Photochromic automobile coating and preparation method thereof

Abstract

The invention relates to a photochromic automobile coating and a preparation method thereof, and belongs to the technical field of coatings, the photochromic automobile coating comprises the following components by weight: 70-80 parts of chromotropic dye modified acrylic resin; 20-30 parts of a solvent; 0.2 to 0.5 part of a leveling agent; 1-2 parts of a drier; 0.6 to 1.2 parts of an anti-light aging agent; wherein the color-changing dye modified acrylic resin is resin liquid with the molecular weight of 5000 to 6000, the solid content of 68 to 72 percent and the hydroxyl value of 120 to 130, which is obtained by refluxing styrene, butyl methacrylate, hydroxypropyl acrylate, dibenzoyl peroxide, 2, 4-diphenyl-4-methyl-1-pentene and silicon modified naphthopyran according to the mass ratio of (30 to 35) to (4 to 6) to (15 to 18) to (2 to 3) to (0.8 to 1) to (0.2 to 0.4) at 140 DEG C. Compared with the prior art, the photochromic coating provided by the invention solves the problem of slow color change and color fading of an acrylic coating under high film thickness, and a paint film prepared from the prepared coating has better gloss and higher distinctness of image.

Description

Technical Field

[0001] The invention relates to the technical field of coatings, and in particular to a photochromic automobile coating and a preparation method thereof. Background Art

[0002] In the current automotive coatings field, acrylic coating systems occupy a dominant position. High-temperature thermosetting acrylic coatings are mostly used for car bodies, while low-temperature hydroxyl acrylic coatings are widely used for automotive interior and exterior trims. As consumers' requirements for car appearance continue to increase, the novelty and beauty of colors have become one of the key considerations for automakers.

[0003] The application of photochromic principle provides a new direction for the innovation of automotive coatings. Incorporating photochromic effect into acrylic resin system is expected to make automotive coatings show unique visual effects and meet consumers' pursuit of personalization and beauty.

[0004] However, automotive coatings have strict requirements on coating thickness. A higher film thickness not only presents a smooth and plump dry film appearance, but also gives the coating better light aging resistance, chemical resistance and physical resistance. Taking the clearcoat layer of automotive interior and exterior coatings as an example, the recommended film thickness is between 25-60 microns. At the same time, automotive coatings must have extremely high light aging resistance, which is equivalent to the performance standard of a car exposed to the sun in Florida for about 200 consecutive days.

[0005] In the case of such thick coating and high light aging resistance requirements, if photochromic dyes are directly added, two key problems will arise. First, the coating changes color and fades slowly, and cannot respond to light changes in time; second, the gloss and vividness of the paint film are poor, which seriously affects the appearance and texture of the car. The main reasons are the poor compatibility of the dye with acrylic resin, and the influence of the coating thickness and anti-light aging additives on the dye, which leads to poor photosensitivity.

[0006] Therefore, developing a technology that can solve the above problems and effectively integrate the photochromic effect into the acrylic coating system is of great significance to the development of the automotive coatings industry. Summary of the invention

[0007] The purpose of the present invention is to provide a photochromic automotive coating and a preparation method thereof in order to overcome at least one of the defects of the above-mentioned prior art. The present invention utilizes the silanoloxy group of a silane coupling agent to modify naphthopyran, and obtains modified naphthopyran under the catalysis of p-toluenesulfonic acid. The silanoloxy group as a skeleton structure reacts with naphthopyran and participates in the reaction with acrylic acid monomer, thereby ensuring compatibility and temperature resistance.

[0008] The purpose of the present invention can be achieved by the following technical solutions:

[0009] One of the objects of the present invention is a photochromic automotive coating comprising the following components in parts by weight:

[0010]

[0011] The acrylic resin modified by the color-changing dye is styrene, butyl methacrylate, hydroxypropyl acrylate, dibenzoyl peroxide (BPO), 2,4-diphenyl-4-methyl-1-pentene (AMSD) and silicon-modified naphthopyran in a mass ratio of (30-35): (4-6): (15-18): (2-3): (0.8-1): (0.2-0.4) and refluxed at 140°C to obtain a resin liquid with a molecular weight between 5000 and 6000, a solid content of 68-72%, and a hydroxyl value between 120 and 130. Styrene monomer can improve hardness and chemical resistance, butyl methacrylate adjusts the toughness of the resin because automotive coatings require a certain degree of flexibility, and hydroxypropyl acrylate provides hydroxyl value, which can react with HDI isocyanate to form a film by cross-linking.

