Water-based acrylic acid metal pretreatment emulsion as well as preparation method and application thereof

Abstract

The invention discloses a water-based acrylic acid metal pretreatment emulsion as well as a preparation method and application thereof, belongs to the technical field of water-based acrylic acid emulsions, and overcomes the defects of high deoiling and degreasing cost, environmental pollution and incomplete removal in the prior art. The water-based acrylic acid metal pretreatment emulsion comprises the following raw materials in parts by mass: 100-140 parts of a hard monomer; 120-170 parts by mass of a soft monomer; 30-60 parts by mass of a functional monomer; 5-15 parts by mass of an emulsifier; 0.1-0.5 part by mass of a buffering agent; 1-8 parts by mass of an oxidant; 0.1-0.5 part by mass of a reducing agent; 10-30 parts by mass of an auxiliary agent is added later; 600 to 680 parts by mass of water; the functional monomer comprises acrylamide, and the mass of the acrylamide accounts for 1.5-26% of the sum of the mass of the hard monomer, the mass of the soft monomer and the mass of the functional monomer. A paint film prepared from the water-based acrylic acid metal pretreatment emulsion has excellent water solubility.

Description

Technical Field

[0001] This invention belongs to the field of waterborne acrylic emulsion technology, specifically relating to a waterborne acrylic metal pretreatment emulsion, its preparation method, and its application. Background Technology

[0002] Metal pretreatment emulsions are used for the pretreatment of metal substrates. They are formed by roller coating a resin surface layer with different mechanical, physical and chemical properties from the substrate. Then, oil or grease is applied to the resin surface layer to meet the special functional requirements of the metal substrate such as wear resistance, corrosion resistance and oxidation resistance before final processing and molding. They are widely used in home appliances, construction, shipbuilding and other fields.

[0003] Before further processing, metal substrates are degreased with degreasing agents to remove the oil and grease previously applied to the resin surface. Currently, degreasing agents mainly include alkaline degreasing agents, emulsifying degreasing agents, and displacement degreasing agents. However, these degreasing agents often have problems such as high cost and environmental pollution, and they are also prone to leaving grease residues, which greatly affects the processing of metal substrates, especially precision substrates, causing problems such as shrinkage cavities and peeling. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the defects of high cost, environmental pollution and incomplete removal of oil and fat in the prior art, thereby providing an aqueous acrylic metal pretreatment emulsion, its preparation method and its application.

[0005] To this end, the present invention provides the following technical solution.

[0006] In a first aspect, the present invention provides an aqueous acrylic metal pretreatment emulsion, wherein the raw materials, by weight, include:

[0007]

[0008] The functional monomer includes acrylamide, which accounts for 1.5% to 26% of the total mass of the hard monomer, soft monomer and functional monomer, preferably 8% to 12%.

[0009]

[0010] In one possible embodiment, the water comprises 620-680 parts by weight;

[0011] In one possible embodiment, the waterborne acrylic metal pretreatment emulsion has a solids content of 33wt%-35wt%.

[0012] In one possible embodiment, the latex particles in the aqueous acrylic metal pretreated emulsion have a particle size of 200-1500 nm, preferably 400-800 nm.

[0013] In one possible embodiment, the viscosity of the aqueous acrylic metal pretreatment emulsion is 3000-18000 cps, preferably 5000-10000 cps, and more preferably 5000-8000 cps.

[0014] In one possible embodiment, the hard monomer includes one or more of butyl methacrylate, methyl methacrylate, and styrene;

[0015] Preferably, the hard monomer is selected from a combination containing methyl methacrylate and / or butyl methacrylate monomers;

[0016] In one possible embodiment, the soft monomer includes one or more of isooctyl acrylate, butyl acrylate, and ethyl acrylate;

[0017] In one possible embodiment, the functional monomer further includes one or more of methyl diacetone acrylamide, hydroxyethyl acrylate, methacrylic acid, and acrylic acid.

[0018] In one possible embodiment, the emulsifier comprises one or more of the following: sodium allyl oxypropanesulfonate (COPS-1), sodium dodecyl diphenyl ether disulfonate, polyoxyethylene polystyrene phenolic ether (710), sodium tridecyl alcohol polyoxyethylene ether sulfate, ethoxylated C12-14 alcohol (AE-07), sodium salt of sulfonated diphenyl ether tetrapropylene derivative (2A1), sodium allyl ether hydroxypropyl sulfonate, sodium dodecyl sulfate, and isomeric tridecyl alcohol polyoxyethylene (3) ether.

[0019] Optionally, the ethoxylated alcohol is an ethoxylated C12-14 alcohol.

[0020] Preferably, the emulsifier includes one or more of isotridecyl alcohol polyoxyethylene (3) ether, ethoxylated C12-14 alcohol (AE-07), and polyoxyethylene polystyrene phenol ether.

[0021] When preparing emulsions through emulsion polymerization, most emulsifiers tend to form new micelles, which, after initiating the reaction, form new latex particles, inhibiting their growth and resulting in a wide particle size distribution. However, this product uses emulsifiers with cloud points lower than the reaction temperature, such as isotridecyl alcohol polyoxyethylene (3) ether, polyoxyethylene polystyrene phenol ether (710), and ethoxylated C12-14 alcohol (AE-07). Above the cloud point, these emulsifiers have weak self-micelle-forming ability, which can effectively inhibit the formation of new micelles, ensuring the continuous growth of latex particles and preparing emulsions with large size and narrow distribution. This results in a decrease in film density during actual use, making it easier for water to penetrate, thus providing a prerequisite for better water solubility of the product.

