A solvent-based primer coating for high-roughness body metal substrates, and a method of preparing and applying the same

Abstract

The application relates to the technical field of coatings, in particular to a solvent-based primer coating for high-roughness automobile body metal substrates and a preparation method and application thereof. The primer coating comprises the following components in mass fraction: 12-16% of polyester resin, 5-10% of amino resin, 1-3% of isocyanate, 2-3% of SCA modified anti-sagging resin, 40-60% of color paste, 4-8% of CAB-381-0.5 cellulose acetate butyrate, 2-6% of CAB-381-20 cellulose acetate butyrate, 0.3-0.7% of leveling agent, 0.3-0.7% of wet dispersant, 1-3% of defoaming agent, 5-15% of lipid solvent and 0.5-1.5% of alcohol solvent. Compared with the prior art, the primer coating can improve the workability of products with poor roughness of substrates, improve the overall appearance level, and improve the appearance level of the composite coating: long wave Lw is reduced from 15 to 5; short wave Sw is reduced from 30 to 20; DOI is improved from 80 to 88; and R is improved from 5 to 7.

Description

Technical Field

[0001] This invention relates to the field of coating technology, specifically to a solvent-based primer coating for high-roughness automotive metal substrates, its preparation method, and its application. Background Technology

[0002] With the development of the automotive industry in recent years, various types of automotive products have emerged, resulting in differences in raw material conditions, bodywork processes, and processing levels. In specific areas, low-end automotive products (four-wheeled low-speed vehicles) often experience poor surface roughness on the body-in-white and on the substrate after electrophoresis due to uncertainties during the vehicle painting process. Existing automotive coating products are often unable to adapt to this poor surface roughness, frequently leading to poor painting effects and a series of problems such as poor product coating appearance. Summary of the Invention

[0003] To overcome the shortcomings of existing automotive coatings, which often result in poor coating effects and poor product appearance due to their inability to adapt to the surface roughness of the car body and substrates after electrophoresis, this invention provides a solvent-based primer coating for high-roughness automotive metal substrates, its preparation method, and its application. This invention's automotive primer coating, through formulation design and optimization, focuses on addressing the reality of poor surface roughness of the car body and substrates after electrophoresis. By improving the primer product's filling and wetting properties for the substrate, and enhancing the primer coating's modification and leveling effects on the substrate, it comprehensively improves the overall coating appearance and effect of the vehicle, and brings the coating level of low-end automotive products (four-wheeled low-speed vehicles) close to or on par with that of ordinary passenger car products.

[0004] One of the technical solutions of the present invention provides a solvent-based primer coating for a high-roughness automotive metal substrate. The primer coating comprises the following components in parts by weight: 12-16 parts polyester resin, 5-10 parts amino resin, 1-3 parts isocyanate, 2-3 parts SCA-modified anti-sagging resin, 40-60 parts color paste, 4-8 parts CAB-381-0.5 cellulose acetate butyrate, 2-6 parts CAB-381-20 cellulose acetate butyrate, 0.3-0.7 parts leveling agent, 0.3-0.7 parts wetting and dispersing agent, 1-3 parts defoamer, 5-15 parts lipid solvent, and 0.5-1.5 parts alcohol solvent.

[0005] In the primer coating components of this invention: polyester resin is the main film-forming resin, amino resin is mainly cross-linked and cured with polyester resin, isocyanate is used to provide better flexibility, SCA modified anti-sagging resin is mainly used to provide anti-sagging properties, color paste is used for coloring and also plays a covering role, CAB-381-0.5 cellulose acetate butyrate and CAB-381-20 cellulose acetate butyrate are used to improve the thixotropic properties, anti-settling properties and adjust the humidity of the wet film of the coating, leveling agent is mainly beneficial to the leveling of the wet film and improves the appearance, and wetting and dispersing agent is beneficial to the wetting and dispersion of pigments and the wetting of the substrate.

[0006] The present invention also limits the weight proportions of each component of the primer coating. When each component is within the above-mentioned limits, the performance of the primer coating of the present invention is optimal.

