CN108659711B

CN108659711B - Preparation method of silicon-titanium aerogel adsorption and photocatalysis interior wall coating

Info

Publication number: CN108659711B
Application number: CN201810482895.5A
Authority: CN
Inventors: 郑善
Original assignee: Tianjin Weiyuan Technology Development Co ltd
Current assignee: TIANJIN WEIYUAN TECHNOLOGY DEVELOPMENT Co.,Ltd.
Priority date: 2017-06-12
Filing date: 2017-06-12
Publication date: 2021-01-29
Anticipated expiration: 2037-06-12
Also published as: CN108610988A; CN107189692A; CN107189692B; CN108410366A; CN108410366B; CN108659711A

Abstract

The invention belongs to the technical field of functional coatings, and particularly relates to a preparation method of an environment-friendly indoor adsorption and photocatalysis silicon-titanium aerogel interior wall coating, which comprises water A, a mixed material A-1 and a mixed material A-2 in parts by weight, wherein the water A: the material mixing method comprises the following steps of (1) mixing A-1, mixing A-2= 1-3: 2-6: 1-3, wherein the mixed material A-1 comprises nano titanium oxide composite silicon aerogel photocatalyst powder, aerogel powder A, a wetting agent A-1, a wetting agent A-2 and pigment and filler A, and the mixed material A-2 is a binder; the preparation method comprises the steps of mixing materials in batches, shearing, stirring and emulsifying to obtain a finished product; the interior wall coating has the functions of adsorbing and decomposing indoor pollutants and self-cleaning, and has long service life.

Description

Preparation method of silicon-titanium aerogel adsorption and photocatalysis interior wall coating

The application is a divisional application of a Chinese invention patent with the patent application number of 201710450934.9 (application date: 2017, 06, 12 and the name of the patent: a silicon-titanium aerogel adsorption and photocatalysis interior wall coating and a preparation method thereof).

Technical Field

The invention belongs to the technical field of functional coatings, and particularly relates to a preparation method of an environment-friendly indoor adsorption and photocatalysis silicon-titanium aerogel interior wall coating.

Background

Formaldehyde is a colorless gas with pungent odor, and daily-used decoration materials and new indoor furniture are main sources of formaldehyde pollution. Due to the limitation of technology and materials, a large amount of formaldehyde residues are generally left in a house after decoration, and scientific research shows that the formaldehyde has very long existence time, the incubation period is generally 3-15 years, the formaldehyde cannot be completely eradicated through simple ventilation and adsorption, and the formaldehyde can be completely removed only through complete decomposition, so that secondary pollution is prevented.

The activated carbon and the diatom ooze are traditional products for removing formaldehyde by utilizing the adsorption function. The active carbon removes formaldehyde through the mode of physical adsorption, and after the adsorption capacity of active carbon reached the saturation, just can't continue effectively to get rid of formaldehyde, when air temperature or humidity change, still can release adsorbed formaldehyde. The diatom ooze is a coating directly used for wall decoration, only has the function of adsorbing formaldehyde, does not have the function of degrading formaldehyde, cannot be continuously adsorbed after the adsorption capacity of the diatom ooze is saturated, and cannot continuously and long-term remove the formaldehyde, so that the formaldehyde cannot be fundamentally eliminated.

Nano titanium dioxide (TiO)₂) The nano titanium dioxide is a new photocatalytic material in recent years, and under the condition of illumination, the nano titanium dioxide can degrade formaldehyde into carbon dioxide and water to completely eliminate the formaldehyde, so that the nano titanium dioxide is an excellent photocatalyst. The nano titanium dioxide plays a photocatalysis role and needs to meet the following conditions: 1. illumination; 2. the particle size of the titanium dioxide reaches the nanometer level, so that the surface of the titanium dioxide particles has strong enough oxidation energy; 3. the crystal phase structure of the nano titanium dioxide is more than anatase type. However, monodisperse nano-titanium dioxide is difficult to prepare, and the specific reasons are as follows: the nano titanium dioxide with the crystal phase structure of more than anatase must be sintered at the high temperature of more than 600 ℃ in the manufacturing process, and the nano materials are agglomerated in the high-temperature sintering process, so the production cost is very high; in addition, because the specific surface area of the nano titanium dioxide is large and the surface energy is also large, the prepared nano titanium dioxide is easy to agglomerate in the dispersion process of other materials in a coating system, so that the photocatalytic effect is reduced and even the photocatalytic effect is ineffective.

In order to purify formaldehyde, some products added with nano titanium dioxide appear in the existing coating, but based on the difficult problem that the nano titanium dioxide is easy to agglomerate in the preparation process, the coating products often only have the adsorption function or only have the photocatalysis function or have the double functions of adsorption and photocatalysis, but the technical difficulty in the preparation process is very high, and the production cost is very high; in addition, the nano titanium dioxide of the coating is easy to generate a catalyst poisoning phenomenon in the using process, and the service life of the coating is shortened.

Chinese patent No. 201210573769.3 discloses a composite photocatalyst air purification water-based interior wall coating, which is characterized in that: comprises a photocatalytic filler, a polyurethane emulsion, propylene glycol phenyl ether, a dispersant, a stabilizer, a wetting agent, water, a mildew preventive, a defoaming agent, a leveling agent, a water-soluble polymer, a water,Thickener, nanometer zinc oxide or nanometer tin dioxide. The air purifying paint developed based on photocatalytic principle for inner wall has photocatalytic function, no adsorption capacity, poor photocatalytic effect and single TiO component₂The catalyst is easy to agglomerate with other materials, and is easy to produce catalyst poisoning, and the service life is short.

Chinese patent No. 201110123361.1 discloses a novel anti-formaldehyde odor-removing full-effect water-based interior wall coating, which comprises formaldehyde-removing emulsion, polyurethane modified acrylic resin, bamboo charcoal powder, nano titanium dioxide photocatalyst, calcium carbonate, pigment filler, defoamer, dispersant, anti-settling agent, water and assistant, wherein the coating removes formaldehyde by a method combining physical adsorption and chemical decomposition, but the nano titanium dioxide photocatalyst is easy to agglomerate in the preparation process of the coating, thereby affecting the catalytic performance of the coating, and in addition, the phenomenon of catalyst poisoning is easy to occur, and the service life is short.

Therefore, it is very important to develop a coating product with long-lasting catalytic effect on formaldehyde.

Disclosure of Invention

The invention aims to overcome the technical defects in the prior art, and provides a preparation method of a silicon-titanium aerogel adsorption and photocatalysis interior wall coating for achieving the purpose of long-acting catalysis effect on formaldehyde.

The technical scheme adopted by the invention is as follows:

the silicon-titanium aerogel adsorption and photocatalysis interior wall coating comprises water A, a mixed material A-1 and a mixed material A-2 in parts by weight, wherein the water A: the mixing material A-1 and the mixing material A-2 are 1-3: 2-6: 1-3;

the mixed material A-1 comprises nano titanium oxide composite silicon aerogel photocatalyst powder, aerogel powder A, a wetting agent A-1, a wetting agent A-2 and a pigment filler A, wherein the added weight part of the aerogel powder A is 0.02-0.25 times of the weight part of the nano titanium oxide composite silicon aerogel photocatalyst powder, the added weight part of the wetting agent A-1 is 0.5-3 times of the weight part of the nano titanium oxide composite silicon aerogel photocatalyst powder, the added weight part of the wetting agent A-2 is 0.5-2 times of the weight part of the aerogel powder A, and the added weight part of the pigment filler A is 0.5-3 times of the weight part of the nano titanium oxide composite silicon aerogel photocatalyst powder;

the mixed material A-2 comprises, by weight, 1-12 parts of a leveling agent A, 1-20 parts of a dispersing agent A, 1-10 parts of a preservative A, 1-10 parts of a defoaming agent A, 10-50 parts of a styrene-acrylic emulsion A, 5-40 parts of an elastic emulsion A, 5-40 parts of an organic silicon modified acrylic emulsion A, a film forming aid A and a thickening agent A, pH regulator A, wherein the pH value is 7-8.5; the mixed material A-2 is an adhesive;

the film-forming additive A is added in a weight part which is 0.1-12% of the sum of the weight parts of the styrene-acrylic emulsion A, the elastic emulsion A and the organosilicon modified acrylic emulsion A;

the weight part of the thickener A is 0.5-5% of the sum of the weight parts of the styrene-acrylic emulsion A, the elastic emulsion A and the organosilicon modified acrylic emulsion A;

the weight part of the pH regulator A is 0.5-5% of the sum of the weight parts of the styrene-acrylic emulsion A, the elastic emulsion A and the organosilicon modified acrylic emulsion A.

