KR100864319B1 - Light diffuser plate for LCD back light unit - Google Patents

Abstract

The present invention relates to a light diffusing plate for a liquid crystal display backlight unit, and more particularly, to diffuse uneven light generated from a plurality of cold cathode fluorescent lamps mounted on a liquid crystal display backlight without including a light diffusing agent. The present invention relates to a diffuser plate having a multilayer structure having a resin layer having a structure and a resin layer containing only a small amount of a light diffusing agent.

According to an embodiment of the present invention, a light diffusing plate for a liquid crystal display device backlight unit having a surface shape imparted with a light scattering function and having excellent heat resistance includes a methacrylic acid-styrene copolymer and a methyl methacrylate methyl-styrene copolymer. 0.1 to 10 parts by weight of a siloxane light diffusing agent having an average particle diameter of 1 to 20 µm and 0.1 to 10 parts by weight of an acrylic light diffusing agent having an average particle diameter of 1 to 20 µm, Substrate layer comprising; A lower coating layer laminated on a surface on which light of the base layer is incident, made of methyl methacrylate-styrene copolymer resin, and having a diffuse reflection pattern formed on a surface thereof; And an upper coating layer laminated on a surface on which light of the base layer is incident, made of methyl methacrylate-styrene copolymer resin, and having a reverse lenticular pattern formed on a surface thereof.

Liquid Crystal Display, Backlight Unit, Light Diffusion Plate, Reverse Lenticular Pattern, Diffuse Reflection Pattern

Description

Light diffuser plate for LCD back light unit

1 is a cross-sectional view showing a direct backlight unit.

2 is a cross-sectional view illustrating a light diffusion plate for a backlight unit of a liquid crystal display according to an exemplary embodiment of the present invention;

3 is a perspective view illustrating a light diffusion plate for a backlight unit of a liquid crystal display according to an exemplary embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

20, 21: light diffusion plate 200: substrate layer

210: upper coating layer 212: reverse lenticular pattern

220: lower coating layer 222: diffuse reflection pattern

230: light source

The present invention relates to a light diffusing plate for a liquid crystal display backlight unit, and more particularly, to diffuse uneven light generated from a plurality of cold cathode fluorescent lamps mounted on a liquid crystal display backlight without including a light diffusing agent. The present invention relates to a diffuser plate having a multilayer structure having a resin layer having a structure and a resin layer containing only a small amount of a light diffusing agent.

A liquid crystal display device is not a self luminescence device such as a plasma display panel (PDP) or an organic light emission diode (OLED), but a liquid crystal display according to a predetermined signal when a surface light is incident on the rear surface of the liquid crystal display device. It is a device that displays the passing light by adjusting the opening / closing of the passage where the light moves according to the change.

As such, since the liquid crystal display is not a self-luminous element, the liquid crystal display requires a device called a backlight unit on its rear surface. The backlight unit of the liquid crystal display may be divided into an edge type and a direct type. The double edge type is mainly used for a notebook computer or a desktop computer monitor, and the direct type is mainly used for a large area such as an LCD TV.

1 is a cross-sectional view showing a direct backlight unit.

As shown in FIG. 1, the direct backlight unit 10 includes a fluorescent lamp 100 for generating light, a reflector 110 for reflecting the generated light in a direction in which the panel is located, and a light diffusion plate 120. Include.

The reason why the backlight unit 10 illustrated in FIG. 1 is called a direct type is that the fluorescent lamp 100 is not positioned at the side of the backlight unit 10 but is perpendicular to the surface where the actual image information is displayed. Because it is located.

There is a light diffusion plate 120 in the direct type backlight unit 10, the light diffusion plate 120 is scattered (scattering) the light generated from the fluorescent lamp 100 to the surface uniform light in the entire panel It plays the role of making it.

The light diffusion plate 120 is mainly a transparent thermoplastic resin such as methacrylic resin, styrene resin, cyclic olefin resin, polycarbonate resin as the base resin. In addition, the optical diffuser 120 is manufactured by adding a light diffusing agent to the base resin. The light diffusing agent transmits light such as direct light or fluorescent light with high transmittance and hiding power such that the light source is not visually identified. And light diffusion effect to diffuse light.

