JP5525390B2 - Thermoplastic resin extrusion board - Google Patents

Description

  The present invention relates to a thermoplastic resin extruded plate that hardly warps and deforms.

  Thermoplastic resin extruded plates (hereinafter sometimes referred to as “extruded plates”) are excellent in continuous productivity, plate thickness accuracy, etc., and are used in various fields such as home appliances, automobiles, building materials, and electronic equipment. Various types of resin are used.

  On the other hand, there is a problem that the extruded plate is easily warped and deformed when used in a severe environment such as high temperature and high humidity. This problem is remarkable in applications related to electronic devices such as a light guide plate, a diffusion plate, a touch panel substrate, and a liquid crystal display protection plate that are used under high temperature or high humidity. Therefore, an attempt has been made to suppress warping deformation of the resin plate that occurs in the use environment.

Patent Document 1 discloses a resin obtained by laminating a resin layer containing methyl methacrylate units and styrene monomer units at a predetermined ratio and a resin layer containing methyl methacrylate units and an ultraviolet absorber at a predetermined ratio. A laminate is described. According to Patent Document 1, this resin laminate is described as being hardly deformed by water absorption and excellent in weather resistance.
However, Patent Document 1 does not discuss the suppression of warpage deformation of the resin laminate in a high temperature and high humidity environment.

  Patent Document 2 discloses a transparent thermoplastic resin composite sheet in which at least one surface of a transparent thermoplastic resin sheet is coated with a cured resin layer through an adhesive layer, and the birefringence values in the thickness direction and in the surface are within a predetermined range. Is described. According to Patent Document 2, it is described that the composite sheet is unlikely to be warped and deformed in a use environment or the like.

  However, when the birefringence value is reduced, the internal strain is reduced and the warpage tends to be difficult. However, even if the birefringence value is small, there are many cases in which warpage deformation occurs depending on the use environment. Therefore, the composite sheet described in Patent Document 2 has insufficient suppression of warp deformation.

Japanese Patent Laid-Open No. 2004-9524 JP 2005-193514 A

  The subject of this invention is providing the thermoplastic resin extrusion board which can suppress the curvature deformation in a high-temperature, high-humidity environment.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have found a solution means having the following constitution and have completed the present invention.
(1) A molten thermoplastic resin extruded from a die is sandwiched between a first cooling roll and a second cooling roll, wound around the second cooling roll, and then wound around at least one subsequent cooling roll. It is a thermoplastic resin extrusion plate obtained by hanging, the other surface opposite to the one surface contacting the outer peripheral surface of the second cooling roll is curved, the center of curvature is located on the other surface side, the curved A thermoplastic resin extruded plate characterized in that the direction is at least one of an extrusion direction and a direction orthogonal to the extrusion direction, and a radius of curvature is 10 to 200 m.
(2) The thermoplastic resin is at least one selected from a methyl methacrylate resin, an aromatic polycarbonate resin, a styrene resin, and a resin containing an alicyclic structure-containing ethylenically unsaturated monomer unit. The thermoplastic resin extruded plate according to (1).
(3) The thermoplastic resin is formed by laminating at least two kinds of thermoplastic resins, and the laminated thermoplastic resins are methyl methacrylate resin, aromatic polycarbonate resin, styrene resin, and alicyclic ring. The thermoplastic resin extruded plate according to (1) or (2), which is at least one selected from resins containing a structure-containing ethylenically unsaturated monomer unit.
(4) The thermoplastic resin extruded plate according to any one of (1) to (3), wherein the thickness is 0.3 to 5 mm.
(5) The thermoplastic resin extruded plate according to any one of (1) to (4), which is used for a light guide plate.
(6) The thermoplastic resin extruded plate according to any one of (1) to (4), which is used for a touch panel substrate.
(7) The thermoplastic resin extruded plate according to any one of (1) to (4), which is used for a liquid crystal display protective plate.

  Since the thermoplastic resin extrusion plate of the present invention is not easily warped and deformed in a high temperature and high humidity environment, the thermoplastic resin extruded plate is preferably used for a light guide plate, a touch panel substrate, a liquid crystal display protective plate, etc., where the usage environment is high temperature or high humidity. it can.

It is a schematic explanatory drawing which shows the manufacturing method of the thermoplastic resin extrusion board concerning one Embodiment of this invention. It is a partial expansion schematic explanatory drawing of FIG. (A), (b) is a schematic explanatory drawing which shows the thermoplastic resin extrusion board concerning one Embodiment of this invention.

