Colored dual-curing UV paint and preparation method thereof

Abstract

The invention particularly relates to colored dual-curing UV paint and a preparation method thereof. The UV paint is prepared from the following raw materials in parts by weight: 15 to 20 parts of trifunctional aliphatic polyurethane acrylic resin, 12 to 16 parts of organic silicon modified polyurethane acrylate prepolymer, 5 to 8 parts of polyether type polyurethane acrylate, 10 to 15 parts of organic silicon-acrylic hybrid resin, 4 to 9 parts of blocked isocyanate, 15 to 25 parts of diluent and 1 to 3 parts of pigment. 3-6 parts of amino modified silicon dioxide, 1-3 parts of a photoinitiator and 0.1-0.3 part of a flatting agent. According to the UV paint, the adhesion, high wear resistance, weather resistance and hydrolysis resistance of the UV paint are remarkably improved by compounding multiple resins and a processing aid, the production efficiency is improved through a dual-curing mechanism combining UV curing and thermocuring, and meanwhile, complete curing and durability of the UV paint are guaranteed; in addition, VOCs emission is greatly reduced, and the low-VOCs environmental protection requirement is met.

Description

Technical Field

[0001] The invention relates to the technical field of coating preparation, in particular to a colored dual-curing UV paint and a preparation method thereof. Background Art

[0002] With the continuous development of the automotive industry, consumers are placing higher demands on the aesthetics, durability, and environmental friendliness of automotive interiors. Currently, the main types of coatings used for automotive interiors include solvent-based, water-based, and powder coatings. Solvent-based coatings are known to emit high levels of volatile organic compounds (VOCs), which can pose a threat to human health and the environment. Water-based coatings are more environmentally friendly, but they dry slowly, making the coating performance less than ideal for high-end vehicle interiors. Powder coatings, on the other hand, require a complex application process, making it difficult to achieve uniform coating quality when applied to complex interior components.

[0003] As we all know, the main challenges facing traditional automotive interior coatings are high VOC emissions and the difficulty of achieving balanced performance using a single reaction system. Some interior paints lack optimal weather resistance, abrasion resistance, and adhesion, making them unable to meet the demands of long-term automotive interior use. For example, car interiors are frequently exposed to sunlight, causing ordinary interior paints to fade and age. Friction from daily use can also easily cause the paint surface to wear, affecting its appearance.

[0004] To this end, a lot of research work has been carried out within the industry. For example, Chinese invention patent application number 201710320766.1 discloses a UV coating for automotive interiors. It uses a large amount of volatile organic compound solvents, resulting in significantly high VOC emissions. Moreover, when cured solely through UV curing, it is difficult for UV light to evenly illuminate shadowed areas of complex structural components in automotive interiors, which may result in incomplete curing. This also has a significant impact on the coating hardness and long-term stability in these areas. Another example is Chinese invention patent application number 201811090758.3, which discloses a colored dual-curing UV coating for automotive interior parts. It uses tri-, tetra-, and hexa-functional aliphatic polyurethane acrylic resins as the main raw materials, combined with TMPTA monomer. The overall reactivity is high, which can easily lead to increased low-temperature brittleness and difficulty in balancing crosslinking density and flexibility. Summary of the Invention

[0005] The purpose of the present invention is to solve the above-mentioned deficiencies in the prior art and to provide a colored dual-curing UV paint and a preparation method thereof.

[0006] The object of the present invention is achieved through the following technical solution: The present invention provides a colored dual-curing UV paint, comprising the following raw materials in parts by weight: 15-20 parts of trifunctional aliphatic polyurethane acrylic resin, 12-16 parts of silicone-modified polyurethane acrylate prepolymer, 5-8 parts of polyether polyurethane acrylate, 10-15 parts of silicone-acrylic hybrid resin, 4-9 parts of blocked isocyanate, 15-25 parts of diluent, 1-3 parts of pigment, 3-6 parts of amino-modified silica, 1-3 parts of photoinitiator, and 0.1-0.3 parts of leveling agent.

[0007] In the present invention, by compounding a variety of resins such as trifunctional aliphatic polyurethane acrylic resin, silicone-modified polyurethane acrylate prepolymer, polyether polyurethane acrylate, silicone-acrylic hybrid resin, etc., the coating is given excellent mechanical properties, especially the wear resistance, weather resistance and hydrolysis resistance of UV paint are significantly improved. The addition of blocked isocyanate enhances the curing effect and durability of the coating; the diluent, black paste, amino-modified silica, photoinitiator, leveling agent and other ingredients work together to give the coating good fluidity, weather resistance and curing speed. Compared with traditional solvent-based coatings, the one-coat colored dual-curing UV paint of the present invention not only performs well in environmental performance and effectively reduces VOCs emissions, but also has significant improvements in performance such as weather resistance, wear resistance and adhesion, and can better meet the market demand for automotive interior paint.

