Solvent-resistant, scratch-resistant, and invisible car paint and its preparation method

Abstract

The application relates to a solvent-resistant and scratch-resistant invisible car paint and a preparation method thereof, and relates to the technical field of automobile protection materials, and comprises a protective film, a UV curing coating, an intermediate functional layer, a transparent substrate layer, a glue layer and a release film, the UV curing coating is obtained by coating UV curing paint, and the preparation raw materials of the UV curing paint comprise the following components in mass fraction: 50-70 parts of polyurethane prepolymer, 20-30 parts of silicone-modified epoxy acrylate, 5-15 parts of modified zirconium phosphate nanosheet chain extender, 1-3 parts of composite photoinitiator, 1-3 parts of light stabilizer, 0.5-1 part of antioxidant and 20-30 parts of solvent. The application has the effect of improving the solvent resistance and scratch resistance of the invisible car paint, the car paint can effectively resist the impact of external force, and good working performance can be maintained for a long time.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of automobile protective materials, in particular to a solvent-resistant and scratch-resistant invisible car paint and a preparation method thereof. BACKGROUND

[0002] In recent years, invisible car paint, as an important automobile protection product, has been widely used and developed. Invisible car paint not only effectively prevents scratches and UV damage, but also enhances the overall aesthetic appearance of the vehicle. With the rapid development of the automobile market and technological progress, consumers have increasingly high requirements for invisible car paint, especially the demand for its solvent resistance and scratch resistance. In order to meet market demand, many enterprises have invested a large amount of resources in technological research and development, promoting continuous innovation and improvement in this field.

[0003] Currently, in the field of invisible car paint, common technical means mainly include the use of different types of substrate layers and functional coatings. For example, some manufacturers use TPU (thermoplastic polyurethane) film as the substrate layer because it has good elasticity and tear resistance; while others choose PVC (polyvinyl chloride) or other synthetic materials. In terms of functional coatings, commonly used materials include ordinary polyurethane resin, epoxy resin, etc., and various additives are added to improve their specific properties. In addition, some enterprises introduce nanomaterials into the coating to enhance the wear resistance and chemical stability of the coating. These conventional means can improve the performance of invisible car paint to some extent, but still have certain limitations.

[0004] However, existing invisible car paint still faces many challenges in actual application. Especially when facing strong solvent erosion and sharp object scratching, traditional invisible car paint is often prone to damage or loss of protective effect. These problems not only reduce the service life of the product, but also affect user experience, so improvement is needed. SUMMARY

[0005] In order to improve the solvent resistance and scratch resistance of invisible car paint, the application provides a solvent-resistant and scratch-resistant invisible car paint and a preparation method thereof.

[0006] The solvent-resistant and scratch-resistant invisible car paint and the preparation method thereof provided by the application adopt the following technical solutions: in a first aspect, the solvent-resistant and scratch-resistant invisible car paint provided by the application adopts the following technical solutions:

[0007] A solvent-resistant and scratch-resistant invisible car paint, comprising a protective film, a UV cured coating, an intermediate functional layer, a transparent substrate layer, a glue layer, and a release film, wherein the UV cured coating is obtained by coating UV cured paint, and the preparation raw materials of the UV cured paint include the following components in mass fraction:

[0008] Polyurethane prepolymer 50-70 parts

[0009] Silicone-modified epoxy acrylate 20-30 parts

[0010] Modified zirconium phosphate nanosheet chain extender 5-15 parts

[0011] Composite photoinitiator 1-3 parts

[0012] Light stabilizer 1-3 parts

[0013] Antioxidant 0.5-1 part

[0014] Solvent 20-30 parts.

[0015] The polyurethane prepolymer has good flexibility and mechanical strength, and when subjected to scratching, the molecular structure can effectively buffer and disperse external force, reducing the damage to the coating; the silicone in the silicone-modified epoxy acrylate gives the coating excellent weather resistance and low surface energy, inhibiting stain contamination, and the epoxy acrylate enhances the hardness and chemical stability of the coating through photocuring crosslinking reaction, and enhances the resistance to solvents; the modified zirconium phosphate nanosheet chain extender, with its unique nanostructure, plays the role of a "molecular bridge" in the system, connecting molecular chains, increasing crosslinking density, and improving overall strength and toughness; the composite photoinitiator rapidly initiates polymerization under light, promoting the construction of a stable three-dimensional network structure by each component; the light stabilizer can absorb ultraviolet light, improving the anti-aging performance of the coating and prolonging the service life of the car paint; the synergistic effect of each component improves the solvent resistance and scratch resistance of the invisible car paint.

[0016] Preferably, the raw materials for preparing the polyurethane prepolymer include naphthalene diisocyanate and bisphenol S.

[0017] Naphthalene diisocyanate contains a naphthalene ring, has a highly conjugated and rigid aromatic structure, and bisphenol S molecules contain two benzene rings connected by a sulfone group. When synthesizing the polyurethane prepolymer, stable urethane bonds are formed, and rigid groups are introduced into the molecular chain, making the formed polymer molecular chain have high rigidity; the rigid molecular chain can effectively resist the action of external force, and form a tightly crosslinked network during curing, enhancing the structural strength and reducing the deformation of the coating when subjected to scratching, thereby significantly improving the hardness and scratch resistance of the coating; the sulfone group of bisphenol S has high chemical stability, can effectively resist the erosion of solvent molecules, prevent their penetration, and maintain the integrity of the coating structure, thereby improving the solvent resistance and scratch resistance of the invisible car paint.