[0022] In one possible embodiment, the buffer includes one or more of sodium bicarbonate, sodium carbonate, and ammonium bicarbonate;

[0023] In one possible embodiment, the oxidant includes one or more of ammonium persulfate, sodium persulfate, tert-butyl hydrogen peroxide, and hydrogen peroxide.

[0024] In one possible embodiment, the reducing agent includes one or more of sodium metabisulfite, isoascorbic acid, sodium hydrosulfite, sodium formaldehyde sulfoxylate, and FF6;

[0025] In one possible embodiment, the added additive includes at least one of a neutralizer, a defoamer, and a preservative.

[0026] Secondly, the present invention provides a method for preparing an aqueous acrylic metal pretreated emulsion, comprising the following steps:

[0027] Step 1: Add deionized water to the reactor, heat to 80-95℃, and add the first emulsifier to the bottom of the reactor;

[0028] Step 2: At 80-95℃, add a portion of the pre-emulsion and the first oxidant to the reactor and react for 10-30 minutes to obtain the seed emulsion;

[0029] Step 3: Add the remaining pre-emulsion and the second oxidant to the seed emulsion dropwise over a total time of 120-300 min.

[0030] Step 4: After the addition is complete, keep the temperature at 80-95℃, then cool it down to 55-75℃. Add the third oxidizing agent and reducing agent at 55-75℃, and continue to cool down to below 50℃. Add the additives after adding the third oxidizing agent to obtain the water-based acrylic metal pretreated emulsion.

[0031] Optionally, an adjuvant can be added after the emulsion is added to adjust its pH to 3.0-6.5.

[0032] In one possible embodiment, in step 4, the temperature is maintained at 80-95°C for 1-8 hours; preferably, it is maintained for 3-5 hours.

[0033] In one possible embodiment, in step 4, while maintaining the temperature at 80-95°C, the viscosity and particle size of the emulsion are monitored. After the viscosity reaches 3000-18000 cps and the particle size reaches 200-1500 nm, the temperature is lowered. Preferably, the temperature is lowered after the viscosity reaches 5000-8000 cps and the particle size reaches 400-800 nm.

[0034] In one possible embodiment, the pre-emulsion comprises hard monomers, soft monomers, functional monomers, a second emulsifier, a buffer, and deionized water.

[0035] In one possible embodiment, the method for preparing the pre-emulsion includes the following steps: adding deionized water, emulsifier, hard monomer, functional monomer, soft monomer, and buffer to a pre-emulsion kettle, and stirring at high speed for 20-30 minutes.

[0036] In one possible embodiment, the first emulsifier and the second emulsifier are independently selected from any one or more of the following: sodium allyloxypropanesulfonate (COPS-1), sodium dodecyl diphenyl ether disulfonate, polyoxyethylene polystyrene phenolic ether (710), sodium tridecyl alcohol polyoxyethylene ether sulfate, ethoxylated C12-14 alcohol (AE-07), sodium salt of sulfonated diphenyl ether tetrapropylene derivative (2A1), sodium allyl ether hydroxypropyl sulfonate, sodium dodecyl sulfate, and isomeric tridecyl alcohol polyoxyethylene (3) ether;

[0037] In one possible embodiment, the first emulsifier is 1 to 2 parts by weight;

[0038] In one possible embodiment, the second emulsifier is 3-14 parts by weight, preferably 7-13 parts by weight;

[0039] In one possible embodiment, the first oxidant, the second oxidant, and the third oxidant are each independently selected from one or more of ammonium persulfate, sodium persulfate, tert-butyl hydrogen peroxide, and hydrogen peroxide;

[0040] In one possible embodiment, the first oxidant is 0.5 to 4 parts by mass;

[0041] In one possible embodiment, the second oxidant is 1 to 4 parts by mass;

[0042] In one possible embodiment, the third oxidant is 0.5 to 4 parts by mass;

[0043] In one possible embodiment, in step 2, a portion of the pre-emulsion added to the reactor is 2% to 5% of the total mass of the pre-emulsion.

[0044] In one possible embodiment, the time to cool down to 55-75°C is ≤60 min;

[0045] In one possible embodiment, the time for adding the third oxidizing agent and reducing agent is 30-60 minutes.

[0046] Thirdly, the present invention provides an application of an aqueous acrylic metal pretreatment emulsion in metal pretreatment.

[0047] The product uses a large number of hydrophilic monomers, which are much higher than the hydrophilic monomer content (1-5%) in conventional acrylic metal pretreatment emulsions. These monomers, such as combinations of methacrylic acid, acrylic acid, and / or acrylamide, ensure the water solubility of the product's coating film. In addition, the methacrylic acid and acrylic monomers have higher self-polymerization activity and are distributed on the surface of the latex particles, providing production stability for the product. During the polymerization reaction, the homopolymerization activity of acrylamide is much greater than that of methacrylic acid and acrylic monomers, resulting in a more uniform distribution of acrylamide in the molecular chain segments. Due to the hydrophobicity of the molecular chain segments, most of the acrylamide is concentrated inside the latex particles. Since acrylamide contains hydrogen bonds, it provides the prerequisite for the subsequent water absorption and self-thickening of the latex particles and further increase in particle size.

