WO2014201480A1

WO2014201480A1 - New environmentally friendly method for producing sponges and sponge cloths from polysaccharides

Info

Publication number: WO2014201480A1
Application number: PCT/AT2014/000121
Authority: WO
Inventors: Gregor Kraft; Gert Kroner; Thomas Röder
Original assignee: Lenzing Ag
Priority date: 2013-06-19
Filing date: 2014-06-13
Publication date: 2014-12-24
Also published as: AT514472B1; AT514472A1

Abstract

The invention relates to a direct dissolving method in sodium hydroxide for producing porous shaped bodies that contain α(1→3) glucan as a structure-forming substance, and to the porous shaped bodies thus produced.

Description

New environmentally friendly process for producing sponges and sponges from polysaccharides

The present invention relates to a process for the production of spongy moldings, which are prepared by means of a direct dissolving process in sodium hydroxide from a (1 -> 3) -glucan.

State of the art

The production of sponge structures by the viscose process has been known for decades. As starting material from renewable raw materials recoverable polysaccharides, especially cellulose, are used. Alternative polysaccharides, such as the (deacetylated) chitin described in JP2007197649 (A), play only a very minor role.

From a safety point of view, the viscose process is problematic mainly because of the use of large amounts of highly flammable, toxic carbon disulfide, which are used to convert cellulose into alkali-soluble xanthate. In the course of the regeneration of cellulose it comes to the formation of sulfur-containing reaction and

By-products, including H ₂ S and CS ₂ , for their separation and

Recovery technologically and technically complex plant aggregates are needed. For sensitive applications, for example, for contact with food, additional measures for the reduction of

Total sulfur content of cellulosic sponge structure,

for example, as described in EP1693407 (A2), immediately following the manufacturing process oxidation treatment required.

Notwithstanding the disadvantages described above, the viscose process is still the only commercially used process for the production of artificial cellulose sponges. Alternative methods like that

Amine oxide method (CN101569757 (A), AT502363 (A1), US7189667 (B1), JPH1 1279323 (A)) or method using ionic liquids as direct solvent for cellulose (CN101792538 (A), WO2008087026 (A1)) As far as the applicant is aware, despite extensive research and development, no large-scale implementation has taken place until today.

From an ecological as well as from an economic point of view for the production of artificial cellulose sponges is particularly suitable

Direct dissolving method using aqueous sodium hydroxide solution as

Solvent. Conventional cellulosic starting materials such. B. Chemical pulps are only partially soluble due to their relatively high degree of polymerization in sodium hydroxide solution. By pre-switching corresponding

structure-changing activation steps, such as the

Steam explosion (EP147634 (A2)) or the hydrothermal

(WO2002022924 (A1), EP918101 (A1)) or enzymatic (WO2001096402 (A1), FI980008 (A)) pretreatment, the solubility of the cellulosic material used can be improved. Other possibilities are the addition of solubility-improving additives, such as urea, thiourea or zinc oxide, in the dissolving process. Thus, the CN102504327 (A) describes the

Preparation of a cellulose sponge by dissolving pretreated

Sisal hemp wastes in aqueous, urea-containing caustic soda at temperatures of -12 to -20 ° C. After the addition of cotton and sodium sulfate as a pore-forming agent, the cellulose is ripened and introduced into a

coagulating bath, which also contains sodium sulfate in addition to sulfuric acid, regenerated at about 60 ° C. According to CN101143941 (A)

Composite sponges of cellulose and soybean protein by

Freeze-drying corresponding, for example, crosslinked with glutaraldehyde solutions in aqueous urea-NaOH systems and subsequent neutralization with acetic acid are prepared.

No. 6,129,867 (A) deals in great detail with the production of sponges from cellulose dissolved in aqueous sodium hydroxide solution. to

To improve the solubility, the cellulosic starting material may be subjected to a pretreatment, in particular a steam explosion or microfibrillation. According to the invention, however, the complete solution of the cellulose used is not a condition. In presence

Sufficient amounts of undissolved cellulose can according to the US6129867 (A) dispensing with the addition of natural or synthetic fibers to improve the mechanical properties of cellulosic sponges. Subsequently, the cellulose solution is mixed with at least one pore-forming agent. As possible pore-forming substances are mentioned solids which melt under the precipitation conditions, sublimate or dissolve (eg ice or salt hydrates such as the sodium sulfate decahydrate, also called Glauber's salt, with melting points below 90 ° C.), furthermore solids or liquids which release a gas, polyelectrolytes or foaming bulking agents. Optionally, the addition of additives, including pigments for coloring, biocides or fungicides to the

Cellulosic sponges give additional, functional properties.