[0018] Preferably, the raw materials for preparing the silicone-modified epoxy acrylate include epoxy acrylate and dodecafluoroheptylpropyltrimethoxysilane.

[0019] The epoxy acrylate contains a benzene ring and an active double bond that can participate in the reaction, giving the polymer rigidity and good curing characteristics; the dodecafluoroheptyl propyl trimethoxysilane contains a long carbon chain fluorine-containing group and a silanol group, which hydrolyzes to form a silanol during the reaction, and then condenses with the hydroxyl group or other active groups in the epoxy acrylate, introducing a fluorine-containing silane segment into the epoxy acrylate molecule; the fluorine-containing long carbon chain greatly reduces the surface energy of the coating by virtue of low surface energy and steric hindrance effect, making it difficult for solvents to adhere and penetrate, thereby improving the solvent resistance; the fluorine-containing long carbon chain also enhances the flexibility of the coating, combined with the cross-linked structure formed by the curing of the epoxy acrylate, effectively resisting external forces during scratching, and improving the scratch resistance; at the same time, the dense protective film formed by the long carbon chain fluorine-containing silane enhances the chemical stability and wear resistance, making the coating have better comprehensive performance.

[0020] Preferably, the mass ratio of the epoxy acrylate and the dodecafluoroheptyl propyl trimethoxysilane is 1:(0.1-0.3).

[0021] The organic silicon-modified epoxy acrylate prepared according to the above mass ratio has good reactivity, can effectively reduce the surface energy of the UV-cured coating, and improve the solvent resistance and scratch resistance of the stealth car paint.

[0022] Preferably, the raw materials for preparing the modified zirconium phosphate nanosheet chain extender include hydroxylated zirconium phosphate nanosheets and amino silane coupling agents.

[0023] The surface of the hydroxylated zirconium phosphate nanosheet is rich in hydroxyl groups, the alkoxyl group at one end of the amino silane coupling agent can undergo condensation reaction with these hydroxyl groups, realizing chemical bonding of the two, and the amino group at the other end provides active sites for subsequent reactions; the introduction of this chain extender into the polymer system of the stealth car paint can effectively improve the solvent resistance, the chemical bond between the chain extender and the polymer molecules enhances the intermolecular forces, improves the cohesion and toughness of the coating, and reinforces the defects of the molecular chain, thereby better resisting external forces during scratching and effectively improving the scratch resistance; the amino silane coupling agent can also improve the compatibility of the nanosheet with the polymer matrix, making the nanosheet uniformly dispersed in the system and further exerting its reinforcing effect, so that the stealth car paint can better meet the actual use requirements.

[0024] Preferably, the modified zirconium phosphate nanosheet chain extender is prepared by the following steps:

[0025] The zirconium phosphate nanosheet is dispersed in a dilute hydrochloric acid solution to obtain a nanosheet dispersion; the nanosheet dispersion is subjected to water bath stirring reaction, cooled after the reaction is completed, centrifuged to discard the supernatant, washed and dried the precipitate to obtain hydroxylated zirconium phosphate nanosheets;

[0026] The hydroxylated zirconium phosphate nanosheet is dispersed in toluene, and a dispersion liquid is obtained after ultrasonic treatment; the amino silane coupling agent is added to the nanosheet dispersion liquid, and heated and stirred to reflux for reaction; after the reaction is completed, the mixture is cooled, washed and dried to obtain the modified zirconium phosphate nanosheet chain extender.

[0027] The modified zirconium phosphate nanosheet chain extender prepared according to the above steps has good dispersibility and reactivity, and can effectively reinforce the UV-cured coating and improve the solvent resistance and scratch resistance of the stealth car paint.

[0028] Preferably, the composite photoinitiator comprises 1-hydroxycyclohexyl phenyl ketone and bis(4-tert-butylphenyl) iodonium tetraphenylborate.

[0029] 1-hydroxycyclohexyl phenyl ketone is a cleavage type free radical photoinitiator, which rapidly cleaves to generate free radicals after absorbing UV light, and can efficiently initiate the free radical polymerization of acrylate monomers in the system to rapidly form a preliminary polymer network structure; bis(4-tert-butylphenyl) iodonium tetraphenylborate is a cationic photoinitiator, which generates a proton acid under the action of UV light to initiate the cationic polymerization of epoxy monomers in the system; the two polymerization mechanisms synergize with each other, the free radical polymerization rapidly lays the foundation for the network, and the cationic polymerization further fills and perfects the network structure, greatly increasing the crosslinking density of the system; this efficient crosslinking increases the hardness and wear resistance of the UV-cured coating, and enables the coating to better resist scratches; at the same time, the dense crosslinked structure also effectively prevents the penetration of solvent molecules, significantly improving the solvent resistance, so that the stealth car paint can better protect the vehicle paint and prolong the service life in actual use.

[0030] Preferably, the preparation raw materials of the intermediate functional layer comprise polyurethane elastomer, ethylene-vinyl acetate copolymer and nanoclay.

