A composition for a breathable waterproof paint, a paint, and a preparation method and application thereof

Abstract

The application provides a breathable waterproof coating composition, a coating and a preparation method and application thereof, and relates to the technical field of high polymer materials.The breathable waterproof coating composition comprises a main agent and an auxiliary agent, and the main agent comprises, in mass parts, 290-350 parts of a silicone propylene core-shell emulsion, and 400-500 parts of a filler, wherein the silicone propylene core-shell emulsion is prepared by core-shell emulsion polymerization reaction of raw material components including an acrylic core layer monomer and an organic silicon shell layer monomer, and the filler is a compound filler composed of micron, submicron and nanometer fillers, and the particle size D50 is 200nm-50mu m.Under the premise of ensuring waterproofness of the coating film, the application significantly improves the breathability of the coating film, and good flexibility is given to the coating film.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of high polymer materials, in particular to a composition for air-permeable waterproof coating, a coating and a preparation method and application thereof. BACKGROUND

[0002] Waterproof coating is widely used in waterproofing and moisture-proofing of building walls and floors, underground garages, pools, etc., especially for building exterior walls. GB55030 requires that the exterior wall needs to be waterproofed (the waterproof layer structure is compact, impermeable to water and air). However, JGJ144 requires that the waterproof layer outside the thermal insulation layer should have a certain air permeability, i.e. the wet flow density is greater than or equal to 0.85 g / (m 2 ·h). This requires that the waterproof coating not only has impermeability to water, but also has a certain air permeability. However, most of the waterproof coatings on the market have no air permeability or poor air permeability, and when the environmental temperature and humidity change, the vapor pressure is unbalanced, which can cause condensation, coating bulging and even cracking on the building exterior wall. At present, the most common strategy is to balance the impermeability and air permeability of the coating film by adjusting the porosity.

[0003] The prior art CN105331239A discloses a breathable waterproof coating and a preparation method thereof, wherein a self-made micron waterproof powder is used, and is compounded with a high molecular resin and other inorganic powders to prepare a waterproof coating with a microporous structure. The filler is a compounded filler composed of micron, submicron and nanometer fillers, which gives the coating both waterproof and air-permeable functions. However, the pigment volume concentration (PVC) of the waterproof coating is high, and under high PVC, the pigment particles are filled between the polymer chains, limiting the movement ability of the molecular chains, resulting in poor toughness of the coating film. The coating film with poor flexibility cannot absorb stress through elastic deformation, thereby cracks can be generated at the stress concentration, limiting the practical application of the waterproof coating.

[0004] Therefore, in addition to balancing the air permeability and water permeability, the flexibility of the waterproof coating should also be considered. SUMMARY

[0005] The present application provides a composition for air-permeable waterproof coating, which is prepared by compounding the chemical structure design of the silicone-acrylate core-shell emulsion and the physical pore regulation of the filler, to realize the precise regulation of the waterproofness and air permeability of the coating film, avoid the entry of liquid water from the outside into the building wall, and allow the internal moisture to be discharged outward, thereby giving the coating film good liquid water barrier and water vapor transmission functions. At the same time, the coating film has good flexibility, can effectively adapt to the deformation of the base layer, and avoid functional failure caused by physical damage.

[0006] Another object of the present application is to provide a preparation method of the breathable waterproof coating.

[0007] Another object of the present application is to provide a breathable waterproof coating.

[0008] Still another object of the present application is to provide an application of the breathable waterproof coating in waterproof and moisture-proof buildings.

[0009] In the first aspect, the present application provides a composition for the breathable waterproof coating, which comprises a main agent and an auxiliary agent, wherein the main agent comprises the following components in mass fraction: 290-350 parts of a silicone-acrylate core-shell emulsion, 400-500 parts of a filler.

[0010] The silicone-acrylate core-shell emulsion is prepared by a core-shell emulsion polymerization reaction using acrylate core layer monomers and silicone shell layer monomers, wherein the acrylate core layer monomers are acrylate monomers containing -OH and -COOH groups, and the silicone shell layer monomers are silicone monomers having a Si-O-Si backbone.

[0011] The filler is a composite filler composed of micron, sub-micron and nano fillers, and the filler has a particle size D50 of 200 nm-50 μm.

[0012] According to the composition for the breathable waterproof coating, preferably, the silicone content of the silicone-acrylate core-shell emulsion is 5-10%, and the particle size is 50-150 nm.

[0013] According to the composition for the breathable waterproof coating, preferably, the raw material components of the silicone-acrylate core-shell emulsion further comprise functional monomers, the functional monomers are disulfide bond-containing monomers, the content of the acrylate core layer monomers is 70-80 wt%, the content of the silicone shell layer monomers is 15-25 wt%, and the content of the functional monomers is 2-8 wt%.

[0014] According to the composition for the breathable waterproof coating, preferably, the acrylate core layer monomers are selected from one or more of butyl acrylate (BA), acrylic acid (AA) and hydroxyethyl acrylate (HEA).

[0015] And / or, the silicone shell layer monomers are selected from one or more of octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), dodecamethylcyclohexasiloxane (D6), gamma-methacryloxytrimethoxysilane (KH-570) and gamma-aminopropyltriethoxysilane (KH-550).

[0016] And / or, the functional monomers are selected from one or more of bis(acryloyloxyethyl) disulfide (BADS), dimethyl acrylate disulfide (DSDMA) and 2-carboxy-allyl disulfide methacrylic acid (CADMA).

[0017] According to the application, the composition for the air-permeable waterproof coating is provided, preferably, the filler comprises solid filler and porous filler.

[0018] According to the application, the composition for the air-permeable waterproof coating is provided, preferably, the solid filler is selected from one or more of alumina, silica, barium sulfate or calcium carbonate.

[0019] According to the application, the composition for the air-permeable waterproof coating is provided, preferably, the porous filler is selected from one or more of diatomite, expanded perlite, porous alumina or white carbon black.

