Optical laminate

Abstract

The present application provides a means for thinning and simultaneously improving impact resistance and bending properties in an optical laminate including a thin film glass. The present application is an optical laminate sequentially provided with a constraint portion, a shock absorbing portion 1, a shock absorbing portion 2, and a thin film glass having a thickness in the range of 10 to 40 μm, wherein tan δ of the constraint portion is tan δ1, tan δ of the shock absorbing portion 1 is tan δ2, and tan δ of the shock absorbing portion 2 is tan δ3, and the tan δ1, the tan δ2, and the tan δ3 satisfy the following formula (1). tan δ1 < tan δ2 < tan δ3 (1).

Description

Technical Field

[0001] This invention relates to optical laminates. Background Technology

[0002] Recently, there has been a surge in the development of foldable and rollable flexible displays. Flexible displays consist of a cover glass unit for protecting the flexible display unit and a display unit containing a polarizer.

[0003] Here, the glass substrate used in the cover glass unit requires flexibility, so it needs to be changed to a resin substrate and a thin film of the glass substrate itself. However, from the perspective of a high-end feel and the folding habit when bending (durability), thin film glass has become the mainstream.

[0004] Thin-film glass is very fragile, and we are also developing displays for pen input, requiring a cover glass unit that can withstand the impact of pen input, demanding higher impact resistance than before. Furthermore, due to the characteristics of the device, it is necessary to further thin the cover glass unit.

[0005] Previously, to protect thin-film glass, protective films were developed using adhesives as bonding layers, or laminates with hard coatings stacked on top of protective films were constructed (see Korean Patent Publication No. 10-2020-0072643, corresponding to U.S. Patent Application Publication No. 2020 / 0194724). However, these laminates suffer from insufficient impact resistance. While methods exist to improve impact resistance by increasing the thickness of the laminate, this results in reduced flexibility, making it difficult to balance impact resistance. Furthermore, the thin-film production of the laminate becomes challenging.

[0006] As a technology for improving the impact resistance of the cover glass unit, Japanese Patent Application Publication No. 2020-139108 discloses an adhesive layer for organic EL display devices formed from an adhesive composition containing a (meth)acrylic polymer and an ultraviolet absorber with specific components. Summary of the Invention

[0007] However, the technology disclosed in Japanese Patent Application Publication No. 2020-139108 does not meet the requirements of thinning the cover glass unit while simultaneously improving impact resistance and flexibility.

[0008] The present invention was made based on the above circumstances, and its object is to provide a means for thinning in an optical laminate containing thin-film glass and simultaneously improving impact resistance and flexural strength.

[0009] Through repeated and in-depth research, the inventors discovered that the above-mentioned problems could be solved by the following optical laminate, thus completing the present invention.

[0010] That is, the present invention is an optical laminate comprising, in sequence, a constraint part, a damping part 1, a damping part 2, and a thin film glass with a thickness in the range of 10 to 40 μm. When the tanδ of the constraint part is set as tanδ1, the tanδ of the damping part 1 is set as tanδ2, and the tanδ of the damping part 2 is set as tanδ3, the tanδ1, tanδ2, and tanδ3 satisfy the relationship of the following formula (1).

[0011] tanδ1<tanδ2<tanδ3 (1) Attached Figure Description

[0012] Figure 1 This is a schematic diagram illustrating an example of a method for manufacturing thin-film glass. Symbol 21 represents the carrier substrate, symbol 22 represents the thin-film glass, symbol 23 represents the contact film, and symbol 24 represents electromagnetic radiation lines. Detailed Implementation

[0013] The present invention is an optical laminate comprising, in sequence, a constraint portion, a damping portion 1, a damping portion 2, and a thin film glass with a thickness in the range of 10 to 40 μm. When the tanδ of the constraint portion is set as tanδ1, the tanδ of the damping portion 1 is set as tanδ2, and the tanδ of the damping portion 2 is set as tanδ3, the tanδ1, tanδ2, and tanδ3 satisfy the following relationship (1).

[0014] tanδ1<tanδ2<tanδ3 (1)

[0015] The optical laminate of the present invention, having this configuration, can be thinned, thereby simultaneously improving impact resistance and flexural strength.

[0016] The exact reasons why the optical laminate of the present invention can achieve the effects described above are unclear, but it is believed to be due to the following mechanism. It should be noted that the following mechanism is based on speculation, and the present invention is not limited by the mechanism described herein.

[0017] Generally, optical laminates such as the cover glass unit consist of a constraint layer such as a PET film, a shock-absorbing adhesive layer, and a thin-film glass. However, optical laminates with this structure are insufficiently shock-resistant to pen input. The reasons are as follows: When the pen is input (dropped), energy (impact) is applied from the constraint portion towards the glass and laterally. This energy reaches the adhesive portion, which then begins to deflect. This deflection causes displacement at the interfaces of each portion. If the deflection is of a certain magnitude, it can absorb the interfacial displacement. However, if the deflection becomes too large, it becomes unable to absorb the interfacial displacement (stress), which is then transmitted towards the glass, causing the thin-film glass to crack.

[0018] Based on this insight, the inventors conducted repeated and in-depth research and found that an optical laminate with two damping parts placed between the outermost constraint part of the optical laminate and a thin film glass of a specific thickness, and with a specific relationship between the tanδ (loss tangent) of the constraint part and the tanδ of the two damping parts, exhibits high impact resistance to pen input.

[0019] The optical laminate of the present invention is constructed by stacking a constraint portion, a damping portion 1, a damping portion 2, and a thin-film glass in that order, with the value of tanδ increasing sequentially from the constraint portion to the damping portion 1 and the damping portion 2. This configuration allows for deformation of the constraint portion (the outermost layer) during pen input, with only the central portion of the two damping portions deforming accordingly. This releases the resulting offset stress in a direction perpendicular to the deflection direction, thus dispersing the offset stress at the ends without overall deflection. Therefore, it is believed that impact transmission to the thin-film glass can be prevented, suppressing breakage and improving impact resistance. The optical laminate of the present invention, with this configuration, is believed to achieve both impact resistance and flexibility without increasing its thickness.

[0020] If the relationship in equation (1) above is not satisfied, at least one of the impact resistance and bending resistance of the optical laminate becomes insufficient.

[0021] Hereinafter, embodiments of the optical laminate of the present invention will be described in detail. It should be noted that in this specification, the range “X~Y” means “X and above and Y and below”. Furthermore, unless otherwise specified, in this specification, operations and measurements of physical properties are performed under conditions of room temperature (20~25°C) and relative humidity 40~50%RH.

[0022] The optical laminate of the present invention sequentially comprises a constraint portion, a damping portion 1, a damping portion 2, and a thin film glass. Here, "sequentially comprised" means that the constraint portion, damping portion 1, damping portion 2, and thin film glass can be arranged sequentially, or other portions can be arranged between each portion and the thin film glass. In addition, even if a particular portion does not have a clear boundary, for example, if the tanδ of the upper and lower portions of a particular portion is different, and the relationship of the above formula (1) holds, it is also included in the present invention. For example, if the tanδ measured within 30% of the thickness from the upper portion of a particular portion differs from the tanδ measured within 30% of the thickness from the lower portion by more than 20%, and the relationship of the above formula (1) is satisfied, it is included in the present invention.

[0023] Furthermore, if the interface between different parts has a mixing part, etc., then the mixing part, etc., can be included as a part.

[0024] Furthermore, if the relationship in equation (1) above is satisfied, the surface of the constraint part opposite to the surface of the damping part 1 can have a portion having a tanδ value larger than tanδ1. Additionally, if the relationship in equation (1) above is satisfied, the surface of the damping part 2 opposite to the surface of the damping part 1 can have a portion having a tanδ value smaller than tanδ3.

[0025] [Constraints]

[0026] The restraining part of the present invention can be any of the following: an article rolled up like a film made of thermoplastic resin or the like, or a coating layer formed by coating on a support, but preferably in the form of a film.

[0027] The membrane used in the restraint section is preferably a resin membrane. Examples of resin materials constituting the resin membrane include polyester resins such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene naphthalate (PEN); polyolefin resins such as polyethylene and polypropylene; cellulose esters and their derivatives such as cellophane, cellulose diacetate, cellulose triacetate (TAC), cellulose acetate butyrate, cellulose acetate propionate (CAP), cellulose phthalate acetate, and cellulose nitrate; and polyvinylidene chloride, polyvinyl alcohol, and polyethylene glycol. Enols, syndiotactic polystyrene, polycarbonate (PC), norbornene resin, polymethylpentene, polyetherketone, polyimide (including transparent polyimide (CPI)), polyethersulfone (PES), polyphenylene sulfide, polysulfones, polyetherimide, polyetherketoneimide, polyamide, fluoropolymers, nylon, polymethyl methacrylate, polyarylates, ARTON (registered trademark, manufactured by JSR Corporation), apel (registered trademark, manufactured by Mitsui Chemicals Co., Ltd.) and other cyclic olefin resins, UV-curable or thermosetting acrylate resins, etc.

[0028] Among these resin materials, from the viewpoint of cost and ease of acquisition, polyethylene terephthalate (PET), cellulose diacetate, cellulose triacetate (TAC), transparent polyimide (CPI), or UV-curable or thermosetting acrylic resins are preferred.

[0029] The resin film mentioned above can be an unstretched film or a stretched film.

[0030] Resin films applicable to restraint parts can be manufactured using conventional film-making methods. For example, by melting the resin to be used as material using an extruder, extruding it using an annular die or a T-die, and then rapidly cooling it, a substantially amorphous and unoriented unstretched resin substrate can be produced. Alternatively, a stretched resin film can be manufactured by stretching the unstretched resin substrate in the resin substrate's transport direction (longitudinal axis, MD direction) or in a direction perpendicular to the resin substrate's transport direction (transverse axis, TD direction) using known methods such as uniaxial stretching, strut-type successive biaxial stretching, strut-type simultaneous biaxial stretching, and tubular simultaneous biaxial stretching. The stretch ratio can be appropriately selected based on the resin used as the raw material for the resin substrate, but is preferably in the range of 2 to 10 times in both the longitudinal and transverse directions.

[0031] In addition, the membrane used in the restraint section can be manufactured by solution casting.

[0032] If the thinning of the optical laminate is also considered, the thickness of the constraint portion is preferably 5 to 60 μm, more preferably 15 to 50 μm, and even more preferably 25 to 40 μm.

[0033] From the viewpoint of controlling tanδ, the weight-average molecular weight of the resin material used in the restraint section is preferably 5,000 to 4,000,000, more preferably 100,000 to 4,000,000. It should be noted that in this invention, the weight-average molecular weight (Mw) and number-average molecular weight (Mn) of the resin material can be determined by gel permeation chromatography (GPC) converted to polystyrene, and more specifically, by the method described in the examples.

[0034] From the viewpoint of heat resistance, the glass transition temperature of the restraint portion is preferably 70–170°C, more preferably 120–170°C. It should be noted that in this invention, the glass transition temperature can be determined from a DSC curve obtained by differential scanning calorimetry (DSC). More specifically, it is determined by extrapolating the glass transition onset temperature as described in JIS K 7121 (2012) "Method for determining the transition temperature of plastics".

[0035] From the viewpoint of impact resistance and flexural strength, the stored elastic modulus of the restraint portion is preferably 2.0 to 7.0 GPa, more preferably 4.0 to 7.0 GPa.

[0036] The tanδ(tanδ1) of the constraint part is not particularly restricted as long as it satisfies the relationship of the above formula (1), and is preferably 0.001 to 0.1, more preferably 0.01 to 0.05.

[0037] It should be noted that in this invention, the stored elastic modulus and tanδ of each part and each material are values ​​measured by a dynamic viscoelasticity measuring device, and more specifically, values ​​measured under the following test conditions. Furthermore, the tanδ of the restraint part, and the damping parts 1 and 2 described later, can be controlled by appropriately selecting the type of material used, the thickness of each part, etc.

[0038] The stored elastic modulus and tanδ of the restraint part and the damping part 1 were measured using a dynamic viscoelasticity measuring device (model: RSA-3) manufactured by TA Instruments Japan Co., Ltd., under the following test conditions at 25°C:

[0039] • Test conditions (dynamic viscoelasticity test)

[0040] Testing machine: Dynamic viscoelasticity measuring device (model: RSA-3) manufactured by TAInstruments Japan Co., Ltd.

[0041] Deformation method: stretching

[0042] Preload load: 55g

[0043] Temperature range: -70 to 200℃

[0044] Frequency: 1.0Hz

[0045] Displacement: ±0.1%

[0046] Sample: 5mm wide

[0047] Chuck pitch: 20mm.

[0048] In addition, the stored elastic modulus and tanδ of the damping section 2 were measured at 25°C using a nanoindentation device (model: G200XP) manufactured by Keysight Technologies under the following test conditions:

[0049] • Test conditions (dynamic viscoelasticity test)

[0050] Testing equipment: Keysight Technologies nanoindentation device (model: G200XP)

[0051] Deformation method: Press-fit

[0052] Temperature range: -100℃ to 100℃

[0053] Frequency: 1Hz

[0054] Displacement: 100nm

[0055] Sample size (shape, etc.): 10×10mm, thickness approximately 1mm.

[0056] It should be noted that, in order to measure the tanδ of each part of the optical laminate, the optical laminate can be subjected to a high temperature and high humidity environment, for example, to peel off each part and perform the measurement. Furthermore, if there are parts in the restraint part, damping part 1, and damping part 2 that are difficult to peel off, the part to be measured in the peeled part (e.g., damping part 1 and damping part 2) can be placed on top, and the same measurement used in damping part 2 can be performed to obtain the tanδ. Alternatively, the value of tanδ can be obtained by measuring either damping part 1 or damping part 2 according to the state of each part.

[0057] [Shock Absorption Unit 1]

[0058] The shock-absorbing part 1 of the present invention can be any of the following: a rolled-up article such as a film made of thermoplastic resin or the like, or a coating layer formed by coating the restraining part, but it is preferably in the form of a film. That is, both the restraining part and the shock-absorbing part 1 are preferably films.

[0059] There are no particular limitations on the materials included in the damping section 1. For example, thermoplastic (meth)acrylic resins, cyclic olefin resins, transparent polyurethane resins, and rubber materials such as graft copolymers can be used. From a flexibility viewpoint, the damping section 1 preferably includes at least a thermoplastic (meth)acrylic resin and a graft copolymer, or includes a transparent polyurethane resin, and is preferably a film containing at least a thermoplastic (meth)acrylic resin and a graft copolymer. It should be noted that in this specification, (meth)acrylic acid refers to the general term for acrylic acid and methacrylic acid.

[0060] The preferred range of the weight-average molecular weight of the resin material included in the damping section 1 varies depending on the type of material and cannot be generalized. For example, the preferred weight-average molecular weight of the resin material is 50 million to 4 million.

[0061] Hereinafter, thermoplastic (meth)acrylic resin, graft copolymer, cycloolefin resin and transparent polyurethane resin will be described as preferred materials for the damping part 1.

[0062] <Thermoplastic (meth)acrylic resins>

[0063] The weight-average molecular weight (Mw) of the thermoplastic (meth)acrylic resin is preferably 1 million or more. If the weight-average molecular weight of the thermoplastic (meth)acrylic resin is 1 million or more, the toughness of the resulting damping portion 1 can be improved. This prevents the damping portion 1 from breaking due to conveying tension. Furthermore, the storage modulus of elasticity of the damping portion 1 can also be increased, thus reducing the likelihood of winding deformation. From the same viewpoint, the weight-average molecular weight of the thermoplastic (meth)acrylic resin is more preferably 1.5 million to 3 million.

[0064] The weight-average molecular weight (Mw) of thermoplastic (meth)acrylic resins can be determined by gel permeation chromatography (GPC) to polystyrene. Specifically, it can be determined by the method described in the examples.

[0065] The thermoplastic (meth)acrylate resin preferably contains at least structural units derived from methyl methacrylate. From the viewpoint of improving the storage modulus of the damping portion 1 and enhancing the shelf life of the preferred film, the thermoplastic (meth)acrylate resin preferably further contains structural units derived from phenylmaleimide. Furthermore, from the viewpoint of improving brittleness by including this structural unit, it is more preferable to further contain structural units derived from alkyl acrylates.

[0066] That is, the thermoplastic (meth)acrylic resin preferably contains structural units derived from methyl methacrylate, structural units derived from phenylmaleimide, and structural units derived from alkyl acrylate.

[0067] The content of structural units derived from methyl methacrylate is preferably 50 to 95% by mass, more preferably 70 to 90% by mass, relative to all structural units constituting the thermoplastic (meth)acrylate resin.

[0068] The structural units derived from phenylmaleimide have a relatively rigid structure, which can improve the storage elastic modulus of the damping section 1. In addition, the structural units derived from phenylmaleimide have a large volume structure, which can have micropores in the resin matrix that allow the graft copolymer (rubber particles) to move, thus making it easy for the graft copolymer (rubber particles) to be biased towards the surface of the damping section 1.

