A kind of acrylic cathode electrophoretic coating original paint and its preparation method and application

Abstract

This invention provides an acrylic cathodic electrophoretic coating primer, its preparation method, and its application. The raw materials for preparing the acrylic cathodic electrophoretic coating primer include the following components by weight: 3-7 parts modified epoxy resin prepolymer, 5-20 parts acrylate monomers containing tertiary amine groups, 8-30 parts acrylate monomers containing hydroxyl groups, 30-40 parts styrene, 1-10 parts isooctyl acrylate, 0.2-0.6 parts surfactant, 1-10 parts crosslinking monomer, 10-30 parts solvent A, 0.5-1.5 parts initiator, and 10-30 parts low-temperature curing agent; the crosslinking monomer includes vinyloxazoline and unsaturated ammonium carboxylate. The electrophoretic coating containing the acrylic cathodic electrophoretic coating primer provided by this invention exhibits good stability, and the electrophoretic coating made from it has the characteristics of good sweat resistance, salt spray resistance, and high hardness.

Description

Technical Field

[0001] The invention belongs to the technical field of electrophoretic coatings, and in particular relates to an acrylic cathode electrophoretic coating original paint and a preparation method and application thereof. Background Art

[0002] Polymer coatings are widely used in various industries including automotive, electronics, infrastructure and medical industries to improve the service life of products. Cathodic electrodeposition (CED) provides a breakthrough technology that has significant advantages over traditional coating methods in that it can provide faster and more uniform coatings with excellent corrosion resistance, the ability to coat irregular surfaces and less material loss. In addition, CED can use coatings with water-soluble resin systems, has no VOC emissions, and is environmentally friendly.

[0003] In the field of electroplated mirror frames, due to the long-term contact between the coating and human skin, it is easy to be corroded by the sweat secreted by the human body, resulting in plating loss and rust, which in turn affects skin health. Therefore, there are high requirements for the sweat resistance of the coating. In the prior art, electrophoretic coatings will undergo stratification and precipitation after being stored for a certain period of time, affecting their use, and the storage time of electrophoretic coatings in the manufacturing system is relatively long, so electrophoretic coatings with high storage stability are needed to meet market demand. In the prior art, compared with solvent-based electrophoretic coatings, water-based electrophoretic coatings have poor storage stability, especially when the amount used on the production site is low. In addition, the artificial sweat resistance test of electrophoretic coatings on the current market is generally only 24 hours, and the continuous use time in the electrophoretic tank is relatively short, generally not more than two weeks, and the conventional blocked isocyanate curing agent commonly used in electrophoretic coatings can only release -NCO to react with hydroxyl groups at 160~180℃, and the preparation process consumes a lot of energy, which is not conducive to energy saving.

[0004] CN115819681A discloses a phosphate modified resin, a preparation method thereof and a cathode electrophoretic coating, wherein the phosphate modified resin is polymerized from the following raw materials by weight: 52-67 parts of a carboxyl-free acrylate monomer, 2-3 parts of an acrylic acid end group polyphosphate, 18-35 parts of a first alcohol ether solvent, 3-4 parts of a first initiator, 2.5-4.5 parts of a second initiator and 4-5 parts of an aminating agent. The cathode electrophoretic coating prepared from the phosphate modified resin provided by the technical solution is not only suitable for various metal coatings, but also has excellent resistance to artificial sweat, but the acrylic acid end group polyphosphate used is a phosphorus-containing compound, which is easy to cause phosphorus pollution to the water environment.

[0005] Therefore, there is an urgent need to develop an electrophoretic coating with good stability, energy-saving and environmentally friendly preparation process, and sweat-resistant electrophoretic coating. Summary of the invention

[0006] In view of the shortcomings of the prior art, the present invention aims to provide an acrylic cathode electrophoretic coating original paint and a preparation method and application thereof. The electrophoretic coating comprising the acrylic cathode electrophoretic coating original paint has good stability, and the electrophoretic coating prepared therefrom has the characteristics of good sweat resistance, good salt spray resistance and high hardness.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides an acrylic cathode electrophoretic coating original paint, wherein the raw materials for preparing the acrylic cathode electrophoretic coating original paint include the following components in parts by weight: 3 to 7 parts (for example, 3.5 parts, 4 parts, 4.5 parts, 5 parts, 5.5 parts, 6 parts or 6.5 parts, etc.) of a modified epoxy resin prepolymer, 5 to 20 parts (for example, 7 parts, 9 parts, 11 parts, 13 parts, 15 parts, 17 parts or 19 parts, etc.) of an acrylate monomer containing a tertiary amine group, 8 to 30 parts (for example, 10 parts, 12 parts, 14 parts, 16 parts, 18 parts, 20 parts) of a hydroxyl-containing acrylate monomer, and 10 to 30 parts (for example, 11 parts, 13 parts, 15 parts, 17 parts or 19 parts, etc.) of a hydroxyl-containing acrylate monomer. , 22 parts, 24 parts, 26 parts or 28 parts, etc.), styrene 30-40 parts (for example, 31 parts, 32 parts, 33 parts, 34 parts, 35 parts, 36 parts, 37 parts, 38 parts or 39 parts, etc.), 2-6 parts of isooctyl acrylate (for example, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, 5 parts or 5.5 parts, etc.), surfactant 0.2-0.6 parts (for example, 0.25 parts, 0.3 parts, 0.35 parts, 0.4 parts, 0.45 parts, 0.5 parts or 0.55 parts, etc.), cross-linking monomer 1-10 parts (for example, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h or 9 h, etc.), solvent A 10-30 parts (for example, 12 parts, 14 parts, 16 parts, 18 parts, 20 parts, 22 parts, 24 parts, 26 parts or 28 parts, etc.), initiator 0.5-1.5 parts (for example, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, 1.0 parts, 1.1 parts, 1.2 parts, 1.3 parts or 1.4 parts, etc.) and low temperature curing agent 10-30 parts (for example, 12 parts, 14 parts, 16 parts, 18 parts, 20 parts, 22 parts, 24 parts, 26 parts or 28 parts, etc.).

