JP7712062B2 - Thermoforming sheet, decorative sheet, and molded body using the same - Google Patents

Description

The present invention relates to thermoforming sheets and decorative sheets that are suitable for use in a method of integrating a sheet imparted with a design or function with a resin molded product by thermoforming in order to impart chemical resistance, scratch resistance, and design to the surface of the resin molded product, and to molded articles using these.

In recent years, the number of plastic molded parts used in automobiles has increased due to the diversification of automobile designs and the demand for lighter automobiles. These plastic molded parts are required to have designs such as wood grain or metallic tones, and functions such as chemical resistance and scratch resistance. As a method for imparting design and function, a method of integrating a sheet with a specific design or function, such as a decorative sheet, with a plastic molded product has been proposed. Specific examples include the following two methods: (1) A method in which a sheet is preformed into a specific shape by thermoforming (vacuum forming, compressed air forming, etc.), which is then set in an injection molding die, and molten resin is injected into the die to form an injection molded body and simultaneously integrate it with the preformed sheet; and (2) A method in which a sheet is thermoformed to cover a prefabricated plastic molded product (three-dimensional surface decorative molding). Both of these methods (1) and (2) require the thermoforming of a sheet, and the thermoforming sheet used has 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.

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 is unable to follow three-dimensional molding once it has hardened, and when molding is performed using the above methods (1) and (2), the hard coat layer cracks.

As a countermeasure to the above, Patent Document 2 discloses an example of a so-called two-stage curing in a laminated hard-coated film in which an ultraviolet-curable hard-coat layer is formed on a substrate film, in which the hard-coat layer is cured with a weak ultraviolet exposure before three-dimensional molding, and then post-exposed after three-dimensional molding, thereby achieving both moldability and surface hardness. There is a concern that such two-stage curing may cause variation in moldability depending on the state of the first stage of curing, and may significantly shorten the product lifespan.

The thermoforming sheets used in the methods (1) and (2) are primarily required to have the following characteristics. First, moldability is required. In other words, it is important that the sheet has sufficient extensibility to follow three-dimensional molding, and that it does not develop defects in appearance such as cracks even when it is stretched. In particular, when high-temperature preheating is performed during molding, even if the sheet has good extensibility before heating, the preheating causes the functional layer to heat harden, resulting in a significant deterioration in extensibility. Secondly, surface hardness (pencil hardness, scratch resistance) is required. When the thermoforming sheet is integrated with a resin molded product, the functional layer is placed on the outermost surface, and the surface function of the resin molded product is required. To achieve this, high surface hardness is required, but there is generally a trade-off between the hardness and extensibility of the hard coat layer, and achieving both properties has been a challenge in the past.

Patent No. 5176749 JP 2012-210755 A

The object of the present invention is to provide a thermoforming sheet or decorative sheet that combines moldability and hardness, and a molded article using these. 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 to which chemical resistance and abrasion resistance have been imparted with a resin molded article by thermoforming in order to impart these functions to the surface of the resin molded article, and a molded article using these.

It has been found that the above-mentioned problems can be solved by a thermoforming sheet formed by laminating at least three layers, in at least this order: a layer (A layer) containing a specific polycarbonate-based resin, a layer (B layer) containing an acrylic-based resin, and a layer (C layer) formed from an uncured product of an acrylate-based active energy ray-curable resin composition (composition C).

That is, the present invention provides the following configuration:

1. A thermoforming sheet comprising at least three layers laminated in this order: a layer (A layer) containing a polycarbonate-based resin; a layer (B layer) containing an acrylic-based resin; and a layer (C layer) formed from an uncured product of an acrylate-based active energy ray-curable resin composition (composition C), wherein the glass transition temperature (Tg) of the A layer is 100°C or higher and 145°C or lower.

2. The thermoforming sheet according to the preceding paragraph 1, wherein the layer A contains a polyester thermoplastic elastomer, and the polyester thermoplastic elastomer is composed of a hard segment made of a polybutylene terephthalate unit and a soft segment made of a polyester unit having an aromatic dicarboxylic acid and an aliphatic dicarboxylic acid as a dicarboxylic acid component and a diol having 5 to 15 carbon atoms as a diol component.