[0031] The soft segment in the molecular structure of the polyurethane elastomer endows it with good flexibility, which enables the intermediate functional layer to closely adhere to the complex curved surface of the vehicle body, and the hard segment provides strength to maintain the stability of the structure during vehicle vibration; the ethylene-vinyl acetate copolymer further enhances the overall flexibility due to its excellent flexibility and low temperature resistance, and its good adhesion can improve the adhesion between layers; the nanoclay has high modulus and lamellar structure, and is uniformly dispersed in the system, the sliding between the lamellae can absorb energy to improve the puncture resistance, and at the same time, the tortuous path formed by the lamellae can effectively block gas and liquid molecules to improve the solvent resistance; the synergistic effect of the three provides stable support for the stealth car paint, enhances the impact resistance and puncture resistance, improves the solvent resistance, prolongs the service life, and thus improves the protection effect on the vehicle paint.

[0032] Preferably, the mass ratio of the polyurethane elastomer, ethylene-vinyl acetate copolymer and nanoclay is 1:0.4:(0.1-0.2).

[0033] The intermediate functional layer prepared according to the mass ratio can effectively improve the puncture resistance and solvent resistance of the invisible car paint.

[0034] In a second aspect, the application provides a preparation method of a solvent-resistant and scratch-resistant invisible car paint, which adopts the following technical scheme:

[0035] The preparation method of the solvent-resistant and scratch-resistant invisible car paint comprises the following steps:

[0036] The polyurethane prepolymer, the silicone-modified epoxy acrylate, and the modified zirconium phosphate nanosheet chain extender are dispersed into a solvent, and after stirring and mixing, a composite photoinitiator, a light stabilizer, and an antioxidant are added and stirred and mixed, to obtain a UV curing coating;

[0037] The UV curing coating is coated onto the surface of the intermediate functional layer, and after UV curing, an intermediate material layer with a UV curing coating is obtained; the intermediate material layer with the UV curing coating is hot-pressed and attached to the transparent substrate layer away from the UV curing coating, a pressure-sensitive adhesive is uniformly coated on the other surface of the well-attached transparent substrate layer, to obtain an adhesive layer, a release film is overlaid on the adhesive layer and rolled, a protective film is overlaid on the surface of the UV curing coating, to obtain the solvent-resistant and scratch-resistant invisible car paint.

[0038] The invisible car paint prepared according to the above steps has good solvent resistance and scratch resistance, and can effectively resist external force impact and maintain good working performance for a long time.

[0039] In summary, the application has at least one of the following beneficial technical effects:

[0040] 1. The polyurethane prepolymer has good flexibility and mechanical strength, and when scratched, the molecular structure can effectively buffer and disperse external force, reducing damage to the coating; the organic silicon in the silicone-modified epoxy acrylate gives the coating excellent weather resistance and low surface energy, inhibiting stain contamination, and the epoxy acrylate enhances the hardness and chemical stability of the coating through photocuring crosslinking reaction, and enhances the resistance to solvents; the modified zirconium phosphate nanosheet chain extender plays a "molecular bridge" role in the system due to its unique nanostructure, connecting molecular chains, increasing crosslinking density, and improving overall strength and toughness; the composite photoinitiator rapidly initiates polymerization under light, promoting the construction of a stable three-dimensional network structure by each component; the light stabilizer can absorb ultraviolet rays, improving the anti-aging performance of the coating and prolonging the service life of the car paint; the synergistic effect of each component improves the solvent resistance and scratch resistance of the invisible car paint.

[0041] 2. The epoxy acrylate contains a benzene ring and a reactive double bond that can participate in the reaction, giving the polymer rigidity and good curing characteristics; the dodecafluoroheptylpropyltrimethoxysilane contains a long carbon chain fluorine-containing group and a silanol group, which hydrolyzes to form a silanol during the reaction, and then condenses with the hydroxyl group or other active groups in the epoxy acrylate, introducing a fluorine-containing silane chain segment into the epoxy acrylate molecule; the fluorine-containing long carbon chain greatly reduces the surface energy of the coating by virtue of low surface energy and steric hindrance effect, making it difficult for solvents to adhere and penetrate, improving solvent resistance; the fluorine-containing long carbon chain also enhances the flexibility of the coating, combined with the cross-linked structure formed by the curing of the epoxy acrylate, effectively resisting external forces during scratching, and improving the scratch resistance; at the same time, the dense protective film formed by the long carbon chain fluorine-containing silane enhances the chemical stability and wear resistance, making the coating have better comprehensive performance.

[0042] 3. The hydroxylated zirconium phosphate nanosheet is rich in hydroxyl groups on the surface, and the alkoxy group on one end of the amino silane coupling agent can undergo condensation reaction with these hydroxyl groups, realizing chemical bonding of the two, and the amino group on the other end provides active sites for subsequent reactions; introducing this chain extender into the polymer system of the invisible car paint, the two-dimensional sheet structure of the nanosheet can physically block the penetration of solvent molecules, significantly improving the solvent resistance; the chemical bond formed between the chain extender and the polymer molecules enhances the intermolecular forces, improving the cohesion and toughness of the coating, reinforcing the defects of the molecular chain, and better resisting external forces when scratched, effectively improving the scratch resistance; the amino silane coupling agent can also improve the compatibility of the nanosheet with the polymer matrix, making the nanosheet uniformly dispersed in the system, further playing its reinforcing role, so that the invisible car paint can better meet the actual use requirements. DETAILED DESCRIPTION

[0043] The application discloses a solvent-resistant and scratch-resistant invisible car paint and a preparation method thereof. The raw materials used in the application can be obtained through commercial raw materials, except for special instructions. The application is further described in detail in combination with the following examples:

