Thermoforming sheets, decorative sheets, and molded articles using the same

Abstract

To provide a thermoforming sheet that achieves both moldability and hardness. [Solution] A thermoforming sheet for use in a mold decoration method in injection molding, comprising at least three layers in this order: a layer containing a polycarbonate resin (layer A), a layer containing an acrylic resin (layer B), and a layer formed from the uncured material of a urethane acrylate-based active energy ray curable resin composition (composition C) (layer C), further comprising a protective film that can be peeled off from layer C, wherein the glass transition temperature (Tg) of layer A is 100°C or more and 145°C or less.

Description

[Technical Field]

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

[0002] In recent years, the increasing diversity of automotive designs and the demand for lighter vehicles have led to a rise in the use of resin molded parts in automobiles. These resin molded parts require designs such as wood grain and metallic finishes, as well as functions such as chemical resistance and scratch resistance. As a method for adding design and function, a method has been proposed in which sheets with specific designs or functions, such as decorative sheets, are integrated with the resin molded product. Two specific examples of this method are as follows: (1) A method in which a sheet is pre-formed into a specific shape by thermoforming (vacuum forming, pressure forming, etc.), set in an injection molding die, and molten resin is injected to form an injection molded body while simultaneously integrating it with the pre-formed sheet; (2) A method in which a sheet is pre-made resin molded product is covered with a sheet by thermoforming (three-dimensional surface decorative molding). Both of these methods (1) and (2) require the thermoforming of a sheet, and the thermoforming sheets used have a hard coat 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, so acrylic resins, polycarbonate resins, and polyester resins are generally used.

[0003] For example, Patent Document 1 discloses an example of a scratch-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 the hard coat layer cracks when molded using the methods described in (1) and (2) above.

[0004] As a countermeasure to the above, Patent Document 2 discloses an example of so-called two-stage curing in a laminated hard coat film in which an ultraviolet-curable hard coat layer is formed on a base film, in which the hard coat layer is cured with a weak amount of ultraviolet exposure before three-dimensional molding, and then post-exposure is performed after three-dimensional molding to achieve both moldability and surface hardness. However, there are concerns that such two-stage curing may result in variations in moldability depending on the state of curing in the first stage, or that the product life may be significantly deteriorated.

[0005] The thermoforming sheets used in methods (1) and (2) primarily require the following characteristics. First, moldability is required. That is, it is important that they have sufficient elongation to follow three-dimensional molding and that they do not develop surface defects such as cracks when stretched. In particular, when high-temperature preheating is performed during molding, even if they have good elongation before heating, preheating causes the functional layer to harden, leading to a significant deterioration in elongation. Second, surface hardness (pencil hardness, scratch resistance) is required. When thermoforming sheets are integrated with resin molded products, the functional layer is placed on the outermost surface, and the surface function of the resin molded product is required. For this purpose, high surface hardness is required, but generally there is a trade-off relationship between the hardness of the hard coat layer and elongation, and balancing the characteristics of both has been a challenge in the past. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Patent No. 5176749 [Patent Document 2] Japanese Patent Publication No. 2012-210755 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] The object of the present invention is to provide thermoforming sheets, decorative sheets, and molded articles using these that achieve both moldability and hardness. In particular, the object is to provide thermoforming sheets, decorative sheets, and molded articles using these that are suitable for use in a method of integrating sheets with chemical resistance and scratch resistance on the surface of a resin molded article by thermoforming. [Means for solving the problem]

[0008] We have found that the above problem can be solved by a thermoforming sheet comprising at least three layers laminated in at least this order: a layer containing a specific polycarbonate resin (layer A), a layer containing an acrylic resin (layer B), and a layer formed from the uncured material of an acrylate-based active energy ray curable resin composition (composition C) (layer C). In other words, the present invention provides the following configuration.

