JP2012177980A - Resin board for lower electrode substrate and lower electrode board and touch panel using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin board for lower electrode substrate which is lightly weighted and hardly cracked for suppressing the coloring of a display image when the screen of a touch panel is viewed from an oblique direction.SOLUTION: Disclosed is a resin board to be used for the lower electrode substrate of a touch panel, that is, a resin board for lower electrode substrate configured by laminating acryl-based resin layers on the both surfaces of a methyl methacrylate/styrene copolymer resin layer. It is desired that the methyl methacrylate/styrene copolymer resin layer and the acryl-based resin layer laminated on the both surfaces are laminated so as to be integrated by co-extrusion.

Description

  The present invention relates to a resin plate for a lower electrode substrate. The present invention also relates to a lower electrode plate and a touch panel using a resin plate for a lower electrode substrate.

A resistive touch panel has a lower electrode plate with a transparent electrode film formed on one side of the substrate and an upper electrode plate facing each other with a spacer between the electrodes so that the transparent electrode films face each other For example, it is installed in a liquid crystal display and used as an information input device for the liquid crystal display.
When installing a touch panel on a liquid crystal display, usually, a touch panel is first placed on a liquid crystal panel, and then a quarter-wave plate, a polarizing plate, and a display protective plate are placed on the touch panel in this order.

  In Patent Document 1, of the two electrode plates constituting the resistive touch panel, the substrate of the lower electrode plate that is the electrode plate in contact with the liquid crystal panel (that is, the lower electrode substrate) is a glass plate, A touch panel is described in which the substrate of the upper electrode plate (that is, the upper electrode substrate) is a polyethylene terephthalate resin plate. However, the touch panel described in Patent Document 1 has a problem that the glass plate is heavy and easily broken.

JP 2006-277769 A

  An object of the present invention is to provide a resin plate for a lower electrode substrate that is difficult to break and has good optical characteristics (for example, suppression of coloring of an image displayed on a liquid crystal display provided with a touch panel).

  As a result of intensive studies to solve the above problems, the present inventors have completed the present invention.

That is, the present invention relates to the following inventions.
(1) A resin plate for a lower electrode substrate, which is a resin plate used for a lower electrode substrate of a touch panel and has an acrylic resin layer on both sides of a methyl methacrylate-styrene copolymer resin layer.
(2) Re (0) is the retardation value when monochromatic light having a wavelength of 590 nm is incident at an angle of 0 ° with respect to the normal of the resin plate surface, and Re ( 50), the resin plate according to (1), wherein Re (0) and Re (50) satisfy the formula: | Re (0) −Re (50) | /50≦1.6.
(3) The retardation value Re (50) when monochromatic light having a wavelength of 590 nm is incident at an angle of 50 ° with respect to the normal line of the resin plate surface is 90 nm or less, as described in (1) or (2) above Resin plate.
(4) The resin board in any one of said (1)-(3) whose thickness of an acrylic resin layer is 0.1 mm or less.
(5) A film-like product having an acrylic resin layer on both sides of a methyl methacrylate-styrene copolymer resin layer is melt-extruded from a die and sandwiched between a first cooling roll and a second cooling roll, and the second cooling roll The resin plate according to any one of (1) to (4), wherein the resin plate is wound on a third cooling roll and then wound on a third cooling roll.
(6) The resin plate as described in said (5) whose 1st cooling roll is a metal elastic roll provided with the metal thin film in the outer peripheral part, and a 2nd cooling roll is a metal roll.
(7) A lower electrode plate in which a transparent electrode film is provided on one surface of the resin plate according to any one of (1) to (6).
(8) A touch panel configured by disposing a lower electrode plate and an upper electrode plate to face each other with a spacer interposed between the electrode plates so that the transparent electrode films face each other, wherein the lower electrode plate is claimed. A touch panel which is the electrode plate according to 7.
(9) A resin plate having an acrylic resin layer on both sides of a methyl methacrylate-styrene copolymer resin layer,
Re (0) is the retardation value when monochromatic light with a wavelength of 590 nm is incident at an angle of 0 ° with respect to the normal of the resin plate surface, and Re (50) is the retardation value when incident at an angle of 50 °. In this case, Re (0) and Re (50) satisfy the formula: | Re (0) −Re (50) | /50≦1.6.

