A transparent / colored alternating laminated structure-based adjustable light transmittance privacy film and a lamination preparation method thereof

Abstract

The application discloses a kind of based on transparent / coloring alternately laminated structure adjustable light transmittance privacy film and its laminated preparation method, it is related to privacy film technical field, by transparent film layer and coloring glue layer of alternately laminated composition, the coloring glue layer includes as follows each raw material is made: acrylate end-capped hyperbranched organic silicon modified polyurethane, UV color paste, graphene oxide quantum dot, vinyl trimethoxysilane, 1,3-bis (oxymethylene methyl) -5- (2-propenyl) -1,3,5-triazine-2,4,6 (1H,3H,5H) -trione, 1,4-diacryl-1,2,3,4-tetrahydro-6,7-dimethylquinoxaline, allyl succinimidyl carbonate, 2-vinyl pyrimidine, 2,6-diaminopurine, bicyclo [2.2.1] heptane dimethylamine, photoinitiator, diluent.The privacy film light transmittance is adjustable, and the privacy effect is remarkable, and interlayer binding force is strong, and the performance of enough moisture and heat aging resistance.

Description

Technical Field

[0001] This invention relates to the field of privacy film technology, and in particular to a privacy film with adjustable light transmittance based on an alternating transparent / colored lamination structure and its lamination preparation method. Background Technology

[0002] In today's information age, the application of electronic display devices is becoming increasingly widespread, and the risk of information leakage is also gradually increasing. Privacy films, as products that reduce the viewing angle of electronic devices and decrease the viewing effect at oblique angles, thereby effectively protecting screen information security, have gained widespread use.

[0003] Most privacy screen protectors on the market currently use a louvered structure or microstructure grating technology. While these protectors can achieve a certain level of privacy, their structural limitations result in low light transmittance, severely impacting screen display quality. Users may experience insufficient screen brightness and color distortion, significantly reducing the user experience. Some privacy screen protectors have a fixed privacy angle, making them unadjustable for different usage scenarios. In certain environments, such as strong outdoor light or viewing angles, fixed-angle protectors struggle to meet diverse usage requirements, presenting significant limitations. Furthermore, they are typically produced using a precision mold imprinting process (microstructure transfer). Due to limitations in the material and manufacturing process of the structural rollers, the width of the shielding layer cannot be reduced. This limits the reduction in the ratio of the shielding layer width to the transparent area width, resulting in significant light transmittance loss and affecting normal use.

[0004] In terms of manufacturing processes, traditional privacy films are relatively complex and costly to produce. Some processes require the use of special materials and equipment, increasing the difficulty and cost of production and limiting the large-scale production and application of privacy films. Moreover, privacy films manufactured using traditional processes also have certain problems in terms of structural stability and durability. After prolonged use, they are prone to delamination, deformation, and other issues, affecting their privacy protection effect and lifespan.

[0005] For example, Chinese invention patent application number 201711453776.9 discloses a privacy film, which sequentially includes an upper support layer, a privacy layer, and a lower support layer. The privacy layer includes diffusion units and light-transmitting units, with the light-transmitting units filling the spaces between the diffusion units. The diffusion units include light-diffusing particles. By adding light-diffusing particles to the micro-visor structure, the problem of low light transmittance in existing privacy films is solved. However, this manufacturing method is complex, requiring two fillings of diffusion units and light-transmitting units. Furthermore, the small spacing between the micro-visor structures makes incomplete filling and the presence of air bubbles a common defect.

[0006] It is evident that developing an adjustable transmittance privacy film based on an alternating transparent / colored lamination structure, with adjustable transmittance, significant privacy effect, strong interlayer bonding, and sufficient resistance to damp heat aging, and its lamination preparation method, meets market demand, has broad market value and application prospects, and is of great significance to promoting the development of privacy film production and preparation technology. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the prior art and provide an adjustable transmittance privacy film based on a transparent / colored alternating lamination structure and its lamination preparation method, which has adjustable transmittance, significant privacy effect, strong interlayer bonding, and good resistance to damp heat aging.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is: an adjustable transmittance privacy film based on an alternating transparent / colored lamination structure, comprising alternatingly laminated transparent film layers and colored adhesive layers, wherein the colored adhesive layer comprises the following raw materials in parts by weight: 25-35 parts of acrylate-terminated hyperbranched silicone-modified polyurethane, 5-10 parts of UV color paste, 1-3 parts of graphene oxide quantum dots, 0.5-1.5 parts of vinyltrimethoxysilane, and 1,3-bis(ethylene oxide) 3-5 parts of methyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 2-4 parts of 1,4-disacryloyl-1,2,3,4-tetrahydro-6,7-dimethylquinoxaline, 3-5 parts of allyl succinimide carbonate, 1-3 parts of 2-vinylpyrimidine, 1-3 parts of 2,6-diaminopurine, 1-3 parts of bicyclo[2.2.1]heptanedimethylamine, 0.3-0.5 parts of photoinitiator, and 30 parts of diluent.

