Polymer polyvinyl alcohol and preparation method thereof

Abstract

The invention provides macromolecular polyvinyl alcohol, which takes a plurality of vinyl alcohol as basic monomer units and is connected through covalent bonds to form a macromolecular chain structure, a polymerization reaction is adopted to form the macromolecular chain structure, hydroxyl groups in PVA molecules are connected through a cross-linking agent to form a three-dimensional network structure, and chemical cross-linking is achieved. According to the invention, high-molecular polyvinyl alcohol is used as a raw material, and a stabilizing agent, a biodegradable polymer, a biodegradable auxiliary agent and a degradation catalyst are added in an auxiliary manner, so that the hydrothermal stability and biodegradability of the high-molecular polyvinyl alcohol are improved. The stabilizing agent, the biodegradable polymer, the biodegradable auxiliary agent and the degradation catalyst are added when the high-molecular polyvinyl alcohol component is selected; according to the invention, PVA is taken as a raw material, the hydrothermal stability and biodegradability of PVA are improved, and when the polymer polyvinyl alcohol solution is cooled, the arrangement of PVA molecular chains and the formation of crystal structures can be guided by controlling the temperatures of different parts in a temperature gradient cooling manner, so that the performance of PVA is improved.

Description

Technical Field

[0001] The invention relates to the technical field of polyvinyl alcohol, in particular to a high-molecular polyvinyl alcohol and a preparation method thereof. Background Art

[0002] Polyvinyl alcohol is an important synthetic polymer compound, and its molecular structure contains a large number of vinyl alcohol monomer repeating units. PVA is a polymer formed by polymerizing vinyl alcohol monomers. It has many unique physical and chemical properties, which make it widely used in various fields. Polyvinyl alcohol is an important chemical raw material and can be used to make polyvinyl acetal, gasoline-resistant pipes and vinylon synthetic fibers, fabric treatment agents, emulsifiers, paper coatings, adhesives and glues, etc. The polymerization methods of polyvinyl alcohol known so far include solution polymerization, bulk polymerization, suspension polymerization, emulsion polymerization, etc. The polyvinyl ester polymer obtained by polymerizing vinyl acetate can be converted into industrially useful polyvinyl alcohol by saponification reaction. Among them, persulfate, azo compound, azobisisobutyronitrile and organic peroxide are usually used as polymerization initiators to participate in the polymerization reaction. Some researchers have prepared ethylene and VAc by using methanol or tert-butyl alcohol polymerization solvents and free radical initiators with semi-hydroxyl groups. The copolymer obtained by copolymerization can provide a film with excellent surface properties after saponification reaction.

[0003] However, the existing high molecular weight polyvinyl alcohol has the following problems in the process of production and use: (1) The existing high molecular weight polyvinyl alcohol has limited hydrothermal stability. PVA easily absorbs water in a humid environment, resulting in a decrease in its performance, and thus has limited stability under humid conditions; (2) and poor biodegradability. PVA is not easy to biodegrade, causing potential pollution problems to the environment. Therefore, it is necessary to design corresponding technical solutions to solve the existing technical problems. Summary of the invention

[0004] The purpose of the present invention is to provide a high molecular weight polyvinyl alcohol and a preparation method thereof, so as to solve the technical problem that the existing high molecular weight polyvinyl alcohol has limited hydrothermal stability, PVA easily absorbs water in a humid environment, resulting in its performance degradation, and therefore has limited stability under humid conditions and poor biodegradability, PVA is not easy to biodegrade, and causes potential pollution to the environment.

[0005] To achieve the above-mentioned purpose, the present invention provides the following technical scheme: a high molecular weight polyvinyl alcohol, which uses a plurality of vinyl alcohols as basic monomer units and is connected by covalent bonds to form a high molecular weight chain structure, adopts a polymerization reaction to form a polymer chain structure, uses a cross-linking agent to connect the hydroxyl groups in the PVA molecules to form a three-dimensional network structure to achieve chemical cross-linking, and auxiliary addition of stabilizers, biodegradable polymers, biodegradation aids and degradation catalysts to improve the hydrothermal stability and biodegradability of the high molecular weight polyvinyl alcohol.

[0006] As a preferred embodiment of the present invention, the polymer chain structure of the high molecular weight polyvinyl alcohol adopts a cross-linked structure and forms a three-dimensional grid structure.