  The resin plate for a lower electrode substrate according to the present invention is difficult to break, can suppress coloring of an image displayed on the liquid crystal display when the liquid crystal display provided with the touch panel is viewed from an oblique direction, and is excellent in optical characteristics.

It is a schematic explanatory drawing which shows the manufacturing method of the resin plate for lower electrode substrates concerning one Embodiment of this invention.

  The resin plate for a lower electrode substrate of the present invention (hereinafter sometimes referred to as “resin plate”) has an acrylic resin layer on both sides of a methyl methacrylate-styrene copolymer resin layer.

  As the acrylic resin constituting the acrylic resin layer, a methacrylic resin having excellent transparency and high rigidity is suitable. The methacrylic resin is mainly composed of methyl methacrylate units, specifically, methyl methacrylate containing usually 50% by weight or more, preferably 70% by weight or more of methyl methacrylate units based on all monomers. It is preferably a resin, which may be a methyl methacrylate homopolymer having 100% by weight of methyl methacrylate units, or a copolymer of methyl methacrylate and another monomer that can be copolymerized with the methyl methacrylate. It may be a polymer.

  Examples of the other monomer copolymerizable with methyl methacrylate include ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2-ethylhexyl methacrylate, 2-hydroxyethyl methacrylate. Methacrylic acid esters other than methyl methacrylate such as methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, etc. Acrylic acid esters and the like. Examples of styrene and substituted styrenes include halogenated styrenes such as chlorostyrene and bromostyrene, and alkyl styrenes such as vinyltoluene and α-methylstyrene. Furthermore, unsaturated acids such as methacrylic acid and acrylic acid, acrylonitrile, methacrylonitrile, maleic anhydride, phenylmaleimide, cyclohexylmaleimide and the like can also be mentioned. These other monomers that can be copolymerized with methyl methacrylate may be used alone or in combination of two or more.

  The acrylic resin may contain rubber particles. Thereby, the impact resistance of the resin plate can be improved. As the rubber particles, for example, an acrylic multilayer structure polymer, 5 to 80 parts by weight of a rubbery polymer, and 20 to 95 parts by weight of an ethylenically unsaturated monomer such as an acrylic unsaturated monomer is graft-polymerized. And the like, and the like.

  The acrylic multilayer structure polymer should have an elastomer layer of about 20 to 60% by weight, preferably have a hard layer as the outermost layer, and further have a hard layer as the innermost layer. It may be a thing.

  The elastomer layer may be an acrylic polymer layer having a glass transition point (Tg) of less than 25 ° C., specifically, a lower alkyl acrylate, a lower alkyl methacrylate, a lower alkoxyalkyl acrylate, a cyanoethyl acrylate, A polymer obtained by crosslinking one or more monofunctional monomers selected from the group consisting of acrylamide, hydroxy lower alkyl acrylate, hydroxy lower alkyl methacrylate, acrylic acid and methacrylic acid with a polyfunctional monomer such as allyl methacrylate. It is good that it is a layer.

  Examples of the lower alkyl group in the lower alkyl acrylate include linear or branched alkyl groups having 1 to 6 carbon atoms such as methyl, ethyl, propyl, isopropyl, butyl, t-butyl, pentyl and hexyl groups, Examples of the lower alkoxy group in the lower alkoxyalkyl acrylate include linear or branched alkoxy groups having 1 to 6 carbon atoms such as methoxy, ethoxy, propoxy, isopropoxy, butoxy, t-butoxy, pentyloxy, and hexyloxy groups. Can be mentioned. In the case where the monofunctional monomer is used as a main component to form a copolymer, other monofunctional monomers such as styrene and substituted styrene may be copolymerized as a copolymerization component.

  The hard layer may be an acrylic polymer layer having a Tg of 25 ° C. or more, and specifically, an alkyl methacrylate having an alkyl group having 1 to 4 carbon atoms is polymerized alone or as a main component. It is good to be. Examples of the alkyl group having 1 to 4 carbon atoms include linear or branched alkyl groups such as methyl, ethyl, propyl, isopropyl, butyl, and t-butyl.

  When the main component is an alkyl methacrylate having an alkyl group having 1 to 4 carbon atoms, the copolymer component includes other alkyl methacrylates, alkyl acrylates, styrene, substituted styrenes, acrylonitrile, methacrylonitrile, etc. A monofunctional monomer may be used, or a polyfunctional monomer such as allyl methacrylate may be added to form a crosslinked polymer. Examples of the alkyl group in the alkyl methacrylate include the same linear or branched alkyl groups having 1 to 6 carbon atoms as exemplified for the lower alkyl group described above.

