CN114015293A

CN114015293A - Preparation method of building waterproof coating

Info

Publication number: CN114015293A
Application number: CN202111448057.4A
Authority: CN
Inventors: 刘国; 陈强; 张远禄; 熊林
Original assignee: Qingyuan Loubang Building Material Technology Co ltd
Current assignee: Qingyuan Loubang Building Material Technology Co ltd
Priority date: 2021-11-29
Filing date: 2021-11-29
Publication date: 2022-02-08

Abstract

The invention discloses a preparation method of a building waterproof coating, which comprises the steps of preparing composite microspheres with small and uniform particle size, good water stability, good fluidity and high molding rate; preparing a W/O/W multi-system film-forming agent by taking the prepared composite microspheres as a stabilizer and styrene as an oil phase; weighing 40-50 parts of film forming agent, 90-100 parts of water, 100 parts of white cement and 5-10 parts of fly ash, mixing for 0.5h by a mixer, and standing to obtain the waterproof coating; solves the problem of poor waterproof and weather-resistant properties of the traditional waterproof coating particles.

Description

Preparation method of building waterproof coating

Technical Field

The invention relates to the field of building waterproofing, in particular to a preparation method of a building waterproof coating.

Background

The polymer cement (JS) waterproof paint is a novel waterproof material with good waterproof performance, the paint has the characteristics of good durability of cement materials and high strength and high toughness of polymers, and also has the advantages of good cohesiveness, no toxicity, no odor and the like, but at present, the polymer cement waterproof paint also has the problems of poor water resistance, insufficient corrosion resistance, poor weather resistance and short service life in the using process. Aiming at the problems, the invention discloses a novel building waterproof coating which can well solve the problems.

The polymer cement waterproof coating can be divided into two components and a single component, wherein the two components comprise a liquid component and a solid component. The main components of the liquid component are polymer emulsion, and the main components of the solid component are cement, pigment and filler and an auxiliary agent.

After the solid component and the liquid component of the two-component polymer cement waterproof coating are mixed and stirred uniformly according to a certain proportion and coated on a base material, the waterproof coating can be gradually cured to form a coating film with certain strength and toughness along with the volatilization of water in the coating and the proceeding of cement hydration. When the polymer emulsion is mixed with cement and filler, the polymer emulsion particles are uniformly dispersed around the cement and filler. The cement is subjected to hydration reaction under the condition of sufficient water content, so that calcium hydroxide is saturated and crystals are separated out to generate calcium silicate hydrate and ettringite gel, and latex particles enter pores between the gel and the filler along with the calcium hydroxide hydrate and the ettringite gel. With the progress of cement hydration reaction and continuous volatilization of water, the water content in the coating film is reduced, and the latex particles are gradually adhered together to form a continuous emulsion film between pores between the gel and the filler. The emulsion film penetrates through a network which forms a three-dimensional structure between the gel and the filler, so that the gel and the filler are mutually connected and the coating film is endowed with good flexibility. Active groups in polymer molecules and metal ions such as calcium ions, aluminum ions and the like in cement hydration products are subjected to cross-linking reaction to form a bridging action, so that internal stress is effectively buffered, cracks are reduced, and the compactness of a coating film is enhanced.

The film of the waterproof coating related by the invention greatly improves the waterproof performance of the film from two aspects: on one hand, the hydrophobicity of the coating film and water is increased, namely the contact angle of the prepared coating film is close to 180 degrees, and the coating film does not basically wet the inner building material; on the other hand, after the coating is finished, a continuous and uniform coating film is formed on the surface of the building material to prevent the permeation of water molecules, compared with the existing polymer cement waterproof coating, the developed waterproof coating has uniform and compact particle size, can form a very compact coating film on the surface of the building material, can fill in tiny pores between gel and filler under the action of gravity, forms a net structure in the gaps between the coating particles, and is difficult to pass through the coating film of the waterproof coating because external water is usually in an associated state of dozens of molecules. Therefore, the invented coating has excellent water-proofing capability.

Disclosure of Invention

The invention aims to provide a preparation method of a building waterproof coating, which solves the problem of poor waterproof and weather-resistant properties of traditional waterproof coating particles.

A preparation method of a building waterproof coating comprises the following steps:

s1: the composite microsphere with small and uniform particle size, good water stability, good fluidity and high molding rate is prepared by specifically selecting the macromolecular carbohydrate as the shell, simultaneously selecting the macromolecular carbohydrate as the emulsifier, adding the core material of isobutyl triethoxysilane after the solution is emulsified, and then drying and granulating to obtain the composite microsphere.

