Laminated sheet and method for manufacturing the same, printed matter, molded article and method for manufacturing the same

Abstract

To provide a laminated sheet which has good ink adhesion, and has good laser machinability even under high output / high speed condition.SOLUTION: A laminated sheet (1) has a base material layer (11) and a surface layer (21) laminated on at least one surface of the base material layer (11), the base material layer (11) containing a methacrylic resin (M) containing 80 mass% or more of a methyl methacrylate unit, the surface layer (21) containing a styrenic copolymer (S), and having, in the laminated sheet (1), a concentration of a unit derived from a monomer having a lower explosive limit in air of 2.0 vol.% or less of 6.0 mass% or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a laminated sheet and a method for manufacturing the same, a printed matter, and a molded article and a method for manufacturing the same. [Background technology]

[0002] Inkjet printing, which can process digital images on a print medium using a computer, is becoming more and more versatile as the range of printable media expands. It is now widely used in a variety of fields, including printing, advertising, signage and displays, events, amusement, architecture, and interior design. Resin sheets are another printing medium besides paper. Unlike paper, resin sheets are highly water-resistant and durable, and can also be made transparent.

[0003] After inkjet printing, the resin sheet for inkjet printing can be cut into a desired shape using a laser and an NC router, if necessary. The molded product thus obtained can be preferably used for miscellaneous goods such as key holders and fixtures. A method for cutting a resin sheet using a laser is disclosed, for example, in claim 1 of Patent Document 1. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-055348 [Patent Document 2] Japanese Patent Application Publication No. 2018-94843 [Patent Document 3] Japanese Patent Publication No. 2021-160119 Summary of the Invention [Problem to be solved by the invention]

[0005] In applications such as miscellaneous goods and fixtures, such as key holders, methacrylic resins are preferably used as the base resin of resin sheets for inkjet printing from the viewpoints of transparency and ink color development. Ultraviolet (UV) curable inks are preferably used as inkjet printing inks. However, methacrylic resins tend to have poor adhesion to inkjet printing inks, such as UV curable inks. Examples of components that have good adhesion to inkjet printing inks, such as UV curable inks, include styrene copolymers.

[0006] Generally, in laser cutting, depending on the material of the workpiece, when the workpiece is melted and evaporated by laser light irradiation, an unpleasant odor or smoke may be generated due to the evaporated gas. Furthermore, after laser cutting is completed, when the molten portion cools and solidifies again, the evaporated gas may adhere to the cut surface, resulting in a poor appearance of the cut surface. Methacrylic resins are less likely to suffer from the above-mentioned problems caused by evaporated gas (unpleasant odor or smoke caused by evaporated gas, and poor appearance of the cut surface due to the adhesion of evaporated gas), and tend to have good laser cutting processability. In contrast, styrene copolymers having an aromatic ring structure in the molecule are more likely to suffer from the above-mentioned problems caused by evaporated gas (unpleasant odor or smoke caused by evaporated gas, and poor appearance of the cut surface due to the adhesion of evaporated gas), and tend to have poor laser cutting processability. Patent Documents 2 and 3 disclose a laminate sheet having a substrate layer containing a methacrylic resin and a surface layer containing a styrene copolymer such as a methyl methacrylate-styrene copolymer (MS resin), and having good ink adhesion and laser cutting processability (Claim 1 of Patent Document 2, Claim 1 of Patent Document 3). This laminate sheet can be preferably produced by coextrusion molding.

[0007] From the perspective of improving productivity of molded products, it is preferable to increase the laser output and cutting speed during laser cutting. However, under high-output and high-speed conditions, the temperature of the laser beam becomes higher, for example, over 400°C. Therefore, when exposed to laser beam, the resin decomposes thermally, and the monomer units of the resin return to monomers. The vaporized monomers at high temperatures may ignite. Furthermore, the ignition may produce soot that may adhere to the molded product. It is desirable to be able to suppress ignition and soot generation even under high-power and high-speed conditions, and to be able to perform laser cutting processing well.

[0008] Generally, in the production of (co)extrusion molded sheets and molded products using them, there are defective products that arise when the extrusion molding production line is started up, scraps that arise from the trimming process on both ends of the sheet, defective products that are determined not to meet product standards in quality inspections for defects and foreign matter, and scraps that arise from the cutting process of the sheet.In recent years, efforts have been made toward a sustainable society, and it is preferable to reuse and make effective use of the above-mentioned defective products and scraps as rework materials rather than disposing of them.

[0009] In the laminate sheets disclosed in Patent Documents 2 and 3, it is conceivable to use a previously manufactured laminate sheet containing a methacrylic resin and a styrene copolymer such as MS resin as a rework material for the base layer material. However, styrene copolymers such as MS resin generally have poor compatibility with methacrylic resins, and there is a refractive index difference between these resins. Therefore, laminate sheets using the above rework material as the base layer material may exhibit reduced transparency and become cloudy. In fact, Patent Document 3 states, "To suppress cloudiness and maintain transparency, the styrene content in the base layer is preferably 1% by mass or less, more preferably 0.85% by mass or less" (paragraph 0171). Patent Document 3 also specifies a very low preferred styrene content in the base layer. Furthermore, this document does not disclose any examples in which a previously manufactured laminate sheet containing a methacrylic resin and a styrene copolymer such as MS resin is used as a rework material. It would be preferable to be able to use a larger amount of rework material as the base layer material.

[0010] The present disclosure has been made in consideration of the above-mentioned problems, and aims to provide a laminated sheet that has good ink adhesion and good laser cutting processability even under high-power and high-speed conditions. Another object of the present disclosure is to provide a laminated sheet that has good ink adhesion, good laser cutting processability even under high-power and high-speed conditions, and excellent sustainability. [Means for solving the problem]

[0011] The present disclosure provides the following laminated sheet and manufacturing method thereof, printed matter, and molded article and manufacturing method thereof.

[0012] [1] A laminated sheet having a base layer and a surface layer laminated on at least one side of the base layer, the base layer contains a methacrylic resin (M) containing 80% by mass or more of methyl methacrylate units, the surface layer contains a styrene-based copolymer (S), The laminate sheet has a concentration of units derived from a monomer having an explosion limit in air of 2.0% by volume or less of 6.0% by mass or less.

[0013] [2] The laminate sheet according to [1], wherein the ratio of the total thickness of the surface layer to the total thickness of the laminate sheet is 0.1 to 8.0%. [3] The laminate sheet according to [1] or [2], wherein the styrene copolymer (S) is one or more styrene copolymers selected from the group consisting of methyl methacrylate-styrene copolymer (MS), acrylonitrile-styrene copolymer (AS), and styrene-maleic anhydride copolymer (SMA). [4] The laminate sheet according to [3], wherein the styrene copolymer (S) is one or more styrene copolymers selected from the group consisting of acrylonitrile-styrene copolymers (AS) containing 75 to 95% by mass of styrene units and styrene-maleic anhydride copolymers (SMA) containing 60 to 95% by mass of styrene units.

[0014] [5] The laminate sheet of [3] or [4], wherein the haze value of a 3.0 mm thick single-layer molded sheet made from the pulverized laminate sheet is 5% or less. [6] The laminate sheet according to any one of [1] to [5], wherein the content of styrene-based monomer units in the laminate sheet is 0.1 to 6.0% by mass.

