JP2008221507A - Optical resin sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical resin sheet suitable for a display device such as a liquid crystal display device, an organic EL display device, electronic paper, etc., reduced in the coefficient of linear expansion and excellent in dimensional stability. <P>SOLUTION: The optical resin sheet contains a transparent resin, a fiber fabric and a rod-like substance and is characterized in that the refractive index difference between the transparent resin and the fiber fabric is 0.01 or below, the fiber fabric is constituted of warp and weft yarns comprising monofilament bundled yarn and the rod-like substance has refractive index anisotropy. The rod-like substance is dispersed in a state that the long axis direction of the rod-like substance almost coincides with the yarn fiber axis direction of the warp or weft yarn and the difference between the refractive index of the fiber fabric and that of either one of the refractive indexes in the long and short axis directions of the rod-like substance is 0.01 or below. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical resin sheet having a small coefficient of linear expansion and excellent dimensional stability, which is suitable for a display device such as a liquid crystal display device, an organic EL display device, and electronic paper.

  At present, liquid crystal display devices are widely used as display media. The liquid crystal panel has a structure in which a liquid crystal cell is formed by sandwiching liquid crystal between two transparent substrates, and polarizing plates are arranged on both surfaces of the cell. A liquid crystal display device is configured by combining this panel with a driving LSI and a backlight.

  By the way, such a liquid crystal display device does not necessarily have high use efficiency of light emitted from the backlight. This is because 50% of the light emitted from the backlight is theoretically absorbed by the back polarizer. Therefore, a configuration in which a reflective polarizing plate is arranged between the back-side polarizing plate and the backlight in order to increase the utilization efficiency of the backlight in the liquid crystal display device is known and applied to a liquid crystal television or the like.

  The reflective polarizing plate reflects some kinds of polarized light and transmits polarized light having a 90 ° vibration plane different from that. Axes are aligned so that light transmitted through the reflective polarizing plate passes through the back polarizing plate as linearly polarized light. The polarized light reflected by the reflective polarizing plate returns to the backlight side, is reflected by the reflecting plate, and is reused, thereby increasing the utilization efficiency of the light emitted from the backlight.

  As such a reflective polarizing plate, for example, a reflective polarizing plate in which a cholesteric liquid crystal layer and a quarter-wave plate described in Patent Literature 1 and Patent Literature 2 are combined, and described in Patent Literature 3 and Patent Literature 4. A reflective polarizing plate composed of a multi-layered film of a birefringent layer and an isotropic layer is known.

  A reflective polarizing plate combining a cholesteric liquid crystal layer and a quarter wave plate transmits right (or left) circularly polarized light having a wavelength corresponding to the helical pitch of the cholesteric liquid crystal and converts it into linearly polarized light with the quarter wave plate. Reflects left (or right) circularly polarized light. However, with this reflective polarizing plate, it is difficult to convert right (or left) circularly polarized light transmitted through the cholesteric liquid crystal layer to linearly polarized light with a single quarter-wave plate over the entire visible light range (Patent Literature). 2, paragraph 0007). In order to solve this difficulty, it is necessary to laminate and form a plurality of quarter-wave plates. When a plurality of quarter-wave plates are stacked, the manufacturing process becomes complicated, and there is a problem that peeling may occur between the quarter-wave plates.

  In a reflective polarizing plate composed of a multi-layered film of a birefringent layer and an isotropic layer, it is necessary to form several hundreds of alternately laminated structures, and a large-scale manufacturing facility is required. In addition, since different materials are laminated, there is a problem that peeling is likely to occur between layers.

In addition, when an optical member such as a polarizing plate, a reflective polarizing plate, and a wave plate each having a thickness of 0.1 to 0.2 mm is further laminated on a transparent substrate that holds the liquid crystal, As the thickness of the liquid crystal panel increases, the characteristics of the liquid crystal panel, which is a thin display element, are impaired. Therefore, thinning of each member, reduction in the number of members, and integration of functions of each member are required, and heat resistance and dimensional stability are also required for the member including the substrate of the display element.
JP-A-6-281814 JP-A-8-271731 Japanese National Patent Publication No. 9-506837 Japanese National Patent Publication No. 10-511322

  An object of the present invention is to provide an optical resin sheet having a small linear expansion coefficient and excellent dimensional stability, which is suitable for a display device such as a liquid crystal display device, an organic EL display device, and electronic paper.

