A matt high-stain-resistant hydrophobic polyacrylate emulsion coating layer and a preparation method and application thereof

Abstract

The application discloses a kind of matte high stain-resistant hydrophobic polyacrylate emulsion coating and its preparation method and application;The matte high stain-resistant hydrophobic polyacrylate emulsion coating is obtained by coating polyacrylate core-shell emulsion on the surface of substrate and then heating to form film, the film-forming temperature is controlled to be lower than the glass transition temperature of core layer polymer and higher than the glass transition temperature of shell layer polymer, and the film-forming temperature is controlled to be 0-5℃ higher or lower than the average value of core layer glass transition temperature and shell layer glass transition temperature;The glass transition temperature of core layer polymer is controlled to be 45-95℃, and the glass transition temperature of shell layer polymer is 10-60℃;The glass transition temperature difference between core layer polymer and shell layer polymer is controlled to be 35-60℃.A kind of matte high stain-resistant hydrophobic polyacrylate emulsion coating is provided, which has a coating hardness of 3H, the coating can achieve matte, low VOC, high stain resistance, good water resistance, and the adhesion is all 0 grade.

Description

Technical Field

[0001] This invention relates to the field of water-based coatings, and in particular to a matte, highly stain-resistant, hydrophobic polyacrylate emulsion coating, its preparation method, and its application, belonging to the technical field of hydrophobic and stain-resistant coatings. Background Technology

[0002] With global economic and technological development, energy consumption and environmental pollution have become major global concerns. Industrial development, industrial waste gas, and vehicle exhaust have led to smog becoming a common phenomenon in many cities, resulting in narrowed visibility and buildings becoming dirty without proper cleaning. Hydrophobic polyacrylate emulsion coatings, used in architectural coatings or for outdoor equipment in harsh climates and environments, offer excellent stain resistance. They are also effective waterproofing and stain-resistant materials for textiles and leather. However, existing hydrophobic polyacrylate emulsion coatings achieve their hydrophobic effect through methods such as using silicone-fluorine modified emulsions or adding hydrophobic additives and nanoparticles to increase coating roughness. Neither of these methods guarantees long-term hydrophobicity, and the hydrophobic effect is not ideal.

[0003] Furthermore, existing coatings often cannot simultaneously achieve a matte finish and stain resistance, limiting their applications. For example, the invention "A Pure Acrylic Emulsion for Matte Topcoat Varnish and Its Preparation Method and Application" (application date: August 16, 2022, application number: 202210978463.X, publication number: CN115232243A) chooses not to add conventional matting agents such as matting powder and paraffin, but instead adds organosilicon-modified polymers, fumed silica slurry, and polymer-modified nano-silica to achieve a matte effect. However, the latter two are blended with the emulsion, and over time, harsh weather conditions such as rain can cause the coating performance to decline. In addition, the emulsion contains silane coupling agents, which can cause microphase separation in the coating as its service life increases, making it impossible to guarantee the long-term performance of the coating. The invention "A Method for Preparing a Hydrophobic Acrylic Coating", with application date: August 18, 2022, application number: 202210991113.7, and publication number: CN116023691A, first modifies nano-silica with fluorosilicone, then prepares a silica / acrylic emulsion, and finally obtains a polyacrylate coating with a maximum contact angle of 111.5°. The invention also compared it with nanoparticles without fluorosilicone modification, where the contact angle can only reach 97.9°, which limits the range of applications. In addition, fluorosilicone is prone to migration, causing microphase separation on the coating surface, which cannot guarantee the long-term performance of the coating. Summary of the Invention

[0004] This invention addresses the problems existing in the prior art by providing a matte, highly stain-resistant, hydrophobic polyacrylate emulsion coating with a film hardness of 3H, achieving a matte finish, low VOC, high stain resistance, good water resistance, and adhesion grade of 0, as well as a method for its preparation.

[0005] Another object of the present invention is to provide the application of the matte, highly stain-resistant, hydrophobic polyacrylate emulsion coating in the preparation of inkjet inks, matte coatings, and stain-resistant coatings.

[0006] This invention is achieved through the following technical solution:

[0007] A matte, highly stain-resistant, hydrophobic polyacrylate emulsion coating is obtained by coating a polyacrylate core-shell emulsion onto a substrate surface and then heating it to form a film. The film-forming temperature is controlled to be lower than the glass transition temperature of the core polymer and higher than the glass transition temperature of the shell polymer, while the film-forming temperature is controlled to be 0-5°C higher or lower than the average of the glass transition temperatures of the core and shell polymers. The polyacrylate core-shell emulsion is obtained by adding a shell pre-emulsion and a first initiator dissolved in deionized water to the core polymer emulsion, polymerizing it at 80-82°C, coating the shell polymer onto the core polymer, holding the reaction at 85-90°C for 1-1.5 hours, and then adjusting the pH. The glass transition temperature of the core polymer is 45-95°C, and the glass transition temperature of the shell polymer is 10-60°C. The difference between the glass transition temperatures of the core polymer and the shell polymer is controlled to be 35°C-60°C.

[0008] To further achieve the objective of this invention, preferably, the preparation of the core polymer emulsion is as follows: 5%–8% of the mass of pre-emulsion A is added to the seed monomer solution. After the temperature rises to the initiation temperature of 74–78°C, a second initiator dissolved in deionized water is added. When the temperature rises to 80–82°C, pre-emulsion C is simultaneously added to pre-emulsion B, pre-emulsion B is added to the remaining pre-emulsion A, and the remaining pre-emulsion A is added to the seed monomer solution. The rate at which pre-emulsion B is added to the remaining pre-emulsion A is 3–6 times that of the remaining pre-emulsion A added to the seed monomer solution, and the rate at which pre-emulsion C is added to pre-emulsion B is 3–6 times that of pre-emulsion B added to the remaining pre-emulsion A. Simultaneously, a third initiator is added to the seed monomer solution, and the reaction is carried out at 80–82°C for 1–2 hours.

[0009] Preferably, the seed monomer solution is obtained by stirring and dispersing a first surfactant and a first deionized water, then adding a pH buffer and a first reactive monomer; the first reactive monomer is one or more of acrylamide, N-hydroxymethylacrylamide, and acrylic acid.

[0010] The pre-emulsion A is composed of a second surfactant, a second deionized water, and a second reactive monomer, wherein the second reactive monomer is one or more of methacrylic acid, hydroxyethyl methacrylate, hydroxypropyl acrylate, and ethyl methacrylate.

[0011] The pre-emulsion B is composed of a third surfactant, a third deionized water, and a third reactive monomer. The third reactive monomer is composed of a first hard monomer and a crosslinking monomer. The first hard monomer is one or more of methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobornyl methacrylate, tert-butyl methacrylate, and cyclohexyl methacrylate. The crosslinking monomer is one of allyl methacrylate, divinylbenzene, and diacetone acrylamide-adipamide.

[0012] The pre-emulsion C is composed of a fourth surfactant, a fourth deionized water and a fourth reactive monomer. The fourth reactive monomer is a first soft monomer, which is one or more of butyl acrylate, lauryl methacrylate and isooctyl acrylate.

[0013] The shell preemulsion D is composed of a fifth surfactant, a fifth deionized water, and a fifth reactive monomer; the fifth reactive monomer comprises a second hard monomer and a crosslinking monomer; the second hard monomer is one or more of tert-butyl acrylate, methyl methacrylate, cyclohexyl methacrylate, and isobornyl methacrylate; the crosslinking monomer is one of allyl methacrylate, divinylbenzene, and diacetone acrylamide-adipic acid hydrazide; in the shell preemulsion, by mass percentage, the fifth surfactant accounts for 0.8% to 1.4%, the fifth deionized water accounts for 43.6% to 54.2%, and the fifth reactive monomer accounts for 45% to 55%;

[0014] Preferably, the first surfactant and the second surfactant are one of a reactive surfactant and an anionic surfactant, wherein the reactive surfactant is SR-10 surfactant; and the anionic surfactant is one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, and sodium alkyl-acrylic acid-2-ethanesulfonate.

[0015] The third, fourth, and fifth surfactants are one of reactive surfactants, anionic surfactants, and nonionic surfactants; the reactive surfactant is SR-10 surfactant; the anionic surfactant is one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, and sodium alkyl-acrylic acid-2-ethanesulfonate; the nonionic surfactant is a secondary alcohol polyoxyethylene ether nonionic surfactant.

[0016] The fifth reactive monomer also includes a second soft monomer, which is one of butyl acrylate and lauryl methacrylate.

