JPWO2019203230A1 - Laminated sheet and its manufacturing method, and display with protective cover - Google Patents

Abstract

The present invention provides a laminated sheet having a laminated structure in which a surface layer containing a methacrylic resin is laminated on at least one surface of a base material layer containing a polycarbonate resin, and the number of die lines at the laminated interface is reduced. The laminated sheet (10X) of the present invention has a laminated structure in which a surface layer (12A, 12B) containing a methacrylic resin is laminated on at least one surface of a base material layer (11) containing a polycarbonate resin. A test sample with a width of 900 mm was visually inspected indoors with a lit three-wavelength fluorescent lamp and an illuminance of 2300 to 2600 lux. The number is 5 or less.

Description

The present invention relates to a laminated sheet, a method for manufacturing the same, and a display with a protective cover.

Flat panel displays such as liquid crystal displays and touch panel displays that combine such flat panel displays and touch panels (also called touch screens) are digital information for mobile phones (including smartphones), handheld game consoles, car navigation systems, etc. It is used in equipment. In particular, in-vehicle displays are becoming more important from the viewpoints of cockpit technology development, legal and regulatory trends, and safety as research on autonomous driving of vehicles progresses.
A transparent protective cover is preferably installed on the surface of the liquid crystal display, the touch panel, or the like in order to prevent scratches on the surface due to input operations or the like. Conventionally, tempered glass is mainly used as the material of the protective cover, but in recent years, the use of transparent resin has been increasing from the viewpoint of workability and weight reduction.

As a protective cover made of a transparent resin, Patent Document 1 discloses a laminated sheet containing a polycarbonate resin layer having excellent impact resistance and a methacrylic resin layer having high gloss and excellent scratch resistance (claim 1). .. This laminated sheet can be produced by heat melt molding, preferably coextrusion molding. In coextrusion molding, a plurality of types of molten resins discharged from a T-die in a laminated state are pressed and cooled by being sandwiched between a pair of cooling rolls (also referred to as nip rolls), and laminated with a desired thickness. It becomes a sheet.

Japanese Unexamined Patent Publication No. 2011-33751 Japanese Unexamined Patent Publication No. 2001-21268 JP-A-2017-193070

On the surface and / or the laminated interface of the laminated sheet produced by coextrusion molding, streaky defects called die lines, which are unfavorable in appearance, may be formed. When the molten resin passes over the lip land portion or the resin deteriorated product adhering to the lip land portion or the lip portion of the T die, a die line may be formed on the surface of the laminated sheet. When the molten resin passes over the deteriorated resin material adhering to the metal wall surface in the T-die, a die line may be formed at the laminating interface of the laminated sheet. Since the former die line exists on the surface of the laminated sheet, it can be erased relatively easily when it is sandwiched and pressurized by a pair of cooling rolls, but the latter die line exists at the laminated interface, so that a pair of die lines exist. Even if it is sandwiched between cooling rolls and pressurized, it cannot be easily erased. If a die line is generated at the laminated interface, it is necessary to stop the production equipment and disassemble and clean it, which increases the production cost. It is preferable that the die line, particularly the die line at the laminated interface, can be effectively suppressed.

Patent Document 2 discloses a method of using a T-die in which the R of the lip edge and the surface roughness Ra are within a specific range as a method of reducing the die line in the melt extrusion molding of the polycarbonate resin film (claim). Item 4, paragraphs 0020 to 0022). In Patent Document 2, the lip edge R portion of the T-die and the portion having a predetermined surface roughness Ra are subjected to a very precise polishing treatment as a surface finish, and further plated with chrome plating or the like to prevent corrosion. (Paragraph 0023). Although this method is effective in suppressing the die line on the sheet surface, this method alone is not sufficient for suppressing the die line at the laminated interface.

Patent Document 3 discloses a method for producing a T-die, which comprises a step of forming a layer made of a nitrogen-based intermetallic compound on an inner wall surface and a surface of a lip portion by plasma nitriding treatment (claim 1). By using the T-die produced by this method, it is possible to improve the releasability of the molten resin and the resin deteriorated product from the T-die and suppress the generation of die lines. However, this method is not effective when a relatively large amount of resin deteriorates is generated, such as at the start of production. Further, since the formation of the deteriorated resin product cannot be suppressed by this method, the deteriorated resin product produced may be mixed in the final product to form a defect of colored foreign matter.

By capturing the resin deteriorated product generated upstream of the T die by using a filtration means such as a polymer filter, it is possible to suppress the adhesion of the resin deteriorated product to the inner wall surface of the T die. However, the filtration means cannot capture the resin deteriorated product generated in the single tube downstream of the filtration means. Further, the resin deteriorated product once captured by the filtration means may change its shape due to the pressure received from the upstream and pass through the filtration means. For this reason, it is difficult to effectively reduce the die line simply by providing the filtration means.

The present invention has been made in view of the above circumstances, and has a laminated structure in which a surface layer containing a methacrylic resin is laminated on at least one surface of a base material layer containing a polycarbonate resin, and the number of die lines at the laminated interface is large. It is an object of the present invention to provide a reduced laminated sheet.
Another object of the present invention is to provide the laminated sheet in which the number of colored foreign matter defects existing per unit area is reduced.

The present invention provides the following laminated sheets [1] to [10], a method for manufacturing the same, and a display with a protective cover.
[1] A laminated sheet in which a surface layer containing a methacrylic resin is laminated on at least one surface of a base material layer containing a polycarbonate resin.
A test sample with a width of 900 mm was visually inspected indoors with a lit three-wavelength fluorescent lamp and an illuminance of 2300 to 2600 lux. Laminated sheet with 5 or less sheets.

[2] When a 500 mm square test sample is visually inspected in a room equipped with a lit three-wavelength fluorescent lamp and having an illuminance of 2300 to 2600 lux.
The number of colored foreign matter defects with a size of 0.01 mm ² or more and 0.30 ^{mm or less 2 is 50 or less.}
The laminated sheet of [1], wherein the number of defects of colored foreign matter having a size of 0.30 mm ^{2 or more is 0.}

[3] The surface layer is a laminate of [1] or [2] containing 5 to 90% by mass of a methacrylic resin and 95 to 10% by mass of a copolymer containing an aromatic vinyl compound unit and a maleic anhydride unit. Sheet.
[4] The laminated sheet of [3], wherein the copolymer contains 50 to 84% by mass of an aromatic vinyl compound unit, 15 to 49% by mass of a maleic anhydride unit, and 1 to 35% by mass of a methacrylic acid ester unit.
[5] The laminated sheet according to any one of [1] to [4], which has an in-plane retardation value of 50 to 330 nm at least in a part in the width direction.
[6] The laminated sheet according to any one of [1] to [5], which has a scratch resistant layer, an antiglare layer, or an antireflection layer on the surface layer.
[7] The laminated sheet according to any one of [1] to [6], which is used as a protective cover for a liquid crystal display or a touch panel display.
[8] A display with a protective cover including a liquid crystal display or a touch panel display and a protective cover made of the laminated sheet according to any one of [1] to [6].

[9] A step of coextruding a thermoplastic resin laminate in which the surface layer containing the methacrylic resin is laminated on at least one surface of the base material layer containing the polycarbonate resin is co-extruded from a T-die in a molten state.
As the T-die, any one of [1] to [6], wherein the inner wall surface is plated and the T-die having an arithmetic mean height (Ra) of 50 nm or less on the wall surface of the flow path for the base material layer is used. Method of manufacturing laminated sheets.
[10] A step of filtering the resin material for the base material layer in the molten state using a polymer filter before laminating the resin material for the base material layer in the molten state and the resin material for the surface layer in the molten state. Have and
Austenitic stainless steel and / or Ni-Cr-Mo alloy is selected as the material of each part of the polymer filter and the single tube disposed between the polymer filter and the T-die, [9]. Method of manufacturing laminated sheet.

According to the present invention, by devising a manufacturing method, it has a laminated structure in which a surface layer containing a methacrylic resin is laminated on at least one surface of a base material layer containing a polycarbonate resin, and the number of die lines at the laminated interface is increased. It is possible to provide a reduced laminated sheet.
According to the present invention, it is possible to provide the laminated sheet in which the number of colored foreign matter defects existing per unit area is reduced by devising the manufacturing method.

It is a schematic cross-sectional view of the laminated sheet of 1st Embodiment which concerns on this invention. It is a schematic cross-sectional view of the laminated sheet of the 2nd Embodiment which concerns on this invention. It is a schematic diagram of the manufacturing apparatus of the laminated sheet of one Embodiment which concerns on this invention.