[0020] According to the application, the composition for the air-permeable waterproof coating is provided, preferably, the auxiliary agent comprises 0.5-1 part of cellulose ether, 2.0-6.0 parts of dispersing agent, 3.0-8.0 parts of defoaming agent, 1.0-4.0 parts of bactericide, 1.0-4.0 parts of mildew-proof agent and 0.5-1.5 parts of thickening agent.

[0021] In the second aspect, the application further provides a preparation method of the air-permeable waterproof coating, wherein the main agent, the auxiliary agent and water in the composition for the air-permeable waterproof coating are mixed to obtain the air-permeable waterproof coating, preferably, the method comprises the following steps:

[0022] S1. water is added into a stirred tank, and the cellulose ether is added and mixed uniformly under stirring;

[0023] S2. the dispersing agent, the defoaming agent, the bactericide, the mildew-proof agent and 1 / 3-1 / 2 of the silicone-acrylate core-shell emulsion are sequentially added and stirred uniformly;

[0024] S3. the filler is added and stirred uniformly, then the remaining silicone-acrylate core-shell emulsion is added, the thickening agent is added after stirring uniformly, and the air-permeable waterproof coating is obtained after stirring uniformly.

[0025] In the third aspect, the application further provides the air-permeable waterproof coating prepared by the preparation method of the air-permeable waterproof coating.

[0026] In the fourth aspect, the application further provides the application of the air-permeable waterproof coating in waterproof and moisture-proof buildings.

[0027] Beneficial effects:

[0028] The application provides a composition for air-permeable waterproof paint, which is prepared by compounding a silicone-acrylate core-shell emulsion and fillers according to the physical pore regulation, and the silicone-acrylate core-shell emulsion is prepared by the chemical structure design of the core-shell, the core layer keeps the micropore connectivity, and the shell layer is densified to realize the air permeability and waterproof function, the physical pore regulation of the fillers can significantly improve the air permeability of the coating film under the premise of ensuring the water impermeability, the polymer particles in the silicone-acrylate emulsion are wrapped on the surface of the filler particles in the form of chain segment diffusion and entanglement, and a continuous film is formed after water volatilization, so that the coating film has good flexibility.

[0029] The application overcomes the defects of the prior art waterproof paint, such as the fact that the water impermeability and air permeability cannot be simultaneously considered, and the flexibility is insufficient, the water vapor transmission rate is as high as 148-200 g / (m 2 ·24h), no liquid water is leaked for 2-4h under 1m water column, the coating film has good flexibility and adhesion, the elongation at break is 105-135%, the adhesion strength is 1.0-1.4Mpa, the coating film can be applied to interior wall moisture-proof, exterior wall air-permeable waterproof, ancient building repair and protection and other projects, and has high application value. DETAILED DESCRIPTION

[0030] The following examples are used to illustrate the application, but are not used to limit the scope of the application. If the specific technology or condition is not indicated in the examples, the technology or condition is carried out according to the technology or condition described in the literature in the field, or according to the product instruction. If the manufacturer of the reagent or instrument is not indicated, the reagent or instrument is a conventional product that can be purchased through a regular channel.

[0031] The raw materials mentioned in the examples and comparative examples of the application are as follows:

[0032] Butyl acrylate (BA): Jinan Shidatuda Chemical Co., Ltd.

[0033] Hydroxyethyl acrylate (HEA): Shandong Jinyueyuan New Material Co., Ltd.

[0034] Acrylic acid (AA): Guangdong Tianlong Ink Co., Ltd.

[0035] Bis(acryloyloxyethyl) disulfide (BADS): Shanghai Aladdin Biochemical Technology Co., Ltd.

[0036] Octamethylcyclotetrasiloxane (D4): Shandong Dayi Chemical Co., Ltd.

[0037] Gamma-methacryloxytrimethoxysilane (KH-570): Shanghai Kaixin Chemical Co., Ltd.

[0038] Gamma-Al2O3 (D50=250nm): Ningbo Yutian Material Technology Co., Ltd.

[0039] Alpha-Al2O3 (D50=5 μm): Nanjing Tianxing New Material Co., Ltd.

[0040] Alpha-Al2O3 (D50=42 μm): Nanjing Tianxing New Material Co., Ltd.

[0041] Fumed silica N-20ST (D50=20 nm): Wacker Chemie (China) Co., Ltd.

[0042] In the examples and comparative examples of the present application, the same raw materials were used unless otherwise specified.

[0043] In a specific embodiment, the present application provides a composition for a breathable waterproof coating, which comprises a main agent and an auxiliary agent, the main agent comprising the following components in mass fraction: a silicone-acrylate core-shell emulsion 290-350 parts, a filler 400-500 parts,

[0044] The silicone-acrylate core-shell emulsion is prepared by core-shell emulsion polymerization of raw material components including an acrylate core layer monomer, a silicone shell layer monomer, and a functional monomer,

[0045] The acrylate core layer monomer is an acrylate monomer containing -OH and -COOH groups, and the silicone shell layer monomer is a silicone monomer having a Si-O-Si backbone and methyl side chains.

[0046] The filler is a compounded filler composed of micron, sub-micron, and nano fillers, and the filler particle size D50 is 200 nm-50 μm.

[0047] It should be noted that:

[0048] In the silicone-acrylate core-shell emulsion, the acrylate core layer monomer and the functional monomer are polymerized to form a core, and the silicone shell layer monomer is polymerized to form a shell layer. The acrylate core layer monomer can impart good flexibility to the coating film. The -OH and -COOH groups contained in the acrylate core layer monomer form a three-dimensional network structure during film formation, which can form water vapor transmission channels and improve the breathability. The silicone shell layer monomer has a low surface energy (18-24 mN / m) due to the Si-O-Si backbone and methyl side chains, and the dense shell layer can block liquid water, but the dense layer allows water vapor molecules to pass through due to the intermolecular gaps of the silicone, ensuring breathability under waterproof conditions.