[0009] Preferably, there are no special requirements regarding the source of the acrylate-terminated hyperbranched silicone-modified polyurethane. In one embodiment of the present invention, the acrylate-terminated hyperbranched silicone-modified polyurethane is prepared according to the method of Example 1 in the authorized publication number CN111393608B.

[0010] Preferably, the UV colorant is Clariant Hostatint UV Colorant Black N30.

[0011] Preferably, the graphene oxide quantum dots have a thickness of 1-2 nm, a number of layers of 1-5, a lateral dimension of 5-15 nm, are numbered XF074, have a CAS number of 7440-44-0, and are provided by Jiangsu Xianfeng Nanomaterials Technology Co., Ltd.

[0012] Preferably, the photoinitiator is benzoin ether.

[0013] Preferably, the diluent is a mixture of 2-methoxyethyl acrylate and methyl methacrylate in a mass ratio of 1:(3-5).

[0014] Preferably, the light transmittance of the transparent film layer is ≥90%.

[0015] Preferably, the transparent film material is selected from any one of PET, PC, PMMA, and COP.

[0016] Preferably, the thickness of the transparent film layer is 5-100 μm; the thickness of the colored adhesive layer is 1-100 μm.

[0017] Preferably, the total number of layers of the privacy film is 8-50.

[0018] Another object of the present invention is to provide a method for laminating and preparing the privacy film with adjustable transmittance based on the alternating transparent / colored lamination structure, comprising the following steps:

[0019] Step S1: Cut the transparent film material into appropriate sizes, and perform cleaning and surface activation treatment in sequence to obtain the pretreated transparent film.

[0020] Step S2: Mix all the raw materials of the coloring adhesive layer evenly and then degas under vacuum to obtain a coating liquid; coat the coating liquid evenly on the upper surface of the transparent film layer, and then cover the adhesive layer with another transparent film layer. After curing with ultraviolet light and pressing with hot rollers, repeat the above steps to stack them into the required thickness.

[0021] Step S3: Cut to obtain the privacy film of the target size.

[0022] Preferably, the surface activity treatment in step S1 takes 10-60 seconds; the surface activity treatment is a corona treatment or a primer treatment.

[0023] Preferably, the conditions for UV curing in step S2 are: the wavelength of the UV light is 220-300nm and the irradiation time is 3-5min.

[0024] Preferably, the temperature of the hot roller pressing in step S2 is 78-95℃, the pressure is 0.5-2MPa, and the time is 10-30s; the coating in step S2 adopts any one of the following processes: gravure coating, slot coating, and spin coating.

[0025] Preferably, the cutting in step S3 is either laser cutting or diamond wire cutting.

[0026] The adjustable transmittance privacy film based on the transparent / colored alternating lamination structure of the present invention has the following adjustment mechanism: the transmittance is dynamically adjusted by adjusting the thickness ratio and number of layers of the transparent film layer and the colored adhesive layer.

[0027] Due to the application of the above technical solution, the present invention has the following beneficial effects:

[0028] (1) The laminated preparation method of the privacy film with adjustable transmittance based on the alternating transparent / colored lamination structure disclosed in this invention is simple in process, convenient in operation and control, has high preparation efficiency and finished product qualification rate, low dependence on equipment, suitable for continuous large-scale production, and has high promotion and application value.

