JP2012178088A - Resin plate for lower electrode substrate, lower electrode plate, and touch panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin plate for a lower electrode substrate, the resin plate which is lightweight, hardly cracks and is excellent in environmental resistance characteristics suppressing warpage or distortion under a high humidity condition, and to provide a lower electrode plate and a touch panel.SOLUTION: The resin plate is to be used for a lower electrode substrate of a touch panel, and comprises a layer (A) made of a methyl methacrylate-styrene copolymer resin and a layer (B) made of a polycarbonate resin laminated on both surfaces of the layer (A). The lower electrode plate comprises the resin plate for a lower electrode substrate and a transparent electrode film formed on one surface of the resin plate. The touch panel uses the lower electrode plate.

Description

  The present invention relates to a resin plate used for a lower electrode substrate of a touch panel, and a lower electrode plate and a touch panel formed using the resin plate.

  Conventionally, a resistive film type touch panel is known. A resistive touch panel has a lower electrode plate and an upper electrode plate, each of which has a transparent electrode film formed on one side of a substrate, with a spacer interposed between the electrode plates 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, it is common to first place a touch panel on the liquid crystal panel, and then place a quarter-wave plate, a polarizing plate, and a display protection plate in this order on the touch panel. It is.

  In Patent Document 1, a substrate of a lower electrode plate (that is, a lower electrode substrate) that is an electrode plate in contact with a liquid crystal panel among two electrode plates constituting a resistive film type touch panel is formed of a glass plate. A touch panel is described in which the substrate of the upper electrode plate (that is, the upper electrode substrate) which is the other electrode plate in contact with the / 4 wavelength plate is formed of a polyethylene terephthalate resin plate.

  However, the touch panel described in Patent Document 1 has a problem that the lower electrode substrate is heavy and easily broken because the lower electrode substrate is made of a glass plate.

Patent Document 2 describes that an acrylic resin plate is used for a lower electrode substrate of a touch panel.
However, when the lower electrode substrate is made of an acrylic resin plate as described in Patent Document 2, there is a problem that warpage and undulation occur in a high humidity environment.

JP 2006-277769 A JP 2006-306951 A

  An object of the present invention is to provide a resin plate for a lower electrode substrate, a lower electrode plate, and a touch panel, which are light and difficult to break, and have excellent environmental resistance characteristics in which warpage and undulation are suppressed under high humidity.

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 used for a lower electrode substrate of a touch panel, wherein a layer (B) made of a polycarbonate resin is laminated on both sides of a layer (A) made of a methyl methacrylate-styrene copolymer resin. A resin plate for a lower electrode substrate.
(2) In the above (1), the methyl methacrylate-styrene copolymer resin contains 30 to 90% by weight of methyl methacrylate and 10 to 70% by weight of styrene monomer as monomer units. The resin plate for lower electrode substrates as described.
(3) The resin plate for a lower electrode substrate according to (1) or (2), wherein the thickness of each of the layers (B) is 0.005 to 0.1 mm.
(4) A lower electrode plate in which a transparent electrode film is formed on one surface of the resin plate for a lower electrode substrate according to any one of (1) to (3).
(5) A lower electrode plate in which a transparent electrode film is formed on one surface of the lower electrode substrate, and an upper electrode plate in which a transparent electrode film is formed on one surface of the upper electrode substrate are mutually transparent electrodes. A touch panel configured to be opposed to each other with a spacer interposed between a lower electrode plate and an upper electrode plate so that the films face each other, wherein the lower electrode plate is the lower electrode according to (4) A touch panel made of plates.

  According to the resin plate for a lower electrode substrate of the present invention, there are effects that it is light and difficult to break and has excellent environmental resistance characteristics. Therefore, if a transparent electrode film is formed on one surface of the lower electrode substrate made of this resin plate to form a lower electrode plate and this is used to construct a touch panel, the surface of the touch panel can be effectively protected even in various environments. can do.

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”) is composed of a methyl methacrylate-styrene copolymer resin and a polycarbonate resin. All of these resins are lighter than glass. In addition, the polycarbonate-based resin is excellent in impact resistance and is not easily broken. Furthermore, both of the methyl methacrylate-styrene copolymer resin and the polycarbonate-based resin have a lower water absorption rate than the acrylic resin, and therefore, warpage and undulation hardly occur even when exposed to high humidity.

