WO2023224593A1 - Method for producing oligosaccharide copolymers - Google Patents

Abstract

Claimed is a method for producing oligosaccharide copolymers which includes the steps of: reacting at least one polysaccharide (component 1) with at least one degrading reagent (component 2) to produce an oligosaccharide (component 3); reacting the oligosaccharide with at least one modifying reagent (component 4) to produce a modified oligosaccharide (component 5); reacting the modified oligosaccharide with at least one organic plasticizer selected from among diols, triols and polyols (component 6), at least one emulsifier (component 7), and substances containing functional groups, or a crosslinking reagent (component 8) to produce a thermoplastic oligosaccharide (component 9); reacting the thermoplastic oligosaccharide with at least one copolymerization monomer or polymer (component 10), at least one polymerization initiator (component 11) and, if necessary, minerals (component 12) and various functional additives for improving the properties of an oligosaccharide copolymer (component 13) to produce an oligosaccharide copolymer. The polysaccharide is selected from native starch derived from cereals, such as wheat, rice, barley or maize, tuberous plants, such as potato or cassava, leguminous plants, such as peas or soya beans, or a mixture thereof, and the degrading reagent is citric acid from renewable natural resources.

Description

METHOD FOR OBTAINING OLIGOSACHARIDE COPOLYMERS

The invention relates to the chemical and food industries, in particular to the production of biologically soluble plastics, which can be used for the manufacture of molded or film products for various purposes, including food, using methods traditionally used in plastic processing (extrusion, injection molding, pressing, inflation formation and the like).

In particular, the invention relates to a new method for producing copolymers of oligosaccharides, which in the present invention are thermoplastic polymers based on renewable raw materials obtained in this way, and which soften back when exposed to heat and harden when cooled.

State of the art

The relevance of the topic of the proposed invention is due to the present time. Modern climatic and social conditions of human existence require new solutions that ensure environmentally friendly production of environmentally friendly products, namely in the field of chemistry of biological and biologically soluble polymers, suitable for processing on modern equipment, and at the same time competitive, adapted to produced in large volumes and designed to have little or no negative impact on the environment.

Polysaccharides are raw materials that have the advantages of being renewable, biosoluble and available in large quantities at an economically better price.

A biodegradable, naturally occurring polymer, polylactic acid (PLA), which is the most promising degradable material, can be obtained through the polymerization of lactic acid by fermentation of plant starch. PLA has wide application prospects in daily life, packaging industry and biomedicine due to its good mechanical properties and biocompatibility.

However, the high fragility, low impact strength and high cost of this material limit its wide application.

An effective way to overcome these disadvantages is to create PLA-based composite materials to add other biosoluble materials. For example, the addition of starch produces highly efficient and inexpensive PLA/starch mixtures and expands the application of renewable resources. Adding starch to PMC allows you to obtain a certificate for home composting, that is, no special conditions for industrial composting are required.

However, the disadvantage of such compositions is a decrease in the impact strength of the resulting material.

Low molecular weight plasticizers such as polyethylene glycol (PEG) and citrate esters can improve the plasticity of PLA/starch blend materials but cannot change the immiscibility of PLA and starch. Plasticizers subsequently migrate and are not stabilized in mixtures.

The first compositions with the addition of starch were developed more than 20 years ago. Starches have been used in mixtures with synthetic polymers such as polyethylene or polypropylene as filler. Before mixing, the starch was dried to moisture less than 1% to reduce its hydrophilic nature. The compositions obtained in this way contained from 10 to 20% granulated starch, because more than this value the physical and mechanical properties of the resulting compositions are unacceptable for further processing into finished products. Moreover, it turned out that such polyolefin-based compositions only disintegrate into fragments under the influence of living organisms, and do not biologically dissolve, as expected.

Subsequent developments were carried out based on the same formula, but only by replacing polyolefins with biodegradable polyesters such as poly-hydroxybutyrate-co-hydroxyvalerate (PHBV) or poly-lactic acid. And these mixtures with granulated starch turned out to be unacceptable.

Further developments took place by mixing with thermoplastic starch (TPS). TPC was obtained by plasticizing starch by including the required plasticizer, the amount of plasticizer ranged from 15 to 25% relative to starch. Plasticization was carried out using mechanical and thermal energy. US Patent No. 5,095,054 describes the reduced crystallinity degradation state and processes for producing thermoplastic starch.

The mechanical properties of thermoplastic starch obtained from various grades of starch and plasticizers are still low. The compositions are very brittle, very brittle, elongation at break is very low. The maximum tensile strength of thermoplastic starch decreases greatly as the plasticizer level increases.

Subsequently, thermoplastic starches were subjected to exploratory studies with the aim of developing biologically soluble compositions with better physical and mechanical properties. Many sources describe various options for loading biodegradable polymers with starch, with different methods of modifying the starch, but preserving the starch granules.

The starch content in these compositions remains low, and the physical and mechanical properties are low.

The prior art document WO2018187784 discloses a biodegradable polymer composite containing polystyrene and thermoplastic amorphous starch. However, it is known that polystyrene materials are brittle, can crack when bent, and have a long process of decomposition.

From document CN101323678, a biodegradable material is known containing corn or bean starch, potato starch, modified starch, polyvinyl alcohol and PLA. The components are completely mixed, transferred to the granulator to obtain granular materials after extrusion on a twin screw extruder. In the presented technical solution, granular material is obtained, which complicates further work with it. Modified starch and polyvinyl alcohol were also used, which does not allow the use of this material for the manufacture of a wide range of products.

Document CN110564089 discloses a degradable film made from corn starch, glycerin, PLA, sugar cane and purified water. Upon receipt, soaking in PVA in a special tank and stirring with steam heating and holding in standby mode are used. The addition of sugar cane is done to increase the strength of the film. The disadvantage is that in the production process of the presented material, a long-term soaking stage is used starch-containing raw materials, which subsequently requires the removal of water at high temperatures, which reduces the quality of the resulting material.

The closest to the technical solution is document CN110358264, which discloses the manufacture of a material on the basis of which packaging products are made and which contains corn starch, PBAT, PLA, glycerin, maleic anhydride, ethylene copolymer and vinyl acetate and other additional components, such as talc , calcium carbonate, chain extender. The method includes pre-processing of raw materials, mixing, extrusion granulation and subsequent stages of film production. According to the invention, the starch is pre-treated by vacuum drying, which is a costly process and significantly increases the cost of the resulting material. In addition, granular material significantly limits further use for a wider range of products.

