Conductive primer applied to polycarbonate substrate and method for preparing the same

Abstract

The application relates to a conductive primer applied to a polycarbonate base material and a preparation method thereof, raw materials of the primer include the following components in mass parts: 30-40 parts of acrylic resin, 50-60 parts of solvent, 2-4 parts of dispersing agent, 2-4 parts of conductive carbon black, 8-10 parts of rutile titanium white, 2-4 parts of modified anti-settling agent, 0.1-0.5 parts of leveling agent and 3-7 parts of curing agent; the modified anti-settling agent is polyamide modified by tea polyphenol; the method comprises the following steps: stirring tea polyphenol and a secondary solvent at a low speed to obtain tea polyphenol liquid; stirring polyamide wax and the tea polyphenol liquid at a high speed to obtain a modified anti-settling agent; stirring the acrylic resin, the solvent, the dispersing agent, the conductive carbon black, the rutile titanium white, the modified anti-settling agent, the leveling agent and the curing agent at a high speed to obtain a mixed liquid; grinding the mixed liquid to obtain the conductive primer applied to the polycarbonate base material. Compared with the prior art, the carbon black is not easy to flocculate and become coarse, and the coating system is stable.

Description

Technical Field

[0001] This invention belongs to the field of coating technology and relates to a conductive primer for polycarbonate substrates and its preparation method. Background Technology

[0002] In recent years, the rapid development of new energy vehicles has been largely due to the support of automotive design. Automotive design has become an indispensable part of the automotive industry. It encompasses details such as exterior design, interior design, safety, and aerodynamics, with exterior design being a crucial factor in attracting consumers. Exterior design includes the overall shape and color of the vehicle and its components.

[0003] Polycarbonate (PC) is widely used in many parts manufacturing plants as a highly transparent plastic substrate. However, achieving multiple colors and electrostatic spraying on this substrate is quite challenging. Because polycarbonate is a linear polyester, its carbonate groups are easily attacked by solvent molecules, leading to swelling, softening, cracking, and deformation. Directly spraying primers or color paints onto polycarbonate will also cause these defects, as typical primers and color paints contain large amounts of esters and aromatic solvents, all of which contribute to defects in polycarbonate coatings.

[0004] Patent CN109777214A discloses a graphene conductive primer and its preparation method. The primer comprises the following components in parts by weight: 35-55 parts film-forming substance, 0.01-0.8 parts graphene or graphene composite, 8-42 parts composite conductive filler, 8-42 parts titanium dioxide, 0.005-1.6 parts dispersant I, 1.5-5 parts dispersant II, 0.5-3 parts additives, and 5-20 parts solvent. However, the use of ordinary polyamide wax as an anti-settling agent in this patent still leads to carbon black flocculation. Summary of the Invention

[0005] The purpose of this invention is to overcome at least one defect of the prior art and provide a conductive primer for polycarbonate substrates and its preparation method. In this invention, carbon black is not easily flocculated and coarsened, and the coating system is stable.

[0006] The objective of this invention can be achieved through the following technical solutions: One of the technical solutions of the present invention is to provide a conductive primer for use on a polycarbonate substrate, wherein the raw materials of the primer include the following components in parts by weight: The ingredients are: 30-40 parts acrylic resin, 50-60 parts solvent, 2-4 parts dispersant, 2-4 parts conductive carbon black, 8-10 parts rutile titanium dioxide, 2-4 parts modified anti-settling agent, 0.1-0.5 parts leveling agent, and 3-7 parts curing agent. The modified anti-settling agent is a polyamide modified with tea polyphenols.

[0007] Furthermore, the acrylic resin is a hydroxyl acrylic copolymer with a solid content of 40-60 wt%, a hydroxyl value of 10-30 mg KOH / g, and a glass transition temperature (Tg) of 80-100 °C. This resin (especially the styrene monomer in a specific type) has good adhesion to polycarbonate (PC) substrates. The low hydroxyl value, when used in conjunction with a curing agent, can significantly improve the water resistance of the resin on polycarbonate substrates, while the high glass transition temperature can improve the resin's resistance to high-pressure water washing and stone impact on polycarbonate substrates.