[0009] The crosslinking monomers include vinyl oxazoline and unsaturated carboxylic acid ammonium salts.

[0010] In the present invention, the modified epoxy resin prepolymer in the raw material for preparing the acrylic cathode electrophoretic coating can introduce epoxy groups into the polyacrylate molecular chain, thereby introducing a large number of secondary hydroxyl groups, and preparing the acrylic cathode electrophoretic coating raw paint that can significantly improve the adhesion and hardness of the electrophoretic coating, thereby greatly improving the sweat resistance of the electrophoretic coating prepared by the electrophoretic coating containing the acrylic cathode electrophoretic coating raw paint; the surfactant in the raw material for preparing the acrylic cathode electrophoretic coating raw paint has an emulsifying effect, which can improve the stability of the electrophoretic coating; the vinyl oxazoline and the unsaturated carboxylic acid ammonium salt enable the electrophoretic coating to undergo film formation by electrophoresis, and as the baking temperature increases, the structure formed by the unsaturated carboxylic acid ammonium salt on the polyacrylate molecular chain undergoes deamination, and the generated carboxyl group reacts with the oxazoline group, thereby further increasing the crosslinking points, improving the film density, and improving the performance of the electrophoretic coating; the low-temperature curing agent has a low curing temperature, so that the temperature required for the film formation and baking process of the electrophoretic coating is low and the energy consumption is low. The acrylic cathodic electrophoretic coating original paint and the electrophoretic coating prepared therefrom are environmentally friendly, energy-saving and have good stability. They can be stored at room temperature for more than half a year, and the electrophoretic tank liquid can be used continuously for more than 15 days.

[0011] Preferably, the modified epoxy resin prepolymer is prepared by the following method: an organic amine, an epoxy resin and a solvent B are mixed and reacted to obtain the modified epoxy resin prepolymer.

[0012] Preferably, the mass ratio of the organic amine to the epoxy resin is 1:(2.5-3.3), for example, 1:2.6, 1:2.7, 1:2.8, 1:2.9, 1:3.0, 1:3.1 or 1:3.2, etc.

[0013] It should be noted that those skilled in the art can reasonably adjust the mass ratio of the organic amine and the epoxy resin according to the specific types of the organic amine and the epoxy resin, so as to achieve the purpose of preparing a modified epoxy resin prepolymer with a certain molecular weight without excessive crosslinking.

[0014] Preferably, the mass ratio of the solvent B to the epoxy resin is 1:(3-5).

[0015] In the present invention, the mass ratio of the solvent B to the epoxy resin is preferably 1:(3-5), which can effectively reduce the viscosity of the system, ensure the uniformity of dispersion of the organic amine and the epoxy resin, and facilitate the smooth progress of the reaction.

[0016] Preferably, the organic amine comprises octylamine.

[0017] Preferably, the solvent B includes any one of n-butanol, isopropanol, ethylene glycol butyl ether, propylene glycol methyl ether or propylene glycol butyl ether, or a combination of at least two thereof.

[0018] Preferably, the mixing of the organic amine, the epoxy resin and the solvent B specifically comprises dropping the mixture of the epoxy resin and the solvent B into the organic amine for mixing.

[0019] Preferably, the dropping time is 2 to 3 h, for example, 2.1 h, 2.2 h, 2.3 h, 2.4 h, 2.5 h, 2.6 h, 2.7 h, 2.8 h or 2.9 h, etc.

[0020] Preferably, the reaction temperature is 75-80°C (e.g., 75.5°C, 76°C, 76.5°C, 77°C, 77.5°C, 78°C, 78.5°C, 79°C or 79.5°C, etc.), and the reaction time is 1-2 h (e.g., 1.1 h, 1.2 h, 1.3 h, 1.4 h, 1.5 h, 1.6 h, 1.7 h, 1.8 h or 1.9 h, etc.).

[0021] Preferably, the tertiary amine group-containing acrylate monomer includes dimethylaminoethyl methacrylate (DMAEMA).

[0022] Preferably, the hydroxyl-containing acrylate monomer includes any one of hydroxypropyl methacrylate (HPMA), hydroxypropyl acrylate (HPA), hydroxyethyl methacrylate (HEMA) or hydroxyethyl acrylate (HEA), or a combination of at least two thereof.

[0023] Preferably, the surfactant comprises polypropylene glycol diacrylate.

[0024] In the present invention, the polypropylene glycol diacrylate has the effect of reducing surface tension, can improve wettability to the substrate, and increase adhesion; at the same time, the double bonds contained therein can increase the crosslinking density of the electrophoretic coating, and improve scratch resistance and solvent resistance.

[0025] Preferably, the polypropylene glycol diacrylate includes polypropylene glycol (200) diacrylate.

[0026] Preferably, the vinyl oxazoline comprises 2-vinyl-2-oxazoline.

[0027] Preferably, the unsaturated carboxylic acid ammonium salt comprises ammonium acrylate.

[0028] Preferably, the weight proportion of vinyl oxazoline in the raw materials for preparing the acrylic cathodic electrophoretic coating is 0.5 to 5 parts (e.g., 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts or 4.5 parts, etc.), and more preferably 2 to 3 parts.

[0029] Preferably, the weight proportion of the unsaturated carboxylic acid ammonium salt in the raw materials for preparing the acrylic cathodic electrophoretic coating is 0.5 to 5 parts (e.g., 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts or 4.5 parts, etc.), and more preferably 2 to 3 parts.

[0030] Preferably, the mass ratio of the vinyl oxazoline to the unsaturated carboxylic acid ammonium salt is 1:(0.8-1.2).

