Automobile paint surface protective film

Abstract

The utility model discloses an automobile protective film, in particular to an automobile paint surface protective film, which has a layered structure comprising a tetradecanoic acid modified SiO2 / hyperbranched PDMS (Polydimethylsiloxane) self-repairing coating, a TPU (Thermoplastic Polyurethane) base material layer, a pressure-sensitive adhesive layer and a release film layer which are compounded in sequence, wherein the tetradecanoic acid modified SiO2 / hyperbranched PDMS self-repairing coating is composed of a hyperbranched polysiloxane polymer coating and a tetradecanoic acid modified SiO2 deposition layer on the surface of the hyperbranched polysiloxane polymer coating. According to the utility model, the technical problem that the super-hydrophobic surface of the automobile paint protective film has a self-repairing function is solved. According to the super-hydrophobic surface with the self-repairing function, the contact angle of the super-hydrophobic coating is 152.61 degrees, the rolling angle of the super-hydrophobic coating is 1.9 degrees, the super-hydrophobic coating has excellent antifouling performance, scratches can be repaired through heat treatment for 2 hours at the temperature of 80 DEG C when the surface of the coating is damaged, and the super-hydrophobic coating has excellent self-repairing performance. In addition, the super-hydrophobic surface with the self-repairing function further has good weather resistance and mechanical stability.

Description

Technical Field

[0001] This utility model relates to an automotive protective film, and more particularly to an automotive paint protection film. Background Technology

[0002] Car paint protection film, also known as "invisible car wrap," is a transparent protective film applied to the surface of a car body. It effectively prevents scratches and impacts from sand particles, and also isolates the paint from contact with air, protecting it from corrosion by acid rain, insects, bird droppings, and other harmful substances. Its main purpose is to ensure that the car's original factory paint remains shiny and new after removal.

[0003] Currently, the selection of commercially available automotive paint protection films is relatively limited, meaning there isn't a wide variety of products. Existing automotive paint protection films generally have a three-layer structure: a repair coating, a TPU substrate layer, and a pressure-sensitive adhesive layer. The repair coating, made of polyurethane, is the outermost layer and serves to repair scratches and protect against dirt. However, the aforementioned repair coating has poor hydrophobic properties and lacks self-cleaning properties from rain. This allows dust and dirt (bird droppings, tree sap, etc.) to easily remain on the surface of the protective film for extended periods. With prolonged contact, these impurities can penetrate into the repair coating and TPU substrate layer, becoming impossible to remove later and ultimately affecting the lifespan of the protective film.

[0004] Zhu Hang, Liu Jing, and others proposed the preparation and superhydrophobic properties of a tetradecanoic acid-modified SiO2 / hyperbranched PDMS self-healing coating (Acta Materiae Compositae Sinica; Vol. 41, No. 1; January 2024). Their abstract clearly states that to improve the durability of the superhydrophobic coating, a bottom-up coating system of "substrate-viscous self-healing polymer-hydrophobic particles" was designed to prepare a superhydrophobic surface with self-healing function. Hyperbranched polysiloxane (HB-PDMS) with abundant hydrogen bonds was used as the viscous self-healing polymer, and tetradecanoic acid (MA) was used to hydrophobically modify nano-SiO2 to act as hydrophobic particles to construct a rough surface structure. The optimal SiO2 modification process was investigated: when the mass ratio of MA to SiO2 was 1:1 and the modification time was 3 h, the prepared superhydrophobic coating had a contact angle of 152.61° and a roll-off angle of 1.9°, exhibiting excellent antifouling properties. The coating can be repaired by simple heat treatment after being scratched by a blade, demonstrating excellent self-healing properties. In addition, after undergoing 5 tape peeling tests, a linear abrasion test with a wear length of 30 cm, a 50-minute ultrasonic oscillation test, 10 temperature difference cycles, and 24 hours of ultraviolet irradiation, the contact angle still remained above 150°, indicating that the coating has good weather resistance and mechanical stability.

[0005] Therefore, this utility model is proposed. Summary of the Invention

[0006] The purpose of this invention is to provide a superhydrophobic automotive paint protection film with self-healing function to overcome the shortcomings of the prior art.