Generally used as a light diffusing agent, inorganic or organic materials having a difference in refractive index between 0.02 and 0.13 are used. As the inorganic fine particles, calcium carbonate, barium sulfate, titanium dioxide, aluminum hydroxide, silica, glass, talc, There are mica, white carbon, magnesium oxide, zinc oxide, and the like, and as the organic fine particles, silicon-based, teflon-based, acrylic-based, styrene-based, and the like are used.

Conventional techniques for such a light diffusion plate include the following.

Japanese Laid-Open Patent Publication No. 9-31288 discloses a light diffusion plate composition in which precipitated calcium carbonate is added having a hexahedral structure as a light diffusing agent and having an average particle diameter of 1 to 15 µm using a methacrylic resin as a base resin. Korean Patent Laid-Open No. 11-35779 discloses a light diffusion plate composition in which an inorganic light diffusing agent such as barium sulfate, calcium carbonate, and talc is added as a base resin.

However, when the light diffusing agent in the form of particles is added in manufacturing the light diffusing plate as described above, when the particles are agglomerated with each other and light generated from the light source is transmitted or diffused, the spots are spotted. ), And in particular, when an inorganic light diffusing agent is added, the inorganic light diffusing agent is hardly evenly dispersed in the transparent thermoplastic resin used as the matrix, and the light efficiency is also significantly decreased.

In addition, according to the hardness of the inorganic light diffusing agent, the production equipment may be worn and damaged, there was a problem that a defect such as a die-line (die-line) occurs in the final light diffusing plate.

In addition, Japanese Laid-Open Publication No. 2003-268022 discloses a methacryl resin composition characterized by adding a light diffusing agent and a non-halogen phosphate ester to a monomer mainly composed of methyl methacrylate. However, the methyl methacrylate resin cannot overcome sagging in the evaluation of heat deflection caused by heat generated in a large-sized TV, and the optical property deterioration due to the addition of phosphate ester is inevitably used for the light diffusion plate. There are a number of problems with this.

SUMMARY OF THE INVENTION The present invention has been made in the form of a multi-layered light diffusing plate for a liquid crystal display device backlight unit by providing a high transparency, light uniformity and excellent brightness and excellent visibility and heat resistance of the liquid crystal display device The present invention provides a structure for a light diffusion plate for a backlight unit.

Another technical problem to be achieved by the present invention is to provide a composition of a specific material for manufacturing the light diffusion plate as described above.

Technical problems to be achieved by the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the following description.

In order to solve the above technical problem, a light diffusing plate for a liquid crystal display device backlight unit having excellent optical properties and heat resistance having a surface shape having a light scattering function according to an embodiment of the present invention is a methacrylic acid-styrene copolymer; 0.1 to 10 parts by weight of a siloxane light diffusing agent having an average particle diameter of 1 to 20 µm and an acrylic type having an average particle diameter of 1 to 20 µm with respect to 100 parts by weight of the base resin mixed with the methyl methacrylate styrene copolymer A base layer comprising 0.1 to 10 parts by weight of a light diffusing agent; A lower coating layer laminated on a surface on which light of the base layer is incident, made of methyl methacrylate-styrene copolymer resin, and having a diffuse reflection pattern formed on a surface thereof; And an upper coating layer laminated on a surface on which light of the base layer is incident, made of methyl methacrylate-styrene copolymer resin, and having a reverse lenticular pattern formed on a surface thereof.

Specific details of other embodiments are included in the detailed description and the accompanying drawings.

Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms, only the present embodiments to make the disclosure of the present invention complete, and common knowledge in the art to which the present invention pertains. It is provided to fully inform the person having the scope of the invention, which is defined only by the scope of the claims. Like reference numerals refer to like elements throughout.

In addition, in the drawings, the size and thickness of layers and films or regions are exaggerated for clarity of description, and when any film or layer is described as being formed "on" of another film or layer, It may be directly on top of the other film or layer, and a third other film or layer may be interposed therebetween.

2 is a cross-sectional view illustrating a light diffusing plate for a backlight unit of a liquid crystal display according to an exemplary embodiment of the present invention, and FIG. 3 is a perspective view illustrating a light diffusing plate for a backlight unit of a liquid crystal display according to an exemplary embodiment of the present invention.