[0031] In the present invention, illustratively, the vinyl oxazoline is 2-vinyl-2-oxazoline, the unsaturated carboxylic acid ammonium salt is ammonium acrylate, the electrophoretic coating comprising the original acrylic cathode electrophoretic coating paint of the present invention is heated after electrophoresis film formation, and the reaction of the oxazoline group introduced by 2-vinyl-2-oxazoline on the polymer molecular chain and the carboxylic acid ammonium salt group introduced by ammonium acrylate is as shown in Formula I, the carboxylic acid ammonium salt group on the polymer molecular chain undergoes deamination to form a carboxyl group and then reacts with the oxazoline group to produce crosslinking, thereby increasing the crosslinking points.

[0032] Formula I.

[0033] In formula 1, Represents the polymer molecular chain formed by the reaction of various components in the original paint of acrylic cathodic electrophoretic coating.

[0034] Preferably, the solvent A includes any one of n-butanol, isopropanol, ethylene glycol butyl ether, propylene glycol methyl ether or propylene glycol butyl ether, or a combination of at least two thereof.

[0035] Preferably, the initiator comprises azobisisobutyronitrile.

[0036] Preferably, the low temperature curing agent includes a blocked isocyanate curing agent and an amine curing agent.

[0037] Preferably, the mass ratio of the blocked isocyanate curing agent to the amine curing agent is 1:(0.5-1), for example, 1:0.55, 1:0.6, 1:0.65, 1:0.7, 1:0.75, 1:0.8, 1:0.85, 1:0.9 or 1:0.95, etc.

[0038] Preferably, the blocked isocyanate curing agent includes isophorone diisocyanate deblocked at 80-90°C (eg, 81°C, 82°C, 83°C, 84°C, 85°C, 86°C, 87°C, 88°C or 89°C, etc.).

[0039] Preferably, the amine curing agent includes isophoronediamine.

[0040] Preferably, the acrylic cathodic electrophoretic coating original paint further includes a neutralizer and / or a leveling agent.

[0041] Preferably, the weight proportion of the neutralizer in the raw materials for preparing the acrylic cathodic electrophoretic coating is 1 to 5 parts, for example, 1.5 parts, 2.0 parts, 2.5 parts, 3.0 parts, 3.5 parts, 4.0 parts or 4.5 parts.

[0042] Preferably, the neutralizing agent comprises a weak acid.

[0043] It should be noted that, in the present invention, the neutralizing agent is a commonly used weak acid, which refers to an acid having an ionization constant (Ka) less than 0.0001 (acidity coefficient pKa greater than 4), including but not limited to lactic acid and / or acetic acid.

[0044] Preferably, the weight proportion of the leveling agent in the raw materials for preparing the acrylic cathodic electrophoretic coating is 0.5-0.8 parts, for example, 0.53 parts, 0.56 parts, 0.59 parts, 0.62 parts, 0.65 parts, 0.68 parts, 0.71 parts, 0.74 parts or 0.77 parts, etc.

[0045] In a second aspect, the present invention provides a method for preparing the acrylic cathodic electrophoretic coating original paint as described in the first aspect, the preparation method comprising the following steps:

[0046] (1) mixing a tertiary amine-containing acrylic ester monomer, a hydroxyl-containing acrylic ester monomer, styrene, isooctyl acrylate, a surfactant, vinyl oxazoline, an unsaturated carboxylic acid ammonium salt and a portion of an initiator to obtain a monomer mixture;

[0047] (2) The monomer mixture obtained in step (1), the modified epoxy resin prepolymer, the solvent A, and the remaining initiator are mixed for reflux reaction, and a low-temperature curing agent is added to the mixture to obtain the acrylic cathode electrophoretic coating original paint.

[0048] It should be noted that, in the preparation reaction process of the acrylic cathodic electrophoretic coating original paint, the ammonia produced by the reaction will be continuously condensed and refluxed with the solvent A, so that the vinyl oxazoline and the unsaturated carboxylic acid ammonium salt will not undergo a large degree of cross-linking reaction.

[0049] Preferably, the step (2) specifically comprises the following steps: mixing the modified epoxy resin prepolymer and the solvent A, raising the temperature to 110-115°C (e.g., 111°C, 112°C, 113°C or 114°C), dripping the monomer mixture obtained in the step (1) to carry out a first heat preservation reflux reaction, the dripping time is 3-5 h (e.g., 3.2 h, 3.4 h, 3.6 h, 3.8 h, 4.0 h, 4.2 h, 4.4 h, 4.6 h or 4.8 h), and then adding the remaining initiator to carry out a second heat preservation reflux reaction for 1-2 h (e.g., 1.1 h, 1.2 h, 1.3 h, 1.4 h, 1.5 h, 1.6 h, 1.7 h, 1.8 h or 1.9 h). h, etc.), cool to 70-80°C (for example, 71°C, 72°C, 73°C, 74°C, 75°C, 76°C, 77°C, 78°C or 79°C), add low-temperature curing agent, neutralizing agent and leveling agent, and stir and mix for 20-30 min (for example, 21 min, 22 min, 23 min, 24 min, 25 min, 26 min, 27min, 28 min or 29 min, etc.) to obtain the acrylic cathodic electrophoretic coating original paint.

[0050] In the present invention, the time of the first heat preservation reflux reaction is the same as the time of dropwise adding the monomer mixture prepared in step (1).

[0051] Preferably, the dripping speed is controlled by a peristaltic pump.

[0052] It should be noted that the present invention uses a peristaltic pump to control the dripping speed, which helps to control the polymerization reaction speed, ensure the smooth progress of the reaction, and slowly transport the monomer mixture prepared in step (1) to the reaction system.

[0053] Preferably, based on the total weight of the initiator as 100%, the weight of the initiator of the portion is 70% to 85%, for example, 72%, 74%, 76%, 78%, 80%, 82% or 84%.

[0054] Preferably, the adding of the remaining initiator specifically comprises adding the remaining initiator in 2 to 3 times during the second insulation reflux reaction, and the time interval between each addition is 0.4 to 0.6 h (for example, 0.42 h, 0.44 h, 0.46 h, 0.48 h, 0.50 h, 0.52 h, 0.54 h, 0.56 h or 0.58 h, etc.).