[0049] In some specific embodiments, the functional monomer is a disulfide bond-containing monomer. The functional monomer is responsive to humidity due to the disulfide bond, i.e., high humidity causes the disulfide bond to hydrolyze and break, increasing the porosity of the coating film and increasing the breathability, and low humidity causes the disulfide bond to recombine, reducing the porosity of the coating film and reducing the breathability. The humidity corresponds to dynamic crosslinking of the coating film, which can self-adaptively adjust the porosity and promote the balance between waterproofness and breathability.

[0050] The specific type of the acrylic core layer monomer, the silicone shell layer monomer and the functional monomer raw material in the silicone-acrylate core-shell emulsion is not specifically limited in the present application, as long as it has the corresponding group structure to achieve the effect of the present application.

[0051] The silicone-acrylate core-shell emulsion realizes the functions of air permeability and water resistance through the chemical structure design of core-shell, the microporous connectivity of the core layer and the densification of the shell layer. Meanwhile, after the scientific compounding of the silicone-acrylate core-shell emulsion and the filler, the polymer particles in the silicone-acrylate emulsion are wrapped on the surface of the filler particles in the form of chain segment diffusion and entanglement, and a continuous film is formed after the evaporation of water. The filler dispersed in the silicone-acrylate core-shell emulsion can enhance the water resistance through the physical barrier and interfacial adsorption. The physical barrier fills the pores in the film with the filler, reducing the through channels. The interfacial adsorption forms hydrogen bonds or chemical bonds between the hydroxyl groups on the surface of the filler and the emulsion polymer, improving the cohesive strength of the film and preventing water stress damage.

[0052] In the composition for air-permeable waterproof coating of the present application, the silicone-acrylate core-shell emulsion (chemical structure design) is compounded with the filler (physical pore regulation) to realize the precise regulation of water resistance and air permeability, avoid the entry of water from the outside into the wall of the building, and enable the internal moisture to be discharged to the outside, thereby endowing the coating film with good liquid water blocking and water vapor permeation functions, ensuring that the wall has good breathing function under the premise of being water-resistant, has good flexibility, and avoids the phenomena of wall surface condensation, coating bulging and even cracking caused by the imbalance of vapor pressure due to changes in environmental temperature and humidity.

[0053] In order to achieve better physical pore regulation effect, in some specific embodiments, the filler is a compounded filler composed of micron, submicron and nanoscale fillers. The selection of micron, submicron and nanoscale fillers with multiple particle size gradients facilitates the construction of a controllable physical pore network, forming a coating film network with a pore size of 0.3-100 nm, thereby realizing the effect of water vapor molecule permeation but blocking liquid water penetration.

[0054] For example, the micron-scale particle size can be D50=40-50 μm, the submicron-scale particle size can be D50=2-8 μm, and the nanoscale particle size can be D50=200-300 nm.

[0055] The silicon content of the silicone-acrylate core-shell emulsion is the content of the silicone shell layer. Too low silicon content affects the densification of the shell layer, and too high silicon content makes the shell too dense, affecting the formation of water vapor molecule permeation gaps. In order to achieve a balance between water resistance and air permeability, in some specific embodiments, the present application also preferably controls the silicon content of the silicone-acrylate core-shell emulsion to be 5-10%, and the particle size to be 50-150 nm.

[0056] In some embodiments, in order to control the preparation of the specific silicone-acrylate core-shell emulsion of the present application, the content of the acrylate core layer monomer (a) in the raw material components of the silicone-acrylate core-shell emulsion is 70-80 wt%, the content of the silicone shell layer monomer (b) is 15-25 wt%, and the content of the functional monomer (c) is 2-8 wt%.

[0057] The content of each monomer component is based on the total weight of the raw material components.

[0058] In some embodiments, the acrylate core layer monomer mentioned in the present application may, for example, be selected from one or more of butyl acrylate, acrylic acid, and hydroxyhexyl acrylate.

[0059] In some embodiments, the silicone shell layer monomer mentioned in the present application may, for example, be one or more of octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, γ-methacryloyloxytrimethoxysilane, and γ-aminopropyltriethoxysilane.

[0060] In some embodiments, the functional monomer mentioned in the present application may, for example, be one or more of bis(acryloyloxyethyl) disulfide, dimethyl acrylate disulfide, and 2-carboxy-allyl disulfide methacrylic acid.

[0061] In some embodiments, the present application also specifically provides a preparation method of a silicone-acrylate core-shell emulsion as follows:

[0062] 1. Preparation of core layer pre-emulsion: water and emulsifier are added to a pre-emulsification kettle, stirred uniformly (8-12 min), then components (a) and (c) and a chain transfer agent are added, and stirred thoroughly (25-35 min) to obtain a core layer pre-emulsion;

[0063] 2. Core layer pre-emulsion polymerization: water is added to a reaction kettle, heated to 70-80°C, 20-40% of the core layer pre-emulsion and an initiator are added, and seed emulsion polymerization is initiated for 40-50 min; the remaining core layer pre-emulsion is added dropwise to the reaction kettle, and the dropwise addition is completed within 1-2 h at a temperature of 75-80°C, and the reaction is completed (2 h) to obtain a core layer emulsion containing dynamic crosslinking;

[0064] 3. Preparation of shell layer pre-emulsion: water and emulsifier are added to a pre-emulsification kettle, stirred uniformly (8-12 min), then component (b) is added, and stirred thoroughly (25-35 min) to obtain a shell layer pre-emulsion;

[0065] 4. Shell layer coating: In the reactor containing the core layer emulsion, the shell pre-emulsion and initiator are added dropwise. The shell pre-emulsion is added dropwise within 1.5-2.5 hours, and the initiator is added dropwise within 40-50 minutes. The temperature is maintained at 75-85°C, and the reaction is carried out for 2.5-3.5 hours.

