DE102009005640A1 - Thermoplastic molding mass, useful for preparing molded parts, comprises matrix phase from polysaccharide, and inhibitor that reduces at least one of the chain degradation of polysaccharide ester during the thermoplastic processing - Google Patents

Abstract

Plasticizer-free thermoplastic molding mass (I) comprises a matrix phase from at least one polysaccharide, and at least one inhibitor that reduces at least one of the chain degradation of polysaccharide ester during the thermoplastic processing. Independent claims are included for: (1) preparing (I) comprising homogeneously mixing the inhibitor with the matrix phase; (2) molded parts produced by (I); and (3) preparing molded parts comprising thermoplastic processing of (I) by extrusion, preferably a profile and film extrusion, injection molding, injection blow molding, pressing, or melt spinning.

Description

The The present invention relates to a thermoplastic molding composition, which has a matrix phase of a polysaccharide ester and free of plasticisers. The molding compound contains in addition at least one inhibitor that inhibits molecular degradation during prevents the thermoplastic processing of the molding compound. The thermoplastic processing of said molding material leads so to products with unusually high strength, rigidity and heat resistance. Likewise, the concerns Invention a method for producing such molding compositions and From these molding compounds produced moldings and a corresponding Production method. Use find the moldings as high-strength and / or highly stressed construction components, as plates, films, Bristles, monofilaments or fibers.

Polysaccharide esters, such as. As starch esters or cellulose esters, unlike most petroleum-based polymers, such as polypropylene, polyethylene, polyamides, etc. are not melt-processable without the addition of plasticizers by conventional methods such as extrusion or injection molding. For starch itself, the term thermoplastic starch (TPS) was coined. TPS denotes starch compounds which contain plasticizers, such as water, glycerol, sorbitol or the like, and are therefore thermoplastically processable ( EP 0 397 819 ). To achieve thermoplastic processability of starch esters plasticizers are also usually added here z. B. glycerol triacetate ( US 5,869,647 ).

Celluloseester, u. a. Cellulose acetate (CA), cellulose butyrate (CB), cellulose acetate butyrate (CAB), which is commercially available for thermoplastic processing, injection molding in particular, also contain plasticizers, which are mostly based on phthalic acid esters. significant Manufacturers are Eastman Co. with the Tenite and Albis range Plastics GmbH with Cellidor, whereby the products by different Plasticizer content in the range of 5% to 30% differ. Lower Plasticizer contents are offered on longer-chain esters, z. B. CAB, which due to their molecular structure a lighter Processing, compared with shorter-chain, z. B. CA, allow.

The softeners for cellulose esters conventionally used in the art include o-, m-, p-phthalic acid, benzoic acid, trimellitic acid, benzenesulfonic acid, aliphatic dicarboxylic acids (glutaric acid, adipic acid, azelaic acid, sebacic acid), aliphatic monocarboxylic acids (saturated fatty acids C ₂ -C ₁₈ , Oleic acid, linoleic acid, linolenic acid, ricinoleic acid), acrylic acid, phosphoric acid and citric acid.

• • Mono-, Di- und Triester,
• • bei den Di- und Triestern auch Verbindungen mit gemischten Estergruppen,
• • bei den Triestern speziell Glycerintriacetat und Glycerintripropionat,
• • Glyceride mit Esterrestgruppen, die zu den linearen und verzweigten aliphatischen Alkylgruppen sowie den olefinischen Restgruppen gehören, mit C₂-C₃₆-Kohlenstoffatomen in den Alkylketten.

Aus der Gruppe der Citrate:

• • Mono-, Di- und Triester,
• • bei den Di- und Triestern auch Verbindungen mit gemischten Estergruppen.

Aus der Gruppe der Phthalate:

• • Dimethylphthalat,
• • Diethylphthalat,
• • Dibutylphthalat,
• • Butylbenzylphthalat,
• • Ethylenglycolmonoethylphthalat, etc.,

Ester der Trimelittsäure:

• • Trimethyltrimellitat,
• • Triethyltrimellitat,
• • Tri-(2-ethylhexyl)trimellitat, etc.

