阅读说明：本技术 防混凝土粘附的建筑铝合金模板用表面涂料及其制备方法 (Surface coating for building aluminum alloy template for preventing concrete adhesion and preparation method thereof ) 是由 费邦忠 周正华 查全达 费安道 于 2020-03-10 设计创作，主要内容包括：本发明公开了一种防混凝土粘附的建筑铝合金模板用表面涂料及其制备方法,该防混凝土粘附的建筑铝合金模板用表面涂料由如下质量份的原料组成：改性环氧树脂15-30份、改性二氧化钛5-15份、聚四氟乙烯粉末15-25份、乙酸乙酯30-50份、N-甲基-2-吡咯烷酮5-10份、固化剂0.5-3份、消泡剂0.5-3份；本发明通过使用改性环氧树脂、改性二氧化钛和聚四氟乙烯粉末共混,提高涂料的防粘性能和化学稳定性、耐热性、机械性能等其它性能；通过对环氧树脂进行改性,使环氧树脂不仅对金属具有优异的粘附力,同时成膜后具有较低的表面能,有利于涂料的防粘性能。(The invention discloses a surface coating for a building aluminum alloy template for preventing concrete adhesion and a preparation method thereof, wherein the surface coating for the building aluminum alloy template for preventing concrete adhesion is composed of the following raw materials in parts by mass: 15-30 parts of modified epoxy resin, 5-15 parts of modified titanium dioxide, 15-25 parts of polytetrafluoroethylene powder, 30-50 parts of ethyl acetate, 5-10 parts of N-methyl-2-pyrrolidone, 0.5-3 parts of curing agent and 0.5-3 parts of defoaming agent; according to the invention, the modified epoxy resin, the modified titanium dioxide and the polytetrafluoroethylene powder are blended, so that the anti-sticking performance, the chemical stability, the heat resistance, the mechanical property and other properties of the coating are improved; by modifying the epoxy resin, the epoxy resin not only has excellent adhesion to metal, but also has lower surface energy after film forming, thereby being beneficial to the anti-sticking performance of the coating.)

1. The surface coating for the building aluminum alloy template for preventing concrete adhesion is characterized by comprising the following raw materials in parts by mass: 15-30 parts of modified epoxy resin, 5-15 parts of modified titanium dioxide, 15-25 parts of polytetrafluoroethylene powder, 30-50 parts of ethyl acetate, 5-10 parts of N-methyl-2-pyrrolidone, 0.5-3 parts of curing agent and 0.5-3 parts of defoaming agent;

the preparation method of the modified epoxy resin comprises the following steps:

s1, under the protection of nitrogen, adding bisphenol A and epichlorohydrin into a reaction bottle, heating to 70-80 ℃ under stirring, adding tetrabutylammonium bromide, reacting for 4-8h, and distilling the reaction liquid under reduced pressure to obtain an intermediate I;

s2, under the protection of nitrogen, adding the intermediate I and toluene into a reaction bottle, heating to 70-80 ℃ under stirring, adding sodium hydroxide, and reacting for 2-5h to obtain a solution I;

s3, adding bisphenol A into the solution I, heating to 75-80 ℃, reacting for 2-5h, cooling the reaction liquid to room temperature, adding disodium hydrogen phosphate to adjust the pH value to 6-7, filtering, washing the filtrate with deionized water for 3 times, and then carrying out reduced pressure distillation to obtain bisphenol A epoxy resin;

s4, under the protection of nitrogen, dissolving hexafluorobutyl acrylate and vinyl ethoxy dimethyl silane in toluene, adding potassium persulfate, heating to 60-70 ℃ for reaction for 10-20h, carrying out reduced pressure distillation, adding water and an emulsifier into the reaction solution, and continuously stirring for 2-3h to obtain a fluorine-silicon polymerization emulsion;

and S5, adding the bisphenol A epoxy resin into a reaction bottle under the protection of nitrogen, heating to 70-90 ℃, adding dibutyltin dilaurate, dropwise adding the fluorosilicone polymerization emulsion, and continuously reacting for 6-10h to obtain the modified epoxy resin.