[0009] 1. A thermoformable sheet comprising at least three layers laminated in this order: a layer containing a polycarbonate resin (layer A), a layer containing an acrylic resin (layer B), and a layer formed from the uncured material of an acrylate-based active energy ray curable resin composition (composition C) (layer C), wherein the glass transition temperature (Tg) of layer A is 100°C or higher and 145°C or lower. 2. The thermoforming sheet according to paragraph 1, wherein the A layer contains a polyester thermoplastic elastomer, and the polyester thermoplastic elastomer is composed of a hard segment made of polybutylene terephthalate units and a soft segment made of polyester units having aromatic dicarboxylic acids and aliphatic dicarboxylic acids as dicarboxylic acid components and diols having 5 to 15 carbon atoms as diol components. 3. The thermoforming sheet described in paragraph 2, wherein the A layer contains 1 to 20 parts by weight of the polyester thermoplastic elastomer described in paragraph 2, per 100 parts by weight of the polycarbonate resin. 4. The thermoforming sheet according to any one of items 1 to 3 above, wherein the B layer substantially does not contain rubber particles. 5. The C layer is a thermoforming sheet according to any one of items 1 to 4 above, containing 1 to 5 parts by weight of a hindered amine compound per 100 parts by weight of uncured acrylate-based active energy ray curable resin composition (composition C). 6. A thermoforming sheet according to any one of items 1 to 5 above, wherein the pencil hardness of the surface of the hardened layer obtained by irradiating the C layer with active energy rays and hardening it is H or higher. 7. A thermoforming sheet according to any one of paragraphs 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. A thermoforming sheet according to any of items 1 to 7 above, wherein the total thickness of the molding sheet is in the range of 0.05 mm or more and 3 mm or less. 9. A decorative sheet having a decorative layer formed on the side opposite to the B and C layers of the A layer of the thermoforming sheet described in any of items 1 to 8 above. 10. A method for manufacturing a molded article, characterized by first shaping a thermoforming sheet described in paragraphs 1 to 8 above or a decorative sheet described in paragraph 9 above into the shape of a mold cavity, then placing it in a mold, and integrating it with the resin material at the same time as molding to produce a molded article, and then performing post-exposure with active energy rays. 11. A method for manufacturing a molded article, characterized by attaching the thermoforming sheet described in paragraphs 1 to 8 above or the decorative sheet described in paragraph 9 above to the mold cavity side under vacuum pressure, creating a molded article that is integrated with the resin material at the same time as molding, and then performing post-exposure with active energy rays. [Effects of the Invention]

[0010] The thermoforming sheets and decorative sheets of the present invention are thermoforming sheets and decorative sheets that achieve both moldability and hardness, and are particularly suitable for use in a method of integrating sheets with resin molded products by thermoforming in order to impart chemical resistance and scratch resistance to the surface of resin molded products. Resin molded products using these sheets can be used in automotive interior materials, electrical appliances, cosmetic cases, building interior and exterior parts, and the industrial effects they provide are exceptional. [Modes for carrying out 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 linked by carbonate ester bonds, and is usually obtained by reacting the dihydroxy component with a carbonate precursor by interfacial polymerization or melt polymerization.

[0012] Typical examples of dihydroxy compounds 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)cyclohexyl Examples include xane, 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, 1,6-hexanediol, etc. These can be homopolymers using one of these compounds alone, or copolymers obtained by copolymerizing two or more of them. Bisphenol A is preferred from a physical property and cost standpoint. 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.

[0013] Specific polycarbonates include homopolymers of bisphenol A, homopolymers of bisphenol C, binary copolymers of bisphenol A and bisphenol C, binary copolymers of bisphenol A and 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, binary copolymers of bisphenol A and 9,9-bis{(4-hydroxy-3-methyl)phenyl}fluorene, and the like. The homopolymer of bisphenol A is most preferred.

[0014] As the carbonate precursor, carbonyl halide, carbonate ester, haloformate, or the like is used. Specifically, phosgene, diphenyl carbonate, or dihaloformate of a dihydric phenol can be mentioned.

[0015] When producing a polycarbonate resin by reacting the above dihydric dihydroxy compound and carbonate precursor by an interfacial polymerization method or a melt polymerization method, a catalyst, a terminal stopper, an antioxidant for the dihydric phenol, or the like may be used as necessary. The polycarbonate resin may also be a branched polycarbonate resin copolymerized with a polyfunctional aromatic compound having three or more functional groups, 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 is preferably in the range of 13,000 to 40,000, expressed as the viscosity average molecular weight. If the molecular weight is lower than 13,000, the sheet becomes brittle, and cracks and burrs may easily occur during thermoforming. If it is higher than 40,000, the melt viscosity of the resin composition with the polyester-based thermoplastic elastomer becomes too high, and melt film formation may become 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 kinds, it represents the molecular weight of the whole mixture. Here, the viscosity average molecular weight is the value obtained by measuring the specific viscosity (η sp ) of a solution prepared by dissolving 0.7 g of polycarbonate in 100 mL of methylene chloride at 20 °C and calculating the viscosity average molecular weight (M) from the following formula. η sp / c = [η] + 0.45 × [η] 2 c [η] = 1.23 × 10 -4 M 0.83 (where c = 0.7 g / dL and [η] is the intrinsic viscosity)