[0007] As a preferred embodiment of the present invention, the stabilizer is selected from a heat stabilizer and an antioxidant, and the ratio of the heat stabilizer to the antioxidant is 2:1.

[0008] As a preferred embodiment of the present invention, the biodegradable polymer includes starch and polylactic acid, and the two are copolymerized to improve the biodegradability of the entire system.

[0009] As a preferred embodiment of the present invention, the biodegradation aid is selected from two or more of microorganisms, enzymes and biodegradation catalysts, and the selected biodegradation aid component ratio is 1:1.

[0010] As a preferred embodiment of the present invention, the degradation catalyst uses metal oxide nanoparticles, and the metal oxide nanoparticles include zinc oxide and iron oxide. The particle diameter of the zinc oxide is 35nm-55nm, the particle diameter of the iron oxide is 60nm-90nm, and the ratio of the zinc oxide to the iron oxide is 1:3.

[0011] As a preferred embodiment of the present invention, the specific preparation steps are as follows:

[0012] Step 1: Preparation of a solution of high molecular weight polyvinyl alcohol, heating an appropriate amount of water as a solvent in a reaction kettle, then slowly adding vinyl alcohol monomer into the water and adding a stabilizer, a biodegradable polymer, a biodegradation aid and a degradation catalyst, and then stirring and mixing the solution, wherein the monomer molar concentration is controlled at 0.1 mol / L-1.0 mol / L, the solution stirring temperature is controlled at room temperature 20°C-30°C, the stirring speed is 900r / min-1200r / min, and the stirring time is controlled at 30min-60min;

[0013] Step 2: Polymerization reaction of high molecular weight polyvinyl alcohol solution, heating the solution to a certain temperature to promote the polymerization reaction of vinyl alcohol monomer, the reaction temperature is 50°C-90°C, the reaction time is 1h-3h, and the polymerization degree of PVA is controlled at 1700-2400 and the alcoholysis degree is controlled at 95%-99%;

[0014] Step 3: After the polymer polyvinyl alcohol solution is finished, the heating and stirring of the solution are stopped after the polymerization reaction is completed in the above manner, and the solution is cooled by temperature gradient cooling. The solution is introduced into a constant temperature bath, and the temperature of different parts is adjusted to form a temperature gradient. Specifically, the bottom temperature of the reactor is set to be lower and the top temperature is set to be higher. The PVA solution is gradually cooled and solidified under the action of the temperature gradient. Smaller crystals may be formed at lower temperatures, while larger crystals may be formed at higher temperatures. After the PVA solution is completely solidified and cooled, subsequent purification and treatment are carried out;

[0015] Step 4: Precipitation and passivation treatment of high molecular weight polyvinyl alcohol solution, add PVA particles and powder into water, add precipitant to induce precipitation of PVA and passivate it with passivator, wait for PVA to precipitate and passivate, use centrifuge to separate PVA precipitate from solution, wash with appropriate amount of solvent to remove residual impurities and precipitant, place the washed PVA precipitate under appropriate conditions for drying to remove excess water.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1. The present invention adds a stabilizer, a biodegradable polymer, a biodegradation aid and a degradation catalyst when selecting the high molecular weight polyvinyl alcohol component, wherein the stabilizer can improve the stability of PVA under high temperature and humid conditions and ensure hydrothermal stability. In addition, the biodegradable polymer can improve the biodegradability of the entire system, the biodegradation aid promotes the biodegradation process of PVA, and the degradation catalyst can accelerate the biodegradation process of PVA, thereby improving the hydrothermal stability and biodegradability of the high molecular weight polyvinyl alcohol through the above two aspects and reducing pollution to the use environment.

[0018] 2. In the process of producing and preparing high molecular weight polyvinyl alcohol, the present invention adopts a temperature gradient cooling method when cooling the high molecular weight polyvinyl alcohol solution. The temperature of different parts can be controlled to guide the arrangement of PVA molecular chains and the formation of crystal structure, thereby improving the performance of PVA. DETAILED DESCRIPTION

[0019] Embodiment 1:

[0020] A high molecular weight polyvinyl alcohol, which uses a plurality of vinyl alcohols as basic monomer units and is connected through covalent bonds to form a high molecular weight chain structure, adopts a polymerization reaction to form a polymer chain structure, uses a cross-linking agent to connect hydroxyl groups in PVA molecules to form a three-dimensional network structure to achieve chemical cross-linking, and auxiliary addition of a stabilizer, a biodegradable polymer, a biodegradation aid and a degradation catalyst to improve the hydrothermal stability and biodegradability of the high molecular weight polyvinyl alcohol.