The present invention is as follows.
(1) An optical resin sheet containing a transparent resin, a fiber cloth, and a rod-like substance, wherein a refractive index difference between the transparent resin and the fiber cloth is 0.01 or less, and the fiber cloth bundles single yarns. It is composed of warp yarns and weft yarns, and the rod-like material has refractive index anisotropy, and the rod-like material has substantially the same long axis direction of the rod-like material as the yarn fiber axis direction of the warp yarn or the weft yarn. An optical resin sheet that is dispersed in a state where the difference between the refractive index of the fiber cloth and the refractive index of one of the major axis direction and the minor axis direction of the rod-shaped substance is 0.01 or less.
(2) The transparent resin is obtained by curing a resin composition containing a cationically polymerizable component, and the cationically polymerizable component is a compound having one or more epoxy groups, an oxetanyl group. The optical resin sheet according to (1), comprising a compound having a compound having a vinyl ether group.
(3) The optical resin sheet according to (1), wherein the transparent resin is obtained by curing a resin composition containing an alicyclic epoxy resin represented by the chemical formula (1) as a main component.

(4) The optical resin sheet according to any one of (1) to (3), wherein the fiber cloth is a glass fiber woven cloth.
(5) The optical resin sheet according to any one of (1) to (4), wherein the fiber cloth has a refractive index of 1.45 to 1.60.
(6) The optical resin sheet according to any one of (1) to (5), wherein the rod-like substance is mineral or ceramic.
(7) The optical resin sheet according to any one of (1) to (5), wherein the rod-shaped substance is strontium carbonate.
(8) The optical resin sheet according to any one of (1) to (7), wherein an average linear expansion coefficient at 30 to 150 ° C. is 40 ppm or less.
(9) A scattering reflection type polarizing sheet using the optical resin sheet according to any one of (1) to (8).
(10) A laminated optical sheet obtained by laminating an absorption type polarizing plate on one side of the scattering reflection type polarizing sheet according to (9) so that both absorption axes coincide with each other.
(11) A laminated optical sheet in which a retardation layer is further laminated on the surface of the laminated optical sheet according to (10), on which the absorption polarizing plate is laminated.
(12) A laminated optical sheet in which a retardation layer is laminated on one side of the optical resin sheet according to any one of (1) to (8).
(13) A plastic substrate for liquid crystal display using the laminated optical sheet according to any one of (9) to (11).
(14) A plastic substrate for organic EL using the laminated optical sheet according to (12).
(15) A plastic substrate for electronic paper using the laminated optical sheet according to (12).

  The optical resin sheet of the present invention has a polarizing function that has a small linear expansion coefficient and excellent dimensional stability, and has a thinner display element, improved luminance of a liquid crystal display device, and visual recognition of an organic EL display element and electronic paper. It can be applied as a useful optical resin sheet that contributes to the improvement of properties.

