Primer-topcoat cathode electrophoretic coating meeting long-acting weather resistance and preparation method thereof

Abstract

The invention discloses a preparation method of a primer-topcoat cathode electrophoretic coating meeting long-acting weather resistance. The preparation method comprises the following steps: S1, preparing acrylic acid modified epoxy matrix resin; s2, preparing a blocked isocyanate cross-linking agent; and S3, mixing the acrylic acid modified epoxy matrix resin in the step S1 with the blocked isocyanate crosslinking agent in the step S2 to prepare the emulsion. According to the primer-topcoat cathode electrophoretic coating meeting the long-acting weather resistance and the preparation method thereof, a polymerizable light stabilizer with double bonds and a conventional acrylate monomer are copolymerized to epoxy resin, and the problem of poor stability of an epoxy and acrylic resin cold splicing coating is solved through a grafting method; meanwhile, the light stabilizer is grafted on the epoxy resin, so that migration is avoided, and the long-acting weather resistance can be met.

Description

Technical Field

[0001] The present invention relates to the technical field of water-based coatings, and in particular to a bottom-and-top integrated cathode electrophoretic coating that meets the requirements of long-term weather resistance and a preparation method thereof. Background Art

[0002] As a special coating that meets both salt spray resistance and weather resistance, the bottom-to-top integrated cathodic electrophoretic coating is widely used in electrophoretic coating fields such as automobile chassis, parts, and tricycles, motorcycles, and commercial vehicle frames that have weather resistance requirements.

[0003] The design principle of the current bottom-to-top cathode electrophoretic coatings on the market primarily relies on the different surface tensions of epoxy and acrylic resins. During the curing process of the electrophoretic paint film, the epoxy and acrylic resins self-separate, with the acrylic resin floating to provide effective weather resistance, while the epoxy resin sinks to provide effective salt spray resistance. Some coating manufacturers use a cold blending method of epoxy and acrylic emulsions, which results in poor long-term stability and unstable performance. While these products also utilize external light stabilizers to enhance weatherability, these products experience a sharp decline in weatherability after being placed outdoors for a period of time due to light stabilizer migration, resulting in gloss loss and chalking, making them unable to meet long-term weathering requirements. Summary of the Invention

[0004] In response to the above problems, the present invention provides a bottom-to-top integrated cathode electrophoretic coating that meets long-term weather resistance and a preparation method thereof. A double-bond polymerizable light stabilizer and a conventional acrylate monomer are copolymerized on an epoxy resin, and a grafting method is used to solve the problem of poor stability of epoxy and acrylic resin cold-blended coatings. At the same time, since the light stabilizer is grafted on the epoxy resin, it will not migrate, and long-term weather resistance can be met.

[0005] In one aspect, the present invention provides a method for preparing a bottom-to-top cathode electrophoretic coating that meets long-term weather resistance, comprising the following steps:

[0006] S1, preparing acrylic acid modified epoxy main resin;

[0007] S2, preparing a blocked isocyanate cross-linking agent;

[0008] S3. Mixing the acrylic modified epoxy main resin in step S1 with the blocked isocyanate cross-linking agent in step S2 to prepare an emulsion.

[0009] In certain embodiments, the acrylic modified epoxy main resin in step S1 includes the following components in parts by weight:

[0010]

[0011] In certain embodiments, the epoxy resin in step S1 has an epoxy equivalent of 184-1200, preferably a bisphenol A epoxy resin with an epoxy equivalent of 300-800, and particularly preferably a bisphenol A epoxy resin with an epoxy equivalent of 450-560; the organic solvent in step S1 is one of xylene, methyl isobutyl ketone, propylene glycol methyl ether, propylene glycol butyl ether, and ethylene glycol butyl ether, and preferably propylene glycol methyl ether; the initiator in step S1 is a peroxide initiator, and preferably BPO; the active hydrogen-containing amine compound in step S1 is a monovalent secondary amine, and preferably one of ketimine, alcoholamine, and alkylamine, and particularly preferably methylethanolamine.

[0012] In certain embodiments, the polymerizable light stabilizer is a double-bond polymerizable light stabilizer, and can be a hindered amine, a benzotriazole, or other polymerizable light stabilizer with light stabilization properties. Hindered amines and benzotriazoles can be used separately or in combination. Preferred hindered amines are ADK's LA-82 and LA-87, with LA-82 being particularly preferred. Preferred benzotriazoles are CHIGUARD 323.

