A kind of heat-insulating coating for exterior wall and preparation method thereof

Abstract

The present invention relates to a coating for heat-insulating exterior walls and a preparation method thereof. The present invention creatively modifies and compounds the heat-insulating filler so that the water-based coating formed after mixing it with other components has better heat-insulating performance. On the one hand, the present invention utilizes TMCS for treatment in the preparation of silica aerogel, and a large number of methyl groups are grafted on the surface, which can better maintain its inherent performance. On the other hand, 3-aminopropyltrihydroxysilane is used to modify the hollow glass microspheres, and more hydrophilic groups are grafted on the surface to enhance its hydrophilic ability. Finally, polyvinyl alcohol is used as a bridging substance to compound the grafted silica aerogel and the hollow glass microspheres to form an inorganic-organic-inorganic filler. In actual application, not only the strength of the heat-insulating filler itself is enhanced, and it is not easy to break even under high-speed dispersion, but it can also be well dispersed in the water-based coating to form a uniform system.

Description

Technical Field

[0001] The present invention belongs to the technical field of thermal insulation coatings, and in particular relates to a thermal insulation coating for exterior walls and a preparation method thereof. Background Art

[0002] Thermal insulation paint is a kind of paint that can block heat. It is mainly composed of film-forming substances, dispersion media, thermal insulation fillers and additives, and is widely applied on the surface of exterior walls.

[0003] With excellent thermal insulation performance, the current thermal insulation fillers are basically hollow glass microspheres, silica aerogels and other substances. At the same time, multiple thermal insulation fillers are often used in combination to achieve better thermal insulation effects. However, hollow glass microspheres and silica aerogels still have great disadvantages in practical applications, which limit their thermal insulation performance. On the one hand, hollow glass microspheres and silica aerogels are both low-strength materials with high brittleness, which leads to easy breakage and other phenomena when preparing thermal insulation coatings under high-speed dispersion, thereby forming cavities inside the system and causing heat convection. On the other hand, silica aerogels are mostly hydrophobic substances, which have poor dispersibility in water-based coatings and are prone to stratification, uneven mixing and other problems. Solvent-based coatings are not environmentally friendly and are not the technological development trend of coatings.

[0004] Therefore, the current thermal insulation coatings still have many defects and are in urgent need of improvement. Summary of the Invention

[0005] In response to the problems existing in the prior art, the present invention aims to provide a thermal insulation coating for exterior walls and a preparation method thereof. The present invention creatively modifies and compounds the thermal insulation filler so that the water-based coating formed after mixing it with other components has better thermal insulation performance. On the one hand, the present invention utilizes TMCS to treat the silica aerogel in the preparation, grafting a large number of methyl groups on the surface to better maintain its inherent properties. On the other hand, the present invention utilizes 3-aminopropyltrihydroxysilane to modify the hollow glass microspheres, grafting more hydrophilic groups on the surface to enhance their hydrophilicity. Finally, polyvinyl alcohol is used as a bridging substance to composite the grafted silica aerogel and hollow glass microspheres to form an inorganic-organic-inorganic filler. In practical application, this not only enhances the strength of the thermal insulation filler itself and is not easily broken even under high-speed dispersion, but also can be well dispersed in the water-based coating to form a uniform system.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A thermal insulation coating for exterior walls is prepared from 90-100 parts by weight of a styrene-acrylic emulsion, 60-80 parts by weight of deionized water, 25-30 parts by weight of a composite thermal insulation filler, 10-15 parts by weight of titanium dioxide, 2-3 parts by weight of a defoaming agent, 2-3 parts by weight of propylene glycol, and 2-3 parts by weight of a film-forming aid.

[0008] As a preferred technical solution of the present invention, the solid content of the styrene-acrylic emulsion is 45-50%.

[0009] As a preferred technical solution of the present invention, the composite thermal insulation filler is prepared by the following steps:

[0010] Step a: adding tetraethoxysilane and anhydrous ethanol to deionized water, stirring for 5-10 minutes to mix, and then adjusting the pH to 3-4 with hydrochloric acid solution to obtain solution a;

[0011] Step b: stirring solution a at room temperature for 24-28 hours to react, then adjusting the pH to 7-8 with aqueous ammonia, standing for 10-12 hours, and filtering to obtain wet gel a;

[0012] Step c: adding anhydrous ethanol to the wet gel a until it is completely immersed, then aging at 50-60° C. for 24-26 hours, filtering to obtain a wet gel b, and finally adding a mixed solution of trimethylchlorosilane and n-hexane until it is completely immersed, standing for 48-72 hours, and filtering to obtain a wet gel c;

[0013] Step d: washing the wet gel c with n-hexane 5-8 times, and then vacuum drying at 50-60° C. until constant weight is obtained to obtain a hydrophobically modified silica aerogel;

[0014] Step e: adding 10-15 parts by weight of polyvinyl alcohol and 0.5-1 parts by weight of p-toluenesulfonic acid to 170-180 parts by weight of deionized water, stirring at 95° C. until completely dissolved, then adding 70-80 parts by weight of modified hollow glass microspheres and 25-30 parts by weight of hydrophobically modified silica aerogel, stirring at 95-100° C. for 2-3 hours to obtain solution b;

[0015] Step f: Cool solution b naturally to room temperature, filter, remove the filtrate, wash with n-hexane, and then vacuum dry at 50-60° C. until constant weight is reached. The preparation is completed.

