JP2009244757A - Transparent substrate - Google Patents

Abstract

Disclosed is a transparent substrate having high surface smoothness, good weather resistance, and capable of reducing the occurrence of discoloration.
SOLUTION: A high refractive index resin having a higher refractive index than glass fiber and a low refractive index resin having a lower refractive index than glass fiber are mixed, and the refractive index is adjusted to approximate the refractive index of glass fiber. The transparent laminated board 1 produced by impregnating and hardening | curing a resin composition to a glass fiber base material is provided. A transparent smoothing layer 2 for forming a smooth surface is formed on the transparent laminate 1, and the smoothing layer 2 contains a material having a function of absorbing ultraviolet light. The smoothing layer 2 can fill the unevenness of the transparent laminated plate 1 and make it flat, and the surface smoothness can be improved. Moreover, it can suppress that ultraviolet light acts on the smoothing layer 2 and the transparent laminated board 1 with the material which has the function which absorbs the ultraviolet light contained in the smoothing layer 2, and reduces generation | occurrence | production of discoloration. Can do.
[Selection] Figure 1

Description

  The present invention relates to a transparent substrate used for a liquid crystal display or the like.

  A transparent substrate formed of a transparent laminated plate has been studied as a material to replace a glass plate in flat panel displays such as a liquid crystal display, a plasma display, and an EL display (for example, Patent Document 1).

  As an example of such a transparent laminate used as a transparent substrate, a prepreg is prepared by impregnating a substrate made of glass fiber such as glass cloth with a transparent thermosetting resin having a refractive index similar to that of glass fiber. What was produced by heat-press-molding can be mentioned. An epoxy resin is generally used as the transparent thermosetting resin. In order to approximate the refractive index of the resin to the refractive index of the glass fiber, an epoxy resin having a higher refractive index than the glass fiber and a refractive index higher than that of the glass fiber are used. A resin composition is used in which a small epoxy resin is mixed and the mixing ratio is adjusted so that the refractive index approximates the refractive index of the glass fiber. Thus, by combining the refractive index of the glass fiber of the base material and the matrix resin, the refraction of light in the transparent laminate can be suppressed and used as a transparent substrate of a display excellent in visibility.

FIG. 2 shows an example of a schematic configuration of a liquid crystal display manufactured using a transparent substrate A formed of such a transparent laminated plate. A pair of transparent substrates A are arranged in parallel, and the space between the transparent substrates A is shown. The drive element 10 is mounted on the board. The drive element 10 includes a pixel electrode 11 and TFT 12 provided on one transparent substrate A, a common electrode 13 provided on the other transparent substrate A, and liquid crystal molecules 14 filled between the transparent substrates A. It is what is done.
JP 2004-307851 A

  In the liquid crystal display as described above, if the distance between the transparent substrates A arranged opposite to each other is non-uniform, the thickness of the liquid crystal molecules 14 filled becomes non-uniform, and the orientation of the liquid crystal molecules 14 May be partially disturbed and light scattering may occur.

  However, since the transparent substrate A is formed by a transparent laminated plate prepared by impregnating and curing a resin on a glass base material, it is difficult to form a surface with high smoothness like a glass substrate. The unevenness of the glass substrate formed by cloth or the like appears on the surface, and the smoothness tends to be lowered. Accordingly, when such a transparent substrate A is used as a substrate for a liquid crystal display, the interval between the transparent substrates A arranged opposite to each other becomes non-uniform, and the alignment of the liquid crystal molecules 14 that are filled is disturbed. There is a problem that scattering may occur and a clear image may not be obtained.

  In the case of a liquid crystal display, the light from the backlight is applied to the transparent substrate A, but the ultraviolet light contained in the light from the backlight acts on the transparent substrate A. And since the transparent substrate A is formed by a transparent laminated plate prepared by impregnating and curing a resin on a glass substrate, the resin is deteriorated by ultraviolet light and discolored, and the transparent substrate A is discolored and is transparent. There was a problem that there was a risk of lowering.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a transparent substrate having high surface smoothness, good weather resistance, and capable of reducing the occurrence of discoloration. .

  The transparent substrate according to the present invention is a mixture of a high refractive index resin having a refractive index larger than that of glass fiber and a low refractive index resin having a refractive index smaller than that of glass fiber so that the refractive index approximates that of glass fiber. A transparent smoothing layer 2 is formed on the transparent laminate 1 for smooth formation of the surface. The transparent laminate 1 is prepared by impregnating and curing a glass fiber base material with a resin composition adjusted to In addition, the smoothing layer 2 contains a material having a function of absorbing ultraviolet light.