[0055] It should be noted that the number of times and time intervals for adding the remaining initiator in the heat preservation reaction in step (2) of the present invention can be adjusted by those skilled in the art according to the monomer conversion rate to ensure sufficient reaction.

[0056] In a third aspect, the present invention provides an electrophoretic coating, which comprises water and the acrylic cathodic electrophoretic coating original paint as described in the first aspect.

[0057] Preferably, the mass ratio of the acrylic cathodic electrophoretic coating original paint to water is 1:(8-10), for example, 1:8.2, 1:8.4, 1:8.6, 1:8.8, 1:9, 1:9.2, 1:9.4, 1:9.6 or 1:9.8, etc.

[0058] In a fourth aspect, the present invention provides an electrophoretic coating, which is obtained by electrophoretic film formation and drying of the electrophoretic coating material as described in the third aspect.

[0059] Preferably, the drying comprises gradient drying.

[0060] Preferably, the gradient drying includes a first drying, a second drying and a third drying performed sequentially.

[0061] Preferably, the temperature of the first drying is 80-100°C (for example, 82°C, 84°C, 86°C, 88°C, 90°C, 92°C, 94°C, 96°C or 98°C, etc.), and the time is 15-20 min (for example, 15.5 min, 16 min, 16.5 min, 17 min, 17.5 min, 18 min, 18.5 min, 19 min or 19.5 min, etc.).

[0062] Preferably, the temperature of the second drying is 100-130°C (for example, 105°C, 110°C, 115°C, 120°C or 125°C, etc.), and the time is 15-20 min (for example, 15.5 min, 16 min, 16.5 min, 17 min, 17.5 min, 18 min, 18.5 min, 19 min or 19.5 min, etc.).

[0063] Preferably, the temperature of the third drying is 130-160°C (for example, 135°C, 140°C, 145°C, 150°C or 155°C, etc.), and the time is 15-20 min (for example, 15.5 min, 16 min, 16.5 min, 17 min, 17.5 min, 18 min, 18.5 min, 19 min or 19.5 min, etc.).

[0064] Compared with the prior art, the present invention has the following beneficial effects:

[0065] In the present invention, the acrylic cathode electrophoretic coating original paint is prepared by compounding components such as modified epoxy resin prepolymer, tertiary amine-containing acrylate monomer, hydroxyl-containing acrylate monomer, styrene, isooctyl acrylate, surfactant, vinyl oxazoline, unsaturated carboxylic acid ammonium salt, solvent A, initiator and low-temperature curing agent. The electrophoretic coating containing the acrylic cathode electrophoretic coating original paint can be stored at room temperature for more than half a year, and can be used continuously for more than 15 days in a paint tank, and has good stability; the vinyl oxazoline, unsaturated carboxylic acid ammonium salt and low-temperature curing agent are matched, so that the electrophoretic coating formed by electrophoretic film formation and drying of the electrophoretic coating has a multiple cross-linking system, introduces more cross-linking points, increases the density of the electrophoretic coating, and makes it perform better in response to external physical and chemical erosion. The prepared electrophoretic coating has the characteristics of good sweat resistance, salt spray resistance and high hardness. DETAILED DESCRIPTION

[0066] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0067] Preparation Example 1

[0068] This preparation example provides a modified epoxy resin prepolymer, specifically a modified epoxy resin prepolymer A1, which is prepared by the following method:

[0069] An organic amine (octylamine) was put into a four-necked flask, nitrogen was passed through, and the temperature was raised to 75°C. Then, solvent B (ethylene glycol butyl ether) and epoxy resin (E128 epoxy resin, Sanmu Chemical) in a mass ratio of 1:3 were evenly mixed and dropped into the four-necked flask. The dropping time was 2.5 h. The mass ratio of the organic amine (octylamine) and epoxy resin (E128 epoxy resin, Sanmu Chemical) was 1:2.5. After the reaction was kept warm for 1.5 h, the temperature was cooled to room temperature to obtain the modified epoxy resin prepolymer A1.

[0070] Preparation Example 2

[0071] This preparation example provides a modified epoxy resin prepolymer, specifically a modified epoxy resin prepolymer A2, which is prepared by the following method:

[0072] An organic amine (octylamine) was put into a four-necked flask, nitrogen was passed through, and the temperature was raised to 78°C. Then, solvent B (isopropanol) and epoxy resin (E128 epoxy resin, Sanmu Chemical) in a mass ratio of 1:4 were evenly mixed and dropped into the four-necked flask. The dropping time was 2 h. The mass ratio of the organic amine (octylamine) and epoxy resin (E128 epoxy resin, Sanmu Chemical) was 1:3. After keeping the temperature for reaction for 2 h, the temperature was cooled to room temperature to obtain the modified epoxy resin prepolymer A2.

[0073] Preparation Example 3

[0074] This preparation example provides a modified epoxy resin prepolymer, specifically a modified epoxy resin prepolymer A3, which is prepared by the following method:

[0075] An organic amine (octylamine) was put into a four-necked flask, nitrogen was passed through, and the temperature was raised to 80°C. Then, solvent B (isopropanol) and epoxy resin (E128 epoxy resin, Sanmu Chemical) in a mass ratio of 1:5 were evenly mixed and dropped into the four-necked flask. The dropping time was 3 h. The mass ratio of the organic amine (octylamine) and epoxy resin (E128 epoxy resin, Sanmu Chemical) was 1:3.3. After the reaction was kept warm for 1 h, the temperature was cooled to room temperature to obtain the modified epoxy resin prepolymer A3.