[0017] Preferably, the first, second, and third initiators are one of redox initiators, persulfate initiators, or oil-soluble initiators; and the pH buffer is sodium bicarbonate and / or sodium carbonate.

[0018] Preferably, the redox initiator is one of a persulfate-thiol redox system and a TBHP-ascorbic acid redox system; the persulfate initiator is one of ammonium persulfate, potassium persulfate, and sodium persulfate; and the oil-soluble initiator is one of AIBA and AIBN.

[0019] Preferably, the addition of a shell pre-emulsion and a first initiator dissolved in deionized water to the core polymer emulsion comprises, by mass percentage, 45.9–47.45% core polymer emulsion, 45.9–47.45% shell pre-emulsion, 5%–8% deionized water, and 0.1%–0.2% first initiator; the pH adjustment is achieved by adding ammonia.

[0020] Preferably, in the preparation of the core polymer emulsion, the seed monomer solution accounts for 8-10% by mass percentage, pre-emulsion A accounts for 16-25%, pre-emulsion B accounts for 35%-60%, and pre-emulsion C accounts for 16%-30%.

[0021] In the seed monomer solution, by mass percentage (8-10%), the first surfactant accounts for 0.005%-0.02%, the first deionized water accounts for 5.99%-6.97%, the pH buffer accounts for 0.005%-0.01%, and the first type of reactive monomer accounts for 2-3%.

[0022] In the pre-emulsion A, the second surfactant accounts for 0.02% to 0.04% by mass, the second deionized water accounts for 10.98% to 16.96%, and the second reactive monomer accounts for 5% to 8% by mass.

[0023] In the pre-emulsion B, based on a mass percentage of 35% to 60%, the third surfactant is 0.06% to 0.08%, the third deionized water is 14.94% to 29.92%, and the third reactive monomer is 20% to 30%.

[0024] In the pre-emulsion C, by mass percentage (16%–30%), there are 0.02%–0.03% of the fourth surfactant, 7.98%–15.97% of the fourth deionized water, and 8%–14% of the fourth reactive monomer.

[0025] The method for preparing the matte, highly stain-resistant, hydrophobic polyacrylate emulsion coating includes the following steps:

[0026] 1) Preparation of polyacrylate core-shell emulsion: A shell pre-emulsion and a first initiator dissolved in deionized water are added to the core polymer emulsion. After polymerization at 80-82℃, the shell polymer is coated on the core polymer. The reaction is then maintained at 85-90℃ for 1-1.5h. The glass transition temperature of the core polymer is controlled at 45-95℃, and the glass transition temperature of the shell polymer is controlled at 10-60℃. The glass transition temperatures of the core polymer and the shell polymer are controlled at 35℃-60℃.

[0027] 2) Preparation of matte, highly stain-resistant, hydrophobic polyacrylate emulsion coating: The coating is obtained by coating a polyacrylate core-shell emulsion onto the surface of a substrate and then heating it to form a film. The film-forming temperature is controlled to be lower than the glass transition temperature of the core polymer and higher than the glass transition temperature of the shell polymer, and the film-forming temperature is controlled to be 0-5°C higher or lower than the average of the glass transition temperatures of the core and shell polymers.

[0028] The matte, highly stain-resistant, hydrophobic polyacrylate emulsion coating described herein is used in the preparation of inkjet ink coatings, matte coatings, and stain-resistant coatings. The matte, highly stain-resistant, hydrophobic polyacrylate emulsion coating of this invention can improve the storage stability and long-term performance of inkjet inks, exhibits excellent flowability without clogging problems, and enhances pencil hardness, adhesion, water resistance, and abrasion resistance, while also expanding the ink contact angle range. This matte, highly stain-resistant, hydrophobic polyacrylate emulsion coating of the present invention has a matte finish and a fine appearance, making it suitable for stain-resistant coatings used in outdoor construction and equipment. It exhibits excellent overall performance, is adaptable to various outdoor environments, and maintains long-term stable performance.

[0029] Compared with existing polyacrylate emulsions, the advantages of this invention are:

[0030] 1. The emulsion prepared in this invention, without the addition of any nanoparticles for modification, controls the glass transition temperature of the core and shell layers by adjusting the amount of soft and hard monomers added. The core layer glass transition temperature is maintained at 45–95°C, and the shell layer glass transition temperature at 10–60°C. The difference in glass transition temperature between the core and shell layers is controlled within 35°C–60°C, with the core layer glass transition temperature being higher than the shell layer glass transition temperature. The film-forming process of the latex particles is controlled so that the film-forming temperature is lower than the glass transition temperature of the core polymer but higher than the glass transition temperature of the shell polymer. Simultaneously, the film-forming temperature is controlled to be 0–5°C higher or lower than the average of the core and shell glass transition temperatures. This results in a uniform, consistent protrusion on the coating surface, creating a matte, hydrophobic structure. The shell layer fuses, while the core layer does not, resulting in a uniform and stable protrusion on the coating surface. This improves the coating's roughness, increases the contact angle, and enhances its stain resistance. The highest contact angle of the coating reaches 122.73°, expanding its application areas.

[0031] 2. This invention does not add organosilicon or organofluorine for modification, but introduces hydrophobic groups from the main chain to ensure the long-term hydrophobicity of the coating and avoid the formation of microphase separation due to organosilicon and fluorine over time, which would lead to hydrophilic and hydrophobic polarization.

[0032] 3. The solvent of this invention is water, which is a low-VOC emulsion and does not contain any volatile solvents; the raw material cost is low and the process is simple.

[0033] 4. The emulsion prepared by this invention does not contain any additives. Due to the uniform and stable protrusions on the surface, the light is refracted differently on the coating surface, and the coating film has a matte finish with a gloss level of 16 to 19.8. Moreover, the protrusions have low surface energy, so contaminants cannot adhere to them, achieving both stain resistance and a matte finish.

[0034] 5. The matte, highly stain-resistant, hydrophobic polyacrylate emulsion coating prepared by this invention exhibits excellent stain resistance, water resistance, water whitening resistance, and mechanical properties; after being soaked in water for seven days, the coating shows no signs of damage and its adhesion remains at grade 0. It also maintains excellent stain resistance after six months. Attached Figure Description

[0035] Figure 1 This is a SEM image of the coating obtained under a scanning electron microscope at 500x magnification in Example 1 of the present invention.

[0036] Figure 2 This is a schematic SEM image of the coating protrusions obtained in Example 1 under a scanning electron microscope at 20kx magnification.

[0037] Figure 3 This is a diagram showing the effect of the matte coating obtained in Example 1 of the present invention.

[0038] Figure 4 , Figure 5 and Figure 6 The images shown are TEM images of the core-shell emulsion obtained under transmission electron microscopy at magnifications of 30K, 40K, and 20K, respectively, in Example 1 of this invention.

[0039] Figure 7 This is a diagram showing the stain resistance effect of the emulsion coating obtained in Example 1 of the present invention. Detailed Implementation

[0040] To gain a deeper understanding of the present invention, it will be further described below with reference to the accompanying drawings and embodiments, but the embodiments of the present invention are not limited thereto.

[0041] Existing technologies have not yet discovered a way to control film morphology and improve film performance by controlling the film-forming temperature of core-shell polymer emulsions. Due to the difficulty in controlling the actual film-forming temperature and the polymer's glass transition temperature, the film is prone to cracking or poor performance. Different degrees of core-shell fusion also lead to differences in various aspects of film performance. If the emulsion has problems with film formation, the mechanical properties and water resistance of the film will deteriorate. However, this invention limits the difference in glass transition temperatures between the core and shell layers and controls the film-forming process to achieve shell fusion while preventing core fusion, forming a natural micro-nano structure. The film can achieve the mechanical properties and water resistance of fully formed films, and also achieves high stain resistance and long-lasting hydrophobicity.

[0042] This invention introduces hydrophobic monomers into the shell layer of latex particles and adjusts the amount of soft and hard monomers added to the core and shell layers to ensure that the amount of hydrophobic monomers added to the shell layer accounts for 40% to 50% of the total monomer addition; the glass transition temperature of the shell layer is 45 to 95°C, the glass transition temperature of the core layer is 10 to 60°C, the difference in glass transition temperature between the core layer and the shell layer is controlled within 35°C to 60°C, and the glass transition temperature of the core layer is higher than that of the shell layer; the film-forming process of the latex particles is controlled so that the film-forming temperature is lower than the glass transition temperature of the core layer polymer but higher than the glass transition temperature of the shell layer polymer, and the film-forming temperature is controlled to be 0 to 5°C higher or lower than the average of the glass transition temperatures of the core layer and the shell layer, so that a uniform and consistent protrusion is formed on the coating surface to obtain a matte hydrophobic structure. Through the above control, during film formation, the shell layer of latex particles reaches a very low film-forming temperature in the microscopic state, resulting in fusion, while the core layer does not reach the minimum film-forming temperature and does not fuse. This leads to the formation of uniform and stable protrusions on the coating surface in the macroscopic state, which increases the roughness of the coating, increases the contact angle, improves the stain resistance, and at the same time, the surface is matte.

