Preparation method of high-water-resistance carboxylic butadiene-styrene latex

Abstract

The invention relates to the technical field of emulsion polymerization preparation, and discloses a preparation method of high-water-resistance carboxylic butadiene-styrene latex. The preparation method comprises the following steps: S1, mixing waterborne polyurethane resin, styrene, butadiene, acrylic acid, unsaturated carboxylic acid and N-butoxymethacrylamide to obtain a monomer stock solution; and S2, stirring and mixing the allyl polyalkyl alcohol sulfate ammonium salt and lauryl sodium sulfate to obtain the emulsion. And S3, obtaining an initiation solution with the mass concentration of 0.3%. And S4, mixing the monomer stock solution and the emulsion, and carrying out polymerization reaction under the action of the initiation solution to obtain the latex. And S5, curing for 1 hour. And S6, adjusting the viscosity and pH of the latex. And S7, filtering and discharging. The high-water-resistance carboxylic butadiene-styrene latex can be prepared, good adhesion can be kept in a humid environment, the latex is not prone to falling off in the application process and high in use stability, no organic solvent is contained in the whole preparation process, no harmful gas such as formaldehyde is released, and the technology is environmentally friendly and does not pollute the environment.

Description

Technical Field

[0001] The present invention relates to the technical field of emulsion polymerization preparation, in particular to a preparation method of a highly water-resistant carboxylated styrene-butadiene latex, and also relates to a highly water-resistant carboxylated styrene-butadiene latex prepared by using the said preparation method. Background Art

[0002] Carboxylated styrene-butadiene latex is a material widely used in fields such as coatings, coating printing adhesives, environmentally friendly flocking adhesives, latex paints, fabric coatings, leather finishing agents, and paper. It is polymerized from monomers such as butadiene and styrene. By introducing carboxyl groups, the latex has good adhesion and water resistance. Water resistance is one of the important properties of carboxylated styrene-butadiene latex, which determines the service life and stability of the latex. In a humid environment, if the water resistance of carboxylated styrene-butadiene latex is poor, it will lead to a decrease in adhesion, performance attenuation, and even falling off and failure. Therefore, improving the water resistance of carboxylated styrene-butadiene latex is of great significance for expanding its application fields, improving product quality, and meeting more demanding use environments.

[0003] Currently, the methods for preparing water-resistant carboxylated styrene-butadiene latex mainly include chemical modification, physical blending, etc. Although these methods improve the water resistance of the latex to a certain extent, they have problems such as poor stability and high cost, and it is difficult to meet the requirements of large-scale production and application. Therefore, developing an efficient and low-cost preparation method is of great significance for promoting the development of carboxylated styrene-butadiene latex. Summary of the Invention

[0004] In view of the above-mentioned disadvantages of the prior art, the purpose of the present invention is to provide a preparation method of a highly water-resistant carboxylated styrene-butadiene latex to obtain a highly water-resistant carboxylated styrene-butadiene latex with high stability, good adhesion, and not easy to fall off.

[0005] A preparation method of a highly water-resistant carboxylated styrene-butadiene latex, which comprises the following steps: S1 Take waterborne polyurethane resin, styrene, butadiene, acrylic acid, unsaturated carboxylic acid, and N-butoxymethylacrylamide and mix them to obtain a monomer stock solution; S2 Take allyl polyalkyl alcohol sulfate ammonium salt and sodium dodecyl sulfate and stir and mix them to obtain an emulsion; S3 Dilute the initiator with deionized water to obtain an initiator solution with a mass concentration of 0.3%; S4 Mix the monomer stock solution and the emulsion, and carry out a polymerization reaction under the action of the initiator solution to obtain a latex; S5 The latex is cured at a temperature of 95 - 100 °C for 1 h, and the polymerization reaction is completed; S6 Add sodium hydroxide and the remaining deionized water to adjust the viscosity and pH of the latex; S7 Filter and discharge to obtain a highly water-resistant carboxylated styrene-butadiene latex.

