JP2007045951A - Method for producing transparent substrate plate, transparent substrate plate and electronic device equipped with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a transparent substrate plate, capable of improving the smoothness of its surface, a transparent substrate plate and an electronic device equipped with the same. <P>SOLUTION: This method for producing the transparent substrate plate used for the electronic device is provided by performing a loading process of loading an uncured resin material containing an epoxy resin expressed by formula (1) and a cationic curing catalyst on a sheet-formed substrate material and a curing process of curing the resin material to form the transparent core substrate plate continuously. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a transparent substrate manufacturing method, a transparent substrate, and an electronic device including the same.

  Conventionally, a glass substrate has been used as a transparent substrate of an electronic device for a flat display or the like. However, since glass substrates have drawbacks such as being thick and easy to break, studies have been made to use a thin, lightweight and flexible resin substrate.

As a method for producing such a resin substrate, for example, glass fiber is arranged on a flat plate mold or an endless belt, and after applying a liquid epoxy resin on the glass fiber, the epoxy resin is made under reduced pressure conditions. A casting method is disclosed in which an epoxy resin substrate containing glass fibers can be obtained if the epoxy resin is cured by impregnation and heat treatment or UV irradiation (see, for example, Patent Document 1).
Moreover, even under normal pressure conditions, there is a method of obtaining an epoxy resin substrate containing glass fibers by immersing glass fibers in a liquid epoxy resin by an impregnation method and curing the epoxy resin in that state. It is disclosed (see Patent Document 1).

  However, since the epoxy resin substrate obtained by such a method cures the epoxy resin in a state in which the glass fiber is immersed in the epoxy resin, the surface smoothness of the epoxy resin substrate may be insufficient.

Japanese Patent Laid-Open No. 2004-51960

The objective of this invention is providing the manufacturing method of the transparent substrate which can improve the smoothness of a surface.
Another object of the present invention is to provide a transparent substrate excellent in smoothness and an electronic device including the same.

（２）前記樹脂材料を前記シート状基材に担持した後に、前記シート状基材の少なくとも片面に支持部材を積層する積層工程を有しているものである上記（１）に記載の透明基板の製造方法。
（３）前記積層工程は、前記担持工程の後、かつ前記硬化工程の前に前記樹脂材料が未硬化の状態で行なわれるものである上記（２）に記載の透明基板の製造方法。
（４）前記積層工程において、前記支持部材によって前記シート状基材の表面から突出する突出物を該シート状基材面側に押圧する上記（２）または（３）に記載の透明基板の製造方法。
（５）前記積層工程の後に、前記支持部材を剥離する剥離工程を有しているものである上記（２）ないし（４）のいずれかに記載の透明基板の製造方法。
（６）前記樹脂材料は、さらに前記エポキシ樹脂の屈折率を調整することが可能な第２成分を含むものである上記（１）ないし（５）のいずれかに記載の透明基板の製造方法。
（７）前記第２成分の屈折率は、前記エポキシ樹脂の屈折率よりも低いものである上記（６）に記載の透明基板の製造方法。
（８）前記第２成分は、前記エポキシ樹脂のエポキシ基と反応可能な官能基を有しているものである上記（６）または（７）に記載の透明基板の製造方法。
（９）前記官能基は、オキセタニル基、エポキシ基、またはビニルエーテル基である上記（８）に記載の透明基板の製造方法。
（１０） 前記樹脂材料の第２成分は、分子構造中にシリケート構造を含むものである上記（６）ないし（９）のいずれかに記載の透明基板の製造方法。
（１１）前記第２成分は、主としてオキセタニル基を持つシルセスキオキサンを含むものである上記（６）ないし（１０）のいずれかに記載の透明基板の製造方法。
（１２）前記シート状基材は、ガラス繊維の集合体で構成されているものである上記（１）ないし（１１）のいずれかに記載の透明基板の製造方法。
（１３）前記ガラス繊維の屈折率と、前記樹脂材料を硬化した後の屈折率との差が、０．０１以下である上記（１２）に記載の透明基板の製造方法。
（１４）前記透明コア基板の少なくとも一方の面に樹脂層を設ける平滑化工程を有しているものである上記（１）ないし（１３）のいずれかに記載の透明基板の製造方法。
（１５）前記透明基板の３０〜１５０℃の平均線膨張係数が４０ｐｐｍ以下である上記（１）ないし（１４）のいずれかに記載の透明基板の製造方法。
（１６）波長５５０ｎｍでの光線透過率が８０％以上である上記（１）ないし（１５）のいずれかに記載の透明基板の製造方法。
（１７）前記透明基板が、表示素子用樹脂基板である上記（１）ないし（１６）のいずれかに記載の透明基板の製造方法。
（１８）上記（１）ないし（１７）のいずれかに記載の透明基板の製造方法によって得られることを特徴とする透明基板。
（１９）上記（１８）に記載の透明基板を備えることを特徴とする電子デバイス。 Such an object is achieved by the present invention described in the following (1) to (19).
(1) A method for producing a transparent substrate for use in an electronic device, the step of carrying an uncured resin material containing an epoxy resin represented by formula (1) and a cationic curing catalyst on a sheet-like base material, A method for producing a transparent substrate, comprising performing a curing step of curing the resin material to continuously form a transparent core substrate.

