Sheet for thermoforming, decorative sheet and molding using them

Abstract

To provide a sheet for thermoforming which achieves both moldability and hardness.SOLUTION: A sheet for thermoforming is formed by laminating at least three layers of a layer (A layer) containing a polycarbonate-based resin, a layer (B layer) containing an acrylic resin, and a layer (C layer) formed from an uncured product of an acrylate-based active energy ray-curable resin composition (composition C) in this order, further has a protective film peelable from the C layer provided on the C layer, and thermoforms the C layer in an uncured state, wherein a glass transition temperature (Tg) of the layer A is 100°C or higher and 145°C or lower, thickness of the layer A is within the range of 50 to 3,000 μm, and thickness of the layer B is within the range of 10 to 300 μm (excluding sheet for thermoforming having the C layer provided on both surface sides of the layer A).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a thermoforming sheet or decorative sheet that is suitably used in a method of integrating a sheet imparted with a design or function with a resin molded article by thermoforming in order to impart chemical resistance, scratch resistance, and design to the surface of the resin molded article, and to a molded article using these. [Background technology]

[0002] In recent years, the adoption of molded plastic parts in automobiles has been increasing due to the diversification of automobile designs and the demand for lighter vehicles. These molded plastic parts are required to have designs such as wood grain or metallic finishes, as well as functions such as chemical resistance and scratch resistance. To impart these designs and functions, a method has been proposed in which a sheet with a specific design or function, such as a decorative sheet, is integrated with the molded plastic part. Specific examples include the following two methods: (1) a method in which a sheet is pre-formed into a specific shape by thermoforming (vacuum forming, pressure forming, etc.), which is then placed in an injection mold and molten resin is injected into it to form an injection-molded product, which is simultaneously integrated with the preformed sheet; and (2) a method in which a sheet is thermoformed onto a pre-fabricated molded plastic part (three-dimensional surface decorative molding). Both of these methods (1) and (2) require the thermoforming of a sheet. The thermoforming sheet used has a hard coating layer to provide chemical resistance and scratch resistance, and the base sheet is required to be transparent so as not to interfere with the appearance of the design layer. Therefore, acrylic resins, polycarbonate resins, and polyester resins are generally used.

[0003] For example, Patent Document 1 discloses an example of an abrasion-resistant sheet having an ultraviolet-curable hard coat layer on a laminated sheet of a polycarbonate resin layer and an acrylic resin layer containing rubber particles. However, the hard coat layer, once cured, cannot follow three-dimensional molding, and when molding is attempted using the above methods (1) and (2), the hard coat layer cracks.

[0004] As a countermeasure against the above, Patent Document 2 discloses an example of a so-called two-stage curing method in which a laminated hard-coated film having an ultraviolet-curable hard-coat layer formed on a substrate film is cured with a weak ultraviolet exposure before three-dimensional molding, and then post-exposed after three-dimensional molding, thereby achieving both formability and surface hardness. Such two-stage curing raises concerns that the formability may vary depending on the state of curing in the first stage, and that the product life may be significantly shortened.

[0005] The thermoforming sheets used in methods (1) and (2) are primarily required to have the following properties. First, formability is essential. That is, sufficient extensibility to accommodate three-dimensional molding and the absence of cracks or other cosmetic defects when stretched are important. In particular, when high-temperature preheating is performed during molding, even if the sheet has good extensibility before heating, the preheating can cause the functional layer to harden, significantly degrading the extensibility. Second, surface hardness (pencil hardness, scratch resistance) is essential. When a thermoforming sheet is integrated with a resin molded product, the functional layer is placed on the outermost surface, which is necessary to ensure the surface functionality of the resin molded product. To achieve this, high surface hardness is required. However, there is generally a trade-off between the hardness and extensibility of the hard coat layer, and achieving both properties has traditionally been a challenge. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 5176749 [Patent Document 2] Japanese Patent Application Laid-Open No. 2012-210755 Summary of the Invention [Problem to be solved by the invention]

[0007] The object of the present invention is to provide a thermoforming sheet or decorative sheet that combines formability and hardness, and a molded article using the same. In particular, the object is to provide a thermoforming sheet or decorative sheet that is suitable for use in a method of integrating a sheet having chemical resistance and abrasion resistance with a resin molded article by thermoforming in order to impart these properties to the surface of the resin molded article, and a molded article using the same. [Means for solving the problem]

[0008] It has been discovered that the above-mentioned problems can be solved by a thermoforming sheet comprising at least three layers laminated in this order: a layer containing a specific polycarbonate-based resin (layer A), a layer containing an acrylic-based resin (layer B), and a layer formed from an uncured product of an acrylate-based active energy ray-curable resin composition (composition C) (layer C). That is, according to the present invention, the following configurations are provided.

