CN108623736B - Self-crosslinking polyvinyl acetate film-forming agent and preparation method and application thereof - Google Patents
Self-crosslinking polyvinyl acetate film-forming agent and preparation method and application thereof Download PDFInfo
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- C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
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Abstract
The invention provides a self-crosslinking polyvinyl acetate film-forming agent, which comprises the preparation components of vinyl acetate, deionized water, modified polyvinyl alcohol, an emulsifier, a reactive emulsifier, a crosslinking monomer, an initiator and a pH value regulator, wherein the crosslinking monomer is an amide compound. The film forming agent prepared by the mutual matching of the components has the characteristics of strong precursor bundling property, excellent high-temperature performance, high stiffness, good self-crosslinking property, good solvent resistance and the like. The invention also provides a preparation method and application of the self-crosslinking polyvinyl acetate film-forming agent.
Description
Technical Field
The invention relates to the field of film forming agents, in particular to a self-crosslinking polyvinyl acetate film forming agent, a preparation method and application thereof.
Background
The film forming agent is the main component in the impregnating compound used in the high-speed drawing process of the glass fiber, can bond hundreds of glass fibers, forms a layer of protective film on the surface of the fibers, endows the glass fibers with good technological properties such as wettability, stiffness, banding property, short cutting property, dispersibility and the like, and protects the glass fibers from being damaged in the subsequent processing procedure, thereby meeting the requirements of various forming technological properties of glass fiber products. Therefore, the performance of the film forming agent directly influences the use effect of the impregnating compound.
At present, the forming process of the reinforced composite material has higher requirements on the performance of glass fibers coated with the sizing agent, and for example, 3-12 mm chopped yarns used in the forming process of SMC or BMC are taken as examples, firstly, the glass fiber strands are required to keep good bundling property after being chopped, no fiber splitting is performed, the number of wool yarn wool lumps is small, the end faces are neat, and the flowability is good; secondly, the protofilament needs to have certain stiffness, so that the cutting is facilitated, and meanwhile, the cut chopped yarn has high stiffness and good fluidity; thirdly, the chopped yarns are required to have the characteristic of low dissolution degree in styrene, the soaking time is 1.5-2.5 min, and the chopped yarns are not split within 20s after being thrown into the styrene.
The polyvinyl acetate emulsion is a common film forming agent, the film forming agent is a high molecular product prepared by emulsion polymerization, the molecular weight is larger, the film toughness is good, the protection effect on glass fiber is good, good cutting performance and stiffness can be endowed to protofilaments, and the polyvinyl acetate emulsion has the advantages of relatively lower price, relatively better bonding performance, excellent bundling performance, easy cutting and the like.
However, the existing polyvinyl acetate film-forming agent still has the following disadvantages: firstly, the anionic polyvinyl acetate emulsion is not well matched with a cationic lubricant and an antistatic agent in a glass fiber impregnating compound, so that the stability of the impregnating compound is seriously influenced, and the quality of yarn is influenced; secondly, the non-ionic polyvinyl acetate emulsion contains polyvinyl alcohol protective colloid, and the prepared glass fiber yarn or felt is slower to be soaked in unsaturated polyester, thereby influencing the production speed and the product quality of the glass fiber reinforced plastic product.
Disclosure of Invention
The present invention is directed to solving the problems described above. The invention aims to provide a self-crosslinking polyvinyl acetate film-forming agent and a preparation method thereof, the self-crosslinking polyvinyl acetate film-forming agent adopts modified polyvinyl alcohol as a protective colloid, introduces a reactive emulsifier to endow a polymer with self-emulsifying capacity, and simultaneously introduces a crosslinking monomer to form a three-dimensional network structure in the film forming process of the original linear structure, improves solvent resistance, and has the characteristics of strong precursor bundling property, excellent high-temperature performance, high soaking speed and the like.
The invention provides a self-crosslinking polyvinyl acetate film-forming agent, which comprises the following components in percentage by mass:
wherein the modified polyvinyl alcohol is polyvinyl acetal; the reactive emulsifier is polyoxyethylene nonyl ether or succinic acid-glycidyl methacrylate condensate.
