Embossing film for vehicle license plate

Abstract

The present application provides a kind of vehicle license plate with hot stamping film.The vehicle license plate with hot stamping film of the present application does not include release layer or release agent, solves the poor secondary hot stamping adhesion and other problems caused by release agent or release layer, and achieves excellent hot stamping adhesion.In addition, since the vehicle license plate with hot stamping film of the present application reduces the release layer structure, the production cost is also reduced.Furthermore, after transferring the vehicle license plate with hot stamping film of the present application to the vehicle license plate, the firmness is excellent, and also has excellent weather resistance and solvent resistance, which can adapt to harsh and complex construction environment.

Description

Technical Field

[0001] This invention relates to a hot stamping film for vehicle license plates, and more particularly to a hot stamping film for vehicle license plates that does not include a release layer or release agent. Background Technology

[0002] To address environmental concerns, vehicle license plates have switched from ink printing to hot stamping for new energy vehicles, as hot stamping is more environmentally friendly than ink printing. The hot stamping process involves using a hot stamping machine to soften and adhere the stamped layer to the substrate using the temperature and pressure of rollers in a short time.

[0003] Hot stamping film consists of two layers: a PET film as the base material and a stamping layer that is ultimately stamped onto the vehicle license plate. The side of the stamping layer closest to the base material (PET) is softened by heat and separates from it, while the adhesive layer on the opposite side is softened by heat and bonded to the license plate. The stamping layer bonded to the license plate remains on the plate, while the other layers remain on the base film. Vehicle license plates use reflective film, which varies in surface layer depending on the manufacturer; it can be PVC, acrylic, PU, ​​etc. For ease of processing, vehicle license plate manufacturers generally keep the stamping film unchanged, while using different models of reflective film for the license plate itself.

[0004] Due to the requirements of the hot stamping process, the hot stamping layer needs to be separated from the substrate layer during hot stamping. Therefore, in order to facilitate hot stamping of vehicle license plates and ensure that the hot stamping film can be easily separated from the substrate, a release layer is usually provided. Currently, the release layer and a transparent protective layer are typically combined.

[0005] Patent Document 1 discloses a heat transfer film for motor vehicle license plates, its manufacturing method, and its application. The film includes a PET base film layer and a heat transfer layer, which are interconnected. The heat transfer layer comprises a release layer, a color layer, and an adhesive layer connected in sequence. The release layer is made of thermoplastic acrylic resin A, polyethylene wax paste, ultraviolet absorber, and light stabilizer. The color layer is made of pigment, vinyl chloride-vinyl acetate-vinyl alcohol terpolymer, dispersant, and acrylic resin B. The adhesive layer is made of chlorinated polypropylene resin, chlorovinyl acetate resin, phenolic resin, and silica powder. Patent Document 1, through this design, enables the heat transfer film to be hot-stamped at low temperatures, resulting in high production efficiency, high hot-stamping adhesion, high hot-stamping stability, and low hot-stamping energy consumption. However, Patent Document 1 does not disclose that hot-stamping can be achieved with only two layers besides the base film layer, i.e., only the pigment layer and the hot-stamping adhesive layer are needed to achieve hot-stamping and meet the performance requirements of motor vehicle license plates.

[0006] Patent Document 2 discloses a heat transfer film comprising a substrate and a lubricating layer and a heat transfer layer respectively disposed on both sides thereof; the heat transfer layer, from near the substrate to far away from the substrate, consists of an inner coating layer, a cross-linking curing layer, a color layer, and a top coating layer; the inner coating layer comprises ethylene-hydroxyethyl acrylate copolymer, styrene-maleic anhydride copolymer, polytetrafluoroethylene wax micropowder, and an antioxidant; the cross-linking curing layer comprises melamine-formaldehyde resin, polyether polyol, and silica matting agent; the color layer comprises terpene phenolic resin, hydrogenated petroleum resin, and carbon black; and the top coating layer comprises high-chlorinated polyethylene resin, styrene-butadiene-styrene block copolymer, and asphalt. Vehicle license plates made using the heat transfer film of Patent Document 2 are strong and reliable, possess excellent weather resistance and chemical resistance, and can adapt to various harsh and complex construction environments. However, Patent Document 2 does not disclose that two layers can achieve hot stamping, i.e., only the pigment layer and the hot stamping adhesive layer other than the base film layer can achieve hot stamping and meet the performance requirements of motor vehicle license plates.

[0007] Existing technical documents

[0008] Patent documents

[0009] Patent Document 1: CN115339254A

[0010] Patent Document 2: CN112852247B Summary of the Invention

[0011] The problem the invention aims to solve

[0012] The heating method in hot stamping primarily involves wrapping a metal roller with rubber, heating the rubber either externally or internally. However, different hot stamping machine manufacturers use different processes, resulting in differences between the actual heating temperature and the final temperature. In particular, as the rubber ages, its hardness changes, and its heat transfer efficiency decreases, which affects the hot stamping process.

