Multilayer object and dust-proof cover for head-up displays

Abstract

Provided are a multilayer object and a dust-proof cover for head-up displays in which the multilayer object is used. A multilayer object according to the present disclosure comprises (a) a (meth)acrylate-based hard coat layer, (b) a thermoplastic acrylic resin layer, (c) a polycarbonate resin layer, and (d) a (meth)acrylate-based hard coat layer in the stated order, wherein each of the (a) (meth)acrylate-based hard coat layer and the (d) (meth)acrylate-based hard coat layer independently contains 20-80 mass% of inorganic particles, and the thickness of the (b) thermoplastic acrylic resin layer is 15-80 μm.

Description

Multilayer and dust cover for head-up displays

[0001] The present invention relates to multilayer bodies and dust covers for head-up displays. In particular, it relates to multilayer bodies having a polycarbonate resin layer and an acrylic resin layer.

[0002] Polycarbonate resin is widely used in various fields because, in addition to its excellent transparency, it has superior processability and impact resistance compared to glass, and there is no concern about toxic gases compared to other plastic materials. It is also used as a material for thermoforming, such as vacuum forming and pressure forming.

[0003] On the other hand, polycarbonate resin generally has low surface hardness, making molded products made from polycarbonate resin prone to scratches. Therefore, when polycarbonate resin is made into a film, a layer containing acrylic resin or a hard coat layer (protective layer) is being considered to prevent scratches on the product surface. Such multilayer materials are described in Patent Documents 1 and 2.

[0004] International Publication No. 2016 / 060100, International Publication No. 2021 / 215435

[0005] In multilayer structures having a polycarbonate resin layer (polycarbonate resin layer) and an acrylic resin layer (acrylic resin layer), high surface hardness is required. Furthermore, depending on the application, flame retardancy may be required for the multilayer structure. The present invention aims to solve these problems and provides a multilayer structure with high surface hardness and excellent flame retardancy, and a dust cover for a head-up display using the same.

[0006] Based on the above problems, the inventors conducted research and found that the above problems can be solved by reducing the thickness of the acrylic resin layer and providing hard coat layers containing inorganic particles on both sides of the multilayer. Specifically, the above problems were solved by the following means: [1] A multilayer having (a) a (meth)acrylate hard coat layer, (b) a thermoplastic acrylic resin layer, (c) a polycarbonate resin layer, and (d) a (meth)acrylate hard coat layer in this order, wherein the (a) (meth)acrylate hard coat layer and the (d) (meth)acrylate hard coat layer each independently contain inorganic particles in a proportion of 20 to 80% by mass, and the thickness of the (b) thermoplastic acrylic resin layer is 15 to 80 μm. [2] Particle size (D ５０ [1] The multilayer according to [1], wherein the average of the (a) (meth)acrylate hard coat layer is less than 120 nm. [3] The multilayer according to [1] or [2], wherein the pencil hardness of the multilayer according to [1] or [2] is H or higher when measured from the (a) (meth)acrylate hard coat layer side under a 500 g load. [4] The multilayer according to any one of [1] to [3], wherein the (d) (meth)acrylate hard coat layer contains a component derived from polyfunctional urethane (meth)acrylate. [5] The multilayer according to any one of [1] to [4], wherein the content of the flame retardant in the (c) polycarbonate resin layer is less than 0.01% by mass. [6] The multilayer according to any one of [1] to [4], wherein the content of the flame retardant in the (c) polycarbonate resin layer is 0.01% by mass or more and less than 0.1% by mass. [7] The multilayer according to any one of [1] to [6], further comprising an anti-reflective layer. [8] The multilayer according to any one of [1] to [7], further comprising a polarizing layer. A dust cover for a head-up display, including a multilayer structure as described in any one of [9], [1], to [8].

[0007] This invention makes it possible to provide a multilayer material with high surface hardness and excellent flame retardancy, and a dust cover for a head-up display using the same.

[0008] Figure 1 is a schematic diagram showing the layer structure of the multilayer body of the present invention.

[0009] Hereinafter, embodiments for carrying out the present invention (hereinafter simply referred to as "this embodiment") will be described in detail. Note that the following embodiments are illustrative examples for explaining the present invention, and the present invention is not limited to these embodiments. In this specification, "~" is used to mean that the numerical values ​​before and after it include the lower and upper limits. "A~B" means A or greater and B or less. Furthermore, the upper and lower limits of numerical values ​​in this specification are given as examples of this embodiment, regardless of the combination of the upper and lower limits. In this specification, various physical properties and characteristic values ​​are given at 23°C unless otherwise specified.

[0010] In this specification, "(meth)acrylate" refers to both acrylate and methacrylate, or either of them; "(meth)acrylic" refers to both acrylic and methacrylic, or either of them; and "(meth)acryloyl" refers to both acryloyl and methacryloyl, or either of them.

[0011] In this specification, weight-average molecular weight and number-average molecular weight are polystyrene equivalent values ​​measured by GPC (gel permeation chromatography) unless otherwise specified. In this specification, "film" and "multilayer" refer to molded articles that are thin in thickness relative to their length and width, and are generally flat. The term "film" includes sheets. In this specification, "film" may be single-layer or multilayer. If the measurement methods etc. described in the standards shown in this specification differ from year to year, unless otherwise specified, the standards as of January 1, 2024 shall apply. If the measurement methods etc. described in the standards shown in this specification have been abolished as of January 1, 2024, the standards at the time of abolition shall apply. Figure 1 may not be consistent with reality in terms of scale, etc.

[0012] The multilayer body of this embodiment is a multilayer body having (a) a (meth)acrylate-based hard coat layer, (b) a thermoplastic acrylic resin layer, (c) a polycarbonate resin layer, and (d) a (meth)acrylate-based hard coat layer in this order, characterized in that the (a) (meth)acrylate-based hard coat layer and the (d) (meth)acrylate-based hard coat layer each independently contain inorganic particles in a proportion of 20 to 80% by mass, and the thickness of the (b) thermoplastic acrylic resin layer is 15 to 80 μm. By adopting such a configuration, it is possible to provide a multilayer body with high surface hardness and excellent flame retardancy.

[0013] (b) The thermoplastic acrylic resin layer is inherently more flammable than the (c) polycarbonate resin layer. In this embodiment, the multilayer structure is made relatively less flammable by making the (b) thermoplastic acrylic resin layer thinner. On the other hand, if a hard coat layer is provided on the surface of the (c) polycarbonate resin layer to increase the surface hardness of the multilayer structure, the flammable components increase, and it usually becomes more flammable. In this embodiment, the multilayer structure was made less flammable by providing hard coat layers on both sides of the (b) thermoplastic acrylic resin layer and the (c) polycarbonate resin layer. In particular, it is highly valuable because flame retardancy can be achieved even if the (c) polycarbonate resin layer does not contain a flame retardant.