Wherein, the modified polyvinyl alcohol is prepared by the acetal reaction of two polyvinyl alcohols with the trade marks of BP-20, BF-17, BP-17 and BF-20 and formaldehyde or butyraldehyde; the reactive emulsifier is a vinyl-containing emulsifier.
Wherein the mass ratio of the reactive emulsifier to the vinyl acetate monomer is 1: 9-2: 3.
Wherein the crosslinking monomer is one or more of N-methylol acrylamide, sulfomethylated acrylamide and methacrylamide.
Wherein the emulsifier is one or more of nonylphenol polyoxyethylene ether and fatty alcohol polyoxyethylene ether with the brands of NP-10 and NP-20; the initiator is ammonium persulfate or potassium persulfate; the pH value regulator is sodium bicarbonate.
The preparation components of the self-crosslinking polyvinyl acetate film-forming agent comprise the following components in percentage by mass:
the modified polyvinyl alcohol is prepared by two polyvinyl alcohols with the trade marks of BP-20, BF-17, BP-17 and BF-20 and formaldehyde through an acetal reaction; the crosslinking monomer is N-methylol acrylamide.
The invention also provides a preparation method of the self-crosslinking polyvinyl acetate film-forming agent, wherein the modified polyvinyl alcohol is prepared by the acetal reaction of two polyvinyl alcohols and aldehyde, and the preparation method comprises the following steps:
preparation of 1S modified polyvinyl alcohol: weighing two kinds of polyvinyl alcohol and aldehyde according to the mass of modified polyvinyl alcohol required by preparing a film-forming agent, preparing a proper amount of deionized water, hydrochloric acid, urea and sodium bicarbonate, and carrying out condensation reaction on the two kinds of polyvinyl alcohol and aldehyde through a high-molecular functional group under an acidic condition to generate a intramolecular acetal compound so as to prepare modified polyvinyl alcohol emulsion;
preparation of 2S seed emulsion: controlling the temperature of the modified polyvinyl alcohol emulsion obtained in the step 1S to be 50-60 ℃, adding an emulsifier and a pH value regulator, and stirring for 30-40 minutes; dissolving an initiator in deionized water with the mass of 28-32 times that of the initiator to prepare an initiator solution for later use, and uniformly stirring vinyl acetate and a reactive emulsifier to prepare a mixed monomer for later use; after the pH value regulator is completely dissolved, adding an initiator solution with the mass of 20-30% of the total amount, stirring for 30-40 minutes, heating to 68-72 ℃, dropwise adding a mixed monomer with the total amount of 15-20%, and reacting for 30-50 minutes to obtain a seed emulsion;
3S preparation of film-forming agent: dropwise adding the residual mixed monomer and the initiator solution in the step 2 into the prepared seed emulsion, uniformly stirring the crosslinking monomer and the residual mixed monomer when the mixed monomer has a residual preset amount, and continuously dropwise adding, wherein the residual initiator solution is added at one time after the dropwise adding of the mixture of the crosslinking monomer and the residual monomer is finished; heating to 80-85 ℃, preserving heat for at least 1.5 hours, cooling to below 40 ℃, filtering and discharging to obtain the film-forming agent.
Wherein the residual preset amount of the mixed monomers in the step 3S is 10-30% of the total amount of the mixed monomers.
The invention also provides the application of the self-crosslinking polyvinyl acetate film-forming agent in the production of impregnating compound for sheet molding compound, bulk molding compound or saturated polyester reinforced material.
The self-crosslinking polyvinyl acetate film-forming agent provided by the invention has the main innovation points that: firstly, the modified polyvinyl alcohol is used as a protective colloid and is matched with other components, so that the soaking speed of the glass fiber yarns in the unsaturated polyester resin is improved; secondly, a reactive emulsifier is introduced, so that the emulsifying effect is achieved on one hand, and the reactive emulsifier can be copolymerized with a vinyl acetate monomer on the other hand, so that the self-emulsifying capacity of the vinyl acetate polymer is endowed; thirdly, by introducing the crosslinking monomer, the original linear structure forms a three-dimensional network structure in the film forming process, and the solvent resistance is improved. The film forming agent which has the characteristics of strong precursor bundling property, excellent high-temperature performance, high stiffness, good self-crosslinking property, good solvent resistance and the like is prepared by the mutual matching of substances such as modified polyvinyl alcohol, an emulsifier, a reactive emulsifier, a crosslinking monomer, an initiator, a pH value regulator and the like.
