JP7160838B2 - Method for manufacturing liquid crystal display protection plate - Google Patents

Description

The present invention relates to a method for manufacturing a liquid crystal display protective plate.

A liquid crystal display and a touch panel display in which a liquid crystal display and a touch panel are combined are sometimes provided with a protective plate on the front side thereof in order to prevent the surface from being scratched or the like. In this specification, this protective plate is called a "liquid crystal display protective plate".
As a liquid crystal display protective plate, a cured film having scratch resistance (hard coat property) and / or low reflectivity for improving visibility and suppressing glare on the surface of a resin plate consisting of at least one layer of thermoplastic resin layer anti-glare film, anti-fouling film that suppresses adhesion of dirt, anti-static film that suppresses adhesion of dust, and a transparent conductive film that imparts the necessary conductivity to the touch panel. are being considered for use.
For example, Patent Document 1 discloses a scratch-resistant resin plate that includes a methacrylic resin plate and a cured coating formed on at least one surface thereof, and is suitable as a display window protection plate for a portable information terminal. (Claim 1, 2, 7, etc.). Patent Document 2 discloses a polycarbonate resin laminate for a liquid crystal display cover, which includes a laminate obtained by laminating a methacrylic resin layer on one side of a polycarbonate resin layer, and a cured film formed on the methacrylic resin layer of the laminate. It is disclosed (claim 1).

Examples of methods for manufacturing the resin plate include injection molding and extrusion molding.
As a method for forming the functional layer, a method of applying a liquid curable composition containing a thermosetting compound or an active energy ray-curable compound and curing the coating film by heating or irradiating with an active energy ray (Patent Document 1, 2); A method of applying a liquid obtained by dispersing or dissolving a functional material or a precursor of a functional material in water, an organic solvent, etc., and drying or heating; A PET (polyethylene terephthalate) film having a functional layer formed in advance on its surface. A method of laminating a resin film such as using an adhesive or a pressure-sensitive adhesive.
A drying process or a heating process for adjusting the warp state, etc., and a thermoforming process for performing shape processing such as curved surface processing on the resin plate before forming the functional layer or the resin plate after forming the functional layer. etc. may be implemented.

The liquid crystal display protection plate is installed on the front side (viewer side) of the liquid crystal display, and the viewer sees the screen of the liquid crystal display through this protection plate. Here, since the liquid crystal display protective plate hardly changes the polarization of the light emitted from the liquid crystal display, when the screen is viewed through a polarizing filter such as polarized sunglasses, the angle formed by the polarization axis of the emitted light and the transmission axis of the polarizing filter is Depending on the situation, the screen may become dark and the visibility of the image may deteriorate. Therefore, a liquid crystal display protective plate has been studied that can suppress deterioration of image visibility when viewing the screen of the liquid crystal display through a polarizing filter. For example, in Patent Document 3, a scratch-resistant resin plate having a cured film formed on at least one surface of a resin substrate is used, and the in-plane retardation value (hereinafter also referred to as "Re value") is 85 to A liquid crystal display protective plate with a thickness of 300 nm is disclosed (claim 1).

Japanese Patent Application Laid-Open No. 2004-299199 Japanese Patent Application Laid-Open No. 2006-103169 JP-A-2010-085978

The Re value of the resin plate used for the liquid crystal display protective plate may drop outside the desired range due to heat applied after the resin plate is manufactured, such as in the process of forming the functional layer. In this case, there is a risk that the visibility of the image will be significantly degraded particularly when viewing the liquid crystal display through a polarizing filter such as polarized sunglasses.

The present invention has been made in view of the above circumstances, and includes a functional layer having an in-plane retardation value (Re value) within a suitable range and having good visibility of a liquid crystal display through a polarizing filter. An object of the present invention is to provide a method for manufacturing a liquid crystal display protective plate having a

The present invention provides the following methods [1] to [5] for manufacturing a liquid crystal display protective plate.
[1] A method for manufacturing a liquid crystal display protective plate, comprising the step (X) of preparing a resin plate and the step (Y) of bonding a functional imparting film to the resin plate,
The step (Y) is performed under the condition that the temperature of the resin plate does not exceed 60°C,
The in-plane retardation value (R1) of the resin plate is 50 to 210 nm,
The in-plane retardation value (R2) of the liquid crystal display protective plate is 50 to 210 nm,
Liquid crystal display protection, wherein the ratio (R2/R1) of the in-plane retardation value (R2) of the liquid crystal display protective plate to the in-plane retardation value (R1) of the resin plate is 0.9 to 1.1. Board manufacturing method.

[2] The method for producing a liquid crystal display protective plate according to [1], wherein the resin plate is a thermoplastic resin laminate in which a methacrylic resin-containing layer is laminated on at least one surface of a polycarbonate resin-containing layer.

[3] Step (X) is
a step of co-extrusion from a T-die in a molten state of the thermoplastic resin laminate in which the methacrylic resin-containing layer is laminated on at least one surface of the polycarbonate resin-containing layer;
While forming a bank between the first cooling roll and the second cooling roll, the molten thermoplastic resin laminate is sandwiched, and after the thermoplastic resin laminate is wound around the second cooling roll, a third cooling roll is formed. A step of cooling by wrapping around a cooling roll;
The method for producing a liquid crystal display protective plate according to [2], comprising the step of taking the thermoplastic resin laminate after cooling with a take-up roll.

[4] The function-imparting film comprises a base film and at least one functional layer laminated on the surface of the base film,
The method for manufacturing a liquid crystal display protective plate according to any one of [1] to [3], wherein the in-plane retardation value (R3) of the base film is 10 nm or less.
[5] The method of manufacturing a liquid crystal display protective plate according to [4], wherein the base film is made of acrylic resin or triacetylcellulose resin.

According to the present invention, the in-plane retardation value (Re value) is within a suitable range, and the visibility of the liquid crystal display through a polarizing filter is good. can be provided.

1 is a schematic cross-sectional view of a liquid crystal display protective plate according to a first embodiment of the invention; FIG. FIG. 5 is a schematic cross-sectional view of a liquid crystal display protection plate of a second embodiment according to the invention; 1 is a schematic diagram of an extruded resin plate manufacturing apparatus according to one embodiment of the present invention. FIG.

"Liquid crystal display protection plate"
TECHNICAL FIELD The present invention relates to a method for manufacturing a liquid crystal display protective plate having a resin plate and a function-imparting film attached to at least one surface of the resin plate. The liquid crystal display protective plate can be suitably used for a liquid crystal display and a touch panel display in which a liquid crystal display and a touch panel are combined.
The resin plate is preferably a thermoplastic resin laminate in which a methacrylic resin-containing layer is laminated on at least one surface of a polycarbonate resin-containing layer. The polycarbonate resin-containing layer is a layer containing polycarbonate resin (PC), and the methacrylic resin-containing layer is a layer containing methacrylic resin (PM). Polycarbonate resin (PC) has excellent impact resistance, and methacrylic resin (PM) has excellent gloss, transparency, and surface hardness. Therefore, the liquid crystal display protective plate of the present invention containing the resin plate laminated with these resins is excellent in gloss, transparency, impact resistance and surface hardness.