3. The thermoforming sheet according to the preceding paragraph 2, in which the layer A contains 1 to 20 parts by weight of the polyester thermoplastic elastomer according to the preceding paragraph 2 per 100 parts by weight of polycarbonate resin.

4. A thermoforming sheet according to any one of the preceding paragraphs 1 to 3, in which layer B does not substantially contain rubber particles.

5. The thermoforming sheet according to any one of items 1 to 4 above, wherein the C layer 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. A thermoforming sheet according to any one of items 1 to 5 above, in which the surface of the cured layer obtained by irradiating the C layer with active energy rays and curing the layer has a pencil hardness of H or more.

7. The thermoforming sheet according to any one of items 1 to 6 above, in which 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 one of paragraphs 1 to 7 above, in which 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 side of layer A opposite to the side of layers B and C of the thermoforming sheet described in any one of paragraphs 1 to 8 above.

10. A method for producing a molded product, comprising forming the thermoforming sheet described in any one of the preceding paragraphs 1 to 8 or the decorative sheet described in any one of the preceding paragraphs 9 into the shape of a mold cavity, placing the sheet in the mold, and forming a resin material and integrating the sheet into the molded product at the same time. Thereafter, the method comprises post-exposing the molded product to active energy rays.

11. A method for producing a molded product, comprising attaching the thermoforming sheet described in any one of the preceding paragraphs 1 to 8 or the decorative sheet described in any one of the preceding paragraphs 9 to the cavity side of a mold using vacuum pressure, forming a molded product by integrating the sheet with the resin material at the same time, and then performing post-exposure to active energy rays.

The thermoforming sheet and decorative sheet of the present invention are thermoforming sheets and decorative sheets that combine moldability and hardness, and are particularly suitable for use in a method of integrating a sheet to which chemical resistance and abrasion resistance have been imparted to the surface of a resin molded product by thermoforming, and resin molded products using these can be used for automobile interior materials, electrical appliances, cosmetic cases, interior and exterior building materials, etc., and the industrial effects they provide are exceptional.

The present invention is 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 bonds, and is usually obtained by reacting a dihydroxy component with a carbonate precursor by interfacial polymerization or melt polymerization.

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 used alone as homopolymers or as copolymers of two or more of them. In terms of physical properties and cost, bisphenol A is preferred. 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.

Specific examples of polycarbonates include homopolymers of bisphenol A, homopolymers of bisphenol C, copolymers of bisphenol A and bisphenol C, copolymers of bisphenol A and 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, and copolymers of bisphenol A and 9,9-bis{(4-hydroxy-3-methyl)phenyl}fluorene. Homopolymers of bisphenol A are the most preferred.

Carbonate precursors include carbonyl halides, carbonate esters, and haloformates, such as phosgene, diphenyl carbonate, and dihaloformates of dihydric phenols.

When the dihydric dihydroxy compound and the carbonate precursor are reacted by the interfacial polymerization method or the melt polymerization method to produce the 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 polyfunctional aromatic compound having three or more functionalities, 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.

The molecular weight of the polycarbonate resin is preferably in the range of 13,000 to 40,000, expressed as a viscosity average molecular weight. If the molecular weight is lower than 13,000, the sheet may become brittle and may easily crack or burr during thermoforming, and if it is higher than 40,000, the melt viscosity of the resin composition with a polyester-based thermoplastic elastomer may become 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. In the case of a mixture of two or more polycarbonate resins, the molecular weight of the entire mixture is represented. Here, the viscosity average molecular weight is calculated by measuring the specific viscosity (η _sp ) at 20°C of a solution in which 0.7 g of polycarbonate is dissolved in 100 mL of methylene chloride, 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, [η] is the intrinsic viscosity)

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

The method for adjusting the glass transition temperature of the A layer is not particularly limited, but in order to ensure the transparency of the thermoforming sheet, a method of blending a polyester thermoplastic elastomer with a polycarbonate resin is preferred. In addition, the polyester thermoplastic elastomer is preferably a multiblock copolymer composed of a hard segment made of a polybutylene terephthalate unit and a soft segment made of a polyester unit 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.

The hard segment consisting 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. 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 of both the dicarboxylic acid component and the diol component, each of which is 100 mol %. 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.

