阅读说明：本技术 一种反射隔热涂层及其制备方法 (Reflective heat-insulating coating and preparation method thereof ) 是由 林紫薇 于 2021-08-17 设计创作，主要内容包括：本发明公开了一种反射隔热涂层及其制备方法,涉及新材料领域。本发明首先将羟基聚醚聚二甲基硅氧烷与双氰胺反应经五氧化二磷酯化成改性聚硅氧烷,然后通过三羟甲基丙烷和豆油的醇解反应,将豆油羟基化生成甘油单酯,再与聚酰胺进行酯化反应合成植物油基聚酯多元醇,然后和异佛尔酮二异异氰酸酯进行缩聚反应,将异氰酸酯嵌接入醇酸树脂里,合成改性醇酸树脂,再用改性聚硅氧烷对改性醇酸树脂进行改性得硅氧烷改性醇酸树脂,即反射隔热涂层。本发明制备的反射隔热涂层具有隔热、阻燃、吸水、抗菌驱虫的作用。(The invention discloses a reflective heat-insulating coating and a preparation method thereof, and relates to the field of new materials. The preparation method comprises the steps of firstly reacting hydroxyl polyether polydimethylsiloxane with dicyandiamide, esterifying phosphorus pentoxide to form modified polysiloxane, hydroxylating soybean oil to form monoglyceride through alcoholysis reaction of trimethylolpropane and soybean oil, then performing esterification reaction on the monoglyceride and polyamide to synthesize vegetable oil-based polyester polyol, performing polycondensation reaction on the vegetable oil-based polyester polyol and isophorone diisocyanate, embedding isocyanate into alkyd resin, synthesizing modified alkyd resin, and modifying the modified alkyd resin with the modified polysiloxane to obtain siloxane modified alkyd resin, namely the reflective heat-insulation coating. The reflective heat-insulation coating prepared by the invention has the functions of heat insulation, flame retardance, water absorption, antibiosis and insect expelling.)

1. The reflective heat-insulating coating and the preparation method thereof are characterized by comprising the following raw materials in parts by weight: 70-100 parts of siloxane modified alkyd resin and 10-15 parts of curing agent.

2. A reflective thermal barrier coating according to claim 1, wherein: the siloxane modified alkyd resin comprises modified polysiloxane and modified alkyd resin.

3. A reflective thermal barrier coating according to claim 2, wherein: the modified polysiloxane is prepared by reacting hydroxyl polyether polydimethylsiloxane with dicyandiamide and esterifying by phosphorus pentoxide.

4. A reflective thermal barrier coating according to claim 2, wherein: the modified alkyd resin is synthesized by carrying out alcoholysis reaction on trimethylolpropane and soybean oil, hydroxylating the soybean oil to generate monoglyceride, carrying out esterification reaction on the monoglyceride and polyamide to synthesize vegetable oil-based polyester polyol, and carrying out polycondensation reaction on the vegetable oil-based polyester polyol and isophorone diisocyanate.

5. A reflective thermal barrier coating according to claim 1, wherein: the curing agent is one of vinyl triamine and m-phenylenediamine.

6. A reflective heat insulation coating and a preparation method thereof are characterized by comprising the following steps:

(1) preparation of modified polysiloxane: reacting hydroxyl polyether polydimethylsiloxane with dicyandiamide, and esterifying the reaction product by phosphorus pentoxide to obtain modified polysiloxane;

(2) preparation of vegetable oil-based polyester polyol: hydroxylating soybean oil to generate monoglyceride through alcoholysis reaction of trimethylolpropane and the soybean oil, and then carrying out esterification reaction on the monoglyceride and polyamide to expand molecular weight and increase molecular chains to synthesize vegetable oil-based polyester polyol;

(3) preparing modified alkyd resin: carrying out polycondensation reaction on vegetable oil-based polyester polyol and isophorone diisocyanate, and embedding isocyanate into alkyd resin to synthesize modified alkyd resin;

(4) preparing a reflective heat-insulating coating: the modified polysiloxane, the modified alkyd resin, the curing agent m-phenylenediamine and the sulfonic acid ions are heated and stirred to react to prepare the reflective heat-insulating coating.