[0017] The glass transition temperature of the layer (layer A) containing the polycarbonate resin of the present invention needs to be in the range of 100 °C or higher and 145 °C or lower, preferably 110 °C or higher and 140 °C or lower, more preferably 120 °C or higher and 130 °C or lower. If the glass transition temperature is higher than the above range, it is necessary to increase the thermoforming temperature, and the thermal radical polymerization of the layer (layer C) formed from the uncured product of the acrylate-based active energy ray curable resin composition (composition C) may start due to the heat during thermoforming, resulting in appearance defects such as cracks after forming. Also, if the glass transition temperature is lower than the above range, the appropriate forming temperature for thermoforming layer A will be lower than the glass transition temperature of the layer (layer B) containing the acrylic resin or the layer (layer C) formed from the uncured product of the acrylate-based active energy ray curable resin composition (composition C), and thermoforming will become impossible. Here, the glass transition point refers to the value measured by the differential scanning calorimetry (DSC) method.

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

[0019] The hard segments made of polybutylene terephthalate units have excellent compatibility with polycarbonate resin, are preferable in terms of transparency and thermoformability, and also have good properties in terms of strength and other aspects. Polybutylene terephthalate may contain other components as copolymer components as long as it does not impair the effects of the present invention. The proportion of such copolymer components is preferably 30 mol% or less, more preferably 20 mol% or less, and even more preferably 10 mol% or less, for both the dicarboxylic acid component and the diol component, out of 100 mol% of the total components. The intrinsic viscosity of the polymer that forms the hard segments is preferably in the range of 0.2 to 2.0, more preferably 0.5 to 1.5.

[0020] The soft segment, which consists of polyester units with aromatic dicarboxylic acids and / or aliphatic dicarboxylic acids 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 polymer formed from the segment has a melting point of 100°C or less, or 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 in the range of 0.5 to 1.5. The soft segment used is a soft segment consisting of polyester units with aromatic dicarboxylic acids and / or aliphatic carboxylic acids 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] For soft segment SS-1, it is preferable that the content of aromatic dicarboxylic acids is 60-99 mol% and the content of aliphatic dicarboxylic acids is 1-40 mol% of the total 100 mol% of dicarboxylic acid components, in order to obtain better transparency. It is more preferable that the content of aromatic dicarboxylic acids is 70-95 mol% and the content of aliphatic dicarboxylic acids is 5-30 mol%. It is even more preferable that the content of aromatic dicarboxylic acids is 85-93 mol% and the content of aliphatic dicarboxylic acids is 7-15 mol%. It is particularly preferable that the content of aromatic dicarboxylic acids is 89-92 mol% and the content of aliphatic dicarboxylic acids is 8-11 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 in terms of reducing crystallinity.

[0023] Suitable aliphatic dicarboxylic acids for SS-1 include linear aliphatic dicarboxylic acids having 4 to 12 carbon atoms, such as succinic acid, adipic acid, and sebacic acid, with sebacic acid being particularly preferred. As the C5-C15 diol component of SS-1, linear aliphatic diols with C6-C12 such as hexamethylene glycol, decamethylene glycol, 3-methylpentanediol, and 2-methyloctamethylenediol are more preferred, with hexamethylene glycol being particularly preferred.

[0024] SS-1 is particularly preferred because it has high compatibility with polycarbonate resin, allows for the acquisition of highly transparent materials, and also exhibits good surface properties and transparency after thermoforming. More specifically, SS-1 is preferably a polyester composed of isophthalic acid, sebaciate, and hexamethylene glycol.

[0025] In the present invention, the ratio of hard segments to soft segments in the polyester thermoplastic elastomer is preferably 20-70% by weight for hard segments and 80-30% by weight for soft segments, and more preferably 20-40% by weight for hard segments and 80-60% by weight for soft segments, based on 100% by weight of elastomer. The intrinsic viscosity of the polyester thermoplastic elastomer (value measured in o-chlorophenol at 35°C) is preferably 0.6 or higher, more preferably in the range of 0.8-1.5, and even more preferably in the range of 0.8-1.2. If the intrinsic viscosity is lower than the above range, the sheet strength may decrease, which is undesirable.

[0026] In the present invention, it is preferable that the A layer contains 1 to 20 parts by weight of polyester thermoplastic elastomer per 100 parts by weight of polycarbonate resin. If the amount of polyester thermoplastic elastomer is less than 1 part by weight, the glass transition temperature of the A layer may exceed 145°C, and if it exceeds 20 parts by weight, the glass transition temperature of the A layer may fall below 100°C.

