RU2115670C1 - Composition for thermally molded articles being in contact with food products on the base of cellulose esters - Google Patents

Abstract

FIELD: production of cellulose esters which are used by production of packing materials having antimicrobial activity; production of extrusion and irrigated films, consumers packing and other articles being in contact with food products. SUBSTANCE: proposed composition comprises glycerine monobenzoate diacetate which is used as peptizing agent and as antimicrobial additive. Composition comprises, wt. p. : cellulose diacetate, 100; glycerine triacetate, 35; glycerine triacetate, 35; glycerine monobenzoate diacetate, 0.03-3.0; stabilizing agent, 0.3; ultramarine, 0.008. EFFECT: improved quality of product. 2 tbl

Description

 The invention relates to the production of plastics, in particular ether-cellulose plastics (etrols) used in the production of packaging materials with antimicrobial activity, including extrusion and irrigation films, roll materials, consumer packaging (injection molded, extrusion-blown) and other products, in contact with food (butterdishes, bread bins, etc.).

 In connection with the deteriorating environmental situation in the last decade, the problem of protecting food products from microbial contamination has arisen. One possible way to solve this problem is to create packaging materials with fungistatic and / or fungicidal properties. It is possible to impart the indicated properties to the polymer material by introducing special biocidal additives into the plastic composition.

 Known compositions for plastics based on cellulose esters (etrols) approved for contact with food by health authorities (ed. St. 1728260 class C 08 L 1/12; ed. St. 1659435 class C 08 L 1/12 1991; Packaging materials based on food etrols. Vol. 11, M., 1995, AgroNIITEIPP). These compositions contain plasticizers, dyes, and other processing aids. Etrols, having a certain set of properties: technological (wide range of plasticity), operational (stability in fats, sour-milk and other media, high sanitary-chemical goodness), are used for processing by advanced methods of thermoforming into films, roll materials, consumer containers of various sizes. However, none of the known etrols has such a property as antimicrobial activity.

 In recent years, scientific publications have appeared on the creation of so-called “active” shells containing various additives in the polymer matrix that give the material antioxidant, antimicrobial activity and other useful properties (V. Bugorkova and others. Main directions for creating photo- and biodegradable polymer materials (review). - Plastics, N 9, 1991, S. 48-51).

 The introduction of additives with antimicrobial activity into the polymer matrix contributes to the production of packaging materials and consumer packaging, eliminating the introduction of preservatives into a packaged food product with a high degree of contamination.

 The closest in technical essence and the achieved result to the invention is a composition based on cellulose ester (diacetate, cellulose acetate propionate), plasticized with a mixture of triacetin (TA) and dicarboxylic acids based oligoesters of various chemical nature.

 The composition contains, in parts by weight: cellulose ester diacetate (DAC) or cellulose acetate-propionate (APC) in an amount of 100; plasticizer 15 - 35; Ca stearate 0.3; ultramarine 0.008. For the matting of etrols, titanium dioxide in an amount of 3 parts by weight is introduced into the composition. As a plasticizer, a mixture of triacetate with dibutyl ether of polyethylene glycol adipate sebacinate or polyethylene glycol adipate (PPA-4) in the ratio of 2.5 to 350 is used.

 However, products from such compositions do not possess antimicrobial activity.

 The objective of the invention is the creation of a thermoformable composition based on plasticized cellulose ester (DAC), the products of which possess antimicrobial activity against pathogenic microflora.

со следующими показателями качества: эфирное число 660-750 мгКОН/г кислотное число 0,6-4,0.This is achieved by introducing into the composition of the composition of small amounts of antimicrobial additives approved for contact with food products. The choice of biocide (biostabilizer) and the optimal ratios of polymer (DAC), plasticizer is determined by the following: according to the invention, glycerol monobenzoate diacetate is used as an antimicrobial additive in such quantities as to provide the necessary concentration on the surface of the packaged product, which is most susceptible to microbial desaturation. The immobilization of the additive on the polymer matrix ensures the prolongation of its action, the possibility of reducing the amount of preservative introduced directly into the food product, or the absence of the latter in the product by ensuring its maximum concentration on the outer surface of the product most susceptible to microbial contamination. As a multifunctional organic additive, which simultaneously functions as a plasticizer, structure-forming agent and biocide, (MBDG) is used - benzoic acid ester - glycerol monobenzoate diacetate

with the following quality indicators: ether number 660-750 mgKOH / g acid number 0.6-4.0.

