Low-temperature construction latex paint and preparation method thereof

Abstract

The present invention relates to a low-temperature construction latex paint and a preparation method thereof. The low-temperature construction latex paint is mainly prepared from the following components according to the following mass ratio: #imgabs0# This invention overcomes the shortcomings of existing ordinary latex paints that require the addition of a large amount of antifreeze under low-temperature conditions, which easily leads to excessively high VOC content and also causes the workability and coating performance of the latex paint to decline. Through the coordinated coordination of low-temperature film-forming emulsion, neutral silica sol, silane coupling agent and other preferred components in the system and their usage ratios, the invention has the advantages of excellent comprehensive performance such as low-temperature film-forming property, low-temperature storage stability, freeze-thaw resistance, scrub resistance and resistance to artificial weathering aging.

Description

Technical Field

[0001] The invention relates to a low-temperature construction latex paint and a preparation method thereof, and is applied in the field of latex paint production. Background Art

[0002] The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

[0003] Winter construction (low-temperature construction) refers to workers continuing to work on-site even when the outdoor temperature drops below 5°C. When temperatures drop to 0°C in many northern regions, raw materials on the construction site become hard and brittle, and water-containing materials such as concrete and mortar gradually freeze. Without remedial measures through technical means, construction will be difficult to continue. Latex paint is a type of water-based coating made from a synthetic resin emulsion, supplemented with pigments, fillers, and other additives. Latex paint uses water as a dispersion medium and contains only small amounts of organic solvents. As environmental awareness grows and environmental regulations tighten the limits on volatile organic compounds in coatings, it is gaining popularity among consumers.

[0004] During the film-forming process, latex paint requires the dispersion medium to evaporate, allowing the long polymer chains in the paint to fully unfold and entangle. Therefore, latex paints have certain requirements for water evaporation time and application temperature. Furthermore, the polymer compounds in latex paint are dispersed in water as latex particles. During storage, if the ambient temperature is below the freezing point of water, the latex paint will freeze, disrupting the latex particle structure and causing demulsification. Most common latex paints currently on the market require application at temperatures above 5°C. Below 5°C, these paints experience decreased film-forming and ductility, prone to cracking; poor adhesion, bulging, and flaking; and reduced weatherability, water resistance, stain resistance, and alkali resistance, resulting in fading and chalking. To address these issues, large amounts of antifreeze agents (such as ethylene glycol and propylene glycol) are often added to common latex paints. However, excessive use of antifreeze agents can lead to excessively high VOC levels in the paint, impairing the paint's workability and film properties.

[0005] Therefore, it is urgent to provide a low-temperature construction latex paint with excellent comprehensive performance such as low-temperature film forming property, low-temperature storage stability, freeze-thaw resistance, scrub resistance and resistance to artificial weathering and the like, and a preparation method thereof. Summary of the Invention

[0006] In order to overcome the shortcomings of existing ordinary latex paints that require the addition of a large amount of antifreeze under low temperature conditions below 5°C, which easily leads to an excessively high VOC content in the paint and also causes the workability and coating performance of the latex paint to decline, the present invention provides a low-temperature construction latex paint and a preparation method thereof. Through the synergistic combination of a preferred low-temperature film-forming emulsion, a neutral silica sol, a silane coupling agent and other preferred components in the system and their usage ratios, the latex paint has the advantages of excellent comprehensive performance such as low-temperature film-forming property, low-temperature storage stability, freeze-thaw resistance, scrub resistance and resistance to artificial weathering aging.

[0007] The technical solutions of the present invention are as follows:

[0008] A low-temperature application latex paint is mainly prepared from the following components in the following mass ratios:

[0009]

[0010]

[0011] The low-temperature film-forming emulsion is one of styrene-acrylate polymer emulsion, anionic acrylic copolymer emulsion or vinyl acetate-butyl acrylate polymer emulsion, or any combination of any two or more thereof, wherein the glass transition temperature of the styrene-acrylate polymer emulsion, the anionic acrylic copolymer emulsion and the vinyl acetate-butyl acrylate polymer emulsion are all ≤-20°C, and internal plasticizing monomers and self-crosslinking monomers are introduced during the emulsion polymerization process;

[0012] The silane coupling agent is prepared by mixing 3-glycidyloxypropyltrimethoxysilane, ethyl orthosilicate and 3-methacryloxypropyltrimethoxysilane in a mass ratio of 1:2-3:8-12;

[0013] The pH value of the neutral silica sol is 7-8.