[0043] The method for preparing a matte, highly stain-resistant, hydrophobic polyacrylate emulsion according to the present invention can be achieved through the following steps:

[0044] A. Core layer raw materials: The core layer is prepared by adding four monomers dropwise, and the final core layer copolymer has a glass transition temperature of 45-95℃.

[0045] A first surfactant and a first deionized water are added to the reaction apparatus, and after stirring and dispersing, a pH buffer and a first reaction monomer are added. The first reaction monomer includes one or more of acrylamide, N-hydroxymethylacrylamide, and acrylic acid.

[0046] Pre-emulsion A is added to the first raw material tank. Pre-emulsion A consists of a second surfactant, a second deionized water, and a second reactive monomer. The second reactive monomer includes one or more of methacrylic acid, hydroxyethyl methacrylate, hydroxypropyl acrylate, and ethyl methacrylate.

[0047] Add pre-emulsion B to the second raw material tank. Pre-emulsion B includes a third surfactant, a third deionized water, and a third type of reactive monomer. The third type of reactive monomer includes one or more of the following: hard monomers: methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobornyl methacrylate, tert-butyl methacrylate, and cyclohexyl methacrylate; and crosslinking monomers: allyl methacrylate, divinylbenzene, and diacetone acrylamide-adipic acid hydrazide.

[0048] Add preemulsion C to the third raw material tank. Preemulsion C includes a fourth surfactant and a fourth deionized water, a fourth type of reaction monomer, and one or more of the soft monomers butyl acrylate, lauryl methacrylate, and isooctyl acrylate, and one of the crosslinking monomers allyl methacrylate, divinylbenzene, and diacetone acrylamide-adiazine.

[0049] B. Shell material: The shell is a single-time monomer drop-added process, and the final glass transition temperature of the shell copolymer is between 10 and 60°C.

[0050] Add pre-emulsion D to the fourth raw material tank. Pre-emulsion D includes a fifth surfactant and a fifth deionized water weighed according to a preset ratio, a fifth type of reactive monomer, and the fifth type of reactive monomer includes one or two of the following: hard monomer tert-butyl acrylate and methyl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate, butyl acrylate, lauryl methacrylate, and crosslinking monomer allyl methacrylate, divinylbenzene, and diacetone acrylamide-adiazine.

[0051] C. Preparation of core-shell emulsion: Add pre-emulsion B to pre-emulsion A; add pre-emulsion C to pre-emulsion B; add shell material to seed monomer. Add the sixth deionized water to the second initiator, and the seventh deionized water to the third initiator. After thorough dissolution, connect them to the reaction apparatus respectively.

[0052] Add pre-emulsion A to the reaction apparatus. After the temperature rises to the polymerization temperature, dissolve the first initiator in the fifth deionized water and add it to carry out seed emulsion polymerization.

[0053] Once the temperature reaches the reaction temperature, pre-emulsion A from the first raw material tank is added dropwise to the reaction apparatus at a preset dropping rate. Pre-emulsion B from the second raw material tank is then added dropwise to the first raw material tank, followed by pre-emulsion C from the third raw material tank. The dropping rate of pre-emulsion B is controlled to be five times that of pre-emulsion A, and the dropping rate of pre-emulsion C is five times that of pre-emulsion B. Simultaneously, the second initiator is added dropwise at a preset dropping rate. After the polymerization reaction, the mixture is kept at this temperature to obtain the core-layer polymer.

[0054] The pre-emulsion D from the fourth raw material tank is introduced into the reaction apparatus at a preset dropping rate, while the third initiator is added dropwise. After the polymerization reaction, the mixture is kept at a constant temperature, and the pH is adjusted to 7-8 with ammonia water to obtain a polyacrylate core-shell emulsion.

[0055] D. Core-shell emulsion film formation: The film formation temperature is set to be lower than the core glass transition temperature and higher than the shell glass transition temperature according to the preset core-shell glass transition temperature. Specifically, the average value of the core glass transition temperature and the shell glass transition temperature fluctuates by 0 to 5°C.

[0056] Example 1

[0057] Preparation of core polymer emulsion:

[0058] Add 0.036 g of sodium dodecyl sulfate (SLS) surfactant, 25.2 g of deionized water, and 0.036 g of sodium bicarbonate pH buffer to the reaction apparatus. After stirring and dispersing at 220 rpm for 10 min, add 0.36 g of acrylamide. Add pre-emulsion A to the first raw material tank. Pre-emulsion A consists of 0.072 g of sodium dodecyl sulfate surfactant, 8.4 g of deionized water, and 0.36 g of methacrylic acid. Add pre-emulsion B to the second raw material tank. Pre-emulsion B consists of 0.048 g of sodium dodecyl sulfate surfactant, 0.024 g of secondary alcohol polyoxyethylene ether, and 0.036 g of deionized water. The mixture consists of 8.4g of deionized water, 16.52g of methyl methacrylate, and 0.18g of allyl methacrylate. In the third raw material tank, pre-emulsion C is added, which consists of 0.048g of sodium dodecyl sulfate surfactant, 0.024g of secondary alcohol polyoxyethylene ether, 8.4g of deionized water, and 0.76g of butyl acrylate. In the fourth raw material tank, pre-emulsion D is added, which consists of 0.072g of sodium dodecyl sulfate, 0.036g of secondary alcohol polyoxyethylene ether, 16.8g of deionized water, 18g of tert-butyl acrylate, and 0.18g of allyl methacrylate.

[0059] Connect the second raw material tank to the first raw material tank; connect the third raw material tank to the second raw material tank; connect the fourth raw material tank to the reaction apparatus. Dissolve 0.108g of ammonium persulfate in 8.4g of deionized water, and dissolve 0.144g of ammonium persulfate in another 8.4g of deionized water. After thorough dissolution, connect them to the reaction apparatus respectively.

[0060] Add 10 wt% preemulsion A to the reaction apparatus. After the temperature rises to the polymerization temperature of 76°C, add 0.036 g of ammonium persulfate dissolved in 8.4 g of deionized water to the reaction apparatus for seed emulsion polymerization. After the temperature rises to 80°C, add preemulsion A dropwise over 1.5 h. Add preemulsion B from the second raw material tank dropwise to the first raw material tank, completing the addition over 0.3 h. Add preemulsion C from the third raw material tank dropwise to the second raw material tank, completing the addition over 0.06 h. Simultaneously, add 0.108 g of ammonium persulfate dissolved in 8.4 g of deionized water dropwise over 1.5 h. After the polymerization reaction, the core polymer is obtained.

[0061] Preparation of core-shell polymer emulsions:

[0062] The pre-emulsion D from the fourth raw material tank was introduced into the reaction apparatus and added dropwise over 2 hours. Simultaneously, 0.144 g of ammonium persulfate dissolved in 8.4 g of deionized water was added dropwise. After the polymerization reaction, the mixture was kept at 90 °C for 1 hour, and the pH was adjusted to 7-8 with ammonia water to obtain a polyacrylate core-shell emulsion.

[0063] A polyacrylate core-shell emulsion was coated onto a glass substrate using a four-sided coating tool to form a 90-micron thick wet film, which was then dried in an oven at 60°C.

[0064] The obtained polyacrylate core-shell emulsion was subjected to DSC testing, and the Tg of the core polymer was 95°C, the Tg of the shell polymer was 35°C, and the glass transition temperature difference between the core and shell was 60°C. The average Tg of the core and shell was 65°C. In this invention, the film-forming temperature is selected in the range of 60 to 65°C. In this embodiment, a film-forming temperature of 60°C is selected.

[0065] like Figure 1 and Figure 2 As shown, the coating surface has uniform protrusions in the same direction. This is because the glass transition temperature and shell thickness of the core-shell structure are different, resulting in differences in the degree of fusion between latex particles in the microscopic state during film formation. In the macroscopic state, the coating surface forms uniform and stable protrusions, which improves the roughness of the coating.

