EA038718B1 - Biodegradable dishware production method - Google Patents

Abstract

A method of biodegradable dishware production from a mixture of components, by molding said mixture in mold at heating and under pressure, wherein for mixture a powdered composition of grain extraction cake is used with a particle size from 0.2 to 3.00 mm in an amount of 95-98 wt.%, having moisture content of not more than 9%, and a ground biodegradable film in an amount of 2-5 wt.%, the latter consists of the following components, wt.%: potato starch - 4.2-5.0, sodium alginate - 0.1-0.8, glycerol - 5.0-20.0, distilled water - the rest; to obtain the film said components are thoroughly mixed, treated with ultrasound, heated in water bath to a temperature of 80-90°C, cooled to temperature of 50°C, the film is formed by irrigation on a glass surface and dried at a temperature of 20-25°C, then the obtained film is ground to a particle size of 0.01 to 3.20 mm; the powdered composition of grain cake and biodegradable film is leveled in a lower part of metal mold consisting of two parts by vibration during 0.2-0.5 min, then the mold is covered with its upper part, creating pressure by means of connection with a press 20-60 t, at a temperature of 120-160°C, then the mold is opened, pressure is reduced to atmospheric pressure and ready dishware is removed.

Description

The alleged invention relates to disposable tableware and packaging materials that are completely biodegradable without harming the environment and the method of its production. More specifically, the invention relates to disposable tableware that does not contain synthetic polymers that are resistant to corrosive environments, thus making the product biodegradable under environmental conditions during composting.

Known methods of producing composite biodegradable molded dishes from plant raw materials, which are used in industrial enterprises, imply the use of wheat straw, bran, compositions from harvest residues, composite mixtures from plant materials, which contain a synthetic polymer. Such methods make it possible to obtain articles of limited applicability, with low performance characteristics, low biodegradability due to the presence of synthetic components in the composition.

There is a known method of producing self-decomposing disposable tableware and a method for its production (patent for invention 2309652, Self-decomposing disposable tableware and a method for its production, IPC A47G 19/03, B65D 65/46, C08L 97/02, publ. 10.11.2007). This method of producing disposable tableware includes fine grinding and mixing of crop residues, corn flour, paper mulberry bark, moss, a mixture of flour from cereal grain at a specified mass% ratio of components. The mixture is molded into products of a given shape and size at a temperature of 140-150 ° C using a 500-ton hydraulic press.

The disadvantage of this method is the laboriousness of the technological process of manufacturing the product, the selection of raw components, the difficulty of maintaining the bonding capacity with the ratio of the components, minor deviations from the established requirements negatively affect the deformation-mechanical parameters, and the biodegradation period increases.

A known method of producing biodegradable molded products, in particular dishes and packaging (patent for invention EP 027907 B1, IPC D21J 1/00, D21J 3/00, publ. 09/29/2017). This method of obtaining biodegradable molded articles involves the use of water vapor pressure inside the composite mold for mixing bulk components with a granule size from 0.01 to 2.80 mm in an amount of 95-100 wt.%, Containing more than 14 wt.% Water. Placing the prepared mixture in a special mold, closing the mold and then simultaneously exposing the mixture to a temperature of 120 ° C or higher and a pressure of 1 to 10 MPa.

The disadvantage of this method is the difficulty of controlling the technological process, in particular, the intensity of the flow of water vapor and temperature, and the deviation of these parameters leads to rupture of the molded products.

The technical objective of the present invention is to develop a method for the production of a composite biodegradable molded tableware from a powder composition consisting of crushed grain meal and a biodegradable composite film having sufficient strength characteristics and biodegradability under specified conditions without harming the environment.

The technical problem is solved due to the fact that the method for the production of biodegradable tableware from a mixture of components, by molding said mixture in a mold under heating and under pressure, is characterized by the fact that according to the invention, a powdery composition of grain meal with a particle size of 0.2 up to 3.00 mm in an amount of (95-98) wt%, having a moisture content of not more than 9%, and a crushed biodegradable film in an amount of (2-5) wt%, the latter consists of the following components, wt%: potato starch - (4.2-5.0), sodium alginate - (0.1-0.8), glycerin (5.0-20.0), distilled water - the rest; to obtain a film, these components are thoroughly mixed, treated with ultrasound, heated in a water bath to a temperature of 80-90 ° C, cooled to a temperature of 50 ° C, the film is formed by pouring onto a glass surface and dried at a temperature of 20-25 ° C, then the resulting film is crushed to a particle size of 0.01 to 3.20 mm; a powdery composition of grain meal and biodegradable film is leveled in the lower part of a metal mold, consisting of two parts, by vibration for 0.2-0.5 minutes, then the mold is covered with its upper part, created by connection with a press pressure of 20-60 tons, at a temperature of 120-160 ° C, then the mold is opened slightly, the pressure is reduced to atmospheric and the finished dishes are removed.