[0006] As a further improvement of the above solution, in the monomer stock solution, the ratio of waterborne polyurethane resin, styrene, butadiene, acrylic acid, unsaturated carboxylic acid, and N-butoxymethylacrylamide is 5-20:12-55:10-42:1-8:1:0.5-2.5. In the present invention, waterborne polyurethane resin with good environmental protection is used as the polymerization monomer, and deionized water is used as the dispersion medium for emulsion polymerization. The waterborne polyurethane resin has the advantages of being non-flammable and having a small odor. It provides flexible chain segments and undergoes a free radical copolymerization reaction with active monomers (styrene, butadiene, acrylic acid, unsaturated carboxylic acid), thereby improving the waterproof property of the latex. N-butoxymethylacrylamide is added to improve the water resistance and solvent resistance of the prepared latex. The entire preparation process does not contain organic solvents, and the added N-butoxymethylacrylamide, as a crosslinking monomer, has the characteristic of being extremely easy to polymerize with acrylic monomers. The crosslinking temperature is low and no harmful gases such as formaldehyde are released during crosslinking, making the preparation process environmentally friendly and non-polluting to the environment.

[0007] As a further improvement of the above solution, the allyl polyalkyl alcohol sulfate ammonium salt and sodium dodecyl sulfate are stirred and mixed at a ratio of 1-3:1 at 25-30 °C and 400-600 r / min for 20-30 min to obtain an emulsion with a mass concentration of 0.5%. In the present invention, allyl polyalkyl alcohol sulfate ammonium salt and sodium dodecyl sulfate are added as emulsifiers to reduce the interfacial tension, causing the monomers to disperse into fine droplets, thereby making the mixed solution form a stable emulsion system. At the same time, the allyl polyalkyl alcohol sulfate ammonium salt enables the emulsion to better penetrate into the substrate, improving the adhesion and forming a relatively firm coating.

[0008] As a further improvement of the above solution, the initiator uses any one of ammonium persulfate and potassium persulfate.

[0009] As a further improvement of the above solution, the polymerization reaction is carried out in a reaction kettle, and the temperature of the polymerization reaction is 84-86 °C, and the reaction time is 4-5 h.

[0010] As a further improvement of the above solution, before adding the materials into the reaction kettle, the reaction kettle is evacuated and filled with nitrogen, and this is repeated three times to completely evacuate the oxygen in the reaction kettle.

[0011] As a further improvement of the above solution, the method for obtaining the latex by the polymerization reaction is specifically operated as follows: S41 Take 10% of the emulsion and 10% of the monomer stock solution and add them into the reaction kettle. After stirring and mixing for 10 min, steam is introduced into the reaction kettle and the temperature in the kettle is raised to 70 °C; Put 20% of the initiator solution into the reaction kettle and mix and react at a temperature of 84 - 86°C for 20 - 30 min; Maintain the temperature at 84 - 86°C and continue to dropwise add the remaining emulsion, monomer stock solution and initiator solution. The dropping time is 4 h, and stop dropping when the conversion rate reaches 99.5%.

[0012] As a further improvement of the above solution, add sodium hydroxide and the remaining deionized water and stir and mix to obtain a sodium hydroxide solution with a mass concentration of 12.5%. Use the sodium hydroxide solution to adjust the viscosity and pH of the latex. In the present invention, by adding the sodium hydroxide solution to adjust the pH value of the latex, the latex is transformed into a weak acid to improve its water solubility and adhesion.

[0013] As a further improvement of the above solution, the solid content of the high water - resistant carboxylated styrene - butadiene latex is 49% - 50%, the viscosity is 160 - 200 cp, and the pH is 6 - 8.

[0014] As a further improvement of the above solution, the weight parts composition of the high water - resistant carboxylated styrene - butadiene latex is as follows: 8 - 12 parts of water - borne polyurethane resin, 15 - 20 parts of butadiene, 25 - 30 parts of styrene, 1 - 3 parts of acrylic acid, 1 - 1.5 parts of N - butoxymethylacrylamide, 0.5 - 1.5 parts of unsaturated carboxylic acid, 0.3 - 0.8 parts of allyl polyalkyl alcohol sulfate ammonium salt, 0.2 - 0.5 parts of sodium dodecyl sulfate, 0.8 - 1.2 parts of initiator, 5 - 9 parts of sodium hydroxide, 40 - 50 parts of deionized water.