[0076] Example 1

[0077] The present embodiment provides an acrylic cathode electrophoretic coating original paint and a preparation method thereof and an electrophoretic coating. The raw materials for preparing the acrylic cathode electrophoretic coating original paint include the following components in parts by weight: 5 parts of a modified epoxy resin prepolymer (modified epoxy resin prepolymer A1 provided in Preparation Example 1), 10 parts of an acrylate monomer containing a tertiary amine group (dimethylaminoethyl methacrylate), 20 parts of an acrylate monomer containing a hydroxyl group (hydroxypropyl methacrylate), 35 parts of styrene, 4 parts of isooctyl acrylate, and 0. 4 parts, vinyl oxazoline (2-vinyl-2-oxazoline) 2.5 parts, unsaturated carboxylic acid ammonium salt (ammonium acrylate) 2.5 parts, solvent A (ethylene glycol butyl ether) 20 parts, initiator (azobisisobutyronitrile) 1 part, low-temperature curing agent (isophorone diisocyanate and isophorone diamine unblocked at 90°C in a mass ratio of 1:0.75) 20 parts, neutralizer (acetic acid) 2.5 parts and leveling agent (Digo KL245) 0.75 parts, the above-mentioned surfactant is polypropylene glycol (200) diacrylate.

[0078] The preparation method of the above acrylic cathodic electrophoretic coating original paint comprises the following steps:

[0079] (1) mixing a tertiary amine-containing acrylic acid ester monomer, a hydroxyl-containing acrylic acid ester monomer, styrene, isooctyl acrylate, a surfactant, vinyl oxazoline, an unsaturated carboxylic acid ammonium salt and a portion of an initiator, wherein the weight of the portion of the initiator is 82% based on the total weight of the initiator being 100%, to obtain a monomer mixture;

[0080] (2) The modified epoxy resin prepolymer and solvent A are mixed, the temperature is raised to 112° C., the monomer mixture prepared in step (1) is added dropwise to carry out a first heat preservation reflux reaction, the addition time is 4 h, and then the remaining initiator is added to carry out a second heat preservation reflux reaction for 1.6 h. During the heat preservation reaction, the remaining initiator is added in 3 times, 0.06 parts by weight each time, and the addition time interval is 0.5 h. After the heat preservation reaction is completed, the temperature is lowered to 75° C., a low-temperature curing agent, a neutralizing agent and a leveling agent are added, and the mixture is stirred and mixed for 25 min to obtain the acrylic cathode electrophoretic coating original paint.

[0081] The electrophoretic coating is prepared by the following method: the acrylic cathode electrophoretic coating original paint and deionized water are mixed in a mass ratio of 1:9 to obtain the electrophoretic coating.

[0082] Example 2

[0083] The present embodiment provides an acrylic cathode electrophoretic coating original paint, a preparation method thereof, and an electrophoretic coating. The raw materials for preparing the acrylic cathode electrophoretic coating original paint include the following components in parts by weight: 6 parts of a modified epoxy resin prepolymer (modified epoxy resin prepolymer A2 provided in Preparation Example 2), 6 parts of an acrylate monomer containing a tertiary amine group (dimethylaminoethyl methacrylate), 30 parts of an acrylate monomer containing a hydroxyl group (hydroxypropyl acrylate), 30 parts of styrene, 1 part of isooctyl acrylate, and 0.3 parts of a surfactant. , vinyl oxazoline (2-vinyl-2-oxazoline) 2.77 parts, unsaturated carboxylic acid ammonium salt (ammonium acrylate) 2.23 parts, solvent A (ethylene glycol butyl ether) 10 parts, initiator (azobisisobutyronitrile) 0.8 parts, low-temperature curing agent (isophorone diisocyanate and isophorone diamine unblocked at 90°C in a mass ratio of 1:0.75) 30 parts, neutralizer (acetic acid) 2 parts and leveling agent (Digo KL245) 0.5 parts, the above-mentioned surfactant is polypropylene glycol (200) diacrylate.

[0084] The preparation method of the above acrylic cathodic electrophoretic coating original paint comprises the following steps:

[0085] (1) mixing a tertiary amine-containing acrylic acid ester monomer, a hydroxyl-containing acrylic acid ester monomer, styrene, isooctyl acrylate, a surfactant, vinyl oxazoline, an unsaturated carboxylic acid ammonium salt and a portion of an initiator, wherein the weight of the portion of the initiator is 74% based on the total weight of the initiator being 100%, to obtain a monomer mixture;

[0086] (2) The modified epoxy resin prepolymer and solvent A are mixed, the temperature is raised to 115° C., the monomer mixture prepared in step (1) is added dropwise to carry out a first heat preservation reflux reaction, the addition time is 3 h, and then the remaining initiator is added to carry out a second heat preservation reflux reaction for 2 h. The remaining initiator is added in 3 times, 0.07 parts by weight each time, and the addition time interval is 0.6 h. After the heat preservation reaction is completed, the temperature is lowered to 80° C., a low-temperature curing agent, a neutralizing agent and a leveling agent are added, and the mixture is stirred and mixed for 20 min to obtain the acrylic cathode electrophoretic coating original paint.

[0087] The electrophoretic coating is prepared by the following method: the acrylic cathode electrophoretic coating original paint and deionized water are mixed in a mass ratio of 1:10 to obtain the electrophoretic coating.

[0088] Example 3

[0089] The present embodiment provides an acrylic cathode electrophoretic coating original paint and a preparation method thereof and an electrophoretic coating. The raw materials for preparing the acrylic cathode electrophoretic coating original paint include the following components in parts by weight: 4 parts of a modified epoxy resin prepolymer (modified epoxy resin prepolymer A3 provided in Preparation Example 3), 15 parts of an acrylate monomer containing a tertiary amino group (dimethylaminoethyl methacrylate), 20 parts of an acrylate monomer containing a hydroxyl group (hydroxyethyl acrylate), 40 parts of styrene, 6 parts of isooctyl acrylate, and 0. 5 parts, vinyl oxazoline (2-vinyl-2-oxazoline) 2.5 parts, unsaturated carboxylic acid ammonium salt (ammonium acrylate) 2.5 parts, solvent A (ethylene glycol butyl ether) 30 parts, initiator (azobisisobutyronitrile) 1.5 parts, low temperature curing agent (isophorone diisocyanate and isophorone diamine unblocked at 90°C with a mass ratio of 1:0.75) 10 parts, neutralizer (acetic acid) 3 parts and leveling agent (Digo KL245) 0.8 parts, the above-mentioned surfactant is polypropylene glycol (200) diacrylate.

