UV matt finish paint for aluminum substrate and preparation process of UV matt finish paint

Abstract

The invention discloses an aluminum substrate UV matt finish paint and a preparation process thereof, and relates to the technical field of paints.The aluminum substrate UV matt finish paint is prepared from, by mass, 10%-20% of modified polyurethane acrylate, 25%-32% of high-functionality aliphatic polyurethane acrylate, 18%-30% of special modified epoxy acrylate resin, 0.5%-2% of dispersing agent, 0.1%-0.5% of defoaming agent, 1%-3% of anti-settling powder and the balance water. The paint is prepared from the following components in percentage by weight: 10 to 15 percent of magnesium silicate mineral, 1 to 10 percent of matting powder, 0.2 to 1 percent of 1-hydroxycyclohexyl phenyl ketone, 0.5 to 3 percent of trimethylbenzoyl-diphenyl phosphine oxide, 1 to 3 percent of acrylate flatting agent, 0.2 to 1.2 percent of polyurea modified polyurethane rheological agent and 5 to 15 percent of trimethylolpropane triacrylate. According to the UV matte finishing paint disclosed by the invention, through compounding of ternary resin and enhancement of nano silicon dioxide, a rigid and tough cross-linked network is constructed, a paint film is free of cracks when being bent at 180 degrees, the adhesive force reaches grade 0, and a coating is resistant to acid and alkali etching liquid and free of corrosion by cooperating with a silane coupling agent and a light stabilization system, and the color difference is delta Elt after the UV matte finishing paint is subjected to high temperature of 260 DEG C; and 1.5, the anti-yellowing performance is excellent.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of coatings, in particular to an aluminum substrate UV matte finish and a preparation process thereof. BACKGROUND

[0002] Aluminum circuit board is widely used in the field of LED lighting, power module and other electronic fields due to its excellent heat conductivity, mechanical strength and lightweight characteristics. In order to ensure its reliability, a protective coating needs to be applied to the surface of the aluminum circuit board. At present, there are two mainstream methods in the industry: concentrated sulfuric acid anodizing method and environmentally friendly UV coating method. However, these two methods cannot meet the stringent requirements of high-end electronic products due to obvious defects. The specific defects of these two methods are as follows: Concentrated sulfuric acid anodizing method: a large amount of acid-containing wastewater is generated during production, causing serious environmental pollution, and the oxide layer formed is brittle and not resistant to scratching, which is easy to produce micro-cracks during subsequent mechanical processing, affecting the protection performance.

[0003] UV coating method: although it is more environmentally friendly, its performance still has bottlenecks, which are as follows: (1) Insufficient flexibility and adhesion of the paint film, easy to fall off when bending: the root cause lies in the fact that the conventional UV resin cross-linking network is too tight and too rigid, and the interfacial adhesion between the paint film and the aluminum substrate is not strong. When the aluminum substrate is bent or cut, the paint film cannot effectively release stress, leading to brittle fracture and peeling from the substrate, resulting in powder falling phenomenon; Poor chemical corrosion resistance, especially not resistant to acid and alkali etching solution: ordinary resin system is unstable under acidic conditions and is easily corroded to form visible "black spots"; in alkaline etching solution, ester bonds in the paint film are easily hydrolyzed, leading to swelling, whitening or even peeling of the paint film, which cannot protect the circuit; Poor heat resistance and anti-yellowing property: if traditional UV coatings contain aromatic ring structures or unstable photoinitiator residues, they are easily oxidized and molecular structure changes during subsequent SMT welding, high temperature compression and other processes above 220℃, leading to serious yellowing of the coating, affecting the appearance and performance of the product.

[0004] Therefore, there is an urgent need in the market for an aluminum substrate protective coating that combines environmental advantages and excellent comprehensive performance, which can remain stable under harsh mechanical processing, chemical environment and high temperature processing. SUMMARY

[0005] The application aims to provide an aluminum substrate UV matte finish paint and a preparation process thereof, which can solve the above problems.

[0006] To achieve the above-mentioned purpose, the application realizes the technical scheme as follows. An aluminum substrate UV matte finish paint comprises the following components in percentage by mass: Modified polyurethane acrylate: 10-20%; High-functionality aliphatic polyurethane acrylate: 25-32%; Special modified epoxy acrylate resin: 18-30%; Dispersing agent: 0.5-2%; Defoaming agent: 0.1-0.5%; Anti-settling powder: 1-3%; Magnesium silicate mineral: 10-15%; Matting powder: 1-10%; 1-hydroxycyclohexyl phenyl ketone: 0.2-1%; Trimethylbenzoyl-diphenyl phosphine oxide: 0.5-3%; Acrylate leveling agent: 1-3%; Polyurea modified polyurethane rheological aid: 0.2-1.2%; Trimethylolpropane triacrylate: 5-15%.

[0007] Preferably, the application further comprises the following components in percentage by mass: Gamma-aminopropyl triethoxysilane coupling agent: 0.8-2%; 2-hydroxy-4-methoxybenzophenone: 0.1-0.4%; Tetrakis [beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid] pentaerythritol ester: 0.1-0.3%; The anti-settling powder is nano-silica with a silane-modified surface and a particle size of 50-100 nm.

