Emulsion for preparing water-resistant redispersible latex powder as well as preparation method and application of emulsion

Abstract

The invention relates to the technical field of redispersible latex powder, and particularly discloses an emulsion for preparing water-resistant redispersible latex powder as well as a preparation method and application of the emulsion. The emulsion for preparing the water-resistant redispersible latex powder disclosed by the invention is specifically prepared from the following components in parts by weight: 380 to 420 parts of water, 20 to 30 parts of polyvinyl alcohol 1792, 2 to 5 parts of an emulsifier NP-30, 3 to 5 parts of a de-foaming agent DM515, 450 to 490 parts of a mixed monomer and 90 to 120 parts of a 4 to 8wt% ammonium persulfate aqueous solution, the mixed monomer is prepared by mixing vinyl acetate, butyl acrylate, vinyl versatate and lauryl methacrylate in a weight ratio of (28-36): (3-8): (3-8): (3-8). The water-resistant redispersible latex powder is prepared from the emulsion, so that the tensile bonding strength and the water resistance of the redispersible latex powder can be effectively improved.

Description

Technical Field

[0001] The present application relates to the technical field of redispersible latex powder, and in particular to an emulsion for preparing water-resistant redispersible latex powder, and a preparation method and application thereof. Background Art

[0002] Redispersible latex powders are made by spray drying a specific emulsion with protective colloids and anti-caking agents. When these powders are mixed with water or mixed with water in mortar, they will produce a dispersion with similar properties to the original latex. The core technology of redispersible latex powders is to make the redispersibility of the powder only occur once, and it cannot be dispersed again when the hardened mortar is exposed to water again. Common redispersible latex powders are polyvinyl acetate ethylene polymers. Since vinyl acetate quickly saponifies in an alkaline environment, it has poor water resistance when used in cement mortar.

[0003] The existing technologies that have been disclosed mostly adopt various emulsion blending or post-mixing with silicone crosslinking agents to prepare water-resistant rubber powder without making any structural changes. Summary of the invention

[0004] In order to solve the above technical problems, the present application provides an emulsion for preparing water-resistant redispersible latex powder, and a preparation method and application thereof.

[0005] The present application provides an emulsion for preparing a water-resistant redispersible latex powder, specifically comprising the following components in parts by weight: 380-420 parts of water, 20-30 parts of polyvinyl alcohol 1792, 2-5 parts of emulsifier NP-30, 3-5 parts of defoamer DM515, 450-490 parts of mixed monomers, and 90-120 parts of 4-8wt% ammonium persulfate aqueous solution; The mixed monomer is composed of vinyl acetate, butyl acrylate, versatate vinyl ester and lauryl methacrylate in a weight ratio of 28-36:3-8:3-8:3-8.

[0006] The present application prepares an emulsion by mixing vinyl acetate, butyl acrylate, versatate vinyl ester and lauryl methacrylate in a specific weight ratio to form a mixed monomer, and then prepares an emulsion with a specific amount of polyvinyl alcohol 1792, emulsifier NP-30, defoamer DM515, 4-8wt% ammonium persulfate aqueous solution initiator and water, and then prepares a water-resistant redispersible latex powder with polyvinyl alcohol 0588 aqueous solution and an anti-caking agent. This technical solution can effectively improve the tensile bonding strength and water resistance of the redispersible latex powder.

[0007] Preferably, the emulsion specifically comprises the following components in parts by weight: 390-410 parts of water, 23-27 parts of polyvinyl alcohol 1792, 3-4 parts of emulsifier NP-30, 3.5-4.5 parts of defoamer DM515, 460-480 parts of mixed monomers, and 100-112 parts of 4-8 wt % ammonium persulfate aqueous solution.

[0008] Preferably, the emulsion specifically comprises the following components in parts by weight: 400 parts of water, 25 parts of polyvinyl alcohol 1792, 3.5 parts of emulsifier NP-30, 4.5 parts of defoamer DM515, 470 parts of mixed monomers, and 106 parts of 6 wt % ammonium persulfate aqueous solution.

