Carboxylic butadiene-styrene latex for thermo-sensitive paper and preparation process of carboxylic butadiene-styrene latex

Abstract

The invention relates to the technical field of styrene-butadiene latex synthesis, and particularly discloses carboxylic styrene-butadiene latex for thermo-sensitive paper and a preparation process of the carboxylic styrene-butadiene latex. The invention discloses carboxylic butadiene-styrene latex for thermo-sensitive paper. The carboxylic butadiene-styrene latex is prepared from the following raw material components in parts by weight: 80 to 120 parts of deionized water, 50 to 60 parts of butadiene, 40 to 50 parts of styrene, 1 to 10 parts of polar monomer, 3 to 5 parts of crosslinking monomer, 2 to 5 parts of dicarboxyl unsaturated carboxylic acid derivative, 0.6 to 1 part of initiator A, 0.4 to 0.8 part of molecular weight regulator, 1 to 3 parts of emulsifier, 1.2 to 1.6 parts of neutralizer, 0.1 to 0.5 part of defoaming agent, 0.2 to 0.8 part of antioxidant, 10 to 20 parts of silane modified nano silicon dioxide and 0.2 to 0.4 part of initiator B, the adhesive is prepared from the following components in parts by weight: 10-12 parts of plasticizer, 0.2-0.4 part of catalyst, 1-3 parts of diphenyl phthalate, 1-3 parts of carbodiimide and 2-4 parts of adhesive.

Description

Technical Field

[0001] The present application relates to the technical field of styrene butadiene latex synthesis, and in particular to carboxylated styrene butadiene latex for thermal paper and a preparation process thereof. Background Art

[0002] In thermal paper, the main function of adhesive is to evenly bond the hidden colorless dye, developer, sensitizer, filler and other additives to the base paper through coating and drying. The adhesive used for thermal paper requires strong bonding strength, the ability to isolate colorants, developers, pigments and stabilizers, and certain surface strength and water resistance. Carboxylated styrene butadiene latex has good compatibility with other components of thermal coatings, the coating is stable, and the thermal paper obtained has good smoothness and water resistance, and good color development performance, but the bonding strength of commonly used carboxylated styrene butadiene latex needs to be further improved. Summary of the invention

[0003] In order to improve the bonding strength of carboxylated styrene butadiene latex, the present application provides a carboxylated styrene butadiene latex for thermal paper and a preparation process thereof.

[0004] In the first aspect, the present application provides a carboxylated styrene-butadiene latex for thermal paper, which adopts the following technical solution: The invention discloses a carboxylated styrene butadiene latex for thermal paper. The raw materials of the carboxylated styrene butadiene latex include the following components in parts by weight: 80-120 parts of deionized water, 50-60 parts of butadiene, 40-50 parts of styrene, 1-10 parts of polar monomers, 3-5 parts of crosslinking monomers, 2-5 parts of dicarboxyl unsaturated carboxylic acid derivatives, 0.6-1 parts of initiator A, 0.4-0.8 parts of molecular weight regulator, 1-3 parts of emulsifier, 1.2-1.6 parts of neutralizer, 0.1-0.5 parts of defoamer, 0.2-0.8 parts of antioxidant, 10-20 parts of silane-modified nano-silicon dioxide, 0.2-0.4 parts of initiator B, 10-12 parts of plasticizer, 0.2-0.4 parts of catalyst, 1-3 parts of diphenyl phthalate, 1-3 parts of carbodiimide and 2-4 parts of adhesive.

[0005] By adopting the above technical scheme, silane-modified nano-silica increases the mechanical strength and durability of the latex, making it more suitable for various application environments. The silane on the surface can not only improve the dispersion performance of the nano-silica, but also improve the coordination of the various components. The mutual coordination of diphenyl phthalate, carbodiimide and adhesive is then used to improve the bonding strength of the carboxylated styrene butadiene latex. The plasticizer improves the flexibility and ductility of the latex, further improving the bonding performance.

[0006] In a specific embodiment, the preparation method of the silane-modified nano-silicon dioxide comprises the following steps: γ-aminopropyltriethoxysilane, ethanol and water are stirred and mixed to obtain a spraying liquid; The nano-silicon dioxide is stirred, and during the stirring process, a spraying liquid is sprayed into the nano-silicon dioxide. After the spraying is completed, the nano-silicon dioxide is stirred and dried to obtain silane-modified nano-silicon dioxide.

[0007] By adopting the above technical scheme, γ-aminopropyltriethoxysilane is firstly dissolved in ethanol, and then spraying is performed while stirring the nano-silica. After the spraying is completed, stirring is continued and drying is performed to obtain silane-modified nano-silica.

[0008] In a specific embodiment, the weight ratio of the spraying liquid to the nano-silicon dioxide is 1:(13-14).

[0009] By adopting the above technical solution, the ratio of the spraying liquid to the nano-silicon dioxide is further limited, thereby further improving the modification effect of the nano-silicon dioxide.

[0010] In a specific embodiment, the initiator B includes ammonium persulfate.

[0011] By adopting the above technical solution, ammonium persulfate can effectively promote the polymerization reaction of carboxylated styrene butadiene latex, increase the molecular weight and uniformity of the product, and thus significantly improve the bonding strength of the carboxylated styrene butadiene latex.

[0012] In a specific embodiment, the plasticizer includes one or more of diisononyl phthalate, di-2-ethylhexyl phthalate, and dioctyl phthalate.