Specifically, the preparation component of the self-crosslinking polyvinyl acetate film-forming agent comprises vinyl acetate, deionized water, modified polyvinyl alcohol, an emulsifier, a reactive emulsifier, a crosslinking monomer, an initiator and a pH value regulator, wherein the crosslinking monomer is an amide compound.
In the preparation components of the self-crosslinking polyvinyl acetate film-forming agent, the functions and contents of the components are described as follows:
the modified polyvinyl alcohol is used as a protective colloid in the invention, and the main function of the modified polyvinyl alcohol is to form a protective layer on the surface of the polymer to prevent the polymer from merging and coagulating, compared with polyvinyl alcohol, the problem of slow permeation speed of glass fiber yarns or felts in unsaturated polyester can be greatly improved, wherein the mass percentage of the modified polyvinyl alcohol is 0.5-2%, and preferably 0.8-1.8%. Further, the modified polyvinyl alcohol is polyvinyl acetal substances, preferably prepared by acetalization reaction of two polyvinyl alcohols of BP-20, BF-17, BP-17 and BF-20 and aldehyde substances, wherein the combination of the two polyvinyl alcohols is preferably the polyvinyl alcohol of BP-20 and BF-17 or the polyvinyl alcohol of BP-17 and BF-20. The aldehyde substance is preferably formaldehyde or butyraldehyde, and most preferably formaldehyde. The molecular acetal compound prepared by using the polyvinyl alcohol combination with the brand numbers of BP-20 and BF-17, the polyvinyl alcohol combination with the brand numbers of BP-17 and BF-20 and formaldehyde is particularly suitable for preparing the film forming agent, so that the soaking speed of the glass fiber yarns in unsaturated resin is optimal, and the production speed and the product quality of glass fiber reinforced plastic products are effectively improved.
The emulsifier has the main function of promoting the conversion of oil-water two phases into stable emulsion, and structurally, the emulsifier simultaneously has hydrophilic groups and lipophilic groups. Wherein the content of the emulsifier is 1-2.5%, preferably 1-2%. The content of the reactive emulsifier is 3-20%, preferably 5-15%.
Further, the emulsifier is one or more of nonylphenol polyoxyethylene ether NP-10, NP-20 and fatty alcohol polyoxyethylene ether. The reactive emulsifier is preferably vinyl-containing emulsifier, and copolymerization reaction is carried out between unsaturated bond of the reactive emulsifier and vinyl acetate. More preferably, the reactive emulsifier is polyoxyethylene nonylphenol ether or succinic acid-glycidyl methacrylate condensate. Through a great deal of research, the inventor finds that when the mass ratio of the reactive emulsifier to the vinyl acetate monomer is 1: 9-2: 3, the film forming agent precursor has stronger bundling property and excellent high-temperature performance, and more preferably, the mass ratio of the reactive emulsifier to the vinyl acetate monomer is 3: 17.
As another important point of the invention, the reaction system of the invention introduces the crosslinking monomer, so that the film forming agent forms a three-dimensional network structure from the original linear structure in the generation process, has self-crosslinking property and improves the solvent resistance. The crosslinking monomer used in the present invention is an amide compound, and the content thereof is 0.1 to 2%, preferably 0.1 to 1.5%. Preferably, the crosslinking monomer is one or more of N-methylolacrylamide, sulfomethylated acrylamide and methacrylamide, most preferably N-methylolacrylamide.
The dosage of the initiator can directly influence the polymerization rate of vinyl acetate and the polymerization degree of the polymer, and the mass percentage of the initiator is controlled to be 0.1-0.25%. Furthermore, the initiator adopts ammonium persulfate or potassium persulfate, and the prepared film-forming agent has good performance.
In the invention, the pH value regulator adopts sodium bicarbonate namely NaHCO3The mass percentage of the inorganic filler is 0.05-0.2%, preferably 0.05-0.15%. The mass percentage of the vinyl acetate is 30-45%, preferably 35-45%.
The deionized water is mainly used as a solvent to disperse the components serving as the raw materials, and the mass percent of the deionized water is 40-50%, preferably 45-50%.
