JP2009154442A - Manufacturing method of extruded resin plate for optical member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of an extruded resin plate for an optical member further lowered in retardation in the thickness direction. <P>SOLUTION: The manufacturing method of the extruded resin plate for the optical member is provided by which thermoplastic resin is extruded from a die in a heated and molten state, sandwiched between first and second cooling rolls, wound around the second cooling roll, then sequentially wound around one or more pieces of rear stage cooling rolls to be cooled, further cooled for solidifying keeping it flat, and taken off by a pair of take-off rolls, to manufacture the extruded resin plate for the optical member. An average circumferential speed of the rear stage cooling rolls is 0.94-1.03 times of an average circumferential speed of the first and second cooling rolls, an average circumferential speed of the pair of the take-off rolls is 0.95-1.03 times of the average circumferential speed of the rear stage cooling rolls, and the average circumferential speed of the pair of the take-off rolls is not lower than 0.91 times and lower than 0.95 times of the average circumferential speed of the first and second cooling rolls. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing an extruded resin plate for an optical member, and more specifically, a method for producing an extruded resin plate for an optical member by extruding a thermoplastic resin from a die in a heated and melted state and cooling it by winding it on a cooling roll. About.

  It is known that an extruded resin plate produced by extruding a thermoplastic resin from a die in a heated and melted state is used for various applications. For example, a Fresnel lens, which is a screen material for a projection television, or a polarizing plate. It is known to be used for so-called optical members such as a resin plate for protecting the film. As such an extruded resin plate for an optical member, one having a low retardation (phase difference) in the thickness direction is desired.

On the other hand, as a method for producing an extruded resin plate by extruding a thermoplastic resin from a die in a heat-melted state, Japanese Patent Application Laid-Open No. 2007-185958 (Patent Document 1) extrudes a thermoplastic resin from a die in a heat-melted state, It is sandwiched between one cooling roll and the second cooling roll, wound around the second cooling roll, and then wound around one subsequent cooling roll or sequentially wound around a plurality of subsequent cooling rolls. Then, while maintaining a flat state, it is further cooled and solidified, and is taken up by a pair of take-up rolls to produce an extruded resin plate,
(1) The peripheral speed of the one subsequent cooling roll or the average peripheral speed of the plurality of subsequent cooling rolls is 0.94 times to 1 with respect to the average peripheral speed of the first cooling roll and the second cooling roll. .03 times,
(2) The average peripheral speed of the pair of take-up rolls is 0.95 to 1.03 times the peripheral speed of the one subsequent cooling roll or the average peripheral speed of the plurality of subsequent cooling rolls. ,
(3) An extruded resin plate, wherein an average peripheral speed of the pair of take-up rolls is 0.95 to 0.995 times an average peripheral speed of the first cooling roll and the second cooling roll. The manufacturing method of this is proposed.

JP 2007-185756 A

  However, the extruded resin plate obtained by the method described in the above document has a high retardation in the thickness direction, and is not satisfactory for optical members.

  Accordingly, an object of the present invention is to provide a method capable of producing an extruded resin plate having lower retardation in the thickness direction and suitable for optical members.

  Under such circumstances, the present inventors have intensively studied to achieve the above object, and as a result have completed the present invention.

That is, the present invention extrudes a thermoplastic resin from a die in a heated and melted state,
Sandwiched between the first cooling roll and the second cooling roll,
After winding around the second cooling roll,
Cool by winding on one subsequent cooling roll, or by winding sequentially on multiple subsequent cooling rolls,
Then, while maintaining a flat state, it is further cooled and solidified,
Take it up by a pair of take-up rolls,
A method for producing an extruded resin plate for an optical member,
(1) The peripheral speed of the one subsequent cooling roll or the average peripheral speed of the plurality of subsequent cooling rolls is 0.94 times to 1 with respect to the average peripheral speed of the first cooling roll and the second cooling roll. .03 times,
(2) The average peripheral speed of the pair of take-up rolls is 0.95 to 1.03 times the peripheral speed of the one subsequent cooling roll or the average peripheral speed of the plurality of subsequent cooling rolls. ,
(3) The optical device characterized in that the average peripheral speed of the pair of take-up rolls is 0.91 times or more and less than 0.95 times the average peripheral speed of the first cooling roll and the second cooling roll. The manufacturing method of the extrusion resin board for members is provided.

