Uv-weathering resistant pvc film and its application in car body stickers

Abstract

The application discloses a PVC film resistant to ultraviolet weathering and application of the PVC film in a car body sticker, and relates to the technical field of polymer PVC car body sticker films.The PVC film resistant to ultraviolet weathering is prepared from the following raw materials in parts by mass: 100 parts of PVC resin, 30-60 parts of plasticizer, 2-5 parts of heat stabilizer, 0.5-3 parts of ultraviolet absorber, 0.2-1.5 parts of antioxidant, 5-20 parts of filler and 1-10 parts of colorant.The application optimizes the compatibility of the ultraviolet absorber with the PVC matrix through a specific novel structure, and forms a synergistic protection system by matching the heat stabilizer and the antioxidant, so that the degradation of the PVC molecular chain caused by outdoor ultraviolet irradiation can be effectively inhibited, the aging and attenuation trend of the appearance (such as discoloration, yellowing, loss of gloss, cracking and powdering) and performance of the film in long-term outdoor use is obviously slowed down, and the ultraviolet weathering resistance effect is more durable.

Description

Technical Field

[0001] This invention relates to the field of polymer PVC vehicle wrapping technology, specifically to a UV-resistant PVC wrapping film and its application in vehicle wrapping. Background Technology

[0002] PVC (polyvinyl chloride) resin is widely used in the automotive wrap industry due to its low cost, excellent processing performance, and moderate mechanical strength. The film layer made from PVC can give automotive wraps decorative and advertising functions, meeting the needs of personalized car exteriors and commercial promotion. However, automotive wraps are exposed to the outdoor environment for extended periods, and the core problem they face is ultraviolet aging—ultraviolet rays from sunlight (especially UV-B and UV-A rays in the 280-400nm range) can penetrate the PVC film surface, triggering a photo-oxidative degradation reaction of the resin molecular chains.

[0003] Specifically, ultraviolet (UV) irradiation damages the C-Cl and CC bonds in PVC molecules, leading to molecular chain breakage or cross-linking. This results in a series of aging and failure phenomena in the mask: visually, this manifests as fading, yellowing, and loss of gloss; in severe cases, surface cracking and powdering occur. Performance-wise, it is accompanied by decreased tensile strength and loss of flexibility, making the mask easily peel off the vehicle surface. This not only negates its original decorative and marking functions but also increases the difficulty of subsequent cleaning due to residual adhesive. While existing technologies improve weather resistance by adding UV absorbers and antioxidants, they have significant limitations: traditional UV absorbers (such as common benzotriazoles and benzophenones) have poor compatibility with PVC resin and are prone to precipitating onto the surface with long-term use, causing the UV resistance to decrease over time; some heat stabilizers and antioxidants are improperly combined, and under the synergistic effect of UV and high temperature, they may actually catalyze PVC degradation, further shortening the mask's lifespan.

[0004] Currently, the outdoor UV aging resistance of conventional PVC vehicle wrap films on the market is generally only 6-12 months, which is far from meeting the long-term weather resistance requirements of commercial advertising, vehicle decoration, and other scenarios. Frequent replacement not only increases usage costs but may also damage the vehicle paint due to the aging film peeling off. Therefore, developing a film formula with long-lasting, stable UV weathering resistance and excellent compatibility with PVC systems has become the key to solving the pain points of existing technologies. Summary of the Invention

[0005] To address the issues of poor UV aging resistance, poor compatibility between additives and resins leading to easy precipitation, and short outdoor lifespan (only 6-12 months) of existing PVC films, which cannot meet the long-term weather resistance requirements of vehicle wraps, a UV-resistant PVC film is provided. By optimizing the formula (containing the UV absorber shown in Formula 1), the compatibility of additives is improved, achieving long-lasting UV resistance, extending outdoor lifespan, and adapting to the application scenarios of vehicle wraps.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is: a PVC face mask resistant to ultraviolet weathering, comprising the following raw materials in parts by weight: 100 parts PVC resin, 30-60 parts plasticizer, 2-5 parts heat stabilizer, 0.5-3 parts ultraviolet absorber, 0.2-1.5 parts antioxidant, 5-20 parts filler, and 1-10 parts colorant.

[0007] The ultraviolet absorber has the structure shown in Formula 1;

[0008] Equation 1: ;

[0009] In Formula 1, R1 is a substituent and n is the number of substituents;

[0010] Where n is 0, 1, or 2;

[0011] R1 is selected from any one or more of the following: fluorine, nitro, and alkyl groups having 1-5 carbon atoms.