[0015] As a further improvement of the above solution, the weight parts composition of the high water - resistant carboxylated styrene - butadiene latex is as follows: 11 parts of water - borne polyurethane resin, 20 parts of butadiene, 25 parts of styrene, 1.5 parts of acrylic acid, 1.5 parts of N - butoxymethylacrylamide, 1.5 parts of unsaturated carboxylic acid, 0.5 parts of allyl polyalkyl alcohol sulfate ammonium salt, 0.2 parts of sodium dodecyl sulfate, 0.8 parts of initiator, 8 parts of sodium hydroxide, 41 parts of deionized water. In the present invention, adding water - borne polyurethane resin, the hydrophilic groups in the water - borne polyurethane resin form hydrogen bonds with water molecules, increasing the solubility and stability of the polymer in water. And the water - borne polyurethane resin can form a dense coating film structure during the film - forming process, reducing the possibility of water penetration and diffusion. The hydrophobic groups in the molecular structure can also enhance the water resistance of the coating film. In addition, the active groups in the water - borne polyurethane resin cross - link with other compounds to form a three - dimensional network structure, significantly improving the water resistance and mechanical strength of the coating film, thereby improving the water resistance and comprehensive performance of the prepared styrene - butadiene latex product.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: a highly water-resistant carboxylated styrene-butadiene latex can be prepared, which can maintain good adhesion even in a humid environment, is not easy to fall off during application, has high use stability, the entire preparation process does not contain organic solvents, and no harmful gases such as formaldehyde are released. The process is environmentally friendly and does not pollute the environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The figure shows a flowchart of a method for preparing a highly water-resistant carboxylated styrene-butadiene latex provided by the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0018] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with embodiments. The additional aspects and advantages of the present invention will be partially given in the following description, partially become obvious from the following description, or be understood through the practice of the present invention. It should be understood that the following description is only used to explain the present invention and is not used to limit the present invention.

[0019] As used herein, the terms "comprising", "including", "containing" or any other variation thereof are intended to cover non-exclusive inclusion. For example, a composition, step, method, article or device containing the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such composition, step, method, article or device.

[0020] When an equivalent, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper preferred values and lower preferred values, it should be understood that all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value are specifically disclosed, regardless of whether the range is separately disclosed. For example, when the range "1 to 5" is disclosed, the described range should be interpreted as including the ranges "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described herein, unless otherwise stated, the range is intended to include its end values and all integers and fractions within the range.

[0021] The following will give a detailed description of the specific embodiments of the present invention. Example 1

[0022] This example provides a method for preparing a highly water-resistant carboxylated styrene-butadiene latex, which includes the following steps: S1 Take 8 parts of waterborne polyurethane resin, 25 parts of styrene, 20 parts of butadiene, 3 parts of acrylic acid, 0.5 part of unsaturated carboxylic acid and 1 part of N-butoxymethylacrylamide and mix them to obtain a monomer stock solution. In this example, waterborne polyurethane resin with good environmental protection is used as the polymerization monomer, and deionized water is used as the dispersion medium for emulsion polymerization. The waterborne polyurethane resin has the advantages of being non-flammable and having a small odor. It provides flexible chain segments and undergoes a free radical copolymerization reaction with active monomers (styrene, butadiene, acrylic acid, unsaturated carboxylic acid), thereby improving the waterproof property of the latex. Adding N-butoxymethylacrylamide can improve the water resistance and solvent resistance of the obtained latex. The entire preparation process does not contain organic solvents, and the added N-butoxymethylacrylamide, as a crosslinking monomer, has the characteristic of being extremely easy to polymerize with acrylic monomers. The crosslinking temperature is low and no harmful gases such as formaldehyde are released during crosslinking, making the preparation process environmentally friendly and non-polluting to the environment.

[0023] S2 Take 0.4 part of allyl polyalkyl alcohol sulfate ammonium salt and 0.3 part of sodium dodecyl sulfate, and stir and mix them at 25 °C and 600 r / min for 30 min to obtain an emulsion with a mass concentration of 0.5%. In this example, allyl polyalkyl alcohol sulfate ammonium salt and sodium dodecyl sulfate are added as emulsifiers to reduce the interfacial tension, causing the monomers to disperse into fine droplets, thereby making the mixed solution form a stable emulsion system. At the same time, allyl polyalkyl alcohol sulfate ammonium salt enables the emulsion to better penetrate into the substrate, improving the adhesion and forming a relatively firm coating.

[0024] S3 Dilute 0.8 part of ammonium persulfate with deionized water to obtain an initiator solution with a mass concentration of 0.3%.

[0025] S4 Mix the monomer stock solution and the emulsion, and carry out a polymerization reaction under the action of the initiator solution to obtain a latex.

