CN118421221A - A modified styrene-butadiene latex binder and preparation method thereof - Google Patents

Abstract

The invention relates to a modified styrene-butadiene latex binder and a preparation method thereof, belonging to the technical field of styrene-butadiene latex binders. The modified styrene-butadiene latex binder comprises the following components: functional monomers, acrylic ester, butadiene, methyl styrene, hydroxyethyl acrylate, terpolymer coated titanium dioxide, silicon dioxide, an emulsifier, an initiator and deionized water; the terpolymer prepared by the invention coats titanium dioxide, so that the dispersibility and compatibility of the titanium dioxide and the silicon dioxide in a system are improved, an epoxy group of the terpolymer can react with carboxyl of styrene-butadiene latex and hydroxyl of the silicon dioxide to form chemical bond connection, in addition, the quantity of aliphatic long side chains and hydroxyl of the silicon dioxide treated by sodium hydroxide is increased, the flow of the silicon dioxide in the system is facilitated, a compact cross-linked network structure is formed, quaternary amine acrylic ester is added, and the mechanical property of a binder is improved by utilizing interaction force of amino and hydrogen bonds and ionic bonds in the system, so that the adhesive force of the adhesive on the surface of paper or other materials is enhanced.

Description

A modified styrene-butadiene latex binder and preparation method thereof

Technical Field

The invention belongs to the technical field of styrene butadiene latex binders and relates to a modified styrene butadiene latex binder and a preparation method thereof.

Background technique

Nano-silicon dioxide/titanium dioxide particles are very prone to agglomeration due to their tiny particle size, large specific surface area and high surface energy. This phenomenon leads to a significant increase in the viscosity of the silica/titanium dioxide styrene-butadiene latex composite material and a significant increase in processing energy consumption, which, to a certain extent, limits its practical application in various fields.

Styrene butadiene latex is a polymer latex made by emulsion copolymerization of butadiene and styrene monomers. It has good adhesion, and because its particle size is smaller than that of natural latex, it has better diffusion when impregnating products, but due to its non-polarity, its compatibility with fillers is poor. Therefore, it is necessary to modify the styrene butadiene latex, and carboxyl styrene butadiene latex is refined by emulsion polymerization by adding a trace amount of unsaturated carboxylic acid to this basis. In view of the high proportion of styrene components, the latex itself has excellent stability, film-forming properties and film-forming properties. The introduction of carboxyl groups significantly improves the polarity of the latex, which in turn promotes excellent compatibility with fillers, so it is widely used in papermaking, carpets, textiles and other industries; However, the introduction of a single carboxyl group still has problems with compatibility with fillers and insufficient adhesion.

Summary of the invention

The object of the present invention is to provide a modified styrene butadiene latex binder and a preparation method thereof. The terpolymer prepared by the present invention coats titanium dioxide, thereby improving the dispersibility and compatibility of titanium dioxide and silicon dioxide in the styrene butadiene latex system. The epoxy group thereof can react with the carboxyl group of the styrene butadiene latex and the hydroxyl group of silicon dioxide to form a chemical bond connection. In addition, the increase in the number of hydroxyl groups of silicon dioxide treated with aliphatic long side chains and sodium hydroxide is conducive to the flow of silicon dioxide in the styrene butadiene latex system, forming a dense cross-linked network structure, and significantly improving the mechanical properties and bonding properties. The addition of quaternary amine acrylate utilizes the interaction force between the amino group and the hydrogen bond and ionic bond in the styrene butadiene latex system to improve the mechanical properties of the binder and enhance its adhesion on the surface of paper or other materials.

The purpose of the present invention can be achieved through the following technical solutions:

A modified styrene-butadiene latex binder comprises the following components in parts by weight:

Functional monomer 3-6 parts

Acrylate 70-80 parts

Butadiene 45-60 parts

Methyl styrene 90-100 parts

Hydroxyethyl acrylate 3-5 parts

Terpolymer coated titanium dioxide 15-20 parts

Silicon dioxide 5-8 parts

Emulsifier 4-6 parts

Initiator 3.5-4 parts

Deionized water 130-150 parts.

