Preparation method of triple-curing self-repairing coating liquid and paint surface protective film

Abstract

The invention discloses a preparation method of a triple-curing self-repairing coating liquid, which comprises the following steps: 1) adding 75-300 parts by weight of hydroxyl-terminated polybutadiene, 25-134 parts by weight of methyldiethoxysilane and 0.1-0.43 part by weight of a platinum catalyst into 150-650 parts by weight of an organic solvent, reacting for 30 minutes under the protection of nitrogen at the reaction temperature of 70 DEG C, and then cooling to room temperature; and 2) adding 400-1850 parts by weight of modified polyol resin, 10-21 parts by weight of a metal catalyst, 15-32 parts by weight of an ultraviolet absorbent, 2-4 parts by weight of a leveling agent, 2-4 parts by weight of a defoaming agent, 0.13-0.5 part by weight of a main drier and 0.27-1.0 part by weight of an auxiliary drier into 1000-3000 parts by weight of an organic solvent, uniformly stirring, adding the mixture into the solvent system in the step 1), finally adding 168-250 parts by weight of an isocyanate curing agent, and stirring for 2 hours to obtain the triple-curing self-repairing coating liquid. The technical problem that the paint surface protective film has installation performance and stain resistance and also keeps self-repairing performance is solved, and the stain resistance of the surface of the paint surface protective film is obviously improved.

Description

Technical Field

[0001] The present invention relates to a method for preparing a self-repairing coating liquid, in particular a method for preparing a triple-curing self-repairing coating liquid. The present invention also relates to a paint surface protective film. Background Art

[0002] Paint Protection Film (PPF), also known as "invisible car wrap," is a transparent protective film applied to the surface of a car's body. It effectively protects against scratches and sand, isolates the paint from air, and prevents corrosion from acid rain, insects, bird droppings, and other factors. Its primary purpose is to preserve the original paint's shine after removal.

[0003] Existing paint protection films generally consist of three layers: a self-healing coating, a TPU base layer, and a pressure-sensitive adhesive layer, from top to bottom. The TPU base layer primarily serves as a support layer, its inherent toughness providing a buffer against external impacts. The self-healing coating, the outermost layer of the film, provides scratch repair, dirt isolation, and UV protection. The pressure-sensitive adhesive layer secures the film to the paint surface, preventing yellowing and debonding.

[0004] Current self-healing coatings are mostly made of polyurethane. The hardness of the coating directly affects the installation and stain resistance of the PPF. A coating that is too hard makes the PPF difficult to stretch and install, but offers excellent stain resistance. A coating that is too soft stretches and simplifies installation, but offers poor stain resistance and is prone to rain stains. Therefore, installation and stain resistance are conflicting properties, making achieving both installation and stain resistance in paint protection films a pressing technical challenge.

[0005] Therefore, the present invention is proposed. Summary of the Invention

[0006] One of the inventive objectives of the present invention is to provide a method for preparing a triple-curing self-repairing coating liquid. The triple-curing self-repairing coating liquid prepared by this preparation method is applied to a paint protection film. The triple-curing self-repairing coating liquid forms a triple-curing self-repairing coating on the surface of the TPU substrate layer of the paint protection film through three reaction processes: heat curing, moisture curing, and oxygen curing. This does not affect the installability of the paint protection film because the hardness of the polyurethane coating generated by the triple-curing self-repairing coating after the first heat curing reaction during installation is relatively low, making it easy to attach the paint protection film to the car body. After installation, the polyurethane coating undergoes a second moisture curing and a third oxygen curing reaction, resulting in a further increase in hardness, thereby enhancing the stain resistance of the paint protection film.

[0007] Another object of the present invention is to provide a paint protection film that has both installation properties and stain resistance.

[0008] In order to achieve the above object, the present invention provides a method for preparing a triple-curing self-repairing coating liquid, which comprises the following steps: 1) adding 75-300 parts by weight of hydroxy-terminated polybutadiene, 25-134 parts of methyldiethoxysilane, and 0.1-0.43 parts of platinum catalyst to 150-650 parts of organic solvent, reacting for 30 minutes at 70° C. under nitrogen protection, and then cooling to room temperature; 2) By weight, 400-1850 parts of a modified polyol resin, 10-21 parts of a metal catalyst, 15-32 parts of a UV absorber, 2-4 parts of a leveling agent, 2-4 parts of a defoaming agent, 0.13-0.5 parts of a primary drier, and 0.27-1.0 parts of an auxiliary drier are added to 1000-3000 parts of an organic solvent and stirred uniformly. The mixture is then added to the solvent system described in 1) above, and finally 168-250 parts of an isocyanate curing agent is added, and the mixture is stirred for 2 hours to obtain a triple-curing self-healing coating liquid.