[0008] Furthermore, the trifunctional aliphatic polyurethane acrylic resin has an average functionality of 2.8-3.2 and a hydroxyl value of 30-50 mgKOH / g.

[0009] Furthermore, the preparation method of the organosilicon-modified polyurethane acrylate prepolymer includes the following steps: placing IPDI and acetone in a reactor, maintaining a nitrogen atmosphere after emptying, raising the temperature to 50°C, slowly adding amino-terminated PDMS dropwise therein, and adding 0.03-0.1wt% bismuth-zinc composite catalyst to react for 2-3 hours, then raising the temperature to 60°C, adding PPG therein for chain extension, and detecting that the -NCO group content in the system reaches the theoretical value and no longer decreases, at which point the reaction can be considered to have reached equilibrium. Subsequently, HEMA and 0.05-0.3wt% hydroquinone are added thereto to continue the reaction. After the -NCO group content is determined to be close to zero, the solvent is removed by reduced pressure distillation at 60°C and -0.095MPa for 2-3 hours to obtain the organosilicon-modified polyurethane acrylate prepolymer.

[0010] Furthermore, the R value of the silicone-modified polyurethane acrylate prepolymer reaction system is 1.1, the molar ratio of IPDI, PPG and HEMA is 2.2:1:2, the amino-terminated PDMS accounts for 15-25% of the total mass of the prepolymer, and the molecular weight of the amino-terminated PDMS is 2000-4000 g / mol.

[0011] The silicone-modified polyurethane acrylate prepolymer prepared by the above method exhibits high elasticity, heat resistance, and low surface energy. The PDMS soft segment provides excellent flexibility, while the introduction of highly stable siloxy bonds enhances the material's resistance to high-temperature yellowing. The silicone modification results in a low surface energy, imparting the material with easy-to-clean, fingerprint-resistant, and hydrophobic properties. This reaction system eliminates the presence of residual small molecule siloxanes, thereby addressing the odor-prone nature of UV lacquers.

[0012] Furthermore, the preparation method of the polyether polyurethane acrylate comprises the following steps: fully dissolving polypropylene glycol (PPG) in acetone, maintaining a nitrogen atmosphere after evacuation, raising the temperature to 40°C, and adding IPDI and 0.02-0.05 wt% of a bismuth-based catalyst to react until the -NCO group content in the system reaches 50-80% of the theoretical value. Subsequently, the temperature is raised to 70°C, and HPA and p-methylphenyl ether are added to continue the reaction. The infrared spectrum at 2267 cm -1 The disappearance of the characteristic peak of the -NCO group at is considered to be the end of the reaction, and the solvent is removed by reduced pressure distillation at 60° C. and −0.095 MPa for 2-3 hours to obtain the polyether polyurethane acrylate.

[0013] Furthermore, the PPG is a primary hydroxyl terminated PPG with a molecular weight of 2000-4000 g / mol and a hydroxyl value of 28-56 mg KOH / g.

[0014] In the present invention, the polyether polyurethane acrylate prepared by the above method has good flexibility, hydrolysis resistance and heat resistance.

[0015] Furthermore, the blocked isocyanate is ε-caprolactam blocked isocyanate.

[0016] Furthermore, the diluent is at least one of dipropylene glycol diacrylate (DPGDA), isodecyl acrylate IDA, and isobornyl acrylate IBOA. Preferably, the diluent is a compound of isobornyl acrylate and dipropylene glycol diacrylate in a mass ratio of 1.5:1.

[0017] Furthermore, the pigment is preferably carbon black paste.

[0018] Furthermore, the photoinitiator is at least one of TPO, 819, and 184. As a preferred embodiment of the present invention, 0.1-0.3 parts of an amine accelerator is also included, and the amine accelerator is an ammonia-modified acrylate.

[0019] Furthermore, the leveling agent is a fluorine-modified acrylate leveling agent.

[0020] Furthermore, the amino-modified silica is obtained by placing nano-silica in a 0.5% silane coupling agent and stirring at high speed. The silane coupling agent is preferably KH-550, which can eliminate the water absorption of the surface hydroxyl groups of the nano-silica and enhance the chemical bonding of silicon oxide with the resin.