(2) The transparent substrate according to (1), further including a laminating step of laminating a support member on at least one surface of the sheet-like base material after the resin material is supported on the sheet-like base material. Manufacturing method.
(3) The method for producing a transparent substrate according to (2), wherein the laminating step is performed in the uncured state of the resin material after the supporting step and before the curing step.
(4) In the said lamination process, manufacture of the transparent substrate as described in said (2) or (3) which presses the protrusion which protrudes from the surface of the said sheet-like base material to the said sheet-like base material surface side with the said supporting member. Method.
(5) The method for producing a transparent substrate according to any one of (2) to (4), further including a peeling step for peeling the support member after the laminating step.
(6) The method for producing a transparent substrate according to any one of (1) to (5), wherein the resin material further includes a second component capable of adjusting a refractive index of the epoxy resin.
(7) The method for producing a transparent substrate according to (6), wherein the refractive index of the second component is lower than the refractive index of the epoxy resin.
(8) The method for producing a transparent substrate according to (6) or (7), wherein the second component has a functional group capable of reacting with an epoxy group of the epoxy resin.
(9) The method for producing a transparent substrate according to (8), wherein the functional group is an oxetanyl group, an epoxy group, or a vinyl ether group.
(10) The method for producing a transparent substrate according to any one of (6) to (9), wherein the second component of the resin material includes a silicate structure in a molecular structure.
(11) The method for producing a transparent substrate according to any one of (6) to (10), wherein the second component mainly contains silsesquioxane having an oxetanyl group.
(12) The method for producing a transparent substrate according to any one of (1) to (11), wherein the sheet-like base material is constituted by an aggregate of glass fibers.
(13) The method for producing a transparent substrate according to (12), wherein a difference between a refractive index of the glass fiber and a refractive index after the resin material is cured is 0.01 or less.
(14) The method for producing a transparent substrate according to any one of (1) to (13), further including a smoothing step of providing a resin layer on at least one surface of the transparent core substrate.
(15) The method for producing a transparent substrate according to any one of (1) to (14), wherein an average linear expansion coefficient at 30 to 150 ° C. of the transparent substrate is 40 ppm or less.
(16) The method for producing a transparent substrate according to any one of (1) to (15), wherein the light transmittance at a wavelength of 550 nm is 80% or more.
(17) The method for producing a transparent substrate according to any one of (1) to (16), wherein the transparent substrate is a resin substrate for a display element.
(18) A transparent substrate obtained by the method for producing a transparent substrate according to any one of (1) to (17).
(19) An electronic device comprising the transparent substrate according to (18).

According to the present invention, a transparent substrate with improved surface smoothness and an electronic device including the same can be obtained.
Moreover, when a transparent substrate is obtained through the said lamination process, when using a transparent substrate for the board | substrate for liquid crystal display elements especially, light leakage can be reduced.
Moreover, when the said resin material contains the 2nd component which can adjust the refractive index of the said epoxy resin further, transparency of a transparent substrate can be improved especially.

Hereinafter, a method for producing a transparent substrate according to the present invention will be described in detail based on preferred embodiments shown in the accompanying drawings.
1 to 3 are schematic views illustrating an example of a method for producing a transparent core substrate. FIG. 4 is a cross-sectional view showing an example of a transparent substrate. FIG. 5 is a schematic diagram illustrating an example of the smoothing process. FIG. 6 is a cross-sectional view showing an example of a liquid crystal display element substrate.

As shown in FIG. 1, in the method for producing a transparent core substrate, a sheet-like base material 21 supplied from a sheet-like base material supply unit 2 is transferred to a first impregnation unit 31 by a feed roll 22, and the resin material The primary impregnation (support) is performed, and the resin material is transferred to the second impregnation part 32 to be second impregnated (support) (supporting step 3). Next, the support member 41 is laminated with the lami roll 43 from both sides of the sheet-like substrate 21 impregnated (supported) with the uncured resin material (laminating step 4). Next, the transparent core substrate 1 is continuously manufactured by curing the resin material by passing the sheet-like base material 21 through the dryer 51 (curing step 5).
Hereinafter, each step will be described.

  In the supporting step, a resin material is supported on the sheet-like base material 21. Although the carrying step 3 may be performed once, it is preferably performed separately at a plurality of locations such as a first impregnation portion 31 and a second impregnation portion 32 as shown in FIG. Thereby, it can prevent that a bubble mixes in the sheet-like base material 21. FIG. Examples of the method of supporting the resin material on the sheet-like substrate 21 include a method of impregnation using a kiss roll, a method of immersing in a varnish of the resin material, a method of applying the resin material, and the like.

Further, the primary impregnation may be performed in a single impregnation step, but it is preferable to perform a plurality of impregnation processes as shown in FIG.
In FIG. 1, the resin material is impregnated using a kiss roll. Thereby, the resin material can be penetrated into the sheet-like base material 21. The sheet-like base material 21 is impregnated with the resin material by the first kiss roll 311. And the sheet-like base material 21 is transferred to the 2nd kiss roll 312 using the feed roll 313, and a resin material is impregnated.

  The feed roll 313 may be a fixed roll or a free roll, but is preferably a fixed roll. Thereby, more shear can be applied to the sheet-like base material 21, thereby reducing bubbles generated in the sheet-like base material 21.

  The number of feed rolls 313 is not particularly limited, but is preferably 2 or more, and particularly preferably 3 to 5. When the number of feed rolls 313 is within the above range, the effect of reducing bubbles is particularly excellent.

  Thus, the sheet-like base material 21 that has been firstly impregnated by the primary impregnation unit 31 is transferred to the second impregnation unit 32 to perform the second impregnation. Thereby, the smoothness of the surface can be improved in the subsequent lamination process.

  As shown in FIG. 1, the second impregnation is performed by a method in which the sheet-like base material 21 is immersed in a varnish of a resin material. Thereby, an uncured resin material can be easily applied to the surface of the sheet-like substrate 21.

  The feeding speed of the sheet-like base material 21 in such a supporting process is not particularly limited, and within a range that does not affect the impregnation property of the resin material into the sheet-like base material 21 and the subsequent curing characteristics of the resin material. Can be set.

  Examples of the sheet-like base material 21 used in the present invention include glass fiber base materials such as glass fiber aggregates and glass nonwoven fabrics, which are aggregates of glass fibers, polyamide resin fibers, aromatic polyamide resin fibers, wholly aromatic polyamide resin fibers, and the like. Woven or non-woven fabric mainly composed of polyester resin fibers such as polyamide resin fibers, polyester resin fibers, aromatic polyester resin fibers, wholly aromatic polyester resin fibers, polyimide resin fibers, fluororesin fibers, and cellulose resin fibers Organic fiber base materials such as a paper base material mainly composed of synthetic fiber base material, kraft paper, cotton linter paper, mixed paper of linter and kraft pulp, and the like. Among these, a glass fiber base material is preferable. Thereby, the rigidity of the transparent substrate 8 finally obtained can be improved. Further, the effect of reducing the average linear expansion coefficient of the transparent substrate 8 is also excellent.