[0009] The number average molecular weight of the hydroxyl-terminated polybutadiene is preferably between 2000 and 4500, and the hydroxyl value thereof is preferably between 0.5 and 1.4 mmol / g.

[0010] The modified polyol resin is preferably selected from polyester polyol resin, polycarbonate polyol resin or polycaprolactone polyol resin, or a combination of at least two thereof.

[0011] The selected isocyanate curing agent is preferably selected from toluene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), TDI trimer, HDI trimer and IPDI trimer, or a combination of at least two thereof.

[0012] The platinum catalyst is preferably selected from one of H2PtCl6·6H2O, Pt(dvs), Pt(dcp), PdCl2, Pd(Ph3P)4, RhCl(Ph3P)3, Co2(CO)8, Ni(CO)4, and Cr(CO)6; The metal catalyst is preferably selected from one of dibutyltin dilaurate, stannous isooctanoate, zinc isooctanoate, and bismuth isooctanoate; The ultraviolet absorber is preferably selected from one of TINUVIN 99-2, TINUVIN 384-2, TINUVIN 400, TINUVIN477, TINUVIN 900, TINUVIN1130, or a combination of at least two thereof; The leveling agent is preferably a modified organic siloxane; further preferably one of DC 29, DC 51, Tego450, Tego 410, Tego 432, Tego B1484, Tego G100, Tego G496, BYK 307, BYK 320, BYK 332, or a combination of at least two thereof.

[0013] The defoaming agent is preferably selected from one of BYK 1790, BYK 1791, BYK 1794, and BYK A535, or a combination of at least two thereof; The primary drier is preferably selected from cerium naphthenate, cerium octoate, or one of the Borchi® OXY-Coat series; The auxiliary drying agent is preferably selected from one of zinc naphthenate, zinc octoate, zinc neodecanoate, calcium naphthenate, calcium octoate, zirconium naphthenate, and zirconium octoate.

[0014] The organic solvent is preferably selected from one of butanone, methyl isobutyl ketone, toluene, xylene, ethyl acetate, butyl acetate, propylene glycol methyl ether acetate, and dimethylacetamide, or a combination of at least two thereof.

[0015] The triple-curing self-repairing coating liquid prepared by the above preparation method is applied to the paint protection film, which can form a triple-curing self-repairing coating on the surface of the TPU substrate layer of the paint protection film through heat curing-moisture curing-oxygen curing reaction, and the first heat curing reaction process will occur in the preparation process of the paint protection film. After coating on the surface of the TPU substrate, it will undergo the first heat curing reaction, so that the triple-curing self-repairing coating has a certain hardness, but the hardness is relatively low at this time, so it is easy to install. The second moisture curing reaction and the third oxygen curing reaction will occur in the installation process of the paint protection film. After the paint protection film is installed on the car body, the coating hardness will be further improved, and then the stain resistance of the paint protection film will be further improved, achieving excellent stain resistance. The specific reaction mechanism is as follows: In the preparation process of the triple-curing self-healing coating liquid: a segment with both moisture-curing and oxidation-curing groups is synthesized. The specific chemical reaction process is shown in the following formula (1): (1) In the formula, methyldiethoxysilane first reacts with double bonds in the main chain or side chains of the hydroxy-terminated polybutadiene through a hydrosilylation reaction, attaching hydrolyzable, cross-linkable ethoxy groups to the hydroxy-terminated polybutadiene. A portion of double bonds remain in the main chain of the hydroxy-terminated polybutadiene, which can undergo oxidative curing. The coating is then mixed evenly with a modified polyol resin, an isocyanate curing agent, and other functional additives to produce a triple-cured self-healing coating solution.

[0017] During the preparation process of the paint protection film: the triple-curing self-repairing coating liquid is applied to the surface of the TPU substrate, and after heating, the first thermal curing reaction occurs to form a polyurethane coating (i.e., the triple-curing self-repairing coating).

[0018] During the paint protection film application process, the paint protection film undergoes a second moisture curing reaction. This is because wet application requires the use of a mounting solution made from shower gel and water. The acidic pH of the mounting solution and the metal catalyst remaining in the polyurethane coating promote the hydrolysis and cross-linking of the siloxy groups. Then, the oxygen in the air and the drying agent in the coating promote cross-linking of the double bonds in the chain segments, which is the third oxygen curing reaction. The specific chemical reaction process is shown in Equation (2).