Aliphatische Dicarbonsäureester

• • wie Di-(2-ethylhexyl)azelat etc.

Aus der Gruppe der Phosphorsäureester:

• • Tributylphosphat,
• • Tributoxyethylphosphat,
• • Triphenylphosphat,
• • Tricresylphosphat,
• • Cresyldiphenylphosphat,
• • 2-Ethylhexyldiphenylphosphat etc.

Ester der Ricinolsäure:

• • 12-Hydroxyacetyl-9-octadecensäuremethylester etc.

In particular, plasticizers known to the art for cellulose esters are understood as meaning the following substance groups:

From the group of glycerides:

• • mono-, di- and triesters,
• • in the diesters and triesters also compounds with mixed ester groups,
• In the triesters especially glycerol triacetate and glycerol tripropionate,
• • Glycerides with ester residue groups belonging to the linear and branched aliphatic alkyl groups and the olefinic residue groups, with C ₂ -C ₃₆ carbon atoms in the alkyl chains.

From the group of citrates:

• • mono-, di- and triesters,
• • in the diesters and triesters also compounds with mixed ester groups.

From the group of phthalates:

• • dimethyl phthalate,
• Diethyl phthalate,
• Dibutyl phthalate,
• • butyl benzyl phthalate,
• Ethylene glycol monoethyl phthalate, etc.,

Esters of trimellitic acid:

• • trimethyl trimellitate,
• Triethyl trimellitate,
• Tri (2-ethylhexyl) trimellitate, etc.

Aliphatic dicarboxylic acid esters

• • such as di- (2-ethylhexyl) azelate etc.

From the group of phosphoric acid esters:

• Tributyl phosphate,
• Tributoxyethyl phosphate,
• Triphenyl phosphate,
• Tricresyl phosphate,
• Cresyl diphenyl phosphate,
• 2-ethylhexyldiphenyl phosphate etc.

Esters of ricinoleic acid:

• • 12-hydroxyacetyl-9-octadecenoic acid methyl ester etc.

The the prior art use of plasticizers allows the thermoplastic processing of polysaccharide esters on an industrial scale, however, just by the plasticizing Effect, the mechanical properties of the final product (extrudate or injection molded part) down. This is evident when looking at maximums commercial cellulose-based products (starch-based lie underneath). For the product Biograde 200C from FKur be with tensile strengths in the range of 80 MPa and Tensile Moduli of 3.4 GPa described such maximum values. Otherwise usual Values are far below and are in the range of 40 MPa or 1.5 GPa. Another disadvantage of plasticized systems exists in that plasticizer by which they are characterized as plasticizers high mobility have a migration tendency in the finished molded part, which can lead to embrittlement of the product. The disadvantages mentioned are achieved by the invention overcome thermoplastic bio-based material.

outgoing It was an object of the present invention to provide moldings, which do not have the said disadvantages in the prior art, d. H. are thermoplastically processable and yet high strength and have rigidity.

These The object is achieved by the molding compound having the features of the claim 1, the process for its preparation with the features of the claim 7, the molding with the features of claim 11 and the method for the production of the molded part with the features of claim 14 solved. In claim 15 according to the invention Uses indicated. The other dependent claims show advantageous developments.

According to the invention provided a polysaccharide-based thermoplastic molding composition, which comprises a matrix phase of at least one polysaccharide ester, in which at least one inhibitor substance is contained. The inventive Molding material contains no plasticizer.