[0008] Furthermore, the solvent is propylene glycol methyl ether.

[0009] Furthermore, the dispersant is an acrylic block copolymer, which is compatible with hydroxyacrylic acid copolymer, can be dissolved by propylene glycol methyl ether, efficiently disperses conductive carbon black, and has a low grinding viscosity.

[0010] Furthermore, the rutile titanium dioxide is sulfuric acid-based rutile titanium dioxide with inorganic surface treatment of zirconium oxide and alumina. This titanium dioxide serves as a coloring pigment, enhancing the hiding power of the primer.

[0011] Furthermore, the modified anti-settling agent is a polyamide wax modified with tea polyphenol liquid, and the mass ratio of the polyamide wax to the tea polyphenol liquid is (45~55):(45~55).

[0012] Furthermore, the tea polyphenol liquid includes tea polyphenols and a secondary solvent, wherein the secondary solvent is ethyl acetate, and the mass ratio of tea polyphenols to secondary solvent is (80~90):(10~20).

[0013] Furthermore, the leveling agent is polyether-modified polydimethylsiloxane, which reduces the surface tension of the coating, improves the wettability of the coating on the polycarbonate substrate, and reduces the formation of pinholes in the coating. The curing agent is hexamethylene diisocyanate.

[0014] One of the technical solutions of the present invention is to provide a method for preparing the conductive primer applied to a polycarbonate substrate, the method comprising the following steps: S1. Stir the tea polyphenols and auxiliary solvent at low speed to obtain a tea polyphenol solution; S2. Polyamide wax and tea polyphenol solution are stirred at high speed to obtain a modified anti-settling agent; S3. The acrylic resin, solvent, dispersant, conductive carbon black, rutile titanium dioxide, modified anti-settling agent, leveling agent and curing agent are stirred at high speed to obtain a mixture; S4. Grind the mixture to obtain a conductive primer for use on polycarbonate substrates.

[0015] Furthermore, in step S1, the temperature of the low-speed stirring is 10~40 ℃, the speed is 500~1000 r / min, and the time is 10~30 min; In step S2, the high-speed stirring temperature is 110~130 ℃, the speed is 1500~2500 r / min, and the time is 10~30 min. After high-speed stirring, the mixture is cooled to room temperature. In step S3, the high-speed stirring temperature is 10~40 ℃, the speed is 1500~2500 r / min, and the time is 10~30 min; In step S4, the grinding flow rate is 80~120 L / h, and the fineness of the primer is ≤20 μm.

[0016] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention uses propylene glycol methyl ether as a solvent for the coating system, which greatly increases the applicability of the coating on polycarbonate (PC) substrates and will not cause swelling, softening, cracking and deformation of the polycarbonate substrates, thus solving the coating defects of most coatings being easily bitten on polycarbonate substrates. (2) This invention utilizes polyamide wax modified with tea polyphenols. Tea polyphenols are complexes of polyhydroxyphenolic compounds, while polyamides form liquids at a certain temperature. When polyamides are cooled, they are compatible with tea polyphenols and form a complex. This complex utilizes the hydrogen bonds between polyamide molecules and the polyphenolic substances in tea polyphenols to form a compounding effect, which strengthens the intermolecular forces. The compounding effect is greater than that of polyamide wax alone. A network structure is formed on the carbon black surface through hydrogen bonds, which can improve the steric hindrance of carbon black molecules. At the same time, the carbon black surface is coated by the dispersant after the coating is ground to form a stable steric hindrance, which reduces the attraction of the surface energy of carbon black molecules and causes them to accumulate and flocculate, thereby improving the stability of the coating system and solving the problems of insufficient solubility of resin and dispersant, unstable coating system, and coarsening of carbon black caused by the use of a large amount of propylene glycol methyl ether. (3) In this invention, the modified anti-settling agent also has hydrogen bond adsorption on the surface of polycarbonate substrate, which strengthens the adhesion. At the same time, the coating stability brought about by carbon black dispersion and the high pressure water washing performance of the conductive primer are excellent, which reflects the advantages of tea polyphenol modified polyamide wax compared with polyamide wax alone. Detailed Implementation