[0048] In summary, this invention, through ingenious overall formulation and process design, produces an emulsion with low production and subsequent application costs, while also possessing excellent water solubility. It balances the relationship between product cost and performance, and avoids environmental pollution problems in subsequent applications, thus solving a difficult problem in the industry.

[0049] The technical solution of this invention has the following advantages:

[0050] 1. This invention provides an aqueous acrylic metal pretreatment emulsion, comprising, by weight, the following raw materials: 100-140 parts by weight of hard monomer; 120-170 parts by weight of soft monomer; 30-60 parts by weight of functional monomer; 5-15 parts by weight of emulsifier; 0.1-0.5 parts by weight of buffer; 1-8 parts by weight of oxidant; 0.1-0.5 parts by weight of reducing agent; 10-30 parts by weight of post-additional additives; and 600-680 parts by weight of water; wherein the functional monomer includes acrylamide, and the acrylamide accounts for 1.5%-26% of the total mass of the hard monomer, soft monomer, and functional monomer, preferably 8%-12%.

[0051] This invention utilizes a large amount of acrylamide, which exhibits high homopolymerization activity during the polymerization reaction, resulting in a relatively uniform distribution of acrylamide across the molecular chain segments. Due to the hydrophobicity of the polymer molecular chain segments, most of the acrylamide is concentrated within the latex particles. The presence of hydrogen bonds in acrylamide provides a prerequisite for subsequent water absorption and self-thickening of the latex particles, as well as further increase in particle size. The paint film obtained from the water-based acrylic metal pretreatment emulsion of this invention possesses excellent water solubility. The resin surface layer formed on the metal substrate using this invention can be directly washed away with water during further processing, thereby rapidly removing adhering oils and greases in a green, pollution-free, and thorough manner.

[0052] 2. The preparation method of the waterborne acrylic metal pretreated emulsion of the present invention includes the following steps: Step 1: Add deionized water to a reaction vessel, heat to 80-95℃, and add a first emulsifier to the bottom of the vessel; Step 2: At 80-95℃, add a portion of pre-emulsion and a first oxidant to the reaction vessel, and react for 10-30 minutes to obtain a seed emulsion; Step 3: Add the remaining pre-emulsion and a second oxidant dropwise to the seed emulsion, with a total dropwise addition time of 120-300 minutes; Step 4: After the dropwise addition is completed, keep the temperature at 80-95℃ until the viscosity reaches 5000-8000 cps and the particle size reaches 400-800 nm, then cool down to 55-75℃, and add a third oxidant and a reducing agent dropwise while cooling down. After cooling down to below 50℃, add the post-additional additives and adjust the pH to 3.0-6.5.

[0053] Under high-temperature conditions, the surface of latex particles becomes more porous. Therefore, at the end of the dripping stage, as the emulsion is kept at high temperature, water molecules migrate more easily into the interior of the latex particles. At the same time, because the hydrogen bonds contained in acrylamide make it easier to adsorb water, the amount of bound water inside the latex particles increases, and the latex particles become larger. As the particle size of the emulsion increases, the viscosity of the product also increases significantly. The final product has the characteristics of high viscosity and self-thickening. This allows the product to achieve high viscosity without the use of thickeners, even with low solids content and large particle size. The workability of the product is improved, balancing the relationship between product performance and cost. Detailed Implementation

[0054] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0055] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0056] In the following embodiments, portions are by weight unless otherwise specified.

[0057] Table 1. Raw materials used in the preparation of acrylic metal pretreated emulsions

[0058] Abbreviation Chemical types EHA Isooctyl acrylate (CNOOC - Industrial Grade) MMA Methyl methacrylate (Wanhua Chemical - Industrial Grade) LA 030H Isomeric tridecyl alcohol polyoxyethylene (3) ether (Solvay - Industrial Grade) 710 Polyoxyethylene polystyrene phenolic ether (Chūjīn Synthetic Chemicals - Industrial Grade) AM Acrylamide (Aisen - Industrial Grade) AA Acrylic acid (Wanhua Chemical - Industrial Grade) NaHCO3 Sodium bicarbonate (Shandong Haitian Biotechnology - Industrial Grade) APS Ammonium persulfate (United - Industrial Grade) T-BHP tert-butyl hydrogen peroxide (Jiangsu Qiangsheng - Industrial Grade) IAA Isoascorbic acid (Zhengzhou Tuoyang - Industrial Grade) Tego825 Defoamer from DIGIC (Evonik - Industrial Grade) MEA Ethanolamine (Xilong Chemical - Industrial Grade) Kordek MLX Preservatives (Dow - Industrial Grade) DIW Deionized water

[0059] Example 1

[0060] This embodiment provides a method for preparing an aqueous acrylic metal pretreated emulsion, comprising the following steps:

[0061] Pre-emulsion preparation: 160 parts deionized water (DIW), 2 parts polyoxyethylene polystyrene phenol ether (710), 5 parts isotridecyl alcohol polyoxyethylene (3) ether (LA 030H), 160 parts isooctyl acrylate (EHA), 120 parts methyl methacrylate (MMA), 32 parts acrylamide, 12 parts acrylic acid (AA), and 0.3 parts ammonium bicarbonate are prepared in a pre-emulsion kettle and stirred thoroughly.