The proposed method includes placing a predetermined amount of the specified initial powder composition (mixture) in the lower part, consisting of two parts, a metal mold for making dishes, leveling it using vibration for 0.2-0.5 minutes in the lower part of this press -forms. Then the lower part of the mold is covered with the upper one with the formation of a gap between the edges of the mold of 0.3-0.5 mm, heated to a temperature of 120-160 ° C and a pressure of 20-60 tons is applied using a hydraulic press, then the pressure is released. The mold is opened and the finished dishes are removed.

To obtain biodegradable tableware, a mixture is used, including powder compositions consisting of grain meal with a particle size of 0.2 to 3.00 mm in an amount of 95-98 wt%, a moisture content of not more than 9% and a crushed biodegradable composite film, in an amount not more than 2-5 wt.%, consisting of the components of the mixture, wt.%: potato starch - (4.2-5.0), sodium alginate - 1,038718 (0.1-0.8), glycerin - (5, 0-20.0), distilled water - the rest; followed by crushing the dried film to a particle size of 0.01 to 3.20 mm.

The use of the mixture in this percentage (grain meal in the amount of 95-98 wt.% And crushed biodegradable composite film 2-5 wt.%), Allows you to get plates with a diameter of 10-30 cm with well-formed raised edges. Samples of utensils have a flat, dense, shock-resistant, slightly rough surface that does not change its properties in contact with food.

An essential distinguishing feature of the claimed invention is that for the production of biodegradable tableware, a mixture of components is used, which consists of food waste (grain meal) with a particle size of 0.02 to 3.00 mm in an amount of 95-98 wt%, moisture content is not more than 9% and crushed biodegradable composite film, in an amount of not more than 2-5 wt.%, i.e. in general, the initial mixture does not contain synthetic materials.

To obtain a biodegradable composite film, first, stirring is carried out using a mechanical stirrer at a speed of 120 rpm for 5 minutes a mixture of starch and sodium alginate dissolved in distilled water, taken in a ratio of 5: 1, at the end of the mixing process, add 1-5 parts of glycerin ... The resulting suspension is treated with ultrasonic action (USV) on a Volna device, model UZTA-0.63 / 22-ОМ, at a frequency of 22 ± 1.65 kHz and an exposure power of 630 W for 5 minutes in a cooling system at a temperature of 28 ± 4 ° C. The solution obtained after exposure to USV is heated in a water bath with stirring at a temperature of 80-90 ° C and the solution is cooled to a temperature of 50 ° C. Films are formed using the method of pouring onto a glass surface with subsequent distribution of the solution over the surface, dried at a temperature of 20-25 ° C. An ice bath is used as a cooling system, where a container with a solution to be treated is placed, while the temperature of 28 ± 4 ° C is controlled by a thermometer placed in the liquid to be treated.

Grain meal is a peeling product of cereal crops containing fruit and seed coats, as well as an aleurone layer, formed as a by-product in the production of flour, cereals and other types of food products.

A biodegradable composite material (film) based on plant biopolymers is obtained with the following ratio of components, wt%:

potato starch 4.2-5.0, sodium alginate 0.1-0.8, glycerin 5.0-20.0, distilled water - the rest.

Starch is a mixture of polysaccharides (amylose and amylopectin), the monomer of which is alpha-glucose. Starch is synthesized by different parts of plants in chloroplasts and fluctuates in different proportions. Sources of starch include potatoes - 24%, rice - 75%, corn - 70%, wheat - 64% starch. Potato starch is one of the most common polysaccharides used as a stabilizer and thickener in food production. Potato starch has a high swelling rate and a low gelatinization temperature. The physical and mechanical properties of films based on potato starch depend on the ratio of crystalline and amorphous forms [3].

Glycerin (1,2,3-propanetriol) is responsible for the plasticity and flexibility of the films. With its lack, the films do not stretch; when bent, they easily break. With an excess of glycerin, the films are poorly separated from the surface, become sticky, viscous.