[0021] The specific preparation steps are as follows:

[0022] Step 1: Preparation of a solution of high molecular weight polyvinyl alcohol, heating an appropriate amount of water as a solvent in a reaction kettle, then slowly adding vinyl alcohol monomer into the water and adding a stabilizer, a biodegradable polymer, a biodegradation aid and a degradation catalyst, and then stirring and mixing the solution, wherein the monomer molar concentration is controlled at 0.1 mol / L, the solution stirring temperature is controlled at room temperature 20°C, the stirring speed is 900 r / min, and the stirring time is controlled at 30 min;

[0023] Step 2: Polymerization reaction of high molecular weight polyvinyl alcohol solution, heating the solution to a certain temperature to promote the polymerization reaction of vinyl alcohol monomer, the reaction temperature is 50°C, the reaction time is 1h, and the polymerization degree of PVA is controlled at 1700 and the alcoholysis degree is controlled at 95%;

[0024] Step 3: After the polymer polyvinyl alcohol solution is finished, the heating and stirring of the solution are stopped after the polymerization reaction is completed in the above manner, and the solution is cooled by temperature gradient cooling. The solution is introduced into a constant temperature bath, and the temperature of different parts is adjusted to form a temperature gradient. Specifically, the bottom temperature of the reactor is set to be lower and the top temperature is set to be higher. The PVA solution is gradually cooled and solidified under the action of the temperature gradient. Smaller crystals may be formed at lower temperatures, while larger crystals may be formed at higher temperatures. After the PVA solution is completely solidified and cooled, subsequent purification and treatment are carried out;

[0025] Step 4: Precipitation and passivation treatment of high molecular weight polyvinyl alcohol solution, add PVA particles and powder into water, add precipitant to induce precipitation of PVA and passivate it with passivator, wait for PVA to precipitate and passivate, use centrifuge to separate PVA precipitate from solution, wash with appropriate amount of solvent to remove residual impurities and precipitant, place the washed PVA precipitate under appropriate conditions for drying to remove excess water.

[0026] The present invention adds a stabilizer, a biodegradable polymer, a biodegradation aid and a degradation catalyst when selecting the high molecular weight polyvinyl alcohol component, wherein the stabilizer can improve the stability of PVA under high temperature and humid conditions and ensure hydrothermal stability, and the biodegradability of the entire system can be improved by the biodegradable polymer, the biodegradation aid promotes the biodegradation process of PVA, and the degradation catalyst can accelerate the biodegradation process of PVA, thereby improving the hydrothermal stability and biodegradability of the high molecular weight polyvinyl alcohol through the above two aspects, reducing pollution to the use environment, and in the process of producing and preparing the high molecular weight polyvinyl alcohol, when cooling the high molecular weight polyvinyl alcohol solution, a temperature gradient cooling method is adopted to guide the arrangement of PVA molecular chains and the formation of crystal structures by controlling the temperatures of different parts, thereby improving the performance of PVA.

[0027] Embodiment 2:

[0028] A high molecular weight polyvinyl alcohol, which uses a plurality of vinyl alcohols as basic monomer units and is connected through covalent bonds to form a high molecular weight chain structure, adopts a polymerization reaction to form a polymer chain structure, uses a cross-linking agent to connect hydroxyl groups in PVA molecules to form a three-dimensional network structure to achieve chemical cross-linking, and auxiliary addition of a stabilizer, a biodegradable polymer, a biodegradation aid and a degradation catalyst to improve the hydrothermal stability and biodegradability of the high molecular weight polyvinyl alcohol.