  The above-mentioned acrylic multilayer structure polymer is described in, for example, JP-B-55-27576, JP-A-6-80739, JP-A-49-23292, and the like.

  In the graft copolymer obtained by graft polymerization of 20 to 95 parts by weight of an ethylenically unsaturated monomer to 5 to 80 parts by weight of a rubbery polymer, examples of the rubbery polymer include polybutadiene rubber and acrylonitrile / butadiene. Examples include copolymer rubbers, diene rubbers such as styrene / butadiene copolymer rubbers, acrylic rubbers such as polybutyl acrylate, polypropyl acrylate, and poly-2-ethylhexyl acrylate, and ethylene / propylene / non-conjugated diene rubbers. It is done. Examples of the ethylenic monomer used for graft copolymerization with the rubbery polymer include styrene, acrylonitrile, alkyl (meth) acrylate, and the like. These graft copolymers are described, for example, in JP-A Nos. 55-147514 and 47-9740.

  The usage-amount of a rubber particle is 3-150 weight part normally with respect to 100 weight part of acrylic resins, Preferably it is 4-50 weight part, More preferably, it is 5-30 weight part. The greater the amount of rubber particles used, the better the impact resistance of the resin plate, and it tends to be harder to break even when pressed, but if too much rubber particles are used, the surface hardness of the resin plate will decrease. It is not preferable.

  In addition, each composition of the acrylic resin layers on both sides may be the same or different from each other. Moreover, you may add 1 type (s) or 2 or more types, for example, additives, such as a light stabilizer, a ultraviolet absorber, antioxidant, a flame retardant, and an antistatic agent, to an acrylic resin layer as needed.

  On the other hand, as the methyl methacrylate-styrene copolymer resin constituting the methyl methacrylate-styrene copolymer resin layer, usually 1 to 30% by weight of methyl methacrylate units and 1% by weight of styrene units on the basis of all monomer units. Those having 70 to 99% by weight are used, and those having 2 to 15% by weight of methyl methacrylate units and 85 to 98% by weight of styrene units are preferably used. If the proportion of methyl methacrylate units is too small, the rigidity may decrease and the resin plate may be easily broken. On the other hand, if the proportion of methyl methacrylate units is too large, the water absorption rate may increase and the resin plate may be easily warped. is there. In addition, the methyl methacrylate-styrene copolymer resin may have a monomer unit other than the methyl methacrylate unit and the styrene unit, if necessary. Examples of the monomer unit include a divinylbenzene unit. And alkyl acrylate units, and the amount thereof is usually 10% by weight or less based on the total monomer units.

  In addition, one or more additives such as a light stabilizer, an ultraviolet absorber, an antioxidant, a flame retardant, and an antistatic agent are added to the methyl methacrylate-styrene copolymer resin layer as necessary. May be.

  Since the resin plate of the present invention has an acrylic resin layer on both sides of a methyl methacrylate-styrene copolymer resin layer, a touch panel that is lightweight and difficult to break and that uses the resin plate as a lower electrode substrate is installed. Even when the liquid crystal display is viewed from an oblique direction, the display image of the liquid crystal display does not appear to be colored, and the optical characteristics are good. When installing a touch panel on a liquid crystal display, usually, a touch panel is first placed on a liquid crystal panel, and then a quarter-wave plate, a polarizing plate, and a display protective plate are placed on the touch panel in this order. The touch panel exists between two polarizing plates, that is, a polarizing plate 1 constituting a liquid crystal panel and a polarizing plate 2 placed on a quarter-wave plate. The coloring of the display image occurs when the linearly polarized light emitted from the liquid crystal panel through the polarizing plate 1 changes in phase difference between the polarizing plate 1 and the polarizing plate 2 and then passes through the polarizing plate 2. . Accordingly, if the retardation value of the electrode substrate of the touch panel existing between the polarizing plate 1 and the polarizing plate 2 is small and the change in the phase difference of the linearly polarized light passing through the electrode substrate is small, coloring of the display image can be suppressed. it can. The coloring of the display image is conspicuous when the touch panel is viewed from an oblique direction. This is because the light emitted from the touch panel in the oblique direction is lighter than the light emitted in the front direction from the electrode substrate. It is presumed that this is because the passing distance when passing through the inside is long and the influence of retardation of the electrode substrate is more strongly affected. In the resin plate of the present invention, since the methyl methacrylate-styrene copolymer resin and the acrylic resin constituting the resin plate are both resins having a small intrinsic birefringence, before and after light passes through the resin plate. The change in retardation is small, and it is assumed that coloring of the display image on the liquid crystal display is suppressed.

