JP2012036350A - Curable composition and transparent composite sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a curable composition whose cured product after curing is hard to yellow even if exposed to high temperatures and a transparent composite sheet using the curable composition.SOLUTION: The curable composition cures by irradiation with active rays. The curable composition includes a polyfunctional (meth)acrylate monomer having two or more (meth)acryloyl groups and a bismaleimide compound. The transparent composite sheet has a cured product obtained by curing the curable composition and glass fibers embedded in the cured product.

Description

  The present invention relates to a curable composition that is cured by irradiation with actinic rays. Furthermore, the present invention is used, for example, in applications requiring transparency such as a display element substrate, and a cured product obtained by curing the curable composition, and a glass fiber embedded in the cured product. The present invention relates to a transparent composite sheet.

  Glass substrates are widely used for display element substrates such as liquid crystal display elements or organic EL display elements, and solar cell substrates. However, 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.

  For example, the following Patent Document 1 discloses a plastic substrate obtained by impregnating a glass cloth with a resin composition and drying to obtain a prepreg, and then thermally curing the prepreg while pressing. Yes.

JP 2004-151291 A

  The conventional plastic substrate as described in Patent Document 1 has a problem that when it is exposed to a high temperature, it turns yellow and transparency is lowered.

  In display elements and solar cells, an inorganic material layer is often formed as a semiconductor layer or a conductive layer using an inorganic material. In the process of forming the inorganic material layer, the substrate is heated to about 220 to 300 ° C. Since the glass substrate has high heat resistance, it can withstand high temperatures of about 220 to 300 ° C. On the other hand, when a plastic substrate is used, heat resistance in the process of forming the inorganic material layer is a problem. That is, there is a problem that the heat resistance of the conventional plastic substrate as described in Patent Document 1 is lower than that of the glass substrate. The heat resistance referred to here means that the plastic material is decomposed by heating, unlike yellowing, and the plastic material is greatly deformed by heating, or the elastic modulus of the plastic material is greatly decreased by heating. It also means.

  Particularly in the use of a plastic substrate, deformation due to heating and a decrease in elastic modulus become a major problem in the process of forming an inorganic material layer. Deformation and a decrease in elastic modulus due to heating of the plastic substrate are noticeable at the boundary of the glass transition temperature of the resin material (curable compound) used for the plastic substrate. For this reason, the glass transition temperature of the resin material constituting the plastic substrate is important for the heat resistance of the plastic substrate.

  On the other hand, a technique for forming an inorganic material layer at a relatively low temperature of about 180 ° C. has been studied for the problem of heat resistance of a plastic substrate. However, in the low temperature process, it is difficult to obtain an inorganic material layer that sufficiently satisfies the characteristics as a semiconductor or a conductor and the reliability of element operation.

  An object of the present invention is to provide a curable composition that does not easily yellow even when the cured product after curing is exposed to a high temperature, and a transparent composite sheet using the curable composition.

  A limited object of the present invention is to improve the heat resistance of a cured product after curing and to provide a cured product that can withstand the process of forming an inorganic material layer at 220 ° C. or higher, and the curability It is to provide a transparent composite sheet using the composition.

  According to a wide aspect of the present invention, a curable composition that cures upon irradiation with actinic rays, comprising a polyfunctional (meth) acrylate monomer having two or more (meth) acryloyl groups, and a bismaleimide compound, A curable composition is provided.

  The curable composition is preferably a curable composition in which glass fibers are embedded in a cured product after curing. The curable composition according to the present invention is desirably used for obtaining a transparent composite sheet having a cured product obtained by curing the curable composition and glass fibers embedded in the cured product.

  In a specific aspect of the curable composition according to the present invention, the polyfunctional (meth) acrylate monomer has a triazine skeleton or a pentaerythritol skeleton.

  In another specific aspect of the curable composition according to the present invention, the polyfunctional (meth) acrylate monomer includes a polyfunctional (meth) acrylate monomer having a triazine skeleton represented by the following formula (1).

  In the above formula (1), R1 to R6 each represent a hydrogen atom or a methyl group, and n1 to n3 each represent 1 or 2.

  In another specific aspect of the curable composition according to the present invention, the polyfunctional (meth) acrylate monomer includes a polyfunctional (meth) acrylate having a pentaerythritol skeleton.

  In still another specific aspect of the curable composition according to the present invention, the bismaleimide compound is a bismaleimide compound represented by the following formula (3).

  In said formula (3), R21-R24 respectively represents a hydrogen atom or a methyl group, and R25 and R26 represent a hydrogen atom, a methyl group, or an ethyl group, respectively.

  In another specific aspect of the curable composition according to the present invention, the glass transition temperature of the cured product after curing is 220 ° C. or higher.

  The transparent composite sheet which concerns on this invention has the hardened | cured material which hardened the curable composition comprised according to this invention, and the glass fiber embedded in this hardened | cured material.

  On the specific situation with the transparent composite sheet which concerns on this invention, the said glass fiber is E glass.

  In another specific aspect of the transparent composite sheet according to the present invention, the light transmittance at a wavelength of 550 nm is 85% or more.

  In another specific aspect of the transparent composite sheet according to the present invention, the average linear expansion coefficient at 50 to 200 ° C is 20 ppm / ° C or less.

  In still another specific aspect of the transparent composite sheet according to the present invention, the thickness is 25 to 200 μm.

  The curable composition of the present invention is a curable composition that is cured by irradiation with actinic rays, and includes a polyfunctional (meth) acrylate monomer having two or more (meth) acryloyl groups, and a bismaleimide compound. Does not easily turn yellow when exposed to high temperatures.

  Hereinafter, the present invention will be described in detail.

  The curable composition concerning this invention is a curable compound hardened | cured by irradiation of actinic light. The curable composition concerning this invention contains the polyfunctional (meth) acrylate monomer which has 2 or more of (meth) acryloyl groups, and a bismaleimide compound.

  The present inventors have found that a curable composition containing a bismaleimide compound tends to yellow when a cured product obtained by curing the curable composition is heated to a high temperature. Therefore, as a result of studying to suppress yellowing, by using a polyfunctional (meth) acrylate monomer together with a bismaleimide compound, yellowing even when a cured product obtained by curing a curable composition is exposed to a high temperature. I found it difficult. Furthermore, transparency of the cured product of the curable composition can be improved by employing the above composition. For example, the haze value of the cured product can be 10% or less, and can be 5% or less. Therefore, a transparent transparent composite sheet can be obtained by using the curable composition according to the present invention. Moreover, since hardened | cured material does not easily yellow at high temperature, the high transparency of hardened | cured material and a transparent composite sheet can be maintained over a long period of time.

