Multilayer dust cover for head-up display

Abstract

The invention provides a multilayer body and a dust cover for a head-up display using the multilayer body. Wherein the multilayer body has a substrate layer and an infrared ray absorbing layer, the infrared ray absorbing layer contains an ultraviolet curable resin, two or more colorants, and a photopolymerization initiator, and the colorants contain a tungsten oxide and a dye.

Description

Technical Field

[0001] This invention relates to a multilayer dust cover for head-up displays. In particular, it relates to a multilayer comprising a polycarbonate resin layer and an acrylic resin layer. Background Technology

[0002] In addition to its excellent transparency, polycarbonate resin also has superior processability and impact resistance compared to glass. Furthermore, compared to other plastic materials, there is no need to worry about toxic gases. Therefore, it is widely used in various fields and is also used as a thermoforming material for vacuum forming and air compression forming.

[0003] On the other hand, because polycarbonate resin typically has low surface hardness, molded products made from polycarbonate resin are often easily scratched. Therefore, research has been conducted on techniques that, when polycarbonate resin is formed into a film, form a layer containing acrylic resin or an infrared absorbing layer (protective layer) on the surface to prevent scratches on the product surface. Such multilayers are described in Patent Documents 1 and 2.

[0004] Existing technical documents Patent documents Patent Document 1: International Publication No. 2016 / 060100 Patent Document 2: International Publication No. 2021 / 215435 Summary of the Invention

[0005] The problem that the invention aims to solve Therefore, tungsten oxide is typically incorporated into the infrared absorbing layer as described above to suppress near-infrared transmission. However, the projected image of a multilayer with tungsten oxide incorporated sometimes appears bluish. Ideally, the projected image of a multilayer is a black and white projection image.

[0006] The purpose of this invention is to solve related problems and provide a multilayer body that produces projection images without blue tint, has high transparency and low infrared transmittance, as well as a dust cover for a head-up display using the multilayer body.

[0007] Technical solutions for solving the problem After conducting research on the above-mentioned issues, the inventors of this invention discovered that by combining tungsten oxide with dye in the infrared absorption layer, the above-mentioned issues can be solved.

[0008] Specifically, the above-mentioned problems were solved through the following solution.

[0009] <1> A multilayer having a substrate layer and an infrared absorbing layer, The aforementioned infrared absorbing layer comprises an ultraviolet-curable resin, two or more colorants, and a photopolymerization initiator. The aforementioned colorant comprises tungsten oxide and dye.

[0010] <2> according to <1> The multilayer body, wherein the absolute values ​​of a* and b* values ​​in the L*a*b* color system of the multilayer body are each independently less than 2.0.

[0011] <3> according to <1> or <2> The multilayer body, wherein when the full-spectrum transmittance T of the multilayer body is 81% or higher, the ratio T / T1 to the transmittance T1 at a wavelength of 1000 nm is 1.5 or higher; and when the full-spectrum transmittance T is less than 81%, the ratio T / T1 is 2 or higher.

[0012] <4> according to <1> ~ <3> In any one of the multilayers, the substrate layer comprises an acrylic resin layer and a polycarbonate resin layer, and the infrared absorbing layer is located on the side of the polycarbonate resin layer opposite to the acrylic resin layer.

[0013] <5> according to <4> The multilayer body wherein the content of sulfonate metal salt in at least one of the acrylic resin layer and the polycarbonate resin layer is 0.01 to 0.80 by mass.

[0014] <6> according to <4> The multilayer body, wherein the content of sulfonate metal salt in the polycarbonate resin layer is 0.01 to 0.80 by mass.

[0015] <7> according to <1> ~ <6> The multilayer body described in any one of the following statements has a haze value of less than 2.0% as measured according to JIS K 7136.

[0016] <8> according to <1> ~ <7> The multilayer body according to any one of the following methods, wherein the infrared absorbing layer contains 20% by mass or more of the tungsten oxide described above.

[0017] <9> according to <1> ~ <8> In any one of the multilayer bodies, the infrared absorbing layer contains 0.5 to 6% by mass of a red colorant and a yellow colorant, respectively.

[0018] <10> according to <1> ~ <9> In any one of the multilayer bodies, the infrared absorbing layer contains 0.5 to 6% by mass of red dye and yellow dye, respectively.

[0019] <11> according to <1> ~ <10> The multilayer body according to any one of the following methods, wherein the multilayer body further comprises a hard coating layer, wherein the hard coating layer is stacked in the order of infrared absorbing layer, polycarbonate resin layer, acrylic resin layer and hard coating layer.

[0020] <12> according to <11> The multilayer body, wherein the hard coating contains inorganic particles.

[0021] <13> according to <1> ~ <12> The multilayer body according to any one of the following methods, wherein the multilayer body further comprises an anti-reflective layer.

[0022] <14> according to <1> ~ <13> The multilayer body according to any one of the following methods, wherein the multilayer body further comprises a polarizing layer.

[0023] <15> A dust cover for a head-up display, wherein the dust cover for a head-up display includes <1> ~ <14> The multilayer body as described in any one of the following.

[0024] Invention Effects According to the present invention, it is possible to provide a multilayer body that has a non-blue-tinted projected image, high transparency, and low infrared transmittance, as well as a dust cover for a head-up display using the multilayer body. Attached Figure Description

[0025] Figure 1 This is a cross-sectional schematic diagram illustrating an example of the multilayer body of the present invention. Detailed Implementation

[0026] The following will describe in detail specific embodiments for implementing the present invention (hereinafter referred to as "this embodiment"). It should be noted that the following embodiments are merely illustrative examples for illustrating the present invention, and the present invention is not limited to these embodiments.

[0027] It should be noted that in this specification, "~" is used to indicate the lower and upper limits, including the values ​​recorded before and after it.

[0028] Unless otherwise stated, all property values ​​and characteristic values ​​in this specification refer to values ​​at 23°C.

[0029] In this specification, unless otherwise stated, the weight-average molecular weight and number-average molecular weight are polystyrene equivalent values ​​determined by GPC (gel permeation chromatography).

[0030] In this specification, "(meth)acrylate" means either or both of acrylate and methacrylate.

[0031] In this specification, "multilayer body" means that it includes articles that form the shape of a film or sheet. "Film" and "sheet" refer to molded articles that are thin relative to their length and width, and are generally flat. Furthermore, "film" and "sheet" in this specification can be single-layered or multi-layered.

[0032] Where the measurement methods described in accordance with the standards given in this instruction manual vary from year to year, the standards based on the date of January 1, 2022 shall be used unless otherwise stated.

[0033] The accompanying diagrams are schematic diagrams, and the scale may differ from the actual figures.

[0034] In this specification, near-infrared light refers to light with a wavelength of 700nm to 2500nm.

[0035] The multilayer body of this embodiment has a substrate layer and an infrared absorbing layer. The multilayer body is characterized in that the infrared absorbing layer contains an ultraviolet-curable resin, two or more colorants and a photopolymerization initiator, and the colorants contain tungsten oxide and dye.

[0036] This configuration allows for the production of multilayer bodies with non-blue-tinted projected images, high transparency, and low infrared transmittance.

[0037] To reduce the near-infrared transmittance of multilayers, doping the infrared absorption layer with tungsten oxide can be considered. However, the projected image of a multilayer doped with tungsten oxide tends to be bluish, while the ideal projected image is black and white. Therefore, it has been considered to combine tungsten oxide with other colorants to adjust it to be overall darker. However, after research, the inventors of this invention found that while combining pigments as colorants can adjust the hue of the projected image, it ultimately leads to poor transparency. The inventors deduced that this is a problem caused by poor pigment dispersion. In this embodiment, at least one dye is used as a colorant, thereby solving the above-mentioned problem.

[0038] The following describes the details of the present invention.

[0039] <Infrared Absorption Layer> The infrared absorption layer in this embodiment comprises an ultraviolet-curable resin, two or more colorants, and a photopolymerization initiator. The colorants include tungsten oxide and a dye. By including tungsten oxide and a dye, the overall color is adjusted to be predominantly black, thereby enabling the formation of a black-and-white projection image. Furthermore, by incorporating a dye as a colorant, the dispersibility of the dye in the composition for forming the infrared absorption layer can be improved, thereby increasing transparency. For example, when the multilayer body is in a black tone, the absolute values ​​of the a* and b* values ​​in the L*a*b* color system of the multilayer body are each independently 2.0 or less.

[0040] <<UV-curable resins>> The type of UV-curable resin used in this embodiment is not particularly limited, and known resins can be used.

[0041] Examples of UV-curable resins include polymers containing (meth)acryloyl groups and polyfunctional urethane (meth)acrylate oligomers, with polyfunctional urethane (meth)acrylate oligomers being preferred.