[0015] [7] The laminate sheet according to any one of [1] to [6], wherein the base layer is made of a methacrylic resin composition (MR) containing a methacrylic resin (M) and a styrene copolymer (S). [8] The laminate sheet of any one of [1] to [7], wherein the content of styrene-based monomer units in the base layer is 0 to 10.0% by mass. [9] A laminate sheet according to [7], in which at least a portion of the raw materials of the base material layer is a recycled resin composition (R) consisting of crushed material of the laminate sheet manufactured in the past or a processed product of the crushed material.

[0016]

[10] The laminate sheet according to any one of [1] to [9], wherein the laminate sheet has a total thickness of 1 to 10 mm.

[11] A laminate sheet according to any one of [1] to

[10] , which is for inkjet printing and / or laser cutting.

[0017]

[12] A printed matter, in which inkjet printing is performed on the surface layer of the laminate sheet according to any one of [1] to

[11] .

[13] A molded product obtained by applying inkjet printing and laser cutting to any of the laminated sheets [1] to

[11] .

[0018]

[14] A method for manufacturing a laminate sheet according to [7], in which the laminate sheet is co-extruded using a recycled resin composition (R) consisting of crushed material of the laminate sheet manufactured in the past or a processed product of the crushed material as at least a part of the total raw materials of the base material layer.

[15] The method for manufacturing a molded product according to

[13] , wherein the laminated sheet is cut using a laser processing machine with an output of 30 W or more. [Effects of the Invention]

[0019] According to the present disclosure, it is possible to provide a laminate sheet that has good ink adhesion and good laser cutting processability even under high-power and high-speed conditions. Furthermore, according to the present disclosure, by using a styrene-based copolymer (S) contained in the surface layer that has good compatibility with the methacrylic resin (M), it is possible to provide a laminated sheet that has good ink adhesion, good laser cutting processability even under high-power and high-speed conditions, and excellent sustainability. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a schematic cross-sectional view of a laminate sheet according to a first embodiment of the present invention. [Figure 2] FIG. 3 is a schematic cross-sectional view of a laminate sheet according to a second embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0021] [Laminated sheet] The laminate sheet of the present disclosure has a base layer and a surface layer laminated on at least one side of the base layer. The base layer contains a methacrylic resin (M) containing 80 mass% or more of methyl methacrylate (MMA) units, and the surface layer contains a styrene copolymer (S). The laminate sheet of the present disclosure is suitable for inkjet printing and / or laser cutting.

[0022] An example of the laminate structure of the laminate sheet of the present disclosure is a two-layer structure having a surface layer on one side of the base layer of the first embodiment shown in FIG. 1. In the figure, reference numeral 1 denotes the laminate sheet, reference numeral 11 denotes the base layer, and reference numeral 21 denotes the surface layer. The laminate sheet of the present disclosure may include any layer other than the base layer and the surface layer, as necessary. However, the surface 21S of the surface layer 21 opposite the base layer has no other layer thereon and is an exposed surface. This exposed surface can be a printing surface on which printing is performed.

[0023] The laminate structure of the laminate sheet of the present disclosure may be a three-layer structure having surface layers on both sides of the substrate layer of the second embodiment shown in FIG. 2. In the figure, reference numeral 2 denotes the laminate sheet, reference numeral 11 denotes the substrate layer, reference numeral 22 denotes the first surface layer, and reference numeral 23 denotes the second surface layer. The second laminate sheet of the present disclosure may optionally include any layer other than the substrate layer and the surface layer. However, the surface 22S of the first surface layer 22 opposite the substrate layer and / or the surface 23S of the second surface layer 23 opposite the substrate layer do not have any other layer thereon and are exposed surfaces. This exposed surface can be a printing surface on which printing is performed. In a three-layer laminate sheet, the thickness and composition of the two surface layers may be the same or different.

[0024] The laminate sheet of the present disclosure is suitable as a resin sheet for inkjet printing. Inkjet printing methods include electrostatic suction methods, methods that use a piezoelectric element such as a piezo element to apply mechanical vibration or displacement to ink, methods that heat ink to cause foaming and utilize the resulting foaming pressure, and methods that use ultraviolet (UV) curable ink. The surface layer of the laminate sheet of the present disclosure can be inkjet printed. After inkjet printing, the laminate sheet of the present disclosure can also be cut into a desired shape using a laser, an NC router, or the like, as needed. The molded product thus obtained can be preferably used for miscellaneous goods and fixtures such as key holders. For such applications, UV-curable inks are preferably used as inkjet printing inks.

[0025] Styrenic copolymers (S) with an aromatic ring structure in the molecule generally have good permeability and adhesion to inkjet printing inks, such as UV-curable inks. However, styrenic copolymers (S) with an aromatic ring structure are not very suitable for laser cutting, and when the resin melts and evaporates upon laser irradiation, the evaporated gas may produce an unpleasant odor or smoke. Furthermore, after laser cutting is completed, when the melted part cools and solidifies again, the evaporated gas may adhere to the cut surface, resulting in poor appearance of the cut surface. Methacrylic resins (M) generally suppress the above-mentioned problems caused by evaporated gases (unpleasant odors or smoke due to evaporated gases, and poor appearance of the cut surface due to adhesion of evaporated gases), and have good laser cutting processability. However, they tend to have poor permeability to inkjet printing inks such as UV-curable inks, and poor adhesion of inkjet printing inks.

[0026] The laminate sheet of the present disclosure has a surface layer containing a styrene copolymer (S) having an aromatic ring structure in the molecule, and therefore has good permeability of inkjet printing inks such as UV-curable inks and good adhesion of inkjet printing inks. The laminated sheet of the present disclosure has a laminated structure of a base layer containing a methacrylic resin (M) and a surface layer containing a styrene copolymer (S), and the proportion of styrene monomer units in the entire laminated sheet is reduced, thereby suppressing the above-mentioned problems caused by evaporated gases during laser cutting (unpleasant odors or smoke caused by evaporated gases, and poor appearance of the cut surface caused by adhesion of evaporated gases), resulting in good laser cutting processability.

[0027] From the perspective of improving productivity of molded products, it is preferable to increase the laser output and cutting speed during laser cutting. As explained in the "Background Art" section, under high-output and high-speed conditions, the temperature of the laser beam becomes higher, for example, exceeding 400°C. Therefore, when irradiated with laser beam, the resin is thermally decomposed, and the monomer units of the resin return to monomers. The vaporized monomers at high temperatures may ignite. Furthermore, the ignition may produce soot that may adhere to the molded product.

[0028] In the laminate sheet of the present disclosure, the concentration of units derived from monomers having a lower explosion limit in air of 2.0% by volume or less (total amount if multiple types are present, unless otherwise specified) in the laminate sheet is 6.0% by mass or less, with the upper limit preferably being 5.5% by mass, more preferably 5.0% by mass, even more preferably 4.0% by mass, particularly preferably 3.0% by mass, and most preferably 2.5% by mass.