[0012] Further, the silicon-modified naphthopyran is naphthopyran and a silane coupling agent (Y-glycidyloxypropyltrimethylsilane KH560) in a mass ratio of 1:(1-2), in N-methylpyrrolidone with p-toluenesulfonic acid as a catalyst, at 100-120° C., refluxed for 2-3 hours to obtain the silicon-modified naphthopyran;

[0013] Furthermore, the solvent is a mixture of xylene and butyl acetate in a mass ratio of 1:(1-2).

[0014] Furthermore, the leveling agent is polydimethylsiloxane. The silicon-oxygen bond increases the wetting and leveling properties of the coating to the lower coating. The leveling agent is commercially available BYK333.

[0015] Furthermore, the drying agent is a mixture of dibutyltin dilaurate and butyl acetate in a mass ratio of 1:(99-102).

[0016] Furthermore, the anti-light aging agent is a mixture of an ultraviolet absorber and a hindered amine stabilizer in a mass ratio of (1-3):1.

[0017] Furthermore, the ultraviolet absorber is 384-2; the hindered amine stabilizer is 123.

[0018] The second object of the present invention is to provide a method for preparing the photochromic automotive coating as described above, comprising the following steps:

[0019] The acrylic resin modified by the color-changing dye, the solvent, the leveling agent, the drying agent and the anti-light aging agent are uniformly stirred to obtain the photochromic automobile coating.

[0020] Furthermore, the stirring speed is 1000-1200 rpm.

[0021] Compared with the prior art, the present invention has the following beneficial effects.

[0022] (1) The present invention provides a photochromic automotive coating that can be used to produce a coating with a film thickness of 25-60 microns and maintain a relatively fast color change and fading effect;

[0023] (2) The present invention provides a photochromic automotive coating, wherein the modified color-changing dye does not reduce the gloss of the varnish or the distinctness of image;

[0024] (3) The present invention provides a photochromic automotive coating, wherein the chemical resistance and physical resistance of the resulting coating are not affected. DETAILED DESCRIPTION

[0025] The following is a detailed description of an embodiment of the present invention. This embodiment is implemented on the premise of the technical solution of the present invention, and a detailed implementation method and a specific operation process are given, but the protection scope of the present invention is not limited to the following embodiment.

[0026] The present invention provides a photochromic automotive coating, comprising the following components in parts by weight:

[0027]

[0028] The acrylic resin modified by the color-changing dye is styrene, butyl methacrylate, hydroxypropyl acrylate, dibenzoyl peroxide (BPO), 2,4-diphenyl-4-methyl-1-pentene (AMSD) and silicon-modified naphthopyran in a mass ratio of (30-35): (4-6): (15-18): (2-3): (0.8-1): (0.2-0.4) and refluxed at 140°C to obtain a resin liquid with a molecular weight between 5000 and 6000, a solid content of 68-72%, and a hydroxyl value between 120 and 130. Styrene monomer can improve hardness and chemical resistance, butyl methacrylate adjusts the toughness of the resin because automotive coatings require a certain degree of flexibility, and hydroxypropyl acrylate provides hydroxyl value, which can react with HDI isocyanate to form a film by cross-linking.

[0029] In some embodiments of the present invention, the silicon-modified naphthopyran is naphthopyran and a silane coupling agent (Y-glycidyloxypropyltrimethylsilane KH560) in a mass ratio of 1:(1-2), in N-methylpyrrolidone (NMP) with p-toluenesulfonic acid as a catalyst, at 100-120° C., refluxed for 2-3 hours to obtain the silicon-modified naphthopyran;

[0030] In some embodiments of the present invention, the solvent is a mixture of xylene and butyl acetate in a mass ratio of 1:(1-2).

[0031] In some embodiments of the present invention, the leveling agent is polydimethylsiloxane. The silicon-oxygen bond increases the wetting and leveling properties of the coating to the lower coating. The leveling agent is commercially available BYK333.