Surprisingly, simple chemical substances, referred to herein as inhibitors or inhibitor substances, which, after addition to the matrix phase of cellulose esters, exhibit an effect on thermoplastic processing without producing an apparent softening effect in the end product. As a result, unusually high strengths (for example tensile strengths of 203 MPa) and stiffnesses (for example tensile moduli of 8.4 GPa), for example. B. in injection-molded specimens reached (see the examples below). The inhibitor substances are characterized in that they prevent or limit the degradation of the molecular chains in the matrix phase such that the molecular weight after processing is above that which results without said addition. As further explained in the Examples, the reduction of the weight average molecular weight from 40% for a system without inhibitors to, for example, 14% for that with suitable inhibitors is reduced (see Example 6). In addition, the mobility of the inhibitors in the finished molding is negligible, as evidenced by the lack of plasticizing effect. Further advance Parts of the material according to the invention result from the lack of plasticizers in terms of thermal stability. Thus, even when compared to a conventional system having a very low plasticizer content (10% triacetin in cellulose acetate), the heat distortion resistance is increased by 45 K, if, instead of the plasticizer, 0.17% by weight NaCl is added as an inhibitor during processing in a suitable manner. This achieves a heat deflection temperature (drop in the dynamic bending modulus at 10 Hz to 1 GPa) of 195 ° C.

Preferably the polysaccharide ester is a cellulose ester from the group of cellulose acetates, cellulose butyrates and / or Butyrates.

Of the Cellulose ester preferably has a degree of substitution (DS) of 1.7 to 3, more preferably from 2.3 to 2.7.

When Inhibitors in the sense of the invention are suitable for all substances, a chain degradation during thermoplastic processing Prevent or limit the molding composition. As suitable Potassium chloride and urea have been found. Being particularly suitable have also been found substances containing Na ions, such as sodium hydroxide, sodium chloride or sodium sulfate.

Of the Weight fraction of the cellulose ester in the molding composition is preferably between 99.9999 and 90% by weight, preferably between 99.99 and 95 wt .-% and particularly preferably between 99.9 and 97 wt .-%.

Of the Weight fraction of the at least one inhibitor substance, based on the total molding compound is preferably between 0.0001 and 10% by weight, preferably between 0.001 and 5% by weight, and especially preferably between 0.1 and 3 wt .-%.

According to the invention as well as a process for the preparation of the plasticizer-free thermoplastic A molding composition as described above, provided the at least one inhibitor substance under the action of mechanical Shear forces with the cellulose ester matrix is homogeneously mixed. In addition to the direct addition of the inhibitor substances, a proves special embodiment of the invention Method advantageous in which an aqueous solution of the inhibitor is prepared and the cellulose esters with this Soaked solution and then dried become. Before the mechanical shear becomes a more homogeneous output distribution achieved the inhibitor substances in the cellulose esters.

The Mixing is preferably carried out at temperatures between 0 ° C. and 450 ° C, preferably between 100 ° C and 350 ° C and more preferably between 150 ° C and 300 ° C.

A preferred embodiment of the preparation of the material according to the invention is carried out as follows:
Cellulose acetate powder with a degree of substitution of 2.63 is dried under vacuum at 80 ° C for 24 h. A certain amount (see examples) of the modifier substance is premixed with the cellulose acetate for about 5 minutes by means of a fast rotating mixer. Subsequently, the resulting mixture is homogenized with a kneader at temperatures ranging from 180 to 300 ° C and rotational speeds between 50 and 350 rotations per minute (rpm). Mixing times are in the range between 5 and 60 minutes, preferably between 10 and 30 minutes. For further homogenization, an extrusion is carried out on a co-rotating twin-screw extruder at temperatures between 200 and 350 ° C and a screw speed between 10 and 350 rpm. The extrudate is comminuted with a commercial strand pelletizer and injection molded. The cylinder temperatures are between 210 and 250 ° C and mold temperatures between 80 and 140 ° C.

For soluble inhibitor substances (see examples) are suitable also the following variant of the invention Process. A defined amount of the inhibitor is in a suitable Solvent, preferably water, under the action of mechanical Shear forces completely solved. Subsequently a defined amount of the cellulose esters is added and a homogeneous dispersion, also under the action of mechanical forces, produced. This is followed by drying of the resulting premix under vacuum at 50 ° C. Further processing takes place as described above by kneading, extrusion and injection molding.

According to the invention also provided moldings, which from the previously described Molding material can be produced.

The moldings according to the invention preferably have a tensile strength of at least 100 MPa, preferably at least 130 MPa, more preferably at least 150 MPa and particularly preferably at least 175 MPa. These tensile strengths are reflected on a test rod DIN EN ISO 527-1 type 5A determined at 23 ° C and 50% relative humidity.

