JP4804595B1 - Production method of transparent composite sheet - Google Patents

Abstract

By compounding the glass cloth, a transparent composite sheet is obtained that not only has a low coefficient of thermal expansion, but also has unevenness reflecting the fiber shape of the glass cloth on the surface.
The transparent composite sheet 1 according to the present invention has first and second surfaces 1a and 1b facing each other. The transparent composite sheet 1 which concerns on this invention contains transparent resin hardened | cured material and the glass cloth embedded in this transparent resin hardened | cured material. In the transparent composite sheet 1 according to the present invention, the amplitude of the surface irregularities that coincides with the warp or weft cycle of the glass cloth on the surface of the sheet is 0.5 to 5 μm on the first surface 1a, and the second surface 1b. Is 0.4 μm or less.
[Selection] Figure 1

Description

The present invention relates to a method for producing a transparent composite sheet used for an application requiring transparency, such as a display element substrate, and more specifically, a transparent resin cured product and embedded in the transparent resin cured product. about the production how of transparency composite sheet you containing a glass cloth.

  Glass substrates are widely used for display element substrates such as liquid crystal display elements or organic EL display elements, and solar cell substrates. The glass substrate has problems that it is easily broken, has low bendability, and cannot be reduced in weight. For this reason, in recent years, it has been studied to use a plastic substrate instead of a glass substrate.

  However, the thermal expansion coefficient of a conventional plastic substrate may be about 10 to 20 times larger than the thermal expansion coefficient of glass. In display elements and solar cells, a semiconductor layer or a conductive layer is often made of an inorganic material. Accordingly, when a display element or a solar cell is manufactured using a plastic substrate having a large thermal expansion coefficient, the thermal expansion coefficient between the plastic substrate and the inorganic material layer in the heating and cooling process for forming a semiconductor layer or a conductive layer, etc. Depending on the difference, cracks may occur in the inorganic material layer. Furthermore, when a display element is manufactured using a plastic substrate having a large thermal expansion coefficient, the dimensions of the plastic substrate greatly change due to temperature variations in the manufacturing process. Therefore, mask alignment in the photolithographic process may be difficult.

  In order to reduce the thermal expansion coefficient, for example, Patent Document 1 below discloses a plastic substrate obtained by applying a resin composition to glass cloth, impregnating it, and drying it.

JP 2004-151291 A

  In the plastic substrate described in Patent Document 1, when the resin composition is cured by impregnating the glass cloth with the resin composition and drying, the fiber of the glass cloth is formed on the surface of the plastic substrate by curing shrinkage of the resin composition. Unevenness reflecting the shape is likely to occur. For this reason, there is a problem that a transmission image viewed through the plastic substrate is distorted.

  Moreover, when the unevenness | corrugation reflecting the fiber shape of the glass cloth arises on the surface of a plastic substrate, when this plastic substrate is used as a substrate for liquid crystal display elements, the thickness of the liquid crystal encapsulating layer becomes non-uniform. As a result, the display image is uneven, and so-called cell gap unevenness occurs.

An object of the present invention not only can reduce the thermal expansion coefficient by compounding the glass cloth, the glass cloth fiber shape reflecting the uneven of transparency composite sheet Ru can be hardly generated on the surface It is to provide a manufacturing how.

  The transparent composite sheet according to the present invention has first and second surfaces facing each other. The transparent composite sheet according to the present invention includes a transparent resin cured product and a glass cloth embedded in the transparent resin cured product, and the amplitude of surface irregularities that matches the warp or weft cycle of the glass cloth on the sheet surface. Is 0.5-5 μm on the first surface and 0.4 μm or less on the second surface.

  The laminated sheet provided in a specific aspect of the present invention includes the transparent composite sheet of the present invention, a polarizing plate laminated on the first surface of the transparent composite sheet, and the polarizing plate as the transparent composite sheet. An adhesive layer disposed between the polarizing plate and the first surface of the transparent composite sheet so as to be bonded together;

  A liquid crystal display element according to the present invention includes a first substrate, a second substrate opposed to the first substrate with a gap, and a liquid crystal layer disposed between the first and second substrates. Is provided. At least one of the first and second substrates is bonded to the transparent composite sheet, the polarizing plate laminated on the first surface of the transparent composite sheet, and the polarizing plate to the transparent composite sheet. It is a laminated sheet provided with the adhesive layer provided between the 1st surface of the said transparent composite sheet, and the said polarizing plate.

  The method for producing a transparent composite sheet according to the present invention comprises a step of preparing a glass cloth impregnated with a curable transparent resin having transparency after curing, and at least one selected from the group consisting of metal, glass and ceramics A glass cloth impregnated with the curable transparent resin is sandwiched between a rigid body having a material and a flat surface, and a flexible body having a flat surface and softer than the rigid body, And a step of curing the curable transparent resin by at least one of irradiation with light rays. As the flexible body, a resin film is preferably used. In the step of curing the curable transparent resin, it is preferable to irradiate the curable transparent resin with light and to heat the curable transparent resin.

  In the transparent composite sheet of the present invention, since the glass cloth is embedded in the transparent resin cured product, the thermal expansion coefficient can be lowered. Furthermore, in the transparent composite sheet of the present invention, the amplitude of the irregularities on the surface reflecting the fiber shape of the glass cloth is 0.5 to 5 μm on the first surface, and 0.4 μm or less on the second surface, The flatness of the second surface relative to the first surface is enhanced. In the conventional transparent composite sheet in which the glass cloth is embedded, the unevenness of the surface was as large as 0.5 μm or more, reflecting the fiber shape of the glass cloth, whereas in the transparent composite sheet of the present invention, the second The flatness of the surface is effectively enhanced. Therefore, when the transparent composite sheet is used as the liquid crystal element substrate of the liquid crystal display element so that the second surface is positioned on the liquid crystal layer side of the liquid crystal display element, for example, the variation in the cell gap can be reduced.

  Moreover, like the lamination sheet of this invention, a polarizing plate is provided through the adhesive layer on the 1st surface side whose amplitude of surface unevenness reflecting the fiber shape of the glass cloth is relatively large as 0.5 to 5 μm. By sticking together, the unevenness | corrugation of the said surface can be filled with an adhesive layer. Accordingly, it is possible to reduce distortion of a transmission image visually recognized through a substrate that is a laminated sheet using a transparent composite sheet.

  Therefore, by using the laminated sheet having the transparent composite sheet according to the present invention on at least one of the first and second substrates of the liquid crystal display element having the first and second substrates for sealing the liquid crystal, the liquid crystal display element Display quality can be improved.

FIG. 1 is a partially cutaway sectional view schematically showing a transparent composite sheet according to an embodiment of the present invention. FIG. 2 is a partially cutaway cross-sectional view schematically showing a laminated sheet using the transparent composite sheet shown in FIG. FIG. 3 is a partially cutaway sectional view schematically showing an example of use of the transparent composite sheet shown in FIG. FIG. 4 is a partially cutaway sectional view showing a liquid crystal display element using the transparent composite sheet shown in FIG.

  Hereinafter, the present invention will be described in detail.

  The present inventors have intensively studied in order to reduce the distortion of a fluoroscopic image in a display element using a transparent composite sheet in which a glass cloth is embedded in a transparent resin cured product. As a result, when a glass cloth is impregnated with a transparent resin and cured, it is sandwiched so that one surface is in contact with a rigid body such as metal or glass and the other surface is in contact with a flexible body such as a resin film. It has been found that the surface irregularity can be effectively reduced on one surface that is in contact with the rigid body by curing in a stale state. A surface having relatively small irregularities is referred to as a second surface, and a surface opposite to the second surface is referred to as a first surface.

  As described above, in a transparent composite sheet in which a conventional glass cloth is impregnated with a transparent resin, irregularities reflecting the fiber shape of the glass cloth are generated on the surface. On the other hand, when the transparent resin of the glass cloth impregnated with the transparent resin is cured while being in contact with the flat surface of the rigid body as described above, in the second surface, the flat surface of the rigid body is Because it is a rigid body, it is difficult to receive stress due to curing shrinkage. Therefore, the 2nd surface which contacts the flat surface of a rigid body becomes flat rather than the surface of the conventional transparent composite sheet.

  On the other hand, since the first surface is in contact with the flat surface of the member softer than the rigid body, the first surface is affected by the stress at the time of curing shrinkage, and has larger irregularities than the second surface. However, when the transparent composite sheet is used as a substrate of a display element, for example, if the flatness of the second surface is improved, the unevenness on the first surface side can be transmitted by embedding a part of the adhesive layer. Light property can be secured.

  That is, a feature of the present invention is a transparent composite sheet having first and second opposing surfaces, wherein the transparent composite sheet is a transparent resin cured product and a glass cloth embedded in the transparent resin cured product. The amplitude of the surface irregularities reflecting the fiber shape of the glass cloth is relatively large as 0.5 to 5 μm on the first surface, but is very small as 0.4 μm or less on the second surface. It is in. Therefore, when using the transparent composite sheet as a substrate through which the light of the display element is transmitted, by laminating an adhesive or the like on the first surface unevenness, the distortion of the fluoroscopic image is surely reduced. Can do.

  Hereinafter, the detail of each component used in order to obtain the transparent composite sheet which concerns on this invention, and the manufacturing method of a transparent composite sheet are demonstrated.

(Transparent resin cured product (A))
The transparent resin cured product used for the transparent composite sheet (A) according to the present invention is not particularly limited as long as it is a resin cured product having transparency. Examples of the transparent resin (a) that gives such a cured product having transparency include polyester resin, polyethylene resin, poly (meth) acrylic resin, polystyrene resin, polycarbonate resin, polyamide resin, polyacetal resin, polyphenylene sulfide resin, (meta ) Acrylic resin, epoxy resin, phenol resin, vinyl ester resin, polyimide resin, melamine resin, urea resin and the like. As for the said transparent resin (a), only 1 type may be used and 2 or more types may be used together.