[0066] 5. Post-treatment: The temperature of the reaction solution is reduced to 30-40°C, the pH adjusting agent is added dropwise, the reducing agent is added, and the unreacted monomers are removed by filtration after stirring for 3-8 minutes, thereby obtaining the silicone-acrylate core-shell emulsion.

[0067] In the above preparation method, in step 1, the amount of water added is 25-35% of the total weight of components (a) and (c).

[0068] The emulsifier mentioned is a commercially available anionic emulsifier or / and non-ionic emulsifier, such as sodium dodecyl sulfate or / and alkyl phenol polyoxyethylene ether, and the amount of emulsifier added is 2-4% of the total weight of components (a) and (c); the chain transfer agent mentioned is dodecanethiol, and the amount of chain transfer agent added is 1-1.5% of the total weight of components (a) and (c).

[0069] In the above preparation method, in step 2, the initiator is a persulfate initiator, such as ammonium persulfate. The amount of initiator added is 0.1-0.3% of the total weight of components (a) and (c).

[0070] In the above preparation method, in step 3, the amount of water added is 35-55% of the total weight of component (b), and the emulsifier is a commercially available anionic emulsifier or / and non-ionic emulsifier, such as sodium dodecyl sulfate or / and alkyl phenol polyoxyethylene ether, and the amount of emulsifier added is 8-12% of the total weight of component (b).

[0071] In the above preparation method, in step 4, the initiator is a persulfate initiator, such as ammonium persulfate. The amount of initiator added is 0.1-0.3% of the total weight of components (a)-(c).

[0072] In the above preparation method, in step 5, the pH adjusting agent is ammonia water, and the pH of the system is adjusted to 7-8. The reducing agent is ascorbic acid, which promotes dynamic cross-linking of disulfide bonds. The amount of reducing agent added is 0.1-0.2% of the total weight of components (a)-(c).

[0073] The filler mentioned in the present application is selected from solid fillers and porous fillers, wherein the solid filler is selected from one or more of alumina, silica, barium sulfate, or calcium carbonate,

[0074] The porous filler is selected from one or more of diatomite, expanded perlite, porous alumina, or white carbon black.

[0075] The micrometer filler plays a role of physical filling and structural support in the waterproof coating film, and can quickly conduct water vapor, but due to the large particle size of the micrometer filler, there is a risk of liquid water leakage, and the introduction of the sub-micrometer filler can fill in the larger pores, further perfect the network structure and enhance the stability, and prevent water leakage. The nanometer filler has a large specific surface area and numerous small pores, which can provide a large number of adsorption sites and initial diffusion channels for water vapor molecules, and in the waterproof coating film, gas molecules can be transmitted along the network structure.

[0076] The porous filler can provide additional space for water vapor accommodation and migration, and accelerate the diffusion of water vapor. Through the dispersion and support of the micrometer filler, the enhancement of the sub-micrometer filler, the micropores of the nanometer filler, and the internal hollow structure of the porous filler, the air permeability of the coating film is significantly improved under the premise of ensuring the waterproofness of the coating film.

[0077] According to the actual waterproof coating production application needs, the auxiliary agents in the air-permeable waterproof coating composition mentioned in the application include cellulose ether 0.5-1 parts, dispersing agent 2.0-6.0 parts, defoaming agent 3.0-8.0 parts, bactericide 1.0-4.0 parts, mildew-proof agent 1.0-4.0 parts, and thickening agent 0.5-1.5 parts by mass.

[0078] It should be noted that in the specific embodiments of the application, the specific types of auxiliary agents are not specially limited, and related components known in the art that can be applied to waterproof coatings can be reasonably added according to actual production needs.

[0079] The bactericide mentioned in the application includes but is not limited to one or a mixture of several of isothiazolinone (Kathon), 2,2-dibromopropionamide or 1,2-benzisothiazolin-3-one (BIT). The addition of the bactericide can destroy the cell structure of existing microorganisms, and inhibit the growth and reproduction of bacteria, fungi and other microorganisms, thereby preventing the coating from being spoiled, rancid, and sour, etc.

[0080] The mildew-proof agent mentioned in the application includes but is not limited to one or a mixture of several of ROCIMA 342 of Rohm & Haas, p-chloro-m-dimethylphenol or 2-n-octyl-4-isothiazolin-3-one. The mildew-proof agent can prevent the growth and spore germination of mold by inhibiting the enzyme system (such as oxidoreductase, hydrolase) of the mold or interfering with its energy metabolism, thereby preventing the waterproof coating from being mildewed and deteriorated.

[0081] The cellulose ether mentioned in the present application includes but is not limited to one of hydroxyethyl cellulose, methyl hydroxypropyl cellulose ether or hydroxypropyl methyl cellulose ether. The cellulose ether achieves the effect of increasing the viscosity of the coating system by thickening the water phase, ensures that the powder has a suitable consistency during the dispersion process, and avoids the dispersion system being too thin to cause a large number of bubbles. Since the cellulose ether has good thixotropy, it has low viscosity under high shear, high viscosity under static and low shear, and the viscosity is relatively thin during construction, which is easy to construct. After the construction is completed, the viscosity increases rapidly, which effectively prevents sagging.

[0082] The thickening agent mentioned in the present application includes but is not limited to one or a mixture of several of polyurethane thickening agent or polyacrylate thickening agent and the like. The thickening agent interacts with the particles or molecules in the coating to change its spatial structure and flow ability, thereby improving the stability of the waterproof coating, preventing sedimentation, flocculation or delamination, and facilitating construction and storage and transportation.

[0083] The dispersant mentioned in the present application includes but is not limited to one or a mixture of several of polyphosphoric acid sodium salt, polycarboxylic acid sodium salt or polyacrylammonium salt and the like. The dispersant ensures the sufficient dispersion of the filler particles on the one hand, improves the suspension of the filler particles in the liquid, thereby ensuring the stability of the waterproof coating; on the other hand, the dispersant reduces the interfacial tension of the system to enable the filler particles to fully contact the surface of the emulsion particles, thereby ensuring the uniformity of the coating film after construction.