  The resin plate of the present invention has a laminated structure in which a layer (B) made of a polycarbonate-based resin is laminated on both sides of a layer (A) made of the above-mentioned methyl methacrylate-styrene copolymer resin. When the resin plate is configured with such a specific laminated structure, the effects of each of the methyl methacrylate-styrene copolymer resin and the polycarbonate resin described above are combined, and are lightweight and difficult to break, and warp under high humidity. Occurrence of undulation is suppressed, and excellent environmental resistance characteristics are exhibited. In particular, there is an effect that warpage and undulation are reduced in a high temperature and high humidity environment such as summer. Hereinafter, the resin plate of the present invention will be described in detail.

  The methyl methacrylate-styrene copolymer resin constituting the layer (A) contains 30 to 90% by weight of methyl methacrylate and 10 to 70% by weight of styrene monomer as monomer units. More preferably, it contains 50 to 85% by weight of methyl methacrylate and 15 to 50% by weight of styrene monomer, and 60 to 80% by weight of methyl methacrylate and 20 to 20% of styrene monomer. More preferably, it is contained in a proportion of 40% by weight, and it is preferred that methyl methacrylate is contained in a larger amount than the styrene monomer within the exemplified numerical range. Thereby, the adhesiveness of layer (A) and (B) improves, and generation | occurrence | production of delamination between layers (A) and (B) can be suppressed.

  In addition to styrene, substituted styrenes can be used as the styrenic monomer. Examples of the substituted styrenes include halogenated styrenes such as chlorostyrene and bromostyrene, vinyltoluene, and α-methyl. Examples thereof include alkylstyrenes such as styrene. Two or more kinds of styrenic monomers can be used as necessary.

  Moreover, the methyl methacrylate-styrene copolymer resin may contain monomers other than methyl methacrylate and styrene monomers as necessary as monomer units. The content of other monomers is usually about 10% by weight or less.

  Examples of the other monomer include other than methyl methacrylate such as ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2-ethylhexyl methacrylate, 2-hydroxyethyl methacrylate. Methacrylic acid esters; acrylic acid esters such as methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate; Examples include unsaturated acids such as acid and acrylic acid; acrylonitrile, methacrylonitrile, maleic anhydride, phenylmaleimide, cyclohexylmaleimide, etc. It can also be. The layer (A) may contain a glutaric anhydride unit, a glutarimide unit, or the like.

  On the other hand, examples of the polycarbonate resin constituting the layer (B) include those obtained by reacting a dihydric phenol and a carbonylating agent by an interfacial polycondensation method, a melt transesterification method, or the like, as well as a carbonate prepolymer. Examples thereof include those obtained by polymerizing by a phase transesterification method and those obtained by polymerizing a cyclic carbonate compound by a ring-opening polymerization method.

  Examples of the dihydric phenol include hydroquinone, resorcinol, 4,4′-dihydroxydiphenyl, bis (4-hydroxyphenyl) methane, bis {(4-hydroxy-3,5-dimethyl) phenyl} methane, 1,1- Bis (4-hydroxyphenyl) ethane, 1,1-bis (4-hydroxyphenyl) -1-phenylethane, 2,2-bis (4-hydroxyphenyl) propane (commonly called bisphenol A), 2,2-bis { (4-hydroxy-3-methyl) phenyl} propane, 2,2-bis {(4-hydroxy-3,5-dimethyl) phenyl} propane, 2,2-bis {(4-hydroxy-3,5-dibromo) ) Phenyl} propane, 2,2-bis {(3-isopropyl-4-hydroxy) phenyl} propane, 2,2-bis {( -Hydroxy-3-phenyl) phenyl} propane, 2,2-bis (4-hydroxyphenyl) butane, 2,2-bis (4-hydroxyphenyl) -3-methylbutane, 2,2-bis (4-hydroxyphenyl) ) -3,3-dimethylbutane, 2,4-bis (4-hydroxyphenyl) -2-methylbutane, 2,2-bis (4-hydroxyphenyl) pentane, 2,2-bis (4-hydroxyphenyl)- 4-methylpentane, 1,1-bis (4-hydroxyphenyl) cyclohexane, 1,1-bis (4-hydroxyphenyl) -4-isopropylcyclohexane, 1,1-bis (4-hydroxyphenyl) -3,3 , 5-trimethylcyclohexane, 9,9-bis (4-hydroxyphenyl) fluorene, 9,9-bis {(4-hydroxy -3-methyl) phenyl} fluorene, α, α′-bis (4-hydroxyphenyl) -o-diisopropylbenzene, α, α′-bis (4-hydroxyphenyl) -m-diisopropylbenzene, α, α′- Bis (4-hydroxyphenyl) -p-diisopropylbenzene, 1,3-bis (4-hydroxyphenyl) -5,7-dimethyladamantane, 4,4′-dihydroxydiphenylsulfone, 4,4′-dihydroxydiphenylsulfoxide, 4,4′-dihydroxydiphenyl sulfide, 4,4′-dihydroxydiphenyl ketone, 4,4′-dihydroxydiphenyl ether, 4,4′-dihydroxydiphenyl ester, and the like, and two or more of them are used as necessary. You can also

