DE102007026166A1 - Thermoplastic shaping of polyvinyl alcohol for manufacturing granulates, foil, fibers or coating for use in pharmaceutical or cosmetic applications, involves accomplishing shaping in absence of extrusion additive - Google Patents

Abstract

Thermoplastic shaping involves accomplishing shaping at 150-240[deg] C in absence of extrusion additive, softeners, glycerin, starch, polyolefins, polypropylene, polymethylmetacrylate, polyvinylacetate, polyethylene glycols or thermoplastic polymers. The polyvinyl alcohol contains 5 wt.% of a volatile compound. The thermoplastic shaping takes place by extruding or injection molding. 0 to 0.5 wt.% of methanol content is present in polyvinyl alcohol after the thermoplastic shaping.

Description

The The present invention relates to a process for thermoplastic Shaping of polyvinyl alcohol in the absence of auxiliaries, usually in thermoplastic processing be used by polyvinyl alcohol, as well as with this method produced moldings such as granules.

Technical environment

Polyvinyl alcohol (PVA), formally a copolymer with vinyl acetate and vinyl alcohol units is considered to be non-thermoplastically processable. The reason for this is generally considered to be the decomposition temperature of about 180-200 ° C., which is significantly below the melting point of about 212-267 ° C. ( CA Finch, "Polyvinyl alcohol Properties and Applications", Wiley Verlag, 1973 ). However, in order to be able to process polyvinyl alcohol thermoplastically, auxiliaries such as plasticizers or other thermoplastic polymers (referred to below as extrusion aids) must be admixed so that the resulting composition has a melting temperature below the decomposition temperature.

State of the art

For the thermoplastic processing of polyvinyl alcohol with extrusion aids or additives a variety of publications are known. For example, reference may be made to the following, more recent patent applications: WO 2006/075174 (PVA with glycerol and propylene glycol), WO 2005/078032 (PVA with sorbitol, waxes, fatty acid esters), WO 2005/058569 (PVA with plasticizer for injection molding), WO 2006/032929 (PVA with extrudable starch), US 2000-629678 (PVA with thermoplastic elastomers), EP 1 559 323 (PVA with aliphatic polyamides), US 2006-0211804 (PVA with polyolefins) or WO 2005/065301 (PVA with creatine or other polymers).

These Publications all disclose the extrusion of polyvinyl alcohol-containing Mixtures with extrusion aids, but not the thermoplastic Processing of polyvinyl alcohol without such extrusion aids.

task

to Production of Moldings or Granules of Polyvinyl Alcohol however, the thermoplastic processing would be pure Polyvinyl alcohol desirable if extrusion aids disturb and z. B. undesirable from the molding migrate.

Surprisingly it was found that, contrary to the literature, polyvinyl alcohol also in pure form d. H. without extrusion aid thermoplastic is processable.

Presentation of the invention

object The present invention is therefore a process for thermoplastic Shaping of polyvinyl alcohol with a degree of hydrolysis of over 50 mol% and a viscosity of 0.1 to 30 mPas, thereby characterized in that the thermoplastic molding at a temperature from 150 to 240 ° C in the absence of extrusion aids takes place, as well as molded articles produced by this method or granules.

The inventive method is in the absence the usually added extrusion aid for the thermoplastic processing of polyvinyl alcohol such as plasticizer or other polymers performed.

When polymeric extrusion aids for the thermoplastic Processing of polyvinyl alcohol are z. B. all thermoplastic Polymers, especially starch, polyolefins, polyamides, Polymethyl methacrylate, polyvinyl acetals and / or polyethylene glycols used.

Particularly suitable plasticizers for PVA are aliphatic mono- or polyhydric alcohols, such as diols or triols, in particular glycerol or starch, and / or derivatives thereof, such as glycols (mono- or polyglycols or polyethylene glycols), as pure substance or mixture. In the process according to the invention, all compounds known to the person skilled in the art as plasticizers for PVA are to be avoided, ie also the compounds listed in the abovementioned patent literature, such as glycerol, propylene glycol, sorbitol, waxes, fatty acid esters, extrudable starch, thermoplastic elastomers, aliphatic polyamides polyolefins and / or creatine.

in the Processes according to the invention are preferably not d. H. 0% by weight (based on PVA) extrusion aids such as those mentioned Connections used.