[0069] The content of structural units derived from phenylmaleimide is preferably 1 to 25% by mass relative to all structural units constituting the thermoplastic (meth)acrylic resin. If the content of structural units derived from phenylmaleimide is 1% by mass or more, the storage elastic modulus of the damping portion 1 is easily increased; if it is 25% by mass or less, the brittleness of the damping portion 1 is less likely to be excessively damaged. From the above viewpoint, the content of structural units derived from phenylmaleimide is more preferably 7 to 15% by mass.

[0070] Structural units derived from alkyl acrylates can impart appropriate flexibility to the resin, thus improving, for example, the brittleness caused by the inclusion of structural units derived from phenylmaleimide.

[0071] Alkyl acrylates are preferably alkyl acrylates in which the alkyl moiety has 1 to 8 carbon atoms, more preferably 1 to 5. Examples of alkyl acrylates include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-hydroxyethyl acrylate, hexyl acrylate, and 2-ethylhexyl acrylate.

[0072] The content of structural units derived from alkyl acrylates is preferably 1 to 25% by mass relative to all structural units constituting the thermoplastic (meth)acrylate resin. If the content of structural units derived from alkyl acrylates is 1% by mass or more, the thermoplastic (meth)acrylate resin can be endowed with appropriate flexibility, so the damping part 1 will not become too brittle and is not easily broken. If the content of structural units derived from alkyl acrylates is 25% by mass or less, the Tg of the thermoplastic (meth)acrylate resin will not decrease excessively, so the heat resistance and storage modulus of elasticity of the damping part 1 will not decrease excessively. From the above viewpoint, the content of structural units derived from alkyl acrylates is more preferably 5 to 15% by mass.

[0073] The ratio of the structural unit from phenylmaleimide to the total amount of structural units from phenylmaleimide and structural units from alkyl acrylate is preferably 20 to 70% by mass. If this ratio is 20% by mass or more, the storage elastic modulus of the damping part 1 is easily increased, and if it is 70% by mass or less, the damping part 1 will not become too brittle.

[0074] The glass transition temperature (Tg) of the thermoplastic (meth)acrylic resin is preferably 100°C or higher, more preferably 120-150°C. If the Tg of the thermoplastic (meth)acrylic resin is within the above range, the heat resistance of the damping section 1 is easily improved. To adjust the Tg of the thermoplastic (meth)acrylic resin, for example, it is preferable to adjust the content of structural units from phenylmaleimide and structural units from alkyl acrylates.

[0075] <Graft copolymer (rubber particles)>

[0076] Graft copolymers (rubber particles) can impart toughness (softness) to the shock absorber 1.

[0077] Graft copolymers (rubber particles) are particles containing rubbery polymers. Rubbery polymers are soft, cross-linked polymers with a glass transition temperature below 20°C. Examples of such cross-linked polymers include butadiene-based cross-linked polymers, (meth)acrylic acid-based cross-linked polymers, and organosiloxane-based cross-linked polymers. From the viewpoint of having a small refractive index difference with thermoplastic (meth)acrylic acid-based resins and minimizing damage to the transparency of the damping portion 1, (meth)acrylic acid-based cross-linked polymers are preferred, and acrylic acid-based cross-linked polymers (acrylic rubbery polymers) are more preferred.

[0078] That is, the graft copolymer (rubber particles) is preferably composed of particles containing acrylic rubber-based polymers.

[0079] (Regarding acrylic rubber-based polymers (a))

[0080] Acrylic rubber-like polymer (a) is a crosslinked polymer containing structural units derived from acrylates as main components. Here, "containing as main components" means that the content of structural units derived from acrylates is within the range described later. Acrylic rubber-like polymer (a) is preferably a crosslinked polymer containing structural units derived from acrylates, structural units derived from other monomers that can copolymerize with them, and structural units derived from multifunctional monomers having two or more free radical polymerizable groups (non-conjugated reactive double bonds) in one molecule.

[0081] The preferred acrylates are alkyl acrylates with 1 to 12 carbon atoms, such as methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, sec-butyl acrylate, isobutyl acrylate, benzyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, and n-octyl acrylate. An acrylate can be used alone or in combination of two or more.

[0082] The content of structural units derived from acrylates is preferably 40 to 90% by mass, more preferably 50 to 80% by mass, relative to all structural units constituting the acrylic rubber polymer (a). If the content of acrylates is within the above range, it is easy to impart sufficient toughness to the protective film.

[0083] Other copolymerizable monomers are monomers other than polyfunctional monomers among those copolymerizable with acrylates. That is, the copolymerizable monomers do not have more than two free radical polymerizable groups. Examples of copolymerizable monomers include methacrylates such as methyl methacrylate; styrene-based monomers such as styrene and methylstyrene; (meth)acrylonitrile derivatives; (meth)acrylamide derivatives; and (meth)acrylic acid. Preferably, the other copolymerizable monomers include styrene-based monomers. There may be one or more other copolymerizable monomers.

[0084] The content of structural units from other copolymerizable monomers is preferably 5 to 55% by mass, more preferably 10 to 45% by mass, relative to all structural units constituting the acrylic rubber polymer (a).

[0085] Examples of multifunctional monomers include allyl (meth)acrylate, triallyl cyanurate, triallyl isocyanurate, diallyl phthalate, diallyl maleate, divinyl adipate, divinylbenzene, ethylene glycol di(meth)acrylate, diethylene glycol (meth)acrylate, triethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, tetramethylolmethane tetra(meth)acrylate, dipropylene glycol di(meth)acrylate, and polyethylene glycol di(meth)acrylate.

[0086] The content of structural units derived from multifunctional monomers is preferably 0.05 to 10% by mass, more preferably 0.1 to 5% by mass, relative to all structural units constituting the acrylic rubber polymer (a). If the content of multifunctional monomers is 0.05% by mass or more, the degree of crosslinking of the obtained acrylic rubber polymer (a) is easily increased, and the hardness and rigidity of the obtained damping part 1 are not excessively damaged. If it is 10% by mass or less, the toughness of the damping part 1 is not easily damaged.

[0087] The monomer composition of the acrylic rubber polymer (a) can be determined, for example, by using the peak area ratio detected by thermal decomposition GC-MS.

[0088] The glass transition temperature (Tg) of the acrylic rubber-like polymer (a) is preferably below 0°C, more preferably below -10°C. If the glass transition temperature (Tg) of the acrylic rubber-like polymer (a) is below 0°C, the film can be endowed with appropriate toughness. The glass transition temperature (Tg) of the acrylic rubber-like polymer (a) is determined by the same method as described above.

[0089] The glass transition temperature (Tg) of the acrylic rubber polymer (a) can be adjusted by the composition of the acrylic rubber polymer (a). For example, in order to lower the glass transition temperature (Tg) of the acrylic rubber polymer (a), it is preferable to increase the mass ratio of acrylates with 4 or more carbon atoms in the alkyl group to other copolymerizable monomers in the acrylic rubber polymer (a) (for example, to 3 or more, preferably 4 to 10).

[0090] The particles containing the acrylic rubbery polymer (a) can be particles composed of the acrylic rubbery polymer (a), or particles having a hard layer composed of a hard cross-linked polymer (c) with a glass transition temperature of 20°C or higher and a soft layer composed of the acrylic rubbery polymer (a) disposed therearound; or particles composed of an acrylic graft copolymer obtained by polymerizing at least one stage of a mixture of monomers such as methacrylate in the presence of the acrylic rubbery polymer (a). The particles composed of the acrylic graft copolymer can be core-shell type particles having a core containing the acrylic rubbery polymer (a) and a shell covering the core.

[0091] (Core-shell rubber particles containing acrylic rubber polymer (a))

[0092] (Nuclear Department)

[0093] The core comprises an acrylic rubber-like polymer (a), and may further comprise a rigid cross-linked polymer (c) if desired. That is, the core may have a soft layer composed of an acrylic rubber-like polymer (a) and a rigid layer composed of a rigid cross-linked polymer (c) disposed inside it.

[0094] The crosslinked polymer (c) can be a crosslinked polymer with methacrylate as the main component. That is, the crosslinked polymer (c) is preferably a crosslinked polymer containing structural units from alkyl methacrylate, structural units from other monomers that can be copolymerized with it, and structural units from multifunctional monomers.

[0095] Alkyl methacrylates can be the aforementioned alkyl methacrylates; other copolymerizable monomers can be the aforementioned styrene-based monomers, acrylates, etc.; multifunctional monomers can be the same monomers listed above as multifunctional monomers.

[0096] The content of structural units derived from alkyl methacrylates relative to all structural units constituting the crosslinked polymer (c) can be 40–100% by mass. The content of structural units derived from other copolymerizable monomers relative to all structural units constituting other crosslinked polymers (c) can be 60–0% by mass. The content of structural units derived from polyfunctional monomers relative to all structural units constituting other crosslinked polymers can be 0.01–10% by mass.

[0097] (Shell)

[0098] The shell portion preferably comprises a methacrylate polymer (b) (other polymers) grafted and bonded to an acrylic rubber polymer (a), which is mainly composed of structural units derived from methacrylates. "Main component" refers to the content of structural units derived from methacrylates, as described below.

[0099] The methacrylate constituting the methacrylate polymer (b) is preferably an alkyl methacrylate, such as methyl methacrylate, having 1 to 12 carbon atoms in the alkyl group. There may be one or more types of methacrylate.

[0100] The content of methacrylate is preferably 50% by mass or more relative to all structural units constituting the methacrylate polymer (b). If the content of methacrylate is 50% by mass or more, compatibility with methacrylate resins containing structural units derived from methyl methacrylate as the main component is readily obtained. From the above viewpoint, the content of methacrylate is more preferably 70% by mass or more relative to all structural units constituting the methacrylate polymer (b).

[0101] The methacrylate polymer (b) may further comprise structural units from other monomers that can copolymerize with methacrylates. Examples of other copolymerizable monomers include acrylates such as methyl acrylate, ethyl acrylate, and n-butyl acrylate; and (meth)acrylate monomers having alicyclic, heterocyclic, or aromatic rings, such as benzyl(meth)acrylate, dicyclopentanyl(meth)acrylate, and phenoxyethyl(meth)acrylate (including cyclic (meth)acrylate monomers).

[0102] The content of structural units derived from copolymerizable monomers is preferably 50% by mass or less, more preferably 30% by mass or less, relative to all structural units constituting the methacrylic polymer (b).

[0103] The grafting ratio (grafting rate) of the grafted component in the graft copolymer (rubber particles) is preferably 10 to 250% by mass, more preferably 15 to 150% by mass. If the grafting rate is above a certain level, the proportion of the grafted component, i.e., the methacrylic polymer (b) mainly composed of structural units derived from methacrylate, is appropriately high, thus easily improving the compatibility between the rubber particles and the methacrylic resin, making the rubber particles less prone to aggregation. In addition, the rigidity of the membrane is less likely to be damaged. If the grafting rate is below a certain level, the proportion of the acrylic rubber polymer (a) will not become too low, thus the improvement effect on the toughness and brittleness of the membrane is less likely to be compromised.

[0104] The grafting rate was determined by the following method.

[0105] 1) Dissolve 2g of core-shell particles in 50ml of methyl ethyl ketone and centrifuge (manufactured by Koki Holdings Co., Ltd., CP60E) at 30,000 rpm and 12°C for 1 hour to separate insoluble and soluble components (a total of 3 centrifugation operations).

[0106] 2) Substitute the weight of the obtained insoluble component into the following formula to calculate the grafting rate:

[0107] Grafting rate (mass%) = [{(mass of the insoluble component of methyl ethyl ketone) - (mass of acrylic rubber polymer (a))} / (mass of acrylic rubber polymer (a))] × 100.

[0108] There are no particular restrictions on the shape of the rubber particles, but a near-spherical shape is preferred. A near-spherical shape refers to a shape in which the aspect ratio of the rubber particles is approximately 1 to 2 when the cross-section or surface of the shock-absorbing part 1 is observed. In this way, the more spherical the rubber particles are, the more resistant they are to deformation of the laminate caused by contact with the rollers during conveying and internal stress during winding, and the easier it is to obtain resistance to deformation.

[0109] The average particle size of the graft copolymer (rubber particles) is preferably 100 to 400 nm. If the average particle size of the rubber particles is 100 nm or more, it is easier to impart sufficient toughness and stress relief to the damping part 1; if it is 400 nm or less, the transparency of the damping part 1 is less likely to be damaged. From the same point of view, the average particle size of the rubber particles is more preferably 150 to 300 nm.

[0110] The average particle size of the graft copolymer (rubber particles) can be calculated using the following method.

[0111] The average particle size of the graft copolymer (rubber particles) can be determined as the average of the equivalent circle diameters of 100 particles obtained by SEM or TEM photography of the surface or sections of the laminate. The equivalent circle diameter can be calculated by converting the projected area of ​​the particles obtained by photography into the diameter of a circle with the same area. In this case, rubber particles observed by SEM and / or TEM observation at 5000x magnification are used for the calculation of the average particle size.

[0112] When a film comprising at least a thermoplastic (meth)acrylic resin and a graft copolymer is used as the damping part 1, the content of the thermoplastic (meth)acrylic resin relative to the total mass of the film is preferably 5 to 95% by mass, more preferably 10 to 60% by mass, even more preferably 10 to 50% by mass, and particularly preferably 10 to 40% by mass.

[0113] When a film comprising at least a thermoplastic (meth)acrylic resin and a graft copolymer is used as the damping part 1, the content of the graft copolymer (rubber particles) relative to the total mass of the film is preferably 5 to 95% by mass, more preferably 40 to 90% by mass, even more preferably 50 to 90% by mass, and particularly preferably 60 to 90% by mass. If it is within this range, the size of the aggregates is sufficiently large and almost uniform, foreign matter is not easily mixed into the film, and a film with improved optical and mechanical properties can be obtained.

[0114] <Cycloolefin resins>

[0115] The cyclic olefin resin used in the shock-absorbing part 1 is preferably a polymer of cyclic olefin monomers or a copolymer of cyclic olefin monomers and other comonomers.

[0116] As a cyclic olefin monomer, a cyclic olefin monomer having a norbornene skeleton is preferred, and a cyclic olefin monomer having a structure represented by the following general formula (A-1) or (A-2) is more preferred.

[0117] General formula (A-1)

[0118]

[0119] In the above general formula (A-1), R 1 ~R 4 Each can independently represent a hydrogen atom, a hydrocarbon group with 1 to 30 carbon atoms, or a polar group. p represents an integer from 0 to 2. However, R... 1 ~R 4 All of them cannot simultaneously represent hydrogen atoms, R 1 and R 2 It will not simultaneously represent hydrogen atoms, R 3 and R 4 It cannot simultaneously represent hydrogen atoms.

[0120] As in the above general formula (A-1), R 1 ~R 4 The hydrocarbon group representing 1 to 30 carbon atoms is preferably a hydrocarbon group representing 1 to 10 carbon atoms, and more preferably a hydrocarbon group representing 1 to 5 carbon atoms. The hydrocarbon group representing 1 to 30 carbon atoms may further have a linking group comprising a halogen atom, an oxygen atom, a nitrogen atom, a sulfur atom, or a silicon atom. Examples of such linking groups include divalent polar groups such as carbonyl, imino, ether, silyl ether, and thioether. Examples of hydrocarbon groups representing 1 to 30 carbon atoms include methyl, ethyl, propyl, and butyl.

[0121] In the above general formula (A-1), R 1 ~R 4 Examples of polar groups include carboxyl, hydroxyl, alkoxy, alkoxycarbonyl, aryloxycarbonyl, amino, amide, and cyano. Among these, carboxyl, hydroxyl, alkoxycarbonyl, and aryloxycarbonyl are preferred, and from the viewpoint of ensuring solubility during solution film formation, alkoxycarbonyl and aryloxycarbonyl are preferred.

[0122] From the viewpoint of improving heat resistance, p in the above general formula (A-1) is preferably 1 or 2. This is because when p is 1 or 2, the resulting polymer volume increases, and the glass transition temperature is easily increased. In addition, it has the advantages of being able to respond slightly to humidity and easily controlling the curl balance as a laminate.

[0123] General formula (A-2)

[0124]

[0125] In the above general formula (A-2), R 5 R represents a hydrogen atom, a hydrocarbon group having 1 to 5 carbon atoms, or an alkylsilyl group having 1 to 5 carbon atoms. 6 This indicates a carboxyl, hydroxyl, alkoxycarbonyl, aryloxycarbonyl, amino, amide, cyano, or halogen atom (fluorine, chlorine, bromine, or iodine). p represents an integer from 0 to 2.

[0126] In the above general formula (A-2), R 5 Preferably, the hydrocarbon group represents 1 to 5 carbon atoms, and more preferably, the hydrocarbon group represents 1 to 3 carbon atoms.

[0127] In the above general formula (A-2), R 6 The preferred groups are carboxyl, hydroxyl, alkoxycarbonyl, and aryloxycarbonyl. From the viewpoint of ensuring solubility during solution film formation, alkoxycarbonyl and aryloxycarbonyl are more preferred.