[0007] To achieve the above objectives, the present invention provides an automotive paint protection film with a layered structure comprising: a tetradecanoic acid modified SiO2 / hyperbranched PDMS self-healing coating, a TPU substrate layer, a pressure-sensitive adhesive layer, and a release film layer, which are sequentially laminated; wherein the tetradecanoic acid modified SiO2 / hyperbranched PDMS self-healing coating is composed of a hyperbranched polysiloxane polymer coating and a tetradecanoic acid modified SiO2 deposition layer on its surface.

[0008] The aforementioned automotive paint protection film uses hyperbranched polysiloxane (HB-PDMS) as a self-healing source and a low surface energy material. Hyperbranched polysiloxane (HB-PDMS), as a viscous self-healing polymer, achieves self-healing through reversible hydrogen bonding between newly formed amide groups in the molecule. Furthermore, the relatively large molecular weight of HB-PDMS... By imparting high viscosity, it can firmly adhere to the substrate (TPU substrate). The SiO2 surface is coated with tetradecanoic acid (MA) through a condensation reaction to hydrophobically modify SiO2. Tetradecanoic acid is a type of fatty acid with a long carbon chain structure (low surface energy surfactant). The carboxyl group of tetradecanoic acid undergoes a condensation reaction with a large number of hydroxyl groups on the SiO2 surface, so that the low surface energy long carbon chain is successfully grafted onto the hydrophilic SiO2 surface, increasing the hydrophobicity. Then, the hydrophobically modified nano-SiO2 is deposited on the surface through the embedding method to construct a rough surface structure. By adopting the bottom-up design concept of "substrate + viscous self-healing polymer + hydrophobic particles", a superhydrophobic surface with self-healing function (tetradecanoic acid modified SiO2 / hyperbranched PDMS self-healing coating, i.e. MA-SiO2 / HB-PDMS coating) is obtained.

[0009] Compared to composite coatings prepared by traditional direct physical blending methods, the bottom-up coating system of "substrate + viscous self-healing polymer + hydrophobic particles" is constructed. A polymer film with viscous and self-healing functions is directly coated on the substrate, and then hydrophobic particles are deposited on its surface. The self-healing polymer at the bottom layer provides repair performance, while the hydrophobic particles at the top layer construct a surface rough structure to achieve superhydrophobic properties. This bottom-up coating system reduces interfacial defects caused by phase separation, thus inhibiting the generation of microcracks and improving the durability of the self-healing superhydrophobic coating.

[0010] In addition, compared with linear polymers, hyperbranched polymers have more terminal functional groups, which can be used to construct self-healing functions. They also have structural characteristics such as high branching and low chain entanglement, resulting in good rheological properties, eliminating the need for film-forming materials, and forming films directly on the substrate, thus improving the processability of the coating.

[0011] In the aforementioned automotive paint protection film, the thickness of the tetradecanoic acid modified SiO2 / hyperbranched PDMS self-healing coating in its layered structure is preferably selected to be 12μm-25μm; wherein, the tetradecanoic acid modified SiO2 deposition layer has a micro-nano rough structure, and is formed by the accumulation of tetradecanoic acid modified SiO2 (MA-SiO2) particles to form micron-sized clusters ranging from 1μm to 4μm.

[0012] The aforementioned automotive paint protection film, wherein the TPU substrate layer in its layered structure is preferably an aliphatic TPU substrate layer, the surface hardness is preferably 80A-93A, the visible light transmittance is preferably above 90%, the elongation at break is preferably above 300%, the haze is preferably below 2%, and the thickness is preferably 100μm-300μm.

[0013] In the aforementioned automotive paint protection film, the pressure-sensitive adhesive layer in its layered structure is preferably an acrylic pressure-sensitive adhesive layer or a polyurethane pressure-sensitive adhesive layer, the visible light transmittance is preferably above 90%, and the thickness is preferably 10μm-50μm.

[0014] The aforementioned automotive paint protection film, wherein the release film layer in its layered structure is preferably a PET release film layer, more preferably a white PET release film layer, preferably has a haze of 70% or more, preferably a release force of 20g / inch or less, and preferably has a thickness of 23μm-100μm.