Furthermore, the moldings of the invention have a tensile modulus of at least 5 GPa, preferably at least 6 GPA, more preferably at least 7 GPa, and most preferably at least 8 GPa. These tensile moduli are simulated on a test rod DIN EN ISO 527-1 type 5A determined at 23 ° C and 50% relative humidity.

Farther is a method for producing the above-described molded part provided in which a molding composition, as described above was, is processed thermoplastically. The thermoplastic processing takes place here preferably by extrusion, in particular profile and film extrusion, injection molding, injection blow molding, pressing, or melt spinning.

use find the moldings of the invention as a high strength and / or highly stressed construction component, as a plate, foil, Bristle, monofilament or fiber in the field of transport, Industrial equipment, mechanical and plant engineering, household appliances, Tank construction, medical technology, electrics and electronics.

Based The following examples are intended to illustrate the invention Subject to be explained in more detail, without this restrict to the specific embodiments shown here to want.

example 1

Cellulose acetate powder L60 / 90 from Eilenburg with a DS determined by nuclear magnetic resonance of 2.63 is pre-dried overnight at 80 ° C in a vacuum oven. With a fast-rotating kitchen mixer, a premix is prepared containing 3.1 g of urea and 100 g of pre-dried cellulose acetate powder and stored in a polyethylene bag is sealed in overnight. The premix is homogenized in a kneader W 350 E from Brabender for 20 min at 230 ° C. and a speed of 150 rpm. After discharge and comminution of the compound, it is further homogenized in a co-rotating twin-screw extruder (Haake Minilab) at 230 ° C. and 200 rpm, discharged and granulated (granulator SGS 25-E4 from Scheer). Subsequent injection molding takes place on a Haake Minijet at a cylinder temperature of 230 ° C and a mold temperature of 110 ° C. There are test rods after DIN EN ISO 527-1 type 5A subsequently produced at 23 ° C and 50% relative humidity in an air-conditioned laboratory on a Zwick 1445 testing machine DIN EN ISO 527-1 being checked.

Example 2

As Example 1, with only 0.5 g of sodium hydroxide powder instead of urea.

Example 3

175 mg of sodium chloride (3 mmol Na in NaCl) is demineralized in 200 ml Water dissolved with stirring. Subsequently are 100 g of cellulose acetate powder L60 / 90 from. Eilenburg in The solution is introduced and mixed by mixing a homogeneous Dispersion produced. This dispersion will last for at least Dried at 50 ° C under vacuum for 24 h. With the so produced Premix is processed as in Example 1, but without the use a kneader, d. H. the premix is extruded directly.

Example 4

As Example 3, with only 224 mg of potassium chloride (3 mmol K in KCl) instead of sodium chloride.

Example 5

As in Example 3, only with 213 mg of sodium sulfate (3 mmol Na in Na ₂ SO ₄ ) instead of sodium chloride.

Example 6

As Example 3, with only 120 mg sodium hydroxide (3 mmol Na in NaOM) instead of sodium chloride.

Example 7

For For comparison purposes, 100 g of cellulose acetate powder L60 / 90 of Fa. Eilenburg introduced into demineralized water, as described mixed, dried and processed as in Example 3.

In Table 1, the mechanical properties of inventive materials according to Examples 1 to 6 compared to Comparative Example 7 without inhibitor, compared to the commercially available material Biograde 200C (FKuR GmbH) containing a plasticizer and the unprocessed cellulose acetate powder, and determined weight average Molar mass M _W shown. The determination of the mechanical characteristics was carried out according to DIN EN ISO 527-1 , Test specimen type 5A.

The Determination of the molecular weight was carried out by gel permeation chromatography (GPC). In this case, 22 mg of the thermoplastic to be examined processed molding material or the thermoplastic processed starting ester in 4 ml of dichloromethane / methanol (90:10 vol.%: vol.%) at room temperature dissolved and stored for 24 h. The actual measurement was done with conventional GPC (polystyrene standards) via an HPLC pump (Waters 515), an autosampler (Waters 717 plus), column oven and UV-Vis detector (Waters 2487) at one wavelength of 254 nm and a RI detector (Waters 2414) at 25 ° C. The column bank used was based on polystyrene divinylbenzene (Polymer Laboratories) with a precolumn (PL gel, 10 μm) and three subsequent columns (PL gel, 20 μm, MIXED-A).