  Moreover, in addition to good optical properties, the resin plate is also excellent in water absorption resistance and hardly warps in a high humidity environment. Although the usage environment of the touch panel may be under high humidity, the resin plate of the present invention is not easily warped under such an environment, and can be suitably used as a lower electrode substrate of the touch panel.

  The resin plate is suitably manufactured by laminating and integrating a methyl methacrylate-styrene copolymer resin layer and an acrylic resin layer laminated on both surfaces thereof by coextrusion molding. This co-extrusion molding is performed by melt-kneading the acrylic resin layer material and the methyl methacrylate-styrene copolymer resin layer material, respectively, using two or three uniaxial or biaxial extruders. It can be performed by laminating via a feed block die, a multi-manifold die or the like. The molten resin laminated and integrated may be cooled and solidified using, for example, a roll unit. A resin plate produced by coextrusion molding is preferable in that it is easier to perform secondary molding than a resin plate produced by bonding using an adhesive or an adhesive.

  Hereinafter, an embodiment for producing a resin plate by coextrusion molding will be described in detail with reference to FIG. As shown in the figure, first, the material of the acrylic resin layer and the material of the methyl methacrylate-styrene copolymer resin layer are heated and melted and kneaded by separate extruders 1 and 2, respectively. After being melt-laminated and integrated, the die 4 is extruded.

Next, the sheet-like or film-like molten resin extruded from the die 4 is sandwiched between the first cooling roll 5 and the second cooling roll 6 that face each other in the substantially horizontal direction, and is gently moved by the third cooling roll 7. The thickness of the resin plate 8 to be obtained can be adjusted by adjusting the thickness of the molten resin that can be cooled to obtain the resin plate 8, the distance between the first and second cooling rolls 5, 6, the peripheral speed, and the like. .

  At least one of the first and second cooling rolls 5 and 6 is connected to a rotation driving means such as a motor, and both rolls are configured to rotate at a predetermined peripheral speed. Among the two rolls, the second cooling roll 6 is a winding roll around which a sheet-like or film-like resin plate after being sandwiched between the two rolls is wound.

  Examples of the first and second cooling rolls 5 and 6 include a metal roll having rigidity and a metal elastic roll having elasticity. Examples of the metal roll include a drilled roll and a spiral roll. The metal elastic roll includes, for example, a shaft roll and a cylindrical metal thin film that is disposed so as to cover the outer peripheral surface of the shaft roll and is in contact with the molten resin, and between the shaft roll and the metal thin film. Examples include those in which a temperature-controlled fluid such as water or oil is enclosed, and those in which a metal belt is wound around the surface of a rubber roll.

  The 1st, 2nd cooling rolls 5 and 6 may be comprised by 1 type chosen from a metal roll and a metal elastic roll, and may be comprised combining a metal roll and a metal elastic roll.

  By combining a metal roll and a metal elastic roll, a resin plate having a reduced retardation value can be obtained. That is, when the molten resin is sandwiched between the metal roll and the metal elastic roll, the metal elastic roll elastically deforms in a concave shape along the outer peripheral surface of the metal roll via the molten resin, and the metal elastic roll and the metal roll are melted. Contact is made with a predetermined contact length through the resin. As a result, the metal roll and the metal elastic roll come into pressure contact with the molten resin by surface contact, and the molten resin sandwiched between these rolls is formed into a film while being uniformly pressed into a planar shape. As a result, distortion during film formation is reduced, and a resin plate having a reduced retardation value is obtained.

  Moreover, when combining a metal roll and a metal elastic roll, it is preferable to use the metal elastic roll as the first cooling roll 5 and the metal roll as the second cooling roll 6. Thereby, the retardation value (for example, Re (0) or Re (50)) of incident light at a wavelength of 590 nm of the obtained resin plate can be further reduced.