[Laminated sheet]
The laminated sheet of the present invention has a structure in which a surface layer containing a methacrylic resin (PM) is laminated on at least one surface of a base material layer containing a polycarbonate resin (PC).
1 and 2 are schematic cross-sectional views of the laminated sheets of the first and second embodiments according to the present invention. In these figures, the same components are labeled with the same reference numerals.
The laminated sheet 10X of the first embodiment shown in FIG. 1 has a structure in which surface layers 12A and 12B containing methacrylic resin (PM) are laminated on both sides of a base material layer 11 containing a polycarbonate resin (PC), respectively. Have. The surface layer 12A and the surface layer 12B may or may not have the same composition and thickness.
The laminated sheet 10Y of the second embodiment shown in FIG. 2 has a structure in which a surface layer 12 containing a methacrylic resin (PM) is laminated on one side of a base material layer 11 containing a polycarbonate resin (PC). ..
In the laminated sheets 10X and 10Y, the thickness of each layer can be appropriately designed. The laminated sheets 10X and 10Y may have any layer other than the above.

(Base layer)
The base material layer contains one or more types of polycarbonate resin (PC). In the present specification, the polycarbonate resin is a general non-modified polycarbonate resin such as a bisphenol A type polycarbonate resin unless otherwise specified.
The polycarbonate resin (PC) is preferably obtained by copolymerizing one or more divalent phenols and one or more carbonate precursors. Examples of the divalent phenol include 2,2-bis (4-hydroxyphenyl) propane (commonly known as bisphenol A), 1,1-bis (4-hydroxyphenyl) ethane, and 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) Hydroxyphenyl) sulfone and the like can be mentioned, with bisphenol A being preferred. Examples of the carbonate precursor include carbonyl halides such as phosgene; carbonate esters such as diphenyl carbonate; and haloformates such as dihaloformates of divalent phenols.
Polycarbonate resin (PC) can be produced by an interfacial polymerization method in which an aqueous solution of divalent phenol and an organic solvent solution of a carbonate precursor are reacted at an interface, and a method in which the dihydric phenol and the carbonate precursor are heated at high temperature, reduced pressure, and none. Examples thereof include an ester exchange method in which the reaction is carried out under solvent conditions.

The weight average molecular weight (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 laminated sheet of the present invention has excellent impact resistance and heat resistance. When Mw is 100,000 or less, the polycarbonate resin (PC) is excellent in moldability, and the productivity of the laminated sheet of the present invention can be enhanced.

A commercially available product may be used as the polycarbonate resin (PC). Sumika Stylon Polycarbonate Co., Ltd. "Calibre (registered trademark)" and "SD Polyca (registered trademark)", Mitsubishi Engineering Plastics Co., Ltd. "Iupilon / Novarex (registered trademark)", Idemitsu Kosan Co., Ltd. "Taflon (registered trademark)" "Trademark)" and "Panlite (registered trademark)" manufactured by Teijin Chemicals Ltd.

The base material layer can contain one or more other polymers, if desired. The other polymer is not particularly limited, and other thermoplastic resins such as polyolefins such as polyethylene and polypropylene, polyamide, polyphenylene sulfide, polyetheretherketone, polyester, polysulfone, polyphenylene oxide, polyimide, polyetherimide, and polyacetal. ; Examples include thermosetting resins such as phenol resin, melamine resin, silicone resin, and epoxy resin. The content of the other polymer in the base material layer is preferably 10% by mass or less, more preferably 5% by mass or less, and particularly preferably 2% by mass or less.

The base material layer can contain various additives, if necessary. Additives include antioxidants, heat deterioration inhibitors, UV absorbers, light stabilizers, lubricants, mold release agents, polymer processing aids, antistatic agents, flame retardants, dyes / pigments, light diffusers, and luster. Examples thereof include impact resistant modifiers such as erasers, core-shell particles and block copolymers, and phosphors. The content of the additive can be appropriately set as long as the effect of the present invention is not impaired. 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 content of the light stabilizer is 100 parts by mass with respect to 100 parts by mass of the constituent resin of the base material layer. The amount is preferably 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 another polymer and / or additive is added to the base material layer, the timing of addition may be during or after the polymerization of the polycarbonate resin (PC).

From the viewpoint of stability of heat melt molding, the melt flow rate (MFR) of the constituent resin of the base material layer containing one or more kinds of polycarbonate resins (PC) is preferably 1 to 30 g / 10 minutes, more preferably 3 to 3 to 30 g. 20 g / 10 minutes, particularly preferably 5-10 g / 10 minutes. In the present specification, the MFR of the constituent resin of the base material layer is a value measured using a melt indexer under the conditions of a temperature of 300 ° C. and a load of 1.2 kg, unless otherwise specified.

(Surface layer)
The surface layer is a methacrylic resin-containing layer containing one or more types of methacrylic resin (PM). Methacrylic resin (PM) is a resin having excellent gloss, transparency, surface hardness and the like. The content of the methacrylic resin (PM) in the surface layer is preferably 20 to 100% by mass.
From the viewpoint of stability of heat melt molding, the melt flow rate (MFR) of the constituent resin of the methacrylic resin-containing layer containing one or more methacrylic resins (PM) is preferably 1 to 10 g / 10 minutes, more preferably 1. .5 to 7 g / 10 minutes, particularly preferably 2 to 4 g / 10 minutes. In the present specification, the MFR of the constituent resin of the methacrylic resin-containing layer is a value measured using a melt indexer at a temperature of 230 ° C. under a load of 3.8 kg, unless otherwise specified.

As a preferable methacrylic resin-containing layer as a surface layer, a methacrylic resin-containing layer made of one or more methacrylic resins (PM) and a methacrylic resin (composition) that can contain one or more other polymers if necessary. (MLA); from a methacrylic resin composition (MR1) containing a methacrylic resin (PM) and a SMA resin (S) (details will be described later), which may further contain one or more other polymers as needed. Methacrylate resin-containing layer (MLB); methacrylic resin (PM) and multilayer structure rubber particles (RP) (details will be described later), and can further contain one or more other polymers if necessary. Examples thereof include a methacrylic resin-containing layer (MLC) made of a resin composition (MR2).

<Methacrylic resin (PM)>
The methacrylic acid resin (PM) contained in the methacrylic acid resin-containing layers (MLA) to (MLC) is preferably one or more methacrylic acid hydrocarbon esters containing methyl methacrylate (MMA) (hereinafter, also simply referred to as methacrylic acid ester). It is a homopolymer or a copolymer containing a structural unit derived from. The hydrocarbon group in the methacrylic acid ester may be a non-cyclic aliphatic hydrocarbon group such as a methyl group, an ethyl group and a propyl group, an alicyclic hydrocarbon group, or an aromatic group such as a phenyl group. It may be a hydrocarbon group. From the viewpoint of transparency, the content of the methacrylic acid ester monomer unit in the methacrylic acid 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.

The methacrylic resin (PM) may contain structural units derived from one or more other monomers other than the methacrylic acid ester. Other monomers include methyl acrylate (MA), ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl acrylate, hexyl acrylate, acrylic. 2-Ethylhexyl acrylate, Nonyl acrylate, Decyl acrylate, Dodecyl acrylate, Stearyl acrylate, 2-Hydroxyethyl acrylate, 2-Hydroxypropyl acrylate, 4-Hydroxybutyl acrylate, Cyclohexyl acrylate, 2-2-Acrylic acid Methoxyethyl, 3-methoxybutyl acrylate, trifluoromethyl acrylate, trifluoroethyl acrylate, pentafluoroethyl acrylate, glycidyl acrylate, allyl acrylate, phenyl acrylate, toluyl acrylate, benzyl acrylate, acrylate Examples thereof include isobornyl and acrylic acid esters such as 3-dimethylaminoethyl acrylate. Among them, MA, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, tert-butyl acrylate and the like are preferable, and MA and ethyl acrylate and the like are preferable from the viewpoint of availability. Is more preferable, and MA is particularly preferable. The content of the structural unit derived from other monomers in the methacrylic resin (PM) 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 (PM) is preferably obtained by polymerizing one or more methacrylic acid esters containing MMA and, if necessary, other monomers. When a plurality of types of monomers are used, usually, a plurality of types of monomers are mixed to prepare a monomer mixture, and then polymerization is performed. The polymerization method is not particularly limited, and from the viewpoint of productivity, a radical polymerization method such as a massive polymerization method, a suspension polymerization method, a solution polymerization method, and an emulsion polymerization method is preferable.