2. The surface coating for aluminum alloy construction forms for preventing adhesion of concrete as claimed in claim 1, wherein the molar ratio of bisphenol A, epichlorohydrin, tetrabutylammonium bromide and sodium hydroxide in S1-S2 is 1: 6-12: 0.01-0.1: 2-4, 10-20m L of toluene is added per gram of bisphenol A, and the amount of bisphenol A in S3 is the same as that of bisphenol A in S1.

3. The surface coating for aluminum alloy construction panels for preventing adhesion of concrete as claimed in claim 1, wherein said vinylethoxydimethylsilane, hexafluorobutyl acrylate, emulsifier and potassium persulfate are used in the mass ratio of 1: 0.8-1.2: 0.1-0.3:0.05-0.2 in S4, 10-20m of L toluene is added per gram of vinylethoxydimethylsilane, and the emulsifier is a complex emulsifier obtained by mixing 3-allyloxy-2-1-propanesulfonic acid sodium salt, ethoxylated alkyl ether ammonium sulfate and triton.

4. The surface coating for building aluminum alloy formwork for preventing concrete adhesion according to claim 1, wherein the mass ratio of the bisphenol A epoxy resin, the fluorosilicone polymerized emulsion and the dibutyltin dilaurate in S5 is 1: 0.5-0.8: 0.01-0.05.

5. The surface coating for the building aluminum alloy formwork for preventing concrete adhesion according to claim 1, wherein the preparation method of the modified titanium dioxide comprises the following steps: adding a mixed solution of ethanol and water in a volume ratio of 1:0.05-0.2 into a reaction bottle, adding a silane coupling agent, uniformly stirring, heating to 40-50 ℃, adding nano titanium dioxide powder, stirring for 4-6h, carrying out reduced pressure concentration to remove the solvent, and drying the concentrate in an oven at 80-90 ℃ for 10-20h to obtain the modified titanium dioxide.

6. The method for preparing the surface coating for the building aluminum alloy formwork for preventing concrete adhesion according to claim 1, comprising the steps of:

adding the modified epoxy resin into ethyl acetate, adding N-methyl-2-pyrrolidone, stirring until the modified epoxy resin is completely dissolved, adding polytetrafluoroethylene powder and modified titanium dioxide into the solution, performing ultrasonic treatment for 20-60min to uniformly disperse the polytetrafluoroethylene powder and the modified titanium dioxide in the solution, adding a defoaming agent, stirring for 1-2h, adding a curing agent, and continuing stirring for 15-30min to obtain the surface coating for the building aluminum alloy template for preventing concrete adhesion.

7. The method for preparing the surface coating for the aluminum alloy formwork for construction for preventing concrete adhesion according to claim 6, wherein the mass ratio of the titanium dioxide powder to the silane coupling agent is 1:0.3-0.5, and 8-15m L of the mixed solution of ethanol and water is added per gram of the titanium dioxide powder.

8. The method for preparing the surface coating for the aluminum alloy formwork for construction for preventing adhesion of concrete according to claim 6, wherein the defoaming agent is polydimethylsiloxane and the curing agent is diaminodiphenylmethane.

Technical Field

The invention relates to the technical field of high polymer coatings, in particular to a surface coating for a building aluminum alloy template for preventing concrete adhesion and a preparation method thereof.

Background

The anti-sticking coating is a special coating, the surface of which is not easy to be adhered by other sticky substances or is easy to be removed after being adhered. The paint has the characteristics of extremely low surface energy, small friction coefficient, easy sliding and the like, so the paint has non-adhesiveness. The representative anti-sticking coatings at present mainly comprise the following types: organosilicon antisticking paint, fluorocarbon antisticking paint and inorganic ceramic antisticking paint.