  The molten resin sandwiched between the first cooling roll 5 and the second cooling roll 6 is wound around the second cooling roll 6 and then taken up and taken up by the take-up roll. At this time, the third cooling roll 7 may be provided after the second cooling roll 6. Thereby, since molten resin is cooled slowly, the retardation value of the resin board obtained can be reduced. It does not specifically limit as a 3rd cooling roll, The normal metal roll conventionally used by extrusion molding is employable. Specific examples include a drilled roll and a spiral roll. The surface state of the third cooling roll 7 is preferably a mirror surface.

  When the third cooling roll 7 is provided, the molten resin wound around the second cooling roll 6 is passed between the second cooling roll 6 and the third cooling roll 7 and wound around the third cooling roll 7. To do. A predetermined gap may be provided between the second cooling roll 6 and the third cooling roll 7 so that the second cooling roll 6 and the third cooling roll 7 are in a released state or may be sandwiched between both rolls. A plurality of cooling rolls such as a fourth cooling roll, a fifth cooling roll,... Are provided after the third cooling roll 7, and the film wound around the third cooling roll 7 is sequentially wound around the next cooling roll. You may make it hang.

The resin plate is usually in the form of a sheet or film, and the thickness is usually 0.1 to 3 mm, preferably 0.1 to 2 mm, more preferably 0.1 to 1.5 mm. Preferably, it is 0.1-1 mm. Since the resin plate is composed of an acrylic resin layer and a methyl methacrylate-styrene copolymer resin layer, it is difficult to break and the thickness can be reduced. In this resin plate, the thickness of each acrylic resin layer laminated on both sides of the methyl methacrylate-styrene copolymer resin layer is preferably 0.1 mm or less, and is 0.005 to 0.1 mm. Is more preferably 0.01 to 0.1 mm, and particularly preferably 0.02 to 0.1 mm. If the thickness of the acrylic resin layer is too large, the resin plate may be easily warped in a high temperature and high humidity environment. On the other hand, if the thickness of the acrylic resin layer is too small, the surface hardness of the resin plate may be reduced. There is.
In addition, each thickness of the acrylic resin layers on both sides may be the same or different from each other. The thickness of the methyl methacrylate-styrene copolymer resin layer may be appropriately adjusted from the thickness of the entire resin plate and the thickness of the acrylic resin layer, but is preferably 70 to 99% of the thickness of the entire resin plate.

The resin plate preferably has Re (50) of 90 nm or less, more preferably 85 nm or less, and further preferably 80 nm or less. When Re (50) is 90 nm or less, coloring of a display image of the liquid crystal display can be further suppressed when a liquid crystal display provided with a touch panel using the resin plate as a lower electrode substrate is viewed from an oblique direction. it can. Re (50) is a retardation value when monochromatic light having a wavelength of 590 nm is incident at an angle of 50 ° with respect to the normal line of the resin plate surface.

The resin plate preferably has Re (0) of 60 nm or less, more preferably 57 nm or less, and further preferably 55 nm or less. When Re (0) is too large, when a liquid crystal display provided with a touch panel using the resin plate as a lower electrode substrate is viewed from the front, the display image of the liquid crystal display may appear colored. When Re (0) is 60 nm or less, coloring of the display image when the touch panel is viewed from the front direction can be suppressed. Re (0) is a retardation value when monochromatic light having a wavelength of 590 nm is incident at an angle of 0 ° with respect to the normal line of the resin plate surface.

From the viewpoint of suppressing coloring of the display image of the liquid crystal display when the screen of the touch panel is viewed from an oblique direction, the resin plate is expressed by the formula: | Re (0) −Re (50 ) | /50≦1.6 is preferably satisfied.
The value of | Re (0) −Re (50) | / 50 defined by this formula is more preferably 1.4 or less, and further preferably 1.2 or less. When Re (0) and Re (50) satisfy the relationship of the above formula, the display of the liquid crystal display when a liquid crystal display provided with a touch panel using the resin plate as a lower electrode substrate is viewed from an oblique direction. Coloring of the image can be further suppressed. | Re (0) −Re (50) | / 50 is a retardation value when monochromatic light having a wavelength of 590 nm is incident at an angle of 0 ° with respect to the normal line of the resin plate surface, and incident at an angle of 50 °. Represents the rate of change of the retardation value at the time, and when the rate of change exceeds 1.6, the color of the display image when viewing the touch panel from the front direction and the color of the display image when viewing from the diagonal direction The difference becomes large, and there is a risk that the coloring of the display image is more emphasized and visually recognized.
In order to satisfy the above formula, for example, a film-like product having a polycarbonate resin layer on both sides of an acrylic resin layer is melt-extruded from a die, sandwiched between a first cooling roll and a second cooling roll, and the second cooling The resin plate may be manufactured by winding it on a roll. From the viewpoint of reducing the value of | Re (0) −Re (50) | / 50, the first cooling roll is a metal elastic roll, and the second cooling roll is a metal. More preferably, it is a roll. In addition, you may provide a 3rd cooling roll after a 2nd cooling roll, Furthermore, you may provide a 4th cooling roll, a 5th cooling roll ..., and several rolls after a 3rd cooling roll.