1) Firstly, weighing 20-25 parts by weight of shell material, dissolving the shell material in 60-70 parts by weight of deionized water, shearing the mixture for 3 minutes by using a high-speed shearing machine, completely dispersing and dissolving the mixture to form emulsion, then adding 5-10 parts by weight of core material, and shearing the mixture for 3 minutes by using the high-speed shearing machine again to form oil-in-water type emulsion; the shell material is preferably one or a combination of more of sodium alginate, beta-cyclodextrin, chitosan or polyvinyl alcohol; the core material is isobutyl triethoxy silane;

2) drying the oil-in-water emulsion to form particles of 40-50 nm by using a spray drying method, wherein the specific drying parameters are as follows: feeding 80-90 deg.C water vapor from the top of the dryer, spraying the prepared emulsion under 0.2MPa with a nozzle, dispersing the emulsion into 80-100 micrometer droplets, rapidly vaporizing the droplet surface to form 40-50 nanometer composite microspheres, and collecting the composite microspheres with a dust remover built in the dryer; the water content of the dried microspheres is less than 20%, and the contact angle of the dried composite microspheres is increased to about 150 ℃;

s2: the composite microsphere prepared by the method is used as a stabilizer, styrene is used as an oil phase, and a W/O/W multiple system is prepared, wherein the specific process comprises the following steps;

1) adding 0.5 part of composite microspheres into 10 parts of styrene by weight, and performing ultrasonic dispersion to obtain a uniform composite microsphere dispersion liquid;

2) adding 0.2 part by weight of 12 sodium alkyl benzene sulfonate into 100 parts by weight of deionized water, and dissolving in a water bath at 90 ℃ to obtain a sodium alkyl benzene sulfonate aqueous solution;

3) adding 2-5 parts by weight of deionized water and 2-5 parts by weight of anhydrous methanol into the composite microsphere dispersion liquid, and generating W/O initial emulsion after ultrasonic treatment in a water bath at 0-4 ℃;

4) and then pouring the obtained W/O primary emulsion into sodium alkyl benzene sulfonate aqueous solution, mechanically stirring to obtain W/O/W multiple emulsion, then transferring the multiple emulsion into a three-neck flask, introducing nitrogen for 15 minutes to remove oxygen, heating in a water bath at 65 ℃, and mechanically stirring to react for 24 hours.

S3: preparing a waterproof coating by using the film forming agent prepared by the method;

weighing 40-50 parts of film forming agent, 90-100 parts of water, 100 parts of white cement and 5-10 parts of fly ash, mixing for 0.5h by a mixer, and standing to obtain the waterproof coating.

When cement is mixed with a film-forming agent, a continuous coating film is formed which is composed mainly of a polymer film and which is formed by coating unhydrated cement or the like.

The invention uses the coating technology to prepare a novel building waterproof coating, firstly, although the isobutyl triethoxysilane can directly enhance the compatibility between inorganic materials and organic materials, the isobutyl triethoxysilane is easy to hydrolyze in water, thus greatly limiting the use of the isobutyl triethoxysilane; the invention uses special material to coat isobutyl triethoxy silane to form oil-in-water emulsion, which is dehydrated to form hydrophobic layer. Secondly, in order to enhance the stability of the oil-in-water type emulsion and make the particle size of the emulsion more uniform, styrene is used as an oil phase, a methanol solution is used as an external water phase and an internal water phase, and composite microspheres are used as a stabilizer to prepare the water/(stabilizer/styrene/stabilizer)/water type multilayer dispersion emulsion.

When it is used as a waterproof coating material on cement; firstly, the emulsion wraps inorganic filler particles such as cement, and with the volatilization of water in the coating, the polymer emulsion particles are dehydrated, deformed and bonded together on one hand, and on the other hand, the polymer emulsion particles can generate hydration reaction when meeting the cement, and cement hydration products, unhydrated fillers and high molecular polymers are interwoven into a waterproof coating structure. More importantly, when the multiple emulsion compound cement is used, because the emulsion has uniform particle size and cannot generate agglomeration, after the emulsion is contacted with the uneven cement surface, the gap on the contact surface with the cement can be filled, and the formed film is compact and uniform and has no gap when the film is self-leveled on the uneven surface; in addition, as the moisture on the surface of the film and the material on the surface of the composite microsphere volatilize and dissipate, the hydrophobicity of the surface of the microsphere is further enhanced. Thereby having great waterproof performance of the waterproof coating.

