A PVD indium plating photocuring primer, a preparation method and application thereof

Abstract

The application provides a photocuring primer for PVD indium plating, which comprises the following raw material components in parts by weight: 2-unsaturated polyurethane resin 30-45; acrylate monomer 5-15; functional thermoplastic resin 3-10; photoinitiator 1-5; auxiliary agent 0.05-0.5; and solvent 30-50, wherein the weight ratio of the functional thermoplastic resin to the 2-unsaturated polyurethane resin is 1:15 to 1:3, and the surface water contact angle of the paint film formed after curing of the photocuring primer is less than 95 degrees. The application also provides a preparation method and application of the photocuring primer for PVD indium plating.

Description

Technical Field

[0001] This invention relates to the field of automotive coating technology, and in particular to photocurable primers for PVD (vacuum evaporation) indium plating, their preparation methods and applications, and automotive decorative parts. Background Technology

[0002] Metallization surface treatment technology for plastic substrates has wide applications in the automotive parts industry, such as front grille trim, door trim, tailgate trim, and door handles. Traditional processes primarily use electroplating, but this generates large amounts of heavy metal wastewater, causing environmental pollution. Furthermore, with the development of autonomous driving technology and personalized demands in automobiles, new functional requirements are being placed on traditional decorative parts, such as millimeter-wave penetration (ACC function) and light transmittance. Traditional electroplating processes can no longer meet these new functional requirements. PVD, as an important alternative technology, has broad application prospects and value; therefore, developing high-performance PVD coatings that meet the needs of automotive applications (especially exterior parts) is of great significance for the future development and upgrading of the automotive industry.

[0003] Currently, PVD coatings often experience metal plating peeling during long-term use. This is mainly due to insufficient adhesion between the coating and the substrate or primer, i.e., insufficient coating uptake. Automotive PVD coatings, in particular, have high durability requirements, demanding even higher uptake performance from the primer. The application of PVD coatings in automotive trim parts is a relatively new field. To reduce the risk of metal plating peeling, there is a need for coating compositions with improved performance, especially in primer uptake. Summary of the Invention

[0004] To address the aforementioned technical problems, the present invention aims to provide a photocurable coating composition.

[0005] The photocurable primer of the present invention comprises the following raw material components by weight: 20~50% unsaturated polyurethane resin 5~20 acrylate monomers Functional thermoplastic resins 2~15 Photoinitiator 1~15 Additives 0.01~1 Solvent 30~60.

[0006] Optionally, the weight-average molecular weight of the unsaturated polyurethane resin is in the range of 2000-10000.

[0007] Unsaturated polyurethane provides excellent coating properties. Furthermore, by adjusting the ratio of rigid to flexible segments in the polyurethane structure, the flexibility of the primer can be well controlled.

[0008] Optionally, the average functionality of the acrylate monomer is 2 to 5, for example, 3 to 5. If the functionality is too high, the crosslinking density after curing will be too high, the internal stress of the paint film will be too large, and the resulting paint film will be hard, brittle and prone to cracking; if the functionality is too low, the crosslinking density after curing will be low, resulting in a decrease in the strength of the paint film and thus a decrease in the paint film's resistance (such as water resistance, moisture resistance, etc.).

[0009] Optionally, the acrylate monomer is two or more of pentaerythritol triacrylate (PETA), dipentaerythritol hexaacrylate (DPHA), trimethylolpropane triacrylate (TMPTA), 1,6-hexanediol diacrylate (HDDA), neopentyl glycol diacrylate (NPGDA), and hydroxyethyl methacrylate (HEMA).

[0010] Optionally, the functional thermoplastic resin is one or more of acrylic resin, epoxy resin, polyester resin, and chlorinated polyolefin resin.

[0011] Preferably, the content of the functional thermoplastic resin is 2% to 10%. Its main function is to control the crosslinking density by adding the functional thermoplastic resin, thereby improving the overall performance of the coating film.

[0012] Optionally, the additive is one or more of organosilicon, fluorinated acrylic acid, and acrylic acid.

[0013] The dosage of the additive is 0.01~0.5, preferably 0.01~0.2. More preferably, the surface water contact angle of the paint film formed after the UV-curing primer is controlled to be <95°. This type of additive affects the surface polarity of the paint film, thereby affecting the plating performance. When the content is too high, the surface polarity will decrease, and the plating performance will decrease.

[0014] Preferably, the additive is an acrylic-based additive, which has relatively high surface polarity, which is beneficial for the adhesion of the metal coating to the primer.