[0014] The low-temperature construction latex paint of the present application has the advantages of excellent comprehensive performance such as low-temperature film-forming property, low-temperature storage stability, freeze-thaw resistance, scrub resistance and resistance to artificial weathering aging through the synergistic combination of preferred low-temperature film-forming emulsion, neutral silica sol, silane coupling agent and other preferred components in the system and their usage ratio. It can form a film smoothly at low temperatures of 0 to -20°C and has excellent paint film performance; it can be stored and used for a long time at 0 to -20°C; and there is no ice crystal problem during low-temperature construction.

[0015] The assisting effects of silane coupling agent, low-temperature film-forming emulsion and neutral silica sol are as follows: (1) Low-temperature film-forming emulsion is the main film-forming material, and its glass transition temperature is ≤-20℃. In addition, internal plasticizing monomers and self-crosslinking monomers are introduced into the system during the emulsion polymerization process, which ensures that the emulsion can form a film smoothly at 0~-20℃; (2) Neutral silica sol is the secondary film-forming material, and its neutral pH value can prevent the low-temperature film-forming emulsion from decomposing. In addition, the unmodified highly active surface hydroxyl groups give it the ability to form a film at 0~-20℃. (3) The reaction of silane coupling agent with neutral silica sol further improves the compatibility of neutral silica sol with low-temperature film-forming emulsion, and improves the scrubbing resistance and film strength of the paint film; (4) The combined action of silane coupling agent, low-temperature film-forming emulsion and neutral silica sol, as well as the coordinated coordination with other preferred components in the system and their dosage ratios, solves the problem of ice crystals in existing ordinary latex paints during low-temperature construction. Among them, the functions of silane coupling agents are as follows: (1) Silane coupling agents can react with neutral silica sol, and then the silane coupling agents are grafted onto silica, which changes the surface properties of silica. The organic long chains and the polymer chains in the emulsion are entangled with each other, which improves the compatibility with the emulsion. While ensuring the low-temperature film-forming performance of the latex paint, it also improves the scrubbing resistance and coating strength of the paint film; (2) After hydrolysis, the silane coupling agent can react with kaolin, talc and other powders containing silanol groups on the surface. The silane coupling agent reacts with kaolin, talc, etc., and then the silane coupling agent is grafted onto the silanol groups on the surface of the powder, which greatly improves the dispersibility of the powder and improves the color development and water permeability of the latex paint film without destroying the low-temperature performance of the latex paint; (3) The silane coupling agent increases the viscosity of the slurry after reacting with kaolin, talc, etc., providing high shear force for powder grinding, so that the grinding stage of the preparation process can still ensure that the slurry fineness is ≤60μm without adding any thickeners such as cellulose ether.

[0016] The dispersant is one of polyacrylate sodium salt, polyacrylate ammonium salt, hydrophobically modified polyacrylate sodium salt or hydrophobically modified polyacrylate ammonium salt, or any combination of any two or more thereof.

[0017] The preferred dispersant has a better dispersing effect.

[0018] The defoaming agent is a mineral oil defoaming agent.

[0019] The preferred defoaming agent has low cost and good defoaming effect.

[0020] The film-forming aid is an alcohol ester film-forming aid or a dibutyl carboxylate film-forming aid.

[0021] The preferred film-forming aid has good film-forming effect.

[0022] The antifreeze agent is one of ethylene glycol, 1,2-propylene glycol or polyethylene glycol, or any combination of any two or more thereof.

[0023] The preferred antifreeze agent has good antifreeze effect.

[0024] The thickener is one of an alkali-swellable emulsion thickener, a hydrophobically modified alkali-swellable emulsion thickener, or a polyurethane associative thickener, or any combination of any two or more thereof.

[0025] The preferred thickener has high thickening efficiency and good viscosity stability.

