WO2024095890A1 - Stratifié et dispositif d'affichage - Google Patents

Stratifié et dispositif d'affichage Download PDF

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Publication number
WO2024095890A1
WO2024095890A1 PCT/JP2023/038692 JP2023038692W WO2024095890A1 WO 2024095890 A1 WO2024095890 A1 WO 2024095890A1 JP 2023038692 W JP2023038692 W JP 2023038692W WO 2024095890 A1 WO2024095890 A1 WO 2024095890A1
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Prior art keywords
optical film
meth
acrylate
range
mass
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PCT/JP2023/038692
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English (en)
Japanese (ja)
Inventor
啓人 小長
奈々恵 藤枝
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コニカミノルタ株式会社
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Publication of WO2024095890A1 publication Critical patent/WO2024095890A1/fr

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B17/00—Layered products essentially comprising sheet glass, or glass, slag, or like fibres
    • B32B17/06—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material
    • B32B17/10—Layered products essentially comprising sheet glass, or glass, slag, or like fibres comprising glass as the main or only constituent of a layer, next to another layer of a specific material of synthetic resin
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/02—Physical, chemical or physicochemical properties
    • B32B7/022—Mechanical properties
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G—PHYSICS
    • G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
    • G09F—DISPLAYING; ADVERTISING; SIGNS; LABELS OR NAME-PLATES; SEALS
    • G09F9/00—Indicating arrangements for variable information in which the information is built-up on a support by selection or combination of individual elements

Definitions

  • the present invention relates to a laminate and a display device. More specifically, the present invention relates to a laminate that combines impact resistance and flexibility in the glass layer.
  • Flexible displays consist of a display unit and a cover unit that protects the display unit.
  • the substrate used in the cover unit must be flexible. For this reason, consideration is being given to changing from the conventionally used glass substrate to a resin substrate, or to making the glass substrate itself thinner.
  • thin-film glass Ultra Thin Glass: UTG
  • UTG Ultra Thin Glass
  • thin-film glass has the problem that it is vulnerable to impacts and easily breaks.
  • cover glass units that can withstand the impacts that occur when using a pen. From this perspective, cover glass units are required to have higher impact resistance than ever before.
  • Patent Literature 1 discloses a technology relating to a display film including a glass layer and an energy dissipation layer, and states that an intermediate adhesive layer may be provided between the glass layer and the energy dissipation layer for the purpose of fixing the energy dissipation layer to the glass layer.
  • the display film cannot withstand high impacts, and that in order to withstand high impacts, the display film must be made relatively thick.
  • Patent Document 2 discloses technology relating to an adhesive layer for an organic EL display device that has excellent resistance to impact from a fall.
  • the cover glass unit has excellent resistance to impact from a fall, but it also becomes relatively thick. For this reason, it has been found to be difficult to obtain a cover glass unit that combines impact resistance and flexibility.
  • the present invention was made in consideration of the above problems and circumstances, and the problem to be solved is to provide a laminate and a display device that achieves both impact resistance and flexibility in the glass layer.
  • the present inventors have investigated the causes of the above problems in order to solve the above problems. As a result, they have found that in a laminate having a glass layer, an elastic layer, and an optical film, by setting the storage modulus at 25°C of the elastic layer within a specific range, and by making the optical film contain rubber particles, and setting the value of the ratio of the loss tangents at 25°C of the elastic layer and the optical film within a specific range, it is possible to provide a laminate in which the glass layer has both impact resistance and flexibility, and have arrived at the present invention. That is, the above-mentioned problems of the present invention are solved by the following means.
  • the storage modulus of the elastic layer at 25° C. is within a range of 0.5 to 10.0 MPa;
  • the optical film contains rubber particles,
  • the ratio of the loss tangents (tan ⁇ 1 /tan ⁇ 2 ) satisfies the following formula (1): 1.0 ⁇ tan ⁇ 1 /tan ⁇ 2 ⁇ 3.0.
  • a laminate comprising:
  • a display device comprising the laminate according to claim 1 or 2.
  • the above-mentioned means of the present invention make it possible to provide a laminate and a display device that combines impact resistance and flexibility in the glass layer.
  • the laminate used in the cover glass unit is configured with a thick layer with a relatively low storage modulus underneath the thin glass.
  • the thin glass can be damaged. This is thought to occur when, during pen input, the outward tensile stress acting on the back surface of the thin glass (the back surface when the surface that comes into contact with the pen is considered the front surface) is not suppressed, causing the thin glass to bend.
  • a film made of polyethylene terephthalate (PET) or polymethyl methacrylate (PMMA) is further provided under the thin film glass.
  • PET polyethylene terephthalate
  • PMMA polymethyl methacrylate
  • the outward tensile stress acting on the back surface of the thin glass during pen input can be suppressed, and bending of the thin glass can be prevented.
  • the outward tensile stress acting on the back surface of the thin glass can be further suppressed.
  • the layer with a relatively high storage modulus thinner, the distance between the thin glass film and the optical film becomes shorter, which is believed to increase the effect of suppressing tensile stress and better prevent the thin glass film from warping.
  • the loss tangent (tan ⁇ ) of the optical film relatively large, it is possible to make it difficult for an impact to be transmitted to the internal module, and it is believed that damage to the internal module can be prevented. It is believed that these features provide sufficient impact resistance whether the area receiving the impact force is relatively small or large.
  • the optical film contains rubber particles, which makes it possible to make the loss tangent (tan ⁇ ) relatively large and to reduce the thickness of the film. This allows the thickness of the laminate to be relatively thin, which is believed to result in sufficient flexibility.
  • FIG. 1 is a cross-sectional view of a basic layer structure of a laminate of the present invention. Schematic diagram showing an example of a method for producing thin glass
  • the laminate of the present invention is a laminate having a glass layer, an elastic layer and an optical film, wherein the elastic layer has a storage modulus at 25° C. in the range of 0.5 to 10.0 MPa, the optical film contains rubber particles, and when the loss tangents at 25° C. of the elastic layer and the optical film are tan ⁇ 1 and tan ⁇ 2 , respectively, the ratio of the loss tangents (tan ⁇ 1 /tan ⁇ 2 ) satisfies the following formula (1): 1.0 ⁇ tan ⁇ 1 /tan ⁇ 2 ⁇ 3.0 It is characterized by: This feature is a technical feature common to or corresponding to the following embodiments.
  • the storage modulus of the elastic layer at 25°C is within the range of 1.2 to 8.0 MPa.
  • the ratio of loss tangents (tan ⁇ 1 /tan ⁇ 2 ) satisfies the above formula (2).
  • the content of the rubber particles is preferably within the range of 10 to 80 mass % with respect to the total mass of the optical film.
  • the optical film contains a thermoplastic (meth)acrylic resin.
  • the thickness of the glass layer is within the range of 10 to 30 ⁇ m.
  • the thickness of the elastic layer is within the range of 2 to 15 ⁇ m.
  • the display device of the present invention is characterized by having the laminate of the present invention.
  • the display device of the present invention is a display device that includes the laminate of the present invention, and that the glass layer is disposed on the outer side of the display device relative to the optical film.
  • the laminate of the present invention is a laminate having a glass layer, an elastic layer, and an optical film, wherein the elastic layer has a storage modulus at 25° C. in the range of 0.5 to 10.0 MPa, the optical film contains rubber particles, and when the loss tangents at 25° C. of the elastic layer and the optical film are tan ⁇ 1 and tan ⁇ 2 , respectively, the ratio of the loss tangents (tan ⁇ 1 /tan ⁇ 2 ) satisfies the following formula (1): Formula (1): 1.0 ⁇ tan ⁇ 1 /tan ⁇ 2 ⁇ 3.0
  • FIG. 1 is a cross-sectional view of the basic layer structure of the laminate of the present invention.
  • the laminate 10 has a glass layer 1, an elastic layer 2, and an optical film 3. If necessary, other layers may be disposed between the layers.
  • the order in which the layers are disposed is not particularly limited, but it is preferable from the viewpoint of exerting the effect to dispose the elastic layer 2 between the glass layer 1 and the optical film 3.