[0029] The specific preparation steps are as follows:

[0030] Step 1: Preparation of a solution of high molecular weight polyvinyl alcohol, heating an appropriate amount of water as a solvent in a reaction kettle, then slowly adding vinyl alcohol monomer into the water and adding a stabilizer, a biodegradable polymer, a biodegradation aid and a degradation catalyst, and then stirring and mixing the solution, wherein the monomer molar concentration is controlled at 0.5 mol / L, the solution stirring temperature is controlled at room temperature 25°C, the stirring speed is 1050 r / min, and the stirring time is controlled at 45 min;

[0031] Step 2: Polymerization reaction of high molecular weight polyvinyl alcohol solution, heating the solution to a certain temperature to promote the polymerization reaction of vinyl alcohol monomer, the reaction temperature is 70°C, the reaction time is 2h, and the degree of polymerization of PVA is controlled at 2050 and the degree of alcoholysis is controlled at 97%;

[0032] Step 3: After the polymer polyvinyl alcohol solution is finished, the heating and stirring of the solution are stopped after the polymerization reaction is completed in the above manner, and the solution is cooled by natural cooling;

[0033] Step 4: Precipitation and passivation treatment of high molecular weight polyvinyl alcohol solution, add PVA particles and powder into water, add precipitant to induce precipitation of PVA and passivate it with passivator, wait for PVA to precipitate and passivate, use centrifuge to separate PVA precipitate from solution, wash with appropriate amount of solvent to remove residual impurities and precipitant, place the washed PVA precipitate under appropriate conditions for drying to remove excess water.

[0034] When selecting the material of the high molecular weight polyvinyl alcohol component, the present invention adds a stabilizer, a biodegradable polymer, a biodegradation aid and a degradation catalyst, wherein the stabilizer can improve the stability of PVA under high temperature and humid conditions and ensure the hydrothermal stability; in addition, the biodegradable polymer can improve the biodegradability of the entire system, the biodegradation aid promotes the biodegradation process of PVA, and the degradation catalyst can accelerate the biodegradation process of PVA, thereby improving the hydrothermal stability and biodegradability of the high molecular weight polyvinyl alcohol through the above two aspects and reducing the pollution to the use environment.

[0035] Embodiment 3:

[0036] A high molecular weight polyvinyl alcohol, which uses a plurality of vinyl alcohols as basic monomer units and is connected by covalent bonds to form a high molecular weight chain structure, adopts polymerization reaction to form a polymer chain structure, and uses a cross-linking agent to connect the hydroxyl groups in the PVA molecules to form a three-dimensional network structure to achieve chemical cross-linking.

[0037] The specific preparation steps are as follows:

[0038] Step 1: Preparation of a solution of high molecular weight polyvinyl alcohol, heating an appropriate amount of water as a solvent in a reaction kettle, then slowly adding vinyl alcohol monomer into the water, stirring and mixing the solution, wherein the monomer molar concentration is controlled at 0.5 mol / L, the solution stirring temperature is controlled at room temperature 25°C, the stirring speed is 1050 r / min, and the stirring time is controlled at 45 min;

[0039] Step 2: Polymerization reaction of high molecular weight polyvinyl alcohol solution, heating the solution to a certain temperature to promote the polymerization reaction of vinyl alcohol monomer, the reaction temperature is 70°C, the reaction time is 2h, and the degree of polymerization of PVA is 1100 and the alcoholysis degree is controlled at 86%;

[0040] Step 3: After the polymer polyvinyl alcohol solution is treated, after the polymerization reaction is completed in the above manner, the heating and stirring of the solution are stopped, and the solution is cooled by natural cooling;

[0041] Step 4: Precipitation and passivation treatment of high molecular weight polyvinyl alcohol solution, add PVA particles and powder into water, add precipitant to induce precipitation of PVA and passivate it with passivator, wait for PVA to precipitate and passivate, use centrifuge to separate PVA precipitate from solution, wash with appropriate amount of solvent to remove residual impurities and precipitant, place the washed PVA precipitate under appropriate conditions for drying to remove excess water.

[0042] According to the above three groups of examples, the high molecular weight polyvinyl alcohol was processed and 100g of the material was made into a PVA sheet with a thickness of 1 cm, and the quality of the PVA sheet made of the high molecular weight polyvinyl alcohol in each example was observed, as follows:

[0043]

[0044] According to the analysis of the above table, it can be known that when selecting the high molecular weight polyvinyl alcohol component, the present invention adds a stabilizer, a biodegradable polymer, a biodegradation aid and a degradation catalyst, wherein the stabilizer can improve the stability of PVA under high temperature and humid conditions and ensure hydrothermal stability. In addition, the biodegradable polymer can improve the biodegradability of the entire system, the biodegradation aid promotes the biodegradation process of PVA, and the degradation catalyst can accelerate the biodegradation process of PVA, thereby improving the hydrothermal stability and biodegradability of the high molecular weight polyvinyl alcohol through the above two aspects, reducing pollution to the use environment, and in the process of producing and preparing the high molecular weight polyvinyl alcohol, when cooling the high molecular weight polyvinyl alcohol solution, the temperature gradient cooling method can be used to guide the arrangement of the PVA molecular chains and the formation of the crystal structure by controlling the temperature of different parts, thereby improving the performance of PVA.

