A styrene-acrylic emulsion, a preparation method and application thereof

Abstract

The application belongs to the technical field of building coatings and relates to a styrene-acrylic emulsion, which comprises the following components in parts by mass: styrene 1-40 parts, butyl acrylate 1-30 parts, acid monomer 0.1-1 part, acrylamide 0.01-1 part, film-forming solvent 0.01-1 part, crosslinking agent 0.01-1 part, anionic emulsifier 0.1-2 parts, non-ionic emulsifier 0.1-2 parts, oxidizing agent 0.01-0.5 part, reducing agent 0.01-0.5 part, initiator 0.01-1 part, pH buffer 0.01-0.5 part, neutralizing agent 0.1-1 part, defoaming agent 0.02-1 part, preservative 0.02-1 part and water 44-56 parts. The application further provides a preparation method of the styrene-acrylic emulsion and application of the styrene-acrylic emulsion in interior wall coating. The interior wall coating prepared by using the styrene-acrylic emulsion does not need solvent, and the coating has excellent washability, low-temperature stability and wash resistance.

Description

Technical Field

[0001] This invention belongs to the field of architectural coatings technology, and relates to a styrene-acrylic emulsion, its preparation method, and its application. Background Technology

[0002] Interior wall emulsions can be made into interior wall coatings and applied to the interior walls of buildings in various scenarios to achieve both protective and decorative effects. Currently, products on the market do not add hydrophilic solvents and film-forming solvents when making interior wall coatings. Simply lowering the glass transition temperature of the emulsion cannot meet the requirements for solvent-free coatings. Chinese patent number ZL108285505A uses high-EO anions as the main emulsifier, which has high water absorption and low scrub resistance. Therefore, it is necessary to use more expensive functional monomers to balance the scrub resistance. Styrene is added in two stages. First, it is easy to reverse and become a hard core. Second, even if polystyrene becomes a hard shell or hard segment, its strong hydrophobicity improves the scrub resistance. At the same time, it requires high hydrophilicity of the system, which means that a high amount of high-EO emulsifier is needed. In addition, its residual monomers are easy to treat and have a high content of volatile substances. Summary of the Invention

[0003] In order to solve the problems existing in the prior art, the present invention provides a styrene-acrylic emulsion. The interior wall coating made using the styrene-acrylic emulsion does not require solvents, and the coating has excellent washability, low temperature stability and brush retention.

[0004] The specific technical solution adopted in this invention is as follows:

[0005] A styrene-acrylic emulsion, comprising, by mass parts: 1-40 parts styrene, 1-30 parts butyl acrylate, 0.1-1 parts acidic monomers, 0.01-1 parts acrylamide, 0.01-1 parts film-forming solvent, 0.01-1 parts crosslinking agent, 0.1-2 parts anionic emulsifier, 0.1-2 parts nonionic emulsifier, 0.01-0.5 parts oxidant, 0.01-0.5 parts reducing agent, 0.01-1 parts initiator, 0.01-0.5 parts pH buffer, 0.1-1 parts neutralizer, 0.02-1 parts defoamer, 0.02-1 parts preservative, and 44-56 parts water.

[0006] Furthermore, the acid monomer is at least one of acrylic acid, itaconic acid, fumaric acid, maleic acid, and 2-acrylamido-2-methylpropanesulfonic acid;

[0007] Furthermore, the crosslinking agent is at least one of vinyltrimethoxysilane, vinyltriethoxysilane, and γ-methacryloyloxypropyltrimethoxysilane.

[0008] Furthermore, the anionic emulsifier is at least one of the following: sodium salt of fatty alcohol polyoxyethylene ether (3-6 EO), disodium alkyl alcohol ether (2-6 EO) succinate monoester, and sodium salt of fatty alcohol polyoxyethylene ether (4-8 EO).

[0009] Furthermore, the nonionic emulsifier is at least one of isomeric undecyl alcohol polyoxyethylene ether (40 EOs) and isomeric tridecyl alcohol polyoxyethylene ether (40 EOs).

