EA009416B1 - Methods for the production of polymer compositions and polymer compositions as aqueous suspension and dried powder - Google Patents

Abstract

The invention relates to obtaining products containing a modified vegetable raw material which can be used for the wood industry, building, for producing drill fluid, in the paper industry and the similar.The inventive method comprises a liquid-phase catalytic oxidation of the vegetable raw material by oxygen in aqueous alkali solutions in the presence of a copper. The step-by-step introduction of alkali in a reaction medium makes it possible to stabilise oxidation conditions, wherein the vegetable raw material dissolution rate is equal to or less than a starch oxidation rate. The end oxidation products are embodied in the form of aqueous suspension and dried powder polymer compositions containing water-soluble and water-insoluble components at the mass ratio thereof of (73.5-92.5): (6.5-21.5).

Description

The invention relates to methods for producing polymer compositions containing modified components of plant materials, which can be used in the woodworking industry, construction, in drilling, paper industry and other industries.

The invention relates to the production of viscous stable stable aqueous polymer dispersions by liquid-phase oxidative modification of plant materials, which can be dried to obtain a powder of a water-soluble polymer.

State of the art

At present, a multi-stage energy-intensive process of obtaining technical products from plant materials is widely used, including the stages of preliminary isolation of its individual components (starch, cellulose, fats, lignins) and the stage of subsequent modification of the selected component to obtain chemicals with desired properties. Thus, a method is known for producing carboxymethyl cellulose sodium salt from plant material, which includes the steps of isolating cellulose from wood, producing alkaline cellulose and monochloracetic acid, cellulose etherification with monochloracetic acid, and drying. The known method is characterized not only by multi-stage, but also by the use of highly toxic compounds, including chlorine at the stage of production of monochloracetic acid.

It is known that, despite the wide variety of available types of natural starches, their properties do not always satisfy consumer requirements, which determines the demand for various modified starches disclosed, for example, in Mobyeb 81tsyek: Rtoreyek apb Ikek, Eb. Huig / bigd. SRS Rgekk, 1ps., E1oyba, as well as in patent applications UO 02/074814, UO 02/077035, UO 00/75192.

In the patent I8 3975206, cl. C08B 31/18 discloses a method for producing modified starches by oxidizing the latter with hydrogen peroxide at a pH of 4-5, resulting in the formation of water-soluble starches. There is also a method for producing oxidized starch by simultaneously treating the initial starch in suspension as two oxidizing agents simultaneously: alkali metal hypohalide and oxygen in an alkaline medium at a pH of 9-12 (8ca11e1 Century B., 8o ^ e11 EA 81atst Syeskyu apb Teslaodo. Ν .2, 1pbik1pa1 Akres1k, Ebk V.V., 1967. 237 p.). There are also known methods for the oxidation of dry or wet starch with ozone (UO 97/32902, class C08B 31/18 Me1ob Got oh | b | xhd bgu k1agy iktd okhope) or sodium hypochlorite (KaShoisy E., Ta \\ TP <8. 81at. 1998. N 2-3. R. 114-119).

In patent EP 0548399, cl. C08B 31/18 discloses a method for producing acids from carbohydrates by the method of catalytic modification of polysaccharides with molecular oxygen. The known method involves a preliminary stage of extraction of plant polysaccharide. A serious limitation of the known method for the catalytic oxidation of carbohydrates by molecular oxygen is not only the high cost of polysaccharide (starch, dextrins) in industrial production, but also the incomplete use of all components of plant materials. In addition, the product obtained in a known manner is a heterogeneous solution that does not have viscous flow properties.

Disclosure of invention

In the framework of this invention, the task of developing such a method of oxidative modification of plant materials is solved, which would make it possible to obtain environmentally friendly cheap chemicals from plant materials in one step, containing both products of polysaccharide modification and all other components of plant materials. There is a need to obtain reagents with viscous flow properties and suitable for use in various fields of technology. There is also a need to reduce the duration of the oxidative modification of plant materials and increase its stability.