[0084] The defoaming agent mentioned in the present application includes but is not limited to one or a mixture of several of organic silicon or mineral oil. Since bubbles are inevitably generated during the production or construction of the waterproof coating, stress concentration is easily generated around the bubbles, causing fine cracks, which leads to the loss of waterproof effect of the coating film. The defoaming agent has good defoaming and antifoaming properties, can effectively eliminate the bubbles formed in the system, and at the same time inhibit the generation of new bubbles, thereby ensuring the compactness of the coating film.

[0085] In the specific embodiment, the present application also specifically provides a preparation method of the breathable waterproof coating. The main agent, the auxiliary agent and water in the breathable waterproof coating composition are mixed and treated to obtain the breathable waterproof coating.

[0086] Among them, the water mentioned in the present application can use municipal tap water, for example.

[0087] At the same time, in order to further prevent foaming during preparation, and to form a more uniform and stable coating system, the preparation method of the breathable waterproof coating mentioned in the present application preferably comprises the following steps:

[0088] S1. Water is added to the stirred tank, and the cellulose ether is added under stirring and mixed uniformly;

[0089] S2. Add dispersant, defoaming agent, bactericide, mildewcide and 1 / 3~1 / 2 of the silicone-acrylate core-shell emulsion in sequence, and stir uniformly;

[0090] S3. After adding the filler and stirring uniformly, add the remaining silicone-acrylate core-shell emulsion, then add the thickening agent after stirring uniformly, and then discharge to obtain the breathable waterproof coating.

[0091] The stirring speed in the stirring state in S1 can be 450-500 r / min, and the cellulose ether is continuously stirred for 8-12 min after being added.

[0092] The stirring speed in the stirring state in S1 can be 450-500 r / min, and the cellulose ether is continuously stirred for 8-12 min after being added.

[0093] In S3, the filler is dispersed and stirred uniformly at a low speed (500-700 r / min) first, and then stirred at a high speed (900-1100 r / min) for 25-30 min, and then the remaining silicone-acrylate core-shell emulsion is added after the speed is reduced to 750-850 r / min, and the stirring is continued for 8-12 min until the stirring is uniform. The stirring can be continued for 20-30 min after the thickening agent is added to achieve uniform dispersion.

[0094] The stirring speeds mentioned above can all refer to the reasonable speed range in the field, and the stirring time can also be adjusted according to the actual situation, and the uniform dispersion is used as the criterion.

[0095] In the preparation method of the breathable waterproof coating, the cellulose ether is added in water first to achieve a certain thickening effect, so that the powder has a suitable consistency during the dispersion process, and a large number of bubbles are avoided due to the too thin dispersion system. At the same time, the silicone-acrylate core-shell emulsion is added in two times, one part is added together with the dispersant, defoaming agent, bactericide, mildewcide and other components and mixed uniformly, and the other part is added after the filler is added. This process adjustment has two advantages: (1) the process of high-speed dispersion of the powder will produce strong mechanical shear force, and if this strong shear force directly acts on the emulsion particles for a long time, the stability of the emulsion may be damaged, and the risk of emulsion breaking is increased. A part of the emulsion under high shear is appropriately reduced, which can promote the wrapping of the emulsion particles on the powder particles and reduce the risk of emulsion being damaged by mechanical force; (2) the process of high-speed dispersion of the powder will inevitably produce bubbles, and if too much emulsion is added at one time, a large number of bubbles will be generated, which will increase the cost of later defoaming.

[0096] In the specific embodiment, the present application also provides a breathable waterproof coating prepared by the preparation method of the breathable waterproof coating.

[0097] The kinetic diameter of water vapor molecules is about 0.27 nm, and the diameter of the agglomerate of liquid water molecules is greater than 100 nm, and the breathable waterproof coating mentioned in the present application realizes the effect of allowing water vapor molecules to pass through but preventing liquid water from penetrating by compounding multiple functional fillers, constructing a controllable physical pore network, and forming a coating film network with a pore size of 0.3-100 nm.

[0098] In the specific embodiment, the present application also provides an application of the breathable waterproof coating in waterproof and moisture-proof buildings.

[0099] The breathable waterproof coating has a water vapor transmission rate of 148-200 g / (m 2 ·24h), and no liquid water leakage for 2-4h under 1m water column, and simultaneously has good flexibility and adhesion, a breaking elongation of 105-35%, and an adhesion strength of 1.0-1.4 MPa, and can be widely applied to interior wall moisture-proof, exterior wall breathable waterproof, ancient building repair and protection and the like, and has high application value.

[0100] Example 1

[0101] A kind of silicon propylene core-shell emulsion is synthesized by the following method:

[0102] 1, core layer pre-emulsion preparation: 25 parts of water, 2 parts of sodium dodecyl sulfate SDS and 1 part of alkyl phenol polyoxyethylene ether OP-10 are added into a pre-emulsification kettle, stirred for 10 min, then 60 parts of butyl acrylate BA, 20 parts of hydroxyethyl acrylate HEA, 5 parts of dynamic crosslinking agent bis (acryloyloxyethyl) disulfide BADS and 1 part of chain transfer agent dodecanethiol are added, and stirred for 30 min to obtain a core layer pre-emulsion.

[0103] 2, core layer pre-emulsion polymerization: 35 parts of water are added into a reaction kettle, heated to 75℃, and 20% of the core layer pre-emulsion and sodium persulfate aqueous solution (0.2 parts of sodium persulfate and 10 parts of water) are added, and seed emulsion polymerization is initiated for 45 min; the remaining pre-emulsion is added dropwise into the reaction kettle, and the temperature is controlled at 75-80℃ for 1.5h, and the reaction is carried out for 2h to obtain a core layer emulsion containing dynamic crosslinking.