  A resin plate having an acrylic resin layer on both sides of a methyl methacrylate-styrene copolymer resin layer, wherein Re (0) and Re (50) are represented by the formula: | Re (0) -Re (50) | / The resin plate satisfying 50 ≦ 1.6 has a retardation value when monochromatic light having a wavelength of 590 nm is incident at an angle of 0 ° with respect to the normal line of the resin plate surface, and a retardation when incident at an angle of 50 °. Since the rate of change with the value is within a predetermined range, the difference in coloring color is small when the resin plate is viewed from the front direction and when viewed from the oblique direction, and can be used for various display member applications. For example, it can be used as a surface protective plate for a liquid crystal display, a surface protective plate for a touch panel, or the like.

  At least one surface of the resin plate may be a mat surface having an uneven shape. When one surface of the resin plate is a mat surface, the mat surface is preferably a surface on the liquid crystal panel side, that is, a surface on which a transparent electrode film is not formed.

  The resin plate of the present invention thus obtained is preferably used as a lower electrode substrate. When using a resin plate as a lower electrode substrate, the lower electrode plate is manufactured by first cutting the resin plate into a required size and then providing a transparent electrode film on one surface of the resin plate.

The transparent electrode film is made of a metal oxide. Examples of the metal oxide include ATO (antimony / tin oxide) and ITO (indium / tin oxide). ITO is particularly preferable because of its excellent transparency. The thickness of the transparent electrode film is preferably 5 to 50 μm.
Examples of the method for producing the transparent electrode film include a vacuum deposition method, a sputtering method, an ionization deposition method, a CVD method, and the like.

  From the viewpoint of improving the adhesion between the resin plate and the transparent electrode film, the resin plate may be provided with a resin layer on the surface on which the transparent electrode film is formed. Any resin having excellent transparency may be used. The thickness of the resin layer is preferably 1 nm to 5 μm. If the thickness is less than 1 nm, the sufficient adhesion improvement effect may not be obtained. If the thickness exceeds 5 μm, a liquid crystal display with a touch panel using the resin plate as a lower electrode substrate is viewed from an oblique direction. The displayed image may appear colored.

The resistive film type touch panel is configured such that an upper electrode plate and a lower electrode plate are arranged to face each other through a spacer so that transparent electrode films of both electrode plates face each other.
When a touch panel is installed on the liquid crystal display, the lower electrode plate is installed in contact with the liquid crystal panel.

The upper electrode plate is produced by providing a transparent electrode film on one surface of the upper electrode substrate.
The resistive film type touch panel is energized when the pressed upper electrode plate comes into contact with the lower electrode plate, and the pressed position is detected. Therefore, the upper electrode substrate preferably has flexibility. From the viewpoint of flexibility, the thickness of the upper electrode substrate is preferably 10 to 400 μm.
As the upper electrode substrate, a resin film having excellent transparency is used, and usually polyethylene terephthalate is used. The resin plate of the present invention may be used for the upper electrode substrate, and both the upper electrode substrate and the lower electrode substrate may be used as the resin plate. In this case, the thicknesses of both resin plates may be the same or different from each other.

The resin plate is not limited to use as a lower electrode substrate of a resistive touch panel, but can also be used as an electrode substrate of another detection type touch panel, for example, a capacitive touch panel. . The capacitive touch panel is configured by forming a protective film on a transparent electrode film of an electrode plate having a transparent electrode film on one surface of an electrode substrate. When installing a capacitive touch panel on a liquid crystal display, the electrode substrate surface is placed in contact with the liquid crystal panel.
As this electrode substrate, a glass plate is usually used, but there is a problem that the glass plate is heavy and easily broken. By using the resin plate of the present invention instead of the glass plate, an electrode substrate that is light and difficult to break and has good optical properties can be obtained.

