Thermoformable sheet

Abstract

To provide a thermoformed sheet which can reduce or prevent peeling and opening of breaks over time even when the thermoformed sheet is bonded to an adherend using a molding method involving heating.SOLUTION: There is provided a thermoformed sheet which contains a first adhesive layer, a second adhesive layer and a surface layer in this order, wherein the first adhesive layer contains 65 mass% or more of an acyclic aliphatic isocyanate polymer blocked by a blocking agent which starts to dissociate at a temperature less than 160°C in terms of solid content and has a thickness of 0.5 micrometers or more and 13 micrometers or less and the thermoformed sheet has a tensile strength of 3 N / 50 mm or more and 240 N / 50 mm or less when stretched to 200% at 95°C.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to thermoformed sheets.

Background Art

[0002] In recent years, a technique of laminating a thermoformed sheet having properties such as decorativeness to an adherend by using a forming method involving heating has been known.

[0003] Patent Document 1 (Japanese Patent Application Laid-Open No. 2012-111043) describes a multilayer film comprising a hard coat layer (A), a base film layer (B), a design layer (C) and an adhesive layer (D), wherein the adhesive layer (D) has at least one solid surface deactivating polyisocyanate (D1) having a melting point of 40°C or higher and a particle size of 200 μm or less, and at least one isocyanate-reactive polymer (D2), and is a multilayer decorative film used for vacuum forming.

[0004] Patent Document 2 (Japanese Patent Application Laid-Open No. 2018-512477) describes a decorative sheet for vacuum thermoforming, which includes an adhesive layer; a base material layer formed on top of the adhesive layer; a printing layer formed on top of the base material layer; and a transparent base material layer formed on top of the printing layer, wherein the adhesive layer is formed of an adhesive composition for vacuum thermoforming containing a polyurethane polymer and an acrylic polymer and having a difference between the melting temperature and the crosslinking temperature of 30°C to 60°C.

[0005] Patent Document 3 (Japanese Patent Application Laid-Open No. 2014-031003) describes a decorative molding film comprising at least two layers including an adhesive layer (A) and a layer (B) laminated on the adhesive layer (A), wherein the adhesive layer (A) comprises an olefin resin and an isocyanate group having an NCO content of 0.01 to 1.6 parts by mass, and the resin contained in the layer (B) has a hydroxy group, and is a decorative molding film to be heat-molded.

Prior Art Documents

Patent Documents

[0006] [Patent Document 1] Japanese Patent Publication No. 2012-111043 [Patent Document 2] Special Publication No. 2018-512477 [Patent Document 3] Japanese Patent Publication No. 2014-031003 [Overview of the project] [Problems that the invention aims to solve]

[0007] When a thermoformed sheet is bonded to an object using a heating-based molding method (for example, vacuum pressure forming), the sheet is applied to the object in a stretched state. As a result, tensile stress is applied to the stretched areas of the sheet, which could cause the sheet to peel off from the edges over time, or, if the stretched areas are damaged and cracked, the cracks could open up over time.

[0008] This disclosure provides a thermoformable sheet that can reduce or prevent peeling and tearing over time, even when the thermoformed sheet is bonded to an adherend using a heating molding method. [Means for solving the problem]

[0009] According to one embodiment of the present disclosure, a thermoformable sheet is provided, comprising a first adhesive layer, a second adhesive layer, and a surface layer in that order, wherein the first adhesive layer contains at least 65% by mass, by solid content, of an acyclic aliphatic isocyanate polymer blocked by a blocking agent that begins to dissociate at less than about 160°C, and has a thickness of at least 0.5 micrometers and at least 13 micrometers, and the thermoformable sheet has a tensile strength of at least 3 N / 50 mm and at least 240 N / 50 mm when stretched to 200% at 95°C.

[0010] According to another embodiment of the present disclosure, an article is provided in which the thermoformed sheet described above is bonded to a support member. [Effects of the Invention]

[0011] According to the present disclosure, even when a thermoformed sheet is bonded to an adherend using a forming method involving heating, it is possible to provide a thermoformed sheet that can reduce or prevent peeling over time and the opening of cuts.

[0012] The above description should not be regarded as disclosing all embodiments of the present invention and all advantages related to the present invention.

Brief Description of the Drawings

[0013] [Figure 1] It is a schematic cross-sectional view of a thermoformed sheet according to one embodiment. [Figure 2] It is a diagram exemplarily explaining a method of forming an article by applying a thermoformed sheet to a support member using a vacuum pressure air forming (DVT, Dual Vacuum Thermoforming) method. [Figure 3A] It is a schematic cross-sectional view of a vacuum pressure air forming machine before stretching in the DVT formability evaluation of an example. [Figure 3B] It is a top view showing the arrangement position of a support member (adherend) in the DVT formability evaluation of an example. [Figure 3C] It is a schematic cross-sectional view of a vacuum pressure air forming machine after stretching in the DVT formability evaluation of an example. [Figure 4] (a) is a photograph showing a grid-like cut made in a test piece in the heat shrinkage test of an example, and (b) is a photograph showing a grid-like cut made in a test piece in the heat shrinkage test of a comparative example.

Modes for Carrying Out the Invention

[0014] Hereinafter, for the purpose of exemplifying typical embodiments of the present invention, a more detailed description will be given with reference to the drawings as necessary, but the present invention is not limited to these embodiments. Regarding the reference numbers in the drawings, elements with similar numbers assigned in different drawings indicate similar or corresponding elements.

[0015] In the present disclosure, for example, in the "thermoformed sheet including a second adhesive layer and a surface layer in this order", the phrase "in this order" means that when focusing on the two components of the second adhesive layer and the surface layer, the thermoformed sheet contains these components in this order, and other layers such as a decorative layer may be interposed between these components.

[0016] In the present disclosure, for example, in the "the surface layer is disposed on the second adhesive layer", the "on" means that the surface layer is directly disposed on the upper side of the second adhesive layer, or the surface layer is indirectly disposed on the upper side of the second adhesive layer through another layer.

[0017] In the present disclosure, for example, in the "the decorative layer is disposed under the surface layer", the "under" means that the decorative layer is directly disposed on the lower side of the surface layer, or the decorative layer is indirectly disposed on the lower side of the surface layer through another layer.

[0018] In the present disclosure, "substantially" means including variations caused by manufacturing errors or the like, and it is intended that variations of about ±20% are allowed.

[0019] In the present disclosure, "transparent" means that the average transmittance in the visible light region (wavelength 400 nm to 700 nm) measured in accordance with JIS K 7375 is about 80% or more, desirably about 85% or more, or about 90% or more. There is no particular limitation on the upper limit value of the average transmittance, but for example, it can be less than about 100%, about 99% or less, or about 98% or less.

[0020] In the present disclosure, "translucent" means that the average transmittance in the visible light region (wavelength 400 nm to 700 nm) measured in accordance with JIS K 7375 is less than about 80%, desirably about 75% or less, and it is intended not to completely conceal the background or the like. [[ID=二十一]] [[ID=二十二]]

[0021] [[ID=二十三]] [[ID=二十四]]In the present disclosure, "(meth)acryl" means acrylic or methacrylic, and "(meth)acrylate" means acrylate or methacrylate. [[ID=二十五]]

[0022] In this disclosure, the term "sheet" also includes a component called "film."

[0023] The thermoformable sheet of this disclosure will be described below, with reference to the drawings as necessary.

[0024] In one embodiment, the thermoformed sheet comprises a first adhesive layer, a second adhesive layer, and a surface layer in that order, wherein the first adhesive layer contains at least 65% by mass, in terms of solid content, of an acyclic aliphatic isocyanate polymer blocked by a blocking agent that begins to dissociate at less than about 160°C, and has a thickness of at least 0.5 micrometers and at least 13 micrometers. The thermoformed sheet of this embodiment has a tensile strength of at least 3 N / 50 mm and at least 240 N / 50 mm when stretched to 200% at 95°C.

[0025] Figure 1 shows a schematic cross-sectional view of a thermoformable sheet 10 according to one embodiment. The thermoformable sheet 10 includes a first adhesive layer 16, a second adhesive layer 14, and a surface layer 12 on a release liner 20. Here, the release liner is an optional component, and the thermoformable sheet of this disclosure may or may not include a release liner.

[0026] Hereinafter, for the purpose of illustrating typical embodiments of this disclosure, details of each component will be described, with some reference numerals omitted.

[0027] The first adhesive layer of this disclosure contains at least 65% by solids of an acyclic aliphatic isocyanate polymer blocked with a blocking agent that begins to dissociate at less than about 160°C, and has a thickness of at least 0.5 micrometers and at least 13 micrometers. The first adhesive layer is typically applied to an adherend, for example, a support member of an article described later. The second adhesive layer of this disclosure differs from the first adhesive layer in that, for example, an adhesive layer used in conventional thermoformed sheets can be used. The inventors have found that simply incorporating the above-mentioned acyclic aliphatic isocyanate polymer into an adhesive layer used in conventional thermoformed sheets does not improve peeling or opening of the edges (sometimes simply referred to as "mouth opening") over time in the thermoformed sheet after application to an adherend, but that using the second adhesive layer in combination with the first adhesive layer can suitably improve peeling and mouth opening over time. Such peeling and opening are more likely to occur at high temperatures, but the thermoformed sheet of this disclosure can reduce or prevent peeling and opening even at high temperatures. Here, "high temperature" can be, for example, about 50°C or higher, about 70°C or higher, about 90°C or higher, or about 95°C or higher, about 120°C or lower, about 110°C or lower, or about 100°C or lower.

[0028] There are no particular restrictions on the blocking agent, as long as it is a blocking agent that begins to dissociate at a temperature of approximately 160°C or less. Thermoformed sheets are generally stored in warehouses or similar places before being bonded to an adherend. Therefore, from the viewpoint of storage properties that prevent the reaction of the acyclic aliphatic isocyanate polymer from progressing during storage, it is preferable that the lower limit of the dissociation initiation temperature of the blocking agent be approximately 50°C or higher, approximately 70°C or higher, approximately 90°C or higher, approximately 100°C or higher, or approximately 110°C or higher. On the other hand, during thermoforming, it is necessary to dissociate the blocking agent by heating during molding to allow the reaction of the acyclic aliphatic isocyanate polymer to proceed. Therefore, from the viewpoint of the reaction progress of the acyclic aliphatic isocyanate polymer during thermoforming, it is preferable that the upper limit of the dissociation initiation temperature of the blocking agent be approximately 150°C or lower, approximately 140°C or lower, less than approximately 140°C, approximately 130°C or lower, or approximately 120°C or lower. The blocking agent can be used alone or in combination of two or more types.