[0019]

[0020]

[0021]

[0022] In addition, the ethoxy groups in the polyurethane coating chain segments can not only cross-link themselves into a network structure, but also react with the hydroxyl groups in the TPU substrate to enhance the interaction between the coating and the TPU substrate layer, thereby increasing the service life of the paint protection film product.

[0023] The paint protection film designed by the present invention includes a triple-cured self-repairing coating obtained by curing the triple-cured self-repairing coating liquid described above, a TPU substrate layer, a pressure-sensitive adhesive layer and a release film layer; wherein the triple-cured self-repairing coating, the TPU substrate layer, the pressure-sensitive adhesive layer and the release film layer are laminated in sequence.

[0024] Wherein, the thickness of the triple-cured self-repairing coating is preferably selected to be 6 to 12 μm.

[0025] The TPU substrate layer preferably adopts an aliphatic TPU substrate, whose surface hardness is preferably selected to be 80A~93A, the visible light transmittance is preferably selected to be more than 90%, the elongation at break is preferably selected to be more than 300%, the haze is preferably selected to be less than 2%, and the thickness is preferably selected to be 100~300μm.

[0026] The installation adhesive layer is preferably made of transparent acrylic pressure-sensitive adhesive or polyurethane pressure-sensitive adhesive, the visible light transmittance of which is preferably above 90%, and the thickness is preferably 20 to 50 μm.

[0027] The release film layer is preferably made of a white PET release film, the haze of which is preferably above 70%, the release force is preferably within 20 g / inch, and the thickness is preferably 50 to 100 μm.

[0028] Furthermore, the above-mentioned paint protection film preferably includes a transparent PET protective film layer with a thickness of 23 to 75 μm in its layered structure, which is laminated onto the surface of the triple-cured self-repairing coating. It can not only protect the surface of the triple-cured self-repairing coating, but also prevent water vapor from penetrating into the triple-cured self-repairing coating.

[0029] The above-mentioned paint protection film is preferably prepared by first coating a pressure-sensitive adhesive layer and then coating a triple-curing self-repairing coating, and the coating method is preferably roller coating, slit coating or comma blade coating. The specific preparation steps are as follows: Step 1: Pre-prepare a triple-curing self-repairing coating liquid as described above; Step 2: Apply the pressure-sensitive adhesive liquid on the release film layer and dry it at 80-120°C for 2-3 minutes to form a pressure-sensitive adhesive layer, which is then laminated with the TPU substrate layer. Step 3: Apply a triple-curing self-repairing coating liquid on the reverse side of the TPU substrate layer in step 2 above, curing under the conditions of 80-150°C for 2-4 minutes to form a triple-curing self-repairing coating, and then coat the surface with a protective film layer; Compared with the prior art, the preparation method of a triple-curing self-repairing coating liquid and a paint protection film obtained in the present invention have the following technical effects: A triple-curing self-repairing coating liquid prepared by the method of the present invention is applied to a paint protective film, and undergoes heat curing before installation of the paint protective film, moisture curing during installation, and oxidation curing after installation. Heat curing before installation makes the coating have a certain hardness, but the hardness is relatively low, so the paint protective film has good installability; after installation, after two additional curings (moisture curing and oxidation curing), the hardness of the coating is further improved, so that the stain resistance of the paint protective film is greatly improved.

[0030] The two curing steps, during and after installation, require no additional steps, perfectly matching the paint protection film's operating environment. The film requires a wet application with a water spray, and the acidic installation fluid is ideal for moisture curing. Oxygen in the air also promotes further oxidative curing of the film. These two curing processes can also complement each other; even if one cures incompletely, the other can still cure, ensuring the film's improved stain resistance.

[0031] The paint protection film of the present invention has both installation properties and stain resistance and also maintains the self-repairing performance of the paint protection film. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the layered structure of a paint protection film.

