JP2003287626A - Acrylic resin planar material for light guide plate, method for manufacturing the same, light guide plate and surface light source device and display device containing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an acrylic resin planar material for a light guide plate which is suitable for a surface light emitting device or a front light type display device and which has decreased white defects in the resin and little transmission loss. <P>SOLUTION: The planar material is obtained by adding a plasticizer to a polymerizable source material essentially comprising methyl methacrylate and polymerizing the mixture by a cell cast plate molding method. The luminance Y (cd/m<SP>2</SP>) on the front face of the planar material obtained by a specified side light type evaluation method and the thickness X (mm) of the planar material satisfy the relation of (1): Y≤0.03X+2.4. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acrylic resin plate material used as a light guide plate for a front light of a liquid crystal display device, various surface light source devices for displays, surface lighting devices and the like, and a method for manufacturing the same. In particular, the present invention relates to an acrylic resin plate material for a light guide plate, which is obtained by a cell-cast plate manufacturing method by adding a specific plasticizer and suppresses the white turbid phenomenon (Tyndall phenomenon) inside the resin due to light incidence.

[0002]

2. Description of the Related Art Conventionally, as a light source device used for a thin signboard, a display device, a back light source (backlight) and a front light source (front light) of a liquid crystal display device, light is incident on a light guide to emit light. Surface emitting devices are known. In recent years, a surface light emitting device called a side light system, in which a light source such as a cold cathode tube or a hot cathode tube is arranged on a side surface of a light guide to emit light in an arbitrary shape or pattern, has become mainstream.

This type of light source device is required to have higher brightness and be more compact (lighter and thinner), and also be transmitted by absorption, scattering and reflection of light in the light guide. It is desirable that the loss is as small as possible, and an acrylic resin having a high light transmittance is used.

However, even when an acrylic resin is used, in the conventional case, for example, in a front light type display device in which a side light type light guide plate is disposed in front of a liquid crystal cell, the inside of the light guide plate is The presence of a transmission loss factor such as fogging tends to cause deterioration in image reproducibility such as color reproducibility of liquid crystal display and contrast.

As an acrylic resin used for a light guide and having improved transmission loss, phosphite in an acrylic resin is disclosed in JP-A-7-331018, JP-A-9-12822, and JP-A-9-25386. An acrylic resin composition has been disclosed in which the absorption of light by heat coloring during injection molding is improved by containing a compound in a specific concentration. Further, Japanese Patent Laid-Open No. 8-334626 discloses an acrylic resin light guide body that does not include a light absorbing additive such as an ultraviolet absorber, as an acrylic resin for a light guide plate with a small visible light transmission loss. ing.

Examples of the method for molding the acrylic resin plate material that is the raw material of the light guide plate include various known methods such as a casting method, an extrusion method, an injection molding method, and a heat press molding method. Also in the manufacturing method of (3), foreign matter of submicron to micron order is often mixed.

A foreign substance having a refractive index different from that of the material of the light guide plate causes uneven brightness or a defective bright spot when light is incident on the light guide plate, and therefore it is necessary to reduce the foreign substance as much as possible.

Then, Japanese Patent Laid-Open No. 8-227004,
JP-A-10-265530, JP-A-8-2484
In Japanese Patent Laid-Open No. 16 (1994), an acrylic resin composition for a light guide plate is proposed in which the size and amount of foreign matter in the acrylic resin, the type of volatile component and the remaining amount are specified. In addition, JP-A-8
JP-A-334626 discloses an acrylic light guide body which does not contain a substance having a refractive index different from that of a light entering the light guide body.

However, the acrylic resin composition for a light guide plate disclosed in the above publication reduces transmission loss due to a substance having a refractive index different from that of the light guide plate by the presence or absence of an additive and a physical method. However, it does not solve the underlying problem.

In particular, in a front light type liquid crystal display device, since an image is viewed through a light guide plate used, it is more susceptible to transmission loss and unevenness in image contrast is likely to occur.