[0104] 3, shell layer pre-emulsion preparation: 10 parts of water, 1 part of sodium dodecyl sulfate SDS and 1 part of alkyl phenol polyoxyethylene ether OP-10 are added into a pre-emulsification kettle, stirred for 10 min, then 12 parts of octamethylcyclotetrasiloxane D4 and 8 parts of gamma-methacryloyloxypropyltrimethoxysilane KH-570 are added, and stirred for 30 min to obtain a shell layer pre-emulsion.

[0105] 4. Shell layer wrapping: In the reactor containing the core layer emulsion, drop the shell pre-emulsion and sodium persulfate aqueous solution (0.3 parts of sodium persulfate and 10 parts of water), the shell pre-emulsion is dropped within 2h, the sodium persulfate aqueous solution is dropped within 45min, the temperature is maintained at 80℃, and the reaction is carried out for 3h;

[0106] 5. Post-treatment: The temperature of the reaction solution is reduced to 35℃, ammonia water is added to adjust the pH to 7-8, 0.1 parts of reducing agent ascorbic acid is added, stirred for 5min, and then filtered to remove unreacted monomers, to obtain the silicone-acrylate core-shell emulsion I.

[0107] The solid content of the silicone-acrylate core-shell emulsion I is (49-52)%, the silicon content is (5-8)%, and the particle size is (80-100)nm. (The monomer content varies within the scope of the present application, and the above parameters have no significant effect, and the conventional detection is represented as a certain range interval)

[0108] The solid content can be obtained by measuring the non-volatile matter, and the test method can refer to GB / T 20623-2006;

[0109] The silicon content can be tested by X-ray fluorescence spectroscopy, and the test method can refer to ISO 3497:2000;

[0110] The particle size can be tested by dynamic light scattering, and the test method can refer to ISO 22412:2017.

[0111] The present embodiment also provides a composition for breathable waterproof coating, which comprises a main agent and an auxiliary agent, wherein the main agent comprises the following components in mass parts: 320 parts of silicone-acrylate core-shell emulsion, 475 parts of filler,

[0112] The auxiliary agent comprises 0.5 parts of cellulose ether, 3.0 parts of dispersant, 4.0 parts of defoaming agent, 2.0 parts of bactericide, 3.0 parts of mildewcide, and 1.0 parts of thickening agent.

[0113] The present embodiment also provides a breathable waterproof coating, which is prepared by the following steps:

[0114] S1. Put 191.5 parts of water into the stirred tank, start stirring, the speed is 450-500r / min, add 0.5 parts of cellulose ether HEC into the stirred tank, continue stirring for 10min;

[0115] S2. Add 3 parts of dispersant W-58, 4 parts of defoaming agent DF-520, 2 parts of bactericide Kason, 3 parts of mildewcide, and 1 / 2 silicone-acrylate core-shell emulsion (160 parts) in sequence, and stir for 10min;

[0116] S3. Add 5 parts of fumed silica N-20ST (D50=20nm), 141 parts of γ-Al2O3 (D50=250nm), 235 parts of α-Al2O3 (D50=5μm), 94 parts of α-Al2O3 (D50=42μm) in turn, uniformly dispersed at low speed (600r / min) first, then stirred at high speed (1000r / min) for 25-30min, adjust the speed to 800r / min, put the remaining 1 / 2 of the silicone-acrylate core-shell emulsion (160 parts) into the stirring kettle, stir for 10min, slowly add 1 part of thickening agent U505, continue to stir for 30min;

[0117] Discharge and package, and a waterproof coating is obtained.

[0118] Example 2

[0119] A silicone-acrylate core-shell emulsion is synthesized by the following method:

[0120] The preparation steps of Example 1 are repeated, except that the functional monomer BADS is adjusted to 3 parts, to prepare a silicone-acrylate core-shell emulsion II, and the rest of the components and their added amounts remain unchanged.

[0121] The silicone-acrylate core-shell emulsion II has a solid content of (49-52)%, a silicon content of (5-8)%, and a particle size of (80-100)nm.

[0122] This example also provides a breathable waterproof coating composition, which is the same as Example 1, except that the silicone-acrylate core-shell emulsion is the silicone-acrylate core-shell emulsion II.

[0123] This example also provides a breathable waterproof coating, which is prepared by the steps of Example 1.

[0124] Example 3

[0125] A silicone-acrylate core-shell emulsion is synthesized by the following method:

[0126] The preparation steps of Example 1 are repeated, except that the functional monomer BADS is adjusted to 8 parts, to prepare a silicone-acrylate core-shell emulsion III, and the rest of the components and their added amounts remain unchanged.

[0127] The silicone-acrylate core-shell emulsion III has a solid content of (49-52)%, a silicon content of (5-8)%, and a particle size of (80-100)nm.

[0128] This example also provides a breathable waterproof coating composition, which is the same as Example 1, except that the silicone-acrylate core-shell emulsion is the silicone-acrylate core-shell emulsion III.

[0129] This example also provides a breathable waterproof coating, which is prepared by the steps of Example 1.

[0130] Example 4

[0131] A silicone-acrylate core-shell emulsion was synthesized by the following method:

[0132] The preparation procedure of Example 1 was repeated, except that the silicone shell monomer D4 was adjusted to 8 parts and KH-570 was adjusted to 12 parts, to prepare a silicone-acrylate core-shell emulsion IV, with the rest of the components and their added amounts remaining unchanged.

[0133] The silicone-acrylate core-shell emulsion IV had a solid content of (49-52)%, a silicon content of (5-8)%, and a particle size of (80-100) nm.

[0134] This example also provides a composition for a breathable waterproof coating, which is the same as Example 1, except that the silicone-acrylate core-shell emulsion is the silicone-acrylate core-shell emulsion IV.

[0135] This example also provides a breathable waterproof coating, which is prepared by the same procedure as Example 1.