Hereinafter, the present invention will be described in detail.
The present invention is an optical resin sheet containing a transparent resin, a fiber cloth, and a rod-shaped substance, wherein the refractive index difference between the transparent resin and the fiber cloth is 0.01 or less, and the fiber cloth bundles single yarns. The rod-shaped material has refractive index anisotropy, and the rod-shaped material has a major axis direction of the rod-shaped material and a yarn fiber axis direction of the warp yarn or the weft yarn. An optical resin sheet which is dispersed in a matched state and has a difference between the refractive index of the fiber cloth and the refractive index of either the major axis direction or the minor axis direction of the rod-shaped substance of 0.01 or less It is.
The rod-shaped substance can be, for example, a needle crystal or a whisker. That is, since the difference in refractive index between the transparent resin and the fiber cloth is small, it is an optically transparent composite substrate. By arranging the rod-shaped substances in the warp or weft direction of the fiber cloth, the rod-shaped substances are transparent in the composite substrate. A dispersed state uniaxially oriented in the vertical direction or the horizontal direction can be formed. At this time, since the refractive index of the fiber cloth and the refractive index in the major axis or minor axis direction of the rod-shaped substance are substantially the same, the polarization in the axial direction is substantially the same as the refractive index of the fiber cloth and the refractive index of the rod-shaped substance. Light is transmitted, and axially polarized light having different refractive indexes is scattered. By combining the positive and negative refractive index anisotropy and the uniaxial orientation direction of the rod-like material according to the purpose, it is possible to obtain a scattering reflection type polarizing sheet in which the transmission polarization axis direction can be selected. Table 1 shows examples of combinations. The refractive index in the major axis direction of the rod-shaped substance is n1, the refractive index in the minor axis direction is n2, and the refractive index of the fiber cloth is nf.

  Here, the refractive index anisotropy being positive means that the refractive index in the major axis direction of the crystal is larger than the refractive index in the minor axis direction, and the positive birefringence is the major axis direction. A state in which the refractive index is larger than the refractive index in the minor axis direction. Conversely, negative refractive index anisotropy means that the refractive index in the major axis direction of the crystal is smaller than the refractive index in the minor axis direction, and negative birefringence means refraction in the major axis direction. It means a state where the refractive index is smaller than the refractive index in the minor axis direction. The refractive index anisotropy of the rod-like inorganic material will be described. When the refractive index in the major axis direction of the crystal is larger than the refractive index in the minor axis direction, the refractive index anisotropy is positive. Conversely, when the refractive index in the major axis direction of the crystal is smaller than the refractive index in the minor axis direction, the refractive index anisotropy is negative.

  The rod-shaped substance used in the present invention has a refractive index anisotropy, and any organic compound or inorganic compound can be selected as long as it has a shape anisotropy. These crystals and ceramics are preferred. When the birefringence is large, the difference in refractive index with the transparent composite substrate can be increased, so that the transmission and scattering characteristics of polarized light can be enhanced, so that the polarization characteristics of the optical resin sheet can be enhanced. Examples of the inorganic compound having positive birefringence include rutile, aluminum borate, hydrous calcium silicate, and basic magnesium sulfate. Examples of inorganic compounds having negative birefringence include calcium carbonate (calcite), magnesite, smithsonite, and strontium carbonate.

  The rod-shaped substance has an elongated structure, and the aspect ratio of the major axis length to the minor axis diameter is preferably 2 or more, and more preferably 10 or more. If it is an inorganic compound, a needle-like crystal or a whisker (needle-like body) is preferable. Further, it is preferably larger than the minor axis diameter of the rod-like substance and the wavelength of visible light, more preferably 0.5 μm or more and 1 μm or more. Further, the difference in refractive index between the major axis direction and the minor axis direction of the rod-shaped substance is preferably 0.05 or more, and this refractive index difference is more preferably 0.1 or more.

  As the transparent resin used in the optical resin sheet of the present invention, various resins can be used and are not particularly limited, but are obtained by curing a resin composition containing a cationically polymerizable component. The component capable of cationic polymerization includes, for example, a compound having an epoxy group, a compound having an oxetanyl group, or a vinyl ether group.

  Examples of the compound having an epoxy group include a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, a bisphenol S type epoxy resin, or a hydrogenated product thereof, an epoxy resin having a dicyclopentadiene skeleton, and a triglycidyl isocyanurate skeleton. Examples of epoxy resins, epoxy resins having a cardo skeleton, and alicyclic epoxy resins include 3,4-epoxycyclohexylmethyl 3 ′, 4′-epoxycyclohexylcarboxylate, 1,8,9, diepoxy limonene, dicyclopentadiene diene. 3,4-epoxycyclohexylmethanol and 3,4-epoxycyclohexylcarboxylic acid are attached to both ends of oxide, cyclooctene dioxide, acetal diepoxyside, and ε-caprolactone oligomer, respectively. Examples include ter-bonded ones, epoxidized hexahydrobenzyl alcohol, alicyclic polyfunctional epoxy resins, alicyclic epoxy resins having a hydrogenated biphenyl skeleton, alicyclic epoxy resins having a hydrogenated bisphenol A skeleton, and the like. It is done.