The problem is solved in that in the method for producing a polymer composition in the form of a stable aqueous suspension, liquid-phase oxidative treatment of plant materials in an alkaline medium is carried out in the presence of an aqueous solution of divalent copper salt at a temperature from the range of 50-80 ° C under aeration and mixing conditions, so that the alkali introduced into the reaction mixture in two stages, first in an amount of 5-10 wt.% with respect to the weight of plant materials, and then in an amount of 0.5-2 wt.% with respect to the weight of plant materials 1-1.5 hours after in eating the first portion to obtain a suspension containing a water-soluble component based on carboxyl-containing derivatives of carbohydrates, low molecular weight fatty acids, low-substituted cellulose ethers and alkali metal salts of carboxycellulose, a water-insoluble component based on polysubstituted cellulose ethers and partially hydrolyzed protein, and an aqueous medium the ratio of soluble and insoluble components in the range of (73.5-92.5) :( 6.5-21.5), respectively.

It is preferable to carry out liquid-phase processing of plant materials to achieve a viscosity of the suspension from the range of 100-6000 cP at a temperature of 20 ° C.

The problem is also solved by the fact that in the method for producing a polymer composition in the form of a dried powder, an aqueous suspension is preliminarily prepared by liquid-phase oxidative treatment of plant materials in an alkaline medium in the presence of an aqueous solution of two salt

- 1 009416 valence copper at a temperature in the range of 50-80 ° C under aeration and stirring conditions, so that the alkali is introduced into the reaction mixture in two stages, first in an amount of 5-10 wt.% With respect to the weight of the plant material, and then in the amount of 0.5-2 wt.% with respect to the weight of plant materials 1-1.5 hours after the introduction of the first portion to obtain a suspension containing a water-soluble component based on carboxyl-containing derivatives of carbohydrates, low molecular weight fatty acids, low substituted cellulose ethers and salts of alkaline m talla carboxycellulose, a water-insoluble component based on polysubstituted cellulose ethers and partially hydrolyzed protein, and an aqueous medium, with a mass ratio of soluble and insoluble components in suspension in the range (73.5-92.5) :( 6.5-21.5), respectively and carry out subsequent drying of the suspension.

The problem is solved in that in the polymer composition in the form of a stable aqueous suspension exhibiting viscous flow properties and containing a water-soluble component based on carboxyl-containing derivatives of carbohydrates, low molecular weight fatty acids, low-substituted cellulose ethers and alkali metal salts of carboxycellulose, as well as a water-insoluble component based on polysubstituted cellulose ethers and partially hydrolyzed protein, and aqueous medium, mass ratio of soluble and insoluble components s is in the range (73,5-92,5) :( 6,5-21,5), respectively, and the total solids content in the suspension is 10-50 wt.% of the slurry.

Preferably, the aqueous suspension has a viscosity in the range of 100-6000 cP at a temperature of 20 ° C.

The problem is also solved by the fact that in the polymer composition in the form of a dried powder containing a water-soluble component based on carboxyl-containing derivatives of carbohydrates, low molecular weight fatty acids, low-substituted cellulose ethers and alkali metal salts of carboxycellulose, and a water-insoluble component based on polysubstituted cellulose ethers and partially hydrolyzed protein, the mass ratio of soluble and insoluble components is in the range (73.5-92.5) :( 6.5-21.5) corresponding nno.

The essence of the invention consists in the implementation of the process of liquid-phase catalytic oxidation of plant materials in an aqueous alkaline medium in the presence of divalent copper salts by identifying the thermodynamic and kinetic laws of formation of polymer products of modification of plant materials using all its components. The final product of the oxidative modification of plant materials is viscous polymer stable aqueous suspensions containing a complex of modified components of plant materials. Due to the lack of a rigorous theory of the viscosity of dispersion systems and polymer solutions, the above regularities in the formation of polymer products of modification of plant materials were carried out empirically.

Plant materials are inert with respect to molecular oxygen and practically do not oxidize under mild conditions using traditional catalytic systems. However, it was found that the catalytic system (plant materials + alkali + copper complexes) under certain conditions is capable of catalyzing abnormally high rates of low-temperature oxidation of all components of plant materials, a number of ketones, alcohols and polyols with molecular oxygen. The resulting oxidative modification product of plant materials is a polymer composition in the form of a stable aqueous suspension having viscous flow properties.

The invention provides dried powders capable of being redispersed in water to form a stable aqueous suspension. The powder can be obtained by preparing stable aqueous dispersions according to the invention and drying the dispersion. Dispersions can be dried by various means, since there is a slight tendency to stick particles even at extreme temperatures. Such drying means include spray drying, drum drying, flue-gas drying, and vacuum drying, including freeze-drying.

