KR20080086210A - Heat resistant light diffusion plate - Google Patents

Abstract

A heat resistant multi-layer light diffusion plate is provided to realize high diffusibility, high luminance, low absorptivity and excellent heat resistance, and to obtain an easily handled light diffusion sheet applicable to backlight units for LCDs, lighting devices, signboards or glass showcases. A heat resistant multi-layer light diffusion plate(120) comprises: (A) an intermediate layer(120a) comprising (i) 100 parts by weight of an intermediate layer base resin obtained by copolymerizing 80-99.9 wt% of a styrenic monomer and 0.1-20 wt% of at least one monomer selected from methacrylic acid monomer, maleic anhydride monomer and maleimide monomer, and (ii) 0.05-10 parts by weight of at least one light diffusing agent(120b) selected from acrylic organic particles and silicone-based organic particles; and (B) a surface layer(120c) comprising (i) 100 parts by weight of a surface layer base resin formed of a transparent resin, and (ii) 1-25 parts by weight of a permanent antistatic agent, wherein the surface layer is stacked on either surface of the intermediate layer.

Description

Heat Resistant Multi-layer Diffuser Plate {HEAT RESISTANT LIGHT DIFFUSION PLATE}

1 is a cross-sectional view schematically showing an embodiment of the heat-resistant multilayer light diffusion plate of the present invention.

2 is a schematic cross-sectional view of the backlight unit 100 for a liquid crystal display of the present invention.

* Description of Major Symbols in Drawings *

120 heat-resistant multilayer light diffuser, 120a intermediate layer, 120b light diffuser, 120c surface layer,

100 Backlight Unit, 110 Optical Sheet, 110a Protective Sheet, 110b Prism Sheet, 110c Diffusion Sheet, 130 Light Source, 140 Reflective Sheet, 150 Bottom Chassis

The present invention relates to a heat-resistant multilayer light diffusion plate, and more particularly, by using a heat-resistant light-diffusion resin as an intermediate layer base resin, it has high diffusivity and brightness, and is easy to handle as a light diffusion sheet. The present invention relates to a heat-resistant light diffusion plate having a low water absorption rate, excellent heat resistance, dimensional stability, and mechanical strength, which is suitable for use in a backlight for a liquid crystal display, a lighting device, a signboard, or a glass showcase, and a backlight unit for a liquid crystal display device including the same.

Generally, a light diffusion plate is a sheet for making a point light source or a line light source appear as a uniform surface light source. Such a light diffusion sheet requires high diffusivity in order to make the back light or contents visible from the outside and to display uniform brightness, and at the same time, it is required to realize high luminance of the light exit surface to increase light efficiency (high brightness, low power consumption). do.

In order to be used as a light diffusion plate, in addition to the optical characteristics, it must have thermal and mechanical characteristics that can satisfy the conditions of the surrounding environment. Polymethyl methacrylate has been widely used as an optical material because of its excellent light transmittance and low haze. In particular, in recent years, polymethyl methacrylate has been used as a light diffusion plate material in a backlight of a liquid crystal display. However, polymethyl methacrylate-based resins have high moisture absorption, and thus, when used as a light diffusion plate, warpage of the plate often occurs due to absorption of water, evaporation, and temperature increase by a light source.

As a light diffusion sheet conventionally used, a light diffusion sheet in which silicon particles are dispersed in polymethyl methacrylate, which is a transparent thermoplastic resin disclosed in Japanese Patent Application Laid-Open No. Hei 172801, improves light diffusivity and light transmittance. have. The invention described in the above document increases the light transmittance and diffusivity at the same time using silicon particles, but there is a problem that the mechanical strength and heat resistance due to water absorption of polymethyl methacrylate, which is a base material, are reduced.

In order to solve the problems of the prior art as described above, an object of the present invention is to provide a heat-resistant multi-layer light diffusion plate having a high diffusivity and brightness, low absorption and excellent heat resistance.

Another object of the present invention is to provide a backlight unit for a liquid crystal display device including the heat-resistant multilayer light diffusion plate.

