Laminates and head-up displays

Abstract

To provide a laminate that can improve flame retardancy. [Solution] The laminate 1 comprises a transparent substrate layer 2 and a resin layer overlapping the transparent substrate layer 2. The transparent substrate layer 2 has a layer 2A made of polycarbonate and a layer 2B made of polymethyl methacrylate that overlaps the polycarbonate layer 2A on the resin layer 3 side. The average thickness of the polymethyl methacrylate layer 2B is 40 μm or less. The average thickness of the resin layer 3 is 8 μm or more. The resin layer 3 contains a cured product of a first composition containing a phosphorus-containing polyfunctional (meth)acrylate compound that contains phosphorus atoms and has 2 or more (meth)acryloyl groups per molecule. The content of the phosphorus-containing polyfunctional (meth)acrylate compound in the first composition is 15% by mass or more and 30% by mass or less.

Description

Technical Field

[0001] The present disclosure relates to a laminated body and a head-up display, and more particularly to a laminated body provided with a transparent base material layer and a head-up display.

Background Art

[0002] In recent years, in order for a driver to safely drive a vehicle or the like, a head-up display that displays an image such as driving support information on a display such as a display and reflects this image on a mirror to project it as a virtual image on a windshield or the like has been used.

[0003] In addition, recently, due to an increase in fire accidents caused by traffic accidents, the requirement for flame retardancy of in-vehicle parts has been increasing. As a flame retardancy standard for in-vehicle interior parts, there is the FMVSS (US Federal Motor Vehicle Safety Standard) No. 302 standard, and for a head-up display, it is required to meet the flame retardancy standard not only as a device but also as a cover member alone.

[0004] Patent Document 1 discloses a polarizing member used as a cover member of a head-up display. This polarizing member includes a polarizing plate, a first support plate and a second support plate including a flame-retardant plastic plate, an ultraviolet absorption layer, and a hard coat layer. Patent Document 2 discloses a resin glazing used as a cover member of a head-up display. This resin glazing has (A) at least one light reflection layer, (B) one quarter-wave plate, and (C) a transparent resin base material.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

[0006] However, the laminates used as conventional cover members still have room for improvement in terms of flame retardancy.

[0007] The object of this disclosure is to provide a laminate that can improve flame retardancy and a head-up display using the same. [Means for solving the problem]

[0008] A laminate according to one aspect of the present disclosure comprises a transparent substrate layer and a resin layer overlapping the transparent substrate layer. The transparent substrate layer has a layer made of polycarbonate and a layer made of polymethyl methacrylate overlapping the polycarbonate layer on the resin layer side. The average thickness of the polymethyl methacrylate layer is 40 μm or less. The average thickness of the resin layer is 8 μm or more. The resin layer contains a cured product of a first composition containing a phosphorus-containing polyfunctional (meth)acrylate compound that contains a phosphorus atom and has 2 or more (meth)acryloyl groups per molecule. The content of the phosphorus-containing polyfunctional (meth)acrylate compound in the first composition is 15% by mass or more and 30% by mass or less.

[0009] A laminate according to another aspect of the present disclosure comprises a transparent substrate layer, a resin layer overlapping the transparent substrate layer, and an anti-reflective layer overlapping the resin layer on the side opposite to the transparent substrate layer. The transparent substrate layer has a layer made of polycarbonate and a layer made of polymethyl methacrylate overlapping the polycarbonate layer on the side of the resin layer. The average thickness of the polymethyl methacrylate layer is 40 μm or less. The average thickness of the resin layer is 2 μm or more. The average thickness of the anti-reflective layer is 0.05 μm or more and 0.2 μm or less. The resin layer contains a cured product of a first composition containing a phosphorus-containing polyfunctional (meth)acrylate compound that contains a phosphorus atom and has 2 or more (meth)acryloyl groups per molecule. The content of the phosphorus-containing polyfunctional (meth)acrylate compound in the first composition is 15% by mass or more and 30% by mass or less.

[0010] A head-up display according to one aspect of the present disclosure is a head-up display comprising a laminate and a display unit, wherein the display unit, the transparent substrate layer, and the resin layer are arranged in this order.

[0011] Another aspect of the present disclosure is a head-up display comprising a laminate and a display, wherein the display, the transparent substrate layer, the resin layer, and the anti-reflective layer are arranged in this order. [Effects of the Invention]

[0012] According to this disclosure, it is possible to provide a laminate that can improve flame retardancy and a head-up display using the same. [Brief explanation of the drawing]

[0013] [Figure 1] Figure 1 is a schematic cross-sectional view showing a laminate of a first embodiment of the present disclosure. [Figure 2] Figure 2 is a schematic cross-sectional view showing a laminate of a second embodiment of the present disclosure. [Figure 3]Figure 3A is a conceptual diagram showing the head-up display of the present disclosure mounted on a mobile device. Figure 3B is a schematic cross-sectional view showing the configuration of the head-up display of the present disclosure. [Modes for carrying out the invention]

[0014] 1. Overview The following describes the general structure of laminate 1, with reference to the drawings. Note that the drawings are schematic, and the size and thickness ratios of each component shown in the drawings do not necessarily reflect the actual dimensional ratios.

[0015] The inventors, through diligent research into the flame retardancy of laminates, discovered that the aforementioned problems could be solved by adjusting the thickness of specific layers constituting the laminate and by forming a resin layer using polymerizable compounds of specific types and concentrations, and thus completed this disclosure.

