JP2012178090A - 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 lower electrode substrate which is lightly weighted, which is hardly cracked, and which is excellent in environmental resistance characteristics for suppressing the generation of camber or undulation under high humidity, a lower electrode plate and a touch panel.SOLUTION: Disclosed is a resin plate for lower electrode substrate configured as a resin plate to be used for the lower electrode substrate of a touch panel consisting of a 5 layer structure in which a layer (B) made of methyl methacrylate/styrene copolymer resin and a layer (C) made of polycarbonate-based resin are laminated in this order on each of the both surfaces of a layer (A) made of polystyrene-based resin. Also, disclosed is a lower electrode plate configured such that a transparent electrode film is formed on one surface of the resin plate for lower electrode substrate and a touch panel using this 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.

  In Patent Document 2, a photocurable acrylic resin is applied in a predetermined pattern to a lower electrode plate using an acrylic resin plate as a lower electrode substrate, and then the resin is cured by irradiating with ultraviolet rays. In addition, it is described that an upper electrode plate is arranged through the spacer to constitute 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 inventor has 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, on each of both surfaces of a layer (A) made of polystyrene resin, a layer (B) made of methyl methacrylate-styrene copolymer resin, A resin plate for a lower electrode substrate having a five-layer structure in which a layer (C) made of a polycarbonate-based resin is laminated in this order.
(2) In the above (1), the methyl methacrylate-styrene copolymer resin contains 30 to 70% by weight of methyl methacrylate and 30 to 70% by weight of styrene monomer as monomer units. The resin plate for lower electrode substrates as described.
(3) 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 (1) or (2).
(4) 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 (3) 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 polystyrene resin, 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, polystyrene resins, methyl methacrylate-styrene copolymer resins, and polycarbonate resins all have a lower water absorption rate than acrylic resins, and thus warp and swell even when exposed to high humidity. hard. Among these three types of resins, the polystyrene resin is particularly small in water absorption. Further, the methyl methacrylate-styrene copolymer resin has high affinity for each of the polystyrene resin and the polycarbonate resin.

  The resin plate of the present invention comprises a layer (A) made of the above-mentioned polystyrene resin, and layers (B), (B) made of a methyl methacrylate-styrene copolymer resin laminated on both surfaces of this layer (A). ) And layers (C) and (C) made of polycarbonate-based resin laminated on the surfaces of these layers (B) and (B). That is, the resin plate of the present invention has a layer (B) made of a methyl methacrylate-styrene copolymer resin and a layer (C) made of a polycarbonate resin on both surfaces of a layer (A) made of a polystyrene resin. And a five-layer structure laminated in this order. When the resin plate is configured in such a specific laminated structure, that is, a laminated structure of layer (C) / layer (B) / layer (A) / layer (B) / layer (C), the above-described three kinds of resins are formed. Combined with the effects of each, it is lightweight and difficult to break, and the occurrence of warping and undulation under high humidity is suppressed, and it shows excellent environmental resistance characteristics, especially in high temperature and high humidity environment such as summer. There is an effect that the swell is reduced. Hereinafter, the resin plate of the present invention will be described in detail.

  The polystyrene resin constituting the layer (A) preferably contains 75 to 100% by weight of styrene monomer and 0 to 25% by weight of methyl methacrylate as monomer units. More preferably, the body contains 80-100% by weight and methyl methacrylate in a proportion of 0-20% by weight.

  In addition to styrene, substituted styrenes can be used as the styrene monomer. Examples of the substituted styrenes include halogenated styrenes such as chlorostyrene and bromostyrene, vinyl toluene, and α-methylstyrene. And alkyl styrenes. Two or more kinds of styrenic monomers can be used as necessary.

  Further, the polystyrene resin may contain a monomer other than the styrene monomer and methyl methacrylate as the monomer unit as necessary. The content of other monomers is usually about 10% by weight or less.

  Examples of monomers other than styrene monomers and methyl methacrylate that can be included as monomer units in polystyrene resins include, for example, ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, and methacrylic acid. Methacrylic acid esters other than methyl methacrylate such as benzyl, 2-ethylhexyl methacrylate, 2-hydroxyethyl methacrylate; methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate Acrylic acid esters such as 2-ethylhexyl acrylate and 2-hydroxyethyl acrylate; unsaturated acids such as methacrylic acid and acrylic acid; acrylonitrile, methacrylonitrile, maleic anhydride, phenyl Reimido, cyclohexyl maleimide, and the like, can also be used two or more thereof as needed. The layer (A) may contain a glutaric anhydride unit, a glutarimide unit, or the like.