[0029] According to the research of the present inventors, it has been found that if the concentration of units derived from monomers having an explosion limit in air of 2.0% by volume or less in the laminated sheet is equal to or less than the above upper limit, even if the resin is thermally decomposed and the monomer units of the resin return to the monomers and vaporize at high temperatures, ignition and the resulting soot generation can be effectively suppressed. If the concentration of units derived from monomers whose lower explosion limit in air is 2.0% by volume or less is equal to or less than the upper limit, ignition and soot generation can be suppressed even when laser cutting is performed under high-power and high-speed conditions, and laser cutting can be performed satisfactorily. According to the present disclosure, laser cutting can be performed satisfactorily under high-power and high-speed conditions, and therefore high-quality molded products with no or almost no soot adhesion can be produced with good productivity.

[0030] A mixture of flammable gas or vapor and a combustion-supporting gas (e.g., air) can burn if the concentration of the flammable gas or vapor is within a specific range. The explosive range (also called the flammable range) is the range of concentrations at which flammable gas or vapor can burn. The lower limit (lowest concentration) of this range is also called the lower explosive limit, and the upper limit (highest concentration) of this range is also called the upper explosive limit. In this specification, unless otherwise specified, the "explosive range, lower explosion limit, and upper explosion limit" refer to the explosive range, lower explosion limit, and upper explosion limit in air.

[0031] The explosive range (lower and upper explosion limits) of flammable gases or vapors can be found in "16615 Chemical Products" (published by The Chemical Daily) and data (also called literature values) in literature such as safety data sheets (SDS) provided by reagent companies. The explosion range (lower explosion limit and upper explosion limit) of a flammable gas or vapor can be measured by a known explosion test method using a known explosion test device. The explosive range (lower and upper explosive limits) of flammable gas or vapor can be measured using the method specified by the Technology Association of Industrial Safety, a public interest incorporated association. General measurement conditions are as follows: Measurement pressure: atmospheric pressure, Measurement temperature: Flash point +50℃~Flash point +70℃.

[0032] Literature values ​​for physical properties such as the lower and upper explosion limits of major monomers are shown in Table 1. The data in Table 1 are from "16615 Chemical Products (2015 Edition)" (published by The Chemical Daily).

[0033] [Table 1]

[0034] Among the monomers shown in Table 1, monomers such as styrene (St) and α-methylstyrene (αMSt) have an explosion limit in air of 2.0% by volume or less. Compared to monomers with an explosion limit in air of more than 2.0% by volume, monomers with an explosion limit in air of 2.0% by volume or less tend to be more likely to ignite when laser cut under high-power and high-speed conditions. Examples of monomers having an explosion limit in air of 2.0% by volume or less include styrene-based monomers such as styrene (St) and α-methylstyrene (αMSt); acrylic acid esters such as ethyl acrylate and butyl acrylate; and dienes such as butadiene and isoprene.

[0035] The content of styrene-based monomer units in the laminate sheet of the present disclosure (also referred to as the average concentration of styrene-based monomer units in the laminate sheet) is 6.0 mass % or less. The upper limit is preferably 5.5% by mass, more preferably 5.0% by mass, even more preferably 4.0% by mass, particularly preferably 3.0% by mass, and most preferably 2.5% by mass. The lower limit is preferably 0.1% by mass, more preferably 0.2% by mass, even more preferably 0.3% by mass, even more preferably 0.4% by mass, even more preferably 0.5% by mass, even more preferably 0.8% by mass, even more preferably 1.0% by mass, particularly preferably 1.5% by mass, and most preferably 2.0% by mass. When the average concentration of styrene-based monomer units in the laminated sheet is equal to or less than the upper limit, it is possible to suppress unpleasant odors or smoke due to evaporated gases during laser cutting, and to suppress the appearance of the cut surface due to adhesion of evaporated gases. Furthermore, even when laser cutting is performed under high-power and high-speed conditions, it is possible to suppress ignition and soot generation, and laser cutting can be performed smoothly. When the average concentration of the styrene-based monomer units in the laminate sheet is equal to or greater than the above lower limit, good ink adhesion can be ensured.

[0036] In the laminate sheet of the present disclosure, the ratio of the total thickness of the surface layer to the total thickness of the laminate sheet is not particularly limited, but is preferably 0.1 to 8.0%. The lower limit is more preferably 0.5%, even more preferably 1.0%, particularly preferably 1.5%, and most preferably 2.0%. The upper limit is more preferably 7.0%, even more preferably 6.0%, even more preferably 5.0%, particularly preferably 4.0%, and most preferably 3.0%. When the ratio of the total thickness of the surface layer is equal to or greater than the lower limit, the thickness of the surface layer containing the styrene copolymer (S) is sufficiently ensured, ensuring good ink adhesion. Furthermore, when the ratio of the total thickness of the surface layer is equal to or less than the upper limit, the content of styrene monomer units in the laminate sheet can be reduced, suppressing unpleasant odors or smoke due to evaporated gases during laser cutting, and poor appearance of the cut surface due to adhesion of evaporated gases. Furthermore, even when laser cutting is performed under high-power, high-speed conditions, fire and soot generation can be suppressed, ensuring good laser cutting.

[0037] In the laminate sheet of the present disclosure, the total thickness of the laminate sheet is not particularly limited, and is preferably 1 to 10 mm, more preferably 1 to 5 mm, in order to improve inkjet printability and laser cutting processability. For example, when the total thickness of the laminate sheet is 3 mm, the thickness of the base layer is preferably 2.40 to 2.94 mm, the thickness of one surface layer is preferably 30 to 300 μm, and the total thickness of the surface layers is preferably 30 to 600 μm.

[0038] The laminated sheets of the present disclosure are preferably coextruded sheets. The haze value of the laminate sheet of the present disclosure is preferably 5% or less, more preferably 4% or less, even more preferably 3% or less, particularly preferably 2% or less, and most preferably 1% or less. Furthermore, the haze value of a 3.0 mm thick monolayer molded sheet made from the pulverized laminate sheet of the present disclosure is preferably 5% or less, more preferably 4% or less, even more preferably 3% or less, particularly preferably 2% or less, and most preferably 1% or less. The haze value of the monolayer molded sheet can be achieved by using a styrene copolymer (S) contained in the surface layer that is compatible with the methacrylic resin (M). If the haze value of the monolayer molded sheet is 5% or less, a highly transparent laminate sheet of the present disclosure can be produced using a recycled resin composition (R) made from pulverized previously produced laminate sheet of the present disclosure or a processed product of the pulverized material as at least a portion of the total raw material for the base layer. The monolayer molded sheet of the present disclosure having a haze value of 5% or less can be used as a rework material or can contain rework material, making it highly sustainable. In this specification, unless otherwise specified, "transparent" is defined as a haze value of 5% or less.

[0039] A 3.0 mm thick single-layer molded sheet of the pulverized laminate sheet of the present disclosure can be obtained by a known method, for example, as follows. The laminated sheet of the present disclosure is pulverized using a known resin pulverizer. The resulting pulverized material is melt-kneaded using an extruder and a kneading / extrusion tester ("Labo Plastomill (registered trademark)" manufactured by Toyo Seiki Seisaku-sho, Ltd.) to obtain a homogeneous resin composition. The resulting molten kneaded material is molded by a known method such as heat press molding to obtain a single-layer molded sheet having a thickness of 3.0 mm. The melt-kneading temperature and molding temperature in molding the monolayer molded sheet are preferably within the range of suitable melt-kneading temperatures for the base layer material when molding (preferably co-extrusion molding) the laminate sheet of the present disclosure, and may be, for example, the maximum temperature in the extruder used for melt-kneading the base layer material when molding (preferably co-extrusion molding) the laminate sheet of the present disclosure. The melt-kneading temperature and molding temperature in molding the monolayer molded sheet are preferably 190 to 280°C, more preferably 210 to 270°C, particularly preferably 230 to 260°C, and for example, 250°C is preferred. For specific examples of a method for forming a single-layer sheet and a method for measuring the haze value thereof, please refer to the section "Examples" below.