  Furthermore, the heat resistance of the hardened | cured material of a curable composition can be made high by employ | adopting the said structure. The heat resistance referred to here means that the plastic material is decomposed by heating, unlike yellowing, and the plastic material is greatly deformed by heating, or the elastic modulus of the plastic material is greatly decreased by heating. It also means.

  In display elements and solar cells, an inorganic material layer is often formed as a semiconductor layer or a conductive layer using an inorganic material. In the process of forming the inorganic material layer, the substrate is heated to about 220 to 300 ° C. Since the heat resistance of the cured product of the curable composition according to the present invention is high, it can withstand the process of forming an inorganic material layer at 220 ° C. or higher. Even when the cured product of the curable composition according to the present invention is exposed to a high temperature of 220 ° C. or higher, it is difficult to decompose, hardly deform, and the elastic modulus is hardly lowered.

  The curable composition according to the present invention is preferably a curable composition in which glass fibers are embedded. The curable composition according to the present invention is preferably used for obtaining a transparent composite sheet having a cured product obtained by curing the curable composition and glass fibers embedded in the cured product. The curable composition according to the present invention is preferably a curable composition in which E glass, which is a glass fiber, is embedded.

  The transparent composite sheet which concerns on this invention has the hardened | cured material which hardened the curable composition, and the glass fiber embedded in this hardened | cured material. The said transparent composite sheet can be obtained by hardening a curable composition by irradiation of actinic light. The transparent composite sheet can be obtained, for example, by impregnating glass fiber with a curable composition and then curing the curable composition.

  Hereinafter, first, the detail of each component contained in the curable composition concerning this invention and the transparent composite sheet concerning this invention is demonstrated.

[Curable compound]
The curable composition concerning this invention contains the polyfunctional (meth) acrylate monomer which has 2 or more of (meth) acryloyl groups. The polyfunctional (meth) acrylate monomer is a polyfunctional (meth) acrylate compound. The polyfunctional (meth) acrylate monomer is a curable compound and a polymerizable compound. “(Meth) acryloyl” refers to acryloyl and methacryloyl. “(Meth) acryl” refers to acrylic and methacrylic. “(Meth) acrylate” refers to acrylate and methacrylate.

  In order to sufficiently suppress yellowing of the cured product of the curable composition, the (meth) acrylate monomer used in the present invention needs to have two or more (meth) acryloyl groups. With a monofunctional (meth) acrylate monomer, it is difficult to sufficiently suppress yellowing of the cured product. In order to further suppress the yellowing of the cured product, the polyfunctional (meth) acrylate monomer preferably has three or more (meth) acryloyl groups.

  As the polyfunctional (meth) acrylate monomer, a (meth) acrylate monomer having a triazine skeleton, a (meth) acrylate having a pentaerythritol skeleton such as pentaerythritol tri (meth) acrylate and pentaerythritol di (meth) acrylate, and a fluorene skeleton And polyfunctional (meth) acrylate monomer, triethylene glycol di (meth) acrylate, and trimethylolpropane tri (meth) acrylate. Polyfunctional (meth) acrylate monomers other than these may be used. As for a polyfunctional (meth) acrylate monomer, only 1 type may be used and 2 or more types may be used together.

  From the viewpoint of further suppressing yellowing of the cured product at a high temperature and further increasing the heat resistance of the cured product, the polyfunctional (meth) acrylate monomer preferably has a triazine skeleton or a pentaerythritol skeleton. The polyfunctional (meth) acrylate monomer preferably has a triazine skeleton, and preferably has a pentaerythritol skeleton. From the viewpoint of further suppressing yellowing of the cured product at a high temperature and further improving the heat resistance of the cured product, the polyfunctional (meth) acrylate monomer has a pentaerythritol skeleton and a hydroxyl group-containing polyfunctional group. It is preferable to contain a functional (meth) acrylate.

  From the viewpoint of further suppressing yellowing of the cured product at a high temperature and further enhancing the heat resistance of the cured product, the polyfunctional (meth) acrylate monomer has a triazine skeleton represented by the following formula (1). It is preferably at least one of a polyfunctional (meth) acrylate monomer having a polyfunctional (meth) acrylate monomer having a pentaerythritol skeleton represented by the following formula (2). The polyfunctional (meth) acrylate monomer preferably includes a polyfunctional (meth) acrylate monomer having a triazine skeleton represented by the following formula (1), and has a pentaerythritol skeleton represented by the following formula (2). It is preferable that a polyfunctional (meth) acrylate monomer is included. The polyfunctional (meth) acrylate monomer is preferably a polyfunctional (meth) acrylate monomer having a triazine skeleton represented by the following formula (1), and has a pentaerythritol skeleton represented by the following formula (2). A polyfunctional (meth) acrylate monomer is preferred.

  In the above formula (1), R1 to R6 each represent a hydrogen atom or a methyl group, and n1 to n3 each represent 1 or 2.

  In the above formula (2), R11 represents a hydroxy group or a group represented by the following formula (2a), and R12 and R13 each represents a hydrogen atom or a methyl group.

  In the above formula (2a), R14 represents a hydrogen atom or a methyl group.

  A polyfunctional (meth) acrylate monomer having a triazine skeleton represented by the above formula (1) (hereinafter sometimes abbreviated as polyfunctional (meth) acrylate monomer (1)) and the above formula (2). The refractive index of a polyfunctional (meth) acrylate monomer having a pentaerythritol skeleton (hereinafter sometimes abbreviated as polyfunctional (meth) acrylate monomer (2)) is 1.530 or more and 1.545 or less. By mixing this polyfunctional (meth) acrylate monomer (1) and an appropriate refractive index adjusting agent, the difference between the refractive index of the cured product and the refractive index of the glass fiber is reduced, thereby improving the transparency of the transparent composite sheet. It can be made even higher.

  Moreover, the glass transition temperature of the hardened | cured material of a polyfunctional (meth) acrylate monomer (1) is about 250-280 degreeC. Therefore, by using the polyfunctional (meth) acrylate monomer (1), the heat resistance of the cured product of the curable composition can be increased, and the glass transition temperature of the cured product can be easily set to 220 ° C. or higher. . Moreover, the curable composition which gives the hardened | cured material which can endure the high temperature process which forms the inorganic material layer in a display element and a solar cell can be obtained by use of a polyfunctional (meth) acrylate monomer (1).

  The refractive index of the cured product of the polyfunctional (meth) acrylate monomer (1) is relatively low. Therefore, the refractive index of the hardened | cured material of a curable composition can be 1.557 or more and 1.571 or less by selecting suitably the component which raises a refractive index, and using it with a (meth) acrylate compound. The refractive index adjuster is preferably a refractive index improver.