Preferably, the pigment filler A is one or more of zinc oxide A, barium sulfate A, talcum powder A, diatomite A and heavy calcium powder A, and titanium dioxide A.

Preferably, the titanium dioxide A is anatase.

Preferably, the wetting agent A-1 is one or more of methanol A, ethanol A, propanol A, n-butanol A and pentanol A, and the wetting agent A-2 is one or two of ethylene glycol A or propylene glycol A.

Preferably, the solid contents of the styrene-acrylic emulsion A, the elastic emulsion A and the organic silicon modified acrylic emulsion A are more than or equal to 60 percent, and the viscosity is more than or equal to 1000 cps; the leveling agent A is a polyether siloxane leveling agent, the effective component of the defoaming agent A is hydrophobic silicon dioxide, the film-forming additive A is one or more of trimethylpentanediol A, monoisobutyrate A and alcohol ester 12A, the dispersing agent A is an anionic dispersing agent, and the thickening agent A is one or two of hydroxyethyl cellulose A and hydroxymethyl cellulose A.

Specifically, the preparation method of the aerogel powder A comprises the following steps:

(A) preparation of a mixed solution of a silicon source and a solvent

Putting 3.0-4.0 mol of sodium silicate B into a reaction kettle, adding water B which is 1-3 times of the mass of the sodium silicate B for dilution, stirring the reaction kettle at the speed of 80-200 r/min for 30min, and filtering the solution through a 200-mesh sieve to obtain a sodium silicate solution B;

the aqueous solution of sodium silicate is commonly called water glass, which is composed of alkali metal and silicon dioxide in different proportions and has the chemical formula R₂O·nSiO₂In the formula, R₂O is an alkali metal oxide, n is the ratio of the number of moles of silica to the number of moles of alkali metal oxide, called the number of moles of water glass, most commonly sodium silicate waterglass Na₂O·nSiO₂；

(B) Sol gel

Taking acid A, adding metal salt A and rare earth acid salt A into the acid A, uniformly mixing, and adding into the sodium silicate solution B obtained in the step (A) in a spraying manner; rapidly stirring the materials in the reaction kettle at the speed of 1200-2000 r/min while spraying, controlling the pH value of the sodium silicate solution B to be 1.5-3.0, and controlling the average pore diameter to be 15-30 nanometers to obtain sol, wherein the time of the step is 60-120 min;

preferably, in the step (B), the acid A is sulfuric acid B, hydrochloric acid B, oxalic acid B or nitric acid B, and is adjusted to be 6-15 mol/L by water B;

preferably, in the step (B), the metal salt of a is zirconium or aluminum salt of a acid;

preferably, in the step (B), the rare earth A acid salt is cerium A acid salt, yttrium A acid salt or lanthanum A acid salt;

the metal salt A and the rare earth A acid salt are liable to absorb moisture and cause metering inaccuracy, so that in order to accurately quantify the amounts to be added, the metal salt A and the rare earth A acid salt are added in the above step (B) in a molar ratio of 100: 1-6; in the step (B), the mole ratio of the oxide of the metal salt A to the silicon oxide in the sodium silicate B is 2-5: 100, respectively; for example, the metal salt A is aluminum sulfate B, and the molar ratio of the aluminum oxide B to the silicon oxide in the sodium silicate B is 2-5: 100.

(C) gel

Taking sodium hydroxide B or ammonia water B, adding water B to dilute until the pH value is 10-11.5, and adding the mixture into a reaction kettle in a spraying manner; rapidly stirring the materials in the reaction kettle at the speed of 1200-2000 r/min while spraying, stopping spraying when the pH value of the materials in the reaction kettle is 4.5-5.5, and obtaining gel, wherein the time of the step is 80-180 min;

(D) aging of

Continuously stirring the mixture in the reaction kettle at a speed of 20-50 r/min for 3-10 hours, aging the material in the reaction kettle, and controlling the temperature of the material in the reaction kettle to be 35-50 ℃; in the prior art, the aging is generally carried out in a standing mode, the time is consumed for 3-5 days, and the gel is not stirred, because the aging process is generally considered to be required to be carried out in the prior art, and the structural growth of the aerogel can be facilitated by standing;

(E) solvent replacement

Continuously stirring in the reaction kettle for 60-180 min, and simultaneously adding a displacement solvent B with the same volume as the aged material in the reaction kettle in the step (D) to displace the residual water; in the prior art, the structure of the stirring tank is damaged, the stirring tank cannot be used for stirring during replacement, and standing treatment is adopted, so that the consumed time is long; according to the preparation method provided by the invention, the solvent is stirred for 60-180 min during replacement, the replacement period can be greatly shortened, and the microstructure is not damaged;

preferably, in the step (E), the substitution solvent B is one or a mixture of methanol B, acetone B, n-hexane B, or heptane B.

(F) Surface modification

Continuously stirring in the reaction kettle, and continuously adding the coupling agent B with the same volume as the aged material in the reaction kettle in the step (D); stirring for 60-180 min to obtain a silicon aerogel precursor B coated with a displacement solvent B and a coupling agent B;

the coupling agent B added in the surface modification step (F) replaces water in the aerogel micropores, and the coupling agent B is filled in the gas inlet gel micropores, so that the stability of the micropore structure can be improved, and the average of the pore size is improved; in addition, the hydrophobic and hydrophilic functions of the aerogel can be adjusted by adding different coupling agents B for surface modification.

Preferably, in the step (F), the coupling agent B is one or more of hexamethyldisilazane B, bis (trimethylsilyl) acetamide B, methoxytrimethylsilane B, dimethoxydimethylsilane B, phenyltriethoxysilane B, phenyltrimethoxysilane B, vinyltrimethoxysilane B, methyltriethoxysilane B and methyltrimethoxysilane B;

preferably, the stirring in the step (E) or the step (F) is performed in a reaction kettle;

preferably, the stirring in step (E) or step (F) is performed by providing a fast forward stirring (high-speed shear disk) at the center of the reaction kettle and providing a baffle plate at the periphery of the center of the reaction kettle.

The silica aerogel precursor B is a light porous amorphous inorganic nano material with a controllable structure, has a continuous three-dimensional network structure, has the porosity of more than 80 percent, the average pore diameter of about 20nm, the specific surface area of more than 500 square meters per gram and the density of less than 70kg/m³The thermal conductivity coefficient is less than 0.020W/(m.K) at normal temperature and normal pressure, is lower than the thermal conductivity of 0.022W/(m.K) of static air, and is an inexhaustible solid material with low cost, industrialization and low thermal conductivity;

the existing precursor silicon aerogel precursor is prepared by adopting a supercritical drying process at high temperature and high pressure, the production conditions are harsh, the process is complex, the risk is high, the investment on production devices is large, the preparation efficiency is low, the raw material is mainly high-priced silanol, and the cost is high; the silicon aerogel precursor is prepared at normal temperature and normal pressure, the process is simple and stable, the safety is high, the process is reduced from the traditional 300h to 30h, the investment of a production device with the same energy production is only 1/20 of the traditional method, the price of raw materials is more than 10 times lower than that of the traditional silicon source, and the product cost is only 1/10 of the traditional method.

(G) Preparation of silica aerogel powder B

Putting the silicon aerogel precursor B into a drying kettle, filling nitrogen into the drying kettle to remove oxygen until the oxygen content in the drying kettle is less than 3%, and then performing microwave vacuum drying on the material in the drying kettle; drying under the negative pressure of 0.08-0.12 mpa in a drying kettle at the temperature of 80-135 ℃ to obtain solid powdery silicon aerogel powder B, wherein the silicon aerogel powder B is the aerogel powder A adopted in the mixed material A; the silica aerogel precursor B is coated with a replacement solvent B and a coupling agent B, belongs to hydroxide and is changed into solid powdery oxide after microwave drying.