Examples of the compound having an oxetanyl group include 1,4-bis {[(3-ethyl-3-oxetanyl) methoxy] methyl} benzene (arone oxetane OXT-121 (XDO)), di [2- (3-oxetanyl) butyl. ] Ether (Aron oxetane OXT-221 (DOX)), 1,4-bis [(3-ethyloxetane-3-yl) methoxy] benzene (HQOX), 1,3-bis [(3-ethyloxetane-3- Yl) methoxy] benzene (RSOX), 1,2-bis [(3-ethyloxetane-3-yl) methoxy] benzene (CTOX), 4,4′-bis [(3-ethyloxetane-3-yl) methoxy ] Biphenyl (4,4'-BPOX), 2,2'-bis [(3-ethyl-3-oxetanyl) methoxy] biphenyl (2,2'-BPOX) ), 3,3 ′, 5,5′-tetramethyl [4,4′-bis (3-ethyloxetane-3-yl) methoxy] biphenyl (TM-BPOX), 2,7-bis [(3-ethyl Oxetane-3-yl) methoxy] naphthalene (2,7-NpDOX), 1,6-bis [(3-ethyloxetane-3-yl) methoxy] -2,2,3,3,4,4,5,5 5-octafluorohexane (OFH-DOX), 3 (4), 8 (9) -bis [(1-ethyl-3-oxetanyl) methoxymethyl] -tricyclo [5.2.1.0 ^2.6 ] decane, , 2-bis [2-{(1-ethyl-3-oxetanyl) methoxy} ethylthio] ethane, 4,4′-bis [(1-ethyl-3-oxetanyl) methyl] thiodibenzenethioether, 2,3- Bis [(3-ethyloxetane- -Yl) methoxymethyl] norbornane (NDMOX), 2-ethyl-2-[(3-ethyloxetane-3-yl) methoxymethyl] -1,3-O-bis [(1-ethyl-3-oxetanyl) methyl ] -Propane-1,3-diol (TMPTOX), 2,2-dimethyl-1,3-O-bis [(3-ethyloxetane-3-yl) methyl] -propane-1,3-diol (NPGOX) 2-butyl-2-ethyl-1,3-O-bis [(3-ethyloxetane-3-yl) methyl] -propane-1,3-diol, 1,4-O-bis [(3-ethyl Oxetane-3-yl) methyl] -butane-1,4-diol, 2,4,6-O-tris [(3-ethyloxetane-3-yl) methyl] cyanuric acid, bisphenol A and 3-ethyl-3 - Etherified product of romethyloxetane (abbreviated as OXC) (BisAOX), etherified product of bisphenol F and OXC (BisFOX), etherified product of phenol novolac and OXC (PNOX), etherified product of cresol novolac and OXC (CNOX), oxetanylsil Sesquioxane (OX-SQ), 3-ethyl-3-hydroxymethyloxetane silicon alkoxide (OX-SC) 3-ethyl-3- (2-ethylhexyloxymethyl) oxetane (Aron oxetane OXT-212 ( EHOX)), 3-ethyl-3- (dodecyloxymethyl) oxetane (OXR-12), 3-ethyl-3- (octadecyloxymethyl) oxetane (OXR-18), 3-ethyl-3- (phenoxy) Methyl) oxetane (Aron oxetane OXT-211 (POX)), 3-ethyl-3-hydroxymethyloxetane (OXA), 3- (cyclohexyloxy) methyl-3-ethyloxetane (CHOX) and the like. Here, the parentheses are product names or abbreviations of Toagosei Co., Ltd.