[0013] Therefore, some minor imperfections may exist in existing hot stamping processes. Sometimes, these minor imperfections require two hot stamping cycles to cover them up. However, current hot stamping films typically use release agents to facilitate release from the substrate layer. The release agents used can lead to poor adhesion during the second hot stamping cycle.

[0014] This invention addresses the aforementioned problems and aims to provide a hot stamping film for vehicle license plates that does not include a release layer or release agent. This solves the problems of poor adhesion during secondary hot stamping caused by the presence of release agents or release layers, achieving excellent hot stamping adhesion. Furthermore, the reduced release layer structure in this invention also lowers production costs. Even without a release layer, this invention's hot stamping film for vehicle license plates exhibits excellent abrasion resistance.

[0015] Solution for solving the problem

[0016] In order to solve the above-mentioned problems, the inventors conducted in-depth research and found that by making the hot stamping film for vehicle license plates free of release layer or release agent, the hot stamping film for vehicle license plates obtained therefrom can solve the above-mentioned problems, thereby completing the present invention.

[0017] That is, the present invention is as follows.

[0018] [1]. A hot stamping film for vehicle license plates, wherein the hot stamping film for vehicle license plates comprises: a substrate layer, a color layer disposed on one side of the substrate layer, and an adhesive layer disposed on the side of the color layer opposite to the substrate layer.

[0019] The hot stamping film for vehicle license plates does not include a release layer or release agent.

[0020] [2]. The hot stamping film for vehicle license plates according to [1], wherein the substrate layer satisfies one or more of the following conditions:

[0021] (1) The substrate layer is a polyethylene terephthalate substrate layer;

[0022] (2) The thickness of the substrate layer is 16 to 30 μm.

[0023] [3]. The hot stamping film for vehicle license plates according to [1] or [2], wherein the color layer satisfies one or more of the following conditions:

[0024] (a) The color layer is formed from a color composition comprising a resin and a colorant;

[0025] (b) The resin comprises vinyl chloride vinyl acetate copolymer.

[0026] The vinyl chloride vinyl acetate copolymer has a weight-average molecular weight of 10,000 to 150,000, a glass transition temperature of below 80°C, and a softening point of less than 100°C.

[0027] (c) The colorant comprises pigment colorants or dye colorants;

[0028] (d) The color composition further comprises at least one selected from surfactants, dispersants, defoamers, organic solvents and talc;

[0029] (e) The thickness of the color layer is 0.5 to 10 μm.

[0030] [4]. The hot stamping film for vehicle license plates according to [1] or [2], wherein the adhesive layer satisfies one or more of the following conditions:

[0031] (i) The adhesive layer is formed from an adhesive layer composition comprising at least one selected from adhesives, organic solvents, resins and colorants;

[0032] (ii) The adhesive comprises thermoplastic acrylic acid.

[0033] The thermoplastic acrylic acid has a weight-average molecular weight of 1,000 to 100,000, a glass transition temperature of below 80°C, a softening point of above 100°C, a hydroxyl value of 7 to 13 mg KOH / g, and an acid value of 17 to 23 mg KOH / g.

[0034] (iii) The organic solvent comprises ethyl acetate;

[0035] (iv) The resin comprises a non-crystalline polyester and / or vinyl chloride vinyl acetate copolymer.

[0036] The amorphous polyester has a weight-average molecular weight of 10,000 to 100,000, a glass transition temperature of below 30°C, a hydroxyl value of 5 to 11 mgKOH / g, and an acid value of less than 2 mgKOH / g.

[0037] (v) The thickness of the adhesive layer is 0.5 to 10 μm.

[0038] [5]. A method for manufacturing a hot stamping film for vehicle license plates according to any one of [1] to [4], wherein the manufacturing method includes:

[0039] Process A: Apply the color composition to the substrate layer and dry to form a color layer;

[0040] Step B: Apply the adhesive composition onto the color layer and dry to form an adhesive layer.

[0041] [6]. The manufacturing method according to claim 5, wherein,

[0042] In process A, the drying temperature is 60–120°C, and the drying time is 0.5–5 min.

[0043] In step B above, the drying temperature is 60-120℃ and the drying time is 0.5-5 min.

[0044] [7]. The manufacturing method according to [5] or [6], wherein the color composition comprises at least one selected from resin, colorant, surfactant, dispersant, defoamer, organic solvent and talc;

[0045] The adhesive composition comprises at least one selected from adhesives, organic solvents, resins, and colorants.

[0046] [8]. A method for manufacturing a vehicle license plate, comprising: hot stamping with a hot stamping film for vehicle license plates according to any one of [1] to [4].

[0047] [9]. Use of hot stamping film for vehicle license plates according to any one of [1] to [4] in improving the hot stamping adhesion and / or abrasion resistance in the manufacture of vehicle license plates.