Thus, known technical solutions provide the production of biodegradable polymers, but they use complex and expensive technological steps, have a composition that does not provide sufficient elasticity, and have an inconvenient shape for further use for wider applications.

The objective of the invention was to create a method for producing a material from which it is possible to obtain a wider range of products from raw materials, without complex pre-processing and without high-cost stages, at the same time the material must be of high quality, safe and environmentally friendly.

The problem was solved by creating a method for producing copolymers of oligosaccharides, including the stages: (a) take at least one polysaccharide (component 1) and at least one degradation reagent (component 2);

(b) subjecting the mixture of components 1 and 2 to a thermomechanical reaction using a degradation reagent to produce an oligosaccharide (component 3);

(c) take at least one oligosaccharide modification, oxidation, or other modification reagent (component 4);

(d) obtain modified oligosaccharides (component 5) by thermomechanical reaction of the oligosaccharide and the modification reagent;

(e) select at least one organic plasticizer selected from diols, triols and polyols, for example, acetyl tributyl citrate (component 6), and at least one reagent for stabilizing emulsions of water and organic plasticizer, emulsifier (component 7), and at least one plasticizer with functional groups and/or other substances containing functional groups (component 8), containing functional groups having active hydrogen, and/or functional groups yielding such functional groups having active hydrogen by hydrolysis;

(f) obtain thermoplastic oligosaccharides (component 9) by thermomechanical reaction of the modified oligosaccharide with an organic plasticizer, emulsifier and functional group-containing substances or cross-linking reagent;

(g) selecting at least one monomer or polymer to be copolymerized, a co-monomer (component 10), and at least one polymerization initiator selected from organic diacids and compounds containing at least two identical or different, free or latent functional groups selected from functional groups of isocyanate, carbamoylcaprolactam, epoxide, halogen, acid anhydride, acyl halides, oxychloride, trimetaphosphate and alkoxysilane (component 11), and optionally include various functional additives;

(h) obtain the oligosaccharide copolymer by thermomechanical reaction of a thermoplastic oligosaccharide, a monomer or polymer for copolymerization, a polymerization initiator and, if necessary, minerals and various functional additives that improve the properties of the oligosaccharide copolymer.

In the proposed method, the entire technological process takes place continuously on one twin-screw extruder.

In embodiments of the invention, the polysaccharide is selected from the native starch of cereal plants such as wheat, rice, barley or corn, tubers such as potatoes, moss, leguminous plants such as peas, soybeans, or a mixture thereof, and the degradation reagent is citric acid from renewable natural resources.

In the proposed method at stage (b), the ratio of the destruction reagent and native starch is from 0.1:100 to 0.5:100; the process occurs in the extruder during two observation zones and depends on the screw configuration, the number of revolutions of the extruder screw and temperature.

In the claimed method, the modification, oxidation or cross-linking reagent of the oligosaccharide is selected from oxidizing agents for polysaccharides, namely: hydrogen peroxide, oxygen, ozone, bromine, chromic acid, permanganate, nitrogen dioxide and hypochlorite.

In the proposed method, in step (d), the organic plasticizer is selected from diols, triols and polyols, for example acetyl tributyl citrate; the reagent for stabilizing emulsions of water and organic plasticizer is selected from mono- and diglycerides of fatty acids (E471), glycerol esters, fatty and organic acids (E472e), lecithin, phosphatides (E322), ammonium salts of phosphatidelic acid (E442), polysorbates and derivatives (E432...E436), sorbitan esters, plasticizer selected from water, sugars such as glucose, maltose, fructose or sucrose; polyols such as ethylene glycol, propylene glycol, polyethylene glycols (PEGs), glycerin, sorbitol, xylitol and hydrogenated glucose syrups; urea, salts of organic acids such as sodium lactate, as well as mixtures of these products.

Step (d) may be omitted when performing the technology of cross-linking oligosaccharides with a plasticizer using a cross-linking reagent.

Step (f) may be absent when performing the technology of copolymerization of the modified oligosaccharide with monomers or polymers for copolymerization, polymerization initiators and, if necessary, minerals and various functional additives that improve the properties of the oligosaccharide copolymer.

Steps (a), (b) and (c), (d) can be interchanged, provided that the modification of the polysaccharides is carried out first, and then the destruction of the modified polysaccharides.

At each stage of technology (b), (d), (f), (h) the mixture is heated to a temperature from 120°C to 180°C.

In step (b), oligosaccharides are obtained by continuous thermomechanical destruction on a twin-screw extruder.

In step (d), modified oligosaccharides, eg oxidized oligosaccharides, are produced by a continuous thermomechanical reaction method in a twin screw extruder. At step (f), at least one emulsifier, a reagent for stabilizing emulsions of water and an organic plasticizer, is introduced.

At step (!), at least one plasticizer is introduced having functional groups for reaction with the modified oligosaccharides and/or functional substances for binding the modified oligosaccharide to the organic plasticizer and where the functional plasticizer is epoxidized soybean oil.

In the proposed method, the plasticizer is selected from glycerin, polyglycerol, isosorbide, sorbitan, sorbitol, trimethyl citrate and/or mixtures of these products; the plasticizer is included in the modified oligosaccharides in an amount from 10 to 100 parts by weight, preferably in an amount from 25 to 75 by weight per 100 parts by weight of oligosaccharide. The polymerization initiator is selected according to the type of compound: diisocyanates and polyisocyanates, dicarbamoyl caprolacts and diepoxides, halohydrins and organic dibasic acids, oxychlorides and trimetaphosphates, alkoxysilanes. The initiator of polymerization is Bis (t-butylperoxyisopropyl) benzene. The amount of the polymerization initiator is 0.01 to 5 parts, preferably 0.1 to 3 parts, per 100 parts of the oligosaccharide copolymer from step (h).

The technical result of implementing the invention is the production of polymers with a high content of biodegradable oligosaccharides, having excellent rheological and mechanical properties, obtained by a method in which there are no long-term, complex, economically expensive operations and reagents.

Detailed Description of the Invention Polysaccharides are the most common and inexpensive natural polymers, but, unfortunately, they cannot be processed using modern equipment - they do not have thermoplastic properties. Plasticized polysaccharides require additional mixing with other biodegradable polymers to obtain compositions that have acceptable physical and mechanical properties for the production of finished products, such as films, sheets, etc.