[0066] Figure 3 This is an image showing the matte coating effect obtained in Example 1 of the present invention. The protrusions on the coating surface are stable and uniform, and the different refractions of visible light on the coating surface result in the matte finish of the coating.

[0067] Figure 4-6 The image shows a TEM image of the core-shell emulsion obtained in Example 1 of this invention. As can be seen from the image, there is a distinct core-shell structure.

[0068] Figure 7The image shows the stain resistance of the emulsion coating obtained in Example 1 of this invention. Comparing the stain resistance of the glass substrate and the blank group emulsion (i.e., a non-core-shell polyacrylate emulsion prepared by conventional emulsion polymerization without the addition of tert-butyl acrylate) coating, it can be seen that the emulsion coating obtained in Example 1 has excellent stain resistance. This is because the surface energy of the coating surface is low, and contaminants cannot adhere to it.

[0069] The SEM images of the coating, the matte coating effect image, the TEM image of the core-shell structure emulsion, and the stain resistance effect image of the emulsion coating in the following embodiments are similar to those in Embodiment 1, and are not provided one by one.

[0070] Example 2: Within the glass transition temperature design range of this invention, the core layer Tg = 95℃, the shell layer Tg = 60℃, and the core-shell glass transition temperature difference is 35℃; the surfactant is 1%, and drying is performed in an oven at 72.5℃.

[0071] Preparation of core polymer emulsion:

[0072] Add 0.036 g of sodium dodecylbenzenesulfonate, 25.2 g of deionized water, and 0.036 g of sodium carbonate as a pH buffer to the reaction apparatus. After stirring and dispersing at 220 rpm for 10 min, add 0.36 g of acrylamide. Add pre-emulsion A to the first raw material tank. Pre-emulsion A consists of 0.072 g of sodium dodecylbenzenesulfonate, 8.4 g of deionized water, and 0.36 g of methacrylic acid. Add pre-emulsion B to the second raw material tank. Pre-emulsion B consists of 0.048 g of sodium dodecylbenzenesulfonate, 0.024 g of secondary alcohol polyoxyethylene ether, and 8 g of deionized water. The mixture consists of 4g of sodium dodecylbenzene, 16.52g of methyl methacrylate, and 0.18g of divinylbenzene; Pre-emulsion C is added to the third raw material tank, which consists of 0.048g of sodium dodecylbenzenesulfonate, 0.024g of secondary alcohol polyoxyethylene ether, 8.4g of deionized water, and 0.76g of butyl acrylate; Pre-emulsion D is added to the fourth raw material tank, which consists of 0.072g of sodium dodecylbenzenesulfonate, 0.036g of secondary alcohol polyoxyethylene ether, 16.8g of deionized water, 6.8g of isobornyl methacrylate, 11.2g of tert-butyl acrylate, and 0.18g of divinylbenzene;

[0073] Connect the second raw material tank to the first raw material tank; connect the third raw material tank to the second raw material tank; connect the fourth raw material tank to the reaction apparatus. Dissolve 0.108g of AIBN in 8.4g of deionized water, and dissolve 0.144g of AIBN in 8.4g of deionized water. After complete dissolution, connect them to the reaction apparatus respectively.

[0074] Add 10wt% of preemulsion A to the reaction apparatus. After the temperature rises to the polymerization temperature of 76℃, dissolve 0.036g of AIBN in 8.4g of deionized water and add it to the reaction apparatus to carry out seed emulsion polymerization.

[0075] Once the temperature reaches 80℃, pre-emulsion A is added dropwise over 1.5 hours. Pre-emulsion B from the second raw material tank is then added dropwise to the first raw material tank, with the addition completed over 0.3 hours. Pre-emulsion C from the third raw material tank is then added dropwise to the second raw material tank, with the addition completed over 0.06 hours. Simultaneously, 0.108 g of AIBN dissolved in 8.4 g of deionized water is added dropwise over 1.5 hours. After the polymerization reaction, the core-layer polymer is obtained.

[0076] Preparation of core-shell polymer emulsions:

[0077] The pre-emulsion D from the fourth raw material tank was introduced into the reaction apparatus and added dropwise over 2 hours. At the same time, 0.144 g of AIBN dissolved in 8.4 g of deionized water was added dropwise. After the polymerization reaction, the mixture was kept at 90 °C for 1 hour, and the pH was adjusted to 7-8 with ammonia water to obtain a polyacrylate core-shell emulsion.

[0078] A polyacrylate core-shell emulsion was coated onto a glass substrate using a four-sided coating tool to form a wet film with a thickness of 90 micrometers, which was then dried in an oven at 72.5°C.

[0079] The obtained polyacrylate core-shell emulsion was subjected to DSC testing, and the Tg of the core polymer was 95℃, the Tg of the shell polymer was 60℃, and the glass transition temperature difference between the core and shell was 35℃. The average Tg of the core and shell was 77.5℃. In the examples, the film-forming temperature range was 72.5~82.5℃, and the film-forming temperature of 72.5℃ was selected in this example.

[0080] Example 3: Within the glass transition temperature design range of the present invention, the core Tg = 45℃, the shell Tg = 10℃, and the core-shell glass transition temperature difference is 35℃; the surfactant is 1%, and the oven is dried at 30℃.

[0081] Preparation of core polymer emulsion:

[0082] Add 0.036g of SR-10 surfactant, 25.2g of deionized water, and 0.036g of sodium bicarbonate pH buffer to the reaction apparatus. After stirring and dispersing at 220rpm for 10min, add 0.36g of acrylamide. Add pre-emulsion A to the first raw material tank. Pre-emulsion A consists of 0.072g of SR-10 surfactant, 8.4g of deionized water, and 0.36g of methacrylic acid. Add pre-emulsion B to the second raw material tank. Pre-emulsion B consists of 0.024g and 0.048g of secondary alcohol polyoxyethylene ether surfactant, 8.4g of deionized water, 12.52g of methyl methacrylate, and 0.18g of diacetone acrylamide-adipic hydrazide. Add pre-emulsion C to the third raw material tank. Pre-emulsion C consists of 0.024g and 0.048g of secondary alcohol polyoxyethylene ether surfactant, 0.072g and 0.048g of SR-10 surfactant, 0.048g and 0.048g of sodium bicarbonate pH buffer. The mixture consists of SR-10, 8.4g of deionized water, and 4.76g of butyl acrylate; pre-emulsion D is added to the fourth raw material tank. Pre-emulsion D consists of 0.036g of surfactant secondary alcohol polyoxyethylene ether, 0.072g of SR-10, 16.8g of deionized water, 3.56g of lauryl methacrylate, 14.44g of tert-butyl acrylate, and 0.18g of diacetone acrylamide-adipamide hydrazide.

[0083] Connect the second raw material tank to the first raw material tank; connect the third raw material tank to the second raw material tank; connect the fourth raw material tank to the reaction apparatus. Dissolve 0.108g of TBHP-ascorbic acid in 8.4g of deionized water, and dissolve 0.144g of TBHP-ascorbic acid in 8.4g of deionized water. After thorough dissolution, connect them to the reaction apparatus respectively.

[0084] Add 10 wt% of pre-emulsion A to the reaction apparatus, and wait for the temperature to rise to the polymerization temperature of 76°C before adding...

[0085] 0.036g TBHP-ascorbic acid was dissolved in 8.4g deionized water and added to the reaction apparatus to carry out seed emulsion polymerization;

[0086] When the temperature rises to 80℃, pre-emulsion A is added dropwise over 1.5 hours. Pre-emulsion B from the second raw material tank is added dropwise to the first raw material tank, and the addition is completed over 0.3 hours. Pre-emulsion C from the third raw material tank is added dropwise to the second raw material tank, and the addition is completed over 0.06 hours. At the same time, 0.108 g of TBHP-ascorbic acid dissolved in 8.4 g of deionized water is added dropwise over 1.5 hours. After the polymerization reaction, the core polymer is obtained.

[0087] Preparation of core-shell polymer emulsions:

[0088] The pre-emulsion D from the fourth raw material tank was introduced into the reaction apparatus and added dropwise over 2 hours. At the same time, 0.144 g of TBHP-ascorbic acid dissolved in 8.4 g of deionized water was added dropwise. After the polymerization reaction, the mixture was kept at 90 °C for 1 hour and the pH was adjusted to 7-8 with ammonia water to obtain a polyacrylate core-shell emulsion.

[0089] A polyacrylate core-shell emulsion was coated onto a glass substrate using a four-sided coating tool to form a wet film with a thickness of 90 micrometers, which was then dried in an oven at 30°C.