[0044] Raw material description: Naphthalene diisocyanate (CAS No. 3173-72-6), Bisphenol S (CAS No. 80-09-1), epoxy acrylate type Zannan EBECRYL 605 / 20, dodecafluoroheptylpropyltrimethoxysilane (CAS No. 1105578-57-1), dibutyltin dilaurate (CAS No. 77-58-7), zirconium phosphate nanosheet purchased from Fujian Ruixin New Material Co., Ltd., amino silane coupling agent is N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane (CAS No. 1760-24-3), polyurethane elastomer type Desmopan 786E / S, ethylene-vinyl acetate copolymer (CAS No. 24937-78-8), nanoclay (CAS No. 1302-78-9), 1-hydroxycyclohexyl phenyl ketone (CAS No. 947-19-3), bis(4-tert-butylphenyl) iodonium tetraphenylborate (CAS No. 131725-16-1), light stabilizer type Antioxidant type Antioxidant 1010, toluene diisocyanate (CAS No. 26471-62-5), bisphenol A (CAS No. 80-05-7), methyltrimethoxysilane (CAS No. 1185-55-3).

[0045] Example 1

[0046] Preparation of polyurethane prepolymer

[0047] Under the protection of nitrogen, 62.7 kg of naphthalene diisocyanate was warmed to 60°C, and an acetone solution containing 37.3 kg of bisphenol S (mass concentration of 33.33%) was added to the naphthalene diisocyanate, which was added within 30 min. After the addition was completed, the reaction was stirred at 80°C at a speed of 200 rpm for 3 h. After the reaction was completed, it was cooled to below 30°C, and the solvent was removed by distillation under reduced pressure to obtain the polyurethane prepolymer.

[0048] Preparation of silicone-modified epoxy acrylate

[0049] 45.45 kg of epoxy acrylate was warmed to 70°C under oil bath conditions and stirred at a speed of 200 rpm, 4.55 kg of dodecafluoroheptylpropyltrimethoxysilane was added, which was added within 2 h, 0.5 kg of dibutyltin dilaurate was added, and the temperature was warmed to 90°C and stirred at a speed of 300 rpm for 4 h. After the reaction was completed, it was cooled to below 30°C, diluted with ethyl acetate, transferred to a separatory funnel and washed with deionized water, the organic phase was separated and dried with anhydrous magnesium sulfate, and the solvent was removed by distillation under reduced pressure to obtain the silicone-modified epoxy acrylate.

[0050] Preparation of modified zirconium phosphate nanosheet chain extender

[0051] 20 kg of zirconium phosphate nanosheets were dispersed in 100 L of 0.1 mol / L dilute hydrochloric acid solution to obtain a nanosheet dispersion. The nanosheet dispersion was stirred at 200 rpm for 4 h in a 60 °C water bath. After the reaction was completed, the mixture was cooled to below 30 °C, centrifuged to discard the supernatant, and the precipitate was washed with deionized water until the pH value was neutral. The washed precipitate was dried at 60 °C to obtain hydroxylated zirconium phosphate nanosheets.

[0052] The hydroxylated zirconium phosphate nanosheets prepared above were dispersed in 100 L of toluene and sonicated for 15 min to obtain a dispersion. 3 kg of N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane was added to the nanosheet dispersion, heated to 80 °C, stirred continuously at 200 rpm and refluxed for 4 h. After the reaction was completed, the mixture was cooled to below 30 °C, washed with deionized water by centrifugation, and dried at 60 °C to obtain the modified zirconium phosphate nanosheet chain extender.

[0053] Preparation of solvent-resistant and scratch-resistant paint protection film for automobiles

[0054] 66.67 kg of polyurethane elastomer, 26.67 kg of ethylene-vinyl acetate copolymer and 6.66 kg of nano clay were stirred at 1000 rpm for 20 min and added to a twin-screw extruder. The mixture was then extruded at 160°C and 200 rpm to form a sheet with a thickness of 0.1 mm to obtain the intermediate functional layer.

[0055] 50 kg of polyurethane prepolymer, 20 kg of silicone-modified epoxy acrylate, and 5 kg of modified zirconium phosphate nanosheet chain extender were dispersed in 20 kg of ethyl acetate and stirred at 100 rpm for 10 min. Then, 1 kg of composite photoinitiator, 1 kg of light stabilizer, and 0.5 kg of antioxidant were added. The mass ratio of 1-hydroxycyclohexylphenyl ketone and bis(4-tert-butylphenyl)iodonium tetraphenylborate in the photoinitiator was 1:2. The mixture was stirred at 200 rpm for 30 min to obtain a UV-curable coating.

[0056] A UV-curable coating was applied to the surface of the intermediate functional layer with a thickness of 0.1 mm, and then cured under 365 nm ultraviolet light and 1000 mV / cm. 2 Curing under irradiation intensity for 3 minutes yields an intermediate material layer with a UV-curable coating. The side of the intermediate material layer with the UV-curable coating away from the UV-curable coating is hot-pressed onto the transparent substrate layer and bonded at 80°C and 0.5MPa pressure for 2-3 minutes. A 0.05mm thick pressure-sensitive adhesive is then evenly coated onto the other surface of the bonded transparent substrate layer using a gravure coating to obtain an adhesive layer. A release film is then placed on the adhesive layer and rolled. Finally, a protective film is applied to the UV-curable coating to obtain a solvent-resistant and scratch-resistant invisible car wrap.