[0048] The effects of the invention

[0049] The hot stamping film for vehicle license plates of the present invention does not include a release layer or release agent, thus solving the problems such as poor adhesion of secondary hot stamping caused by the presence of release agents or release layers, and achieving excellent hot stamping adhesion. Furthermore, since the hot stamping film for vehicle license plates of the present invention reduces the release layer structure, production costs are also reduced. In addition, the hot stamping film for vehicle license plates of the present invention exhibits excellent abrasion resistance even without a release layer.

[0050] After the vehicle license plate is transferred to the vehicle license plate using the hot stamping film of the present invention, it has excellent adhesion and also has excellent weather resistance, solvent resistance and abrasion resistance, and can adapt to harsh and complex construction and application environments. Attached Figure Description

[0051] Figure 1 This is a cross-sectional view schematically illustrating the structure of the hot stamping film for vehicle license plates according to the present invention.

[0052] Figure 2 This is a photograph showing the abrasion resistance results of the hot stamping film of Example 1.

[0053] Figure 3 This is a photograph showing the abrasion resistance results of the hot stamping film in Comparative Example 1.

[0054] Explanation of reference numerals in the attached figures

[0055] 10. Hot stamping film for vehicle license plates

[0056] 1. Substrate layer

[0057] 2 Color Layers

[0058] 3. Adhesive layer Detailed Implementation

[0059] The present invention will now be described in detail. The descriptions of the technical features described below are based on representative embodiments and specific examples of the present invention, but the present invention is not limited to these embodiments and specific examples. It should be noted that:

[0060] In this specification, the range of values ​​referred to as "value A to value B" refers to the range including the endpoint values ​​A and B.

[0061] In this specification, the numerical range indicated by "above" or "below" refers to the numerical range that includes the stated number.

[0062] In this specification, the word "may" has two meanings: to perform a certain process and not to perform a certain process.

[0063] In this specification, the terms "optional" or "optional" are used to indicate the use or omission of certain substances, components, procedures, application conditions, etc.

[0064] In this specification, the terms "substantially" and "essentially" are used to indicate that the standard deviation from the theoretical model, theoretical data, or target data is within a range of 5%, preferably 3%, and more preferably 1%.

[0065] In this specification, the terms “comprising” and / or “including” are used to indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0066] In this specification, references to "some specific / preferred embodiments," "other specific / preferred embodiments," "implementation," etc., refer to specific elements (e.g., features, structures, properties, and / or characteristics) related to that embodiment, which are included in at least one of the embodiments described herein and may or may not be present in other embodiments. Furthermore, it should be understood that these elements may be combined in any suitable manner in various embodiments.

[0067] <Hot stamping film for vehicle license plates>

[0068] In a first aspect of the present invention, a hot stamping film for vehicle license plates is provided, comprising: a substrate layer, a color layer disposed on one side of the substrate layer, and an adhesive layer disposed on the side of the color layer opposite to the substrate layer, wherein the hot stamping film for vehicle license plates does not include a release layer or release agent.

[0069] The vehicle described in this invention can be a motor vehicle, a non-motor vehicle, or other vehicles with various specific functions.

[0070] In some preferred embodiments, the vehicle of the present invention refers to a motor vehicle, including motor vehicles powered by petrochemical energy and motor vehicles powered by new energy (hydrogen energy, lithium battery, hybrid power).

[0071] In this invention, by eliminating the release layer or release agent from the hot stamping film for vehicle license plates, the problems such as poor adhesion of secondary hot stamping caused by the presence of release agents or release layers are solved, achieving excellent hot stamping adhesion. Furthermore, since the hot stamping film for vehicle license plates of this invention reduces the release layer structure, production costs are also lowered. In addition, the hot stamping film for vehicle license plates of this invention exhibits excellent abrasion resistance even without a release layer.

[0072] In some preferred embodiments, the hot stamping film for vehicle license plates of the present invention consists only of a substrate layer, a color layer, and an adhesive layer.

[0073] Figure 1 This is a cross-sectional view schematically illustrating the structure of a hot stamping film for vehicle license plates according to one embodiment of the present invention. Figure 1 As shown, the hot stamping film 10 for vehicle license plates includes: a substrate layer 1, a color layer 2 disposed on one side of the substrate layer 1, and an adhesive layer 3 disposed on the side of the color layer 2 opposite to the substrate layer 1.

[0074] In some preferred embodiments, the color layer 2 is preferably disposed on the entire surface of the substrate layer 1, and the adhesive layer 3 is preferably disposed on the entire surface of the color layer 2.

[0075] (Substrate layer)

[0076] The substrate layer serves as the carrier for the hot stamping film used for vehicle license plates, providing protection and support.

[0077] In some preferred embodiments, the substrate layer is preferably a polyethylene terephthalate (PET) substrate layer.