[0013] In certain embodiments, the preparation method of the acrylic acid-modified epoxy main resin in step S1 is:

[0014] Mixing the formulated amounts of initiator, methyl methacrylate, hydroxyethyl methacrylate, butyl acrylate, glycidyl methacrylate, isobornyl methacrylate, and a polymerizable light stabilizer to obtain a mixed solution A;

[0015] Add the formulated amount of epoxy resin and organic solvent into a four-necked flask and heat it to 115°C;

[0016] The mixed solution A was added dropwise into the four-necked flask at a constant speed over 3 hours using a dropping pump, and the mixture was kept warm for 1 hour after the addition was completed.

[0017] Add the formulated amount of active hydrogen-containing amine compound and continue to react at 115° C. for 1 hour to obtain the acrylic acid-modified epoxy main resin.

[0018] In certain embodiments, the blocked isocyanate crosslinking agent in step S2 comprises the following components in parts by weight:

[0019] 40-60 parts of isocyanate,

[0020] 15-25 parts of organic solvent,

[0021] 20-40 parts of sealing agent.

[0022] In certain embodiments, the isocyanate in step S2 is an aliphatic isocyanate with good weather resistance, preferably HDI trimer; and the organic solvent in step S2 is a benzene or ketone solvent, preferably butanone.

[0023] In certain embodiments, the blocking agent in step S2 can be selected from oximes, amines, alcohol ethers, etc., preferably, oximes that can be unblocked at low temperatures and alcohol ethers that can be unblocked at relatively high temperatures are used in combination to meet the requirements of unblocking at different temperatures, so that the acrylic acid and epoxy resin will not be cured too quickly during the curing process of the electrophoretic coating and will not have time to self-stratify, thereby affecting the weather resistance. The combination of methyl ethyl ketone oxime and diethylene glycol butyl ether is particularly preferred.

[0024] In certain embodiments, the preparation method of the blocked isocyanate crosslinker in step S2 is:

[0025] Mix the sealing agents in the formula amount to obtain a mixed solution B;

[0026] Add the formulated amount of isocyanate and organic solvent into a four-necked flask and heat to 72°C;

[0027] The mixed solution B was added dropwise into a four-necked flask. The material temperature was controlled not to be higher than 75° C. during the addition process. The temperature was kept warm for 1 hour after the addition was completed. No obvious NCO peak was detected by infrared spectroscopy, indicating that a blocked isocyanate crosslinking agent was obtained.

[0028] In certain embodiments, the emulsion in step S3 comprises the following components in parts by weight:

[0029]

[0030] In certain embodiments, the neutralizing agent in step S3 is acetic acid, which has moderate acidity and good neutralization effect.

[0031] In certain embodiments, the emulsion in step S3 is prepared by:

[0032] The acrylic modified epoxy main resin in S1 and the blocked isocyanate crosslinker in S2 are added and heated to 55° C. and stirred for 30 minutes. A neutralizer is then added and neutralized for 30 minutes. After neutralization, pure water is added for dilution and stirring is continued for 30 minutes. A functional additive is added and stirring is continued for 30 minutes to obtain the emulsion.

[0033] On the other hand, the present invention provides a bottom-to-top cathode electrophoretic coating that meets long-term weather resistance, which is prepared by the following method:

[0034] S1, preparing acrylic acid modified epoxy main resin;

[0035] S2, preparing a blocked isocyanate cross-linking agent;

[0036] S3. Mixing the acrylic modified epoxy main resin in step S1 with the blocked isocyanate cross-linking agent in step S2 to prepare an emulsion.

[0037] The present invention has the following beneficial effects:

[0038] 1. The bottom-to-top cathode electrophoretic coating of the present invention is modified by grafting epoxy resin with acrylic acid. Unlike the traditional cold splicing scheme, the electrophoretic tank liquid components are stable and the long-term weather resistance of the product will not be affected by the imbalance of the epoxy and acrylic acid ratio;

[0039] 2. The acrylic modified epoxy main resin of the present invention uses a polymerizable light stabilizer. The light stabilizer is introduced into the main resin, which perfectly solves the migration problem caused by the addition of the light stabilizer in the coating and provides the product with long-term weather resistance;

[0040] 3. The blocked isocyanate crosslinker of the present invention uses two blocking agents with different deblocking temperatures, which can achieve self-delamination of epoxy acrylic acid while meeting the low-temperature curing requirements, providing the product with long-term weather resistance. DETAILED DESCRIPTION

[0041] The present invention will be further described in detail below through embodiments.