[0016] Furthermore, the molar ratio of deionized water, tetraethoxysilane and anhydrous ethanol in step a is 4-5:1-2:7-9.

[0017] Furthermore, the mass fraction of the hydrochloric acid solution in step a is 20-30%.

[0018] Furthermore, the mass fraction of the ammonia water in step b is 25-30%.

[0019] Furthermore, the mixed solution of trimethylchlorosilane and n-hexane in step c is prepared according to a volume ratio of trimethylchlorosilane to n-hexane of 1-1.5:8-10.

[0020] Furthermore, the modified hollow glass microspheres in step e are prepared by the following steps:

[0021] Step A: 8-12 parts by weight of 3-aminopropyltrihydroxysilane and 100-120 parts by weight of anhydrous ethanol are mixed, and then 80-90 parts by weight of hollow glass microspheres are added. The mixture is stirred at 35-50° C. for 24-28 hours to react, filtered, washed with ethyl acetate, and finally vacuum dried at 50-60° C. until constant weight is achieved. The preparation is completed.

[0022] Preferably, the particle size of the hollow glass microspheres in step A is 80-100 μm, and the wall thickness of the hollow glass microspheres is 1-2 μm.

[0023] As a preferred technical solution of the present invention, the defoaming agent is at least one of defoaming agent 901W and defoaming agent 1370.

[0024] As a preferred technical solution of the present invention, the film-forming aid is lauryl alcohol ester.

[0025] A method for preparing a heat-insulating exterior wall coating, comprising the following steps:

[0026] (1) Adding styrene acrylic emulsion, titanium dioxide, defoaming agent, propylene glycol and film-forming aid to deionized water, stirring at a speed of 3000-4000 r / min for 15-20 minutes to obtain solution A;

[0027] (2) Add the composite thermal insulation filler to solution A, stir and mix at a speed of 2000-3000 r / min for 15-20 minutes, and the preparation is completed.

[0028] Beneficial effects of the present invention:

[0029] (1) The present invention creatively modifies and compounds the thermal insulation filler so that the water-based coating formed after mixing it with other components has better thermal insulation performance. On the one hand, the present invention uses TMCS to treat the silica aerogel in the preparation, and a large number of methyl groups are grafted on the surface, which can better maintain its inherent properties. On the other hand, 3-aminopropyltrihydroxysilane is used to modify the hollow glass microspheres, and more hydrophilic groups are grafted on the surface to enhance their hydrophilicity. Finally, polyvinyl alcohol is used as a bridging substance to compound the grafted silica aerogel and hollow glass microspheres to form an inorganic-organic-inorganic filler. In practical applications, not only does the strength of the thermal insulation filler itself increase, it is not easy to break even under high-speed dispersion, and it can also be well dispersed in the water-based coating to form a uniform system.

[0030] (2) The present invention creatively solves the problems existing in the background art by chemically compounding silica aerogel and hollow glass microspheres. With hollow glass microspheres as the main component and silica aerogel as the auxiliary component, the coating is endowed with excellent thermal insulation properties by improving thermal resistance and extending the heat transfer path. Compared with the prior art method of directly compounding by physical blending, the present invention has a better effect. At the same time, the thermal insulation coating prepared by the present invention uses water as the dispersion medium, which reduces the emission of volatile organic pollutants and is very environmentally friendly.

[0031] (3) When the thermal insulation coating prepared by the present invention is applied to the coating of the exterior wall, it not only has excellent thermal insulation and sun protection effects, but also has strong adhesion and is not prone to falling off. DETAILED DESCRIPTION

[0032] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the specific implementation methods, structures, features and effects of the present invention are described in detail below in combination with the embodiments.

[0033] Example 1

[0034] A thermal insulation coating for exterior walls is prepared from 90 parts by weight of styrene acrylic emulsion, 60 parts by weight of deionized water, 25 parts by weight of a composite thermal insulation filler, 10 parts by weight of titanium dioxide, 2 parts by weight of a defoamer, 2 parts by weight of propylene glycol, and 2 parts by weight of a film-forming aid.

[0035] The solid content of the styrene acrylic emulsion is 45%.

