JP2000089032A - Light guide plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light guide plate which is excellent in formability, has little hygroscopic deformation during use, has sufficient strength, can be made thin, has a large area, and can achieve high brightness and low brightness unevenness. I do. SOLUTION: This light guide plate is made of an alicyclic structure-containing polymer resin and has a light reflection surface formed with a concave portion for reflection,
The concave portion is a light guide plate formed so as to gradually change the arrangement density thereof from sparse to dense as the distance from the light source increases, and the concave portion is formed at 70 ° to 150 °.
And a V-shaped groove having a depth of 1 μm to 1,000 μm, and the concave portion is elongated in a direction substantially perpendicular to a light incident direction at any position of the light reflecting surface. It is desirable that the groove be formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light guide plate used for a planar light source device or the like, and more particularly, to a light guide plate which is excellent in moldability, has low moisture absorption deformation in use, has sufficient strength, and is thin. The present invention relates to a light guide plate that can have a large area and achieve high luminance and low luminance unevenness.

[0002]

2. Description of the Related Art A light guide plate is one of optical members used in a planar light source device mounted on various display devices. For example, in an edge light type planar light source device, the light guide plate is introduced into the light guide plate. It plays a role of guiding light emitted from the light source while emitting the light in a direction perpendicular to the incident direction. Since the entire light exit surface of such a light guide plate serves as a direct light source for various display devices, the members need to be made of a material having high transparency in order to achieve high luminance, and the amount of emitted light In order to achieve a uniform distribution, it is required that the luminance unevenness on the light emitting surface is small.

For this reason, conventionally, a material such as polymethyl methacrylate (PMMA) or polycarbonate (PC) has been used as a material of the light guide plate, and a high brightness is achieved on the reflection surface (reflector surface) of the light guide plate. For example, it has been proposed to form a groove having a low possibility of causing light loss at the time of molding the light guide plate (for example, Japanese Patent Laid-Open Publication No. Hei.
165,504).

[0004] In order to further increase the luminance, a device for arranging the grooves so as to be gradually denser according to the distance from the light source and a device for arranging the grooves in a staggered lattice pattern have been proposed. (JP-A-6-250,025, JP-A-5-216,030).

[0005]

However, in the conventional materials such as PMMA and PC, even if the groove arrangement pattern as described above is provided, it is not sufficient because of the optical characteristics such as the refractive index and transparency of the material itself. High frontal brightness has not yet been obtained.

Also, PMMA has a high melt viscosity at the time of injection molding and is inferior in flowability. In PC, if the resin temperature is raised for the purpose of increasing the flowability, the resin may hydrolyze and foam. In the range where the arrangement of the reflection patterns is dense (the distance from the light source is long), good transferability of the groove shape cannot be obtained, and the occurrence of luminance unevenness and the front luminance decrease due to that. And other adverse effects.

Further, in recent years, as the backlight unit has become thinner and lighter year by year, the tendency of the light guide plate has been reduced.
The light guide plate has a wedge-shaped plate shape so that the thickness becomes thinner as the distance from the light source increases as the distance from the light source increases. PMs with many problems in terms of fluidity and moldability have been widely implemented from the viewpoint of high brightness and light weight in use.
MAs and PCs are becoming more difficult to use as thin and large light guide plates.

In addition, in the wedge-type light guide plate as described above, the region where the arrangement density of the grooves is dense is the region where the plate thickness is reduced. There is a concern that deformation during use as a light guide plate (warpage of the plate due to shrinkage in the direction of the light emission surface having a small surface area) becomes significant, and such dimensional deformation, strength, moldability, high brightness, There has been a demand for a light guide plate material that can satisfy the low luminance unevenness and achieve a thin and wide area.

The present invention has been made in view of the above circumstances, has excellent moldability, has little hygroscopic deformation during use, has sufficient strength, can be made thin, can have a large area, and can achieve high luminance and low luminance unevenness. It is an object to provide a light guide plate.

[0010]

Means for Solving the Problems The inventors of the present invention have made intensive studies on a light guide plate in view of such a situation. As a result, the light guide plate was molded using an alicyclic structure-containing polymer resin and formed as a reflection pattern on a reflection surface. The light guide plate having the concave portions arranged so that the arrangement density gradually increases from sparse to dense according to the distance from the light source is excellent in formability, transferability, dimensional stability, and strength even in the case of a thin and wide area. Have and high brightness,
The inventors have found that low-luminance spotting can be achieved, and have completed the present invention.

That is, the light guide plate according to the present invention is a light guide plate formed of an alicyclic structure-containing polymer resin and having a concave portion for reflection formed on a light reflecting surface, wherein the concave portion is formed by a light source. The arrangement density is gradually changed from sparse to dense as the distance increases.

Since the light guide plate according to the present invention is made of an alicyclic structure-containing polymer resin, it has excellent optical characteristics such as excellent transparency. Further, since the light guide plate is made of the alicyclic structure-containing polymer resin, a light guide plate having excellent moldability such as fluidity and heat resistance during molding and excellent transferability can be obtained. Furthermore, the light reflecting surface is molded with an alicyclic structure-containing polymer resin, and a concave portion is provided on the light reflecting surface such that the arrangement density is increased from sparse to dense as the distance from the light source increases. Accordingly, it is possible to achieve high luminance by effective use of light and to obtain a light guide plate with less luminance unevenness. Furthermore, since the alicyclic structure-containing polymer resin has excellent strength physical properties and has the characteristic of less dimensional deformation due to moisture absorption deformation, for a while, such as a wedge, it has a portion where the thickness becomes thinner, as described above. Even in a light guide plate having an arrangement pattern of concave portions, the risk of dimensional deformation such as warpage during use is reduced, and the risk of damage to the light guide plate itself is reduced. Further, since the specific gravity of the alicyclic structure-containing polymer resin is smaller than that of PMMA and PC, the weight of the light guide plate can be reduced, and the weight of the backlight unit can be reduced.

In the present invention, the shape of the concave portion provided on the light reflecting surface of the light guide plate to achieve high brightness is not particularly limited, and may be, for example, V-shaped, U-shaped, square-shaped. And a V-shaped groove are preferably used. With such a shape, it is possible to set the angle of the concave portion so that light emitted from the light emitting surface can be emitted in a more vertical direction, and the effect of the groove shape is more effective than the dot shape. This is more remarkable, and it is easier to achieve higher brightness of the light emitting surface.

Further, the dots and the grooves may have a protruding portion (relative to the reflection surface) in a peripheral portion thereof.

The shape of the V-shaped groove does not need to be a regular V-shape composed of a perfect plane and a plane, as long as the effects of the present invention can be achieved. Is also good.

In the case of a regular V-shape, the apex angle is set to θ, and in the case of a substantially V-shape, the V-shaped groove is enlarged and observed to about 500 to 1000 times, and light is clearly observed at a macroscopic level. Assume a triangle connecting two points on the left and right of the V-shaped groove where the depression from the reflective surface can be confirmed, and one point on the deepest part of the groove (if the deepest part is flat, the center of the flat part). Assuming that the groove angle formed at the deepest part is the vertex angle θ, the angle of θ is usually
70-150 °, preferably 90-130 °, more preferably 100-120 °, and the depth of the groove is usually 1-1,
000 μm, preferably 5 to 500 μm, more preferably 10 to 100 μm. When the shape of the V-shaped groove is in this range, the incident light can be appropriately reflected and emitted from the emission surface, and higher brightness of the light guide plate can be achieved more favorably.

The lengths of the two groove surfaces forming the regular V-shaped groove and the substantially V-shaped groove may be the same or different.
These lengths may be set as appropriate based on the value of the preferred groove depth at the preferred groove apex angle.

The direction of the groove is not particularly limited as long as the groove is arranged so that the arrangement density gradually increases from sparse to dense as the distance from the light source increases, and is substantially parallel to the light incident direction. It may be formed to be elongated in the vertical direction, or it may be formed to be elongated in the substantially vertical direction.

In this case, it is more preferable that the length of the groove is formed over the entire width of the light reflecting surface of the light guide plate in the direction.

The pitch interval between the point recognized as the vertex of the apex angle θ of the regular V-shaped groove and the substantially V-shaped groove and the similar point of the adjacent groove when the groove is formed to be elongated in the substantially vertical direction is as follows. At the end of the light guide plate closer to the light source, usually 50 to 10,000.
00 μm, preferably 100 to 5,000 μm, more preferably 500 to 2,000 μm, and at the opposite end of the light guide plate, usually 10 to 1,000 μm, preferably 30 to 500 μm, more preferably 50 to 10 μm.
0 μm.

Furthermore, the ratio (A) / (B) of the length of the pitch width (A) at the end of the light guide plate closer to the light source to the pitch width (B) at the end of the light guide plate on the opposite side is usually 30 /
It is 1-2 / 1, preferably 20 / 1-2 / 1, more preferably 10 / 1-3 / 1. Since the pitch of the V-shaped groove is arranged in such a range, the light incident from the light source can be reflected and emitted so that the light amount becomes uniform on any part of the issue surface, A light guide plate with less luminance unevenness can be obtained.