[0026] The method for preparing the low-temperature application latex paint comprises the following steps performed in sequence:

[0027] (1) Preparation of silane coupling agent

[0028] 3-glycidyloxypropyltrimethoxysilane, ethyl orthosilicate and 3-methacryloxypropyltrimethoxysilane are uniformly mixed in a mass ratio of 1:2-3:8-12 to obtain the silane coupling agent;

[0029] (2) Grinding steps

[0030] (1) Add 50-62.5% of water by weight to the reactor, start the stirrer and adjust the stirrer speed to 300-500 r / min, add a dispersant, a pH adjuster and a defoamer accounting for 25-75% of the water by weight to the water, and disperse for 3-5 minutes;

[0031] (2) adding titanium dioxide, kaolin and talc to the mixture obtained in step (1), then increasing the stirrer speed to 800-1200 r / min and dispersing for 3-5 minutes;

[0032] (3) adding a silane coupling agent and 25-37% water by weight to the mixture obtained in step (2), then increasing the stirrer speed to 1400-1600 r / min, and dispersing the mixture until the slurry fineness is ≤60 μm to obtain a grinding raw material;

[0033] (3) Paint mixing steps

[0034] (1) Adjust the stirrer speed to 800-1200 r / min, add neutral silica sol to the ground material, and disperse for 3-5 minutes;

[0035] (2) adding the low-temperature film-forming emulsion, antifreeze agent, film-forming aid, remaining defoamer, thickener and remaining water to the mixture obtained in step (1) and dispersing for 3 to 5 minutes to obtain the low-temperature application latex paint.

[0036] The preparation method of the low-temperature construction latex paint of the present application has simple steps and is easy to operate.

[0037] Compared with the prior art, the present invention has the following advantages:

[0038] 1) The low-temperature application latex paint of the present application has the advantages of excellent comprehensive performance such as low-temperature film-forming property, low-temperature storage stability, freeze-thaw resistance, scrub resistance and artificial weathering resistance through the synergistic combination of the preferred low-temperature film-forming emulsion, neutral silica sol, silane coupling agent and other preferred components in the system and their usage ratios. It can smoothly form a film at low temperatures of 0 to -20°C and has excellent paint film properties; it can be stored and used for a long time at 0 to -20°C; and there is no ice crystal problem during low-temperature application;

[0039] 2) The preparation method of the low-temperature construction latex paint has simple steps and is easy to operate. DETAILED DESCRIPTION

[0040] The following will clearly and completely describe the technical solutions of the present invention in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0041] Table 1 Components and dosage ratios of each embodiment and comparative example

[0042]

[0043] Example 1

[0044] The components and usage ratios of the low-temperature application latex paint described in the present invention are detailed in Table 1.

[0045] The method for preparing the low-temperature application latex paint comprises the following steps performed in sequence:

[0046] (1) Preparation of silane coupling agent

[0047] 3-glycidyloxypropyltrimethoxysilane, ethyl orthosilicate and 3-methacryloxypropyltrimethoxysilane are uniformly mixed in a mass ratio of 1:2.5:10 to obtain the silane coupling agent;

[0048] (2) Grinding steps

[0049] (1) 132.5 parts by mass of water was added to the reactor, the stirrer was started and the stirrer speed was adjusted to 400 r / min, 1.5 parts by mass of polyacrylic acid sodium salt dispersant, 3 parts by mass of pH regulator and 1 part by mass of mineral oil defoamer were added to the water in sequence, and the mixture was dispersed for 4 minutes;

[0050] (2) 173 parts by mass of titanium dioxide, 100 parts by mass of kaolin, and 60 parts by mass of talc were added to the mixture obtained in step (1), and then the stirrer speed was increased to 1000 r / min and dispersed for 4 minutes;

[0051] (3) adding 4 parts by mass of a silane coupling agent and 74 parts by mass of water to the mixture obtained in step (2), then increasing the stirrer speed to 1500 r / min, and dispersing until the slurry fineness is ≤60 μm to obtain a ground material;

[0052] (3) Paint mixing steps

[0053] (1) Adjust the stirrer speed to 1000 r / min, add 79 parts by mass of neutral silica sol to the ground material, and disperse for 4 minutes;

[0054] (2) To the mixture obtained in step (1), 316 parts by mass of styrene-acrylate polymer emulsion, 21 parts by mass of ethylene glycol, 2 parts by mass of alcohol ester film-forming aid, 1 part by mass of mineral oil defoamer, 6 parts by mass of alkali swellable emulsion thickener and 27 parts by mass of water were added in sequence, and dispersed for 4 minutes to obtain the low-temperature application latex paint.

