KR20130012378A - Composition for light diffusion layer, prism sheet including light diffusion layer manufactured by the same, backlight unit and liquid crystal display device - Google Patents

Abstract

PURPOSE: A composition for forming a light-diffusion layer is provided to improve luminance and to reduce intensity loss while uniformly diffusing light emitted from a light discharged from a light-guide plate and diffusion plate. CONSTITUTION: A composition for forming a light-diffusion layer comprises a transparent resin(A) and at least two kinds of transparent particles(B) which have mutually different particle diameters. The particle diameter difference between the two kinds is 2-10 um. A reflectivity difference between the two kinds is 0.05-0.17. A prism sheet comprises a transparent substrate and the light-diffusion layer formed on the back side of the transparent substrate. The light-diffusion layer has an uneven surface with a surface roughness(Ra) of 0.01-0.11 um.

Description

Composition for light diffusing layer, prism sheet, backlight unit and liquid crystal display device including light diffusing layer formed using the same {Composition for Light Diffusion Layer, Prism Sheet Including Light Diffusion Layer Manufactured by the same, Backlight Unit and Liquid Crystal Display Device}

The present invention relates to a resin composition for forming a light diffusion layer, a prism sheet including a light diffusion layer formed using the same, a backlight unit, and a liquid crystal display device.

The backlight unit is disposed behind the liquid crystal display (LCD), and a light source such as a cathode ray lamp (CCFL) or a light emitting diode (LED) is commonly used. Since each light source is a linear light source or a point light source, a diffusion plate, a diffusion sheet, or the like, which can be changed to a surface light source, is used, which causes a lot of light loss. A prism sheet is used for the purpose of compensating for such light loss and improving luminance.

In particular, in order to further improve the brightness of the backlight unit, the light diffusion layer on the back surface of the prism sheet is formed. A general light diffusing layer formed on the back surface of a conventional prism sheet forms irregularities having a predetermined roughness on a surface thereof. Light incident on the back surface of the prism sheet has a transmittance of light incident on the back roughness of the prism sheet, that is, the surface roughness of the light diffusion layer.

However, as the surface of the light diffusing layer becomes rougher, the amount of light that is incident on the rear surface of the prism sheet is scattered or reflected, and thus the amount of light that can be relatively transmitted is reduced. For this reason, if the surface of the light diffusion layer is too rough, there is a disadvantage that the effect of increasing the brightness is inhibited. In addition, when the surface roughness of the light diffusion layer formed on the back surface of the prism sheet is formed by particles, there is a problem that damage to the product may occur due to friction between the prism sheets during lamination or transportation of the prism sheets.

Therefore, the present invention uses a small amount of light-transmitting particles when forming the light diffusing layer on the back of the prism sheet while using the haze inside the light diffusing layer to uniformly diffuse the light emitted from the light guide plate and the diffuser plate, and improve the luminance. It is an object of the present invention to provide a composition for forming a light diffusing layer which can reduce losses, and in particular, prevents damage to the prism sheet due to surface irregularities.

In addition, the present invention can not only improve the brightness while evenly spreading the light emitted from the light guide plate and the diffuser plate, it can reduce the loss of light amount, in particular includes a light diffusion layer on the back to prevent damage during storage and transportation Another object is to provide a prism sheet.

In addition, another object of the present invention is to provide a backlight unit and a liquid crystal display device which not only can improve brightness while uniformly spreading the light emitted from the light guide plate and the diffusion plate, but also can reduce the amount of light.

In order to achieve the above object, the present invention comprises a light-transmitting resin (A) and at least two types of light-transmitting particles (B) having a different average particle diameter, the difference in the average particle diameter of at least two of the light-transmitting particles Provided is a composition for forming the light diffusion layer on the back of the prism sheet, characterized in that 2 to 10um, the difference in refractive index of at least two species is 0.05 to 0.17.

Preferably, the composition for forming a light diffusion layer on the back of the prism sheet further includes a photoinitiator (C) and a solvent (D), and the light transmitting particles include first light transmitting particles and second light transmitting particles having different average particle diameters. It is good to be done.