Silicone release coatings are generally composed of silicone resins, epoxy resins, pigments, fillers and functional additives. Although the hydrophobic anti-sticking effect of the organosilicon anti-sticking coating is good, the hardness and the corrosion resistance of a coating film are poor. Patent CN201610035117.2 discloses a high thermal conductivity and high wear resistance silicone non-stick coating, which is composed of silicone modified polyester resin, ceramic resin, high temperature resistant pigment and filler, thermal conductive auxiliary agent and solvent, wherein the thermal conductive auxiliary agent is selected from one or more of graphene, carbon nanotube, diamond, graphite, aluminum powder and silver powder. Patent CN201510856346.6 discloses a high-thermal-conductivity non-stick pan coating, which mainly comprises graphene, silica sol, polyimide, methyl methacrylate, acrylic acid, methyltrimethoxysilane, fluorosilicone oil, titanium dioxide pigment, alumina wear-resistant powder, bentonite, deionized water and ethylene glycol butyl ether.

The basic component of the fluorocarbon anti-sticking coating is fluororesin, the main component used at present is Polytetrafluoroethylene (PTFE), the fluorocarbon anti-sticking coating can be continuously used for a long time at the temperature of below 260 ℃, the fluorocarbon anti-sticking coating does not dissolve or swell in any known solvent, oil and water do not act on the fluorocarbon anti-sticking coating even at high temperature, the fluorocarbon anti-sticking coating has excellent self-lubricating and hydrophobic and oleophobic properties, and the fluorocarbon anti-sticking coating is extremely easy to clean and is widely applied to the fields of non-stick coatings on the inner walls of cook. However, fluorocarbon release coatings still require the addition of various additives to increase the hardness, strength and heat dispersibility of their coatings, which makes the fluorocarbon release coatings costly.

Disclosure of Invention

The invention aims to provide a surface coating for a building aluminum alloy template for preventing concrete adhesion and a preparation method thereof, which can solve the following problems:

1. the anti-sticking performance, the chemical stability, the heat resistance, the mechanical performance and other performances of the coating are improved by blending the modified epoxy resin, the modified titanium dioxide and the polytetrafluoroethylene powder;

2. by modifying the epoxy resin, the epoxy resin not only has excellent adhesion to metal, but also has lower surface energy after film forming, thereby being beneficial to the anti-sticking performance of the coating.

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

the surface coating for the building aluminum alloy template for preventing concrete adhesion is characterized by comprising the following raw materials in parts by mass: 15-30 parts of modified epoxy resin, 5-15 parts of modified titanium dioxide, 15-25 parts of polytetrafluoroethylene powder, 30-50 parts of ethyl acetate, 1-5 parts of N-methyl-2-pyrrolidone, 0.1-3 parts of curing agent and 0.1-3 parts of defoaming agent;

the preparation method of the surface coating for the building aluminum alloy template for preventing the concrete adhesion comprises the following steps:

adding the modified epoxy resin into ethyl acetate, adding N-methyl-2-pyrrolidone, stirring until the modified epoxy resin is completely dissolved, adding polytetrafluoroethylene powder and modified titanium dioxide into the solution, performing ultrasonic treatment for 20-60min to uniformly disperse the polytetrafluoroethylene powder and the modified titanium dioxide in the solution, adding a defoaming agent, stirring for 1-2h, adding a curing agent, and continuing stirring for 15-30min to obtain the surface coating for the building aluminum alloy template for preventing concrete adhesion.

The modified epoxy resin is used as the main raw material of the coating, the main chain of the modified epoxy resin is bisphenol A epoxy resin, the modified epoxy resin is thermosetting resin with better comprehensive performance, has the advantages of good mechanical property, bonding property, good chemical stability, electric insulation, easy molding and processing, low price, easy acquisition and the like, the epoxy resin curing system contains polar groups such as epoxy group, hydroxyl group, ether bond, amine bond, ester bond and the like with extremely high activity, and the epoxy resin curing system has good bonding property for most metals and nonmetals except that polytetrafluoroethylene, polyethylene and polypropylene can not be directly bonded by the epoxy resin, so the epoxy resin has excellent adhesion effect on building aluminum alloy templates and high bonding strength, the cured epoxy resin has strong cohesive force and compact molecular structure, and the mechanical strength of the epoxy resin is higher than that of general thermosetting resins such as phenolic resin, unsaturated polyester and the like, the epoxy cured product also has excellent chemical stability, the performance of the epoxy cured product for resisting corrosion of various mediums such as alkali, acid, salt and the like is superior to that of thermosetting resin such as unsaturated polyester resin, phenolic resin and the like, and the epoxy cured product has a three-dimensional network structure and can resist the impregnation of oil and the like; in addition, by adding the modified titanium dioxide, the modified titanium dioxide can be effectively filled into pores formed by curing the epoxy resin to improve the impermeability of the epoxy resin, and a better corrosion prevention effect can be achieved.

