A redispersible latex powder, its preparation method and use

Abstract

The application relates to the technical field of building materials, and discloses a redispersible emulsion powder, a preparation method and application thereof. The redispersible emulsion powder comprises the following raw materials in parts by weight: 45-65 parts of vinyl acetate-ethylene copolymer emulsion, 10-20 parts of styrene-acrylic emulsion, 3-6 parts of protective colloid, 1.3-1.7 parts of bonding enhancement additive, 8-12 parts of anti-caking agent and 35-45 parts of water; the additive comprises glycerol, polyethylene glycol and L-arginine. The technical scheme solves the problem of insufficient bonding performance of the redispersible emulsion powder in the prior art.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, specifically to a redispersible latex powder, its preparation method, and its application. Background Technology

[0002] Redispersible latex powder is a commonly used modifier in the construction industry. It can be redispersed in water and has the same properties as the original emulsion. It is easy to package, small in size, light in weight, and has low transportation costs. When used, it can be directly mixed with raw materials such as cement and gypsum. After the water evaporates, it can form a polymer network structure, which can wrap the aggregate to reduce stress concentration and improve the elasticity and toughness of the rigid skeleton. Therefore, it is widely used in building materials such as cement and mortar.

[0003] As construction projects place increasingly stringent demands on material performance, the existing redispersible latex powders can no longer fully meet the high-standard construction requirements, limiting their application in building insulation, structural bonding, and other scenarios. There is an urgent need to develop a redispersible latex powder with higher adhesion. Summary of the Invention

[0004] This invention proposes a redispersible latex powder, its preparation method, and its application, which solves the problem of insufficient bonding performance of redispersible latex powder in related technologies.

[0005] The technical solution of the present invention is as follows: This invention proposes a redispersible latex powder comprising the following raw materials in parts by weight: 45-65 parts of vinyl acetate-ethylene copolymer emulsion, 10-20 parts of styrene-acrylic emulsion, 3-6 parts of protective colloid, 1.3-1.7 parts of adhesive strengthening agent, 8-12 parts of anti-caking agent, and 35-45 parts of water; The bonding strengthening agent includes glycerol, polyethylene glycol, and L-arginine.

[0006] As a further technical solution, the mass ratio of glycerol, polyethylene glycol and L-arginine is 2:0.5:0.5~1.

[0007] In this invention, when the mass ratio of glycerol, polyethylene glycol, and L-arginine is 2:0.5:0.5~1, the synergistic effect further enhances the adhesion of redispersible latex powder to cement mortar or molded board in practical applications. When the proportion of L-arginine is relatively high, the dispersion stability of the latex powder decreases, making it prone to local agglomeration and weakening the adhesion effect. When the proportion of L-arginine is relatively low, the interfacial bonding force is weak, which also leads to a weakened adhesion effect.

[0008] As a further technical solution, the redispersible latex powder also includes 5 to 10 parts by weight of latex.

[0009] As a further technical solution, the latex includes one of nitrile latex, carboxylated styrene-butadiene latex, carboxylated nitrile latex, and natural latex.

[0010] As a further technical solution, the latex is a carboxylated butadiene-acrylonitrile latex.

[0011] In this invention, when a carboxyl-based nitrile butadiene latex is introduced into a redispersible latex powder, the waterproof performance of the redispersible latex powder in practical applications is greatly improved. The carboxyl-based nitrile butadiene latex contains carboxyl groups and strongly hydrophobic nitrile segments. The carboxyl groups can bond with calcium ions in cement, improving interfacial density; the nitrile segments are highly hydrophobic, forming a continuous, low-absorption, high-density polymer film that blocks water penetration. Simultaneously, the carboxyl-based nitrile butadiene latex has good compatibility with vinyl acetate-ethylene copolymer emulsions and styrene-acrylic emulsions, forming a stable interpenetrating network. Combined with compounding additives, this further enhances film continuity and density, thus significantly improving the waterproof performance of the redispersible latex powder when applied to cement systems.

[0012] As a further technical solution, the protective colloid includes one or both of polyvinyl alcohol and hydroxypropyl methylcellulose ether.

[0013] As a further technical solution, the anti-caking agent includes one or more of heavy calcium carbonate, calcium silicate, and silicon dioxide.