[0015] Optionally, the solvent includes, but is not limited to, two or more of ethyl acetate, butyl acetate, cyclohexanone, diacetone alcohol, butanol, and butanone.

[0016] Optionally, the UV-curable primer comprises the following raw material components in parts by weight: 2-functional unsaturated polyurethane resin 30~45 5-15% acrylate monomers Functional thermoplastic resins 3~10 Photoinitiator 1~5 Additives 0.05~0.5 Solvent 30~50.

[0017] The present invention also provides a method for preparing the aforementioned photocurable primer, comprising the following steps: The photoinitiator and auxiliaries are pre-dissolved in a partial solvent to form component I; Mix the resin and the remaining solvent thoroughly to form component II; Then, while stirring, add component I to component II and mix thoroughly.

[0018] This invention also provides the application of UV-cured primers on automotive exterior parts.

[0019] The present invention also provides an automotive trim part, the preparation method of which includes the following steps: The UV-curable primer according to the present invention is sprayed onto the substrate of the automotive trim parts and then UV-cured under ultraviolet light; After the photocurable primer is formed, indium is deposited using physical vapor deposition to form an indium plating layer. And then a topcoat is applied to the indium plating layer and cured.

[0020] Compared with the prior art, the present invention has at least the following technical effects: The UV-curable primer coating composition of this invention is applied in the field of vacuum evaporation. After UV curing, the primer coating exhibits excellent adhesion to various plastic substrates such as ABS, PC, and ABS / PC, demonstrating superior coating properties. Combined with environmentally friendly PVD technology and a high-performance PVD topcoat, the coating exhibits excellent adhesion, resistance to boiling water, moisture resistance (40℃ condensate for 240 hours), resistance to damp heat (50℃ & 95%RH, 500 hours), resistance to salt spray (CASS salt spray for 48 hours), and resistance to hydrolysis (90℃ & 96%RH, 72 hours). Detailed Implementation

[0021] The technical solution of the present invention will be further described below with reference to specific embodiments, but the present invention is not limited thereto. [Preparation of Examples]

[0022] According to the ingredient list in Table 1, the preparations of Examples 1-3 of the present invention were prepared.

[0023] Step 1: Mix and disperse photoinitiator 184, BYK-358, and ethyl acetate for 15 minutes to obtain component I; Step 2: Mix unsaturated polyurethane resin, pentaerythritol triacrylate, 1,6-hexanediol diacrylate, functional thermoplastic resin, butyl acetate, and diacetone alcohol evenly and disperse for 30 minutes to obtain component II. Step 3: Finally, add component I to component II and disperse for 60 minutes to ensure thorough mixing. The operating temperature is 20-50℃. [Preparation of the comparative example]

[0024] Comparative Examples 1-3 were prepared in the same manner according to the ingredient list in Table 1.

[0025] Table 1. Composition of Examples 1-3 and Comparative Examples 1-3 (by weight) Photoinitiator 184 4 4 4 4 4 4 BYK-358 0.2 0.2 0.2 0.2 0.2 0.2 2-functional unsaturated polyurethane resin 40 35 45 33 -- 40 6-functional unsaturated polyurethane resin -- -- -- -- 30 -- Pentaerythritol triacrylate 7 3 7 17 7 7 1,6-Hexanediol diacrylate 4 4 4 4 4 4 Functional thermoplastic resins 9 9 3 9 9 -- solvent 37.8 46.7 38.7 34.8 37.3 46.8 Among them, photoinitiator 184 was obtained from Taiwan, China; the solvent was a mixture of ethyl acetate, butyl acetate and diacetone alcohol. The UV coating solutions prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to performance testing. The testing process was as follows: primer was sprayed onto a PC substrate, UV cured; indium plating was evaporated; topcoat was sprayed, and UV cured; curing energy was 800-1500 mJ / cm. 2 Light intensity 60-150 wm / cm 2 .

[0026] [Testing Method] 1. Adhesion: The adhesion of all samples after the coating has been applied and cured was tested using the cross-cut adhesion test.

[0027] 2. Water boiling resistance: Immerse in a 90℃ water bath for 24 hours.

[0028] 3. Resistance to damp heat: After being placed in a constant temperature and humidity chamber at 50℃ and 95%RH for 500 hours, the adhesion was measured after removal.

[0029] 4. Hydrolysis: Place in a constant temperature and humidity chamber at 90℃ and 96%RH for 72 hours, then remove and measure the adhesion.

[0030] 5. Moisture resistance: After being placed in a condensation chamber at 40℃ and 100%RH for 240 hours, the adhesion is measured.