[0055] The glass transition temperature of the styrene-acrylate polymer emulsion is ≤-20°C, and an internal plasticizing monomer and a self-crosslinking monomer are introduced during the emulsion polymerization process;

[0056] The pH value of the neutral silica sol is 7.5.

[0057] Example 2

[0058] The components and usage ratios of the low-temperature application latex paint described in the present invention are detailed in Table 1.

[0059] The method for preparing the low-temperature application latex paint comprises the following steps performed in sequence:

[0060] (1) Preparation of silane coupling agent

[0061] 3-glycidyloxypropyltrimethoxysilane, ethyl orthosilicate and 3-methacryloxypropyltrimethoxysilane are uniformly mixed in a mass ratio of 1:2:12 to obtain the silane coupling agent;

[0062] (2) Grinding steps

[0063] (1) 132.5 parts by mass of water was added to the reactor, the stirrer was started and the stirrer speed was adjusted to 300 r / min, 1.5 parts by mass of polyacrylate ammonium salt dispersant, 3 parts by mass of pH regulator and 1 part by mass of mineral oil defoamer were added to the water in sequence, and the mixture was dispersed for 5 minutes;

[0064] (2) 173 parts by mass of titanium dioxide, 100 parts by mass of kaolin, and 60 parts by mass of talc were added to the mixture obtained in step (1), and then the stirrer speed was increased to 800 r / min and dispersed for 5 minutes;

[0065] (3) adding 8 parts by mass of a silane coupling agent and 70 parts by mass of water to the mixture obtained in step (2), then increasing the stirrer speed to 1400 r / min, and dispersing the mixture until the slurry fineness is ≤60 μm to obtain a ground material;

[0066] (3) Paint mixing steps

[0067] (1) Adjust the stirrer speed to 800 r / min, add 79 parts by mass of neutral silica sol to the ground material, and disperse for 5 minutes;

[0068] (2) To the mixture obtained in step (1), 316 parts by mass of anionic acrylic copolymer emulsion, 21 parts by mass of ethylene glycol, 2 parts by mass of alcohol ester film-forming aid, 1 part by mass of mineral oil defoamer, 6 parts by mass of alkali swellable emulsion thickener and 27 parts by mass of water were added in sequence, and dispersed for 3 minutes to obtain the low-temperature application latex paint.

[0069] The glass transition temperature of the anionic acrylic copolymer emulsion is ≤-20°C, and an internal plasticizing monomer and a self-crosslinking monomer are introduced during the emulsion polymerization process;

[0070] The pH value of the neutral silica sol is 7.

[0071] Example 3

[0072] The components and usage ratios of the low-temperature application latex paint described in the present invention are detailed in Table 1.

[0073] The method for preparing the low-temperature application latex paint comprises the following steps performed in sequence:

[0074] (1) Preparation of silane coupling agent

[0075] 3-glycidyloxypropyltrimethoxysilane, ethyl orthosilicate and 3-methacryloxypropyltrimethoxysilane are uniformly mixed in a mass ratio of 1:3:8 to obtain the silane coupling agent;

[0076] (2) Grinding steps

[0077] (1) 132.5 parts by mass of water were added to the reactor, the stirrer was started and the stirrer speed was adjusted to 500 r / min, 1.5 parts by mass of hydrophobically modified polyacrylic acid sodium salt dispersant, 3 parts by mass of pH regulator and 1 part by mass of mineral oil defoamer were added to the water in sequence, and the mixture was dispersed for 3 minutes;

[0078] (2) 173 parts by mass of titanium dioxide, 100 parts by mass of kaolin, and 60 parts by mass of talc were added to the mixture obtained in step (1), and then the stirrer speed was increased to 1200 r / min and dispersed for 3 minutes;

[0079] (3) adding 8 parts by mass of a silane coupling agent and 66 parts by mass of water to the mixture obtained in step (2), then increasing the stirrer speed to 1600 r / min, and dispersing the mixture until the slurry fineness is ≤60 μm to obtain a ground material;

[0080] (3) Paint mixing steps

[0081] (1) Adjust the stirrer speed to 1200 r / min, add 72 parts by mass of neutral silica sol to the ground material, and disperse for 3 minutes;

[0082] (2) To the mixture obtained in step (1), 288 parts by mass of a low-temperature film-forming emulsion, 21 parts by mass of 1,2-propylene glycol, 2 parts by mass of an alcohol ester film-forming aid, 1 part by mass of a mineral oil defoamer, 6 parts by mass of a hydrophobically modified alkali-swellable emulsion thickener, and 66 parts by mass of water were successively added, and the mixture was dispersed for 5 minutes to obtain the low-temperature application latex paint.