[0036] The composite thermal insulation filler is prepared by the following steps:

[0037] Step a: adding tetraethoxysilane and anhydrous ethanol to deionized water, stirring for 5 minutes, and then adjusting the pH to 3 with hydrochloric acid solution to obtain solution a;

[0038] Step b: stirring solution a at room temperature for 24 hours to react, then adjusting the pH to 7 with aqueous ammonia, standing for 10 hours, and filtering to obtain wet gel a;

[0039] Step c: adding anhydrous ethanol to wet gel a until it is completely immersed, then aging at 50°C for 24 hours, filtering to obtain wet gel b, and finally adding a mixed solution of trimethylchlorosilane and n-hexane until it is completely immersed, standing for 48 hours, and filtering to obtain wet gel c;

[0040] Step d: washing the wet gel c with n-hexane five times, and then drying it under vacuum at 50° C. until constant weight is obtained to obtain a hydrophobically modified silica aerogel;

[0041] Step e: adding 10 parts by weight of polyvinyl alcohol and 0.5 parts by weight of p-toluenesulfonic acid to 170 parts by weight of deionized water, stirring at 95° C. until completely dissolved, then adding 70 parts by weight of modified hollow glass microspheres and 25 parts by weight of hydrophobically modified silica aerogel, stirring at 95° C. for 2 hours to obtain solution b;

[0042] Step f: Solution b is naturally cooled to room temperature, filtered, the filtrate is removed, washed with n-hexane, and then vacuum dried at 50° C. until constant weight is reached. The preparation is completed.

[0043] The molar ratio of deionized water, tetraethoxysilane and anhydrous ethanol in step a is 4:1:7.

[0044] The mass fraction of the hydrochloric acid solution in step a is 20%.

[0045] The mass fraction of the ammonia water in step b is 25%.

[0046] The mixed solution of trimethylchlorosilane and n-hexane in step c is prepared according to a volume ratio of trimethylchlorosilane to n-hexane of 1:8.

[0047] The modified hollow glass microspheres in step e are prepared by the following steps:

[0048] Step A: 8 parts by weight of 3-aminopropyltrihydroxysilane and 100 parts by weight of anhydrous ethanol were mixed, and then 80 parts by weight of hollow glass microspheres were added. The mixture was stirred at 35° C. for 24 hours to react, filtered, washed with ethyl acetate, and finally vacuum dried at 50° C. until constant weight was achieved. The preparation was completed.

[0049] The particle size of the hollow glass microspheres in step A is 80 μm, and the wall thickness of the hollow glass microspheres is 1 μm.

[0050] The defoamer is defoamer 901W.

[0051] The film-forming aid is lauryl alcohol ester.

[0052] A method for preparing a heat-insulating exterior wall coating, comprising the following steps:

[0053] (1) Adding styrene acrylic emulsion, titanium dioxide, defoaming agent, propylene glycol and film-forming aid to deionized water, stirring at a speed of 3000 r / min for 15 minutes to obtain solution A;

[0054] (2) Add the composite thermal insulation filler to solution A and stir at a speed of 2000 r / min for 15 minutes to complete the preparation.

[0055] Example 2

[0056] A thermal insulation coating for exterior walls is prepared from 100 parts by weight of styrene acrylic emulsion, 80 parts by weight of deionized water, 30 parts by weight of composite thermal insulation filler, 15 parts by weight of titanium dioxide, 3 parts by weight of a defoamer, 3 parts by weight of propylene glycol, and 3 parts by weight of a film-forming aid.

[0057] The solid content of the styrene acrylic emulsion is 50%.

[0058] The composite thermal insulation filler is prepared by the following steps:

[0059] Step a: adding tetraethoxysilane and anhydrous ethanol to deionized water, stirring for 10 minutes to mix, and then adjusting the pH to 4 with hydrochloric acid solution to obtain solution a;

[0060] Step b: stirring solution a at room temperature for 28 hours to react, then adjusting the pH to 8 with aqueous ammonia, standing for 12 hours, and filtering to obtain wet gel a;

[0061] Step c: adding anhydrous ethanol to wet gel a until it is completely immersed, then aging at 60°C for 26 hours, filtering to obtain wet gel b, and finally adding a mixed solution of trimethylchlorosilane and n-hexane until it is completely immersed, standing for 72 hours, and filtering to obtain wet gel c;

[0062] Step d: washing the wet gel c with n-hexane 8 times, and then drying it under vacuum at 60° C. until constant weight is obtained to obtain a hydrophobically modified silica aerogel;

[0063] Step e: adding 15 parts by weight of polyvinyl alcohol and 1 part by weight of p-toluenesulfonic acid to 180 parts by weight of deionized water, stirring at 95° C. until completely dissolved, then adding 80 parts by weight of modified hollow glass microspheres and 30 parts by weight of hydrophobically modified silica aerogel, and stirring at 100° C. for 3 hours to obtain solution b;

[0064] Step f: Solution b is naturally cooled to room temperature, filtered, the filtrate is removed, washed with n-hexane, and then vacuum dried at 60° C. until constant weight is reached. The preparation is completed.