[0015] The aforementioned automotive paint protection film preferably includes a protective film layer in its layered structure, which is laminated onto the surface of a tetradecanoic acid modified SiO2 / hyperbranched PDMS self-healing coating.

[0016] The protective film layer can protect the tetradecanoic acid modified SiO2 / hyperbranched PDMS self-healing coating to the greatest extent, so as to avoid the situation that "the tetradecanoic acid modified SiO2 / hyperbranched PDMS self-healing coating is scratched and worn during packaging, transportation and construction".

[0017] In the aforementioned automotive paint protection film, the protective film layer in its layered structure is preferably a PET protective film, and its thickness is preferably 12μm-75μm.

[0018] Compared with the prior art, the automotive paint protection film obtained by this utility model has the following technical effects:

[0019] The superhydrophobic surface has a self-healing function. The superhydrophobic coating has a contact angle of 152.61° and a roll-off angle of 1.9°. It has excellent anti-fouling properties. When the coating surface is damaged, scratches can be repaired by heat treatment at 80°C for 2 hours. It has excellent self-healing properties.

[0020] In addition, the superhydrophobic surface with self-healing function also has good weather resistance and mechanical stability. After undergoing 5 tape peeling tests, linear abrasion tests with a wear length of 20 cm, 50 min ultrasonic oscillation tests, 10 temperature difference cycles and 24 h of ultraviolet irradiation, the contact angle still remains above 150°. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the layered structure of a car paint protection film.

[0022] In the figure: 1. Protective film layer; 2. Tetradecanoic acid modified SiO2 / hyperbranched PDMS self-healing coating; 3. TPU substrate layer; 4. Pressure-sensitive adhesive layer; 5. Release film layer. Detailed Implementation

[0023] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present utility model are within the protection scope of the present utility model. Example 1:

[0024] like Figure 1 As shown, as one embodiment of this utility model, the automotive paint protection film provided in this embodiment has a layered structure comprising: a protective film layer 1, a tetradecanoic acid modified SiO2 / hyperbranched PDMS self-healing coating 2, a TPU substrate layer 3, a pressure-sensitive adhesive layer 4, and a release film layer 5, which are sequentially laminated; wherein, the tetradecanoic acid modified SiO2 / hyperbranched PDMS self-healing coating 2 is composed of a hyperbranched polysiloxane polymer coating and a tetradecanoic acid modified SiO2 deposition layer on its surface.

[0025] In this embodiment, the protective film layer is a PET protective film (Yihua Toray, G01) with a thickness of 12μm.

[0026] In this embodiment, the thickness of the tetradecanoic acid-modified SiO2 / hyperbranched PDMS self-healing coating is 12 μm. The tetradecanoic acid-modified SiO2 deposition layer exhibits a micro-nano rough structure, and is composed of tetradecanoic acid-modified SiO2 particles stacked to form micron-sized clusters ranging from 1 μm to 4 μm.

[0027] In this embodiment, the TPU substrate layer uses an aliphatic TPU base film (Argotec 49510) with a surface hardness of 93A, a visible light transmittance of 92%, an elongation at break of 550%, a haze of 1.0%, and a thickness of 100μm.

[0028] In this embodiment, the pressure-sensitive adhesive layer is made of acrylic pressure-sensitive adhesive (Henkel, Loctite 8087), with a visible light transmittance of 92% and a thickness of 10μm.

[0029] In this embodiment, the release film layer is a white PET release film (Toray, XZ31SR) with a haze of 73%, a release force of 10g / inch, and a thickness of 23μm.

[0030] Meanwhile, this embodiment also provides a method for preparing the aforementioned automotive paint protection film, which can employ a process of first coating a pressure-sensitive adhesive and then coating a tetradecanoic acid-modified SiO2 / hyperbranched PDMS self-healing coating. The preferred coating methods are roller coating, slot coating, or comma-blade coating. Specifically, it includes the following steps:

[0031] Step 1: Synthesis of hyperbranched polysiloxane (HB-PDMS)