As shown in FIGS. 2 and 3, the light diffusion plates 20 and 21 for the backlight unit of the liquid crystal display according to the exemplary embodiment of the present invention may include a base layer 200, an upper coating layer 210, and a lower coating layer ( 220).

However, if the base layer 200 and the coating layers 210 and 220 each include at least one or more layers, the same or similar effects as those of the present invention may be obtained.

The base layer 200 serves as a support layer when the light diffusion plates 20 and 21 according to the exemplary embodiment of the present invention are applied to the backlight unit. The methacrylic acid-styrene copolymer and the methyl methacrylate methyl-styrene copolymer The mixed resin is used as a matrix, and the light diffusing agent and the light stabilizer are dispersed throughout. And, the thickness of the base layer 200 is preferably in the range of 100 ~ 10,000㎛.

Methacrylic acid-styrene copolymer of the present invention has a composition range consisting of 2 to 20 parts by weight of methacrylic acid units, 80 to 98 parts by weight of styrene units, preferably 5 to 10 parts by weight of methacrylic acid units, styrene units It consists of 90-95 weight part. In addition, the weight average molecular weight of the methacrylic acid-styrene copolymer has a value of 200,000 to 350,000 when converted based on polystyrene.

If the methacrylic acid unit is less than 2 parts by weight, there is a problem that the heat resistance is insufficient, on the contrary, when the methacrylic acid unit is more than 20 parts by weight, the compatibility with the methyl-styrene copolymer is poor, cross-molecular crosslinking Is likely to occur, resulting in a loss of transparency.

Methyl methacrylate-styrene copolymer of the present invention has a composition range consisting of 6 to 94 parts by weight of methyl methacrylate units and 6 to 94 parts by weight of styrene units, preferably 20 to 80 parts by weight of methyl methacrylate units , 20 to 80 parts by weight of styrene units. In addition, the weight average molecular weight of the methyl methacrylate-styrene copolymer has a value of 70,000 to 300,000 when converted based on polystyrene.

If the methyl methacrylate unit is less than 6 parts by weight, there is a problem of insufficient strength. If the methyl methacrylate unit is more than 94 parts by weight, the compatibility with the methacrylic acid-styrene copolymer is poor, resulting in intermolecular Crosslinking tends to occur, resulting in the loss of transparency.

The methacrylic acid-styrene copolymer and the methacrylic acid methyl-styrene copolymer used as the base resin of the base layer 200 can be prepared by known techniques such as emulsion polymerization, suspension polymerization, solution polymerization, and bulk polymerization.

The base layer 200 includes a siloxane light diffusing agent and an acrylic light diffusing agent, each having an average particle diameter of 1 to 20 µm, each of which is 0.1 to 10 parts by weight of 100 parts by weight of the base layer base resin. Parts by weight is added.

The siloxane-based light diffusing agent is a siloxane-based crosslinking particle, and includes both silicone rubber having a low crosslinking density and flexibility as a silicone-based resin particle solid at room temperature, and a silicone resin having a high crosslinking density and a hard silicone resin.

Specific examples of the siloxane light diffusing agent include polydialkyl siloxane resins such as polydimethyl siloxane and polydiethyl siloxane, and silicone resins having a three-dimensional network structure such as siloxane having an epoxy in the terminal group.

Since the siloxane-based crosslinked particles have excellent weather resistance, yellowing does not occur in which the exposed part turns yellow even when the final resin composition is exposed to light for a long time.

In addition, the siloxane-based light diffusing agent has a refractive index of about 1.40 ~ 1.43 lower than other organic cross-linking particles have the advantage that the light diffusion and light transmittance equivalent to that of other light diffusing agents can be obtained even if only a small amount is added.

The siloxane light diffusing agent used in the present invention is spherical crosslinked fine particles having an average particle diameter of 1 to 20 µm, and 0.1 to 10 parts by weight of the base resin 200 used as the base resin is used based on 100 parts by weight of the base resin. desirable. If the average particle diameter of the siloxane light diffusing agent is 1 μm or less, the concealability of the light source is lowered. On the contrary, if the average particle diameter of the siloxane light diffusing agent is 20 μm or more, an excess light diffusing agent is used to secure light diffusivity. This is because a problem that needs to be added occurs.

