A surface anti-cracking reinforcing curing agent for stucco gypsum, a preparation method and application thereof

Abstract

The application provides a powdering plaster surface anti-cracking reinforcing curing agent, a preparation method and application thereof, and comprises the following components in parts by weight: an aluminate crystallization promoter: 0.5-2.5 parts; an aluminum potassium sulfate crystal nucleus inducer: 0.5-2.5 parts; calcium sulfate dihydrate whisker: 0.3-1.0 parts; an aqueous emulsion polymer: 2-8 parts; a dispersing agent: 0.3-1.2 parts; a thickening agent: 0.05-0.5 parts; a defoaming agent: 0.01-0.1 parts; a gypsum hydration synergist: 0.05-0.3 parts; and water: 80-95 parts. Compared with the prior art, the powdering plaster surface anti-cracking reinforcing curing agent in the application realizes a double breakthrough of crystallization quality and anti-cracking performance, and the strength and interface bonding friendliness are significantly improved, can inhibit later moisture return and whitening, has strong adaptability in the whole construction cycle, improves the convenience of construction, and has remarkable economic benefits.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, and in particular relates to a surface crack-resistant and reinforcing agent for plaster, its preparation method and application. Background Technology

[0002] In building decoration and renovation projects, plaster is a core material for wall and ceiling decoration due to its excellent workability and outstanding fireproof and thermal insulation properties. The performance of plaster directly depends on the crystallization quality of "hemihydrate gypsum → dihydrate gypsum" during its hydration process. However, there are three major technical challenges in actual construction: First, during the plastic stage, wind and high temperatures cause rapid evaporation of moisture, disrupting the crystallization environment, causing crystal growth distortion, and resulting in shrinkage cracking. Second, when microcracks and whitening appear on the surface, the incompletely hydrated crystal structure is loose, leading to insufficient surface strength and crystal defects at the interface with subsequent construction layers. Third, when applying the next layer of material to a dry surface, the porous structure causes rapid moisture migration, disrupting the crystallization process of the next layer of plaster, resulting in insufficient strength and dehydration powdering.

[0003] Currently, existing plastering maintenance materials on the market have two main limitations: firstly, water-retaining products designed for cement-based plaster do not consider the unique characteristics of gypsum crystallization and cannot control the crystallization process; secondly, dry powder interface agents for gypsum require on-site mixing with water, which can easily lead to uneven dispersion and functional failure due to mixing errors, and are unsuitable for controlling crystallization during the plastic stage. There is a technological gap in the industry regarding dedicated liquid-type curing agents for plaster. Problems such as plastic cracking and dehydration / powdering under extreme conditions can only be solved by scraping and re-plastering, resulting in extended construction periods, material waste, and increased costs. Therefore, the development of liquid-type crack-resistant and reinforcing curing agents based on gypsum crystallization control has become an urgent industry need. Summary of the Invention

[0004] The purpose of this invention is to provide a surface crack-resistant and reinforcing curing agent for plaster, its preparation method and application. The curing agent of this invention can accelerate setting, prevent plastic dehydration and cracking, and enhance surface strength and interface layer adhesion. At the same time, it covers three major construction scenarios: new plastering, surface defect repair and dry surface pretreatment, solving the technical pain points of existing curing agents with single function and poor adaptability.

[0005] This invention provides a surface crack-resistant and protective agent for plaster, comprising the following components in parts by weight:

[0006] Aluminate crystallization promoter: 0.5~2.5 parts;

[0007] Sulfate crystal nucleation inducer: 0.5~2.5 parts;

[0008] Inorganic whiskers: 0.3~1.0 parts;

[0009] Aqueous emulsion polymer: 2-8 parts;

[0010] Dispersant: 0.3~1.2 parts;

[0011] Thickener: 0.05~0.5 parts;

[0012] Defoamer: 0.01~0.1 parts;

[0013] Gypsum hydration synergist: 0.05~0.3 parts;

[0014] Water: 80-95 parts;

[0015] The aluminate crystallization promoter includes one or more of calcium aluminate, sodium metaaluminate, potassium aluminate, and polyaluminate.

[0016] The sulfate-based nucleation inducing agents include one or more of potassium aluminum sulfate, ammonium aluminum sulfate, and ferric sulfate.

[0017] The inorganic whiskers include calcium sulfate dihydrate whiskers and / or calcium carbonate whiskers.

[0018] Preferably, the mass ratio of the aluminate crystallization promoter, the sulfate crystal nucleation inducer, and the inorganic whiskers is 1:(0.5~2):(0.3~0.6).

[0019] Preferably, the waterborne emulsion polymer has a weight-average molecular weight of 10,000 to 50,000, a particle size of 0.1 to 1 μm, and a solid content of 40 to 50%.

[0020] Preferably, the aqueous emulsion polymer comprises a first emulsion and a second emulsion;

[0021] The first emulsion comprises an acrylate emulsion and / or a methyl methacrylate-butyl acrylate copolymer emulsion; the second emulsion comprises a polyvinyl acetate emulsion and / or an ethylene-vinyl acetate emulsion; the mass ratio of the first emulsion to the second emulsion is 1:(0.8~1.2).

