KR100973599B1 - Optical film eliminating protective films and Preparing thereof - Google Patents

Abstract

In the present invention, in the optical film, a lenticular functional layer is formed on the surface of the optical film, the upper sheet is adhered to the upper surface of the lenticular functional layer of the optical film to form an adhesive interface, the lens type except the adhesive interface Provided are an optical film having a protective film formed thereon with an air layer formed on an upper portion of a functional layer and a lower portion of an upper sheet, and a method of manufacturing the same.

Description

Optical film eliminating protective film and preparing method thereof

The present invention relates to an optical film of a liquid crystal display device and a method for manufacturing the same, and more particularly, to an optical film and a method for manufacturing the same that do not require a protective film.

Recently, various flat panel display devices have been developed. The flat panel display devices include liquid crystal displays (LCDs), plasma display panels (PDPs), and field emission displays (FEDs). In addition, studies are being actively conducted to improve the display quality of such flat panel displays.

In particular, the liquid crystal display device, unlike other display elements, is a liquid crystal material injected between the TFT substrate and the color filter, not a light emitting material that emits light, but a light receiving material that displays the light on the screen by controlling the amount of light from the outside. A separate device for illuminating the panel, i.e., a backlight unit, is necessary.

The backlight unit includes a mold frame having a storage space formed thereon and a reflective sheet reflecting light toward the liquid crystal display panel, a light guide plate installed on an upper surface of the reflective sheet for guiding light, and the light guide plate and the storage space between sidewalls. A lamp unit installed in the light emitting unit, an optical sheet stacked on an upper surface of the light guide plate to diffuse and collect light, and installed on an upper part of the mold frame to cover an area from the predetermined position of the edge of the liquid crystal display panel to the side of the mold frame. Consists of a top chassis.

1 is a cross-sectional view showing the configuration of a conventional liquid crystal display device.

In FIG. 1, a conventional liquid crystal display device 30 includes a backlight unit 20 for generating light and a display unit provided above the backlight unit 20 and receiving light from the backlight unit 20 to display an image. 10) is included.

The backlight unit 20 includes a lamp unit 24 for generating light and a light guide unit for guiding the light generated by the lamp unit 24 to the liquid crystal display panel 12.

In addition, the display unit 10 includes the liquid crystal display panel 12, an upper polarizing plate 11, and a lower polarizing plate 12 positioned above and below the liquid crystal display panel 12. The liquid crystal display panel 12 includes a TFT substrate on which electrodes are formed, color filter substrates 12a and 12b, and a liquid crystal layer injected between the TFT substrate and color filter substrates 12a and 12b.

In addition, the lamp unit 24 includes a lamp 24a for generating light and a lamp reflector 24b surrounding the lamp, and the light generated from the lamp 24a is incident on the light guide plate 22. The reflecting plate 24b increases the amount of light incident on the light guide plate 22 by reflecting the light generated from the lamp 24a to the light guide plate 22.

The light guide unit includes a reflector 23, a light guide plate 22, and an optical sheet 21, and the light guide plate 22 is provided at one side of the lamp unit 24 to guide light from the lamp unit 24. Play a role.

In addition, the lower part of the light guide plate 22 has a reflector 23 for reflecting light leaked from the light guide plate 22 back to the light guide plate, and the upper part of the light guide plate 22 has an efficiency of light guided by the light guide plate 22. A plurality of optical sheets 21 are provided to improve the performance. Specifically, the optical sheet 21 is composed of a diffusion sheet 21c, a prism sheet 21b, a protective sheet 21a, and sequentially stacked on the light guide plate 22.

The diffusion sheet 21b scatters the light incident from the light guide plate 22 to uniform the luminance distribution of the light, and the prism sheet 21b has a triangular prism repetitively formed on the upper surface of the prism sheet 21b. The light diffused by the diffusion sheet 21c is focused in a direction perpendicular to the plane of the liquid crystal display panel 12. As a result, most of the light passing through the prism sheet 21b is transferred to the liquid crystal display panel. It proceeds perpendicular to the plane of 12) and has a uniform luminance distribution. In addition, the protective sheet 21a provided on the prism sheet 21b serves to protect the surface of the prism sheet 21b.