  According to the present invention, an extruded resin plate suitable for optical members can be produced with a lower retardation in the thickness direction.

  Hereinafter, the present invention will be described in detail. The thermoplastic resin used in the production method of the present invention may be a general-purpose thermoplastic resin or an engineering plastic such as methacrylic resin, styrene resin, methyl methacrylate-styrene resin, methacrylic acid. Methyl-butadiene-styrene resin, polyvinyl chloride resin, polyethylene resin such as low density polyethylene, high density polyethylene, linear low density polyethylene, polypropylene resin, acrylonitrile-butadiene-styrene resin, acrylonitrile-styrene resin, cellulose acetate resin, Ethylene-vinyl acetate resin, acrylic-chlorinated polyethylene resin, ethylene vinyl alcohol resin, fluorine resin, polyacetal resin, polyamide resin, polyethylene terephthalate resin, polybutylene terf Rate resin, aromatic polycarbonate resin, polysulfone resin, polyethersulfone resin, methylpentene resin, polyarylate resin, resin containing alicyclic structure-containing ethylenically unsaturated monomer unit, polyphenylene sulfide resin, polyphenylene oxide resin, poly Examples include ether ether ketone resins.

  Further, it may be a thermoplastic elastomer, for example, polyvinyl chloride elastomer, chlorinated polyethylene, ethylene-ethyl acrylate resin, thermoplastic polyurethane elastomer, thermoplastic polyester elastomer, ionomer resin, styrene / butadiene block polymer, ethylene- Also included are propylene rubber, polybutadiene resin, acrylic elastomer and the like.

  Among them, as a thermoplastic resin, a methacrylic resin, a styrene resin, a methyl methacrylate-styrene resin, a methyl methacrylate-butadiene-styrene resin, an aromatic polycarbonate resin, A resin containing an alicyclic structure-containing ethylenically unsaturated monomer unit is preferably used.

  As the methacrylic resin, for example, those having a methyl methacrylate unit as a main component, specifically, a methyl methacrylate resin containing usually 50% by mass or more and preferably 70% by mass or more of a methyl methacrylate unit are preferably used. Examples of the methyl methacrylate resin include a methyl methacrylate homopolymer having a methyl methacrylate unit of 100% by mass, and a copolymer with methyl methacrylate and other monomers copolymerizable therewith. .

  Other monomers that can be copolymerized with methyl methacrylate include methacrylic acid esters other than methyl methacrylate, and specific examples thereof include ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, and phenyl methacrylate. , Benzyl methacrylate, 2-ethylhexyl methacrylate, 2-hydroxyethyl methacrylate and the like.

  Examples of other monomers include acrylate esters, and specific examples thereof include methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, and acrylic acid. Examples also include 2-ethylhexyl and 2-hydroxyethyl acrylate.

  Further, other monomers include unsaturated acids such as methacrylic acid and acrylic acid, unsubstituted styrene, halogenated styrenes such as chlorostyrene and bromostyrene, and alkylstyrenes such as vinyltoluene and α-methylstyrene. Substituted styrenes such as acrylonitrile, acrylonitrile, methacrylonitrile, maleic anhydride, phenylmaleimide, cyclohexylmaleimide and the like.

  These other monomers copolymerizable with methyl methacrylate may be used alone or in combination of two or more.

  The styrenic resin is a resin having a styrene monofunctional monomer unit as a main component, for example, a resin containing 50% by mass or more of a styrene monomer unit, and the styrene monofunctional monomer unit is 100% by mass. It may be a styrenic monofunctional monomer and a copolymer of a monofunctional monomer copolymerizable therewith.

  Examples of styrenic monofunctional monomers include unsubstituted styrene, halogenated styrenes such as chlorostyrene and bromostyrene, and substituted styrenes such as vinyltoluene and alkylstyrenes such as α-methylstyrene. Examples thereof include compounds having a skeleton and having one radical bond capable of radical polymerization in the molecule. Styrenic monofunctional monomers may be used alone or in combination of two or more.

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 Kind,
Examples thereof include acrylates such as methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, acrylonitrile, and the like. Methacrylic acid esters, more preferably methyl methacrylate. Such monofunctional monomers are used alone or in combination of two or more.

