Composite saltpetering-resistant agent, saltpetering-resistant and yellowing-resistant colored facing mortar and preparation method of composite saltpetering-resistant and yellowing-resistant colored facing mortar

Abstract

The invention relates to the technical field of building materials, in particular to a composite saltpetering-resistant agent, saltpetering-resistant and yellowing-resistant colored facing mortar and a preparation method thereof.The composite saltpetering-resistant agent comprises a cation adsorption phase, a light stabilization phase and a hydrophobic phase; the cation adsorption phase is of a porous skeleton structure and comprises zeolite activated by acid and modified by organic functional groups; the light stable phase is a core-shell structure nano-composite and comprises a metal oxide core and a silicon dioxide shell; silanol groups of the hydrophobic phase are covalently bonded with hydroxyl groups on the surfaces of the cationic adsorption phase and the light stable phase. According to the technical scheme provided by the invention, the core problems of saltpetering, yellowing and insufficient durability of traditional facing mortar are synergistically solved by constructing a triple protection mechanism of chemical adsorption, physical barrier and light stability, the key indexes such as the saltpetering-resistant qualification rate, the weather resistance grade and the strength retention rate of the facing mortar can be improved, and the facing mortar has the advantages of high strength, high durability and the like. Furthermore, the decoration effect durability and the engineering applicability of the colored facing mortar are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of building materials, in particular to a composite anti-efflorescence agent, anti-efflorescence and yellowing-resistant colored finishing mortar and a preparation method thereof. BACKGROUND

[0002] Finishing mortar is an environmentally friendly material widely used in the decoration of building exterior walls, with the advantages of rich colors, diverse textures, and convenient construction. However, traditional cement-based finishing mortar has the following shortcomings. First, the soluble alkali (such as calcium hydroxide) in the mortar migrates to the surface with water, reacts with carbon dioxide in the air to form white calcium carbonate crystals (i.e., "white frost"), causing color contamination, color difference, and deterioration of the decorative effect, which seriously affects the aesthetics. Especially in high humidity (RH>80%) or low temperature (<15℃) environments, the risk of efflorescence increases significantly. The hydrophobic agent used in the prior art can only delay the intrusion of water, but cannot fundamentally eliminate the internal alkali source. Special cement can reduce the alkalinity of the system, but the cost is too high to be widely applied. Second, in light and hot environments, the organic pigments or cementitious materials in the mortar are prone to oxidative degradation. The pigment undergoes molecular chain rupture under ultraviolet radiation or oxidation, resulting in color fading, yellowing, and deterioration of the durability of the decorative effect. Although the addition of polymer emulsion can enhance the density of the mortar, the polymer emulsion is prone to aging and yellowing under ultraviolet radiation, and may react with some pigments, affecting the surface effect. SUMMARY

[0003] One of the purposes of the present application is to provide a composite anti-efflorescence agent to avoid the shortcomings of the prior art. By constructing a triple protection mechanism of chemical adsorption, physical barrier, and light stability, the core problems of traditional finishing mortar, such as efflorescence, yellowing, and insufficient durability, are solved. The key indicators such as anti-efflorescence pass rate, weather resistance grade, and strength retention rate of the finishing mortar are improved, thereby enhancing the durability of the decorative effect and the engineering applicability of the colored finishing mortar.

[0004] The second purpose of the present application is to provide a preparation method of the composite anti-efflorescence agent.

[0005] The third purpose of the present application is to provide an anti-efflorescence and yellowing-resistant colored finishing mortar.

[0006] The fourth purpose of the present application is to provide a preparation method of the anti-efflorescence and yellowing-resistant colored finishing mortar.

[0007] One of the purposes of the present application is achieved by the following technical solutions: A composite anti-efflorescence agent is provided, which includes a cation adsorption phase, a light stabilization phase, and a hydrophobic phase. The cation adsorption phase is a porous framework structure containing zeolite modified by acid activation and organic functional groups. The acid activation and organic functional group modification are sequential process steps. The light-stable phase is a core-shell nano-composite, which is loaded on the surface and in the pores of the cation-adsorbing phase by physical adsorption or chemical bonding, and comprises a metal oxide inner core and a silica shell, wherein the metal oxide inner core is a metal oxide capable of absorbing ultraviolet light; The hydrophobic phase is a three-dimensional cross-linked network formed by hydrolysis and condensation of silane compounds, and the silanol groups of the three-dimensional cross-linked network are covalently bonded to the hydroxyl groups on the surface of the cation-adsorbing phase and the light-stable phase.

[0008] In some embodiments, the mass ratio of the cation-adsorbing phase, the light-stable phase and the hydrophobic phase is (8-12):1:(16-24); The zeolite is at least one selected from sodium zeolite, clinoptilolite, mordenite and synthetic zeolite, and the pore size of the zeolite is 30-100 nm and the specific surface area is 300-800 m 2 / g after acid activation; The acid activation treatment of the zeolite uses a hydrochloric acid or nitric acid solution; The organic functional group modification uses a silane coupling agent, and the silane coupling agent is γ-aminopropyl triethoxysilane, γ-glycidyl ether propyl trimethoxysilane or 3-mercaptopropyl trimethoxysilane.

[0009] In some embodiments, the metal oxide inner core is anatase TiO2, hexagonal ZnO or cubic CeO2, and the average particle size is 5-20 nm; The average thickness of the silica shell is 2-5 nm; The silane compound includes at least one of methyl trimethoxysilane, ethyl triethoxysilane and vinyl trimethoxysilane.

[0010] Compared with the prior art, the composite anti-flooding agent provided in the application builds a comprehensive anti-flooding protection system through the triple synergistic effect of the cation-adsorbing phase, the light-stable phase and the hydrophobic phase. Firstly, the zeolite activated by acid and modified by an organic functional group captures free Ca 2+ in the mortar through the porous framework structure and the -NH2 groups on the surface in the form of coordination bonds, which significantly improves the capture of free Ca 2+The saturated adsorption amount of the cation adsorption phase is increased, and the technical purpose of reducing the migration of alkali ions from the source is achieved. Secondly, the three-dimensional cross-linked network formed by the hydrolysis and condensation of the silane compound is covalently combined with the surface hydroxyl groups of the cation adsorption phase and the light stabilization phase, forming a continuous hydrophobic film inside the mortar, which significantly reduces the water absorption of the finishing mortar and effectively blocks the channel of water carrying alkali salt to the surface. Thirdly, the metal oxide as the core absorbs ultraviolet light, and the SiO2 as the shell layer can avoid the side effects of photocatalysis. Under the action of the core-shell structure, not only the weather resistance is improved, but also the SiO2 can react with Ca(OH)2 to generate C-S-H gel, which further consumes the alkali source.

[0011] The second purpose of the present application is achieved by the following technical scheme: The application provides a preparation method of a composite anti-alkali agent, which comprises the following steps: Zeolite is crushed and passed through a 200-mesh sieve, and then 10-20% hydrochloric acid solution is added at a solid-liquid ratio of 1:4, and stirred at 70-90 DEG C for 1-3h, and then filtered and washed until neutral, and then dried at 120 DEG C; the dried product is added into an ethanol solution containing a silane coupling agent, and refluxed at 60-70 DEG C for 3-5h, and then filtered, washed with ethanol for 3 times, and then vacuum dried to obtain a cation adsorption phase; Nanometer metal oxide particles are dispersed in ethanol, and ultrasonic treatment is carried out for 30 min to obtain a dispersion liquid; an ethyl silicate and ethanol mixed solution with a volume ratio of 1:4 is added dropwise into the dispersion liquid, ammonia water is used to adjust the pH of the system to 8-10, and stirring is carried out at 50-60 DEG C for 2-4h, and then centrifugal separation is carried out after aging for 24h, and then ethanol washing and drying at 60 DEG C are carried out to obtain a light stabilization phase; The cation adsorption phase and the light stabilization phase are added into deionized water, and stirring adsorption is carried out at 60-70 DEG C for 4-6h, and then filtered and dried, and then a silane compound is added, and stirring reaction is carried out at 80-90 DEG C for 2-4h, and then filtered and dried, and then crushed and passed through a 200-mesh sieve to obtain a composite anti-alkali agent.

