Adhesive Color Lightguiding Film with Fine Moth-eye Pattern and its Manufacturing Method

Abstract

The present invention relates to an adhesive color light guide film having a moth-eye micro-pattern, characterized by comprising: a substrate film layer doped with a phosphor or quantum dot for color light conversion; a moth-eye pattern layer having a moth-eye micro-pattern formed on the upper surface of the substrate film layer; and an adhesive layer positioned on top of the moth-eye pattern layer to be adhered. According to the present invention, light efficiency can be maximized by lowering the light reflectance to 0.5% or less and improving the transmittance to 95% or more through the moth-eye micro-pattern.

Description

Technology Field

[0001] The present invention relates to an adhesive color light guide film, and more specifically, to an adhesive color light guide film having a moth-eye micro pattern that has improved light extraction efficiency and viewing angle characteristics by including a moth-eye micro nanopattern structure and having color light emission and adhesive functions. Background Technology

[0002] Generally, light guide plates or light guide films are used in display devices, lighting devices, signage devices, etc., to effectively diffuse and control light sources. Light guide plates primarily consist of flat polymer substrates (e.g., PMMA, PC, PP, PE, etc.) with a specific pattern formed on them to uniformly diffuse light incident from a light source forward or in a selected direction.

[0003] In conventional light guide plate manufacturing technology, various process technologies such as CNC machining, laser engraving, silkscreen printing, and injection molding have been applied. Among these, the method of processing or printing dot patterns on PMMA or PC plates is used as a representative method. However, this structure contains several problems as follows.

[0004] First, the processing time required to form the light guide pattern is very long, and the work process to ensure precision is complex. For example, CNC or laser processing requires forming patterns at individual locations, which results in low productivity and is inefficient for manufacturing large-area films.

[0005] Second, the process requires a large facility space and entails high equipment investment costs. In particular, since cleanroom facilities and the establishment of a process environment for high-precision machining or precision printing are essential, its utilization in small and medium-sized manufacturing environments is low.

[0006] Third, since light guide plate structures are generally composed of rigid plates, they lack flexibility and are difficult to apply to display cover structures or curved devices. This makes it difficult to meet the latest industry trends that require product lightweighting and design diversification.

[0007] Fourth, there is a problem where light extraction efficiency is low and viewing angle characteristics are limited due to structural limitations of the light guide pattern. In particular, the uniformity of screen brightness is reduced due to multilayer reflection and diffuse reflection, and reduced visibility due to external reflection may also occur.

[0008] Meanwhile, nanostructures found in the eyes of moths in nature have the property of minimizing light reflection, so moth-eye patterns mimicking this have begun to be applied to optical films. However, existing methods for forming moth-eye patterns required complex processes and high costs, which limited mass production.

[0009] In addition, existing light guide films required a separate attachment process during installation, and additional color films were needed to achieve color, which increased the complexity of the entire system.

[0010] Against this backdrop, there is an increasing demand for high-performance film structures that can replace existing photoguide technologies while being lightweight, flexible, and simultaneously securing adhesive properties and light efficiency. Prior art literature

[0011] Korean Registered Patent No. 2685647 (July 11, 2024) Korean Registered Patent No. 2649772 (March 15, 2024) The problem to be solved

[0012] The objective of the present invention is to provide an adhesive color light guide film equipped with a moth-eye micro pattern that maximizes light transmittance through the moth-eye micro pattern, integrates the color doping layer and the adhesive layer for easy installation, and enables the realization of various colors.

[0013] In addition, another objective of the present invention is to provide a method for manufacturing an adhesive color light guide film equipped with a moth-eye micro pattern that enables the formation of various moth-eye patterns suitable for mass production by improving existing complex processes. means of solving the problem

[0014] The adhesive color light guide film having a moth-eye micro pattern according to the present invention for achieving the above-mentioned purpose is characterized by comprising: a substrate film layer doped with a phosphor or quantum dot for color light conversion; a moth-eye pattern layer having a moth-eye micro pattern formed on the upper surface of the substrate film layer; and an adhesive layer positioned on top of the moth-eye pattern layer to be adhered.