Moreover, in order to greatly improve the stability of the emulsion, the composite microspheres prepared by the scheme are used as a stabilizer to prepare a multiple emulsion, the inner water phase droplets are wrapped in the oil phase droplets, and then the oil phase droplets are dispersed in a continuous water phase (deionized water and methanol), in this case, the composite microspheres are well dispersed in the emulsion, meanwhile, the emulsion is also separated by the water film and the composite microspheres dispersed between the water film and the oil film, when the water drops or oil drops are too large or uneven, the initial emulsion can still exist stably after secondary emulsification through slight stirring, the structure of the initial emulsion is retained, the sizes of the water drops and the oil drops can be redistributed, and the sizes of the water drops or the oil drops are adjusted through the content of the composite microspheres.

Drawings

FIG. 1 is an SEM (scanning electron microscope) image of an undried composite microsphere liquid drop in the invention;

FIG. 2 is an SEM (scanning electron microscope) image of the composite microspheres after spray drying in the invention;

FIG. 3 is an XPS spectrum of composite microspheres after spray drying according to the present invention;

FIG. 4 is a contact angle of a droplet of composite microspheres of the present invention without drying;

FIG. 5 is a contact angle of a water drop on the surface of a composite microsphere after spray drying according to the present invention;

FIG. 6 is an optical micrograph of a multiple composite emulsion system formed from composite microspheres according to the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

The specifications and sources of the chemical reagents used in the present invention are detailed below:

main raw materials for experiment

Raw materials	Specification of	Source	Others
				Isobutyl triethoxy silane	98％	Buddha mountain roadNing (medicine for curing rheumatism)
Heavy calcium carbonate	800 mesh	Jia Bao Li chemical industry group provides
				Mica powder	800 mesh	Jia Bao Li chemical industry group provides
Talcum powder	800 mesh	Jia Bao Li chemical industry group provides
				Calomel	800 mesh	Jia Bao Li chemical industry group provides
Styrene (meth) acrylic acid ester	Chemical purity	TIANJIN DAMAO CHEMICAL REAGENT FACTORY
				Azobisisobutyronitrile (AIBN)	Chemical purity	SINOPHARM CHEMICAL REAGENT Co.,Ltd.
Sodium alginate	Chemical purity	Henan Rongshen chemical Co., Ltd
				Beta-cyclodextrin	Chemical purity	ZIBO QIANHUI BIOTECHNOLOGY Co.,Ltd.
Chitosan	Chemical purity	Shandong Onkang Biotech Co Ltd
				Polyvinyl alcohol	Chemical purity	Shenyang Longxing Wei trade company Ltd
Anhydrous methanol	Chemical purity	Nanjing chemical reagent
				White cement	Chemical purity	The special cement building material for Yunyan hasLimited company
Fly ash	Chemical purity	Guangzhou Jialiang mineral products Co Ltd

The main quality indexes of the white cement are as follows:

the main quality indexes of the fly ash are as follows:

the first embodiment is as follows:

s1: preparing a composite microsphere emulsion;

1) weighing 20 parts of shell material according to parts by weight, dissolving the shell material in 60-70 parts of deionized water, shearing the mixture for 3 minutes by using a high-speed shearing machine, completely dispersing and dissolving the mixture to form emulsion, then adding 5 parts of core material, and shearing the mixture for 3 minutes by using the high-speed shearing machine again; the shell material is preferably chitosan; the core material is isobutyl triethoxy silane;

2) using a spray drying method, the specific drying parameters are as follows: feeding 80-90 deg.C water vapor from the top of the dryer, spraying the prepared emulsion under 0.2MPa with a nozzle, dispersing the emulsion into 80-100 micrometer droplets, rapidly vaporizing the droplet surface to form 40-50 nanometer composite microspheres, and collecting the composite microspheres with a dust remover built in the dryer;

s2: preparing a W/O/W multiple system, wherein the specific process comprises the following steps;

weighing 40 parts of film forming agent, 100 parts of water, 120 parts of white cement and 10 parts of fly ash according to parts by weight, mixing for 0.5h by a mixer, and standing to obtain the waterproof coating.