[0014] The embodiments of the present invention will be described in detail below, but the description of the constituent elements described below is an example of an embodiment of the present invention and is not limited to these. In this specification, when the term "hard coat layer" is used, it means both (a) (meth)acrylate-based hard coat layer and (d) (meth)acrylate-based hard coat layer. In this specification, the (b) thermoplastic acrylic resin layer and the (c) polycarbonate resin layer may be collectively referred to as the substrate. It goes without saying that the substrate may include other layers without departing from the spirit of the present invention. Details of the other layers will be described later.

[0015] <Layer Structure of the Multilayer> The layer structure of the multilayer of this embodiment will be described with reference to Figure 1. It goes without saying that the multilayer of this embodiment is not limited to that shown in Figure 1. Figure 1 is a schematic cross-sectional view showing an example of the multilayer of this embodiment, where 1 is the multilayer, 2 is (a) a (meth)acrylate-based hard coat layer, 3 is (b) a thermoplastic acrylic resin layer, 4 is (c) a polycarbonate resin layer, and 5 is (d) a (meth)acrylate-based hard coat layer.

[0016] In this embodiment, a hard coat layer is provided on each surface of the substrate. Preferably, a hard coat layer is provided on each surface of the substrate. By providing a hard coat layer in this way, the surface hardness of the resulting multilayer can be increased. The multilayer of this embodiment may have other layers as long as it has (a) a (meth)acrylate-based hard coat layer, (b) a thermoplastic acrylic resin layer, (c) a polycarbonate resin layer, and (d) a (meth)acrylate-based hard coat layer in this order, without departing from the spirit of this embodiment. However, it is preferable that there are no other layers, that is, that they are adjacent to each other.

[0017] Other layers that the multilayer and / or substrate of this embodiment may have include an anti-reflective layer, a polarizing layer, an adhesive layer, a sticky layer, an anti-fouling layer, an infrared-cutting layer, and the like. The substrate may include an adhesive layer and / or a sticky layer. Between the substrate and the hard coat layer, at least one of an anti-reflective layer, a polarizing layer, an adhesive layer, a sticky layer, an anti-fouling layer, and an infrared-cutting layer may be included. The surface of the hard coat layer may include at least one of an anti-reflective layer, a polarizing layer, an anti-fouling layer, and an infrared-cutting layer. One example of the multilayer of this embodiment is having an anti-reflective layer. Another example of the multilayer of this embodiment is having a polarizing layer. Having an anti-reflective layer and / or a polarizing layer makes it preferably used as a dust cover for a head-up display. One example of the multilayer of this embodiment having a polarizing layer has a layer configuration of the multilayer of this embodiment / adhesive layer / polarizing layer (polarizing film) / polycarbonate film. Here, it is preferable that the multilayer of this embodiment is in contact with the adhesive layer on the (c) polycarbonate resin layer side. Furthermore, in the above embodiment, a (d) (meth)acrylate-based hard coat layer is provided between the (c) polycarbonate resin layer and the adhesive layer, that is, on the surface of the (c) polycarbonate resin layer. In the multilayer body, the polycarbonate film provided on the opposite side of the polarizing film (the side on which the multilayer body of this embodiment is not bonded) is preferably the same as the (c) polycarbonate resin layer.

[0018] As the adhesive, any known adhesive can be used, with acrylic adhesives and urethane adhesives being preferred.

[0019] Furthermore, the multilayer body may have at least one of the following treatments applied to at least one of its surfaces: anti-fingerprint treatment, anti-glare treatment, weather-resistant treatment, antistatic treatment, anti-fouling treatment, and anti-blocking treatment. An example of the outermost surface of the multilayer body in this case is a hard coat layer. Anti-blocking treatment refers to a treatment that allows films to be easily separated even if they are in close contact with each other, and examples include adding an anti-blocking agent or creating irregularities on the surface of the multilayer body.

[0020] There are no particular restrictions on the thickness (total thickness) of the multilayer, but it is preferably 30 μm or more, and more preferably 100 μm or more. Furthermore, the thickness of the multilayer is preferably 10,000 μm or less, more preferably 5,000 μm or less, even more preferably 2,000 μm or less, and may also be 1,000 μm or less, or 500 μm or less.

[0021] The multilayer material of this embodiment preferably has a high pencil hardness (hardness). Specifically, the pencil hardness of the multilayer material of this embodiment, measured from the (meth)acrylate-based hard coat layer side under a 500g load, is preferably H or higher, and more preferably 2H or higher. There is no upper limit, but 3H or lower is practical.

[0022] The multilayer of this embodiment is also preferably excellent in transparency. Specifically, the haze of the multilayer is 20% or less, preferably 10% or less, more preferably 5% or less, even more preferably 3% or less, even more preferably 2% or less, even more preferably 1.5% or less, even more preferably 1% or less, particularly preferably 0.8% or less, and may be 0.5% or less. The lower limit is preferably 0% or more, but greater than 0% is practical. Such low haze is due to the particle size (D) of the inorganic particles. ５０ This is achieved by reducing the average of the ) to less than 120 nm. The haze is measured (in %) of the obtained multilayer under the conditions of a D65 light source and a 10° field of view. A haze meter (HM-150, manufactured by Murakami Color Technology Laboratory Co., Ltd.) can be used for measurement.

[0023] The multilayer material of this embodiment is also preferably excellent in flame retardancy. Specifically, the multilayer material is preferably satisfied with a C rating in the FMVSS test (burns up to the B standard line but the burning rate is 102 mm / min or less), more preferably satisfied with a B rating in the FMVSS test (burns within 51 mm (and within 60 seconds) of the A standard line and self-extinguishes), and even more preferably satisfied with an A rating (the test piece does not ignite or self-extinguishes before reaching the A standard line). Pencil hardness and FMVSS testing are measured according to the examples described below.

[0024] The method for manufacturing the multilayer body of this embodiment is not particularly defined. The multilayer body of this embodiment can be manufactured, for example, by using (c) a main extruder for extruding a polycarbonate resin layer-forming composition and (b) a sub-extruder for extruding a thermoplastic acrylic resin layer-forming composition, melting the resins according to the conditions of the resins used in each case, guiding them to an extrusion die, laminating them inside the die to form a sheet, or forming a base material by laminating after forming a sheet, and then forming a hard coat layer.

[0025] The multilayer body of this embodiment may be used as is, but it can be processed, particularly by heat processing, to form a molded product. The molded product of this embodiment is a molded product formed from the multilayer body of this embodiment.

