Polycarbonate resin laminate for heat bending, and method for manufacturing polycarbonate resin laminate for heat bending

Abstract

In this polycarbonate resin laminate (10) for heat bending, a base material layer (1) containing polycarbonate resin and a hard coat layer (2) are laminated, a weather-resistant layer (3) is interposed between the base material layer (1) and the hard coat layer (2), and the weather-resistant layer (3) contains polycarbonate resin and an ultraviolet absorber.

Description

Polycarbonate resin laminate for heat bending, and method for manufacturing polycarbonate resin laminate for heat bending

[0001] The present invention relates to a polycarbonate resin laminate for hot bending and a method for manufacturing a polycarbonate resin laminate for hot bending. More specifically, the present invention relates to a polycarbonate resin laminate for hot bending, a curved member, a method for manufacturing a polycarbonate resin laminate for hot bending, and a method for manufacturing a curved member.

[0002] Polycarbonate resin is known to have high transparency, abrasion resistance, heat resistance, etc. Therefore, molded articles obtained by heat bending a polycarbonate resin sheet are suitably used, for example, as various lenses for sunglasses and ski goggles, motorcycle windshields, and vehicle window materials.

[0003] For example, Patent Document 1 (WO 2021 / 070632) discloses a polycarbonate resin laminate in which a predetermined penetration layer and a hard coat layer containing an ultraviolet absorber are laminated in this order on at least one surface of a polycarbonate resin substrate layer in order to improve abrasion resistance, heat bending property, and adhesion after heat bending. It is also disclosed that the penetration layer contains both the components of the polycarbonate resin substrate layer and the hard coat layer, thereby improving the adhesion of each layer. It is also disclosed that a method for forming the penetration layer and the hard coat layer can be achieved by applying an inorganic fine particle dispersion for forming the hard coat layer to the surface of the polycarbonate resin substrate layer to form the penetration layer and the hard coat layer simultaneously.

[0004] International Publication No. 2021 / 070632

[0005] However, conventional polycarbonate resin laminates such as those disclosed in Patent Document 1 contain an ultraviolet absorber in the hard coat layer that forms the outer surface. However, due to the resin properties of polycarbonate resin laminates, they may be used for long periods of time or exposed to harsh environments such as strong winds and dust, which makes the hard coat layer prone to wear and damage. As a result, the ultraviolet absorption effect of the conventional technology is impaired, leaving room for improvement in terms of maintaining good weather resistance.

[0006] The present inventors have conducted research into improving the weather resistance of polycarbonate resins while maintaining their inherent properties, such as abrasion resistance, and have found that by providing a weather-resistant layer containing an ultraviolet absorber below the hard coat layer, the weather-resistant layer can protect the substrate layer from ultraviolet rays even if the hard coat layer is worn, and have completed the present invention.

[0007] According to the present invention, the following polycarbonate resin laminate and related techniques are provided.

[0008] [1] A polycarbonate resin laminate for hot bending process comprising a substrate layer containing a polycarbonate resin and a hard coat layer laminated together, wherein a weathering layer is interposed between the substrate layer and the hard coat layer, and the weathering layer contains a polycarbonate resin and an ultraviolet absorber. [2] The polycarbonate resin laminate for hot bending process according to [1], wherein the content of the ultraviolet absorber in the weathering layer is 1 mass % or more and 10 mass % or less, based on the total amount of the weathering layer. [3] The polycarbonate resin laminate for hot bending process according to [1] or [2], wherein the hard coat layer contains an ultraviolet absorber of a different type from the ultraviolet absorber in the weathering layer. [4] The polycarbonate resin laminate for heat bending according to any one of [1] to [3], wherein the content of the ultraviolet absorber contained in the base layer is 1 mass % or less with respect to the total amount of the base layer. [5] The polycarbonate resin laminate for heat bending according to any one of [1] to [4], wherein the L ＊ a ＊ b ＊ a in the color system ＊ Values ​​are -6 to 1, b ＊[6] The polycarbonate resin laminate for hot bending according to any one of [1] to [5], wherein the thickness (μm) of the weather-resistant layer is 0.06 to 3.5% of the total thickness (μm) of the polycarbonate resin laminate for hot bending. [7] The polycarbonate resin laminate for hot bending according to any one of [1] to [6], wherein the thickness (μm) of the weather-resistant layer is 10 to 100 μm. [8] The polycarbonate resin laminate for hot bending according to any one of [1] to [7], wherein the ultraviolet absorber contained in the weather-resistant layer is a triazine-based ultraviolet absorber. [9] The polycarbonate resin laminate for hot bending according to any one of [1] to [8], wherein the base layer and the weather-resistant layer are laminated by co-extrusion molding.

[10] The polycarbonate resin laminate for hot bending according to any one of [1] to [9], further comprising a transition layer between the hard coat layer and the weather-resistant layer, wherein the transition layer contains at least a portion of the components of the hard coat layer and at least a portion of the components of the weather-resistant layer.

[11] The polycarbonate resin laminate for hot bending according to any one of [1] to

[10] , wherein the thickness (μm) of the hard coat layer is 1 to 20 μm.

[12] The polycarbonate resin laminate for hot bending process according to any one of [1] to

[11] , wherein the thickness (μm) of the polycarbonate resin laminate for hot bending process is 3 to 15 mm.

[13] A curved member obtained by heat bending the polycarbonate resin laminate for hot bending process according to any one of [1] to

[12] .

[14] A method for producing a polycarbonate resin laminate for hot bending processability, in which a substrate layer containing a polycarbonate resin, a weather-resistant layer, and a hard coat layer are laminated in this order, comprising the steps of: co-extruding a resin composition for the substrate layer and a resin composition for the weather-resistant layer to laminate the substrate layer and the weather-resistant layer; and applying a resin composition for the hard coat layer to a surface of the laminated weather-resistant layer opposite to the substrate layer to form a hard coat layer on the substrate layer, wherein the weather-resistant layer contains a polycarbonate resin and an ultraviolet absorber.

[15] A curved member is produced by hot bending the polycarbonate resin laminate for hot bending processability obtained by the method for producing a polycarbonate resin laminate for hot bending processability described in

[14] .

[0009] According to the present invention, a polycarbonate resin laminate having improved weather resistance is provided.

[0010] 1 is a cross-sectional view schematically showing a polycarbonate resin laminate 10 for hot bending process according to the present embodiment.

[0011] In this specification, the notation "a to b" in the description of a numerical range means from a to b, unless otherwise specified. For example, "1 to 5 mass%" means "1 mass% to 5 mass%." Furthermore, the lower limit and upper limit of a numerical range can be arbitrarily combined with the lower limit and upper limit of another numerical range.

[0012] Unless otherwise specified, each of the components and materials exemplified in this specification may be used alone or in combination of two or more. In this specification, the thickness of each layer refers to the thickness of one layer.

[0013] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The drawings are for illustrative purposes only, and the shapes and dimensional ratios of the components in the drawings do not necessarily correspond to actual products.

[0014] <Polycarbonate resin laminate for hot bending> Fig. 1 is a cross-sectional view schematically showing a polycarbonate resin laminate for hot bending 10 according to this embodiment. The polycarbonate resin laminate for hot bending 10 is in the form of a plate, sheet, or film.

[0015] The polycarbonate resin laminate 10 for hot bending process comprises a substrate layer 1 containing a polycarbonate resin and a hard coat layer 2 laminated together, with a weather-resistant layer 3 interposed between the substrate layer 1 and the hard coat layer 2, the weather-resistant layer 3 containing a polycarbonate resin and an ultraviolet absorber. That is, since the weather-resistant layer 3 interposed between the substrate layer 1 and the hard coat layer 2 contains an ultraviolet absorber, the weather-resistant layer 3 maintains weather resistance and can protect the substrate layer 1 even if the hard coat layer 2 is worn or damaged.