[0032] Tetrahydrofuran (THF, AR, Shanghai Maclean Biotechnology Co., Ltd.) and pyridine (AR, Shanghai Aladdin Biotechnology Co., Ltd.) were pre-treated to remove water. 0.619 g of 1,3,5-benzenetricarboxylic chloride (TMC, 98%, Shanghai Aladdin Biotechnology Co., Ltd.) was dissolved in 15 mL of THF and stirred thoroughly for 30 min. 2.375 g of diaminopropyl-terminated polydimethylsiloxane (A-PDMS, weight average molecular weight M...) was also prepared. w ≈950 g / mol (Gelest, Inc.) was dissolved in dry, ice-cooled THF, 0.2 mL of pyridine was added, and the TMC / THF solution was slowly added dropwise. The reaction was carried out in an ice bath under an argon atmosphere for 2 h, followed by a reaction at 35 °C for 3 h. After the reaction was completed, the product was discharged. The synthesized polymer solution was poured into an anhydrous ethanol (EtOH, AR, Tianjin Fuyu Fine Chemical Co., Ltd.) / deionized water (V(EtOH):V(deionized water) = 1:1) mixed solution under stirring. The mixture was allowed to stand for 12 h to precipitate, and the polymer precipitated from the solution. The polymer was separated and washed with anhydrous ethanol until the supernatant was neutral to obtain hyperbranched PDMS, i.e., HB-PDMS.

[0033] Step 2: Tetradecanoic acid modified SiO2 particles (MA-SiO2)

[0034] 2 g of myristic acid (MA, 98%, Shanghai Aladdin Biochemical Technology Co., Ltd.) was dissolved in 40 mL of xylene (AR, Sinopharm Chemical Reagent Co., Ltd.), and 2 g of nano-SiO2 (particle size 50 nm, 99.5%) was added. After stirring for 3 h, the mixture was centrifuged at 8000 r / min and washed with ethanol. After drying at 60 °C, it was ground into powder to obtain MA-SiO2.

[0035] Step 3: Preparation of pressure-sensitive adhesive layer

[0036] An acrylic pressure-sensitive adhesive (Henkel, Loctite 8087) coating solution was applied to a 23 μm thick white PET release film (Toray, XZ31SR) and dried at 110°C for 2 minutes to form a 10 μm thick pressure-sensitive adhesive layer. This pressure-sensitive adhesive layer was then applied to one side of a 100 μm thick aliphatic TPU substrate (Argotec 49510).

[0037] Step 4: Preparation of MA-SiO2 / HB-PDMS coating

[0038] HB-PDMS was dissolved in THF at a concentration of 0.4 g / mL and uniformly coated on the other side of the TPU substrate. The prepared MA-SiO2 powder was sieved onto the uncured HB-PDMS coating using a 0.18 mm sieve until the surface was uniformly covered. After standing for 5 min, it was dried in an oven at 60 °C for 12 h. Finally, the excess powder on the coating surface was removed to obtain a MA-SiO2 / HB-PDMS composite coating with a thickness of 12 μm.

[0039] Step 5: Composite protective film layer

[0040] A 12μm PET protective film (Yihua Toray, G01) was applied to the MA-SiO2 / HB-PDMS coating.

[0041] Step Six: Mature

[0042] The semi-finished product from step five is placed in a 50°C curing chamber and cured for 72 hours to obtain the automotive paint protection film of this utility model. Example 2:

[0043] As a second embodiment of the present invention, the automotive paint protection film provided in this embodiment has a layered structure and preparation method that are largely the same as those in Embodiment 1.

[0044] However, in this embodiment, the PET protective film (Yihua Toray, G01) used as the protective film layer has a thickness of 45 μm. The myristate-modified SiO2 / hyperbranched PDMS self-healing coating in this embodiment has a thickness of 20 μm. The aliphatic TPU base film (Argotec 49510) used as the TPU substrate layer in this embodiment has a thickness of 200 μm. The pressure-sensitive adhesive layer in this embodiment also uses acrylic pressure-sensitive adhesive (Henkel, Loctite 8087), with a dry adhesive thickness of 30 μm. The white PET release film (Toray, XZ31SR) used as the release film layer in this embodiment has a thickness of 62 μm. Example 3:

[0045] As a third embodiment of this utility model, the automotive paint protection film provided in this embodiment has the same layered structure and preparation method as in Embodiment 1.