[0007] Preferably, the primer coating comprises the following components in parts by weight: 14 parts polyester resin, 7.5 parts amino resin, 2 parts isocyanate, 2.5 parts SCA modified anti-sagging resin, 50 parts color paste, 6 parts CAB-381-0.5 cellulose acetate butyrate, 4 parts CAB-381-20 cellulose acetate butyrate, 0.5 parts leveling agent, 0.5 parts wetting and dispersing agent, 2 parts defoamer, 10 parts lipid solvent, and 1 part alcohol solvent.

[0008] Furthermore, the color paste comprises the following components in parts by weight: 25-30 parts polyester resin, 5-10 parts ester solvent, 1-5 parts benzene solvent, 5-10 parts polyester resin wax paste, 1-3 parts wetting and dispersing agent, and 50-60 parts titanium dioxide. Here, the parts by weight of each component are relative to the weight of the color paste.

[0009] Preferably, the color paste comprises the following components in parts by weight: 28 parts polyester resin, 6 parts ester solvent, 2 parts benzene solvent, 6 parts polyester resin wax paste, 2 parts wetting and dispersing agent, and 56 parts titanium dioxide.

[0010] Furthermore, the ester solvent is one or more of butyl acetate, propylene glycol methyl ether acetate, or dimethyl ester (DBE).

[0011] Furthermore, the benzene solvent is xylene.

[0012] Furthermore, the wetting and dispersing agent is a BYK-161 modified polyurethane solution or a BYK344 polyether modified polydimethylsiloxane solution. The wetting and dispersing agent used is a high molecular weight block copolymer solution containing pigment-affinity groups. Through steric hindrance stabilization, it prevents pigment re-flocculation, significantly improves pigment wettability, reduces the grinding time, improves coating gloss and leveling properties, lowers coating viscosity, and avoids thixotropy.

[0013] Furthermore, the leveling agent is BYK344 leveling agent from Germany.

[0014] Furthermore, the wetting and dispersing agent is BYK-161 dispersant from Germany.

[0015] Furthermore, the defoamer is BYK-141SG.

[0016] Furthermore, the lipid solvent is one or more of butyl acetate, ethyl acetate, propylene glycol methyl ether acetate, or dimethyl ester (DBE).

[0017] Furthermore, the alcohol solvent is one or both of n-butanol and methanol.

[0018] The second technical solution of the present invention provides a method for preparing the solvent-based primer coating for the above-mentioned high-roughness automotive metal substrate, the method comprising:

[0019] The desired product is obtained by mixing polyester resin, amino resin, isocyanate, SCA modified anti-sagging resin, color paste, CAB-381-0.5 cellulose acetate butyrate, CAB-381-20 cellulose acetate butyrate, leveling agent, wetting and dispersing agent, defoamer, lipid solvent and alcohol solvent.

[0020] The third technical solution of the present invention provides the application of the solvent-based primer coating on the above-mentioned high-roughness car body metal substrate. The primer coating is applied to the high-roughness car body metal substrate and coated on the car body metal substrate.

[0021] The beneficial effects of this invention are as follows:

[0022] The components of this invention's primer coating work synergistically to improve workability on substrates with poor roughness, enhance overall appearance, and improve the appearance of composite coatings: long-wavelength (Lw) decreases from 15-20 to 5-12; short-wavelength (Sw) decreases from 40-50 to 20-38; DOI (Distinctness of Indices) increases from 77-82 to 85-92; and R (Orange Peel Index) increases from 5-6 to 7-9. This invention's automotive primer improves the filling and wetting properties of the primer on the substrate, strengthens the modification and leveling effect of the primer coating, thereby comprehensively improving the overall appearance and effect of vehicle coatings, and bringing the coating level of low-end automotive products (low-speed four-wheeled vehicles) close to or on par with that of ordinary passenger vehicles. Detailed Implementation

[0023] In the following embodiments, unless otherwise specified, the raw materials or processing techniques used are conventional commercially available raw materials or conventional processing techniques in the art.