[0032] In some embodiments of the present invention, the drying agent is a mixture of dibutyltin dilaurate and butyl acetate in a mass ratio of 1:(99-102).

[0033] In some embodiments of the present invention, the anti-light aging agent is a mixture of an ultraviolet absorber and a hindered amine stabilizer in a mass ratio of (1-3):1.

[0034] In some embodiments of the present invention, the ultraviolet absorber is 384-2.

[0035] In some embodiments of the present invention, the hindered amine stabilizer is 123.

[0036] The present invention also provides a method for preparing a photochromic automobile coating, comprising the following steps:

[0037] (1) The reaction kettle is passed through nitrogen to replace the air, 200 parts of NMP solvent, 20 parts of naphthopyran, 20 parts of silane coupling agent (Y-glycidyloxypropyltrimethylsilane KH560), and 10 parts of p-toluenesulfonic acid are slowly added dropwise, and the addition is completed within 30 minutes. The mixture is refluxed for 2-3 hours at 100-120° C. under stirring to obtain silicon-modified naphthopyran;

[0038] (2) The reactor was filled with nitrogen to replace the air, and 30-35 parts of styrene, 4-6 parts of butyl methacrylate, and 15-18 parts of hydroxypropyl acrylate were added in sequence according to the mass ratio. Under the conditions of 10 parts of xylene and 10 parts of tert-butyl perbenzoate (PMA), 2-3 parts of BPO and 0.8-1 parts of AMSD were added dropwise within 1 hour under stirring at 140° C. After the addition was completed, the temperature was lowered to 100° C., and 0.2-0.4 parts of a solution of silicon-modified naphthopyran was added dropwise. The mixture was refluxed for 30 minutes to obtain a hydroxy acrylic resin having a molecular weight of 5000-6000, a solid content of 68-72%, and a hydroxyl value of 120-130.

[0039] (3) Weigh 70 to 80 parts of the silicon-modified naphthopyran hydroxy acrylic resin obtained in step (2) and add it into a container. Under stirring at room temperature, add 20 to 30 parts of a mixed solvent of xylene / butyl acetate (mass ratio 1 / 1), 0.2 to 0.5 parts of a leveling agent, 1 to 2 parts of a drying agent (1% dibutyltin dilaurate), and 0.6 to 1.2 parts of an anti-light aging agent in sequence. Stir for 2 to 5 minutes to obtain a varnish.

[0040] (4) The varnish obtained in step (3) and the curing agent 3390 are mixed in a mass ratio of 100:30, and 20 parts of xylene and 20 parts of butyl acetate are added. After stirring for 2 to 5 minutes, the mixture is sprayed on the surface of the color paint using compressed air and a spray gun, and baked at 70 to 80° C. for 60 minutes to obtain a varnish with a dry film thickness of 25 to 60 μm.

[0041] The mixing process is as follows:

[0042] Step (1) stirring speed 200-400 rpm;

[0043] Step (2) stirring speed 500-800 rpm;

[0044] Step (3) stirring speed 1000-1200 rpm;

[0045] Step (4) stirring speed 1000-1200 rpm.

[0046] Example 1

[0047] This embodiment provides a photochromic automotive coating, and the input weight parts are as follows:

[0048]

[0049] The preparation method of the coating adopts the following steps:

[0050] (1) The reaction kettle is passed through nitrogen to replace the air, 200 parts of NMP solvent, 20 parts of naphthopyran, 20 parts of silane coupling agent, and 10 parts of p-toluenesulfonic acid are slowly added dropwise, and the addition is completed within 30 minutes. The reaction mixture is refluxed for 2 to 3 hours at 100 to 120° C. under stirring to obtain silicon-modified naphthopyran;

[0051] (2) The reactor was filled with nitrogen to replace the air, and 30 parts of styrene, 4 parts of butyl methacrylate, and 15 parts of hydroxypropyl acrylate were added in sequence according to the mass ratio. Under the conditions of 10 parts of xylene and 10 parts of PMA, 2 parts of BPO and 0.8 parts of AMSD were added dropwise within 1 hour under stirring at 140° C. After the addition was completed, the temperature was lowered to 100° C., and 0.2 parts of a solution of silicon-modified naphthopyran was added dropwise. The mixture was refluxed for 30 minutes to obtain a hydroxy acrylic resin having a molecular weight of 5000-6000, a solid content of 68-72%, and a hydroxyl value of 120-130.