[0022] Preferably, the dispersant is sodium polyacrylate and / or a polycarboxylate dispersant;

[0023] The thickener includes hydroxypropyl methylcellulose and / or hydroxyethyl cellulose;

[0024] The defoaming agent includes polyether-modified silicone defoaming agents and / or organosilicon-polyether copolymer defoaming agents;

[0025] The gypsum hydration synergist includes a calcium chloride modifier.

[0026] This invention provides a method for preparing the anti-cracking and reinforcing protective agent for plaster surfaces as described above, comprising the following steps:

[0027] A) Mix the dispersant with water at 25~35℃;

[0028] B) Add the thickener and gypsum hydration synergist, and stir to mix;

[0029] C) Add inorganic whiskers and disperse by stirring at 30~32℃;

[0030] D) Add aluminate crystallization promoters and sulfate crystal nucleation inducers, and stir and mix at 30~35℃;

[0031] E) Cool to 25~30℃, add the aqueous emulsion polymer, and stir to mix;

[0032] F) Add defoamer, stir and mix, and let stand to obtain a surface crack-resistant and protective agent for plaster.

[0033] Preferably, in step A), the stirring speed is 300~400 r / min and the stirring time is 5~8 min;

[0034] In step B), the stirring speed is 300~400 r / min and the stirring time is 10~15 min;

[0035] In step C), the stirring speed is 450~500 r / min, and the stirring time is 10~15 min;

[0036] In step D), the stirring speed is 450~500 r / min, and the stirring time is 15~20 min;

[0037] In step E), the stirring speed is 350~450 r / min, and the stirring time is 20~25 min;

[0038] In step F), the stirring speed is 200~300 r / min, and the stirring time is 5~10 min;

[0039] This invention provides the application of the anti-cracking and strengthening curing agent for plaster surface as described above on newly plaster surface;

[0040] The newly applied plaster is plaster applied within 0-30 minutes of application.

[0041] This invention provides the application of the surface crack-resistant and protective agent for plaster as described above in repairing surface defects of plaster.

[0042] This invention provides the application of the anti-cracking and reinforcing curing agent for plaster surface as described above on the surface of dried plaster;

[0043] The moisture content of the dried plaster is ≤5%.

[0044] Compared with the prior art, the anti-cracking and reinforcing agent for plaster surface in this invention has the following advantages:

[0045] (1) Dual breakthroughs in crystallization quality and crack resistance: Through the whole process of crystallization control of “nucleation induction - growth acceleration - whisker reinforcement”, the crystal structure is more uniform and dense; under extreme construction environment (such as high temperature and strong wind), it can significantly improve plastic crack resistance, fundamentally solving the problem of shrinkage cracking caused by rapid evaporation of moisture and destruction of crystallization environment in the plastic stage.

[0046] (2) Significantly improved strength and interfacial bonding: This invention constructs an interpenetrating network structure of inorganic whisker reinforcement and aqueous emulsion organic phase. It not only effectively repairs the crystal defects of incomplete hydration and greatly improves the surface hardness and powdering resistance of the dried gypsum, but also improves the interfacial wettability, making the next process of application smoother. The interfacial bonding reaches an excellent level, completely solving the problems of surface sanding and interlayer peeling.

[0047] (3) Strong adaptability throughout the construction cycle: It covers three core scenarios: new plastering (crystallization start-up control), defect repair (secondary crystallization reinforcement), and dry surface pretreatment (crystallization environment stabilization), realizing integrated maintenance of "crystallization control-defect repair-interface sealing", breaking through the limitation of the single function of existing materials, eliminating the need to replace maintenance products, and improving construction efficiency.

[0048] (4) Suppressing late-stage dampness and whitening: The innovative use of calcium chloride modified material as a hydration synergist, through the complexation effect of organic ligands, avoids the problems of excessively high local ion concentration and strong hygroscopicity caused by unmodified soluble salts. This not only ensures the dense growth of crystals, but also prevents dampness and whitening during the shelf life and long-term use.

[0049] (5) Convenient construction and significant economic benefits: The liquid type can be directly sprayed without on-site mixing, avoiding functional failure caused by mixing errors of dry powder type; effectively avoids rework due to cracking and powdering, reducing material waste and labor costs; the preparation process is simple, the raw materials are readily available, and it is suitable for large-scale industrial production. Detailed Implementation

[0050] This invention provides a surface crack-resistant and protective agent for plaster, comprising the following components in parts by weight:

[0051] Aluminate crystallization promoter: 0.5~2.5 parts;

[0052] Potassium aluminum sulfate crystal nucleation inducer: 0.5~2.5 parts;

[0053] Calcium sulfate dihydrate whiskers: 0.3~1.0 parts;

[0054] Aqueous emulsion polymer: 2-8 parts;

[0055] Dispersant: 0.3~1.2 parts;

[0056] Thickener: 0.05~0.5 parts;

[0057] Defoamer: 0.01~0.1 parts;

[0058] Gypsum hydration synergist: 0.05~0.3 parts;

[0059] Water: 80-95 parts.