(resin plate)
<Methacrylic resin-containing layer>
The methacrylic resin-containing layer contains one or more methacrylic resins (PM). A methacrylic resin (PM) is a homopolymer or copolymer containing structural units derived from one or more methacrylic acid esters. From the viewpoint of transparency, the content of methacrylic acid ester monomer units in the methacrylic resin (PM) is preferably 50% by mass or more, more preferably 80% by mass or more, and particularly preferably 90% by mass or more, It may be 100% by mass.

Preferred methacrylates include, for example, methyl methacrylate (MMA), ethyl methacrylate, butyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2-ethylhexyl methacrylate, 2-hydroxyethyl methacrylate; hydrocarbon esters; methacrylic acid polycyclic aliphatic hydrocarbon esters; From the viewpoint of transparency, the methacrylic resin (PM) preferably contains MMA units, and the content of the MMA units in the methacrylic resin (PM) is preferably 50 mass% or more, more preferably 80 mass% or more, and particularly It is preferably 90% by mass or more, and may be 100% by mass.

The methacrylic resin (PM) may contain structural units derived from one or more monomers other than the methacrylic acid ester. Other monomers include methyl acrylate (MA), ethyl acrylate, butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate, and 2-hydroxyethyl acrylate. acrylic acid esters; styrenes; acrylonitrile, methacrylonitrile; maleic anhydride, phenylmaleimide, cyclohexylmaleimide; Among them, MA is preferable from the viewpoint of transparency. For example, a copolymer of MMA and MA is preferred because of its excellent transparency. The content of MMA in this copolymer is preferably 80% by mass or more, more preferably 85% by mass or more, particularly preferably 90% by mass or more, and may be 100% by mass.

A methacrylic resin (PM) is preferably obtained by polymerizing one or more methacrylic acid esters including MMA, and optionally other monomers. When multiple types of monomers are used, usually, the multiple types of monomers are mixed to prepare a monomer mixture, and then the mixture is polymerized. The polymerization method is not particularly limited, and radical polymerization methods such as bulk polymerization, suspension polymerization, solution polymerization, and emulsion polymerization are preferred from the viewpoint of productivity.

The weight average molecular weight (Mw) of the methacrylic resin (PM) is preferably 40,000-500,000. When Mw is 40,000 or more, the methacrylic resin-containing layer has excellent scratch resistance and heat resistance, and when Mw is 500,000 or less, the methacrylic resin-containing layer has excellent moldability.
In this specification, unless otherwise specified, "Mw" is a standard polystyrene conversion value measured using gel permeation chromatography (GPC).

The methacrylic resin-containing layer can comprise methacrylic resin (PM) and optionally one or more other polymers.
For example, the methacrylic resin-containing layer can be made of a methacrylic resin composition (MR) containing a methacrylic resin (PM) and an SMA resin (S) (hereinafter also simply referred to as a resin composition (MR)).
As used herein, the term "SMA resin" includes structural units derived from one or more aromatic vinyl compounds and structural units derived from one or more acid anhydrides including maleic anhydride (MAH), More preferably, it is a copolymer containing a structural unit derived from a methacrylic acid ester.
The methacrylic resin composition (MR) can preferably contain 5-80% by weight of methacrylic resin (PM) and 95-20% by weight of SMA resin (S).

The SMA resin (S) is a copolymer containing structural units derived from one or more aromatic vinyl compounds and one or more acid anhydrides including MAH.
Examples of aromatic vinyl compounds include styrene (St); nucleus alkyl-substituted styrenes such as 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 4-ethylstyrene, and 4-tert-butylstyrene; α-methylstyrene and α-alkyl-substituted styrenes such as 4-methyl-α-methylstyrene; Among them, styrene (St) is preferable from the viewpoint of availability. From the viewpoint of the transparency and moisture resistance of the resin composition (MR), the content of the aromatic vinyl compound monomer units in the SMA resin (S) is preferably 50 to 85% by mass, more preferably 55 to 82%. % by weight, particularly preferably 60 to 80% by weight.
As the acid anhydride, at least maleic anhydride (MAH) is used from the viewpoint of availability, and other acid anhydrides such as citraconic anhydride and dimethyl maleic anhydride can be used as necessary. From the viewpoint of transparency and heat resistance of the resin composition (MR), the content of the acid anhydride monomer unit in the SMA resin (S) is preferably 15-50% by mass, more preferably 18-45% by mass. %, particularly preferably 20 to 40% by weight.

The SMA resin (S) can contain structural units derived from one or more methacrylic acid ester monomers in addition to the aromatic vinyl compound and the acid anhydride. Examples of methacrylic acid ester units include structural units that can constitute methacrylic resins (PM), and from the viewpoint of the heat resistance and transparency of the SMA resin (S), MMA is preferable. From the viewpoint of the transparency of the resin plate, the content of the methacrylate monomer units in the SMA resin (S) is preferably 1 to 35% by mass, more preferably 3 to 30% by mass, and particularly preferably 5 to 35% by mass. 26% by mass. In this case, the content of aromatic vinyl compound monomer units is preferably 50 to 84% by mass, and the content of acid anhydride monomer units is preferably 15 to 49% by mass.

The SMA resin (S) may have structural units derived from monomers other than the aromatic vinyl compound, acid anhydride, and methacrylic acid ester. As other monomers, those mentioned above in the description of the methacrylic resin (PM) can be used. The content of other monomer units in the SMA resin (S) is preferably 10% by mass or less, more preferably 5% by mass or less, and particularly preferably 2% by mass or less.

The SMA resin (S) is obtained by polymerizing an aromatic vinyl compound, an acid anhydride, optionally a methacrylic acid ester, and optionally other monomers. In this polymerization, usually, a monomer mixture is prepared by mixing a plurality of types of monomers, and then the polymerization is carried out. The polymerization method is not particularly limited, and radical polymerization methods such as bulk polymerization and solution polymerization are preferred from the viewpoint of productivity.

The Mw of the SMA resin (S) is preferably from 40,000 to 300,000. When Mw is 40,000 or more, the methacrylic resin-containing layer has excellent scratch resistance and impact resistance, and when Mw is 300,000 or less, the methacrylic resin-containing layer has excellent moldability.

The resin composition (MR) is obtained, for example, by mixing a methacrylic resin (PM) and an SMA resin (S). Mixing methods include a melt mixing method and a solution mixing method. In the melt-mixing method, a single-screw or multi-screw kneader; open-roll, Banbury mixer, kneader, or other melt-kneader is used, and if necessary, an inert gas such as nitrogen gas, argon gas, and helium gas is used. Melt-kneading can be performed in an atmosphere. In the solution mixing method, the methacrylic resin (A) and the SMA resin (S) can be dissolved in an organic solvent such as toluene, tetrahydrofuran, and methyl ethyl ketone and mixed.