[0010] Furthermore, the initiator is one of ammonium persulfate, potassium persulfate, or sodium persulfate.

[0011] The preparation method of the above-mentioned styrene-acrylic emulsion includes the following steps:

[0012] A. Preparation of the base solution: Weigh 15-20 parts of water, 0.02-0.5 parts of anionic emulsifier, and 0.01-0.5 parts of pH buffer, add them to container a, and heat to 65-80 degrees to obtain the base solution;

[0013] B. Preparation of the pre-emulsion: Weigh 12-16 parts of water, 0.06-1 parts of anionic emulsifier, and 0.05-1 parts of nonionic emulsifier, add them to container a and stir evenly. Then add 0.25-10 parts of styrene, 0.8-24 parts of butyl acrylate, and 0.05-0.5 parts of acid monomers, and stir evenly to obtain the pre-emulsion.

[0014] C. Preparation of initiator solution: Weigh 0.01-1 part of initiator, add it to 4-6 parts of water, stir well to obtain initiator solution;

[0015] D. Preparation of the downstream pre-emulsion: Weigh 13-14 parts water, 0.02-0.5 parts anionic emulsifier, and 0.05-1 parts nonionic emulsifier, add them to container b and stir evenly. Then add 0.75-30 parts styrene, 0.2-6 parts butyl acrylate, 0.01-1 parts film-forming solvent, 0.05-0.5 parts acid monomer, 0.01-1 parts acrylamide, and 0.01-1 parts crosslinking agent, stir evenly to obtain the downstream pre-emulsion.

[0016] E. Preparation of seed emulsion: Weigh 5-10% of the pre-emulsion and add it to the base liquid in step A. When the temperature reaches 65-82℃, add 25-35% of the initiator solution and react for 15-20 minutes.

[0017] F. Preparation of styrene-acrylic emulsion: After the seed emulsion reacts for 15-20 minutes, add the remaining pre-emulsion dropwise over 2-3 hours at a temperature of 66-84℃. Simultaneously, the initiating solution is added dropwise over 3.5-4.5 hours without interruption. After the pre-emulsion is completely added, maintain the temperature for 30-45 minutes. Then, add the post-emulsion dropwise over 30-40 minutes at a temperature of 80-84℃. After the dropwise addition is complete, maintain the temperature for 1.5-2.0 hours. Then, simultaneously add 0.01-0.5 parts of oxidant and 0.01-0.5 parts of reducing agent over 20-35 minutes. After the dropwise addition is complete, maintain the temperature for 25-35 minutes. Finally, add 0.1-1 parts of neutralizing agent, 0.02-1 parts of defoamer, and 0.02-1 parts of preservative. Stir until homogeneous to obtain the styrene-acrylic emulsion.

[0018] As described above, the styrene-acrylic emulsion is used as a component of an interior wall coating. The interior wall coating, by weight, comprises the following components: 16-22 parts water, 0.4-1 part hydroxyethyl cellulose, 0.05-0.2 parts 2-amino-2-methyl-1-propanol, 3 parts titanium dioxide, 32-56 parts filler, 5-24 parts film-forming solvent, 8-12 parts styrene-acrylic emulsion, 0.1-1 part defoamer, 0.1-1 part dispersant, 0.1-0.5 part wetting agent, 0.01-0.5 parts thickener, 0.1-1 part preservative, and 0.2-1 part mildew inhibitor.

[0019] Furthermore, the filler comprises 25-40 parts of heavy calcium carbonate with a mesh size of 600-800, 5-10 parts of calcined kaolin with a mesh size of 3750-4250, and 2-6 parts of washed kaolin with a mesh size of 3750-4250.

[0020] The beneficial effects of this invention are:

[0021] 1. This invention uses simple, high-charge raw materials, including pH buffers and neutralizers, which are all high-charge phosphate-based inorganic substances. This provides excellent stability in emulsion polymerization, excellent dispersion stability of pigments and fillers in interior wall coatings, a reduction in the freezing point of water due to water ionization, and excellent adhesion to the substrate.