[0015] At this time, the adhesive layer is formed as a plurality of dot layers that are evenly distributed at regular intervals and protruded to adhere to the adhesive, and when the adhesive is adhered to by the dot layers, it is preferable that the guided light is emitted by the phosphor or quantum dots doped in the substrate film by the dot layers that are adhered.

[0016] In addition, the method for manufacturing an adhesive color light guide film having a moth-eye micro pattern according to the present invention comprises the steps of: preparing a substrate film doped with a phosphor or quantum dot for color light conversion; forming a moth-eye pattern on one side of the substrate film; attaching a shielding film to the other side of the substrate film; forming an adhesive layer on one side of the substrate film on which the moth-eye pattern is formed; and attaching a release film to the adhesive layer.

[0017] At this time, the adhesive layer forming step is formed by a plurality of dot layers that are evenly distributed at regular intervals and formed as protrusions to adhere to the adhesive material, and when the adhesive material is adhered by the dot layers, it is preferable that the guided light is emitted by the phosphor or quantum dots doped in the substrate film by the adhered dot layers. Effects of the invention

[0018] According to the adhesive color light guide film equipped with a moth-eye fine pattern according to an embodiment of the present invention, the following effects are achieved.

[0019] First, light efficiency can be maximized by lowering the reflectance of light to 0.5% or less and improving the transmittance to 95% or more through a moth-eye micro pattern.

[0020] Second, various colors can be realized through the color doping layer, allowing light of the desired color to be obtained without a separate color film.

[0021] Third, the adhesive layer is integrated, making installation easy and increasing work efficiency.

[0022] Fourth, productivity and cost efficiency can be improved through various moth-eye pattern formation methods.

[0023] Fifth, it has high industrial utility as it can be applied to various fields such as displays, solar cells, LED lighting, illuminated advertisements, and electronic whiteboards. Brief explanation of the drawing

[0024] FIG. 1 is a cross-sectional view showing the layer structure of an adhesive color light guide film having a moth-eye micro pattern according to one embodiment of the present invention. Figure 2 is a photograph showing the structure of a moth-eye micro pattern according to the present invention. FIGS. 3 to 5 are manufacturing process diagrams of an adhesive color light guide film equipped with a moth-eye micro pattern according to one embodiment of the present invention. FIG. 6 is a schematic diagram showing a method for forming a moth-eye pattern using a roller coater according to the present invention. FIG. 7 is a schematic diagram showing a method for forming a moth-eye pattern using a knife roll coater according to the present invention. Specific details for implementing the invention

[0025] Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Note that in the accompanying drawings, identical components are indicated by the same reference numerals whenever possible. Furthermore, detailed descriptions of known functions and configurations that may obscure the essence of the invention will be omitted. For the same reason, some components in the accompanying drawings may be exaggerated, omitted, or schematically depicted.

[0026] FIG. 1 is a cross-sectional view showing the layer structure of an adhesive color light guide film having a moth-eye micro pattern according to one embodiment of the present invention, FIG. 2 is a photograph showing the structure of a moth-eye micro pattern according to the present invention, FIG. 3 to 5 are manufacturing process diagrams of an adhesive color light guide film having a moth-eye micro pattern according to one embodiment of the present invention, FIG. 6 is a schematic diagram showing a method for forming a moth-eye pattern using a roll coater according to the present invention, and FIG. 7 is a schematic diagram showing a method for forming a moth-eye pattern using a knife roll coater according to the present invention.

[0027] Referring to FIG. 1, the adhesive color light guide film having a moth-eye fine pattern according to the present invention comprises a base film layer (10), a moth-eye pattern layer (20), and an adhesive layer (30).

[0028] The substrate film layer (10) is a layer that serves as the main support for the film and is made of any one of the materials selected from general films (PET, PVC, PP, PE, etc.) and high-transparency PMMA, PC, TAC, and COP (cycloolefin polymer).

[0029] The above-mentioned substrate film layer (10) is doped with a phosphor or quantum dots for color light conversion.

[0030] The above-mentioned substrate film layer (10) may be integrally formed by doping a phosphor or quantum dot for color light conversion, or may be formed as a separate color light conversion layer.

