Tin-free modified epoxy cathode electrophoretic paint and preparation method thereof

Abstract

The invention provides a tin-free modified epoxy cathode electrophoretic paint and a preparation method thereof, and belongs to the technical field of electrophoretic paint preparation. The anti-shrinkage coating comprises the following components in percentage by weight: 30%-35% of modified epoxy resin, 4%-6% of an alcohol ether solvent, 1%-2% of N-methylethanolamine, 0.5%-1% of ketimine resin, 2%-3% of D2000, 12%-15% of an RY-627 cross-linking agent, 0.5%-1% of a defoaming agent, 0.1%-0.2% of a wetting agent, 0.2%-0.4% of an anti-shrinkage auxiliary agent, 0.5%-1% of BiCat-1050, 1%-2% of acetic acid and 50%-55% of pure water. According to the invention, the problem of tin-free catalysis can be solved, so that the ketimine system electrophoretic paint can thoroughly realize tin-free treatment, the high-performance product can be greatly popularized in the market, the product is more environment-friendly, and the core competitiveness of the product is greatly improved.

Description

Technical Field

[0001] The invention relates to the technical field of electrophoretic paint preparation, and in particular to a Wuxi modified epoxy cathode electrophoretic paint and a preparation method thereof. Background Art

[0002] At present, cathodic electrophoretic paints all use organic tin as a catalyst in the paint film curing stage, especially electrophoretic paints synthesized from ketimine resins. At present, there are basically no ketimine electrophoretic paints in Wuxi. That is because if other catalysts are added to the system, such as metal bismuth catalysts, the paint film will appear flowery, local dryness is inconsistent and other paint film defects. This phenomenon is more obvious when organic bismuth encounters phosphate (pretreatment protective layer). Not only does the photocatalytic performance of the paint film fail, but the surface of the paint film will become very ugly, and various performances will be significantly reduced. Therefore, the present application provides a Wuxi modified epoxy cathodic electrophoretic paint and a preparation method to meet the needs. Summary of the invention

[0003] The technical problem to be solved by the present invention is to provide a tin-free modified epoxy cathode electrophoretic paint and a preparation method thereof to solve the existing problems.

[0004] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0005] A Wuxi modified epoxy cathode electrophoretic paint comprises the following components in percentage: modified epoxy resin: 30%-35%, alcohol ether solvent: 4%-6%, N-methylethanolamine: 1%-2%, ketimine resin: 0.5%-1%, D2000: 2%-3%, RY-627 crosslinking agent: 12%-15%, defoaming agent: 0.5%-1%, wetting agent: 0.1%-0.2%, anti-shrinkage crater additive: 0.2%-0.4%, BiCat-1050: 0.5%-1%, acetic acid: 1%-2%, and pure water: 50%-55%.

[0006] In some examples, the modified epoxy resin is synthesized by high temperature reaction of 128 epoxy resin, bisphenol A, a modifier and a catalyst.

[0007] A method for preparing a tin-free modified epoxy cathode electrophoretic paint comprises the following steps:

[0008] S1. Synthesize improved epoxy resin by reacting 128 epoxy resin, bisphenol A, modifier and catalyst at high temperature, and control the epoxy resin temperature to 840±20;

[0009] S2. Add alcohol ether solvent into the improved epoxy resin at 150°C and stir well;

[0010] S3, when the temperature reaches 100°C, add N-methylethanolamine, ketimine resin and D2000 to the resin for amination reaction, control the temperature between 105°C and 115°C, react for 2 hours, and obtain a mixture A;

[0011] S4, add RY-627 crosslinking agent to mixture A, lower the temperature to 80°C, continue to add defoamer, wetting agent, anti-shrinkage aid, catalyst, and stir for 0.5 hours;

[0012] S5, adding acetic acid for neutralization, acidifying the resin, and then slowly adding pure water to prepare a water-soluble cathode electrophoretic paint emulsion;

[0013] S6. Mix the cathode electrophoretic paint emulsion and SJ-627 color paste in a ratio of 4:1, and add an appropriate amount of pure water to prepare a 15% concentration of electrophoretic working solution.

[0014] Compared with the prior art, the present invention has at least the following beneficial effects:

[0015] In the above scheme, by adding BiCat-1050 as a catalyst, the problem of tin-free catalysis is solved, so that the ketimine system electrophoretic paint can be completely tin-free, so that this high-performance product can be widely promoted in the market, the product is more green and environmentally friendly, and the core competitiveness of the product is greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings, which are incorporated herein and constitute a part of the specification, illustrate embodiments of the present disclosure and, together with the description, further serve to explain the principles of the present disclosure and to enable those skilled in the relevant art to make and use the present disclosure.