[0008] Preferably, the application comprises the following components in percentage by mass: Modified polyurethane acrylate: 10-15%; High-functionality aliphatic polyurethane acrylate: 27-32%; Special modified epoxy acrylate resin: 18-25%; Dispersing agent: 1-2%; Defoamer: 0.1-0.5%; Nano-silica: 1.5-3%; Magnesium silicate mineral: 10-15%; Matting powder: 4-10%; 1-hydroxycyclohexyl phenyl ketone: 0.2-1%; Trimethylbenzoyl-diphenyl phosphine oxide: 0.5-3%; Acrylate leveling agent: 1-3%; Polyurea modified polyurethane rheological aid: 0.2-0.5%; Trimethylolpropane triacrylate: 5-10%; Gamma-aminopropyl triethoxysilane coupling agent: 0.8-2%; 2-hydroxy-4-methoxy benzophenone: 0.1-0.4%; Tetrakis [beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid] pentaerythritol ester: 0.1-0.3%.

[0009] Preferably, by mass percentage, the following components are included: Modified polyurethane acrylate: 13-18%; High functionality aliphatic polyurethane acrylate: 25-30%; Special modified epoxy acrylate resin: 25-30%; Dispersing agent: 0.8-1.3%; Defoamer: 0.1-0.5%; Nano-silica: 1-1.6%; Magnesium silicate mineral: 10-15%; Matting powder: 1-5%; 1-hydroxycyclohexyl phenyl ketone: 0.2-1%; Trimethylbenzoyl-diphenyl phosphine oxide: 0.5-3%; Acrylate leveling agent: 1-3%; Polyurea modified polyurethane rheological aid: 0.2-0.5%; Trimethylolpropane triacrylate: 8-15%; Gamma-aminopropyl triethoxysilane coupling agent: 0.8-2%; 2-hydroxy-4-methoxy benzophenone: 0.1-0.4%; Tetrakis [beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid] pentaerythritol ester: 0.1-0.3%.

[0010] Preferably, the modified polyurethane acrylate adopts Lankro L-8400C; the high-functionality aliphatic polyurethane acrylate adopts Ewonik BW8292; and the special modified epoxy acrylate resin adopts Lankro L-6118.

[0011] Preferably, the nano-silica adopts UG-S03D of Optimax; and the matting powder adopts Graces RAD-2105.

[0012] Preferably, the 1-hydroxycyclohexyl phenyl ketone adopts Tianjin Jiuri 184; and the trimethylbenzoyl-diphenyl phosphine oxide adopts Tianjin Jiuri TPO.

[0013] Preferably, the magnesium silicate mineral adopts Guangdong Housheng 6000-mesh talc powder; the dispersing agent adopts BYK-20084; the defoaming agent adopts TEGO920; the acrylate leveling agent adopts BYK-358N; and the trimethylolpropane triacrylate adopts Longrunfa YTM6350 of Ruyi.

[0014] A preparation process of an aluminum substrate UV matte finish paint, applied to the aluminum substrate UV matte finish paint, comprises the following steps: S1. Selecting a suitable production cylinder according to the batch, confirming that the inner wall of the cylinder has been cleaned, and confirming that the discharge valve is in a closed state; S2. First, 1 / 2 of the trimethylolpropane triacrylate and all of the dispersing agent are put in, and medium-speed dispersion of 1000±200 rpm is performed, and then the nano-silica is slowly and uniformly added; after the addition is completed, high-speed dispersion of 1500±200 rpm is switched to, and continuous dispersion is performed for 20-25 min, until the fineness of the slurry is ≤15 μm, to obtain a uniform translucent nano-pre-dispersed slurry; S3. In the nano-slurry prepared in the previous step, all of the modified polyurethane acrylate, the high-functionality aliphatic polyurethane acrylate, and the special modified epoxy acrylate resin are sequentially put in, medium-speed dispersion of 1000±200 rpm is adopted, continuous dispersion is performed for 15-20 min, the resin and the nano-slurry are fully fused, and whether the solution is uniform is observed; S4. After the dispersion in the previous step is completed, all of the magnesium silicate mineral and the matting powder are continuously added, the cooling water system is started, the temperature of the cylinder body is controlled to be not more than 40℃, and then high-speed dispersion of 1500±200 rpm is performed, and continuous dispersion is performed for 30-35 min; after the dispersion is completed, the fineness is detected to be ≤25 μm; S5, the rotating speed is reduced to medium speed of 1000±200 rpm, all defoaming agent, acrylate leveling agent and polyurea modified polyurethane rheological additive are sequentially added, and the dispersion is kept at the medium speed for 10-15 min until the rheological additive is completely swelled, and the system presents a uniform thixotropic state; S6, dispersion is carried out at low speed of 500±100 rpm, the remaining trimethylolpropane triacrylate is added for adjusting the final viscosity; subsequently, all γ-aminopropyl triethoxysilane coupling agent, 2-hydroxy-4-methoxybenzophenone and pentaerythritol tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] are sequentially added, and the dispersion is kept at the low speed of 500±100 rpm for 10 min to ensure uniform mixing; S7, the dispersion is kept at the low speed of 500±100 rpm, 1-hydroxycyclohexyl phenyl ketone and trimethylbenzoyl-diphenyl phosphine oxide are added, and the dispersion is kept for 5-10 min to ensure complete dissolution and uniform mixing.