  • the boundary between the elastic layer and the optical film does not necessarily need to be clear, and the layer structure may be such that the elastic layer and the optical film are integrated.
  • the loss tangents at 25° C. of the upper 30% and lower 30% in the thickness direction of the film are tan ⁇ 3 and tan ⁇ 4 , respectively.
  • the ratio of the loss tangents (tan ⁇ 3 /tan ⁇ 4 ) satisfies the following formula (3), the present invention is applicable.
  • viscoelastic body An object that has both elastic and viscous properties is called a "viscoelastic body.”
  • the properties of a viscoelastic body can be expressed by the dynamic elastic modulus. That is, the "dynamic modulus of elasticity" is a physical quantity that indicates the properties of an object as a viscoelastic body, and is defined as the ratio of an oscillating stress to the strain caused by the stress.
  • the dynamic modulus of elasticity is generally expressed as a complex number (also called the “complex modulus") and can be decomposed into two terms: the "storage modulus” which corresponds to the real part, and the "loss modulus” which corresponds to the imaginary part.
  • the storage modulus corresponds to the portion of the material that is stored as elastic energy when it deforms, and is an index of the degree of hardness. In other words, the higher the storage modulus value, the harder the object is, and the lower the storage modulus value, the softer the object is.
  • the loss modulus corresponds to the portion of the lost energy dissipated due to internal friction etc. when a material is deformed, and is an index of the degree of viscosity.
  • Loss tangent loss modulus / storage modulus
  • Loss tangent loss modulus / storage modulus
  • the laminate of the present invention has a glass layer, an elastic layer, and an optical film. Each layer will be described below.
  • the glass layer according to the present invention is preferably a thin glass.
  • materials for the thin glass include lithium aluminosilicate glass, soda-lime glass, borosilicate glass, alkali metal aluminosilicate glass, and aluminosilicate glass with a low alkali content.
  • the thin film glass is preferably an alkali-free glass that contains substantially no alkali components.
  • the content of alkali components is preferably 1000 ppm by mass or less, more preferably 500 ppm by mass or less, and even more preferably 300 ppm by mass or less, relative to the total mass of the thin film glass.
  • Thin glass can be produced by a commonly known method, such as a float method, a down-draw method, an overflow down-draw method, etc.
  • the overflow down-draw method or the float method is preferred because the surface of the thin glass does not come into contact with the forming member during production, and the surface of the obtained thin glass is less likely to be scratched.
  • the float method is preferred from the viewpoint of making it possible to make the thickness of the thin glass less than 200 ⁇ m.
  • the thinner the glass the weaker it is and the more susceptible it is to breakage, making it difficult to handle and process thin-film glass on its own.
  • a thicker support substrate hereafter also referred to as a "carrier substrate”
  • peeling off the support substrate as a post-processing step
  • FIG. 2 is a schematic diagram showing an example of a method for producing thin-film glass.
  • Step 1 in step 1, a thin film glass 22 is prepared so that a first surface of the thin film glass is in contact with a carrier substrate 21 having a bonding surface. Then, a contact film 23 having adhesive force (hereinafter also referred to as a "contact film”) is pressure-bonded to a second surface opposite to the first surface.
  • a contact film 23 having adhesive force hereinafter also referred to as a "contact film”
  • the thin-film glass material is poured to the desired thickness onto a carrier substrate 21 that has sufficient strength and a thickness that is easy to process. This creates a first surface of the thin-film glass 22 that is in contact with the carrier substrate 21. After that, a contact film 23 is pressed onto a second surface on the opposite side to the first surface.
  • Step 2 As shown in FIG. 2, in step 2, the thin glass 22 is peeled off from the carrier substrate 21 by the contact film 23 having high adhesive strength.
  • Step 3 in step 3, a weakening treatment (electromagnetic radiation irradiation 24) is performed to weaken the adhesive strength of the contact film, thereby removing the contact film 23 from the second surface of the thin glass 22.
  • the contact film 23 is used to safely hold the thin-film glass 22, thereby protecting the thin-film glass 22.
  • the exposed surface of the thin-film glass 22 can be protected from, for example, mechanical damage, and can be handled safely and easily.
  • Examples of materials for the contact film include polyolefins (PO) such as polyethylene terephthalate (PET) and polyethylene (PE).
  • PO polyolefins
  • PET polyethylene terephthalate
  • PE polyethylene
  • the contact film is usually adhered to the thin glass by an adhesive layer made of an adhesive provided on one side of the substrate.
  • the contact film may also be adhered directly to the thin glass by the adhesive properties of the contact film itself.
  • the adhesive strength between the contact film and the second surface of the thin film glass is appropriately selected so that the peeling device transmits sufficient force to peel the thin film glass from the carrier substrate.
  • the contact film is preferably in the form of a foil or tape. By forming it into a foil or tape, it can be wound into a roll.
  • the thickness of the contact film is preferably 50 ⁇ m or more, more preferably 80 ⁇ m or more, more preferably 125 ⁇ m or more, and particularly preferably 150 ⁇ m or more.
  • the thin glass is preferably fabricated on a carrier substrate by the aforementioned downdraw method, overflow downdraw method, or float method.
  • the thickness of the carrier substrate is preferably 100 ⁇ m or more, more preferably 300 ⁇ m or more, and even more preferably 500 ⁇ m or more. Furthermore, the width of the carrier substrate is preferably 3 inches or more (1 inch is 2.54 cm), more preferably 6 inches or more, even more preferably 8 inches or more, and particularly preferably 12 inches or more.
  • the carrier substrate is preferably equal to or larger than the first generation glass substrate size, for example, second to eighth generation sizes. Alternatively, it may be even larger, for example, 1x1m to 3x3m.
  • the carrier substrate may be of various shapes, such as rectangular, elliptical, circular, etc.
  • the thin glass film, together with the contact film, is peeled off from the carrier substrate by the adhesive force of the contact film.
  • the contact film is then peeled off, leaving a single thin glass film.
  • the adhesive strength of the contact film Before peeling the contact film from the thin glass, it is preferable to weaken the adhesive strength of the contact film by subjecting it to a treatment to weaken its adhesive strength. Specifically, it is preferable to reduce the adhesive strength to 0.5 N/25 mm or less.
  • electromagnetic radiation such as infrared, ultraviolet, or visible light
  • the electromagnetic radiation may be narrowband or may cover a wider band depending on the adhesive material used. It may also be laser radiation.
  • Some commercially available adhesive materials can be at least partially deactivated by exposure to electromagnetic radiation and can be used as contact films.
  • heat treatment may be used as a weakening treatment.
  • the electromagnetic radiation is preferably applied from the outer surface of the contact film, i.e., the side to which the thin glass is not adhered.
  • An example of a contact film is "NDS4150-20" (manufactured by Dao Ming Optical Co., Ltd.).
  • a corresponding weakening treatment is exposure to ultraviolet light with a wavelength of 365 nm.
  • the thickness of the thin film glass is preferably within the range of 10 to 50 ⁇ m.
  • the thickness of the thin film glass is more preferably within the range of 10 to 40 ⁇ m, and further preferably within the range of 10 to 30 ⁇ m.
  • the elastic layer according to the present invention is characterized in that it has a storage modulus in the range of 0.5 to 10.0 MPa at 25° C.
  • the loss tangents of the elastic layer and the optical film according to the present invention are tan ⁇ 1 and tan ⁇ 2 , respectively, the ratio of the loss tangents (tan ⁇ 1 /tan ⁇ 2 ) satisfies the above formula (1).
  • the elastic layer according to the present invention is not particularly limited as long as the storage modulus at 25° C. is within the range of 0.5 to 10.0 MPa and the loss tangent satisfies the above formula (1).
  • the elastic layer according to the present invention is preferably made of a pressure-sensitive adhesive.
  • the elastic layer according to the present invention may be in the form of a film that can be wound up, or in the form of a coating layer.
  • the coating layer is formed by applying an adhesive onto an adjacent layer and then curing the applied adhesive.
  • the adhesive is not particularly limited as long as the storage modulus of the elastic layer to be produced at 25°C is within the range of 0.5 to 10.0 MPa and the loss tangent satisfies the above formula (1).
