An early-stage water-resistant emulsion, a preparation method and application thereof

Abstract

This invention discloses an early water-resistant emulsion, comprising the following monomer components in the following weight ratios prepared by emulsion polymerization: a) 15-70%, preferably 44-66%, of ester monomers; b) 1.3-10%, preferably 2-4%, of olefinic unsaturated monomers containing acetoacetic acid groups; c) 0.5-5%, preferably 1-5%, of unsaturated monomers containing hydrophilic groups; d) 0.2-5%, preferably 0.5-2%, of reactive silane coupling agents; e) 10-50%, preferably 20-30%, of styrene; f) 14-25%, preferably 14-15%, of phosphorus-containing monomers. In exterior wall coating formulations, this emulsion provides strong early water resistance while also offering high stain resistance and high gloss.

Description

Technical Field

[0001] This invention relates to the field of coatings, specifically to an acrylic emulsion, and more particularly to an early-stage water-resistant emulsion for exterior walls, its preparation method, and its application. Background Technology

[0002] The importance of early water resistance for exterior wall coatings cannot be ignored. It directly affects the overall performance of the coating, the protective effect on the building, and its service life. Coatings with good early water resistance demonstrate strong resistance to water erosion from the initial application stage, ensuring the stability of the coating during construction and use. This stability helps the coating form a uniform coating, avoiding problems such as early cracking and peeling. Coatings with good early water resistance maintain stable performance over long-term use, reducing coating damage caused by water erosion and thus extending the coating's service life. The importance of early water resistance for exterior wall coatings is reflected in ensuring the overall performance of the coating, the effectiveness of building protection, the impact on construction quality and progress, and enhancing the value of the building. Therefore, when selecting exterior wall coatings, their water resistance should be fully considered, and products with good water resistance should be given priority.

[0003] Most common exterior wall coatings on the market require application on sunny days. To prevent water droplets from falling onto the paint film during rainy days and causing whitening or discoloration, most commercially available products cannot pass the 1-hour early water resistance test.

[0004] Patent CN116013852B introduces a method to improve early water resistance by modifying polyurethane coatings with silicon. Silicon itself has strong hydrophobicity, but the method is complicated and costly to apply to polyurethane coatings, making it difficult to promote.

[0005] Patent CN114133768B adjusts the coating formula to accelerate the drying speed, giving the coating relatively good early water resistance. However, excessively fast drying speed will lead to poor application performance and affect product use. Summary of the Invention

[0006] To overcome the shortcomings of existing technologies, this patent innovatively proposes a technical solution to significantly enhance material performance by introducing specific phosphorus-containing functional monomers, particularly achieving a breakthrough improvement in the bonding ability with powders (such as inorganic fillers, pigment particles, etc.). These carefully designed phosphorus-containing functional monomers not only possess unique chemical structures, enabling them to form strong chemical bonds or physical adsorption with powder surfaces at the molecular level, but also endow the material with a series of excellent additional properties due to the introduction of phosphorus.

[0007] Specifically, the introduction of phosphorus effectively improves the interaction between the functional monomer and the powder particle surface, promotes structural optimization of the interfacial region, reduces interfacial defects, and thus significantly enhances the bonding tightness and stability between the two. This enhanced bonding ability not only enables the coating to disperse and fix the powder more effectively during the preparation process, but also significantly improves the gloss and stain resistance of the finished product. At the same time, due to the presence of double bonds in this structure, triphenylphosphine no longer participates in the system as a small organic molecule, but rather as a functional monomer that becomes part of the polymer. Small organic molecules often lead to a decrease in emulsion stability, while the presence of functional monomers improves both stability and odor.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] An early water-resistant emulsion, comprising monomer components in the following weight ratios, prepared by emulsion polymerization:

[0010] a) 15-70%, preferably 44-66% ester monomers;

[0011] b) 1.3-10%, preferably 2-4%, of olefinic unsaturated monomers containing acetoacetic acid groups;

[0012] c) 0.5-5%, preferably 1-5%, of unsaturated monomers containing hydrophilic groups;

[0013] d) 0.2-5%, preferably 0.5-2%, of reactive silane coupling agent;

[0014] e) 10-50%, preferably 20-30% styrene;

[0015] f) 14-25%, preferably 14-15% phosphorus-containing monomers;

[0016] The total mass of components a), b), c), d), e), and f) is 100%.