[0083] The glass transition temperature of the vinyl acetate-butyl acrylate polymer emulsion is ≤-20°C, and an internal plasticizing monomer and a self-crosslinking monomer are introduced during the emulsion polymerization process;

[0084] The pH value of the neutral silica sol is 8.

[0085] Example 4

[0086] The components and usage ratios of the low-temperature application latex paint described in the present invention are detailed in Table 1.

[0087] The method for preparing the low-temperature application latex paint comprises the following steps performed in sequence:

[0088] (1) Preparation of silane coupling agent

[0089] 3-glycidyloxypropyltrimethoxysilane, ethyl orthosilicate and 3-methacryloxypropyltrimethoxysilane are uniformly mixed in a mass ratio of 1:2.5:10 to obtain the silane coupling agent;

[0090] (2) Grinding steps

[0091] (1) 107 parts by mass of water was added to the reactor, the stirrer was started and the stirrer speed was adjusted to 400 r / min, and 2 parts by mass of hydrophobically modified polyacrylate ammonium salt dispersant, 4 parts by mass of pH regulator and 0.5 parts by mass of mineral oil defoamer were added to the water in sequence, and dispersed for 4 minutes;

[0092] (2) 200 parts by mass of titanium dioxide, 100 parts by mass of kaolin, and 100 parts by mass of talc were added to the mixture obtained in step (1), and then the stirrer speed was increased to 1000 r / min and dispersed for 4 minutes;

[0093] (3) adding 6 parts by mass of silane coupling agent and 63 parts by mass of water to the mixture obtained in step (2), then increasing the stirrer speed to 1500 r / min, and dispersing until the slurry fineness is ≤60 μm to obtain a grinding raw material;

[0094] (3) Paint mixing steps

[0095] (1) Adjust the stirrer speed to 1000 r / min, add 80 parts by mass of neutral silica sol to the ground material, and disperse for 4 minutes;

[0096] (2) 150 parts by mass of styrene-acrylate polymer emulsion, 150 parts by mass of anionic acrylic copolymer emulsion, 25 parts by mass of 1,2-propylene glycol, 2 parts by mass of dibutyl carboxylate film-forming aid, 1.5 parts by mass of mineral oil defoamer, 6 parts by mass of hydrophobically modified alkali swellable emulsion thickener and 3 parts by mass of water are added to the mixture obtained in step (1) in sequence, and dispersed for 4 minutes to obtain the low-temperature application latex paint.

[0097] The glass transition temperature of the styrene-acrylate polymer emulsion and the anionic acrylic copolymer emulsion is ≤-20°C, and an internal plasticizing monomer and a self-crosslinking monomer are introduced during the emulsion polymerization process;

[0098] The pH value of the neutral silica sol is 7.

[0099] Example 5

[0100] The components and usage ratios of the low-temperature application latex paint described in the present invention are detailed in Table 1.

[0101] The method for preparing the low-temperature application latex paint comprises the following steps performed in sequence:

[0102] (1) Preparation of silane coupling agent

[0103] 3-glycidyloxypropyltrimethoxysilane, ethyl orthosilicate and 3-methacryloxypropyltrimethoxysilane are uniformly mixed in a mass ratio of 1:2:8 to obtain the silane coupling agent;

[0104] (2) Grinding steps

[0105] (1) 100 parts by mass of water was added to the reactor, the stirrer was started and the stirrer speed was adjusted to 300 r / min, 3 parts by mass of dispersant, 5 parts by mass of pH regulator and 2 parts by mass of mineral oil defoamer were added to the water in sequence, and the mixture was dispersed for 3 minutes;

[0106] (2) adding 150 parts by mass of titanium dioxide, 78 parts by mass of kaolin, and 50 parts by mass of talc to the mixture obtained in step (1), then increasing the stirrer speed to 1200 r / min and dispersing for 5 minutes;