The average particle diameter of the light transmitting particles is preferably 0.1 μm to 11 μm, and the first light transmitting particles and the second light transmitting particles may be mixed and used in a weight ratio of 3: 7 to 7: 3.

The light transmitting particles may be included in an amount of 0.5 to 20 parts by weight based on 100 parts by weight of the total light diffusing coating composition.

In order to achieve another object of the present invention, the present invention, a prism sheet comprising a transparent substrate and a light diffusing layer formed on the rear surface of the transparent substrate using the composition for forming a light diffusing layer according to the present invention described above. To provide.

The light diffusion layer preferably has surface irregularities having a surface roughness Ra value of 0.05 to 0.11 μm.

The prism sheet preferably has an internal haze of 5 to 20 and an external haze value of 0.05 to 3 due to surface irregularities.

In order to achieve another object of the present invention, the present invention provides a backlight unit comprising the prism sheet.

In order to achieve another object of the present invention, the present invention provides a liquid crystal display device comprising the prism sheet.

The composition for forming a light diffusion layer according to the present invention includes at least two kinds of light-transmitting particles having different average particle diameters when applied to the back of the prism sheet, thereby expressing the difference in the size and refractive index of the light-transmitting particles while using a small amount of light-transmitting particles. By implementing light diffusion using internal haze, which may be possible, not only the light emitted from the light guide plate and the diffusion plate may be evenly distributed, but also the luminance may be reduced and the amount of light may be reduced. In particular, the prism sheet including the light diffusing layer formed by using the light diffusing layer forming composition has a low surface roughness Ra value, thereby preventing the diffusion of the diffuser plate or the light guide plate located on the lower surface of the prism sheet, as well as storing or transporting the prism sheet. It is possible to prevent the occurrence of defects caused by the prism of the prism sheet that may occur during the. Therefore, the prism sheet may be usefully used for the backlight unit and the liquid crystal display.

Hereinafter, the present invention will be described in more detail.

Light diffusion layer  Formation composition

The composition for forming a light-diffusion layer on the back of the prism sheet according to the present invention (hereinafter also referred to simply as "composition for forming a photo-acid layer") comprises at least two kinds of light-transmitting particles (B) having a different average particle diameter from the light-transmissive resin (A). It is made to include, may further comprise a photoinitiator (C) and a solvent (D). The detailed description of each component is as follows.

Translucency  Resin (A)

The light-transmissive resin can be used without limitation so long as it can cause a crosslinking reaction or a polymerization reaction.

Preferably, the light transmissive resin may use a photocurable resin, and the photocurable resin may include a photocurable polyfunctional monomer.

It is preferable that the functional group of the said photocurable polyfunctional monomer is light, an electron beam, and radiation polymerization property, and a photopolymerizable functional group is especially preferable. As said photopolymerizable functional group, unsaturated polymerizable functional groups, such as a (meth) acryloyl group, a vinyl group, a styryl group, and an allyl group, etc. are mentioned, Especially, a (meth) acryloyl group is preferable.

Specific examples of the photocurable polyfunctional monomer include (meth) acrylic acid diesters of alkylene glycols such as neopentyl glycol acrylate, 1,6-hexanediol (meth) acrylate, and propylene glycol di (meth) acrylate; Polyoxyalkylene glycol (meth) acrylic acid di, such as triethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, and polypropylene glycol di (meth) acrylate Esters; (Meth) acrylic acid diesters of polyhydric alcohols such as pentaerythritol di (meth) acrylate; Ethylene oxides such as 2,2-bis {4- (acryloxydiethoxy) phenyl} propane and 2-2-bis {4- (acryloxypolypropoxy) phenyl} propane; Or (meth) acrylic acid diesters of propylene oxide adducts. Moreover, epoxy (meth) acrylates, urethane (meth) acrylates, polyester (meth) acrylates, etc. can also be used for the photocurable polyfunctional monomer which has the said photopolymerizable functional group.