[0009] 1. A thermoforming sheet comprising at least three layers laminated in this order: a layer containing a polycarbonate-based resin (layer A), a layer containing an acrylic-based resin (layer B), and a layer (layer C) formed from an uncured product of an acrylate-based active energy ray-curable resin composition (composition C), and further comprising a protective film on layer C that is peelable from layer C, wherein layer C is subjected to thermoforming in an uncured state, wherein layer A has a glass transition temperature (Tg) of 100°C or higher and 145°C or lower, layer A has a thickness in the range of 50 to 3000 μm, and layer B has a thickness in the range of 10 to 300 μm (excluding those having layers C on both surface sides of layer A). 2. The thermoforming sheet according to item 1 above, wherein the layer A contains a polyester-based thermoplastic elastomer, and the polyester-based thermoplastic elastomer is composed of hard segments consisting of polybutylene terephthalate units and soft segments consisting of polyester units having an aromatic dicarboxylic acid and an aliphatic dicarboxylic acid as the dicarboxylic acid component and a diol having 5 to 15 carbon atoms as the diol component. 3. The thermoforming sheet according to item 2 above, wherein the layer A contains 1 to 20 parts by weight of the polyester thermoplastic elastomer according to item 2 above, per 100 parts by weight of polycarbonate resin. 4. The thermoforming sheet according to any one of the above items 1 to 3, wherein the layer B does not substantially contain rubber particles. 5. The thermoforming sheet according to any one of items 1 to 4 above, wherein Layer C contains 1 to 5 parts by weight of a hindered amine compound per 100 parts by weight of the uncured acrylate-based active energy ray-curable resin composition (Composition C). 6. The thermoforming sheet according to any one of items 1 to 5 above, wherein the layer C is irradiated with active energy rays and cured, resulting in a cured layer having a surface with a pencil hardness of H or higher. 7. The thermoforming sheet according to any one of items 1 to 6 above, wherein a protective film is provided on the C layer, and the protective film is peelable from the C layer. 8. The thermoforming sheet according to any one of items 1 to 7 above, wherein the total thickness of the forming sheet is in the range of 0.05 mm or more and 3 mm or less. 9. A decorative sheet in which a decorative layer is formed on the thermoforming sheet according to any one of the preceding paragraphs 1 to 8, on the side of layer A opposite to the side of layers B and C. 10. A method for producing a molded body, comprising: forming a thermoforming sheet according to any one of items 1 to 8 above or a decorative sheet according to item 9 above into the shape of a mold cavity in advance, placing the sheet in the mold, and simultaneously molding a resin material to produce an integrated molded body; and then post-exposing the molded body to active energy rays. 11. A method for producing a molded body, comprising attaching a thermoforming sheet according to any one of items 1 to 8 above or a decorative sheet according to item 9 above to the cavity side of a mold under vacuum pressure, producing a molded body by integrating the sheet with a resin material at the same time, and then post-exposing the molded body to active energy rays. [Effects of the Invention]

[0010] The thermoforming sheet and decorative sheet of the present invention are thermoforming sheets and decorative sheets that combine formability and hardness, and are particularly suitable for use in techniques in which a sheet to which these functions have been imparted is integrated with a resin molded product by thermoforming in order to impart chemical resistance and abrasion resistance to the surface of the resin molded product. Resin molded articles using these sheets can be used for automobile interior materials, electrical appliances, cosmetic cases, interior and exterior building materials, etc., and the industrial effects they achieve are exceptional. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present invention will be described in detail below. (Layer containing polycarbonate resin (Layer A)) The polycarbonate resin used in the present invention is a polymer in which dihydroxy compounds are bonded by carbonate ester bonds, and is usually obtained by reacting a dihydroxy component with a carbonate precursor by interfacial polymerization or melt polymerization.

[0012] Representative examples of dihydroxy components include 2,2-bis(4-hydroxyphenyl)propane (commonly known as bisphenol A), 2,2-bis{(4-hydroxy-3-methyl)phenyl}propane (bisphenol C), 2,2-bis(4-hydroxyphenyl)butane, 2,2-bis(4-hydroxyphenyl)-3-methylbutane, 2,2-bis(4-hydroxyphenyl)-3,3-dimethylbutane, 2,2-bis(4-hydroxyphenyl)-4-methylpentane, and 1,1-bis(4-hydroxyphenyl)cyclohexane. Examples of suitable bisphenols include cyclohexane, 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, 1,1-bis(4-hydroxyphenyl)octane, 1,1-bis(4-hydroxyphenyl)decane, 9,9-bis{(4-hydroxy-3-methyl)phenyl}fluorene, 9,9-bis(4-hydroxyphenyl)fluorene, α,α'-bis(4-hydroxyphenyl)-m-diisopropylbenzene, isosorbide, 1,3-propanediol, 1,4-butanediol, and 1,6-hexanediol. These may be homopolymers using a single bisphenol or copolymers of two or more bisphenols. Bisphenol A is preferred from the viewpoints of physical properties and cost. In the present invention, polycarbonates in which 50 mol % or more of the bisphenol component is bisphenol A and / or bisphenol C are preferred, more preferably 70 mol % or more, and even more preferably 90 mol % or more are preferred.

[0013] Specific examples of polycarbonates include a homopolymer of bisphenol A, a homopolymer of bisphenol C, a copolymer of bisphenol A and bisphenol C, a copolymer of bisphenol A and 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, and a copolymer of bisphenol A and 9,9-bis{(4-hydroxy-3-methyl)phenyl}fluorene. A homopolymer of bisphenol A is most preferred.

[0014] Carbonate precursors that can be used include carbonyl halides, carbonate esters, and haloformates, and specific examples include phosgene, diphenyl carbonate, and dihaloformates of dihydric phenols.

[0015] When the dihydric dihydroxy compound and the carbonate precursor are reacted by interfacial polymerization or melt polymerization to produce a polycarbonate resin, a catalyst, a terminal terminator, an antioxidant for the dihydric phenol, etc. may be used as necessary. The polycarbonate resin may be a branched polycarbonate resin copolymerized with a trifunctional or higher polyfunctional aromatic compound, or a polyester carbonate resin copolymerized with an aromatic or aliphatic difunctional carboxylic acid, or a mixture of two or more of the obtained polycarbonate resins.