[0013] By adopting the above technical scheme, diisononyl phthalate, di-2-ethylhexyl phthalate and dioctyl phthalate can significantly improve the flexibility and processing performance of carboxylated styrene butadiene latex, thereby improving its bonding strength.

[0014] In a specific embodiment, the catalyst includes one of tetrabutyl titanate and aluminum triacetylacetonate.

[0015] In the second aspect, the present application provides a process for preparing carboxylated styrene butadiene latex for thermal paper, which adopts the following technical scheme: A preparation process of carboxylated styrene-butadiene latex for thermal paper comprises the following steps: Preparation of mixed solution: stir and mix part of deionized water, part of emulsifier, part of dicarboxylic unsaturated carboxylic acid derivative, part of cross-linking monomer and neutralizer to obtain mixed solution A; stir and mix the remaining deionized water, the remaining emulsifier and part of dicarboxylic unsaturated carboxylic acid derivative to obtain mixed solution B; Preparation of reaction liquid A: under vacuum conditions, mixed liquid A, part of styrene, part of molecular weight regulator and part of butadiene are mixed, heated to 75-80°C, part of initiator A is added, the temperature is continued to be raised to 85-88°C, heating is stopped, and then the temperature is controlled at 92-95°C, and the reaction is carried out for 10-30 minutes; when the temperature is controlled, mixed liquid B, the remaining styrene, the remaining molecular weight regulator and the remaining butadiene are added dropwise to the reaction liquid, and the temperature is continuously controlled at 92-95°C, and the reaction is continued; sampling and monitoring are performed during the reaction, and when the solid content of the sample reaches 70-75% of the theoretical solid content, the addition of mixed liquid B is stopped, the remaining dicarboxylic unsaturated carboxylic acid derivative is added, and stirring is carried out for 10-12 minutes, and then the remaining mixed liquid B is continued to be added dropwise until the addition is completed, and the addition time is controlled at 3-5 hours to obtain reaction liquid A; Preparation of colostrum: The reaction liquid A is heated to 95-98°C, kept warm for 1-2 hours, the pH value of the reaction liquid is adjusted, and then a defoaming agent is added for degassing; the VOC value of the reaction liquid A is monitored, and when the VOC value of the reaction liquid A drops below 200ppm, the reaction liquid A is cooled to below 45°C, and then an antioxidant is added, and the pH value of the reaction liquid is adjusted again. After the material is filtered, colostrum is obtained; Compounding: Mix colostrum with the catalyst, then add initiator B, heat the reaction under the protection of inert gas, then add plasticizer and silane-modified nano-silica, stir until evenly dispersed, cool, and finally add diphenyl phthalate, carbodiimide, and adhesive, stir and mix evenly, filter, and obtain carboxylated styrene butadiene latex for thermal paper.

[0016] By adopting the above technical scheme, colostrum is first polymerized, then modified by plasticizer and silane-modified nano-silica under the action of catalyst and initiator B, and finally mixed with diphenyl phthalate, carbodiimide and adhesive, thereby obtaining carboxylated styrene-butadiene latex for thermal paper with high bonding strength.

[0017] In a specific embodiment, in the compounding step, the heating temperature is 80-90° C. and the reaction time is 1-3 h.

[0018] In a specific embodiment, in the compounding step, filtration is performed using a filter membrane with a pore size of 0.2-0.5 microns.

[0019] By adopting the above technical solution, using a filter membrane with a pore size of 0.2-0.5 microns for filtration can effectively remove impurities and large particles in the carboxylated styrene butadiene latex, ensuring the purity and stability of the final product.

[0020] In summary, the present application includes at least one of the following beneficial technical effects: 1. The silane-modified nano-silica in the present application increases the mechanical strength and durability of the latex, making it more suitable for various application environments, and the silane on the surface can not only improve the dispersion performance of the nano-silica, but also improve the coordination of each component, and then utilize the mutual coordination of diphenyl phthalate, carbodiimide, and adhesive to improve the bonding strength of the obtained carboxylated styrene butadiene latex, and the plasticizer improves the flexibility and ductility of the latex, further improving the bonding performance; 2. In the present application, γ-aminopropyltriethoxysilane is first dissolved in ethanol, and then sprayed while stirring the nano-silica. After the spraying is completed, the nano-silica is continuously stirred and dried to obtain silane-modified nano-silica. 3. The process in the present application first polymerizes to obtain colostrum, then modifies it with a plasticizer and silane-modified nano-silica under the action of a catalyst and an initiator B, and finally mixes diphenyl phthalate, carbodiimide, and an adhesive to obtain a carboxylated styrene-butadiene latex for thermal paper with a high bonding strength. DETAILED DESCRIPTION

[0021] The present application is further described in detail below with reference to the embodiments.

[0022] All raw materials in the embodiments can be obtained commercially. The plasticizer includes but is not limited to a mixture of one or more of diisononyl phthalate, di-2-ethylhexyl phthalate, and dioctyl phthalate, preferably diisononyl phthalate in this application; the catalyst includes but is not limited to one of tetrabutyl titanate and aluminum triacetylacetonate, preferably tetrabutyl titanate in this application; the binder includes but is not limited to a mixture of one or more of polyvinyl alcohol, hydroxyethyl cellulose, and starch, preferably polyvinyl alcohol in this application.