On the other hand, the prism sheet is composed of a body portion into which the light diffused by the light guide plate and the diffusion sheet is first introduced, and an isosceles triangular pillar shape to allow the diffused light to be uniformly progressed, and a protrusion having a rounded end portion.

The prism sheet is characterized in that the smooth surface of the body portion is easily scratched even by a slight impact, and in the case of protrusions, scratches are frequently caused by bending or slight friction.

Therefore, the protective films 210 and 230 are adhered to both sides of the prism sheet to prevent scratches during the production or transportation of the prism sheet, thereby preventing damage due to scratching of the prism sheet until assembly of the backlight unit. It was. However, the adhesion of such a protective film has to be carried out during the production process, there is a problem that the production cost is also expensive. (See FIG. 1B)

Accordingly, by performing the role of the existing prism sheet, the same effect as the existing optical sheet, such as brightness is shown, it is desired to reduce the production cost of the optical sheet to suppress the scratch occurrence of the prism sheet surface.

In order to solve the above problems, an object of the present invention is to provide an optical film and a method of manufacturing the same, which can reduce the production cost and process automation by using a protective film in the optical film.

In addition, an object of the present invention is to provide an optical film and a method for manufacturing the same which can improve productivity by forming two or more optical films into an integrated optical film.

In addition, the present invention is to provide a composite integrated optical film and its manufacturing method without deterioration of optical properties such as brightness.

In order to achieve the above object, in the present invention, in the optical film, a lens-like functional layer is formed on the surface of the optical film, the upper sheet is adhered to the upper portion of the lens-type functional layer of the optical film to form an adhesive interface In addition, the present invention provides an optical film from which a protective film having an air layer formed on an upper portion of a lens-type functional layer and a lower portion of an upper sheet except the adhesive interface is removed.

In another aspect, the present invention, in the optical film, to protect the optical film, without using a protective film on the surface or the back, forming an uneven portion on the surface or the back of the optical film to remove the protective film imparted scratch resistance Provide a film.

In another aspect, the present invention provides an optical film is removed without the use of a protective film on the back surface of the optical film, a protective film provided with scratch resistance by further forming a fine uneven portion on the back surface of the optical film.

In another aspect, the present invention provides an optical film from which the protective film of the prism shape is removed.

In another aspect, the present invention provides an optical film from which the protective film of the prism is 150 to 230㎛ removed.

In another aspect, the present invention provides an optical film from which the protective film of the height of the prism is 70 to 120㎛ removed.

In another aspect, the present invention provides an optical film from which the protective film containing the copolyester and polycarbonate as a blend or a composition comprising 10 to 90% by weight of copolyester and 10 to 90% by weight of polycarbonate.

In the present invention, the film is methyl methacrylate, ethyl methacrylate, isobutyl methacrylate, normal butyl methacrylate, normal butyl methyl methacrylate, acrylic acid, methacrylic acid, hydroxyethyl methacrylate, hydride Monomer selected from oxypropyl methacrylate, hydroxyethyl acrylate, acrylamide, metalolacrylamide, glycidyl methacrylate, ethyl acrylate, isobutyl acrylate, normal butyl acrylate and 2-ethylhexyl acrylate It provides an optical film from which at least one protective film selected from the group consisting of a homopolymer, copolymer or terpolymer, polyethylene, polystyrene, polypropylene, acryl and olefin copolymers, and silicone-based spherical particles.

In the present invention, the film is methyl methacrylate, ethyl methacrylate, isobutyl methacrylate, normal butyl methacrylate, normal butyl methyl methacrylate, acrylic acid, methacrylic acid, hydroxyethyl methacrylate, hydride Monomer selected from oxypropyl methacrylate, hydroxyethyl acrylate, acrylamide, metalolacrylamide, glycidyl methacrylate, ethyl acrylate, isobutyl acrylate, normal butyl acrylate and 2-ethylhexyl acrylate Optical protective film further comprising one or more selected light diffusing particles made of a homopolymer, a copolymer or a terpolymer, polyethylene, polystyrene, polypropylene, acrylic and olefin copolymers and beads and silicone spherical particles Provide a film.