[0128] From the perspective of improving heat resistance, p in the above general formula (A-2) is preferably 1 or 2. This is because when p is 1 or 2, the resulting polymer has a larger volume, and the glass transition temperature is more easily increased.

[0129] From the viewpoint of improving solubility in organic solvents, cyclic olefin monomers having the structure represented by the above general formula (A-2) are preferred. Generally, organic compounds exhibit reduced crystallinity by disrupting symmetry, thus increasing their solubility in organic solvents. R in general formula (A-2) 5 and R 6 The cyclic carbon atom is replaced only on one side of the symmetry axis of the molecule, so the symmetry of the molecule is low. That is, the cyclic olefin monomer with the structure represented by the general formula (A-2) has high solubility, so it is suitable for manufacturing the damping part 1 by solution casting.

[0130] Relative to the total amount of all cyclic olefin monomers constituting the cyclic olefin resin, the proportion of cyclic olefin monomers having the structure represented by general formula (A-2) in the polymer of cyclic olefin monomers is, for example, 70 mol% or more, preferably 80 mol% or more, and more preferably 100 mol%. If a certain amount or more of cyclic olefin monomers having the structure represented by general formula (A-2) is included, the orientation of the resin is improved, and therefore the phase difference (retardation) value tends to increase.

[0131] Hereinafter, specific examples of cyclic olefin monomers having a structure represented by general formula (A-1) are shown in Examples 1 to 14, and specific examples of cyclic olefin monomers having a structure represented by general formula (A-2) are shown in Examples 15 to 34.

[0132]

[0133] Examples of comonomers that can copolymerize with cyclic olefin monomers include comonomers that can undergo ring-opening copolymerization with cyclic olefin monomers and comonomers that can undergo addition copolymerization with cyclic olefin monomers.

[0134] Examples of comonomers that can undergo ring-opening copolymerization include cyclic olefins such as cyclobutene, cyclopentene, cycloheptene, cyclooctene, and dicyclopentadiene.

[0135] Examples of copolymerizable copolymerizable monomers include compounds containing unsaturated double bonds, vinyl cyclic hydrocarbon monomers, and (meth)acrylates. Examples of compounds containing unsaturated double bonds include olefinic compounds with 2 to 12 carbon atoms (preferably 2 to 8), such as ethylene, propylene, and butene. Examples of vinyl cyclic hydrocarbon monomers include vinylcyclopentene monomers such as 4-vinylcyclopentene and 2-methyl-4-isopropenylcyclopentene. Examples of (meth)acrylates include alkyl (meth)acrylates with 1 to 20 carbon atoms, such as methyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and cyclohexyl (meth)acrylate.

[0136] The proportion of cyclic olefin monomers in the copolymer of cyclic olefin monomers and copolymeric monomers can be, for example, 20 to 80 mol%, preferably 30 to 70 mol%, relative to the total number of monomers constituting the copolymer.

[0137] As described above, cyclic olefin resins are polymers obtained by polymerizing or copolymerizing cyclic olefin monomers having a norbornene backbone, preferably cyclic olefin monomers having a structure represented by the above general formula (A-1) or (A-2), and examples include the following:

[0138] 1) Ring-opening polymers of cyclic olefin monomers

[0139] 2) Ring-opening copolymers of cyclic olefin monomers and comonomers that can undergo ring-opening copolymerization with them

[0140] 3) Hydrogenates of the ring-opening (co)polymers of 1) or 2) above

[0141] 4) The (co)polymer obtained by cyclizing the ring-opening (co)polymer of 1) or 2) above through the Friedel-Crafts reaction followed by hydrogenation.

[0142] 5) Saturated copolymers of cyclic olefin monomers and compounds containing unsaturated double bonds

[0143] 6) Addition copolymers of cyclic olefin monomers and vinyl cyclic hydrocarbon monomers and their hydrides

[0144] 7) Alternating copolymers of cyclic olefin monomers and (meth)acrylates.

[0145] The polymers described in 1) to 7) above can all be obtained by known methods, such as those described in Japanese Patent Application Publication No. 2008-107534 and Japanese Patent Application Publication No. 2005-227606. For example, the catalyst and solvent used in the ring-opening copolymerization in 2) above can be those described in paragraphs 0019 to 0024 of Japanese Patent Application Publication No. 2008-107534. The catalyst used in the hydrogenation in 3) and 6) above can be those described in paragraphs 0025 to 0028 of Japanese Patent Application Publication No. 2008-107534. The acidic compound used in the Friedel-Crafts reaction in 4) above can be that described in paragraph 0029 of Japanese Patent Application Publication No. 2008-107534. The catalyst used in the addition polymerization of 5) to 7) above can be, for example, the catalyst described in paragraphs 0058 to 0063 of Japanese Patent Application Publication No. 2005-227606. The alternating copolymerization reaction of 7) above can be carried out, for example, by the method described in paragraphs 0071 to 0072 of Japanese Patent Application Publication No. 2005-227606.

[0146] Among these, polymers 1) to 3) and 5) are preferred, and polymers 3) and 5) are more preferred. That is, from the viewpoint that the glass transition temperature of the obtained resin can be increased and the light transmittance can be improved, the cyclic olefin resin preferably contains at least one of the structural units represented by the following general formula (B-1) and the structural units represented by the following general formula (B-2), more preferably it contains only the structural unit represented by general formula (B-2), or contains both the structural units represented by general formula (B-1) and the structural units represented by general formula (B-2). The structural unit represented by general formula (B-1) is a structural unit derived from the cyclic olefin monomer represented by the above general formula (A-1), and the structural unit represented by general formula (B-2) is a structural unit derived from the cyclic olefin monomer represented by the above general formula (A-2).

[0147] General formula (B-1)

[0148]

[0149] In the above general formula (B-1), X represents -CH=CH- or -CH2CH2-. 1 ~R 4 And p are respectively related to R in the above general formula (A-1) 1 ~R 4 It has the same meaning as p.

[0150] General formula (B-2)

[0151]

[0152] In the above general formula (B-2), X represents -CH=CH- or -CH2CH2-. 5 ~R 6 And p are respectively related to R in general formula (A-2) 5 ~R 6 It has the same meaning as p.

[0153] The cyclic olefin resins used in this invention can be commercially available. Examples of commercially available cyclic olefin resins include ARTON (ARTON (registered trademark, hereinafter the same)) G (e.g., G7810, etc.), ARTON F, ARTON R (e.g., R4500, R4900 and R5000, etc.) and ARTON RX (e.g., RX4500, etc.) manufactured by JSR Corporation.

[0154] The intrinsic viscosity [η]inh of the cyclic olefin resin is preferably 0.2–5 cm⁻¹ when measured at 30°C. 3 / g, more preferably 0.3-3cm 3 / g, more preferably 0.4–1.5cm 3 / g.

[0155] The number-average molecular weight (Mn) of the cyclic olefin resin is preferably 8,000 to 100,000, more preferably 10,000 to 80,000, and even more preferably 12,000 to 50,000. The weight-average molecular weight (Mw) of the cyclic olefin resin is preferably 20,000 to 300,000, more preferably 30,000 to 250,000, and even more preferably 40,000 to 200,000.

[0156] If the intrinsic viscosity [η]inh, number-average molecular weight, and weight-average molecular weight are within the above ranges, the heat resistance, water resistance, chemical resistance, mechanical properties, and processability of the cyclic olefin resin as a substrate film become good.

[0157] The glass transition temperature (Tg) of cycloolefin resins is typically above 110°C, preferably 110–350°C, more preferably 120–250°C, and even more preferably 120–220°C. If the Tg is above 110°C, deformation under high-temperature conditions is easily suppressed. On the other hand, if the Tg is below 350°C, molding and processing become easier, and resin degradation caused by heat during molding and processing is also easily suppressed.

[0158] The content of cyclic olefin resin relative to the total mass of the damping part 1 is preferably 70% by mass or more, and more preferably 80% by mass or more.

[0159] <Particles>

[0160] When the shock-absorbing part 1 of the present invention contains cyclic olefin resin, it is even more preferable to further contain particulate matter.

[0161] Examples of inorganic compounds used as particulate matter include silica, titanium dioxide, alumina, zirconium oxide, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, and calcium phosphate. Alternatively, particulate matter of organic compounds may be preferred. Examples of organic compounds include pulverized and graded products of organic polymers such as polytetrafluoroethylene, cellulose acetate, polystyrene, polymethyl methacrylate, polypropyl methacrylate, polymethyl acrylate, polyethylene carbonate, styrene-based acrylic resins, silicone resins, polycarbonate resins, benzoguanamine resins, melamine resins, polyolefin powders, polyester resins, polyamide resins, polyimide resins, or polyvinyl fluoride resins, starch, etc., as well as polymers synthesized by suspension polymerization.

[0162] From the viewpoint of reducing turbidity, the microparticles preferably contain silicon, and more preferably silicon dioxide. Examples of such microparticles include those commercially available under the trade names AEROSIL (registered trademark, hereinafter the same) R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, and TT600 (all manufactured by AEROSIL Co., Ltd. of Japan), which can be used.

[0163] <Transparent polyurethane resin>

[0164] The transparent polyurethane resin used in the shock-absorbing section 1 is preferably formed from a polyurethane resin forming composition.

[0165] The polyurethane resin-forming composition of the present invention comprises a polyisocyanate (A) and a polyol (B). Either or both of the polyisocyanate (A) or the polyol (B) contain ethylene oxide units, and the content of the ethylene oxide units is preferably 3 to 15% by mass, more preferably 3 to 10% by mass, relative to the total amount of (A) and (B).

[0166] As a method for introducing ethylene oxide units, they can be introduced by using a polyether compound (b) having terminal active hydrogen functional groups and having an average of more than 6 ethylene oxide units per molecule and pre-carbamate a portion of the polyisocyanate (A), or by mixing it in a polyol (B) and carbamate it during curing.

[0167] Polyether Compounds (b)

[0168] The polyether compound (b) used in this invention is a compound having terminal active hydrogen functional groups such as hydroxyl and amino groups and having an average of more than 6 ethylene oxide units per molecule. Examples of polyether compounds (b) used in this invention include alkyl oxide adducts of alcohols, phenols, and amines.

[0169] As an epoxy alkane, ethylene oxide (hereinafter referred to as EO), propylene oxide (hereinafter referred to as PO), and tetrahydrofuran (hereinafter referred to as THF) can be used as essential components and then combined in any way. However, when epoxy alkane other than EO is used in combination, in order to improve the whitening resistance of the obtained polyurethane resin, it is necessary to increase the amount of polyether compound (b), which leads to the deterioration of weather resistance. Therefore, it is preferable to use EO alone.

[0170] Examples of the aforementioned alcohols include water, monohydric alcohols (methanol, ethanol, propanol, butanol, pentanol, hexanol, heptanol, octanol, nonanol, decanol, etc.), dihydric alcohols (ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,3-butanediol, neopentyl glycol, etc.), trihydric alcohols (glycerol, trimethylolpropane, etc.), 4- to 8-hydric alcohols (pentaerythritol, diglycerol, α-methylglucoside, sorbitol, xylitol, mannitol, glucose, fructose, sucrose, etc.), and combinations of two or more of them.

[0171] Examples of the aforementioned phenols include hydroquinone, bisphenols (bisphenol A, bisphenol F, etc.), formalin low-condensity condensates of phenolic compounds (number average molecular weight less than 1000) (intermediates of phenolic varnish resins and resorcinol), and combinations of two or more of them.

[0172] Examples of the aforementioned amines include ammonia, alkanolamines (monoethanolamine, diethanolamine, triethanolamine, isopropanolamine, aminoethylethanolamine, etc.), alkylamines with 1 to 20 carbon atoms (methylamine, ethylamine, n-butylamine, octylamine, etc.), alkylene diamines with 2 to 6 carbon atoms (ethylenediamine, hexamethylenediamine, etc.), polyalkylene polyamines with 2 to 6 carbon atoms (degree of polymerization 2 to 8) (diethylenetriamine, triethylenetetramine, etc.), aromatic amines with 6 to 20 carbon atoms (aniline, phenylenediamine, diaminotoluene, phenylenediamine, methylenediphenylamine, diphenyl ether diamine, etc.), alicyclic amines with 4 to 15 carbon atoms (isophorone diamine, cyclohexanediamine, etc.), heterocyclic amines with 4 to 15 carbon atoms (aminoethylpiperazine), and combinations of two or more of them.

[0173] Polyisocyanate (A)

[0174] The polyisocyanate (A) used in this invention may include aliphatic and / or alicyclic diisocyanate monomers (a1) and isocyanurate bodies, urea carbamate bodies, adducts, prepolymers, etc. derived therefrom, and one or more of them may be used alone or in combination.

[0175] Examples of aliphatic and / or alicyclic diisocyanate monomers (a1) include hexamethylene diisocyanate, tetramethylene diisocyanate, 2-methyl-pentane-1,5-diisocyanate, 3-methyl-pentane-1,5-diisocyanate, lysine diisocyanate, trioxide diisocyanate, isophorone diisocyanate, cyclohexyl diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, norbornene diisocyanate, hydrogenated toluene diisocyanate, hydrogenated naphthalene diisocyanate, hydrogenated xylene diisocyanate, and hydrogenated tetramethylxylene diisocyanate. These aliphatic and / or alicyclic diisocyanates can be used alone or in combination of two or more. In this embodiment, from the viewpoint of physical properties, durability, and practicality, hexamethylene diisocyanate, isophorone diisocyanate, and 4,4′-dicyclohexylmethane diisocyanate are preferred, with hexamethylene diisocyanate being particularly preferred.

[0176] When using isocyanurate, urethane, or adduct as polyisocyanate (A), it is preferable to remove unreacted isocyanate monomers to a residual content of less than 1.0% by mass through processes such as distillation. Furthermore, by pre-carbamate the aforementioned polyisocyanate with the polyether compound (b), EO units can be incorporated into the polyisocyanate (A).

[0177] The average number of NCO functional groups in the polyisocyanate (A) is preferably in the range of 2.5 to 5.0, and more preferably in the range of 3.0 to 4.5.

[0178] Polyols (B)

[0179] Examples of polyols (B) used in this invention include polycarbonate polyols, polyester polyols, polycaprolactone polyols, and polyether polyols.

[0180] Examples of polycarbonate-based polyols used in this invention include those obtained by polycondensation of short-chain polyols such as ethylene glycol, 1,2-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, diethylene glycol, dipropylene glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, 3-methyl-1,5-pentanediol, neopentanediol, 1,6-hexanediol, 2,2-dimethylolheptane, glycerol, and trimethylolpropane with low-molecular-weight carbonates such as ethylene carbonate, dimethyl carbonate, diethyl carbonate, and diphenyl carbonate. Copolycarbonate polyols obtained by polycondensation of two or more of the above-mentioned short-chain polyols with low-molecular-weight carbonates may also be used. Furthermore, mixtures of the above-mentioned polycarbonate-based polyols may also be used.

[0181] Examples of polyester polyols used in this invention include those obtained by polycondensation of the aforementioned short-chain polyols with polycarboxylic acids such as adipic acid, succinic acid, malonic acid, pimelic acid, sebacic acid, and trimellitic acid. Copolyester polyols obtained by polycondensation of two or more of the aforementioned short-chain polyols with polycarboxylic acids may also be used. Furthermore, mixtures of the aforementioned polyester polyols may also be used.

[0182] Examples of polycaprolactone-based polyols used in this invention include those obtained by using the aforementioned short-chain polyols as initiators and performing ring-opening addition reactions with cyclic esters such as ε-caprolactone, β-butyrolactone, γ-butyrolactone, γ-valerolactone, and δ-valerolactone. Alternatively, mixtures of the aforementioned polycaprolactone-based polyols may also be used.

[0183] Examples of polyether-based polyols used in this invention include poly(vinyl ether) glycol, poly(propylene ether) glycol, and polytetramethylene ether glycol, obtained by ring-opening polymerization of the aforementioned short-chain polyols with cyclic ethers such as EO, PO, and THF. Copolymers of polyether-based polyols utilizing two or more of the aforementioned cyclic ethers can also be used. Furthermore, mixtures of these polyether-based polyols can also be used.

[0184] As polyol (B), the polycarbonate-based polyols, polyester-based polyols, polycaprolactone-based polyols, and polyether-based polyols mentioned above can be used alone or in combination of two or more. From the viewpoint of the weather resistance of the resulting polyurethane resin, polycarbonate-based polyols, polyester-based polyols, and polycaprolactone-based polyols are preferred. When using polyether-based polyols, since weather resistance deteriorates, it is preferable to use them in the minimum necessary amount. Furthermore, the aforementioned polyether compound (b) can also be used as an EO unit source.

[0185] Furthermore, as polyol (B), a polyol with an average OH functional group number of 3 or more can be used as a crosslinking agent. Examples of polyols with an average OH functional group number of 3 or more used as crosslinking agents in this invention include triols such as glycerol, trimethylolpropane, di(trimethylolpropane), diglycerol, and pentaerythritol, which can be used alone or in combination of two or more.