The most common biodegradable polymer is obtained from 100% natural raw materials - PLA. But the technology for producing PLA is very complex and the cost of the biopolymer is very high.

Mixing PLA and native starch, containing up to 14% water, is problematic, since PLA quickly destructs under the influence of high temperature and water.

The present invention describes the production of saccharide oligomers from a polysaccharide and the copolymerization of oligomers with other monomers, oligomers or polymers to obtain a copolymer with high physical and mechanical properties, biodegradable and capable of being processed into finished products using modern equipment.

To weaken the strength of hydrogen bonds between the molecular chains of polysaccharides, it is necessary to reduce the particle size of the polysaccharides or the polarity of the polysaccharide surface to increase the interaction strength between PLA and oligosaccharides.

Oligosaccharides should be chemically modified by esterification, oxidation, cross-linking and grafting to promote material compatibility of the PLA/oligosaccharide mixture.

The present invention describes a method for producing an oligosaccharide copolymer (OSC), including the following steps: 1) obtaining oligosaccharides (component 3) from polysaccharides (component 1) by the method of destruction of the latter using destruction reagents (component 2);

2) obtaining modified oligosaccharides (component 5) by chemical modification of oligosaccharides using chemical modification reagents (component 4);

3) production of thermoplastic oligosaccharides (component 9) by thermochemical reaction of modified oligosaccharides and an organic plasticizer (component 6), reagents for stabilizing emulsions of water and an organic plasticizer, emulsifiers (component 7), plasticizers with functional groups and/or other substances that contain functional groups (component 8);

4) obtaining a copolymer of oligosaccharides (component 14) by thermomechanical reaction of thermoplastic oligosaccharides, polylactide, lactide and/or other biodegradable polymers (component 10), polymerization initiators (component I), minerals (component 12) and various functional additives that improve the properties of the oligosaccharide copolymer (component 13).

The initial content of oligosaccharides in the SOS can range from 5 to 95%, preferably up to 75%. So, there are three main technological processes in this technology:

1. Obtaining the required quality of oligosaccharides.

2. Modification of oligosaccharides for this type of polymerization.

3. Technology of copolymerization of oligosaccharides.

As defined herein, the term "oligosaccharides" (OS) means carbohydrates whose molecules built from several monosaccharide residues, from 2 to 20, connected by glycosidic bonds, an exocyclic bond of the anomeric C atom of a monosaccharide with an atom of an adjacent monosaccharide residue. According to the degree of polymerization, disaccharides, trisaccharides, tetrasaccharides, etc. are distinguished.

Oligosaccharides may include residues of one monosaccharide, homooligosaccharide, or various monosaccharides, hetero-oligosaccharides. Each monosaccharide residue can be in one of four possible cyclic forms (a- and -furanose, a- and p-pyranose) and is connected by a glycosidic bond to the hydroxyl group of the adjacent residue, including the hemiacetal hydroxyl. It follows that even from two identical hexoses it is possible to construct 30, and from two different hexoses - 56 isomeric disaccharides; three different hexoses theoretically give 4896 isomeric trisaccharides; with increasing degree of polymerization, the number of possible isomers quickly reaches large values.

If in an OS molecule all glycosidic bonds are formed by the hemiacetal hydroxyl of one and the alcohol hydroxyl of another monosaccharide residue, one unsubstituted hemiacetal hydroxyl remains at the end of the chain, due to which OS exhibits the properties of carbonyl compounds characteristic of monosaccharides, oxidation and reduction reactions, mutarotation and others, such OS is called restorative.

If one of the monosaccharide residues in an OS molecule is linked by a glycosidic bond to the hemiacetal hydroxyl of another monosaccharide, such OS do not contain a hemiacetal hydroxyl and are called non-reducing. ORs in which no more than one neighboring residue is attached to the alcohol hydroxyl of each monosaccharide residue are called linear; the addition of two or more monosaccharides to the alcohol hydroxyl of the same monosaccharide residue leads to branching of the oligosaccharides. Thus, trisaccharides can already have a branched structure. Monosaccharide residues located at the ends of carbohydrate chains are called terminal. In reducing oligosaccharides, a final reduced monosaccharide and a final unreduced monosaccharide are distinguished; there are one more of them than branch points.

The strict nomenclature of the OS is quite cumbersome. The name of the oligosaccharide is formed according to the type of O-substituted monosaccharide derivatives, based on the name of the reducing unit indicating all available substituents; for unreduced oligosaccharides, the nomenclature is similar to that of glycosides. The names of linear OSs often use a sequential listing of monosaccharide residues indicating the type of bond between them. Very commonly used trivial names of OS, usually associated with the source of the substance, and methods of abbreviated recording of structures in which monosaccharide residues are designated by three letters: - letters D or L, cycle size - letters f (furanoses) or p (pyranoses), configurations of glycosidic centers - letters or; numbers in parentheses indicate the position of hydroxyl groups involved in the intermonomer bond; the direction of the glycosidic bond is indicated by an arrow (the ~ sign indicates that the monosaccharide can have - or - configurations).

Various OS are obtained, as a rule, through the reaction of partial (chemical or enzymatic) cleavage of natural polysaccharides and glycoproteins. However, there are several groups of operating systems found in in nature in a free state. The sucrose group is widely represented in plants, where it plays the role of an easily mobilizing energy reserve. In addition to sucrose, this group includes OSs formed by glycosylation of the sucrose molecule with residues of D-fructose (Fru), D-glucose (Glc) or D-galactose (Gal), as well as as a result of further partial hydrolysis of these higher oligosaccharides.

Most OS are colorless crystalline compounds, soluble in water, less soluble in polar organic solvents and insoluble in non-polar ones. Non-reducing OSs crystallize easily, while reducing OSs exist in solutions as a mixture of tautomeric forms and often crystallize with great difficulty.

OS synthesis is one of the most difficult problems in the synthetic chemistry of carbohydrates. For this purpose, numerous methods have been developed for the selective protection of hydroxyl groups in monosaccharide molecules and a number of fairly effective methods for the stereospecific construction of glycosidic bonds.