 The use of benzoic acid esters having a pharmacological effect is widely known in the technology for producing drugs. The latter are involved in the respiratory cycle of microorganisms. Therefore, it can be predicted that they will be good biocides. Indeed, MBDG has antimicrobial activity in relation to text cultures of microscopic fungi of the corresponding species, aerobic mesophilic bacteria.

 Using modern instrumental methods (rheological, physicomechanical, small-angle scattering of polarized light by a helium-neon laser, electron microscopy), it was established that MBDH plays the role of not only a biocide in plastic compositions, but also a plasticizer and nucleating agent. Depending on its concentration, which according to the invention varies from 0.3 to 3.0 parts by weight per 100 parts by weight of polymer, the resulting granules (ethrols) can have a given set of technological and operational properties. So when using a TA - MBDG mixture (up to 2 wt.%) As a plasticizer, film samples obtained from the thermotropic melt of the etrol composition have a "ribbon" structure, which is one of the morphological structures characteristic of the liquid crystal state of the polymer matrix. Change in the structure of the polymer (cellulose diacetate) during processing, i.e. the transition from amorphous to mesophase is accompanied by a deterioration in technological parameters, namely, it leads to a sharp increase in the melt viscosity. At the same time, products (film, packaging) obtained from a polymer with realized mesophase are economically viable, because with a smaller thickness, more durable products with high performance are obtained. When MBDG is used as the main plasticizer during the processing of ethanol compositions and films by extrusion, there is no transition of DAC to a liquid crystalline state.

 The introduction of small additives MBDG in the composition of the plasticizer does not reduce the inherent in this class of materials high stability in lipids, significantly increases the water resistance.

 Thus, materials obtained from modified MBDH ethanol compositions have better rheological indicators (melt viscosity and processing temperature decrease, shear rate and shear stress move to the region of lower values), higher strength and deformation properties, sanitary-chemical indicators, and water resistance. The material has a new property - bacteriostatic and fungistatic resistance.

 The invention is carried out as follows.

Example 1. 100 wt. including cellulose diacetate with a content of bound acetic acid of 56.4% are mixed in a high-speed turbo mixer with 0.3 wt. including calcium stearate and 0.008 wt. including ultramarine (mixing time of the dry components 8 min) at a temperature of up to 70 ^o C with 35 wt. including plasticizer triacetin, at the same time injected 0.3 wt. including glycerol monobenzoate diacetate (mixing time 12 min).

The resulting mixture is homogenized in an extruder at a melt temperature at the outlet of the extruder head of 160 ^o C. The obtained bundles are cooled and cut into granules, from which samples for testing in the form of a tape 10-15 cm wide, 0.04 cm thick are formed on a slit head. The temperature of the molding tape in the zones of the extruder: 1 - 180 ^o C, 2 - 150 ^o C.

 Example 2. It is carried out according to example 1, while the amount of modifier 3 wt. h

 The compositions of the examples and their properties are given in table. 1. The stabilizer (calcium stearate), dye (ultramarine) are the target functional additives and are used in the proposed composition in traditional proportions, in the examples their optimal amounts are given. As starting components according to the invention, cellulose diacetate for ethrol is used; glycerol triacetate (triacetin); glycerol monobenzoate diacetate; calcium stearate; ultramarine.

 In the table. 2 shows methods for determining properties that provide the purpose of the invention.

As can be seen from the above data, the modified MBDG ethanol compositions have an effective viscosity, a decimal order lower than that of the prototype. At the same time, the processing temperature decreases by 30 ^o C and the level of migration of low molecular weight substances into the product decreases.

 Products from ethrol modified with MBDG have high antimicrobial activity (fungicidal and fungistatic properties) in relation to pathogenic microflora, molds, and yeast.

Thus, the use of the proposed compositions based on cellulose diacetate used in the manufacture of packaging materials with antimicrobial activity compared to the traditional food grade ethrol (prototype) provides the following advantages:
the energy intensity of the process is reduced due to a sharp decrease in the viscosity of the processed composition and the temperature of processing the melt into products;
plastics with antimicrobial activity are obtained, the products of which can be used in contact with products subject to a high degree of contamination.

Claims (1)

Composition for thermoformed articles in contact with food, based on cellulose esters, containing cellulose diacetate, a plasticizer - glycerol triacetate, processing aids: calcium stearate and ultramarine, characterized in that the composition additionally contains glycerol monobenzoate diacetate of the general formula as a plasticizer and antimicrobial additive

in the following ratio of components, parts by weight:
Cellulose Diacetate - 100
Glycerol Triacetate - 35
Glycerol monobenzoate diacetate - 0.3 - 3.0
Calcium Stearate - 0.3
Ultramarine - 0.008

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