JP2005290286A - Transparent hybrid sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a hybrid sheet that is obtained by improving performance of a plastic substrate, has excellent performances such as strength, rigidity, toughness, transparency, heat resistance, light resistance, gas barrier properties, coefficient of thermal expansion, double refractive index, etc., and is suitable as a transparent substrate. <P>SOLUTION: In a hybrid sheet obtained by impregnating a glass cloth with an organic-inorganic hybrid resin comprising a metal alkoxide and a thermosetting resin as constituent elements and curing the resin, the transparent hybrid sheet has a relation represented by formula n<SB>2</SB>-0.05&le;n<SB>1</SB>&le;n<SB>2</SB>+0.05 between the refractive index (n<SB>1</SB>) of the hybrid resin and the refractive index (n<SB>2</SB>) of glass constituting the glass cloth and has &ge;50 &mu;m thickness. <P>COPYRIGHT: (C)2006,JPO&amp;NCIPI

Description

  The present invention relates to a transparent sheet suitable for a transparent substrate such as a touch panel or a dye-sensitized solar cell (a solar cell using a photocatalyst).

  Transparent substrates are used for touch panels and dye-sensitized solar cells. In this method, a transparent conductive film is formed on a substrate to impart conductivity, and an input signal is propagated and a generated current is taken out. A transparent substrate is essential. For these applications, glass substrates were conventionally used as transparent substrates. However, as the development of small-sized portable devices has progressed, the need for plastic substrates that are lightweight and have excellent impact resistance and workability has increased. Yes.

  As a transparent sheet for a plastic substrate, a product obtained by molding a thermoplastic resin by extrusion molding, injection molding, compression molding, casting or the like has been proposed. For example, Patent Document 1 discloses a method for producing a dye-sensitized solar cell using a film such as polymethyl methacrylate, polystyrene, polyethylene terephthalate, polyethylene naphthalate, polyethersulfone, or polycarbonate.

  Further, a thermosetting transparent resin formed by casting, casting or the like has been proposed. For example, Patent Document 2 discloses a transparent touch panel made of a specific photocurable resin, and Patent Document 3 discloses a transparent resin sheet made of a photocurable resin, a manufacturing method thereof, and the like.

  However, these plastic substrates still have many practical problems in terms of transparency, heat resistance, light resistance, rigidity, gas barrier properties, thermal expansion coefficient, birefringence, and the like as compared with glass substrates. Generally, since thermosetting resin has low strength and toughness, it is used as a fiber-reinforced composite material using glass fiber or the like as a reinforcing material. However, the composite material has low light transmittance and is not suitable for optical use.

  On the other hand, research and development of organic-inorganic hybrid resins having both characteristics of organic polymers and inorganic materials have been actively conducted in recent years. This organic-inorganic hybrid resin is characterized in that inorganic fine particles are dispersed in an organic polymer, and a chemical bond or interaction is formed between the polymer and the inorganic fine particles.

  In the case of a hybrid resin composed of a transparent polymer and inorganic fine particles having a sufficiently small particle size, the light transmittance is good, and the heat resistance, gas barrier property, coefficient of thermal expansion, etc. are given the characteristic effects of inorganic materials. It is expected as a material that combines high heat resistance and transparency.

  For example, Patent Document 4 discloses a film made of a polymethyl methacrylate copolymer-zirconia hybrid. Patent Document 5 discloses a silane-modified epoxy resin composition and a cured product thereof. However, these organic-inorganic hybrid resins have the disadvantage that they have lower toughness and inferior impact resistance than conventional plastics, so that it is difficult to use them alone as a plastic substrate.

JP 2003-59546 A JP-A-10-105335 JP 2003-285338 A JP 2003-147148 A JP 2002-179762 A

  In response to these demands, plastic substrates using various transparent plastics have been proposed. However, although all of these are superior to the glass substrate in terms of weight reduction and impact strength, the heat resistance, rigidity, birefringence, etc., which are the characteristics of the glass substrate, are reduced, and there are many problems in practical use. This is the reason why a new transparent substrate that combines the characteristics of a glass substrate and a plastic substrate is strongly desired.