[0029] Examples of blocking agents include alcohols such as methanol, ethanol, isopropanol, n-butanol, heptanol, hexanol, 2-ethoxyhexanol, cyclohexanol, octanol, isononyl alcohol, stearyl alcohol, benzyl alcohol, 2-ethoxyethanol, methyl lactate, ethyl lactate, amyl lactate, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether), triethylene glycol monoethyl ether, N,N-dimethylaminoethanol, N,N-diethylaminoethanol, N,N-dibutylaminoethanol, phenol, ethylphenol, propylphenol, butylphenol, octylphenol, nonylphenol, nitrophenol, and chlorophenol. Phenols such as o-cresol, m-cresol, p-cresol, xylenol; lactams such as α-pyrrolidone, β-butyrolactam, β-propiolactam, γ-butyrolactam, δ-valerolactam; acetone oxime, methyl ethyl ketone oxime, methyl isobutyl ketone oxime, diethyl ketone oxime; oximes such as cyclohexanone oxime, acetophenone oxime, benzophenone oxime; pyrazole, 3,5-dimethylpyrazole, 3-methylpyrazole, 4-benzo Pyrazoles such as 3,5-dimethylpyrazole, 4-nitro-3,5-dimethylpyrazole, 4-bromo-3,5-dimethylpyrazole, and 3-methyl-5-phenylpyrazole; mercaptans such as butyl mercaptan, hexyl mercaptan, dodecyl mercaptan, and benzenethiol; active methylene compounds such as diethyl malonate, acetoacetate, dinitrile malonate, acetylacetone, methylenedisulfone, dibenzoylmethane, dipivaloylmethane, and acetone dicarboxylic acid diesters;Examples include amines such as dibutylamine, diisopropylamine, di-tert-butylamine, di(2-ethylhexyl)amine, dicyclohexylamine, benzylamine, diphenylamine, aniline, and carbazole; imidazoles such as imidazole and 2-ethylimidazole; imines such as methyleneimine, ethyleneimine, polyethyleneimine, and propyleneimine; acid amides such as acetanilide, (meth)acrylamide, acetic acid amide, and dimer acid amide; acid imides such as succinimide, maleimide, and phthalimide; and urea compounds such as urea, thiourea, and ethyleneurea. Among these, methyl ethyl ketone oxime, 3,5-dimethylpyrazole, and diethyl malonate are preferred, with 3,5-dimethylpyrazole being more preferred, from the viewpoint of storage properties and the reaction progress of acyclic aliphatic isocyanate polymers during thermoforming.

[0030] The acyclic aliphatic isocyanate polymers of the present disclosure are polymers of acyclic aliphatic isocyanate compounds. - or a modified acyclic aliphatic isocyanate compound, This is a polymer blocked with the blocking agent described above. Acyclic aliphatic isocyanate polymers can be used alone or in combination of two or more types.

[0031] Examples of acyclic aliphatic isocyanate compounds include 1,4-tetramethylene diisocyanate, 1,5-pentamethylene diisocyanate, 1,6-hexamethylene diisocyanate, 2,2,4-trimethyl-1,6-hexamethylene diisocyanate, and 1,3,6-hexamethylene triisocyanate. and Lysine diisocyanate Examples include: Modified acyclic aliphatic isocyanate compounds, These degenerations Body, example For example, isocyanurate, biuret, trimer, ethylene glycol adduct, propylene glycol adduct, trimethylolpropane adduct, ethanolamine adduct, allophanate, uretdione, polyester polyol adduct, polyether polyol adduct, polyamide adduct, polyamine adduct bodyThese can be listed. In particular, from the viewpoint of adhesive strength to the substrate (resistance to peeling) and resistance to opening, Acyclic aliphatic isocyanate polymers are 1,6-Hexamethylene diisocyanate (sometimes simply referred to as "hexamethylene diisocyanate" or "HDI"). polymer , and HDI At least one compound selected from the group consisting of modified compounds (e.g., biuret compound, trimer, trimethylolpropane adduct compound, allophanate compound, uretdione compound) is preferred. The acyclic aliphatic isocyanate compound can be used alone or in combination of two or more compounds.

[0032] The first adhesive layer of this disclosure contains at least 65% by mass, in terms of solid content, an acyclic aliphatic isocyanate polymer blocked with a blocking agent that begins to dissociate at less than about 160°C. From the viewpoint of adhesion to the adherend (anti-peeling properties) and resistance to opening, the amount of such polymer in the first adhesive layer is preferably at least 70% by mass, at least 75% by mass, at least 80% by mass, at least 85% by mass, at least 90% by mass, or at least 95% by mass, in terms of solid content. There is no particular upper limit to the amount of such polymer in the first adhesive layer, and it can be at least 100% by mass or less than 100% by mass.

[0033] The first adhesive layer of this disclosure has a thickness of approximately 0.5 micrometers or more and approximately 13 micrometers or less. When the thickness of the first adhesive layer is within this range, it is possible to obtain excellent adhesion to the adherend (anti-peeling properties) and resistance to opening, as well as reduce or prevent appearance defects such as air bubbles. In the case of a configuration in which only the first adhesive layer is used without a second adhesive layer, if the first adhesive layer has a thickness of approximately 13 micrometers or less, good adhesion to the adherend may not be obtained, or if the first adhesive layer has a thickness of more than approximately 13 micrometers, the rate of gas generation due to the dissociation of the blocking agent increases, which may result in appearance defects such as air bubbles due to the generated gas. The thermoformable sheet of this disclosure has an adhesive layer configuration with a specific first adhesive layer, which improves adhesion to the adherend (anti-peeling properties) and resistance to opening, while reducing or preventing appearance defects such as air bubbles.

[0034] The thickness of the first adhesive layer can be approximately 0.7 micrometers or more, approximately 1.0 micrometer or more, approximately 2.0 micrometers or more, approximately 3.0 micrometers or more, approximately 4.0 micrometers or more, or approximately 5.0 micrometers or more, and can be approximately 12 micrometers or less, approximately 11 micrometers or less, approximately 10 micrometers or less, approximately 9.0 micrometers or less, or approximately 8.0 micrometers or less.

[0035] Here, the thickness of the adhesive layer in this disclosure can be measured, for example, using the cross-sectional measurement method described in Japanese Patent Application Publication No. 2018-004789. Specifically, a sample piece is prepared by embedding a laminated thermoformed sheet in epoxy resin. This sample piece is sliced ​​to a thickness of 5 micrometers using a microtome. Then, the thickness of each layer contained in the thermoformed sheet can be measured by observing the cross-section revealed by the slicing using a microscope.

[0036] The first adhesive layer of this disclosure may contain, as optional components, fillers such as tackifying resins, crosslinking agents, conductive fillers, and thermally conductive fillers, silane coupling agents, plasticizers, thickeners, pigments, dyes, flame retardants, antioxidants, ultraviolet absorbers, stabilizers, etc. Such optional components can be used alone or in combination of two or more.

[0037] The first adhesive layer can be formed using a first adhesive composition comprising an acyclic aliphatic isocyanate polymer and a solvent, and optionally the above-mentioned optional components. Specifically, the first adhesive layer can be formed by applying the first adhesive composition onto the second adhesive layer and drying, solidifying, or curing it. Alternatively, the first adhesive layer can be formed by applying the first adhesive composition onto another release liner and drying, solidifying, or curing it, and then heat-laminating the first adhesive layer onto the second adhesive layer. For example, the first adhesive layer can be formed by applying the first adhesive composition to the second adhesive layer or release liner using a knife coat, bar coat, blade coat, doctor coat, roll coat, cast coat, etc., and then heating, drying, solidifying, or curing it as needed. The release liner may have a surface that has been released with silicone or the like.

[0038] The first adhesive layer generally forms a flat adhesive surface, but it may also form an uneven adhesive surface. This uneven adhesive surface includes an adhesive surface in which protrusions containing adhesive and recesses surrounding the protrusions are formed on the adhesive surface of the first adhesive layer, and when adhered to the adherend, a communication passage is formed between the adherend surface and the adhesive surface, which is defined by the recesses and communicates with the outside. An example of a method for forming an uneven adhesive surface is described below.

[0039] A release liner having a release surface with a predetermined uneven structure is prepared. A first adhesive composition is applied to the release surface of this release liner and heated as necessary to form a first adhesive layer. This transfers the uneven structure (negative structure) of the release liner to the surface of the first adhesive layer that is in contact with the release liner (this becomes the adhesive surface in the thermoformed sheet), forming an uneven adhesive surface with a predetermined structure (positive structure) on the adhesive surface. As described above, the unevenness of the adhesive surface is designed in advance to include grooves that can form communication passages when the protrusions are adhered to the adherend. Such unevenness may be formed only on the first adhesive layer, or it may be formed from the first adhesive layer to the second adhesive layer described later.

[0040] The grooves in the first adhesive layer may be arranged in a regular pattern on the adhesive surface by placing grooves of a certain shape along a regular pattern, as long as it prevents air bubbles from remaining when the thermoformed sheet is attached to the support member, which is the adherend, by a thermoforming method (e.g., DVT method), or irregular grooves may be arranged to form an irregular pattern. When multiple grooves are formed so as to be substantially parallel to each other, the spacing between the grooves is preferably about 10 to about 2,000 micrometers. The depth of the grooves is usually about 10 micrometers or more and about 100 micrometers or less. The depth of the grooves refers to the distance from the adhesive surface to the bottom of the groove measured in the thickness direction of the thermoformed sheet. The bottom of the grooves may be located anywhere on the thermoformed sheet, for example, within the first adhesive layer, beyond the first adhesive layer to the second adhesive layer, or beyond the first and second adhesive layers to another layer (e.g., decorative layer, surface layer) placed on the second adhesive layer. From the viewpoint of preventing air bubbles from remaining, the bottom of the groove is preferably located within the first adhesive layer or the second adhesive layer, and more preferably within the second adhesive layer. The shape of the groove is also not particularly limited as long as it does not impair the effects of the present invention. For example, the shape of the groove can be approximately rectangular (including trapezoidal), approximately semicircular, or approximately semielliptical in the cross-section of the groove in the direction perpendicular to the adhesive surface.

[0041] The thermoformable sheet of this disclosure includes a second adhesive layer. The second adhesive layer may be applied directly to the first adhesive layer and the surface layer, or indirectly via another layer (e.g., a decorative layer). The other layer may be applied to the entire surface of the second adhesive layer or to a portion of it. From the viewpoint of adhesion to the adherend (anti-peeling properties) and resistance to opening, it is preferable that the second adhesive layer is applied directly to the first adhesive layer.

[0042] There are no particular restrictions on the material of the second adhesive layer. For example, commonly used solvent-type, emulsion-type, pressure-sensitive, heat-sensitive, thermosetting, or UV-curing adhesives such as (meth)acrylic, polyolefin-based, polyurethane-based, polyester-based, and rubber-based adhesives can be used. Pressure-sensitive and heat-sensitive adhesives may also be crosslinked by thermal crosslinking with a crosslinking agent or by radiation (e.g., electron beam or ultraviolet light).