  In the present specification, the (meth) acrylic is a general term for acryl and methacryl, and indicates that acryl or methacryl may be used. Similarly, (meth) acrylate may be an acrylate or a methacrylate. (Meth) acryloyl refers to acryloyl and methacryloyl.

  The transparent resin (a) is a curable transparent resin. The transparent resin (a) is preferably a curable resin that is liquid at room temperature (25 ° C.) before curing. If it is liquid at room temperature (25 ° C.), glass cloth can be easily impregnated at room temperature.

  As said transparent resin (a), since it is easy to obtain liquid curable resin at room temperature (25 degreeC) before said hardening, at least selected from the group which consists of a (meth) acrylic resin, an epoxy resin, and an allyl resin One type is preferred. In particular, since both heat resistance and transparency can be improved, a transparent resin having a silsesquioxane skeleton is desirable.

  Examples of the (meth) acrylic resin that is a curable resin that is liquid at room temperature before curing include (meth) acrylic oligomers. The (meth) acrylic resin is crosslinked and cured by at least one of heating and actinic ray irradiation. The cured product of the (meth) acrylic resin has high transparency to visible light. The (meth) acrylic resin preferably has two or more (meth) acryloyl groups in order to obtain a crosslinked structure that increases heat resistance so that a TFT element or a color filter can be formed.

  The (meth) acrylic resin is more preferably a (meth) acrylate having an alicyclic structure or a (meth) acrylate having a triazine ring structure. The (meth) acrylate having the alicyclic structure is preferably norbornane dimethylol di (meth) acrylate or dicyclopentadiene dimethanol di (meth) acrylate. The (meth) acrylate having a triazine ring structure is preferably isocyanuric acid tris (2-acryloyloxyethyl) or ε-caprolactone-modified isocyanuric acid tris (2-acryloyloxyethyl). By using these preferable (meth) acrylate resins, the transparency and heat resistance of the transparent composite sheet can be further enhanced.

  Examples of the method for curing the transparent resin (a) include a method of heating, a method of irradiating actinic rays, and a method of using both heating and irradiation of active energy rays. The transparent resin (a) is preferably a resin that is cured by at least one of heating and irradiation with actinic rays.

  When the transparent resin (a) is a (meth) acrylic resin, a method of irradiating actinic rays is preferable. From the viewpoint of reliably completing the curing reaction and increasing the production efficiency of the transparent composite sheet, it is preferable to irradiate the transparent resin (a) with actinic rays and to heat the transparent resin (a). That is, it is preferable to irradiate the heated transparent resin (a) with actinic rays while the transparent resin (a) is heated. It should be noted that the curing reaction can be completed more reliably by further heating after curing with only actinic rays.

  Even in a transparent resin, the polymerization activation is easy, a rapid reaction with high energy is possible, and it is also widely used as an irradiation source and easy to shield. preferable. Examples of the light source for irradiating the ultraviolet light include a metal halide lamp and a high-pressure mercury lamp.

  In order to crosslink and cure the transparent resin (a) by irradiation with actinic rays, it is preferable to use a transparent resin composition containing the transparent resin (a) and a photopolymerization initiator. Hereinafter, a composition containing the transparent resin (a) and other components such as a photopolymerization initiator is referred to as a transparent resin composition. When the transparent resin (a) is the (meth) acrylic resin, a photopolymerization initiator that generates radicals is suitably used as the photopolymerization initiator.

  The photopolymerization initiator is not particularly limited. For example, benzophenone, N, N′-tetraethyl-4,4′-diaminobenzophenone, 4-methoxy-4′-dimethylaminobenzophenone, 2,2-diethoxyacetophenone, benzoin , Benzoin methyl ether, benzoin propyl ether, benzoin isobutyl ether, benzyldimethyl ketal, α-hydroxyisobutylphenone, thioxanthone, 2-chlorothioxanthone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4- (methylthio) phenyl ] -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1, 2-dimethylamino-2- (4-methyl-benzyl) -1 − ( -Morpholin-4-yl-phenyl) -butan-1-one, 2,6-dimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, t-butylanthraquinone, 1-chloroanthraquinone, 2 , 3-dichloroanthraquinone, 3-chloro-2-methylanthraquinone, 2-ethylanthraquinone, 1,4-naphthoquinone, 9,10-phenanthraquinone, 1,2-benzoanthraquinone, 1,4-dimethylanthraquinone, 2 -Phenylanthraquinone, 2- (o-chlorophenyl) -4,5-diphenylimidazole dimer, 2-mercaptobenzothiazole, 2-mercaptobenzoxazole, and 4- (p-methoxyphenyl) -2,6-di- (Trichloromethyl) -s -Triazine etc. are mentioned. As for the said photoinitiator, only 1 type may be used and 2 or more types may be used together.

  The preferable lower limit of the content of the photopolymerization initiator is 0.01 parts by weight, the more preferable lower limit is 0.1 parts by weight, the preferable upper limit is 2 parts by weight, and the more preferable upper limit with respect to 100 parts by weight of the transparent resin (a). Is 1 part by weight. As the content of the photopolymerization initiator increases, the curing of the transparent resin (a) surely and rapidly proceeds. In particular, when the content of the photopolymerization initiator is greater than the preferable lower limit, the transparent resin can be sufficiently cured. When the content of the photopolymerization initiator is not less than the preferable upper limit, the curing reaction proceeds rapidly, and problems such as cracking during curing and coloring of the transparent resin cured product are likely to occur.

  The transparent resin (a) may be crosslinked and cured by at least one of heating and irradiation with actinic rays, and then heat treatment may be performed at a higher temperature. By heat treatment, the cross-linking reaction can be further advanced, the chemical resistance and the like of the transparent composite sheet can be improved, and the characteristics such as the linear expansion coefficient can be stabilized. The heat treatment conditions are preferably a temperature of 150 to 250 ° C. and a condition of 1 to 24 hours in a nitrogen atmosphere or in a vacuum state.

  An epoxy resin may be used as the transparent resin (a). As this epoxy resin, a conventionally well-known epoxy resin can be used, for example. The epoxy resin is not particularly limited. Examples of the epoxy resin include epoxy resins such as bisphenol A type, bisphenol F type and bisphenol S type, novolac type epoxy resins such as phenol novolak type and cresol novolak type, nitrogen containing triglycidyl isocyanurate type and hydantoin type. Cyclic epoxy resin, alicyclic epoxy resin, aliphatic epoxy resin, naphthalene epoxy resin, glycidyl ether epoxy resin, biphenyl epoxy resin, dicyclopentadiene dicyclo epoxy resin, ester epoxy resin, And ether ester type epoxy resins. A modified product of these epoxy resins may be used. From the viewpoint of preventing discoloration of the transparent composite sheet, the epoxy resin is selected from the group consisting of a bisphenol A type epoxy resin, an alicyclic epoxy resin, a triglycidyl isocyanurate type epoxy resin, and a dicyclopentadiene type epoxy resin. At least one kind is preferred. Moreover, since both heat resistance and transparency can be improved, an epoxy resin having a silsesquioxane skeleton may be used. As for the said epoxy resin, only 1 type may be used and 2 or more types may be used together.

  In order to cure the transparent resin (a), the transparent resin composition may contain a curing agent. In particular, when the transparent resin (a) is an epoxy resin, the transparent resin composition preferably contains a curing agent. Although it does not specifically limit as said hardening | curing agent, An organic acid compound, an amine compound, an acid anhydride compound, etc. are mentioned. As for a hardening | curing agent, only 1 type may be used and 2 or more types may be used together. The transparent resin composition preferably contains at least one of a photopolymerization initiator and a curing agent.

  Examples of the organic acid compound include tetrahydrophthalic acid, methyltetrahydrophthalic acid, hexahydrophthalic acid, and methylhexahydrophthalic acid. Examples of the amine compound include ethylenediamine, propylenediamine, diethylenetriamine, triethylenetetramine, metaphenylenediamine, diaminediphenylmethane, and diaminodiphenylsulfonic acid. Amine adducts of these amine compounds may be used.

  Examples of other curing agents include amide compounds, hydrazide compounds, imidazole compounds, imidazoline compounds, phenol compounds, urea compounds, and polysulfide compounds.

  Examples of the amide compound include dicyandiamide and polyamide. Examples of the hydrazide compound include dihydragit. Examples of the imidazole compound include methylimidazole, 2-ethyl-4-methylimidazole, ethyldiimidazole, isopropylimidazole, 2,4-dimethylimidazole, phenylimidazole, undecylimidazole, heptadecylimidazole, and 2-phenyl-4-methyl. Examples include imidazole. Examples of the imidazoline compound include methyl imidazoline, 2-ethyl-4-methyl imidazoline, ethyl imidazoline, isopropyl imidazoline, 2,4-dimethyl imidazoline, phenyl imidazoline, undecyl imidazoline, heptadecyl imidazoline and 2-phenyl-4-methyl imidazoline. Etc.

  An acid anhydride compound can also be used as the curing agent. By using the acid anhydride compound, discoloration of the transparent composite sheet can be further prevented. Examples of the acid anhydride compound include phthalic anhydride, maleic anhydride, trimellitic anhydride, pyromellitic anhydride, nadic anhydride, glutaric anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, hexahydrophthalate. Acid anhydride, methyl tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyl hexahydrophthalic anhydride, methyl nadic anhydride, dodecenyl succinic anhydride, dichlorosuccinic anhydride, benzophenone tetracarboxylic anhydride and Examples include chlorendic acid anhydride.