Preferably, in the step (G), the microwave vacuum drying time is 50-80 minutes, and the microwave frequency is 2450MHz +/-10 MHz.

Preferably, the water A and the water B are deionized water; further reducing the production cost.

Specifically, the preparation method of the nano titanium oxide composite silica aerogel photocatalyst powder is prepared according to the method described in ZL201410311741.1 and comprises the following steps:

the preparation method comprises the following steps of (I) passing silicon aerogel particles C through a 300-mesh sieve, and soaking in 20-DEG ammonia water C for 30-36 hours to obtain a material A; mixing rare earth nitrate C in a ratio of 1: dissolving the mixture in deionized water C according to the weight ratio of 1, and filtering to obtain a material B;

(II) because the calibration methods and standards of titanium sulfate C in purchasing are different, in order to more accurately add the amount of titanium sulfate C, the amount of titanium sulfate C converted into titanium oxide C is taken as a calibration means; mixing the required titanium sulfate C with deionized water C with the weight ratio of 95% to prepare a solution, wherein the weight ratio of the titanium sulfate C converted into titanium oxide C is 5%; continuously stirring the solution, heating to 75-90 ℃, keeping constant temperature, controlling the stirring speed at 500-800 r/min, starting ultrasonic vibration, and adding the material A prepared in the step (I) at a constant speed within 60-90 min, wherein the amount of the added material A is determined by the weight of the silica aerogel C, and the weight of the silica aerogel C is 0.36-0.5 time of the weight of the titanium sulfate C converted into the titanium oxide C;

(III) continuously adding a proper amount of ammonia water C to adjust the pH value to 8.0-9.5, then continuously stirring at a stirring speed of 30-80 r/min, and starting ultrasonic vibration while stirring; reacting for 60-90 min to obtain slurry C;

(IV) filtering and washing the slurry C, controlling the pH value of the slurry C to be 7-8, and simultaneously enabling the solid content of the filtered and washed slurry C to be more than 40%; then, adding 2 times of deionized water C, and simultaneously adding a material B (the rare earth nitrate C is easy to absorb moisture, which can cause inaccurate measurement, so that the adding amount of the rare earth nitrate C is accurately quantified, the rare earth nitrate C is calculated by rare earth oxide), wherein the weight of the rare earth nitrate C in the material B is 3-7% of the weight of the titanium oxide C, the stirring speed is controlled at 500-800 r/min, when the temperature is raised to 75-90 ℃ by stirring, dropwise adding ammonia water C to adjust the pH value to 7-7.5, adding hydrogen peroxide C, the adding amount of the hydrogen peroxide C is 10% of the weight of the rare earth nitrate C in the material B, and stirring and reacting for 30 minutes; after washing and filtering, collecting and obtaining slurry D when the solid content of the material is more than 40%;

at the moment, the rare earth nitrate C reacts with the ammonia water C to be converted into a rare earth hydroxide C, and the titanium sulfate C reacts with the ammonia water C to generate titanium hydroxide C; the rare earth hydroxide C is coated on the surface of the titanium hydroxide C and is filled on the specific surface of the silica aerogel C together, and the rare earth hydroxide C and the titanium hydroxide C are filled in the microporous structure of the silica aerogel C; the anions and cations of the rare earth hydroxide C and the titanium hydroxide C are tightly combined, and after spray drying and high-temperature sintering, the rare earth hydroxide C and the titanium hydroxide C are converted into a nano titanium oxide/rare earth oxide solid solution C (the volume of the nano titanium oxide/rare earth oxide solid solution C is reduced to 0.2-0.4 times of the original volume), so that the microporous structure of the silicon aerogel C exists at any time.

(V) spray drying the slurry D, and then feeding the dried slurry D into a tubular oscillation sintering furnace, wherein the heating temperature in the tubular oscillation sintering furnace is 450-600 ℃, so that the titanium hydroxide C and the rare earth hydroxide C coated on the surface of the silicon aerogel C are converted into nano-grade anatase titanium oxide C and rare earth oxide C, and finally the silicon aerogel photocatalyst compounded by the nano titanium oxide and the rare earth oxide solid solution C is obtained, namely the nano titanium oxide composite silicon aerogel photocatalyst powder adopted in the mixed material A.

The prepared silica aerogel photocatalyst compounded by the nano titanium oxide and the lanthanum solid solution C has higher specific surface area and stronger adsorption capacity, so that the catalyst performance is higher.

Preferably, the rare earth nitrate C in the step (I) is lanthanum nitrate C, cerium nitrate C or neodymium nitrate C.

Preferably, the frequency of the ultrasonic vibration in the step (II) or the step (III) is 20 to 35KHz, and the power density is 0.3 to 0.8W/cm². The ultrasonic vibration is adopted, so that the mixing during stirring is more uniform, the formation of nano-scale particles is promoted without agglomeration, and the silicon aerogel C can be uniformly coated by the coating material.

Preferably, the spray drying used in the step (V) has an inlet temperature of 200-300 ℃ and an outlet temperature of 100-120 ℃.

Preferably, the inclination angle of the tubular oscillation sintering furnace in the step (V) is 5-8 degrees, and the vibration frequency is 300-380 times/min.

A preparation method of a silicon-titanium aerogel adsorption and photocatalysis interior wall coating comprises the following steps:

(1) grinding aerogel powder A and a wetting agent A-2 with the weight part of 0.5-2 times of that of the aerogel powder A in a sand mill with the rotating speed of 800-2500 r/min for 20-80 min, and then sieving with a 200-1000 mesh sieve to obtain the particle size (the particle size is D)₅₀Expressed) a mixture of 500nm to 2000nm aerogel powder A and a wetting agent A-2;

particle diameter D₅₀The contact angle of 500-2000 nm aerogel powder A is larger than 140 degrees, and the aerogel powder A is a super-hydrophobic material, so that the surface of the coating is not polluted by dust and moisture, and the self-cleaning function is realized;

the wetting agent A-2 is added in the grinding process of the aerogel powder A, the purpose is to prevent the aerogel particles from being ground, the ground aerogel powder A has uniform granularity and good grinding effect; in addition, in the grinding process, the wetting agent A-2 is used for occupying the porous structure of the three-dimensional space in the aerogel powder A, so that a binder or other materials are prevented from entering the three-dimensional space to block the porous structure in the preparation process of the coating, the wetting agent A-2 naturally volatilizes after the coating is sprayed on a wall, the three-dimensional space structure in the aerogel powder A is still maintained, and the self-cleaning function of the aerogel powder A is ensured to be exerted;

(2) adding the nano titanium oxide composite silicon aerogel photocatalyst powder and the wetting agent A-1 into a kneading machine, uniformly stirring at the stirring speed of 30-250 revolutions per minute for 20-50 minutes, and then adding the mixture of the aerogel powder A with the particle size of 500-2000 nm and the wetting agent A-2 obtained in the step (1) into the kneading machine, uniformly stirring at the stirring speed of 30-250 revolutions per minute for 20-50 minutes; the added weight part of the aerogel powder A is 0.02-0.25 time of that of the nano titanium oxide composite silicon aerogel photocatalyst powder, and the added weight part of the wetting agent A-1 is 0.5-3 times of that of the nano titanium oxide composite silicon aerogel photocatalyst powder, calculated on the basis of the aerogel powder A before grinding and sieving;

the three-dimensional space structure in the nano titanium oxide composite silicon aerogel photocatalyst powder plays an important role in the adsorption and photocatalytic activity of the nano titanium oxide composite silicon aerogel photocatalyst powder, and in the preparation process of the coating, after a binder or other materials enter the three-dimensional space blocking porous structure, the adsorption and photocatalytic activity of the nano titanium oxide composite silicon aerogel photocatalyst powder is reduced or lost; the wetting agent A-1 has the functions of wetting the nano titanium oxide composite silicon aerogel photocatalyst powder, occupying a porous structure of a three-dimensional space in the nano titanium oxide composite silicon aerogel photocatalyst powder, preventing a binder or other materials from entering the three-dimensional space to block the porous structure in the preparation process of the coating, naturally volatilizing the wetting agent A-1 after the coating is sprayed on a wall, and still keeping the three-dimensional space structure in the nano titanium oxide composite silicon aerogel photocatalyst powder to exert adsorption and photocatalytic activity;