7. The reflective thermal barrier coating and the method of making the same according to claim 6, wherein: in the step (1): putting aminopropyltriethoxysilane and deionized water in a flask in an ice-water bath according to a mass ratio of 1: 4-1: 5, dropwise adding dilute acetic acid to adjust the pH value to 4-5, uniformly stirring for 20-30 min to hydrolyze the mixture to obtain a colorless transparent liquid A, gradually heating to room temperature, adding a sodium hydroxide solution which is 0.1-0.2 times the mass of the aminopropyltriethoxysilane to adjust the pH value to 8-9 into the colorless transparent liquid A, adding calcium carbonate which is 0.03-0.05 times the mass of the aminopropyltriethoxysilane as a buffering agent to protect silicon hydroxyl, carrying out a polycondensation reaction for 2-2.5 hours to obtain a milky white liquid B, adding dicyandiamide which is 2-3 times the mass of the milky white liquid B into the milky white liquid B, uniformly mixing and stirring the colorless transparent liquid A and the milky white liquid B in a three-neck flask, fixing the colorless transparent liquid A and the milky white liquid B in a constant-temperature water bath by using an iron frame, keeping the temperature of the pot at 50-60 ℃, and carrying out condensation reflux for 50-60 min under the protection of nitrogen, adding phosphorus pentoxide with the mass being 3-4 times that of aminopropyltriethoxysilane into the reaction kettle, continuously stirring the mixture for 50-60 min in the reaction process, and volatilizing impurities to obtain the modified polysiloxane.

8. The reflective thermal barrier coating and the method of making the same according to claim 6, wherein: in the step (2): under the protection of nitrogen, adding vegetable oil, trimethylolpropane and lithium hydroxide into a four-neck flask provided with a condenser pipe, a stirrer and a thermometer according to a mass ratio of 2:2: 1-3: 3:1 in sequence, slowly heating to 230-240 ℃ for reaction, adding phthalic anhydride, organic tin and xylene according to a mass ratio of 1:0.5: 0.05-1: 0.1:0.01 when the temperature is reduced to 150-160 ℃, adding a water separator to remove water generated in the esterification reaction, slowly heating to 230-240 ℃, keeping the temperature, stopping heating when the acid value of a system is 5-10 mgKOH/g, and distilling under reduced pressure to remove residual xylene to obtain the vegetable oil-based polyester polyol.

9. The reflective thermal barrier coating and the method of making the same according to claim 6, wherein: in the step (3): controlling the temperature to be 70-80 ℃, uniformly mixing and stirring isophorone diisocyanate, butyltin dilaurate, butanediol and dimethylolpropionic acid according to the mass ratio of 3:1:1: 0.5-5: 1:1:0.5, then mixing and stirring with vegetable oil-based polyester polyol until the mixture is dissolved, when the temperature is reduced to 50-60 ℃, adding acetone with the mass of 0.3-0.5 time that of isophorone diisocyanate to reduce the viscosity of a polymer, transferring a reactant into a dispersion barrel, adding chain extension while stirring at a high speed, and removing the acetone by reduced pressure distillation to obtain the modified alkyd resin.

10. The reflective thermal barrier coating and the method of making the same according to claim 6, wherein: in the step (4): the modified polysiloxane and the modified alkyd resin are uniformly mixed and stirred according to the mass ratio of 2: 3-2: 5, sulfonic acid ions which are 0.1-0.3 times of the mass of the modified alkyd resin are added for continuous stirring, the modified alkyd resin is transferred into a dispersing barrel, residual impurities are removed while high-speed stirring is carried out, and then the reflective heat-insulating coating is obtained after curing by using a curing agent m-phenylenediamine.

Technical Field

The invention relates to the technical field of new materials, in particular to a reflective heat-insulating coating and a preparation method thereof.

Background

The coating can change the components and the tissue structure of the surface of the material, so that the coating is widely applied to various industries, most coating technologies are applied to the industries such as microelectronics, sensors, aerospace and the like, the reflective heat-insulating coating prepared by the invention is applied to clothes worn in desert during walking, the environment in desert is severe, and the quantity of harmful snakes is too much, and the clothes can be quickly adapted to the dry environment in desert when being worn, effectively keep the harmful snakes away from human beings, absorb water molecules in atmosphere, make people feel moist, and effectively isolate a heat source and have flame retardant property when the temperature in desert is too high. Therefore, it is necessary to design a reflective thermal barrier coating that has water absorption and is antimicrobial and insect repellant.

Disclosure of Invention

The present invention is directed to a reflective thermal barrier coating and a method for preparing the same, which solve the problems of the prior art.

In order to solve the technical problems, the invention provides the following technical scheme: a reflective heat insulation coating and a preparation method thereof comprise the following raw materials in parts by weight:

70-100 parts of siloxane modified alkyd resin and 10-15 parts of auxiliary agent.