[0016] The molecular weight of the polycarbonate resin, expressed as a viscosity-average molecular weight, is preferably in the range of 13,000 to 40,000. If the molecular weight is lower than 13,000, the sheet may be brittle, and cracks and burrs may easily occur during thermoforming. On the other hand, if the molecular weight is higher than 40,000, the melt viscosity of the resin composition with a polyester-based thermoplastic elastomer may be too high, making melt film formation difficult. The molecular weight is more preferably 15,000 to 35,000, even more preferably 20,000 to 32,000, and particularly preferably 22,000 to 28,000. When the polycarbonate resin is a mixture of two or more types, the molecular weight refers to the molecular weight of the entire mixture. Here, the viscosity-average molecular weight is the specific viscosity (η) at 20°C of a solution in which 0.7 g of polycarbonate is dissolved in 100 mL of methylene chloride. sp ) was measured, and the viscosity average molecular weight (M) was calculated using the following formula: η sp / c=[η]+0.45×[η] 2 c [η]=1.23×10 -4 M 0.83 (where c=0.7g / dL, [η] is the intrinsic viscosity)

[0017] The glass transition temperature of the polycarbonate-based resin-containing layer (Layer A) of the present invention must be in the range of 100°C to 145°C, preferably 110°C to 140°C, and more preferably 120°C to 130°C. If the glass transition temperature is higher than this range, the thermoforming temperature must be increased, and heat exposure during thermoforming can initiate thermal radical polymerization in the layer (Layer C) formed from the uncured acrylate-based active energy ray-curable resin composition (Composition C), resulting in poor appearance such as cracks after molding. Furthermore, if the glass transition temperature is lower than this range, the appropriate molding temperature for thermoforming Layer A will be lower than the glass transition temperature of the acrylic resin-containing layer (Layer B) or the layer (Layer C) formed from the uncured acrylate-based active energy ray-curable resin composition (Composition C), making thermoforming impossible. Here, the glass transition point refers to a value measured by differential scanning calorimetry (DSC).

[0018] Although the method for adjusting the glass transition temperature of Layer A is not particularly limited, a method of blending a polyester thermoplastic elastomer with a polycarbonate resin is preferred to ensure the transparency of the thermoforming sheet. The polyester thermoplastic elastomer is preferably a multiblock copolymer composed of hard segments consisting of polybutylene terephthalate units and soft segments consisting of polyester units in which aromatic dicarboxylic acid and aliphatic dicarboxylic acid are used as dicarboxylic acid components and a diol having 5 to 15 carbon atoms is used as a diol component.

[0019] The hard segment composed of the polybutylene terephthalate unit has excellent compatibility with polycarbonate resin, is preferable in terms of transparency and thermoformability, and also has good properties in terms of strength, etc. Polybutylene terephthalate may contain other components as copolymerization components within a range that does not impair the effects of the present invention. The proportion of such copolymerization components is preferably 30 mol % or less, more preferably 20 mol % or less, and even more preferably 10 mol % or less, of the total components (100 mol %) of both the dicarboxylic acid component and the diol component. The intrinsic viscosity of the polymer that becomes the hard segment is preferably in the range of 0.2 to 2.0, more preferably 0.5 to 1.5.

[0020] The soft segment consisting of polyester units having an aromatic dicarboxylic acid and an aliphatic dicarboxylic acid as the dicarboxylic acid component and a diol having 5 to 15 carbon atoms as the diol component refers to a segment in which the melting point of the polymer formed from the segment is 100°C or lower, or which is liquid and amorphous at 100°C. The intrinsic viscosity of the polymer that becomes the soft segment is preferably in the range of 0.2 to 2.0, more preferably 0.5 to 1.5. The soft segment used is a soft segment consisting of polyester units having an aromatic dicarboxylic acid and / or an aliphatic carboxylic acid as the dicarboxylic acid component and a diol having 5 to 15 carbon atoms as the diol component (hereinafter sometimes referred to as "SS-1"). SS-1 is preferred because it provides extremely good transparency.

[0021] In order to obtain better transparency, the soft segment SS-1 preferably contains 60 to 99 mol% of aromatic dicarboxylic acid and 1 to 40 mol% of aliphatic dicarboxylic acid out of a total of 100 mol% of dicarboxylic acid components. It is more preferable that the aromatic dicarboxylic acid content is 70 to 95 mol% and the aliphatic dicarboxylic acid content is 5 to 30 mol%. It is even more preferable that the aromatic dicarboxylic acid content is 85 to 93 mol% and the aliphatic dicarboxylic acid content is 7 to 15 mol%. It is particularly preferable that the aromatic dicarboxylic acid content is 89 to 92 mol% and the aliphatic dicarboxylic acid content is 8 to 11 mol%.

[0022] The aromatic dicarboxylic acid of SS-1 is preferably at least one selected from the group consisting of terephthalic acid, isophthalic acid, 1,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-diphenylcarboxylic acid, bis(4-carboxyphenyl)methane, and bis(4-carboxyphenyl)sulfone, with terephthalic acid and isophthalic acid being more preferred, and isophthalic acid being particularly preferred from the viewpoint of reducing crystallinity.

[0023] As the aliphatic dicarboxylic acid of SS-1, straight-chain aliphatic dicarboxylic acids having 4 to 12 carbon atoms such as succinic acid, adipic acid, and sebacic acid are preferred, with sebacic acid being particularly preferred.

[0024] As the diol component having 5 to 15 carbon atoms in SS-1, linear aliphatic diols having 6 to 12 carbon atoms such as hexamethylene glycol, decamethylene glycol, 3-methylpentanediol, and 2-methyloctamethylenediol are more preferred, with hexamethylene glycol being particularly preferred.

[0025] SS-1 is particularly preferred because it has high compatibility with polycarbonate resins, can produce highly transparent products, and has good surface properties and transparency after thermoforming. More specifically, SS-1 is preferably a polyester composed of isophthalic acid, sebacic acid, and hexamethylene glycol.