The methacrylic resin-containing layer comprises a methacrylic resin composition (MR), which comprises a methacrylic resin (PM), an SMA resin (S), and optionally one or more other polymers. can contain.
Other polymers are not particularly limited, and other thermoplastic resins such as polyolefins such as polyethylene and polypropylene, polyamides, polyphenylene sulfides, polyetheretherketones, polyesters, polysulfones, polyphenylene oxides, polyimides, polyetherimides, and polyacetals. thermosetting resins such as phenol resins, melamine resins, silicone resins, and epoxy resins; The content of the other polymer in the methacrylic resin-containing layer is preferably 10% by mass or less, more preferably 5% by mass or less, and particularly preferably 2% by mass or less.

The methacrylic resin-containing layer can contain various additives as needed. Additives include antioxidants, heat deterioration inhibitors, UV absorbers, light stabilizers, lubricants, release agents, polymer processing aids, antistatic agents, flame retardants, dyes/pigments, organic pigments, and light diffusion. matting agents, impact modifiers such as core-shell particles and block copolymers, and phosphors. The content of the additive can be appropriately set within a range that does not impair the effects of the present invention. With respect to 100 parts by mass of the resin constituting the methacrylic resin-containing layer, for example, the content of the antioxidant is 0.01 to 1 part by mass, the content of the ultraviolet absorber is 0.01 to 3 parts by mass, and the light stabilizer is preferably 0.01 to 3 parts by mass, the lubricant content is preferably 0.01 to 3 parts by mass, and the dye/pigment content is preferably 0.01 to 3 parts by mass.

When the methacrylic resin (PM) contains other polymers and/or additives, the addition timing may be during or after the polymerization of the methacrylic resin (PM).
When the methacrylic resin composition (MR) contains other polymers and/or additives, the timing of addition may be during the polymerization of the methacrylic resin (PM) and/or the SMA resin (S), or during mixing of these resins. It may be during or after mixing.

From the viewpoint of the stability of hot-melt molding, the melt volume flow rate (MVR) of the constituent resin of the methacrylic resin-containing layer is preferably 0.5 to 20 cm ³ /10 minutes. In this specification, the MVR of the constituent resin of the methacrylic resin-containing layer is a value measured under conditions of 230° C. and a load of 37.3 N according to ISO-1133.

<Layer containing polycarbonate resin>
The polycarbonate resin-containing layer contains one or more polycarbonate resins (PC). Polycarbonate resin (PC) is preferably obtained by copolymerizing one or more dihydric phenols and one or more carbonate precursors. As a production method, an interfacial polymerization method in which an aqueous solution of dihydric phenol and an organic solvent solution of a carbonate precursor are reacted at the interface, and a dihydric phenol and a carbonate precursor are reacted under high temperature, reduced pressure, and no solvent conditions. A transesterification method and the like can be mentioned.

Dihydric phenols include 2,2-bis(4-hydroxyphenyl)propane (commonly known as bisphenol A), 1,1-bis(4-hydroxyphenyl)ethane, 1,1-bis(4-hydroxyphenyl)cyclohexane, 2,2-bis(3-methyl-4-hydroxyphenyl)propane, 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane, bis(4-hydroxyphenyl)sulfide, and bis(4- hydroxyphenyl) sulfone and the like, among which bisphenol A is preferred. Carbonate precursors include carbonyl halides such as phosgene; carbonate esters such as diphenyl carbonate; haloformates such as dihaloformates of dihydric phenols;

Mw of the polycarbonate resin (PC) is preferably 10,000 to 100,000, more preferably 20,000 to 70,000. When Mw is 10,000 or more, the polycarbonate resin-containing layer has excellent impact resistance and heat resistance, and when Mw is 100,000 or less, the polycarbonate resin-containing layer has excellent moldability.

A commercially available polycarbonate resin (PC) may be used. "Calibur (registered trademark)" and "SD Polyca (registered trademark)" manufactured by Sumika Styron Polycarbonate Co., Ltd., "Iupilon / Novarex (registered trademark)" manufactured by Mitsubishi Engineering-Plastics Co., Ltd., "Taflon (registered trademark)" manufactured by Idemitsu Kosan Co., Ltd. Trademark)” and “Panlite (registered trademark)” manufactured by Teijin Chemicals Limited.

The polycarbonate resin-containing layer may optionally contain one or more other polymers and/or various additives. As other polymers and various additives, the same ones as those mentioned above in the description of the methacrylic resin-containing layer can be used. The content of the other polymer in the polycarbonate resin-containing layer is preferably 15% by mass or less, more preferably 10% by mass or less, and particularly preferably 5% by mass or less. The content of the additive can be appropriately set within a range that does not impair the effects of the present invention. With respect to 100 parts by mass of polycarbonate resin (PC), the content of antioxidant is 0.01 to 1 part by mass, the content of ultraviolet absorber is 0.01 to 3 parts by mass, and the content of light stabilizer is 0. 0.01 to 3 parts by mass, the content of the lubricant is preferably 0.01 to 3 parts by mass, and the content of the dye/pigment is preferably 0.01 to 3 parts by mass.
When other polymers and/or additives are added to the polycarbonate resin (PC), the addition timing may be during or after the polymerization of the polycarbonate resin (PC).

From the viewpoint of the stability of heat-melt molding, the melt volume flow rate (MVR) of the constituent resin of the polycarbonate resin-containing layer is preferably 1 to 20 cm ³ /10 minutes. In this specification, the MVR of the constituent resin of the polycarbonate resin-containing layer is a value measured under conditions of 300° C. and a load of 11.8 N according to ISO-1133.

<Thickness of resin plate and each layer>
The overall thickness of the resin plate used for the liquid crystal display protective plate of the present invention is preferably 0.4 to 2 mm, more preferably 0.5 to 1.5 mm. If it is too thin, the rigidity may become insufficient, and if it is too thick, it may hinder weight reduction of the liquid crystal display or the touch panel display including the same.
The thickness of the methacrylic resin-containing layer is not particularly limited, and is preferably 20 to 200 μm, more preferably 25 to 150 μm, particularly preferably 30 to 100 μm, because of the excellent balance between scratch resistance and impact resistance. The thickness of the polycarbonate resin-containing layer is preferably 0.3-4.9 mm, more preferably 0.6-2.9 mm.

<Laminate structure>
The resin plate contained in the liquid crystal display protective plate of the present invention may have other resin layers as long as the methacrylic resin-containing layer is laminated on at least one surface of the polycarbonate resin-containing layer. The laminate structure of the resin plate includes a two-layer structure of polycarbonate resin-containing layer and methacrylic resin-containing layer; a three-layer structure of methacrylic resin-containing layer-polycarbonate resin-containing layer-methacrylic resin-containing layer; and a methacrylic resin-containing layer-polycarbonate resin-containing layer. - three-layer structure of other resin layer; three-layer structure of other resin layer - methacrylic resin-containing layer - polycarbonate resin-containing layer;
Both sides of the resin plate have excellent scratch resistance, and warping of the resin plate due to changes in humidity, etc. is suppressed. Therefore, the resin plate has a laminated structure in which methacrylic resin-containing layers are laminated on both sides of a polycarbonate resin-containing layer. is preferred.