Preferably, the siloxane-modified alkyd resin comprises a modified polysiloxane, a modified alkyd resin.

Preferably, the modified polysiloxane is prepared by reacting hydroxyl polyether polydimethylsiloxane with dicyandiamide and esterifying by phosphorus pentoxide.

Preferably, the modified alkyd resin is synthesized by hydroxylating soybean oil to generate monoglyceride through alcoholysis reaction of trimethylolpropane and the soybean oil, then carrying out esterification reaction on the monoglyceride and polyamide to synthesize vegetable oil-based polyester polyol, and then carrying out polycondensation reaction on the vegetable oil-based polyester polyol and isophorone diisocyanate.

Preferably, the curing agent is one of vinyl triamine and m-phenylenediamine.

The invention provides a reflective heat insulation coating and a preparation method thereof, and the reflective heat insulation coating comprises the following specific steps:

(1) preparation of modified polysiloxane: reacting hydroxyl polyether polydimethylsiloxane with dicyandiamide, and esterifying the reaction product by phosphorus pentoxide to obtain modified polysiloxane;

(2) preparation of vegetable oil-based polyester polyol: hydroxylating soybean oil to generate monoglyceride through alcoholysis reaction of trimethylolpropane and the soybean oil, and then carrying out esterification reaction on the monoglyceride and polyamide to expand molecular weight and increase molecular chains to synthesize vegetable oil-based polyester polyol;

(3) preparing modified alkyd resin: carrying out polycondensation reaction on vegetable oil-based polyester polyol and isophorone diisocyanate, and embedding isocyanate into alkyd resin to synthesize modified alkyd resin;

(4) preparing a reflective heat-insulating coating: the modified polysiloxane, the modified alkyd resin, the curing agent m-phenylenediamine and the sulfonic acid ions are heated and stirred to react to prepare the reflective heat-insulating coating.

Preferably, in the step (1): putting aminopropyltriethoxysilane and deionized water in a flask in an ice-water bath according to a mass ratio of 1: 4-1: 5, dropwise adding dilute acetic acid to adjust the pH value to 4-5, uniformly stirring for 20-30 min to hydrolyze the mixture to obtain a colorless transparent liquid A, gradually heating to room temperature, adding a sodium hydroxide solution which is 0.1-0.2 times the mass of the aminopropyltriethoxysilane to adjust the pH value to 8-9 into the colorless transparent liquid A, adding calcium carbonate which is 0.03-0.05 times the mass of the aminopropyltriethoxysilane as a buffering agent to protect silicon hydroxyl, carrying out a polycondensation reaction for 2-2.5 hours to obtain a milky white liquid B, adding dicyandiamide which is 2-3 times the mass of the milky white liquid B into the milky white liquid B, uniformly mixing and stirring the colorless transparent liquid A and the milky white liquid B in a three-neck flask, fixing the colorless transparent liquid A and the milky white liquid B in a constant-temperature water bath by using an iron frame, keeping the temperature of the pot at 50-60 ℃, and carrying out condensation reflux for 50-60 min under the protection of nitrogen, adding phosphorus pentoxide with the mass being 3-4 times that of aminopropyltriethoxysilane into the reaction kettle, continuously stirring the mixture for 50-60 min in the reaction process, and volatilizing impurities to obtain the modified polysiloxane.

Preferably, in the step (2): under the protection of nitrogen, adding vegetable oil, trimethylolpropane and lithium hydroxide into a four-neck flask provided with a condenser pipe, a stirrer and a thermometer according to a mass ratio of 2:2: 1-3: 3:1 in sequence, slowly heating to 230-240 ℃ for reaction, adding phthalic anhydride, organic tin and xylene according to a mass ratio of 1:0.5: 0.05-1: 0.1:0.01 when the temperature is reduced to 150-160 ℃, adding a water separator to remove water generated in the esterification reaction, slowly heating to 230-240 ℃, keeping the temperature, stopping heating when the acid value of a system is 5-10 mgKOH/g, and distilling under reduced pressure to remove residual xylene to obtain the vegetable oil-based polyester polyol.