As a preferred technical solution of the present invention, the functional monomer is one or more of methacrylic acid, maleic acid, fumaric acid and itaconic acid; the acrylic ester is prepared by mixing methyl methacrylate and quaternary ammonium acrylate in a mass ratio of 10:1-1.5; the quaternary ammonium acrylate is 3-(N,N-dimethylamino)ethyl acrylate.

As a preferred technical solution of the present invention, the emulsifier is prepared by mixing sodium dodecyl sulfate and sodium dodecylnaphthalene sulfonate in a mass ratio of 2.5:1-1.5; the initiator is one or more of azobisisobutyronitrile, azobisisoheptanenitrile, dimethyl azobisisobutyrate, azoisobutylcyanamide, tert-butyl hydroperoxide, dibenzoyl peroxide and cumene hydroperoxide.

As a preferred technical solution of the present invention, the silicon dioxide is nano-silicon dioxide that is soaked in a 30% by mass sodium hydroxide aqueous solution for 30-45 minutes, filtered to obtain the solid, washed to a pH value of 7, and then dried.

As a preferred technical solution of the present invention, the preparation of the terpolymer-coated titanium dioxide comprises the following steps:

S1. Add titanium dioxide to a solvent, heat and stir, slowly drop a coupling agent, continue stirring, cool to room temperature, centrifuge, and vacuum dry the solid to constant weight to obtain modified titanium dioxide;

S2. After ultrasonically mixing the modified titanium dioxide and the organic solvent, glycidyl methacrylate, methyl methacrylate, cardanol and isopropanol are added, and the mixture is heated and stirred under an inert atmosphere. Then, an initiator is added and stirring is continued. After cooling to room temperature, the mixture is centrifuged and the solid is vacuum dried to a constant weight to obtain a terpolymer-coated titanium dioxide.

As a preferred technical solution of the present invention, in step S1, the heating stirring is stirring at 35-40°C and 300-400r/min; the continuous stirring time is 30-45min; and the vacuum drying is drying at 70°C for 24-30h.

As a preferred technical solution of the present invention, in step S1, the mass ratio of titanium dioxide, solvent and coupling agent is 1-1.2:3:0.15-0.20; the solvent is a mixture of deionized water, anhydrous ethanol and acetic acid in a mass ratio of 1:9-9.5:0.01; the coupling agent is vinyl triethoxysilane, vinyl trimethoxysilane, γ-methacryloxypropyl trimethoxysilane or vinyl tri (β-methoxyethoxy) silane.

As a preferred technical solution of the present invention, in step S2, the inert atmosphere is a nitrogen atmosphere; the heating and stirring is stirring at 60-65°C and 300-400r/min; the continued stirring time is 5-6h; and the vacuum drying is drying at 70°C for 6-8h.

As a preferred technical solution of the present invention, in step S2, the mass ratio of the modified titanium dioxide, the organic solvent, glycidyl methacrylate, methyl methacrylate, cardanol, isopropanol and the initiator is 14-16:60-65:18-20:10-11:2.0-2.4:1.5-1.6:1.5; the organic solvent is tetrahydrofuran; and the initiator is azobisisobutyronitrile.

The invention discloses a method for preparing a modified styrene butadiene latex binder. The method comprises the following steps: stirring and mixing functional monomers, acrylate, butadiene, methyl styrene, hydroxyethyl acrylate, terpolymer-coated titanium dioxide, silicon dioxide, an emulsifier and deionized water, adding an initiator, heating and emulsifying copolymerization, adjusting the pH value, and sieving to obtain the modified styrene butadiene latex binder;

As a preferred technical solution of the present invention, in the preparation method, the stirring and mixing is carried out at 80°C for 2-3 hours; the heating emulsification copolymerization is carried out at 80-90°C for 5-8 hours; the pH value is adjusted to 6-7 using sodium hydroxide; and the screening is carried out through a 100-mesh sieve.