[0022] 2. This invention uses an internal film-forming agent to aid film formation, giving the system excellent film-forming properties without the need for an external film-forming solvent. In addition, the amount of hard monomer is relatively high, resulting in low cost and excellent scrub resistance.

[0023] 3. This invention uses hydrophilic monomers that form hydrogen bonds with water to lower the freezing point of water, while also having excellent water retention properties, enabling interior wall coatings to have excellent open time without hydrophilic solvents, thus resulting in excellent workability.

[0024] 4. This invention employs two-stage polymerization, combined with an internal film-forming agent, to enable the system to exhibit excellent film-forming properties under solvent-free conditions, resulting in solvent-free interior wall coatings with superior performance.

[0025] 5. The interior wall coating of the present invention uses cellulose thickener, which has excellent water retention. In addition, the long-chain EO of polyurethane leveling agent can also provide a certain water retention. Combined with styrene-acrylic emulsion, high-performance solvent-free interior wall coatings can be prepared. Detailed Implementation

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention.

[0027] The oxidant in this invention is at least one of tert-butyl hydrogen peroxide and hydrogen peroxide; the reducing agent is at least one of sodium hypophosphite, sodium bisulfite, vitamin C, and sodium formaldehyde sulfoxylate; the initiator is one of ammonium persulfate, potassium persulfate, or sodium persulfate; the defoamer is a mineral oil defoamer; and the water is deionized water. Unless otherwise specified, all other raw materials used can be purchased commercially. I. Specific Implementation Methods

[0029] Example 1

[0030] The acid monomers in this embodiment are a mixture of itaconic acid and acrylic acid in a 1:1 ratio.

[0031] Film-forming solvent; dioctyl maleate;

[0032] The crosslinking agent is: vinyltrimethoxysilane.

[0033] Anionic emulsifier: Disodium alkyl alcohol ether succinate monoester;

[0034] Nonionic emulsifier: Iso-undecyl alcohol polyoxyethylene ether;

[0035] Oxidizing agent: tert-butyl hydrogen peroxide;

[0036] Reducing agent: Sodium hypophosphite;

[0037] Initiator: Ammonium persulfate;

[0038] pH buffer: disodium hydrogen phosphate;

[0039] Neutralizing agent: Sodium pyrophosphate;

[0040] A. Preparation of the base solution: Weigh 20 parts water, 0.2 parts anionic emulsifier, and 0.1 parts disodium hydrogen phosphate, add them to reaction vessel a, and heat to 80 degrees to obtain the base solution.

[0041] B. Preparation of the pre-emulsion: Weigh 15 parts water, 0.6 parts anionic emulsifier, and 0.1 parts nonionic emulsifier, add them to emulsification tank a and stir evenly. Then add 5 parts styrene, 20 parts butyl acrylate, and 0.2 parts acid monomers, and stir evenly to obtain the pre-emulsion.

[0042] C. Preparation of initiator solution: Weigh 0.25 parts of initiator, add to 6 parts of water, stir evenly to obtain initiator solution;

[0043] D. Preparation of the downstream pre-emulsion: Weigh 13 parts water, 0.2 parts anionic emulsifier, and 0.1 parts nonionic emulsifier, add them to emulsification tank b and stir evenly. Then add 15 parts styrene, 5 parts butyl acrylate, 0.5 parts reactive film-forming solvent, 0.085 parts acid monomer, 0.05 parts acrylamide, and 0.02 parts crosslinking agent, stir evenly to obtain the downstream pre-emulsion.

[0044] E. Preparation of seed emulsion: Weigh 8% of the pre-emulsion and add it to the base liquid obtained in step A. When the temperature reaches 78°C, add 30% of the initiator solution and react for 18 minutes.