[0033] In the figure: transparent PET protective film layer 1, triple-cured self-repairing coating 2, TPU substrate layer 3, pressure-sensitive adhesive layer 4, white PET release film layer 5. DETAILED DESCRIPTION

[0034] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention are within the scope of protection of the present invention. Example 1:

[0035] The method for preparing a triple-curing self-repairing coating liquid provided in this embodiment includes the following steps: 1) By weight, 75 parts of hydroxy-terminated polybutadiene (Qilong Chemical Co., Ltd., Mn=2000), 25 parts of methyldiethoxysilane (Aladdin Chemical Reagent Network), and 0.1 parts of Pt(dvs) catalyst (Aladdin Chemical Reagent Network) were added to 150 parts of ethyl acetate and reacted under nitrogen at 70°C for 30 minutes, followed by cooling to room temperature. 2) By weight, 1850 parts of polycaprolactone polyol resin (Daicel ChemTech, PLACCEL 220CPT), 21 parts of stannous isooctanoate (Aladdin Chemical Reagent Network), 32 parts of TINUVIN 400 UV absorber (BASF), 4 parts of Tego 450 leveling agent (Evonik), 4 parts of BYK 1790 defoamer (BYK Chemical), 0.13 parts of cerium naphthenate primary drier (Wuhan Kamik), and 0.27 parts of zinc naphthenate auxiliary drier (Aladdin Chemical Reagent Network) were added to 3000 parts of ethyl acetate and stirred evenly. The mixture was then added to the solvent system in the previous section. Finally, 168 parts of HDI isocyanate curing agent (Wanhua Chemical) was added and stirred for 2 hours to obtain a triple-cured self-healing coating solution.

[0036] like Figure 1 As shown, a paint protection film provided in this embodiment includes a 23 μm thick transparent PET protective film layer (Yihua Toray, G01), a 6 μm thick triple-cured self-repairing coating, a 100 μm thick TPU substrate layer (Argotec 49510), a 20 μm thick pressure-sensitive adhesive layer (Henkel, Loctite 8087), and a 50 μm thick white PET release film layer (Toray, XZ31SR); The triple-cured self-repairing coating is obtained by curing the triple-cured self-repairing coating liquid prepared in this embodiment; Among them, the triple-cured self-repairing coating, TPU substrate layer, pressure-sensitive adhesive layer and release film layer are laminated in sequence.

[0037] The method for preparing a paint protection film provided in this embodiment includes the following steps: In step 1, a pressure-sensitive adhesive liquid (Henkel, Loctite 8087) was coated on one side of a 50 μm thick white PET release film (Toray, XZ31SR) and dried at 110°C for 2 minutes to form a pressure-sensitive adhesive layer with a dry adhesive thickness of 20 μm. This pressure-sensitive adhesive layer was then covered on one side of a 100 μm thick TPU substrate (Argotec 49510).

[0038] Step 2: The triple-curing self-repairing coating liquid is applied to the other surface of the TPU substrate in step 1. The curing condition is 120°C for 3 minutes. After drying, the thickness of the triple-curing self-repairing coating is 6 μm. Finally, a 23 μm transparent PET protective film (Yihua Toray, G01) is covered on the surface of the triple-curing self-repairing coating. Step three: Place the semi-finished product in the second step into a 50°C vacuum oven for 72 hours to obtain a super-fouling-resistant paint protection film. Example 2:

[0039] The method for preparing a triple-curing self-repairing coating liquid provided in this embodiment includes the following steps: 1) By weight, 100 parts of hydroxy-terminated polybutadiene (Qilong Chemical Co., Ltd., Mn=2000), 40 parts of methyldiethoxysilane (Aladdin Chemical Reagent Network), and 0.14 parts of Pt(dvs) catalyst (Aladdin Chemical Reagent Network) were added to 210 parts of ethyl acetate and reacted under nitrogen at 70°C for 30 minutes, followed by cooling to room temperature. 2) By weight, 1800 parts of polycaprolactone polyol resin (Daicel ChemTech, PLACCEL 220CPT), 21 parts of stannous isooctanoate (Aladdin Chemical Reagent Network), 32 parts of TINUVIN 400 UV absorber (BASF), 4 parts of Tego 450 leveling agent (Evonik), 4 parts of BYK 1790 defoamer (BYK Chemical), 0.17 parts of cerium naphthenate primary drier (Wuhan Kamik), and 0.33 parts of zinc naphthenate auxiliary drier (Aladdin Chemical Reagent Network) were added to 2900 parts of ethyl acetate and stirred evenly. The mixture was then added to the solvent system in the previous section. Finally, 168 parts of HDI isocyanate curing agent (Wanhua Chemical) was added and stirred for 2 hours to obtain a triple-cured self-healing coating solution.