  The compound having a vinyl ether group is not particularly limited, but 2-hydroxyethyl vinyl ether, diethylene glycol monovinyl ether, 4-hydroxybutyl vinyl ether, diethylene glycol vinyl ether, triethylene glycol divinyl ether, cyclohexane dimethanol divinyl ether, cyclohexane dimethanol monovinyl ether, Examples thereof include tricyclodecane vinyl ether, cyclohexyl vinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether, pentaerythritol type tetravinyl ether, and the like.

  Among these, it is particularly preferable that the resin composition is obtained by curing a resin composition containing the alicyclic epoxy resin represented by the chemical formula (1) as a main component. This is because the linear expansion coefficient (αm) of the cured product to which the chemical formula (1) is applied is small, so that the linear expansion coefficient when combined with the fiber cloth can be reduced.

  In order to cure these resins and compounds, in the case of curing alone, they can be cured using a cationic catalyst or an anionic catalyst, and can also be cured using various curing agents. For example, in the case of an epoxy resin, it can be cured using an acid anhydride or an aliphatic amine.

  Examples of the cationic curing catalyst include those that release a substance that initiates cationic polymerization upon heating (for example, an onium salt cationic thermal cationic curing catalyst or an aluminum chelate cationic curing catalyst), and cationic polymerization using active energy rays. (For example, an onium salt-based cationic curing catalyst) that releases a substance that initiates the reaction. Among these, a thermal cationic curing catalyst is preferable. Thereby, the hardened | cured material which is more excellent in heat resistance can be obtained.

  Examples of the thermal cationic curing catalyst include aromatic sulfonium salts, aromatic iodonium salts, ammonium salts, aluminum chelates, and boron trifluoride amine complexes. Specific examples of aromatic sulfonium salts include hexafluoroantimonate salts such as SI-60L, SI-80L, SI-100L manufactured by Sanshin Chemical Industries, and SP-66 and SP-77 manufactured by Asahi Denka Kogyo. Examples of the aluminum chelate include ethyl acetoacetate aluminum diisopropylate and aluminum tris (ethyl acetoacetate). Examples of the boron trifluoride amine complex include boron trifluoride monoethylamine complex, boron trifluoride imidazole complex, and trifluoride. Examples thereof include boron bromide piperidine complexes.

  The content of the cationic catalyst is not particularly limited. For example, when the epoxy resin represented by the formula (1) is used, the content is preferably 0.1 to 3 parts by weight with respect to 100 parts by weight of the epoxy resin. 0.5 to 1.5 parts by weight is particularly preferable. If the content is less than the lower limit, the curability may be lowered, and if the content exceeds the upper limit, the resin sheet may be brittle. If necessary, a sensitizer and an acid proliferating agent can be used together to accelerate the curing reaction.

  In order to improve the transparency by combining the refractive index of the fiber cloth and the resin in the optical resin sheet of the present invention, a refractive index adjusting component such as resin, organic fine particles and inorganic fine particles can be added to the transparent resin. . If the refractive index of the main component resin is higher than the refractive index of the fiber cloth used, the refractive index adjusting component can be added with a component lower than the refractive index of the fiber cloth, and conversely, the refractive index of the main component. Is lower than the fiber cloth used, a component higher than the refractive index of the fiber cloth can be added.

  When a resin is added as a refractive index adjusting component, it is preferable to add a cationically polymerizable component that is a compound having a functional group that undergoes a crosslinking reaction with the main component resin. The cationically polymerizable component is preferably a compound having one or more epoxy groups, a compound having an oxetanyl group, or a compound having a vinyl ether group.

  For example, an alicyclic epoxy monomer having a silsesqui skeleton, an oxetane monomer having a silsesqui skeleton, an oligomer having a silicate structure (manufactured by Konishi Chemical: PSQ resin, manufactured by Toa Gosei: oxetanyl silsesquioxane, oxetanyl silicate), β- (3 , 4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltriethoxysilane and the like. In particular, oxetanyl silicate represented by the chemical formula (2) is preferable.

n is an integer from 1 to 5

When inorganic fine particles are added as the refractive index adjusting component, for example, nanoparticles, glass beads and the like can be mentioned, and particles having an average dispersed particle diameter of 100 nm or less are preferable.
Specific examples include silica fine particles having a silicate structure, titanium oxide fine particles, zirconia oxide fine particles, and alumina fine particles. These particles can be appropriately used for adjusting the refractive index.