As a preferable example of the invention, the preparation component of the self-crosslinking polyvinyl acetate film former comprises the following components, the crosslinking monomer is an amide compound, wherein the content of each component is expressed by mass percent as follows:
the modified polyvinyl alcohol is polyvinyl acetal, and the reactive emulsifier is a vinyl-containing emulsifier.
As another preferable example of the invention, the preparation component of the self-crosslinking polyvinyl acetate film former comprises the following components, the crosslinking monomer is an amide compound, and the content of each component is expressed by mass percent as follows:
the modified polyvinyl alcohol is prepared by carrying out acetal reaction on polyvinyl alcohol with the brands of BP-20 and BF-17 and formaldehyde; the crosslinking monomer is N-methylol acrylamide.
According to another aspect of the present invention, there is provided a method for preparing the self-crosslinking polyvinyl acetate film-forming agent, comprising the following steps:
preparation of 1S modified polyvinyl alcohol: weighing two kinds of polyvinyl alcohol and aldehyde according to the mass of modified polyvinyl alcohol required by preparing a film-forming agent, preparing a proper amount of deionized water, hydrochloric acid, urea and sodium bicarbonate, and carrying out condensation reaction on the two kinds of polyvinyl alcohol and aldehyde through a high-molecular functional group under an acidic condition to generate a intramolecular acetal compound so as to prepare modified polyvinyl alcohol emulsion;
preparation of 2S seed emulsion: controlling the temperature of the modified polyvinyl alcohol emulsion obtained in the step 1S to be 50-60 ℃, adding an emulsifier and a pH value regulator, and stirring for 30-40 minutes; dissolving an initiator in deionized water with the mass of 28-32 times that of the initiator to prepare an initiator solution for later use, and uniformly stirring vinyl acetate and a reactive emulsifier to prepare a mixed monomer for later use; after the pH value regulator is completely dissolved, adding an initiator solution with the mass of 20-30% of the total amount, stirring for 30-40 minutes, heating to 68-72 ℃, dropwise adding a mixed monomer with the total amount of 15-20%, and reacting for 30-50 minutes to obtain a seed emulsion;
3S preparation of film-forming agent: dropwise adding the residual mixed monomer and the initiator solution in the step 2 into the prepared seed emulsion, uniformly stirring the crosslinking monomer and the residual mixed monomer when the mixed monomer has a residual preset amount, and continuously dropwise adding, wherein the residual initiator solution is added at one time after the dropwise adding of the mixture of the crosslinking monomer and the residual monomer is finished; heating to 80-85 ℃, preserving heat for at least 1.5 hours, cooling to below 40 ℃, filtering and discharging to obtain the film-forming agent.
Wherein, the modified polyvinyl alcohol is prepared by the acetalization reaction of two polyvinyl alcohols and aldehyde.
The preparation method is carried out in sequence according to the sequence of 1S-3S, wherein the modified polyvinyl alcohol is used as a raw material to participate in the preparation of the film-forming agent, and the content of the components such as polyvinyl alcohol, aldehyde, deionized water, hydrochloric acid, urea, sodium bicarbonate and the like for preparing the modified polyvinyl alcohol is not included in the component relationship for preparing the film-forming agent provided by the invention. Therefore, the modified polyvinyl alcohol can participate in the reaction of the step 2S in the form of pure components, and then is dissolved by using deionized water; the modified polyvinyl alcohol emulsion prepared in the step 1S can also be directly used as a reaction raw material to participate in the reaction in the step 2S, so that the contents of the modified polyvinyl alcohol in the modified polyvinyl alcohol emulsion and the deionized water used as a solvent need to meet the component relationship for preparing the film-forming agent.
From the step 2S, the vinyl acetate and the reactive emulsifier are uniformly stirred to prepare a mixed monomer, the vinyl acetate and the reactive emulsifier in the mixed monomer are copolymerized, and the seed emulsion is prepared by reacting the mixed monomer, so that not only is the reaction system more stable, but also the vinyl acetate polymer obtained by the reaction has self-emulsifying capacity.