[0017] The present invention will now be described in detail with reference to specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0018] Unless otherwise specified, the equipment used in the following embodiments is conventional equipment in the art; unless otherwise specified, the reagents used are commercially available products or prepared by conventional methods in the art. In the following embodiments, unless otherwise described in detail, conventional experimental methods in the art can be used.

[0019] Unless otherwise specified, the following procedures are generally performed at room temperature and atmospheric pressure.

[0020] In the following examples, the acrylic resin used was Dongsheng Chemical ESB-1205 hydroxy acrylic copolymer with a solid content of 50±1 wt%, a hydroxyl value of 20 mg KOH / g, and a glass transition temperature (Tg) of 90 ℃. The solvent used was propylene glycol methyl ether, the dispersant used was EFKA4310 acrylic block copolymer, the conductive carbon black used was PRINTEX XE2B, the rutile titanium dioxide used was LOMON R-996 zirconia and alumina inorganic surface-treated rutile titanium dioxide obtained by the sulfuric acid process, the modified anti-settling agent used was DISPARON 6900-20X polyamide wax modified with tea polyphenols, the unmodified anti-settling agent used was DISPARON 6900-20X polyamide wax, the auxiliary solvent used was ethyl acetate, the leveling agent used was BYK333 polyether modified polydimethylsiloxane, and the curing agent used was Bayer 3390 hexamethylene diisocyanate trimer.

[0021] Example 1: A conductive primer for use on polycarbonate substrates, comprising the following components in specific parts by weight: The mixture consists of 30 parts acrylic resin, 50 parts solvent, 2 parts dispersant, 2 parts conductive carbon black, 10 parts rutile titanium dioxide, 2 parts modified anti-settling agent, 0.1 parts leveling agent, and 5 parts curing agent.

[0022] The specific steps of the above-mentioned method for preparing conductive primer applied to polycarbonate substrates are as follows: S1. Add tea polyphenols and auxiliary solvents into a stirred tank at a mass ratio of 90:10 and stir at low speed of 750 r / min for 20 min at room temperature to obtain tea polyphenol solution. S2. Heat the mixing vessel to 120 ℃ using an oil bath, add polyamide wax and tea polyphenol liquid into the mixing vessel at a mass ratio of 45:55, stir at a constant temperature and high speed of 2000 r / min for 20 min, and cool to room temperature to obtain the modified anti-settling agent. S3. Add acrylic resin, solvent, dispersant, conductive carbon black, rutile titanium dioxide, modified anti-settling agent, leveling agent and curing agent into a mixing tank, and stir at high speed of 2000 r / min for 20 min at room temperature to obtain a mixture. S4. Place the mixture on a horizontal grinding mill with a grinding flow rate of 100 L / h and circulate the grinding to a fineness of ≤15 μm to obtain a conductive primer for use on polycarbonate substrates.

[0023] The above primer was subjected to the following tests or experiments, and the test or experiment results were then analyzed.

[0024] Experimental Example 1: The primer and the coating film obtained by electrostatic spraying on the polycarbonate substrate were tested for cross-cut adhesion, water resistance, high-pressure water washing, gravel impact, dry film resistance and storage stability. The test results are shown in Table 1.

[0025] Table 1 Test results of primer and paint film in Example 1 As shown in Table 1, a modified anti-settling agent was used in this embodiment. It can be seen that the high-pressure water washing performance of the coating is improved. At the same time, after storage at 50 °C for 1 month, the fineness is still maintained below 15 μm, and the storage stability is also significantly improved. In addition, the adhesion, water resistance, crushed stone impact performance and dry film resistance performance also meet the requirements.