Further, in the light guide plate manufactured by the extrusion method, the injection molding method, and the heat press molding method, thermal distortion occurs due to the temperature difference between the inside of the plate and the surface portion of the plate that occurs during cooling, which causes optical distortion and transmission loss. Can be a factor that causes.
Such optical distortion causes a problem that an image looks distorted, especially in a light guide plate for a front light.

On the other hand, in the conventional cell-cast plate-making method, as the thickness increases, a non-uniform composition distribution is likely to occur inside the acrylic resin, and unreacted residual unsaturated monomer and initiator are by-produced. There are substances having a refractive index different from that of the base material (polymethylmethacrylate) such as substances and undissolved residues of additives, and light absorption, scattering and reflection are caused by them. Therefore, in the obtained acrylic resin light guide plate, when light is incident from its end, white turbidity is confirmed inside the resin due to light scattering and reflection. Particularly, in the case of a light guide plate used for a front light type display device or a large light guide plate having a long optical path length, the transmission loss may be large.

[0013]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an acrylic resin plate material for a light guide plate which reduces white turbidity defects in the acrylic resin and has a small transmission loss. Another object of the present invention is to provide a light guide plate and a surface light emitting device having excellent light transmitting characteristics, and a front light type display device having excellent image characteristics.

[0014]

DISCLOSURE OF THE INVENTION The inventors of the present invention have earnestly sought to obtain an acrylic resin plate-like article having a small transmission loss, which is suitable for a light guide plate used for a thin signboard, a display device, a front light of a liquid crystal display device or the like. As a result of investigation, it was found that when an acrylic resin plate-like material containing a specific plasticizer was used as a light guide plate, white turbidity generated therein could be reduced, and the present invention was completed.

The present invention is an acrylic resin plate material comprising a resin containing 90 to 99 mass% of a polymer containing methyl methacrylate units as main components and 1 to 10 mass% of a plasticizer. One of the four side surfaces of the mirror surface is used as a light incident surface, and the back surface side of the plate-shaped article having a reflector film with a reflectance of 96% arranged on the three side surfaces excluding the light incident surface is separated from the back surface by 10 mm. A black plate having a brightness of 2.0 is installed, and a halogen lamp linear light having an illuminance of 95,000 to 105000 (lx) at a location 50 mm away from the light emitting surface of the light source is incident on the light incident surface to form a plate shape. When the thickness Y (cd / m ² ) of the front surface of the plate-like object obtained by the sidelight type evaluation method for measuring the brightness of the front surface of the object is X (mm), the following formula ( 1) Y ≤ 0.03X + 2.4 (1) About for light guide plate acrylic sheet-like material satisfying.

The present invention is also the method for producing an acrylic resin plate material for a light guide plate according to the present invention, which comprises a polymerizable raw material containing methyl methacrylate as a main component and a plasticizer soluble in methyl methacrylate. The present invention relates to a method for producing an acrylic resin plate material for a light guide plate, which comprises polymerizing by a cell cast plate manufacturing method.

The present invention also relates to a light guide plate made of the acrylic resin plate material of the present invention.

The present invention also relates to a surface emitting device using the above-mentioned light guide plate of the present invention.

Further, the present invention relates to a front light type display device in which the above-mentioned light guide plate of the present invention is arranged in front of an image display section.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present invention will be described below.

The acrylic resin plate-like product of the present invention is an acrylic resin plate-like product comprising a polymer containing a methyl methacrylate unit as a main component and a resin containing a plasticizer. The polymer in the present invention comprises a methacrylic polymer containing methyl methacrylate units as a main component, and is a methyl methacrylate homopolymer or a copolymer containing 50 mol% or more of methyl methacrylate units as a polymer composition. Is preferred. Examples of monomers other than methyl methacrylate for obtaining the copolymer include various vinyl-based monomers, such as methyl acrylate, ethyl (meth) acrylate, (meth)
Butyl acrylate, cyclohexyl (meth) acrylate, phenyl (meth) acrylate, benzyl (meth) acrylate, 2-ethylhexyl (meth) acrylate,
(Meth) acrylic acid esters other than methyl methacrylate such as 2-hydroxyethyl (meth) acrylate are preferred. Here, the (meth) acrylic acid ester means at least one selected from acrylic acid ester and methacrylic acid ester.