[0042] Example 1

[0043] A bottom-to-top cathode electrophoretic coating that meets long-term weather resistance is prepared by the following preparation method:

[0044] S1. Preparation of acrylic acid modified epoxy resin:

[0045] According to parts by weight, 2 parts of BPO, 6 parts of methyl methacrylate, 9 parts of hydroxyethyl methacrylate, 11 parts of butyl acrylate, 6 parts of glycidyl methacrylate, 2 parts of isobornyl methacrylate, and 2 parts of LA-82 were added and mixed to obtain a mixed solution A;

[0046] 35 parts of epoxy resin and 20 parts of propylene glycol methyl ether were added to a four-necked flask and heated to 115°C;

[0047] The mixed solution A described in step A was added dropwise into the four-necked flask at a constant speed over 3 hours using a dropping pump, and the mixture was kept warm for 1 hour after the addition was completed;

[0048] After the heat preservation is completed, 4 parts of methylethanolamine are added and the reaction is continued at 115° C. for 1 hour to obtain the acrylic acid-modified epoxy main resin.

[0049] Example 2

[0050] A bottom-to-top cathode electrophoretic coating that meets long-term weather resistance is prepared by the following preparation method:

[0051] S1. Preparation of acrylic acid modified epoxy resin:

[0052] According to parts by weight, 2 parts of BPO, 6 parts of methyl methacrylate, 9 parts of hydroxyethyl methacrylate, 11 parts of butyl acrylate, 6 parts of glycidyl methacrylate, 2 parts of isobornyl methacrylate, and 2 parts of CHIGUARD 323 were added and mixed to obtain a mixed solution A;

[0053] 35 parts of epoxy resin and 20 parts of propylene glycol methyl ether were added to a four-necked flask and heated to 115°C;

[0054] The mixed solution A described in step A was added dropwise into the four-necked flask at a constant speed over 3 hours using a dropping pump, and the mixture was kept warm for 1 hour after the addition was completed;

[0055] After the heat preservation is completed, 4 parts of methylethanolamine are added and the reaction is continued at 115° C. for 1 hour to obtain the acrylic acid-modified epoxy main resin.

[0056] Example 3

[0057] A bottom-to-top cathode electrophoretic coating that meets long-term weather resistance is prepared by the following preparation method:

[0058] S1. Preparation of acrylic acid modified epoxy resin:

[0059] According to parts by weight, 2 parts of BPO, 6 parts of methyl methacrylate, 9 parts of hydroxyethyl methacrylate, 11 parts of butyl acrylate, 6 parts of glycidyl methacrylate, 2 parts of isobornyl methacrylate, 1 part of LA-82, and 1 part of CHIGUARD 323 were added and mixed to obtain a mixed solution A;

[0060] 35 parts of epoxy resin and 20 parts of propylene glycol methyl ether were added to a four-necked flask and heated to 115°C;

[0061] The mixed solution A described in step A was added dropwise into the four-necked flask at a constant speed over 3 hours using a dropping pump, and the mixture was kept warm for 1 hour after the addition was completed;

[0062] After the heat preservation is completed, 4 parts of methylethanolamine are added and the reaction is continued at 115° C. for 1 hour to obtain the acrylic acid-modified epoxy main resin.

[0063] Example 4

[0064] A bottom-to-top cathode electrophoretic coating that meets long-term weather resistance is prepared by the following preparation method:

[0065] S1. Preparation of acrylic acid modified epoxy resin:

[0066] 1.5 parts of BPO, 4 parts of methyl methacrylate, 8 parts of hydroxyethyl methacrylate, 8 parts of butyl acrylate, 4 parts of glycidyl methacrylate, 2 parts of isobornyl methacrylate, and 1 part of LA-82 were added and mixed in parts by weight to obtain a mixed solution A;

[0067] 30 parts of epoxy resin and 15 parts of propylene glycol methyl ether were added into a four-necked flask and heated to 115°C;

[0068] The mixed solution A described in step A was added dropwise into the four-necked flask at a constant speed over 3 hours using a dropping pump, and the mixture was kept warm for 1 hour after the addition was completed;

[0069] After the heat preservation is completed, 3 parts of methylethanolamine are added and the reaction is continued at 115° C. for 1 hour to obtain the acrylic acid-modified epoxy main resin.

