CN113185917A

CN113185917A - High-light-transmittance anti-cracking water-based paint and preparation method thereof

Info

Publication number: CN113185917A
Application number: CN202110552663.4A
Authority: CN
Inventors: 吴浩; 邱玉恒
Original assignee: Anhui Mingshida New Material Co ltd
Current assignee: Anhui Mingshida New Material Co ltd
Priority date: 2021-05-20
Filing date: 2021-05-20
Publication date: 2021-07-30

Abstract

The invention discloses a high-light-transmission anti-cracking water-based paint, which belongs to the technical field of water-based paint preparation and comprises the following raw materials in parts by weight: 100 parts of main paint, 70-80 parts of curing agent and 5-10 parts of water; the main paint comprises the following components in percentage by weight: 88-90% of methyl methacrylate silicon modified resin, 0.2-0.4% of wetting agent, 0.3-0.5% of flatting agent, 0.1-0.2% of defoaming agent and the balance of food grade ethanol; the curing agent comprises the following components in percentage by weight: 60-70% of food grade ethanol, 0.01-0.02% of dehydrating agent, 10-20% of silane coupling agent, 5-10% of auxiliary agent and the balance of isopropanol; the invention also discloses a preparation method of the water-based paint, wherein the addition of the auxiliary agent can improve the self-repairing performance of the water-based paint and improve the curing speed, and the water-based paint prepared by the invention has excellent high light transmission, cracking resistance and self-repairing performance.

Description

High-light-transmittance anti-cracking water-based paint and preparation method thereof

Technical Field

The invention belongs to the technical field of water-based paint preparation, and particularly relates to high-light-transmittance anti-cracking water-based paint and a preparation method thereof.

Background

The water paint is water paint, including 3 kinds of water soluble, water diluted and water dispersed emulsion paint, and has no benzene, toluene, xylene, formaldehyde and free TDI toxic heavy metal, no toxicity, no irritation, no harm to human body, no environmental pollution, plump paint film, high brightness, high flexibility, water resistance, wear resistance, ageing resistance, yellowing resistance, fast drying, etc. Although the water paint in the prior art is environment-friendly, the water paint has poor film-forming property, hardness and wear resistance, poor gloss, difficult defoaming and no high temperature resistance.

Chinese invention patent CN 107722684A discloses a furniture water paint, which comprises polyurethane water dispersoid, deionized water, a film-forming agent, a defoaming agent, a flatting agent, a wetting agent, a dispersing agent, carbon black, calcium carbonate, nano alumina, a thickening agent, a cross-linking agent, a buffering agent, 2-cerium ethylhexanoate, 2- [1- (ethylsulfonyl) -3 azetidine ] acetonitrile, propylene glycol cetyl polyether-3 acetate, azido diphenyl phosphate and diphenyl carbonate, wherein the hardness and the wear resistance of the invention can reach the normal oily paint, and simultaneously, the invention also has good heat resistance; however, the addition of carbon black, calcium carbonate and nano-alumina reduces the transparency of the water-based paint, and the compatibility of the polymer matrix and the inorganic particle material is low, so that the water-based paint is easy to crack after being cured.

Disclosure of Invention

The invention aims to provide a high-light-transmission anti-cracking water-based paint and a preparation method thereof.

The technical problems to be solved by the invention are as follows:

in the prior art, due to the addition of inorganic particles and pigments, the transmittance of the water-based paint after curing is seriously reduced, the use attractiveness is influenced, and the water-based paint is easy to crack and does not have self-repairing performance.

The purpose of the invention can be realized by the following technical scheme:

the high-light-transmission anti-cracking water-based paint is prepared from the following raw materials in parts by weight: 100 parts of main paint, 70-80 parts of curing agent and 5-10 parts of water;

wherein, the main paint comprises the following components in percentage by weight: 88-90% of methyl methacrylate silicon modified resin, 0.2-0.4% of wetting agent, 0.3-0.5% of flatting agent, 0.1-0.2% of defoaming agent and the balance of food grade ethanol;

the curing agent comprises the following components in percentage by weight: 60-70% of food grade ethanol, 0.01-0.02% of dehydrating agent, 10-20% of silane coupling agent, 5-10% of auxiliary agent and the balance of isopropanol;

the high-light-transmission anti-cracking water-based paint is prepared by the following steps:

adding the main paint, the curing agent and water into a stirring tank, and stirring for 5-20min under the condition of the rotating speed of 100 plus materials and 200rmp to obtain the high-light-transmittance anti-cracking water-based paint.