In order to achieve the above object, the present invention (A) iii) 0.1 to 20 monomers selected from the group consisting of 80 to 99.9% by weight of the styrene monomer, methacrylic acid monomer, maleic anhydride monomer and maleimide monomer 100 weight part of intermediate | middle layer base resin copolymerized by weight%, and ii) 0.05-10 weight part of light-diffusion agents chosen from the group which consists of acryl-type organic particle | grains and silicone type organic particle | grains; And (B) a surface layer comprising (i) 100 parts by weight of a surface layer base resin made of a transparent resin, and ii) 1 to 25 parts by weight of a permanent antistatic agent, wherein the surface layer is formed on at least one side of the intermediate layer. It provides a heat-resistant multilayer light diffusion plate characterized in that the laminated.

In addition, the present invention provides a backlight unit for a liquid crystal display device including the heat-resistant multilayer light diffusion plate.

Hereinafter, the present invention will be described in detail.

MEANS TO SOLVE THE PROBLEM As a result of using the resin which copolymerized the styrene-type monomer, 1 or more types selected from the group which consists of a methacrylic acid monomer, a maleic anhydride monomer, and a maleimide type monomer as a light-diffusion plate intermediate layer base resin, heat resistance is remarkably improved, and It was confirmed that the characteristics are excellent, based on this, the present invention was completed.

The intermediate layer resin composition constituting the intermediate layer of the present invention is a copolymer of 80 to 99.9% by weight of styrene monomer and 0.1 to 20% by weight of monomer selected from at least one selected from the group consisting of methacrylic acid monomer, maleic anhydride monomer and maleimide monomer. 100 parts by weight of the interlayer base resin and 0.05 to 10 parts by weight of a light diffusing agent selected from the group consisting of acrylic organic particles and silicon organic particles.

In addition, the intermediate layer base resin may be copolymerized further including 0.1 to 30 parts by weight of methyl methacrylate monomer (based on 100 parts by weight of styrene monomer).

The styrene-based monomers used in the intermediate layer resin of the present invention include styrene, α-methyl styrene, ρ-bromo styrene, ρ-methyl styrene methyl styrene) or p-chloro styrene, and the like, and the maleimide monomer may be maleimide, phenylmaleimide or cyclohexylmaleimide.

The monomer selected from the group consisting of methacrylic acid, maleic anhydride and maleimide monomers used in the intermediate layer base resin of the present invention is preferably included in an amount of 0.1 to 20% by weight, and more preferably polymerized. It is included in the amount of 0.5 to 15% by weight to polymerize. If the content is less than 0.1% by weight does not improve the heat resistance of the copolymer resin, if it exceeds 20% by weight may lower the mechanical properties such as impact strength and problems such as color change of transmitted light.

Methyl methacrylate monomer that can be optionally added to the intermediate layer resin is preferably included within 0.1 to 30 parts by weight based on 100 parts by weight of the styrene-based monomer, when the methacrylate content exceeds 30 parts by weight The problem of increasing the absorbency may occur.

The intermediate layer of the present invention is prepared as a light diffusing agent by mixing one or more kinds of acrylic organic particles or silicon organic particles having different refractive index with the intermediate layer base resin to the intermediate layer base resin.

The acrylic organic particles may be a resin particle obtained by polymerizing an acryl-based monomer alone, a resin particle obtained by polymerizing a monomer having one or more double bonds in a molecule having at least 50% by weight of an acrylic monomer and a radical polymerization, A crosslinked resin particle obtained by polymerizing a monomer having at least 50% by weight or more of an acrylic monomer and a monomer capable of radical polymerization in a molecule, or ㉣ having at least 50% by weight or more of an acrylic monomer or a radical polymerizable double bond in a molecule Crosslinked resin particles obtained by polymerizing monomers and monomers having at least two or more double bonds capable of radical polymerization in a molecule can be used.

Specifically, the acrylic monomers are methyl methacrylic acid, ethyl methacrylic acid, butyl methacrylic acid, cyclohexyl methacrylic acid, phenyl meta Phenyl methacrylic acid, benzyl methacrylic acid, 2-ethylhexyl methacrylic acid, or 2-hydroxyethyl methacrylic acid Ester methacrylic acid; Methyl acrylic acid, ethyl acrylic acid, butyl acrylic acid, cyclohexyl acrylic acid, phenyl acrylic acid, benzyl acrylic acid, 2 -Ester acrylic acid, such as 2-ethylhexyl acrylic acid or 2-hydroxyethyl acrylic acid, etc. can be used individually or in mixture of 2 or more types.

