A photopolymer material usable for hot stamping, a method of preparation and use

Abstract

This invention relates to the field of photopolymer technology, specifically to a photopolymer material, preparation method, and application for use in hot stamping. The photopolymer material comprises the following components: 30%–70% matrix resin; 2%–30% high-refractive-index monomer; 0.1%–5% photosensitizer; 2%–10% photoinitiator; and 25%–50% solvent. The matrix resin has a refractive index ≤1.50 and is a copolymer of methyl methacrylate, rigid acrylate monomers, and fluorinated or silicone-containing acrylate monomers. This application utilizes a quaternary balanced design of low refractive index, high transparency, high heat resistance, and high rigidity to achieve a heat resistance temperature higher than the hot stamping working temperature (130℃–140℃). Low elongation at break ensures clean cutting during hot pressing without stringing or sticking to the mold. Combined with the high-refractive-index monomer (2%–30%), sufficient refractive index modulation is achieved, ensuring that the holographic pattern retains high diffraction efficiency (>80%) after hot stamping. This enables the direct application of the photopolymer material in existing hot stamping equipment.

Description

Technical Field

[0001] This invention relates to the field of photopolymer technology, and in particular to a photopolymer material, preparation method and application that can be used for hot stamping. Background Technology

[0002] Photopolymers are important holographic recording materials, belonging to the photopolymerization type of photosensitive polymers. They consist of a visible light curing system and a matrix resin. When two coherent laser beams are superimposed and interfered on a holographic film, a photochemical reaction occurs at the bright fringes, forming a polymer with a refractive index different from the matrix resin. Information from the grating is recorded through refractive index modulation. The magnitude of refractive index modulation directly determines the diffraction efficiency; in practical applications, a diffraction efficiency generally greater than 80% is required.

[0003] Photopolymer materials currently have wide applications in holography, high-security protection, transparent displays, and high-density information storage. To ensure sufficient refractive index adjustment, existing products on the market generally use formulations of high-refractive-index monomers and low-refractive-index resins. However, since low-refractive-index resins typically contain fluorine and silicon, they are generally opaque and cannot be used for optical coatings. Therefore, the choice of resins in photopolymer formulations is very limited. While ensuring optical performance, it is difficult to simultaneously achieve other physicochemical properties, significantly restricting the versatility of product applications. Currently, there are almost no products that can simultaneously achieve excellent optical performance with heat resistance, slitting ability, and resistance to yellowing. However, in the high-security field, product volume is large, and high efficiency is required. Since almost all manufacturers in this field use hot stamping equipment, the development of photopolymer materials compatible with existing hot stamping equipment has become a rigid requirement.

[0004] Therefore, there is an urgent need to develop a photopolymer material that can ensure high diffraction efficiency, adapt to hot stamping processing, and has high heat resistance and good mechanical properties. Summary of the Invention

[0005] This invention provides a photopolymer material that can ensure high diffraction efficiency, adapt to hot stamping processing, and has high heat resistance and good mechanical properties, as well as its preparation method and application.

[0006] This invention discloses a photopolymer material, its preparation method, and its application for use in hot stamping. The photopolymer material comprises the following components: 30%–70% matrix resin; 2%–30% high refractive index monomer; 0.1%–5% photosensitizer; 2%–10% photoinitiator; and 25%–50% solvent; wherein the refractive index of the matrix resin is ≤1.50, and the matrix resin is a copolymer of methyl methacrylate, rigid acrylate monomer, and fluorinated or silicone-containing acrylate monomer.

[0007] Optionally, the matrix resin is composed of the following components by mass percentage: 30%–80% methyl methacrylate, 15%–50% rigid acrylate monomers, and 5%–20% fluorinated or silicone acrylate monomers.

[0008] Optionally, the rigid acrylate monomer is selected from at least one of isobornyl methacrylate, cyclohexyl methacrylate, and tert-butyl methacrylate.

[0009] Optionally, the fluorinated acrylate monomer is selected from at least one of 2,2,2-trifluoroethyl methacrylate, 2,2,3,3,3-pentafluoropropyl methacrylate, hexafluoroisopropyl methacrylate, perfluoroalkyl vinyl ether monomers, and (1H,1H-perfluorobutyl) methacrylate.