  When a glass fiber substrate is used as the sheet-like substrate 21, the refractive index of the glass fiber is not particularly limited, but is preferably 1.4 to 1.6, and particularly preferably 1.5 to 1.55. When the refractive index is within the above range, the difference in refractive index from the epoxy resin can be reduced.

  The resin material impregnated in such a sheet-like base material 21 includes an epoxy resin represented by the formula (1) and a cationic curing catalyst. Thereby, transparency and heat resistance (for example, glass transition temperature) can be improved.

X of the epoxy resin is particularly preferably 2,2-bis (3 ′, 4′-epoxycyclohexyl) propane which is —C (CH ₃ ) ₂ —. Thereby, heat resistance can be improved especially.

The reason why the resin material containing the epoxy resin is excellent in transparency is that the difference in refractive index between the resin material and the material (for example, glass fiber) constituting the sheet-like substrate 21 on which the resin material is supported is relatively small. is there.
The reason for using a cationic curing catalyst as the catalyst for the epoxy resin is as follows. The heat resistance (for example, glass transition temperature) of the cured product obtained by curing the epoxy resin using the cationic curing catalyst is higher than that of the cured product cured using another curing agent (for example, acid anhydride). Because. Thus, the reason why the heat resistance of the cured product using the cationic curing catalyst is higher than that using the other catalyst is that the cured product obtained by curing the epoxy resin using the cationic curing catalyst is crosslinked. The density is expected to be higher than the crosslink density of a cured product cured with another curing agent (for example, an acid anhydride).

Furthermore, when the epoxy resin and the cationic curing catalyst are used, the resulting resin material can be cured at a low temperature in a short time. Thus, when it can be hardened at low temperature, it can reduce that light leak arises. The reason is considered as follows.
The light leakage occurs when the resin near the interface is stretched due to strain at the interface between the glass fiber base material and the resin, and birefringence occurs in the resin. This distortion is caused by the difference between the amount of thermal expansion at the curing temperature of the resin and the amount of thermal expansion of the resin after curing (room temperature after curing) (the amount of shrinkage of the resin during the curing temperature → room temperature cooling process). That is, when the resin is cured at a high temperature, the resin is fixed (cured) with a large amount of thermal expansion, and a large strain remains in the cured resin. On the other hand, if the resin can be cured at a low temperature, it can be fixed (cured) with a relatively small amount of thermal expansion, so the strain remaining in the cured resin can be reduced, thereby improving light leakage. Can do.
Here, “suppression of light leakage” is required when a transparent substrate is used as a substrate for a display element such as a liquid crystal cell. Light leakage means that, for example, a transparent substrate is provided between polarizing plates in a liquid crystal cell or the like, but light transmission occurs when the display is in a black display state (under crossed crossed Nicols), thereby reducing the display quality of the image display device. A problem occurs.

  As described above, the epoxy resin represented by the formula (1) is included as an essential component, but the content thereof is not particularly limited, and is preferably 50 to 98% by weight, particularly 80 to 95% by weight of the entire resin material. preferable. When the content is within the above range, the transparency is particularly excellent.

  In addition to the epoxy resin represented by the formula (1), a normal novolac type epoxy resin, a bisphenol type epoxy resin, or the like may be used in combination as the epoxy resin.

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

  Examples of the thermal cationic curing catalyst include aromatic sulfonium salts, aromatic iodonium salts, ammonium salts, aluminum chelates, and boron trifluoride amine complexes. Specifically, as an aromatic sulfonium salt, SI-60L, SI-80L, SI-100L manufactured by Sanshin Chemical Co., Ltd., and hexafluoroantimonate salts such as SP-66 and SP-77 manufactured by Asahi Denka Co., Ltd. are listed. Examples of the aluminum chelate include ethyl acetoacetate aluminum diisopropylate, aluminum tris (ethyl acetoacetate) and the like, and examples of the boron trifluoride amine complex include boron trifluoride monoethylamine complex, boron trifluoride imidazole complex, And boron trifluoride piperidine complex.

  The content of the cationic catalyst is not particularly limited, but is preferably 0.1 to 3 parts by weight, particularly 0.5 to 1.5 parts by weight with respect to 100 parts by weight of the epoxy resin represented by the formula (1). Is preferred. If the content is less than the lower limit, the curability may be lowered, and if the content exceeds the upper limit, the transparent core substrate may become brittle.

The resin material is not particularly limited, and may further include a second component capable of adjusting the refractive index of the epoxy resin represented by the formula (1). Thereby, adjustment of the refractive index of the epoxy resin shown by the said Formula (1) and the material which comprises a sheet-like base material can be made easy.
Examples of the second component include those that are compatible with the epoxy resin represented by the formula (1), or fillers that have an average dispersed particle diameter of 100 nm or less even if they are not compatible.
Examples of those that are compatible with the epoxy resin represented by the formula (1) include thermoplastic resins such as polymethyl methacrylate, polycarbonate, thermoplastic polyimide, and polyetherimide, and thermoplastics such as urethane type elastomer and polyether type elastomer. Known epoxy resins such as elastomers, bisphenol A type epoxy resins and bisphenol F type epoxy resins and hydrogenated epoxy resins thereof, bisphenol S type epoxy resins, epoxy resins having a fluorene skeleton and alicyclic epoxy resins, di [1- Ethyl (3-oxetanyl)] methyl ether, 1,3-bis (1-ethyl-3-oxetanyl) methoxybenzene, oxetanylsilsesquioxane, oxetanyl silicate and the like containing a silicate structure in the molecular structure, bi It can be mentioned ether resin. Among these, those containing a silicate structure in the molecular structure are preferable. Thereby, especially transparency can be improved.

In addition, the second component (particularly, compatible with the epoxy resin represented by the formula (1)) is not particularly limited, but a functional group capable of reacting with the epoxy group of the epoxy resin represented by the formula (1). It preferably has a group. Thereby, the refractive index can be adjusted without reducing the heat resistance.
Examples of the functional group include an oxetanyl group, an epoxy group, and a vinyl group. Among these, an oxetanyl group is preferable. Thereby, a transparent core substrate with a high crosslink density can be obtained, and heat resistance can be improved.
Specific examples of the second component include silsesquioxane having an oxetanyl group, silicate having an oxetanyl group, and the like. Thereby, the transparent substrate which maintains transparency and is excellent in heat resistance can be obtained.