[0065] The molar ratio of deionized water, tetraethoxysilane and anhydrous ethanol in step a is 5:2:9.

[0066] The mass fraction of the hydrochloric acid solution in step a is 30%.

[0067] The mass fraction of the ammonia water in step b is 30%.

[0068] The mixed solution of trimethylchlorosilane and n-hexane in step c is prepared according to a volume ratio of trimethylchlorosilane to n-hexane of 1.5:10.

[0069] The modified hollow glass microspheres described in step e are prepared by the following steps:

[0070] Step A: 12 parts by weight of 3-aminopropyltrihydroxysilane and 120 parts by weight of anhydrous ethanol were mixed, and then 90 parts by weight of hollow glass microspheres were added. The mixture was stirred at 50° C. for 28 hours to react, filtered, washed with ethyl acetate, and finally vacuum dried at 60° C. until constant weight was achieved. The preparation was completed.

[0071] The particle size of the hollow glass microspheres in step A is 100 μm, and the wall thickness of the hollow glass microspheres is 2 μm.

[0072] The defoamer is defoamer 901W.

[0073] The film-forming aid is lauryl alcohol ester.

[0074] A method for preparing a heat-insulating exterior wall coating, comprising the following steps:

[0075] (1) Adding styrene acrylic emulsion, titanium dioxide, defoaming agent, propylene glycol and film-forming aid to deionized water, stirring at 4000 r / min for 20 min to obtain solution A;

[0076] (2) Add the composite thermal insulation filler to solution A and stir at a speed of 3000 r / min for 20 minutes to complete the preparation.

[0077] Example 3

[0078] A thermal insulation coating for exterior walls is prepared from 95 parts by weight of a styrene-acrylic emulsion, 70 parts by weight of deionized water, 28 parts by weight of a composite thermal insulation filler, 13 parts by weight of titanium dioxide, 2.5 parts by weight of a defoaming agent, 2.5 parts by weight of propylene glycol, and 2.5 parts by weight of a film-forming aid.

[0079] The solid content of the styrene acrylic emulsion is 47%.

[0080] The composite thermal insulation filler is prepared by the following steps:

[0081] Step a: adding tetraethoxysilane and anhydrous ethanol to deionized water, stirring for 8 minutes, and then adjusting the pH to 3.5 with hydrochloric acid solution to obtain solution a;

[0082] Step b: stirring solution a at room temperature for 26 hours to react, then adjusting the pH to 7.5 with aqueous ammonia, standing for 11 hours, and filtering to obtain wet gel a;

[0083] Step c: adding anhydrous ethanol to wet gel a until it is completely immersed, then aging at 55°C for 25 hours, filtering to obtain wet gel b, and finally adding a mixed solution of trimethylchlorosilane and n-hexane until it is completely immersed, standing for 60 hours, and filtering to obtain wet gel c;

[0084] Step d: washing the wet gel c with n-hexane seven times, and then drying it under vacuum at 55° C. until constant weight is obtained to obtain a hydrophobically modified silica aerogel;

[0085] Step e: adding 13 parts by weight of polyvinyl alcohol and 0.8 parts by weight of p-toluenesulfonic acid to 175 parts by weight of deionized water, stirring at 95° C. until completely dissolved, then adding 75 parts by weight of modified hollow glass microspheres and 28 parts by weight of hydrophobically modified silica aerogel, and stirring at 98° C. for 2.5 hours to obtain solution b;

[0086] Step f: Solution b is naturally cooled to room temperature, filtered, the filtrate is removed, washed with n-hexane, and then vacuum dried at 55° C. until constant weight is reached. The preparation is completed.

[0087] The molar ratio of deionized water, tetraethoxysilane and anhydrous ethanol in step a is 4.5:1.5:8.

[0088] The mass fraction of the hydrochloric acid solution in step a is 25%.

[0089] The mass fraction of the ammonia water in step b is 28%.

[0090] The mixed solution of trimethylchlorosilane and n-hexane in step c is prepared according to a volume ratio of trimethylchlorosilane to n-hexane of 1.3:9.

[0091] The modified hollow glass microspheres described in step e are prepared by the following steps:

[0092] Step A: 10 parts by weight of 3-aminopropyltrihydroxysilane and 110 parts by weight of anhydrous ethanol were mixed, and then 85 parts by weight of hollow glass microspheres were added. The mixture was stirred at 40° C. for 26 hours, filtered, washed with ethyl acetate, and finally vacuum dried at 55° C. until constant weight was achieved.

[0093] The particle size of the hollow glass microspheres in step A is 90 μm, and the wall thickness of the hollow glass microspheres is 1.5 μm.

[0094] The defoamer is defoamer 901W.

[0095] The film-forming aid is lauryl alcohol ester.