  The thermoplastic resin extruded plate of the present invention is made of a thermoplastic resin. The thermoplastic resin is not particularly limited as long as it is a melt processable resin. For example, polyvinyl chloride resin, acrylonitrile-butadiene-styrene resin, low density polyethylene resin, high density polyethylene resin, linear low density polyethylene resin, polystyrene resin. , Polypropylene resin, acrylonitrile-styrene resin, cellulose acetate resin, ethylene-vinyl acetate resin, acrylic-acrylonitrile-styrene resin, acrylic-chlorinated polyethylene resin, ethylene-vinyl alcohol resin, fluorine resin, methyl methacrylate resin, methyl methacrylate -Styrene resin, polyacetal resin, polyamide resin, polyethylene terephthalate resin, aromatic polycarbonate resin, polysulfone resin, polyethersulfone resin, methylpente In addition to general-purpose or engineering plastics such as resins, polyarylate resins, polybutylene terephthalate resins, resins containing alicyclic structure-containing ethylenically unsaturated monomer units, polyphenylene sulfide resins, polyphenylene oxide resins, polyether ether ketone resins, etc. , Polyvinyl chloride elastomer, chlorinated polyethylene, ethylene-ethyl acrylate resin, thermoplastic polyurethane elastomer, thermoplastic polyester elastomer, ionomer resin, styrene-butadiene block polymer, ethylene-propylene rubber, polybutadiene resin, acrylic rubber, etc. A rubber-like polymer is mentioned, 1 type may be used among these and 2 or more types may be mixed and used.

  Among these, at least one selected from a methyl methacrylate resin, an aromatic polycarbonate resin, a styrene resin, and a resin containing an alicyclic structure-containing ethylenically unsaturated monomer unit because of its good optical properties. Is preferred. Further, the thermoplastic resin may be constituted by laminating at least two kinds of thermoplastic resins. That is, the extruded plate of the present invention may have a laminated structure having two or more thermoplastic resin layers by melt-kneading and coextruding two or more thermoplastic resins using two or more extruders. In this case, the thermoplastic resin constituting each laminated thermoplastic resin layer is a methyl methacrylate resin, an aromatic polycarbonate resin, a styrene resin, and an alicyclic structure-containing ethylenically unsaturated monomer unit. It is preferably at least one selected from resins containing.

  The methyl methacrylate resin is a polymer containing 50% by weight or more of methyl methacrylate units as monomer units. The content of methyl methacrylate units is preferably 70% by weight or more, and may be 100% by weight. The polymer having a methyl methacrylate unit of 100% by weight is a methyl methacrylate homopolymer obtained by polymerizing methyl methacrylate alone.

  The methyl methacrylate resin may be a copolymer of methyl methacrylate and another monomer that can be copolymerized with the methyl methacrylate. Examples of other monomers that can be copolymerized with methyl methacrylate include methacrylic acid esters other than methyl methacrylate. Examples of the methacrylic acid esters include ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2-ethylhexyl methacrylate, 2-hydroxyethyl methacrylate and the like. In addition, acrylic esters such as methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, methacrylic acid, acrylic acid Unsaturated acids such as, halogenated styrenes such as chlorostyrene and bromostyrene, substituted styrenes such as vinyltoluene and alkylstyrenes such as α-methylstyrene, acrylonitrile, methacrylonitrile, maleic anhydride, phenylmaleimide, cyclohexyl A maleimide etc. are also mentioned. Such monomers may be used alone or in combination of two or more.

  The methyl methacrylate resin may be a resin composition by adding a rubbery polymer. Thereby, since it becomes difficult to crack at the time of shaping | molding, a yield can be improved. Examples of the rubber-like polymer include an acrylic multilayer polymer, and a graft copolymer obtained by graft-polymerizing an ethylenically unsaturated monomer in a proportion of 95 to 20 parts by weight to 5 to 80 parts by weight of a rubber-like polymer. Etc.

  Examples of the acrylic multilayer structure polymer include those having a rubber elastic layer or an elastomer layer in an amount of 20 to 60 parts by weight and having a hard layer at the outermost layer, and further having a hard layer as the innermost layer. You may do it.

  The rubber elastic layer or the elastomer layer is a layer of an acrylic polymer having a glass transition point (Tg) of less than 25 ° C., for example, lower alkyl acrylate and methacrylate, lower alkoxy acrylate, cyanoethyl acrylate, acrylamide, and hydroxy lower alkyl acrylate. And a polymer obtained by crosslinking one or more monoethylenically unsaturated monomers such as hydroxy lower methacrylate, acrylic acid and methacrylic acid with allyl methacrylate or polyfunctional monomer.