The monomer having one double bond in the molecule capable of radical polymerization is not particularly limited, in particular styrene; α-substituted styrenes such as α-methyl styrene, α-ethyl styrene, or α-chloro styrene; Or styrene such as substituted styrene such as fluoro styrene, chloro styrene, bromo styrene, or chloromethyl styrene, and derivatives thereof.

As the monomer having two double bonds capable of radical polymerization in the molecule, a monomer such as allyl acrylate or allyl methacrylate can be used.

It is preferable that the particle size of the acrylic organic particles as described above is 1 to 20 ㎛, when the particle size is less than 1 ㎛ may cause a problem that the color of the transmitted light changes to a red or yellow system and the diffusion effect is also reduced, 20 ㎛ Even if it exceeds the lack of light diffusion effect may cause a problem to add a large amount of the diffusion agent.

The silicon-based organic particles used as another light diffusing agent in the present invention may be made of a skeleton of difunctional siloxane units or trifunctional siloxane units, and silicon-based organic particles having organic functional groups on the surface thereof may be used.

Specifically, the silicon-based organic particles may be prepared by hydrolyzing and condensing chlorosilanes such as dimethyldichlorosilane, diphenylchlorosilane, phenylmethyldichlorosilane, methyltrichlorosilane, or phenyltrichlorosilane. In addition, the silicon-based organic particles prepared as described above are benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, p-chlorobenzoyl peroxide, dicumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl- Peroxides such as 2,5-di (tert-butylperoxy) hexane and the like may also be used to form the crosslinked polymer. In particular, when the polymer has silanol end groups, it can be condensed and crosslinked with any alkoxysilane.

It is preferable that the crosslinked polymer has 2 to 3 organic groups per silicon atom.

When the silicon-based organic particles include a large number of organic groups or phenyl groups directly connected to silicon atoms, the refractive index of the particles is generally increased. The refractive index of the silicon-based organic particles of the present invention may be appropriately selected according to the composition of the particles. It is preferably about 1.39 to 1.47.

It is preferable that the average particle diameter of the said silicon type organic particle | grains is 1-20 micrometers, More preferably, it is 1-10 micrometers. If the average particle diameter is less than 1 μm, the particle size is smaller than the wavelength of light, so that light is difficult to diffuse. If the average particle diameter is more than 20 μm, light diffusion performance is deteriorated.

The acrylic organic particles or silicon-based organic particles added as the light diffusing agent are preferably included in an amount of 0.05 to 10 parts by weight, and more preferably 0.1 to 8 parts by weight, based on 100 parts by weight of the interlayer base resin. If the content is less than 0.05 parts by weight, sufficient light diffusion effect may not occur. If the content is more than 10 parts by weight, the impact strength of the final heat-resistant light diffusion resin is lowered, and the luminance is lowered when the light diffusion plate is manufactured. There is a problem.

Acrylic organic particles or silicon-based organic particles as described above may be used alone, or may be used by mixing.

In addition to the acrylic organic particles or silicon organic particles, calcium carbonate, barium sulfate, titanium oxide, aluminum hydroxide, silica, glass beads, talc, mica, white carbon, magnesium oxide, Alternatively, inorganic particles such as zinc oxide may be further mixed and used.

The surface layer resin composition constituting the surface layer of the present invention comprises 1 to 25 parts by weight of an antistatic agent in the surface layer base resin consisting of 100 parts by weight of a transparent resin.

Here, the transparent resin means a resin that can be processed so that the total light transmittance of the product having a thickness of 1 mm is about 80% or more.

Examples of the transparent resin, poly methyl methacrylate (poly methyl methacrylate), alkyl (meth) acrylate (alkyl (meth) acrylate) copolymer, methyl methacrylate (methyl methacrylate)-styrene (styrene) copolymer , Polycarbonate, poly vinyl chloride, styrene-acrylonitrile copolymer, cyclo-olefin copolymer, cycloolefin polymer , Poly acrylonitrile, polyester (poly ester) or poly styrene (poly styrene) and the like.

It is preferable to use a permanent antistatic agent as the antistatic agent added to the surface layer base resin. In general, the surfactant type antistatic agent (general type antistatic agent) that is commonly used may not be properly expressed depending on the processing conditions, especially in the sheet extrusion process, which is a general process for manufacturing a light diffusion plate. This difficult problem may occur, but the permanent antistatic agent has an advantage of obtaining excellent antistatic properties regardless of the processing conditions. In addition, the general antistatic agent has a problem that the antistatic performance is sharply dropped after a certain time after the product manufacturing, there is an advantage that such a performance degradation does not appear when using a permanent antistatic agent.