[0016] As shown in Figure 1, the laminate 1 of the first embodiment of this disclosure comprises a transparent substrate layer 2 and a resin layer 3 overlapping the transparent substrate layer 2. The transparent substrate layer 2 has a layer made of polycarbonate (hereinafter also referred to as PC layer 2A) and a layer made of polymethyl methacrylate (hereinafter also referred to as PMMA layer 2B) overlapping the resin layer 3 side of the PC layer 2A. Thus, in the laminate 1 of the first embodiment, the PC layer 2A, the PMMA layer 2B, and the resin layer 3 are laminated in this order. The average thickness of the PMMA layer 2B is 40 μm or less. The average thickness of the resin layer 3 is 8 μm or more.

[0017] Furthermore, the resin layer 3 in the laminate 1 of the first embodiment contains a cured product of a first composition (hereinafter also referred to as composition (X)) which contains a phosphorus-containing polyfunctional (meth)acrylate compound (hereinafter also referred to as compound (HP)) having two or more (meth)acryloyl groups per molecule. The content of compound (HP) in composition (X) is 15% by mass or more and 30% by mass or less.

[0018] The laminate 1 of the first embodiment can improve flame retardancy. Although the reason for achieving the above effect when the laminate 1 has the above structure is not necessarily clear, it can be speculated as follows, for example. In the laminate 1, a PMMA layer 2B with low flame retardancy is laminated on the PC layer 2A for the purpose of improving surface hardness and light resistance. Further, a resin layer 3 containing a cured product of a composition (X) containing a phosphorus-containing polyfunctional (meth)acrylate compound (HP) having a specific structure at a specific content rate is laminated on the PMMA layer 2B. The cured product constituting the resin layer 3 contains a phosphorus atom and has a moderately high crosslink density, and it is considered that the flammability is reduced. By setting the average thickness of the resin layer 3 to a specific value or more and setting the average thickness of the PMMA layer 2B adjacent to the resin layer 3 to a specific value or less, it is considered that the flame retardancy is increased.

[0019] As shown in FIG. 2, the laminate 1 of the second embodiment of the present disclosure includes a transparent base material layer 2, a resin layer 3 overlapping the transparent base material layer 2, and an antireflection layer 4 overlapping on the side opposite to the transparent base material layer 2 of the resin layer 3. The transparent base material layer 2 has a PC layer 2A and a PMMA layer 2B overlapping on the resin layer 3 side of the PC layer 2A. Thus, in the laminate 1 of the second embodiment, the PC layer 2A, the PMMA layer 2B, the resin layer 3, and the antireflection layer 4 are laminated in this order. The average thickness of the PMMA layer 2B is set to 40 μm or less. Further, the average thickness of the resin layer 3 is set to 2 μm or more.

[0020] Further, the resin layer 3 in the laminate 1 of the second embodiment contains a cured product of a composition (X) containing a compound (HP). The content rate of the compound (HP) in the composition (X) is set to 15 mass% or more and 30 mass% or less.

[0021] The laminate 1 of the second embodiment can improve flame retardancy. The reason why the laminate 1 achieves the above effect by having the above configuration is not necessarily clear, but it can be inferred as follows, for example. In the laminate 1, a PMMA layer 2B with low flame retardancy is laminated on the PC layer 2A for the purpose of improving surface hardness and light resistance, and a resin layer 3 containing a cured product of a composition (X) containing a compound (HP) having a specific structure at a specific content is laminated on the PMMA layer 2B, and an anti-reflective layer 4 having an average thickness within a specific range is laminated on the resin layer 3. The cured product constituting this resin layer 3 contains phosphorus atoms and has a moderately high crosslinking density, which is thought to reduce flammability, and it is thought that the flame retardancy is improved by making the average thickness of this resin layer 3 above a specific value and the average thickness of the PMMA layer 2B adjacent to the resin layer 3 below a specific value.

[0022] 2.Details <Laminate> <First Embodiment> As shown in Figure 1, the laminate 1 of the first embodiment comprises a transparent substrate layer 2 and a resin layer 3. The transparent substrate layer 2 has a PC layer 2A and a PMMA layer 2B. In other words, the laminate 1 is formed by laminating the PC layer 2A, the PMMA layer 2B, and the resin layer 3 in this order. The laminate 1 may further comprise any layers other than the transparent substrate layer 2 and the resin layer 3. The laminate 1 of the first embodiment typically does not have an anti-reflective layer 4.

[0023] [Transparent base layer] The transparent substrate layer 2 has a PC layer 2A and a PMMA layer 2B.

[0024] The PC layer 2A is a layer made of polycarbonate. The PC layer 2A may contain other resins, additives, etc., other than polycarbonate, to the extent that it does not impair the effects of the present disclosure.

[0025] PMMA layer 2B is a layer made of polymethyl methacrylate. PMMA layer 2B may contain other resins other than polymethyl methacrylate, to the extent that it does not impair the effects of the present disclosure.

[0026] The average thickness of the PC layer 2A is, for example, 100 μm or more and 1000 μm or less, preferably 200 μm or more and 700 μm or less, and more preferably 300 μm or more and 500 μm or less.

[0027] It is important that the average thickness of PMMA layer 2B is 40 μm or less. If the average thickness of PMMA layer 2B exceeds 40 μm, the flame retardancy decreases. This average thickness is preferably 35 μm or less, more preferably 25 μm or less, and even more preferably 15 μm or less. This average thickness is, for example, 1 μm or more, and preferably 5 μm or more. In this case, the flame retardancy can be further improved.