  The bismaleimide compound also functions as a refractive index adjusting agent. However, other refractive index adjusting agents may be used.

  The bismaleimide compound is not particularly limited. Examples of the bismaleimide compound include N, N ′-(1,3-phenylene) bismaleimide, N, N ′-[1,3- (2-methylphenylene)] bismaleimide, N, N ′-[ 1,3- (4-methylphenylene)] bismaleimide, N, N ′-(1,4-phenylene) bismaleimide, bis (4-maleimidophenyl) methane, bis (3-methyl-4-maleimidophenyl) methane 3,3′-dimethyl-5,5′-diethyl-4,4′-diphenylmethane bismaleimide, bis (4-maleimidophenyl) ether, bis (4-maleimidophenyl) sulfone, bis (4-maleimidophenyl) sulfide Bis (4-maleimidophenyl) ketone, bis (4-maleimidocyclohexyl) methane, 1,4-bis (4-maleimidophenyl) Nyl) cyclohexane, 1,4-bis (maleimidomethyl) cyclohexane, 1,4-bis (maleimidomethyl) benzene, 1,3-bis (4-maleimidophenoxy) benzene, 1,3-bis (3-maleimidophenoxy) Benzene, bis [4- (3-maleimidophenoxy) phenyl] methane, bis [4- (4-maleimidophenoxy) phenyl] methane, 1,1-bis [4- (3-maleimidophenoxy) phenyl] ethane, 1, 1-bis [4- (4-maleimidophenoxy) phenyl] ethane, 1,2-bis [4- (3-maleimidophenoxy) phenyl] ethane, 1,2-bis [4- (4-maleimidophenoxy) phenyl] Ethane, 2,2-bis [4- (3-maleimidophenoxy) phenyl] propane, 2,2-bis [4- 4-maleimidophenoxy) phenyl] propane, 2,2-bis [4- (3-maleimidophenoxy) phenyl] butane, 2,2-bis [4- (4-maleimidophenoxy) phenyl] butane, 2,2-bis [4- (3-maleimidophenoxy) phenyl] -1,1,1,3,3,3-hexafluoropropane, 2,2-bis [4- (4-maleimidophenoxy) phenyl] -1,1,1 , 3,3,3-hexafluoropropane, 4,4-bis (3-maleimidophenoxy) biphenyl, 4,4-bis (4-maleimidophenoxy) biphenyl, bis [4- (3-maleimidophenoxy) phenyl] ketone Bis [4- (4-maleimidophenoxy) phenyl] ketone, 2,2′-bis (4-maleimidophenyl) disulfide, bis (4- Maleimidophenyl) disulfide, bis [4- (3-maleimidophenoxy) phenyl] sulfide, bis [4- (4-maleimidophenoxy) phenyl] sulfide, bis [4- (3-maleimidophenoxy) phenyl] sulfoxide, bis [4 -(4-maleimidophenoxy) phenyl] sulfoxide, bis [4- (3-maleimidophenoxy) phenyl] sulfone, bis [4- (4-maleimidophenoxy) phenyl] sulfone, bis [4- (3-maleimidophenoxy) phenyl ] Ether, bis [4- (4-maleimidophenoxy) phenyl] ether, 1,4-bis [4- (4-maleimidophenoxy) -α, α-dimethylbenzyl] benzene, 1,3-bis [4- ( 4-maleimidophenoxy) -α, α-dimethylbenzyl] 1,4-bis [4- (3-maleimidophenoxy) -α, α-dimethylbenzyl] benzene, 1,3-bis [4- (3-maleimidophenoxy) -α, α-dimethylbenzyl] benzene, 1,4-bis [4- (4-maleimidophenoxy) -3,5-dimethyl-α, α-dimethylbenzyl] benzene, 1,3-bis [4- (4-maleimidophenoxy) -3,5-dimethyl -Α, α-dimethylbenzyl] benzene, 1,4-bis [4- (3-maleimidophenoxy) -3,5-dimethyl-α, α-dimethylbenzyl] benzene, 1,3-bis [4- (3 -Maleimidophenoxy) -3,5-dimethyl-α, α-dimethylbenzyl] benzene, 4-methyl-1,3-phenylenebismaleimide, polyphenylmethanemaleimide and the like. . As for the said bismaleimide compound, only 1 type may be used and 2 or more types may be used together.

  From the viewpoint of further suppressing the yellowing of the cured product, the bismaleimide compound is preferably a bismaleimide compound represented by the following formula (3). By using a bismaleimide compound represented by the following formula (3) (hereinafter sometimes abbreviated as bismaleimide compound (3)), yellowing of the cured product at a high temperature can be remarkably suppressed. The bismaleimide compound (3) also functions as a refractive index adjusting agent.

  In said formula (3), R21-R24 respectively represents a hydrogen atom or a methyl group, and R25 and R26 represent a hydrogen atom, a methyl group, or an ethyl group, respectively.

  The bismaleimide compound (3) is uniformly compatible with the polyfunctional (meth) acrylate monomer (1). Also by this, the hardened | cured material of a curable composition comes to have high transparency with respect to visible light.

  The glass transition temperature of the cured product of the bismaleimide compound is relatively high. The glass transition temperature of the cured product of the bismaleimide compound (3) is 250 to 300 ° C. Therefore, by using the bismaleimide compound in combination with the polyfunctional (meth) acrylate monomer (1) or the polyfunctional (meth) acrylate monomer (2), the glass transition temperature of the cured product of the curable composition is further increased, The heat resistance of the cured product can be further increased. In particular, by using the bismaleimide compound (3) in combination with the polyfunctional (meth) acrylate monomer (1) or the polyfunctional (meth) acrylate monomer (2), the glass transition temperature of the cured product of the curable composition is further increased. In addition, the heat resistance of the cured product can be further increased.

  The transparent composite sheet according to the present invention is obtained by embedding glass fibers in a curable composition and curing the curable composition. In the transparent composite sheet according to the present invention, higher transparency is exhibited by bringing the refractive indexes of the cured product of the curable composition and the glass fiber closer to each other.

  In general, in order to obtain sufficient transparency applicable to a display element substrate or the like, a refractive index difference between a cured product of a curable compound serving as a matrix and a glass fiber embedded in the cured product is 0.005 or less. Is desirable. In reality, it is difficult to completely match the refractive index of the cured product of the curable compound serving as the matrix and the refractive index of the glass fiber over the entire visible light range. In the present invention, light scattering can be minimized by appropriately designing the refractive index of the cured product of the curable compound serving as the matrix for the glass fiber.