  The refractive index of the second component is not particularly limited, but the sheet-like base material 21 is a glass fiber, and the refractive index of the epoxy resin represented by the formula (1) is higher than the refractive index of the glass fiber. In this case, it is preferable that the refractive index of the second component is lower than that of the epoxy resin. Thereby, the transparency of a transparent substrate can be improved.

Examples of the filler having an average dispersed particle diameter of 100 nm or less include silica fine particles, titanium oxide fine particles, zirconia oxide fine particles, and alumina fine particles.
Among these, silica fine particles are preferable. Thereby, high transparency can be obtained without deteriorating the physical properties of the cured product such as heat resistance and linear expansion coefficient.
Furthermore, although the refractive index of the said filler is not specifically limited, It is preferable that it is lower than the epoxy resin shown by the said Formula (1). Thereby, the refractive index can be adjusted more easily.
The average dispersed particle size can be evaluated using, for example, an electron microscope.

  Although content of the said 2nd component is not specifically limited, 1 to 40 weight% of the whole said resin material is preferable, and 5 to 20 weight% is especially preferable. When the content is within the above range, the transparency can be improved without impairing the properties of the epoxy resin represented by the formula (1).

  In addition to the epoxy resin and the cationic curing catalyst as described above, the resin material may be used in combination with a thermoplastic oligomer, a thermosetting oligomer, or the like. When these oligomers are used in combination, the composition ratio is preferably adjusted so that the overall refractive index matches the refractive index of the material constituting the sheet-like substrate. In addition, the resin layer of the present invention includes a small amount of antioxidant, ultraviolet absorber, dye / pigment, and other inorganic fillers as required, as long as the properties such as transparency, solvent resistance, and heat resistance are not impaired. Or the like.

  The refractive index of a cured product obtained by curing such a resin material is not particularly limited, but is preferably 1.4 to 1.6, and particularly preferably 1.5 to 1.55. When the refractive index is within the above range, it becomes easy to adjust the refractive index of the sheet-like substrate and the refractive index of the resin material.

  The difference between the refractive index of the cured product obtained by curing the resin material and the refractive index of the glass fiber is not particularly limited, but is preferably 0.01 or less, particularly 0.005 or less. Is preferred. When the refractive index difference is within the above range, the transparency of the obtained transparent substrate is particularly excellent.

  In the first impregnation and the second impregnation in the supporting step, the same resin material or different resin materials may be supported, but it is preferable to support the same resin material. Thereby, the adhesive strength at the interface can be improved.

  After supporting such a resin material on the sheet-like base material 21, excess resin material is removed by the squeeze bar 321, and then the support member 41 is supplied from the support member supply unit 42 and laminated by the lami roll 43 (lamination Process). Thereby, the protrusion which protrudes from the surface of the sheet-like base material 21 can be pressed to the inner surface side of the sheet-like base material 21. Thereby, the smoothness of the surface of the transparent core substrate 1 can be particularly improved.

Although it does not specifically limit in the said lamination process, It is preferable to implement in the state in which the said resin material is uncured (especially, before reaching solidification). Thereby, the smoothness of the transparent core substrate 1 can be particularly improved.
Here, before the resin material is solidified, for example, it can be expressed in a state where the storage elastic modulus of the resin material is 1 × 10 ⁴ Pa or more. Such a storage elastic modulus is obtained by, for example, using ARES (Ales) manufactured by Rheometric Co., Ltd. as a measuring device, and sandwiching a liquid resin material as a measuring condition in a 25 mm parallel plate, with a frequency of 1 rad / sec and a strain of 0. It can be evaluated by measuring from room temperature to a predetermined temperature at a temperature rising rate of 3 ° C./min.

Examples of the support member 41 include a metal belt, a metal foil, a glass plate, and a resin sheet.
Specific examples of the metal belt include endless stainless steel belts, examples of the metal foil include stainless steel foil, copper foil, and aluminum foil. Specific examples of the resin sheet include polyimide films and polyester films. And engineering plastic film. Among these, copper foil or polyimide is preferable. Thereby, light leakage of the finally obtained transparent substrate can be reduced.

  The average linear expansion coefficient of the support member 41 at room temperature to 150 ° C. is not particularly limited, but is preferably 1 to 80 ppm, particularly preferably 10 to 25 ppm. When the average linear expansion coefficient is within the above range, in addition to excellent smoothness, the effect of suppressing light leakage is improved.

The average linear expansion coefficient of the support member 41 from room temperature to 150 ° C. is A [ppm], and the average linear expansion coefficient of the cured product obtained by impregnating the epoxy resin into the sheet-like base material 21 from room temperature to 150 ° C. is B [ [ppm], the difference (A−B) is not particularly limited, but is preferably 0 to 15 [ppm], and particularly preferably 3 to 10 [ppm]. If the difference is less than the lower limit, the effect of suppressing light leakage and the effect of improving the surface smoothness may be reduced, and if the difference exceeds the upper limit, the occurrence of undulation in the transparent core substrate may be suppressed. The effect may be reduced.
Here, the average linear expansion coefficient of the sheet-like base material 21 is an average of the sheet-like base material 21 after the sheet-like base material 21 is impregnated with a resin material and then heat-treated at 250 ° C. for 120 minutes (after curing). The linear expansion coefficient was measured.
The average coefficient of linear expansion is measured, for example, using a thermomechanical analyzer (TMA / SS6000) manufactured by Seiko Electronics, using a quartz chuck for holding the sample, a static load of 49 N, and a heating rate of 5 ° C./min. (See JP 2003-166959 A).