[0010] Optionally, the silicone acrylate monomer is selected from at least one of 3-(methacryloyloxy)propyltrimethoxysilane, methacryloyloxymethyltrimethylsilane, vinyltrimethylsilane, trimethylsilyl methacrylate, and bis(trimethylsiloxy)methyl methacrylate.

[0011] Optionally, the matrix resin has an elongation at break of less than 5%, a heat resistance temperature of more than 140°C, and a refractive index of less than 1.45.

[0012] This invention also discloses a method for preparing the above-mentioned photopolymer material, comprising:

[0013] Methyl methacrylate, rigid acrylate monomers, fluorinated or silicone acrylate monomers and free radical polymerization initiators are reacted in a solvent at 80°C for 2 to 8 hours in an oxygen-free environment to synthesize a matrix resin. Photopolymer materials were prepared by mixing the synthesized matrix resin with high refractive index monomers, photosensitizers, photoinitiators and solvents in a light-protected environment. Photopolymer material is coated onto a base film, dried, and then laminated with a protective film to obtain a photopolymer film.

[0014] Optionally, the preparation method further includes: laser holographic recording of a photopolymer film, followed by heating or UV post-treatment to obtain a holographic pattern product, which can be used for hot stamping.

[0015] The present invention also discloses the application of the above-mentioned photopolymer material in hot stamping, holographic anti-counterfeiting, transparent display, and AR diffraction waveguide sheet.

[0016] The beneficial effects of the photopolymer material provided in this invention are as follows: This application addresses the problem that low-refractive-index resins containing fluorine / silicon elements are opaque and difficult to use in optical coatings. This copolymer system utilizes the highly transparent main framework of methyl methacrylate (MMA), combined with a specific content of fluorine / silicon monomers to achieve a low refractive index. Simultaneously, rigid acrylate monomers are used to adjust crystallinity and compatibility, breaking the technical prejudice that fluorine / silicon resins are inherently opaque. This makes it suitable as a low-refractive-index transparent resin for optical coatings. Furthermore, addressing the difficulty in simultaneously achieving optical performance with physical and chemical properties such as heat resistance, slitting properties, and yellowing resistance, the introduction of rigid acrylate monomers imparts a highly rigid structure to the matrix resin, transforming the material from a traditional elastomer into a rigid body, while ensuring high diffraction efficiency. While requiring a low refractive index, it achieves excellent mechanical properties and thermal stability. Addressing the issue that existing materials cannot be adapted for hot stamping, this application employs a quaternary balanced design of low refractive index, high transparency, high heat resistance, and high rigidity. This design ensures the material's heat resistance temperature exceeds the hot stamping working temperature (130℃-140℃), and its low elongation at break ensures clean cutting during hot pressing without stringing or sticking to the mold. Combined with high refractive index monomers (2%–30%), sufficient refractive index modulation is achieved, guaranteeing that the holographic pattern retains high diffraction efficiency (>80%) after hot stamping. This enables the direct application of photopolymer materials on existing hot stamping equipment, meeting the rigid demands of high-safety protection, automotive HUDs, AR displays, and other fields for high-efficiency, high-heat-resistant, and high-optical-performance materials. Detailed Implementation

[0017] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The preferred embodiments of the present invention will now be described in detail.

[0018] This invention provides a photopolymer material that can be used for hot stamping. The photopolymer material comprises the following components by weight percentage: Matrix resin 30%–70%; High refractive index monomers: 2%–30%; Photosensitizer 0.1%–5%; Photoinitiator 2%–10%; Solvent 25%–50%; The matrix resin has a refractive index ≤1.50 and is a copolymer of methyl methacrylate, rigid acrylate monomers and fluorinated or silicone acrylate monomers.