  The hard layer is a layer of an acrylic polymer having a Tg of 25 ° C. or higher, and is composed of alkyl methacrylate having an alkyl group having 1 to 4 carbon atoms alone or as a main component, and other alkyl methacrylate, alkyl acrylate, styrene, substituted It may be a cross-linked polymer composed of a copolymer of a monofunctional monomer such as styrene, acrylonitrile, methacrylonitrile, or the like, and further polymerized by adding a polyfunctional monomer. As the rubber-like polymer described above, for example, those described in JP-B-55-27576, JP-A-6-80739, JP-A-49-23292 and the like can be used.

  In a graft copolymer obtained by graft-polymerizing an ethylenically unsaturated monomer at a ratio of 95 to 20 parts by weight to 5 to 80 parts by weight of a rubbery polymer, examples of the rubbery polymer include polybutadiene rubber and acrylonitrile. / Butadiene copolymer rubber, diene rubber such as styrene / butadiene copolymer rubber, acrylic rubber such as polybutyl acrylate, polypropyl acrylate, poly-2-ethylhexyl acrylate, and ethylene / propylene / non-conjugated diene rubber Etc. Examples of the ethylenic monomer include styrene, acrylonitrile, alkyl (meth) acrylate, and the like, and an acrylic unsaturated monomer is preferable. These are used alone or in combination of two or more. Also good. As the above-mentioned graft copolymer, for example, those described in JP-A Nos. 55-147514 and 47-9740 can be used.

  The addition amount of the rubber-like polymer is preferably 0 to 100 parts by weight, and more preferably 3 to 50 parts by weight with respect to 100 parts by weight of the methyl methacrylate resin. If the amount of the rubbery polymer added is too large, the rigidity of the extruded plate is lowered, which is not preferable.

  As an aromatic polycarbonate resin, in addition to those obtained by reacting a dihydric phenol and a carbonate precursor by an interfacial polycondensation method or a melt transesterification method, a product obtained by polymerizing a carbonate prepolymer by a solid phase transesterification method, or Examples thereof include 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 {(4- Droxy-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- -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, Examples include 4′-dihydroxydiphenyl sulfide, 4,4′-dihydroxydiphenyl ketone, 4,4′-dihydroxydiphenyl ether, and 4,4′-dihydroxydiphenyl ester. These may be used alone or in combination of two or more. May be.

  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)- A homopolymer or copolymer obtained from at least one bisphenol selected from the group consisting of 3,3,5-trimethylcyclohexane and α, α′-bis (4-hydroxyphenyl) -m-diisopropylbenzene is preferred. In particular, homopolymers of bisphenol A, and 1,1-bis (4-hydroxyphenyl) -3,3,5-trimethyl At least one selected from rucyclohexane and bisphenol A, 2,2-bis {(4-hydroxy-3-methyl) phenyl} propane, and α, α'-bis (4-hydroxyphenyl) -m-diisopropylbenzene A copolymer with a dihydric phenol is preferred.

  As the carbonate precursor, for example, carbonyl halide, carbonate ester, haloformate or the like is used, and specific examples include phosgene, diphenyl carbonate, dihaloformate of dihydric phenol, and the like.

  The styrene resin is a polymer having a styrene monofunctional monomer unit as a main component, and specifically, a polymer containing 50% by weight or more of a styrene monofunctional monomer unit. The styrene resin may be a homopolymer of a styrene monofunctional monomer, or may be a copolymer of a styrene monofunctional monomer and a monofunctional monomer copolymerizable therewith. Good.

  Examples of the styrene monofunctional monomer include substituted styrene in addition to styrene. Examples of the substituted styrene include halogenated styrenes such as chlorostyrene and bromostyrene, and alkylstyrenes such as vinyltoluene and α-methylstyrene. That is, the styrene monofunctional monomer is a compound having a styrene skeleton and one double bond capable of radical polymerization in the molecule.

  A monofunctional monomer that can be copolymerized with a styrenic monofunctional monomer has one radical-polymerizable double bond in the molecule that can be copolymerized with the styrene monofunctional monomer. Polymerizable compounds, for example, methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2-ethylhexyl methacrylate, 2-hydroxyethyl methacrylate Acrylates such as methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, acrylonitrile, etc. , Methacrylic acid such as methyl methacrylate Ester compounds are preferably used, used alone or in combination of two or more, respectively.