Further, the auxiliary agent is prepared by the following steps:

step S1, sequentially adding methanol, sodium p-hydroxybenzenesulfonate, ethylenediamine and paraformaldehyde into a three-neck flask, carrying out reflux reaction for 24 hours at the rotating speed of 60-100r/min, filtering after the reaction is finished, washing a filter cake once by using methanol, and drying in an oven at the temperature of 60-65 ℃ to constant weight to obtain an intermediate 1, wherein the dosage ratio of the methanol to the sodium p-hydroxybenzenesulfonate to the ethylenediamine to the paraformaldehyde is 30 mL: 15 mmol: 15 mmol: 1-1.1 g; taking sodium hydroxybenzenesulfonate, ethylenediamine and paraformaldehyde as raw materials, and obtaining an intermediate 1 through Mannich reaction;

the reaction process is as follows:

step S2, adding thioglycolic acid and methanol into a round-bottom flask in a nitrogen atmosphere, then adding dicyclohexylcarbodiimide and N, N-dimethylpyridine, heating to 50-55 ℃, stirring at the rotating speed of 60-100r/min for reaction for 10min, then dropwise adding the methanol solution of the intermediate 1 into the round-bottom flask, ending dropwise adding within 20min, stirring for reaction for 2-4h after finishing dropwise adding, and performing rotary evaporation to obtain a white solid, namely the intermediate 2, wherein the dosage ratio of the thioglycolic acid, the methanol, the dicyclohexylcarbodiimide, the N, N-dimethylpyridine and the methanol solution of the intermediate 1 is 15 mmol: 60mL of: 0.3 g: 0.2-0.5 g: 20 mL; the methanol solution of the intermediate 1 is prepared from the intermediate 1 and methanol according to the dosage ratio of 15 mmol: 20mL of the mixture is mixed; under the action of a condensing agent and a catalyst, the intermediate 1 and thioglycolic acid are subjected to an amide reaction to obtain an intermediate 2;

the reaction process is as follows:

step S3, at room temperature, adding 2-amino-4, 5-dicyanoimidazole into deionized water, then adding hydroxylamine hydrochloride, stirring for 5min, then adding sodium hydroxide, stirring for 10min, then clarifying the reaction solution, then heating to 40 ℃, reacting for 3h, filtering, washing a filter cake for 3-5 times by using deionized water, drying at 50-53 ℃ to constant weight, and obtaining an intermediate 3, wherein the dosage ratio of 2-amino-4, 5-dicyanoimidazole, deionized water, hydroxylamine hydrochloride and sodium hydroxide is 1.33 g: 30-38 mL: 1.8-2.1 g: 1.2 g; oximation is carried out by taking 2-amino-4, 5-dicyanoimidazole as an initiator to obtain an intermediate 3;

the reaction process is as follows:

step S4, adding thioglycolic acid, ethanol and deionized water into a round-bottom flask in a nitrogen atmosphere, then adding dicyclohexylcarbodiimide and N, N-dimethylpyridine, then heating to 60 ℃, stirring for reacting for 10min, then dropwise adding the aqueous solution of the intermediate 3 into the round-bottom flask, stirring for reacting for 2-4h after dropwise adding, and after the reaction is finished, performing rotary evaporation to obtain a solid, namely the intermediate 4, wherein the dosage ratio of the thioglycolic acid, the ethanol, the deionized water, the dicyclohexylcarbodiimide, the N, N-dimethylpyridine to the aqueous solution of the intermediate 3 is 20 mmol: 35-38 mL: 20mL of: 0.3 g: 0.3-0.7 g: 25mL of an aqueous solution of intermediate 3 was prepared from intermediate 3 and deionized water in a 20 mmol: 25mL of the mixture is mixed; under the action of a condensing agent and a catalyst, the intermediate 3 and thioglycolic acid are subjected to an amide reaction to obtain an intermediate 4;

the reaction process is as follows:

step S5, adding the intermediate 2, the intermediate 4 and ethanol into a four-neck flask, stirring and reacting for 5-8min under the protection of nitrogen, dropwise adding a hydrogen peroxide solution with the mass fraction of 30% into the four-neck flask at room temperature, controlling the reaction temperature to be below 50 ℃ by using a water bath during dropwise adding, stirring and reacting for 6h, then adding ethyl acetate, stirring for 1h, transferring the reaction solution into a separating funnel, standing until the reaction solution is layered, then removing a water phase, adding deionized water, shaking and washing, standing and separating liquid, repeating for three times, and finally obtaining an auxiliary agent, wherein the dosage ratio of the intermediate 2, the intermediate 4, the ethanol, the hydrogen peroxide solution and the ethyl acetate is 0.5 mol: 0.5 mol: 40mL of: 35 g: 60mL, and finally carrying out condensation reaction on the intermediate 2 containing the sulfydryl and the intermediate 4 under the action of peroxide in the nitrogen atmosphere to obtain the auxiliary agent.

The reaction process is as follows:

further, the methyl methacrylate modified silicone resin is prepared by the following steps:

step A1, adding trimethoxy silane, toluene and chloroplatinic acid catalyst into a three-neck flask, placing the three-neck flask in an oil bath kettle for magnetic stirring at a constant temperature of 60 ℃, then dropwise adding methyl methacrylate into the three-neck flask, stirring for reaction for 2 hours, heating to 95 ℃, stirring for reaction for 8 hours, cooling to below 40 ℃, heating to 120 ℃ at a heating rate of 2 ℃/min, and carrying out reduced pressure distillation to obtain an intermediate product a; wherein the dosage ratio of the trimethoxy silane, the toluene, the chloroplatinic acid catalyst and the methyl methacrylate is 0.1 mol: 40mL of: 0.3-0.6 g: 0.1 mol;

step A2, adding methyltrimethoxysilane, phenyltrimethoxysilane and an intermediate product a into a three-neck flask, dropwise adding a hydrochloric acid solution with the mass fraction of 17% into the three-neck flask, controlling the dropwise adding speed to be 1 drop/1-2 seconds, hydrolyzing in an oil bath kettle at 30 ℃ for 1 hour after the dropwise adding is finished, heating to 60 ℃, stirring for reacting for 2 hours, and distilling at 85 ℃ for 3 hours to obtain the methyl methacrylate modified silicon resin, wherein the mass ratio of the methyltrimethoxysilane, the phenyltrimethoxysilane, the intermediate product a to the hydrochloric acid solution is 0.5-0.8 g: 1-1.3 g: 1 g: 2.1-2.5 mL.

Further, the wetting agent is a nonionic surfactant having an HLB value of 15 to 17.

Further, the leveling agent is an acrylate copolymer.

Further, the defoaming agent is polyether modified organic silicon.

Further, the dehydrating agent is any one of a molecular sieve and an isocyanate dehydrating agent.

Further, the silane coupling agent is one of KH-55O, KH-560 and KH-570.

Further, the high-light-transmission anti-cracking water-based paint is prepared by the following steps:

The invention has the beneficial effects that:

1. the invention takes main paint, curing agent and water as raw materials to prepare a high-light-transmission anti-cracking water-based paint, and also prepares an auxiliary agent, the addition of the auxiliary agent can improve the self-repairing performance of the water-based paint, improve the curing speed and improve the anti-cracking performance of the water-based paint in many aspects, and the prepared methyl methacrylate modified silicon resin has stable Si-C bonds instead of C-O-Si bonds of the modified silicon resin in the prior art, thereby overcoming the problem that the existing C-O-Si bonds are easy to break under the action of water molecules, keeping the characteristics of organic silicon of the water-based paint, and improving the high-temperature resistance, weather resistance and corrosion resistance of the water-based paint.