Beneficial effects of the present invention:

(1) The terpolymer coated titanium dioxide prepared by the present invention has titanium dioxide as a particle core and a polymer layer of cardanol-methacrylate-glycidyl acrylate coated on the outer layer of the particle core. While increasing the dispersibility and compatibility of titanium dioxide in the styrene-butadiene latex system, the epoxy groups contained in the terpolymer can not only react efficiently with the carboxyl groups in the styrene-butadiene latex system, but also react with the hydroxyl groups on the surface of silicon dioxide to form a chemical bond connection. In addition, the terpolymer coated titanium dioxide contains polar epoxy groups, hydroxyl groups and non-polar benzene ring structures, which can be used as a compatibilizer to increase the interfacial adhesion between silicon dioxide and styrene-butadiene latex, thereby significantly improving the dispersibility and compatibility of silicon dioxide in the system.

(2) The addition of epoxy groups to the terpolymer-coated titanium dioxide can improve the tensile strength and adhesion of the adhesive. The chemical name of cardanol is pentadecene phenol. It is added to the silica/styrene-butadiene latex system as a plasticizer and chain extender to enhance toughness and improve its elongation at break. In addition, the long aliphatic side chains are conducive to the sliding between molecular chains. Combined with the increase in the number of hydroxyl groups of silica treated with sodium hydroxide, it is conducive to the flow of silica in the styrene-butadiene latex system. The contact area between silica and styrene-butadiene latex particles is increased, forming a larger cross-linked network structure, making the network structure denser, and significantly improving its mechanical properties and bonding properties.

(3) The present invention improves the mechanical properties of the binder by adding quaternary ammonium acrylate and utilizing the hydrogen bonding and ionic bonding interactions between amino groups and the molecules containing hydroxyl and carboxyl groups in the styrene-butadiene latex system, thereby helping to improve the adhesion of the styrene-butadiene latex binder to the surface of paper or other materials.

Detailed ways

In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the specific implementation methods, structures, features and effects of the present invention are described in detail below in combination with the embodiments.

Example 1

A modified styrene-butadiene latex binder comprises the following components in parts by weight:

Methacrylic acid 3 parts

Acrylate 70 parts

Butadiene 45 parts

Methyl styrene 90 parts

3 parts of Hydroxyethyl Acrylate

15 parts of terpolymer coated titanium dioxide

Silicon dioxide 5 parts

Emulsifier 4 parts

Initiator 3.5 parts

Deionized water 130 parts.

The acrylic acid ester is prepared by mixing methyl methacrylate and 3-(N,N-dimethylamino)ethyl acrylate in a mass ratio of 10:1;

The emulsifier is a mixture of sodium dodecyl sulfate and sodium dodecylnaphthalene sulfonate in a mass ratio of 2.5:1; the initiator is azobisisobutyronitrile;

The silicon dioxide is obtained by soaking nano silicon dioxide in a 30% by mass sodium hydroxide aqueous solution for 30 minutes, filtering out solids, washing until the pH value is 7, and then drying.

The preparation of the terpolymer coated titanium dioxide comprises the following steps:

S1. Add titanium dioxide to the solvent, stir at 35°C and 300r/min for 30min, slowly drop vinyltriethoxysilane, continue stirring for 30min, cool to room temperature, centrifuge, take the solid and vacuum dry it at 70°C for 24h to obtain modified titanium dioxide; wherein the mass ratio of the titanium dioxide, the solvent and the coupling agent is 1:3:0.15; the solvent is a mixture of deionized water, anhydrous ethanol and acetic acid in a mass ratio of 1:9:0.01;

S2. After ultrasonically mixing the modified titanium dioxide and tetrahydrofuran, glycidyl methacrylate, methyl methacrylate, cardanol and isopropanol are added, and the mixture is stirred at 60°C and 300 r/min for 30 min under a nitrogen atmosphere. Then, azobisisobutyronitrile is added and stirring is continued for 5 h. After cooling to room temperature, the mixture is centrifuged and the solid is vacuum dried at 70°C for 6 h to obtain a terpolymer-coated titanium dioxide; wherein the mass ratio of the modified titanium dioxide, organic solvent, glycidyl methacrylate, methyl methacrylate, cardanol, isopropanol and initiator is 14:60:18:10:2.0:1.5:1.5.