  The methyl methacrylate-styrene copolymer resin constituting the layer (B) contains 30 to 70% by weight of methyl methacrylate and 30 to 70% by weight of styrene monomer as monomer units. More preferably, it contains 50 to 70% by weight of methyl methacrylate and 30 to 50% by weight of styrene monomer, and more methyl methacrylate than styrene monomer within the exemplified numerical range. It is preferable to include. Thereby, the adhesiveness of layer (B) and (C) improves, and generation | occurrence | production of delamination between layers (B) and (C) can be suppressed. Further, the ratio of the styrene monomer contained in the polystyrene resin constituting the layer (A) as a monomer unit is styrene contained in the methyl methacrylate-styrene copolymer resin constituting the layer (B). It is preferable that the value obtained by subtracting the latter ratio from the former ratio is 50% by weight or less than the ratio of the system monomer as a monomer unit. 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 may be used as the styrene monomer, and examples of the substituted styrenes include the same substituted styrenes as exemplified in the layer (A) described above.

  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 other monomers other than methyl methacrylate and styrene monomers that can be included as monomer units in the methyl methacrylate-styrene copolymer resin are the same as those exemplified in the layer (A) described above. These monomers are mentioned. Moreover, the layer (B) may contain a glutaric anhydride unit, a glutarimide unit, etc. similarly to the layer (A).

  On the other hand, examples of the polycarbonate resin constituting the layer (C) include those obtained by reacting a dihydric phenol and a carbonylating agent by an interfacial polycondensation method, a melt transesterification method, or the like, or 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 (C) preferably contains an acrylic resin in order to improve adhesion with the layer (B). Specifically, the layer (C) 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 (C), it is preferable to employ the same acrylic resin as that of the layer (B), that is, methyl methacrylate, and a low molecular weight one is more preferable. 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.

  Note that the composition of the layer (B) laminated on one surface of the layer (A) and the composition of the layer (B) laminated on the other surface of the layer (A) may be the same. It may be good or different. Similarly, the composition of the layer (C) laminated on the surface of one layer (B) and the composition of the layer (C) laminated on the surface of the other layer (B) are the same. May be different or different. The layers (A), (B), and (C) each contain one or more additives such as a light stabilizer, an ultraviolet absorber, an antioxidant, a flame retardant, and an antistatic agent, if necessary. Two or more kinds may be added.

  The resin plate is preferably manufactured by laminating and integrating by coextrusion molding so that the layer (B) and the layer (C) are laminated in this order on both sides of the layer (A). In this coextrusion molding, each material of layers (A), (B), and (C) is melt-kneaded using three uniaxial or biaxial extruders, and then a feed block die, a multi-manifold die, etc. It can carry out by laminating | stacking via. 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 materials of the layers (A), (B), and (C) are heated and melted and kneaded by separate extruders 1, 2, and 3, respectively. After being fed and melt laminated and integrated, it is extruded from the die 5.

  Next, the sheet-shaped or film-shaped molten resin extruded from the die 5 is sandwiched between the first cooling roll 6 and the second cooling roll 7 that are arranged to face each other in a substantially horizontal direction. At least one of the first and second cooling rolls 6 and 7 is connected to a rotational 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 7 is a winding roll around which a sheet-like or film-like resin plate is sandwiched between the two rolls.

  Examples of the first and second cooling rolls 6 and 7 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 6 and 7 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 having a reduced retardation value, the first and second cooling rolls 6 and 7 are preferably constituted by 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 6 and the metal roll as the second cooling roll 7. Thereby, the retardation value of the resin board obtained can be reduced more.

  The molten resin sandwiched between the first cooling roll 6 and the second cooling roll 7 described above is wound around the second cooling roll 7 and the third cooling roll 8 in this order. Specifically, the molten resin wound around the second cooling roll 7 is passed between the second cooling roll 7 and the third cooling roll 8 and wound around the third cooling roll 8. Thereby, since molten resin is cooled slowly, the retardation value of the resin board obtained can be reduced. Note that a predetermined gap may be provided between the second cooling roll 7 and the third cooling roll 8 so as to be in a released state, or the molten resin is sandwiched between the two rolls without providing the predetermined gap. May be.

  The third cooling roll 8 is not particularly limited, and an ordinary metal roll conventionally used in extrusion molding can be employed. Specific examples include a drilled roll and a spiral roll. The surface state of the third cooling roll 8 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 8, and sheet-like or film-like resin plates wound around the third cooling roll 8 are sequentially provided. It may be wound around the next cooling roll.

  The resin plate of the present invention can be obtained by winding the resin plate, which is wound around the third cooling roll 8 and slowly cooled, by a take-up roll (not shown) and winding it up. Since the resin plate has a five-layer structure in which the layer (B) and the layer (C) are laminated in this order 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 of the layer (B) and the layer (C) is preferably 0.005 to 0.1 mm, more preferably 0.01 to 0.1 mm. More preferably, it is from 05 to 0.1 mm. In particular, when the thickness of the layer (C) is too large, the display image of the liquid crystal display is colored 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. If the thickness is too small, the resin plate may be easily broken. Note that the thickness of the layer (B) stacked on one surface of the layer (A) and the thickness of the layer (B) stacked on the other surface of the layer (A) are the same. It may be different or different. Similarly, the thickness of the layer (C) laminated on the surface of the layer (B) laminated on one surface of the layer (A) and the other surface of the layer (A) are laminated. The thickness of the layer (C) laminated on the surface of the layer (B) may be the same as or different from each other.