[0012] In some embodiments, the concentration of the silane coupling agent in the ethanol solution containing the silane coupling agent is 5-8%; The dropwise adding speed of the ethyl silicate and ethanol mixed solution is 0.5-1.0 mL / min.

[0013] In some embodiments, when the metal oxide is TiO2, the step of dispersing the nanometer metal oxide particles in ethanol is replaced by adding butyl titanate into ethanol, adding 0.001 mol / L nitric acid dropwise to adjust the pH to 3-4, and hydrolyzing to obtain a TiO2 sol; the volume ratio of the butyl titanate to ethanol is 1: (4-6).

[0014] Compared with the prior art, the preparation method of the composite anti-alkali agent provided by the application has the following beneficial effects: (1) The step-by-step treatment of the zeolite of the application through acid activation and organic modification ensures that the zeolite can be expanded while the surface of the zeolite can also be grafted with sufficient organic functional groups (such as -NH2), thereby improving the adsorption selectivity of the zeolite to free Ca 2+ .

[0015] (2) The present application can control the particle size of the core-shell structure by the gel method combined with dropwise addition of a mixture of ethyl silicate / ethanol, thereby avoiding agglomeration of the nanoparticles.

[0016] (3) The cation adsorption phase and the light stabilization phase of the application are first stirred and adsorbed at 60-70°C for 4-6h, which can ensure uniform loading, and then a silane compound is added and reacted at 80-90°C for 2-4h, which can ensure that the hydrophobic network is fully crosslinked.

[0017] (4) The present application uses recyclable ethanol as a solvent, which is suitable for large-scale production.

[0018] The third object of the application is achieved by the following technical scheme: Provided is an anti-alkali and yellowing-resistant colored finishing mortar, which comprises Portland cement, metakaolin, white carbon black, graded quartz sand, pigment, sodium hexametaphosphate, polymer latex powder, wood fiber, expanding agent, ultraviolet absorber, cellulose ether, and the composite anti-alkali agent as described above, or the composite anti-alkali agent prepared by the preparation method as described above.

[0019] In some embodiments, the addition amount of each component is as follows in terms of weight percentage: Portland cement 20-35wt%; Metakaolin 3-8wt%; White carbon black 1-3wt%; Graded quartz sand 50-70wt%; Pigment 0.5-3wt%; Sodium hexametaphosphate 0.05-0.3wt%; Polymer latex powder 2-6wt%; Wood fiber 0.2-0.8wt%; Expanding agent 0.5-3wt%; Ultraviolet absorber 0.2-0.5wt%; Cellulose ether 0.15-0.3wt%; Composite anti-alkali agent 0.5-3wt%.

[0020] In some embodiments, the specific surface area of the metakaolin is ≥500m 2 / kg. The specific surface area of the white carbon black is greater than or equal to 500 m 2 / kg, and the silica content is greater than or equal to 95%; The ultraviolet absorber is a benzotriazole compound, and the purity is greater than or equal to 99%; The cellulose ether is a hydroxyethyl methyl cellulose ether, and the Brookfield viscosity is 10,000-15,000 cP; The polymer latex powder is a hydrophobic type vinyl acetate-vinyl ester-ethylene terpolymer, and the bulk density is 400-550 kg / m 3 , and the minimum film forming temperature is 0 DEG C; The length of the wood fiber is 0.5-3 mm, and the bulk density is 20-60 g / L; The expanding agent is a calcium aluminate system expanding agent; The purity of the sodium hexametaphosphate is greater than or equal to 65%, the phosphorus pentoxide content is greater than or equal to 68% in terms of oxides, and the water insoluble matter is less than or equal to 0.1%.

[0021] Compared with the prior art, the anti-alkali bleeding and yellowing color finishing mortar provided by the application has the following beneficial effects: (1) The portland cement of the application is matched with metakaolin and white carbon black, the compactness is improved through micro aggregate filling and pozzolanic reaction, the porosity is reduced, and the bending strength and compressive strength are improved.

[0022] (2) The sodium hexametaphosphate disperses pigments and fillers, and at the same time, the sodium hexametaphosphate can also complex Ca 2+ ; in combination with the polymer latex powder, a flexible film is formed, and the tensile bonding strength of the color finishing mortar can be improved.

[0023] (3) The composite anti-alkali bleeding agent and the ultraviolet absorber are synergistic, the composite anti-alkali bleeding agent blocks the alkali bleeding path, and the ultraviolet absorber shields ultraviolet rays, which can significantly improve the aging resistance of the color finishing mortar and improve the application effect.

[0024] The fourth purpose of the application is achieved by the following technical scheme: Provided is a preparation method of an anti-alkali bleeding and yellowing color finishing mortar, including the following steps: The composite anti-alkali bleeding agent and 30% of the total amount of the formula graded quartz sand are added to a hot air activation bin, and pre-mixed under the condition of 50 DEG C stirring, to obtain a first dispersion; The ultraviolet absorber and white carbon black are mixed in a mass ratio of 1:(3-5), added to an ultrasonic dispersing machine, and treated with ultrasonic waves in deionized water as a dispersion medium, and then spray dried to obtain a second dispersion; The polymer emulsion powder and pigment are added into a horizontal screw ribbon mixer for dry mixing; the first dispersion, the second dispersion and sodium hexametaphosphate are added for dry mixing; and the metakaolin, Portland cement, the remaining 70% of the graded quartz sand and the cellulose ether are added for dry mixing to prepare the alkali bleeding and yellowing resistant colored finishing mortar.

[0025] Compared with the prior art, the method for preparing the alkali bleeding and yellowing resistant colored finishing mortar has the following beneficial effects: (1) The composite alkali bleeding agent and 30% of the graded quartz sand are premixed in a 50℃ hot air activation bin for 5 minutes, so that the hydrophobic components uniformly coat the surface of the sand particles to form a capillary pore blocking layer, and the alkali bleeding resistance of the colored finishing mortar is improved.

[0026] (2) The ultraviolet absorber is mixed with the white carbon black and then ultrasonically treated, so that the ultraviolet absorber is adsorbed by the white carbon black with a high specific surface area, and the agglomeration of the ultraviolet absorber in the mortar is avoided, thereby improving the ultraviolet shielding efficiency of the mortar.

[0027] (3) The polymer emulsion powder and the pigment are dry mixed first, then the premixed alkali bleeding agent, ultraviolet absorber and sodium hexametaphosphate are added, and finally the cementing materials and the remaining sand are added, and the mortar is uniformly mixed in batches to ensure the dispersion of the mortar, thereby improving the durability and economy of the exterior wall decoration, and having a high engineering promotion value. DETAILED DESCRIPTION

[0028] In the prior art, cement-based colored finishing mortar has long been plagued by alkali bleeding and yellowing. Alkali bleeding is caused by the migration of internal soluble alkali to the surface to form white crystals, which destroys the appearance of the decorative layer; yellowing is caused by the degradation of organic materials under ultraviolet light or oxidation. Traditional solutions have limitations, such as hydrophobic agents that only delay water penetration and cannot eliminate alkali sources, and polymer emulsions that are prone to aging and have poor compatibility with pigments. These problems are particularly prominent in high-temperature and high-humidity environments or strong ultraviolet light, which seriously affects the durability and decorative effect of the finishing mortar.

[0029] To solve the above problems, the embodiments of the present application provide a composite alkali bleeding agent, an alkali bleeding and yellowing resistant colored finishing mortar and a preparation method thereof. By constructing a triple protection mechanism of chemical adsorption, physical barrier and light stability, the core problems of traditional finishing mortar, such as alkali bleeding, yellowing and insufficient durability, are solved, and the key indicators of the finishing mortar, such as alkali bleeding qualification rate, weather resistance grade and strength retention rate, are improved, thereby improving the durability and engineering applicability of the colored finishing mortar.