[0060] This invention addresses the shortcomings of existing technologies, such as the lack of curing materials suitable for the hydration characteristics of plaster and the insufficient creativity of the "crystallization regulation and polymer synergistic enhancement" scheme. It provides a crack-resistant and reinforcing curing agent based on precise control of the plaster crystallization process. This curing agent, through a synergistic formulation of a "triple crystallization regulation system + specific parameter polymer + special additives," combined with a temperature-controlled stepwise preparation process, achieves precise control over the entire process of plaster crystal nucleation, growth rate, and crystal structure. This accelerates solidification, prevents plastic dehydration cracking, and enhances surface strength and interfacial adhesion. Simultaneously, it covers three major construction scenarios: new plastering, surface defect repair, and dry surface pretreatment, solving the technical pain points of existing curing agents' single function and poor adaptability.

[0061] This invention, based on the crystallization kinetics of gypsum, innovatively designs a triple regulatory system consisting of an aluminate crystallization promoter, a sulfate nucleation inducing agent, and inorganic whiskers. The nucleation inducing agent provides heterogeneous nuclei, the whiskers provide primary nuclei templates, and the crystallization promoter lowers the activation energy and accelerates growth. These three components work synergistically to achieve full-process regulation of nucleation, growth, and reinforcement. This system is specifically designed for gypsum maintenance, breaking through the limitations of traditional single-component crystal control approaches and existing technologies, and solving core problems at the crystal structure level.

[0062] In this invention, the aluminate crystallization promoter can rapidly react with Ca in gypsum. 2+ The reaction generates calcium aluminate hydration products, lowering the crystallization activation energy and accelerating the crystal growth rate. The aluminate crystallization promoter preferably includes one or more of calcium aluminate, sodium aluminate, potassium aluminate, and polyaluminate. Those skilled in the art will understand that, in addition to the specific substances mentioned above, other similar inorganic salts that can provide metal cations and promote rapid reaction to form hydration products can also achieve similar technical effects. The weight percentage of the aluminate crystallization promoter is preferably 0.5 to 2.5 parts, more preferably 1 to 2 parts, such as 0.5 parts, 1 part, 1.5 parts, 2 parts, and 2.5 parts, preferably within the range of any of the above values ​​as the upper or lower limit.

[0063] In this invention, the sulfate nucleation inducer can hydrolyze to release sufficient sulfate ions, accelerating the formation of calcium sulfate dihydrate nuclei with calcium ions in the system; furthermore, when the sulfate nucleation inducer contains Al... 3+ At that time, the Al produced by hydrolysis 3+ It can serve as a heterogeneous nucleus for the crystallization of gypsum dihydrate, optimizing crystal nucleation density and growth orientation. The sulfate-based nucleation inducing agent preferably includes one or more of potassium aluminum sulfate, ammonium aluminum sulfate, and ferric sulfate; the weight fraction of the sulfate-based nucleation inducing agent is preferably 0.5 to 2.5 parts, more preferably 1 to 2 parts, such as 0.5 parts, 1 part, 1.5 parts, 2 parts, 2.5 parts, and preferably within the range of any of the above values ​​as the upper or lower limit.

[0064] In this invention, the inorganic whiskers preferably include calcium sulfate dihydrate whiskers and / or calcium carbonate whiskers. The inorganic whiskers require a regular gypsum dihydrate crystal structure with 100% lattice matching, serving as a "primary nucleus template" to form a dual nucleus system with heterogeneous nuclei. Simultaneously, the fibrous morphology interspersed among the newly formed crystals forms a "crystal-whisker interwoven network," reducing crystal defects. The particle size of the inorganic whiskers is preferably 10~50 μm, and the weight percentage of the inorganic whiskers is preferably 0.3~1.0 parts, more preferably 0.4~0.8 parts, such as 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, and 1.0 parts, preferably within the range of any of the above values ​​as the upper or lower limit.

[0065] In this invention, the mass ratio of the aluminate crystallization promoter, the sulfate crystal nucleation inducer and the inorganic whiskers is 1:(0.5~2):(0.3~0.6), more preferably 1:(1~1.5):(0.4~0.5).

[0066] In this invention, the molecular weight of the aqueous emulsion polymer is preferably 10,000 to 50,000, more preferably 20,000 to 40,000, and the particle size is preferably 0.1 to 1 μm; the solid content is preferably 40 to 50%, more preferably 45 to 50%; the weight fraction of the aqueous emulsion polymer is preferably 2 to 8 parts, more preferably 3 to 7 parts, such as 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, preferably within the range of any of the above values ​​as the upper or lower limit. The aqueous emulsion polymer in this invention is strictly limited to the core parameters of a molecular weight of 10,000 to 50,000 and a particle size of 0.1 to 1 μm. This parameter range ensures that the aqueous emulsion polymer can penetrate into the interstices of gypsum crystals and the surface of whiskers, forming an organic-inorganic interpenetrating network structure with the optimized crystal structure and whiskers. This not only does not interfere with crystal growth but also strengthens crystal defects and improves structural integrity. The crystallization control system ensures a dense and uniform crystal structure, while whiskers reinforce crystal defects and improve structural toughness. The polymer network optimizes interfacial properties. These three elements work synergistically to achieve a triple improvement in crystal strength, structural toughness, and interfacial adhesion, overcoming the functional bottleneck of single control or reinforcement.