[0026] <Hard Coat Layer> The multilayer body of this embodiment has hard coat layers ((a) a (meth)acrylate-based hard coat layer and (d) a (meth)acrylate-based hard coat layer) on both sides of the substrate. By having these hard coat layers, a multilayer body with high surface hardness and excellent flame retardancy can be obtained. In this embodiment, the (a) (meth)acrylate-based hard coat layer and the (d) (meth)acrylate-based hard coat layer may be the same or different, but it is preferable that they be different.

[0027] The hard coat layer used in this embodiment is a (meth)acrylate-based hard coat layer. More specifically, it is preferable to obtain a hard coat layer obtained by applying and curing a hard coat material containing (meth)acrylate. The hard coat layer preferably contains components derived from monofunctional or polyfunctional (preferably polyfunctional, more preferably 2 to 10 functional) (meth)acrylate, and more preferably contains components derived from monofunctional or polyfunctional (preferably polyfunctional, more preferably 2 to 10 functional) urethane (meth)acrylate. In particular, the components derived from urethane (meth)acrylate are preferably 3 to 10 functional, and more preferably 4 to 8 functional. In addition to (meth)acrylate, the hard coat material preferably contains a photopolymerization initiator. In this embodiment, it is preferable that (a) the (meth)acrylate-based hard coat layer contains components derived from polyfunctional urethane (meth)acrylate. In this embodiment, it is preferable that (d) the (meth)acrylate-based hard coat layer contains components derived from polyfunctional urethane (meth)acrylate. In this embodiment, it is preferable that both the (a) (meth)acrylate-based hard coat layer and the (d) (meth)acrylate-based hard coat layer contain components derived from polyfunctional urethane (meth)acrylate.

[0028] The hard coat layer used in this embodiment contains inorganic particles in a proportion of 20 to 80% by mass of the hard coat layer. By including such a large amount of inorganic particles, a multilayer material with excellent flame retardancy can be obtained. The inorganic particle content is preferably 25% by mass or more, more preferably 30% by mass or more, even more preferably 35% by mass or more, preferably 70% by mass or less, more preferably 60% by mass or less, even more preferably 50% by mass or less, and even more preferably 45% by mass or less, based on 100% by mass of the hard coat layer. Setting the content above the lower limit tends to further improve the flame retardancy of the multilayer material. Setting the content below the upper limit tends to reduce the likelihood of cracking during heat resistance tests and wet heat tests, and also tends to improve the transparency of the multilayer material. The hard coat layer in this embodiment may contain only one type of inorganic particle, or it may contain two or more types. When two or more types of inorganic particles are included, it is preferable that the total amount is within the above range.

[0029] The particle size (D) of the inorganic particles ５０ The average of the particles (D) is preferably 1 nm or more, more preferably 5 nm or more, even more preferably 10 nm or more, preferably less than 120 nm, and more preferably 110 nm or less. Setting it above the lower limit tends to improve the flame retardancy of the resulting multilayer. Setting it below the upper limit tends to improve the transparency of the resulting multilayer. The hard coat layer in this embodiment may contain only one type of inorganic particle, or it may contain two or more types. When it contains two or more types of inorganic particles, it is preferable that the total amount is within the above range. Note that in this specification, particle size (D) ５０ The values ​​are those measured using a laser diffraction particle size distribution analyzer (Shimadzu Corporation, model number: SALD-2300).

[0030] Preferred examples of inorganic particles include nanoparticles made of metals or metal compounds. Examples include gold, silver, copper, platinum, palladium, nickel, cobalt, iron, manganese, silicon, titanium, zirconium, tungsten, molybdenum, chromium, zinc, aluminum, and composite metals made of two or more of these. Preferred metal compounds include, for example, iron oxide, silicon oxide (silica), zirconium oxide, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, tungsten oxide, cobalt oxide, nickel oxide, cerium oxide, cupric oxide, zinc oxide, tin oxide, antimony trioxide (ATO), titanium dioxide, aluminum oxide, indium tin oxide (ITO), tungsten cesium oxide (CWO), and mixtures thereof, as well as metal oxides, metal carbides, metal borides, metal carbonates, zeolites, clays, and composites thereof. The inorganic particles contained in the hard coat layer of this embodiment preferably include at least one metal oxide, and more preferably include at least one selected from the group consisting of silica, antimony trioxide, and tungsten cesium oxide.

[0031] A preferred example of this embodiment is that (a) the (meth)acrylate hard coat layer contains silica, and (d) the (meth)acrylate hard coat layer contains antimony trioxide and / or tungsten cesium oxide. With such a configuration, a multilayer with superior surface hardness and flame retardancy tends to be obtained. Furthermore, in (a) the (meth)acrylate hard coat layer, the total of components derived from monofunctional or polyfunctional (preferably polyfunctional, more preferably 2 to 10 functional) urethane (meth)acrylate and inorganic particles (preferably silica) preferably accounts for 90% by mass or more, and more preferably 93% by mass or more. On the other hand, in the (d) (meth)acrylate-based hard coat layer, the total of components derived from 4-10 functional urethane (meth)acrylate, components derived from bifunctional (meth)acrylate, and inorganic particles (preferably antimony trioxide and / or tungsten cesium oxide) preferably accounts for 90% by mass or more, and more preferably 93% by mass or more.

[0032] In addition to the above components, the hard coat layer may also contain leveling agents, organic pigments, ultraviolet absorbers, light stabilizers, heat stabilizers, flame retardants, flame retardant additives, colorants, antistatic agents, fluorescent whitening agents, antifogging agents, flow modifiers, plasticizers, dispersants, antibacterial agents, antiblocking agents, impact modifiers, sliding modifiers, hue modifiers, acid trapping agents, etc. One of these components may be used, or two or more may be used in combination.

[0033] Examples of flame retardants include halogen-based flame retardants and phosphorus-based flame retardants. Examples of phosphorus-based flame retardants include aromatic phosphate ester compounds, phosphaphenanthrene compounds, metal phosphinate salts, ammonium polyphosphate, melamine polyphosphate, phosphate ester amides, and red phosphorus. As the flame retardant, the descriptions in paragraphs 0054 to 0082 of JP-A-2022-104214 and paragraphs 0052 to 0077 of Patent No. 7021724 can be referred to, and this content is incorporated herein. However, the hard coat layer in the present embodiment can also be configured to substantially not contain a flame retardant. Substantially not containing means that the content of the flame retardant contained in the hard coat layer in the present embodiment is 0.1% by mass or less in the hard coat layer, preferably less than 0.1% by mass, more preferably less than 0.07% by mass, further preferably less than 0.05% by mass, still more preferably less than 0.03% by mass, and even more preferably less than 0.01% by mass.