  The present invention is a hybrid sheet suitable for a transparent substrate, which improves the performance of a plastic substrate and has excellent performance in strength, rigidity, toughness, transparency, heat resistance, rigidity, gas barrier properties, thermal expansion coefficient, birefringence, etc. The purpose is to provide.

  As a result of diligent research to achieve the above-mentioned problems, the present inventors have impregnated a specific organic-inorganic hybrid resin into a glass cloth and cured it to achieve transparency, heat resistance, and impact resistance. It is excellent and can be used as a transparent sheet suitable for transparent substrates such as touch panels and dye-sensitized solar cells, and its rigidity, gas barrier properties, thermal expansion coefficient, birefringence, etc. are greatly improved compared to conventional plastic sheets. The headline and the present invention were completed.

That is, according to the invention, the glass cloth is impregnated with a specific organic-inorganic hybrid resin having a refractive index difference within ± 0.05 with respect to the glass cloth, and the interface between the resin and the glass is sufficiently wetted. Transparent sheet that is transparent and has excellent performance in strength, rigidity, toughness, heat resistance, light resistance, rigidity, gas barrier property, thermal expansion coefficient, birefringence, etc. Can be provided.
The present invention is a transparent hybrid sheet having a configuration as described below.

(1) In a hybrid sheet obtained by impregnating a glass cloth with an organic-inorganic hybrid resin having a metal alkoxide and a thermosetting resin as components, and curing the organic-inorganic hybrid resin, the refractive index (n ₁ ) And the refractive index (n ₂ ) of the glass constituting the glass cloth,
n ₂ −0.05 ≦ n ₁ ≦ n ₂ +0.05
A transparent hybrid sheet having a thickness of 50 μm or more.
(2) The transparent hybrid sheet according to (1), wherein the metal alkoxide is at least one selected from silane alkoxide, zirconium alkoxide, titanium alkoxide, and aluminum alkoxide.
(3) The metal alkoxide is a silane alkoxide and is a silane compound represented by the following general formula (1) and / or a partial condensate thereof, or a reactive silane represented by the following general formula (2): The transparent hybrid sheet according to (1) above, which is a mixture with a compound.
^{_{(R 1) x -Si- (OR}} 2) 4-x (1)
^{_{(R 3) y -Si- (OR}} 2) 4-y (2)
In the formula, R ¹ is CH ₃ or C ₆ H ₅ , R ² is CH ₃ or C ₂ H ₅ , x is 0 to 2, and R ³ is a functional group that reacts with the thermosetting resin to form a bond. Organic chain, y is 1 or 2

(4) The organic-inorganic hybrid resin contains at least one kind of resin containing a fluorene group and / or at least one kind of metal alkoxide represented by the following general formula (3). (3) Transparent hybrid sheet.
_{(C 6 H 5) z -Si-} (OR 2) 4-z (3)
In the formula, R ² is CH ₃ or C ₂ H ₅ , z is 1 or 2
(5) The transparent hybrid sheet according to (4) above, wherein the resin containing a fluorene group is a fluorene group-containing epoxy resin.
(6) The transparent hybrid sheet according to the above (1) to (5), wherein the glass cloth is E glass.

  The transparent hybrid sheet obtained by the present invention is used for transparent substrates used in touch panels and dye-sensitized solar cells, and has strength, rigidity, toughness, transparency, heat resistance, rigidity, gas barrier properties, thermal expansion coefficient, birefringence index. The present invention provides a novel transparent sheet having excellent performance.

  The present invention has been achieved by utilizing the excellent characteristics of the organic-inorganic hybrid resin and the glass cloth reinforced composite material and by imparting excellent light transmittance by matching the refractive indexes of both. The total light transmittance of the transparent hybrid sheet of the present invention is preferably 70% or more, and more preferably 80% or more.