[0019] This application addresses the problem that low-refractive-index resins containing fluorine / silicon elements are opaque and unsuitable for optical coatings. This copolymer system utilizes the highly transparent main framework of methyl methacrylate (MMA) and combines it with a specific amount of fluorine / silicon monomers to achieve a low refractive index. Simultaneously, rigid acrylate monomers are used to adjust crystallinity and compatibility, breaking the technical prejudice that fluorine / silicon resins are inherently opaque. This makes it a low-refractive-index transparent resin suitable for optical coatings. Furthermore, addressing the difficulty of simultaneously achieving optical performance with physicochemical properties such as heat resistance, slitting properties, and yellowing resistance, the introduction of rigid acrylate monomers imparts a highly rigid structure to the matrix resin, transforming the material from a traditional elastomer into a rigid body. This ensures the low refractive index required for high diffraction efficiency while achieving… Excellent mechanical properties and thermal stability; addressing the problem that existing materials cannot be adapted to hot stamping processing, this application adopts a quaternary balanced design of low refractive index, high transparency, high heat resistance, and high rigidity, so that the material's heat resistance temperature is higher than the hot stamping working temperature (130℃-140℃), and the low elongation at break ensures that it can be cleanly cut without stringing or sticking to the mold during hot pressing. Combined with high refractive index monomers (2%~30%), sufficient refractive index modulation is formed to ensure that the holographic pattern still has high diffraction efficiency (>80%) after hot stamping. Thus, the photopolymer material can be directly applied to existing hot stamping equipment, meeting the rigid requirements of high-safety protection, automotive HUD, AR display and other fields for high-efficiency, high-heat-resistant and high-optical-performance materials.

[0020] Specifically, resins with high fluorine-silicone content are opaque. Commercially available fluorine-silicone resins are generally used as outer coatings for optical fibers and backsheet coatings for solar panels, requiring extremely low refractive indices and as high a fluorine-silicone content as possible, without specifically considering transparency. The synthetic resin of this application can balance transparency, low refractive index, and other mechanical and thermal properties, making it suitable for applications in the field of holographic optics.

[0021] Specifically, the content of the matrix resin can be 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, or 70%.

[0022] The content of high refractive index monomers can be 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, or 30%.

[0023] The photosensitizer content can be 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3.0%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9%, 4.0%, 4.1%, 4.2%, 4.3%, 4.4%, 4.5%, 4.6%, 4.7%, 4.8%, 4.9%, or 5.0%.

[0024] The content of photoinitiator can be 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10%.

[0025] The solvent content can be 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, or 50%.

[0026] Specifically, the composition of the matrix resin, by mass percentage, is: 30%–80% methyl methacrylate, 15%–50% rigid acrylate monomers, and 5%–20% fluorinated or silicone-containing acrylate monomers. This matrix resin has a heat-resistant rigid resin with a heat treatment temperature above 140°C and an elongation at break of less than 5%, making it suitable for use as a base resin for hot stamping. Its diffraction efficiency reaches over 90%.

[0027] Specifically, the content of methyl methacrylate can be 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, 69%, 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, or 80%.

[0028] The content of rigid acrylate monomers can be 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, or 50%.

[0029] The content of fluorinated or silicone acrylate monomers can be 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, or 20%.

[0030] In the preparation of the matrix resin, the selected matrix resin and the above-mentioned synthetic monomers are first added to a reaction vessel, followed by a free radical polymerization initiator, which can be a thermally polymerizable hydrogen peroxide or azo compound. Solvents such as butyl acetate, ethyl acetate, and butanone are added to the matrix resin. Under an oxygen-free environment, at approximately 80°C, the mixture is stirred and kept at this temperature for 2-8 hours. The total monomer content is 30-60%, the total solvent content is 30-60%, and the free radical polymerization initiator content is 0.1-5%. Once a transparent, viscous liquid is formed, it is removed and set aside for use.

[0031] Peroxides include benzoyl peroxide (BPO), lauroyl peroxide (LPO), tert-Butyl hydroperoxide (TBHP), and diisopropyl peroxydicarbonate (IPP).

[0032] Azo compounds include azobisisobutyronitrile (AIBN, 2,2'-Azobis(2-methylpropionitrile)), azobisisoheptanenitrile (ABVN, 2,2'-Azobis(2,4-dimethylvaleronitrile)), and azobiscyclohexanecarbonitrile (ACN, 1,1'-Azobis(cyclohexanecarbonitrile)).

[0033] Specifically, the rigid acrylate monomer is selected from at least one of isobornyl methacrylate, cyclohexyl methacrylate, and tert-butyl methacrylate.

[0034] Specifically, the fluorinated acrylate monomer is selected from at least one of 2,2,2-trifluoroethyl methacrylate, 2,2,3,3,3-pentafluoropropyl methacrylate, hexafluoroisopropyl methacrylate, perfluoroalkyl vinyl ether monomers, and (1H,1H-perfluorobutyl) methacrylate.