[0045] F. Preparation of styrene-acrylic emulsion: After the seed emulsion reacts for 18 minutes, the remaining pre-emulsion is added dropwise over 2 hours at a temperature of 80°C. The initiating solution is added simultaneously over 3.5 hours without interruption. After the pre-emulsion is completely added, the mixture is kept warm for 40 minutes. Then, the post-emulsion is added dropwise over 40 minutes at a temperature of 82°C. After the addition is complete, the mixture is kept warm for 1.8 hours. Then, 0.2 parts of oxidant and 0.2 parts of reducing agent are added simultaneously over 30 minutes. After the addition is complete, the mixture is kept warm for 30 minutes. Finally, 0.5 parts of neutralizing agent, 0.5 parts of defoamer, and 0.5 parts of preservative are added. After stirring evenly, the styrene-acrylic emulsion is obtained.

[0046] Example 2

[0047] The acid monomers in this embodiment are a mixture of itaconic acid and acrylic acid in a mass ratio of 1:1.

[0048] Film-forming solvent; dioctyl maleate;

[0049] The crosslinking agent is: vinyltrimethoxysilane.

[0050] Anionic emulsifier: Disodium alkyl alcohol ether succinate monoester;

[0051] Nonionic emulsifier: Iso-undecyl alcohol polyoxyethylene ether;

[0052] Oxidizing agent: tert-butyl hydrogen peroxide;

[0053] Reducing agent: Sodium hypophosphite;

[0054] Initiator: Ammonium persulfate;

[0055] pH buffer: disodium hydrogen phosphate;

[0056] Neutralizing agent: Sodium pyrophosphate;

[0057] A. Preparation of the base solution: Weigh 20 parts water, 0.2 parts anionic emulsifier, and 0.1 parts pH buffer, add them to reaction vessel a, and heat to 65 degrees to obtain the base solution.

[0058] B. Preparation of the pre-emulsion: Weigh 15 parts water, 0.6 parts anionic emulsifier, and 0.1 parts nonionic emulsifier, add them to emulsification tank a and stir evenly. Then add 5 parts styrene, 20 parts butyl acrylate, and 0.2 parts acid monomers, and stir evenly to obtain the pre-emulsion.

[0059] C. Preparation of initiator solution: Weigh 0.25 parts of initiator, add to 6 parts of water, stir evenly to obtain initiator solution;

[0060] D. Preparation of the downstream pre-emulsion: Weigh 13 parts water, 0.2 parts anionic emulsifier, and 0.1 parts nonionic emulsifier, add them to emulsification tank b and stir evenly. Then add 15 parts styrene, 5 parts butyl acrylate, 0.5 parts reactive film-forming solvent, 0.085 parts acid monomer, 0.05 parts acrylamide, and 0.02 parts crosslinking agent, stir evenly to obtain the downstream pre-emulsion.

[0061] E. Preparation of seed emulsion: Weigh 8% of the pre-emulsion and add it to the base liquid obtained in step A. When the temperature reaches 66℃, add 30% of the initiator solution and react for 18 minutes.

[0062] F. Preparation of styrene-acrylic emulsion: After the seed emulsion reacts for 18 minutes, the remaining pre-emulsion is added dropwise over 2 hours at a temperature of 68°C. The initiating solution is added simultaneously over 3.5 hours without interruption. After the pre-emulsion is completely added, the mixture is kept warm for 40 minutes. Then, the post-emulsion is added dropwise over 40 minutes at a temperature of 70°C. After the addition is complete, the mixture is kept warm for 1.8 hours. Then, 0.2 parts of oxidant and 0.2 parts of reducing agent are added simultaneously over 30 minutes. After the addition is complete, the mixture is kept warm for 30 minutes. Finally, 0.5 parts of neutralizing agent, 0.5 parts of defoamer, and 0.5 parts of preservative are added. After stirring evenly, the styrene-acrylic emulsion is obtained.

[0063] Example 3

[0064] The acidic monomers in this embodiment are a mixture of fumaric acid, 2-acrylamido-2-methylpropanesulfonic acid, and maleic acid in a ratio of 1:2:2.