[0090] The obtained polyacrylate core-shell emulsion was subjected to DSC testing, and the Tg of the core polymer was 45℃, the Tg of the shell polymer was 10℃, and the glass transition temperature difference between the core and shell was 35℃; the average Tg of the core and shell was 27.5℃. In this embodiment, the film-forming temperature range is 22.5~32.5℃, and a film-forming temperature of 30℃ is selected in this embodiment.

[0091] Comparative Example 1

[0092] Preparation of core polymer emulsion:

[0093] Add 0.036 g of sodium dodecyl sulfate (SLS) surfactant, 25.2 g of deionized water, and 0.036 g of sodium bicarbonate pH buffer to the reaction apparatus. After stirring and dispersing at 220 rpm for 10 min, add 0.36 g of acrylamide. Add pre-emulsion A to the first raw material tank. Pre-emulsion A consists of 0.072 g of sodium dodecyl sulfate surfactant, 8.4 g of deionized water, and 0.36 g of methacrylic acid. Add pre-emulsion B to the second raw material tank. Pre-emulsion B consists of 0.048 g of sodium dodecyl sulfate surfactant, 0.024 g of secondary alcohol polyoxyethylene ether, and 8.4 g of deionized water. The mixture consists of 16.43g of methyl methacrylate and 0.18g of allyl methacrylate. Pre-emulsion C is added to the third raw material tank. Pre-emulsion C consists of 0.048g of sodium dodecyl sulfate surfactant, 0.024g of secondary alcohol polyoxyethylene ether, 8.4g of deionized water, and 0.85g of butyl acrylate. Pre-emulsion D is added to the fourth raw material tank. Pre-emulsion D consists of 0.072g of sodium dodecyl sulfate, 0.036g of secondary alcohol polyoxyethylene ether, 16.8g of deionized water, 6.8g of isobornyl methacrylate, 11.2g of tert-butyl acrylate, and 0.18g of allyl methacrylate.

[0094] Connect the second raw material tank to the first raw material tank; connect the third raw material tank to the second raw material tank; connect the fourth raw material tank to the reaction apparatus. Dissolve 0.108g of ammonium persulfate in 8.4g of deionized water, and dissolve 0.144g of ammonium persulfate in 8.4g of deionized water. After complete dissolution, connect them to the reaction apparatus respectively.

[0095] Add 10 wt% of pre-emulsion A to the reaction apparatus. After the temperature rises to the polymerization temperature of 76°C, dissolve 0.036 g of ammonium persulfate in 8.4 g of deionized water and add it to the reaction apparatus to carry out seed emulsion polymerization.

[0096] Once the temperature reaches 80℃, pre-emulsion A is added dropwise over 1.5 hours. Pre-emulsion B from the second raw material tank is then added dropwise to the first raw material tank, with the addition completed over 0.3 hours. Pre-emulsion C from the third raw material tank is then added dropwise to the second raw material tank, with the addition completed over 0.06 hours. Simultaneously, 0.108 g of ammonium persulfate dissolved in 8.4 g of deionized water is added dropwise over 1.5 hours. After the polymerization reaction, the core polymer is obtained.

[0097] Preparation of core-shell polymer emulsions:

[0098] The pre-emulsion D from the fourth raw material tank was introduced into the reaction apparatus and added dropwise over 2 hours. Simultaneously, 0.144 g of ammonium persulfate dissolved in 8.4 g of deionized water was added dropwise. The mixture was kept at 90 °C for 1 hour, and the pH was adjusted to 7-8 with ammonia water to obtain a polyacrylate core-shell emulsion.

[0099] A polyacrylate core-shell emulsion was coated onto a glass substrate using a four-sided coating tool to form a wet film with a thickness of 90 micrometers, which was then dried in an oven at 72°C.

[0100] The obtained polyacrylate core-shell emulsion was subjected to DSC testing, and the Tg of the core polymer was 94℃, the Tg of the shell polymer was 60℃, and the glass transition temperature difference between the core and shell was 34℃. The average Tg of the core and shell was 77℃. In this invention, the film-forming temperature range is 72~82℃, and this comparative example selects a film-forming temperature of 72℃.

[0101] This comparative example exceeds the glass transition temperature design range defined by the technical measures of this invention. The core-shell glass transition temperature difference is less than 35°C, the core Tg = 94°C, and the shell Tg = 60°C. The surfactant content is 1%, and it is dried in an oven at 72°C. The protrusions are not obvious, the contact angle is low, and the matte finish is insufficient.

[0102] Comparative Example 2: The core-shell glass transition temperature difference exceeded 60℃, with a core Tg of 95℃ and a shell Tg of 34℃; the surfactant concentration was 1%, and the film was dried in an oven at 60℃. The excessively large core-shell glass transition temperature difference caused cracking during film formation.

[0103] Preparation of core polymer emulsion:

[0104] In the reaction apparatus, 0.036 g of sodium dodecyl sulfate surfactant, 25.2 g of deionized water, and 0.036 g of sodium bicarbonate pH buffer were added. After stirring and dispersing at 220 rpm for 10 min, 0.36 g of acrylamide was added. Pre-emulsion A, composed of 0.072 g of sodium dodecyl sulfate surfactant, 8.4 g of deionized water, and 0.36 g of methacrylic acid, was added to the first raw material tank. Pre-emulsion B, composed of 0.048 g of sodium dodecyl sulfate surfactant, 0.024 g of secondary alcohol polyoxyethylene ether, and 8.4 g of deionized water, was added to the second raw material tank. The mixture consists of 16.52 g of methyl methacrylate and 0.18 g of allyl methacrylate. Pre-emulsion C, composed of 0.048 g of sodium dodecyl sulfate, 0.024 g of secondary alcohol polyoxyethylene ether, 8.4 g of deionized water, and 0.76 g of butyl acrylate, is added to the third raw material tank. Pre-emulsion D, composed of 0.072 g of sodium dodecyl sulfate, 0.036 g of secondary alcohol polyoxyethylene ether, 16.8 g of deionized water, 0.1 g of lauryl methacrylate, 17.9 g of tert-butyl acrylate, and 0.18 g of allyl methacrylate, is added to the fourth raw material tank. Other examples and comparative examples are described with slight modifications.

[0105] Connect the second raw material tank to the first raw material tank; connect the third raw material tank to the second raw material tank; connect the fourth raw material tank to the reaction apparatus. Dissolve 0.108g of ammonium persulfate in 8.4g of deionized water, and dissolve 0.144g of ammonium persulfate in 8.4g of deionized water. After complete dissolution, connect them to the reaction apparatus respectively.

[0106] Add 10 wt% of pre-emulsion A to the reaction apparatus. After the temperature rises to the polymerization temperature of 76°C, dissolve 0.036 g of ammonium persulfate in 8.4 g of deionized water and add it to the reaction apparatus to carry out seed emulsion polymerization.

[0107] Once the temperature reaches 80℃, pre-emulsion A is added dropwise over 1.5 hours. Pre-emulsion B from the second raw material tank is then added dropwise to the first raw material tank, with the addition completed over 0.3 hours. Pre-emulsion C from the third raw material tank is then added dropwise to the second raw material tank, with the addition completed over 0.06 hours. Simultaneously, 0.108 g of ammonium persulfate dissolved in 8.4 g of deionized water is added dropwise over 1.5 hours. After the polymerization reaction, the core polymer is obtained.

[0108] Preparation of core-shell polymer emulsions:

[0109] The pre-emulsion D from the fourth raw material tank was introduced into the reaction apparatus and added dropwise over 2 hours. Simultaneously, 0.144 g of ammonium persulfate dissolved in 8.4 g of deionized water was added dropwise. The mixture was kept at 90 °C for 1 hour, and the pH was adjusted to 7-8 with ammonia water to obtain a polyacrylate core-shell emulsion.

[0110] A polyacrylate core-shell emulsion was coated onto a glass substrate using a four-sided coating tool to form a 90-micron thick wet film, which was then dried in an oven at 60°C.

[0111] The obtained polyacrylate core-shell emulsion was subjected to DSC testing, and the Tg of the core polymer was 95℃, the Tg of the shell polymer was 34℃, and the glass transition temperature difference between the core and shell was 61℃; the average Tg of the core and shell was 64.5℃. In this invention, the film-forming temperature range is 59.5~69.5℃, and this comparative example selects a film-forming temperature of 60℃.

[0112] Comparative Example 3: Core Tg = 96℃, shell Tg = 61℃, core-shell glass transition temperature difference = 35℃, dried in an oven at 75℃; surfactant content: 1%.