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

<Methyl resin composition (MR1)>
The methacrylic resin composition (MR1) contains the above-mentioned methacrylic resin (PM) and SMA resin (S), and can further and optionally contain one or more other polymers. The content of the methacrylic resin (PM) in the resin composition (MR1) is preferably 5 to 80% by mass, more preferably 5 to 55% by mass, and particularly preferably 10 to 50% by mass. The content of the SMA resin (S) in the resin composition (MR1) is preferably 95 to 20% by mass, more preferably 95 to 45% by mass, and particularly preferably 90 to 50% by mass. When the content of these resins is within the above range, the heat resistance of the surface layer is improved, and in the step of forming the cured film, when the laminated sheet is heated, the surface condition of the laminated sheet is suppressed from being roughened. be able to. Further, the glass transition temperature difference from the polycarbonate resin (PC) used for the base material layer can be reduced, and the warp of the laminated sheet in sheet molding can be reduced.

As used herein, the SMA resin (S) is a copolymer containing a structural unit derived from one or more aromatic vinyl compounds and one or more acid anhydrides containing maleic anhydride (MAH). Aromatic vinyl compounds include styrene (St); nuclear 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; Of these, styrene (St) is preferable from the viewpoint of availability. From the viewpoint of transparency and moisture resistance of the resin composition (MR1), the content of the aromatic vinyl compound monomer unit in the SMA resin (S) is preferably 50 to 85% by mass, more preferably 55 to 82. It is by mass, particularly preferably 60 to 80% by mass. As the acid anhydride, at least maleic anhydride (MAH) is used from the viewpoint of availability, and if necessary, other acid anhydrides such as citraconic anhydride and dimethyl maleic anhydride can be used. From the viewpoint of transparency and heat resistance of the resin composition (MR1), the content of the acid anhydride monomer unit in the SMA resin (S) is preferably 15 to 50% by mass, more preferably 18 to 45% by mass. %, Especially preferably 20 to 40% by mass.

The SMA resin (S) can contain structural units derived from one or more methacrylic acid ester monomers in addition to aromatic vinyl compounds and acid anhydrides. Examples of the methacrylic acid ester include MMA, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, and cyclohexyl methacrylate. Examples thereof include phenyl methacrylate, benzyl methacrylate, 1-phenylethyl methacrylate and the like. Of these, methacrylic acid alkyl esters and the like having an alkyl group having 1 to 7 carbon atoms are preferable. MMA is particularly preferable from the viewpoint of heat resistance and transparency of the SMA resin (S). From the viewpoint of bendability and transparency of the laminated sheet, the content of the methacrylic acid ester monomer unit in the SMA resin (S) is preferably 1 to 35% by mass, more preferably 3 to 30% by mass, particularly. It is preferably 5 to 26% by mass. In this case, the content of the aromatic vinyl compound monomer unit is preferably 50 to 84% by mass, and the content of the acid anhydride monomer unit is preferably 15 to 49% by mass.

The SMA resin (S) may have structural units derived from other monomers other than aromatic vinyl compounds, acid anhydrides, and methacrylic acid esters. As the other monomer, those described above can be used in the description of the methacrylic resin (PM). The content of the other monomer unit 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, a methacrylic acid ester if necessary, and another monomer if necessary. In this polymerization, usually, a plurality of kinds of monomers are mixed to prepare a monomer mixture, and then the polymerization is carried out. The polymerization method is not particularly limited, and a radical polymerization method such as a massive polymerization method and a solution polymerization method is preferable from the viewpoint of productivity.

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

The resin composition (MR1) is obtained by mixing a methacrylic resin (PM), a SMA resin (S), and, if necessary, another polymer. Examples of the mixing method include a melt mixing method and a solution mixing method. In the melt mixing method, a single-screw or multi-screw kneader; an open roll, a Banbury mixer, a melt kneader such as a kneader, or the like is used, and if necessary, an inert gas such as nitrogen gas, argon gas, or helium gas is used. Melting and kneading can be performed in an atmosphere. In the solution mixing method, the methacrylic resin (PM) and the SMA resin (S) can be dissolved in an organic solvent such as toluene, tetrahydrofuran, and methyl ethyl ketone and mixed.

<Methyl resin composition (MR2)>
The methacrylic resin composition (MR2) contains the above-mentioned methacrylic resin (PM) and multi-layered rubber particles (RP), and can further contain one or more other polymers if necessary. The content of the methacrylic resin (PM) in the resin composition (MR2) is preferably 80 to 99% by mass, more preferably 85 to 95% by mass. The content of the multilayer structure rubber particles (RP) in the resin composition (MR2) is preferably 20 to 1% by mass, more preferably 15 to 5% by mass. Since the surface layer contains the multi-layered rubber particles (RP), the crack resistance of the laminated sheet can be improved. If the content of the multi-layered rubber particles (RP) is too small, cracks may occur at the edges depending on the conditions during punching. On the other hand, if the content of the multilayer structure rubber particles is excessive, the laminated sheet will be whitened during molding and bending, the surface hardness of the surface layer will be lowered and easily scratched, and the appearance of the product after shape transfer will be poor. There is a risk of becoming.

In the present specification, the multilayer structure rubber particles (RP) are acrylic multilayer structure rubber particles. Examples of the multilayer rubber particles (RP) include acrylic multilayer rubber particles having one or more graft copolymer layers containing one or more acrylic acid alkyl ester copolymers. As the acrylic multilayer structure rubber particles, those disclosed in JP-A-2004-352837 can be used. The acrylic multilayer structure rubber particles can preferably have a crosslinked polymer layer containing an acrylic acid alkyl ester unit having 6 to 12 carbon atoms.
The number of layers of the multilayer structure rubber particles (RP) is not particularly limited, and may be two layers or three or more layers. Preferably, the multilayer rubber particles (RP) are three or more core-shell multilayer particles including an innermost layer (RP-a), one or more intermediate layers (RP-b), and an outermost layer (RP-c). Is.

The constituent polymer of the innermost layer (RP-a) contains an MMA unit and a graftable or crosslinkable monomer unit, and can further contain one or more other monomer units, if necessary. The content of MMA units in the constituent polymer of the innermost layer (RP-a) is preferably 80 to 99.99% by mass, more preferably 85 to 99% by mass, and particularly preferably 90 to 98% by mass. The ratio of the innermost layer (RP-a) in the three or more layers of multilayer structure particles (RP) is preferably 0 to 15% by mass, and more preferably 7 to 13% by mass. When the ratio of the innermost layer (RP-a) is within such a range, the heat resistance of the surface layer can be enhanced.

The constituent polymer of the intermediate layer (RP-b) contains an acrylic acid alkyl ester unit having 6 to 12 carbon atoms and a graftable or crosslinkable monomer unit, and if necessary, one or more other simple polymers. It can include meter units. The content of the acrylic acid alkyl ester unit in the constituent polymer of the intermediate layer (RP-b) is preferably 70 to 99.8% by mass, more preferably 75 to 90% by mass, and particularly preferably 78 to 86% by mass. Is. The ratio of the intermediate layer (RP-b) in the three or more layers of the multilayer structure rubber particles (RP) is preferably 40 to 60% by mass, more preferably 45 to 55% by mass. When the ratio of the intermediate layer (RP-b) is within such a range, the surface hardness of the surface layer can be increased and the surface layer can be made hard to crack.

The constituent polymer of the outermost layer (RP-c) contains MMA units and, if necessary, one or more other monomer units. The content of MMA units in the constituent polymer of the outermost layer (RP-c) is preferably 80 to 100% by mass, more preferably 85 to 100% by mass, and particularly preferably 90 to 100% by mass. The ratio of the outermost layer (RP-c) in the three or more layers of multilayer structure particles (RP) is preferably 35 to 50% by mass, and more preferably 37 to 45% by mass. When the ratio of the outermost layer (RP-c) is within such a range, the surface hardness of the surface layer can be increased and the surface layer can be made hard to crack.

The particle size of the multi-layered rubber particles (RP) is preferably 0.05 to 0.3 μm. The particle size can be measured by a known method such as electron microscope observation and dynamic light scattering measurement. For measurement by electron microscope observation, for example, a specific layer of multilayer structure rubber particles (RP) is selectively stained by an electron staining method, and a plurality of layers are selectively stained using a transmission electron microscope (TEM) or a scanning electron microscope (SEM). This can be done by actually measuring the particle size of the particles and finding the average value thereof. The dynamic light scattering method is a measurement method that utilizes the principle that the Brownian motion of a particle increases as the particle size increases.

The multi-layered rubber particles (RP) are made of multi-layered rubber particles (RP) in order to suppress a decrease in handleability due to sticking between the multi-layered rubber particles (RP) and a decrease in impact resistance due to poor dispersion during melt kneading. ) And particles (D) for dispersion can be used in the form of latex or powder. For example, the dispersion particles (D) are made of a (co) polymer of one or more types of monomers mainly composed of MMA, and particles having a particle size relatively smaller than that of the multilayer rubber particles (RP) are used. Can be done.