[0028] The "average thickness" of a layer refers to the arithmetic mean of the thicknesses measured at multiple points (for example, any 10 points) in the cross-section of the PC layer 2A or PMMA layer 2B.

[0029] The total thickness of the transparent substrate layer 2 is, for example, 100 μm or more and 1000 μm or less, preferably 250 μm or more and 750 μm or less, and more preferably 300 μm or more and 500 μm or less.

[0030] The retardation value of the transparent substrate layer 2 is preferably 100 nm or less. In this case, the image quality, such as brightness and contrast of the head-up display projected image, can be improved, and the appearance quality can also be improved, such as making rainbow irregularities less visible. This retardation value is more preferably 70 nm or less, and even more preferably 40 nm or less. This retardation value is, for example, 10 nm or more. The "retardation value" is a value calculated as the product of the thickness of the transparent substrate layer 2 and the birefringence (ΔN).

[0031] [Resin layer] The resin layer 3 is a layer laminated on the PMMA layer 2B and is provided to enhance the flame retardancy of the laminate 1.

[0032] The resin layer 3 contains a cured product of composition (X). Preferably, the resin layer 3 consists of a cured product of composition (X). The resin layer 3 can be formed by polymerizing and curing a polymerizable compound having an ethylenically unsaturated group contained in composition (X). Examples of ethylenically unsaturated groups include vinyl groups, allyl groups, (meth)acryloyl groups, and styryl groups. Among these, (meth)acryloyl groups are preferred. In this specification, "(meth)acry" means either or both acry and methacry.

[0033] [Composition (X)] Composition (X) contains a polymerizable compound that includes a phosphorus atom and has two or more (meth)acryloyl groups per molecule (phosphorus-containing polyfunctional (meth)acrylate compound, compound (HP)). Composition (X) preferably contains other polymerizable compounds other than compound (HP), and preferably contains a hindered amine-based light stabilizer. Composition (X) may also contain other components such as a radical polymerization initiator.

[0034] (Compound (HP)) Compound (HP) is a compound containing a phosphorus atom and having two or more (meth)acryloyl groups per molecule. The inclusion of compound (HP) in composition (X) results in the formed resin layer 3 containing a phosphorus atom and having an appropriate crosslinking density. As a result, the flame retardancy of the laminate 1 is enhanced.

[0035] It is important that the number of (meth)acryloyl groups in compound (HP) is two or more. Preferably, this number is three or more. Also, for example, this number is six or less, and preferably four or less. In this case, the crosslinking density of the resin layer 3 becomes more appropriate, and as a result, the flame retardancy of the laminate 1 can be further improved.

[0036] Examples of compounds (HP) include tris(meth)acryloyl phosphate tris(meth)acryloyl esters such as tris(meth)acryloyloxyalkyl phosphates like trisacryloyloxyethyl phosphate and di(meth)acryloyl phosphate di(meth)acryloyl phosphates like bis(meth)acryloyloxyalkyl acid phosphate. A commercially available example of a compound (HP) is "Viscoat V3PA" manufactured by Osaka Organic Chemical Industry Co., Ltd.

[0037] It is important that the content of compound (HP) in composition (X) is 15% by mass or more and 30% by mass or less. If the content of compound (HP) is outside the above range, the flame retardancy will decrease. This content is preferably 17% by mass or more, and more preferably 18% by mass or more. This content is preferably 25% by mass or less, more preferably 22% by mass or less, and even more preferably 20% by mass or less.

[0038] (Compound (HA)) Composition (X) may also contain other polymerizable compounds besides compound (HP), such as a compound that does not contain a phosphorus atom and has a (meth)acryloyl group (hereinafter also referred to as compound (HA)).

[0039] Examples of compound (HA) include phosphorus-free polyfunctional (meth)acrylate compounds that do not contain phosphorus atoms, have an acrylic equivalent of 200 or less, and have 4 or more (meth)acryloyl groups per molecule (hereinafter also referred to as compound (HA-1)), and compounds (HA) other than compound (HA-1) (hereinafter also referred to as compound (HA-2)).

[0040] The number of (meth)acryloyl groups in compound (HA-1) is 4 or more, preferably 5 or more, and more preferably 6 or more. This number is, for example, 8 or less. The acrylic equivalent of compound (HA-1) is 200 or less, preferably 150 or less, and more preferably 120 or less. This acrylic equivalent is, for example, 80 or more, and preferably 100 or more. "Acrylic equivalent" refers to the value obtained by dividing the molecular weight of the compound by the number of (meth)acryloyl groups that the compound has. By setting the number of (meth)acryloyl groups and the acrylic equivalent of compound (HA-1) within the above range, the crosslinking density of the formed resin layer 3 can be increased, and the flame retardancy of the laminate 1 can be further improved.

[0041] Examples of compounds (HA-1) include pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, and dipentaerythritol hexa(meth)acrylate.

[0042] If composition (X) contains compound (HA-1), the content of compound (HA-1) in composition (X) is, for example, 10% by mass or more, preferably 20% by mass or more, and more preferably 23% by mass or more. This content is, for example, 80% by mass or less, preferably 70% by mass or less, more preferably 50% by mass or less, and even more preferably 30% by mass or less.