The soft segment consisting of polyester units having aromatic dicarboxylic acid and aliphatic dicarboxylic acid as dicarboxylic acid components and diol having 5 to 15 carbon atoms as diol components refers to a segment in which the melting point of the polymer formed from the segment is 100°C or less, 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 aromatic dicarboxylic acid and/or aliphatic carboxylic acid as dicarboxylic acid components and diol having 5 to 15 carbon atoms as diol components. (Hereinafter, it may be referred to as "SS-1"). SS-1 is preferable because it provides extremely good transparency.

In terms of obtaining better transparency, the soft segment SS-1 preferably contains 60 to 99 mol% aromatic dicarboxylic acid and 1 to 40 mol% 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%.

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 reduced crystallinity.

As the aliphatic dicarboxylic acid of SS-1, linear 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.

As the diol component of SS-1 having 5 to 15 carbon atoms, 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.

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

In the present invention, the ratio of hard segments to soft segments in the polyester thermoplastic elastomer is suitably 20 to 70% by weight of hard segments and 80 to 30% by weight of soft segments, and more preferably 20 to 40% by weight of hard segments and 80 to 60% by weight of soft segments, in 100% by weight of elastomer. The intrinsic viscosity of the polyester thermoplastic elastomer (measured in o-chlorophenol at 35°C) is preferably 0.6 or more, more preferably in the range of 0.8 to 1.5, and even more preferably in the range of 0.8 to 1.2. If the intrinsic viscosity is lower than the above range, the sheet strength may decrease, which is not preferable.

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 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.

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.

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

(Layer containing acrylic resin (Layer B))
In the present invention, the acrylic resin used for the B layer 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 as the B layer, for example, a polycarbonate resin is not preferred because the surface hardness of the laminated film is low and the molded body is easily scratched. In addition, a PET resin is not preferred because it is prone to cause poor appearance due to uneven thickness. As the acrylic resin, a copolymer containing methyl methacrylate is preferably 50 mol% or more, more preferably 70 mol% or more, even more preferably 80 mol% or more, and particularly preferably 90 mol% or more is preferred.

Other copolymerization components include ethyl methacrylate, butyl methacrylate, 2-ethylhexyl methacrylate, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, etc. Other copolymerization components include other ethylenically unsaturated monomers. Specific examples include vinyl aromatic compounds such as styrene, α-methylstyrene, and vinyltoluene, diene compounds such as 1,3-butadiene and isoprene, alkenyl cyan 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 components is preferably 0 to 50% by weight, more preferably 0 to 30% by weight, and even more preferably 0 to 20% by weight. Methods for producing acrylic resins 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. In addition, various additives such as general heat stabilizers, colorants, release agents, lubricants, antistatic agents, and matting agents may be added to layer B.

Rubber particles may be added to Layer B of the present invention, but it is preferable that it does not substantially contain rubber particles. Adding rubber particles to acrylic resin to improve toughness is a well-known and widely used technique, but it is preferable that it does not contain rubber particles 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.

(Layer (C layer) formed from uncured acrylate-based active energy ray-curable resin composition (composition C))
The uncured product 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 an acrylate or a urethane acrylate. The content is preferably in the range of 70 to 95% by mass in 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 is more than 95% by 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.

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 be tacky, and blocking may easily occur when wound up into a roll. If the glass transition point is more than 150°C, sufficient heat may not be applied during molding, and cracks may occur.

In addition, it is preferable that the pencil hardness of the cured layer after irradiating an uncured acrylate resin composition (composition C) with active energy rays such as ultraviolet rays and curing is H or more. 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 more, scratch resistance is sufficient.

Here, the pencil hardness refers to a value obtained by coating and drying an uncured sheet of an acrylate-based resin composition (composition C) with ultraviolet light at an integrated light quantity of 1000 mJ/ ^cm2 to cure the coating film to prepare a test piece, and measuring the pencil hardness of the coating film in accordance with JIS K5600-5-4-1999, as described later in the Examples.

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 irradiation with light (ultraviolet rays) 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-diphenylethane-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1-[4-(methylthio)furan], and the like. Examples of the compounds include 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.