[0040] (Surface layer) The surface layer contains one or more styrene copolymers (S). Examples of the styrene monomer units contained in the styrene copolymers (S) include styrene (St), α-methylstyrene (αMSt), o-, m-, or p-methylstyrene, and combinations thereof, with styrene (St) being preferred. As described above, in the present disclosure, the styrene copolymer (S) used has good compatibility with the methacrylic resin (M). From the viewpoint of compatibility with the methacrylic resin (M), the styrene copolymer (S) may be one or more styrene copolymers selected from the group consisting of acrylonitrile-styrene copolymers (AS resins), styrene-maleic anhydride copolymers (SMA resins), and methyl methacrylate-styrene copolymers (MS resins). Among the above, one or more styrene copolymers selected from the group consisting of acrylonitrile-styrene copolymers (AS resins) and styrene-maleic anhydride copolymers (SMA resins) are preferred because of their excellent compatibility with the methacrylic resin (M). Acrylonitrile-styrene copolymers (AS resins), styrene-maleic anhydride copolymers (SMA resins), or combinations thereof are more preferred.

[0041] From the viewpoint of compatibility with the methacrylic resin (M), the content of styrene units in the acrylonitrile-styrene copolymer (AS resin) is preferably 75 to 95% by mass. The lower limit is more preferably 76% by mass, and particularly preferably 77% by mass. The upper limit is more preferably 90% by mass, even more preferably 88% by mass, particularly preferably 85% by mass, and most preferably 83% by mass. Commercially available AS resins include "Lithac-A 100PCF" and "120PCF" manufactured by Nippon A&L, Inc.; "Sunrex SAN-C," "SAN-R," and "SAN-H" manufactured by Techno UMG; "Denka AS AS-C-800" and "AS-C-820" manufactured by Denka; "Toyolac" manufactured by Toray Industries, Inc.; and "Cevian N" manufactured by Daicel Miraize Co., Ltd. Among these, "Lithac-A 100PCF" manufactured by Nippon A&L, Inc.; "Sunrex SAN-C" manufactured by Techno UMG; and "Denka AS AS-C-820" manufactured by Denka are preferred.

[0042] From the viewpoint of compatibility with the methacrylic resin (M), the content of styrene units in the styrene-maleic anhydride copolymer (SMA resin) is preferably 60 to 95% by mass. The lower limit is more preferably 70% by mass, and particularly preferably 75% by mass. The upper limit is more preferably 90% by mass, particularly preferably 85% by mass, and most preferably 80% by mass. Commercially available SMA resins include "XIRAN" and "XIBOND" manufactured by Polyscope; "SMA-700" manufactured by Jiaxing Huawen Chemical; and "SAM-020" manufactured by Fine-blend Polymer.

[0043] In the surface layer, the total amount of one or more styrene copolymers selected from the group consisting of methyl methacrylate-styrene copolymer (MS resin), acrylonitrile-styrene copolymer (AS resin), and styrene-maleic anhydride copolymer (SMA resin) is preferably 51 to 100% by mass, with the lower limit being more preferably 65% ​​by mass, particularly preferably 70% by mass, and most preferably 80% by mass.

[0044] A small amount of methyl methacrylate-styrene copolymer (MS resin) is compatible with the methacrylic resin (M) and can be used. When using a methyl methacrylate-styrene copolymer (MS resin), it is preferable to use it in combination with a styrene copolymer that has excellent compatibility with the methacrylic resin (M), such as an acrylonitrile-styrene copolymer (AS resin) or a styrene-maleic anhydride copolymer (SMA resin). The amount of methyl methacrylate-styrene copolymer (MS resin) in the surface layer is preferably 0 to 1.5% by mass. The upper limit is more preferably 1.2% by mass, particularly preferably 1.0% by mass, and most preferably 0.85% by mass. From the viewpoint of compatibility with the methacrylic resin (M), the content of styrene units in the methyl methacrylate-styrene copolymer (MS resin) is preferably 35 to 50% by mass. The upper limit is more preferably 45% by mass. Commercially available MS resins include "Toyo MS MS600" manufactured by Toyo Styrene Co., Ltd., "Denka TX Polymer TX-100S" manufactured by Denka Co., Ltd., and "Cevian NAS" manufactured by Daicel Miraize Co., Ltd.

[0045] Acrylonitrile-butadiene-styrene copolymer (ABS resin), methyl methacrylate-butadiene-styrene copolymer (MBS resin), and high impact polystyrene graft-copolymerized with butadiene (HIPS resin) are not compatible with methacrylic resin (M), so it is preferable not to use them as styrene copolymer (S).

[0046] The surface layer may optionally contain one or more methacrylic resins (M) and / or one or more other acrylic resins (A) other than the methacrylic resin (M). Examples of the optional other acrylic resin (A) are the same as those for the substrate layer. The methacrylic resin (M) in the surface layer may be the same as or different from the methacrylic resin (M) in the substrate layer. The same applies to the optional other acrylic resin (A).

[0047] The surface layer may optionally contain one or more polymers other than the styrene polymer (S), methacrylic resin (M), and other acrylic resin (A). The other polymers are not particularly limited, and examples thereof include polyolefins such as polyethylene and polypropylene; other thermoplastic resins such as polyamide, polyphenylene sulfide, polyether ether ketone, polyester, polysulfone, polyphenylene oxide, polyimide, polyetherimide, and polyacetal; and thermosetting resins such as phenolic resin, melamine resin, silicone resin, and epoxy resin. The content of the other polymer in the surface layer is preferably 0 to 10% by mass. The upper limit is more preferably 5% by mass, and particularly preferably 2% by mass. The surface layer may contain no other polymers other than the styrene polymer (S), methacrylic resin (M), and other acrylic resin (A).

[0048] The surface layer may contain various additives as needed. Examples of additives include colorants, antioxidants, heat degradation inhibitors, UV absorbers, light stabilizers, lubricants, release agents, polymer processing aids, antistatic agents, flame retardants, light diffusing agents, matting agents, rubber components (impact modifiers) such as core-shell particles and block copolymers, and fluorescent materials. The content of the additives can be appropriately set within a range that does not impair the effects of the present invention. For example, the content of the antioxidant is preferably 0.01 to 1 part by mass, the content of the UV absorber is preferably 0.01 to 3 parts by mass, the content of the light stabilizer is preferably 0.01 to 3 parts by mass, and the content of the lubricant is preferably 0.01 to 3 parts by mass, per 100 parts by mass of the constituent resins of the surface layer (100 parts by mass in total if multiple types are used). When other polymers and / or additives are added to the surface layer, the timing of addition may be during or after polymerization of the styrene copolymer (S).