[0014] This invention also proposes a method for preparing redispersible latex powder, comprising the following steps: The raw materials of the redispersible latex powder, excluding the anti-caking agent, are mixed, spray-dried, and the anti-caking agent is added and stirred to obtain the redispersible latex powder.

[0015] As a further technical solution, the mixing time is 40-50 minutes.

[0016] As a further technical solution, the inlet air temperature of the dryer is 140~160℃, and the outlet air temperature is 70~80℃.

[0017] This invention also proposes the application of the redispersible latex powder described above or the redispersible latex powder prepared by the method described above in building concrete and building mortar.

[0018] The working principle and beneficial effects of this invention are as follows: In this invention, glycerol, polyethylene glycol, and L-arginine are compounded and added to redispersible latex powder, resulting in excellent adhesion performance of the redispersible latex powder in practical applications. Glycerol can lower the polymer film-forming temperature, reduce internal stress during the spray drying of latex powder and mortar film formation, prevent film cracking, and simultaneously play a water-retaining and retarding role in cement systems, extending the interfacial wetting and bonding time. Polyethylene glycol can improve the redispersibility of redispersible latex powder, enhance the continuity and flexibility of the film, and synergistically enhance the bonding strength. The amino groups contained in L-arginine form stable coordination bonds with calcium ions generated during cement hydration, improving the interfacial bonding strength between redispersible latex powder and inorganic substrates. The three compounds complement each other, improving the film-forming continuity and interfacial adhesion of the redispersible latex powder. The synergistic effect of these three compounds ultimately results in excellent adhesion of the redispersible latex powder to cement mortar or molded boards in practical applications. Detailed Implementation

[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0020] In the following examples and comparative examples, the following components were used: vinyl acetate-ethylene copolymer emulsion: model 707, solid content ≥55%; styrene-acrylic emulsion: model ROSF-6090, solid content 48±2%; nitrile rubber latex: acrylonitrile content 25%~33%; carboxylated styrene-butadiene rubber latex: model 417, solid content 52%; carboxylated nitrile rubber latex: model FSDB52, solid content 46%; natural rubber latex: model H0101, solid content 60%; polyethylene glycol: model PEG-200; polyvinyl alcohol: model 1788; hydroxypropyl methylcellulose ether: viscosity 100,000; heavy calcium carbonate: average particle size 10μm; calcium silicate: average particle size 10μm; silica: average particle size 5μm.

[0021] Example 1 A redispersible latex powder comprises the following raw materials in parts by weight: 45 parts of vinyl acetate-ethylene copolymer emulsion, 10 parts of styrene-acrylic emulsion, 3 parts of polyvinyl alcohol, 1.3 parts of binder and reinforcing agent, 8 parts of heavy calcium carbonate, and 35 parts of water. The bonding reinforcement agent is glycerol, polyethylene glycol and L-arginine in a mass ratio of 2:0.5:0.25; A method for preparing redispersible latex powder includes the following steps: Vinyl acetate-ethylene copolymer emulsion, styrene-acrylic emulsion, polyvinyl alcohol, adhesive reinforcing agent and water were added to a mixing tank in sequence and mixed for 40 minutes. Then, the mixture was sent to a centrifugal spray tower for spray drying. The inlet air temperature was 140℃ and the outlet air temperature was 70℃. Heavy calcium carbonate was added to the obtained powder and stirred evenly to obtain redispersible latex powder.

[0022] Example 2 A redispersible latex powder comprises the following raw materials in parts by weight: 65 parts vinyl acetate-ethylene copolymer emulsion, 20 parts styrene-acrylic emulsion, 6 parts polyvinyl alcohol, 1.7 parts adhesive reinforcing agent, 6 parts calcium silicate, 6 parts silica, and 45 parts water. The bonding reinforcement agent is glycerol, polyethylene glycol and L-arginine in a mass ratio of 2:0.5:0.25; A method for preparing redispersible latex powder includes the following steps: Vinyl acetate-ethylene copolymer emulsion, styrene-acrylic emulsion, polyvinyl alcohol, hydroxypropyl methylcellulose ether, adhesive reinforcing agent and water were added to a mixing tank in sequence and mixed for 50 minutes. Then, the mixture was sent to a centrifugal spray tower for spray drying. The inlet air temperature was 160℃ and the outlet air temperature was 80℃. Calcium silicate and silica were added to the obtained powder and stirred evenly to obtain redispersible latex powder.