[0070] Example 5

[0071] A bottom-to-top cathode electrophoretic coating that meets long-term weather resistance is prepared by the following preparation method:

[0072] S1. Preparation of acrylic acid modified epoxy resin:

[0073] 2.5 parts of BPO, 8 parts of methyl methacrylate, 12 parts of hydroxyethyl methacrylate, 12 parts of butyl acrylate, 8 parts of glycidyl methacrylate, 3 parts of isobornyl methacrylate, and 2 parts of LA-82 were added and mixed in parts by weight to obtain a mixed solution A;

[0074] Add 50 parts of epoxy resin and 25 parts of propylene glycol methyl ether into a four-necked flask and heat it to 115°C;

[0075] The mixed solution A described in step A was added dropwise into the four-necked flask at a constant speed over 3 hours using a dropping pump, and the mixture was kept warm for 1 hour after the addition was completed;

[0076] After the heat preservation is completed, 7 parts of methylethanolamine are added and the reaction is continued at 115° C. for 1 hour to obtain the acrylic acid-modified epoxy main resin.

[0077] Comparative Example 1

[0078] A bottom-to-top cathode electrophoretic coating that meets long-term weather resistance is prepared by the following preparation method:

[0079] S1. Preparation of acrylic acid modified epoxy resin:

[0080] According to parts by weight, 2 parts of BPO, 6 parts of methyl methacrylate, 9 parts of hydroxyethyl methacrylate, 11 parts of butyl acrylate, 6 parts of glycidyl methacrylate, and 2 parts of isobornyl methacrylate were added to obtain a mixed solution A;

[0081] 35 parts of epoxy resin and 20 parts of propylene glycol methyl ether were added to a four-necked flask and heated to 115°C;

[0082] The mixed solution A described in step A was added dropwise into the four-necked flask at a constant speed over 3 hours using a dropping pump, and the mixture was kept warm for 1 hour after the addition was completed;

[0083] After the heat preservation is completed, 4 parts of methylethanolamine are added and the reaction is continued at 115°C for 1 hour. After the reaction is completed, the temperature is lowered to 80°C and 1 part of LA-82 and 1 part of CHIGUARD 323 are added in sequence and mixed for 30 minutes to obtain the acrylic modified epoxy main resin.

[0084] Example 6

[0085] A bottom-to-top cathode electrophoretic coating that meets long-term weather resistance is prepared by the following preparation method:

[0086] S2. Preparation of blocked isocyanate crosslinking agent:

[0087] 15.5 parts of methyl ethyl ketone oxime and 14.5 parts of diethylene glycol butyl ether were mixed to obtain a mixed solution B;

[0088] 20 parts of butanone and 40 parts of HDI trimer were added to a four-necked flask and heated to 72°C;

[0089] The mixed solution B was added dropwise into a four-necked flask. The material temperature was controlled not to be higher than 75° C. during the addition process. The temperature was kept warm for 1 hour after the addition was completed. No obvious NCO peak was detected by infrared spectroscopy, indicating that a blocked isocyanate crosslinking agent was obtained.

[0090] Example 7

[0091] A bottom-to-top cathode electrophoretic coating that meets long-term weather resistance is prepared by the following preparation method:

[0092] S2. Preparation of blocked isocyanate crosslinking agent:

[0093] 10.0 parts of methyl ethyl ketone oxime and 10.0 parts of diethylene glycol butyl ether were mixed to obtain a mixed solution B;

[0094] 15 parts of butanone and 50 parts of HDI trimer were added to a four-necked flask and heated to 72°C;

[0095] The mixed solution B was added dropwise into a four-necked flask. The material temperature was controlled not to be higher than 75° C. during the addition process. The temperature was kept warm for 1 hour after the addition was completed. No obvious NCO peak was detected by infrared spectroscopy, indicating that a blocked isocyanate crosslinking agent was obtained.