[0016] In this embodiment, the polycarbonate resin laminate 10 for hot bending has a weather-resistant layer 3 and a hard coat layer 2 on both sides of the substrate layer 1, with one side of the weather-resistant layer 3 in contact with the substrate layer 1 and the other side in contact with the hard coat layer 2. As a result, the substrate layer 1 is not exposed on the surface of the polycarbonate resin laminate 10 for hot bending, which prevents the substrate layer 1 from being hit by sand, dust, flying stones, rain, etc., and from being abraded by other members, etc.

[0017] Furthermore, in conventional techniques in which an ultraviolet absorber is incorporated into a substrate layer, the thickness of the substrate layer is relatively thicker than that of other layers such as the hard coat layer, resulting in a low concentration of ultraviolet absorber, and the substrate layer tends to yellow due to ultraviolet rays. Furthermore, yellowing of the substrate layer also yellows the entire laminate, tending to degrade the appearance of the laminate. In contrast, the polycarbonate resin laminate 10 for hot bending process of the present embodiment contains an ultraviolet absorber in the weather-resistant layer 3, which is thinner than the substrate layer 1, and can therefore contain a high concentration of ultraviolet absorber. Therefore, the weather-resistant layer 3 can effectively absorb ultraviolet rays that reach the substrate layer 1, making it easier to improve the weather resistance of the polycarbonate resin laminate 10 for hot bending process. Furthermore, even if the weather-resistant layer 3 yellows due to ultraviolet rays, the thin thickness of the weather-resistant layer 3 minimizes the impact on the appearance of the polycarbonate resin laminate 10 for hot bending process, making it easier to maintain a good appearance.

[0018] L of polycarbonate resin laminate 10 for hot bending processing ＊ a ＊ b ＊ a in the color system ＊ The value is preferably −6 to 1, more preferably −5 to 0, and even more preferably −4.5 to −1. ＊ a ＊ b ＊ b in the color system ＊ The value is preferably −8 to 2.5, more preferably −6.5 to 1.5, and even more preferably −3 to 1. ＊ a ＊ b ＊ a in the color system ＊ value and b ＊ By setting the value within the above range, the polycarbonate resin laminate 10 for hot bending process can maintain a good balance between good appearance and transparency.

[0019] L of polycarbonate resin laminate 10 for hot bending processing ＊ a ＊ b ＊ a in the color system ＊ value and b ＊ The value can be adjusted by selecting and combining the combination of materials for the substrate layer 1, hard coat layer 2 and weather-resistant layer 3 and known manufacturing methods.

[0020] The total thickness of the polycarbonate resin laminate 10 for hot bending is preferably 3 mm or more, more preferably 5 mm or more, and even more preferably 8 mm or more. This allows for improved strength while maintaining good thermoformability. On the other hand, the thickness of the polycarbonate resin laminate 10 for hot bending is preferably 15 mm or less, more preferably 12 mm or less, and even more preferably 10 mm or less. This allows for improved thermoformability while maintaining good strength.

[0021] The hot bending process is intended to soften the base material layer 1 by heating the polycarbonate resin laminate 10 for hot bending process and then bend it into a desired shape by applying pressure. Only a part of the polycarbonate resin laminate 10 for hot bending process may be heated and bent, or the entire polycarbonate resin laminate 10 may be heated and bent. The processing conditions are set appropriately.

[0022] The total light transmittance of the polycarbonate resin laminate 10 for hot bending process can be set appropriately depending on the application, but from the viewpoint of allowing light in while suppressing excessive glare from direct sunlight, it is preferably 10% or more, more preferably 15% or more, and is preferably 90% or less, more preferably 80% or less. The total light transmittance can be measured in accordance with JIS K7361-1.

[0023] The polycarbonate resin laminate 10 for hot bending preferably has a heat shrinkage rate of 5% or less, more preferably 3% or less, measured according to the method specified in JIS K 6735. By setting the heat shrinkage rate at or below the upper limit, even when the polycarbonate resin laminate 10 for hot bending has a molded portion thermoformed into a curved shape, peeling between the layers of the polycarbonate resin laminate 10 for hot bending in the molded portion can be appropriately suppressed or prevented. As a result, the polycarbonate resin laminate 10 for hot bending can have excellent weather resistance. Furthermore, when the polycarbonate resin laminate 10 for hot bending is printed to form a printed surface, misalignment of the printed surface can be appropriately suppressed or prevented. The heat shrinkage rate refers to the maximum value among the heat shrinkage rates measured along the surface direction of the polycarbonate resin laminate 10 for hot bending.

[0024] Each layer will be described in detail below.

[0025] [Substrate layer 1] The substrate layer 1 is a layer that forms the base of the polycarbonate resin laminate 10 for hot bending. The substrate layer 1 contributes to maintaining good transparency and mechanical strength of the polycarbonate resin laminate 10 for hot bending. In this embodiment, weather-resistant layers 3 are provided on both sides of the substrate layer 1 so as to be in contact with each other. The weather-resistant layers 3 may cover the entire surface of the substrate layer 1, may cover a portion of the surface, or may cover the surface discontinuously.

[0026] The base layer 1 preferably has optical transparency (visible light transparency). The base layer 1 may be colorless, or may be colored in red, blue, yellow, or the like with a colorant described below, as long as the base layer 1 maintains optical transparency.

[0027] The thickness of the base layer 1 is preferably 3 mm or more, more preferably 5 mm or more, and even more preferably 8 mm or more. This allows for improved strength while maintaining good thermoformability. On the other hand, the thickness of the base layer 1 is preferably 15 mm or less, more preferably 12 mm or less, and even more preferably 10 mm or less. This allows for improved thermoformability while maintaining good strength.

[0028] The thickness of the substrate layer 1 is preferably 93.00 to 99.99% of the total thickness of the polycarbonate resin laminate 10 for hot bending processability, and more preferably 95.00 to 99.90%.

[0029] (Resin composition for base layer) The base layer 1 is a resin layer containing a polycarbonate resin, and is formed using a resin composition for a base layer. Polycarbonate resins are excellent in transparency and mechanical strength such as rigidity, and also have high heat resistance.

[0030] Various resins can be used as the polycarbonate resin, but aromatic polycarbonate resins are preferred. Aromatic polycarbonate resins are synthesized, for example, by an interfacial polycondensation reaction between bisphenol and phosgene, or a transesterification reaction between bisphenol and diphenyl carbonate. A bisphenol-type polycarbonate resin having a skeleton derived from bisphenol is preferably used as the main material. By using such a bisphenol-type polycarbonate resin, the base layer 1 exhibits even greater strength.

[0031] The base layer 1 may contain various additives such as resins other than polycarbonate resin, ultraviolet absorbers described below, colorants, antioxidants, fillers, plasticizers, light stabilizers, heat ray absorbers, and flame retardants, as long as the transparency and mechanical strength of the polycarbonate resin laminate 10 for hot bending are maintained. For example, when the base layer 1 is molded by extrusion molding, discoloration can be suppressed and the transparency of the polycarbonate resin laminate 10 for hot bending can be maintained by selecting an additive having heat resistance.

[0032] When the base layer 1 contains a resin other than the above-mentioned polycarbonate resin, the proportion of the resin other than the polycarbonate resin is preferably 1 mass % or less, more preferably 0.5 mass % or less, and even more preferably 0.1 mass % or less, relative to the total amount of resin in the base layer 1, and it is even more preferable that the base layer does not contain any resin other than the polycarbonate resin.

[0033] When the substrate layer 1 contains an ultraviolet absorber, the content of the ultraviolet absorber is preferably 1 mass % or less, more preferably 0.5 mass % or less, even more preferably 0.1 mass % or less, and even more preferably no ultraviolet absorber is contained, relative to the total amount of the substrate layer 1. By setting the content of the ultraviolet absorber in the substrate layer 1 to the above upper limit or less, the transparency and functionality of the substrate layer 1 can be easily maintained.

