High-hardness easy-to-form industrial paint emulsion and preparation method thereof

Abstract

The application discloses an emulsion for high-hardness easy-to-form industrial paint and a preparation method thereof, and belongs to the technical field of high polymer emulsion polymerization, and particularly relates to an acrylate emulsion for industrial protective paint and a preparation process thereof. The preparation method comprises preparing a pre-emulsion and a segmented polymerization reaction. Compared with common industrial protective paint, the application has good normal-temperature film-forming property, guarantees that a paint film is dense, smooth, crack-free and pinhole-free, has sufficient hardness and wear resistance, resists bumping and scratching, and prolongs the service life of the coating. In addition, the emulsion glass transition temperature can be accurately controlled, industrial paint formulas for different construction temperatures and different use scenarios are adapted, and the process controllability is extremely strong. The functional monomers are directed to the surface layer of the paint film for strengthening, monomer waste is reduced, raw material cost is reduced, and economic benefits are improved.

Description

Technical Field

[0001] This invention belongs to the field of polymer emulsion polymerization technology and is applicable to industrial paints, protective topcoats, and engineering machinery coatings that have high requirements for film hardness, film-forming properties, and utilization rate. Specifically, it relates to an emulsion for high-hardness, easy-to-form film industrial paint and its preparation method. Background Technology

[0002] Industrial paint emulsions are widely used for the protection and decoration of metal substrates, engineering machinery, and industrial components. They require stringent film performance, demanding good film-forming properties at room temperature to ensure a dense, smooth film free of cracks and pinholes, while also possessing sufficient hardness and abrasion resistance to withstand impacts and scratches, extending the coating's lifespan. Currently, most commercially available industrial paint emulsions employ a one-step polymerization process, where monomers are uniformly mixed before addition, and a single initiator is used. Conventional emulsion preparation processes have several technical shortcomings, making it difficult to simultaneously achieve both film-forming properties and film hardness.

[0003] Conventional processes mix hard monomers, soft monomers, and functional monomers and add them in one go or at a constant rate. The functional monomers are randomly distributed inside and on the surface of the latex particles and cannot concentrate their effect on the surface of the paint film. To improve the hardness of the paint film, the amount of functional monomers needs to be greatly increased, which not only increases the cost but also damages the film-forming properties of the emulsion, leading to brittle paint film and reduced adhesion.

[0004] On the other hand, a single initiator system cannot achieve molecular weight gradient control. If thermal initiation is used throughout the process, the polymer molecular weight is relatively small, resulting in excellent film-forming properties, but insufficient hardness and poor wear resistance of the paint film. If low-temperature initiation is used throughout the process, the molecular weight is relatively large, and the hardness of the paint film meets the standard, but the emulsion film-forming temperature is high, making film formation difficult at room temperature, and the paint film is prone to problems such as pinholes and peeling.

[0005] Due to the above-mentioned process defects, traditional processes cannot accurately control the glass transition temperature (Tg) of the emulsion. If the Tg is too high, film formation will be difficult, and if the Tg is too low, the paint film will be soft and not scratch-resistant, making it difficult to adapt to the diverse construction and application scenarios of industrial paints.

[0006] In summary, existing industrial paint emulsions cannot simultaneously meet the requirements of excellent film-forming properties, high film hardness, and high monomer utilization, which restricts the performance upgrade of industrial protective coatings. A new preparation process is urgently needed to solve the above-mentioned pain points. Summary of the Invention

[0007] To address the problems existing in the prior art, this invention provides a high-hardness, easily film-forming industrial paint emulsion and its preparation method. By precisely controlling the temperature and adding monomers dropwise and using dual initiators for stepwise initiation, the latex particle structure can be optimized and the molecular weight gradient can be controlled. Under the premise of ensuring that the emulsion can easily form a film at room temperature, the hardness of the paint film can be greatly improved, while improving the monomer utilization rate and reducing the production cost.

[0008] The specific technical solution adopted in this invention is as follows:

[0009] A high-hardness, easily film-forming industrial paint emulsion includes a first monomer pre-emulsion and a second monomer pre-emulsion, as well as polymerization raw materials and post-treatment agents.