[0043] Among such materials, pressure-sensitive adhesives and heat-sensitive adhesives are preferred from the viewpoint of ease of bonding to the adherend, and heat-sensitive adhesives are more preferred from the viewpoint of being able to utilize heat such as an infrared heater during vacuum forming or vacuum pressure forming. In this disclosure, "pressure-sensitive adhesive" refers to an adhesive that is permanently tacky at room temperature (e.g., about 20°C), adheres to various surfaces with light pressure, and does not undergo a phase change (from liquid to solid). In this disclosure, "heat-sensitive adhesive" refers to a material that does not exhibit tackiness at room temperature but exhibits tackiness at high temperatures, and includes heat-activated adhesives and hot-melt adhesives. Heat-activated adhesives are also called delayed-tack heat-sensitive adhesives, and are activated by heating to produce tackiness, which persists for a while even after the heat source is removed. Hot-melt adhesives melt or soften by heating to produce tackiness, and rapidly solidify and lose tackiness when the heat source is removed. In general, heat-sensitive adhesives have a glass transition temperature (Tg) or melting point (Tm) higher than room temperature. When the temperature is higher than Tg or Tm, the storage modulus of the heat-sensitive adhesive decreases, causing the adhesive to exhibit tack. The Tg and Tm of the heat-sensitive adhesive are measured using differential scanning calorimetry (DSC).

[0044] There are no particular restrictions on the material of the pressure-sensitive adhesive; for example, (meth)acrylic polymers, natural rubber, synthetic rubber, polyester polymers, polyether polymers, polyurethane polymers, silicone polymers, or other polymers can be used. Among these, pressure-sensitive adhesives made of (meth)acrylic polymers are preferred because they have excellent transparency, weather resistance, and adhesion.

[0045] There are no particular restrictions on the material of the heat-sensitive adhesive, but (meth)acrylic heat-sensitive adhesives and polyurethane heat-sensitive adhesives are preferred from the viewpoint of adhesive strength (peel resistance) and resistance to opening of the bonded surface.

[0046] Examples of (meth)acrylic heat-sensitive adhesives include thermoplastic resins containing carboxyl group-containing (meth)acrylic polymers and amino group-containing (meth)acrylic polymers (hereinafter collectively referred to simply as "(meth)acrylic polymers") (hereinafter also referred to as "acrylic blend thermoplastic resins"). Such thermoplastic resins can be used alone or in combination of two or more types.

[0047] Acrylic blend thermoplastic resins include polymer blends of carboxyl group-containing (meth)acrylic polymers and amino group-containing (meth)acrylic polymers. The non-covalent interaction between the carboxyl group-containing (meth)acrylic polymers and the amino group-containing (meth)acrylic polymers imparts elongation properties and strength to the second adhesive layer. As a result, the thermoformed sheet has high stretchability suitable for methods such as DVT, allowing for stretching of more than 200% in area ratio when the area of ​​the thermoformed sheet before stretching is taken as 100%. Furthermore, even after being left in a high-temperature environment for a long time after stretching and bonding, the thermoformed sheet can maintain its adhesive state without breaking or peeling, and can also maintain its appearance, such as paint color. Carboxyl group-containing (meth)acrylic polymers can be obtained by copolymerizing a monoethylene unsaturated monomer with a carboxyl group-containing unsaturated monomer. Amino group-containing (meth)acrylic polymers can be obtained by copolymerizing a monoethylene unsaturated monomer with an amino group-containing unsaturated monomer.

[0048] Monoethylene unsaturated monomers are the main components of (meth)acrylic polymers, and are generally represented by the formula CH2=CR 1 COOR 2 (In the formula, R 1 R is a hydrogen or methyl group, 2 In addition to acrylates represented by the formula CH2=CR (where CH2 is a linear, branched, or cyclic alkyl group, phenyl group, alkoxyalkyl group, phenoxyalkyl group, hydroxyalkyl group, or cyclic ether group), the formula also includes aromatic vinyl monomers such as styrene, α-methylstyrene, and vinyltoluene, vinyl esters such as vinyl acetate, and unsaturated nitriles such as acrylonitrile and methacrylonitrile. 1 COOR 2Examples of monoethylene unsaturated monomers represented by include linear alkyl(meth)acrylates such as methyl(meth)acrylate, ethyl(meth)acrylate, n-butyl(meth)acrylate, n-hexyl(meth)acrylate, n-decyl(meth)acrylate, and n-dodecyl(meth)acrylate; branched alkyl(meth)acrylates such as isoamyl(meth)acrylate, 2-ethylhexyl(meth)acrylate, isooctyl(meth)acrylate, and isononyl(meth)acrylate; and alicyclic(meth)acrylates such as cyclohexyl(meth)acrylate and isobornyl(meth)acrylate. Examples include phenyl (meth)acrylate; alkoxyalkyl (meth)acrylates such as methoxypropyl (meth)acrylate and 2-methoxybutyl (meth)acrylate; phenoxyalkyl (meth)acrylates such as phenoxyethyl (meth)acrylate; hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; and cyclic ether-containing (meth)acrylates such as glycidyl (meth)acrylate and tetrahydrofurfuryl (meth)acrylate. As monoethylene unsaturated monomers, one or more monoethylene unsaturated monomers can be used, for example, to obtain a desired glass transition temperature, tensile strength, elongation properties, etc.

[0049] Examples of carboxyl group-containing unsaturated monomers include unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid; unsaturated dicarboxylic acids such as itaconic acid, fumaric acid, citraconic acid, and maleic acid; ω-carboxypolycaprolactone monoacrylate, monohydroxyethyl (meth)acrylate phthalate, β-carboxyethyl acrylate, 2-(meth)acryloyloxyethyl succinic acid, and 2-(meth)acryloyloxyethyl hexahydrophthalic acid. If necessary, one or more carboxyl group-containing unsaturated monomers can be used.

[0050] Carboxylic group-containing (meth)acrylic polymers can be obtained, for example, by copolymerizing monoethylene unsaturated monomers in amounts of approximately 85 parts by mass or more, approximately 90 parts by mass or more, or approximately 92 parts by mass or more, approximately 99.5 parts by mass or less, approximately 99 parts by mass or less, or approximately 98 parts by mass or less, with carboxylic group-containing monoethylene unsaturated monomers in amounts of approximately 0.5 parts by mass or more, approximately 1 part by mass or more, or approximately 2 parts by mass or more, approximately 15 parts by mass or less, approximately 10 parts by mass or less, or approximately 8 parts by mass or less.

[0051] Examples of amino group-containing unsaturated monomers include dialkylaminoalkyl (meth)acrylates such as N,N-dimethylaminoethyl acrylate (DMAEA) and N,N-dimethylaminoethyl methacrylate (DMAEMA); dialkylaminoalkyl (meth)acrylamides such as N,N-dimethylaminopropyl acrylamide (DMAPAA) and N,N-dimethylaminopropyl methacrylamide; dialkylaminoalkyl vinyl ethers such as N,N-dimethylaminoethyl vinyl ether and N,N-diethylaminoethyl vinyl ether; and monomers having tertiary amino groups, such as vinyl monomers having nitrogen-containing heterocycles, such as vinylimidazole. If necessary, one or more amino group-containing unsaturated monomers can be used as the amino group-containing unsaturated monomer.

[0052] Amino group-containing (meth)acrylic polymers can be obtained, for example, by copolymerizing monoethylene unsaturated monomers in proportions of about 80 parts by mass or more, about 85 parts by mass or more, or about 90 parts by mass or more, about 99.5 parts by mass or less, about 99 parts by mass or less, or about 97 parts by mass or less, with amino group-containing unsaturated monomers in proportions of about 0.5 parts by mass or more, about 1 part by mass or more, or about 3 parts by mass or more, about 20 parts by mass or less, about 15 parts by mass or less, or about 10 parts by mass or less.

[0053] Copolymerization is preferably carried out by radical polymerization, and known polymerization methods such as solution polymerization, suspension polymerization, emulsion polymerization, and bulk polymerization can be used. As initiators, for example, organic peroxides such as benzoyl peroxide, lauroyl peroxide, and bis(4-tert-butylcyclohexyl) peroxydicarbonate, and azo polymerization initiators such as 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), dimethyl-2,2'-azobis(2-methylpropionate), 4,4'-azobis(4-cyanovaleric acid), and 2,2'-azobis(2,4-dimethylvaleronitrile) (AVN) can be used. The amount of initiator used is generally about 0.01 parts by mass or more, or about 0.05 parts by mass or more, about 5 parts by mass or less, or about 3 parts by mass or less, per 100 parts by mass of the monomer mixture.

[0054] It is preferable that the glass transition temperature of one of the carboxyl group-containing (meth)acrylic polymer and the amino group-containing (meth)acrylic polymer is 0°C or higher, and the glass transition temperature of the other is 0°C or lower or less than 0°C. In other words, if the Tg of the carboxyl group-containing (meth)acrylic polymer is 0°C or higher, the Tg of the amino group-containing (meth)acrylic polymer is 0°C or lower or less than 0°C, and if the Tg of the former is 0°C or lower, the Tg of the latter is 0°C or higher or greater than 0°C. Although we do not wish to be bound by any theory, it is thought that (meth)acrylic polymers with high Tg impart high tensile strength to the second adhesive layer, and (meth)acrylic polymers with low Tg improve the elongation properties of the second adhesive layer. In some embodiments, the Tg of (meth)acrylic polymers having a high Tg is approximately 5°C or higher, approximately 20°C or higher, or approximately 40°C or higher, while the Tg of (meth)acrylic polymers having a low Tg is approximately -5°C or lower, approximately -20°C or lower, or approximately -40°C or lower.

[0055] For example, by copolymerizing homopolymers polymerized individually, such as methyl methacrylate (MMA) and n-butyl methacrylate (BMA), with (meth)acrylic monomers having a Tg of 0°C or higher as the main component, (meth)acrylic polymers with a Tg of 0°C or higher can be obtained.

[0056] For example, by copolymerizing a homopolymer of a single component, such as ethyl acrylate (EA), n-butyl acrylate (BA), or 2-ethylhexyl acrylate (2EHA), which has a Tg of 0°C or less, a (meth)acrylic polymer with a Tg of 0°C or less can be obtained.

[0057] The glass transition temperature (Tg) of carboxyl group-containing (meth)acrylic polymers and amino group-containing (meth)acrylic polymers is given by the following FOX formula (Fox, TG, Bull. Am. Phys. Soc., 1 (1956), p. 123), assuming that each polymer is copolymerized from n types of monomers.

number

number

[0058] When a carboxyl group-containing (meth)acrylic polymer or an amino group-containing (meth)acrylic polymer is a blend of two or more (meth)acrylic polymers with different weight-average molecular weights, the Tg of the blend can be determined by dynamic viscoelasticity measurement. Specifically, a solution of the (meth)acrylic polymer blend is applied to a release liner, and the resulting film (approximately 50 μm thick) is used as a test specimen. The loss tangent (tanδ) is measured using a dynamic viscoelasticity spectrometer (TA Instruments, model number: RSAIII) under the conditions of a temperature range of -20 to 160°C, Temp ramp mode, and frequency of 10 Hz. The Tg of the polymer blend can then be determined from this loss tangent measurement.

[0059] The weight-average molecular weight of the carboxyl group-containing (meth)acrylic polymer and the amino group-containing (meth)acrylic polymer is not particularly limited, but can be, for example, about 1,000 or more, about 5,000 or more, or about 10,000 or more, about 2,000,000 or less, about 1,500,000 or less, or about 1,000,000 or less. In this disclosure, the weight-average molecular weight refers to the value converted using standard polystyrene by the GPC method.