[0096] A method for preparing a heat-insulating exterior wall coating, comprising the following steps:

[0097] (1) Adding styrene acrylic emulsion, titanium dioxide, defoaming agent, propylene glycol and film-forming aid to deionized water, stirring at a speed of 3500 r / min for 18 minutes to obtain solution A;

[0098] (2) Add the composite thermal insulation filler to solution A and stir at a speed of 2500 r / min for 18 minutes to complete the preparation.

[0099] Comparative Example 1

[0100] A thermal insulation coating for exterior walls is prepared from 90 parts by weight of styrene acrylic emulsion, 60 parts by weight of deionized water, 25 parts by weight of a composite thermal insulation filler, 10 parts by weight of titanium dioxide, 2 parts by weight of a defoamer, 2 parts by weight of propylene glycol, and 2 parts by weight of a film-forming aid.

[0101] The solid content of the styrene acrylic emulsion is 45%.

[0102] The composite thermal insulation filler is prepared by the following steps:

[0103] Step a: adding tetraethoxysilane and anhydrous ethanol to deionized water, stirring for 5 minutes, and then adjusting the pH to 3 with hydrochloric acid solution to obtain solution a;

[0104] Step b: stirring solution a at room temperature for 24 hours to react, then adjusting the pH to 7 with aqueous ammonia, standing for 10 hours, and filtering to obtain wet gel a;

[0105] Step c: adding anhydrous ethanol to the wet gel a until it is completely immersed, then aging at 50° C. for 24 hours, and filtering to obtain the wet gel b;

[0106] Step d: washing the wet gel b with n-hexane five times, and then vacuum drying at 50° C. until constant weight is obtained to obtain a silica aerogel;

[0107] Step e: adding 10 parts by weight of polyvinyl alcohol and 0.5 parts by weight of p-toluenesulfonic acid to 170 parts by weight of deionized water, stirring at 95° C. until completely dissolved, then adding 70 parts by weight of modified hollow glass microspheres and 25 parts by weight of silica aerogel, stirring at 95° C. for 2 hours to obtain solution b;

[0108] Step f: Solution b is naturally cooled to room temperature, filtered, the filtrate is removed, washed with n-hexane, and then vacuum dried at 50° C. until constant weight is reached. The preparation is completed.

[0109] The molar ratio of deionized water, tetraethoxysilane and anhydrous ethanol in step a is 4:1:7.

[0110] The mass fraction of the hydrochloric acid solution in step a is 20%.

[0111] The mass fraction of the ammonia water in step b is 25%.

[0112] The modified hollow glass microspheres in step e are prepared by the following steps:

[0113] Step A: 8 parts by weight of 3-aminopropyltrihydroxysilane and 100 parts by weight of anhydrous ethanol were mixed, and then 80 parts by weight of hollow glass microspheres were added. The mixture was stirred at 35° C. for 24 hours to react, filtered, washed with ethyl acetate, and finally vacuum dried at 50° C. until constant weight was achieved. The preparation was completed.

[0114] The particle size of the hollow glass microspheres in step A is 80 μm, and the wall thickness of the hollow glass microspheres is 1 μm.

[0115] The defoamer is defoamer 901W.

[0116] The film-forming aid is lauryl alcohol ester.

[0117] A method for preparing a heat-insulating exterior wall coating, comprising the following steps:

[0118] (1) Adding styrene acrylic emulsion, titanium dioxide, defoaming agent, propylene glycol and film-forming aid to deionized water, stirring at a speed of 3000 r / min for 15 minutes to obtain solution A;

[0119] (2) Add the composite thermal insulation filler to solution A and stir at a speed of 2000 r / min for 15 minutes to complete the preparation.

[0120] Comparative Example 2

[0121] A thermal insulation coating for exterior walls is prepared from 90 parts by weight of styrene acrylic emulsion, 60 parts by weight of deionized water, 25 parts by weight of a composite thermal insulation filler, 10 parts by weight of titanium dioxide, 2 parts by weight of a defoamer, 2 parts by weight of propylene glycol, and 2 parts by weight of a film-forming aid.

[0122] The solid content of the styrene acrylic emulsion is 45%.

[0123] The composite thermal insulation filler is prepared by the following steps:

[0124] Step a: adding tetraethoxysilane and anhydrous ethanol to deionized water, stirring for 5 minutes, and then adjusting the pH to 3 with hydrochloric acid solution to obtain solution a;

[0125] Step b: stirring solution a at room temperature for 24 hours to react, then adjusting the pH to 7 with aqueous ammonia, standing for 10 hours, and filtering to obtain wet gel a;

[0126] Step c: adding anhydrous ethanol to wet gel a until it is completely immersed, then aging at 50°C for 24 hours, filtering to obtain wet gel b, and finally adding a mixed solution of trimethylchlorosilane and n-hexane until it is completely immersed, standing for 48 hours, and filtering to obtain wet gel c;