[0009] Preferably, the mixed monomer is composed of vinyl acetate, butyl acrylate, vinyl versatate and lauryl methacrylate in a weight ratio of 30-34:4-6:4-6:4-6.

[0010] Preferably, the mixed monomer is composed of vinyl acetate, butyl acrylate, versatate vinyl ester and lauryl methacrylate in a weight ratio of 31-33:4.5-5.5:4.5-5.5:4.5-5.5.

[0011] In a specific embodiment, the weight ratio of vinyl acetate, butyl acrylate, vinyl versatate, and lauryl methacrylate can be 32-36:5:5:5, 36:3-5:8:8, 28:8:3-5:3, 30:4-8:6:6, 34:6:4-8:4.

[0012] In some specific embodiments, the weight ratio of vinyl acetate, butyl acrylate, vinyl versatate, and lauryl methacrylate can also be 32:5:5:5, 36:3:8:8, 28:8:3:3, 30:4:6:6, and 34:6:4:4.

[0013] Through experimental analysis, it can be known that the present application uses the above-mentioned weight ratio of vinyl acetate, butyl acrylate, vinyl versatate, and lauryl methacrylate to form a mixed monomer and then prepare an emulsion, which can further improve the performance of the redispersible latex powder.

[0014] In a second aspect, the present application provides a method for preparing the above-mentioned emulsion for preparing water-resistant redispersible latex powder, which specifically comprises the following steps in sequence: Mix polyvinyl alcohol 1792 and water, raise the temperature to 85-95°C, until the polyvinyl alcohol 1792 is completely dissolved, and then cool down to 73-78°C; Emulsifier NP-30 and defoamer DM515 were added to the reaction system, and nitrogen flow was introduced to maintain an oxygen-free environment; After 8-12 minutes, the mixed monomer and the ammonium persulfate aqueous solution are simultaneously added dropwise by using a peristaltic pump with dual-pass control, and the addition time of the mixed monomer is controlled to be maintained at 2-3 hours, and the addition time of the ammonium persulfate aqueous solution is controlled to be maintained at 3-3.5 hours; during this period, the reaction temperature is controlled at 75-95°C; during this period, the viscosity is observed and the stirring speed is dynamically adjusted; 25-45 minutes after the completion of the dropwise addition of the ammonium persulfate aqueous solution, vacuum treatment is started to remove the residual monomers and then the temperature is cooled to 5-30° C. to obtain the product.

[0015] In a third aspect, the present application provides a water-resistant redispersible latex powder, comprising polyvinyl alcohol 0588, an anti-caking agent and the above-mentioned emulsion.

[0016] Preferably, the anti-caking agent is selected from any one or more of white carbon black and kaolin.

[0017] In a fourth aspect, the present application provides a method for preparing the above-mentioned water-resistant redispersible latex powder, which specifically comprises the following steps in sequence: The emulsion is diluted with water to a solid content of 35-45%, and 85-95 parts by weight are weighed; then, it is evenly mixed with 7-13 parts by weight of a 17-23wt% aqueous solution of polyvinyl alcohol 0588, and transported to a drying device for spray drying, atomized into micro droplets by high-speed centrifugation, 4-10 parts of an anti-caking agent are added, and then the rubber powder particles are cooled and separated to obtain the water-resistant redispersible latex powder.

[0018] Preferably, the latex powder has a particle size of 80-120 meshes.