[0062] Weigh 0.5 parts of ammonium persulfate (APS) and dissolve it in 10 parts of deionized water (DIW) to prepare a bottom oxidant solution; weigh 1.5 parts of ammonium persulfate (APS) and dissolve it in 30 parts of deionized water (DIW) to prepare a dropwise oxidant solution.

[0063] Add 380 parts of deionized water to the reactor and heat to 85°C. Add 1 part of polyoxyethylene polystyrene phenol ether 710 and then 10 parts of the prepared pre-emulsion. Add the bottom oxidant solution to the reactor. After 15 minutes, add the remaining pre-emulsion solution and the oxidant solution dropwise, controlling the reaction temperature at 85°C, until all the addition is completed. The dropwise addition time is 240 minutes. After the addition was completed, the temperature was kept at 80-95℃. The particle size and viscosity were monitored. After 4 hours of holding, the particle size increased to 500nm and the viscosity increased to 6000cp. The material in the reactor was then rapidly cooled to 60℃ over 20 minutes. 0.5 parts of tert-butyl hydroperoxide (TBHP) dissolved in 15 parts of deionized water (DIW) and 0.4 parts of isoascorbic acid (IAA) dissolved in 15 parts of deionized water (DIW) were added dropwise over 40 minutes. The temperature was then further reduced to 50℃. Then, 10 parts of MEA (ethanolamine) diluted in 10 parts of deionized water (DIW) were added for neutralization, along with 0.5 parts of defoamer Tego-825 and 5 parts of preservative Kordek MLX diluted in 5 parts of deionized water (DIW), to obtain emulsion 1-1.

[0064] Example 2

[0065] This embodiment provides a method for preparing an aqueous acrylic metal pretreated emulsion, comprising the following steps:

[0066] Pre-emulsion preparation: 160 parts deionized water (DIW), 2 parts polyoxyethylene polystyrene phenol ether 710, 5 parts isotridecyl alcohol polyoxyethylene (3) ether LA 030H, 170 parts isooctyl acrylate (EHA), 140 parts methyl methacrylate (MMA), 6 parts acrylamide, 8 parts acrylic acid (AA), and 0.3 parts ammonium bicarbonate are prepared in a pre-emulsion kettle and stirred thoroughly.

[0067] Weigh 0.5 parts of ammonium persulfate (APS) and dissolve it in 10 parts of deionized water (DIW) to prepare a bottom oxidant solution; weigh 1.5 parts of ammonium persulfate (APS) and dissolve it in 30 parts of deionized water (DIW) to prepare a dropwise oxidant solution.

[0068] Add 380 parts of deionized water to the reactor and heat to 85°C. Add 1 part of polyoxyethylene polystyrene phenol ether 710 and then 10 parts of the prepared pre-emulsion. Add the bottom oxidant solution to the reactor. After 15 minutes, add the remaining pre-emulsion solution and the oxidant solution dropwise, controlling the reaction temperature at 85°C, until all the addition is completed. The dropwise addition time is 240 minutes. After the addition was completed, the temperature was kept at 80-95℃. The particle size and viscosity were monitored. After 4 hours of holding, the particle size was 280nm and the viscosity increased to 3000cp. The material in the reactor was then rapidly cooled to 60℃ over 20 minutes. 0.5 parts of tert-butyl hydroperoxide (TBHP) dissolved in 15 parts of deionized water (DIW) and 0.4 parts of isoascorbic acid (IAA) dissolved in 15 parts of deionized water (DIW) were added dropwise over 40 minutes. The temperature was then further reduced to 50℃. Then, 10 parts of MEA diluted in 10 parts of deionized water (DIW) were added for neutralization, along with 0.5 parts of defoamer Tego-825 and 5 parts of preservative Kordek MLX diluted in 5 parts of deionized water (DIW), to obtain emulsion 1-2.

[0069] Example 3

[0070] This embodiment provides a method for preparing an aqueous acrylic metal pretreated emulsion, comprising the following steps:

[0071] Pre-emulsion preparation: 160 parts deionized water (DIW), 2 parts polyoxyethylene polystyrene phenol ether (710), 5 parts isotridecyl alcohol polyoxyethylene (3) ether (LA 030H), 120 parts isooctyl acrylate (EHA), 100 parts methyl methacrylate (MMA), 84 parts acrylamide, 20 parts acrylic acid (AA), and 0.3 parts ammonium bicarbonate are prepared in a pre-emulsion kettle and stirred thoroughly.

[0072] Weigh 0.5 parts of ammonium persulfate (APS) and dissolve it in 10 parts of deionized water (DIW) to prepare a bottom oxidant solution; weigh 1.5 parts of ammonium persulfate (APS) and dissolve it in 30 parts of deionized water (DIW) to prepare a dropwise oxidant solution.