In addition, when the amount of the siloxane-based light diffusing agent is 0.1 parts by weight or less, when the base layer 200 is finally made, the light diffusion property of the base layer 200 is not good, so that a light source of the backlight unit, that is, a lamp is visible. It is difficult to expect sufficient diffusion of light or light. On the contrary, if the amount of the siloxane-based light diffusing agent is 10 parts by weight or more, the light transmittance is too low, resulting in a problem of reducing the luminance.

The acrylic light diffusing agent is an acrylic spherical crosslinked particle having a refractive index of about 1.46 to 1.56, and is an acrylic monofunctional monomer such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, and methacrylic. Methacrylic acid esters such as phenyl acid and benzyl methacrylate; Acrylic esters, such as methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, phenyl acrylate, and benzyl acrylate, etc. are mentioned, Two or more types can also be used as needed.

It is preferable that the average particle diameter of the organic spherical crosslinked particles used in the present invention is 1 to 20 µm. The reason is that the average particle diameter is 1 µm or less, so that concealability is lowered and the average particle diameter is 20 µm or more. This is because it is necessary to add an excess light diffusing agent to secure the properties.

In addition, the addition amount of the acrylic light diffusing agent is preferably added 0.1 to 10 parts by weight based on 100 parts by weight of the resin of the base layer 200, the reason is that when the base layer 200 is finally made This is because a sufficient light diffusion effect cannot be obtained, and when it is 10 parts by weight or more, the concealment force increases greatly, and a phenomenon in which the light transmittance rapidly decreases occurs.

The base layer 200 of the light diffusion plates 20 and 21 according to the embodiment of the present invention may further include an impact modifier in addition to the basic resin and the light diffusion agent described above.

The impact modifier preferably includes rubber components such as acrylic rubber, butadiene rubber, and the like, but is not limited thereto.

When the rubber component is copolymerized with the methacryl resin, the rubber component has great impact resistance and bending elastic modulus, thereby improving physical properties of the copolymerized methacrylic resin.

As shown in FIG. 2 and FIG. 3, the lower coating layer 220 is stacked on the lower surface of the substrate layer 200 to which light is incident, and the upper coating layer 210 is a substrate layer 200 to which light is emitted. It is laminated on the upper surface of the).

The lower coating layer 220 and the upper coating layer 210 are made by adding an ultraviolet absorber and an antistatic agent to the methyl methacrylate styrene copolymer used for the base resin, and only the light stabilizer without adding the light diffusing agent. It is made by addition.

The upper coating layer 210 and the lower coating layer 220 of the present invention is applied to the light emitting surface and the incident surface of the base layer 200, respectively, the thickness of which depends on the application or required properties Although it does not need to specifically limit as it changes, It is preferable to laminate | stack in the thickness of 10-1000 micrometers, and it is more preferable to laminate | stack in the thickness of 10-100 micrometers.

The antistatic agent removes the space charge generated in the coating layers 210 and 220 to prevent the coating layers 210 and 220 from being charged, and the methyl methacrylate-styrene copolymer resin is also unique in its surface. Since the resistance is high and easy to be charged to the static electricity, this is used to prevent the dust and the like attached to deteriorate the aesthetics of the light diffusion plate, the lighting efficiency is lowered and eventually change the color of the lamp.

The antistatic agent is added in an amount of 0.001 to 10 parts by weight, preferably 0.005 to 5 parts by weight, based on 100 parts by weight of methyl methacrylate resin used as the base resin in the preparation of the coating layers 210 and 220.

Specifically used antistatic agents include at least one of etherimideamide, polyetherester, polyetheresteramide, polyalkylene glycol, dodecyl benzenesulfonic acid alkali metal, tertiary amine, quaternary ammonium, salt, alkyl amine type Is used.

UV absorbers are used to block ultraviolet rays generated from the light source. Any UV absorber that can absorb wavelengths in the range of 250 to 800 nm can be used. Especially, the maximum absorption wavelength is in the range of 250 to 320 nm. It is preferable because the light resistance of the diffusion plate can be improved and coloring of the diffusion plate due to ultraviolet absorption can be suppressed. Specifically, one containing at least one of a benzophenone-based, benzotriazole-based, cyanoacrylate-based, sarichyreto-based, and nickel complex salt-based ultraviolet absorbers may be used.