[0015] The aluminum substrate UV matte finish paint and the preparation process thereof have the following beneficial effects: The aluminum substrate UV matte finish paint provided by the modified polyurethane acrylate, the high-functionality aliphatic polyurethane acrylate and the special modified epoxy acrylate are combined to form a resin system with excellent hydrolysis resistance and corrosion resistance, and the resin system forms a dense composite network with nano-silicon dioxide, and the sealing effect of the silane coupling agent on the interface forms a physical barrier, which can effectively block the penetration and corrosion of acid and alkali media, so that the paint film has no black spots, no bubbles and no peeling after being soaked in hydrochloric acid solution with pH=2 and sodium hydroxide solution with pH=9 for 24 hours, and the chemical resistance is far superior to that of conventional products. The aluminum substrate UV matte finish paint, the resin system formed by the combination of the modified polyurethane acrylate, the high-functionality aliphatic polyurethane acrylate and the special modified epoxy acrylate has excellent hydrolysis resistance and corrosion resistance, and forms a dense composite network with nano-silicon dioxide, and the sealing effect of the silane coupling agent on the interface forms a physical barrier, which can effectively block the penetration and corrosion of acid and alkali media, so that the paint film has no black spots, no bubbles and no peeling after being soaked in hydrochloric acid solution with pH=2 and sodium hydroxide solution with pH=9 for 24 hours, and the chemical resistance is far superior to that of conventional products. The resin system formed by the selected modified polyurethane acrylate, high-functionality aliphatic polyurethane acrylate and special modified epoxy acrylate is a completely aliphatic resin system, which can fundamentally avoid the production of chromophoric groups under high temperature due to aromatic ring structure; the complex photoinitiator TPO and 184 have low residual and are not prone to color generation, and 2-hydroxy-4-methoxybenzophenone and tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid] pentaerythritol ester constitute a high-efficiency light-heat stabilizing system, which synergistically inhibits the yellowing process, so that the color difference ΔE of the coating is less than 1.5 after extreme high-temperature tests of 220 DEG C / 1 hour and 260 DEG C / 2 hours, and the yellowing is almost imperceptible. The aluminum substrate UV matte finish paint of the present application uses nanometer silicon dioxide modified by silane as anti-settling powder, which not only prevents the settling of fillers, but also plays a role of "pinning" in the curing network due to the nanometer particles, thereby significantly improving the wear resistance and hardness of the paint film while retaining the flexibility thereof. The aluminum substrate UV matte finish paint of the present application combines the polyurea modified polyurethane rheological additive with nanometer silicon dioxide and matting powder, so that the coating has excellent thixotropy and anti-sagging property, and a uniform and flawless fine matte effect can be obtained on the surface even when a relatively thick film layer is applied, while ensuring no hard sedimentation during storage. The preparation process of the aluminum substrate UV matte finish paint of the present application adopts a pre-prepared nanometer slurry process, which ensures that the nanometer silicon dioxide is uniformly dispersed in the system in the form of completely de-agglomerated primary particles, so that the reinforcing effect is optimal; and the process of adding photoinitiators and functional additives afterwards avoids their thermal degradation and early reaction during high-speed dispersion, thereby ensuring the storage stability and final curing efficiency of the product. DETAILED DESCRIPTION

[0016] In order to enable those skilled in the art to better understand the technical solutions of the present application, the product of the present application is further described in detail below in combination with embodiments.

[0017] It should be noted that all the technical and scientific terms used herein have the same meanings as those commonly understood by the skilled in the art to which the present application belongs. The terms used in the specification of the present application are only for the purpose of describing the specific embodiments and are not intended to limit the present application. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0018] An aluminum substrate UV matte finish paint, comprising the following components in percentage by mass: Modified polyurethane acrylate: 10-20%; High-functionality aliphatic polyurethane acrylate: 25-32%; Special modified epoxy acrylate resin: 18-30%; Dispersant: 0.5-2%; Defoaming agent: 0.1-0.5%; Anti-settling powder: 1-3%; Magnesium silicate mineral: 10-15%; Matting powder: 1-10%; 1-hydroxycyclohexyl phenyl ketone: 0.2-1%; Trimethylbenzoyl-diphenyl phosphine oxide: 0.5-3%; Acrylate leveling agent: 1-3%; Polyurea modified polyurethane rheological aid: 0.2-1.2%; Trimethylolpropane triacrylate: 5-15%; Gamma-aminopropyl triethoxysilane coupling agent: 0.8-2%; 2-hydroxy-4-methoxybenzophenone: 0.1-0.4%; Tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid] pentaerythritol ester: 0.1-0.3%; The anti-settling powder uses nano-silica with a silane-modified surface, and the particle size is 50-100 nm.