Preferably, the preparation method of the modified epoxy resin is as follows:

s1, under the protection of nitrogen, adding bisphenol A and epichlorohydrin into a reaction bottle, heating to 70-80 ℃ under stirring, adding tetrabutylammonium bromide, reacting for 4-8h, and removing excessive epichlorohydrin by reduced pressure distillation after the reaction is finished to obtain an intermediate I, wherein the reaction equation is as follows:

s2, under the protection of nitrogen, adding the intermediate I and toluene into a reaction bottle, heating to 70-80 ℃ under stirring, adding sodium hydroxide, and reacting for 2-5h to obtain a solution I, wherein the reaction equation is as follows:

s3, adding bisphenol A into the first solution, heating to 75-80 ℃, reacting for 2-5h, cooling the reaction liquid to room temperature, adding disodium hydrogen phosphate to adjust the pH value to 6-7, filtering, washing the filtrate with deionized water for 3 times, and removing toluene by organic phase vacuum distillation to obtain bisphenol A epoxy resin, wherein the reaction equation is as follows:

s4, under the protection of nitrogen, dissolving hexafluorobutyl acrylate and vinyl ethoxy dimethyl silane in toluene, adding potassium persulfate, heating to 60-70 ℃ for reaction for 10-20h, carrying out reduced pressure distillation to remove toluene, adding water and an emulsifier into the reaction liquid, and continuously stirring for 2-3h to obtain a fluorine-silicon polymerization emulsion, wherein the reaction equation is as follows:

s5, adding bisphenol A epoxy resin into a reaction bottle under the protection of nitrogen, heating to 70-90 ℃, adding dibutyltin dilaurate, dropwise adding a fluorosilicone polymerization emulsion, and continuously reacting for 6-10h to obtain the modified epoxy resin, wherein the reaction equation is as follows:

hexafluorobutyl acrylate and vinyl ethoxy dimethylsilane are subjected to copolymerization reaction under the action of a catalyst to generate a fluorine-silicon polymer, alkoxy in the fluorine-silicon polymer is more active and can react with hydroxyl in a bisphenol A epoxy resin chain under the action of the catalyst, the fluorine-silicon polymer is introduced into the bisphenol A epoxy resin molecular chain, and the fluorine-containing branched chain is formed in the polymer by introducing the fluorine-silicon polymer, so that the surface energy of a coating film is favorably reduced, the anti-sticking property of the coating film is improved, and the bond energy of the silicon-silicon bond is far greater than that of a carbon-oxygen bond and a carbon-carbon bond by introducing the silicon-silicon bond, so that the polymer has higher strength and the high-temperature resistance of the coating is favorably.

Preferably, the molar ratio of the bisphenol A, the epichlorohydrin, the tetrabutylammonium bromide and the sodium hydroxide in the S1-S2 is 1: 6-12: 0.01-0.1: 2-4, 10-20m L of toluene is added per gram of the bisphenol A, and the amount of the bisphenol A in the S3 is the same as that of the bisphenol A in the S1.

Preferably, the mass ratio of the vinyl ethoxy dimethylsilane, the hexafluorobutyl acrylate, the emulsifier and the potassium persulfate in S4 is 1: 0.8-1.2: 0.1-0.3:0.05-0.2, 10-20m of L toluene is added into each gram of the vinyl ethoxy dimethylsilane, and the emulsifier is a composite emulsifier formed by mixing 3-allyloxy-2-1-propane sulfonic acid sodium salt, ethoxylated alkyl ether ammonium sulfate and triton.