Further, in this case, the angle θ1 formed by the light incident side and the light incident side of the surface constituting the V-shaped groove is usually more than 90 ° and less than 170 °, preferably 120 to 165. °, more preferably 140-160
°. When the angle θ1 formed between the groove surface on the light source side and the incident direction of the light is particularly in the range of this angle, the incident light is emitted from the light exit surface of the light guide plate by the V-shaped groove by reflection close to total reflection. Therefore, it is suitable for achieving high luminance of the light guide plate.

The groove corresponding to the present invention is:
As long as it is formed on at least the light reflecting surface of the light guide plate,
Further, it may be formed on the light emitting surface. If formed at least on the light reflecting surface, the reflection efficiency of light introduced into the light guide plate and the light collection efficiency of light in the direction perpendicular to the incident direction of light are improved, and the object of the present invention is achieved. Because.

The shape of the light guide plate itself in the present invention may be a flat plate having a constant thickness, or a wedge-shaped plate whose thickness gradually decreases as the distance from the light source increases, but is preferably a wedge-shaped plate. Is more desirable in terms of achieving high luminance by effective use of light and reducing the weight of the light guide plate itself.

In this case, the thickness of the wedge-shaped plate is usually 0.5 to 10 mm, preferably 1 to 5 mm at the end close to the light source, and is usually 0.1 to 5 mm at the opposite end. It is 5 mm, preferably 0.1 to 1 mm.

The inclination angle θ2 of the light reflecting surface with respect to the light incident direction, which is determined by the thickness of both ends and the length of the light guide plate, is usually 0.1 to 15 °, preferably 0.2 to 10 °.
°. By designing the wedge-type light guide plate in such a range, it is possible to appropriately balance the thinness of the light guide plate itself and the achievement of high brightness by effective use of light.

In addition, the combination of the preferred range of the angle θ1 formed between the groove surface on the light source side and the incident direction of light and the preferred range of the inclination angle θ2 of the wedge plate achieves particularly high luminance. It is desirable to form a light reflection pattern for the purpose.

The method for manufacturing the light guide plate according to the present invention is not particularly limited, but can be formed by, for example, injection molding. This is because, according to the injection molding, a light guide plate having a reflection pattern such as grooves provided with the arrangement density in the present invention can be manufactured with high accuracy and high productivity.

[0029] In the light guide plate present invention, "light guide plate" is, in particular applications is not limited, for example, laptop, notebook, book-type,
OA such as personal computer such as palmtop type, mobile computer, word processor
Used as appliances, home appliances such as LCD TVs for wall hanging, illumination signs, display windows of pachinko machines, display windows of ATMs and other automatic teller machines, light tables, viewers, and other display devices. It refers to a light guide plate used in a planar light source device.

The alicyclic structure-containing polymer resin The alicyclic structure-containing polymer resin used in the present invention has an alicyclic structure in a main chain and / or a side chain, and has mechanical strength and heat resistance. From the viewpoint of properties and the like, those containing an alicyclic structure in the main chain are preferred.

Examples of the alicyclic structure of the polymer include a saturated cyclic hydrocarbon (cycloalkane) structure and an unsaturated cyclic hydrocarbon (cycloalkene) structure. From the viewpoints of mechanical strength, heat resistance and the like, A cycloalkane structure or a cycloalkene structure is preferred, and a cycloalkane structure is most preferred.

The number of carbon atoms constituting the alicyclic structure is not particularly limited, but is usually 4 to 30, preferably 5 to 20.
When the number is in the range of 5 pieces, more preferably 5 to 15, the properties of mechanical strength, heat resistance and moldability are highly balanced and suitable.

The proportion of the repeating unit having an alicyclic structure in the alicyclic structure-containing polymer resin used in the present invention may be appropriately selected according to the purpose of use.
00% by weight, preferably 50 to 100% by weight, more preferably 70 to 100% by weight. If the proportion of the repeating unit having an alicyclic structure in the alicyclic structure-containing polymer resin is excessively small, the heat resistance is inferior.
When the content is in the range of% by weight, mechanical strength, heat resistance, and the like are highly balanced, which is preferable.

Further, among the alicyclic structures in the alicyclic structure-containing polymer resin used in the present invention, those having a large proportion of repeating units constituting the alicyclic structure other than the norbornane structure are used as the light guide plate. Preferably, the ratio may be appropriately selected according to the purpose of use, but is usually at least 10% by weight, preferably at least 20% by weight, more preferably at least 30% by weight. This is because the larger the proportion of the repeating unit constituting the alicyclic structure other than the norbornane structure, the more the flowability and transferability of the resin at the time of molding are further improved.

The remainder other than the repeating unit having an alicyclic structure in the alicyclic structure-containing polymer resin is not particularly limited, and is appropriately selected depending on the purpose of use.

Specific examples of such a polymer resin having an alicyclic structure include (1) a norbornene-based polymer, (2) a monocyclic olefin-based polymer, and (3) a cyclic conjugated diene-based polymer. And (4) vinyl alicyclic hydrocarbon-based polymers, and hydrogenated products thereof.

Of these, preferred are norbornene-based polymers, cyclic conjugated diene-based polymers, and hydrogenated products thereof which constitute alicyclic structural units other than the norbornane structure. Norbornene-based polymers are more preferred.

(1) Norbornene-based polymer The norbornene-based polymer used in the present invention is not particularly limited, and examples thereof include JP-A No. 3-14882 and
It is a known polymer disclosed in JP-A-3-122137, and the like. Specific examples thereof include a ring-opened polymer of a norbornene-based monomer and a hydrogenated product thereof, an addition polymer of a norbornene-based monomer, and norbornene. An addition-type copolymer of a system monomer and a vinyl compound may, for example, be mentioned.

Of these, a norbornene-based polymer having an alicyclic structural unit other than the norbornane structure is preferable in order to highly balance heat resistance and moldability. For example, a norbornene-based monomer having one norbornane structure may be used. A ring-opened polymer of a norbornene-based monomer and a hydrogenated product thereof are preferable, and a hydrogenated product of a ring-opened polymer of a norbornene-based monomer containing one norbornene-based monomer having a norbornane structure is particularly preferable.

As norbornene monomers having one norbornane structure, bicyclo [2.2.1] -hept-
2-ene (common name: norbornene), 5-methyl-bicyclo [2.2.1] -hept-2-ene, 5,5-dimethyl-bicyclo [2.2.1] -hept-2-ene, 5
-Ethyl-bicyclo [2.2.1] -hept-2-ene, 5-butyl-bicyclo [2.2.1] -hept-2
-Ene, 5-hexyl-bicyclo [2.2.1] -hept-2-ene, 5-octyl-bicyclo [2.2.1]
-Hept-2-ene, 5-octadecyl-bicyclo [2.2.1] -hept-2-ene, 5-ethylidene-
Bicyclo [2.2.1] -hept-2-ene, 5-methylidene-bicyclo [2.2.1] -hept-2-ene,
5-vinyl-bicyclo [2.2.1] -hept-2-ene, 5-propenyl-bicyclo [2.2.1] -hept-2-ene, 5-methoxy-carbonyl-bicyclo [2.2. 1] -Hept-2-ene, 5-cyano-bicyclo [2.2.1] -hept-2-ene, 5-methyl-
5-methoxycarbonyl-bicyclo [2.2.1] -hept-2-ene, 5-methoxycarbonyl-bicyclo [2.2.1] -hept-2-ene, 5-ethoxycarbonyl-bicyclo [2.2 .1] -hept-2-ene,
5-methyl-5-ethoxycarbonyl-bicyclo [2.
2.1] -Hept-2-ene, bicyclo [2.2.1]
-Hept-5-enyl-2-methylpropionate, bicyclo [2.2.1] -hept-5-enyl-2-methyloctanoate, bicyclo [2.2.1] -hept-2
-Ene-5,6-dicarboxylic anhydride, 5-hydroxymethyl-bicyclo [2.2.1] -hept-2-ene,
5,6-di (hydroxymethyl) -bicyclo [2.2.
1] -Hept-2-ene, 5-hydroxy-i-propyl-bicyclo [2.2.1] -hept-2-ene, bicyclo [2.2.1] -hept-2-ene, 5,6 -Dicarboxy-bicyclo [2.2.1] -hept-2-ene, bicyclo [2.2.1] -hept-2-ene-5,
6-dicarboxylic imide, 5-cyclopentyl-bicyclo [2.2.1] -hept-2-ene, 5-cyclohexyl-bicyclo [2.2.1] -hept-2-ene, 5
-Cyclohexenyl-bicyclo [2.2.1] -hept-2-ene, 5-phenyl-bicyclo [2.2.1]-
Hept-2-ene, tricyclo [4.3.0.1
^2,5 ] -deca-3,7-diene (common name dicyclopentadiene), tricyclo [4.3.0.1 ^2,5 ]
-Dec-3-ene, tricyclo [4.4.0.1
^2,5 ] -Undeca-3,7-diene or tricyclo [4.4.0.1 ^2,5 ] -undeca-3,8-
Diene and a these partially hydrogenated product (or an adduct of cyclopentadiene and cyclohexene), tricyclo [4.4.0.1 ^{2, 5]} - undec-3-ene, tetracyclo [7.4.0. 1 ^{10, 13} . 0
^2,7 ] -Trideca-2,4,6-11-tetraene (also referred to as 1,4-methano-1,4,4a, 9a-tetrahydrofluorene), tetracyclo [8.4.0.1
^11,14 . 0 ^3,8 ] -tetradeca-3,5
7,12-11-tetraene (1,4-methano-1,
Norbornene-based monomers such as 4,4a, 5,10,10a-hexahydroanthracene).