(3) adding a pigment filler A and water A into a kneading machine for kneading uniformly, wherein the kneading speed is 100-500 r/min, the kneading time is 10-50 min, the weight part of the pigment filler A is 0.5-3 times of the weight part of the nano titanium oxide composite silicon aerogel photocatalyst powder, and the water A: (aerogel powder A + nano titanium oxide composite silicon aerogel photocatalyst powder + wetting agent A-1+ wetting agent A-2+ pigment filler A) ═ 1-3: 2-6;

(4) 1-12 parts by weight of a leveling agent A, 1-20 parts by weight of a dispersing agent A, 1-10 parts by weight of a preservative A, 1-10 parts by weight of a defoaming agent A, 10-50 parts by weight of a styrene-acrylic emulsion A, 5-40 parts by weight of an elastic emulsion A, 5-40 parts by weight of an organic silicon modified acrylic emulsion A, a film-forming aid A and a thickening agent A, pH regulator A are mixed and stirred uniformly to obtain a mixed material A-2, wherein the stirring speed is 150-850 r/min, the stirring time is 10-50 min, and the pH value of the mixed material A-2 is 7-8.5; according to the weight ratio, the water A: the mixed material A-2 is 1-3: 1-3; the film-forming assistant A is added in a weight part of 0.1-12% of the sum of the weight parts of the styrene-acrylic emulsion A, the elastic emulsion A and the organosilicon modified acrylic emulsion A, the thickener A is added in a weight part of 0.5-5% of the sum of the weight parts of the styrene-acrylic emulsion A, the elastic emulsion A and the organosilicon modified acrylic emulsion A, and the pH regulator A is added in a weight part of 0.5-5% of the sum of the weight parts of the styrene-acrylic emulsion A, the elastic emulsion A and the organosilicon modified acrylic emulsion A;

(5) uniformly stirring the mixture obtained in the step (2), the step (3) and the step (4) in a shearing stirrer at the stirring speed of 50-650 r/min for 25-55 min;

(6) homogenizing the materials by the mixture obtained in the step (5) through an emulsification pump, wherein the rotating speed of the emulsification pump is 500-2500 r/min, and the time for pump-passing is 10-20 min; and (3) sieving the emulsified mixture with a 200-mesh and 300-mesh sieve to obtain the silicon-titanium aerogel adsorption and photocatalysis inner wall coating.

Preferably, in the step (4), the thickening agent A is diluted by 1-5 times of water D before use and stands for 5-24 hours; in the traditional paint preparation process, the cellulose thickener A is directly added into the paint without dilution, and because the cellulose thickener A is a polysaccharide substance, the paint is easy to have the phenomenon of caking due to excessive local viscosity, thereby affecting the performance of the paint; the thickening agent A is diluted by water and is used after being placed for a period of time, so that the phenomenon that the paint is caked due to overlarge local viscosity is avoided, the paint components are uniform, and the performance is very stable.

Working principle of the invention

The silicon aerogel with the nano structure can be used as a novel gas filter, and is different from other materials in that the material has uniform pore size distribution, high porosity and especially large specific surface area, thereby being a high-efficiency gas filter material; according to the invention, the porous characteristic of the aerogel is firstly utilized to adsorb and capture formaldehyde, then the adsorbed and captured formaldehyde is decomposed into carbon dioxide and water by utilizing the photocatalysis of the nano titanium dioxide, and the formaldehyde is fundamentally eliminated by photolysis, so that the formaldehyde is adsorbed and decomposed at the same time, and the effect of removing the formaldehyde for a long time is successfully achieved.

The invention has the beneficial effects that:

1. according to the invention, the nano titanium oxide composite silicon aerogel photocatalyst powder is added into the raw materials for preparing the coating, and the processes of ultrasonic vibration, spray drying, tubular oscillation high-temperature sintering and the like are added into the preparation process of the photocatalyst powder, so that the technical problem that nano titanium oxide easily and spontaneously forms aggregates is solved, and the photocatalyst powder has good photocatalytic performance and can adsorb and catalytically decompose formaldehyde in a long-acting and strong-acting manner;

2. besides formaldehyde, the coating has a long-acting removal effect on other indoor volatile organic compounds (VOC for short), bacteria, viruses and PM 2.5;

3. the aerogel powder A is ground to the particle size of 500-2000 nm, so that the coating has a self-cleaning function, an adsorption and photocatalytic material is protected, only pollutants such as formaldehyde and the like can be adsorbed and degraded by the photocatalyst, the photocatalyst poisoning is prevented, the service life of the photocatalyst is long, and the coating is effective for a long time;

4. the nano titanium oxide composite silicon aerogel photocatalyst powder is nano titanium dioxide and silicon aerogel (nano TiO)₂/Si aerogel), when the coating is used, the silicon aerogel is utilized to adsorb pollutants such as formaldehyde and the like, and the nano TiO is used₂Pollutants such as formaldehyde and the like are photolyzed, and are adsorbed and decomposed simultaneously, so that the long-acting decomposition effect is achieved, the problem of functional failure after adsorption saturation of the adsorption material is solved by adopting a mode of adsorbing and decomposing simultaneously, and the adsorbed pollutants can not be released again;

5. nano titanium oxide composite siliconThe aerogel photocatalyst powder adopts nano TiO₂The composite form of the/Si aerogel has the characteristics of strong effectiveness and long effectiveness, taking formaldehyde removal as an example: firstly, the removal rate of formaldehyde is more than or equal to 95% within 48 hours under a fluorescent lamp; secondly, the long-acting aerogel is responsible for adsorbing formaldehyde and TiO₂The device is responsible for photocatalytic decomposition, formaldehyde is decomposed into water and carbon dioxide, namely, the water and the carbon dioxide are adsorbed and decomposed at the same time, and then the formaldehyde is adsorbed and decomposed again, so that the formaldehyde is continuously removed, the formaldehyde can be adsorbed even in the environment without illumination, and the adsorbed formaldehyde is decomposed again in the presence of illumination;

6. the invention uses nano TiO₂The silicon aerogel is loaded on the surface of the silicon aerogel and has the following two functions:

(1) from the material preparation perspective, make nanometer TiO₂The particles are uniformly dispersed on the surface of the aerogel particles, and the nanometer TiO is used as the blocking effect of the aerogel carrier₂The particles are difficult to attract and agglomerate; in addition, the nanometer TiO is made of amorphous silicon dioxide, ferric oxide, aluminum oxide and other components contained in the aerogel carrier₂The forbidden band width is reduced, the utilization rate of visible light is improved, and the photocatalytic performance of the material under the visible light is obviously improved;

(2) from the aspect of application performance, the nano titanium dioxide is loaded on the silicon aerogel, so that the silicon aerogel not only has the function of adsorbing and capturing formaldehyde molecules dissociating in the air, but also depends on uniformly loading nano TiO fixed on the surface or the wall of the nano hole of the aerogel₂The photocatalysis of the aerogel can decompose formaldehyde adsorbed and captured in the nano holes of the aerogel under the illumination condition; not only solves the problem that the aerogel does not have the photocatalytic degradation function, but also overcomes the defect that monodisperse pure nano titanium dioxide has the adsorption and capture functions; the functions of adsorbing and capturing pollutants such as formaldehyde and the like and the functions of degrading the pollutants such as formaldehyde and the like through photocatalysis are integrated; although, the adsorption material such as aerogel and pure nano TiO are used together₂The combination of the two functions can be realized, however, because of the nanometer TiO₂The dosage of the nano TiO is very small, the nano TiO is difficult to be uniformly dispersed in the adsorption material₂The particles may be a relatively long distance from the adsorbate aerogel particles, asPollutants such as formaldehyde and the like adsorbed in the aerogel particles are difficult to degrade by using the distance limitation; the material is prepared from nano TiO₂The particles are on the surface or the hole wall of the aerogel particles and can act on pollutants such as formaldehyde and the like adsorbed and captured in a short distance, so that the photocatalytic degradation efficiency is high, and the dosage is small;