[0026] In the present invention, the ratio of hard segments to soft segments in the polyester-based thermoplastic elastomer is preferably 20 to 70% by weight of hard segments and 80 to 30% by weight of soft segments, more preferably 20 to 40% by weight of hard segments and 80 to 60% by weight of soft segments, based on 100% by weight of the elastomer. The intrinsic viscosity of the polyester-based thermoplastic elastomer (measured in o-chlorophenol at 35°C) is preferably 0.6 or higher, more preferably 0.8 to 1.5, and even more preferably 0.8 to 1.2. An intrinsic viscosity lower than the above range is undesirable because it may result in a decrease in sheet strength.

[0027] In the present invention, it is preferable that 1 to 20 parts by weight of polyester thermoplastic elastomer is contained per 100 parts by weight of polycarbonate resin in Layer A. If the amount of polyester thermoplastic elastomer is less than 1 part by weight, the glass transition temperature of Layer A may exceed 145°C, and if it exceeds 20 parts by weight, the glass transition temperature of Layer A may fall below 100°C.

[0028] The thickness of Layer A is preferably in the range of 50 to 3000 μm, more preferably in the range of 100 to 2000 μm, further preferably in the range of 150 to 1500 μm, particularly preferably in the range of 200 to 1000 μm, and most preferably in the range of 250 to 500 μm.

[0029] Layer A of the present invention may contain various additives commonly used in each resin, such as heat stabilizers, antioxidants, UV absorbers, antistatic agents, dyes, etc. Furthermore, it may contain reinforcing fillers such as glass fibers, as long as the effects of the present invention are not impaired.

[0030] (Layer containing acrylic resin (Layer B)) In the present invention, the acrylic resin used for Layer B is preferably one mainly composed of a polymer of methacrylic acid ester or acrylic acid ester. When a resin other than an acrylic resin is used for Layer B, for example, a polycarbonate resin is undesirable because the surface hardness of the laminated film is low and the molded product is easily scratched. Furthermore, a PET resin is undesirable because it is prone to causing poor appearance due to uneven thickness. The acrylic resin is preferably a copolymer containing methyl methacrylate, preferably at 50 mol% or more, more preferably at 70 mol% or more, even more preferably at 80 mol% or more, and particularly preferably at 90 mol% or more.

[0031] Examples of other copolymerization components include ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate. Other ethylenically unsaturated monomers are also included. Specific examples include vinyl aromatic compounds such as styrene, α-methylstyrene, and vinyltoluene; diene compounds such as 1,3-butadiene and isoprene; alkenyl cyanide compounds such as acrylonitrile and methacrylonitrile; acrylic acid, methacrylic acid, maleic anhydride, and N-substituted maleimides. These may be used alone or in combination of two or more. The content of the copolymerization component is preferably 0 to 50% by weight, more preferably 0 to 30% by weight, and even more preferably 0 to 20% by weight. Acrylic resin production methods are generally broadly divided into emulsion polymerization, suspension polymerization, and continuous polymerization, and the acrylic resin used in the present invention may be produced by any of these polymerization methods. Layer B may also contain various additives such as general heat stabilizers, colorants, release agents, lubricants, antistatic agents, and matting agents.

[0032] Although rubber particles can be added to Layer B of the present invention, it is preferable that Layer B does not substantially contain rubber particles. Although adding rubber particles to an acrylic resin to improve toughness is a well-known and widely used technique, it is preferable that Layer B does not contain rubber particles from the viewpoint of ensuring transparency and surface hardness.

[0033] The thickness of Layer B is preferably in the range of 10 to 300 μm, more preferably in the range of 20 to 250 μm, further preferably in the range of 30 to 200 μm, particularly preferably in the range of 35 to 150 μm, and most preferably in the range of 40 to 100 μm.

[0034] (Layer (C layer) formed from uncured acrylate-based active energy ray-curable resin composition (composition C)) The uncured active energy ray-curable resin composition (composition C) constituting layer C of the present invention contains an acrylate resin such as an acrylate or urethane acrylate. The content is preferably in the range of 70 to 95 mass% of the total solid content of layer C. If the content is less than 70 mass%, the cohesive strength, chemical resistance, scratch resistance, optical properties, etc. of the coating film may be reduced. If the content exceeds 95 mass%, the initiation of photopolymerization may be delayed, resulting in poor productivity. The acrylate resin contained in the layer C in the present invention may be either an oligomer or a prepolymer, and is not particularly limited.

[0035] The glass transition temperature of the uncured acrylate resin composition (composition C) is preferably 30 to 150°C, more preferably 35 to 140°C, and particularly preferably 40 to 130°C. If an acrylate resin with a glass transition temperature of less than 30°C is used, the coating film in the uncured state after heat drying may be tacky, and blocking may occur easily when the composition is wound into a roll. If the glass transition temperature is higher than 150°C, sufficient heat may not be applied during molding, which may result in cracking.

[0036] Furthermore, it is preferable that the pencil hardness of the cured layer obtained by irradiating an uncured acrylate resin composition (composition C) with active energy rays such as ultraviolet rays and curing it is H or higher. By setting the pencil hardness within this range, there is an advantage in that abrasion resistance is improved. When the pencil hardness is H or higher, scratch resistance is sufficient.

[0037] Here, the pencil hardness is the value measured by applying an uncured acrylate resin composition (composition C) to a sheet and drying the sheet with an integrated light dose of 1000 mJ / cm2, as will be described later in the Examples. 2 The coating is irradiated with ultraviolet light at 1000 W ...