[0042] Polymers containing (meth)acryloyl groups can be synthesized, for example, by copolymerizing (meth)acrylic acid and glycidyl ether of (meth)acrylic acid to form an epoxy compound with a (meth)acrylate backbone, and then adding acrylic acid or methacrylic acid to it. Synthetic examples are shown below. Examples of epoxy (meth)acrylates used as polymers containing (meth)acryloyl groups include compounds having repeating units as shown in formula (I). In formula (I), m is an alkylene group or a single bond with 1 to 4 carbon atoms, n is an alkyl group or a hydrogen atom with 1 to 4 carbon atoms, p is a single bond or an alkylene group with 1 or 2 carbon atoms, and q is an alkyl group or a hydrogen atom with a total number of 1 to 12 carbon atoms that may contain at least one of the substituents of epoxy, hydroxyl, acryloyl and methacryloyl.

[0043] The epoxy (meth)acrylate polymer more preferably comprises the following repeating unit, namely, in the above formula (I), m is an alkylene group with 1 or 2 carbon atoms, n is an alkyl group with 1 or 2 carbon atoms, p is a single bond or methylene group, and q is a repeating unit with a total number of 1 to 6 alkyl or hydrogen atoms that may contain at least one of the substituents of glycidyl group, hydroxyl group and acryloyl group.

[0044] For example, in the above formula (I), m is methylene, n is methyl, p is a single bond, q is methyl, alkyl with 5 or fewer carbon atoms containing glycidyl (epoxy) group, alkyl with 8 or fewer carbon atoms containing hydroxyl and acryloyl group, etc.

[0045] Specific examples of repeating units contained in epoxy (meth)acrylate polymers include repeating units shown in formulas (II-a), (II-b), and (II-c). In the (meth)acrylate polymer, based on the total molar number of repeating units of formula (II-a), formula (II-b), and formula (II-c), the proportion of repeating units of formula (II-a) is preferably 30-85 mol%, more preferably 40-80 mol%. The proportion of repeating units of formula (II-b) is preferably 5-30 mol%, more preferably 10-25 mol%, based on the total molar number described above. Furthermore, the proportion of repeating units of formula (II-c) is preferably 10-40 mol%, more preferably 10-35 mol%, based on the total molar number described above.

[0046] Furthermore, the molar ratio of the repeating unit in formula (II-a), the repeating unit in formula (II-b), and the repeating unit in formula (II-c) is preferably 4.5 to 5.5: 1.5 to 2.5: 2.5 to 3.5, for example, 5: 2: 3.

[0047] These polymers containing (meth)acryloyl groups are commercially available and readily available. Examples include SMP-220A (manufactured by Kyoeisha Chemical Co., Ltd.), SMP-250A (manufactured by Kyoeisha Chemical Co., Ltd.), SMP-360A (manufactured by Kyoeisha Chemical Co., Ltd.), SMP-550A (manufactured by Kyoeisha Chemical Co., Ltd.), HA7975 (manufactured by Showa Denko Materials Co., Ltd.), HA7975D (manufactured by Showa Denko Materials Co., Ltd.), RA-4101 (manufactured by Neage Kogyo Co., Ltd.), 8KX-078 (manufactured by Taisei Fine Chemicals Co., Ltd.), and 8KX-212 (manufactured by Taisei Fine Chemicals Co., Ltd.).

[0048] Examples of polyfunctional urethane (meth)acrylate oligomers include the urethane esterification reaction products of (meth)acrylate monomers having at least one (meth)acryloyloxy and one hydroxyl group in one molecule with polyisocyanates; and the urethane esterification reaction products of isocyanate compounds obtained by reacting polyols and polyisocyanates with (meth)acrylate monomers having at least one or more (meth)acryloyloxy and one or more hydroxyl groups in one molecule.

[0049] Examples of (meth)acrylate monomers used in carbamate reactions that have at least one (meth)acryloyloxy and one hydroxyl group in one molecule include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, glyceryl di(meth)acrylate, trimethylolpropane di(meth)acrylate, pentaerythritol tri(meth)acrylate, and pentaerythritol penta(meth)acrylate.

[0050] Examples of polyisocyanates used in carbamate reactions include hexamethylene diisocyanate, lysine diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, toluene diisocyanate, phenyl diisocyanate, diisocyanates obtained by hydrogenation of aromatic isocyanates (e.g., hydrogenated toluene diisocyanate, hydrogenated phenyl diisocyanate, etc.), triphenylmethane triisocyanate, dimethylene triphenyl triisocyanate, etc., or polyisocyanates obtained by polymerizing diisocyanates.

[0051] Polyols used in urethane esterification reactions typically include, in addition to aromatic, aliphatic, and alicyclic polyols, polyester polyols and polyether polyols. Examples of aliphatic and alicyclic polyols include 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, ethylene glycol, propylene glycol, trimethylolethane, trimethylolpropane, dimethylolheptane, dimethylolpropionic acid, dimethylolbutyric acid, glycerol, and hydrogenated bisphenol A.

[0052] Examples of polyester polyols include products obtained through the dehydration condensation reaction of the aforementioned polyols with polycarboxylic acids. Specific compounds of polycarboxylic acids include succinic acid, adipic acid, maleic acid, trimellitic acid, hexahydrophthalic acid, phthalic acid, isophthalic acid, and terephthalic acid. These polycarboxylic acids can also be acid anhydrides. Furthermore, in addition to polyalkylene glycols, examples of polyether polyols include polyoxyalkylene modified polyols obtained by reacting the aforementioned polyols or phenols with epoxides.

[0053] Furthermore, multifunctional polyester (meth)acrylate oligomers are obtained through a dehydration condensation reaction of (meth)acrylic acid, polycarboxylic acids, and polyols. Examples of polycarboxylic acids used in the dehydration condensation reaction include succinic acid, adipic acid, maleic acid, itaconic acid, trimellitic acid, pyromellitic acid, hexahydrophthalic acid, phthalic acid, isophthalic acid, and terephthalic acid. These polycarboxylic acids can also be acid anhydrides. Examples of polyols used in the dehydration condensation reaction include 1,4-butanediol, 1,6-hexanediol, diethylene glycol, triethylene glycol, propylene glycol, neopentyl glycol, dimethylolheptan, dimethylolpropionic acid, dimethylolbutyric acid, trimethylolpropane, bis(trimethylolpropane), pentaerythritol, and dipentaerythritol.

[0054] Multifunctional epoxy (meth)acrylate oligomers are obtained by the addition reaction of polyglycidyl ethers with (meth)acrylic acid. Examples of polyglycidyl ethers include ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, and bisphenol A diglycidyl ether.

[0055] As polyfunctional urethane (meth)acrylates, commercially available products can also be used. Examples include UN-3320HA, UN-3320HC, UN-906S, UN-901T, UN-952, UN-904, UN-905, UN-3320HS, H-575 (all manufactured by Negami Kogyo Co., Ltd.), U-6LPA, UA-1100H (all manufactured by Shin-Nakamura Chemical Co., Ltd.), EBECRYL5129, EBECRYL4738, EBECRYL4740, EBECRYL4513, EBECRYL8254, EBECRYL220, and EBECRYL8701 (all manufactured by Daicel Allnex Co., Ltd.).

[0056] The double bond equivalent of the UV-curable resin is 400 g / mol or less, preferably 360 g / mol or less, and more preferably 250 g / mol or less. Setting the value above or above this lower limit often improves the hardness of the resulting infrared absorption layer. As a lower limit, 100 g / mol or more is preferred.

[0057] The number of functional groups in the UV-curable resin is preferably 2 to 10, more preferably 3 to 7.

[0058] The weight-average molecular weight of the UV-curable resin is preferably 1,000 to 100,000, more preferably 1,000 to 50,000, and even more preferably 1,000 to 30,000. Setting it above 1,000 can more effectively suppress curing shrinkage; setting it below 100,000 can make coating easier.

[0059] In addition to the above, UV-curable resins may also contain monofunctional (meth)acrylate alkyl ester monomers and / or polyfunctional (meth)acrylate alkyl ester monomers. Furthermore, they may contain styrene monomers, styrene oligomers, cyclic anhydrides, N-substituted maleimide compounds, and lactone ring compounds, etc.

[0060] In this embodiment, the content of the ultraviolet-curable resin contained in the infrared absorption layer is preferably 50% by mass or more, more preferably 55% by mass or more, and preferably 80% by mass or less, more preferably 75% by mass or less, and even more preferably 70% by mass or less. By setting the content above the above lower limit, multilayers with higher toughness and higher hardness can often be obtained. Furthermore, by setting the content below the above upper limit, a coating film with a good balance between light transmittance and infrared absorption can be obtained.

[0061] The infrared absorbing layer of this embodiment may contain only one type of ultraviolet-curable resin, or it may contain two or more types. When it contains two or more types, the total amount is preferably within the above-mentioned range.

[0062] <<Two or more colorants>> The infrared absorption layer of this embodiment contains two or more colorants, including tungsten oxide and dye.

[0063] The colorant used in this embodiment includes tungsten oxide. By including tungsten oxide, the multilayer can block near-infrared light, thus making it more suitable for use as a dust cover for head-up displays.

[0064] Cesium tungsten oxide (CWO) is preferred as the tungsten oxide.