[0078] In some preferred embodiments, the thickness of the substrate layer is 16–30 μm, preferably 19–25 μm. If the thickness of the substrate layer is less than 16 μm, wrinkling is likely to occur during hot stamping heating, resulting in poor stamping properties and inability to provide good mechanical properties and weather protection. If the thickness of the substrate layer is greater than 30 μm, it will affect the hot stamping temperature, slow down heat transfer, and worsen the stamping properties.

[0079] In some specific implementations, the thickness of the substrate layer is 16μm, 17μm, 18μm, 19μm, 20μm, 21μm, 22μm, 23μm, 24μm, 25μm, 26μm, 27μm, 28μm, 29μm or 30μm.

[0080] The surface of the substrate layer can be optionally treated as needed. Examples of such surface treatments include matte finishing. From the viewpoint of the weather resistance of the hot stamping film surface, matte finishing is preferred for the substrate layer surface.

[0081] (Color layer)

[0082] Color layers are used to achieve specified colors.

[0083] In some preferred embodiments, the color layer is formed from a color composition.

[0084] In some preferred embodiments, the color composition comprises a resin and a colorant.

[0085] Examples of resins include vinyl chloride vinyl acetate copolymers and acrylic resins. Vinyl chloride vinyl acetate copolymers are preferred due to their suitability for coloring and the dispersibility of the colorant during coloring.

[0086] The weight-average molecular weight of the vinyl chloride-vinyl acetate copolymer is preferably 10,000 to 150,000, the glass transition temperature (Tg) is preferably below 80°C, more preferably 59 to 79°C, and even more preferably 69°C, and the softening point is preferably less than 100°C. When the above-mentioned vinyl chloride-vinyl acetate copolymer is used as the resin in the color layer, it can effectively encapsulate the colorant and give the color layer better solvent resistance, thereby further improving the stability of the hot stamping film.

[0087] As a coloring agent, it can be a pigment or dye. As a pigment or dye coloring agent, it can be as follows:

[0088] Yellow: Coloring agents of isoindoline, isoindoline, quinoline, anthraquinone, pyrazolone, flavanone, benzimidazolone, nickel azo, etc.

[0089] Red: Coloring agents of anthraquinone, dinaphthalene, quinacrine, indigo, etc.

[0090] Blue: Coloring agents such as phthalocyanine, styrax, anthraquinone, and cobalt.

[0091] Green: Colorants such as phthalocyanine, emerald green, chromium oxide, and cadmium.

[0092] Brown: Iron oxide series coloring agent, or a combination of isoindole ketone series yellow coloring agent, naphthalene-benzene series red coloring agent and phthalocyanine series blue coloring agent;

[0093] Orange: Single color can be anthraquinone, pyrazolone, violet ketone, naphthalene-benzene, quinacrine, or isoindoleone yellow colorant and naphthalene-benzene red colorant can be used together;

[0094] White: Colorants based on phthaloyl, zinc, lead, etc.

[0095] Black: Colorants such as carbon black, aniline black, dinaphthalene-impregnated benzene black, and titanium black.

[0096] In some preferred embodiments, the color composition preferably further comprises at least one selected from surfactants, dispersants, defoamers, organic solvents, and talc.

[0097] Examples of surfactants include sodium dizinc sulfosuccinate.

[0098] Examples of organic solvents include cyclohexanone.

[0099] In some preferred embodiments, based on 100 parts by weight of the total composition of the color composition, the content of resin is 12 to 48 parts by weight, the content of colorant is 12 to 48 parts by weight, the content of surfactant is 0.1 to 3 parts by weight, the content of dispersant is 0.1 to 3 parts by weight, the content of defoamer is 0 to 3 parts by weight, the content of organic solvent is 39 to 75 parts by weight, and the content of talc is 0 to 3 parts by weight.

[0100] By setting the content of the above-mentioned components in the color composition within the above-mentioned range, the color of the color layer can be made more uniform, and the hot stamping film has excellent transfer characteristics and imprint appearance in the transfer process, as well as excellent solvent resistance.

[0101] In some preferred embodiments, the thickness of the color layer is preferably 0.5–10 μm, more preferably 1–8 μm, and even more preferably 1.5–5 μm. If the thickness of the color layer is less than 0.5 μm, the hiding power is insufficient and the solvent resistance is poor. If the thickness of the color layer is greater than 10 μm, it is easy to cause the hot stamping temperature to be too high, resulting in poor transfer characteristics and imprint appearance.

[0102] In some specific implementations, the thickness of the color layer is 0.5μm, 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm or 10μm.

[0103] (Adhesive layer)

[0104] In this invention, the adhesive layer is preferably formed from an adhesive layer composition.

[0105] In some preferred embodiments, the adhesive layer composition comprises an adhesive.

[0106] Examples of adhesives include thermoplastic acrylic, EVA hot melt adhesive, PA hot melt adhesive, TPU hot melt adhesive, and PES hot melt adhesive. These can be used alone or in combination of two or more.