[0023] Preparation Example Preparation Example 1 Preparation Example 1 provides a method for preparing silane-modified nano-silicon dioxide, comprising the following steps: Stir and mix γ-aminopropyltriethoxysilane, ethanol and water to obtain a spraying liquid; wherein the weight ratio of γ-aminopropyltriethoxysilane, ethanol and water is 5:18:2; The nano-silica was stirred, and during the stirring process, the spraying liquid was slowly sprayed into the nano-silica. After the spraying was completed, the stirring was continued for 0.5 h, and then dried at 80° C. for 0.5 h to obtain silane-modified nano-silica; wherein the weight ratio of the spraying liquid to the nano-silica was 1:12.5.

[0024] Preparation Example 2 Preparation Example 2 provides a method for preparing silane-modified nano-silicon dioxide, comprising the following steps: Stir and mix γ-aminopropyltriethoxysilane, ethanol and water to obtain a spraying liquid; wherein the weight ratio of γ-aminopropyltriethoxysilane, ethanol and water is 5:18:2; The nano-silica was stirred, and during the stirring process, the spraying liquid was slowly sprayed into the nano-silica. After the spraying was completed, the stirring was continued for 0.5 h, and then dried at 80° C. for 0.5 h to obtain silane-modified nano-silica; wherein the weight ratio of the spraying liquid to the nano-silica was 1:13.

[0025] Preparation Example 3 Preparation Example 3 provides a method for preparing silane-modified nano-silicon dioxide, comprising the following steps: Stir and mix γ-aminopropyltriethoxysilane, ethanol and water to obtain a spraying liquid; wherein the weight ratio of γ-aminopropyltriethoxysilane, ethanol and water is 5:18:2; The nano-silica was stirred, and during the stirring process, the spraying liquid was slowly sprayed into the nano-silica. After the spraying was completed, the stirring was continued for 0.5 h, and then the mixture was dried at 80° C. for 0.5 h to obtain silane-modified nano-silica; wherein the weight ratio of the spraying liquid to the nano-silica was 1:13.5.

[0026] Preparation Example 4 Preparation Example 4 provides a method for preparing silane-modified nano-silicon dioxide, comprising the following steps: Stir and mix γ-aminopropyltriethoxysilane, ethanol and water to obtain a spraying liquid; wherein the weight ratio of γ-aminopropyltriethoxysilane, ethanol and water is 5:18:2; The nano-silica was stirred, and during the stirring process, the spraying liquid was slowly sprayed into the nano-silica. After the spraying was completed, the stirring was continued for 0.5 h, and then the mixture was dried at 80° C. for 0.5 h to obtain silane-modified nano-silica; wherein the weight ratio of the spraying liquid to the nano-silica was 1:14.

[0027] Preparation Example 5 Preparation Example 5 provides a method for preparing silane-modified nano-silicon dioxide, comprising the following steps: Stir and mix γ-aminopropyltriethoxysilane, ethanol and water to obtain a spraying liquid; wherein the weight ratio of γ-aminopropyltriethoxysilane, ethanol and water is 5:18:2; The nano-silica was stirred, and during the stirring process, the spraying liquid was slowly sprayed into the nano-silica. After the spraying was completed, the stirring was continued for 0.5 h, and then dried at 80° C. for 0.5 h to obtain silane-modified nano-silica; wherein the weight ratio of the spraying liquid to the nano-silica was 1:14.5. Example

[0028] Example 1 Embodiment 1 provides a preparation process of carboxylated styrene-butadiene latex for thermal paper, comprising the following steps: Preparation of mixed solution: 40 kg of deionized water, 0.1 kg of emulsifier, 0.5 kg of dicarboxylic unsaturated carboxylic acid derivative, 0.3 kg of cross-linking monomer and 1.2 kg of neutralizer are stirred and mixed to obtain mixed solution A; 40 kg of deionized water, 0.9 kg of emulsifier and 1.2 kg of dicarboxylic unsaturated carboxylic acid derivative are stirred and mixed to obtain mixed solution B; wherein the emulsifier is sodium dodecyl sulfate; the dicarboxylic unsaturated carboxylic acid derivative is maleic anhydride, which will not self-polymerize and can be completely grafted onto the latex molecular chain; the cross-linking monomer is hydroxyethyl acrylate; the neutralizer is sodium bicarbonate; Preparation of reaction solution A: under vacuum conditions, mixed solution A, 4 kg styrene, 0.04 kg molecular weight regulator and 5 kg butadiene are mixed, the temperature is raised to 75°C, 0.3 kg initiator A is added, the temperature is continued to rise to 85°C, heating is stopped, and then the temperature is controlled at 92°C for reaction for 30 minutes; when the temperature is controlled, mixed solution B, 36 kg styrene, 0.36 kg molecular weight regulator and 45 kg butadiene are added dropwise to the reaction solution, and the temperature is continuously controlled at 92°C for reaction; sampling and monitoring are performed during the reaction, and when the sampled solid content reaches 70-75% of the theoretical solid content, the dropwise addition of mixed solution B is stopped, 0.3 kg dicarboxylic unsaturated carboxylic acid derivative is added, stirring is performed for 12 minutes, and then the remaining mixed solution B is continued to be added dropwise until the dropwise addition is completed, and the dropwise addition time is controlled at 3 hours to obtain reaction solution A; wherein the molecular weight regulator is tert-dodecyl mercaptan; and initiator A is ammonium persulfate; Preparation of colostrum: The reaction liquid A is heated to 95°C, kept warm for 2 hours, the pH value of the reaction liquid A is adjusted, and then 0.1 kg of defoaming agent is added for degassing; the VOC value of the reaction liquid A is monitored, and when the VOC value of the reaction liquid A drops below 200 ppm, the reaction liquid A is cooled to below 45°C, and then 0.2 kg of antioxidant is added, and the pH value of the reaction liquid is adjusted again. After the material is discharged and filtered, colostrum is obtained; wherein the defoaming agent is polydimethylsiloxane; and the antioxidant is dilauryl thiodipropionate emulsion; Compounding: Mix colostrum with 0.2 kg of catalyst, then add 0.2 kg of initiator B, heat to 80 ° C under the protection of inert gas for reaction for 3 hours, then add 10 kg of plasticizer and 10 kg of silane-modified nano-silica in Preparation Example 1, stir until uniformly dispersed, cool, and finally add 1 kg of diphenyl phthalate, 1 kg of carbodiimide, and 2 kg of adhesive, stir and mix evenly, filter with a filter membrane with a pore size of 0.2-0.5 microns to obtain carboxylated styrene butadiene latex for thermal paper; wherein the catalyst is tetrabutyl titanate; initiator B is ammonium persulfate; the plasticizer is diisononyl phthalate; and the adhesive is polyvinyl alcohol.