[0127] Step d: washing the wet gel c with n-hexane five times, and then drying it under vacuum at 50° C. until constant weight is obtained to obtain a hydrophobically modified silica aerogel;

[0128] Step e: adding 10 parts by weight of polyvinyl alcohol and 0.5 parts by weight of p-toluenesulfonic acid to 170 parts by weight of deionized water, stirring at 95° C. until completely dissolved, then adding 70 parts by weight of hollow glass microspheres and 25 parts by weight of hydrophobically modified silica aerogel, and stirring at 95° C. for 2 hours to obtain solution b;

[0129] Step f: Solution b is naturally cooled to room temperature, filtered, the filtrate is removed, washed with n-hexane, and then vacuum dried at 50° C. until constant weight is reached. The preparation is completed.

[0130] The molar ratio of deionized water, tetraethoxysilane and anhydrous ethanol in step a is 4:1:7.

[0131] The mass fraction of the hydrochloric acid solution in step a is 20%.

[0132] The mass fraction of the ammonia water in step b is 25%.

[0133] The mixed solution of trimethylchlorosilane and n-hexane in step c is prepared according to a volume ratio of trimethylchlorosilane to n-hexane of 1:8.

[0134] In step e, the particle size of the hollow glass microspheres is 80 μm, and the wall thickness of the hollow glass microspheres is 1 μm.

[0135] The defoamer is defoamer 901W.

[0136] The film-forming aid is lauryl alcohol ester.

[0137] A method for preparing a heat-insulating exterior wall coating, comprising the following steps:

[0138] (1) Adding styrene acrylic emulsion, titanium dioxide, defoaming agent, propylene glycol and film-forming aid to deionized water, stirring at a speed of 3000 r / min for 15 minutes to obtain solution A;

[0139] (2) Add the composite thermal insulation filler to solution A and stir at a speed of 2000 r / min for 15 minutes to complete the preparation.

[0140] Comparative Example 3

[0141] A thermal insulation coating for exterior walls is prepared from 90 parts by weight of styrene acrylic emulsion, 60 parts by weight of deionized water, 25 parts by weight of a composite thermal insulation filler, 10 parts by weight of titanium dioxide, 2 parts by weight of a defoamer, 2 parts by weight of propylene glycol, and 2 parts by weight of a film-forming aid.

[0142] The solid content of the styrene acrylic emulsion is 45%.

[0143] The composite thermal insulation filler is prepared by the following steps:

[0144] Step a: adding tetraethoxysilane and anhydrous ethanol to deionized water, stirring for 5 minutes, and then adjusting the pH to 3 with hydrochloric acid solution to obtain solution a;

[0145] Step b: stirring solution a at room temperature for 24 hours to react, then adjusting the pH to 7 with aqueous ammonia, standing for 10 hours, and filtering to obtain wet gel a;

[0146] Step c: adding anhydrous ethanol to wet gel a until it is completely immersed, then aging at 50°C for 24 hours, filtering to obtain wet gel b, and finally adding a mixed solution of trimethylchlorosilane and n-hexane until it is completely immersed, standing for 48 hours, and filtering to obtain wet gel c;

[0147] Step d: washing the wet gel c with n-hexane five times, and then drying it under vacuum at 50° C. until constant weight is obtained to obtain a hydrophobically modified silica aerogel;

[0148] Step e: adding 0.5 parts by weight of p-toluenesulfonic acid to 170 parts by weight of deionized water, stirring at 95° C. until completely dissolved, then adding 70 parts by weight of modified hollow glass microspheres and 25 parts by weight of hydrophobically modified silica aerogel, and stirring at 95° C. for 2 hours to obtain solution b;

[0149] Step f: Solution b is naturally cooled to room temperature, filtered, the filtrate is removed, washed with n-hexane, and then vacuum dried at 50° C. until constant weight is reached. The preparation is completed.

[0150] The molar ratio of deionized water, tetraethoxysilane and anhydrous ethanol in step a is 4:1:7.

[0151] The mass fraction of the hydrochloric acid solution in step a is 20%.

[0152] The mass fraction of the ammonia water in step b is 25%.

[0153] The mixed solution of trimethylchlorosilane and n-hexane in step c is prepared according to a volume ratio of trimethylchlorosilane to n-hexane of 1:8.

[0154] The modified hollow glass microspheres described in step e are prepared by the following steps:

[0155] Step A: 8 parts by weight of 3-aminopropyltrihydroxysilane and 100 parts by weight of anhydrous ethanol were mixed, and then 80 parts by weight of hollow glass microspheres were added. The mixture was stirred at 35° C. for 24 hours to react, filtered, washed with ethyl acetate, and finally vacuum dried at 50° C. until constant weight was achieved. The preparation was completed.

[0156] The particle size of the hollow glass microspheres in step A is 80 μm, and the wall thickness of the hollow glass microspheres is 1 μm.