[0010] The first monomer pre-emulsion comprises 175-185 parts of deionized water, 20-30 parts of n-butyl acrylate, 75-85 parts of 2-ethylhexyl acrylate, 0.8-1.2 parts of methacrylic acid, 30-40 parts of methyl methacrylate, 230-240 parts of styrene, 5-7 parts of hydroxypropyl methacrylate, and 2.8-5.2 parts of a first compound emulsifier.

[0011] The second monomer pre-emulsion comprises 40-50 parts deionized water, 10-14 parts ethyl acrylate, 45-55 parts methyl methacrylate, 3-7 parts 2-ethylhexyl acrylate, 6-10 parts methacrylic acid, 0.8-1.2 parts silane coupling agent, 5-7 parts hydroxyethyl acrylate, and 1.4-2.2 parts second compound emulsifier.

[0012] The polymerization raw materials are 215-225 parts of base deionized water, 0.8-1.2 parts of monomer emulsifier, initial low-temperature redox initiator, dropwise addition of low-temperature redox initiator, and 8-12 parts of thermal initiator.

[0013] The post-treatment agent includes 0.4-0.6 parts of defoamer and 2-4 parts of bactericide.

[0014] A method for synthesizing a high-hardness, easily film-forming industrial paint emulsion includes the following steps:

[0015] (1) Pre-emulsification: Prepare a first monomer pre-emulsion and a second monomer pre-emulsion, respectively, wherein:

[0016] In a pre-emulsification tank, the first compound emulsifier is completely dissolved in the deionized water required for the preparation of the first monomer pre-emulsification. The stirring speed is adjusted to 300-500 r / min. Other raw materials required for the preparation of the first monomer pre-emulsification are added and stirred for 30-40 min to obtain the first monomer pre-emulsification for later use. The second monomer pre-emulsification is prepared in the same way for later use.

[0017] (2) First stage polymerization: Add base deionized water, monomer emulsifier and 10% of the first monomer pre-emulsion to the polymerization reactor, stir and heat to 65-67℃, add the initial low temperature redox initiator, and keep the reaction at the temperature for 10-15 min; then add the remaining 90% of the first monomer pre-emulsion and the low temperature redox initiator at a uniform rate, and control the addition time to 2.5-3.5 h; after the addition is completed, keep the reaction at the temperature for 20-30 min, and detect the monomer conversion rate ≥98%, forming a high molecular weight latex particle core;

[0018] (3) Second stage polymerization: Heat the reaction system to 82-85℃, and after constant temperature, add the second monomer pre-emulsion dropwise at a variable rate. The variable rate dropwise is to first add at 1.32 parts / min for 25-35 min, then at 1.08 parts / min for 45-55 min, and then at 0.88 parts / min until the addition is completed. Simultaneously add the heating initiator at a rate of 0.0875 parts / min. After the addition is completed, keep warm and stir for 1-2 h.

[0019] (4) Post-treatment: Cool the system to below 40℃, adjust the pH of the emulsion to 7.0-8.0, stir evenly, add defoamer and bactericide, filter the material with a 200-300 mesh filter to obtain a high-hardness, easy-film-forming industrial paint emulsion.

[0020] The beneficial effects of this invention are:

[0021] This invention achieves latex particle structure optimization and molecular weight gradient regulation by precisely controlling the temperature of monomer dropwise addition and using dual initiators for stepwise initiation. While ensuring that the emulsion can easily form a film at room temperature, it significantly improves the hardness of the paint film, while increasing monomer utilization and reducing production costs.

[0022] This invention employs a step-by-step, rate-controlled dripping process for the first monomer pre-emulsion and the second monomer pre-emulsion to achieve surface enrichment of functional monomers, precisely control the glass transition temperature of the emulsion, and adapt to industrial paint formulations with different application temperatures and usage scenarios, resulting in extremely high process controllability.

[0023] The present invention maintains a stable monomer utilization rate of over 98%, with functional monomers concentrated on the surface of latex particles, acting directionally to strengthen the paint film surface. This eliminates the need for excessive addition of functional monomers, reducing monomer waste, lowering raw material costs, and improving economic efficiency.