The most practical use is found in sucrose, which, in terms of annual production of more than 100 million tons, occupies one of the first places among individual organic compounds. Lactose and cyclodextrins are produced in small quantities and are used in the pharmaceutical industry. Synthetic oligosaccharides, identical to the antigenic determinants of bacterial polysaccharides, can be used in the synthesis of artificial vein antigens, which are promising for the production of specific vaccines.

According to the technology in the present invention, it is possible to use various OSs, in accordance with the degree of polymerization: disaccharides, trisaccharides, tetrasaccharides. The most preferred will be OS with the highest degree of polymerization.

The expression “polysaccharides” means high molecular weight carbohydrates, polymers of monosaccharides. Polysaccharide molecules are long linear or branched chains of monosaccharide residues connected by a glycosidic bond. Upon hydrolysis they form monosaccharides or oligosaccharides. In living organisms they perform reserve (starch, glycogen), structural (cellulose, chitin) and other functions.

The properties of polysaccharides differ significantly from the properties of their monomers and depend not only on the composition, but also on the structure and branching of the molecules. They may be amorphous or even insoluble in water.

Cellulose and chitin are structural polysaccharides. Cellulose serves as the structural basis of plant cell walls and is the most abundant organic substance on Earth. It is used in the production of paper and textiles, and as a feedstock for the production of viscose, cellulose acetate, celluloid and nitrocellulose. Chitin has the same structure, but with a nitrogen-containing side branch that increases its strength. It is found in the exoskeleton of arthropods and in the cell walls of some fungi. It is also used in many industries, including surgical needles.

The expression “destruction reagents” means reagents that, during thermomechanical interaction with polysaccharides, for example, with native starch, during hydrolysis, ensure gradual depolymerization of starch and the formation of dextrins, then maltose, and with complete hydrolysis of glucose. Destruction of starch, which begins with swelling and destruction of starch grains, accompanied by depolymerization.

The same phenomenon is observed in dextrin as the degree of thermal destruction of starch increases. As the starch molecule breaks down into smaller parts, the viscosity of dextrin solutions and its adhesive properties gradually decrease to a minimum.

It has been established that the product of the initial stage of destruction, the so-called soluble starch, has high adhesive strength. The term soluble starch is usually understood as a product of starch destruction that has the following characteristics: 1) low solubility in cold water; 2) good solubility in hot water; 3) lack of ability to restore Fehling's solution; 4) the ability to give a blue color with iodine.

Degradation of the partially crystalline native state of starch to produce thermoplastic amorphous starch can be carried out in a slightly hydrated environment using extrusion processes. Producing a molten phase from starch granules requires not only a large amount of mechanical energy and thermal energy, but also the presence of a plasticizer to eliminate the risk of starch carbonation.

The most preferred reagents for starch destruction are acids from renewable natural resources, such as citric acid.

Water is the most natural plasticizer for starch and the most used, but other molecules are also very effective, especially sugar molecules such as glucose, maltose, fructose or sucrose; polyols such as ethylene glycol, propylene glycol, polyethylene glycols (PEGs), glycerin, sorbitol, xylitol and hydrogenated glucose syrups; urea, salts of organic acids such as sodium lactate, as well as mixtures of these products.

The expression “modified oligosaccharides” refers to the chemical modification of OS, which produces structural changes and the introduction of oxygen-containing functional groups, thus affecting the physicochemical properties and making it suitable for various industrial applications. For example, oxidized OS can be widely used in the paper, textile, construction and food industries.

OS oxidation involves the oxidation of a primary or secondary hydroxyl to carbonyl or carboxyl surface groups, while the number of these groups indicates the efficiency of the modification. Oxidized OS has a lower viscosity and a tendency to destroy the structure, while at the same time higher transparency, film formation and binding properties than native starch. Oxidized OS is produced by reacting OS with a certain amount of oxidizing agent at controlled temperature and pH.

The expression “modification reagent” refers to chemical structures that affect oligosaccharides and modify them, for example, oxidizing agents for OS.

The following oxidizing agents may be used, including hydrogen peroxide, oxygen, ozone, bromine, chromic acid, permanganate, nitrogen dioxide and hypochlorite.

The use of hydrogen peroxide is preferred due to its low price, high oxidation potential and beneficial environmental qualities, such as safety of use. Disadvantages The use of hydrogen peroxide is its low reactivity towards most organic functional groups and the fact that in the presence of compounds with an electrophilic character it behaves as a nucleophile without exhibiting oxidizing properties. This unfavorable property of hydrogen peroxide is overcome by using catalysts such as metal ions: Cu(II), Fe(II), Fe(III), Co(II), Ti(III), W(VI) or V(V). The most promising catalysts for OS oxidation are copper and iron ions, especially in combination. Iron ions promote the oxidation of OS, and copper ions enhance the effect of Fe(II) ions. The mechanisms of the reaction of hydrogen peroxide with OS are very complex and depend on the reaction conditions. The higher the temperature of starch oxidation with hydrogen peroxide, the higher the content of carboxyl and carbonyl groups. The choice of a suitable catalyst, as well as its concentration, have a significant impact on the duration of the oxidation reaction and the quality of the target product. The addition of 0.5% CuSO4 is sufficient to reduce the reaction time from 72 hours to just 1 hour.

By the expression "organic plasticizer" is meant any organic molecule of low molecular weight, in other words, preferably having a molecular weight of less than 5000, in particular less than 1000, which, when incorporated into starch by thermomechanical treatment at a temperature of from 20 to 200° C., results in reducing the glass transition temperature and/or reducing the crystallinity of granular starch to less than 15%, or even to a substantially amorphous state.

The expression thermoplastic oligosaccharide means OS in an amorphous and thermoplastic state. This state is obtained by plasticizing the OS by including an acceptable plasticizer included in the OS in an amount of 15 to 25% relative to modified oligosaccharide by providing mechanical and thermal energy.

The expression “a reagent for stabilizing emulsions of water and an organic plasticizer” means substances that ensure the creation of emulsions from miscible liquids.

Emulsifiers are often added to food products to create and stabilize emulsions and other food disperse systems. This is a standard ingredient in mayonnaise and other ready-made sauces, margarines and spreads, butter, chocolate, and ice cream. Emulsifiers determine the consistency of a food product, its plastic properties and viscosity.

The most acceptable are mono- and diglycerides of fatty acids (E471), esters of glycerol, fatty and organic acids (E472e), lecithins, phosphatides (E322), ammonium salts of phosphatidylic acid (E442), polysorbates and derivatives (E432...E436), esters of sorbitan, Spen (E491...E496), esters of polyglycerol and interesterified ricinol acids (E473).