[0030] The application provides a composite anti-alkali bleeding agent, which comprises a cation adsorption phase, a light stability phase and a hydrophobic phase. The cation adsorption phase is a porous framework structure and comprises zeolite modified by acid activation and organic functional groups, wherein the acid activation and the organic functional group modification are sequential process steps. The light stability phase is a core-shell structure nanocomposite, which is loaded on the surface and pores of the cation adsorption phase through physical adsorption or chemical bonding, and comprises a metal oxide core and a silica shell, wherein the metal oxide core is a metal oxide capable of absorbing ultraviolet light. The hydrophobic phase is a three-dimensional cross-linked network formed by hydrolysis and condensation of silane compounds, and the silanol groups thereof are covalently bonded to the hydroxyl groups on the surfaces of the cation adsorption phase and the light stability phase.

[0031] In the embodiment, the cation adsorption phase is a modified material for expanding the pore structure of zeolite by acid etching and introducing organic functional groups. The acid activation can increase the specific surface area and pore diameter of the zeolite, thereby increasing the ion exchange capacity of the zeolite. The introduced organic functional groups, such as (-NH2), can enhance the adsorption selectivity of calcium ions. The light stability is provided by the nanoparticles composed of a metal oxide core and a silica shell. The core absorbs ultraviolet energy, and the shell prevents the destruction of organic components by photocatalytic reaction. The hydrophobic phase is a continuous network structure formed by hydrolysis and condensation of silane, which is chemically bonded to cover the surfaces of the adsorption phase and the stability phase, thereby blocking the water penetration path. The zeolite is activated by acid to form developed pore channels, and free calcium ions are captured by ion exchange. The light stability phase with a core-shell structure is uniformly distributed inside and outside the pores. The metal oxide core absorbs ultraviolet light, and the silica shell isolates the photocatalytic activity. The silane compound forms a dense hydrophobic layer on the surface of the material, thereby preventing the outward migration of water carrying alkali salt. The cation adsorption phase, the light stability phase and the hydrophobic phase form a stable composite structure through chemical bonding. The cation adsorption phase inhibits the precipitation of alkali source, the light stability phase protects the organic components, and the hydrophobic phase blocks the migration channel, thereby solving the problems of alkali bleeding and yellowing.

[0032] The conventional anti-alkali agent often has performance defects due to an unbalanced proportion of various functional components. For example, if the cation adsorption phase is insufficient, free calcium ions cannot be effectively captured, and the source of alkali cannot be blocked. If the light stabilization phase is excessive, it is easy to agglomerate and cause color difference, and the cost is difficult to control. If the hydrophobic phase is insufficient, a continuous barrier network cannot be formed, and the migration of alkali salt is caused by water penetration. Therefore, in order to realize the synergistic effect of the cation adsorption phase, the light stabilization phase and the hydrophobic phase, and solve the technical problems of alkali, yellowing and insufficient durability, on the basis of the above specific embodiments, the mass ratio of the cation adsorption phase, the light stabilization phase and the hydrophobic phase is (8-12):1:(16-24). In some embodiments, the mass ratio of the cation adsorption phase to the light stabilization phase can be 8:1 or 9:1 or 10:1 or 11:1. Controlling the mass ratio of the cation adsorption phase to the light stabilization phase in the range of 8-12:1, for example, 8:1, can ensure that the light stabilization phase is fully loaded in the pores of the adsorption phase, avoiding excessive light stabilization phase blocking the pores and affecting the adsorption efficiency. In some specific embodiments, the amount of silane compound added is 1 to 2 times the amount of cation adsorption phase. This amount can form a continuous hydrophobic layer on the surface of the adsorption phase, while avoiding excessive cross-linking that increases the brittleness of the material. In addition, this mass ratio also takes into account the cost factor, improving the market competitiveness of the product.

[0033] Further, the zeolite is selected from at least one of sodium zeolite, clinoptilolite, mordenite and synthetic zeolite, and the pore size of the zeolite after acid activation is 30-100 nm, and the specific surface area is 300-800 m 2 / g. In some embodiments, the acid can be hydrochloric acid or nitric acid, and the concentration can be 10-20%. Hydrogen ions are used to dissolve the surface layer and the pore surface layer of the zeolite. The pore size range of the acid-activated zeolite is positively correlated with the acid activation time, the type of acid and the concentration of acid. Those skilled in the art can freely select the type of acid, the concentration of acid and the acid activation time according to the required pore size.

[0034] Further, the organic functional group modification uses a silane coupling agent, which is γ-aminopropyl triethoxysilane, γ-glycidyl ether propyl trimethoxysilane or 3-mercaptopropyl trimethoxysilane. The amino group or mercapto group thereof reacts with the hydroxyl group on the surface of the zeolite to form a stable chemical bond, enhancing the organic-inorganic interface bonding force.

[0035] Further, the metal oxide core is anatase TiO2, hexagonal ZnO or cubic CeO2, and the average particle size is 5-20 nm.

[0036] Specifically, the metal oxide inner core in the application is anatase TiO2, hexagonal ZnO or cubic CeO2, and the specific crystal structure realizes the function of ultraviolet light absorption, and the crystal structure has higher light stability and ultraviolet absorption efficiency, and forms a strong absorption band in the ultraviolet light band to block the destructive effect of ultraviolet rays on organic pigments and polymer latex powder.

[0037] Further, the average thickness of the silica shell is 2-5 nm. The silica is included outside the metal oxide inner shell, and specifically, a uniform coating layer can be formed by a sol-gel method, the shell can isolate the metal oxide from the external environment, avoid material degradation caused by photocatalytic reaction, and the silica shell is controlled in the range of 2-5 nm in thickness, which completely covers the surface active sites of the metal oxide while ensuring light transmission and inhibits the photocatalytic side reaction.

[0038] Further, the silane compound includes at least one of methyltrimethoxysilane, ethyltriethoxysilane and vinyltrimethoxysilane, and in specific implementation, different functional groups such as methyl or vinyl can be selected to regulate the crosslinking network density and hydrophobic performance, so that stable chemical bonds are formed with the cation adsorption phase and the light stabilization phase.

[0039] Correspondingly, the application also provides a preparation method of the composite anti-blooming agent, which comprises the following steps: The zeolite is crushed and passed through a 200-mesh sieve, and then is added into a hydrochloric acid solution with a concentration of 10-20% according to a solid-liquid ratio of 1:4, stirred at 70-90℃ for 1-3h, filtered and washed until neutral, and then dried at 120℃; the dried product is added into an ethanol solution containing a silane coupling agent, refluxed at 60-70℃ for 3-5h, filtered, washed with ethanol for 3 times, and then vacuum dried to obtain the cation adsorption phase; The nano metal oxide particles are dispersed in ethanol, and ultrasonic treatment is performed for 30min to obtain a dispersion liquid; the mixed solution of ethyl silicate and ethanol with a volume ratio of 1:4 is added dropwise into the dispersion liquid, ammonia water is used to adjust the pH of the system to 8-10, and stirring is performed at 50-60℃ for 2-4h; after aging for 24h, centrifugal separation is performed, and then ethanol washing and drying at 60℃ are performed to obtain the light stabilization phase; The cation adsorption phase and the light stabilization phase are added into deionized water, and stirring adsorption is performed at 60-70℃ for 4-6h; after filtration and drying, the silane compound is added, stirring reaction is performed at 80-90℃ for 2-4h, and then filtration and drying are performed; the product is crushed and passed through a 200-mesh sieve to obtain the composite anti-blooming agent.

[0040] Specifically, the zeolite forms a porous framework structure after being crushed and acid-activated, and its expanded pore size and surface hydroxyl groups provide a basis for subsequent loading of a light-stable phase. The preparation of the light-stable phase forms a uniform silica coating layer by controlling the hydrolysis rate of ethyl silicate, avoiding the photocatalytic side reactions caused by direct exposure of metal oxides. The cation-adsorbing phase and the light-stable phase are physically combined by hydrothermal adsorption, and then a hydrophobic network is formed through the condensation reaction of silane compounds, finally constructing a three-phase composite structure with adsorption, light stability, and hydrophobicity synergistic effects.