<In-plane retardation value (R1) of resin plate>
Although the details will be described later, in order to improve the visibility of the liquid crystal display through a polarizing filter such as polarized sunglasses, in the present invention, the in-plane retardation value (R2 ) is 50 to 210 nm. Therefore, in the present invention, the in-plane retardation value (R1) of the resin plate used for manufacturing the liquid crystal display protective plate is set to 50 to 210 nm.

(functionality imparting film)
The function-imparting film to be laminated on the surface of the resin plate may be any film capable of imparting various functions, and preferably comprises a base film and at least one functional layer laminated on the surface of the base film. .
The in-plane retardation value (R3) of the base film of the function-imparting film is preferably 10 nm or less. If the in-plane retardation value (R3) of the base film is 10 nm or less and is sufficiently smaller than the in-plane retardation value (R1) of the resin plate, the retardation of the finally obtained liquid crystal display protective plate It is easy to control the value (R2) within the above range.

A known material can be used for the base film, and examples thereof include polyethylene terephthalate (PET), triacetyl cellulose (TAC) resin, polycarbonate resin, acrylic resin, and polyolefin. Among them, the in-plane retardation value (R3) of the base film can be made smaller, and the retardation value (R2) of the finally obtained liquid crystal display protective plate can be easily controlled within the above range. etc. are preferred. Acrylic resins are particularly preferred from the viewpoint of resistance to warping due to water absorption.

Functional layers include scratch resistance (hard coat properties) and/or a cured film with low reflectivity for improving visibility, an antiglare film that suppresses glare, an antifouling film that suppresses the adhesion of dirt, and a dust-repellent film. Examples include an antistatic film that suppresses adhesion and a transparent conductive film that imparts conductivity necessary for touch panels. A plurality of functional layers may be provided on the resin plate.

The thickness of the functional layer can be appropriately designed according to desired functions and the like.
For example, the thickness of the scratch-resistant (hard coat) cured film (scratch-resistant layer) is preferably 2 to 30 μm, more preferably 3 to 10 μm. If it is too thin, the surface hardness will be insufficient, and if it is too thick, cracks may occur due to bending during the manufacturing process.
For example, the thickness of the low-reflection cured coating (low-reflection layer) is preferably 80-200 nm, more preferably 100-150 nm. If it is too thin or too thick, the low reflection performance may become insufficient.

The method of forming the functional layer on the surface of the base film is not particularly limited.
For example, the surface of the base film is coated with a preferably liquid curable composition containing a thermosetting compound or an active energy ray-curable compound, and the coating is cured by heating or irradiation with an active energy ray. A coating can be formed. An active energy ray-curable compound is a compound having a property of being cured by being irradiated with an active energy ray such as an electron beam or ultraviolet rays. Examples of thermosetting compositions include polyorganosiloxane-based and cross-linked acrylic-based compositions. Examples of the active energy ray-curable composition include those containing a curable compound such as a monofunctional or polyfunctional acrylate monomer or oligomer and a photopolymerization initiator. The cured film can be formed using a commercially available hard coating agent. Another method for forming a functional layer on the surface of a base film is to add a functional material or a functional material precursor to water and an organic solvent. Examples thereof include a method of applying a dispersed or dissolved liquid, and drying or heating.

(Embodiment of liquid crystal display protection plate)
1 and 2 are schematic cross-sectional views of liquid crystal display protection plates of first and second embodiments according to the present invention. In the figure, symbols 1 and 2 are liquid crystal display protective plates, symbols 16X and 16Y are resin plates, symbol 17 is a functional imparting film, symbol 21 is a polycarbonate resin-containing layer, symbols 22, 22A and 22B are methacrylic resin-containing layers, and symbols. Reference numeral 23 denotes a base film, and reference numeral 24 denotes a functional layer. The liquid crystal display protective plate 1 of the first embodiment has a resin plate 16X having a two-layer structure of a polycarbonate resin-containing layer 21 and a methacrylic resin-containing layer 22, and a function imparting film 17 is attached to one surface of the resin plate 16X. The liquid crystal display protective plate 2 of the second embodiment has a three-layer structure of a first methacrylic resin-containing layer 22A, a polycarbonate resin-containing layer 21, and a second methacrylic resin-containing layer 22B. A property-imparting film 17 is laminated. The function-imparting film 17 is obtained by laminating at least one functional layer 24 on the surface of the base film 23 . In the liquid crystal display protective plates 1 and 2, the resin plate 16X or 16Y and the base film 23 of the function imparting film 17 are bonded together.
The configurations of the resin plate, the function-imparting film, and the liquid crystal display protective plate can be changed in design as appropriate. For example, in FIG. 1, the functionality-imparting film 17 is attached to the methacrylic resin-containing layer 22 side of the resin plate 16X, but the functionality-imparting film 17 is attached to the polycarbonate resin-containing layer 21 side of the resin plate 16X. good too.

(In-plane retardation value (R2) of liquid crystal display protective plate)
The in-plane retardation value (R2) of the liquid crystal display protective plate is set to 50 to 210 nm because the visibility of the liquid crystal display through a polarizing filter such as polarized sunglasses is improved. If it is smaller or larger than this range, the visibility of the liquid crystal display through the polarizing filter may be poor. Specifically, when R2 exceeds 210 nm, when the liquid crystal display is viewed through a polarizing filter, the difference in transmittance for each wavelength in the visible light range becomes large, and various colors appear mixed, making the image difficult to view. becomes difficult. If R2 is less than 50 nm, the transmittance of all wavelengths in the visible light range is greatly reduced, resulting in an entirely black image that is difficult to see. Within the range of 50 to 210 nm for R2, a larger value tends to result in a brighter image, and a smaller value tends to reduce the number of visible mixed colors. In particular, R2 is preferably 60 to 200 nm, more preferably 80 to 180 nm, and particularly preferably 100 to 150 nm, because the balance between brightness and color is good and the visibility is excellent when viewing the liquid crystal display through a polarizing filter. be.

[Method for manufacturing liquid crystal display protective plate]
The manufacturing method of the liquid crystal display protective plate of the present invention has a step (X) of preparing a resin plate and a step (Y) of laminating a functional imparting film to the resin plate.

(Step (X))
The resin plate can be produced by a known method such as a cast molding method, an injection molding method, an extrusion molding method, etc. The extrusion molding method is preferable in terms of excellent production efficiency, and the co-extrusion molding method is particularly preferable.
The constituent resins of the polycarbonate resin-containing layer and the methacrylic resin-containing layer are melted by heating, respectively, and a thermoplastic resin laminate in which the methacrylic resin-containing layer is laminated on at least one surface of the polycarbonate resin-containing layer is formed, and a wide discharge port is provided. It is co-extruded in a molten state from a T-die.
Examples of the stacking method include a feed block method in which layers are stacked before flowing into the T die, and a multi-manifold method in which layers are stacked inside the T die. A multi-manifold system is preferable from the viewpoint of improving interface smoothness between the layers of the resin plate and from the viewpoint of excellent thickness accuracy of each layer.