[0067] In this invention, the aqueous emulsion polymer comprises a first emulsion and a second emulsion; wherein the first emulsion provides good flexibility and weather resistance, and the second emulsion provides excellent adhesion properties, and the two are combined to synergistically optimize the crystal interface properties. The first emulsion comprises an acrylate emulsion and / or a methyl methacrylate-butyl acrylate copolymer emulsion; the solid content of the first emulsion is preferably 40-50%, more preferably 45-50%, such as 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, preferably within the range of any of the above values ​​as the upper or lower limit; the weight-average molecular weight of the acrylate emulsion and / or the methyl methacrylate-butyl acrylate copolymer in the first emulsion is preferably 10,000-50,000, more preferably 20,000-40,000, and the particle size is preferably 0.1-1 μm; the second emulsion comprises a polyvinyl acetate emulsion and / or an ethylene-vinyl acetate emulsion; the solid content of the second emulsion is preferably... The weight-average molecular weight of the polyvinyl acetate emulsion and / or ethylene-vinyl acetate in the second emulsion is preferably 10,000 to 50,000, more preferably 20,000 to 40,000, and the particle size is preferably 0.1 to 1 μm. The mass ratio of the first emulsion to the second emulsion is preferably 1:(0.8 to 1.2), more preferably 1:(0.9 to 1.1), such as 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, and preferably a range of values ​​with the upper or lower limits of the above-mentioned values. The above-mentioned parameter range of the aqueous emulsion polymer ensures that the polymers in the first emulsion and the second emulsion can penetrate into the gaps between gypsum crystals and the surface of whiskers, and synergistically form an organic-inorganic interpenetrating network structure with the crystals. This does not interfere with crystal growth, but also strengthens crystal defects and improves structural integrity. Among them, the acrylic emulsion provides good flexibility and weather resistance, and the EVA emulsion provides excellent adhesion. The combination of the two synergistically optimizes the crystal interface performance.

[0068] In this invention, the dispersant is sodium polyacrylate (molecular weight 5000~10000) and / or polycarboxylate dispersant. This invention addresses the dispersion requirements of inorganic whiskers and emulsion polymers, with a dosage optimized and increased by 30% compared to conventional systems. This effectively prevents the aggregation of crystallization regulating components and polymers, ensuring uniform dispersion of each functional component and ensuring consistency in crystallization quality and reinforcing effect. The weight percentage of the dispersant is preferably 0.3~1.2 parts, more preferably 0.4~1.0 parts, such as 0.3 parts, 0.4 parts, 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, 1.0 parts, 1.1 parts, and 1.2 parts, preferably within the range of any of the above values ​​as the upper or lower limit.

[0069] In this invention, the thickener includes hydroxypropyl methylcellulose and / or hydroxyethyl cellulose, more preferably hydroxypropyl methylcellulose. The viscosity of the hydroxypropyl methylcellulose is preferably 10,000 to 20,000 mPa·s, which can precisely adjust the viscosity of the curing agent to 200 to 300 mPa·s, adapting to the spraying process, while maintaining the humid environment required for gypsum crystallization and preventing rapid evaporation of water from disrupting the crystallization process. The weight parts of the thickener are preferably 0.05 to 0.5 parts, more preferably 0.1 to 0.4 parts, such as 0.05 parts, 0.1 parts, 0.15 parts, 0.2 parts, 0.25 parts, 0.3 parts, 0.35 parts, 0.4 parts, 0.45 parts, and 0.5 parts, preferably within the range of any of the above values ​​as the upper or lower limit.

[0070] In this invention, the defoamer includes polyether-modified silicone defoamer and / or organosilicon-polyether copolymer defoamer; the defoamer can prevent bubbles generated during preparation and use from remaining in the crystal structure and forming pore defects, thus ensuring crystal density; the weight parts of the defoamer are preferably 0.01 to 0.1 parts, more preferably 0.03 to 0.08 parts, such as 0.01 parts, 0.02 parts, 0.03 parts, 0.04 parts, 0.05 parts, 0.06 parts, 0.07 parts, 0.08 parts, 0.09 parts, 0.1 parts, preferably within the range of any of the above values ​​as the upper or lower limit.

[0071] In this invention, the gypsum hydration synergist can adjust the ion concentration of the gypsum hydration system and compensate for the surface Ca... 2+ The ion balance is maintained by leaching, further optimizing the crystallization kinetics, improving the crystal growth rate and densification degree, and strengthening the synergistic effect between the crystallization control system and the emulsion polymer; the weight part of the gypsum hydration synergist is preferably 0.05~0.3 parts, more preferably 0.1~0.25 parts, such as 0.05 parts, 0.1 parts, 0.15 parts, 0.2 parts, 0.25 parts, 0.3 parts, preferably within the range of any of the above values ​​as the upper or lower limit.