[0021] Furthermore, the single-coat, dual-curing UV paint further comprises 0.8-1.0 parts of a weathering agent, which is a combination of one or more of a UV absorber, a hindered amine light stabilizer, and an antioxidant. Preferably, the weathering agent is a combination of a UV absorber and a hindered amine light stabilizer at a mass ratio of 1:1.5-2, whereby the UV absorber and the hindered amine light stabilizer synergistically exert a long-lasting anti-UV aging effect.

[0022] Furthermore, the one-coat colored dual-curing UV paint also includes 0.5-3 parts of a modified polypropylene adhesion promoter, wherein the modified polypropylene adhesion promoter is at least one of chlorinated polyolefin, maleic anhydride grafted polypropylene or phosphate modified acrylate.

[0023] The present invention also provides a method for preparing the above-mentioned colored dual-curing UV paint, comprising the following steps:

[0024] Step S1: mixing the pigment with a portion of the diluent, and grinding the mixture with a grinder to a fineness of less than 5 μm;

[0025] Step S2: stirring the trifunctional aliphatic polyurethane acrylate resin, the silicone-modified polyurethane acrylate prepolymer, the polyether polyurethane acrylate, and the silicone-acrylic hybrid resin in sequence at 25-30° C. until completely dispersed, and then adding a leveling agent, a weathering agent, or an adhesion promoter according to the formulation requirements;

[0026] Step S3, adding amino-modified silica and the pigment obtained in step S1, and uniformly dispersing them with a high-speed dispersant and the remaining diluent;

[0027] Step S4: adding blocked isocyanate thereto, and then adding a photoinitiator under light-proof conditions, adjusting the system viscosity to 1000-1200 mPa·s, and obtaining the one-coat colored dual-curing UV paint after filtering.

[0028] Furthermore, the curing method of the colored dual-curing UV paint is as follows: spraying the obtained UV paint on the surface of the cleaned material, irradiating it with a UV lamp, and then baking it at 80-100°C for 20-30 minutes, and then cooling it to complete the curing process. The wavelength of the UV lamp is 300-400nm, and the power is 80-120mW / cm 2 , time is 10-15s.

[0029] The beneficial effects of the present invention are:

[0030] (1) The single-coat, dual-curing UV paint produced by the present invention utilizes a dual-curing mechanism of UV curing and thermal curing, synergistically resolving the problem of insufficient curing of complex structural components by single UV curing. The photoinitiator initiates polymerization of the resin and diluent under UV light, achieving rapid surface drying and initial curing. The blocked isocyanate is then unblocked under heating, reacting with the resin to achieve deep curing and complete crosslinking, thereby improving the production efficiency and quality stability of the UV paint.

[0031] (2) The present invention adopts a multi-resin compound to achieve balanced mechanical properties. The trifunctional aliphatic polyurethane acrylate provides hardness and scratch resistance, the polyether polyurethane acrylate enhances flexibility and water resistance, the silicone modified resin improves flexibility and wear resistance, and the amino-modified silica is combined to enhance hardness and scratch resistance, thereby achieving a balance between hardness and flexibility. In addition, with the cooperation of weathering additives, it helps to synergistically enhance the weather resistance of the UV paint and inhibit coating aging, making it suitable for use in automotive interiors exposed to light and a wide temperature range for a long time.

[0032] (3) The present invention adopts active diluent to participate in the curing reaction, which reduces the use of volatile organic solvents, ensures the environmental friendliness of the UV paint, and reduces VOCs emissions. DETAILED DESCRIPTION

[0033] In order to facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the embodiments. The contents mentioned in the embodiments are not intended to limit the present invention.

[0034] Example 1

[0035] This embodiment provides a colored dual-curing UV paint, comprising the following raw materials in parts by weight: 18 parts of trifunctional aliphatic polyurethane acrylate resin, 14 parts of silicone-modified polyurethane acrylate prepolymer, 6 parts of polyether polyurethane acrylate, 12 parts of silicone-acrylic hybrid resin, 7 parts of blocked isocyanate, 17 parts of diluent, 2 parts of pigment, 4.5 parts of amino-modified silica, 2.3 parts of photoinitiator, and 0.2 parts of leveling agent.

[0036] Furthermore, the trifunctional aliphatic polyurethane acrylic resin has an average functionality of 3 and a hydroxyl value of 30 mgKOH / g.

