RU2537009C2 - Biodegradable thermoplastic composition based on cellulose diacetate - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to a biodegradable thermoplastic composition, applied in the production of films and various thermally moulded products in the form of consumer containers. The composition contains cellulose diacetate, filler, represented by the bone tissue, a non-ionogenic surface-active substance - syntanol and a cationic surface-active substance - quaternary ammonium compounds as technological additives.

EFFECT: obtained composition possesses good rheological characteristics and biodegrades under an impact of light, moisture, soil microflora.

2 cl, 2 tbl

Description

The present invention relates to the production of thermoplastic compositions based on plasticized cellulose diacetate used for processing into various thermoformed containers, including for contact with food products.

The objective of the invention is the creation of environmentally friendly ether-cellulose plastics (cellulose diacetate) with different service life, namely with sufficient operational stability under various operating conditions, during natural aging, and easily degradable (biodegradable) when disposing of obsolete products.

The use of biodegradable polymer materials for the production of consumer goods should be the main direction of reducing the quality of solid waste, as it will ensure their rapid decomposition under the influence of heat, moisture, light and microorganisms.

In Russia, the industrial development of biodegradable polymer materials based on plant materials is at the initial stage, while in Western Europe and the USA the creation of such materials has been widely used.

In Italy, Novamont launches Nator-Bi biodegradable material. It includes polyamide mixed with oxidizing hydrophilic compounds having a low molecular weight. Under the influence of environmental microorganisms, the material decomposes into monomers and complete destruction occurs within a few months. The material is easily processed on equipment and is used for the manufacture of disposable tableware, medical devices, and surgical instruments (containers and packaging, containers. Express information. VINITI, M., 1991, No. 45, p. 8. Packaging materials subjected to biodegradation).

The company Wamer-Zamrert (USA) produces material based on amide compounds. It is used for making boxes, for packing eggs, diapers, wrapping films, and cosmetic accessories. (Container and packaging, containers. Express information. VINITI, M., 1992, No. 43, p.5-9. Packaging materials subjected to biodegradation).

In Switzerland, Flunteraplast based on amide compounds with the addition of polyethylene (20-50%) has been developed. This material undergoes incomplete decomposition, has an increased sensitivity to moisture. It decomposes by 90% within 42 days (Container and packaging, containers. Express information. VINITI, M., 1992, No. 47, pp. 5-9. Packaging materials that are biodegradable).

Tubize Plastics (France) released 2 materials:

- Biopac, which is made from substances of plant origin, based on cellulose acetates with plasticizers - additives that accelerate decomposition. 50% decomposition occurs within 6-12 months. Used for packaging household appliances;

- Biocell 163 based on cellulose acetate. After immersion in water, the material begins to absorb it and after 6 months. 40% of the material decomposes, turning into carbon dioxide and water. Complete destruction takes place within 18 months (Container and packaging, containers. Express information. VINITI, M., 1992, No. 4, pp. 6-8. New biodegradable polymer materials for packaging purposes).

There is a new material on the market, released by Union Carbide (USA), based on caprolactam under the trade name Tone. It combines well with other thermoplastics. Biodestruction is observed within 6 months. (Container and packaging, containers. Express information. VINITI, M., 1992, No. 43, p.5-9. Packaging materials subjected to biodegradation).

Citibag inq. (USA) produces biodegradable polymer bags for collecting urban waste; the polymer film for the manufacture of such bags is obtained on the basis of low density polyethylene and polycaprolactone (5-20%) with the addition of a suitable biodegradation catalyst. The advantage is the ability to dig household garbage into compost pits directly in bags.

Serial production of self-degradable polymer films is carried out by the company of the USA, Canada under the trade names Polyclean, Ecostar, Ampacet. The basis for these films is low density polyethylene. (Container and packaging, containers. Express information. VINITI, M., 1992 No. 9, No. 15, 1991 No. 33. Biodegradable packaging materials).

However, in all known cases, polyolefins are used as the polymer base. In addition, polymers with a controlled service life contain special additives that provide photodegradability, which are toxic and can pollute the environment.

The proposed biologically degradable thermoplastic composition based on cellulose diacetate is deprived of these disadvantages, because all components used in the composition are biologically inert.

The closest in technical essence and the achieved result to the present invention is a biodegradable thermoplastic composition based on cellulose esters (patent No. 2174132, Cl, C08L 1/12, 3/02, C08K 5/00, publ. 23.06.2000,) .

The composition in its composition contains in mass parts:

cellulose diacetate 30 parts by weight plasticizer - triacetin 30 parts by weight filler - starch 10 ... 50 parts by weight filler - hydrolysis lignin 10 ... 20 parts by weight

The purpose of the invention is the creation of a thermoformable composition based on plasticized cellulose diacetate, products from which are biologically destroyed by natural factors. This is achieved by the fact that the composition includes cellulose diacetate 29.8-59.8 wt.% (With the content of acetate groups 56.4%), a plasticizer triacetin and additionally contains bone tissue as an active filler.