As the photocurable polyfunctional monomer, a polyfunctional monomer having three or more (meth) acryloyl groups in one molecule can be used.

As a specific example of the polyfunctional monomer which has three or more (meth) acryloyl groups in the said molecule | numerator, a trimethylol propane tri (meth) acrylate, a trimethylol ethane tri (meth) acrylate, and 1,2, 4- cyclo Hexanetetra (meth) acrylate, pentaglycerol triacrylate, pentaerythritol tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol triacrylate, dipentaerythritol pentaacrylate, dipentaerythritol tetra (Meth) acrylate, dipentaerythritol hexa (meth) acrylate, tripentaerythritol triacrylate, tripentaerythritol hexatriacrylate, and the like.

The photocurable polyfunctional monomers exemplified above may be used alone or in combination of two or more.

The light-transmissive resin is not particularly limited but is preferably contained in an amount of 10 to 90 parts by weight based on 100 parts by weight of the total composition for forming a light diffusion layer. When the content of the light-transmitting resin is included in the range of 10 to 90 parts by weight based on the above standards it is preferable because it shows excellent light diffusion.

Translucency  Particle (B)

The light-transmitting particles are added to improve light diffusion and brightness. According to the present invention, the light-transmitting particles include at least two species having different average particle diameters and refractive indices. Preferably the difference in the average particle diameter of at least two species of the light transmitting particles is 2 to 10um, the difference in the refractive index of at least two species may be preferably used. More preferably, the translucent particles are composed of first and second translucent particles having different average particle diameters, and the first and second translucent particles have a difference in average particle diameter of 2 to 10 μm and a difference in refractive index. 0.05 to 0.17 is preferred.

As described above, when two kinds of particles having different average particle diameters are used as the light-transmitting particles, particles having a small average particle size are distributed among particles having a large average particle size, so that light passing through particles having a large average particle diameter Transmitting and refraction not only improves the light transmission efficiency, but also improves the light diffusion function and helps to display uniform brightness. In addition, when the refractive indexes of the light-transmitting particles used are different from each other, incident light may cause efficient internal scattering and reflection in the light diffusion layer to help improve luminance.

As the light-transmitting particles described above, those generally used in the art may be used without limitation, however, in selecting and using at least two different types of light-transmitting particles, the difference in average particle size and difference in refractive index satisfy the predetermined conditions described above. If a small amount of light-transmitting particles is used, an excellent brightness enhancement effect can be obtained.

 As the light transmitting particles, particles selected from the group consisting of inorganic materials such as glass, talc, aluminum oxide, titanium dioxide, and organic materials such as polystyrene, polycarbonate, and PMMA may be used. In the above, particles such as talc, aluminum oxide, and titanium dioxide do not transmit light, but have a function of reflecting from the surface to diffuse light. Particles such as glass, polystyrene, polycarbonate, and PMMA transmit light and refract the incoming light. It has the function of diffusing light by changing its path.

It is preferable that the average particle diameter of the said translucent particle is 0.1-11 micrometers. It is effective that the light-transmitting particles have a spherical shape to improve light transmittance and light diffusion efficiency. In this case, when the first light transmitting particles and the second light transmitting particles are used as the light transmitting particles, the difference in the average particle diameter of the first light transmitting particles and the second light transmitting particles is preferably 2 to 10 μm. When the difference between the average particle diameter of the first light-transmitting particle and the second light-transmitting particle is less than 2 μm, it is difficult to exhibit sufficient light diffusion inside the light-transmitting resin layer, and when the thickness is greater than 10 μm, the surface of the light-diffusion layer is roughened and the haze value is greatly increased. There is a disadvantage.