  The thickness of the layer (A) is preferably 70 to 99% of the total thickness of the resin plate. The thicknesses of the layers (A), (B), and (C) and the thickness of the entire resin plate are adjusted by adjusting the thickness of the molten resin, the distance between the first and second cooling rolls 6 and 7, the peripheral speed, and the like. Can be adjusted by.

  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.
Extruder 3: An extruder with a screw diameter of 45 mm, a single screw, and a vent (manufactured by Hitachi Zosen Corporation) was used.
Feed block 4: A three-type five-layer distribution type feed block (manufactured by Hitachi Zosen Corporation) was used.
Die 5: 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 6, 7, and 8: Horizontal type, cooling rolls having a surface length of 1400 mm and a diameter of 300 mmφ were used.

  The first, second, and third cooling rolls 6, 7, and 8 will be described more specifically. A metal elastic roll is used as the first cooling roll 6. 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.

  High rigidity metal rolls were used for the second and third cooling rolls 7 and 8. 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: MS 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 4 and Comparative Examples 1 and 2]
<Production of resin plate>
First, extruders 1, 2, 3, feed block 4, die 5, first, second and third cooling rolls 6, 7, 8 were arranged as shown in FIG. 1. 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 is melt-kneaded in the extruder 2 as the layer (B). As shown in Table 1, the types of resins shown in Table 1 were melted and kneaded in the extruder 3, and each was supplied to the feed block 4.

  And the layers (B) and (B) supplied from the extruder 2 to the feed block 4 are laminated on both sides of the layer (A) supplied from the extruder 1 to the feed block 4, and these layers (B), A film-like molten resin in which the layers (C) and (C) supplied from the extruder 3 to the feed block 4 were laminated on each surface of (B) was extruded from the die 5.

  Next, the film-like molten resin extruded from the die 5 is sandwiched between the first cooling roll 6 and the second cooling roll 7 that are arranged to face each other, wound around the third cooling roll 8, and formed and cooled. A layer (B) and a layer (C) were laminated in this order on both sides of A), and a five-layered resin plate having the thickness shown in Table 1 was obtained. In each of the obtained resin plates, the compositions and thicknesses of the layers (B) and (B) laminated on both surfaces of the layer (A) are the same. Further, the layer (C) laminated on the surface of the layer (B) laminated on one surface of the layer (A) and the layer (B) laminated on the other surface of the layer (A) The composition and thickness of each layer (C) laminated on the surface are also the same.

  In addition, the surface temperature of the 1st cooling roll 6 was 120 degreeC, the surface temperature of the 2nd cooling roll 7 was 135 degreeC, and the surface temperature of the 3rd cooling roll 8 was 145 degreeC. These temperatures are values obtained by actually measuring the surface temperature of each cooling roll. “Thickness” in extruders 1, 2, and 3 in Table 1 indicates the thicknesses of the layers (A), (B), and (C), and “total thickness” indicates the obtained resin plate. The total thickness of is shown.

<Evaluation>
About each obtained resin board (Examples 1-4 and Comparative Examples 1 and 2), 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.

  In Examples 1 to 4, a layer (B) composed of a methyl methacrylate-styrene copolymer resin and a layer (C) composed of a polycarbonate resin are provided on both surfaces of the layer (A) composed of a polystyrene resin. Since it has a five-layer structure laminated in this order, it can be said that it is lighter and harder to break than the conventional glass plate for the reason described above.

  Further, as is clear from Table 1, in Examples 1 to 4, 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 4. There wasn't.

  On the other hand, Comparative Example 1 in which the layer (A) is made of a polymethyl methacrylate resin and Comparative Example 2 in which the layer (A) is made of a methyl methacrylate-styrene copolymer resin both show a large amount of warp displacement. It was. Moreover, as a result of visually observing the test piece after standing for 24 hours in a thermo-hygrostat set to a temperature of 40 ° C. and a humidity of 95%, the test piece of Comparative Example 1 was swelled.

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

Claims (4)

  A resin plate used for a lower electrode substrate of a touch panel, and a layer (B) made of a methyl methacrylate-styrene copolymer resin on each of both surfaces of a layer (A) made of a polystyrene resin, and a polycarbonate resin A resin plate for a lower electrode substrate having a five-layer structure in which a layer (C) made of is laminated in this order.   2. The lower electrode according to claim 1, wherein the methyl methacrylate-styrene copolymer resin contains 30 to 70 wt% of methyl methacrylate and 30 to 70 wt% of styrene monomer as monomer units. Resin plate for substrates.   A lower electrode plate comprising a transparent electrode film formed on one surface of the resin plate for a lower electrode substrate according to claim 1. 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 3.

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