These norbornene monomers can be used alone or in combination of two or more.

Norbornene having a norbornane structure other than one
Tetracyclo [4.4.0.1]
^2,5. 1^7,10] -Dodeca-3-ene (simply tet
Lacyclododecene), 8-methyl-tetracycline
B [4.4.0.1^2,5. 1^7,10] -Dodeca-3
-Ene, 8-methyl-tetracyclo [4.4.0.1
^2,5. 1^7,10] -Dodeca-3-ene, 8-ethyl
Le-tetracyclo [4.4.0.1^2,5. 1
^7,10] -Dodeca-3-ene, 8-methylidene-tet
Lacyclo [4.4.0.1^2,5. 1^7,10] -Do
Dec-3-ene, 8-ethylidene-tetracyclo [4.
4.0.1.^2,5. 1^7,10] -Dodeka-3-e
8-vinyl-tetracyclo [4.4.0.1
^2,5. 1^7,10] -Dodeca-3-ene, 8-pro
Phenyl-tetracyclo [4.4.0.1^2,5. 1
^7,10] -Dodeca-3-ene, 8-methoxycarboni
Le-tetracyclo [4.4.0.1^2,5. 1
^7,10] -Dodeca-3-ene, 8-methyl-8-metho
Xycarbonyl-tetracyclo [4.4.0.
1^2,5 . 1^7,10] -Dodeca-3-ene, 8-hide
Roxymethyl-tetracyclo [4.4.0.
1^2,5. 1^7,10] -Dodeca-3-ene, 8-ca
Ruboxy-tetracyclo [4.4.0.1^2,5. 1
^7,10] -Dodeca-3-ene, 8-cyclopentyl-
Tetracyclo [4.4.0.1^2,5. 1^7,10]
-Dodeca-3-ene, 8-cyclohexyl-tetracycline
B [4.4.0.1^2,5. 1^7,10] -Dodeca-3
-Ene, 8-cyclohexenyl-tetracyclo [4.
4.0.1.^2,5. 1^7,10] -Dodeka-3-e
8-phenyl-tetracyclo [4.4.0.1
^2,5. 1^7,10] -Dodeca-3-ene, pentacy
Black [6.5.1.1^3,6. 0^2,7. 0
^9,13] -Pentadeca-3,10-diene, pentacyclo
Black [7.4.0.1^3,6. 1^10,13. 0
^2,7] -Pentadeca-4,11-diene and other nor
Norbornene-based monomers with two or more bornene structures
Is mentioned.

These norbornene monomers having two or more norbornene structures are used alone or in combination of two or more.

The content of the norbornene-based monomer having one norbornene structure in the norbornene-based monomer may be appropriately selected according to the preferable ratio of the repeating unit constituting the alicyclic structure other than the above-mentioned norbornane structure. % By weight, preferably 20% by weight or more, more preferably 30% by weight or more, and the upper limit is 100% by weight.

These ring-opening (co) polymers of norbornene-based monomers can be obtained by using a norbornene-based monomer as a ring-opening polymerization catalyst, such as a metal halide such as ruthenium, rhodium, palladium, osmium, iridium, or platinum;
Using a catalyst system comprising a nitrate or acetylacetone compound and a reducing agent, or a catalyst system comprising a halide or acetylacetone compound of a metal such as titanium, vanadium, zirconium, tungsten or molybdenum, and an organoaluminum compound in a solvent, Or without solvent, usually at a polymerization temperature of -50 ° C to 100 ° C,
It can be obtained by ring-opening (co) polymerizing at a polymerization pressure of 50 kg / cm ² .

The catalyst system includes molecular oxygen, alcohol, ether, peroxide, carboxylic acid, acid anhydride, acid chloride,
By adding a third component such as an ester, ketone, nitrogen-containing compound, sulfur-containing compound, halogen-containing compound, molecular iodine, or other Lewis acid, the polymerization activity and the selectivity of ring-opening polymerization can be increased.

The hydrogenated norbornene-based polymer can be obtained by a conventional method in which a ring-opened (co) polymer is hydrogenated with hydrogen in the presence of a hydrogenation catalyst.

The addition copolymer of a norbornene-based monomer and a vinyl-based compound can be prepared, for example, by adding a monomer component in a solvent or without a solvent in the presence of a catalyst system comprising a titanium, zirconium, or vanadium compound and an organoaluminum compound. In, usually, a polymerization temperature of -50 ° C ~ 100 ° C,
It can be obtained by a method of copolymerizing at a polymerization pressure of 0 to 50 kg / cm ² .

The vinyl compound is not particularly limited as long as it can be copolymerized. For example, ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 3-methyl-1 -Butene, 3-methyl-1-pentene, 3-ethyl-1-pentene, 4-methyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-hexene, 4,4-dimethyl -1-pentene, 4
-Ethyl-1-hexene, 3-ethyl-1-hexene,
C2-C20 ethylene or α-olefin such as 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicosene; cyclobutene, cyclopentene, cyclohexene, 3,4 Cycloolefins such as -dimethylcyclopentene, 3-methylcyclohexene, 2- (2-methylbutyl) -1-cyclohexene, cyclooctene, 3a, 5,6,7a-tetrahydro-4,7-methano-1H-indene; 4-hexadiene, 4-methyl-
Non-conjugated dienes such as 1,4-hexadiene, 5-methyl-1,4-hexadiene and 1,7-octadiene; and the like are used. These vinyl compounds can be used alone or in combination of two or more.

(2) Monocyclic Cyclic Olefin Polymer Examples of the monocyclic cycloolefin polymer include, for example, cyclohexene, cycloheptene, cyclooctene and the like disclosed in JP-A-64-216216. An addition polymer of a monocyclic cyclic olefin monomer can be used.

(3) Cyclic conjugated diene-based polymer The cyclic conjugated diene-based polymer is described in, for example,
136,057 and JP-A-7-258,318, polymers obtained by 1,2- or 1,4-addition polymerization of cyclic conjugated diene-based monomers such as cyclopentadiene and cyclohexadiene; The hydrogenated product can be used.

(4) Vinyl alicyclic hydrocarbon polymer Examples of the vinyl alicyclic hydrocarbon polymer include vinyl cyclohexene and vinyl cyclohexane disclosed in JP-A-51-59,989. Polymers of vinyl alicyclic hydrocarbon monomers and hydrogenated products thereof, JP-A-63-43910, JP-A-64-1,706
For example, a hydrogenated product of an aromatic ring portion of a polymer of a vinyl aromatic monomer such as styrene and α-methylstyrene disclosed in Japanese Patent Application Laid-Open No. H10-260, etc. can be used.

The molecular weight of the alicyclic structure-containing polymer resin used in the present invention is appropriately selected according to the purpose of use.
Weight average molecular weight in terms of polystyrene measured by gel permeation chromatography of cyclohexane solution (toluene solution if polymer resin does not dissolve)
5,000 or more, preferably 5,000 to 500,00
When it is in the range of 0, more preferably in the range of 8,000 to 200,000, particularly preferably in the range of 10,000 to 100,000, the mechanical strength and the formability are highly balanced and suitable.

The glass transition temperature (Tg) of the alicyclic structure-containing polymer resin used in the present invention may be appropriately selected according to the purpose of use, but is preferably higher from the usage environment of the light guide plate. When the temperature is usually 70 ° C. or higher, preferably 80 ° C. or higher, more preferably 90 ° C. or higher, heat resistance and molding workability are highly balanced and suitable.

The alicyclic structure-containing polymer resin used in the present invention has a JI at 280 ° C. and a load of 2.16 kgf.
Melt flow rate (M
I) may be appropriately selected according to the purpose of use, but is usually 1 to 300 g / 10 min. , Preferably 5-200 g
/ 10 min. Particularly preferably, 10 to 150 g / 10 m
in. Is suitable. If the melt flow rate is too low, the temperature at which the molding material is heated at the time of molding will be higher, so that processing may be difficult.If it is too high, molding defects such as burrs may occur at the time of molding, or insufficient strength may occur. May cause damage.

The alicyclic structure-containing polymer resin used in the present invention has a refractive index of usually 1.49 or more, preferably 1.50 or more, more preferably 1.51 or more when measured at room temperature. . The higher the refractive index of the resin used in the light guide plate, the closer the total reflection angle is to the vertical direction,
The direction of reflection of the incident light on the reflecting surface can be directed more perpendicularly to the light emitting surface.

These alicyclic structure-containing polymer resins can be used alone or in combination of two or more.

Other Ingredients The alicyclic structure-containing polymer resin constituting the "light guide plate" according to the present invention may contain, if necessary, a soft polymer, other polymers, various compounding agents and fillers alone. Or a mixture of two or more.