  In the present invention, it is preferable to use E glass as the glass fiber. The refractive index of E glass at 589 nm is about 1.560. By setting the refractive index at 589 nm of the cured product of the curable composition to 1.557 or more and 1.571 or less, light scattering of the transparent composite sheet having the cured product of the curable composition and glass fibers, that is, haze value Can be minimized.

  In the curable composition concerning this invention, the refractive index in 589 nm of the hardened | cured material of a transparent curable composition is 1. by adjusting suitably the kind and usage-amount of a polyfunctional (meth) acrylate monomer and a refractive index regulator. It can be adjusted to 557 or more and 1.571 or less. The refractive index at 589 nm of the cured product of the curable composition according to the present invention is preferably 1.557 or more, more preferably 1.560 or more, preferably 1.571 or less, more preferably 1.568 or less. . When the refractive index of the cured product is not less than the above lower limit and not more than the above upper limit, the transparency of the transparent composite sheet can be increased, and the haze value of the transparent composite sheet can be further reduced.

  From the viewpoint of further suppressing the yellowing of the cured product, the content of the polyfunctional (meth) acrylate monomer is 10 to 99 wt% in the total of 100 wt% of the polyfunctional (meth) acrylate monomer and the bismaleimide compound. And the content of the bismaleimide compound is preferably 1 to 90% by weight, the content of the polyfunctional (meth) acrylate monomer is 50 to 90% by weight, and the content of the bismaleimide compound is 10 to 10%. It is preferably 50% by weight. Furthermore, from the viewpoint of further suppressing the yellowing of the cured product, the content of the polyfunctional (meth) acrylate monomer is 10 to 99% by weight and the content of the bismaleimide compound in 100% by weight of the curable compound. Is preferably 1 to 90% by weight, the polyfunctional (meth) acrylate monomer content is preferably 50 to 90% by weight, and the bismaleimide compound content is preferably 10 to 50% by weight.

  The glass transition temperature of the cured product of the curable composition according to the present invention is preferably 220 ° C. or higher so that it can withstand the process of forming the inorganic material layer at 220 ° C. or higher. In the process of forming the inorganic material layer, the substrate may be heated to 235 ° C. or higher. Therefore, the glass transition temperature of the cured product of the curable composition according to the present invention is preferably 235 ° C. or higher.

  The curable composition according to the present invention preferably contains a polymerization initiator in order to cure the curable compound by polymerization.

  The curable composition which concerns on this invention is a curable composition hardened | cured by irradiation of actinic light. The curable composition is preferably a curable composition that is cured by light irradiation. The curable composition according to the present invention may further contain a curable compound that can be cured by heating. In this case, curing by heating and curing by actinic rays may be used in combination. From the viewpoint of shortening the reaction time and completing the curing reaction, it is preferable to cure the curable composition by heating after curing the curable composition with actinic rays.

  The active light is preferably ultraviolet light. Examples of the light source for irradiating the ultraviolet light include a metal halide type and a high-pressure mercury lamp lamp. When the curable composition is cured by heating, an oven and a heater are used. In order to suppress coloring due to oxidation and deterioration of the curable compound, when the curable composition is cured by heating, it is preferably heated at 150 to 300 ° C. for 1 to 24 hours in a nitrogen atmosphere or in a vacuum state. .

  In order to cure the curable composition by heating, the curable composition preferably contains a thermal polymerization initiator. The thermal polymerization initiator is preferably a radical polymerization initiator. Examples of the radical polymerization initiator include peroxide radical polymerization initiators, azo radical polymerization initiators, and redox radical polymerization initiators. Thermal polymerization initiators other than these may be used. As for the said thermal-polymerization initiator, only 1 type may be used and 2 or more types may be used together.

  Examples of the azo radical polymerization initiator include azobisisobutyronitrile, azobiscyclohexanecarbonitrile, and azobisdimethylvaleronitrile.

  Examples of the peroxide radical polymerization initiator include a diacyl radical polymerization initiator, a peroxyester radical polymerization initiator, a dialkyl radical polymerization initiator, a carbonate radical polymerization initiator, and a ketone peroxide radical polymerization start. Agents and the like. Examples of the diacyl radical polymerization initiator include lauroyl peroxide and benzoyl peroxide. Examples of the peroxyester radical polymerization initiator include t-butyl peroxybenzoate, t-butyl peroxyacetate, t-butyl peroxypivalate, and t-butyl peroxy-2-ethylhexanoate. . Examples of the dialkyl radical polymerization initiator include dicumyl peroxide and di-t-butyl peroxide. Examples of the percarbonate-based radical polymerization initiator include diisopropyl peroxydicarbonate. Examples of the ketone peroxide radical polymerization initiator include methyl ethyl ketone peroxide.

  The redox radical polymerization initiator includes, for example, a peroxide and a reducing agent or a metal-containing compound. Specific examples of the redox radical polymerization initiator include a mixture of benzoyl peroxide and organic amines, a mixture of the peroxyester radical polymerization initiator and a reducing agent such as mercaptans, and methyl ethyl ketone peroxide and organic. Examples thereof include a mixture with a cobalt salt.

  From the viewpoint of further increasing the toughness of the cured product, a peroxide radical polymerization initiator is preferred. The amount of the thermal polymerization initiator used is not particularly limited. The content of the thermal polymerization initiator is preferably 0.05 to 5 parts by weight with respect to 100 parts by weight of the curable compound in the curable composition.

  Since the curable composition concerning this invention contains a polyfunctional (meth) acrylate monomer, it superpose | polymerizes and hardens | cures effectively by irradiation of actinic light. Therefore, in order to cure the curable composition by irradiation with actinic rays, the curable composition preferably contains a photopolymerization initiator. Examples of the photopolymerization initiator include a photo radical polymerization initiator and a photo cationic polymerization initiator. The photopolymerization initiator is preferably a radical photopolymerization initiator. As for a photoinitiator, only 1 type may be used and 2 or more types may be used together.

  The photo radical polymerization initiator is not particularly limited, and examples thereof include benzophenone, N, N′-tetraethyl-4,4′-diaminobenzophenone, 4-methoxy-4′-dimethylaminobenzophenone, and 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-1,2,6-dimethylbenzoyldiphenylphosphine Xoxide, 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-mercapto Examples include benzothiazole, 2-mercaptobenzoxazole, and 4- (p-methoxyphenyl) -2,6-di- (trichloromethyl) -s-triazine. As for the said radical photopolymerization initiator, only 1 type may be used and 2 or more types may be used together.