[0041] In some embodiments, the concentration of the silane coupling agent in the ethanol solution is 5-8%; The dropwise addition rate of the ethyl silicate and ethanol mixture is 0.5-1.0 mL / min.

[0042] In this embodiment, in the light-stable phase preparation stage, by controlling the dropwise addition rate of the ethyl silicate mixture, the diffusion rate of ethyl silicate in ethanol is matched with the hydrolysis reaction rate, thereby forming a uniform thickness silica shell on the surface of metal oxide particles. In the hydrophobic phase construction stage, the amount of silane compound added directly affects the density of the three-dimensional cross-linked network. When the amount is less than the amount of zeolite added, it may not be able to completely cover the surface of the carrier, and when it exceeds 2 times the amount of zeolite added, it is easy to cause local agglomeration. Controlling the heating rate can avoid the violent hydrolysis of the reaction system caused by sudden temperature rise, ensuring that the silane compound gradually completes the hydrolysis and stably combines with the surface hydroxyl groups of the carrier.

[0043] Correspondingly, when the metal oxide is TiO2, in addition to the above-mentioned method for preparing the core-shell structure nanocomposite core, it can also be prepared by a sol-gel method. Specifically, when the metal oxide is TiO2, the step of dispersing metal oxide nanoparticles in ethanol is replaced by adding butyl titanate to ethanol, adding 0.001 mol / L nitric acid to adjust the pH to 3-4, and hydrolyzing to obtain a TiO2 sol; the volume ratio of butyl titanate to ethanol is 1:4-6.

[0044] Titanium butylate as a precursor of TiO2 sol, through hydrolysis reaction to generate nano TiO2 particles, its hydrolysis process is carried out in acidic conditions to control the crystal structure. By adjusting the mixing ratio of titanium butylate and ethanol to control the viscosity and dispersion stability of the sol, too high volume ratio may cause the sol to agglomerate, too low may affect the reaction rate. In the pH 3-4 range, it promotes the hydrolysis of titanium butylate to generate anatase TiO2, which has higher ultraviolet light absorption efficiency than hexagonal ZnO or cubic CeO2. When preparing a light stable phase, after mixing titanium butylate and ethanol in proportion, adjust the pH of the system to 3-4 by nitric acid to promote the hydrolysis of titanium butylate to generate anatase TiO2 sol. The sol is directly used for the subsequent hydrolysis reaction of ethyl silicate, and in the process of silica shell coating, the nanoparticles in the TiO2 sol are wrapped as the core to form a core-shell structure. Compared with the traditional mechanical dispersion method of nanoparticles, the TiO2 particles generated by sol-gel method have more uniform particle size, and the problem of particle agglomeration is avoided by in-situ hydrolysis, thereby improving the loading efficiency of the light stable phase on the surface of the cation adsorption phase.

[0045] Correspondingly, the application also provides an anti-alkali bleeding and yellowing-resistant colored finishing mortar, which comprises Portland cement, metakaolin, white carbon black, graded quartz sand, pigment, sodium hexametaphosphate, polymer latex powder, wood fiber, expanding agent, ultraviolet absorber, cellulose ether and composite anti-alkali bleeding agent.

[0046] Specifically, the application uses white Portland cement as cementitious material, and cooperates with active mineral admixture metakaolin to improve the compactness of the paste. The nano-sized particles of microsilica powder enter the interlayer gap of metakaolin, and the active ingredients can synergistically react to generate corrosion-resistant high-strength C-A-S-H and C-S-H composite gel, thereby reducing the porosity and capillary water absorption.

[0047] The ultraviolet absorber used in the application can shield the UV band and selectively absorb ultraviolet rays with a wavelength of 290-400 nm. Through energy level transition, the light energy is converted into heat energy and released. Combined with high-stability inorganic pigments, the chemical structure of inorganic pigments is stable, and the molecules do not contain organic bonds that are easily damaged by ultraviolet rays. After long-term exposure to sunlight, discoloration is less likely to occur. The crystal structure can remain stable at 300℃, and the alkali resistance is >pH13. It can effectively avoid the color difference caused by photodegradation. At the same time, inorganic pigments do not participate in the hydration process of cement and do not affect the formation of C-S-H gel, so they do not reduce the compressive strength, bonding strength or crack resistance of the mortar.

[0048] The application uses sodium hexametaphosphate to optimize the workability and apparent quality of the mortar. Cement particles are prone to flocculate into groups in water, reducing the uniformity of the paste and increasing the water demand. The anion groups ([Na5P6O 18 ] -) by electrostatic repulsion and steric hindrance effect, forming a negative charge layer on the surface of cement particles, making the particles repel each other, wrapping the pigment / filler particles, preventing agglomeration, releasing free water in the flocculation structure, reducing the amount of mixing water, improving the fluidity of the paste, making the construction smoother, reducing the batch scraping resistance, while sodium hexametaphosphate and calcium ions in cement form a soluble complex ([CaP6O 2+ ), consume calcium ions produced by early hydration, reduce efflorescence from the source. 18 ] 3- )

[0049] The present application uses hydroxyethyl methyl cellulose ether to provide moderate water retention, and the hardening of decorative mortar depends on the hydration reaction of cement and other cementitious materials. Hydration requires continuous water supply to make cement particles fully react with water to generate more hydration products (such as C-S-H gel), improve the bonding strength and surface hardness of the mortar, and reduce cracking caused by insufficient hydration in the later stage. The hydroxyl groups (-OH) on the molecular chain of hydroxyethyl methyl cellulose ether can significantly slow down the evaporation rate of water in the mortar by hydrogen bonding with water molecules. At the same time, hydroxyethyl methyl cellulose ether gives the mortar the property of "shear thinning". When stirring or applying, the molecular chains are disentangled, and the viscosity is temporarily reduced, making it easy to spread and level. When left standing, the molecular chains re-entangle and the viscosity returns, preventing deformation due to gravity flow. This property makes it easier for construction personnel to control surface flatness and reduces the workload of repeated repairs. At the same time, hydroxyethyl methyl cellulose ether has a higher gel temperature and can still extend the open time in an environment above 35°C, significantly reducing plastic shrinkage cracks caused by rapid water evaporation.

[0050] The present application uses graded quartz sand 40-120 mesh continuous grading. The rigid skeleton formed by the medium-coarse particles can anchor the mortar structure, buffer the shrinkage stress of fine particles and cementitious materials, and reduce the generation of dry shrinkage cracks. At the same time, the dense structure reduces the water infiltration channel, avoids surface spalling caused by freeze-thaw cycles, enhances the frost resistance and weather resistance of the mortar, ensures long-term stability of the decorative effect, and the dense structure of graded sand reduces the voids, allowing the pigment to adhere more uniformly to the sand particle surface, ensuring uniform pigment dispersion (color difference ΔE <1.5), avoiding color spots caused by large voids, and ensuring consistent color and luster of the decorative surface.

[0051] The silane-based water repellent agent in the anti-efflorescence agent of the present application forms a hydrophobic film in the capillary pore, and the zeolite adsorbs free Ca 2+The alkali source is reduced, nano-silicon dioxide reacts with Ca(OH)2 to generate C-S-H gel, the reaction formula is SiO2Ca(OH)2→C-S-H), consumes the alkali source and compacts the microstructure, the metal oxide / SiO2 shields ultraviolet rays while avoiding the photocatalytic side effect, and the alkali source path is triplely blocked. The methyltrimethoxysilane forms a coating or film with a three-dimensional cross-linked network structure through hydrolysis-condensation reaction. A stable Si-O-Si covalent bond network is constructed, the silanol group can be covalently combined with the substrate surface hydroxyl group to form a chemical bond, so that the cross-linked layer is tightly attached to the substrate and is not easy to fall off, the release of active components can be delayed, the effective period is long, the powder particle size matches the cement, and the workability of the mortar is not affected.