Example two:

except the following steps are different from the first embodiment, the other steps refer to the first embodiment:

s1: preparing a composite microsphere emulsion;

1) weighing 20 parts of shell material according to parts by weight, dissolving the shell material in 60-70 parts of deionized water, shearing the mixture for 3 minutes by using a high-speed shearing machine, completely dispersing and dissolving the mixture to form emulsion, then adding 10 parts of core material, and shearing the mixture for 3 minutes by using the high-speed shearing machine again; the shell material is chitosan; the core material is isobutyl triethoxy silane;

The comparison between the first embodiment and the second embodiment shows that the forming rate of the composite microspheres can be improved by increasing the content of the core material, and the comprehensive performance of the product can be improved.

Example three:

s1: preparing a composite microsphere emulsion;

1) weighing 20 parts of shell material according to parts by weight, dissolving the shell material in 60-70 parts of deionized water, shearing the mixture for 3 minutes by using a high-speed shearing machine, completely dispersing and dissolving the mixture to form emulsion, then adding 10 parts of core material, and shearing the mixture for 3 minutes by using the high-speed shearing machine again; the shell material is a composition selected from sodium alginate, beta-cyclodextrin, chitosan and polyvinyl alcohol; the core material is isobutyl triethoxy silane; sodium alginate, beta-cyclodextrin, chitosan or polyvinyl alcohol are compounded according to the weight part ratio of 1:1:1: 1;

The second embodiment is compared with the third embodiment to show that when the amount of the core material is kept unchanged, the shell material is compounded to further improve the forming rate of the composite microspheres and improve the comprehensive performance of the product.

Example four:

s1: preparing a composite microsphere emulsion;

weighing 50 parts of film forming agent, 100 parts of water, 120 parts of white cement and 10 parts of fly ash according to parts by weight, mixing for 0.5h by a mixer, and standing to obtain the waterproof coating.

The comparison between the third example and the fourth example shows that when the waterproof material is prepared, the content of the film forming agent is properly increased, so that the waterproof effect of the waterproof coating and the comprehensive performance of the product are improved.

Example five:

s1: preparing a composite microsphere emulsion;

1) weighing 20 parts of shell material according to parts by weight, dissolving the shell material in 60-70 parts of deionized water, shearing the mixture for 3 minutes by using a high-speed shearing machine, completely dispersing and dissolving the mixture to form emulsion, then adding 5 parts of core material, and shearing the mixture for 3 minutes by using the high-speed shearing machine again; sodium alginate is selected as a shell material, and isobutyl triethoxysilane is selected as a core material;

weighing 40 parts of film forming agent, 90 parts of water, 100 parts of white cement and 5 parts of fly ash according to parts by weight, mixing for 0.5h by a mixer, and standing to obtain the waterproof coating.

Example six:

s1: preparing a composite microsphere emulsion;

1) weighing 25 parts of shell material according to parts by weight, dissolving the shell material in 60-70 parts of deionized water, shearing the mixture for 3 minutes by using a high-speed shearing machine, completely dispersing and dissolving the mixture to form emulsion, then adding 10 parts of core material, and shearing the mixture for 3 minutes by using the high-speed shearing machine again; sodium alginate is selected as the shell material; the core material is isobutyl triethoxy silane;

Example seven:

s1: preparing a composite microsphere emulsion;

1) weighing 22 parts of shell material according to parts by weight, dissolving the shell material in 60-70 parts of deionized water, shearing the mixture for 3 minutes by using a high-speed shearing machine, completely dispersing and dissolving the mixture to form emulsion, then adding 8 parts of core material, and shearing the mixture for 3 minutes by using the high-speed shearing machine again; the shell material is a composition selected from sodium alginate, beta-cyclodextrin, chitosan and polyvinyl alcohol; the core material is isobutyl triethoxy silane; sodium alginate, beta-cyclodextrin, chitosan or polyvinyl alcohol are compounded according to the weight part ratio of 1:1:1: 1;

weighing 45 parts of film forming agent, 95 parts of water, 110 parts of white cement and 8 parts of fly ash according to parts by weight, mixing for 0.5h by a mixer, and standing to obtain the waterproof coating.

The comparison between the fifth example and the sixth example shows that when the formula of the waterproof coating is configured, the contents of the core material, the shell material and the film forming agent cannot be simply increased, and the molding rate of the composite material can be increased only by considering the mixture ratio.