7. according to the invention, the titanium dioxide is anatase, the crystal grain of the titanium dioxide is 10-20 nm, the titanium dioxide is nano-scale titanium dioxide, the titanium dioxide can be uniformly loaded and fixed on the surface of aerogel particles, the agglomeration phenomenon cannot be generated, the photocatalysis effect is good, and the effect of adsorbing harmful gas is 20-50 times higher than that of similar products, such as activated carbon, diatom ooze and the like;

8. sunlight and lamplight can be used as light sources for photolysis, and the application range is wide;

9. the product is a white liquid coating, and the viscosity of the product is 800-1500 cps;

10. the product of the invention is water-based paint, does not contain benzene, ether, formaldehyde and other volatile organic solvents, is pollution-free, and accords with the modern environmental protection concept;

11. the film-forming assistant A and the flatting agent A in the paint have the traditional functions of being applied in the paint, and also have the function of adjusting the viscosity of the paint;

12. the working principle of the preparation of the silica aerogel powder B is as follows: in the preparation method of the silicon aerogel precursor B, the metal salt A and the rare earth A acid salt are added in the gelling process, so that the effects of toughening and improving the heat resistance of the silicon aerogel can be achieved; the aging and solvent replacement steps are carried out under the stirring state, so that the reaction efficiency is greatly improved, the process time is shortened, and the method is suitable for industrialization; the process for preparing the solid powdery silicon aerogel by using the silicon aerogel precursor B is carried out by adopting a negative pressure microwave drying method, and microwaves can directly penetrate into a microporous structure of the silicon aerogel, so that a heat conduction mode from inside to outside is realized; the microwave can generate microcosmic vibration on the materials in the microporous structure, thereby effectively avoiding the occurrence of agglomeration; under the negative pressure state, the boiling point, the evaporation point or the gasification point of the solvent in the micropores can be reduced;

13. compared with the prior art, the preparation method of the silica aerogel powder B has the following advantages:

(1) in recent years, some related reports and patent documents about preparation of silica aerogel at normal temperature and normal pressure exist in the prior art, but most of the reports and patent documents stay in a laboratory preparation stage, the process is long, and the process implementation range is too narrow, so that large-scale industrial production and application are difficult to realize; the invention provides a preparation method under normal temperature and normal pressure, which changes the relative static process in the prior art, applies stirring in the key process, accelerates the realization of the hydrolysis, polycondensation and modification of aerogel, realizes the process of synthesizing aerogel precursor within 30 hours, provides a method for industrially preparing rare earth toughening silicon aerogel in batches, and provides the premise for the mass production and use of aerogel;

(2) one of the reasons for hindering the development of the aerogel in the prior art is that the aerogel has a net-shaped structure, but the structure has thin and fragile edges, low compressive strength and easy collapse under pressure, so that the performance is unstable; according to the invention, rare earth A acid salt and metal salt A are added, so that the toughness of the material is improved, and the strength of the silica aerogel is improved;

(3) the silica aerogel prepared by the prior art has low use temperature, is generally stable when used below 500 ℃, and can cause the internal structure change of the silica aerogel above 500 ℃ to reduce the heat conductivity coefficient; according to the invention, rare earth A acid salt and metal salt A are added, so that the temperature resistance of the material is improved, and the heat resistance temperature of the silica aerogel is increased;

(4) in the prior art, the commonly adopted methods such as high-temperature sintering, drying and the like in the process of preparing the solid-state silicon aerogel can cause structural collapse or sintering agglomeration in the material sintering process, reduce the specific surface area of the material and greatly influence the heat conductivity coefficient of the material; according to the invention, the silicon aerogel precursor B is subjected to microwave vacuum drying, microwaves can directly penetrate into the microporous structure of the aerogel, and a heat conduction mode from inside to outside is realized; under the negative pressure state, the boiling point, the evaporation point or the gasification point of the solvent in the micropores can be reduced; the microwave can generate micro vibration on the materials in the microporous structure, thereby effectively avoiding the phenomena of structural collapse or sintering agglomeration of the materials caused by high-temperature sintering, drying and other methods, and effectively improving the specific surface area and the heat conductivity coefficient of the materials;

(5) and nitrogen is filled for protection during microwave vacuum drying, and the negative pressure low temperature is used for safely recycling the replacement solvent or the coupling agent so as to reduce the manufacturing cost. Nitrogen is filled for protection during microwave vacuum drying, and the microwave vacuum drying is carried out under the state of negative pressure and low temperature; the microwave vacuum drying gasifies the replacement solvent or the coupling agent in the microporous structure in a negative pressure state, liquefies the replacement solvent or the coupling agent in a low-temperature state, and can realize safe recycling so as to reduce the process cost.

Detailed Description

Mono, nano TiO₂The mechanism of degrading and removing indoor pollutants (comprising VOC, bacteria, viruses and PM2.5) by the aid of the/Si aerogel composite material is illustrated by taking formaldehyde as an example:

formaldehyde in nano TiO₂The surface degradation of the/Si aerogel composite material is divided into two processes: (1) the adsorption process of formaldehyde molecules on the surface of the composite material; (2) formaldehyde molecules adsorbed on the surface of the composite material are irradiated by the photoactive substance TiO₂And (3) degrading.

When the energy exceeds TiO₂Photon irradiation of forbidden band width on nano TiO₂At the surface of the/Si aerogel composite material, is in TiO₂Electrons in the valence band are excited to the conduction band, so that high-activity free-moving photogenerated electrons and holes are generated in the valence band and the conduction band respectively; due to TiO loaded on the surface of the composite material₂Is a nano-scale particle, so electrons and holes generated by light excitation can be quickly transferred from the inside of the body to the surface, and the holes are strong oxidants and can be adsorbed on TiO₂The surface hydroxyl and water are oxidized into OH; the conduction band electrons are strong reducing agent and are adsorbed on TiO₂Capture of dissolved oxygen at the surface to form O₂ ^－(ii) a Moiety. O₂ ^－Can generate OH continuously through chain reaction; formed OH and O₂ ^－Has strong oxidizing property, and is documented in the literature as TiO₂The OH free radical generated by the photocatalytic reaction has the reaction energy of 402.8MJ/mol, which is higher than various chemical bond energies in organic compounds, such as: c-OH and O formed from C (83), C-H (99), C-N (73), C-O (80), N-H (93), H-O (111), etc₂ ^－Can attack the C-H bond of formaldehyde, generate new free radical with active H atom thereof, excite chain reaction, and finally decompose formaldehyde into harmless substances.

Nano TiO 2₂When the/Si aerogel composite material photocatalytically degrades formaldehyde gas, the activity of OH and O₂ ^－The formaldehyde and the carbon dioxide are jointly oxidized, the formaldehyde is firstly oxidized into the formic acid and finally decomposed into the water and the carbon dioxide, and the decomposition mechanism is as follows:

HCHO+·OH→·CHO+H₂O

·CHO-+·OH→HCOOH

the invention is further illustrated by the following examples:

examples 1 to 8

1. The formula of the silicon-titanium aerogel adsorption and photocatalysis interior wall coating comprises water A, a mixed material A-1 and a mixed material A-2, wherein the water A: the mixing material A-1 and the mixing material A-2 are 1-3: 2-6: 1-3, the components in the formula of examples 1-8 are shown in Table 1;

TABLE 1 component ratios of adsorption of TiSi aerogel to photocatalytic interior wall coating in examples 1-8

The mixed material A-1 comprises nano titanium oxide composite silicon aerogel photocatalyst powder, aerogel powder A, a wetting agent A-1, a wetting agent A-2 and a pigment and filler A, wherein the added weight part of the aerogel powder A is 0.02-0.25 times of the weight part of the nano titanium oxide composite silicon aerogel photocatalyst powder, the added weight part of the wetting agent A-1 is 0.5-3 times of the weight part of the nano titanium oxide composite silicon aerogel photocatalyst powder, the added weight part of the wetting agent A-2 is 0.5-2 times of the weight part of the aerogel powder A, the added weight part of the pigment and filler A is 0.5-3 times of the weight part of the nano titanium oxide composite silicon aerogel photocatalyst powder, and the components of the mixed material A-1 in the examples 1-8 are detailed in a table 2;