The particle size of the dispersion particles (D) is preferably as small as possible from the viewpoint of improving dispersibility, and is preferably 40 to 120 nm, more preferably 50 to 100 nm from the viewpoint of production reproducibility by the emulsion polymerization method. The amount of the dispersion particles (D) added is preferably 10 to 50% by mass, more preferably 10 to 50% by mass, based on the total amount of the multilayer structure rubber particles (RP) and the dispersion particles (D) from the viewpoint of the effect of improving dispersibility. It is preferably 20 to 40% by mass.

The methacrylic resin-containing layers (MLA) to (MLC) can contain one or more other polymers, if necessary. The other polymer is not particularly limited, and the same polymer as described above can be used in the description of the base material layer. The content of the other polymer in the methacrylic resin-containing layers (MLA) to (MLC) 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 layers (MLA) to (MLC) can contain various additives, if necessary. As the additive, the same additive as described above can be used in the description of the base material layer. The content of the additive can be appropriately set as long as the effect of the present invention is not impaired. For example, the content of the antioxidant is 0.01 to 1 part by mass and the content of the ultraviolet absorber is 0.01 to 3 parts by mass with respect to 100 parts by mass of the constituent resins of the methacrylic resin-containing layers (MLA) to (MLC). The content of the light stabilizer is preferably 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 the methacrylic resin-containing layers (MLA) to (MLC) contain other polymers and / or additives, the timing of addition is methacrylic resin (PM), SMA resin (S), and multilayer rubber particles (RP). It may be at the time of polymerization of the resin such as, or at the time of mixing or after mixing a plurality of kinds of resins including methacrylic resin (PM).

<Total thickness of laminated sheet, thickness of surface layer>
The total thickness (TT) and the thickness (ST) of the surface layer of the laminated sheet of the present invention are appropriately designed according to the application of the laminated sheet and the required performance for the laminated sheet.
The total thickness (TT) of the laminated sheet of the present invention is preferably 0.5 to 6.0 mm, more preferably 1.0 to 5.0 mm, and particularly preferably 1.0 to 4.0 mm. When the TT is within the above range, distortion and bleeding of an image during screen operation of a touch panel display using the laminated sheet of the present invention as a protective cover are suppressed.
The thickness (ST) of the surface layer is preferably 0.03 to 0.40 mm, more preferably 0.05 to 0.30 mm, and particularly preferably 0.06 to 0.30 mm. In the case of a laminated sheet in which surface layers are laminated on both sides of the base material layer, ST is the total thickness of the two surface layers. When the ST is within the above range, the laminated sheet of the present invention has sufficient rigidity, the laminated sheet of the present invention has excellent punching workability, and the screen of the touch panel display using the laminated sheet of the present invention as a protective cover. Image distortion and blurring during operation are suppressed.

<Other resin layers>
The laminated sheet of the present invention may have another resin layer as long as the surface layer is laminated on at least one surface of the base material layer.
The laminated sheet of the present invention can have a cured film on the surface layer, if necessary. The cured coating can function as a scratch resistant layer or a low reflective layer for the effect of improving visibility. The cured film can be formed by a known method (see JP-A-2004-299199, JP-A-2006-103169, etc.). The thickness of the scratch resistant (hard coat property) cured film (scratch resistant layer, hard coat layer) is preferably 2 to 30 μm, more preferably 5 to 20 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. The thickness of the low-reflection cured film (low-reflection layer) is preferably 80 to 200 nm, more preferably 100 to 150 nm. If it is too thin or too thick, the low reflection performance may be insufficient.
The laminated sheet of the present invention may have a known anti-glare (anti-glare) layer and / or anti-reflection (anti-reflection) layer on the surface layer, if necessary.

[Manufacturing method of laminated sheet]
Hereinafter, preferred embodiments of the method for producing a laminated sheet of the present invention will be described. The laminated sheet of the present invention can be produced by a known method, and is preferably produced by a production method including coextrusion molding.

The structure of the laminated sheet manufacturing apparatus of one embodiment according to the present invention will be described with reference to the drawings.
The manufacturing apparatus 30 shown in FIG. 3 includes an extruder 31 for a base material layer, a metering pump 33 for the base material layer, and a filtration means 34 for the base material layer, which are connected via a single tube 32 for the base material layer. The resin material for the base material layer is melt-plasticized using the base material layer extruder 31 and extruded into the base material layer single tube 32. The molten resin material for the base material layer extruded into the single pipe for the base material layer 32 is sent downstream using a metering pump 33 such as a gear pump. A filtration means 34 for a base material layer such as a polymer filter is arranged in the subsequent stage of the metering pump 33, and resin deteriorated substances and other foreign substances are removed before laminating.
The manufacturing apparatus 30 also includes a surface layer extruder 41, a surface layer metering pump 43, and a surface layer filtration means 44, which are connected via a single surface layer tube 42. The surface layer resin material is melt-plasticized using the surface layer extruder 41 and extruded into the surface layer single tube 42. The molten surface layer resin material extruded into the surface layer single tube 42 is sent downstream using a metering pump 43 such as a gear pump. A filtration means 44 for a surface layer such as a polymer filter is arranged in the subsequent stage of the metering pump 43, and resin deteriorated substances and other foreign substances are removed before laminating.

The manufacturing apparatus 30 also includes a T-die 51, a plurality of cooling rolls (first to third cooling rolls 52 to 54 in the illustrated example), and a pair of pick-up rolls 55.
The resin material for the base material layer in the molten state after passing through the filtration means for the base material layer 34 and the resin material for the surface layer in the molten state after passing through the filtration means for the surface layer 44 are at least one surface of the base material layer. In the form of a thermoplastic resin laminate in which a surface layer is laminated on the surface layer, it is co-extruded from a T-die 51 having a wide discharge port in a molten state. Examples of the laminating method include a feed block method of laminating before the inflow of the T-die, a multi-manifold method of laminating inside the T-die, and the like. The multi-manifold method is preferable from the viewpoint of improving the interfacial smoothness between the layers of the laminated sheet.

The molten thermoplastic resin laminate co-extruded from the T-die 51 is pressurized and cooled by using a plurality of cooling rolls (first to third cooling rolls 52 to 54 in the illustrated example). The number of cooling rolls can be appropriately designed.
Examples of the cooling roll include a metal roll and an elastic roll having a metal thin film on the outer peripheral portion (hereinafter, also referred to as a metal elastic roll). Examples of the metal roll include a drilled roll and a spiral roll. The surface of the metal roll may be a mirror surface, or may have a pattern, unevenness, or the like. The metal elastic roll is composed 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 sealed between the shaft roll and the metal thin film. , Elasticity can be exhibited by the presence of fluid. The thickness of the metal thin film is preferably about 2 to 5 mm. The metal thin film preferably has flexibility, flexibility, and the like, and preferably has a seamless structure without weld joints. A metal elastic roll provided with such a metal thin film has excellent durability, and if the metal thin film is mirror-finished, it can be handled in the same manner as a normal mirror-finished roll, and a pattern, unevenness, etc. can be imparted to the metal thin film. It is easy to use because it becomes a roll that can transfer the shape of the film.

The laminated sheet 56 obtained after cooling is picked up by a pair of pick-up rolls 55. The above coextrusion, cooling, and take-back steps are carried out continuously. In this specification, a material in a heat-melted state is mainly referred to as a "thermoplastic resin laminate", and a solidified material is referred to as a "laminated sheet", but there is no clear boundary between the two. ..
The configuration of the manufacturing apparatus can be appropriately redesigned as long as it does not deviate from the gist of the present invention.

As described in the section [Problems to be Solved by the Invention], in the conventional coextrusion molding, streaky defects called die lines, which are unfavorable in appearance, are formed on the surface and / or the laminated interface of the laminated sheet to be manufactured. May be done. When the molten thermoplastic resin laminate passes over the lip land portion of the T-die or the resin deteriorated product adhering to the lip portion, a die line may be formed on the surface of the laminated sheet. The molten base material layer resin passes over the metal wall surface of the base material layer flow path in the T-die or the resin deteriorated product adhering to the confluence where the base material layer flow path and the surface layer flow path meet. If this is the case, a die line may be formed at the laminated interface of the laminated sheet. The former die line can be erased relatively easily when it is sandwiched and pressurized by a pair of cooling rolls, but the latter die line can be easily erased even when it is sandwiched and pressurized by a pair of cooling rolls. Can not. If a die line is generated at the laminated interface, it is necessary to stop the production equipment and disassemble and clean it, which increases the production cost. It is preferable that the die line, particularly the die line at the laminated interface, can be effectively suppressed.
In the conventional coextrusion molding, a resin deteriorated product generated downstream of a filtration means such as a polymer filter, or a filtration means that is once captured by a filtration means such as a polymer filter but changes its shape depending on the pressure received from the upstream. Deteriorated resin that has slipped through the filter may be mixed into the final product and form a defect of colored foreign matter.
In the present invention, the generation of die lines can be suppressed by devising the manufacturing method. In the present invention, the occurrence of defects of colored foreign matter can be suppressed by devising the manufacturing method.