[0037] Furthermore, the preparation method of the organosilicon-modified polyurethane acrylate prepolymer includes the following steps: placing IPDI and acetone in a reactor, maintaining a nitrogen atmosphere after emptying, raising the temperature to 50°C, slowly adding amino-terminated PDMS dropwise therein, and adding 0.05wt% bismuth-zinc composite catalyst to react for 3 hours, then raising the temperature to 60°C, adding PPG therein for chain extension, and detecting that the -NCO group content in the system reaches the theoretical value and no longer decreases, at which point the reaction can be considered to have reached equilibrium. Subsequently, HEMA and 0.12wt% hydroquinone are added therein to continue the reaction, and after determining that the -NCO group content is close to zero, desolvation is carried out by reduced pressure distillation at 60°C and -0.095MPa for 3 hours to obtain the organosilicon-modified polyurethane acrylate prepolymer.

[0038] Furthermore, the R value of the silicone-modified polyurethane acrylate prepolymer reaction system is 1.1, the molar ratio of IPDI, PPG and HEMA is 2.2:1:2, the amino-terminated PDMS accounts for 20% of the total mass of the prepolymer, and the molecular weight of the amino-terminated PDMS is 3000 g / mol.

[0039] Furthermore, the preparation method of the polyether polyurethane acrylate includes the following steps: fully dissolving polypropylene glycol (PPG) in acetone, maintaining a nitrogen atmosphere after evacuation, raising the temperature to 40°C, and adding IPDI and 0.03 wt% of a bismuth-based catalyst to react until the -NCO group content in the system reaches 50% of the theoretical value. Subsequently, the temperature is raised to 70°C, and HPA and p-methylphenyl ether are added to continue the reaction. The infrared spectrum at 2267 cm -1 The disappearance of the characteristic peak of the -NCO group at is considered to be the end of the reaction, and the solvent is removed by vacuum distillation at 60° C. and −0.095 MPa for 3 h to obtain the polyether polyurethane acrylate.

[0040] Furthermore, the PPG is a primary hydroxyl-terminated PPG with a molecular weight of 2000 g / mol and a hydroxyl value of 33 mgKOH / g.

[0041] Furthermore, the blocked isocyanate is ε-caprolactam blocked isocyanate.

[0042] Furthermore, the diluent is compounded by isobornyl acrylate and dipropylene glycol diacrylate in a mass ratio of 1.5:1.

[0043] Furthermore, the pigment is carbon black FW200.

[0044] Furthermore, the photoinitiator is compounded by TPO and 184 in a mass ratio of 2:1, and also includes 0.2 parts of amine accelerator, and the amine accelerator is ammonia-modified acrylate.

[0045] Furthermore, the leveling agent is a fluorine-modified acrylate leveling agent.

[0046] Furthermore, the amino-modified silica is obtained by placing nano-silica in 0.5% silane coupling agent KH-550 and stirring at high speed.

[0047] Furthermore, the one-coat colored dual-curing UV paint also includes 0.8 parts of a weathering additive, which is a compound of an ultraviolet absorber (Tinuvin 384-2) and a hindered amine light stabilizer (Tinuvin 292) in a mass ratio of 1:1.8.

[0048] Furthermore, the one-coat colored dual-curing UV paint also includes 2.5 parts of a modified polypropylene adhesion promoter, and the modified polypropylene adhesion promoter is a chlorinated polyolefin.

[0049] The preparation method of a colored dual-curing UV paint of this embodiment includes the following steps:

[0050] Step S1: mixing the pigment with 30% diluent and grinding the mixture with a grinder to a fineness of less than 5 μm;

[0051] Step S2: stirring the trifunctional aliphatic polyurethane acrylate resin, silicone-modified polyurethane acrylate prepolymer, polyether polyurethane acrylate, and silicone-acrylic hybrid resin in sequence at 25° C. until completely dispersed, and then adding a leveling agent, a weathering agent, and an adhesion promoter according to the formulation requirements;

[0052] Step S3, adding amino-modified silica and the pigment obtained in step S1, and uniformly dispersing them with a high-speed dispersant and the remaining diluent;

[0053] Step S4: adding blocked isocyanate thereto, and then adding photoinitiator under light-proof conditions, adding the remaining diluent dropwise to adjust the viscosity during the reaction, and finally adjusting the system viscosity to 1200 mPa·s, and obtaining the one-coat colored dual-curing UV paint after filtration.

[0054] Furthermore, the curing method of the colored dual-curing UV paint is as follows: spray the obtained UV paint on the cleaned surface of the material, irradiate it with a UV lamp, and then bake it at 85°C for 30 minutes, and then cool it down to complete the curing process. The wavelength of the UV lamp is 365nm, and the power is 80mW / cm 2 , time is 15s.