  Among them, bisphenol A, 2,2-bis {(4-hydroxy-3-methyl) phenyl} propane, 2,2-bis (4-hydroxyphenyl) butane, 2,2-bis (4-hydroxyphenyl) -3 -Methylbutane, 2,2-bis (4-hydroxyphenyl) -3,3-dimethylbutane, 2,2-bis (4-hydroxyphenyl) -4-methylpentane, 1,1-bis (4-hydroxyphenyl) It is preferable to use a dihydric phenol selected from −3,3,5-trimethylcyclohexane and α, α′-bis (4-hydroxyphenyl) -m-diisopropylbenzene alone or in combination of two or more. Of 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane and bisphenol A, one or more dihydric phenols selected from 2,2-bis {(4-hydroxy-3-methyl) phenyl} propane and α, α′-bis (4-hydroxyphenyl) -m-diisopropylbenzene Use in combination is preferred.

  Examples of the carbonylating agent include carbonyl halides such as phosgene, carbonate esters such as diphenyl carbonate, haloformates such as dihaloformates of dihydric phenols, and two or more of them can be used as necessary.

  The layer (B) preferably contains an acrylic resin in order to improve the adhesion with the layer (A). Specifically, the layer (B) is preferably composed of a polycarbonate resin composition containing 0.01 to 1 part by weight of an acrylic resin with respect to 100 parts by weight of the polycarbonate resin.

  As the acrylic resin contained in the layer (B), it is preferable to employ the same acrylic resin as that of the layer (A), that is, methyl methacrylate, and more preferably a low molecular weight one. The preferred molecular weight range is 1,000 to 100,000. If the molecular weight is too low, the acrylic resin volatilizes during extrusion molding. If the molecular weight is too high, the acrylic resin may cause phase separation with the polycarbonate resin, and the light transmittance may be reduced.

  In addition, each composition of the layer (B) laminated | stacked on both surfaces of a layer (A) may mutually be the same, and may differ. 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 layers (A) and (B) as necessary. May be.

  The resin plate is suitably manufactured by laminating and integrating the layer (A) and the layer (B) laminated on both surfaces by coextrusion molding. In this coextrusion molding, the material of the layer (A) and the material of the layer (B) are melt-kneaded using a two or three uniaxial or biaxial extruder, respectively. This can be done by stacking via a 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 the resin plate of the present invention by coextrusion molding will be described in detail with reference to FIG. As shown in the figure, first, the material of the layer (A) and the material of the layer (B) are heated and melted and kneaded by separate extruders 1 and 2, respectively, supplied to the feed block 3 and melted. After stacking and integrating, the die 4 is extruded.

  Next, the sheet-shaped or film-shaped 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 in a substantially horizontal direction. 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.

  When obtaining a resin plate with a reduced retardation value, the first and second cooling rolls 5 and 6 are preferably composed of a combination of a metal roll and a metal elastic roll. 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.

  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 of the resin board obtained can be reduced more.

  The molten resin sandwiched between the first cooling roll 5 and the second cooling roll 6 described above is wound around the second cooling roll 6 and the third cooling roll 7 in this order. Specifically, 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. Thereby, since molten resin is cooled slowly, the retardation value of the resin board obtained can be reduced. It should be noted that a predetermined gap may be provided between the second cooling roll 6 and the third cooling roll 7 so as to be released, or the molten resin is sandwiched between the two rolls without providing the predetermined gap. May be.

  As the 3rd cooling roll 7, it does not specifically limit and 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. A plurality of cooling rolls such as a fourth cooling roll, a fifth cooling roll,... Are provided after the third cooling roll 7, and sheet-like or film-like resin plates wound around the third cooling roll 7 are sequentially provided. It may be wound around the next cooling roll.

  A resin plate of the present invention can be obtained by winding a resin plate that is wound around the third cooling roll 7 and slowly cooling it with a take-up roll (not shown) and winding it up. Since the resin plate has a laminated structure in which the layer (B) is laminated on both sides of the layer (A), it is difficult to break and the thickness can be reduced. 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, and still more preferably 0.1. ~ 1 mm.