[0035] Specifically, the silicone-containing acrylate monomer is selected from at least one of 3-(methacryloyloxy)propyltrimethoxysilane, methacryloyloxymethyltrimethylsilane, vinyltrimethylsilane, trimethylsilyl methacrylate, and bis(trimethylsiloxy)methyl methacrylate.

[0036] Photosensitizers can be camphorquinone (CQ), acetophenone derivatives (such as Irgacure 784, Irgacure 819), thioxanthones (TX), 2,4-bis(julonidinylmethylene)cyclopentanone, eosin Y, rhodamine B, methylene blue, rose benzoin, fluorescein and its derivatives, acridine orange, erythrosin B, pyronin Y / B, and benzimidazole derivatives (such as carbazole-benzimidazole, triphenylamine-benzimidazole, etc.).

[0037] Photoinitiators include 1-hydroxycyclohexylphenyl ketone (Irgacure 184), 2,2-dimethoxy-2-phenylacetophenone (Irgacure 651), benzoin ethers, triethanolamine, dimethylaniline, etc. Solvents for the photopolymer include butyl acetate, ethyl acetate, or butanone, etc.

[0038] Specifically, the elongation at break of the matrix resin is less than 5%, the heat resistance temperature is higher than 140°C, and the refractive index of the matrix resin is ≤1.45.

[0039] This invention also discloses a method for preparing the above-mentioned photopolymer material, comprising: Methyl methacrylate, rigid acrylate monomers, fluorinated or silicone acrylate monomers and free radical polymerization initiators are reacted in a solvent at 80°C for 2 to 8 hours in an oxygen-free environment to synthesize a matrix resin. Photopolymer materials were prepared by mixing the synthesized matrix resin with high refractive index monomers, photosensitizers, photoinitiators and solvents in a light-protected environment. Photopolymer material is coated onto a base film, dried, and then laminated with a protective film to obtain a photopolymer film.

[0040] The preparation method also includes: laser holographic recording of a photopolymer film, followed by heating or UV post-treatment to obtain a holographic pattern product, which can be used for hot stamping.

[0041] This application also discloses the application of photopolymer materials in hot stamping, holographic anti-counterfeiting, transparent display, and AR diffraction waveguide sheets.

[0042] Specifically, the above-synthesized matrix resin is mixed with a high-refractive-index monomer, a photosensitizer, a photoinitiator, and a solvent for the photopolymer in a light-protected environment to prepare the photopolymer.

[0043] The components of the above photopolymer are thoroughly mixed and stirred under safe light sources (red, green, and orange-yellow lights), then coated onto a protective film. After drying, another protective film is laminated to form a photopolymer film suitable for holographic imaging. The top and bottom protective films generally use film materials with a transmittance exceeding 90%, such as optical PET film and TAC film. In special applications, such as optical waveguide sheets, PMMA sheets, PC sheets, or glass sheets can also be used.

[0044] The coated photopolymer film is photographed and replicated by laser to produce a hologram. After post-processing with heat or UV, a product with a stable holographic pattern is obtained. The information layer of this product is sandwiched between two protective films, and the films can be peeled off from the top and bottom for hot stamping.

[0045] Then, hot stamping adhesive is applied to the holographic coating after the lower protective layer has been peeled off, or to the substrate. After the adhesive layer dries, the holographic pattern layer is bonded to the substrate, and the required geometric shape is pressed and cut out using a heated die. The upper protective film of the holographic coating is then peeled off. The stamped substrate is then rolled up to proceed to the next process.

[0046] Hot stamping is generally used in the packaging industry for paper products or plastic films. However, it can also be used to transfer patterns onto plastic sheets, glass, metal, and fabrics, such as for cards and documents requiring security protection, and round bottles. If the captured holographic pattern is a calculated grating at a specific angle, this photopolymer formulation can capture transparent optical components. Due to its designed high heat resistance, it can be used in high-temperature applications such as automotive glass.

[0047] The technical solutions of this application are further illustrated below through examples and comparative examples.

[0048] Example 1 I. Synthesis of Matrix Resin 33 parts by weight of methyl methacrylate, 16.5 parts by weight of isoborneol methacrylate, 0.5 parts by weight of azobisisobutyronitrile and 50 parts by weight of ethyl acetate were added to a reaction vessel, which was then filled with nitrogen for protection. The mixture was slowly stirred at 200 rpm at 80°C for 3 hours to obtain a matrix resin solution with a solid content of 50%.