  • the adhesive include rubber-based adhesives, acrylic-based adhesives, silicone-based adhesives, urethane-based adhesives, vinyl alkyl ether-based adhesives, polyvinyl alcohol-based adhesives, polyvinyl pyrrolidone-based adhesives, polyacrylamide-based adhesives, and cellulose-based adhesives.
  • acrylic-based adhesives are preferred.
  • Acrylic-based adhesives have excellent transparency and excellent adhesive properties (adhesion, cohesion, and adhesion). They also have excellent weather resistance, heat resistance, and the like.
  • the term "acrylic pressure-sensitive adhesive” refers to a pressure-sensitive adhesive that contains an acrylic polymer as a base polymer.
  • the elastic layer made of an acrylic adhesive is preferably a layer formed by UV-curing (UV-polymerizing) an UV-curable acrylic adhesive. Note that, by UV-curing (UV-polymerizing) an UV-curable acrylic adhesive, a (meth)acrylic polymer is generated.
  • the "ultraviolet-curable acrylic adhesive” preferably contains a monomer component containing alkyl (meth)acrylate or a partial polymer of the monomer component, an ultraviolet absorber, a photopolymerization initiator having an absorption band at wavelengths of 400 nm or more, etc.
  • the UV-curable acrylic pressure-sensitive adhesive has as its base polymer a (meth)acrylic polymer obtained by UV-curing (UV-polymerizing) a monomer component containing an acrylate or a partial polymer of the monomer component.
  • the alkyl (meth)acrylate contained in the monomer component and other monomers that may be contained will be described below.
  • the other monomers that may be contained are preferably monofunctional monomers, but may also be polyfunctional monomers.
  • alkyl (meth)acrylate refers to acrylic and methacrylic, and is a general term for both.
  • alkyl (meth)acrylate refers to alkyl acrylate and alkyl methacrylate, and is a general term for both.
  • the alkyl (meth)acrylate according to the present invention is preferably an alkyl (meth)acrylate having a linear or branched alkyl group having 1 to 24 carbon atoms at the ester terminal. These may be used alone or in combination of two or more.
  • alkyl (meth)acrylates include alkyl (meth)acrylates having a branched alkyl group having 4 to 9 carbon atoms. Specific 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. These may be used alone or in combination of two or more.
  • the content of alkyl (meth)acrylate 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, based on the total mass of the monomer components.
  • Examples of monofunctional copolymerizable monomers (monofunctional monomers) other than alkyl (meth)acrylates include cyclic nitrogen-containing monomers.
  • the cyclic nitrogen-containing monomer is not particularly limited as long as it has a polymerizable functional group having an unsaturated double bond such as a (meth)acryloyl group or a vinyl group, and has a cyclic nitrogen structure.
  • the cyclic nitrogen structure is preferably one having a nitrogen atom in the cyclic structure.
  • Examples of the cyclic nitrogen-containing monomer include lactam-based vinyl monomers such as N-vinyl-2-pyrrolidone, N-vinyl- ⁇ -caprolactam, and methylvinylpyrrolidone, and vinyl-based monomers having a nitrogen-containing heterocycle such as vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole, vinyloxazole, and vinylmorpholine.
  • examples of the monomers include (meth)acrylic monomers having a heterocycle such as a morpholine ring, a piperidine ring, a pyrrolidine ring, and a piperazine ring. Specific examples include N-acryloylmorpholine, N-acryloylpiperidine, N-methacryloylpiperidine, and N-acryloylpyrrolidine.
  • lactam vinyl monomers are preferred.
  • the content of the cyclic nitrogen-containing monomer is preferably 0.5 to 50 mass%, more preferably 0.5 to 40 mass%, and even more preferably 0.5 to 30 mass%, based on the total mass of the monomer components.
  • a monofunctional monomer is a hydroxyl group-containing monomer.
  • the hydroxyl group-containing monomer has a polymerizable functional group with an unsaturated double bond, such as a (meth)acryloyl group or a vinyl group, and also has a hydroxyl group.
  • hydroxy group-containing monomer examples include hydroxyalkyl (meth)acrylates such as 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, and 12-hydroxylauryl (meth)acrylate; and hydroxyalkyl cycloalkane (meth)acrylates such as (4-hydroxymethylcyclohexyl)methyl (meth)acrylate.
  • hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxy
  • hydroxyethyl (meth)acrylamide examples include hydroxyethyl (meth)acrylamide, allyl alcohol, 2-hydroxyethyl vinyl ether, 4-hydroxybutyl vinyl ether, and diethylene glycol monovinyl ether.
  • hydroxyalkyl (meth)acrylates are preferred. These may be used alone or in combination of two or more.
  • the content of the hydroxyl group-containing monomer is preferably within the range of 1 to 30% by mass, more preferably within the range of 2 to 27% by mass, and even more preferably within the range of 3 to 25% by mass, based on the total mass of the monomer components.
  • monofunctional monomers include carboxyl group-containing monomers and monomers having cyclic ether groups.
  • carboxyl group-containing monomer there are no particular limitations on the carboxyl group-containing monomer, so long as it has a polymerizable functional group with an unsaturated double bond, such as a (meth)acryloyl group or a vinyl group, and also has a carboxyl group.
  • carboxy group-containing monomer examples include (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, isocrotonic acid, etc.
  • itaconic acid or maleic acid may be an anhydride thereof.
  • acrylic acid or methacrylic acid is preferred, and acrylic acid is more preferred. These may be used alone or in combination of two or more.
  • the monomer having a cyclic ether group is not particularly limited as long as it has a polymerizable functional group having an unsaturated double bond, such as a (meth)acryloyl group or a vinyl group, and also has a cyclic ether group, such as an epoxy group or an oxetane group.
  • Examples of epoxy group-containing monomers include glycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate glycidyl ether, etc.
  • Examples of oxetane group-containing monomers include 3-oxetanylmethyl (meth)acrylate, 3-methyl-oxetanylmethyl (meth)acrylate, 3-ethyl-oxetanylmethyl (meth)acrylate, 3-butyl-oxetanylmethyl (meth)acrylate, 3-hexyl-oxetanylmethyl (meth)acrylate, etc. These may be used alone or in combination of two or more. Wear.
  • the content of the carboxyl group-containing monomer or the monomer having a cyclic ether group is preferably 30% by mass or less, more preferably 27% by mass or less, and even more preferably 25% by mass or less, based on the total mass of the monomer components.
  • alkyl (meth)acrylates represented by CH 2 ⁇ C(R 1 )COOR 2 (R 1 represents a hydrogen atom or a methyl group, and R 2 represents a substituted alkyl group having 1 to 3 carbon atoms or a cyclic cycloalkyl group).
  • alkyl (meth)acrylate represented by CH 2 ⁇ C(R 1 )COOR 2 examples include phenoxyethyl (meth)acrylate, benzyl (meth)acrylate, cyclohexyl (meth)acrylate, 3,3,5-trimethylcyclohexyl (meth)acrylate, and isobornyl (meth)acrylate. These may be used alone or in combination of two or more.
  • the content of the alkyl (meth)acrylate represented by the above CH 2 ⁇ C(R 1 )COOR 2 is preferably 50 mass% or less, more preferably 45 mass% or less, and even more preferably 40 mass% or less, based on the total mass of the monomer components.
  • monofunctional monomers include, for example, vinyl acetate, vinyl propionate, styrene, ⁇ -methylstyrene; glycol-based acrylic ester monomers such as polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, methoxyethylene glycol (meth)acrylate, and methoxypolypropylene glycol (meth)acrylate; acrylic ester monomers such as tetrahydrofurfuryl (meth)acrylate, fluorine (meth)acrylate, silicone (meth)acrylate, and 2-methoxyethyl acrylate; amide group-containing monomers, amino group-containing monomers, imide group-containing monomers, N-acryloylmorpholine, and vinyl ether monomers. Also included are monomers having a cyclic structure such as terpene (meth)acrylate and dicyclopentanyl (meth)acrylate.