The cellulosic mass loaded with pore formers is according to the

US6129867 (A) by any method, such as by filling

Moldings, by extrusion by means of a nozzle or by coating of substances by means of rollers, processable. Of particular importance in the context of the invention is the gelation of the cellulose after deformation. This can be effected by temperature change and / or by adding suitable substances, such as cellulose derivatives. The conditions in the subsequent last step of the process described must be chosen so that the cellulose is not only precipitated, but also to form the desired pore structure, such as by melting,

Sublimation, dissolution or chemical decomposition of the pore-forming

Component is coming. Preferably, this sub-process comprises immersing the gelled mass in acid, preferably in sulfuric acid with

Concentrations of 10 to 100 mg / L. While any existing pore-forming carbonates under these conditions spontaneously below

If the pore formation is to be achieved by melting of the mixture components, it is necessary to ensure that the neutralization baths are appropriately tempered. Acid treatment may involve further substeps such as precipitation of the cellulose with simultaneous melting of the pore former by hot water treatment or by heating without direct contact with heat transfer

Liquids, e.g. B. in a microwave oven, are connected upstream. Alternatively For example, it is also possible to precipitate the cellulose prior to introduction into the neutralization bath by treatment with saline or slightly basic solutions or by removal of the water by freeze-drying or evaporation.

According to US Pat. No. 6,129,867 (A), the last step when using Glauber's salt as a pore-forming agent is particularly simple. From the corresponding molding compositions can be washed by rinsing with water cellulosic

Sponge structures are obtained, wherein preferably first hot and then cold water is used as a washing liquid.

On the whole, US Pat. No. 6,129,867 (A) discloses a favorable and, compared to the viscose process, substantially more environmentally compatible process for the production of artificial sponge structures from cellulose. The disadvantage is that the cellulose material used is generally only partially dissolved by the aqueous sodium hydroxide solution. Undissolved portions, especially if they are unevenly distributed and / or of varying size, affect the visual appearance of the final product. In the presence of larger agglomerates, negative effects on the strength of the final product are likely.

The outlined in the above prior art method for

Activation of the cellulosic material used, such as, for example, the steam explosion, not only makes the overall process more expensive, but in most cases also leads to a reduction in the degree of polymerization of the cellulose. This is often reflected in a deterioration in the mechanical properties of the cellulose sponges produced.

The addition of solubility-improving substances, such as urea or zinc oxide, in the preparation of the solution requires additional process steps for the recovery of these substances from the precipitation, neutralization and washing liquids. US 7,000,000 describes fibers obtained by spinning a solution of polysaccharides consisting essentially of hexose repeat units linked via a (1-3) glycosidic linkages. These polysaccharides can be prepared by contacting an aqueous solution of sucrose with glucosyltransferase (GtfJ) isolated from Streptococcus salivarius (Simpson et al.

Microbiology, vol 41, pp 1451-1460 (1995)). "Substantially" in this context means that sporadia may occur occasionally within the polysaccharide chains where other binding configurations occur.These polysaccharides are to be considered for the purposes of the present invention as "a (1-> 3) -glucan ".

According to US Pat. No. 7,000,000, the a (1 -> 3) -glucan is to be derivatized, preferably acetylated. The solvent is preferably an organic acid, an organic halogen compound, a fluorinated alcohol or a

Mixture of such components. These solvents are expensive and expensive to regenerate.

task

The task was over this prior art in

spongy, d. H. porous moldings consisting of a glucose-containing polysaccharide and a process for their preparation for

To provide that do not have the above-mentioned problems (for example, use of large quantities of chemicals to improve the solubility, poor use, in particular poor mechanical properties).

The polysaccharide raw material should be cheap and that

Processing methods should be feasible economically and on existing installations without fundamental modifications.

Description of the invention The solution to the problem described above is a new one

Process for the preparation of a porous shaped body, the

Structure-forming substance (1 -> 3) contains glucan, which consists of the following

Steps consists of: a. Preparation of an alkaline, a (1 -> 3) -glucan-containing

polysaccharide; b. Addition of pore images, dyes and optionally further

Additives (e.g., biocides or reinforcing fibers), c. Shaping the mass (e.g., by extrusion on perforated

Endless belts or filling of molds), d. Coagulation and regeneration of the mass.