[0043] Compound (HA-2) is a compound that does not contain a phosphorus atom, has 3 or fewer (meth)acryloryl groups, or has an acrylic equivalent of more than 200. When composition (X) contains compound (HA-2), the crosslinking density of the cured product can be adjusted, thereby further improving the flame retardancy of laminate 1. Examples of compound (HA-2) include EO (ethylene oxide) modified bisphenol A di(meth)acrylate.

[0044] If composition (X) contains compound (HA-2), the content of compound (HA-2) in composition (X) is, for example, 20% by mass or more, preferably 30% by mass or more, and more preferably 40% by mass or more. This content is, for example, 90% by mass or less, preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 50% by mass or less.

[0045] (HALS) Composition (X) preferably contains hindered amine light stabilizers (HALS). HALS refers to a compound having a structure in which all hydrogen atoms bonded to the carbon atoms at positions 2 and 6 of piperidine are replaced with methyl groups. By containing HALS, composition (X) can suppress the occurrence of whitening of the cured product under humid heat conditions. The reason for this is not entirely clear, but for example, it is thought that the basicity of HALS neutralizes acidic groups such as phosphate groups that are generated by hydrolysis from the compound (HP) in the cured product under humid heat conditions and cause whitening.

[0046] Examples of HALS include compounds represented by the following formula (1).

[0047] [ka]

[0048] In formula (1), R 1 is a hydrogen atom or an alkyl group. * indicates the site that bonds to the -O- in -COO.

[0049] R in equation (1) 1 Preferably, the atom is a hydrogen atom. In this case, the basicity of HALS is increased, and the occurrence of whitening in the cured product can be further suppressed.

[0050] Examples of commercially available HALS products include ADEKA's ADEKA stubs LA-52, LA-57, LA-63P, LA-68, LA-72, LA-77, and LA-77G.

[0051] If composition (X) contains HALS, the HALS content in composition (X) is, for example, 1% by mass or more, preferably 3% by mass or more, more preferably 6% by mass or more, and even more preferably 8% by mass or more. This content is, for example, 20% by mass or less, preferably 15% by mass or less, more preferably 13% by mass or less, and even more preferably 10% by mass or less.

[0052] (Other ingredients) Composition (X) typically contains a radical polymerization initiator as another component. Composition (X) may also contain a dispersant, an ultraviolet absorber, and the like.

[0053] (Radical polymerization initiator) A radical polymerization initiator is a substance that causes curing by polymerizing the polymerizable compound in composition (X). Examples of radical polymerization initiators include photo-radical polymerization initiators that cleave upon exposure to light and generate radicals, and thermal radical polymerization initiators that cleave upon exposure to heat and generate radicals. When forming the resin layer 3 by photocuring, it is preferable to use a photo-radical polymerization initiator as the radical polymerization initiator.

[0054] Examples of photoradical polymerization initiators include benzophenone compounds, acetophenone compounds such as α-aminoalkylphenone and α-hydroxyalkylphenone, acylphosphine oxide compounds, titanocene compounds, oxime ester compounds, benzoin ether compounds, and thioxanthones.

[0055] Composition (X) may contain a photosensitizer in addition to, or in place of, the photoradical polymerization initiator. Examples of photosensitizers include n-butylamine, triethylamine, tri-n-butylphosphine, and thioxanthone.

[0056] If composition (X) contains a radical polymerization initiator, the content of the radical polymerization initiator in composition (X) is preferably, for example, 0.1% by mass or more, and preferably 0.5% by mass or more. This content is preferably, for example, 3% by mass or less, and preferably 1.5% by mass or less.

[0057] If composition (X) contains components other than the radical polymerization initiator, the content of the other components in composition (X) is, for example, 0.1% by mass or more and 3% by mass or less.

[0058] The resin layer 3 can be formed by coating composition (X) onto, for example, the surface of the PMMA layer 2B of the transparent substrate layer 2, and then photocuring the composition (X) by irradiating it with ultraviolet light. It is important that the average thickness of the resin layer 3 is 8 μm or more. If the average thickness of the resin layer 3 is less than 8 μm, the flame retardancy will decrease. The average thickness of the resin layer 3 is preferably 10 μm or more, and more preferably 12 μm or more. In this case, the flame retardancy of the laminate 1 can be further improved. The average thickness of the resin layer 3 is, for example, 20 μm or less, and preferably 15 μm or less. The "average thickness" of the resin layer means the arithmetic mean of the thickness measured at multiple points (for example, 10 points) in the cross-section of the resin layer 3. The refractive index of the resin layer 3 is, for example, greater than 1.50, preferably 1.52 or more, and for example 1.60 or less.

[0059] <Second Embodiment> As shown in Figure 2, the laminate 1 of the second embodiment comprises a transparent substrate layer 2 having a PC layer 2A and a PMMA layer 2B, a resin layer 3, and an anti-reflective layer 4 overlapping the resin layer 3 on the opposite side from the transparent substrate layer 2. Thus, the laminate 1 of the second embodiment is formed by laminating the PC layer 2A, the PMMA layer 2B, the resin layer 3, and the anti-reflective layer 4 in this order. The laminate 1 of the second embodiment differs from the laminate 1 of the first embodiment in that it further comprises an anti-reflective layer 4 on the opposite side of the resin layer 3 from the transparent substrate layer 2, and in that the average thickness range of the resin layer 3 is different. In the following description, components that overlap with the first embodiment may be denoted by the same reference numerals in the drawings, and their specific descriptions may be omitted.

[0060] [Transparent base layer] The transparent substrate layer 2 in the laminate 1 of the second embodiment is the same as the transparent substrate layer 2 in the laminate 1 of the first embodiment described above.