Thus, it can be considered as follows that the difference in the average linear expansion coefficient (A−B) can be suppressed from causing undulation in the transparent core substrate.
When the resin material carried on the sheet-like base material 21 is cured in a state where the support member 41 is laminated on the sheet-like base material 21, an expansion amount is increased between the sheet-like base material 21 and the support member 41. Differences occur. In this case, if the average linear expansion coefficient of the support member 41 is smaller than that of the sheet-like base material 21, wrinkles may occur in the sheet-like base material 21. On the other hand, if the average linear expansion coefficient of the support member 41 is too larger than that of the sheet-like base material 21, the sheet-like base material 21 is excessively stretched in the curing process, causing distortion inside, thereby causing undulation. There is a case.
On the other hand, if the average linear expansion coefficient of the support member 41 is slightly larger than that of the sheet-like base material 21, the sheet-like base material 21 can be kept in a slightly stretched state in the curing step, and wrinkles are caused. No swell or swell occurs.

  Examples of the laminating conditions include a case where the line speed is 0.1 to 10 m / min, the linear pressure is 0.1 to 20 kg / cm, and the pressure is normal pressure and room temperature. Examples of the laminate roll include a metal roll and a rubber roll, and a rubber roll having a hardness of 80 or more is particularly preferable.

In the curing step 5, the uncured resin material carried on the sheet-like substrate 21 is cured. Thereby, the heat resistance of the transparent core substrate 1 can be improved.
The conditions for curing the resin material are not particularly limited, but it is preferable to cure at a low curing temperature and a short curing time. Thereby, the light leakage of the transparent substrate 8 finally obtained can be reduced. The reason why this light leakage can be reduced is considered as follows. The light leakage occurs when the resin near the interface is stretched due to strain at the interface between the glass fiber base material and the resin, and birefringence occurs in the resin. This distortion is caused by the difference between the amount of thermal expansion at the curing temperature of the resin and the amount of thermal expansion of the resin after curing (room temperature after curing) (the amount of shrinkage of the resin during the curing temperature → room temperature cooling process). That is, when the resin is cured at a high temperature, the resin is fixed (cured) with a large amount of thermal expansion, and a large strain remains in the cured resin. On the other hand, if the resin can be cured at a low temperature, it can be fixed (cured) with a relatively small amount of thermal expansion, so the strain remaining in the cured resin can be reduced, thereby improving light leakage. Can do.
Although the said curing temperature is not specifically limited, 60-150 degreeC is preferable and 80-100 degreeC is especially preferable. When the curing temperature is within the above range, the amount of strain remaining on the transparent core substrate particularly after the curing treatment can be reduced.

  The curing time is not particularly limited, but is preferably 1 to 20 minutes, and particularly preferably 3 to 6 minutes. When the curing time is within the above range, the productivity is particularly excellent and the transparent core substrate can be stably produced.

  Although the temperature increase rate of the sheet-like base material 21 in such a hardening process 5 is not specifically limited, 1-50 degreeC / min is preferable and 5-20 degreeC / min is especially preferable. When the temperature increase rate is within the above range, the transparent core substrate can be produced particularly stably.

  Examples of a method for performing the curing step 5 include a method of passing the sheet-like base material 21 through a dryer 51 as illustrated, a method of passing the sheet-like base material 21 through an infrared heater, and the like. Among these, the method of allowing the sheet-like base material 21 to pass through the infrared heater is preferable. Thereby, control of the temperature increase rate of the sheet-like base material 21 can be made easy.

In the peeling step, the support member 41 laminated on the sheet-like substrate 21 is peeled off. As a result, the transparent core substrate 1 having excellent surface smoothness can be obtained.
Examples of the peeling method include a method of peeling the support member 41 while winding it with a winder, and a method of etching with an acid or the like when the support member 41 is a metal foil.

After peeling off the sheet-like base material 21 in the peeling step, the transparent core substrate 1 is obtained by winding it with a winder. The average surface roughness of the transparent core substrate 1 thus obtained is preferably 100 μm or less, particularly preferably 50 μm or less, and most preferably 10 μm or less.
The average surface roughness can be evaluated by, for example, an interference type surface roughness meter (New View 5032 from Zygo).

As mentioned above, although the manufacturing method of the transparent substrate was demonstrated based on suitable embodiment shown in FIG. 1, the manufacturing method of this invention is not limited to this. Specifically, as shown in FIG. 2, after the core base material 11 is prepared in advance by the supporting process 3 and the curing process 5, the core base material supplied from the core base material supply unit 2 ′ as shown in FIG. The transparent core substrate 1 may be obtained through a method in which a resin material is further supported on the surface 11 and cured through the laminating step 4.
The transparent core substrate 1 thus obtained may be used as the transparent substrate 8 as it is, but it is preferable to further improve the surface smoothness by the smoothing step 6 described later.

When further smoothness of the surface is required for the obtained transparent core substrate 1, a smoothing step of providing a resin layer 63 on at least one surface of the transparent core substrate 1 is performed, as shown in FIG. A transparent substrate 8 may be obtained.
In the smoothing step 6, as shown in FIG. 5, the transparent core substrate 1 supplied from the unwinding unit 61 is cleaned by the cleaning unit 62, and the resin varnish 63 ′ (later forming the resin layer 63) is removed. In addition, the transfer member 641 is supplied from the supply unit 64 and laminated to obtain a laminate 65. In order to irradiate the obtained laminate 65 with ultraviolet light 66, the ultraviolet light irradiation part 661 is passed. Next, the transfer member 641 is peeled off by the peeling portion 67 and further heated by the heating portion 68 to finally obtain the transparent substrate 8 as shown in FIG.

Thus, although the smoothness (average surface roughness) of the surface of the obtained transparent substrate 8 is not specifically limited, 2 micrometers or less are preferable and especially 0.5 micrometers or less are preferable. Thereby, the transparent substrate 8 can be used suitably as a resin substrate for display elements.
The average surface roughness can be evaluated by, for example, an interference type surface roughness meter (New View 5032 from Zygo).

The resin varnish 63 ′ may be of the same type as the resin material carried on the sheet-like base material 21 or may be of a different type. For example, active energy rays (or active energy rays and heat as necessary) may be used. And reactive monomers or oligomers such as acrylates, epoxies, oxetanes, and vinyl ethers that can be crosslinked in combination.
More specifically, the acrylate preferably contains a bifunctional or higher acrylate. Thereby, in addition to being excellent in transparency, heat resistance and solvent resistance can be particularly improved. Examples of the bifunctional or higher acrylate include epoxy acrylate, urethane acrylate, polyester acrylate, acrylate having an isocyanurate structure, acrylate having a cyclic structure, and acrylate having an alicyclic structure.