[0073] Add 380 parts of deionized water to the reactor and heat to 85°C. Add 1 part of polyoxyethylene polystyrene phenol ether 710 and then 10 parts of the prepared pre-emulsion. Add the bottom oxidant solution to the reactor. After 15 minutes, add the remaining pre-emulsion solution and the oxidant solution dropwise, controlling the reaction temperature at 85°C, until all the addition is completed. The dropwise addition time is 240 minutes. After the addition was completed, the temperature was kept at 80-95℃. The particle size and viscosity were monitored. After 3 hours of holding, the particle size was 1000nm and the viscosity increased to 15000cps. The material in the reactor was then rapidly cooled to 60℃ over 20 minutes. 0.5 parts of tert-butyl hydroperoxide (TBHP) dissolved in 15 parts of deionized water (DIW) and 0.4 parts of isoascorbic acid (IAA) dissolved in 15 parts of deionized water (DIW) were added dropwise over 40 minutes. The temperature was then further reduced to 50℃. Then, 10 parts of MEA diluted in 10 parts of deionized water (DIW) were added for neutralization, along with 0.5 parts of defoamer Tego-825 and 5 parts of preservative Kordek MLX diluted in 5 parts of deionized water (DIW), to obtain emulsion 1-3.

[0074] Example 4

[0075] This embodiment provides a method for preparing an aqueous acrylic metal pretreated emulsion, comprising the following steps:

[0076] Pre-emulsion preparation: 160 parts deionized water (DIW), 2 parts polyoxyethylene polystyrene phenol ether (710), 5 parts isotridecyl alcohol polyoxyethylene (3) ether (LA 030H), 160 parts isooctyl acrylate (EHA), 120 parts methyl methacrylate (MMA), 32 parts acrylamide, 12 parts acrylic acid (AA), and 0.3 parts ammonium bicarbonate are prepared in a pre-emulsion kettle and stirred thoroughly.

[0077] Weigh 0.5 parts of ammonium persulfate (APS) and dissolve it in 10 parts of deionized water (DIW) to prepare a bottom oxidant solution; weigh 1.5 parts of ammonium persulfate (APS) and dissolve it in 30 parts of deionized water (DIW) to prepare a dropwise oxidant solution.

[0078] Add 380 parts of deionized water to the reactor and heat to 85°C. Add 1 part of polyoxyethylene polystyrene phenol ether 710 and then 10 parts of the prepared pre-emulsion. Add the bottom oxidant solution to the reactor. After 15 minutes, add the remaining pre-emulsion solution and the oxidant solution dropwise, controlling the reaction temperature at 85°C, until all the addition is completed. The dropwise addition time is 240 minutes. After the addition was completed, the temperature was kept at 80-95℃. The particle size and viscosity were monitored. After 8 hours of holding, the particle size increased to 1200nm and the viscosity increased to 17000cps. The material in the reactor was then rapidly cooled to 60℃ over 20 minutes. 0.5 parts of tert-butyl hydroperoxide (TBHP) dissolved in 15 parts of deionized water (DIW) and 0.4 parts of isoascorbic acid (IAA) dissolved in 15 parts of deionized water (DIW) were added dropwise over 40 minutes. The temperature was then further reduced to 50℃. Then, 10 parts of MEA diluted in 10 parts of deionized water (DIW) were added for neutralization, along with 0.5 parts of defoamer Tego-825 and 5 parts of preservative Kordek MLX diluted in 5 parts of deionized water (DIW), to obtain emulsion 1-4.

[0079] Example 5

[0080] This embodiment provides a method for preparing an aqueous acrylic metal pretreated emulsion, comprising the following steps:

[0081] Pre-emulsion preparation: 160 parts deionized water (DIW), 2 parts polyoxyethylene polystyrene phenol ether (710), 5 parts isotridecyl alcohol polyoxyethylene (3) ether (LA 030H), 160 parts isooctyl acrylate (EHA), 120 parts methyl methacrylate (MMA), 32 parts acrylamide, 12 parts acrylic acid (AA), and 0.3 parts ammonium bicarbonate are prepared in a pre-emulsion kettle and stirred thoroughly.

[0082] Weigh 0.5 parts of ammonium persulfate (APS) and dissolve it in 10 parts of deionized water (DIW) to prepare a bottom oxidant solution; weigh 1.5 parts of ammonium persulfate (APS) and dissolve it in 30 parts of deionized water (DIW) to prepare a dropwise oxidant solution.

[0083] Add 380 parts of deionized water to the reactor and heat to 85°C. Add 1 part of polyoxyethylene polystyrene phenol ether 710 and then 10 parts of the prepared pre-emulsion. Add the bottom oxidant solution to the reactor. After 15 minutes, add the remaining pre-emulsion solution and the oxidant solution dropwise, controlling the reaction temperature at 85°C, until all the addition is completed. The dropwise addition time is 240 minutes. After the addition was completed, the temperature was kept at 80-95℃. The particle size and viscosity were monitored. After 1 hour of holding, the particle size increased to 300nm and the viscosity increased to 4000cps. The material in the reactor was then rapidly cooled to 60℃ over 20 minutes. 0.5 parts of tert-butyl hydroperoxide (TBHP) dissolved in 15 parts of deionized water (DIW) and 0.4 parts of isoascorbic acid (IAA) dissolved in 15 parts of deionized water (DIW) were added dropwise over 40 minutes. The temperature was then further reduced to 50℃. Then, 10 parts of MEA diluted in 10 parts of deionized water (DIW) were added for neutralization, along with 0.5 parts of defoamer Tego-825 and 5 parts of preservative Kordek MLX diluted in 5 parts of deionized water (DIW), to obtain emulsion 1-5.