2. Taking sodium hydroxybenzenesulfonate, ethylenediamine and paraformaldehyde as raw materials, carrying out Mannich reaction to obtain an intermediate 1, carrying out amide reaction on the intermediate 1 and thioglycolic acid under the action of a condensing agent and a catalyst to obtain an intermediate 2, carrying out oximation on the intermediate 3 by taking 2-amino-4, 5-dicyanoimidazole as an initiator, carrying out amide reaction on the intermediate 3 and the thioglycolic acid under the action of the condensing agent and the catalyst to obtain an intermediate 4, and finally carrying out condensation reaction on the intermediate 2 containing sulfydryl and the intermediate 4 under the action of peroxide under the nitrogen atmosphere to obtain the auxiliary agent, wherein the auxiliary agent contains a sodium sulfonate group, a benzoxazine ring, an imidazole group, a disulfide bond, a primary amine, a secondary amine, a tertiary amine and a hydroxyl group, and the sodium sulfonate group is used as a hydrophilic group to increase the hydrophilic performance of the auxiliary agent and endows the amphiphilic performance to the auxiliary agent, the monomer containing benzoxazine ring can generate ring-opening polymerization reaction at the temperature of 100-120 ℃ under the condition of not adding any catalyst, so as to play a role in crosslinking and polymerization, almost 'zero release' of volatile substances and almost 'zero shrinkage' after curing in the ring-opening polymerization process can generate ring-opening polymerization when the water-based paint is cured and cracked at high temperature, and a self-repairing step is completed, a disulfide bond is introduced into a molecular chain structure, when a material generates cracks, self-repairing is realized through the light exchange or heat exchange reaction of a disulfide bond, imidazole and derivatives thereof not only have a curing effect, but also have special tertiary amine with high catalysis and crosslinking efficiency, so that the addition of an auxiliary agent can improve the curing rate of the water-based paint at room temperature, and hydrogen bonds are formed between N-H and C-O of groups such as primary amine, secondary amine, tertiary amine, hydroxyl group and the like to complete the process, when the coating is damaged, the molecular chains flow to quickly form new hydrogen bonds to realize repair, and repeated repair can be realized for many times, and the repair performance and efficiency are not obviously reduced along with the increase of the repair times, so that the addition of the auxiliary agent can improve the anti-cracking performance of the water-based paint in multiple aspects.

3. According to the invention, hydrosilylation is adopted, trimethoxy silane and methyl methacrylate are subjected to addition reaction under a platinum catalyst to obtain an intermediate product a, the intermediate product a is subjected to hydrolytic condensation with methyltrimethoxy silane and phenyl trimethoxy silane to obtain the methyl methacrylate modified silicon resin, and an organic silicon chain is introduced into acrylic resin, so that a stable Si-C bond is formed between the methacrylic resin and the intermediate product a instead of the C-O-Si bond of the modified silicon resin in the prior art, the problem that the existing C-O-Si bond is easy to break under the action of water molecules is solved, the characteristics of the organic silicon of the water paint are maintained, and the high temperature resistance, weather resistance and corrosion resistance of the water paint are improved.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

The auxiliary agent is prepared by the following steps:

step S1, sequentially adding 30mL of methanol, 15mmol of sodium p-hydroxybenzenesulfonate, 15mmol of ethylenediamine and 1g of paraformaldehyde into a three-neck flask, carrying out reflux reaction for 24 hours at the rotation speed of 60r/min, filtering after the reaction is finished, washing a filter cake once with methanol, and drying in a 60 ℃ oven to constant weight to obtain an intermediate 1;

step S2, adding 15mmol of thioglycolic acid and 60mL of methanol into a round-bottom flask in a nitrogen atmosphere, then adding 0.3g of dicyclohexylcarbodiimide and 0.2g of N, N-dimethylpyridine, subsequently heating to 50 ℃, stirring at a rotating speed of 60r/min for reaction for 10min, dropwise adding 20mL of methanol solution of the intermediate 1 into the round-bottom flask, finishing dropwise adding within 20min, stirring for reaction for 2h after finishing dropwise adding, and performing rotary evaporation to obtain a white solid, namely the intermediate 2 after finishing the reaction;

step S3, adding 1.33g of 2-amino-4, 5-dicyanoimidazole into 30mL of deionized water at room temperature, then adding 1.8g of hydroxylamine hydrochloride, stirring for 5min, then adding 1.2g of sodium hydroxide, stirring for 10min, clarifying the reaction solution, then heating to 40 ℃, reacting for 3h, filtering, washing the filter cake for 3 times by using deionized water, and drying at 50 ℃ to constant weight to obtain an intermediate 3;

step S4, under the nitrogen atmosphere, adding 20mmol of thioglycolic acid, 35mL of ethanol and 20mL of deionized water into a round-bottom flask, then adding 0.3g of dicyclohexylcarbodiimide and 0.3g of N, N-dimethylpyridine, then heating to 60 ℃, stirring for reacting for 10min, dropwise adding 25mL of aqueous solution of the intermediate 3 into the round-bottom flask, after dropwise adding, stirring for reacting for 2h, and after the reaction is finished, performing rotary evaporation to obtain a solid, namely the intermediate 4;