To improve the quality of films based on potato starch, additional film-forming substances (sodium alginate) are added. Sodium alginate is a water-soluble salt of alginic acid found in all types of brown algae. It has enhanced film-forming properties due to its unique colloidal properties, which include the stabilization of emulsions, the formation of suspensions and gelation, thereby finding wide application in the food industry [2,4].

The granulometric composition of the grain meal (Table 1) should have a particle size of 0.2 to 3.00 mm, which ensures maximum adhesion of the material. For grinding, a LZM1M mill is used. In the presence of larger particles, the surface of the dishes loses its uniformity, acquires an increased roughness, and separate delaminated areas stand out. The presence of only a small particle size leads to a loss in the strength characteristics and impact resistance of the dishes when dropped.

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Table 1

Averaged results of determining the grain size distribution of grain meal by sieve analysis

Particle size, μm Fraction share,% up to 900 1-8 1000 12-20 2000 65-83 3000 3-6

The moisture content of the grain meal should be no more than 9%, the maximum moisture reduction is preferable, but this usually requires additional equipment and energy costs, which is not cost-effective from the point of view of economic efficiency of development. The use of grain meal with a moisture content of more than 9% leads to an uneven surface of products due to a sharp transition of moisture contained in the raw material into a vaporous state during pressing of products at elevated temperature and pressure.

The use of the temperature of heating the mixture in the mold before pressing in the range (120-160) ° C is due to the fact that lower values (less than 120 ° C) do not allow melting of the crushed biodegradable composite film used in the mixture, which sharply reduces the strength characteristics of the products. Whereas the temperature is higher than 160 ° C leads to burning of the surface of the molded products.

The conditions for obtaining a biodegradable composite material are due to the following factors.

The use of these modes of mixing a mixture of starch and sodium alginate (120 rpm for 5 min) allows to obtain the most homogeneous structure of the suspension, and subsequently the film. The lower intensity and duration of exposure leads to the formation of compacted clots, an inhomogeneous structure of the film, reduces its elasticity and strength characteristics. The high intensity and duration of the impact is inexpedient from an economic point of view.

It is also essential to treat the solution by ultrasonic action (USV) with a power of 630 W, at a frequency of (22 ± 1.65) kHz for 5 minutes in a cooling system at a temperature of (28 ± 4 ° C). It is known that the cavitation disintegration of food media is due to the magnitude of the pressure reached on the surface of the bubbles when they are compressed to a minimum volume relative to the state of rest (collapse). Due to ultrasonic treatment, structural changes occur in the matrix of the composite. USV contributes to the production of homogeneous suspensions of the film solution, accelerates the processes of cross-linking of components [1,5].

The applied power of exposure (630 W) is due to the maximum technical characteristics of the device, and the duration of exposure (5 min in the cooling system (28 ± 4) ° С) allows obtaining the lowest viscosity of solutions (142.8 ± 25) mPa-s and forming thin , homogeneous in composition, elastic film, well crushed to a given granulometric composition.

The specified heating temperature range (80-90 ° C) and its duration (no more than 5 minutes) is due to the selection of optimal parameters for the technological operation - starch crystallization (gelation process), with less temperature and time exposure, the gelation process does not occur, and with greater impact - excessive thinning of the system is observed, which reduces the strength characteristics of the films.

The granulometric composition of the biodegradable composite material (Table 2) to a particle size of 0.01-3.20 mm (when using the LZM-1M mill) is necessary for its uniform distribution in the composition of the mixture, the presence of a larger particle size significantly complicates this process, and grinding it is not expedient from an economic point of view to the minimum characteristics and leads to significant losses during mechanical stirring of the mixture as a result of settling on the walls of the container.

table 2

Averaged results for determining the granulometric composition of a biodegradable composite material

Particle size, μm Fraction share,% 10-100 12 101-1500 22-40 1501 -2500 45-63 2501 -3200 5-6

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Example.

A mixture of grain meal with a particle size of 0.2 to 3.00 mm and a moisture content of not more than 9% in an amount of 95-98 wt% and a crushed biodegradable composite film based on natural biopolymers with a particle size of 0.01 to 3.20 mm in the amount of 2-5 wt.% is thoroughly mixed until a homogeneous composition is obtained. Then the mixture is placed in the lower part of the metal mold, the mixture is leveled by vibration and molded after closing with the upper part of the metal mold with the formation of a gap between the edges of the mold 0.3-0.5 mm, connected to a hydraulic press, pressure 2060 tons, at a temperature of 120- 160 ° C. After that, the pressure is released, the mold is opened and the shaped dishes are removed.

