DE19802718A1 - Biodegradable thermoplastic polymer blends, useful for the production of films, injection moldings, e.g. bottles, disposable trays and dishes etc. - Google Patents

Abstract

Compostable (biodegradable) thermoplastic polymer compositions (I), obtained by a compounding/extrusion process involving homogeneous mixing of a melt containing flour (biopolymer), plasticizers and other biodegradable thermoplastic polymer components. Independent claims are also included for the following: (a) a process for the production of biodegradable polymer blends (I) which involves using water as a plasticizer in an endothermic mixing/compounding process; and (b) a process for the production of biodegrading polymer blends (I) by mixing/compounding in the absence of water using an exothermic extrusion process.

Description

The present invention relates to compostable, thermoplastic polymer blends and compositions, the renewable raw materials and thermo plastic degradable polymers based on synthetic or natural Raw materials are manufactured included. The thermo according to the invention Plastic polymer blends can be made using the usual methods of plastics processing industry for example foils, bottles, trays, Food trays for selling fast food products, sales or Process frozen packaging and injection molded products. This biological degradable objects have usage properties analogous to that conventional plastic materials, but are biodegradable or compostable according to the proposed standard DIN 54 900 or OK Compost Certificate or ASTM D 5338. The invention also relates to a method for Production of such polymer blends and compositions and from Articles made of polymer blends and compositions.

Biodegradable polymer blends and articles made from them based on renewable raw materials such as starch and cellulose are known and are also commercially available. A number of patent applications in this area describe this:
Warner & Lambert: US 5,095,054; EP 118 240; EP 298920; EP 304 401; EP 326 517; EP 327 505; EP 404 723; EP 391 853;
Novamont: US 5,412,005; U.S. 5,286,770; U.S. 5,258,430; U.S. 5,234,977; WO 90-10671; WO 92-19680; WO 92-02363; WO 92-14782; EP 0 560244;
Griffin / Coloroll: EP 0 045 621;
Otey: US 3,949,145; US 4454 268; U.S. 4,337,181; U.S. 4,133,784;
Parke Davis: WO 92-16584; WO 94-16020; U.S. 5,393,804; WO 94-42567;
BIOTEC: WO 90-05161; US 5,314,934; US 5 280 055; DE 42 37 535; WO 96-31561; WO 96-19599.

All of the aforementioned patents and patent applications deal with the Starch raw material and polymer mixtures with starch and other degradable ones Polymer components. Regardless of whether in the aforementioned exemplary The starch components are printed by extrusion cooking with water and Plasticizers led to a destructurized starch intermediate or anhydrous using, for example, glycerin to form thermoplastic starch Intermediate product are implemented and thus film-forming properties obtained or used as a non-film-forming filler and further Process sequence compounded with the thermoplastic polymer components , the above-mentioned publications only refer to the Use of renewable raw materials based on starch such as native starches, modified starches or starch derivatives as raw materials. Gaining strength is made from cereals or tubers, preferably from corn, wheat, Potatoes or tapioca through the isolation of the starch in complex Separation and separation processes from an aqueous suspension and subsequent energy intensive drying as starch powder with grain size diameters of 10-100 mm, rarely from 5-200 mm with a natural water content of 13% for corn, wheat and tapioca starch and 18% for potato starch. Of the average starch content of the raw materials is very different and is for maize 60-70%, wheat 53-70%, tapioca 20-30% and potatoes 12-20%.

The object of the present invention is to provide a cheaper and available to use renewable agricultural raw material for the production of thermoplastic polymer mixtures is suitable. The new biological Degradable polymer blends are designed to meet the demands of plastics  manufacturing industry and to produce degradable Films, composite films, packaging materials, bottles, injection molded products and fibers for textile applications. In doing so, they should be compared to starch plastics at at least the same level of technical physi properties can be manufactured more cost-effectively and be more independent of raw materials.