The molten thermoplastic resin laminate co-extruded from the T-die is cooled using a plurality of cooling rolls. In the present invention, three or more cooling rolls adjacent to each other are used, and the molten thermoplastic resin laminate is placed between the nth (where n≧1) cooling roll and the n+1th cooling roll. It is cooled by repeating the operation of pinching and winding around the (n+1)th cooling roll a plurality of times from n=1. For example, if three chill rolls are used, the number of repetitions is two.

Examples of the cooling roll include a metal roll and an elastic roll having a metal thin film on its outer periphery (hereinafter also referred to as a metal elastic roll). Metal rolls include drilled rolls and spiral rolls. The surface of the metal roll may be a mirror surface, or may have a pattern, unevenness, or the like. A metal elastic roll consists of, for example, a shaft roll made of stainless steel or the like, a metal thin film made of stainless steel or the like covering the outer peripheral surface of the shaft roll, and a fluid enclosed between the shaft roll and the metal thin film. , can exhibit elasticity due to the presence of fluid. The thickness of the metal thin film is preferably about 2 to 5 mm. The metal thin film preferably has bendability, flexibility, etc., and preferably has a seamless structure without weld joints. A metal elastic roll provided with such a metal thin film is excellent in durability, and if the metal thin film is mirror-finished, it can be handled in the same manner as a normal mirror-finished roll. It is easy to use because it becomes a roll that can transfer the shape.

The resin plate obtained after cooling is taken off by take-off rolls. The above steps of co-extrusion, cooling, and take-off are performed continuously.

FIG. 3 shows a schematic diagram of a manufacturing apparatus including a T die 11, first to third cooling rolls 12 to 14, and a pair of take-up rolls 15 as an embodiment. The thermoplastic resin laminate coextruded from the T-die 11 is cooled using the first to third cooling rolls 12 to 14 and taken by a pair of take-off rolls 15 . In the illustrated example, the third chill roll 14 is "the last chill roll around which the thermoplastic resin laminate is wound (hereinafter also simply referred to as the last chill roll)".
A fourth and subsequent cooling rolls may be installed adjacent to the rear stage of the third cooling roll 14 . In this case, the cooling roll on which the thermoplastic resin layered body is finally wound is the "last cooling roll". In addition, a transport roll can be installed between a plurality of adjacent cooling rolls and a take-up roll as necessary, but the transport roll is not included in the "cooling roll".
It should be noted that the configuration of the manufacturing apparatus can be appropriately modified within the scope of the present invention.

In order to set the in-plane retardation value (R2) of the finally manufactured liquid crystal display protective plate to 50 to 210 nm, in the present invention, the in-plane retardation value (R1) of the resin plate is 50 to 210 nm. to produce a resin plate.
"Retardation" is the phase difference between light in the direction of the molecular main chain and light in the direction perpendicular to it. In general, polymers can be formed into arbitrary shapes by heat-melting and molding, but it is known that stress generated during heating and cooling processes causes molecules to be oriented and retardation to occur. Therefore, it is necessary to control the orientation of the molecules in order to control the retardation. Orientation of the molecules is caused, for example, by stress during molding near the glass transition temperature of the polymer. In this specification, "retardation" indicates in-plane retardation unless otherwise specified.
By optimizing the production conditions in the process of extrusion molding, the orientation of the molecules can be controlled, thereby optimizing the in-plane retardation value (R1) of the resin plate after extrusion molding.

As used herein, unless otherwise specified, the "peripheral velocity ratio" is the ratio of the peripheral velocity of any other chill roll or take-up roll to the second chill roll. The peripheral speed of the second cooling roll is V2, the peripheral speed of the third cooling roll is V3, and the peripheral speed of the take-up roll is V4.
For example, the bank amount, the total temperature (TT) of the thermoplastic resin laminate at the position where it is peeled off from the last chill roll, the peripheral speed of the take-up roll (V4) and the peripheral speed of the second chill roll (V2) By adjusting the peripheral speed ratio (V4/V2), etc., the in-plane retardation value (R1) of the resin plate can be controlled within a desired range.

In this specification, a "bank" is a resin pool formed in the gap between the first cooling roll and the second cooling roll. As the bank amount increases, the in-plane retardation value (Re value) tends to increase. The reason for this is that when the molten resin flows from the position where the resin puddle occurs to the minimum gap between the first cooling roll and the second cooling roll, the molecules are oriented due to the difference in flow velocity inside the resin along with the cooling of the resin. I think that the. By relatively increasing the amount of resin supplied to the chill roll or relatively decreasing the rotation speed of the chill roll, it is possible to adjust the bank to a relatively large size.

The total temperature (TT) of the thermoplastic resin laminate at the position where it is peeled off from the last cooling roll (the third cooling roll in FIG. 3) is preferably −2° C. or higher with respect to the glass transition temperature of the polycarbonate resin-containing layer, and more A temperature of preferably -2°C to +20°C, particularly preferably +0.1°C to +20°C, most preferably +0.1°C to +15°C is adjusted.
If the TT is too low with respect to the glass transition temperature of the polycarbonate resin-containing layer, the shape of the final cooling roll (the third cooling roll in FIG. 3) may be transferred to the resin plate, resulting in increased warping. On the other hand, if the TT is too high relative to the glass transition temperature of the resin layer in contact with the last cooling roll (the third cooling roll in FIG. 3), the surface properties of the resin plate may deteriorate.

The Re value tends to increase as the circumferential velocity ratio (V4/V2) increases. The reason is presumed as follows. The TT is preferably −2° C. or higher, more preferably −2° C. to +20° C. relative to the glass transition temperature of the polycarbonate resin-containing layer. When a large tensile stress is applied to , the Re value is presumed to increase because this is a temperature range in which the molecules of the resin tend to be oriented.
TT is controlled to preferably −2° C. or higher, more preferably −2° C. to +20° C. with respect to the glass transition temperature of the polycarbonate resin-containing layer, and the peripheral speed ratio (V4/V2) is adjusted within a suitable range. By doing so, the Re value can be controlled within a suitable range. Specifically, in the production method of the present invention, the peripheral velocity ratio (V4/V2) is preferably 0.98 or more and less than 1.0. When the peripheral velocity ratio (V4/V2) is 1.0 or more, the Re value may exceed 210 nm. If the circumferential velocity ratio (V4/V2) is less than 0.98, Re may be less than 50 nm. From the viewpoint of optimizing the Re value, the circumferential velocity ratio (V4/V2) is more preferably 0.985 to 0.995.