[0019] Preferably, the modified polyurethane acrylate uses Lankruz L-8400C from Guangdong Lankruz New Material Co., Ltd.; the high-functionality aliphatic polyurethane acrylate uses Bawei BW8292 from Guangzhou Bawei New Material Technology Co., Ltd.; the special modified epoxy acrylate resin uses Lankruz L-6118 from Guangdong Lankruz New Material Co., Ltd. The nano-silica uses UZ-S03D from Suzhou UZ Nano Material Co., Ltd.; the matting powder uses Grace RAD-2105 from the United States Grace Company; the 1-hydroxycyclohexyl phenyl ketone uses Tianjin Jiuri 184 from Tianjin Jiuri New Material Co., Ltd.; the trimethylbenzoyl-diphenyl phosphine oxide uses Tianjin Jiuri TPO from Tianjin Jiuri New Material Co., Ltd.; the magnesium silicate mineral uses Guangdong Housheng 6000-mesh talc powder from Foshan Housheng Chemical Co., Ltd.; the dispersant uses BYK-20084 from Germany BYK Chemical Corporation; the defoaming agent uses TEGO920 from Germany Evonik Group; the acrylate leveling agent uses BYK-358N from Germany BYK Corporation; and the trimethylolpropane triacrylate uses Lianbang Changrunfa YTM6350 from Guangdong Lianbang Changrunfa Science and Technology Material Co., Ltd.

[0020] It should be noted that: in the present application, the modified polyurethane acrylate generally introduces flexible segments such as polyester and polyether, the long molecular chain acts as an elastic hinge in the curing network, can absorb and disperse external stress, so that the elongation at break is greater than or equal to 150%, can meet the deformation demand caused by folding or cutting of aluminum substrate, avoid coating cracking, significantly improve the bending resistance of coating. The high functionality aliphatic polyurethane acrylate contains multiple high functionality double bonds and does not contain easily yellowing aromatic ring, forms a rigid network with high crosslinking density when UV curing, can effectively inhibit the thermal motion of resin molecular chain in high temperature environment, reduce the exposure probability of oxidation site from the root; the molecular structure has excellent acid and alkali resistance, improves the comprehensive mechanical properties, further strengthens the resistance and thermal stability of the coating, and the scratch resistance is outstanding. The thermal decomposition temperature of the special modified epoxy acrylate can reach more than 250 DEG C, which can effectively reduce the high temperature oxidation yellowing; the hardness of the cured paint film can reach more than 3H, and it has excellent acid and alkali resistance, providing the basic heat resistance, hardness and chemical stability of the coating. The nano silicon dioxide is surface silane modified nano silicon dioxide, which has the characteristics of small particle size and large specific surface area, and has excellent compatibility with resin after silane modification, and has the traditional anti-sedimentation effect, and after high shear dispersion, the nano particles can be uniformly dispersed in the crosslinked network, producing "nano reinforcement effect", greatly improving the wear resistance, scratch resistance and overall mechanical strength of the paint film, while not affecting the flexibility of the paint film; the polyurea modified polyurethane rheological agent has the characteristics of forming extremely long fibrous structure in one-dimensional direction, and these fibers form a reversible three-dimensional network through hydrogen bond, which endows the coating with thixotropy of thick at rest and thin under shear, which can prevent sagging and sedimentation. The molecular characteristics of the gamma-aminopropyl triethoxysilane coupling agent are that it contains two different active groups, the ethoxyl group hydrolyzes to form a firm Si-O-Al covalent bond with the hydroxyl group on the surface of the aluminum substrate, and the amino group at the organic end reacts with the resin system or forms a strong hydrogen bond, thereby forming a molecular bond between the inorganic substrate and the organic coating. It synergistically acts with the resin system, not only solves the problem of 0 level of hundred grid adhesion, but also greatly enhances the adhesion durability of the paint film in wet state and chemical corrosion environment, so that the UV matte finish of the present application can resist acid and alkali etching liquid without falling off and bubbling.In the present application, the photoinitiator is compounded with 1-hydroxycyclohexyl phenyl ketone and trimethyl benzoyl-diphenyl phosphine oxide, the 1-hydroxycyclohexyl phenyl ketone is short-wave UV absorption, fast surface drying speed, anti-oxygen inhibition, the trimethyl benzoyl-diphenyl phosphine oxide is long-wave UV absorption, strong penetration, beneficial to deep curing, complementary to each other, realizing the efficient full-waveband curing of "surface drying-deep drying" synchronization; the 2-hydroxy-4-methoxy benzophenone can absorb UV energy, the tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid] pentaerythritol ester can terminate the free radical chain reaction generated by thermal oxidation degradation, and the two synergistically act, so that the color difference ΔE of the paint film after experiencing extreme high temperature of 220℃+260℃ can be stably less than 1.5, and can resist UV aging for a long time. In the present application, the magnesium silicate mineral adopts talc powder, the lamellar structure of which can enhance the mechanical properties of the coating, and at the same time, help to improve the leveling property and stability of the coating, so that the coating is more likely to form a uniform film layer during the construction process. The wetting dispersant adopts an acrylate copolymer solution, which can significantly improve the wettability and dispersibility of the system to fillers and powders, ensure uniform distribution of talc powder, nano-silicon dioxide and the like in the coating, avoid agglomeration, and ensure the consistency of the coating performance. The leveling agent adopts an acrylate leveling agent to assist the fillers and powders to spread uniformly on the substrate surface, reduce the coating defects caused by uneven distribution of the powders, and improve the flatness and appearance quality of the paint film.