[0052] Through the above technical solutions, the application can effectively reduce the migration of free calcium ions generated by cement hydration to the surface to form white frost, inhibit the color fading caused by the degradation of organic components induced by ultraviolet rays, and reduce the water permeation rate through the hydrophobic network. The mortar can maintain color stability in a humid environment and delay the yellowing process under long-term light conditions, and both decorative effect and service life are considered.

[0053] Further, the alkali-resistant and yellowing-resistant colored finishing mortar described above, the addition amount of each component is respectively: portland cement 20-35wt%; metakaolin 3-8wt%; white carbon black 1-3wt%; graded quartz sand 50-70wt%; pigment 0.5-3wt%; sodium hexametaphosphate 0.05-0.3wt%; polymer latex powder 2-6wt%; wood fiber 0.2-0.8wt%; expanding agent 0.5-3wt%; ultraviolet absorber 0.2-0.5wt%; cellulose ether 0.15-0.3wt%; composite anti-alkali agent 0.5-3wt%.

[0054] Further, the specific surface area of the metakaolin is ≥500m 2 / kg; The specific surface area of the white carbon black is ≥500m 2 / kg, and the silicon dioxide content is ≥95%; The ultraviolet absorber is a benzotriazole compound with a purity of ≥99%; The cellulose ether is hydroxyethyl methyl cellulose ether with a Brookfield viscosity of 10000-15000cP; The polymer emulsion powder is a hydrophobic vinyl acetate-vinyl ester-ethylene terpolymer, the bulk density is 400-550 kg / m3, and the minimum film forming temperature is 0℃; The length of the wood fiber is 0.5-3 mm, and the bulk density is 20-60 g / L; The expanding agent is a calcium aluminate system expanding agent; The purity of the sodium hexametaphosphate is ≥65%, the content of phosphorus pentoxide calculated as an oxide is ≥68%, and the water-insoluble substance is ≤0.1%.

[0055] In some specific embodiments, the calcium aluminate system expanding agent can be a calcium sulphoaluminate compound, for example, a calcium sulphoaluminate-calcium oxide composite system, the hydration product of which can compensate for shrinkage stress. The length range of the wood fiber is controlled by grading and screening, for example, short fibers of 0.5-1.0 mm are compounded with long fibers of 1.0-3.0 mm to form a three-dimensional network structure to enhance crack resistance. The purity index of the sodium hexametaphosphate is achieved by recrystallization process, for example, secondary crystallization method is used to remove metal ion impurities to ensure stable dispersant efficiency.

[0056] Correspondingly, the application also provides a preparation method of the alkali bleeding and yellowing resistant colored finishing mortar, comprising the following steps: The composite alkali bleeding resistant agent and 30% of the total amount of the graded quartz sand are added into a hot air activation bin, and pre-mixed under stirring at 50℃ to prepare a first dispersion; The ultraviolet absorber and the white carbon black are mixed in a mass ratio of 1:(3-5), added into an ultrasonic dispersing machine, and then treated by ultrasonic treatment and spray dried with deionized water as a dispersing medium to prepare a second dispersion; The polymer emulsion powder and the pigment are dry-mixed in a horizontal screw ribbon mixer; the first dispersion, the second dispersion and the sodium hexametaphosphate are dry-mixed; and the metakaolin, the portland cement, the remaining 70% of the graded quartz sand and the cellulose ether are dry-mixed to prepare the alkali bleeding and yellowing resistant colored finishing mortar.

[0057] In summary, the composite alkali bleeding resistant agent, the preparation method thereof and the alkali bleeding and yellowing resistant colored finishing mortar provided by the application effectively solve the technical problems of alkali bleeding and yellowing of traditional finishing mortar through the synergistic effect of the three components, i.e., the cation adsorption phase selectively adsorbing calcium ions to reduce alkali bleeding sources, the light stabilization phase absorbing ultraviolet rays to inhibit the degradation of organic components, and the hydrophobic phase constructing a three-dimensional network to block water migration, and have the advantages of significantly improving the durability of the decorative effect.

[0058] The application will be further described below with reference to specific examples.

[0059] Example 1 Immerse 500g of sodium zeolite in 2L of hydrochloric acid solution (concentration 10%), stir at 80℃ for 2h, filter and wash until neutral, and dry at 120℃; add the dried sodium zeolite to an ethanol solution containing 5% γ-aminopropyltriethoxysilane, reflux at 60℃ for 4h; filter, wash 3 times with ethanol, and vacuum dry to obtain the cationic adsorption phase.

[0060] 200g of tetrabutyl titanate was added to ethanol, and 0.001mol / L nitric acid was added dropwise for hydrolysis to obtain TiO2 sol. Ethyl silicate / ethanol mixture (1:4) was slowly added dropwise to TiO2 sol, and ammonia was used as catalyst to bring the pH to 9. After aging for 24h, the mixture was centrifuged, washed with ethanol, and dried to obtain photostable phase powder.

[0061] The photostable phase powder was dispersed in water, and the cationic adsorption phase was added. The mixture was stirred at 60°C for 6 hours for adsorption. 200g of methyltrimethoxysilane was added dropwise to the mixture, and the mixture was reacted at 80°C for 3 hours. The mixture was filtered, dried at 100°C for 2 hours, and pulverized through a 200-mesh sieve to obtain a composite anti-alkali efflorescence agent.

[0062] Example 2 Immerse 500g of clinoptilolite in 2L of nitric acid solution (20% concentration), stir at 90℃ for 1.5h, filter and wash until neutral, and dry at 120℃; add the dried clinoptilolite to an ethanol solution containing 8% 3-mercaptopropyltrimethoxysilane, reflux at 70℃ for 3h; filter, wash 3 times with ethanol, and vacuum dry to obtain the cationic adsorption phase. 50g of nano zinc oxide powder was dispersed in an ethanol solution, and a mixture of ethyl silicate / ethanol (1:4) was added dropwise to the ethanol solution. The pH was adjusted to 9 by ammonia catalysis. After aging for 24h, the powder was separated by centrifugation, washed with ethanol, and dried to obtain the light-stable phase powder. The photostable phase powder was dispersed in water, and the cationic adsorption phase was added. The mixture was stirred at 60°C for 6 hours for adsorption. 200g of methyltrimethoxysilane was added dropwise to the mixture, and the mixture was reacted at 80°C for 3 hours. The mixture was filtered, dried at 100°C for 2 hours, and pulverized through a 200-mesh sieve to obtain a composite anti-alkali efflorescence agent.

[0063] Example 3 Immerse 500g of mordenite in 2L of nitric acid solution (20% concentration), stir at 90℃ for 1.5h, filter and wash until neutral, and dry at 120℃; add the dried clinoptilolite to an ethanol solution containing 8% 3-mercaptopropyltrimethoxysilane, reflux at 70℃ for 3h; filter, wash 3 times with ethanol, and vacuum dry to obtain the cationic adsorption phase. 50g of nano CeO2 powder was dispersed in an ethanol solution, and a mixture of ethyl silicate / ethanol (1:4) was added dropwise to the ethanol solution. The pH was adjusted to 9 by ammonia catalysis. After aging for 24h, the powder was separated by centrifugation, washed with ethanol, and dried to obtain the light-stable phase powder. The light stable phase powder is dispersed in water, the cation adsorption phase is added, and stirring adsorption is carried out at 60℃ for 6h; 100g of vinyl trimethoxysilane is added dropwise to the mixture, and reaction is carried out at 80℃ for 3h; filtration is carried out, drying is carried out at 100℃ for 2h, and crushing is carried out through a 200 mesh sieve to obtain the composite anti-alkali bleeding agent.

[0064] Example 4 1. The decorative mortar is prepared according to the following weight ratio: Silicate cement 28%, composite anti-alkali bleeding agent of Example 1 1.5%, metakaolin 5%, white carbon black 2%, quartz sand 60%, iron oxide red pigment 1.2%, sodium hexametaphosphate 0.15%, polymer latex powder 4%, wood fiber 0.5%, expanding agent 1%, ultraviolet absorber 0.3%, cellulose ether 0.2%.

