Copolymer for modified pyrrolidone adhesive and preparation method thereof

Abstract

The invention provides a copolymer for a modified pyrrolidone adhesive and a preparation method of the copolymer, and relates to the technical field of preparation of copolymers for adhesives, the copolymer comprises vinyl pyrrolidone, vinyl acetate, a composite initiator, a chain transfer agent and a mixed solvent according to a ratio of (30-60): (15-40): (0.3-0.8): (0.02-0.08): (60-120); the composite initiator is composed of a water-soluble initiator and an oil-soluble initiator according to the mass ratio of 1: (1-2), product performance balance can be achieved by limiting the weight ratio of vinyl pyrrolidone (NVP) to vinyl acetate (VA) to be within the range of (30-60): (15-40), the composite initiator and a mixed solvent system with the specific proportion are adopted, the reaction efficiency can be remarkably improved, and the reaction time is shortened. The problems that an existing copolymer for the modified pyrrolidone adhesive is insufficient in water resistance and low in preparation efficiency are solved, the biocompatibility of the prepared copolymer is improved, and high efficiency of preparation of the modified pyrrolidone adhesive copolymer is achieved.

Description

Technical Field

[0001] This invention relates to the field of copolymer preparation technology for adhesives, and specifically to a modified pyrrolidone adhesive copolymer and its preparation method. Background Technology

[0002] Modified pyrrolidone adhesive copolymers are a class of polymeric materials with N-vinylpyrrolidone (NVP) as one of the main monomers, which are copolymerized with other monomers. They have good bonding properties and film-forming properties and are widely used in the field of adhesives.

[0003] In the prior art, invention patent CN104277178A discloses a method for preparing a copolymer of vinylpyrrolidone and vinyl acetate, which includes at least the following steps: adding a reaction solution comprising N-vinylpyrrolidone, vinyl acetate and ethanol into a polymerization reactor; thoroughly mixing the reaction solution; and adding an azo initiator to the reaction solution to initiate the polymerization reaction of N-vinylpyrrolidone and vinyl acetate. However, this patent uses a one-time addition of monomer initiator, which makes it difficult to control the molecular weight and molecular structure of the product, resulting in high residual monomer content, large temperature fluctuations during the reaction, and difficulty in controlling the ethyl acetate content in the product. Invention patent CN 109384883 A discloses a method for preparing copolyvinylpyrrolidone VA64, including the following steps: (a) mixing an azo initiator, a chain transfer agent, and N-vinylpyrrolidone monomer, and carrying out a polymerization reaction under inert gas protection to obtain polyvinylpyrrolidone, controlling the polymerization reaction temperature at 55-65℃ and the polymerization reaction time at 1-2 hours; (b) adding vinyl acetate monomer and the balance azo initiator to polyvinylpyrrolidone, and carrying out a chain growth reaction under inert gas protection to obtain copolyvinylpyrrolidone VA64. However, this patent uses a method of first preparing polyvinylpyrrolidone and then adding vinyl acetate for polymerization, and the product performance basically fails to meet the requirements, the product structure has poor stability, and there are typical physical encapsulations in the product. Therefore, how to provide a modified pyrrolidone adhesive copolymer with high reaction efficiency and controllable product performance, and its preparation method, is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0004] (a) Technical problems to be solved To address the shortcomings of existing technologies, this invention provides a modified pyrrolidone adhesive copolymer and its preparation method, solving the problems of insufficient water resistance and low preparation efficiency of current modified pyrrolidone adhesive copolymers.

[0005] (II) Technical Solution To achieve the above objectives, the present invention provides the following technical solution: In this invention, a modified pyrrolidone adhesive copolymer comprises vinylpyrrolidone, vinyl acetate, a composite initiator, a chain transfer agent, and a mixed solvent in a ratio of (30-60):(15-40):(0.3-0.8):(0.02-0.08):(60-120); The composite initiator is composed of a water-soluble initiator and an oil-soluble initiator in a mass ratio of 1:(1-2).

[0006] Furthermore, the chain transfer agent is dodecyl mercaptan or n-butyritin.

[0007] Furthermore, the mixed solvent is a mixture of ethanol and water; Ethanol accounts for 60%-80% of the total volume.

[0008] Furthermore, the mass ratio of vinylpyrrolidone to vinyl acetate is 45:25.