[0034] As the colorant, known dyes and pigments may be used. When the base layer 1 contains a colorant, the content of the colorant is preferably 1% by mass or less, more preferably 0.5% by mass or less, and even more preferably 0.1% by mass or less, based on the total amount of the base layer 1, and it is even more preferable that the base layer does not contain a colorant.

[0035] Examples of the dye include acid dyes, direct dyes, reactive dyes, and basic dyes, and one or more selected from these may be used in combination.

[0036] The pigment is not particularly limited, but examples thereof include phthalocyanine pigments such as phthalocyanine green and phthalocyanine blue; azo pigments such as fast yellow, disazo yellow, condensed azo yellow, benzimidazolone yellow, dinitroaniline orange, benzimidazolone orange, toluidine red, permanent carmine, permanent red, naphthol red, condensed azo red, benzimidazolone carmine, and benzimidazolone brown; anthraquinone pigments such as anthrapyrimidine yellow and anthraquinonyl red; copper pigments such as copper fluoride, ... organic pigments such as azomethine pigments such as azomethine yellow, quinophthalone pigments such as quinophthalone yellow, isoindoline pigments such as isoindoline yellow, nitroso pigments such as nickel dioxime yellow, perinone pigments such as perinone orange, quinacridone pigments such as quinacridone magenta, quinacridone maroon, quinacridone scarlet, and quinacridone red, perylene pigments such as perylene red and perylene maroon, pyrrolopyrrole pigments such as diketopyrrolopyrrole red, and dioxazine pigments such as dioxazine violet; Carbon pigments such as bomb black, lamp black, furnace black, ivory black, graphite, and fullerene, chromate pigments such as yellow lead and molybdate orange, sulfide pigments such as cadmium yellow, cadmium lithopone yellow, cadmium orange, cadmium lithopone orange, vermilion, cadmium red, cadmium lithopone red, sulfide, ochre, titanium yellow, titanium barium nickel yellow, red iron oxide, red lead, umber, brown iron oxide, zinc iron chrome brown, chrome oxide, cobalt green, cobalt chrome green, titanium Examples of pigments include oxide pigments such as cobalt green, cobalt blue, cerulean blue, cobalt aluminum chrome blue, iron black, manganese ferrite black, cobalt ferrite black, copper chrome black, and copper chrome manganese black; hydroxide pigments such as viridian; ferrocyanide pigments such as Prussian blue; silicate pigments such as ultramarine; phosphate pigments such as cobalt violet and mineral violet; and other inorganic pigments (for example, cadmium sulfide and cadmium selenide). These pigments may be used alone or in combination of two or more.

[0037] [Hard Coat Layer 2] The hard coat layer 2 is provided on the substrate layer 1 and has the function of protecting the substrate layer 1. In this embodiment, weather-resistant layers 3 are provided on the upper and lower surfaces of the substrate layer 1, and the hard coat layer 2 is provided on the surface of the weather-resistant layer 3 opposite to the substrate layer 1.

[0038] The thickness of the hard coat layer 2 is preferably 1 μm or more, more preferably 3 μm or more, and even more preferably 5 μm or more. This improves the strength of the protective layer and suppresses breakage and cracking. On the other hand, the thickness of the hard coat layer 2 is preferably 20 μm or less, more preferably 15 μm or less, and even more preferably 10 μm or less. This makes it easier to maintain good thermal processability and light transmittance.

[0039] (Resin composition for hard coat layer) The hard coat layer 2 is formed using a resin composition for hard coat layer. The resin composition for hard coat layer is preferably one containing at least one of a silicon-modified (meth)acrylic resin and dispersible silica particles having a polymerizable group, and more preferably one containing both from the viewpoint of improving abrasion resistance.

[0040] (Silicon-modified (meth)acrylic resin) A silicone-modified (meth)acrylic resin (siloxane-modified (meth)acrylate) is a polymer (prepolymer) having a main chain in which structural units derived from a (meth)acrylic monomer having a (meth)acryloyl group are repeated, and a repeating body (side chain) in which structural units having a siloxane bond are repeated and linked to this main chain.

[0041] That is, it is a polymer (prepolymer) in which a (meth)acrylic compound as the main chain and a compound having a siloxane bond (—Si—O—Si—) as the side chain are linked together.

[0042] The silicon-modified (meth)acrylic resin, by virtue of having the aforementioned main chain, imparts excellent transparency to the hard coat layer 2, and by virtue of having a repeating body in which the structural unit having the aforementioned siloxane bond is repeated, imparts excellent scratch resistance and weather resistance to the hard coat layer 2, i.e., can impart the hard coat layer 2 with the function of a protective layer.

[0043] Specific examples of the main chain of the silicon-modified (meth)acrylic resin include those composed of repeating structural units derived from a monomer having a (meth)acryloyl group of at least one of the following formulas (1) and (2), and examples of those having repeating structural units derived from both of these monomers include those having the chemical formula shown in the following formula (12).

[0044] (In formula (1), n ​​represents an integer of 1 or more, R1 independently represents a hydrocarbon group, an organic group, or a hydrogen atom, and R0 independently represents a hydrocarbon group or a hydrogen atom.)

[0045] (In formula (2), m represents an integer of 1 or more, R2 independently represents a hydrocarbon group, an organic group, or a hydrogen atom, and R0 independently represents a hydrocarbon group or a hydrogen atom.)

[0046] (In formula (12), m and n represent integers of 1 or more, R1, R2, and R3 each independently represent a hydrocarbon group, an organic group, or a hydrogen atom, and R0 independently represent a hydrocarbon group or a hydrogen atom.)

[0047] Furthermore, at least one end of the main chain or side chain of such a structure is bonded to a repeating unit (sub-chain) in which a structural unit having a siloxane bond is repeated.

[0048] Because siloxane bonds have a high bonding strength, a silicon-modified (meth)acrylic resin having a repeating structure of structural units having siloxane bonds can provide a hard coat layer 2 with better heat resistance and weather resistance. Furthermore, the high bonding strength of siloxane bonds allows a hard hard coat layer 2 to be obtained, further improving the abrasion resistance and abrasion resistance of the polycarbonate resin laminate 10 for hot bending processability against impacts such as sand, dust, and flying stones. The effect of siloxane bonds can also be achieved by using silica particles, which will be described later. Furthermore, the effect can be made even more pronounced by using a silicon-modified (meth)acrylic resin and dispersible silica particles in combination.

[0049] Specific examples of repeating units in which structural units having siloxane bonds are repeated include those composed of repeating structural units having siloxane bonds of at least one of the following formulas (3) and (4):

[0050] (In formula (3), X1 represents a hydrocarbon group or a hydroxyl group.)

[0051] (In formula (4), X2 represents a hydrocarbon group or a hydroxyl group, and X3 represents a divalent group in which hydrogen has been removed from the hydrocarbon group or the hydroxyl group.)

[0052] Specific examples of the repeating structure in which the structural unit having a siloxane bond is repeated include those having polyorganosiloxane and those having silsesquioxane. The structure of the silsesquioxane may be any structure, such as a random structure, a cage structure, or a ladder structure.

[0053] Examples of the hydrocarbon group include alkyl groups such as a methyl group, an ethyl group, a propyl group, and an isopropyl group; cycloalkyl groups such as a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, and a cyclohexyl group; aryl groups such as a phenyl group, a naphthyl group, and a 2-methylphenyl group; aralkyl groups such as a benzyl group, a diphenylmethyl group, and a naphthylmethyl group; a phenyl group; and a biphenyl group.

[0054] In addition, it is preferable that unsaturated double bonds are introduced into the end or side chain of the repeating unit in which the structural unit having siloxane bond is repeated.Therefore, when the resin composition contains the urethane (meth)acrylate described later, it can bond with the (meth)acryloyl group of this urethane (meth)acrylate to form a network of silicon-modified (meth)acrylic resin and urethane (meth)acrylate.Therefore, in the hard coat layer 2, the silicon-modified (meth)acrylic resin and the urethane (meth)acrylate are more uniformly dispersed, and as a result, the hard coat layer 2 can more uniformly exhibit the above-mentioned properties throughout its entirety.