Polyvinyl alcohols are prepared by hydrolysis of polyvinyl acetate in aqueous solution and therefore usually contain volatile components such as water, methanol, acetaldehyde and methyl acetate. In the context of the present invention, these compounds are not considered as extrusion aids in the amounts customary for commercially available PVA types. Accordingly, polyvinyl alcohols used according to the invention preferably contain 0-5% by weight, more preferably 0-2.5% by weight of volatile constituents such as the compounds mentioned (in each case based on the PVA used). The volatiles are based on DIN ISO 1625 as described in the examples.

With the method of the invention can Accordingly, polyvinyl alcohols having a methanol content of the polyvinyl alcohol after the thermoplastic molding of 0 to 0.50 wt.% Preferably 0 to 0.05 wt.%, And particularly preferably 0 to 0.01 wt.% become. Products of this type can be called methanol-free are and are for pharmaceutical or cosmetic applications z. B. suitable as a tablet coating.

One Another object of the invention is therefore the use of a Granules, a film, a two- or three-dimensional injection moldings or a coating made by thermoplastic molding of polyvinyl alcohol having a degree of hydrolysis of over 50 Mol% and a viscosity of 0.1 to 30 mPas, wherein the thermoplastic molding at a temperature of 150 to 240 ° C. in the absence of extrusion aids, in pharmaceutical or cosmetic applications. Preferably contains the material used has a methanol content of 0 to 0.5% by weight on.

Farther the polyvinyl alcohols used can be polymer residues contained in the manufacturing process, such as. As polyester or polyvinyl acetate. These compounds are - in the commercial for available PVA types - usual quantities in the context of the present invention not as extrusion aids considered. Accordingly, used according to the invention Polyvinyl alcohols preferably 0-1 wt.% Of polymeric impurities as the compounds mentioned (in each case based on the used PVA).

Of the has polyvinyl alcohol used according to the invention a degree of hydrolysis of over 50 mole percent (i.e., 50.1 to 100 Mol.%), In particular 70 to 100 mol.%, Preferably 85 to 100 mol.% or 90 to 100 mol.% On. The degree of hydrolysis is as in the examples described, determined.

The Viscosity of the polyvinyl alcohols used is between 0.1 to 30 mPas, preferably 1 to 15 mPas, particularly preferably 2 up to 10 mPas. The viscosity is as in the examples described on a 4% aqueous solution determined at 20 ° C.

The inventive method is carried out so that no or only a small chain degradation (eg by dehydration) or structure (eg by networking) takes place. This can be very simple by changing the viscosity, determined by the o. g. Procedures to be controlled. Preferably different the viscosity of a 4% aqueous solution (at 20 ° C) of the polyvinyl alcohol before and after the thermoplastic Shaping by a maximum of 5%, 4%, 3%, 2% or even in each case only at most by 1%.

The ash content of the polyvinyl alcohols used should be as low as possible in order to avoid degradation reactions during thermal loading by the process according to the invention. Preference is given to polyvinyl alcohols having an ash content (expressed in Na ₂ O) of max. 1% by weight, preferably max. 0.5 wt.% Used. The ash content is determined as the content of Na ₂ O as described in the examples.

in the methods of the invention can of course also several different polyvinyl alcohols in the form of a mixture be used, the entire mixture the o. g. properties must have. Suitable polyvinyl alcohols are under the trade name "Mowiol" Kuraray Europe GmbH available.

The thermoplastic molding in the invention Process is preferred by extrusion, kneading or injection molding carried out and includes in each case a thermal Load of the material.

This should be kept as short and / or low as possible. The mean residence time is preferably time of the PVA in the inventive method between 1 and 90 s., Preferably 1 to 60 s., In particular 1 to 45 s. or 1 and 30 s. The residence time is the time that the material is exposed to the temperatures mentioned. In an extrusion process, the transit time of the material in the extruder as residence time can be assumed for the sake of simplicity. The setting or determination of the residence time on an extruder is known to the skilled person and can, for. B. be influenced by appropriate screw geometry or speed of the extruder.

The Temperatures of the method according to the invention be 150 to 240 ° C, preferably 150 to 215 ° C. and in particular 150 to 210 ° C.