[0057] Example 2

[0058] Preparation of polyurethane prepolymer

[0059] Under the protection of nitrogen, 62.7 kg of naphthalene diisocyanate was warmed to 60°C, and an acetone solution containing 37.3 kg of bisphenol S (mass concentration of 33.33%) was added to the naphthalene diisocyanate, which was added within 30 min. After the addition was completed, the reaction was stirred at 80°C at a speed of 200 rpm for 3 h. After the reaction was completed, it was cooled to below 30°C, and the solvent was removed by distillation under reduced pressure to obtain the polyurethane prepolymer.

[0060] Preparation of silicone-modified epoxy acrylate

[0061] 38.46 kg of epoxy acrylate was warmed to 70°C under oil bath conditions and stirred at a speed of 200 rpm. 11.54 kg of dodecafluoroheptylpropyltrimethoxysilane was added within 2 h. 0.5 kg of dibutyltin dilaurate was added, and the reaction was stirred at a speed of 300 rpm at 90°C for 4 h. After the reaction was completed, it was cooled to below 30°C, diluted with ethyl acetate, transferred to a separatory funnel, washed with deionized water, and the organic phase was separated and dried with anhydrous magnesium sulfate. The solvent was removed by distillation under reduced pressure to obtain the silicone-modified epoxy acrylate.

[0062] Preparation of modified zirconium phosphate nanosheet chain extender

[0063] 20 kg of zirconium phosphate nanosheets were dispersed in 100 L of 0.1 mol / L dilute hydrochloric acid solution to obtain a nanosheet dispersion. The nanosheet dispersion was stirred at a speed of 200 rpm at 60°C for 4 h. After the reaction was completed, it was cooled to below 30°C, centrifuged, and the supernatant was discarded. The precipitate was washed with deionized water until the pH value was neutral. The washed precipitate was dried at 60°C to obtain hydroxylated zirconium phosphate nanosheets.

[0064] The hydroxylated zirconium phosphate nanosheets prepared above were dispersed in 100 L of toluene, and after ultrasonic treatment for 15 min, a dispersion was obtained. 3 kg of N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane was added to the nanosheet dispersion, heated to 80°C, and continuously stirred at a speed of 200 rpm and refluxed for 4 h. After the reaction was completed, it was cooled to below 30°C, washed with deionized water by centrifugation, and dried at 60°C to obtain the modified zirconium phosphate nanosheet chain extender.

[0065] Preparation of solvent-resistant and scratch-resistant stealth car paint

[0066] The 62.5 kg polyurethane elastomer, 25 kg ethylene-vinyl acetate copolymer and 12.5 kg nanoclay are stirred at a speed of 1000 rpm for 20 min, and then added to a twin-screw extruder to form a sheet with a thickness of 0.1 mm at 160°C and a rotation speed of 200 rpm, thereby obtaining an intermediate functional layer;

[0067] The 70 kg polyurethane prepolymer, 30 kg silicone-modified epoxy acrylate, and 15 kg modified zirconium phosphate nanosheet chain extender are dispersed in 30 kg ethyl acetate, stirred at a speed of 100 rpm for 10 min, and then 3 kg of composite photoinitiator, 3 kg of light stabilizer, and 1 kg of antioxidant are added. The mass ratio of 1-hydroxycyclohexyl phenyl ketone and bis(4-tert-butylphenyl) iodonium tetraphenylborate in the photoinitiator is 1:2. Stirring is performed at a speed of 200 rpm for 30 min to obtain a UV curing coating;

[0068] The UV curing coating is applied to the surface of the intermediate functional layer with a coating thickness of 0.1 mm, and is cured under 365 nm ultraviolet light at an irradiation intensity of 1000 mV / cm2for 3 min to obtain an intermediate material layer with a UV cured coating. The intermediate material layer with the UV cured coating is hot-pressed and attached to the transparent substrate layer away from the UV cured coating at 80°C and a pressure of 0.5 MPa for 2-3 min. A 0.05 mm thick pressure-sensitive adhesive is uniformly coated on the other surface of the attached transparent substrate layer using a gravure coating. A release film is overlaid on the adhesive layer and rolled, and a protective film is overlaid on the UV cured coating to obtain a solvent-resistant and scratch-resistant stealth car paint.

[0069] Example 3

[0070] Preparation of polyurethane prepolymer

[0071] Under nitrogen protection, 62.7 kg of naphthalene diisocyanate is warmed to 60°C, and an acetone solution containing 37.3 kg of bisphenol S (mass concentration of 33.33%) is added to the naphthalene diisocyanate. The addition is completed within 30 min. After the addition is completed, the reaction is stirred at a speed of 200 rpm at 80°C for 3 h. After the reaction is completed, the temperature is cooled to below 30°C, and the solvent is removed by distillation under reduced pressure to obtain a polyurethane prepolymer.

[0072] Preparation of silicone-modified epoxy acrylate

[0073] Heat 41.67 kg of epoxy acrylate to 70°C under oil bath condition and stir at a speed of 200 rpm, add 8.33 kg of dodecafluoroheptyl propyl trimethoxysilane, add in 2 h, add 0.5 kg of dibutyl tin dilaurate, heat to 90°C, stir at a speed of 300 rpm for 4 h, after the reaction is completed, cool to below 30°C, add ethyl acetate for dilution, transfer to a separatory funnel, wash with deionized water, separate the organic phase and dry with anhydrous magnesium sulfate, remove the solvent by distillation under reduced pressure, to obtain a silicone-modified epoxy acrylate.