[0072] In this invention, the gypsum hydration synergist preferably includes a calcium chloride modifier. The calcium chloride modifier refers to a composite system obtained by complexing and modifying calcium chloride as the main component with an organic ligand (such as ethylene glycol, triethanolamine, or trisodium citrate). The mass fraction of calcium chloride is preferably 80-90%, such as 80%, 81%, 82%, 83%, 84%, 85%, 86%, 87%, 88%, 89%, or 90%, preferably within the range of any of the above values ​​as the upper or lower limit. The mass fraction of the organic ligand is preferably 10-20%, such as 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, or 20%, preferably within the range of any of the above values ​​as the upper or lower limit.

[0073] In this invention, the modified calcium chloride can avoid the problem of "excessively high local ion concentration" caused by calcium chloride acting solely as an electrolyte. Unmodified calcium chloride will cause the Ca on the gypsum surface to... 2+ Instantaneous enrichment leads to rapid crystal growth but a loose structure; after modification, Ca is slowly released through complexation. 2+ The modified calcium chloride maintains a stable ion activity of 0.01~0.02 mol / L, ensuring uniform and dense crystal growth. It also enhances synergy with the emulsion polymer; the hydrophilic groups of the organic ligand can form hydrogen bonds with the polymer emulsion particles, improving organic-inorganic compatibility, preventing polymer agglomeration, and increasing interfacial bonding strength by 10~15% compared to unmodified calcium chloride. Furthermore, the modified calcium chloride inhibits moisture absorption and whitening, reducing the hygroscopicity of calcium chloride and preventing whitening and sanding of the gypsum surface due to moisture absorption in the later stages, ensuring no moisture absorption during the shelf life.

[0074] In this invention, the water is preferably deionized water to ensure system purity and avoid impurities interfering with the crystallization process and component compatibility; the weight fraction of the water is preferably 80-95 parts, more preferably 85-90 parts.

[0075] This invention provides a method for preparing the crack-resistant and reinforcing protective agent for plaster surfaces described above, comprising the following steps:

[0076] A) Mix the dispersant with water at 25~35℃;

[0077] B) Add the thickener and gypsum hydration synergist, and stir to mix;

[0078] C) Add inorganic whiskers and disperse by stirring at 30~32℃;

[0079] D) Add aluminate crystallization promoters and sulfate crystal nucleation inducers, and stir and mix at 30~35℃;

[0080] E) Cool to 25~30℃, add the aqueous emulsion polymer, and stir to mix;

[0081] F) Add defoamer, stir and mix, and let stand to obtain a surface crack-resistant and protective agent for plaster.

[0082] This invention employs a liquid-type temperature-controlled stepwise feeding process. Targeting the characteristics of the triple crystallization regulation system and the emulsion polymer, it separately sets temperature control for the whisker dispersion step and the emulsion addition stage, precisely adjusting the stirring parameters at each stage to avoid mutual interference between components. The targeted optimization of the dispersant dosage further ensures the uniform dispersion of the crystallization regulation components and the polymer, achieving deep linkage between "formulation-process-crystallization function" and ensuring product performance stability.

[0083] The present invention preferably controls the temperature of deionized water at 25~35℃, and creates a stable initial mixing environment by stirring;

[0084] In this invention, the water temperature of the deionized water is preferably 25~35℃, more preferably 25~30℃, and the stirring speed is preferably 300~400 r / min, more preferably 350~400 r / min.

[0085] Add the dispersant and stir for 5-8 minutes until completely dissolved to ensure uniform dispersion of the dispersant, laying the foundation for the subsequent dispersion of functional components.

[0086] Add thickener and gypsum hydration synergist, stir for 10-15 minutes to form a homogeneous basic system, and adjust the ionic environment of the system to adapt to crystallization control.

[0087] Add inorganic whiskers, maintain the temperature at 30~32℃, and stir at a speed of 450~500r / min for 10~15min to ensure that the whiskers are evenly dispersed and avoid agglomeration;

[0088] Add aluminate crystallization promoters and sulfate crystal nucleation inducers, maintain the temperature at 30~35℃, and stir at a speed of 400~450r / min for 15~20min to avoid local reactions of crystallization regulating components and ensure stable function.

[0089] Cool to 25~30℃, slowly add the aqueous emulsion polymer, and stir at 350~450r / min for 20~25min to ensure uniform emulsion breaking and formation of a stable organic-inorganic composite system with the inorganic components;

[0090] Add defoamer and stir at 200-300 rpm for 5-10 minutes. Let stand for 2-3 minutes to obtain a homogeneous and stable liquid curing agent.

[0091] This invention also provides the application of the plaster surface crack-resistant and reinforcing agent described above. The plaster surface crack-resistant and reinforcing agent of this invention can be applied to three major construction scenarios: new plastering, surface defect repair, and dry surface pretreatment.