[0049] II. Preparation of Photopolymer Solution 40g of the synthesized matrix resin solution, 0.3g of erythrosine B, 1.2g of triethanolamine, 0.6g of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, 7g of 2-(methacryloyloxy)-1,3-dithiopentane-2-thionone, 5g of o-phenylphenoxyethyl acrylate, 6g of vinylcarbazole, and 38.85g of ethyl acetate were added to a brown glass container. The mixture was stirred at 300 rpm at room temperature in the dark for 1 hour, and then allowed to stand for 4 hours to obtain the photopolymer solution. The entire process was carried out in the dark.

[0050] Among them, erythrosine B is a photosensitizer, triethanolamine and phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide are photoinitiators, and 2-(methacryloyloxy)-1,3-dithiopentane-2-thionone, o-phenylphenoxyethyl acrylate and vinylcarbazole are high refractive monomers.

[0051] III. Preparation of Photopolymer Thin Films The above photopolymer solution was uniformly coated onto a PET high-transmittance film (thickness 50μm, light transmittance >92%) using a comma-shaped doctor blade coating method (wet film thickness 50μm). After drying in a 70℃ hot air circulating oven (temperature set at 70℃, wind speed 2m / s) for 5 minutes, another layer of PET high-transmittance film was laminated, and the film was then wound up using an automatic winding machine for later use. The entire process was carried out in the dark.

[0052] IV. Photopolymer Performance Testing The refractive index of the monomer and resin solution were measured using an Abbe refractometer, and the refractive index modulation was calculated.

[0053] After passing through a 90° incident exposure reflective grating under laser light to obtain a standard test grating, it is placed in an ultraviolet-visible spectrophotometer to test the transmittance of the grating film.

[0054] Subtract the transmittance percentage from 100% to obtain the diffraction efficiency value.

[0055] Elongation at break test: After the resin is made into a standard test piece, the elongation at break is measured using a tensile testing machine.

[0056] In this embodiment, the photopolymer refractive index is modulated to approximately 0.02, the diffraction efficiency is greater than 80%, the refractive index is 1.480-1.485, the transmittance is 92%, the elongation at break is 4%, and the heat resistance temperature is greater than 130℃. Example 2 I. Synthesis of Matrix Resin 34 parts by weight of methyl methacrylate, 6 parts by weight of isoborneol methacrylate, 9.5 parts by weight of hexafluoroisopropyl methacrylate, 0.5 parts by weight of azobisisobutyronitrile, and 50 parts by weight of ethyl acetate were added to a reaction vessel and stirred slowly at 200 rpm at 80°C for 3 hours to obtain a matrix resin solution with a solid content of 50%.

[0057] II. Preparation of Photopolymer Solution 40g of the synthesized matrix resin solution, 0.3g of erythrosine B, 1.2g of triethanolamine, 0.6g of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, 7g of (4-phenyl-1,3-dithiopentane-2-yl) methacrylate, 5g of o-phenylphenoxyethyl acrylate, 6g of vinylcarbazole, and 38.85g of ethyl acetate were added to a brown glass container. The mixture was stirred at 300 rpm at room temperature in the dark for 1 hour, and then allowed to stand for 4 hours to obtain the photopolymer solution. The entire process was carried out in the dark.

[0058] III. Preparation of Photopolymer Thin Films The above photopolymer solution was uniformly coated onto a PET high-transmittance film (thickness 50μm, light transmittance >92%) using a comma-shaped doctor blade coating method (wet film thickness 50μm). After drying in a 70℃ hot air circulating oven (temperature set at 70℃, wind speed 2m / s) for 5 minutes, another layer of PET high-transmittance film was laminated, and the film was then wound up using an automatic winding machine for later use. The entire process was carried out in the dark.

[0059] IV. Photopolymer Performance Testing The refractive index of the monomer and resin solution were measured using an Abbe refractometer, and the refractive index modulation was calculated.

[0060] After passing through a 90° incident exposure reflective grating under laser light to obtain a standard test grating, it is placed in an ultraviolet-visible spectrophotometer to test the transmittance of the grating film.