  The styrenic resin may be a resin composition by adding a rubbery polymer. As the rubbery polymer, the same rubbery polymer that can be added to the above-mentioned methyl methacrylate resin can be used. The addition amount of the rubber-like polymer is preferably 0 to 100 parts by weight, more preferably 3 to 50 parts by weight with respect to 100 parts by weight of the styrene resin. If the amount of the rubbery polymer added is too large, the rigidity of the extruded plate is lowered, which is not preferable.

  Examples of the resin containing an alicyclic structure-containing ethylenically unsaturated monomer unit include a norbornene polymer and a vinyl alicyclic hydrocarbon polymer. The resin is characterized by containing an alicyclic structure in the repeating unit of the polymer. The alicyclic structure may be present in either the main chain and / or the side chain, but from the viewpoint of light transmittance, those containing an alicyclic structure in the main chain are preferred.

  Specific examples of the resin containing an alicyclic structure-containing ethylenically unsaturated monomer unit include a norbornene polymer, a monocyclic olefin polymer, a cyclic conjugated diene polymer, and a vinyl alicyclic hydrocarbon system. Examples thereof include polymers and hydrogenated products thereof. Among these, from the viewpoint of light transmittance, a norbornene polymer hydrogenated product, a vinyl alicyclic hydrocarbon polymer or a hydride thereof is preferable, and a norbornene polymer hydrogenated product is more preferable.

  The thermoplastic resin includes, for example, a light diffusing agent, a matting agent, an ultraviolet absorber, a surfactant, an impact resistant agent, a polymer antistatic agent, an antioxidant, a flame retardant, a lubricant, depending on the purpose. Dyes, pigments and the like may be added.

  The thermoplastic resin extruded plate of the present invention comprising the thermoplastic resin described above can be produced by an extrusion molding method. Hereinafter, an embodiment of a method for producing a thermoplastic resin extruded plate according to the present invention will be described in detail with reference to FIGS.

  As shown in FIG. 1, first, the above-described thermoplastic resin is melt-kneaded by an extruder 1 and / or an extruder 2 to obtain a molten thermoplastic resin (hereinafter referred to as “molten thermoplastic resin”) 4. Extrude into a plate shape from the die 3. When making an extrusion board into a laminated structure, it can manufacture by a coextrusion molding method. That is, the thermoplastic resin is melted and kneaded by the extruder 1 and supplied to the die 3, and the other thermoplastic resin is melted and kneaded by the extruder 2 and supplied to the die 3. You just have to.

  Examples of the extruders 1 and 2 include a single screw extruder and a twin screw extruder. The number of extruders is not limited to two, and may be a plurality of three or more. As the die 3, a T die is usually used, and in addition to a single layer die for extruding a thermoplastic resin as a single layer, a feed block die, a multi-manifold die, etc. It is also possible to employ a multilayer die or the like in which two or more kinds of pumped thermoplastic resins are laminated and coextruded.

  The molten thermoplastic resin 4 extruded from the die 3 is molded and cooled by the cooling unit 5. The cooling unit 5 is composed of three cooling rolls arranged to face each other in a substantially horizontal direction. The three cooling rolls include a first cooling roll 6, a second cooling roll 7, and a subsequent cooling roll 8 that are sequentially arranged along the direction of taking the molten thermoplastic resin 4 indicated by an arrow A. These cooling rolls 6 to 8 are configured such that at least one roll is connected to a rotation driving means such as a motor, and each roll rotates at a predetermined peripheral speed.

  The cooling rolls 6 to 8 are not particularly limited, and normal cooling rolls conventionally used in extrusion molding can be employed. Specific examples include a drilled roll, a spiral roll, a metal elastic roll, and a rubber roll. The surface state of the cooling rolls 6 to 8 may be, for example, a mirror surface, or may have a pattern or unevenness.

  As shown in FIG. 2, the molding / cooling by the cooling unit 5 is performed after the molten thermoplastic resin 4 is sandwiched between the first cooling roll 6 and the second cooling roll 7 and wound around the second cooling roll 7. The thermoplastic resin extruded plate 10 is obtained by being wound around a subsequent-stage cooling roll 8 and then taken up by a take-up roll (not shown).

  As shown in FIG. 3, the extruded plate 10 is curved on the other surface 10b opposite to the one surface 10a in contact with the outer peripheral surface 7a of the second cooling roll 7 wound first. Specifically, the extruded plate 10 is curved so that the other surface 10b satisfies the following (i) to (iii).