step S5, adding 0.5mol of the intermediate 2, 0.5mol of the intermediate 4 and 40mL of ethanol into a four-neck flask, stirring and reacting for 5min under the protection of nitrogen, dropwise adding 35g of a hydrogen peroxide solution with the mass fraction of 30% into the four-neck flask at room temperature, controlling the reaction temperature to be below 50 ℃ by using a water bath during dropwise adding, stirring and reacting for 6h, adding 60mL of ethyl acetate, stirring for 1h, transferring the reaction solution into a separating funnel, standing until the reaction solution is layered, removing the water phase, adding deionized water, shaking and washing, standing and separating, repeating for three times, and finally obtaining the auxiliary agent.

Example 2

The auxiliary agent is prepared by the following steps:

step S1, sequentially adding 30mL of methanol, 15mmol of sodium p-hydroxybenzenesulfonate, 15mmol of ethylenediamine and 1g of paraformaldehyde into a three-neck flask, carrying out reflux reaction for 24 hours at the rotation speed of 80r/min, filtering after the reaction is finished, washing a filter cake once with methanol, and drying in an oven at the temperature of 62 ℃ to constant weight to obtain an intermediate 1;

step S2, adding 15mmol of thioglycolic acid and 60mL of methanol into a round-bottom flask in a nitrogen atmosphere, then adding 0.3g of dicyclohexylcarbodiimide and 0.4g of N, N-dimethylpyridine, subsequently heating to 52 ℃, stirring at a rotating speed of 80r/min for reaction for 10min, dropwise adding 20mL of methanol solution of the intermediate 1 into the round-bottom flask, finishing dropwise adding within 20min, stirring for reaction for 3h after finishing dropwise adding, and performing rotary evaporation to obtain a white solid, namely the intermediate 2 after finishing the reaction;

step S3, adding 1.33g of 2-amino-4, 5-dicyanoimidazole into 35mL of deionized water at room temperature, then adding 2.0g of hydroxylamine hydrochloride, stirring for 5min, then adding 1.2g of sodium hydroxide, stirring for 10min, clarifying the reaction solution, then heating to 40 ℃, reacting for 3h, filtering, washing the filter cake for 4 times by using deionized water, and drying at 52 ℃ to constant weight to obtain an intermediate 3;

step S4, under the nitrogen atmosphere, adding 20mmol of thioglycolic acid, 37mL of ethanol and 20mL of deionized water into a round-bottom flask, then adding 0.3g of dicyclohexylcarbodiimide and 0.5g of N, N-dimethylpyridine, then heating to 60 ℃, stirring for reacting for 10min, dropwise adding 25mL of aqueous solution of the intermediate 3 into the round-bottom flask, after dropwise adding, stirring for reacting for 3h, and after the reaction is finished, performing rotary evaporation to obtain a solid, namely the intermediate 4;

step S5, adding 0.5mol of the intermediate 2, 0.5mol of the intermediate 4 and 40mL of ethanol into a four-neck flask, stirring and reacting for 7min under the protection of nitrogen, dropwise adding 35g of a hydrogen peroxide solution with the mass fraction of 30% into the four-neck flask at room temperature, controlling the reaction temperature to be below 50 ℃ by using a water bath during dropwise adding, stirring and reacting for 6h, adding 60mL of ethyl acetate, stirring for 1h, transferring the reaction solution into a separating funnel, standing until the reaction solution is layered, removing the water phase, adding deionized water, shaking and washing, standing and separating, repeating for three times, and finally obtaining the auxiliary agent.