[0012] Furthermore, the plasticizer is any one of dioctyl phthalate, diisononyl phthalate, and dioctyl adipate.

[0013] Furthermore, the heat stabilizer is a mixture of magnesium hydroxide and antimony trioxide, with a mass ratio of 1:1.25.

[0014] Furthermore, the ultraviolet absorber is any one of the compounds shown in the following structures:

[0015] ;

[0016] ;

[0017] .

[0018] Furthermore, the antioxidant is any one of antioxidant 1010, antioxidant GM, and antioxidant BHT.

[0019] Furthermore, the filler is any one of calcium carbonate, barium sulfate, and kaolin.

[0020] Furthermore, the colorant is any one of titanium dioxide, carbon black, iron oxide pigments, phthalocyanine blue, and phthalocyanine green.

[0021] A method for preparing a UV-resistant PVC face mask includes the following steps:

[0022] a. Add the PVC resin, plasticizer, heat stabilizer, antioxidant, and filler into a high-speed mixer and mix at 90-110°C for 5-10 minutes to obtain a premix.

[0023] b. After cooling the premix to 40-50°C, add the ultraviolet absorber and mix for 5-8 minutes to obtain the mixture;

[0024] c. The mixture is melt-blended and plasticized using a twin-screw extruder, with the temperature of each section of the extruder controlled at 150-180℃;

[0025] d. The plasticized material from step c is calendered using a calender, cooled, and wound up to obtain the UV-resistant PVC face film.

[0026] Furthermore, steps a and b are performed under a nitrogen atmosphere.

[0027] A vehicle wrap includes a release paper layer, a pressure-sensitive adhesive layer, and a UV-resistant PVC film layer stacked sequentially from bottom to top, wherein the thickness of the PVC film layer is 80-150 μm.

[0028] The ultraviolet absorber molecule described in this invention achieves efficient, broad-spectrum, and long-lasting photostability through the synergistic effect of multifunctional groups such as benzotriazole, anthraquinone, phenyl, and imino (-NH-). Its core mechanism is broad-spectrum ultraviolet absorption: the benzotriazole group absorbs 280-360nm ultraviolet light (UV-B and part of UV-A), converting light energy into heat energy and restoring its initial structure; the anthraquinone group, through its large conjugated system, absorbs long-wave ultraviolet (UV-A) and visible blue light (up to 400nm), and the two are connected by chemical bonds to form a "wideband antenna," achieving full-band UVA+UVB coverage. Auxiliary mechanisms include excited-state energy quenching: the low-energy excited states of anthraquinone and phenyl can quench the triplet excited state (T1) of PVC resin or its degradation products through energy transfer mechanisms, preventing photodegradation reactions. The imino group enhances the compatibility of the molecule with the PVC matrix through polar interactions, reducing migration and precipitation (such as blooming), ensuring long-term durability. Ultimately, this multifunctional integrated design synergistically inhibits PVC photo-oxidative aging through multiple pathways such as absorption, energy conversion, and quenching, effectively preventing yellowing, embrittlement, loss of gloss, and chalking, and significantly extending the service life of outdoor PVC vehicle wraps.

[0029] This invention effectively solves the problem of easy aging of PVC masks under outdoor ultraviolet light through the precise synergistic effect of its components. Its core innovation lies in using a compound of formula 1 as a multifunctional ultraviolet absorber. This molecule achieves broad-spectrum seamless absorption in the 280-400nm ultraviolet band through the chemical bonding of benzotriazole and anthraquinone groups, and also possesses an energy transfer quenching mechanism. Simultaneously, its imino polar structure significantly improves compatibility with the PVC matrix, preventing migration and precipitation. The heat stabilizer system consists of magnesium hydroxide and antimony trioxide in a mass ratio of 1:1.25. These two components synergistically neutralize the HCl generated during degradation and inhibit autocatalytic degradation through an antimony-based crosslinking reaction. Antioxidant... (e.g., 1010, GM, BHT) internally scavenge free radicals, forming a "block and then eliminate" defense network with UV absorbers; plasticizers (DOP, DINP, DOA) promote the dispersion of additives, fillers (CaCO3, BaSO4, kaolin) enhance stability through physical barrier and migration inhibition, while rutile titanium dioxide provides UV reflection shielding, forming a dual protection with chemical absorption; stepwise low-temperature feeding, nitrogen protection, and 150-180℃ temperature-controlled extrusion process ensure the activity and uniform dispersion of components, ultimately constructing a multi-level synergistic protection system from physical reflection and chemical absorption to internal stability, significantly extending the outdoor service life of the product.