[0061] Subtract the transmittance percentage from 100% to obtain the diffraction efficiency value.

[0062] Elongation at break test: After the resin is made into a standard test piece, the elongation at break is measured using a tensile testing machine.

[0063] In this embodiment, the photopolymer has a refractive index modulated to 0.021-0.022, a diffraction efficiency greater than 90%, a refractive index of 1.467, a transmittance of 90%, and an elongation at break of 5%. The heat resistance temperature is approximately 140°C.

[0064] Comparative Example 1 I. Preparation of the matrix resin Mix 50 parts by weight of commercially available polymethyl methacrylate resin with 50 parts by weight of ethyl acetate, add the mixture to a glass beaker, and stir at 300 rpm at room temperature for 2 hours using a mechanical stirrer to prepare a solution with a solid content of 50% for later use.

[0065] II. Preparation of Photopolymer Solution 40g of the prepared polymethyl methacrylate resin solution, 0.3g of erythrosine B, 1.2g of triethanolamine, 0.6g of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, 7g of 2-(methacryloyloxy)-1,3-dithiopentane-2-thionone, 5g of o-phenylphenoxyethyl acrylate, 6g of vinylcarbazole, and 38.85g of ethyl acetate were added to a brown glass container. The mixture was stirred at 300 rpm at room temperature in the dark for 1 hour, and then allowed to stand for 4 hours to obtain the photopolymer solution. The entire process was carried out in the dark.

[0066] III. Preparation of Photopolymer Thin Films The above photopolymer solution was uniformly coated onto a PET high-transparency film (thickness 50μm, light transmittance >92%) using a comma-shaped doctor blade coating method (wet film thickness 50μm). After drying in a 670℃ hot air circulating oven (temperature set at 70℃, wind speed 2m / s) for 5 minutes, another layer of PET high-transparency film was laminated on top, and the film was then wound up using an automatic winding machine for later use. The entire process was carried out in the dark.

[0067] IV. Photopolymer Performance Testing The refractive index of the monomer and resin solution were measured using an Abbe refractometer, and the refractive index modulation was calculated.

[0068] After passing through a 90° incident exposure reflective grating under laser light to obtain a standard test grating, it is placed in an ultraviolet-visible spectrophotometer to test the transmittance of the grating film.

[0069] Subtract the transmittance percentage from 100% to obtain the diffraction efficiency value.

[0070] Elongation at break test: After the resin is made into a standard test piece, the elongation at break is measured using a tensile testing machine.

[0071] In this comparative example, the photopolymer has a refractive index modulation of 0.019 and a diffraction efficiency greater than 80%. Its refractive index is 1.491, heat resistance is 110℃, indicating poor heat resistance, making it unsuitable as a primary material for hot stamping. Its elongation at break is 10%, which is slightly high.

[0072] Comparative Example 2 I. Preparation of the matrix resin Mix 50 parts by weight of ethylene-vinyl acetate copolymer resin (DuPont Elvax® 210W, VA content 9%, melt index 2.0 g / 10 min) with 50 parts by weight of ethyl acetate, add to a glass beaker, and stir at 300 rpm at room temperature for 2 hours using a mechanical stirrer to prepare a solution with a solid content of 50% for later use. II. Preparation of Photopolymer Solution 40g of the ethylene-vinyl acetate copolymer resin solution prepared above, along with 0.3g of erythrosine B, 1.2g of triethanolamine, 0.6g of phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide, 7g of 2-phenoxyethyl acrylate, 5g of o-phenylphenoxyethyl acrylate, 6g of vinylcarbazole, and 38.85g of ethyl acetate, were added to a brown glass container. The mixture was stirred at 300 rpm at room temperature in the dark for 1 hour, and then allowed to stand for 4 hours to obtain the photopolymer solution. The entire process was carried out in the dark.

[0073] III. Preparation of Photopolymer Thin Films The above photopolymer solution was uniformly coated onto a PET high-transmittance film (thickness 50μm, light transmittance >92%) using a comma-shaped doctor blade coating method (wet film thickness 50μm). After drying in a 70℃ hot air circulating oven (temperature set at 70℃, wind speed 2m / s) for 5 minutes, another layer of PET high-transmittance film was laminated, and the film was then wound up using an automatic winding machine for later use. The entire process was carried out in the dark.