  It does not specifically limit as said photocationic polymerization initiator, For example, a sulfonium salt, an iodonium salt, a metallocene compound, a benzoin tosylate etc. are mentioned. As for the said photocationic polymerization initiator, only 1 type may be used and 2 or more types may be used together.

  Commercially available products of the above cationic photopolymerization initiator include Cyracure UVI-6970, Cyracure UVI-6974, and Cyracure UVI-6990 (all manufactured by Union Carbide), Irgacure 264 (Ciba Japan), and CIT-1682 ( Nippon Soda Co., Ltd.).

  The content of the photopolymerization initiator is preferably 0.01 to 10 parts by weight with respect to 100 parts by weight of the curable compound in the curable composition. A curable composition can fully be hardened as content of the said photoinitiator is more than the said minimum. When the content of the polymerization initiator is less than or equal to the above upper limit, polymerization does not proceed rapidly, and problems such as increased birefringence, coloring, and cracking during curing are less likely to occur.

  When the photopolymerization initiator is a photoradical polymerization initiator, the content of the photoradical polymerization initiator is preferably 0.01% by weight with respect to 100 parts by weight of the curable compound in the curable composition. Part or more, more preferably 0.1 part by weight or more, preferably 2 parts by weight or less, more preferably 1 part by weight or less.

  When the photopolymerization initiator is a photocationic polymerization initiator, the content of the photocationic polymerization initiator is preferably 1 part by weight or more with respect to 100 parts by weight of the curable compound in the curable composition. , Preferably 10 parts by weight or less, more preferably 5 parts by weight or less.

  The said curable composition may contain the other curable compound different from the polyfunctional (meth) acrylate monomer and bismaleimide compound mentioned above. The other curable compound may be a thermosetting compound or a photocurable compound.

  The other curable compound is not particularly limited, and examples thereof include a polyfunctional thiol compound and an epoxy compound. The curable composition preferably contains a polyfunctional thiol compound or an epoxy compound, and more preferably contains a polyfunctional thiol compound. When the curable composition further contains a polyfunctional thiol compound or an epoxy compound, the curing rate and the flexibility, toughness and chemical resistance of the cured product can be adjusted or improved. The epoxy compound is preferably a polyfunctional epoxy compound.

  Examples of the polyfunctional thiol compound include 1,2-ethanedithiol, 1,2-propanedithiol, 1,3-propanedithiol, 1,3-butanedithiol, 1,4-butanedithiol, and 2,3-butane. Dithiol, 1,5-pentanedithiol, 1,6-hexanedithiol, 1,9-nonanedithiol, 1,8-octanedithiol, 1,10-decanedithiol, 1,4-butanediol bisthiopropionate, 1 , 4-butanediol bisthioglycolate, ethylene glycol bisthioglycolate, ethylene glycol bisthiopropionate, 1,2-benzenedithiol, 1,3-benzenedithiol, 1,4-benzenedithiol, toluene-3, 4-dithiol, 3,6-dichloro-1,2-benzenedithio 1,5-naphthalenedithiol, 1,2-benzenedimethanethiol, 1,3-benzenedimethanethiol, 1,4-benzenedimethanethiol, 4,4′-thiobisbenzenethiol, 2-di- n-butylamino-4,6-dimercapto-s-triazine, 2,5-dimercapto-1,3,4-thiadiazole, 1,8-dimercapto-3,6-dioxaoctane, 1,5-dimercapto-3 -Thiapentane, 1,4-bis (3-mercaptobutyryloxy) butane, trimethylolpropane tristhioglycolate, trimethylolpropane tristhiopropionate, trimethylolpropane tris (3-mercaptobutyrate), pentaerythritol tetrakis Thioglycolate, pentaerythritol tetrakisthiopro Onate, pentaerythritol tetrakis (3-mercaptobutyrate), trimercaptopropionic acid tris (2-hydroxyethyl) isocyanurate, 1,3,5-tris (3-mercaptobutyloxyethyl) -1,3,5-triazine -2,4,6-trione, 1,4-dimethylmercaptobenzene, 2,4,6-trimercapto-s-triazine, 2- (N, N-dibutylamino) -4,6-dimercapto-s-triazine And thiol group-containing silsesquioxane compounds. As a commercial item of the thiol group containing silsesquioxane compound which is the said polyfunctional thiol compound, Arakawa Chemical Industries "composeran HBSQ series" etc. are mentioned.

  In general, the use of a polyfunctional thiol compound improves the curability of the cured composition, as well as the flexibility and toughness of the cured product. On the other hand, when there is too much usage-amount of a polyfunctional thiol compound, the glass transition temperature of hardened | cured material will fall easily. Therefore, the content of the polyfunctional thiol compound in 100% by weight of the curable compound is preferably 2% by weight or more, preferably 40% by weight or less, more preferably 20% by weight or less.

  From the viewpoint of further improving the curability of the cured composition and the flexibility and toughness of the cured product while suppressing a decrease in the glass transition temperature of the cured product, the above-mentioned polyfunctional thiol compound is a trimercaptopropionic acid tris. (2-hydroxyethyl) isocyanurate, 1,3,5-tris (3-mercaptobutyloxyethyl) -1,3,5-triazine-2,4,6-trione, or thiol group-containing silsesquioxane compound It is preferable that The thiol group-containing silsesquioxane compound is preferably “Composeran HBSQ series” manufactured by Arakawa Chemical Industries.

  A conventionally well-known epoxy resin can be used as said epoxy compound. Examples of the epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, triglycidyl isocyanurate type epoxy resin, and hindant-in type epoxy resin. , Alicyclic epoxy resin, aliphatic epoxy resin, naphthalene type epoxy resin, glycidyl ether type epoxy resin, biphenyl type epoxy resin, dicyclopentadiene type epoxy resin, ester type epoxy resin, ether ester type epoxy resin, etc. . You may use the water additive or modified material of these epoxy resins. From the viewpoint of preventing discoloration of the curable composition, a bisphenol A type epoxy resin, an alicyclic epoxy resin, a triglycidyl isocyanurate type epoxy resin or a dicyclopentadiene type epoxy resin is preferable. As for the said epoxy compound, only 1 type may be used and 2 or more types may be used together.

  The curable composition according to the present invention may contain a curing agent. The curable composition concerning this invention may contain the epoxy compound and the hardening | curing agent. Examples of the curing agent include organic acids, amine compounds, amide compounds, hydrazide compounds, imidazole compounds, imidazoline compounds, phenol compounds, urea compounds, polysulfide compounds, and acid anhydrides. As for the said hardening | curing agent, only 1 type may be used and 2 or more types may be used together.