The plasticizer in the present invention is preferably soluble in methyl methacrylate, and in the case of a copolymer, it is preferably soluble in a monomer mixture containing methyl methacrylate. It is preferable that the dissolved methyl methacrylate and its monomer mixture are colorless.
Such plasticizers include dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dioctyl phthalate,
Diisooctyl phthalate, isodecyl phthalate, didecyl phthalate, and other phthalates, aromatic esters such as benzoates, sebacates, adipates, maleates, fumarates, citrates, etc. Aliphatic esters, phosphates, glycols such as ethylene glycol and propylene glycol, polyethylene glycol,
Examples thereof include polyalkylene glycols such as polypropylene glycol. Among them, a phthalic acid ester plasticizer is preferable in terms of light resistance. You may use these plasticizers individually or in mixture of 2 or more types.

The content of the plasticizer in the resin in the present invention is 1 to 10% by mass, and in this range, 3% by mass or more is preferable and 7% by mass or less is preferable. The content of the polymer containing methyl methacrylate unit as the main component in the resin is 9
0 to 99% by mass, and in this range, 93% by mass
The above is preferable and 97 mass% or less is preferable. When the content of the plasticizer is 1% by mass or more, it becomes easy to obtain an acrylic resin plate for a light guide plate having excellent transparency with a small transmission loss, and when the amount of the plasticizer is too small, such an effect is sufficiently exerted. You won't get it. In particular, this effect shows a great effect when used in the cell-cast plate manufacturing method. Further, if the amount of the plasticizer is too large, the light resistance and mechanical strength of the obtained acrylic resin plate for a light guide plate tend to be lowered, and if the content of the plasticizer is 10% by mass or less, these characteristics are good. Becomes
By using an acrylic resin obtained by using such a plasticizer, particularly a methacrylic resin, white turbid defects generated inside are reduced, light scattering and transmission loss due to reflection are suppressed, and high light transmittance is achieved. It is possible to obtain an acrylic resin plate-shaped product having the same.

The acrylic resin plate material for a light guide plate of the present invention is
Obtained by the evaluation method of the sidelight method,
It is necessary that the brightness of the front surface of the plate-shaped object satisfies the above formula (1).

Here, the method of evaluating the brightness will be described. The brightness measured by this evaluation method also indicates the degree of white turbidity inside the plate-shaped material.

The acrylic resin plate-shaped material is cut into a rectangular plane shape of 300 mm × 400 mm (optical path length 400 mm), and four side surfaces around the plate-shaped material are mirror-polished with an electric plane and a cloth coater. A reflector film (SU119, manufactured by Tsujiden Co., Ltd.) having a reflectance of 96% is arranged on three side surfaces of the four side surfaces excluding one light incident surface.

On the back side of this plate-like object, a black plate having a brightness of 2.0 is placed 10 mm away from the plate-like object. In addition, a light source of an optical fiber lighting device using a 100 W halogen lamp (light source device manufactured by Mitsubishi Rayon Co., Ltd .: ELI
100 J, optical fiber light guide, width 1 mm x length 200 mm, illuminance at a location 50 mm away from the light emitting surface of the light source: 100000 Lux) is installed parallel to the central portion in the plate thickness direction on the light incident surface.

A brightness measuring device (LS-110 manufactured by Minolta Co., Ltd.) equipped with a close-up lens (No. 122 manufactured by Minolta Co., Ltd.) was placed 350 m from the front of the plate.
Installed at positions separated by m, the luminance in the vertical direction in the central portion of the front surface of the plate-shaped object is measured, and the index of the degree of white turbidity inside the plate-shaped object is evaluated by the brightness.