[0065] Film-forming solvent; dibutyl maleate;

[0066] The crosslinking agent is: γ-methacryloyloxypropyltrimethoxysilane.

[0067] Anionic emulsifier: Sodium salt of fatty alcohol polyoxyethylene ether sulfate;

[0068] Nonionic emulsifier: Isotridecyl alcohol polyoxyethylene ether;

[0069] Oxidizing agent: hydrogen peroxide;

[0070] Reducing agent: a mixture of sodium bisulfite and vitamin C in a 1:1 mass ratio;

[0071] Initiator: Potassium persulfate;

[0072] pH buffer: Sodium bicarbonate;

[0073] Neutralizing agent: Sodium carbonate;

[0074] A. Preparation of the base solution: Weigh 15 parts water, 0.5 parts anionic emulsifier, and 0.5 parts pH buffer, add them to reaction vessel a, and heat to 68 degrees to obtain the base solution;

[0075] B. Preparation of the pre-emulsion: Weigh 16 parts water, 0.06 parts anionic emulsifier, and 0.05 parts nonionic emulsifier, add them to emulsification kettle a and stir evenly. Then add 0.25 parts styrene, 0.8 parts butyl acrylate, and 0.05 parts acid monomers, and stir evenly to obtain the pre-emulsion.

[0076] C. Preparation of initiator solution: Weigh 0.01 parts of initiator, add to 4 parts of water, stir evenly to obtain initiator solution;

[0077] D. Preparation of the downstream pre-emulsion: Weigh 13 parts water, 0.02 parts anionic emulsifier, and 0.05 parts nonionic emulsifier, add them to emulsification tank b and stir evenly. Then add 0.75 parts styrene, 0.2 parts butyl acrylate, 0.01 parts film-forming solvent, 0.05 parts acid monomer, 0.01 parts acrylamide, and 0.01 parts crosslinking agent and stir evenly to obtain the downstream pre-emulsion.

[0078] E. Preparation of seed emulsion: Weigh 5% of the pre-emulsion and add it to the base liquid obtained in step A. When the temperature reaches 65℃, add 25% of the initiator solution and react for 15 minutes.

[0079] F. Preparation of styrene-acrylic emulsion: After the seed emulsion reacts for 15 minutes, the remaining pre-emulsion is added dropwise over 2 hours at a temperature of 66°C. The initiating solution is added simultaneously over 3.5 hours without interruption. After the pre-emulsion is completely added, the mixture is kept warm for 30 minutes. Then, the post-emulsion is added dropwise over 30 minutes at a temperature of 80°C. After the addition is complete, the mixture is kept warm for 1.5 hours. Then, 0.01 parts of oxidant and 0.01 parts of reducing agent are added simultaneously over 20 minutes. After the addition is complete, the mixture is kept warm for 25 minutes. Finally, 0.1 parts of neutralizing agent, 0.02 parts of defoamer, and 0.02 parts of preservative are added. After stirring evenly, the styrene-acrylic emulsion is obtained.

[0080] Example 4

[0081] The acid monomer in this embodiment is maleic acid.

[0082] Film-forming solvent; diisooctyl maleate;

[0083] The crosslinking agent is: vinyltriethoxysilane.

[0084] Anionic emulsifier: fatty alcohol polyoxyethylene ether;

[0085] Nonionic emulsifier: Isotridecyl alcohol polyoxyethylene ether;

[0086] Oxidizing agent: hydrogen peroxide;

[0087] Reducing agent: Sodium formaldehyde sulfoxylate;

[0088] Initiator: Ammonium persulfate;

[0089] pH buffer: Sodium dihydrogen phosphate;

[0090] Neutralizing agent: Sodium carbonate;

[0091] A. Preparation of the base solution: Weigh 20 parts water, 0.5 parts anionic emulsifier, and 0.5 parts pH buffer, add them to container a, and heat to 80 degrees to obtain the base solution.