[0029] (2) The adjustable transmittance privacy film based on an alternating transparent / colored lamination structure disclosed in this invention is composed of alternatingly laminated transparent film layers and colored adhesive layers. The colored adhesive layer comprises the following raw materials in parts by weight: 25-35 parts of acrylate-terminated hyperbranched silicone-modified polyurethane, 5-10 parts of UV colorant, 1-3 parts of graphene oxide quantum dots, 0.5-1.5 parts of vinyltrimethoxysilane, and 1,3-bis(epoxyethylenemethyl)-5-( 3-5 parts of 2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 2-4 parts of 1,4-disacryloyl-1,2,3,4-tetrahydro-6,7-dimethylquinoxaline, 3-5 parts of allyl succinimide carbonate, 1-3 parts of 2-vinylpyrimidine, 1-3 parts of 2,6-diaminopurine, 1-3 parts of bicyclo[2.2.1]heptanedimethylamine, 0.3-0.5 parts of photoinitiator, and 30 parts of diluent. By replacing the traditional grating structure with alternating lamination, dynamic adjustment of light transmittance is achieved. Simply adjusting the thickness ratio and number of layers of the transparent film and the colored adhesive layer allows for flexible adjustment of the privacy film's light transmittance, meeting the needs of different users in various scenarios. Through the rational selection of the transparent film material and the formulation of the colored adhesive layer, the combined effect of these raw materials results in an adjustable light transmittance, significant privacy protection, strong interlayer bonding, and excellent resistance to damp heat aging. Simultaneously, the introduction of hyperbranched organosilicon-modified polyurethane, trimethoxysilane, triazine, quinoxaline, succinimide carbonate, pyrimidine, purine, and bicyclic [2.2.1]heptane structures, under the multiple effects of electronic effects, steric hindrance effects, and conjugation effects, makes the resulting privacy film exhibit stronger interlayer bonding and better resistance to damp heat aging. Furthermore, these raw materials exhibit good compatibility with UV color pastes and graphene oxide quantum dots. Their combined effect effectively improves the light absorption of the color paste layer. The addition of graphene oxide quantum dots not only improves compatibility and dispersion uniformity but also achieves selective light absorption at specific wavelengths through the quantum confinement effect, significantly enhancing the light absorption performance compared to traditional black fillers such as carbon black. The combined use of UV color pastes and graphene oxide quantum dots improves aging resistance and prevents performance degradation during use.

[0030] (3) The adjustable transmittance privacy film based on the transparent / colored alternating lamination structure disclosed in this invention achieves a microstructure with black and transparent intervals by coating, bonding and cutting. It does not use structural wheel transfer printing, but uses micro-concave coating process, which can make the width of the black area narrower and reduce the ratio of the width of the black area to the width of the transparent area, thereby achieving effective adjustment of transmittance with a wide adjustment range. The production process is completely subverted, eliminating the structural wheel, reducing the constraints of production equipment and reducing production costs.

[0031] (4) The adjustable transmittance privacy film based on a transparent / colored alternating lamination structure disclosed in this invention effectively overcomes the technical problems of traditional privacy films, such as long production cycles and high costs due to the need for precision mold imprinting, multiple coatings and solvent evaporation processes, and optical distortion caused by interlayer stress, through the reasonable selection of process parameters and preparation steps. It also avoids the technical defects of existing privacy films, which mainly rely on the optical properties of the material itself or the adjustment of structural thickness for transmittance adjustment, but are limited by the refractive index matching of the material and have a limited adjustment range; and multi-layer composite structures are prone to moiré interference, affecting display clarity. The transparent film layer provides the light path, and the colored adhesive layer controls the light absorption rate by adding UV pigments and graphene oxide quantum dots and adjusting the thickness. The multi-layer superposition produces a cumulative light-blocking effect, while destroying the continuous transmission path of large-angle incident light. Laser cutting or diamond wire cutting ensures dimensional accuracy; the alternating lamination structure ensures a stable privacy effect from all angles, providing uniform and precise line-of-sight blocking and effectively protecting user privacy; the size and light transmittance of the privacy film can be flexibly adjusted according to the screen size and display characteristics of different electronic devices, making it highly versatile and suitable for a variety of devices. Detailed Implementation

[0032] The following description is intended to disclose the invention and enable those skilled in the art to implement it. The preferred embodiments described below are merely examples, and other obvious variations will occur to those skilled in the art.