[0074] Preparation of modified zirconium phosphate nanosheet chain extender

[0075] Disperse 20 kg of zirconium phosphate nanosheet into 100 L of 0.1 mol / L dilute hydrochloric acid solution to obtain a nanosheet dispersion; stir the nanosheet dispersion at 200 rpm for 4 h under a 60°C water bath condition, after the reaction is completed, cool to below 30°C, centrifuge and discard the supernatant, wash the precipitate with deionized water until the pH value is neutral, dry the washed precipitate at 60°C to obtain hydroxylated zirconium phosphate nanosheet.

[0076] Disperse the above-prepared hydroxylated zirconium phosphate nanosheet in 100 L of toluene, after ultrasonic treatment for 15 min, obtain a dispersion; add 3 kg of N-(β-aminoethyl)-γ-aminopropyl trimethoxysilane to the nanosheet dispersion, heat to 80°C, continuously stir at a speed of 200 rpm and reflux for 4 h, after the reaction is completed, cool to below 30°C, wash with deionized water by centrifugation, and dry at 60°C to obtain a modified zirconium phosphate nanosheet chain extender.

[0077] Preparation of solvent-resistant and scratch-resistant stealth car paint

[0078] Stir 64.52 kg of polyurethane elastomer, 25.81 kg of ethylene-vinyl acetate copolymer and 9.67 kg of nanoclay at a speed of 1000 rpm for 20 min, add to a twin-screw extruder, extrude into a sheet with a thickness of 0.1 mm at 160°C and a speed of 200 rpm, to obtain an intermediate functional layer;

[0079] Disperse 60 kg of polyurethane prepolymer, 25 kg of silicone-modified epoxy acrylate, 10 kg of modified zirconium phosphate nanosheet chain extender into 25 kg of ethyl acetate, stir and mix at a speed of 100 rpm for 10 min, add 2 kg of composite photoinitiator, 2 kg of light stabilizer and 0.75 kg of antioxidant, the mass ratio of 1-hydroxycyclohexyl phenyl ketone and bis(4-tert-butylphenyl) iodonium tetraphenylborate in the photoinitiator is 1:2, stir and mix at a speed of 200 rpm for 30 min to obtain a UV curing coating; coat the UV curing coating onto the surface of the intermediate functional layer, the coating thickness is 0.1 mm, cure under 365 nm ultraviolet light at an irradiation intensity of 1000 mV / cm 2 for 3 min to obtain an intermediate material layer with a UV cured coating; hot press the intermediate material layer with the UV cured coating away from the UV cured coating onto the transparent substrate layer, press at 80°C under a pressure of 0.5 MPa for 2-3 minutes, uniformly coat 0.05 mm thick pressure-sensitive adhesive on the other surface of the well-bonded transparent substrate layer by gravure coating, obtain an adhesive layer, cover a release film on the adhesive layer and roll, cover a protective film on the UV cured coating to obtain a solvent-resistant and scratch-resistant stealth car paint.

[0080] Example 4

[0081] Example 4 is based on Example 3, and the difference between Example 4 and Example 3 is only that naphthalene diisocyanate is replaced by toluene diisocyanate in Example 4.

[0082] Example 5

[0083] Example 5 is based on Example 3, and the difference between Example 5 and Example 3 is only that bisphenol S is replaced by bisphenol A in Example 5.

[0084] Example 6

[0085] Example 6 is based on Example 3, and the difference between Example 6 and Example 3 is only that the amount of epoxy acrylate is 47.62 kg and the amount of dodecafluoroheptyl propyl trimethoxysilane is 2.38 kg in Example 6.

[0086] Example 7

[0087] Example 7 is based on Example 3, and the difference between Example 7 and Example 3 is only that the amount of epoxy acrylate is 35.71 kg and the amount of dodecafluoroheptyl propyl trimethoxysilane is 14.29 kg in Example 7.

[0088] Example 8

[0089] Example 8 is based on Example 3, the difference between Example 8 and Example 3 is only that the modified zirconium phosphate nanosheet chain extender step in Example 8 does not modify the zirconium phosphate nanosheet, the hydroxylated zirconium phosphate nanosheet is replaced by zirconium phosphate nanosheet.

[0090] Example 9

[0091] Example 9 is based on Example 3, the difference between Example 9 and Example 3 is only that the N-(β-aminoethyl)-γ-aminopropyl trimethoxysilane is replaced by methyl trimethoxysilane in Example 9.

[0092] Example 10

[0093] Example 10 is based on Example 3, the difference between Example 10 and Example 3 is only that the photoinitiator does not add 1-hydroxycyclohexyl phenyl ketone in Example 10.

[0094] Example 11

[0095] Example 11 is based on Example 3, the difference between Example 11 and Example 3 is only that the photoinitiator does not add bis(4-tert-butylphenyl) iodonium tetraphenylborate in Example 11.

[0096] Example 12

[0097] Example 12 is based on Example 3, the difference between Example 12 and Example 3 is only that the amount of polyurethane elastomer is 68.97 kg, the amount of ethylene-vinyl acetate copolymer is 27.59 kg, and the amount of nanoclay is 3.44 kg in Example 12.