In the step 3S, the mixed monomer and the initiator solution which are left in the step 2S are dropwise added into the prepared seed emulsion, when the mixed monomer has a predetermined amount, the crosslinking monomer and the rest of the mixed monomer are uniformly stirred and then are continuously dropwise added, and when the dropwise addition of the mixture of the crosslinking monomer and the rest of the monomers is finished, the rest of the initiator solution is added at one time; heating to 80-85 ℃, preserving heat for at least 1.5 hours, cooling to below 40 ℃, filtering and discharging to obtain the film-forming agent.
Specifically, 1-4% of initiator solution by mass is dripped into the initiator solution every 10-30 minutes, and the mixed monomer is continuously dripped at a certain speed. When the mixed monomer has a predetermined amount, the mixed monomer and the crosslinking monomer are mixed and then dropwise added, and after all the monomers are dropwise added, the rest of the initiator solution is added at one time to finally prepare the film-forming agent, wherein the film-forming agent is emulsion.
Further, when the residual amount of the mixed monomer in the step 3S is 10-30% of the total amount, the mixed monomer and the crosslinking monomer are mixed, so that in the process of forming the film forming agent, a three-dimensional net structure is formed by a linear structure of an original system, and the solvent resistance is improved. Also, the remaining amount of the mixed monomers is preferably 25% of the total amount.
It should be noted that the modified polyvinyl alcohol is used as a reaction raw material to participate in the preparation of the film-forming agent, and the dosage of the modified polyvinyl alcohol meets the proportional relationship of the invention. The amounts of the components used in the above preparation process need to satisfy the proportional relationship described in the present invention, and those skilled in the art can make adaptive adjustments based on the above preparation method according to actual situations.
According to a third aspect of the present invention, there is provided the use of the self-crosslinking polyvinyl acetate film former in the production of a sizing for sheet molding compounds, bulk molding compounds or saturated polyester reinforcements.
Compared with the prior art, the film forming agent which has the characteristics of strong precursor bundling property, excellent high-temperature performance, high stiffness, good self-crosslinking property, good solvent resistance and the like is prepared by the mutual matching of the modified polyvinyl alcohol, the emulsifier, the reactive emulsifier, the crosslinking monomer, the initiator, the pH value regulator and the like.
The beneficial effects are as follows:
firstly, the invention uses the modified polyvinyl alcohol as the protective colloid and is matched with other components, thereby effectively improving the soaking speed of the glass fiber yarn or felt which uses the film forming agent of the invention and resin.
Secondly, the reactive emulsifier is introduced, so that the emulsification is achieved, and the copolymerization of the reactive emulsifier and a vinyl acetate monomer is achieved, so that the self-emulsification capability of the vinyl acetate polymer is endowed, the reaction of the film forming agent and the stability of a system are facilitated, the precursor bundling property of the film forming agent is effectively improved, and the high-temperature performance is excellent.
Thirdly, the invention leads the original linear structure to form a three-dimensional network structure in the film forming process by introducing the crosslinking monomer, has self-crosslinking property and improves the solvent resistance of the film forming agent.
The selection of the preparation components and the content of the self-crosslinking polyvinyl acetate film-forming agent and the beneficial effects of the preparation method of the self-crosslinking polyvinyl acetate film-forming agent are illustrated by specific experimental data given by the examples.
Drawings
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention, in which like reference numerals are used to designate like elements, and the drawings in the following description are some, but not all embodiments of the invention, and will enable one of ordinary skill in the art to make and use the invention.
FIG. 1 shows a flow chart for the preparation of a self-crosslinking polyvinyl acetate film former in accordance with the present invention;
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention. It should be noted that the embodiments and features of the embodiments in the present application may be arbitrarily combined with each other without conflict.