[0107] (3) adding 8 parts by mass of a silane coupling agent and 50 parts by mass of water to the mixture obtained in step (2), then increasing the stirrer speed to 1400 r / min, and dispersing the mixture until the slurry fineness is ≤60 μm to obtain a ground material;

[0108] (3) Paint mixing steps

[0109] (1) Adjust the stirrer speed to 800 r / min, add 100 parts by mass of neutral silica sol to the ground material, and disperse for 3 minutes;

[0110] (2) 100 parts by mass of styrene-acrylate polymer emulsion, 200 parts by mass of anionic acrylic copolymer emulsion, 100 parts by mass of vinyl acetate-butyl acrylate polymer emulsion, 30 parts by mass of polyethylene glycol, 3 parts by mass of dibutyl carboxylate film-forming aid, 4 parts by mass of mineral oil defoamer, 10 parts by mass of polyurethane associative thickener and 10 parts by mass of water are added to the mixture obtained in step (1) in sequence, and the mixture is dispersed for 5 minutes to obtain the low-temperature application latex paint.

[0111] The glass transition temperatures of the styrene-acrylate polymer emulsion, the anionic acrylic copolymer emulsion, and the vinyl acetate-butyl acrylate polymer emulsion are all ≤-20°C, and internal plasticizing monomers and self-crosslinking monomers are introduced during the emulsion polymerization process;

[0112] The pH value of the neutral silica sol is 8.

[0113] Example 6

[0114] The components and usage ratios of the low-temperature application latex paint described in the present invention are detailed in Table 1.

[0115] The method for preparing the low-temperature application latex paint comprises the following steps performed in sequence:

[0116] (1) Preparation of silane coupling agent

[0117] 3-glycidyloxypropyltrimethoxysilane, ethyl orthosilicate and 3-methacryloxypropyltrimethoxysilane are uniformly mixed in a mass ratio of 1:3:12 to obtain the silane coupling agent;

[0118] (2) Grinding steps

[0119] (1) 140 parts by mass of water was added to the reactor, the stirrer was started and the stirrer speed was adjusted to 500 r / min, 1 part by mass of dispersant, 3 parts by mass of pH regulator and 1.5 parts by mass of mineral oil defoamer were added to the water in sequence, and the mixture was dispersed for 5 minutes;

[0120] (2) adding 250 parts by mass of titanium dioxide, 125 parts by mass of kaolin, and 72 parts by mass of talc to the mixture obtained in step (1), then increasing the stirrer speed to 1200 r / min and dispersing for 5 minutes;

[0121] (3) adding 3 parts by mass of a silane coupling agent and 100 parts by mass of water to the mixture obtained in step (2), then increasing the stirrer speed to 1600 r / min, and dispersing the mixture until the slurry fineness is ≤60 μm to obtain a ground material;

[0122] (3) Paint mixing steps

[0123] (1) Adjust the stirrer speed to 1200 r / min, add 50 parts by mass of neutral silica sol to the ground material, and disperse for 5 minutes;

[0124] (2) 100 parts by mass of anionic acrylic copolymer emulsion, 100 parts by mass of vinyl acetate-butyl acrylate polymer emulsion, 20 parts by mass of polyethylene glycol, 1 part by mass of dibutyl carboxylate film-forming aid, 0.5 parts by mass of mineral oil defoamer, 3 parts by mass of polyurethane associative thickener and 30 parts by mass of water are added to the mixture obtained in step (1) in sequence, and the mixture is dispersed for 3 minutes to obtain the low-temperature application latex paint.

[0125] The glass transition temperatures of the anionic acrylic copolymer emulsion and the vinyl acetate-butyl acrylate polymer emulsion are both ≤-20°C, and internal plasticizing monomers and self-crosslinking monomers are introduced during the emulsion polymerization process;

[0126] The pH value of the neutral silica sol is 7.5.

[0127] Experimental data:

[0128] Comparative Example 1

[0129] The difference between this comparative example and Example 1 is that equal parts by mass of 3-glycidyloxypropyltrimethoxysilane (manufacturer: Nengde New Materials, model: SCA-E87M) are used instead of the silane coupling agent in Example 1 (see Table 1 for the components and usage ratios).