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, based on the total solid content of layer C. If the content of photopolymerization initiator is less than 0.01% by mass, the photocurability may decrease, and if it is blended in at more than 10% by mass, coloring of layer C may occur, and since the progress of the photocuring reaction does not change, it may be economically disadvantageous. It is also possible to add various known dyes and sensitizers to improve the photocurability.

The thickness of layer C 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, additives such as leveling agents, defoamers, and antifouling agents, as well as additives such as surface modifiers, and fillers such as organic fillers and inorganic fillers can be added to layer C.

(Hindered amine compounds)
The C layer of the present invention preferably contains a hindered amine compound. By containing a hindered amine compound, it is possible to capture thermal radicals generated by heat exposure during thermoforming, and thermal radical polymerization can be suppressed. In addition, 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 material of the 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.

(Protective film)
In the thermoforming sheet of the present invention, it is preferable to laminate a protective film on the surface of the C layer in order to protect the uncrosslinked C layer before curing from contamination or damage.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, etc. on the opposite side of the B layer and C layer of the A layer of the present invention, heat-resistant polypropylene film and polyethylene terephthalate film are more preferable.

(Method for producing thermoforming sheet)
The laminated sheet of layer A and layer B constituting 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. The co-extrusion method is a method in which molding material A and molding material B are melt-extruded using separate extruders and laminated using a feed block or a multi-manifold die to obtain a multi-layered sheet, and the total thickness and thickness composition of the obtained laminated sheet can be controlled by adjusting the extrusion rate and film-forming speed of each extruder, the die slip interval, etc.

The laminated sheet is formed by pressing the molten resin against a roll or belt. Furthermore, the molten resin before it cools and solidifies can be compressed with a metal roll to transfer a metal mirror surface, improving the surface appearance of the laminated sheet. Examples of metal elastic rolls include a shaft roll and a cylindrical metal thin film that is arranged to cover the outer periphery of the shaft roll and comes into contact with the molten resin. Examples include a roll in which a temperature-controlled fluid such as water or oil is sealed between the shaft roll and the metal thin film, and a roll in which a metal belt is wrapped around the surface of a rubber roll. In particular, a metal elastic roll with a metal belt wrapped around two or more rolls can compress the molten resin over a wider surface on a circular arc, thereby cooling the resin in a state where as little stress remains as possible.

In order to laminate the C layer constituting the thermoforming sheet of the present invention on the laminated sheet of the A layer and the B layer, a coating method is generally used. There is no particular limitation on the coating method, but coating can be performed by a method that makes it easy to adjust the coating thickness, such as gravure coating, microgravure coating, fountain bar coating, slide die coating, and slot die coating. In the coating process, a coating material in which an acrylate-based active energy ray curable resin composition (composition C) and, if necessary, a hindered amine-based compound, an initiator, and other additives are dissolved and dispersed in an appropriate solvent is applied to the laminated sheet and dried to form the C layer. The solvent can be appropriately selected depending on the solubility of composition C, and it is sufficient that at least the solid contents (resin, polymerization initiator, and other additives) can be uniformly dissolved or dispersed in the solvent. 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.

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.

(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 opposite to the B layer of the A layer. The method of forming the decorative layer includes the formation of a pattern layer by printing, the formation of a thin film layer of metal or metal oxide, and the like, and these may be used in combination. As the printing method for forming the pattern layer, known printing methods such as gravure printing, lithographic printing, flexographic printing, dry offset printing, pad printing, and screen printing can be used according to the product shape and printing purpose. As the method of forming a thin film layer of metal or metal oxide, vapor deposition, thermal spraying, plating, and the like can be mentioned. Specific examples of the vapor deposition method include vacuum vapor deposition, sputtering, ion plating, thermal CVD, plasma CVD, and photo CVD. In addition, examples of the thermal spraying method include atmospheric pressure plasma spraying and reduced pressure plasma spraying. Examples of the plating method include electroless plating, hot-dip plating, and electroplating.

In addition, in thermoforming sheets and decorative sheets, it is preferable to make layer C the outermost layer, as it has excellent properties such as hardness.

(Method for producing molded body)
Molded articles can be produced using the thermoforming sheet or decorative sheet of the present invention, including automobile interior materials, automobile 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, housings and exterior parts for home appliances and AV devices such as personal computers, mobile phones, and mobile devices, and the like.