In addition, the light transmitting particles preferably have a refractive index of 1.42 to 1.59. In this case, when the first light transmitting particles and the second light transmitting particles are used as the light transmitting particles, the refractive index difference between the first light transmitting particles and the second light transmitting particles is preferably 0.05 to 0.17. When the difference in refractive index between the first and second transparent particles is less than 0.05, the scattering inside the light diffusing layer is small, so that surface irregularities must be increased in order to obtain sufficient light diffusivity. There is a problem in that damage may occur due to friction between the prism films and friction with the diffusion sheet during backlight assembly. In addition, when the difference between the refractive index of the first transparent particles and the second transparent particles is more than 0.17, the internal scattering is obvious, there is a problem that the haze rise is prominent, and the brightness is lowered.

When the first light transmitting particles and the second light transmitting particles are used as the light transmitting particles, the mixing ratio is preferably used in a weight ratio of 3: 7 to 7: 3. When the mixing ratio of the first light-transmitting particle and the second light-transmitting particle is included in the above range, it is possible to improve brightness by improving the light diffusion function while increasing the light transmittance.

The light-transmitting particles are preferably contained in 0.5 to 20 parts by weight based on 100 parts by weight of the total composition for forming a light diffusion layer. If the content of the light-transmitting particles is less than 0.5 parts by weight based on the above standard, there is a problem in that the light diffusion property is lowered and the brightness enhancement effect is lowered.

Photoinitiator (C)

The photoinitiator can be used without limitation that is generally used in the art.

The photoinitiator may be used at least one selected from the group consisting of benzene ether, benzyl ketal, alpha hydroxyalkyl phenone, amino alkyl phenone, phosphine oxide.

The photoinitiator is more specifically 2-methyl-1- [4- (methylthio) phenyl] 2-morpholinepropanone-1, diphenylketonebenzyldimethylketal, 2-hydroxy-2-methyl-1-phenyl- 1-one, 4-hydroxycyclophenylketone, dimethoxy-2-phenylacetophenone, anthraquinone, fluorene, triphenylamine, carbazole, 3-methylacetophenone, 4-knoloacetophenone, 4,4 -Dimethoxyacetophenone, 4,4-diaminobenzophenone, 1-hydroxycyclohexylphenyl ketone, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, bis (2,9-dimethoxybenzoyl) At least one selected from the group consisting of -2,4,4-trimethylpentylphosphine oxide and bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide can be used.

Preferably, the photoinitiator is a combination of at least one selected from the group consisting of benzene ether, benzyl ketal, alpha hydroxyalkyl phenone and aminoalkyl phenone based initiators with at least one selected from the group consisting of phosphine oxide based initiators. Can be used.

The photoinitiator is preferably included 0.1 to 10 parts by weight based on 100 parts by weight of the total composition for forming a light diffusion layer. When the content of the photoinitiator is less than 0.1 parts by weight based on the above, there is a problem in that the curing speed is slow, and when it exceeds 10 parts by weight, the yellowing phenomenon becomes severe.

Solvent (D)

The solvent can be used without limitation so long as it is known in the art.

Specific examples of the solvent include alcohols (methanol, ethanol, isopropanol, butanol, methylcellulose, ethyl solusorb, etc.), ketones (methyl ethyl ketone, methyl butyl ketone, methyl isobutyl ketone, diethyl ketone, and dipropyl). Ketone, cyclohexanone, etc.), hexane type (hexane, heptane, octane etc.), benzene type (benzene, toluene, xylene etc.) etc. are mentioned. The solvents exemplified above may be used alone or in combination of two or more.

The solvent is not necessarily limited, but the solvent may be included in an amount of 0.1 to 75 parts by weight based on 100 parts by weight of the total composition for forming the light diffusion layer. If the content of the solvent is less than 0.1 parts by weight based on the above standard, the viscosity of the composition is high, the workability is lowered, and if it exceeds 75 parts by weight, it takes a lot of time during the drying and curing process.

The composition for forming the light diffusion layer may further include at least one selected from the group consisting of antioxidants, UV absorbers, light stabilizers, leveling agents, surfactants, and antifouling agents, if necessary, in addition to the above components.

Prism sheet

According to an embodiment of the present invention, there is provided a prism sheet comprising a transparent substrate and a light diffusing layer formed on the rear surface of the transparent substrate by using the light diffusing layer forming composition according to the present invention.