[0046] However, in this embodiment, the PET protective film (Yihua Toray, G01) used as the protective film layer has a thickness of 75 μm. The myristate-modified SiO2 / hyperbranched PDMS self-healing coating in this embodiment has a thickness of 25 μm. The aliphatic TPU base film (Argotec 49510) used as the TPU substrate layer in this embodiment has a thickness of 300 μm. The pressure-sensitive adhesive layer in this embodiment also uses acrylic pressure-sensitive adhesive (Henkel, Loctite 8087), with a dry adhesive thickness of 50 μm. The white PET release film (Toray, XZ31SR) used as the release film layer in this embodiment has a thickness of 100 μm.

[0047] The table below shows the test data for the static water contact angle and roll-off angle of the automotive paint protection films provided in Examples 1-3.

[0048] Example Static contact angle of water (°) Roll-off angle (°) Example 1 152.61 1.9 Example 2 152.61 1.9 Example 3 152.61 1.9

[0049] The test methods for the static contact angle and roll-off angle of water in the table above are as follows:

[0050] Select a piece of automotive paint protection film, remove the release liner and protective film, and wet-apply it to a black painted panel. Use an SDC-200S contact angle tester to test the surface water static contact angle of the automotive paint protection film. Perform 5 measurements for each sample and record the calculated values.

[0051] The self-healing, anti-fouling, weather-resistant, and mechanical stability properties of the automotive paint protection films provided in Examples 1-3 are evaluated below.

[0052] (1) Self-healing performance

[0053] Each of the automotive paint protection films prepared in each embodiment had its release film and protective film removed, and was wet-applied to a black paint panel. These were labeled as Sample 1, Sample 2, and Sample 3, respectively. Scratches were created on each sample using a blade to penetrate the surface coating without breaking the substrate. Each sample was then heat-treated, and the scratch repair process on the coating surface was observed using a metallographic microscope (CMY-310, Beijing Century Kexin Scientific Instruments Co., Ltd.).

[0054] The results showed that the scratches on each damaged sample were completely repaired after heat treatment at 80℃ for 2 h. This was because the increased temperature accelerated the migration of the underlying self-healing polymer molecular chains, and the originally broken hydrogen bonds underwent non-directional recombination with the movement of the molecular chains, thereby repairing the scratches and achieving self-healing of the coating.

[0055] (2) Antifouling performance

[0056] Each of the automotive paint protection films prepared in each embodiment had its release film and protective film removed, and was wet-applied to a black paint panel and labeled as Sample 1, Sample 2 and Sample 3 respectively. Each sample was immersed in diluted red ink to simulate dye and then removed to observe the ink residue on the sample surface.

[0057] The results showed that the surfaces of all samples were clean and free of any dye, indicating that the surface coatings of each sample had excellent anti-fouling properties. This is because the superhydrophobic coating, due to its excellent hydrophobicity, traps some air between the rough surface structures, preventing the coating from being wetted by contaminants, thus resulting in excellent anti-fouling performance.

[0058] (3) Weather resistance

[0059] During use, automotive paint protection films are exposed to the external environment for extended periods, making them susceptible to weathering and reduced coating durability. This study uses day-night temperature cycling and accelerated UV aging tests to assess the weather resistance of the automotive paint protection film surface coating, and evaluates the coating's stability by observing changes in the contact angle of the coating surface.

[0060] Each of the automotive paint protection films prepared in each embodiment had its release film and protective film removed, and was wet-applied to a black painted panel, and marked as Sample 1, Sample 2, and Sample 3 respectively. The coatings were subjected to temperature difference cycling tests using a high and low temperature humidity test chamber (PL-150, Guangdong Hongzhan Technology Co., Ltd.). One cycle consisted of maintaining the coating at −20℃ for 1 hour and then at 50℃ for 1 hour, and the cycles were repeated 10 times. The coatings were then subjected to UV aging tests by irradiating them with a 500 W high-pressure mercury lamp, and the changes in the contact angle of the coating surface were observed.

[0061] The results showed that during the 10 temperature cycle experiments, the contact angle of each sample did not change much and remained above 150°. After 10 h of ultraviolet radiation, the contact angle of each sample also did not change much and remained above 150°. This is because SiO2 is distributed in the coating, and its excellent ultraviolet absorption performance allows the MA-SiO2 / HB-PDMS coating to maintain a stable contact angle after 24 h of ultraviolet radiation, demonstrating excellent resistance to ultraviolet aging.