  When using together the said epoxy resin and the said acid anhydride compound, content in particular of an epoxy resin and a hardening | curing agent is not restrict | limited. The preferable lower limit of the equivalent of the acid anhydride of the acid anhydride compound is 0.5 equivalent, the more preferable lower limit is 0.7 equivalent, the preferable upper limit is 1.5 equivalent, and the more preferable upper limit with respect to 1 equivalent of the epoxy group of the epoxy resin. Is 1.2 equivalents. When there are more equivalents of the said hardening | curing agent than the said preferable minimum, coloring of a transparent composite sheet can fully be suppressed. When the equivalent of the curing agent is less than the preferable upper limit, the moisture resistance of the transparent composite sheet is improved.

  The transparent resin composition may contain a curing accelerator. The curing accelerator is not particularly limited. Examples of the curing accelerator include tertiary amines, imidazole compounds, quaternary ammonium salts, quaternary phosphonium salts, organometallic salts, phosphorus compounds, urea compounds, and the like. The curing accelerator is preferably at least one selected from the group consisting of tertiary amines, imidazole compounds and quaternary phosphonium salts. As for the said hardening accelerator, only 1 type may be used and 2 or more types may be used together.

  The content of the curing accelerator is not particularly limited. The preferable lower limit of the content of the curing accelerator is 0.05 parts by weight, the more preferable lower limit is 0.2 parts by weight, and the preferable upper limit is 7.0 parts by weight with respect to 100 parts by weight of the transparent resin (a). The upper limit is 3.0 parts by weight. When there is more content of the said hardening accelerator than the said preferable minimum, a transparent resin composition can fully be hardened. When there is less content of the said hardening accelerator than the said preferable upper limit, coloring of a transparent composite sheet can be suppressed further.

  As the transparent resin (a), a curable resin that is a thiol group-containing compound having a silsesquioxane skeleton may be used.

The thiol group-containing compound having the silsesquioxane skeleton is a hydrolysis condensate (hereinafter also referred to as a hydrolysis condensate (a1)) of a thiol group-containing silane compound represented by the following formula (1). By using a curable resin that is a thiol group-containing compound having a silsesquioxane skeleton, the transparency and heat resistance of the transparent resin cured product (A) can be further enhanced.
R1Si (OR2) ₃ ... Formula (1)

  In the above formula (1), R1 represents a C1-C8 organic group having a thiol group and no aromatic ring, or an organic group having a thiol group and an aromatic ring, and R2 is It represents a hydrogen atom, an organic group having 1 to 8 carbon atoms that does not have an aromatic ring, or an organic group that has an aromatic ring.

  Specific examples of R1 include an aliphatic hydrocarbon group having 1 to 8 carbon atoms having a thiol group, an alicyclic hydrocarbon group having 1 to 8 carbon atoms having a thiol group, or an aromatic group having a thiol group. A hydrocarbon group etc. are mentioned. Specific examples of R2 include a hydrogen atom, an aliphatic hydrocarbon group having 1 to 8 carbon atoms, an alicyclic hydrocarbon group having 1 to 8 carbon atoms, and an aromatic hydrocarbon group. The “hydrocarbon group” in the case of having a thiol group is a group containing not only a carbon atom and a hydrogen atom but also a sulfur atom derived from the thiol group. The plurality of R2s may be the same or different.

  A hydrolysis condensate (a1) can be obtained by hydrolyzing and condensing a component (hereinafter also referred to as component (a11)) containing the thiol group-containing silane compound represented by the above formula (1). That is, a hydrolysis-condensation product (a1) can be obtained by a hydrolysis reaction and a condensation reaction.

  Examples of the thiol group-containing silane compound represented by the above formula (1) include 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyltripropoxysilane, 3-mercaptopropyltributoxysilane, 1 , 4-Dimercapto-2- (trimethoxysilyl) butane, 1,4-dimercapto-2- (triethoxysilyl) butane, 1,4-dimercapto-2- (tripropoxysilyl) butane, 1,4-dimercapto- 2- (tributoxysilyl) butane, 2-mercaptomethyl-3-mercaptopropyltrimethoxysilane, 2-mercaptomethyl-3-mercaptopropyltriethoxysilane, 2-mercaptomethyl-3-mercaptopropyltripropoxysilane, 2- Mercaptomethi -3-mercaptopropyltributoxysilane, 1,2-dimercaptoethyltrimethoxysilane, 1,2-dimercaptoethyltriethoxysilane, 1,2-dimercaptoethyltripropoxysilane, and 1,2-dimercaptoethyl A tributoxysilane etc. are mentioned. Of these, 3-mercaptopropyltrimethoxysilane is preferred because of its high reactivity of hydrolysis reaction and easy availability. As for the thiol group-containing silane compound represented by the above formula (1), only one type may be used, or two or more types may be used in combination.

  When obtaining the hydrolysis-condensation product (a1), only one type of thiol group-containing silane compound represented by the above formula (1) may be used, or two or more types may be used in combination. Furthermore, when obtaining the hydrolysis-condensation product (a1), a crosslinkable compound other than the thiol group-containing silane compound may be used. As the hydrolysis condensate (a1), not only the thiol group-containing silane compound but also the thiol group-containing silane compound and a crosslinkable compound other than the thiol group-containing silane compound are used. included. The component (a11) includes the thiol group-containing silane compound represented by the formula (1) and the crosslinkable compound used as necessary.

  The transparent resin (a) is also referred to as a compound having an epoxy group (hereinafter also referred to as an epoxy compound (a2)) and a compound having an isocyanate group (hereinafter also referred to as an isocyanate compound (a3)) in addition to the hydrolysis condensate (a1). It is preferable that at least one of the above is further included. In this case, the transparent resin (a) can be efficiently crosslinked and cured by heating.

  Although it does not specifically limit as an epoxy compound (a2), For example, a phenol novolak type epoxy resin, a cresol novolak type epoxy resin, a bisphenol A type epoxy resin, a bisphenol F type epoxy resin, a bisphenol S type epoxy resin, a hydrogenated bisphenol A type epoxy Resin, hydrogenated bisphenol F type epoxy resin, stilbene type epoxy resin, triazine skeleton containing epoxy resin, fluorene skeleton containing epoxy resin, linear aliphatic epoxy resin, alicyclic epoxy resin, glycidylamine type epoxy resin, triphenol phenol methane Type epoxy resin, alkyl-modified triphenolmethane type epoxy resin, biphenyl type epoxy resin, dicyclopentadiene skeleton-containing epoxy resin, naphthalene skeleton-containing epoxy resin, and aryl Alkylene type epoxy resins. As for an epoxy compound (a2), only 1 type may be used and 2 or more types may be used together.

  The epoxy compound (a2) includes bisphenol A type epoxy resin (trade name “Epicoat 828” manufactured by Mitsubishi Chemical Corporation), bisphenol F type epoxy resin (trade name “Epicoat 807” manufactured by Mitsubishi Chemical Corporation), and hydrogenated bisphenol. A type epoxy resin (trade name “Santoto ST-3000” manufactured by Toto Kasei Co., Ltd.) or an alicyclic epoxy resin (trade name “Celoxide 2021” manufactured by Daicel Chemical Industries, Ltd.) is preferable. By using these preferable epoxy compounds (a2), the transparency and heat resistance of the transparent resin cured product (A) can be further enhanced.

  The higher molecular weight of the epoxy compound (a2) is preferable. The use of the high molecular weight epoxy compound (a2) increases the flexibility of the transparent resin cured product (A). Examples of the high molecular weight epoxy compound (a2) include epoxy resins having an epoxy equivalent of 2000 g / equivalent or more (trade names “Epicoat 1010” and “Epicoat 4007P” manufactured by Mitsubishi Chemical Corporation), and epoxy-modified silicone resins (Shin-Etsu Chemical Co., Ltd.). Trade name “X-22-163A”, etc.), and polyethylene glycol diglycidyl ether. Of these, polyethylene glycol diglycidyl ether is preferred.

  Although an isocyanate compound (a3) is not specifically limited, For example, aromatic diisocyanate, aliphatic diisocyanate, alicyclic diisocyanate, etc. are mentioned. Specific examples of the isocyanate compound (a3) include 1,5-naphthylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 4,4′-diphenyldimethylmethane diisocyanate, 4,4′-dibenzyl isocyanate, and dialkyldiphenylmethane. Diisocyanate, tetraalkyldiphenylmethane diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, tolylene diisocyanate, butane-1,4-diisocyanate, hexamethylene diisocyanate, isopropylene diisocyanate, methylene diisocyanate, 2,2,4- Trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, cyclohexane-1,4-di Socyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, lysine diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, methylcyclohexane diisocyanate, and m-tetramethylxylylene diene Examples include isocyanate and dimerized isocyanate obtained by converting a carboxyl group of dimer acid into an isocyanate group. As for an isocyanate compound (a3), only 1 type may be used and 2 or more types may be used together.

  From the viewpoint of enhancing the transparency and heat resistance of the transparent resin cured product (A), the isocyanate compound (a3) is preferably isophorone diisocyanate.

  The higher molecular weight of the isocyanate compound (a3) is preferable. The use of the high molecular weight isocyanate compound (a3) increases the flexibility of the transparent resin cured product (A). Examples of the high molecular weight isocyanate compound (a3) include a diisocyanate-modified polyol and polymer MDI (trade name “COSMONATE M” manufactured by Takeda Chemicals, Inc.). Examples of the polyol include polycarbonate diol and polyester diol.