[0186] Furthermore, diols, which are polyols (B), can be used as chain extenders. Examples of diols used as chain extenders in this invention include ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, octanediol, nonanediol, decanediol, diethylene glycol, dipropylene glycol, 1,4-cyclohexyldiethanol, hydroquinone-bis-(2-hydroxyethyl) ether (including various isomers), etc., and one or more of them can be used alone or in combination.

[0187] The hydroxyl value of the polyol (B) is preferably 300 mg KOH / g to 700 mg KOH / g, more preferably 400 mg KOH / g to 600 mg KOH / g. Furthermore, the average number of OH functional groups in the polyol (B) is preferably 2.1 to 3.0.

[0188] <Catalyst>

[0189] In this invention, a carbamate catalyst can be used in the process of reacting polyisocyanate (A) with polyol (B) to obtain polyurethane resin. Known carbamate catalysts include amine compounds (e.g., triethylenediamine), organometallic compounds (e.g., dibutyltin dilaurate), and quaternary ammonium salts; however, from the viewpoint of coloring the obtained polyurethane resin, an organometallic compound is preferred. From a workability perspective, the catalyst is preferably pre-mixed in the polyol (B).

[0190] Polyurethane resin forming compositions can be appropriately formulated with additives such as antioxidants, ultraviolet absorbers, flame retardants, hydrolysis inhibitors, lubricants, plasticizers, fillers, antistatic agents, dispersants, and storage stabilizers as needed.

[0191] Manufacturing Method of Polyurethane Resin

[0192] The polyurethane resin obtained using the above-described polyurethane resin forming composition is manufactured, for example, by the following method.

[0193] After degassing and heat preservation in different tanks of a two-liquid urethane casting machine, the polyisocyanate (A) and polyol (B) are mixed in a specified ratio in the mixer section. The mixture discharged from the casting machine is then injected into a mold with a temperature adjusted to 50–150°C. Once a demoldable green body strength is achieved, the cured material is removed from the mold. Generally, demolding occurs within approximately 5–60 minutes. After two curing cycles as needed, the material is often further processed and assembled into equipment as an optical component.

[0194] As a method for forming sheets without using molds, the following method can be cited: the mixture discharged from the casting machine is continuously spread on a release film such as PET film, the release film is covered on the other side before the resin cures, the thickness is made uniform by using rollers, scrapers, etc., and then the sheet is rolled up by rollers in a curing oven heated to 50-150°C.

[0195] There are no particular limitations on the manufacturing method (forming method) of the damping part 1, but the preferred method is to obtain the damping part 1 in the form of a film by preparing a coating (dope) containing a resin material or rubber material, a solvent and any other components, applying the coating to a substrate, and then drying it.

[0196] When a transparent polyurethane resin is used as the shock-absorbing part 1, it is preferable to use a polyurethane resin film obtained by the manufacturing method (forming method) described in the above-mentioned "Method for Manufacturing Polyurethane Resin".

[0197] Next, the manufacturing method of the shock-absorbing part 1 when using coating will be explained.

[0198] <Solvent>

[0199] The solvents used in coatings are not particularly limited as long as they can effectively disperse the resin or rubber materials. Examples of solvents include alcohols such as methanol, ethanol, propanol, n-butanol, 2-butanol, tert-butanol, and cyclohexanol; ketones such as methyl ethyl ketone (MEK), methyl isobutyl ketone, and acetone; esters such as ethyl acetate, methyl acetate, ethyl lactate, isopropyl acetate, amyl acetate, and ethyl butyrate; tetrahydrofuran (THF); and 1,4-di(ethyl butyrate). Alkyl ethers, glycol ethers (propylene glycol mono(C1-C4)alkyl ethers (specifically propylene glycol monomethyl ether (PGME), propylene glycol monoethyl ether, propylene glycol mono-n-propyl ether, propylene glycol monoisopropyl ether, propylene glycol monobutyl ether, etc.), propylene glycol mono(C1-C4)alkyl ether esters (propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate)), toluene, benzene, cyclohexane, n-hexane, and other hydrocarbons. These solvents can be used alone or in combination of two or more. Among them, methyl ethyl ketone, ethyl acetate, acetone, and tetrahydrofuran are preferred from the viewpoints of easy dissolution of resin materials, low boiling point, and easy improvement of drying speed and productivity. It should be noted that dichloromethane or other solvents can be further mixed into the solvents listed above.

[0200] From the viewpoint of easy viscosity adjustment, the concentration of solid components in the coating is preferably, for example, 5 to 20% by mass.

[0201] <Other Ingredients>

[0202] The coatings described above may be further supplemented with other ingredients not mentioned above, as needed. Examples of other ingredients include matting agents (microparticles), UV absorbers, surfactants, etc.

[0203] From the perspective of imparting slip properties to the film, matting agents can be added. Examples of matting agents include inorganic particles such as silica particles and organic particles with a glass transition temperature above 80°C.

[0204] Examples of ultraviolet absorbers include benzotriazole-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, and triazine-based ultraviolet absorbers.

[0205] Examples of surfactants include anionic surfactants such as carboxylic acid type, sulfonic acid type, sulfate ester type, and phosphate ester type; cationic surfactants such as alkylamine salt type and quaternary ammonium salt type; and any of the following amphoteric surfactants: carboxybetaine type, 2-alkylimidazoline derivative type, glycine type, and amine oxide type.

[0206] <Paint Making>

[0207] The above-mentioned resin material, solvent, and any other components contained herein are mixed under nitrogen atmosphere while stirring as needed to prepare a coating.

[0208] There are no particular restrictions on the order in which the components of the coating are mixed. There are also no particular restrictions on the method of mixing the components; for example, a mixer can be used.

[0209] There are no particular limitations on the mixing time (stirring time), but it can be, for example, 1 to 10 hours. Similarly, there are no particular limitations on the mixing temperature (stirring temperature), but it can be, for example, 20 to 50°C.

[0210] The viscosity of the coating is not particularly limited as long as it is sufficient to form the damping portion 1 of the desired thickness, but is preferably, for example, 5 to 5000 mPa·s. If the viscosity of the coating is 5 mPa·s or higher, it is easy to form the damping portion 1 of appropriate thickness; if it is 5000 mPa·s or lower, uneven thickness caused by an increase in the viscosity of the solution can be suppressed. From the same point of view, the viscosity of the coating is more preferably 100 to 1000 mPa·s. It should be noted that the viscosity of the coating can be measured using an E-type viscometer at 25°C.

[0211] The resulting coating can be filtered as needed. There are no particular restrictions on the filtration method; previously known methods can be appropriately used.

[0212] [The film-making process]

[0213] The coating obtained as described above is applied to the surface of the substrate. Then, a film is formed by removing the solvent from the coating, thus forming a film (laminated body) comprising the substrate and the damping portion 1. Hereinafter, the process of applying the coating to the substrate and the process of forming the damping portion 1 (drying process) will be described.

[0214] (Regarding the process of applying coatings)

[0215] In this process, the coating obtained as described above is applied to the surface of the substrate. Specifically, the coating is applied to the surface of the substrate.

[0216] <Substrate>

[0217] The substrate only needs to be able to support the shock-absorbing part 1, and there are no special restrictions, but it can usually contain a resin film.

[0218] Examples of resin films include polyester resin films (such as polyethylene terephthalate (PET), polypropylene terephthalate (PTT), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polybutylene naphthalate (PBN), etc.), cyclic olefin resin films (COP), acrylic films, and cellulose resin films (such as cellulose triacetate films (TAC), etc.). From the viewpoint of versatility and high tensile modulus, PET films, cellulose triacetate films (TAC), and cyclic olefin resin films are preferred.

[0219] Resin films can be thermally relaxed or stretched.

[0220] By thermally relaxing the resin film, both crystallinity and orientation can be reduced, thus lowering the tensile modulus of elasticity of the resin film and even the substrate. There is no particular limitation on the thermal relaxation temperature, but if the glass transition temperature of the resin constituting the resin film is set as Tg, it can be performed at (Tg+60) to (Tg+180) °C. Thermal relaxation can be performed before or after the formation of the release layer.

[0221] Stretching treatment increases the orientation of resin molecules by stretching the resin film, thereby improving the tensile modulus of elasticity of the resin film and even the substrate. Stretching treatment can be performed, for example, in one or both axial directions of the substrate. It can be performed under any conditions, for example, at a stretch ratio of approximately 120–900%. The stretch ratio is the value obtained by multiplying the stretch ratios in each direction. Whether a resin film has been stretched (whether it is a stretched film) can be determined, for example, by whether it has an in-plane slow axis (an axis extending in the direction of maximum refractive index).

[0222] The substrate preferably further has a release layer disposed on the surface of the resin film. The release layer allows the shock-absorbing part 1 to be easily peeled off from the substrate.

[0223] The release layer may contain known release agents or mold release agents, without particular limitation. Examples of release agents contained in the release layer include silicone-based release agents and non-silicone-based release agents.

[0224] Examples of silicone-based release agents include well-known silicone resins. Examples of non-silicone-based release agents include long-chain alkyl draping polymers obtained by reacting long-chain alkyl isocyanates with polyvinyl alcohol or ethylene-vinyl alcohol copolymers, olefin resins (e.g., copolymer polyethylene, cyclic polyolefins, polymethylpentene), polyaryl resins (e.g., condensation polymers of aromatic dicarboxylic acid components and diphenol components), fluoropolymers (e.g., polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), PFA (a copolymer of tetrafluoroethylene and perfluoroalkoxyethylene), FEP (a copolymer of tetrafluoroethylene and hexafluoropropylene), ETFE (a copolymer of tetrafluoroethylene and ethylene)), etc.

[0225] The release layer may further include additives as needed. Examples of additives include fillers, lubricants (waxes, fatty acid esters, fatty acid amides, etc.), stabilizers (antioxidants, heat stabilizers, light stabilizers, etc.), flame retardants, viscosity modifiers, thickeners, defoamers, and UV absorbers.

[0226] The thickness of the release layer is not particularly limited as long as it can exhibit the desired degree of peelability, but is preferably 0.1 to 1.0 μm.

[0227] There is no particular limitation on the thickness of the substrate, but it is preferably 10 to 100 μm, and more preferably 25 to 50 μm.

[0228] There are no particular restrictions on the coating method; for example, known methods such as back coating, gravure coating, spin coating, wire rod coating, and roller coating can be used. Among these, back coating is preferred from the viewpoint that it can form a thin and uniform coating film.

[0229] (Regarding the process of forming the vibration damping part 1)

[0230] Next, the solvent is removed from the coating applied to the substrate to form the damping part 1.

[0231] Specifically, the coating applied to the substrate is dried. Drying can be carried out, for example, by air supply or heating. From the viewpoint of easily suppressing curling of the laminate, drying by air supply is preferred.

[0232] By adjusting the drying conditions (e.g., drying temperature, solvent concentration in the atmosphere, drying time, etc.), the residual solvent content in the dried coating film, i.e., the damping section 1, is kept below a certain level. Furthermore, the distribution of the graft copolymer (rubber particles) in the damping section 1 can be adjusted according to the drying conditions. Specifically, from the viewpoint of preventing the graft copolymer (rubber particles) from becoming concentrated, it is preferable to use a solvent with good affinity for the graft copolymer (rubber particles), and to increase the drying temperature and preferably decrease the solvent concentration in the atmosphere.

[0233] When the boiling point of the solvent is set to Tb (°C), the drying temperature is preferably (Tb-50)~(Tb+50)°C, more preferably (Tb-40)~(Tb+40)°C. If the drying temperature is above the lower limit, the evaporation rate of the solvent can be increased, thus making it easier for the graft copolymer (rubber particles) to become biased. If it is below the upper limit, the solvent concentration in the atmosphere can be prevented from becoming too high. For example, when using a mixed solvent of acetone / methanol, the drying temperature can be 40°C or higher.

[0234] The solvent concentration in the drying atmosphere is preferably 0.10 to 0.30% by mass, more preferably 0.10 to 0.20% by mass. If the solvent concentration in the atmosphere is 0.10% by mass or more, the solvent will not evaporate excessively, and therefore the coating film is less prone to cracking. If the solvent concentration is 0.30% by mass or less, it is easy to appropriately increase the evaporation rate of the solvent from the coating film, thus making it easier for rubber particles to adhere to the surface. The solvent concentration in the atmosphere can be adjusted by the drying temperature and the dew point temperature inside the drying oven. Furthermore, the solvent concentration in the atmosphere can be measured using an infrared gas concentration meter.

[0235] If the substrate is peeled off from the laminate of the substrate and the damping part 1 obtained in this way, a film-like damping part 1 can be obtained.

[0236] According to one embodiment of the present invention, the in-plane phase difference (R0) of the damping part 1, expressed by the following formula (A), is preferably -10 to 10 nm.

[0237] R0=(Nx-Ny)×d (A)

[0238] In the above formula (A), Nx is the refractive index in the maximum direction in the plane of the damping part 1, Ny is the minimum refractive index in the plane of the damping part 1, and d is the thickness of the damping part 1.

[0239] The in-plane phase difference (R0) can be measured using an automatic birefringence meter. For example, it can be determined using an automatic birefringence meter KOBRA-21ADH (manufactured by Oji Measurement Equipment Co., Ltd.) at a wavelength of 590 nm in an environment with a temperature of 23°C and a humidity of 55%RH.

[0240] If the thinning of the optical laminate is also considered, the thickness of the damping part 1 is preferably 10 to 60 μm, more preferably 15 to 50 μm, and even more preferably 25 to 40 μm.

[0241] From the viewpoint of impact resistance, the glass transition temperature of the damping part 1 is preferably -30°C to 180°C. It should be noted that if multiple glass transition temperatures are observed when measuring the glass transition temperature of the damping part 1, the lowest glass transition temperature measured shall be taken as the glass transition temperature of the damping part 1.

[0242] From the viewpoint of impact resistance and flexural strength, the stored elastic modulus of the damping part 1 is preferably 0.1 to 3.0 GPa, more preferably 0.1 to 1.0 GPa.

[0243] The tanδ (tanδ2) of the damping part 1 is not particularly limited as long as it satisfies the relationship of the above formula (1), but it is preferably 0.01 to 0.3, and more preferably 0.05 to 0.3.

[0244] According to a preferred embodiment of the present invention, when the stored elastic modulus of the restraint part is set as elastic modulus 1 (unit: GPa) and the stored elastic modulus of the damping part 1 is set as elastic modulus 2 (unit: GPa), elastic modulus 1 and elastic modulus 2 preferably satisfy the relationship of the following equation (2). By satisfying the relationship of the following equation (2), the effects of the present invention can be more effectively exerted.

[0245] Elastic modulus 1 / Elastic modulus 2 > 8(2)

[0246] It should be noted that an adhesive portion may be provided between the aforementioned restraint portion and the damping portion 1. There are no particular limitations on the materials used in such an adhesive portion; examples include rubber-based adhesives, acrylic-based adhesives, silicone-based adhesives, polyurethane-based adhesives, vinyl alkyl ether-based adhesives, polyvinyl alcohol-based adhesives, polyvinylpyrrolidone-based adhesives, polyacrylamide-based adhesives, and cellulose-based adhesives. More specific examples include the adhesive layer obtained by irradiating an active energy ray-curable adhesive material with active energy rays, as disclosed in Japanese Patent Application Publication No. 2009-242633.

[0247] [Shock Absorber 2]

[0248] The shock-absorbing part 2 of the present invention can be any of the following: an article rolled up like a film made of thermoplastic resin or the like, or a coating layer formed by coating the shock-absorbing part 1, but preferably in the form of a coating layer.

[0249] There are no particular limitations on the materials constituting the damping part 2, but it is preferable to use an adhesive. There are no particular limitations on the type of adhesive; examples include rubber-based adhesives, acrylic adhesives, silicone adhesives, polyurethane adhesives, vinyl alkyl ether adhesives, polyvinyl alcohol adhesives, polyvinylpyrrolidone adhesives, polyacrylamide adhesives, and cellulose adhesives. Among these adhesives, acrylic adhesives are preferred from the viewpoints of excellent transparency, appropriate adhesion, cohesiveness, and bonding properties, as well as excellent weather resistance and heat resistance. Acrylic adhesives contain an acrylic polymer as the base polymer.

[0250] The damping part 2 using an acrylic adhesive is preferably formed by ultraviolet polymerization of an ultraviolet-curable acrylic adhesive composition containing a monomer component containing an alkyl methacrylate and / or a portion of the polymer of that monomer component, an ultraviolet absorber, and a photopolymerization initiator having an absorption band at a wavelength of 400 nm or higher.

[0251] Alkyl methacrylates can be exemplified by having a straight-chain or branched alkyl group with 1 to 24 carbon atoms at the ester terminus. Alkyl methacrylates can be used alone or in combination of two or more. It should be noted that alkyl methacrylates are a general term for alkyl acrylates and alkyl methacrylates.