(I) The center of curvature is located on the other surface 10b side. That is, the extruded plate 10 is curved so as to be concave toward the other surface 10b.
(Ii) The bending direction is an extrusion direction shown in FIG. 3A (hereinafter sometimes referred to as “MD”) and a direction orthogonal to the extrusion direction shown in FIG. TD ”))) in at least one direction.
(Iii) The radius of curvature is 10 to 200 m, preferably 15 to 180 m, more preferably 20 to 150 m.

  That is, the extruded plate 10 is given a specific warp so that the other surface 10b is curved so as to satisfy the above (i) to (iii). Thereby, the curvature deformation of the extrusion board in a high-temperature, high-humidity environment can be suppressed. The reason for this is presumed as follows.

  In the process of molding and cooling the molten thermoplastic resin 4 by the cooling unit 5, generally, internal stress tends to accumulate. When the molten thermoplastic resin 4 is molded and cooled so that the above-described specific warp is imparted to the extruded plate 10, the internal stress is difficult to accumulate, and therefore the obtained extruded plate 10 is warped in a high temperature and high humidity environment. It is inferred that it will be difficult to deform. In particular, in the above (iii), if the radius of curvature is less than 10 m, the warpage applied in advance is too large and adversely affects the assembling process, and if it exceeds 200 m, the effect of suppressing warpage deformation is reduced. The “high temperature and high humidity environment” means an environment having a temperature of 30 ° C. or higher and a humidity of 70% or higher. For example, an environment having a temperature of 60 ° C. or higher and a humidity of 95% or higher, or 80 ° C. An environment that is immersed in warm water of about 1 hour may be used.

  As a method of imparting the warp as described above, a heater is attached below the second cooling roll 7 or above the subsequent cooling roll 8 to heat the molten thermoplastic resin 4, or the surface temperature of the cooling rolls 6 to 8 is adjusted. For example, a method of adjusting to obtain a desired warp can be used. Generally, when the surface temperature of the second cooling roll 7 is lowered, the warpage along the outer peripheral surface of the second cooling roll 7 tends to become strong. Further, when the surface temperature of the rear cooling roll 8 is lowered, the warpage along the outer peripheral surface of the rear cooling roll 8 tends to become stronger.

  On the other hand, when the molten thermoplastic resin 4 is sandwiched between the cooling rolls 6 to 8 and molded, it is necessary to sandwich the molten thermoplastic resin 4 between the rolls before cooling or solidification.

  Specifically, the surface temperature (Tr) of the cooling rolls 6 to 8 is set to (Th−20 ° C.) ≦ Tr ≦ (Th + 20 ° C.) with respect to the thermal deformation temperature (Th) of the thermoplastic resin, preferably (Th −15 ° C.) ≦ Tr ≦ (Th + 10 ° C.), more preferably (Th−10 ° C.) ≦ Tr ≦ (Th + 5 ° C.). When the surface temperature (Tr) is lower than (Th-20 ° C.), the resin is easily peeled off from the roll, and touch errors are likely to occur, which is not preferable. Also, when the surface temperature (Tr) is higher than (Th + 20 ° C.), it is difficult to remove the resin uniformly from the roll, and it is easy to generate a line in the width direction due to an impact at the time of roll peeling called a touch mark. Absent.

  In addition, although it does not specifically limit as heat deformation temperature (Th) of the said thermoplastic resin, Usually, it is about 60-200 degreeC. The heat distortion temperature (Th) of the thermoplastic resin is a temperature measured according to ASTM D-648. In addition, regarding the surface temperature (Tr) when the extruded plate is made into a laminated structure by co-extrusion of two or more different thermoplastic resins, the thermal deformation temperature (Th) is the highest among the two or more different thermoplastic resins. Based on high thermoplastic resin.

  The thickness of the extruded plate 10 is preferably 0.3 to 5 mm, more preferably 0.5 to 3 mm, and still more preferably 0.6 to 2 mm. When the thickness of the extruded plate 10 is too large or thin, it tends to be difficult to control warpage. Note that the obtained extruded plate 10 may be formed with a cured film on its surface or subjected to an antireflection treatment as necessary.