[0061] [Resin layer] The resin layer 3 in the laminate 1 of the second embodiment is the same as the resin layer 3 in the laminate 1 of the first embodiment in terms of the composition of the composition (X) that forms the resin layer 3, except for the range of average thickness.

[0062] It is important that the average thickness of the resin layer 3 is 2 μm or more. If the average thickness of the resin layer 3 is less than 2 μm, the flame retardancy will decrease. Preferably, the average thickness of the resin layer 3 is 3 μm or more. In this case, the flame retardancy of the laminate 1 can be further improved. The average thickness of the resin layer 3 is, for example, 20 μm or less, preferably 15 μm or less, more preferably 10 μm or less, and even more preferably 5 μm or less.

[0063] [Anti-reflection layer] The anti-reflective layer 4 is a layer that prevents light that strikes its surface from being reflected. The refractive index of the anti-reflective layer 4 is usually smaller than that of the resin layer 3. By incorporating the anti-reflective layer 4, the laminate 1 is effective in reducing double images (ghosting) that affect the image quality of the head-up display projection image, and in reducing stray light from sunlight or the head-up display projection image.

[0064] The anti-reflective layer 4 preferably contains at least one of a cured product of a second composition (hereinafter also referred to as composition (Y)) containing a fluorine-containing (meth)acrylate compound having a fluorine atom, and a cured product of a third composition (hereinafter also referred to as composition (Z)) containing hollow silica and a (meth)acrylate compound. By using a fluorine-containing composition (Y) or a composition (Z) containing hollow silica and a (meth)acrylate compound in the anti-reflective layer 4, flame retardancy can be further improved. The anti-reflective layer 4 can be formed by polymerizing and curing the polymerizable compounds in composition (Y) and / or composition (Z).

[0065] (Composition (Y)) Composition (Y) contains a fluorine-containing (meth)acrylate compound having a fluorine atom (hereinafter also referred to as compound (AF)). In addition to compound (AF), composition (Y) may also contain a (meth)acrylate compound that does not contain a fluorine atom (hereinafter also referred to as compound (AO)), and may also contain components such as radical polymerization initiators.

[0066] Examples of compounds (AF) include 2,2,2-trifluoroethyl (meth)acrylate, 2,2,3,3,4,4,4-heptafluorobutyl (meth)acrylate, 2,2,3,3,4,4,5,5,6,6,6-undecafluorohexyl (meth)acrylate, 2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-pentadecafluorooctyl (meth)acrylate, 2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-nonadecafluorodecyl (meth)acrylate, perfluoroethyl (meth)acrylate, perfluorobutyl (meth)acrylate, perfluorohexyl (meth)acrylate, perfluorooctyl (meth)acrylate, and perfluorodecyl (meth)acrylate.

[0067] Examples of compound (AO) include compounds similar to compound (HA) in composition (X) described above. Examples of radical polymerization initiators include those similar to the photoradical polymerization initiator in composition (X) described above.

[0068] (Composition (Z)) Composition (Z) contains hollow silica (hereinafter also referred to as hollow silica (S)) and a (meth)acrylate compound (hereinafter also referred to as compound (AM)). In addition to the above, composition (Z) may also contain components such as radical polymerization initiators.

[0069] "Hollow silica" refers to silica (silicon dioxide, SiO2) having an outer shell and a hollow portion within the outer shell. Hollow silica (S) contains air in the hollow portion. Since the refractive index of air is 1.0, the refractive index of hollow silica (S) can be a low value, such as 1.20 to 1.29. Therefore, the cured product of composition (Z) will have a low refractive index. The shape of hollow silica (S) is, for example, approximately spherical or spherical.

[0070] Examples of commercially available hollow silica (S) include Thru-Ria 4320 and 4110 (both manufactured by JGC Catalysts & Chemicals Co., Ltd.).

[0071] Examples of compound (AM) include compounds similar to compound (HA) in composition (X) described above. Examples of radical polymerization initiators include photoradical polymerization initiators in composition (X) described above.

[0072] The anti-reflective layer 4 can be formed by coating, for example, the surface of the resin layer 3 with at least one of composition (Y) and composition (Z), and then photocuring the composition (Y) or (Z) by irradiating it with ultraviolet light or the like. By using composition (Y) or composition (Z) to form the anti-reflective layer 4, the flame retardancy of the laminate 1 can be further improved.

[0073] It is important that the average thickness of the anti-reflective layer 4 is between 0.05 μm and 0.2 μm. By keeping the average thickness of the anti-reflective layer 4 within this range, reflection can be properly prevented. If the average thickness exceeds 0.2 μm, reflection cannot be properly prevented. The "average thickness" of the anti-reflective layer refers to the arithmetic mean of the thickness measured at multiple points (for example, 10 points) in the cross-section of the anti-reflective layer 4. The refractive index of the anti-reflective layer 4 is, for example, 1.50 or less, and preferably 1.45 or less. The refractive index of the anti-reflective layer 4 is, for example, 1.25 or more.

[0074] The laminate 1 can be suitably used for protecting various devices and films, and is particularly suitable for use as a head-up display cover.

[0075] <Head-Up Display> Figures 3A and 3B illustrate the case in which the laminate 1 of this embodiment is used as a cover 14 for a head-up display 10 (hereinafter also referred to as HUD 10). The HUD 10 consists of, for example, a display unit 11, an infrared absorber 12 and a mirror 13 in a case 16, and a cover 14 placed at the opening of the case 16. The cover 14 may consist only of the laminate 1, or it may be a combination of the laminate 1 and an optical member 15 that transmits visible light to the inside of the laminate 1 in the HUD 10. Examples of materials that make up the optical member 15 include glass and cycloolefin polymer.