[0031] When formed as a color light conversion layer, the thickness of the color light conversion layer is 10 to 30 μm.

[0032] At this time, urethane acrylate is used as the base resin and is contained in an amount of 60 to 70 wt%.

[0033] Phosphor or quantum dot particles are selected according to the desired color and are contained at 3–10 wt%. Red is CdSe / ZnS quantum dots or YAG:Eu 3+ is used, and green is CdSe / ZnS quantum dots or YAG:Ce 3+ It is used, and for blue, ZnS:Ag phosphor is used.

[0034] If the quantum dot content is too low, less than 3 wt%, there is an advantage of reduced energy consumption and cost savings, but there is a problem that the color purity and photostability are low, resulting in poor clarity.

[0035] If the quantum dot content exceeds 10 wt% and becomes too high, there is an advantage of high color purity and photostability, which makes it clearer, but there is a problem of increased energy consumption and increased costs.

[0036] TPO is used as the photoinitiator and is contained in an amount of 1 to 3 wt%. TPO is a representative type of photoinitiator that has the advantages of high initiation efficiency, no yellowing, and a relatively low cost.

[0037] If the content of the photoinitiator is too low, less than 1 wt%, the photosensitivity may decrease and the reaction rate may decrease.

[0038] If the content of the photoinitiator exceeds 3 wt%, the photosensitivity may be improved and the reaction speed may increase, but there is a disadvantage that the adhesion strength decreases.

[0039] The photodispersant uses silica nanoparticles and is contained in an amount of 0.5 to 1.5 wt%.

[0040] If the content of the light dispersant is too low, less than 0.5 wt%, the effect of uniformly dispersing light is reduced, making it difficult to achieve a uniform color.

[0041] If the content of the light dispersant exceeds 1.5 wt% and becomes too high, the effect of uniformly dispersing light increases, but there is a disadvantage that transparency decreases.

[0042] The remainder consists of cyclohexanone or butyl acetate as the solvent, containing 25 to 27 wt%.

[0043] The characteristics and thickness of each material are as follows.

[0044] PET (polyethylene terephthalate) has a thickness of about 50 to 175 μm, excellent mechanical strength, heat resistance, transparency of about 85 to 90%, and excellent chemical stability.

[0045] PVC (polyvinyl chloride) has a thickness of about 70 to 200 μm, is inexpensive, has excellent flame retardancy, has a transparency of about 80 to 88%, and has excellent chemical resistance.

[0046] PP (polypropylene) has a thickness of about 30 to 120 μm, is lightweight, has excellent moisture resistance, has a transparency of about 80 to 85%, has excellent chemical resistance, and has heat resistance.

[0047] PE (polyethylene) has a thickness of about 40 to 150 μm, excellent flexibility, a transparency of about 75 to 82%, excellent moisture resistance, and excellent low-temperature stability.

[0048] PMMA (acrylic) has a thickness of about 100 to 250 μm, a high transparency of over 93%, heat resistance, and excellent optical properties.

[0049] PC (polycarbonate) has a thickness of about 75 to 200 μm, is impact-resistant and heat-resistant, and has a high transparency of 90 to 92%.

[0050] TAC (triacetylcellulose) has a thickness of about 60 to 120 μm, low birefringence, high surface smoothness, and excellent optical isotropy.

[0051] COP (cycloolefin polymer) has a thickness of about 50 to 150 μm, low moisture absorption, high dimensional stability, a transparency of over 92%, and excellent chemical resistance.

[0052] The moth-eye pattern layer (20) is formed by roll coating, and its thickness is 1 to 2 μm.

[0053] A conical or pyramidal nanostructured moth-eye pattern is formed on the surface of the above moth-eye pattern layer (20).

[0054] The moth-eye pattern has a height of 200–400 nm, a pitch (spacing) of 150–300 nm, and a diameter (bottom) of 100–250 nm, and an aspect ratio of 1.5–2.5:1.

[0055] If the height of the moth-eye pattern exceeds 400 nm and becomes too high, the pattern shape may be deformed, the surface becomes soft and weak against impact, and there are disadvantages such as the manufacturing process being complex and the manufacturing cost being increased because a high aspect ratio moth-eye pattern must be formed.