[0065] In this embodiment, the tungsten oxide content in the infrared absorption layer is preferably 20% by mass or more, more preferably 25% by mass or more, further preferably 28% by mass or more, even more preferably 31% by mass or more, and preferably 50% by mass or less, more preferably 45% by mass or less. By setting it above the above lower limit, the infrared absorption effect can often be further improved. By setting it below the above upper limit, excellent transparency can be maintained.

[0066] The infrared absorbing layer of this embodiment may contain only one type of tungsten oxide, or it may contain two or more types. When it contains two or more types, the total amount is preferably within the above-mentioned range.

[0067] The colorant used in this embodiment includes dyes. The dyes of this invention refer to colorants that are soluble in at least one solvent at a temperature of 23°C, including products sold at least as solvents.

[0068] In this embodiment, the colorant preferably comprises solvent yellow and / or solvent red.

[0069] The colorant used in this invention preferably includes, in addition to tungsten oxide, at least one of a red colorant and a yellow colorant. With this configuration, a colorant with a black hue can be formed.

[0070] At least one of the colorants used in this embodiment is a dye.

[0071] Specifically, the dye is preferably a red dye and / or a yellow dye, more preferably containing both a red dye and a yellow dye.

[0072] In this embodiment, the content of the red colorant (preferably a red dye) in the infrared absorption layer is preferably 0.5% by mass or more, more preferably 1% by mass or more, and preferably 6% by mass or less, more preferably 5% by mass or less, further preferably 3% by mass or less, and most preferably 2% by mass or less. By setting the content above the lower limit, the coloration of the projected image can be more effectively suppressed. By setting the content below the upper limit, excellent transparency can be maintained.

[0073] In this embodiment, the content of the yellow colorant (preferably a yellow dye) in the infrared absorption layer is preferably 0.5% by mass or more, more preferably 1% by mass or more, and preferably 6% by mass or less, more preferably 5% by mass or less, and even more preferably 3% by mass or less. By setting it above the above lower limit, the coloration of the projected image can be more effectively suppressed. By setting it below the above upper limit, excellent transparency can be maintained.

[0074] Preferably, the amount and ratio of the red and yellow colorants are adjusted so that the infrared absorption layer meets the required transmittance at a wavelength of 1000 nm and the ratio of the full-spectrum transmittance T to the transmittance T1 at a wavelength of 1000 nm is T / T1.

[0075] In this embodiment, the content of the colorant other than tungsten oxide in the infrared absorption layer is preferably 0.5% by mass or more, more preferably 1% by mass or more, and preferably 5% by mass or less, more preferably 3% by mass or less. By setting it above the lower limit, the coloration of the projected image can be more effectively suppressed. By setting it below the upper limit, excellent transparency can be maintained.

[0076] The infrared absorption layer of this embodiment may contain only one dye or two or more dyes. When containing two or more dyes, it is preferable that the total amount is within the above-mentioned range.

[0077] The infrared absorbing layer of this embodiment may also contain pigments other than tungsten oxide. Examples include red pigments and / or yellow pigments. In this embodiment, when the infrared absorbing layer contains pigments other than tungsten oxide, it is preferable to include a combination of red pigment and yellow dye and / or a combination of yellow pigment and red dye.

[0078] In this embodiment, when the infrared absorbing layer contains pigments other than tungsten oxide, the total content of the pigments other than tungsten oxide in the infrared absorbing layer is preferably 0.1% by mass or more, more preferably 1.0% by mass or more, and preferably 7% by mass or less, more preferably 5% by mass or less. By setting the content above the lower limit, the coloration of the projected image can be more effectively suppressed. By setting the content below the upper limit, excellent transparency can be maintained.

[0079] The infrared absorbing layer in this embodiment is preferably substantially free of pigments other than tungsten oxide. "Substantially free" means that the content of pigments other than tungsten oxide in the infrared absorbing layer is preferably less than 10% by mass of the tungsten oxide content, more preferably less than 5% by mass, and even more preferably less than 1% by mass.

[0080] <<Photopolymerization Initiators>> The photopolymerization initiator used in this embodiment can be any known photopolymerization initiator, as long as it can cure the UV-curable resin.

[0081] As a photopolymerization initiator, a photoradical initiator that can break bonds and generate free radicals under the action of visible light or ultraviolet light with a wavelength shorter than 450 nm is preferred. Examples include photopolymerization initiators having an acylphosphine oxide skeleton, an α-hydroxy ketone skeleton, a benzyl dimethyl ketal skeleton, an amino ketone skeleton, a benzophenone skeleton, or a triazine skeleton containing trichloromethyl. Photopolymerization initiators having an acylphosphine oxide skeleton and / or an α-hydroxy ketone skeleton are preferred.

[0082] Specific examples of photopolymerization initiators include benzophenone, thioxanone, benzyl dimethyl ketal, α-hydroxy ketone, α-hydroxyalkyl phenyl ketone, α-amino ketone, α-aminoalkyl phenyl ketone, monoacylphosphine oxide, diacylphosphine oxide, hydroxybenzophenone, aminobenzophenone, dicene, oxime ester, and oxyphenyl acetate.

[0083] In addition to the examples mentioned above, as polymerization initiators, references can also be made to the descriptions in International Publication No. 2023 / 095664, paragraph

[0039] ; International Publication No. 2022 / 102736, paragraphs

[0234] to

[0238] ; Japanese Patent Application Publication No. 2010-106268, paragraphs

[0135] onwards; Japanese Patent Application Publication No. 2009-13115, paragraphs

[0018] to

[0025] ; and Japanese Patent Application Publication No. 2005-154312, paragraphs

[0018] to

[0025] , the contents of which are incorporated herein by reference.

[0084] The content of the photopolymerization initiator contained in the infrared absorption layer of this embodiment is preferably 0.1% by mass or more, more preferably 1% by mass or more, even more preferably 1.2% by mass or more, and preferably 10% by mass or less, more preferably 7% by mass or less, even more preferably 4% by mass or less. By setting it above the above lower limit value, sufficient curability can be exhibited. By setting it below the above upper limit value, storage stability and aging degradation can often be further improved.

[0085] The infrared absorbing layer of this embodiment may contain only one photopolymerization initiator, or it may contain two or more. When it contains two or more, the total amount is preferably within the above-mentioned range.

[0086] The infrared absorbing layer of this embodiment may contain a heat stabilizer. The content of the heat stabilizer in the infrared absorbing layer is preferably 0.1 to 20.0% by mass, more preferably 2 to 10.0% by mass. The heat stabilizer may contain only one type or two or more types. When two or more types are contained, the total amount is preferably within the above range. By setting the content above the lower limit, deterioration of the infrared absorbing layer during damp heat testing can be prevented.

[0087] <<Other Ingredients>> In addition to the components mentioned above, the infrared absorbing layer may also contain leveling agents, ultraviolet absorbers, light stabilizers, flame retardants, flame retardant additives, colorants, antistatic agents, fluorescent whitening agents, antifogging agents, flow improvers, plasticizers, dispersants, antibacterial agents, anti-blocking agents, impact resistance improvers, slip resistance improvers, color improvers, acid scavengers, etc. One or more of these components may be used.

[0088] The total amount of these other components in the infrared absorption layer is preferably 0% or more and less than 10% by mass, more preferably 0% or more and less than 5% by mass, or may be 0% or more and less than 1% by mass.

[0089] <<Light Stabilizers>> As light stabilizers, hindered amine light stabilizers such as bis(1,2,2,6,6-pentamethyl-4-piperidinyl) sebacate, bis(2,2,6,6-tetramethylpiperidin-4-yl) sebacate, bis(1-undecalkoxy-2,2,6,6-tetramethylpiperidin-4-yl) carbonate, 1,2,2,6,6-13-pentamethyl-4-piperidinyl methacrylate, 2,2,6,6-tetramethyl-4-piperidinyl methacrylate, bis[2,2,6,6-tetramethyl-1-(octoxy)piperidin-4-yl] sebacate, and 2-[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]-2-butylmalonic acid bis[1,2,2,6,6-pentamethyl-4-piperidinyl] ester can be used.

[0090] The content ratio of light stabilizer in the infrared absorption layer is preferably 0-5% by mass, more preferably 0-3% by mass, and even more preferably 0-1% by mass. By setting it below the above upper limit, the UV-curable resin can often be cured more effectively.

[0091] Examples of flame retardants include halogen-based flame retardants and phosphorus-based flame retardants. Examples of phosphorus-based flame retardants include aromatic phosphate compounds, phenanthrene phosphate compounds, phosphonate metal salts, ammonium polyphosphate, melamine polyphosphate, phosphate ester amides, and red phosphorus. For further information on flame retardants, please refer to paragraphs

[0054] to

[0082] of Japanese Patent Application Publication No. 2022-104214 and paragraphs

[0052] to

[0077] of Japanese Patent Publication No. 7021724, the contents of which are incorporated herein by reference.