[0092] The anti-cracking and strengthening curing agent for plaster surface of the present invention addresses the problem of wind and high temperature damaging the gypsum crystallization environment during the plastic stage of newly applied plaster (within 0-30 minutes of application), which leads to crystal growth distortion and shrinkage cracking. It provides a liquid curing solution that can precisely control the crystallization process and optimize the crystallization environment, thus preventing cracking from the source of crystal nucleation and growth.

[0093] When the anti-cracking and reinforcing protective agent for plaster surface of this invention is applied to a newly plaster surface, pressure spraying is preferred, with the spraying pressure controlled at 0.3~0.5MPa, more preferably 0.35~0.45MPa, and the spraying amount preferably 0.2~0.3kg / m². 2 The triple crystallization regulation system in the curing agent works quickly. The crystal nucleation inducer and whiskers provide dual crystal nuclei, the crystallization promoter accelerates crystal growth, and the water-retaining component maintains a stable crystallization environment, shortening the plasticity time to within 30 minutes, avoiding crystal growth distortion, and preventing cracking from the source.

[0094] The anti-crack strengthening and curing agent for plaster surface in this invention is designed for plaster surfaces with microcracks (width ≤ 0.2 mm) or whitening. It can solve the problems of insufficient surface strength and poor crystal continuity at the interface with subsequent construction layers caused by crystal structure defects such as microcracks and whitening on the plaster surface. By regulating secondary crystallization and strengthening crystals, it can improve surface strength and interface adhesion performance.

[0095] When the anti-cracking and reinforcing agent for plaster surface in this invention is applied to plaster surfaces with micro-cracks or whitening, it is preferable to first clean the surface dust, then use a misting spraying method, with a preferred spraying amount of 0.3~0.4 kg / m². 2 The curing agent penetrates into the crack and onto the surface, providing a secondary crystallization environment. The crystallization control system promotes the continued crystallization and growth of incompletely hydrated gypsum components, with whiskers interpenetrating and reinforcing to fill crystal defects. At the same time, the emulsion polymer forms an interpenetrating network structure with the newly formed crystals, repairing defects and improving surface strength and interfacial adhesion.

[0096] The anti-cracking and strengthening curing agent for plaster surface in this invention is designed for dried plaster surface (moisture content ≤5%). It can solve the problem of rapid water migration caused by the porous structure of the dried plaster surface, which disrupts the crystallization process of the next layer of material, leading to insufficient strength and powdering due to water loss. It stabilizes the crystallization environment through crystal densification and interface sealing.

[0097] When the anti-cracking and reinforcing agent for plaster surface in this invention is applied to a dried plaster surface (moisture content ≤5%), this invention preferably employs a two-coat method, with the first coat preferably applied at a rate of 0.2~0.25 kg / m². 2 After an interval of 30-35 minutes, apply a second coat of 0.1-0.15 kg / m². 2 The triple crystallization regulation system in the curing agent works synergistically with the emulsion polymer to form a dense crystal-whisker-polymer composite protective layer on the surface. This seals the pores, preventing rapid moisture migration from interfering with the crystallization process of the next layer. At the same time, it strengthens the surface crystal structure, acting as a penetrating and reinforcing interface agent to ensure the crystallization quality and strength of the next layer of material.

[0098] This invention provides a surface crack-resistant and protective agent for plaster, comprising the following components in parts by weight: aluminate crystallization promoter: 0.5-2.5 parts; potassium aluminum sulfate crystal nucleation inducer: 0.5-2.5 parts; calcium sulfate dihydrate whiskers: 0.3-1.0 parts; aqueous emulsion polymer: 2-8 parts; dispersant: 0.3-1.2 parts; thickener: 0.05-0.5 parts; defoamer: 0.01-0.1 parts; plaster hydration synergist: 0.05-0.3 parts; water: 80-95 parts.

[0099] Compared with the prior art, the anti-cracking and reinforcing agent for plaster surface in this invention has the following advantages:

[0100] (1) Dual breakthroughs in crystallization quality and crack resistance: Through the whole process of crystallization control of “nucleation induction - growth acceleration - whisker reinforcement”, the crystal structure is more uniform and dense; under extreme construction environment (such as high temperature and strong wind), it can significantly improve plastic crack resistance, fundamentally solving the problem of shrinkage cracking caused by rapid evaporation of moisture and destruction of crystallization environment in the plastic stage.

[0101] (2) Significantly improved strength and interfacial bonding: This invention constructs an interpenetrating network structure of inorganic whisker reinforcement and aqueous emulsion organic phase. It not only effectively repairs the crystal defects of incomplete hydration and greatly improves the surface hardness and powdering resistance of the dried gypsum, but also improves the interfacial wettability, making the next process of application smoother. The interfacial bonding reaches an excellent level, completely solving the problems of surface sanding and interlayer peeling.