These requirements are met with the features of the present invention, where, as a renewable raw material, coarse to finely chopped grain z. B. from Corn, wheat, rye, barley or tubers such as potatoes can be used. The crushed grain essentially consists of carbohydrates (55-75%, thereof approx. 90% starch and dextrins, sugars and pentosans), approx. 15% water, 10-12% proteins / protein / glue, cellulose from the fruit and Shell walls, oils and fats (2-5%), minerals and vitamins. At In terms of life cycle assessments, the flours have compared to the starch Advantages that the energy-intensive starch production, their secondary and Waste products and waste water are eliminated.

The grain as flour, semolina or grist is in its naturally occurring form initially not thermoplastic and therefore unsuitable for use as film-forming component in degradable thermoplastic polymer mixtures. Therefore, the flour is extruded under pressure and temperature disrupted using plasticizers such as water, polyvalent Alcohols, for example ethylene glycol, glycerin, mannitol, sorbitol and others Polyols or polyglycols or derivatives thereof. Can also be used as plasticizers Polyvinyl alcohol holes and derivatives thereof, low molecular weight polyesters, polyesters amides, polyester urethanes can be used. The plasticizers have that Purpose to reduce the decomposition temperature of the flour so that a Melt is formed which, with further degradable polymers, becomes one for the plastic processing industry ready-to-use thermoplastic in granulate form can be processed by the melt from the flour / plasticizer Mixture and the further polymer mixed homogeneously in the melt phase or that the melt is extruded as a tape through a flat die and the still plastic band directly through a forming process,  equate to a thermoforming and / or thermoforming process, to one Object is molded.

To the intermolecular coupling of the hydrophilic natural polymers, which as macromolecular carbohydrates are contained in the flour, and the hydrophobic, To promote degradable polymers, phase mediators are added. Known Phase mediators are, for example, ethylene vinyl alcohol, polyvinyl alcohol, Glycerol esters, polyvinyl pyrolidone and block copolymers with hydrophilic and hydrophobic groups.

The preferred embodiment is the preparation and formation of the phase mediator during the mixing process in the melt phase by the Melt is drained as completely as possible and the phase mediator Reaction product by transesterification of the polymeric carbohydrates with the other polymers are formed. Particularly suitable for this transesterification reaction are homopolymer and copolymeric polyesters, polyester amides and Polyester urethane.

The mixtures of flours with plasticizers, plasticizers and phase mediators that can be produced in this way have thermoplastic properties that enable further compounding with biodegradable, synthetic or natural polymers in order to meet the necessary physical and material requirements for an industrially usable plastic. In particular, the hydrophobic properties have to be improved by compounding with other biodegradable polymers. The thermoplastics listed below are suitable as further, biodegradable polymer components:

• - Aliphatic polyesters such as polycaprolactone, bionolle, polylactide, polymers of Polyhydroxybutyric acid and / or copolymers with valeric acid
• - Polyester copolymers consisting of aromatic and aliphatic blocks
• - polyester amides
• - polyester urethanes
• - cellulose derivatives
• - and mixtures of these degradable thermoplastics.

The group of aliphatic polyesters includes, for example:

• - Polycaprolactone, trade name Tone Polymer
• - Bionolle, polycondensation product made from succinic anhydride or Adipic acid anhydride and butanediol
• - Polylactide, biotechnologically produced from lactic acid.

Polyester copolymers from aliphatic and aromatic blocks, e.g. B. from aliphatic diols, aliphatic and aromatic dicarboxylic acids (US 5 446 079, WO 91/18036, WO 92/13019, WO 92/13020, WO 92/09654, WO 95/14741, EP 552 896, WO 96/07687, WO 96 / 15173-6).

Polyester amides are described in EP 0 641 817.

Polyester urethanes are e.g. B. described in EP 539 975 and in WO 89/05830 Polyol prepolymer and polyisocyanates.

Cellulose derivatives are available as thermoplastics e.g. B. as cellulose acetates (CA), Cellulose acetate butyrate (CAB), cellulose acetate propionate (CAP) being the Degree of substitution is 2.5 and below, on the one hand thermoplastic Properties and on the other hand to maintain biodegradability.

Other additives such as dyes, plasticizers, waxes, flame retardants, Stabilizers, organic and inorganic fillers and fibers are used depending on Requirement profile of the polymer blend added.