[0038] In the present invention, a photopolymerization initiator can be contained in the C layer. By containing a photopolymerization initiator, the polymerization and curing reaction of the hard coat layer by light (ultraviolet light) irradiation can be carried out in a short time. Examples of photopolymerization initiators include benzophenone, benzil, Michler's ketone, 2-chlorothioxanthone, 2,4-diethylthioxanthone, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-diethoxyacetophenone, benzil dimethyl ketal, 2,2-dimethoxy-1,2-diphenylethan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1-[4-(methylthio)] Examples of suitable hydroxybenzoates include 1-[4-(2-hydroxyethoxy)-phenyl]-2-morpholinopropanone-1, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, bis(cyclopentadienyl)-bis(2,6-difluoro-3-(pyr-1-yl)titanium, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1, and 2,4,6-trimethylbenzoyldiphenylphosphine oxide. These compounds may be used alone or in combination.

[0039] The amount of photopolymerization initiator contained in the solid content of Layer C is preferably 0.01 to 10 mass % of the total solid content of Layer C, and more preferably 0.1 to 5 mass %. If the content of photopolymerization initiator is less than 0.01 mass %, the photocurability may be reduced, while if it is incorporated in an amount exceeding 10 mass %, coloration of Layer C may occur, and the progress of the photocuring reaction may not change, which may be economically disadvantageous. It is also possible to add various known dyes and sensitizers to improve the photocurability.

[0040] The thickness of the C layer is preferably in the range of 1 to 50 μm, more preferably in the range of 2 to 30 μm, further preferably in the range of 2.5 to 20 μm, and particularly preferably in the range of 3 to 10 μm. Depending on the circumstances, additives such as leveling agents, antifoaming agents, antifouling agents and other surfactants, surface modifiers and other additives, and organic fillers, inorganic fillers and other fillers can be added to the C layer.

[0041] (Hindered amine compounds) Layer C of the present invention preferably contains a hindered amine compound. By containing a hindered amine compound, thermal radicals generated by heat exposure during thermoforming can be captured, thereby suppressing thermal radical polymerization. Furthermore, from the viewpoint of effectively exerting the effects of the present invention, the content of the hindered amine compound is preferably 1 to 5 parts by weight per 100 parts by weight of the uncured acrylate-based active energy ray-curable resin composition (composition C). If the content is less than 1 part by weight, the thermal radical scavenging effect may not be obtained, and if it exceeds 5 parts by weight, curing of Layer C may be inhibited.

[0042] (protective film) In the thermoforming sheet of the present invention, it is preferable to laminate a protective film on the surface of Layer C to protect the uncrosslinked Layer C before curing from contamination and scratches. The protective film is not particularly limited, but polyethylene film, polypropylene film, polyethylene terephthalate film, etc. can be preferably used. After laminating the protective film, in consideration of the heat exposure in the process of forming a decorative layer by printing or the like on the side of Layer A of the thermoforming sheet of the present invention opposite to the Layers B and C, heat-resistant polypropylene film and polyethylene terephthalate film are more preferred.

[0043] (Method of manufacturing thermoforming sheets) The laminated sheet of Layer A and Layer B that constitutes the thermoforming sheet of the present invention can be produced by co-extrusion of molding material A for Layer A and molding material B for Layer B. Co-extrusion is a method of obtaining a multilayer sheet by melt-extruding molding material A and molding material B using separate extruders and laminating them using a feed block or multi-manifold die, and it is possible to control the total thickness and thickness composition of the resulting laminated sheet by adjusting the extrusion rate, film-forming speed, die lip gap, etc. of each extruder.

[0044] Laminated sheets are formed by pressing molten resin against a roll or belt. Furthermore, by using a metal roll to sandwich the molten resin before it cools and solidifies, a mirror-like metal finish can be transferred, improving the surface appearance of the laminated sheet. Examples of elastic metal rolls include those equipped with a shaft roll and a cylindrical metal film that is arranged to cover the outer surface of the shaft roll and contacts the molten resin. Temperature-controlled fluids such as water or oil are sealed between the shaft roll and the metal film, and those equipped with a metal belt wrapped around the surface of a rubber roll. Among these, elastic metal rolls with a metal belt wrapped around two or more rolls sandwich the molten resin over a wider arc-shaped surface, allowing for cooling while minimizing residual stress within the resin.

[0045] Coating is commonly used to laminate the C layer constituting the thermoforming sheet of the present invention onto the laminate sheet of the A and B layers. The coating method is not particularly limited, but methods that allow for easy adjustment of coating thickness, such as gravure coating, microgravure coating, fountain bar coating, slide die coating, and slot die coating, are possible. In the coating process, a coating prepared by dissolving and dispersing an acrylate-based active energy ray-curable resin composition (composition C) and, if necessary, a hindered amine compound, an initiator, and other additives in an appropriate solvent, is applied to the laminate sheet and dried to form the C layer. The solvent can be selected appropriately depending on the solubility of composition C, and should be one that can uniformly dissolve or disperse at least the solid components (resin, polymerization initiator, and other additives). Examples of such solvents include ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, etc.), ethers (dioxane, tetrahydrofuran, etc.), aliphatic hydrocarbons (hexane, etc.), alicyclic hydrocarbons (cyclohexane, etc.), aromatic hydrocarbons (toluene, xylene, etc.), halogenated carbons (dichloromethane, dichloroethane, etc.), esters (methyl acetate, ethyl acetate, butyl acetate, etc.), alcohols (methanol, ethanol, isopropanol, butanol, cyclohexanol, etc.), cellosolves (methyl cellosolve, ethyl cellosolve, etc.), cellosolve acetates, sulfoxides, amides, etc. The solvents may be used alone or in combination.

[0046] The thickness of the thermoforming sheet of the present invention is not particularly limited, but is preferably 0.05 mm to 3 mm, more preferably 0.1 mm to 2.5 mm, even more preferably 0.15 mm to 2 mm, and particularly preferably 0.2 mm to 1 mm.