[0065] 2. Preparation method The composite anti-alkali bleeding agent is premixed with 30% graded quartz sand in a 50℃ hot air activation bin for 5min, the ultraviolet absorber is pre-dispersed with white carbon black in an ultrasonic dispersing machine (frequency 40kHz) for 10min, then computer weighing and feeding are carried out by using an integrated equipment, and the hydrophobic polymer latex powder and inorganic pigment are fed according to the ratio into a 3m 3 horizontal screw belt mixer stirring bin at 100rpm for dry mixing for 3min, then the premixed composite anti-alkali bleeding agent, ultraviolet absorber and white carbon black, sodium hexametaphosphate are continuously mixed at a speed of 120rpm for 3min, finally the metakaolin, white carbon black, silicate cement, remaining graded quartz sand and cellulose ether are added, and stirring is carried out at a speed of 120rpm for 3min to obtain uniform mixing, and the stirring is completed.

[0066] 3. Use method The prepared decorative mortar powder is mixed with water in a container according to a weight ratio of 1:0.22, and a handheld electric mixer is used to stir at 600rpm for 2-3min, then it is statically stopped for 1min, and then it is stirred again for 1-2min to obtain the mortar, the obtained mortar should be constructed within 2h, and it cannot be used after the time, and water or powder cannot be added during the construction; the manual batch scraping method is used during the construction, and the thickness is about 2-3mm.

[0067] Example 5 1. The decorative mortar is prepared according to the following weight ratio: Silicate cement 32%, composite anti-alkali bleeding agent of Example 1 2.8%, metakaolin 3.5%, white carbon black 1.5%, graded quartz sand 55%, phthalocyanine blue pigment 2.5%, sodium hexametaphosphate 0.25%, polymer latex powder 5.5%, wood fiber 0.6%, expanding agent 2.5%, ultraviolet absorber 0.35%, cellulose ether 0.18%.

[0068] 2. Preparation method The composite anti-efflorescence agent is premixed with 30% graded quartz sand in a hot air activation bin at 50°C for 5 minutes, the ultraviolet absorber is pre-dispersed with white carbon black in an ultrasonic disperser (frequency of 40 kHz) for 10 minutes, then the hydrophobic polymer latex powder and inorganic pigments are put into the 3m 3 The horizontal screw ribbon mixer stirring bin is dry mixed at 100 rpm for 3 minutes, then the premixed composite anti-efflorescence agent, ultraviolet absorber and white carbon black, and sodium hexametaphosphate are continuously mixed at a speed of 120 rpm for 3 minutes, finally the metakaolin, white carbon black, Portland cement, the remaining graded quartz sand and cellulose ether are added and stirred at a speed of 120 rpm for 3 minutes to be uniformly mixed, and the stirring is completed.

[0069] 3. Method of use The prepared finishing mortar powder is mixed with water in a container at a weight ratio of 1:0.22, stirred with a handheld electric mixer at 600 rpm for 2-3 minutes, then stopped for 1 minute, and then stirred again for 1-2 minutes to obtain a mortar. The obtained mortar should be used within 2 hours, and water or powder should not be added during use. The mortar is applied by manual batch scraping, with a thickness of about 2-3 mm.

[0070] Example 6 1. The finishing mortar is prepared according to the following weight ratio composition: Portland cement 20%, composite anti-efflorescence agent of example 1 0.8%, metakaolin 7.5%, white carbon black 2.8%, graded quartz sand 68%, titanium-chromium brown pigment 0.8%, sodium hexametaphosphate 0.08%, polymer latex powder 3.2%, wood fiber 0.25%, expanding agent 0.5%, ultraviolet absorber 0.22%, cellulose ether 0.25%.

[0071] 2. Preparation method The composite anti-efflorescence agent is premixed with 30% graded quartz sand in a hot air activation bin at 50°C for 5 minutes, the ultraviolet absorber is pre-dispersed with white carbon black in an ultrasonic disperser (frequency of 40 kHz) for 10 minutes, then the hydrophobic polymer latex powder and inorganic pigments are put into the 3m 3 The horizontal screw ribbon mixer stirring bin is dry mixed at 100 rpm for 3 minutes, then the premixed composite anti-efflorescence agent, ultraviolet absorber and white carbon black, and sodium hexametaphosphate are continuously mixed at a speed of 120 rpm for 3 minutes, finally the metakaolin, white carbon black, Portland cement, the remaining graded quartz sand and cellulose ether are added and stirred at a speed of 120 rpm for 3 minutes to be uniformly mixed, and the stirring is completed.

[0072] 3. Method of use The prepared finishing mortar powder and water are placed in a container at a weight ratio of 1:0.22. The mixture is stirred at 600 rpm for 2-3 minutes with a hand-held electric mixer, then left to stand for 1 minute, and then stirred for another 1-2 minutes to obtain the mortar. The resulting mortar should be applied within 2 hours and should not be used after that time. No water or powder should be added during the process. The mortar should be applied manually to a thickness of about 2-3 mm.

[0073] Example 7 1. The finishing mortar is composed of the following parts by weight: 35% silicate cement, 3% composite anti-alkali efflorescence agent of Example 1, 8% metakaolin, 1% silica fume, 50% graded quartz sand, 3% pigment, 0.3% sodium hexametaphosphate, 6% polymer latex powder, 0.8% wood fiber, 3% expansion agent, 0.5% nano zinc oxide ultraviolet absorber, and 0.15% cellulose ether.

[0074] 2. Preparation method The composite anti-alkali efflorescence agent was premixed with 30% graded quartz sand in a 50℃ hot air activation chamber for 5 minutes. The ultraviolet absorber and silica were pre-dispersed in an ultrasonic disperser (frequency 40kHz) for 10 minutes. Then, using an integrated equipment with computer-controlled weighing and feeding, hydrophobic polymer latex powder and inorganic pigments were added to a 3m³ container according to the specified ratio. 3 Dry mix at 100 rpm for 3 minutes in the mixing chamber of the horizontal ribbon mixer. Then add the premixed composite anti-alkali efflorescence agent, ultraviolet absorber, silica, and sodium hexametaphosphate and continue mixing at 120 rpm for 3 minutes. Finally, add metakaolin, silica, silicate cement, the remaining graded quartz sand and cellulose ether, and mix at 120 rpm for 3 minutes until uniform. After mixing, discharge the material.

[0075] 3. How to use The prepared finishing mortar powder and water are placed in a container at a weight ratio of 1:0.22. The mixture is stirred at 600 rpm for 2-3 minutes with a hand-held electric mixer, then left to stand for 1 minute, and then stirred for another 1-2 minutes to obtain the mortar. The resulting mortar should be applied within 2 hours and should not be used after that time. No water or powder should be added during the process. The mortar should be applied manually to a thickness of about 2-3 mm.

[0076] Example 8 1. The finishing mortar is composed of the following parts by weight: Silicate cement 25%, composite efflorescence inhibitor of example 1 1.2%, metakaolin 4%, white carbon black 2.2%, graded quartz sand 63%, composite iron black / middle chrome yellow pigment 1.5%, sodium hexametaphosphate 0.1%, polymer emulsion powder 4.5%, wood fiber 0.4%, expanding agent 1.8%, ultraviolet absorber 0.28%, cellulose ether 0.28%.

[0077] 2. Preparation method The composite efflorescence inhibitor was premixed with 30% graded quartz sand in a hot air activation bin at 50°C for 5 min, and the ultraviolet absorber was premixed with white carbon black in an ultrasonic dispersing machine (frequency 40 kHz) for 10 min, after which the hydrophobic polymer emulsion powder and inorganic pigment were weighed and fed according to the ratio into a 3m 3 The mixture was dry-mixed in a horizontal screw ribbon mixer stirring bin at 100 rpm for 3 min, and then the premixed composite efflorescence inhibitor, ultraviolet absorber, and white carbon black, sodium hexametaphosphate were added and mixed at a speed of 120 rpm for 3 min, and finally the metakaolin, white carbon black, silicate cement, remaining graded quartz sand, and cellulose ether were added and stirred at a speed of 120 rpm for 3 min to obtain a uniform mixture. After stirring was completed, the mixture was discharged.