[0023] Example 3 A redispersible latex powder comprises the following raw materials in parts by weight: 55 parts vinyl acetate-ethylene copolymer emulsion, 15 parts styrene-acrylic emulsion, 4.5 parts polyvinyl alcohol, 0.5 parts hydroxypropyl methylcellulose ether, 1.5 parts adhesive reinforcing agent, 3 parts heavy calcium carbonate, 3 parts calcium silicate, 4 parts silica, and 40 parts water. The bonding reinforcement agent is glycerol, polyethylene glycol and L-arginine in a mass ratio of 2:0.5:0.25; A method for preparing redispersible latex powder includes the following steps: Vinyl acetate-ethylene copolymer emulsion, styrene-acrylic emulsion, polyvinyl alcohol, hydroxypropyl methylcellulose ether, adhesive reinforcing agent and water were added sequentially to a mixing tank and mixed for 45 minutes. Then, the mixture was sent to a centrifugal spray tower for spray drying. The inlet air temperature was 150°C and the outlet air temperature was 75°C. Heavy calcium carbonate, calcium silicate and silica were added to the obtained powder and stirred evenly to obtain redispersible latex powder.

[0024] Example 4 The only difference between this embodiment and Embodiment 3 is that the bonding strengthening agent is glycerol, polyethylene glycol and L-arginine in a mass ratio of 2:0.5:0.5.

[0025] Example 5 The only difference between this embodiment and Embodiment 3 is that the bonding reinforcement agent is glycerol, polyethylene glycol and L-arginine in a mass ratio of 2:0.5:1.

[0026] Example 6 The only difference between this embodiment and Example 3 is that the bonding reinforcement agent is glycerol, polyethylene glycol and L-arginine in a mass ratio of 2:0.5:1.25.

[0027] Example 7 The difference between this embodiment and Embodiment 5 lies only in the presence of a redispersible latex powder, comprising the following raw materials in parts by weight: 55 parts vinyl acetate-ethylene copolymer emulsion, 15 parts styrene-acrylic emulsion, 5 parts nitrile latex, 4.5 parts polyvinyl alcohol, 0.5 parts hydroxypropyl methylcellulose ether, 1.5 parts adhesive reinforcing agent, 3 parts heavy calcium carbonate, 3 parts calcium silicate, 4 parts silica, and 40 parts water. A method for preparing redispersible latex powder includes the following steps: Vinyl acetate-ethylene copolymer emulsion, styrene-acrylic emulsion, polyvinyl alcohol, hydroxypropyl methylcellulose ether, adhesive reinforcing agent, nitrile latex and water were added sequentially to a mixing tank and mixed for 45 minutes. Then, the mixture was sent to a centrifugal spray tower for spray drying. The inlet air temperature was 150°C and the outlet air temperature was 75°C. Heavy calcium carbonate, calcium silicate and silica were added to the obtained powder and stirred evenly to obtain redispersible latex powder.

[0028] Example 8 The difference between this embodiment and Embodiment 5 lies only in the presence of a redispersible latex powder, comprising the following raw materials in parts by weight: 55 parts of vinyl acetate-ethylene copolymer emulsion, 15 parts of styrene-acrylic emulsion, 5 parts of carboxylated styrene-butadiene latex, 4.5 parts of polyvinyl alcohol, 0.5 parts of hydroxypropyl methylcellulose ether, 1.5 parts of adhesive reinforcing agent, 3 parts of heavy calcium carbonate, 3 parts of calcium silicate, 4 parts of silica, and 40 parts of water; A method for preparing redispersible latex powder includes the following steps: Vinyl acetate-ethylene copolymer emulsion, styrene-acrylic emulsion, polyvinyl alcohol, hydroxypropyl methylcellulose ether, adhesive reinforcing agent, carboxylated styrene-butadiene latex, and water were sequentially added to a mixing tank and mixed for 45 minutes. The mixture was then sent to a centrifugal spray tower for spray drying, with an inlet air temperature of 150°C and an outlet air temperature of 75°C. Heavy calcium carbonate, calcium silicate, and silica were added to the resulting powder and stirred until homogeneous to obtain redispersible latex powder.