[0136] Example 5

[0137] A silicone-acrylate core-shell emulsion was synthesized by the following method:

[0138] The preparation procedure of Example 1 was repeated, except that the silicone shell monomer D4 was adjusted to 16 parts and KH-570 was adjusted to 4 parts, to prepare a silicone-acrylate core-shell emulsion V, with the rest of the components and their added amounts remaining unchanged.

[0139] The silicone-acrylate core-shell emulsion V had a solid content of (49-52)%, a silicon content of (5-8)%, and a particle size of (80-100) nm.

[0140] This example also provides a composition for a breathable waterproof coating, which is the same as Example 1, except that the silicone-acrylate core-shell emulsion is the silicone-acrylate core-shell emulsion V.

[0141] This example also provides a breathable waterproof coating, which is prepared by the same procedure as Example 1.

[0142] Example 6

[0143] This example provides a composition for a breathable waterproof coating, which is the same as Example 1, except that the γ-Al2O3 (D50=250 nm) was adjusted to 188 parts and the α-Al2O3 (D50=5 μm) was adjusted to 188 parts.

[0144] This example also provides a breathable waterproof coating, which is prepared by the same procedure as Example 1.

[0145] Example 7

[0146] A silicone-acrylate core-shell emulsion was synthesized by the following method:

[0147] The preparation step of Example 1 was repeated, except that no functional monomer BADS was added, to prepare a silicone-acrylate core-shell emulsion VI, with the rest of the components and their added amounts remaining unchanged.

[0148] The silicone-acrylate core-shell emulsion VI had a solid content of (49-52) %, a silicon content of (5-8) %, and a particle size of (80-100) nm.

[0149] This example also provides a composition for a breathable waterproof coating, which is the same as Example 1, except that the silicone-acrylate core-shell emulsion is the silicone-acrylate core-shell emulsion VI.

[0150] This example also provides a breathable waterproof coating, which is prepared by the same steps as Example 1.

[0151] Example 8

[0152] This example provides a composition for a breathable waterproof coating, which is the same as Example 1, except that the silicone-acrylate core-shell emulsion is adjusted to 350 parts, and the water is adjusted to 161.5 parts, with the rest of the components and their added amounts remaining unchanged.

[0153] This example also provides a breathable waterproof coating, which is prepared by the same steps as Example 1.

[0154] Example 9

[0155] This example provides a composition for a breathable waterproof coating, which is the same as Example 1, except that the silicone-acrylate core-shell emulsion is adjusted to 290 parts, and the water is adjusted to 221.5 parts, with the rest of the components and their added amounts remaining unchanged.

[0156] This example also provides a breathable waterproof coating, which is prepared by the same steps as Example 1.

[0157] Comparative Example 1

[0158] This example provides a composition for a breathable waterproof coating, which is the same as Example 1, except that the filler is a single particle size filler α-Al2O3 (D50=42 μm) in the same amount.

[0159] This example also provides a breathable waterproof coating, which is prepared by the same steps as Example 1.

[0160] Comparative Example 2

[0161] This comparative example provides a breathable waterproof coating, which is prepared by the same steps as Example 1. The difference is that the silicone-acrylate core-shell emulsion is replaced by a general-purpose acrylic emulsion, BLJ-5619, Shanghai Baolijia Chemical Co., Ltd.

[0162] Comparative Example 3

[0163] This comparative example provides a composition for a breathable waterproof coating, which is the same as Example 1, except that the α-Al2O3 (D50 = 42 μm) is replaced by α-Al2O3 (D50 = 60 μm), and the rest of the components and their added amounts remain unchanged.

[0164] This comparative example also provides a breathable waterproof coating, which is prepared by the same steps as Example 1.

[0165] Results detection

[0166] The performance test method is as follows:

[0167] (1) The water vapor transmission rate is tested according to 9.2.4 in GB / T1037-2021. The test is carried out by weight loss method, temperature (23.0±0.5) ℃, relative humidity (90±2) %, dry film thickness (1.0±0.1) mm;

[0168] (2) The water impermeability is tested according to method A in GB / T328.10-2007;

[0169] (3) The tensile strength and elongation at break are tested according to 9.2.1 in GB / T16777-2008, and the test speed is 200 mm / min;

[0170] (4) The adhesion strength is tested according to 7.6 in GB / T23445-2009.

[0171] The test results are shown in Table 1:

[0172] Table 1.

[0173] No. Water vapour transmission g / (m 2 ·24h) Water impermeability Tensile strength MPa Elongation at break % Adhesion strength MPa Example 1 187 1 m water column for 4 h, no leakage 1.3 123 1.2 Example 2 173 1 m water column for 4 h, no leakage 1.3 135 1.1 Example 3 180 1 m water column for 4 h, no leakage 1.4 117 1.3 Example 4 164 1 m water column for 2 h, no leakage 1.4 108 1.4 Example 5 156 1 m water column for 4 h, no leakage 1.2 130 1.2 Example 6 193 1 m water column for 4 h, no leakage 1.1 120 1.0 Example 7 162 1 m water column for 4 h, no leakage 1.2 125 1.2 Example 8 148 1 m water column for 4 h, no leakage 1.3 130 1.3 Example 9 200 1 m water column for 2 h, no leakage 1.2 105 1.1 Comparative Example 1 413 1 m water column for 2 h, leakage 0.4 52 0.5 Comparative Example 2 120 1 m water column for 4 h, no leakage 1.4 115 1.3 Comparative Example 3 195 1 m water column for 2 h, leakage 1.1 119 1.1

[0174] From the test results of Table 1 above:

[0175] (1) Comparing Example 2-3 with Example 1, the disulfide bond in BADS can form dynamic crosslinking points, which will break in a high humidity environment, increasing the porosity and thus improving the air permeability. However, with the increase of BADS content, the network structure is densified due to excessive crosslinking, the porosity decreases, the air permeability decreases, and the flexibility of the coating film also decreases.