[0107] In some preferred embodiments, the thermoplastic acrylic acid preferably has a weight-average molecular weight of 1000 to 100000, a glass transition temperature (Tg) preferably below 80°C, more preferably 53 to 73°C, and even more preferably 63°C, a softening point preferably greater than 100°C, a hydroxyl value preferably 7 to 13 mgKOH / g, more preferably 10 mgKOH / g, and an acid value preferably 17 to 23 mgKOH / g, more preferably 20 mgKOH / g. By using the above-mentioned thermoplastic acrylic acid, the adhesive properties and hot stamping properties can be improved.

[0108] In some preferred embodiments, the adhesive composition further comprises a resin, a colorant, and an organic solvent.

[0109] Examples of resins include amorphous polyesters and vinyl chloride-vinyl acetate copolymers.

[0110] In some preferred embodiments, the weight-average molecular weight of the amorphous polyester is preferably 10,000 to 100,000, the glass transition temperature (Tg) is preferably below 30°C, more preferably 3 to 20°C, and even more preferably 8°C, the hydroxyl value is preferably 5 to 11 mgKOH / g, more preferably 8 mgKOH / g, and the acid value is preferably less than 2 mgKOH / g. By using the above-mentioned amorphous polyester, the adhesion of the adhesive layer and the hot stamping performance can be improved.

[0111] As vinyl chloride vinyl acetate and colorant, for example, the vinyl chloride vinyl acetate and colorant described in the above-described color layer can be used.

[0112] Examples of organic solvents include ethyl acetate (EAC).

[0113] In some preferred embodiments, based on 100 parts by weight of the total composition of the adhesive layer, the content of the adhesive is 10 to 90 parts by weight, the content of the organic solvent is 10 to 90 parts by weight, the content of the resin is 0 to 60 parts by weight, and the content of the colorant is 0 to 1.5 parts by weight.

[0114] By setting the content of the above-mentioned components in the adhesive composition within the above-mentioned range, excellent adhesive properties can be provided, providing sufficient adhesive force for vehicle license plates.

[0115] In some preferred embodiments, the thickness of the adhesive layer is preferably 0.5–10 μm, more preferably 1–8 μm, and even more preferably 1.5–5 μm. If the thickness of the adhesive layer is less than 0.5 μm, the adhesion is too low and cannot provide suitable adhesion. If the thickness of the adhesive layer is greater than 10 μm, it is easy to cause the hot stamping temperature to be too high, resulting in poor transfer characteristics and imprint appearance.

[0116] In some specific implementations, the thickness of the adhesive layer is 0.5μm, 1μm, 2μm, 3μm, 4μm, 5μm, 6μm, 7μm, 8μm, 9μm or 10μm.

[0117] <Manufacturing Method of Hot Stamping Film for Vehicle License Plates>

[0118] In a second aspect of the present invention, a method for manufacturing a hot stamping film for vehicle license plates is provided, comprising:

[0119] Process A: Apply the color composition to the substrate layer and dry to form a color layer;

[0120] Step B: Apply the adhesive composition onto the above color layer and dry to form an adhesive layer.

[0121] Coating methods include, for example, multi-coating machines, die coating machines, gravure coating machines, applicators, bar coating machines, air knife coating, reverse roller coating, lip coating, dip coating, offset printing, flexographic printing, gravure printing, screen printing, etc.

[0122] Examples of drying methods include, for instance, heat drying.

[0123] In step A above, the drying temperature is preferably 60-120℃, and the drying time is preferably 0.5-5 min.

[0124] In step B above, the drying temperature is preferably 60-120℃, and the drying time is preferably 0.5-5 min.

[0125] The color composition described in the above-described color layer and the adhesive composition described in the above-described adhesive layer can be used as the color composition and the adhesive composition described in the above-described adhesive layer.

[0126] <Method for Manufacturing Vehicle License Plates>

[0127] In a third aspect of the present invention, a method for manufacturing a vehicle license plate is provided, comprising: hot stamping using a hot stamping film for vehicle license plates of the present invention.

[0128] In some preferred embodiments, a hot stamping machine is used to stamp the hot stamping film for vehicle license plates.

[0129] In some preferred embodiments, the hot stamping machine operates at a speed of 1–10 m / min, preferably 2–5 m / min. Assuming the vehicle license plate thickness is greater than 1.1 mm, the distance between the upper rubber heating roller and the lower metal roller is 0.7–1 mm. The hot stamping temperature is 130–250 °C, preferably 180–200 °C. These temperatures are not equipment setpoints, but rather the surface temperature of the rubber roller before hot stamping, and the temperature remains stable during the hot stamping process.