[0017] In a preferred embodiment of the present invention, component a) is selected from alkyl acrylates, allyl acrylates, vinyl acetates and their methyl-substituted derivatives having 1-16 carbon atoms, preferably from alkyl acrylates, vinyl acetates and their methyl-substituted derivatives having 1-8 carbon atoms, more preferably from methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, methyl 2-methacrylate, isoamyl methacrylate, and heptyl methacrylate, or one or more of these.

[0018] Preferably, component b) is selected from one or more of ethyl acetoacetate, propoxy acetoacetate, butoxy acetoacetate, vinyl acetoacetate, allyl acetoacetate and their methyl derivatives, preferably one or two of ethyl acetoacetate and allyl acetoacetate.

[0019] Preferably, the hydrophilic group of component c) is selected from carboxyl, hydroxyl, amide, sulfonic acid, phosphate, urea, sulfonate, sulfate, and phosphate groups; preferably, component c) is one or more of acrylic acid, methacrylic acid, hydroxyethyl acrylate, acrylamide, methacrylamide, ethyl ethylene urea, vinyl alkoxy phosphate, and sodium 2-acrylamide-2-methylpropanesulfonate.

[0020] Preferably, component d) is selected from silane coupling agents containing vinyl or epoxy functional groups, preferably one or more of vinyltrimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, and mercaptopropyltrimethoxysilane.

[0021] Preferably, component f) is as shown in Formula I:

[0022]

[0023] In a preferred embodiment of the present invention, the raw materials for preparing the emulsion further include emulsifier, initiator, neutralizer, post-treatment agent, pH adjuster, and water.

[0024] In a preferred embodiment of the present invention, the emulsifier is selected from one or more of sodium dodecyl sulfate, sodium p-styrene sulfonate, sodium dodecylbenzene sulfonate, alcohol ether sulfosuccinate, alkyl alcohol ether sulfate, and alkyl alcohol ether phosphate, preferably sodium dodecyl sulfate and / or sodium dodecylbenzene sulfonate.

[0025] Preferably, the amount of the emulsifier is 1-5% of the total mass of components a)-f), more preferably 1-2%.

[0026] The initiator is selected from one or more of sodium persulfate, potassium persulfate, and ammonium persulfate, preferably sodium persulfate and / or potassium persulfate.

[0027] Preferably, the total amount of the initiator is 0.2-0.6% of the total mass of components a)-f), more preferably 0.2-0.4%.

[0028] The neutralizing agent is selected from one or more of sodium bicarbonate, diethylenetriamine, diethanolamine, and ethanolamine, with sodium bicarbonate being preferred.

[0029] Preferably, the amount of neutralizing agent is 0.1-4% of the total mass of monomer components a)-f), more preferably 0.1-0.3%.

[0030] The post-treatment agent includes an oxidizing agent and / or a reducing agent. The oxidizing agent is selected from one or more of tert-butyl hydroperoxide, hydrogen peroxide, sodium persulfate, potassium persulfate, and ammonium persulfate, preferably tert-butyl hydroperoxide and / or hydrogen peroxide. The reducing agent is selected from one or more of sodium bisulfite, sodium metabisulfite, and vitamin C, preferably sodium bisulfite and / or sodium metabisulfite.

[0031] Preferably, the total amount of the post-treatment agent is 0.15-0.6% of the total mass of components a)-f), more preferably 0.2-0.4%.

[0032] The pH adjuster is selected from one or more of diethylenetriamine, diethanolamine, and ethanolamine, preferably diethylenetriamine and / or ethanolamine;

[0033] Preferably, the endpoint of the amount of pH adjuster added is to adjust the pH of the system to 7-9.

[0034] Preferably, the total amount of water used is 1-1.5 times the total mass of components a)-f), more preferably 1-1.3 times.

[0035] Preferably, the acrylate emulsion of the present invention has a solid content of 41-45%, a pH of 7-9, and a particle size of 69-80 nm.