[0092] In the infrared absorption layer, the total amount of ultraviolet-curable resin, photopolymerization initiator and colorant preferably accounts for more than 90% by mass, more preferably more than 95% by mass, and even more preferably more than 97% by mass.

[0093] In addition, the total amount of UV-curable resin, photopolymerization initiator and colorant in the infrared absorption layer will not exceed 100% by mass.

[0094] The thickness of the infrared absorption layer is preferably 0.5 μm or more, more preferably 1 μm or more, even more preferably 1.5 μm or more, and preferably 10 μm or less, more preferably 8 μm or less, even more preferably 5 μm or less. By setting it below the above upper limit value, curing defects will not occur during UV curing. By setting it above the above lower limit value, the effect as an infrared absorption layer can be more effectively demonstrated.

[0095] <Layer Composition of Multi-layer Structures> Next, the layer structure of the multilayer body in this embodiment will be described.

[0096] The multilayer of this embodiment has a substrate layer and an infrared absorbing layer. The substrate layer preferably comprises an acrylic resin layer and a polycarbonate resin layer, more preferably comprising both an acrylic resin layer and a polycarbonate resin layer, and the infrared absorbing layer is located on the side of the polycarbonate resin layer opposite to the acrylic resin layer. By adopting this configuration, the multilayer can exhibit superior weather resistance.

[0097] The following is for reference Figure 1 This section describes a preferred example of a multilayer structure in this embodiment. It goes without saying that the multilayer structure in this embodiment is not limited to... Figure 1 The method described above.

[0098] Figure 1 This is a cross-sectional schematic diagram illustrating an example of the multilayer structure of this embodiment. 1 represents the multilayer structure, 2 represents the acrylic resin layer, 3 represents the polycarbonate resin layer, and 4 represents the infrared absorbing layer. In the multilayer structure 1 of this embodiment, the infrared absorbing layer 4 is located on the side of the polycarbonate resin layer 3 opposite to the acrylic resin layer 2. This configuration improves the weather resistance of the multilayer structure. It should be noted that in this specification, the acrylic resin layer 2 and the polycarbonate resin layer 3 are sometimes referred to together as the substrate. Furthermore, it is self-evident that the substrate may also include other layers without departing from the spirit of the invention. Details of these other layers will be described later.

[0099] The infrared absorption layer 4 can be the outermost layer of the multilayer 1. By providing the infrared absorption layer 4, the surface hardness of the multilayer 1 can often be further improved. In the multilayer 1 of this embodiment, it is preferable to stack the acrylic resin layer 2, the polycarbonate resin layer 3, and the infrared absorption layer 4 in that order, with the infrared absorption layer 4 located on the surface of the polycarbonate resin layer 3. By having the infrared absorption layer 2 located on the surface of the polycarbonate resin layer 3, the formability of the infrared absorption layer 2 (the coatability of the composition for forming the infrared absorption layer) can be further improved. As long as the multilayer of this embodiment stacks the acrylic resin layer 2, the polycarbonate resin layer 3, and the infrared absorption layer 4 in the above order, other layers may be present without departing from the spirit of this embodiment, but it is preferable that there are no other layers, that is, the above three layers are adjacent to each other.

[0100] Furthermore, the multilayer in this embodiment can be a flame-retardant substrate in which at least one of the acrylic resin layer and the polycarbonate resin layer contains 0.01 to 0.80% by mass of a sulfonate metal salt. By using such a flame-retardant substrate, it can also be applied to applications requiring flame retardancy. These details will be explained later.

[0101] The thickness (total thickness) of the multilayer is preferably, but not particularly limited to, 30 μm or more, more preferably 100 μm or more. In addition, the thickness of the multilayer is preferably 10,000 μm or less, more preferably 5,000 μm or less, and even more preferably 2,000 μm or less, and can be 1,000 μm or less or 500 μm or less.

[0102] The multilayer structure in this embodiment preferably exhibits excellent infrared shielding performance.

[0103] Specifically, the transmittance of the multilayer at a wavelength of 1000 nm in this embodiment is preferably 60% or less, more preferably 40% or less, further preferably 20% or less, and even more preferably 15% or less. Although no specific lower limit is specified, it is actually greater than 0%.

[0104] The multilayer in this embodiment is preferably highly transparent.

[0105] Specifically, it is even more preferable that the haze of the multilayer body, as measured according to JIS K7136, is 3% or less, more preferably 2% or less, further preferably 1.5% or less, and even more preferably 1% or less. Although the lower limit is preferably 0% or more, in practice it exceeds 0%.

[0106] In this embodiment, the multilayer body preferably has a ratio of T / T1 of 81% full-spectrum transmittance T to 1000nm transmittance T1 of 1.5 or more, and preferably 20 or less, more preferably 4 or less, further preferably 3.5 or less, even more preferably 3 or less, and still more preferably 2 or less, and preferably 1.5 or more.

[0107] Furthermore, in this embodiment, the multilayer body preferably has a ratio T / T1 of 2 or more when the full-spectrum transmittance T is less than 81%, and more preferably 30 or less, and more preferably 25 or less. By adopting such a configuration, the performance required for a head-up display can be met.

[0108] In this embodiment, the a* and b* values ​​of the multilayer body in the L*a*b* color system are preferably close to 0. Specifically, it is preferable that the absolute values ​​of the a* and b* values ​​of the multilayer body in the L*a*b* color system are each independently 2.0 or less, more preferably 1.9 or less, even more preferably 1.8 or less, even more preferably 1.6 or less, and even more preferably 1.0 or less, and preferably 0. Even 0.001 or more is sufficient to meet the required performance.

[0109] The multilayer body of this embodiment may also have flame retardancy. Specifically, the multilayer body preferably meets the Class C rating in the flammability test (FMVSS test) based on FMVSS No. 302 (it is burning before reaching the B mark, but the burning rate is less than 102 mm / min), and more preferably meets the Class B rating in the FMVSS test (it self-extinguishes within 51 mm of the A mark (and within 60 seconds)).

[0110] The transmittance, haze, a* and b* values, and FMVSS test described above were measured according to the embodiments described later.

[0111] The multilayer structure of this embodiment preferably further includes a hard coating layer. Preferably, the hard coating layer is present on at least one side of the multilayer structure, more preferably on the side of the acrylic resin layer opposite to the polycarbonate resin layer. The hard coating layer can be the outermost surface layer of the multilayer structure. By providing a hard coating layer, the surface hardness of the multilayer structure can often be further improved. In the multilayer structure of this embodiment, the hard coating layer is preferably stacked in the order of infrared absorption layer, polycarbonate resin layer, acrylic resin layer, and hard coating layer. In the multilayer structure of this embodiment, the hard coating layer is preferably provided on the surface of the acrylic resin layer. By providing a hard coating layer on the surface of the acrylic resin layer, the coatability of the hard coating layer can be further improved.

[0112] The hard coating layer included in the multilayer of this embodiment may be a layer with a surface hardness higher than that of the polycarbonate resin layer. By including such a hard coating layer, the surface hardness of the multilayer and even the molded article can be improved.

[0113] The thickness of the hard coating is preferably 0.5 μm or more, more preferably 1 μm or more, further preferably 2 μm or more, even more preferably 2.5 μm or more, and still more preferably 3 μm or more. By setting the thickness above or below the above-mentioned lower limit, the overall pencil hardness of the multilayer body can often be further improved by using the hard coating. The upper limit of the thickness of the hard coating is preferably 20 μm or less, more preferably 15 μm or less, further preferably 12 μm or less, even more preferably 10 μm or less, and still more preferably 8 μm or less, and can be 5 μm or less. By setting the thickness below the above-mentioned upper limit, the flame retardancy can often be further improved.

[0114] The hard coating is preferably a layer obtained by applying a hard coating material that can be cured by heat curing or active energy rays and then curing it.

[0115] As an example of a coating that uses active energy rays for curing, a resin composition comprising one or more monofunctional or polyfunctional (preferably 2- to 10-functional) (meth)acrylate monomers or oligomers can be cited. A resin composition comprising monofunctional or polyfunctional (preferably 2- to 10-functional) urethane (meth)acrylate oligomers is preferred. In these resin compositions, a photopolymerization initiator is preferably added as a curing catalyst.

[0116] In addition, examples of thermosetting resin coatings include polyorganosiloxane-based and cross-linked acrylic coatings. These resin compositions are also commercially available as hard coating agents for acrylic resins or polycarbonate resin films or sheets, and can be appropriately selected based on their compatibility with the coating production line.

[0117] As a hard coating, reference can be made to the descriptions in Japanese Patent Application Publication No. 2013-020130, paragraphs

[0045] to

[0055] , Japanese Patent Application Publication No. 2018-103518, paragraphs

[0073] to

[0076] , and Japanese Patent Application Publication No. 2017-213771, paragraphs

[0062] to

[0082] , the contents of which are incorporated herein by reference.