[0027] 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, even more 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.

[0028] The A layer of the present invention may contain various additives commonly used in each resin. Examples include heat stabilizers, antioxidants, ultraviolet absorbers, antistatic agents, dyes, etc. Furthermore, reinforcing fillers such as glass fibers may be included, to the extent that they do not impair the effects of the present invention.

[0029] (Layer containing acrylic resin (Layer B)) In the present invention, the acrylic resin used in layer B is preferably mainly composed of a methacrylate ester or an acrylic ester polymer. If a resin other than an acrylic resin is used for layer B, for example, polycarbonate resin results in low surface hardness of the laminated film, making the molded article prone to scratches, which is undesirable. Also, PET resin is undesirable because it is prone to appearance defects due to uneven thickness. The acrylic resin is preferably a copolymer containing methyl methacrylate in an amount of 50 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, and particularly preferably 90 mol% or more.

[0030] Other copolymer components include ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate. Other copolymer components include other ethylenically unsaturated monomers. Specifically, these 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 maleimide. These may be used individually or in combination of two or more. The copolymer content is preferably 0 to 50% by weight, more preferably 0 to 30% by weight, and even more preferably 0 to 20% by weight. Acrylic resins are generally classified into emulsion polymerization, suspension polymerization, and continuous polymerization, but the acrylic resin used in the present invention may be produced by any of these polymerization methods. Furthermore, various additives such as general heat stabilizers, colorants, mold release agents, lubricants, antistatic agents, and matting agents may be added to layer B.

[0031] While rubber particles may be added to layer B of the present invention, it is preferable that it is substantially free of rubber particles. Although the addition of rubber particles to acrylic resin to improve toughness is a known and widely used technique, it is preferable to omit them from the viewpoint of ensuring transparency and surface hardness. 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, even more 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.

[0032] (Layer formed from the uncured material of the acrylate-based active energy ray-curable resin composition (Composition C) (Layer C)) The uncured material of the active energy ray curable resin composition (Composition C) constituting the C layer of the present invention contains an acrylate-based resin such as acrylate or urethane acrylate. The content is preferably in the range of 70 to 95% by mass of the total solid content of the C layer. If it is less than 70% by mass, the cohesive strength, chemical resistance, scratch resistance, optical properties, etc., of the coating film may decrease. If it exceeds 95% by mass, the start of photopolymerization will be delayed, which may result in poor productivity.

[0033] The acrylate resin contained in the C layer in the present invention may be either an oligomer or a prepolymer, and is not particularly limited. 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 after heat drying in the uncured state may have tackiness, and blocking may easily occur during roll winding. If the glass transition temperature is above 150°C, sufficient heat may not be applied during molding, which may cause cracking.

[0034] Furthermore, it is preferable that the pencil hardness of the cured layer after curing the uncured acrylate resin composition (composition C) by irradiating it with active energy rays such as ultraviolet light is H or higher. Achieving a pencil hardness within this range has the advantage of improving abrasion resistance. A pencil hardness of H or higher provides sufficient scratch resistance. Here, pencil hardness refers to the hardness of a sheet coated and dried with an acrylate-based resin composition (composition C), as described later in the examples, when the cumulative light intensity is 1000 mJ / cm².2 This refers to the value obtained by curing the coating film by irradiating it with ultraviolet light, preparing a test piece, and measuring the pencil hardness of the coating film in accordance with JIS K5600-5-4-1999.

[0035] In the present invention, the C layer can contain a photopolymerization initiator. By including a photopolymerization initiator, the polymerization curing reaction of the hard coat layer by light (ultraviolet) irradiation can be performed in a short time. Examples of photopolymerization initiators include benzophenone, benzyl, Michlar's ketone, 2-chlorothioxanthone, 2,4-diethylthioxanthone, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-diethoxyacetophenone, benzyldimethyl ketal, 2,2-dimethoxy-1,2-diphenylethane-1-one, 2-hydroxy-2-methyl-1-phenylpropane-1-one, 1-hydroxycyclohexylphenyl ketone, and 2-methyl-1-[4-(methylthio) Examples include phenyl]-2-morpholinopropanone-1, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, bis(cyclopentadienyl)-bis(2,6-difluoro-3-(pyru-1-yl)titanium, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1, and 2,4,6-trimethylbenzoyldiphenylphosphine oxide. These compounds may be used individually or in combination.