  • silane-based monomers containing a silicon atom examples include 3-acryloxypropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 4-vinylbutyltrimethoxysilane, 4-vinylbutyltriethoxysilane, 8-vinyloctyltrimethoxysilane, 8-vinyloctyltriethoxysilane, 10-methacryloyloxydecyltrimethoxysilane, 10-acryloyloxydecyltrimethoxysilane, 10-methacryloyloxydecyltriethoxysilane, and 10-acryloyloxydecyltriethoxysilane.
  • monomers may contain polyfunctional monomers as necessary in order to adjust the cohesive strength of the elastic layer.
  • polyfunctional monomer there are no particular limitations on the polyfunctional monomer, so long as it is a monomer that has at least two polymerizable functional groups with unsaturated double bonds, such as (meth)acryloyl groups or vinyl groups.
  • polyfunctional monomers include ester compounds of polyhydric alcohols and (meth)acrylic acid such as (poly)ethylene glycol di(meth)acrylate, (poly)propylene 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 (meth)acrylate, vinyl (meth)acrylate, divinylbenzene, epoxy acrylate, polyester acrylate, urethane tri(
  • trimethylolpropane tri(meth)acrylate hexanediol di(meth)acrylate, or dipentaerythritol hexa(meth)acrylate is preferred. These may be used alone or in combination of two or more.
  • the content of the polyfunctional monomer varies depending on the molecular weight, the number of functional groups, etc., but is preferably 3 mass% or less, more preferably 2 mass% or less, and even more preferably 1 mass% or less, relative to the total mass of the monofunctional monomer.
  • the content of the polyfunctional monomer is preferably 0.001 mass% or more.
  • the monomer component may contain a partial polymer of the above monomer component.
  • the ultraviolet-curable acrylic pressure-sensitive adhesive according to the present invention preferably contains an ultraviolet absorbing agent.
  • an ultraviolet absorbing agent By containing an ultraviolet absorbing agent, the influence of ultraviolet rays on the internal module (display unit) can be reduced.
  • the ultraviolet absorbing agent is not particularly limited, and examples thereof include triazine-based ultraviolet absorbing agents, benzotriazole-based ultraviolet absorbing agents, benzophenone-based ultraviolet absorbing agents, oxybenzophenone-based ultraviolet absorbing agents, salicylic acid ester-based ultraviolet absorbing agents, and cyanoacrylate-based ultraviolet absorbing agents. These may be used alone or in combination of two or more.
  • triazine-based UV absorbers are preferred, and triazine-based UV absorbers having two or less hydroxyl groups per molecule are more preferred.
  • Benzotriazole-based UV absorbers are also preferred, and benzotriazole-based UV absorbers having one benzotriazole skeleton per molecule are more preferred.
  • These UV absorbers are preferably used because they have good solubility in the monomer components and high UV absorption capacity at wavelengths around 380 nm.
  • the content of the UV absorber is preferably within the range of 0.1 to 5% by mass, and more preferably within the range of 0.5 to 3% by mass, based on the total mass of the monomer components. By being within the above range, it is possible to impart sufficient UV absorption function to the elastic layer and prevent interference with UV curing (UV polymerization).
  • the ultraviolet-curable acrylic pressure-sensitive adhesive according to the present invention preferably contains a photopolymerization initiator (A) (hereinafter also simply referred to as "photopolymerization initiator (A)”) having an absorption band at a wavelength of 400 nm or more.
  • A photopolymerization initiator
  • an ultraviolet-curing adhesive contains an ultraviolet absorber
  • ultraviolet curing ultraviolet curing
  • ultraviolet light is absorbed by the ultraviolet absorber
  • polymerization cannot be sufficiently performed.
  • the ultraviolet-curing acrylic adhesive of the present invention contains a photopolymerization initiator having an absorption band at wavelengths of 400 nm or more, and therefore can be sufficiently polymerized despite containing an ultraviolet absorber.
  • photopolymerization initiator (A) examples include bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide (commercially available products include, for example, "Omnirad (registered trademark) 819" (manufactured by IGM Resins B.V.)). Also included are 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (commercially available products include, for example, "Omnirad (registered trademark) TPO H” (manufactured by IGM Resins B.V.)).
  • the photopolymerization initiator (A) may be used alone or in combination of two or more types.
  • the content of the photopolymerization initiator (A) is not particularly limited, but is preferably less than the content of the ultraviolet absorber.
  • the content is preferably within the range of 0.005 to 1 mass% relative to the total mass of the monomer components, and more preferably within the range of 0.02 to 0.5 mass%. By being within the above range, ultraviolet curing (ultraviolet polymerization) can be sufficiently promoted.
  • the ultraviolet-curable acrylic adhesive of the present invention preferably further contains a photopolymerization initiator (B) (hereinafter, simply referred to as "photopolymerization initiator (B)”) that has an absorption band at a wavelength of less than 400 nm. It is preferable that the photopolymerization initiator (B) does not have an absorption band at a wavelength of 400 nm or more.
  • a photopolymerization initiator (B) hereinafter, simply referred to as "photopolymerization initiator (B)
  • photopolymerization initiator (B) that has an absorption band at a wavelength of less than 400 nm. It is preferable that the photopolymerization initiator (B) does not have an absorption band at a wavelength of 400 nm or more.
  • the photopolymerization initiator (B) is not particularly limited as long as it generates radicals by ultraviolet light and initiates photopolymerization, and has an absorption band at a wavelength of less than 400 nm.
  • the photopolymerization initiator (B) a commonly used photopolymerization initiator can be suitably used.
  • benzoin ether-based photopolymerization initiators acetophenone-based photopolymerization initiators, ⁇ -ketol-based photopolymerization initiators, photoactive oxime-based photopolymerization initiators, benzoin-based photopolymerization initiators, benzyl-based photopolymerization initiators, benzophenone-based photopolymerization initiators, ketal-based photopolymerization initiators, thioxanthone-based photopolymerization initiators, acylphosphine oxide-based photopolymerization initiators, etc.
  • the photopolymerization initiator (B) may be used alone or in combination of two or more kinds.
  • the content of the photopolymerization initiator (B) is preferably within the range of 0.005 to 0.5% by mass, and more preferably within the range of 0.02 to 0.1% by mass, based on the total mass of the monomer components.
  • the photopolymerization initiator (B) is first added to the monomer components. Then, it is preferable to add the photopolymerization initiator (A) and the UV absorber to the partially polymerized monomer components (prepolymer composition) that have been partially polymerized by irradiating UV light, and perform UV curing (UV polymerization).
  • UV curing UV polymerization
  • the ultraviolet-curable acrylic pressure-sensitive adhesive according to the present invention may further contain a silane coupling agent, a crosslinking agent, and the like.
  • Silane coupling agents include, for example, epoxy group-containing silane coupling agents such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; amino group-containing silane coupling agents such as 3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylidene)propylamine, and N-phenyl- ⁇ -aminopropyltrimethoxysilane; (meth)acrylic group-containing silane coupling agents such as 3-acryloxypropyltrimethoxysilane and 3-methacryloxypropyltriethoxysilane; and isocyan
  • the content of the silane coupling agent is preferably 1% by mass or less, more preferably in the range of 0.01 to 1% by mass, and even more preferably in the range of 0.02 to 0.6% by mass, based on the total mass of the monomer components.
  • crosslinking agent examples include isocyanate-based crosslinking agents, epoxy-based crosslinking agents, silicone-based crosslinking agents, oxazoline-based crosslinking agents, aziridine-based crosslinking agents, silane-based crosslinking agents, alkyl etherified melamine-based crosslinking agents, metal chelate-based crosslinking agents, peroxides, etc.
  • isocyanate-based crosslinking agents are preferred. These may be used alone or in combination of two or more.
  • An isocyanate crosslinking agent is a compound that has two or more isocyanate groups (including isocyanate regenerating functional groups in which the isocyanate group is temporarily protected by a blocking agent or by polymerization, etc.) in one molecule.
  • isocyanate crosslinking agents include aromatic isocyanates such as tolylene diisocyanate and xylylene diisocyanate; alicyclic isocyanates such as isophorone diisocyanate; and aliphatic isocyanates such as hexamethylene diisocyanate.