The method according to the invention is preferably carried out in such a way that that the resulting thermoplastically processed polyvinyl alcohol a low and acceptable for later use Yellowing YI. The yellowing YI becomes according to the method described in the examples determined as dimensionless size. Preferred is the yellowness Y of the polyvinyl alcohol before the thermoplastic molding 0-10, especially 0-5, more preferably 0-2. After the invention thermoplastic shape, the yellow value is preferred 0-50, more preferably 0-20 and especially 0-15.

One Another object of the present invention are granules, films, Fibers, two- or three-dimensional injection moldings or coatings prepared according to the invention Process in the absence of extrusion aids. As a substart for the coating according to the invention can be further polymers such as PET, polyolefins and / or PVC or glass or metals are used. As layer thickness of the coating 0.01 to 1 mm are possible.

The granules of the invention can be easily to a desired grain size and grain size distribution preferably by hot stamping, in particular by eccentric Granulation, knife roller granulation, cold cut, strand granulation or belt granulation. These procedures are out Well known in the art. The figure of the granules is according to the invention of subordinate Importance.

in the the process according to the invention is expediently carried out an extruder (single or twin screw extruder), multi-shaft kneader and / or kneader used.

Hereinafter, the present invention is illustrated by Examples and Comparative Examples, without this being intended to limit the inventive concept. The Polyvinylalkoholtypen used in this context (Mowiol ^®) are available from the company Kuraray Europe GmbH.

Test characteristics and test methods

Degree of hydrolysis (saponification degree)

The degree of hydrolysis (saponification degree) H indicates what percentage of the polyvinyl acetate base molecule is saponified to polyvinyl alcohol. From the content of residual acetyl groups and thus from the ester number EZ the degree of hydrolysis H is calculated according to the following formula and given in mol%: H = 100 · (100 - 0.1535 · EZ) / (100 - 0.0749 · EZ)

Esterzahl

The ester number (EZ) is the amount of KOH (in mg) which is consumed to neutralize the acid liberated from the ester by saponification in 1 g of substance. Determination method (based on DIN EN ISO 3681 ):

a) Partially hydrolyzed PVA types (up to approx. 95 mol%)

Approximately 1 g of PVA is weighed into a 250 ml round bottom flask and 70 ml distilled water and 30 ml of neutralized alcohol and heated to reflux. To The cooling is neutral with 0.1 N KOH against phenolphthalein posed.

After neutralization, 50 ml of 0.1 N KOH are added and boiled under reflux for 1 h. The excess liquor is heated in the heat against phenolphthalein as an indicator by means of 0.1 N HCl until the remaining Decolorization back titrated. Parallel to this, a blind test is carried out.

b) Fully hydrolyzed PVA types (from approx. 95 mol%)

a

= Verbrauch ml 0,1 n KOH

b

= Verbrauch ml 0,1 n KOH im Blindversuch

E

= Einwaage PVA (trocken)

In order to avoid absorption of carbon dioxide from the air in excess KOH, after neutralization of the PVA solution, only 25 ml of 0.1 N KOH are added and the solution is refluxed for 30 minutes. The still hot solution is mixed with 25 ml of 0.1 N HCl and titrated after cooling with 0.1 N KOH against phenolphthalein. Parallel to this, a blind test is carried out. Ester number (EZ) = (a * b) * 5.61 / E

a

= Consumption ml 0.1 n KOH

b

= Consumption ml 0.1 n KOH in blank test

e

= Weight PVA (dry)

residual acetyl content

The residual acetyl content is calculated from the ester number (EZ) as follows: Residual acetyl content (wt.%) = EC · 0.0767

viscosity

To DIN 51550 For example, viscosity is a measure of internal friction that occurs when two adjacent fluid layers shift. The unit of dynamic viscosity (η) in the international system of units (SI) is 1 Pa · s. The dynamic viscosity of PVA is measured using the Hoeppler falling ball viscometer ( DIN 53015 ) on a 4% aqueous solution.

Preparation of the solution

It a 4% solution is prepared by using the analytical balance, depending on the solids content, about 8.2 to 8.3 g of PVA to 0.01 g exactly weighed and stirred with stirring. B. in a beaker with 200 g of cold, deionized water (deionized water) are sprinkled. After heating for 30 minutes at 95 ° C leaves the Cool solution adds the vaporized Water and filtered if necessary through a 40 micron sieve.