[0252] Examples of alkyl (meth)acrylates include, for instance, alkyl (meth)acrylates having straight-chain or branched alkyl groups having 4 to 9 carbon atoms. Specifically, examples include n-butyl (meth)acrylate, sec-butyl (meth)acrylate, tert-butyl (meth)acrylate, isobutyl (meth)acrylate, n-pentyl (meth)acrylate, isopentyl (meth)acrylate, isohexyl (meth)acrylate, isoheptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, isooctyl (meth)acrylate, and isononyl (meth)acrylate. They can be used alone or in combination of two or more.

[0253] Relative to the total mass of the monofunctional monomer components forming the (meth)acrylic polymer, the alkyl (meth)acrylic ester having an alkyl group having 1 to 24 carbon atoms at the ester end is preferably 40% by mass or more, more preferably 50% by mass or more, and even more preferably 60% by mass or more.

[0254] The monomer composition may contain comonomers other than alkyl (meth)acrylates as monofunctional monomer components. The comonomers may be used as the remainder of the alkyl (meth)acrylate in the monomer composition.

[0255] Examples of comonomers include cyclic nitrogen monomers. Among cyclic nitrogen monomers, monomers having polymerizable functional groups with unsaturated double bonds, such as (meth)acryloyl or vinyl groups, and having a cyclic nitrogen structure can be used without particular limitation. Preferably, the cyclic nitrogen structure contains nitrogen atoms within the ring structure. Examples of cyclic nitrogen monomers include lactam vinyl monomers such as N-vinyl-2-pyrrolidone, N-vinyl-ε-caprolactam, and methylvinylpyrrolidone; vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazolium, vinylpyrrole, vinylimidazole, and vinyl... Vinyl monomers containing nitrogen-containing heterocycles, such as azoles and vinylmorpholine, are examples. Additionally, (meth)acrylic acid monomers containing heterocycles such as morpholine rings, piperidine rings, pyrrolidine rings, and piperazine rings can be cited. Specifically, N-acryloylmorpholine, N-acryloylpiperidine, N-methacryloylpiperidine, and N-acryloylpyrrolidine are examples. Among these cyclic nitrogen monomers, lactam-based vinyl monomers are preferred.

[0256] In this invention, the cyclic nitrogen-containing monomer is preferably 0.5 to 50% by mass, more preferably 0.5 to 40% by mass, and even more preferably 0.5 to 30% by mass, relative to the total mass of the monofunctional monomer components forming the (meth)acrylic polymer.

[0257] The monomer components used in this invention may include hydroxyl-containing monomers as monofunctional monomer components. As hydroxyl-containing monomers, monomers having polymerizable functional groups such as (meth)acryloyl or vinyl groups with unsaturated double bonds and possessing hydroxyl groups can be used without particular limitation. Examples of hydroxyl-containing monomers include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate, and other hydroxyalkyl (meth)acrylate esters; and hydroxyalkylcycloalkane (meth)acrylate esters such as (4-hydroxymethylcyclohexyl)meth(meth)acrylate. Other examples include hydroxyethyl (meth)acrylamide, allyl alcohol, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, and diethylene glycol monovinyl ether. They can be used alone or in combination of two or more. Among them, hydroxyalkyl (meth)acrylates are preferred.

[0258] The content of hydroxyl-containing monomers is preferably 1% by mass or more, more preferably 2% by mass or more, and even more preferably 3% by mass or more, relative to the total mass of the monofunctional monomer components forming the (meth)acrylic polymer. On the other hand, if there is too much hydroxyl-containing monomer, the damping portion 2 becomes hard, and sometimes the adhesive strength decreases. In addition, since the viscosity of the adhesive sometimes becomes too high or gels, the content of hydroxyl-containing monomers is preferably 30% by mass or less, more preferably 27% by mass or less, and even more preferably 25% by mass or less, relative to the total amount of the monofunctional monomer components forming the (meth)acrylic polymer.

[0259] In addition, the monomer components that form (meth)acrylic polymers may contain monomers with other functional groups as monofunctional monomers, such as monomers containing carboxyl groups or monomers with cyclic ether groups.

[0260] As a carboxyl-containing monomer, any monomer having a polymerizable functional group such as (meth)acryloyl or vinyl with an unsaturated double bond and a carboxyl group can be used without particular restriction. Examples of carboxyl-containing monomers include (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid. They can be used alone or in combination of two or more. Itaconic acid or maleic acid can also be used with their anhydrides. Acrylic acid and methacrylic acid are preferred, with acrylic acid being particularly preferred. It should be noted that carboxyl-containing monomers can be used arbitrarily in the monomer components used in the manufacture of the (meth)acrylic acid polymers of the present invention, or they can be omitted.

[0261] Monomers having cyclic ether groups can be used without particular restriction, and can be monomers having polymerizable functional groups such as (meth)acryloyl or vinyl groups with unsaturated double bonds, and cyclic ether groups such as epoxy or oxetyl groups. Examples of epoxy-containing monomers include glycidyl (meth)acrylate, 3,4-epoxycyclohexyl methyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate glycidyl ether. Examples of oxetyl monomers include 3-oxetyl methyl (meth)acrylate, 3-methyl-oxetyl methyl (meth)acrylate, 3-ethyl-oxetyl methyl (meth)acrylate, 3-butyl-oxetyl methyl (meth)acrylate, and 3-hexyl-oxetyl methyl (meth)acrylate. They can be used alone or in combination of two or more.

[0262] In this invention, relative to the total mass of the monofunctional monomer components forming the (meth)acrylic polymer, the carboxyl-containing monomer and the monomer having a cyclic ether group are preferably 30% by mass or less, more preferably 27% by mass or less, and even more preferably 25% by mass or less.

[0263] Other components that form the (meth)acrylic acid polymers of the present invention include, for example, CH2=C(R) 1 COOR 2 (R 1 R represents a hydrogen atom or a methyl group. 2 Alkyl methacrylates, representing substituted alkyl groups or cyclic cycloalkyl groups having 1 to 3 carbon atoms.

[0264] As this is formed by CH2=C(R) 1 COOR 2Examples of monomers that can be represented include phenoxyethyl methacrylate, benzyl methacrylate, cyclohexyl methacrylate, 3,3,5-trimethylcyclohexyl methacrylate, and isobornyl methacrylate. They can be used alone or in combination of two or more.

[0265] In this invention, relative to the total amount of monofunctional monomer components forming (meth)acrylic polymers, the above-mentioned CH2=C(R) 1 COOR 2 The content of (meth)acrylate indicated is preferably 50% by mass or less, more preferably 45% by mass or less, and even more preferably 40% by mass or less.

[0266] Other comonomers that can be used include vinyl acetate, vinyl propionate, styrene, α-methylstyrene; glycol-based acrylate monomers such as polyethylene glycol methacrylate, polypropylene glycol methacrylate, methoxyethylene glycol methacrylate, and polypropylene glycol methacrylate; acrylate monomers such as tetrahydrofurfuryl methacrylate, fluoromethacrylate, organosilicon methacrylate, and 2-methoxyethyl acrylate; amide-containing monomers, amino-containing monomers, imide-containing monomers, N-acryloylmorpholine, and vinyl ether monomers. Additionally, monomers with cyclic structures such as terpene methacrylate and dicyclopentyl methacrylate can be used as comonomers.

[0267] Furthermore, silane monomers containing silicon atoms can also be used. Examples of silane monomers include 3-acryloyloxypropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 4-vinylbutyltrimethoxysilane, 4-vinylbutyltriethoxysilane, 8-vinyloctyltrimethoxysilane, 8-vinyloctyltriethoxysilane, 10-methacryloyloxydecyltrimethoxysilane, 10-acryloyloxydecyltrimethoxysilane, 10-methacryloyloxydecyltriethoxysilane, and 10-acryloyloxydecyltriethoxysilane.

[0268] In addition to the monofunctional monomers exemplified above, in order to adjust the cohesion of the damping part 2, the monomer components forming the (meth)acrylic polymer of the present invention may contain polyfunctional monomers as needed.

[0269] A multifunctional monomer is a monomer having at least two (meth)acryloyl or vinyl groups with unsaturated double bonds that are polymerizable. Specific examples include esters of polyols and (meth)acrylic acid such as polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, 1,2-ethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,12-dodecanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, and tetramethylolmethane tri(meth)acrylate; allyl methacrylate, vinyl methacrylate, divinylbenzene, epoxy acrylate, polyester acrylate, urethane acrylate, butyl di(meth)acrylate, and hexyl di(meth)acrylate. Among them, trimethylolpropane tri(meth)acrylate, hexanediol di(meth)acrylate, and dipentaerythritol hexa(meth)acrylate are suitable. Multifunctional monomers can be used alone or in combination of two or more.

[0270] The amount of multifunctional monomer used varies depending on the molecular weight, number of functional groups, etc., but is preferably 3 parts by mass or less, more preferably 2 parts by mass or less, and even more preferably 1 part by mass or less, relative to 100 parts by mass of monofunctional monomers. Furthermore, the amount of multifunctional monomer used is preferably more than 0 parts by mass, more preferably 0.001 parts by mass or more. By using the amount of multifunctional monomer within the above range, adhesive strength can be improved.

[0271] The shock-absorbing part 2 may contain a portion of the polymer of the aforementioned monomer components.

[0272] The UV absorber included in the UV-curable acrylic adhesive composition is not particularly limited, and examples include triazine-based UV absorbers, benzotriazole-based UV absorbers, benzophenone-based UV absorbers, oxybenzophenone-based UV absorbers, salicylate-based UV absorbers, and cyanoacrylate-based UV absorbers. These can be used alone or in combination of two or more. Triazine-based and benzotriazole-based UV absorbers are preferred among these. Furthermore, UV absorbers selected from at least one of triazine-based UV absorbers having two or fewer hydroxyl groups per molecule and benzotriazole-based UV absorbers having one benzotriazole backbone per molecule are preferred because they exhibit good solubility in the monomers used to form the UV-curable acrylic adhesive composition and have high UV absorption capacity around 380 nm.

[0273] The ultraviolet absorber can be used alone or in combination of two or more. The content of the ultraviolet absorber is preferably 0.1 to 5 parts by mass, more preferably 0.5 to 3 parts by mass, relative to 100 parts by mass of the monofunctional monomer component forming the (meth)acrylic polymer. By adding the ultraviolet absorber within the above range, the ultraviolet absorption function of the damping section 2 can be fully utilized without hindering ultraviolet polymerization, and therefore this is preferred.

[0274] The UV-curable acrylic adhesive composition used in this invention preferably contains a photopolymerization initiator (A) with an absorption band at a wavelength of 400 nm or higher. When the adhesive composition contains a UV absorber, if UV polymerization is carried out, the UV light is absorbed by the UV absorber and polymerization cannot be sufficient. However, the UV-curable acrylic adhesive composition used in this invention has a photopolymerization initiator with an absorption band at a wavelength of 400 nm or higher, so it can polymerize sufficiently even if a UV absorber is included.

[0275] Specific examples of photopolymerization initiators with absorption bands above 400 nm include bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (commercially available products such as Omnirad 819, manufactured by IGM Resins B.V.) and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (commercially available products such as Omnirad TPO H, manufactured by IGM Resins B.V.).

[0276] Photopolymerization initiators (A) with absorption bands above 400 nm can be used alone or in combination of two or more.

[0277] Furthermore, the amount of photopolymerization initiator (A) with an absorption band at wavelengths above 400 nm is not particularly limited, but it is preferably less than the amount of the aforementioned ultraviolet absorber. Relative to 100 parts by mass of the monofunctional monomer component forming the (meth)acrylic acid polymer, it is preferably about 0.005 to 1 part by mass, more preferably about 0.02 to 0.5 parts by mass. With the amount of photopolymerization initiator (A) within the above range, ultraviolet polymerization can be sufficiently carried out, and therefore this is preferable.

[0278] Furthermore, the aforementioned UV-curable acrylic adhesive composition may contain a photopolymerization initiator (B) having an absorption band at a wavelength less than 400 nm. Preferably, this photopolymerization initiator (B) does not have an absorption band at wavelengths above 400 nm. There are no particular limitations on the photopolymerization initiator (B), as long as it generates free radicals and initiates photopolymerization via ultraviolet light and has an absorption band at a wavelength less than 400 nm; any commonly used photopolymerization initiator can be used. For example, benzoin ether-based photopolymerization initiators, acetophenone-based photopolymerization initiators, α-ketool-based photopolymerization initiators, photoactive oxime-based photopolymerization initiators, benzoin-based photopolymerization initiators, benzyl-based photopolymerization initiators, benzophenone-based photopolymerization initiators, ketal-based photopolymerization initiators, thioxanone-based photopolymerization initiators, and acylphosphine oxide-based photopolymerization initiators can be used.

[0279] Photopolymerization initiator (B) with an absorption band at wavelengths less than 400 nm can be used alone or in combination of two or more. Photopolymerization initiator (B) with an absorption band at wavelengths less than 400 nm can be added without impairing the effects of the present invention; however, the amount added is preferably 0.005 to 0.5 parts by mass, more preferably 0.02 to 0.1 parts by mass, relative to 100 parts by mass of the monofunctional monomer component forming the (meth)acrylic polymer.

[0280] In this invention, it is preferable to first add a photopolymerization initiator (B) with an absorption band at a wavelength less than 400 nm to the aforementioned monomer component, irradiate with ultraviolet light, and then add the aforementioned photopolymerization initiator (A) with an absorption band at a wavelength greater than 400 nm and an ultraviolet absorber to a portion of the polymer (prepolymer composition) of the monomer component that is partially polymerized under ultraviolet light to carry out ultraviolet polymerization. When adding the photopolymerization initiator (A) with an absorption band at a wavelength greater than 400 nm to a portion of the polymer (prepolymer composition) of the monomer component that is partially polymerized under ultraviolet light irradiation, it is preferable to dissolve the photopolymerization initiator (A) in the monomer before adding it.

[0281] Furthermore, the UV-curable acrylic adhesive composition used in this invention may contain a silane coupling agent. The amount of silane coupling agent used is preferably 1 part by mass or less, more preferably 0.01 to 1 part by mass, and even more preferably 0.02 to 0.6 parts by mass, relative to 100 parts by mass of the monofunctional monomer component forming the (meth)acrylic polymer.

[0282] Specific examples of silane coupling agents include epoxy-containing silane coupling agents such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; amino-containing silane coupling agents such as 3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldiethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylene)propylamine, and N-phenyl-γ-aminopropyltrimethoxysilane; silane coupling agents containing (meth)acryloyl groups such as 3-acryloyloxypropyltrimethoxysilane and 3-methacryloyloxypropyltriethoxysilane; and silane coupling agents containing isocyanate groups such as 3-isocyanate propyltriethoxysilane.

[0283] The UV-curable acrylic adhesive composition used in this invention may contain a crosslinking agent. Specific examples of crosslinking agents include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, and silicone-based crosslinking agents. Crosslinking agents include zoline-based crosslinking agents, aziridine-based crosslinking agents, silane-based crosslinking agents, alkyl etherified melamine-based crosslinking agents, metal chelate-based crosslinking agents, and peroxide-based crosslinking agents. These crosslinking agents can be used alone or in combination of two or more. Isocyanate-based crosslinking agents are preferred among them.

[0284] The content of the crosslinking agent is preferably 5 parts by mass or less, more preferably 0.01 to 5 parts by mass, further preferably 0.01 to 4 parts by mass, and particularly preferably 0.02 to 3 parts by mass, relative to 100 parts by mass of the monofunctional monomer component that forms the (meth)acrylic polymer.

[0285] Isocyanate-based crosslinking agents refer to compounds that have two or more isocyanate groups in one molecule (including isocyanate regenerated functional groups that are temporarily protected by end-capping agents or polymerization). Examples of isocyanate-based crosslinking agents include aromatic isocyanates such as toluene diisocyanate and xylene diisocyanate, alicyclic isocyanates such as isophorone diisocyanate, and aliphatic isocyanates such as hexamethylene diisocyanate.

[0286] In addition to the components described above, the UV-curable acrylic adhesive composition used in this invention may appropriately include other additives depending on the application. Examples of such additives include tackifiers (e.g., tackifiers that are solid, semi-solid, or liquid at room temperature, composed of rosin derivative resins, polyterpene resins, petroleum resins, oil-soluble phenolic resins, etc.); fillers such as hollow glass spheres; plasticizers; anti-aging agents; antioxidants, etc.

[0287] In this invention, the viscosity of the UV-curable acrylic adhesive composition is preferably adjusted to be suitable for coating operations. The viscosity of the UV-curable acrylic adhesive composition can be adjusted, for example, by adding various polymers such as thickening additives or multifunctional monomers, to partially polymerize the monomer components in the UV-curable acrylic adhesive composition. It should be noted that this partial polymerization can be carried out before or after adding the various polymers such as thickening additives or multifunctional monomers. The viscosity of the aforementioned UV-curable acrylic adhesive composition varies depending on the amount of additives, etc. Therefore, the polymerization rate when partially polymerizing the monomer components in the UV-curable acrylic adhesive composition cannot be generalized, but as a reference value, it is preferably about 20% or less, more preferably about 3 to 20%, and even more preferably about 5 to 15%. If it exceeds 20%, the viscosity becomes too high, and coating may become difficult.