(1) Soft Polymer The alicyclic structure-containing polymer resin constituting the “light guide plate” according to the present invention may optionally contain a soft polymer. As the soft polymer to be blended, usually 30
Refers to a polymer having a glass transition temperature (Tg) of less than or equal to ° C.
In the case of a polymer having both of m), if the lowest Tg is 30 ° C. or less, it is included in the soft polymer.

Examples of such a soft polymer include (a) an olefin-based soft polymer mainly composed of α-olefins such as ethylene and propylene, (b) an isobutylene-based soft polymer mainly composed of isobutylene, and (c) butadiene. , A diene-based soft polymer mainly composed of a conjugated diene such as isoprene, (d) a cyclic olefin-based ring-opened polymer mainly composed of a cyclic olefin such as norbornene and cyclopentene, and (e) a soft weight having a silicon-oxygen bond as a skeleton. Coalescing (organic polysiloxane), (f) α, β-
A soft polymer mainly composed of unsaturated acids and their derivatives,
(G) a soft polymer mainly composed of an unsaturated alcohol and an amine or an acyl derivative or acetal thereof,
(H) a polymer of an epoxy compound, (i) a fluorine-based rubber,
(J) Other soft polymers.

Specific examples of these soft polymers include, for example, (a) liquid polyethylene, atactic polypropylene, 1-butene, 4-methyl-1-butene, 1-hexene, 1-octene and 1-octene. A homopolymer such as decene; an ethylene / α-olefin copolymer,
Copolymers such as propylene / α-olefin copolymer, ethylene / propylene / diene copolymer (EPDM), ethylene / cyclic olefin copolymer and ethylene / propylene / styrene copolymer are exemplified.

Examples of (b) include polyisobutylene, isobutylene / isoprene rubber, and isobutylene / styrene copolymer.

(C) is a homopolymer of a conjugated diene such as polybutadiene or polyisoprene; butadiene / styrene random copolymer, isoprene / styrene random copolymer, acrylonitrile / butadiene copolymer, acrylonitrile / butadiene copolymer Unionized hydrogenated product, random copolymer of conjugated diene such as acrylonitrile / butadiene / styrene copolymer; butadiene /
Styrene block copolymer, styrene butadiene
Styrene block copolymer, isoprene styrene
Block copolymer, styrene, isoprene, styrene,
Examples include block copolymers of conjugated dienes and aromatic vinyl hydrocarbons such as block copolymers, and hydrogenated products thereof.

As (d), norbornene monomers such as norbornene, vinyl norbornene and ethylidene norbornene, or cyclobutene, cyclopentene,
Examples include a metathesis ring-opened polymer of a monocyclic olefin such as cyclooctene and a hydrogenated product thereof.

As (e), silicone rubbers such as dimethylpolysiloxane, diphenylpolysiloxane, dihydroxypolysiloxane and the like can be mentioned.

Examples of (f) include homopolymers of acrylic monomers such as polybutyl acrylate, polybutyl methacrylate, polyhydroxyethyl methacrylate, polyacrylamide, and polyacrylonitrile; acrylic monomers such as butyl acrylate / styrene copolymer; Copolymers with monomers are mentioned.

As (g), polyvinyl alcohol,
(Esterification) of polyvinyl acetate, polyvinyl polystearate, polyvinyl benzoate, polyvinyl maleate, etc.
Homopolymers of unsaturated alcohols; copolymers of (esterified) unsaturated alcohols such as vinyl acetate / styrene copolymers and other monomers, and the like.

As (h), polyethylene oxide,
Polypropylene oxide, epichlorohydrin rubber, and the like.

Examples of (i) include vinylidene fluoride rubber, ethylene tetrafluoride-propylene rubber, and the like.

Examples of (j) include natural rubber, polypeptides, proteins, and polyester thermoplastic elastomers, vinyl chloride thermoplastic elastomers, and polyamide thermoplastic elastomers described in JP-A-8-73709.

These soft polymers may have a crosslinked structure or may have a functional group introduced by modification.

In the present invention, from the viewpoint of imparting moisture resistance when the light guide plate is used in a moisture-resistant environment, the soft polymers (a), (b), and (c) among the above-mentioned soft polymers are particularly blended. This is preferable because of excellent transparency and dispersibility after the formation. Among them, the diene-based soft polymer (c) is preferable, and a hydrogenated product of the diene-based soft polymer in which the carbon-carbon unsaturated bond of the conjugated diene bond unit is hydrogenated is more preferable. Specific examples of such a soft polymer include, for example, a hydrogenated product of a homopolymer such as polybutadiene, a hydrogenated product of a random copolymer such as a butadiene / styrene copolymer; butadiene / styrene / block copolymer And hydrogenated block copolymers such as styrene / butadiene / styrene / block copolymers, isoprene / styrene / block copolymers, and styrene / isoprene / styrene / block copolymers.

In the present invention, the amount of the soft polymer in the alicyclic structure-containing polymer resin is determined so that moisture resistance is imparted when the light guide plate is used in a moisture-resistant environment. The weight ratio of the soft polymer to 100 parts by weight of the structure-containing polymer resin is preferably 0.01 to 5 parts by weight, more preferably 0.01 to 1 part by weight.

(2) Other Polymers The alicyclic structure-containing polymer resin constituting the “light guide plate” according to the present invention may be, if necessary, polystyrene, poly (meth) acrylate, polycarbonate, polyester,
Other polymers such as resins such as polyether, polyamide, polyimide and polysulfone can be blended. These other polymers can be used alone or in combination of two or more.
In addition, the ratio is appropriately selected within a range that does not impair the object of the present invention.

(3) Compounding agent A compounding agent can be added to the alicyclic structure-containing polymer resin constituting the "light guide plate" according to the present invention, if necessary.

The compounding agent is not particularly limited as long as it is generally used in the resin industry.
Examples include compounding agents such as antioxidants, ultraviolet absorbers, light stabilizers, near infrared absorbers, coloring agents such as dyes and pigments, lubricants, plasticizers, antistatic agents, and fluorescent whitening agents.

Examples of the antioxidant include phenol-based antioxidants, phosphorus-based antioxidants, and sulfur-based antioxidants. Of these, phenol-based antioxidants are preferred, and alkyl-substituted phenol-based antioxidants are preferred. Agents are particularly preferred.

As the phenolic antioxidant, conventionally known phenolic antioxidants can be used. For example, 2-t-butyl-6-
(3-t-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate, 2,4-di-
t-Amyl-6- (1- (3,5-di-t-amyl-2)
-Hydroxyphenyl) ethyl) phenyl acrylate and the like.
Acrylate compounds described in JP-A-168,643; octadecyl-3- (3,5-di-t-butyl-4)
-Hydroxyphenyl) propionate, 2,2'-methylene-bis (4-methyl-6-tert-butylphenol), 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane , 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, tetrakis (methylene-3- (3 ', 5'-di-t) -Butyl-4 '
-Hydroxyphenylpropionate) methane [that is, pentaerythrimethyl-tetrakis (3- (3,5
-Di-t-butyl-4-hydroxyphenylpropionate)], triethylene glycol bis (3- (3-t
Alkyl-substituted phenolic compounds such as -butyl-4-hydroxy-5-methylphenyl) propionate);
6- (4-hydroxy-3,5-di-t-butylanilino) -2,4-bisoctylthio-1,3,5-triazine, 4-bisoctylthio-1,3,5-triazine, 2- Octylthio-4,6-bis- (3,5-di-
triazine group-containing phenolic compounds such as t-butyl-4-oxyanilino) -1,3,5-triazine;

The phosphorus-based antioxidant is not particularly limited as long as it is generally used in the general resin industry. For example, triphenyl phosphite, diphenyl isodecyl phosphite, phenyl diisodecyl phosphite, tris ( Nonylphenyl) phosphite, tris (dinonylphenyl) phosphite, tris (2,4-di-t-
Butylphenyl) phosphite, 10- (3,5-di-
t-butyl-4-hydroxybenzyl) -9,10-dihydro-9-oxa-10-phosphaphenanthrene-
Monophosphite compounds such as 10-oxide;
4,4'-butylidene-bis (3-methyl-6-t-butylphenyl-di-tridecyl phosphite), 4,
And diphosphite-based compounds such as 4 ′ isopropylidene-bis (phenyl-di-alkyl (C ₁₂ -C ₁₅ ) phosphite). Among these, a monophosphite compound is preferable, and tris (nonylphenyl) phosphite, tris (dinonylphenyl) phosphite, tris (2,4-di-t-butylphenyl) phosphite and the like are particularly preferable.

Examples of the sulfur-based antioxidants include dilauryl 3,3-thiodipropionate, dimyristyl 3,3'-thiodipropionate, distearyl
3,3-thiodipropionate, laurylstearyl 3,3-thiodipropionate, pentaerythritol-tetrakis- (β-lauryl-thio-propionate, 3,9-bis (2-dodecylthioethyl) -2,2
4,8,10-tetraoxaspiro [5,5] undecane and the like.

These antioxidants are each used alone.
Alternatively, two or more kinds can be used in combination.
The compounding amount of the antioxidant is appropriately selected within a range not to impair the purpose of the present invention, and is usually 0.001 to 5 parts by weight, preferably 0.01 to 5 parts by weight, based on 100 parts by weight of the polymer component.
The range is 1 part by weight.