[0062] (4) Mechanical stability

[0063] Durability is a crucial performance indicator for automotive paint protection films. Besides weather resistance, the mechanical stability of the surface coating is also paramount. Therefore, linear abrasion resistance, tape peeling, and ultrasonic vibration tests were conducted on the prepared automotive paint protection film surface coating. The mechanical stability was assessed by evaluating the change in the contact angle of the coating surface during these tests.

[0064] Each of the automotive paint protection films prepared in the various embodiments was stripped of its release film and protective film, and then wet-applied to a black painted panel, labeled as Sample 1, Sample 2, and Sample 3 respectively. The abrasion resistance of the superhydrophobic coating was evaluated using a sandpaper abrasion test. The sample was placed on 0.013 mm sandpaper, a 200 g weight was applied, and then the sample was moved uniformly for 10 cm in a fixed direction to induce abrasion. The contact angle was measured after each abrasion to evaluate the effect of the abrasion length on its wetting properties. 3M tape was adhered to the sample surface and pressed to ensure full contact between the sample and the tape. After peeling the tape off the sample, the surface contact angle was measured to investigate the effect of the number of tape peels on its wetting properties. Ultrasonic oscillation tests were conducted using an ultrasonic cleaner (Kunshan Ultrasonic Instrument Co., Ltd.). Using ultrasound to simulate the external environment, the sample was placed in deionized water and ultrasonically sonicated for 10 min. The surface contact angle was measured after each ultrasonic sonication to investigate the effect of ultrasonic time on the sample's wetting properties.

[0065] The results showed that after a linear abrasion test with a wear length of 20 cm, the contact angles of all samples did not change significantly, remaining above 150°. Furthermore, all samples could withstand five tape peels without significant difference in contact angle changes, also remaining above 150°. The ultrasonic oscillation test results revealed that the contact angle of the surface coating on each sample changed little with increasing ultrasonic time, indicating strong adhesion between the coating and the substrate.

[0066] This utility model is not limited to the above-described preferred embodiments. Anyone can derive other forms of products under the guidance of this utility model. However, regardless of any changes made in their shape or structure, any technical solution that is the same as or similar to this application falls within the protection scope of this utility model.

Claims

1. A protective film for automotive paint, characterized by being layered. The structure includes: a tetradecanoic acid modified SiO2 / hyperbranched PDMS self-healing coating, a TPU substrate layer, a pressure-sensitive adhesive layer, and a release film layer, which are sequentially compounded; wherein, the tetradecanoic acid modified SiO2 / hyperbranched PDMS self-healing coating is composed of a hyperbranched polysiloxane polymer coating and a tetradecanoic acid modified SiO2 deposition layer on its surface.

2. The automotive paint protection film according to claim 1, characterized in that: The thickness of the tetradecanoic acid modified SiO2 / hyperbranched PDMS self-healing coating is 12μm-25μm; wherein, the tetradecanoic acid modified SiO2 deposition layer has a micro-nano rough structure, and is formed by the accumulation of tetradecanoic acid modified SiO2 particles to form micron-sized clusters ranging from 1μm to 4μm.

3. The automotive paint protection film according to claim 1, characterized in that: The TPU substrate layer is an aliphatic TPU substrate layer with a thickness of 100μm-300μm.

4. The automotive paint protection film according to claim 1, characterized in that: The pressure-sensitive adhesive layer is an acrylic pressure-sensitive adhesive layer or a polyurethane pressure-sensitive adhesive layer, with a thickness of 10μm-50μm.

5. The automotive paint protection film according to claim 1, characterized in that: The release film layer is a PET release film layer with a thickness of 23μm-100μm.

6. The automotive paint protection film according to claim 1, characterized in that: It also includes a protective film layer, which is composited onto the surface of a tetradecanoic acid modified SiO2 / hyperbranched PDMS self-healing coating.

7. The automotive paint protection film according to claim 6, characterized in that: The protective film layer is a PET protective film with a thickness of 12μm-75μm.

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