[0157] The defoamer is defoamer 901W.

[0158] The film-forming aid is lauryl alcohol ester.

[0159] A method for preparing a heat-insulating exterior wall coating, comprising the following steps:

[0160] (1) Adding styrene acrylic emulsion, titanium dioxide, defoaming agent, propylene glycol and film-forming aid to deionized water, stirring at a speed of 3000 r / min for 15 minutes to obtain solution A;

[0161] (2) Add the composite thermal insulation filler to solution A and stir at a speed of 2000 r / min for 15 minutes to complete the preparation.

[0162] Comparative Example 4

[0163] A thermal insulation coating for exterior walls is prepared from 90 parts by weight of styrene acrylic emulsion, 60 parts by weight of deionized water, 25 parts by weight of a composite thermal insulation filler, 10 parts by weight of titanium dioxide, 2 parts by weight of a defoamer, 2 parts by weight of propylene glycol, and 2 parts by weight of a film-forming aid.

[0164] The solid content of the styrene acrylic emulsion is 45%.

[0165] The composite thermal insulation filler is prepared by the following steps:

[0166] Step a: adding tetraethoxysilane and anhydrous ethanol to deionized water, stirring for 5 minutes, and then adjusting the pH to 3 with hydrochloric acid solution to obtain solution a;

[0167] Step b: stirring solution a at room temperature for 24 hours to react, then adjusting the pH to 7 with aqueous ammonia, standing for 10 hours, and filtering to obtain wet gel a;

[0168] Step c: adding anhydrous ethanol to wet gel a until it is completely immersed, then aging at 50°C for 24 hours, filtering to obtain wet gel b, and finally adding a mixed solution of trimethylchlorosilane and n-hexane until it is completely immersed, standing for 48 hours, and filtering to obtain wet gel c;

[0169] Step d: washing the wet gel c with n-hexane five times, and then drying it under vacuum at 50° C. until constant weight is obtained to obtain a hydrophobically modified silica aerogel;

[0170] Step e: 70 parts by weight of the modified hollow glass microspheres and 25 parts by weight of the hydrophobically modified silica aerogel are mixed to complete the preparation.

[0171] The molar ratio of deionized water, tetraethoxysilane and anhydrous ethanol in step a is 4:1:7.

[0172] The mass fraction of the hydrochloric acid solution in step a is 20%.

[0173] The mass fraction of the ammonia water in step b is 25%.

[0174] The mixed solution of trimethylchlorosilane and n-hexane in step c is prepared according to a volume ratio of trimethylchlorosilane to n-hexane of 1:8.

[0175] The modified hollow glass microspheres described in step e are prepared by the following steps:

[0176] Step A: 8 parts by weight of 3-aminopropyltrihydroxysilane and 100 parts by weight of anhydrous ethanol were mixed, and then 80 parts by weight of hollow glass microspheres were added. The mixture was stirred at 35° C. for 24 hours to react, filtered, washed with ethyl acetate, and finally vacuum dried at 50° C. until constant weight was achieved. The preparation was completed.

[0177] The particle size of the hollow glass microspheres in step A is 80 μm, and the wall thickness of the hollow glass microspheres is 1 μm.

[0178] The defoamer is defoamer 901W.

[0179] The film-forming aid is lauryl alcohol ester.

[0180] A method for preparing a heat-insulating exterior wall coating, comprising the following steps:

[0181] (1) Adding styrene acrylic emulsion, titanium dioxide, defoaming agent, propylene glycol and film-forming aid to deionized water, stirring at a speed of 3000 r / min for 15 minutes to obtain solution A;

[0182] (2) Add the composite thermal insulation filler to solution A and stir at a speed of 2000 r / min for 15 minutes to complete the preparation.

[0183] Test Example 1

[0184] Thermal insulation performance test:

[0185] The thermal insulation performance of the thermal insulation exterior wall coatings prepared in Example 1 and Comparative Examples 1-4 was tested according to standard GB / T 25261-2018.

[0186] Table 1. Thermal insulation performance test results

[0187] Thermal conductivity / [W / (m·K)] Example 1 0.021 Comparative Example 1 0.052 Comparative Example 2 0.045 Comparative Example 3 0.031 Comparative Example 4 0.059

[0188] By comparing Example 1, Comparative Examples 1-4 and Test Example 1, it can be seen that:

[0189] The difference between Comparative Example 1 and Example 1 is that the silica aerogel is not hydrophobically modified.

[0190] The difference between Comparative Example 2 and Example 1 is that the hollow glass microspheres are not subjected to hydrophilic modification.

[0191] The difference between Comparative Example 3 and Example 1 is that no polyvinyl alcohol is added for compounding.

[0192] The difference between Comparative Example 4 and Example 1 is that the thermal insulation filler is directly compounded in the form of physical blending.