The Pre-tempered to 20 ° C PVA solution is bubble-free filled into the measuring tube of the Höppler viscometer, which is connected to a thermostat (20 ° C). As soon as the solution the specified temperature of 20,0 ± 0,1 ° C has reached, you measure with a stopwatch the time that the ball needed to run through the measuring section between the ring marks. Thereafter, the solids content of the solution (3 g, 1 hour, 140 ° C) certainly. It must be between 3.85% and 4.15%, otherwise it must the solution will be recalculated.

evaluation

k

= Kugelkonstante nach Herstellerangaben

p1

= Dichte der verwendeten Kugel

p2

= Dichte der 4%igen Lösung (1.01 g/ml)

t

= Fallzeit der Kugel in Sekunden (Mittelwert aus 3 Messungen)

The dynamic viscosity (η) in mPas is calculated according to the following formula: (η) = k (p1-p2) · t

k

= Ball constant according to manufacturer's instructions

p1

= Density of the ball used

p2

= Density of the 4% solution (1.01 g / ml)

t

= Fall time of the ball in seconds (average of 3 measurements)

Recommended Sphere (for 4% solutions): up to 9 mPas sphere B, from 9 mPas ball C (according to manufacturer's instructions)

ash content

To determine the ash content, weigh 4.5-5.0 g of the sample in a nickel crucible. On the fast ashtray is ashed at about 700 ° C and then annealed at 800 ° C in a muffle furnace for 1 h. In 100 ml of hydrochloric acid c (HCl) = 0.015 mol / l are initially introduced into a titration beaker and the hot nickel crucible is introduced. After cooling, the nickel crucible is removed and rinsed with deionized water (demineralized water). The titroprocessor is titrated with sodium hydroxide solution. In the same way, 100 ml of hydrochloric acid solution are titrated as blank.

evaluation

• W (NaOH) = (VB) -VPr) * t (NaOH) * CTM * 3.099 / M

  W (NaOH)

  = Mass fraction of Na ₂ O ash in%

  VB1

  = Consumption of titrant the blank in ml

  Vpr

  = Consumption of titrant the sample in ml

  T (NaOH)

  = Titre of the sodium hydroxide solution

  CTM

  = Molar concentration the sodium hydroxide solution (0.1 mol / l)

  M

  = Initial weight of the examining sample in g

Volatiles

polyvinyl alcohol contains as volatile components mainly Water and organic solvents (methanol).

Determination method (based on DIN ISO 1625):

In a tared glass bowl with a diameter of approx. 5 cm approx. 2 g PVA are weighed and until constant weight dried at 105 ° C for about 3 h. After cooling in the desiccator is weighed back and the weight difference calculated as a percentage.

Volatile organic compounds, especially methanol content

The Determination of residual volatile organic compounds in PVA, in particular of methanol, is carried out by gas chromatography by means of so-called head-space analysis on internal calibration standards a Perkin Elmer GC 8500. The concentration of the individual sample components can take into account the correction factors from the signal surfaces of the volatiles and the standard substance. It can be methanol, Determine methyl acetate and acetaldehyde.

equipment

• Gas chromatograph, type 8500 with FID detector, Perkin Elmer
• Headspace sampler, type HS 101, Perkin Elmer
• PC with evaluation program Turbochrom
• Separation column, glass capillary DB-Wax, column length 30 m, inner diameter 0.25 mm, film thickness 0.25 μm
• Headspace sample vial 22 ml, analytical balance, stirrer with hot plate, dispenser 10 ml, glass syringe, 25 μl Type Hamilton 702N
• Solvent: deionized water

Implementation / Equipment Requirements

• Sample plate: 80 ° C
• Oven, isothermal: 40 ° C
• Injector: 150 ° C
• Detector (FID): 250 ° C
• Carrier gas: nitrogen

Sample preparation and measurement

A 5% PVA solution is prepared by weighing 0.5 g of PVA into a tared headspace vial (accuracy + 1-0.005 g) with magnetic core and making up to 10 g with deionized water. Then close the vial with an associated aluminum lid using pliers. The sample vial is now placed on a magnetic stirrer with hot plate (set to a temperature of 120 ° C) and the PVA brought to complete dissolution in about 30 minutes with stirring. you makes the vial cool to RT, place it in the autosampler and start the measurement.