[0113] Preparation of core polymer emulsion:

[0114] Add 0.036 g of sodium dodecyl sulfate surfactant, 25.2 g of deionized water, and 0.036 g of sodium bicarbonate pH buffer to the reaction apparatus. After stirring and dispersing at 220 rpm for 10 min, add 0.36 g of acrylamide. Add pre-emulsion A to the first raw material tank. Pre-emulsion A consists of 0.072 g of sodium dodecyl sulfate surfactant, 8.4 g of deionized water, and 0.36 g of methacrylic acid. Add pre-emulsion B to the second raw material tank. Pre-emulsion B consists of 0.048 g of sodium dodecyl sulfate surfactant, 0.024 g of secondary alcohol polyoxyethylene ether, 8.4 g of deionized water, and 0.36 g of acrylamide. The mixture consists of 16.59g of methyl acrylate and 0.18g of allyl methacrylate. Pre-emulsion C is added to the third raw material tank. Pre-emulsion C consists of 0.048g of sodium dodecyl sulfate surfactant, 0.024g of secondary alcohol polyoxyethylene ether, 8.4g of deionized water, and 0.69g of butyl acrylate. Pre-emulsion D is added to the fourth raw material tank. Pre-emulsion D consists of 0.072g of sodium dodecyl sulfate, 0.036g of secondary alcohol polyoxyethylene ether, 16.8g of deionized water, 7.16g of isobornyl methacrylate, 10.84g of tert-butyl acrylate, and 0.18g of allyl methacrylate.

[0115] Connect the second raw material tank to the first raw material tank; connect the third raw material tank to the second raw material tank; connect the fourth raw material tank to the reaction apparatus. Dissolve 0.108g of ammonium persulfate in 8.4g of deionized water, and dissolve 0.144g of ammonium persulfate in 8.4g of deionized water. After complete dissolution, connect them to the reaction apparatus respectively.

[0116] Add 10 wt% of pre-emulsion A to the reaction apparatus. After the temperature rises to the polymerization temperature of 76°C, dissolve 0.036 g of ammonium persulfate in 8.4 g of deionized water and add it to the reaction apparatus to carry out seed emulsion polymerization.

[0117] Once the temperature reaches 80℃, pre-emulsion A is added dropwise over 1.5 hours. Pre-emulsion B from the second raw material tank is then added dropwise to the first raw material tank, with the addition completed over 0.3 hours. Pre-emulsion C from the third raw material tank is then added dropwise to the second raw material tank, with the addition completed over 0.06 hours. Simultaneously, 0.108 g of ammonium persulfate dissolved in 8.4 g of deionized water is added dropwise over 1.5 hours. After the polymerization reaction, the core polymer is obtained.

[0118] Preparation of core-shell polymer emulsions:

[0119] The pre-emulsion D from the fourth raw material tank was introduced into the reaction apparatus and added dropwise over 2 hours. Simultaneously, 0.144 g of ammonium persulfate dissolved in 8.4 g of deionized water was added dropwise. The mixture was kept at 90 °C for 1 hour, and the pH was adjusted to 7-8 with ammonia water to obtain a polyacrylate core-shell emulsion.

[0120] A polyacrylate core-shell emulsion was coated onto a glass substrate using a four-sided coating tool to form a wet film with a thickness of 90 micrometers, which was then dried in an oven at 75°C.

[0121] The obtained polyacrylate core-shell emulsion was subjected to DSC testing, and the Tg of the core polymer was 96℃, the Tg of the shell polymer was 61℃, and the glass transition temperature difference between the core and shell was 35℃. The average Tg of the core and shell was 78.5℃. In this comparative example, a film-forming temperature of 75℃ was selected. In this invention, the film-forming temperature range is 73.5~83.5℃.

[0122] Comparative Example 4: Core Tg = 95℃, Shell Tg = 35℃, core-shell glass transition temperature difference = 60℃; surfactant content 1%, dried in an oven at 75℃.

[0123] Preparation of core polymer emulsion:

[0124] Add 0.036 g of sodium dodecyl sulfate surfactant, 25.2 g of deionized water, and 0.036 g of sodium bicarbonate pH buffer to the reaction apparatus. After stirring and dispersing at 220 rpm for 10 min, add 0.36 g of acrylamide. Add pre-emulsion A to the first raw material tank. Pre-emulsion A consists of 0.072 g of sodium dodecyl sulfate surfactant, 8.4 g of deionized water, and 0.36 g of methacrylic acid. Add pre-emulsion B to the second raw material tank. Pre-emulsion B consists of 0.048 g of sodium dodecyl sulfate surfactant, 0.024 g of secondary alcohol polyoxyethylene ether, and... The mixture consists of 8.4g of deionized water, 16.52g of methyl methacrylate, and 0.18g of allyl methacrylate. Pre-emulsion C is added to the third raw material tank. Pre-emulsion C consists of 0.048g of sodium dodecyl sulfate surfactant, 0.024g of secondary alcohol polyoxyethylene ether, 8.4g of deionized water, and 0.76g of butyl acrylate. Pre-emulsion D is added to the fourth raw material tank. Pre-emulsion D consists of 0.072g of sodium dodecyl sulfate, 0.036g of secondary alcohol polyoxyethylene ether, 16.8g of deionized water, 18g of tert-butyl acrylate, and 0.18g of allyl methacrylate.

[0125] Connect the second raw material tank to the first raw material tank; connect the third raw material tank to the second raw material tank; connect the fourth raw material tank to the reaction apparatus. Dissolve 0.108g of ammonium persulfate in 8.4g of deionized water, and dissolve 0.144g of ammonium persulfate in 8.4g of deionized water. After complete dissolution, connect them to the reaction apparatus respectively.

[0126] Add 10 wt% of pre-emulsion A to the reaction apparatus. After the temperature rises to the polymerization temperature of 76°C, dissolve 0.036 g of ammonium persulfate in 8.4 g of deionized water and add it to the reaction apparatus to carry out seed emulsion polymerization.

[0127] Once the temperature reaches 80℃, pre-emulsion A is added dropwise over 1.5 hours. Pre-emulsion B from the second raw material tank is then added dropwise to the first raw material tank, with the addition completed over 0.3 hours. Pre-emulsion C from the third raw material tank is then added dropwise to the second raw material tank, with the addition completed over 0.06 hours. Simultaneously, 0.108 g of ammonium persulfate dissolved in 8.4 g of deionized water is added dropwise over 1.5 hours. After the polymerization reaction, the core polymer is obtained.

[0128] Preparation of core-shell polymer emulsions:

[0129] The pre-emulsion D from the fourth raw material tank was introduced into the reaction apparatus and added dropwise over 2 hours. Simultaneously, 0.144 g of ammonium persulfate dissolved in 8.4 g of deionized water was added dropwise. The mixture was kept at 90 °C for 1 hour, and the pH was adjusted to 7-8 with ammonia water to obtain a polyacrylate core-shell emulsion.

[0130] A polyacrylate core-shell emulsion was coated onto a glass substrate using a four-sided coating tool to form a wet film with a thickness of 90 micrometers, which was then dried in an oven at 75°C.

[0131] The obtained polyacrylate core-shell emulsion was subjected to DSC testing, yielding a core polymer Tg of 95°C and a shell polymer Tg of 35°C, with a core-shell glass transition temperature difference of 60°C. The average Tg of the core and shell was 65°C. This comparative example selected a film-forming temperature of 75°C, which is outside the 60–70°C range defined by the technical measures of this invention. A 90-micron wet film was coated onto a glass substrate using a four-sided coating tool and dried in an oven at 75°C.

[0132] Comparative Example 5: Core Tg = 95℃, Shell Tg = 35℃, core-shell glass transition temperature difference = 60℃; surfactant content 1%, dried in an oven at 55℃.