[0034] The thickness of the hard coat layer is preferably 0.5 μm or more, more preferably 1 μm or more, further preferably 2 μm or more, still more preferably 2.5 μm or more, and even more preferably 3 μm or more. Also, it is preferably 20 μm or less, more preferably 15 μm or less, further preferably 12 μm or less, still more preferably 10 μm or less, even more preferably 8 μm or less, and may be 5 μm or less. By setting it to be not less than the lower limit value, the pencil hardness of the entire multilayer body by the hard coat layer tends to be further improved. By setting it to be not more than the upper limit value, the flame retardancy tends to be further improved.

[0035] <(b) Thermoplastic acrylic resin layer> The (b) thermoplastic acrylic resin layer in the present embodiment contains an acrylic resin. The acrylic resin is usually a layer containing a polymer of (meth)acrylate and / or a copolymer of (meth)acrylate and other monomers. Also, the (b) thermoplastic acrylic resin layer may be a single layer or a multilayer, but a single layer is preferred.

[0036] (b) The thermoplastic acrylic resin layer in the present embodiment contains an acrylic resin as described above. An example of the acrylic resin is preferably a polymer containing 50% by mass or more (preferably 90% by mass or more) of alkyl (meth)acrylate units (preferably alkyl methacrylate units) in all the constituent units, and more preferably a polymer containing 50% by mass or more (preferably 90% by mass or more) of methyl (meth)acrylate units (preferably methyl methacrylate units) in all the constituent units. Examples of the constituent units other than the alkyl (meth)acrylate units include other (meth)acrylate units, styrene units, cyclic acid anhydride units, N-substituted maleimide units, and lactone ring units.

[0037] (b) The thermoplastic acrylic resin layer may consist only of an acrylic resin, or may contain other thermoplastic resins in addition to the acrylic resin. As the other thermoplastic resins, it is more preferable to contain at least one thermoplastic resin selected from styrenic resins, fluorine-based resins such as polyvinylidene fluoride, and aromatic polyether resins such as polyphenylene ether, and it is even more preferable to contain a styrenic resin.

[0038] An example of (b) the thermoplastic acrylic resin layer is a layer composed of 90% by mass or more (preferably 95% by mass or more, more preferably 97% by mass or more, even more preferably 98% by mass or more) of an acrylic resin.

[0039] The weight average molecular weight of the acrylic resin is not particularly defined, but is preferably 10,000 or more, more preferably 30,000 or more, even more preferably 50,000 or more, still more preferably 60,000 or more, and even more preferably 70,000 or more. Also, the weight average molecular weight of the acrylic resin is preferably 250,000 or less, more preferably 200,000 or less, even more preferably 150,000 or less, still more preferably 100,000 or less, and even more preferably 90,000 or less.

[0040] The glass transition temperature of the thermoplastic acrylic resin layer (b) used in this embodiment is preferably 80°C or higher, more preferably 90°C or higher, even more preferably 95°C or higher, even more preferably 100°C or higher, and even more preferably 105°C or higher. There is no particular upper limit, but for example, 200°C or lower is practical. The glass transition temperature is measured according to the description in paragraph 0056 of Japanese Patent Application Publication No. 2022-080270.

[0041] (b) The thermoplastic acrylic resin layer may contain, in addition to the above components, inorganic particles, antioxidants, mold release agents, ultraviolet absorbers, heat stabilizers, flame retardants, flame retardant aids, colorants, antistatic agents, fluorescent whitening agents, antifogging agents, flow modifiers, plasticizers, dispersants, antibacterial agents, antiblocking agents, impact modifiers, sliding modifiers, hue modifiers, acid trapping agents, etc. One of these components may be used, or two or more may be used in combination. The total content of the above components is preferably 0 to 5% by mass of the (b) thermoplastic acrylic resin layer, more preferably 0 to 3% by mass, even more preferably 0 to 1% by mass, even more preferably 0 to 0.5% by mass, even more preferably 0 to 0.3% by mass, and even more preferably 0 to 0.1% by mass.

[0042] As described above, the thermoplastic acrylic resin layer (b) in this embodiment may contain a flame retardant. Examples of flame retardants that may be included in the thermoplastic acrylic resin layer (b) include phosphorus-based flame retardants and metal salts, with metal salts being preferred. However, the thermoplastic acrylic resin layer (b) in this embodiment may also be configured to be substantially free of flame retardants. Substantially free means that the amount of flame retardant contained in the thermoplastic acrylic resin layer (b) in this embodiment is 0.1% by mass or less, preferably less than 0.1% by mass, more preferably less than 0.07% by mass, even more preferably less than 0.05% by mass, even more preferably less than 0.03% by mass, and even more preferably less than 0.01% by mass.

[0043] (b) The thickness of the thermoplastic acrylic resin layer is 15 μm or more, preferably 20 μm or more, more preferably 25 μm or more, even more preferably 30 μm or more, and also 80 μm or less, preferably 70 μm or less, more preferably 60 μm or less, even more preferably 50 μm or less, even more preferably 45 μm or less, and even more preferably 40 μm or less. Setting it above the lower limit makes molding easier and tends to improve hardness. Setting it below the upper limit tends to improve the flame retardancy of the multilayer.

[0044] <(c) Polycarbonate resin layer> The (c) polycarbonate resin layer in this embodiment includes a polycarbonate resin. The polycarbonate resin is not particularly limited as long as it contains a carbonate ester bond-containing -[O-R-OCO]- constituent unit (where R is a hydrocarbon group (for example, an aliphatic group, an aromatic group, or a group containing both an aliphatic and an aromatic group, and further having a linear or branched structure)) in the molecular main chain, and various polycarbonate resins can be used, with aromatic polycarbonate resins being preferred.

[0045] In this embodiment, the polycarbonate resin preferably includes a bisphenol-type polycarbonate resin. A bisphenol-type polycarbonate resin means that 80 mol% or more, preferably 90 mol% or more, and more preferably 95 mol% or more of the constituent units of the polycarbonate resin are carbonate constituent units derived from bisphenol and / or its derivatives. The bisphenol and / or its derivatives are preferably bisphenol A, bisphenol AP, bisphenol C, bisphenol BP, or derivatives thereof, more preferably bisphenol A, bisphenol AP, or derivatives thereof, and even more preferably bisphenol A or its derivatives. The bisphenol-type polycarbonate resin is preferably a bisphenol A-type polycarbonate resin.