  The methyl methacrylate-styrene copolymer resin is a copolymer having methyl methacrylate and styrene as essential monomers, and the monomer composition overlaps with the above methyl methacrylate resin and styrene resin. It is possible. The monomer composition is preferably 15 to 85% by mass of methyl methacrylate, 15 to 85% by mass of styrene, and 0 to 30% by mass of other monomers. As monomers other than methyl methacrylate and styrene, the monomers described above can be used.

  Examples of the aromatic polycarbonate resin include those obtained by polymerizing a dihydric phenol and a carbonylating agent by an interfacial polycondensation method or a melt transesterification method, or by polymerizing a carbonate prepolymer by a solid phase transesterification method. And those obtained by polymerizing by a ring-opening polymerization method of a cyclic carbonate compound.

  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, and two or more of them may be used as necessary. it can.

  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) −3,3,5-trimethylcyclohexane and α, α′-bis (4-hydroxyphenyl) -m-diisopropylbenzene are preferred. In particular, bisphenol A alone or 1,1-bis (4-hydroxyphenyl)- 3,3,5-trimethylcyclohexane and bisphenol A, 2,2-bis {(4-hydroxy-3-methyl) phenyl} propa And at least one selected from α, α'-bis (4-hydroxyphenyl) -m-diisopropylbenzene are preferred.

  Examples of the carbonylating agent include carbonyl halides such as phosgene, carbonate esters such as diphenyl carbonate, and haloformates such as dihaloformate.

  The resin containing an alicyclic structure-containing ethylenically unsaturated monomer unit is a resin containing an alicyclic structure in a repeating unit of a polymer, such as a norbornene polymer, a vinyl alicyclic hydrocarbon type A polymer etc. are mentioned.

  The alicyclic structure may be contained in the main chain, may be contained in the side chain, or may be contained in both the main chain and the side chain. The thing containing an alicyclic structure in a principal chain is preferable at the point from which the extruded resin board excellent in the light transmittance is obtained.

  Specific examples of the polymer resin containing such an alicyclic structure include a norbornene polymer, a monocyclic olefin polymer, a cyclic conjugated diene polymer, a vinyl alicyclic hydrocarbon polymer, and these Examples thereof include hydrogenated products. Among these, from the viewpoint of light transmittance, a norbornene-based polymer hydrogenated product, a vinyl alicyclic hydrocarbon-based polymer, a hydride thereof, and the like are preferable, and a norbornene-based polymer hydrogenated product is more preferable.

  Further, the thermoplastic resin may contain a rubber-like polymer. In this case, the rubber-like polymer usually has a refractive index substantially equal to that of the portion other than the rubber-like polymer of the thermoplastic resin. (With a refractive index difference of 0.005 or less) is used.

  When the portion other than the rubber-like polymer of the thermoplastic resin is a methacrylic resin, acrylic rubber particles are suitable as the rubber-like polymer. The acrylic rubber particle is a particle containing an elastic polymer mainly composed of an acrylate ester as a rubber component, and may be a particle having a single layer structure made of only this elastic polymer, or a layer of this elastic polymer. It may be a multi-layered particle having The elastic polymer may be a homopolymer of an acrylate ester or a copolymer of 50% by mass or more of an acrylate ester and 50% by mass or less of other monomers. .

  In addition, when the portion other than the rubber-like polymer of the thermoplastic resin is a methyl methacrylate-styrene copolymer resin, as the rubber-like polymer, a diene rubber copolymer is suitable, and in this case, the diene-based polymer A resin containing a rubbery copolymer is a so-called methyl methacrylate-butadiene-styrene resin. Examples of the diene monomer include butadiene, 2-methylbutadiene, 2,3-dimethylbutadiene, and the like, and two or more of them can be used as necessary. Of these, butadiene is preferred. As the diene rubbery copolymer, styrene-butadiene copolymer rubber is most commonly mentioned. The diene rubbery copolymer may be a random copolymer or a block copolymer. Further, a monomer component other than the rubber-like polymer of the thermoplastic resin may be graft polymerized.

  The thermoplastic resin can be produced, for example, by a bulk polymerization method, a suspension polymerization method, a micro suspension polymerization method, an emulsion polymerization method, a dispersion polymerization method, or the like.