  Despite the fact that each of the reinforcing material and the matrix resin has transparency alone, the light transmittance is reduced when it is made into a composite material because of the difference in refractive index between the reinforcing fiber and the matrix resin and the lack of both at the interface. This is caused by complete wetting and minute voids remaining in the fiber bundle. The inventors have sufficiently impregnated the glass cloth with a hybrid resin having a difference in refractive index within the range of ± 0.05 with respect to the refractive index of the glass cloth, and without leaving residual bubbles in the fiber. By curing, a hybrid sheet having excellent light transmittance and visibility could be obtained.

  Also, since the elastic modulus is usually lowered above the Tg of plastic, the processing temperature of the plastic substrate is limited to below Tg. However, in the transparent sheet of the present invention using an organic-inorganic hybrid resin, the glass transition temperature of the hybrid resin is low. It has been found that the substrate can be processed at high temperature because it greatly increases and the elastic modulus decrease in the temperature range exceeding the glass transition temperature is small.

  As the glass cloth used in the present invention, glass fiber having no absorption in the visible light region is used. The type of glass is not particularly limited, but generally, a glass cloth made of E glass is easily available and economically preferable. In order to improve the wettability, affinity and adhesion between the glass fiber and the matrix resin, it is preferable to use a glass cloth surface-treated with a suitable silane coupling agent or various surfactants.

  The thickness, weaving density, and weaving structure of the glass cloth are selected according to the target hybrid sheet. Moreover, in order to improve resin impregnation property and surface unevenness, a glass cloth in which a yarn bundle is physically opened is suitable.

In the present invention, the difference in refractive index between the glass cloth and the matrix resin needs to be within ± 0.05. That is, the refractive index (n ₁ ) of the organic-inorganic hybrid resin and the refractive index (n ₂ ) of the glass constituting the glass cloth have a relationship of n ₂ −0.05 ≦ n ₁ ≦ n ₂ +0.05. is required.

  Various methods for producing an organic-inorganic hybrid resin are known. The organic-inorganic hybrid resin of the present invention includes a metal alkoxide and a thermosetting resin as constituent elements. Here, the component means that it is used as a raw material.

  More preferable examples of the metal alkoxide used in the present invention include silane alkoxide (= alkoxysilane), zirconium alkoxide, titanium alkoxide and the like. A hybrid resin containing zirconium alkoxide or titanium alkoxide has a high refractive index and is suitable as the hybrid resin of the present invention. However, the hydrolysis reaction is fast and handling is necessary. On the other hand, since alkoxysilane has a relatively slow hydrolysis reaction and is excellent in handleability, alkoxysilane is frequently used as an organic-inorganic hybrid resin raw material.

  As the alkoxysilane, a non-reactive silane compound represented by the following general formula (1) and / or a partial condensate thereof, or a mixture of them and a reactive silane compound represented by the following general formula (2) is used. The As the partial condensate, T resin (condensate of mono-substituted trialkoxysilane), QT resin (condensate of mono-substituted trialkoxysilane and methyl silicate), DT resin (di-substituted dialkoxysilane and mono-substituted trialkoxysilane) Condensate) is used.

_{^{(R 1) x -Si- (OR}} 2) 4-x (1)
In the formula, R ¹ is CH ₃ or C ₆ H ₅ , R ² is CH ₃ or C ₂ H ₅ , x is 0 to 2
^{_{(R 3) y -Si- (OR}} 2) 4-y (2)
In the formula, R ³ is an organic chain having a functional group that reacts with a thermosetting resin to form a bond by heating, and y is 1 or 2

  The alkoxysilane represented by the general formula (2) is a silane coupling agent having a functional group that reacts with and forms a bond with a thermosetting resin. For example, when the thermosetting resin is an epoxy, a glycidyl group is used. In the case of a silane coupling agent having an amino group, a mercapto group or the like, or an acrylate resin, a silane coupling agent having a methacryl group, a styryl group, a mercapto group, a vinyl group or the like is selected. These are effective for strengthening the bond between the polymer and the inorganic fine particles in the hybrid resin.

  As the thermosetting resin used in the present invention, any can be used as long as the cured product is transparent. For example, a transparent epoxy resin, allyl resin, unsaturated polyester resin, vinyl ester resin, polyimide resin, or the like is suitable.