[0102] (3) Strong adaptability throughout the construction cycle: It covers three core scenarios: new plastering (crystallization start-up control), defect repair (secondary crystallization reinforcement), and dry surface pretreatment (crystallization environment stabilization), realizing integrated maintenance of "crystallization control-defect repair-interface sealing", breaking through the limitation of the single function of existing materials, eliminating the need to replace maintenance products, and improving construction efficiency.

[0103] (4) Suppressing late-stage dampness and whitening: The innovative use of calcium chloride modified material as a hydration synergist, through the complexation effect of organic ligands, avoids the problems of excessively high local ion concentration and strong hygroscopicity caused by unmodified soluble salts. This not only ensures the dense growth of crystals, but also prevents dampness and whitening during the shelf life and long-term use.

[0104] (5) Convenient construction and significant economic benefits: The liquid type can be directly sprayed without on-site mixing, avoiding functional failure caused by mixing errors of dry powder type; effectively avoids rework due to cracking and powdering, reducing material waste and labor costs; the preparation process is simple, the raw materials are readily available, and it is suitable for large-scale industrial production.

[0105] To further illustrate the present invention, the following detailed description, in conjunction with embodiments, describes a surface crack-resistant and protective agent for plaster, its preparation method, and its application, but this should not be construed as limiting the scope of protection of the present invention.

[0106] Examples 1-5 and Comparative Examples 1-4

[0107] Table 1. Raw material ratios in the examples and comparative examples

[0108]

[0109] In Table 1, the calcium chloride modified product was obtained by modifying triethanolamine and calcium chloride at a mass ratio of 85%:15%.

[0110] Using the raw materials and proportions in Table 1, a plaster surface curing agent was prepared according to the following steps. Comparative Examples 1 to 3 used the controlled variable method to verify the differences in effect when the core component was missing; Comparative Example 4 was the blank group, representing the natural state without any curing agent.

[0111] Add the prescribed amount of deionized water to the reactor, control the temperature at 20℃, and stir at a speed of 350 r / min;

[0112] Add the dispersant and stir for 6 minutes until completely dissolved;

[0113] Add thickener and gypsum hydration synergist, stir for 12 minutes to form a homogeneous base system;

[0114] Add calcium sulfate dihydrate whiskers, maintain the temperature at 31℃, and stir at 480 r / min for 12 min to ensure that the whiskers are evenly dispersed and avoid agglomeration;

[0115] Add aluminate crystallization promoter (sodium aluminate) and potassium aluminum sulfate crystal nucleation inducer, maintain the temperature at 32℃, and stir at 430 r / min for 18 min;

[0116] Cool to 28°C, slowly add the aqueous emulsion polymer, and stir at 400 r / min for 22 min;

[0117] Add defoamer, stir at 250 r / min for 8 min, let stand for 2 min, and you will get a homogeneous and stable liquid curing agent.

[0118] To intuitively and accurately characterize the application effect of the curing agent of this invention in actual construction scenarios, this invention adopts a qualitative grading evaluation system, and the specific rating criteria are as follows:

[0119] 1. Plasticity and crack resistance: Place the newly applied plaster (5mm thick) in a simulated extreme environment of 35℃ and 3m / s wind speed, and observe the surface condition after spraying a curing agent.

[0120] Grade 1 (Excellent): The surface is dense and smooth, with no micro-cracks visible to the naked eye or under a magnifying glass.

[0121] Level 2 (Good): The surface is basically intact, with only a very small number of discontinuous micro-cracks in the edge areas.

[0122] Level 3 (Pass): A few visible cracks appear on the surface, but no deep through cracks appear.

[0123] Level 4 (Unacceptable): Obvious and dense through-shrinkage cracks are present.

[0124] 2. Surface hardness and anti-chalking properties: After the plaster has dried for 7 days, the surface is scratched with a standard hardness scraper to observe the chalking and peeling.

[0125] Grade 1 (Excellent): The surface is hard and solid, with high scratch resistance, leaving only very shallow marks, and no powder or sand shedding.

[0126] Grade 2 (Good): The surface is relatively hard, and there are slight dents when scratched, accompanied by a very small amount of fine powder falling off.

[0127] Level 3 (Qualified): The surface hardness is average, and it can be easily scratched to leave obvious white marks. There is visible powdering and peeling.

[0128] Grade 4 (Unacceptable): The surface is soft and severely powdery, and obvious grooves or structural peeling can be easily scraped out.

[0129] 3. Interface bonding friendliness: After the curing agent is sprayed and dried, a putty application process is performed on the surface to evaluate the application feel and interlayer condition.

[0130] Grade 1 (Excellent): Excellent surface wettability, smooth and lightweight application, perfect interlayer blending, no peeling or bubbles.

[0131] Level 2 (Good): The application is relatively smooth, the interface is tightly bonded, and there is a slight feeling of stickiness in some areas.

[0132] Level 3 (Qualified): The application resistance is relatively high, with occasional slippage or localized tiny air bubbles, but no hollow areas after curing.

[0133] Level 4 (Unacceptable): Excessive sealing or powdering of the interface, severe slippage and peeling during application.

[0134] The test results are shown in Table 2 according to the above rating criteria.