The task of the emulsifier is to connect H2O, which is in the OS, with plasticizers.

By the expression “functionalized plasticizers or functionalized substances” is meant any molecule, other than OC, binder and plasticizer, containing functional groups having active hydrogen, in other words, functional groups having at least one hydrogen atom capable of substitution, if a chemical reaction takes place between the atom containing that hydrogen atom and another reactive functional group. Functional groups having active hydrogen are, for example, functional groups hydroxyl, protic acid, urea, urethane, amide, amine or thiol. This definition also covers in the present invention any molecule other than OC, a plasticizer containing functional groups capable of producing, especially by hydrolysis, such functional groups as having active hydrogen. Functional groups which can give, especially by hydrolysis, such functional groups which have an active hydrogen are, for example, alkoxy functional groups, in particular alkoxysilanes, or acyl chloride, acid anhydride, epoxide or ester functional groups.

By "polymerization initiator" is meant any molecule containing at least two free or latent functional groups capable of reacting with molecules containing functional groups having active hydrogen, such as, in particular, a plasticizer.

The polymerization initiator can strengthen the bond in the copolymer between the plasticized OS and the second monomer or polymer, or can independently initiate this bond.

The graft polymerization method ensures the production of resins of the highest quality.

When producing ternary copolymers by graft polymerization in the presence of polymerization initiators using a single-stage, continuous method, it is possible to obtain biodegradable polymers with special properties.

Using such polymerization methods, it is possible to obtain various types of high-polymer compounds with a wide range of properties, while it is possible to obtain materials with predetermined properties. Using graft polymerization methods, it is possible to obtain polymers based on monomers that are difficult to combine using conventional copolymerization methods.

The polymerization initiator ensures the attachment of at least one part of the plasticizer to the OS and/or to the functional substance using covalent bonds.

Preferably, the method includes the step of incorporating at least one functional substance into the thermoplastic OS. In this case, in other words, when the functional substance is the introduction, the polymerization initiator used is preferably selected so that one of its reactive functional groups is capable of reacting with the reactive functional groups of the functional substance. This makes it possible for the plasticizer to be at least partially attached by covalent bonding to the functional substance. Therefore, the plasticizer must be attached to both the OS and the functional substance.

The OC copolymer technology of the present invention involves continuous production and supply of components as needed.

In the zone where the polymerization initiator is supplied in the extruder, the temperature must be sufficient to carry out the graft polymerization reaction, on the one hand, with the polymer, and on the other hand, with the functional substance of the plasticized OS.

The polymerization initiator can be selected, for example, from compounds containing at least two identical or different, free or latent, functional groups selected from functional groups isocyanate, carbamoylcaprolactam, epoxide, halogen, acid anhydride, acyl halide, oxy and alkoxysilane.

The polymerization initiator may also be an organic diacid. These may preferably be the following compounds: diisocyanates and polyisocyanates; dicarbamoyl caprolacts; diepoxides, halohydrins; organic diacids, succinic acid, adipic acid, glutaric acid, maleic acid and suitable anhydrides; trimetaphosphates; alkoxysilanes.

The appropriate amount of polymerization initiator depends in particular on the plasticizer content. The higher the amount of plasticizer introduced, the greater the amount of polymerization initiator can be.

The amount of polymerization initiator used is preferably from 0.1 to 5 parts per 100 parts of the mixture.

Polysaccharides are the native starch of cereal plants such as wheat, rice, barley or corn, tuber crops such as potatoes, monica, legumes such as peas, soybeans.

The OS plasticizer is selected from diols, tripols and polyols such as glycerol, polyglycerol, isosorbide, sorbitan, salts of organic acids such as sodium lactate, urea, acetyl tributyl citrate.

The amount of bound plasticizer in the OC copolymer can be relatively high compared to compositions with free plasticizer. The plasticizer is included in the OS, preferably from 10 to 100 parts by weight of the OS.

A plasticizer having functional groups or adding to the mixture, OS and plasticizer, substances containing functional groups, having active hydrogen or functional groups having active hydrogen, may be a polymer of natural origin, or even a synthetic polymer derived from monomers of fossil origin or a monomer from renewable natural resources.

In addition, it is possible to use not only copolymer OC containing from 5 to 95% OC, but also thermoplastic OC containing from 75 to 95% OC, which can be supplied for further copolymerization or blending with other biodegradable polymers.

OC copolymer is one that is biodegradable as defined by EN 13432, ASTM D6400 and ASTM 6868 standards.

Substances that improve the properties of the OS copolymer, components 13 and 14, may be an agent that improves or regulates conductive or insulating properties with respect to electricity or heat, impermeability, for example, to air, water, gases, solvents, fatty substances, gasolines, odors and aromatic substances selected in particular from minerals, salts and organic substances, in particular from nucleating agents such as talc, compatibilizers such as surfactants, water trapping or deactivating agents, acids, catalysts, metals, oxygen or infrared radiation, hydrophobic agents such as oils and fats, granulating agents, hygroscopic agents such as pentaerythritol, agents for conducting or dissipating heat such as metal powders, graphite and salts, and micrometric reinforcing fillers such as like clay and soot.

Substances that improve the properties of the OS copolymer can also be an agent that improves organoleptic properties, in particular: aromatic properties (fragrant substances or odor masking agents);

- optical properties (illuminators, brighteners such as titanium dioxide, dyes, pigments, color enhancers, opacifiers, matting agents such as calcium carbonate, thermochromic agents, phosphorescent and fluorescent agents, metallizing or marbling agents and anti-fog agents );

- sound properties (barium sulfate and barites); And

- tactile properties (fatty substances).

The OC copolymer improver may also be an agent that improves or regulates adhesion properties, especially adhesion to cellulosic materials such as paper or wood, metal materials such as aluminum and steel, glass or ceramic materials, textile materials and mineral materials, especially pine resin, rosin, ethylene/vinyl alcohol copolymer, fatty amines, lubricants, demolding agents, antistatic agents and anti-caking agents.

The OC copolymer improvers may also be an agent that improves the wear resistance of the material or an agent that controls its biological solubility, especially selected from hydrophobic agents such as oils and fats, anti-corrosion agents, antimicrobial agents such as Ag, Cu and Zn, degradation catalysts , such as oxocatalysts, and enzymes, such as amylases.