Yellow YI

• Spectrocolorimeter UltraScan, Fa. HunterLab
• Hellma cuvettes 50 x 50 mm with Teflon lid

execution

fix a 4% aqueous PVA solution as for the measurement of viscosity described.

Measurement of total transmission YI

The The spectrocolorimeter and the printer are in the standardization mode "Total Transmission "(TTRAN) started measuring the 4% solution takes place relative to the transmission of a pure solvent (Deionized water) filled cuvette. In the measurement is on a bubble, streaks and dust-free filling the Pay attention to the measuring cuvette. The yellow value YI is from the meter displayed as dimensionless size.

example 1

• Zone 1: 80°C
• Zone 2: 125°C
• Zone 3 bis Zone 9: 200°C
• Zone 10: 210°C
• Düse: 210°C

On a Leistritz twin screw extruder type ZSE 27 GL 600 with 27 mm screw diameter, an L / D of 44 and 10 heating zones Mowiol 8-88 with the following temperature profile at 200 rpm and a throughput of 14 kg / h is extruded.

• Zone 1: 80 ° C
• Zone 2: 125 ° C
• Zone 3 to Zone 9: 200 ° C
• Zone 10: 210 ° C
• Nozzle: 210 ° C

The total of 5 kneading blocks type KB 5-2-30-30 are located at 20 D and 32 D. The remaining screw elements consist of conveying elements with different pitch. At 37 D, a vacuum degassing is used. By means of a 2-hole nozzle, strands with a diameter of 3 mm are produced. The strands obtained are homogeneous, free of bubbles and specks. The cooling takes place both by means of a lattice belt with air cooling and by cooling in a water bath with subsequent granulation. data analysis PVA Mowiol 8-88 Preserved granules dry matter 97.5% 98.8% viscosity 8.73 mPas 8.43 mPas methanol content 0.42% 0.009% Yellow YI 1.50 11,20

Example 2

On a Leistritz twin-screw extruder type ZSE 27 GL 600 with 27 mm screw diameter, an L / D of 44 and 10 heating zones Mowiol 18-88 with the following temperature profile at 200 rpm and one Throughput of 15 kg / h extruded.

Temperature profile of the extruder:

• Zone 1: 81 ° C, Zone 2: 126 ° C, Zone 3 and 4: 200, Zone 5: 210 ° C, Zone 6: 220 ° C, Zone 7 and Zone 8: 225 ° C, zone 9: 220 ° C, zone 10: 225 ° C, Nozzle: 220 ° C

The A total of 5 kneading blocks of type KB 5-2-30-30 are located at 20 D and 32 D. The remaining screw elements consist of Conveying elements with different pitch.

At 37 D, a vacuum degassing is used. By means of a 2-hole nozzle, strands with a diameter of 3 mm are produced. The strands obtained are homogeneous, free of bubbles and specks. The cooling takes place both by means of a lattice belt with air cooling and by cooling in a water bath with subsequent granulation. data analysis PVA Mowiol 18-88 Preserved granules dry matter 98.0% 98.9% viscosity 17.69 mPas 16.86 mPas methanol content 0.87% 0.015% Yellow YI 1.40 11,30

Example 3

• Zone 1: 80°C
• Zone 2: 120°C
• Zone 3 bis Zone 10: 190°C
• Düse: 200°C

On a Leistritz twin screw extruder type ZSE 27 GL 600 with 27 mm screw diameter, an L / D of 44 and 10 heating zones Mowiol 4-98 with the following temperature profile at 200 rpm and a throughput of 13.5 kg / h is extruded.

• Zone 1: 80 ° C
• Zone 2: 120 ° C
• Zone 3 to Zone 10: 190 ° C
• Nozzle: 200 ° C

The A total of 5 kneading blocks of type KB 5-2-30-30 are located at 20 D and 32 D. The remaining screw elements consist of Conveying elements with different pitch.