[0056] If the height of the moth-eye pattern is too low, less than 200 nm, the difference in refractive index becomes small, which has the disadvantage of weakening the anti-reflection effect. The surface becomes susceptible to damage and wear, which can lead to a decrease in surface durability.

[0057] If the pitch of the moth-eye pattern is too narrow, less than 150 nm, it may be difficult to form the pattern or the durability of the pattern may be reduced.

[0058] If the pitch of the moth-eye pattern exceeds 300nm and becomes too wide, there is a problem in that the anti-reflection effect does not appear properly or the light is scattered.

[0059] If the diameter of the moth-eye pattern becomes too small, less than 100 nm, light reflection becomes severe.

[0060] If the diameter of the moth-eye pattern exceeds 250 nm and becomes too large, the light reflection effect weakens, leading to a problem where the light transmission efficiency decreases.

[0061] If the aspect ratio of the moth-eye pattern is too small, less than 1.5, the difference in refractive index becomes small, which weakens the light reflection effect and reduces light transmission efficiency. Additionally, the surface becomes susceptible to damage and wear, which can lead to reduced surface durability.

[0062] If the aspect ratio of the moth-eye pattern exceeds 2.5 and is too large, the anti-reflective effect is improved, but the pattern shape may be deformed, the surface becomes soft and weak against impact, and there are disadvantages such as the manufacturing process being complex and the manufacturing cost being increased because a high aspect ratio moth-eye pattern must be formed.

[0063] These moth-eye patterns have a hexagonal arrangement structure and serve to minimize light reflection and maximize transmittance.

[0064] The adhesive layer (30) is made of an acrylic adhesive and has a thickness of 15 to 25 μm. The composition of this layer is as follows:

[0065] The main component of the adhesive layer is an acrylic adhesive (2-EHA / AA / MAA terpolymer), and is contained in an amount of 87 to 90 wt%.

[0066] The solvent is a mixed solvent of 60 vol% ethyl acetate, 25 vol% acetone, and 15 vol% heptane, or an environmentally friendly mixed solvent of 70 vol% ethyl acetate and 30 vol% isopropyl alcohol is used.

[0067] The curing agent used is an isocyanate-based (HDI, TDI) and is contained in an amount of 3 to 10 wt%.

[0068] The additives used are 0.5~1.5 wt% silicone-based tackiness modifier, 0.5~1.5 wt% UV stabilizer, and 0.3~1.0 wt% antioxidant.

[0069] The release film (40) is a layer for protecting the adhesive layer (30) and is made of silicone-treated PET, PP, or PE material, with a thickness of 38 to 75 μm. The characteristics of each material are as follows.

[0070] The PET release film has a thickness of 38 to 50 μm and has excellent high smoothness and thermal stability.

[0071] PP release film has a thickness of 40 to 60 μm, is inexpensive, and has excellent flexibility.

[0072] PE release film has a thickness of 50 to 75 μm and has excellent moisture resistance and recyclability.

[0073] The silicone release agent is polydimethylsiloxane-based, and the application amount is 0.8 to 1.2 g / m².

[0074] Figure 2 is a photograph showing the structure of a moth-eye micro pattern according to the present invention.

[0075] Referring to Fig. 2, the moth-eye pattern consists of a hexagonal nanostructure, and this structure induces a gradual change in refractive index when light is incident from air onto the film, thereby minimizing reflection. This mimics the natural anti-reflective structure found in moth eyes.

[0076] FIGS. 3 to 5 are manufacturing process diagrams of an adhesive color light guide film equipped with a moth-eye micro pattern according to one embodiment of the present invention.

[0077] The method for manufacturing an adhesive color light guide film equipped with a moth-eye fine pattern according to the present invention comprises the following steps.

[0078] 1) Base film preparation step

[0079] A general film such as PET, PVC, PP, PE, and a substrate film (10) made of one of PMMA, PC, TAC, or COP are prepared (see FIG. 3 (a)).