[0046] The molecular weight of the polycarbonate resin is not specifically defined, but it is usually preferably 20,000 or more, more preferably 21,000 or more, and may be 22,000 or more, calculated from the viscosity-average molecular weight of the solution measured at 25°C using methylene chloride as the solvent. Furthermore, the viscosity-average molecular weight is preferably 35,000 or less, more preferably 32,000 or less, and even more preferably 30,000 or less. By setting the viscosity-average molecular weight above the lower limit, the strength of the resulting flat molded article can be increased. Also, by setting the viscosity-average molecular weight below the upper limit, the moldability tends to improve. Here, the viscosity-average molecular weight [Mv] is calculated by using methylene chloride as the solvent, determining the intrinsic viscosity [η] (unit dL / g) at 25°C using an Ubbelohde viscometer, and using Schnell's viscosity formula, i.e., η = 1.23 × 10⁻⁶. －４ Mv ０．８３ It refers to the value calculated from [the formula]. Furthermore, intrinsic viscosity [η] is the specific viscosity [η] at each solution concentration [C] (g / dL). ｓｐ This value was calculated by measuring [the value] and using the following formula. In this embodiment, two or more polycarbonate resins with different viscosity-average molecular weights may be mixed and used; in this case, the viscosity-average molecular weight of the mixture shall be used.

[0047] The starting glass transition temperature (Tg) of the polycarbonate resin used in this embodiment is preferably 160°C or lower, more preferably 155°C or lower, even more preferably 154°C or lower, even more preferably 153°C or lower, even more preferably 152°C or lower, and even more preferably 151°C or lower. Furthermore, the starting glass transition temperature (Tg) of the polycarbonate resin used in this embodiment may be, for example, 140°C or higher, and may also be 143°C or higher, 145°C or higher, 147°C or higher, or 148°C or higher. The glass transition temperature is measured according to the description in paragraph 0056 of Japanese Patent Application Publication No. 2022-080270.

[0048] Further details regarding the polycarbonate resin can be found in paragraphs 0011 to 0020 of Japanese Patent Application Publication No. 2012-144604 and paragraphs 0014 to 0035 of Japanese Patent Application Publication No. 2019-002023, without departing from the spirit of this embodiment, and these contents are incorporated herein.

[0049] In this embodiment, the polycarbonate resin content in the (c) polycarbonate resin layer is preferably 90% by mass or more, more preferably 92% by mass or more, even more preferably 94% by mass or more, even more preferably 96% by mass or more, even more preferably 97% by mass or more, and may be 98% by mass or more, based on 100% by mass of the (c) polycarbonate resin layer. The upper limit may be 100% by mass. If the (c) polycarbonate resin layer in this embodiment contains two or more types of polycarbonate resin, it is preferable that the total amount is within the above range.

[0050] In this embodiment, the (c) polycarbonate resin layer may or may not contain a flame retardant. Examples of flame retardants include organometallic salts, halogenated flame retardants, and phosphorus-based flame retardants. Examples of phosphorus-based flame retardants include aromatic phosphate ester compounds, phosphaphenanthrene compounds, phosphinate metal salts, ammonium polyphosphate, melamine polyphosphate, phosphate ester amides, and red phosphorus, with organometallic salts and / or phosphinate metal salts being preferred, organometallic salts more preferred, and benzenesulfonic acid metal salts even more preferred. In addition to the above, the descriptions in paragraphs 0054 to 0082 of Japanese Patent Application Publication No. 2022-104214 and paragraphs 0052 to 0077 of Japanese Patent No. 7021724 can also be considered as flame retardants, and this content is incorporated herein.

[0051] In this embodiment, if the (c) polycarbonate resin layer contains a flame retardant, its content is preferably 0.01% by mass or more, preferably less than 0.1% by mass, and more preferably less than 0.05% by mass. However, the (c) polycarbonate resin layer in this embodiment may also be configured to be substantially free of flame retardants. Substantially free means that the amount of flame retardant contained in the (c) polycarbonate resin layer in this embodiment is 0.1% by mass or less, preferably less than 0.1% by mass, more preferably less than 0.07% by mass, even more preferably less than 0.05% by mass, even more preferably less than 0.03% by mass, even more preferably less than 0.01% by mass, and may even be less than 0.001% by mass. The multilayer of this embodiment is highly valuable in that it can achieve flame retardancy even if the (c) polycarbonate resin layer is substantially free of flame retardants.

[0052] In this embodiment, the (c) polycarbonate resin layer may contain, in addition to the above components, antioxidants, mold release agents, ultraviolet absorbers, flame retardant aids, heat stabilizers, colorants, antistatic agents, fluorescent whitening agents, antifogging agents, flow improvers, plasticizers, dispersants, antibacterial agents, antiblocking agents, impact improvers, sliding improvers, hue improvers, acid trapping agents, etc. One of these components may be used, or two or more may be used in combination. The total content of the above components is preferably 0 to 5% by mass of the (c) polycarbonate resin layer, more preferably 0 to 3% by mass, even more preferably 0 to 1% by mass, even more preferably 0 to 0.5% by mass, even more preferably 0 to 0.3% by mass, and even more preferably 0 to 0.1% by mass.

[0053] Examples of antioxidants include phenolic antioxidants, amine antioxidants, phosphorus-based antioxidants, and thioether-based antioxidants. In this embodiment, phosphorus-based antioxidants and phenolic antioxidants (more preferably hindered phenolic antioxidants) are preferred, and phosphorus-based antioxidants are even more preferred.

[0054] The phosphorus-based antioxidant is preferably a phosphite-based antioxidant, and a phosphite compound represented by the following formula (1) or (2) is preferred. (In formula (1), R １１ and R １２ each independently represent an alkyl group having 1 to 30 carbon atoms or an aryl group having 6 to 30 carbon atoms.) (In formula (2), R １３ to R １７ each independently represent a hydrogen atom, an aryl group having 6 to 20 carbon atoms, or an alkyl group having 1 to 20 carbon atoms.)

[0055] In the above formula (1), the alkyl groups represented by R １１ , R １２ are each independently preferably a linear or branched alkyl group having 1 to 10 carbon atoms. When R １１ , R １２ are aryl groups, an aryl group represented by any one of the following formulas (1-a), (1-b), or (1-c) is preferred. * in the formula represents the bonding position.

[0056] (In formula (1-a), R Ａ each independently represent an alkyl group having 1 to 10 carbon atoms. In formula (1-b), R Ｂ each independently represent an alkyl group having 1 to 10 carbon atoms.)

[0057] As the hindered phenol-based antioxidant, reference can be made to the descriptions in paragraph 0063 of JP-A No. 2018-090677 and paragraph 0076 of JP-A No. 2018-188496, and this content is incorporated herein.

[0058] In addition to the above, the antioxidant can take into account the descriptions in paragraphs 0057 to 0061 of JP-A No. 2017-031313, and this content is incorporated herein.