(Material of polymer filter)
It is preferable that the resin material for the base material layer in the molten state and the resin material for the surface layer in the molten state are each filtered by a filtration means such as a filter before laminating. By capturing the resin deterioration products and other foreign substances contained in each molten resin material with a filter and then performing multi-layer molding, it is possible to prevent the resin deterioration products from adhering to the metal wall surface inside the T die and the lip portion of the T die. However, the generation of die lines can be suppressed.
As the filter, a polymer filter is preferable. The polymer filter can include a tubular core portion with one end closed and the other end open, a filter portion attached around the tubular core portion, and a housing for accommodating them. The location where the polymer filter is installed may be between the extruder and the T-die, and is preferably between the metering pump such as a gear pump and the T-die. The filtration accuracy of the filter is not particularly limited, and is preferably 30 μm or less, more preferably 15 μm or less, and particularly preferably 5 μm or less.

The polymer filter can capture the resin deteriorated product generated on the upstream side thereof. However, in the vicinity of the polymer filter, the residence time of the resin is relatively longer than in other portions, so that new resin deterioration may occur. Resin deterioration tends to occur more easily in the resin material for the base material layer containing the polycarbonate resin.
Of the polymer filter for the base material layer and the polymer filter for the surface layer, at least each part (core part, filter part, and housing part) of the polymer filter for the base material layer is made of austenitic stainless steel and / or Ni-Cr-. It is preferable to select a Mo alloy. Specific examples of such materials include SUS304, SUS304L, SUS316, SUS316L, SUS309S, SUS310S, SUS317, SUS317L, Hastelloy C, Hastelloy C-276, Hastelloy C-22, Hastelloy X and the like. These can be used alone or in combination of two or more. By using at least the above material as the material of each part of the polymer filter for the base material layer, the residence time of the molten resin in the polymer filter can be shortened and the deterioration of the resin can be effectively suppressed, and as a result, the die line can be used. And the occurrence of colored foreign matter defects can be effectively suppressed.

<Material of single tube>
Of the single tube for the base material layer and the single tube for the surface layer, it is preferable to select at least austenitic stainless steel and / or a Ni—Cr—Mo alloy as the material of the single tube for the base material layer. Specific examples of such materials are the same as described above. By using at least the above material as the material of the single tube for the base material layer, the residence time of the molten resin on the inner wall surface of the single tube where the flow velocity of the molten resin is theoretically zero is shortened, and the deterioration of the resin is effectively suppressed. As a result, the occurrence of die lines and colored foreign matter defects can be effectively suppressed.
Deteriorated resin produced in a single tube downstream of the polymer filter cannot be captured by the polymer filter. Therefore, in particular, for the single tube on the downstream side of the polymer filter into which the resin material for the base material layer flows, selecting the above material that can effectively suppress resin deterioration is useful for suppressing the defects of die lines and colored foreign substances. ..

<T-die plating and surface roughness Ra of the wall surface of the flow path for the base material layer>
The inner wall surface of the T-die is preferably plated. The type of plating is not particularly limited, and hard chrome plating, tungsten carbide plating and the like are preferable. The surface roughness Ra of the wall surface of the flow path for the base material layer in the plated T-die is preferably 50 nm or less, more preferably 25 nm or less, and particularly preferably 10 nm or less. In such an embodiment, it is possible to effectively suppress the adhesion of the resin deteriorated matter to the wall surface of the base material layer flow path in the T die and the confluence portion where the base material layer flow path and the surface layer flow path meet. As a result, the occurrence of die lines and colored foreign matter defects can be effectively suppressed.
In the present specification, unless otherwise specified, "surface roughness Ra" means an arithmetic mean height.

<Manufacturing equipment startup method 1>
As described above, resin deterioration tends to occur more easily in the resin material for the base material layer containing the polycarbonate resin.
When the manufacturing equipment (coextrusion molding equipment) is started up, the flow path is filled with air, so resin deterioration due to oxidation is relatively likely to occur. In order to suppress resin deterioration due to oxidation, the material for the base material layer contains a polycarbonate resin for operation start-up to which a higher concentration of antioxidant than the polycarbonate resin-containing material for actual products is added at the time of start-up operation. Materials can be used. The concentration of the antioxidant in the base material for the actual product is preferably 0.005 to 0.1% by mass. On the other hand, the concentration of the antioxidant in the base material layer material for starting operation is preferably 0.05 to 3.00% by mass, more preferably 0.10 to 2.00% by mass, and particularly preferably. Is 0.50 to 1.00% by mass.
As the antioxidant, phenol-based, phosphorus-based, and sulfur-based agents are preferable, and it is more preferable to use phenol-based and phosphorus-based agents in combination. In such an embodiment, oxidative deterioration of the polycarbonate resin (PC) at the time of starting operation can be effectively suppressed, and the occurrence of defects of die lines and colored foreign substances can be effectively suppressed.

Examples of the phenolic antioxidant include 1,1-bis (5-tert-butyl-2-methyl-4-hydroxyphenyl) butane and 1,1,3-tris (5-tert-butyl-2-methyl-4). -Hydroxyphenyl) butane, octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, pentaerythrityl-tetrakis (3- (3,5-di-tert-butyl-4-hydroxy) Phenyl) propionate), 2,2-thio-diethylenebis (3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate), 3,9-bis (2- (3- (3-tert) -Butyl-4-hydroxy-5-methylphenyl) -propionyloxy) -1,1-dimethylethyl) -2,4,8,10-tetraoxaspiro [5.5] undecane, 1,3,5-trimethyl -2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, tris (3,5-di-tert-butyl-4-hydroxybenzyl) -isocyanurate, triethylene Glycol-bis (3- (3-tert-butyl-5-methyl-4-hydroxyphenyl) propionate), 1,6-hexanediol-bis (3- (3,5-di-tert-butyl-4-hydroxy) Phenyl) propionate), 2,4-bis (n-octylthio) -6- (4-hydroxy-3,5-di-tert-butylanilino) -1,3,5-triazine, N, N'-hexamethylenebis (3,5-di-tert-butyl-4-hydroxy-hydrocinnamamide), N, N'-bis (3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyl) hydrazine, 2,2'-thiobis (4-methyl-6-tert-butylphenol), 3,5-di-tert-butyl-4-hydroxybenzylphosphonate-diethyl ester, 4,4'-thiobis (3-methyl- 6-tert-butylphenol), 4,4'-thiobis (2-methyl-6-tert-butylphenol), 2,2'-methylenebis (4-methyl-6-tert-butylphenol), and 2,2'-ethylidene. Examples include bis (4,6-di-tert-butylphenol). These can be used alone or in combination of two or more.

Phenyl antioxidants include triphenylphosphite, tris (nonylphenyl) phosphite, dilaurylhydrogenphosphite, triethylphosphite, tridecylphosphite, tris (2-ethylhexyl) phosphite, tris (tridecyl). Phenylphosphite, tristearyl phosphite, diphenylmonodecylphosphite, monophenyldidecylphosphite, diphenylmono (tridecyl) phosphite, tetraphenyldipropylene glycol diphosphite, tetraphenyltetra (tridecyl) pentaerythritol tetraphosphite, Hydrogenated bisphenol A phenol phosphite polymer, diphenylhydrogen phosphite, 4,4'-butylidene-bis (3-methyl-6-tert-butylphenyldi (tridecyl) phosphite), tetra (tridecyl) 4,4' -Isopropyridene diphenyl diphosphite, bis (tridecyl) pentaerythritol diphosphite, bis (nonylphenyl) pentaerythritol diphosphite, dilauryl pentaerythritol diphosphite, distearyl pentaerythritol diphosphite, tris (4-tert) -Butylphenyl) phosphite, tris (2,4-di-tert-butylphenyl) phosphite, hydrogenated bisphenol A pentaerythritol phosphite polymer, tetrakis (2,4-di-tert-butylphenyl) 4,4' -Biphenylene phosphonite, bis (2,4-di-tert-butylphenyl) pentaerythritol diphosphite, bis (2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphite, 2, 2'-Methylenebis (4,6-di-tert-butylphenyl) octyl phosphate, ethyl diethylphosphonoacetate, methyl acid phosphate, ethyl acid phosphate, propyl acid phosphate, isopropyl acid phosphate, butyl acid phosphate, butoxyethyl acid phosphate , Octyl acid phosphate, 2-ethylhexyl acid phosphate, decyl acid phosphate, lauryl acid phosphate, stearyl acid phosphate, oleyl acid phosphate, behenyl acid phosphate, phenyl acid phosphate, nonylphenyl acid phosphate. Phenyl acid phosphate, phenoxyethyl acid phosphate, alkoxy polyethylene glycol acid phosphate, bisphenol A acid phosphate, dimethyl acid phosphate, diethyl acid phosphate, dipropyl acid phosphate, diisopropyl acid phosphate, dibutyl acid phosphate, dioctyl acid phosphate, di-. Examples thereof include 2-ethylhexyl acid phosphate, dilauryl acid phosphate, distearyl acid phosphate, diphenyl acid phosphate, bisnonylphenyl acid phosphate, hexamethylphosphoric triamide and the like. These can be used alone or in combination of two or more.