OS copolymers expand the range of applications of PLA and correct the main defects known for PLA, namely: - mediocre barrier effect for CO2 and oxygen;

- insufficient barrier effects for water and steam;

- insufficient heat resistance for bottle production and very insufficient heat resistance for use as textile fibers; And

- fragility and lack of elasticity in the formation of films.

OS copolymer technology allows the life and stability of the polymer to be adjusted by adjusting, in particular, its affinity for water so that it is acceptable for the projected material uses and reuse envisaged at the end of its life.

The high barrier properties of the OC copolymers according to the invention allow their use as barrier films for water, steam, oxygen, carbon dioxide, odors, fuels, automotive fluids, organic solvents and/or fatty substances, alone or in a multi-layer or multi-layer structures obtained by co-extrusion, layering or other techniques, for the field of packaging of printed media, the field of insulation or the textile field, in particular.

The OC copolymers of the present invention can also be used to enhance hydrophilic nature, electrical conductivity or microwave suitability, printability, dyeability, whether bulk colored or dyed, antistatic or anti-dust effect, scratch resistance, adhesive strength, heat weldability, sensory properties, in particular tactile and acoustic properties, water and/or steam permeability, or resistance to organic solvents and/or fuels, synthetic polymers in the context, for example, the production of membranes, films for printable electronic labels, textile fibers, containers or tanks or synthetic hot-melt films, parts produced by injection molding or extrusion.

A very important aspect for polymer packaging in the modern world is that the relatively hydrophilic nature of the OS copolymers according to the invention significantly reduces the risks of biological accumulation in the fatty tissues of living organisms and therefore also in the food chain.

Comparison of the copolymer of oligosaccharides according to the invention with compositions (mixtures) of the prior art, obtained without or with a cross-linking reagent.

Currently, modified starch manufacturers are doing a lot of development in the production of thermoplastic starch (TPS) for subsequent blending with other thermoplastic biodegradable polymers. TPC cannot be processed independently, and its use requires complex equipment to produce biologically foldable mixtures. TPC usually contains up to 80% starch and plasticizers.

In terms of physical and mechanical characteristics, SOS can be compared with mixtures obtained by a two-stage method.

At the first stage, producers receive TPK.

In the second stage, manufacturers obtain a mixture of TPC with biodegradable polymers. Typically the TNC content in the mixture is 30%.

SOS with a high OC content can also be used for mixing with other biodegradable polymers. New technology for mixing SOS with biodegradable polymers does not require complex mixing equipment.

Receiving example

The entire technological process for producing oligosaccharide copolymers takes place continuously on one twin-screw extruder. The method includes the following steps.

(a) Take at least one polysaccharide (component 1), which is selected from the native starch of cereal plants such as wheat, rice, barley or corn, tubers such as potatoes, monica, leguminous plants such as peas, soybeans, or a mixture thereof and at least one destruction reagent (component 2), which is, for example, citric acid from renewable natural resources, in a ratio sufficient for further processing.

In embodiments of the invention, a suitable ratio of degradation agent to native starch is from 0.1 to 0.5:100.

(b) Oligosaccharides are prepared by thermomechanically reacting the polysaccharide with a degrader using a continuous thermomechanical decomposition method in a twin-screw extruder (component 3). The process occurs in the extruder during two observation zones and depends on the screw configuration, the number of revolutions of the extruder screw and temperature.

In embodiments of the invention, the temperature is from 120°C to 180°C.

(c) At least one oligosaccharide modification, oxidation or cross-linking reagent (component 4) is provided. Oxidizing agents for polysaccharides are suitable for this. The following can be used oxidizing agents including hydrogen peroxide, oxygen, ozone, bromine, chromic acid, permanganate, nitrogen dioxide and hypochlorite.

The use of hydrogen peroxide is preferred.

(d) Modified oligosaccharides (component 5) are obtained by thermomechanical reaction of the oligosaccharide and the modification reagent in a ratio of 0.1:100 to 0.5:100, or other depending on the selected starch. The temperature ranges from 120°C to 180°C by continuous thermomechanical reaction method on twin screw extruder. The process occurs in the extruder during two observation zones and depends on the screw configuration, the number of revolutions of the extruder screw and temperature.

(e) Select at least one organic plasticizer (component 6) selected from diols, triols and polyols, for example acetyl tributyl citrate.

At least one reagent for stabilizing emulsions of water and organic plasticizer (component 7), an emulsifier in a ratio of 1:10 to 1:100, or another is selected depending on the water content in the starch. Emulsifiers determine the consistency of the product, its plastic properties and viscosity. The most acceptable are mono- and diglycerides of fatty acids (E471), esters of glycerol, fatty and organic acids (E472e), lecithins, phosphatides (E322), ammonium salts of phosphatidylic acid (E442), polysorbates and derivatives (E432...E436), sorbitan esters.

The task of the emulsifier is to bind NgO, which is in the OS, with plasticizers. In addition, at least one plasticizer with functional groups and/or other substances containing functional groups having active hydrogen and/or functional groups giving such functional groups having active hydrogen by hydrolysis is taken. Water is the most natural plasticizer for starch and the most used, but other molecules are also very effective, especially sugar molecules such as glucose, maltose, fructose or sucrose; polyols such as ethylene glycol, propylene glycol, polyethylene glycols (PEGs), glycerin, sorbitol, xylitol and hydrogenated glucose syrups; urea, salts of organic acids such as sodium lactate, as well as mixtures of these products.

At least one plasticizer with functional groups and/or other substances containing functional groups (component 8) containing functional groups having active hydrogen and/or functional groups yielding such functional groups having active hydrogen by hydrolysis is selected. This functional plasticizer may be epoxidized soybean oil, glycerin, polyglycerol, isosorbide, sorbitan, sorbitol, trimethyl citrate, and/or mixtures of these products.