  In order to accelerate the curing reaction of the transparent resin (a) by heating, the epoxy compound (a2) and a catalyst may be used in combination. Examples of the catalyst used in combination with the epoxy compound (a2) include tertiary amines, imidazole compounds, organic phosphines, and tetraphenyl boron salts.

  Examples of the tertiary amine include 1,8-diaza-bicyclo [5.4.0] undecene-7, triethylenediamine, benzyldimethylamine, triethanolamine, dimethylaminoethanol, and tris (dimethylaminomethyl) phenol. It is done. Examples of the imidazole compound include 2-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, and 2-heptadecylimidazole. Examples of the organic phosphine include tributylphosphine, methyldiphenylphosphine, triphenylphosphine, diphenylphosphine, and phenylphosphine. Examples of the tetraphenylboron salt include tetraphenylphosphonium tetraphenylborate, 2-ethyl-4-methylimidazole tetraphenylborate, and N-methylmorpholine tetraphenylborate.

  It is preferable to use the isocyanate compound (a3) and a catalyst in combination. Examples of the catalyst used in combination with the isocyanate compound (a3) include organotin compounds and tertiary amines.

  Examples of the organotin compound include dibutyltin dilaurate and tin octylate. Examples of the tertiary amine include 1,8-diaza-bicyclo [5.4.0] undecene-7, triethylenediamine, benzyldimethylamine, triethanolamine, dimethylaminoethanol, and tris (dimethylaminomethyl) phenol. Can be mentioned.

  The content of the catalyst used in combination with the epoxy compound (a2) and the isocyanate compound (a3) with respect to 100 parts by weight of the transparent resin (a) is preferably in the range of 0.01 to 5 parts by weight.

  In 100% by weight of the transparent resin (a), the blending ratio of the hydrolyzed condensate (a1) and at least one of the epoxy compound (a2) and the isocyanate compound (a3) can be appropriately determined according to the application.

  [Mole number of thiol group contained in hydrolysis condensate (a1)] / [Total number of moles of epoxy group contained in epoxy compound (a2) and isocyanate group contained in isocyanate compound (a3)] (hereinafter, The molar ratio C) is preferably in the range of 0.9 to 1.1. When the molar ratio C is 0.9 or more, epoxy groups and isocyanate groups hardly remain after curing, and the weather resistance of the transparent resin cured product (A) becomes high. When the molar ratio is 1.1 or less, the thiol group hardly remains, and a bad odor due to decomposition of the thiol group hardly occurs.

  The transparent resin (a) preferably further contains a compound having a carbon-carbon double bond (hereinafter also referred to as an unsaturated compound (a4)) in addition to the hydrolysis condensate (a1). By using the unsaturated compound (a4), the transparent resin composition can be cured by heating and irradiation with actinic rays.

  The unsaturated compound (a4) is not particularly limited. As said carbon-carbon double bond of an unsaturated compound (a4), a vinyl group, a (meth) acryloyl group, an allyl group, etc. are mentioned. The carbon-carbon double bond reacts with the thiol group of the hydrolysis condensate (a1) (ene-thiol reaction). The reaction mechanism of this reaction varies depending on the presence or absence of a polymerization initiator. For this reason, a hydrolysis-condensation product (a1) and an unsaturated compound (a4) are suitably adjusted to the optimal compounding quantity.

  When the polymerization initiator is not used, one thiol group undergoes an addition reaction with respect to one carbon-carbon double bond. When the polymerization initiator is used, a chain radical reaction proceeds in addition to the addition reaction of one thiol group with respect to one carbon-carbon double bond. As a result, when the polymerization initiator is not used, the thiol group contained in the hydrolysis condensate (a1) and the carbon-carbon double bond contained in the unsaturated compound (a4) are 1: 1 (moles). Ratio). When the polymerization initiator is used, the thiol group contained in the hydrolysis condensate (a1) and the carbon-carbon double bond contained in the unsaturated compound (a4) are 1: 1 (molar ratio). Then it does not react.

  From the above viewpoint, when a polymerization initiator is not used, the mixing ratio of the hydrolysis condensate (a1) and the unsaturated compound (a4), that is, [mol of thiol group contained in the hydrolysis condensate (a1)]. Number] / [number of moles of carbon-carbon double bond contained in unsaturated compound (a4)] (hereinafter also referred to as molar ratio D1) is preferably in the range of 0.9 to 1.1. The molar ratio D1 is more preferably 1.0. When the molar ratio D1 is 0.9 or more, the carbon-carbon double bond hardly remains after curing, and the weather resistance of the transparent resin cured product (A) becomes high. When the molar ratio is 1.1 or less, the thiol group hardly remains, and a bad odor due to decomposition of the thiol group hardly occurs.

  When a polymerization initiator is used, the mixing ratio of the hydrolysis condensate (a1) and the unsaturated compound (a4), that is, [number of moles of thiol groups contained in the hydrolysis condensate (a1)] / [unsaturation]. The number of moles of carbon-carbon double bonds contained in compound (a4)] (hereinafter also referred to as molar ratio D2) is preferably in the range of 0.01 to 1.1. The water vapor | steam barrier property of a transparent resin hardened | cured material (A) can be improved further as the said molar ratio D2 is 0.01 or more. Furthermore, it becomes difficult for carbon-carbon double bonds to remain after curing, and the weather resistance of the cured transparent resin (A) increases. When the molar ratio D2 is 1.1 or less, the thiol group hardly remains, and a bad odor due to decomposition of the thiol group hardly occurs.

  Moreover, in order to suppress that the functional group which has a carbon-carbon double bond reacts preferentially over reaction with the functional group which has a carbon-carbon double bond, and a thiol group, an unsaturated compound (a4) Preferably has an allyl group.

  Compounds having one allyl group include cinnamic acid, monoallyl cyanurate, monoallyl isocyanurate, pentaerythritol monoallyl ether, trimethylolpropane monoallyl ether, glycerin monoallyl ether, bisphenol A monoallyl ether, bisphenol F. Examples include monoallyl ether, ethylene glycol monoallyl ether, diethylene glycol monoallyl ether, triethylene glycol monoallyl ether, propylene glycol monoallyl ether, dipropylene glycol monoallyl ether, and tripropylene glycol monoallyl ether.

  The compounds having two allyl groups include diallyl phthalate, diallyl isophthalate, diallyl cyanurate, diallyl isocyanurate, pentaerythritol diallyl ether, trimethylolpropane diallyl ether, glyceryl diallyl ether, bisphenol A diallyl ether, bisphenol F diallyl ether, Examples include ethylene glycol diallyl ether, diethylene glycol diallyl ether, triethylene glycol diallyl ether, propylene glycol diallyl ether, dipropylene glycol diallyl ether, and tripropylene glycol diallyl ether.

  Examples of the compound containing three or more allyl groups include triallyl isocyanurate, pentaerythritol triallyl ether, pentaerythritol tetraallyl ether, and trimethylolpropane triallyl ether. The compound having an allyl group is particularly preferably triallyl isocyanurate, diallyl phthalate or pentaerythritol triallyl ether.

  The molecular weight of the unsaturated compound (a4) is preferably high. Use of the high molecular weight unsaturated compound (a4) increases the flexibility of the transparent resin cured product (A). Examples of the high molecular weight unsaturated compound (a4) include a copolymer of methylallyl siloxane and dimethyl siloxane, a copolymer of epichlorohydrin and allyl glycidyl ether (trade name “Epichromer” manufactured by Daiso Corporation, and ZEON Corporation). As well as allyl group-terminated polyisobutylene polymers (trade name “Epion” manufactured by Kaneka Corporation) and the like.

  [Mole number of carbon-carbon double bond contained in unsaturated compound (a4)] / [Mole number of unsaturated compound (a4)] (hereinafter also referred to as molar ratio E) is preferably 2 or more. The molar ratio E indicates the average number of carbon-carbon double bonds contained per molecule. When the molar ratio E is 2 or more, the curability of the transparent resin (a) increases and the crosslink density of the transparent resin cured product (A) increases. For this reason, there exists a tendency for the heat resistance and hardness of a transparent resin hardened | cured material (A) to become high.

  When the hydrolysis condensate (a1) is used, it is not necessary to use a polymerization initiator. However, the said transparent resin composition may contain the polymerization initiator, also when a hydrolysis-condensation product (a1) is included. Examples of the polymerization initiator include a photocationic polymerization initiator and a photoradical polymerization initiator. As for the said polymerization initiator, only 1 type may be used and 2 or more types may be used together.

  Examples of the cationic photopolymerization initiator include sulfonium salts, iodonium salts, metallocene compounds, and benzoin tosylate, which are compounds that generate an acid upon irradiation with ultraviolet rays. Commercially available products of the above cationic photopolymerization initiator include trade names “Syracure UVI-6970”, “Syracure UVI-6974” and “Syracure UVI-6990” manufactured by Union Carbide, and “Irgacure” manufactured by Ciba Japan. H.264 "and a trade name" CIT-1682 "manufactured by Nippon Soda Co., Ltd.