Specifically, the absorbent preferably contains 0.01 to 2 parts by weight based on 100 parts by weight of methyl methacrylate styrene resin.

The light diffusing plates 20 and 21 according to the embodiment of the present invention may further include an additive within a range that does not affect the intrinsic properties of the light diffusing plates, which are caused by yellowing due to deterioration of the resin. Including additives including any one or more of a blowing agent, other plasticizers, antioxidants, heat stabilizers, lubricants, flame retardants, fillers, mold release agents, dyes, pigments, fungicides, anti-drip agents and nucleating agents added to prevent the appearance defects It may be.

The lower coating layer 220 is laminated on the light incident surface of the base layer 200 through which light is incident from the light source 230, and diffuses the incident light onto the surface of the lower coating layer 220 to A diffuse reflection pattern 222 is formed to promote diffusion.

The diffuse reflection pattern 222 is formed in such a manner that a predetermined patterning is performed on the lower coating layer 220 formed through a separate member. The diffuse reflection pattern 222 is in the form of irregularities that do not have a constant shape for efficient diffusion of light, and is preferably formed entirely on the light incident surface of the lower coating layer 220, and the irregularities constituting the diffuse reflection pattern 222 Average roughness is preferably in the range of 0.3 to 2.0 µm.

The upper coating layer 210 is formed on the light exit surface of the base layer 200, and is formed in the form of a separate member physically separated from the base layer 200. The reverse lenticular pattern 212 is formed on the surface of the upper coating layer 210 to promote the diffusion of the emitted light.

The inverted lenticular pattern 212 formed on the surface of the upper coating layer 210 diffuses the light emitted through the base layer 200 as described above to convert the linear light source into a surface light source. Play a role.

The specific pattern of the inverse lenticular pattern 212 is densely arranged without a gap, as shown by the recessed lenticular pattern rather than the protrusion. When the pitch w of the inverted lenticular pattern 212 is 100 to 300 μm and the height h of the lenticular pattern is 100 to 300 μm, an optical design having a level capable of appropriately controlling a bright line of a lamp is possible. .

The method for producing a laminated light diffuser plate by molding the resin composition according to the present invention may include extrusion molding with a polishing roll, injection molding, vacuum forming, hot press molding, coextrusion molding, and film lamination according to the use of the final multilayer light diffuser plate. Method, solvent adhesion method, polymerization adhesion method, cast polymerization method, surface coating method and the like.

Among them, a multilayer extrusion molding method having a polishing roll is preferred, which is obtained by melting and kneading a resin composition for forming the base layer 200 and a resin composition for forming the application layers 210 and 220 in two or three extruders. Then, it is a method of manufacturing the multilayer light-diffusion plate laminated | stacked in three layers by supplying each to a feed block die or a multi manifold die, and laminating | stacking.

The process of manufacturing the light-diffusion plate of the present invention by a multilayer extrusion molding method having a polishing roll is briefly described as follows.

Polishing rolls to be used for the high-brightness light diffusion plate are formed to form a diffuse reflection pattern 222 and an inverted lenticular pattern 212 in the lower coating layer 220 and the upper coating layer 210 of the light diffusion plate, respectively. I need a roll. The pattern of the polishing roll which will be in contact with the lower coating layer 220 uniformly scatters the light scattered from the various lamps mounted on the backlight, and prevents the lamp line from being visible due to the scattered light. In order to have, the average roughness has a random diffuse reflection pattern 222 within 0.3 to 2 μm.

In addition, the polishing roll pattern, which will be in contact with the top coating layer 210 surface, processes the reverse lenticular pattern 212. When the light scattered by the diffuse reflection pattern 222 formed on the surface of the lower coating layer 220 without the diffusing agent passes through the resin composition of the base layer 200 having the diffusing agent, the light may scatter again. Inverted lenticular pattern 212 to be provided. Therefore, the scattering characteristics of the light can be controlled by the patterns 212 and 222 described above.

The pitch interval of the reverse lenticular pattern 212 is preferably 10 to 500 μm, and the height of the reverse lenticular pattern 212 is preferably 10 to 500 μm. These pitch spacing and height levels are variable depending on the lamp spacing of the backlight, the distance between the diffuser and the lamp, and the brightness of the lamp, and may vary depending on the situation.

