WO2013041649A1

WO2013041649A1 - Use of an aqueous dispersion of biodegradable polyesters

Info

Publication number: WO2013041649A1
Application number: PCT/EP2012/068584
Authority: WO
Inventors: Liqun Ren; Gimmy Alex Fernandez Ramirez; Hermann Seyffer; Gabriel Skupin
Original assignee: Basf Se
Priority date: 2011-09-23
Filing date: 2012-09-21
Publication date: 2013-03-28
Also published as: EP2758594A1; CA2849663A1

Abstract

The invention relates to the use of an aqueous dispersion of at least one biodegradable polyester in the form of a coating for improving the barrier properties of packaging materials made of paper or cardboard, in particular packaging materials made of recycled paper or cardboard, with respect to mineral oils. The invention further relates to a method for producing barrier coatings on paper or cardboard, in particular on recycled paper or cardboard.

Description

Use of an aqueous dispersion of biodegradable polyester

The present invention relates to the use of an aqueous dispersion of at least one biodegradable polyester in the form of a coating for improving the barrier properties of packaging materials made of paper or cardboard, in particular packaging materials made of recycled paper or cardboard, compared to mineral oils. The present invention also relates to a process for the preparation of barrier coatings on paper or board, in particular on recycled paper or board.

Paper and cardboard packaging is often made from recycled paper. In the case of printed paper, especially newsprint, the recycled paper may contain mineral oil residues, e.g. B. from the commonly used for newspaper printing inks contain. Even at room temperature volatiles of these residues evaporate and beat in the case of food packaging on the packaged in the box food, such. As noodles, grits, rice or cornflakes, down. Most of the inner bags made from polymer films used today also do not provide adequate protection. Studies by the Cantonal Laboratory of Zurich have revealed significant levels of residual oil in food packaged in recycled paper packaging. The volatile mineral oil constituents are predominantly harmful paraffin and naphthenic hydrocarbons and aromatic hydrocarbon substances, in particular those having 15 to 25 C atoms.

There is therefore a need to reduce the risk of contamination of foods with mineral oil residues. One possibility would be to refrain from recycling newsprint in the manufacture of cardboard packaging for food packaging. This is undesirable for environmental reasons and not practical because of insufficient available amounts of fresh cellulose. Another solution would be to dispense with mineral oils in the printing inks for newspaper printing. However, this encounters technological obstacles, especially with regard to the wiping resistance of the printing on the paper surface.

Paper or paperboard packaging materials are often provided with a barrier coating to reduce penetration of the vegetable or animal fats or oils contained in food. In WO 2006/053849, for example, coatings based on water-based (meth) acrylate polymer dispersions, for. As styrene-acrylate polymer dispersions described for paper and cardboard. The polymers show good barrier properties against liquid oils and fats. However, it has been shown that a good barrier action against liquid oils and fats does not necessarily have a good barrier action against volatile mineral oils, in particular with respect to gaseous mineral oils, eg. B. health-critical paraffin and naphthenic hydrocarbons and aromatic hydrocarbons, especially those having 15 to 25 carbon atoms, given because it is different transport mechanisms for the substances passing through. In the case of liquid fats and oils, transport takes place via the fibers, whereby capillary forces and surface wetting play a role. In the case of problems with gaseous substances capillary action and wetting play no role, but sorption, diffusion and porosity. In addition, fats and oils differ from hydrocarbons, ie from mineral oil constituents in their polarity and thus in their diffusion behavior through barrier layers. From the earlier patent application PCT / EP201 1/054471 aqueous polyester dispersions of biodegradable polyester are known. The polyester dispersions are used inter alia for coating paper. Coatings produced in this way have a good barrier action against vegetable oils and fatty acids. A barrier effect against mineral oils, in particular volatile substances, is not mentioned.

It has now surprisingly been found that good barrier action against mineral oils, in particular with respect to gaseous mineral oils, can be achieved by coating paper or board with aqueous polyester dispersions. In particular, the barrier effect can be improved with the same coating thickness by applying the polyester dispersion to the paper or cardboard in at least two layers. In addition, since the polyesters contained in the dispersions are biodegradable, a better compostability of the coated packaging materials is achieved.

Accordingly, the present invention relates to the use of aqueous dispersions of at least one biodegradable polyester, as defined herein and in the following, in the form of a coating to improve the barrier properties of paper or paperboard packaging material to mineral oils, especially volatile mineral oils, especially gaseous mineral oils , especially those having 15 to 25 carbon atoms, for. B. harmful paraffin and naphthenic hydrocarbons and aromatic hydrocarbons. Due to their high barrier effect against the aforementioned mineral oils, the aqueous dispersions of the at least one biodegradable polyester are particularly suitable for the production of barrier coatings on paper or paper Cardboard produced from recycled paper and thus mineral oil residues, in particular volatile mineral oil residues, especially those with 15 to 25 carbon atoms, eg. For example, contain harmful paraffin and naphthenic hydrocarbons and aromatic hydrocarbons.

Accordingly, a preferred embodiment of the invention relates to the use of aqueous dispersions of at least one biodegradable polyester, as defined herein and in the following, in the form of a coating to improve the barrier properties of paper or paperboard packaging material to mineral oils, the packaging material at least in part , was usually at least 30 wt .-% (wt .-%, based on total fiber mass), in particular at least 50 wt .-% or completely made of mineral oil loaded recycled paper. Accordingly, a preferred embodiment of the invention relates to the use of aqueous dispersions of at least one biodegradable polyester, as defined herein and in the following, in the form of a coating to improve the barrier properties of paper or paperboard to mineral oils, the Paper or the cardboard or the packaging material at least in part, generally at least 30 wt .-% (wt .-%, based on total fiber mass), in particular at least 50 wt .-% or was completely made of mineral oil loaded recycled paper, in particular, such a packaging material intended for food packaging. These include sales packaging, such as boxes or papers, but also consumer packaging, such as disposable tableware, z. As plates, cups or cups made of cardboard.

The coating according to the invention is located on at least one of the paper or board surfaces or on at least one surface of the packaging material. It can also be at least one, z. B. at least one or in particular two, of a plurality of layers of a multilayer coating of the paper, or the carton or the packaging material. The coating according to the invention can be arranged directly on a surface of the flat carrier material (paper or cardboard). However, other layers may also be present between the carrier material and the coating according to the invention, eg. B. primer layers, other barrier layers or colored or black and white ink layers. The coating according to the invention is preferably located on the inner side of the packaging material facing the packaged product. In general, a sufficient barrier effect is achieved if the coating has a coverage of at least 1 g / m ² , often at least 2 g / m ² , especially at least 3 g / m ² and especially at least 5 g / m ² , calculated as solids per m ² coated surface. The coating preferably has a coating thickness in the range from 2 to 50 g / m ² , in particular from 3 to 40 g / m ² , especially from 5 to 30 g / m ² , calculated as solids per m ^{2 of} the coated surface. The coating thickness is accordingly on average at least 1 μηη, often at least 2 μηη, in particular at least 3 μηη and especially at least 5 μηη, z. B. in the range of 2 to 50 μηη, in particular 3 to 40 μηη, especially 5 to 30 μηη.

A specific embodiment of the invention relates to the use for coating cardboard, in particular cardboard, which at least in part, as a rule at least 30 wt .-% (wt .-%, based on total fiber mass), in particular at least 50 wt. -% or completely made from mineral oil loaded recycled paper. In this case, the coating usually has a coverage of at least 2 g / m ² , often at least 3 g / m ² , especially at least 4 g / m ² and especially at least 5 g / m ² , calculated as solids per m ^{2 of} the coated cardboard top - surface, up. The coating preferably has a coating thickness in the range of 3 to 50 g / m ² , in particular 4 to 40 g / m ² , especially 5 to 30 g / m ² , calculated as solids per m ^{2 of} the coated board surface. The coating thickness is accordingly on average at least 2 μηη, often at least 3 μηη, in particular at least 4 μηη and especially at least 5 μηη, z. B. in the range of 2 to 50 μηη, in particular 3 to 40 μηη, especially 5 to 30 μηη.

A further embodiment of the invention relates to the use for coating paper, in particular paper, which is at least partially, as a rule at least 30% by weight (wt .-%, based on total fiber mass), in particular at least 50 wt .-% or made entirely of mineral oil-loaded recycled paper. In this case, the coating has a coating thickness of generally at least 1 g / m ² , often at least 2 g / m ² , in particular at least 3 g / m ² , calculated as solids per m ^{2 of} the coated paper surface on. The coating preferably has a coating thickness in the range of 1 to 30 g / m ² , in particular 2 to 25 g / m ² , especially 3 to 20 g / m ² , calculated as solids per m ^{2 of} the coated paper surface. The coating thickness is accordingly on average at least 1 μηη, often at least 2 μηη, in particular at least 3 μηη, z. B. in the range of 12 to 30 μηη, in particular 2 to 25 μηη, especially 3 to 20 μηη. The coating of the invention may be one or more preferably, for. B. two, three, four or five, arranged on each other layers, which were prepared using the aqueous polyester dispersion. The thickness of the individual layers of the coating will generally amount to at least 0.5 g / m ² , often at least 1 g / m ² , in particular at least 2 g / m ² , especially at least 3 g / m ² and is typically in the Range of 1 to 30 g / m ² , in particular 1 to 25 g / m ² , especially 2 to 20 g / m ² or 2 to 12 g / m ² , calculated as solids per m ^{2 of} the coated surface. Preferably, the coating according to the invention at least two, in particular two, three, four or five and especially two or three layers arranged on one another, which have been produced using the aqueous polyester dispersion. With regard to the overall coating thickness, the foregoing applies. Aqueous dispersions of biodegradable polyesters are known from the earlier patent application PCT / EP201 1/054471 and the prior art cited therein or can be prepared in analogy to the method described there, to which reference is hereby made in full become. In general, biodegradability means that the polyesters disintegrate in a reasonable and detectable period of time. The degradation is usually hydrolytic and is mainly caused by the action of microorganisms such as bacteria, yeasts, fungi and algae or by the hydro- rolases contained therein. The biodegradability can be z. B. determine by mixing polyester with compost and stored for a certain time. For example, in accordance with ASTM D 5338, ASTM D 6400 and DIN V 54900, C0 ₂ -free air is allowed to flow through ripened compost during composting and subjected to a defined temperature program. Here, biodegradability is defined as the ratio of the net CO 2 release of the sample (after subtraction of CO 2 release by the compost without sample) to the maximum CO 2 release of the sample (calculated from the carbon content of the sample). Biodegradable polyester usually show after a few days of composting significant degradation phenomena such as fungal growth, crack and hole formation. Such polyesters are known to those skilled in the art and are commercially available.

The polyesters contained in the aqueous dispersions are typically insoluble in water and are therefore present in the form of particles in the dispersion used according to the invention. The weight-average particle diameter of the polymer particles (weight average, determined by light scattering) in these dispersions will generally not exceed 10 μm, often 5 μm, in particular 2000 nm, especially 1500 nm and is typically in the range from 50 nm to 10 μηη, often in the range of 100 nm to 5 μηη, in particular in the range of 150 to 2000 nm, especially in the range of 200 to 1500 nm. Preferably, less than 90 wt .-% of the polymer particles have a particle diameter of 10 μηη, in particular 5 μηη and especially 2 μηη not exceed. The determination of the particle size is carried out in a conventional manner by light scattering on dilute dispersions (0.01 to 1 wt .-%).