Examples of the permanent antistatic agent include polyetheramides, polyetherimideamides, and polyetheresteramide antistatic agents.

When the amount of the antistatic agent is less than 1 part by weight, it is difficult to express the antistatic property, when the amount exceeds 25 parts by weight not only the problem of changing the color of the transmitted light of the final diffuser, but also the problem of increased cost due to excessive addition do.

The surface layer is laminated on at least one side of the intermediate layer, the thickness of the laminated surface layer is preferably 10 to 300 ㎛. If the thickness is less than 10 ㎛ there is a problem that the properties to be represented through the additives added to the surface layer, such as antistatic properties are not properly expressed, if the thickness exceeds 300 ㎛ there is a problem of lowering optical properties such as brightness and color and increase in cost May occur.

The intermediate layer resin composition, the surface layer resin composition, or both of the present invention containing the above components may be UV stabilizers, ultraviolet absorbers, fluorescent brighteners, lubricants, thermal stabilizers, impact modifiers, antistatic agents, antioxidants, etc. It may further include an additive selected from any one or more of a flame retardant, a mold release agent, a lubricant and a dye. In particular, in the case of the surface layer resin composition, organic particles or inorganic particles may be added for surface plate irregularities.

The heat-resistant multilayer light diffusion plate is manufactured by extruding the interlayer resin composition and the surface layer resin composition, and may be applied to a display backlight unit, a lighting device, a signboard, a glass showcase, and a light source such as a cold cathode fluorescent lamp and an LED. It can be applied to a light diffusing plate for display, such as an illumination signboard, a light cover light diffusing plate, or a direct backlight of a liquid crystal display, respectively constituting a light source device having a light source device.

As described above, the heat-resistant light diffusion plate of the present invention has a high diffusivity and brightness at the same time, has a low water absorption rate, excellent heat resistance, dimensional stability, and mechanical strength, so that the backlight for a liquid crystal display, a lighting device, a signboard, or a glass showcase It is suitable for application to the back.

The backlight unit for a liquid crystal display device of the present invention is characterized by comprising the heat-resistant multilayer light diffusion plate.

One embodiment of the backlight unit is schematically shown in cross section in FIG. 2.

The backlight unit 100 is positioned at the rear of the liquid crystal panel and provides light, for example, white light, to the liquid crystal panel. The backlight unit 100 includes a plurality of light sources 130 for providing light for illuminating a liquid crystal panel, a reflective sheet 140, a bottom chassis 150 in which the light sources and the reflective sheets are accommodated, It includes a light diffusion plate 120 and an optical sheet 110 positioned on the upper.

An optical sheet 110 is positioned on the light diffusion plate 120, and the optical sheet includes a diffusion sheet 110c, a prism sheet 110b, and a protective sheet 110a. The light passing through the light diffusion plate 120 is incident on the diffusion sheet 110c, and the diffusion sheet scatters the incident light to uniform the luminance and widen the viewing angle across the visible surface of the liquid crystal panel.

Hereinafter, preferred examples are provided to help understanding of the present invention, but the following examples are merely to illustrate the present invention, and the scope of the present invention is not limited to the following examples.

[ Example ]

Example  One

Acrylic organic particles (MA1002, Nippon Shokubai) having an average particle diameter of 2.5 μm as a light diffusing agent using a styrene (95% by weight) -methacrylic acid (5% by weight) copolymer as an intermediate layer base resin and 100 parts by weight of the intermediate layer base resin 0.3 parts by weight and 0.3 parts by weight of silicon-based organic particles (MSP-S020, Nikko Rica) were added and melt-mixed in an extruder (Leistritz, 27φ, L / D = 48) to prepare pellets.

Methyl methacrylate (60%)-styrene (40%) copolymer was used as the surface layer base resin, and 15 parts by weight of permanent antistatic agent (SANYO, Pelestat) was added to 100 parts by weight of the surface layer base resin to extruder (Leistritz, 27φ, L / D = 48), and melted and mixed to prepare a pellet. The prepared intermediate layer resin composition and the surface layer resin composition were processed into a light diffusion plate having a total thickness of 2 mm and a surface layer thickness of 50 μm on each side using a multilayer structure sheet extruder.