[0074] IV. Photopolymer Performance Testing The refractive index of the monomer and resin solution were measured using an Abbe refractometer, and the refractive index modulation was calculated.

[0075] After passing through a 90° incident exposure reflective grating under laser light to obtain a standard test grating, it is placed in an ultraviolet-visible spectrophotometer to test the transmittance of the grating film.

[0076] Subtract the transmittance percentage from 100% to obtain the diffraction efficiency value.

[0077] Elongation at break test: After the resin is made into a standard test piece, the elongation at break is measured using a tensile testing machine.

[0078] In this comparative example, the photopolymer has a refractive index of 1.49, a refractive index modulation of 0.018, a diffraction efficiency of no more than 80%, a heat resistance temperature of 50℃, low heat resistance, and is not suitable for heat-resistant environments or hot stamping. The elongation at break is 300-500%, which is high, and the transmittance is 90%.

[0079] In Comparative Example 1 above, the elongation at break is a critical value for the hot stamping material, which is barely usable, but the refractive index modulation is not large enough, and the diffraction efficiency is far lower than that of the example. In Comparative Example 2, the elongation at break is too high, the heat resistance is poor, and it cannot be used for hot stamping and heat-resistant applications. The refractive index adjustment and diffraction efficiency are also not excellent.

[0080] It should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Those skilled in the art can modify the technical solutions described in the above embodiments, or make equivalent substitutions for some of the technical features; and all such modifications and substitutions should fall within the protection scope of the appended claims of the present invention.

Claims

1. A photopolymer material that can be used for hot stamping, characterized in that, By weight percentage, it includes the following components: Matrix resin 30%–70%; High refractive index monomers: 2%–30%; Photosensitizer 0.1%–5%; Photoinitiator 2%–10%; Solvent 25%–50%; The matrix resin has a refractive index ≤1.50 and is a copolymer of methyl methacrylate, rigid acrylate monomers and fluorinated or silicone acrylate monomers.

2. The photopolymer material according to claim 1, characterized in that, The composition of the matrix resin by mass percentage is: 30%–80% methyl methacrylate, 15%–50% rigid acrylate monomer, and 5%–20% fluorinated or silicone acrylate monomer.

3. The photopolymer material according to claim 1 or 2, characterized in that, The rigid acrylate monomer is selected from at least one of isoborneol methacrylate, cyclohexyl methacrylate, and tert-butyl methacrylate.

4. The photopolymer material according to claim 1 or 2, characterized in that, The fluorinated acrylate monomer is selected from at least one of 2,2,2-trifluoroethyl methacrylate, 2,2,3,3,3-pentafluoropropyl methacrylate, hexafluoroisopropyl methacrylate, perfluoroalkyl vinyl ether monomers, and (1H,1H-perfluorobutyl) methacrylate.

5. The photopolymer material according to claim 1 or 2, characterized in that, The silicon-containing acrylate monomer is selected from at least one of 3-(methacryloyloxy)propyltrimethoxysilane, methacryloyloxymethyltrimethylsilane, vinyltrimethylsilane, trimethylsilyl methacrylate, and bis(trimethylsiloxy)methyl methacrylate.

6. The photopolymer material according to claim 1, characterized in that, The matrix resin has an elongation at break of less than 5%, a heat resistance temperature of more than 140°C, and a refractive index of less than 1.

45.

7. A method for preparing the photopolymer material according to any one of claims 1 to 6, comprising: Methyl methacrylate, rigid acrylate monomers, fluorinated or silicone acrylate monomers and free radical polymerization initiators are reacted in a solvent at 80°C for 2 to 8 hours in an oxygen-free environment to synthesize a matrix resin. Photopolymer materials were prepared by mixing the synthesized matrix resin with high refractive index monomers, photosensitizers, photoinitiators and solvents in a light-protected environment. Photopolymer material is coated onto a base film, dried, and then laminated with a protective film to obtain a photopolymer film.

8. The preparation method according to claim 7, characterized in that, Also includes: A holographic pattern product is obtained by laser holographic recording of a photopolymer film and then post-processing it with heat or UV. The holographic pattern product can be used for hot stamping.

9. The application of the photopolymer material according to any one of claims 1 to 6 in hot stamping, holographic anti-counterfeiting, transparent display, and AR diffraction waveguide sheet.