[0059] The antioxidant content is preferably 0.001 parts by mass or more, more preferably 0.005 parts by mass or more, even more preferably 0.010 parts by mass or more, even more preferably 0.050 parts by mass or more, and also preferably 0.500 parts by mass or less, more preferably 0.300 parts by mass or less, even more preferably 0.200 parts by mass or less, even more preferably 0.150 parts by mass or less, even more preferably 0.100 parts by mass or less, and especially most preferably 0.080 parts by mass or less. Only one type of antioxidant may be used, or two or more types may be used. When two or more types are used, it is preferable that the total amount is within the above range.

[0060] Next, (c) release agents that may be included in the polycarbonate resin layer will be described. There is no specific type of release agent, but examples include aliphatic carboxylic acids, esters of aliphatic carboxylic acids and alcohols, aliphatic hydrocarbon compounds with a number average molecular weight of 200 to 15,000, polyethers with a number average molecular weight of 100 to 5,000, and polysiloxane-based silicone oils.

[0061] Details of the release agent can be found in paragraphs 0035-0039 of International Publication No. 2015 / 190162, which are incorporated herein by reference.

[0062] The release agent content is preferably 0.001 parts by mass or more, more preferably 0.005 parts by mass or more, even more preferably 0.010 parts by mass or more, and even more preferably 0.050 parts by mass or more, per 100 parts by mass of the polycarbonate resin layer (c). The upper limit is preferably 0.5 parts by mass or less, more preferably 0.3 parts by mass or less, and even more preferably 0.1 parts by mass or less. Only one type of release agent may be used, or two or more types may be used. When two or more types are used, it is preferable that the total amount is within the above range.

[0063] (c) The thickness of the polycarbonate resin layer is preferably 50 μm or more, more preferably 100 μm or more, and even more preferably 150 μm or more. Setting it above the lower limit makes molding easier and tends to improve flame retardancy. Also, the upper limit of the thickness of the (c) polycarbonate resin layer is preferably 1000 μm or less, more preferably 750 μm or less, and even more preferably 500 μm or less.

[0064] <Applications> The multilayer material of this embodiment may be used as is, but it can also be molded into a product by processing, particularly by heat processing, and further by heat bending. The multilayer material of this embodiment can be suitably used for optical components, decorative products, anti-reflective molded articles, etc. The multilayer material of this embodiment can be suitably used for display devices, electrical and electronic equipment, office automation equipment, portable information terminals, machine parts, home appliances, vehicle parts, various containers, lighting equipment, and other components. Among these, it can be suitably used in various displays, electrical and electronic equipment, office automation equipment, housings for portable information terminals and home appliances, lighting equipment and vehicle parts (especially vehicle interior parts), surface films for smartphones and touch panels, optical materials, and optical discs. In particular, the multilayer material of this embodiment can be suitably used as a dust cover for head-up displays.

[0065] The present invention will be described in more detail below with reference to examples. The materials, amounts used, proportions, processing content, processing procedures, etc., shown in the following examples can be modified as appropriate, as long as they do not depart from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below. If the measuring instruments, etc., used in the examples are difficult to obtain due to discontinuation or other reasons, measurements can be taken using other instruments with equivalent performance.

[0066] 1. Raw Materials <Composition for forming a hard coat layer> Urethane acrylate: UN-3320HC, solid content 100% by mass, weight-average molecular weight 1,500, number of functional groups 6, manufactured by Negami Kogyo Co., Ltd. DCP-A: Tricyclodecanedimethanol diacrylate, solid content 100% by mass, molecular weight 304, number of functional groups 2, manufactured by Shin Nakamura Chemical Co., Ltd. BP-4EAL: Diacrylate, an EO adduct of bisphenol A; solid content 100% by mass; molecular weight 512; number of functional groups 2; manufactured by Kyoeisha Chemical Co., Ltd.

[0067] ATO: Antimony trioxide dispersion, ATO content 17% by mass, manufactured by Mitsubishi Materials Electronic Chemicals Co., Ltd., average particle diameter (D ５０ ) 100 nm CWO: YMF-02A, cesium tungsten oxide dispersion, CWO content 18.5% by mass, manufactured by Sumitomo Metal Mining Co., Ltd., average particle diameter (D ５０ ) 10-100 nm Silica: PGM-AC-2140Y, silica particle dispersion, silica particle content 42% by mass, manufactured by Nissan Chemical Corporation, average particle diameter (D ５０ ) 12 nm Esacre One: Photopolymerization initiator, manufactured by IGM Resins Omnirad 819: Acylphosphine oxide-based photopolymerization initiator, 100% solids by mass, manufactured by IGM Resins B.V BYK-UV3550: Leveling agent, manufactured by Bic Chemie

[0068] Compositions No. 1 to No. 6 for forming a hard coat layer were obtained by mixing each component shown in Table 1 below with an arbitrary proportion of propylene glycol monomethyl ether and stirring. In Table 1, the proportion of each component indicates the solid content (mass%).

[0069] <(b) Materials for the thermoplastic acrylic resin layer> ・Acrylic resin PMMA: Polymethyl methacrylate, manufactured by Asahi Kasei Corporation, Delpet 80HD

[0070] <(c) Materials for the polycarbonate resin layer> ・Polycarbonate resin E-2000F: Polycarbonate resin obtained by interfacial polymerization using bisphenol A as a starting material (manufactured by Mitsubishi Gas Chemical Company, Inc., E-2000F, viscosity-average molecular weight: 27,000, Tg: 150℃) S-3000F: Polycarbonate resin obtained by interfacial polymerization using bisphenol A as a starting material (manufactured by Mitsubishi Gas Chemical Company, Inc., S-3000F, viscosity-average molecular weight: 21,000, Tg: 147℃)

[0071] - Antioxidant 2112: Tris(2,4-di-tert-butylphenyl) phosphite (phosphorus-based antioxidant, ADEKA Corporation's ADEKA Stab 2112) - Release agent S-100A: Glycerin monostearate (Riken Vitamin Co., Ltd.'s Rikemar S-100A) - Flame retardant KSS-FR: Arichem's KSS-FR, potassium diphenylsulfon-3-sulfonate

[0072] (c) A resin composition (pellets) for forming a polycarbonate resin layer was manufactured according to the following method. Each of the components described above was weighed to the amount shown in Table 2 (each component in Table 2 is expressed in mass %). After mixing in a tumbler for 15 minutes, the mixture was melt-kneaded using a twin-screw extruder with a screw diameter of 32 mm and a vent (TEX30α, manufactured by Japan Steel Works, Ltd.), and pellets were obtained by strand cutting. The resin composition (pellets) for forming a polycarbonate resin layer was melt-kneaded at 260 to 300°C, which was changed as needed depending on the resin viscosity.