When light is incident on the plate-like material, the light is guided through the acrylic resin by being transmitted and reflected. If foreign matter or non-uniform composition distribution exists inside the resin, light scattering and
Reflection occurs and cloudiness is confirmed.

Here, when the measured luminance Y does not satisfy the equation (1), that is, the right side (0.03X) of the equation (1).
If the value is larger than +2.4), the degree of white turbidity inside the acrylic resin is high, the light transmission loss due to the scattering and reflection of light is large, and a plate-like object having a superior light transmission property is obtained. I can't. In particular, in a liquid crystal display device having a diagonal length of 457 mm or more, the transmission light path length of the plate-like material that serves as the light guide plate is long, so that it is more susceptible to the transmission loss, and uneven brightness when incorporated in the device as the light guide plate. It is easy to occur.
Further, when the light guide plate is used for the front light type display device, the color reproducibility and contrast of the image are deteriorated.

Luminance Y due to white turbidity inside the plate-like material
If the acrylic resin plate material satisfies the formula (1), a light guide plate with less scattering and reflection of light inside the acrylic resin and less transmission loss can be obtained.

It should be noted that, as the plate thickness increases, the length through which light is guided increases, so that the luminance Y tends to increase.
If the formula (1) is satisfied, the performance of the light guide plate is at a level at which it can be sufficiently used.

The light guide plate made of the acrylic resin plate-like material of the present invention is suitable as a light guide plate for a surface emitting device and a front light guide plate for a large-sized liquid crystal display device having a diagonal length of 457 mm or more. Further, the light guide plate and the acrylic resin plate-like material forming the light guide plate preferably have a thickness of 5 mm or more, and 10 m.
m or more is more preferable. The acrylic resin plate-like product of the present invention can obtain a light guide plate with small transmission loss even if it is thick as described above, and as a result, a surface emitting device (surface light source) having excellent light transmitting characteristics and an excellent A display device having excellent image characteristics can be provided.

The reduced viscosity at 25 ° C. of the acrylic resin plate material for a light guide plate of the present invention is preferably 0.1 (l / g) or more, more preferably 0.2 (l / g) or more. preferable.

When the reduced viscosity is 0.1 (l / g) or more, the obtained acrylic resin plate material has a sufficiently high molecular weight, high heat resistance is obtained, and it is close to a light source lamp that emits high heat. Also, defects due to melting or deformation of the light guide plate are less likely to occur.

The acrylic resin plate material for a light guide plate of the present invention is produced by adding a plasticizer soluble in this polymerizable raw material to a polymerizable raw material containing methyl methacrylate as a main component, and performing a cell cast plate manufacturing method. It is preferable to polymerize.

Even when a thick acrylic resin plate-like material having a thickness of 5 mm or more is produced by using the cell-cast plate-making method, the inside of the plate and the plate produced during cooling are produced as compared with the extrusion method and the injection molding method. A temperature difference in the surface portion is unlikely to occur, and the occurrence of thermal strain due to the temperature difference can be suppressed. When the heat distortion in the light guide plate is large, the heat distortion becomes an optical distortion and may cause a transmission loss.
Especially in the light guide plate for a front light, if the thermal distortion is large, the image may appear distorted. Such thermal strain is more likely to occur when the thickness of the light guide plate is 10 mm or more. However, since the cell cast plate-making method hardly causes such thermal distortion, it is suitable for producing an acrylic resin plate-like material having a thickness of 5 mm or more, and further a thickness of 10 mm or more.

In the present invention, the polymerizable raw material containing methyl methacrylate as a main component may be a polymerizable raw material containing only methyl methacrylate as a monomer, or another polymerizable raw material which can be copolymerized with methyl methacrylate. It may be a polymerizable raw material containing a monomer mixture with a monomer. Further, it may be a syrup-like polymerizable raw material composed of a polymer obtained by polymerizing a part of the contained monomer or monomer mixture, and the monomer or monomer mixture.