  • the content of the crosslinking agent is preferably 5% by mass or less, more preferably in the range of 0.01 to 5% by mass, even more preferably in the range of 0.01 to 4% by mass, and particularly preferably in the range of 0.02 to 3% by mass, based on the total mass of the monomer components.
  • the UV-curable acrylic adhesive of the present invention may contain other additives as appropriate in addition to the above components depending on the application.
  • additives include tackifiers (e.g., rosin derivative resins, polyterpene resins, petroleum resins, oil-soluble phenolic resins, etc. that are solid, semi-solid, or liquid at room temperature); fillers such as hollow glass balloons; plasticizers; anti-aging agents; antioxidants, etc.
  • the viscosity of the UV-curable acrylic adhesive according to the present invention is preferably adjusted to a level suitable for application.
  • the viscosity can be adjusted, for example, by adding various polymers such as thickening additives, polyfunctional monomers, etc., or by partially polymerizing the monomer components in the UV-curable acrylic adhesive.
  • the partial polymerization may be carried out before or after adding various polymers such as thickening additives, polyfunctional monomers, etc.
  • the viscosity of the ultraviolet-curable acrylic adhesive according to the present invention varies depending on the content of additives, etc. Therefore, the polymerization rate when the monomer components in the ultraviolet-curable acrylic adhesive are partially polymerized cannot be uniquely determined.
  • the polymerization rate is preferably 20% or less, more preferably within the range of 3 to 20%, and even more preferably within the range of 5 to 15%.
  • the viscosity can be adjusted to a level suitable for application work.
  • the elastic layer can be produced by applying an ultraviolet-curing acrylic adhesive onto an adjacent layer, and irradiating it with ultraviolet light to cause ultraviolet curing (ultraviolet polymerization).
  • an ultraviolet-curable acrylic adhesive may be applied onto a substrate, and then ultraviolet light may be irradiated to effect ultraviolet curing (ultraviolet polymerization), thereby forming a film-like elastic layer.
  • the substrate is not particularly limited, and examples include release films, transparent resin films, etc.
  • release films include release resin films such as polyethylene, polypropylene, polyethylene terephthalate, and polyester films; porous materials such as paper, cloth, and nonwoven fabric; and thin materials such as nets, foam sheets, metal foils, and laminates of these.
  • resin films are preferred from the viewpoint of excellent surface smoothness.
  • release resin films include polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polybutylene terephthalate film, polyurethane film, ethylene-vinyl acetate copolymer film, etc.
  • the thickness of the release film is preferably within the range of 5 to 200 ⁇ m, and more preferably within the range of 5 to 100 ⁇ m.
  • the release film is preferably subjected to a release treatment using a silicone-based, fluorine-based, long-chain alkyl-based or fatty acid amide-based release agent as necessary. It is also preferable to perform an anti-soiling treatment using silica powder or the like. Other anti-static treatments such as coating, kneading or deposition may also be performed. In particular, release treatment using a silicone-based, fluorine-based or long-chain alkyl-based release agent makes it easier to peel off the film-like elastic layer.
  • the transparent resin film is not particularly limited, but is preferably transparent and composed of a single layer film.
  • transparent resin films include polyester-based resins such as polyethylene terephthalate and polyethylene naphthalate, acetate-based resins, polyethersulfone-based resins, polycarbonate-based resins, polyamide-based resins, polyimide-based resins, polyolefin-based resins, (meth)acrylic-based resins, polyvinyl chloride-based resins, polyvinylidene chloride-based resins, polystyrene-based resins, polyvinyl alcohol-based resins, polyarylate-based resins, and polyphenylene sulfide-based resins.
  • polyester resins, polyimide resins, and polyethersulfone resins are preferred.
  • the thickness of the transparent resin film is preferably within the range of 2 to 200 ⁇ m, and more preferably within the range of 20 to 188 ⁇ m.
  • the method for applying the UV-curable acrylic adhesive is not particularly limited, and any conventionally known method can be used.
  • application methods include roll coating, kiss roll coating, gravure coating, reverse coating, roll brushing, spray coating, dip roll coating, bar coating, knife coating, air knife coating, curtain coating, lip coating, and die coater methods.
  • the illuminance of the ultraviolet light irradiated to the ultraviolet-curable acrylic adhesive is preferably within the range of 5 to 200 mW/ cm2 .
  • the illuminance of the ultraviolet light is preferably within the range of 5 to 200 mW/ cm2 .
  • the polymerization reaction time can be shortened, resulting in excellent productivity.
  • the rapid consumption of the photopolymerization initiator can be suppressed.
  • the polymerization proceeds sufficiently, and a high molecular weight polymer ((meth)acrylic polymer) can be obtained. This allows for an elastic layer with excellent retention, especially at high temperatures.
  • the integrated amount of ultraviolet light is preferably within the range of 100 to 5000 mJ/ cm2 .
  • the ultraviolet lamp used in the present invention is not particularly limited, but is preferably an LED lamp.
  • the LED lamp emits less heat than other ultraviolet lamps, so that the temperature rise during the ultraviolet curing of the ultraviolet curing acrylic adhesive can be suppressed. This allows a polymer with a high molecular weight to be obtained, and an elastic layer with sufficient cohesive strength can be obtained, thereby increasing the holding power at high temperatures when the adhesive sheet is made.
  • the ultraviolet lamp may be a combination of a plurality of ultraviolet lamps.
  • ultraviolet light may be intermittently irradiated, and a light period during which ultraviolet light is irradiated and a dark period during which ultraviolet light is not irradiated may be provided.
  • the final polymerization rate of the monomer components in the UV-curable acrylic adhesive is preferably 90% or more, more preferably 95% or more, and even more preferably 98% or more.
  • the peak wavelength of the ultraviolet light irradiated onto the ultraviolet-curing acrylic adhesive is preferably within the range of 200 to 500 nm, and more preferably within the range of 300 to 450 nm.
  • the peak wavelength of the ultraviolet light is 500 nm or less, the photopolymerization initiator decomposes and the polymerization reaction begins.
  • the peak wavelength of the ultraviolet light is 200 nm or more, the scission of the polymer chain can be suppressed, and sufficient adhesion can be obtained.
  • Methods for blocking oxygen include creating a release film on the coating layer of the UV-curable acrylic adhesive, and carrying out the polymerization reaction in a nitrogen atmosphere.
  • release films include the release films mentioned above.
  • the storage modulus of the elastic layer at 25° C. is preferably within the range of 0.5 to 10.0 MPa, and more preferably within the range of 1.2 to 8.0 MPa.
  • the loss tangent (tan ⁇ 1 ) at 25° C. of the elastic layer is not particularly limited as long as it satisfies the relationship of formula (1) above, but is preferably within the range of 0.01 to 1.5, and more preferably within the range of 0.1 to 1.5.
  • the storage modulus and loss tangent (tan ⁇ 1 ) at 25° C. of the elastic layer can be adjusted by appropriately selecting the type and content of materials (monomer components, UV absorbers, photopolymerization initiators, etc.), UV irradiation conditions, etc.
  • the storage modulus and loss tangent of the elastic layer at 25° C. can be measured using a viscoelasticity measuring device "ARES-G2" (manufactured by TA Instruments Japan, Inc.) under the following test conditions.
  • Test conditions dynamic viscoelasticity test
  • Testing machine Viscoelasticity measuring device "ARES-G2” (manufactured by TA Instruments Japan, Inc.)
  • Deformation method Rotation Temperature range: -50 to 100°C Frequency: 1Hz
  • Displacement Strain 0.05%
  • Distance between chucks Automatically variable so that the load becomes 10 g (approximately equal to the sample thickness).
  • the thickness of the elastic layer is preferably within the range of 2 to 60 ⁇ m, more preferably within the range of 2 to 20 ⁇ m, and even more preferably within the range of 2 to 15 ⁇ m.
  • the weight average molecular weight (Mw) of the resin material (e.g., (meth)acrylic polymer) used in the elastic layer is preferably within a range of 100,000 to 5,000,000, and more preferably within a range of 200,000 to 1,000,000, from the viewpoint of controlling the loss tangent (tan ⁇ 1 ).