  According to this invention, the unevenness of the transparent laminate 1 can be filled with the smoothing layer 2 to make it flat, the surface smoothness can be improved, and the ultraviolet contained in the smoothing layer 2. The material having the function of absorbing light can suppress the ultraviolet light from acting on the smoothing layer 2 and the transparent laminated plate 1, and weather resistance using the smoothing layer 2 for smoothing the surface. And the occurrence of discoloration can be reduced.

  In the present invention, the material having the function of absorbing ultraviolet light is characterized by being at least one fine particle selected from titanium oxide, zinc oxide, and cerium oxide having an average particle diameter of 100 nm or less. The ultraviolet light absorption performance of the smoothing layer 2 is enhanced, and the effect of reducing the occurrence of discoloration can be obtained.

  In the present invention, the material having the function of absorbing ultraviolet light is at least one organic compound selected from benzophenone, benzotriazole, triazine, hindered amine, salicylate, and benzenethiol metal complexes. The ultraviolet light absorption performance of the smoothing layer 2 is enhanced, and a high effect of reducing the occurrence of discoloration can be obtained.

  Further, in the present invention, the smoothing layer 2 is characterized in that the transmission of light having a wavelength of 405 nm or less is cut by 85% or more. A high effect of reducing the occurrence can be obtained.

  In the present invention, the smoothing layer 2 is a resin layer formed by coating the transparent laminate 1 with a resin coating agent, and is coated with a resin coating agent. The smoothing layer 2 can be easily formed.

  In the present invention, the smoothing layer 2 is formed by sticking a film to the transparent laminate 1, and the smoothing layer 2 can be easily formed by attaching the film. It can be formed.

  In the present invention, the difference in refractive index between the transparent laminate 1 and the smoothing layer 2 is 0.01 or less.

  According to the present invention, it is possible to obtain a transparent substrate having high transparency by suppressing light refraction and total reflection between the transparent laminate 1 and the smoothing layer 2.

  Moreover, in this invention, cyanate ester resin is used as high refractive index resin of the resin composition which produces the transparent laminated board 1. It is characterized by the above-mentioned.

  According to this invention, the glass transition temperature of resin of the transparent laminated board 1 can be raised with cyanate ester resin, and the transparent substrate excellent in heat resistance can be obtained.

  According to the present invention, the smoothing layer 2 can fill the unevenness of the transparent laminate 1 and level it, and the surface smoothness of the transparent laminate can be improved. Moreover, the material having a function of absorbing the ultraviolet light contained in the smoothing layer 2 can suppress the ultraviolet light from acting on the smoothing layer 2 and the transparent laminated plate 1, and smoothes the surface. The smoothing layer 2 can be used to improve weather resistance and reduce the occurrence of discoloration on the transparent substrate.

  Hereinafter, the best mode for carrying out the present invention will be described.

  First, the transparent laminated board used in this invention is demonstrated. This transparent laminate is adjusted so that the refractive index approximates the refractive index of the glass fiber by mixing a high refractive index resin having a higher refractive index than that of the glass fiber and a low refractive index resin having a lower refractive index than that of the glass fiber. The resin composition prepared is impregnated into a glass fiber substrate and cured.

  It is preferable to use a cyanate ester resin as a resin having a higher refractive index than the glass fiber. The cyanate ester resin is obtained by polymerization of a cyanate ester compound having two or more cyanate groups in one molecule by generating a triazine ring by trimerization. Examples of the cyanate ester compound include 2,2-bis ( Aromatic cyanate ester compounds such as 4-cyanatophenyl) propane, bis (3,5-dimethyl-4-cyanatophenyl) methane, 2,2-bis (4-cyanatophenyl) ethane, and derivatives thereof Can be used. These may be used alone or in combination of a plurality of types. This cyanate ester resin has a rigid molecular skeleton, and therefore imparts a high glass transition temperature to the cured product. Further, since cyanate ester resin is solid at normal temperature, it becomes easy to dry by touch when preparing a prepreg by impregnating a resin composition into a glass fiber substrate and drying it as described later. The prepreg is easy to handle.