  The photo radical polymerization initiator is not particularly limited. Examples of the photo radical polymerization initiator include benzophenone, N, N′-tetraethyl-4,4′-diaminobenzophenone, 4-methoxy-4′-dimethylaminobenzophenone, 2,2-diethoxyacetophenone, benzoin, and benzoin. Methyl ether, benzoin propyl ether, benzoin isobutyl ether, benzyldimethyl ketal, α-hydroxyisobutylphenone, thioxanthone, 2-chlorothioxanthone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4- (methylthio) phenyl]- 2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1, 2-dimethylamino-2- (4-methyl-benzyl) -1- ( 4- Ruphorin-4-yl-phenyl) -butan-1-one, 2,6-dimethylbenzoyldiphenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, t-butylanthraquinone, 1-chloroanthraquinone, 2,3 -Dichloroanthraquinone, 3-chloro-2-methylanthraquinone, 2-ethylanthraquinone, 1,4-naphthoquinone, 9,10-phenanthraquinone, 1,2-benzoanthraquinone, 1,4-dimethylanthraquinone, 2-phenyl Anthraquinone, 2- (o-chlorophenyl) -4,5-diphenylimidazole dimer, 2-mercaptobenzothiazole, 2-mercaptobenzoxazole, and 4- (p-methoxyphenyl) -2,6-di- (trichloro Methyl) -s-to Examples include riadin. Among these, 1-hydroxycyclohexyl phenyl ketone is preferable because coloring of the cured resin can be suppressed. Moreover, since it has the effect of suppressing the ene-thiol reaction and can enhance the storage stability of the transparent resin (a), 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropane-1 -One, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butanone-1,2-dimethylamino-2- (4-methyl-benzyl) -1- (4-morpholine-4 Α-Aminoalkylphenone photoradical polymerization initiators such as -yl-phenyl) -butan-1-one are preferred.

  The preferable lower limit of the content of the polymerization initiator is 1 part by weight, the preferable upper limit is 15 parts by weight, the more preferable upper limit is 10 parts by weight, and the more preferable upper limit is 5 parts by weight with respect to 100 parts by weight of the transparent resin (a). is there.

  In order to further increase the storage stability of the transparent resin (a), an ene-thiol reaction inhibitor can be used. Examples of the ene-thiol reaction inhibitor include phosphorus compounds, radical polymerization inhibitors, tertiary amines, and imidazole compounds.

  Examples of the phosphorus compound include triphenylphosphine and triphenyl phosphite. Examples of the radical polymerization inhibitor include p-methoxyphenol, hydroquinone, pyrogallol, naphthylamine, tert-butylcatechol, cuprous chloride, 2,6-di-tert-butyl-p-cresol, 2,2′-methylenebis ( 4-ethyl-6-tert-butylphenol), 2,2′-methylenebis (4-methyl-6-tert-butylphenol), N-nitrosophenylhydroxylamine aluminum salt, diphenylnitrosamine and the like. Examples of the tertiary amine include benzyldimethylamine, 2- (dimethylaminomethyl) phenol, 2,4,6-tris (diaminomethyl) phenol, and diazabicycloundecene. Examples of the imidazole compound include 2-methylimidazole, 2-ethyl-4-methylimidazole, 2-ethylhexylimidazole, 2-undecylimidazole, 1-cyanoethyl-2-methylimidazole, and the like.

  Among the phosphorus compounds, triphenyl phosphite is preferable. The triphenyl phosphite has a high inhibitory effect on the ene-thiol reaction and is liquid at room temperature, so that it is easy to handle. It is preferable that content of the said phosphorus compound exists in the range of 0.1-10 weight part with respect to 100 weight part of transparent resin (a). When the content of the phosphorus compound is 0.1 parts by weight or more, the ene-thiol reaction can be sufficiently suppressed. When the content of the phosphorus compound is 10 parts by weight or less, the residual amount of the phosphorus compound decreases after curing, and a decrease in physical properties of the cured transparent resin (A) derived from the phosphorus compound can be suppressed.

  Among the radical polymerization inhibitors, N-nitrosophenylhydroxylamine aluminum salt is preferable. The N-nitrosophenylhydroxylamine aluminum salt can suppress the ene-thiol reaction even in a small amount, and can enhance the transparency of the transparent resin cured product (A). The content of the radical polymerization inhibitor is preferably in the range of 0.0001 to 0.1 parts by weight with respect to 100 parts by weight of the transparent resin (a). When the content of the radical polymerization inhibitor is 0.001 part by weight or more, the ene-thiol reaction can be sufficiently suppressed. If the content of the radical polymerization inhibitor is 0.1 parts by weight or less, the curability tends to be high.

  Of the above tertiary amines, benzyldimethylamine is preferred. The benzyldimethylamine is easy to handle because it has a high inhibitory effect on the ene-thiol reaction and is liquid at room temperature. The content of the tertiary amine is preferably in the range of 0.001 to 5 parts by weight with respect to 100 parts by weight of the transparent resin (a). When the content of the tertiary amine is 0.001 part by weight or more, the ene-thiol reaction can be sufficiently suppressed. When the content of the tertiary amine is 5 parts by weight or less, the condensation reaction of unreacted hydroxyl groups and alkoxy groups in the hydrolysis-condensation product (a1) hardly occurs, and gelation hardly occurs.

  The compounding ratio of the hydrolysis-condensation product (a1) and the unsaturated compound (a4) can be appropriately changed depending on the application. Moreover, when using together a hydrolysis-condensation product (a1) and an unsaturated compound (a4), a solvent can be mix | blended as needed.

  The Abbe number of the transparent resin cured product (A) is preferably in the range of 35-50. When the Abbe number of the transparent resin cured product (A) is within the above range, the light transmittance of the transparent composite sheet can be further increased.

  The transparent resin cured product (A) can also be obtained, for example, by curing a material to which the glass cloth (b) is not added during the production of the transparent composite sheet. The cured transparent resin (A) is, for example, a mixture obtained by mixing a transparent resin (a) and at least one of a photopolymerization initiator and a curing agent for curing the transparent resin (a). It can also be obtained by curing.

(Glass cloth (b))
The filament diameter of the glass cloth (b) is preferably 3 to 10 μm. When the filament diameter is 3 μm or more, the tensile strength is further increased. When the filament diameter is 10 μm or less, the bending strength is further increased.

  The thickness of the single yarn is preferably 10 to 20 in terms of Tex count. When it is 10 or more, the thickness of the glass cloth (b) is increased, and the effect of reducing the strength or the thermal expansion can be sufficiently obtained. If the number is 20 or less, the opening process is easy.

The number of twists of the single yarn is preferably 2 / inch or less. When the number of twists is 2 / inch or less, the opening process with an opening degree of 2 or more is easy.
The density (weave density) of the warp and weft of the glass cloth (b) is preferably 40 to 70 / inch. When the number is 40 / inch or more, the eyes (basket hole) of the glass cloth (b) are sufficiently small, and the unevenness of the surface of the transparent composite sheet can be reduced. When the number is 70 / inch or less, the opening of the glass cloth (b) is facilitated without clogging the eyes.

Since the distortion of the transparent image of the transparent composite sheet can be further reduced, the glass cloth (b) is a glass cloth that has been subjected to fiber opening treatment so that the fiber opening degree of the following formula (X) is in the range of 2 to 4. It is preferable that
Degree of spread = fiber width of the fiber bundle in the glass cloth (b) after the spread treatment / diameter of the glass fiber single yarn Formula (X)

  Since the distortion of the transparent composite sheet can be further reduced, the glass cloth (b) contained in the transparent composite sheet according to the present invention has a filament diameter of 3 to 10 μm, a Tex count of 10 to 20, and a twist. The glass cloth (b) is formed of a glass fiber single yarn of several 2 / inch or less, and a woven fabric having a density of warps and wefts of 40 to 70 / inch is obtained by opening the above formula (X). It is preferably a glass cloth that has been subjected to fiber opening treatment so that the fineness is in the range of 2 to 4.

  Since the thickness of the glass cloth (b) varies depending on the type of yarn used, the weaving density, and the degree of opening, it is difficult to define a strict range. When the thickness of glass cloth (b) is illustrated, it is a thick part where a warp and a weft cross, and it is about 40-80 micrometers.

  As the material of the glass cloth (b), soda glass, borosilicate glass, alkali-free glass, or the like is used. Of these, alkali-free glass is preferable. By using the alkali-free glass, when the transparent composite sheet is used as a display element substrate or a solar cell substrate, the alkali component derived from the glass cloth (b) does not adversely affect the semiconductor element.

  The fiber of the glass cloth (b) is preferably E glass or T glass. The E glass is widely used as a core material for glass fiber reinforced circuit boards. Regarding the fiber diameter, fiber bundle diameter, basis weight as a glass cloth, weaving density, thickness, and the like, the E glass has various standard products. Moreover, E glass is used suitably from a viewpoint of a performance improvement, cost reduction, and the availability.

  The fiber of the glass cloth (b) is more preferably T glass. T glass fiber is superior to E glass fiber in terms of high strength and low thermal expansion.

  The preferable lower limit of the tensile modulus of the glass cloth (b) is 5 GPa, the more preferable lower limit is 10 GPa, the preferable upper limit is 500 GPa, and the more preferable upper limit is 200 GPa. If the tensile modulus is too low, the strength of the transparent composite sheet tends to be low.

  The preferable lower limit of the content of the glass cloth (b) is 50 parts by weight, the more preferable lower limit is 100 parts by weight, the preferable upper limit is 300 parts by weight, and the more preferable upper limit is 200 parts by weight with respect to 100 parts by weight of the transparent resin (a). It is. When there is too little content of glass cloth (b), there exists a tendency for the reduction effect of the thermal expansion by glass cloth (b) to become inadequate. If the glass cloth (b) content is too high, it becomes difficult to impregnate the glass cloth (b) with the transparent resin (a), and voids are generated on the surface or inside of the transparent composite sheet, resulting in a decrease in transparency. It becomes easy to do.

(Other ingredients)
The transparent resin composition, the transparent resin cured product (A), and the transparent composite sheet are each a plasticizer, a weathering agent, an antioxidant, a heat stabilizer, a lubricant, and an antistatic material, depending on the needs in various applications. Agents, brighteners, colorants, conductive agents, mold release agents, surface treatment agents, viscosity modifiers, and the like may be included.