The substrate is not limited, but preferably a water-dispersed polyurethane on a transparent optical polymer such as polyethylene terephthalate (hereinafter referred to as PET) or polycarbonate, or a transparent optical polymer such as polyethylene terephthalate (hereinafter referred to as PET) or polycarbonate Or the film in which the acrylic emulsion coating layer is apply | coated by the primer type of 1 micrometer or less can be used. Although the thickness of the said base material is not restrict | limited, Preferably it is about 1-200 micrometers, More preferably, it may be 20-100 micrometers.

The coating of the composition for forming the light diffusion layer may be applied without limitation to the method generally applied in the art, for example, may be carried out by applying gravure coating, roll coating, knife coating, and the like. The coating thickness of the said light-diffusion layer forming composition is 1-10 micrometers, Preferably it is 2-6 micrometers.

After coating the composition for forming the light diffusion layer is irradiated with UV light to cure the composition for forming the light diffusion layer, the irradiation amount of UV light is about 0.1 ~ 2J / ㎠, preferably 0.2 ~ 0.5J / ㎠ and the wavelength is 365nm It is recommended to use a metal halide lamp having the main wavelength.

The prism sheet is excellent in productivity due to the fast curing speed during manufacturing, and the prism sheet produced after curing has excellent light diffusivity and high brightness, low curl, excellent color change, yellowing resistance and adhesion to the film. Indicates.

At this time, it is preferable that the light-diffusion layer of this invention is surface roughness by surface unevenness, ie, the centerline average roughness Ra of 0.05-0.11. Here, center line average roughness Ra is calculated | required by the method prescribed | regulated by JISB0601. When the center line average roughness value is 0.05 to 0.11, excellent light diffusivity of the backlight unit may be ensured at the same time.

In addition, the light diffusion layer of the present invention preferably has an internal haze value of 5 to 20 due to internal diffusion and an external haze value of surface irregularities of 0.05 to 3. If the internal haze is less than 5, the light diffusivity of the light emitted from the backlight unit is lowered, and if it exceeds 20, the luminance is lowered. In addition, when the external haze is out of the above range, damage may occur due to friction between the prism films when the prism films are laminated or transported, or the friction with the diffusion sheet during backlight assembly.

Backlight Unit and Liquid Crystal Display

According to an embodiment of the present invention, a backlight unit including the prism sheet is provided.

The backlight unit is not limited and may employ a structure known in the art. For example, a light source such as a CCFL, an LED, a light guide plate for guiding light from the light source, a diffusion sheet, a prism sheet, or the like may be provided on the upper surface of the light guide plate.

In addition, according to an embodiment of the present invention provides a liquid crystal display device having the prism sheet. Preferably, the liquid crystal display may include the backlight unit including the prism sheet according to the present invention.

That is, the prism sheet of the present invention can be preferably used in reflective, transmissive, semi-transmissive LCD or LCD of various driving methods such as TN type, STN type, OCB type, HAN type, VA type, and IPS type. In addition, the prism sheet of the present invention can be preferably used for various display devices such as a plasma display, a field emission display, an organic EL display, an inorganic EL display, and an electronic paper.

The present invention will be described in more detail with reference to the following examples. These examples are only for illustrating the present invention, and the scope of the present invention is not limited to these examples.

< Example  1 to 8 and Comparative example  1 to 8

Each component was mixed at a weight ratio as shown in Table 1 and then stirred for 30 minutes with a stirrer to prepare a composition for forming a light diffusion layer.