Example 3

The auxiliary agent is prepared by the following steps:

step S1, sequentially adding 30mL of methanol, 15mmol of sodium p-hydroxybenzenesulfonate, 15mmol of ethylenediamine and 1.1g of paraformaldehyde into a three-neck flask, carrying out reflux reaction for 24 hours at the rotation speed of 100r/min, filtering after the reaction is finished, washing a filter cake once with methanol, and drying in a 65 ℃ oven to constant weight to obtain an intermediate 1;

step S2, adding 15mmol of thioglycolic acid and 60mL of methanol into a round-bottom flask in a nitrogen atmosphere, then adding 0.3g of dicyclohexylcarbodiimide and 0.5g of N, N-dimethylpyridine, subsequently heating to 55 ℃, stirring at a rotating speed of 100r/min for reaction for 10min, dropwise adding 20mL of methanol solution of the intermediate 1 into the round-bottom flask, finishing dropwise adding within 20min, stirring for reaction for 4h after finishing dropwise adding, and performing rotary evaporation to obtain a white solid, namely the intermediate 2 after finishing the reaction;

step S3, adding 1.33g of 2-amino-4, 5-dicyanoimidazole into 38mL of deionized water at room temperature, then adding 2.1g of hydroxylamine hydrochloride, stirring for 5min, then adding 1.2g of sodium hydroxide, stirring for 10min, clarifying the reaction solution, then heating to 40 ℃, reacting for 3h, filtering, washing the filter cake for 5 times by using deionized water, and drying at 53 ℃ to constant weight to obtain an intermediate 3;

step S4, under the nitrogen atmosphere, adding 20mmol of thioglycolic acid, 38mL of ethanol and 20mL of deionized water into a round-bottom flask, then adding 0.3g of dicyclohexylcarbodiimide and 0.7g of N, N-dimethylpyridine, then heating to 60 ℃, stirring for reacting for 10min, dropwise adding 25mL of aqueous solution of the intermediate 3 into the round-bottom flask, after dropwise adding, stirring for reacting for 4h, and after the reaction is finished, performing rotary evaporation to obtain a solid, namely the intermediate 4;

step S5, adding 0.5mol of the intermediate 2, 0.5mol of the intermediate 4 and 40mL of ethanol into a four-neck flask, stirring and reacting for 8min under the protection of nitrogen, dropwise adding 35g of a hydrogen peroxide solution with the mass fraction of 30% into the four-neck flask at room temperature, controlling the reaction temperature to be below 50 ℃ by using a water bath during dropwise adding, stirring and reacting for 6h, adding 60mL of ethyl acetate, stirring for 1h, transferring the reaction solution into a separating funnel, standing until the reaction solution is layered, removing the water phase, adding deionized water, shaking and washing, standing and separating, repeating for three times, and finally obtaining the auxiliary agent.

Example 4

The methyl methacrylate modified silicone resin is prepared by the following steps:

step A1, adding 0.1mol of trimethoxy silane, 40mL of toluene and 0.3g of chloroplatinic acid catalyst into a three-neck flask, placing the three-neck flask in an oil bath kettle for magnetic stirring at a constant temperature of 60 ℃, then dropwise adding 0.1mol of methyl methacrylate into the three-neck flask, stirring for reaction for 2 hours, heating to 95 ℃, stirring for reaction for 8 hours, cooling to below 40 ℃, heating to 120 ℃ at a heating rate of 2 ℃/min, and carrying out reduced pressure distillation to obtain an intermediate product a;

and A2, adding 0.5g of methyltrimethoxysilane, 1g of phenyltrimethoxysilane and 1g of intermediate product a into a three-neck flask, dropwise adding 1mL of hydrochloric acid solution with the mass fraction of 17% into the three-neck flask, controlling the dropwise adding speed to be 1 drop/1 second, hydrolyzing in an oil bath kettle at 30 ℃ for 1h after the dropwise adding is finished, heating to 60 ℃, stirring for reacting for 2h, and distilling at 85 ℃ for 3h to obtain the methyl methacrylate modified silicon resin.

Example 5

step A1, adding 0.1mol of trimethoxy silane, 40mL of toluene and 0.6g of chloroplatinic acid catalyst into a three-neck flask, placing the three-neck flask in an oil bath kettle for magnetic stirring at a constant temperature of 60 ℃, then dropwise adding 0.1mol of methyl methacrylate into the three-neck flask, stirring for reaction for 2 hours, heating to 95 ℃, stirring for reaction for 8 hours, cooling to below 40 ℃, heating to 120 ℃ at a heating rate of 2 ℃/min, and carrying out reduced pressure distillation to obtain an intermediate product a;

and A2, adding 0.8g of methyltrimethoxysilane, 1.3g of phenyltrimethoxysilane and 1g of intermediate product a into a three-neck flask, dropwise adding 2.5mL of hydrochloric acid solution with the mass fraction of 17% into the three-neck flask, controlling the dropwise adding speed to be 1 drop/2 seconds, hydrolyzing in an oil bath kettle at 30 ℃ for 1h after dropwise adding is finished, heating to 60 ℃, stirring for reacting for 2h, and distilling at 85 ℃ for 3h to obtain the methyl methacrylate modified silicon resin.