(Step (Y))
In step (Y), a function-imparting film is attached to the surface of the resin plate prepared in step (X).
As a method of directly forming a functional layer on a resin plate instead of laminating a functional-imparting film, a functional material or a precursor of a functional material is prepared using a roll coater, a die coater, a flow coater, or the like. a method of applying a liquid coating liquid containing the functional material, a method of applying a liquid coating liquid containing a functional material or a precursor of the functional material by a dipping method, and a vapor phase method such as a vapor deposition method. A method of directly forming a functional layer on a resin plate generally includes a step of heating the resin plate at a relatively high temperature for drying or curing a coating liquid or vapor phase film formation. Due to this relatively high temperature heating step, the in-plane retardation value (Re value) of the resin plate may decrease, and the Re value may fall outside the preferred range.
In the present invention, lamination of a function-imparting film capable of imparting a functional layer at a lower temperature than a method of directly forming a functional layer on a resin plate is adopted. Furthermore, in order to suppress a decrease in the in-plane retardation value (Re value) of the resin plate due to heating, the bonding is performed under the condition that the temperature of the resin plate does not exceed 60°C, preferably 40 to 60°C. .
In the production method of the present invention, a pressure-sensitive adhesive or an adhesive can be used to bond the function-imparting film to the resin plate, if necessary. A certain amount of heat is required for lamination in order to thinly and evenly spread the pressure-sensitive adhesive or adhesive on the resin plate. However, the temperature of the resin plate should not exceed 60°C. In order to maintain the temperature of the resin plate at 60° C. or less in the bonding process, an adhesive that does not require irradiation with active energy rays and heating at a temperature exceeding 60° C. is used in the bonding process.
In addition, the temperature of the resin plate should not exceed 60°C in the laminating step. There is no particular problem because there is no influence of

In the production method of the present invention, the lamination step is performed under the condition that the temperature of the resin plate does not exceed 60° C., thereby suppressing a decrease in the in-plane retardation value of the resin plate in the lamination step. The ratio (R2/R1) of the in-plane retardation value (R2) of the liquid crystal display protective plate to the retardation value (R1) of 0.9 to 1.1. If R2/R1 is within this range, the change in the in-plane retardation value (Re value) of the resin plate in the bonding process is small, and the in-plane retardation value (R2) of the liquid crystal display protective plate is within a suitable range. can be easily controlled within (specifically, within the range of 50 to 210 nm).
As described above, the in-plane retardation value (R3) of the base film of the function-imparting film is preferably 10 nm or less. If the in-plane retardation value (R3) of the base film is 10 nm or less and is sufficiently smaller than the in-plane retardation value (R1) of the resin plate, the surface of the liquid crystal display protective plate obtained after the bonding process. The retardation value (R2) within the range can be easily controlled within a suitable range (specifically, within a range of 50 to 210 nm), which is preferable.

The method for manufacturing a liquid crystal display protective plate of the present invention can have other steps than the above steps (X) and (Y), if necessary. Suppressing the decrease in the in-plane retardation value of the resin plate due to heat, the in-plane retardation value (R2) of the finally obtained liquid crystal display protective plate is within a suitable range (specifically 50 to 210 nm) In order to easily control the temperature within the range), it is preferable that the temperature of the resin plate does not exceed 60° C. in other steps as well.

As described above, according to the manufacturing method of the liquid crystal display protective plate of the present invention, the bonding process is performed under the condition that the temperature of the resin plate does not exceed 60° C., so that the letter in the plane of the resin plate in the bonding process is reduced. A liquid crystal display having a functional layer that suppresses a decrease in retardation value (Re value), has an in-plane retardation value (R2) within a suitable range, and has good visibility of the liquid crystal display through a polarizing filter. Protective plates can be manufactured.

[Use]
Liquid crystal display protective plates are used, for example, in ATMs of financial institutions such as banks; vending machines; televisions; It is suitable as a protective plate for liquid crystal displays or touch panel displays used in digital information equipment such as game machines, copiers, facsimiles, and car navigation systems.

Examples and comparative examples according to the present invention will be described.
[Evaluation items and evaluation methods]
Evaluation items and evaluation methods are as follows.
(MVR)
The MVR of the resin was measured according to ISO-1133 using a melt indexer ("TAKARA L241-153", manufactured by Techno Seven Co., Ltd.).

(In-plane retardation value (Re value))
A 100 mm square test piece was cut out from a resin plate, a function-imparting film, or a liquid crystal display protective plate. After leaving the test piece in an environment of 25° C.±3° C. for 10 minutes or longer, the Re value was measured using “WPA-100(-L)” manufactured by Photonic Lattice Co., Ltd. The measurement point was the central portion of the test piece.

(Pencil hardness)
In order to evaluate the scratch resistance of the liquid crystal display protective plate having a hard coat layer (hardened film) formed on the surface, a table moving pencil scratch tester (model P, manufactured by Toyo Seiki Co., Ltd.) was used to test the surface of the resin plate. and the hard coat layer (cured film) side surface of the liquid crystal display protective plate were measured for pencil scratch hardness. Under conditions of an angle of 45° and a load of 750 g, the surface of the object to be measured was scratched while pressing the lead of a pencil, and the presence or absence of a scratch mark was confirmed. The hardness of the lead of the pencil gradually increased, and the hardness of the lead that was one level softer than the point at which the scar was produced was used as the scratch resistance data.

(Anti-reflection)
In order to evaluate the antireflection properties of the liquid crystal display protective plate with a low-reflection layer formed on the surface, the resin plate and the liquid crystal display protective plate with a low-reflection layer formed on the surface were measured with a spectral reflectance measuring machine (model PC-3100). , manufactured by Shimadzu Corporation) was used to evaluate the minimum reflectance in the wavelength range of 380 to 780 nm. In the case of the liquid crystal display protective plate, the measurement was performed by irradiating the surface of the low-reflection layer side with light. The antireflection effect was evaluated according to the following criteria.
○ (Good): The minimum reflectance was less than 1.5%.
(triangle|delta) (good): The minimum reflectance was 1.5% or more.

(Visibility when wearing polarized sunglasses)
Using a running saw, a 100 mm square test piece was cut out from the resin plate or liquid crystal display protective plate. Next, an image was displayed by placing a color liquid crystal display at a position 35 cm away from the eyes. Then, the test piece was arranged parallel to the screen of the display at a position 30 cm away from the eye in front of the liquid crystal display.
First, the image was visually observed through the test piece in the thickness direction without wearing polarized sunglasses. Next, while wearing polarized sunglasses, the subject tilted his/her head to the right and left while facing the image, and visually observed the image in the same manner as described above. Visibility was evaluated according to the following criteria.
◯ (good): There was no noticeable change in the appearance of the image depending on whether the polarized sunglasses were worn or not, and the image was visible without any problem regardless of whether the polarized sunglasses were worn or not.
x (poor): When the head was tilted at a certain angle while wearing polarized sunglasses, the image became darker or darker, and the visibility of the image decreased.