[0024] The emulsion of this invention has excellent overall performance. The large molecular chains formed during the low-temperature oxidation-reduction initiation stage improve the stability, adhesion and water resistance of the emulsion. The small molecule surface layer formed during the thermal initiation stage achieves the enrichment of functional monomers on the surface, improves film-forming properties, and can form a film quickly at room temperature. The resulting emulsion has good storage stability and is not prone to demulsification and separation. The paint film has strong adhesion, water resistance, weather resistance and impact resistance, meeting the stringent requirements of industrial paints. Attached Figure Description

[0025] Figure 1 This is a comparative schematic diagram of the film-forming properties of the present invention;

[0026] Figure 2 This is a schematic diagram showing the water resistance comparison of the present invention;

[0027] Figure 3 This is a comparative schematic diagram of the salt spray resistance of the present invention; Detailed Implementation

[0028] The present invention will be further described below with reference to specific embodiments:

[0029] Example 1

[0030] (1) Pre-emulsification: Prepare a first monomer pre-emulsion and a second monomer pre-emulsion, respectively, wherein:

[0031] First monomer pre-emulsion: Add 175 parts of deionized water, 0.8 parts of nonionic emulsifier 407 (Clariant), and 2 parts of emulsifier RS610A25 to the first pre-emulsion reactor. Start stirring and set the speed to 300-500 r / min. Add 20 parts of n-butyl acrylate, 75 parts of 2-ethylhexyl acrylate, 0.8 parts of methacrylic acid, 30 parts of methyl methacrylate, 230 parts of styrene, and 5 parts of hydroxypropyl methacrylate in batches. Stir and mix evenly to obtain the first monomer pre-emulsion for later use.

[0032] Second monomer pre-emulsion: Add 40 parts of deionized water, 0.8 parts of isomeric tridecyl alcohol polyoxyethylene ether E-1310, 0.4 parts of reactive sulfonate emulsifier DNS-86, and 0.2 parts of fatty alcohol polyoxyethylene ether ammonium sulfate (AESA 28%) to the second pre-emulsion reactor. Start stirring at a speed of 300-500 r / min. Add 10 parts of ethyl acrylate, 45 parts of methyl methacrylate, 3 parts of 2-ethylhexyl acrylate, 6 parts of methacrylic acid, 0.8 parts of silane coupling agent A-151, and 5 parts of hydroxyethyl acrylate in batches. Stir and mix evenly to obtain the second monomer pre-emulsion for later use.

[0033] (2) First stage polymerization: Add 188.25 parts of base deionized water, 0.8 parts of reactive sulfonate emulsifier DNS-86 and 10% of the first monomer pre-emulsion to the reactor, start stirring, heat to 65-67℃, add the initial low temperature redox initiator aqueous solution, of which ammonium persulfate-sodium bisulfite 0.17 parts: 0.08 parts, deionized water 1.25 parts, keep the reaction at the temperature for 10-15 min; then add the remaining 90% of the first monomer pre-emulsion and the low temperature redox initiator aqueous solution at a uniform rate, of which ammonium persulfate-sodium bisulfite 0.44 parts: 0.26 parts, deionized water 17.5 parts, control the addition time to 2.5-3.5 h; after the addition is completed, keep the reaction at the temperature for 20-30 min to form high molecular weight latex particle core.

[0034] (3) Second stage polymerization: Heat the reaction system to 82-85℃, and after constant temperature, add the second monomer pre-emulsion dropwise at a variable speed. First, add at 1.32 parts / min for 30 min, then at 1.08 parts / min for 50 min, and then at 0.88 parts / min until the addition is complete. Simultaneously add 8 parts of 5% sodium persulfate aqueous solution at a dropping rate of 0.0875 parts / min. After the addition is complete, keep warm and stir for 1-2 h.

[0035] (4) Post-treatment: Cool the system to below 40℃, adjust the pH of the emulsion to 7.0-8.0, stir evenly, add 0.5 parts of defoamer NXZ (Shengnuopco) and 3 parts of bactericide BIT20 (Clariant), filter the material with a 200-300 mesh filter to obtain a high-hardness, easy-film-forming industrial paint emulsion.

[0036] Example 2

[0037] (1) Pre-emulsification: Prepare a first monomer pre-emulsion and a second monomer pre-emulsion, respectively, wherein:

[0038] First monomer pre-emulsion: Add 177 parts of deionized water, 0.9 parts of nonionic emulsifier 407 (Clariant), and 2.5 parts of emulsifier RS610A25 to the first pre-emulsion reactor. Start stirring and set the speed to 300-500 r / min. Add 23 parts of n-butyl acrylate, 78 parts of 2-ethylhexyl acrylate, 0.9 parts of methacrylic acid, 33 parts of methyl methacrylate, 233 parts of styrene, and 5.5 parts of hydroxypropyl methacrylate in batches. Stir and mix evenly to obtain the first monomer pre-emulsion.