The following ratios of components were used to obtain biodegradable cookware.

Sample 1 - a mixture of grain meal: crushed biodegradable composite film in a ratio of 98: 2.

Sample 2 - a mixture of grain meal: crushed biodegradable composite film in a ratio of 97: 3.

Sample 3 is a mixture of grain meal: crushed biodegradable composite film in a ratio of 96: 4.

Sample 4 is a mixture of grain meal: crushed biodegradable composite film in a ratio of 95: 5.

Table 3

Physical and mechanical indicators Sample 1 Sample 2 Sample 3 Sample 4 Thickness, mm 3.5-4.6 3.0-4.5 3.5-4.4 3.5-4.8 Stiffness, MPa 980 1350 1620 1830

Based on the results presented in table. 3, it can be concluded that the obtained samples of biodegradable tableware have good stiffness indicators, and with the introduction of a larger amount of crushed biodegradable composite film, this characteristic increases. But with a ratio of grain meal: crushed biodegradable composite film of 95: 5, the appearance of pronounced surface defects (ribbing, swelling of individual surfaces, etc.) is observed, on the basis of this fact, 3 and 4 were selected as optimal samples.

The dishes are capable of completely disintegrating into separate structural elements. The specified material for the manufacture of dishes can serve as material for the development of compost. When determining the degree of development of molds on the material, it was found that it contains a sufficient amount of nutrients that favor the development of fungi.

In addition, the composition of the proposed tableware does not contain synthetic materials and it can be concluded that the tableware made according to the proposed method is capable of self-biodegradation under the influence of natural factors.

List of used literature.

1) Bezzubov, A.D. Ultrasound and its application in the food industry / A.D. Bezzubov, E.I. Garlinskaya, V.M. Fridman. - Moscow: Publisher: Food Industry, 1964. - 196 p.

2) Zakirova, A.Sh. The influence of enzymatic treatment of potato starch on the physicomechanical properties of biofilms / A.Sh. Zakirova, T.N. Mana-khova, A.V. Kanarsky, Z.A. Kanarskaya // Bulletin of Kazan Technological University. - 2013. - T. 16. - No. 6. - S. 117-120.

3) Krutko, E.T. Technology of biodegradable polymer materials / E.T. Krutko, N.R. Prokopchuk, A.I. Globa. - Minsk: Publisher: BSTU, 2014.-105 p.

4) Borcharda, W. Phase diagram of the system sodium alginate / water: A model for biofilms / W. Borcharda, A. Kenninga, A. Kappa, C. Mayerb // International Journal of Biological Macromolecules - 2005. - V. 35. - No. 5. P. 247-256.

5) Usachev Ivan. Usage of thermoplastic starch and ultrasound in development of biodegradable polymer film / Ivan Usachev, Alexander Papahin, Valentina Kolpakova, Nikolay Lukin, Vladimir AnanievZ / Proceedings of the International Multidisciplinary Scientific Ge-oConference SGEM. -2018. - V. 18. -P. 1019-1025.

Claims (1)

CLAIM A method for the production of biodegradable dishes from a mixture of components by molding said mixture in a mold under heating and under pressure, and for the mixture a powdery composition of grain meal with a particle size of 0.2 to 3.00 mm in an amount of 95-98 wt.% Is used, having a moisture content of not more than 9%, and a crushed biodegradable film in an amount of 2-5 wt%, the latter consists of the following components, wt%: potato starch from 4.2 to 5.0, sodium alginate from 0.1 to 0, 8, glycerin from 5.0 to 20.0, distilled water - the rest; to obtain a film, these components are thoroughly mixed, treated with ultrasound, heated in a water bath to a temperature of 80-90 ° C, cooled to a temperature of 50 ° C, the film is formed by pouring onto a glass surface and dried at a temperature of 20-25 ° C, then the resulting film is crushed to a particle size of 0.01 to 3.20 mm; a powdery composition of grain meal and biodegradable film is leveled in the lower part of a metal mold, consisting of two parts, by vibration for 0.2-0.5 minutes, then the mold is covered with its upper part, created by connection with a press force ranging from 20 to 60 tons, at a temperature of 120-160 ° C, then the mold is opened slightly, the pressure is reduced to atmospheric and the finished dishes are removed.