[0036] Another aspect of the present invention provides a method for preparing the aforementioned early water-resistant emulsion, comprising the following steps:

[0037] 1) Mix components a), b), c), d), e), f), water, and a portion of the emulsifier evenly to prepare a pre-emulsion;

[0038] 2) Divide the initiator into two parts and dissolve them in water separately to obtain the dropwise initiator and the bottom initiator;

[0039] 3) Mix the neutralizer, the remaining emulsifier, and water and add them to the reactor. Stir thoroughly and heat to 80-90℃. Add part of the pre-emulsion and stir until homogeneous. Then add all the initiator from the bottom of the reactor and react for 10-20 minutes to obtain the seed emulsion.

[0040] 4) Control the temperature inside the reactor to 80-90℃, continue to add the remaining pre-emulsion and all the added initiator to the seed emulsion, add the material over 2-4 hours, and then keep warm for 20-60 minutes.

[0041] 5) Cool the reactor to 70-80℃, gradually add the post-treatment agent to the reactor, add the agent over 2-4 hours, and then keep it at that temperature for 30-60 minutes;

[0042] 6) Cool down to below 45℃, add pH adjuster to adjust the pH of the system to 7-9, strip, filter and discharge.

[0043] In a preferred embodiment of the present invention, the amount of emulsifier used in step 1) accounts for 90-99.5% of the total mass of the emulsifier.

[0044] Preferably, the amount of water used in step 1) accounts for 25-35% of the total water mass.

[0045] In a preferred embodiment of the present invention, in step 2), the amount of initiator used to prepare the dropwise initiator accounts for 25-50% of the total mass of the initiator, and the amount of initiator used to prepare the bottom initiator accounts for 50-75% of the total mass of the initiator.

[0046] Preferably, in step 2), the amount of water used to prepare the dropwise initiator accounts for 1-6% of the total water mass, and the amount of water used to prepare the bottom initiator accounts for 1-6% of the total water mass.

[0047] Preferably, the amount of pre-emulsion used in step 3) to prepare the seed emulsion is 1-8% of the total mass of the pre-emulsion in step 1).

[0048] In a preferred embodiment of the present invention, the stripping temperature in step 6) is 55-85°C and the pressure is controlled between -75Kpa and -95Kpa.

[0049] Based on another aspect of the present invention, the application of the aforementioned early-stage water-resistant emulsion for exterior walls or the early-stage water-resistant emulsion for exterior walls prepared by the method is also provided in coatings.

[0050] The beneficial effects of this invention are as follows:

[0051] The acrylic emulsion of this invention has good film-forming effect without the addition of film-forming aids, as well as advantages such as low MFFT (minimum film-forming temperature), low VOC content, and good environmental performance, making it particularly suitable for use in the field of building interior wall coatings.

[0052] The acrylic emulsion provided by this invention is an aqueous emulsion with low VOC, is safe and environmentally friendly, has excellent early water resistance, and has a simple preparation process. Detailed Implementation

[0053] The present invention will be further illustrated below with specific embodiments. These embodiments are merely illustrative and do not limit the scope of the invention.

[0054] The raw materials used in the following embodiments are shown in Table 1. Unless otherwise specified, all other raw materials are common commercially available materials:

[0055] Table 1 Raw Material Information

[0056]

[0057]

[0058] Early water resistance performance: The sample paint was mixed to a blue color (98g white paint + 2g titanium blue paste).

[0059] Using a 15*7 cement pressure board, apply a 100um thick paint film to prepare 3 samples. Dry at room temperature. After 3 hours, immerse half of the sample in room temperature water. Test the water whitening recovery at 1 day, 3 days, 7 days, and 1 day at room temperature.

[0060] 5 points: It did not turn white.

[0061] 4 points: Slightly whitened

[0062] 3 points: Noticeably whitened, but acceptable.

[0063] 2 points: Noticeably whitened, unacceptable.

[0064] 1 point: Abnormal conditions such as bulging occur.

[0065] 0 points: Paint film damaged.

[0066] Other performance parameters were tested according to GB / T 9755-2014 "Synthetic Resin Emulsion Exterior Wall Coatings".

[0067]

Example 1

[0068] Prepare the ingredients according to the following formula:

[0069] a) 609g of BA

[0070] b) 38g of AAEM

[0071] c) 14g of AA

[0072] d) 5g of A171

[0073] e) 167g styrene

[0074] f) 167g vinyltriphenylphosphine.