As the ultraviolet absorber, for example, 2- (2
-Hydroxy-5-methylphenyl) 2H-benzotriazole, 2- (3-t-butyl-2-hydroxy-5)
-Methylphenyl) -5-chloro-2H-benzotriazole, 2- (3,5-di-t-butyl-2-hydroxyphenyl) -5-chloro-2H-benzotriazole, 2- (3,5-di -T-butyl-2-hydroxyphenyl) -2H-benzotriazole, 5-chloro-2
-(3,5-di-t-butyl-2-hydroxyphenyl) -2H-benzotriazole, 2- (3,5-di-
benzotriazole ultraviolet absorbers such as t-amyl-2-hydroxyphenyl) -2H-benzotriazole; 4-t-butylphenyl-2-hydroxybenzoate, phenyl-2-hydroxybenzoate, 2,4
-Di-t-butylphenyl-3,5-di-t-butyl-
4-hydroxybenzoate, hexadecyl-3,5-
Di-tert-butyl-4-hydroxybenzoate, 2-
(2H-benzotriazol-2-yl) -4-methyl-6- (3,4,5,6-tetrahydrophthalimidylmethyl) phenol, 2- (2-hydroxy-5-t-octylphenyl) -2H -Benzotriazole, 2-
Bezoate UV absorbers such as (2-hydroxy-4-octylphenyl) -2H-benzotriazole;
2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-
Methoxybenzophenone-5-sulfonic acid trihydrate, 2
-Hydroxy-4-octyloxybenzophenone, 4-
Dodecaloxy-2-fodroxybenzophenone, 4-benzyloxy-2-hydroxybenzophenone, 2,
2 ′, 4,4′-tetrahydroxybenzophenone,
Benzophenone ultraviolet absorbers such as 2,2'-dihydroxy-4,4'-dimethoxybenzophenone; ethyl-2-cyano-3,3-diphenylacrylate, 2 '
Acrylate UV absorbers such as -ethylhexyl-2-cyano-3,3-diphenylacrylate; [2,
2'-thiobis (4-t-octylphenolate)]-
Metal complex UV absorbers such as 2-ethylhexylamine nickel are exemplified.

Examples of the light stabilizer include, for example, 2, 2, 6,
6-tetramethyl-4-piperidyl benzoate, bis (2,2,6,6-tetramethyl-4-piperidyl)
Sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) -2- (3,5-di-t-butyl-
4-hydroxybenzyl) -2-n-butylmalonate, 4- (3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy) -1- (2- (3
-(3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy) ethyl) -2,2,6,6-
Hindered amine light stabilizers such as tetramethylpiperidine can be mentioned.

The near-infrared absorber includes, for example, a cyanine-based near-infrared absorber; a pyrilium-based infrared absorber; a squarylium-based near-infrared absorber; a croconium-based infrared absorber;
Azurenium-based near-infrared absorber; phthalocyanine-based near-infrared absorber; dithiol metal complex-based near-infrared absorber;
Naphthoquinone-based near-infrared absorber; anthraquinone-based near-infrared absorber; indophenol-based near-infrared absorber; azimuth-based near-infrared absorber;

Further, a commercially available near-infrared absorbing agent SIR-1
03, SIR-114, SIR-128, SIR-13
0, SIR-132, SIR-152, SIR-15
9, SIR-162 (Mitsui Toatsu Dye), Kay
assorb IR-750, Kayasorb IRG
-002, Kayasorb IRG-003, IR-
820B, Kayasorb IRG-022, Kay
asorb IRG-023, Kayasorb CY
−2, Kayasorb CY-4, Kayasorb
CY-9 (all manufactured by Nippon Kayaku) and the like.

The dye is not particularly limited as long as it can be uniformly dispersed and dissolved in the polymer component, but oil-soluble dyes (various CI solvent dyes) are widely used.
Specific examples of oil-soluble dyes include The Society
of Diyes and Colorists, published by C
color Index vol. Various C.3 described in C.3. I. Solvent dyes.

Examples of the pigment include a diarylide pigment such as Pigment Red 38; Pigment Red 48:
2, Pigment Red 53, Pigment Red 57: 1
Pigment Red 144, Pigment Red 166, Pigment Red 220, Pigment Red 221, Pigment Red 248, etc .; Condensed Azo Lake Pigments; Pigment Red 171, Pigment Red 175, Pigment Red 176, Pigment Red 1
85, penzimidazolone pigments such as Pigment Red 208; quinacridone pigments such as Pigment Red 122; Pigment Red 149, Pigment Red 17
8, perylene pigments such as Pigment Red 179; and anthraquinone pigments such as Pigment Red 177.

When the light guide plate produced by the method of the present invention requires coloring, any of dyes and pigments can be used within the scope of the present invention, and is not limited, but may have microscopic optical characteristics. In the case of a light guide plate which causes a problem, coloring with a dye is preferred. Also, the ultraviolet absorber may show a yellow to red color visually, and the near infrared absorber may show a black color visually, so there is no need to use these dyes strictly distinguished from each other. Further, they may be used in combination.

As the lubricant, an organic compound such as an ester of an aliphatic alcohol, an ester or a partial ester of a polyhydric alcohol, and inorganic fine particles can be used. Examples of the organic compound include glycerin monostearate, glycerin monolaurate, glycerin distearate, pentaerythritol monostearate, pentaerythritol distearate, and pentaerythritol tristearate.

As other lubricants, generally, inorganic particles can be used. Here, the inorganic fine particles include oxides, sulfides, hydroxides, nitrides, halides, carbonates, sulfates, and acetates of elements belonging to Groups 1, 2, 4, and 6 to 14 of the periodic table. And particles of phosphate, phosphite, organic carboxylate, silicate, titanate, borate and hydrates thereof, composite compounds mainly containing them, and natural compounds.

As the plasticizer, for example, tricresyl phosphate, trixylyl phosphate, triphenyl phosphate, triethyl phenyl phosphate, diphenyl cresyl phosphate, monophenyl dicresyl phosphate, diphenyl monoxylenyl phosphate Phosphate triester plasticizers such as phosphate, monophenyldixylenyl phosphate, tributyl phosphate and triethyl phosphate; dimethyl phthalate, dibutyl phthalate, diheptyl phthalate, di-n-octyl phthalate, di-phthalate 2-ethylhexyl, diisononyl phthalate, octyldecyl phthalate,
Phthalate ester plasticizers such as butyl benzyl phthalate; fatty acid monobasic ester plasticizers such as butyl oleate and glycerin monooleate; dihydric alcohol ester plasticizers; oxy acid ester plasticizers
Among them, a phosphoric acid triester plasticizer is preferable, and tricresyl phosphate and tricillyl phosphate are particularly preferable.

Further, as the plasticizer, a hydrocarbon polymer liquid at room temperature or a liquid low molecular weight hydrocarbon is preferably used. Among these, a linear or branched liquid hydrocarbon polymer having no hydrocarbon ring in the main chain is preferable. The weight average molecular weight of the liquid hydrocarbon polymer or liquid low molecular weight hydrocarbon is preferably 10,
000 or less, more preferably 200 to 8,000, particularly preferably 300 to 4,000. Specific examples of the liquid hydrocarbon polymer include polyisobutene, hydrogenated polybutadiene, hydrogenated polyisoprene, and the like.
Specific examples of the liquid low molecular weight hydrocarbons, squalane _(C 30 _{H 62,} molecular weight = 422.8), liquid paraffin (ISOVG10 defined in white oil JIS-K2231, ISO VG15, ISO VG3
2, ISO VG68, ISOVG100, VG8 and VG21). Among these, squalane, liquid paraffin, and polyisobutene are preferred.

Examples of the antistatic agent include long-chain alkyl alcohols such as stearyl alcohol and behenyl alcohol, and fatty acid esters of polyhydric alcohols such as glycerin monostearate and pentaerythritol monostearate. Stearyl alcohol and behenyl alcohol are particularly preferable. preferable.

These compounding agents can be used alone or in admixture of two or more, and the ratio is appropriately selected within a range not to impair the object of the present invention. The amount is appropriately selected within a range that does not impair the object of the present invention, and is usually 0.001 to 5 parts by weight, preferably 0.01 to 1 part by weight, based on 100 parts by weight of the polymer component. .

In the present invention, the above-mentioned polymer component is used by mixing the above-mentioned components as necessary. The mixing method is not particularly limited as long as these compounding agents are sufficiently dispersed in the polymer component. For example, a method of kneading a resin in a molten state with a mixer, a twin-screw kneader, a roll, a Brabender, an extruder, or the like, dissolving and dispersing in a suitable solvent, coagulating, casting, or directly drying a solvent. There is a method of removing. When using a twin-screw kneader,
After kneading, the mixture is usually extruded into a rod in a molten state, cut into an appropriate length by a strand cutter, and pelletized.

Molding Method Melt molding is preferred as the method for molding the “light guide plate” made of the alicyclic structure-containing polymer resin according to the present invention, and hot press molding and injection molding are preferred. It is preferable from the viewpoint of moldability and productivity.