[0029] Example 9 The difference between this embodiment and Embodiment 5 lies only in the presence of a redispersible latex powder, comprising the following raw materials in parts by weight: 55 parts of ethylene-vinyl acetate copolymer emulsion, 15 parts of styrene-acrylic emulsion, 5 parts of carboxylated butadiene-acrylonitrile latex, 4.5 parts of polyvinyl alcohol, 0.5 parts of hydroxypropyl methylcellulose ether, 1.5 parts of adhesive reinforcing agent, 3 parts of heavy calcium carbonate, 3 parts of calcium silicate, 4 parts of silica, and 40 parts of water; A method for preparing redispersible latex powder includes the following steps: Vinyl acetate-ethylene copolymer emulsion, styrene-acrylic emulsion, polyvinyl alcohol, hydroxypropyl methylcellulose ether, adhesive reinforcing agent, carboxylated nitrile latex, and water were sequentially added to a mixing tank and mixed for 45 minutes. The mixture was then sent to a centrifugal spray tower for spray drying, with an inlet air temperature of 150°C and an outlet air temperature of 75°C. Heavy calcium carbonate, calcium silicate, and silica were added to the resulting powder and stirred until homogeneous to obtain redispersible latex powder.

[0030] Example 10 The difference between this embodiment and Embodiment 5 lies only in the presence of a redispersible latex powder, comprising the following raw materials in parts by weight: 55 parts vinyl acetate-ethylene copolymer emulsion, 15 parts styrene-acrylic emulsion, 5 parts natural latex, 4.5 parts polyvinyl alcohol, 0.5 parts hydroxypropyl methylcellulose ether, 1.5 parts adhesive reinforcing agent, 3 parts heavy calcium carbonate, 3 parts calcium silicate, 4 parts silica, and 40 parts water. A method for preparing redispersible latex powder includes the following steps: Vinyl acetate-ethylene copolymer emulsion, styrene-acrylic emulsion, polyvinyl alcohol, hydroxypropyl methylcellulose ether, adhesive reinforcing agent, natural latex and water were added sequentially to a mixing tank and mixed for 45 minutes. Then, the mixture was sent to a centrifugal spray tower for spray drying. The inlet air temperature was 150°C and the outlet air temperature was 75°C. Heavy calcium carbonate, calcium silicate and silicon dioxide were added to the obtained powder and stirred evenly to obtain redispersible latex powder.

[0031] Example 11 The difference between this embodiment and Embodiment 9 lies only in the redispersible latex powder, which includes the following raw materials in parts by weight: 55 parts of vinyl acetate-ethylene copolymer emulsion, 15 parts of styrene-acrylic emulsion, 8 parts of carboxylated butadiene nitrile latex, 4.5 parts of polyvinyl alcohol, 0.5 parts of hydroxypropyl methylcellulose ether, 1.5 parts of adhesive reinforcing agent, 3 parts of heavy calcium carbonate, 3 parts of calcium silicate, 4 parts of silica, and 40 parts of water.

[0032] Example 12 The difference between this embodiment and Embodiment 9 lies only in the redispersible latex powder, which includes the following raw materials in parts by weight: 55 parts of vinyl acetate-ethylene copolymer emulsion, 15 parts of styrene-acrylic emulsion, 10 parts of carboxylated butadiene nitrile latex, 4.5 parts of polyvinyl alcohol, 0.5 parts of hydroxypropyl methylcellulose ether, 1.5 parts of adhesive reinforcing agent, 3 parts of heavy calcium carbonate, 3 parts of calcium silicate, 4 parts of silica, and 40 parts of water.

[0033] Comparative Example 1 The only difference between this comparative example and Example 3 is that the bonding strengthening agent is glycerol and L-arginine in a mass ratio of 2:0.25.

[0034] Comparative Example 2 The only difference between this comparative example and Example 3 is that the bonding reinforcement agent is glycerol and polyethylene glycol in a mass ratio of 2:0.5.

[0035] Comparative Example 3 The only difference between this comparative example and Example 3 is that the bonding strengthening agent is polyethylene glycol and L-arginine in a mass ratio of 0.5:0.25.

[0036] Experimental Example 1 The redispersible latex powder (15 parts) prepared in Examples 1-12 and Comparative Examples 1-3 was mixed with P·O42.5 ordinary silicate cement (300 parts), washed sand (600 parts) and water (200 parts) to obtain mortar samples.