(Transparent composite sheet)
In FIG. 1, the transparent composite sheet which concerns on one Embodiment of this invention is typically shown with partial notch sectional drawing.

  As shown in FIG. 1, the transparent composite sheet 1 has a first surface 1a and a second surface 1b. In this embodiment, the 1st surface 1a has an unevenness | corrugation, and the 2nd surface 1b is a flat surface. The amplitude of the surface irregularities is 0.5 to 5 μm on the first surface 1a and 0.4 μm or less on the second surface 1b.

  The transparent composite sheet which concerns on this invention contains the transparent resin hardened | cured material (A) which the transparent resin (a) hardened | cured, and the glass cloth (b) embedded in this transparent resin hardened | cured material (A).

  As a method for producing a transparent composite sheet according to the present invention, when a glass cloth is impregnated with a transparent resin and cured, one surface is brought into contact with a rigid body such as metal or glass, and the other surface (the other surface). And a transparent resin (a) is cured in a state of being sandwiched so as to be in contact with a flexible body such as a resin film. Accordingly, surface unevenness due to curing shrinkage hardly occurs on the surface in contact with the rigid body, and surface unevenness is concentrated on the surface in contact with the flexible body. Therefore, in the obtained transparent composite sheet, one surface is flat and only the other surface has irregularities.

The rigid body has a flat surface. The rigid body preferably has at least one material selected from the group consisting of metal, glass and ceramics. The flexible body has a flat surface. The flexible body is a flexible body that is more flexible than the rigid body.
Although it does not specifically limit as a specific manufacturing method, For example, the following methods are mentioned.

  Applying a certain amount of transparent resin (a) having fluidity at room temperature or under heating onto glass cloth (b), impregnating (absorbing) transparent resin (a) into glass cloth (b), obtain. The composite material is a transparent composite material. The composite material is a glass cloth impregnated with a curable transparent resin. Next, the composite material is dried as necessary. Thereafter, the composite material is sandwiched between a metal roll and a resin film. Thereby, one surface of the composite material is brought into contact with the metal roll, and the other surface is brought into contact with the resin film. In this state, while adjusting the thickness of the transparent composite material, the thickness is made uniform, and in this state, at least one of heating and irradiation with actinic rays is performed. Thereby, the transparent composite material is crosslinked and cured to form a transparent composite sheet. Then, a transparent composite sheet is obtained by peeling from a transparent composite sheet from a metal roll and a resin film.

  When impregnating the glass cloth (b) with the transparent resin (a), the glass cloth (b) is immersed in the transparent resin (a), and the transparent resin (a) is applied while irradiating ultrasonic waves as necessary. Glass cloth (b) may be impregnated.

  Further, instead of the metal roll, a metal belt may be used, and the transparent composite material may be sandwiched between the metal belt and the resin film. Further, instead of the resin film, a flexible body that is more flexible than the rigid body may be used.

  Further, in order to surely complete the curing reaction, the transparent resin (a) may be cured only with actinic rays and then further heated.

  Alternatively, actinic rays may be applied to the composite material in contact with the rigid body while the rigid body such as a metal roll is heated. That is, heating and irradiation with actinic rays may be performed simultaneously, and curing by heating and curing by irradiation with actinic rays may proceed simultaneously.

  Further, without using a resin film, the transparent composite material may be cured in a state where one surface of the transparent composite material is brought into contact with the metal roll and nothing is brought into contact with the other surface. However, in this case, the amount of resin on the glass cloth on the surface where nothing is in contact tends to fluctuate. Therefore, the obtained transparent composite sheet is likely to warp.

  The thickness of the transparent composite sheet according to the present invention is not particularly limited. However, in consideration of the specification of the glass cloth (b) and the ratio of the transparent resin (a) and the glass cloth (b), the thickness is within a range of 25 to 200 μm. Preferably there is.

  When it is necessary to make the thickness of the transparent composite sheet thicker than 200 μm, it is cured after laminating a plurality of sheet-like transparent composite materials, or the transparent composite material is repeatedly formed and cured to form a transparent composite sheet. It is preferable to obtain Further, a plurality of transparent composite sheets may be laminated via an appropriate adhesive layer.

(Size of surface irregularities)
The transparent composite sheet according to the present invention has first and second surfaces that face each other, and the amplitude of the surface unevenness that coincides with the warp or weft cycle of the glass cloth on the surface of the sheet is 0 in the first surface. 0.5 to 5 μm and 0.4 μm or less on the second surface. As is apparent from the method for producing the transparent composite sheet described above, the surface where the transparent composite material is brought into contact with a flexible body such as a resin film has irregularities on the surface and is brought into contact with a rigid body such as metal, glass or ceramics. The surface is less likely to be uneven. Accordingly, the surface in contact with the flexible body is the first surface, and the surface in contact with the rigid body is the second surface, and the specific amplitude range is realized. From the viewpoint of further reducing the variation in the cell gap and further reducing the distortion of the transmission image, the amplitude of the surface irregularities is preferably 0.3 μm or less on the second surface. More preferably, it is 2 μm or less.

  The amplitude of the surface irregularities can be measured using a general stylus type surface shape measuring device.

  The light transmittance of the transparent composite sheet according to the present invention is preferably 80% or more, more preferably 85% or more, further preferably 90% or more, and particularly preferably 92% or more. preferable. As the light transmittance is higher, for example, when an image display device is obtained using a transparent composite sheet for a display element substrate such as a liquid crystal display element or an organic EL display element, the display quality becomes higher and the image becomes clearer. Become.

  The said light transmittance can be calculated | required by measuring the total light transmittance of wavelength 550nm using a commercially available spectrophotometer.

In order to increase the water vapor barrier property of the transparent composite sheet, the water vapor permeability of the transparent composite sheet according to the present invention is preferably 1 × 10 ⁻¹ g / m ² · day or less at 40 ° C. and 90% relative humidity. . In order to increase the dimensional stability of the transparent composite sheet, the average linear expansion coefficient at 30 to 250 ° C. of the transparent composite sheet according to the present invention is preferably 20 ppm / ° C. or less.

  The haze value of the transparent composite sheet according to the present invention is preferably 10% or less, more preferably 3% or less, and even more preferably 2% or less.

  The haze value is measured based on JIS K7136. A commercially available haze maker is used as the measuring device. Examples of the measuring device include “Fully Automatic Haze Meter TC-HIIIDPK” manufactured by Tokyo Denshoku Co., Ltd.

  A surface smoothing layer, a hard coat layer, or a gas barrier layer may be laminated on the transparent composite sheet according to the present invention.

  When forming the surface smoothing layer or hard coat layer, for example, a known surface smoothing agent or hard coat agent is applied onto the transparent composite sheet, and dried to remove the solvent as necessary. . Next, the surface smoothing agent or the hard coat agent is cured by at least one of heating and irradiation with actinic rays.

  The method for applying the surface smoothing agent or the hard coat agent on the transparent composite sheet is not particularly limited. For example, a conventionally known method such as a roll coating method, a spin coating method, a wire bar coating method, a dip coating method, an extrusion method, a curtain coating method, or a spray coating method can be employed.

The barrier property of water vapor or oxygen may be enhanced by laminating a gas barrier layer on the transparent composite sheet according to the present invention. The gas barrier layer is not particularly limited. Examples of the material for the gas barrier layer include metals such as aluminum, silicon compounds such as SiO ₂ and SiN, magnesium oxide, aluminum oxide, and zinc oxide. From the viewpoint of improving water vapor barrier properties, transparency, and adhesion to the transparent composite sheet, silicon compounds such as SiO ₂ and SiN are preferred.

  The method for forming the gas barrier layer is not particularly limited, and examples thereof include dry methods such as a vapor deposition method and a sputtering method, and wet methods such as a sol-gel method. Of these, the sputtering method is preferable. The gas barrier layer formed by the sputtering method is dense and excellent in gas barrier properties, and also has good adhesion to the transparent composite sheet.

(Application of laminated sheet and transparent composite sheet)
FIG. 2 schematically shows an example of a laminated sheet using the transparent composite sheet shown in FIG.

  As shown in FIG. 2, the laminated sheet 11 includes a transparent composite sheet 1, a polarizing plate 12, and an adhesive layer 13. The polarizing plate 12 is laminated on the first surface 1 a of the transparent composite sheet 1. The pressure-sensitive adhesive layer 13 is provided between the polarizing plate 12 and the first surface 1 a of the transparent composite sheet 1. The pressure-sensitive adhesive layer 13 is provided so as to be bonded to the polarizing plate 12 and the first surface 1 a of the transparent composite sheet 1.

  In the transparent composite sheet according to the present invention, the first surface side has larger irregularities on the surface than the second surface side. However, as described above, when the transparent composite sheet is used as a substrate of a display element such as a liquid crystal display element, for example, by laminating an adhesive layer on the first surface, the unevenness of the surface of the first surface can be reduced. What is necessary is just to reduce or eliminate an influence.

  Therefore, this invention can be used suitably for the lamination sheet used for optical uses, such as a liquid crystal display element. As such a laminated sheet, the transparent composite sheet of the present invention, a polarizing plate laminated on the first surface of the transparent composite sheet, and polarization so that the polarizing plate is bonded to the first surface of the transparent composite sheet. A laminated sheet provided with the adhesive layer provided between the board and the 1st surface of the transparent composite sheet can be mentioned. In this laminated sheet, a polarizing plate is indirectly laminated on the first surface of the transparent composite sheet. In this case, since the influence of the unevenness of the first surface of the transparent composite sheet is alleviated or eliminated by the pressure-sensitive adhesive layer, the use of the transparent pressure-sensitive adhesive layer causes distortion of the transmitted image of the light transmitted through the laminated sheet. Can be difficult.