[0052] (3) Weigh 70 parts of the silicon-modified naphthopyran hydroxy acrylic resin obtained in step (2) and add it into a container. Under stirring at room temperature, add 28.2 parts of a mixed solvent of xylene / butyl acetate (mass ratio 1 / 1), 0.2 parts of a leveling agent, 1 part of a drying agent (1% dibutyltin dilaurate), and 0.6 parts of an anti-light aging agent in sequence, and stir for 2 to 5 minutes to obtain a varnish.

[0053] (4) The varnish obtained in step (3) and the curing agent 3390 are mixed in a mass ratio of 100:30, and 20 parts of xylene and 20 parts of butyl acetate are added. After stirring for 2 to 5 minutes, the mixture is sprayed on the surface of the color paint using compressed air and a spray gun, and baked at 70 to 80° C. for 60 minutes to obtain a varnish with a dry film thickness of 25 μm.

[0054] The paint film prepared in this embodiment was tested for relevant properties, and the results are shown in the following table:

[0055]

[0056] Example 2

[0057] This embodiment provides a photochromic automotive coating, and the input weight parts are as follows:

[0058]

[0059]

[0060] The preparation method of the coating adopts the following steps:

[0061] (1) The reaction kettle is passed through nitrogen to replace the air, 200 parts of NMP solvent, 20 parts of naphthopyran, 20 parts of silane coupling agent, and 10 parts of p-toluenesulfonic acid are slowly added dropwise, and the addition is completed within 30 minutes. The reaction mixture is refluxed for 2 to 3 hours at 100 to 120° C. under stirring to obtain silicon-modified naphthopyran;

[0062] (2) The reactor was filled with nitrogen to replace the air, and 33 parts of styrene, 4 parts of butyl methacrylate, and 16 parts of hydroxypropyl acrylate were added in sequence according to the mass ratio. Under the conditions of 10 parts of xylene and 10 parts of PMA, 2.5 parts of BPO and 0.9 parts of AMSD were added dropwise within 1 hour under stirring at 140° C. After the addition was completed, the temperature was lowered to 100° C., and 0.3 parts of a solution of silicon-modified naphthopyran was added dropwise. The mixture was refluxed for 30 minutes to obtain a hydroxy acrylic resin having a molecular weight of 5000-6000, a solid content of 68-72%, and a hydroxyl value of 120-130.

[0063] (3) Weigh 75 parts of the silicon-modified naphthopyran hydroxy acrylic resin obtained in step (2) and add it into a container. Under stirring at room temperature, add 22.3 parts of a mixed solvent of xylene / butyl acetate (mass ratio 1 / 1), 0.3 parts of a leveling agent, 1.5 parts of a drying agent (1% dibutyltin dilaurate), and 1 part of an anti-light aging agent in sequence, and stir for 2 to 5 minutes to obtain a varnish.

[0064] (4) The varnish obtained in step (3) and the curing agent 3390 are mixed in a mass ratio of 100:35, and 25 parts of xylene and 25 parts of butyl acetate are added. After stirring for 2 to 5 minutes, the mixture is sprayed on the surface of the color paint using compressed air and a spray gun, and baked at 70 to 80° C. for 60 minutes to obtain a varnish with a dry film thickness of 40 μm.

[0065] The paint film prepared in this embodiment was tested for relevant properties, and the results are shown in the following table:

[0066]

[0067]

[0068] Example 3

[0069] A photochromic automotive coating, the input weight parts are as follows:

[0070]

[0071] The preparation method of the coating adopts the following steps:

[0072] (1) The reaction kettle is passed through nitrogen to replace the air, 200 parts of NMP solvent, 20 parts of naphthopyran, 20 parts of silane coupling agent, and 10 parts of p-toluenesulfonic acid are slowly added dropwise, and the addition is completed within 30 minutes. The reaction mixture is refluxed for 2 to 3 hours at 100 to 120° C. under stirring to obtain silicon-modified naphthopyran;

[0073] (2) The reactor was filled with nitrogen to replace the air, and 35 parts of styrene, 6 parts of butyl methacrylate, and 18 parts of hydroxypropyl acrylate were added in sequence according to the mass ratio. Under the conditions of 10 parts of xylene and 10 parts of PMA, 3 parts of BPO and 1 part of AMSD were added dropwise within 1 hour under stirring at 140° C. After the addition was completed, the temperature was lowered to 100° C., and 0.4 parts of a solution of silicon-modified naphthopyran was added dropwise. The mixture was refluxed for 30 minutes to obtain a hydroxy acrylic resin having a molecular weight of 5000-6000, a solid content of 68-72%, and a hydroxyl value of 120-130.