[0036] The amount of photopolymerization initiator contained in the solid content of layer C is preferably 0.01 to 10% by mass, and more preferably 0.1 to 5% by mass, of the total solid content of layer C. If the photopolymerization initiator content is less than 0.01% by mass, the photocurability may decrease, and if it is added at a concentration exceeding 10% by mass, discoloration of layer C may occur, which may be economically disadvantageous as the progress of the photocuring reaction does not change. In addition, it is possible to add various known dyes and sensitizers to improve the photocurability.

[0037] 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, even more preferably in the range of 2.5 to 20 μm, and particularly preferably in the range of 3 to 10 μm. Depending on the situation, the C layer may contain surfactants such as leveling agents, defoamers, and antifouling agents, additives such as surface modifiers, and fillers such as organic fillers and inorganic fillers.

[0038] (Hindered amine compounds) The C layer 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 exhibiting 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 inhibition of the C layer may occur.

[0039] (Protective film) In the thermoforming sheet of the present invention, it is preferable to laminate a protective film onto the surface of the C layer to protect the uncrosslinked C layer before curing from contamination and damage. The protective film is not particularly limited, but polyethylene film, polypropylene film, polyethylene terephthalate film, etc., can be preferably used. Considering the heat exposure in the process of forming a decorative layer on the side of the A layer of the thermoforming sheet of the present invention opposite to the B layer and C layer side by printing, etc., after lamination of the protective film, heat-resistant polypropylene film and polyethylene terephthalate film are more preferable.

[0040] (Method for manufacturing thermoformable sheets) The laminated sheet consisting of layers A and B that constitute the thermoforming sheet of the present invention can be manufactured by co-extrusion of molding material A for layer A and molding material B for layer B. Co-extrusion is a method for 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. By adjusting the extrusion amount, film formation speed, die slip interval, etc. of each extruder, it is possible to control the total thickness and thickness composition of the resulting laminated sheet.

[0041] Laminated sheets are formed by pressing molten resin tightly against rolls or belts. Furthermore, by compressing the molten resin with metal rolls before it cools and hardens, a metal mirror surface can be transferred, thereby improving the surface appearance of the laminated sheet. Examples of metal elastic rolls include those comprising an axial roll and a cylindrical metal thin film positioned to cover the outer surface of the axial roll and in contact with the molten resin, with a temperature-controlled fluid such as water or oil sealed between the axial roll and the metal thin film, or those with a metal belt wrapped around the surface of a rubber roll. In particular, metal elastic rolls with metal belts wrapped around two or more rolls can compress the molten resin over a wider arc-shaped surface, allowing for cooling while minimizing stress remaining within the resin.

[0042] To laminate the C layer, which constitutes the thermoforming sheet of the present invention, onto the laminated sheet of the A and B layers, a coating method is generally used. The coating method is not particularly limited, but coating can be performed using a method that allows for easy adjustment of the coating thickness, such as gravure coating, microgravure coating, fountain bar coating, slide die coating, or slot die coating. In the coating process, an acrylate-based active energy ray curable resin composition (composition C) and, if necessary, a hindered amine compound, initiator, and other additives are dissolved and dispersed in a suitable solvent, and the resulting coating is applied to the laminated sheet and dried to form the C layer. The solvent can be appropriately selected according to the solubility of composition C, and should be a solvent 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, and amides. Furthermore, the solvents may be used individually or in mixtures.

[0043] The thickness of the thermoforming sheet of the present invention is not particularly limited, but is preferably 0.05 mm or more and 3 mm or less, more preferably 0.1 mm or more and 2.5 mm or less, even more preferably 0.15 mm or more and 2 mm or less, and particularly preferably 0.2 mm or more and 1 mm or less.

[0044] (Method of manufacturing decorative sheets) The thermoforming sheet of the present invention may have a decorative layer, such as a printed layer, on the side of layer A opposite to layer B. Methods for forming the decorative layer include forming a pattern layer by printing, forming a thin film layer of metal or metal oxide, and these may be used in combination. As printing methods for forming the pattern layer, known printing methods such as gravure printing, planar printing, flexographic printing, dry offset printing, pad printing, and screen printing can be used 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 photoCVD. Thermal spraying methods include atmospheric pressure plasma spraying and reduced pressure plasma spraying. Plating methods include electroless plating, hot-dip plating, and electroplating. Furthermore, in thermoforming sheets and decorative sheets, it is preferable to make the C layer the outermost layer because it offers superior properties such as hardness.