[0049] The glass transition temperature (Tg) of the constituent resin of the surface layer (a mixed resin composition when multiple types are used) is not particularly limited, but is preferably 80 to 160°C, more preferably 100 to 110°C.

[0050] (base material layer) The substrate layer contains one or more methacrylic resins (M). The methacrylic resins (M) are homopolymers or copolymers containing methyl methacrylate (MMA) units. From the viewpoint of transparency, the content of MMA units in the methacrylic resins (M) is 80 to 100% by mass. The lower limit is preferably 90% by mass, more preferably 95% by mass.

[0051] The methacrylic resin (M) may contain one or more (meth)acrylic acid ester units other than MMA units. Examples of (meth)acrylic acid esters other than MMA include methyl acrylate (MA), ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, stearyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, and 2-hydroxypropyl (meth)acrylate. Examples of suitable copolymers include acrylate, 4-hydroxybutyl (meth)acrylate, cyclohexyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate, trifluoromethyl (meth)acrylate, trifluoroethyl (meth)acrylate, pentafluoroethyl (meth)acrylate, glycidyl (meth)acrylate, allyl (meth)acrylate, phenyl (meth)acrylate, toluyl (meth)acrylate, benzyl (meth)acrylate, isobornyl (meth)acrylate, and 3-dimethylaminoethyl (meth)acrylate. Among these, MA is preferred from the viewpoint of transparency. For example, a copolymer of MMA and MA is preferred because it has excellent transparency. In this specification, (meth)acrylic is a general term for acrylic and methacrylic, and the same applies to (meth)acrylic acid, (meth)acrylonitrile, and the like.

[0052] The substrate layer may optionally contain one or more other acrylic resins (A) other than the methacrylic resin (M). In this specification, the "other acrylic resins (A)" refer to methacrylic resins having an MMA unit content of less than 80 mass% and (meth)acrylic resins that do not contain MMA units but contain one or more (meth)acrylic acid ester units other than MMA units.

[0053] The methacrylic resin (M) and the other acrylic resin (A) may contain structural units derived from one or more other monomers other than (meth)acrylic acid esters. Examples of such other monomers include (meth)acrylic acid, (meth)acrylic acid metal salts, (meth)acrylonitrile, (meth)acrylamide, vinyl monomers such as vinyl chloride and vinyl acetate, acid anhydrides such as maleic anhydride, maleimides such as phenylmaleimide and cyclohexylmaleimide, and styrene monomers such as styrene, α-methylstyrene, and vinyltoluene. The content (total amount if multiple types) of structural units derived from monomers other than (meth)acrylic acid esters in the methacrylic resin (M) and the other acrylic resin (A) is 0 to 10% by mass, with the upper limit being more preferably 5% by mass, and particularly preferably 2% by mass. The content of styrene monomer units in the methacrylic resin (M) and other acrylic resin (A) (the total amount if multiple types) is preferably 0 to 1.5 mass %, with the upper limit being more preferably 1.2 mass %, particularly preferably 1.0 mass %, and most preferably 0.85 mass %. The methacrylic resin (M) and the other acrylic resin (A) may not contain a styrene monomer unit.

[0054] As shown in Table 1, acrylic esters such as ethyl acrylate and butyl acrylate are monomers whose lower explosion limit in air is 2.0% by volume or less. Therefore, it is preferable that the methacrylic resin (M) and other acrylic resin (A) contain a small amount or no units derived from monomers whose lower explosion limit in air is 2.0% by volume or less. As the methacrylic resin (M), polymethyl methacrylate (PMMA), methyl methacrylate-methyl acrylate copolymer, and the like are preferred.

[0055] The methacrylic resin (M) and other acrylic resin (A) are obtained by polymerizing one or more (meth)acrylic acid esters and, if necessary, other monomers. When using multiple types of monomers, the multiple types of monomers are usually mixed to prepare a monomer mixture, and then polymerization is carried out. The polymerization method is not particularly limited, and from the viewpoint of productivity, radical polymerization methods such as bulk polymerization, suspension polymerization, solution polymerization, and emulsion polymerization are preferred.

[0056] The substrate layer may contain one or more styrene copolymers (S) as needed. That is, the substrate layer may be made of a methacrylic resin composition (MR) containing a methacrylic resin (M) and a styrene copolymer (S). The styrene copolymer (S) in the substrate layer may be the same as or different from the styrene copolymer (S) in the surface layer. When the base layer contains a styrene-based monomer unit, the amount of change in warpage of the laminate sheet after being left standing in a high-humidity environment tends to be effectively reduced.

[0057] Generally, in the production of (co)extrusion molded sheets and molded products using them, there are defective products that arise when the extrusion molding production line is started up, scraps that arise from the trimming process on both ends of the sheet, defective products that are determined not to meet product standards in quality inspections for defects and foreign matter, and scraps that arise from the cutting process of the sheet.In recent years, efforts have been made toward a sustainable society, and it is preferable to reuse and make effective use of the above-mentioned defective products and scraps as rework materials rather than disposing of them. In this specification, "virgin material" refers to a molding material that has never been subjected to molding processing in the past, and "rework material" refers to a molding material that has been molded into a molded product at least once in the past. At least a portion of the raw materials for the base layer can be a recycled resin composition (R) (also called a rework material) made from crushed or processed materials of the laminated sheet of the present disclosure that was previously manufactured. Examples of the processed materials include strands and pellets. If the haze value of a 3.0 mm thick single-layer molded sheet made from the pulverized laminate sheet of the present disclosure is 5% or less, a laminate sheet of the present disclosure having excellent transparency can be manufactured using a recycled resin composition (R) made from pulverized laminate sheets of the present disclosure that have been manufactured in the past or processed products of the pulverized materials as at least a portion of the total raw materials for the base layer.

[0058] The content of the styrene-based monomer unit in the base layer is not particularly limited, and is preferably 0 to 10.0% by mass. Patent Document 3, cited in the [Background Art] section, states that "in order to suppress the occurrence of cloudiness and maintain transparency, the styrene content in the base layer is preferably 1% by mass or less, more preferably 0.85% by mass or less" (paragraph 0171). When a styrene copolymer (S) having good compatibility with the methacrylic resin (M) is used, the content of the styrene monomer unit in the base layer can be made larger than the range described in Patent Document 3, and can be set to 1.2% by mass or more, 1.5% by mass or more, or 2.0% by mass or more. The upper limit is more preferably 9.0% by mass, even more preferably 8.0% by mass, still more preferably 7.0% by mass, particularly preferably 6.0% by mass, and most preferably 5.0% by mass.

[0059] The substrate layer may optionally contain one or more polymers other than the methacrylic resin (M), the other acrylic resin (A), and the styrene polymer (S). The substrate layer may optionally contain various additives. Examples of the types and preferred amounts of the other polymers and additives are the same as those for the surface layer.

[0060] The glass transition temperature (Tg) of the constituent resin of the base layer (a mixed resin composition when multiple types are used) is not particularly limited, but is preferably 100 to 140°C, more preferably 105 to 135°C, and particularly preferably 105 to 125°C.