[0076] The HUD 10 is mounted on a mobile vehicle 300 to enable the driver 200 to safely operate the vehicle, and displays driving assistance information from the display unit 11 as images 21 on the windshield 20. Infrared light 62, ultraviolet light 63, and visible light 64 contained in the natural light 61 from the sun 6 that passes through the windshield 20 and cover 14 are reflected by the mirror 13 and go through the infrared absorber 12 towards the display unit 11. The display unit 11 is, for example, a liquid crystal display. With this configuration, the driver 200 of the mobile vehicle 300 sees the images 21 on the windshield 20 as a virtual image 23 projected into the space in front of the mobile vehicle 300 (outside the vehicle) via the HUD 10. In other words, the driver 200 operating the mobile vehicle 300 can see the virtual image 23 superimposed on the real space that extends in front of the mobile vehicle 300.

[0077] The laminate 1 is arranged such that the PMMA layer 2B in the transparent substrate layer 2 faces inward towards the HUD 10, and the resin layer 3 or anti-reflective layer 4 faces outward towards the HUD 10. That is, if the laminate 1 is the laminate of the first embodiment, the HUD 10 has the display unit 11, the transparent substrate layer 2, and the resin layer 3 arranged in this order. If the laminate 1 is the laminate of the second embodiment, the HUD 10 has the display unit 11, the transparent substrate layer 2, the resin layer 3, and the anti-reflective layer 4 arranged in this order.

[0078] Since the HUD10 uses the laminate 1 described above, its flame retardancy is improved. [Examples]

[0079] The present disclosure will be described in more detail below with reference to examples, but the present disclosure is not limited to the examples.

[0080] <Fabrication of laminates> Examples 1-1 and 1-2 (and Comparative Examples 1-1 and 1-2) were prepared as laminates of the first embodiment (without anti-reflective layer), and Examples 2-1 to 2-5 (and Comparative Examples 2-1 to 2-4) were prepared as laminates of the second embodiment (with anti-reflective layer). The materials used in the production of the laminates in the examples and comparative examples, and the components used in the preparation of compositions (X) to (Z) are shown below.

[0081] (Transparent base layer) • PC / PMMA film (a film with an integrated PC layer and PMMA layer): "DF02PU" manufactured by Mitsubishi Gas Chemical Co., Ltd.

[0082] (Resin layer) (Composition (X)) • Compound (HP) #1: "Viscoat V3PA" manufactured by Osaka Organic Chemical Industry Co., Ltd.: Trisacryloyloxyethyl phosphate Compound (HO) #1: "Light Acrylate P-1A(N)" manufactured by Kyoeisha Chemical Co., Ltd.: 2-Acryloyloxyethyl acid phosphate • Radical polymerization initiator #1: Omnirad127 from IGM Resins. HALS #1: "ADEKA LA-57" manufactured by ADEKA Corporation Compound (HA-1) #1: Dipentaerythritol pentaacrylate (A-9570W manufactured by Shin-Nakamura Chemical Industry Co., Ltd.) • Compound (HA-2) #1: "Z-607-5HL" manufactured by Aica Kogyo Co., Ltd. • Compound (HA-2) #2: EO-modified bisphenol A diacrylate ("Light Acrylate BP-4EAL" manufactured by Kyoeisha Chemical Co., Ltd.)

[0083] (Anti-reflection layer) (Composition (Y)) • Compound (AF) #1: "AR110" manufactured by Daikin Industries, Ltd. Compound (AO) #1: Dipentaerythritol pentaacrylate (A-9570W, manufactured by Shin-Nakamura Chemical Industry Co., Ltd.) • Radical polymerization initiator #2: "Omnirad184" manufactured by IGM Resins. • Radical polymerization initiator #3: Omnirad907 from IGM Resins. (Composition (Z)) • Compound (AM) #1: "Z-607-5HL" manufactured by Aica Kogyo Co., Ltd. • Hollow silica (S) #1: "Thru-Ria 4320" manufactured by JGC Catalysts & Chemicals Co., Ltd. (average particle size 60 nm, refractive index 1.25) • Radical polymerization initiator #1: Omnirad127 from IGM Resins.

[0084] Each of compositions (X) to (Z) was prepared by mixing the components of the type and amount (parts by mass) shown in Table 1.

[0085] (Preparation of resin layer) As shown in Table 1, each composition (X) was applied to the surface of each transparent substrate layer so that the thickness of the cured resin layer was the average thickness shown in Table 1, and then each resin layer was prepared by irradiating the composition (X) with ultraviolet light. In Comparative Example 1-2, it was not possible to form a resin layer.

[0086] (Fabrication of anti-reflective layer) As shown in Table 1, for those with an anti-reflective layer, each anti-reflective layer was fabricated by applying either composition (Y) or composition (Z) to the surface of the prepared resin layer after curing, such that the average thickness of the cured anti-reflective layer was 0.1 μm, and then irradiating composition (Y) or composition (Z) with ultraviolet light.

[0087] As described above, laminates of each example and comparative example were obtained.

[0088] <Rating> Each of the laminates prepared as described above was evaluated for flame retardancy and in-vehicle environmental conditions using the methods described below. The evaluation results are shown in Table 1 below. In Table 1, "(*1)" in Comparative Example 1-2 indicates that a resin layer could not be formed.