For example, when the refractive index of the resin as the main component is higher than the refractive index of the fiber cloth, silica fine particles having a lower refractive index than the fiber cloth are preferable. Thereby, high transparency can be obtained without deteriorating the physical properties of the cured product such as heat resistance and linear expansion coefficient.
Of the same silica fine particles, silica fine particles that have been surface-treated are more preferred. This is because active hydrogen (silanol group) that promotes cationic polymerization exists on the surface of the fine particles, and when there is no surface treatment, the curing reaction proceeds and the storage stability is low.

  Although the refractive index of the fiber cloth used for this invention is not specifically limited, 1.4-1.6 are preferable and especially 1.5-1.55 are preferable. This is because the closer the Abbe number of the transparent resin and the Abbe number of the fiber cloth, the higher the refractive index in a wide wavelength region, and the higher the light transmittance in a wide range.

  Examples of the fiber cloth used in the present invention include fiber cloths such as glass fiber and resin fiber. Among them, a woven cloth of glass fiber is preferable because the effect of reducing the linear expansion coefficient is high, and glass cloth is most preferable.

  The types of glass include E glass, C glass, A glass, S glass, T glass, D glass, NE glass, quartz, low dielectric constant glass, and high dielectric constant glass, among which ionic impurities such as alkali metals E glass, S glass, and T glass NE glass, which are easy to obtain, are few.

  The blending amount of the fiber cloth is preferably 1 to 90% by weight, more preferably 10 to 80% by weight, and still more preferably 30 to 70% by weight with respect to the optical resin sheet. If the blending amount of the fiber cloth is within this range, molding is easy, and the effect of lowering linear expansion due to compounding is recognized.

Although the example of the method of orientating a rod-shaped substance to the yarn fiber axis | shaft of the warp or weft of the fiber cloth of this invention is demonstrated, this invention is not limited to the following examples of an orientation process, unless the summary is exceeded. Hereinafter, the manufacturing process of the fiber cloth will be described as an example.
The process of making the fiber cloth includes: (a) a raw material mixing and melting process; (b) a process for producing a single yarn by spinning the melted raw material; (c) a yarn production process by single yarn twisting; (d) a fiber weaving by a loom This can be broadly divided into the fabric production process. Therefore, it is preferable to combine the rod-like substance at the stage of the yarn production process from the single yarn. It is possible to fabricate a fiber woven fabric in which the rod-like material is dispersed in the warp or weft by compounding the rod-like material at the stage of the yarn in which the single yarn is bundled, and then weaving the yarn in which the rod-like material is compounded as warp or weft. it can. When producing a fiber cloth with a loom, warp yarns are woven while maintaining a constant tension rather than weft yarns. Therefore, in order to orient the rod-like material more statistically, it is preferable to disperse the rod-like material in the warp yarn.

  In the present invention, there is a method of continuously immersing a single yarn or a yarn bundled with a single yarn in a solution in which the rod-like material is dispersed as a method of combining the rod-like material with a yarn bundled with a single yarn. As the dispersion liquid for dispersing the rod-shaped substance, it is preferable to use water or water and alcohol in which starch, polyvinyl alcohol, or a coupling agent is added alone or in combination as a additive and dissolved. An addition system in which a coupling agent is used alone or in combination with a coupling agent and starch or polyvinyl alcohol is more preferable. Starch, polyvinyl alcohol, and a coupling agent have an action of adsorbing a rod-like substance on the surface of the single yarn and an action of converging the single yarns. In order to improve the orientation of the rod-shaped substance on the yarn fiber axis, it is possible to appropriately select to vibrate the solution in which the rod-shaped substance is dispersed with ultrasonic waves or to control the speed at which the yarn is continuously processed. It is preferable to fabricate a fiber woven fabric using a yarn in which rod-shaped substances are combined, and then to fire and open the fiber woven fabric. As the opening method, opening by a hydraulic jet or opening by a rolling roll can be applied. Since the additive is removed by firing, the amount of the additive having a refractive index different from that of the fiber cloth and the rod-like substance can be reduced. Moreover, the filling property of transparent resin improves by opening. Furthermore, since shear shear stress is applied between the single yarns, the orientation of the rod-like substance can be improved.