[0133] Preparation of core polymer emulsion:

[0134] Add 0.036 g of sodium dodecyl sulfate surfactant, 25.2 g of deionized water, and 0.036 g of sodium bicarbonate pH buffer to the reaction apparatus. After stirring and dispersing at 220 rpm for 10 min, add 0.36 g of acrylamide. Add pre-emulsion A to the first raw material tank. Pre-emulsion A consists of 0.072 g of sodium dodecyl sulfate surfactant, 8.4 g of deionized water, and 0.36 g of methacrylic acid. Add pre-emulsion B to the second raw material tank. Pre-emulsion B consists of 0.048 g of sodium dodecyl sulfate surfactant, 0.024 g of secondary alcohol polyoxyethylene ether, and... The mixture consists of 8.4g of deionized water, 16.52g of methyl methacrylate, and 0.18g of allyl methacrylate. Pre-emulsion C is added to the third raw material tank. Pre-emulsion C consists of 0.048g of sodium dodecyl sulfate surfactant, 0.024g of secondary alcohol polyoxyethylene ether, 8.4g of deionized water, and 0.76g of butyl acrylate. Pre-emulsion D is added to the fourth raw material tank. Pre-emulsion D consists of 0.072g of sodium dodecyl sulfate, 0.036g of secondary alcohol polyoxyethylene ether, 16.8g of deionized water, 18g of tert-butyl acrylate, and 0.18g of allyl methacrylate.

[0135] Connect the second raw material tank to the first raw material tank; connect the third raw material tank to the second raw material tank; connect the fourth raw material tank to the reaction apparatus. Dissolve 0.108g of ammonium persulfate in 8.4g of deionized water, and dissolve 0.144g of ammonium persulfate in 8.4g of deionized water. After complete dissolution, connect them to the reaction apparatus respectively.

[0136] Add 10 wt% of pre-emulsion A to the reaction apparatus. After the temperature rises to the polymerization temperature of 76°C, dissolve 0.036 g of ammonium persulfate in 8.4 g of deionized water and add it to the reaction apparatus to carry out seed emulsion polymerization.

[0137] Once the temperature reaches 80℃, pre-emulsion A is added dropwise over 1.5 hours. Pre-emulsion B from the second raw material tank is then added dropwise to the first raw material tank, with the addition completed over 0.3 hours. Pre-emulsion C from the third raw material tank is then added dropwise to the second raw material tank, with the addition completed over 0.06 hours. Simultaneously, 0.108 g of ammonium persulfate dissolved in 8.4 g of deionized water is added dropwise over 1.5 hours. After the polymerization reaction, the core polymer is obtained.

[0138] Preparation of core-shell polymer emulsions:

[0139] The pre-emulsion D from the fourth raw material tank was introduced into the reaction apparatus and added dropwise over 2 hours. Simultaneously, 0.144 g of ammonium persulfate dissolved in 8.4 g of deionized water was added dropwise. The mixture was kept at 90 °C for 1 hour, and the pH was adjusted to 7-8 with ammonia water to obtain a polyacrylate core-shell emulsion.

[0140] A polyacrylate core-shell emulsion was coated onto a glass substrate using a four-sided coating tool to form a wet film with a thickness of 90 micrometers, which was then dried in an oven at 55°C.

[0141] The obtained polyacrylate core-shell emulsion was subjected to DSC testing, and the Tg of the core polymer was 95℃, the Tg of the shell polymer was 35℃, and the glass transition temperature difference between the core and shell was 60℃. The average Tg of the core and shell was 65℃. In this comparative example, a film-forming temperature of 55℃ was selected, which is within the film-forming temperature range of 60-70℃ defined by the technical measures of this invention.

[0142] Comparative Example 6: The core-shell glass transition temperature difference was less than 35℃, core Tg = 94℃, shell Tg = 60℃; surfactant content was 1%, and the product was dried in an oven at 90℃. Almost no protrusions were observed.

[0143] Preparation of core polymer emulsion:

[0144] Add 0.036 g of sodium dodecyl sulfate (SLS) surfactant, 25.2 g of deionized water, and 0.036 g of sodium bicarbonate pH buffer to the reaction apparatus. After stirring and dispersing at 220 rpm for 10 min, add 0.36 g of acrylamide. Add pre-emulsion A to the first raw material tank. Pre-emulsion A consists of 0.072 g of sodium dodecyl sulfate surfactant, 8.4 g of deionized water, and 0.36 g of methacrylic acid. Add pre-emulsion B to the second raw material tank. Pre-emulsion B consists of 0.048 g of sodium dodecyl sulfate surfactant, 0.024 g of secondary alcohol polyoxyethylene ether, and 8.4 g of deionized water. The mixture consists of 16.43g of methyl methacrylate and 0.18g of allyl methacrylate. Pre-emulsion C is added to the third raw material tank. Pre-emulsion C consists of 0.048g of sodium dodecyl sulfate surfactant, 0.024g of secondary alcohol polyoxyethylene ether, 8.4g of deionized water, and 0.85g of butyl acrylate. Pre-emulsion D is added to the fourth raw material tank. Pre-emulsion D consists of 0.072g of sodium dodecyl sulfate, 0.036g of secondary alcohol polyoxyethylene ether, 16.8g of deionized water, 6.8g of isobornyl methacrylate, 11.2g of tert-butyl acrylate, and 0.18g of allyl methacrylate.

[0145] Connect the second raw material tank to the first raw material tank; connect the third raw material tank to the second raw material tank; connect the fourth raw material tank to the reaction apparatus. Dissolve 0.108g of ammonium persulfate in 8.4g of deionized water, and dissolve 0.144g of ammonium persulfate in 8.4g of deionized water. After complete dissolution, connect them to the reaction apparatus respectively.

[0146] Add 10 wt% of pre-emulsion A to the reaction apparatus. After the temperature rises to the polymerization temperature of 76°C, dissolve 0.036 g of ammonium persulfate in 8.4 g of deionized water and add it to the reaction apparatus to carry out seed emulsion polymerization.

[0147] Once the temperature rises to 80℃, pre-emulsion A is added dropwise over 1.5 hours. Pre-emulsion B from the second raw material tank is then added dropwise to the first raw material tank, completing the addition within 0.3 hours. Pre-emulsion C from the third raw material tank is then added dropwise to the second raw material tank, completing the addition within 0.06 hours. Simultaneously, 0.108g of ammonium persulfate dissolved in 8.4g of deionized water is added dropwise over 1.5 hours to polymerize the core layer polymer after the polymerization reaction.

[0148] Preparation of core-shell polymer emulsions:

[0149] The pre-emulsion D from the fourth raw material tank was introduced into the reaction apparatus and added dropwise over 2 hours. Simultaneously, 0.144 g of ammonium persulfate dissolved in 8.4 g of deionized water was added dropwise. The mixture was kept at 90 °C for 1 hour, and the pH was adjusted to 7-8 with ammonia water to obtain a polyacrylate core-shell emulsion.

[0150] A polyacrylate core-shell emulsion was coated onto a glass substrate using a four-sided coating tool to form a 90-micron thick wet film, which was then dried in an oven at 90°C.

[0151] The obtained polyacrylate core-shell emulsion was subjected to DSC testing, and the Tg of the core polymer was 94℃, the Tg of the shell polymer was 60℃, and the difference in glass transition temperature between the core and the shell was 34℃. The average Tg of the core and the shell was 77℃. The film-forming temperature of 90℃ was selected in this comparison, which is not within the film-forming temperature selection range of 72 to 82℃ defined by the technical measures of this invention.

[0152] The above Examples 1-3 can be used to prepare hydrophobic coatings with excellent stain resistance and stable and long-lasting hydrophobic properties. The specific performance test results are shown in Table 1.

[0153] Table 1

[0154]

[0155] As can be seen from the comparison of the examples and comparative examples, the present invention introduces hydrophobic monomers into the shell layer of latex particles and adjusts the amount of soft and hard monomers added to the core and shell layers to ensure that the amount of hydrophobic monomers added to the shell layer accounts for 40% to 50% of the total monomer addition; the glass transition temperature of the shell layer is 45 to 95°C, the glass transition temperature of the core layer is 10 to 60°C, the difference in glass transition temperature between the core layer and the shell layer is controlled within 35°C to 60°C, and the glass transition temperature of the core layer is higher than that of the shell layer; most importantly, it is necessary to control the film-forming process of latex particles, control the film-forming temperature to be lower than the glass transition temperature of the core layer polymer and higher than the glass transition temperature of the shell layer polymer, and control the film-forming temperature to be 0 to 5°C higher or lower than the average glass transition temperature of the core layer and the shell layer, so that a uniform and consistent protrusion is formed on the coating surface to obtain a matte hydrophobic structure. Through the above control, during film formation, the latex particle shell layer reaches the minimum film-forming temperature at the microscopic level, resulting in fusion, while the core layer does not reach the minimum film-forming temperature and does not fuse. This leads to the formation of uniform and stable protrusions on the coating surface at the macroscopic level, increasing the coating roughness, increasing the contact angle, and improving stain resistance, while maintaining a matte finish. The matte, highly stain-resistant, hydrophobic polyacrylate emulsion coating of this invention can improve the storage stability and long-term performance of inkjet inks, exhibits excellent flowability without clogging problems, and enhances pencil hardness, adhesion, water resistance, and abrasion resistance, while expanding the ink contact angle range. The matte, highly stain-resistant, hydrophobic polyacrylate emulsion coating of this invention has a matte finish and a fine appearance, making it suitable for stain-resistant coatings in outdoor construction and equipment applications. It boasts excellent overall performance, adaptability to various outdoor environments, and long-term stable performance.