  Here, when the refractive index of the glass fiber is, for example, 1.562, the cyanate ester resin used as the high refractive index resin preferably has a refractive index of around 1.6. When the refractive index of the glass fiber is n, n + 0 It is desirable that it is in the range of 0.03 to n + 0.06. In the present invention, the refractive index of the resin refers to the refractive index in the state of the cured resin, and is a value tested by ASTM D542.

  On the other hand, as the resin having a lower refractive index than the glass fiber, any epoxy resin can be used as long as it has a low refractive index, but it is preferable to use a hydrogenated bisphenol type epoxy resin. When the refractive index of the glass fiber is 1.562, for example, the low refractive index epoxy resin preferably has a refractive index of around 1.5, where n−0.04, where n is the refractive index of the glass fiber. It is desirable to be in the range of ˜n−0.08.

  In the low refractive index hydrogenated bisphenol type epoxy resin, as the bisphenol type, bisphenol F type, bisphenol S type and the like can be used in addition to the bisphenol A type.

  Further, as the hydrogenated bisphenol type epoxy resin having a low refractive index, it is preferable to use a solid type hydrogenated bisphenol type epoxy resin that is solid at room temperature. Liquid type hydrogenated bisphenol type epoxy resin that is liquid at room temperature can be used, but when preparing the prepreg, it can only be dried to a sticky state with the touch, and the prepreg is easy to handle. Since it becomes worse, it is preferable to use a solid-type hydrogenated bisphenol-type epoxy resin. Furthermore, it is possible to use other than the hydrogenated bisphenol type epoxy resin as the low refractive index epoxy resin. For example, an epoxy resin containing 1,2-epoxy-4- (2-oxiranyl) cyclohexane is used in combination. be able to. This epoxy resin is used in combination to finely adjust the refractive index, and is an optimal resin for facilitating the production of a transparent laminate because it is solid at room temperature.

  Then, the above-described high refractive index cyanate ester resin is mixed with an epoxy resin such as a low refractive index hydrogenated bisphenol type epoxy resin to prepare and use a resin composition that approximates the refractive index of glass fiber. is there. The mixing ratio of the high refractive index cyanate ester resin and the low refractive index epoxy resin is arbitrarily adjusted so as to approximate the refractive index of the glass fiber. Here, it is desirable that the refractive index of the resin composition be as close as possible to the refractive index of the glass fiber. It is preferable to do this.

  The resin composition is preferably prepared such that the cured resin has a glass transition temperature (Tg) of 170 ° C. or higher. When the glass transition temperature is 170 ° C. or higher, the heat resistance of the transparent laminate can be increased. The upper limit of the glass transition temperature is not particularly set, but practically about 280 ° C. is the upper limit of the glass transition temperature. The glass transition temperature can be adjusted by changing the blending ratio of the cyanate ester resin in the resin composition, and depends on the type of low refractive index resin used together. If the cyanate ester resin is about 30% by mass or more in the resin component, the glass transition temperature of the resin composition can be adjusted to 170 ° C. or more. Here, in this invention, a glass transition temperature is the value measured based on JISC6481 TMA method.

  Furthermore, a curing initiator (curing agent) can be blended in the resin composition. An organic metal salt can be used as the curing initiator. Examples of the organic metal salt include salts of an organic acid such as octanoic acid, stearic acid, acetylacetonate, naphthenic acid, and salicylic acid with a metal such as Zn, Cu, and Fe. These may be used alone or in combination of two or more. Among them, zinc octoate is preferable. By using zinc octoate as the curing initiator, the glass transition temperature of the cured resin can be increased. The content of the organic metal salt such as zinc octoate in the resin composition is not particularly limited, but is preferably in the range of 0.01 to 0.1 PHR.

  A cationic curing agent can also be used as the curing initiator. Thus, by using a cationic curing agent, the transparency of the resin can be enhanced. The cationic curing agent is not particularly limited, and aromatic sulfonium salts, aromatic iodonium salts, ammonium salts, aluminum chelates, boron trifluoride amine complexes, and the like can be used. The content of the cationic curing agent in the resin composition is not particularly limited, but is preferably in the range of 0.2 to 3.0 PHR.

  Further, a curing catalyst such as a tertiary amine such as triethylamine or triethanolamine, 2-ethyl-4-imidazole, 4-methylimidazole, 2-ethyl-4-methyl-imidazole (2E4MZ) may be used as a curing initiator. it can. The content of the curing catalyst in the resin composition is not particularly limited, but is preferably in the range of 0.5 to 5 PHR.