  In this resin plate, the thickness of each layer (B) laminated on both surfaces of the layer (A) is preferably 0.005 to 0.1 mm, and preferably 0.01 to 0.1 mm. More preferably, it is 0.05-0.1 mm. If the thickness of the layer (B) is too large, the display image of the liquid crystal display may appear colored when the liquid crystal display provided with a touch panel using the resin plate as the lower electrode substrate is viewed from an oblique direction. If the thickness is too small, the resin plate may be easily broken. Note that the thicknesses of the layers (B) on both sides may be the same or different.

  The thickness of the layer (A) is preferably 70 to 99% of the total thickness of the resin plate. The thickness of the layers (A) and (B) and the thickness of the entire resin plate can be adjusted by adjusting the thickness of the molten resin, the distance between the first and second cooling rolls 5 and 6, the peripheral speed, and the like. it can.

  Note that 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 used as a lower electrode substrate for a touch panel. When the resin plate is used as the lower electrode substrate, the resin plate is first cut into a required size, and then a transparent electrode film is formed 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), and 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 forming the transparent electrode film on one surface of the resin plate include a vacuum vapor deposition method, a sputtering method, an ionization vapor deposition method, and a CVD method.

  From the viewpoint of improving the adhesion between the resin plate and the transparent electrode film, a resin layer may be provided on one surface of the resin plate on which the transparent electrode film is formed. As resin which comprises this resin layer, what is excellent in transparency is preferable. The thickness of the resin layer is preferably 1 nm to 5 μm. If the thickness of the resin layer is too thin, there is a possibility that a sufficient adhesion improving effect cannot be obtained. Also, if the thickness of the resin layer is too large, the display image of the liquid crystal display may appear colored when the liquid crystal display with the touch panel using the resin plate as the lower electrode substrate is viewed from an oblique direction. is there.

  The lower electrode substrate formed using the resin plate of the present invention can be suitably used for a resistive film type touch panel. 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 this touch panel is installed on the liquid crystal display, the lower electrode plate is installed in contact with the liquid crystal panel.

  On the other hand, the upper electrode plate in the resistive touch panel is manufactured by forming 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 this 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 composed of the resin plate of the present invention. In this case, the thicknesses of both resin plates may be the same or different from each other.

  The resin plate of the present invention 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. Can do. The capacitive touch panel is configured by forming a protective film on a transparent electrode film of an electrode plate in which a transparent electrode film is formed on one surface of an electrode substrate. When installing a capacitive touch panel on the 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. Therefore, this problem can be improved by using the resin plate of the present invention instead of the glass plate.

  Examples of the use 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, an ATM display of a bank, an operation panel of an industrial machine, and the like. The touch panel using the resin plate of the present invention as the lower electrode plate is light in weight because the lower electrode substrate is the resin plate of the present invention, and more difficult to break, so by reducing the thickness of the resin plate. The touch panel can be thinned, and is particularly preferably used as a portable application.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited by these Examples.

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.
Axial roll: stainless steel one was used.
Metal thin film: A stainless steel mirror metal sleeve having a thickness of 2 mm was used.
-Fluid: Oil. By controlling the temperature of the 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 the examples and comparative examples are the following four types.
Resin 1: A polycarbonate resin “Caliver 301-10” manufactured by Sumitomo Dow Co., Ltd. having a heat distortion temperature (Th) of 140 ° C. was used.
Resin 2: A methyl methacrylate-styrene copolymer resin “Estyrene MS600” manufactured by Nippon Steel Chemical Co., Ltd. having a heat distortion temperature (Th) of 100 ° C. was used. This methyl methacrylate-styrene copolymer resin contains 60% by weight of methyl methacrylate and 40% by weight of styrene monomer as monomer units.
Resin 3: A methyl methacrylate-styrene copolymer resin “Estyrene MS200” manufactured by Nippon Steel Chemical Co., Ltd. having a heat distortion temperature (Th) of 100 ° C. was used. This methyl methacrylate-styrene copolymer resin contains 20% by weight of methyl methacrylate as monomer units and 80% by weight of styrene monomer.
Resin 4: A polymethyl methacrylate (PMMA) resin “SUMIPEX MHF” manufactured by Sumitomo Chemical Co., Ltd. having a heat distortion temperature (Th) of 100 ° C. was used.

[Examples 1 to 5 and Comparative Examples 1 and 2]
<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, a resin of the type shown in Table 1 as the layer (A) is melt-kneaded in the extruder 1, and a resin of the type shown in Table 1 as the layer (B) is melt-kneaded in the extruder 2, respectively. The film-like molten resin in which the layer (B) supplied from the extruder 2 to the feed block 3 is laminated on both sides of the layer (A) supplied from the extruder 1 to the feed block 3 is die 4. Extruded from.