A method for preparing a modified styrene-butadiene latex binder comprises the following steps:

The functional monomer, acrylate, butadiene, methyl styrene, hydroxyethyl acrylate, terpolymer-coated titanium dioxide, silicon dioxide, emulsifier and deionized water are stirred and mixed, an initiator is added, heated and emulsified for copolymerization, the pH value is adjusted, and the modified styrene-butadiene latex binder is obtained after sieving;

The stirring and mixing is carried out at 80° C. for 2 hours; the heating emulsification copolymerization is carried out at 80° C. for 5 hours; the pH value is adjusted to 6 using sodium hydroxide; and the screening is carried out through a 100-mesh sieve.

Example 2

A modified styrene-butadiene latex binder comprises the following components in parts by weight:

Methacrylic acid 4 parts

Acrylate 73 parts

Butadiene 50 parts

Methylstyrene 93 parts

Hydroxyethyl acrylate 3.7 parts

17 parts of terpolymer coated titanium dioxide

Silicon dioxide 6 parts

Emulsifier 4.7 parts

Initiator 3.7 parts

Deionized water 135 parts.

The acrylic acid ester is prepared by mixing methyl methacrylate and 3-(N,N-dimethylamino)ethyl acrylate in a mass ratio of 10:1.2;

The emulsifier is a mixture of sodium dodecyl sulfate and sodium dodecylnaphthalene sulfonate in a mass ratio of 2.5:1.2; the initiator is azobisisobutyronitrile;

The silicon dioxide is obtained by soaking nano silicon dioxide in a 30% by mass sodium hydroxide aqueous solution for 35 minutes, filtering out solids, washing until the pH value is 7, and then drying.

The preparation of the terpolymer coated titanium dioxide comprises the following steps:

S1. Add titanium dioxide to the solvent, stir at 37°C and 330r/min for 30min, slowly drop vinyltriethoxysilane, continue stirring for 35min, cool to room temperature, centrifuge, take the solid and vacuum dry it at 70°C for 25h to obtain modified titanium dioxide; wherein the mass ratio of the titanium dioxide, the solvent and the coupling agent is 1.1:3:0.17; the solvent is a mixture of deionized water, anhydrous ethanol and acetic acid in a mass ratio of 1:9.2:0.01;

S2. After ultrasonically mixing the modified titanium dioxide and tetrahydrofuran, glycidyl methacrylate, methyl methacrylate, cardanol and isopropanol are added, and the mixture is stirred at 62°C and 330 r/min for 30 min under a nitrogen atmosphere. Then, azobisisobutyronitrile is added and stirring is continued for 5.5 h. After cooling to room temperature, the mixture is centrifuged and the solid is vacuum dried at 70°C for 6.5 h to obtain a terpolymer-coated titanium dioxide; wherein the mass ratio of the modified titanium dioxide, organic solvent, glycidyl methacrylate, methyl methacrylate, cardanol, isopropanol and initiator is 14.7:62:18.7:10.5:2.1:1.55:1.5.

A method for preparing a modified styrene-butadiene latex binder comprises the following steps:

The functional monomer, acrylate, butadiene, methyl styrene, hydroxyethyl acrylate, terpolymer-coated titanium dioxide, silicon dioxide, emulsifier and deionized water are stirred and mixed, an initiator is added, heated and emulsified for copolymerization, the pH value is adjusted, and the modified styrene-butadiene latex binder is obtained after sieving;

The stirring and mixing is carried out at 80° C. for 2.5 hours; the heating emulsification copolymerization is carried out at 83° C. for 6 hours; the pH value is adjusted to 6.5 using sodium hydroxide; and the screening is carried out through a 100-mesh sieve.

Example 3

A modified styrene-butadiene latex binder comprises the following components in parts by weight:

Methacrylic acid 5 parts

Acrylate 77 parts

Butadiene 55 parts

Methylstyrene 97 parts

Hydroxyethyl acrylate 4.3 parts

18 parts of terpolymer coated titanium dioxide

Silicon dioxide 7 parts

Emulsifier 5.3 parts

Initiator 3.8 parts

Deionized water 145 parts.

The acrylic acid ester is prepared by mixing methyl methacrylate and 3-(N,N-dimethylamino)ethyl acrylate in a mass ratio of 10:1.3;

The emulsifier is a mixture of sodium dodecyl sulfate and sodium dodecylnaphthalene sulfonate in a mass ratio of 2.5:1.3; the initiator is azobisisobutyronitrile;

The silicon dioxide is obtained by soaking nano silicon dioxide in a 30% by mass sodium hydroxide aqueous solution for 40 minutes, filtering out solids, washing until the pH value is 7, and then drying.