[0055] The content of the silicon-modified (meth)acrylic resin in the resin composition for the hard coat layer is not particularly limited, but is preferably 10 parts by mass or more and 70 parts by mass or less, and more preferably 20 parts by mass or more and 50 parts by mass or less, per 100 parts by mass of the resin composition for the hard coat layer. By setting the content of the silicon-modified (meth)acrylic resin to be equal to or more than the above-mentioned lower limit, the hardness of the hard coat layer 2 can be well maintained. On the other hand, by setting the content of the silicon-modified (meth)acrylic resin to be equal to or less than the above-mentioned upper limit, the flexibility of the hard coat layer 2 can be easily maintained.

[0056] Examples of the silicon-modified (meth)acrylic resin having the above-described structure include compounds represented by the following formulas (5) and (6).

[0057] (In formula (5), Me represents a methyl group, and m, n, and p each represent an integer of 1 or more.)

[0058] (In formula (6), Me represents a methyl group, m, n, and p each represent an integer of 1 or more, and R1, R2, R3, and R4 each independently represent a hydrocarbon group, an organic group, or a hydrogen atom.)

[0059] (Silica Particles) The silica particles are dispersible silica particles having a polymerizable group.

[0060] The silica particles are preferably a solvent dispersion sol. In the solvent dispersion sol of silica particles, the dispersion medium is preferably an organic solvent from the viewpoint of compatibility with other components and dispersibility. The organic solvent is not particularly limited, but examples thereof include ketone solvents, aromatic solvents, alcohol solvents, glycol solvents, glycol ether solvents, ester solvents, petroleum solvents, haloalkane solvents, amide solvents, etc. These may be used alone or in combination of two or more.

[0061] The silica particles may be surface-modified with an organic group or may not be surface-modified, but silica particles modified with an organic group having an unsaturated group on the surface are preferred. That is, it is preferable to obtain silica particles in the form of a composite in which an organic group having an unsaturated group on the surface is physically or chemically (preferably chemically) introduced onto the silica particle surface. The unsaturated group is preferably a radically polymerizable group, specifically a functional group having a carbon-carbon double bond (also referred to as a polymerizable double bond), such as a vinyl group, a (meth)acryloyl group, a (meth)acrylamide group, a vinyl ether group, or an allyl group. Of these, a (meth)acryloyl group is preferred from the viewpoints of adhesion and scratch resistance.

[0062] The silica particles may have any shape, such as spherical, hollow, porous, rod-like, plate-like, fibrous, or irregular shape, but the preferred shape is spherical.

[0063] The upper and lower limits of the particle size of the silica particles are preferably 5 to 200 nm, more preferably 10 to 100 nm.

[0064] The content of silica particles in the resin composition for hard coat layer is not particularly limited, but is preferably 10 parts by mass or more and 70 parts by mass or less, and more preferably 20 parts by mass or more and 50 parts by mass or less, per 100 parts by mass of the resin composition for hard coat layer. By setting the content of silica particles to the above lower limit or more, the hardness of the hard coat layer 2 can be well maintained and wear resistance can be obtained. On the other hand, by setting the content of silica particles to the above upper limit or less, the flexibility of the hard coat layer 2 can be easily maintained.

[0065] Furthermore, the resin composition for the hard coat layer may contain the following urethane (meth)acrylate, (meth)acrylate monomer, etc.

[0066] (Urethane (meth)acrylate) Preferably, the resin composition for a hard coat layer further contains urethane (meth)acrylate.

[0067] When an unsaturated double bond is introduced into the end or side chain of the repeating unit having a siloxane bond, which is included in the silicon-modified (meth)acrylic resin or silica particles, the resin composition for hard coat layer contains urethane (meth)acrylate, and the (meth)acryloyl group and the unsaturated double bond of this urethane (meth)acrylate are bonded to form a network of silicon-modified (meth)acrylic resin or silica particles and urethane (meth)acrylate.As a result, the resin composition for hard coat layer is cured to obtain a cured product, and a hard coat layer 2 composed of this cured product is formed.In addition, the curing of the resin composition for hard coat layer by the bonding of this (meth)acryloyl group and the unsaturated double bond is carried out by photocuring, which is curing by irradiating the resin composition for hard coat layer with energy rays such as ultraviolet light.

[0068] By containing urethane (meth)acrylate in the hard coat layer 2 formed as described above, the flexibility of the hard coat layer 2 can be improved, and since the polycarbonate resin laminate 10 for hot bending is applied to a part or all of the polycarbonate resin laminate 10 for hot bending processing having a curved shape, the occurrence of cracks on the surface of the hard coat layer 2 can be appropriately suppressed when the polycarbonate resin laminate 10 for hot bending processing is hot bent, and therefore excellent thermoformability can be imparted to the polycarbonate resin laminate 10 for hot bending processing.

[0069] Furthermore, by combining the above-mentioned silicon-modified (meth)acrylic resin with this urethane (meth)acrylate, it is possible to obtain a polycarbonate resin laminate 10 for hot bending that has both excellent scratch resistance and thermoformability at a high level. Furthermore, the improved scratch resistance makes it possible to effectively prevent scratches on the surface of the hard coat layer 2, even if sand, dust, flying stones, or the like collide with the hard coat layer 2 after irradiation with ultraviolet rays contained in sunlight by using the polycarbonate resin laminate 10 for hot bending.

[0070] The urethane (meth)acrylate is a compound having a main chain with a urethane bond (—OCONH—) and a (meth)acryloyl group linked to the main chain. The urethane (meth)acrylate is a monomer or oligomer.

[0071] The urethane (meth)acrylate having such a configuration is a compound with excellent flexibility due to the presence of a urethane bond. Therefore, by including the urethane (meth)acrylate in the hard coat layer 2, further flexibility (softness) can be imparted to the hard coat layer 2. Therefore, when the polycarbonate resin laminate 10 for hot bending processability is molded into a curved shape, the occurrence of cracks in the bent portion can be appropriately suppressed.

[0072] The urethane (meth)acrylate can be obtained, for example, as a reaction product between an isocyanate compound obtained by reacting a polyol with a diisocyanate, and a (meth)acrylate monomer having a hydroxyl group.

[0073] Examples of the polyol include polyether polyol, polyester polyol, and polycarbonate diol.

[0074] Polyester polyols can be obtained, for example, by polycondensation of a diol with a dicarboxylic acid or dicarboxylic acid chloride, or by esterifying a diol or dicarboxylic acid and then transesterifying it. Examples of dicarboxylic acids include adipic acid, succinic acid, glutaric acid, pimelic acid, sebacic acid, azelaic acid, maleic acid, terephthalic acid, isophthalic acid, and phthalic acid. Examples of diols include ethylene glycol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, dipropylene glycol, triethylene glycol, tetraethylene glycol, tripropylene glycol, and tetrapropylene glycol.

[0075] Furthermore, examples of polycarbonate diols that can be used include 1,4-butanediol, 1,6-hexanediol, ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, dipropylene glycol, 2-ethyl-1,3-hexanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,4-cyclohexanediol, and polyoxyethylene glycol, and these can be used alone or in combination of two or more.

[0076] Examples of (meth)acrylate monomers having a hydroxyl group include trimethylolpropane triacrylate, pentaerythritol triacrylate, dipentaerythritol triacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxybutyl acrylate, 3-hydroxybutyl acrylate, and polyethylene glycol monoacrylate.

[0077] The content of urethane (meth)acrylate in the resin composition for the hard coat layer is not particularly limited, but is preferably 10 parts by mass or more and 75 parts by mass or less, and more preferably 15 parts by mass or more and 65 parts by mass or less, per 100 parts by mass of the resin composition for the hard coat layer. If the content of urethane (meth)acrylate in the resin composition for the hard coat layer is less than the lower limit, the flexibility of the hard coat layer 2 may be poor, depending on the type of urethane (meth)acrylate. If the content of urethane (meth)acrylate in the resin composition for the hard coat layer exceeds the upper limit, the content of materials other than urethane (meth)acrylate in the resin composition for the hard coat layer may be relatively reduced, depending on the type of urethane (meth)acrylate, and the scratch resistance of the polycarbonate resin laminate 10 for hot bending process may be reduced.