  The thermoplastic resin extruded plate of the present invention thus obtained can be used for various applications because of its small warpage deformation under high temperature and high humidity environment. Among them, it is suitably used as a light guide plate, a touch panel substrate, and a liquid crystal display protective plate. The Applications of such touch panels and liquid crystal displays include, for example, display windows of portable information terminals such as televisions and computer monitors, mobile phones, PHS (Personal Handy-phone System), PDA (Personal Digital Assistant), digital cameras, and handheld types. Examples include a finder portion of a video camera and a display window of a portable game machine.

  In order to produce a light guide plate from the thermoplastic resin extruded plate of the present invention, the extruded plate may be cut to a required size. In order to produce a touch panel substrate or a display protection plate, first, if necessary, processing such as printing and drilling is performed on the extruded plate, and then the extruded plate is cut into a required size. Thereafter, if the extruded plate is set on a display, it can be suitably used as a touch panel substrate or a display protection plate. In that case, it is preferable to set an extrusion board so that the single side | surface which contact | connected the outer peripheral surface of the 2nd cooling roll becomes the front side (viewer side) among the both surfaces.

  As mentioned above, although preferable embodiment concerning this invention was described, this invention is not limited to the above embodiment, A various improvement and change are possible within the range described in the claim. For example, in the above-described embodiment, the number of cooling rolls is three, but may be four or more. That is, the number of the rear cooling rolls is not limited to one, and may be two or more. In the case where a plurality of rear cooling rolls are used, the number is usually about 2-4. Moreover, it is not necessary to unify all the types of cooling rolls to be the same.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further in detail, this invention is not limited to a following example.

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 100 mm, a single screw, and a vent (manufactured by Hitachi Zosen Corporation) was used.
Extruder 2: An extruder with a screw diameter of 35 mm, a single screw, and a vent (manufactured by Hitachi Zosen Corporation) was used.
Feed block: 2 types, 2 layers distribution, 2 types, 3 layers distribution (manufactured by Hitachi Zosen) were used.
Die 3: A T-die (manufactured by Hitachi Zosen Corporation) having a lip width of 1500 mm and a lip interval of 1 mm was used.
Cooling unit 5: Horizontal type, cooling rolls 6-8 having a surface length of 1600 mm and a diameter of 300 mmφ were used. The cooling rolls 6 to 8 are as follows.

1st cooling roll 6: The metal elastic roll mentioned later was used.
Second cooling roll 7: A stainless steel spiral roll having a mirror surface was used.
Subsequent cooling roll 8: The metal elastic roll mentioned later was used.

  The metal elastic roll used in the cooling rolls 6 and 8 was a metal elastic roll in which a metal thin film was disposed so as to cover the outer peripheral surface of the shaft roll, and a fluid was 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 2 mm thick stainless steel mirror metal sleeve was used.
Fluid: Oil was used. In addition, temperature control of this oil was enabled by temperature-controlling this oil. 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.

The thermoplastic resins used in the following examples and comparative examples are as follows.
Resin 1: A polymer containing only aromatic polycarbonate (“Caliver 301-10” manufactured by Sumitomo Dow Co., Ltd.) was used. The heat distortion temperature (Th) is 140 ° C.
Resin 2: A copolymer of methyl methacrylate / methyl acrylate = 98/2 (weight ratio) was used. The heat distortion temperature (Th) is 100 ° C.
Resin 3: 30% by weight of an acrylic multilayer structure polymer (rubber polymer) obtained in the following Reference Example is contained in 70% by weight of a copolymer of methyl methacrylate / methyl acrylate = 96/4 (weight ratio). Acrylic resin-based composition was used. The heat distortion temperature (Th) is 100 ° C.

[Reference example]
(Production of acrylic multilayer polymer)
An acrylic multilayer structure polymer having a three-layer structure was produced in accordance with the method described in the example of JP-B-55-27576. Specifically, first, 1700 g of ion-exchanged water, 0.7 g of sodium carbonate, and 0.3 g of sodium persulfate were charged into a glass reaction vessel having an internal volume of 5 L. Next, after stirring under a nitrogen stream, 4.46 g of PELEX OT-P (manufactured by Kao Corporation), 150 g of ion-exchanged water, 150 g of methyl methacrylate, and 0.3 g of allyl methacrylate were further charged. Thereafter, the temperature was raised to 75 ° C. and stirring was continued for 150 minutes.

  Subsequently, a mixture of 689 g of butyl acrylate, 162 g of styrene, 17 g of allyl methacrylate, 0.85 g of sodium persulfate, 7.4 g of PELEX OT-P and 50 g of ion-exchanged water was added over 90 minutes from another inlet, and polymerization was continued for 90 minutes. Continued.