  JP-A-10-45871, JP-A-2004-35821 and the like include a fluorene-containing epoxy resin, a fluorene-containing acrylate resin, a fluorene-containing epoxy acrylate resin, and other thermosetting resins and compositions containing a fluorene group, Although a cured product thereof is disclosed, a resin containing a fluorene group in the molecule is originally suitable for the resin used in the present invention because of its high refractive index and high heat resistance.

  Thermosetting resins can be used alone or in combination. For example, a mixture of a fluorene-containing epoxy resin and bisphenol A, bisphenol F, naphthalene epoxy resin, or the like can be given. Moreover, it is not necessary for all the resin components to be thermosetting resins, and thermoplastic resins and additives can be mixed and used as long as transparency and other necessary characteristics are not impaired.

In the present invention, in order to increase the refractive index of the organic-inorganic hybrid resin, at least one resin containing a fluorene group is contained, or at least one aromatic silane represented by the following general formula (3) in alkoxysilane. It is preferable to include.
_{(C 6 H 5) z -Si-} (OR 2) 4-z (3)
Where z is 1 or 2

  The resin containing a fluorene group does not necessarily need to be thermosetting, and it is also useful to use a polycarbonate or polyarylate having a fluorene group in combination with another thermosetting resin. As the fluorene group-containing resin, a fluorene-containing epoxy resin is particularly preferable.

  Although the organic-inorganic hybrid resin of the present invention is cured by heat or light, the curing agent is selected from a photocuring agent, a thermosetting agent, or the like that does not color the cured product. For example, an epoxy resin hybrid can be selected from commonly used curing agents and curing accelerators such as amine compounds, acid anhydride compounds, amide compounds, phenol compounds, and organic phosphine compounds.

  A cured product of a fluorene group-containing epoxy resin is transparent as an acid anhydride or polysilane, and is one of suitable curing agents. In the present invention, known photoacid generators can be used, and onium salts and metallocene complexes are preferred.

As the onium salt, a diazonium salt, a sulfonium salt, an iodonium salt, a phosphonium salt, a selenium salt, and the like are used. As counter ions thereof, CF ₃ SO ₃ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , AsF ₆ ⁻ and SbF are used. ₆ ^- anion, such as is used.

Specific examples include triphenylsulfonium triflate, 4-chlorobenzenediazonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium hexafluorophosphate, (4-phenylthiophenyl) diphenylsulfonium hexafluoroantimonate, (4 -Phenylthiophenyl) diphenylsulfonium hexafluorophosphate, bis [4- (diphenylsulfonio) phenyl] sulfide-bis-hexafluoroantimonate, bis [4- (diphenylsulfonio) phenyl] sulfide-bis-hexafluorophosphate, (4-Methoxyphenyl) diphenylsulfonium hexafluoroantimonate, (4-methoxyphenyl) phenyl Over de hexafluoroantimonate, bis (4-t- butylphenyl) iodonium hexafluorophosphate, benzyltriphenylphosphonium hexafluoroantimonate, triphenyl selenium hexafluorophosphate, (eta ⁵ - isopropylbenzene) (eta ⁵ - cyclo Pentadienyl) iron (II) hexafluorophosphate and the like. These compounds may be used alone or in combination of two or more.

  The method for producing a transparent hybrid sheet from an organic-inorganic hybrid resin and a glass cloth is to dilute the hybrid resin with a solvent, impregnate the glass cloth with a resin varnish whose viscosity has been adjusted, volatilize the solvent, and then apply heat or ultraviolet irradiation. A method of curing is taken.

  The resin varnish is prepared by uniformly mixing a curing agent with a solvent and adjusting the viscosity. As the solvent, tetrahydrofuran, methyl cellosolve, methyl ethyl ketone or the like is used. Before preparing the varnish, it is preferable to prepare a hybrid precursor by reacting the thermosetting resin with the alkoxysilane and the partial condensate thereof in advance.