[0033] Example 1

[0034] An adjustable transmittance privacy film based on an alternating transparent / colored lamination structure is composed of alternating laminated transparent film layers and colored adhesive layers. The colored adhesive layer is made of the following raw materials in parts by weight: 25 parts of acrylate-terminated hyperbranched silicone-modified polyurethane, 5 parts of UV color paste, 1 part of graphene oxide quantum dots, 0.5 parts of vinyltrimethoxysilane, 3 parts of 1,3-bis(epoxyethylenemethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 2 parts of 1,4-disacryloyl-1,2,3,4-tetrahydro-6,7-dimethylquinoxaline, 3 parts of allyl succinimide carbonate, 1 part of 2-vinylpyrimidine, 1 part of 2,6-diaminopurine, 1 part of bicyclo[2.2.1]heptanedimethylamine, 0.3 parts of photoinitiator, and 30 parts of diluent.

[0035] The acrylate-terminated hyperbranched silicone-modified polyurethane was prepared according to the method in Example 1 of CN111393608B; the UV colorant was Clariant Hostatint UV Colorant Black N30; the graphene oxide quantum dots had a thickness of 1-2 nm, a number of 1-5 layers, a lateral dimension of 5-15 nm, were numbered XF074, and had a CAS number of 7440-44-0, and were provided by Jiangsu Xianfeng Nanomaterials Technology Co., Ltd.; the photoinitiator was benzoin ether; and the diluent was a mixture of 2-methoxyethyl ester and methyl methacrylate in a mass ratio of 1:3.

[0036] The transparent film material is polyethylene terephthalate (PET); the thickness of a single layer of the transparent film is 50 μm; the thickness of a single layer of the colored adhesive layer is 1 μm; and the total number of layers of the privacy film is 10.

[0037] A method for laminating a privacy film with adjustable transmittance based on an alternating transparent / colored lamination structure includes the following steps:

[0038] Step S1: Cut the transparent film material into appropriate sizes, and perform cleaning and corona treatment in sequence to obtain the pre-treated transparent film.

[0039] Step S2: After mixing all the raw materials of the coloring adhesive layer evenly, vacuum degassing is performed to obtain the coating liquid; the coating liquid is evenly coated on the upper surface of the transparent film layer using a micro-gravure coating process, and then another transparent film layer is placed on the adhesive layer. After curing with ultraviolet light and hot roller pressing, the above steps are repeated to stack them into the required thickness.

[0040] Step S3: Cut to obtain the privacy film of the target size.

[0041] The corona treatment time in step S1 is 10s; the ultraviolet curing conditions in step S2 are: the wavelength of ultraviolet light is 220nm and the irradiation time is 3min; the temperature of the hot roller pressing in step S2 is 78℃, the pressure is 0.5MPa, and the time is 10s; the cutting in step S3 is laser cutting.

[0042] Example 2

[0043] An adjustable transmittance privacy film based on an alternating transparent / colored lamination structure is composed of alternating transparent film layers and colored adhesive layers. The colored adhesive layer is made from the following raw materials in parts by weight: 28 parts acrylate-terminated hyperbranched silicone-modified polyurethane, 6 parts UV colorant, 1.5 parts graphene oxide quantum dots, 0.8 parts vinyltrimethoxysilane, and 1,3-bis(epoxyethylenemethyl)-5-(2-propenyl)- 3.5 parts of 1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 2.5 parts of 1,4-disacryloyl-1,2,3,4-tetrahydro-6,7-dimethylquinoxaline, 3.5 parts of allyl succinimide carbonate, 1.5 parts of 2-vinylpyrimidine, 1.5 parts of 2,6-diaminopurine, 1.5 parts of bicyclo[2.2.1]heptanedimethylamine, 0.35 parts of photoinitiator, and 30 parts of diluent.

[0044] The acrylate-terminated hyperbranched silicone-modified polyurethane was prepared according to the method in Example 1 of the authorized announcement number CN111393608B; the UV colorant was Clariant Hostatint UV Colorant Black N30; the graphene oxide quantum dots had a thickness of 1-2 nm, a number of 1-5 layers, a lateral dimension of 5-15 nm, and were numbered XF074 and CAS number 7440-44-0, and were provided by Jiangsu Xianfeng Nanomaterials Technology Co., Ltd.; the photoinitiator was benzoin ether; and the diluent was a mixture of 2-methoxyethyl ester and methyl methacrylate in a mass ratio of 1:3.5.