[0288] The damping portion 2 can be formed by coating the ultraviolet-curable acrylic adhesive composition described above onto the damping portion 1 and irradiating the ultraviolet-curable acrylic adhesive composition with ultraviolet light. Alternatively, the film-like damping portion 2 can be formed by coating the ultraviolet-curable acrylic adhesive composition described above onto a substrate and then irradiating the ultraviolet-curable acrylic adhesive composition with ultraviolet light.

[0289] There are no particular limitations on the substrate; for example, it can be suitable for various substrates such as release film and transparent resin film substrates.

[0290] Examples of suitable materials for release films include resin films such as polyethylene, polypropylene, polyethylene terephthalate, and polyester films; porous materials such as paper, cloth, and nonwoven fabrics; meshes; foamed sheets; metal foils; and their laminates. However, from the viewpoint of excellent surface smoothness, resin films are more suitable.

[0291] Examples of resin films include polyethylene films, polypropylene films, polybutene films, polybutadiene films, polymethylpentene films, polyvinyl chloride films, vinyl chloride copolymer films, polyethylene terephthalate films, polybutylene terephthalate films, polyurethane films, and ethylene-vinyl acetate copolymer films.

[0292] The thickness of the release film is typically 5–200 μm, preferably around 5–100 μm. The release film can also be subjected to release and anti-fouling treatments such as those using silicone-based, fluorine-based, long-chain alkyl-based, or fatty acid amide-based release agents, silica powder, etc., or antistatic treatments such as coating-type, kneading-type, and vapor-depositing-type treatments. In particular, by appropriately performing release treatments such as silicone treatment, long-chain alkyl treatment, or fluorine treatment on the surface of the release film, the peelability from the shock-absorbing part 2 can be further improved.

[0293] There are no particular limitations on the transparent resin film substrate; various transparent resin films can be used. This resin film substrate is formed from a single layer of film. Examples of materials include, for instance, polyester resins such as polyethylene terephthalate and polyethylene naphthalate, acetate resins, polyethersulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth)acrylic resins, polyvinyl chloride resins, polyvinylidene chloride resins, polystyrene resins, polyvinyl alcohol resins, polyarylate resins, and polyphenylene sulfide resins. Polyester resins, polyimide resins, and polyethersulfone resins are particularly preferred.

[0294] The thickness of the transparent resin film substrate is preferably 15–200 μm, more preferably 25–188 μm.

[0295] The method of applying the above-mentioned UV-curable acrylic adhesive composition can appropriately use conventionally known methods such as roller coating, licking coating, gravure coating, reverse roller coating, roller brushing, spraying, dip roller coating, bar coating, doctor blade coating, air knife coating, curtain coating, die lip coating, and die coating machine, without any particular limitation.

[0296] The irradiance of the UV light irradiating the UV-curable acrylic adhesive composition is preferably 5 mW / cm². 2 That's all. If the ultraviolet irradiance is less than 5 mW / cm². 2 Sometimes, this leads to a longer polymerization reaction time and lower productivity. It should be noted that the preferred UV irradiance is 200 mW / cm². 2 The following applies if the ultraviolet irradiance exceeds 200 mW / cm². 2 If this occurs, the photopolymerization initiator is consumed rapidly, sometimes leading to a decrease in polymer molecular weight, especially a reduction in holding power at high temperatures. Furthermore, the cumulative ultraviolet light intensity is preferably 100 mJ / cm². 2 ~5000mJ / cm 2 .

[0297] The ultraviolet lamp used in this invention is not particularly limited, but LED lamps are preferred. LED lamps emit less heat compared to other ultraviolet lamps, thus suppressing the temperature during polymerization of the damping section 2. Therefore, it is possible to prevent the polymer from becoming low in molecular weight, prevent a decrease in the cohesive strength of the damping section 2, and improve the holding power at high temperatures when forming the adhesive sheet. Furthermore, multiple ultraviolet lamps can be combined. Additionally, ultraviolet light can be irradiated intermittently, with a bright period of ultraviolet light irradiation and a dark period of no ultraviolet light irradiation.

[0298] In this invention, the final polymerization rate of the monomer components in the UV-curable acrylic adhesive composition is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more.

[0299] In this invention, the peak wavelength of the ultraviolet light irradiating the above-mentioned UV-curable acrylic adhesive composition is preferably in the range of 200-500 nm, more preferably in the range of 300-450 nm. If the peak wavelength of the ultraviolet light exceeds 500 nm, the photopolymerization initiator may not decompose and the polymerization reaction may not be initiated. Furthermore, if the peak wavelength of the ultraviolet light is less than 200 nm, the polymer chains may sometimes be cleaved, resulting in reduced adhesion.

[0300] The reaction is hindered by oxygen in the air; therefore, in order to isolate oxygen, it is preferable to form a release film on the coating layer of the UV-curable acrylic adhesive composition, or to carry out the photopolymerization reaction under a nitrogen atmosphere. Examples of release films include the aforementioned release films.

[0301] If the thinning of the optical laminate is also considered, the thickness of the damping part 2 is preferably 5 to 60 μm, more preferably 15 to 50 μm, and even more preferably 25 to 40 μm.

[0302] From the perspective of controlling tanδ, the weight-average molecular weight of the resin material used in the damping section 2 is preferably 100,000 to 5,000,000, more preferably 200,000 to 1,000,000.

[0303] From the viewpoint of impact resistance and bending performance in low-temperature environments, the glass transition temperature of the damping part 2 is preferably below 0°C, and more preferably below -20°C.

[0304] From the viewpoint of impact resistance and flexural strength, the stored elastic modulus of the damping section 2 is preferably 1.0 × 10⁻⁶. －6 ~1.0×10 －3 GPa, more preferably 1.0 × 10⁻⁶ GPa. －6 ~1.0×10 －4 GPa.

[0305] The tanδ (tanδ3) of the damping part 2 is not particularly limited as long as it satisfies the relationship of the above formula (1), but it is preferably 0.01 to 1.0, and more preferably 0.1 to 1.0.

[0306] In one embodiment of the present invention, the weight-average molecular weight of the resin material used in the damping section 1 is preferably greater than that of the resin material used in the damping section 2. This configuration allows for more effective application of the invention's properties.

[0307] [Thin-film glass]

[0308] Examples of materials that can be used as thin-film glass in this invention include lithium aluminosilicate glass, soda-lime glass, borosilicate glass, alkali metal aluminosilicate glass, and aluminosilicate glass with low alkali content.

[0309] The glass constituting the thin-film glass is preferably alkali-free glass that does not contain any alkali components. Specifically, it is preferably glass with an alkali content of 1000 ppm or less. The alkali content in the thin-film glass is preferably 500 ppm or less, more preferably 300 ppm or less. Thin-film glass containing a large amount of alkali components undergoes cation replacement on the surface, which easily leads to sodium and calcium blowing. As a result, the density of the glass surface layer is easily reduced, and sometimes the thin-film glass breaks.

[0310] Thin-film glass can be formed using commonly known methods, such as float glass, down-draw glass, and overflow down-draw glass. Among these methods, considering that the surface of the thin-film glass does not come into contact with the forming component during forming and that the surface of the resulting thin-film glass is less prone to damage, the overflow down-draw glass or float glass is preferred.

[0311] The thin-film glass used in this invention can also be obtained by grinding thick glass, such as borosilicate glass, to the desired thickness. However, it is difficult to obtain thin-film glass with a thickness of less than 200 μm by grinding and polishing thick glass sheets. Therefore, the float glass process is preferred for obtaining the thin-film glass of this invention.

[0312] The thinner the glass, the more difficult it is to process and manufacture extremely thin glass sheets, resulting in lower glass strength and a higher probability of breakage. To facilitate the processing and manufacturing of thin-film glass, a method has been proposed that involves temporarily bonding the thin-film glass to a thicker support substrate (hereinafter also referred to as "carrier substrate") while processing, and then peeling off the support substrate as a subsequent processing step to obtain the thin-film glass.

[0313] For example, according to International Publication No. 2017 / 066924, soda-lime glass with a thickness of less than 100 μm can be manufactured through the following process. Its characteristic is that it includes the following process.

[0314] (Step 1) A process of forming a thin film glass on a glass carrier substrate having a bonding surface in a manner that contacts a first surface of the thin film glass, and attaching a contact film (also called a "contact film") with adhesive force to a second surface opposite to the first surface.

[0315] That is, such as Figure 1 As shown in step 1, the above-mentioned method for manufacturing thin film glass includes the following steps: feeding a material for forming thin film glass of a desired thickness into a carrier substrate 21 having sufficient strength and easy-to-process thickness, forming a first surface of thin film glass 22 that contacts the carrier substrate 21, and then attaching a contact film 23 to a second surface opposite to the first surface.

[0316] (Step 2) Next, the thin-film glass 22 is peeled off from the carrier substrate 21 using a contact film 23 with high adhesive strength. Figure 1 (Process 2)

[0317] (Step 3) The process of removing the contact film 23 from the second surface of the thin film glass 22 peeled off from the carrier substrate by weakening the adhesive strength of the contact film (electromagnetic radiation irradiation 24). Figure 1 (Process 3)

[0318] That is, by using the contact film 23 for maintaining the safety of the thin film glass 22, the thin film glass 22 can have a protective function, thereby protecting, for example, the exposed surface of the thin film glass 22 from possible mechanical damage, and can be handled safely and easily.

[0319] The contact membrane can contain rigid or flexible materials, and polyolefins (PO) such as polyethylene terephthalate (PET) or polyethylene (PE) are preferred materials.

[0320] Contact films are typically bonded to thin-film glass via an adhesive layer consisting of an adhesive applied to one side of a substrate. Alternatively, contact films can be directly bonded to thin-film glass using the inherent adhesive properties of the film itself.

[0321] The adhesive force between the contact film and the second surface of the thin film glass is selected such that sufficient force is transmitted to the thin film glass during peeling using a peeling device in order to eliminate the bonding force between the carrier substrate and the thin film glass during pressing.

[0322] The contact film can be provided in the form of foil or tape, which can be, for example, rolled from a roller, or it can be provided in the form of sheet. Preferably, the thickness of the contact film is 50 μm or more, more preferably 80 μm or more, even more preferably 125 μm or more, and particularly preferably 150 μm or more.

[0323] Thin-film glass is preferably manufactured by the aforementioned down-drawing method, overflow down-drawing method, or float glass method.

[0324] The carrier substrate preferably has a thickness of at least 100 μm, more preferably 300 μm, and even more preferably 500 μm, and a maximum size of at least 3 inches (1 inch is 2.54 cm), more preferably 6 inches, even more preferably 8 inches, and particularly preferably 12 inches. Specifically, the carrier substrate may have a size greater than that of a first-generation glass substrate, such as a second- to eighth-generation size, or an even larger size, such as 1×1m to 3×3m. The carrier substrate may have various shapes, such as rectangular, elliptical, or circular.

[0325] The thin-film glass, together with the contact film, is peeled off from the carrier substrate using the adhesive force of the contact film. Then, the contact film is peeled off to obtain the thin-film glass monomer.

[0326] In a preferred embodiment, the contact film is preferably subjected to an adhesive weakening treatment before being removed from the thin-film glass, thereby reducing the adhesive strength. The weakening treatment is preferably selected to reduce the adhesive strength to below 0.5 N / 25 mm.

[0327] Fragility treatment can be achieved by appropriately selecting electromagnetic radiation such as infrared, ultraviolet, or visible light. The choice of electromagnetic radiation depends on the adhesive material used; it can be narrow-band, cover a wider frequency band, or even laser radiation.

[0328] Preferably, electromagnetic radiation with wavelengths on the outer edge of the visible spectrum is selected so that the adhesive strength does not deteriorate upon exposure to visible light. Various commercially available adhesive materials are available that can be at least partially deactivated by irradiation with this electromagnetic radiation, and these can be appropriately selected as contact films.

[0329] In addition, heat treatment can be used as a weakening treatment if the adhesion of the contact film can be reduced by raising or lowering the temperature.

[0330] Electromagnetic radiation irradiation is preferably carried out from the outside of the contact film, that is, the side of the thin-film glass that is not bonded.

[0331] Preferred contact films include, for example, the contact film sold by Daoming Optical Co., Ltd. under the trade name "NDS4150-20", and the corresponding fragility treatment includes ultraviolet irradiation with a wavelength of 365nm.

[0332] The specific manufacturing method of the thin-film glass is described in the examples. Furthermore, commercially available products such as those manufactured by SCHOTT Corporation or Nippon Electric Glass Co., Ltd. can be used as the thin-film glass.

[0333] The thickness of the thin-film glass is 10–40 μm. When the thickness of the thin-film glass is less than 10 μm, the impact resistance of the optical laminate decreases. On the other hand, when the thickness of the thin-film glass exceeds 40 μm, the flexibility of the optical laminate decreases. In addition, the thinning of the optical laminate becomes difficult. The thickness of the thin-film glass is preferably 15–40 μm, more preferably 15–30 μm.

[0334] According to one embodiment of the present invention, when the thickness of the thin film glass is set as A (unit: μm) and the total thickness of the restraining part, the damping part 1, and the damping part 2 is set as B (unit: μm), it is preferable to satisfy the relationship of the following formula (3). If it is within this range, the effects of the present invention can be more effectively exerted.

[0335] 1≤B / A≤8 (3)

[0336] It should be noted that an adhesive portion may be further provided on the side of the thin-film glass opposite to the side with the damping portion 2. The material used in this adhesive portion can be the same as the material described in the damping portion 2. This adhesive portion can be a single layer or two or more layers. However, when the adhesive portion, such as thin-film glass / adhesive portion 3 / adhesive portion 4, is a double-layer structure, the storage elastic modulus of adhesive portion 3 is preferably higher than that of adhesive portion 4.

[0337] [Manufacturing Method]

[0338] The manufacturing method of the optical laminate of the present invention is not particularly limited, and a method in which the restraint part, the damping part 1, the damping part 2 and the thin film glass are arranged in sequence can be cited as an example. Each part may have an adhesive part as described above, or the parts may be bonded together using a UV adhesive or the like.

[0339] [Display device]

[0340] The optical laminate of the present invention is applicable to a display device having a light-emitting device. That is, according to another embodiment of the present invention, a display device having a light-emitting device and the optical laminate of the present invention is provided. Furthermore, according to a preferred embodiment of the present invention, a display device having a light-emitting device and the optical laminate of the present invention, wherein the constraint portion of the optical laminate is disposed closest to the recognition side is provided.

[0341] There are no particular limitations on what can be used as a light-emitting device; examples include plasma display devices and electroluminescent devices.

[0342] While embodiments of the invention have been described in detail, it is clear that this is illustrative and exemplary, not restrictive, and the scope of the invention should be interpreted as the scope of the appended patent claims.

[0343] This invention includes the following aspects and forms:

[0344] 1. An optical laminate, comprising, in sequence, a constraint portion, a damping portion 1, a damping portion 2, and a thin film glass with a thickness in the range of 10–40 μm, wherein,

[0345] When the tanδ of the constraint part is set as tanδ1, the tanδ of the damping part 1 is set as tanδ2, and the tanδ of the damping part 2 is set as tanδ3, the tanδ1, tanδ2 and tanδ3 satisfy the following relationship (1).

[0346] tanδ1<tanδ2<tanδ3 (1)

[0347] 2. According to the optical laminate described in 1. above, when the storage elastic modulus of the constraint portion is set as elastic modulus 1 (unit: GPa) and the storage elastic modulus of the damping portion 1 is set as elastic modulus 2 (unit: GPa), the elastic modulus 1 and the elastic modulus 2 satisfy the following relationship (2):

[0348] Elastic modulus 1 / elastic modulus 2 > 8 (2).

[0349] 3. The optical laminate according to 1. or 2. above, wherein the constraint portion and the damping portion 1 are films.

[0350] 4. The optical laminate according to any one of 1. to 3. above, wherein,

[0351] Let the thickness of the above-mentioned thin-film glass be A (unit: μm).

[0352] When the total thickness of the aforementioned restraint part, the aforementioned damping part 1, and the aforementioned damping part 2 is set as B (unit: μm),

[0353] The following relationship (3) must be satisfied:

[0354] 1≤B / A≤8 (3).

[0355] 5. The optical laminate according to any one of 1. to 4. above, wherein the damping portion 1 is a film comprising at least a thermoplastic (meth)acrylic resin and a graft copolymer.

[0356] 6. The optical laminate according to 5. above, wherein the content of the graft copolymer relative to the total mass of the film is 60 to 90% by mass.

[0357] 7. A display device having a light-emitting device and an optical laminate as described in any one of 1. to 6., wherein the constraint portion of the optical laminate is disposed closest to the recognition side.

[0358] Example

[0359] The effects of the present invention are illustrated by the following examples. However, the technical scope of the present invention is not limited to the following examples. In the following examples, the terms "%" and "parts" are used, but unless otherwise specified, they represent "mass %" and "parts by mass".

[0360] (Glass transition temperature)

[0361] The glass transition temperature (Tg) of each component constituting the optical laminate was determined using DSC (Differential Scanning Calorimetry) according to JIS K 7121 (2012).