In the present invention, the resin temperature during injection molding is:
Usually 230 to 360 ° C, preferably 260 to 340 °
It is appropriately selected in the range of C. If the resin temperature is excessively low, the fluidity will deteriorate, and the molded product will have sink marks and distortion.If the resin temperature is excessively high, silver streaks will occur due to thermal decomposition of the resin, and the molded product will turn yellow, etc. Failure may occur.

For the purpose of minimizing the above-mentioned molding failure, the molding resin is usually prepared in advance for 6 hours or less, preferably for 4 hours or less.
It is preferable that the preliminary drying is performed within an hour, more preferably within 2 hours.

The mold temperature is usually set at a temperature lower than the glass transition temperature (Tg) of the polymer having an alicyclic structure.
Preferably, the resin has a Tg-10 (° C) to a Tg-80 (° C).
C) range, more preferably Tg-20 (° C) to Tg
It is set at a temperature in the range of −60 (° C.). By setting the mold temperature in such a range, the distortion of the molded product can be suppressed to a low level.

The injection speed is usually 20 cm ³ / sec
１００100 cm ³ / sec. Injection speed is 20cm
^If it is less than ³ / sec, it is difficult to mold a light guide plate having a relatively large screen size (10 inches or more) with high surface accuracy, which causes uneven brightness.

The injection pressure is usually 500 to 1500 kgf
/ Cm ² may be appropriately selected and set in consideration of conditions such as the design of the mold, the fluidity of the alicyclic structure-containing polymer resin to be used, and the like.

The holding pressure is a pressure applied for a certain period of time after the mold is substantially filled by the injection pressure until the gate portion of the mold is completely cooled and solidified. The upper limit of the holding pressure is generally set within the range of the mold clamping pressure of the mold.
2000 kgf / cm ² or less, preferably 1700 k
gf / cm ² or less, more preferably 1500 kgf /
It is set in the range of cm ² or less. By setting the upper limit of the holding pressure in such a range, there is no possibility that molding failure such as distortion occurs in the molded product. The lower limit of the pressure holding at least 100 kgf / cm ² or higher, preferably 120 kgf / cm ² or more, more preferably 15
It is set in the range of 0 kgf / cm ² or more. By setting the lower limit of the holding pressure in such a range, the occurrence of sink in the light guide plate as a molded product can be prevented, the molding shrinkage can be reduced, and a light guide plate with excellent dimensional accuracy can be obtained. .

[0103]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments shown in the drawings.

In this embodiment, the light guide plate according to the present invention is used as an edge light type planar light source device 1 for various display devices.
Will be described.

FIG. 1 is a schematic perspective view showing one planar light source device using the light guide plate according to the present embodiment, FIG. 2 is a partial cross-sectional view when viewed from the X direction in FIG. 1, and FIG. It is the elements on larger scale of II of FIG.

As shown in FIG. 1, the planar light source device 1 according to the present embodiment includes a light guide plate 2 and a light source 4 disposed on at least one side of the light guide plate 2.

As the light source 4, a fluorescent lamp of a cold cathode tube or a hot cathode tube can be exemplified, and a cold cathode tube is preferably used because power consumption is small. For high brightness and thinness,
The light source 4 is also preferably a thin tube having a high brightness with a tube diameter of 6 to 2 mm.
mm and a screen luminance of 15000 cd / m ² or more are more preferable. In addition, the color temperature of the light source 4 (what color the light source 4 is colored in, expressed by temperature (° K: Kelvin)) is determined by the appearance of light emitted from the emission surface 2b of the light guide plate 2. The light emitted from the emission surface 2b has a color temperature of 7000 to 8000 ° K, preferably 740
It is desirable to use a light source having a temperature of about 0 to 7500 ° K.

In addition to the above members, although not shown, a lamp reflector arranged so as to surround the light source 4 and for efficiently guiding the light source light not directly incident on the light source side end face 2a of the light guide plate 2 to the light guide plate 2 efficiently. Also, a reflection sheet disposed on the light reflection surface 2c side of the light guide plate 2 and returning the light leaking from the light guide plate 2 back into the light guide plate 2 is also a member constituting the planar light source device in the present embodiment. . If desired, a light-collecting sheet and a diffusion sheet may be further disposed above the light exit surface 2b.

As shown in FIGS. 1 and 2, the light guide plate 2 is a member for guiding the light of the light source 4 incident from the light incident surface 2a in the longitudinal direction and emitting the light from the light exit surface 2b without uneven brightness. And an alicyclic structure-containing polymer resin.

As shown in FIGS. 1 and 2, the light guide plate 2 does not gradually decrease in thickness as the cross section goes away from the light source 4 side (substantially perpendicular to the axis of the linear light source). It has a rust shape.

As shown in FIGS. 1 and 2, the light guide plate 2 is provided on the light reflecting surface 2c side of the light guide plate 2 so that the light introduced from the light source 4 is uniformly emitted. The V-shaped groove 22 is elongated in a direction substantially perpendicular to the direction away from the light source (in a direction substantially parallel to the axis of the linear light source). The V-shaped groove 22 is formed so as to be gradually denser from the light source 4 side of the light guide plate 2 to the end portion.

[0112] As shown in FIG. 2, the pitch _{P 1} between the V-shaped grooves 22 and 22 adjacent in this embodiment typically 50μm~10,000μm at the end closer to the light source,
It is preferably 100 μm to 5,000 μm, more preferably 500 μm to 2,000 μm, and in the vicinity of the opposite end, usually 10 μm to 1,000 μm, preferably 30 μm to 500 μm, more preferably 50 μm.
m to 100 μm. In addition, adjacent V-shaped grooves 22,
The pitch _{P 1} of the light guide plate 2 2a side between 22, the ratio of the pitch _{P 1} of 2d side 10: 1 to 3: and most preferably 1. The depth H1 of the V-shaped groove 22 is ₁ μm to ₁ ,
000 μm. The angle θ of the V-shaped groove 22 is 70
° to 150 °.

[0113] Further, as shown in FIG.
The angle θ1 formed between the light source side surface 22a of the surface constituting the second light source and the light incident direction is in a range of more than 90 ° and less than 170 °.

It is preferable to set the V-shaped groove in the light guide plate 2 in the above range in order to improve the reflection efficiency of the light from the light source and to increase the brightness on the light emitting surface.

The light guide plate having such V-shaped grooves 22 is integrally formed by injection molding.

If the V-shaped groove 22 having the specific shape described above is not transferred accurately, it causes brightness unevenness, a reduction in reflection efficiency, a reduction in light collection efficiency, and the like. Since it is composed of the alicyclic structure-containing polymer resin, it has excellent fluidity at the time of melting. Even if the V-shaped groove 22 is integrally formed by injection molding, it does not cause transfer failure and has a good shape. The V-shaped groove 22 can be formed in the light guide plate.

The present invention is not limited to the above-described embodiment, but can be variously modified within the scope of the present invention. For example, in the above embodiment, the V-shaped groove 2
2 is formed only on the light reflection surface 2c side of the light guide plate, but is not limited thereto, and may be formed on both surfaces (light reflection surface and light emission surface) of the light guide plate.

The wedge-shaped shape of the light guide plate 2 corresponds to the light source side surface 2a.
0.5 to 10 mm on the opposite side 2d.
1 to 5 mm. The inclination angle θ2 of the reflection surface 2c of the light guide plate 2 is in the range of 0.1 to 15 ° (see FIG. 2).

[0119]

EXAMPLES Hereinafter, the present invention will be described based on more detailed examples in comparison with comparative examples, but the present invention is not limited to these examples. In the following examples, “parts” and “%” are based on weight unless otherwise specified.

In the following Production Examples, Examples and Comparative Examples, the methods for measuring various physical properties are as follows.

(1) Regarding the physical properties of the resin, weight average molecular weight (Mw), hydrogenation rate of main chain and aromatic ring (nuclear hydrogenation rate), glass transition temperature (Tg), melt flow rate (MI), transparency And the refractive index were measured. Here, "M
“w” represents gel permeation chromatography (GPC) using cyclohexane as a solvent unless otherwise specified.
As a polyisoprene conversion value. “Hydrogenation rate of main chain and aromatic ring (nuclear hydrogenation rate)” is ¹ H
-Measured by NMR. "Tg" is JIS-K71
21. "MI" is JIS
280 ° C, 2.16kgf based on -K6719
The load was measured. "Refractive index" is ASTM-D542
It measured according to.

(2) "Transparency" was measured using a spectrophotometer (product number U-30 manufactured by JASCO Corporation) at a wavelength of 400 to 90.
The light transmittance (%) was measured while continuously changing the wavelength in the range of 0 nm, and the minimum transmittance was measured as the light transmittance of the light guide plate. (3) The “brightness” was determined by comparing the molded light guide plate with a diffusion sheet on the light emitting surface side of PC manufactured by Kimoto Co., Ltd.
The average luminance was measured in a form in which one sheet of OMX and one sheet of BEF90 manufactured by Sumitomo 3M Ltd. were laminated as a prism sheet. The average luminance was measured using a luminance meter (BM-7: manufactured by Topcon Corporation) on the light-emitting surface of the light guide plate (a rectangular surface 1.5 cm inside from the periphery of the molding surface of the light guide plate) having the above sheet structure. The luminance (vertical direction) of a total of 9 points at equal intervals with respect to the short side was measured, and the average was calculated.