Comparative example 1

The comparative example is SH-024 acrylic acid modified organic silicon resin produced by chemical corporation in New four seas of Hubei province.

Example 6

The high-light-transmission anti-cracking water-based paint is prepared from the following raw materials in parts by weight: 100 parts of main paint, 70 parts of curing agent and 5 parts of water;

the main paint comprises the following components in percentage by weight: 88% of methyl methacrylate silicon modified resin, 0.2% of wetting agent, 0.3% of flatting agent, 0.1% of defoaming agent and the balance of food grade ethanol in the embodiment 4;

the curing agent comprises the following components in percentage by weight: 60% of food grade ethanol, 0.01% of dehydrating agent, 10% of silane coupling agent, 5% of auxiliary agent in example 1 and the balance of isopropanol;

adding main paint, curing agent and water into a stirring tank at the rotating speed of 100rm_pStirring for 5min under the condition to obtain the high-light-transmission anti-cracking water-based paint.

Example 7

The high-light-transmission anti-cracking water-based paint is prepared from the following raw materials in parts by weight: 100 parts of main paint, 75 parts of curing agent and 8 parts of water;

the main paint comprises the following components in percentage by weight: 89% of methyl methacrylate silicon modified resin, 0.3% of wetting agent, 0.4% of flatting agent, 0.5% of defoaming agent and the balance of food grade ethanol in the embodiment 5;

the curing agent comprises the following components in percentage by weight: 65% of food grade ethanol, 0.015% of dehydrating agent, 15% of silane coupling agent, 8% of auxiliary agent in example 2 and the balance of isopropanol;

adding main paint, curing agent and water into a stirring tank at a rotating speed of 150rm_pStirring for 10min under the condition to obtain the high-light-transmission anti-cracking water-based paint.

Comparative example 2

the main paint comprises the following components in percentage by weight: 89% of methyl methacrylate silicon modified resin, 0.3% of wetting agent, 0.4% of flatting agent, 0.3% of defoaming agent and the balance of food grade ethanol in the comparative example 1;

the curing agent comprises the following components in percentage by weight: 65% of food grade ethanol, 0.02% of dehydrating agent, 20% of silane coupling agent, 10% of auxiliary agent in example 3 and the balance of isopropanol;

adding main paint, curing agent and water into a stirring tank at the rotating speed of 200rm_pStirring for 20min under the condition to obtain the high-light-transmission anti-cracking water-based paint.

Comparative example 3

The difference between the comparative example and the example 7 is that the auxiliary agent in the curing agent in the example 7 is removed, and the rest raw materials and the preparation process are not changed.

Comparative example 4

The comparative example is L2050 high-quality clear-taste and bright crystal clear finish produced by Guangdong Li magnesium paint Co.

The aqueous paints of examples 6, 7 and comparative examples 2 to 4 were subjected to performance tests according to the following test criteria:

drying time, gloss: testing according to GB/T23999-;

cracking index (mm): coating the groups of water-based paint on a sample plate, wherein the size of the sample plate is 1m multiplied by 1m, the thickness of a coating film is 0.3cm, and after curing at room temperature, carrying out crack resistance measurement according to JC/T951-200 standard;

impact resistance: impact resistance was measured according to the method in GB/T1732;

efficiency of self-healing (%): scratching the coating in the middle of the sample plate along the direction vertical to the stretching axis, slightly applying force on two sides to make the fracture parts tightly contacted, self-healing at room temperature, and calculating self-healing efficiency (self-healing efficiency H is impact resistance before scratching or impact resistance after scratching);

the test results are shown in the following table:

as can be seen from the table above, the performances of examples 6 and 7 in the processes of curing speed, glossiness, cracking resistance and self-repairing performance tests are superior to those of comparative examples 2-4, which shows that the water-based paint prepared by the invention has excellent high light transmittance, cracking resistance and self-repairing performance.