[0193] From the comparison of Example 1, Comparative Examples 1-4 and Test Example 1, it can be seen that the thermal insulation exterior wall coating prepared by the present invention has excellent thermal insulation performance; Comparative Example 1 does not perform hydrophobic modification on the silica aerogel, and structural collapse is prone to occur when directly applied to water-based paint; Comparative Example 2 does not perform hydrophilic modification on the hollow glass microspheres, resulting in a decrease in dispersibility in water-based paint; Comparative Example 3 does not add polyvinyl alcohol for compounding, and the strength decreases; the physical blending form of Comparative Example 4 not only leads to poor dispersibility, but also average strength.

[0194] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any person skilled in the art can, without departing from the scope of the technical solution of the present invention, make some changes or modifications to equivalent embodiments using the technical contents disclosed above. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A thermal insulation coating for exterior walls, characterized by: The thermal insulation exterior wall coating is prepared from 90-100 parts by weight of styrene acrylic emulsion, 60-80 parts by weight of deionized water, 25-30 parts by weight of composite thermal insulation filler, 10-15 parts by weight of titanium dioxide, 2-3 parts by weight of defoaming agent, 2-3 parts by weight of propylene glycol and 2-3 parts by weight of film-forming aid; The composite thermal insulation filler is prepared by the following steps: Step a: adding tetraethoxysilane and anhydrous ethanol to deionized water, stirring for 5-10 minutes to mix, and then adjusting the pH to 3-4 with hydrochloric acid solution to obtain solution a; Step b: stirring solution a at room temperature for 24-28 hours to react, then adjusting the pH to 7-8 with aqueous ammonia, standing for 10-12 hours, and filtering to obtain wet gel a; Step c: adding anhydrous ethanol to the wet gel a until it is completely immersed, then aging at 50-60° C. for 24-26 hours, filtering to obtain a wet gel b, and finally adding a mixed solution of trimethylchlorosilane and n-hexane until it is completely immersed, standing for 48-72 hours, and filtering to obtain a wet gel c; Step d: washing the wet gel c with n-hexane 5-8 times, and then vacuum drying at 50-60° C. until constant weight is obtained to obtain a hydrophobically modified silica aerogel; Step e: adding 10-15 parts by weight of polyvinyl alcohol and 0.5-1 parts by weight of p-toluenesulfonic acid to 170-180 parts by weight of deionized water, stirring at 95° C. until completely dissolved, then adding 70-80 parts by weight of modified hollow glass microspheres and 25-30 parts by weight of hydrophobically modified silica aerogel, and stirring at 95-100° C. for 2-3 hours to obtain solution b; the modified hollow glass microspheres are obtained by modifying the hollow glass microspheres with 3-aminopropyltrihydroxysilane; Step f: Cool solution b naturally to room temperature, filter, remove the filtrate, wash with n-hexane, and then vacuum dry at 50-60° C. until constant weight is reached. The preparation is completed.

2. The heat-insulating exterior wall coating according to claim 1, characterized in that: The solid content of the styrene acrylic emulsion is 45-50%.

3. The heat-insulating exterior wall coating according to claim 1, characterized in that: The molar ratio of deionized water, tetraethoxysilane and anhydrous ethanol in step a is 4-5:1-2:7-9.

4. The heat-insulating exterior wall coating according to claim 1, characterized in that: The mass fraction of the hydrochloric acid solution in step a is 20-30%.

5. The heat-insulating exterior wall coating according to claim 1, characterized in that: The mass fraction of the ammonia water in step b is 25-30%.

6. The heat-insulating exterior wall coating according to claim 1, characterized in that: The mixed solution of trimethylchlorosilane and n-hexane in step c is prepared according to a volume ratio of trimethylchlorosilane to n-hexane of 1-1.5:8-10.

7. The heat-insulating exterior wall coating according to claim 1, characterized in that: The modified hollow glass microspheres described in step e are prepared by the following steps: Step A: 8-12 parts by weight of 3-aminopropyltrihydroxysilane and 100-120 parts by weight of anhydrous ethanol are mixed, and then 80-90 parts by weight of hollow glass microspheres are added. The mixture is stirred at 35-50° C. for 24-28 hours to react, filtered, washed with ethyl acetate, and finally vacuum dried at 50-60° C. until constant weight is achieved. The preparation is completed.

8. The heat-insulating exterior wall coating according to claim 1, characterized in that: The film-forming aid is lauryl alcohol ester.

9. A method for preparing the thermal insulation exterior wall coating according to any one of claims 1 to 8, characterized in that: The preparation method comprises the following steps: (1) Adding styrene acrylic emulsion, titanium dioxide, defoaming agent, propylene glycol and film-forming aid to deionized water, stirring at a speed of 3000-4000 r / min for 15-20 minutes to obtain solution A; (2) Add the composite thermal insulation filler to solution A, stir and mix at a speed of 2000-3000 r / min for 15-20 minutes, and the preparation is completed.