[0089] [Flame retardant] For each of the laminates prepared as described above, the combustion rate (mm / min) was measured using a method compliant with FMVSS No. 302, without wires and with the PMMA layer surface as the combustion surface. The values ​​for each combustion rate and the evaluation of flame retardancy are shown in Table 1. Flame retardancy can be evaluated according to the following criteria. A (Good): The combustion rate was 102 mm / min or less. B (Slightly Poor): Combustion rate was between 102 mm / min and 135 mm / min. C (Poor): The combustion rate exceeded 135 mm / min.

[0090] [In-vehicle environmental testing] The laminated structures prepared as described above were subjected to various in-vehicle environmental tests under the following conditions. (Heat and moisture resistance) • Initial stage (before testing): Laminate before performing the moisture and heat resistance test. • Humidity and heat resistance test 1: A humidity and heat resistance test was conducted under the conditions of 85°C, 85% RH, and 500 hours. • Humidity and heat resistance test 2: A humidity and heat resistance test was conducted under the conditions of 90°C, 95% RH, and 72 hours.

[0091] (heat resistance) • Heat resistance test: A heat resistance test was conducted under the conditions of 120°C for 500 hours.

[0092] (Lightfastness) • Lightfastness test (QUV): Irradiance of 1.55 W / m² at a wavelength of 340 nm. 2 Then, a lightfastness test was conducted under the conditions of 80°C for 96 hours without watering.

[0093] Each of these tests was evaluated according to the following criteria. A: The appearance after the test was good. B: Whitening and other issues were observed in the appearance after the test.

[0094] [Table 1]

[0095] As can be seen from the results in Table 1, the laminates of the examples exhibit excellent flame retardancy.

[0096] (summary) As is clear from the above embodiments and examples, this disclosure includes the following aspects. In the following, reference numerals are enclosed in parentheses solely to indicate their correspondence with the embodiments.

[0097] The laminate (1) of the first embodiment comprises a transparent substrate layer (2) and a resin layer (3) overlapping the transparent substrate layer (2). The transparent substrate layer (2) has a layer (2A) made of polycarbonate and a layer (2B) made of polymethyl methacrylate that overlaps the polycarbonate layer (2A) on the side with the resin layer (3). The average thickness of the polymethyl methacrylate layer (2B) is 40 μm or less. The average thickness of the resin layer (3) is 8 μm. The resin layer (3) contains a cured product of composition (X) containing a phosphorus-containing polyfunctional (meth)acrylate compound that contains a phosphorus atom and has 2 or more (meth)acryloyl groups per molecule. The content of the phosphorus-containing polyfunctional (meth)acrylate compound in composition (X) is 15% by mass or more and 30% by mass or less.

[0098] According to the first embodiment, the laminate (1) can have improved flame retardancy.

[0099] In the laminate (1) of the second embodiment, in the first embodiment, composition (X) further contains a phosphorus-free polyfunctional (meth)acrylate compound that does not contain phosphorus atoms, has an acrylic equivalent of 200 or less, and has 4 or more (meth)acryloyl groups per molecule.

[0100] According to the second embodiment, the laminate (1) can have its flame retardancy further improved.

[0101] In the laminate (1) of the third embodiment, the composition (X) further contains a hindered amine-based light stabilizer, in the first or second embodiment.

[0102] According to the third embodiment, the laminate (1) can suppress the occurrence of whitening.

[0103] In the laminate (1) of the fourth embodiment, in the third embodiment, the content of the phosphorus-free polyfunctional (meth)acrylate compound in composition (X) is 20% by mass or more and 70% by mass or less, and the content of the hindered amine-based light stabilizer is 3% by mass or more and 15% by mass or less.

[0104] According to the fourth embodiment, the laminate (1) can further improve flame retardancy and further improve the occurrence of whitening.

[0105] In the laminate (1) of the fifth embodiment, the retardation value of the transparent substrate layer (2) is 100 nm or less in any one of the first to fourth embodiments.

[0106] According to the fifth aspect, the laminate (1) can improve image quality such as brightness and contrast after projection on the head-up display, and can also improve appearance quality such as making rainbow irregularities less visible.

[0107] The laminate (1) of the sixth embodiment comprises a transparent substrate layer (2), a resin layer (3) overlapping the transparent substrate layer (2), and an anti-reflective layer (4) overlapping the resin layer (3) on the side opposite to the transparent substrate layer (2). The transparent substrate layer (2) has a layer (2A) made of polycarbonate and a layer (2B) made of polymethyl methacrylate overlapping the polycarbonate layer (2A) on the side of the resin layer (3). The average thickness of the polymethyl methacrylate layer (2B) is 40 μm or less. The average thickness of the resin layer (3) is 2 μm or more. The average thickness of the anti-reflective layer (4) is 0.05 μm or more and 0.2 μm or less. The resin layer (3) contains a cured product of composition (X) containing a phosphorus-containing polyfunctional (meth)acrylate compound that contains a phosphorus atom and has 2 or more (meth)acryloyl groups per molecule. The content of the phosphorus-containing polyfunctional (meth)acrylate compound in composition (X) is 15% by mass or more and 30% by mass or less.

[0108] According to the sixth aspect, the laminate (1) can improve flame retardancy and also improve the efficiency of light transmission.

[0109] In the laminate (1) of the seventh embodiment, the refractive index of the anti-reflective layer (4) is 1.45 or less, as in the sixth embodiment.