Biodegradable polyesters are, for example, the polyesters from the groups of aliphatic polyesters, aliphatic copolyesters, aliphatic-aromatic copolyester. Also suitable are blends of the aforementioned biodegradable polyesters with one another or blends with other, biodegradable, preferably water-insoluble polymers, eg. As starch or polyalkylene. Examples of such Blends are blends of at least one aliphatic copolyester with at least one polymer from the group starch, polyalkylene and aliphatic polyesters such as polylactic acid or polyhydroxyalkanoates and blends of at least one aliphatic-aromatic copolyester with at least one polymer from the group starch, polyalkylene and aliphatic polyesters such as polylactic acid or polyhydroxyalkanoates. In general, the proportion of the biodegradable polyester will be at least 30% by weight, in particular at least 40% by weight, based on the total solids content of the dispersion. In a preferred embodiment, those dispersions are used in which the polyester is the sole water-insoluble, ie dispersed, polymer constituent or the proportion of the biodegradable polyester is at least 80% by weight, in particular at least 90% by weight, based on the total solids content of the dispersion, is. In another embodiment, those dispersions are used which contains, in addition to the biodegradable polyester, at least one further water-insoluble, ie dispersed, polymer constituent, which is preferably likewise biodegradable. The proportion of the biodegradable polyester will then generally be from 30 to 90% by weight, in particular from 40 to 80% by weight, based on the total solids content of the dispersion. The proportion of the dispersed polymer component other than the polyester is then usually from 10 to 70% by weight, in particular from 20 to 60% by weight, based on the total amount of the polymers dispersed in the dispersion. Suitable further dispersed polymer constituents which may be included in the dispersion together with the polyester are also preferably biodegradable and selected, for example, from starch and polyalkylene carbonates.

The polyesters contained in the dispersions used according to the invention typically have a number average molecular weight MN in the range from 5000 to 1,000,000 daltons, in particular in the range from 8,000 to 800,000 daltons and especially in the range from 10,000 to 500,000 daltons. The weight-average molecular weight Mw of the polymer is typically in the range of 20,000 to 500,000 daltons, often in the range of 30,000 daltons to 4,000,000 daltons, and more preferably in the range of 40,000 to 2,500,000 daltons. The polydispersity index MW / MN is generally at least 2 and is often in the range from 3 to 20, in particular in the range from 5 to 15. Molecular weight and polydispersity index can be determined, for example, by gel permeation chromatography (GPC) according to DIN 55672-1 ,

The viscosity number of the polyesters, which is indirectly a measure of the molecular weight, is typically in the range of 50 to 500 ml / g, often in the range of 80 to 300 ml / g and especially in the range of 100 to 250 ml / g (determined according to EN ISO 1628-1 at 25 ° C on a 0.5 wt .-% solution of the polymer in o-dichlorobenzene / phenol (1: 1 w / w)). The polyesters contained in the dispersions used according to the invention may be amorphous or partially crystalline. In a preferred embodiment of the invention, the polyester contained in the dispersion is essentially unbranched, ie the degree of branching generally has a value of <0.005 mol / kg, in particular <0.001 mol / kg and especially <0.0005 mol / kg , In another embodiment of the invention, the polyester is branched, wherein the degree of branching preferably does not exceed a value of 1 mol / kg, in particular 0.5 mol / kg and especially 0.3 mol / kg. The degree of branching is understood to mean the number of monomer units condensed in which more than two, e.g. B. three, four, five or six suitable for condensation functional groups that react with carboxylic acid or hydroxyl groups under bond formation, for. As carboxylate, OH, isocyanate (NCO) or NH2 groups (or ester or amide-forming derivatives thereof). In this embodiment, the polyester has a degree of branching of generally 0.0005 to 1 mol / kg, preferably 0.001 to 0.5 mol / kg, and more preferably 0.005 to 0.3 mol / kg. In particular, the biodegradable polyester is selected from the group of aliphatic polyesters, aliphatic copolyesters, aliphatic-aromatic copolyesters and mixtures thereof.

An aliphatic polyester is understood as meaning a polyester which is composed exclusively of aliphatic monomers. An aliphatic copolyester is understood as meaning a polyester which is composed exclusively of at least two, in particular at least three, aliphatic monomers, the acid component and / or the alcohol component preferably comprising at least two mutually different monomers. An aliphatic-aromatic copolyester is understood as meaning a polyester which is composed both of aliphatic monomers and of aromatic monomers, wherein the acid component preferably comprises at least one aliphatic acid and at least one aromatic acid.

Among the aliphatic polyesters and copolyesters are in particular polylactides (polylactic acid), polycaprolactone, block copolymers of polylactide with P0IV-C2-C4-alkylene glycol, block copolymers of polycaprolactone with poly-C2-C4-alkylene glycol and the copolyesters defined below, which consist of at least one aliphatic or cycloaliphatic dicarboxylic acid or an ester-forming derivative thereof and at least one aliphatic or cycloaliphatic diol component and, if appropriate, further components. The term "polylactides" is to be understood as meaning polycondensation products of lactic acid. Suitable polylactides are described in WO 97/41836, WO 96/18591,

WO 94/05484, US 5,310,865, US 5,428,126, US 5,440,008, US 5,142,023,

US 5,247,058, US 5,247,059, US 5,484,881, WO 98/09613, US 4,045,418,

US 4,057,537 and Adv. Mater. 2000, 12, 1841-1846. These products are lactic acid lactone-based polymers (A), which are converted by ring-opening polymerization into polylactic acid polymers (B):

The degree of polymerization n in formula (B) is in the range from 1000 to 4000, preferably from 1500 to 3500 and more preferably from 1500 to 2000 (number average). The average molecular weights (number average) of these products are in the range of 71,000 to 284,000 g / mol according to the degree of polymerization. Suitable polylactides are for. Available from Cargill Dow LLC (eg PLA Polymer 404ID, PLA Polymer 4040D, PLA Polymer 4031D, PLA Polymer 2000D or PLA Polymer 1 100) or from Mitsui Chemicals (Lactea). Also suitable are diblock and tri-block copolymers of polylactides with poly-C 2 -C 4 -alkylene glycol, in particular with poly (ethylene glycol). These block copolymers are marketed, for example, by Aldrich (eg, product number 659649). These are polymers comprising polylactide blocks and poly-C 2 -C 4 -alkylene oxide blocks. Such block copolymers are z. B. by condensation of lactic acid or by ring-opening polymerization of lactic acid lactone (A) in the presence of poly-C2-C4-alkylene glycols available.

Biodegradable polyesters suitable according to the invention are also polycaprolactones. By those skilled in the art means polymers which are described by the formula D shown below, where n is the number of repeating units in the polymer, d. H. means the degree of polymerization.

The degree of polymerization n in formula (D) is in the range of 100 to 1000, preferably 500 to 1000 (number average). The number average molecular weights of these products are in the range of 10,000 g / mol to corresponding degree of polymerization

100000 g / mol. Particularly preferred polymers of the formula (D) have average molar masses (number average) of 50,000 g / mol (CAPA 6500), 80,000 g / mol (CAPA 6800) and 100,000 g / mol (CAPA FB 100). Polycaprolactones are generally prepared by ring-opening polymerization of ε-caprolactone (compound C) in the presence of a catalyst. Polycaprolactones are available from Solvay under the designation CAPA polymers, e.g. CAPA 6100, 6250, 6500 or CAPA FB 100, commercially available. Suitable polymers are furthermore diblock and triblock copolymers of polycaprolactone with poly-C 2 -C 4 -alkylene glycols, in particular with polyethylene glycols (= polyethylene oxides), ie polymers which have at least one polycaprolactone block of the formula D and at least one polyalkylene glycol block. Such polymers may, for. B. by polymerization of caprolactone in the presence of polyalkylene glycols, for example, analogously to the Macromolecules 2003, 36, pp 8825- 8829 described method can be prepared.

Biodegradable polyesters which are suitable according to the invention are in particular copolyesters which are synthesized from at least one aliphatic or cycloaliphatic dicarboxylic acid or an ester-forming derivative thereof and at least one aliphatic or cycloaliphatic diol component and optionally further components.

In particular, the polymer to be dispersed according to the invention is an aliphatic or aliphatic-aromatic copolyester which is essentially composed of:

a) at least one dicarboxylic acid component A, consisting of

a1) at least one aliphatic or cycloaliphatic dicarboxylic acid or its ester-forming derivatives or mixtures thereof (component a1) and

a2) if appropriate, one or more aromatic dicarboxylic acids which have no sulfonic acid group, or their ester-forming derivatives or mixtures thereof ((component a2),

a3) optionally one or more aromatic dicarboxylic acids which have at least one sulfonic acid group, or their ester-forming

Derivatives or mixtures thereof (component a3);

consists;

b) at least one diol component B selected from aliphatic and cycloaliphatic diols and mixtures thereof;

c) optionally one or more other bifunctional compounds C which react with carboxylic acid or hydroxyl groups to form bonds; and

d) optionally one or more compounds D, the at least three, z. Have three, four or five functionalities which react with carboxylic acid or hydroxyl groups to form bonds; wherein the molar ratio of component A to component B is generally in the range of 0.4: 1 to 1: 1, in particular in the range of 0.6: 1 to 0.99: 1 and the components A and B in the Generally account for at least 80 wt .-%, in particular at least 90 wt .-% and especially at least 96 wt .-% of all ester-forming constituents of the polyester or the total weight of the polyester.

Here and in the following, aliphatic copolyesters are understood to mean those copolyesters which contain, as component A, exclusively component a1). Here and below, aliphatic-aromatic copolyesters are understood as meaning those copolyesters which contain as component A both the component a1) and the component a) and optionally a3) in a condensed form.

Here and below, the statements in% by weight based on the ester-forming constituents refer to the constituents of the components A, B, C and D in a condensed form and thus to the total mass of the polyester and not to the amounts used to prepare the polyester, unless otherwise stated.

In these copolyesters, the acid component A preferably comprises

a1) 30 to 100 mol%, in particular 35 to 90 mol% or 40 to 90 mol% of at least one aliphatic or at least one cycloaliphatic dicarboxylic acid or its ester-forming derivatives or mixtures thereof,

a2) 0 to 70 mol%, in particular 10 to 65 mol% or 10 to 60 mol% of at least one aromatic dicarboxylic acid or its ester-forming derivative or mixtures thereof,

a3) 0 to 5 mol%, in particular 0 to 3 mol% or 0 to 2 mol%, of one or more aromatic dicarboxylic acids which have at least one sulfonic acid group, or their ester-forming derivatives or mixtures thereof

the molar percentages of components a1), a2) and a3) together amount to 100%.

In preferred embodiments of the invention, aqueous dispersions of copolyesters are used whose acid component A comprises the following constituents:

a1) 35 to 90 mol% or 40 to 90 mol% and especially 60 to 90 mol% of at least one aliphatic or at least one cycloaliphatic dicarboxylic acid or its ester-forming derivatives or mixtures thereof,

a2) 10 to 65 mol% or 10 to 60 mol% and especially 10 to 40 mol% of at least one aromatic dicarboxylic acid or its ester-forming derivative or mixtures thereof,

a3) 0 to 5 mol%, in particular 0 to 3 mol% or 0 to 2 mol%, of one or more aromatic dicarboxylic acids which have at least one sulfonic acid group, or their ester-forming derivatives or mixtures thereof the molar percentages of components a1), a2) and a3) together amount to 100%.

The acid component A may contain small amounts of a sulfonated aromatic dicarboxylic acid z. As sulfoisophthalic acid or a salt thereof, condensed, wherein the proportion of sulfonated carboxylic acid usually not more than 5 mol%, often not more than 3 mol%, in particular not more than 2 mol% is and z. B. in the range of 0.1 to 5 mol% or 0.1 to 3 mol% or 0.2 to 2 mol%, based on the total amount of compounds of component A. In one embodiment of the invention, the amount of sulfonated carboxylic acids is less than 1 mol%, in particular less than 0.5 mol%, based on the component A. In another embodiment of the invention, such copolyesters have from 0.01 to 0 , 2 mmol / g, in particular 0.05 to 0.15 mmol / g sulfonic acid groups. In a further embodiment of the invention, such copolyesters have less than 0.05 mmol / g, in particular less than 0.01 mmol / g sulfonic acid groups.