[0026] The polymerization reaction is carried out in a reaction kettle, and the temperature of the polymerization reaction is 85 °C and the reaction time is 4.5 h. Before adding the materials into the reaction kettle, first evacuate the reaction kettle and fill it with nitrogen, and repeat three times to completely evacuate the oxygen in the reaction kettle.

[0027] The method for obtaining the latex by the polymerization reaction is specifically operated as follows: S41 Take 10% of the emulsion and 10% of the monomer stock solution and add them into the reaction kettle. After stirring and mixing for 10 min, introduce steam into the reaction kettle and raise the temperature in the kettle to 70 °C.

[0028] S42 Put 20% of the initiator solution into the reaction kettle and carry out a mixing reaction at a temperature of 85 °C for 20 min.

[0029] Maintain the temperature at 85 °C for S43, and continue to dropwise add the remaining emulsion, monomer stock solution, and initiator solution. The dropping time is 4 h, and stop dropping when the conversion rate reaches 99.5%.

[0030] For S5, cure the latex at 98 °C for 1 h to complete the polymerization reaction.

[0031] For S6, add 8 parts of sodium hydroxide and the remaining deionized water, stir and mix to obtain a sodium hydroxide solution with a mass concentration of 12.5%. Use the sodium hydroxide solution to adjust the viscosity and pH of the latex. In this example, by adding the sodium hydroxide solution to adjust the pH value of the latex, the latex is transformed into a weak acid to improve its water solubility and increase the adhesion.

[0032] For S7, filter and discharge to obtain a high water-resistant carboxylated styrene-butadiene latex.

[0033] Through the preparation method of this example, the high water-resistant carboxylated styrene-butadiene latex produced has the following composition in parts by weight: 8 parts of waterborne polyurethane resin, 20 parts of butadiene, 25 parts of styrene, 3 parts of acrylic acid, 1 part of N-butoxymethylacrylamide, 0.5 part of unsaturated carboxylic acid, 0.4 part of allyl polyalkyl alcohol sulfate ammonium salt, 0.3 part of sodium dodecyl sulfate, 0.8 part of ammonium persulfate, 8 parts of sodium hydroxide, and 41 parts of deionized water. The solid content of the high water-resistant carboxylated styrene-butadiene latex is 49.5%, the viscosity is 180 cp, and the pH is 6.5. Example 2

[0034] This example provides a preparation method of a high water-resistant carboxylated styrene-butadiene latex, which includes the following steps: For S1, take 10 parts of waterborne polyurethane resin, 25 parts of styrene, 20 parts of butadiene, 1.5 parts of acrylic acid, 1.5 parts of unsaturated carboxylic acid, and 1.5 parts of N-butoxymethylacrylamide and mix to obtain a monomer stock solution. In this example, waterborne polyurethane resin with good environmental protection is used as a polymerization monomer, and deionized water is used as a dispersion medium for emulsion polymerization. The waterborne polyurethane resin has the advantages of being non-flammable and having a small odor. It provides flexible chain segments and undergoes a free radical copolymerization reaction with active monomers (styrene, butadiene, acrylic acid, unsaturated carboxylic acid), thereby improving the waterproof property of the latex. Adding N-butoxymethylacrylamide can improve the water resistance and solvent resistance of the obtained latex. The entire preparation process does not contain organic solvents, and the added N-butoxymethylacrylamide, as a crosslinking monomer, has the characteristic of being extremely easy to polymerize with acrylic monomers, with a low crosslinking temperature and no harmful gases such as formaldehyde released during crosslinking, making the preparation process environmentally friendly and non-polluting to the environment.

[0035] Take 0.4 parts of allyl polyalkyl alcohol sulfate ammonium salt and 0.3 parts of sodium dodecyl sulfate, and stir and mix them for 30 minutes at 25 °C and 600 r / min to obtain an emulsion with a mass concentration of 0.5%. In this example, allyl polyalkyl alcohol sulfate ammonium salt and sodium dodecyl sulfate are added as emulsifiers, which play a role in reducing the interfacial tension, causing the monomers to disperse into fine droplets, and thus enabling the mixture to form a stable emulsion system. At the same time, allyl polyalkyl alcohol sulfate ammonium salt enables the emulsion to better penetrate into the substrate, improving the adhesion and forming a relatively firm coating.

[0036] Dilute 0.8 parts of ammonium persulfate with deionized water to obtain an initiator solution with a mass concentration of 0.3%.

[0037] Mix the monomer stock solution and the emulsion, and carry out a polymerization reaction under the action of the initiator solution to obtain latex.