  Examples of the organic acid 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. These amine adducts may be used as the curing agent.

  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.

  From the viewpoint of preventing discoloration of the curable composition, the curing agent is preferably an acid anhydride. Examples of the acid anhydride include phthalic anhydride, maleic anhydride, trimellitic anhydride, pyromellitic anhydride, nadic acid anhydride, glutaric anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, hexahydrophthalic acid Anhydride, methyl tetrahydrophthalic anhydride, hexahydrophthalic anhydride, methyl hexahydrophthalic anhydride, methyl nadic anhydride, dodecenyl succinic anhydride, dichlorosuccinic anhydride, benzophenone tetracarboxylic anhydride and chlorophene Examples include Rendic acid anhydride.

  The compounding ratio of the epoxy compound and the curing agent is not particularly limited. The acid anhydride equivalent is preferably 0.5 equivalents or more, more preferably 0.7 equivalents or more, preferably 1.5 equivalents or less, more preferably 1.2 equivalents with respect to 1 equivalent of the epoxy group of the epoxy compound. It is as follows. When the equivalent of the acid anhydride is not less than the above lower limit, the transparency of the cured product is further enhanced. The moisture resistance of hardened | cured material becomes it high that the said acid anhydride equivalent is below the said upper limit.

  The curable composition according to the present invention may contain a curing accelerator. The curing accelerator is not particularly limited, and examples thereof include tertiary amines, imidazoles, quaternary ammonium salts, quaternary phosphonium salts, organometallic salts, phosphorus compounds and urea compounds. Of these, tertiary amines, imidazoles or quaternary phosphonium salts are particularly preferred. 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 preferably 0.05 parts by weight or more, more preferably 0.2 parts by weight or more, preferably 7.0 parts by weight or less, more preferably 100 parts by weight of the epoxy compound. 3.0 parts by weight or less. A curable composition can fully be hardened as content of the said hardening accelerator is more than the said minimum. When the content of the curing accelerator is not more than the above upper limit, the transparency of the cured product is further increased.

  The curable composition according to the present invention may contain a solvent, if necessary, for the purpose of adjusting the viscosity. The solvent is preferably a solvent that does not react with the components in the curable composition. A volatile solvent is preferred because it needs to be removed by heating in an oven or hot plate and reduced pressure in a vacuum chamber before the curing reaction of the curable composition.

  The curable composition according to the present invention includes a weathering agent, an antioxidant, a heat stabilizer, an antistatic agent, a whitening agent, a colorant, a conductive agent, a release agent, a surface treatment agent, and a viscosity as necessary. It may contain a regulator or the like.

(Transparent composite sheet)
The transparent composite sheet which concerns on this invention has the hardened | cured material which hardened the said curable composition, and the glass fiber embedded in this hardened | cured material.

  After making the curable composition concerning this invention into a sheet form, a transparent composite sheet can be obtained by bridge | crosslinking and hardening a curable composition by irradiation of irradiation of actinic light.

  Examples of the glass fiber include chopped strands of glass fiber, woven fabric of glass fiber, and nonwoven fabric of glass fiber. The glass fiber is preferably a glass fiber woven fabric.

  As the glass fiber woven fabric, for example, a yarn obtained by twisting about 100 to 800 long fibers (filaments) having a circular or oval cross section and a longest cross sectional diameter of about 3 to 10 μm is used as a warp. And obtained by weaving these yarns so as to cross each other. Examples of the weaving method include plain weave, twill weave and satin weave.

  The thickness of the glass fiber is the thickest part and is usually 10 to 500 μm. The thickness of the glass fiber is the thickest part, and is preferably 15 to 350 μm.

  The glass fiber is preferably E glass. By the combined use of the curable composition according to the present invention and E glass, the haze value of the transparent composite sheet can be considerably reduced. 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 performance, cost, and availability. Instead of E glass, T glass may be used.

  The tensile elastic modulus of the glass fiber is preferably 5 GPa or more, more preferably 10 GPa or more, preferably 500 GPa or less, more preferably 200 GPa or less. The intensity | strength of a transparent composite sheet becomes it high that the said tensile elasticity modulus is more than the said minimum.

  The thickness of the transparent composite sheet of the present invention is not particularly limited. The thickness of the transparent composite sheet according to the present invention is preferably 20 to 1000 μm. When the thickness of the transparent composite sheet is 20 μm or more, sufficient strength and rigidity can be maintained as a display device substrate. When the thickness of the transparent composite sheet is 1000 μm or less, volume shrinkage at the time of curing the curable composition becomes small, a phase difference due to residual stress hardly occurs, and a display contrast is hardly lowered. Furthermore, when the thickness of the transparent composite sheet is 1000 μm or less, the transparent composite sheet is difficult to warp, and the thickness of the transparent composite sheet becomes uniform.

  Since it can use suitably for the use of a display element and a solar cell, the thickness of the transparent composite sheet which concerns on this invention becomes like this. More preferably, it is 25 micrometers or more, More preferably, it is 200 micrometers or less. Even when the thickness of the transparent composite sheet is not less than the above lower limit and not more than the above upper limit, the heat resistance can be sufficiently enhanced. The “thickness” indicates an average thickness.

  Regarding glass fiber cloths such as glass cloth and glass nonwoven fabric, only one sheet may be used, or a plurality of sheets may be used in a stacked manner.

  When the thickness of the transparent composite sheet exceeds 1000 μm, the transparent composite sheet according to the present invention may be cured after being divided into a plurality of sheets and laminated. Furthermore, a sheet laminate may be obtained by repeating sheeting and curing.

  The light transmittance at 550 nm of the transparent composite sheet according to the present invention is preferably 80% or more, more preferably 85% or more, and further preferably 90% or more. If the light transmittance is 90% or more, for example, when an image display device is obtained using a transparent composite sheet as a liquid crystal display device substrate or an organic EL display device substrate, a clear image with high display quality is obtained. It is done. The light transmittance can be determined by measuring the total light transmittance at a wavelength of 550 nm using a commercially available spectrophotometer.

  The haze value of the transparent composite sheet according to the present invention is preferably 10% or less, more preferably 7% or less, still more preferably 5% or less, and particularly preferably 4% 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.

  From the viewpoint of enhancing the dimensional stability of the transparent composite sheet, the average linear expansion coefficient at 50 to 200 ° C. of the transparent composite sheet according to the present invention is preferably 20 ppm / ° C. or less.

  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 hard coat agent is cured by heating or irradiation with actinic rays.