(4) “Luminance unevenness” is measured at nine points (vertical direction) in the same manner as in the above (2), and evaluated by luminance unevenness = (minimum value / maximum value). Was regarded as good.

(5) The “moisture absorption deformability” was measured by measuring a dimensional change before and after a standing test in a humidity environment. The test condition was left in a high-temperature and high-humidity tank at 50 ° C. and a humidity of 60% for one week, and the presence or absence of moisture absorption deformation (warpage) of the light guide plate was confirmed. “◎” indicates no warpage, “○” indicates a dimensional change due to warp of more than 0% and less than 0.3%, and “△” indicates a dimensional change of 0.3% or more and less than 1.0%. Those having a dimensional change of 1.0% or more were evaluated as "x".

(6) “Strength” refers to the molding material used for the light guide plate.
The IZOD strength of the material is measured according to JIS K7110.
Was evaluated. As a test piece, a notched
A No. 2 A test piece was used. Evaluation is the average of 10 measurements.
Is 2.0kgf · cm / cm ²The above is "○",
1.5kgf · cm / cm²2.0kgf ・ c
m / cm²Less than "△", 1.5kgfcm
/ Cm²Those less than were rated "x".

(7) "Moldability" was evaluated according to the following criteria by visually judging a molded product (light guide plate). "O": no foaming, sink marks, and silver streaks in 10 injection moldings "O": 1 to 2 samples showing the above molding failure in 10 injection moldings "△": 3 samples in 10 injection moldings In the above, "X" indicates that the above molding failure was observed.

(8) "Transferability" was evaluated by visually observing whether or not the concave portions and the convex portions were satisfactorily transferred. "◎": no transfer failure, "不良": no transfer failure, "△" ... Some poor transfer, and “×”: noticeable poor transfer.

[Production Example 1] Under a nitrogen atmosphere, 8-ethyltetracyclo [4.4.0.1 ^2,5 . ^{17, 10} ]-
100 parts by weight of dodeca-3-ene (hereinafter abbreviated as ETCD) was polymerized with a known metathesis ring-opening polymerization catalyst system, and then hydrogenated by a known method to obtain a hydrogenated ETCD ring-opened polymer. The hydrogenated ETCD ring-opened polymer had a Mw of 42,000, a hydrogenation rate of 99.8% or more, and a Tg of 1
40 ° C., refractive index 1.53, MI 19 g / 10 mi
n. Met. 0.1 parts by weight of the pellets.
2 parts by weight of a phenolic antioxidant pentaerythrityl-tetrakis (3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate) and 0.4
Parts by weight of hydrogenated styrene / butadiene / styrene / block copolymer (ToughTech H105 manufactured by Asahi Kasei Corporation)
1, a crumb shape, a refractive index of 1.52 at 30 ° C.) were mixed and kneaded with a biaxial kneader, and a strand (rod-shaped molten resin) was passed through a strand cutter to obtain a pellet (granular) molding material. In addition, JIS-K7
When the IZOD intensity was measured based on 110, it was 10
The average value of the measurements is 3.00 (kgf · cm / c
m ² ).

[Production Example 2] Instead of 100 parts by weight of ETCD, 15 parts by weight of ETCD and tricyclo [4.3.0.
1 ^2,5 ] deca-3,7-diene (dicyclopentadiene; hereinafter, referred to as DCP) was replaced with 85 parts by weight (100 parts by weight in total) in the same manner as in Production Example 1 except that ETCD /
A hydrogenated DCP ring-opening copolymer was obtained. The copolymerization ratio of each norbornene in the polymer is determined by the composition of the residual norbornene in the solution after polymerization (by gas chromatography).
ETCD / DCP = 15/85, which was almost equal to the charged composition. The hydrogenated ETCD / DCP ring-opening polymer had a Mw of 40,000, a hydrogenation rate of 99.8% or more, a Tg of 104 ° C., and a refractive index of 1.5.
3, MI is 20 g / 10 min. Met. When the IZOD strength of this molding material was measured based on JIS K-7110, the average value of ten measurements was 3.15 (kgf · cm / cm ² ).

Example 1 As a molding material, a pellet of the hydrogenated ETCD ring-opened homopolymer prepared in Production Example 1 was injection-molded using a mold in which a V-shaped groove was previously arranged. A light guide plate was manufactured. The molding conditions for the injection molding were as follows, using an injection molding machine of product number IS450 manufactured by Toshiba Machine Co., Ltd.
0 ° C, cylinder temperature 290 ° C, nozzle temperature 260
° C, injection pressure 1000kgf / cm ² , holding pressure 800k
gf / cm ² , mold clamping pressure 1200 kgf / cm ² , injection speed (corresponding to screw advance speed) 40 cm ³
/ S. As shown in FIG. 1, each of the obtained light guide plates has a thickness of 2 mm at one end (2a side) and 2 mm at the end (2a).
d side) is 0.5 mm, the length from one end to the end is 190 mm, and the length along the axial direction of the linear light source is 2
It was 50 mm, and was wedge-shaped so that the thickness gradually decreased in the direction away from one end side to the end side (direction substantially perpendicular to the axis of the linear light source). On the light reflection surface 2c side of the light guide plate, it is elongated in a direction substantially perpendicular to the direction away from the light source 4 side (direction substantially parallel to the axis of the linear light source), and from one end side to the end side of the light guide plate. The V-shaped groove 22 that gradually becomes denser as the distance increases is excellently formed without transfer failure. In addition, foaming,
Molding defects such as sink marks and silver streaks were not observed.

Note that, as shown in FIG.
Is an angle of a top angle θ of 110 °, an angle of θ1 is about 145 °,
Groove width 0.2 mm, pitch width near light source 0.5-2 m
m, the pitch width near the end is 0.05 to 0.1 mm, and the groove depth is approximately 50 μm from near the light source to near the end.
m.

The light transmittance of the light guide plate was measured.
The minimum light transmittance from 00 nm to 900 nm is 9
0.0%, and the transparency was good.

An edge light type planar light source unit was manufactured using each of the obtained light guide plates. Specifically, a reflection tape of product number RF188 manufactured by Tsujimoto Electric Machine Co., Ltd. was adhered to the side end surface other than the light incident end surface of each light guide plate, and Harrison Electric Co., Ltd. was attached to the short side light incident end portion. A cold cathode lamp having a tube diameter of 2.4 mmφ was installed, and the surroundings of the lamp and the light incident portion of the light guide plate were covered with a reflector of product number GR38W manufactured by Kimoto Corporation. In addition, a product number P manufactured by Tsujimoto Electric Manufacturing Co., Ltd. is provided on the light exit surface side of the light guide plate.
A light diffusing sheet of CM100MX and a prism sheet BEF90 manufactured by Sumitomo 3M Co., Ltd. are placed on the surface opposite to the light exit surface of the light guide plate, and a product number RF manufactured by Tsujimoto Electric Machine Co., Ltd.
188 reflection sheets were arranged to form an edge light type planar light source unit.

Table 1 summarizes the results of evaluation of the average luminance, luminance unevenness, and hygroscopic deformation using this unit.

Example 2 As a molding material, the ETCD / DCP prepared in Production Example 2 was used.
= 15/85 Ring-opened polymer hydrogenated pellets were injection-molded under the same molding conditions using the same mold as in Example 1 to produce a light guide plate. The obtained light guide plate was a wedge type having the same size and shape as in Example 1, and the similar V-shaped groove was formed integrally without any transfer failure and well. In addition, in ten injection moldings, molding defects such as foaming, sink marks and silver streaks were not observed. When the light transmittance of the light guide plate was measured, it was 400 to 9
The minimum light transmittance at 00 nm was 90.2%, and the transparency was good. Using the obtained light guide plate,
An edge light type planar light source unit was prepared in the same manner as in Example 1, and the average luminance, the luminance unevenness, and the hygroscopic deformation were evaluated. The results are summarized in Table 1.

Comparative Example 1 The ETCD / DCP prepared in Production Example 2 was used as a molding material.
= Injection molding of 15/85 ring-opened polymer hydrogenated pellets using a mold in which V-shaped grooves are previously arranged in a pattern different from those in Examples 1 and 2 under the same molding conditions. The light guide plate was created by the method. The obtained light guide plate was wedge-shaped and had the same size and shape as in Example 1. A V-shaped groove having the same shape was formed from the light source side to the end on the opposite side.
The pitch was formed at a constant pitch width of 0.5 mm corresponding to an average pitch width of ２2. There was no transfer failure of the groove at all, and it was well formed integrally. In addition, in ten injection moldings, molding defects such as foaming, sink marks and silver streaks were not observed. When the light transmittance of the light guide plate was measured, the minimum light transmittance at 400 to 900 nm was 90.2%, and the transparency was good. Using the obtained light guide plate, an edge light type planar light source unit was prepared in the same manner as in Example 1, and the average luminance, luminance unevenness, and moisture absorption deformability were evaluated. The results are summarized in Table 1.