Among the preferred copolyesters, particular preference is given to those in which the proportion of diol component B is 98 to 102 mol%, in particular 99 to 101 mol%, based on the total amount of components a1), a2) and optionally a3). Among the particularly preferred copolyesters, particular preference is given to those in which the polyester-forming constituents contain not more than 2% by weight, in particular not more than 1% by weight, based on the total weight of the polyester, of one or more further bifunctional compounds C which react with carboxylic acid or hydroxyl groups to form bonds.

Among the particularly preferred copolyesters, particular preference is given to those in which the polyester-forming constituents contain not more than 2% by weight, in particular not more than 1% by weight, based on the total weight of the polyester, of one or more compounds D which are at least three , z. B. have three, four or five functionalities which react with carboxylic acid or hydroxyl groups to form bonds.

In the preferred copolyesters, components a1), a2), a3) and b) in particular comprise 96 to 100% by weight, in particular 98 to 100% by weight, of such copolyesters.

In a specific embodiment of the invention are aqueous dispersions of partially aromatic or aliphatic-aromatic copolyesters, which are characterized by the following composition:

a1) 60 to 80 mol%, often 65 to 80 mol%, in particular 66 to 75 mol%, based on the total amount of components a1) and a2) of at least one aliphatic dicarboxylic acid or its ester-forming derivative or mixtures thereof and

a2) 20 to 40 mol%, often 20 to 35 mol%, in particular 25 to 34 mol%, based on the total amount of components a1) and a2), terephthalic acid or their ester-forming derivatives or mixtures thereof;

b) from 98 to 102 mole%, of at least one diol component b) selected from 1,3-propanediol and 1,4-butanediol and mixtures thereof;

d) 0.1 to 2 wt .-%, often 0.2 to 2 wt .-%, in particular 0.3 to 1, 8 wt .-% and especially 0.4 to 1, 5 wt .-%, based to the total amount of components a1), a2), in each case calculated as dicarboxylic acids, and b), one or more compounds D which have at least three functionalities which react with carboxyl or hydroxyl groups to form bonds;

wherein the components a1), a2) and b) 80 to 99.8 wt .-%, in particular 90 to 99.7 wt .-%, and especially 95 to 99.6 wt .-% of the polyester make up.

Aliphatic dicarboxylic acids a1) which are suitable according to the invention generally have 2 to 10 carbon atoms, preferably 4 to 8 and in particular 6 carbon atoms. They can be both linear and branched. The cycloaliphatic dicarboxylic acids which can be used in the context of the present invention are as a rule those having 7 to 10 carbon atoms and in particular those having 8 carbon atoms. In principle, however, it is also possible to use dicarboxylic acids having a larger number of carbon atoms, for example having up to 30 carbon atoms. Examples which may be mentioned are malonic acid, succinic acid, glutaric acid, 2-methylglutaric acid, 3-methylglutaric acid, adipic acid, pimelic acid, azelaic acid, sebacic acid, fumaric acid, 2,2-dimethylglutaric acid, suberic acid, 1,3-cyclopentanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid , 1, 3-cyclohexanedicarboxylic acid, diglycolic acid, itaconic acid, maleic acid and 2,5-Norbornandicarbonsäure. Other suitable ester-forming derivatives of the abovementioned aliphatic or cycloaliphatic dicarboxylic acids which are likewise usable are the di-C 1 to C 6 alkyl esters, such as dimethyl, diethyl, di-n-propyl, diisopropyl, di-n butyl, di-iso-butyl, di-t-butyl, di-n-pentyl, di-iso-pentyl or di-n-hexyl esters. Anhydrides of dicarboxylic acids can also be used. Preferred dicarboxylic acids are succinic acid, adipic acid, sebacic acid, azelaic acid and brassylic acid and their respective ester-forming derivatives or mixtures thereof. Particularly preferred are adipic acid, sebacic acid or succinic acid and their respective ester-forming derivatives or mixtures thereof.

The aromatic dicarboxylic acids a2 are generally those having 8 to 12 carbon atoms and preferably those having 8 carbon atoms. Examples include terephthalic acid, isophthalic acid, 2,6-naphthoic acid and 1, 5-naphthoic acid and ester-forming derivatives thereof. In particular, the D1-C1-C6 alkyl esters, z. As dimethyl, diethyl, diethyl, di-n-propyl, diisopropyl, di-n-butyl, di- iso-butyl, di-t-butyl, di-n-pentyl, di-iso-pentyl or di-n-hexyl ester. The anhydrides of the dicarboxylic acids a2 are also suitable ester-forming derivatives. In principle, however, it is also possible to use aromatic dicarboxylic acids a2 having a larger number of carbon atoms, for example up to 20 carbon atoms. The aromatic dicarboxylic acids or their ester-forming derivatives a2 may be used singly or as a mixture of two or more thereof. Particularly preferred is terephthalic acid or its ester-forming derivatives such as dimethyl terephthalate used. The sulfonated aromatic dicarboxylic acids and their ester-forming derivatives are typically derived from the aforementioned non-sulfonated aromatic dicarboxylic acids and carry one or two sulfonic acid groups. To name a few examples is sulfoisophthalic acid or a salt thereof z. As the sodium salt (Nasip). Generally, the diols B are selected from branched or linear alkanediols of 2 to 12 carbon atoms, preferably 4 to 8 or more preferably 6 carbon atoms, or cycloalkanediols of 5 to 10 carbon atoms.

Examples of suitable alkanediols are ethylene glycol, 1, 2-propanediol, 1, 3-propanediol, 1, 2-butanediol, 1, 4-butanediol, 1, 5-pentanediol, 2,4-dimethyl-2-ethylhexane-1, 3 diol, 2,2-dimethyl-1, 3-propanediol, 2-ethyl-2-butyl-1,3-propanediol, 2-ethyl-2-isobutyl-1,3-propanediol, 2,2,4-trimethyl 1, 6-hexanediol, in particular ethylene glycol, 1, 3-propanediol, 1, 4-butanediol and 2,2-dimethyl-1, 3-propanediol (neopentyl glycol); Cyclopentanediol, 1, 4-cyclohexanediol, 1, 2-cyclohexanedimethanol, 1, 3-cyclohexanedimethanol,

1,4-cyclohexanedimethanol or 2,2,4,4-tetramethyl-1,3-cyclobutanediol. It is also possible to use mixtures of different alkanediols. In these copolyesters, the diol component B is preferably selected from C 2 -C 12 -alkanediols and mixtures thereof. Preference is given to 1, 3-propanediol and in particular

1, 4-butanediol.

Depending on whether an excess of OH end groups is desired, component B can be used in excess. According to a preferred embodiment, the molar ratio of the components A used to B in the range from 0.4: 1 to 1, 1: 1, preferably in the range of 0.6: 1 to 1, 05: 1 and in particular in the range of 0 , 7: 1 to 1, 02: 1. The molar ratio of the component A incorporated in the polymer to the component B incorporated in the polymer is preferably in the range from 0.8: 1 to 1:01: 1, preferably in the range from 0.9: 1 to 1: 1, and in particular in the range of 0.99: 1 to 1: 1.

In addition to components A and B, the polyesters may contain further bifunctional components C in condensed form. These bifunctional compounds have two functional groups which react with carboxylic acid groups or preferably hydroxyl groups to form bonds. Examples of functional groups, wel- surface with OH groups, are in particular isocyanate groups, epoxy groups, oxazoline groups, carboxyl groups in free or esterified form and amide groups. Functional groups which react with carboxyl groups are in particular hydroxyl groups and primary amino groups. These are in particular so-called bifunctional chain extenders, in particular the compounds of groups c3) to c7). The components C include: c1) dihydroxy compounds of the formula I.

HO - [(A) -O] _m -H (I) where A is a C2-C4-alkylene unit such as 1,2-ethanediyl, 1,2-propanediyl,

1, 3-propanediyl or 1, 4-butanediyl, and m is an integer from 2 to 250;

Hydroxycarboxylic acids of the formula IIa or IIb

(IIa) where p is an integer from 1 to 1500 and r is an integer from 1 to 4, and G is a radical selected from the group consisting of phenylene, - (CH 2) _q -, wherein q is an integer from 1 to 5, -C (R) H- and -C (R) HCH ₂ , wherein R is methyl or ethyl; c3) amino-C2-Ci2-alkanols, amino-Cs-C-io-cycloalkanols or mixtures thereof;

Diamino-Ci-Ce-alkanes;

2,2'-bisoxazolines of the general formula III

(III) wherein Ri represents a single bond, a (CH 2) _Z alkylene group, with z = 2, 3 or 4, or a phenylene group; Aminocarboxylic acids, for example, are selected from natural amino acids, polyamides having a molecular weight of at most 18000g / mol, obtainable by polycondensation of a dicarboxylic acid having 4 to 6 carbon atoms and a diamine having 4 to 10 carbon atoms, compounds of formulas IV a and IVb

(IVa) (IVb) in which s is an integer from 1 to 1500 and t is an integer from 1 to 4, and T is a radical selected from the group consisting of phenylene, - (Chbju-, wherein u is an integer from 1 to 12, -C (R ² ) H- and -C (R ² ) HCH ₂ , wherein R ^{2 is} methyl or ethyl, and polyoxazolines having the repeating unit V

(V) in which R ^{3 is} hydrogen, C 1 -C 6 -alkyl, C 3 -C 8 -cycloalkyl, phenyl which is unsubstituted or monosubstituted or substituted by C 1 -C 4 -alkyl groups or is tetrahydrofuryl; and

Diisocyanates.

Examples of component c1 are diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol and polytetrahydrofuran (polyTHF), particularly preferably diethylene glycol, triethylene glycol and polyethylene glycol, mixtures of which or compounds having different alkylene units A (see formula I), For example, polyethylene glycol containing propylene units (A = 1, 2- or 1, 3-propanediyl) can use. The latter are obtainable, for example, by polymerization according to known methods of first ethylene oxide and subsequently propylene oxide. Particular preference is given to copolymers based on polyalkylene glycols with different variables A, where units formed from ethylene oxide (A = 1, 2-ethanediyl) predominate. The molecular weight (number average M _n ) of the polyethylene glycol is usually selected in the range from 250 to 8000, preferably from 600 to 3000 g / mol. According to one embodiment, for example, 80 to 99.8, preferably 90 to 99.5 mol% of the diols B and 0.2 to 20, preferably 0.5 to 10 mol% of the dihydroxy compounds c1, based on the molar Amount of B and c1, used for the preparation of copolyesters.

Examples of preferred components c2 are glycolic acid, D-, L-, D, L-lactic acid, 6-hydroxyhexanoic acid, their cyclic derivatives such as glycolide (1,4-dioxane-2,5-dione), D-, L-dilactide ( 3,6-dimethyl-1, 4-dioxane-2,5-dione), p-hydroxybenzoic acid and also their oligomers and polymers such as 3-polyhydroxybutyric acid, polyhydroxyvaleric acid, polylactide (for example as EcoPLA® (from Cargill)) ) and a mixture of 3-polyhydroxybutyric acid and polyhydroxyvaleric acid (the latter being available under the name Biopol® from Zeneca). Particularly preferred for the preparation of copolyesters are the low molecular weight and cyclic derivatives thereof. The hydroxycarboxylic acids, or their oligomers and / or polymers, can be used, for example, in amounts of from 0.01 to 20, preferably from 0.1 to 10,% by weight, based on the amount of A and B.

Preferred components c3 are amino-C2-C6-alkanols such as 2-aminoethanol,

3-aminopropanol, 4-aminobutanol, 5-aminopentanol, 6-aminohexanol and amino C5-C6 cycloalkanols such as aminocyclopentanol and aminocyclohexanol or mixtures thereof.

Preferred components c4) are diamino-C 4 -C 6 -alkanes, such as 1,4-diaminobutane, 1,5-diaminopentane and 1,6-diaminohexane.

According to a preferred embodiment, 0.5 to 20 mol%, preferably 0.5 to 10 mol%, of c3, based on the molar amount of B, and from 0 to 15, preferably from 0 to 10 mol%, c4, based on the molar amount of B, used for the preparation of copolyesters.