[0084] Example 6

[0085] This embodiment provides a method for preparing an aqueous acrylic metal pretreated emulsion, comprising the following steps:

[0086] Pre-emulsion preparation: 160 parts deionized water (DIW), 7 parts sodium dodecyl sulfate (SDS), 160 parts isooctyl acrylate (EHA), 120 parts methyl methacrylate (MMA), 32 parts acrylamide, 12 parts acrylic acid (AA), and 0.3 parts ammonium bicarbonate are prepared in a pre-emulsion tank and stirred thoroughly.

[0087] Weigh 0.5 parts of ammonium persulfate (APS) and dissolve it in 10 parts of deionized water (DIW) to prepare a bottom oxidant solution; weigh 1.5 parts of ammonium persulfate (APS) and dissolve it in 30 parts of deionized water (DIW) to prepare a dropwise oxidant solution.

[0088] Add 380 parts of deionized water to the reactor and heat to 85°C. Add 1 part of sodium dodecyl sulfate (SDS) and then 10 parts of the prepared pre-emulsion. Add the bottom oxidant solution to the reactor. After 15 minutes, add the remaining pre-emulsion solution and the oxidant solution dropwise, controlling the reaction temperature at 85°C, until all the addition is completed. The dropwise addition time is 240 minutes. After the addition was completed, the temperature was kept at 80-95℃. The particle size and viscosity were monitored. After 4 hours of holding, the particle size increased to 400nm and the viscosity increased to 5000cp. The material in the reactor was then rapidly cooled to 60℃ over 20 minutes. 0.5 parts of tert-butyl hydroperoxide (TBHP) dissolved in 15 parts of deionized water (DIW) and 0.4 parts of isoascorbic acid (IAA) dissolved in 15 parts of deionized water (DIW) were added dropwise over 40 minutes. The temperature was then further reduced to 50℃. Then, 10 parts of MEA diluted in 10 parts of deionized water (DIW) were added for neutralization, along with 0.5 parts of defoamer Tego-825 and 5 parts of preservative Kordek MLX diluted in 5 parts of deionized water (DIW), to obtain emulsion 1-6.

[0089] Comparative Example 1

[0090] This comparative example provides a method for preparing a metal pretreated emulsion, comprising the following steps:

[0091] Pre-emulsion preparation: 160 parts deionized water (DIW), 6 parts sodium dodecyl sulfate (SDS), 160 parts isooctyl acrylate (EHA), 120 parts methyl methacrylate (MMA), 34 parts styrene, 4 parts acrylic acid (AA), and 6 parts methacrylic acid are prepared in a pre-emulsion kettle and stirred thoroughly.

[0092] Weigh 0.5 parts of ammonium persulfate (APS) and dissolve it in 10 parts of deionized water (DIW) to prepare a bottom oxidant solution; weigh 1.5 parts of ammonium persulfate (APS) and dissolve it in 30 parts of deionized water (DIW) to prepare a dropwise oxidant solution.

[0093] Add 380 parts of deionized water to the reactor and heat to 85°C. Add 2 parts of sodium dodecyl sulfate (SDS) and then 10 parts of the prepared pre-emulsion. Add the bottom oxidant solution to the reactor. After 15 minutes, add the remaining pre-emulsion solution and the oxidant solution dropwise, controlling the reaction temperature at 85°C, until all the addition is completed. The dropwise addition time is 240 minutes. After the addition is complete, maintain the temperature at 80-95℃ for 45 minutes. Then, rapidly reduce the temperature of the material in the reactor to 60℃ over 20 minutes. Add 0.5 parts of tert-butyl hydroperoxide (TBHP) dissolved in 15 parts of deionized water (DIW) and 0.4 parts of isoascorbic acid (IAA) dissolved in 15 parts of deionized water (DIW) over 40 minutes. Reduce the temperature to 50℃, then add 10 parts of MEA diluted in 10 parts of deionized water (DIW) for neutralization, 0.5 parts of defoamer Tego-825, and 5 parts of preservative Kordek MLX diluted in 5 parts of deionized water (DIW) to obtain conventional pretreatment emulsion-1.

[0094] Comparative Example 2

[0095] This comparative example provides a method for preparing a metal pretreated emulsion, comprising the following steps:

[0096] Pre-emulsion preparation: 160 parts deionized water (DIW), 5 parts sodium dodecyl sulfate (SDS), 160 parts isooctyl acrylate (EHA), 120 parts methyl methacrylate (MMA), 40 parts butyl acrylate, and 4 parts AA are prepared in a pre-emulsion kettle and stirred thoroughly.