[0078] ((Meth)acrylate Monomer) Preferably, the resin composition for a hard coat layer further contains a (meth)acrylate monomer.

[0079] When an unsaturated double bond is introduced into the end or side chain of a repeating unit of a structural unit having a siloxane bond, which is contained in the silicon-modified (meth)acrylic resin, the resin composition for the hard coat layer contains a (meth)acrylate monomer, and the (meth)acryloyl group of the (meth)acrylate monomer bonds with the unsaturated double bond, forming a network of the silicon-modified (meth)acrylic resin and the (meth)acrylate monomer, and as a result, the resin composition for the hard coat layer hardens to form the hard coat layer 2.

[0080] The (meth)acrylate monomer is not particularly limited, but examples thereof include pentaerythritol tetraacrylate, ditrimethylolpropane triacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, dipentaerythritol triacrylate, ethoxylated trimethylolpropane triacrylate, ethoxylated pentaerythritol triacrylate, ethoxylated pentaerythritol tetraacrylate, polyethylene glycol diacrylate, ethoxylated bisphenol A diacrylate, ethoxylated hydrogenated bisphenol A diacrylate, ethoxylated cyclohexane dimethanol diacrylate, tricyclodecane dimethanol diacrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxybutyl acrylate, 3-hydroxybutyl acrylate, and isobornyl acrylate, and one or more of these may be used in combination. Among these, from the viewpoint of improving the weather resistance of the polycarbonate resin laminate 10 for hot bending processability, a resin that does not contain aromatic groups is preferred.

[0081] The content of the (meth)acrylate monomer in the resin composition for the hard coat layer is not particularly limited, but is preferably 5 parts by mass or more and 55 parts by mass or less, and more preferably 10 parts by mass or more and 30 parts by mass or less, relative to 100 parts by mass of the resin composition for the hard coat layer.

[0082] (Isocyanate) Preferably, the resin composition for a hard coat layer further contains an isocyanate, which has an isocyanurate skeleton and di- or tri-functional isocyanate groups.

[0083] Thus, in the resin composition for hard coat layer, isocyanate functions as a cross-linking agent that bonds (cross-links) between molecules of the silicon-modified (meth)acrylic resin. That is, by including isocyanate as a cross-linking agent, the hydroxyl group of the main chain of the silicon-modified (meth)acrylic resin, which is a repeating structural unit derived from a (meth)acrylic monomer having a (meth)acryloyl group, reacts with the isocyanate group of the isocyanate to form a cross-linked structure composed of urethane bonds, and as a result, a hard coat layer 2 is formed that is composed of a cured product of the resin composition for hard coat layer. Note that the hard coat layer resin composition is cured by bonding this hydroxyl group with the isocyanate group by heat curing, which cures the resin composition for hard coat layer.

[0084] In the hard coat layer 2 formed as described above, a network can be constructed by bonding hydroxyl groups and isocyanate groups, so that the scratch resistance and weather resistance of the hard coat layer 2 can be further improved.

[0085] The content of the isocyanate in the resin composition for the hard coat layer is not particularly limited, but is preferably 3 parts by mass or more and 40 parts by mass or less, and more preferably 10 parts by mass or more and 25 parts by mass or less, relative to 100 parts by mass of the resin composition for the hard coat layer.

[0086] (Other Materials) The resin composition for hard coat layer may contain other materials in addition to the various materials described above. For example, resin materials other than the silicon-modified (meth)acrylic resin, photopolymerization initiators, ultraviolet absorbers described below, colorants, sensitizers, stabilizers, surfactants, antioxidants, reduction inhibitors, antistatic agents, surface conditioners, hydrophilic additives, fillers, and solvents can be mentioned, and one or more of these can be used in combination.

[0087] When the hard coat layer 2 contains an ultraviolet absorber, it is preferable that the ultraviolet absorber be a different type from the ultraviolet absorber contained in the weather-resistant layer 3 described below. For example, the ultraviolet absorber may be selected depending on the manufacturing method of the hard coat layer 2 and the weather-resistant layer 3, respectively. When the weather-resistant layer 3 is extrusion-molded, an ultraviolet absorber with relatively high heat resistance may be selected, and when the hard coat layer 2 is formed by coating, an ultraviolet absorber that is less likely to bleed during the coating film formation process and has relatively high dispersibility may be selected. Specifically, for example, it is preferable that the hard coat layer 2 contains a triazine-based compound having a reactive functional group (such as "RUVA-93" manufactured by Otsuka Chemical Co., Ltd. or "Tinuvin 400" manufactured by BASF Japan Ltd.) and the weather-resistant layer 3 contains a triazine-based compound with excellent heat resistance that can exhibit its function even after the extrusion process (such as "Tinuvin 1577" manufactured by BASF Japan Ltd.). This allows the hard coat layer 2 and the weather-resistant layer 3 to be appropriately formed, resulting in increased adhesion between them and improving the mechanical strength and weather resistance of the polycarbonate resin laminate for hot bending process 10. Furthermore, by using ultraviolet absorbers with different absorption wavelength ranges, the absorbable wavelength range is broadened, making it easier to obtain stable weather resistance.

[0088] The content of the ultraviolet absorber in the hard coat layer 2 is preferably 1% by mass or more and 6% by mass or less, more preferably 2% by mass or more and 5.5% by mass or less, and even more preferably 3% by mass or more and 6% by mass or less, relative to the total amount of the hard coat layer 2. By setting the content of the ultraviolet absorber in the hard coat layer 2 to the above-mentioned lower limit or more, better weather resistance can be obtained. On the other hand, by setting the content of the ultraviolet absorber in the hard coat layer 2 to the above-mentioned upper limit or less, good transparency and hot bending processability can be easily obtained while maintaining weather resistance.

[0089] [Weather-resistant layer 3] The weather-resistant layer 3 is interposed between the substrate layer 1 and the hard coat layer 2, and has the function of protecting the substrate layer 1 from ultraviolet rays. In the polycarbonate resin laminate 10 for hot bending process, the weather-resistant layers 3 are provided on the upper and lower surfaces of the substrate layer 1, respectively.

[0090] The weather-resistant layer 3 preferably has light transmittance (visible light transmittance).

[0091] The thickness of the weather-resistant layer 3 is preferably 10 μm or more, more preferably 20 μm or more, and even more preferably 30 μm or more. This improves the strength of the protective layer and suppresses breakage and cracking. On the other hand, the thickness of the weather-resistant layer 3 is preferably 100 μm or less, more preferably 90 μm or less, and even more preferably 80 μm or less. This makes it easier to maintain good thermal processability and light transmittance.

[0092] The thickness of the weather-resistant layer 3 is preferably 0.06 to 3.5%, more preferably 0.08 to 2.0%, and even more preferably 0.1 to 1.5%, of the entire thickness of the polycarbonate resin laminate for hot bending 10. By setting the thickness within this range, good hot bending processability can be obtained while improving weather resistance.

[0093] (Resin Composition for Weather-Resistant Layer) The weather-resistant layer 3 is a resin layer containing an ultraviolet absorber. Resin materials include, but are not limited to, acrylic resins, polycarbonates, polystyrenes, epoxy resins, cyclic ether resins such as oxetane resins, polyamides, polyimides, polybenzoxazoles, polysilanes, polysilazanes, silicone resins, fluororesins, polyurethanes, polyolefins, polybutadiene, polyisoprene, polychloroprene, polyesters such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT), polyethylene succinate, polysulfones, polyethers, and cyclic olefin resins such as benzocyclobutene resins and norbornene resins. One or more of these may be used in combination (as a polymer alloy, polymer blend (mixture), copolymer, etc.). Among these, polycarbonates or polyamides are preferred, and polycarbonates are more preferred. The use of polycarbonate can improve the strength and transparency of the polycarbonate resin laminate for hot bending process 10. Furthermore, it is preferable that the weather-resistant layer 3 does not contain silicone-modified polycarbonate.