  The epoxy is also preferably a bifunctional or higher epoxy. Thereby, in addition to being excellent in transparency, heat resistance and solvent resistance can be particularly improved. Examples of the bifunctional or higher epoxy include bisphenol A type epoxy resin, hydrogenated bisphenol A type epoxy resin, and alicyclic epoxy resin.

  Oxetane is also preferably bifunctional or higher oxetane. Examples of the bifunctional or higher oxetane include di [1-ethyl (3-oxetanyl)] methyl ether, 1,3-bis [(1-ethyl-3-oxetanyl)] methoxybenzene, oxetanylsilsesquioxane, and oxetanyl. Examples include silicates.

The catalyst used for the resin varnish 63 ′ is preferably activated by irradiation with ultraviolet rays or the like. For example, when acrylate is included, benzophenone, benzoin methyl ether, benzoin propyl ether, diethoxyacetophenone, 1-hydroxy-cyclohexyl phenyl ketone, 2,6-dimethylbenzoylphenylphosphine oxide, etc. that generate radicals by active energy rays are listed. It is done.
Moreover, when an epoxy resin and an oxetane resin are used, an aromatic sulfonium salt, an aromatic iodonium salt, or the like that generates a cationic species with active energy rays is preferable.

The resin varnish 63 ′ finally forms the resin layer 63 on the surface of the transparent substrate 8 by laminating the transfer member 641.
Although the thickness of the resin layer 63 is not specifically limited, 1-15 micrometers is preferable and especially 3-7 micrometers is preferable. When the thickness is within the above range, distortion is particularly difficult to occur in the transparent core substrate 1, and undulation is difficult to occur.

  The transfer member 641 is not particularly limited as long as it can transmit the ultraviolet light 66. For example, a resin sheet such as polyethylene terephthalate, a film manufactured by a casting method, a film subjected to surface polishing, or the like is used. It is possible to perform mold release treatment on these smooth surfaces. Examples of the resin as a raw material for the resin sheet include polyester, polysulfone, polyethersulfone, polyetherketone, polyetheretherketone, polyimide, polyamideimide, polycarbonate, epoxy resin, acrylic resin, norbornene-based resin, and blends thereof. Examples thereof include resins.

  Next, in the ultraviolet irradiation unit 661, the resin layer 63 is cured by irradiating the laminate 65 of the transparent core substrate 1, the resin layer 63, and the transfer member 641 with the ultraviolet ray 66.

  Then, the transfer member 641 is peeled from the laminate 65 by the peeling portion 67 and further heated by the heating portion 68 to obtain the final transparent substrate 8.

  The average linear expansion coefficient at 30 to 150 ° C. of the transparent substrate 8 thus obtained is not particularly limited, but is preferably 40 ppm or less, particularly preferably 1 to 20 ppm. When the average linear expansion coefficient is within the above range, it is possible to reduce the occurrence of warpage particularly in the manufacturing process.

  Further, the light transmittance at a wavelength of 550 nm of the transparent substrate 8 is not particularly limited, but is preferably 80% or more, and particularly preferably 85 to 95%. When the light transmittance is within the above range, the display performance is excellent, and therefore, it can be particularly suitably used for a resin substrate for display elements.

  Although the glass transition temperature of the transparent substrate 8 is not specifically limited, 230 degreeC or more is preferable and especially 250 degreeC or more is preferable. If the glass transition temperature is lower than the lower limit, the substrate may be deformed due to insufficient strength and elastic modulus of the substrate depending on conditions at a high temperature.

  The thickness of the transparent substrate 8 is not particularly limited, but is preferably 50 to 2,000 μm, particularly preferably 100 to 1,000 μm. When the thickness is within the above range, the surface smoothness is particularly excellent, and the weight can be reduced as compared with the glass substrate. Furthermore, when the thickness is within the above range, it is particularly preferably used for a plastic substrate for liquid crystal display elements, a substrate for color filters, a plastic substrate for organic EL display elements, a touch panel substrate, an electronic paper substrate, a solar cell substrate, and the like. be able to.

Next, the electronic device of the present invention will be described using a liquid crystal display element substrate as a specific example. As shown in FIG. 6, the liquid crystal display element substrate 9 is provided with polarizing plates 92a and 92b on both surfaces of a liquid crystal cell 91 via transparent substrates 8a and 8b. The transparent substrate 8 shown in FIG. 4 is used for at least one (preferably both) of 8a and 8b.
A filter 93 is provided between the liquid crystal cell 91 and the transparent substrate 8a (upper side in FIG. 6). On the other hand, on the lower side of the liquid crystal cell 91 (lower side in FIG. 6), the TFT 94 is provided between the transparent substrate 8b. These transparent substrates 8a and 8b are lighter in weight and superior in strength than conventionally used glass substrates.
An image is formed by the light source 95 irradiated from the lower side of the liquid crystal display element substrate 9.
Thus, although the case where the transparent substrate 8 of this invention was used for the display element substrate for liquid crystals was demonstrated, this invention is not limited to this, The board | substrate for liquid crystal display elements containing an active matrix type, For organic electroluminescent display elements It can be suitably used for an electronic device such as a substrate for a display element such as a substrate, a substrate for a color filter, a substrate for a touch panel, an electronic paper substrate, a solar cell substrate, or a transparent plate.

EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example and a comparative example, this invention is not limited to this.
Example 1
1. Resin material 100 parts by weight of 2,2-bis (3 ′, 4′-epoxycyclohexyl) propane (manufactured by Daicel Chemical Industries, Ltd., E-DOA) as the epoxy resin, and aromatic sulfonium thermal cation catalyst as the cationic curing catalyst A resin material was prepared by mixing 1 part by weight (manufactured by Sanshin Chemical Co., Ltd., SI-100L). The average linear expansion coefficient of the cured product obtained by curing this resin material was 66 ppm.