[0039] Second monomer pre-emulsion: Add 42 parts of deionized water, 0.9 parts of isotridecyl alcohol polyoxyethylene ether E-1308, 0.45 parts of COPS-1, and 0.25 parts of fatty alcohol polyoxyethylene ether ammonium sulfate (AESA 28%) to the second pre-emulsion reactor. Start stirring and set the speed to 300-500 r / min. Add 11 parts of ethyl acrylate, 48 parts of methyl methacrylate, 4 parts of 2-ethylhexyl acrylate, 7 parts of methacrylic acid, 0.9 parts of silane coupling agent A-151, and 5.5 parts of hydroxyethyl acrylate in batches. Stir and mix evenly to obtain the second monomer pre-emulsion.

[0040] (2) First stage polymerization: Add 187.9 parts of base deionized water, 0.9 parts of reactive sulfonate emulsifier DNS-86 and 10% of the first monomer pre-emulsion to the reactor, start stirring, heat to 65-67℃, add the initial low temperature redox initiator aqueous solution, of which ammonium persulfate-sodium bisulfite 0.18 parts: 0.09 parts, deionized water 1.35 parts, keep the reaction at the temperature for 10-15 min; then add the remaining 90% of the first monomer pre-emulsion and the low temperature redox initiator aqueous solution at a uniform rate, of which ammonium persulfate-sodium bisulfite 0.47 parts: 0.28 parts, deionized water 18.75 parts, control the addition time to 2.5-3.5 h; after the addition is completed, keep the reaction at the temperature for 20-30 min to form high molecular weight latex particle core.

[0041] Step (3) the second stage polymerization and (4) the post-treatment are the same as in Example 1, except that the 5% sodium persulfate aqueous solution is 9 parts.

[0042] Example 3

[0043] (1) Pre-emulsification: Prepare a first monomer pre-emulsion and a second monomer pre-emulsion, respectively, wherein:

[0044] First monomer pre-emulsion: Add 180 parts of deionized water, 1.0 part of nonionic emulsifier 407 (Clariant), and 3 parts of emulsifier RS610A25 to the first pre-emulsion reactor. Start stirring and set the speed to 300-500 r / min. Add 25 parts of n-butyl acrylate, 80 parts of 2-ethylhexyl acrylate, 1.0 part of methacrylic acid, 35 parts of methyl methacrylate, 235 parts of styrene, and 6 parts of hydroxypropyl methacrylate in batches. Stir and mix evenly to obtain the first monomer pre-emulsion.

[0045] Second monomer pre-emulsion: Add 45 parts of deionized water, 1.0 part of isomeric tridecyl alcohol polyoxyethylene ether E-1310, 0.5 parts of reactive sulfonate emulsifier DNS-86, and 0.3 parts of fatty alcohol polyoxyethylene ether ammonium sulfate (AESA 28%) to the second pre-emulsion reactor. Start stirring and set the speed to 300-500 r / min. Add 12 parts of ethyl acrylate, 50 parts of methyl methacrylate, 5 parts of 2-ethylhexyl acrylate, 8 parts of methacrylic acid, 1.0 part of silane coupling agent A-151, and 6 parts of hydroxyethyl acrylate in batches. Stir and mix evenly to obtain the second monomer pre-emulsion.

[0046] (2) First stage polymerization: Add 188.5 parts of base deionized water, 1.0 part of reactive sulfonate emulsifier DNS-86 and 10% of the first monomer pre-emulsion to the reactor, start stirring, heat to 65-67℃, add the initial low temperature redox initiator aqueous solution, of which ammonium persulfate-sodium bisulfite 0.2 parts: 0.1 parts, deionized water 1.5 parts, keep the reaction at the temperature for 10-15 min; then add the remaining 90% of the first monomer pre-emulsion and the low temperature redox initiator aqueous solution at a uniform rate, of which ammonium persulfate-sodium bisulfite 0.5 parts: 0.3 parts, deionized water 20 parts, control the addition time to 2.5-3.5 h; after the addition is completed, keep the reaction at the temperature for 20-30 min to form high molecular weight latex particle core.