Example 1
Weighing the components according to the mass percentage, wherein the modified polyvinyl alcohol is prepared by the acetal reaction of two polyvinyl alcohols with the brands of BP-20 and BF-17 and formaldehyde, and the self-crosslinking polyvinyl acetate film-forming agent is prepared by the following steps:
preparation of 1S modified polyvinyl alcohol: weighing two polyvinyl alcohols and aldehyde according to the mass of modified polyvinyl alcohol required by preparing a film-forming agent, preparing a proper amount of deionized water, hydrochloric acid, urea and sodium bicarbonate, specifically adding deionized water and polyvinyl alcohol into a reaction vessel containing a stirrer, a feeder, a reflux condenser tube and a thermometer, stirring, heating to 90 ℃ to completely dissolve the polyvinyl alcohol, cooling to 80 ℃, adding hydrochloric acid to adjust the pH value to 1-2, beginning to dropwise add formaldehyde, controlling the dropwise addition of formaldehyde within 20 minutes, keeping the temperature for 45 minutes, adding urea to perform an acetal reaction, and finally adjusting the pH value to 7 by using sodium bicarbonate to prepare a modified polyvinyl alcohol emulsion;
preparation of 2S seed emulsion: controlling the temperature of the modified polyvinyl alcohol emulsion obtained in the step 1S to be 55 ℃, adding 4g of emulsifier A, 3g of emulsifier B, fatty alcohol polyoxyethylene ether and 0.6g of sodium bicarbonate, and stirring for 35 minutes; 1g of initiator ammonium persulfate is added into 30g of deionized water to be dissolved, 170g of vinyl acetate and 30g of reactive emulsifier with the mark of AE-320 are stirred uniformly to prepare a mixed monomer, 6.4g of initiator solution is added after sodium bicarbonate is completely dissolved, stirring is carried out for 30 minutes, the temperature is raised to 70 ℃, 30g of mixed monomer is added dropwise, the dropping is finished within 10 minutes, and the reaction is carried out for 50 minutes until the reflux is not carried out again to prepare seed emulsion;
3S preparation of film-forming agent: dropwise adding the remaining mixed monomer in the step 2S into the prepared seed emulsion, dropwise adding 0.6g of initiator solution every 15 minutes in the dropwise adding process, after the mixed monomer is dropwise added for 3 hours, stirring the crosslinking monomer and the remaining mixed monomer uniformly and continuously dropwise adding when one fourth of the total amount of the mixed monomer remains, and after the dropwise adding of the mixture of the crosslinking monomer and the remaining monomer is finished, adding the remaining initiator solution at one time; stirring for 15 min, heating to 80 deg.C, holding for 1.5 hr, cooling to below 40 deg.C, filtering, and discharging to obtain film-forming agent.
The solid content of the finally prepared self-crosslinking polyvinyl acetate film-forming agent is 50.9%, the particle size is 1.004 mu m, the pH value is 4.5, and the acetone dissolution rate is 8%.
Examples 2 to 7 referring to the preparation process of example 1, the amounts of the components should satisfy the proportional relationship of the present invention, and those skilled in the art can make adaptive adjustments based on the above preparation method according to actual situations. The specific example conditions are shown in table 1:
TABLE 1 tabulation of specific examples of self-crosslinking polyvinyl acetate film formers
| Item | Example 1 | Example 2 | Example 3 | Example 4 | Example 5 | Example 6 | Example 7 |
| Vinyl acetate/g | 170 | 180 | 160 | 150 | 170 | 170 | 170 |
| Deionized water/g | 210 | 210 | 210 | 210 | 210 | 210 | 210 |
| Modified polyvinyl alcohol/g | 5 | 7 | 6 | 3.5 | 5 | 5 | 5 |
| Emulsifier A/g | 4 | 4 | 4 | 4 | 4 | 4 | 4 |
| Emulsifier B/g | 3 | 3 | 3 | 3 | 3 | 3 | 3 |
| Reactive emulsifier/g | 30 | 20 | 40 | 50 | 30 | 30 | 30 |
| Crosslinking monomer/g | 1.5 | 2 | 1.5 | 1.5 | 1.5 | 1.5 | 1.5 |
| Initiator/g | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
| pH value regulator/g | 0.6 | 0.6 | 0.6 | 0.6 | 0.6 | 0.6 | 0.6 |
| Solid content (%) | 50.9 | 51.0 | 50.8 | 51.4 | 51.6 | 51.2 | 50.9 |
| Particle size (. mu.m) | 1.004 | 0.986 | 1.120 | 1.058 | 0.967 | 0.985 | 1.032 |
| pH value | 4.50 | 4.35 | 4.40 | 4.35 | 4.36 | 4.40 | 4.55 |
| Acetone dissolution rate/%) | 8 | 5 | 7 | 6 | 10 | 8 | 9 |
Wherein, emulsifier A is nonylphenol polyoxyethylene ether, emulsifier B is fatty alcohol polyoxyethylene ether, initiator is ammonium persulfate, pH value regulator is sodium bicarbonate, crosslinking monomer is N-methylolacrylamide, polyvinyl alcohol and aldehyde used for modifying polyvinyl alcohol, and substances used for reactive emulsifier are shown in Table 2:
TABLE 2 materials used for polyvinyl alcohol and reactive emulsifier or Components for their preparation
Comparative example
In order to further illustrate the beneficial effects of the invention, the currently more commonly used self-crosslinking polyvinyl acetate film-forming agent is selected as a comparative example, and the brand number of the film-forming agent is TH-730.