[0029] Example 2 Embodiment 2 provides a preparation process of carboxylated styrene-butadiene latex for thermal paper, comprising the following steps: Preparation of mixed solution: 50 kg of deionized water, 0.2 kg of emulsifier, 1 kg of dicarboxylic unsaturated carboxylic acid derivative, 0.4 kg of cross-linking monomer and 1.4 kg of neutralizer were stirred and mixed to obtain mixed solution A; 50 kg of deionized water, 1.8 kg of emulsifier and 2.4 kg of dicarboxylic unsaturated carboxylic acid derivative were stirred and mixed to obtain mixed solution B; wherein the emulsifier is sodium lauryl sulfate; the dicarboxylic unsaturated carboxylic acid derivative is maleic anhydride; the cross-linking monomer is hydroxyethyl acrylate; and the neutralizer is sodium bicarbonate; Preparation of reaction solution A: under vacuum conditions, mixed solution A, 4.5 kg styrene, 0.06 kg molecular weight regulator and 5.5 kg butadiene are mixed, heated to 75°C, 0.4 kg initiator A is added, the temperature is continued to rise to 85°C, heating is stopped, and then the temperature is controlled at 92°C for reaction for 30 minutes; when the temperature is controlled, mixed solution B, 40.5 kg styrene, 0.54 kg molecular weight regulator and 49.5 kg butadiene are added dropwise to the reaction solution, and the temperature is continuously controlled at 92°C for reaction; sampling and monitoring are performed during the reaction, and when the sampled solid content reaches 70-75% of the theoretical solid content, the addition of mixed solution B is stopped, 0.6 kg dicarboxylic unsaturated carboxylic acid derivative is added, stirred for 12 minutes, and then the remaining mixed solution B is continued to be added dropwise until the addition is completed, and the addition time is controlled at 3 hours to obtain reaction solution A; wherein the molecular weight regulator is tert-dodecyl mercaptan; and initiator A is ammonium persulfate; Preparation of colostrum: The reaction liquid A is heated to 95°C, kept warm for 2 hours, the pH value of the reaction liquid A is adjusted, and then 0.3 kg of defoaming agent is added for degassing; the VOC value of the reaction liquid A is monitored, and when the VOC value of the reaction liquid A drops below 200 ppm, the reaction liquid A is cooled to below 45°C, and then 0.5 kg of antioxidant is added, and the pH value of the reaction liquid is adjusted again. After the material is discharged and filtered, colostrum is obtained; wherein the defoaming agent is polydimethylsiloxane; and the antioxidant is dilauryl thiodipropionate emulsion; Compounding: Mix colostrum with 0.3 kg of catalyst, then add 0.3 kg of initiator B, heat to 80 ° C under the protection of inert gas for 3 hours, then add 11 kg of plasticizer and 15 kg of silane-modified nano-silica in Preparation Example 1, stir until uniformly dispersed, cool, and finally add 2 kg of diphenyl phthalate, 2 kg of carbodiimide, and 3 kg of adhesive, stir and mix evenly, filter with a filter membrane with a pore size of 0.2-0.5 microns, and obtain carboxylated styrene butadiene latex for thermal paper; wherein the catalyst is tetrabutyl titanate; initiator B is ammonium persulfate; the plasticizer is diisononyl phthalate; and the adhesive is polyvinyl alcohol.