Preferably, in the step (3): controlling the temperature to be 70-80 ℃, uniformly mixing and stirring isophorone diisocyanate, butyltin dilaurate, butanediol and dimethylolpropionic acid according to the mass ratio of 3:1:1: 0.5-5: 1:1:0.5, then mixing and stirring with vegetable oil-based polyester polyol until the mixture is dissolved, when the temperature is reduced to 50-60 ℃, adding acetone with the mass of 0.3-0.5 time that of isophorone diisocyanate to reduce the viscosity of a polymer, transferring a reactant into a dispersion barrel, adding chain extension while stirring at a high speed, and removing the acetone by reduced pressure distillation to obtain the modified alkyd resin.

Preferably, in the step (4): the modified polysiloxane and the modified alkyd resin are uniformly mixed and stirred according to the mass ratio of 2: 3-2: 5, sulfonic acid ions which are 0.1-0.3 times of the mass of the modified alkyd resin are added for continuous stirring, the modified alkyd resin is transferred into a dispersing barrel, residual impurities are removed while high-speed stirring is carried out, and then the reflective heat-insulating coating is obtained after curing by using a curing agent m-phenylenediamine.

Compared with the prior art, the invention has the following beneficial effects:

the reflective heat-insulating coating prepared by the invention is applied to cotton fabric clothes worn in walking desert.

Firstly, hydroxyl polyether polydimethylsiloxane and dicyandiamide react and are esterified into modified polysiloxane through phosphorus pentoxide, when the modified polysiloxane is subjected to spontaneous combustion at an overhigh temperature, phosphoryl in the modified polysiloxane can be decomposed to generate polyphosphoric acid which has a strong phosphorylation effect on cotton cellulose in the combustion process, so that the cotton cellulose forms a viscous flow layer and has a heat insulation effect, the polysiloxane in the modified polysiloxane is pyrolyzed to generate amorphous silicon dioxide and glassy carbon, an expansion type residual carbon layer which is compact in appearance and loose in interior is formed under the action of heat, and the cotton cellulose is expanded to form coke under the action of blowing in flame, so that the heat insulation effect is achieved, the thermal stability of the cotton fabric is improved, the carbonization is promoted, and the flame retardance is improved.

And then, hydroxylating the soybean oil to generate monoglyceride through alcoholysis reaction of trimethylolpropane and the soybean oil, then carrying out esterification reaction on the monoglyceride and polyamide to expand molecular weight and increase molecular chains to synthesize vegetable oil-based polyester polyol, then carrying out polycondensation reaction on the vegetable oil-based polyester polyol and isophorone diisocyanate, embedding isocyanate into alkyd resin to synthesize modified alkyd resin, and modifying the modified alkyd resin by using modified polysiloxane to obtain the siloxane modified alkyd resin.

The vegetable oil-based polyester polyol contains a large amount of unsaturated fatty acid chains, unsaturated carbon-carbon double bonds in fatty acid can generate oxidation with air to form hydroperoxide, the hydroperoxide is decomposed to generate alkyl free radicals, the alkyl free radicals interact with each other to combine molecules with each other to form a macromolecular reticular structure, the toughness of the modified alkyd resin can be enhanced, the wear resistance is improved, after the unsaturated fatty acid on the side chain of the modified alkyd resin is subjected to oxygen absorption and crosslinking, a dense crosslinking structure can be formed between soft and hard segments of the modified alkyd resin, the heat resistance of the modified alkyd resin is improved, the modified polysiloxane and the modified alkyd resin have good compatibility, the micro-phase separation of a system can be promoted, the hydrogen bonding effect between hard segments of the siloxane modified alkyd resin is favorably strengthened, a better physical crosslinking structure is favorably formed by the system, and the tensile strength is increased, the toughness is improved, particularly, the cross-linking structure between the soft segments of the siloxane modified alkyd resin is easy to break at high temperature, the thermal decomposition rate begins to increase, good heat resistance is presented, when the cross-linking degree of the siloxane modified alkyd resin is higher, the mutual fusion of emulsion particles during film forming is poor due to the structure of the cross-linking density of the system, the compactness of an adhesive film is reduced, water molecules are easy to invade, the prepared coating can effectively adsorb the water molecules in the air, so that the body of a person can not lack water when the person walks in a desert, but feels cool and moist, and the siloxane modified alkyd resin also contains a large number of hydrophilic ether bonds, so that the water absorption of the resin can be effectively improved.