Preferred bisoxazolines III of component c5) are those in which R ^{1 is} a single bond, a (CH 2) _Z -alkylene group, with z = 2, 3 or 4, such as methylene, ethane-1, 2-diyl, propane-1, 3 diyl, propane-1, 2-diyl, or a phenylene group. Particularly preferred bisoxazolines are 2,2'-bis (2-oxazoline), bis (2-oxazolinyl) methane, 1, 2-bis (2-oxazolinyl) ethane, 1, 3-bis (2-oxazolinyl) propane or 1,4-bis (2-oxazolinyl) butane, 1,4-bis (2-oxazolinyl) benzene, 1,2-bis (2-oxazolinyl) benzene or 1,3-bis (2-oxazolinyl) called benzene. Bisoxazolines of general formula III are generally obtainable by the process of Angew. Chem. Int. Edit, Vol. 11 (1972), pp. 287-288. For example, from 80 to 98 mole% B, up to 20 mole% c3, e.g. B. 0.5 to 20 mol% c3, up to 20 mol%, z. B. 0.5 to 20 mol% c4, and up to 20 mol%, z. B. 0.5 to 20 mol% c5, in each case based on the sum of the molar amounts of components B, c3, c4 and c5, are used. According to another preferred embodiment, it is possible to use from 0.1 to 5% by weight, preferably from 0.2 to 4% by weight of c5, based on the total weight of A and B.

As component c6 natural aminocarboxylic acids can be used. These include valine, leucine, isoleucine, threonine, methionine, phenylalanine, tryptophan, lysine, alanine, arginine, aspartic acid, cysteine, glutamic acid, glycine, histidine, proline, serine, tyrosine, asparagine or glutamine.

Preferred aminocarboxylic acids of the general formulas IVa and IVb are those in which s is an integer from 1 to 1000 and t is an integer from 1 to 4, preferably 1 or 2 and T is selected from the group consisting of phenylene and - (Chkju-, wherein u is 1, 5 or 12.

Furthermore, c6 can also be a polyoxazoline of the general formula V. However, component c6 can also be a mixture of different aminocarboxylic acids and / or polyoxazolines.

In a preferred embodiment, c6 can be used in amounts of from 0.01 to 20, preferably from 0.1 to 10,% by weight, based on the total amount of components A and B.

As component c7 it is possible to use aromatic or aliphatic diisocyanates. However, it is also possible to use higher-functionality isocyanates. Examples of aromatic diisocyanates are toluylene-2,4-diisocyanate, toluylene-2,6-diisocyanate, 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, naphthylene-1,5-diisocyanate or xylylene diisocyanate. Examples of aliphatic diisocyanates are, above all, linear or branched alkylene diisocyanates or cycloalkylene diisocyanates having 2 to 20 carbon atoms, preferably 3 to 12 carbon atoms, eg. B. 1, 6-hexamethylene diisocyanate, isophorone diisocyanate or methylene bis (4-isocyanatocyclohexane). Further suitable components c7 are tri (4-isocyanatophenyl) methane and the cyanurates, uretdiones and biurets of the abovementioned diisocyanates.

In general, the component c7, if desired, in amounts of from 0.01 to 5, preferably 0.05 to 4 mol%, particularly preferably 0.1 to 4 mol% based on the sum of the molar amounts of A and B used , Other components which may optionally be used to prepare the polyesters include compounds D which contain at least three groups / functionalities which react with carboxylic acid or hydroxyl groups to form bonds. Examples of functional groups which react with OH groups are, in particular, isocyanate groups, epoxide groups, oxazoline groups, carboxyl groups in free or esterified form and amide groups. Functional groups which react with carboxyl groups are in particular hydroxyl groups and primary amino groups. Such compounds are also referred to as crosslinkers. By means of compound D, biodegradable copolyesters with a structural viscosity can be built up. The rheological behavior of the melts improves; The biodegradable copolyesters are easier to process, for example, better by melt consolidation to remove films. The compounds D act scherentzä- Hend, ie the viscosity under load is lower. The compounds D preferably contain three to ten, z. , Three, four, five or six, functional groups capable of forming ester bonds. Particularly preferred compounds D have three to six functional groups of this kind in the molecule, in particular three to six hydroxyl groups and / or carboxyl groups. Examples include: polycarboxylic acids and hydroxycarboxylic acids such as tartaric acid, citric acid, malic acid; trimesic; Trimellitic acid, anhydride; Pyromellitic acid, dianhydride and hydroxyisophthalic acid and polyols such as trimethylolpropane, trimethylolethane; Pentaerythritol, polyether triols and glycerine. Preferred compounds D are polyols, preferably trimethylolpropane, pentaerythritol and especially glycerol. The compounds D are, if desired, usually in amounts of 0.0005 to 1 mol / kg, preferably 0.001 to 0.5 mol / kg and in particular 0.005 to 0.3 mol / kg, based on the total amount of components A, B. , C and D, or on the total weight of the polyester used. If desired, the compounds D are preferably 0.01 to 5% by weight, in particular 0.05 to 3% by weight and in particular 0.1 to 2% by weight, especially 0.2 to 2% by weight. %, based on the total amount of components A, B, C and D, or on the total weight of the polyester used.

In general, it makes sense to add the crosslinking (at least trifunctional) compounds D at an earlier point in time of the polycondensation.

In addition to the abovementioned components A, B, optionally C and optionally D, it is also possible to use bifunctional or polyfunctional epoxides for the preparation of the copolyesters which are preferred according to the invention (component E). Suitable bi- or polyfunctional epoxides are, in particular, epoxide-group-containing copolymers based on styrene, acrylates and / or methacrylates. The epoxy groups bearing units are preferably glycidyl (meth) acrylates. Copolymers having a glycidyl methacrylate content of greater than 20, particularly preferably greater than 30 and especially preferably greater than 50% by weight, of the copolymer have proved to be advantageous. The epoxide equivalent weight (EEW) in these polymers is preferably Example 150 to 3000 and particularly preferably 200 to 500 g / equivalent. The weight average molecular weight Mw of the polymers is preferably from 2,000 to 25,000, in particular from 3,000 to 8,000. The number average molecular weight M _{n of} the polymers is preferably from 400 to 6,000, in particular from 1,000 to 4,000. The polydispersity (Q) is generally between 1 .5 and 5 epoxy groups, copolymers of the above type are sold for example by BASF Resins BV under the trademark Joncryl ^® ADR. Particularly suitable as component E Joncryl ^® ADR 4368. The component E is most commonly used as a chain. With regard to the quantity, the statements made above for component E, in particular for components c2), c3), c4), c5) and c6), apply.

The copolyesters are partially known, for. Example, from EP-A 488 617, W096 / 15173 and WO 04/67632, or can be prepared by methods known per se. More preferably, the copolyesters are prepared by the continuous process described in EP Publ. No. 08154541.0.

The synthesis of the copolyesters described is carried out according to a first embodiment in a two-stage reaction cascade. In general, the dicarboxylic acids or their derivatives A are first reacted together with component B and optionally D in the presence of an esterification catalyst (or when the carboxylic acids A are used in the form of their esters, in the presence of a transesterification catalyst) to give a prepolyester. This prepolyester generally has a viscosity number (CV) of 50 to 100 ml / g, preferably 60 to 90 ml / g. The catalysts used are usually zinc, aluminum and in particular titanium catalysts. Titanium catalysts such as tetra (isopropyl) orthotitanate and in particular tetrabutyl orthotitanate (TBOT) have the advantage over the tin, antimony, cobalt and lead catalysts frequently used in the literature, such as tin dioctanoate, that residual amounts of catalyst remaining in the product or secondary products of the catalyst are less toxic. This fact is particularly important in the case of biodegradable polyesters, since, for example, they are released directly into the environment as composting bags or mulch films. The polyesters according to the invention are optionally subsequently chain-extended according to the processes described in WO 96/15173 and EP-A 488 617. The prepolyester is, for example, chain extenders C), z. B. with diisocyanates or with epoxy-containing polymethacrylates in a chain extension reaction to a polyester with a VZ of 60 to

450 mL / g, preferably 80 to 250 mL / g reacted.

In another method, component A is first condensed in the presence of an excess of component B and optionally D together with the catalyst. Subsequently, the melt of the prepolyester thus obtained, usually at an internal temperature of 200 to 250 ° C, while releasing distilled diol to the desired viscosity with a viscosity number (VZ) of 60 to 450 mL / g and preferably 80 to 250 mL / g condensed. This condensation is usually carried out within 3 to 6 hours at reduced pressure. If appropriate, a reaction with the chain extender of component D is also carried out hereinafter. More preferably, the copolyesters are prepared by the continuous process described in EP Publ. No. 08154541.0. In this case, for example, a mixture of the components A and B and optionally further Comonome- ren, without addition of a catalyst, mixed into a paste or alternatively the liquid esters of component A and component B and optionally further comonomers, without addition of a catalyst in fed to the reactor and esterified in a first stage, this mixture, together with the total amount or a partial amount of the catalyst continuously or transesterified; in a second stage optionally with the remainder of the catalyst continuously the transesterification or esterification product obtained according to 1) - preferably in a tower reactor, wherein the product stream is passed in cocurrent over a falling film cascade and the reaction vapors are removed in situ from the reaction mixture - up to a viscosity number according to DIN 53728 of 20 to 60 mL / g precondensed;

in a third stage, the product obtainable from 2.) - preferably in a cage reactor - polycondensed up to a viscosity number according to DIN 53728 of 70 to 130 mL / g and optionally

in a fourth step, the product obtainable from 3.) is continuously converted to a viscosity number according to DIN 53728 of 80 to 250 ml / g in a polyaddition reaction with a chain extender in an extruder, a list reactor or a static mixer.

The abovementioned ranges of viscosity numbers merely serve as indications for preferred process variants, but are not intended to be limiting for the present application subject.

In addition to the continuous process described above, the copolyesters of the invention may also be prepared in a batch process. For this purpose, the components A, B and optionally D are mixed in any metering order and condensed to form a prepolyester. Optionally, with the aid of component D, a polyester can be adjusted with the desired viscosity number.

The preferred copolyesters generally have a number average molecular weight MN in the range from 5000 to 1,000,000 daltons, in particular in the range from 8,000 to 800,000 daltons and especially in the range from 10,000 to 500,000 daltons. The weight-average molecular weight M w of the copolyesters preferred according to the invention is generally in the range from 20,000 to 500,000 daltons, often in the range from 30,000 Daltons to 4,000,000 Daltons, and more particularly in the range of 40,000 to

2500000 daltons. The polydispersity index MW / MN is generally at least 2 and is often in the range of 3 to 25, in particular in the range of 5 to 20. Preferably, the copolyesters are partially crystalline and have a melting point or melting range in the range of 80 to 170 ° C, in particular in the range of 90 to 150 ° C. The viscosity number of the copolyesters is typically in the range of 50 to 500 ml / g, often in the range of 80 to 300 ml / g and in particular in the range of 100 to 250 ml / g (determined according to EN ISO 1628-1 at 25 ° C on a 0.5% strength by weight solution of the polymer in o-dichlorobenzene / phenol (1: 1 w / w)). The preferred copolyesters are on the one hand by a high melt viscosity ηο, which at 180 ° C usually at least 60 Pa-s, often at least 80 Pa-s, in particular at least

100 Pa.s, z. B. 60 to 20,000 Pa-s, in particular 80 to 15,000 Pa-s and especially 100 to 10,000 Pa-s, and by a low acid number of less than 5 mg KOH / g polymer, in particular not more than 3 mg KOH / g polymer and specifically characterized at most 1 mg KOH / g polymer.

Furthermore, the copolyesters preferably have substantially no functional groups which impart water solubility to the polymers. Accordingly, the number of sulfonic acid groups in the copolyester is generally less than 0.1 mmol / g, in particular less than 0.05 mmol / g or less than 0.01 mmol / g of polymer.