Example  2

In Example 1, it was carried out in the same manner as in Example 1 except for using a styrene (90% by weight)-methacrylic acid (10% by weight) copolymer as the interlayer base resin as shown in Table 1.

Example  3

In Example 1, it was carried out in the same manner as in Example 1 except for using a styrene (90% by weight) -maleic anhydride (10% by weight) copolymer as the interlayer base resin as shown in Table 1.

Example  4

In Example 1, it was carried out in the same manner as in Example 1 except for using a styrene (90% by weight)-maleimide (10% by weight) copolymer as the interlayer base resin as shown in Table 1.

Example  5

In Example 1, it was carried out in the same manner as in Example 1 except for using a styrene (90% by weight) -phenylmaleimide (10% by weight) copolymer as the interlayer base resin as shown in Table 1.

Example  6

In Example 1, it was carried out in the same manner as in Example 1 except for using a styrene (90% by weight) -cyclohexylmaleimide (10% by weight) copolymer as the interlayer base resin as shown in Table 1. .

Example  7

In Example 1, as shown in Table 1, styrene (70 wt%)-methyl methacrylate (20 wt%)-methacrylic acid (10 wt%) copolymer was used as the interlayer base resin, and the intermediate layer base resin was used. The same process as in Example 1 was performed except that 0.35 parts by weight of the acrylic organic particles and 0.35 parts by weight of the silicon organic particles were mixed and added to 100 parts by weight of the light diffusing agent.

Comparative example  One

As shown in Table 1 in Example 1 was carried out in the same manner as in Example 1 except that the styrene (100% by weight) polymer was used as the interlayer base resin.

Comparative example  2

In Example 1, 0.5 parts by weight of the acrylic organic particles and 0.5 parts by weight of the silicone-based organic particles were mixed and added to 100 parts by weight of the intermediate layer base resin, which is a methyl methacrylate (100 wt.%) Polymer, as shown in Table 1 below. The same procedure as in Example 1 was conducted except for the one.

Comparative example  3

0.4 parts by weight of the acryl-based organic particles and 100 parts by weight of a light diffusing agent in 100 parts by weight of a styrene (40% by weight) -methyl methacrylate (60% by weight) copolymer as shown in Table 1 in the interlayer base resin The same procedure as in Example 1 was carried out except that 0.4 parts by weight of organic particles were added and mixed.

Comparative example  4

0.35 parts by weight of the acrylic organic particles and 100 parts by weight of a light diffusion agent in 100 parts by weight of a styrene (70% by weight)-methyl methacrylate (30% by weight) copolymer of the intermediate layer base resin as shown in Table 1 The same procedure as in Example 1 was carried out except that 0.35 parts by weight of organic particles were mixed and added.

Comparative example  5

In Example 1, as shown in Table 1, 0.4 parts by weight of the acrylic organic particles and 0.4 parts by weight of the silicon organic particles are used as a light diffusing agent, and a surface type antistatic agent is used instead of a permanent type antistatic agent (Ciba, Atmer 163). ) Was carried out in the same manner as in Example 1, except that 1.5 parts by weight was added.

division Styrene parts by weight MMA parts by weight Heat resistant monomer Light diffusing agent Antistatic Kinds Parts by weight Acrylic system Silicone Example 1 95 - Methacrylic acid 5 0.3 0.3 Permanent Example 2 90 - Methacrylic acid 10 0.3 0.3 Permanent Example 3 90 - Maleic anhydride 10 0.3 0.3 Permanent Example 4 90 - Maleimide 10 0.3 0.3 Permanent Example 5 90 - Phenylmaleimide 10 0.3 0.3 Permanent Example 6 90 - Cyclohexylmaleimide 10 0.3 0.3 Permanent Example 7 70 20 Methacrylic acid 10 0.35 0.35 Permanent Comparative Example 1 100 - - - 0.3 0.3 Permanent Comparative Example 2 - 100 - - 0.5 0.5 Permanent Comparative Example 3 40 60 - - 0.4 0.4 Permanent Comparative Example 4 70 30 - - 0.35 0.35 Permanent Comparative Example 5 95 - Methacrylic acid 5 0.4 0.4 General type

Total light transmittance (Tt), light diffusivity (Haze), moisture absorption rate, glass transition temperature, warpage characteristics, charging using the light diffusing plates prepared in Examples 1 to 7 and Comparative Examples 1 to 5 as follows. Preventability was measured and the results are shown in Table 2 below.