Examples of sulfur-based antioxidants include didodecyl-3,3'-thiodipropionate, ditetradecyl-3,3'-thiodipropionate, dioctadecyl-3,3'-thiodipropionate, and ditridecyl-3,3. '-Thiodipropionate, pentaerythrityl tetrakis (3-dodecylthiopropionate), pentaerythrityl tetrakis (3-tetradecylthiopropionate), pentaerythrityl tetrakis (3-tridecylthiopropionate) And so on. These can be used alone or in combination of two or more.

<Start-up method 2 of manufacturing equipment>
As described above, resin deterioration tends to occur more easily in the resin material for the base material layer containing the polycarbonate resin.
Reducing the residence time of the resin is effective in suppressing the deterioration of the resin and the generation of die lines in order to suppress the deterioration of the resin due to oxidation at the start-up of the operation of the manufacturing apparatus (coextrusion molding equipment). As the material for the base material layer, a polycarbonate resin-containing material for operation start-up having a lower viscosity than the polycarbonate resin-containing material for actual products can be used at the time of start-up operation. The MFR of the resin material for the base material layer at the time of starting operation is preferably 10 to 30 g / 10 minutes, more preferably 10 to 20 g / 10 minutes. In such an embodiment, the residence time of the polycarbonate resin (PC) can be shortened at the start of operation to effectively suppress the oxidative deterioration of the resin, and as a result, the occurrence of die lines and colored foreign matter defects can be effectively suppressed. be able to.

Optimizing the material of each part of the polymer filter and / or the single tube, optimizing the surface roughness Ra of the wall surface of the flow path for the base material layer by plating the T-die, and resin material for the base material layer used at the start of operation. By optimizing at least one of the high-concentration addition of the antioxidant and the low viscosity of the resin material for the base material layer used at the start-up of operation, it is possible to effectively suppress the occurrence of defects of die lines and colored foreign substances. it can. The larger the number of adaptations, the higher the quality of laminated sheets with less defects of die lines and colored foreign substances can be produced.
Among the above, since the contribution to the reduction of the die line at the laminated interface is large, as the T-die, the T-die in which the inner wall surface is plated and the surface roughness Ra of the wall surface of the flow path for the base material layer is 50 nm or less is used. It is preferable to use it.
Further, since the contribution to the reduction of the defects of colored foreign substances is large, at least each part of the polymer filter for the base material layer and the single tube for the base material layer disposed between the polymer filter for the base material layer and the T die. As the material of, it is preferable to select austenitic stainless steel and / or Ni—Cr—Mo alloy.

According to the present invention, when a test sample having a width of 900 mm is visually inspected in a room equipped with a lit three-wavelength fluorescent lamp and having an illuminance of 2300 to 2600 lux, the width of 0 existing at the laminated interface is 0. It is possible to provide a laminated sheet in which the number of die lines of .3 mm or more is 5 or less.
^{According to the present invention, a 500 mm square test sample is 0.01 mm 2} or more and 0 or more when a visual inspection is performed in a room equipped with a lit three-wavelength fluorescent lamp and an illuminance of 2300 to 2600 lux. .30mm number of colored foreign drawbacks of less than ² in size is 50 or less, it is possible to provide a laminated sheet number of colored foreign drawback of 0.30 mm ² or more size is zero.

<Re value>
"Letteration (Re)" is the phase difference between the light in the direction of the main chain of the molecule and the light in the direction perpendicular to it. Generally, a polymer can be obtained by heating and melting to obtain an arbitrary shape, but it is known that the molecules are oriented by the stress generated in the process of heating and cooling to generate retardation. Therefore, in order to control the retardation, it is necessary to control the orientation of the molecule. The orientation of the molecules is generated, for example, by the stress during molding near the glass transition temperature of the polymer. In addition, in this specification, "letteration" means in-plane lettering unless otherwise specified.

By optimizing the manufacturing conditions in the extrusion molding process, the orientation of the molecules can be controlled, whereby the Re value after molding of the laminated sheet can be optimized. In the use of a protective cover for a liquid crystal display or a touch panel display, the laminated sheet of the present invention preferably has a Re value of at least a part (at least a part in the width direction in the case of extrusion molding) of 50 to 330 nm.

A cured film can be formed on at least one surface (preferably the surface of the surface layer) of the laminated sheet obtained after coextrusion molding by a known method, if necessary.
A preferably liquid curable composition containing a thermosetting compound or an active energy ray-curable compound is applied to the surface of the laminated sheet obtained after coextrusion, and the coating film is cured by heating or irradiation with active energy rays. By doing so, a cured film can be formed. The 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 and ultraviolet rays. Examples of the thermosetting composition include a polyorganosiloxane type and a crosslinked acrylic type. Examples of the active energy ray-curable composition include those containing a curable compound such as a monofunctional or polyfunctional acrylate-based monomer or oligomer and a photopolymerization initiator. The cured film can be formed by using a commercially available hard coating agent.
Anti-glare (anti-glare) and / or anti-reflection (anti-reflection) layers are formed on at least one surface (preferably the surface of the surface layer) of the laminated sheet obtained after coextrusion by a known method, if necessary. You may.

According to the present invention, there is provided a laminated sheet having a laminated structure in which a surface layer containing a methacrylic resin is laminated on at least one surface of a base material layer containing a polycarbonate resin, and the number of die lines at a laminated interface is reduced. be able to.
According to the present invention, it is also possible to provide the laminated sheet in which the number of colored foreign matter defects existing per unit area is reduced.

[Use]
The laminated sheet of the present invention is, for example, an ATM of a financial institution such as a bank; a vending machine; a television; a mobile information terminal (PDA) such as a mobile phone (including a smartphone), a personal computer, a tablet-type personal computer, a digital audio player, and the like. It is suitable as a protective cover for a liquid crystal display or a touch panel display used in digital information devices such as portable game machines, copy machines, fax machines, and car navigation systems.

Examples and comparative examples according to the present invention will be described.
[Evaluation items and evaluation methods]
The evaluation items and evaluation methods are as follows.
(Copolymerization composition of SMA resin (S))
^{The copolymer composition of the SMA resin (S) was determined by the 13} C-NMR method by the following procedure using a nuclear magnetic resonance apparatus (“GX-270” manufactured by JEOL Ltd.).
A sample solution was prepared by dissolving 1.5 g of SMA resin (S) in 1.5 ml of deuterated chloroform, and ¹³ C-NMR spectra were measured under the conditions of 4,000 to 5,000 integrations in a room temperature environment. The value of was calculated.
-[Integrated strength of carbon peaks (around 127, 134, 143 ppm) of the benzene ring (6 carbon atoms) in the styrene unit] / 6
-[Integral strength of carbon peak (around 170 ppm) of carbonyl moiety (carbon number 2) in maleic anhydride unit] / 2
-[Integrated strength of carbon peak (around 175 ppm) of carbonyl site (carbon number 1) in MMA unit] / 1
From the area ratio of the above values, the molar ratio of styrene unit, maleic anhydride unit, and MMA unit in the sample was determined. From the obtained molar ratio and the mass ratio of each monomer unit (styrene unit: maleic anhydride unit: MMA unit = 104: 98: 100), the mass composition of each monomer unit in the SMA resin (S). Asked.