[0092] B. Preparation of the pre-emulsion: Weigh 16 parts water, 1 part anionic emulsifier, and 1 part nonionic emulsifier, add them to container a and stir evenly. Then add 10 parts styrene, 24 parts butyl acrylate, and 0.5 parts acid monomers, and stir evenly to obtain the pre-emulsion.

[0093] C. Preparation of initiator solution: Weigh 1 part of initiator, add it to 6 parts of water, stir well to obtain initiator solution;

[0094] D. Preparation of the downstream pre-emulsion: Weigh 14 parts water, 0.5 parts anionic emulsifier, and 1 part nonionic emulsifier, add them to container b and stir evenly. Then add 30 parts styrene, 6 parts butyl acrylate, 1 part film-forming solvent, 0.5 parts acid monomer, 1 part acrylamide, and 1 part crosslinking agent and stir evenly to obtain the downstream pre-emulsion.

[0095] E. Preparation of seed emulsion: Weigh 10% of the pre-emulsion and add it to the base liquid obtained in step A. When the temperature reaches 82℃, add 35% of the initiator solution and react for 20 minutes.

[0096] F. Preparation of styrene-acrylic emulsion: After the seed emulsion reacts for 20 minutes, the remaining pre-emulsion is added dropwise over 3 hours at a temperature of 84°C. The initiating solution is added simultaneously over 4.5 hours without interruption. After the pre-emulsion is completely added, the mixture is kept warm for 45 minutes. Then, the post-emulsion is added dropwise over 40 minutes at a temperature of 84°C. After the addition is complete, the mixture is kept warm for 2 hours. Then, 0.5 parts of oxidant and 0.5 parts of reducing agent are added simultaneously over 35 minutes. After the addition is complete, the mixture is kept warm for 35 minutes. Finally, 1 part of neutralizing agent, 1 part of defoamer, and 1 part of preservative are added. After stirring evenly, the styrene-acrylic emulsion is obtained.

[0097] Comparative Example 1

[0098] The only difference between Comparative Example 1 and Example 1 is the preparation process; Comparative Example 1 does not use segmented polymerization.

[0099] The acid monomers in this embodiment are a mixture of itaconic acid and acrylic acid in a 1:1 ratio.

[0100] Film-forming solvent; dioctyl maleate;

[0101] The crosslinking agent is: vinyltrimethoxysilane.

[0102] Anionic emulsifier: Disodium alkyl alcohol ether succinate monoester;

[0103] Nonionic emulsifier: Iso-undecyl alcohol polyoxyethylene ether;

[0104] Oxidizing agent: tert-butyl hydrogen peroxide;

[0105] Reducing agent: Sodium hypophosphite;

[0106] Initiator: Ammonium persulfate;

[0107] pH buffer: disodium hydrogen phosphate;

[0108] Neutralizing agent: Sodium pyrophosphate;

[0109] A. Preparation of the base solution: Weigh 20 parts water, 0.2 parts anionic emulsifier, and 0.1 parts disodium hydrogen phosphate, add them to reaction vessel a, and heat to 80 degrees to obtain the base solution.

[0110] B. Preparation of pre-emulsion: Weigh 18 parts water, 0.8 parts anionic emulsifier, and 0.2 parts nonionic emulsifier, add them to the emulsification tank and stir evenly. Then add 20 parts styrene, 25 parts butyl acrylate, 0.285 parts acid monomer, 0.05 parts acrylamide, and 0.02 parts crosslinking agent, and stir evenly to obtain the pre-emulsion.

[0111] C. Preparation of initiator solution: Weigh 0.25 parts of initiator, add to 6 parts of water, stir evenly to obtain initiator solution;

[0112] D. Preparation of seed emulsion: Weigh 8% of the pre-emulsion and add it to the base liquid obtained in step A. When the temperature reaches 78℃, add 30% of the initiator solution and react for 18 minutes.