[0009] A method for preparing a copolymer for modified pyrrolidone adhesives, specifically comprising the following steps: S1. Add vinylpyrrolidone, vinyl acetate and chain transfer agent to the mixed solvent according to the ratio and stir to mix to obtain a pre-emulsion; S2. Heat the pre-emulsion, then introduce nitrogen and remove oxygen, add the composite initiator in multiple portions, keep stirring and react for a period of time. S3. After the reaction is complete, the product is cooled and precipitated with a mixture of acetone and methanol. The precipitate is filtered, washed with ethanol, and dried under vacuum to obtain the target copolymer.

[0010] Furthermore, in step S1: The stirring rate is 200-300 r / min; Mixing time is 15-20 minutes.

[0011] Furthermore, in step S2: Heat the pre-emulsion to 60-65℃; Nitrogen gas should be introduced over a period of 30 minutes. The stirring rate is 160-220 r / min; The reaction time is 4-5 hours.

[0012] Furthermore, in step S2, when adding the composite initiator: the composite initiator is added in three separate additions, with an interval of 30 minutes between each addition.

[0013] Furthermore, in step S3: The vacuum drying temperature is 60℃; The vacuum drying time is 8 hours.

[0014] Furthermore, in step S3, after cooling the product to below 40°C, it is precipitated using an acetone-methanol mixed precipitant. The volume ratio of the acetone-methanol mixed precipitant is 2:1.

[0015] (III) Beneficial Effects This invention provides a modified pyrrolidone adhesive copolymer and its preparation method. Compared with the prior art, it has the following advantages: By limiting the weight ratio of vinylpyrrolidone (NVP) to vinyl acetate (VA) within the range of (30-60):(15-40), a balance of product performance can be achieved. Furthermore, by using a specific ratio of composite initiator and mixed solvent system, the reaction efficiency can be significantly improved. This solves the problems of insufficient water resistance and low preparation efficiency of the copolymers used in modified pyrrolidone adhesives, enhances the biocompatibility of the prepared copolymers, and achieves high efficiency in the preparation of modified pyrrolidone adhesive copolymers. Detailed Implementation

[0016] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] This application provides a modified pyrrolidone adhesive copolymer and its preparation method, which solves the problems of insufficient water resistance and low preparation efficiency of current modified pyrrolidone adhesive copolymers, and achieves high efficiency in the preparation of modified pyrrolidone adhesive copolymers.

[0018] A modified pyrrolidone adhesive copolymer comprises vinylpyrrolidone, vinyl acetate, a composite initiator, a chain transfer agent, and a mixed solvent in a ratio of (30-60):(15-40):(0.3-0.8):(0.02-0.08):(60-120); The composite initiator is composed of a water-soluble initiator and an oil-soluble initiator in a mass ratio of 1:(1-2); Among them, the water-soluble initiator is ammonium persulfate or potassium persulfate, and the oil-soluble initiator is azobisisobutyronitrile; The copolymer structure is as follows: By limiting the weight ratio of vinylpyrrolidone (NVP) to vinyl acetate (VA) to within the range of (30-60):(15-40), a balance of product performance can be achieved, and by using a specific ratio of composite initiator and mixed solvent system, the reaction efficiency can be significantly improved.

[0019] Specifically, the chain transfer agent is dodecyl mercaptan or n-butanethiol; The mixed solvent is a mixture of ethanol and water, wherein the volume percentage of ethanol is 60%-80%.

[0020] A method for preparing a copolymer for modified pyrrolidone adhesives specifically includes the following steps: S1. Add vinylpyrrolidone, vinyl acetate and chain transfer agent to the mixed solvent according to the ratio, and mix at a stirring rate of 200-300 r / min for 15-20 minutes to obtain a pre-emulsion; S2. Heat the pre-emulsion to 60-65℃, purge with nitrogen for 30 minutes and remove oxygen, then add the composite initiator in three portions, with each addition of the composite initiator 30 minutes apart, maintain a stirring rate of 160-220 r / min and react for 4-5 hours. S3. After the reaction is complete, the product is cooled to below 40°C and precipitated with a mixture of acetone and methanol (volume ratio 2:1). The precipitate is filtered, washed three times with ethanol, and dried under vacuum at 60°C for 8 hours to obtain the target copolymer.