Test example
The above examples and comparative examples were prepared as glass fiber sizing agents, and the performance of glass fibers and their reinforcing materials was tested. Wherein the mass percent of the film forming agent in the prepared impregnating compound is 15%, the impregnating compound is used for coating glass fibers, the produced glass fibers are cut into 5-8 mm chopped yarns, the performance detection result is shown in table 3, and the soaking speed is characterized by the soaking time under the same condition:
TABLE 3 different glass fiber yarns and Performance test results
| Testing performance | Example 1 | Example 2 | Example 3 | Example 4 | Example 5 | Example 6 | Example 7 | Comparative example |
| Short cut rate/% of | 0.5 | 1.2 | 0.7 | 0.8 | 0.6 | 0.4 | 0.5 | 2.1 |
| Amount of hairiness/%) | 0.021 | 0.095 | 0.062 | 0.085 | 0.052 | 0.035 | 0.074 | 0.155 |
| Styrene penetration Rate/s | 95 | 110 | 102 | 93 | 98 | 92 | 105 | 160 |
From the above test examples, it can be seen that the short-cut splitting ratios and the hairiness amounts of the examples 1 to 7 are much lower than those of the comparative examples, specifically, the average short-cut difference ratios of the examples 1 to 7 are 0.67%, which is reduced by 68.1% compared with 2.1% of the comparative example; the average hairiness amount is 0.06%, which is reduced by 61.3% compared with 0.155% of the comparison ratio. The film forming agent provided by the invention has excellent precursor convergence, no fiber opening and less wool yarn and wool lumps. The average penetration rate of styrene in examples 1 to 7 was 99.3s, while the penetration rate of comparative example was 160s, and the present invention was significantly improved in the penetration rate and excellent in the performance as compared with the comparative example.
In summary, the invention has the following beneficial effects:
firstly, the invention uses the modified polyvinyl alcohol as the protective colloid and is matched with other components, thereby effectively improving the soaking speed of the glass fiber yarn or felt which uses the film forming agent of the invention and resin.
Secondly, the reactive emulsifier is introduced, so that the emulsification is achieved, and the copolymerization of the reactive emulsifier and a vinyl acetate monomer is achieved, so that the self-emulsification capability of the vinyl acetate polymer is endowed, the reaction of the film forming agent and the stability of a system are facilitated, the precursor bundling property of the film forming agent is effectively improved, and the high-temperature performance is excellent.
Thirdly, the invention leads the original linear structure to form a three-dimensional network structure in the film forming process by introducing the crosslinking monomer, has self-crosslinking property and improves the solvent resistance of the film forming agent.
The invention also provides the application of the self-crosslinking polyvinyl acetate film-forming agent in the production of impregnating compound for sheet molding compound, bulk molding compound or saturated polyester reinforced material.
Finally, it should be noted that: in this document, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
The above examples are only for illustrating the technical solutions of the present invention, and are not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (9)
1. The self-crosslinking polyvinyl acetate film-forming agent is characterized in that the preparation component of the self-crosslinking polyvinyl acetate film-forming agent comprises the following components, wherein a crosslinking monomer is an amide compound, and the content of each component is represented by mass percent as follows:
the modified polyvinyl alcohol is polyvinyl acetal, and the reactive emulsifier is an emulsifier containing unsaturated bonds or vinyl.
2. The self-crosslinking polyvinyl acetate film-forming agent according to claim 1, wherein the modified polyvinyl alcohol is prepared by acetalization of two polyvinyl alcohols of grades BP-20, BF-17, BP-17 and BF-20 with formaldehyde or butyraldehyde; the reactive emulsifier is a vinyl-containing emulsifier.