TABLE 2 component proportion of blends A-1 of examples 1-8

The mixed material A-2 comprises, by weight, 1-12 parts of a leveling agent A, 1-20 parts of a dispersing agent A, 1-10 parts of a preservative A, 1-10 parts of a defoaming agent A, 10-50 parts of a styrene-acrylic emulsion A, 5-40 parts of an elastic emulsion A, 5-40 parts of an organic silicon modified acrylic emulsion A, a film forming aid A and a thickening agent A, pH regulator A, wherein the pH value is 7-8.5;

wherein the added weight part of the film-forming additive A is 0.1-12% of the sum of the weight parts of the styrene-acrylic emulsion A, the elastic emulsion A and the organosilicon modified acrylic emulsion A; the weight part of the thickener A is 0.5-5% of the sum of the weight parts of the styrene-acrylic emulsion A, the elastic emulsion A and the organosilicon modified acrylic emulsion A; the added weight part of the pH regulator A is 0.5-5% of the sum of the weight parts of the styrene-acrylic emulsion A, the elastic emulsion A and the organosilicon modified acrylic emulsion A, and the components of the mixture A-2 in the examples 1-8 are detailed in Table 3;

TABLE 3 component ratios for blends A-2 of examples 1-8

The pigment filler A is one or more of zinc oxide A, barium sulfate A, talcum powder A, diatomite A and coarse whiting powder A, and titanium dioxide A, the titanium dioxide A is anatase, and the specific components and the using amounts of the components of the pigment filler A in the embodiments 1-8 are shown in Table 4;

TABLE 4 detailed tables of specific compositions and amounts of pigment and filler A in examples 1-8

The solid contents of the styrene-acrylic emulsion A, the elastic emulsion A and the organic silicon modified acrylic emulsion A are more than or equal to 60 percent, the viscosity is more than or equal to 1000cps, and the concrete details of the styrene-acrylic emulsion A, the elastic emulsion A and the organic silicon modified acrylic emulsion A in the examples 1-8 are shown in a table 5;

TABLE 5 styrene-acrylic emulsion A, elastic emulsion A, Silicone modified acrylic emulsion A in examples 1-8

The wetting agent A-1 is one or more of methanol A, ethanol A, propanol A, n-butanol A and pentanol A, the wetting agent A-2 is one or two of ethylene glycol A or propylene glycol A, and the specific components of the wetting agent A-1 and the wetting agent A-2 in the embodiments 1-8 are shown in Table 6;

TABLE 6 detailed ingredient lists of wetting agent A-1 and wetting agent A-2 in examples 1 to 8

The water A is deionized water;

the leveling agent A is a polyether siloxane leveling agent, and the effective component of the defoaming agent A is hydrophobic silicon dioxide;

the film forming aid A is one or more of trimethylpentanediol A, monoisobutyrate A and alcohol ester 12A, the dispersant A is an anionic dispersant, the thickener A is one or two of hydroxyethyl cellulose A and hydroxymethyl cellulose A, and the specific components of the film forming aid A and the thickener A in examples 1-8 are shown in Table 7 in detail.

TABLE 7 detailed ingredient lists of film-forming assistant A and thickener A in examples 1 to 8

2. The preparation method of the silicon-titanium aerogel adsorption and photocatalysis interior wall coating comprises the following steps:

(1) weighing the components according to the dosage in the formula;

(2) grinding the aerogel powder A and the wetting agent A-2 in a sand mill at the rotating speed of 800-2500 r/min for 20-80 min, and then sieving with a 200-1000-mesh sieve to obtain a mixture of the aerogel powder A and the wetting agent A-2 with the particle size of 500-2000 nm;

(3) adding the nano titanium oxide composite silicon aerogel photocatalyst powder and the wetting agent A-1 into a kneading machine, uniformly stirring at a primary stirring speed of 30-250 r/min for 20-50 min, and then adding the mixture of the aerogel powder A with the particle size of 500-2000 nm and the wetting agent A-2 obtained in the step (2) into the kneading machine, uniformly stirring at a secondary stirring speed of 30-250 r/min for 20-50 min;

(4) adding the pigment filler A and the water A into a kneading machine for uniformly kneading, wherein the kneading speed is 100-500 r/min, and the kneading time is 10-50 min;

(5) diluting the thickening agent A by using 1-5 times of deionized water D by weight and standing for 5-24 hours; mixing and uniformly stirring a leveling agent A, a dispersing agent A, a preservative A, a defoaming agent A, a styrene-acrylic emulsion A, an elastic emulsion A, an organic silicon modified acrylic emulsion A, a film-forming aid A and a thickening agent A, pH regulator A diluted by deionized water and standing to obtain a mixed material A-2, wherein the pH value of the mixed material A-2 is 7-8.5, and the specific pH value is shown in the component proportion specification of the mixed material A-2 in the embodiment 1-8 of Table 3; the stirring speed is 150-850 r/min, and the stirring time is 10-50 min;

(6) uniformly stirring the mixture obtained in the step (3), the step (4) and the step (5) in a shearing stirrer at the stirring speed of 50-650 r/min for 25-55 min;

(7) homogenizing the materials by the mixture obtained in the step (6) through an emulsification pump, wherein the rotating speed of the emulsification pump is 500-2500 r/min, and the time of pump passing is 10-20 min; sieving the emulsified mixture through a 200-300-mesh sieve to obtain the silicon-titanium aerogel adsorption and photocatalysis inner wall coating; the variable parameters in steps (2) to (7) in examples 1 to 8 are shown in Table 8.

TABLE 8 detailed tables of variable parameters in steps (2) - (7) of examples 1-8

3. Particle size D adopted in silicon-titanium aerogel adsorption and photocatalysis interior wall coating₅₀Is aerogel powder A with the particle size of 500 nm-2000 nm, and comprises the following specific preparation steps:

(A) preparation of a mixed solution of a silicon source and a solvent

Filling water glass B with the mole number of 3.0-4.0 into a reaction kettle, adding deionized water B with the mass of 1-3 times that of the water glass B for dilution, stirring the reaction kettle at the speed of 80-200 rpm for 30 minutes, and filtering the mixture through a 200-mesh sieve to obtain a water glass solution B;

(B) sol gel

Taking acid A, adding metal salt A and rare earth acid salt A into the acid A, uniformly mixing, and adding into the water glass solution B obtained in the step (A) in a spraying manner; rapidly stirring the materials in the reaction kettle at 1200-2000 rpm while spraying, controlling the pH value to 1.5-3.0, stopping spraying, and controlling the spraying time to be 60-120 minutes to obtain sol;

the acid A is sulfuric acid B, hydrochloric acid B, oxalic acid B or nitric acid B, and the concentration of the acid A is adjusted to be 6-15 mol/L by deionized water B;

the A metal salt is A acid zirconium salt or A acid aluminum salt, and the rare earth A acid salt is A acid cerium salt, A acid yttrium salt or A acid lanthanum salt;

the molar ratio of the metal salt A to the rare earth A acid salt is 100: 1-6;

the molar ratio of the oxide of the metal salt A to the silicon oxide in the water glass solution B is 2-5: 100, respectively;

(C) gel

Taking sodium hydroxide B or ammonia water B, adding deionized water B to dilute until the pH value is 10-11.5, and adding the sodium hydroxide B or ammonia water B into the sol obtained in the reaction kettle in the step (B) in a spraying manner; rapidly stirring the materials in the reaction kettle at 1200-2000 rpm while spraying, and when the pH value of the materials in the reaction kettle is 4.5-5.5, spraying for 80-180 minutes to obtain gel;

(D) aging of

Continuously stirring the mixture in the reaction kettle at a speed of 20-50 rpm for 3-10 hours, aging the material in the reaction kettle, and controlling the temperature of the material in the reaction kettle to be 35-50 ℃;

(E) solvent replacement

Adding a displacement solvent B with the same volume as the aged material in the reaction kettle in the step (D) while stirring in the reaction kettle to displace the residual water, and stirring for 60-180 minutes;

the replacement solvent B is one or a mixture of methanol B, acetone B, n-hexane B or heptane B;

(F) surface modification

Continuously stirring in the reaction kettle, continuously adding the coupling agent B with the same volume as the aged material in the reaction kettle in the step (D), stirring for 60-180 minutes, and performing surface modification to obtain a silicon aerogel precursor B coated with the displacement solvent B and the coupling agent B;

the stirring in the step (E) or the step (F) is to provide rapid forward stirring in the center of the reaction kettle, and baffle plates are provided at the periphery of the center of the reaction kettle;

the coupling agent B is one or a mixture of hexamethyldisilazane B, bis (trimethylsilyl) acetamide B, methoxytrimethylsilane B, dimethoxydimethylsilane B, phenyltriethoxysilane B, phenyltrimethoxysilane B, vinyltrimethoxysilane B, methyltriethoxysilane B and methyltrimethoxysilane B;

(G) preparation of silica aerogel powder B

Placing the silicon aerogel precursor B coated with the displacement solvent B and the coupling agent B into a drying kettle for microwave vacuum drying, filling nitrogen into the drying kettle to remove oxygen until the oxygen content is less than 3%, and keeping the negative pressure at 0.08-0.12 mpa, the temperature at 80-135 ℃, the microwave frequency at 2450MHZ +/-10 MHZ, and obtaining toughened solid silicon aerogel powder B in 50-80 minutes;

the variable parameters and specific values of each example in the process for producing aerogel powder A in examples 1 to 8 are shown in Table 9.