[0031] 6. Salt spray resistance: After the sample surface is scratched, it is placed in the CASS salt spray chamber for 48 hours. After removal, the adhesion is measured.

[0032] The performance test results are shown in Table 2 below.

[0033] Table 2. Performance of Examples 1-3 and Comparative Examples 1-3 Initial adhesion ASTM D3359-1997 5B 5B 5B 5B 0B 5B Resistant to boiling Boil in 90℃ water for 24 hours 5B 5B 5B 2-3B --- 4B Moist heat resistance 50℃ & 95%RH, 500h 5B 5B 5B 1-2B --- 3-4B hydrolysis 90℃ & 96%RH, 72h 5B 5B 5B 0B --- 0B Moisture resistant 40℃ condensate 240h 5B 5B 5B 2-3B --- 5B Salt spray resistance CASS*48h 5B 5B 5B 2-3B --- 5B The test results in Table 2 show that: According to Examples 1-3 of the present invention, the initial adhesion of the primer after curing is 5B, and the adhesion after boiling water, damp heat, hydrolysis, moisture resistance and salt spray resistance tests is also 5B. Therefore, the UV-curable primer coating of the present invention has excellent adhesion, boiling water resistance, moisture resistance (40℃ condensate water for 240h), damp heat resistance (50℃ & 95%RH, 500h), salt spray resistance (CASS salt spray for 48h), and hydrolysis resistance (90℃ & 96%RH, 72h) performance after curing.

[0034] Unlike the present invention, Comparative Example 2 did not add difunctional unsaturated polyurethane resin, but instead added hexafunctional unsaturated polyurethane resin. When the initial adhesion test was performed after curing, it was 0B, and the adhesion between the indium layer and the primer was destroyed.

[0035] Comparative Example 3 did not add any functional thermoplastic resin. After the paint film was cured, although the initial adhesion was 5B, the adhesion decreased after water boiling resistance, damp heat resistance, and hydrolysis tests. In fact, the adhesion in the hydrolysis test was 0B.

[0036] In Comparative Example 1, the amount of pentaerythritol triacrylate was large, which increased the crosslinking density of the coating. After the paint film was cured, although the initial adhesion was 5B, the adhesion decreased after water boiling resistance, damp heat resistance, hydrolysis test, moisture resistance and salt spray test. The adhesion in the hydrolysis test was even 0B.

[0037] The embodiments described above are merely examples of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention.

Claims

1. A PVD indium-plated UV-curable primer, characterized in that, By weight, it includes the following raw material components: 2-functional unsaturated polyurethane resin 30~45; 5-15% acrylate monomers; Functional thermoplastic resin 3~10; Photoinitiator 1~5; Additives: 0.05~0.5; Solvent 30~50, The weight ratio of the functional thermoplastic resin to the difunctional unsaturated polyurethane resin is between 1:15 and 1:

3. The surface water contact angle of the paint film formed after the UV-curing primer is <95°.

2. The PVD indium-plated photocurable primer according to claim 1, characterized in that, The weight-average molecular weight of the difunctional unsaturated polyurethane resin is in the range of 2000-10000.

3. The PVD indium-plated photocurable primer according to claim 1, characterized in that, The average functionality of the acrylate monomer is 3 to 5.

4. The PVD indium-plated photocurable primer according to claim 1, characterized in that, The additive is one or more of organosilicon, fluorinated acrylic acid, and acrylic acid.

5. The PVD indium-plated photocurable primer according to claim 1, characterized in that, The additive is acrylic acid BYK-358.

6. The PVD indium-plated photocurable primer according to claim 1, characterized in that, The dosage of the auxiliary agent is 0.01~0.

5.

7. A method for preparing the PVD indium-plated photocurable primer according to claim 1, characterized in that, Includes the following steps: The photoinitiator and auxiliaries are pre-dissolved in a partial solvent to form component I; The polyurethane resin, thermoplastic resin, acrylate monomer, and remaining solvent are mixed and stirred until homogeneous to form component II; Then, while stirring, add component I to component II and mix thoroughly.

8. The application of the PVD indium-plated UV-cured primer as described in claim 1 on automotive trim parts.

9. A car trim piece, characterized in that, The coating preparation method for the automotive trim parts includes the following steps: The PVD indium-plated UV-curable primer according to claims 1-8 is sprayed onto the substrate of automotive trim parts and then cured under ultraviolet light. After the photocurable primer is formed, indium is deposited using physical vapor deposition to form an indium plating layer. A topcoat is applied to the indium-plated layer.