[0094] The content of the ultraviolet absorber in the weather-resistant layer 3 is preferably 1% by mass or more and 10% by mass or less, more preferably 2% by mass or more and 8% by mass or less, and even more preferably 3% by mass or more and 6% by mass or less, relative to the total amount of the weather-resistant layer 3. By setting the content of the ultraviolet absorber in the weather-resistant layer 3 to the above-mentioned lower limit or more, better weather resistance can be obtained. On the other hand, by setting the content of the ultraviolet absorber in the weather-resistant layer 3 to the above-mentioned upper limit or less, it becomes easier to obtain good transparency and hot bending processability while maintaining weather resistance.

[0095] (Ultraviolet absorber) The ultraviolet absorber is not particularly limited, but examples thereof include compounds that absorb light having a wavelength of 100 nm or more and 400 nm or less. This can suppress the transmission of ultraviolet light and visible light having a relatively short wavelength (light having a wavelength of 400 nm or less), thereby improving weather resistance.

[0096] The ultraviolet absorber is not particularly limited, but examples thereof include triazine-based, benzophenone-based, benzotriazole-based, and cyanoacrylate-based compounds, and one or two of these may be used in combination. Among these, triazine-based compounds are preferred.

[0097] Examples of triazine compounds include 2-mono(hydroxyphenyl)-1,3,5-triazine compounds, 2,4-bis(hydroxyphenyl)-1,3,5-triazine compounds, and 2,4,6-tris(hydroxyphenyl)-1,3,5-triazine compounds. Specific examples include 2,4-diphenyl-6-(2-hydroxy-4-methoxyphenyl)-1,3,5-triazine, 2,4-diphenyl-6-(2-hydroxy-4-ethoxyphenyl)-1,3,5-triazine, and 2,4-diphenyl-(2-hydroxy-4-propoxyphenyl)-1,3,5-triazine. )-1,3,5-triazine, 2,4-diphenyl-(2-hydroxy-4-butoxyphenyl)-1,3,5-triazine, 2,4-diphenyl-6-(2-hydroxy-4-butoxyphenyl)-1,3,5-triazine, 2,4-diphenyl-6-(2-hydroxy-4-hexyloxyphenyl)-1,3,5-triazine, 2,4-diphenyl-6-(2-hydroxy-4-octyloxyphenyl)-1,3,5-triazine, 2,4-diphenyl-6-(2-hydroxy-4-dodecyloxyphenyl)-1,3,5-triazine, 2,4- Diphenyl-6-(2-hydroxy-4-benzyloxyphenyl)-1,3,5-triazine, 2,4-diphenyl-6-(2-hydroxy-4-butoxyethoxy)-1,3,5-triazine, 2,4-bis(2-hydroxy-4-butoxyphenyl)-6-(2,4-dibutoxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-4-methoxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-4-ethoxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-4 -propoxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-4-butoxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-4-hexyloxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-4-octyloxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-4-dodecyloxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-4-benzyloxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-4-ethoxyethoxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-4-butoxyethoxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-4-propoxyethoxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-4-methoxycarbonylpropyloxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-4-ethoxycarbonylethyloxyphenyl)-1,3,5-triazine, 2,4,6- Tris(2-hydroxy-4-(1-(2-ethoxyhexyloxy)-1-oxopropan-2-yloxy)phenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-3-methyl-4-methoxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-3-methyl-4-ethoxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-3-methyl-4-propoxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-3-methyl-4-butoxyphenyl) -1,3,5-triazine, 2,4,6-tris(2-hydroxy-3-methyl-4-hexyloxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-3-methyl-4-octyloxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-3-methyl-4-dodecyloxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-3-methyl-4-benzyloxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-3-methyl-4-ethoxyphenyl)-1,3,5-triazine 2,4,6-tris(2-hydroxy-3-methyl-4-butoxyethoxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-3-methyl-4-propoxyethoxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-3-methyl-4-methoxycarbonylpropyloxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-3-methyl-4-ethoxycarbonylethyloxyphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-3-methyl-4-(1-(2-ethoxyhexyloxy)-1-oxopropan-2-yloxy)phenyl)-1,3,5-triazine. Commercially available triazine-based ultraviolet absorbers include, for example, "Tinuvin 1577," "Tinuvin 400," and "Tinuvin 405" (manufactured by BASF Japan Ltd.), and "RUVA-93" (manufactured by Otsuka Chemical Co., Ltd.), and these may be used alone or in combination of two or more.

[0098] Among these, the ultraviolet absorber contained in the weather-resistant layer 3 is preferably a triazine-based compound.

[0099] [Transition Layer] A transition layer (not shown) may be provided between the hard coat layer 2 and the weather-resistant layer 3. The transition layer contains at least some of the components of the hard coat layer 2 and at least some of the components of the weather-resistant layer 3. This increases the adhesion between the hard coat layer 2 and the weather-resistant layer 3, and improves the heat bending processability of the polycarbonate resin laminate 10 for heat bending processability.

[0100] The thickness of the transition layer is preferably 2 to 9 μm, more preferably 3 to 5 μm.

[0101] The transition layer can be confirmed by observation with a scanning electron microscope (SEM). That is, another layer (transition layer) having a different brightness can be confirmed between the hard coat layer 2 and the weather-resistant layer 3.

[0102] (Method of Producing the Transition Layer) The transition layer can be formed by applying a resin composition for a hard coat layer onto the weather-resistant layer 3 to form the hard coat layer 2. That is, by forming the weather-resistant layer 3 and then forming the hard coat layer 2 by applying the resin composition for a hard coat layer, the solvent contained in the resin composition for a hard coat layer can cause a portion of the surface of the weather-resistant layer 3 to be transferred to the subsequent hard coat layer 2. This can improve the adhesion between the hard coat layer 2 and the weather-resistant layer 3 and improve thermal processability such as bending.

[0103] [Others] The polycarbonate resin laminate 10 for hot bending may further have other layers laminated on the hard coat layer 2, as necessary. Examples of other layers include a decorative layer. This can enhance the design of the polycarbonate resin laminate 10 for hot bending. In order to obtain good hot bending processability and transparency in the polycarbonate resin laminate 10 for hot bending, it is preferable not to provide an adhesive layer between the substrate layer 1, the weather-resistant layer 3, and the hard coat layer 2.

[0104] [Uses] The polycarbonate resin laminate 10 for heat bending process can also be used by being attached to curved window members found in vehicles such as automobiles, motorcycles, and trains, as well as in aircraft, ships, houses, etc. This window member can be applied to window members provided in vehicles and the like that are positioned between a person and an object that the person views, and can also be applied to window members that are positioned between various devices, such as sensors and display devices, provided in vehicles and the like, and an object.

[0105] <Method for manufacturing polycarbonate resin laminate 10 for hot bending process> The method for manufacturing polycarbonate resin laminate 10 for hot bending process includes the following steps: (Step 1) A step of co-extrusion molding a resin composition for a base layer and a resin composition for a weather-resistant layer to laminate a base layer 1 and a weather-resistant layer 3. (Step 2) A step of applying a resin composition for a hard coat layer to the surface of the laminated weather-resistant layer 3 opposite to the base layer 1, thereby forming a hard coat layer 2 on the base layer 1. Each step will be described in detail below.