The aqueous dispersions of the copolyester generally have a solids content in the range from 10 to 60% by weight, in particular in the range from 20 to 55% by weight and especially in the range from 30 to 50% by weight.

Preferably, the viscosity of the dispersions according to the invention, determined according to Brookfield, at 20 ° C at a value of at most 5 Pa-s, often at a maximum of 2 Pa-s, z. B. in the range of 10 to 5000 mPa-s, in particular in the range of 50 to 2000 mPa-s (measured using a Brookfield viscometer at 20 ° C, 20 rpm, spindle 4).

In addition to the dispersed polymers, the aqueous dispersion generally contains at least one surface-active substance for stabilizing the polymer particles dispersed in the dispersion. The proportion of surface-active substances will generally not exceed 20% by weight, based on the total solids content, and is typically in the range from 0.1 to 20% by weight and frequently in the range from 0.2 to 10% by weight. , based on the total solids content. Suitable surfactants include polymeric surfactants having molecular weights in excess of 2000 daltons (number average), e.g. 2200 to 10 ⁶ daltons, which are generally referred to as protective colloids, and low molecular weight surfactants with molecular weights up to 2000 daltons, often up to 1500 daltons (number average), which are usually referred to as emulsifiers. The surfactants may be cationic, anionic or neutral.

In a preferred embodiment of the invention, the aqueous dispersion medium contains at least one protective colloid, for example a neutral, anionic or cationic protective colloid, optionally in combination with one or more emulsifiers.

Examples of protective colloids are water-soluble polymers such as

neutral protective colloids: for example polysaccharides, e.g. B. water-soluble

Starches, starch derivatives and cellulose derivatives such as methylcellulose, hydroxypropylcellulose, hydroxyethylcellulose, hydroxypropylmethylcellulose, furthermore polyvinyl alcohols, including partially saponified polyvinyl acetate with a degree of saponification of preferably at least 40%, in particular at least 60%, polyacrylamide, polyvinylpyrrolidone, polyethylene glycols, graft polymers of

Vinyl acetate and / or vinyl propionate on polyethylene glycols, one or both sides with alkyl, carboxyl or amino groups endgruppenverschlossene polyethylene glycols;

anionic water-soluble polymers whose polymer backbone has a multiplicity of carboxyl groups, sulfonic acid groups or sulfonate groups and / or phosphonic acid groups or phosphonate groups, for example carboxymethylcellulose, homo- and copolymers of ethylenically unsaturated monomers which are at least 20% by weight, based on the total amount of the monomers, at least one ethylenically unsaturated monomer which contains at least one carboxyl group, sulfonic acid group and / or phosphonic acid group in copolymerized form, and their salts, in particular the

Alkali metal and ammonium salts. In the aforementioned anionic

water-soluble polymers are usually in the aqueous usually bound to the polymer backbone sulfonic acid groups in the salt form, d. H. as sulfonate groups, and the phosphonic acid groups accordingly as

Phosphonate groups before. The counterions are then

typically alkali metal and alkaline earth metal ions such as sodium ions,

eg the chlorides; anionic or cationic modified starches; Examples of anionically modified starches are carboxymethylated starches and n-octenylsuccinyl-modified starch, for example as available as products from the company Cargill (CEmCap / CEmTex / CDeliTex n-octenylsuccinylated starches); Examples of cationically modified starches are starches modified with 2-hydroxy-3- (trimethylammonium) propyl groups, e.g. B. Starches which are obtainable by reacting conventional starches with A / - (3-chloro-2-hydroxypropyl) trimethyl ammonium chloride (CHPTAC), and which preferably have a substituent. degree of completion of 0.02 to 0.1. Examples of these are the products Hi-Cat 21370 from Roquette and Perlcore 134P from Lyckeby.

The anionic water-soluble polymers whose polymer backbone has a multiplicity of carboxyl groups, sulfonic acid or sulfonate groups and / or phosphonic acid or phosphonate groups include, for example:

Homo- and copolymers of monoethylenically unsaturated monocarboxylic acids having 3 to 6 carbon atoms (hereinafter monoethylenically unsaturated C3-C6 monocarboxylic acids) such. For example, acrylic acid and methacrylic acid, and their salts, in particular the alkali metal and ammonium salts;

Copolymers of monoethylenically unsaturated C 3 -C 6 -monocarboxylic acids with neutral monomers, such as, for example, vinylaromatics, such as styrene, C 1 -C 10 -alkyl esters of monoethylenically unsaturated C 3 -C 6 monocarboxylic acids and / or C 4 -C 6 -dicarboxylic acids, such as methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, propyl acrylate, Propyl methacrylate, n-butyl acrylate, n-butyl methacrylate, tert-butyl acrylate, tert-butyl methacrylate, n-hexyl acrylate, n-hexyl methacrylate, hydroxy ethyl ester, especially hydroxyethyl and hydroxypropyl esters of the aforementioned monoethylenically unsaturated C3-C6 monocarboxylic acids and / or C4-C6 Dicarboxylic acids such as hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate and hydroxypropyl methacrylate, and vinyl esters of aliphatic carboxylic acids such as vinyl acetate and vinyl propionate;

Homo- and copolymers of monoethylenically unsaturated sulfonic acids such as vinylsulfonic acid, styrenesulfonic acid, 2-acrylamide-2-methylpropanesulfonic acid, 2-acryloxyethanesulfonic acid, 2-Acryloxypropansulfonsäure etc. and their copolymers with the aforementioned neutral monomers, and the salts of the aforementioned homopolymers and copolymers , in particular the alkali metal and ammonium salts;

Homo- and copolymers of monoethylenically unsaturated phosphonic acids such as vinylphosphonic acid, 2-acrylamido-2-methylpropanphosphon- acid, 2-Acryloxyethanphosphonsäure, 2-Acryloxypropanphosphonsäure etc. and their copolymers with the aforementioned neutral monomers, and the salts of the aforementioned homo- and copolymers, especially the alkali metal and ammonium salts;

wherein the proportion of the neutral comonomers in the aforementioned copolymers usually will not exceed a proportion of 80% by weight, in particular 70% by weight, based on the total amount of the monomers constituting the copolymer.

To the anionic water-soluble polymers whose polymer backbone a variety

In particular, sulfonate groups also count

water-soluble copolyesters, the aromatically bound sulfonic acid or sulfonate groups in an amount of 0.3 to 1, 5 mmol / g, in particular 0.5 to

1, 0 mmol / g polyester, and their salts, in particular their Alkalime- tall- and ammonium salts, wherein the water-soluble copolyesters are preferably composed of:

i) 6 to 30 mol%, based on the total amount of components i), ii), and iii), of at least one aromatic dicarboxylic acid having at least one sulfonate group, and which is preferably selected from

5-sulfoisophthalic acid or its salts, in particular the sodium salt of sulfoisophthalic acid, or their ester-forming derivatives;

ii) optionally one or more aromatic dicarboxylic acids which have no sulfonyl groups and which are preferably selected from terephthalic acid and isophthalic acid and mixtures thereof, or their ester-forming derivatives;

iii) optionally one or more aliphatic or cycloaliphatic dicarboxylic acids, or their ester-forming derivatives;

iv) 95 to 105 mol%, based on the total amount of components i), ii), and iii), one or more aliphatic diols such as. For example, ethylene glycol,

1, 2-propanediol, 1, 3-propanediol, 1, 2-butanediol, 1, 4-butanediol,

1, 5-pentanediol, 2,4-dimethyl-2-ethylhexane-1,3-diol, 2,2-dimethyl-1,3-propanediol, 2-ethyl-2-butyl-1,3-propanediol, 2- Ethyl 2-isobutyl-1,3-propanediol, 2,2,4-trimethyl-1,6-hexanediol, especially ethylene glycol, 1,3-propanediol, 1,4-butanediol or 2,2-dimethyl-1,3 propanediol (neopentyl glycol),

wherein the total amount of components ii) and iii) 70 to 94 mol%, based on the total amount of components i), ii) and iii), wherein the components i), ii), iii) and iv) in the rule at least 99% by weight of all ester-forming constituents of the polyester (based on the components contained in the polyester). Such water-soluble copolyesters are known, for example, from US Pat. No. 6,521,679, to the disclosure of which reference is hereby made in its entirety. Common nonionic emulsifiers are z. B. C2-C3-alkoxylated, especially ethoxylated mono-, di- and tri-alkylphenols (degree of ethoxylation of 3 to 50, alkyl: CA to C12) and C2-C3-alkoxylated, in particular ethoxylated fatty alcohols (degree of ethoxylation of 3 to 80; : Cs to C36). Examples include the Lutensol® A grades (C12 to C fatty alcohol ethoxylates, degree of ethoxylation from 3 to 8), Luten sol® AO grades (C13 to cis oxo alcohol ethoxylates, degree of ethoxylation from 3 to 30), Lutensol® AT grades ( C16 to Cis fatty alcohol ethoxylates, degree of ethoxylation from 1 to 80), Lutensol® ON grades (C10 oxo alcohol ethoxylates, degree of ethoxylation from 3 to 1 liter) and the Lutensol® TO grades (C13 oxo alcohol ethoxylates, ethoxylation level from 3 to 20) BASF SE.

Typical anionic emulsifiers are the salts of amphiphilic substances which have an anionic functional group, eg. As a sulfonate, phosphonate, sulfate or The phosphate group. These include, for example, the salts, in particular the alkali metal and ammonium salts of alkyl sulfates (alkyl radical: Cs to C12), the salts, in particular the alkali metal and ammonium salts of amphiphilic compounds containing a sulfated or phosphated oligo-C 2 -C 3 -alkylene oxide group, in particular have a sulfated or phosphated oligoethylene oxide group, such as, for example, the salts, in particular the alkali metal and ammonium salts of sulfuric monoesters of ethoxylated alkanols (degree of ethoxylation from 2 to 50, in particular 4 to 30, alkyl radical: C10 to C30, in particular C12 to Cie) the salts, in particular the alkali metal and ammonium salts of sulfuric monoesters of ethoxylated alkylphenols (degree of ethoxylation from 2 to 50, alkyl radical: C ₄ to C 12), the salts, in particular the

Alkali metal and ammonium salts of Phosphorsäurehalbestern ethoxylated alkanols (degree of ethoxylation of 2 to 50, especially 4 to 30, alkyl: C10 to C30, especially C12 to Cie) the salts, in particular the alkali metal and ammonium salts of Phosphorsäurehalbestern ethoxylated alkylphenols (degree of ethoxylation of 2 to 50 , Alkyl radical: C ₄ to C 12), the salts, in particular the alkali metal and ammonium salts of alkylsulfonic acids (alkyl radical: C 12 to Cie), the salts, in particular the alkali metal and ammonium salts of alkylarylsulfonic acids (alkyl radical: C9 to Cie), and the salts, in particular the alkali metal and ammonium salts of Alkylbiphenylethersulfonsäu- ren (alkyl radical: C6 to Cie) such. For example, the product sold under the name Dowfax® 2A1.

Suitable cationic emulsifiers are generally a C6-C18-alkyl, C1-C10-alkylaryl or heterocyclic radical-containing cationic salts, for example primary, secondary, tertiary or quaternary ammonium salts, alkanolammonium salts, pyridinium salts, imidazolinium salts, oxazolinium salts, morpholinium salts, thiazolines salts and salts of amine oxides, quinolinium salts, isoquinolinium salts, tropylium salts, sulfonium salts and phosphonium salts, in particular their sulfates, methoxides, acetates, chlorides, bromides, phosphates, hexafluorophosphates and the like. Examples include dodecylammonium acetate or the corresponding sulfate, the sulfates or acetates of the various 2- (N, N, N-trimethylammonium) ethyl paraffinsäureester, N-Cetylpyridiniumsulfat, N-Laurylpyridiniumsulfat and N-cetyl- Ν, Ν, Ν-trimethylammonium sulfate, N-dodecyl-N, N, N-trimethylammonium sulfate, N-octyl-Ν, Ν, Ν-trimethylammonium sulfate, N, N-distearyl-N, N-dimethylammonium sulfate and the gemini-surfactant N, N '- (lauryldimethyl) ethylenediamine disulfate, ethoxylated tallow fatty alkyl-N-methylammonium sulfate and ethoxylated oleylamine (for example Uniperol® AC from BASF SE, about 12 ethylene oxide units).