[0021] A preparation process of an aluminum substrate UV matte finish paint is applied to the aluminum substrate UV matte finish paint and includes the following steps. S1, according to the batch, select the appropriate production cylinder, confirm that the inner wall of the cylinder has been cleaned, and the discharge valve is in the closed state.

[0022] S2, first put in 1 / 2 amount of trimethylolpropane triacrylate and all dispersants, disperse at a medium speed of 1000±200 r / min, and then slowly and uniformly add nano-silicon dioxide; after the addition is completed, switch to high-speed dispersion at 1500±200 r / min, and continuously disperse for 20-25 min, until the slurry fineness is ≤15 μm, to obtain a uniform translucent nano-pre-dispersed slurry; this step uses high shear force to de-agglomerate the nano-particles, and forms a stable coating layer on the surface of the nano-particles by using the dispersant, laying a foundation for the subsequent enhancement.

[0023] S3, in the nano-slurry prepared in the previous step, sequentially add all the modified polyurethane acrylate, high-functionality aliphatic polyurethane acrylate and special modified epoxy acrylate resin, disperse at a medium speed of 1000±200 r / min, continuously disperse for 15-20 min, so that the resin and the nano-slurry are fully fused, and whether the solution is uniform is observed.

[0024] S4. After the previous dispersion step is completed, continue to add all the magnesium silicate minerals and matting powder, start the cooling water system, control the cylinder temperature to not exceed 40℃, and then perform high-speed dispersion at 1500±200 rpm for 30-35 minutes. After dispersion, check the fineness to ≤25μm. This step, through forced cooling, avoids the heat generated by high-speed dispersion from causing a sudden increase in system viscosity or prepolymerization, ensuring the optimal dispersion state of matting powder and mineral filler, thereby obtaining a more uniform matte effect and stability.

[0025] S5. Reduce the rotation speed to a medium speed of 1000±200 rpm, and add all the defoamer, acrylate leveling agent and polyurea modified polyurethane rheology modifier in sequence. Maintain medium speed dispersion for 10-15 minutes until the rheology modifier is completely swollen and the system exhibits a uniform thixotropic state.

[0026] S6. Disperse at a low speed of 500±100 rpm, add the remaining trimethylolpropane triacrylate to adjust the final viscosity; then, add all of the γ-aminopropyltriethoxysilane coupling agent, 2-hydroxy-4-methoxybenzophenone, and pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] in sequence, disperse at a low speed of 500±100 rpm for 10 minutes to ensure uniform mixing; this step is carried out at low temperature and low shear, which effectively prevents the hydrolysis and self-condensation of the silane coupling agent, protects the molecular structure of the ultraviolet absorber and antioxidant from being destroyed, and ensures their long-term stability.

[0027] S7. Maintain a low dispersion speed of 500±100 rpm, add 1-hydroxycyclohexylphenyl ketone and trimethylbenzoyl-diphenylphosphine oxide, disperse for 5-10 min to ensure complete dissolution and uniform mixing.

[0028] This invention provides a UV matte topcoat for aluminum substrates, and the formulations for various embodiments and comparative examples are shown in Table 1 below: Table 1: Formulation Design of Examples and Comparative Examples (mass percentage %) Component Name Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 Comparative Example 3 Modified polyurethane acrylate (L-8400C) 15.0 10.0 12.0 15.0 0.0 30.0 25.0 High functionality aliphatic polyurethane acrylate (BW8292) 30.0 25.0 30.0 28.0 55.0 0.0 40.0 Special modified epoxy acrylate resin (L-6118) 20.0 30.0 20.0 25.0 25.0 50.0 0.0 Dispersant (BYK-20084) 1.0 1.5 1.5 1.0 1.0 1.0 1.0 Defoamer (TEGO 920) 0.3 0.3 0.3 0.3 0.3 0.3 0.3 Nano-silica (UG-S03D) 2.0 1.5 2.5 1.5 2.0 2.0 2.0 Magnesium silicate mineral (6000 mesh talc) 12.0 10.0 12.0 12.0 12.0 12.0 12.0 Matting powder (RAD-2105) 3.0 8.0 6.0 3.0 3.0 3.0 3.0 1-hydroxycyclohexyl phenyl ketone (184) 0.5 0.8 0.6 0.5 0.5 0.5 0.5 Trimethylbenzoyl-diphenylphosphine oxide (TPO) 1.5 2.0 1.8 1.5 1.5 1.5 1.5 Acrylate leveling agent (BYK-358N) 1.5 2.0 1.8 1.5 1.5 1.5 1.5 Polyurea modified polyurethane rheology aid 0.4 1.0 0.4 0.4 0.4 0.4 0.4 Trimethylolpropane triacrylate (YTM6350) 10.0 5.0 8.0 8.0 10.0 10.0 10.0 Gamma-aminopropyl triethoxysilane coupling agent 1.0 1.5 1.2 1.0 1.0 1.0 1.0 2-hydroxy-4-methoxybenzophenone (UV absorber) 0.2 0.3 0.2 0.2 0.2 0.2 0.2 Antioxidant (1076) 0.2 0.2 0.2 0.2 0.2 0.2 0.2 Total 100 100 100 100 100 100 100 As can be seen from Table 1 above, Comparative Example 1 lacks the main component modified polyurethane acrylate compared with the Example; Comparative Example 2 lacks the main component high-functionality aliphatic polyurethane acrylate compared with the Example; and Comparative Example 3 lacks the main component special modified epoxy acrylate resin compared with the Example.