[0113] F. Preparation of styrene-acrylic emulsion: After the seed emulsion reacts for 18 minutes, the remaining pre-emulsion is added dropwise over 2 hours at a temperature of 80°C. The initiating solution is added simultaneously over 3.5 hours without interruption. After the emulsion is completely added, the mixture is kept at this temperature for 40 minutes. Then, 0.2 parts of oxidant and 0.2 parts of reducing agent are added dropwise over 30 minutes. After the addition is complete, the mixture is kept at this temperature for 30 minutes. Finally, 0.5 parts of neutralizing agent, 0.5 parts of defoamer, and 0.5 parts of preservative are added and stirred until homogeneous to obtain the styrene-acrylic emulsion.

[0114] II. Performance Testing

[0115] The styrene-acrylic emulsions prepared in the above examples and comparative examples were used to make interior wall coatings. Performance tests were conducted according to GB / T9756-2018, including the brush resistance test method: the test sample was diluted with water (50% water content), stored in a 250ml container, and the lid was closed. The temperature and humidity chamber was adjusted to 40℃, and the diluted sample and a plastered asbestos-free cement board were placed in the chamber and left to stand for at least 2 hours. The wool brush did not need to be heated but required ion removal treatment by soaking in pure water. Once the sample and board were at a constant temperature, the experiment could begin. A suitable amount of coating was applied evenly to the board surface using a wool brush. After completion, the sample and board were returned to a 40℃ oven for constant temperature. After 10 minutes, a second coat was applied, repeating this process for a total of 5 coats. The condition of the board surface and the brush were then scored, with a maximum score of 5 points and a minimum score of 0 points.

[0116] Table 1

[0117]

[0118]

[0119] As shown in Table 1, the interior wall coating prepared using the styrene-acrylic emulsion of the embodiments of the present invention has no lumps, is uniform in state, has good workability, normal coating appearance, brushing resistance ≥4, good alkali resistance, scrub resistance ≥1820, and good low temperature stability.

[0120] As can be seen from Examples 1-4, the present invention found in the experiment that the interior wall coating prepared by using styrene-acrylic emulsion obtained by low-temperature polymerization has better washability and can also reduce energy consumption in the preparation process.

Claims

1. A method for preparing a styrene-acrylic emulsion, characterized in that, The styrene-acrylic emulsion, by mass parts, comprises the following components: 1-40 parts styrene, 1-30 parts butyl acrylate, 0.1-1 parts acidic monomers, 0.01-1 parts acrylamide, 0.01-1 parts film-forming solvent, 0.01-1 parts crosslinking agent, 0.1-2 parts anionic emulsifier, 0.1-2 parts nonionic emulsifier, 0.01-0.5 parts oxidant, 0.01-0.5 parts reducing agent, 0.01-1 parts initiator, 0.01-0.5 parts pH buffer, 0.1-1 parts neutralizer, 0.02-1 parts defoamer, 0.02-1 parts preservative, and 44-56 parts water; wherein the film-forming solvent is at least one selected from dibutyl maleate, dioctyl maleate, and diisooctyl maleate. The preparation method includes the following steps: A. Preparation of the base solution: Weigh 15-20 parts of water, 0.02-0.5 parts of anionic emulsifier, and 0.01-0.5 parts of pH buffer, add them to reaction vessel a, and heat to 65-80 degrees to obtain the base solution; B. Preparation of the pre-emulsion: Weigh 12-16 parts of water, 0.06-1 parts of anionic emulsifier, and 0.05-1 parts of nonionic emulsifier, add them to emulsification tank a and stir evenly. Then add 0.25-10 parts of styrene, 0.8-24 parts of butyl acrylate, and 0.05-0.5 parts of acid monomers, and stir evenly to obtain the pre-emulsion. C. Preparation of initiator solution: Weigh 0.01-1 part of initiator, add it to 4-6 parts of water, stir well to obtain initiator solution; D. Preparation of the downstream pre-emulsion: Weigh 13-14 parts water, 0.02-0.5 parts anionic emulsifier, and 0.05-1 parts nonionic emulsifier, add them to emulsification tank b and stir evenly. Then add 0.75-30 parts styrene, 0.2-6 parts butyl acrylate, 0.01-1 parts film-forming solvent, 0.05-0.5 parts acid monomer, 0.01-1 parts acrylamide, and 0.01-1 parts crosslinking agent, stir evenly to obtain the downstream pre-emulsion. E. Preparation of seed emulsion: Weigh 5-10% of the pre-emulsion and add it to the base liquid in step A. When the temperature reaches 65-82℃, add 25-35% of the initiator solution and react for 15-20 minutes. F. Preparation of styrene-acrylic emulsion: After the seed emulsion reacts for 15-20 minutes, add the remaining pre-emulsion dropwise over 2-3 hours at a temperature of 66-84℃. Simultaneously, the initiating solution is added dropwise over 3.5-4.5 hours without interruption. After the pre-emulsion is completely added, maintain the temperature for 30-45 minutes. Then, add the post-emulsion dropwise over 30-40 minutes at a temperature of 80-84℃. After the dropwise addition is complete, maintain the temperature for 1.5-2.0 hours. Then, simultaneously add 0.01-0.5 parts of oxidant and 0.01-0.5 parts of reducing agent over 20-35 minutes. After the dropwise addition is complete, maintain the temperature for 25-35 minutes. Finally, add 0.1-1 parts of neutralizing agent, 0.02-1 parts of defoamer, and 0.02-1 parts of preservative. Stir until homogeneous to obtain the styrene-acrylic emulsion.