Comparative Example 2 Polymethyl methacrylate (PMMA) (product number SUMIPEX MG5 manufactured by Sumitomo Chemical Co., Ltd.) was used as a molding material instead of using the pellets of Production Examples 1 and 2, and the same as in Examples 1 and 2. A pellet was produced and used by the method described above.
When the IZOD strength of this molding material was measured in the same manner as in Examples 1 and 2, the average value was 1.60 (kgf · cm / cm).
² ). Using this molding material, a light guide plate was produced under the same mold and the same molding conditions as in Examples 1 and 2. The obtained light guide plate was wedge-shaped and had the same size and shape as those in Examples 1 and 2, but the wedge-shaped tip had defective transfer of V-shaped grooves. Further, such a molding failure is observed in all of the 10 injection moldings, and among 10 samples, 3 of the samples have sink marks at the tips of the wedges, and silver streaks due to resin foaming are observed in all of the samples. The result was. When the light transmittance of the light guide plate was measured, the minimum light transmittance at 400 nm to 900 nm was 90.0%, which was a good result in terms of transparency. Using the obtained light guide plate, an edge light type planar light source unit was prepared in the same manner as in Example 1, and the average luminance, luminance unevenness, and moisture absorption deformability were evaluated. The results are summarized in Table 1.

Comparative Example 3 Polycarbonate (PC) (product No. Panlite-122 manufactured by Teijin Chemicals Ltd.) was used instead of the pellets of Production Examples 1 and 2 as the molding material. Pellets were manufactured by the method and used. I of this molding material
When the ZOD intensity was measured in the same manner as in Examples 1 and 2, the average value was 5.90 (kgf · cm / cm ² ). Using this molding material, a light guide plate was produced under the same mold and the same molding conditions as in Examples 1 and 2. The obtained light guide plate was wedge-shaped and had the same size and shape as those in Examples 1 and 2, but the wedge-shaped tip had defective transfer of V-shaped grooves. Further, such a molding failure was observed in all of the 10 injection moldings, and 6 out of 10 samples resulted in sink marks at the tip of the wedge mold. In addition, foaming and silver streaks considered to be due to hydrolysis of the resin were observed in all the samples.
When the light transmittance of the light guide plate was measured, the light transmittance was 400 nm to 9%.
The minimum light transmittance at 00 nm was 82.5%, which was slightly poor in transparency. Using the obtained light guide plate, an edge light type planar light source unit was prepared in the same manner as in Example 1, and the average luminance, luminance unevenness, and moisture absorption deformability were evaluated. The results are summarized in Table 1.

[0139]

[Table 1]

Examples 3 to 12 As molding materials, Production Example 1 (Examples 3 to 7), Production Example 2
The pellets of the hydrogenated ETCD / DCPD ring-opening copolymer prepared in (Examples 8 to 12) are injection-molded under the same molding conditions using the same molds as in Examples 1 and 2, respectively. The light guide plate was produced. Each of the obtained light guide plates had a wedge shape similar to that of Examples 1 and 2. Further, on the light reflecting surface side of the light guide plate, similarly to the first and second embodiments, the light guide plate is elongated in a direction substantially perpendicular to the direction away from the light source 4 side, and gradually increases from one end side to the end side of the light guide plate. The dense V-shaped grooves were formed without any transfer failure in Examples 3 to 7, and were completely integrated with no transfer failure in Examples 8 to 12. As shown in FIG. 2, the V-shaped groove 22 has a groove width,
The pitch width and groove depth near the light source and near the end were the same as in Examples 1 and 2.

Each angle of the V-shaped grooves 22 is 75 °.
(Examples 3 and 8), 95 ° (Examples 4 and 9),
110 ° (Examples 5 and 10), 125 ° (Example 6)
And 11) 145 ° (Examples 7 and 12). When the total light transmittance of each light guide plate was measured, 90.0% was obtained for Examples 3 to 7, and Examples 8 to 1 were obtained.
2 was 90.2%, and the transparency was good. Using the obtained light guide plate, the same edge light type planar light source unit as in Examples 1 and 2 was produced. Table 2 shows the results of evaluating the average luminance, luminance unevenness, and hygroscopic deformation property using this unit.

[0142]

[Table 2]

Examples 13 to 22 As molding materials, pellets of the hydrogenated ETCD ring-opened homopolymer prepared in Production Example 1 (Examples 13 to 17) and Production Example 2 (Examples 18 to 22) were used. A light guide plate was manufactured by injection molding using the respective molds that differed only in the depth of the V-shaped groove under the same molding conditions as in Examples 1 and 2. Each of the obtained light guide plates was obtained in Examples 1-2.
It had a wedge shape similar to that of.

Note that, as shown in FIG.
Except for the depth, the angle was 110 °, the groove width was 0.2 mm, the pitch width near the light source was 0.5 to 2 mm, and the pitch width near the terminal was 0.05 to 0.1 mm. The depth of the V-shaped groove 22 is uniformly 3 from the vicinity of the light source to the vicinity of the end.
0 μm (Examples 13 and 18), 40 μm (Example 1)
4 and 19), 60 μm (Examples 15 and 20),
It was 80 μm (Examples 16 and 21) and 100 μm (Examples 17 and 22).

When the total light transmittance of each light guide plate was measured, it was 90.0% for Examples 13 to 17 and 90.2% for Examples 18 to 22, indicating that the transparency was good. . Examples 1-2 using the obtained light guide plate
An edge light type planar light source unit similar to that described above was produced. Table 3 shows the results of evaluation of luminance and luminance unevenness using this unit.

[0146]

[Table 3]

Consideration (1) Comparison between Example and Comparative Example From Table 1, the units using the light guide plates (polymer resin containing an alicyclic structure) of Examples 1 and 2 are better than those of Comparative Examples 2 and 3. Compared to a unit using a light guide plate (PMMA, PC), it was confirmed that the luminance was high, there was no luminance unevenness, and the hygroscopic deformation property was excellent. Further, from Table 1, the unit using the light guide plate of Example 2 (the pitch of the grooves can be changed from sparse to dense) can be compared with Comparative Example 1
It was confirmed that the luminance unevenness was smaller than that of the unit (the pitch of the grooves was equally spaced).

(2) Comparison between Examples From Table 2, it can be seen from Table 2 that the units using the light guide plates of Examples 8 to 12 are superior to the units of Examples 3 to 7 in groove transferability and high. The brightness was confirmed. From Table 3, it was confirmed that the units using the light guide plates of Examples 18 to 22 had better groove transferability and higher brightness than the units of Examples 13 to 17.

[0149]

Since the light guide plate according to the present invention is made of an alicyclic structure-containing polymer resin, it has excellent optical properties such as excellent transparency. Further, since the light guide plate is made of the alicyclic structure-containing polymer resin, a light guide plate having excellent moldability such as fluidity and heat resistance during molding and excellent transferability can be obtained. Furthermore, the light reflecting surface is molded with an alicyclic structure-containing polymer resin, and a concave portion is provided on the light reflecting surface such that the arrangement density is increased from sparse to dense as the distance from the light source increases. Accordingly, it is possible to achieve high luminance by effective use of light and to obtain a light guide plate with less luminance unevenness. Furthermore, since the alicyclic structure-containing polymer resin has excellent strength physical properties and has the characteristic of less dimensional deformation due to moisture absorption deformation, for a while, such as a wedge, it has a portion where the thickness becomes thinner, as described above. Even in a light guide plate having an arrangement pattern of concave portions, the risk of dimensional deformation such as warpage during use is reduced, and the risk of damage to the light guide plate itself is reduced. Further, since the specific gravity of the alicyclic structure-containing polymer resin is smaller than that of PMMA and PC, the weight of the light guide plate can be reduced, and the weight of the backlight unit can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing one planar light source device using a light guide plate according to the present embodiment.

FIG. 2 is a partial cross-sectional view when viewed from an X direction in FIG.

FIG. 3 is a partially enlarged view of II in FIG. 2;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Surface light source device 2 ... Light guide plate 2a ... Light incidence surface 2b ... Light emission surface 2c ... Light reflection surface 2d ... Edge light reflection surface 22 ... V-shaped groove 22a ... Light source side surface 4 ... Light source

Continued on the front page (72) Inventor Issei Ishimaru 1-2-1, Yakko, Kawasaki-ku, Kawasaki-shi, Kanagawa F-term in the Zeon Corporation General Development Center (reference) 2H038 AA55 BA01 2H091 FA14Z FA23Z FB02 FC17 FD06 LA11 LA12 LA17 LA18 4J032 CA23 CA24 CA27 CA28 CA34 CA35 CA36 CA38 CA43 CA45 CA46 CA62 CB01 CB03 CB12 CD02 CD05 CD09 CE22 CE23 CG02 CG07

Claims (3)

[Claims] 1. A light guide plate comprising an alicyclic structure-containing polymer resin and having a light-reflecting surface formed with a concave portion for reflection, wherein the concave portion has a gradually increasing arrangement density as the distance from the light source increases. A light guide plate formed so as to change from sparse to dense. 2. The light guide plate according to claim 1, wherein the recess is a V-shaped groove having an angle of 70 ° to 150 ° and a depth of 1 μm to 1,000 μm. 3. The light guide plate according to claim 1, wherein the concave portion is a groove which is elongated in a direction substantially perpendicular to a light incident direction at any position on the light reflecting surface.