[0045] The transparent film layer material is polycarbonate (PC); the single-layer thickness of the transparent film layer is 50 μm; the single-layer thickness of the colored adhesive layer is 10 μm; the total number of layers of the privacy film is 10.

[0046] A method for laminating a privacy film with adjustable transmittance based on an alternating transparent / colored lamination structure includes the following steps:

[0047] Step S1: Cut the transparent film material into appropriate sizes, and perform cleaning and primer treatment in sequence to obtain the pre-treated transparent film.

[0048] Step S2: After mixing all the raw materials of the coloring adhesive layer evenly, vacuum degassing is performed to obtain the coating liquid; the coating liquid is evenly coated on the upper surface of the transparent film layer using a slit coating process, and then another transparent film layer is placed on the adhesive layer. After curing with ultraviolet light and hot roller pressing, the above steps are repeated to stack them into the required thickness.

[0049] Step S3: Cut to obtain the privacy film of the target size.

[0050] The primer treatment time in step S1 is 20s; the UV curing conditions in step S2 are: UV wavelength of 240nm and irradiation time of 3.5min; the hot roller pressing temperature in step S2 is 83℃, pressure of 1.1MPa, and time of 15s; the cutting in step S3 is diamond wire cutting.

[0051] Example 3

[0052] An adjustable transmittance privacy film based on an alternating transparent / colored lamination structure is composed of alternating laminated transparent film layers and colored adhesive layers. The colored adhesive layer is made of the following raw materials in parts by weight: 30 parts of acrylate-terminated hyperbranched silicone-modified polyurethane, 8 parts of UV color paste, 2 parts of graphene oxide quantum dots, 1 part of vinyltrimethoxysilane, 4 parts of 1,3-bis(epoxyethylenemethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 3 parts of 1,4-diacetyl-1,2,3,4-tetrahydro-6,7-dimethylquinoxaline, 4 parts of allyl succinimide carbonate, 2 parts of 2-vinylpyrimidine, 2 parts of 2,6-diaminopurine, 2 parts of bicyclo[2.2.1]heptanedimethylamine, 0.4 parts of photoinitiator, and 30 parts of diluent.

[0053] The acrylate-terminated hyperbranched silicone-modified polyurethane was prepared according to the method in Example 1 of the authorized announcement number CN111393608B; the UV colorant was Clariant Hostatint UV Colorant Black N30; the graphene oxide quantum dots had a thickness of 1-2 nm, a number of 1-5 layers, a lateral dimension of 5-15 nm, and were numbered XF074 and CAS number 7440-44-0, and were provided by Jiangsu Xianfeng Nanomaterials Technology Co., Ltd.; the photoinitiator was benzoin ether; and the diluent was a mixture of 2-methoxyethyl ester and methyl methacrylate in a mass ratio of 1:4.

[0054] The transparent film material is polymethyl methacrylate (PMMA); the thickness of a single layer of the transparent film is 50 μm; the thickness of a single layer of the colored adhesive layer is 20 μm; and the total number of layers of the privacy film is 10.

[0055] A method for laminating a privacy film with adjustable transmittance based on an alternating transparent / colored lamination structure includes the following steps:

[0056] Step S1: Cut the transparent film material into appropriate sizes, and perform cleaning and corona treatment in sequence to obtain the pre-treated transparent film.

[0057] Step S2: After mixing all the raw materials of the coloring adhesive layer evenly, vacuum degassing is performed to obtain the coating liquid; the coating liquid is evenly coated on the upper surface of the transparent film layer using a spin coating process, and then another transparent film layer is placed on the adhesive layer. After UV curing and hot roller pressing, the above steps are repeated to stack them into the required thickness.

[0058] Step S3: Cut to obtain the privacy film of the target size.

[0059] The corona treatment time in step S1 is 30s; the ultraviolet curing conditions in step S2 are: the wavelength of ultraviolet light is 260nm and the irradiation time is 4min; the temperature of the hot roller pressing in step S2 is 85℃, the pressure is 1.5MPa, and the time is 20s; the cutting in step S3 is laser cutting.