The final multilayer light diffusing plate manufactured according to the present invention has a light diffusing property and a light transmittance in the substrate layer 200 in which a methacrylic acid-styrene copolymer and a methyl methacrylate copolymer are mixed to improve heat resistance and optical properties. This excellent spherical siloxane light diffusing agent and acrylic diffusing agent are added. An upper coating layer 210 and a lower coating layer 220 are stacked on the upper and lower surfaces of the base layer 200, respectively.

The coating layers 210 and 220 form a predetermined surface pattern without adding a light diffusing agent, and a light stabilizer and an antistatic agent are added to suppress diffusion plate deformation and brightness by heat generated from a plurality of lamps, and to improve brightness. It effectively copes with yellowing caused by overheating and prevents dust from adhering to static electricity, resulting in excellent display quality of LCD TVs.

 Although the embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to the above embodiments and can be manufactured in various forms, and a person of ordinary skill in the art to which the present invention belongs. It will be appreciated that the present invention may be embodied in other specific forms without changing the technical spirit or essential features of the present invention. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive.

Furthermore, since the amount of the light diffusing agent can be drastically reduced than the conventional light diffusing plate, the wear and tear of the multi-layer light diffusing plate manufacturing equipment is reduced and the light diffusing agent is evenly dispersed to prevent aggregation between the particles and the surface layer. Only antistatic agents and light stabilizers can be used to reduce manufacturing process costs.

Hereinafter, specific embodiments of the present invention will be described.

<Example 1>

① production of the base layer 200;

2 parts by weight of silicon-based particles (GE Toshiba Silicone Co., Ltd.) having an average particle diameter of 2 µm and 100 parts by weight of a resin in which a methacrylic acid-styrene copolymer and a methyl methacrylate methyl-styrene copolymer are mixed, and an acrylic type having an average particle diameter of 8 µm. It was prepared by adding 2 parts by weight of crosslinked particles (Sekisui, Inc.).

② production of coating layer 210;

1 part by weight of an antistatic agent and a light stabilizer were added to 100 parts by weight of the resin in which the methyl methacrylate-styrene copolymer was mixed.

③ Fabrication of multilayer light diffuser plate

   In order to laminate the application layer made of the second resin composition on both sides of the base material layer made of the first resin composition, the prepared first resin composition and the second resin composition were introduced into each extruder, melted and kneaded, 3 layers of 100 µm / 1800 µm / 100 µm by feeding to a feed block die by forming a reverse lenticular having a pitch of 300 µm and a height of 150 µm on the upper surface and a diffuse reflection pattern having an average roughness of 0.8 µm on the lower surface by a polishing roll. The structural multilayer diffuser plate was molded.

<Example 2>

In the same manner as in Example 1, a three-layered multilayer diffusion plate of 300 µm / 1400 µm / 300 µm was formed.

<Example 3>

In the same manner as in Example 1, a three-layered multilayer diffusion plate of 500 µm / 1000 µm / 500 µm was formed.

Comparative Example 1

Styrene-based resin (PS JAPAN Co., Ltd.) as a resin used to manufacture the coating layer 210 was not patterned on the upper and lower surfaces, except that the above was carried out in the same manner as in Example 1. .

Comparative Example 2

Methyl methacrylate-based resin (Mitsubishi Rayon, Inc.) was not used to form the upper and lower surfaces of the base layer 200 resin, except for the above.

Comparative Example 3

Styrene-based resin (PS JAPAN Co., Ltd.) for the base layer 200 resin was not patterned on the upper and lower surfaces, except that the above was carried out in the same manner as in Example 1.

Table 1 shows quantitative tables of Example 1 and Comparative Examples 1, 2, and 3 above.

However, in Table 1, a ₁ : base material layer resin, a ₂ : silicon light diffusing agent / acrylic light diffusing agent, a ₃ : thickness of the base material layer, b ₁ : coating layer resin, b ₂ : antistatic agent / light stabilizer, b _3: the coating layer dugye, c _1: the inverse lenticular pitch, c _2: height of the inverse lenticular, d _1: shows the average roughness of the irregular reflection pattern, respectively.

The physical properties of the specimens prepared as described above were evaluated in the following manner, and the measurement results are shown in Tables 2 and 3.