[0019] In summary, the technical solution of this application has the following effects: The present application prepares an emulsion by mixing vinyl acetate, butyl acrylate, versatate vinyl ester and lauryl methacrylate in a specific weight ratio to form a mixed monomer, and then prepares an emulsion with a specific amount of polyvinyl alcohol 1792, emulsifier NP-30, defoamer DM515, 4-8wt% ammonium persulfate aqueous solution initiator and water, and then prepares a water-resistant redispersible latex powder with polyvinyl alcohol 0588 aqueous solution and an anti-caking agent. This technical solution can effectively improve the tensile bonding strength and water resistance of the redispersible latex powder. DETAILED DESCRIPTION

[0020] The present application is further described in detail below in conjunction with examples, comparative examples and performance testing experiments. These examples should not be construed as limiting the scope of protection claimed in the present application. Example

[0021] Examples 1-5 Examples 1-5 provide an emulsion and a water-resistant redispersible latex powder, respectively.

[0022] The difference between the above embodiments is that the amount of each component used in the emulsion preparation method is different, as shown in Table 1.

[0023] The preparation method of the emulsion in the above embodiment is: Mix polyvinyl alcohol 1792 and water, raise the temperature to 90°C, and cool down to 75°C until the polyvinyl alcohol 1792 is completely dissolved; Emulsifier NP-30 and defoamer DM515 were added to the reaction system, and nitrogen flow was introduced to maintain an anaerobic environment; after 10 minutes, the mixed monomer (the mixed monomer was composed of vinyl acetate, butyl acrylate, tert-butyl vinyl carbonate, and lauryl methacrylate in a weight ratio of 32:5:5:5) and the ammonium persulfate aqueous solution were simultaneously added dropwise using a peristaltic pump with dual-pass control, and the addition time of the mixed monomer was controlled to be 2.5 hours, and the addition time of the ammonium persulfate aqueous solution was controlled to be 3 hours; during this period, the reaction temperature was controlled at 85°C; during this period, the viscosity was observed and the stirring speed was dynamically adjusted; 30 minutes after the completion of the dropwise addition of the ammonium persulfate aqueous solution, vacuum treatment was started to remove the residual monomers and then the temperature was cooled to 20° C. to obtain the product.

[0024] The preparation method of the water-resistant redispersible latex powder in the above embodiment is: dilute the emulsion with water to 40% solid content, weigh 90g; then mix it evenly with 10g of 20wt% polyvinyl alcohol 0588 aqueous solution, transport it to a drying equipment for spray drying, atomize it into micro droplets by high-speed centrifugation at 15000rpm, add 6g of white carbon black anti-caking agent, and then cool and separate the rubber powder particles to obtain a water-resistant redispersible latex powder with a particle size of 80-120 mesh.

[0025] Table 1 Amount of each component in the emulsion preparation method in Examples 1-5 and Comparative Examples 1-2 Embodiment 6-9 Examples 6-9 provide an emulsion and a water-resistant redispersible latex powder, respectively.

[0026] The difference between the above embodiment and embodiment 1 is that the types of mixed monomers are different, as shown below.

[0027] In Example 6: the mixed monomer is composed of vinyl acetate, butyl acrylate, vinyl versatate, and lauryl methacrylate in a weight ratio of 36:3:8:8.

[0028] In Example 7: the mixed monomer is composed of vinyl acetate, butyl acrylate, vinyl versatate, and lauryl methacrylate in a weight ratio of 28:8:3:3.

[0029] In Example 8: the mixed monomer is composed of vinyl acetate, butyl acrylate, vinyl versatate, and lauryl methacrylate in a weight ratio of 30:4:6:6.

[0030] In Example 9: the mixed monomer is composed of vinyl acetate, butyl acrylate, vinyl versatate, and lauryl methacrylate in a weight ratio of 34:6:4:4.

[0031] The remaining process parameters in the above embodiment are the same as those in embodiment 1.

[0032] Examples 10-13 Examples 10-13 respectively provide an emulsion and a water-resistant redispersible latex powder.

[0033] The difference between the above embodiment and embodiment 1 is that the preparation method of the water-resistant redispersible latex powder is different, as shown below.