[0061] [Laminated sheet manufacturing method] The laminate sheet of the present disclosure can be produced by a known sheet molding method, and from the viewpoints of production efficiency and interlayer adhesion, an extrusion molding method is preferred. In the case of the extrusion molding method, coextrusion molding is preferred in which a base layer material containing a methacrylic resin (M) and a surface layer material containing a styrene copolymer (S) are melt-kneaded using different extruders and coextruded from a common extrusion die (such as a T-die).

[0062] Coextrusion die types include a multi-manifold die type and a field block type. In the feed block type, a molten base layer material containing a methacrylic resin (M) and a molten surface layer material containing a styrene copolymer (S) are laminated in a feed block, then introduced into a T-die or the like to be formed into a sheet and co-extruded. In the multi-manifold die type, a molten base layer material containing a methacrylic resin (M) and a molten surface layer material containing a styrene copolymer (S) are introduced into a T-die or the like to be formed into a sheet, then laminated and co-extruded. In the laminate sheet of the present disclosure, the surface layer is designed to be thin. In this case, the multi-manifold die type is preferred. In either method, the thermoplastic resin laminate extruded from a T-die or the like is cooled by passing through a gap between at least a pair of cooling pressure rolls, and then taken up by a take-up roll. The above co-extrusion, cooling, and take-up steps are carried out continuously. In this specification, the heated and molten state is mainly referred to as a "thermoplastic resin laminate," and the solidified state is referred to as a "laminate sheet," but there is no clear boundary between the two.

[0063] In the co-extrusion molding of the laminate sheet of the present disclosure, the die temperature (Td) is preferably 190 to 280°C. If Td is less than 190°C, the melt viscosity of the methacrylic resin (M) and the styrene copolymer (S) may become too high, making it difficult to extrude these resins satisfactorily. If Td exceeds 280°C, the styrene copolymer (S) may decompose due to the high temperature. Td is more preferably 210 to 270°C, and particularly preferably 230 to 260°C. The lip thickness of the T-die is designed according to the desired total thickness of the laminated sheet (preferably 1 to 10 mm). The take-up speed (V) of the laminated sheet by the pair of take-up rolls is not particularly limited, and is preferably 0.5 to 2.0 m / min.

[0064] In the manufacturing method of the laminate sheet of the present disclosure, the laminate sheet of the present disclosure can be co-extruded using a recycled resin composition (R) consisting of pulverized material of a laminate sheet of the present disclosure that was previously manufactured or a processed product of the pulverized material as at least a portion of the total raw material of the base layer. The proportion of the recycled resin composition (R) in all raw materials for the base layer is not particularly limited and can be, for example, 1 to 100% by mass. In the technology of the present disclosure, the proportion of the recycled resin composition (R) in all raw materials for the base layer can be increased, and can be 10 to 100% by mass, 20 to 100% by mass, 30 to 100% by mass, 40 to 100% by mass, or 50 to 100% by mass.

[0065] Generally, repeated reworking of the same material can lead to a deterioration in the quality of the rework material, which can increase the haze value of the laminated sheet. It is therefore preferable to adjust the proportion of the rework material used, taking into account the number of reworks or the quality of the rework material. When a styrene copolymer (S) having good compatibility with the methacrylic resin (M) is used, even if at least a portion of the total raw materials of the base layer is a recycled resin composition (R) consisting of pulverized laminate sheets of the present disclosure that were previously manufactured or processed from the pulverized materials, the laminate sheets of the present disclosure can have excellent transparency and a haze value of 5% or less, 4% or less, 3% or less, 2% or less, or 1% or less.

[0066] [Printed materials, molded products] The laminate sheet of the present disclosure can be preferably used as a resin sheet for inkjet printing. A printed material can be produced by inkjet printing on a surface layer containing a styrene copolymer (S) contained in the laminate sheet of the present disclosure. After inkjet printing, the laminate sheet of the present disclosure can also be cut, if necessary, using a laser and an NC router to form it into a desired shape.

[0067] The laminate sheet of the present disclosure has good laser cutting processability, allowing for fine cutting. For example, molded products having curved cut portions with a radius of 0.5 to 2 mm can be produced with good shape accuracy. Because the laminate sheet of the present disclosure has good laser cutting processability, it can be cut at high speed and with good productivity using a high-power laser processing machine.

[0068] The output of the laser processing machine (also referred to as laser output) is preferably 30 W or more. The lower limit is more preferably 40 W, even more preferably 50 W, particularly preferably 60 W, and most preferably 70 W. The upper limit is, for example, 100 W. For example, when the total thickness of the laminated sheet is 3 mm, the laser cutting speed is preferably 100 cm / min or more. The lower limit is more preferably 120 cm / min, even more preferably 130 cm / min, particularly preferably 140 cm / min, and most preferably 150 cm / min. The upper limit is, for example, 200 cm / min.

[0069] As described above, according to the present disclosure, it is possible to provide a laminate sheet that has good ink adhesion and good laser cutting processability even under high-power, high-speed conditions. Furthermore, according to the present disclosure, by using a styrene-based copolymer (S) contained in the surface layer that has good compatibility with the methacrylic resin (M), it is possible to provide a laminated sheet that has good ink adhesion, good laser cutting processability even under high-power and high-speed conditions, and excellent sustainability.

[0070] [Application] The laminated sheets, printed materials, and molded articles of the present disclosure can be used in a variety of fields, such as printing, advertising, sign displays, events, amusement, architecture, and interior design. The laminated sheet, printed matter, and molded article of the present disclosure can be preferably used for miscellaneous goods such as key holders, fixtures, and the like. [Example]

[0071] Examples and comparative examples according to the present invention will be described below. [Evaluation items and evaluation methods] (Content of styrene-based monomer units in styrene-based copolymer (S)) Using a nuclear magnetic resonance spectrometer (Bruker "ULTRA SHIELD 400 PLUS"), the styrene copolymer (S) 1 The H-NMR spectrum was measured. The styrene unit concentration was calculated from the integral value of the peaks derived from the hydrogen atoms bonded to the carbon atoms at positions 2 to 6 of the aromatic ring contained in styrene.

[0072] (Haze value of 3.0 mm thick single-layer molded sheet made from crushed sheet) 60 g was weighed out from the laminated sheet and pulverized using a pulverizer. The pulverized material was then melt-kneaded using a Toyo Seiki Seisakusho "Laboplastomill (registered trademark)" at a screw speed of 70 rpm, a kneading time of 3 minutes, and a kneading temperature of 250°C. The resulting molten kneaded material was then hot-press molded using a 50 mm x 150 mm mirror-finished mold at a molding temperature of 250°C to obtain a 3.0 mm thick single-layer molded sheet. The melt-kneading temperature and molding temperature (both 250°C) were the maximum temperatures of the extruder for the base layer material used in the [Examples] section. The haze value of the resulting single-layer molded sheet was measured using an "HM-150" manufactured by Murakami Color Research Laboratory.

[0073] (Haze value of single layer sheet or laminated sheet) A 50 mm x 50 mm test piece was cut out from the center of the width direction of the single layer sheet or laminate sheet, and the haze value was measured using "HM-150" manufactured by Murakami Color Research Laboratory.