[0030] Example 3 Embodiment 3 provides a preparation process of carboxylated styrene-butadiene latex for thermal paper, comprising the following steps: Preparation of mixed solution: 60 kg of deionized water, 0.3 kg of emulsifier, 1.25 kg of dicarboxylic unsaturated carboxylic acid derivative, 0.5 kg of cross-linking monomer, and 1.6 kg of neutralizer were stirred and mixed to obtain mixed solution A; 60 kg of deionized water, 2.7 kg of emulsifier, and 3 kg of dicarboxylic unsaturated carboxylic acid derivative were stirred and mixed to obtain mixed solution B; wherein the emulsifier is sodium dodecyl sulfate; the dicarboxylic unsaturated carboxylic acid derivative is maleic anhydride; the cross-linking monomer is hydroxyethyl acrylate; and the neutralizer is sodium bicarbonate; Preparation of reaction solution A: under vacuum conditions, mixed solution A, 5 kg styrene, 0.08 kg molecular weight regulator and 6 kg butadiene are mixed, the temperature is raised to 75°C, 0.5 kg initiator A is added, the temperature is continued to rise to 85°C, heating is stopped, and then the temperature is controlled at 92°C for reaction for 30 min; when the temperature is controlled, mixed solution B, 45 kg styrene, 0.72 kg molecular weight regulator and 54 kg butadiene are added dropwise to the reaction solution, and the temperature is continuously controlled at 92°C for reaction; sampling and monitoring are performed during the reaction, and when the sampled solid content reaches 70-75% of the theoretical solid content, the addition of mixed solution B is stopped, 0.75 kg dicarboxylic unsaturated carboxylic acid derivative is added, stirring is performed for 12 min, and then the remaining mixed solution B is continued to be added dropwise until the addition is completed, and the addition time is controlled at 3 h to obtain reaction solution A; wherein the molecular weight regulator is tert-dodecyl mercaptan; and initiator A is ammonium persulfate; Preparation of colostrum: The reaction liquid A is heated to 95°C, kept warm for 2 hours, the pH value of the reaction liquid A is adjusted, and then 0.5 kg of defoaming agent is added for degassing; the VOC value of the reaction liquid A is monitored, and when the VOC value of the reaction liquid A drops below 200 ppm, the reaction liquid A is cooled to below 45°C, and then 0.8 kg of antioxidant is added, the pH value of the reaction liquid is adjusted again, and the colostrum is obtained after the material is filtered; wherein the defoaming agent is polydimethylsiloxane; and the antioxidant is dilauryl thiodipropionate emulsion; Compounding: Mix colostrum with 0.4 kg of catalyst, then add 0.4 kg of initiator B, heat to 80 ° C under the protection of inert gas for reaction for 3 hours, then add 12 kg of plasticizer and 20 kg of silane-modified nano-silica in Preparation Example 1, stir until uniformly dispersed, cool, and finally add 3 kg of diphenyl phthalate, 3 kg of carbodiimide, and 4 kg of adhesive, stir and mix evenly, filter with a filter membrane with a pore size of 0.2-0.5 microns, and obtain carboxylated styrene butadiene latex for thermal paper; wherein the catalyst is tetrabutyl titanate; initiator B is ammonium persulfate; the plasticizer is diisononyl phthalate; and the adhesive is polyvinyl alcohol.

[0031] Example 4 The difference between Example 4 and Example 2 is that the silane-modified nano-silica is the silane-modified nano-silica in Preparation Example 2; the remaining steps are consistent with Example 2.

[0032] Example 5 The difference between Example 5 and Example 2 is that the silane-modified nano-silica is the silane-modified nano-silica in Preparation Example 3; the remaining steps are consistent with Example 2.

[0033] Example 6 The difference between Example 6 and Example 2 is that the silane-modified nano-silica is the silane-modified nano-silica in Preparation Example 4; the remaining steps are consistent with Example 2.

[0034] Example 7 The difference between Example 7 and Example 2 is that the silane-modified nano-silica is the silane-modified nano-silica in Preparation Example 5; the remaining steps are consistent with Example 2.

[0035] Example 8 The difference between Example 8 and Example 5 is that the reaction solution A is prepared as follows: under vacuum conditions, the mixed solution A, 4.5 kg styrene, 0.06 kg molecular weight regulator and 5.5 kg butadiene are mixed, the temperature is raised to 78 ° C, 0.4 kg initiator A is added, the temperature is continued to rise to 86 ° C, heating is stopped, and then the temperature is controlled at 93 ° C, and the reaction is continued for 20 minutes; when the temperature is controlled at the reaction temperature, the mixed solution B, 40.5 kg styrene, 0.54 kg molecular weight regulator and 49.5 kg butadiene are added dropwise to the reaction solution, and the temperature is continuously controlled at 93 ° C, and the reaction is continued; sampling and monitoring are performed during the reaction, and when the sampled solid content reaches 70-75% of the theoretical solid content, the dropwise addition of the mixed solution B is suspended, 0.6 kg dicarboxylic unsaturated carboxylic acid derivative is added, and stirring is performed for 11 minutes, and then the remaining mixed solution B is continued to be added dropwise until the dropwise addition is completed, and the dropwise addition time is controlled at 4 hours to obtain a reaction solution A; wherein the molecular weight regulator is tert-dodecyl mercaptan; and the initiator A is ammonium persulfate; Preparation of colostrum: The reaction liquid A is heated to 96°C, kept warm for 1.5 hours, the pH value of the reaction liquid A is adjusted, and then 0.3 kg of defoaming agent is added for degassing; the VOC value of the reaction liquid A is monitored, and when the VOC value of the reaction liquid A drops below 200 ppm, the reaction liquid A is cooled to below 45°C, and then 0.5 kg of antioxidant is added, and the pH value of the reaction liquid is adjusted again. After the material is filtered, colostrum is obtained; wherein the defoaming agent is polydimethylsiloxane; the antioxidant is dilauryl thiodipropionate emulsion; compounding: the colostrum is mixed with 0.3 kg of catalyst, and then 0.3 kg of initiator is added. B, under the protection of inert gas, heated to 85 ° C for reaction for 2h, then added 11kg plasticizer and 15kg silane-modified nano-silica in Preparation Example 1, stirred until uniformly dispersed, cooled, and finally added 2kg diphenyl phthalate, 2kg carbodiimide, and 3kg adhesive, stirred and mixed evenly, and filtered using a filter membrane with a pore size of 0.2-0.5 microns to obtain carboxylated styrene butadiene latex for thermal paper; wherein the catalyst is tetrabutyl titanate; the initiator B is ammonium persulfate; the plasticizer is diisononyl phthalate; the adhesive is polyvinyl alcohol; and the remaining steps are consistent with Example 5.