[0017] Figure 1 The present invention is a flow chart of a method for preparing a tin-modified epoxy cathode electrophoretic paint. DETAILED DESCRIPTION

[0018] The following is a detailed description of a tin-free modified epoxy cathode electrophoretic paint and a preparation method provided by the present invention in conjunction with the accompanying drawings and specific embodiments. At the same time, it is explained here that in order to make the embodiments more detailed, the following embodiments are listed as the best and preferred embodiments, and other alternatives can also be used by technicians in some known technical fields; and the accompanying drawings are only for more specific description of the embodiments, and are not intended to specifically limit the present invention.

[0019] It should be noted that the references to "one embodiment", "embodiment", "exemplary embodiment", "some embodiments" and the like in the specification indicate that the embodiments described may include specific features, structures or characteristics, but not every embodiment may include the specific features, structures or characteristics. In addition, when a specific feature, structure or characteristic is described in conjunction with an embodiment, it should be within the knowledge of a person skilled in the art to implement such feature, structure or characteristic in conjunction with other embodiments (whether or not explicitly described).

[0020] In general, a term can be understood, at least in part, from its use in context. For example, depending, at least in part, on the context, the term "one or more" as used herein can be used to describe any feature, structure, or characteristic in the singular sense, or can be used to describe a combination of features, structures, or characteristics in the plural sense. Additionally, the term "based on" can be understood as not necessarily intended to convey an exclusive set of factors, but can instead, depending, at least in part, on the context, allow for the presence of other factors that are not necessarily explicitly described.

[0021] It will be understood that the meaning of “on,” “over,” and “above” in this disclosure should be interpreted in the broadest manner, so that “on” not only means “directly on” something, but also includes the meaning of being “on” something with intervening features or layers therebetween, and “on” or “over” not only means “on” or “above” something, but also includes the meaning of being “on” or “above” something with no intervening features or layers therebetween.

[0022] Additionally, spatially relative terms such as "under," "beneath," "lower," "above," "upper," and the like may be used herein for descriptive convenience to describe the relationship of one element or feature to another element or features, as shown in the accompanying drawings. Spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the accompanying drawings. The device may be oriented in other ways, and the spatially relative descriptors used herein may be similarly interpreted accordingly.

[0023] Example 1

[0024] An embodiment of the present invention provides a Wuxi modified epoxy cathode electrophoretic paint, which includes the following components in percentage: modified epoxy resin: 30%-35%, alcohol ether solvent: 4%-6%, N-methylethanolamine: 1%-2%, ketimine resin: 0.5%-1%, D2000: 2%-3%, RY-627 cross-linking agent: 12%-15%, defoaming agent: 0.5%-1%, wetting agent: 0.1%-0.2%, anti-shrinkage crater additive: 0.2%-0.4%, BiCat-1050: 0.5%-1%, acetic acid: 1%-2%, and pure water: 50%-55%.

[0025] It should be further explained in this embodiment that the modified epoxy resin is synthesized by high temperature reaction of 128 epoxy resin, bisphenol A, a modifier and a catalyst.

[0026] Example 2

[0027] like Figure 1 As shown, a method for preparing a tin-free modified epoxy cathode electrophoretic paint comprises the following steps:

[0028] S1. Synthesize improved epoxy resin by reacting 128 epoxy resin, bisphenol A, modifier and catalyst at high temperature, and control the epoxy resin temperature to 840±20;

[0029] S2. Add alcohol ether solvent into the improved epoxy resin at 150°C and stir well;

[0030] S3, when the temperature reaches 100°C, add N-methylethanolamine, ketimine resin and D2000 to the resin for amination reaction, control the temperature between 105°C and 115°C, react for 2 hours, and obtain a mixture A;

[0031] S4, add RY-627 crosslinking agent to mixture A, lower the temperature to 80°C, continue to add defoamer, wetting agent, anti-shrinkage aid, catalyst, and stir for 0.5 hours;

[0032] S5, adding acetic acid for neutralization, acidifying the resin, and then slowly adding pure water to prepare a water-soluble cathode electrophoretic paint emulsion;

[0033] S6. Mix the cathode electrophoretic paint emulsion and SJ-627 color paste in a ratio of 4:1, and add an appropriate amount of pure water to prepare a 15% concentration of electrophoretic working solution.