  • the weight average molecular weight (Mw) of the resin material used in the elastic layer is preferably smaller than the weight average molecular weight (Mw) of the resin material used in the optical film described below. This allows the effects of the present invention to be obtained more efficiently.
  • the weight average molecular weight (Mw) of the resin material can be measured using a gel permeation chromatograph "HLC8220GPC” (manufactured by Tosoh Corporation) and columns “TSK-GEL G6000", “HXL-G5000”, “HXL-G5000”, “HXL-G4000”, and “HXL-G3000HXL” (all manufactured by Tosoh Corporation, in series). 20 mg ⁇ 0.5 mg of a sample is dissolved in 10 mL of tetrahydrofuran and filtered through a 0.45 mm filter. 100 mL of this solution is then injected into a column (temperature 40° C.) and measured with an RI detector at a temperature of 40° C., and the value is expressed in terms of styrene.
  • the glass transition temperature (Tg) of the elastic layer is preferably 0°C or lower, more preferably -10°C or lower, and even more preferably -20°C or lower, from the viewpoint of achieving both impact resistance and flexibility in a low-temperature environment.
  • the glass transition temperature (Tg) can be measured in accordance with JIS K 7121 (2012) using a DSC (Differential Scanning Colorimetry) device.
  • optical film according to the present invention is characterized in that it contains rubber particles and that, when the loss tangents of the elastic layer and the optical film according to the present invention are tan ⁇ 1 and tan ⁇ 2 , respectively, the ratio of the loss tangents (tan ⁇ 1 /tan ⁇ 2 ) satisfies the above formula (1).
  • the optical film according to the present invention is not particularly limited as long as it contains rubber particles and has a loss tangent that satisfies the above formula (1).
  • the optical film according to the present invention is preferably in the form of a rollable film, but may also be in the form of a coated layer formed by coating on an adjacent layer.
  • the optical film according to the present invention is preferably prepared by incorporating rubber particles such as a graft copolymer into a resin material and molding the material into a film shape. From the viewpoint of flexibility, it is preferable that the rubber composition contains at least a combination of a thermoplastic (meth)acrylic resin and rubber particles of a graft copolymer.
  • the optical film according to the present invention preferably has an average light transmittance of 90% or less in the wavelength region of 380 to 780 nm (visible light region), more preferably in the range of 39 to 89%.
  • the optical film can be endowed with a part of the function of a polarizing plate, specifically, external light reflection can be sufficiently suppressed.
  • the laminate is used as a cover glass unit of a display device, sufficient brightness can be obtained.
  • the average light transmittance in the visible light region can be adjusted by incorporating a colorant into the optical film.
  • rubber particles refers to particles containing a resin that exhibits rubber elasticity at room temperature.
  • the optical film according to the present invention can be imparted with toughness (flexibility) by containing rubber particles, and the loss tangent (tan ⁇ 2 ) of the optical film can be appropriately adjusted.
  • the layer structure of the rubber particles according to the present invention may be a single layer structure or a multi-layer structure.
  • the resin exhibiting rubber elasticity at room temperature (hereinafter also referred to as "rubber-like polymer”) is not particularly limited.
  • the order of monomer arrangement is also not particularly limited, and may be, for example, linear, comb-like (graft type), or branched (star type).
  • the rubber-like polymer may have a structure that is partially crosslinked with a crosslinkable monomer.
  • the rubber-like polymer is preferably a soft crosslinked polymer having a glass transition temperature (Tg) of 0° C. or lower, from the viewpoint of exhibiting rubber elasticity at room temperature.
  • crosslinked polymers include butadiene-based crosslinked polymers, (meth)acrylic crosslinked polymers, organosiloxane crosslinked polymers, etc.
  • (meth)acrylic crosslinked polymers are preferred, and acrylic crosslinked polymers are more preferred, from the viewpoint of a small difference in refractive index from thermoplastic (meth)acrylic resins and less loss of transparency of the optical film.
  • the rubber particles according to the present invention are preferably particles containing an acrylic crosslinked polymer (hereinafter also referred to as an "acrylic rubber-like polymer").
  • the content of the rubber particles is preferably within a range of 10 to 80% by mass based on the total mass of the optical film, which allows the optical film to have an appropriate hardness and a desired loss tangent (tan ⁇ 2 ).
  • the rubber particles according to the present invention preferably contain an acrylic rubber-like polymer.
  • the acrylic rubber-like polymer will be referred to as "acrylic rubber-like polymer (a)" below.
  • the acrylic rubber-like polymer (a) is a crosslinked polymer having, as a main component, a structural unit derived from an acrylic ester.
  • "having as a main component” means that the content of structural units derived from acrylic ester is within the range described below.
  • the acrylic rubber-like polymer (a) is preferably a crosslinked polymer having structural units derived from an acrylic acid ester, structural units derived from other monomers copolymerizable therewith, and structural units derived from a polyfunctional monomer having two or more radically polymerizable groups (non-conjugated reactive double bonds) in one molecule.
  • the acrylic acid ester is preferably an alkyl acrylate having an alkyl group having 1 to 12 carbon atoms, such as methyl acrylate (methyl acrylate), ethyl acrylate (ethyl acrylate), n-propyl acrylate (n-propyl acrylate), n-butyl acrylate (n-butyl acrylate), sec-butyl acrylate (sec-butyl acrylate), isobutyl acrylate (isobutyl acrylate), benzyl acrylate (benzyl acrylate), cyclohexyl acrylate (cyclohexyl acrylate), 2-ethylhexyl acrylate (2-ethylhexyl acrylate), or n-octyl acrylate (n-octyl acrylate). These may be used alone or in combination of two or more.
  • the content of structural units derived from acrylic esters is preferably within the range of 40 to 90 mass % of all structural units constituting the acrylic rubber-like polymer (a), and more preferably within the range of 50 to 80 mass %. By being within the above range, sufficient toughness can be imparted to the optical film.
  • Examples of other monomers copolymerizable with acrylic acid esters include methacrylic acid esters such as methyl methacrylate, styrenes such as styrene and methylstyrene, (meth)acrylonitriles, (meth)acrylamides, and (meth)acrylic acid.
  • methacrylic acid esters such as methyl methacrylate
  • styrenes such as styrene and methylstyrene
  • (meth)acrylonitriles such as methyl)acrylamides
  • (meth)acrylic acid examples include methacrylic acid esters such as methyl methacrylate, styrenes such as styrene and methylstyrene, (meth)acrylonitriles, (meth)acrylamides, and (meth)acrylic acid.
  • styrenes are preferred. These may be used alone or in combination of two or more.
  • the content of structural units derived from other monomers copolymerizable with acrylic esters is preferably within the range of 5 to 55% by mass, and more preferably within the range of 10 to 45% by mass, based on the total structural units constituting the acrylic rubber-like polymer (a).
  • polyfunctional monomers having two or more radically polymerizable groups in one molecule include allyl (meth)acrylate, triallyl cyanurate, triallyl isocyanurate, diallyl phthalate, diallyl malate, divinyl adipate, divinyl benzene, 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.
  • the content of structural units derived from polyfunctional monomers having two or more radically polymerizable groups in one molecule is preferably within the range of 0.05 to 10% by mass relative to all structural units constituting the acrylic rubber-like polymer (a).
  • the content is more preferably within the range of 0.1 to 5% by mass.
  • composition of the monomers constituting the acrylic rubber-like polymer (a) can be measured, for example, by the peak area ratio detected by pyrolysis GC-MS.
  • the glass transition temperature (Tg) of the acrylic rubber-like polymer (a) is preferably 0°C or lower, and more preferably -10°C or lower. A glass transition temperature of 0°C or lower can impart appropriate toughness to the optical film.
  • the glass transition temperature (Tg) of the acrylic rubber-like polymer (a) can be measured by the same method as described above.
  • the glass transition temperature (Tg) of the acrylic rubber-like polymer (a) can be adjusted by the composition of the acrylic rubber-like polymer (a). For example, in order to lower the glass transition temperature (Tg), it is preferable to adjust the mass ratio of the acrylic ester having an alkyl group with 4 or more carbon atoms to the other monomer copolymerizable with the acrylic ester.