Comparative example one:

the coating adopts styrene-acrylic and cement, and the formula is referred as follows:

comparative example two:

the coating adopts VAE + cement, and the formula is referred as follows:

raw materials	Mass portion of
		VAE emulsions	200-300
Wetting agent	1
		Dispersing agent	2.0
Mixed filler	150-200
		Defoaming agent	0.5
Thickening agent	5
		Film forming aid	10-20
Aqueous ammonia	Proper amount of
		Mildew-proof preservative	2

The implementation effect is as follows:

wherein, after the sodium alginate, the beta-cyclodextrin, the chitosan, the polyvinyl alcohol and the deionized water in the shell material are mixed according to a certain proportion, the viscosity of the solution is 6.8cP, the particle size of the formed emulsion is less than 1 micron, and the obtained emulsion has better fluidity and water solubility.

Drying the obtained emulsion by spray drying method to obtain the product shown in FIG. 2, wherein the obtained composite microsphere has uniform particle diameter, i.e. SiO is wrapped by the shell material₂Particles; as shown in FIG. 5, the surface of the dried composite microsphere is made of super-hydrophobic material, and the contact angle thereof can reach 150 degrees. As shown in fig. 4, when the coated liquid is placed in water, the contact angle of the liquid drop will decrease rapidly to slightly more than 90 °.

The composite microspheres are prepared by using a spray drying method, a plurality of factors need to be considered in the selection of shell materials, sodium alginate, beta-cyclodextrin, chitosan and polyvinyl alcohol are used as the shell materials because after a compound of the sodium alginate, the beta-cyclodextrin, the chitosan and the polyvinyl alcohol are stirred with water, the emulsion has small particle size, good stability and good fluidity and water solubility, and can be quickly emulsified after being stirred for 10-15 minutes, the particle size of the generated emulsion droplets is uniform, the isobutyl triethoxysilane is gradually coated by the shell materials along with the gradual addition of the core materials, the coating rate is very high, the coating can be basically coated, the thickness of the shell layer is determined by the amount of the added shell materials, and the size of the core is directly related to the stirring rate.

In the spray drying process, the shell material is compounded in water, an O/W type emulsion is formed after stirring, the diameter of the formed O/W type emulsion is about 30 micrometers generally, after the isobutyl triethoxysilane core material is added, the diameter of emulsion liquid drops can be enlarged to about 80 micrometers, the emulsion liquid drops are conveyed into a dryer through a pump, after the emulsion liquid drops are mixed with 80-90 ℃ medium-high temperature air, partial moisture on the surfaces of the composite microspheres can be taken away, the composite microspheres shrink, and the liquid drops can be converted into solids after losing moisture.

Spray drying temperature and nozzle pressure can greatly affect product quality, mainly including two aspects: 1) atomization is a process of dispersing emulsion into tiny droplets under the action of an atomizer, if the size of the droplets is not uniform, large droplets are not completely dried, but small droplets are excessively dried, and the size of the droplets obtained by selecting a nozzle with 0.2MPa is very uniform. 2) The water vapor with the temperature of 80-90 ℃ is mixed with the liquid drops to generate mass transfer and heat transfer, the water in the liquid drops is quickly evaporated into a gas phase after the liquid drops absorb the heat of hot air, the liquid drops are dried to form solid particles, the drying process is mainly a constant-speed drying stage, and the surface of the composite microsphere is uneven due to too high temperature at the stage, so that the contact angle of the surface of the composite microsphere is seriously influenced.

Preparation of multiple emulsion: the stability of the emulsion prepared is best when the composite microspheres are capable of being wetted by both the aqueous phase and the oil phase, i.e., the particles have proper wettability. When the contact angle is slightly larger than 90 °, the particles adsorbed on the interface are more immersed in the oil phase, and thus the water-in-oil emulsion is more easily formed. When the contact angle is slightly less than 90 °, the particles adsorbed on the interface are more immersed in the aqueous phase and thus more easily form an oil-in-water emulsion. When the contact angle of the surface of the nano silicon dioxide particles is slightly larger than 90 degrees, the stabilizing effect on the W/O initial emulsion is best.

SEM electron micrographs of the undried composite microsphere droplets and the spray-dried composite microspheres are shown in fig. 1 and 2, and the undried composite microspheres have a large amount of moisture absorbed by the shell material due to the coating of the shell material, resulting in a large particle size, whereas when the composite microspheres are dried, the shell material loses moisture, and the shell material and the core material are fused together, so that the formed composite microspheres have a uniform particle size and smooth surfaces.

The particle size of the undried composite microsphere particles is larger, the contact angle is about 100 degrees, multiple emulsion is easy to form, and on one hand, the formed multiple emulsion is stable; on the other hand, because the emulsion droplets are multi-layer emulsion, the emulsion droplets have extremely strong compatibility with water layers or oil layers, and no gap is formed between the coating and the coated object, so that water is infiltrated.