[0130] <Applications of hot stamping film for vehicle license plates in improving the adhesion and / or abrasion resistance of hot stamping in the manufacture of vehicle license plates>

[0131] In a fourth aspect of the invention, the use of a hot stamping film for vehicle license plates is provided to improve the hot stamping adhesion and / or abrasion resistance in the manufacture of vehicle license plates.

[0132] Example

[0133] The embodiments of the present invention will be described in detail below with reference to examples. However, those skilled in the art will understand that the following examples are for illustrative purposes only and should not be considered as limiting the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer are followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products.

[0134] Example 1

[0135] The substrate is 20μm thick matte PET manufactured by DuPont in Foshan, Guangzhou.

[0136] A resin compound for the color layer was prepared by mixing and stirring 30 parts by weight of vinyl chloride vinyl acetate copolymer, 15 parts by weight of color masterbatch (Black L0080), 0.1 parts by weight of sodium dizinc sulfosuccinate, 0.1 parts by weight of dispersant (Lubrizol 32500), 0.1 parts by weight of defoamer (BYK 052), 0.1 parts by weight of talc, and 54.6 parts by weight of cyclohexanone as a solvent. The resin compound was then coated onto the PET layer. After drying at 100°C for 5 minutes, a color layer with a thickness of 2 μm was formed.

[0137] 30 parts by weight of thermoplastic acrylic acid and 70 parts by weight of ethyl acetate (EAC) as a solvent were mixed and dissolved to prepare a resin compound for the adhesive layer. This resin compound was then coated onto the aforementioned color layer. After drying at 100°C for 5 minutes, an adhesive layer with a thickness of 2 μm was formed, thus creating a hot stamping film for vehicle license plates. The evaluation results are shown in Table 1.

[0138] Example 2

[0139] The substrate is 20μm thick matte PET manufactured by DuPont in Foshan, Guangzhou.

[0140] A resin compound for the color layer was prepared by mixing and stirring 30 parts by weight of vinyl chloride vinyl acetate copolymer, 15 parts by weight of color masterbatch (Black L0080), 0.1 parts by weight of sodium dizinc sulfosuccinate, 0.1 parts by weight of dispersant (Lubrizol 32500), 0.1 parts by weight of defoamer (BYK 052), 0.1 parts by weight of talc, and 54.6 parts by weight of cyclohexanone as a solvent. The resin compound was then coated onto the PET layer. After drying at 100°C for 5 minutes, a color layer with a thickness of 2 μm was formed.

[0141] 25 parts by weight of thermoplastic acrylic acid, 5 parts by weight of amorphous polyester (VYLON resin, manufactured by Toyobo Co., Ltd., Japan), and 70 parts by weight of ethyl acetate (EAC) as a solvent were mixed, dissolved, and stirred to prepare a resin compound for the adhesive layer. This resin compound was then coated onto the aforementioned color layer. After drying at 100°C for 5 minutes, an adhesive layer with a thickness of 2 μm was formed, thus creating a hot stamping film for vehicle license plates. The evaluation results are shown in Table 1.

[0142] Example 3

[0143] The substrate is 20μm thick matte PET manufactured by DuPont in Foshan, Guangzhou.

[0144] A resin compound for the color layer was prepared by mixing and stirring 30 parts by weight of vinyl chloride vinyl acetate copolymer, 15 parts by weight of color masterbatch (Black L0080, manufactured by BASF AG), 0.1 parts by weight of sodium dizinc sulfosuccinate, 0.1 parts by weight of dispersant (Lubrizol 32500), 0.1 parts by weight of defoamer (BYK 052), 0.1 parts by weight of talc, and 54.6 parts by weight of cyclohexanone as a solvent. This resin compound was then coated onto the PET layer. After drying at 100°C for 5 minutes, a color layer with a thickness of 2 μm was formed.

[0145] 25 parts by weight of thermoplastic acrylic acid, 5 parts by weight of amorphous polyester (VYLON resin, manufactured by Toyobo Co., Ltd., Japan), 3 parts by weight of vinyl chloride-vinyl acetate copolymer, 1.5 parts by weight of colorant (Black L 0080, manufactured by BASF AG), and 65.5 parts by weight of ethyl acetate (EAC) as solvent were mixed, dissolved, and stirred to prepare a resin compound for the adhesive layer. This resin compound was then coated onto the aforementioned color layer. After drying at 100°C for 5 minutes, an adhesive layer with a thickness of 2 μm was formed, thus creating a hot stamping film for vehicle license plates. The evaluation results are shown in Table 1.

[0146] Comparative Example 1

[0147] A 21 μm thick biaxially oriented polyethylene terephthalate (PET) film was used as the substrate. A release layer (acrylic-modified silicone resin, with a silicone content of 20% and a thickness of 0.1 μm, purchased from Wacker Chemie (China) Co., Ltd.) was coated on one side of the substrate and dried for later use.