[0074] (ink adhesion) Ink adhesion was evaluated on inkjet-printed laminated or single-layer sheets. A 10mm square evaluation area was cross-cut into 100 squares (10 squares vertically and 10 squares horizontally) at 1mm intervals in the printed layer, consisting of cured white and black UV-curable inks. Cellophane tape was applied to the entire evaluation area, and then rubbed with an eraser to ensure that the cellophane tape adhered well to the printed surface. The cellophane tape was then peeled off at a 90° angle. Observation was performed using a 10x magnification loupe, and the number of squares in which the ink had peeled off from the resin sheet was counted out of the 100 squares evaluated. The evaluation criteria were as follows: A (Excellent): No ink peeling was observed in any of the squares. B (Good): Ink peeling was observed in 1 or more but less than 10 squares. C (Acceptable): Ink peeling was observed in 10 or more but less than 50 squares. D (Fail): Ink peeling was observed in 50 or more squares.

[0075] (Laser cutting processability) The inkjet-printed laminated or single-layer sheets were evaluated for laser cutting processability. <Whether or not there was a fire> During the laser cutting process, the laser irradiated area of ​​the laminated or single-layer sheet (the laser irradiated area and its vicinity) was visually observed, and the presence or absence of ignition was evaluated by organoleptic evaluation. The evaluation criteria were as follows: A (good): No sparks were observed in the laser irradiated area, and no soot was observed on the laminated sheet after cutting. B (Acceptable): Sparks were occasionally observed in the laser irradiated area, but no soot was observed on the laminated sheet after cutting. C (poor): Sparks were always or frequently observed in the laser irradiated area, and soot was observed on the laminated sheet after cutting.

[0076] [material] The materials used are as follows: (Methacrylic resin (M)) <pmma1>Methyl methacrylate-methyl acrylate copolymer, "Parapet" manufactured by Kuraray Co., Ltd., methyl methacrylate unit content: 94% by mass, methyl acrylate unit content: 6% by mass, styrene unit content: 0% by mass.

[0077] (Acrylonitrile-styrene copolymer (AS resin)) <as1>Nippon A&L "Lytac-A 100PCF", styrene unit content: 77% by mass, <as2>Techno UMG's "Sunrex SAN-C", styrene unit content: 79% by mass, <as3>Denka AS AS-C-820 manufactured by Denka Co., Ltd., styrene unit content: 82% by mass, <as4>Denka AS GR-AT-6S, styrene unit content: 67% by mass

[0078] (Methyl methacrylate-styrene copolymer (MS resin)) <ms600>Toyo Styrene Co., Ltd. "Toyo MS MS600", styrene unit content: 40% by mass, <ms200>"Toyo MS MS200" manufactured by Toyo Styrene Co., Ltd., styrene unit content: 80% by mass.

[0079] [Manufacturing of laminated or single layer sheets] (Example (E1-V) ~ (E5-V), (E7-V), (E8-V), (E10-V), (E11-V), Comparative example (EC6-V), (EC9-V), (EC12-V)) Virgin methacrylic resin (M) was melted as the base layer material using a 150mmφ single-screw extruder (maximum cylinder temperature: 250°C) manufactured by Toshiba Machine Co., Ltd. Virgin styrene copolymer (S) was melted as the surface layer material using a 65mmφ single-screw extruder (maximum cylinder temperature: 240°C) manufactured by Toshiba Machine Co., Ltd. Using a multi-manifold die, the molten styrene copolymer (S), the molten methacrylic resin (M), and the molten styrene copolymer (S) were laminated in this order, extruded through a T-die, cooled using four adjacent cooling rolls, and taken up by a take-up roll. Through this coextrusion process, three-layer laminate sheets (L1-V) to (L12-V) were produced, each consisting of a styrene copolymer (S) (first surface layer), a methacrylic resin (M) (base layer), and a styrene copolymer (S) (second surface layer). The first and second surface layers had the same composition and thickness. For example, in Example (E1-V), the thickness of the first surface layer was 0.03 mm, the thickness of the second surface layer was 0.03 mm, the thickness of the base layer was 2.94 mm, and the total thickness of the laminate sheet was 3.0 mm. The main manufacturing conditions and various parameter values ​​are shown in Table 2. In these tables, conditions not listed in the tables are common conditions.

[0080] (Comparative example (EC21-V)~(EC23-V)) Virgin methacrylic resin (M) or virgin styrene copolymer (S) was melted using a 150 mm diameter single-screw extruder (Toshiba Machine Co., Ltd.) (maximum cylinder temperature: 250°C). The molten resin was extruded through a T-die, cooled using four adjacent cooling rolls, and taken up by a take-up roll. 3.0 mm thick single-layer sheets (L21-V) to (L23-V) were produced by this extrusion molding. The main manufacturing conditions and various parameter values ​​are shown in Table 3.

[0081] (Example (E1-R)~(E4-R), (E7-R), (E8-R), (E10-R), Comparative example (EC5-R), (EC6-R), (EC9-R), (EC11-R), (EC12-R)) Laminated sheets (L1-R) to (L12-R) were obtained in the same manner as in the Examples or Comparative Examples shown in Table 2, except that a portion (50 mass%) of the base layer material was replaced with a pulverized product of the laminated sheet obtained in the Examples or Comparative Examples shown in Table 2 as a rework material. The main manufacturing conditions and various parameter values ​​are shown in Table 4. The virgin methacrylic resin (M) and the rework material were mixed by dry blending.

[0082] [Inkjet printing] Inkjet printing was carried out on one surface of the laminated or single-layer sheet obtained in each example under the following conditions, and the ink adhesion was evaluated as described above. The printing pattern was a solid print of an approximately ellipse with a minor axis of 1.8 cm and a major axis of 2.8 cm. Equipment: Mimaki Engineering "UJF-7151 plusII" Temperature: room temperature (20~25℃), UV-curable ink: Mimaki Engineering "LH-100" (magenta).

[0083] [Laser cutting] The inkjet printed laminated or single layer sheet was subjected to laser cutting under the following conditions 1 or 2 to obtain a molded product in the shape of a TV anime character, measuring 20 mm in minor axis x 30 mm in major axis and having a curved cut section with a radius of 1 mm. Equipment: Trotec "Speedy360" Temperature: room temperature (20~30℃), Laser type: carbon dioxide laser, Condition 1 (normal output and normal speed conditions): Laser output 40 W, processing speed 108 cm / sec, Condition 2 (high power and high speed conditions): Laser power: 80 W, processing speed: 162 cm / sec.

[0084] [Evaluation results] The evaluation results are shown in Tables 2 to 4.

[0085] [Table 2]

[0086] [Table 3]

[0087] [Table 4]

[0088] In Examples (E1-V) to (E5-V), (E7-V), (E8-V), (E10-V), and (E11-V), only virgin materials were used as the materials for the base layer and surface layer. In these examples, acrylonitrile-styrene copolymer (AS) or methyl methacrylate-styrene copolymer (MS) was used as the styrene copolymer (S). In these examples, laminate sheets were produced in which a base layer containing a methacrylic resin (M) was laminated on both sides with surface layers containing a styrene copolymer (S), and the ratio of the total thickness of the surface layers to the total thickness of the laminate sheet was 0.1 to 8.0%. The laminated sheets obtained in these examples all had good ink adhesion. In these examples, the concentration of monomer units (specifically styrene units in these examples) derived from monomers with an explosion limit in air of 2.0% by volume or less in the laminate sheet was 6.0% by mass or less. All of the obtained laminate sheets had good laser cutting processability under both normal power / normal speed conditions and high power / high speed conditions.