[0060] In one embodiment, the weight-average molecular weight of a (meth)acrylic polymer (low Tg (meth)acrylic polymer) having a glass transition temperature of 0°C or less or less than 0°C is approximately 100,000 or more, approximately 150,000 or more, or approximately 200,000 or more, approximately 2,000,000 or less, approximately 1,500,000 or less, or approximately 1,000,000 or less.

[0061] In one embodiment, the weight-average molecular weight of a (meth)acrylic polymer (high Tg (meth)acrylic polymer) having a glass transition temperature of 0°C or higher or greater than 0°C is approximately 1,000 or higher, approximately 5,000 or higher, or approximately 10,000 or higher, approximately 200,000 or lower, approximately 180,000 or lower, or approximately 150,000 or lower.

[0062] By changing the blending ratio of carboxyl group-containing (meth)acrylic polymer and amino group-containing (meth)acrylic polymer, desired tensile strength and elongation properties can be imparted to thermoformed sheets. In one embodiment, the blending ratio of high-Tg (meth)acrylic polymer and low-Tg (meth)acrylic polymer among the carboxyl group-containing (meth)acrylic polymer and amino group-containing (meth)acrylic polymer is such that, when the high-Tg (meth)acrylic polymer is 100 parts by mass, the low-Tg (meth)acrylic polymer is approximately 10 parts by mass or more, approximately 20 parts by mass or more, approximately 50 parts by mass or more, or approximately 80 parts by mass or more, approximately 900 parts by mass or less, approximately 500 parts by mass or less, approximately 200 parts by mass or less, or approximately 150 parts by mass or less.

[0063] The total content of carboxyl group-containing (meth)acrylic polymers and amino group-containing (meth)acrylic polymers in the acrylic blend thermoplastic resin is generally about 25% by mass or more, about 35% by mass or more, or about 45% by mass or more, 100% by mass or less, about 90% by mass or less, or about 80% by mass or less.

[0064] It is preferable to crosslink carboxyl group-containing (meth)acrylic polymers with each other, or with an amino group-containing (meth)acrylic polymer. These crosslinks form a network structure, further improving the strength and elongation properties of the thermoformed sheet. Examples of crosslinking agents for carboxyl group-containing (meth)acrylic polymers include epoxy crosslinking agents, bisamide crosslinking agents, aziridine crosslinking agents, and carbodiimide crosslinking agents. One or more crosslinking agents can be used as needed.

[0065] Examples of epoxy crosslinking agents include N,N,N',N'-tetraglycidyl-1,3-benzenedi(methaneamine) (product name TETRAD-X (Mitsubishi Gas Chemical Co., Ltd., Chiyoda-ku, Tokyo, Japan), E-AX, E-5XM (Soken Chemical Co., Ltd., Toshima-ku, Tokyo, Japan)); and N,N'-(cyclohexane-1,3-diylbismethylene)bis(diglycidylamine) (product name TETRAD-C (Mitsubishi Gas Chemical Co., Ltd., Chiyoda-ku, Tokyo, Japan), E-5C (Soken Chemical Co., Ltd., Toshima-ku, Tokyo, Japan)). Examples of bisamide crosslinking agents include 1,1'-(1,3-phenylenedicarbonyl)bis(2-methylaziridine), 1,4-bis(ethyleneiminocarbonylamino)benzene, 4,4'-bis(ethyleneiminocarbonylamino)diphenylmethane, and 1,8-bis(ethyleneiminocarbonylamino)octane. Examples of aziridine crosslinking agents include Chemitite PZ33 (Nippon Shokubai Co., Ltd., Osaka, Japan) and NeoCryl CX-100 (DSM Coating Resins, LLC., Zwolle, Overijssel, Netherlands). Examples of carbodiimide crosslinking agents include Carbodilite V-03, V-05, and V-07 (Nisshinbo Chemical Co., Ltd., Chuo-ku, Tokyo, Japan).

[0066] The amount of crosslinking agent added can be approximately 0.01 parts by mass or more, approximately 0.05 parts by mass or more, or approximately 0.1 parts by mass or more, approximately 5 parts by mass or less, approximately 3 parts by mass or less, or approximately 2 parts by mass or less, per 100 parts by mass of carboxyl group-containing (meth)acrylic polymer.

[0067] Polyurethane-based heat-sensitive adhesives contain polyurethane, which is a reaction product of a polyol and a polyisocyanate. Examples of polyols include high molecular weight polyols such as polyester polyols, polyether polyols, and polycarbonate polyols, and low molecular weight polyols with 2 to 20 carbon atoms such as ethylene glycol, 1,2-propanediol, 1,3-propanediol, 2-methyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, glycerin, diethylene glycol, trimethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, cyclohexanedimethanol, methylpentanediol adipate, trimethylolpropane, and pentaerythritol. Examples of polyisocyanates include aliphatic polyisocyanates such as 1,6-hexamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, and lysine diisocyanate; alicyclic polyisocyanates such as isophorone diisocyanate, trans and / or cis-1,4-cyclohexane diisocyanate, norbornene diisocyanate, and hydrogenated diphenylmethane diisocyanate; aromatic polyisocyanates such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, and 2,2'-diphenylmethane diisocyanate; and their biuret-modified, isocyanurate-modified, carbodiimide-modified, or adduct-modified forms. One or more polyols or polyisocyanates can be used as the polyol or polyisocyanate.

[0068] Polyurethane-based heat-sensitive adhesives preferably contain linear polyurethane. The polyurethane may have hydroxyl groups. Polyurethane having hydroxyl groups can be obtained by reacting a polyol and a polyisocyanate such that the NCO / OH ratio (number of moles of isocyanate groups in the polyisocyanate / number of moles of hydroxyl groups in the polyol) is less than 1, i.e., there is an excess of hydroxyl groups.

[0069] From the viewpoint of suppressing thermal shrinkage of thermoformed sheets, it is preferable that the polyurethane-based heat-sensitive adhesive is crosslinked. A crosslinked polyurethane-based heat-sensitive adhesive can be formed by reacting a polyurethane having hydroxyl groups with the above-mentioned polyisocyanate as a crosslinking agent. Excess isocyanate groups of the above-mentioned polyisocyanate also react with moisture contained in the air and elsewhere to contribute to crosslinking. The NCO / OH ratio (moles of isocyanate groups of the polyisocyanate / moles of hydroxyl groups of the polyurethane having hydroxyl groups) of the polyurethane having hydroxyl groups and the crosslinking agent polyisocyanate can be, for example, about 0.5 or more, about 1 or more, or about 2 or more, about 10 or less, about 8 or less, or about 6 or less.

[0070] The melting point (Tm) of the polyurethane-based heat-sensitive adhesive before crosslinking can be approximately 30°C or higher, approximately 35°C or higher, or approximately 40°C or higher, approximately 80°C or lower, approximately 65°C or lower, or approximately 50°C or lower. The melting point (Tm) of the polyurethane-based heat-sensitive adhesive is a value measured using a differential scanning calorimeter.

[0071] The second adhesive layer may further contain a tackifier. Examples of tackifiers include rosin derivatives, terpene resins, petroleum resins, phenolic resins, and xylene resins.

[0072] The heat-activated, heat-sensitive adhesive layer may further contain a solid plasticizer. The solid plasticizer is solid at room temperature and melts when heated above its melting point, causing swelling or dissolution of materials such as polyurethane or tackifiers. This enhances the tack of the heat-sensitive adhesive layer at high temperatures. On the other hand, once the solid plasticizer melts, crystallization proceeds slowly even when the temperature drops below its melting point, allowing the tack generated by heat activation to be maintained for a long period of time. Examples of solid plasticizers include diphenyl phthalate, dihexyl phthalate, dicyclohexyl phthalate, dihydroabiethyl phthalate, dimethyl isophthalate, sucrose benzoate, ethylene glycol dibenzoate, trimethylolethane tribenzoate, glyceride tribenzoate, sucrose octaacetate, tricyclohexyl citrate, and N-cyclohexyl-p-toluenesulfonamide.

[0073] The second adhesive layer may also contain, as an optional component, for example, UV absorbers such as benzotriazole, light stabilizers such as hindered amines, antioxidants such as phenolic antioxidants, silane coupling agents, crosslinking agents, fillers such as conductive fillers and thermally conductive fillers, plasticizers other than those mentioned above, thickeners, pigments, dyes, flame retardants, stabilizers, etc.

[0074] The thickness of the second adhesive layer may vary, but from the viewpoint of adhesive strength (anti-peeling properties) and resistance to opening, it is preferably about 10 micrometers or more, about 15 micrometers or more, about 20 micrometers or more, about 25 micrometers or more, about 30 micrometers or more, or about 35 micrometers or more, and preferably about 140 micrometers or less, about 130 micrometers or less, about 120 micrometers or less, about 110 micrometers or less, about 100 micrometers or less, or about 90 micrometers or less.

[0075] The second adhesive layer can be formed using a second adhesive composition containing, for example, a carboxyl group-containing (meth)acrylic polymer and an amino group-containing (meth)acrylic polymer, or polyurethane, and optionally a solvent and / or a crosslinking agent. Specifically, the second adhesive layer can be formed on the surface layer or release liner by applying the second adhesive composition to the surface layer or release liner such as a release-treated PET film, and then drying, solidifying, or curing it. Alternatively, the second adhesive layer can be formed by applying the second adhesive composition onto the first adhesive layer formed on the release liner, and then drying, solidifying, or curing it. As the coating device, a conventional coater, such as a bar coater, knife coater, roll coater, or die coater, can be used. Drying, solidification, or curing can be carried out by drying the second adhesive composition containing a volatile solvent, cooling the molten resin component, etc. The second adhesive layer can also be formed by melt extrusion.

[0076] The second adhesive layer generally has a flat adhesive surface, but may also have an uneven surface corresponding to the uneven adhesive surface of the first adhesive layer described above. Such an uneven surface of the second adhesive layer can be obtained, for example, by using a release liner having a release surface with a predetermined uneven structure, similar to the first adhesive layer. For example, a release liner having a release surface with an uneven structure greater than the thickness of the first adhesive layer is prepared, the first adhesive composition is applied to the release surface of this release liner, and heated as necessary to form the first adhesive layer. Next, the second adhesive composition is applied to the first adhesive layer, on which the uneven structure of the release liner remains, and heated as necessary to form the second adhesive layer. As a result, the uneven structure (negative structure) of the release liner is transferred to the surface of the second adhesive layer that is in contact with the first adhesive layer, and an uneven surface having a predetermined structure (positive structure) is formed on the second adhesive layer.