  • the mass ratio is expressed as the mass of the acrylic ester/the mass of the other monomer copolymerizable with the acrylic ester.
  • the mass ratio is preferably 3 or more, and is preferably within the range of 4 to 10.
  • the particles containing the acrylic rubber-like polymer (a) may be particles consisting of only the acrylic rubber-like polymer (a). They may also be particles having a hard layer consisting of a hard crosslinked polymer (c) having a glass transition temperature (Tg) of 20°C or higher, and a soft layer consisting of the acrylic rubber-like polymer (a) arranged around it. In addition, they may be particles consisting of an acrylic graft copolymer obtained by polymerizing a mixture of monomers such as methacrylic acid esters in at least one stage in the presence of the acrylic rubber-like polymer (a). The particles consisting of the acrylic graft copolymer may be core-shell type particles having a core containing the acrylic rubber-like polymer (a) and a shell covering the core.
  • the core contains an acrylic rubber-like polymer (a) and may further contain a hard crosslinked polymer (c) as necessary. That is, the core may have a soft layer made of the acrylic rubber-like polymer (a) and a hard layer made of the hard crosslinked polymer (c) disposed inside the soft layer.
  • the rigid crosslinked polymer will be referred to as "crosslinked polymer (c)" below.
  • the crosslinked polymer (c) is a crosslinked polymer containing a methacrylic acid ester as a main component.
  • the crosslinked polymer (c) is preferably a crosslinked polymer having a structural unit derived from a methacrylic acid ester, a structural unit derived from another monomer copolymerizable therewith, and a structural unit derived from a polyfunctional monomer having two or more radically polymerizable groups in one molecule.
  • the methacrylic acid ester is preferably an alkyl methacrylate ester, such as the above-mentioned alkyl acrylate ester in which the alkyl acid is replaced with methacrylic acid.
  • alkyl methacrylate ester examples include the same monomers as those described above as the other monomers copolymerizable with the acrylic acid ester.
  • polyfunctional monomer having two or more radically polymerizable groups in one molecule include the same as those mentioned above.
  • the content of structural units derived from methacrylic acid alkyl esters is preferably within the range of 40 to 100% by mass relative to all structural units constituting the crosslinked polymer (c).
  • the content of structural units derived from other monomers copolymerizable with methacrylic acid esters is preferably within the range of 60 to 0% by mass relative to all structural units constituting the crosslinked polymer (c).
  • the content of structural units derived from polyfunctional monomers having two or more radically polymerizable groups in one molecule is preferably within the range of 0.01 to 10% by mass relative to all structural units constituting the crosslinked polymer (c).
  • the shell portion preferably contains a methacrylic polymer (b) (another polymer) having as its main component a structural unit derived from a methacrylic acid ester, graft-bonded to the acrylic rubber-like polymer (a).
  • a methacrylic polymer having a structural unit derived from a methacrylic acid ester as a main component will be referred to as a "methacrylic polymer (b)" hereinafter.
  • “having as a main component” means that the content of the structural unit derived from the methacrylic acid ester is within the range described below.
  • the methacrylic acid ester constituting the methacrylic polymer (b) is preferably a methacrylic acid alkyl ester having an alkyl group of 1 to 12 carbon atoms, such as methyl methacrylate. These may be used alone or in combination of two or more.
  • the content of the methacrylic acid ester is preferably 50% by mass or more relative to all structural units constituting the methacrylic polymer (b).
  • the content of the methacrylic acid ester is more preferably 70% by mass or more relative to all structural units constituting the methacrylic polymer (b).
  • the methacrylic polymer (b) may further have a structural unit derived from another monomer copolymerizable with the methacrylic acid ester.
  • the other copolymerizable monomer include acrylic acid esters such as methyl acrylate (methyl acrylate), ethyl acrylate (ethyl acrylate), and n-butyl acrylate (n-butyl acrylate); and (meth)acrylic monomers having an alicyclic, heterocyclic or aromatic ring (ring-containing (meth)acrylic monomers) such as benzyl (meth)acrylate (benzyl (meth)acrylate), dicyclopentanyl (meth)acrylate (dicyclopentanyl (meth)acrylate), and phenoxyethyl (meth)acrylate (phenoxyethyl (meth)acrylate).
  • the content of structural units derived from other copolymerizable monomers is preferably 50% by mass or less, and more preferably 30% by mass or less, based on the total structural units constituting the methacrylic polymer (b).
  • the ratio of the graft component in the rubber particles is preferably within the range of 10 to 250% by mass, and more preferably within the range of 15 to 150% by mass.
  • a graft ratio of 10% by mass or more means that the ratio of the graft component, i.e., the methacrylic polymer (b) whose main component is a structural unit derived from a methacrylic acid ester, is appropriately high. This makes it easier to increase the compatibility between the rubber particles and the methacrylic resin, making the rubber particles even less likely to aggregate. In addition, the rigidity of the film is less likely to be impaired.
  • a graft ratio of 250% by mass or less ensures that the ratio of the acrylic rubber-like polymer (a) is not too low, so that the toughness of the optical film is less likely to be impaired.
  • the brittleness of the optical film can be sufficiently improved.
  • the graft rate can be measured using the following method.
  • Graft ratio (mass %) [ ⁇ (mass of methyl ethyl ketone insoluble matter) ⁇ (mass of acrylic rubber-like polymer (a)) ⁇ /(mass of acrylic rubber-like polymer (a)] ⁇ 100
  • the shape of the rubber particles is not particularly limited, but it is preferable that the shape is close to a perfect sphere.
  • the term "nearly spherical” refers to a shape in which the aspect ratio of the rubber particles is within the range of 1 to 2 when the cross section or surface of the optical film is observed.
  • the laminate is sufficiently resistant to deformation caused by contact with the rolls during transportation and deformation caused by internal stress during winding.
  • the average particle size of the rubber particles is preferably within the range of 100 to 400 nm. Having a particle size of 100 nm or more provides the optical film with sufficient toughness and stress relaxation properties. Furthermore, having a particle size of 400 nm or less ensures that the transparency of the optical film is not easily impaired. From the above viewpoints, it is more preferable that the average particle size of the rubber particles is within the range of 150 to 300 nm.
  • the average particle size of rubber particles can be calculated using the following method.
  • the average particle size of rubber particles can be measured as the average of the circle-equivalent diameters of 100 particles obtained by SEM or TEM photography of the surface or slice of the laminate.
  • the circle-equivalent diameter can be calculated by converting the projected area of the particle obtained by photography into the diameter of a circle with the same area.
  • the rubber particles observed by SEM or TEM observation at a magnification of 5000 times are used to calculate the average particle size.
  • the resin material is not particularly limited, and examples thereof include thermoplastic (meth)acrylic resins and cycloolefin resins.
  • the weight average molecular weight (Mw) of the resin material varies depending on the type of resin material, but is preferably within the range of 5,000 to 4,000,000, for example.
  • the weight average molecular weight (Mw) of the resin material can be measured by the method described above.
  • thermoplastic (meth)acrylic resin preferably has at least a structural unit derived from methyl methacrylate.
  • the thermoplastic (meth)acrylic resin preferably further has a structural unit derived from phenylmaleimide.
  • thermoplastic (meth)acrylic resin further has a structural unit derived from an alkyl acrylate.
  • thermoplastic (meth)acrylic resin has a structural unit derived from methyl methacrylate, a structural unit derived from phenylmaleimide, and a structural unit derived from an alkyl acrylate.
  • the content of structural units derived from methyl methacrylate is preferably within the range of 50 to 95% by mass, and more preferably within the range of 70 to 90% by mass, relative to all structural units constituting the thermoplastic (meth)acrylic resin.
  • the structural units derived from phenylmaleimide have a relatively rigid structure, which can increase the storage modulus of the optical film.
  • the structural units derived from phenylmaleimide have a relatively bulky structure, which can have microvoids in the resin matrix through which the graft copolymer (rubber particles) can move. This makes it easier to concentrate the graft copolymer (rubber particles) in the surface layer of the optical film.