[0080] 2) Moss-eye pattern formation step

[0081] A moth-eye pattern layer (20) is formed on one side of a substrate film (see Fig. 3(b)). As a method for forming the pattern, UV imprinting, thermal embossing, nanoimprint lithography, self-assembly pattern formation, coating-based pattern formation, or nano / micro coating methods may be used.

[0082] When using the UV imprinting method, the pattern is imprinted using a pattern mold and then cured by irradiating with UV light. When using the thermal embossing method, heat of 130–180°C is applied to a fine embossing copper plate roll to form a pattern on a thermoplastic substrate. When using the nano / micro coating method, a 3-roll coater, a knife roll coater, or a digital ejector may be used.

[0083] In the present invention, a moth-eye pattern layer (20) can be formed by a three-stage roll coater, and a pattern is formed on a thermoplastic substrate by applying heat of 130 to 180°C to a fine embossing copper plate roll by a thermal embossing method. FIG. 4 shows that the moth-eye pattern layer (20) is formed by a thermal embossing method.

[0084] 3) Shielding film adhesion step

[0085] A shielding film (15) is attached to the other side of the above-mentioned base film (10) (see (c) of FIG. 3).

[0086] The shielding film (15) is attached to the other side of the base film (10) and prevents light projected onto the base film (10) from being transmitted, thereby allowing light to be projected onto the side of the base film (10) where the shielding film (15) is not attached, thereby significantly increasing the light projection performance.

[0087] At this time, the method of attaching the shielding film (15) can be in two forms.

[0088] In the first form, when a moth-eye pattern layer (20) is formed by indenting one side of a base film (10) by heating and pressing with a heat roller, the heat used for heating by the heat roller also affects the base film (10) and the shielding film (15), so the bonding method is achieved by heat pressing using this heat. In FIG. 4 (b), when forming the moth-eye pattern layer (20), it is formed by a heat embossing method using a heat roller, and at this time, since the heat used for heating by the heat roller heat-bonds the base film (10) and the shielding film (15), it shows that the bonding is achieved without using an adhesive.

[0089] In the second form, when a moth-eye pattern layer (20) is formed on the upper surface of a base film (10) by transfer using a roller coater, an adhesive is applied to the other side of the base film (10) where the moth-eye pattern layer (20) is not formed, thereby bonding the base film (10) and the shielding film (15). FIGS. 3 and 5 show that when bonding the base film (10) and the shielding film (15), an adhesive is applied between them to bond them.

[0090] 4) Adhesive layer formation step

[0091] An adhesive layer (30) is formed on the upper surface of a moth-eye pattern layer (20) formed on one side of a substrate film (10) (see (d) of FIG. 3).

[0092] At this time, it is preferable that the adhesive layer formation step be formed into a plurality of dot layers that are evenly distributed at regular intervals and formed as protrusions to adhere to the adhesive material.

[0093] The above dot layer is adhered to the adhesive, and the light guided by the dot layer is emitted by the phosphor or quantum dots doped in the substrate film (10).

[0094] There are two types of methods for forming an adhesive layer (30) consisting of a plurality of dot layers on top of a moth-eye pattern layer (20) formed on one side of a substrate film (10).

[0095] In the first form, a release film coated with an adhesive consisting of a dot layer is laminated, so that when the release film is removed, the adhesive layer (30) coated on the release film is transferred onto the upper surface of the moth-eye pattern layer (20) formed on one side of the base film (10). In this case, the step of attaching the release film described later is omitted, and when the release film (40) is removed, the adhesive layer (30) coated on the release film is transferred onto the upper surface of the moth-eye pattern layer (20) formed on one side of the base film (10) (see (f) in FIG. 5).

[0096] In the second form, to apply an adhesive layer of the dot layer, a roller having a plurality of dot layers formed indentations is used to apply an adhesive, and the dot layer is directly coated on the upper surface of the moth-eye pattern layer (20) formed on one side of the base film (10) (see FIG. 3 (d) and FIG. 4 (c)). After coating the dot layer, a release film is laminated to protect the dot layer.

[0097] Die coating (rib spacing: 180–220 μm) or comma coating (20–24 bar) is used as the coating method. The coating thickness is 30–40 μm in the wet state and 15–25 μm after drying.