[0034] In Example 10: The preparation method of water-resistant redispersible latex powder is as follows: dilute the emulsion with water to a solid content of 35%, weigh 90g; then mix it evenly with 10g of a 23wt% aqueous solution of polyvinyl alcohol 0588, transport it to a drying equipment for spray drying, atomize it into micro droplets by high-speed centrifugation at 15000rpm, add 6g of white carbon black anti-caking agent, and then cool and separate the rubber powder particles to obtain a water-resistant redispersible latex powder with a particle size of 80-120 mesh.

[0035] In Example 11: The preparation method of water-resistant redispersible latex powder is as follows: dilute the emulsion with water to 45% solid content, weigh 90g; then mix it evenly with 10g of 17wt% polyvinyl alcohol 0588 aqueous solution, transport it to a drying equipment for spray drying, atomize it into micro droplets by high-speed centrifugation at 15000rpm, add 6g of white carbon black anti-caking agent, and then cool and separate the rubber powder particles to obtain a water-resistant redispersible latex powder with a particle size of 80-120 mesh.

[0036] In Example 12: The preparation method of water-resistant redispersible latex powder is as follows: dilute the emulsion with water to a solid content of 40%, weigh 85g; then mix it evenly with 13g of a 20wt% polyvinyl alcohol 0588 aqueous solution, transport it to a drying equipment for spray drying, atomize it into micro droplets by high-speed centrifugation at 15000rpm, add 6g of white carbon black anti-caking agent, and then cool and separate the rubber powder particles to obtain a water-resistant redispersible latex powder with a particle size of 80-120 mesh.

[0037] In Example 13: The preparation method of water-resistant redispersible latex powder is as follows: dilute the emulsion with water to a solid content of 40%, weigh 95g; then mix it evenly with 7g of a 20wt% polyvinyl alcohol 0588 aqueous solution, transport it to a drying equipment for spray drying, atomize it into micro droplets by high-speed centrifugation at 15000rpm, add 6g of white carbon black anti-caking agent, and then cool and separate the rubber powder particles to obtain a water-resistant redispersible latex powder with a particle size of 80-120 mesh.

[0038] The remaining process parameters in the above embodiment are the same as those in embodiment 1.

[0039] Comparative Example Comparative Example 1-2 Comparative Examples 1-2 respectively provide an emulsion and a water-resistant redispersible latex powder.

[0040] The difference between the comparative example and Example 1 is that the amount of each component used in the emulsion preparation method is different, as shown in Table 1.

[0041] The remaining process parameters in the above comparative example are the same as those in Example 1.

[0042] Comparative Examples 3-8 Comparative Examples 3-8 provide an emulsion and a water-resistant redispersible latex powder, respectively.

[0043] The differences between the above comparative example and Example 1 are specifically as follows.

[0044] In Comparative Example 3: the mixed monomer is composed of vinyl acetate, butyl acrylate and vinyl versatate in a weight ratio of 36:3:8.

[0045] In Comparative Example 4: the mixed monomer is composed of vinyl acetate, butyl acrylate, vinyl versatate, and lauryl methacrylate in a weight ratio of 40:1:9:2.

[0046] In Comparative Example 5: In the preparation method of the emulsion, an equal amount of polyvinyl alcohol 0588 is used instead of polyvinyl alcohol 1792.

[0047] In Comparative Example 6: In the preparation method of water-resistant redispersible latex powder, an equal amount of polyvinyl alcohol 1792 is used instead of polyvinyl alcohol 0588.

[0048] In Comparative Example 7: The preparation method of water-resistant redispersible latex powder is as follows: dilute the emulsion with water to a solid content of 30%, weigh 90g; then mix it evenly with 10g of a 28wt% aqueous solution of polyvinyl alcohol 0588, transport it to a drying equipment for spray drying, atomize it into micro droplets by high-speed centrifugation at 15000rpm, add 6g of white carbon black anti-caking agent, and then cool and separate the rubber powder particles to obtain a water-resistant redispersible latex powder with a particle size of 80-120 mesh.