[0090] The preparation method of the above acrylic cathodic electrophoretic coating original paint comprises the following steps:

[0091] (1) mixing a tertiary amine-containing acrylic acid ester monomer, a hydroxyl-containing acrylic acid ester monomer, styrene, isooctyl acrylate, a surfactant, vinyl oxazoline, an unsaturated carboxylic acid ammonium salt and a portion of an initiator, wherein the weight of the portion of the initiator is 80% based on the total weight of the initiator being 100%, to obtain a monomer mixture;

[0092] (2) The modified epoxy resin prepolymer and solvent A are mixed, the temperature is raised to 110° C., the monomer mixture prepared in step (1) is added dropwise to carry out a first heat preservation reflux reaction, the addition time is 5 h, and then the remaining initiator is added to carry out a second heat preservation reflux reaction for 1.3 h. During the heat preservation reaction, the remaining initiator is added three times, 0.1 parts by weight each time, and the addition time interval is 0.4 h. After the heat preservation reaction is completed, the temperature is lowered to 70° C., a low-temperature curing agent, a neutralizing agent and a leveling agent are added, and the mixture is stirred and mixed for 30 min to obtain the acrylic cathode electrophoretic coating original paint.

[0093] The electrophoretic coating is prepared by the following method: the acrylic cathode electrophoretic coating original paint and deionized water are mixed in a mass ratio of 1:8 to obtain the electrophoretic coating.

[0094] Example 4

[0095] This embodiment provides an acrylic cathode electrophoretic coating original paint, a preparation method thereof, and an electrophoretic coating. The only difference between this embodiment and Embodiment 1 is that the weight proportions of vinyl oxazoline (2-vinyl-2-oxazoline) and unsaturated carboxylic acid ammonium salt (ammonium acrylate) are both adjusted to 5 parts, and other conditions are the same as those in Embodiment 1.

[0096] Example 5

[0097] This embodiment provides an acrylic cathode electrophoretic coating original paint, a preparation method thereof, and an electrophoretic coating. The only difference between this embodiment and Embodiment 1 is that the weight proportions of vinyl oxazoline (2-vinyl-2-oxazoline) and unsaturated carboxylic acid ammonium salt (ammonium acrylate) are both adjusted to 1.5 parts, and other conditions are the same as those in Embodiment 1.

[0098] Example 6

[0099] This embodiment provides an acrylic cathode electrophoretic coating original paint, a preparation method thereof, and an electrophoretic coating. The difference between this embodiment and Example 1 is that the weight proportion of the modified epoxy resin prepolymer (modified epoxy resin prepolymer A1 provided in Preparation Example 1) is adjusted to 3 parts, and other conditions are the same as those in Example 1.

[0100] Example 7

[0101] This embodiment provides an acrylic cathode electrophoretic coating original paint, a preparation method thereof, and an electrophoretic coating. The difference between this embodiment and embodiment 1 is that the weight portion of the surfactant is adjusted to 0.2 parts, and other conditions are the same as those in embodiment 1.

[0102] Example 8

[0103] This embodiment provides an acrylic cathode electrophoretic coating original paint, a preparation method thereof, and an electrophoretic coating. The difference between this embodiment and embodiment 1 is that the weight portion of the surfactant is adjusted to 0.6 parts, and other conditions are the same as those in embodiment 1.

[0104] Comparative Example 1

[0105] This comparative example provides an acrylic cathode electrophoretic coating original paint, a preparation method thereof, and an electrophoretic coating, which differs from Example 1 only in that vinyl oxazoline (2-vinyl-2-oxazoline) and unsaturated carboxylic acid ammonium salt (ammonium acrylate) are not added, and other conditions are the same as those in Example 1.

[0106] Comparative Example 2

[0107] This comparative example provides an acrylic cathode electrophoretic coating original paint, a preparation method thereof, and an electrophoretic coating, which is different from Example 1 only in that, if the modified epoxy resin prepolymer is not added, other conditions are the same as those of Example 1.

[0108] Comparative Example 3

[0109] This comparative example provides an acrylic cathode electrophoretic coating original paint, a preparation method thereof, and an electrophoretic coating, which differs from Example 1 only in that the weight portion of the modified epoxy resin prepolymer (modified epoxy resin prepolymer A1 provided in Preparation Example 1) is adjusted to 2 parts, and other conditions are the same as those in Example 1.

[0110] Comparative Example 4

[0111] This comparative example provides an acrylic cathode electrophoretic coating original paint, a preparation method thereof, and an electrophoretic coating, which differs from Example 1 only in that the weight fraction of the modified epoxy resin prepolymer (modified epoxy resin prepolymer A1 provided in Preparation Example 1) is adjusted to 8 parts, and other conditions are the same as those in Example 1.

[0112] The electrophoretic coating materials provided in the above-mentioned Examples 1 to 8 and Comparative Examples 1 to 4 were prepared into electrophoretic coatings, and the following tests were performed.

[0113] Preparation of electrophoretic coating: put the electrophoretic coating into the paint tank, connect the electrode plate with the anode of the electrophoretic instrument, and connect the workpiece with the cathode of the electrophoretic instrument. The workpiece is a 304 stainless steel plate or a 304 stainless steel eyeglass frame. The length of the 304 stainless steel plate is 40mm and the width is 30mm. The electrophoresis voltage is 65V and the electrophoresis time is 30 seconds. After the electrophoresis, rinse the floating paint on the surface of the workpiece with deionized water, dry the surface moisture at 50℃, and put it in the oven. The oven temperature is stepped, dried at 80℃ for 10min, dried at 130℃ for 10min, and dried at 160℃ for 10min. The thickness of the prepared electrophoretic coating is controlled within the range of 15-20 μm.