[0026] Example 2: A conductive primer for polycarbonate substrates is basically the same as in Example 1, except that the proportions of the components are different. The specific components by weight are as follows: The mixture contains 33 parts acrylic resin, 53 parts solvent, 2.8 parts dispersant, 2.8 parts conductive carbon black, 9.2 parts rutile titanium dioxide, 2.8 parts modified anti-settling agent, 0.2 parts leveling agent, and 5 parts curing agent.

[0027] The preparation method of the conductive primer applied to polycarbonate substrate described above is basically the same as that in Example 1, except that the proportions of each component in steps S1 and S2 are different. The specific steps are as follows: S1. Add tea polyphenols and auxiliary solvents into a stirred tank at a mass ratio of 87:13, and stir at low speed of 750 r / min for 20 min at room temperature to obtain tea polyphenol solution. S2. Heat the mixing vessel to 120 ℃ using an oil bath, add polyamide wax and tea polyphenol liquid into the mixing vessel at a mass ratio of 50:50, stir at a constant temperature and high speed of 2000 r / min for 20 min, and cool to room temperature to obtain the modified anti-settling agent. S3. Add acrylic resin, solvent, dispersant, conductive carbon black, rutile titanium dioxide, modified anti-settling agent, leveling agent and curing agent into a mixing tank, and stir at high speed of 2000 r / min for 20 min at room temperature to obtain a mixture. S4. Place the mixture on a horizontal grinding mill with a grinding flow rate of 100 L / h and circulate the grinding to a fineness of ≤15 μm to obtain a conductive primer for use on polycarbonate substrates.

[0028] Experimental Example 2: The primer and the coating film obtained by electrostatic spraying on the polycarbonate substrate were tested for cross-cut adhesion, water resistance, high-pressure water washing, gravel impact, dry film resistance and storage stability. The test results are shown in Table 2.

[0029] Table 2 Test results of primer and paint film in Example 2 As shown in Table 2, a modified anti-settling agent was used in this embodiment. It can be seen that the high-pressure water washing performance of the coating is improved. At the same time, after storage at 50 °C for 1 month, the fineness is still maintained below 15 μm, and the storage stability is also significantly improved. In addition, the adhesion, water resistance, crushed stone impact performance and dry film resistance performance also meet the requirements.

[0030] Example 3: A conductive primer for polycarbonate substrates is basically the same as in Example 1, except that the proportions of the components are different. The specific components by weight are as follows: The mixture contains 36 parts acrylic resin, 56 parts solvent, 3.4 parts dispersant, 3.4 parts conductive carbon black, 8.5 parts rutile titanium dioxide, 3.4 parts modified anti-settling agent, 0.3 parts leveling agent, and 5 parts curing agent.

[0031] The preparation method of the conductive primer applied to polycarbonate substrate described above is basically the same as that in Example 1, except that the proportions of each component in steps S1 and S2 are different. The specific steps are as follows: S1. Add tea polyphenols and auxiliary solvents into a stirred tank at a mass ratio of 84:16, and stir at low speed of 750 r / min for 20 min at room temperature to obtain tea polyphenol solution. S2. Heat the mixing vessel to 120 ℃ using an oil bath, add polyamide wax and tea polyphenol liquid into the mixing vessel at a mass ratio of 50:50, stir at a constant temperature and high speed of 2000 r / min for 20 min, and cool to room temperature to obtain the modified anti-settling agent. S3. Add acrylic resin, solvent, dispersant, conductive carbon black, rutile titanium dioxide, modified anti-settling agent, leveling agent and curing agent into a mixing tank, and stir at high speed of 2000 r / min for 20 min at room temperature to obtain a mixture. S4. Place the mixture on a horizontal grinding mill with a grinding flow rate of 100 L / h and circulate the grinding to a fineness of ≤15 μm to obtain a conductive primer for use on polycarbonate substrates.