The process according to the invention is a direct dissolution process in sodium hydroxide solution. Thus, a shaped body having a sponge structure can be produced, wherein α (1 → 3) -glucan-containing sodium hydroxide solution instead of a

Cellulose xanthogenate is used

The devices suitable for carrying out these steps and

general process conditions, the skilled person can readily derive inventive step in principle from the Viscoseverfahren.

In the following, the term "sponge" can also be used for shaped bodies having a porous structure, and such a porous structure can therefore also be termed "sponge-like".

For the purposes of this invention, "structure-forming substance" is to be understood as meaning the homogeneous, solid material of the molding material surrounding the pores

Embodiments of the invention still contain reinforcing materials such as fibers or fabrics, but for the purposes of this invention these reinforcing materials should not be included in the structure-forming substance. The a (1-3) glucan can be prepared by contacting an aqueous solution of sucrose with glucosyltransferase (GtfJ) isolated from Streptococcus salivarius (Simpson et al., Microbiology, vol 41, pp 1451-1460 (1995) )).

In a preferred embodiment of the process according to the invention, the a (1-3) -glucan consists of at least 90% hexose units and at least 50% of the hexose units are linked by cx (1-> 3) -glycosidic bonds.

In the process according to the invention, the structure-forming substance contains between 20 and 100% by weight of a (1-3) -glucan. In addition to the a (1 - 3) -glucan, in step a. solution also contain cellulose. Pulp is preferably used as cellulosic raw material. But in principle, any other cellulosic raw material suitable for direct dissolving processes in caustic soda solution is also suitable.

In a preferred embodiment of the process according to the invention, the structure-forming substance contains 100% by weight of a (1-3) -glucan.

The concentration of the structure-forming substance in the polymer solution may be between 4 and 15% by weight; preferably 5.5 to 12 wt .-%. The concentration of sodium hydroxide in the polymer solution may be between 2 and 10% by weight; from 4.0 to 5.5% by weight are preferred.

The degree of polymerization of the cx (1-3) glucan used in the process according to the invention, expressed as weight average DP _W , can be between 200 and 2000; values between 800 and 1500 are preferred.

If necessary, before or after step b. a filtration and / or venting of the polysaccharide solution take place.

As a pore-forming agent, certain salts such as Glauber's salt, sodium or potassium chloride, magnesium or sodium sulfate, other readily soluble or meltable substances, including water-soluble polymers or at elevated temperatures soluble, gel-like particles, such as gelatin, propellant such. B. gas-forming substances such as aluminum powder or gases are used. The resulting pore structure and thus ultimately the density of the sponges obtained depend essentially on the particle size and the particle size distribution of the salts used. A preferred pore-forming agent is Glauber's salt.

The porous shaped body according to the invention may contain a reinforcing material to improve its properties. This

Reinforcing material may be made of fibers, for example

Short cut fibers, which are the polysaccharide solution in

inventive method are added. This gives a shaped body in which the reinforcing fibers are distributed throughout the structure-forming material.

Another embodiment of the invention is that

Polysaccharide solution applied to a sheet-like reinforcing material, preferably on a textile fabric, so that this reinforcing material surrounds the porous shaped body according to the invention substantially on its outer side. A variant of this embodiment is to apply the polysaccharide solution so that the planar

Reinforcing material is located inside the porous molding.

The textile fabric can be, for example, a dry or wet-laid paper or another nonwoven, but also a woven, knitted or knitted fabric. Basically, of course, foils or thicker, rigid plates of almost any materials as a flat

Reinforcement possible.

Combinations of several of the above-mentioned reinforcing materials in the same shaped body are possible and are included in the invention.

The invention also relates to a porous shaped body, as

structure-forming substance contains a (1- »3) -glucan. This shaped body can also be referred to as a sponge. The structure-forming substance contains between 20 and 100% by weight, preferably 100% by weight of a (1-3) -glucan.

In a preferred embodiment, at least 90% of the ct (1-> 3) -glucan consists of hexose units and at least 50% of the hexose units are linked by a (1- »3) -glycosidic bonds.

In a preferred embodiment, the shaped body contains cellulose as further structure-forming substance.

In a preferred embodiment, the inventive

Shaped body a reinforcing material, as already described above.

The shaped bodies according to the invention can be used as sponges or

Sponge cloths of all kinds are used.