As from the column "Molmassenabbau" becomes clear, the inhibitors used reduce the degradation by 41% the sample without inhibitor addition up to 14% in Example 6 The mechanical values are impressively demonstrated that the inventive Molded parts have significantly better strength and stiffness.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• EP 0397819 [0002]
• US 5869647 [0002]

Cited non-patent literature

• - DIN EN ISO 527-1 Type 5A [0021]
• - DIN EN ISO 527-1 Type 5A [0022]
• - DIN EN ISO 527-1 type 5A [0026]
• - DIN EN ISO 527-1 [0026]
• - DIN EN ISO 527-1 [0033]

Claims (15)

Plasticizer-free thermoplastic molding composition containing a matrix phase of at least one polysaccharide ester and at least a chain degradation of the polysaccharide ester during the thermoplastic processing at least reducing inhibitor. Molding composition according to claim 1, characterized that the at least one polysaccharide ester comprises at least one cellulose ester, preferably cellulose acetate, cellulose butyrate and / or cellulose acetate butyrate. Molding composition according to one of the preceding claims, characterized in that the polysaccharide ester has a degree of substitution (DS) from 1.7 to 3, preferably from 2.3 to 2.7. Molding composition according to one of the preceding claims, characterized in that the at least one inhibitor is selected is selected from the group consisting of alkali metal salts, in particular sodium hydroxide, sodium chloride, Sodium sulfate and potassium chloride, as well as urea. Molding composition according to one of the preceding claims, characterized in that the proportion by weight of the matrix phase, based on the molding composition, between 99.9999 to 90 wt .-% preferred between 99.99 and 95 wt.%, more preferably between 99.9 and 97 wt .-% is. Molding composition according to one of the preceding claims, characterized in that the weight proportion of the at least one Inhibitor, based on the molding composition, between 0.0001 to 10 wt .-%, preferably between 0.01 and 5 wt .-%, more preferably between 0.1 and 3 wt .-% is. Process for the preparation of a plasticizer-free thermoplastic molding composition according to any one of the preceding claims, wherein the at least one inhibitor is homogeneous with the matrix phase is mixed. Method according to claim 7, characterized in that that the at least one inhibitor with the matrix phase under the action is homogeneously mixed by mechanical shear forces. Method according to claim 7, characterized in that that an aqueous solution of the at least one inhibitor is prepared, the polysaccharide ester with this solution soaked and then dried. Method according to one of the two preceding claims, characterized in that the mixing at temperatures between 0 ° C and 450 ° C, preferably between 100 ° C and 350 ° C, more preferably between 150 ° C and 300 ° C is performed. Molded part, producible from a molding compound after a of claims 1 to 6. Molded part according to the preceding claim, characterized by a tensile strength of at least 100 MPa, preferably at least 130 MPa, more preferably at least 150 MPa, more preferably at least 175 MPa, measured on a test rod according to DIN EN ISO 527-1 type 5A at 23 ° C and 50% relative humidity. Molding according to one of the two preceding claims, characterized by a tensile modulus of at least 5 GPa, preferably at least 6 GPa, more preferably at least 8 GPa on a test rod according to DIN EN ISO 527-1 type 5A at 23 ° C and 50% relative humidity. Process for producing a molded article according to one of claims 11 to 13, wherein a molding compound according to a of claims 1 to 6 thermoplastic, in particular by Extrusion, in particular profile and film extrusion, injection molding, Injection blow molding, pressing, or melt spinning is processed. Use of a molding according to one of the claims 11 to 13 as a high-strength and / or highly stressed construction component, as a plate, foil, bristle, monofilament or fiber in the fields Transport, Industrial Equipment, Machinery and Plant construction, household appliances, container construction, medical technology, Electrics and electronics.