In a preferred embodiment of the invention, the aqueous dispersion contains at least one neutral protective colloid, in particular a neutral, OH-group-bearing protective colloid, optionally in combination with one or more emulsifiers, preferably anionic or nonionic emulsifiers, in particular anionic emulsifiers containing a sulfate or sulfonate group. examples for neutral OH-bearing protective colloids are polysaccharides, e.g. For example, water-soluble starches, starch derivatives and cellulose derivatives such as methylcellulose, hydroxypropyl cellulose, hydroxyethylcellulose, hydroxypropylmethylcellulose, carboxymethylcellulose se, further polyvinyl alcohols, including partially saponified polyvinyl acetate with a degree of saponification of preferably at least 40%, in particular at least 60%. In particular, the neutral OH-bearing protective colloid is selected from polyvinyl alcohols, including partially hydrolyzed polyvinyl acetates having a saponification degree of preferably at least 40%, especially at least 60%. The preparation of the dispersions of biodegradable polyester can be carried out in analogy to that in the earlier patent application PCT / EP201 1/054471 method. Here, a composition of the polyester, which is usually at least 99% by weight of the polyester or a blend of the polyester with a different polymer and optionally one or more surface-active substances, at a temperature above the melting temperature or the softening temperature of the polyester or of the blend is introduced into an aqueous dispersion medium, which usually contains at least one surface-active substance, and the resulting aqueous emulsion is quenched. As a rule, the introduction of the composition of the polyester into the aqueous dispersing medium takes place in a mixing device which has at least one rotor-stator mixer.

In this process, the thermoplastic polyester, in the case of an amorphous polyester at a temperature above the softening point of the polyester or in the case of a crystalline or partially crystalline polyester above the melting point of the polyester, is introduced into the aqueous dispersing medium. In the case of amorphous polyesters, the softening temperature is understood to mean the temperature which corresponds to the glass transition temperature, as can be determined, for example, by means of differential scanning calorimetry (DSC) according to ASTM D 3418 or preferably according to DIN 53765 or by dynamic mechanical analysis (DMA). The melting temperature is understood to mean the temperature that leads to a

Melting or softening of the polyester leads and can be determined in a conventional manner by means of differential scanning calorimetry (DSC) according to DIN 53765 or differential thermal analysis (DTA). By an amorphous polyester is meant a polyester that is less than

1 wt .-% crystalline areas. A crystalline or a partially crystalline polyester is understood as meaning a polyester which has more than 1% by weight, in particular at least 5% by weight, of crystalline regions. The degree of crystallinity of a polyester can be determined in a manner known per se by X-ray diffractometry or by thermochemical methods such as DTA or DSC in a manner known per se. The rotor-stator mixers used for the production of the aqueous dispersion of the biodegradable polyester are familiar to the person skilled in the art and basically include all types of dynamic mixers in which a high-speed, preferably rotationally symmetrical rotor in cooperation with a stator forms one or more workspaces essentially annular in shape. In these work areas, the mix is exposed to strong shear and shear stresses, which often prevail in the annular gaps strong turbulence, which also favor the mixing process. In operation, the rotor-stator device is operated at a relatively high speed of typically 1000 to 20,000 rpm. This results in high peripheral speeds and a high shear rate, whereby the emulsion is exposed to high shear and shear stresses, which lead to an effective division of the melt and thus to a very effective emulsification. The rotor-stator mixers include, for example, sprocket dispersers, annular gap mills and colloid mills.

Preference is given to those rotor-stator mixers which have means for generating cavitation forces. Such means may be projections arranged on the rotor and / or stator side which project into the mixing chamber and which have at least one surface whose surface normal has a tangential component, such as pins, teeth or knives or coaxial rings with radially arranged slots. Preferably, the rotor-stator mixer on the rotor side at least one rotationally symmetrically arranged sprocket and / or at least one rotationally symmetrical ring with radial slots (tooth spaces) on. Such devices are also referred to as Zahnkranzdispergatoren or Zahnkranzdispergiermaschinen. In particular, the rotor-stator mixer both rotor side and stator on at least one rotationally symmetrical sprocket and / or ring with radial slots (tooth spaces), wherein the rotor and stator side arranged sprockets / rings are arranged coaxially and mesh to form an annular gap.

In a particularly preferred embodiment, the rotor-stator mixer is a Zahnkranzdispergiermaschine having a conical stator with a concentric frusto-conical recess and a likewise concentric conical rotor, wherein the rotor protrudes into the frustoconical working chamber of the stator, that an annular working space is formed in which rotor and stator side teeth protrude, each in the form of one or more, for. B. two, three or four rotor side and one or more, z. B. one, two, three or four stator-side coaxial sprockets are respectively arranged on the rotor and the stator, that the sprockets offset mesh. Such devices are known to the person skilled in the art, for example, from DE 10024813 A1 and US 2002/076639 and are described, for example, by the company Cavitron Verfahrenstechnik v. Chem. Hagen & Funke GmbH, Sprockhövel, Germany. As a rule, the composition of the polyester is mixed with the aqueous dispersing medium at a temperature above the softening point of the polymer. For this purpose, the composition of the polyester is usually heated to a temperature above the softening temperature and fed to the mixing device, preferably continuously. To the same extent, the required amount of aqueous dispersing medium, preferably continuously supplied to the mixing device. The amount of dispersing medium is usually chosen so that the desired solids content of the dispersion is adjusted. However, it is also possible to use the dispersing medium in a larger amount and then to concentrate the dispersion obtained. It is likewise possible first to prepare a more concentrated dispersion and to dilute it with further dispersant and / or water. The mass ratio of polymer fed to the total amount of aqueous dispersing medium is typically in the range of 1:20 to 1.2: 1, often in the range of 1:10 to 1: 1, 1, and more preferably in the range of 1: 3 to 1: 1. With continuous addition of polymer and aqueous dispersion medium, the mass ratio of the supplied material flows in the aforementioned ranges. In the case of a multistage addition of dispersing medium, the mass ratio of polymer fed to the total amount of aqueous dispersing medium fed in the first to the penultimate stage can also be up to 4: 1 or up to 2.3: 1. Preferably, the supply of polymer and aqueous dispersing medium occurs at a constant rate of addition, ie the mass ratio of thermoplastic polymer and dispersing medium is constant during the process or does not deviate more than 10% from the preselected mass ratio.

The introduction of the composition of the polyester in the aqueous dispersing medium is typically carried out at a temperature of at least 5 K, often at least 10 K and in particular at least 20 K, z. In the range of 5 to 150 K, often in the range of 10 to 100 K and in particular in the range of 20 to 80 K above the melting or softening temperature of the composition. This temperature is also referred to below as the mixing temperature. As a rule, the introduction of the composition into the aqueous dispersion medium at a temperature of at most 300 ° C, z. B. in the range of 50 to 300 ° C, often 60 to 250 ° C and especially 100 to 200 ° C.

Due to the comparatively high mixing temperature, the introduction of the composition into the aqueous dispersion medium usually takes place at a pressure above atmospheric pressure, generally at a pressure in the range from 1 to 50 bar, frequently 1, 1 to 40 bar, in particular in the range of 1, 5 up to 20 bar.

The mixing process can be in one or more, z. B. two, three, four or five stages are performed, wherein at least one stage in a rotor-stator mixer is carried out. In a multi-stage process, preferably all stages are carried out in rotor-stator mixers.

In a first embodiment of the invention, the mixing takes place in one stage, i. H. the mixing device comprises a rotor-stator mixer. In this case, the composition and dispersing medium are generally supplied to the rotor-stator mixer in the amounts required for the preparation of the dispersion. For this purpose, it has proven useful to heat the dispersant prior to feeding to the desired mixing temperature or a temperature of at least 20 K below the mixing temperature, preferably to a temperature in the range of +/- 20 K of the mixing temperature.

In a second, preferred embodiment of the invention, the mixing takes place in several stages, ie in a mixing device, the more, z. B. two, three, four or five, in particular three or four, serially interconnected rotor-stator mixer. It has proven useful in the first stage, ie in the first rotor-stator mixer to give the composition of the polyester and a subset of the dispersing medium and there at a temperature above the melting or softening temperature of the composition with the subset of the aqueous dispersing medium mix. The partial amount of the dispersing medium added to the first stage is usually from 10 to 60% by weight, in particular from 15 to 40% by weight, based on the total amount of the dispersing medium introduced into the mixing device. The introduction of the composition into the subset of the aqueous dispersion medium is typically carried out at a temperature of at least 5 K, often at least 10 K and in particular at least 20 K, z. In the range of 5 to 150 K, often in the range of 10 to 100 K and in particular in the range of 20 to 80 K above the melting or softening temperature of the composition. In general, the mixing temperature in the first rotor-stator mixer will be a maximum of 300 ° C, and is z. B. in the range of 50 to 300 ° C, often 80 to 250 ° C and especially 100 to 200 ° C. For this purpose, it has been proven that fed into the first rotor-stator mixer subset of dispersant before feeding to the desired mixing temperature or a temperature of at least 20 K below the mixing temperature, preferably to a temperature in the range of +/- 20 K of To heat the mixing temperature. The aqueous dispersion obtained in the first rotor-stator mixer is then transferred to another rotor-stator mixer where it is mixed with a further portion or the remainder of the dispersing medium. The second rotor-stator mixer, one or more, z. B. one or two, follow other rotor-stator mixer, wherein the resulting in the second rotor-stator mixer dispersion in or optionally further rotor-stator mixer (s) (z), z. B. the third rotor-stator mixer, with the remainder or a further subset of the aqueous dispersion medium are mixed. The temperature at which the dispersion obtained in the first rotor-stator mixer is mixed with further dispersion medium in the second rotor-stator mixer can be adjusted to the temperature. in the first rotor-stator mixer or above or below it. Preferably, it is below the temperature in the first rotor-stator mixer. In particular, it has proven useful if the mixing temperature in the first of the series-connected rotor-stator mixer at least 20 K, preferably at least 30 K, z. B. 20 to 200 K, in particular 30 to 120 K above the temperature in the last of the serially interconnected rotor-stator mixer. In particular, the temperature in the last of the serially interconnected rotor-stator mixer is at least 5 K, in particular at least 10 K, z. B. 5 to 200 K, in particular 10 to 150 K below the melting or softening temperature of the composition.

In a preferred embodiment of the invention, the composition of the polyester and the aqueous dispersion medium will be fed simultaneously, preferably continuously and in particular at a constant volume rate, to the rotor-stator mixer or the rotor-stator mixers and the dispersion removed to the same extent ,

However, it is also possible in an upstream step to mix the composition of the polyester with the aqueous dispersion medium to obtain a primary emulsion at a temperature above the melting or softening temperature of the composition of the polyester and to supply this mixture to the rotor-stator mixer , This upstream step is preferably carried out in a kneader or extruder. The pre-emulsion thus obtained is then fed to the rotor-stator mixer (s). Preferably, the preemulsion is maintained at a temperature above the melting or softening temperature of the composition of the polyester.

The initially obtained aqueous emulsion of the polymer in the aqueous dispersing medium, which is obtained in the mixing device, is then, d. H. after leaving the mixer, quenched, d. H. cooled rapidly to a temperature below the softening temperature of the composition of the polyester to avoid agglomeration of the polymer particles in the emulsion. The quenching can be carried out in a conventional manner, for example by suitable cooling devices and / or by dilution with cooled dispersant. Preferably, the emulsion should not dwell for more than 20 seconds, especially not more than 10 seconds, after leaving the mixing apparatus at temperatures above the melting or softening temperature of the polymer. In the case of a mixing device which has a plurality of rotor-stator mixers connected in series, the quenching can also take place in the second and possibly further rotor-stator mixers.