[material]
The materials used are as follows.
<Methacrylic resin (PM)>
(PM1) Polymethyl methacrylate (PMMA), "Parapet (registered trademark) HR" manufactured by Kuraray Co., Ltd. (MVR: 2.0 cm ³ /10 minutes).
<Methacrylic resin composition (MR)>
(MR1)
30 parts by mass of the above methacrylic resin (PM1) and 70 parts by mass of "RESISFY R-200" (styrene (St)-maleic anhydride (MAH)-methyl methacrylate (MMA) copolymer) manufactured by Denki Kagaku Kogyo Co., Ltd. and were supplied to a hopper of a twin-screw extruder, melt-kneaded at a cylinder temperature of 230° C., and extruded to obtain a methacrylic resin composition (MR1) in the form of pellets.
<Polycarbonate resin (PC)>
(PC1) “SD Polyca (registered trademark) PCX” manufactured by Sumika Styron Polycarbonate Co., Ltd. (MVR: 8 cm ³ /10 min, glass transition temperature: 151° C.).

[Reference Example 1] (Production and evaluation of resin plate (RP1))
A resin plate was extruded using a manufacturing apparatus as shown in FIG.
A methacrylic resin (PM1) melted using a 150 mmφ single screw extruder (manufactured by Toshiba Machine Co., Ltd.), a polycarbonate (PC1) melted using a 150 mmφ single screw extruder (manufactured by Toshiba Machine Co., Ltd.), and a 150 mmφ single screw. A methacrylic resin (PM1) melted using an extruder (manufactured by Toshiba Machine Co., Ltd.) is laminated through a multi-manifold die, and a thermoplastic resin laminate having a three-layer structure is co-extruded from a T-die. It was cooled using the third cooling roll, and the resin plate obtained after cooling was taken up by a pair of take-up rolls.
The first chill roll and the third chill roll were metal rigid rolls, and the second chill roll was a metal elastic roll. The amount of bank formed between the first cooling roll and the second cooling roll was kept small (condition of small amount of bank). The peripheral speed ratio (V3/V2) between the second cooling roll and the third cooling roll was adjusted to 1.003, and the peripheral speed ratio (V4/V2) between the second cooling roll and the take-up roll was adjusted to 0.995. It was adjusted. The total temperature (TT) of the thermoplastic resin laminate at the position where the thermoplastic resin laminate is peeled off from the last cooling roll (specifically, the third cooling roll) is the temperature of the second cooling roll and the third cooling roll. was adjusted to 130°C by controlling the The TT was measured using an infrared radiation thermometer, and the measurement point was the central portion in the width direction of the resin plate.
As described above, a resin plate (RP1) having a three-layer structure having a laminated structure of a methacrylic resin-containing layer (surface layer 1) - a polycarbonate resin-containing layer (inner layer) - a methacrylic resin-containing layer (surface layer 2) was obtained. The composition and thickness of the two methacrylic resin-containing layers were the same. The thickness of each layer of methacrylic resin (PM1)/polycarbonate resin (PC1)/methacrylic resin (PM1) was set to 75 μm/850 μm/75 μm at the central portion in the width direction of the resin plate. The average thickness (TC) of the entire resin plate was 1 mm, and the width of the resin plate was about 1500 mm. The obtained resin plate was cut along the extrusion direction to a length of about 1000 mm, and both ends in the width direction were cut off to a width of about 100 mm to obtain a rectangular sample resin plate for evaluation of about 1000 mm x about 1300 mm. got
Table 1 shows the laminated structure of the obtained resin plate, main molding conditions, and evaluation results. In addition, in the reference examples, examples, and comparative examples described in Tables 1 and 2, manufacturing conditions not described were common conditions. In the reference examples shown in Table 1, the bank amount was either "small" or "large". The amount of bank was adjusted by changing the amount of resin supplied to the cooling roll, and the size of the amount of bank was relatively evaluated visually.

[Reference Examples 2 to 4] (Production and evaluation of resin plates (RP2) to (RP4))
In the same manner as in Reference Example 1 except that the laminate structure and/or molding conditions are changed, a laminate structure of a methacrylic resin-containing layer (surface layer 1) - a polycarbonate resin-containing layer (inner layer) - a methacrylic resin-containing layer (surface layer 2) is provided. Resin plates (RP2) to (RP4) having a three-layer structure were obtained. Table 1 shows the laminated structure of the obtained resin plate, main molding conditions, and evaluation results.

[Production Example 1-1] (Production of base film (BF1-1))
A base having a thickness of 40 μm was prepared by a known method using a composition consisting of a block copolymer of methyl methacrylate (MMA) and butyl acrylate (BA) ("Clarity" manufactured by Kuraray Co., Ltd.) and a methacrylic resin (PM1). A film (BF1-1) was produced.
[Production Example 1-2] (Production of base film (BF1-2))
Using a composition (“Parapet GR” manufactured by Kuraray Co., Ltd.) consisting of crosslinked acrylic rubber particles and methacrylic resin (PM1), a base film (BF1-2) having a thickness of 40 μm was produced by a known method.

[Production Examples 2-1 and 2-2] (Production of Scratch Resistance Imparting Films (F1-1) and (F1-2))
On one side of the base film (BF1-1) obtained in Production Example 1-1, an ultraviolet curable hard coating liquid (UV-1700B manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) containing urethane acrylate as a curable compound is applied. Then, the coating film is cured by irradiating ultraviolet rays using an ultraviolet irradiation lamp to form a hard coat layer (cured film) having a thickness of 4 μm, and a scratch resistance imparting film (F1-1) is a functional imparting film. ) was produced (Production Example 2-1). During the above process, the temperature of the base film was measured with an infrared radiation thermometer at any time, and the maximum temperature was about 100°C.
By the same method, a hard coat layer (cured film) having a thickness of 4 μm is formed on one surface of the base film (BF1-2) obtained in Production Example 1-2, and a functional film, which is a resistant film, is formed. A scratch-imparting film (F1-2) was produced (Production Example 2-2).

[Production Example 3] (Production of low reflectance-imparting film (F2))
SiO ₂ sol (DTP-1 manufactured by Sumitomo Osaka Cement Co., Ltd.) was applied to one surface of the base film (BF1-1) obtained in Production Example 1-1, dried and cured by heating to a thickness of 100 nm. A low-reflection layer was formed to produce a low-reflection-imparting film (F2), which is a function-imparting film. During the above process, the temperature of the base film was measured with an infrared radiation thermometer at any time, and the maximum temperature was about 90°C.

[Example 1-1] (Production and evaluation of liquid crystal display protective plate)
On one side of the resin plate (RP1) obtained in Reference Example 1, the base film side of the scratch resistance-imparting film (F1-1) obtained in Production Example 2-1 is coated with an acrylic pressure-sensitive adhesive (DIC's CT -3088) at 40° C. to produce a liquid crystal display protective plate.
Table 2 shows the types of the resin plate and the function-imparting film used, the temperature of the resin plate in the bonding process, the evaluation results of the resin plate and the function-imparting film used, and the evaluation result of the obtained liquid crystal display protective plate.