The preparation of the terpolymer coated titanium dioxide comprises the following steps:

S1. Add titanium dioxide to the solvent, stir at 38°C and 365r/min for 30min, slowly drop vinyltriethoxysilane, continue stirring for 40min, cool to room temperature, centrifuge, take the solid and vacuum dry it at 70°C for 25h to obtain modified titanium dioxide; wherein the mass ratio of the titanium dioxide, the solvent and the coupling agent is 1.1:3:0.18; the solvent is a mixture of deionized water, anhydrous ethanol and acetic acid in a mass ratio of 1:9.3:0.01;

S2. After ultrasonically mixing the modified titanium dioxide and tetrahydrofuran, glycidyl methacrylate, methyl methacrylate, cardanol and isopropanol are added, and the mixture is stirred at 63°C and 367 r/min for 30 min under a nitrogen atmosphere. Then, azobisisobutyronitrile is added and stirring is continued for 5.7 h. After cooling to room temperature, the mixture is centrifuged and the solid is vacuum dried at 70°C for 7.3 h to obtain a terpolymer-coated titanium dioxide; wherein the mass ratio of the modified titanium dioxide, organic solvent, glycidyl methacrylate, methyl methacrylate, cardanol, isopropanol and initiator is 15.5:63:19.5:10.7:2.5:1.55:1.5.

A method for preparing a modified styrene-butadiene latex binder comprises the following steps:

The functional monomer, acrylate, butadiene, methyl styrene, hydroxyethyl acrylate, terpolymer-coated titanium dioxide, silicon dioxide, emulsifier and deionized water are stirred and mixed, an initiator is added, heated and emulsified for copolymerization, the pH value is adjusted, and the modified styrene-butadiene latex binder is obtained after sieving;

The stirring and mixing is carried out at 80° C. for 2.5 hours; the heating emulsification copolymerization is carried out at 85° C. for 7 hours; the pH value is adjusted to 6.5 using sodium hydroxide; and the screening is carried out through a 100-mesh sieve.

Example 4

A modified styrene-butadiene latex binder comprises the following components in parts by weight:

Methacrylic acid 6 parts

Acrylate 80 parts

Butadiene 60 parts

Methyl styrene 100 parts

Hydroxyethyl acrylate 5 parts

20 parts of terpolymer coated titanium dioxide

Silicon dioxide 8 parts

Emulsifier 6 parts

Initiator 4 parts

Deionized water 150 parts.

The acrylic acid ester is prepared by mixing methyl methacrylate and 3-(N,N-dimethylamino)ethyl acrylate in a mass ratio of 10:1.5;

The emulsifier is a mixture of sodium dodecyl sulfate and sodium dodecylnaphthalene sulfonate in a mass ratio of 2.5:1.5; the initiator is azobisisobutyronitrile;

The silicon dioxide is obtained by soaking nano silicon dioxide in a 30% by mass sodium hydroxide aqueous solution for 45 minutes, filtering out solids, washing until the pH value is 7, and then drying.

The preparation of the terpolymer coated titanium dioxide comprises the following steps:

S1. Add titanium dioxide to a solvent, stir at 40°C and 400 r/min for 30 min, slowly drop vinyltriethoxysilane, continue stirring for 45 min, cool to room temperature, centrifuge, take the solid and vacuum dry it at 70°C for 30 h to obtain modified titanium dioxide; wherein the mass ratio of the titanium dioxide, the solvent and the coupling agent is 1.2:3:0.20; the solvent is a mixture of deionized water, anhydrous ethanol and acetic acid in a mass ratio of 1:9.5:0.01;

S2. After ultrasonically mixing the modified titanium dioxide and tetrahydrofuran, glycidyl methacrylate, methyl methacrylate, cardanol and isopropanol are added, and the mixture is stirred at 65°C and 400 r/min for 30 min under a nitrogen atmosphere. Then, azobisisobutyronitrile is added and stirring is continued for 6 h. After cooling to room temperature, the mixture is centrifuged and the solid is vacuum dried at 70°C for 8 h to obtain a terpolymer-coated titanium dioxide; wherein the mass ratio of the modified titanium dioxide, organic solvent, glycidyl methacrylate, methyl methacrylate, cardanol, isopropanol and initiator is 16:65:20:11:2.4:1.6:1.5.