[0096] Example 8

[0097] A bottom-to-top cathode electrophoretic coating that meets long-term weather resistance is prepared by the following preparation method:

[0098] S2. Preparation of blocked isocyanate crosslinking agent:

[0099] 15.0 parts of methyl ethyl ketone oxime and 15.0 parts of diethylene glycol butyl ether were mixed to obtain a mixed solution B;

[0100] 25 parts of butanone and 60 parts of HDI trimer were added to a four-necked flask and heated to 72°C;

[0101] The mixed solution B was added dropwise into a four-necked flask. The material temperature was controlled not to be higher than 75° C. during the addition process. The temperature was kept warm for 1 hour after the addition was completed. No obvious NCO peak was detected by infrared spectroscopy, indicating that a blocked isocyanate crosslinking agent was obtained.

[0102] Examples 9-12

[0103] A bottom-to-top cathode electrophoretic coating that meets long-term weather resistance is prepared by the following preparation method:

[0104] S3. Preparation of cathode electrophoretic emulsion:

[0105] The S1 main resin and S2 cross-linking agent are added in the formula amount in sequence, and the temperature is raised to 55° C. and stirred for 30 minutes. The neutralizer is then added and neutralized for 30 minutes. After the neutralization is completed, pure water is added to dilute the mixture and the stirring is continued for 30 minutes. The functional additive is then added and stirred for 30 minutes to obtain the emulsion.

[0106] The methods for preparing electrophoretic emulsions in Examples 9-12 are the same, except that the acrylic acid-modified epoxy resin used in step S1 is different, as shown in the table below:

[0107] Example 9 Example 10 Example 11 Example 12 Example 1 26 Example 2 26 Example 3 26 Comparative Example 1 26 Example 6 10 10 10 10 Neutralizer 3 3 3 3 pure water 60 60 60 60 Functional additives 1 1 1 1 Total 100 100 100 100

[0108] Performance Testing

[0109] The emulsions obtained in Examples 9-12 were mixed with our company's HR-6000 bottom-to-top integrated black paste, with the ratio of color paste: emulsion: pure water = 1:6:8. After the bath solution was aged normally for 24 hours, electrophoresis was performed according to conventional electrophoresis conditions and baked at 170°C for 20 minutes to form a coating film that meets long-term weather resistance on the outer surface of the workpiece. The main technical indicators of the sample were tested:

[0110] Table 1

[0111]

[0112]

[0113] As shown in Table 1, Example 9 used only the polymerizable hindered amine component LA-82; Example 10 used only the polymerizable UV absorber component CHIGUARD 323; and Example 11 used a combination of LA-82 and CHIGUARD 323, resulting in better long-term weather resistance. This is because LA-82 is a hindered amine light stabilizer and CHIGUARD 323 is a UV absorber. When used together, they produce a synergistic effect (UV absorbers slow the generation rate of free radicals after exposure to light, while hindered amine light stabilizers can slow the rate of oxidative degradation caused by free radicals. Furthermore, UV absorbers do not act on the outer surface of the coating, while hindered amine light stabilizers can effectively scavenge free radicals on the coating surface). In Example 12, LA-82 and CHIGUARD 323 were added after the amination reaction and were not grafted onto the epoxy resin, resulting in poor long-term weather resistance.

[0114] In summary, the present invention has the following advantages:

[0115] 1. The bottom-to-top cathode electrophoretic coating of the present invention is modified by grafting epoxy resin with acrylic acid. Unlike the traditional cold splicing scheme, the electrophoretic tank liquid components are stable and the long-term weather resistance of the product will not be affected by the imbalance of the epoxy and acrylic acid ratio;

[0116] 2. The acrylic modified epoxy main resin of the present invention uses a polymerizable light stabilizer. The light stabilizer is introduced into the main resin, which perfectly solves the migration problem caused by the addition of the light stabilizer in the coating and provides the product with long-term weather resistance;

[0117] 3. The blocked isocyanate crosslinker of the present invention uses two blocking agents with different deblocking temperatures, which can achieve self-delamination of epoxy acrylic acid while meeting the low-temperature curing requirements, providing the product with long-term weather resistance.

[0118] The above description is only a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several modifications and improvements without departing from the inventive concept of the present invention, and these should also be considered within the scope of protection of the invention.

Claims

1. A method for preparing a bottom-to-top cathode electrophoretic coating that meets long-term weather resistance, characterized in that: The following steps are involved: S1, preparing acrylic acid modified epoxy main resin; S2, preparing a blocked isocyanate cross-linking agent; S3, mixing the acrylic modified epoxy main resin in step S1 with the blocked isocyanate cross-linking agent in step S2 to prepare an emulsion.