[0021] The preparation process of this invention is simple and controllable. The semi-continuous initiator feeding method reduces the gelation phenomenon, and the molecular weight distribution index of the product is controlled between 1.8 and 2.2, which is suitable for industrial production. Furthermore, the present invention employs a composite initiator system, which can achieve a monomer conversion rate of over 99% at a reaction temperature of 60-65℃, with a residual monomer content of less than 300ppm, significantly improving reaction efficiency and product purity.

[0022] Example 1: Preparation of copolymer for modified pyrrolidone adhesives: At room temperature and 60% humidity, 30 parts of vinylpyrrolidone, 40 parts of vinyl acetate and 0.035 parts of chain transfer agent were added to a mixed solvent and mixed at a stirring rate of 200-300 r / min for 15-20 minutes to obtain a pre-emulsion. Heat the pre-emulsion to 60-65℃, purge with nitrogen for 30 minutes to remove oxygen, then add 0.5 parts of composite initiator in three portions, with each addition of composite initiator 30 minutes apart. Maintain a stirring rate of 160-220 r / min and react for 4-5 hours. The ratio of water-soluble initiator to oil-soluble initiator is 1:1.3. After the reaction was completed, the product was cooled to below 40°C and precipitated with an acetone-methanol mixed precipitant (volume ratio 2:1). The precipitate was filtered, washed three times with ethanol, and dried under vacuum at 60°C for 8 hours to obtain the target copolymer. The water absorption rate of the target copolymer was 21.1%. Example 2: Compared to Example 1, the difference in Example 2 is that the NVP / VA monomer ratio was adjusted to 35:35, and the water absorption rate of the resulting target copolymer was 19.6%. Example 3: Compared to Example 1, the difference in Example 3 is that the NVP / VA monomer ratio was adjusted to 40:30, and the water absorption rate of the resulting target copolymer was 17.2%. Example 4: Compared to Example 1, the difference in Example 4 is that the NVP / VA monomer ratio was adjusted to 45:25, and the water absorption rate of the resulting target copolymer was 15.2%. Example 5: Compared to Example 1, Example 5 differs in that the NVP / VA monomer ratio is adjusted to 50:20, resulting in a water absorption rate of 18.3% for the target copolymer. Example 6: Compared to Example 1, the difference in Example 6 is that the NVP / VA monomer ratio was adjusted to 60:15, and the water absorption rate of the resulting target copolymer was 20.9%. Example 7: Compared to Example 1, the difference in Example 7 is that the polymer (PVP) was prepared by homopolymerization of pure NVP, and the water absorption rate was 25.3%.

[0023] Example 8: Compared to Example 4, the difference in Example 8 is that a composite initiator is added in one step, and the water absorption rate is 24.1%.

[0024] The product performance test results of the embodiments of the present invention are shown in the following table: By adjusting the NVP / VA monomer ratio (30:40 to 60:15) and the composition of the mixed solvent, the hydrophilic-hydrophobic balance of the copolymer can be precisely controlled. When the mass ratio of NVP to VA is 45:25, the water absorption rate of the product is reduced by about 40% compared with pure PVP, while maintaining more than 90% biocompatibility. The CCK-8 assay was used to determine the cytotoxicity of the prepared solution against mesenchymal stem cells (BMSCs). In the experiment, BMSC cells were cultured in 96-well plants. 10 µL of polymer aqueous solutions prepared with different NVP / VA monomer ratios were cultured with the cells for 24 hours, followed by 10 µL of CCK-8 solution. The cells were then cultured together at 37°C (5% CO2) for another 2 hours. Cells cultured without any extract were used as a control group. Finally, the optical density (OD) at 450 nm was measured using a microplate reader, and cell viability was calculated according to formula (1). Wherein: ODc and ODs are the optical density (OD) values ​​of the blank control and the sample, respectively; Biocompatibility is reflected in the results corresponding to cell survival rate. The higher the cell survival rate, the better the compatibility of the prepared copolymer.

[0025] In summary, this application develops a semi-continuous feeding process to control molecular weight distribution, resulting in modified products with excellent bonding properties. In practical applications, the copolymer prepared by the method for preparing modified pyrrolidone adhesive copolymers is used as part of the adhesive, enabling the wood bonding strength to reach 1.8 MPa, which is 15% higher than that of acrylate modified products, and the VOC content is less than 50 g / L, meeting environmental protection requirements.