[0024] In the following embodiments, the SCA-modified anti-sagging resin used was purchased from Allnex SCA Setal 91796.

[0025] In the following embodiments, the polyester resin used was purchased from Tongde, model AK3020.

[0026] In the following embodiments, the polyester resin wax paste used was purchased from DISPARON, model VOK-4200-20.

[0027] Example 1

[0028] This embodiment prepares a solvent-based primer coating for high-roughness automotive metal substrates. The following components in parts by weight are mixed evenly: 14 parts polyester resin, 7.5 parts amino resin, 2 parts isocyanate, 2.5 parts SCA modified anti-sagging resin, 50 parts color paste, 6 parts CAB-381-0.5 cellulose acetate butyrate, 4 parts CAB-381-20 cellulose acetate butyrate, 0.5 parts leveling agent (BYK344 leveling agent from Germany), 0.5 parts wetting and dispersing agent (BYK-161 dispersing agent from Germany), 2 parts defoamer (BYK-141SG), 10 parts lipid solvent (butyl acetate), and 1 part alcohol solvent (n-butanol).

[0029] The components of the above color paste, and the weight parts of each component, are as follows: 28 parts of polyester resin, 6 parts of ester solvent (a mixture of propylene glycol methyl ether acetate and dimethyl ester DBE, in a volume ratio of 1:1), 2 parts of xylene, 6 parts of polyester resin wax paste, 2 parts of wetting and dispersing agent (BYK-161 modified polyurethane solution), and 56 parts of titanium dioxide.

[0030] Current mainstream passenger vehicle painting requirements stipulate a surface roughness Ra ≤ 0.3 after pretreatment and electrophoresis. However, a customer of low-speed four-wheeled vehicles, whose production line and model have just commenced production, has body-in-white roughness and post-electrophoresis roughness Ra values ​​between 0.4 and 0.6. Through several rounds of on-site adjustments, the customer's overall vehicle appearance is found to have long-wave Lw values ​​between 15 and 20, and short-wave Sw values ​​between 40 and 50, severely impacting the overall paint finish and visual appearance.

[0031] Because the customer could not improve the condition of the body-in-white and electrophoretic coating in a short period of time, there was an urgent need for a mid-coat primer product to compensate for this condition (poor roughness). The primer coating prepared in this embodiment was applied to the vehicle body (long-wave Lw value 15, short-wave Sw value 40). After testing, the appearance level of the composite coating was as follows: long-wave Lw: decreased from 15 to 5; short-wave Sw: decreased from 40 to 20; DOI: increased from 80 to 88; R: increased from 5 to 7.

[0032] Example 2

[0033] This embodiment prepares a solvent-based primer coating for high-roughness automotive metal substrates. The following components in parts by weight are mixed evenly: 12 parts polyester resin, 5 parts amino resin, 1 part isocyanate, 2 parts SCA modified anti-sagging resin, 40 parts color paste, 4 parts CAB-381-0.5 cellulose acetate butyrate, 2 parts CAB-381-20 cellulose acetate butyrate, 0.3 parts leveling agent (BYK344 leveling agent from Germany), 0.3 parts wetting and dispersing agent (BYK-161 dispersing agent from Germany), 1 part defoamer (BYK-141SG), 5 parts lipid solvent (a mixture of butyl acetate and ethyl acetate in a volume ratio of 1:1), and 0.5 parts alcohol solvent (methanol).

[0034] The components of the above color paste, and the weight parts of each component, are as follows: 25 parts polyester resin, 5 parts butyl acetate, 1 part xylene, 5 parts polyester resin wax paste, 1 part wetting and dispersing agent (BYK344 polyether modified polydimethylsiloxane solution), and 50 parts titanium dioxide.

[0035] Current mainstream passenger vehicle painting requirements stipulate a surface roughness Ra ≤ 0.3 after pretreatment and electrophoresis. However, a customer of low-speed four-wheeled vehicles, whose production line and model have just commenced production, has body-in-white roughness and post-electrophoresis roughness Ra values ​​between 0.4 and 0.6. Through several rounds of on-site adjustments, the customer's overall vehicle appearance is found to have long-wave Lw values ​​between 15 and 20, and short-wave Sw values ​​between 40 and 50, severely impacting the overall paint finish and visual appearance.