[0106] (Step 1) First, a resin composition for the base layer and a resin composition for the weather-resistant layer are prepared, respectively. For example, the resin composition for the base layer can be prepared by premixing a polycarbonate resin raw material and any additives using a mixer, followed by extrusion melt kneading, granulation using a granulator, and pelletization. Similarly, for the resin composition for the weather-resistant layer, the constituent resin raw materials and any additives can be premixed using a mixer, followed by extrusion melt kneading, granulation using a granulator, and pelletization. Next, the pelletized materials are co-extruded using a known extruder to form sheets, and then laminated to form the base layer 1 and the weather-resistant layer 3. Furthermore, when laminating by co-extrusion, it is also possible to directly melt-knead the materials in an extruder and extrude them through a die to form sheets, thereby laminating them.

[0107] In the coextrusion method, each resin is melt-extruded using a separate extruder, and the resins are laminated into a sheet using a feed block or multi-manifold die. The laminated sheet may be cooled before being wound onto a roll.

[0108] (Step 2) Next, a hard coat layer resin composition is applied to the surface of the laminated weather-resistant layer 3 opposite the substrate layer 1. The application method is not particularly limited, and examples include known and commonly used application methods such as brush coating, roller coating, spray coating, dip coating, flow coater coating, roll coater coating, and electrodeposition coating. The hard coat layer resin composition is prepared as a varnish-like liquid material containing a solvent. After applying the varnish-like hard coat layer resin composition to the weather-resistant layer 3, the solvent is dried and the composition is cured, thereby forming the hard coat layer 2 on the weather-resistant layer 3. Specifically, when the hard coat layer resin composition contains an ultraviolet absorber, the liquid coating of the hard coat layer resin composition can be cured by irradiating it with ultraviolet light at a high exposure dose (e.g., 1000 mJ to 2000 mJ).

[0109] By going through the above steps, the polycarbonate resin laminate 10 for hot bending process can be manufactured.

[0110] <Curved Member> The curved member of this embodiment is obtained by heat bending the polycarbonate resin laminate for heat bending 10. The heat bending conditions are set appropriately, and examples include a heat bending method using partial heating with a pipe heater, a non-contact double-sided sandwich heater, a far-infrared heater, or the like, or total heating with an electric furnace.

[0111] Although the embodiments of the present invention have been described above with reference to the drawings, these are merely examples of the present invention, and various other configurations can also be adopted.

[0112] Next, the present invention will be described in detail with reference to examples, but the content of the present invention is not limited to the examples.

[0113] 1. Preparation of Raw Materials First, the raw materials used in the production of the polycarbonate resin laminate for hot bending process are shown below.

[0114] [Materials for the Base Layer and Weather-Resistant Layer] Polycarbonate Resin 1: Bisphenol A polycarbonate (Mitsubishi Engineering Plastics Corporation, "E2000FN") was prepared. Additive 1: Additive 1 was prepared by blending 99.7% by mass of polycarbonate resin, 0.1% by mass of carbon black, 0.1% by mass of 1,4-bis[(2,6-diethyl-4-methylphenyl)amino]-9,10-anthraquinone, 0.05% by mass of 3-methyl-6-[(4-methylphenyl)amino]-3H-dibenzo[f,ij]isoquinoline-2,7-dione, and 0.05% by mass of 1-phenylthioanthraquinone. Ultraviolet Absorber 1: Hydroxyphenyltriazine-based ultraviolet absorber (BASF Japan, "Tinuvin 1577 ED") was prepared.

[0115] [Hard Coat Layer Materials] Silicon-modified (meth)acrylic resin 1: A siloxane-modified acrylate (manufactured by DIC Corporation, "MFG Coat SD-101") was prepared. Silica particles 1: A BYK-UV3518 manufactured by BYK Japan was prepared. Urethane (meth)acrylate 1: A 7.8-functional urethane acrylate (manufactured by Mitsubishi Chemical Corporation, "UV-1700B") was prepared. Urethane (meth)acrylate 2: A bifunctional urethane acrylate (manufactured by Mitsubishi Chemical Corporation, "UV-3310B") was prepared. (Meth)acrylate monomer 1: A bifunctional acrylate monomer (manufactured by Shin-Nakamura Chemical Co., Ltd., "A-BPE-4") was prepared. Polymerization initiator 1: A photopolymerization initiator (manufactured by IGM Resins). Ultraviolet absorber 2: A hydroxyphenylbenzotriazole-based ultraviolet absorber having a (meth)acryloyl group (manufactured by Otsuka Chemical Co., Ltd., "RUVA-93") was prepared. Ultraviolet absorber 3: A hydroxyphenyltriazine-based ultraviolet absorber (manufactured by BASF Japan, Ltd., "Tinuvin 479") was prepared.

[0116] 2. Preparation of Resin Composition for Hard Coat Layer 60.0 mass% of urethane (meth)acrylate 1, 10.0 mass% of urethane (meth)acrylate 2, 20.0 mass% of (meth)acrylate monomer 1, 5.0 mass% of polymerization initiator 1, 2.5 mass% of ultraviolet absorber 2, and 2.5 mass% of ultraviolet absorber 3 were added, and the mixture was diluted with propylene glycol monomethyl ether (PM) as a solvent, followed by stirring to prepare coating material composition 1.

[0117] 3. Formation of polycarbonate resin laminate (sheet) for hot bending process Example 1 A resin composition for the base layer, consisting of 99.75% by mass of polycarbonate-based resin 1 and 0.25% of additive 1, and a resin composition for the weather-resistant layer, consisting of 95% by mass of polycarbonate-based resin 1 and 5% by mass of ultraviolet absorber 1, were co-extruded to form a laminate comprising the base layer and the weather-resistant layer. The laminate had a total thickness of 8 mm for the base layer and the weather-resistant layer, and the thickness of the weather-resistant layer was 50 μm.

[0118] The above-mentioned coating material composition 1 was used as a resin composition for a hard coat layer, and the resin composition for a hard coat layer was applied to the weather-resistant layer side of the obtained laminate, dried at 80°C, and UV-cured to form a hard coat layer with a thickness of 8 μm. This resulted in a polycarbonate resin laminate sheet for hot bending processing. The UV curing conditions were as follows: an electrodeless UV lamp manufactured by FUSION Systems, irradiation distance 50 mm, conveyor speed 1.5 m / min, irradiation intensity 500 mW / cm ２ , cumulative light intensity 1700 mJ / cm ２ UV light was irradiated under the following conditions.

[0119] Examples 2 to 6 Polycarbonate resin laminate sheets for hot bending process were obtained in the same manner as in Example 1, except that 1 coating material composition, 1 silicon-modified (meth)acrylic resin, and 1 silica particle were mixed in the proportions (parts by mass) shown in Table 1 to prepare a resin composition for a hard coat layer.

[0120] Comparative Example 1 In the same manner as in Example 1, a laminate comprising a substrate layer and a weather-resistant layer was formed by co-extrusion of a resin composition for a substrate layer composed of 99.75% by mass of polycarbonate-based resin 1 and 0.25% of additive 1, and a resin composition for a weather-resistant layer composed of 95% by mass of polycarbonate-based resin 1 and 5% by mass of ultraviolet absorber 1. No hard coat layer was provided, and the resulting laminate was used as a polycarbonate resin laminate sheet for hot bending process.

[0121] Comparative Examples 2 to 6 A substrate sheet was obtained by extrusion molding a resin composition for a substrate layer composed of 99.75% by mass of polycarbonate-based resin 1 for the substrate layer and 0.25% of additive 1. A resin composition for a hard coat layer was prepared in the same manner as in Example 1, except that the mixing ratios of coating material composition 1, silicon-modified (meth)acrylic resin 1, and silica particles 1 were as shown in Table 1, and the obtained resin composition for a hard coat layer was applied to the surface of a substrate sheet to form a hard coat layer in the same manner as in Example 1. This was used as a polycarbonate resin laminate sheet for hot bending process.

[0122] The obtained laminate was subjected to the following measurements and evaluations. The results are shown in Tables 1 and 2.

[0123] Observation of Transition Layer For each laminate, the presence of a transition layer between the weather-resistant layer and the hard coat layer was confirmed by SEM observation, and the thickness (μm) of the transition layer was measured.