[0098] Example 13

[0099] Example 13 is based on Example 3, the difference between Example 13 and Example 3 is only that the amount of polyurethane elastomer is 60.61 kg, the amount of ethylene-vinyl acetate copolymer is 24.24 kg, and the amount of nanoclay is 15.15 kg in Example 13.

[0100] Comparative Example 1

[0101] Comparative Example 1 is based on Example 3, the difference between Comparative Example 1 and Example 3 is only that the silicone-modified epoxy acrylate is replaced by epoxy acrylate in Comparative Example 1.

[0102] Comparative Example 2

[0103] Comparative Example 2 is based on Example 3, the difference between Comparative Example 2 and Example 3 is only that the modified zirconium phosphate nanosheet chain extender is replaced by zirconium phosphate nanosheet in Comparative Example 2.

[0104] Performance test

[0105] (1) Scratch resistance test: ASTM D3363 was selected as the standard, and the surface of the sample was scratched with a pencil of known hardness at an angle of 45° to determine the highest pencil hardness without leaving scratches. The results are recorded in Table 1.

[0106] (2) Solvent resistance test: ASTM D5894 was selected as the standard, and cotton was dipped in methyl ethyl ketone and wiped back and forth on the surface of the car paint at a speed of 60 times / min. The highest wiping number without sample shedding or discoloration was recorded, and each sample was tested three times. The average value was measured after measurement, and the results are recorded in Table 1.

[0107] (3) Puncture resistance test: QC / T1171-2022 Automotive Paint Film was selected as the standard to test the puncture resistance of the sample. Each sample was tested three times, and the average value was measured after measurement. The results are recorded in Table 1.

[0108] Table 1 Detection results of scratch resistance, solvent resistance and puncture resistance of invisible car paint

[0109] Detection result Hardness Maximum wiping number (times) Puncture resistance (N) Example 1 2H 687 218 Example 2 3H 724 225 Example 3 3H 721 224 Example 4 2H 625 212 Example 5 2H 608 207 Example 6 2H 646 214 Example 7 2H 614 207 Example 8 2H 637 212 Example 9 2H 593 195 Example 10 2H 638 215 Example 11 2H 625 211 Example 12 2H 628 213 Example 13 2H 633 210 Comparative Example 1 H 547 162 Comparative Example 2 H 532 148

[0110] As can be seen from Table 1, the hardness of Examples 1-3 is greater than 2H, the highest wiping number is greater than 687 times, and the puncture resistance is greater than 221N, so it can be seen that the invisible car paint prepared in the present application has good solvent resistance, scratch resistance and puncture resistance.

[0111] As can be seen from Table 1, the difference between Examples 4, 5 and Example 3 is that in Example 4, naphthalene diisocyanate is replaced by toluene diisocyanate, and in Example 5, bisphenol S is replaced by bisphenol A. Compared with Examples 4, 5 and Example 3, the performance decreases; this is because the synthesis components of the polyurethane prepolymer are replaced, lacking rigid and high conjugated structure, the density of the molecular crosslinking network decreases, the stability decreases, and thus the performance of the car paint decreases.

[0112] As can be seen from Table 1, the difference between Examples 6, 7 and Example 3 is that in Example 6, the mass ratio of epoxy acrylate and dodecafluoroheptyl propyl trimethoxysilane is 1:0.05, and in Example 7, the mass ratio of epoxy acrylate and dodecafluoroheptyl propyl trimethoxysilane is 1:0.4. Compared with Examples 6, 7 and Example 3, the performance decreases; this is because the optimal ratio of silicone-modified epoxy acrylate is destroyed, too little dodecafluoroheptyl propyl trimethoxysilane will affect the modification effect, leading to the increase of the surface energy of the coating and the decrease of the crosslinking density; too much dodecafluoroheptyl propyl trimethoxysilane will lead to excessive crosslinking, causing local stress concentration and weakening the performance of the car paint.

[0113] From Table 1, it can be seen that the difference between Example 8, 9 and Example 3 is only that the hydroxylated zirconium phosphate nanosheet is replaced by zirconium phosphate nanosheet in Example 8, and N-(β-aminoethyl)-γ-aminopropyl trimethoxysilane is replaced by methyl trimethoxysilane in Example 9, and the performance of Example 8, 9 and Example 3 is decreased; this is because the components of the modified zirconium phosphate nanosheet chain extender are replaced, if the hydroxyl modification treatment is not performed, the active sites on the surface of the nanosheet are reduced, and the modification effect of the amino silane coupling agent is decreased; if the amino silane coupling agent is replaced by methyl trimethoxysilane, the introduction of amino is lacking, it is difficult to introduce into the molecular chain as a chain extender, the compatibility is decreased, and the reinforcing effect is weakened, so the performance is decreased.

[0114] From Table 1, it can be seen that the difference between Example 10, 11 and Example 3 is only that 1-hydroxycyclohexyl phenyl ketone is not added in the photoinitiator in Example 10, and bis(4-tert-butylphenyl) iodonium tetraphenylborate is not added in the photoinitiator in Example 11, and the performance of Example 10, 11 and Example 3 is decreased; this is because reducing the components of the photoinitiator will affect the synergistic effect of the two photoinitiators, and the photoinitiation efficiency is decreased, so the reaction is affected, the stability of the molecular chain structure is decreased, and the performance is decreased.