[0148] Toluene and isopropanol were mixed in a volume ratio of 3:1 to obtain a mixed solvent. This mixed solvent was used to dissolve a mixture of the following raw materials by weight percentage: 18.75% ethylene-hydroxyethyl acrylate copolymer, 75% styrene-maleic anhydride copolymer, 2.5% polytetrafluoroethylene wax micropowder, and 3.75% BHT antioxidant, to prepare an inner coating composition. The amount of mixed solvent used was 4 / 5 of the total mass of the ethylene-hydroxyethyl acrylate copolymer and the styrene-maleic anhydride copolymer. This inner coating composition was then applied to the other surface of the substrate and dried at 120°C to form an inner coating with a thickness of 2 μm.

[0149] A crosslinking and curing layer composition was prepared by dissolving a mixture of raw materials with the following weight percentages: 44% melamine-formaldehyde resin, 55% polyether polyol, and 1% silica matting agent, using methyl ethyl ketone (MEK). The amount of MEK used was 4 / 9 of the total mass of the melamine-formaldehyde resin and polyether polyol. This crosslinking and curing layer composition was then applied to the aforementioned inner coating layer and dried at 100°C to form a crosslinking and curing layer with a thickness of 1 μm.

[0150] A color layer composition was prepared by dissolving a mixture of raw materials with the following weight percentages: 36% terpene phenolic resin, 36% hydrogenated petroleum resin, and 28% carbon black, using toluene, wherein the amount of toluene was 2.5 times the total mass of the terpene phenolic resin and hydrogenated petroleum resin. The color layer composition was then coated onto the aforementioned cross-linked cured layer and dried at 100°C to form a color layer with a thickness of 2 μm.

[0151] A topcoat composition was prepared by dissolving a mixture of raw materials in the following weight percentages: 39% highly chlorinated polyethylene resin, 28% styrene-butadiene-styrene block copolymer, and 33% bitumen, using toluene, wherein the amount of toluene was 2 / 3 of the total mass of the highly chlorinated polyethylene resin, styrene-butadiene-styrene block copolymer, and bitumen. The topcoat composition was then applied onto the aforementioned color layer and dried at 120°C to form a topcoat with a thickness of 1 μm.

[0152] The aforementioned inner coating layer, cross-linked curing layer, color layer, and top coating layer constitute a heat transfer layer, thereby forming a heat transfer film for vehicle license plates.

[0153] <Evaluation Experiment>

[0154] Using L8512 series reflective film from Enshiai (Hangzhou) Film Co., Ltd., the license plate design was stamped onto an aluminum plate using Chinese license plate stamping characters. Then, a UTSCH hot stamping machine from Germany was used for hot stamping at a speed of 4 m / min. The gap between the metal roller and the rubber roller of the hot stamping machine was 1.8 mm (the height of the stamped license plate was 2 mm). Hot stamping was performed at three conditions: 150℃, 170℃, and 190℃. The results were then evaluated according to the GAT 1083-2013 standard, "Hot Stamping Film for Motor Vehicle License Plates." The rating was based on a five-point scale (1-5 points), with higher scores indicating better results, and 1 being the worst and 5 the best.

[0155] Imprint appearance:

[0156] The characters and borders transferred to the license plate surface after hot stamping should have neat and burr-free edges, and the color of the printed surface should be uniform. There should be no obvious defects such as peeling, curling, wrinkles, particulate impurities, or missing prints.

[0157] The evaluation will be conducted according to the following scoring criteria: the score is on a five-point scale (1-5 points), the higher the score, the better the evaluation result, with 1 being the worst and 5 being the best.

[0158] Adhesion performance:

[0159] After the adhesive tape peeling test, the imprint should not show any peeling or curling.

[0160] The evaluation will be conducted according to the following scoring criteria: the score is on a five-point scale (1-5 points), the higher the score, the better the evaluation result, with 1 being the worst and 5 being the best.

[0161] Solvent resistance:

[0162] Immerse the license plate samples in SAE40 lubricating oil, -20 diesel oil, and gasoline of 70 or higher for 30 minutes each, then remove, wipe dry, and let stand for 1 hour. After the test, the imprint should not show any fading, discoloration, color loss, softening, wrinkling, blistering, cracking, layering, curling, or signs of dissolution.

[0163] The evaluation will be conducted according to the following scoring criteria: the score is on a five-point scale (1-5 points), the higher the score, the better the evaluation result, with 1 being the worst and 5 being the best.

[0164] Table 1

[0165]

[0166] As can be seen from Table 1, the hot stamping films of Examples 1 to 3 not only have excellent hot stamping properties, but also excellent hot stamping adhesion, which can solve the problems such as poor adhesion of secondary hot stamping caused by release agent or release layer, and also have excellent solvent resistance.

[0167] In addition, the hot stamping film of Example 1 and the hot stamping film of Comparative Example 1 were evaluated for abrasion resistance as follows: using a TABER tester CS-10 grinding wheel, the hot stamping film of Example 1 or the hot stamping film of Comparative Example 1 was placed under the grinding wheel and subjected to 100 cycles of abrasion test at a rotation speed of 30 r / min using the TABER tester.