[0075] Prepare the following: emulsifier SDS 9.19g, SSS 9g, initiator APS 3g, neutralizer sodium bicarbonate 2g, post-treatment agent (t-BHP 2g and 5wt% sodium bisulfite aqueous solution 40g), water 1323g, and pH adjuster diethylenetriamine.

[0076] Acrylic emulsions were prepared according to the following method:

[0077] 1) Mix components a), b), c), d), e), f) with 433g water, 9g emulsifier SDS and 9g emulsifier SSS evenly to prepare a pre-emulsion;

[0078] 2) Mix 1g of initiator APS with 38g of water thoroughly to obtain the dropwise initiator; mix 2g of initiator APS with 21g of water thoroughly to obtain the bottom initiator;

[0079] 3) Mix 2g sodium bicarbonate, 0.19g emulsifier SDS and 831g water and add them to the reaction vessel. Stir thoroughly and heat to 85℃. Add 50g pre-emulsion and stir until uniform. Then add all the bottom initiator and react for 10 minutes to obtain seed emulsion.

[0080] 4) Control the temperature inside the reactor to 85℃, and continue to add the remaining pre-emulsion and all the added initiator to the seed emulsion at the same time. The total adding time is 4 hours, and then keep warm for 2 minutes.

[0081] 5) Cool the reactor to 75°C, and gradually add the post-treatment agent (2g of t-BHP and 40g of 5wt% sodium bisulfite aqueous solution) into the reactor over a period of 2 hours, and then keep it warm for 30 minutes.

[0082] 6) Cool down to below 45℃, add diethylenetriamine as a pH adjuster to adjust the pH of the system to 8, filter through a 100-mesh filter, and discharge.

[0083]

Examples 2-8

[0084] Acrylic emulsions were prepared using essentially the same method as in Example 1, with the only difference being the selection and amount of raw materials in Table 2; meanwhile, in step 3), the amount of pre-emulsion added was always 5% of its total mass.

[0085] Table 2. Raw material selection and dosage in Examples 1-8 (unit: g)

[0086]

[0087]

[0088] Comparative Example 1

[0089] The acrylic emulsion was prepared using essentially the same method as in Example 1, except that component f was not added.

[0090] Comparative Example 2

[0091] An acrylic emulsion was prepared using essentially the same method as in Example 1, except that component f was replaced with the same mass of triphenylphosphine.

[0092] The preparation method of the coating includes the following steps:

[0093] 1. Add 180g of water to a container and disperse it using a disperser;

[0094] 2. Add 2.5g of 250HBR to 180g of water with a stirring rod, then add 2g of SN154, 3g of LCN407, and 5g of 4240 dispersant;

[0095] 3. Slowly add 0.5g of AMP95 to the system. After the viscosity of the system increases, add 200g of R996, adjust the speed of the disperser to 1500r / min, and disperse for 30min.

[0096] 4. Adjust the rotation speed to 700 r / min, add 100 g of cooling water, 450 g of acrylic emulsion from the examples and comparative examples, 20 g of Texanol, and 8 g of PG;

[0097] 5. Mix 5g of U300E with 5g of water, add it to the system, disperse for 10 minutes, then add 4g of bactericide and 15g of water.

[0098] The performance test results of the coatings obtained in the examples are shown in Table 3.

[0099] Table 3 shows the performance test results of the coatings obtained from the emulsions in the examples.

[0100]

[0101] The performance of the coatings in Comparative Examples 1-3 is shown in Table 4.

[0102] Table 4. Performance of Coatings in Comparative Examples 1-3

[0103] Comparative Application Example 1 Comparative Application Example 2 State in paint container No clumps No clumps Coating properties good good Outdoor aging resistant No color change No color change Gloss level (20° / 60° / 85°) 9.7 / 11.2 / 33.0 5.1 / 19.9 / 26.0 Early water resistance 2 2 Alkali resistance white white

Claims

1. An early water-resistant emulsion, comprising monomer components in the following weight ratios prepared by emulsion polymerization: a) 15-70%, preferably 44-66% ester monomers; b) 1.3-10%, preferably 2-4%, of olefinic unsaturated monomers containing acetoacetic acid groups; c) 0.5-5%, preferably 1-5%, of unsaturated monomers containing hydrophilic groups; d) 0.2-5%, preferably 0.5-2%, of reactive silane coupling agent; e) 10-50%, preferably 20-30% styrene; f) 14-25%, preferably 14-15% phosphorus-containing monomers; in, The total mass of components a), b), c), d), e), and f) is 100%.