[0030] Compared with the prior art, the beneficial effects of the present invention are:

[0031] 1. Significantly improved UV resistance and long-term durability: Compared with the problems of poor compatibility between traditional UV absorbers and PVC resin and easy precipitation leading to the decay of UV resistance over time, the present invention optimizes the compatibility between a UV absorber with a specific structure (shown in Formula 1) and the PVC matrix, and forms a synergistic protection system with heat stabilizers and antioxidants. This can effectively inhibit the degradation of PVC molecular chains caused by outdoor UV radiation, so that the aging and degradation trend of the mask's appearance (such as fading, yellowing, loss of gloss, cracking, and chalking) and performance is significantly slowed down during long-term outdoor use, and the UV resistance and weathering effect is more durable.

[0032] 2. Enhanced mechanical property stability: Addressing the issue that existing PVC masks are prone to decreased tensile strength and loss of flexibility under the combined effects of ultraviolet radiation, high temperature, and humid heat, this invention, through precise component matching and optimized preparation process, ensures that the mask retains its mechanical properties (such as tensile strength) better after aging at room temperature and under heat and humidity resistance. It is less prone to embrittlement and easy peeling, and its mechanical property stability is significantly superior to existing technologies.

[0033] 3. Extended service life for vehicle wrap applications: Existing conventional PVC vehicle wrap films have a short outdoor UV aging resistance life, requiring frequent replacement and potentially damaging the vehicle paint. This invention, with its improved UV weathering resistance and mechanical stability, significantly extends the outdoor service life of the PVC film and the vehicle wraps made from it, reducing the frequency of replacement. This not only lowers usage costs but also avoids the risk of damage to the vehicle paint caused by the aging film peeling off, better meeting the long-term decorative and advertising needs of vehicle wraps. Attached Figure Description

[0034] Figure 1 This is the NMR spectrum of the ultraviolet absorber 1 described in this invention. Detailed Implementation

[0035] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] Preparation Example 1

[0037] Preparation of UV absorber 1:

[0038] .

[0039] Step 1: Add 10g of compound 1, 4.30g of compound 2, 1.64g of sodium hydroxide, and 130g of dichloromethane to the reactor. Replace the air in the reaction system three times with nitrogen. Under nitrogen protection, add 0.75g of Pd(dba)2 and 0.35g of triphenylphosphine. Replace the air in the reaction system three times again with nitrogen. Slowly raise the temperature to 100°C and react for 5 hours under nitrogen protection. After the reaction is complete, filter with diatomaceous earth, remove the solvent under reduced pressure, and finally obtain 8.68g of compound 3 (yield 76.29%) by silica gel column chromatography (using a mixed solvent of ethyl acetate and petroleum ether as the eluent).

[0040] Step 2: 8.68 g of compound 3, 11.85 g of compound 4, 0.16 g of palladium acetate, 4.80 g of triethylamine, and 110 ml of N,N-dimethylformamide were added to the reactor. After stirring until homogeneous, the mixture was reacted at 90 °C for 6 h under a nitrogen atmosphere. After the reaction was complete, the reaction mixture was cooled and filtered to remove the catalyst, the solvent was removed under reduced pressure, and finally, the mixture was subjected to silica gel column chromatography (using a mixture of ethyl acetate and petroleum ether as the eluent) to obtain 11.92 g of UV absorber 1 (yield 71.65%).

[0041] Product structure identification:

[0042] The mass spectrum of compound 3 was measured at m / z=416 using ms+1.

[0043] The mass spectrometry of UV absorber 1 was measured at m / z=701 using ms+1.

[0044] UV absorber 1 1 H NMR ( Figure 1 , Chloroform-d) δ 8.19-8.06 (m, 5H), 7.97-7.81 (m, 4H), 7.61-7.47 (m, 5H), 7.45-7.36 (m, 2H), 7.23 (m, 2H), 6.89 (d,1H), 6.72-6.62 (m, 2H), 3.95 (q, 1H), 2.81 (d, 3H).

[0045] Preparation Examples 2-6

[0046] In Preparation Examples 2-6, ultraviolet absorber 2-ultraviolet absorber 6 were prepared sequentially, following the preparation method of Preparation Example 1, except that compound 2 was replaced, and the rest remained the same as in Preparation Example 1. See Table 1 for details.