[0114] Artificial sweat resistance time: The test is based on ISO12870, and artificial sweat is prepared with sodium chloride (analytical grade), lactic acid and pure water (the mass percentage of sodium chloride in artificial sweat is 10%, and the mass percentage of lactic acid is 5%). Pour the artificial sweat into the container, and then place the 304 stainless steel eyeglass frame containing the electrophoretic coating on the tray in the container in a naturally open state (the 304 stainless steel eyeglass frame does not come into contact with the artificial sweat), and seal the container; heat it to 55°C, take it out after 8 hours, observe the inner and outer surface conditions of the 304 stainless steel eyeglass frame containing the electrophoretic coating and record it. If there is no corrosion, discoloration, plating loss and other adverse phenomena, put it back into the container, take it out again after 16 hours, and observe whether there is corrosion, discoloration, plating loss and other adverse phenomena on the inner and outer surfaces of the 304 stainless steel eyeglass frame containing the electrophoretic coating. If there is no corrosion, discoloration, plating loss and other adverse phenomena, continue to put it back into the container, repeat the steps of placing it in the container for 12 hours and taking it out for observation, until corrosion, discoloration or plating loss and other adverse phenomena appear, and record the result as artificial sweat resistance time ≥ the maximum time measured without the above adverse phenomena.

[0115] Hardness: Pencil hardness method, use a set of Zhonghua brand high-grade drawing pencils, the pencil numbers are 6H, 5H, 4H, 3H, 2H, H, B, 2B, fix the 304 stainless steel plate with electrophoretic coating on a horizontal plane, hold the sharpened pencil so that it is at a 45° angle to the electrophoretic coating, push it forward at a speed of 1mm / s, and use enough force to break the edge of the pencil or plow through the coating; start with the hardest pencil until you find a pencil that cannot plow through the coating. The hardness of this pencil is the hardness of the coating.

[0116] Conductivity: Use a conductivity meter to test, and the displayed value is the conductivity.

[0117] Salt spray resistance: tested according to ASTM B117-73 (1979) standard.

[0118] Scratch resistance: tested according to ASTMD 5178-1998 standard.

[0119] The electrophoretic coatings provided in the above-mentioned Examples 1 to 8 and Comparative Examples 1 to 4 were subjected to a stability test: the prepared electrophoretic coatings were placed in a 50° C. oven for 30 days to observe whether the electrophoretic coatings had precipitation, agglomeration, or stratification. If there was no precipitation, agglomeration, or stratification, the electrophoretic coatings were made to test whether the artificial sweat resistance, hardness, salt spray resistance, and scratch resistance decreased.

[0120] The test results are shown in Table 1 below.

[0121] Table 1

[0122]

[0123] It can be seen from the contents of Table 1 that the electrophoretic coatings made of the electrophoretic coatings provided in Examples 1-8 have high gloss, artificial sweat resistance time ≥48h, hardness of 3H-6H, salt spray resistance ≥800h, scratch resistance ≥1000 g, and conductivity of 400~600μS / cm.

[0124] Compared with Example 1, if the weight ratio of vinyl oxazoline and unsaturated carboxylic acid ammonium salt is too high (Example 4), the artificial sweat resistance time of the obtained electrophoretic coating is slightly reduced. The reason is that the excessively high cross-linking density leads to a high film shrinkage rate, the coating becomes hard and brittle, and the adhesion is reduced; if the mass ratio of vinyl oxazoline and unsaturated carboxylic acid ammonium salt is too low (Example 5), the self-cross-linking density is reduced, and the coating's ability to resist sweat erosion is reduced.

[0125] Compared with Example 1, if the weight fraction of the modified epoxy resin prepolymer is lower (Example 6), the artificial sweat resistance time, hardness and scratch resistance of the prepared electrophoretic coating are slightly reduced.

[0126] Compared with Example 1, if the weight fraction of the surfactant is too low (Example 7), the stability of the prepared electrophoretic coating is reduced; if the weight fraction of the surfactant is too high (Example 8), the artificial sweat resistance time of the prepared electrophoretic coating is slightly reduced.

[0127] Compared with Example 1, if the cross-linking monomer is not added (Comparative Example 1), the sweat resistance and salt spray resistance of the prepared electrophoretic coating are greatly reduced. It can be seen that the present invention prepares acrylic cathode electrophoretic coating original paint and electrophoretic coating with better performance by adding vinyl oxazoline and unsaturated carboxylic acid ammonium salt.

[0128] Compared with Example 1, if the modified epoxy resin prepolymer is not added (Comparative Example 2), the performance of the prepared electrophoretic coating is greatly reduced, especially the hardness is significantly reduced. The reason is that the epoxy resin itself is a rigid resin, and although the acrylic resin has good flexibility, it is insufficient in rigidity. If the modified epoxy resin prepolymer is not added, the hardness of the prepared electrophoretic coating is insufficient and the scratch resistance is reduced. In addition, not adding the modified epoxy resin prepolymer will also lead to a lack of polar groups in the resin mixture, thereby failing to provide sufficient adhesion, and due to the reduction in cross-linking density, the prepared electrophoretic coating is more susceptible to sweat and salt spray corrosion. It can be seen that the present invention adds modified epoxy resin prepolymers and compounds with other components to prepare acrylic cathode electrophoretic coatings. The original paint and electrophoretic coating have better performance.

[0129] Compared with Example 1, if the weight fraction of the modified epoxy resin prepolymer is too low (Comparative Example 3), the artificial sweat resistance and salt spray resistance of the prepared electrophoretic coating are reduced; if the weight fraction of the modified epoxy resin prepolymer is too high (Comparative Example 4), the hardness and scratch resistance of the prepared electrophoretic coating are improved, but the artificial sweat resistance is significantly reduced. It can be seen that the acrylic cathode electrophoretic coating original paint and electrophoretic coating prepared by controlling the weight fraction of the modified epoxy resin prepolymer within a specific range have better performance.