In another aspect, the present invention provides a method of manufacturing an optical film, comprising the steps of: melt extruding a film material; The melt-extruded film has a lens-like functional layer on the surface, and optionally, the back surface is indented fine shape; Optionally applying a pressure-sensitive adhesive on the bonding surface of the top sheet to bond the inscribed film with a previously prepared top sheet; And optionally, applying the pressure-sensitive adhesive-coated upper sheet and the stamped film to a bonding roll at the same time and bonding them together at an adhesive interface to provide a method of manufacturing an optical film from which a protective film has been removed.

In another aspect, the present invention provides a method for producing an optical film from which the protective film of the prism shape is removed.

In another aspect, the present invention provides a method for producing an optical film from which the protective film of the prism is 150 to 230㎛ removed.

In another aspect, the present invention provides a method for producing an optical film from which the protective film of the height of the prism is 70 to 120㎛ removed.

In another aspect, the present invention provides a method for producing an optical film from which the protective film formed by the uneven shape is formed by matte roll processing.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. First, it should be noted that in the drawings, the same components or parts denote the same reference numerals as much as possible. In describing the present invention, detailed descriptions of related well-known functions or configurations are omitted in order not to obscure the subject matter of the present invention.

The terms " about ", " substantially ", etc. used to the extent that they are used herein are intended to be taken to mean an approximation to or in the numerical value of the manufacturing and material tolerances inherent in the meanings mentioned, Accurate or absolute numbers are used to help prevent unauthorized exploitation by unauthorized intruders of the referenced disclosure.

As used herein, the term "film" is used to mean a film, sheet, plate, or the like having a predetermined width and thickness. In addition, the term "lens functional layer" is used to mean a prism-shaped functional layer, a lenticular, a hemispherical lens, or the like.

In describing the optical film according to the present invention, a prism sheet will be described as a non-limiting example, but is not limited thereto.

FIG. 2 illustrates a prism sheet 100 according to an exemplary embodiment of the present invention, and may form an uneven portion 130 on the back surface of the sheet.

As described above, the prism sheet is attached to a protective film on the surface and / or the rear surface for the next process after manufacture to prevent scratches or damage caused by the punching process performed when assembling the backlight unit. . In general, when a defect occurs in the sheet during a process such as sheet manufacturing or punching, the sheet should be discarded. In this case, the protective films 210 and 230 are also discarded together, which causes a cost increase.

As a method of improving the problem, the present invention forms a fine concave-convex portion 130 on the back surface of the sheet 100 to express optical properties and at the same time increase the surface hardness to prevent scratches due to impact. The fine concave-convex portion 130 may be formed by various methods, and may be formed by a matte roll process as a non-limiting example.

3 and 4 illustrate a prism sheet 100 according to another preferred embodiment of the present invention, which simultaneously realizes the complexing of an optical film while preventing the scratch of the prism portion 110 formed on the surface of the sheet. That is, the prism sheet is integrated with a diffusion film, a protective sheet, a lenticular film, and the like, which can be stacked on the prism sheet 100. Here, the protective sheet is distinguished from the protective films 210 and 230 and refers to the protective sheet of the backlight unit.

3 is a structure in which the top sheet 300 is coupled, and FIG. 4 shows a form in which the top sheet is coupled to the lenticular sheet 400. Here, the top sheet may be a diffusion film, a protective sheet, a lenticular sheet and the like, which is just one example and does not limit the type and material of the top sheet added to the top of the prism sheet. An adhesive interface 600 is present at the upper portion of the prism portion 110 or the lower portion of the upper sheet 300 of the prism sheet 100, such that the prism sheet 100 and the upper sheet 300 are coupled by the adhesive force of the adhesive interface. In addition, the identification code 500 is formed for the functional expression of the optical film as an air layer.

In the actual prism sheet, the shape of the vertex of the prism portion is not always maintained at an acute angle, and the shape of the vertex is kept rounded smoothly due to the influence of residual stress. In this case, the adhesive interface may have a surface contact.

In addition, the laminated structure between the optical films is required to form an air layer therebetween, in the case of the optical film of the present invention serves as an air layer 500 formed between the prism portion 110 between the top sheet 300 and the prism sheet 100. For this purpose, the pitch of the prism portion 110 (distance between vertices and vertices) may be 150 to 230 µm and the height (vertical distance from the vertex to the base) may be 70 to 120 µm. The above range is for securing an air layer that performs an optical function as a prism and reflects refraction.