[0077] The thermoformed sheet of this disclosure includes a surface layer. The material of the surface layer is not particularly limited, and for example, (meth)acrylic resins including polymethyl methacrylate (PMMA) and (meth)acrylic copolymer, resins having urethane bonds (e.g., polyurethane), fluororesins such as ethylene-tetrafluoroethylene copolymer (ETFE), polyvinylidene fluoride (PVDF), methyl methacrylate-vinylidene fluoride copolymer (PMMA / PVDF), and tetrafluoroethylene-hexafluoropropylene-vinylidene fluoride copolymer (THV), silicone resins, polyolefins such as polyvinyl chloride (PVC), polycarbonate (PC), polyethylene (PE), and polypropylene (PP), polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyamides such as nylon, ethylene / acrylic acid copolymer (EAA) and its ionomer, copolymers such as ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer, and ethylene-vinyl alcohol copolymer (EVOH) can be used alone or in blends of two or more. The surface layer may have a multilayer structure. For example, the surface layer may be a laminate of films formed from the above resin, or it may be a multilayer coating of the above resin. The surface layer may have a three-dimensional uneven shape, such as an embossed pattern, on all or part of its surface. Herein, in this disclosure, "resin having urethane bonds" can include not only urethane resins, but also resins prepared using at least one selected from, for example, urethane (meth)acrylate and urethane (meth)acrylate oligomers, and urethane resins can also include (meth)acrylic urethane resins.

[0078] The surface layer can be formed by coating the second adhesive layer with a resin composition, either directly or via a bonding layer. The surface layer coating can be performed before or after applying the thermoformed sheet to the adherend (e.g., the support member described later). Alternatively, a surface layer film can be formed by coating the release liner with a resin composition, and then laminating this film to the second adhesive layer, either directly or via a bonding layer. The surface layer film can be formed by coating a release liner with a resin material such as a curable (meth)acrylic resin composition or a reactive polyurethane composition using a knife coat, bar coat, blade coat, doctor coat, roll coat, cast coat, etc., and then curing it with light or heat as needed.

[0079] As the surface layer, a film pre-formed by extrusion, stretching, etc., may be used. Such a film can be laminated to the second adhesive layer directly or via a bonding layer, etc. By using a film with high flatness as such, an appearance with higher surface flatness can be given to the article (structure). The surface layer can also be formed by multilayer extrusion with other layers. As other layers, for example, a (meth)acrylic film can be used. As the (meth)acrylic film, for example, a resin containing polymethyl methacrylate (PMMA), butyl polyacrylate, (meth)acrylic copolymer, ethylene / acrylic copolymer, ethylene vinyl acetate / acrylic copolymer, etc., can be used in film form. (Meth)acrylic films have excellent transparency and / or scratch resistance, are resistant to heat and / or light, and are less prone to fading and / or gloss changes. In addition, they have excellent moldability even without the use of plasticizers, and because plasticizers do not need to be used, they also have excellent stain resistance. Among these, those mainly composed of PMMA are preferred. For example, if a (meth)acrylic resin with excellent scratch resistance is used as another layer, and a fluororesin such as ETFE, PVDF, or PMMA / PVDF with excellent chemical resistance is used as the surface layer, the resulting surface layer may possess properties that combine those of both layers.

[0080] The surface layer of this disclosure may contain optional components, such as fillers, antioxidants, UV absorbers, light stabilizers, heat stabilizers, hard coat materials, gloss enhancers, dispersants, plasticizers, flow enhancers, surfactants, leveling agents, silane coupling agents, catalysts, pigments, and dyes, to the extent that they do not impair the performance (e.g., protective performance) according to the application. In particular, by using UV absorbers such as benzotriazole and Tinuvin® 400 (manufactured by BASF), and hindered amine light stabilizers (HALS) such as Tinuvin® 292 (manufactured by BASF), discoloration, fading, and deterioration of the underlying layer can be effectively prevented. The hard coat material may be included in the surface layer, or it may be applied as a hard coat layer by being separately coated on the surface layer.

[0081] The surface layer may be transparent, translucent, or opaque. If the thermoformed sheet includes a decorative layer, the surface layer may be partially translucent or opaque, but it is preferable that it be transparent from the viewpoint of the visibility of the decorative layer.

[0082] The thickness of the surface layer can vary, but for example, it may be about 1 micrometer or more, about 5 micrometers or more, about 10 micrometers or more, about 20 micrometers or more, or about 30 micrometers or more, and may be about 200 micrometers or less, less than about 200 micrometers, about 180 micrometers or less, about 150 micrometers or less, about 130 micrometers or less, about 100 micrometers or less, or about 80 micrometers or less. From the viewpoint of resistance to opening, the thickness of the surface layer is preferably less than about 200 micrometers or about 180 micrometers or less. When applying a thermoformed sheet to a support member with a complex shape, a thinner surface layer is advantageous from the viewpoint of shape conformability, and for example, it is preferably about 100 micrometers or less, or about 80 micrometers or less. On the other hand, when providing articles with high chemical resistance, weather resistance, scratch resistance, etc., a thicker surface layer is advantageous, and for example, it is preferably about 5 micrometers or more, about 10 micrometers or more, about 20 micrometers or more, or about 30 micrometers or more.

[0083] The thermoformable sheet of this disclosure may optionally include additional layers. Examples of such additional layers include at least one selected from the group consisting of decorative layers (e.g., color layers, pattern layers, relief layers), bonding layers, intermediate film layers, and release liners. The additional layers may be applied to the entire surface or to a portion of the thermoformable sheet. The additional layers may have a three-dimensional shape, such as an embossed pattern, on their surface.

[0084] The additional layer may contain, as optional components, fillers such as tackifying resins, crosslinking agents, conductive fillers, and thermally conductive fillers, silane coupling agents, plasticizers, thickeners, pigments, dyes, flame retardants, antioxidants, UV absorbers, stabilizers, dispersants, flow enhancers, surfactants, catalysts, etc. These optional components can be used individually or in combination of two or more.

[0085] Decorative layers include, but are not limited to, the following: color layers exhibiting paint colors, such as light colors like white and yellow, and dark colors like red, brown, green, blue, gray, and black; pattern layers that impart patterns such as wood grain, stone patterns, geometric patterns, and leather patterns to an object; relief layers with raised or recessed shapes on the surface; and combinations thereof.

[0086] The decorative layer can be applied directly or via a bonding layer to all or part of the layers constituting the thermoformed sheet, such as the surface layer, first adhesive layer, second adhesive layer, etc., although this is not limited to the following.

[0087] The material for the color layer is not limited to the following, but for example, materials can be used in which pigments such as inorganic pigments such as carbon black, lead yellow, yellow iron oxide, red iron oxide, etc., phthalocyanine pigments such as phthalocyanine blue, phthalocyanine green, etc., organic pigments such as azolake pigments, indigo pigments, perinone pigments, perylene pigments, quinophthalone pigments, dioxazine pigments, quinacridone pigments such as quinacridone red, etc. are dispersed in a binder resin such as a (meth)acrylic resin or a resin having urethane bonds. Among these, resins having urethane bonds are preferred from the viewpoint of impact resistance, etc.

[0088] The color layer can be formed using such materials by coating methods such as gravure coating, roll coating, die coating, bar coating, and knife coating.

[0089] The pattern layer is not limited to the following, but for example, patterns such as designs, logos, and illustrations may be directly applied to the surface layer, first adhesive layer, second adhesive layer, etc., using printing methods such as gravure direct printing, gravure offset printing, inkjet printing, laser printing, and screen printing. Alternatively, films, sheets, etc., having designs, logos, and illustrations formed by coatings such as gravure coating, roll coating, die coating, bar coating, and knife coating, as well as by die-cutting and etching, may be used. As for the material of the pattern layer, for example, the same material used for the color layer may be used.

[0090] As the relief layer, a thermoplastic resin film having an uneven surface shape achieved by conventionally known methods, such as embossing, scratching, laser processing, dry etching, or hot pressing, can be used. Alternatively, a thermosetting or radiation-curable resin, such as a curable (meth)acrylic resin, can be applied to a release liner having an uneven surface shape, cured by heating or radiation, and then the release liner can be removed to form the relief layer.

[0091] The thermoplastic resin, thermosetting resin, and radiation-curable resin used in the relief layer are not particularly limited, but for example, fluororesins, polyester resins such as PET and PEN, (meth)acrylic resins, polyolefin resins such as polyethylene and polypropylene, thermoplastic elastomers, polycarbonate, polyamide, ABS resin, acrylonitrile-styrene resin, polystyrene, vinyl chloride, and resins having urethane bonds can be used. Among these, resins having urethane bonds are preferred from the viewpoint of impact resistance, etc. The relief layer may also contain at least one of the pigments used in the color layer.

[0092] The thickness of the decorative layer is not particularly limited and can be adjusted as appropriate according to the required level of decoration, but for example, it can be about 1.0 micrometer or more, about 3.0 micrometers or more, or about 5.0 micrometers or more, and can be about 50 micrometers or less, about 40 micrometers or less, or about 30 micrometers or less.

[0093] The thermoformable sheet of this disclosure may use a bonding layer (sometimes called a "primer layer," etc.) to bond the layers constituting the thermoformable sheet. In one embodiment, the thermoformable sheet has a bonding layer between the surface layer and an optional decorative layer or intermediate film layer, or between the decorative layer and the intermediate film layer.

[0094] The bonding layer may include, for example, a resin having urethane bonds, a (meth)acrylic resin, an epoxy resin, or a phenoxy resin, or a blend of two or more of these resins. In one embodiment, the bonding layer includes a resin blend of a resin having urethane bonds and a phenoxy resin.

[0095] The thickness of the bonding layer can be approximately 0.1 micrometers or more, approximately 0.2 micrometers or more, or approximately 0.5 micrometers or more, approximately 10 micrometers or less, less than approximately 10 micrometers, approximately 5.0 micrometers or less, approximately 2.0 micrometers or less, approximately 1.0 micrometer or less, approximately 0.5 micrometers or less, or less than approximately 0.5 micrometers.

[0096] The thermoformed sheet may optionally include an intermediate film layer interposed between, for example, the surface layer and the second adhesive layer, between the surface layer and the decorative layer, or between the decorative layer and the second adhesive layer. The intermediate film layer can increase the strength of the thermoformed sheet.

[0097] As the intermediate film layer, for example, a resin film of a resin having urethane bonds, polyolefin such as polyvinyl chloride, polyethylene, or polypropylene, polyester such as polyethylene terephthalate or polybutylene terephthalate, (meth)acrylic polymer, or fluorine polymer can be used. The intermediate film layer is preferably thermoplastic. In one embodiment, the intermediate film layer contains a water-based resin having urethane bonds.

[0098] The thickness of the intermediate film layer can be approximately 5.0 micrometers or more, approximately 10 micrometers or more, or approximately 15 micrometers or more, approximately 200 micrometers or less, approximately 100 micrometers or less, or approximately 50 micrometers or less.

[0099] The thermoformed sheets of this disclosure can typically have a release liner applied to the first adhesive layer. Examples of release liners include paper; plastic materials such as polyethylene, polypropylene, polyester (e.g., PET), and cellulose acetate; and paper coated with such plastic materials. These liners may have a surface that has been treated with a release agent such as silicone.

[0100] The thickness of the release liner can generally be about 5 micrometers or more, about 15 micrometers or more, or about 25 micrometers or more, and can be about 500 micrometers or less, about 300 micrometers or less, or about 250 micrometers or less.