[0135] Table 2 Evaluation of the effects of the examples and comparative examples

[0136]

[0137] The test results from the above examples and comparative examples show that the crack-resistant and reinforcing curing agent of the present invention (Examples 1-5) exhibits excellent performance in all performance indicators. Comparative Example 1 lacks inorganic whiskers, leading to a decrease in structural toughness and a significant drop in surface hardness rating. Comparative Example 2 uses pure calcium chloride instead of the modifying synergist, resulting in local ion imbalance and subsequent whitening, with the interfacial bonding affinity decreasing to level 3. Comparative Example 3 removes the crystallization control system, and relying solely on emulsion sealing is insufficient to resist extreme environments, resulting in extremely poor crack resistance (level 4). Comparative Example 4 demonstrates that without intervention, gypsum itself is highly prone to cracking and severe powdering. The synergistic effect of the formulation of the present invention is significant, perfectly solving the construction pain points in the industry.

[0138] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A surface crack-resistant and protective agent for plaster, comprising the following components in parts by weight: Aluminate crystallization promoter: 0.5~2.5 parts; Sulfate crystal nucleation inducer: 0.5~2.5 parts; Inorganic whiskers: 0.3~1.0 parts; Aqueous emulsion polymer: 2-8 parts; Dispersant: 0.3~1.2 parts; Thickener: 0.05~0.5 parts; Defoamer: 0.01~0.1 parts; Gypsum hydration synergist: 0.05~0.3 parts; Water: 80-95 parts; The aluminate crystallization promoter includes one or more of calcium aluminate, sodium metaaluminate, potassium aluminate, and polyaluminate. The sulfate-based nucleation inducing agents include one or more of potassium aluminum sulfate, ammonium aluminum sulfate, and ferric sulfate. The inorganic whiskers include calcium sulfate dihydrate whiskers and / or calcium carbonate whiskers.

2. The anti-cracking and reinforcing agent for plaster surfaces according to claim 1, characterized in that, The mass ratio of the aluminate crystallization promoter, the sulfate crystal nucleation inducer, and the inorganic whiskers is 1:(0.5~2):(0.3~0.6).

3. The anti-cracking and reinforcing agent for plaster surfaces according to claim 1, characterized in that, The aqueous emulsion polymer has a weight-average molecular weight of 10,000 to 50,000, a particle size of 0.1 to 1 μm, and a solid content of 40 to 50%.

4. The anti-cracking and reinforcing agent for plaster surfaces according to claim 1, characterized in that, The aqueous emulsion polymer includes a first emulsion and a second emulsion; The first emulsion comprises an acrylate emulsion and / or a methyl methacrylate-butyl acrylate copolymer emulsion; the second emulsion comprises a polyvinyl acetate emulsion and / or an ethylene-vinyl acetate emulsion; the mass ratio of the first emulsion to the second emulsion is 1:(0.8~1.2).

5. The anti-cracking and reinforcing agent for plaster surfaces according to claim 1, characterized in that, The dispersant is sodium polyacrylate and / or a polycarboxylate dispersant; The thickener includes hydroxypropyl methylcellulose and / or hydroxyethyl cellulose; The defoaming agent includes polyether-modified silicone defoaming agents and / or organosilicon-polyether copolymer defoaming agents; The gypsum hydration synergist includes a calcium chloride modifier.

6. The preparation method of the anti-cracking and reinforcing agent for plaster surface as described in claim 1, comprising the following steps: A) Mix the dispersant with water at 25~35℃; B) Add the thickener and gypsum hydration synergist, and stir to mix; C) Add inorganic whiskers and disperse by stirring at 30~32℃; D) Add aluminate crystallization promoters and sulfate crystal nucleation inducers, and stir and mix at 30~35℃; E) Cool to 25~30℃, add the aqueous emulsion polymer, and stir to mix; F) Add defoamer, stir and mix, and let stand to obtain a surface crack-resistant and protective agent for plaster.

7. The preparation method of the anti-cracking and reinforcing agent for plaster surface according to claim 6, characterized in that, In step A), the stirring speed is 300~400 r / min and the stirring time is 5~8 min; In step B), the stirring speed is 300~400 r / min and the stirring time is 10~15 min; In step C), the stirring speed is 450~500 r / min, and the stirring time is 10~15 min; In step D), the stirring speed is 450~500 r / min, and the stirring time is 15~20 min; In step E), the stirring speed is 350~450 r / min, and the stirring time is 20~25 min; In step F), the stirring speed is 200~300 r / min, and the stirring time is 5~10 min.

8. The application of the anti-cracking and strengthening curing agent for plaster surface as described in claim 1 on newly plaster surface; The newly applied plaster is plaster applied within 0-30 minutes of application.

9. The application of the anti-cracking and reinforcing agent for plaster surface as described in claim 1 in repairing defects on plaster surface.

10. The application of the anti-cracking and reinforcing agent for plaster surface as described in claim 1 on the surface of dried plaster; The moisture content of the dried plaster is ≤5%.

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