The foregoing is merely exemplary and illustrative of the principles of the present invention and various modifications, additions and substitutions of the specific embodiments described herein may be made by those skilled in the art without departing from the principles of the present invention or exceeding the scope of the claims set forth herein.

Claims

1. The high-light-transmission anti-cracking water-based paint is characterized by comprising the following raw materials in parts by weight: 100 parts of main paint, 70-80 parts of curing agent and 5-10 parts of water;

the auxiliary agent is prepared by the following steps:

step S1, sequentially adding methanol, sodium p-hydroxybenzenesulfonate, ethylenediamine and paraformaldehyde into a three-neck flask, carrying out reflux reaction for 24 hours, and after the reaction is finished, filtering, washing and drying to obtain an intermediate 1;

step S2, adding thioglycollic acid and methanol into a round-bottom flask in a nitrogen atmosphere, then adding dicyclohexylcarbodiimide and N, N-dimethylpyridine, heating to 50-55 ℃, stirring for reacting for 10min, dropwise adding the methanol solution of the intermediate 1, finishing dropwise adding within 20min, stirring for reacting for 2-4h after finishing dropwise adding, and carrying out rotary evaporation to obtain an intermediate 2;

step S3, adding 2-amino-4, 5-dicyanoimidazole into deionized water at room temperature, adding hydroxylamine hydrochloride, stirring for 5min, adding sodium hydroxide, stirring for 10min, heating to 40 ℃, reacting for 3h, filtering, washing and drying a filter cake to obtain an intermediate 3;

step S4, adding thioglycolic acid, ethanol and deionized water into a round-bottom flask in a nitrogen atmosphere, then adding dicyclohexylcarbodiimide and N, N-dimethylpyridine, heating to 60 ℃, stirring for reacting for 10min, dropwise adding the aqueous solution of the intermediate 3 into the round-bottom flask, stirring for reacting for 2-4h after dropwise adding, and performing rotary evaporation to obtain a solid, namely the intermediate 4 after the reaction is finished;

and step S5, adding the intermediate 2, the intermediate 4 and ethanol into a four-neck flask, stirring and reacting for 5-8min under the protection of nitrogen, dropwise adding a hydrogen peroxide solution with the mass fraction of 30% into the four-neck flask at room temperature, controlling the reaction temperature below 50 ℃ in the dropwise adding process, stirring and reacting for 6h, then adding ethyl acetate, stirring for 1h, separating, washing and purifying to obtain the auxiliary agent.

2. The high-transmittance crack-resistant water-based paint according to claim 1, wherein the methyl methacrylate modified silicone resin is prepared by the following steps:

step A1, adding trimethoxy silane, toluene and chloroplatinic acid catalyst into a three-neck flask, placing the three-neck flask in an oil bath kettle for magnetic stirring at a constant temperature of 60 ℃, then dropwise adding methyl methacrylate into the three-neck flask, stirring for reaction for 2 hours, heating to 95 ℃, stirring for reaction for 8 hours, cooling to below 40 ℃, heating to 120 ℃ at a heating rate of 2 ℃/min, and carrying out reduced pressure distillation to obtain an intermediate product a;

and A2, adding methyltrimethoxysilane, phenyltrimethoxysilane and an intermediate product a into a three-neck flask, dropwise adding a hydrochloric acid solution with the mass fraction of 17% into the three-neck flask, controlling the dropwise adding speed to be 1 drop/1-2 seconds, hydrolyzing in an oil bath kettle at 30 ℃ for 1h after the dropwise adding is finished, heating to 60 ℃, stirring for reacting for 2h, and distilling at 85 ℃ for 3h to obtain the methyl methacrylate modified silicon resin.

3. The high-transmittance anti-cracking water-based paint according to claim 1, wherein the wetting agent is a nonionic surfactant with HLB value of 15-17, the leveling agent is an acrylate copolymer, the defoaming agent is polyether modified organosilicon, the dehydrating agent is any one of a molecular sieve and an isocyanate dehydrating agent, and the silane coupling agent is one of KH-55O, KH-560 and KH-570.

4. The preparation method of the high-light-transmission anti-cracking water-based paint as claimed in claim 1, characterized by comprising the following steps:

and adding the main paint, the curing agent and water into a stirring tank, and stirring for 5-20min to obtain the high-light-transmittance anti-cracking water-based paint.