[0168] like Figure 2 As shown, the hot stamping film of Example 1, even without the release layer, did not show any white showing after 100 cycles of abrasion testing, demonstrating excellent abrasion resistance and making it widely applicable to environments such as harsh cleaning environments or frequent cleaning.

[0169] And such Figure 3 As shown, the hot stamping film of Comparative Example 1 showed obvious whitening after 100 cycles of abrasion test, indicating poor abrasion resistance and unsuitability for environments such as harsh cleaning environments or frequent cleaning.

[0170] Industrial availability

[0171] The hot stamping film for vehicle license plates of the present invention does not include a release layer or release agent, thus solving the problems such as poor adhesion of secondary hot stamping caused by the presence of release agents or release layers, and achieving excellent hot stamping adhesion. Furthermore, since the hot stamping film for vehicle license plates of the present invention reduces the release layer structure, production costs are also reduced. In addition, the hot stamping film for vehicle license plates of the present invention exhibits excellent abrasion resistance even without a release layer. After being transferred onto a vehicle license plate, the hot stamping film for vehicle license plates of the present invention exhibits excellent adhesion, as well as excellent weather resistance, solvent resistance, and abrasion resistance, making it adaptable to harsh and complex construction and application environments.

Claims

1. A hot stamping film for vehicle license plates, characterized in that, The hot stamping film for vehicle license plates includes: a substrate layer, a color layer disposed on one side of the substrate layer, and an adhesive layer disposed on the side of the color layer opposite to the substrate layer. The hot stamping film for vehicle license plates does not include a release layer or release agent. The thickness of the substrate layer is 16~30μm. The adhesive layer is formed from an adhesive layer composition. The adhesive layer composition contains an adhesive. The adhesive comprises thermoplastic acrylic. The thermoplastic acrylic acid has a weight-average molecular weight of 1,000 to 100,000, a glass transition temperature below 80°C, a softening point above 100°C, a hydroxyl value of 7 to 13 mg KOH / g, and an acid value of 17 to 23 mg KOH / g.

2. The hot stamping film for vehicle license plates according to claim 1, characterized in that, The substrate layer satisfies the following conditions: (1) The substrate layer is a polyethylene terephthalate substrate layer.

3. The hot stamping film for vehicle license plates according to claim 1 or 2, characterized in that, The color layer is formed from a color composition comprising a resin and a colorant; the color layer also satisfies one or more of the following conditions: (b) The resin comprises a vinyl chloride-vinyl acetate copolymer. The vinyl chloride vinyl acetate copolymer has a weight-average molecular weight of 10,000 to 150,000, a glass transition temperature of below 80°C, and a softening point of less than 100°C. (c) The colorant includes pigment-based colorants or dye-based colorants; (d) The color composition further comprises at least one selected from surfactants, dispersants, defoamers, organic solvents and talc; (e) The thickness of the color layer is 0.5~10μm.

4. The hot stamping film for vehicle license plates according to claim 1 or 2, characterized in that, The adhesive layer composition further comprises at least one selected from organic solvents, resins, and colorants; and the adhesive layer also satisfies one or more of the following conditions: (iii) The organic solvent comprises ethyl acetate; (iv) The resin comprises a non-crystalline polyester and / or vinyl chloride vinyl acetate copolymer, The amorphous polyester has a weight-average molecular weight of 10,000 to 100,000, a glass transition temperature of below 30°C, a hydroxyl value of 5 to 11 mgKOH / g, and an acid value of less than 2 mgKOH / g. (v) The thickness of the adhesive layer is 0.5~10μm.

5. A method for manufacturing a hot stamping film for vehicle license plates according to any one of claims 1 to 4, characterized in that, The manufacturing method includes: Process A: Apply the color composition to the substrate layer and dry to form a color layer; Step B: Apply the adhesive composition onto the color layer and dry to form an adhesive layer.

6. The manufacturing method according to claim 5, characterized in that, In process A, the drying temperature is 60~120℃ and the drying time is 0.5~5min; In step B above, the drying temperature is 60~120℃ and the drying time is 0.5~5min.

7. The manufacturing method according to claim 5 or 6, characterized in that, The color composition comprises at least one selected from resin, colorant, surfactant, dispersant, defoamer, organic solvent and talc; The adhesive composition further comprises at least one selected from organic solvents, resins, and colorants.

8. A method for manufacturing a vehicle license plate, comprising: Hot stamping is performed using the hot stamping film for vehicle license plates as described in any one of claims 1 to 4.

9. The use of the hot stamping film for vehicle license plates according to any one of claims 1 to 4 in improving the hot stamping adhesion and / or abrasion resistance in the manufacture of vehicle license plates.

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