  After the completion of the polymerization, 30 g of ion-exchanged water in which a mixture of 326 g of methyl acrylate and 14 g of ethyl acrylate and 0.34 g of sodium persulfate were dissolved was added through a separate mouth over 30 minutes.

  After completion of the addition, the polymerization was completed by holding for another 60 minutes to obtain a latex. The obtained latex was put into a 0.5% aluminum chloride aqueous solution to aggregate the polymer. This was washed 5 times with warm water and then dried to obtain an acrylic multilayer structure polymer.

[Examples 1, 3, 4 and Comparative Examples 1, 3]
<Production of thermoplastic resin extrusion plate>
First, the extruders 1 and 2, the die 3, and the cooling rolls 6 to 8 were arranged as shown in FIG. 1, and the feed block was arranged at a predetermined position. Next, as the resin layer A, the types of resins shown in Table 1 were melt-kneaded by the extruder 1 and supplied to the feed block. On the other hand, as the resin layer B, the types of resins shown in Table 1 were melt-kneaded by the extruder 2 and supplied to the feed block. And it coextruded from the die | dye 3 so that the resin layer B supplied to the feed block from the extruder 2 may be laminated | stacked on both surfaces of the resin layer A supplied from the extruder 1 to a feed block.

  The molten thermoplastic resin 4 coextruded from the die 3 is formed and cooled by passing between cooling rolls 6 to 8 having the surface temperature shown in Table 1, and a thermoplastic resin extruded plate having a three-layer structure having the thickness shown in Table 1 Got. Note that the temperatures of the cooling rolls 6 to 8 in Table 1 are values obtained by actually measuring the surface temperatures of the cooling rolls 6 to 8.

  Further, “thickness” in the extruders 1 and 2 in Table 1 indicates the thickness of each of the resin layers A and B. More specifically, the value described in the “thickness” column in the extruder 2 indicates “thickness of one surface layer / thickness of the other surface layer”. “Total thickness” in Table 1 represents the total thickness of the obtained extruded plate.

  Moreover, about Example 1 and Comparative Example 1, the heater was installed under the 2nd cooling roll 7, and the temperature of the heater was made into the temperature shown in Table 1.

[Example 2 and Comparative Example 2]
The resin layer A supplied from the extruder 1 to the feed block is co-extruded from the die 3 so that the resin layer B supplied from the extruder 2 to the feed block is laminated on one side, and the surface of the resin layer B is the second surface. Co-extrusion molding was carried out in the same manner as in Examples 1, 3, and 4 except that it was in contact with the cooling roll 7.

  Then, the molten thermoplastic resin 4 coextruded from the die 3 is molded and cooled by passing between the cooling rolls 6 to 8 having the surface temperature shown in Table 1, and the thermoplastic resin having a two-layer structure having the thickness shown in Table 1 is obtained. An extruded plate was obtained. In addition, the same heater as Example 1 was installed under the 2nd cooling roll 7, and the temperature of the heater was made into the temperature shown in Table 1.

[Example 5 and Comparative Example 4]
Extrusion was carried out in the same manner as in Examples 1, 3 and 4 except that the types of resins shown in Table 1 were melt-kneaded in the extruder 1 and fed in the order of the feed block and the die 3. Then, the molten thermoplastic resin 4 extruded from the die 3 is formed and cooled by passing between the cooling rolls 6 to 8 having the surface temperature shown in Table 1, and the thermoplastic resin extruded with a single layer structure having the thickness shown in Table 1 is used. I got a plate. In addition, about Example 5, the same heater as Example 1 was installed under the 2nd cooling roll 7, and the temperature of the heater was made into the temperature shown in Table 1.

<Evaluation>
About each obtained extrusion board (Examples 1-5 and Comparative Examples 1-4), the amount of curvature, a curving direction, a curvature radius, warm water immersion curvature amount, and the amount of movement were evaluated. Each evaluation method is shown below, and the results are shown in Table 1.

(Warping amount, bending direction, radius of curvature)
First, three test pieces were cut out from the obtained extruded plate along a direction (TD) orthogonal to the extrusion direction (MD). The shape of each test piece was set to 400 mm for MD and 275 mm for TD.

  Next, each test piece was placed on a surface plate, and the amount of lifting of the four corners of each test piece was measured using a gap gauge. And the average value of all the lifts in each test piece was calculated, and this was made into the amount of curvature. At this time, if the surface on which the angle to be measured is lifted is “+” if the other surface opposite to the one surface in contact with the outer peripheral surface of the second cooling roll 7 is “+”, it is the one surface in contact with the outer peripheral surface of the second cooling roll 7. If there was, it was evaluated as “−”.