[0034] Select a variety of organic bismuth catalysts for screening experiments, and use phosphating plate electrophoresis to compare the blooming of the paint film on the phosphating plate surface, as well as the difference in gloss between the phosphating plate and the non-phosphating plate;

[0035] T25, LK-2, and BiCat-1050 were selected for screening tests, and a catalyst with less repulsion to phosphate ions was selected;

[0036] Add 0.5% (since the effective concentration of BiCat-1050 is only 50%, the added amount is 1%) catalyst to the emulsion, and then mix the three emulsions with SJ-627 color paste in a 4:1 ratio, and add appropriate amount of pure water to adjust the solid content of the bath liquid to 15%. After the bath liquid is matured for 24 hours, the board making begins. The electrophoresis conditions are: 140V / 20min, and the paint film thickness is controlled at about 20 microns. The sample material is: standard phosphating board, and the baking conditions are: 175℃ / 20min.

[0037]

[0038] Table 1

[0039] From Table 1, we can see that BiCat-1050 has the best effect in terms of curing degree and compatibility for sample No. 3, so we choose BiCat-1050 as our final catalyst;

[0040] The actual electrophoretic platemaking evaluation of the electrophoretic paint prepared by the above formula and method is as follows:

[0041] Serial number project Bath liquid control index Detection Methods Actual test results 1 Solid content (14±4)％ GB / T1725 15％ 2 pH 5.8±0.2 GB / T9724 5.7 3 Conductivity (1400±400)μs / cm HG / T3334 1260μs / cm 4 Ash (12±2)％ HG / T3952-5.4.2.4 11％ 5 Solvent content (2±0.5)％ HG / T3952 Appendix B 1.63％ 6 Ripening time ≥24 hours —— 24 hours 7 Application temperature (30±2)℃ thermometer 30℃ 8 Electrophoresis time (2±1)min —— 1min 9 Construction voltage (140±60)V Rectifier 120V 10 Curing conditions 175℃ / 20min GB / T1728 175℃ / 20min

[0042] The technical solution provided by the present invention can solve the problem of tin-free catalysis, so that the ketimine system electrophoretic paint can be completely tin-free, so that this high-performance product can be widely promoted on the market, the product is more green and environmentally friendly, and the core competitiveness of the product is greatly improved.

[0043] The present invention covers any substitution, modification, equivalent method and scheme made on the essence and scope of the present invention. In order to make the public have a thorough understanding of the present invention, specific details are described in detail in the following preferred embodiments of the present invention, but those skilled in the art can fully understand the present invention without the description of these details. In addition, in order to avoid unnecessary confusion about the essence of the present invention, well-known methods, processes, procedures, components and circuits are not described in detail.

[0044] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A tin-free modified epoxy cathodic electrophoretic paint, characterized in that: The following components are included in percentage: modified epoxy resin: 30% - 35%, alcohol ether solvent: 4% - 6%, N-methylethanolamine: 1% - 2%, ketimine resin: 0.5% - 1%, D2000: 2% - 3%, RY-627 cross-linking agent: 12% - 15%, defoaming agent: 0.5% - 1%, wetting agent: 0.1% - 0.2%, anti-shrinkage crater additive: 0.2% - 0.4%, BiCat-1050: 0.5% - 1%, acetic acid: 1% - 2%, pure water: 50% - 55%.

2. A tin-free modified epoxy cathodic electrophoretic paint according to claim 1, characterized in that: The modified epoxy resin is synthesized by high-temperature reaction of 128 epoxy resin, bisphenol A, a modifier and a catalyst.

3. A method for preparing a Wuxi modified epoxy cathode electrophoretic paint, applied to a Wuxi modified epoxy cathode electrophoretic paint as claimed in any one of claims 1 to 2, characterized in that: The following steps are involved: S1. Synthesize improved epoxy resin by reacting 128 epoxy resin, bisphenol A, modifier and catalyst at high temperature, and control the epoxy resin temperature to 840±20; S2. Add alcohol ether solvent into the improved epoxy resin at 150°C and stir well; S3, when the temperature reaches 100°C, add N-methylethanolamine, ketimine resin and D2000 to the resin for amination reaction, control the temperature between 105°C and 115°C, react for 2 hours, and obtain a mixture A; S4, add RY-627 crosslinking agent to mixture A, lower the temperature to 80°C, continue to add defoamer, wetting agent, anti-shrinkage aid, catalyst, and stir for 0.5 hours; S5, adding acetic acid for neutralization, acidifying the resin, and then slowly adding pure water to prepare a water-soluble cathode electrophoretic paint emulsion; S6. Mix the cathode electrophoretic paint emulsion and SJ-627 color paste in a ratio of 4:1, and add an appropriate amount of pure water to prepare a 15% concentration of electrophoretic working solution.

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