[0040] The layered structure and preparation method of the paint protection film provided in this embodiment are generally consistent with those of the aforementioned Example 1, but the thickness of the pressure-sensitive adhesive layer (Henkel, Loctite 8087) of the paint protection film in this embodiment is 30 μm. In addition, the triple-cured self-repairing coating of the paint protection film is obtained by curing the triple-cured self-repairing coating liquid prepared in this embodiment. Example 3:

[0041] The method for preparing a triple-curing self-repairing coating liquid provided in this embodiment includes the following steps: 1) By weight, 155 parts of hydroxyl-terminated polybutadiene (Qilong Chemical Co., Ltd., M n =2500), 60 parts of methyldiethoxysilane (Aladdin Chemical Reagent Network) and 0.22 parts of Pt(dvs) catalyst (Aladdin Chemical Reagent Network) were added to 330 parts of ethyl acetate, reacted under nitrogen protection at a reaction temperature of 70°C for 30 minutes, and then cooled to room temperature; 2) By weight, 875 parts of polycarbonate polyol resin (Daicel ChemTech, PLACCEL CD210), 13 parts of stannous isooctanoate (Aladdin Chemical Reagent Network), 20 parts of TINUVIN 99-2 UV absorber (BASF), 3 parts of Tego 410 leveling agent (Evonik), 3 parts of BYK 1791 defoamer (BYK Chemical), 0.27 parts of cerium naphthenate primary drier (Wuhan Kamik), and 0.53 parts of zinc naphthenate auxiliary drier (Aladdin Chemical Reagent Network) were added to 1600 parts of ethyl acetate and stirred evenly. The mixture was then added to the solvent system in the previous section. Finally, 222 parts of IPDI isocyanate curing agent (Wanhua Chemical) was added and stirred for 2 hours to obtain a triple-cured self-healing coating solution.

[0042] Similarly, the layered structure and preparation method of the paint protection film provided in this embodiment are generally consistent with those of the aforementioned Example 1, but the thickness of the transparent PET protective film layer (Yihua Toray, G01) in this embodiment is 50 μm, the thickness of the triple-cured self-repairing coating is 9 μm, the thickness of the TPU substrate layer (Argotec 49510) is 150 μm, the thickness of the pressure-sensitive adhesive layer (Henkel, Loctite 8087) is 30 μm, and the thickness of the white PET release film layer (Toray, XZ31SR) is 75 μm. In addition, the triple-cured self-repairing coating of the paint protection film is obtained by curing the triple-cured self-repairing coating liquid prepared in this embodiment. Example 4:

[0043] The method for preparing a triple-curing self-repairing coating liquid provided in this embodiment includes the following steps: 1) By weight, 190 parts of hydroxyl-terminated polybutadiene (Qilong Chemical Co., Ltd., M n =2500), 80 parts of methyldiethoxysilane (Aladdin Chemical Reagent Network) and 0.27 parts of PdCl2 catalyst (Aladdin Chemical Reagent Network) were added to 400 parts of ethyl acetate, reacted under nitrogen protection for 30 minutes at a reaction temperature of 70°C, and then cooled to room temperature; 2) By weight, 850 parts of polycarbonate polyol resin (Daicel ChemTech, PLACCEL D210), 13 parts of dibutyltin dilaurate (Aladdin Chemical Reagent Network), 20 parts of TINUVIN 99-2 UV absorber (BASF), 3 parts of Tego 410 leveling agent (Evonik), 3 parts of BYK 1791 defoamer (BYK Chemical), 0.32 parts of Borchi®OXY - Coat 1101 primary drier (Boshes), and 0.63 parts of zinc neodecanoate auxiliary drier (Aladdin Chemical Reagent Network) were added to 1600 parts of ethyl acetate and stirred evenly. The mixture was then added to the solvent system in the previous section. Finally, 222 parts of IPDI isocyanate curing agent (Wanhua Chemical) were added and stirred for 2 hours to obtain a triple-cured self-healing coating solution.

[0044] Similarly, the layered structure and preparation method of the paint protection film provided in this embodiment are generally consistent with those of the aforementioned Example 1, but the thickness of the transparent PET protective film layer (Yihua Toray, G01) in this embodiment is 50 μm, the thickness of the triple-cured self-repairing coating is 9 μm, the thickness of the TPU substrate layer (Argotec 49510) is 150 μm, the thickness of the pressure-sensitive adhesive layer (Henkel, Loctite 8087) is 40 μm, and the thickness of the white PET release film layer (Toray, XZ31SR) is 75 μm. In addition, the triple-cured self-repairing coating of the paint protection film is obtained by curing the triple-cured self-repairing coating liquid prepared in this embodiment. Example 5:

[0045] The method for preparing a triple-curing self-repairing coating liquid provided in this embodiment includes the following steps: 1) By weight, 260 parts of hydroxyl-terminated polybutadiene (Qilong Chemical Co., Ltd., M n =3000), 105 parts of methyldiethoxysilane (Aladdin Chemical Reagent Network) and 0.37 parts of PdCl2 catalyst (Aladdin Chemical Reagent Network) were added to 550 parts of ethyl acetate, reacted under nitrogen protection for 30 minutes at a reaction temperature of 70°C, and then cooled to room temperature; 2) By weight, 420 parts of polyester polyol resin (Kuraray, P-150), 10 parts of dibutyltin dilaurate (Aladdin Chemical Reagent Network), 15 parts of TINUVIN 1130 UV absorber (BASF), 2 parts of Tego 432 leveling agent (Evonik), 2 parts of BYK 1794 defoamer (BYK Chemical), 0.43 parts of Borchi® OXY-Coat1101 primary drier (Boshes), and 0.87 parts of zinc neodecanoate auxiliary drier (Aladdin Chemical Reagent Network) were added to 1000 parts of ethyl acetate and stirred evenly. The mixture was then added to the solvent system described in the previous section. Finally, 250 parts of MDI isocyanate curing agent (Wanhua Chemical) was added and stirred for 2 hours to obtain a triple-cured self-healing coating solution.

[0046] Similarly, the layered structure and preparation method of the paint protection film provided in this embodiment are generally consistent with those in the aforementioned Example 1, but the thickness of the transparent PET protective film layer (Yihua Toray, G01) in this embodiment is 75 μm, the thickness of the triple-cured self-repairing coating is 12 μm, the thickness of the TPU substrate layer (Argotec 49510) is 200 μm, the thickness of the pressure-sensitive adhesive layer (Henkel, Loctite 8087) is 40 μm, and the thickness of the white PET release film layer (Toray, XZ31SR) is 100 μm. In addition, the triple-cured self-repairing coating of the paint protection film is obtained by curing the triple-cured self-repairing coating liquid prepared in this embodiment. Example 6:

[0047] The method for preparing a triple-curing self-repairing coating liquid provided in this embodiment includes the following steps: 1) By weight, 300 parts of hydroxyl-terminated polybutadiene (Qilong Chemical Co., Ltd., M n =3000), 134 parts of methyldiethoxysilane (Aladdin Chemical Reagent Network) and 0.43 parts of PdCl2 catalyst (Aladdin Chemical Reagent Network) were added to 650 parts of ethyl acetate, reacted under nitrogen protection for 30 minutes at a reaction temperature of 70°C, and then cooled to room temperature; 2) By weight, 400 parts of polyester polyol resin (Kuraray, P-150), 10 parts of dibutyltin dilaurate (Aladdin Chemical Reagent Network), 15 parts of TINUVIN 1130 UV absorber (BASF), 2 parts of Tego 432 leveling agent (Evonik), 2 parts of BYK 1794 defoamer (BYK Chemical), 0.5 parts of Borchi® OXY-Coat1101 primary drier (Boshes), and 1.0 part of zinc neodecanoate auxiliary drier (Aladdin Chemical Reagent Network) were added to 1000 parts of ethyl acetate and stirred evenly. The mixture was then added to the solvent system described in the previous section. Finally, 250 parts of MDI isocyanate curing agent (Wanhua Chemical) were added and stirred for 2 hours to obtain a triple-cured self-healing coating solution.

[0048] Similarly, the layered structure and preparation method of the paint protection film provided in this embodiment are generally consistent with those in the aforementioned Example 1, but the thickness of the transparent PET protective film layer (Yihua Toray, G01) in this embodiment is 75 μm, the thickness of the triple-cured self-repairing coating is 12 μm, the thickness of the TPU substrate layer (Argotec 49510) is 300 μm, the thickness of the pressure-sensitive adhesive layer (Henkel, Loctite 8087) is 50 μm, and the thickness of the white PET release film layer (Toray, XZ31SR) is 100 μm. In addition, the triple-cured self-repairing coating of the paint protection film is obtained by curing the triple-cured self-repairing coating liquid prepared in this embodiment.

[0049] Comparative Example 1: A conventional method for preparing a paint protection film comprises the following steps: (1) Preparation of self-repairing coating liquid Self-healing coating liquid: 860 parts of polycaprolactone polyol resin (Daicel ChemTech, PLACCEL220CPT), 20 parts of stannous isooctanoate (Aladdin Chemical Reagent Network), 15 parts of UV absorber TINUVIN 400 (BASF), 10 parts of Tego 450 leveling agent (Evonik), and 10 parts of BYK 1790 defoamer (BYK Chemical) were added to 1000 parts of ethyl acetate in sequence. Finally, 150 parts of isocyanate curing agent toluene diisocyanate (Wanhua Chemical) was added and stirred for 30 minutes to mix thoroughly.