[0097] Weigh 0.5 parts of ammonium persulfate (APS) and dissolve it in 10 parts of deionized water (DIW) to prepare a bottom oxidant solution; weigh 1.5 parts of ammonium persulfate (APS) and dissolve it in 30 parts of deionized water (DIW) to prepare a dropwise oxidant solution.

[0098] Add 380 parts of deionized water to the reactor and heat to 85°C. Add 1 part of sodium dodecyl sulfate (SDS) and then 10 parts of the prepared pre-emulsion. Add the bottom oxidant solution to the reactor. After 15 minutes, add the remaining pre-emulsion solution and the oxidant solution dropwise, controlling the reaction temperature at 85°C, until all the addition is completed. The dropwise addition time is 240 minutes. After the addition is complete, maintain the temperature at 80-95℃ for 3 hours. Then, rapidly reduce the temperature of the material in the reactor to 60℃ over 20 minutes. Add 0.5 parts of tert-butyl hydroperoxide (TBHP) dissolved in 15 parts of deionized water (DIW) and 0.4 parts of isoascorbic acid (IAA) dissolved in 15 parts of deionized water (DIW) over 40 minutes. Reduce the temperature to 50℃, then add 10 parts of MEA diluted in 10 parts of deionized water (DIW) for neutralization, along with 0.5 parts of defoamer Tego-825 and 5 parts of preservative Kordek MLX diluted in 5 parts of deionized water (DIW) to obtain conventional pretreated emulsion-2.

[0099] The metal pretreatment emulsions prepared in the above embodiments and comparative examples were tested according to the following standards:

[0100] Adhesion test standard: Apply a 100μm thick metal pretreatment emulsion to a metal substrate, dry it at 120℃, fold the metal substrate in half and break it, and test the width of the paint film peeling off. The smaller the width, the better the adhesion. ≤2mm means that the adhesion of the test film to the substrate is qualified.

[0101] Water solubility test standard: Coat a 100μm thick layer of emulsion on a metal substrate, dry it at 120℃, drop a drop of water on the film, spread the water by hand and wipe the surface of the film, and record its dissolution time.

[0102] Workability test standard: Roll a layer of emulsion onto a metal substrate, then hang the substrate upside down and observe the sagging phenomenon on the surface of the film. The film is characterized by a score of 1-10, with higher scores indicating better workability.

[0103] Particle size: Determined using a Malvern ZS90 particle size analyzer, employing a polystyrene latex model, with water as the dispersion medium, and using general purpose analytical methods.

[0104] Viscosity: Measured using Brookfield LV64#60r and 64#30r.

[0105] Table 2 Experimental conditions and emulsion indices for the examples and comparative examples

[0106]

[0107] Table 3 Comparison of Emulsion Performance Tests

[0108] Water-soluble Adhesion Constructability ≤2mm ≥5 points Example 1 1s 0.5 10 Example 2 5s 3 7 Example 3 1.5s 0.6 5 Example 4 0.9s 0.5 6 Example 5 0.9s 0.6 6 Example 6 1.5s 0.5 7 Comparative Example 1 >10min 6 4 Comparative Example 2 >10min 5 4

[0109] As shown in Table 3, the emulsions prepared in Examples 1-6 of this invention exhibit significantly improved water solubility compared to Comparative Examples 1 and 2. This means that the resin surface layer formed on the metal substrate using this invention can be directly washed away with water during deep processing, thereby quickly removing attached oils and greases in a green, pollution-free, and thorough manner. Simultaneously, the adhesion and workability of the emulsions of this invention are also significantly improved.

[0110] A comparison of Examples 1 with Examples 2 and 3 shows that when acrylamide accounts for 8% to 12% of the total mass of hard monomers, soft monomers, and functional monomers, the resulting water-based acrylic metal pretreated emulsion exhibits superior water solubility and adhesion.

[0111] A comparison of Examples 1 with Examples 4 and 5 shows that when the heat preservation time after dripping is within 3 to 5 hours, the resulting acrylic metal pretreated emulsion exhibits superior workability.

[0112] A comparison of Example 1 and Example 6 shows that the acrylic metal pretreatment emulsion obtained by using polyoxyethylene polystyrene phenol ether 710 and isomeric tridecyl alcohol polyoxyethylene (3) ether LA 030H as emulsifiers has better water solubility and workability.

[0113] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. An aqueous acrylic metal pretreatment emulsion, characterized in that, By weight, the raw materials include: The functional monomer includes acrylamide, which accounts for 1.5% to 26% of the total mass of the hard monomer, soft monomer and functional monomer, preferably 8% to 12%.

2. The aqueous acrylic metal pretreatment emulsion according to claim 1, characterized in that, At least one of the following conditions must be met: (5) 0.2-0.4 parts by weight of buffer; (6) Oxidizing agent 2-4 parts by weight; (7) 0.2-0.4 parts by weight of reducing agent; (8) Add 15-25 parts by weight of the auxiliary agent afterward; (9) 620-680 parts by weight of water; (10) The waterborne acrylic metal pretreated emulsion has a solid content of 33wt%-35wt% by mass; (11) The particle size of the latex particles in the aqueous acrylic metal pretreated emulsion is 200-1500 nm, preferably 400-800 nm; (12) The viscosity of the aqueous acrylic metal pretreatment emulsion is 3000-18000 cps, preferably 5000-10000 cps, and more preferably 5000-8000 cps.