TABLE 9 detailed tables of specific parameters employed in the steps (A) to (G) of the process for producing aerogel powder A in examples 1 to 8

3. The preparation method of the nano titanium oxide composite silica aerogel photocatalyst powder adopted in the silicon-titanium aerogel adsorption and photocatalytic interior wall coating is prepared according to the method recorded in ZL201410311741.1, and comprises the following steps:

passing the silica aerogel particles C through a 300-mesh sieve, and soaking in 20-DEG ammonia water C (the content of liquid ammonia is 20%, and the content of pure water is 80%) for 30-36 h to obtain a material A for later use; the rare earth nitrate C is selected from lanthanum nitrate C, cerium nitrate C or neodymium nitrate C; mixing rare earth nitrate C in a ratio of 1: dissolving the mixture in deionized water C in a weight ratio of 1, and filtering the mixture for later use to obtain a material B;

(II) heating the mixed solution of titanium sulfate C (20% oxide) and 500kg of deionized water C to 75-90 ℃ while stirring, keeping the temperature constant, controlling the stirring speed to be 500-800 r/min, and simultaneously starting ultrasonic vibration, wherein the frequency F of the ultrasonic vibration is 20-35 KHz, and the power density P is 0.3-0.8W/cm²Adding silicon aerogel (material A) at a constant speed within 60-90 minutes, and continuing to react for a period of time after the addition is finished;

(III) adding a proper amount of ammonia C (with the concentration of 20%) to adjust the pH value of the system to 8.0-9.5, then continuously stirring at the stirring speed of 30-80 revolutions per minute, and starting ultrasonic vibration while stirring; reacting for 60-90 minutes to obtain slurry C;

(IV) filtering and washing the slurry C to ensure that the pH value of the slurry C is 7-8, and filtering the material to ensure that the solid content is more than 40%; then, adding 2 times of deionized water C, and simultaneously adding a material B, wherein the weight of the rare earth nitrate C in the material B calculated by oxide is 3-7% of that of the titanium oxide C, the stirring speed is controlled at 500-800 r/min, when the temperature is raised to 75-90 ℃ by stirring, dropwise adding ammonia water C to adjust the pH value to 7-7.5, adding hydrogen peroxide C, and stirring for reacting for 30 minutes; after washing and filtering, collecting and obtaining slurry D when the solid content of the material is more than 40%;

(V) spray-drying the slurry D, wherein the drying inlet temperature is 200-300 ℃, the drying outlet temperature is 100-120 ℃, and then the slurry D enters a tubular oscillation furnace, the heating temperature in the furnace is 450-600 ℃, so that the titanium hydroxide C and the rare earth hydroxide C coated on the surface of the silicon aerogel C are converted into nano-scale anatase titanium oxide C and rare earth oxide C, and finally the silicon aerogel photocatalyst compounded by nano-titanium oxide and rare earth oxide solid solution C is the nano-titanium oxide compound silicon aerogel photocatalyst powder adopted in the mixed material A; the variable parameters and specific values in steps (i) to (v) of the preparation method of the nano titanium oxide composite silica aerogel photocatalyst powder in examples 1 to 8 are shown in table 10.

TABLE 10 detailed tables of specific parameters employed in Steps (I) to (V) of the preparation methods of the nano-titania-silica aerogel photocatalyst powders in examples 1 to 8

Third, performance detection

The coating products of examples 1 to 8 were tested for their formaldehyde-purifying properties, antibacterial properties, and catalytic decomposition of methylene blue, and the specific test criteria and test results are shown in tables 11 and 12.

TABLE 11 inspection bases and inspection results of the purification effects of the products of examples 1 to 8

As can be seen from the data in Table 11, the products of examples 1-8 have a formaldehyde purification effect lasting as high as 70, a formaldehyde purification performance of 88%, and a long-acting catalytic effect on formaldehyde; in addition, good antibacterial performance is also exhibited.

TABLE 12 examination basis and examination result list of methylene blue purification effect of the products of examples 1 to 8 and the existing products

As can be seen from the data in table 12, under the same other conditions, after methylene blue in the system is faded 1 time by the conventional adsorption and photocatalytic coating, methylene blue is added into the system, and the methylene blue cannot be faded; the products in examples 1-8 can enable methylene blue in the system to fade for 1 time, and then methylene blue is added into the system for 7 times, so that the methylene blue can fade, and even if the methylene blue fades for 8 times continuously, the long-acting catalytic effect is achieved.

The product is a long-term effective functional material, the use thickness of the product is below 100 mu m, after 48 hours of decoration, the indoor pollutants can reach the national standard and can be decomposed for a long time, and the product can remove more than 80% of the pollutants in the indoor air through the detection of the China building material industry environment monitoring center.

Although the 8 embodiments of the present invention have been described in detail, the description is only for the preferred embodiments of the present invention and should not be construed as limiting the scope of the present invention. All equivalent changes and modifications made within the scope of the present invention shall fall within the scope of the present invention.

Claims

1. A preparation method of a silicon-titanium aerogel adsorption and photocatalysis interior wall coating is characterized by comprising the following steps: grinding aerogel powder A and a wetting agent A-2 with the weight part of 0.5-2 times of that of the aerogel powder A in a sand mill with the rotating speed of 800-2500 r/min, and then sieving with a 200-1000-mesh sieve to obtain a mixture of the aerogel powder A and the wetting agent A-2 with the particle size of 500-2000 nm;

(2) adding the nano titanium oxide composite silicon aerogel photocatalyst powder and the wetting agent A-1 into a kneading machine, uniformly stirring, and then adding the mixture of the aerogel powder A with the particle size of 500-2000 nm and the wetting agent A-2 obtained in the step (1) into the kneading machine, and uniformly stirring; the added weight part of the aerogel powder A is 0.02-0.25 time of that of the nano titanium oxide composite silicon aerogel photocatalyst powder, and the added weight part of the wetting agent A-1 is 0.5-3 times of that of the nano titanium oxide composite silicon aerogel photocatalyst powder, calculated on the basis of the aerogel powder A before grinding and sieving;

(3) adding a pigment filler A and water A into a kneading machine to be uniformly kneaded, wherein the added weight part of the pigment filler A is 0.5-3 times of the weight part of the nano titanium oxide composite silicon aerogel photocatalyst powder,

(4) mixing and uniformly stirring 1-12 parts by weight of a leveling agent A, 1-20 parts by weight of a dispersing agent A, 1-10 parts by weight of a preservative A, 1-10 parts by weight of a defoaming agent A, 10-50 parts by weight of a styrene-acrylic emulsion A, 5-40 parts by weight of an elastic emulsion A, 5-40 parts by weight of an organic silicon modified acrylic emulsion A, a film-forming assistant A and a thickening agent A, pH regulator A to obtain a mixed material A-2, wherein the pH value of the mixed material A-2 is 7-8.5; in the step (4), the thickening agent A is diluted by 1-50 times of water D before use and is placed for 5-24 hours;

(5) uniformly stirring the mixture obtained in the step (2), the step (3) and the step (4) in a shearing stirrer;