[0047] Step (3) Second stage polymerization and (4) Post-treatment are the same as in Example 1, except that the 5% sodium persulfate aqueous solution is 10 parts.

[0048] Example 4

[0049] (1) Pre-emulsification: Prepare a first monomer pre-emulsion and a second monomer pre-emulsion, respectively, wherein:

[0050] First monomer preemulsion: Add 183 parts of deionized water, 1.1 parts of nonionic emulsifier 407 (Clariant), and 3.5 parts of emulsifier RS610A25 to the first preemulsion reactor. Start stirring and set the speed to 300-500 r / min. Add 28 parts of n-butyl acrylate, 82 parts of 2-ethylhexyl acrylate, 1.1 parts of methacrylic acid, 37 parts of methyl methacrylate, 237 parts of styrene, and 6.5 parts of hydroxypropyl methacrylate in batches. Stir and mix evenly to obtain the first monomer preemulsion.

[0051] Second monomer preemulsion: Add 47 parts of deionized water, 1.1 parts of isotridecyl alcohol polyoxyethylene ether E-1308, 0.55 parts of COPS-1, and 0.35 parts of fatty alcohol polyoxyethylene ether ammonium sulfate (AESA 28%) to the second preemulsion reactor. Start stirring and set the speed to 300-500 r / min. Add 13 parts of ethyl acrylate, 52 parts of methyl methacrylate, 6 parts of 2-ethylhexyl acrylate, 9 parts of methacrylic acid, 1.1 parts of silane coupling agent A-151, and 6.5 parts of hydroxyethyl acrylate in batches. Stir and mix evenly to obtain the second monomer preemulsion.

[0052] (2) First stage polymerization: Add 188.1 parts of base deionized water, 1.1 parts of reactive sulfonate emulsifier DNS-86 and 10% of the first monomer pre-emulsion to the reactor, start stirring, heat to 65-67℃, add the initial low temperature redox initiator aqueous solution, of which ammonium persulfate-sodium bisulfite 0.22 parts: 0.11 parts, deionized water 1.65 parts, keep the reaction at the temperature for 10-15 min; then add the remaining 90% of the first monomer pre-emulsion and the low temperature redox initiator aqueous solution at a uniform rate, of which ammonium persulfate-sodium bisulfite 0.53 parts: 0.32 parts, deionized water 21.25 parts, control the addition time to 2.5-3.5 h; after the addition is completed, keep the reaction at the temperature for 20-30 min to form high molecular weight latex particle core.

[0053] Step (3) Second stage polymerization and (4) Post-treatment are the same as in Example 1, except that the 5% sodium persulfate aqueous solution is 11 parts.

[0054] Example 5

[0055] (1) Pre-emulsification: Prepare a first monomer pre-emulsion and a second monomer pre-emulsion, respectively, wherein:

[0056] First monomer preemulsion: Add 185 parts of deionized water, 1.2 parts of nonionic emulsifier 407 (Clariant), and 4 parts of emulsifier RS610A25 to the first preemulsion reactor. Start stirring and set the speed to 300-500 r / min. Add 30 parts of n-butyl acrylate, 85 parts of 2-ethylhexyl acrylate, 1.2 parts of methacrylic acid, 40 parts of methyl methacrylate, 240 parts of styrene, and 7 parts of hydroxypropyl methacrylate in batches. Stir and mix evenly to obtain the first monomer preemulsion.

[0057] Second monomer pre-emulsion: Add 50 parts of deionized water, 1.2 parts of isotridecyl alcohol polyoxyethylene ether E-1310, 0.6 parts of allyl ether ammonium sulfate, and 0.4 parts of fatty alcohol polyoxyethylene ether ammonium sulfate (AESA 28%) to the second pre-emulsion reactor. Start stirring and set the speed to 300-500 r / min. Add 14 parts of ethyl acrylate, 55 parts of methyl methacrylate, 7 parts of 2-ethylhexyl acrylate, 10 parts of methacrylic acid, 1.2 parts of silane coupling agent A-151, and 7 parts of hydroxyethyl acrylate in batches. Stir and mix evenly to obtain the second monomer pre-emulsion.