[0049] In Comparative Example 8: The preparation method of water-resistant redispersible latex powder is as follows: dilute the emulsion with water to a solid content of 40%, weigh 100 g; then mix it evenly with 5 g of a 20wt% aqueous solution of polyvinyl alcohol 0588, transport it to a drying equipment for spray drying, atomize it into micro droplets by high-speed centrifugation at 15000 rpm, add 6 g of white carbon black anti-caking agent, and then cool and separate the rubber powder particles to obtain a water-resistant redispersible latex powder with a particle size of 80-120 mesh.

[0050] The remaining process parameters in the above comparative example are the same as those in Example 1.

[0051] Performance testing According to the standard of JC / T547-2017 "Ceramic Tile Adhesive", the tensile bonding strength performance of the obtained redispersible latex powder was tested.

[0052] After the water-resistant redispersible latex powder is immersed in water for 14 days, the tensile bonding strength is tested and the water resistance is calculated; the calculation formula is: water resistance = tensile bonding strength after immersion in water / tensile bonding strength of original sample × 100%.

[0053] Test results: as shown in Table 2.

[0054] Table 2 Performance test results of water-resistant redispersible latex powder in Examples and Comparative Examples Combined with Table 2, by comparing the test results of the embodiment and the comparative example, it can be seen that the tensile bonding strength of the redispersible latex powder obtained by using the technical solution of the present application is ≥1.39MPa, and the tensile bonding strength after the immersion test is ≥1.09MPa, which has good water resistance.

[0055] By comparing the test results of Examples 1-5 with those of Comparative Examples 1-2, it can be seen that in the process of preparing the emulsion, the amount of each raw material, especially the amount of polyvinyl alcohol 1792 and the mixed monomer has a great influence on the performance of the redispersible latex powder. The present application has optimized the amount of each raw material through multiple tests and reasonable screening, and the obtained redispersible latex powder has excellent performance.

[0056] By comparing the test results of Examples 1, 6-9 with Comparative Examples 3-4, when the composition types of the mixed monomers do not match, the performance of the prepared redispersible latex powder is poor. The present application uses a mixed monomer composed of vinyl acetate, butyl acrylate, versatate, and lauryl methacrylate in a weight ratio of 28-36:3-8:3-8:3-8 to obtain a redispersible latex powder with excellent performance.

[0057] In the preparation method of the emulsion in Comparative Example 5, polyvinyl alcohol 0588 replaced polyvinyl alcohol 1792, and in the preparation method of the water-resistant redispersible latex powder in Comparative Example 6, polyvinyl alcohol 1792 replaced polyvinyl alcohol 0588. The performance of the obtained redispersible latex powder was poor.

[0058] By comparing the test results of Examples 1, 10-13 with Comparative Examples 7-8, it can be seen that in the preparation method of water-resistant redispersible latex powder, the dosage specifications of each raw material have a great influence on the performance of the redispersible latex powder. The present application has obtained redispersible latex powder with excellent performance through multiple tests and reasonable screening of the specifications and dosages of the emulsion, polyvinyl alcohol 0588 aqueous solution, and anti-caking agent.

[0059] Although the present invention has been described in detail above with general descriptions and specific embodiments, it is obvious to those skilled in the art that some modifications or improvements may be made thereto based on the present invention. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection claimed by the present invention.

Claims

1. An emulsion for preparing a water-resistant redispersible latex powder, characterized in that: Specifically, it includes the following components in parts by weight: 380-420 parts of water, 20-30 parts of polyvinyl alcohol 1792, 2-5 parts of emulsifier NP-30, 3-5 parts of defoamer DM515, 450-490 parts of mixed monomers, and 90-120 parts of 4-8wt% ammonium persulfate aqueous solution; The mixed monomer is composed of vinyl acetate, butyl acrylate, versatate vinyl ester and lauryl methacrylate in a weight ratio of 28-36:3-8:3-8:3-8.