The invention is described below with reference to and in the Drawing illustrated embodiment explained in more detail:

Example: Production of everyday objects

The polymer blends according to the invention are preferred by compounding of the components mentioned in a twin-screw extruder. Of the preferred extruder is a co-rotating, tightly intermeshing twin screw  kneader with tightly interlocking screw profile and with a process length of 32-56 length / diameter with a screw diameter of for example D = 40 mm, a screw speed of 30-300 rpm, one Throughput of 45-100 kg / h. The extruder has the option of entering or leaving multi-stage degassing and is individually heatable with eight (or up to twelve) Kneading zones and at the end of the extruder with a nozzle plate with four 3 mm nozzles Diameter or alternatively with a flat nozzle if the hot, thermoplastic melt immediately after leaving the extruder an object is to be reshaped.

Example: Production of granules for further processing

In the first zone of the extruder, the feed zone, the raw materials (flour, Plasticizers / plasticizers, possibly phase mediators, degradable thermo plastic hydrophobic polymer) metered. The raw materials can over corresponding metering devices are added continuously or individually as a homogeneous premix. In the second zone of the extruder there is a slow start Pressure of 1 bar or higher built up at a housing temperature of at least 140 ° C. Plasticization begins in the third zone of the extruder at a housing temperature of 180 ° C and 1 bar pressure or higher, which in the fourth zone of the extruder is continued under the same conditions. In the The fifth zone of the extruder is used for further plasticizing and compoun dation, the water still contained in the mixture by degassing is removed as completely as possible. In the sixth and seventh zones of the The mixture is extruded further at an increased pressure of 1 bar or higher homogenized, the temperature rising up to 220 ° C. In the eighth and the last zone, the hot melt is ejected, possibly remaining water evaporates.

The extruded strands are cooled in a water bath, strand pelletized and packaged. The process conditions will vary depending on Use of the hydrophobic degradable blend components varies, the Melt temperature is between 120 ° C and 220 ° C.  

Possible uses of the polymer materials according to the invention are, for example:

• 1. New applications for agricultural raw materials such as flour from z. B. corn or wheat for the production of biological plastics and goods made from them.
• 2. Process for the production of biodegradable articles of daily use from renewable raw materials.
• 3. Polymer mixtures from renewable raw materials with thermoplastic Properties for use in the plastics processing industry.

example 1

In the previously described, a raw material mixture is produced at a maximum melt temperature of 205 ° C. and at a pressure of 6 bar

• - 35 parts of corn flour
• - 13 parts glycerin
• - 15 parts of polyvinyl alcohol
• - 47 parts of polycaprolactone

compounded.

The thermoplastic granulate obtained has an MFI (g / 10 ') of 6 and is suitable for the production of blown films.

Example 2 Twin-screw extruder as in Example 1

Process conditions: maximum melt temperature 220 ° C, maximum pressure 6.5 bar

Raw material composition

• - 41 parts of corn flour
• - 18 parts glycerin
• - 41 parts PLA, Lacea H 100, manufacturer Mitsui Toatsu

The granules obtained have an MFI (g / 10 ') of 8 and are suitable for Production of blown and flat films.  

Example 3 Twin-screw extruder as in Example 1

Process conditions: max. Melt temperature 190 ° C, max. Pressure 2.5 bar

Raw material composition

• - 35 parts of corn flour
• - 12 parts glycerin
• - 63 parts of polyester amide BAK 1095, manufacturer Bayer AG

The granules obtained have an MFI (g / 10 ') of 15 and are suitable for Production of blown films and filaments.

Example 4 Twin-screw extruder as in Example 1

Process conditions: max. Melt temperature 190 ° C, max. Pressure 2.5 bar

Raw material composition

• - 33 parts of corn flour
• - 14 parts of a mixture of glycerol / sorbitol 1: 1.2
• - 63 parts of polyester from aliphatic diols and aliphatic-aromatic Dicarboxylic acids.

The granules obtained have an MFI (g / 10 ') of 15 and are suitable for Production of blown films and filaments.