[0089] The styrene copolymer (S) used in Examples (E1-V) to (E5-V) and (E8-V), especially Examples (E1-V) to (E5-V), had good compatibility with the methacrylic resin (M), and the haze value of the resulting 3.0 mm-thick single-layer molded sheet obtained by pulverizing the laminated sheet was 5% or less, and the transparency was good. In these examples, a laminated sheet with excellent sustainability that can be used as a rework material was obtained.

[0090] In Comparative Examples (EC6-V), (EC9-V), and (EC12-V), only virgin materials were used as the material for the base layer and surface layer. In these examples, acrylonitrile-styrene copolymer (AS) or methyl methacrylate-styrene copolymer (MS) was used as the styrene copolymer (S). In these examples, a base layer containing a methacrylic resin (M) was laminated on both sides with surface layers containing a styrene copolymer (S), and a laminate sheet was produced in which the ratio of the total thickness of the surface layers to the total thickness of the laminate sheet was more than 8.0%. The laminated sheets obtained in these examples all had good ink adhesion. In these examples, the concentration of monomer units (specifically styrene units in these examples) derived from monomers with an explosion limit in air of 2.0% by volume or less in the laminated sheet exceeded 6.0% by mass. All of the obtained laminated sheets had poor laser cutting processability under high-power and high-speed conditions.

[0091] The comparative example (EC21-V), a single-layer sheet made of a methacrylic resin (M) that does not have an aromatic ring structure in its molecule, exhibited good laser cutting processability under both normal power / normal speed conditions and high power / high speed conditions, but had poor ink adhesion because it did not have a surface layer containing a styrene copolymer (S). The single-layer sheets made of styrene copolymer (S) in the comparative examples (EC22-V) and (EC23-V) had good ink adhesion, but because the content of styrene monomer units in the laminated sheet was high, their laser cutting processability was poor under both normal power / normal speed conditions and high power / high speed conditions.

[0092] In Examples (E1-R) to (E4-R), (E7-R), (E8-R), and (E10-R), laminate sheets were obtained in the same manner as the Examples shown in Table 2, except that 50 mass% of the total raw materials for the base layer was replaced with a rework material made from pulverized laminate sheets obtained in the Examples shown in Table 2. In these Examples, laminate sheets were produced in which a base layer containing a methacrylic resin (M) was laminated on both sides thereof with surface layers containing a styrene copolymer (S), and the ratio of the total thickness of the surface layers to the total thickness of the laminate sheet was 0.1 to 8.0%. The laminated sheets obtained in these examples all had good ink adhesion. In these examples, the concentration of monomer units (specifically styrene units in these examples) derived from monomers with an explosion limit in air of 2.0% by volume or less in the laminate sheet was 6.0% by mass or less. All of the obtained laminate sheets had good laser cutting processability under both normal power / normal speed conditions and high power / high speed conditions.

[0093] The styrene copolymer (S) used in Examples (E1-R) to (E4-R) and (E8-R), especially Examples (E1-R) to (E4-R), had good compatibility with the methacrylic resin (M), and the haze value of the resulting laminate sheet and the 3.0 mm thick single-layer molded sheet pulverized from the resulting laminate sheet was 5% or less, and the transparency was good. In these examples, a laminate sheet with excellent sustainability that can be used as a rework material was obtained.

[0094] In the comparative examples (EC5-R), (EC6-R), (EC9-R), (EC11-R), and (EC12-R), laminate sheets were obtained in the same manner as the examples or comparative examples shown in Table 2, except that 50 mass% of the total raw materials for the base layer was replaced with a rework material consisting of the pulverized laminate sheets obtained in the examples or comparative examples shown in Table 2. The laminated sheets obtained in these examples all had good ink adhesion. In these examples, the concentration of monomer units (specifically styrene units in these examples) derived from monomers with an explosion limit in air of 2.0% by volume or less in the laminated sheet exceeded 6.0% by mass. All of the obtained laminated sheets had poor laser cutting processability, even under high-power and high-speed conditions.

[0095] The present invention is not limited to the above-described embodiments and examples, and appropriate design changes are possible without departing from the spirit of the present invention. [Explanation of symbols]

[0096] 1, 2 laminated sheet 11 Base material layer 21, 22, 23 surface layer

Claims

1. A laminated sheet having a base layer and a surface layer laminated on at least one surface of the base layer, the base layer contains a methacrylic resin (M) containing 80% by mass or more of methyl methacrylate units, the surface layer contains a styrene-based copolymer (S), A laminate sheet in which the concentration of units derived from a monomer having a lower explosion limit in air of 2.0% by volume or less is 6.0% by mass or less.

2. 2. The laminate sheet according to claim 1, wherein the ratio of the total thickness of said surface layer to the total thickness of said laminate sheet is 0.1 to 8.0%.

3. 2. The laminate sheet according to claim 1, wherein the styrene copolymer (S) is one or more styrene copolymers selected from the group consisting of methyl methacrylate-styrene copolymer (MS), acrylonitrile-styrene copolymer (AS), and styrene-maleic anhydride copolymer (SMA).

4. The styrene copolymer (S) is one or more styrene copolymers selected from the group consisting of acrylonitrile-styrene copolymers (AS) containing 75 to 95% by mass of styrene units and styrene-maleic anhydride copolymers (SMA) containing 60 to 95% by mass of styrene units. The laminate sheet according to claim 3.

5. 4. The laminate sheet according to claim 3, wherein a haze value of a 3.0 mm thick single-layer molded sheet made from the pulverized laminate sheet is 5% or less.

6. 2. The laminate sheet according to claim 1, wherein the content of the styrene-based monomer unit in the laminate sheet is 0.1 to 6.0% by mass.

7. 2. The laminate sheet according to claim 1, wherein the substrate layer is made of a methacrylic resin composition (MR) containing a methacrylic resin (M) and a styrene copolymer (S).

8. 2. The laminate sheet according to claim 1, wherein the content of the styrene-based monomer unit in the base layer is 0 to 10.0% by mass.

9. A laminate sheet as described in claim 7, wherein at least a portion of the total raw materials of the base material layer is a recycled resin composition (R) consisting of crushed material of the laminate sheet manufactured in the past or a processed product of the crushed material.

10. 2. The laminate sheet according to claim 1, wherein the total thickness of the laminate sheet is 1 to 10 mm.

11. 10. The laminate sheet of claim 1, which is suitable for inkjet printing and / or laser cutting.

12. A printed matter, wherein inkjet printing is performed on the surface layer of the laminate sheet according to any one of claims 1 to 11.

13. A molded article obtained by subjecting the laminate sheet according to any one of claims 1 to 11 to inkjet printing and laser cutting.

14. 8. The method for producing a laminate sheet according to claim 7, wherein the laminate sheet is co-extruded using a recycled resin composition (R) consisting of crushed material of the laminate sheet produced in the past or a processed product of the crushed material as at least a part of the total raw materials of the base material layer.

15. The method for producing a molded product according to claim 13, wherein the laminated sheet is cut using a laser processing machine having an output of 30 W or more.

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