[0118] The hard coating preferably includes, in addition to the above-mentioned components, inorganic particles, organic pigments, ultraviolet absorbers, light stabilizers, heat stabilizers, flame retardants, flame retardant additives, colorants, antistatic agents, fluorescent whitening agents, antifogging agents, flow improvers, plasticizers, dispersants, antibacterial agents, antiblocking agents, impact resistance improvers, slip resistance improvers, hue improvers, acid scavengers, etc., and more preferably, inorganic particles. One or more of these components may be used.

[0119] Examples of inorganic particles are preferably nanoparticles composed of metals and / 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 composed of two or more of these metals. Furthermore, metal compounds are preferably metal oxides, metal carbides, metal borides, metal carbonates, zeolites, clays, and their complexes, such as iron oxide, silicon dioxide, zirconium oxide, vanadium oxide, niobium oxide, tantalum oxide, chromium oxide, molybdenum oxide, tungsten oxide, cobalt oxide, nickel oxide, cerium oxide, copper oxide, zinc oxide, tin oxide, antimony oxide, titanium dioxide, aluminum oxide, indium tin oxide (ITO), cesium tungsten oxide (CWO), and mixtures thereof; silicon dioxide is more preferred.

[0120] The aforementioned inorganic particles may or may not undergo surface treatment. Surface treatment is preferred. The surface treatment agent is preferably a silane coupling agent.

[0121] The average particle size (D50) of the aforementioned inorganic particles is preferably 5 nm or more, more preferably 7 nm or more, and preferably 30 nm or less, more preferably 20 nm or less. By setting it above the aforementioned lower limit, the flame retardancy of the obtained multilayer body can often be further improved. In addition, the smaller the average particle size, the larger the ratio of surface area to mass, thereby enabling the formation of more cross-linked structures with other components.

[0122] In this embodiment, the content of inorganic particles in the hard coating is preferably 20 parts by mass or more, more preferably 25 parts by mass or more, and preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and even more preferably 35 parts by mass or less. By setting the content above the above-mentioned lower limit, the flame retardancy of the resulting multilayer can often be further improved. By setting the content below the above-mentioned upper limit, the generation of cracks in the heat resistance test of the multilayer can often be more effectively suppressed.

[0123] The aforementioned hard coating may contain only one type of inorganic particle or two or more types of inorganic particles. When containing two or more types, the total amount is preferably within the aforementioned range.

[0124] Examples of flame retardants include halogen-based flame retardants and phosphorus-based flame retardants. Examples of phosphorus-based flame retardants include aromatic phosphate compounds, phenanthrene phosphate compounds, phosphonate metal salts, ammonium polyphosphate, melamine polyphosphate, phosphate ester amides, and red phosphorus. For further information on flame retardants, please refer to paragraphs

[0054] to

[0082] of Japanese Patent Application Publication No. 2022-104214 and paragraphs

[0052] to

[0077] of Japanese Patent No. 7021724, the contents of which are incorporated herein by reference.

[0125] In addition to the above-described structure, the multilayer body of this embodiment may also have other layers. Examples include bonding layers, adhesive layers, antifouling layers, antireflective layers, and polarizing layers, with an antireflective layer being preferred.

[0126] The anti-reflective layer is typically preferably located on the side of the infrared absorbing layer opposite to the polycarbonate resin layer (e.g., Figure 1 It can be placed on the underside of 4, but it can also be placed on the polycarbonate (resin layer) side.

[0127] Details of the anti-reflective layer can be found in Japanese Patent Application Publication No. 2023-114940, paragraphs

[0062] to

[0083] , Japanese Patent Application Publication No. 2022-174051, paragraphs

[0013] to

[0041] , and Japanese Patent Application Publication No. 2021-081596, paragraphs

[0043] to

[0046] , the contents of which are incorporated herein by reference.

[0128] The polarizing layer is typically preferably located on the side of the infrared absorbing layer opposite to the polycarbonate resin layer (e.g., Figure 1 (of) 4 on the lower side.

[0129] Details of the polarizing layer can be found in Japanese Patent Application Publication No. 2008-105225, paragraphs

[0022] to

[0029] , Japanese Patent Application Publication No. 2020-52406, paragraphs

[0011] to

[0021] , and Japanese Patent Application Publication No. 2023-13533, paragraphs

[0014] to

[0037] , the contents of which are incorporated herein by reference.

[0130] Furthermore, the multilayer can also undergo one or more of the following treatments on at least one surface: fingerprint resistance treatment, anti-glare treatment, weather resistance treatment, antistatic treatment, anti-fouling treatment, and anti-blocking treatment. In addition, anti-blocking treatment refers to a treatment that allows the films to be easily peeled off even if they adhere to each other, and examples include adding anti-blocking agents and creating textures on the surface of the multilayer.

[0131] <<Polycarbonate resin layer>> The polycarbonate resin layer in this embodiment contains polycarbonate resin.

[0132] There are no particular limitations on the polycarbonate resin, and various polycarbonate resins can be used, as long as they include the -[O-R-OCO]- structural unit (R is a hydrocarbon group, such as aliphatic group, aromatic group, or both aliphatic group and aromatic group, and has a straight chain structure or a branched chain structure) in the main molecular chain. Aromatic polycarbonate resins are preferred.

[0133] In this embodiment, the polycarbonate resin preferably comprises a bisphenol-type polycarbonate resin. A bisphenol-type polycarbonate resin refers to a polycarbonate resin in which 80 mol% or more, preferably 90 mol% or more, and more preferably 95 mol% or more of the structural units constituting the polycarbonate resin are carbonate structural units derived from bisphenol and / or its derivatives. Bisphenol and / or its derivatives are preferably bisphenol A, bisphenol AP, bisphenol C, bisphenol BP, or derivatives of these bisphenols, more preferably bisphenol A, bisphenol AP, or derivatives of both, and even more preferably bisphenol A or its derivatives.

[0134] Bisphenol type polycarbonate resin is preferably bisphenol A type polycarbonate resin.

[0135] The molecular weight of polycarbonate resin is typically calculated by converting the viscosity of the solution measured at 25°C using dichloromethane as a solvent. Preferably, but not particularly limited to, it is 20,000 or more, more preferably 22,000 or more. Furthermore, the aforementioned 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 to the lower limit or above, the strength of the obtained flat molded body can be improved. Moreover, by setting the viscosity-average molecular weight to the upper limit or below, the molding and processing performance is often improved.

[0136] Wherein, viscosity-average molecular weight [Mv] refers to the intrinsic viscosity [η] (unit: dL / g) at 25°C using dichloromethane as a solvent and an Ubbelohde viscometer, based on the Schnell viscosity formula, i.e., η = 1.23 × 10⁻⁶. ﹣4 Mv 0.83 The calculated value. Furthermore, intrinsic viscosity [η] refers to the specific viscosity [η] obtained by measuring the concentration [C] (g / dL) of each solution. sp ], and the value is calculated according to the following formula. It should be noted that, in this embodiment, two or more polycarbonate resins with different viscosity-average molecular weights can be mixed and used. In this case, the viscosity-average molecular weight of the mixture is used.

[0137] The initial glass transition temperature (Tg) of the polycarbonate resin used in this embodiment is preferably 160°C or less, more preferably 155°C or less, even more preferably 154°C or less, even more preferably 153°C or less, even more preferably 152°C or less, and even more preferably 151°C or less. Furthermore, the initial glass transition temperature (Tg) of the polycarbonate resin used in this embodiment is, for example, 140°C or more, and further preferably 143°C or more, 145°C or more, 147°C or more, or 148°C or more.

[0138] The glass transition temperature was measured according to the description in paragraph

[0056] of Japanese Patent Application Publication No. 2022-080270.

[0139] Furthermore, as long as the main idea of ​​this embodiment is not deviated from, the details of the polycarbonate resin can also 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, which are incorporated herein by reference.

[0140] The content of polycarbonate resin in the polycarbonate resin layer of this embodiment is preferably 90% by mass or more, more preferably 92% by mass or more, further preferably 94% by mass or more, even more preferably 96% by mass or more, and even more preferably 97% by mass or more, and can be 98% by mass or more. The upper limit can be 100% by mass.

[0141] In this embodiment, when the polycarbonate resin layer contains two or more types of polycarbonate resin, it is preferable that their total amount is within the above-mentioned range.

[0142] The polycarbonate resin layer in this embodiment may also contain sulfonate metal salts. Sulfonate metal salts are typically used as flame retardants in polycarbonate resins.

[0143] The sulfonate metal salt is preferably an alkali metal salt. Lithium, sodium, potassium, and rubidium are preferred as the alkali metal constituting the alkali metal salt, with sodium and potassium being more preferred. Additionally, the sulfonate metal salt may also contain fluorine atoms.

[0144] The molecular weight of the sulfonate metal salt used in this embodiment is preferably 100-900, more preferably 100-500.

[0145] Specific examples of the sulfonate metal salts used in this embodiment are shown below. It goes without saying that the sulfonate metal salts used in this embodiment are not limited to these examples. The content of sulfonate metal salt in the polycarbonate resin layer is preferably 0.01 to 0.80% by mass, more preferably 0.7% by mass or less, even more preferably 0.6% by mass or less, even more preferably 0.5% by mass or less, and even more preferably 0.4% by mass or less. Depending on the application, it may be less than 0.1% by mass or less than 0.05% by mass.