(Weight average molecular weight (Mw))
The Mw of the resin was determined by the GPC method according to the following procedure. Tetrahydrofuran was used as the eluent, and two "TSKgel SuperMultipore HZM-M" manufactured by Tosoh Corporation and "SuperHZ4000" were connected in series as the column. As the GPC apparatus, HLC-8320 (product number) manufactured by Tosoh Corporation equipped with a differential refractive index detector (RI detector) was used. A sample solution was prepared by dissolving 4 mg of the resin in 5 ml of tetrahydrofuran. The temperature of the column oven was set to 40 ° C., 20 μl of the sample solution was injected at an eluent flow rate of 0.35 ml / min, and the chromatogram was measured. Ten standard polystyrene points having a molecular weight in the range of 400 to 5,000,000 were measured by GPC, and a calibration curve showing the relationship between the retention time and the molecular weight was prepared. Mw was determined based on this calibration curve.

(Glass transition temperature of resin (composition))
The glass transition temperature of the resin (composition) was measured by placing 10 mg of the resin (composition) in an aluminum pan and using a differential scanning calorimeter (“DSC-50”, manufactured by Rigaku Co., Ltd.). After performing nitrogen substitution for 30 minutes or more, the temperature was once raised from 25 ° C. to 200 ° C. at a rate of 20 ° C./min in a nitrogen stream of 10 ml / min, held for 10 minutes, and cooled to 25 ° C. (primary scanning). ). Next, the temperature was raised to 200 ° C. at a rate of 10 ° C./min (secondary scanning), and the glass transition temperature was calculated by the midpoint method from the results obtained by the secondary scanning. When a plurality of Tg data can be obtained in a resin composition containing two or more kinds of resins, the value derived from the resin as the main component was adopted as the Tg data.

(Surface roughness Ra of the wall surface of the flow path for the base material layer in the T die)
Using SJ-210 manufactured by Mitutoyo Co., Ltd., the surface roughness (arithmetic mean height) Ra of the wall surface between the manifold of the flow path for the base material layer in the T-die and the confluence with the flow path for the surface layer can be determined. It was measured.

(Number of die lines)
A visual inspection was performed on a laminated sheet having a width of 900 mm in a room equipped with a lit three-wavelength fluorescent lamp and having an illuminance of 2300 to 2600 lux. Among the streaky defects along the flow direction during extrusion, the number of die lines having a width of 0.3 mm or more existing at the laminated interface was counted. The formation position (surface or lamination interface) of each die line was confirmed by observing with an optical microscope in a state where the focal position was aligned with the surface and the lamination interface, respectively.

(Number of colored foreign matter defects)
A visual inspection was carried out on a laminated sheet having a size of 500 mm × 500 mm in a room equipped with a lit three-wavelength fluorescent lamp and having an illuminance of 2300 to 2600 lux. The number of colored foreign matter defects was counted by size as observed by an optical microscope of ^{0.01 mm 2} or more and ^{less than 0.30 mm 2} and 0.30 mm ^{2 or more.} It should be noted that the size of the visually recognized colored foreign matter defect is observed to be several times to several tens of times larger than the actual size of the colored foreign matter because the colored foreign matter defect which is the core of the colored foreign matter defect is raised around it.

(Re value)
A 100 mm square test piece was cut out from the laminated sheet using a running saw. After leaving this test piece in an environment of 23 ° C. ± 3 ° C. for 10 minutes or more, the Re value was measured using "WPA-100 (-L)" manufactured by Photonic Lattice Co., Ltd. The measurement point was the central part of the test piece.

[material]
The materials used are as follows.
<Polycarbonate resin (PC)>
(PC1-1)
"SD Polyca (registered trademark)" manufactured by Sumika Stylon Polycarbonate Co., Ltd. (MFR = 6.7 g / 10 minutes under a temperature of 300 ° C. and a load of 1.2 kg).
(PC1-2) 1.0 phr of ADEKA STAB AO-50 (manufactured by ADEKA Corporation), which is an antioxidant, is added to the above polycarbonate resin (PC1-1), and the mixture is melt-kneaded with a single-screw extruder. A polycarbonate resin (PC1-2) (MFR = 7.0 g / 10 minutes under a temperature of 300 ° C. and a load of 1.2 kg) was obtained.
(PC2-1)
"SD Polyca (registered trademark)" manufactured by Sumika Stylon Polycarbonate Co., Ltd. (MFR = 15.0 g / 10 minutes under a temperature of 300 ° C. and a load of 1.2 kg).
(PC2-2)
To the above polycarbonate resin (PC2-1), 1.0 phr of ADEKA STAB AO-50 (manufactured by ADEKA Corporation), which is an antioxidant, is added and melt-kneaded with a single-screw extruder to obtain a polycarbonate resin (PC2-). 2) (MFR = 15.5 g / 10 minutes under a temperature of 300 ° C. and a load of 1.2 kg) was obtained.

<Methacrylic resin (PM)>
(PM1) Polymethyl methacrylate (PMMA), "Parapet (registered trademark) HR" manufactured by Kuraray Co., Ltd. (MFR = 2.0 g / 10 minutes, Tg = 115 ° C. under a temperature of 230 ° C. and a load of 3.8 kg).

<SMA resin (S)>
(S1) SMA resin (styrene-maleic anhydride-MMA copolymer, styrene unit / maleic anhydride unit / MMA unit (mass ratio) = 56 / 18/26, Mw = 150,000, Tg = 138 ° C.) was obtained.

<Methyl resin-containing resin composition (MR1)>
(MR1-1) A methacrylic resin (PM1) and an SMA resin (S1) were mixed at a mass ratio of 30:70 to obtain a methacrylic resin-containing resin composition (MR1-1).

<Multilayer rubber particles (RP)>
(RP1) An acrylic multilayer structure having a three-layer structure in which an innermost layer (RP-a1), an intermediate layer (RP-b1), and an outermost layer (RP-c1) composed of a copolymer having the following composition are sequentially formed. Rubber particles (RP1) were produced. The particle size was 0.23 μm.
Innermost layer (RP-a1): Methyl methacrylate (MMA) unit / Methyl acrylate (MA) unit / Allyl methacrylate unit (mass ratio) which is a crosslinkable monomer = 32.91 / 2.09 / 0. 07,
Intermediate layer (RP-b1): Butyl acrylate unit / styrene unit / allyl methacrylate unit (mass ratio) which is a crosslinkable monomer = 37.00 / 8.00 / 0.90,
Outermost layer (RP-c1): Methyl methacrylate (MMA) unit / Methyl acrylate (MA) unit (mass ratio) = 18.80 / 1.20.

<Particles for dispersion (D)>
(D1) Methacrylic copolymer particles, methyl methacrylate (MMA) unit / methyl acrylate unit (mass ratio) = 90/10, particle size: 0.11 μm.

<Multilayer structure rubber particle-containing powder (RD1)>
The latex containing the multi-layered rubber particles (RP1) and the latex containing the dispersion particles (D1) were mixed at a solid content mass ratio of 67:33. The resulting mixed latex was frozen at −30 ° C. for 4 hours. Frozen latex is added to 90 ° C warm water, which is twice the amount of frozen latex, melted to form a slurry, held at 90 ° C for 20 minutes for dehydration, and dried at 80 ° C to form a multi-layered rubber particle-containing powder. (RD1) was obtained.

<Methyl resin-containing resin composition (MR2)>
(MR2-1) A methacrylic resin (PM1) and a multi-layered rubber particle-containing powder (RD1) were melt-kneaded at a mass ratio of 88:12 to obtain a methacrylic resin-containing resin composition (MR2-1).

[Example 1]
A laminated sheet was molded using the manufacturing apparatus as shown in FIG.
For the polymer filters 34 and 44 for the base material layer and the surface layer, the material of the tubular core portion is SUS304, the material of the filter portion attached to the tubular core portion is SUS316, and the material of the housing for accommodating them is SUS304. did. The materials of the single tubes 32 and 42 for the base material layer and the surface layer were SUS304. As the T-die 51, a multi-manifold die having a hard chrome plating on the inner surface was used. The surface roughness Ra of the wall surface of the flow path for the base material layer in the T-die was 10 nm.
A resin material for the base material layer (polycarbonate resin-containing material) was melt-extruded using a 150 mmφ single-screw extruder (manufactured by Toshiba Machine Co., Ltd.) as the base material layer extruder 31. A 65 mmφ single-screw extruder (manufactured by Toshiba Machine Co., Ltd.) was used as the surface layer extruder 41 to melt-extrude the surface layer resin material (methacrylic resin-containing material). These melted resins were laminated via a multi-manifold die, and a molten thermoplastic resin laminate was co-extruded from the T-die 51. The molten thermoplastic resin laminate is sandwiched between the first cooling roll 52 and the second cooling roll 53 adjacent to each other, wound around the second cooling roll 53, and the second cooling roll 53 and the third cooling roll 54 are wound. It was cooled by sandwiching it between the two and by winding it around a third cooling roll 54. The laminated sheet 56 obtained after cooling was taken up by a pair of taking-up rolls 55. The polycarbonate resin-containing layer was brought into contact with the third cooling roll 54.
As the resin material for the surface layer, a methacrylic resin-containing resin composition (MR1-1) was consistently used from beginning to end. As the resin material for the base material layer, a polycarbonate resin (PC2-2) for starting operation with a relatively low viscosity is used at the time of starting operation, and two hours after the start of operation, the polycarbonate resin for products (PC1-1) is used. I switched. After 10 hours had passed after switching to the polycarbonate resin (PC1-1) for the product, a laminated sheet for evaluation was collected.
The laminated structure, main manufacturing conditions, and evaluation results are shown in Tables 1 to 3.