2. The water-resistant redispersible latex powder according to claim 1, characterized in that: The emulsion specifically includes the following components in parts by weight: 390-410 parts of water, 23-27 parts of polyvinyl alcohol 1792, 3-4 parts of emulsifier NP-30, 3.5-4.5 parts of defoamer DM515, 460-480 parts of mixed monomers, and 100-112 parts of 4-8 wt % ammonium persulfate aqueous solution.

3. The emulsion for preparing water-resistant redispersible latex powder according to claim 2, characterized in that: The emulsion specifically includes the following components in parts by weight: 400 parts of water, 25 parts of polyvinyl alcohol 1792, 3.5 parts of emulsifier NP-30, 4.5 parts of defoamer DM515, 470 parts of mixed monomers, and 106 parts of 6 wt % ammonium persulfate aqueous solution.

4. The emulsion for preparing water-resistant redispersible latex powder according to claim 1, characterized in that: The mixed monomer is composed of vinyl acetate, butyl acrylate, versatate vinyl ester and lauryl methacrylate in a weight ratio of 30-34:4-6:4-6:4-6.

5. The emulsion for preparing water-resistant redispersible latex powder according to claim 4, characterized in that: The mixed monomers are composed of a weight ratio of 31-33: 4.5-5.5:4.5-5.5:4.5-5.5 is a mixture of vinyl acetate, butyl acrylate, vinyl versatate and lauryl methacrylate.

6. The method for preparing an emulsion for preparing a water-resistant redispersible latex powder according to any one of claims 1 to 5, characterized in that: Specifically, the following steps are performed in sequence: Mix polyvinyl alcohol 1792 and water, raise the temperature to 85-95°C, until polyvinyl alcohol 1792 is completely dissolved, and then cool down to 73-78°C; Emulsifier NP-30 and defoamer DM515 were added to the reaction system, and nitrogen flow was introduced to maintain an oxygen-free environment; After 8-12 minutes, the mixed monomer and the ammonium persulfate aqueous solution are simultaneously added dropwise by using a peristaltic pump with dual-pass control, and the addition time of the mixed monomer is controlled to be maintained at 2-3 hours, and the addition time of the ammonium persulfate aqueous solution is controlled to be maintained at 3-3.5 hours; during this period, the reaction temperature is controlled at 75-95°C; during this period, the viscosity is observed and the stirring speed is dynamically adjusted; 25-45 minutes after the completion of the dropwise addition of the ammonium persulfate aqueous solution, vacuum treatment is started to remove the residual monomers and then the temperature is cooled to 5-30° C. to obtain the product.

7. A water-resistant redispersible latex powder, characterized in that: The invention comprises polyvinyl alcohol 0588, an anti-caking agent and the emulsion described in any one of claims 1 to 5.

8. The water-resistant redispersible latex powder according to claim 7, characterized in that: The anti-caking agent is selected from any one or more of white carbon black and kaolin.

9. The method for preparing the water-resistant redispersible latex powder according to any one of claims 7 to 8, characterized in that: Specifically, the following steps are performed in sequence: The emulsion is diluted with water to a solid content of 35-45%, and 85-95 parts by weight are weighed; then, it is evenly mixed with 7-13 parts by weight of a 17-23wt% aqueous solution of polyvinyl alcohol 0588, and transported to a drying device for spray drying, atomized into micro droplets by high-speed centrifugation, 4-10 parts of an anti-caking agent are added, and then the rubber powder particles are cooled and separated to obtain the water-resistant redispersible latex powder.

10. The method for preparing the water-resistant redispersible latex powder according to claim 9, characterized in that: Specifically, the following steps are performed in sequence: The emulsion is diluted with water to a solid content of 37-42%, and 87-92 parts by weight are weighed; then, it is evenly mixed with 8-12 parts by weight of an 18-21wt% aqueous solution of polyvinyl alcohol 0588, and transported to a drying device for spray drying, atomized into micro droplets by high-speed centrifugation, 5-9 parts of an anti-caking agent are added, and then the rubber powder particles are cooled and separated to obtain a water-resistant redispersible latex powder with a particle size of 80-120 meshes.

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