[0073] <(b) Manufacturing of a base material 1 consisting of a thermoplastic acrylic resin layer and a polycarbonate resin layer> A multilayer body was formed using a multilayer extrusion apparatus having a single-screw extruder with a shaft diameter of 32 mm, a single-screw extruder with a shaft diameter of 65 mm, a feed block connected to all extruders, and a 650 mm wide T-die connected to the feed block. Acrylic resin (PMMA, pellets) was introduced into the single-screw extruder with a shaft diameter of 32 mm and extruded under conditions of a cylinder temperature of 240°C and a discharge rate of 0.3 to 6.4 kg / h. In addition, the resin composition (pellets) for forming the polycarbonate resin layer obtained above was continuously introduced into the single-screw extruder with a shaft diameter of 65 mm, and the discharge rate was extruded at 17.4 to 23.5 kg / h while the cylinder temperature was changed as needed between 250°C and 290°C depending on the resin viscosity. The feed block connected to all extruders was equipped with two types of two-layer distribution pins and was used for extrusion and lamination. The material was extruded into a sheet using a T-die connected to the end of the die, and cooled while transferring a mirror finish using three mirror-finishing rolls at temperatures of 120°C, 120°C, and 140°C from the upstream side, to obtain a multilayer body consisting of (c) a polycarbonate resin layer and (b) a thermoplastic acrylic resin layer. The total thickness of the obtained multilayer bodies was 375 μm in all cases. The thickness of the (b) thermoplastic acrylic resin layer of the obtained multilayer bodies was 5 μm, 25 μm, 35 μm, 55 μm, or 100 μm, respectively.

[0074] <(c) Manufacturing of base material 2 consisting only of a polycarbonate resin layer> Molding was carried out using a single-screw extruder with a shaft diameter of 65 mm, a feed block connected to the extruder, and a single-layer extruder having a 650 mm wide T-die connected to the feed block. Under conditions of a cylinder temperature of 280°C, the (c-3) polycarbonate resin layer forming resin composition (pellets) described in Table 2 was continuously introduced and extruded. The material was extruded into a sheet shape by the T-die connected to the extruder, and a single-layer film consisting of a polycarbonate resin layer containing the (c-3) polycarbonate resin layer forming resin composition (pellets) was obtained by cooling while transferring a mirror finish using three mirror-finishing rolls with temperatures of 120°C, 120°C, and 140°C from the upstream side. At this time, the extrusion amount and roll speed were appropriately changed so that the thickness of the single-layer film was 200 μm.

[0075] 2. Examples 1-7, Comparative Examples 1-4 As shown in Tables 3-5, a substrate 1 consisting of a (b) thermoplastic acrylic resin layer and a (c) polycarbonate resin layer, using (C-1) as the polycarbonate in a resin composition (pellets) for forming a polycarbonate resin layer, was used. The hard coat layer forming compositions shown in Tables 3-5 were applied to the surface of the (b) thermoplastic acrylic resin layer of the substrate using a bar coater. The applied hard coat layer forming compositions were dried in an oven at 80°C for 3 minutes, and then exposed to an integrated light intensity of 500 mJ / cm² under a nitrogen atmosphere using a UV irradiation machine manufactured by Heraeus, Inc. ２ (U-Oak UV irradiometer, measurement wavelength 360 nm) The material was cured to achieve the following result. (c) The same procedure was followed on the surface of the polycarbonate resin layer.

[0076] <FMVSS Test> For the multilayer material obtained above, an FMVSS No. 302 flammability test apparatus was used to indirectly ignite a burner flame 38 mm from the right end of the test piece (350 mm × 100 mm × 0.375 mm) for 15 seconds, and the combustion rate at a combustion distance of 254 mm between the markings was measured. The test fixture was measured without wire and evaluated as follows: A: The test piece did not ignite or self-extinguished before the A standard line B: Self-extinguished within 51 mm (and within 60 seconds) of the A standard line C: Burned up to the B standard line, but the combustion rate was 102 mm / min or less D: Burned up to the B standard line, and the combustion rate was faster than 102 mm / min

[0077] <Pencil Hardness> The pencil hardness of the surface of the thermoplastic acrylic resin layer (b) of the multilayer body prepared above was determined using a pencil hardness tester with a 500g load, in accordance with JIS K5600-5-4:1999. The evaluation was performed by five experts and decided by majority vote. A: 2H or higher B: H C: Less than H

[0078] <Overall Evaluation> The following criteria were used for evaluation: 6: FMVSS test evaluation is A and pencil hardness evaluation is A 5: FMVSS test evaluation is A and pencil hardness evaluation is B 4: FMVSS test evaluation is B (pencil hardness evaluation is A or B) 3: FMVSS test evaluation is C and pencil hardness evaluation is A 2: FMVSS test evaluation is C and pencil hardness evaluation is B 1: FMVSS test evaluation is D and / or pencil hardness evaluation is C

[0079] Example 8 (c) A laminate was obtained in the same manner as in Example 1, except that the resin composition (pellets) for forming the polycarbonate resin layer used in the polycarbonate resin layer was changed to (C-2).

[0080] Furthermore, a polyvinyl alcohol film (manufactured by Kuraray Co., Ltd., VF-PS#7500) was swollen in water at 35°C, dyed in an aqueous solution at 35°C containing the dichroic dyes Karayas Blue G (C.I. Blue 78), Sumilight Red 4B (C.I. Red 81), chrysophenine (C.I. Yellow 12), and 10 g / L of anhydrous sodium sulfate, and then immersed in an aqueous solution containing 2.5 g / L of nickel acetate and 5 g / L of boric acid. The film was gradually stretched during this process until it was four times its original size. While maintaining the tension of the film, it was heated at 110°C for 3 minutes to obtain a polarizing film with a thickness of 30 μm. A thermosetting polyurethane adhesive (manufactured by Toyo Morton Co., Ltd., main component: BHS-6020A, curing agent: BHS-6020C, solid content concentration: 30% by mass) was applied to one side of the polarizing film described above. Then, the film was bonded to the hard coat surface of the polycarbonate resin layer of the multilayer obtained earlier, with the stretch axis aligned, to obtain a one-sided laminated product. Next, the thermosetting polyurethane adhesive described above was applied to the unbonded side of the one-sided laminated product, and a polycarbonate film (manufactured by Mitsubishi Gas Chemical Co., Ltd., S-2000, thickness: 200 μm, flame retardant-free) was bonded to it, with the stretch axis aligned. A laminator (manufactured by MCK Co., Ltd., MP-630A) was used for bonding, with the laminator roll set to 60°C, the roll rotation speed to 1.5 m / min, and the bonding pressure to 0.5 MPa. The obtained multilayer was evaluated for FMVSS testing and pencil hardness in the same manner as in Example 1.

[0081] Example 9 (c) A multilayer was obtained in the same manner as in Example 1, except that the resin composition (pellets) for forming the polycarbonate resin layer used in the polycarbonate resin layer was changed to (C-2).