The dispersions suitable for use according to the invention may consist solely of water, optionally surface-active substance and those dispersed in water Consist of polymers. But it can also contain other additives, eg. As fillers, antiblocking agents, dyes, leveling agents, thickeners for adjusting the rheology or wetting aids. These additives will usually constitute no more than 50% by weight, based on the total solids content of the dispersion. As a rule, these additives are added to the dispersion after dispersion of the polymer (s). In one embodiment of the invention, the aqueous dispersion of the polyester contains up to 50% by weight, based on the total solids content of the dispersion, of one or more platelet-shaped pigments. Examples of platelet-shaped pigments are talc, clay or mica (mica). Preferred is talc. Preferred form factors (length to thickness ratio) are greater than 10.

The present invention also relates to a process for producing a barrier coating on paper or board, comprising applying at least one aqueous dispersion of at least one biodegradable polyester as defined herein to at least one surface of the paper or board.

The application of the aqueous dispersion (s) of the at least one biodegradable polyester (hereinafter polymer dispersion) can be carried out in a manner known per se. The application of the polymer dispersion can be carried out, for example, by applying to the support material, d. H. Paper or board which applies polymer dispersion by means of suitable coating machines. If web-like materials are used, the polymer dispersion is usually applied from a trough over an applicator roll and leveled with the aid of an air brush. Other ways to apply the polymer dispersion, succeed z. Example with the aid of the reverse gravure process, with spraying or with a roller blade or with other coating methods known in the art. The carrier substrate is provided on at least one side with a coating, d. H. It can be coated on one side or on both sides. Preferred application methods for paper and board are curtain coating, air knife, bar brushing or knife coating. After application of the aqueous polymer dispersion to the carrier substrates, volatile constituents, especially water, are evaporated. For this purpose, for example, when working continuously, the material can pass through a dryer channel, which can be equipped with an infrared irradiation device. Thereafter, the coated and dried packaging material is usually passed over a cooling roll and finally wound up.

In general, the polymer dispersion is applied to the carrier in an amount of at least 1 g / m ² , often at least 2 g / m ² , especially at least 3 g / m ² and especially at least 5 g / m ² , calculated as solids per m ^{2 of} the coated surface, applied to the carrier substrate. The polymer dispersion is preferably applied to the carrier in an amount of from 2 to 50 g / m ² , in particular from 3 to 40 g / m ² , especially from 5 to 30 g / m ² , calculated as solid per m ^{2 of} the coated surface, applied to the carrier substrate. The resulting coating thickness is accordingly on average at least 1 μηη, often at least 2 μηη, in particular at least 3 μηη and especially at least 5 μηη, z. B. in the range of 2 to 50 μηη, in particular 3 to 40 μηη, especially 5 to 30 μηη.

A specific embodiment of the invention relates to a method for coating cardboard, in particular cardboard, which is at least partially, as a rule, at least 30% by weight (wt .-%, based on total fiber mass), in particular at least 50 wt .-% or made entirely of mineral oil-loaded recycled paper. In this case, the polymer dispersion in a total amount (based on the total amount of the layers) of usually at least 2 g / m ² , often at least 3 g / m ² , especially at least 4 g / m ² and especially at least 5 g / m ² , calculated as solid per m ² , applied to the surface of the board surface to be coated. Preferably, the dispersion in a total amount in the range of 3 to 50 g / m ² , in particular 4 to 40 g / m ² , especially 5 to 30 g / m ² , calculated as solids per m ² , applied to the board surface to be coated , The coating thickness is accordingly on average at least 2 μηη, often at least 3 μηη, in particular at least 4 μηη and especially at least 5 μηη, z. B. in the range of 2 to 50 μηη, in particular 3 to 40 μηη, especially 5 to 30 μηη.

A further embodiment of the invention relates to a process for coating paper, in particular paper, which is at least partially, as a rule at least 30% by weight (% by weight, based on total fiber mass), in particular at least 50% by weight. or made entirely of mineral oil-loaded recycled paper. In this case, the polymer dispersion in a total amount (based on the total amount of layers) of generally at least 1 g / m ² , often at least 2 g / m ² , in particular at least 3 g / m ² , calculated as solids per m ² , on Preferably, the dispersion is brought in a total amount in the range of 1 to 30 g / m ² , in particular 2 to 25 g / m ² , especially 3 to 20 g / m ² , calculated as the solid per m ² , on the paper surface to be coated. The coating thickness is accordingly on average at least 1 μηη, often at least 2 μηη, in particular at least 3 μηη, z. B. in the range of 12 to 30 μηη, in particular 2 to 25 μηη, especially 3 to 20 μηη.

It has proven to be advantageous in this case if, in a first step, by applying the aqueous dispersion to a surface of the paper or cardboard, a first layer is produced and then preferably in at least one further step, for. B. in one, two, three or four further steps, in particular in one or two further steps, by applying the aqueous dispersion to the first layer obtained in the first step at least one further, arranged on the first layer layer. Between the individual steps can be drying steps be made. However, the individual coatings can also be applied wet-on-wet, ie no separate drying steps are carried out. This is usually done by first applying the polymer dispersion in a first step to the substrate, ie at least one surface of the paper or cardboard in the manner described above, optionally drying, and then coating the polymer dispersion on the coating thus obtained Surface of the substrate in the manner described above reapplies. This process can be repeated one or more times until the desired coverage is achieved. In this regard, the above applies. The application rate of the polymer dispersion is generally selected such that in the individual steps the application rate is at least 0.5 g / m ² , often at least 1 g / m ² , especially at least 2 g / m ² , especially at least 3 g / m ² and typically in the range of 1 to 30 g / m ² , especially 2 to 25 g / m ² , especially 2 to 20 g / m ² or 3 to 20 g / m ² , especially 2 to 12 g / m ² or 3 to 12 g / m ² , calculated as the solid per m ^{2 of} the coated surface. In this way, a coating is obtained which is made up of a plurality of layers arranged on top of one another, wherein a coating thickness results per layer in accordance with the solids discharge. The number of layers and the application amount per layer is naturally chosen so that the total amount of solid applied and thus the resulting coating thickness preferably in the range of 2 to 50 g / m ² , in particular 3 to 40 g / m ² , especially 5 to 30 g / m ² results. In the case of paperboard, the number of layers and the amount applied per layer is often chosen so that the total amount of solid applied and thus the resulting coating thickness preferably in the range of 3 to

50 g / m ² , in particular 4 to 40 g / m ² , especially 5 to 30 g / m ² , calculated as solids per m ² . In the case of paper, the number of layers and the amount applied per layer is frequently chosen so that the total amount of solid applied and thus the resulting coating thickness preferably in the range of 1 to 30 g / m ² , in particular 2 to 25 g / m ² , especially 3 to 20 g / m ² , calculated as solids per m ² .

With regard to the composition of the aqueous dispersion of the at least one polyester as well as with respect to preferred polyesters and the substrates, the same applies.

A preferred embodiment of the present invention also relates to a method for producing a barrier coating on paper or board in the manner described above, in which the paper or the cardboard at least in part, usually at least 30 wt .-% (wt. %, based on total fiber mass), in particular at least 50 wt .-% or completely made of mineral oil loaded recycled paper. In particular, the invention relates to such a method. where the paper or board is intended for food packaging. These include sales packaging, such as boxes or papers, but also consumer packaging, such as disposable tableware, z. As plates, cups or cups made of cardboard.

Coated paper or board obtainable by the method according to the invention is likewise an object of the present invention. In addition to a good barrier effect against non-volatile vegetable oils, vegetable fats and animal fats or oils, it also has a good barrier action against mineral oils, in particular against volatile mineral oils, ie. H. towards gas permeating mineral oils, especially those having 15 to 25 carbon atoms, z. B. harmful paraffin and naphthenic hydrocarbons and aromatic hydrocarbons. In addition, good blocking strengths are achieved, and papers coated according to the invention can be rolled up without sticking together.

The invention will be explained below with reference to examples. The polymer melts were I. Analysis ηο To determine the zero shear viscosity by dynamic viscosity measurements s determined at 180 ° C with oscillatory shear at low amplitude at shear rates in the range of 0.01 to 500 ^_1 and a thrust amplitude of 100 Pa viscosity curves, and from this, the zero shear viscosity ηο by Extrapolation to a shear rate of 0 s ^_1 determined. To determine the viscosity curves, a rheometer of the type "Dynamic

Stress Rheometer (DSR) "from the company Rheometrics with a plate-plate geometry (diameter 25 mm, gap 1 mm) used.

The determination of the shear viscosity of the polymer melt under the dispersing conditions was carried out by means of dynamic viscosity measurement of the polymer melts with a rotational rheometer (SR5) from Rheometrics at the temperature indicated in the examples.

The viscosity of the dispersing medium under the dispersing conditions was determined according to Brookfield with a MCR301 rotational rheometer of

Fa. Anton Paar GmbH at the temperature given in the examples, wherein the measurement was carried out up to a shear rate of 1000 / s and the viscosity was determined under dispersing conditions by extrapolation to the shear rate corresponding to the example.

The viscosity number was determined according to EN ISO 1628-1 at 25 ° C on a 0.5 wt .-% solution of the polymer in o-dichlorobenzene / phenol (1: 1 w / w). Molecular weights were determined by gel permeation chromatography (GPC) according to DIN 55672-1. The particle size distribution was determined on a 1 wt .-% dilution of the dispersion by light scattering at 25 ° C.

The Brookfield viscosity of the dispersions was determined at 20 ° C. according to DIN EN ISO 2555 using a Physika MCR Couette geometry CC 27 rotational viscometer.

Used polyester

Polyester 1: aliphatic-aromatic copolyester

Polybutylene terephthalate adipate, which was prepared as follows: 1095.2 g of terephthalate (47 mol%), 700 g of 1, 4-butanediol (65 mol%), 1 ml of glycerol (0.05% by weight, based on the polymer) were combined with 1, 1 ml

Tetrabutyl orthotitanate (TBOT) first mixed and heated to 160 ° C. The resulting methanol was distilled off within 1 h. After that, the

Boiler cooled to approx. 140 ° C. Subsequently, this was 929.5 g

Adipic acid (53 mol%), 700 g of 1,4-butanediol (65 mol%) and 1 ml of glycerol (0.05 wt%, based on the polymer) together with 1.04 ml of tetrabutyl orthotitanate (TBOT). The reaction mixture was heated to a temperature of 190 ° C, and at this temperature over a period of 1 h, the resulting

Distilled off water. Subsequently, the temperature was raised to 240 ° C and gradually evacuated. Excess 1,4-butanediol was distilled off in vacuo (<1 mbar) over a period of 1 h. The number average molecular weight of the resulting copolyester was at

21,000 g / mol, the weight-average molecular weight at 59,000 g / mol. The viscosity number VZ was 106. The zero shear viscosity no at 180 ° C was 136 Pa.s. The acid number was less than 1 mg KOH / g.

Polyester 2: aliphatic-aromatic copolyester

Polybutylene terephthalate adipate prepared as follows: 1388.5 g of terephthalate (55 mol%), 1000 g of 1, 4-butanediol (85 mol%), 1 ml of glycerol

(0.05 wt .-%, based on the polymer) were together with 1, 1 ml

Tetrabutylorthotitanate (TBOT) first mixed, and heated to 160 ° C, the resulting methanol was distilled off within 1 h. Thereafter, the kettle was cooled to about 140 ° C. Subsequently, this was added 854.9 g

Adipic acid (45 mol%), 523 g of 1,4-butanediol (45 mol%) and 1 ml of glycerol (0.05 Butanediol (45 mol%) and 1 ml of glycerol (0.05 wt .-%, based on the polymer) together with 1, 04 ml of tetrabutyl orthotitanate (TBOT). The reaction mixture was heated to a temperature of 190 ° C, and at this temperature, the resulting water was distilled off over a period of 1 h. Subsequently, the temperature was raised to 240 ° C and gradually evacuated. Excess 1,4-butanediol was distilled off in vacuo (<1 mbar) over a period of 1 h.