[0047] (Method of manufacturing decorative sheet) The thermoforming sheet of the present invention can be provided with a decorative layer by printing or the like on the side of Layer A opposite Layer B. Methods for forming the decorative layer include forming a design layer by printing, forming a thin film layer of metal or metal oxide, and the like, and these may be used in combination. Printing methods for forming the design layer include known printing methods such as gravure printing, lithographic printing, flexographic printing, dry offset printing, pad printing, and screen printing, depending on the product shape and printing application. Methods for forming a thin film layer of metal or metal oxide include vapor deposition, thermal spraying, and plating. Specific vapor deposition methods include vacuum vapor deposition, sputtering, ion plating, thermal CVD, plasma CVD, and photo CVD. Thermal spraying methods include atmospheric pressure plasma spraying and low-pressure plasma spraying. Plating methods include electroless plating, hot-dip plating, and electroplating. In the thermoforming sheet and the decorative sheet, it is preferable that Layer C is the outermost layer, since it has excellent properties such as hardness.

[0048] (Method of manufacturing a molded body) The thermoforming sheet or decorative sheet of the present invention can be used to produce molded articles, such as automotive interior materials, automotive indicator panels, electrical appliances, cosmetic cases, interior and exterior building materials, cases for various devices, products, and miscellaneous items, switches, keys, keypads, handles, levers, buttons, and housings and exterior parts for home appliances and AV equipment such as personal computers, mobile phones, and mobile devices. The molded article can be obtained by carrying out various conventional molding processes using the thermoforming sheet or the decorative sheet.

[0049] As a molding method for the molded body, an insert molding method is an in-mold decoration method for injection molding, in which a thermoforming sheet or decorative sheet that has been shaped in advance by vacuum forming, compressed air forming, etc. to fit the shape of the injection molding mold cavity is set in the mold, and molten resin is injected into it, and the thermoforming sheet or decorative sheet is welded to the resin molded product and integrated with it at the same time to obtain the molded body.

[0050] Another molding method for a molded body is to attach a thermoforming sheet or a decorative sheet to the mold cavity side under vacuum pressure, inject molten resin into it, and apply heat and pressure to bond the thermoforming sheet or the decorative sheet to the resin molded product to obtain a molded body.

[0051] Further examples include lamination by vacuum forming or pressure forming. Various methods can be used to heat the decorative forming film during thermoforming, such as infrared heaters, electric heaters, high-frequency induction, halogen lamps, microwaves, high-temperature induction heaters (steam, etc.), and lasers.

[0052] The molded article thus produced preferably has the C layer positioned at the outermost surface. The molded article is cooled or allowed to cool, and then the C layer is cured by irradiating it with radiation (ultraviolet light, visible light, infrared light, or electron beam). This radiation may be polarized or unpolarized. Ultraviolet light is particularly preferred from the viewpoints of equipment costs, safety, running costs, etc. When curing is performed by ultraviolet irradiation, a photopolymerization initiator must be added. Preferred examples of ultraviolet energy ray sources include high-pressure mercury lamps, halogen lamps, xenon lamps, metal halide lamps, nitrogen lasers, electron beam accelerators, and radioactive elements. The irradiation dose of the energy ray source is 100 to 5,000 mJ / cm as the cumulative exposure dose at an ultraviolet wavelength of 365 nm. 2 The range is preferably 300 to 3,000 mJ / cm 2 More preferably, the irradiation dose is 100 mJ / cm. 2 If the dose is less than 5,000 mJ / cm, the curing may be insufficient and the hardness may decrease. 2 If the oxygen concentration exceeds 100%, the C layer may become colored and transparency may decrease. The oxygen concentration during radiation exposure is preferably 5% or less, more preferably 3% or less, and particularly preferably 2% or less. In an oxygen-free or low-concentration atmosphere, the gas contained other than oxygen is preferably an inert gas. Examples of inert gases include nitrogen, helium, neon, and argon. [Example]

[0053] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Physical properties measured in the examples and comparative examples were measured by the following methods.

[0054] (glass transition temperature) Using a 2920 DSC manufactured by TA Instruments, measurements were taken at a temperature rise rate of 20°C / min, and the drop point was determined.

[0055] (Total thickness of thermoforming sheet) The value is the value at the center in the width direction of the sheet measured with an electronic micro film thickness meter manufactured by Anritsu Corp. The width direction of the sheet refers to the direction perpendicular to the sheet flow direction during film formation.

[0056] (Pencil hardness) The cumulative light intensity was 1000 mJ / cm from the C layer side of the thermoforming sheet. 2 The coating was cured by irradiating it with ultraviolet light at 100°C to prepare a test piece, and the pencil hardness of the coating was measured in accordance with JIS K5600-5-4-1999.

[0057] (Moldability) Using a biaxial stretching tester (manufactured by Toyo Seiki Seisakusho), the thermoforming sheet was preheated for 1 minute at a temperature of (glass transition temperature + 20)°C of Layer A, and then stretched at the same temperature to a stretch ratio of 1.3 times. The appearance of the sheet was evaluated using the following criteria. ○: No cracks or cloudiness observed △: Weak cracks or slight cloudiness are observed ×: Cracks or cloudiness are observed

[0058] [Preparation Example 1] (Production of polyester-based thermoplastic elastomer) 100 parts by weight of dimethyl isophthalate, 13 parts by weight of dimethyl sebacate, and 80 parts by weight of hexamethylene glycol were transesterified using dibutyltin diacetate as a catalyst, followed by polycondensation under reduced pressure to obtain an amorphous polyester (soft segment) with an intrinsic viscosity of 1.06 and no endothermic peak due to crystalline melting as measured by DSC. 32 parts by weight of polybutylene terephthalate pellets (hard segment) with an intrinsic viscosity of 0.98 were added to 100 parts by weight of the polyester, and the mixture was reacted at 240°C for 45 minutes. The reaction was then terminated by the addition of 0.03 parts by weight of phenylphosphonic acid. The resulting polymer had a melting point of 190°C and an intrinsic viscosity of 0.93.