[0082] Furthermore, a thermosetting polyurethane adhesive (manufactured by Toyo Morton Co., Ltd., main component: BHS-6020A, curing agent: BHS-6020C, solid content concentration: 30% by mass) was applied to one side of a polarizing film prepared by the same process as in Example 8. Then, the film was bonded to the hard coat surface on the polycarbonate resin layer side of the multilayer obtained earlier, with the stretch axis aligned, to obtain a one-sided laminated product. Next, the thermosetting polyurethane adhesive was applied to the unbonded side of the one-sided laminated product, and a 200 μm thick polycarbonate film was bonded to it, with the stretch axis aligned. The polycarbonate film used was the base material 2 consisting only of the polycarbonate resin layer described above (c). A laminator (manufactured by M.C.K. Co., Ltd., MP-630A) was used for bonding, with the laminator roll set to 60°C, the roll rotation speed to 1.5 m / min, and the bonding pressure to 0.5 MPa. The obtained multilayer was evaluated for FMVSS testing and pencil hardness in the same manner as in Example 1.

[0083] Example 10 (c) A multilayer was obtained in the same manner as in Example 1, except that the resin composition (pellets) for forming the polycarbonate resin layer used in the polycarbonate resin layer was changed to (C-3).

[0084] Furthermore, a thermosetting polyurethane adhesive (manufactured by Toyo Morton Co., Ltd., main component: BHS-6020A, curing agent: BHS-6020C, solid content concentration: 30% by mass) was applied to one side of a polarizing film prepared by the same process as in Example 8. Then, the film was bonded to the hard coat surface on the polycarbonate resin layer side of the multilayer obtained earlier, with the stretch axis aligned, to obtain a one-sided laminated product. Next, the thermosetting polyurethane adhesive was applied to the unbonded side of the one-sided laminated product, and a polycarbonate film (manufactured by Mitsubishi Gas Chemical Co., Ltd., S-2000, thickness: 200 μm, flame retardant-free) was bonded with the stretch axis aligned. A laminator (manufactured by MCK Co., Ltd., MP-630A) was used for bonding, with the laminator roll set to 60°C, the roll rotation speed to 1.5 m / min, and the bonding pressure to 0.5 MPa. The obtained multilayer was evaluated for FMVSS testing and pencil hardness in the same manner as in Example 1.

[0085] Example 11 (c) A multilayer was obtained in the same manner as in Example 1, except that the resin composition (pellets) for forming the polycarbonate resin layer used in the polycarbonate resin layer was changed to (C-3).

[0086] Furthermore, a thermosetting polyurethane adhesive (manufactured by Toyo Morton Co., Ltd., main component: BHS-6020A, curing agent: BHS-6020C, solid content concentration: 30% by mass) was applied to one side of a polarizing film prepared by the same process as in Example 8. Then, the film was bonded to the PC-side hard coat surface of the resulting multilayer with the stretch axis aligned to obtain a one-sided laminated product. Next, the thermosetting polyurethane adhesive was applied to the unbonded side of the one-sided laminated product, and a 200 μm polycarbonate film was bonded to it with the stretch axis aligned. The polycarbonate film used was the base material 2 consisting only of the polycarbonate resin layer described above (c). A laminator (manufactured by MCK Co., Ltd., MP-630A) was used for bonding, with the laminator roll set to 60°C, the roll rotation speed to 1.5 m / min, and the bonding pressure to 0.5 MPa. The obtained multilayer was evaluated for FMVSS testing and pencil hardness in the same manner as in Example 1.

[0087]

[0088]

[0089]

[0090] In Tables 3 to 5 above, the thickness of the acrylic resin layer of the substrate (μm) refers to (b) the thickness of the thermoplastic acrylic resin layer. In Tables 3 to 5 above, PMMA-side HC refers to (b) the type of hard coat layer forming composition applied to the surface of the thermoplastic acrylic resin layer. In Tables 3 to 5 above, PC-side HC refers to (c) the type of hard coat layer forming composition applied to the surface of the polycarbonate resin layer.

[0091] As is clear from the above results, the multilayer material of the present invention had high surface hardness and excellent flame retardancy (Examples 1 to 11). When the hard coat layer did not contain inorganic particles (Comparative Example 1), both surface hardness and flame retardancy were inferior. (b) When the thickness of the thermoplastic acrylic resin layer was thin (Comparative Example 2), the surface hardness was low. When the hard coat layer was not provided on both sides (Comparative Example 3), the flame retardancy was poor. (b) When the thickness of the thermoplastic acrylic resin layer was thicker than 80 μm (Comparative Example 4), the flame retardancy was poor. Furthermore, as shown in Examples 8 to 11, a good multilayer material was obtained even when a polarizing film was laminated, and it was confirmed that it is preferably used as a dust cover for a head-up display.

[0092] Although the present invention has been described in detail using specific embodiments, it will be apparent to those skilled in the art that various modifications are possible without departing from the intent and scope of the invention.

[0093] 1. Multilayer structure 2. (a) (meth)acrylate-based hard coat layer 3. (b) Thermoplastic acrylic resin layer 4. (c) Polycarbonate resin layer 5. (d) (meth)acrylate-based hard coat layer

Claims

1. A multilayer body having (a) a (meth)acrylate hard coat layer, (b) a thermoplastic acrylic resin layer, (c) a polycarbonate resin layer, and (d) a (meth)acrylate hard coat layer in this order, wherein the (a) (meth)acrylate hard coat layer and the (d) (meth)acrylate hard coat layer each independently contain inorganic particles in a proportion of 20 to 80% by mass, and the thickness of the (b) thermoplastic acrylic resin layer is 15 to 80 μm.

2. Particle size (D) of the inorganic particles ５０ The multilayer according to claim 1, wherein the average of the ) is less than 120 nm.

3. The multilayer body according to claim 1 or 2, wherein the pencil hardness of the multilayer body at a 500g load measured from the (meth)acrylate-based hard coat layer side is H or higher.

4. The multilayer according to claim 1 or 2, wherein the (d) (meth)acrylate-based hard coat layer contains a component derived from a polyfunctional urethane (meth)acrylate.

5. The multilayer according to claim 1 or 2, wherein the flame retardant content in the (c) polycarbonate resin layer is less than 0.01% by mass.

6. The multilayer according to claim 1 or 2, wherein the flame retardant content in the (c) polycarbonate resin layer is 0.01% by mass or more and less than 0.1% by mass.

7. The multilayer body according to claim 1 or 2, further comprising an anti-reflective layer.

8. The multilayer according to claim 1 or 2, further comprising a polarizing layer.

9. A dust cover for a head-up display, comprising a multilayer body according to any one of claims 1 to 8.

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