(1) Sag TEST: One side of the sample cut to 150 mm x 30 mm x 2 mm was fixed, and the amount of warpage was measured after standing in an oven at 110 ° C for 1 hour.

(2) Light resistance: After irradiating ultraviolet rays for 72 hours at a temperature of 60 ℃ using ATLAS-UVCON, the amount of YI (Yellow Index) change was measured.

(3) Light transmittance and light scattering property: The light transmittance and light scattering property of the multilayer board were measured by the haze meter (NDH 5000W, Nippon Denshi Kogaku Kogyo Co., Ltd.).

(4) Luminance: A diffuser plate was mounted on a 32-inch backlight and measured using a BM-7 luminance meter.

(5) Visibility: A diffuser plate was mounted on a 32-inch backlight, and the cold cathode fluorescent lamp concealment was visually observed to evaluate the cold cathode fluorescent lamp with good visibility and poor quality.

Table 2 shows the Sag TEST results.

Table 3 shows the test results of light resistance, optical properties and visibility.

From the results of Table 2, by using a resin in which the methacrylic acid-styrene copolymer and the methyl methacrylate methyl-styrene copolymer are mixed, the thickness of the coating layer is changed by imparting a reverse lenticular pattern on the upper side and a diffuse reflection pattern on the lower side. The light diffusing plates of Examples 1 to 3 molded by the method were less deformed with respect to heat, and from the results of Table 3 above, a resin in which a methacrylic acid-styrene copolymer and a methyl methacrylate methyl-styrene copolymer was mixed was used. As shown in Examples 1 to 3 in which the diffuse lenticular pattern and the diffuse reflection pattern were applied to the lower surface and the thickness of the coating layer without using the light diffusing agent was changed to change the amount of the light diffusing agent, It can be seen that the excellent diffusivity is shown by the surface diffusion function, but the optical property is improved while the optical property is improved and the light resistance is maintained.

The light diffusion plates 20 and 21 manufactured according to the present invention may be used in the backlight unit of the liquid crystal display device, and the liquid crystal display device may be manufactured using the backlight unit.

Although the embodiments of the present invention have been described above with reference to the accompanying drawings, the present invention is not limited to the above embodiments and can be manufactured in various forms, and a person of ordinary skill in the art to which the present invention belongs. It will be appreciated that the present invention may be embodied in other specific forms without changing the technical spirit or essential features of the present invention. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive.

According to the light diffusing plate for the backlight unit of the liquid crystal display according to the embodiment of the present invention, one or more of the following effects exist.

First, by forming a pattern on the surface to improve the light scattering effect, it is possible to manufacture a multi-layer light diffusing plate excellent in light diffusion.

Second, since there is a method of promoting diffusion of light by adding a conventional light diffusing agent and a method of diffusing by a pattern, even if the amount of addition of the light diffusing agent is reduced than in the conventional case, uniform surface light can be obtained, thereby increasing the luminance. It can bring about and reduce the manufacturing cost drastically.

Third, by using a resin in which a methacrylic acid-styrene copolymer and a methyl methacrylate methyl-styrene copolymer are mixed, it is possible to manufacture a light diffusion plate having excellent heat resistance and light diffusivity.

Fourth, it is excellent in light resistance by manufacturing a light diffusion plate in a multilayer structure instead of a single layer structure.

Fifth, since the organic light diffusing agent is used instead of the conventional inorganic light diffusing agent and the amount of the light diffusing agent can be reduced, the light diffusing plate manufacturing equipment has the effect of reducing wear and damage.

Claims (19)