[0074] (3) Weigh 80 parts of the silicon-modified naphthopyran hydroxy acrylic resin obtained in step (2) into a container, and add 16.3 parts of a mixed solvent of xylene / butyl acetate (mass ratio 1 / 1), 0.5 parts of a leveling agent, 2 parts of a drying agent (1% dibutyltin dilaurate), and 1.2 parts of an anti-light aging agent in sequence under stirring at room temperature, and stir for 2 to 5 minutes to obtain a varnish.

[0075] (4) The varnish obtained in step (3) and the curing agent 3390 are mixed in a mass ratio of 100:40, and 30 parts of xylene and 30 parts of butyl acetate are added. After stirring for 2 to 5 minutes, the mixture is sprayed on the surface of the color paint using compressed air and a spray gun, and baked at 70 to 80° C. for 60 minutes to obtain a varnish with a dry film thickness of 60 μm.

[0076] The paint film prepared in this embodiment was tested for relevant properties, and the results are shown in the following table:

[0077]

[0078] The above is only a preferred embodiment of the present invention, and does not limit the present invention in other forms. Any technician familiar with the profession may use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention still belongs to the protection scope of the technical solution of the present invention.

Claims

1. A photochromic automotive coating, characterized in that: The composition comprises the following components in parts by weight: 70-80 parts of acrylic resin modified with color-changing dye; 20-30 parts of solvent; 0.2-0.5 parts of leveling agent; 1-2 parts of drying agent; 0.6-1.2 parts of anti-light aging agent; Among them, the acrylic resin modified by the color-changing dye is styrene, butyl methacrylate, hydroxypropyl acrylate, dibenzoyl peroxide, 2,4-diphenyl-4-methyl-1-pentene and silicon-modified naphthopyran in a mass ratio of (30-35):(4-6):(15-18):(2-3):(0.8-1):(0.2-0.4) and is refluxed at 140°C to obtain a resin liquid with a molecular weight between 5000 and 6000, a solid content between 68 and 72%, and a hydroxyl value between 120 and 130.

2. A photochromic automotive coating according to claim 1, characterized in that: The silicon-modified naphthopyran is prepared by mixing naphthopyran and a silane coupling agent in a mass ratio of 1:(1-2) and refluxing for 2 to 3 hours at 100 to 120° C. in N-methylpyrrolidone with p-toluenesulfonic acid as a catalyst to obtain the silicon-modified naphthopyran.

3. The photochromic automotive coating according to claim 1, characterized in that: The solvent is a mixture of xylene and butyl acetate in a mass ratio of 1:(1-2).

4. The photochromic automotive coating according to claim 1, characterized in that: The leveling agent is polydimethylsiloxane.

5. The photochromic automotive coating according to claim 1, characterized in that: The drying agent is a mixture of dibutyltin dilaurate and butyl acetate in a mass ratio of 1:(99-102).

6. The photochromic automotive coating according to claim 1, characterized in that: The anti-light aging agent is a mixture of an ultraviolet absorber and a hindered amine stabilizer in a mass ratio of (1-3):

1.

7. A photochromic automotive coating according to claim 6, characterized in that: The ultraviolet absorber is 384-2.

8. The photochromic automotive coating according to claim 6, characterized in that: The hindered amine stabilizer is 123.

9. A method for preparing a photochromic automotive coating according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: uniformly stirring acrylic resin modified by a color-changing dye, a solvent, a leveling agent, a drying agent and an anti-light aging agent to obtain a photochromic automobile coating.

10. The method for preparing a photochromic automotive coating according to claim 9, characterized in that: The stirring speed is 1000-1200 rpm.

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