  As described above, a resin composition can be prepared by blending an epoxy resin such as a high refractive index cyanate ester resin, a low refractive index hydrogenated bisphenol type epoxy resin, and a curing initiator. This resin composition is used as a resin varnish after being dissolved or dispersed in a solvent as required. The solvent is not particularly limited, but benzene, toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, acetone, methanol, ethanol, isopropyl alcohol, 2-butanol, ethyl acetate, butyl acetate, propylene glycol monomethyl ether, Propylene glycol monomethyl ether acetate, diacetone alcohol, N, N′-dimethylacetamide and the like can be used.

  On the other hand, the glass fiber is preferably E glass or NE glass in view of the effect of increasing the impact resistance of the transparent laminate. E glass is also called non-alkali glass and is a glass that is widely used as a glass fiber for resin reinforcement, and NE glass is NewE glass. Moreover, it is preferable to surface-treat glass fiber with the silane coupling agent normally used as a glass fiber processing agent in order to improve impact resistance. The refractive index of the glass fiber is preferably in the range of 1.55 to 1.57, and more preferably in the range of 1.555 to 1.565. If the refractive index of glass fiber is this range, the transparent laminated board excellent in visibility can be obtained. As the glass fiber base material, a glass fiber woven fabric or non-woven fabric can be used.

  A prepreg can be prepared by impregnating a glass fiber base material with a varnish of a resin composition, heating and drying. The drying conditions are not particularly limited, but a drying temperature of 100 to 160 ° C. and a drying time of 1 to 10 minutes are preferable.

  Next, one or a plurality of the prepregs are stacked and heated and pressed to cure the resin composition, thereby obtaining a transparent laminate. The conditions for the heat and pressure molding are not particularly limited, but a temperature range of 150 to 200 ° C., a pressure of 1 to 4 MPa, and a time of 10 to 120 minutes are preferable.

  In the transparent laminate obtained as described above, a resin matrix formed by polymerizing an epoxy resin such as a high refractive index cyanate ester resin and a low refractive index hydrogenated bisphenol type epoxy resin is a cyanate ester resin. By containing the glass, a glass transition temperature is high, and a transparent laminate having excellent heat resistance can be obtained. In addition, epoxy resins such as cyanate ester resin and hydrogenated bisphenol type epoxy resin are all excellent in transparency, and a transparent laminate having high transparency can be obtained. In this transparent laminated plate, the glass fiber base material content is preferably in the range of 25 to 65% by mass, and within this range, high impact resistance can be obtained due to the reinforcing effect of the glass fiber. Sufficient transparency can be obtained.

  Here, as a glass fiber base material, in order to obtain high transparency, it is preferable to use a plurality of thinly laminated ones. Specifically, it is preferable to use a glass fiber substrate having a thickness of 50 μm or less and to use two or more glass fiber substrates having a thickness of 50 μm or less. Although the minimum of the thickness of a glass fiber base material is not specifically limited, About 10 micrometers is a practical minimum. The number of glass fiber substrates is not particularly limited, but about 20 is the practical upper limit. When producing a transparent laminate using a plurality of glass fiber base materials in this way, each glass fiber base material is impregnated with a resin composition and dried to produce a prepreg, and a plurality of the prepregs are stacked and heated. A transparent laminate can be obtained by pressure molding, but a prepreg is produced by impregnating and drying a resin composition in a state where a plurality of glass fiber base materials are stacked, and this prepreg is heated and pressure-molded. A transparent laminate may be obtained.

  And the transparent substrate A which concerns on this invention as shown in FIG. 1 can be obtained by forming the transparent smoothing layer 2 on the surface of the transparent laminated board 1 produced as mentioned above.

  Although it does not specifically limit as a material which forms the smoothing layer 2, For example, by apply | coating a resin coating agent to the surface of the transparent laminated board 1, and making it dry and harden | cure, the smoothing layer 2 is used as a resin layer. Can be formed. As the resin of this resin coating agent, for example, any resin such as acrylic resin, urethane resin, epoxy resin, polyvinyl alcohol, ethylene vinyl alcohol copolymer, polyamide, and cellulose can be used.

  The coating agent can be applied using an appropriate method such as spraying, gravure printing, roll coating, spin coating, or bar coating. Thus, when forming the smoothing layer 2 by application | coating of a resin coating agent, the film thickness of the smoothing layer 2 is although it does not specifically limit, The range of 1-10 micrometers is preferable.