[0146] The polycarbonate resin layer of this embodiment may contain only one sulfonate metal salt, or it may contain two or more sulfonate metal salts. When it contains two or more, the total amount is preferably within the above-mentioned range.

[0147] The polycarbonate resin layer in this embodiment may also contain flame retardants other than sulfonate metal salts, such as phosphorus-based flame retardants like condensed phosphate esters and phosphazenes, organosilicon-based flame retardants like polyorganosiloxanes, and halogen-based flame retardants like Br-modified polycarbonate oligomers. Specific examples of phosphorus-based flame retardants include condensed phosphate esters such as resorcinol bis(diphenyl phosphate) (RDP), resorcinol bis(xylenyl phosphate) (RDX), bisphenol A bis(diphenyl phosphate) (BDP), and biphenyl bis(diphenyl phosphate), as well as linear phenoxyphosphazenes and cyclic phenoxyphosphazenes. The content of the flame retardant in the polycarbonate resin layer is preferably 0.3 to 20% by mass, more preferably 0.5 to 10% by mass.

[0148] The polycarbonate resin layer of this embodiment may also contain ultraviolet absorbers such as triazine-based ultraviolet absorbers and benzotriazole-based ultraviolet absorbers. The content of the ultraviolet absorber in the polycarbonate resin layer is preferably 0.1 to 5.0% by mass, more preferably 0.5 to 2.0% by mass.

[0149] In addition to the components described above, the polycarbonate resin layer of this embodiment may also contain antioxidants, release agents, flame retardants, heat stabilizers, colorants, antistatic agents, fluorescent whitening agents, antifogging agents, flow improvers, plasticizers, dispersants, antibacterial agents, antiblocking agents, impact resistance improvers, slip resistance improvers, hue improvers, acid scavengers, etc. One or more of these components may be used. The preferred content of the above components, in total, is 0-5% by mass of the polycarbonate resin layer; more preferably, 0-3% by mass; further preferably, 0-1% by mass; even more preferably, 0-0.5% by mass; still more preferably, 0-0.3% by mass; and still more preferably, 0-0.1% by mass.

[0150] Examples of antioxidants include phenolic antioxidants, amine antioxidants, phosphorus-based antioxidants, and thioether antioxidants. In this embodiment, phosphorus-based antioxidants and phenolic antioxidants (more preferably hindered phenolic antioxidants), and even more preferably phosphorus-based antioxidants, are preferred.

[0151] The phosphorus-based antioxidant is preferably a phosphite antioxidant, and more preferably a phosphite compound represented by formula (1) or (2).

[0152] (1) In equation (1), R 11 and R 12 Each can be independently represented as an alkyl group with 1 to 30 carbon atoms or an aryl group with 6 to 30 carbon atoms. In equation (2), R 13 ~R17 Each can be independently represented by a hydrogen atom, an aryl group with 6 to 20 carbon atoms, or an alkyl group with 1 to 20 carbon atoms.

[0153] In the above equation (1), R 11 R 12 Each alkyl group is preferably a straight-chain or branched alkyl group having 1 to 10 carbon atoms. In R 11 R 12 When the aryl group is aryl, it is preferably represented by any one of the following formulas (1-a), (1-b), and (1-c). The "*" in the formula indicates the bonding position. In equation (1-a), R A Each of the following independently represents an alkyl group having 1 to 10 carbon atoms. In formula (1-b), R B Each can be used independently to represent an alkyl group having 1 to 10 carbon atoms.

[0154] As a hindered phenolic antioxidant, reference can be made to paragraphs

[0063] of Japanese Patent Application Publication No. 2018-090677 and

[0076] of Japanese Patent Application Publication No. 2018-188496, the contents of which are incorporated herein by reference.

[0155] In addition to the compounds mentioned above, antioxidants can be found in paragraphs

[0057] to

[0061] of Japanese Patent Application Publication No. 2017-031313, the contents of which are incorporated herein by reference.

[0156] The antioxidant content is preferably 0.001 parts by weight or more, more preferably 0.005 parts by weight or more, further preferably 0.010 parts by weight or more, and even more preferably 0.050 parts by weight or more, relative to 100 parts by weight of the polycarbonate resin layer. As for the upper limit of the antioxidant content, relative to 100 parts by weight of the polycarbonate resin layer, it is preferably 0.500 parts by weight or less, more preferably 0.300 parts by weight or less, further preferably 0.200 parts by weight or less, even more preferably 0.150 parts by weight or less, even more preferably 0.100 parts by weight or less, and particularly more preferably 0.080 parts by weight or less.

[0157] Antioxidants may be used in single or multiple forms. When using multiple forms, it is preferable that their combined amount is within the range described above.

[0158] Next, we will explain the release agents that can be included in the polycarbonate resin layer.

[0159] Types of mold release agents can be listed, but are not specifically limited to, 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.

[0160] Details of the release agent can be found in paragraphs

[0035] to

[0039] of International Publication No. 2015 / 190162, the contents of which are incorporated herein by reference.

[0161] The content of the release agent relative to 100 parts by weight of the polycarbonate resin layer is preferably 0.001 parts by weight or more, more preferably 0.005 parts by weight or more, further preferably 0.010 parts by weight or more, and even more preferably 0.050 parts by weight or more. As an upper limit, it is preferably 0.5 parts by weight or less, more preferably 0.3 parts by weight or less, and even more preferably 0.1 parts by weight or less.

[0162] A single mold release agent may be used, or two or more may be used. When using two or more, it is preferable that their total amount is within the range described above.

[0163] 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. By setting it above the above lower limit, it is not only easier to mold, but also tends to improve flame retardancy. In addition, the upper limit of the polycarbonate resin layer thickness is preferably 1000 μm or less, more preferably 750 μm or less, and even more preferably 500 μm or less.

[0164] <<Acrylic Resin Layer>> The acrylic resin layer in this embodiment contains acrylic resin.

[0165] Furthermore, the acrylic resin layer can be a single layer or multiple layers, but a single layer is preferred.

[0166] The acrylic resin layer in this embodiment comprises acrylic resin as described above.

[0167] An example of an acrylic resin is preferably a polymer in which the content of (meth)acrylate alkyl ester units (preferably alkyl methacrylate units) in all structural units is 50% by mass or more (preferably 90% by mass or more), and more preferably a polymer in which the content of (meth)acrylate methyl acrylate units (preferably methyl methacrylate units) in all structural units is 50% by mass or more (preferably 90% by mass or more). Other structural units besides (meth)acrylate alkyl ester units can be cited as examples, such as other (meth)acrylate units, styrene units, cyclic anhydride units, N-substituted maleimide units, and lactone ring units.

[0168] The acrylic resin layer may be formed solely of acrylic resin, or it may contain other thermoplastic resins in addition to acrylic resin.

[0169] As other thermoplastic resins, it is more preferable to include at least one thermoplastic resin selected from styrene-based resins, fluorinated resins such as polyvinylidene fluoride, and aromatic polyether resins such as polyphenylene ether, and even more preferably to include styrene-based resins.

[0170] An example of an acrylic resin layer is a layer in which 90% or more (preferably 95% or more, more preferably 97% or more, and even more preferably 98% or more) is formed of acrylic resin.

[0171] Another example of an acrylic resin is a layer formed of the above-mentioned acrylic resin and other thermoplastic resins (preferably styrene-based resins) comprising 90% or more by mass (preferably 95% or more by mass, more preferably 97% or more by mass, and even more preferably 98% or more by mass).

[0172] The weight-average molecular weight of the acrylic resin is preferably, but not particularly limited to, 10,000 or more, more preferably 30,000 or more, further preferably 50,000 or more, even more preferably 60,000 or more, and still more preferably 70,000 or more. Furthermore, the weight-average molecular weight of the acrylic resin is preferably 250,000 or less, more preferably 200,000 or less, further preferably 150,000 or less, even more preferably 100,000 or less, and still even more preferably 90,000 or less.

[0173] The glass transition temperature of the acrylic resin layer 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 still more preferably 105°C or higher. There is no particular upper limit, but in practice it is, for example, 200°C or lower.

[0174] The glass transition temperature was measured according to the description in paragraph

[0056] of Japanese Patent Application Publication No. 2022-080270.

[0175] In addition to the above-mentioned components, the acrylic resin layer may also contain inorganic particles, antioxidants, release agents, ultraviolet absorbers, heat stabilizers, flame retardants, flame retardant additives, colorants, antistatic agents, fluorescent whitening agents, antifogging agents, flow improvers, plasticizers, dispersants, antibacterial agents, anti-blocking agents, impact resistance improvers, slip resistance improvers, color improvers, acid scavengers, etc. One or more of these components may be used. The preferred content of the above components, in total, is 0-5% by mass of the acrylic resin layer; more preferably 0-3% by mass; further preferably 0-1% by mass; even more preferably 0-0.5% by mass; still more preferably 0-0.3% by mass; and even more preferably 0-0.1% by mass.