[0078] 3. Use method The prepared finishing mortar powder was mixed with water in a container at a weight ratio of 1:0.22, and then stirred with a handheld electric mixer at 600 rpm for 2-3 min, then rested for 1 min, and then stirred again for 1-2 min to obtain a mortar. The obtained mortar should be used within 2 h, and water or powder should not be added during use. During construction, manual batch scraping was used, and the thickness was about 2-3 mm.

[0079] Comparative example 1.

[0080] 1. Finishing mortar composition by weight parts: Silicate cement 30%, metakaolin 5%, white carbon black 2.2%, hydrophobic agent (silane type) 1%, graded quartz sand 58%, iron oxide red pigment 2%, sodium hexametaphosphate 0.2%, polymer emulsion powder 4%, wood fiber 0.3%, expanding agent 1.8%, cellulose ether 0.25%.

[0081] 2. Preparation method The hydrophobic polymer emulsion powder and inorganic pigments are put into a 3m3horizontal screw ribbon mixer stirring bin according to the proportion by using integrated equipment computer weighing and feeding, dry mixing for 3min at 100rpm, then white carbon black and sodium hexametaphosphate are added and continue to mix at 120rpm for 3min, finally metakaolin, white carbon black, Portland cement, hydrophobic agent, graded quartz sand and cellulose ether are added and stirred at 120rpm for 3min until uniformly mixed, and then the stirring is completed and the material is discharged.

[0082] 3. Use method The prepared finishing mortar powder and water are placed in a container in a proportion of 1:0.22 by weight, stirred for 2-3min at 600rpm using a handheld electric mixer, then stand still for 1min, and then stirred for 1-2min, and the mortar is obtained by mixing in this way, the obtained mortar should be completed within 2h, and cannot be used after the time, and water or powder cannot be added during the process; manual batch scraping method is used during construction, and the thickness is about 2-3mm.

[0083] Comparative example 2 1. The composition of the finishing mortar is as follows by weight: Portland cement 15%, aluminate cement 20%, metakaolin 2%, white carbon black 1%, graded quartz sand 56%, phthalocyanine blue organic pigment 2%, sodium hexametaphosphate 0.1%, polymer emulsion powder 3%, wood fiber 0.3%, expanding agent 0.5%, and cellulose ether 0.2%.

[0084] 2. Preparation method The hydrophobic polymer emulsion powder and inorganic pigments are put into a 3m3horizontal screw ribbon mixer stirring bin according to the proportion by using integrated equipment computer weighing and feeding, dry mixing for 3min at 100rpm, then white carbon black and sodium hexametaphosphate are added and continue to mix at 120rpm for 3min, finally metakaolin, white carbon black, Portland cement, aluminate cement, expanding agent, graded quartz sand and cellulose ether are added and stirred at 120rpm for 3min until uniformly mixed, and then the stirring is completed and the material is discharged.

[0085] 3. Use method The prepared finishing mortar powder and water are placed in a container in a proportion of 1:0.22 by weight, stirred for 2-3min at 600rpm using a handheld electric mixer, then stand still for 1min, and then stirred for 1-2min, and the mortar is obtained by mixing in this way, the obtained mortar should be completed within 2h, and cannot be used after the time, and water or powder cannot be added during the process; manual batch scraping method is used during construction, and the thickness is about 2-3mm.

[0086] Performance test The performance test of the anti-efflorescence and yellowing-resistant colored finishing mortar of the present application is performed according to the standard of JC / T 1024-2019 "Wall Finishing Mortar" for cement-based exterior wall finishing mortar (CE), which can be used for exterior wall decoration.

[0087] The performance test of the colored finishing mortar prepared in Examples 4-8 is performed according to JC / T 1024-2019 "Wall Finishing Mortar", and the results are shown in Table 1 as follows: Table 1: Test results of performance test

[0088] As shown in the above table, the colored finishing mortar provided by the present application achieves the following through the following synergistic design: 1. The composite anti-efflorescence system can effectively block capillary pores and fix free Ca after 50°C sand particle coating pretreatment. 2+ Examples 4-8 reduce the 240 min water absorption to 2.3-4.7 g, and the anti-efflorescence is qualified, while the 240 min water absorption of Comparative Example 1 is 6.8 g, and efflorescence occurs in Comparative Examples 1 and 2; 2. The color difference of Examples 4-8 is 1 level after 1000 h xenon lamp aging under the synergistic effect of inorganic pigments and ultraviolet absorbers, which is significantly better than the organic pigment system of Comparative Example 2 (4 level). In Comparative Example 1, the water absorption is 6.8 g at 240 min, which exceeds the standard of ≤5.0 g, and local efflorescence occurs due to the migration of Ca(OH)2 to the surface and carbonization. In Comparative Example 2, the difference in hydration rate of aluminate cement and portland cement causes shrinkage stress, and the insufficient amount of expansion agent leads to cracking; the molecular chain of organic pigment phthalocyanine blue is broken under UV, and the weather resistance is 4 level (far exceeding the upper limit of 2 level of the standard).

[0089] Examples 4-8 achieve 100% qualified rate of efflorescence rate, weather resistance, and strength of the finishing mortar by using three core technologies of composite anti-efflorescence agent to block ion migration, inorganic pigment-ultraviolet absorber synergistic light protection, and cement-expansion agent strength skeleton optimization. Comparative Examples 1-2 prove that the absence, replacement, or breakthrough threshold of any core component will cause a chain collapse of performance.

[0090] To further verify the advantages of anti-efflorescence, durability, and environmental adaptability of the present application, the following special tests are performed, including standard accelerated efflorescence test, cation adsorption phase adsorption performance test, thermal-freeze cycle accelerated aging test, and high-humidity low-temperature environment stability test.

[0091] Standard accelerated efflorescence test Test method: According to the standard of JC / T 1024-2019, 21 cycles of test were carried out by using electrically controlled water spraying device (each cycle: spraying for 10 min, drying at 50°C for 4 h, cooling to room temperature). The test piece size was 150 mm x 70 mm x 3 mm, placed at an angle of 60°, the water spraying hole was 150 mm away from the surface, and the environmental humidity was 70 ± 5%. After 21 cycles, the alkali bleeding area ratio was accurately measured by image analysis method, the surface exudate pH value was measured by pH meter, and the Ca 2+ concentration in the leaching solution was measured by ion chromatography.

[0092] The test results are shown in Table 2: Table 2: Accelerated alkali bleeding test results

[0093] It can be seen that, due to the synergistic effect of the composite anti-alkali bleeding agent, the Ca 2+ ion migration of the embodiments 4-8 of the present application is effectively inhibited, the alkali bleeding area is almost zero, and the system pH value is stable at a low level. The comparative example group is seriously alkali bleeding due to the lack of the synergistic system, and a large amount of alkaline substances are precipitated.

[0094] Adsorption performance test of cation adsorption phase Test method: Static adsorption test was used. The cation adsorption phase prepared in Example 1 and unmodified sodium zeolite were added to CaCl2 solutions with different initial concentrations (25°C, pH = 7), and after oscillation adsorption to equilibrium, the remaining Ca 2+ concentration in the solution was measured, and the adsorption amount was calculated.

[0095] The test results are shown in Table 3: Table 3: Calcium ion adsorption amount

[0096] Test results: The saturated adsorption amount of the cation adsorption phase of Example 1 to Ca 2+ was 82 mg / g, while the saturated adsorption amount of the unmodified sodium zeolite under the same conditions was only 35 mg / g.

[0097] It can be seen that acidification and organic functional group modification can significantly improve the capture ability of zeolite to calcium ions, reducing the alkali bleeding source from the source, and providing core material support for the anti-alkali bleeding effect of the present application.

[0098] Thermal-freeze cycle accelerated aging test Test method: The well-maintained test block (150 mm x 150 mm x 3 mm) was placed in 60°C hot water for 18 h, and then immediately transferred to a -20°C environment for 6 h, which was one cycle. A total of 20 cycles were carried out. After the end, the surface alkali bleeding was observed.