  The thermoplastic resin may contain a light diffusing agent, an ultraviolet absorber, a surfactant, an impact resistance agent, a polymer antistatic agent, an antioxidant, a flame retardant, a lubricant, a colorant such as a dye or pigment, and the like. Good.

  Examples of the light diffusing agent include inorganic particles such as calcium carbonate particles, barium sulfate particles, titanium oxide particles, aluminum hydroxide particles, silica particles, glass particles, talc particles, mica particles, white carbon particles, magnesium oxide particles, and zinc oxide particles. Particles and those obtained by subjecting these inorganic particles to a surface treatment with fatty acid or the like can be mentioned. Moreover, resin particles such as crosslinked styrene resin particles, high molecular weight styrene resin particles, crosslinked acrylic resin particles, high molecular weight acrylic resin particles, crosslinked siloxane resin particles, and high molecular weight siloxane resin particles are also included.

  Next, a series of operations for producing an extruded resin plate by extruding a thermoplastic resin from a die in a heated and melted state will be described with reference to FIGS. 1 and 2 are schematic views showing an example of a method for producing an extruded resin plate by extruding a thermoplastic resin from a die in a heated and melted state, but the present invention is not limited to these.

  As shown in FIG. 1 and FIG. 2, in order to extrude the thermoplastic resin (P0) from the die (1) in a heated and melted state, the thermoplastic resin ( P0) may be heated and pumped to the die (1) while melt kneading. The thermoplastic resin (P0) pumped from the extruder (2) becomes a plate shape while being heated and melted and is extruded from the die (1).

  A T-die is usually used as the die (1). The die (1) may be a single-layer die that extrudes one kind of thermoplastic resin as a single layer, or is independently pumped from the extruder (2), such as a feed block die or a multi-manifold die. It may be a multilayer die in which two or more kinds of thermoplastic resins (P0) are laminated and coextruded.

  The thermoplastic resin (P1) extruded from the die (1) is sandwiched between the first cooling roll (R1) and the second cooling roll (R2).

  As the first cooling roll (R1) and the second cooling roll (R2), those having a diameter almost equal to each other are usually used, and the diameter is usually 25 cm to 100 cm. The first cooling roll (R1) and the second cooling roll (R2) are usually made of a metal material such as stainless steel, and have a mirror finish. The temperature of the first cooling roll (R1) and the second cooling roll (R2) is adjusted so that the thermoplastic resin (P1) extruded from the die (1) is cooled to a predetermined temperature.

  The first cooling roll (R1) and the second cooling roll (R2) have the same peripheral speed, for example, the peripheral speed (V2) of the second cooling roll (R2), for example, by an electric motor (not shown). It is rotationally driven to rotate so as to be in the range of 0.98 times to 1.02 times the peripheral speed (V1) of one cooling roll (R1).

  The thermoplastic resin (P2) after being sandwiched between the first cooling roll (R1) and the second cooling roll (R2) is usually in contact with the second cooling roll (R2). It is wound around a roll (R2).

  The thermoplastic resin (P2) wound around the second cooling roll (R2) is wound around one rear cooling roll (R3) or a plurality of rear cooling rolls (R3, R4,...・ Sequentially wound around.

  As the latter-stage cooling rolls (R3, R4...), Those having a diameter substantially equal to that of the first cooling roll (R1) and the second cooling roll (R2) or those having a smaller diameter can be used. Further, as the rear-stage cooling rolls (R3, R4,...), Those whose surfaces are made of a metal material such as stainless steel and are mirror-finished are usually used. The rear cooling rolls (R3, R4...) Are temperature-controlled so as to cool the thermoplastic resin (P0) extruded from the die (1) to a predetermined temperature.

  The number of the rear-stage cooling rolls (R3, R4...) Is one or more, and is usually about one to four. Preferably there are multiple.

  FIG. 1 shows an example in which one rear cooling roll is used alone. In this example, the thermoplastic resin (P2) wound around the second cooling roll (R2) is usually sandwiched between the second cooling roll (R2) and the subsequent cooling roll (R3). And it winds in the state closely_contact | adhered to this back | latter stage cooling roll (R3).