[0130] The applicant declares that the present invention uses the above-mentioned embodiments to illustrate an acrylic cathode electrophoretic coating original paint and its preparation method and application, but the present invention is not limited to the above-mentioned embodiments, that is, it does not mean that the present invention must rely on the above-mentioned embodiments to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. An acrylic cathodic electrophoretic coating original paint, characterized in that: The raw materials for preparing the acrylic cathode electrophoretic coating include the following components in parts by weight: 3-7 parts of modified epoxy resin prepolymer, 5-20 parts of tertiary amine-containing acrylate monomer, 8-30 parts of hydroxyl-containing acrylate monomer, 30-40 parts of styrene, 1-6 parts of isooctyl acrylate, 0.3-0.6 parts of surfactant, 1-10 parts of crosslinking monomer, 10-30 parts of solvent A, 0.5-1.5 parts of initiator and 10-30 parts of low-temperature curing agent; The modified epoxy resin prepolymer is prepared by the following method: an organic amine, an epoxy resin and a solvent B are mixed and reacted to obtain the modified epoxy resin prepolymer; The cross-linking monomers include vinyl oxazoline and unsaturated carboxylic acid ammonium salt; The organic amine includes octylamine; The mass ratio of the organic amine to the epoxy resin is 1:(2.5-3.3); The mass ratio of the solvent B to the epoxy resin is 1:(3-5); The raw materials for preparing the acrylic cathodic electrophoretic coating include 0.5 to 5 parts by weight of vinyl oxazoline and 0.5 to 5 parts by weight of unsaturated carboxylic acid ammonium salt; The mass ratio of the vinyl oxazoline to the unsaturated carboxylic acid ammonium salt is 1:(0.8-1.2); The solvent A includes any one of n-butanol, isopropanol, ethylene glycol butyl ether, propylene glycol methyl ether or propylene glycol butyl ether, or a combination of at least two thereof.

2. The original acrylic cathodic electrophoretic paint according to claim 1, characterized in that: The solvent B comprises any one of n-butanol, isopropanol, ethylene glycol butyl ether, propylene glycol methyl ether or propylene glycol butyl ether, or a combination of at least two thereof; The mixing of the organic amine, epoxy resin and solvent B specifically includes dropping the mixture of epoxy resin and solvent B into the organic amine and mixing; The time of the dropwise addition is 2 to 3 h; The reaction temperature is 75-80°C and the reaction time is 1-2 h.

3. The original acrylic cathodic electrophoretic paint according to claim 1, characterized in that: The tertiary amine-containing acrylate monomer includes dimethylaminoethyl methacrylate; The hydroxyl-containing acrylic acid ester monomer includes any one of hydroxypropyl methacrylate, hydroxypropyl acrylate, hydroxyethyl methacrylate or hydroxyethyl acrylate, or a combination of at least two thereof.

4. The original acrylic cathodic electrophoretic paint according to claim 1, characterized in that: The surfactant includes polypropylene glycol diacrylate; The vinyl oxazoline includes 2-vinyl-2-oxazoline; The unsaturated carboxylic acid ammonium salt includes ammonium acrylate; The initiator includes azobisisobutyronitrile.

5. The original acrylic cathodic electrophoretic paint according to claim 1, characterized in that: The low temperature curing agent includes a blocked isocyanate curing agent and an amine curing agent; The mass ratio of the blocked isocyanate curing agent to the amine curing agent is 1:(0.5~1); The blocked isocyanate curing agent includes isophorone diisocyanate which is unblocked at 80-90°C; The amine curing agent includes isophoronediamine.

6. The original acrylic cathodic electrophoretic paint according to claim 1, characterized in that: The acrylic cathodic electrophoretic coating original paint also includes a neutralizer and / or a leveling agent; The weight proportion of the neutralizing agent in the raw material for preparing the acrylic cathodic electrophoretic coating is 1 to 5 parts; The neutralizing agent includes a weak acid; The weight proportion of the leveling agent in the raw materials for preparing the acrylic cathode electrophoretic coating is 0.5 to 0.8 parts.

7. A method for preparing the original acrylic cathodic electrophoretic paint according to any one of claims 1 to 6, characterized in that: The preparation method comprises the following steps: (1) mixing a tertiary amine-containing acrylic ester monomer, a hydroxyl-containing acrylic ester monomer, styrene, isooctyl acrylate, a surfactant, vinyl oxazoline, an unsaturated carboxylic acid ammonium salt and a portion of an initiator to obtain a monomer mixture; (2) mixing the monomer mixture obtained in step (1), the modified epoxy resin prepolymer, the solvent A, and the remaining initiator for reflux reaction, adding a low-temperature curing agent and mixing to obtain the acrylic cathode electrophoretic coating original paint; Based on the total weight of the initiator being 100%, the weight of the initiator in the part is 70% to 85%.

8. The preparation method according to claim 7, characterized in that: Step (2) specifically comprises the following steps: mixing the modified epoxy resin prepolymer and solvent A, heating to 110-115° C., dripping the monomer mixture obtained in step (1) to carry out a first heat preservation reflux reaction, the dripping time is 3-5 hours, then adding the remaining initiator to carry out a second heat preservation reflux reaction for 1-2 hours, cooling to 70-80° C., adding a low-temperature curing agent, a neutralizing agent and a leveling agent, stirring and mixing for 20-30 minutes, and obtaining the acrylic cathode electrophoretic coating original paint.

9. An electrophoretic coating, characterized in that: The electrophoretic coating comprises water and the acrylic cathodic electrophoretic coating original paint as claimed in any one of claims 1 to 6.

10. An electrophoretic coating, characterized in that: The electrophoretic coating is obtained by electrophoretic film formation and drying of the electrophoretic coating material as claimed in claim 9.

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