  Applications of the touch panel include a display window of a portable game machine, a display of a portable car navigation system and a portable information terminal, a bank ATM display, an industrial machine operation panel, and the like. The touch panel using the resin plate of the present invention as the lower electrode plate is lightweight because the lower electrode substrate is the resin plate of the present invention, and it is difficult to break, so by reducing the thickness of the resin plate The touch panel can be thinned and is preferably used as a portable application.

  Examples of the present invention will be described below, but the present invention is not limited thereto.

The structure of the extrusion apparatus used in the following examples and comparative examples is as follows.
Extruder 1: An extruder with a screw diameter of 65 mm, a single screw, and a vent (manufactured by Toshiba Machine Co., Ltd.) was used.
Extruder 2: An extruder with a screw diameter of 45 mm, a single screw, and a vent (manufactured by Hitachi Zosen Corporation) was used.
Feed block 3: A two-type three-layer distribution type feed block (manufactured by Hitachi Zosen) was used.
-Die 4: A T-die (manufactured by Hitachi Zosen Corporation) having a lip width of 1400 mm and a lip interval of 1 mm was used.
First, second, and third cooling rolls 5, 6, and 7: Horizontal type, cooling rolls having a surface length of 1400 mm and a diameter of 300 mmφ were used.

  More specifically, the first, second, and third cooling rolls 5, 6, and 7 are described. A metal elastic roll is used as the first cooling roll 5. As the metal elastic roll, a metal thin film is disposed so as to cover the outer peripheral surface of the shaft roll, and a fluid is sealed between the shaft roll and the metal thin film.

The shaft roll, metal thin film and fluid are as follows.
Shaft roll: Stainless steel metal thin film: Stainless steel mirror surface metal sleeve fluid of 2 mm thickness Fluid: Oil. By controlling the temperature of this oil, the temperature of the metal elastic roll can be controlled. More specifically, the oil was heated and cooled by ON / OFF control of a temperature controller so that the temperature could be controlled and circulated between the shaft roll and the metal thin film.

  Highly rigid metal rolls were used for the second and third cooling rolls 6 and 7. The metal roll is a stainless steel spiral roll having a mirror surface.

Resins used in Examples and Comparative Examples are the following three types.
Resin 1: A methacrylic resin “SUMIPEX EX” manufactured by Sumitomo Chemical Co., Ltd. having a heat distortion temperature (Th) of 100 ° C. was used.
Resin 2: A methyl methacrylate-styrene copolymer resin “Acryase MS” manufactured by Nippon Acrease Co., Ltd. having a heat distortion temperature (Th) of 90 ° C. was used. This methyl methacrylate-styrene copolymer resin contains 60% by weight of methyl methacrylate and 40% by weight of styrene as monomer units.
Resin 3: A polycarbonate resin “Caliver 301-10” manufactured by Sumitomo Dow Co., Ltd. having a heat distortion temperature (Th) of 140 ° C. was used.

[Examples 1 to 4 and Comparative Example 1]
<Production of resin plate>
First, extruders 1 and 2, feed block 3, die 4, first, second and third cooling rolls 5, 6 and 7 were arranged as shown in FIG. Next, the resin of the type shown in Table 1 as the resin layer A is melt-kneaded by the extruder 1, and the resin of the type shown in Table 1 as the resin layer B is melt-kneaded by the extruder 2, and each is supplied to the feed block. A film-like molten resin in which the resin layer B supplied from the extruder 2 to the feed block was laminated on both surfaces of the resin layer A supplied from the extruder 1 to the feed block was extruded from the die 4.

  Next, the film-like molten resin extruded from the die 4 is sandwiched between the first cooling roll 5 and the second cooling roll 6 that are arranged to face each other, and then wound around the third cooling roll 7 to be molded and cooled, A resin plate having a three-layer structure having the thickness shown in Table 1 in which the resin layer B was laminated on both surfaces of the resin layer A was obtained. In each of the obtained resin plates, the composition and thickness of each of the laminated resin layers B on both sides of the resin layer A are the same.

  In Table 1, “thickness” in the extruder 1 indicates the thickness of the resin layer A, “thickness” in the extruder 2 indicates each thickness of the resin layer B, and “total thickness” is obtained. The entire thickness of the obtained resin plate is shown.

<Evaluation>
About each obtained resin board, coloring when it sees from a retardation value and the diagonal direction was evaluated. Each evaluation method is shown below, and the results are also shown in Table 1.