[0055] Example 2

[0056] This embodiment provides a colored dual-curing UV paint, comprising the following raw materials in parts by weight: 16 parts of trifunctional aliphatic polyurethane acrylate resin, 12 parts of silicone-modified polyurethane acrylate prepolymer, 7 parts of polyether polyurethane acrylate, 10 parts of silicone-acrylic hybrid resin, 6 parts of blocked isocyanate, 17 parts of diluent, 1.8 parts of pigment, 3.5 parts of amino-modified silica, 2 parts of photoinitiator, and 0.15 parts of leveling agent.

[0057] Furthermore, the trifunctional aliphatic polyurethane acrylic resin has an average functionality of 3 and a hydroxyl value of 30 mgKOH / g.

[0058] Furthermore, the preparation method of the organosilicon-modified polyurethane acrylate prepolymer includes the following steps: placing IPDI and acetone in a reactor, maintaining a nitrogen atmosphere after emptying, raising the temperature to 50°C, slowly adding amino-terminated PDMS dropwise therein, and adding 0.03-0.1wt% bismuth-zinc composite catalyst to react for 2-3 hours, then raising the temperature to 60°C, adding PPG therein for chain extension, and detecting that the -NCO group content in the system reaches the theoretical value and no longer decreases, at which point the reaction can be considered to have reached equilibrium. Subsequently, HEMA and 0.05-0.3wt% hydroquinone are added thereto to continue the reaction. After the -NCO group content is determined to be close to zero, the solvent is removed by reduced pressure distillation at 60°C and -0.095MPa for 2-3 hours to obtain the organosilicon-modified polyurethane acrylate prepolymer.

[0059] Furthermore, the R value of the silicone-modified polyurethane acrylate prepolymer reaction system is 1.1, the molar ratio of IPDI, PPG and HEMA is 2.2:1:2, the amino-terminated PDMS accounts for 25% of the total mass of the prepolymer, and the molecular weight of the amino-terminated PDMS is 3000 g / mol.

[0060] Furthermore, the preparation method of the polyether polyurethane acrylate includes the following steps: fully dissolving polypropylene glycol (PPG) in acetone, maintaining a nitrogen atmosphere after evacuation, raising the temperature to 40°C, and adding IPDI and 0.05wt% bismuth-based catalyst to react until the -NCO group content in the system reaches 50% of the theoretical value. Subsequently, the temperature is raised to 70°C, and HPA and p-methylphenyl ether are added to continue the reaction. The infrared spectrum at 2267cm -1 The disappearance of the characteristic peak of the -NCO group at is considered to be the end of the reaction, and the solvent is removed by reduced pressure distillation at 60° C. and −0.095 MPa for 2 h to obtain the polyether polyurethane acrylate.

[0061] Furthermore, the PPG is a primary hydroxyl terminated PPG with a molecular weight of 3000 g / mol and a hydroxyl value of 37.3 mgKOH / g.

[0062] Furthermore, the blocked isocyanate is ε-caprolactam blocked isocyanate.

[0063] Furthermore, the diluent is prepared by compounding isobornyl acrylate and dipropylene glycol diacrylate in a mass ratio of 1.3:1.

[0064] Furthermore, the pigment is Pigment Black 7.

[0065] Furthermore, the photoinitiator is compounded by TPO and 819 in a mass ratio of 1.5:1, and also includes 0.15 parts of amine accelerator, and the amine accelerator is ammonia-modified acrylate.

[0066] Furthermore, the leveling agent is a fluorine-modified acrylate leveling agent.

[0067] Furthermore, the amino-modified silica is obtained by placing nano-silica in 0.5% silane coupling agent KH-550 and stirring at high speed.

[0068] Furthermore, the one-coat colored dual-curing UV paint also includes 1.0 part of a weathering additive, which is compounded by a UV absorber (Tinuvin 384-2) and a hindered amine light stabilizer (Tinuvin 292) in a mass ratio of 1:1.5.

[0069] Furthermore, the one-coat colored dual-curing UV paint also includes 1.8 parts of a modified polypropylene adhesion promoter, and the modified polypropylene adhesion promoter is maleic anhydride grafted polypropylene.