5 and 6 show another embodiment combining the embodiment of FIG. 2 and the embodiment of FIGS. 3 and 4. In this embodiment, the surface and back protection film may be removed. When the optical films are integrally manufactured as in the present embodiments, the backlight manufacturing process may be automated.

On the other hand, the material of the optical film may be made of a blend or composition of copolyester and polycarbonate, and may specifically include 10 to 90% by weight of copolyester and 10 to 90% by weight of polycarbonate.

The copolyester may be terephthalic acid, naphthalenedicarboxylic acid, cyclohexanedicarboxylic acid or a mixture thereof as the acid component, and ethylene glycol and 1,4-cyclohexanedimethanol (CHDM) may be used as the glycol component. . Non-limiting examples of suitable copolyesters include poly (1,4-cyclohexylenedimethylene terephthalate) (PCT), poly (1,4-cyclohexylenedimethylene naphthalenedicarboxylate) (PCN), poly (1,4-cyclohexylenedimethylene 1,4-cyclohexanedicarboxylate) (PCC) can be used.

Meanwhile, the polycarbonate-based non-limiting example is preferably an aromatic polycarbonate and more preferably may be a polycarbonate including bisphenol-A [2,2-bis (4-hydroxyphenyl) propane].

In general, as the material of the optical film, polycarbonate (PC), acrylic (particularly PMMA, Poly Methyl Meta Acrylate), etc., are used. Physical properties of general PC or PMMA series have a high degree of stiffness (stiffness, stiffness) and a brittle property, making it difficult to groove or hole. Therefore, punching is difficult and only possible as cutting. However, in the hole processing there is a problem that is difficult to implement even in the cutting process.

Therefore, only the material of the optical film according to an embodiment of the present invention has the advantage that the processability can be secured. In addition, the material has a relatively low process moisture content has a feature that can maintain shape stability even at high humidity.

Meanwhile, the optical film according to the present invention may further include light diffusing particles. Since the light diffusing particles should be compatible with a binder (resin) containing particles, organic particles having a similar refractive index to materials and spherical shapes having a low refractive index may be used. The silicon particles were examined and used, and inorganic particles having a material refractive index of 1.50-1.80 can also be used. Particularly, the particle selection to be used is advantageous for solving the problem such as showing the bright line due to the spherical particles whose refractive index difference is 0.1 to 0.2 from the material to increase the shielding ability, and can maximize the diffusion effect with a relatively small particle amount. It is very advantageous.

The refractive index of the diffusing agent particles used increases the light diffusing effect as the difference between the material and the refractive index is larger, but when the refractive index difference is too large, it is disadvantageous in terms of increasing the luminance, so that the proper refractive index difference is obtained and sometimes similar to the material-refractive index particles. It is preferable to use combining the particle | grains with a big refractive index difference.

Non-limiting examples of light diffusing particles that can be used in the present invention include methyl methacrylate, ethyl methacrylate, isobutyl methacrylate, normal butyl methacrylate, normal butyl methyl methacrylate, acrylic acid, methacrylic acid, Hydroxyethyl methacrylate, hydroxypropyl methacrylate, hydroxyethyl acrylate, acrylamide, metalolacrylamide, glycidyl methacrylate, ethyl acrylate, isobutyl acrylate, normal butyl acrylate and 2 Homopolymers, copolymers or terpolymers of monomers selected from ethylhexyl acrylate, beads made from copolymers of polyethylene, polystyrene, polypropylene, acrylics and olefins, and silicone-based spherical particles may be used. Preferably, the material is spherical particles between 1 micron and 10 microns having a refractive index difference of about 0.1 to about 0.2. Spherical organic particles having such a refractive index difference can be easily dispersed in the resin because they have densities similar to those of the material used in the present invention (about 1.10 to 1.30 g / cm < 3 >).

The light diffusing particles used in the present invention may use different ones in type and / or size. For example, light diffusion efficiency can be enhanced by mixing two or more kinds of particles having a difference in refractive index rather than a single type. In addition, light diffusing efficiency may be increased by using particles having similar refractive indices and different sizes, and by applying porous particles, the brightness may be increased while maximizing light diffusing efficiency after assembling the backlight unit.