  Moreover, the smoothing layer 2 can also be formed with the resin film produced by extrusion molding etc. In this case, the smoothing layer 2 can be formed by laminating a resin film on the surface of the transparent laminate 1 and attaching it. The resin film can be attached to the transparent laminate 1 using an adhesive or a pressure-sensitive adhesive. Further, after impregnating and drying the glass fiber base material with the resin composition as described above to produce a semi-cured prepreg, a resin film is layered on the prepreg, and the resin of the prepreg is formed by heating and pressing. At the same time as making the transparent laminate 1 by curing, a resin film may be laminated and integrated on the transparent laminate 1.

  As the resin of the resin film, for example, an arbitrary resin such as an acrylic resin, polyester, or fluorine resin can be used. Thus, when forming the smoothing layer 2 with a resin film, the film thickness of the smoothing layer 2 is not specifically limited, However, The range of 25-200 micrometers is preferable.

  In the present invention, the smoothing layer 2 contains a material having a function of absorbing ultraviolet light. When the smoothing layer 2 is formed by coating with a resin coating agent, a material having a function of absorbing ultraviolet light is contained by adding a material having a function of absorbing ultraviolet light to the resin coating agent. The smoothing layer 2 can be formed, and when the smoothing layer 2 is formed by attaching a resin film, a resin film prepared by kneading a material having a function of absorbing ultraviolet light is used. It is what is used.

  As a material having a function of absorbing ultraviolet light, for example, particles selected from titanium oxide, zinc oxide, and cerium oxide can be used. These may be used alone or in combination of two or more. These particles have high ultraviolet light absorption performance, and fine particles having an average particle diameter of 100 nm or less are used. When the average particle diameter exceeds 100 nm, the transparency of the smoothing layer 2 is lowered, and the light transmittance of the transparent substrate A may be lowered. The lower limit of the average particle diameter is not particularly set, but about 5 nm is practically the lower limit of the average particle diameter. In the present invention, the average particle diameter is a value measured by a laser diffraction / scattering method.

  When fine particles selected from these titanium oxide, zinc oxide, and cerium oxide are used as a material having a function of absorbing ultraviolet light, the content in the smoothing layer 2 is not particularly limited, but the smoothing layer It is desirable that the amount be in the range of 5 to 50 parts by mass with respect to 100 parts by mass of the resin solid content of 2.

  As a material having a function of absorbing ultraviolet light, an organic compound selected from benzophenone-based, benzotriazole-based, triazine-based, hindered amine-based, salicylate-based, and benzenethiol metal complexes can also be used. These organic compounds can be used alone or in combination of two or more.

  These organic compounds are generally used as ultraviolet absorbers and have high ultraviolet light absorption performance. Examples of these organic compounds include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, 4-dodecyloxy-2-hydroxybenzophenone. 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2,2 ', 4,4'-tetrahydroxybenzophenone, 2-hydroxy-4-methoxy- 2'-carboxybenzophenone, 2-hydroxy-4-oxybenzylbenzophenone, 2-hydroxy-4-chlorobenzophenone, 2-hydroxy-5-chlorobenzophenone, 2-hydroxy-4-methoxy-4'-methylbenzophenone, 2- Hydroxy 4-n-F script carboxymethyl benzophenone, 2-hydroxy-3,6-dichloro-4-ethoxy-benzophenone, 2-hydroxy-4- (2-hydroxy-3-methyl-acryloxy) propoxy benzophenone.

  Examples of the benzotriazole type include 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-3′-t-butyl-5′-methylphenyl) benzotriazole, 2- ( 2'-hydroxy-5'-t-octylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-t-butyl-5'-amylphenyl) benzotriazole, 2- (2' -Hydroxy-3 ', 5-di-t-butylphenyl) benzotriazole, 2- (2'-hydroxy-3'-t-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2 '-Hydroxy-3', 5'-di-t-butylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3 ', 5'-diphenylphenyl) benzotria Such Lumpur, and the like.

  Examples of triazines include 2- (4,6-diphenyl-1,3,5-triazin-2-yl) -5-[(hexyl) oxy] -phenol, 2- [4,6-bis (2,4 -Dimethylphenyl) -1,3,5-triazin-2-yl] -5- (octyloxy) phenol, for example, triazines such as triaryltriazines such as UV1164 (manufactured by Cytec), TINUVIN1577 FF (manufactured by Ciba Specialty Chemicals) And the like.

  Examples of salicylates include phenyl salicylate, p-octylphenyl salicylate, pt-butylphenyl salicylate, carboxyphenyl salicylate, methylphenyl salicylate, dodecylphenyl salicylate and the like.