[0098] The coating conditions are a coating speed of 10–20 m / min, a coating viscosity of 2,000–3,000 cPs (25°C, Type B viscometer), and a coating pressure of 0.15–0.25 MPa (for die coating). The drying conditions are 80°C (60 seconds) for the first drying step, 100–120°C (120–180 seconds) for the second drying step, and 130°C (30 seconds) for the third drying step, and the curing conditions are 60°C for 24–48 hours.

[0099] 5) Release film attachment step

[0100] A release film (40) is attached to the adhesive layer (30) (see (e) of FIG. 3).

[0101] The lamination method uses a nip roller compression method and proceeds at a lamination temperature of 40~50°C, a lamination pressure of 0.5~1.0 kg / cm², and a lamination speed of 10~15 m / min.

[0102] FIG. 6 is a schematic diagram showing a method for forming a moth-eye pattern using a roller coater according to the present invention.

[0103] Referring to Fig. 6, the method for forming a moth-eye pattern using a roller coater is a method of precisely dispersing and coating a coating solution containing nanoparticles or pattern-forming additives. Effective dispersion is induced by finely adjusting the spacing between the three rollers (20–80 μm) and setting the differential speed ratio to 1:2:4.

[0104] The coating solution composition consists of an acrylate or epoxy-based resin (60–70%), silica or TiO₂ nanoparticles (5–10%), a fluorine-based additive (1–3%), and the remainder is a solvent. After coating, the solvent is evaporated in a controlled environment (temperature gradient 20–40°C), and the pattern is stabilized through UV curing (300–500 mJ / cm²). This method controls the spontaneous phase separation phenomenon to form a moth-eye pattern in the range of 200–500 nm.

[0105] FIG. 7 is a schematic diagram showing a method for forming a moth-eye pattern using a knife roll coater according to the present invention.

[0106] Referring to Fig. 7, the method for forming a moth-eye pattern using a knife roller coater is a method that induces phase separation by precisely controlling the coating thickness with a knife roller.

[0107] Meanwhile, the embodiments of the present invention disclosed in this specification and drawings are merely specific examples provided to facilitate the explanation of the technical content of the present invention and to aid in understanding the invention, and are not intended to limit the scope of the invention. It is obvious to those skilled in the art that other variations based on the technical concept of the present invention are possible in addition to the embodiments disclosed herein. Explanation of the symbols

[0108] 10: Substrate film layer 15: Shielding film 20: Moss Eye Pattern Layer 30: Adhesive layer 40: Release film

Claims

Claim 1 delete Claim 2 delete Claim 3 A step of preparing a thermoplastic substrate film doped with a phosphor or quantum dots for color light conversion; a step of forming a moth-eye pattern on one side of the substrate film; a step of adhering a shielding film to the other side of the substrate film; a step of forming an adhesive layer on one side of the substrate film on which the moth-eye pattern is formed; and a step of attaching a release film to the adhesive layer. The method includes, wherein the adhesive layer forming step is formed by a plurality of dot layers that are evenly distributed at regular intervals and formed as protrusions to adhere to an adhesive, and when the adhesive is adhered to by the dot layers, the guided light is emitted by the phosphor or quantum dots doped into the substrate film by the adhered dot layers, and the moth-eye pattern formed during the moth-eye pattern forming step is conical, has a height of 200 to 400 nm, a pitch of 150 to 300 nm, a diameter of 100 to 250 nm, an aspect ratio of 1.5 to 2.5:1, and has a hexagonal arrangement structure, and the adhesive layer forming step is formed by applying an adhesive using a roller having a plurality of dot layers formed as indentations and directly coating the dot layers on top of the moth-eye pattern layer formed on one surface of the substrate film, and the moth-eye pattern forming step is formed by applying heat to a fine embossing copper plate roll and pressing a thermoplastic A method for manufacturing an adhesive color light guide film having a moth-eye fine pattern, wherein a moth-eye pattern is formed by a heat embossing method for forming a pattern on a substrate film, and the shielding film bonding step is characterized by using heat applied to the copper plate roll during the moth-eye pattern formation step to heat-bond the other side of the substrate film and the shielding film without using an adhesive. Claim 4 delete

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