[0036] Example 9 The difference between Example 9 and Example 5 is that the reaction solution A is prepared as follows: under vacuum conditions, the mixed solution A, 4.5 kg styrene, 0.06 kg molecular weight regulator and 5.5 kg butadiene are mixed, the temperature is raised to 80°C, 0.4 kg initiator A is added, the temperature is continued to rise to 88°C, heating is stopped, and then the temperature is controlled at 95°C and the reaction is continued for 10 minutes; when the temperature is controlled at the reaction temperature, the mixed solution B, 40.5 kg styrene, 0.54 kg molecular weight regulator and 49.5 kg butadiene are added dropwise to the reaction solution, and the temperature is continuously controlled at 95°C and the reaction is continued; sampling and monitoring are performed during the reaction, and when the sampled solid content reaches 70-75% of the theoretical solid content, the dropwise addition of the mixed solution B is suspended, 0.6 kg dicarboxylic unsaturated carboxylic acid derivative is added, and stirring is performed for 10 minutes, and then the remaining mixed solution B is continued to be added dropwise until the dropwise addition is completed, and the dropwise addition time is controlled at 5 hours to obtain a reaction solution A; wherein the molecular weight regulator is tert-dodecyl mercaptan; and the initiator A is ammonium persulfate; Preparation of colostrum: The reaction liquid A is heated to 98°C, kept warm for 1 hour, the pH value of the reaction liquid A is adjusted, and then 0.3 kg of defoaming agent is added for degassing; the VOC value of the reaction liquid A is monitored, and when the VOC value of the reaction liquid A drops below 200 ppm, the reaction liquid A is cooled to below 45°C, and then 0.5 kg of antioxidant is added, and the pH value of the reaction liquid is adjusted again. After the material is discharged and filtered, colostrum is obtained; wherein the defoaming agent is polydimethylsiloxane; and the antioxidant is dilauryl thiodipropionate emulsion; Compounding: colostrum is mixed with 0.3 kg of catalyst, and then 0.3 kg of initiator B is added. Under the protection of inert gas, the mixture is heated to 90° C. for reaction for 1 h. Then 11 kg of plasticizer and 15 kg of silane-modified nano-silica in Preparation Example 1 are added, stirred until uniformly dispersed, cooled, and finally 2 kg of diphenyl phthalate, 2 kg of carbodiimide, and 3 kg of adhesive are added. The mixture is stirred and mixed uniformly, and filtered using a filter membrane with a pore size of 0.2-0.5 μm to obtain carboxylated styrene butadiene latex for thermal paper; wherein the catalyst is tetrabutyl titanate; the initiator B is ammonium persulfate; the plasticizer is diisononyl phthalate; the adhesive is polyvinyl alcohol; and the remaining steps are consistent with Example 5.

[0037] Comparative Example Comparative Example 1 Comparative Example 1 provides a preparation process of carboxylated styrene-butadiene latex for thermal paper, comprising the following steps: Preparation of mixed solution: 40 kg of deionized water, 0.1 kg of emulsifier, 0.5 kg of dicarboxylic unsaturated carboxylic acid derivative, 0.3 kg of cross-linking monomer, and 1.2 kg of neutralizer were stirred and mixed to obtain mixed solution A; 40 kg of deionized water, 0.9 kg of emulsifier, and 1.2 kg of dicarboxylic unsaturated carboxylic acid derivative were stirred and mixed to obtain mixed solution B; wherein the emulsifier is sodium lauryl sulfate; the dicarboxylic unsaturated carboxylic acid derivative is maleic anhydride; the cross-linking monomer is hydroxyethyl acrylate; and the neutralizer is sodium bicarbonate; Preparation of reaction solution A: under vacuum conditions, mixed solution A, 4 kg styrene, 0.04 kg molecular weight regulator and 5 kg butadiene are mixed, the temperature is raised to 75°C, 0.3 kg initiator A is added, the temperature is continued to rise to 85°C, heating is stopped, and then the temperature is controlled at 92°C for reaction for 30 minutes; when the temperature is controlled, mixed solution B, 36 kg styrene, 0.36 kg molecular weight regulator and 45 kg butadiene are added dropwise to the reaction solution, and the temperature is continuously controlled at 92°C for reaction; sampling and monitoring are performed during the reaction, and when the sampled solid content reaches 70-75% of the theoretical solid content, the dropwise addition of mixed solution B is stopped, 0.3 kg dicarboxylic unsaturated carboxylic acid derivative is added, stirring is performed for 12 minutes, and then the remaining mixed solution B is continued to be added dropwise until the dropwise addition is completed, and the dropwise addition time is controlled at 3 hours to obtain reaction solution A; wherein the molecular weight regulator is tert-dodecyl mercaptan; and initiator A is ammonium persulfate; Preparation of latex: The reaction liquid A is heated to 95°C, kept warm for 2 hours, the pH value of the reaction liquid A is adjusted, and then 0.1 kg of defoaming agent is added for degassing; the VOC value of the reaction liquid A is monitored, and when the VOC value of the reaction liquid A drops below 200 ppm, the reaction liquid A is cooled to below 45°C, and then 0.2 kg of antioxidant is added, and the pH value of the reaction liquid is adjusted again. After the material is discharged and filtered, carboxylated styrene butadiene latex for thermal paper is obtained; wherein the defoaming agent is polydimethylsiloxane; and the antioxidant is dilauryl thiodipropionate emulsion.