[0059] [Example 1] (Molding material A) Polycarbonate resin pellets (Panlite L1250WP (bisphenol A homopolycarbonate resin (PC-A) with a viscosity average molecular weight of 23,900) manufactured by Teijin Limited) and the thermoplastic elastomer obtained in the above Preparation Example were each pre-dried and mixed in a V-blender so that 100 parts by weight of the polycarbonate resin pellets were mixed with 1 part by weight of the thermoplastic elastomer. The mixture was then extruded into pellets using a twin-screw extruder at a cylinder temperature of 260°C, yielding molding material A for layer A. The glass transition temperature of molding material A was 145°C.

[0060] (Molding material B) As molding material B for layer B, an acrylic resin (Acrypet VH-001 manufactured by Mitsubishi Rayon Co., Ltd., an acrylic resin obtained by copolymerizing 95 mol % of methyl methacrylate and 5 mol % of methyl acrylate) was prepared.

[0061] (coextrusion) Molding materials A and B were extruded from a 650 mm wide T-die using a feed block method with a single screw extruder having a screw diameter of 40 mm, with a cylinder temperature of 260°C (molding material A), 250°C (molding material B), and a screw rotation speed of 11 rpm (molding material A), and 109 rpm (molding material B). The molten resin was then compressed between a metal roll and a metal sleeve roll and cooled, after which the edges were trimmed and the sheet was wound up at a winding speed of 10.3 m / min to produce a 400 mm wide laminated sheet with a two-layer structure of A layer / B layer (A layer 440 μm, B layer 60 μm).

[0062] (Paint adjustment) The paint to form layer C was prepared by diluting 100 parts by weight of urethane acrylate ultraviolet-curing resin "Folseed No. 371C (trade name)" (solid content 40%, manufactured by Chugoku Paint Co., Ltd.), 5 parts by weight of Irgacure 184 (photopolymerization initiator, manufactured by Chiba Specialty Chemicals Co., Ltd.), and 5 parts by weight of hindered amine compound TINUVIN 292 (trade name)" (manufactured by BASF Ltd.) with methyl isobutyl ketone until the solid content concentration of the ultraviolet-curing resin in the paint reached 30%, and then thoroughly stirring.

[0063] (Coating) The paint for forming the above-mentioned C layer was applied to the B layer side of the laminated sheet of A and B layers using a bar coater (#8), and then hot air dried in a drying oven at 80°C for 1 minute to form a C layer with a coating thickness of 5 μm.A polypropylene protective film (manufactured by Oji F-Tex Co., Ltd.) was then laminated on top of the C layer to create a thermoforming sheet with a thickness of 0.5 mm.The various evaluation results are shown in Table 1.

[0064] [Example 2] A thermoforming sheet was prepared in the same manner as in Example 1, except that the content of the polyester-based thermoplastic elastomer, the thickness of the laminated sheet, and the content of the hindered amine compound were changed as shown in Table 1. The results of various evaluations are shown in Table 1.

[0065] [Example 3] A thermoforming sheet was prepared in the same manner as in Example 1, except that the content of the polyester-based thermoplastic elastomer, the thickness of the laminated sheet, and the content of the hindered amine compound were changed as shown in Table 1. The results of various evaluations are shown in Table 1.

[0066] [Example 4] A thermoforming sheet was prepared in the same manner as in Example 1, except that the content of the polyester-based thermoplastic elastomer, the thickness of the laminated sheet, and the content of the hindered amine compound were changed as shown in Table 1. The results of various evaluations are shown in Table 1.

[0067] [Example 5] A thermoforming sheet was prepared in the same manner as in Example 1, except that the content of the polyester thermoplastic elastomer and the content of the hindered amine compound were changed as shown in Table 1. The results of various evaluations are shown in Table 1.

[0068] [Example 6] Molding material B contained 5 parts by weight of rubber particles produced by emulsion polymerization per 100 parts by weight of acrylic resin. The innermost layer was a rigid polymer obtained by polymerization of monomers consisting of 93.8% methyl methacrylate, 6% methyl acrylate, and 0.2% allyl methacrylate; the middle layer was an elastomeric polymer obtained by polymerization of monomers consisting of 81% butyl acrylate, 17% styrene, and 2% allyl methacrylate; and the outermost layer was a rigid polymer obtained by polymerization of monomers consisting of 94% methyl methacrylate and 6% methyl acrylate. Thermoforming sheets were prepared in the same manner as in Example 1, except that the content of polyester-based thermoplastic elastomer and the thickness of the laminated sheet were changed as shown in Table 1. Various evaluation results are shown in Table 1.

[0069] [Example 7] A thermoforming sheet was prepared in the same manner as in Example 1, except that the thickness of the laminated sheet was changed as shown in Table 1. The results of various evaluations are shown in Table 1.

[0070] [Example 8] A thermoforming sheet was prepared in the same manner as in Example 1, except that the content of the polyester-based thermoplastic elastomer, the thickness of the laminated sheet, and the content of the hindered amine compound were changed as shown in Table 1. The results of various evaluations are shown in Table 1.

[0071] [Example 9] A thermoforming sheet was prepared in the same manner as in Example 1, except that the thickness of the laminated sheet and the content of the hindered amine compound were changed as shown in Table 1. The results of various evaluations are shown in Table 1.