2. The method for preparing styrene-acrylic emulsion according to claim 1, characterized in that: The acid monomers are at least one of acrylic acid, itaconic acid, fumaric acid, maleic acid, and 2-acrylamido-2-methylpropanesulfonic acid.

3. The method for preparing styrene-acrylic emulsion according to claim 1, characterized in that: The crosslinking agent is at least one of vinyltrimethoxysilane, vinyltriethoxysilane, and γ-methacryloyloxypropyltrimethoxysilane.

4. The method for preparing styrene-acrylic emulsion according to claim 1, characterized in that: The anionic emulsifier is at least one of the following: sodium sulfate of fatty alcohol polyoxyethylene ether (3-6 EOs), disodium alkyl alcohol ether (2-6 EOs) succinate monoester, and sodium sulfate of fatty alcohol polyoxyethylene ether (4-8 EOs).

5. The method for preparing styrene-acrylic emulsion according to claim 1, characterized in that: The nonionic emulsifier is at least one of isomeric undecyl alcohol polyoxyethylene ether (40 EOs) and isomeric tridecyl alcohol polyoxyethylene ether (40 EOs).

6. The method for preparing styrene-acrylic emulsion according to claim 1, characterized in that: The pH buffer is at least one of disodium hydrogen phosphate, sodium dihydrogen phosphate, and sodium bicarbonate. The neutralizing agent is at least one of sodium pyrophosphate and sodium carbonate.

7. The application of the styrene-acrylic emulsion according to claim 1, characterized in that: The styrene-acrylic emulsion is used as a component of the interior wall coating. The interior wall coating, by weight, comprises the following components: 16-22 parts water, 0.4-1 parts hydroxyethyl cellulose, 0.05-0.2 parts 2-amino-2-methyl-1-propanol, 3 parts titanium dioxide, 32-56 parts filler, 5-24 parts film-forming solvent, 8-12 parts styrene-acrylic emulsion, 0.1-1 part defoamer, 0.1-1 part dispersant, 0.1-0.5 parts wetting agent, 0.01-0.5 parts thickener, 0.1-1 part preservative, and 0.2-1 part mildew inhibitor.

8. The application of the styrene-acrylic emulsion according to claim 7, characterized in that: The filler comprises 25-40 parts of heavy calcium carbonate with a mesh size of 600-800, 5-10 parts of calcined kaolin with a mesh size of 3750-4250, and 2-6 parts of washed kaolin with a mesh size of 3750-4250.

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