[0362] (weight-average molecular weight)

[0363] The weight-average molecular weight (Mw) of the polymers constituting the optical laminate was determined using gel permeation chromatography (Tosoh Corporation, HLC8220GPC) and columns (Tosoh Corporation, TSK-GELG6000, HXL-G5000, HXL-G5000, HXL-G4000, HXL-G3000HXL tandem). 20 mg ± 0.5 mg of the sample was dissolved in 10 mL of tetrahydrofuran and filtered through a 0.45 mm filter. 100 mL of this solution was injected into the column (temperature 40 °C), and the value was determined at the detector RI temperature of 40 °C, followed by styrene conversion.

[0364] (tanδ, storage elastic modulus)

[0365] The stored elastic modulus and tanδ of the restraint part and the damping part 1 were measured using a dynamic viscoelasticity measuring device (model: RSA-3) manufactured by TA Instruments Japan Co., Ltd., under the following test conditions at 25°C:

[0366] • Test conditions (dynamic viscoelasticity test)

[0367] Testing machine: Dynamic viscoelasticity measuring device (model: RSA-3) manufactured by TAInstruments Japan Co., Ltd.

[0368] Deformation method: stretching

[0369] Preload: 55g

[0370] Temperature range: -70 to 200℃

[0371] Frequency: 1.0Hz

[0372] Displacement: ±0.1%

[0373] Sample: 5mm wide

[0374] Chuck pitch: 20mm.

[0375] In addition, the stored elastic modulus and tanδ of the damping section 2 were measured at 25°C using a nanoindentation device (model: G200XP) manufactured by Keysight Technologies under the following test conditions:

[0376] • Test conditions (dynamic viscoelasticity test)

[0377] Testing equipment: Keysight Technologies nanoindentation device (model: G200XP)

[0378] Deformation method: Press-fit

[0379] Temperature range: -100℃ to 100℃

[0380] Frequency: 1Hz

[0381] Displacement: 100nm

[0382] Sample size (shape, etc.): 10×10mm, thickness approximately 1mm.

[0383] (Example 1)

[0384] [Form of the constraint section]

[0385] (Preparation of coatings)

[0386] Place the following materials into a sealed container, heat, and stir until completely dissolved to prepare a coating:

[0387] (Coating composition)

[0388]

[0389]

[0390] Next, a cellulose triacetate film is manufactured using a solution casting film-forming apparatus. Specifically, a ring-shaped surface with an average three-dimensional surface roughness (Ra) of 1.0 nm is formed using a SUS316 milling machine as a support for casting the above-mentioned coating.

[0391] Using a casting die 3 composed of a coat hanger die head, the coating filtered as described above is uniformly cast onto an annular belt support made of SUS316 at a temperature of 35°C.

[0392] In this way, the web formed on the support is conveyed on the support and dried with a drying air at a constant temperature of 30°C. It is then peeled off from the support using a peeling roller. Then, it is stretched 1.06 times in the width direction using a tenter frame with a residual solvent content of 10% in an atmosphere at 100°C. The width holding is then released, and the web is dried using a drying device at 125°C while being conveyed by rollers. Finally, it is wound using a winding device.

[0393] The obtained triacetate cellulose membrane (TAC membrane) has a thickness of 30 μm, a width of 2000 mm, and a winding length of 3000 m.

[0394] [Formation of damping section 1]

[0395] <Thermoplastic (meth)acrylic resins>

[0396] As a thermoplastic (meth)acrylic resin, an MMA (methyl methacrylate) / PMI (phenylmaleimide) / MA (methyl acrylate) copolymer (85 / 10 / 5 mass ratio, Mw: 2 million, Tg: 122℃) was prepared.

[0397] <Graft copolymer (rubber particles)>

[0398] The graft copolymer was prepared by the following method.

[0399] The following substances were added to an 8L polymerization unit equipped with a mixer:

[0400]

[0401] After fully purging the polymerization apparatus with nitrogen to a temperature of 80°C, 0.021 parts by mass of potassium persulfate were added as a 2% by mass aqueous solution. Next, 0.07 parts by mass of polyoxyethylene lauryl ether phosphoric acid was added to 21 parts by mass of a monomer mixture (c') consisting of 84.6% by mass of methyl methacrylate, 5.9% by mass of n-butyl acrylate, 7.9% by mass of styrene, 0.5% by mass of allyl methacrylate, and 1.1% by mass of n-octyl mercaptan to obtain a mixture. This mixture was continuously added to the above solution over 63 minutes. Furthermore, by continuing the polymerization reaction for 60 minutes, the innermost rigid polymer (crosslinked polymer (c)) was obtained.

[0402] Then, 0.021 parts by mass of sodium hydroxide and 0.062 parts by mass of potassium persulfate were added in the form of a 2% by mass aqueous solution. Next, 0.25 parts by mass of polyoxyethylene lauryl ether phosphoric acid were added to 39 parts by mass of a monomer mixture (a') consisting of 80.0% by mass of n-butyl acrylate, 18.5% by mass of styrene, and 1.5% by mass of allyl methacrylate to obtain a mixture, which was continuously added over 117 minutes. After the addition was completed, 0.012 parts by mass of potassium persulfate were added in the form of a 2% by mass aqueous solution, and the polymerization reaction was continued for 120 minutes to obtain a soft layer (a layer composed of an acrylic rubber polymer (a)). Using the glass transition temperatures of the homopolymers of each monomer constituting the acrylic rubber polymer (a), the glass transition temperature (Tg) of the soft layer, calculated based on the average composition ratio, was -30°C.

[0403] Then, 0.04 parts by mass of potassium persulfate were added in the form of a 2% by mass aqueous solution, and 26.1 parts by mass of a monomer mixture (b') consisting of 97.5% by mass of methyl methacrylate and 2.5% by mass of n-butyl acrylate was added continuously over 78 minutes. The polymerization reaction was then continued for 30 minutes to obtain the methacrylic polymer (b).

[0404] The obtained methacrylic polymer (b) was added to a 3% (w / w) sodium sulfate warm aqueous solution for salting out and coagulation. Then, after repeated dehydration and washing, it was dried to obtain three-layer acrylic graft copolymer particles (rubber particles). The average particle size of the obtained rubber particles was measured using a Zeta potential particle size analyzer (Otsuka Electronics Co., Ltd. ELSZ-2000ZS), and the result was 200 nm.

[0405] <Preparation of Surfactant Solutions>

[0406] A surfactant solution was prepared by dissolving 2 parts by mass of Phosphhanol ML-220 (polyoxyethylene lauryl ether phosphoric acid, manufactured by Toho Chemical Industry Co., Ltd.) in 98 parts by mass of methyl ethyl ketone (MEK).

[0407] <Paint Making>

[0408] 85.3 parts by mass of methyl ethyl ketone, used as a solvent, were added to a dissolving tank where the nitrogen concentration was controlled at 98.5% by volume and the oxygen concentration at 1.5% by volume. Next, 15 parts by mass of the surfactant solution prepared above were added to the dissolving tank containing this solvent, and the mixture was stirred for 30 minutes. Then, 8.8 parts by mass of the acrylic graft copolymer particles obtained above were added while stirring, and the mixture was stirred at 23°C for 1 hour to disperse the graft copolymer. Finally, 2.2 parts by mass of thermoplastic (meth)acrylic resin were added to the dissolving tank while stirring, and the mixture was stirred at 23°C for 4 hours to completely dissolve the solid components, thus completing the coating.

[0409] As a substrate, a PET film (manufactured by Toyobo Co., Ltd., TN100, 50 μm thick, with a release layer containing a non-silicone release agent) was prepared. A coating was applied to the release layer of this PET film using a mold via a back-coating method, and then dried at 80°C in an atmosphere with a solvent concentration of 0.18% by volume, to obtain a 20 μm thick film that forms the shock-absorbing part 1.

[0410] The obtained film-like damping part 1 was bonded to the prepared constraint part using a UV adhesive (manufactured by Toa Synthetic Co., Ltd., model: Aronix (registered trademark) UV-3610), and then the substrate was peeled off. The glass transition temperature (Tg) of the damping part 1 obtained in this way is 10°C.

[0411] [Formation of shock absorber 2]

[0412] (Preparation of UV-curable acrylic adhesive composition (a-1))

[0413] In a monomer mixture consisting of 78 parts by mass of 2-ethylhexyl acrylate (2EHA), 18 parts by mass of N-vinyl-2-pyrrolidone (NVP), and 4 parts by mass of 2-hydroxyethyl acrylate (HEA), 0.035 parts by mass of 1-hydroxycyclohexylphenyl ketone (trade name: Omnirad 184, with an absorption band at wavelengths of 200–370 nm, manufactured by IGMresins BV) and 0.035 parts by mass of 2,2-dimethoxy-1,2-diphenylethane-1-one (trade name: Omnirad 651, with an absorption band at wavelengths of 200–380 nm, manufactured by IGMresins BV) were added as photopolymerization initiators. The mixture was then irradiated with ultraviolet light until the viscosity (measurement conditions: BH viscometer No. 5 rotor, 10 rpm, measurement temperature 30 °C) reached approximately 20 Pa·s, yielding a prepolymer composition (polymerization rate: 8%) of a portion of the above monomer components polymerized. Next, 0.15 parts by weight of hexanediol diacrylate (HDDA) and 0.3 parts by weight of silane coupling agent (trade name: KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) were added to the prepolymer composition and mixed to obtain an acrylic adhesive composition.

[0414] In the obtained acrylic adhesive composition, 1.4 parts by weight of 2,4-bis-[{4-(4-ethylhexyloxy)-4-hydroxy}-phenyl]-6-(4-methoxyphenyl)-1,3,5-triazine (trade name: Tinosorb (registered trademark) S, manufactured by BASF JAPAN Co., Ltd.) and 0.2 parts by weight of bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (trade name: Omnirad (registered trademark) 819, which has an absorption band at wavelengths of 200-450 nm, manufactured by IGM Resins BV Co., Ltd.) were added and stirred to obtain a UV-curable acrylic adhesive composition (a-1).

[0415] The obtained UV-curable acrylic adhesive composition (a-1) was applied to the surface of the shock-absorbing part 1 opposite to the surface where the restraint part was formed, with a cured thickness of 25 μm. A release film was then further adhered to this surface. Then, under an illuminance of 6.5 mW / cm², [the process was repeated]. 2 Cumulative light intensity: 1500 mJ / cm 2 The composition is cured by ultraviolet irradiation under certain conditions to form the shock-absorbing part 2 (labeled as adhesive 1 in Table 1 below). The release film is peeled off, thereby obtaining a laminate a having a restraining part, shock-absorbing part 1, and shock-absorbing part 2 in sequence. The Tg of the shock-absorbing part 2 is -20°C. It should be noted that the type of shock-absorbing part 2 produced by this method is described as "adhesive 1" in Table 1 below.

[0416] [Production of thin-film glass]

[0417] Fabricate 12-inch thin-film glass (soda-lime glass) according to the following process:

[0418] (Step 1) A thin film glass is formed on a carrier substrate having a bonding surface in such a way that the first surface of the thin film glass is in contact with the surface, and a contact film (also called a "contact film") with adhesive force is attached to a second surface opposite to the first surface of the thin film glass.

[0419] (Step 2) Next, the thin-film glass is peeled off from the carrier substrate using a contact film with high adhesion.

[0420] (Step 3) A process of removing the contact film from the second surface of the thin film glass peeled off from the carrier substrate by a fragility treatment (electromagnetic radiation irradiation) that weakens the adhesive strength of the contact film.

[0421] In step 1, a thin-film glass is formed to a specified thickness in contact with a carrier substrate with a thickness of 500 μm, and then the contact film described below is attached. Next, the thin-film glass and the contact film are peeled off from the carrier substrate together in 30 seconds, and the carrier substrate is removed (step 2). The contact film is a 150 μm thick film containing polyolefin (PO), and further has an adhesive layer with a thickness of 10 μm. A commercially available contact film under the trade name "NDS4150-20" is used.

[0422] Next, the exposed contact film is subjected to a weakening treatment to reduce adhesive strength. This weakening treatment is performed by irradiating the contact film with 365nm ultraviolet light for 10 seconds. The ultraviolet irradiance is 500mW / cm². 2 The cumulative light intensity is 500 mJ / cm². 2 At this point, the adhesive strength before the fragility treatment was 11 N / 25 mm, but after the fragility treatment, the adhesive strength decreased to 0.4 N / 25 mm. Therefore, the contact film can be easily peeled off from the thin-film glass to obtain a thin-film glass with a thickness of 30 μm (step 3).

[0423] [Fabrication of Optical Laminates]

[0424] The thin film glass obtained above and the damping part 2 of the laminate 1 obtained above are bonded together to obtain an optical laminate 1a having a restraining part, a damping part 1, a damping part 2 and a thin film glass in sequence. An adhesive part 1 with a thickness of 25 μm is formed on the thin film glass in the same way as described in the above [formation of damping part 2], and a release film (manufactured by Toyobo Co., Ltd., model: TN100, thickness: 50 μm) is attached to the adhesive part 1 to complete the optical laminate 1A.

[0425] (Example 2)

[0426] Instead of UV adhesive, an adhesive portion 2 is provided between the restraint portion and the shock-absorbing portion 1 by the method described below. Otherwise, an optical laminate 2A is obtained in the same manner as in Example 1.

[0427] [Adhesive Part 2]

[0428] 99 parts by mass of butyl acrylate, 1 part by mass of acrylic acid, and 0.03 parts by mass of 2,2'-azobisisobutyronitrile (2,2'-azobisisobutyronitrile) as a polymerization initiator were added to 200 parts by mass of ethyl acetate and stirred under reflux for 5 hours to obtain a solution containing an acrylate copolymer with a weight average molecular weight of 1.8 million.

[0429] Relative to 100 parts by mass of the solid content of the acrylate copolymer solution obtained above, 15 parts by mass of trimethylolpropane triacrylate (a multifunctional active energy ray curable compound), 1 part by mass of a 1:1 mixture of benzophenone and 1-hydroxycyclohexylphenyl ketone (Omnirad 500, manufactured by IGMresins BV) as a photopolymerization initiator, 1 part by mass of trimethylolpropane-modified toluene diisocyanate (L-45, manufactured by Soken Chemical Co., Ltd.) as a crosslinking agent, and 1 part by mass of γ-glycidoxypropyltrimethoxysilane (KBM-403, manufactured by Shin-Etsu Chemical Co., Ltd.) as a silane coupling agent were added, and the solution was further diluted with methyl ethyl ketone to obtain a coating solution with a solid content of 15% by mass.

[0430] The coating liquid is applied to the constraint part using a doctor blade coater and dried at 90°C for 1 minute, thereby forming the adhesive part 2 before light curing.

[0431] The adhesive part 2 is bonded to the shock-absorbing part 1 without being irradiated with ultraviolet light. Within one hour after bonding, an electrodeless lamp (manufactured by Fusion Corporation) is used from the side of the shock-absorbing part 1 with an illuminance of 600mW / cm². 2 Cumulative light intensity 150 mJ / cm 2 Irradiate with ultraviolet light at a wavelength of 365 nm. This forms an adhesive portion 2 with a thickness of 25 μm.

[0432] (Example 3)

[0433] A 10 μm thick TAC film was fabricated using the same method as described above for the formation of the constraint portion, and this film was used as the constraint portion. Furthermore, the thickness of the damping portion 1 was changed to 17 μm, the thickness of the damping portion 2 was changed to 10 μm, and the thickness of the thin-film glass was changed to 15 μm. Otherwise, the optical laminate 3A was fabricated in the same manner as in Example 1.

[0434] (Example 4)

[0435] As the shock-absorbing part 1, a COP film prepared by the following method is used. Otherwise, an optical laminate 4A is prepared in the same manner as in Example 1.

[0436] [COP film fabrication]

[0437] (Preparation of particulate dispersions and additive solutions)

[0438] 11.3 parts by weight of microparticles (AEROSIL (registered trademark) R972V, manufactured by AEROSIL Co., Ltd. of Japan) and 84 parts by weight of ethanol were mixed in a dissolver for 50 minutes and then dispersed with Manton Gaulin.

[0439] Five parts by mass of the particulate dispersion were slowly added to 100 parts by mass of dichloromethane, which was thoroughly stirred in a dissolving tank. The dispersion was then carried out using a mill to ensure that the secondary particle size was within a specified range. The mixture was then filtered through a FINEMET NF filter manufactured by Nippon Seiki Co., Ltd., to prepare the particulate additive solution.

[0440] (Preparation of coatings)

[0441] Prepare a coating with the following composition. First, add dichloromethane and ethanol to a pressurized dissolving vessel. Then, while stirring, add a cyclic olefin resin, an additive (a compound of chemical formula (A) below), and a particulate additive solution to the same vessel. Heat the mixture and dissolve it completely while stirring. Filter the solution using Anji Filter Paper Co., Ltd. No. 244 to prepare the coating.