A method for preparing a modified styrene-butadiene latex binder comprises the following steps:

The functional monomer, acrylate, butadiene, methyl styrene, hydroxyethyl acrylate, terpolymer-coated titanium dioxide, silicon dioxide, emulsifier and deionized water are stirred and mixed, an initiator is added, heated and emulsified for copolymerization, the pH value is adjusted, and the modified styrene-butadiene latex binder is obtained after sieving;

The stirring and mixing is carried out at 80° C. for 3 hours; the heating emulsification copolymerization is carried out at 90° C. for 8 hours; the pH value is adjusted to 7 using sodium hydroxide; and the screening is carried out through a 100-mesh sieve.

Comparative Example 1

Compared with Example 2, the difference in Comparative Example 1 is that the mixture consisting of the terpolymer and titanium dioxide replaces the terpolymer to coat the titanium dioxide;

The preparation of the mixture comprises the following steps:

Add glycidyl methacrylate, methyl methacrylate, cardanol and isopropanol to tetrahydrofuran, stir for 30 min at 62° C. and 330 r/min under a nitrogen atmosphere, add azobisisobutyronitrile and continue stirring for 5.5 h, cool to room temperature, centrifuge, take the solid and dry it in vacuum at 70° C. for 6.5 h, add titanium dioxide and stir and mix to obtain a mixture; wherein the mass ratio of titanium dioxide, organic solvent, glycidyl methacrylate, methyl methacrylate, cardanol, isopropanol and initiator is 14.7:62:18.7:10.5:2.1:1.55:1.5;

The remaining components, preparation steps and parameters were the same.

Comparative Example 2

Compared with Example 2, the difference of Comparative Example 2 is that Comparative Example 2 uses 4-allylphenol instead of cardanol, and the other components, preparation steps and parameters are the same.

Comparative Example 3

Compared with Example 2, Comparative Example 3 is different in that the acrylic acid ester in Comparative Example 3 is methyl methacrylate, that is, 3-(N,N-dimethylamino)ethyl acrylate is not used, and the other components, preparation steps and parameters are the same.

Comparative Example 4

Compared with Example 2, Comparative Example 4 is different in that the silicon dioxide in Comparative Example 4 is nano silicon dioxide, that is, it is not treated with a sodium hydroxide aqueous solution, and the other components, preparation steps and parameters are the same.

The modified styrene-butadiene latex binders prepared in Examples 1-4 and Comparative Examples 1-4 were subjected to the following tests; the test results are shown in Table 1.

Bond strength test: using a universal tensile testing machine, tested according to GB/T2791-1995T;

Mechanical properties test: tensile strength and elongation at break are tested according to GB/T8655-2019.

Table 1

Bond strength (N/m) Tensile strength (MPa) Elongation at break (%) Example 1 7.23 36.3 607 Example 2 7.27 36.6 615 Example 3 7.25 36.5 613 Example 4 7.23 36.4 609 Comparative Example 1 5.13 25.3 411 Comparative Example 2 5.62 28.1 449 Comparative Example 3 6.22 31.1 504 Comparative Example 4 6.35 31.7 521

It can be seen from the test results in Table 1 that compared with comparative examples 1-4, the bonding strength, tensile strength and elongation at break of the modified styrene-butadiene latex binder prepared in embodiments 1-4 of the present invention are better than those in comparative examples 1-4; among them, the tensile strength and elongation at break of the binder prepared by the scheme of the present invention are significantly different from those of comparative examples 1-4.