[0176] As described above, the acrylic resin layer in this embodiment may contain a flame retardant. Examples of flame retardants that can be included in the acrylic resin layer include phosphorus-based flame retardants and sulfonate metal salts, with phosphorus-based flame retardants being preferred.

[0177] Examples of phosphorus-based flame retardants include aromatic phosphate compounds, phosphazene compounds, phosphazene compounds, phosphonate metal salts, ammonium polyphosphate, melamine polyphosphate, phosphate ester amides, and red phosphorus, with aromatic phosphate compounds, phosphazene compounds, and phosphazene compounds being preferred.

[0178] Examples of aromatic phosphate compounds include resorcinol diphenyl phosphate, hydroquinone diphenyl phosphate, bisphenol A diphenyl phosphate, and biphenyl diphenyl phosphate. Commercially available examples include PX-202, CR-741, PX-200, and PX-201 manufactured by Daihachi Chemical Industry Co., Ltd., and FP-500, FP-600, FP-700, and PFR manufactured by ADEKA Corporation.

[0179] Examples of aromatic phosphate compounds include cyclic phenoxyphosphazenes and their derivatives. Commercially available examples include Rabitle FP-110 manufactured by Fushimi Pharmaceutical Co., Ltd.

[0180] Phosphenanthrene compounds are phosphorus-based flame retardants with at least one phosphenanthrene skeleton in the molecule. Commercially available products include HCA, HCA-HQ, BCA, SANKO-220, and M-Ester manufactured by Sanko Corporation.

[0181] Phosphonate metal salts are phosphonates and / or diphosphonates and / or polymers thereof. Examples of such salts include salts of calcium, aluminum, and zinc. Commercially available phosphonate metal salts include Clariant's Exolit (trademark registered) OP1230 and OP1240.

[0182] Phosphate ester amides are aromatic amide flame retardants containing phosphorus and nitrogen atoms. Among commercially available phosphate ester amides, SP-703 manufactured by Shikoku Kasei Corporation is preferred.

[0183] Examples of ammonium polyphosphates include ammonium polyphosphate, melamine-modified ammonium polyphosphate, and carbamoyl ammonium polyphosphate. Examples of melamine polyphosphates include melamine phosphate, melamine pyrophosphate, and phosphates formed with melamine, melamine, and melamine. MPP-A manufactured by Sanwa Chemical Co., Ltd., PMP-100 manufactured by Nissan Chemical Co., Ltd., and PMP-200 manufactured by Nissan Chemical Co., Ltd. are preferred.

[0184] When the acrylic resin layer contains a flame retardant (phosphorus-based flame retardant, sulfonate metal salt, or other flame retardant), its content relative to 100 parts by weight of the acrylic resin layer is preferably 1 part by weight or more, more preferably 2 parts by weight or more, further preferably 5 parts by weight or more, and even more preferably 7 parts by weight or more. The upper limit of the content of the aforementioned flame retardant relative to 100 parts by weight of the acrylic resin layer is preferably 25 parts by weight or less, more preferably 20 parts by weight or less, and even more preferably 15 parts by weight or less.

[0185] The acrylic resin layer may contain only one flame retardant or two or more. When containing two or more flame retardants, the total amount is preferably within the range described above.

[0186] The thickness of the acrylic resin layer is preferably 50 μm or more, more preferably 100 μm or more, and even more preferably 150 μm or more. By setting it above the above lower limit, it is not only easier to achieve molding, but also often the hardness can be improved. In addition, the upper limit of the acrylic resin layer thickness is preferably 1000 μm or less, more preferably 750 μm or less, and even more preferably 500 μm or less.

[0187] <Manufacturing Methods of Multilayer Materials> The multilayer body of this embodiment can be manufactured according to known methods.

[0188] The multilayer body of this embodiment can be manufactured, for example, by using a main extruder for extruding a polycarbonate resin layer forming composition and an auxiliary extruder for extruding an acrylic resin layer forming composition, melting and extruding the resin according to the conditions of each resin used, guiding it to a die, stacking it inside the die and forming it into a sheet, or stacking it after forming it into a sheet, to form a substrate. Then, an infrared absorption layer forming composition is coated on one side of the polycarbonate resin layer of the substrate and cured.

[0189] The multilayer body of this embodiment can be used directly or can be processed, especially by heating, to form a molded product.

[0190] <Application> The multilayer body of this embodiment can be applied to optical components, appearance design products, anti-reflective molded bodies, etc.

[0191] The multilayer body of this embodiment can be applied to components of display devices, electrical and electronic equipment, OA (office automation) equipment, portable information terminals, mechanical parts, home appliances, vehicle parts, various containers, lighting equipment, etc. It is particularly suitable for housings of various displays, electrical and electronic equipment, OA equipment, portable information terminals, and home appliances; surface films of lighting equipment and vehicle parts (especially automotive interior parts); optical materials of smartphones and touchscreens; and optical discs. The multilayer body of this embodiment is especially preferred for use as a dust cover for head-up displays.

[0192] Example The following examples illustrate the present invention in more detail. The materials, dosages, ratios, processing contents, and processing steps shown in the following examples can be appropriately modified 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.

[0193] When the measuring instruments used in the embodiments are difficult to obtain due to reasons such as production stoppage, other devices with equivalent performance can be used for measurement.

[0194] 1. Raw materials Carbamate acrylate: UN-3320HC, solid content 100% by mass, weight average molecular weight 1500, functional group number 6, manufactured by Nejou Kogyo Co., Ltd.

[0195] Solvent Yellow 163: Yellow dye, manufacturer (Kiwa Chemical Industry Co., Ltd.).

[0196] Solvent Red 27: Red dye, manufacturer (Oriental Chemical Industry Co., Ltd.).

[0197] Pigment Red 254 series pigment: Red pigment, produced using a pre-formed MIBK dispersion. Solid content 20% by mass. Manufacturer (Nikko BICS Co., Ltd.).

[0198] FeOOH-based pigments: Yellow pigments, using pre-prepared PGM dispersions. Solid content 20% by mass.

[0199] YMF-02A: CWO (cesium tungsten oxide) dispersion, CWO content 18.5% by mass, manufactured by Sumitomo Metal Mining Co., Ltd.

[0200] Omnirad 819: Acylphosphine oxide photopolymerization initiator, solid component 100% by mass, manufactured by IGM RESINS BV.

[0201] BYK-UV3575: Silicone-based leveling agent, manufactured by BYK Corporation.

[0202] PC / PMMA membrane: A double-layer membrane consisting of a polycarbonate resin layer and an acrylic resin layer, DF02U, manufactured by Mitsubishi Gas Chemical Co., Ltd., with a thickness of 0.375 mm.

[0203] The composition of the flame-retardant substrate is shown below.

[0204] [Table 1] E-2000F: A polycarbonate resin obtained by interfacial polymerization using bisphenol A as the starting material (Mitsubishi Gas Chemical Co., Ltd. E-2000F, viscosity-average molecular weight: 27000, Tg: 150℃).

[0205] KSS-FR: Manufactured by Arichem, KSS-FR stands for potassium diphenyl sulfone-3-sulfonate.

[0206] 2112: Tris(2,4-di-tert-butylphenyl) phosphite (phosphorus antioxidant, ADEKA stab2112 manufactured by ADEKA).

[0207] S-100A: Glyceryl monostearate (RIKEMAL S-100A manufactured by Riken Vitamin Co., Ltd.).

[0208] 80HD: Made by Asahi Kasei Co., Ltd., polymethylmethacrylate.

[0209] <Manufacturing of Flame-Retardant Substrates> Polycarbonate resin layer (PC layer) forming resin composition (granules) and acrylic resin layer forming resin composition (granules) were manufactured according to the following method. The components were weighed according to the addition amounts described in Table 1 (each component in Table 1 is expressed as a percentage by mass). Then, after mixing with a tumbler for 15 minutes, the mixture was melt-blended using a vented twin-screw extruder ("TEX30α" manufactured by Nippon Steel Co., Ltd., with a screw diameter of 32 mm, and the mixture was cut into granules. It should be noted that the polycarbonate resin layer forming resin composition (granules) was melt-blended at a temperature that was adjusted according to the resin viscosity between 260 and 300°C, while the acrylic resin layer forming resin composition (granules) was melt-blended at 260°C.