  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 which are arranged to face each other, wound around the third cooling roll 7, molded and cooled, and the layer ( A resin plate having a three-layer structure having the thickness shown in Table 1 in which the layer (B) was laminated on both sides of A) was obtained. The composition and thickness of the layers (B) on both sides of each obtained resin plate are the same.

  In addition, the surface temperature of the 1st cooling roll 5 was 120 degreeC, the surface temperature of the 2nd cooling roll 6 was 135 degreeC, and the surface temperature of the 3rd cooling roll 7 was 145 degreeC. These temperatures are values obtained by actually measuring the surface temperature of each cooling roll. In Table 1, “Thickness” in the extruders 1 and 2 indicates the thickness of each of the layers (A) and (B), and “Total thickness” indicates the total thickness of the obtained resin plate. Yes.

<Evaluation>
About each obtained resin board (Examples 1-5 and Comparative Examples 1 and 2), the curvature evaluation under high humidity was performed. The evaluation method is shown below, and the results are shown in Table 1.

(Warness evaluation method under high humidity)
First, a test piece was cut out from the resin plate. The shape of the test piece was 20 cm □. The test piece was placed on a surface plate with the convex warped surface facing downward, and the amount of lift at the four corners was measured with a position sensor, and the average value of the measured values was taken as the initial warpage amount.

  Next, the test piece was allowed to stand for 24 hours in a thermo-hygrostat set to a temperature of 40 ° C. and a humidity of 95%. Thereafter, the amount of lift of the four corners of the test piece was measured in the same manner as the initial warpage amount, and the amount of high humidity warpage was determined. Then, the amount of warpage was calculated by applying the initial warpage amount and the high humidity warpage amount to the formula: high humidity warpage amount−initial warpage amount.

  Since Examples 1-5 have the structure by which the layer (B) which consists of polycarbonate resin is laminated | stacked on both surfaces of the layer (A) which consists of methyl methacrylate-styrene copolymer resin, from the reason mentioned above, It can be said that it is lighter than conventional glass plates and difficult to break. In addition, as can be seen from Table 1, in Examples 1 to 5, since the amount of warpage displacement is small, it can be seen that the occurrence of warpage under high humidity is suppressed. Furthermore, as a result of visually observing the test pieces after standing for 24 hours in a thermo-hygrostat set to a temperature of 40 ° C. and a humidity of 95%, the swell was generated in each of the test pieces of Examples 1 to 5. There wasn't.

  In the test piece of Example 5, delamination occurred in a part between each of the layers (B) on both sides and the layer (A). The reason for this is presumed to be that in the methyl methacrylate-styrene copolymer resin constituting the layer (A), the proportion of the styrene monomer is larger than the proportion of methyl methacrylate.

  On the other hand, Comparative Example 1 in which the layer (A) is made of polymethyl methacrylate resin and Comparative Example 2 in which the layers (A) and (B) are both made of polymethyl methacrylate resin show a large amount of warpage displacement. It was. In addition, as a result of visual observation of the test piece after standing for 24 hours in a thermo-hygrostat set to a temperature of 40 ° C. and a humidity of 95%, each test piece of Comparative Examples 1 and 2 was swelled. It was.

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

Claims (5)

  A resin plate used for a lower electrode substrate of a touch panel, wherein a layer (B) made of a polycarbonate-based resin is laminated on both sides of a layer (A) made of a methyl methacrylate-styrene copolymer resin. A resin plate for a lower electrode substrate.   The lower electrode according to claim 1, wherein the methyl methacrylate-styrene copolymer resin contains, as monomer units, 30 to 90% by weight of methyl methacrylate and 10 to 70% by weight of styrene monomer. Resin plate for substrates.   The resin plate for a lower electrode substrate according to claim 1 or 2, wherein each of the layers (B) has a thickness of 0.005 to 0.1 mm.   The lower electrode plate by which a transparent electrode film is formed in one surface of the resin plate for lower electrode substrates in any one of Claims 1-3. A lower electrode plate in which a transparent electrode film is formed on one surface of the lower electrode substrate;
An upper electrode plate in which a transparent electrode film is formed on one surface of the upper electrode substrate,
It is a touch panel that is configured to face each other with a spacer interposed between the lower electrode plate and the upper electrode plate so that the transparent electrode films face each other,
The touch panel which the said lower electrode plate consists of a lower electrode plate of Claim 4.

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