Example 5 Twin-screw extruder as in Example 1

Process conditions: max. Melt temperature 210 ° C, max. Pressure 7.5 bar

Raw material composition

• - 35 parts of corn flour
• - 15 parts of a mixture of glycerol / sorbitol 1: 1.2
• - 50 parts of gellulose diacetate DS 2.0

The granules obtained have an MFI (g / 10 ') of 10 and are suitable for Manufacture of flat foils and injection molded articles.  

Example 6

A melt from the raw material composition from Example 5 is replaced by a Flat die extruded. The extruded 20 cm wide tape was immediately after leaving the extruder by a pressing device consisting of a Stamp and a shape pressed into the format of a bowl with the following Dimensions: length 23 cm, width 14.5 cm, depth 2.5 cm. This tray is as compostable disposable packaging for the snack and fast food sector usable. Also as packaging for e.g. B. fruits, vegetables and meat.

Example 7 Raw material composition

72 g corn flour
6 g hard wax - carnauba wax
12 g PVOH - Mowiol 56/98
10 g water.

The raw material mass is in the extruder under the conditions of the cooking extrusion brought a melt. The melt is fed through a slit nozzle as a band extruded, the melt by spontaneous evaporation of the water foams. This still plastic foam immediately becomes objects reshaped. Containers, plates, trays, cups and are preferred Preserved serving trays for use as compostable disposable material.

Example 8

Composition and process conditions as Example 7, but that Extruded tape before forming with a waterproof paper is coated. The manufactured item is through the paper coating Moisture and grease repellent as well as increased heat resistance. The manufactured one The item is completely biodegradable, so no disposal there are problems. Furthermore, the article produced is hygienic perfect. The paper coating increases the dimensional stability of the manufactured Subject.  

Example 9 Raw material composition

100 parts of corn flour
25 parts of Degranil (40% dispersion of a PU preparation).

The raw material mass is in the extruder under the conditions of the cooking extrusion brought a melt. The melt is fed through a slit nozzle as a band extruded, the melt by spontaneous evaporation of the water foams. This still plastic foam immediately becomes objects reshaped. Containers, plates, trays, cups and are preferred Preserved serving trays for use as compostable disposable material. The items are elastic, waterproof, food approved and compostable.

The single figure shows a schematic longitudinal section of a Device for performing the method according to the invention and for Production of commodities according to the invention.

The device designated overall by 10 has an extruder 12 with a feed hopper 14 and a screw 16 , as is known per se for the injection molding of plastic. The extruder 12 is provided with heaters 18 . It has a slot nozzle 20 . Furthermore, the extruder 12 has devices for degassing which are known per se and are not shown because of the simple illustration.

A feedstock composition, such as is specified above as example 6 or 7, is filled into the extruder 12 through the filling hopper 14 . By rotating the screw 16 with a drive device, not shown, the raw material composition is mixed to a homogeneous mass, compacted and plasticized and heated to an adjustable melt temperature by the heater 18 . In addition, degassing of the raw material mass in the extruder 12 is provided in a manner known per se. The raw material mass is extruded into a flat and wide band 22 through a slot nozzle 20 . The extruded band 22 is plastically deformable after leaving the extruder 12 .

The strip 22 consisting of the extruded raw material mass passes after exiting the slot nozzle 20 between a pair of rollers 24 of a smoothing mill 26 . In the smoothing mill 26 , a paper strip 28 of the width of the extruded strip 22 is applied to the extruded strip 22 . The paper tape 28 is coated with biodegradable polymers, as is known per se, and is therefore waterproof. The paper tape 28 is unwound from a supply roll 30 and drawn together with the extruded tape 22 between the rollers 24 of the smoothing mill 26 . Due to the pressure exerted by the rollers 24 , the paper band 28 is connected to the extruded, still plastic band 22 . The connection can be made by material closure without additives. In the illustrated embodiment, a preferably biodegradable, food-grade, health-safe adhesive is applied with an adhesive nozzle 29 between the paper band 28 and the extruded band 22 before the paper band 28 is rolled onto the extruded band 22 with the rollers 24 of the smoothing roller 26 .