  One rear cooling roll (R3) is driven to rotate by, for example, an electric motor (not shown), and its peripheral speed (V3) is an average of the first cooling roll (R1) and the second cooling roll (R2). 0.94 times to 1.03 times, preferably 0.95 times to 1.0 times, and more preferably 0.995 times or less with respect to the peripheral speed (V12). If it is less than 0.94 times, the thermoplastic resin (P2) wound around the second cooling roll (R2) becomes difficult to peel off from the roll (R2), and the thermoplastic resin plate (A) is stably removed. When it becomes difficult to manufacture and exceeds 1.03 times, the obtained extruded resin plate (A) has a large retardation.

  FIG. 2 shows an example in which a plurality of rear-stage cooling rolls are used, and more specifically, an example in which three rear-stage cooling rolls (R3, R4, R5) are used.

  The thermoplastic resin (P2) wound around the second cooling roll (R2) is usually sandwiched between the second cooling roll (R2) and the first roll (R3) of a plurality of subsequent cooling rolls. After that, it is wound around this first roll (R2), and is then sandwiched and wound between the subsequent subsequent cooling rolls (R4...) Sequentially.

  Each of the plurality of rear cooling rolls (R3, R4,...) Is rotationally driven by, for example, an electric motor (not shown), and the average peripheral speed (V3a) thereof is the first cooling roll (R1). ) And the average peripheral speed (V12) of the second cooling roll (R2), 0.94 times to 1.03 times, preferably 0.95 times to 1.0 times, and more preferably 0.995 times or less. To do. If it is less than 0.94 times, the thermoplastic resin (P2) wound around the second cooling roll (R2) becomes difficult to peel off from this roll (R2), and the thermoplastic resin plate (A) is stably removed. When it becomes difficult to manufacture and exceeds 1.03 times, the obtained extruded resin plate (A) has a large retardation.

  Thus, after being wound on one subsequent cooling roll (R3) (FIG. 1) or sequentially wound on a plurality of subsequent cooling rolls (R3, R4...) (FIG. 2), The thermoplastic resin (Pr) is then further cooled and solidified while maintaining a flat state. In order to further cool and solidify the thermoplastic resin (Pr) while keeping it in a flat state, for example, on a roller table (Tr) composed of a plurality of transport rollers (Rt), for example, in the same manner as in the ordinary extrusion molding method. What is necessary is just to cool by conveying in air | atmosphere. Such cooling is preferably performed in an atmosphere of 35 ° C. or higher, and is usually 65 ° C. or lower, preferably 60 ° C. or lower, and more preferably in view of shortening the moving distance until the thermoplastic resin (Pr) is solidified. Is 50 ° C. or lower, particularly preferably 45 ° C. or lower.

  As shown in FIGS. 1 and 2, the thermoplastic resin (Pt) after solidification is taken up by a pair of take-up rolls (N1, N2). As the pair of take-up rolls (N1, N2), those having substantially the same diameter are usually used, and the diameter is usually about 15 cm to 80 cm. As the pair of take-up rolls (N1, N2), those whose surfaces are made of a metal material such as stainless steel and mirror-finished, those whose surfaces are made of rubber, and the like are used. Further, the take-up rolls (N1, N2) are driven by an electric motor (not shown) or the like so that the circumferential speed of one take-up roll (N1) is substantially the same as that of the other take-up roll (N2). Is driven so as to be in the range of 0.98 times to 1.02 times the value. The solidified thermoplastic resin (Pt) is sandwiched between the take-up rolls (N1, N2) and taken up.

  In the manufacturing method of the present invention, when only one rear cooling roll (R3) is used as shown in FIG. 1, the average peripheral speed (Vn) of the pair of take-up rolls (N1, N2) is set to this one. 0.95 times to 1.03 times, preferably 0.96 times to 1.01 times, and more preferably 0.965 to 1.00 times with respect to the peripheral speed (V3) of the rear cooling roll (R3). To do. Further, as shown in FIG. 2, when a plurality of rear cooling rolls (R3, R4...) Are used, the average peripheral speed (Vn) of the pair of take-up rolls (N1, N2) is set to a plurality of rear cooling. 0.95 times to 1.03 times, preferably 0.96 times to 1.01 times, more preferably 0.965 to 1 with respect to the average peripheral speed (V3a) of the rolls (R3, R4...) .00 times. If it is less than 0.95 times, the thermoplastic resin (Pr) immediately after being cooled by one or a plurality of subsequent cooling rolls (R3, R4...) Is likely to meander and be kept flat. It becomes difficult. Moreover, when it exceeds 1.03 times, the extrusion resin board (A) obtained will have a large retardation.