The sulfonic acid ion exchange modified alkyd resin is used, hydrogen ions in the modified alkyd resin can carry positive charges with carbon atoms connected with methyl groups in modified polysiloxane, when bonds with quaternary carbon atoms are broken, another hydrogen ion in the modified alkyd resin can enable the carbon atoms to carry positive charges, the modified alkyd resin can absorb water and combine with water to release hydrogen ions to generate terpineol, hydroxyl groups connected with the methyl groups in the terpineol are catalyzed in the resin to generate terpineol, guanidyl in the modified polysiloxane can be grafted with the terpineol to adsorb surfaces of microorganisms with negative charges, the action of cell lysozyme is hindered, the surface structure of cells is denatured and damaged, the growth of bacteria is inhibited, an antibacterial effect is achieved, meanwhile, special fragrance can be emitted, insects in desert are driven to be far away, and personal safety is guaranteed.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious 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.

The invention provides the technical scheme that: a reflective heat insulation coating and a preparation method thereof comprise the following raw materials in parts by weight:

70-100 parts of siloxane modified alkyd resin and 10-15 parts of auxiliary agent.

Preferably, the siloxane-modified alkyd resin comprises a modified polysiloxane, a modified alkyd resin.

Preferably, the modified polysiloxane is prepared by reacting hydroxyl polyether polydimethylsiloxane with dicyandiamide and esterifying by phosphorus pentoxide.

Preferably, the modified alkyd resin is synthesized by hydroxylating soybean oil to generate monoglyceride through alcoholysis reaction of trimethylolpropane and the soybean oil, then carrying out esterification reaction on the monoglyceride and polyamide to synthesize vegetable oil-based polyester polyol, and then carrying out polycondensation reaction on the vegetable oil-based polyester polyol and isophorone diisocyanate.

Preferably, the curing agent is one of vinyl triamine and m-phenylenediamine.

The invention provides a reflective heat insulation coating and a preparation method thereof, and the reflective heat insulation coating comprises the following specific steps:

(1) preparation of modified polysiloxane: reacting hydroxyl polyether polydimethylsiloxane with dicyandiamide, and esterifying the reaction product by phosphorus pentoxide to obtain modified polysiloxane;

(2) preparation of vegetable oil-based polyester polyol: hydroxylating soybean oil to generate monoglyceride through alcoholysis reaction of trimethylolpropane and the soybean oil, and then carrying out esterification reaction on the monoglyceride and polyamide to expand molecular weight and increase molecular chains to synthesize vegetable oil-based polyester polyol;

(3) preparing modified alkyd resin: carrying out polycondensation reaction on vegetable oil-based polyester polyol and isophorone diisocyanate, and embedding isocyanate into alkyd resin to synthesize modified alkyd resin;

(4) preparing a reflective heat-insulating coating: the modified polysiloxane, the modified alkyd resin, the curing agent m-phenylenediamine and the sulfonic acid ions are reacted together to prepare the reflective heat-insulating coating.

Preferably, in the step (1): putting aminopropyltriethoxysilane and deionized water in a flask in an ice-water bath according to a mass ratio of 1: 4-1: 5, dropwise adding dilute acetic acid to adjust the pH value to 4-5, uniformly stirring for 20-30 min to hydrolyze the mixture to obtain a colorless transparent liquid A, gradually heating to room temperature, adding a sodium hydroxide solution which is 0.1-0.2 times the mass of the aminopropyltriethoxysilane to adjust the pH value to 8-9 into the colorless transparent liquid A, adding calcium carbonate which is 0.03-0.05 times the mass of the aminopropyltriethoxysilane as a buffering agent to protect silicon hydroxyl, carrying out a polycondensation reaction for 2-2.5 hours to obtain a milky white liquid B, adding dicyandiamide which is 2-3 times the mass of the milky white liquid B into the milky white liquid B, uniformly mixing and stirring the colorless transparent liquid A and the milky white liquid B in a three-neck flask, fixing the colorless transparent liquid A and the milky white liquid B in a constant-temperature water bath by using an iron frame, keeping the temperature of the pot at 50-60 ℃, and carrying out condensation reflux for 50-60 min under the protection of nitrogen, adding phosphorus pentoxide with the mass being 3-4 times that of aminopropyltriethoxysilane into the reaction kettle, continuously stirring the mixture for 50-60 min in the reaction process, and volatilizing impurities to obtain the modified polysiloxane.

Preferably, in the step (2): under the protection of nitrogen, adding vegetable oil, trimethylolpropane and lithium hydroxide into a four-neck flask provided with a condenser pipe, a stirrer and a thermometer according to a mass ratio of 2:2: 1-3: 3:1 in sequence, slowly heating to 230-240 ℃ for reaction, adding phthalic anhydride, organic tin and xylene according to a mass ratio of 1:0.5: 0.05-1: 0.1:0.01 when the temperature is reduced to 150-160 ℃, adding a water separator to remove water generated in the esterification reaction, slowly heating to 230-240 ℃, keeping the temperature, stopping heating when the acid value of a system is 5-10 mgKOH/g, and distilling under reduced pressure to remove residual xylene to obtain the vegetable oil-based polyester polyol.