[0036] Because the customer was unable to improve the condition of the body-in-white and electrophoretic coating in a short period of time, a mid-coat primer product was urgently needed to compensate for this condition (poor roughness). The primer coating prepared in this embodiment was applied to the vehicle body (long-wave Lw value 20, short-wave Sw value 50). Testing showed the following composite coating appearance levels: long-wave Lw: decreased from 20 to 10; short-wave Sw: decreased from 50 to 35; DOI: increased from 82 to 92; R: increased from 6 to 9.

[0037] Example 3

[0038] This embodiment prepares a solvent-based primer coating for high-roughness automotive metal substrates. The following components in parts by weight are mixed evenly: 16 parts polyester resin, 10 parts amino resin, 3 parts isocyanate, 3 parts SCA modified anti-sagging resin, 60 parts color paste, 8 parts CAB-381-0.5 cellulose acetate butyrate, 6 parts CAB-381-20 cellulose acetate butyrate, 0.7 parts leveling agent (BYK344 leveling agent from Germany), 0.7 parts wetting and dispersing agent (BYK-161 dispersing agent from Germany), 3 parts defoamer (BYK-141SG from Germany), 15 parts lipid solvent (a mixture of butyl acetate, ethyl acetate, and propylene glycol methyl ether acetate in a volume ratio of 1:1:1), and 1.5 parts alcohol solvent (a mixture of n-butanol and methanol in a volume ratio of 1:1).

[0039] The components of the above color paste, and the weight parts of each component, are as follows: 30 parts polyester resin, 10 parts propylene glycol methyl ether acetate, 5 parts xylene, 10 parts polyester resin wax paste, 3 parts wetting and dispersing agent (BYK-161 modified polyurethane solution), and 60 parts titanium dioxide.

[0040] Current mainstream passenger vehicle painting requirements stipulate a surface roughness Ra ≤ 0.3 after pretreatment and electrophoresis. However, a customer of low-speed four-wheeled vehicles, whose production line and model have just commenced production, has body-in-white roughness and post-electrophoresis roughness Ra values ​​between 0.4 and 0.6. Through several rounds of on-site adjustments, the customer's overall vehicle appearance is found to have long-wave Lw values ​​between 15 and 20, and short-wave Sw values ​​between 40 and 50, severely impacting the overall paint finish and visual appearance.

[0041] Because the customer could not improve the condition of the body-in-white and the electrophoretic coating in a short period of time, there was an urgent need for a mid-coat primer product to compensate for this condition (poor roughness). The primer coating prepared in this embodiment was applied to the vehicle body (long-wave Lw value 18, short-wave Sw value 45). After testing, the appearance level of the composite coating was as follows: long-wave Lw: decreased from 18 to 12; short-wave Sw: decreased from 45 to 38; DOI: increased from 77 to 85; R: increased from 5 to 8.

[0042] Example 4

[0043] This embodiment prepares a solvent-based primer coating for high-roughness automotive metal substrates. The following components in parts by weight are mixed evenly: 15 parts polyester resin, 8 parts amino resin, 2.5 parts isocyanate, 3 parts SCA modified anti-sagging resin, 45 parts color paste, 5 parts CAB-381-0.5 cellulose acetate butyrate, 3 parts CAB-381-20 cellulose acetate butyrate, 0.4 parts leveling agent (BYK344 leveling agent from Germany), 0.6 parts wetting and dispersing agent (BYK-161 dispersing agent from Germany), 1.5 parts defoamer (BYK-141SG from Germany), 6 parts lipid solvent (a mixture of butyl acetate, ethyl acetate, and propylene glycol methyl ether acetate in a volume ratio of 1:1:1), and 0.6 parts alcohol solvent (a mixture of n-butanol and methanol in a volume ratio of 1:1).