Preferably, the mass ratio of the bisphenol A epoxy resin, the fluorosilicone polymerization emulsion and the dibutyltin dilaurate in S5 is 1: 0.5-0.8: 0.01-0.05.

Preferably, the preparation method of the modified titanium dioxide comprises the following steps: adding a mixed solution of ethanol and water in a volume ratio of 1:0.05-0.2 into a reaction bottle, adding a silane coupling agent, uniformly stirring, heating to 40-50 ℃, adding nano titanium dioxide powder, stirring for 4-6h, carrying out reduced pressure concentration to remove the solvent, and drying the concentrate in an oven at 80-90 ℃ for 10-20h to obtain the modified titanium dioxide.

Preferably, the mass ratio of the titanium dioxide powder to the silane coupling agent is 1:0.3-0.5, and 8-15m L of mixed solution of ethanol and water is added into each gram of titanium dioxide powder.

Preferably, the defoaming agent is polydimethylsiloxane, and the curing agent is diaminodiphenylmethane.

The invention has the beneficial effects that:

1. the modified epoxy resin is used as the main raw material of the coating, the main chain of the modified epoxy resin is bisphenol A epoxy resin, the modified epoxy resin is thermosetting resin with better comprehensive performance and has the advantages of good mechanical property, bonding property, good chemical stability, electric insulation, easy molding and processing and the like, the epoxy resin curing system contains polar groups such as epoxy groups, hydroxyl groups, ether bonds, amine bonds, ester bonds and the like with extremely high activity, and the epoxy resin has good bonding property on most of metals and nonmetals except that polytetrafluoroethylene, polyethylene and polypropylene can not be directly bonded by the epoxy resin, so the modified epoxy resin has excellent adhesion effect on building aluminum alloy templates, high bonding strength, strong cohesive force on the cured epoxy resin and compact molecular structure, so the mechanical strength of the modified epoxy resin is higher than that of general thermosetting resins such as phenolic resin, unsaturated polyester and the like, and an epoxy cured substance also has excellent chemical stability, the performance of the epoxy resin is superior to that of thermosetting resins such as unsaturated polyester resin, phenolic resin and the like in corrosion resistance to various media such as alkali, acid, salt and the like, so that the epoxy resin is used as an anti-corrosion primer in a large amount, and the epoxy resin condensate is in a three-dimensional network structure and can resist the impregnation of oil and the like; in addition, by adding the modified titanium dioxide, the modified titanium dioxide can be effectively filled into pores formed by curing the epoxy resin, the impermeability of the epoxy resin is improved, a better corrosion prevention effect can be achieved, the anti-sticking performance of the coating is improved by adding the polytetrafluoroethylene powder, and the polytetrafluoroethylene is a crystalline high-molecular polymer, has extremely low surface energy and stable chemical property, so that the anti-sticking performance of the coating is improved;

2. hexafluorobutyl acrylate and vinyl ethoxy dimethylsilane are subjected to copolymerization reaction under the action of a catalyst to generate a fluorine-silicon polymer, the fluorine-silicon polymer can be introduced into a bisphenol A epoxy resin molecular chain through active alkoxy in the fluorine-silicon polymer, and the fluorine-containing branched chain is arranged in the polymer through introducing the fluorine-silicon polymer, so that the surface energy of a coating formed film is favorably reduced, the anti-sticking property of the coating is improved, and the bond energy of the silicon-oxygen bond is far greater than that of a carbon-oxygen bond and a carbon-carbon bond through introducing the silicon-oxygen bond, so that the polymer has higher strength, and the high-temperature resistance of the coating is favorably improved.

Detailed Description

The technical solutions of the present invention will be described clearly and completely with reference to the following embodiments, and it should be understood that the described embodiments are only a part of the embodiments of the present invention, and not all of the 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.