[0060] Example 4

[0061] An adjustable transmittance privacy film based on an alternating transparent / colored lamination structure is composed of alternating transparent film layers and colored adhesive layers. The colored adhesive layer is made from the following raw materials in parts by weight: 33 parts acrylate-terminated hyperbranched silicone-modified polyurethane, 9 parts UV colorant, 2.5 parts graphene oxide quantum dots, 1.3 parts vinyltrimethoxysilane, and 1,3-bis(epoxyethylenemethyl)-5-(2-propenyl)- 4.5 parts of 1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 3.5 parts of 1,4-disacryloyl-1,2,3,4-tetrahydro-6,7-dimethylquinoxaline, 4.5 parts of allyl succinimide carbonate, 2.5 parts of 2-vinylpyrimidine, 2.5 parts of 2,6-diaminopurine, 2.5 parts of bicyclo[2.2.1]heptanedimethylamine, 0.45 parts of photoinitiator, and 30 parts of diluent.

[0062] The acrylate-terminated hyperbranched silicone-modified polyurethane was prepared according to the method in Example 1 of the authorized announcement number CN111393608B; the UV colorant was Clariant Hostatint UV Colorant Black N30; the graphene oxide quantum dots had a thickness of 1-2 nm, a number of 1-5 layers, a lateral dimension of 5-15 nm, and were numbered XF074 and CAS number 7440-44-0, and were provided by Jiangsu Xianfeng Nanomaterials Technology Co., Ltd.; the photoinitiator was benzoin ether; and the diluent was a mixture of 2-methoxyethyl ester and methyl methacrylate in a mass ratio of 1:4.5.

[0063] The transparent film material is a cyclic olefin polymer COP (Zeon 1020R); the thickness of a single layer of the transparent film is 50 μm; the thickness of a single layer of the colored adhesive layer is 30 μm; and the total number of layers of the privacy film is 10.

[0064] A method for laminating a privacy film with adjustable transmittance based on an alternating transparent / colored lamination structure includes the following steps:

[0065] Step S1: Cut the transparent film material into appropriate sizes, and perform cleaning and corona treatment in sequence to obtain the pre-treated transparent film.

[0066] Step S2: After mixing all the raw materials of the coloring adhesive layer evenly, vacuum degassing is performed to obtain the coating liquid; the coating liquid is evenly coated on the upper surface of the transparent film layer using a micro-gravure coating process, and then another transparent film layer is placed on the adhesive layer. After curing with ultraviolet light and hot roller pressing, the above steps are repeated to stack them into the required thickness.

[0067] Step S3: Cut to obtain the privacy film of the target size.

[0068] The corona treatment time in step S1 is 50s; the ultraviolet curing conditions in step S2 are: the wavelength of ultraviolet light is 290nm and the irradiation time is 4.5min; the temperature of the hot roller pressing in step S2 is 93℃, the pressure is 1.8MPa and the time is 25s; the cutting in step S3 is laser cutting.

[0069] Example 5

[0070] An adjustable transmittance privacy film based on an alternating transparent / colored lamination structure is composed of alternating laminated transparent film layers and colored adhesive layers. The colored adhesive layer is made of the following raw materials in parts by weight: 35 parts of acrylate-terminated hyperbranched silicone-modified polyurethane, 10 parts of UV color paste, 3 parts of graphene oxide quantum dots, 1.5 parts of vinyltrimethoxysilane, 5 parts of 1,3-bis(epoxyethylenemethyl)-5-(2-propenyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 4 parts of 1,4-disacryloyl-1,2,3,4-tetrahydro-6,7-dimethylquinoxaline, 5 parts of allyl succinimide carbonate, 3 parts of 2-vinylpyrimidine, 3 parts of 2,6-diaminopurine, 3 parts of bicyclo[2.2.1]heptanedimethylamine, 0.5 parts of photoinitiator, and 30 parts of diluent.

[0071] The acrylate-terminated hyperbranched silicone-modified polyurethane was prepared according to the method in Example 1 of CN111393608B; the UV colorant was Clariant Hostatint UV Colorant Black N30; the graphene oxide quantum dots had a thickness of 1-2 nm, a number of 1-5 layers, a lateral dimension of 5-15 nm, and were numbered XF074 and CAS number 7440-44-0, and were provided by Jiangsu Xianfeng Nanomaterials Technology Co., Ltd.; the photoinitiator was benzoin ether; and the diluent was a mixture of 2-methoxyethyl ester and methyl methacrylate in a mass ratio of 1:5.