At 37 D, a vacuum degassing is used. By means of a 2-hole nozzle, strands with a diameter of 3 mm are produced. The strands obtained are homogeneous, free of bubbles and specks. The cooling takes place both by means of a lattice belt with air cooling and by cooling in a water bath with subsequent granulation. data analysis PVA Mowiol 4-98 Preserved granules dry matter 98.5% 98.9% viscosity 4.1 mPas 4.1 mPas methanol content 1.36% 0.019% Yellow YI 9.00 17,20

Example 4:

• Zone 1: 80°C
• Zone 2: 125°C
• Zone 3 bis Düse: 200°C

On a Leistritz twin screw extruder type ZSE 27 GL 600 with 27 mm screw diameter, an L / D of 44 and 10 heating zones Mowiol 10-98 with the following temperature profile at 200 rpm and a throughput of 13 kg / h is extruded.

• Zone 1: 80 ° C
• Zone 2: 125 ° C
• Zone 3 to nozzle: 200 ° C

The A total of 4 kneading blocks of type KB 5-2-30-30 are located at 22 D and 32 D. The remaining screw elements consist of Conveying elements with different pitch.

At 37 D, a vacuum degassing is used. By means of a 2-hole nozzle, strands with a diameter of 3 mm are produced. The strands obtained are homogeneous, free of bubbles and specks. The cooling takes place both by means of a lattice belt with air cooling and by cooling in a water bath with subsequent granulation. data analysis PVA Mowiol 10-98 Preserved granules dry matter 98.1% 98.9% viscosity 9.8 mPas 9.7 mPas methanol content 2.02% 0.015% Yellow YI 2.10 15.00

Comparative Example:

Analogous for example 4, instead of Mowiol 26-88, Mowiol 47-98 is tried extrude.

Mowiol 47-88 has a viscosity of about 47 mPas. The viscosity increase in the extruder was in the Due to decomposition, the selected screw geometry became so large that the attempt was interrupted by the torque protection shutdown.

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

• - WO 2006/075174 [0003]
• WO 2005/078032 [0003]
• WO 2005/058569 [0003]
• WO 2006/032929 [0003]
• US 2000-629678 [0003]
• EP 1559323 [0003]
• US 2006-0211804 [0003]
• WO 2005/065301 [0003]

Cited non-patent literature

• CA Finch, "Polyvinyl alcohol Properties and Applications", Wiley Verlag, 1973 [0002]
• - DIN ISO 1625 [0012]
• - DIN EN ISO 3681 [0030]
• - DIN 51550 [0035]
• - DIN 53015 [0035]

Claims (10)

Process for the thermoplastic molding of polyvinyl alcohol having a degree of hydrolysis of more than 50 mol% and a viscosity of 0.1 to 30 mPas, characterized in that the thermoplastic molding is carried out at a temperature of 150 to 240 ° C in the absence of extrusion aids. Method according to claim 1, characterized by Absence of plasticizers, glycerol, starch, polyolefins, Polyamides, polymethyl methacrylate, polyvinyl acetals, polyethylene glycols and / or thermoplastic polymers. Method according to claim 1 or 2, characterized that the viscosity of the polyvinyl alcohol before and after thermoplastic molding differs by more than 5%. Method according to one of claims 1 to 3, characterized in that the proportion of volatile compounds of the polyvinyl alcohol used is at most 5% by weight. Method according to one of claims 1 to 4, characterized in that the yellowness YI of the polyvinyl alcohol after the thermoplastic molding is 0 to 50. Method according to one of claims 1 to 5, characterized in that the thermoplastic molding by extrusion or injection molding. Method according to one of claims 1 to 6, characterized in that the average residence time of the polyvinyl alcohol at the temperature of 150 to 220 ° C for 1 to 90 seconds is. Method according to one of claims 1 to 7, characterized in that the methanol content of the polyvinyl alcohol after the thermoplastic molding 0 to 0.5 wt.% Is. Granules, foil, fibers, two- or three-dimensional Injection molded article or coating produced by thermoplastic molding of polyvinyl alcohol having a degree of hydrolysis of over 50 mole% and a viscosity of 0.1 to 30 mPas, characterized in that the thermoplastic molding at a temperature of 150 to 240 ° C in the absence of extrusion aids he follows. Use of a granulate, a foil, a two-part or three-dimensional injection molding or a Coating produced by thermoplastic molding of Polyvinyl alcohol with a degree of hydrolysis of more than 50 mol% and a viscosity of 0.1 to 30 mPas, wherein the thermoplastic Shaping at a temperature of 150 to 240 ° C in the absence of extrusion aids and the material thus obtained has a methanol content of 0 to 0.5 wt.%, in pharmaceutical or cosmetic applications.