3. The aqueous acrylic metal pretreated emulsion according to claim 1 or 2, characterized in that, At least one of the following conditions must be met: (1) The hard monomers include one or more of butyl methacrylate, methyl methacrylate, and styrene; Preferably, the hard monomer is selected from a combination containing methyl methacrylate and / or butyl methacrylate monomers; (2) The soft monomers include one or more of isooctyl acrylate, butyl acrylate, and ethyl acrylate; (3) The functional monomers also include one or more of methyl diacetone acrylamide, hydroxyethyl acrylate, methacrylic acid, and acrylic acid.

4. The aqueous acrylic metal pretreated emulsion according to claim 1 or 2, characterized in that, The emulsifier includes one or more of the following: sodium allyl oxypropanesulfonate, sodium dodecyl diphenyl ether disulfonate, polyoxyethylene polystyrene phenolic ether, sodium tridecyl alcohol polyoxyethylene ether sulfate, ethoxylated alcohol, sodium salt of sulfonated diphenyl ether tetrapropylene derivative, sodium allyl ether hydroxypropyl sulfonate, sodium dodecyl sulfate, and isomeric tridecyl alcohol polyoxyethylene ether. Preferably, the emulsifier includes one or more of isotridecyl alcohol polyoxyethylene ether, ethoxylated alcohol, and polyoxyethylene polystyrene phenolic ether.

5. The aqueous acrylic metal pretreated emulsion according to claim 1 or 2, characterized in that, At least one of the following conditions must be met: (1) The buffer includes one or more of sodium bicarbonate, sodium carbonate, and ammonium bicarbonate; (2) The oxidant includes one or more of ammonium persulfate, sodium persulfate, tert-butyl hydrogen peroxide, and hydrogen peroxide; (3) The reducing agent includes one or more of sodium metabisulfite, isoascorbic acid, sodium hydrosulfite, sodium formaldehyde sulfoxylate, and FF6; (4) The added additives include at least one of neutralizing agents, defoamers, and preservatives.

6. A method for preparing the aqueous acrylic metal pretreated emulsion according to any one of claims 1-5, characterized in that, Includes the following steps: Step 1: Add deionized water to the reactor, heat to 80-95℃, and add the first emulsifier to the bottom of the reactor; Step 2: At 80-95℃, add a portion of the pre-emulsion and the first oxidant to the reactor and react for 10-30 minutes to obtain the seed emulsion; Step 3: Add the remaining pre-emulsion and the second oxidant to the seed emulsion dropwise over a total time of 120-300 min. Step 4: After the addition is complete, keep the temperature at 80-95℃, then cool it down to 55-75℃. Add the third oxidizing agent and reducing agent at 55-75℃, and continue to cool down to below 50℃. Add the additives after adding the third oxidizing agent to obtain the water-based acrylic metal pretreated emulsion.

7. The method for preparing the aqueous acrylic metal pretreated emulsion according to claim 6, characterized in that, In step 4, the temperature is maintained at 80-95℃ for 1-8 hours; preferably, it is maintained for 3-5 hours. or In step 4, while maintaining the temperature at 80-95℃, the viscosity and particle size of the emulsion are monitored. After the viscosity reaches 3000-18000cps and the particle size reaches 200-1500nm, the temperature is lowered. Preferably, the temperature is lowered after the viscosity reaches 5000-8000cps and the particle size reaches 400-800nm.

8. The method for preparing the aqueous acrylic metal pretreated emulsion according to claim 6 or 7, characterized in that, The pre-emulsion comprises hard monomers, soft monomers, functional monomers, a second emulsifier, a buffer, and deionized water.

9. The method for preparing the aqueous acrylic metal pretreated emulsion according to claim 8, characterized in that, At least one of the following conditions must be met: (1) The first emulsifier and the second emulsifier are independently selected from any one or more of allyloxyhydroxypropanesulfonate, sodium dodecyl diphenyl ether disulfonate, polyoxyethylene polystyrene phenolic ether, sodium tridecyl alcohol polyoxyethylene ether sulfate, ethoxylated C12-14 alcohol, sodium salt of sulfonated diphenyl ether tetrapropylene derivative, allyl ether hydroxypropyl sulfonate, sodium dodecyl sulfate, and isomeric tridecyl alcohol polyoxyethylene ether. (2) The first emulsifier is 1 to 2 parts by weight; (3) The second emulsifier is 3-14 parts by weight, preferably 7-13 parts by weight; (4) The first oxidant, the second oxidant and the third oxidant are each independently selected from one or more of ammonium persulfate, sodium persulfate, tert-butyl hydrogen peroxide and hydrogen peroxide; (5) The first oxidant is 0.5 to 4 parts by mass; (6) The second oxidant is 1 to 4 parts by mass; (7) The third oxidizing agent is 0.5 to 4 parts by mass; (8) In step 2, the portion of the pre-emulsion added to the reactor is 2% to 5% of the total mass of the pre-emulsion.

10. The use of an aqueous acrylic metal pretreatment emulsion according to any one of claims 1 to 5 or an aqueous acrylic metal pretreatment emulsion prepared by any one of claims 6 to 9 in metal pretreatment.

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