(f) Thermoplastic oligosaccharides (component 9) are prepared by thermomechanically reacting the modified oligosaccharide with an organic plasticizer, emulsifier and functional group-containing substance or cross-linking reagent. The temperature ranges from 120°C to 180°C. At least one emulsifier, a reagent for stabilizing emulsions of water and an organic plasticizer, is introduced. The introduction of an emulsifier into a mixture of oligosaccharides and plasticizers makes it possible to bind the water present in the oligosaccharide with the plasticizers and thus improve the plasticization of the oligosaccharide and reduce the cost of the final product. This stage of technology allows the use of raw materials, polysaccharides, with a higher water content, and the installation of equipment for the production of oligosaccharide copolymers directly at the starch production plant using wet grinding technology. The amount of water in starch (starch milk) is suitable for application as a raw material for this technology may vary depending on the emulsifiers and plasticizers used, and depends on the ability to bind water with the selected plasticizer. And the choice of plasticizer also depends on the ability to react with modified oligosaccharides and subsequently favorably influence the second monomer or polymer in the oligosaccharide copolymer. At least one plasticizer is introduced, having functional groups for reaction with modified oligosaccharides and/or a functional substance for binding the modified oligosaccharide with an organic plasticizer. This functional plasticizer may be epoxidized soybean oil. The plasticizer is selected from glycerol, polyglycerol, isosorbide, sorbitan, sorbitol, trimethyl citrate and/or mixtures of these products.

In embodiments of the invention, the plasticizer is included in the modified oligosaccharides in an amount of 10 to 100 parts by weight, preferably in an amount of 25 to 75 parts by weight per 100 parts by weight of the oligosaccharide.

(g) Select at least one monomer, polymer, co-monomer for copolymerization (e.g., polylactide) (component 10), and at least one polymerization initiator (component 11), selected from organic diacids and compounds containing at least two of the same or different, free or hidden functional groups selected from isocyanate, carbamoyl caprolactam, epoxide, halogen, acid anhydride, acyl halides, oxychloride, trimetaphosphate and alkoxysilane functional groups; polyisocyanates, dicarbamoyl caprolacts and diepoxides, halohydrins and organic dibasic acids, oxychlorides and trimetaphosphates, alkoxysilanes. In one embodiment of the invention, the polymerization initiator is Bis(t- butylperoxyisopropyl benzene). The amount of the polymerization initiator is 0.01 to 5 parts, preferably 0.1 to 3 parts, per 100 parts of the oligosaccharide copolymer.

If necessary, include minerals (component 12), various functional additives that improve the properties of the oligosaccharide copolymer (component 13).

(h) An oligosaccharide copolymer (component 14) is prepared by thermomechanical reaction of a thermoplastic oligosaccharide, a monomer or polymer for copolymerization, a polymerization initiator and, if necessary, minerals and various functional additives that improve the properties of the oligosaccharide copolymer. The ratio of oligosaccharides to another monomer or polymer with which copolymerization is carried out is from 1:20 to 3:1. The process temperature ranges from 120°C to 180°C. The ratio of functional additives added to the oligosaccharide copolymer is from 1:25 to 1:3.

The stages of obtaining oligosaccharides by thermomechanical reaction of a polysaccharide with a destruction reagent and obtaining modified oligosaccharides by thermomechanical reaction of an oligosaccharide and a modification reagent can be swapped. The stage of obtaining modified oligosaccharides by thermomechanical reaction of the oligosaccharide and the modification reagent may be absent when the technology of cross-linking oligosaccharides with a plasticizer due to the cross-linking reagent is performed.

The stage of obtaining thermoplastic oligosaccharides by thermomechanical reaction of the modified oligosaccharide with an organic plasticizer, emulsifier and substances containing functional groups, or a cross-linking reagent may be absent, when the technology of copolymerization of a modified oligosaccharide with monomers or polymers, and various functional additives that improve the properties of the oligosaccharide copolymer is performed. First, modification of polysaccharides is performed, then destruction of the modified polysaccharides.

Table 1

Scheme of continuous technology in a twin-screw extruder with co-directional screw movement

table 2

Scheme of a continuous technology, which is performed first in a modification reactor and then in a twin-screw extruder with co-directional screw movement

An example of obtaining SOS.

1. Materials

Option 1

- PLA (polymer 2, 2003D; density and melting point were 1.24 g/cm3 and 160°C, respectively) was purchased from Nature Works LLC;

- PBAT - polybutylene adipate terephthalate (polymer 1), Xinjiang Blue Ridge Tunhe Chemical Industry Joint Stock Co.;

- corn starch, Interstarch company;

- Citric acid monohydrate (CA), Sinopharm Chemical Reagent Co.;

- Methylene diphenyl diisocyanate (MDI), Huntsman; concentrated aqueous composition of plasticizers and modifiers: vegetable oil polyol/citrate ester, mono & diglycerides of fatty acids, epoxy soybean oil, which is supplied by the applicant under the name PLAST 1;

- Bis (t-butylperoxy isopropyl) benzene (BIPB), Jiangyin Thousands Chemicals Co.;

Option 2

- PLA (polymer 2, 2003 D; density and melting point were 1.24 g/cm3 and 1600 C, respectively) was purchased from Nature Works LLC;

- PBAT - polybutylene adipate terephthalate (polymer 1), Xinjiang Blue Ridge Tunhe Chemical Industry Joint Stock Co.;

- wheat starch, Interstarch company; - Citric acid monohydrate (CA), Sinopharm Chemical Reagent Co.;

- Luperox A75 benzoyl peroxide powder, ArKEMA company: concentrated aqueous composition of plasticizers and modifiers: vegetable oil polyol / citrate ester, sorbitol, mono & diglycerides of fatty acids, epoxy soybean oil, which is supplied by the applicant under the name PLAST 2;

- JONCRYL ADR-4380, BASF company;

2. Receiving samples

In a twin-screw extruder, with co-directed rotation of the screws, the following are fed sequentially: a) starch and CA; b) MDI; c) LAYER 1; d) Polymer 1 and BIPB; e) Polymer 2 and functional additives.

3. Measurement of mechanical properties

Dumbbell-shaped specimens were cut and polished from 2 mm thick hot-pressed plate specimens in accordance with international standards ISO 527-2. A CMT-4204 electric tensile tester (SANS) was used to test the specimens at a tensile rate of 5 mm/min to obtain the stress-strain curve of tensile strength and elongation at break.