[0045] (Method of manufacturing a molded product) Molded articles can be created using the thermoforming sheet or decorative sheet of the present invention. Examples of molded articles include automotive interior materials, automotive indicator panels, electrical appliances, cosmetic cases, building interior and exterior parts, cases for various equipment, products and miscellaneous goods, 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.

[0046] The molded body can be obtained by using a thermoforming sheet or a decorative sheet and performing various conventionally known molding processes. One method for molding a molded product is the insert molding method, which is an in-mold decoration method in injection molding. In this method, a thermoformable sheet or decorative sheet, which has been pre-shaped by vacuum forming or pressure forming to conform to the shape of the injection molding die cavity, is set inside the mold. Molten resin is then injected into the sheet, and at the same time as injection molding, the thermoformable sheet or decorative sheet is welded to the resin molded product and integrated to obtain a molded product.

[0047] As another method for forming other molded articles, a heat - forming sheet or a decorative sheet is attached to the mold cavity side by vacuum pressure, and molten resin is then injected thereinto. By applying heat and pressure, the heat - forming sheet or the decorative sheet is bonded to the resin molded article to obtain a molded article. Furthermore, methods of laminating by vacuum forming or pressure - air forming can be mentioned. As a heating method for the decorative film during heat forming, various methods such as an infrared heater, an electric heater, high - frequency induction, a halogen lamp, a microwave, a high - temperature conductor (such as steam), and a laser can be used.

[0048] It is preferable that the C layer is located on the outermost surface of the molded article. The molded article is cooled or allowed to cool, and subsequently, the C layer is cured by irradiating with radiation (ultraviolet rays, visible light, infrared rays, or electron beams). These radiations may be polarized or non - polarized. Particularly, ultraviolet rays are preferable from the viewpoints of equipment cost, safety, running cost, etc. When curing is performed by ultraviolet irradiation, the addition of a photoinitiator is necessary. As an energy ray source for ultraviolet rays, for example, a high - pressure mercury lamp, a halogen lamp, a xenon lamp, a metal halide lamp, a nitrogen laser, an electron beam accelerator, a radioactive element, etc. are preferable. The irradiation amount of the energy ray source, as the integrated exposure amount at an ultraviolet wavelength of 365 nm, is preferably in the range of 100 - 5,000 mJ / cm 2 and more preferably 300 - 3,000 mJ / cm 2 If the irradiation amount is less than 100 mJ / cm 2 , curing may be insufficient and the hardness may decrease. Also, if it exceeds 5,000 mJ / cm 2 , the C layer may be colored and the transparency may decrease. The oxygen concentration during radiation irradiation is preferably 5% or less, more preferably 3% or less, and particularly preferably 2% or less. For an oxygen - free or low - concentration atmosphere, the gas contained other than oxygen is preferably an inert gas. Examples of the inert gas include nitrogen, helium, neon, argon, etc.

Examples

[0049] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. The physical property measurements performed in the examples and comparative examples were carried out by the following methods. (Glass transition temperature) Using a TA Instruments 2920 DSC, measurements were taken at a heating rate of 20°C / min, and the falling edge was determined. (Total thickness of thermoforming sheet) This value represents the central part of the sheet in the width direction, measured using an electronic microfilm thickness gauge manufactured by Anritsu Corporation. The sheet width direction refers to the direction perpendicular to the sheet flow direction during film formation. (Pencil hardness) The integrated light intensity from the C-layer side of the created thermoforming sheet was 1000 mJ / cm². 2 The coating was cured by UV irradiation to create a test specimen, and the pencil hardness of the coating was measured in accordance with JIS K5600-5-4-1999. (Moldability) Using a biaxial stretching test apparatus (manufactured by Toyo Seiki Co., Ltd.), the thermoforming sheet was preheated for 1 minute at a temperature of (glass transition temperature + 20)°C for layer A. After stretching to a ratio of 1.3 at the same temperature, the appearance of the sheet was evaluated using the following indicators. ○: No cracks or clouding observed. △: Weak cracks or slight clouding are present. ×: Cracks or cloudiness are present.

[0050] [Preparation Example 1] (Production of polyester-based thermoplastic elastomer) To 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 a dibutyltin diacetate catalyst, followed by polycondensation under reduced pressure to obtain an amorphous polyester (soft segment) with an intrinsic viscosity of 1.06 and no endothermic peaks due to crystal melting as measured by DSC. To 100 parts by weight of the above polyester, 32 parts by weight of polybutylene terephthalate pellets (hard segment) with an intrinsic viscosity of 0.98 were added, and the reaction was carried out at 240°C for 45 minutes, after which 0.03 parts by weight of phenylphosphonic acid was added to stop the reaction. The resulting polymer had a melting point of 190°C and an intrinsic viscosity of 0.93.