[0038] Comparative Example 2 Comparative Example 2 provides a preparation process of carboxylated styrene-butadiene latex for thermal paper, comprising the following steps: Preparation of mixed solution: 40 kg of deionized water, 0.1 kg of emulsifier, 0.5 kg of dicarboxylic unsaturated carboxylic acid derivative, 0.3 kg of cross-linking monomer, and 1.2 kg of neutralizer were stirred and mixed to obtain mixed solution A; 40 kg of deionized water, 0.9 kg of emulsifier, and 1.2 kg of dicarboxylic unsaturated carboxylic acid derivative were stirred and mixed to obtain mixed solution B; wherein the emulsifier is sodium lauryl sulfate; the dicarboxylic unsaturated carboxylic acid derivative is maleic anhydride; the cross-linking monomer is hydroxyethyl acrylate; and the neutralizer is sodium bicarbonate; Preparation of reaction solution A: under vacuum conditions, mixed solution A, 4 kg styrene, 0.04 kg molecular weight regulator and 5 kg butadiene are mixed, the temperature is raised to 75°C, 0.3 kg initiator A is added, the temperature is continued to rise to 85°C, heating is stopped, and then the temperature is controlled at 92°C for reaction for 30 minutes; when the temperature is controlled, mixed solution B, 36 kg styrene, 0.36 kg molecular weight regulator and 45 kg butadiene are added dropwise to the reaction solution, and the temperature is continuously controlled at 92°C for reaction; sampling and monitoring are performed during the reaction, and when the sampled solid content reaches 70-75% of the theoretical solid content, the dropwise addition of mixed solution B is stopped, 0.3 kg dicarboxylic unsaturated carboxylic acid derivative is added, stirring is performed for 12 minutes, and then the remaining mixed solution B is continued to be added dropwise until the dropwise addition is completed, and the dropwise addition time is controlled at 3 hours to obtain reaction solution A; wherein the molecular weight regulator is tert-dodecyl mercaptan; and initiator A is ammonium persulfate; Preparation of colostrum: The reaction liquid A is heated to 95°C, kept warm for 2 hours, the pH value of the reaction liquid A is adjusted, and then 0.1 kg of defoaming agent is added for degassing; the VOC value of the reaction liquid A is monitored, and when the VOC value of the reaction liquid A drops below 200 ppm, the reaction liquid A is cooled to below 45°C, and then 0.2 kg of antioxidant is added, and the pH value of the reaction liquid is adjusted again. After the material is discharged and filtered, colostrum is obtained; wherein the defoaming agent is polydimethylsiloxane; and the antioxidant is dilauryl thiodipropionate emulsion; Compounding: Mix colostrum with 0.2 kg of catalyst, then add 0.2 kg of initiator B, heat to 80 ° C under the protection of inert gas for 3 hours, then add 10 kg of plasticizer and 10 kg of silane-modified nano-silica in Preparation Example 1, stir until uniformly dispersed, cool, and filter with a filter membrane with a pore size of 0.2-0.5 microns to obtain carboxylated styrene butadiene latex for thermal paper; wherein the catalyst is tetrabutyl titanate; initiator B is ammonium persulfate; and the plasticizer is diisononyl phthalate.

[0039] Performance Test Adhesive Strength: The carboxylated styrene butadiene latex in each embodiment and comparative example was tested according to the test method in GB / T 2791-1995T.

[0040] Table 1 Performance test results of carboxylated styrene butadiene latex Combining Example 1 and Comparative Examples 1-2, the bonding strength of the carboxylated styrene butadiene latex in Example 1 is relatively high. It can be seen that when preparing the carboxylated styrene butadiene latex, adding silane-modified nano-silica, initiator B, plasticizer, catalyst, diphenyl phthalate, carbodiimide, and adhesive can further improve the bonding strength of the carboxylated styrene butadiene latex.

[0041] In combination with Examples 1-3, the bonding strength of the carboxylated styrene butadiene latex in Example 2 is the highest. It can be seen that when preparing the carboxylated styrene butadiene latex, the raw material ratio in Example 2 is optimal, so the bonding strength of the obtained carboxylated styrene butadiene latex is higher.

[0042] Combining Example 2 and Example 4-7, the bonding strength of the carboxylated styrene butadiene latex in Example 4-6 is relatively high. It can be seen that when preparing silane-modified nano-silica, the ratio of the spray liquid to the nano-silica is preferably 1:(13-14), and the performance of the silane-modified nano-silica is better.