2. Transparent core substrate manufacturing / supporting step and laminating step As a sheet-like base material, a glass fiber base material (100 μm thick S glass-based glass cloth: refractive index 1.528, manufactured by Unitika Co., Ltd., # 2117 type) is baked out. After removing the organic matter, the one treated with glycidoxypropyltrimethoxysilane (epoxysilane) was used.
As shown in FIG. 1, the resin material was supported on the sheet-like base material by first and second impregnation. Then, before the resin material solidified, copper foil (thickness 12 μm, average linear expansion coefficient 17 ppm, surface roughness 1.5 μm) was laminated from both sides of the sheet-like substrate as a supporting member.

Curing step Next, the sheet-like substrate was passed at 0.15 m / min through an IR heater set in 6 zones of 40 ° C-53 ° C-67 ° C-80 ° C-100 ° C-120 ° C, and resin The material was cured (temperature increase rate was calculated to be 10 ° C./min).
And the support member was peeled with the winder, and the transparent core substrate was obtained.
The average surface roughness of the surface of the obtained transparent core substrate was 1.5 μm.

3. Smoothing Step In order to further smooth the above-described transparent core substrate, 100 parts by weight of acrylic resin (M-315 manufactured by Toagosei Co., Ltd.) and acrylic resin (Nippon Kayaku Co., Ltd.) are formed from both sides of the transparent core substrate as shown in FIG. After applying a resin varnish containing 100 parts by weight of R-604) and 3 parts by weight of Irgacure 184 (manufactured by Ciba Specialty Chemicals) as an ultraviolet curing agent, a PET film (manufactured by Toyobo Co., Ltd., thickness) 125 [mu] m) was laminated, and the cured resin layer was formed by irradiating with 500 mJ / cm < ² > of ultraviolet rays at the ultraviolet irradiation section.
Subsequently, the transfer member was peeled off to obtain a transparent substrate in which a resin layer was formed on both surfaces of the transparent core substrate and the surface was smoothed. The average surface roughness of this transparent substrate was 0.15 μm. Moreover, the light transmittance in wavelength 550nm of this transparent substrate was 91%, and the average linear expansion coefficient of 30-150 degreeC was 13 ppm.

(Example 2)
In the production of the transparent core substrate, the same procedure as in Example 1 was performed except that the following members were used as support members.
A polyimide film (manufactured by Ube Industries, Upilex 50S, thickness 50 μm, average linear expansion coefficient 16 ppm) was used as the support member. The average surface roughness of the obtained transparent core substrate was 0.9 μm.
Moreover, the average surface roughness of the transparent substrate finally obtained was 0.13 μm. Moreover, the light transmittance in wavelength 550nm of this transparent substrate was 90%, and the average linear expansion coefficient of 30-150 degreeC was 13 ppm.

(Example 3)
The same resin material as that of Example 1 was used except that the following materials were used.
100 parts by weight of 2,2-bis (3 ′, 4′-epoxycyclohexyl) propane (manufactured by Daicel Chemical Industries, Ltd., E-DOA) as the epoxy resin, and an aromatic sulfonium thermal cation catalyst (three 1 part by weight of Shin Chemical Co., Ltd., SI-100L) and 10 parts by weight of oxetanylsilsesquioxane (manufactured by Toagosei Co., Ltd., product number OX-SQ-H) were used as the second component. In addition, the average linear expansion coefficient of the hardened | cured material obtained by hardening | curing this resin material was 71 ppm.
The average surface roughness of the surface of the obtained transparent core substrate was 1.5 μm. Further, the average surface roughness of the finally obtained transparent substrate was 0.15 μm. Moreover, the light transmittance in wavelength 550nm of this transparent substrate was 90%, and the average linear expansion coefficient of 30-150 degreeC was 13 ppm.

Example 4
The same resin material as that of Example 1 was used except that the following materials were used.
100 parts by weight of 2,2-bis (3 ′, 4′-epoxycyclohexyl) propane (manufactured by Daicel Chemical Industries, Ltd., E-DOA) as the epoxy resin, and an aromatic sulfonium thermal cation catalyst (three 1 part by weight of Shin Chemical Co., Ltd. (SI-100L) and 12 parts by weight of oxetanyl silicate (product number OX-SC, manufactured by Toagosei Co., Ltd.) were used as the second component. In addition, the average linear expansion coefficient of the hardened | cured material obtained by hardening | curing this resin material was 70 ppm.
The average surface roughness of the surface of the obtained transparent core substrate was 1.5 μm. Further, the average surface roughness of the finally obtained transparent substrate was 0.15 μm. Moreover, the light transmittance of this transparent substrate at a wavelength of 550 nm was 90%, and the average linear expansion coefficient at 30 to 150 ° C. was 14 ppm.

(Example 5)
The same procedure as in Example 1 was performed except that an aliphatic sulfonium catalyst (Asahi Denka Kogyo Co., Ltd., CP77) was used as the cationic curing catalyst.
The average surface roughness of the surface of the obtained transparent core substrate was 1.5 μm. Further, the average surface roughness of the finally obtained transparent substrate was 0.15 μm. Moreover, the light transmittance in wavelength 550nm of this transparent substrate was 85%, and the average linear expansion coefficient of 30-150 degreeC was 16 ppm.

(Comparative Example 1)
The procedure was the same as Example 1 except that hydrogenated bisphenol A (manufactured by Japan Epoxy Resin Co., Ltd., YX-8000) was used as the epoxy resin.
The average surface roughness of the surface of the obtained transparent core substrate was 1.5 μm. Further, the average surface roughness of the finally obtained transparent substrate was 0.15 μm. Moreover, the light transmittance in wavelength 550nm of this transparent substrate was 82%, and the average linear expansion coefficient of 30-150 degreeC was 16 ppm.

(Comparative Example 2)
The same procedure as in Example 1 was performed except that an imidazole-based curing catalyst 2MZ (manufactured by Shikoku Kasei Co., Ltd.) was used instead of the cationic curing catalyst.
In addition, in the mixing | blending of the comparative example 2, hardened | cured material could not be obtained and evaluation mentioned later could not be performed.