  Furthermore, the curvature radius was calculated from the obtained amount of warpage and the length of the test piece in the direction in which the test piece is curved. When the bending direction is MD, the test piece length is 400 mm, and when the bending direction is TD, the test piece length is 275 mm.

(Warm water immersion warpage and travel)
First, the three test pieces used for measuring the amount of warpage were immersed in warm water at 80 ° C. for 1 hour, and then immersed in cold water for 1 minute to cool. Next, each test piece was placed on a surface plate, and the amount of lifting of the four corners of each test piece was measured using a gap gauge.

  And the average value of all the floating amount in each test piece was computed, and this was made into warm water immersion curvature amount. At this time, like the warp amount, if the surface on which the angle to be measured is lifted is the other surface opposite to the one surface in contact with the outer peripheral surface of the second cooling roll 7, “+”, the outer periphery of the second cooling roll 7 If it was one side in contact with the surface, it was evaluated as “−”.

Furthermore, the movement amount was calculated from the formula: (warm water immersion warpage amount) − (warpage amount). In Comparative Examples 1, 2, and 4, the four surfaces of the test piece that floated up changed before and after immersion in hot water as follows.
Before soaking in warm water: After soaking one side of warm water in contact with the outer peripheral surface of the second cooling roll 7: On the other side opposite to one side For Comparative Examples 1, 2 and 4, the formula: (warming amount of warm water soaking) + (warping amount) ) To calculate the amount of movement.

  As is clear from Table 1, Examples 1 to 5 showed results in which the value of the warm water immersion warpage amount was small and the value of the movement amount was also small. From this result, it can be seen that Examples 1 to 5 are unlikely to warp and deform under a high temperature and high humidity environment. On the other hand, the one side which contacted the outer peripheral surface of the 2nd cooling roll 7 is curving, the comparative examples 1 and 2 in which the curvature center is located in the single side, the curvature radius exceeds 200m, In the comparative example 4 in which the one side is curved, the center of curvature is located on one side, and the radius of curvature exceeds 200 m, the value of the warm water immersion warpage amount is large and the value of the movement amount is also Great results were shown.

DESCRIPTION OF SYMBOLS 1, 2 Extruder 3 Die 4 Molten thermoplastic resin 5 Cooling unit 6 1st cooling roll 7 2nd cooling roll 7a Outer peripheral surface 8 Subsequent cooling roll 10 Thermoplastic resin extrusion board 10a Single side 10b Other side

Claims (5)

A molten thermoplastic resin extruded from a die is sandwiched between a first cooling roll and a second cooling roll, wound around the second cooling roll, and then wound around at least one subsequent cooling roll. A thermoplastic resin extrusion plate,
The other surface opposite to the one surface in contact with the outer peripheral surface of the second cooling roll is curved,
The center of curvature is located on the other side,
The bending direction is at least one of an extrusion direction and a direction orthogonal to the extrusion direction;
A thermoplastic resin extruded plate for a touch panel substrate , wherein a curvature radius is 10 to 200 m. A molten thermoplastic resin extruded from a die is sandwiched between a first cooling roll and a second cooling roll, wound around the second cooling roll, and then wound around at least one subsequent cooling roll. A thermoplastic resin extrusion plate,
The other surface opposite to the one surface in contact with the outer peripheral surface of the second cooling roll is curved,
The center of curvature is located on the other side,
The bending direction is at least one of an extrusion direction and a direction orthogonal to the extrusion direction;
A thermoplastic resin extruded plate for a liquid crystal display protective plate, wherein the curvature radius is 10 to 200 m. Wherein the thermoplastic resin is a methyl methacrylate-based resin, an aromatic polycarbonate resin, styrene resin, and is at least one selected from alicyclic structure-containing ethylenically unsaturated resin containing a monomer unit according to claim 1 or 2. The thermoplastic resin extruded plate according to 2. The thermoplastic resin is a laminate of at least two thermoplastic resins,
Each thermoplastic resin to be laminated is at least one selected from a methyl methacrylate resin, an aromatic polycarbonate resin, a styrene resin, and a resin containing an alicyclic structure-containing ethylenically unsaturated monomer unit. The thermoplastic resin extrusion board in any one of Claims 1-3. The thermoplastic resin extruded plate according to any one of claims 1 to 4 , which has a thickness of 0.3 to 5 mm.

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