[0124] ・L ＊ a ＊ b ＊ a in the color system ＊ value and b ＊ The appearance of each laminate was measured using a tristimulus value direct reading colorimeter (manufactured by Suga Test Instruments Co., Ltd., "Color Cute i") under a D65 light source with a 10° field of view and a transmission method. ＊ value, b ＊ The values ​​were measured.

[0125] Total Light Transmittance (%) The total light transmittance (%) of each laminate was determined using a haze meter (trade name: NDH2000, manufactured by Nippon Denshoku Kogyo Co., Ltd.) in accordance with JIS K7361-1 (1997).

[0126] Heat shrinkage (%): Test specimens (150 mm wide, 150 mm long, 8 mm thick) were prepared using each laminate. A circle with a diameter of 100 mm was drawn on the test specimen with a compass. The specimen was then heated and dried for 24 hours in a hot air circulating oven set at 90°C. After cooling to 23°C in a desiccator, the diameter L0 of the test specimen was measured in both the machine direction (the co-extrusion direction of the laminate; MD direction) and the direction perpendicular to the machine direction (TD direction). The test specimen was then heated for 75 minutes in a hot air circulating oven set at 190°C, cooled to 23°C in a desiccator, and the diameter L1 was measured at the same location as the diameter of the circle measured earlier. The obtained values ​​were applied to the following formula (A) to calculate the heat shrinkage (%): Heat shrinkage (%) = {(L0 - L1) / L0} × 100 (A)

[0127] Weather resistance Each laminate was subjected to an accelerated test using a carbon arc sunshine weatherometer in accordance with JIS K 5600, and the yellowing index (ΔYI) after 1000 hours was measured, and the appearance (color) was observed and evaluated according to the following criteria. Criteria ⊚: ΔYI was less than 0.6 and there was no change in appearance (color). ◯: ΔYI was less than 1.0 and there was no change in appearance (color). △: ΔYI was 1.0 or more and less than 2.0 and there was a slight change in appearance (color). ×: ΔYI was 2.0 or more and there was a change in appearance (color).

[0128] - Heat bending processability Test specimens (width 60 mm, length 120 mm) were prepared using each laminate. Next, the test specimens were heated for 10 minutes in a hot air circulating oven set at 170 ° C to soften them. Immediately after removing them from the oven, the test specimens were placed along the longitudinal direction of a wooden cylinder via a flannel cloth, with the hard coat layer side of the test specimen facing outward, and the test specimens were held in this state until the temperature of the test specimens cooled to near room temperature, and the test specimens were subjected to single-curve molding. The appearance of the test specimens was then observed and evaluated according to the following criteria. Wooden cylinders with radii of 150 mm and 200 mm were prepared, and single-curve molding was performed on each. - Criteria ⊚: Thermoforming was possible using both 150 mm and 200 mm radius wooden molds, and no cracks, coating peeling, or changes in appearance occurred. Good: With the 150 mm radius wooden mold, cracks and paint peeling occurred and changes in appearance were observed due to thermoforming, but with the 200 mm radius wooden mold, thermoforming was possible and no cracks, paint peeling occurred or changes in appearance occurred. Bad: With both the 150 mm and 200 mm radius wooden molds, cracks, paint peeling occurred and changes in appearance such as cloudiness and surface roughness occurred due to thermoforming.

[0129] Abrasion Resistance The surface of each laminate was subjected to a Taber abrasion test in accordance with ASTM D1044 using an abrasive wheel (product name: CS-10F, manufactured by Taber) under conditions of a load of 500 g and 500 revolutions. The cloudiness (haze value) of the surface of the laminate before and after the Taber abrasion test was measured, and the amount of change in haze value (ΔH; %) was calculated and evaluated according to the following criteria. The haze value was measured using a haze meter (product name: NDH2000, manufactured by Nippon Denshoku Industries Co., Ltd.). Criteria ◎: ΔH was less than 5%, and abrasion resistance was excellent. ○: ΔH was 5% or more but less than 10%, and abrasion resistance was good. ×: ΔH was 10% or more, and abrasion resistance was not good.

[0130]

[0131]

[0132] This application claims priority based on Japanese Patent Application No. 2024-012584, filed January 31, 2024, the disclosure of which is incorporated herein by reference in its entirety.

[0133] 10 Polycarbonate resin laminate for hot bending processing 1 Base layer 2 Hard coat layer 3 Weather-resistant layer

Claims

1. A polycarbonate resin laminate for hot bending processability, comprising: a substrate layer containing a polycarbonate resin; and a hard coat layer laminated together; wherein a weather-resistant layer is interposed between the substrate layer and the hard coat layer; and the weather-resistant layer contains a polycarbonate resin and an ultraviolet absorber.

2. A polycarbonate resin laminate for heat bending according to claim 1, wherein the content of the ultraviolet absorber contained in the weather-resistant layer is 1% by mass or more and 10% by mass or less relative to the total amount of the weather-resistant layer.

3. A polycarbonate resin laminate for heat bending according to claim 1 or 2, wherein the hard coat layer contains an ultraviolet absorber of a different type from the ultraviolet absorber contained in the weather-resistant layer.

4. A polycarbonate resin laminate for heat bending processing according to any one of claims 1 to 3, wherein the content of the ultraviolet absorber contained in the base layer is 1 mass % or less relative to the total amount of the base layer.

5. The polycarbonate resin laminate for heat bending according to any one of claims 1 to 4, wherein the L of the polycarbonate resin laminate for heat bending ＊ a ＊ b ＊ a in the color system ＊ Values are -6 to 1, b ＊ A polycarbonate resin laminate for hot bending process, having a value of -8 to 2.

5.

6. A polycarbonate resin laminate for use in hot bending according to any one of claims 1 to 5, wherein the thickness (μm) of the weather-resistant layer is 0.06 to 3.5% of the total thickness (μm) of the polycarbonate resin laminate for use in hot bending.

7. A polycarbonate resin laminate for use in hot bending according to any one of claims 1 to 6, wherein the thickness (μm) of the weather-resistant layer is 10 to 100 μm.

8. A polycarbonate resin laminate for use in heat bending according to any one of claims 1 to 7, wherein the ultraviolet absorber contained in the weather-resistant layer is a triazine-based ultraviolet absorber.

9. A polycarbonate resin laminate for use in hot bending according to any one of claims 1 to 8, wherein the base layer and the weather-resistant layer are laminated by co-extrusion molding.

10. A polycarbonate resin laminate for heat bending according to any one of claims 1 to 9, further comprising a transition layer between the hard coat layer and the weather-resistant layer, the transition layer containing at least a portion of the components of the hard coat layer and at least a portion of the components of the weather-resistant layer.

11. A polycarbonate resin laminate for use in hot bending according to any one of claims 1 to 10, wherein the thickness (μm) of the hard coat layer is 1 to 20 μm.

12. A polycarbonate resin laminate for hot bending processing according to any one of claims 1 to 11, wherein the thickness (μm) of the polycarbonate resin laminate for hot bending processing is 3 to 15 mm.

13. A curved member obtained by heat bending the polycarbonate resin laminate for heat bending process according to any one of claims 1 to 12.

14. A method for producing a polycarbonate resin laminate for use in hot bending, in which a substrate layer containing a polycarbonate resin, a weather-resistant layer, and a hard coat layer are laminated in this order, the method comprising: a step of co-extruding a resin composition for the substrate layer and a resin composition for the weather-resistant layer to laminate the substrate layer and the weather-resistant layer; and a step of applying a resin composition for the hard coat layer to the surface of the laminated weather-resistant layer opposite to the substrate layer, thereby forming a hard coat layer on the substrate layer, wherein the weather-resistant layer contains a polycarbonate resin and an ultraviolet absorber.

15. A method for producing a curved member, comprising the step of hot bending a polycarbonate resin laminate for hot bending process obtained by the method for producing a polycarbonate resin laminate for hot bending process according to claim 14 to form a curved member.

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