  Thermosetting resins can be used alone or in combination. For example, a mixture of a fluorene-containing epoxy resin and bisphenol A, bisphenol F, naphthalene epoxy resin, or the like can be given.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples of the present invention, but the present invention is not limited to these examples. The hybrid sheet is evaluated by the following method.

[Measurement of Refractive Index] Using an automatic ellipsometer type ESM-1 manufactured by Nippon Vacuum Technology Co., Ltd., a He—Ne laser (wavelength: 633 nm) was measured at a temperature of 23 ° C. and a humidity of 50%.
[Measurement of total light transmittance] Measured according to JIS K-7105.

(Example 1)
16 g of bisphenoxyethanol full orange glycidyl ether (trade name “BPEF-G” manufactured by Osaka Gas Co., Ltd.) was dissolved in 16 g of tetrahydrofuran to obtain a resin solution. Next, 60 g of 12 g of methoxypolysiloxane (manufactured by Tama Chemical Industry Co., Ltd., trade name “M silicate 51”), 32 g of 3-glycidoxypropyltriethoxysilane, 5 g of 10% by weight aqueous solution of formic acid and 18 g of tetrahydrofuran was stirred. The mixture was refluxed at 3 ° C. for 3 hours, and 1 g of a photocuring agent (manufactured by Asahi Denka Kogyo Co., Ltd., trade name “Adekaoptomer SP-150”) and a resin solution were added to obtain a resin varnish.

This resin varnish is made of E glass (refractive index 1.57) fiber and has a thickness of 50 μm (made by Asahi Schwer, style 1080, cationic silane surface-treated product, E glass fiber used, glass refractive index 1 .57) and the solvent was stripped off in a dryer at 60 ° C. Photocuring was performed using an ultraviolet irradiation device (Ushio Electric Co., Ltd., UVC-1212) at an irradiation dose of 2000 mJ / cm ² . Next, after heating at 100 ° C. for 1 hr, press molding was performed at 150 ° C. for 1 hr to obtain a transparent hybrid sheet having a thickness of 100 μm. The total light transmittance of the hybrid sheet was 90%. A resin varnish was dropped onto a silicon wafer, then applied by spin coating, heated and cured at 150 ° C. for 1 hour to produce a thin film coated piece having a thickness of about 500 nm, and the refractive index was measured. The rate was 1.56.

(Example 2)
8 g of bisphenoxyethanol full orange glycidyl ether (trade name “BPEF-G” manufactured by Osaka Gas Co., Ltd.) was dissolved in 8 g of tetrahydrofuran to obtain a resin solution. Next, 18 g of phenyltrimethoxysilane, 8 g of 3-glycidoxypropyltriethoxysilane, 8 g of 10% by weight aqueous solution of formic acid and 49 g of tetrahydrofuran were refluxed at 60 ° C. for 3 hours with stirring, and a thermosetting agent (Asahi Denka Kogyo Co., Ltd.). 1 g of a product name “Adeka Opton CP-66”) and a resin solution were added to obtain a resin varnish.

  The resin varnish was impregnated into a glass cloth in the same manner as in Example 1, and the solvent was volatilized with a dryer at 60 ° C. Thermosetting was performed by heating at 120 ° C. for 3 hours and press molding at 150 ° C. for 1 hour to obtain a transparent hybrid sheet having a thickness of 100 μm. The total light transmittance of the hybrid sheet measured in the same manner as in Example 1 was 88%, and the refractive index of the hybrid resin was 1.60.

(Example 3)
8 g of bisphenol A-type glycidyl ether (manufactured by Japan Epoxy Resin Co., Ltd., trade name “Epicoat 828”, epoxy equivalent 190 g / eq) was dissolved in 8 g of tetrahydrofuran to obtain a resin solution. Next, 18 g of phenyltrimethoxysilane, 8 g of 3-glycidoxypropyltriethoxysilane, 8 g of 10% by weight aqueous solution of formic acid and 49 g of tetrahydrofuran were refluxed at 60 ° C. for 3 hours with stirring, and a thermosetting agent (Asahi Denka Kogyo Co., Ltd.). 1 g of a product name “Adeka Opton CP-66”) and a resin solution were added to obtain a resin varnish.