Further, ethylene glycol di (meth) acrylate, diethylene glycol (meth) acrylate, neopentyl glycol di (meth) acrylate is provided within a range in which transparency is not impaired and a plate for light guide plate having desired characteristics can be obtained. You may add polyfunctional (meth) acrylate etc. of these.

Examples of the polymerization initiator used in the production method of the present invention include azo compounds and peroxide compounds which are soluble in the above-mentioned polymerizable raw materials. Particularly, methyl methacrylate alone or It is preferably soluble in a monomer mixture containing methyl methacrylate.

Examples of the azo compound (azo polymerization initiator) include 2,2'-azobisisobutylnitrile,
2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2,4-dimethyl-4-methoxyvaleronitrile) and the like can be mentioned.

Examples of peroxide compounds (peroxide polymerization initiators) include ketone peroxides such as methyl ethyl ketone peroxide, methyl isobutyl ketone peroxide and cyclohexanone peroxide; isobutyryl peroxide and lauroyl peroxide. , Diacyl peroxides such as benzoyl peroxide; dialkyl peroxides such as 2,5-dimethyl-2,5-di- (t-butylperoxy) hexane; 1,1-di (t-butylperoxy) -3,3,5-
Peroxyketals such as trimethylcyclohexane;
1,1,3,3-tetramethylbutyl peroxy neodecanoate, t-butyl peroxy neodecanoate, t
-Alkyl peroxy groups such as butyl peroxy neoheptanoate, t-hexyl peroxypivalate, t-butyl peroxypivalate, t-butyl peroxy-2-ethylhexanoate, t-butyl peroxyisobutyrate. Esters; di-3-methoxybutylperoxydicarbonate, di-2-ethylhexylperoxydicarbonate, bis (4-t-butylcyclohexyl) peroxydicarbonate, di-isopropylperoxydicarbonate, t-butylpercarbonate Examples include peroxycarbonates such as oxyisopropyl carbonate and t-butylperoxy-2-ethylhexyl carbonate.

These polymerization initiators may be used alone or in admixture of two or more. The amount used is appropriately set according to the polymerization conditions such as the polymerization temperature, but usually it can be set in the range of 0.0001 to 1 part by mass with respect to 100 parts by mass of the polymerizable raw material.

In the present invention, a polymerization regulator may be used if necessary. The polymerization regulator may be any compound having the action of delaying the polymerization rate, and various conventionally known compounds can be used. For example, mercaptan compounds such as n-butyl mercaptan and n-octyl mercaptan, limonene, myrcene, α-terpinene, β-
Examples thereof include terpenoid compounds such as terpinene, γ-terpinene, terpinolene, β-pinene and α-pinene, and α-methylstyrene dimer. Particularly, terpenoid compounds are preferable. These polymerization regulators may be used alone or in combination of two or more. The amount of the polymerization regulator added is 0.0 with respect to 100 parts by mass of the polymerizable raw material.
It can be set in the range of 01 to 0.05 parts by mass.

In the cell casting method of the present invention, methyl methacrylate alone, a monomer mixture consisting of two or more kinds of monomers, or a syrup (monomer and its polymer) is used as a polymerizable raw material. As a mold, a bulk polymerization is carried out in a cell such as a glass plate cell, a mirror-polished stainless steel plate cell, or a continuous stainless steel plate cell.

As a batch type cell casting method using cells such as glass plate cells and mirror-polished stainless steel plate cells, two glass plates or mirror-polished stainless steel plates and an endless vinyl chloride plate are used. A method of injecting a polymerizable raw material in which a polymerization initiator is dissolved into a space of a mold composed of a gasket, polymerizing and curing the polymerizable raw material, and removing the formed plate-shaped polymer from the mold can be mentioned. .

The initial polymerization temperature is preferably 30 to 90 ° C. and the polymerization time is preferably 0.5 to 300 hours.
The method is not limited to this range, and a method in which the polymerization is first performed at a low temperature and then the temperature is increased to continue the polymerization can be used. Then, 100 ℃ ~ 13
Polymerization is completed by heating at a high temperature of about 0 ° C. for 0.1 to 5 hours.