As shown in fig. 3, 4 and 5, it can be seen from XPS spectra that the composite microspheres mainly contain Si element, O element and C element, and the presence of a large amount of C element on the surface confirms that an organic group is indeed introduced to the surface of the composite microspheres, and the contact angle of the surface of the composite microspheres changes dramatically with the loss of moisture on the surface of the composite microspheres, and a strong hydrophobic layer is formed after drying.

The optical micrograph of the multiple complex emulsion system is shown in FIG. 6, from which it is apparent that a plurality of small droplets are wrapped in large droplets to form a W/O/W multiple structure. This shows that the microspheres have good stabilizing effect on the initial W/O emulsion, and after the secondary emulsification, the initial emulsion can still exist stably, and the structure of the initial emulsion is retained. In w/o/w multiple emulsions stabilized with conventional emulsifiers, the diffusion of emulsifier molecules between the internal and external aqueous phases is the most important cause of the destabilization of the emulsion. In the emulsion synthesized by the invention, solid particles are firmly adsorbed on an oil-water interface, and the separation effect is realized among liquid drops, so that the solid particles are not easy to migrate among several phases after the W/O/W composite emulsion is formed, and the emulsion shows good stability, which is very important for improving the subsequent waterproof performance of products.

And (3) product testing: the method is carried out according to GB/16777 and 2008.

Change in tensile Strength of 7 d-aged coating film after various durability treatments

Change in tensile Strength of 28 d-aged coating film after various durability treatments

Change in tensile Strength of 120 d-aged coating film after various durability treatments

Change in elongation at break of 120 d-aged coating film after various durability treatments

All the coating films were subjected to water immersion treatment, and the tensile strength was somewhat lowered, which was attributed to plasticization by water absorbed into the coating films. After immersion in water, the elongation at break was greatly improved.

The molecular structure of the polymer in the emulsion has a certain amount of hydrophilic groups. In the process of polymerization

Since the emulsifier or protective colloid used in the process also has a certain affinity for water, the coating film is usually soaked in water and absorbs water, so that the coating film swells, softens, and the like. The problem is also the common problem of the traditional emulsion type coating film and the root cause of the leakage of the traditional waterproof coating.

Compared with the traditional emulsion waterproof coating and the waterproof coating developed by the invention, the change values of the breaking tensile strength and the breaking tensile rate after being treated by various media are smaller than those of the traditional coating, which shows that the swelling effect of the coating is obviously smaller.

In addition, in the first to seventh examples, the water impermeability (0.3MPa, 30min) was acceptable when tested for 120 days after the treatment of each medium. Compared with the traditional waterproof coating, the waterproof coating developed by the invention has better waterproof performance and weather resistance.

The above description is only exemplary of the present invention, and the structure is not limited to the above-mentioned shapes, and any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A preparation method of a building waterproof coating is characterized by comprising the following steps,

s1: preparing composite microspheres with small and uniform particle size, good water stability, good fluidity and high molding rate, selecting macromolecular carbohydrate as a shell and an emulsifier, emulsifying the solution, adding a core material of isobutyl triethoxysilane, drying and granulating to obtain the composite microspheres:

1) firstly, weighing 20-25 parts by weight of shell material, dissolving the shell material in 60-70 parts by weight of deionized water, shearing the shell material for 3 minutes by using a high-speed shearing machine, completely dispersing and dissolving the shell material to form emulsion, then adding 5-10 parts by weight of core material, wherein the core material is isobutyl triethoxysilane, and shearing the core material for 3 minutes by using the high-speed shearing machine again to form oil-in-water emulsion;

4) pouring the obtained W/O primary emulsion into sodium alkyl benzene sulfonate aqueous solution, mechanically stirring to obtain W/O/W multiple emulsion, then transferring the multiple emulsion into a three-neck flask, introducing nitrogen for 15 minutes to remove oxygen, heating in a water bath at 65 ℃, and mechanically stirring to react for 24 hours;

2. The method for preparing the architectural waterproof coating according to claim 1, characterized in that: the shell material is preferably one or a combination of more of sodium alginate, beta-cyclodextrin, chitosan or polyvinyl alcohol.

3. The method for preparing the architectural waterproof coating according to claim 1, characterized in that: the coating comprises, by weight, 50 parts of a film forming agent, 100 parts of water, 120 parts of white cement and 10 parts of fly ash.