[0029] Based on the various proportions above, and using the above-described preparation process for UV matte topcoat on aluminum substrates, the UV matte topcoats obtained in Examples 1-4 and Comparative Examples 1-3 were subjected to performance tests. All tests were conducted according to HG / T 3655-2012, and the performance index test results are shown in Tables 2 and 3 below: Test results of Examples 1-4 Table 2: Test Item Test Method and Condition Example 1 Example 2 Example 3 Example 4 Adhesion Crosshatch method (0-5 scale, 0 best) 0 0 0 0 Pencil hardness Mitsubishi pencil, 750 g load 3H 4H 3H 4H Flexibility 180° fold No cracks, no powder loss No cracks, no powder loss No cracks, no powder loss No cracks, no powder loss Impact resistance 500 g, frontal impact No cracking, no peeling of the coating film No cracking, no peeling of the coating film No cracking, no peeling of the coating film No cracking, no peeling of the coating film Acid resistance pH = 2 aqueous solution, room temperature immersion for 24 h No change No change No change No change Alkali resistance pH = 9 aqueous solution, room temperature immersion for 24 h No change Slight loss of gloss No change No change Yellowing resistance ΔE (260°C / 2h) 1.2 1.5 1.3 1.4 Appearance (60° gloss) Gloss unit (GU) 15 GU 8 GU 10 GU 12 GU Surface tension Dyne pen (mN / m) 44 42 43 44 Scratch resistance Aluminum sheet inclined angle wiping, 500 g load No obvious scratches No obvious scratches No obvious scratches No obvious scratches Thermal storage stability State after 168 h oven storage at 50°C Uniform, no gel, easy to stir Uniform, slightly thickened, easy to stir Uniform, no gel, easy to stir Uniform, no gel, easy to stir Test results of Comparative Examples 1-3 Table 3: Test Item Test Method and Condition Comparative Example 1 Comparative Example 2 Comparative Example 3 Adhesion Crosshatch method (0-5 scale, 0 best) 2 0 3 (partial peeling) Pencil hardness Mitsubishi pencil, 750 g load 5H B 2H Flexibility 180° fold Severe cracking, large area powder loss No cracks Slight cracking, small amount of powder loss Impact resistance 500 g, frontal impact Severe cracking of the coating film No cracking, no peeling of the coating film Slight cracking of the coating film Acid resistance pH = 2 aqueous solution, room temperature immersion for 24 h No change Severe black spots, bubbling Slight black spots Alkali resistance pH = 9 aqueous solution, room temperature immersion for 24 h Bubbling, peeling Corroded, paint film dissolved No change Yellowing resistance ΔE (260°C / 2h) 1.8 2.5 1.5 Appearance (60° gloss) Gloss unit (GU) 20 GU 5 GU 18 GU Surface tension Dyne pen (mN / m) 40 38 41 Scratch resistance Aluminum sheet inclined angle wiping, 500 g load Dense obvious scratches Coating layer was scratched Slight scratches Thermal storage stability State after 168 h oven storage at 50°C Severe precipitation, caking homogeneous, slight precipitate homogeneous, slight precipitate As can be seen from the above Tables 2 and 3, Example 1 adopts a balanced proportion of three resins of modified polyurethane acrylate, high-functionality aliphatic polyurethane acrylate and specially modified epoxy acrylate resin, and the moderate amount of nano-silica is 2%, and the test results of all items reach the "excellent" or "good" level, which reflects the balance and reliability of the formula design of the present application; the dyne value of 44 and excellent thermal storage stability prove that the formula system of the present application is cross-linked and dense and storage stable.

[0030] Example 2 obtains the highest 4H hardness and the lowest 8GU matte gloss by increasing the proportion of high-functionality aliphatic polyurethane acrylate and specially modified epoxy acrylate resin, and increasing the amount of matting powder, although the flexibility test still passes due to the extremely high cross-linking density, but the alkali resistance appears "slight loss of gloss", but this just shows that the formula can be precisely controlled within a certain range by adjusting the components to meet the specific application scenarios.

[0031] Example 3 slightly increases the amount of high-functionality aliphatic polyurethane acrylate and nano-silica based on Example 1, which makes it have more outstanding scratch resistance while maintaining excellent comprehensive performance, which reflects the synergistic reinforcement effect of nano-materials and high cross-linking network.

[0032] Example 4 further increases the proportion of specially modified epoxy acrylate resin, and optimizes the proportion of other components. Its results are the most comprehensive and robust chemical resistance among all examples, with no changes in acid and alkali, while maintaining high hardness of 4H and perfect flexibility, which is very suitable for aluminum substrates in harsh corrosive environments.

[0033] Comparative Example 1 lacks modified polyurethane acrylate, and the system is dominated by high-functionality aliphatic polyurethane acrylate and specially modified epoxy acrylate resin, which becomes too rigid, which is manifested as: serious cracking and powder falling off after 180° bending, serious cracking after impact resistance, adhesion falling to level 2, which proves that without flexible resin to provide toughening and stress buffering, the rigid network cannot withstand deformation; serious precipitation and caking, because the rigid network cannot effectively wrap and stabilize the filler particles; it can be seen from this that modified polyurethane acrylate is the key to ensure the toughness and processability of the paint film and is indispensable.