[0072] The transparent film material is polyethylene terephthalate (PET); the thickness of a single layer of the transparent film is 50 μm; the thickness of a single layer of the colored adhesive layer is 40 μm; and the total number of layers of the privacy film is 10.

[0073] A method for laminating a privacy film with adjustable transmittance based on an alternating transparent / colored lamination structure includes the following steps:

[0074] Step S1: Cut the transparent film material into appropriate sizes, and perform cleaning and corona treatment in sequence to obtain the pre-treated transparent film.

[0075] Step S2: After mixing all the raw materials of the coloring adhesive layer evenly, vacuum degassing is performed to obtain the coating liquid; the coating liquid is evenly coated on the upper surface of the transparent film layer using a micro-gravure coating process, and then another transparent film layer is placed on the adhesive layer. After curing with ultraviolet light and hot roller pressing, the above steps are repeated to stack them into the required thickness.

[0076] Step S3: Cut to obtain the privacy film of the target size.

[0077] The corona treatment time in step S1 is 60s; the ultraviolet curing conditions in step S2 are: the wavelength of ultraviolet light is 300nm and the irradiation time is 5min; the temperature of the hot roller pressing in step S2 is 95℃, the pressure is 2MPa, and the time is 30s; the cutting in step S3 is laser cutting.

[0078] Comparative Example 1

[0079] An adjustable transmittance privacy film based on a transparent / colored alternating laminated structure and its lamination preparation method are basically the same as those in Example 1, except that an equal amount of UV color paste is used instead of graphene oxide quantum dots, and 1,4-disacryloyl-1,2,3,4-tetrahydro-6,7-dimethylquinoxaline is not added.

[0080] Comparative Example 2

[0081] An adjustable transmittance privacy film based on a transparent / colored alternating lamination structure and its lamination preparation method are basically the same as those in Example 1, except that allyl succinimide carbonate and 2,6-diaminopurine are not added.

[0082] To further illustrate the beneficial technical effects of the adjustable transmittance privacy film based on the alternating transparent / colored lamination structure involved in the various embodiments of the present invention, relevant performance tests were conducted on the adjustable transmittance privacy films based on the alternating transparent / colored lamination structure involved in Examples 1-5 and Comparative Examples 1-2. The test results are shown in Table 1.

[0083] (1) Transmittance test: The transmittance was tested in accordance with the national standard GB / T 2410-2022 "Determination of transmittance and haze of transparent plastics" with a test wavelength range of 380-780nm.

[0084] (2) Privacy Angle Test: The screen of the electronic device with the privacy film installed was placed vertically, and an observation point was set at a certain distance in front of the screen. By changing the observation angle, the visibility of the screen content was observed, and the maximum observation angle at which the screen content could be clearly seen was recorded to evaluate the privacy effect of the privacy film. During the test, the ambient brightness was 700 LUX, the distance between the screen and the observation point was 35 cm, and the observation time was 4 seconds.

[0085] (3) Adhesion test: The cross-cut test method was adopted. Referring to GB / T 9286-1998 "Cross-cut test of paint and varnish film", a 1mm×1mm square array was drawn on the surface of the privacy film using a cross-cutting tool. Then, 3M tape was pasted on the cross-cut area, and the tape was quickly peeled off. The peeling off of the color glue layer in the square area was observed to evaluate the adhesion between the layers.

[0086] (4) Test of resistance to damp heat aging: Each privacy film was placed in an environment of 85°C and 85% relative humidity for 150 hours. After cooling to room temperature, the privacy angle was tested again according to the method in (1), and the rate of change of the privacy angle was calculated. The larger the value, the worse the resistance to damp heat aging.

[0087] Table 1. Performance test results of privacy films with adjustable light transmittance based on transparent / colored alternating lamination structure.

[0088]

[0089] As can be seen from Table 1, the adjustable transmittance privacy film based on the transparent / colored alternating lamination structure involved in the embodiments of the present invention has a large adjustable range of transmittance and privacy angle. From the data comparison of Example 1, Comparative Example 1 and Comparative Example 2, it can be seen that the adjustable transmittance privacy film based on the transparent / colored alternating lamination structure involved in the embodiments of the present invention has better privacy effect, resistance to damp heat aging and interlayer bonding than the comparative example product. The combined use of graphene oxide quantum dots, 1,4-disacryloyl-1,2,3,4-tetrahydro-6,7-dimethylquinoxaline, allyl succinimide carbonate and 2,6-diaminopurine is beneficial to improving the above performance.