[0101] The thermoformed sheet of this disclosure may be, for example, a single sheet or a roll wound into a roll.

[0102] A thermoformable sheet can be manufactured, for example, by the following procedure: Prepare a second adhesive composition, apply the second adhesive layer composition onto a thermoplastic resin film as a surface layer, and heat-dry as necessary to form a second adhesive layer. Next, prepare a first adhesive composition, apply the first adhesive layer composition on top of the second adhesive layer, and heat-dry as necessary to form a first adhesive layer. In this way, a thermoformable sheet can be obtained. A release liner may be laminated onto the first adhesive layer of the thermoformable sheet to protect the first adhesive layer.

[0103] In the manufacturing of the thermoformed sheet described above, after forming the first adhesive layer and the second adhesive layer on the release liner, a thermoplastic resin film may be heat-laminated as a surface layer by bringing it into contact with the exposed surface of the second adhesive layer, or the resin component of the surface layer may be melt-extruded onto the exposed surface of the second adhesive layer.

[0104] In another embodiment, the thermoformed sheet may also be manufactured by, for example, the following procedure: Prepare a decorative layer composition and apply it onto a release liner, and heat-dry it as needed to form a decorative layer. Prepare an intermediate film layer composition and apply it to the exposed surface of the decorative layer, and heat-dry it as needed to form an intermediate film layer. Prepare a bonding layer composition and apply it onto a carrier film, and heat-dry it as needed to form a bonding layer. Heat-laminate the exposed surface of the bonding layer and the exposed surface of the intermediate film layer, and then remove the carrier film. As a surface layer, heat-laminate a thermoplastic resin film to the exposed surface of the bonding layer. Prepare a second adhesive composition, remove the release liner to expose the decorative layer, and then apply the second adhesive layer composition onto the decorative layer, and heat-dry it as needed to form a second adhesive layer. Next, prepare a first adhesive composition and apply the first adhesive layer composition onto the second adhesive layer, and heat-dry it as needed to form a first adhesive layer. In this way, a thermoformed sheet can be obtained. A release liner may be laminated onto the first adhesive layer of the thermoformed sheet to protect the first adhesive layer.

[0105] In the manufacture of the thermoformed sheet described above, after forming the decorative layer, instead of forming an intermediate film layer and a bonding layer, a thermoplastic resin film may be brought into contact with the exposed surface of the decorative layer and heat-laminated as a surface layer, or the resin component of the surface layer may be melt-extruded onto the exposed surface of the decorative layer. In the manufacture of the thermoformed sheet described above, the first adhesive layer and the second adhesive layer may be formed on a release liner instead of on the decorative layer, and the exposed surface of the decorative layer and the exposed surface of the second adhesive layer may be brought into contact and laminated at room temperature or heat-laminated.

[0106] The total thickness of the thermoformed sheet, excluding the thickness of the release liner, can be, for example, approximately 30 micrometers or more, approximately 80 micrometers or more, or approximately 120 micrometers or more, and can be approximately 600 micrometers or less, approximately 400 micrometers or less, or approximately 350 micrometers or less.

[0107] The thermoformed sheet of this disclosure exhibits a tensile strength of approximately 3 N / 50 mm to approximately 240 N / 50 mm when stretched to 200% at 95°C. Further enhancement of the thermoformed sheet's tensile strength improves its adhesion to the adherend (peel resistance) and its resistance to opening. Such tensile strength in the thermoformed sheet can be appropriately determined by adjusting, for example, the form (e.g., film), thickness, and material of the surface layer, or the form, thickness, and material of any additional layer (e.g., an intermediate film layer). Here, in this disclosure, 200% stretching means the state in which the film is stretched to 200% of its original length (twice the original length), with the original length being 100%. The specific measurement conditions for the tensile strength in this disclosure are described in "4. Tensile Strength at 200% Elongation" of the Examples.

[0108] The tensile strength of a thermoformed sheet when stretched to 200% at 95°C can be approximately 5N / 50mm or more, approximately 7N / 50mm or more, or approximately 9N / 50mm or more, and can be approximately 220N / 50mm or less, approximately 200N / 50mm or less, approximately 180N / 50mm or less, approximately 160N / 50mm or less, approximately 140N / 50mm or less, approximately 120N / 50mm or less, approximately 100N / 50mm or less, or approximately 80N / 50mm or less.

[0109] In one embodiment, the thermoformed sheet of this disclosure exhibits a tensile strength of approximately 1 N / 50 mm to approximately 140 N / 50 mm when stretched to 200% at 120°C. Further improvement of the thermoformed sheet's tensile strength (resistance to peeling) and resistance to opening can be achieved. Such tensile strength in the thermoformed sheet can be appropriately set, for example, by adjusting the form (e.g., film), thickness, and material of the surface layer, or the form, thickness, and material of any additional layer (e.g., an intermediate film layer).

[0110] The tensile strength of a thermoformed sheet when stretched to 200% at 120°C can be approximately 2N / 50mm or more, approximately 3N / 50mm or more, approximately 4N / 50mm or more, or approximately 5N / 50mm or more, and can be approximately 120N / 50mm or less, approximately 100N / 50mm or less, approximately 80N / 50mm or less, approximately 60N / 50mm or less, or approximately 50N / 50mm or less.

[0111] In one embodiment, the thermoformed sheet of the present disclosure is heated to 165°C ± 5°C, and when the area of ​​the thermoformed sheet before stretching is set to 100%, it is stretched to 200% by area ratio using a vacuum pressure forming machine and bonded to a PC-ABS board, cut into a grid with a width of 40 mm, and after being left at 95°C for 144 hours, the opening of the cuts (mouth opening) is approximately 1.0 mm or less. Preferably, the opening of the cuts is approximately 0.8 mm or less, more preferably approximately 0.5 mm or less. The opening of the cuts represents the heat resistance of the thermoformed sheet, specifically the behavior of the thermo-shrinkage of the thermoformed sheet. The smaller the value of the opening of the cuts, the less the thermoformed sheet shrinks even in a high-temperature environment, and the better the adhesion to the adherend and the appearance of the thermoformed sheet can be maintained. The specific measurement conditions for the opening of the cuts are as described in "3. Heat Shrinkage" of the Examples.

[0112] In one embodiment, a thermoformed sheet is heated to 165°C ± 5°C, and when the area of ​​the thermoformed sheet before stretching is set to 100%, it is stretched to 200% by area ratio using a vacuum pressure forming machine and bonded to a PC-ABS board. When cut into strips with a width of 10 mm and peeled at 23°C and a peeling speed of 200 mm / min at 180 degrees, the adhesive strength is approximately 6.4 N / 10 mm or more. The adhesive strength is preferably approximately 6.8 N / 10 mm or more, and more preferably approximately 7.2 N / 10 mm or more. The adhesive strength is less than the force required for cohesive failure of the adherend or thermoformed sheet, and is generally about 20 N / 10 mm or less, or about 15 N / 10 mm or less. The specific measurement conditions for the adhesive strength are as described in "2. Adhesion Strength" of the Examples.

[0113] According to one embodiment of the present disclosure, an article is provided in which the above-mentioned thermoformed sheet is bonded to a support member (adherent). Examples of such articles include a substantially flat article before molding, in which the thermoformed sheet is bonded to a support member such as a polycarbonate plate, or an article having a three-dimensional shape obtained by further molding such a substantially flat article, or an article having a three-dimensional shape obtained by bonding the thermoformed sheet to a support member having a curved surface or the like. In the present disclosure, "three-dimensional shape" typically refers to a three-dimensional shape in which the Z axis is added to a two-dimensional shape (a planar shape with only the X and Y axes).

[0114] Articles having a three-dimensional shape are preferably manufactured by applying the above-described thermoformed sheet to a support member having a three-dimensional shape, from the viewpoint of productivity and other factors. The application of the thermoformed sheet to this support member is preferably carried out by vacuum forming (VT) or dual vacuum thermoforming (DVT) from the viewpoint of obtaining a highly accurate article. The thermoformed sheet of this disclosure can be suitably used for vacuum forming or vacuum pressure forming accompanied by stretching.

[0115] There are no particular restrictions on the support member, and examples include at least one selected from the group consisting of (meth)acrylic resin members (e.g., polymethyl methacrylate (PMMA) resin members), polycarbonate resin members (PC resin members), acrylonitrile-butadiene-styrene copolymer members (ABS members), PC-ABS members, and electrodeposited coating members. These can be used individually or in combination of two or more. In particular, from the viewpoint of adhesion to the thermoformed sheet (anti-peeling properties) and resistance to opening, it is preferable that the support member be at least one selected from the group consisting of PC-ABS members and electrodeposited coating members.

[0116] A primer treatment may be applied to the surface of the support member. However, since primer treatment generally uses organic solvents, there is a risk of deteriorating the working environment or causing dust to adhere to the primer-treated surface, resulting in an unsightly appearance. The thermoformed sheet of this disclosure can exhibit excellent adhesion (anti-peeling properties) and resistance to opening even if a primer treatment is not applied to the surface of the support member to which it is adhered. Therefore, from the viewpoint of obtaining a good working environment and an appearance of the product, it is advantageous not to apply a primer treatment to the surface of the support member.

[0117] The support member may be transparent, translucent, or opaque in whole or in part in the visible range in order to provide the desired appearance.

[0118] There are no particular restrictions on the thickness of the support member; for example, it can be approximately 0.2 mm or more, approximately 0.5 mm or more, approximately 1.0 mm or more, or approximately 1.5 mm or more, and it can be approximately 3.0 mm or less, approximately 2.5 mm or less, or approximately 2.0 mm or less.

[0119] Articles to which the thermoformable sheets of this disclosure are applied can be used for a variety of purposes. Such uses include, for example, signs (e.g., internally illuminated signs and externally illuminated signs); signs (e.g., internally illuminated signs and externally illuminated signs); various interior or exterior parts, such as interior or exterior parts for vehicles such as automobiles, trains, aircraft, and ships (e.g., roof members, pillar members, door trim members, instrument panel members, front members such as hoods, bumper members, fender members, side sill members, and interior panel members); building materials (e.g., doors); electrical appliances such as personal computers, smartphones, mobile phones, refrigerators, and air conditioners; stationery; furniture; desks; and various containers such as cans. Among these, articles to which the thermoformable sheets of this disclosure are applied are particularly suitable for use as interior or exterior parts for vehicles. Examples of vehicles include automobiles such as trucks, buses, and passenger cars; two-wheeled vehicles such as motorcycles and scooters; bicycles; trains; pleasure boats; yachts; motorboats; and other vessels.

[0120] The following describes, with reference to Figure 2, an exemplary method for forming an article by applying a thermoformed sheet to a support member using the vacuum pressure forming method (DVT method).

[0121] As shown in Figure 2(A), the exemplary vacuum pressure forming machine 30 has a first vacuum chamber 31 and a second vacuum chamber 32, respectively, located above and below the first vacuum chamber. A jig for setting the thermoforming sheet 10 to be attached to the support member 40, which is the object to be formed, is provided between the upper and lower vacuum chambers. In the lower first vacuum chamber 31, a partition plate 34 and a base 33 are installed on a lifting platform 35 (not shown in Figure 2(A)) that can be raised and lowered, and the support member 40, such as a three-dimensional object, is set on this base 33. Commercially available vacuum pressure forming machines, such as a double-sided vacuum forming machine (Fuse Vacuum Co., Ltd.), can be used as such a vacuum pressure forming machine.