  When these organic compounds are used as materials having a function of absorbing ultraviolet light, the content in the smoothing layer 2 is not particularly limited, but the resin solid content of the smoothing layer 2 is 100 parts by mass. The range of 0.01 to 10 parts by mass is desirable, and the range of 0.1 to 3 parts by mass is more preferable.

  In the transparent substrate A formed by laminating the smoothing layer 2 on the surface of the transparent laminate 1 as described above, the smoothing layer 2 is in a state where the unevenness of the transparent laminate 1 is filled and flattened. The transparent substrate A which is formed and has high smoothness can be obtained by the smoothing layer 2. In this way, by increasing the smoothness of the surface of the transparent substrate A, the transparent substrate A can be filled with the liquid crystal molecules 14 of the driving element 10 by arranging the pair of transparent substrates A in parallel as shown in FIG. The interval between the electrodes can be set to a uniform size, the liquid crystal molecules 14 can be prevented from being disturbed in alignment, and light scattering can be prevented from occurring. Can be produced.

  The smoothness of the surface of the transparent substrate A formed by the smoothing layer 2 is preferably such that the surface roughness Ra is 30 μm or less. When the surface roughness Ra is 30 μm or less, the distance between the transparent substrates A can be set more uniformly, and the liquid crystal molecules 14 can be more reliably prevented from being disturbed in alignment, and light scattering occurs. It is possible to prevent this. The smaller the surface roughness Ra, the better. The lower limit is not set. Here, the surface roughness Ra is an arithmetic average roughness defined by JIS B0601 (1994).

  The smoothing layer 2 contains a material having a function of absorbing ultraviolet light as described above. Therefore, of the light incident on the transparent substrate A through the smoothing layer 2, the ultraviolet light is absorbed in the smoothing layer 2 and cut. For this reason, it is possible to prevent the resin forming the smoothing layer 2 and the resin forming the transparent laminate 1 from being deteriorated and discolored by the action of ultraviolet light. Thus, the weather resistance of the transparent substrate A can be improved by using the smoothing layer 2 for increasing the smoothness of the surface of the transparent substrate A, and discoloration occurs in the transparent substrate A. It is possible to prevent the transparency of the transparent substrate A from being lowered.

  At this time, the smoothing layer 2 desirably has a performance of absorbing 85% or more of light having a wavelength of 405 nm or less and cutting the transmission of light having this wavelength by 85% or more. By cutting 85% or more of light having a wavelength of 405 nm or less in the ultraviolet region with the smoothing layer 2, the color change of the transparent substrate A can be effectively prevented and the transparency can be maintained. By adjusting the type and content of the material having the function of absorbing the ultraviolet light contained in the smoothing layer 2, the film thickness of the smoothing layer 2, etc., 85% or more of light having a wavelength of 405 nm or less is cut. The smoothing layer 2 having performance can be formed. The higher the cut rate of light having a wavelength of 405 nm or less, the more preferable, and no upper limit is set.

  The difference in refractive index between the transparent laminate 1 and the transparent smoothing layer 2 is preferably 0.01 or less. The refractive index difference between the transparent laminated plate 1 and the smoothing layer 2 is as small as 0.01 or less, thereby suppressing the light from being refracted or totally reflected between the transparent laminated plate 1 and the smoothing layer 2. And a transparent substrate A having high light transmittance and high transparency can be obtained. This refractive index difference is preferably as small as possible, and ideally the refractive index difference is zero.

  Next, the present invention will be specifically described with reference to examples.

Example 1
As a high refractive index resin, solid cyanate ester resin (“BADCy” manufactured by Lonza, 2,2-bis (4-cyanatophenyl) propane: refractive index 1.59) is 52 parts by mass, as a low refractive index resin. 48 parts by mass of an epoxy resin containing solid 1,2-epoxy-4- (2-oxiranyl) cyclohexane (“EHPE3150” manufactured by Daicel Chemical Industries, Ltd .: refractive index 1.51) was added, and further curing started 0.02 parts by mass of zinc octoate was blended as an agent, 50 parts by mass of toluene and 50 parts by mass of methyl ethyl ketone were added thereto, and the mixture was stirred and dissolved at a temperature of 70 ° C. to prepare a varnish of the resin composition. The refractive index of the cured product of this resin composition was 1.56.