[0050] (2) Coating pressure-sensitive adhesive layer A pressure-sensitive adhesive liquid (Henkel, Loctite 8087) was coated on one side of a 50 μm thick white PET release film (Toray, XZ31SR) and dried at 110°C for 2 min to form a pressure-sensitive adhesive layer with a dry adhesive thickness of 20 μm. The pressure-sensitive adhesive layer was then covered on one side of a 100 μm thick TPU substrate (Argotec 49510).

[0051] (3) Applying self-repairing coating liquid In step (2), the other side of the TPU substrate was coated with the self-healing coating solution in step (1), and the curing conditions were 120 ° C for 2 min. After drying, a self-healing coating with a thickness of 6 μm was formed. Finally, a PET protective film with a thickness of 23 μm (Yihua Toray, G01) was covered on the surface.

[0052] (4) Late maturation The semi-finished product in step (3) is placed in a 50°C curing chamber for 72 hours to obtain a conventional paint protection film.

[0053] Comparative Example 2: Another conventional method for preparing a paint protection film comprises the following steps: (1) Preparation of self-repairing coating liquid Self-healing coating liquid: 1200 parts of polycarbonate polyol resin (Daicel ChemTech, PLACCEL D210), 26 parts of dibutyltin dilaurate (Aladdin Chemical Reagent Network), 20 parts of UV absorber TINUVIN 1130 (BASF), 13 parts of Tego 432 leveling agent (Evonik), and 13 parts of BYK 1794 defoamer (BYK Chemical) were added to 1200 parts of ethyl acetate in sequence. Finally, 100 parts of isocyanate curing agent hexamethylene diisocyanate (Wanhua Chemical) was added and stirred for 30 minutes to mix thoroughly.

[0054] (2) Coating pressure-sensitive adhesive layer A pressure-sensitive adhesive liquid (Henkel, Loctite 8087) was coated on one side of a 100 μm thick white PET release film (Toray, XZ31SR) and dried at 110°C for 2 min to form a pressure-sensitive adhesive layer with a dry adhesive thickness of 50 μm. The pressure-sensitive adhesive layer was then covered on one side of a 300 μm thick TPU substrate (Argotec 49510).

[0055] (3) Applying self-repairing coating liquid In step (2), the self-repairing coating solution in step (1) was applied to the other side of the TPU substrate, and the curing conditions were 120°C for 2 min. After drying, a repair coating with a thickness of 12 μm was formed. Finally, a PET protective film with a thickness of 75 μm (Yihua Toray, G01) was covered on the surface.

[0056] (4) Late maturation Place the semi-finished product in step (3) in a 50°C curing chamber for 72 hours to obtain another conventional paint protection film.

[0057] The following table shows the test data of the anti-fouling performance and self-repairing performance of the samples in Examples 1-6 and Comparative Examples 1 and 2.

[0058] Examples Stain resistance Self-repair performance Example 1 Level B qualified Example 2 Level A qualified Example 3 Level A qualified Example 4 Level A qualified Example 5 Level A qualified Example 6 Level A qualified Comparative Example 1 Level C qualified Comparative Example 2 Level C qualified From the above test data, it can be seen that the paint protection film combined with the triple-cured self-repairing coating of the present invention has better anti-fouling performance.

[0059] The test methods for each performance in the table are as follows: 1. Stain resistance test Select a paint protection film, remove the film and release film, and wet-apply the film to a white painted panel using a mounting solution mixed with shower gel and water. Leave the film at room temperature for 7 days. Apply a black Double-Eye marker evenly to the film. After leaving the film at room temperature for 2 hours, wipe the film clean with a clean cloth dipped in anhydrous alcohol. A grade of A indicates no residual marks, a grade of B indicates slight residual marks, and a grade of C indicates heavy residual marks.

[0060] 2. Self-repair performance test Select a piece of paint protection film, remove the protective film and release film, and wet-apply the film to a black painted panel using a combination of shower gel and water. Leave the film at room temperature for 7 days. Use a wire brush to vigorously scratch the surface, then place the film in a 70°C oven for 5 minutes. Observe to see if the scratches have fully healed. If so, the film is considered qualified.

[0061] The present invention is not limited to the above-mentioned optimal implementation mode. Anyone can derive other forms of products under the inspiration of the present invention. However, no matter what changes are made in the shape or structure, any technical solution that is the same or similar to that of the present application falls within the scope of protection of the present invention.