In the following the invention will be described by way of examples. However, the invention is expressly not limited to these examples, but includes all other embodiments based on the same inventive concept

Examples

The degree of polymerization of the a (1-3) -glucans was determined by GPC in

DMAc / LiCI determined. In the following, the weight average of the

Degree of polymerization (DP _W ) indicated.

Example 1 :

An ot (1- »3) -glucan with a DP _W of 1000 was dissolved in sodium hydroxide solution and a solution containing 4.7% by weight of NaOH and 9% by weight of a (1-3-glucan was prepared. 1 100% by weight Glauber's salt, based on glucan content, was added to this polymer solution and mixed in. In addition, 15% by weight of lyocell fibers, based on glucan content, were added to the solution with a cut length of 4-5 mm. The sponge raw material was extruded on a fine-meshed grid, coagulated with hot water (97 ° C) and then with a

Sulfuric acid bath regenerated. During coagulation and regeneration, the Glauber's salt is partially melted and washed out. Thereafter, the sponge-like structure was washed and dried.

Example 2:

An a (1-3) glucan with a DP _W of 1000 was dissolved in sodium hydroxide solution and a solution of 4.5 wt.% NaOH and 8 wt.% Ct (1-3) glucan was prepared. This polymer solution was 800 wt .-% Glauber's salt, based on

Gluecangehalt, added and mixed. In addition, 15 wt .-% Lyocellfasern, based on Glücangehalt, were added with a cut length of 4-5 mm of the solution.

The sponge raw material was poured into a mold, coagulated with an acidic sodium sulfate solution (400 g / l Na 2 SO 4) and a temperature> 95 ° C and regenerated. During coagulation and regeneration, the Glauber's salt is partially melted and washed out. Thereafter, the sponge-like structure was washed and dried.

Example 3:

An a (1 → 3) -glucan having a DP _W of 1200 was dissolved in sodium hydroxide solution and a solution containing 4.5% by weight of NaOH and 8% by weight of a (1- »3) -glucan was prepared. 1000% by weight of Glauber's salt, based on glucan content, are added to this polymer solution and mixed in. In addition, 35 wt .-% Lyocellfasern, based on Glücangehalt, were added with a cut length of 4-5 mm of the solution.

The sponge raw material was extruded on a fine-meshed grid, coagulated with hot water (97 ° C) and then regenerated with glacial acetic acid. During coagulation and regeneration or the washing steps, the Glauber's salt is partially melted and washed out. Thereafter, the sponge-like structure was washed and dried.

Claims

Claims / Claims

1. A process for the preparation of a porous shaped body whose structure-forming substance contains a (1 - »3) -glucan, comprising the steps of: a. Preparation of an alkaline, a (1-3) glucan-containing polysaccharide solution,

b. Addition of pore images, dyes and optionally further additives,

c. Shaping the mass,

d. Coagulation and regeneration of the mass.

2. The method of claim 1, wherein the structure-forming substance contains between 20 and 100 wt .-%, preferably 100% a (1-3) glucan.

3. The method of claim 1, wherein the method is a direct dissolution method in caustic soda.

4. The method of claim 1, wherein the at least 90% of the a (1- »3) -glucan consists of hexose units and at least 50% of the hexose units are linked by a (1 ~ 3) -glycosidic bonds.

5. The method of claim 5, wherein the pore-forming agent is Glauber's salt

6. The method of claim 1, wherein the shaped body contains as further structure-forming substance cellulose.

7. The method of claim 1, wherein the polysaccharide solution reinforcing material in the form of fibers, preferably short cut fibers added.

8. The method according to claim 1, wherein the polysaccharide solution is applied to a sheet-like reinforcing material, preferably to a textile fabric.

9. porous shaped body, characterized in that it contains as structure-forming substance a (1 -> 3) -glucan.

10. Porous molding according to claim 9, wherein the structure-forming substance contains between 20 and 100 wt .-%, preferably 100 wt .-% a (1 -> 3) -Glucan.

1 1. Porous shaped body according to claim 9, wherein the a (1- »3) -glucan consists of at least 90% of hexose units and at least 50% the hexose units are linked by a (1-3) glycosidic bonds.

12. Porous shaped body according to claim 9, wherein the shaped body contains as further structure-forming substance cellulose.

13. Porous molding according to claim 9, wherein the shaped body a

Contains reinforcing material.

14. Porous molding according to claim 13, wherein the reinforcing material consists of fibers, preferably short cut fibers, and / or a textile

Sheet consists.