[0034] Comparative Example 2 lacks high-functionality aliphatic polyurethane acrylate, the system is dominated by modified polyurethane acrylate and special modified epoxy acrylate resin, and the crosslinking density is seriously insufficient, which is manifested as: the pencil hardness is only B, like soft plastic; it is corroded and dissolved under alkaline resistance, and serious black spots appear under acid resistance; the coating is broken in the scratch resistance test, which cannot provide basic protection; the viscosity decreases significantly after heat storage, indicating that the network strength is insufficient and flow occurs; it can be seen that high-functionality aliphatic polyurethane acrylate is the skeleton of hardness, wear resistance and chemical resistance, and is the cornerstone of performance.

[0035] Comparative Example 3 lacks special modified epoxy acrylate resin, and the system is dominated by modified polyurethane acrylate and high-functionality aliphatic polyurethane acrylate, lacking the strongest adhesion provider and chemical resistance enhancing component, which is manifested as: the crosshatch test is grade 3 and partially falls off, which is the root cause of a small amount of powder falling off and slight cracking under impact; slight black spots appear under acid resistance, proving that the barrier effect of the coating on acid medium is weakened; the surface tension is low, and the scratch resistance is only "slight scratch"; it can be seen that special modified epoxy acrylate resin is the core of realizing strong adhesion, excellent acid resistance and dense paint film structure.

[0036] The present application solves the long-standing technical contradiction in the UV coating field that "high hardness" and "high flexibility" cannot be achieved at the same time by compounding modified polyurethane acrylate, high-functionality aliphatic polyurethane acrylate and special modified epoxy acrylate resin, and the coating has top-level adhesion, excellent acid and alkali corrosion resistance and super-strong anti-yellowing performance, providing all-round and lasting protection for aluminum substrates; nano-silicon dioxide not only plays a role in preventing sedimentation in the dense resin network, but also brings significant wear resistance and scratch resistance enhancement effect; and the combination of the composite light stabilizing system and the aliphatic resin improves the yellowing resistance to a new height in the industry.

[0037] The above is only a preferred embodiment of the present application, and does not limit the present application in any form; any person skilled in the art can easily implement the present application according to the description and the above; however, any equivalent changes, modifications and evolution of the above disclosed technical content without departing from the scope of the technical solutions of the present application are equivalent embodiments of the present application; at the same time, any equivalent changes, modifications and evolution of the above embodiments according to the essential technology of the present application are still within the scope of the present application.

Claims

1. An aluminum substrate UV matte finish paint, characterized by, By mass percent, the following components are included: Modified polyurethane acrylate: 10-20%; High functionality aliphatic polyurethane acrylate: 25-32%; Special modified epoxy acrylate resin: 18-30%; Dispersing agent: 0.5-2%; Defoaming agent: 0.1-0.5%; Anti-settling powder: 1-3%; Magnesium silicate mineral: 10-15%; Matting powder: 1-10%; 1-hydroxycyclohexyl phenyl ketone: 0.2-1%; Trimethylbenzoyl-diphenyl phosphine oxide: 0.5-3%; Acrylate leveling agent: 1-3%; Polyurea modified polyurethane rheological aid: 0.2-1.2%; Trimethylolpropane triacrylate: 5-15%.

2. The aluminum substrate UV matte finish of claim 1, wherein, By mass percent, the following components are also included: Gamma-aminopropyl triethoxysilane coupling agent: 0.8-2%; 2-hydroxy-4-methoxy benzophenone: 0.1-0.4%; Tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid] pentaerythritol ester: 0.1-0.3%. The anti-settling powder uses nano-silica with a silane-modified surface, and the particle size is 50-100 nm.

3. The aluminum substrate UV matte finish of claim 2, wherein, By mass percent, the following components are included: Modified polyurethane acrylate: 10-15%; High functionality aliphatic polyurethane acrylate: 27-32%; Special modified epoxy acrylate resin: 18-25%; Dispersing agent: 1-2%; Defoaming agent: 0.1-0.5%; Nano-silica: 1.5-3%; Magnesium silicate mineral: 10-15%; Matting powder: 4-10%; 1-hydroxycyclohexyl phenyl ketone: 0.2-1%; Trimethylbenzoyl-diphenyl phosphine oxide: 0.5-3%; Acrylate leveling agent: 1-3%; Polyurea modified polyurethane rheological aid: 0.2-0.5%; Trimethylolpropane triacrylate: 5-10%; Gamma-aminopropyl triethoxysilane coupling agent: 0.8-2%; 2-hydroxy-4-methoxy benzophenone: 0.1-0.4%; Tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid] pentaerythritol ester: 0.1-0.3%.