[0045] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A high molecular weight polyvinyl alcohol, characterized in that: The high molecular weight polyvinyl alcohol uses a plurality of vinyl alcohols as basic monomer units and is connected through covalent bonds to form a high molecular weight chain structure. A polymerization reaction is used to form a polymer chain structure, and a cross-linking agent is used to connect the hydroxyl groups in the PVA molecules to form a three-dimensional network structure to achieve chemical cross-linking. A stabilizer, a biodegradable polymer, a biodegradation aid and a degradation catalyst are added to improve the hydrothermal stability and biodegradability of the high molecular weight polyvinyl alcohol.

2. A high molecular weight polyvinyl alcohol according to claim 1, characterized in that: The polymer chain structure of the high molecular weight polyvinyl alcohol adopts a cross-linked structure and forms a three-dimensional grid structure.

3. A high molecular weight polyvinyl alcohol according to claim 1, characterized in that: The stabilizer is selected from a heat stabilizer and an antioxidant, and the ratio of the heat stabilizer to the antioxidant is 2:

1.

4. A high molecular weight polyvinyl alcohol according to claim 1, characterized in that: The biodegradable polymer includes starch and polylactic acid, and the two are copolymerized to improve the biodegradability of the entire system.

5. The high molecular weight polyvinyl alcohol according to claim 1, characterized in that: The biodegradation aid is selected from two or more of microorganisms, enzymes and biodegradation catalysts, and the selected biodegradation aid component ratio is 1:

1.

6. A high molecular weight polyvinyl alcohol according to claim 1, characterized in that: The degradation catalyst uses metal oxide nanoparticles, which include zinc oxide and iron oxide. The particle diameter of the zinc oxide is 35nm-55nm, the particle diameter of the iron oxide is 60nm-90nm, and the ratio of the zinc oxide to the iron oxide is 1:

3.

7. A method for preparing high molecular weight polyvinyl alcohol, characterized in that: The specific preparation steps are as follows: Step 1: Preparation of a solution of high molecular weight polyvinyl alcohol, heating an appropriate amount of water as a solvent in a reaction kettle, then slowly adding vinyl alcohol monomer into the water and adding a stabilizer, a biodegradable polymer, a biodegradation aid and a degradation catalyst, and then stirring and mixing the solution, wherein the monomer molar concentration is controlled at 0.1 mol / L-1.0 mol / L, the solution stirring temperature is controlled at room temperature 20°C-30°C, the stirring speed is 900r / min-1200r / min, and the stirring time is controlled at 30min-60min; Step 2: Polymerization reaction of high molecular weight polyvinyl alcohol solution, heating the solution to a certain temperature to promote the polymerization reaction of vinyl alcohol monomer, the reaction temperature is 50°C-90°C, the reaction time is 1h-3h, and the polymerization degree of PVA is controlled at 1700-2400 and the alcoholysis degree is controlled at 95%-99%; Step 3: After the polymer polyvinyl alcohol solution is finished, the heating and stirring of the solution are stopped after the polymerization reaction is completed in the above manner, and the solution is cooled by temperature gradient cooling. The solution is introduced into a constant temperature bath, and the temperature of different parts is adjusted to form a temperature gradient. Specifically, the bottom temperature of the reactor is set to be lower and the top temperature is set to be higher. The PVA solution is gradually cooled and solidified under the action of the temperature gradient. Smaller crystals may be formed at lower temperatures, while larger crystals may be formed at higher temperatures. After the PVA solution is completely solidified and cooled, subsequent purification and treatment are carried out; Step 4: Precipitation and passivation treatment of high molecular weight polyvinyl alcohol solution, add PVA particles and powder into water, add precipitant to induce precipitation of PVA and passivate it with passivator, wait for PVA to precipitate and passivate, use centrifuge to separate PVA precipitate from solution, wash with appropriate amount of solvent to remove residual impurities and precipitant, place the washed PVA precipitate under appropriate conditions for drying to remove excess water.

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