Using particles of uniform particle size requires a large amount of particles to produce a predetermined light diffusing effect, which results in not only economic inefficiency, but also lowering the overall light transmittance. According to one embodiment of the present invention, the size of the light diffusing particles can be used to increase the light diffusion effect while reducing the content of particles by using particles of two sizes of 20 to 30 microns and 1-15 microns.

The light diffusing particles may be used at 0.5 to 30% by weight, preferably 1 to 15% by weight, based on the total weight of the binder. For example, when it is 0.5 weight% or less, a predetermined light-diffusion effect cannot be acquired. On the other hand, when it exceeds 30 weight%, light transmittance falls and particle dispersibility falls and uniform particle dispersion | distribution is not obtained.

Figure 7 shows a manufacturing process chart of the optical film according to the present invention. First, if the prism sheet is described as an example, the material formed of the material is subjected to the step of melt extrusion (extrusion step). The melt-extruded film is stamped into a prism shape on the surface and a fine iron shape on the back surface. In this case, the engraving may be formed while passing through the engraving roll (drawing step). Meanwhile, the film in which the prism shape is imprinted is combined with the pre-prepared top sheet, and the adhesive surface of the top sheet is coated with a technique such as laminating in a range that does not impair optical properties (application step). The top sheet and prism sheet to which the pressure-sensitive adhesive is applied are simultaneously put into a bonding roll and joined at the adhesive interface to be integrated (bonding step).

Meanwhile, if the embodiment shown in FIG. 2 is selectively implemented, only the lifting step may be performed. If the embodiment shown in FIGS. 3 and 4 is implemented, the irregular shape may not be implemented.

The optical film and its manufacturing method according to the present invention has the advantage of not having to use the protective film used on the surface and / or the back of the optical film has the effect of reducing the production cost and the manufacturing of the protective film conventionally made by hand during the backlight unit manufacturing The elimination process can be omitted, thereby improving the process automation and productivity.

In addition, the optical film and the method of manufacturing the same according to the present invention can integrate two or more optical films, thereby omitting a process of stacking a plurality of optical films individually during manufacturing of the backlight unit, thereby improving productivity.

In addition, the optical film and the manufacturing method thereof according to the present invention is characterized in that productivity is improved without compromising optical characteristics such as luminance as an optical film.

Hereinafter, embodiments of the present invention will be described in detail.

Example 1

A 1: 1 ratio of a polycarbonate resin containing a polyester resin mainly containing 1,4-cyclohexanedicarboxylic acid and bisphenol-A [2,2-bis (4-hydroxyphenyl) propane] The phosphate-based heat stabilizer was blended to 0.3 wt% based on the total content. Thereafter, the resin was prepared in a 1.0 mm thick film through a screw coextrusion facility at 270 ℃.

At this time, the surface was extruded and stamped into a prism shape, but the shape of the prism was formed with a pitch of 190 μm and a height of 90 μm, and the back surface was carved into a fine concavo-convex shape.

Meanwhile, a pressure-sensitive adhesive was applied to the back surface of the diffusion film to be stacked on the prepared prism sheet, and the prism sheet and the light diffusion plate were bonded to prepare an integrated optical film, and five samples were prepared.

Comparative Example 1

In the same manner as in Example 1, but without forming fine irregularities on the back surface of the prism sheet, the diffusion film was laminated on the upper portion of the prism sheet.

* Test Methods

1. Transmittance (TT) and haze (Haze): Measured by ASTM D1003 method using NIPPON DENSHOKU 300A analyzer.

2. Luminance: Measure the film on the stage equipped with TOPCON BM-7 under the conditions of 16.5V and Dimming value of 2.8V with CCFL voltage mounted on backlight unit (diffusion plate-diffusion film-prism-diffusion film). .

Table 1 below shows the results of testing optical characteristics such as luminance of each of Examples and Comparative Examples. As shown in the following table, the optical properties of the optical film according to the present invention were not significantly reduced.

division Test result transparency(%) Cloudiness (%) Luminance (cd / m ² ) Example 1 Sample 1 11.1 83.8 12405 Sample 2 11.2 83.8 12200 Sample 3 11.4 84.1 12200 Sample 4 11.4 84.0 12320 Sample 5 11.1 83.9 12230 Average 11.24 83.92 12275 Comparative Example 1 11.3 84.2 12250

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the inventions. It will be clear to those who have knowledge of.