Preferably, in the step (3): controlling the temperature to be 70-80 ℃, uniformly mixing and stirring isophorone diisocyanate, butyltin dilaurate, butanediol and dimethylolpropionic acid according to the mass ratio of 3:1:1: 0.5-5: 1:1:0.5, then mixing and stirring with vegetable oil-based polyester polyol until the mixture is dissolved, when the temperature is reduced to 50-60 ℃, adding acetone with the mass of 0.3-0.5 time that of isophorone diisocyanate to reduce the viscosity of a polymer, transferring a reactant into a dispersion barrel, adding chain extension while stirring at a high speed, and removing the acetone by reduced pressure distillation to obtain the modified alkyd resin.

Preferably, in the step (4): the modified polysiloxane and the modified alkyd resin are uniformly mixed and stirred according to the mass ratio of 2: 3-2: 5, sulfonic acid ions which are 0.1-0.3 times of the mass of the modified alkyd resin are added for continuous stirring, the modified alkyd resin is transferred into a dispersing barrel, residual impurities are removed while high-speed stirring is carried out, and then the reflective heat-insulating coating is obtained after curing by using a curing agent m-phenylenediamine.

Example 1: reflective heat-insulating coating

A reflective heat insulation coating and a preparation method thereof comprise the following raw materials in parts by weight:

70 parts of siloxane modified alkyd resin and 10 parts of auxiliary agent.

A reflective heat insulation coating and a preparation method thereof comprise the following specific steps:

(1) preparation of modified polysiloxane: reacting hydroxyl polyether polydimethylsiloxane with dicyandiamide, and esterifying the reaction product by phosphorus pentoxide to obtain modified polysiloxane;

(2) preparation of vegetable oil-based polyester polyol: hydroxylating soybean oil to generate monoglyceride through alcoholysis reaction of trimethylolpropane and the soybean oil, and then carrying out esterification reaction on the monoglyceride and polyamide to expand molecular weight and increase molecular chains to synthesize vegetable oil-based polyester polyol;

(3) preparing modified alkyd resin: carrying out polycondensation reaction on vegetable oil-based polyester polyol and isophorone diisocyanate, and embedding isocyanate into alkyd resin to synthesize modified alkyd resin;

(4) preparing a reflective heat-insulating coating: the modified polysiloxane, the modified alkyd resin, the curing agent m-phenylenediamine and the sulfonic acid ions are reacted together to prepare the reflective heat-insulating coating.

Preferably, in the step (1): putting aminopropyltriethoxysilane and deionized water in a flask according to the mass ratio of 1:4 in an ice-water bath, dropwise adding diluted acetic acid to adjust the pH value to 4, uniformly stirring for 20min to hydrolyze the mixture to obtain colorless transparent liquid A, gradually heating to room temperature, adding a sodium hydroxide solution which is 0.1 time of the mass of the aminopropyltriethoxysilane in the colorless transparent liquid A to adjust the pH value to 8, adding calcium carbonate which is 0.03 time of the mass of the aminopropyltriethoxysilane in a buffering agent to protect silicon hydroxyl, carrying out polycondensation reaction for 2 hours to obtain milky liquid B, adding dicyandiamide in the milky liquid B in an amount which is 2 times of the mass of the aminopropyltriethoxysilane, uniformly mixing and stirring the colorless transparent liquid A and the milky liquid B in a three-neck flask, fixing the colorless transparent liquid A and the milky liquid B in a constant-temperature water bath kettle by using an iron frame, keeping the temperature in the kettle at 50 ℃, carrying out condensation reflux for 50min under the protection of nitrogen, adding phosphorus pentoxide which is 3 times of the mass of the aminopropyltriethoxysilane in the three-neck flask, continuously stirring for 50min in the reaction process, and volatilizing impurities to obtain the modified polysiloxane.