[0122] As shown in Figure 2(A), first, with the first vacuum chamber 31 and the second vacuum chamber 32 of the vacuum pressure forming machine 30 released to atmospheric pressure, the thermoforming sheet 10 is set between the upper and lower vacuum chambers. In the first vacuum chamber 31, the support member 40 is set on the base 33.

[0123] Next, as shown in Figure 2(B), the first vacuum chamber 31 and the second vacuum chamber 32 are closed and the pressure is reduced in each chamber to create a vacuum inside each chamber (for example, approximately 0 atm, assuming atmospheric pressure is 1 atm). After that, or simultaneously with the reduction in pressure, the thermoforming sheet is heated.

[0124] Next, as shown in Figure 2(C), the lifting platform 35 is raised to push the support member 40 up to the second vacuum chamber 32. Heating can be performed, for example, by an IR lamp heater (not shown) incorporated into the ceiling of the second vacuum chamber 32. The heating temperature can generally be about 50°C or higher and about 180°C or lower, preferably about 130°C or higher and about 160°C or lower. The vacuum level of the reduced pressure atmosphere can be about 0.10 atm or lower, about 0.05 atm or lower, or about 0.01 atm or lower, with atmospheric pressure being 1 atm.

[0125] The heated thermoformed sheet 10 is pressed against the surface of the support member 40 and stretched. Subsequently, or simultaneously with stretching, the second vacuum chamber 32 is pressurized to an appropriate pressure (for example, about 3 atm to about 1 atm), as shown in Figure 2(D). Due to the pressure difference, the thermoformed sheet 10 adheres closely to the exposed surface of the support member 40, stretches to conform to the three-dimensional shape of the exposed surface, and forms a covering that adheres closely to the surface of the support member. At least a portion of the thermoformed sheet 10 may be stretched by, for example, about 4 times or more, about 4.5 times or more, or about 5 times or more in area ratio when stretched to conform to the three-dimensional shape of the support member 40. Alternatively, after depressurizing and heating in the state shown in Figure 2(B), the second vacuum chamber 32 can be pressurized immediately to cover the exposed surface of the support member 40 with the thermoformed sheet 10.

[0126] Subsequently, the upper and lower first vacuum chambers 31 and second vacuum chambers 32 are opened to atmospheric pressure again, and the support member 40 covered with the thermoformed sheet 10 is removed. As shown in Figure 2(E), the edges of the thermoformed sheet 10 that are in close contact with the surface of the support member 40 are trimmed, and the DVT process is completed. In this way, an article 42 with good wrap-around covering is obtained, in which the thermoformed sheet 10 wraps around to the back surface 41 at the end of the support member 40 and neatly covers the exposed surface. [Examples]

[0127] The following examples illustrate specific embodiments of the present disclosure, but the present invention is not limited thereto. All parts and percentages are by mass unless otherwise specified. Numerical values ​​include errors inherent to the measurement principle and measuring device. Numerical values ​​are shown with significant figures after normal rounding.

[0128] Synthesis of carboxyl group-containing (meth)acrylic polymers (polymer A) 94 parts by mass of n-butyl acrylate (BA) and 6 parts by mass of acrylic acid (AA) were dissolved in a mixed solvent of 100 parts by mass of toluene and 100 parts by mass of ethyl acetate. 0.2 parts by mass of 2,2'-azobis(2,4-dimethylvaleronitrile) (trade name V-65, Fujifilm Wako Pure Chemical Industries, Ltd. (Osaka, Osaka, Japan)) were added as a polymerization initiator. The mixture was then reacted at 50°C for 24 hours under a nitrogen atmosphere to obtain a toluene / ethyl acetate mixed solution of polymer A (solid content 33% by mass). The weight-average molecular weight of polymer A was 760,000, and the glass transition temperature (Tg) calculated from the FOX formula was -48°C.

[0129] Synthesis of amino group-containing (meth)acrylic polymers (polymer B) 60 parts by mass of methyl methacrylate (MMA), 34 parts by mass of n-butyl methacrylate (BMA), and 6 parts by mass of dimethylaminoethyl methacrylate (DMAEMA) were dissolved in 150 parts by mass of ethyl acetate. 0.6 parts by mass of dimethyl-2,2'-azobis(2-methylpropionate) (trade name V-601, Fujifilm Wako Pure Chemical Industries, Ltd. (Osaka, Osaka, Japan)) was added as a polymerization initiator. The mixture was then reacted under a nitrogen atmosphere at 65°C for 24 hours to obtain an ethyl acetate solution of polymer B (solid content 39% by mass). The weight-average molecular weight of polymer B was 68,000, and the glass transition temperature (Tg) calculated from the FOX formula was 63°C.

[0130] The products used in this example are shown in Table 1 below.

[0131] [Table 1]

[0132] <Comparative Example 1> A two-layer thermoformable sheet was prepared using the following procedure. The second adhesive composition E1 shown in Table 3 was applied to a 75-micrometer thick Technoloy (trademark) S014G surface layer using a knife coater, and the sheet was placed in an 80°C hot air oven for 10 minutes to form a 40-micrometer thick second adhesive layer, thereby obtaining a thermoformable sheet of Comparative Example 1 that does not have a first adhesive layer.

[0133] <Example 1> A three-layer thermoformable sheet was prepared using the following procedure. The second adhesive composition E1 shown in Table 3 was applied to a 75-micrometer thick Technoloy (trademark) S014G surface layer using a knife coater, and the sheet was placed in an 80°C hot air oven for 10 minutes to form a 40-micrometer thick second adhesive layer.

[0134] The first adhesive composition E1 shown in Table 2 was applied onto the second adhesive layer using a knife coater, and the mixture was placed in an 80°C hot air oven for 10 minutes to form a first adhesive layer with a thickness of 1.0 micrometer, thereby obtaining the thermoformed sheet of Example 1.

[0135] <Examples 2-4, 9-11, and Comparative Example 2> Thermoformed sheets for Examples 2-4, Examples 9-11, and Comparative Example 2 were obtained using the same procedure as in Example 1, except that the thickness of the first adhesive layer and / or the second adhesive layer was as shown in Table 5.

[0136] <Example 5, Comparative Example 3, Comparative Example 5, and Comparative Example 6> Thermoformable sheets for Example 5, Comparative Example 3, Comparative Example 5, and Comparative Example 6 were obtained using the same procedure as in Example 3, except that the first adhesive composition was E2, C1, C2, or C3 from Table 2.

[0137] <Examples 6-8, Comparative Example 7 and Comparative Example 8> Except for the surface layer being as described in Table 5, the thermoformed sheets of Examples 6 to 8, Comparative Example 7, and Comparative Example 8 were obtained using the same procedure as in Example 3.

[0138] <Example 12> A thermoformed sheet prepared using the same procedure as in Example 3 was stored for 40 days at 23°C and 60% RH to obtain the thermoformed sheet of Example 12.

[0139] <Comparative Example 4> A two-layer thermoformable sheet was prepared using the following procedure. The first adhesive composition E1 shown in Table 2 was applied to a 75-micrometer thick Technoloy (trademark) S014G surface layer using a knife coater, and the sheet was placed in an 80°C hot air oven for 10 minutes to form a 5.0-micrometer thick first adhesive layer, thereby obtaining a thermoformable sheet of Comparative Example 4 that does not have a second adhesive layer.

[0140] [Table 2]

[0141] [Table 3]

[0142] [Table 4]

[0143] The thermoformable sheets were evaluated based on the following criteria.

[0144] 1.DVT formability The following were used as support members.

[0145] A.PC-ABS board A 3mm thick, 150mm x 150mm square PC-ABS plate test panel (product name "Flat Test Piece", manufactured by Technopolymer using black PC-ABS resin CK43, MC Yamasan Polymers Co., Ltd. (Chuo-ku, Tokyo, Japan)) was cut into a 70mm x 150mm rectangle to obtain the support members.

[0146] B. Electrodeposited coated steel sheet The support members were 1mm thick, 70mm x 150mm black cationic electrodeposition coated steel sheets (JIS G 3141 (SPCC SD), Testpiece Co., Ltd. (Sagamihara City, Kanagawa Prefecture, Japan)).

[0147] Using the DVT method, the thermoformed sheet was stretched by 200% by area ratio and attached to the support member using the following procedure.

[0148] A double-sided vacuum forming machine NGF0709 (Fuse Vacuum Co., Ltd., Habikino City, Osaka Prefecture, Japan) was used as the vacuum pressure forming machine. Figure 3A shows a schematic cross-sectional view of the vacuum pressure forming machine before stretching. The first vacuum chamber 31 and the second vacuum chamber 32 of the vacuum pressure forming machine 30 were separated from each other by the lower boiler 311, the lower boiler frame 312, the upper boiler 321, the upper boiler frame 322, and the thermoforming sheet 10 sandwiched between the lower boiler frame 312 and the upper boiler frame 322. An IR lamp heater 323 for heating was attached to the inner wall of the upper boiler 321 at the ceiling of the second vacuum chamber 32. The opening of the lower boiler frame 312 was a 260 mm x 260 mm square.

[0149] A rectangular, open-topped, rectangular stretching jig 314, with an inner dimension the same size as the opening of the lower boiler frame 312, was placed on the lower boiler table 313 located at the bottom of the lower boiler 311. The height of the stretching jig 314 was 60 mm, and it was confirmed in advance that the thermoformed sheet 10 would be attached to the support member 40 in a state where it had been stretched by 200% in area.

[0150] A rectangular support member 40 measuring 70 mm x 150 mm was placed on the lower boiler table 313 and inside the stretching well-shaped jig 314, in a position where it had been confirmed in advance that the thermoformed sheet 10 would be attached to the support member 40 when stretched by 200% in area ratio. Figure 3B shows the placement of the base material in a top view. As shown in Figure 3B, the support members 40 were placed at four locations 90 mm away from the center of the stretching well-shaped jig 314, with their centers positioned accordingly. The circles shown by dashed lines in Figure 3B represent the positions where the thermoformed sheet 10 will be attached to the support member 40 when stretched by 200% in area ratio.

[0151] The thermoformed sheet 10 was cut into a 300mm x 300mm square and placed on the lower boiler frame 312. The thickness of the lower boiler frame 312 was 20mm. Therefore, the distance between the thermoformed sheet 10 and the support member 40 was 80mm, which is the sum of the thickness of the lower boiler frame 312 (20mm) and the height of the stretching well-shaped jig 314 (60mm).