As plant raw materials, not only conditioned raw materials can be used, but also agricultural waste, including waste generated by grinding rice.

Polysaccharides (starch, cellulose, pectin substances) are the main components of almost any plant material, including agricultural waste. It was found that starch is actively oxidized by molecular oxygen only in the presence of homogeneous catalysts and alkalis.

Studies have shown that carbohydrates (poly- and monosaccharides) contained in plant materials are also easily oxidized by molecular oxygen in the presence of bases and homogeneous catalysts to form water-soluble polyoxycarboxylic acids.

As is known, in addition to polysaccharides, fats, proteins and lignins are present in significant quantities in plant materials. It was found that fats are easily hydrolyzed by alkali to form glycerol and salts of fatty acids, which do not undergo further transformations. At the same time, glycerol and salts of fatty acids formed as a result of alkaline hydrolysis of fats can significantly improve the surface-active and lubricating properties of aqueous suspensions

- 2 009416 modified plant materials in comparison, for example, with the oxidation products of pure starch.

A study of the catalytic oxidation of lignin in an alkaline medium showed that lignin readily undergoes oxidative modification under these conditions with the formation of reactive oxoaromatic and quinone-containing compounds.

Studies have shown that proteins in the presence of alkali and catalyst are also modified by molecular oxygen as a result of complex chemical transformations. It was experimentally established that under the action of alkali, hydrolysis of peptide bonds occurs with the formation of amino acids. In addition, the catalytic oxidation of Ν-H protein groups proceeds, which significantly accelerates the destruction of the polypeptide. In the presence of an oxidized polysaccharide, Ν-H groups of amino acids interact with the carbonyl groups of the modified carbohydrate, and the physicochemical properties of the latter change significantly: the cation exchange capacity increases and the water loss of aqueous suspensions decreases compared to the polysaccharide modified in the absence of proteins.

It was also found that a protein in an alkaline environment is able to interact effectively with a catalyst, ultimately causing the deactivation of the latter. For this reason, the conditions for the production of viscous flowing chemicals containing products of modification of all components of plant materials, including polysaccharides, by carrying out the process of modifying plant materials containing large amounts of protein other than during the oxidation of pure polysaccharides.

Under the conditions of the process of modification of plant materials other than those stated, hydrolysis and oxidation of proteins occur, and active nitrogen-containing derivatives accumulate in the system, causing rapid catalyst deactivation. As a result, the polysaccharides present in plant materials are practically not involved in the oxidation process. Water suspensions even after 10-20 hours of treatment remain highly viscous, and when cooled to room temperature they become practically non-fluid. As a result of this, there was a need to select such conditions for the modification of plant raw materials containing protein under which the rate of oxidation of polysaccharides would be significantly higher than the rate of hydrolysis and oxidative destruction of the protein. Such conditions are achieved, first of all, by introducing alkali into the reaction mixture in two stages, efficient gas and mass transfer, and carrying out the process of modifying plant materials at relatively low temperatures (not higher than 80 ° C).

It was also found that one of the essential parameters that determine the properties of the obtained polymer suspensions of modified plant materials is the amount of alkali added. With the introduction of 10 kg of alkali per 1 ton of grain, a highly viscous, practically non-fluid suspension at room temperature is formed (with a solids content of 15-20 wt.%). With the introduction of alkali in an amount of 200-300 kg per 1 ton of grain, ceteris paribus, you can get a low viscosity suspension. However, the preparation of suspensions with a viscosity close to that of water is not the subject of this invention, as they do not provide the required structural and mechanical properties of the polymer composition.

The optimum temperature of the process of modification of plant materials is 50-75 ° C. However, if it is necessary to obtain highly concentrated suspensions with a solids content of more than 25 wt.%, The modification process at these temperatures may not be efficient enough due to poor mass transfer. In this case, an increase in temperature to 80 ° C can significantly intensify the reaction of catalytic oxidation of plant materials.