2. The early-stage water-resistant emulsion as described in claim 1, characterized in that, Component a) is selected from alkyl acrylates, allyl acrylates, vinyl acetates and their methyl-substituted derivatives having 1-16 carbon atoms, preferably from alkyl acrylates, vinyl acetates and their methyl-substituted derivatives having 1-8 carbon atoms, more preferably from methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, isooctyl acrylate, methyl 2-methacrylate, isopentyl methacrylate, and heptyl methacrylate; and / or, component b) is selected from ethyl acetoacetate, propoxy acetoacetate, butoxy acetoacetate, vinyl acetoacetate, allyl acetoacetate and their methyl-substituted derivatives, preferably from ethyl acetoacetate and allyl acetoacetate, or both.

3. The early water-resistant emulsion as described in claim 1 or 2, characterized in that, The hydrophilic group of component c) is selected from carboxyl, hydroxyl, amide, sulfonic acid, phosphate, urea, sulfonate, sulfate, and phosphate groups; preferably, component c) is selected from one or more of acrylic acid, methacrylic acid, hydroxyethyl acrylate, acrylamide, methacrylamide, ethyl ethylene urea, vinyl alkoxy phosphate, and sodium 2-acrylamido-2-methylpropanesulfonate; and / or, component d) is selected from silane coupling agents containing vinyl or epoxy functional groups, preferably one or more of vinyltrimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, and mercaptopropyltrimethoxysilane.

4. The early-stage water-resistant emulsion as described in any one of claims 1-3, characterized in that, Component f) is shown in Equation I: And / or, the raw materials for preparing the emulsion may also include emulsifiers, initiators, neutralizers, post-treatment agents, pH adjusters, and water.

5. The method for preparing the early water-resistant emulsion according to any one of claims 1-4, characterized in that, Includes the following steps: 1) Mix components a), b), c), d), e), f), water, and a portion of the emulsifier evenly to prepare a pre-emulsion; 2) Divide the initiator into two parts and dissolve them in water separately to obtain the dropwise initiator and the bottom initiator; 3) Mix the neutralizer, the remaining emulsifier, and water and add them to the reactor. Stir thoroughly and heat to 80-90℃. Add part of the pre-emulsion and stir until homogeneous. Then add all the initiator from the bottom of the reactor and react for 10-20 minutes to obtain the seed emulsion. 4) Control the temperature inside the reactor to 80-90℃, continue to add the remaining pre-emulsion and all the added initiator to the seed emulsion, add the material over 2-4 hours, and then keep warm for 20-60 minutes. 5) Cool the reactor to 70-80℃, gradually add the post-treatment agent to the reactor, add the agent over 2-4 hours, and then keep it at that temperature for 30-60 minutes; 6) Cool down to below 45℃, add pH adjuster to adjust the pH of the system to 7-9, strip, filter and discharge.

6. The preparation method according to claim 5, characterized in that, In step 1), the amount of emulsifier used accounts for 90-99.5% of the total emulsifier mass; and / or, in step 1), the amount of water used accounts for 25-35% of the total water mass.

7. The preparation method according to claim 5 or 6, characterized in that, In step 2), the amount of initiator used to prepare the dropwise initiator accounts for 25-50% of the total mass of the initiator, and the amount of initiator used to prepare the bottom initiator accounts for 50-75% of the total mass of the initiator.

8. The preparation method according to any one of claims 5-7, characterized in that, In step 2), the amount of water used to prepare the drop initiator is 1-6% of the total water mass, and the amount of water used to prepare the bottom initiator is 1-6% of the total water mass; and / or, in step 3), the amount of pre-emulsion used to prepare the seed emulsion is 1-8% of the total mass of the pre-emulsion in step 1); and / or, in step 6), the stripping temperature is 55-85℃, and the pressure is controlled between -75Kpa and -95Kpa.

9. The application of the early water-resistant emulsion as described in any one of claims 1-4 or the early water-resistant emulsion prepared by the preparation method as described in any one of claims 5-8 in coatings.

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