  The method for applying the surface smoothing agent or the hard coating agent on the transparent composite sheet is not particularly limited, and examples thereof include a roll coating method, a spin coating method, a wire bar coating method, a dip coating method, an extrusion method, and a curtain coating. Conventionally known methods such as a method and a spray coating method can be employed.

The gas barrier layer is not particularly limited, and for example, a metal such as aluminum, a silicon compound such as SiO ₂ and SiN, a transparent material such as magnesium oxide, aluminum oxide, and zinc oxide can be used. Among them, the gas barrier properties, because excellent adhesion and transparency to the substrate layer, it is preferable to use a silicon compound such as SiO ₂ and SiN.

  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. Among these, the sputtering method is particularly preferable from the viewpoint of forming a dense gas barrier layer having excellent gas barrier properties and good adhesion to a substrate.

  The transparent composite sheet which concerns on this invention is used suitably for the plastic substrate for liquid crystal display elements, the plastic substrate for organic EL display elements, a solar cell substrate, a touch panel, etc.

  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
70 parts by weight of tris (2-acryloyloxyethyl) isocyanurate (“A-9300” manufactured by Shin-Nakamura Chemical Co., Ltd.) was mixed with 3,3′-dimethyl-5,5′-diethyl-4,4′-diphenylmethane bismaleimide ( 30 parts by weight of “MBI-5100” manufactured by Daiwa Kasei Co., Ltd.) and 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one (Ciba Japan) as a photopolymerization initiator “Irgacure 907”, 0.2 part by weight, was added while stirring at 150 ° C., and mixed and dissolved to prepare a curable composition.

  As glass fiber, a glass cloth (manufactured by Nittobo Co., Ltd.) corresponding to IPC # 2013, which is E glass fiber, was prepared. The glass cloth was immersed in a curable composition heated to 100 ° C., and the glass cloth was impregnated with the curable composition while being irradiated with ultrasonic waves. Then, the glass cloth impregnated with the curable composition was pulled up and placed on the release-treated glass plate. The glass cloth impregnated with the curable composition on the glass plate was covered with a PET film having a thickness of 100 μm (“Cosmo Shine A4100” manufactured by Toyobo Co., Ltd.) and passed through a laminator to make the thickness uniform.

Next, from the PET film side, ultraviolet rays of 12000 mJ / cm ² (365 nm) were irradiated with a high-pressure mercury lamp to cure the curable composition. Further, the cured sheet was peeled from the PET film and the glass plate to obtain a transparent composite sheet. The thickness of the obtained transparent composite sheet was 80 μm.

(Example 2)
60 parts by weight of tris (2-acryloyloxyethyl) isocyanurate (“A-9300” manufactured by Shin-Nakamura Chemical Co., Ltd.) was mixed with 3,3′-dimethyl-5,5′-diethyl-4,4′-diphenylmethane bismaleimide ( 31 parts by weight of “MBI-5100” manufactured by Daiwa Kasei Co., Ltd., 9 parts by weight of a silsesquioxane compound having a plurality of thiol groups (“Composeran HBSQ101” manufactured by Arakawa Chemical Industries), and 2-methyl-1- [4 -(Methylthio) phenyl] -2-morpholinopropan-1-one (“Irgacure 907” manufactured by Ciba Japan Co., Ltd.) is added in an amount of 0.2 part, and the mixture is stirred while heating to 150 ° C. It melt | dissolved and the curable composition was prepared.

  Using the obtained curable composition, a transparent composite sheet was obtained under the same operations and conditions as in Example 1. The thickness of the obtained transparent composite sheet was 75 μm.

(Example 3)
Isocyanuric acid tris (2-acryloyloxyethyl) (“A-9300” manufactured by Shin-Nakamura Chemical Co., Ltd.) (55 parts by weight) was mixed with 3,3′-dimethyl-5,5′-diethyl-4,4′-diphenylmethane bismaleimide ( 20 parts by weight of “MBI-5100” manufactured by Daiwa Kasei Co., Ltd., 25 parts by weight of a silsesquioxane compound having a plurality of thiol groups (“Composeran HBSQ101” manufactured by Arakawa Chemical Industries), and 2-methyl-1- [4 -(Methylthio) phenyl] -2-morpholinopropan-1-one (“Irgacure 907” manufactured by Ciba Japan Co., Ltd.) is added in an amount of 0.2 part, and the mixture is stirred while heating to 150 ° C. It melt | dissolved and the curable composition was prepared.

  Using the obtained curable composition, a transparent composite sheet was obtained under the same operations and conditions as in Example 1. The thickness of the obtained transparent composite sheet was 75 μm.

Example 4
70 parts by weight of pentaerythritol triacrylate (“PE-3A” manufactured by Kyoeisha Chemical Co., Ltd.) is mixed with 3,3′-dimethyl-5,5′-diethyl-4,4′-diphenylmethane bismaleimide (“MBI-” manufactured by Daiwa Kasei Co., Ltd.). 5100 ") 30 parts by weight and 0.2 part by weight of 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one (" Irgacure 907 "manufactured by Ciba Japan) Was added while stirring at 120 ° C., and mixed and dissolved to prepare a curable composition.

  Using the obtained curable composition, a transparent composite sheet was obtained under the same operations and conditions as in Example 1. The thickness of the obtained transparent composite sheet was 80 μm.

(Example 5)
56 parts by weight of pentaerythritol triacrylate (“PE-3A” manufactured by Kyoeisha Chemical Co., Ltd.) and 3,3′-dimethyl-5,5′-diethyl-4,4′-diphenylmethane bismaleimide (“MBI-” manufactured by Daiwa Kasei Co., Ltd.) 5100 ") 20 parts by weight, 24 parts by weight of a silsesquioxane compound having a plurality of thiol groups (" Composeran HBSQ101 "manufactured by Arakawa Chemical Industries, Ltd.) and 2-methyl-1- [4- (methylthio) phenyl]- 2-Morifolinopropan-1-one (“Irgacure 907” manufactured by Ciba Japan Co., Ltd.) is added in an amount of 0.2 part, and the mixture is stirred and heated to 120 ° C., and mixed and dissolved. Was prepared.

  Using the obtained curable composition, a transparent composite sheet was obtained under the same operations and conditions as in Example 1. The thickness of the obtained transparent composite sheet was 75 μm.

(Comparative Example 1)
56 parts by weight of triallyl isocyanurate, 20 parts by weight of 3,3′-dimethyl-5,5′-diethyl-4,4′-diphenylmethane bismaleimide (“MBI-5100” manufactured by Daiwa Kasei) and a plurality of thiols 24 parts by weight of a silsesquioxane compound having a group (“Composeran HBSQ101” manufactured by Arakawa Chemical Industries, Ltd.) and 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one ( Ciba Japan Co., Ltd. “Irgacure 907”) 0.2 parts by weight was added, stirred while heating to 120 ° C., mixed and dissolved to prepare a curable composition.