The following evaluation was performed about the transparent substrate obtained by each Example and each comparative example. The evaluation items are shown together with the contents. The obtained results are shown in Table 1.
1. Average Surface Roughness The average surface roughness of the obtained transparent core substrate and transparent substrate was evaluated with an interference type surface roughness meter (Zygo New View 5032, 2.5 × lens).

2. Transparency The transmittance at 550 nm of the obtained transparent substrate was measured with a spectrophotometer U3200 (manufactured by Shimadzu Corporation).

3. Heat Resistance The heat resistance of the obtained transparent substrate was evaluated by tan δ (peak top value) measured with a viscoelasticity measuring device DMS-210 (manufactured by Seiko Instruments Inc.).

4). Light leakage The obtained transparent substrate was evaluated for light leakage. The evaluation method was carried out in a crossed Nicol state using a polarizing microscope, and then evaluated at a position where light leakage was strongest while rotating the transparent substrate on the stage. Each code is as follows.
A: Light leakage could not be detected.
○: Although light leakage could be detected, the level was practically satisfactory.
(Triangle | delta): There was light leakage and it was the level which cannot be used practically.
X: There is a large amount of light leakage.

4). Swelling The presence or absence of swell of the obtained transparent substrate was evaluated by a fluorescent lamp reflection method. Each code is as follows.
(Double-circle): It was able to be recognized without the fluorescent lamp reflection image being distorted.
○: Fluorescent lamp reflection image appeared distorted, but practically no problem.
Δ: Level at which a fluorescent lamp reflection image looks distorted and has a problem in practical use.
X: The fluorescent lamp reflection image was distorted and could not be recognized.

As is clear from Table 1, Examples 1 to 5 had a small average surface roughness and a high light transmittance. As a result, it was shown that a transparent substrate having a smooth surface was obtained.
In addition, Examples 1, 2 and 4 were particularly high in tan δ and excellent in heat resistance.
In addition, Examples 1 and 2 showed low light leakage, and were particularly excellent as substrates for liquid crystal display elements.
In Examples 1 and 2, it was confirmed that there was no distortion of the fluorescent lamp reflection image and the undulation of the transparent substrate was small.
Moreover, the electronic device using the transparent substrate obtained in Examples 1-5 operated normally.

It is the schematic which shows an example of the manufacturing method of a transparent core board | substrate. It is the schematic which shows an example of the manufacturing method of a transparent core board | substrate. It is the schematic which shows an example of the manufacturing method of a transparent core board | substrate. It is sectional drawing which shows an example of a transparent substrate. It is the schematic which shows an example of a smoothing process. It is sectional drawing which shows an example of the display element substrate for liquid crystals.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Transparent core board | substrate 11 Core base material 2 Sheet-like base material supply part 2 'Core base material supply part 21 Sheet-like base material 22 Feed roll 3 Supporting process 31 1st impregnation part 311 1st kiss roll 312 2nd kiss roll 313 Feed roll 32 2nd impregnation part 321 squeeze bar 4 lamination process 41 support member 42 support member supply part 43 lami roll 5 curing process 51 dryer 6 smoothing process 61 unwinding part 62 washing | cleaning part 63 resin layer 63 'resin varnish 64 supply part 641 transfer member 65 Laminated body 66 Ultraviolet ray 661 Ultraviolet ray irradiation part 67 Peeling part 68 Heating part 8 Transparent substrate 8a Transparent substrate 8b Transparent substrate 9 Display element substrate for liquid crystal 91 Liquid crystal cell 92a Polarizing plate 92b Polarizing plate 93 Filter 94 TFT
95 Light source

Claims (19)

A method for producing a transparent substrate used in an electronic device,
A carrying step of carrying an uncured resin material containing an epoxy resin represented by formula (1) and a cationic curing catalyst on a sheet-like substrate and a curing step of curing the resin material are continuously performed. A method for producing a transparent substrate, comprising forming a transparent core substrate.

  The method for producing a transparent substrate according to claim 1, further comprising a laminating step of laminating a support member on at least one surface of the sheet-like base material after the resin material is supported on the sheet-like base material.   The method for producing a transparent substrate according to claim 2, wherein the laminating step is performed in a state where the resin material is uncured after the supporting step and before the curing step.   4. The method for producing a transparent substrate according to claim 2, wherein in the laminating step, a protrusion projecting from the surface of the sheet-like base material is pressed against the sheet-like base material surface side by the support member.   The method for producing a transparent substrate according to claim 2, further comprising a peeling step for peeling the support member after the laminating step.   The method for producing a transparent substrate according to claim 1, wherein the resin material further includes a second component capable of adjusting a refractive index of the epoxy resin.   The method for producing a transparent substrate according to claim 6, wherein a refractive index of the second component is lower than a refractive index of the epoxy resin.   The method for producing a transparent substrate according to claim 6 or 7, wherein the second component has a functional group capable of reacting with an epoxy group of the epoxy resin.   The method for producing a transparent substrate according to claim 8, wherein the functional group is an oxetanyl group, an epoxy group, or a vinyl ether group.   The method for producing a transparent substrate according to claim 6, wherein the second component of the resin material includes a silicate structure in a molecular structure.   The method for producing a transparent substrate according to claim 6, wherein the second component mainly contains silsesquioxane having an oxetanyl group.   The method for producing a transparent substrate according to any one of claims 1 to 11, wherein the sheet-like substrate is composed of an aggregate of glass fibers.   The method for producing a transparent substrate according to claim 12, wherein a difference between a refractive index of the glass fiber and a refractive index after the resin material is cured is 0.01 or less.   The method for producing a transparent substrate according to any one of claims 1 to 13, further comprising a smoothing step of providing a resin layer on at least one surface of the transparent core substrate.   The method for producing a transparent substrate according to any one of claims 1 to 14, wherein an average linear expansion coefficient at 30 to 150 ° C of the transparent substrate is 40 ppm or less.   The method for producing a transparent substrate according to claim 1, wherein the light transmittance at a wavelength of 550 nm is 80% or more.   The method for producing a transparent substrate according to claim 1, wherein the transparent substrate is a resin substrate for a display element.   A transparent substrate obtained by the method for producing a transparent substrate according to claim 1. An electronic device comprising the transparent substrate according to claim 18.

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