  The resin varnish was impregnated into a glass cloth in the same manner as in Example 1, and the solvent was volatilized with a dryer at 60 ° C. Thermosetting was performed by heating at 120 ° C. for 3 hours and press molding at 150 ° C. for 1 hour to obtain a 120 μm thick hybrid sheet. The total light transmittance of the hybrid sheet measured in the same manner as in Example 1 was 85%, and the refractive index of the hybrid resin was 1.53.

(Comparative Example 1)
16 g of bisphenol A-type glycidyl ether (manufactured by Japan Epoxy Resin Co., Ltd., trade name “Epicoat 828”, epoxy equivalent 190 g / eq) was dissolved in 16 g of tetrahydrofuran to obtain a resin solution. Next, 60 g of 12 g of methoxypolysiloxane (manufactured by Tama Chemical Industry Co., Ltd., trade name “M silicate 51”), 32 g of 3-glycidoxypropyltriethoxysilane, 5 g of 10% by weight aqueous solution of formic acid and 18 g of tetrahydrofuran was stirred. The mixture was refluxed at 3 ° C. for 3 hours, and 1 g of a photocuring agent (manufactured by Asahi Denka Kogyo Co., Ltd., trade name “Adekaoptomer SP-150”) and a resin solution were added to obtain a resin varnish.
The resin varnish was impregnated into a glass cloth in the same manner as in Example 1, and the solvent was volatilized with a dryer at 60 ° C. Thermosetting was performed by heating at 120 ° C. for 3 hours and press molding at 150 ° C. for 1 hour to obtain a 120 μm thick hybrid sheet. The total light transmittance of the hybrid sheet measured in the same manner as in Example 1 was 75%, and the refractive index of the hybrid resin was 1.47.

  Since the hybrid sheet of the present invention is excellent in strength, rigidity, toughness, transparency, heat resistance, rigidity, gas barrier properties, thermal expansion coefficient, birefringence, etc., as a transparent substrate for touch panels and dye-sensitized solar cells Is preferred.

Claims (6)

In a hybrid sheet obtained by impregnating and curing a glass cloth with an organic-inorganic hybrid resin having a metal alkoxide and a thermosetting resin as constituent elements, the refractive index (n ₁ ) of the organic-inorganic hybrid resin after curing and the The refractive index (n ₂ ) of the glass constituting the glass cloth is
n ₂ −0.05 ≦ n ₁ ≦ n ₂ +0.05
A transparent hybrid sheet having a thickness of 50 μm or more.   The transparent hybrid sheet according to claim 1, wherein the metal alkoxide is at least one selected from silane alkoxide, zirconium alkoxide, titanium alkoxide, and aluminum alkoxide. The metal alkoxide is a silane alkoxide, and a silane compound represented by the following general formula (1) and / or a partial condensate thereof, or a reactive silane compound represented by the following general formula (2): The transparent hybrid sheet according to claim 1, which is a mixture.
^{_{(R 1) x -Si- (OR}} 2) 4-x (1)
^{_{(R 3) y -Si- (OR}} 2) 4-y (2)
In the formula, R ¹ is CH ₃ or C ₆ H ₅ , R ² is CH ₃ or C ₂ H ₅ , x is 0 to 2, and R ³ is a functional group that reacts with the thermosetting resin to form a bond. Organic chain, y is 1 or 2 The organic-inorganic hybrid resin contains at least one kind of resin containing a fluorene group and / or at least one kind of metal alkoxide represented by the following general formula (3). The transparent hybrid sheet described in 1.
_{(C 6 H 5) z -Si-} (OR 2) 4-z (3)
In the formula, R ² is CH ₃ or C ₂ H ₅ , z is 1 or 2   The transparent hybrid sheet according to claim 4, wherein the resin containing a fluorene group is a fluorene group-containing epoxy resin.   The transparent hybrid sheet according to claim 1, wherein the glass cloth is E glass.