The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims (10)

1. A modified styrene-butadiene latex binder, characterized in that it comprises the following components in parts by weight: Functional monomer 3-6 parts Acrylate 70-80 parts Butadiene 45-60 parts Methyl styrene 90-100 parts Hydroxyethyl acrylate 3-5 parts Terpolymer coated titanium dioxide 15-20 parts Silicon dioxide 5-8 parts Emulsifier 4-6 parts Initiator 3.5-4 parts Deionized water 130-150 parts. 2. A modified styrene-butadiene latex binder according to claim 1, characterized in that: The functional monomer is one or more of methacrylic acid, maleic acid, fumaric acid and itaconic acid; the acrylic ester is prepared by mixing methyl methacrylate and quaternary ammonium acrylate in a mass ratio of 10:1-1.5; the quaternary ammonium acrylate is 3-(N,N-dimethylamino)ethyl acrylate. 3. A modified styrene-butadiene latex binder according to claim 1, characterized in that: the emulsifier is a mixture of sodium dodecyl sulfate and sodium dodecylnaphthalene sulfonate in a mass ratio of 2.5:1-1.5; the initiator is one or more of azobisisobutyronitrile, azobisisoheptanenitrile, dimethyl azobisisobutyrate, azoisobutylcyanamide, tert-butyl hydroperoxide, dibenzoyl peroxide and cumene hydroperoxide. 4. A modified styrene-butadiene latex binder according to claim 1, characterized in that the silicon dioxide is nano silicon dioxide which is soaked in a 30% by mass sodium hydroxide aqueous solution for 30-45 minutes, filtered to take out the solid, washed to a pH value of 7 and dried. 5. The modified styrene-butadiene latex binder according to claim 1, characterized in that the preparation of the terpolymer coated titanium dioxide comprises the following steps: S1. Add titanium dioxide to a solvent, heat and stir, slowly drop a coupling agent, continue stirring, cool to room temperature, centrifuge, and vacuum dry the solid to constant weight to obtain modified titanium dioxide; S2. After ultrasonically mixing the modified titanium dioxide and the organic solvent, glycidyl methacrylate, methyl methacrylate, cardanol and isopropanol are added, and the mixture is heated and stirred under an inert atmosphere. Then, an initiator is added and stirring is continued. After cooling to room temperature, the mixture is centrifuged and the solid is vacuum dried to a constant weight to obtain a terpolymer-coated titanium dioxide. 6. A modified styrene-butadiene latex binder according to claim 5, characterized in that: in step S1, the heating and stirring is stirring at 35-40°C and 300-400r/min; the continuous stirring time is 30-45min; the vacuum drying is drying at 70°C for 24-30h. 7. A modified styrene-butadiene latex binder according to claim 5, characterized in that: in step S1, the mass ratio of titanium dioxide, solvent and coupling agent is 1-1.2:3:0.15-0.20; the solvent is a mixture of deionized water, anhydrous ethanol and acetic acid in a mass ratio of 1:9-9.5:0.01; the coupling agent is vinyl triethoxysilane, vinyl trimethoxysilane, γ-methacryloxypropyl trimethoxysilane or vinyl tri (β-methoxyethoxy) silane. 8. A modified styrene-butadiene latex binder according to claim 5, characterized in that: in step S2, the inert atmosphere is a nitrogen atmosphere; the heating and stirring is stirring at 60-65°C and 300-400r/min; the continuous stirring time is 5-6h; the vacuum drying is drying at 70°C for 6-8h. 9. A modified styrene-butadiene latex binder according to claim 5, characterized in that: in step S2, the mass ratio of the modified titanium dioxide, organic solvent, glycidyl methacrylate, methyl methacrylate, cardanol, isopropanol and initiator is 14-16:60-65:18-20:10-11:2.0-2.4:1.5-1.6:1.5; the organic solvent is tetrahydrofuran; and the initiator is azobisisobutyronitrile. 10. A method for preparing a modified styrene butadiene latex binder according to any one of claims 1 to 9, characterized in that the method comprises the following steps: mixing functional monomers, acrylate, butadiene, methyl styrene, hydroxyethyl acrylate, terpolymer-coated titanium dioxide, silicon dioxide, emulsifier and deionized water, adding an initiator, heating and emulsifying copolymerization, adjusting the pH value, and sieving to obtain the modified styrene butadiene latex binder; The stirring and mixing is carried out at 80° C. for 2-3 hours; the heating emulsification copolymerization is carried out at 80-90° C. for 5-8 hours; the pH value is adjusted to 6-7 using sodium hydroxide; and the screening is carried out through a 100-mesh sieve.