The viscosity number VZ was 91. The acid number was less than 1 mg KOH / g. Polyester 3: aliphatic copolyester

Polybutylene succinate sebacinate prepared as follows: 6.8 kg sebacic acid (5 mol%), 75.7 kg succinic acid (95 mol%), 79.1 kg 1, 4-butanediol (130 mol%), 298 g of glycerin (0.25% by weight, based on the polymer) were mixed and heated to 120 ° C. Subsequently, 1 1 g of tetrabutyl orthotitanate (TBOT) was mixed together and heated to 200 ° C. The resulting water was distilled off within 1 h. Thereafter, the kettle was cooled to about 140 ° C. Subsequently, 22 g of tetrabutyl orthotitanate (TBOT) were added. Subsequently, the temperature was increased to 250 ° C and gradually evacuated.

Excess 1, 4-butanediol was distilled off in vacuo (<5 mbar) over a period of 1 h.

The viscosity number VZ was 153. The zero shear viscosity no at 180 ° C was 271 Pa.s. The acid number was less than 1 mg KOH / g.

Preparation of the polyester dispersion

Dispersing Example 1

The rotor-stator mixer used was a 12-stage inline dispersing device, the device being provided with toothed ring-type shear elements.

Polyester 1 was continuously drawn through the hopper in an amount of 1, 2 kg / h in the single-screw extruder (Tech -ine E 16 T from Dr. Colin GmbH) and melted there at 155 ° C. The polymer melt was fed to the first stage disperser (4000 rpm). The shear rate was 12566 S ^-1 . The polymer viscosity at this shear rate was 35 Pa s.

At the same time, a 7% strength by weight aqueous solution of a partially saponified polyvinyl alcohol (Kuraray Poval 224E) containing 1% by weight of an anionic surfactant (Emulphor FAS 30 from BASF SE) having a solution viscosity of 0.038 Pa s was added to the in-line Dispersing device fed so that in the first and the fourth stage resulted in solids contents of 55% by weight and 45% by weight, respectively. In the tenth step, the solids content was adjusted to 43% by weight. The temperature in the first ten stages was 155 ° C; in the eleventh and twelfth stages the temperature was 130 ° C. The total residence time was 1.2 minutes. After leaving the last stage, the dispersion was quenched by means of a cooling bath to 20 ° C. The dispersion had a solids content of 43% by weight and an average particle diameter d32 = 1.6 μm.

Dispersing Example 2:

The rotor-stator mixer used was a 12-stage in-line dispersing device in which the device was provided with toothed ring-type shear elements.

The copolyester from Polymer Production Example 1 (ηο = 136 Pa.s) was continuously drawn through the hopper in an amount of 1, 2 kg / h in the single-screw extruder (Tech -ine E 16 T from Dr. Colin GmbH) and there at 155 ° C melted. The polymer melt was fed to the first stage disperser (4000 rpm). The shear rate was 12,566 sec ^_1. The polymer viscosity at this shear rate was 36 Pa s measured using a capillary rheometer Göttfert-Rheograph 2003. Simultaneously, a 7% strength by weight aqueous solution of a partially saponified polyvinyl alcohol (Kuraray Poval 224E) containing 1% by weight of an anionic surfactant contained (Emulphor FAS 30 BASF SE) with a solution viscosity of 0.038 Pa s in the in-line disperser fed so that in the first and fourth stage solid contents of 60 wt .-% and 50 wt .-% resulted. In the tenth step, the solids content was adjusted to 46% by weight. The temperature in the first ten stages was 155 ° C; in the eleventh and twelfth stages the temperature was 130 ° C. The total residence time was 1, 8 min. After leaving the last stage, the dispersion was quenched by means of a cooling bath to 30 ° C. The dispersion had a solids content of 46% by weight and an average particle diameter of d32 = 1.6 μπΊ.

Preparation of Coated Paper: The following experiments were carried out on a mini-plant coater of the company.

Bachofen & Meier performed. The machine has the following specification: Working width: 330 mm; Machine speed: 10 - 150 m / min; Unwinding: max. 600 mm dia; Core diameter: 70, 76 and 150 mm; Application system: roller; Drying: 6 drying hoods: air heater 47 kW, heater 14 kW; with a dosing system: roller scraper or rod squeegee.

Example 1 - Simple Coating on Cardboard The dispersion of Dispersing Example 1 was applied to the raw board (300 g / m ² Smurfit Kappa Gernsbach) in one pass with a roller scraper using the Mini Plant Coater. The machine speed was 50 m / min, the order quantity: 10 g / m ² (solid).

Example 2 - Double coating on raw board

The dispersion of Dispersing Example 1 was applied to the raw board (300 g / m ² Smurfit Kappa Gernsbach) in two passes with a roller scraper using the Mini Plant Coater. The machine speed was 50 m / min, the order quantity per pass 5 g / m ² (solid).

Example 3 - Simple coating on base paper Stora-Enso

The dispersion of dispersion example 1 was applied to raw paper (Stora-Enso cable 37 g / m ² LWC) in one pass using a rod wiper using the Mini Plant coater. The machine speed was 50 m / min, the order quantity: 10 g / m ² (solid).

Example 4 - Simple coating on raw paper Magnostar

The dispersion of dispersion example 1 was applied to raw paper (Magnostar base paper 58 g / m ² ) in one pass using a rod wiper using the Mini Plant coater. The machine speed was 50 m / min, d application rate: 10 g / m ² (solid).

Example 5 - Double Coating on Raw Paper Magnostar The dispersion of Dispersing Example 1 was applied to raw paper (Magnostar base paper 58 g / m ² ) in two passes with a rod wiper using the Mini Plant Coater. The machine speed was 50 m / min, the order in the passage 5 g / m ² (solid) in the second round 4 g / m ² (solid).

Testing the barrier properties

Barrier test against gaseous mineral oil constituents (test method 1)

9 ml of hexane are placed in a container with a sponge and closed with a lid which has an opening and a sealing ring (inner diameter 63 mm). The opening is tightly closed with the barrier material under test, with the barrier material not coming into contact with the hexane-soaked sponge. It is the weight loss of the measured at different times. The weight loss is a measure of the gas phase through the barrier material escaping hexane and thus a measure of the quality of the barrier effect against gaseous mineral oil components. The weight loss in grams is converted to 1 m ^{2 of} paper surface and then expressed as g / m ² d (per day). The results are shown in the following Table 1.

Barrier test against edible oil / oleic acid (Test Example 2)

The barrier properties of the uncoated papers / cardboards and the papers / cardboards coated with the polyester dispersions were investigated according to the "Oil Penetration Test". For this purpose, the coated paper side was wetted with 2 ml of oleic acid. Then the paper was stored at 60 ° C for a certain time. Then, the back side of the coated paper was visually inspected for the extent of staining at various times. 100% means a complete penetration, 0% no penetration.

nb = not determined

Claims

claims:

Use of an aqueous dispersion of at least one biodegradable polyester in the form of a coating for improving the barrier properties of packaging material made of paper or cardboard to mineral oils.

Use according to claim 1, wherein the packaging material has been at least partially made of mineral oil loaded recycled paper.

Use according to claim 1 or 2, wherein the packaging material is intended for the packaging of food.

Use according to one of the preceding claims, wherein the coating has a coating thickness of 2 to 50 g / m ² .

Use according to one of the preceding claims, wherein the coating has at least two layers arranged on one another.

Use according to claim 5, wherein each of the layers has a coating thickness in the range of 1 to 30 g / m ² .

Use according to any one of the preceding claims, wherein the proportion of biodegradable polyester in the total solids content of the polyester dispersion is at least 30% by weight.

Use according to one of the preceding claims, wherein the biodegradable polyester is selected from the group of aliphatic polyesters, aliphatic copolyesters, aliphatic-aromatic copolyesters and mixtures thereof.

Use according to one of the preceding claims, wherein the polyester is essentially composed of:

a) at least one dicarboxylic acid component A, consisting of

a1) at least one aliphatic or cycloaliphatic dicarboxylic acid or its ester-forming derivatives or mixtures thereof and a2) optionally one or more aromatic dicarboxylic acids which have no sulfonic acid group, or their ester-forming derivatives or mixtures thereof

a3) optionally one or more aromatic dicarboxylic acids which have at least one sulfonic acid group, or their ester-forming derivatives or mixtures thereof; b) at least one diol component B which is selected from aliphatic and cycloaliphatic diols and mixtures thereof;

c) optionally one or more further bifunctional compounds C which react with carboxylic acid or hydroxyl groups to form bonds; and

d) optionally one or more compounds D which have at least three functionalities which react with carboxylic acid or hydroxyl groups to form bonds;

wherein the molar ratio of component A to component B is in the range of 0.4: 1 to 1: 1 and components A and B at least 80 wt .-% of

Make out polyester.

Use according to claim 9, wherein the polyester is substantially composed of:

a) at least one dicarboxylic acid component A, consisting of

a1) 35 to 90 mol% of at least one aliphatic or cycloaliphatic dicarboxylic acid or its ester-forming derivatives or mixtures thereof and

a2) 10 to 65 mol% of one or more aromatic dicarboxylic acids or their ester-forming derivatives or mixtures thereof;

a3) 0 to 5 mol% of one or more aromatic dicarboxylic acids having at least one sulfonic acid group, or their ester-forming derivatives or mixtures thereof, wherein the mol% of the components a1), a2) and a3) to 100 mol - add%;

b) 98 to 102 mol%, based on the total amount of components a1) and a2), of at least one diol component B, which is selected from aliphatic and cycloaliphatic diols and mixtures thereof;

c) 0 to 2% by weight, based on the total weight of the polyester, of one or more further bifunctional compounds C which react with carboxylic acid or hydroxyl groups to form bonds; and

d) 0 to 2 wt .-%, based on the total weight of the polyester, one or more compounds D, which have at least 3 functionalities which react with carboxylic acid or hydroxyl groups to form bonds.

Use according to any one of the preceding claims, wherein the number average molecular weight of the polymer is in the range of 5,000 to 1,000,000 daltons.

Use according to any one of the preceding claims wherein the weight average molecular weight of the polymer is in the range of 10,000 to 5,000,000 daltons. 13. A method for producing a barrier coating on paper or board by applying at least one aqueous dispersion of at least one biodegradable polyester as defined in any one of claims 1 or 7 to 12 to at least one surface of the paper or board, wherein in a first step by applying the aqueous dispersion to a surface of the paper or cardboard, a first layer is produced and subsequently produced in at least one further step by applying the aqueous dispersion to the first layer obtained in the first step at least one further layer arranged on the first layer. 14. The method of claim 13, wherein in each step, the polyester dispersion is applied in an amount such that a coating thickness per layer in the range from 1 to 30 g / m ² results.

15. The method according to any one of claims 13 or 14, wherein the polyester dispersions are applied in the steps in an amount to a total coating thickness in the range of 2 to 50 g / m ² results.

16. A method according to any one of claims 13 to 15, wherein the proportion of biodegradable polyester in the total solids content of the polyester dispersion is at least 30% by weight.

17. The method according to any one of claims 13 to 16, wherein the biodegradable polyester is a polyester according to any one of claims 8 to 16. 18. The method according to any one of claims 13 to 17, wherein the paper or the cardboard was made at least partially from mineral oil loaded recycled paper.

19. The method according to any one of claims 13 to 18, wherein the coated paper or the coated cardboard as packaging material for the packaging of

Food is determined.

20. Coated paper or board, obtainable according to one of claims 13 to 19.