Compared with the prototype, the proposed thermoplastic composition uses an active filler - bone tissue, as a material that is eaten by soil microorganisms and contributes to the mechanical destruction of the product due to loosening of the polymer structure. This quality leads to better penetration of water molecules (swelling) and microorganisms in the structure of the material obtained from the proposed composition. The amount of bone tissue introduced has an effect on the swelling rate of the material. Thus, the developed material has an adjustable service life, which allows us to predict the biodegradation period and choose its application.

The choice of the optimal ratios of the polymer (cellulose diacetate), plasticizer (triacetin), filler (bone tissue) and technological additives is due to the following.

According to the invention, bone tissue (native ground, meat, bone, fish, bone meal 10.0-40.0 wt.%) Is used as an organic filler that optimizes the biological destruction process of final products made from filled cellulose diacetate-triacetin compositions. ), however, preference is given to bones with a native hammer.

In this case, from filled compositions, products are obtained that are quite biologically destructible under the action of light, moisture, and soil microflora. The polymer binder, which is a highly concentrated solution of cellulose diacetate in triacetin, plays the role of a dispersion medium.

The bone meal used for filling has the following physical characteristics: in appearance, the flour should be free-flowing, without dense lumps or granules with a diameter of not more than 12.7 mm, a length of not more than two diameters and crumbling not more than 15%.

Feed (meat and bone, fish) flour is a non-food raw material obtained during the processing of cattle at the enterprises of the meat industry. Feed flour is intended for the production of dry animal feed.

At the enterprises of the meat industry, high-protein feed is produced from production wastes: meat and bone, bone, and flour from hydrolyzed feathers.

Grinding and sifting of fodder flour is carried out in installations for grinding (crushing), providing a powdered dry product without dense lumps that do not crumble when pressed. Particles must pass through a sieve with holes with a diameter of 3 mm. The content of particles with a diameter of up to 5 mm should be no more than 5%. The quality of animal feed meal must meet the requirements of GOST 17536-82.

The grinding size (for loose flour) in accordance with the state standard should be such that after sifting through a sieve with holes with a diameter of 3 mm, the residue on the sieve (particle diameter up to 5 mm) does not exceed 5%. The produced fodder flour should have a specific, but not putrid and not musty smell.

Bone tissue (native ground bone) is a special form of connective tissue with calcified intercellular substance. It is a living tissue in which there is a constant internal destruction and updating of biochemical structural components.

The intercellular substance of bone tissue consists of collagen fibers, inorganic salts and a binder. Collagen fibers comprise (by weight) 84 to 96% of the total organic matter content. The rest is a binder (cementitious) substance, which mainly consists of mucopolysaccharides. Water bound in bone tissue is combined with organic fillers. Inorganic substances of bone are mainly different calcium salts. So, fresh bone tissue contains 60% Ca ₃ (PO ₄ ) ₂ ; 5.9% CaCO ₃ and 1.4% Mg (PO ₄ ) ₂

The grinding of the native bone was carried out on the installation, the cutting tool of which is a worm cutter (patent for utility model No. 111462 dated 12/31/2010). After grinding in this installation, bone powder has a particle size of 80-250 microns. This fraction is then crushed by ultrasound (100 W) for 5 minutes and reaches a size of 8-20 microns.

The surfactant was selected according to the principle of the need to create a heterogeneous system with specified values of its effective viscosity in the selected processing temperature range. The surfactant was selected from cationic surfactants (CAS) - these are quaternary ammonium compounds of the type of halides, the number of aggregations is 169; micellar mass - 62000; KKM, mM - 0.92. This surfactant was used in the composition to improve the compatibility of the ingredients and achieve a high degree of homogenization.

The surface-active substance (nonionic surfactant) is syntanol (ALM-2), the general formula is: RO (CH ₂ CH ₂ O) _n H, where n = 2, R is an alkyl residue containing mainly (12 ... 14) carbon atoms. The number of aggregations is 140, the micellar mass is 90,000, CMC, mM is 0.24. This nonionic surfactant was used in the composition as an initiator of biodegradation.

The chemical properties of the surface of the filler, as a rule, determine the processes that occur at the "polymer-filler" interface. The selected filler and polymer have surface active centers capable of forming hydrogen bonds. The adhesive interaction at the polymer-filler interface is the adsorption interaction of two bodies, i.e. adsorption of the polymer binder on the surface of the dispersion phase of the filler. According to the invention, the ratio of components in the system is optimal, because with this ratio of components, a melt with a given effective viscosity is obtained, which ensures good wetting of the filler surface at a temperature higher than the melting temperature of the composition.

The selected ratio of plasticizer and cellulose diacetate in the polymer binder guarantees optimal conditions for the processes of wetting, adsorption and adhesion in the polymer-filler system, which provides better conditions for the physical and chemical (at elevated temperatures) interaction of the components of the composition.

From such compositions it is possible to produce consumer goods (disposable and reusable containers, various animal feeders, boxes, boxes, etc.).

The invention is implemented as follows.