The molded product can be obtained by carrying out various conventional molding processes using a thermoforming sheet or a decorative sheet.

The molding method for the molded body is the in-mold decoration method during 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 mold cavity is set inside 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, known as the insert molding method.

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

Furthermore, lamination methods using vacuum forming or compressed air forming can be used. Various methods can be used to heat the decorative forming film during thermoforming, including infrared heaters, electric heaters, high-frequency induction, halogen lamps, microwaves, high-temperature derivatives (steam, etc.), and lasers.

It is preferable that the C layer of the molded article is located on the outermost surface of the molded article. The molded article is cooled or allowed to cool, and then the C layer is cured by irradiating it with radiation (ultraviolet rays, visible light, infrared rays, or electron beams). These radiations may be polarized or unpolarized. In particular, ultraviolet rays are preferable from the viewpoints of equipment costs, safety, running costs, and the like. When curing is performed by irradiating ultraviolet rays, it is necessary to add a photopolymerization initiator. As the energy ray source of 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, and the like are preferable. The irradiation amount of the energy ray source is preferably in the range of 100 to 5,000 mJ/cm ² , more preferably 300 to 3,000 mJ/cm ² , as the cumulative exposure amount at an ultraviolet wavelength of 365 nm. If the irradiation amount is less than 100 mJ/cm ² , the curing may be insufficient and the hardness may decrease. If it exceeds 5,000 mJ/cm ² , the C layer may be colored and the 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 the inert gas include nitrogen, helium, neon, and argon.

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 property measurements in the examples and comparative examples were carried out by the following methods.
(Glass Transition Temperature)
The measurement was performed using a 2920 model DSC manufactured by TA Instruments at a temperature rise rate of 20° C./min, and the drop point was determined.
(Total thickness of thermoforming sheet)
The value is the value at the center in the sheet width direction measured with an electronic micro film thickness meter manufactured by Anritsu Corp. The sheet width direction refers to the direction perpendicular to the sheet flow direction during film formation.
(Pencil hardness)
The prepared thermoforming sheet was irradiated with ultraviolet light from the C layer side at an integrated light quantity of 1000 mJ/ ^cm2 to cure the coating film to prepare a test piece, and the pencil hardness of the coating film was measured in accordance with JIS K5600-5-4-1999.
(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 are observed △: Weak cracks or slight cloudiness are observed ×: Cracks or cloudiness are observed

[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 with dibutyltin diacetate catalyst, and then polycondensed under reduced pressure to obtain an amorphous polyester (soft segment) with an intrinsic viscosity of 1.06 and no endothermic peak due to melting of crystals when measured by DSC method. 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 further reacted at 240°C for 45 minutes, after which 0.03 parts by weight of phenylphosphonic acid was added to stop the reaction. The melting point of the obtained polymer was 190°C, and the intrinsic viscosity was 0.93.

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

(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.

(Co-extrusion)
Molding materials A and B were each extruded from a 650 mm wide T-die using a feed block method under conditions of 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 taken up at a take-up speed of 10.3 m/min to produce a 400 mm wide laminated sheet having a two-layer structure (layer A 440 μm, layer B 60 μm).

(Paint adjustment)
The paint for forming layer C was prepared by diluting 100 parts by weight of a urethane acrylate ultraviolet curing resin "Folseed No. 371C (product name)" (solid content 40%, manufactured by Chugoku Paint Co., Ltd.), 5 parts by weight of Irgacure 184 (photopolymerization initiator, manufactured by Chiba Specialty Chemical Co., Ltd.), and 5 parts by weight of a hindered amine compound "TINUVIN 292 (product name)" (manufactured by BASF Corporation) with methyl isobutyl ketone until the solid content concentration of the ultraviolet curing resin in the paint became 30%, and thoroughly stirring the mixture.

(Coating)
The paint for forming the C layer was applied to the B layer side of the laminated sheet of the A layer and the B layer using a bar coater (#8), and dried with hot air 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 onto the C layer to prepare a thermoforming sheet with a thickness of 0.5 mm. The various evaluation results are shown in Table 1.