(6) homogenizing the mixture obtained in the step (5) by an emulsification pump, and sieving the emulsified mixture by a 200-300-mesh sieve to obtain the silicon-titanium aerogel adsorption and photocatalysis inner wall coating;

the preparation method of the aerogel powder A comprises the following steps:

(A) preparation of a mixed solution of a silicon source and a solvent

Putting sodium silicate B with the modulus of 3.0-4.0 into a reaction kettle, adding water B with the mass of 1-3 times that of the sodium silicate B for dilution, stirring the reaction kettle at the speed of 80-200 r/min for 30min, and filtering to obtain a sodium silicate solution B;

(B) sol gel

Taking acid A, adding metal salt A and rare earth acid salt A into the acid A, uniformly mixing, and adding into the sodium silicate solution B obtained in the step (A) in a spraying manner; quickly stirring the materials in the reaction kettle at 1200-2000 r/min while spraying, and controlling the pH value of the sodium silicate solution B to be 1.5-3.0 to obtain sol; the acid A is sulfuric acid B, hydrochloric acid B, oxalic acid B or nitric acid B;

(C) gel

Taking sodium hydroxide B or ammonia water B, adding water B to dilute until the pH value is 10-11.5, and adding the mixture into a reaction kettle in a spraying manner; rapidly stirring the materials in the reaction kettle at the speed of 1200-2000 r/min while spraying, and stopping spraying when the pH value of the materials in the reaction kettle is 4.5-5.5 to obtain gel;

(D) aging of

Continuously stirring the mixture in the reaction kettle at a speed of 20-50 r/min for 3-10 hours, aging the material in the reaction kettle, and controlling the temperature of the material in the reaction kettle to be 35-50 ℃;

(E) solvent replacement

Continuously stirring in the reaction kettle for 60-180 min, and simultaneously adding a displacement solvent B with the same volume as the aged material in the reaction kettle in the step (D) to displace the residual water;

(F) surface modification

Continuously stirring in the reaction kettle, and continuously adding the coupling agent B with the same volume as the aged material in the reaction kettle in the step (D); stirring for 60-180 min to obtain a rare earth toughened silicon aerogel precursor B coated with a substitution solvent B and a coupling agent B;

(G) preparation of silica aerogel powder B

Putting the silicon aerogel precursor B into a drying kettle, filling nitrogen into the drying kettle to remove oxygen until the oxygen content in the drying kettle is less than 3%, and then performing microwave vacuum drying on the material in the drying kettle; drying at a negative pressure of 0.08-0.12 mpa and a temperature of 80-135 ℃ in a drying kettle to obtain solid powdery silicon aerogel powder B, wherein the silicon aerogel powder B is aerogel powder A;

the preparation method of the nano titanium oxide composite silicon aerogel photocatalyst powder comprises the following steps:

the preparation method comprises the following steps of (I) passing silicon aerogel particles C through a 300-mesh sieve, and soaking the silicon aerogel particles C in ammonia water C with the liquid ammonia content of 20% and the pure water content of 80% for 30-36 hours to obtain a material A; mixing rare earth nitrate C in a ratio of 1: dissolving the mixture in deionized water C according to the weight ratio of 1, and filtering to obtain a material B;

(II) mixing the required titanium sulfate C with 95 wt% deionized water C to obtain a solution, wherein the weight ratio of the titanium sulfate C to the titanium oxide C is 5%; continuously stirring the solution, heating to 75-90 ℃, keeping constant temperature, adding the material A prepared in the step (I) at a constant speed within 60-90 min, controlling the stirring speed to be 500-800 r/min, and simultaneously starting ultrasonic vibration, wherein the amount of the added material A is determined by the weight of silica aerogel C, and the weight of the silica aerogel C is 0.36-0.5 time of the weight of the titanium sulfate C converted into the titanium oxide C;

(IV) filtering and washing the slurry C, controlling the pH value of the slurry C to be 7-8, and simultaneously enabling the solid content of the filtered and washed slurry C to be more than 40%; then, adding 2 times of deionized water C, and simultaneously adding a material B (the rare earth nitrate C is easy to absorb moisture, which can cause inaccurate measurement, so that the adding amount of the rare earth nitrate C is accurately quantified, the rare earth nitrate C is calculated by rare earth oxide), wherein the weight of the rare earth nitrate C in the material B is 3-7% of the weight of the titanium oxide C by oxide, the stirring speed is controlled at 500-800 r/min, when the temperature is raised to 75-90 ℃ by stirring, dropwise adding ammonia water C to adjust the pH value to 7-7.5, adding hydrogen peroxide C, the adding amount of the hydrogen peroxide C is 10% of the weight of the rare earth nitrate C in the material B by oxide, and stirring and reacting for 30 min; after washing and filtering, collecting and obtaining slurry D when the solid content of the material is more than 40%;

(V) spray drying the slurry D, and then, feeding the dried slurry into a tubular oscillation sintering furnace, wherein the heating temperature in the tubular oscillation sintering furnace is 450-600 ℃, so that the titanium hydroxide C and the rare earth hydroxide C coated on the surface of the silicon aerogel C are converted into a nano-grade anatase titanium oxide C and rare earth oxide C solid solution, and finally, the silicon aerogel photocatalyst compounded by the nano-grade titanium oxide and the rare earth oxide solid solution C is obtained, namely the nano-grade titanium oxide compound silicon aerogel photocatalyst powder.

2. The preparation method of the silicon-titanium aerogel adsorption and photocatalysis interior wall coating according to claim 1, wherein the interior wall coating comprises water A, a mixed material A-1 and a mixed material A-2 in parts by weight, and the weight ratio of the water A: the material mixing method comprises the following steps of (1) mixing A-1, mixing A-2= 1-3: 2-6: 1-3;

the wetting agent A-1 is one or more of methanol A, ethanol A, propanol A, n-butanol A and pentanol A, and the wetting agent A-2 is one or two of ethylene glycol A or propylene glycol A.

3. The preparation method of the silicon-titanium aerogel adsorption and photocatalysis interior wall coating material according to claim 1, wherein the mixed material A-2 comprises, by weight, 1-12 parts of a leveling agent A, 1-20 parts of a dispersing agent A, 1-10 parts of a corrosion inhibitor A, 1-10 parts of a defoaming agent A, 10-50 parts of a styrene-acrylic emulsion A, 5-40 parts of an elastic emulsion A, 5-40 parts of an organosilicon modified acrylic emulsion A, a film-forming assistant A and a thickening agent A, pH regulator A, and the pH value is 7-8.5;

4. The preparation method of the silicon-titanium aerogel adsorption and photocatalysis interior wall coating according to claim 1, characterized in that: the pigment filler A is one or more of zinc oxide A, barium sulfate A, talcum powder A, diatomite A and coarse whiting powder A, and titanium pigment A; the metal salt A is zirconium salt A or aluminum salt A.

5. The preparation method of the silicon-titanium aerogel adsorption and photocatalysis interior wall coating according to claim 1, characterized in that: the solid contents of the styrene-acrylic emulsion A, the elastic emulsion A and the organic silicon modified acrylic emulsion A are more than or equal to 60 percent, and the viscosity is more than or equal to 1000 cps; the metal salt A is zirconium salt A or aluminum salt A.

6. The preparation method of the silicon-titanium aerogel adsorption and photocatalysis interior wall coating according to claim 1, characterized in that: the leveling agent A is a polyether siloxane leveling agent, the effective component of the defoaming agent A is hydrophobic silicon dioxide, and the film-forming additive A is one or more of trimethylpentanediol A, monoisobutyrate A and alcohol ester 12A; the rare earth A acid salt is cerium salt A, yttrium salt A or lanthanum salt A.

7. The preparation method of the silicon-titanium aerogel adsorption and photocatalysis interior wall coating according to claim 1, characterized in that: the dispersant A is an anionic dispersant, and the thickener A is one or two of hydroxyethyl cellulose A and hydroxymethyl cellulose A.

8. The method for preparing the silicon-titanium aerogel adsorption and photocatalysis interior wall coating according to claim 6, wherein the water A and the water B are deionized water.

9. The preparation method of the silicon-titanium aerogel adsorption and photocatalysis interior wall coating according to claim 1, which is characterized in that: in the step (E), the substitution solvent B is one or a mixture of methanol B, acetone B, n-hexane B, or heptane B.