1a and 1b is a conceptual view of a protective film applied to the backlight unit and the optical film according to the prior art.

2 to 6 is a cross-sectional conceptual view of an optical film from which a protective film is removed according to an embodiment of the present invention.

Figure 7 is a manufacturing process of the optical film is removed protective film according to an embodiment of the present invention.

100: prism sheet 110; Prism part

130: uneven portion 210, 230; Protective film

300: diffusion sheet 400: lenticular sheet

500: air layer 600: adhesive interface

Claims (14)

In the optical film, A lens-type functional layer is formed on the surface of the optical film, The upper sheet is adhered to the upper portion of the lens-type functional layer of the optical film to form an adhesive interface, An optical film having a protective film having an air layer formed on the upper portion of the lens-type functional layer and the lower portion of the upper sheet except the adhesive interface. In the optical film, To protect the optical film without using a protective film on the surface or the back, An optical film from which a protective film provided with scratch resistance is formed by forming an uneven portion on the surface or the back of the optical film. The method of claim 1, Without using a protective film on the back of the optical film, An optical film from which a protective film provided with scratch resistance is further formed by further forming an uneven portion on the back surface of the optical film. The method according to claim 1 or 3, The lens-type functional layer is an optical film from which a protective film of a prism shape is removed. The method of claim 4, wherein The prism has a pitch of 150 to 230㎛ protective film is removed optical film. The method of claim 4, wherein The prism has a height of 70 to 120㎛ protective film removed optical film. The method according to any one of claims 1 to 3, The film is an optical film from which the protective film containing 10 to 90% by weight of copolyester and 10 to 90% by weight of polycarbonate as a blend or composition of copolyester and polycarbonate. The method according to any one of claims 1 to 3, The film is methyl methacrylate, ethyl methacrylate, isobutyl methacrylate, normal butyl methacrylate, normal butyl methyl methacrylate, acrylic acid, methacrylic acid, hydroxyethyl methacrylate, hydroxypropyl methacrylate Homopolymers of monomers selected from latex, hydroxyethyl acrylate, acrylamide, metalolacrylamide, glycidyl methacrylate, ethyl acrylate, isobutyl acrylate, normal butyl acrylate and 2-ethylhexyl acrylate Optical film wherein at least one protective film selected from the group consisting of beads or silicone-based spherical particles made of a copolymer or terpolymer, polyethylene, polystyrene, polypropylene, acryl and olefin copolymer. The method according to any one of claims 1 to 3, The film is methyl methacrylate, ethyl methacrylate, isobutyl methacrylate, normal butyl methacrylate, normal butyl methyl methacrylate, acrylic acid, methacrylic acid, hydroxyethyl methacrylate, hydroxypropyl methacrylate Homopolymers of monomers selected from latex, hydroxyethyl acrylate, acrylamide, metarollacrylamide, glycidyl methacrylate, ethyl acrylate, isobutyl acrylate, normal butyl acrylate and 2-ethylhexyl acrylate, An optical film from which the protective film further comprises at least one light diffusing particle made of a copolymer or a terpolymer, polyethylene, polystyrene, polypropylene, acryl and olefin-based beads and silicon-based spherical particles. In the manufacturing method of the optical film, Melt extruding the film material; The melt-extruded film has a lens-like functional layer on the surface, and optionally, the back surface is indented fine shape; Applying an adhesive to the bonding surface of the top sheet to bond the film having the shape stamped with a previously prepared top sheet; And A method of manufacturing an optical film from which a protective film has been removed, comprising: integrating the adhesive-coated upper sheet and the stamped film into a bonding roll at the same time so as to be bonded at an adhesive interface. The method of claim 10, The lens type functional layer is a method of manufacturing an optical film from which a protective film of a prism shape is removed. The method of claim 11, The prism pitch is 150 to 230㎛ manufacturing method of the optical film from which the protective film is removed. The method of claim 11, The height of the prism is 70 to 120㎛ method of manufacturing an optical film from which the protective film is removed. The method of claim 10, The micro-convex shape is a manufacturing method of an optical film from which the protective film formed by matte roll processing is removed.

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