Claims

1. A matte, highly stain-resistant, hydrophobic polyacrylate emulsion coating, characterized in that, The film is obtained by coating a substrate surface with a polyacrylate core-shell emulsion and then heating it to form a film. The film-forming temperature is controlled to be lower than the glass transition temperature of the core polymer and higher than the glass transition temperature of the shell polymer, while the film-forming temperature is controlled to be 0~5°C higher or lower than the average of the glass transition temperatures of the core and shell polymers. The polyacrylate core-shell emulsion is obtained by adding a shell pre-emulsion and a first initiator dissolved in deionized water to the core polymer emulsion, polymerizing it at 80~82°C, coating the shell polymer on the core polymer, holding the reaction at 85~90°C for 1~1.5h, and then adjusting the pH. The glass transition temperature of the core polymer is 45~95°C, and the glass transition temperature of the shell polymer is 10~60°C. The difference between the glass transition temperatures of the core polymer and the shell polymer is controlled to be 35°C~60°C. Preparation of the core polymer emulsion: 5%~8% of the mass of preemulsion A is added to the seed monomer solution. The temperature is raised to the initiation temperature of 74~78℃, and then a second initiator dissolved in deionized water is added. The temperature is raised to 80~82℃, and simultaneously, preemulsion C is added to preemulsion B, preemulsion B is added to the remaining preemulsion A, and the remaining preemulsion A is added to the seed monomer solution. The rate at which preemulsion B is added to the remaining preemulsion A is 3-6 times that of the remaining preemulsion A added to the seed monomer solution, and the rate at which preemulsion C is added to preemulsion B is 3-6 times that of preemulsion B added to the remaining preemulsion A. Simultaneously, a third initiator is added to the seed monomer solution, and the reaction is carried out at 80~82℃ for 1~2 hours. The seed monomer solution is obtained by stirring and dispersing a first surfactant and a first deionized water, then adding a pH buffer and a first reactive monomer; the first reactive monomer is one or more of acrylamide, N-hydroxymethylacrylamide, and acrylic acid; The pre-emulsion A is composed of a second surfactant, a second deionized water, and a second reactive monomer, wherein the second reactive monomer is one or more of methacrylic acid, hydroxyethyl methacrylate, hydroxypropyl acrylate, and ethyl methacrylate. The pre-emulsion B is composed of a third surfactant, a third deionized water, and a third reactive monomer. The third reactive monomer is composed of a first hard monomer and a crosslinking monomer. The first hard monomer is one or more of methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobornyl methacrylate, tert-butyl methacrylate, and cyclohexyl methacrylate. The crosslinking monomer is one of allyl methacrylate, divinylbenzene, and diacetone acrylamide-adipamide. The pre-emulsion C is composed of a fourth surfactant, a fourth deionized water and a fourth reactive monomer. The fourth reactive monomer is a first soft monomer, which is one or more of butyl acrylate, lauryl methacrylate and isooctyl acrylate. The shell preemulsion is composed of a fifth surfactant, a fifth deionized water, and a fifth reactive monomer. The fifth reactive monomer comprises a second hard monomer and a crosslinking monomer. The second hard monomer is one or more of tert-butyl acrylate, methyl methacrylate, cyclohexyl methacrylate, and isobornyl methacrylate. The crosslinking monomer is one of allyl methacrylate, divinylbenzene, and diacetone acrylamide-adipic hydrazide. In the shell preemulsion, by mass percentage, the fifth surfactant accounts for 0.8% to 1.4%, the fifth deionized water accounts for 43.6% to 54.2%, and the fifth reactive monomer accounts for 45% to 55%.

2. The matte, highly stain-resistant, hydrophobic polyacrylate emulsion coating according to claim 1, characterized in that, The first surfactant and the second surfactant are one of reactive surfactants and anionic surfactants; the reactive surfactant is SR-10 surfactant; the anionic surfactant is one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, and sodium alkyl-acrylate-2-ethanesulfonate. The third, fourth, and fifth surfactants are one of reactive surfactants, anionic surfactants, and nonionic surfactants; the reactive surfactant is SR-10 surfactant; the anionic surfactant is one of sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, and sodium alkyl-acrylic acid-2-ethanesulfonate; the nonionic surfactant is a secondary alcohol polyoxyethylene ether nonionic surfactant. The fifth reactive monomer also includes a second soft monomer, which is one of butyl acrylate and lauryl methacrylate.

3. The matte, highly stain-resistant, hydrophobic polyacrylate emulsion coating according to claim 1, characterized in that, The first, second, and third initiators are one of redox initiators, persulfate initiators, or oil-soluble initiators; the pH buffer is sodium bicarbonate and / or sodium carbonate.

4. The matte, highly stain-resistant, hydrophobic polyacrylate emulsion coating according to claim 3, characterized in that, The redox initiator is one of the persulfate-thiol redox system and the TBHP-ascorbic acid redox system; the persulfate initiator is one of ammonium persulfate, potassium persulfate, and sodium persulfate; and the oil-soluble initiator is one of AIBA and AIBN.

5. The matte, highly stain-resistant, hydrophobic polyacrylate emulsion coating according to claim 1, characterized in that, The process of adding a shell pre-emulsion and a first initiator dissolved in deionized water to the core polymer emulsion comprises, by mass percentage, 45.9-47.45% core polymer emulsion, 45.9-47.45% shell pre-emulsion, 5%-8% deionized water, and 0.1%-0.2% first initiator; the pH adjustment is achieved by adding ammonia.

6. The matte, highly stain-resistant, hydrophobic polyacrylate emulsion coating according to claim 1, characterized in that, In the preparation of the core polymer emulsion, by mass percentage, the seed monomer solution accounts for 8-10%, preemulsion A accounts for 16-25%, preemulsion B accounts for 35%-60%, and preemulsion C accounts for 16%-30%; In the seed monomer solution, based on 8-10% by mass, the first surfactant accounts for 0.005%-0.02%, the first deionized water accounts for 5.99%-6.97%, the pH buffer accounts for 0.005%-0.01%, and the first reactive monomer accounts for 2-3%. In the pre-emulsion A, based on a mass percentage of 16-25%, the second surfactant accounts for 0.02%-0.04%, the second deionized water accounts for 10.98%-16.96%, and the second reactive monomer accounts for 5%-8%. In the pre-emulsion B, based on a mass percentage of 35% to 60%, the third surfactant comprises 0.06% to 0.08%, the third deionized water comprises 14.94% to 29.92%, and the third reactive monomer comprises 20% to 30%. In the pre-emulsion C, by mass percentage (16% to 30%), there are 0.02% to 0.03% of the fourth surfactant, 7.98% to 15.97% of the fourth deionized water, and 8% to 14% of the fourth reactive monomer.

7. A method for preparing a matte, highly stain-resistant, hydrophobic polyacrylate emulsion coating as described in claim 1, characterized in that... Includes the following steps: 1) Preparation of polyacrylate core-shell emulsion: Add shell pre-emulsion and first initiator dissolved in deionized water to the core polymer emulsion. After polymerization at 80~82℃, coat the shell polymer onto the core polymer and keep it at 85~90℃ for 1~1.5h. Control the glass transition temperature of the core polymer to 45~95℃, control the glass transition temperature of the shell polymer to 10~60℃, and control the glass transition temperatures of the core polymer and the shell polymer to 35℃~60℃. 2) Preparation of matte, highly stain-resistant, hydrophobic polyacrylate emulsion coating: The coating is obtained by coating a polyacrylate core-shell emulsion onto the surface of a substrate and then heating it to form a film. The film-forming temperature is controlled to be lower than the glass transition temperature of the core polymer and higher than the glass transition temperature of the shell polymer, and the film-forming temperature is controlled to be 0~5℃ higher or lower than the average of the glass transition temperatures of the core and shell polymers.

8. The application of the matte, highly stain-resistant, hydrophobic polyacrylate emulsion coating as described in claim 1 in the preparation of inkjet ink coatings, matte coatings, and stain-resistant coatings.

Images