Preferably, in the step (2): under the protection of nitrogen, adding vegetable oil, trimethylolpropane and lithium hydroxide into a four-neck flask provided with a condenser pipe, a stirrer and a thermometer according to the mass ratio of 2:2:1 in sequence, slowly heating to 230 ℃ for reaction, adding phthalic anhydride, organic tin and xylene according to the mass ratio of 1:0.5:0.05 into the flask until the temperature is reduced to 150 ℃, adding a water separator to remove water generated by esterification reaction, slowly heating to 230 ℃, keeping the temperature, stopping heating when the acid value of a system is 5mgKOH/g, and removing residual xylene through reduced pressure distillation to obtain the vegetable oil-based polyester polyol.

Preferably, in the step (3): controlling the temperature to be below 70 ℃, mixing and stirring isophorone diisocyanate, butyltin dilaurate, butanediol and dimethylolpropionic acid uniformly according to the mass ratio of 3:1:1:0.5, mixing and stirring with vegetable oil-based polyester polyol until the mixture is dissolved, adding acetone with the mass of 0.3 time that of isophorone diisocyanate to reduce the viscosity of a polymer when the temperature is reduced to be below 50 ℃, transferring a reactant into a dispersing barrel, adding chain extension while stirring at a high speed, and removing the acetone through reduced pressure distillation to obtain the modified alkyd resin.

Preferably, in the step (4): the modified polysiloxane and the modified alkyd resin are mixed and stirred uniformly according to the mass ratio of 2:3, sulfonic acid ions which are 0.1 time of the mass of the modified alkyd resin are added for continuous stirring, the mixture is transferred into a dispersing barrel, residual impurities are removed while high-speed stirring is carried out, and then the reflective heat-insulating coating is obtained after curing agent m-phenylenediamine is used for curing.

Example 2: reflective heat-insulating coating II

A reflective heat insulation coating and a preparation method thereof comprise the following raw materials in parts by weight:

100 parts of siloxane modified alkyd resin and 15 parts of auxiliary agent.

A reflective heat insulation coating and a preparation method thereof comprise the following specific steps:

(1) preparation of modified polysiloxane: reacting hydroxyl polyether polydimethylsiloxane with dicyandiamide, and esterifying the reaction product by phosphorus pentoxide to obtain modified polysiloxane;

(2) preparation of vegetable oil-based polyester polyol: hydroxylating soybean oil to generate monoglyceride through alcoholysis reaction of trimethylolpropane and the soybean oil, and then carrying out esterification reaction on the monoglyceride and polyamide to expand molecular weight and increase molecular chains to synthesize vegetable oil-based polyester polyol;

(3) preparing modified alkyd resin: carrying out polycondensation reaction on vegetable oil-based polyester polyol and isophorone diisocyanate, and embedding isocyanate into alkyd resin to synthesize modified alkyd resin;

(4) preparing a reflective heat-insulating coating: the modified polysiloxane, the modified alkyd resin, the curing agent m-phenylenediamine and the sulfonic acid ions are reacted together to prepare the reflective heat-insulating coating.

Preferably, in the step (1): putting aminopropyltriethoxysilane and deionized water in a flask in an ice-water bath according to the mass ratio of 1:5, dropwise adding dilute acetic acid to adjust the pH value to 5, uniformly stirring for 30min to hydrolyze the mixture to obtain colorless transparent liquid A, gradually heating to room temperature, adding a sodium hydroxide solution which is 0.2 times of the mass of the aminopropyltriethoxysilane in the colorless transparent liquid A to adjust the pH value to 9, adding calcium carbonate which is 0.05 times of the mass of the aminopropyltriethoxysilane in a buffer to protect silicon hydroxyl, carrying out polycondensation reaction for 2.5 h to obtain milky liquid B, adding dicyandiamide which is 3 times of the mass of the milky liquid B into the milky liquid B, uniformly mixing and stirring the colorless transparent liquid A and the milky liquid B in a three-neck flask, fixing the colorless transparent liquid A and the milky liquid B in a constant-temperature water bath kettle by using an iron frame, keeping the temperature in the kettle at 60 ℃, carrying out condensation reflux for 60min under the protection of nitrogen, adding phosphorus pentoxide which is 4 times of the mass of the aminopropyltriethoxysilane into the three-neck flask, continuously stirring for 60min in the reaction process, and volatilizing impurities to obtain the modified polysiloxane.

Preferably, in the step (2): under the protection of nitrogen, adding vegetable oil, trimethylolpropane and lithium hydroxide into a four-neck flask provided with a condenser pipe, a stirrer and a thermometer according to the mass ratio of 3:3:1 in sequence, slowly heating to 240 ℃ for reaction, adding phthalic anhydride, organic tin and xylene according to the mass ratio of 1:0.1:0.01 when the temperature is reduced to 160 ℃, adding a water separator to remove water generated in the esterification reaction, slowly heating to 240 ℃, keeping the temperature, stopping heating when the acid value of the system is 10mgKOH/g, and removing residual xylene through reduced pressure distillation to obtain the vegetable oil-based polyester polyol.