Weight portion Example Comparative example One 2 3 4 5 6 7 8 One 2 3 4 5 6 7 8 Polyfunctional monomer 45 45 45 45 45 45 45 45 45 45 45 45 45 45 45 45 Photoinitiator (a) 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 2 (b) 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 abandonment
particle (a) 5 5 5 5 5 (b) 5 5 3 7 5 (c) 5 5 5 5 5 5 (d) (e) 5 5 5 5 (f) 5 5 5 (g) 5 (h) 5 weapon
particle (a) 5 7 3 5 5 (b) 5 5 solvent (a) 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8
Dispersant (b) 34 34 34 34 34 34 34 34 34 34 34 34 34 34 34 34 Disper
BYK2008 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 0.3 Leveling agent BYK371 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 Average particle size difference (um) 5 5 7 3 4 5 2 2 2 5 0 0 0 2.95 9 5 Refractive index difference 0.07 0.16 0.16 0.07 0.13 0.10 0.13 0.13 0 0 0.03 0.13 0.16 0 0 0.03

The components used in Table 1 are as follows.

Polyfunctional monomer: pentaerythritol triacrylate (M340, manufactured by Miwon Corporation)

Photoinitiator (a): 1-hydroxycyclohexyl phenyl ketone (I-184, the Shiva Corporation make)

Photoinitiator (b): 2-methyl-1- [4- (methylthio) phenyl] 2-morpholinepropanone-1 (I-907, manufactured by Shiva Corporation)

Organic particle | grains (a): 3 micrometers of average particle diameters, 1.56 polystyrene-polymethyl methacrylate particle | grains (XX-09HW, the Sekisui KK make)

Organic particle | grains (b): 5 micrometers of average particle diameters, 1.56 polystyrene-polymethyl methacrylate particle | grains (XX-05HW, the Sekisui KK make)

Organic particle (c): average particle diameter 3 micrometers, refractive index 1.59 polystyrene particle (XX-10HW, Sekisui KK make)

Organic particle | grains (d): Average particle diameter 5 micrometers refractive index 1.49 polymethylmethacrylate particle (MBX-5, the Sekisui KK make)

Organic particle (e): average particle diameter 8 micrometer refractive index 1.59 polystyrene particle (SBX-8, the Sekisui company make)

Organic particle | grains (f): average particle diameter 8 micrometer refractive index 1.49 polymethylmethacrylate particle (MBX-8, the Sekisui company make)

Organic particles (g): average particle diameter 50 nm refractive index 1.59 polyester particles (Soken)

Organic particle (h): average particle diameter 12um refractive index 1.59 polystyrene particles (SBX-12, Sekisui Co., Ltd.)

Inorganic particles (a): average particle diameter 3㎛ spherical refractive index 1.43 silicon particles (Tospearl145, Momentive)

Inorganic particles (b): average particle diameter 1㎛ spherical refractive index 1.43 silicon particles (Tospearl120, Momentive)

Solvent (a): cyclohexanone (made by Aldrich)

Solvent (b): toluene (made by Aldrich)

< Experimental Example >

The composition for forming a light diffusion layer prepared in Examples and Comparative Examples was applied to a 188 μm-thick polyethylene terephthalate transparent substrate using a gravure coater, dried at 80 ° C. for 1 minute, and cured by ultraviolet irradiation to have a thickness. The prism sheet in which the optical-acid layer of 5 micrometers was formed was manufactured. The physical properties and properties of the thus prepared prism sheet were evaluated as follows, and the results are shown in Table 2 below.

<Hayes>

The external haze and internal haze of the prism sheet prepared in the above experimental example were measured using a spectrophotometer (HZ-1, Suga, Japan).

<Average roughness>

The centerline average roughness (Ra) value was measured in accordance with the method defined by JIS B 0601.

<Surface smoothness>

The coated surface of the prism sheet prepared in the above experimental example was observed in the direction of inclination of 20 to 30 degrees in the light of electric light, and the presence or absence of aggregation (microscopic) of uniformity of the surface layer was confirmed.

A: There is no microscopic agglomeration on the surface layer and it is uniform.

B: Micro-agglomeration appears on the surface layer, but it is very slight.

C: Microscopic aggregation is remarkable in the surface layer.

<Cracking Prism Sheet>

After stacking 20 pieces of the prism sheets prepared in the above experimental example, the tearing phenomenon of the prism sheet was visually observed while removing the sheet in the lower layer part, and evaluated as follows.