  There is no limitation on the molding method of the optical resin sheet of the present invention. For example, an uncured resin composition or a varnish obtained by dissolving a resin composition in a solvent is impregnated into a fiber cloth and then crosslinked to form a sheet or the like. Is mentioned.

  The thickness of the optical resin sheet of the present invention is preferably 50 to 2000 μm, more preferably 50 to 1000 μm, and most preferably 50 to 200 μm.

  The optical resin sheet of the present invention preferably has an average linear expansion coefficient at 30 ° C. to 150 ° C. of 40 ppm or less, more preferably 30 ppm or less, and most preferably 20 ppm or less.

  The optical resin sheet of the present invention can be appropriately laminated with an optical functional sheet such as an absorption polarizing plate or a retardation plate depending on the display element to be applied. Examples of the laminating method include laminating with an adhesive and a method of directly forming a functional layer on an optical resin sheet. For example, when producing a thin liquid crystal panel, an optical resin sheet on which a transparent electrode / liquid crystal alignment film is formed is used, and the optical resin sheet / twist nematic liquid crystal / opposing transparent substrate / absorptive polarizing plate (polarized light) from the backlight side. The axis of the optical resin sheet is perpendicular to the polarization axis of the optical resin sheet. When manufacturing a liquid crystal panel with high definition and high light utilization efficiency, use a laminated optical sheet in which an optical resin sheet / absorptive polarizing plate / retardation plate is laminated, and laminated optical sheet / liquid crystal / opposed transparent from the backlight side. The layer structure of the substrate / retardation plate / absorption type polarizing plate (expressed by omitting the transparent electrode and alignment film) is raised. In the case of producing an organic EL panel with reduced external light reflection, a laminated optical sheet in which a slow axis of a quarter wavelength plate is laminated in a 45 ° azimuth direction from the polarization transmission axis of the optical resin sheet is used. A configuration in which an EL element is formed on the four-wavelength plate side is raised.

EXAMPLES Hereinafter, although the content of this invention is demonstrated in detail by an Example, this invention is not limited to the following examples, unless the summary is exceeded. Evaluation was performed by the following method.
(A) Average linear expansion coefficient Using a TMA / SS6000 type thermal stress strain measuring device manufactured by SEIKO ELECTRONICS CO., LTD., The temperature was increased at a rate of 5 ° C. per minute in a nitrogen atmosphere. The load was set to 5 g, the measurement was performed in the tensile mode, and the average coefficient of linear expansion from 30 ° C to 150 ° C was calculated.
(B) Refractive index Only the resin composition used for the optical resin sheet was cured under the same curing conditions as the optical resin sheet of the example, and the refractive index at a wavelength of 598 nm was measured with an Abbe refractometer.
(C) Polarization degree, single transmittance The single transmittance was measured using a spectrophotometer U3200 (manufactured by Shimadzu Corporation). The polarization degree was parallel polarized light transmittance (T1) and vertical polarized light transmittance (T2) at a wavelength of 550 nm. Was calculated and the degree of polarization = ((T1−T2) / (T1 + T2)).
(D) Heat resistance The maximum value of tanδ at 1 Hz was defined as the glass transition temperature (Tg) using a DNS210 type dynamic viscoelasticity measuring device manufactured by SEIKO ELECTRONICS.