[Retardation values (Re (0), Re (50))]
Using an automatic birefringence meter “KOBRA-WR” manufactured by Oji Scientific Instruments Co., Ltd., the retardation value (Re) when monochromatic light having a wavelength of 590 nm is incident at an angle of 0 ° with respect to the normal of the resin plate surface. (0)) and the retardation value (Re (50)) when incident at an angle of 50 °. Further, (| Re (0) −Re (50) | / 50) was determined from the values of Re (0) and Re (50).

[Coloring when viewed from an oblique direction]
The following evaluation was performed on the assumption that the obtained resin plate was used as a lower electrode substrate of a touch panel and the touch panel was further installed on a liquid crystal display.
First, one surface of the resin plate obtained above was overlaid on one surface of the first polarizing plate. Next, the second polarizing plate was superimposed on the other surface of the resin plate so that the first polarizing plate and the polarization axis were orthogonal to each other. As the first and second polarizing plates, “Sumikaran SG” manufactured by Sumitomo Chemical Co., Ltd. was used.

Then, while illuminating the surface of the second polarizing plate with the light of the three-wavelength fluorescent lamp (“Lupica Ace” manufactured by Mitsubishi Electric Osram Co., Ltd.), the second polarizing plate is viewed from an oblique direction of 45 degrees above the second polarizing plate surface. When the other surface of the resin plate was viewed, whether or not the surface appeared colored was visually observed. The following criteria were used.
○: Colored and invisible.
X: It looks colored.

[Comparative Example 2]
The types of resins shown in Table 1 were melted and kneaded by the extruder 1 and fed in the order of the feed block 3 and the die 4. Then, the molten resin extruded from the die 4 is sandwiched between the first cooling roll 5 and the second cooling roll 6 which are arranged to face each other, and then wound around the third cooling roll 7 to be molded and cooled. A single layer plate having the thickness shown was obtained.

  About the obtained single layer board, it carried out similarly to the said Example 1, and evaluated the coloring when it sees from a retardation value and the diagonal direction. The results are shown in Table 1.

1, 2 Extruder 3 Feed block 4 Die 5 First cooling roll 6 Second cooling roll 7 Third cooling roll 8 Resin plate

Claims (9)

  A resin plate for a lower electrode substrate, which is a resin plate used for a lower electrode substrate of a touch panel and has an acrylic resin layer on both sides of a methyl methacrylate-styrene copolymer resin layer.   Re (0) is the retardation value when monochromatic light with a wavelength of 590 nm is incident at an angle of 0 ° with respect to the normal of the resin plate surface, and Re (50) is the retardation value when incident at an angle of 50 °. The resin plate according to claim 1, wherein Re (0) and Re (50) satisfy the formula: | Re (0) −Re (50) | /50≦1.6.   3. The resin plate according to claim 1, wherein the retardation value Re (50) when monochromatic light having a wavelength of 590 nm is incident at an angle of 50 ° with respect to the normal line of the resin plate surface is 90 nm or less.   The resin plate according to any one of claims 1 to 3, wherein the acrylic resin layer has a thickness of 0.1 mm or less.   A film-like product having an acrylic resin layer on both sides of a methyl methacrylate-styrene copolymer resin layer is melt-extruded from a die, sandwiched between a first cooling roll and a second cooling roll, and wound around the second cooling roll. Then, the resin plate according to claim 1, wound around a third cooling roll.   The resin plate according to claim 5, wherein the first cooling roll is a metal elastic roll having a metal thin film on the outer peripheral portion, and the second cooling roll is a metal roll.   The lower electrode plate by which a transparent electrode film is provided in one surface of the resin plate in any one of Claims 1-6.   8. A touch panel configured by arranging a lower electrode plate and an upper electrode plate to face each other with a spacer interposed between the electrode plates so that the transparent electrode films face each other, wherein the lower electrode plate is defined in claim 7. Touch panel that is an electrode plate. A resin plate having an acrylic resin layer on both sides of a methyl methacrylate-styrene copolymer resin layer,
Re (0) is the retardation value when monochromatic light with a wavelength of 590 nm is incident at an angle of 0 ° with respect to the normal of the resin plate surface, and Re (50) is the retardation value when incident at an angle of 50 °. In this case, Re (0) and Re (50) satisfy the formula: | Re (0) −Re (50) | /50≦1.6.

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