[0058] (2) First stage polymerization: Add 188.75 parts of base deionized water, 1.2 parts of reactive sulfonate emulsifier DNS-86 and 10% of the first monomer pre-emulsion to the reactor, start stirring, heat to 65-67℃, add the initial low temperature redox initiator aqueous solution, of which ammonium persulfate-sodium bisulfite 0.23 parts: 0.12 parts, deionized water 1.75 parts, keep the reaction at the temperature for 10-15 min; then add the remaining 90% of the first monomer pre-emulsion and the low temperature redox initiator aqueous solution at a uniform rate, of which ammonium persulfate-sodium bisulfite 0.56 parts: 0.34 parts, deionized water 22.5 parts, control the addition time to 2.5-3.5 h; after the addition is completed, keep the reaction at the temperature for 20-30 min to form high molecular weight latex particle core.

[0059] Step (3) the second stage of polymerization and (4) the post-treatment are the same as in Example 1, except that the 5% sodium persulfate aqueous solution is 12 parts.

[0060] The high-hardness, easy-film-forming industrial paint emulsion prepared according to the above examples is formulated as shown in Table 1.

[0061] Table 1

[0062]

[0063] The high-hardness, easy-film-forming industrial paint emulsion prepared according to the process of this invention was compared with a comparative example in terms of application performance. The comparative example was a similar competing industrial paint emulsion on the market. The following comparison focuses on film-forming properties, water resistance, and salt spray resistance.

[0064] 1. Film-forming properties: The high-hardness, easy-to-form-film industrial paint emulsion prepared in Example 3 of this invention was sprayed onto a slab without any film-forming aids and allowed to air dry at room temperature. The changes in paint film formation were observed. See details below. Figure 1 The comparative molding results were poor, the paint film was not completely continuous, and there were obvious cracks in the paint film. In contrast, the emulsion prepared in this application forms a film rapidly, resulting in a dense, smooth film without cracks or pinholes, while also exhibiting high surface hardness and scratch resistance. Therefore, the high-hardness, easily film-forming industrial paint emulsion prepared using the process of this invention has excellent film-forming properties.

[0065] 2. Water Resistance: A spray plate prepared with the high-hardness, easy-to-form industrial paint emulsion as described in Example 3 of this invention was dried and then soaked in water for 24 hours. The changes in the water resistance of the paint film were observed. See details below. Figure 2 The comparative sample showed severe whitening in the water-soaked portion, while the emulsion prepared in this application did not exhibit any particularly noticeable change. This demonstrates that the high-hardness, easily film-forming industrial paint emulsion prepared using the process of this invention possesses excellent water resistance.

[0066] 3. Salt spray resistance: After drying, the high-hardness, easily film-forming industrial paint emulsion prepared in Example 3 of this invention was subjected to a salt spray scribing test to observe the salt spray resistance of the paint film. See details for further information. Figure 3 In contrast, the rust spread was severe at the scratches in the comparative example, while the rust spread at the scratches in the emulsion prepared in this application was extremely low, and the paint film in the non-scratched areas remained intact and undamaged. Therefore, the high-hardness, easily film-forming industrial paint emulsion prepared using the process of this invention is significantly superior to conventional emulsifier systems and is suitable for light-duty anti-corrosion industrial paints.

Claims

1. A high-hardness, easily film-forming industrial paint emulsion, characterized in that: It includes a first monomer preemulsion and a second monomer preemulsion, as well as polymerization raw materials and post-treatment agents; The first monomer preemulsion comprises 175-185 parts of deionized water, 20-30 parts of n-butyl acrylate, 75-85 parts of 2-ethylhexyl acrylate, 0.8-1.2 parts of methacrylic acid, 30-40 parts of methyl methacrylate, 230-240 parts of styrene, 5-7 parts of hydroxypropyl methacrylate, and 2.8-5.2 parts of a first compound emulsifier; The second monomer pre-emulsion comprises 40-50 parts deionized water, 10-14 parts ethyl acrylate, 45-55 parts methyl methacrylate, 3-7 parts 2-ethylhexyl acrylate, 6-10 parts methacrylic acid, 0.8-1.2 parts silane coupling agent, 5-7 parts hydroxyethyl acrylate, and 1.4-2.2 parts second compound emulsifier; The polymerization raw materials are 207-213 parts of base deionized water, 0.8-1.2 parts of monomer emulsifier, 0.25-0.35 parts of initial low-temperature redox initiator, 0.7-0.9 parts of dropwise low-temperature redox initiator, and 8-12 parts of thermal initiator; The post-treatment agent includes 0.4-0.6 parts of defoamer and 2-4 parts of bactericide.