A) Glass transition temperature-It was measured in the range of 25 ~ 250 ℃ at a rate of 5 ℃ / min using a DSC (Differential scanning calorimeter, TA DSC 2010) instrument.

B) Moisture absorption rate-The light diffusing plates prepared in Examples 1 to 7 and Comparative Examples 1 to 5 were cut into 5 cm x 15 cm specimens, dried in an oven at 80 ° C. for 24 hours, and then dried. After measuring the weight (W _o ) and immersing the dried specimen in distilled water at room temperature for 10 days, the weight (W) of the specimen was measured to determine the water absorption rate (Wab = (WW _o ) / W _o × 100 (%)). Calculated.

C) Flexural properties-After cutting the light diffusing plates prepared in Examples 1 to 6 and Comparative Examples 1 to 5 to a size of 30 cm × 5 cm, and stored them in an oven at 60 ℃, 95% humidity for 48 hours After mounting on the BLU of the LCD-TV and covering the upper part, the lamp was turned on and left for 24 hours, and the degree of warpage (mm) was measured at both corners of the specimen.

D) Total light transmittance and light diffusivity-It was measured using a haze transmittance meter (HR-100, Murakami Color Research Laboratory) according to JIS K 7105.

ㅁ) Antistatic property-The light diffusing plates prepared in Examples 1 to 7 and Comparative Examples 1 to 5 were cut to a size of 10 cm × 10 cm, and the test piece was 23 ° C. and 50% relative humidity according to ASTM D257. After storage for 48 hours in the condition was measured using a surface resistance measuring device.

division Glass transition temperature (℃) Water absorption (%) Bending degree (mm) Total light transmittance (Tt) Light Diffusion (Haze) Surface Resistance (W / sq) Example 1 119 0.13 1.19 73.5 84.5 10 ¹¹ Example 2 130 0.22 1.08 73.2 84.5 10 ¹¹ Example 3 125 0.19 1.20 72.8 84.6 10 ¹¹ Example 4 114 0.18 1.25 72.4 84.5 10 ¹¹ Example 5 118 0.16 1.22 72.5 84.5 10 ¹¹ Example 6 116 0.15 1.18 72.1 84.5 10 ¹¹ Example 7 132 0.23 1.28 73.4 84.5 10 ¹¹ Comparative Example 1 100 0.05 2.25 73.1 84.5 10 ¹¹ Comparative Example 2 108 1.15 3.08 72.8 84.5 10 ¹¹ Comparative Example 3 104 0.63 2.69 73.3 84.5 10 ¹¹ Comparative Example 4 102 0.41 2.42 73.2 84.5 10 ¹¹ Comparative Example 5 119 0.13 1.18 73.5 84.5 10 ¹⁵

As shown in Table 2, the light diffusing plates of Examples 1 to 7 manufactured by using the heat-resistant light diffusing resin according to the present invention are lowered in optical properties such as total light transmittance and light diffusivity compared to Comparative Examples 1 to 4. Without, the glass transition temperature was high, the water absorption was low, it was confirmed that the excellent bending characteristics.

Particularly, in Comparative Example 1 using the polystyrene interlayer resin through Table 2, although the water absorption was low, the heat resistance (glass transition temperature) was low, so that warpage was large, and polymethyl methacrylate of the interlayer resin was used. In the case of Comparative Example 2 containing the main component and 60 to 30% by weight of methyl methacrylate, Comparative Examples 3 and 4 in which the resin copolymerized with styrene was used as the interlayer base resin, water absorption was observed to be high, and thus the light diffusion plate was warped The degree was found to be large.

On the other hand, as shown in the embodiment according to the present invention, the light diffusion plate using a resin copolymerized with methacrylic acid or maleic anhydride or maleimide-based monomer as an interlayer base resin has a low water absorption rate and high heat resistance, It was confirmed that the degree of warpage is not large.

In addition, in Examples 1 to 7 including the permanent antistatic agent in the surface layer base resin, the surface resistance was significantly lower than that of the comparative example 5 including the general antistatic agent, and thus, the antistatic property was excellent.

The heat-resistant multilayer light diffusion plate according to the present invention has a high diffusivity and brightness at the same time, easy to handle as a light diffusion sheet, low moisture absorption, excellent heat resistance, backlight, lighting device, signage for liquid crystal display It has an effect suitable for application to a glass showcase, or the like.