  In the manufacturing method of the present invention, the average peripheral speed (Vn) of the pair of take-up rolls (N1, N2) is set to the average peripheral speed (V12) of the first cooling roll (R1) and the second cooling roll (R2). 0.91 times or more and less than 0.95 times, preferably 0.93 times or more and less than 0.95 times. If it is less than 0.91, the thermoplastic resin (Pr) immediately after being cooled by one or a plurality of subsequent cooling rolls (R3, R4...) Is likely to meander and maintain a flat state. It becomes difficult. If it is 0.95 times or more, the resulting extruded resin plate (A) has a large retardation.

  The extruded resin plate (A) after being taken up by the take-up rolls (N1, N2) is usually cut into an appropriate length.

  The production method of the present invention is suitable for producing an extruded resin plate (A) having a thickness of 0.05 to 8 mm, and more suitable for producing an extruded resin plate (A) having a thickness of 0.5 mm to 5 mm. It is. The thickness of the extruded resin plate (A) obtained is determined by, for example, the thickness of the thermoplastic resin (P1) extruded from the die (1), the interval between the first cooling roll (R1) and the second cooling roll (R2), etc. It can be adjusted by adjusting.

  Thus, a desired extruded resin plate (A) can be obtained. Such an extruded resin plate has a low retardation in the thickness direction and is suitable as an extruded resin plate for an optical member. The production method of the present invention is preferable for producing an extruded resin plate having a thickness direction retardation of 180 nm or less, and more preferably for producing an extruded resin plate having a retardation of 160 nm or less.

  The optical member here can be a member of a display device using liquid crystal as an image source, for example, a Fresnel lens that is a screen material of a projection television, a resin plate for protecting a polarizing plate, and the like. It is done. In particular, when an extruded resin plate is used as a Fresnel lens substrate, one side of the extruded resin plate is formed into a Fresnel lens shape, and passes through a polarizing plate and a liquid crystal panel on the surface opposite to the surface subjected to the Fresnel lens shape. In this case, if the extruded resin plate has a retardation in the thickness direction of more than 180 nm, the degree of coloring of the projected image increases. Therefore, an extruded resin plate having a retardation in the thickness direction of 180 nm or less is suitable as the extruded resin plate for Fresnel lenses. In this respect, the production method of the present invention produces an extruded resin plate for Fresnel lenses. It is suitable as a method.

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

  In addition, the evaluation method in an Example is as follows.

(1) Retardation (unit: nm)
Using an automatic birefringence meter (KOBRA-WR0 manufactured by Oji Scientific Instruments Co., Ltd.), the retardation in the thickness direction of the extruded resin plate was measured at a measurement wavelength of 590 nm.

(2) Degree of coloring when an extruded resin plate is used as a Fresnel lens substrate In the extruded resin plates obtained by Examples and Comparative Examples described later, the surface opposite to the surface layer is made of a cured product of an ultraviolet curable resin. A Fresnel lens was molded to obtain a Fresnel lens sheet. A surface layer of the obtained Fresnel lens sheet is used as a light incident surface of light from a light source, and a lenticular lens sheet having black stripes with a pitch of 0.15 mm is superimposed on the observation surface side of the Fresnel lens sheet. Set in a thin rear projection television with a liquid crystal light source. In this state, a white screen was output and the degree of coloring of the screen was observed. As the evaluation of the degree of coloring, ◎ (the degree of coloring is very small), ○ (the degree of coloring is small), Δ (the degree of coloring is large) × (the degree of coloring is very large).

Example 1
The first extruder (screw diameter 130 mm, uniaxial, with vent) was charged with 99.7 parts by mass of thermoplastic resin (a) and 0.3 part by mass of fine particles (b), and the second extruder (slew diameter 65 mm, Uniaxial, vented) was charged with 78 parts by weight of thermoplastic resin (a) and 22 parts by weight of fine particles (b). Next, a two-type two-layer distribution type multi-manifold die is disposed at the tip of the extruder, and the layer extruded from the first extruder is used as the main layer in the die maintained at about 250 ° C. The two layers having the surface extruded from the surface as the surface layer were integrated so that the surface layer surface was the lower surface (second cooling roll side). The thermoplastic resin (a) and fine particles (b) having the following composition were used.