2. The high-hardness, easily film-forming industrial paint emulsion according to claim 1, characterized in that: The first compound emulsifier comprises 0.8-1.2 parts of nonionic emulsifier 407 and 2-4 parts of emulsifier RS610A25; The second compound emulsifier includes 0.8-1.2 parts of film-forming additive, 0.4-0.6 parts of weather-resistant additive, and 0.2-0.4 parts of stabilizing additive. The film-forming additive includes any one or a mixture of two of isomeric tridecyl alcohol polyoxyethylene ether E-1310 and 1308. The weather-resistant additive includes any one or a mixture of one or more of reactive sulfonate emulsifiers DNS-86, COPS-1, and allyl ether ammonium sulfate. The stabilizing additive is fatty alcohol polyoxyethylene ether ammonium sulfate.

3. The high-hardness, easily film-forming industrial paint emulsion according to claim 1, characterized in that: The initial low-temperature redox initiator was a mixed aqueous solution of ammonium persulfate and sodium bisulfite, with a mass ratio of ammonium persulfate to sodium bisulfite of 2:1, and deionized water was 5 times the mass of the salt. The dropwise added low-temperature redox initiator was a mixed aqueous solution of ammonium persulfate and sodium bisulfite, with a mass ratio of ammonium persulfate to sodium bisulfite of 5:3, and deionized water was 25 times the mass of the salt.

4. The high-hardness, easily film-forming industrial paint emulsion according to claim 1, characterized in that: The silane coupling agent is A-151.

5. The high-hardness, easily film-forming industrial paint emulsion according to claim 1, characterized in that: The monomeric emulsifier is the reactive sulfonate emulsifier DNS-86.

6. The high-hardness, easily film-forming industrial paint emulsion according to claim 1, characterized in that: The thermal initiator is a 5% sodium persulfate aqueous solution.

7. A method for preparing a high-hardness, easily film-forming industrial paint emulsion, used to prepare the high-hardness, easily film-forming industrial paint emulsion as described in claim 1, characterized in that: Includes the following steps, (1) Pre-emulsification: Prepare a first monomer pre-emulsion and a second monomer pre-emulsion, respectively, wherein: In a pre-emulsification tank, the first compound emulsifier is completely dissolved in the deionized water required for the preparation of the first monomer pre-emulsification. The stirring speed is adjusted to 300-500 r / min. Other raw materials required for the preparation of the first monomer pre-emulsification are added and stirred for 30-40 min to obtain the first monomer pre-emulsification for later use. The second monomer pre-emulsification is prepared in the same way for later use. (2) First stage polymerization: Add base deionized water, monomer emulsifier and 10% of the first monomer pre-emulsion to the polymerization reactor, stir and heat to 65-67℃, add the initial low temperature oxidation and reduction initiator, and keep the reaction at the temperature for 10-15 min; then add the remaining 90% of the first monomer pre-emulsion and the low temperature oxidation and reduction initiator at a uniform rate, and control the addition time to 2.5-3.5 h; after the addition is completed, keep the reaction at the temperature for 20-30 min to form the core of high molecular weight latex particles; (3) Second stage polymerization: Heat the reaction system to 82-85℃, and after maintaining the temperature, add the second monomer pre-emulsion dropwise at a variable speed, while simultaneously adding the heating initiator; after the addition is complete, keep the temperature and stir for 1-2 hours. (4) Post-treatment: Cool the system to below 40°C, adjust the pH of the emulsion to 7.0-8.0, stir evenly, add defoamer and bactericide, filter the material with a 200-300 mesh filter to obtain a high-hardness, easy-film-forming industrial paint emulsion.

8. The high-hardness, easily film-forming industrial paint emulsion according to claim 7, characterized in that: In step (3), the variable-speed dripping is first dripped at 1.32 parts / min for 25-35 minutes, then at 1.08 parts / min for 45-55 minutes, and then at 0.88 parts / min until the dripping is completed.

9. The high-hardness, easily film-forming industrial paint emulsion according to claim 7, characterized in that: In step (3), the thermal initiator is added at a rate of 0.0875 parts / min.

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