[0110] According to the seventh aspect, the laminate (1) can further suppress the reflection of light on the surface of the anti-reflective layer (4).

[0111] In the laminate (1) of the eighth embodiment, the anti-reflective layer (4) comprises a cured product of a composition (Y) containing a fluorine-containing (meth)acrylate compound having a fluorine atom, in the sixth or seventh embodiment.

[0112] According to the eighth aspect, the laminate (1) can have its flame retardancy further improved.

[0113] In the laminate (1) of the ninth embodiment, in any one of the sixth to eighth embodiments, the anti-reflective layer (4) comprises hollow silica and a cured product of composition (Z) containing a (meth)acrylate compound.

[0114] According to the ninth aspect, the laminate (1) can have its flame retardancy further improved.

[0115] In the tenth embodiment (1), the laminate is for a head-up display cover in any one of the first to fifth embodiments.

[0116] According to the tenth embodiment, the laminate (1) can be suitably used as a cover (14) for a head-up display (10).

[0117] In the laminate of the eleventh embodiment (1), it is for a head-up display cover in any one of the sixth to ninth embodiments.

[0118] According to the eleventh embodiment, the laminate (1) can be suitably used as a cover (14) for a head-up display (10).

[0119] The head-up display (10) of the twelfth embodiment comprises a laminate (1) of the tenth embodiment and a display unit (11), wherein the display unit (11), a transparent substrate layer (2), and a resin layer (3) are arranged in this order.

[0120] According to the twelfth embodiment, a head-up display (10) with improved flame retardancy can be provided.

[0121] The head-up display (10) of the 13th embodiment comprises a laminate (1) of the 11th embodiment and a display unit (11), wherein the display unit (11), a transparent substrate layer (2), a resin layer (3), and an anti-reflective layer (4) are arranged in this order.

[0122] According to the 13th embodiment, a head-up display (10) with improved flame retardancy can be provided. [Explanation of Symbols]

[0123] 1. Laminate 2 Transparent base layer 2A Polycarbonate layer (PC layer) 2B Layer consisting of polymethyl methacrylate (PMMA layer) 3. Resin layer 4 Anti-reflection layer 10 Head-Up Display 11 Display 14 Cover

Claims

1. It comprises a transparent substrate layer and a resin layer overlapping the transparent substrate layer, The transparent substrate layer comprises a layer made of polycarbonate and a layer made of polymethyl methacrylate that overlaps the polycarbonate layer on the resin layer side. The average thickness of the layer made of the polymethyl methacrylate is 40 μm or less. The average thickness of the aforementioned resin layer is 8 μm or more. The aforementioned resin layer Cured product of a first composition containing a phosphorus-containing polyfunctional (meth)acrylate compound having a phosphorus atom and two or more (meth)acryloyl groups per molecule. Includes, The content of the phosphorus-containing polyfunctional (meth)acrylate compound in the first composition is 15% by mass or more and 30% by mass or less. Laminated structure.

2. The first composition is A phosphorus-free polyfunctional (meth)acrylate compound that does not contain phosphorus atoms, has an acrylic equivalent of 200 or less, and has 4 or more (meth)acryloyl groups per molecule. It further contains, The laminate according to claim 1.

3. The first composition is Hindered amine light stabilizers It further contains, The laminate according to claim 2.

4. In the first composition, The content of the phosphorus-free polyfunctional (meth)acrylate compound is 20% by mass or more and 70% by mass or less. The content of the aforementioned hindered amine-based light stabilizer is 3% by mass or more and 15% by mass or less. The laminate according to claim 3.

5. The retardation value of the transparent substrate layer is 100 nm or less. The laminate according to claim 1.

6. The device comprises a transparent substrate layer, a resin layer overlapping the transparent substrate layer, and an anti-reflective layer overlapping the resin layer on the side opposite to the transparent substrate layer. The transparent substrate layer comprises a layer made of polycarbonate and a layer made of polymethyl methacrylate that overlaps the polycarbonate layer on the resin layer side. The average thickness of the layer made of the polymethyl methacrylate is 40 μm or less. The average thickness of the aforementioned resin layer is 2 μm or more. The average thickness of the anti-reflective layer is 0.05 μm or more and 0.2 μm or less. The aforementioned resin layer Cured product of a first composition containing a phosphorus-containing polyfunctional (meth)acrylate compound having a phosphorus atom and two or more (meth)acryloyl groups per molecule. Includes, The content of the phosphorus-containing polyfunctional (meth)acrylate compound in the first composition is 15% by mass or more and 30% by mass or less. Laminated structure.

7. The refractive index of the anti-reflective layer is 1.45 or less. The laminate according to claim 6.

8. The anti-reflective layer, Cured product of a second composition containing a fluorine-containing (meth)acrylate compound having a fluorine atom. including, The laminate according to claim 6.

9. The anti-reflective layer, Cured product of the third composition containing hollow silica and (meth)acrylate compound including, The laminate according to claim 6.

10. This is for a head-up display cover. The laminate according to claim 1.

11. This is for a head-up display cover. The laminate according to claim 6.

12. A head-up display comprising a laminate according to claim 10 and a display unit, The display unit, the transparent substrate layer, and the resin layer are arranged in this order. Head-up display.

13. A head-up display comprising a laminate according to claim 11 and a display unit, The display unit, the transparent substrate layer, the resin layer, and the anti-reflective layer are arranged in this order. Head-up display.

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