4. The aluminum substrate UV matte finish of claim 2, wherein, By mass percent, the following components are included: Modified polyurethane acrylate: 10-15%; High functionality aliphatic polyurethane acrylate: 27-32%; Special modified epoxy acrylate resin: 18-25%; Dispersing agent: 1-2%; Defoaming agent: 0.1-0.5%; Nano-silica: 1.5-3%; Magnesium silicate mineral: 10-15%; Matting powder: 4-10%; 1-hydroxycyclohexyl phenyl ketone: 0.2-1%; Trimethylbenzoyl-diphenyl phosphine oxide: 0.5-3%; Acrylate leveling agent: 1-3%; Polyurea modified polyurethane rheological aid: 0.2-0.5%; Trimethylolpropane triacrylate: 5-10%; Gamma-aminopropyl triethoxysilane coupling agent: 0.8-2%; 2-hydroxy-4-methoxy benzophenone: 0.1-0.4%; Tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid] pentaerythritol ester: 0.1-0.3%. By mass percent, the following components are included: Modified polyurethane acrylate: 10-15%; High functionality aliphatic polyurethane acrylate: 27-32%; Special modified epoxy acrylate resin: 18-25%; Dispersing agent: 1-2%; Defoaming agent: 0.1-0.5%; Nano-silica: 1.5-3%; Magnesium silicate mineral: 10-15%; Matting powder: 4-10%; 1-hydroxycyclohexyl phenyl ketone: 0.2-1%; Trimethylbenzoyl-diphenyl phosphine oxide: 0.5-3%; Acrylate leveling agent: 1-3%; Polyurea modified polyurethane rheological aid: 0.2-0.5%; Trimethylolpropane triacrylate: 5-10%; Gamma-aminopropyl triethoxysilane coupling agent: 0.8-2%; 2-hydroxy-4-methoxy benzophenone: 0.1-0.4%; Tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid] pentaerythritol ester: 0.1-0.3%.

5. The aluminum substrate UV matte finish of any of claims 2-4, wherein, The modified polyurethane acrylate adopts Lanxess L-8400C; the high-functionality aliphatic polyurethane acrylate adopts Everspring BW8292; and the special modified epoxy acrylate resin adopts Lanxess L-6118.

6. The aluminum substrate UV matte finish of any of claims 2-4, wherein, The nano-silica adopts Optimized Zirconium UG-S03D; and the matting powder adopts Grex RAD-2105.

7. The aluminum substrate UV matte finish of any of claims 2-4, wherein, The 1-hydroxycyclohexyl phenyl ketone adopts Tianjin Jiuri 184; and the trimethylbenzoyl-diphenyl phosphine oxide adopts Tianjin Jiuri TPO.

8. The aluminum substrate UV matte finish of any of claims 2-4, wherein, The magnesium silicate mineral adopts Guangdong Housheng 6000-mesh talcum powder; the dispersing agent adopts BYK-20084; the defoaming agent adopts TEGO920; the acrylate leveling agent adopts BYK-358N; and the trimethylolpropane triacrylate adopts Longrunfa YTM6350 of LiBong.

9. A process for the preparation of an aluminum substrate UV matte finish, characterized in that, The aluminum substrate UV matte finish paint according to any one of the preceding claims 1-8 comprises the following steps: S1. Selecting a suitable production cylinder according to the batch, confirming that the inner wall of the cylinder has been cleaned, and that the discharge valve is in a closed state; S2. First, 1 / 2 of the trimethylolpropane triacrylate and all of the dispersing agent are added, and medium-speed dispersion is performed at 1000±200 rpm, and then the nano-silica is slowly and evenly added; after the addition is completed, high-speed dispersion is switched to 1500±200 rpm, and the dispersion is continuously performed for 20-25 min, until the fineness of the slurry is ≤15 μm, to obtain a uniform translucent nano-pre-dispersed slurry; S3. In the nano-slurry prepared in the previous step, all of the modified polyurethane acrylate, the high-functionality aliphatic polyurethane acrylate, and the special modified epoxy acrylate resin are sequentially added, medium-speed dispersion is adopted at 1000±200 rpm, and the dispersion is continuously performed for 15-20 min, so that the resin and the nano-slurry are fully fused, and whether the solution is uniform is observed; S4. After the dispersion in the previous step is completed, all of the magnesium silicate mineral and the matting powder are continuously added, the cooling water system is started, the temperature of the cylinder body is controlled to be not more than 40℃, and then high-speed dispersion is performed at 1500±200 rpm, and the dispersion is continuously performed for 30-35 min; After the dispersion is completed, the fineness is detected to be ≤25 μm; S5. The speed is reduced to medium speed of 1000±200 rpm, all of the defoaming agent, the acrylate leveling agent, and the polyurea modified polyurethane rheological additive are sequentially added, medium-speed dispersion is maintained for 10-15 min, until the rheological additive is completely swollen, and the system presents a uniform thixotropic state; S6. Dispersion is performed at low speed of 500±100 rpm, the remaining trimethylolpropane triacrylate is added, and is used for adjusting the final viscosity; subsequently, all of the γ-aminopropyl triethoxysilane coupling agent, 2-hydroxy-4-methoxybenzophenone, and tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionic acid] pentaerythritol ester are sequentially added, and low-speed dispersion is performed at 500±100 rpm for 10 min, to ensure uniform mixing. S7. Maintaining the low speed dispersion of 500 ± 100 rpm, add 1-hydroxycyclohexyl phenyl ketone and trimethylbenzoyl-diphenylphosphine oxide and disperse for 5-10 minutes to ensure complete dissolution and uniform mixing.