  Next, a glass fiber cloth having a thickness of 25 μm (Asahi Kasei Electronics Co., Ltd., product number “1037”, E glass, refractive index 1.562) is impregnated with the varnish of the above resin composition and heated at 150 ° C. for 5 minutes. Thus, the solvent was removed and the resin was semi-cured to prepare a prepreg.

  Then, two sheets of this prepreg are stacked, sandwiched between release-molded glass plates, set in a press machine, and heated and pressed under conditions of 170 ° C., 2 MPa, 15 minutes, whereby the resin content is 63% by mass. A transparent laminate 1 having a thickness of 80 μm was obtained.

  Meanwhile, 20 parts by mass of zinc oxide fine particles (refractive index 1.95) having an average particle diameter of 0.02 μm are added to 100 parts by mass of an ultraviolet curable acrylic resin (“HC202” manufactured by Adeka Corporation, refractive index: 1.49). The mixture was mixed and dispersed for 30 minutes by a circulating bead mill using zirconia beads having a diameter of 0.1 mm. The coating agent was obtained by removing zirconia beads from the obtained dispersion and further adding 1 part by mass of a near ultraviolet curing agent (“Darocur TPO” manufactured by Ciba Specialty Chemicals Co., Ltd.).

  Then, the transparent laminated plate 1 is attached to a lead film and supplied, and a coating agent is applied to the surface of the transparent laminated plate 1 by a gravure coating method using a gravure with a line number of 60 / inch. The film is coated under the conditions of 35 ° C for 12 seconds, 60 ° C for 12 seconds, 120 ° C for 12 seconds, 130 ° C for 12 seconds, and then cured by irradiating with ultraviolet rays to obtain a 6 μm thick smooth A transparent substrate A on which the chemical layer 2 was formed was obtained.

(Example 2)
UV curable acrylic resin (“HC202” manufactured by Adeka Co., Ltd., refractive index: 1.49) and 100 parts by mass of a benzotriazole ultraviolet absorber (“Tinuvin 900” manufactured by Ciba Specialty Chemicals Co., Ltd.) 1 A coating agent was obtained by adding 1 part by mass of a near ultraviolet curing agent (“Darocur TPO” manufactured by Ciba Specialty Chemicals Co., Ltd.).

  And the transparent laminated board 1 produced in Example 1 is affixed on a lead film, and is supplied, A coating agent is applied to the surface of this transparent laminated board 1 by the gravure coating method using a gravure with 60 lines / inch. The film was coated at a transfer speed of 5 m / min, dried at 35 ° C. for 12 seconds, 60 ° C. for 12 seconds, 120 ° C. for 12 seconds, and 130 ° C. for 12 seconds, and then cured by irradiating with ultraviolet rays to obtain a thickness. A transparent substrate A on which a smoothing layer 2 having a thickness of 6 μm was formed was obtained.

(Example 3)
An acrylic pressure-sensitive adhesive (“SK Dyne 1850G”, glass transition temperature: −40 ° C., viscosity: 4 Pa · S, manufactured by Soken Chemical Co., Ltd.) diluted with a solvent so that the solid content was 20% by mass was produced in Example 1. A transparent pressure-sensitive adhesive layer having a thickness of 25 μm was formed on the surface of the transparent laminate 1 by applying a bar coater to a dry film thickness of 25 μm and drying in an oven at 80 ° C. for 5 minutes. A transparent laminate is obtained by laminating a photocatalyst-containing acrylic resin film ("Lclean DUO" manufactured by Kimoto Co., Ltd.) having a thickness of 100 µm and containing titanium oxide fine particles having an average particle diameter of 3 µm on the transparent adhesive layer. A smoothing layer 2 was formed on 1 to obtain a transparent substrate A.

Example 4
A transparent adhesive layer with a thickness of 25 μm was formed on the surface of the transparent laminate 1 produced in Example 1 in the same manner as in Example 3. Then, a smoothing layer 2 is formed on the transparent laminate 1 by laminating a 100 μm-thick UV absorber-containing PET film (“A1459” manufactured by Toyobo Co., Ltd.) on the transparent adhesive layer, A transparent substrate A was obtained.

(Example 5)
Two prepregs prepared in Example 1 are stacked, and a weather-resistant fluorine-based alloy film based on polyvinylidene fluoride (“DENKA DX film 14S0250” manufactured by Denki Kagaku Kogyo Co., Ltd.) is brought into contact with this prepreg. I piled up like this. Then, this is sandwiched between mirror-finished stainless steel plates that have been subjected to mold release treatment, and is heated and pressed under conditions of 170 ° C., 2 MPa, 15 minutes, thereby forming a resin content of 63% by mass and a thickness of 80 μm. A smoothing layer 2 was formed on one side of the laminate 1 to obtain a transparent substrate A.