[0038] The polymerization reaction is carried out in a reaction kettle, and the temperature of the polymerization reaction is 85 °C and the reaction time is 4.5 h. Before adding the materials into the reaction kettle, first evacuate the reaction kettle and fill it with nitrogen, and repeat three times to completely evacuate the oxygen in the reaction kettle.

[0039] The method for obtaining latex by the polymerization reaction is specifically operated as follows: Take 10% of the emulsion and 10% of the monomer stock solution and add them into the reaction kettle. After stirring and mixing for 10 minutes, introduce steam into the reaction kettle and raise the temperature in the kettle to 70 °C.

[0040] Take 20% of the initiator solution and put it into the reaction kettle, and carry out a mixing reaction at a temperature of 85 °C for 20 minutes.

[0041] Maintain the temperature of 85 °C, continue to dropwise add the remaining emulsion, monomer stock solution and initiator solution. The dropping time is 4 h, and stop dropping when the conversion rate reaches 99.5%.

[0042] The latex is cured at a temperature of 98 °C for 1 h, and the polymerization reaction is completed.

[0043] Add 8 parts of sodium hydroxide and the remaining deionized water, stir and mix them to obtain a sodium hydroxide solution with a mass concentration of 12.5%. Use the sodium hydroxide solution to adjust the viscosity and pH of the latex. In this example, by adding the sodium hydroxide solution to adjust the pH value of the latex, the latex is converted into a weak acid to improve its water solubility and adhesion.

[0044] Filter and discharge to obtain high water-resistant carboxylated styrene-butadiene latex.

[0045] By the preparation method of this embodiment, the high water-resistant carboxylated styrene-butadiene latex obtained has the following composition in parts by weight: 10 parts of waterborne polyurethane resin, 20 parts of butadiene, 25 parts of styrene, 1.5 parts of acrylic acid, 1.5 parts of N-butoxymethylacrylamide, 1.5 parts of unsaturated carboxylic acid, 0.4 part of allyl polyalkyl alcohol sulfate ammonium salt, 0.3 part of sodium dodecyl sulfate, 0.8 part of ammonium persulfate, 8 parts of 12.5% sodium hydroxide, and 41 parts of deionized water. The solid content of the high water-resistant carboxylated styrene-butadiene latex is 49.5%, the viscosity is 176 cp, and the pH is 6.5. Example 3

[0046] This embodiment provides a preparation method of a high water-resistant carboxylated styrene-butadiene latex, which includes the following steps: S1 Take 11 parts of waterborne polyurethane resin, 25 parts of styrene, 20 parts of butadiene, 1.5 parts of acrylic acid, 1.5 parts of unsaturated carboxylic acid, and 1.5 parts of N-butoxymethylacrylamide and mix them to obtain a monomer stock solution. In this embodiment, waterborne polyurethane resin with good environmental protection is used as a polymerization monomer, and deionized water is used as a dispersion medium for emulsion polymerization. The waterborne polyurethane resin has the advantages of being non-flammable and having a small odor. It provides flexible chain segments and undergoes a free radical copolymerization reaction with active monomers (styrene, butadiene, acrylic acid, unsaturated carboxylic acid), thereby improving the waterproof property of the latex. Adding N-butoxymethylacrylamide can improve the water resistance and solvent resistance of the obtained latex. The entire preparation process does not contain organic solvents, and the added N-butoxymethylacrylamide, as a crosslinking monomer, has the characteristic of being extremely easy to polymerize with acrylic monomers, with a low crosslinking temperature and no harmful gases such as formaldehyde released during crosslinking, making the preparation process environmentally friendly and non-polluting.

[0047] S2 Take 0.5 part of allyl polyalkyl alcohol sulfate ammonium salt and 0.2 part of sodium dodecyl sulfate, stir and mix them at 25 °C and 600 r / min for 30 min to obtain an emulsion with a mass concentration of 0.5%. In this embodiment, allyl polyalkyl alcohol sulfate ammonium salt and sodium dodecyl sulfate are added as emulsifiers, which play a role in reducing the interfacial tension, enabling the monomers to be dispersed into fine droplets, and thus making the mixed solution form a stable emulsion system. At the same time, allyl polyalkyl alcohol sulfate ammonium salt enables the emulsion to better penetrate into the substrate, improving the adhesion and forming a relatively firm coating.