(A) Copolymer of 20 parts by weight of methyl methacrylate and 80 parts by weight of styrene [refractive index 1.57, heat distortion temperature 97 ° C.]
(B) Copolymer particles comprising 32 parts by mass of methyl methacrylate, 63 parts by mass of styrene, and 5 parts by mass of divinylbenzene [weight average particle diameter 8 μm, refractive index 1.56]

  Next, as shown in FIG. 2, the thermoplastic resin (P1) extruded from the T-die (1) has the first cooling roll (R1) and the second cooling roll so that the surface layer is on the second cooling roll side. Between the second cooling roll (R2) and the third cooling roll (R3; the first of the second-stage cooling rolls) while sandwiched between the cooling roll (R2) and tightly wound around the second cooling roll (R2) The second cooling roll is sandwiched between the third cooling roll (R3) and the fourth cooling roll (R4; the second cooling roll) while being in close contact with and wound around the third cooling roll (R3). While being in close contact with the roll (R4), the roll is sandwiched between the fourth cooling roll (R4) and the fifth cooling roll (R5; the third cooling roll), and is wound on the fifth cooling roll (R5). And cooled. At this time, the first cooling roll (R1), the second cooling roll (R2), the third cooling roll (R3), and the fourth cooling roll (R4) have a stainless steel diameter of 50 cm and the surface thereof is mirror-like. A plated finish was used, and the fifth cooling roll (R5) was made of stainless steel having a diameter of 22 cm and the surface of which was mirror-finished. Thereafter, the thermoplastic resin (Pr) is allowed to cool and solidify while being conveyed on a roller table (Tr) composed of 25 conveying rolls (Rt) while maintaining a flat state, and a pair of take-up rolls (N1) , N2) to obtain an extruded resin plate (A) having a thickness of 2.50 mm and a width of 125 cm. The take-up rolls (N1, N2) were 30 cm in diameter and made of rubber.

Examples 2 to 5 and Comparative Examples 1 to 2
The same operation as in Example 1 was performed except that the peripheral speed of each roll and the thickness of the resin plate were as shown in Table 1. The results are shown in Table 1.

It is a schematic diagram showing an example of a method for producing an extruded resin plate by extruding a thermoplastic resin from a die in a heated and melted state. It is a schematic diagram which shows another example of the method of extruding a thermoplastic resin from a die | dye in a heat-melting state, and manufacturing an extruded resin board.

Explanation of symbols

1: Die 2: Extruders P0, P1, P2, P3, P4, Pr, Pt: Thermoplastic resin R1: First cooling roll R2: Second cooling roll R3: Third cooling roll R4: Fourth cooling roll R5: Fifth cooling roll Rt: transport roll Tr: roller table N1, N2: take-up roll

Claims (3)

Extrude the thermoplastic resin from the die in a heated and melted state,
Sandwiched between the first cooling roll and the second cooling roll,
After winding around the second cooling roll,
Cool by winding on one subsequent cooling roll, or by winding sequentially on multiple subsequent cooling rolls,
Then, while maintaining a flat state, it is further cooled and solidified,
Take it up by a pair of take-up rolls,
A method for producing an extruded resin plate for an optical member,
(1) The peripheral speed of the one subsequent cooling roll or the average peripheral speed of the plurality of subsequent cooling rolls is 0.94 times to 1 with respect to the average peripheral speed of the first cooling roll and the second cooling roll. .03 times,
(2) The average peripheral speed of the pair of take-up rolls is 0.95 to 1.03 times the peripheral speed of the one subsequent cooling roll or the average peripheral speed of the plurality of subsequent cooling rolls. ,
(3) The optical device characterized in that the average peripheral speed of the pair of take-up rolls is 0.91 times or more and less than 0.95 times the average peripheral speed of the first cooling roll and the second cooling roll. A method for producing an extruded resin plate for members.   The manufacturing method according to claim 1, wherein there are a plurality of the subsequent cooling rolls.   The manufacturing method of Claim 1 or 2 which manufactures the extruded resin board for Fresnel lenses as an extruded resin board for optical members.

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