Claims

1. A method for preparing a triple-curing self-repairing coating liquid, characterized in that The steps include: 1) adding 75-300 parts by weight of hydroxy-terminated polybutadiene, 25-134 parts of methyldiethoxysilane, and 0.1-0.43 parts of platinum catalyst to 150-650 parts of organic solvent, reacting for 30 minutes at 70° C. under nitrogen protection, and then cooling to room temperature; 2) By weight, 400-1850 parts of a modified polyol resin, 10-21 parts of a metal catalyst, 15-32 parts of a UV absorber, 2-4 parts of a leveling agent, 2-4 parts of a defoaming agent, 0.13-0.5 parts of a primary drier, and 0.27-1.0 parts of an auxiliary drier are added to 1000-3000 parts of an organic solvent and stirred uniformly. The mixture is then added to the solvent system described in 1) above, and finally 168-250 parts of an isocyanate curing agent is added, and the mixture is stirred for 2 hours to obtain a triple-curing self-healing coating liquid.

2. The method for preparing a triple-curing self-repairing coating liquid according to claim 1, characterized in that: The number average molecular weight of the hydroxyl-terminated polybutadiene is between 2000 and 4500, and the hydroxyl value thereof is between 0.5 and 1.4 mmol / g.

3. The method for preparing a triple-curing self-repairing coating liquid according to claim 1, characterized in that: The modified polyol resin is one of polyester polyol resin, polycarbonate polyol resin or polycaprolactone polyol resin, or a combination of at least two of them.

4. The method for preparing a triple-curing self-repairing coating liquid according to claim 1, characterized in that: The selected isocyanate curing agent is one or a combination of at least two of toluene diisocyanate, diphenylmethane diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, TDI trimer, HDI trimer and IPDI trimer.

5. The method for preparing a triple-curing self-repairing coating liquid according to claim 1, characterized in that: The platinum catalyst is one of H2PtCl6·6H2O, Pt(dvs), Pt(dcp), PdCl2, Pd(Ph3P)4, RhCl(Ph3P)3, Co2(CO)8, Ni(CO)4, and Cr(CO)6; The metal catalyst is one of dibutyltin dilaurate, stannous isooctanoate, zinc isooctanoate, and bismuth isooctanoate; The ultraviolet absorber is one of TINUVIN 99-2, TINUVIN 384-2, TINUVIN 400, TINUVIN477, TINUVIN900, TINUVIN1130, or a combination of at least two thereof; The leveling agent is a modified organic siloxane; The defoamer is one of BYK 1790, BYK 1791, BYK 1794, BYK A535, or a combination of at least two thereof; The main drying agent is one of cerium naphthenate, cerium octoate, and Borchi® OXY-Coat series; The auxiliary drying agent is one of zinc naphthenate, zinc octoate, zinc neodecanoate, calcium naphthenate, calcium octoate, zirconium naphthenate, and zirconium octoate.

6. The method for preparing a triple-curing self-repairing coating liquid according to claim 5, characterized in that: The leveling agent is one of DC 29, DC 51, Tego 450, Tego 410, Tego 432, Tego B1484, Tego G100, Tego G496, BYK 307, BYK 320, BYK 332, or a combination of at least two thereof.

7. The method for preparing a triple-curing self-repairing coating liquid according to claim 1, characterized in that: The organic solvent is one of butanone, methyl isobutyl ketone, toluene, xylene, ethyl acetate, butyl acetate, propylene glycol methyl ether acetate, and dimethylacetamide, or a combination of at least two thereof.

8. A paint protection film comprising a TPU substrate layer, a pressure-sensitive adhesive layer and a release film layer, characterized in that It also includes a triple-cured self-repairing coating obtained by curing the triple-cured self-repairing coating liquid as described in any one of claims 1 to 7, and the triple-cured self-repairing coating, TPU substrate layer, pressure-sensitive adhesive layer and release film layer are laminated in sequence.

9. The paint protection film according to claim 8, characterized in that: The thickness of the triple-cured self-repairing coating is 6 to 12 μm; The TPU substrate layer is an aliphatic TPU substrate layer with a thickness of 100 to 300 μm; The mounting adhesive layer is a transparent acrylic pressure-sensitive adhesive layer or a polyurethane pressure-sensitive adhesive layer with a thickness of 20 to 50 μm; The release film layer is a white PET release film layer with a thickness of 50 to 100 μm.

10. A paint protection film according to claim 9, characterized in that The invention also includes a transparent PET protective film layer with a thickness of 23 to 75 μm, which is laminated on the surface of the triple-cured self-repairing coating.

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