[0037] The mortar samples obtained from the redispersible latex powder prepared in Examples 1-6 and Comparative Examples 1-3 were tested for tensile bond strength with cement mortar and molded polystyrene board according to the test method in GB / T29906-2013 "Materials for Thin Plastering Exterior Wall Insulation System with Molded Polystyrene Board". The test results are shown in Table 1. Table 1. Performance test results of mortar samples obtained from redispersible latex powders prepared in Examples 1-6 and Comparative Examples 1-3.

[0038] 1. Compared with Comparative Examples 1-3, the tensile bond strength between the mortar and cement mortar prepared by the redispersible latex powder obtained in Examples 1-6 was increased to 0.88-1.14 MPa, and the tensile bond strength with the molded board was increased to 0.13-0.20 MPa. This indicates that the addition of glycerol, polyethylene glycol and L-arginine to the redispersible latex powder improved the adhesion of the redispersible latex powder to various substrates in practical applications.

[0039] 2. Compared with Examples 3 and 6, the tensile bond strength of the mortar prepared by the redispersible latex powder obtained in Examples 4 and 5 to cement mortar is increased to 1.12-1.14 MPa, and the tensile bond strength with molded board is increased to 0.19-0.20 MPa. This indicates that limiting the mass ratio of glycerol, polyethylene glycol and L-arginine to 2:0.5:0.5-1 can further improve the adhesion of redispersible latex powder to various substrates in practical applications.

[0040] Experimental Example 2 The mortar samples obtained from the redispersible latex powders prepared in Examples 5 and 7-12 were tested according to the test methods in DL / T5126-2001 "Test Procedure for Polymer Modified Cement Mortar". The water absorption rate of the mortar samples after 7 days was tested, and the test results are shown in Table 2. Table 2 Performance test results of mortar samples obtained from redispersible latex powders prepared in Examples 5 and 7-12

[0041] Compared with Examples 5 and 7-12, the mortar prepared by the redispersible latex powders obtained in Examples 9 and 11-12 had a lower 7-day water absorption rate than that of Examples 5, 7-8 and 10, indicating that adding carboxylated nitrile latex to redispersible latex powder can improve the waterproofness of redispersible latex powder in practical applications.

[0042] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A redispersible latex powder, characterized in that, The raw materials include the following parts by weight: 45-65 parts of vinyl acetate-ethylene copolymer emulsion, 10-20 parts of styrene-acrylic emulsion, 3-6 parts of protective colloid, 1.3-1.7 parts of adhesive strengthening agent, 8-12 parts of anti-caking agent, and 35-45 parts of water; The bonding strengthening agent includes glycerol, polyethylene glycol, and L-arginine.

2. The redispersible latex powder according to claim 1, characterized in that, The mass ratio of glycerol, polyethylene glycol, and L-arginine is 2:0.5:0.5~1.

3. The redispersible latex powder according to claim 1, characterized in that, The redispersible latex powder also includes 5 to 10 parts by weight of latex; The latex includes one of nitrile latex, carboxylated styrene-butadiene latex, carboxylated nitrile latex, and natural latex.

4. The redispersible latex powder according to claim 3, characterized in that, The latex is a carboxylated nitrile latex.

5. The redispersible latex powder according to claim 1, characterized in that, The protective colloid includes one or both of polyvinyl alcohol and hydroxypropyl methylcellulose ether.

6. The redispersible latex powder according to claim 1, characterized in that, The anti-caking agent includes one or more of heavy calcium carbonate, calcium silicate, and silicon dioxide.

7. A method for preparing a redispersible latex powder, used to prepare the redispersible latex powder according to any one of claims 1 to 6, characterized in that, Includes the following steps: The raw materials of the redispersible latex powder, excluding the anti-caking agent, are mixed, spray-dried, and the anti-caking agent is added and stirred to obtain the redispersible latex powder.

8. The method for preparing a redispersible latex powder according to claim 7, characterized in that, The mixing time is 40-50 minutes.

9. The method for preparing a redispersible latex powder according to claim 7, characterized in that, The inlet air temperature of the dryer is 140~160℃, and the outlet air temperature is 70~80℃.

10. The application of a redispersible latex powder according to any one of claims 1 to 6 or a redispersible latex powder prepared by the preparation method according to any one of claims 7 to 9 in building concrete and building mortar.

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