[0442] (Composition of paint)

[0443]

[0444]

[0445] Next, using a circular tape casting device, the coating is evenly cast onto a stainless steel tape support at a temperature of 31°C and a width of 1800mm. The temperature of the stainless steel tape is controlled at 28°C. The conveying speed of the stainless steel tape is 20m / min.

[0446] The solvent was evaporated on a stainless steel strip support until the residual solvent in the cast film became 30% by mass. Then, the film was peeled from the stainless steel strip support at a peel tension of 128 N / m. The peeled film was stretched 1.1 times its original length in the width direction at 160°C. The residual solvent at the start of stretching was 5% by mass. Drying was then completed while the drying area was conveyed by multiple rollers. The ends held by the tenter frame were cut using a laser cutter, and then the film was wound to obtain a COP film with a thickness of 20 μm. The glass transition temperature of the obtained COP film was 160°C.

[0447] (Example 5)

[0448] A 15 μm thick TAC film is fabricated using the same method as described above for the formation of the constraint portion, and this film is used as the constraint portion. The thickness of the damping portion 2 is set to 10 μm. Otherwise, the optical laminate 5A is fabricated in the same manner as in Example 1.

[0449] (Example 6)

[0450] A 50 μm thick TAC film is fabricated using the same method as described above for the formation of the constraint portion. This film is used as the constraint portion. The thicknesses of the damping portion 1 and the damping portion 2 are set to 50 μm. Otherwise, the optical laminate 6A is fabricated in the same manner as in Example 1.

[0451] (Example 7)

[0452] As the shock-absorbing part 1, a polyurethane resin film formed by the following method is used, and the optical laminate 7A is made in the same manner as in Example 1.

[0453] <Synthesis of isocyanurate derivatives from hexamethylene diisocyanate (hereinafter referred to as NCO-TR)>

[0454] In a 1000 mL four-necked flask equipped with a stirrer, thermometer, and cooling tube, 1000 parts by weight of hexamethylene diisocyanate (manufactured by Tosoh Corporation, NCO content: 49.9%, hereinafter referred to as HDI), 1.0 part by weight of phenol, and 16 parts by weight of 1,3-butanediol (manufactured by DAICL Corporation) were added. The carbamate reaction was carried out at 80°C for 2 hours under a nitrogen atmosphere. Then, the reaction solution was maintained at 60°C, and 0.2 parts by weight of a 20% diethylene glycol (manufactured by ADEKA Corporation) solution of potassium octanoate (manufactured by Tokyo Chemical Industry Co., Ltd., hereinafter referred to as OctK) was added, and the isocyanurate reaction was carried out for 2 hours. Once the NCO content reached 41.5%, 0.3 parts by weight of JP-508 (manufactured by Jōhoku Chemical Industry Co., Ltd., acidic phosphate ester) was added to stop the reaction. Unreacted HDI was removed by thin-film distillation of the reaction solution at 130℃ × 0.04 kPa, yielding purified NCO-TR. NCO-TR is a transparent, viscous liquid with an NCO content of 21.1%, a number-average molecular weight of 697 (GPC), and a free HDI content of 0.2%. The average number of NCO functional groups calculated using Equation 1 based on the NCO content and number-average molecular weight is 3.5.

[0455] Average number of NCO functional groups = NCO content × number average molecular weight / (1000 × 4.2) ... (Equation 1)

[0456] <Determination conditions of number-average molecular weight using GPC>

[0457] • Measuring instrument: HLC-8220 (manufactured by Tosoh Corporation)

[0458] ·Column: TSKguardcolumn HXL-L (manufactured by Tosoh Corporation)

[0459] Particle size = 6μm, Size = 6mmID × 30cm × 4 pieces

[0460] • Support: Tetrahydrofuran (THF)

[0461] • Detector: Parallax Refraction

[0462] • Sample: 0.5% THF solution

[0463] Calibration line: Polystyrene.

[0464] <Preparation of Polyols>

[0465] Prepare the following: PEG-600 and PCDL-500, as well as trimethylolpropane:

[0466] PEG-600

[0467] Polyethylene glycol (initiator: ethylene glycol, EO adduct), number of terminal OH functional groups = 2, number average molecular weight = 600, average number of EO units per molecule = 13.2, EO unit content = 96%.

[0468] PCDL-500

[0469] A polycarbonate diol with a number average molecular weight of 500, obtained from 1,6-hexanediol (HG), 3-methyl-1,5-pentanediol (MPD), and diethyl carbonate (hereinafter referred to as DEC), with an HG / MPD mass ratio of 5 / 5.

[0470] The above-obtained NCO-TR 90.0 parts by mass and PEG-600 10.0 parts by mass were mixed and reacted at 95°C for 10 hours to obtain polyisocyanate (A) containing terminal NCO groups.

[0471] Alternatively, 70.0 parts by weight of PCDL-500 and 30.0 parts by weight of trimethylolpropane were mixed at 80°C for 1 hour to prepare a polyol (B) containing terminal OH groups.

[0472] Next, polyisocyanate (A) containing terminal NCO groups, polyol (B) at a temperature adjusted to 40°C, and dioctyltin dilaurate as a catalyst were added at a concentration of 0.01 parts by mass relative to the overall resin concentration, and mixed to prepare a polyurethane resin forming composition. After degassing the composition under reduced pressure of 5 mmHg, it was coated onto a heat-resistant polystyrene film (Oidys (registered trademark), manufactured by Kurashiki Textile Co., Ltd.), cured at 120°C for 30 minutes, and then dried at 80°C for 4 hours to obtain a polyurethane resin film with a thickness of 20 μm.

[0473] (Example 8)

[0474] As the restraint part, E5000 (manufactured by Toyobo Co., Ltd., thickness 38μm, glass transition temperature of PET film: 80°C) was used instead of TAC film. Otherwise, the optical laminate 8A was fabricated in the same manner as in Example 1.

[0475] (Example 9)

[0476] In the above-described <Coating Preparation> section on the formation of the damping section 1, the amount of acrylic graft copolymer particles added was changed to 2.2 parts by mass, and the amount of thermoplastic (meth)acrylic resin added was changed to 8.8 parts by mass. Otherwise, the optical laminate 9A was prepared in the same manner as in Example 1. The glass transition temperature of the damping section 1 is 10°C.

[0477] (Example 10)

[0478] In the above-described <Coating Preparation> section on the formation of the damping section 1, the amount of acrylic graft copolymer particles added was changed to 5.5 parts by mass, and the amount of thermoplastic (meth)acrylic resin added was changed to 5.5 parts by mass. Otherwise, the optical laminate 10A was prepared in the same manner as in Example 1. The glass transition temperature of the damping section 1 is 10°C.

[0479] (Example 11)

[0480] In the above-described <Coating Preparation> section on the formation of the damping section 1, the amount of acrylic graft copolymer particles added was changed to 9.9 parts by mass, and the amount of thermoplastic (meth)acrylic resin added was changed to 1.1 parts by mass. Otherwise, the optical laminate 11A was prepared in the same manner as in Example 1. The glass transition temperature of the damping section 1 is 10°C.

[0481] (Example 12)

[0482] Using a 15 μm thick thin film glass formed by the same method as described above for the fabrication of thin film glass, an optical laminate 12A was fabricated in the same manner as in Example 1.

[0483] (Example 13)

[0484] A 5 μm thick TAC film is fabricated using the same method as described above for the formation of the constraint portion. This film is used as the constraint portion. The thickness of the damping portion 1 is set to 10 μm, and the thickness of the damping portion 2 is set to 10 μm. Otherwise, the optical laminate 13A is fabricated in the same manner as in Example 1.

[0485] (Comparative Example 1)

[0486] Instead of thin-film glass, a transparent polyimide film (CPI, 30 μm thick) prepared as described below was used. Otherwise, the comparative optical laminate 1A was prepared in the same manner as in Example 1.

[0487] <Synthesis of Polyimide (PI) Resin>

[0488] A reactor and oil bath were prepared, equipped with a silica gel tube, a stirrer, and a thermometer attached to a separable flask. 75.52 g of 4,4'-(hexafluoroisopropylidene)phthalic anhydride (6FDA) and 54.44 g of 2,2'-bis(trifluoromethyl)-4,4'-diaminobiphenyl (TFMB) were added to the flask. The mixture was stirred at 400 rpm, and 519.84 g of N,N-dimethylacetamide (DMAc) was added simultaneously. Stirring continued until the contents of the flask became a homogeneous solution. Then, while adjusting the temperature inside the container to 20–30 °C using the oil bath, stirring was continued for 20 hours to allow the reaction to proceed and produce polyamic acid. After 30 minutes, the stirring speed was reduced to 100 rpm. After stirring for 20 hours, the reaction system temperature was restored to room temperature, and 649.8 g of DMAc was added to adjust the polymer concentration to 10% by mass. Then, 32.27 g of pyridine and 41.65 g of acetic anhydride were added, and the mixture was stirred at room temperature for 10 hours to induce imidization. The polyimide varnish was removed from the reaction vessel. The resulting polyimide varnish was added dropwise to methanol for reprecipitation. The resulting powder was heated and dried to remove the solvent, yielding a transparent polyimide resin in solid form. GPC analysis of the obtained polyimide resin showed a weight-average molecular weight of 360,000.

[0489] <Manufacturing of Transparent Polyimide Film (CPI)>

[0490] The polyimide resin (6FDA / TFMB = 100 / 100) obtained above was diluted with γ-butyrolactone (GBL) / DMAc at a ratio of 10 / 90 to prepare a polyimide varnish with a concentration of 15.7% by mass. The obtained polyimide varnish was filtered through a 10 μm mesh filter and then coated onto a smooth surface of a polyester substrate (Toyobo Co., Ltd., "A4100" (trade name)) with a self-supporting film thickness of 35 μm using a coater. It was dried at 50°C for 30 minutes, followed by drying at 140°C for 15 minutes. The resulting coating was then peeled off from the polyester substrate to obtain a self-supporting film. The self-supporting film was fixed to a metal frame and further dried at 200°C under atmospheric conditions for 40 minutes to obtain a transparent polyimide film with a thickness of 30 μm.

[0491] (Comparative Example 2)

[0492] As a restraint part, E5000 (manufactured by Toyobo Co., Ltd., 50μm thick, PET film) is used instead of TAC film, and shock-absorbing part 1 is not provided. Otherwise, the comparative optical laminate 2A is made in the same way as in Example 1.

[0493] (Comparative Example 3)

[0494] As the restraint part, E5000 (manufactured by Toyobo Co., Ltd., 75μm thick, PET film) was used instead of TAC film. Otherwise, the comparative optical laminate 3A was made in the same manner as Comparative Example 2.

[0495] (Comparative Example 4)

[0496] A 5 μm thick TAC film is fabricated using the same method as described above for the formation of the constraint portion. This film is used as the constraint portion. The thicknesses of the damping portion 1 and the damping portion 2 are set to 5 μm, and the thickness of the thin film glass is set to 6 μm. Otherwise, the comparative optical laminate 4A is fabricated in the same manner as in Example 1.

[0497] (Comparative Example 5)

[0498] A 22 μm thick TAC film was fabricated using the same method as described above for the formation of the constraint portion. This film was used as the constraint portion. The thickness of the damping portion 1 was set to 40 μm, the thickness of the damping portion 2 was set to 50 μm, and the thickness of the thin film glass was set to 45 μm. Otherwise, the comparative optical laminate 5A was fabricated in the same manner as in Example 1.

[0499] (Comparative Example 6)

[0500] As the shock-absorbing part 1, E5000 (manufactured by Toyobo Co., Ltd., 20μm thick, PET film) was used. Otherwise, the comparative optical laminate 6A was made in the same manner as in Example 1.

[0501] (Comparative Example 7)

[0502] The damping portion 1 is formed with a thickness of 20 μm using the same method as described above in the section on the formation of damping portion 2. Furthermore, the damping portion 2 is formed with a thickness of 25 μm using the same method as described above in the section on the formation of damping portion 1. In addition, the comparative optical laminate 7A is fabricated using the same method as in Example 1.

[0503] The configurations of each embodiment and comparative example are shown in Table 1 below.

[0504]

[0505] [evaluate]

[0506] <Bending Test>

[0507] The optical laminate obtained above was cut into pieces measuring 20mm in the TD direction and 110mm in the MD direction. Using a no-load U-shaped stretching tester (manufactured by Yuasa Systems Equipment Co., Ltd., DLDMLH-FS), with a bending radius of 1mm, it was bent 100 times at a rate of 1 time / second. At this time, the sample was fixed 10mm from both ends of the MD side, and the bent portion was 20mm × 90mm. After the bending process, the sample was placed on a flat surface with the bent inner side facing down, and the haze of the bent portion was measured using a haze meter (manufactured by Nippon Denshoku Kogyo Co., Ltd., model: NDH4000). The haze value before the bending test was set as A, and the haze value after the bending test was set as B. The difference between these values ​​(B-A) was calculated, and the results were evaluated according to the following criteria. If the evaluation score is 3 or higher, it is considered suitable for practical use.

[0508] 5: Less than 0.1

[0509] 4: Above 0.1 and less than 0.3

[0510] 3: Above 0.3 and less than 0.8

[0511] 2: 0.8 or higher and less than 1.1

[0512] 1:1.1 or above.

[0513] <Pen Drop Experiment>

[0514] The optical laminate obtained above is disposed on a bakelite substrate manufactured by Sunhayato Co., Ltd. with the thin-film glass in contact with the substrate and the restrained portion facing upwards. A ballpoint pen with a tip radius (R) of 0.35 mm and a weight (m) of 12 g is dropped onto the restrained portion while varying the drop height. The height at which the thin-film glass breaks is evaluated according to the following criteria. If the evaluation score is 3 or higher, it can be used practically.

[0515] 5. It will not break when dropped from 30cm.

[0516] 4. It will not break when dropped from 25cm.

[0517] 3: It will not break when dropped from 15cm.

[0518] 2: Microscopic examination revealed a tiny crack when the object fell from 15cm.

[0519] 1: Visually confirm the breakage when it falls from 15cm.

[0520] These evaluation results are shown in Table 2 below. In addition, Table 2 below shows the value of elastic modulus 1 / elastic modulus 2 when the stored elastic modulus of the restraint part is set to elastic modulus 1 (unit: GPa) and the stored elastic modulus of the damping part 1 is set to elastic modulus 2 (unit: GPa), and the value of B / A when the thickness of the thin film glass is set to A (unit: μm) and the total thickness of the restraint part, damping part 1 and damping part 2 is set to B (unit: μm).

[0521] [Table 2]

[0522]

[0523] As shown in Table 2 above, the optical laminate of the embodiments can be thinned, exhibiting excellent impact resistance and flexural properties. In the optical laminate of Comparative Example 3, which has a thickness similar to conventional optical laminates, the thin-film glass cracked during the bending test, making evaluation impossible.

[0524] This application is based on Japanese Patent Application No. 2022-016997, filed on February 7, 2022, the disclosure of which is incorporated herein by reference in its entirety.

Claims

1. An optical laminate, comprising, in sequence, a constraint portion, a damping portion 1, a damping portion 2, and a thin film glass with a thickness in the range of 10–40 μm, wherein, When the tanδ of the constraint part is set as tanδ1, the tanδ of the damping part 1 is set as tanδ2, and the tanδ of the damping part 2 is set as tanδ3, the tanδ1, the tanδ2, and the tanδ3 satisfy the following relationship (1). ， The tanδ is the loss tangent, a value measured using a dynamic viscoelasticity measuring device. The tanδ1 is 0.001 to 0.

1. The tanδ² is 0.01–0.

3. The tanδ3 is 0.01 to 1.0; The thickness of the constraint part is 5–60 μm. The thickness of the damping part 1 is 10-60 μm. The thickness of the damping part 2 is 5-60 μm; Let the thickness of the thin-film glass be A. When the total thickness of the constraint part, the damping part 1, and the damping part 2 is set to B, The following relationship (3) is satisfied, where the units of A and B are μm. 。 2. The optical laminate according to claim 1, wherein, When the stored elastic modulus of the constraint part is set as elastic modulus 1 and the stored elastic modulus of the damping part 1 is set as elastic modulus 2, the elastic modulus 1 and the elastic modulus 2 satisfy the following relationship (2), where the units of elastic modulus 1 and elastic modulus 2 are GPa. 。 3. The optical laminate according to claim 1 or 2, wherein, The constraint part and the shock-absorbing part 1 are membranes.

4. The optical laminate according to claim 1 or 2, wherein, The shock-absorbing part 1 is a film comprising at least a thermoplastic (meth)acrylic resin and a graft copolymer.

5. The optical laminate according to claim 3, wherein, The shock-absorbing part 1 is a film comprising at least a thermoplastic (meth)acrylic resin and a graft copolymer.

6. The optical laminate according to claim 4, wherein, The content of the graft copolymer relative to the total mass of the membrane is 60-90% by mass.

7. The optical laminate according to claim 5, wherein, The content of the graft copolymer relative to the total mass of the membrane is 60-90% by mass.

8. A display device comprising: Light-emitting devices, and The optical laminate according to any one of claims 1 to 7; The constraint portion of the optical laminate is positioned closest to the recognition side.

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