[0130] Comparative Example 2

[0131] The difference between this comparative example and Example 1 is that equal parts by mass of 3-methacryloxypropyltrimethoxysilane (manufacturer: Nengde New Materials, model: SCA-R74M) are used instead of the silane coupling agent in Example 1 (see Table 1 for the components and usage ratios).

[0132] Comparative Example 3

[0133] The difference between this comparative example and Example 1 is that an equal amount of pure acrylic elastic emulsion (manufacturer: Wanhua Chemical Group Co., Ltd., model: Archsol TT114) is used to replace the low-temperature film-forming emulsion in Example 1 (see Table 1 for the components and usage ratios).

[0134] Comparative Example 4

[0135] The difference between this comparative example and Example 1 is that an equal amount of alkaline silica sol (manufacturer: Xiamen Peiteng Material Technology Co., Ltd., model S100, pH = 9.5-10.5) is used instead of the neutral silica sol in Example 1 (the components and usage ratios are shown in Table 1).

[0136] Detection method:

[0137] 1. Low-temperature film-forming property: The latex paint of each embodiment and comparative example was applied to an asbestos-free fiber cement board of 50 mm × 200 mm × (3-6) mm in size using a wet film preparation apparatus. The paint film thickness was 100 μm (the cement board and the wet film preparation apparatus were both frozen at -20±2°C for 2 hours). The cement board was then placed at -20±2°C for 24 hours. After being taken out, the coating surface was abraded with the fingertips. If the surface was not broken by abrasion, it was recorded as film-forming.

[0138] 2. Low temperature storage stability: According to GB / T 6753.3-86 "Test method for storage stability of coatings", in addition to changing the storage temperature to 0 to -20°C, the temperature for measuring the coating viscosity before and after storage is uniformly adjusted to 25°C.

[0139] 3. Freeze-thaw resistance: According to GB / T 9268-2008 "Determination of freeze-thaw resistance of latex paints", except that the freezer temperature is changed to -20℃.

[0140] 4. Scrub resistance: According to GB / T 9266-2009 "Determination of Scrub Resistance of Architectural Paint Coatings".

[0141] 5. Resistance to artificial weathering: in accordance with the requirements of Cycle A in GB 1865-2009 "Paints and varnishes - Artificial weathering and artificial radiation exposure - filtered xenon arc radiation".

[0142] The test results are shown in Table 2:

[0143] Table 2 Performance test data of latex paint in each embodiment and comparative example

[0144]

[0145] As can be seen from Table 2, the low-temperature application latex paints in Examples 1 to 6 all have good low-temperature film-forming properties, freeze-thaw resistance, low-temperature storage stability, paint film appearance, scrub resistance, and artificial weathering resistance, and their overall performance is better than that of the comparative examples. Comparative Examples 1 and 2 replace the silane coupling agent in the low-temperature application latex paint with 3-glycidyloxypropyltrimethoxysilane or 3-methacryloxypropyltrimethoxysilane. Although they still have low-temperature film-forming properties, ice crystals appear on the surface of the paint film, and the low-temperature storage stability, scrub resistance, and artificial weathering resistance all fail to pass the tests. Comparative Example 3 replaces the low-temperature film-forming emulsion in the low-temperature application latex paint with a pure acrylic elastic emulsion, which loses the low-temperature film-forming properties. Comparative Example 4 replaces the neutral silica sol in the low-temperature application latex paint with an alkaline silica sol, which also loses the low-temperature film-forming properties.