[Example 2]
A laminated sheet was molded using the manufacturing apparatus as shown in FIG. The same polymer filters, single tubes, and T-dies as in Example 1 were used.
A 65 mmφ single-screw extruder (manufactured by Toshiba Machine Co., Ltd.) was used as the first surface layer extruder 41 to melt-extrude the first surface layer resin material (methacrylic resin-containing material). A resin material for the base material layer (polycarbonate resin-containing material) was melt-extruded using a 150 mmφ single-screw extruder (manufactured by Toshiba Machine Co., Ltd.) as the base material layer extruder 31. A 65 mmφ single-screw extruder (manufactured by Toshiba Machine Co., Ltd.) was used as the second surface layer extruder 41 to melt-extrude the second surface layer resin material (methacrylic resin-containing material). These melted resins were laminated via a multi-manifold die, and a molten thermoplastic resin laminate was co-extruded from the T-die 51. The molten thermoplastic resin laminate was cooled using the cooling rolls 52 to 54, and the laminated sheet 56 obtained after cooling was taken up by a pair of take-up rolls 55.
As in Example 1, as the first surface layer resin material and the second surface layer resin material, a methacrylic resin-containing resin composition (MR1-1) was consistently used from beginning to end.
Similar to Example 1, as the resin material for the base material layer, a polycarbonate resin (PC2-2) for starting operation with a relatively low viscosity is used at the time of starting operation, and for products 2 hours after the start of operation. It was switched to the polycarbonate resin (PC1-1) of. After 10 hours had passed after switching to the polycarbonate resin (PC1-1) for the product, a laminated sheet for evaluation was collected.
The laminated structure, main manufacturing conditions, and evaluation results are shown in Tables 1 to 3.

[Examples 3 to 13, Comparative Examples 1 to 3]
A laminated sheet having a two-layer structure or a three-layer structure was produced in the same manner as in Example 1 or Example 2 except that the material or thickness of each layer or the production conditions were changed. The laminated structure, main manufacturing conditions, and evaluation results are shown in Tables 1 to 3.

[Summary of results]
In Examples 1 to 13, by carrying out the production by a method that satisfies at least one of the conditions 1 to 3 described below, it is possible to produce a laminated sheet having 5 or less die lines. It was. In particular, in Examples 1 to 6, by carrying out the production by a method that satisfies all of the conditions 1 to 3 described below, it was possible to produce a laminated sheet having one or less die lines. ..
In Examples 1 to 10, when the production was carried out by a method that satisfies two or more of the conditions 1 to 3 and the condition 4, the number of die lines is 5 or less or 1 or less, and further, there are defects of colored foreign matter. We were able to manufacture a small number of laminated sheets. The SUS420J2 used as the material of the polymer filter or the single tube in Examples 11 to 13 is martensitic stainless steel.
In Examples 1 to 13, it was possible to produce a high-quality laminated sheet with fewer defects of die lines and colored foreign substances as the number of satisfied conditions increased.
In each of Examples 1 to 13, the retardation value was 50 to 330 nm, and a laminated sheet suitable for a protective cover of a liquid crystal display or a touch panel display could be manufactured.

(Condition 1) As the T-die, a multi-manifold die in which the inner wall surface is hard chrome-plated and the surface roughness Ra of the wall surface of the flow path for the base material layer is 50 nm or less is used.
(Condition 2) At the start-up of operation, a polycarbonate resin having a lower viscosity than the polycarbonate resin for products is used as the resin material for the base material layer.
(Condition 3) At the start-up of operation, a material obtained by adding an antioxidant to a polycarbonate resin at a relatively high concentration is used as the resin material for the base material layer.
(Condition 4) As the material of each part of the polymer filter and the single tube, SUS304 or SUS316, which is an austenitic stainless steel, is used.

In Comparative Examples 1 and 2, the production was carried out by a method satisfying any one of the conditions 1 to 3 and the condition 4, but the number of die lines of the obtained laminated sheet exceeded five. From the comparison between Comparative Example 1 and Example 10, it is more suitable for the base material layer in the T-die than using a resin to which an antioxidant is added at a relatively high concentration as the resin material for the base material layer at the time of starting operation. It was found that reducing the surface roughness Ra of the wall surface of the flow path contributed more to the reduction of the die line. As shown in Example 7, under the condition that the surface roughness Ra of the wall surface of the flow path for the base material layer in the T die exceeds 50 nm, the number of die lines is reduced to 5 or less by increasing the number of satisfied conditions. can do.
In Comparative Example 3, since the production was carried out by a method that does not satisfy the conditions 1 to 3, the number of die lines of the obtained laminated sheet exceeded 5, and many defects of colored foreign matter were observed.

The present invention is not limited to the above-described embodiments and examples, and the design can be appropriately changed as long as the gist of the present invention is not deviated.

This application claims priority on the basis of Japanese application Japanese Patent Application No. 2018-078605 filed on April 16, 2018, the entire disclosure of which is incorporated herein by reference.

10X, 10Y Laminated sheet 11 Base material layer 12, 12A, 12B Surface layer 30 Laminated sheet manufacturing equipment 31 Extruder for base material layer 32 Single tube for base material layer 33 Metering pump for base material layer 34 Filtration means for base material layer 41 Extruder for surface layer 42 Single tube for surface layer 43 Metering pump for surface layer 44 Filtration means for surface layer 51 T-die 52 First cooling roll 53 Second cooling roll 54 Third cooling roll 55 Take-up roll 56 Laminated sheet

Claims (10)

A laminated sheet in which a surface layer containing a methacrylic resin is laminated on at least one surface of a base material layer containing a polycarbonate resin.
A test sample with a width of 900 mm was visually inspected indoors with a lit three-wavelength fluorescent lamp and an illuminance of 2300 to 2600 lux. Laminated sheet with 5 or less sheets. When a visual inspection was performed on a 500 mm square test sample in a room equipped with a lit three-wavelength fluorescent lamp and an illuminance of 2300 to 2600 lux.
The number of colored foreign matter defects with a size of 0.01 mm ² or more and 0.30 ^{mm or less 2 is 50 or less.}
The laminated sheet according to claim 1, wherein the number of defects of colored foreign matter having a size of 0.30 mm ^{2 or more is 0.} The laminated sheet according to claim 1 or 2, wherein the surface layer contains 5 to 90% by mass of a methacrylic resin and 95 to 10% by mass of a copolymer containing an aromatic vinyl compound unit and a maleic anhydride unit. The laminated sheet according to claim 3, wherein the copolymer contains 50 to 84% by mass of an aromatic vinyl compound unit, 15 to 49% by mass of a maleic anhydride unit, and 1 to 35% by mass of a methacrylic acid ester unit. The laminated sheet according to any one of claims 1 to 4, wherein the in-plane retardation value is 50 to 330 nm at least in a part in the width direction. The laminated sheet according to any one of claims 1 to 5, which has a scratch resistant layer, an antiglare layer, or an antireflection layer on the surface layer. The laminated sheet according to any one of claims 1 to 6, which is used as a protective cover for a liquid crystal display or a touch panel display. A display with a protective cover including a liquid crystal display or a touch panel display and a protective cover made of the laminated sheet according to any one of claims 1 to 6. It has a step of co-extruding a thermoplastic resin laminate in which the surface layer containing the methacrylic resin is laminated on at least one surface of the base material layer containing the polycarbonate resin from a T-die in a molten state.
Any one of claims 1 to 6, wherein as the T-die, a T-die in which the inner wall surface is plated and the arithmetic average height (Ra) of the wall surface of the flow path for the base material layer is 50 nm or less is used. The method for manufacturing a laminated sheet according to. It has a step of filtering the resin material for the base material layer in the molten state using a polymer filter before laminating the resin material for the base material layer in the molten state and the resin material for the surface layer in the melted state.
The ninth aspect of the present invention, wherein austenitic stainless steel and / or a Ni-Cr-Mo alloy is selected as the material of each part of the polymer filter and the single tube disposed between the polymer filter and the T-die. The method for manufacturing a laminated sheet according to the description.

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