[0090] The above embodiments are only for illustrating the technical concept and features of the present invention. Their purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be used to limit the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A privacy film with adjustable light transmittance based on an alternating transparent / colored lamination structure, characterized in that, It is composed of alternating laminated transparent film layers and colored adhesive layers. The colored adhesive layer comprises the following raw materials in parts by weight: 25-35 parts of acrylate-terminated hyperbranched silicone-modified polyurethane, 5-10 parts of UV colorant, 1-3 parts of graphene oxide quantum dots, 0.5-1.5 parts of vinyltrimethoxysilane, and 1,3-bis(epoxyethylenemethyl)-5-(2-propenyl)-1,3,5-triazine. 3-5 parts of 2,4,6(1H,3H,5H)-trione, 2-4 parts of 1,4-disacryloyl-1,2,3,4-tetrahydro-6,7-dimethylquinoxaline, 3-5 parts of allyl succinimide carbonate, 1-3 parts of 2-vinylpyrimidine, 1-3 parts of 2,6-diaminopurine, 1-3 parts of bicyclo[2.2.1]heptanedimethylamine, 0.3-0.5 parts of photoinitiator, and 30 parts of diluent.

2. The adjustable transmittance privacy film based on an alternating transparent / colored lamination structure according to claim 1, characterized in that, The UV colorant is Clariant Hostatint UV Colorant Black N30.

3. The adjustable transmittance privacy film based on an alternating transparent / colored lamination structure according to claim 1, characterized in that, The graphene oxide quantum dots have a thickness of 1-2 nm, a number of layers of 1-5, and a lateral dimension of 5-15 nm.

4. The adjustable transmittance privacy film based on an alternating transparent / colored lamination structure according to claim 1, characterized in that, The photoinitiator is benzoin ether; the diluent is a mixture of 2-methoxyethyl 2-acrylate and methyl methacrylate in a mass ratio of 1:(3-5).

5. The adjustable transmittance privacy film based on an alternating transparent / colored lamination structure according to claim 1, characterized in that, The light transmittance of the transparent film layer is ≥90%; the transparent film layer material is selected from any one of PET, PC, PMMA, and COP.

6. The adjustable transmittance privacy film based on an alternating transparent / colored lamination structure according to claim 1, characterized in that, The thickness of a single layer of the transparent film is 5-100 μm; the thickness of a single layer of the colored adhesive layer is 1-100 μm; and the total number of layers of the privacy film is 8-50.

7. A method for preparing a privacy film with adjustable transmittance based on an alternating transparent / colored lamination structure according to any one of claims 1-6, characterized in that, Includes the following steps: Step S1: Cut the transparent film material into appropriate sizes, and perform cleaning and surface activation treatment in sequence to obtain the pretreated transparent film. Step S2: Mix all the raw materials of the coloring adhesive layer evenly and then degas under vacuum to obtain a coating liquid; coat the coating liquid evenly on the upper surface of the transparent film layer, and then cover the adhesive layer with another transparent film layer. After curing with ultraviolet light and pressing with hot rollers, repeat the above steps to stack them into the required thickness. Step S3: Cut to obtain the privacy film of the target size.

8. The method for preparing an adjustable transmittance privacy film based on an alternating transparent / colored lamination structure according to claim 7, characterized in that, The surface activity treatment in step S1 takes 10-60 seconds; the surface activity treatment is either corona treatment or primer treatment.

9. The method for preparing an adjustable transmittance privacy film based on an alternating transparent / colored lamination structure according to claim 7, characterized in that, The conditions for UV curing in step S2 are as follows: the wavelength of the UV light is 220-300nm, and the irradiation time is 3-5min; the temperature of the hot roller pressing in step S2 is 78-95℃, the pressure is 0.5-2MPa, and the time is 10-30s; the coating in step S2 is any one of the following processes: gravure coating, slot coating, and spin coating.

10. The method for preparing an adjustable transmittance privacy film based on an alternating transparent / colored lamination structure according to claim 7, characterized in that, The cutting described in step S3 can be either laser cutting or diamond wire cutting.

Images