[0048] S3 Dilute 0.8 part of ammonium persulfate with deionized water to obtain an initiator solution with a mass concentration of 0.3%.

[0049] S4 Mix the monomer stock solution and the emulsion, and carry out a polymerization reaction under the action of the initiator solution to obtain a latex.

[0050] The polymerization reaction is carried out in a reaction kettle, and the temperature of the polymerization reaction is 85 °C, and the reaction time is 4.5 h. Before adding the materials into the reaction kettle, the reaction kettle is evacuated and filled with nitrogen, and this is repeated three times to completely evacuate the oxygen in the reaction kettle.

[0051] The method for obtaining the latex by the polymerization reaction is specifically operated as follows: S41 Take 10% of the emulsion and 10% of the monomer stock solution and add them into the reaction kettle. After stirring and mixing for 10 min, steam is introduced into the reaction kettle and the temperature in the kettle is raised to 70 °C.

[0052] S42 Take 20% of the initiator solution and put it into the reaction kettle, and mix and react at a temperature of 85 °C for 20 min.

[0053] S43 Keep the temperature at 85 °C, and continue to dropwise add the remaining emulsion, monomer stock solution and initiator solution. The dropping time is 4 h, and when the conversion rate reaches 99.5%, the dropping is stopped.

[0054] S5 The latex is cured at a temperature of 98 °C for 1 h, and the polymerization reaction is completed.

[0055] S6 Add 8 parts of sodium hydroxide and the remaining deionized water and stir and mix to obtain a sodium hydroxide solution with a mass concentration of 12.5%. Use the sodium hydroxide solution to adjust the viscosity and pH of the latex. In this example, the pH value of the latex is adjusted by adding the sodium hydroxide solution to make the latex turn into weak acidity to improve its water solubility and increase the adhesion.

[0056] S7 Filter and discharge to obtain a highly water-resistant carboxylated styrene-butadiene latex.

[0057] By the preparation method of this example, the highly water-resistant carboxylated styrene-butadiene latex produced has the following composition by weight: 11 parts of waterborne polyurethane resin, 20 parts of butadiene, 25 parts of styrene, 1.5 parts of acrylic acid, 1.5 parts of N-butoxymethylacrylamide, 1.5 parts of unsaturated carboxylic acid, 0.5 part of allyl polyalkyl alcohol sulfate ammonium salt, 0.2 part of sodium dodecyl sulfate, 0.8 part of ammonium persulfate, 8 parts of sodium hydroxide, and 41 parts of deionized water. The solid content of the highly water-resistant carboxylated styrene-butadiene latex is 49.5%, the viscosity is 178 cp, and the pH is 6.5. Example 4

[0058] This example provides a preparation method of a highly water-resistant carboxylated styrene-butadiene latex, which includes the following steps: S1 Take 10 parts of waterborne polyurethane resin, 25 parts of styrene, 20 parts of butadiene, 1 part of acrylic acid, 1.5 parts of unsaturated carboxylic acid and 1 part of N-butoxymethylacrylamide and mix them to obtain a monomer stock solution. In this example, waterborne polyurethane resin with good environmental protection is used as the polymerization monomer, and deionized water is used as the dispersion medium for emulsion polymerization. The waterborne polyurethane resin has the advantages of being non-flammable and having a small odor. It provides flexible chain segments and undergoes a free radical copolymerization reaction with active monomers (styrene, butadiene, acrylic acid, unsaturated carboxylic acid), thereby improving the waterproof property of the latex. Adding N-butoxymethylacrylamide can improve the water resistance and solvent resistance of the obtained latex. The entire preparation process does not contain organic solvents, and the added N-butoxymethylacrylamide, as a crosslinking monomer, has the characteristic of being extremely easy to polymerize with acrylic monomers. The crosslinking temperature is low and no harmful gases such as formaldehyde are released during crosslinking, making the preparation process environmentally friendly and non-polluting to the environment.

[0059] S2 Take 0.4 parts of allyl polyalkyl alcohol sulfate ammonium salt and 0.3 parts of sodium dodecyl sulfate, and stir and mix them at 25 °C and 600 r / min for 30 min to obtain an emulsion with a mass concentration of 0.5%. In this example, allyl polyalkyl alcohol sulfate ammonium salt and sodium dodecyl sulfate are added as emulsifiers, which play a role in reducing the interfacial tension, enabling the monomers to disperse into fine droplets, and thus making the mixture form a stable emulsion system. At the same time, allyl polyalkyl alcohol sulfate ammonium salt enables the emulsion to better penetrate into the substrate, improving the adhesion and forming a relatively firm coating.