From the viewpoint of preventing the occurrence of defective bright spots during the preparation of the polymerizable raw material, the assembling of the cast cell, and the injection of the raw material into the cell, it is necessary to avoid the inclusion of foreign matter as much as possible. Further, the polymerizable raw material is preferably polymerized after removing foreign matters with a filter material having fine meshes (such as a membrane filter and a sintered metal filter).

The acrylic resin plate-like material of the present invention contains known stabilizers such as ultraviolet absorbers and antioxidants, and flame retardants within a range in which transparency is not impaired and a light guide plate having desired characteristics can be obtained. Alternatively, an antistatic agent or a release agent that facilitates separation of the resin plate from the mold may be added.

The surface of the acrylic resin plate-like material of the present invention may be coated with a known hard coat paint, which prevents scratches during handling and scratches due to friction with other members. it can.

Here, the front light type display device means a device in which a light guide plate is installed on the front surface (observation side) of the image display section. A general front light type display device is shown in FIG. The light guide plate 1 is installed on the front surface (observation side) of the image display unit 2 such as an LCD, and the reflection plate 5 is arranged on the rear surface of the image display unit 2. A fluorescent tube light source 3, such as a cold cathode tube or a hot cathode tube, is arranged on the side surface 11 side of the light guide plate 1, and a lamp reflector 4 for allowing the light from the fluorescent tube light source 3 to efficiently enter the side surface 11 of the light guide plate. Are arranged. Further, the surface of the light guide plate used in the front light type display device is subjected to the arrangement of micro prism lenses, antireflection treatment, antistatic treatment, surface hardening treatment, etc. according to the usage conditions by a known method.

[0052]

EXAMPLES The present invention will be specifically described below with reference to examples.

The obtained acrylic resin plate was evaluated according to the following methods.

Luminance Measurement The luminance of the front surface of the light guide plate was measured by the evaluation method described above.

Measurement of reduced viscosity 0.1 g of the obtained acrylic resin plate was added to 100 parts of chloroform.
It melt | dissolved in ml and it measured at 25 degreeC with the Ostwald viscometer.

Front Light Lighting Test The obtained acrylic resin plate was cut into a rectangle of a predetermined size, and its side surface was mirror-polished with an electric plane and a cloth coater. Reflector films (SU119 manufactured by Tsujiden Co., Ltd.) were arranged on the short side surfaces on both sides to obtain a light guide plate. Light sources (two in total) were installed at the centers of the long side surfaces on both sides of the light guide plate, and the light sources were enclosed by reflector films to form a surface emitting device. An LCD image display screen was installed on the back side of the surface light emitting device to form a front light type display device, and the contrast of the image viewed through the light guide plate at the time of lighting was visually observed at a distance of 1 m.

Example 1 5 parts by mass of dibutyl phthalate and 0.02 parts by mass of bis (4-t-butylcyclohexyl) -peroxydicarbonate as a polymerization initiator were added to 95 parts by mass of methyl methacrylate for 30 minutes. It was stirred. After degassing, length 400 mm ×
Two glass plates, each having a width of 500 mm and a thickness of 6 mm, are poured into a cell configured through an endless tube made of vinyl chloride, polymerized in a 40 ° C. hot water bath for 15 hours, and then 130 ° C.
Complete the polymerization in an air bath for 3 hours and
A resin plate having a size of 50 mm × 450 mm and a thickness of 10 mm was manufactured. The brightness and reduced viscosity of the obtained resin plate were measured and the results shown in Table 1 were obtained.

The obtained resin plate is 265 mm × 350 mm
Then, the surface emitting device was manufactured as described above, and an LCD image display screen was further installed to form a front light type display device. The light source has a diameter of 2.4 mm and a length of 370.
mm cold cathode tube (Harrison Toshiba Lighting Co., Ltd.)
MBSM24JN10WX370NLU) was used, and the tube current was turned on at 6.0 mA.