[0047] Table 1.

[0048]

[0049] Example 1

[0050] Preparation of a UV-resistant PVC face mask:

[0051] 1. Raw material composition:

[0052] PVC resin: 100 parts by weight, purchased from: Changxing Materials Industry (Guangdong) Co., Ltd.;

[0053] Plasticizer: 45 parts by weight, selected as dioctyl phthalate, purchased from: Wuhan Jiyesheng Chemical Co., Ltd.;

[0054] Heat stabilizer: 4 parts by weight, composed of 1.78 parts by weight of magnesium hydroxide and 2.22 parts by weight of antimony trioxide in a mass ratio of 1:1.25. The magnesium hydroxide and antimony trioxide were purchased from Zhejiang Xusen Flame Retardant Co., Ltd.

[0055] Ultraviolet absorber: 2 parts by weight, using ultraviolet absorber 1 prepared in Preparation Example 1;

[0056] Antioxidant: 0.8 parts by weight, using antioxidant 1010, purchased from Guangzhou Dayin New Material Co., Ltd.;

[0057] Filler: 12 parts by weight, calcium carbonate, purchased from Shanghai Nuocheng Pharmaceutical Co., Ltd.

[0058] Colorant: 5 parts by weight, rutile titanium dioxide, purchased from Nanjing Titanium Dioxide Chemical Co., Ltd.

[0059] 2. Preparation method:

[0060] a. The PVC resin, dioctyl phthalate, the mixture of magnesium hydroxide and antimony trioxide, antioxidant 1010, and light calcium carbonate are put into a high-speed mixer and mixed for 8 minutes at 100°C under nitrogen atmosphere protection to obtain a premix.

[0061] b. After cooling the premix to 45°C, add ultraviolet absorber 1 under a nitrogen atmosphere and continue mixing for 6 minutes to obtain the mixture;

[0062] c. The mixture is melt-blended and plasticized using a twin-screw extruder. The temperature of each section of the extruder is controlled as follows: Zone 1 150°C, Zone 2 165°C, Zone 3 175°C, and Die Head 180°C.

[0063] d. The plasticized material is calendered by a calender, cooled by water at 25°C, and then wound up to obtain a PVC film with a thickness of 120μm.

[0064] Examples 2-6

[0065] The preparation of a UV-resistant PVC face mask is carried out by referring to the preparation method of Example 1, except that the UV absorber is replaced with UV absorber 2-UV absorber 6 prepared in Preparation Examples 2-6, and the rest is the same as in Example 1.

[0066] Comparative Example 1

[0067] The preparation of a UV-resistant PVC face mask is carried out by referring to the preparation method of Example 1, except that the UV absorber is replaced with UV absorber UV-366 (CAS: 169198-72-5), and the rest is the same as in Example 1.

[0068] Comparative Example 2

[0069] The preparation of a UV-resistant PVC face mask is carried out by referring to the preparation method of Example 1, except that the UV absorber is replaced with UV absorber-928 (CAS: 73936-91-1), and the rest is the same as in Example 1.

[0070] Comparative Example 3

[0071] The preparation of a UV-resistant PVC face mask is the same as in Example 1, except that the UV absorber is not added.

[0072] Comparative Example 4

[0073] The preparation of a UV-resistant PVC face mask follows the same method as in Example 1, except that antimony trioxide is not added, and the rest remains the same as in Example 1.

[0074] Comparative Example 5

[0075] The preparation of a UV-resistant PVC face mask is the same as in Example 1, except that magnesium hydroxide is not added.

[0076] Comparative Example 6

[0077] The preparation of a UV-resistant PVC face mask is the same as in Example 1, except that no antioxidant is added.

[0078] Performance testing:

[0079] 1. Ultraviolet Aging Performance Test: The test was conducted according to GB / T16422.1-2019 "Laboratory Light Source Exposure Test Methods for Plastics - Part 3: Fluorescent Ultraviolet Lamps". A UVA-340nm fluorescent ultraviolet lamp (precisely simulating outdoor UV-A and UV-B bands) was used as the light source, and the irradiance was set to 0.55 W / (m²). 2 • 340nm), using a cycle of "8h irradiation + 4h condensation" (replicating outdoor day-night alternation and humid environment), with a total aging time set to 3600h. After aging, the yellowing index (YI) was measured according to GB / T 2409-2021 "Determination of Yellow Index and Whiteness of Plastics", and the color difference (ΔE) was measured using the CIE LAB system according to GB / T 7921-2008 "Uniform Color Space and Color Difference Formula". The data are shown in Table 2.