[Example 2]
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 the various evaluations are shown in Table 1.

[Example 3]
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.

[Example 4]
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.

[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.

[Example 6]
The rubber particles were mixed with 100 parts by weight of acrylic resin using an emulsion polymerization method, in which 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 elastic 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, in an amount of 5 parts by weight per 100 parts by weight of acrylic resin. In addition, 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. Various evaluation results are shown in Table 1.

[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.

[Example 8]
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.

[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.

[Example 10]
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.

[Example 11]
When producing the polycarbonate resin pellets of 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 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.

[Example 12]
After the formation of the C layer, 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 the various evaluations are shown in Table 1.

[Comparative Example 1]
No polyester-based thermoplastic elastomer was added to molding material A. In addition, 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.

[Comparative Example 2]
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 the various evaluations are shown in Table 2.

[Comparative Example 3]
As a resin composition for forming the C layer, instead of the urethane acrylate-based ultraviolet curing resin "Folseed No. 371C", an isopropanol solution of Tosguard 510 (manufactured by Momentive Performance Materials Co., Ltd.) mainly composed of trifunctional and tetrafunctional alkoxysilanes was applied, and then hot air dried for 1 minute in a drying oven at 80 ° C. In addition, as rubber particles in the molding material B, 5 parts by weight of rubber particles obtained by emulsion polymerization method, in which the innermost layer is 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 is an elastic polymer obtained by polymerization of monomers consisting of 81% butyl acrylate, 17% styrene, and 2% allyl methacrylate, and the outermost layer is a hard polymer obtained by polymerization of monomers consisting of 94% methyl methacrylate and 6% methyl acrylate, were mixed with 100 parts by weight of acrylic resin. Further, a thermoforming sheet was prepared in the same manner as in Example 1, except that the thickness of the laminate sheet and the content of the hindered amine compound were changed as shown in Table 1. The results of the various evaluations are shown in Table 2.

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 automobile interior materials, automobile 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 devices such as personal computers, mobile phones, and mobile devices.

Claims (4)

A method for producing a molded body, comprising the steps of: laminating at least three layers, namely, a layer (A layer) containing a polycarbonate-based resin, a layer (B layer) containing an acrylic-based resin, and a layer (C layer) formed from an uncured product of a urethane acrylate-based active energy ray-curable resin composition (composition C), in this order; and forming a thermoforming sheet in which the glass transition temperature (Tg) of layer A is 100°C or higher and 145°C or lower, into the shape of a mold cavity in advance, placing the sheet in the mold, and producing a molded body that is integrated with the resin material at the same time as molding the resin material, and then performing post-exposure to active energy rays. A method for producing a molded product, comprising laminating at least four layers in this order: a decorative layer, a layer (A layer) containing a polycarbonate-based resin, a layer (B layer) containing an acrylic-based resin, and a layer (C layer) formed from an uncured product of a urethane acrylate-based active energy ray -curable resin composition (composition C), wherein the glass transition temperature (Tg) of layer A is 100°C or higher and 145°C or lower, the sheet being pre-shaped into the shape of a mold cavity and then placed in the mold, a molded product is produced by integrating the resin material with the sheet while the resin material is being molded, and then post-exposure to active energy rays is performed. A method for producing a molded body, comprising laminating at least three layers, 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 a urethane acrylate-based active energy ray-curable resin composition (composition C), wherein the glass transition temperature (Tg) of layer A is 100°C or higher and 145°C or lower, and attaching the thermoforming sheet to the cavity side of a mold under vacuum pressure to produce a molded body integrated with the resin material at the same time as molding, and then performing post-exposure to active energy rays. A method for producing a molded product, comprising laminating at least four layers in this order: a decorative layer, a layer (A layer) containing a polycarbonate-based resin, a layer (B layer) containing an acrylic-based resin, and a layer (C layer) formed from an uncured product of a urethane acrylate-based active energy ray -curable resin composition (composition C), wherein the glass transition temperature (Tg) of layer A is 100°C or higher and 145°C or lower, the sheet being attached to the cavity side of a mold by vacuum pressure, and a molded product is produced by integrating the resin material with the sheet at the same time as molding the resin material, and then performing post-exposure to active energy rays.