[0051] [Example 1] (Molding material A) Polycarbonate resin pellets (Teijin Limited's Panlite L1250WP (bisphenol A homopolycarbonate resin (PC-A), viscosity-average molecular weight 23,900)) and the thermoplastic elastomer obtained in the above [Preparation Example] were pre-dried, mixed in a V-type blender in a ratio of 1 part by weight of thermoplastic elastomer to 100 parts by weight of polycarbonate resin pellets, and then extruded into pellets using a twin-screw extruder at a cylinder temperature of 260°C to obtain molding material A for layer A. The glass transition temperature of molding material A was 145°C.

[0052] (Molding material B) For the B layer, we prepared an acrylic resin (Acrypet VH-001 manufactured by Mitsubishi Rayon Co., Ltd., an acrylic resin copolymerized with 95 mol% methyl methacrylate and 5 mol% methyl acrylate).

[0053] (Co-extrusion) Molding material A and molding material B were extruded from a 650 mm wide T-die using a feed block system with a single-screw extruder with a screw diameter of 40 mm, under the conditions of cylinder temperature of 260°C (molding material A) and 250°C (molding material B), screw rotation speed of 11 rpm (molding material A) and 109 rpm (molding material B). The molten resin was then compressed and cooled using a metal roll and a metal sleeve roll, and after edge trimming, it was wound at a winding speed of 10.3 m / min to create a 400 mm wide laminated sheet with a two-layer structure of A layer / B layer (A layer 440 μm, B layer 60 μm).

[0054] (Paint adjustment) As a coating to form layer C, 100 parts by weight of the urethane acrylate-based UV-curable resin "Forseed No. 371C (trade name)" (solid content 40%, manufactured by Chugoku Marine Paints Ltd.), 5 parts by weight of Irgacure 184 (photopolymerization initiator, manufactured by Ciba Specialty Chemicals Co., Ltd.), and 5 parts by weight of the hindered amine compound "TINUVIN 292 (trade name)" (manufactured by BASF Ltd.) were diluted with methyl isobutyl ketone until the solid content concentration of the UV-curable resin in the coating was 30%, and the mixture was thoroughly stirred to prepare the coating.

[0055] (Coating) The coating for forming layer C was applied to the B layer side of a laminated sheet of layers A and B using a bar coater (#8), and then dried with hot air in an 80°C drying oven for 1 minute to form layer C with a thickness of 5 μm. After that, a polypropylene protective film (manufactured by Oji F-Tex Co., Ltd.) was laminated onto layer C to create a thermoforming sheet with a thickness of 0.5 mm. The results of various evaluations are shown in Table 1.

[0056] [Example 2] A thermoforming sheet was prepared in the same manner as in Example 1, except that the polyester thermoplastic elastomer content, laminated sheet thickness, and hindered amine compound content were changed as shown in Table 1. The various evaluation results are shown in Table 1.

[0057] [Example 3] A thermoforming sheet was prepared in the same manner as in Example 1, except that the polyester thermoplastic elastomer content, laminated sheet thickness, and hindered amine compound content were changed as shown in Table 1. The various evaluation results are shown in Table 1.

[0058] [Example 4] A thermoforming sheet was prepared in the same manner as in Example 1, except that the polyester thermoplastic elastomer content, laminated sheet thickness, and hindered amine compound content were changed as shown in Table 1. The various evaluation results are shown in Table 1.

[0059] [Example 5] A thermoforming sheet was prepared in the same manner as in Example 1, except that the content of the polyester-based 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.

[0060] [Example 6] In molding material B, rubber particles obtained by emulsion polymerization were mixed at a rate of 5 parts by weight per 100 parts by weight of acrylic resin. These particles consisted of a rigid polymer obtained by monomer polymerization of 93.8% methyl methacrylate, 6% methyl acrylate, and 0.2% allyl methacrylate for the innermost layer, an elastic polymer obtained by monomer polymerization of 81% butyl acrylate, 17% styrene, and 2% allyl methacrylate for the intermediate layer, and a rigid polymer obtained by monomer polymerization of 94% methyl methacrylate and 6% methyl acrylate for the outermost layer. Furthermore, a thermoforming sheet was prepared in the same manner as in Example 1, except that the content of the polyester thermoplastic elastomer and the thickness of the laminated sheet were changed as shown in Table 1. The results of various evaluations are shown in Table 1.