When the image viewed through the light guide plate during lighting was visually evaluated at a measurement distance of 1 m, the resin plate had good transparency and see-through property, and the image contrast was also good.

Examples 2 to 4 Resin plates were produced in the same manner as in Example 1 except that the raw material composition shown in Table 1 was changed. The acrylic resin plate raw material used here was one in which each component was uniformly dissolved.

The resin plate thus obtained was measured for brightness and reduced viscosity, and the results shown in Table 1 were obtained.

Comparative Example 1 A resin plate was produced in the same manner as in Example 1 except that the raw material composition shown in Table 1 was changed.

The brightness and reduced viscosity of the obtained resin plate were measured and the results shown in Table 1 were obtained.

Further, using the obtained resin plate, Example 1
When a front light display device similar to the above was manufactured and a lighting test was performed, the inside of the resin plate was fogged and the image appeared to be white and cloudy, and the contrast was poor as compared with Example 1.

[0065]

[Table 1]

[0066]

EFFECTS OF THE INVENTION According to the present invention, it is possible to provide an acrylic resin plate material for a light guide plate in which white turbidity defects in the acrylic resin are reduced and transmission loss is small. It is possible to provide a light guide plate, a surface light emitting device, and a front light type display device having excellent image characteristics.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a front light type display device.

[Explanation of symbols]

1 Light guide plate 2 LCD display 3 Fluorescent tube light source 4 reflector 5 reflector 11 Side of light guide plate

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) C08L 33/10 C08L 33/10 F21V 8/00 601 F21V 8/00 601Z G02F 1/13357 G02F 1/13357 F Term (reference) 2H038 AA55 BA06 2H091 FA23X FA23Z FA41X FA41Z FB02 KA10 LA17 LA18 4F071 AA33 AC05 AC10 AC15 AF30 AH19 BA03 BB01 BC07 BC17 4J002 BG051 BG071 CH022 EC056 ED036 EH086 E046 PC0200 EH46 E02136 022

Claims (8)

[Claims] 1. Main component is methyl methacrylate unit
90-99% by weight of polymer and 1-10% by weight of plasticizer
An acrylic resin plate-shaped product made of a resin, the plate-shaped product
One of the four mirror-like side surfaces is the light incident surface,
Reflection of 96% reflectance on the three side surfaces excluding the light incident surface
1 to the back side of the plate-like object on which the tar film is placed.
Install a black plate with a brightness of 2.0 at a distance of 0 mm
Illuminate the entrance surface at a distance of 50 mm from the light exit surface of the light source.
Halogen run with a degree of 95000-105000 (lx)
A line-shaped light is made incident and the brightness of the front of the plate-like object is measured.
The plate-shaped material obtained by the dry-type evaluation method
Surface brightness Y (cd / m ²) Is the thickness of the plate-shaped object X (m
m), the following formula (1) Y ≤ 0.03X + 2.4 (1) An acrylic resin plate-like material for a light guide plate that satisfies the requirements. 2. The light guide plate according to claim 1, wherein the plasticizer is at least one selected from phthalic acid esters, aromatic esters, aliphatic esters, phosphoric acid esters, glycols, and polyalkylene glycols. Acrylic resin plate. 3. A reduced viscosity of 0.10 measured at 25 ° C.
The acrylic resin plate material for a light guide plate according to claim 1 or 2, comprising a resin having a ratio of (l / g) or more. 4. The method for producing an acrylic resin plate material for a light guide plate according to claim 1, wherein a polymerizable raw material containing methyl methacrylate as a main component and a methyl methacrylate-soluble plasticizer is used as a cell. A method for producing an acrylic resin plate material for a light guide plate, which comprises polymerizing by a cast plate manufacturing method. 5. A light guide plate made of the acrylic resin plate-like material according to claim 1. 6. The light guide plate according to claim 5, wherein the light guide plate for a front light is arranged in front of the image display section. 7. A surface emitting device using the light guide plate according to claim 5. 8. A front light type display device in which the light guide plate according to claim 5 is arranged in front of an image display portion.