[0032] Experimental Example 3: The primer and the coating film obtained by electrostatic spraying on the polycarbonate substrate were tested for cross-cut adhesion, water resistance, high-pressure water washing, gravel impact, dry film resistance and storage stability. The test results are shown in Table 3.

[0033] Table 3 Test results of primer and paint film in Example 3 As shown in Table 3, a modified anti-settling agent was used in this embodiment. It can be seen that the high-pressure water washing performance of the coating is improved. At the same time, after storage at 50 °C for 1 month, the fineness is still maintained below 15 μm, and the storage stability is also significantly improved. In addition, the adhesion, water resistance, crushed stone impact performance and dry film resistance performance also meet the requirements.

[0034] Example 4: A conductive primer for polycarbonate substrates is basically the same as in Example 1, except that the proportions of the components are different. The specific components by weight are as follows: The mixture consists of 40 parts acrylic resin, 60 parts solvent, 4 parts dispersant, 4 parts conductive carbon black, 8 parts rutile titanium dioxide, 4 parts modified anti-settling agent, 0.5 parts leveling agent, and 5 parts curing agent.

[0035] The preparation method of the conductive primer applied to polycarbonate substrate described above is basically the same as that in Example 1, except that the proportions of each component in steps S1 and S2 are different. The specific steps are as follows: S1. Add tea polyphenols and auxiliary solvents into a stirred tank at a mass ratio of 80:20, and stir at low speed of 750 r / min for 20 min at room temperature to obtain tea polyphenol solution. S2. Heat the mixing vessel to 120 ℃ using an oil bath, add polyamide wax and tea polyphenol liquid into the mixing vessel at a mass ratio of 55:45, stir at a constant temperature and high speed of 2000 r / min for 20 min, and cool to room temperature to obtain the modified anti-settling agent. S3. Add acrylic resin, solvent, dispersant, conductive carbon black, rutile titanium dioxide, modified anti-settling agent, leveling agent and curing agent into a mixing tank, and stir at high speed of 2000 r / min for 20 min at room temperature to obtain a mixture. S4. Place the mixture on a horizontal grinding mill with a grinding flow rate of 100 L / h and circulate the grinding to a fineness of ≤15 μm to obtain a conductive primer for use on polycarbonate substrates.

[0036] Experimental Example 4: The primer and the coating film obtained by electrostatic spraying on the polycarbonate substrate were tested for cross-cut adhesion, water resistance, high-pressure water washing, gravel impact, dry film resistance and storage stability. The test results are shown in Table 4.

[0037] Table 4 Test results of primer and paint film in Example 4 As shown in Table 4, a modified anti-settling agent was used in this embodiment. It can be seen that the high-pressure water washing performance of the coating is improved. At the same time, after storage at 50 °C for 1 month, the fineness is still maintained below 15 μm, and the storage stability is also significantly improved. In addition, the adhesion, water resistance, crushed stone impact performance and dry film resistance performance also meet the requirements.

[0038] Comparative example: A conductive primer for polycarbonate substrates is basically the same as in Example 4, except that an unmodified anti-settling agent is used instead of a modified anti-settling agent. The specific components by weight are as follows: The mixture contains 40 parts acrylic resin, 60 parts solvent, 4 parts dispersant, 4 parts conductive carbon black, 8 parts rutile titanium dioxide, 4 parts unmodified anti-settling agent, 0.5 parts leveling agent, and 5 parts curing agent.

[0039] The preparation method of the conductive primer applied to polycarbonate substrate described above is basically the same as that in Example 4, except that steps S1 and S2 are not required. The specific steps are as follows: S3. Add acrylic resin, solvent, dispersant, conductive carbon black, rutile titanium dioxide, unmodified anti-settling agent, leveling agent and curing agent into a mixing tank, and stir at high speed of 2000 r / min for 20 min at room temperature to obtain a mixture. S4. Place the mixture on a horizontal grinding mill with a grinding flow rate of 100 L / h and circulate the grinding to a fineness of ≤15 μm to obtain a conductive primer for use on polycarbonate substrates.