[0099] The test results are shown in Table 4: Table 4: Blooming after heat-freeze cycle

[0100] It can be seen that under the stress of severe temperature change, the present application exhibits excellent durability and anti-blooming stability due to its dense microstructure and flexible polymer network, far superior to traditional formulations.

[0101] High humidity and low temperature environment stability test Test conditions: temperature 5°C, relative humidity 90%, continuous placement for 30 days. After the test, the surface state, blooming and color change (ΔΕ) were evaluated.

[0102] The test results are shown in Table 5: Table 5: High humidity and low temperature environment test results

[0103] It can be seen that under the stress of severe temperature change, the present application exhibits excellent durability and anti-blooming stability due to its dense microstructure and flexible polymer network, far superior to traditional formulations.

[0104] The above has described various embodiments of the present application, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes are obvious to those skilled in the art without departing from the scope and spirit of the described embodiments. The choice of terms used herein is intended to best explain the principles, practical applications, or improvements to the technology in the market of the embodiments, or to enable other ordinary skilled persons in the art to understand the embodiments disclosed herein.

Claims

1. A composite anti-alkali efflorescence agent, characterized in that, Including cationic adsorption phase, photostable phase and hydrophobic phase; The cationic adsorbent phase has a porous framework structure and contains zeolite that has been acid-activated and modified with organic functional groups. The acid activation and organic functional group modification are process steps performed sequentially. The photostable phase is a core-shell structured nanocomposite that is loaded onto the surface and pores of the cationic adsorption phase through physical adsorption or chemical bonding. It comprises a metal oxide core and a silica shell, wherein the metal oxide core is a metal oxide that can absorb ultraviolet light. The hydrophobic phase is a three-dimensional cross-linked network formed by the hydrolysis and condensation reaction of silane compounds, and its silanol groups are covalently bonded to the hydroxyl groups on the surface of the cationic adsorption phase and the photostable phase.

2. The composite anti-alkali efflorescence agent according to claim 1, characterized in that, The mass ratio of the cationic adsorption phase, the photostable phase, and the hydrophobic phase is (8-12):1:(16-24); The zeolite is selected from at least one of sodium zeolite, clinoptilolite, mordenite, and synthetic zeolite. After acid activation, the zeolite has a pore size of 30-100 nm and a specific surface area of ​​300-800 m². 2 / g; The acid activation treatment of the zeolite is performed using hydrochloric acid or nitric acid solution; The organic functional group modification is performed using a silane coupling agent, which is γ-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, or 3-mercaptopropyltrimethoxysilane.

3. The composite anti-alkali efflorescence agent according to claim 1, characterized in that, The metal oxide core is anatase TiO2, hexagonal ZnO or cubic CeO2, with an average particle size of 5-20 nm. The average thickness of the silicon dioxide shell is 2-5 nm; The silane compound includes at least one of methyltrimethoxysilane, ethyltriethoxysilane, and vinyltrimethoxysilane.

4. A method for preparing a composite anti-alkali efflorescence agent as described in any one of claims 1-3, characterized in that, Includes the following steps: Zeolite was crushed and passed through a 200-mesh sieve. It was added to a 10-20% hydrochloric acid solution at a solid-liquid ratio of 1:

4. The mixture was stirred at 70-90℃ for 1-3 hours, filtered, washed until neutral, and dried at 120℃. The dried product was added to an ethanol solution containing a silane coupling agent and refluxed at 60-70℃ for 3-5 hours. After filtration and washing with ethanol three times, the mixture was vacuum dried to obtain the cationic adsorption phase. Nano-sized metal oxide particles were dispersed in ethanol and ultrasonically treated for 30 min to obtain a dispersion. A mixture of ethyl silicate and ethanol with a volume ratio of 1:4 was added dropwise to the dispersion. The pH of the system was adjusted to 8-10 with ammonia. The mixture was stirred at 50-60℃ for 2-4 h, aged for 24 h, centrifuged, washed with ethanol, and dried at 60℃ to obtain a light-stable phase. The cationic adsorbent phase and the photostable phase were added to deionized water and stirred at 60-70℃ for 4-6 hours for adsorption. After filtration and drying, a silane compound was added and stirred at 80-90℃ for 2-4 hours for reaction. After filtration and drying, the mixture was pulverized and passed through a 200-mesh sieve to obtain a composite anti-alkali efflorescence agent.

5. The preparation method of the composite anti-alkali efflorescence agent according to claim 4, characterized in that, In the ethanol solution containing the silane coupling agent, the concentration of the silane coupling agent is 5-8%; The dropping rate of the mixture of ethyl silicate and ethanol is 0.5-1.0 mL / min.

6. The preparation method of the composite anti-alkali efflorescence agent according to claim 4, characterized in that, When the metal oxide is TiO2, the step of dispersing the metal oxide nanoparticles in ethanol is replaced by adding tetrabutyl titanate to ethanol, adjusting the pH to 3-4 by adding 0.001 mol / L nitric acid, and hydrolyzing to obtain TiO2 sol; the volume ratio of tetrabutyl titanate to ethanol is 1:(4-6).

7. A colored decorative mortar resistant to efflorescence and yellowing, characterized in that, It includes silicate cement, metakaolin, silica, graded quartz sand, pigment, sodium hexametaphosphate, polymer latex powder, wood fiber, expanding agent, ultraviolet absorber, cellulose ether, and a composite anti-efflorescence agent as described in any one of claims 1-3, or a composite anti-efflorescence agent prepared by any one of claims 4-6.

8. The alkali-resistant and yellowing-resistant colored decorative mortar according to claim 7, characterized in that, The amounts of each component added, by weight percentage, are as follows: 20-35 wt% silicate cement; Metakaolin 3-8 wt% 1-3 wt% silica; Graded quartz sand 50-70wt%; Pigment 0.5-3wt%; Sodium hexametaphosphate 0.05-0.3 wt%; 2-6 wt% polymer latex powder; Wood fiber 0.2-0.8 wt%; Expanding agent 0.5-3wt%; Ultraviolet absorber 0.2-0.5 wt%; Cellulose ether 0.15-0.3 wt%; Compound anti-alkali agent 0.5-3wt%.

9. The alkali-resistant and yellowing-resistant colored decorative mortar according to claim 8, characterized in that, The specific surface area of ​​the metakaolin is ≥500m². 2 / kg; The specific surface area of ​​the silica is ≥500 m² / kg, and the silica content is ≥95%. The ultraviolet absorber is a benzotriazole compound with a purity ≥99%; The cellulose ether is hydroxyethyl methyl cellulose ether with a Brookfield viscosity of 10,000-15,000 cP. The polymer latex powder is a hydrophobic vinyl acetate-vinyl acetate-ethylene terpolymer with a bulk density of 400-550 kg / m³. 3 The minimum film-forming temperature is 0℃; The wood fibers have a length of 0.5-3 mm and a bulk density of 20-60 g / L; The expanding agent is an ettringite-based expanding agent; The sodium hexametaphosphate has a purity of ≥65%, a phosphorus pentoxide content of ≥68% (calculated as oxides), and water-insoluble matter of ≤0.1%.

10. A method for preparing a colored decorative mortar resistant to efflorescence and yellowing as described in any one of claims 7-9, characterized in that, Includes the following steps: The composite anti-alkali efflorescence agent and 30% of the total amount of graded quartz sand were added to the hot air activation chamber and stirred and premixed at 50°C to obtain the first dispersion. The ultraviolet absorber and silica were mixed at a mass ratio of 1:(3-5), added to an ultrasonic disperser, and treated with deionized water as the dispersion medium. After ultrasonic treatment, the mixture was spray-dried to obtain the second dispersion. The polymer latex powder and pigments are added to a horizontal ribbon mixer for dry mixing; the first dispersion, the second dispersion and sodium hexametaphosphate are added for dry mixing; metakaolin, silicate cement, the remaining 70% graded quartz sand and cellulose ether are added for dry mixing to obtain a colored decorative mortar that is resistant to efflorescence and yellowing.

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