[Examples 1-2, 2-1, 2-2, 3 to 7] (Production and evaluation of liquid crystal display protective plate)
A protective plate for a liquid crystal display was produced in the same manner as in Example 1-1, except that the types of resin plate and function-imparting film used and the temperature of the resin plate in the bonding process were changed.
Table 2 shows the types of the resin plate and the function-imparting film used, the temperature of the resin plate in the bonding process, the evaluation results of the resin plate and the function-imparting film used, and the evaluation result of the obtained liquid crystal display protective plate.

[Comparative Example 1] (Production and evaluation of liquid crystal display protective plate)
On one surface of the resin plate (RP1) obtained in Reference Example 1, an ultraviolet curable hard coating liquid (UV-1700B manufactured by Nippon Synthetic Chemical Industry Co., Ltd.) containing urethane acrylate as a curable compound is applied and irradiated with ultraviolet rays. The coating film was cured by irradiating ultraviolet rays using a lamp to form a hard coat layer (cured film) having a thickness of 4 μm. During the above process, the temperature of the resin plate was measured with an infrared radiation thermometer at any time, and the maximum temperature was about 100°C.
Table 2 shows the type of resin plate used, the main component of the coating liquid used to form the functional layer, the temperature of the resin plate in the process of forming the functional layer, and the evaluation results of the resin plate used and the liquid crystal display protective plate obtained. show.

[Comparative Examples 2 to 4] (Production and evaluation of liquid crystal display protective plate)
A liquid crystal display protective plate was manufactured in the same manner as in Comparative Example 1 except that the type of resin plate used was changed.
Table 2 shows the type of resin plate used, the main component of the coating liquid used to form the functional layer, the temperature of the resin plate in the process of forming the functional layer, and the evaluation results of the resin plate used and the liquid crystal display protective plate obtained. show.

[Comparative Examples 5 to 7] (Production and evaluation of liquid crystal display protective plate)
A protective plate for a liquid crystal display was produced in the same manner as in Example 1-1, except that the types of resin plate and function-imparting film used and the temperature of the resin plate in the bonding process were changed.
Table 2 shows the types of the resin plate and the function-imparting film used, the temperature of the resin plate in the bonding process, the evaluation results of the resin plate and the function-imparting film used, and the evaluation result of the obtained liquid crystal display protective plate.

[Summary of results]
In Reference Examples 1 to 4, resin plates (RP1) to (RP4) having an in-plane retardation value (R1) of 50 to 210 nm could be produced by adjusting the extrusion molding conditions.
In Examples 1-1, 1-2, 2-1, 2-2, and 3 to 7, the temperature of the resin plate exceeded 60°C with respect to the resin plate obtained in any of Reference Examples 1 to 4. A protective plate for a liquid crystal display having a functional layer was produced by bonding the function-imparting films under no conditions. In all of these examples, the decrease in the in-plane retardation value (Re value) of the resin plate in the bonding process is small, and all of the obtained resin plates have the in-plane retardation value of the liquid crystal display protective plate. (R2) was 50 to 210 nm. It was confirmed that all of the obtained liquid crystal display protective plates had improved pencil hardness or antireflection properties compared to before bonding the function-imparting film together, and that desired functions were imparted. All of the obtained liquid crystal display protective plates had good visibility of the liquid crystal display through a polarizing filter.

In Comparative Examples 1 to 4, a functional layer was directly formed on the resin plate obtained in any one of Reference Examples 1 to 4 without using a function-imparting film. Since it was heated to 100° C. in the functional layer forming process, the in-plane retardation value (Re value) of the resin plate greatly decreased, and all of the obtained resin plates had the in-plane retardation value (Re value) of the liquid crystal display protective plate. R2) became less than 50 nm. All of the obtained liquid crystal display protective plates had poor visibility of the liquid crystal display through a polarizing filter.

In Comparative Examples 5 to 7, the resin plate obtained in any one of Reference Examples 1 to 4 was laminated with a function-imparting film under the condition that the temperature of the resin plate exceeded 60 ° C. to form a liquid crystal display protective plate. manufactured. In all of these comparative examples, the in-plane retardation value (Re value) of the resin plate in the bonding process was greatly reduced, and all of the obtained liquid crystal display protective plates were good for viewing the liquid crystal display through a polarizing filter. was of poor quality.

The present invention is not limited to the above-described embodiments and examples, and design changes can be made as appropriate without departing from the gist of the present invention.

This application claims priority based on Japanese Patent Application No. 2017-241586 filed on December 18, 2017, and the entire disclosure thereof is incorporated herein.

1, 2 liquid crystal display protection plate 11 T die 12 first cooling roll (first cooling roll)
13 Second cooling roll (second cooling roll)
14 third cooling roll (third cooling roll)
15 Take-up rolls 16, 16X, 16Y Resin plate 17 Functionality imparting film 21 Polycarbonate resin-containing layers 22, 22A, 22B Methacrylic resin-containing layer 23 Base film 24 Functional layer

Claims (5)

A method for manufacturing a liquid crystal display protective plate, comprising the step (X) of preparing a resin plate and the step (Y) of bonding a functional imparting film to the resin plate using an adhesive or an adhesive, ,
The step (Y) is carried out under the conditions that the temperature of the resin plate is 40 to 60° C. and no active energy ray is irradiated ,
The in-plane retardation value (R1) of the resin plate is 50 to 210 nm,
The in-plane retardation value (R2) of the liquid crystal display protective plate is 50 to 210 nm,
Liquid crystal display protection, wherein the ratio (R2/R1) of the in-plane retardation value (R2) of the liquid crystal display protective plate to the in-plane retardation value (R1) of the resin plate is 0.9 to 1.1. Board manufacturing method. 2. The method of manufacturing a liquid crystal display protective plate according to claim 1, wherein said resin plate is a thermoplastic resin laminate in which a methacrylic resin-containing layer is laminated on at least one surface of a polycarbonate resin-containing layer. Step (X) is
a step of co-extrusion from a T-die in a molten state of the thermoplastic resin laminate in which the methacrylic resin-containing layer is laminated on at least one surface of the polycarbonate resin-containing layer;
While forming a bank between the first cooling roll and the second cooling roll, the molten thermoplastic resin laminate is sandwiched, and after the thermoplastic resin laminate is wound around the second cooling roll, a third cooling roll is formed. A step of cooling by wrapping around a cooling roll;
3. The method of manufacturing a liquid crystal display protective plate according to claim 2, further comprising the step of taking said thermoplastic resin laminate after cooling with a take-up roll. The function-imparting film comprises a base film and at least one functional layer laminated on the surface of the base film,
4. The method for manufacturing a liquid crystal display protective plate according to claim 1, wherein the in-plane retardation value (R3) of the base film is 10 nm or less. 5. The method of manufacturing a liquid crystal display protective plate according to claim 4, wherein the base film is made of acrylic resin or triacetyl cellulose resin.

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