Example 1. 29.8 wt.% Cellulose diacetate, 0.1 wt.% Nonionic surfactant, 0.1 wt.% Cationic surfactant, 40 wt.% Native bones are mixed in a high-speed turbo mixer for 15 minutes, then 30 are sprayed wt.% plasticizer (triacetin) and stirred for another 10 minutes

The resulting mixture enters the extruder for homogenization and melt production. The melt temperature at the outlet of the extruder head = 160 ° C. The obtained bundles are cooled by a stream of cold air and cut into granules with a diameter of 3-5 mm.

Samples for testing are formed from granules on an extruder with an alkaline head in the idea of a tape of 10-15 cm and a thickness of 0.04 mm. The temperature of the molding tape in the zones of the extruder: 130-140-150-155 ° C.

Example 2. Preparation of the composition according to example 1. As the polymer binder, cellulose diacetate is used in an amount of 59.8 wt.%, The filler is native ground bone, 10 wt.%.

Example 3. Preparation of the composition according to example 1. The polymer binder is cellulose diacetate, 34.9 wt.%, The filler is native ground bone, 34.9 wt.%.

Example 4. Preparation of the composition according to example 1. The polymer binder is cellulose diacetate, 29.8 wt.%, The filler is meat and bone meal, 40.0 wt.%.

Example 5. Preparation of the composition according to example 1. The polymer binder is cellulose diacetate, 59.8 wt.%, The filler is meat and bone meal, 10.0 wt.%.

Example 6. Preparation of the composition according to example 1. The polymer binder is cellulose diacetate, 29.8 wt.%, Filler - fish meal, 40.0 wt.%.

Example 7. Preparation of the composition according to example 1. The polymer binder is cellulose diacetate, 59.8 wt.%, The filler is fish meal, 10.0 wt.%.

The composition containing less than 10 wt.% Filler (bone) does not allow to obtain a material with a high degree of biodegradation. A mixed composition containing more than 40 wt.% Bone is not high-tech, the products are brittle, the plasticizer sweats to the surface of the product.

The compositions of the compositions according to examples and their properties are shown in table 1. As starting components, according to the invention, cellulose diacetate for ethrol, triacetin, bone tissue, nonionic and cationic surfactants are used.

Table 2 shows the methods for determining the properties that ensure the purpose of the invention.

Table 1 Example No. The composition, wt.% Technological and operational properties of materials Polymer DAC Plasticortortiacetin Filler Technol. additives Test temperature ° C Melt flow rate, g / 10 min at 190 ° C Physico-mechanical properties of the material Mushroom resistance of the material, score Microbiological resistance starch lignin Bone Cationic surfactant Nonionic surfactant σ _p , MPa ε,% Native bone Meat and bone meal fish flour Original After exposure to vermicompost Original After exposure to vermicompost one 2 3 four 5 6 7 8 9 10 eleven 12 13 fourteen fifteen 16 17 eighteen Prototype thirty thirty thirty twenty - - - 140 23 35.0 Test failed 10.0 Test failed - - Example 1 29.8 30,0 - - 40,0 - - 0.1 0.1 160 7 10.0 8.0 2.0 1,0 four Seediness of the surface 1 × 50 units. Example 2 59.8 30,0 - - 10.0 - - 0.1 0.1 160 13 15.0 10.0 3,5 1,5 3.0 Seediness of the surface 1 × 30 units. Example 3 34.9 30,0 - - 34.9 - - 0.1 0.1 160 9 15.0 Test failed 3.0 Test failed 4.0 Seediness of the surface 1 × 40 units. Example 4 29.8 thirty - - - 40,0 - 0.1 0.1 150 5 10.0 3.0 2.0 1,0 4,5 Seediness of the surface 1 × 50 units. Example 5 59.8 thirty - - - 10.0 - 0.1 0.1 150 19 12.0 7.0 3.0 1,5 4,5 Also Example 6 29.8 thirty - - - - 40,0 0.1 0.1 150 5 8.0 Test failed 2.0 Test failed 4.0 Also Example 7 59.8 thirty - - - - 10.0 0.1 0.1 150 twenty 8.0 3.0 3.0 1,5 4,5 Also

table 2 No. The name of indicators Test method one. Processing temperature of the composition, ° C GOST 11645-73 2. The melt flow rate of the composition (MFR) at a temperature of 190 ° C and a load of 2.16 kg, g / 10 min GOST 11645-73 3. Determination of physical and mechanical properties (elongation,%; tensile strength, N / m ² ) GOST 14236-81 four. Microbiological resistance GOST 9.053-75 GOST 9.049-91 5. Mushroom resistance of the material, score GOST 9.048-89 6. Determination of resistance to chemical media GOST 12020-72

Claims (2)

1. Biologically degradable thermoplastic composition, which contains cellulose diacetate 29.8-59.8 wt.%, Plasticizer - triacetin 30 wt.%, As technological additives nonionic surfactant - syntanol 0.1 wt.%, Cationic surfactant -active substance - Quaternary ammonium compounds 0.1 wt.%, biodegradable filler - bone tissue 10.0-40.0 wt.%. 2. The composition according to claim 1, characterized in that as the bone tissue using native bone ground, meat and bone or fish meal.