After the smoothing mill 26 , the strip 22 passes between a pair of form rolls 32 of a form rolling mill 34 . Circumferential surfaces of the shaping rollers 32 are provided with elevations 36 and recesses 38 which correspond to the shape of the objects to be produced from the raw material mass, ie the elevations 36 and recesses 38 form positive and negative forms of the utility objects to be produced. In the exemplary embodiment shown, the consumer items produced are 40 serving trays for the sale of fast food. The elevations 36 and recesses 38 of the form rollers 32 work together, they form the extruded band 22 , which is also plastic in the form rolling mill 34 , together with the paper band 28 , with which the extruded band 22 is coated, into the commodities 40 . The shaping can also be carried out, for example, by deep drawing, as is known from plastics processing (not shown).

It should be added that the strip 22 arrives immediately after exiting the extruder 12 into an air-conditioning space, which it only leaves again after it has been shaped, that is to say after exiting the form-rolling mill 34 . The air-conditioning space encloses at least the smooth rolling mill 26 and the form rolling mill 34 . The air conditioning room is not shown in the figure because of the clear representation. In the air-conditioning room, the band 22 is conditioned in a manner known per se, that is to say it is kept at least at a temperature which prevents premature curing and enables the plastic shaping. In order to prevent the strip 22 from cooling prematurely, the rollers 24 of the smoothing roller 26 and the shaping rollers 32 of the shaping roller 34 are heated. The conditioning can also be carried out, for example, by applying steam to the belt 22 under pressure in the air conditioning room.

With a form of the rolling mill 34 followed by a separating device 42 is the formed belt 22, 28 separated by two perpendicular to the belt 22 against each other movable blades 44 in the portion shells 40th The extruded tape 22 with the molded paper tape 28 hardens into dimensionally stable portion trays 40 . Due to the coating with the waterproof paper tape 28 , moist, greasy or hot goods can be inserted into the portion trays 40 without problems, without the portion trays 40 softening. The portion trays 40, including the paper tape 28 with which they are coated, are completely biodegradable, suitable for food and harmless to health. For disposal, the paper tape 28 can also be pulled off the portion tray 40 . In addition, it is pointed out that the portion trays 40 can also be produced without paper coating.

Claims (24)

1. Thermoplastic, compostable polymer composition obtained by Compounding extrusion by homogeneously mixing a melt of flour (Biopolymer), plasticizers and other degradable thermoplastic Polymer components. 2. Compostable polymer composition according to claim 1, characterized in that the further, degradable thermoplastic polymer components are selected from the following group:

• - aliphatic polyester
• - aromatic polyester
• - Polyester copolymers with aliphatic and aromatic blocks
• - polyester amides
• - polyester urethanes
• - cellulose derivatives
• - Starch-based polymer blends
• - Cellulose-based polymer blends
• - polyvinyl alcohol
• - Derivatives and / or blends of the aforementioned components.

3. Compostable polymer composition according to claim 2, characterized characterized in that as a biopolymer flour made by crushing Grain or tuber products is used.   4. Compostable polymer composition according to one of claims 1 to 3, characterized in that as biopolymeric agricultural raw material maize, wheat, Triticale, rye, barley, oats, sorghum, millet, potatoes, cassava, tapioca or maranta in crushed form is used as semolina, flour or meal. 5. Compostable polymer composition according to one of claims 1 to 4, characterized in that a plasticizer or plasticizer for the flour is contained like glycerin and / or glycerin derivatives, polyvalent Sugar alcohols such as sorbitol and / or derivatives of sugar alcohols, glycols and / or their derivatives, low molecular weight polyesters, polyester amides and / or Polyvinyl alcohol, lactic acid, polylactic acid or oligomers thereof, some of which the flour swell or dissolve and lower the decomposition temperature so that the flour melts. 6. Compostable polymer composition according to one of claims 1 to 5, characterized in that the plasticizer or mixture various plasticizers in an amount of 5-40 wt .-% based on the Flour is included. 7. Compostable polymer composition according to one of claims 1 to 6, characterized in that water is used as the plasticizer in the order of 0.1-30% by weight, being for thermoplastic Polymer blends as granules of water content before leaving the Extruder is reduced to 1% or less. 8. Compostable polymer composition according to one of claims 1 to 7, characterized in that water is used as the plasticizer in the order of 0.1-30% by weight, whereby for polymer mixtures, the after leaving the extruder as a foamed belt to further Commodities are processed, the water as a blowing agent in the The melt remains and only emerges in vapor form after the extrusion an equilibrium moisture content is established in the polymer mixture.   9. Thermoplastic, compostable polymer composition after Claim 1, characterized in that the further polymer components from aromatic and / or aliphatic dicarboxylic acids and other polyols are manufactured. 10. Thermoplastic, compostable polymer composition after Claim 1, characterized in that as a further polymer components contains aliphatic polyester and / or copolyester such as polycaprolactone, Polyhydroxybutyric acid, polylactic acid, polyhydroxybutyric acid-valeric acid- Copolymer. 11. Thermoplastic, compostable polymer composition according to one of the preceding claims, characterized in that a phase mediator is used which is obtainable as a block polymer by anhydrous mixing of biopolymers with reactive polymers of the group