The mechanical properties of SOS obtained using the technology of example 1 with different mass ratios of OS show an increase in the indicator elongation at break of relatively pure PLA. The ratio of PLAST 1 to oligosaccharides is 30%. The highest elongation at break corresponds to a content of 35% OS in SOS. A slight decrease in elongation at break corresponds to a 40% OS content in SOS. Thus, a new method for producing oligosaccharide copolymer has been created, which involves obtaining the best quality materials for subsequent processing by carrying out relatively simple reaction steps. Another advantage of the method is the creation of a non-granular material, which allows expanding the range of high-quality products from the resulting polymer. The description includes possible options for components, temperature and time parameters when implementing the invention.

Claims

Formula

1. A method for producing copolymers of oligosaccharides, including the stages:

(a) take at least one polysaccharide (component 1) and at least one degradation reagent (component 2);

(b) subjecting the mixture of components 1 and 2 to a thermomechanical reaction using a degradation reagent to produce an oligosaccharide (component 3);

(c) take at least one oligosaccharide modification, oxidation or cross-linking reagent (component 4);

(d) obtain modified oligosaccharides by thermomechanical reaction of the oligosaccharide and the modification reagent (component 5);

(e) select at least one organic plasticizer selected from diols, triplets and polyols, for example acetyl tributyl citrate (component 6) and at least one reagent for stabilizing emulsions of water and organic plasticizer, emulsifier (component 7), and at least one functional plasticizer groups and/or other substances that contain functional groups (component 8) that contain functional groups having active hydrogen, and/or functional groups yielding such functional groups having active hydrogen by hydrolysis;

(!) thermoplastic oligosaccharides (component 9) are obtained by thermomechanical reaction of the modified oligosaccharide with an organic plasticizer, emulsifier and substances containing functional groups or a cross-linking reagent;

36 (g) selecting at least one monomer or polymer to copolymerize, a co-monomer (component 10), and at least one polymerization initiator selected from organic diacids and compounds containing at least two identical or different, free or latent functional groups selected from functional isocyanate, carbamoylcaprolactam, epoxide, halogen, acid anhydride, acyl halides, oxychloride, trimetaphosphate and alkoxysilane groups (component 11), and, if necessary, include minerals (component 12) and various functional additives that improve the properties of the oligosaccharide copolymer (component 13);

(h) obtain an oligosaccharide copolymer by thermomechanical reaction of a thermoplastic oligosaccharide, a monomer or polymer for copolymerization, a polymerization initiator and, if necessary, minerals and various functional additives that improve the properties of the oligosaccharide copolymer (component 14).

2. The method according to claim 1, where the entire technological process takes place continuously on one twin-screw extruder.

3. The method according to claim 1, where the polysaccharide is selected from the native starch of cereal plants such as wheat, rice, barley or corn, tubers such as potatoes, monica, legumes such as peas, soybeans or a mixture thereof, and a destruction reagent is citric acid from a renewable natural resource.

4. The method according to claim 1, where at stage (b) the ratio of the destruction reagent and native starch is from 0.1 OO to 0.5:100

5. The method according to claim 1, where in stage (b) the process occurs in the extruder during two observation zones and depends on the configuration of the screw, the number of revolutions of the extruder screw and temperature.

37

6. The method according to claim 1, where the modification, oxidation or cross-linking reagent of the oligosaccharide is selected from oxidizing agents for polysaccharides, namely hydrogen peroxide, oxygen, ozone, bromine, chromic acid, permanganate, nitrogen dioxide and hypochlorite.

7. The method according to claim 1, where in step (d) the organic plasticizer is selected from diols, triols and polyols, for example acetyl tributyl citrate; The reagent for stabilizing emulsions of water and organic plasticizer is selected from mono- and diglycerides of fatty acids (E471), glycerol esters, fatty and organic acids (E472e), lecithin, phosphatides (E322), ammonium salts of phosphatidelic acid (E442), polysorbates and derivatives (E432 ... E436), sorbitan esters, the plasticizer is selected from water, sugars such as glucose, maltose, fructose or sucrose; polyols such as ethylene glycol, propylene glycol, polyethylene glycols (PEGs), glycerin, sorbitol, xylitol and hydrogenated glucose syrups; urea, salts of organic acids such as sodium lactate, as well as mixtures of these products.

8. The method according to claim 1, where step (d) may be absent when performing the technology of cross-linking oligosaccharides with a plasticizer thanks to a cross-linking reagent.

9. The method according to claim 1, where step (f) may be absent when performing the technology of copolymerization of the modified oligosaccharide with monomers or polymers for copolymerization, polymerization initiators and, if necessary, minerals and various functional additives that improve the properties of the oligosaccharide copolymer;

10. The method according to claim 1, where steps (a), (b) and (c), (d) can be interchanged, provided that the polysaccharides are first modified and then the modified polysaccharides are destroyed.

I. The method according to claim 1, where at each stage of technology (b), (d), (f), (h) the mixture is heated to a temperature from 120°C to 180°C.

12. The method according to claim 1, where in step (b) oligosaccharides are obtained by a continuous method of thermomechanical destruction on a twin-screw extruder.

13. The method according to claim 1, where in step (d) modified, for example oxidized oligosaccharides are obtained by a continuous thermomechanical reaction method on a twin-screw extruder.

14. The method according to claim 1, where at step (f) at least one emulsifier, a reagent for stabilizing emulsions of water and an organic plasticizer, is introduced.

15. The method according to claim 1, where in step (f) at least one plasticizer is introduced, which has functional groups for reaction with the modified oligosaccharides and/or functional substances for binding the modified oligosaccharide with the organic plasticizer and where the plasticizer with functional groups is epoxidized soybean oil.

16. The method according to claim 1, where the plasticizer is selected from glycerol, polyglycerol, isosorbide, sorbitan, sorbitol, trimethyl citrate and/or mixtures of these products.

17. The method according to claim 1, wherein the plasticizer is included in the modified oligosaccharides in an amount of 10 to 100 parts by weight, preferably in an amount of 25 to 75 parts by weight per 100 parts by weight of the oligosaccharide.

18. The method according to claim 1, where the polymerization initiator is selected according to the type of compound: diisocyanate and polyisocyanate, dicarbamoyl caprolact and diepoxides, halohydrins and organic dibasic acids, oxychlorides and trimetaphosphates, alkoxys.

19. The method according to claim 1, where the polymerization initiator is Bis (t-butylperoxyisopropyl) benzene.

20. The method according to claim 1, wherein the amount of the polymerization initiator is from 0.01 to 5 parts, preferably from 0.1 to 3 parts, per 100 parts of the oligosaccharide copolymer from step (h).