  The laminated sheet according to the present invention has a structure in which the two transparent composite sheets of the present invention are provided and the second surfaces of the two transparent composite sheets are laminated and integrated. May be. That is, like the laminated sheet 21 shown in FIG. 3, the two transparent composite sheets 1 may be used by bonding the second surfaces 1b together. In this case, a polarizing plate is bonded to each of the first surfaces located on the outer sides of the two transparent composite sheets in the same manner as described above via an adhesive layer. In the laminated sheet thus obtained, the influence of the unevenness on the surface of the first surface is alleviated or eliminated by the pressure-sensitive adhesive layer, and in the portion where the transparent composite sheets are bonded together, Since the few second surfaces face each other, the distortion of the transmission image hardly occurs. In addition, what is necessary is just to use a suitable adhesive when bonding the 2nd surfaces of a transparent composite sheet.

  Also, a laminated sheet in which one transparent composite sheet is laminated on one surface of a member from the first surface side and another transparent composite sheet is laminated on the other surface of the member from the first surface side. As the above, the transparent composite sheet can also be used. In this laminated sheet, the outer surface is the second surface of the transparent composite sheet.

  In the present invention, the transparent composite sheet and the laminated sheet are suitably used as a light transmissive substrate of a display element such as a liquid crystal display element. As such a liquid crystal display element, a first substrate, a second substrate opposed to the first substrate with a gap, a liquid crystal layer disposed between the first and second substrates, An appropriate liquid crystal display element comprising According to the present invention, in this liquid crystal display element, at least one of the first and second substrates is the transparent composite sheet of the present invention, a polarizing plate laminated on the first surface of the transparent composite sheet, It is a laminated sheet comprising an adhesive layer provided between the first surface of the transparent composite sheet and the polarizing plate so that the polarizing plate is bonded to the first surface of the transparent composite sheet. Therefore, in the laminated sheet, the transmission image is hardly distorted, so that the display quality of the characteristics of the liquid crystal display element can be improved.

  FIG. 4 is a cross-sectional view schematically showing an example of a liquid crystal display element using the transparent composite sheet shown in FIG.

  The liquid crystal display element 31 shown in FIG. 4 includes a laminated sheet 11 that is a first substrate, a laminated sheet 11 that is a second substrate, and a liquid crystal layer 32. The laminated sheet 11 as the first substrate and the laminated sheet 11 as the second substrate are opposed to each other with a gap. A liquid crystal layer 32 is disposed between the laminated sheet 11 that is the first substrate and the laminated sheet 11 that is the second substrate. Further, the liquid crystal layer 32 includes a second surface 1b of the transparent composite sheet 1 in the laminated sheet 11 as the first substrate, and a second surface 1b of the transparent composite sheet 1 in the laminated sheet 11 as the second substrate. Is in contact with

  In this case, a laminated sheet having a structure in which two transparent composite sheets are laminated may be used. That is, a laminated sheet in which the second surfaces of two transparent composite sheets are bonded together and a polarizing plate is laminated on the outside of the first surface of each transparent composite sheet via an adhesive layer may be used. In other words, the laminated sheet has a second transparent composite sheet laminated so that the second surfaces are bonded to the second surface of the transparent composite sheet, and the first of the second transparent composite sheet. A second polarizing plate laminated on the surface, and a second pressure-sensitive adhesive layer provided between the first surface of the second transparent composite sheet and the second polarizing plate may further be provided. .

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples. The present invention is not limited only to the following examples.

Example 1
Transparent resin (a), tricyclodecane dimethanol dimethacrylate (NK ester DCP, Shin-Nakamura Chemical Co., Ltd.) 50 parts by weight and bis [4- (acryloyloxyethoxy) phenyl] fluorene (Ogsol EA-0200, Osaka) 48 parts by weight of Gas Chemical Co., Ltd.) and 0.5 parts by weight of 1-hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184, manufactured by Ciba Japan Co., Ltd.), which is a photopolymerization initiator, are added and mixed to obtain a transparent resin liquid 1 Got.

A glass cloth (b), which is E glass having a thickness of 42 μm and a weight per unit area of 48 g / m ² , was continuously immersed in the obtained transparent resin liquid 1 to impregnate the glass cloth (b) with the transparent resin liquid 1. . In this way, a transparent composite material was obtained.

Subsequently, a metal having a flat surface is formed by overlapping a 100 μm thick polyester film (product number: Cosmo Shine A4100, manufactured by Toyobo Co., Ltd.) on one side of the transparent composite material in which the glass cloth (b) is impregnated with the transparent resin liquid 1. A polyester film was laminated on the transparent composite material on a roll to make the thickness of the transparent composite material uniform. Next, the transparent composite material laminated with the polyester film is irradiated with 2000 mJ / cm ² (365 nm) of UV light from the polyester film side with a high-pressure mercury lamp while being conveyed on the metal roll, and the transparent resin in the transparent composite material Was crosslinked and cured. Thereafter, the polyester film was peeled off to obtain a transparent composite sheet.

(Example 2)
30 parts by weight of 3,4-epoxycyclohexenylmethyl-3 ′, 4′-epoxycyclohexenecarboxylate (Celoxide 2021P, manufactured by Daicel Chemical Industries), which is a transparent resin (a), and a bisarylfluorene-based epoxy resin (ONCOAT EX) -1010 (manufactured by Nagase Sangyo Co., Ltd.) 20 parts by weight of a 7: 3 (weight ratio) mixture of methylhexahydrophthalic anhydride and hexahydrophthalic anhydride as a curing agent (Licacid MH-700, manufactured by Shin Nippon Rika Co., Ltd.) 42 parts by weight and 1 part by weight of a curing accelerator (Hishicolin PX-4ET, manufactured by Nippon Chemical Industry Co., Ltd.) were added and mixed to obtain a transparent resin liquid 2.

A glass cloth (b) which is E glass having a thickness of 68 μm and a basis weight of 81 g / m ² is immersed in the obtained transparent resin liquid 2, and the transparent resin liquid 2 is applied to the glass cloth (b) while irradiating ultrasonic waves. Impregnated. In this way, a transparent composite material in which the transparent resin liquid 2 was impregnated in the glass cloth (b) was obtained.

  Thereafter, the transparent composite material was pulled up, placed on a stainless steel plate having a flat surface, and defoamed while being decompressed to a pressure of 10 Pa in a decompression chamber. The surface of the transparent composite material on the stainless steel plate taken out from the vacuum chamber is passed through a laminator while a 75 μm thick polyimide film with a flat surface (product number Kapton 300H, manufactured by Toray DuPont Co., Ltd.) is passed through to make the thickness of the transparent composite material uniform. Turned into. Next, after heating at 100 ° C. for 60 minutes in an oven, the resin was further heated at 200 ° C. for 180 minutes to crosslink and cure the transparent resin in the transparent composite material. Thereafter, the polyimide film was peeled off to obtain a transparent composite sheet.

(Example 3)
A thiol group-containing compound having a silsesquioxane skeleton which is a transparent resin (a) (HBSQ101, corresponding to the hydrolysis condensate (a1), manufactured by Arakawa Chemical Co., Ltd.) and 50 parts by weight of triallyl isocyanurate Then, 0.2 part by weight of 2-methyl-1 [4- (methylthio) phenyl] -2-morpholinopropan-1-one (Irgacure 907, manufactured by Ciba Japan), which is a photopolymerization initiator, By mixing, a transparent resin liquid 3 was obtained.

Glass cloth (b), which is E glass having a thickness of 42 μm and a weight per unit area of 48 g / m ² , was continuously immersed in the obtained transparent resin liquid 3 to impregnate the glass cloth (b) with the transparent resin liquid 3. . In this way, a transparent composite material in which the transparent resin liquid 3 was impregnated in the glass cloth (b) was obtained.

Subsequently, while laminating a 100 μm thick flat polyester film (manufactured by Toyobo Co., Ltd., product number Cosmo Shine A4100) on one side of the transparent composite material, the polyester film was laminated on the transparent composite material on a metal roll with a flat surface, The thickness was made uniform. Next, while the transparent composite material laminated with the polyester film is conveyed on a metal roll, UV light of 2000 mJ / cm ² (365 nm) is irradiated from the polyester film side to crosslink and cure the sheet-like transparent composite material. did. Thereafter, the polyester film was peeled off to obtain a transparent composite sheet.

Example 4
A transparent composite sheet was obtained in the same manner as in Example 3 except that the glass cloth (b) was changed to a glass cloth having a thickness of 92 μm and a basis weight of 104 g / m ² .

(Example 5)
To 70 parts by weight of a polysilsesquioxane solution (Composeran SQ102-1, manufactured by Arakawa Chemical Industries, Ltd., corresponding to the hydrolysis condensate (a1)) and 50 parts by weight of isophorone diisocyanate as a transparent resin (a) A dibutyltin dilaurate 0.2 part by weight was added and mixed to obtain a transparent resin liquid 4.

A glass cloth (b) which is E glass having a thickness of 68 μm and a basis weight of 81 g / m ² is immersed in the obtained transparent resin liquid 4, and the glass cloth (b) is impregnated with the transparent resin liquid 4 while irradiating ultrasonic waves. I let you. In this way, a transparent composite material was obtained.