• - polyester urethane
• - polyester amide
• - homopolymer polyester
• - copolymeric polyester.

12. Thermoplastic, compostable polymer composition according to one of the preceding claims, characterized in that as further Additives contain at least one of the following components: fillers, Anti-flame agents, preservatives, water repellents, dyes, Cellulose esters, cellulose fibers, polyvinyl alcohol, polyvinyl acetate, styrene butadiene Copolymers, fatty acid derivatives, fibers, crosslinking agents such as dicarboxylic acids and their anhydrides and / or sodium trimetaphosphate, resins based Urea formaldehyde, melamine formaldehyde, phenol formaldehyde, 13. Process for making a thermoplastic, compostable polymer Composition according to one of the preceding claims, characterized characterized in that the polymer blend using water as a Plasticizer is obtained in an endothermic mixing / compounding process.   14. Process for making a thermoplastic, compostable polymer Composition according to one of claims 1 to 12, characterized characterized in that the polymer blend by anhydrous Mixing / compounding is obtained in an exothermic extrusion process. 15. A method for producing a thermoplastic, compostable polymer mixture according to one of claims 1 to 12, characterized in that the flour is obtained in an extrusion process by homogeneous mixing in the melt using plasticizers and other degradable thermoplastic polymers of the following group:

• - polyester urethane
• - polyester amide
• - aliphatic polyester
• - aromatic polyester
• - copolymeric polyester
• - cellulose derivatives
• - Starch derivatives
• - Starch blends
  and / or mixtures thereof.

16. Process for the production of a thermoplastic, compostable Polymer mixture according to one of the preceding claims, characterized characterized in that the mixing of the melt in a twin-screw extruder at a temperature of 120-240 ° C. 17. Process for producing a thermoplastic, compostable Polymer mixture according to one of the preceding claims, characterized characterized in that after homogeneous mixing in an extruder Melt is drawn off through nozzles, the extrudate being cooled with water and then granulated.   18. Process for producing a thermoplastic, compostable Polymer mixture according to one of the preceding claims, characterized characterized in that after homogeneous mixing of the melt a flat die is extruded and continuously in the thermoplastic Condition is transformed into a commodity. 19. Process for the production of a thermoplastic, compostable Polymer mixture according to claim 17, characterized in that the Granules of the polymer mixture, for example, before further processing by injection molding, bottle or foil blowing with a plasticizer and / or is conditioned with water. 20. Use of a thermoplastic, compostable polymer mixture according to one of claims 1 to 12 for the production of single and Multilayer films. 21. Use of a thermoplastic, compostable polymer mixture according to one of claims 1 to 12 for the production of injection molded products. 22. Use of a thermoplastic, compostable polymer mixture according to one of claims 1 to 12 for the manufacture of bottles and containers using form bubbles. 23. Use of a thermoplastic, compostable polymer mixture according to one of claims 1 to 12 for the manufacture of articles of daily use such as disposable dishes, trays, cups, plates, portion bowls, fast food dishes through direct forming of the hot thermoplastic melt. 24. Use of a thermoplastic, compostable polymer mixture according to claim 23, characterized in that the commodities are coated with water-repellent paper.