Claims

1. A low-temperature application latex paint, characterized by: It is mainly prepared from the following components in the following mass ratios: 200-400 parts of low-temperature film-forming emulsion 50-100 parts of neutral silica sol 3-8 parts of silane coupling agent 150-250 parts of titanium dioxide 75-125 parts of kaolin 50-100 parts of talcum powder 20-30 parts antifreeze 3-10 parts thickener 3-5 parts pH adjuster 2 to 6 parts of defoaming agent 1 to 3 parts dispersant 1 to 3 parts of film-forming aid 160-270 parts water; The low-temperature film-forming emulsion is one of styrene-acrylate polymer emulsion, anionic acrylic copolymer emulsion or vinyl acetate-butyl acrylate polymer emulsion, or any combination of any two or more thereof, wherein the glass transition temperature of the styrene-acrylate polymer emulsion, the anionic acrylic copolymer emulsion and the vinyl acetate-butyl acrylate polymer emulsion are all ≤-20°C, and internal plasticizing monomers and self-crosslinking monomers are introduced during the emulsion polymerization process; The silane coupling agent is prepared by mixing 3-glycidyloxypropyltrimethoxysilane, ethyl orthosilicate and 3-methacryloxypropyltrimethoxysilane in a mass ratio of 1:2-3:8-12; The pH value of the neutral silica sol is 7 to 8; The preparation method of the low-temperature application latex paint comprises the following steps performed in sequence: (1) Preparation of silane coupling agent 3-glycidyloxypropyltrimethoxysilane, ethyl orthosilicate and 3-methacryloxypropyltrimethoxysilane are uniformly mixed in a mass ratio of 1:2-3:8-12 to obtain the silane coupling agent; (2) Grinding steps (1) Add 50-62.5% of water by weight into the reactor, start the stirrer and adjust the stirrer speed to 300-500 r / min, add dispersant, pH regulator and 25-75% of defoamer by weight into the water, and disperse for 3-5 minutes; (2) titanium dioxide, kaolin and talc are added to the mixture obtained in step (1), and then the stirrer speed is increased to 800-1200 r / min and dispersed for 3-5 minutes; (3) adding a silane coupling agent and 25-37% water by weight to the mixture obtained in step (2), then increasing the stirrer speed to 1400-1600 r / min, and dispersing the mixture until the slurry fineness is ≤60 μm to obtain a grinding raw material; (3) Paint mixing steps (1) Adjust the mixer speed to 800-1200 r / min, add neutral silica sol to the ground material, and disperse for 3-5 minutes; (2) Adding the low-temperature film-forming emulsion, antifreeze agent, film-forming aid, remaining defoamer, thickener and remaining water to the mixture obtained in step (1) and dispersing for 3 to 5 minutes to obtain the low-temperature application latex paint.

2. The low-temperature application latex paint according to claim 1, characterized in that: The dispersant is one of polyacrylate sodium salt, polyacrylate ammonium salt, hydrophobically modified polyacrylate sodium salt or hydrophobically modified polyacrylate ammonium salt, or any combination of any two or more thereof.

3. The low-temperature application latex paint according to claim 1, characterized in that: The defoaming agent is a mineral oil defoaming agent.

4. The low-temperature application latex paint according to claim 1, characterized in that: The film-forming aid is an alcohol ester film-forming aid or a dibutyl carboxylate film-forming aid.

5. The low-temperature application latex paint according to claim 1, characterized in that: The antifreeze agent is one of ethylene glycol, 1,2-propylene glycol or polyethylene glycol, or any combination of any two or more thereof.

6. The method for preparing a low-temperature application latex paint according to any one of claims 1 to 5, characterized in that: It includes the following steps in order: (1) Preparation of silane coupling agent 3-glycidyloxypropyltrimethoxysilane, ethyl orthosilicate and 3-methacryloxypropyltrimethoxysilane are uniformly mixed in a mass ratio of 1:2-3:8-12 to obtain the silane coupling agent; (2) Grinding steps (1) Add 50-62.5% of water by weight into the reactor, start the stirrer and adjust the stirrer speed to 300-500 r / min, add dispersant, pH regulator and 25-75% of defoamer by weight into the water, and disperse for 3-5 minutes; (2) titanium dioxide, kaolin and talc are added to the mixture obtained in step (1), and then the stirrer speed is increased to 800-1200 r / min and dispersed for 3-5 minutes; (3) adding a silane coupling agent and 25-37% water by weight to the mixture obtained in step (2), then increasing the stirrer speed to 1400-1600 r / min, and dispersing the mixture until the slurry fineness is ≤60 μm to obtain a grinding raw material; (3) Paint mixing steps (1) Adjust the mixer speed to 800-1200 r / min, add neutral silica sol to the ground material, and disperse for 3-5 minutes; (2) Adding the low-temperature film-forming emulsion, antifreeze agent, film-forming aid, remaining defoamer, thickener and remaining water to the mixture obtained in step (1) and dispersing for 3 to 5 minutes to obtain the low-temperature application latex paint.

Images