[0115] From Table 1, it can be seen that the difference between Example 12, 13 and Example 3 is only that the mass ratio of the polyurethane elastomer, ethylene-vinyl acetate copolymer and nanoclay is 1:0.4:0.05 in Example 12, and the mass ratio of the polyurethane elastomer, ethylene-vinyl acetate copolymer and nanoclay is 1:0.4:0.25 in Example 13, and the performance of Example 12, 13 and Example 3 is decreased; this is because the optimal ratio of the components in the intermediate functional layer is destroyed, which will affect the synergistic effect between the components, and then affect the performance of the intermediate functional layer and the lamination effect with other layers, and the performance of the car skin is decreased.

[0116] From Table 1, it can be seen that the difference between Comparative Example 1 and Example 3 is only that the silicone-modified epoxy acrylate is replaced by epoxy acrylate in Comparative Example 1, and the performance of Comparative Example 1 and Example 3 is obviously decreased; this is because no modification treatment is performed with fluorosilane, the crosslinking structure is poor, the surface energy is increased, and the performance is obviously decreased.

[0117] From Table 1, it can be seen that the difference between Comparative Example 2 and Example 3 is only that the modified zirconium phosphate nanosheet chain extender is replaced by zirconium phosphate nanosheet in Comparative Example 2, and the performance of Comparative Example 2 and Example 3 is obviously decreased; this is because of the lack of modification treatment, the dispersibility and reactivity of the zirconium phosphate nanosheet are decreased, the reinforcing effect is weakened, the improvement of the system is reduced, and the performance is obviously decreased.

[0118] The specific embodiments are only an explanation of the present application, and are not a limitation of the present application, through the above description, relevant staff can make various changes and modifications without deviating from the technical idea of the present application. The technical scope of the present application is not limited to the content of the specification, and the technical scope must be determined according to the scope of claims.

Claims

1. A solvent-resistant and scratch-resistant paint protection film, characterized in that: The coating comprises a protective film, a UV-curable coating, an intermediate functional layer, a transparent substrate layer, an adhesive layer, and a release film. The UV-curable coating is obtained by applying a UV-curable paint, and the raw materials for preparing the UV-curable paint include the following components in parts by weight: 50-70 parts of polyurethane prepolymer 20-30 parts of silicone-modified epoxy acrylate 5-15 parts of modified zirconium phosphate nanosheet chain extender 1-3 parts of composite photoinitiator 1-3 parts light stabilizer Antioxidant 0.5-1 part Solvent 20-30 parts; The raw materials for preparing the polyurethane prepolymer include naphthalene diisocyanate and bisphenol S; The raw materials for preparing the organosilicon-modified epoxy acrylate include epoxy acrylate and dodecafluoroheptylpropyltrimethoxysilane. The mass ratio of the epoxy acrylate to dodecafluoroheptylpropyltrimethoxysilane is 1:(0.1-0.3). The raw materials for preparing the modified zirconium phosphate nanosheet chain extender include hydroxylated zirconium phosphate nanosheets and an aminosilane coupling agent. The composite photoinitiator includes 1-hydroxycyclohexylphenyl ketone and bis(4-tert-butylphenyl)iodonium tetraphenylborate; The raw materials for preparing the intermediate functional layer include polyurethane elastomer, ethylene-vinyl acetate copolymer and nano clay. The mass ratio of the polyurethane elastomer, ethylene-vinyl acetate copolymer and nano-clay is 1:0.4:(0.1-0.2).

2. The solvent-resistant and scratch-resistant paint protection film according to claim 1, characterized in that: The modified zirconium phosphate nanosheet chain extender was prepared using the following steps: Zirconium phosphate nanosheets were dispersed in dilute hydrochloric acid solution to obtain a nanosheet dispersion. The nanosheet dispersion was stirred in a water bath and reacted. After the reaction was completed, the mixture was cooled, centrifuged to discard the supernatant, and the precipitate was washed and dried to obtain hydroxylated zirconium phosphate nanosheets. Hydroxylated zirconium phosphate nanosheets were dispersed in toluene and sonicated to obtain a dispersion. An aminosilane coupling agent was added to the nanosheet dispersion, and the mixture was heated, stirred, and refluxed. After the reaction was completed, the mixture was cooled, washed, and dried to obtain a modified zirconium phosphate nanosheet chain extender.

3. A method for preparing a solvent-resistant and scratch-resistant paint protection film as described in any one of claims 1-2, characterized in that: Includes the following steps: Polyurethane prepolymer, silicone-modified epoxy acrylate, and modified zirconium phosphate nanosheet chain extender are dispersed in a solvent, stirred and mixed, and then a composite photoinitiator, light stabilizer, and antioxidant are added and stirred and mixed to obtain a UV-curable coating. A UV-curable coating is applied to the surface of the intermediate functional layer, and after UV curing, an intermediate material layer with a UV-curable coating is obtained. The intermediate material layer with UV-curable coating is hot-pressed onto the transparent substrate layer on the side away from the UV-curable coating. Pressure-sensitive adhesive is then evenly coated onto the other surface of the bonded transparent substrate layer to obtain an adhesive layer. A release film is then covered onto the adhesive layer and rolled. Finally, a protective film is applied to the surface of the UV-curable coating to obtain a solvent-resistant and scratch-resistant paint protection film.