  Thereafter, the transparent composite material was pulled up, placed on a stainless steel plate having a flat surface, and dried in an oven at 80 ° C. for 10 minutes. Next, while laminating a laminator while layering a 100 μm flat polyester film (product number: Cosmo Shine A4100, manufactured by Toyobo Co., Ltd.) on the surface of the transparent composite material on the stainless steel plate, the thickness of the transparent composite material is made uniform in the oven. The transparent composite material laminated with the polyester film was crosslinked and cured by heating at 120 ° C. for 20 minutes. Thereafter, the polyester film was peeled off to obtain a transparent composite sheet.

(Comparative Example 1)
A glass cloth (b), which is E glass having a thickness of 42 μm and a weight per unit area of 48 g / m ² , was continuously immersed in the transparent resin liquid 1 produced in Example 1, and the transparent resin liquid 1 was then added to the glass cloth (b). Impregnated. In this way, a transparent composite material was obtained.

Subsequently, the polyester film was laminated on both sides of the transparent composite material and laminated on a metal roll to make the thickness of the transparent composite material uniform. Next, UV light of 2000 mJ / cm ² (365 nm) was irradiated from the polyester film side with a high-pressure mercury lamp while being conveyed on a metal roll to crosslink and cure the transparent composite material on which the polyester film was laminated. Thereafter, the polyester film was peeled off to obtain a transparent composite sheet.

(Comparative Example 2)
A glass cloth (b), which is E glass having a thickness of 68 μm and a basis weight of 81 g / m ² , is immersed in the transparent resin liquid 2 produced in Example 2, and the transparent resin liquid 3 is glass cloth ( b) was impregnated. In this way, a transparent composite material was obtained.

  Thereafter, the transparent composite material is pulled up and placed on a 75 μm-thick polyimide film (product number Kapton 300H, manufactured by Toray DuPont Co., Ltd.) whose peripheral portion is attached and fixed to a stainless steel plate, and the pressure is reduced to 10 Pa in a vacuum chamber. While defoaming. A transparent composite material is passed through a laminator while a 75 μm thick polyimide film (product number: Kapton 300H, manufactured by Toray DuPont Co., Ltd.) is layered on the exposed surface of the transparent composite material on the stainless steel plate to which the polyimide film taken out from the vacuum chamber is attached. The material thickness was made uniform. Next, after heating for 60 minutes at 100 ° C. in an oven, it was further heated for 180 minutes at 200 ° C. to crosslink and cure the transparent composite material laminated with the polyester film. Thereafter, the polyimide film was peeled off to obtain a transparent composite sheet.

(Example 6)
The transparent resin (a) 9,9-bis [4- (2-acryloyloxyethoxy) phenyl] fluorene (A-BPEF, Shin-Nakamura Chemical Co., Ltd.) 27 parts by weight and ethoxylated isocyanuric acid triacrylate (A- 9300, manufactured by Shin-Nakamura Chemical Co., Ltd.) and 2-methyl-1 [4- (methylthio) phenyl] -2-morpholinopropan-1-one (Irgacure 907, Ciba Japan) as a polymerization initiator. 0.2 parts by weight) were added and mixed to obtain a transparent resin liquid 6.

Glass cloth (b), which is E glass having a thickness of 42 μm and a basis weight of 48 g / m ² , was continuously immersed in the transparent resin liquid 6 thus obtained, so that the glass cloth (b) was impregnated with the transparent resin liquid 6. . In this way, a transparent composite material was obtained.

Subsequently, the surface temperature is 130 ° C. while a 100 μm thick polyester film (product number: Cosmo Shine A4100, manufactured by Toyobo Co., Ltd.) is laminated on one side of the transparent composite material in which the glass cloth (b) is impregnated with the transparent resin liquid 6. A polyester film was laminated on the transparent composite material on a metal roll having a flat surface heated to uniform the thickness of the transparent composite material. Next, the transparent composite material laminated with the polyester film is irradiated with 2000 mJ / cm ² (365 nm) of UV light from the polyester film side with a high-pressure mercury lamp while being conveyed on the heated metal roll. The transparent resin inside was cross-linked and cured. After peeling from the metal roll, the polyester film was further peeled to obtain a transparent composite sheet.

(Example 7)
48 parts by weight of ethoxylated isocyanuric acid triacrylate (A-9300, manufactured by Shin-Nakamura Chemical Co., Ltd.) which is a transparent resin (a), ε-caprolactone-modified ethoxylated isocyanuric acid triacrylate (A-9300-1CL, Shin-Nakamura Chemical Industry) 1) which is a polymerization initiator in 48 parts by weight) and 4,9 parts by weight 9,9-bis [4- (2-acryloyloxyethoxy) phenyl] fluorene (A-BPEF, Shin-Nakamura Chemical Co., Ltd.) A transparent resin liquid 7 was obtained by adding 0.4 parts by weight of hydroxy-cyclohexyl-phenyl-ketone (Irgacure 184, manufactured by Ciba Japan) and mixing them.

A glass cloth (b), which is T glass having a thickness of 70 μm and a basis weight of 80 g / m ² , was continuously immersed in the transparent resin liquid 7 thus obtained to impregnate the glass cloth (b) with the transparent resin liquid 7. . In this way, a transparent composite material was obtained.

Subsequently, the surface temperature is 100 ° C. while a 100 μm thick polyester film (product number: Cosmo Shine A4100, manufactured by Toyobo Co., Ltd.) is laminated on one side of the transparent composite material in which the glass cloth (b) is impregnated with the transparent resin liquid 7. A polyester film was laminated on the transparent composite material on a metal roll having a flat surface heated to uniform the thickness of the transparent composite material. Next, the transparent composite material laminated with the polyester film is irradiated with 2000 mJ / cm ² (365 nm) of UV light from the polyester film side with a high-pressure mercury lamp while being conveyed on the heated metal roll. The transparent resin inside was cross-linked and cured. After peeling from the metal roll, the polyester film was further peeled to obtain a transparent composite sheet.

(Evaluation)
(1) Thickness of transparent composite sheet The thickness of the transparent composite sheet was measured using a thickness gauge manufactured by Ozaki Seisakusho.

(2) Refractive index The refractive index nD (wavelength 589.3 nm) was measured with a digital Abbe refractometer (manufactured by Elma). The transparent resin solutions 1 to 7 used in the examples and comparative examples were cured, and the refractive index of the cured product of the transparent resin (a) (transparent resin cured product (A)) used in the examples and comparative examples was evaluated. . The manufacturer's nominal value was adopted for the refractive index of the glass cloth (b).

(3) Surface irregularities (amplitude)
The shape of the transparent composite sheet surface was measured with a stylus type surface shape measuring device P-16 + (manufactured by KLA-Tencor). On the surface of the transparent composite sheet, on the line passing through the intersection of the warp and the weft and the point where the fiber surrounded by the warp and the weft does not exist (basket hole) in a direction that makes approximately 45 ° with the warp and the weft of the glass cloth in the sheet The surface shape was measured, and the amplitude of surface irregularities that appeared periodically at the intersection of the warp and the weft and the point (basket hole) where there was no fiber surrounded by the warp and the weft was obtained.

(4) Image clarity Based on JIS K7374, the image clarity of the obtained transparent composite sheet was measured using image clarity measuring device ICM-1T (made by Suga Test Instruments Co., Ltd.). The image definition (%) at an optical comb width of 0.125 mm was determined.

(5) Light transmittance The light transmittance at 550 nm of the obtained transparent composite sheet was measured using a spectrophotometer UV-310PC (manufactured by Shimadzu Corporation).

(6) Haze value Based on JIS K7136, the haze of the obtained transparent composite sheet was measured using fully automatic haze meter TC-HIIIDPK (made by Tokyo Denshoku Co., Ltd.).

(7) Tensile strength Based on JIS K7164, the tensile strength of the obtained transparent composite sheet was measured using the Tensilon universal material testing machine RTC-1310A (made by Orientec Corporation). The width of the test piece was 25 mm.

(8) Linear expansion coefficient After heating the obtained transparent composite sheet from 30 ° C. to 250 ° C. at a rate of 10 ° C./min, using a TMA / EXSTAR 6000 type thermal stress strain measuring device (manufactured by Seiko Denshi), Cooled to 0 ° C. at a rate of 10 ° C./min. Thereafter, the temperature was increased again at a rate of 10 ° C./min, and the average linear expansion coefficient at 30 ° C. to 250 ° C. during this temperature increase was determined.

(9) Glass transition temperature (Tg)
Using a DVA-200 viscoelasticity measuring apparatus (made by IT Measurement & Control Co., Ltd.), the obtained transparent composite sheet was heated from room temperature to 300 ° C. at a rate of 20 ° C./min, then cooled to 30 ° C., Again, the temperature was raised at a rate of 20 ° C./min and the viscoelastic properties were measured. The peak temperature of tan δ at the time of the second temperature increase was defined as the glass transition temperature.

  The results are shown in Table 1 below.

  Table 1 below shows the contents of the transparent resin (a) and the glass cloth (b) used when obtaining the transparent composite sheet.

DESCRIPTION OF SYMBOLS 1 ... Transparent composite sheet 1a ... 1st surface 1b ... 2nd surface 11 ... Laminated sheet 12 ... Polarizing plate 13 ... Adhesive layer 21 ... Laminated sheet 31 ... Liquid crystal display element 32 ... Liquid crystal layer

Claims (2)

Preparing a glass cloth impregnated with a curable transparent resin having transparency after curing;
The hardening between a rigid body having at least one material selected from the group consisting of metal, glass and ceramics and having a flat surface and a flexible body having a flat surface and more flexible than the rigid body. Sandwiching a glass cloth impregnated with a transparent transparent resin, and curing the curable transparent resin by at least one of heating and light irradiation. Wherein as a flexible member, a resin film, a transparent composite sheet manufacturing method according to claim 1.

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