[0176] (2) Example 4-5 compared with Example 1, D4 and KH-570 as the shell layer of the silicone monomer, D4 monomer forms polysiloxane chain (Si-O-Si) by ring-opening polymerization, providing a low surface energy hydrophobic layer to block liquid water, while there is enough intermolecular gap between Si-O-Si chains to allow gas to pass through; KH-570 monomer contains double bonds and methoxy groups, the double bonds can participate in acrylate copolymerization, and the methoxy groups can condense with Si-OH after hydrolysis, thereby enhancing the interfacial bonding of silicone and acrylic acid and reducing phase separation. If the ratio of D4 / KH-570 is too low, both the air permeability and the water resistance will decrease, and if the ratio of D4 / KH-570 is too high, the air permeability will also decrease due to the strong hydrophobicity of D4 hindering the diffusion of water vapor. A moderate ratio of D4 / KH-570 gives the coating film air permeability and water resistance.

[0177] (3) Example 6 compared with Example 1, when the ratio of γ-Al2O3 (D50=250nm): α-Al2O3 (D50=5μm): α-Al2O3 (D50=42μm) changes from 3:5:2 to 4:4:2, i.e. the content of sub-micron porous alumina increases and the content of micron alumina decreases, the sub-micron porous alumina provides larger porosity in the coating, and the internal structure of the particles is hollow, further accelerating the diffusion of water vapor, increasing the air permeability of the coating film, but the decrease of α-Al2O3 (D50=42μm) will weaken the strength of the coating film, such as the tensile strength decreasing to 1.1MPa and the adhesive strength decreasing to 1.0MPa.

[0178] (4) Example 7 does not add functional monomers, and the absence of functional monomers will slightly reduce the air permeability of the coating film, but has no obvious effect on other properties.

[0179] (5) Example 8-9 compared with Example 1, emulsion as the key film-forming material, when the content of emulsion increases, the compactness of the coating film increases, and its water resistance also increases, but with further increase of the content of emulsion, the compactness of the coating film is too strong, which will reduce the air permeability. Scientific compounding of emulsion and fillers can precisely control the water resistance and air permeability.

[0180] Comparative Example 1 is a coating prepared from a single particle size and large particle size (D50=42μm) α-Al2O3, the coating film after film formation has a very obvious particle feel and many defects, almost no water resistance, and the mechanical properties are also greatly reduced.

[0181] Comparative Example 2 is a coating prepared from a commercially available acrylic emulsion, and its air permeability is significantly reduced.

[0182] Comparative Example 3 uses micron α-Al2O3 (D50=60μm) with a larger particle size, and the sub-micron and nano fillers are not enough to fill in the pores, resulting in water leakage.

[0183] It should be pointed out finally that the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit the same; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that the technical solutions recorded in the foregoing embodiments can still be modified, or some technical features therein can be replaced equivalently; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A composition for a breathable waterproof paint, characterized by, The composition comprises a main agent and an auxiliary agent, the main agent includes the following components in mass parts: silicone propylene core-shell emulsion 290-350 parts, filler 400-500 parts; The silicone propylene core-shell emulsion is prepared by core-shell emulsion polymerization reaction of core layer monomers containing acrylic acid and shell layer monomers containing silicone, the acrylic acid core layer monomers are acrylic acid monomers containing -OH and -COOH groups, and the shell layer monomers containing silicone are silicone monomers having a Si-O-Si main chain; The filler is a complex filler composed of micron, submicron and nanoscale fillers, and the filler particle size D50 is 200 nm-50 μm; The core layer monomers in the raw material components of the silicone propylene core-shell emulsion further comprise functional monomers, the functional monomers are disulfide bond-containing monomers, the content of the acrylic acid core layer monomers is 70-80 wt%, the content of the shell layer monomers containing silicone is 15-25 wt%, and the content of the functional monomers is 2-8 wt%; The silicone content of the silicone propylene core-shell emulsion is 5-10%, and the particle size is 50-150 nm.

2. The composition for a breathable waterproof paint according to claim 1, wherein The acrylic acid core layer monomers are selected from one or more of butyl acrylate, acrylic acid and hydroxyhexyl acrylate; And / or, the shell layer monomers containing silicone are selected from one or more of octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, gamma-methacryloyloxytrimethoxysilane and gamma-aminopropyltriethoxysilane; And / or, the functional monomers are selected from one or more of bis(acryloyloxyethyl) disulfide, dimethyl acrylate disulfide and 2-carboxy-allyl disulfide methyl acrylate.

3. The composition for a breathable waterproof paint according to claim 1 or 2, wherein The filler includes solid fillers and porous fillers.

4. The composition for a breathable waterproof paint according to claim 3, wherein The solid fillers are selected from one or more of alumina, silica, barium sulfate or calcium carbonate; And / or, the porous fillers are selected from one or more of diatomite, expanded perlite, porous alumina or white carbon black.

5. The composition for a breathable waterproof paint according to claim 1 or 2, wherein The auxiliary agent includes cellulose ether 0.5-1 part, dispersant 2.0-6.0 parts, defoaming agent 3.0-8.0 parts, bactericide 1.0-4.0 parts, mildew-proof agent 1.0-4.0 parts and thickening agent 0.5-1.5 parts in mass parts.

6. A method for producing a breathable waterproof paint based on the breathable waterproof paint composition according to any one of claims 1 to 5, characterized by, The method comprises the following steps: S1. Water is added to a stirred tank, and cellulose ether is added under stirring to mix uniformly; S2. Dispersant, defoaming agent, bactericide, mildew-proof agent and 1 / 3-1 / 2 of the silicone propylene core-shell emulsion are sequentially added and stirred uniformly; S3. The filler is added and stirred uniformly, then the remaining silicone propylene core-shell emulsion is added, the thickening agent is added after stirring uniformly, and the breathable waterproof coating is obtained after discharging.

7. A breathable waterproof coating prepared by the preparation method of the breathable waterproof coating of claim 6.

8. Application of the breathable waterproof coating of claim 7 in waterproof and moisture-proof buildings.