[0061] [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.

[0062] [Example 8] A thermoforming sheet was prepared in the same manner as in Example 1, except that the polyester thermoplastic elastomer content, laminated sheet thickness, and hindered amine compound content were changed as shown in Table 1. The various evaluation results are shown in Table 1.

[0063] [Example 9] A thermoforming sheet was prepared in the same manner as in Example 1, except that the laminated sheet thickness and the hindered amine compound content were changed as shown in Table 1. The results of various evaluations are shown in Table 1.

[0064] [Example 10] A thermoforming sheet was prepared in the same manner as in Example 1, except that the polyester thermoplastic elastomer content, laminated sheet thickness, and hindered amine compound content were changed as shown in Table 1. The various evaluation results are shown in Table 1.

[0065] [Example 11] During the production of 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). Furthermore, a thermoforming sheet was prepared in the same manner as in Example 1, except that the polyester thermoplastic elastomer content, laminated sheet thickness, and hindered amine compound content were changed as shown in Table 1. The various evaluation results are shown in Table 1.

[0066] [Example 12] After forming the C layer, no protective film was laminated. Furthermore, a thermoforming sheet was prepared in the same manner as in Example 1, except that the polyester thermoplastic elastomer content, laminate sheet thickness, and hindered amine compound content were changed as shown in Table 1. The various evaluation results are shown in Table 1.

[0067] [Comparative Example 1] In this example, no polyester-based thermoplastic elastomer was added to molding material A. Furthermore, a thermoforming sheet was prepared in the same manner as in Example 1, except that the laminated sheet thickness was changed as shown in Table 1. The various evaluation results are shown in Table 2.

[0068] [Comparative Example 2] A thermoforming sheet was prepared in the same manner as in Example 1, except that the polyester thermoplastic elastomer content, laminated sheet thickness, and hindered amine compound content were changed as shown in Table 1. The various evaluation results are shown in Table 2.

[0069] [Comparative Example 3] As the resin composition for forming layer C, instead of the urethane acrylate-based UV-curable resin "Forseed No. 371C", an isopropanol solution Tosguard 510 (manufactured by Momentive Performance Materials Co., Ltd.) mainly composed of trifunctional and tetrafunctional alkoxysilanes was applied, and then hot-air dried in an 80°C drying oven for 1 minute. In addition, 5 parts by weight of rubber particles obtained by emulsion polymerization were mixed with 100 parts by weight of acrylic resin to molded material B. These rubber particles consisted of a hard polymer obtained by monomer polymerization with the innermost layer consisting of 93.8% methyl methacrylate, 6% methyl acrylate, and 0.2% allyl methacrylate, an elastic polymer obtained by monomer polymerization with the middle layer consisting of 81% butyl acrylate, 17% styrene, and 2% allyl methacrylate, and a hard polymer obtained by monomer polymerization with the outermost layer 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 laminated sheet thickness and the hindered amine compound content were changed as shown in Table 1. The various evaluation results are shown in Table 2.

[0070] [Table 1]

[0071] [Table 2] [Industrial applicability]

[0072] The thermoformable sheet and decorative sheet of the present invention have excellent moldability and hardness, and molded articles using the thermoformable sheet and decorative sheet are useful as automotive interior materials, automotive indicator panels, electrical appliances, cosmetic cases, building interior and exterior parts, cases for various equipment, products and miscellaneous goods, 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. A thermoforming sheet for use in a mold decoration process in injection molding, comprising at least three layers laminated in this order: a layer containing a polycarbonate resin (layer A), a layer containing an acrylic resin (layer B), and a layer formed from the uncured material of a urethane acrylate-based active energy ray curable resin composition (composition C) (layer C), further comprising a protective film that can be peeled off from layer C, wherein the glass transition temperature (Tg) of layer A is 100°C or higher and 145°C or lower.

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

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

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

5. The thermoforming sheet according to any one of claims 1 to 4, wherein the C layer contains 1 to 5 parts by weight of a hindered amine compound per 100 parts by weight of 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 pencil hardness of the surface of the hardened layer obtained by irradiating the C layer with active energy rays and hardening it is H or higher.

7. A thermoforming sheet according to any one of claims 1 to 6, wherein the thickness of layer A is in the range of 50 to 3000 μm, and the thickness of layer B is in the range of 10 to 300 μm.

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

9. A decorative sheet having a decorative layer formed on the side of the A layer of the thermoforming sheet according to any one of claims 1 to 8 that is opposite to the B and C layers.

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