[0040] Experimental Example 5: The primer and the coating film obtained by electrostatic spraying on the polycarbonate substrate were tested for cross-cut adhesion, water resistance, high-pressure water washing, gravel impact, dry film resistance and storage stability. The test results are shown in Table 5.

[0041] Table 5 Test results of primer and paint film in the comparative example As shown in Table 5, comparing Example 4 and the comparative example, it can be seen that the modified anti-settling agent significantly improves the storage stability of the coating and enhances the high-pressure washing performance compared to the unmodified anti-settling agent by preventing carbon black flocculation.

[0042] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A conductive primer for use on polycarbonate substrates, characterized in that, The raw materials for this primer include the following components in parts by weight: The ingredients are: 30-40 parts acrylic resin, 50-60 parts solvent, 2-4 parts dispersant, 2-4 parts conductive carbon black, 8-10 parts rutile titanium dioxide, 2-4 parts modified anti-settling agent, 0.1-0.5 parts leveling agent, and 3-7 parts curing agent. The modified anti-settling agent is a polyamide modified with tea polyphenols.

2. The conductive primer for polycarbonate substrates according to claim 1, characterized in that, The acrylic resin is a hydroxy acrylic copolymer, wherein the solid content of the hydroxy acrylic copolymer is 40-60 wt%, the hydroxyl value is 10-30 mg KOH / g, and the glass transition temperature is 80-100 ℃.

3. The conductive primer for polycarbonate substrates according to claim 1, characterized in that, The solvent used is propylene glycol methyl ether.

4. The conductive primer for polycarbonate substrates according to claim 1, characterized in that, The dispersant is an acrylic block copolymer.

5. A conductive primer for polycarbonate substrates according to claim 1, characterized in that, The rutile titanium dioxide is rutile titanium dioxide produced by the sulfuric acid process after inorganic surface treatment with zirconium oxide and alumina.

6. The conductive primer for polycarbonate substrates according to claim 1, characterized in that, The modified anti-settling agent is a polyamide wax modified with tea polyphenol liquid, and the mass ratio of the polyamide wax to the tea polyphenol liquid is (45~55):(45~55).

7. A conductive primer for a polycarbonate substrate according to claim 6, characterized in that, The tea polyphenol solution includes tea polyphenols and a secondary solvent, wherein the secondary solvent is ethyl acetate, and the mass ratio of tea polyphenols to secondary solvent is (80~90):(10~20).

8. The conductive primer for polycarbonate substrates according to claim 1, characterized in that, The leveling agent is polyether-modified polydimethylsiloxane; The curing agent is hexamethylene diisocyanate.

9. A method for preparing a conductive primer for a polycarbonate substrate as described in any one of claims 1 to 8, characterized in that, The method includes the following steps: S1. Stir the tea polyphenols and auxiliary solvent at low speed to obtain a tea polyphenol solution; S2. Polyamide wax and tea polyphenol solution are stirred at high speed to obtain a modified anti-settling agent; S3. The acrylic resin, solvent, dispersant, conductive carbon black, rutile titanium dioxide, modified anti-settling agent, leveling agent and curing agent are stirred at high speed to obtain a mixture; S4. Grind the mixture to obtain a conductive primer for use on polycarbonate substrates.

10. A method for preparing a conductive primer applied to a polycarbonate substrate according to claim 9, characterized in that, In step S1, the temperature of low-speed stirring is 10~40 ℃, the speed is 500~1000 r / min, and the time is 10~30 min; In step S2, the high-speed stirring temperature is 110~130 ℃, the speed is 1500~2500 r / min, and the time is 10~30 min; In step S3, the high-speed stirring temperature is 10~40 ℃, the speed is 1500~2500 r / min, and the time is 10~30 min; In step S4, the grinding flow rate is 80~120 L / h, and the fineness of the primer is ≤20 μm.

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