(Example 6)
Into the varnish of the resin composition prepared in Example 1, 1 part by mass of a benzotriazole-based ultraviolet absorber (“Tinubin 900” manufactured by Ciba Specialty Chemicals Co., Ltd.) is added to 100 parts by mass of the resin content. A coating agent was obtained.

  By coating this coating agent on the transparent laminate 1 in the same manner as in Example 1, a transparent substrate A on which the smoothing layer 2 having a thickness of 6 μm was formed was obtained.

(Comparative Example 1)
In Example 1, a smoothing layer 2 having a thickness of 6 μm was formed by using a coating agent containing no zinc oxide fine particles as a coating agent and applying this coating agent to the transparent laminate 1 in the same manner as in Example 1. A transparent substrate A was obtained.

  In the above Examples 1 to 6 and Comparative Example 1, the ultraviolet transmittance of the smoothing layer 2 (the transmittance of light having a wavelength of 405 nm or less), the surface roughness Ra of the surface on which the smoothing layer 2 is formed, the transparent substrate A The transparency of the transparent substrate A, the weather resistance of the transparent substrate A, the refractive index of the transparent laminate 1 and the smoothing layer 2, and the refractive index difference between the two were determined. The results are shown in Table 1.

  The measurement of the ultraviolet transmittance was performed by measuring the transmittance at a wavelength of 405 nm using a Hitachi spectrophotometer U-4100.

  The surface roughness Ra is measured by measuring three points on the surface irregularities in the vertical, horizontal and 45 ° bias directions using a stylus type surface roughness meter “SURFCOM 130A” manufactured by Tokyo Seimitsu Co., Ltd. The average value of the measured values in total of 9 points was taken as the Ra value.

  The evaluation of transparency was performed by measuring the haze value using a haze meter “NDH2000” manufactured by Nippon Denshoku Industries Co., Ltd. in accordance with JIS-K7136.

  Evaluation of the weather resistance was performed in accordance with JIS K 5400 9-8 using a carbon arc sunshine weather meter (Suga Test Instruments Co., Ltd. “WEL-SUN-HCT”) for 1000 hrs. The color difference ΔE (JIS Z 8730) was measured.

  As can be seen from Table 1, each example provided with a smoothing layer containing a material having a function of absorbing ultraviolet light had high surface smoothness and good weather resistance.

It is the schematic which shows an example of embodiment of this invention. It is a figure which shows schematic structure of a liquid crystal display.

Explanation of symbols

1 Transparent laminate 2 Smoothing layer

Claims (8)

  A resin composition prepared by mixing a high refractive index resin having a refractive index higher than that of glass fiber and a low refractive index resin having a refractive index lower than that of glass fiber so that the refractive index approximates the refractive index of glass fiber. A transparent laminated plate produced by impregnating and curing a glass fiber substrate is formed, and a transparent smoothing layer for forming a smooth surface is formed on the transparent laminated plate. A transparent substrate containing a material having a function of absorbing light.   2. The transparent substrate according to claim 1, wherein the material having a function of absorbing ultraviolet light is at least one kind of fine particles selected from titanium oxide, zinc oxide and cerium oxide having an average particle diameter of 100 nm or less.   2. The material having a function of absorbing ultraviolet light is at least one organic compound selected from benzophenone, benzotriazole, triazine, hindered amine, salicylate, and benzenethiol metal complexes. The transparent substrate as described in 1.   The transparent substrate according to any one of claims 1 to 3, wherein the smoothing layer cuts the transmission of light having a wavelength of 405 nm or less by 85% or more.   The transparent substrate according to any one of claims 1 to 4, wherein the smoothing layer is a resin layer formed by coating a transparent laminate with a resin coating agent.   6. The transparent substrate according to claim 1, wherein the smoothing layer is formed by attaching a film to the transparent laminate.   The transparent substrate according to any one of claims 1 to 6, wherein a difference in refractive index between the transparent laminate and the smoothing layer is 0.01 or less.   The transparent substrate according to any one of claims 1 to 7, wherein a cyanate ester resin is used as a high refractive index resin of a resin composition for producing a transparent laminate.

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