Example 1
A 6 μm diameter T glass single yarn (refractive index 1.523) was prepared by adding polyvinyl alcohol and a coupling agent to water / ethanol to 100 parts by weight of a dispersion solvent, and a strontium carbonate needle crystal having a fiber length of 30 μm and a fiber diameter of 1 μm. (Long axis refractive index = 1.520, short axis refractive index = 1.668, Δn = 0.148) A strontium carbonate composite single yarn was prepared by immersing in a dispersion in which 15 parts by weight were dispersed. Next, 200 composite single yarns were bundled to produce a crystal dispersion yarn. Further, 200 T glass single yarns were bundled to produce a T glass yarn. Subsequently, a T-glass cloth was produced at a pitch of 60 warp yarns / 25 mm × 58 weft yarns / 25 mm with a crystal-dispersed yarn as warp and a crystal undispersed T-glass yarn as weft. The produced T glass cloth was baked at 400 ° C., followed by fiber opening treatment by roll pressurization to obtain a 90 μm-thick strontium carbonate dispersed T glass cloth.
Next, 100 parts by weight of a hydrogenated biphenyl type alicyclic epoxy resin (Daicel Chemical Industrial, E-BP) having a structure of chemical formula (1) on the produced T glass cloth, an aromatic sulfonium-based thermal cation catalyst (Sanshin) Chemical resin SI-100L) was impregnated with a resin composition mixed with 1 part by weight and defoamed. This resin-impregnated glass cloth was sandwiched between release-treated glass substrates, heated at 80 ° C. for 2 hours, and further heated at 250 ° C. for 2 hours to obtain an optical resin sheet having a thickness of 100 μm.
The evaluation results of the obtained optical resin sheet are shown below.
Refractive index after curing of resin composition: 1.524
Average coefficient of linear expansion: 13 ppm
Heat resistance:> 250 ° C
Single transmittance: 40%
Polarization degree: 89%
The transmission polarization axis was the warp direction.

Claims (15)

An optical resin sheet containing a transparent resin, a fiber cloth, and a rod-like substance, wherein a refractive index difference between the transparent resin and the fiber cloth is 0.01 or less, and the warp of a yarn in which the fiber cloth is a bundle of single yarns And the rod-shaped substance has refractive index anisotropy, and the rod-shaped substance is in a state where the major axis direction of the rod-shaped substance and the yarn fiber axis direction of the warp yarn or the weft yarn substantially coincide with each other. An optical resin sheet which is dispersed and has a difference between the refractive index of the fiber cloth and the refractive index of one of the major axis direction and the minor axis direction of the rod-shaped substance of 0.01 or less. The transparent resin is obtained by curing a resin composition containing a cationically polymerizable component, and the cationically polymerizable component is a compound having one or more epoxy groups, a compound having an oxetanyl group, Or the optical resin sheet of Claim 1 containing the compound which has a vinyl ether group. The optical resin sheet according to claim 1, wherein the transparent resin is obtained by curing a resin composition containing an alicyclic epoxy resin represented by the chemical formula (1) as a main component.
The optical resin sheet according to any one of claims 1 to 3, wherein the fiber cloth is a glass fiber woven cloth. The optical resin sheet according to any one of claims 1 to 4, wherein the fiber cloth has a refractive index of 1.45 to 1.60. The optical resin sheet according to any one of claims 1 to 5, wherein the rod-shaped substance is a mineral or a ceramic. The optical resin sheet according to claim 1, wherein the rod-shaped substance is strontium carbonate. The optical resin sheet according to any one of claims 1 to 7, wherein an average linear expansion coefficient at 30 to 150 ° C is 40 ppm or less. A scattering reflection type polarizing sheet using the optical resin sheet according to claim 1. A laminated optical sheet in which an absorption polarizing plate is laminated on one side of the scattering reflection type polarizing sheet according to claim 9 so that both absorption axes coincide with each other. The laminated optical sheet which laminated | stacked the phase difference layer further on the surface which laminated | stacked the absorption-type polarizing plate of the laminated optical sheet of Claim 10. A laminated optical sheet in which a retardation layer is laminated on one side of the optical resin sheet according to claim 1. A plastic substrate for liquid crystal display using the laminated optical sheet according to claim 9. A plastic substrate for organic EL using the laminated optical sheet according to claim 12. A plastic substrate for electronic paper using the laminated optical sheet according to claim 12.