[0070] The preparation method of a colored dual-curing UV paint of this embodiment includes the following steps:

[0071] Step S1: mixing the pigment with 30% diluent and grinding the mixture with a grinder to a fineness of less than 5 μm;

[0072] Step S2: stirring the trifunctional aliphatic polyurethane acrylate resin, the silicone-modified polyurethane acrylate prepolymer, the polyether polyurethane acrylate, and the silicone-acrylic hybrid resin in sequence at 25° C. until completely dispersed, and then adding a leveling agent, a weathering agent, or an adhesion promoter according to the formulation requirements;

[0073] Step S3, adding amino-modified silica and the pigment obtained in step S1, and uniformly dispersing them with a high-speed dispersant and the remaining diluent;

[0074] Step S4: adding blocked isocyanate thereto, and then adding a photoinitiator under light-proof conditions, adjusting the system viscosity to 1200 mPa·s, and obtaining the one-coat colored dual-curing UV paint after filtering.

[0075] Furthermore, the curing method of the colored dual-curing UV paint is as follows: spray the obtained UV paint on the surface of the cleaned material, irradiate it with a UV lamp, and then bake it at 90°C for 25 minutes, and then cool it down to complete. The wavelength of the UV lamp is 350nm and the power is 100mW / cm 2 , time is 12s.

[0076] Example 3

[0077] This embodiment provides a colored dual-curing UV paint, comprising the following raw materials in parts by weight: 20 parts of trifunctional aliphatic polyurethane acrylate resin, 16 parts of silicone-modified polyurethane acrylate prepolymer, 5 parts of polyether polyurethane acrylate, 15 parts of silicone-acrylic hybrid resin, 8 parts of blocked isocyanate, 14 parts of diluent, 2.5 parts of pigment, 5.5 parts of amino-modified silica, 2.8 parts of photoinitiator, and 0.25 parts of leveling agent.

[0078] Furthermore, the trifunctional aliphatic polyurethane acrylic resin has an average functionality of 3 and a hydroxyl value of 30 mgKOH / g.

[0079] Furthermore, the preparation method of the organosilicon-modified polyurethane acrylate prepolymer includes the following steps: placing IPDI and acetone in a reactor, maintaining a nitrogen atmosphere after emptying, raising the temperature to 50°C, slowly adding amino-terminated PDMS dropwise therein, and adding 0.08wt% bismuth-zinc composite catalyst to react for 2 hours, then raising the temperature to 60°C, adding PPG therein for chain extension, and detecting that the -NCO group content in the system reaches the theoretical value and no longer decreases, at which point the reaction can be considered to have reached equilibrium. Subsequently, HEMA and 0.25wt% hydroquinone are added therein to continue the reaction, and after determining that the -NCO group content is close to zero, the solvent is removed by reduced pressure distillation at 60°C and -0.095MPa for 2 hours to obtain the organosilicon-modified polyurethane acrylate prepolymer.

[0080] Furthermore, the R value of the silicone-modified polyurethane acrylate prepolymer reaction system is 1.1, the molar ratio of IPDI, PPG and HEMA is 2.2:1:2, the amino-terminated PDMS accounts for 25% of the total mass of the prepolymer, and the molecular weight of the amino-terminated PDMS is 4000 g / mol.

[0081] Furthermore, the preparation method of the polyether polyurethane acrylate includes the following steps: fully dissolving polypropylene glycol (PPG) in acetone, maintaining a nitrogen atmosphere after evacuation, raising the temperature to 40°C, and adding IPDI and 0.05wt% bismuth-based catalyst to react, and detecting the -NCO group content in the system to reach 80% of the theoretical value. Subsequently, the temperature is raised to 70°C, and HPA and p-methylphenyl ether are added to continue the reaction, and the infrared spectrum is detected at 2267cm -1 The disappearance of the characteristic peak of the -NCO group at is considered to be the end of the reaction, and the solvent is removed by vacuum distillation at 60° C. and −0.095 MPa for 2 h to obtain the polyether polyurethane acrylate.

[0082] Furthermore, the PPG is a primary hydroxyl terminated PPG with a molecular weight of 4000 g / mol and a hydroxyl value of 56 mgKOH / g.

[0083] Furthermore, the blocked isocyanate is ε-caprolactam blocked isocyanate.

[0084] Furthermore, the diluent is compounded by isobornyl acrylate and dipropylene glycol diacrylate in a mass ratio of 1.5:1.

[0085] Furthermore, the pigment is carbon black FW200.

[0086] Furthermore, the photoinitiator is compounded by 819 and 184 in a mass ratio of 1.8:1, and further comprises 0.3 parts of an amine accelerator, which is an ammonia-modified acrylate.

[0087] Furthermore, the leveling agent is a fluorine-modified acrylate leveling agent.