[0210] A multi-layer extrusion unit was used, comprising a single-screw extruder with a shaft diameter of 32 mm, a single-screw extruder with a shaft diameter of 65 mm, a feeding unit connected to all extruders, and a 650 mm wide T-die connected to the feeding unit, to form flame-retardant substrates. The acrylic resin layer resin compositions (granules) for each flame-retardant substrate shown in Table 1 were introduced into the single-screw extruder with a shaft diameter of 32 mm, and extrusion was performed at a barrel temperature of 240°C and a discharge rate of 0.3–6.4 kg / h. Furthermore, the polycarbonate resin layer forming resin compositions (granules) for each flame-retardant substrate shown in Table 1 were continuously introduced into the single-screw extruder with a shaft diameter of 65 mm, and extrusion was performed at a discharge rate of 17.4–23.5 kg / h, with the barrel temperature varying between 250°C and 290°C depending on the resin viscosity. The feeding unit connected to all extruders was equipped with two types of double-layer distributors (distribution pins), and extrusion and stacking were performed. The material is extruded into sheets using a T-shaped die connected to the front end of the extruder. Simultaneously, it is mirror-transferred using three mirror-polishing rollers with temperatures of 120°C, 120°C, and 140°C from the upstream side, while being cooled to obtain various flame-retardant substrates.

[0211] 2. Examples 1-13, Comparative Examples 1-3 Fabrication of Multilayers (Coating of Infrared Absorption Layers) The components (A), (B), and (C) shown in Tables 2 and 3, along with the leveling agent, were mixed and stirred to obtain a composition for forming an infrared absorbing layer. In Tables 2 and 3, the proportions of each component represent the amount of solid component (parts by mass).

[0212] The infrared absorption layer forming composition obtained above was applied to the coated surface of the substrate shown in Table 2 using a doctor blade coater. The coated infrared absorption layer forming composition was dried in an oven at 80°C for 3 minutes and then cured under nitrogen atmosphere using a Heraeus UV irradiation system until the cumulative light intensity reached 500 mJ / cm². 2 (UV illuminance meter manufactured by ORC, measuring wavelength 360nm).

[0213] <Hard coating on the opposite side> A hard coating is applied to the side of the multilayer body fabricated as described above, opposite to the side with the infrared absorption layer.

[0214] In Table 2, a and b represent the resin compositions used for the hard coating, which are described below.

[0215] a: Fujikura Chemicals HO3313U-10 b: A resin composition for a hard coat, which is prepared by mixing 67.5% by mass of industrially produced UN-3320HC on the root, 29.0% by mass of silica particles surface-treated with 3-acryloxypropyltrimethoxysilane, 2.5% by mass of a photoinitiator, and 1% by mass of a leveling agent.

[0216] The above resin composition for a hard coat was applied to the outermost surface (the surface of the acrylic resin layer) on the side opposite to the side provided with the infrared absorption layer of the multilayer body using a bar coater. The applied resin composition for a hard coat was dried at a temperature of 80°C for 3 minutes using an oven, and cured in a nitrogen atmosphere using a UV irradiation device manufactured by Heraeus until the cumulative light amount reached 500 mJ / cm 2 (UV illuminometer manufactured by ORC, measurement wavelength 360 nm), to form a hard coat with a thickness of 4 μm.

[0217] <Total spectral transmittance (%)> The total spectral transmittance of the multilayer body was measured in accordance with JIS K 7375:2008 using "HM-150" manufactured by the Color Technology Research Institute of Murakami, Japan.

[0218] <Transmittance at a wavelength of 1000 nm (%)> The transmittance of the multilayer body at a wavelength of 1000 nm was measured.

[0219] The transmittance was measured using a spectrophotometer U-4000 manufactured by Hitachi High-Technologies Corporation.

[0220] <Ratio (T / T1)> The ratio T / T1 of the total spectral transmittance T of the multilayer body to the transmittance T1 at a wavelength of 1000 nm was calculated.

[0221] <Haze of the multilayer body> The haze of the multilayer body was evaluated in accordance with JIS K 7136:2000. The haze was measured using "HM-150" manufactured by the Color Technology Research Institute of Murakami, Japan.

[0222] <a* value and b* value> The a* value and b* value of the multilayer body were evaluated in a transmission mode under D65 light source and 2° field of view conditions using a spectrocolorimeter / colorimeter "SD7000" manufactured by Nippon Denshoku Industries Co., Ltd.

[0223] <Projection image evaluation> A white image was projected through the above-obtained multilayer body using a projector. The hue of the projected image was evaluated as follows.

[0224] A: No change in hue was found B: Slight coloring was found. C: Significant coloring was found.

[0225] <FMVSS Test> For the multi-layer body obtained above, using the FMVSS No. 302 flammability test device, starting from the right end of the test piece (350 mm × 100 mm × 0.375 mm), it was brought into contact with a 38-mm-high combustion flame for 15 seconds, and the combustion speed within the 254-mm combustion distance between the marked lines was measured. The measurement was carried out without a heat-resistant metal support wire (wire) in the test fixture, and the evaluation was carried out as described below.

[0226] A: The test piece is non-combustible or self-extinguishes before reaching the A marked line. B: Self-extinguishes within 51 mm from the A marked line (and within 60 seconds) in the combustion distance. C: Although it burns continuously until before reaching the B marked line, the combustion speed is below 102 mm / min. D: Burns continuously until before reaching the B marked line, and the combustion speed is faster than 102 mm / min.

[0227] [Table 2] [Table 3] In the above table, the pigment red 254-based pigment and the FeOOH-based pigment respectively represent the amount of solid components.

[0228] In the above table, CWO represents the amount of CWO in the CWO dispersion (YMF-02A).

[0229] In the above table, on the PMMA side, HC records whether a hard coat is provided on the surface of the acrylic resin layer, and a and b represent the composition of the resin composition for the hard coat.

[0230] In the above table, the ratio (T / T1) represents the ratio T / T1 of the total spectral transmittance T of the multi-layer body to the transmittance T1 at a wavelength of 1000 nm.

[0231] As shown by the above results, the multi-layer body of the present invention has a low haze, the projected image is not bluish, a high total spectral transmittance, and a low near-infrared transmittance (Examples 1 to 9).

[0232] In contrast, when the infrared absorption layer contains only tungsten oxide pigment as a colorant (Comparative Example 1), the resulting multilayer exhibits greater tonal variation relative to a white image. Furthermore, when the infrared absorption layer contains other pigments besides tungsten oxide pigment as colorants (Comparative Example 2), although the resulting multilayer suppresses tonal variation relative to a white image, it ultimately leads to increased haze. Additionally, when the infrared absorption layer contains only dye as a colorant (Comparative Example 3), not only does the resulting multilayer exhibit tonal variation relative to a white image, but the blue hue is also stronger.

[0233] Symbol Explanation 1: Multi-layered body 2: Acrylic resin layer 3: Polycarbonate resin layer 4: Infrared absorption layer.

Claims

1. A multilayer comprising a substrate layer and an infrared absorbing layer, characterized in that: The infrared absorption layer comprises an ultraviolet-curable resin, two or more colorants, and a photopolymerization initiator. The colorant comprises tungsten oxide and dye.

2. The multilayer body according to claim 1, characterized in that: In the L*a*b* color system of the multilayer body, the absolute values ​​of a* and b* are each independently below 2.

0.

3. The multilayer body according to claim 1 or 2, characterized in that: When the full-spectrum transmittance T of the multilayer is above 81%, the ratio T / T1 to the transmittance T1 at a wavelength of 1000 nm is above 1.5; when the full-spectrum transmittance T of the multilayer is below 81%, the ratio T / T1 is above 2.

4. The multilayer body according to any one of claims 1 to 3, characterized in that: The substrate layer comprises an acrylic resin layer and a polycarbonate resin layer. The infrared absorbing layer is located on the side of the polycarbonate resin layer opposite to the acrylic resin layer.

5. The multilayer body according to claim 4, characterized in that: The content of sulfonate metal salt in at least one of the acrylic resin layer and the polycarbonate resin layer is 0.01 to 0.80 by mass.

6. The multilayer body according to claim 4, characterized in that: The content of sulfonate metal salt in the polycarbonate resin layer is 0.01 to 0.80% by mass.

7. The multilayer body according to any one of claims 1 to 6, characterized in that: The haze value measured according to JIS K 7136 is below 2.0%.

8. The multilayer body according to any one of claims 1 to 7, characterized in that: The infrared absorption layer contains more than 20% by mass of the tungsten oxide.

9. The multilayer body according to any one of claims 1 to 8, characterized in that: The infrared absorption layer contains 0.5 to 6% by mass of red colorant and yellow colorant, respectively.

10. The multilayer body according to any one of claims 1 to 9, characterized in that: The infrared absorption layer contains 0.5 to 6% by mass of red dye and yellow dye, respectively.

11. The multilayer body according to any one of claims 1 to 10, characterized in that: The multilayer body also has a hard coating. The hard coating layer is stacked in the following order: infrared absorption layer, polycarbonate resin layer, acrylic resin layer, and hard coating layer.

12. The multilayer body according to claim 11, characterized in that: The hard coating contains inorganic particles.

13. The multilayer body according to any one of claims 1 to 12, characterized in that: The multilayer body also has an anti-reflective layer.

14. The multilayer body according to any one of claims 1 to 13, characterized in that: The multilayer body also has a polarizing layer.

15. A dust cover for a head-up display, characterized in that: The dust cover for the head-up display comprises a multilayer body as described in any one of claims 1 to 14.

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