[0043] Combining Example 5, Example 8 and Example 9, the bonding strength of the carboxylated styrene butadiene latex in Example 8 is the highest. It can be seen that when preparing the carboxylated styrene butadiene latex, the preparation conditions in Example 8 are optimal, so the bonding strength of the carboxylated styrene butadiene latex is higher.

[0044] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A carboxylated styrene-butadiene latex for thermal paper, characterized in that: The raw materials of the carboxylated styrene butadiene latex include the following components in parts by weight: 80-120 parts of deionized water, 50-60 parts of butadiene, 40-50 parts of styrene, 1-10 parts of polar monomers, 3-5 parts of cross-linking monomers, 2-5 parts of dicarboxyl unsaturated carboxylic acid derivatives, 0.6-1 parts of initiator A, 0.4-0.8 parts of molecular weight regulator, 1-3 parts of emulsifier, 1.2-1.6 parts of neutralizer, 0.1-0.5 parts of defoamer, 0.2-0.8 parts of antioxidant, 10-20 parts of silane-modified nano-silica, 0.2-0.4 parts of initiator B, 10-12 parts of plasticizer, 0.2-0.4 parts of catalyst, 1-3 parts of diphenyl phthalate, 1-3 parts of carbodiimide, and 2-4 parts of adhesive.

2. The carboxylated styrene-butadiene latex for thermal paper according to claim 1, characterized in that: The preparation method of the silane-modified nano-silicon dioxide comprises the following steps: γ-aminopropyltriethoxysilane, ethanol and water are stirred and mixed to obtain a spraying liquid; The nano-silicon dioxide is stirred, and during the stirring process, a spraying liquid is sprayed into the nano-silicon dioxide. After the spraying is completed, the nano-silicon dioxide is stirred and dried to obtain silane-modified nano-silicon dioxide.

3. The carboxylated styrene-butadiene latex for thermal paper according to claim 2, characterized in that: The weight ratio of the spraying liquid to the nano silicon dioxide is 1:(13-14).

4. The carboxylated styrene-butadiene latex for thermal paper according to claim 1, characterized in that: The initiator B includes ammonium persulfate.

5. The carboxylated styrene-butadiene latex for thermal paper according to claim 1, characterized in that: The plasticizer includes one or more of diisononyl phthalate, di-2-ethylhexyl phthalate, and dioctyl phthalate.

6. The carboxylated styrene-butadiene latex for thermal paper according to claim 1, characterized in that: The catalyst includes one of tetrabutyl titanate and aluminum triacetylacetonate.

7. The carboxylated styrene-butadiene latex for thermal paper according to claim 1, characterized in that: The binder includes one or more of polyvinyl alcohol, hydroxyethyl cellulose and starch.

8. A process for preparing carboxylated styrene-butadiene latex for thermal paper according to any one of claims 1 to 7, characterized in that: The following steps are involved: Preparation of mixed solution: stir and mix part of deionized water, part of emulsifier, part of dicarboxylic unsaturated carboxylic acid derivative, part of cross-linking monomer and neutralizer to obtain mixed solution A; stir and mix the remaining deionized water, the remaining emulsifier and part of dicarboxylic unsaturated carboxylic acid derivative to obtain mixed solution B; Preparation of reaction liquid A: under vacuum conditions, mixed liquid A, part of styrene, part of molecular weight regulator and part of butadiene are mixed, heated to 75-80°C, part of initiator A is added, the temperature is continued to be raised to 85-88°C, heating is stopped, and then the temperature is controlled at 92-95°C, and the reaction is carried out for 10-30 minutes; while the temperature is controlled, mixed liquid B, the remaining styrene, the remaining molecular weight regulator and the remaining butadiene are added dropwise to the reaction liquid, and the temperature is continuously controlled at 92-95°C, and the reaction is continued; sampling and monitoring are performed during the reaction, and when the solid content of the sample reaches 70-75% of the theoretical solid content, the addition of mixed liquid B is stopped, the remaining dicarboxylic unsaturated carboxylic acid derivative is added, stirring is carried out for 10-12 minutes, and then the remaining mixed liquid B is continued to be added dropwise until the addition is completed, and the addition time is controlled at 3-5 hours to obtain reaction liquid A; Preparation of colostrum: The reaction liquid A is heated to 95-98°C, kept warm for 1-2 hours, the pH value of the reaction liquid is adjusted, and then a defoaming agent is added for degassing; the VOC value of the reaction liquid A is monitored, and when the VOC value of the reaction liquid A drops below 200ppm, the reaction liquid A is cooled to below 45°C, and then an antioxidant is added, and the pH value of the reaction liquid is adjusted again. After the material is filtered, colostrum is obtained; Compounding: Mix colostrum with the catalyst, then add initiator B, heat the reaction under the protection of inert gas, then add plasticizer and silane-modified nano-silica, stir until evenly dispersed, cool, and finally add diphenyl phthalate, carbodiimide, and adhesive, stir and mix evenly, filter, and obtain carboxylated styrene butadiene latex for thermal paper.

9. The process for preparing carboxylated styrene-butadiene latex for thermal paper according to claim 8, characterized in that: In the compounding step, the heating temperature is 80-90° C. and the reaction time is 1-3 hours.

10. The process for preparing carboxylated styrene-butadiene latex for thermal paper according to claim 8, characterized in that: In the compounding step, filtering is performed using a filter membrane with a pore size of 0.2-0.5 microns.

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