[0088] Furthermore, the amino-modified silica is obtained by placing nano-silica in 0.5% silane coupling agent KH-550 and stirring at high speed.

[0089] Furthermore, the one-coat colored dual-curing UV paint also includes 1.0 part of a weathering additive, which is compounded by a UV absorber (Tinuvin 384-2) and a hindered amine light stabilizer (Tinuvin 292) in a mass ratio of 1:2.

[0090] Furthermore, the one-coat colored dual-curing UV paint also includes 3 parts of a modified polypropylene adhesion promoter, and the modified polypropylene adhesion promoter is a chlorinated polyolefin.

[0091] The preparation method of a colored dual-curing UV paint of this embodiment includes the following steps:

[0092] Step S1: mixing the pigment with 30% diluent and grinding the mixture with a grinder to a fineness of less than 5 μm;

[0093] Step S2: stirring the trifunctional aliphatic polyurethane acrylate resin, the silicone-modified polyurethane acrylate prepolymer, the polyether polyurethane acrylate, and the silicone-acrylic hybrid resin in sequence at 30° C. until completely dispersed, and then adding a leveling agent, a weathering agent, or an adhesion promoter according to the formulation requirements;

[0094] Step S3, adding amino-modified silica and the pigment obtained in step S1, and uniformly dispersing them with a high-speed dispersant and the remaining diluent;

[0095] Step S4: adding blocked isocyanate thereto, and then adding a photoinitiator under light-proof conditions, adjusting the system viscosity to 1100 mPa·s, and obtaining the one-coat colored dual-curing UV paint after filtering.

[0096] Furthermore, the curing method of the colored dual-curing UV paint is as follows: spraying the obtained UV paint on the surface of the cleaned material, irradiating it with a UV lamp, and then baking it at 100°C for 25 minutes, and then cooling it to complete the process. The wavelength of the UV lamp is 365nm, and the power is 100mW / cm 2 , time is 10s.

[0097] Comparative Example 1

[0098] The difference between this comparative example and Example 1 is that the organosilicon-modified polyurethane acrylate prepolymer in Example 1 is not added to this comparative example, and the remaining components are adjusted in equal proportions.

[0099] Comparative Example 2

[0100] The difference between this comparative example and Example 1 is that the polyether polyurethane acrylate in Example 1 is not added in this comparative example, and the remaining components are adjusted in equal proportions.

[0101] Comparative Example 3

[0102] The difference between this comparative example and Example 1 is that the organosilicon-acrylic hybrid resin in Example 1 is not added in this comparative example, and the remaining components are adjusted in equal proportions.

[0103] Comparative Example 4

[0104] The difference between this comparative example and Example 1 is that this comparative example uses nano-silica instead of amino-modified silica, and the diluent is isobornyl acrylate.

[0105] The present invention performs performance tests on the colored dual-curing UV paint prepared by Examples 1-3 and Comparative Examples 1-4, wherein the material is PP and the coating thickness is 30 μm. The adhesion is tested in accordance with ISO 2409-2020. The wear resistance is tested in accordance with GB / T 1768-2006, using a rubber grinding wheel CS-10 with a load of 500 g and a rotation speed of 60 rpm. The scratch resistance is tested in accordance with GB / T 6739-2006. The UV aging resistance is tested in accordance with the fluorescent UV lamp in GB / T 16422.3-2014, using a UVB-313 lamp with a light intensity of 0.71 W / m 2 , temperature 60°C, humidity 50%, cycle test for 1000h; when the treated sample's ΔE ≤ 2 (no obvious discoloration), adhesion still maintains level 0-1, and hardness retention rate ≥ 90%, it is considered qualified. Solvent abrasion resistance is tested according to Method B in GB / T 23989-2009. Use a cotton cloth dipped in 75% ethanol and wipe back and forth 50 times under a load of 500g to observe whether the coating loses gloss, changes color, or exposes the bottom. If there is no loss of gloss or exposure, it is considered qualified. Hydrolysis resistance: The hydrolysis resistance of UV paint and materials is tested according to GB / T 1733-1993 standard in an environment of 90°C and 90% RH for 72h. If the test results show a grayscale level ≥ Level 4 and adhesion ≤ Level 2, it is considered qualified.

[0106] The specific test results are shown in the following table.