Preferably, in the step (3): controlling the temperature to be 80 ℃, mixing and stirring isophorone diisocyanate, butyltin dilaurate, butanediol and dimethylolpropionic acid uniformly according to the mass ratio of 5:1:1:0.5, mixing and stirring with vegetable oil-based polyester polyol until the mixture is dissolved, adding acetone with the mass of 0.5 time that of isophorone diisocyanate to reduce the viscosity of a polymer when the temperature is reduced to 60 ℃, transferring a reactant into a dispersing barrel, adding chain extension while stirring at a high speed, and removing the acetone through reduced pressure distillation to obtain the modified alkyd resin.

Preferably, in the step (4): the modified polysiloxane and the modified alkyd resin are mixed and stirred uniformly according to the mass ratio of 2:5, sulfonic acid ions which are 0.3 times of the mass of the modified alkyd resin are added for continuous stirring, the mixture is transferred into a dispersing barrel, residual impurities are removed while high-speed stirring is carried out, and then the reflective heat-insulating coating is obtained after curing agent m-phenylenediamine is used for curing.

Comparative example 1:

preparation of a common coating: heating, mixing and stirring the resin and the auxiliary agent uniformly, and curing by using a curing agent to obtain the common coating.

Comparative example 2:

comparative example 2 was formulated as in example 1. The reflective thermal barrier coating was prepared by a method different from that of example 1 only in that the preparation of step (1) was not performed, and the remaining preparation steps were the same as those of example 1.

Comparative example 3:

the formulation of ratio 3 was the same as in example 1. The reflective thermal barrier coating was prepared by a method different from that of example 1 only in that the preparation of step (3) was not performed, and the remaining preparation steps were the same as those of example 1.

Test example 1

The flame retardancy test was performed on example 1, comparative example 1, and comparative example 2, respectively, the pressure and air flow of the surrounding environment were controlled, the baking was performed with the same degree of flame, and the degree of coating breakage was observed as follows:

	degree of breakage (%)
		Example 1	30％
Comparative example 1	80％
		Comparative example 2	50％

As can be seen from the above data, the damage degree of example 1 is the lowest, the cross-linked structure between the soft segments of the siloxane-modified alkyd resin is easily broken at high temperature, the thermal decomposition rate begins to increase, and good heat resistance is exhibited, when the modified polysiloxane is over-high in temperature and spontaneously ignites, the phosphoryl group in the modified polysiloxane can be decomposed to generate polyphosphoric acid which has strong phosphorylation effect on cotton cellulose in the combustion process, so that the cotton cellulose forms a viscous flow layer and has a heat insulation effect, the polysiloxane in the modified polysiloxane is pyrolyzed to generate amorphous silicon dioxide and glassy carbon, an expansion type residual carbon layer with compact appearance and loose interior is formed under the action of heat, and has the function of blowing in flame to expand the cotton cellulose fiber to form coke, therefore, the heat insulation effect is achieved, the thermal stability of the cotton fabric is improved, the carbonization is promoted, and the flame retardance is improved.

Test example 2

The water absorption performance test is respectively carried out on the example 1, the comparative example 1 and the comparative example 3, the three coatings are soaked by water with the same quality and the same components under normal temperature and normal pressure, and the measurement data are as follows:

it can be seen from the above that the coating of example 1 has the highest water absorption, and the coating of comparative example 2 has the lowest water absorption, and the comparative example 1 is the lowest because when the crosslinking degree of the siloxane modified alkyd resin is higher, the structure of the crosslinking density of the system can cause the emulsion particles to have poor mutual fusion during film forming, so that the compactness of the adhesive film is reduced, water molecules are easy to invade instead, the prepared coating can effectively adsorb water molecules in the air, so that people can feel cool and moist without water shortage when walking in desert, and the siloxane modified alkyd resin also contains a large amount of hydrophilic ether bonds, so that the water absorption of the resin can be effectively improved.

It is noted that, herein, relational terms such as first and second, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus.

Finally, it should be noted that: although the present invention has been described in detail with reference to the foregoing embodiments, it will be apparent to those skilled in the art that changes may be made in the embodiments and/or equivalents thereof without departing from the spirit and scope of the invention. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.