[0060] S3 Dilute 0.8 parts of ammonium persulfate with deionized water to obtain an initiator solution with a mass concentration of 0.3%.

[0061] S4 Mix the monomer stock solution and the emulsion, and carry out a polymerization reaction under the action of the initiator solution to obtain a latex.

[0062] The polymerization reaction is carried out in a reaction kettle, and the temperature of the polymerization reaction is 85 °C and the reaction time is 4.5 h. Before adding materials into the reaction kettle, first evacuate the reaction kettle and fill it with nitrogen, and repeat this three times to completely evacuate the oxygen in the reaction kettle.

[0063] The method for obtaining the latex by the polymerization reaction is specifically operated as follows: S41 Take 10% of the emulsion and 10% of the monomer stock solution and add them into the reaction kettle. After stirring and mixing for 10 min, introduce steam into the reaction kettle and raise the temperature in the kettle to 70 °C.

[0064] S42 Take 20% of the initiator solution and put it into the reaction kettle, and carry out a mixing reaction at a temperature of 85 °C for 20 min.

[0065] Maintain the temperature at 85 °C for S43, and continue to dropwise add the remaining emulsion, monomer stock solution, and initiator solution. The dropping time is 4 h, and stop dropping when the conversion rate reaches 99.5%.

[0066] For S5, cure the latex at 98 °C for 1 h, and the polymerization reaction is completed.

[0067] For S6, add 8 parts of sodium hydroxide and the remaining deionized water, stir and mix to obtain a sodium hydroxide solution with a mass concentration of 12.5%. Use the sodium hydroxide solution to adjust the viscosity and pH of the latex. In this example, by adding the sodium hydroxide solution to adjust the pH value of the latex, the latex is transformed into a weak acid to improve its water solubility and increase the adhesion.

[0068] For S7, filter and discharge to obtain a high water-resistant carboxylated styrene-butadiene latex.

[0069] By the preparation method of this example, the high water-resistant carboxylated styrene-butadiene latex produced has the following composition in parts by weight: 10 parts of waterborne polyurethane resin, 20 parts of butadiene, 25 parts of styrene, 1 part of acrylic acid, 1.5 parts of N-butoxymethylacrylamide, 1 part of unsaturated carboxylic acid, 0.4 part of allyl polyalkyl alcohol sulfate ammonium salt, 0.3 part of sodium dodecyl sulfate, 0.8 part of ammonium persulfate, 8 parts of sodium hydroxide, and 41 parts of deionized water. The solid content of the high water-resistant carboxylated styrene-butadiene latex is 49.5%, the viscosity is 181 cp, and the pH is 6.5.

[0070] Below, a commercially available carboxylated styrene-butadiene latex is used as a comparative example, and the water resistance of the high water-resistant carboxylated styrene-butadiene latexes of Examples 1-4 is tested. The specific test process will not be elaborated, and the test results are as follows: The carboxylated styrene-butadiene latex of the comparative example does not penetrate in 2 h, and the high water-resistant carboxylated styrene-butadiene latexes of Examples 1-4 do not penetrate for more than 3 h. The above results prove that the preparation method of the present invention can produce a high water-resistant carboxylated styrene-butadiene latex.

[0071] The above examples are only the preferred embodiments of the present invention. Any simple modification, modification, and alternative change made to the above examples based on the technical essence of the present invention all fall within the scope of the technical solution of the present invention.

Claims

1. A preparation method of a highly water-resistant carboxylated styrene-butadiene latex, characterized in that, It includes the following steps: S1: Take aqueous polyurethane resin, styrene, butadiene, acrylic acid, unsaturated carboxylic acid, and N-butoxymethylacrylamide and mix them to obtain a monomer stock solution; S2: Take allyl polyalkyl alcohol sulfate ammonium salt and sodium dodecyl sulfate, stir and mix them to obtain an emulsion; S3: Dilute the initiator with deionized water to obtain an initiator solution with a mass concentration of 0.3%; S4: Mix the monomer stock solution and the emulsion, and carry out a polymerization reaction under the action of the initiator solution to obtain latex; S5: Cure the latex at a temperature of 95 - 100 °C for 1 h, and the polymerization reaction is completed; S6: Add sodium hydroxide and the remaining deionized water to adjust the viscosity and pH of the latex; S7: Filter and discharge to obtain a highly water-resistant carboxylated styrene-butadiene latex.