On the other hand, studies have shown that carrying out the process at temperatures above 80 ° C, as a rule, leads to the formation of a substandard product. This is due to the fact that a significant increase in temperature reduces the rate of oxidation of polysaccharides, and at the same time the processes of non-catalytic conversion of plant materials are sharply intensified: caramelization of starch, protein denaturation, etc. These processes are accompanied by catalyst deactivation. As a result, salts of polyoxyacids from starch are practically not formed, the solutions of which have hundreds of times lower viscosity in comparison with unoxidized starch. As the starch grains dissolve, the resulting suspension thickens, gas exchange decreases, which can lead to a complete cessation of the catalytic oxidation reaction.

The developed method of oxidative modification of plant materials allows to obtain aqueous suspensions with a solids content of from 10 to 50 wt.%, While avoiding the difficulties associated with the extremely high viscosity of aqueous solutions of starch-containing raw materials. Vegetable raw materials in the presence of sodium or potassium hydroxides after short mixing also gives a dense mass at temperatures above 50 ° C, which is almost impossible to undergo oxidative processing. However, starch contained in plant raw materials in the presence of homogeneous catalysts: an aqueous solution of salts of divalent copper and alkali undergoes catalytic oxidation at a high rate, in this case the -C-C bonds in the 2,3 position of the glucoside rings break and form carboxyl groups. The result of carboxylation of starch is a sharp drop in the viscosity of its aqueous alkaline solutions. Even with modification, only 1%

- 3 009416 polymer grains, i.e. of one of hundreds of starch glucoside units, the viscosity of solutions decreases thousands of times.

This method avoids the difficulties of working with ultra-viscous pastes. As the plant material dissolves in the alkaline solution, the viscosity of the solution gradually increases. However, at the same time, the carboxylation of the molecules of dissolved starch also proceeds, which sharply reduces its viscosity. Thus, under conditions under which the dissolution rate of plant materials does not exceed the rate of oxidation of starch contained in it, the process of catalytic modification of plant materials can be carried out without sharp fluctuations in the viscosity of the oxidizable mass.

To ensure the stability of the process of oxidative modification of plant materials, it is advisable to introduce alkali into the composition of the reaction mass in stages by fractional additives. The first portion of the alkali is administered in an amount of 5-10 wt.% In relation to the plant material, and the second portion of the alkali is administered in an amount of 0.5-2 wt.% In relation to the plant material.

Studies have shown that divalent copper compounds exhibit the highest catalytic activity in the oxidation reaction of plant materials. After dissolution of copper salts in water, addition of plant materials and subsequent introduction of alkali, mixed divalent copper complexes are formed in the system, containing starch in anionic form and protein as macroligands. It was also found that the activity of the catalyst is practically independent of the nature of the copper salts used. At the same time, the activity of the catalyst is significantly reduced in the presence of strong chelators, such as ethylenediamine or o-phenanthroline. This happens because chelators blocking coordination sphere of Cu ²⁺ ion, which eliminates the possibility of the formation of reactive Cu ²⁺ chelating {... A ^-}, where A ^- - anionic form of the substrate.

From the obtained stable aqueous suspensions, dry matter can be isolated by roller drying, drying with flue gases or salting out with acetone or alcohol, followed by drying in air.

For a better understanding of the essence of the present invention, specific non-limiting examples of the catalytic modification of plant materials in an alkaline environment in the presence of copper compounds, the final product of which is a modified plant material in the form of a viscous polymer suspension, are given below.

The best options for implementing the method.

Example 1

To obtain a polymer composition in the form of an aqueous suspension, which is a product of oxidative modification of plant materials, in a thermostated enameled or steel reactor with a capacity of 10 l, equipped with a mechanical stirrer, pour 6 l of hot water and load 12 g of catalyst Cu ₂ 8O ₄ -5H ₂ O. The solution is stirred until the catalyst is completely dissolved. After that, 1.4 kg of wheat grain or flour are poured into the reactor. Then turn on the stirrer and mix the reaction mixture. After reaching a temperature of 72 ° C with constant stirring, add the first portion of alkali ΝαΟΗ in an amount of 80 g. The mixture is actively mixed and at the same time oxygen or air begins to bubble. In the process of liquid-phase catalytic oxidation of plant materials maintain a temperature of 70-72 ° C. The medium pH is maintained at 10. After 1 hour after the first portion of the alkali was fed, a second portion of the alkali was fed in an amount of 30 g. The reaction mixture was continued to actively mix and sparge, maintaining the temperature at 70-72 ° C. The process of catalytic modification of plant materials is stable, without sharp fluctuations in the viscosity of the reaction mixture. The processing of raw materials is carried out for 6 hours. As a result, a polymer stable aqueous suspension with a viscosity of 500 cP is formed at a temperature of 20 ° C. The polymer suspension obtained as a result of the modification of plant materials containing a water-soluble component based on carboxyl-containing derivatives of carbohydrates, low molecular weight fatty acids, low-substituted cellulose ethers and alkali metal salts of carboxyl cellulose can be used as a reagent for processing drilling fluids or a binder in the manufacture of wood particle boards in a composition with formaldehyde resins. The mass ratio of the water-insoluble component and the water-soluble component is 20.8: 76.3.