[0026] In summary, compared with existing technologies, it has the following beneficial effects: 1. By limiting the weight ratio of vinylpyrrolidone (NVP) to vinyl acetate (VA) within the range of (30-60):(15-40), the product performance can be balanced. Furthermore, by using a specific ratio of composite initiator and mixed solvent system, the reaction efficiency can be significantly improved. This solves the problems of insufficient water resistance and low preparation efficiency of the copolymers used in modified pyrrolidone adhesives, and achieves high efficiency in the preparation of modified pyrrolidone adhesive copolymers.

[0027] 2. The preparation process of this invention is simple and controllable. The semi-continuous initiator feeding method reduces the gelation phenomenon, and the molecular weight distribution index of the product is controlled between 1.8 and 2.2, which is suitable for industrial production.

[0028] 3. By adjusting the NVP / VA monomer ratio (30:40 to 60:15) and the composition of the mixed solvent, the hydrophilic-hydrophobic balance of the copolymer can be precisely controlled. When the mass ratio of NVP to VA is 45:25, the water absorption rate of the product is reduced by about 40% compared with pure PVP, while maintaining more than 90% biocompatibility.

[0029] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0030] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A copolymer for modified pyrrolidone adhesives, characterized in that, The compound initiator is composed of water-soluble initiator and oil-soluble initiator in a mass ratio of 1: (1-2). The chain transfer agent is dodecanethiol or n-butyl mercaptan.

2. A copolymer for use in a modified pyrrolidone adhesive according to claim 1, characterized in that, The mixed solvent is a mixture of ethanol and water.

3. The copolymer for a modified pyrrolidone adhesive according to claim 1, wherein The volume ratio of ethanol is 60%-80%. The mass ratio of the vinyl pyrrolidone and vinyl acetate is 45:

25.

4. The copolymer for modified pyrrolidone adhesives as described in claim 1 and its preparation method, characterized in that, Specifically comprising the following steps:

5. A method for producing a copolymer for a modified pyrrolidone adhesive, for producing the copolymer for a modified pyrrolidone adhesive according to any one of claims 1 to 4, characterized by, S1, according to the proportion, the vinyl pyrrolidone, vinyl acetate and chain transfer agent are added to the mixed solvent and stirred to obtain a pre-emulsion; S2, the pre-emulsion is heated, then nitrogen is introduced and oxygen is removed, and then the compound initiator is added in multiple times, stirring is maintained and reaction is carried out for a period of time; S3, after the reaction is completed, the product is cooled and precipitated with a mixture of acetone-methanol precipitant, the obtained precipitate is filtered, washed with ethanol, and vacuum dried to obtain the target copolymer. In step S1:

6. The method of claim 5, wherein the copolymer is prepared by the steps of: (a) dissolving the monomers in a solvent; (b) adding a free radical initiator to the solution; (c) polymerizing the monomers; and (d) recovering the copolymer. The stirring rate is 200-300 r / min; The mixing time is 15-20 minutes. In step S2:

7. The method of claim 5, wherein the copolymer is prepared by the steps of: (a) dissolving the monomers in a solvent; (b) adding a free radical initiator to the solution; (c) polymerizing the monomers; and (d) recovering the copolymer. The temperature of the pre-emulsion is heated to 60-65℃; The nitrogen introduction time is 30 minutes; The stirring rate is 160-220 r / min; The reaction time is 4-5 hours. In step S2, when the compound initiator is added: the compound initiator is added in three times, and the interval time of each addition of the compound initiator is 30 minutes.

8. The method of claim 5, wherein the copolymer is prepared by the steps of: (a) dissolving the monomers in a solvent; (b) adding a free radical initiator to the solution; (c) polymerizing the monomers; and (d) recovering the copolymer. In step S3:

9. The method of claim 5, wherein the copolymer is prepared by the steps of: (a) dissolving the monomers in a solvent; (b) adding a free radical initiator to the solution; (c) polymerizing the monomers; and (d) recovering the copolymer. The vacuum drying temperature is 60℃; The vacuum drying time is 8 hours. In step S3, after the temperature of the product is cooled to below 40℃, the product is precipitated with a mixture of acetone-methanol precipitant; 10. The method of claim 5, wherein the copolymer is prepared by the steps of: (a) dissolving the monomers in a solvent; (b) adding a free radical initiator to the solution; (c) polymerizing the monomers; and (d) recovering the copolymer. The volume ratio of the acetone-methanol mixed precipitant is 2:

1. ​

Images