2. The preparation method of a highly water-resistant carboxylated styrene-butadiene latex according to claim 1, characterized in that, In the monomer stock solution, the ratio of aqueous polyurethane resin, styrene, butadiene, acrylic acid, unsaturated carboxylic acid, and N-butoxymethylacrylamide is 5 - 20:12 - 55:10 - 42:1 - 8:1:0.5 - 2.

5.

3. The preparation method of a highly water-resistant carboxylated styrene-butadiene latex according to claim 1, characterized in that, The allyl polyalkyl alcohol sulfate ammonium salt and sodium dodecyl sulfate are stirred and mixed at a ratio of 1 - 3:1 under the conditions of 25 - 30 °C and 400 - 600 r / min for 20 - 30 min to obtain an emulsion with a mass concentration of 0.5%.

4. The preparation method of a highly water-resistant carboxylated styrene-butadiene latex according to claim 1, characterized in that, The initiator uses any one of ammonium persulfate and potassium persulfate.

5. The preparation method of a highly water-resistant carboxylated styrene-butadiene latex according to claim 1, characterized in that, The polymerization reaction is carried out in a reaction kettle, and the temperature of the polymerization reaction is 84 - 86 °C, and the reaction time is 4 - 5 h.

6. The preparation method of a highly water-resistant carboxylated styrene-butadiene latex according to claim 5, characterized in that, Before adding materials to the reaction kettle, first evacuate the reaction kettle and fill it with nitrogen, and repeat three times to completely evacuate the oxygen in the reaction kettle.

7. The preparation method of a highly water-resistant carboxylated styrene-butadiene latex according to claim 6, characterized in that, The method for obtaining latex by the polymerization reaction is specifically operated as follows: S41: Take 10% of the emulsion and 10% of the monomer stock solution and add them to the reaction kettle, stir and mix for 10 min, then introduce steam into the reaction kettle and raise the temperature in the kettle to 70 °C; S42: Put 20% of the initiator solution into the reaction kettle and carry out a mixing reaction at a temperature of 84 - 86 °C for 20 - 30 min; S43: Keep the temperature at 84 - 86 °C, continue to dropwise add the remaining emulsion, monomer stock solution, and initiator solution, and the dropping time is 4 h. Stop dropping when the conversion rate reaches 99.5%.

8. The preparation method of a highly water-resistant carboxylated styrene-butadiene latex according to claim 1, characterized in that, Add sodium hydroxide and the remaining deionized water, stir and mix to obtain a sodium hydroxide solution with a mass concentration of 12.5%, and use the sodium hydroxide solution to adjust the viscosity and pH of the latex; The solid content of the highly water-resistant carboxylated styrene-butadiene latex is 49% - 50%, the viscosity is 160 - 200 cp, and the pH is 6 - 8.

9. The preparation method of a highly water-resistant carboxylated styrene-butadiene latex according to claim 8, characterized in that, The weight composition of the highly water-resistant carboxylated styrene-butadiene latex is as follows: 8 - 12 parts of aqueous polyurethane resin, 15 - 20 parts of butadiene, 25 - 30 parts of styrene, 1 - 3 parts of acrylic acid, 1 - 1.5 parts of N-butoxymethylacrylamide, 0.5 - 1.5 parts of unsaturated carboxylic acid, 0.3 - 0.8 parts of allyl polyalkyl alcohol sulfate ammonium salt, 0.2 - 0.5 parts of sodium dodecyl sulfate, 0.8 - 1.2 parts of initiator, 5 - 9 parts of sodium hydroxide, and 40 - 50 parts of deionized water.

10. The preparation method of a highly water-resistant carboxylated styrene-butadiene latex according to claim 9, characterized in that, The weight parts composition of the high water-resistant carboxylated styrene-butadiene latex is as follows: 11 parts of waterborne polyurethane resin, 20 parts of butadiene, 25 parts of styrene, 1.5 parts of acrylic acid, 1.5 parts of N-butoxymethylacrylamide, 1.5 parts of unsaturated carboxylic acid, 0.5 part of allyl polyalkyl alcohol sulfate ammonium salt, 0.2 part of sodium dodecyl sulfate, 0.8 part of initiator, 8 parts of sodium hydroxide, and 41 parts of deionized water.

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