3. The self-crosslinking polyvinyl acetate film-forming agent according to claim 1, wherein the mass ratio of the reactive emulsifier to the vinyl acetate monomer is 1: 9-2: 3.
4. The self-crosslinking polyvinyl acetate film-forming agent according to any one of claims 1 to 3, wherein the crosslinking monomer is one or more of N-methylol acrylamide, sulfomethylated acrylamide and methacrylamide.
5. The self-crosslinking polyvinyl acetate film-forming agent according to any one of claims 1 to 3,
the emulsifier is one or more of nonylphenol polyoxyethylene ether and fatty alcohol polyoxyethylene ether with the brands of NP-10 and NP-20;
the initiator is ammonium persulfate or potassium persulfate;
the pH value regulator is sodium bicarbonate.
6. The self-crosslinking polyvinyl acetate film-forming agent according to claim 1, wherein the content of each component is expressed by mass percent as follows:
the modified polyvinyl alcohol is prepared by two polyvinyl alcohols with the trade marks of BP-20, BF-17, BP-17 and BF-20 and formaldehyde through an acetal reaction; the crosslinking monomer is N-methylol acrylamide.
7. The preparation method of the self-crosslinking polyvinyl acetate film-forming agent as claimed in any one of claims 1 to 6, wherein the modified polyvinyl alcohol is prepared by acetalization reaction of two polyvinyl alcohols and aldehyde, and the preparation method comprises the following steps:
preparation of 1S modified polyvinyl alcohol: weighing two kinds of polyvinyl alcohol and aldehyde according to the mass of modified polyvinyl alcohol required by preparing a film-forming agent, preparing a proper amount of deionized water, hydrochloric acid, urea and sodium bicarbonate, and carrying out condensation reaction on the two kinds of polyvinyl alcohol and aldehyde through a high-molecular functional group under an acidic condition to generate a intramolecular acetal compound so as to prepare modified polyvinyl alcohol emulsion;
preparation of 2S seed emulsion: controlling the temperature of the modified polyvinyl alcohol emulsion obtained in the step 1S to be 50-60 ℃, adding an emulsifier and a pH value regulator, and stirring for 30-40 minutes; dissolving an initiator in deionized water with the mass of 28-32 times that of the initiator to prepare an initiator solution for later use, and uniformly stirring vinyl acetate and a reactive emulsifier to prepare a mixed monomer for later use; after the pH value regulator is completely dissolved, adding an initiator solution with the mass of 20-30% of the total amount, stirring for 30-40 minutes, heating to 68-72 ℃, dropwise adding a mixed monomer with the total amount of 15-20%, and reacting for 30-50 minutes to obtain a seed emulsion;
3S preparation of film-forming agent: dropwise adding the residual mixed monomer and the initiator solution in the step 2 into the prepared seed emulsion, uniformly stirring the crosslinking monomer and the residual mixed monomer when the mixed monomer has a residual preset amount, and continuously dropwise adding, wherein the residual initiator solution is added at one time after the dropwise adding of the mixture of the crosslinking monomer and the residual monomer is finished; heating to 80-85 ℃, preserving heat for at least 1.5 hours, cooling to below 40 ℃, filtering and discharging to obtain the film-forming agent.
8. The method for preparing a self-crosslinking polyvinyl acetate film-forming agent according to claim 7, wherein the predetermined amount of the mixed monomers remaining in the step 3S is 10 to 30% of the total amount of the mixed monomers.
9. Use of the self-crosslinking polyvinyl acetate film-forming agent as defined in any one of claims 1 to 6 in the production of a sizing agent for sheet molding compounds, bulk molding compounds or saturated polyester reinforcements.
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| CN112574735B (en) * | 2020-12-14 | 2022-03-11 | 西南石油大学 | Preparation method of thickening agent for temperature-resistant fracturing fluid with double-network structure |
| CN113831050B (en) * | 2021-09-13 | 2022-07-26 | 中建商品混凝土有限公司 | Green carbon-reducing concrete additive, green carbon-reducing concrete and preparation method |
| CN113831435B (en) * | 2021-09-28 | 2023-05-09 | 安徽皖维高新材料股份有限公司 | Preparation method of raw material for PVA optical film |
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