2. The method for preparing a bottom-to-top cathode electrophoretic coating that meets long-term weather resistance according to claim 1, characterized in that: The acrylic acid-modified epoxy main resin in step S1 includes the following components in parts by weight:

3. The method for preparing a bottom-to-top cathode electrophoretic coating that meets long-term weather resistance according to claim 2, characterized in that: The epoxy equivalent of the epoxy resin in step S1 is 184-1200, preferably a bisphenol A epoxy resin with an epoxy equivalent of 300-800, and particularly preferably a bisphenol A epoxy resin with an epoxy equivalent of 450-560; the organic solvent in step S1 is one of xylene, methyl isobutyl ketone, propylene glycol methyl ether, propylene glycol butyl ether, and ethylene glycol butyl ether, and preferably propylene glycol methyl ether; the initiator in step S1 is a peroxide initiator, and preferably BPO; the active hydrogen-containing amine compound in step S1 is a monovalent secondary amine, and preferably one of ketimine, alcoholamine, and alkylamine, and particularly preferably methylethanolamine.

4. The method for preparing a bottom-to-top cathode electrophoretic coating that meets long-term weather resistance according to claim 2, characterized in that: The preparation method of the acrylic acid-modified epoxy main resin in step S1 is: Mixing the initiator, methyl methacrylate, hydroxyethyl methacrylate, butyl acrylate, glycidyl methacrylate, isobornyl methacrylate, and a polymerizable light stabilizer in a formulated amount to obtain a mixed solution A; Add the formulated amount of epoxy resin and organic solvent into a four-necked flask and heat it to 115°C; The mixed solution A was added dropwise into the four-necked flask at a constant speed over 3 hours by a dropping pump, and the temperature was kept at room temperature for 1 hour after the addition was completed; Add the formulated amount of active hydrogen-containing amine compound and continue to react at 115° C. for 1 hour to obtain an acrylic acid-modified epoxy main resin.

5. The method for preparing a bottom-to-top cathode electrophoretic coating that meets long-term weather resistance according to claim 1, characterized in that: The blocked isocyanate cross-linking agent in step S2 includes the following components in parts by weight: 40-60 parts of isocyanate, 15-25 parts of organic solvent, 20-40 parts of sealing agent.

6. The method for preparing a bottom-to-top cathode electrophoretic coating that meets long-term weather resistance according to claim 5, characterized in that: The isocyanate in step S2 is an aliphatic isocyanate with good weather resistance, preferably HDI trimer; the organic solvent in step S2 is a benzene or ketone solvent, preferably butanone.

7. The method for preparing a bottom-to-top cathode electrophoretic coating that meets long-term weather resistance according to claim 5, characterized in that: The preparation method of the blocked isocyanate cross-linking agent in step S2 is: Mix the sealing agents in the formula amount evenly to obtain a mixed solution B; Add the formulated amount of isocyanate and organic solvent into a four-necked flask and heat it to 72°C; The mixed solution B was added dropwise into a four-necked flask. During the addition process, the material temperature was controlled not to be higher than 75° C. After the addition was completed, the temperature was kept warm for 1 hour. When infrared detection showed no obvious NCO peak, the blocked isocyanate crosslinking agent was obtained.

8. The method for preparing a bottom-to-top cathode electrophoretic coating that meets long-term weather resistance according to claim 1, characterized in that: The emulsion in step S3 includes the following components by weight:

9. The method for preparing a bottom-to-top cathode electrophoretic coating that meets long-term weather resistance according to claim 8, characterized in that: The preparation method of the emulsion in step S3 is: The acrylic modified epoxy main resin in S1 and the blocked isocyanate crosslinking agent in S2 are added, and the temperature is raised to 55° C. and stirred for 30 minutes. A neutralizer is added for neutralization for 30 minutes. After the neutralization is completed, pure water is added for dilution, and stirring is continued for 30 minutes. A functional additive is added and stirring is continued for 30 minutes to obtain the emulsion.

10. A bottom-to-top cathode electrophoretic coating that meets long-term weather resistance, characterized in that: The compound is prepared by the preparation method described in any one of claims 1 to 9.

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