[0044] The components of the above color paste, and the weight parts of each component, are as follows: 30 parts polyester resin, 10 parts propylene glycol methyl ether acetate, 5 parts xylene, 10 parts polyester resin wax paste, 3 parts wetting and dispersing agent (BYK-161 modified polyurethane solution), and 60 parts titanium dioxide.

[0045] Current mainstream passenger vehicle painting requirements stipulate a surface roughness Ra ≤ 0.3 after pretreatment and electrophoresis. However, a customer of low-speed four-wheeled vehicles, whose production line and model have just commenced production, has body-in-white roughness and post-electrophoresis roughness Ra values ​​between 0.4 and 0.6. Through several rounds of on-site adjustments, the customer's overall vehicle appearance is found to have long-wave Lw values ​​between 15 and 20, and short-wave Sw values ​​between 40 and 50, severely impacting the overall paint finish and visual appearance.

[0046] Because the customer was unable to improve the condition of the body-in-white and the electrophoretic coating in a short period of time, there was an urgent need for a mid-coat primer product to compensate for this condition (poor roughness). The primer coating prepared in this embodiment was applied to the vehicle body (long-wave Lw value 17, short-wave Sw value 48). After testing, the appearance level of the composite coating was as follows: long-wave Lw: decreased from 17 to 10; short-wave Sw: decreased from 48 to 40; DOI: increased from 79 to 87; R: increased from 5 to 8.

[0047] The above embodiments are preferred implementations of the present invention. In addition, the present invention can be implemented in other ways. Any obvious substitutions without departing from the concept of the present invention are within the protection scope of the present invention.

Claims

1. A solvent-borne primer coating for high-roughness automotive body metal substrates, characterized in that, The color paste comprises the following components in parts by weight: polyester resin 25-30 parts, ester solvent 5-10 parts, benzene solvent 1-5 parts, polyester resin wax paste 5-10 parts, wet dispersant 1-3 parts, titanium white 50-60 parts. The color paste comprises the following components in parts by weight: polyester resin 25-30 parts, ester solvent 5-10 parts, benzene solvent 1-5 parts, polyester resin wax paste 5-10 parts, wet dispersant 1-3 parts, titanium white 50-60 parts.

2. A high-roughness automotive metal substrate solvent-borne primer coating according to claim 1, characterized in that, The color paste comprises the following components in parts by weight: polyester resin 25-30 parts, ester solvent 5-10 parts, benzene solvent 1-5 parts, polyester resin wax paste 5-10 parts, wet dispersant 1-3 parts, titanium white 50-60 parts.

3. A high profile automotive body metal substrate solvent based primer coating according to claim 1, characterized in that, The leveling agent is BYK 344 leveling agent from Germany.

4. A high-roughness automotive metal substrate solvent-borne primer coating according to claim 1, characterized in that, The wet dispersant is BYK-161 dispersant from Germany.

5. A high-roughness automotive metal substrate solvent-borne primer coating according to claim 1, characterized in that, The defoaming agent is BYK-141SG.

6. A high-roughness automotive metal substrate solvent-borne primer coating according to claim 1, characterized in that, The lipid solvent is one or more of butyl acetate, ethyl acetate, propylene glycol methyl ether acetate or dimethyl ester DBE.

7. A high-roughness automotive metal substrate solvent-borne primer coating according to claim 1, characterized in that, The alcohol solvent is one or both of n-butanol or methanol.

8. A process for the preparation of a solvent-borne primer coating for high-roughness automotive metal substrates according to any one of claims 1 to 7, characterized in that, The color paste comprises the following components in parts by weight: polyester resin 25-30 parts, ester solvent 5-10 parts, benzene solvent 1-5 parts, polyester resin wax paste 5-10 parts, wet dispersant 1-3 parts, titanium white 50-60 parts. The base paint is applied to high-roughness metal substrates of vehicle bodies.

9. Use of a solvent-borne primer coating for high-roughness body metal substrates according to any one of claims 1 to 7, characterized in that ​