[0080] 2. Mechanical property testing: The tensile strength of the samples was tested in accordance with GB / T 1040.3-2006 "Determination of tensile properties of plastics - Part 3: Test conditions for films and sheets", and the data are shown in Table 2.

[0081] 3. Heat and oxygen aging resistance: The sample was placed in a 70℃ dark heat aging chamber for 1000h, and the tensile strength retention rate was tested after the test. The sample was placed in a humid heat chamber at 40℃ and 95% relative humidity for 1000h, and the tensile strength retention rate was tested after the test. The data are shown in Table 2.

[0082] Table 2.

[0083]

[0084] The performance indicators of the Example Group were balanced and showed little fluctuation. Yellowing and color difference were at a relatively good level, basic tensile properties were stable, and strength retention under heat and moisture conditions was also excellent. Compared with the Examples, Comparative Examples 1-2, which used different conventional UV absorbers, showed more significant yellowing and color difference, and their basic tensile properties and strength retention after heat and moisture resistance were weakened. Comparative Example 3, which did not add a UV absorber, showed the most significant yellowing and color difference, and its basic tensile properties and strength retention after heat and moisture resistance were the lowest among all groups. Comparative Examples 4-5, which lacked antimony trioxide and magnesium hydroxide respectively, showed a significantly greater decrease in strength retention under heat and moisture conditions than the Examples. Although their yellowing, color difference, and basic tensile strength were better than Comparative Example 3, they were still inferior to the Examples. Comparative Example 6, which did not add an antioxidant, showed more pronounced yellowing and color difference than the Examples, and its strength retention after heat and moisture resistance was also lower than the Examples, resulting in overall performance weaker than the Example Group.

[0085] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A PVC face mask resistant to UV weathering, characterized in that, The raw materials contain the following parts by weight: 100 parts PVC resin, 30-60 parts plasticizer, 2-5 parts heat stabilizer, 0.5-3 parts ultraviolet absorber, 0.2-1.5 parts antioxidant, 5-20 parts filler, and 1-10 parts colorant; The ultraviolet absorber has the structure shown in Formula 1; Equation 1: ; In Formula 1, R1 is a substituent and n is the number of substituents; Where n is 0, 1, or 2; R1 is selected from any one or more of the following: fluorine, nitro, and alkyl groups having 1-5 carbon atoms.

2. The UV-resistant PVC face mask according to claim 1, characterized in that, The plasticizer is any one of dioctyl phthalate, diisononyl phthalate, and dioctyl adipate.

3. The UV-resistant PVC face mask according to claim 1, characterized in that, The ultraviolet absorber is any one of the compounds shown in the following structures: ； ； 。 4. The UV-resistant PVC face mask according to claim 1, characterized in that, The antioxidant is any one of antioxidant 1010, antioxidant GM, and antioxidant BHT.

5. A UV-resistant PVC face mask according to claim 1, characterized in that, The filler is any one of calcium carbonate, barium sulfate, and kaolin.

6. A UV-resistant PVC face mask according to claim 1, characterized in that, The colorant is any one of titanium dioxide, carbon black, iron oxide pigments, phthalocyanine blue, and phthalocyanine green.

7. A method for preparing a UV-resistant PVC face mask according to any one of claims 1-6, characterized in that, Includes the following steps: a. Add the PVC resin, plasticizer, heat stabilizer, antioxidant, and filler into a high-speed mixer and mix at 90-110°C for 5-10 minutes to obtain a premix. b. After cooling the premix to 40-50°C, add the ultraviolet absorber and mix for 5-8 minutes to obtain the mixture; c. The mixture is melt-blended and plasticized using a twin-screw extruder, with the temperature of each section of the extruder controlled at 150-180℃; d. The plasticized material from step c is calendered using a calender, cooled, and wound up to obtain the UV-resistant PVC face film.

8. The method for preparing a UV-resistant PVC face mask according to claim 7, characterized in that, Steps a and b are performed under a nitrogen atmosphere.

9. A vehicle wrap, characterized in that, It includes a release paper layer, a pressure-sensitive adhesive layer, and a UV-resistant PVC film layer as described in any one of claims 1-6, stacked from bottom to top, wherein the thickness of the PVC film layer is 80-150 μm.

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