[0107]

[0108]

[0109] As can be seen from the data in the table above, the one-coat, dual-cured UV paint prepared in Examples 1-3 achieves significant improvements in adhesion, wear resistance, weather resistance, and hydrolysis resistance through the synergistic combination of multiple resins, including trifunctional aliphatic polyurethane acrylic resin, silicone-modified polyurethane acrylate prepolymer, polyether polyurethane acrylate, and silicone-acrylic hybrid resin. Among them, the trifunctional aliphatic polyurethane acrylic resin and amino-modified silica jointly improve the hardness and scratch resistance of the UV paint; the silicone-modified polyurethane acrylate prepolymer provides good flexibility and wear resistance; the polyether polyurethane acrylate imparts good flexibility and water resistance to the UV paint; and the silicone-acrylic hybrid resin enhances the adhesion of the UV paint. Furthermore, the dual-curing mechanism of a combination of UV curing and thermal curing improves production efficiency while ensuring the complete curing and durability of the UV paint.

[0110] Furthermore, the VOCs content of the UV paints prepared in Examples 1-3 of the present invention was tested according to GB / T 27630-2011, and the results showed that the VOCs content was less than 40 g / L, indicating that the UV paints met the low VOCs environmental protection requirements.

[0111] The above specific embodiments are further explanations of the technical solutions and beneficial effects of the present invention, and are not intended to limit the implementation methods. For those skilled in the art, any obvious substitutions that do not depart from the concept of the present invention are within the scope of protection of the present invention.

Claims

1. One-coat colored dual-curing UV paint, characterized by: The invention comprises the following raw materials in parts by weight: 15-20 parts of trifunctional aliphatic polyurethane acrylic resin, 12-16 parts of silicone modified polyurethane acrylate prepolymer, 5-8 parts of polyether polyurethane acrylate, 10-15 parts of silicone-acrylic hybrid resin, 4-9 parts of blocked isocyanate, 15-25 parts of diluent, 1-3 parts of pigment, 3-6 parts of amino modified silica, 1-3 parts of photoinitiator and 0.1-0.3 parts of leveling agent.

2. The one-coat colored dual-curing UV paint according to claim 1, characterized in that: The blocked isocyanate is ε-caprolactam blocked isocyanate.

3. The one-coat colored dual-curing UV paint according to claim 2, characterized in that: The diluent is at least one of dipropylene glycol diacrylate (DPGDA), isodecyl acrylate IDA, and isosorbide acrylate IBOA.

4. The one-coat colored dual-curing UV paint according to claim 1, characterized in that: The pigment is preferably a carbon black paste.

5. The one-coat colored dual-curing UV paint according to claim 1, characterized in that: The photoinitiator is at least one of TPO, 819, and 184.

6. The one-coat colored dual-curing UV paint according to claim 1, characterized in that: The leveling agent is a fluorine-modified acrylate leveling agent.

7. The one-coat colored dual-curing UV paint according to claim 1, characterized in that: The one-coat colored dual-curing UV paint also includes 0.8-1.2 parts of a weathering additive, which is a combination of one or more of an ultraviolet absorber, a hindered amine light stabilizer, and an antioxidant.

8. The one-coat colored dual-curing UV paint according to claim 1, characterized in that: The one-coat colored dual-curing UV paint also includes 0.5-3 parts of a modified polypropylene adhesion promoter, wherein the modified polypropylene adhesion promoter is at least one of chlorinated polyolefin, maleic anhydride grafted polypropylene or phosphate modified acrylate.

9. The method for producing a colored dual-curing UV paint according to any one of claims 1 to 8, characterized in that: The steps include: Step S1: mixing the pigment with a portion of the diluent, and grinding the mixture with a grinder to a fineness of less than 5 μm; Step S2: stirring the trifunctional aliphatic polyurethane acrylate resin, the silicone-modified polyurethane acrylate prepolymer, the polyether polyurethane acrylate, and the silicone-acrylic hybrid resin in sequence at 25-30° C. until completely dispersed, and then adding a leveling agent, a weathering agent, or an adhesion promoter according to the formulation requirements; Step S3, adding amino-modified silica and the pigment obtained in step S1, and uniformly dispersing them with a high-speed dispersant and the remaining diluent; Step S4: adding blocked isocyanate thereto, and then adding a photoinitiator under light-proof conditions, adjusting the system viscosity to 1000-1200 mPa·s, and obtaining the one-coat colored dual-curing UV paint after filtering.

10. The method for preparing a colored dual-curing UV paint according to claim 9, characterized in that: In step S4, the curing process is specifically: irradiation with UV lamp, and then baking at 80-100°C for 20-30 minutes. The wavelength of the UV lamp is 300-400nm, and the power is 80-120mW / cm 2 , time is 10-15s.

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