[0152] After installing the support member 40 and the thermoforming sheet 10, the upper boiler 321 and upper boiler frame 322 were lowered, and the thermoforming sheet 10, which was placed on the lower boiler frame 312, was sandwiched between the upper boiler frame 322 and the lower boiler frame 312. Then, while reducing the pressure inside the first vacuum chamber 31 and the second vacuum chamber 32, the thermoforming sheet 10 was heated with the IR lamp heater 323 until it reached the molding temperature of 165°C ± 5°C. At this time, a vacuum state (2-4 kPa) was reached before reaching the molding temperature. The molding temperature was a value obtained based on the set temperature of the vacuum pressure forming machine 30 and the correspondence between the set temperature of the vacuum pressure forming machine 30 and the actual temperature of the thermoforming sheet 10, which was created in advance using a procedure described later.

[0153] DVT molding was started when the molding temperature was reached. The lower boiler table 313 was raised until the stretching well-shaped jig 314 contacted the lower boiler frame 312. While maintaining the vacuum state inside the first vacuum chamber 31, the internal pressure of the second vacuum chamber 32 was set to 200-205 kPa, creating a pressure difference between the first vacuum chamber 31 and the second vacuum chamber 32, thereby stretching the thermoformed sheet 10 and attaching it to the support member 40. Figure 3C shows a schematic cross-sectional view of the vacuum pressure forming machine after stretching. In the central part of the support member 40, the thermoformed sheet 10 was stretched by 200% in area ratio and attached.

[0154] After returning the first vacuum chamber 31 and the second vacuum chamber 32 to atmospheric pressure, the support member 40 to which the stretched thermoformed sheet 10 was attached was removed. By trimming the excess thermoformed sheet 10 along the edge of the support member 40 using a utility knife, an evaluation sample for DVT moldability was obtained.

[0155] It is generally known that there is a difference between the set temperature of the vacuum pressure forming machine and the actual temperature of the thermoformed sheet heated inside the vacuum pressure forming machine. Therefore, in this embodiment, the correspondence between the set temperature of the vacuum pressure forming machine and the actual temperature of the thermoformed sheet was determined in advance, and the actual temperature of the thermoformed sheet during DVT forming was considered to be a value obtained based on the set temperature of the vacuum pressure forming machine and the above correspondence.

[0156] The actual temperature of the thermoformed sheet during DVT molding was measured using a temperature / voltage measurement unit NR-TH08 and a multi-input data logger NR-500 (both manufactured by Keyence Corporation, Osaka, Japan) and a thermocouple (symbol 0.1×1P K-2-H-J2(KH), wire: K type, manufactured by Ninomiya Electric Wire Industry Co., Ltd., Sagamihara, Kanagawa, Japan).

[0157] To prevent the metal part of the thermocouple, which is the measurement area, from coming into contact with the thermoforming sheet 10, the thermocouple was attached to the surface of the thermoforming sheet 10 with heat-resistant tape. The thermoforming sheet 10 was then placed on the lower boiler frame 312 with the side to which the thermocouple was attached facing upwards.

[0158] The upper kettle 321 and the upper kettle frame 322 were lowered, and the thermoformed sheet 10 installed on the lower kettle frame 312 was sandwiched between the upper kettle frame 322 and the lower kettle frame 312. Then, the thermoformed sheet 10 was heated with the IR lamp heater 323. The set temperature of the vacuum pressure thermoforming machine when the measured value of the thermocouple reached 165 ± 5°C was 145°C. Based on this correspondence, during DVT forming, by setting the temperature of the vacuum pressure thermoforming machine to 145°C, it was considered that the thermoformed sheet 10 was heated to 165 ± 5°C.

[0159] 2. Adhesive strength The test pieces adhered under the same conditions as the DVT formability were cut into strips with a width of 10 mm, and the adhesive strength when performing 180-degree peeling at a temperature of 23°C and a peeling speed of 200 mm / min was measured using a tensile testing machine (Tensilon (registered trademark) universal testing machine, model number: RTC-1210A, A&D Company, Limited (Toshima-ku, Tokyo, Japan)). The measurement was performed twice to obtain the average value. For example, in the case of applications replacing the painting of automotive exterior parts, the adhesive strength is required to be 6.4 N / 10 mm or more.

[0160] 3. Heat shrinkage A grid-shaped cut with a width of 40 mm as shown in Fig. 4 was made in the center of the test piece adhered under the same conditions as the DVT formability, and it was placed at 95°C for 144 hours (6 days). The opening of the cut was measured at 4 locations, and the average of the 4 measured values was used as an index of heat shrinkage. If the opening of the cut (mouth opening) was 1.0 mm or less, it was considered qualified; if it exceeded 1.0 mm, it was considered unqualified.

[0161] 4. Tensile strength at 200% elongation A thermoformed sheet was cut to approximately 100 mm in length and 50 mm in width. Kapton® film, 50 mm wide, was attached to both sides of the thermoformed sheet with a 50 mm gap along its length, creating a test sample where the two short sides of the thermoformed sheet were sandwiched between the Kapton® film. The test sample was fixed to a tensile testing machine (Tensilon® universal testing machine, model number: RTC-1210A, A&D Company, Limited (Toshima-ku, Tokyo, Japan)) with the chucks spaced 55 mm apart, so that the Kapton® film was in contact with the chucks. A constant temperature chamber was placed to cover the entire chuck area, and measurement began when the temperature display inside the chamber reached 95°C or 120°C. The tensile strength was measured when the thermoformed sheet was stretched to 200% elongation (twice its original length) at a temperature of 95°C or 120°C and a tensile speed of 300 mm / min. Two measurements were taken at each temperature and the average value was calculated.

[0162] Table 5 shows the evaluation results for the thermoformed sheets. Here, in the layer structure, "A" refers to the layer structure of the first adhesive layer / second adhesive layer / film (surface layer), "B" refers to the layer structure of the second adhesive layer / film (surface layer), and "C" refers to the layer structure of the first adhesive layer / film (surface layer).

[0163] [Table 5]

[0164] It will be apparent to those skilled in the art that the above embodiments and examples can be modified in various ways without departing from the basic principles of the present invention. Furthermore, it will be apparent to those skilled in the art that various improvements and modifications of the present invention can be implemented without departing from the spirit and scope of the invention. [Explanation of symbols]

[0165] 10 Thermoformable Sheets 12 Surface layer 14 Second adhesive layer 16 1st adhesive layer 20 Release Liner 30 Vacuum pressure forming machine 31 1st vacuum chamber 311 Lower pot 312 Lower boiler frame 313 Lower boiler table 314 Well-shaped jig for extension 32 Second vacuum chamber 321 Upper pot 322 Upper boiler frame 323 IR Lamp Heater 33 Pedestal 34 partition plates 35 Elevating platform 40 Support member 41 Back part 42 Goods Some embodiments of this disclosure are described in the following sections [1]-

[10] . [Item 1] A thermoformable sheet comprising a first adhesive layer, a second adhesive layer, and a surface layer in that order, The first adhesive layer contains 65% by mass or more of an acyclic aliphatic isocyanate polymer blocked with a blocking agent that begins to dissociate at temperatures below 160°C, and has a thickness of 0.5 micrometers or more and 13 micrometers or less. A thermoformable sheet having a tensile strength of 3N / 50mm to 240N / 50mm when stretched to 200% at 95℃. [Item 2] The thermoformable sheet according to item 1, wherein the acyclic aliphatic isocyanate polymer is a polymer obtained by blocking a polymer of an acyclic aliphatic isocyanate compound with the blocking agent, and the acyclic aliphatic isocyanate compound is at least one selected from the group consisting of 1,6-hexamethylene diisocyanate and its modified forms. [Item 3] A thermoformable sheet as described in item 1 or 2, wherein the tensile strength when stretched to 200% at 120°C is 1 N / 50 mm or more and 140 N / 50 mm or less. [Item 4] A thermoforming sheet according to any one of items 1 to 3, wherein the second adhesive layer is a heat-sensitive adhesive layer. [Item 5] A thermoformable sheet according to any one of items 1 to 4, wherein the thickness of the second adhesive layer is 10 micrometers or more and 140 micrometers or less. [Item 6] A thermoformed sheet as described in any one of items 1 to 5, wherein the thermoformed sheet is heated to 165°C ± 5°C, and when the area of ​​the thermoformed sheet before stretching is taken as 100%, it is stretched to 200% by area ratio using a vacuum pressure forming machine, bonded to a PC-ABS board, cut into a grid pattern with a width of 40 mm, and the gap between the cuts after being left at 95°C for 144 hours is 1.0 mm or less. [Item 7] An article in which a thermoformed sheet described in any one of items 1 to 6 is bonded to a support member. [Item 8] Articles as described in item 7, having a three-dimensional shape. [Item 9] Articles that are interior or exterior parts of a vehicle, as specified in item 7 or 8. [Item 10] The article according to any one of items 7 to 9, wherein the support member is at least one selected from the group consisting of PC-ABS material and electrodeposited coating material.

Claims

1. A thermoformable sheet comprising a first adhesive layer, a second adhesive layer, and a surface layer in this order, The first adhesive layer contains 65% by mass or more of an acyclic aliphatic isocyanate polymer blocked with a blocking agent that begins to dissociate at temperatures below 160°C, and has a thickness of 0.5 micrometers or more and 13 micrometers or less. The acyclic aliphatic isocyanate polymer is at least one selected from the group consisting of polymers of acyclic aliphatic isocyanate compounds and modified acyclic aliphatic isocyanate compounds that are blocked by a blocking agent that initiates dissociation at less than 160°C, and the modified compound is an isocyanurate, biuret, trimer, ethylene glycol adduct, propylene glycol adduct, trimethylolpropane adduct, ethanolamine adduct, allophanate, uretdione, polyester polyol adduct, polyether polyol adduct, polyamide adduct, or polyamine adduct. The second adhesive layer is a (meth)acrylic-based heat-sensitive adhesive layer or a polyurethane-based heat-sensitive adhesive layer. A thermoformable sheet having a tensile strength of 3 N / 50 mm or more and 240 N / 50 mm or less when stretched to 200% at 95°C.

2. The thermoformable sheet according to claim 1, wherein the acyclic aliphatic isocyanate compound is 1,6-hexamethylene diisocyanate.

3. The thermoformable sheet according to claim 1 or 2, wherein the tensile strength when stretched to 200% at 120°C is 1 N / 50 mm or more and 140 N / 50 mm or less.

4. The thermoformable sheet according to any one of claims 1 to 3, wherein the thickness of the second adhesive layer is 10 micrometers or more and 140 micrometers or less.

5. The thermoformed sheet according to any one of claims 1 to 4, wherein the thermoformed sheet is heated to 165°C ± 5°C, and when the area of ​​the thermoformed sheet before stretching is taken as 100%, it is stretched to 200% by area ratio using a vacuum pressure forming machine and bonded to a PC-ABS board, cut into a grid pattern with a width of 40 mm, and the opening of the cuts after being left at 95°C for 144 hours is 1.0 mm or less.

6. An article in which a thermoformed sheet according to any one of claims 1 to 5 is bonded to a support member.

7. The article according to claim 6, having a three-dimensional shape.

8. The article according to claim 6 or 7, which is an interior or exterior part of a vehicle.

9. The article according to any one of claims 6 to 8, wherein the support member is at least one selected from the group consisting of PC-ABS material and electrodeposited coating material.

Images