  Using the obtained curable composition, a transparent composite sheet was obtained under the same operations and conditions as in Example 1. The thickness of the obtained transparent composite sheet was 80 μm.

(Comparative Example 2)
23 parts by weight of triallyl isocyanurate, 34 parts by weight of 3,3′-dimethyl-5,5′-diethyl-4,4′-diphenylmethane bismaleimide (“MBI-5100” manufactured by Daiwa Kasei Co., Ltd.) and a plurality of thiols 43 parts by weight of a silsesquioxane compound having a group (“Composeran HBSQ101” manufactured by Arakawa Chemical Industries, Ltd.) and 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one ( Ciba Japan Co., Ltd. “Irgacure 907”) 0.2 parts by weight was added, stirred while heating to 120 ° C., mixed and dissolved to prepare a curable composition.

  Using the obtained curable composition, a transparent composite sheet was obtained under the same operations and conditions as in Example 1. The thickness of the obtained transparent composite sheet was 80 μm.

(Comparative Example 3)
23 parts by weight of triallyl cyanurate, 34 parts by weight of 3,3′-dimethyl-5,5′-diethyl-4,4′-diphenylmethane bismaleimide (“MBI-5100” manufactured by Daiwa Kasei) 43 parts by weight of a silsesquioxane compound having a group (“Composeran HBSQ101” manufactured by Arakawa Chemical Industries, Ltd.) and 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one ( Ciba Japan Co., Ltd. “Irgacure 907”) 0.2 parts by weight was added, stirred while heating to 120 ° C., mixed and dissolved to prepare a curable composition.

  Using the obtained curable composition, a transparent composite sheet was obtained under the same operations and conditions as in Example 1. The thickness of the obtained transparent composite sheet was 75 μm.

(Evaluation)
a) Refractive index Two glass plates subjected to release treatment were prepared. The curable composition obtained by sandwiching the two glass plates at an interval of 100 μm is sandwiched between the glass plates and irradiated with 12000 mJ / cm ² (365 nm) of UV light with a high-pressure mercury lamp. The product was crosslinked and cured. Thereafter, the cured product was peeled off from the glass plate and subjected to heat treatment in an oven at 200 ° C. for 1 hour to prepare a test piece (cured product). The refractive index nD (sodium D line (589 nm), 25 ° C.) of the test piece was measured using an Abbe refractometer (“NAR-1T” manufactured by Atago Co., Ltd.). For the refractive index of the glass fiber, the manufacturer (Nittobo) nominal value was adopted.

b) Linear expansion coefficient After heating the transparent composite sheet obtained at a rate of 10 ° C./min from 30 ° C. to 300 ° C. using a thermal stress strain measuring device (“TMA / EXSTAR 6000 type” manufactured by Seiko Electronics Co., Ltd.) And cooled to 30 ° C. at a rate of 20 ° C./min. Thereafter, the average linear expansion coefficient at 50 ° C. to 200 ° C. when the temperature of the transparent composite sheet was increased from 30 ° C. to 300 ° C. at a rate of 10 ° C./1 minute was obtained again.

c) Glass transition temperature Using a dynamic viscoelasticity measuring apparatus ("DVA-200" manufactured by IT Measurement Control Co., Ltd.), the temperature of the transparent composite sheet obtained from 30 ° C to 300 ° C at a rate of 10 ° C / min Then, the measurement in the tensile mode was performed. The peak temperature of tan δ was defined as the glass transition temperature. This glass transition temperature corresponds to the glass transition temperature of a cured product obtained by curing the curable composition.

d) 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). When the light transmittance is 85% or more, the transparency is excellent.

e) Haze value The haze value of the transparent composite sheet obtained was measured using a haze meter ("Fully automatic haze meter TC-HIIIDPK" manufactured by Tokyo Denshoku Co., Ltd.). When the haze value is 5% or less, the transparency is excellent.

e) Yellowing The obtained transparent composite sheet was heated in an oven at 220 ° C. for 1 hour. Based on JIS Z8722, the yellow index value (YI) value of the transparent composite sheet before heating and the transparent composite sheet after heating was measured using a spectrophotometric colorimeter (manufactured by Tokyo Denshoku Co., Ltd.). From the measured value, the degree of yellowing (ΔYI: YI value of the transparent composite sheet after heating−YI value of the transparent composite sheet before heating) was determined.

  The evaluation results are shown in Table 1 below.

Claims (12)

A curable composition that cures upon irradiation with actinic rays,
A curable composition comprising a polyfunctional (meth) acrylate monomer having two or more (meth) acryloyl groups and a bismaleimide compound. A curable composition used by embedding glass fibers in a cured product after curing, and cured by irradiation with actinic rays,
A curable composition comprising a polyfunctional (meth) acrylate monomer having two or more (meth) acryloyl groups and a bismaleimide compound.   The curable composition according to claim 1 or 2, wherein the polyfunctional (meth) acrylate monomer has a triazine skeleton or a pentaerythritol skeleton. The curable composition according to claim 3, wherein the polyfunctional (meth) acrylate monomer includes a polyfunctional (meth) acrylate monomer having a triazine skeleton represented by the following formula (1).

In the formula (1), R1 to R6 each represent a hydrogen atom or a methyl group, and n1 to n3 each represent 1 or 2. The curable composition according to claim 3 or 4, wherein the polyfunctional (meth) acrylate monomer includes a polyfunctional (meth) acrylate having a pentaerythritol skeleton. The curable composition according to any one of claims 1 to 5, wherein the bismaleimide compound is a bismaleimide compound represented by the following formula (3).

In said formula (3), R21-R24 represents a hydrogen atom or a methyl group, respectively, R25 and R26 represent a hydrogen atom, a methyl group, or an ethyl group, respectively.   The curable composition of any one of Claims 1-6 whose glass transition temperature of the hardened | cured material after hardening is 220 degreeC or more. A cured product obtained by curing the curable composition according to any one of claims 1 to 7,
A transparent composite sheet comprising glass fibers embedded in the cured product.   The transparent composite sheet according to claim 8, wherein the glass fiber is E glass.   The transparent composite sheet of Claim 8 or 9 whose light transmittance in wavelength 550nm is 85% or more.   The transparent composite sheet of any one of Claims 8-10 whose average linear expansion coefficient in 50-200 degreeC is 20 ppm / degrees C or less.   The transparent composite sheet according to any one of claims 8 to 11, having a thickness of 25 to 200 µm.