Example 2

In a manner analogous to the catalytic oxidation of corn grain in Example 1, a polymer viscous fluid suspension is obtained, for which the following consumption of initial reagents is taken: water - 6 l, Cu ₂ 8O ₄ -5H ₂ O catalyst - 15 g, corn grain - 1.5 kg, alkali ΝαΟΗ: the first portion is 90 g, and the second portion is 40 g. The pH of the medium is maintained at 10.5.

The time of the catalytic liquid-phase treatment of plant materials is 5 hours at a temperature of 72-74 ° C and leads to a stable aqueous suspension with a viscosity of 750 cP at a temperature of 20 ° C. The resulting viscous flowing suspension has high surfactant properties and can be used as a surfactant in various industries

- 4 009416 industry, for example, in the mining industry, in the processes of enrichment of various mineral ores, as well as in the production of cardboard, paper, chipboards or plywood. The mass ratio of water-insoluble and water-soluble components is 11.5: 86.8.

Example 3

The polymer composition in the form of a viscous flowing suspension is produced by the method of catalytic oxidation of millet, as in Example 1. The consumption of the initial reagents: water — 6 l, catalyst Cu ₂ 8O ₄ —5H ₂ O — 15 g, millet — 2.5 kg, the first portion of KOH alkali — 100 g, the second portion of alkali is 100 g. The pH is maintained at 10.5. The second portion of the alkali is administered 1.5 hours after the introduction of the first portion of the alkali.

The process of catalytic oxidation of millet is carried out at a temperature of 78 ± 2 ° C. The processing time is 4 hours. The resulting polymer suspension has a viscosity of 5000 cP at a temperature of 20 ° C. The resulting suspension is dried on a roller or spray dryer to a powder state. Upon dissolution of the obtained powder, a suspension is obtained with the same properties as after discharge from the reactor.

The resulting polymer suspension has high surface-active properties and can be used as a flocculant or coagulant to purify various liquids from suspended solids. The mass ratio of water-insoluble and water-soluble components is 18.2: 79.7.

Example 4

The polymer composition in the form of a viscous flowing suspension is produced by the method of catalytic oxidation of rice grain as in Example 1, spending the following reagents: water - 6 l, catalyst Cu ₂ 8О ₄ -5Н ₂ О - 12 g, millet 1.5 kg, the first portion of alkali ΝαΟΗ - 100 g, the second portion of alkali is 20 g. The pH is maintained at 10.7. During the oxidative catalytic treatment of rice grain, the temperature is maintained within 70 ± 2 ° C. The processing time is 3.5 hours. The oxidative modification of rice grain in an aqueous alkaline medium results in a suspension with a viscosity of 250 cP at a temperature of 20 ° C. Oxidative modification of rice grain occurs in the absence of sharp fluctuations in the viscosity of the reaction mass. The mass ratio of water-insoluble and water-soluble component is 8.1: 89.5.

The resulting suspension has high adhesive properties and can be used as an adhesive in the manufacture of corrugated board and various types of wood boards.

Dry stable reaction products of the catalytic oxidation of plant materials in the form of a powder obtained by drying aqueous suspensions according to the invention provide several advantages. In particular, powders are able to redisperse if added to water. This leads to a number of commercial advantages, including the ability to receive and store a dry product, which can later be conveniently redispersed later. Dry, redispersible products reduce the cost of transported materials, as they lack water. Dried powders are convenient to transport, and they can be redispersed in water if an aqueous suspension is needed. The invention makes it possible to store a dry product for a long time, during which it could not be stored in the form of a stable liquid dispersion. Obtained by processing plant materials, polymer compositions in the form of aqueous suspensions exhibiting viscous flow properties or dried powders have fungicidal properties and can be stored without changing their properties for a year.