◎: No prism in prism sheet

○: Partial cleavage of the prism sheet was observed

×: Mostly the splitting phenomenon of the prism sheet was observed

<Division of Diffusion Plate>

The prism sheet prepared in the above experimental example was mounted on a 42-inch backlight unit (LC420WUF) for a liquid crystal display panel, and fixed to a vibration shocker (WANGSAN ENGINEERING, WSVT-4000), and the vibration was carried out for 10 minutes at 10 Hz and 20 minutes at 60 Hz. Next, the surface of the diffuser plate mounted on the back of the prism sheet was visually observed for delamination and evaluated as follows.

◎: No diffusion plate split phenomenon

○: part of the diffusion plate split phenomenon

×: most of the diffusion plate split phenomenon

Example Comparative example One 2 3 4 5 6 7 8 One 2 3 4 5 6 7 8 External haze 2 3 2 One One 0.5 One 0.6 3 4 5 5 6 3 5 4 Internal haze 12 14 22 15 16 13 18 20 4 8 5 10 12 2 8 12 Ra 0.09 0.16 0.12 0.08 0.1 0.05 0.07 0.05 0.5 0.45 0.28 0.30 0.19 0.17 0.40 0.37 Surface smoothness A A A A A A A A C B B B B B C C Prism Cleft ◎ ○ ◎ ◎ ◎ ◎ ◎ ◎ × × × × × ○ × X Diffuser Plate Splitter ◎ ○ ◎ ◎ ◎ ◎ ◎ ◎ × x ○ ○ ○ ○ × X

As shown in Table 2, in the case of the prism sheet of the embodiment using two sets of light-transmitting particles having a different average particle diameter according to the present invention, the difference in the average particle diameter and the refractive index difference of the light-transmitting particles within the preferred range of the present invention Compared with the prism sheet of the comparative example, it can be seen that the external haze and Ra can be prevented while preventing the splitting of the prism sheet or the splitting of the diffusion plate.

Claims (10)

It comprises a light-transmitting resin (A) and at least two kinds of light-transmitting particles (B) having a different average particle diameter,
The difference in the average particle diameter of at least two species of the translucent particles is 2 to 10um, and the difference in refractive index of at least two species is 0.05 to 0.17, the composition for forming a light diffusion layer on the back of the prism sheet. The method according to claim 1,
The composition for forming a light diffusion layer on the back of the prism sheet further comprises a photoinitiator (C) and a solvent (D),
The light-transmitting particles are made of a first light-transmitting particle and a second light-transmitting particle having a different average particle diameter,
The first light-transmitting particle and the second light-transmitting particle have a difference in average particle diameter of 2 to 10 μm, and a difference in refractive index of at least two species of 0.05 to 0.17. The method according to claim 1,
The light-transmitting particle average particle diameter is 0.1㎛ to 11㎛ composition for forming a light diffusion layer on the back of the prism sheet. The method according to claim 2,
The first light-transmitting particle and the second light-transmitting particle is a composition for forming a light diffusion layer on the back of the prism sheet, characterized in that the mixture is used in a weight ratio of 3: 7 to 7: 3. The method according to claim 1,
The light transmitting layer is a composition for forming a light diffusion layer on the back of the prism sheet, characterized in that it comprises 0.5 to 20 parts by weight based on 100 parts by weight of the total light diffusing coating composition. A prism sheet comprising a transparent substrate and a light diffusion layer formed on the back surface of the transparent substrate using the composition for forming a light diffusion layer according to any one of claims 1 to 5. The method of claim 6,
The light diffusing layer is a prism sheet, characterized in that the surface roughness Ra has a surface roughness of 0.05 to 0.11㎛. The method of claim 6,
The prism sheet has an inner haze of 5 to 20 and an outer haze value of 0.05 to 3. A backlight unit comprising the prism sheet of claim 6. The prism sheet of Claim 6 is included, The liquid crystal display device characterized by the above-mentioned.