[0072] [Example 10] A thermoforming sheet was prepared in the same manner as in Example 1, except that the content of the polyester-based thermoplastic elastomer, the thickness of the laminated sheet, and the content of the hindered amine compound were changed as shown in Table 1. The results of various evaluations are shown in Table 1.

[0073] [Example 11] When producing polycarbonate resin pellets for molding material A, 2,2-bis{(4-hydroxy-3-methyl)phenyl}propane (commonly known as bisphenol C; PC-C) was used instead of 2,2-bis(4-hydroxyphenyl)propane (commonly known as bisphenol A). A thermoforming sheet was produced in the same manner as in Example 1, except that the content of polyester-based thermoplastic elastomer, the thickness of the laminated sheet, and the content of the hindered amine compound were changed as shown in Table 1. The results of various evaluations are shown in Table 1.

[0074] [Example 12] After forming Layer C, no protective film was attached. A thermoforming sheet was prepared in the same manner as in Example 1, except that the content of the polyester thermoplastic elastomer, the thickness of the laminated sheet, and the content of the hindered amine compound were changed as shown in Table 1. The results of various evaluations are shown in Table 1.

[0075] [Comparative Example 1] No polyester-based thermoplastic elastomer was added to molding material A. A thermoforming sheet was prepared in the same manner as in Example 1, except that the thickness of the laminated sheet was changed as shown in Table 1. The results of various evaluations are shown in Table 2.

[0076] Comparative Example 2 A thermoforming sheet was prepared in the same manner as in Example 1, except that the content of the polyester-based thermoplastic elastomer, the thickness of the laminated sheet, and the content of the hindered amine compound were changed as shown in Table 1. The results of various evaluations are shown in Table 2.

[0077] Comparative Example 3 Instead of the urethane acrylate UV-curable resin "Folseed No. 371C," the resin composition for Layer C was replaced with an isopropanol solution of Tosguard 510 (manufactured by Momentive Performance Materials, Inc.), primarily composed of trifunctional and tetrafunctional alkoxysilanes. The resulting solution was then dried with hot air at 80°C for 1 minute. Furthermore, 5 parts by weight of emulsion-polymerized rubber particles were mixed with 100 parts by weight of acrylic resin into molding material B. The innermost layer was a hard polymer obtained by polymerization of monomers consisting of 93.8% methyl methacrylate, 6% methyl acrylate, and 0.2% allyl methacrylate; the middle layer was an elastomeric polymer obtained by polymerization of monomers consisting of 81% butyl acrylate, 17% styrene, and 2% allyl methacrylate; and the outermost layer was a hard polymer obtained by polymerization of monomers consisting of 94% methyl methacrylate and 6% methyl acrylate. Furthermore, a thermoforming sheet was prepared in the same manner as in Example 1, except that the thickness of the laminated sheet and the content of the hindered amine compound were changed as shown in Table 1. The results of various evaluations are shown in Table 2.

[0078] [Table 1]

[0079] [Table 2] [Industrial Applicability]

[0080] The thermoforming sheet and decorative sheet of the present invention have excellent formability and hardness, and molded articles using the thermoforming sheet and decorative sheet are useful as automotive interior materials, automotive indicator panels, electrical appliances, cosmetic cases, interior and exterior building materials, cases for various devices, products, and miscellaneous items, switches, keys, keypads, handles, levers, buttons, and housings and exterior parts for home appliances and AV equipment such as personal computers, mobile phones, and mobile devices.

Claims

1. The thermoforming sheet comprises at least three layers laminated in this order: a layer containing a polycarbonate-based resin (Layer A), a layer containing an acrylic-based resin (Layer B), and a layer (Layer C) formed from an uncured product of an acrylate-based active energy ray-curable resin composition (Composition C); and further comprises a protective film on Layer C that is peelable from Layer C, and Layer C is subjected to thermoforming in an uncured state; Layer A has a glass transition temperature (Tg) of 100°C or higher and 145°C or lower; Layer A has a thickness in the range of 50 to 3,000 μm; and Layer B has a thickness in the range of 10 to 300 μm (excluding thermoforming sheets having Layer C on both surface sides of Layer A).

2. The thermoforming sheet according to claim 1, wherein the layer A contains a polyester-based thermoplastic elastomer, and the polyester-based thermoplastic elastomer is composed of hard segments consisting of polybutylene terephthalate units and soft segments consisting of polyester units having an aromatic dicarboxylic acid and an aliphatic dicarboxylic acid as dicarboxylic acid components and a diol having 5 to 15 carbon atoms as a diol component.

3. 3. The thermoforming sheet according to claim 2, wherein the layer A contains 1 to 20 parts by weight of the polyester thermoplastic elastomer according to claim 2 relative to 100 parts by weight of a polycarbonate resin.

4. The thermoforming sheet according to any one of claims 1 to 3, wherein the layer B is substantially free of rubber particles.

5. The thermoforming sheet according to any one of claims 1 to 4, wherein Layer C contains 1 to 5 parts by weight of a hindered amine compound per 100 parts by weight of an uncured acrylate-based active energy ray-curable resin composition (composition C).

6. The thermoforming sheet according to any one of claims 1 to 5, wherein the surface of the cured layer obtained by irradiating the C layer with active energy rays and curing it has a pencil hardness of H or higher.

7. The thermoforming sheet according to any one of claims 1 to 6, wherein the total thickness of the forming sheet is in the range of 0.05 mm or more and 3 mm or less.

8. A decorative sheet comprising the thermoforming sheet according to any one of claims 1 to 7, wherein a decorative layer is formed on the side of layer A opposite to the side of layers B and C.

Images