Industrial applicability

The invention can be used in the manufacture of polymer compositions, which can be used as effective adhesives, lubricants and filtration reducers for drilling fluids, as well as for other compositions with other end uses. Aqueous polymer dispersions and powders obtained according to the invention contain a complex of modified components of plant materials and are characterized by unique properties that are valuable for use in the manufacture of chipboards as a binder.

The use of the method of liquid-phase oxidation of plant materials in an alkaline medium in the presence of a catalyst, which is used as aqueous solutions of divalent copper compounds, accompanied by the modification of all components of plant materials, reduces the duration of the technological process for producing technical products containing modified components of plant materials.

Claims (6)

1. A method of obtaining a polymer composition in the form of a stable aqueous suspension, including liquid-phase oxidative treatment of plant materials in an alkaline medium in the presence of an aqueous solution of a salt of divalent copper at a temperature from a range of 50-80 ° C under aeration and stirring conditions, so that the alkali is introduced into the reaction mixture in two stages, first in an amount of 5-10 wt.% in relation to the weight of plant material, and then in an amount of 0.5-2 wt.% in relation to the weight of plant material 1-1.5 hours after the introduction of the first portion receiving with a suspension containing a water-soluble component based on carboxyl-containing derivatives of carbohydrates, low molecular weight fatty acids, low-substituted cellulose ethers and alkali metal salts of carboxycellulose, a water-insoluble component based on polysubstituted cellulose ethers and partially hydrolyzed protein and an aqueous medium, with a mass ratio of water to water solubility components in the range (73.5-92.5) :( 6.5-21.5), respectively. 2. The method according to claim 1, characterized in that the liquid-phase processing of plant materials is carried out until the viscosity of the suspension is reached from the range of 100-6000 cP at a temperature of 20 ° C. 3. A method of obtaining a polymer composition in the form of a dried powder, comprising pre-preparing a stable aqueous suspension by liquid-phase oxidative treatment of plant materials in an alkaline medium in the presence of an aqueous solution of divalent copper salt at a temperature from the range of 50-80 ° C under aeration and mixing conditions, so that alkali is introduced into the reaction mixture in two stages, first in an amount of 5-10 wt.% in relation to the weight of plant material, and then in an amount of 0.5-2 wt.% in relation to the weight of plant material 1-1.5 hours after the introduction of the first portion to obtain a suspension containing a water-soluble component based on carboxyl-containing derivatives of carbohydrates, low molecular weight fatty acids, low substituted cellulose ethers and alkali metal salts of carboxycellulose, a water-insoluble component based on polysubstituted cellulose ethers and partially hydrolyzed protein, and the aqueous medium, with the mass ratio of water-soluble and water-insoluble components in suspension in the range (73.5-92.5) :( 6.5-21.5), respectively, and the last going drying the suspension. 4. The polymer composition in the form of a stable aqueous suspension exhibiting viscous flow properties and containing a water-soluble component based on carboxyl-containing derivatives of carbohydrates, low molecular weight fatty acids, low-substituted cellulose ethers and alkali metal salts of carboxycellulose, a water-insoluble component based on polysubstituted partially hydrolyzed cellulose ethers and , and the aqueous medium, while the mass ratio of water-soluble and water-insoluble components is Range (73,592,5) :( 6,5-21,5), respectively, and the total solids content in the suspension is 10-50 wt.% of the slurry, the composition prepared by the method of claim 1. 5. The composition according to claim 4, characterized in that the aqueous suspension has a viscosity in the range of 100-6000 cP at a temperature of 20 ° C. 6. A polymer composition in the form of a dried powder comprising a water-soluble component based on carboxyl-containing derivatives of carbohydrates, low molecular weight fatty acids, low substituted cellulose ethers and alkali metal salts of carboxycellulose, and a water-insoluble component based on polysubstituted cellulose ethers and partially hydrolyzed protein, the ratio of soluble and water-insoluble components is in the range (73.5-92.5) :( 6.5-21.5), respectively, while the composition is semi Chen method according to claim 3.