Although only described in detail with respect to the described embodiments of the present invention, it will be apparent to those skilled in the art that various modifications and variations are possible within the technical spirit of the present invention, it is natural that such variations and modifications belong to the appended claims. .

Claims (13)

(A) 80 to 99.9% by weight of a styrene monomer and 0.1 to 20% by weight of a monomer selected from the group consisting of methacrylic acid monomers, maleic anhydride monomers and maleimide monomers. An intermediate layer comprising 0.05 to 10 parts by weight of a light diffusing agent selected from the group consisting of parts by weight, and ii) acrylic organic particles and silicon organic particles; And (B) a surface layer comprising 100 parts by weight of the surface layer base resin made of a transparent resin, and ii) 1 to 25 parts by weight of a permanent antistatic agent, The surface layer is laminated on at least one side of the intermediate layer Heat-resistant multilayer light diffuser plate. The method of claim 1, The intermediate layer base resin is characterized in that the copolymer further comprises 0.1 to 30 parts by weight of methyl methacrylate monomer (based on 100 parts by weight of styrene monomer). Heat-resistant multilayer light diffuser plate. The method of claim 1, The styrene-based monomer of the intermediate layer base resin is selected from the group consisting of styrene, α-methyl styrene, ρ-bromo styrene, ρ-methyl styrene and ρ-chloro styrene Heat-resistant multilayer light diffuser plate. The method of claim 1, The maleimide monomer of the intermediate layer base resin is selected from the group consisting of maleimide, phenylmaleimide and cyclohexyl maleimide. Heat-resistant multilayer light diffuser plate. The method of claim 1, The average particle diameter of the light diffusing agent is characterized in that 1 to 20 ㎛ Heat-resistant multilayer light diffuser plate. The method of claim 1, Among the light diffusing agents, acrylic organic particles include resin particles obtained by polymerizing an acrylic monomer alone, resin particles obtained by polymerizing a monomer having at least 50% by weight of an acrylic monomer and a monomer having one double bond in a molecule capable of radical polymerization. (B) crosslinked resin particles obtained by polymerizing at least 50% by weight of acrylic monomers and monomers having at least two radical polymerizable double bonds in the molecule, and (b) at least 50% by weight of acrylic monomers, radically polymerizable double bonds in the molecule. At least one is selected from the group consisting of monomers and crosslinked resin particles obtained by polymerizing monomers having at least two or more double bonds in a molecule capable of radical polymerization. Heat-resistant multilayer light diffuser plate. The method of claim 1, In the light diffusing agent, the silicon-based organic particles are made of a skeleton of a bifunctional siloxane unit or a trifunctional siloxane unit, and are silicon-based organic particles having an organic functional group on a surface thereof. Heat-resistant multilayer light diffuser plate. The method of claim 1, The intermediate layer further includes a light diffusing agent selected from the group consisting of calcium carbonate, barium sulfate, titanium oxide, aluminum hydroxide, silica, glass beads, talc, mica, white carbon, magnesium oxide and zinc oxide. Characterized Heat-resistant multilayer light diffuser plate. The method of claim 1, The transparent resin is a polymethyl methacrylate, an alkyl (meth) acrylate copolymer, a methyl methacrylate-styrene copolymer, a polycarbonate, a polyvinyl chloride, a styrene-acrylonitrile copolymer, a cycloolefin copolymer, It is at least one member selected from the group consisting of cycloolefin polymer, polyacrylonitrile, polyester and polystyrene. Heat-resistant multilayer light diffuser plate. The method of claim 1, The intermediate layer, the surface layer, or both, the additives selected from any one or more of UV stabilizers, UV absorbers, fluorescent brighteners, lubricants, heat stabilizers, impact modifiers, antistatic agents, antioxidants, flame retardants, mold release agents, lubricants and dyes. Characterized in that it comprises Heat-resistant multilayer light diffuser plate. The method of claim 1, The permanent antistatic agent is at least one member selected from the group consisting of polyetheramide-based, polyetherimideamide-based and polyetheresteramide-based antistatic agents Heat-resistant multilayer light diffuser plate. The method of claim 1, The thickness of the surface layer resin is 10 to 300 µm, characterized in that Heat-resistant multilayer light diffuser plate. A reflective sheet, a light source, and the heat-resistant multilayer light diffusing plate of any one of claims 1 to 11 and an optical sheet Backlight unit for liquid crystal display device.

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