0.1 to 10 parts by weight of a siloxane light diffusing agent having an average particle diameter of 1 to 20 µm with respect to 100 parts by weight of the base resin mixed with the methacrylic acid-styrene copolymer and the methyl methacrylate methyl-styrene copolymer, and 1 to A base layer comprising 0.1 to 10 parts by weight of an acrylic light diffusing agent having an average particle diameter of 20 μm; A lower coating layer laminated on a surface on which light of the base layer is incident, made of methyl methacrylate-styrene copolymer resin, and having a diffuse reflection pattern formed on a surface thereof; And an upper coating layer laminated on a surface on which the light of the base layer is emitted, made of methyl methacrylate-styrene copolymer resin, and having a reverse lenticular pattern formed on a surface thereof. Diffuser plate. The method of claim 1, The lower coating layer and the upper coating layer further comprises 0.01 to 2 parts by weight of an ultraviolet absorber and 0.001 to 10 parts by weight of an antistatic agent based on 100 parts by weight of the methyl methacrylate-styrene copolymer resin. Light diffuser plate for the unit. The method of claim 1, The methacrylic acid-styrene copolymer, 5 to 10 parts by weight of methacrylic acid unit, 90 to 95 parts by weight of styrene units, the light diffusion plate for a backlight unit of the liquid crystal display device. The method of claim 1, The methyl methacrylate-styrene copolymer is 20 to 80 parts by weight of methyl methacrylate units, 20 to 80 parts by weight of styrene units, the light diffusion plate for a backlight unit of the liquid crystal display device. The method of claim 1, The diffuse reflection pattern is a light diffusing plate for a backlight unit of the liquid crystal display device, characterized in that the amorphous pattern having an average roughness of 0.3 ~ 2.0㎛. The method of claim 1, The reverse lenticular pattern is a light diffusion plate for a backlight unit, characterized in that the pitch is in the range of 10 ~ 500㎛, the height is 10 ~ 500㎛ range. The method of claim 1, The siloxane-based light diffusing agent is a silicone resin having a three-dimensional network structure such as polydimethyl siloxane, polydialkyl siloxane resin such as polydiethyl siloxane, siloxane having epoxy at the end group, and the like. Light diffuser plate for the unit. The method of claim 1, The acrylic light diffusing agent is an acrylic monofunctional monomer, methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate and benzyl methacrylate; A light diffusion plate for a backlight unit of a liquid crystal display device comprising at least one selected from acrylic esters such as methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, phenyl acrylate, and benzyl acrylate. The method of claim 1, The substrate layer further comprises an impact modifier including a rubber component selected from acrylic rubber and butadiene rubber, the light diffusion plate for a backlight unit of a liquid crystal display device. The method of claim 1, The lower coating layer and the upper coating layer is a light diffusion plate for a backlight unit of the liquid crystal display device further comprises a UV absorber capable of absorbing ultraviolet rays in the wavelength range of 250 ~ 800nm. The method of claim 10, The ultraviolet absorber is a light diffusion plate for a backlight unit of the liquid crystal display device, characterized in that it comprises at least one of benzophenone-based, benzotriazole-based, cyanoacrylate-based, sarichireto-based, nickel complex salt-based ultraviolet absorber. The method of claim 1, The lower coating layer and the upper coating layer further comprises at least one light stabilizer selected from benzotriazole-based, hindered amine-based, benzophenone-based, silaic acid ester-based light diffusion plate for the backlight unit of the liquid crystal display device . The method of claim 1, The upper coating layer and the lower coating layer are selected from polyetherimideamide, polyetherester, polyetheresteramide, polyalkylene glycol, dodecyl benzenesulfonic acid alkali metal, tertiary amine, quaternary ammonium, salt, alkyl amine system Light diffusion plate for a backlight unit of the liquid crystal display device, characterized in that it further comprises at least one antistatic agent. The method of claim 1, The base layer, the lower coating layer and the upper coating layer are each formed by one method selected from injection molding, extrusion molding, vacuum molding, hot press molding, coextrusion molding, film lamination, solvent bonding, and surface coating. A light diffusion plate for a backlight unit of a liquid crystal display device, characterized in that the adhesive or adhesive bonding to each other. The method of claim 1, The thickness of the base layer is a light diffusion plate for a backlight unit of the liquid crystal display device, characterized in that 100 ~ 10000㎛. The method of claim 1, The thickness of the upper coating layer and the lower coating layer is a light diffusion plate for a backlight unit of the liquid crystal display device, characterized in that each 10 ~ 1000㎛. The method of claim 1, The lower coating layer and the upper coating layer further comprises one or more additives of blowing agent, plasticizer, antioxidant, heat stabilizer, lubricant, flame retardant, filler, mold release material, dye, pigment, antibacterial material, anti-dropping material, nuclear material A light diffusion plate for a backlight unit of a liquid crystal display device. A backlight unit of a liquid crystal display device comprising the light diffusion plate of any one of claims 1 to 17. A liquid crystal display device comprising the backlight unit of claim 18.

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