  • the content of structural units derived from phenylmaleimide is preferably within the range of 1 to 25% by mass relative to all structural units constituting the thermoplastic (meth)acrylic resin.
  • the content of structural units derived from phenylmaleimide is 1% by mass or more, the storage modulus of the optical film is easily increased, and when the content is 25% by mass or less, the brittleness of the optical film is less likely to be excessively impaired. From the above viewpoint, it is more preferable that the content of structural units derived from phenylmaleimide is within the range of 7 to 15% by mass.
  • the structural units derived from acrylic acid alkyl esters can impart a suitable degree of flexibility to the resin. Therefore, for example, by combining them with structural units derived from phenylmaleimide, it is possible to improve the brittleness caused by the inclusion of structural units derived from phenylmaleimide.
  • the alkyl acrylate is preferably an alkyl acrylate having 1 to 7 carbon atoms, and more preferably 1 to 5 carbon atoms in the alkyl portion.
  • acrylic acid alkyl esters include methyl acrylate (methyl acrylate), ethyl acrylate (ethyl acrylate), propyl acrylate (propyl acrylate), butyl acrylate (butyl acrylate), 2-hydroxyethyl acrylate (2-hydroxyethyl acrylate), hexyl acrylate (hexyl acrylate), and 2-ethylhexyl acrylate (2-ethylhexyl acrylate).
  • the content of structural units derived from acrylic acid alkyl esters is preferably within the range of 1 to 25% by mass relative to the total structural units constituting the thermoplastic (meth)acrylic resin.
  • the thermoplastic (meth)acrylic resin can be given appropriate flexibility. This can improve the brittleness of the optical film, making it less likely to break.
  • the content of structural units derived from acrylic acid alkyl esters is 25% by mass or less, the decrease in the glass transition temperature (Tg) of the thermoplastic (meth)acrylic resin can be suppressed, and sufficient heat resistance and storage modulus of the optical film can be obtained.
  • the content of structural units derived from acrylic acid alkyl esters is more preferably within the range of 5 to 15% by mass.
  • the ratio of the structural units derived from phenylmaleimide to the total amount of the structural units derived from phenylmaleimide and the structural units derived from acrylic acid alkyl ester is preferably within the range of 20 to 70% by mass. When this ratio is 20% by mass or more, it is easy to increase the storage modulus of the optical film, and when it is 70% by mass or less, it is possible to improve the brittleness of the optical film.
  • the glass transition temperature (Tg) of the thermoplastic (meth)acrylic resin is preferably 100°C or higher, and more preferably within the range of 120 to 150°C. By keeping it within the above range, the heat resistance of the optical film can be improved.
  • Tg the thermoplastic (meth)acrylic resin
  • the weight-average molecular weight (Mw) of the thermoplastic (meth)acrylic resin is preferably 100,000 or more, and more preferably 1,000,000 or more.
  • the toughness of the optical film can be increased. This makes it possible to prevent the optical film from breaking due to the transport tension during transport of the film.
  • the storage modulus of the optical film can be increased, winding deformation can be suppressed.
  • the weight average molecular weight (Mw) of the thermoplastic (meth)acrylic resin is more preferably within the range of 1.5 million to 3 million.
  • the weight average molecular weight (Mw) of the thermoplastic (meth)acrylic resin can be measured by the method described above.
  • the content of the thermoplastic (meth)acrylic resin is preferably within the range of 5 to 95% by mass relative to the total mass of the optical film. It is more preferably within the range of 10 to 60% by mass, even more preferably within the range of 10 to 50% by mass, and particularly preferably within the range of 10 to 40% by mass.
  • the content of the rubber particles is preferably within the range of 10 to 80% by mass relative to the total mass of the optical film. Also, it is more preferable that the content is within the range of 20 to 60% by mass, and even more preferable that the content is within the range of 20 to 50% by mass. By being within the above range, the size of the aggregates becomes sufficient and approximately uniform, foreign matter is less likely to be mixed into the film, and an optical film with improved optical properties and mechanical properties is obtained.
  • the cycloolefin resin is preferably a polymer of a cycloolefin monomer, or a copolymer of a cycloolefin monomer and another monomer copolymerizable with the cycloolefin monomer.
  • the cycloolefin monomer is preferably a cycloolefin monomer having a norbornene skeleton. Among them, a cycloolefin monomer having a structure represented by the following general formula (A-1) or (A-2) is more preferable.
  • R 1 to R 4 each independently represent a hydrogen atom, a hydrocarbon group having 1 to 30 carbon atoms, or a polar group.
  • p represents an integer of 0 to 2.
  • R 1 to R 4 do not all represent hydrogen atoms at the same time, R 1 and R 2 do not both represent hydrogen atoms, and R 3 and R 4 do not both represent hydrogen atoms.
  • the hydrocarbon group having 1 to 30 carbon atoms represented by R 1 to R 4 is, for example, preferably a hydrocarbon group having 1 to 10 carbon atoms, and more preferably a hydrocarbon group having 1 to 5 carbon atoms.
  • the hydrocarbon group having 1 to 30 carbon atoms may further have a linking group containing, for example, a halogen atom, an oxygen atom, a nitrogen atom, a sulfur atom, or a silicon atom.
  • linking groups include divalent polar groups such as a carbonyl group, an imino group, an ether bond, a silyl ether bond, and a thioether bond.
  • Examples of the hydrocarbon group having 1 to 30 carbon atoms include a methyl group, an ethyl group, a propyl group, and a butyl group.
  • examples of the polar group represented by R 1 to R 4 include a carboxy group, a hydroxy group, an alkoxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, an amino group, an amide group, and a cyano group.
  • a carboxy group, a hydroxy group, an alkoxycarbonyl group, or an aryloxycarbonyl group is preferable. From the viewpoint of solubility during solution casting, an alkoxycarbonyl group or an aryloxycarbonyl group is preferable.
  • p is preferably 1 or 2 from the viewpoint of increasing heat resistance.
  • p is 1 or 2 from the viewpoint of increasing heat resistance.
  • the resulting polymer becomes bulky and the glass transition temperature is likely to be improved.
  • it becomes somewhat responsive to humidity, making it easier to control the curl balance when formed into a laminate.
  • R5 represents a hydrogen atom, a hydrocarbon group having 1 to 5 carbon atoms, or an alkylsilyl group having an alkyl group having 1 to 5 carbon atoms.
  • R6 represents a carboxy group, a hydroxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, an amino group, an amido group, a cyano group, or a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom).
  • p represents an integer of 0 to 2.
  • R 5 in the above general formula (A-2) is preferably a hydrocarbon group having 1 to 5 carbon atoms, and more preferably a hydrocarbon group having 1 to 3 carbon atoms.
  • R6 is preferably a carboxy group, a hydroxy group, an alkoxycarbonyl group, or an aryloxycarbonyl group, and more preferably an alkoxycarbonyl group or an aryloxycarbonyl group from the viewpoint of solubility during solution casting.
  • p in the above general formula (A-2) is preferably 1 or 2.
  • p is 1 or 2
  • the resulting polymer becomes bulky and the glass transition temperature is easily improved.
  • the cycloolefin monomer is preferably a cycloolefin monomer having the structure represented by the above general formula (A-2).
  • the crystallinity of an organic compound is reduced by breaking the symmetry, and the solubility in an organic solvent is improved.
  • R 5 and R 6 in general formula (A-2) are substituted on only one side of the carbon atoms constituting the ring with respect to the symmetric axis of the molecule, and therefore the symmetry of the molecule is low. That is, the cycloolefin monomer having the structure represented by general formula (A-2) is highly soluble and is therefore suitable for producing an optical film by a solution casting method.
  • the content of the cycloolefin monomer having the structure represented by general formula (A-2) in the cycloolefin resin is preferably 70 mol% or more relative to the total number of moles of all cycloolefin monomers constituting the cycloolefin resin. Also, it is more preferable that it is 80 mol% or more, and even more preferable that it is 100 mol%.
  • the content of the cycloolefin monomer having the structure represented by general formula (A-2) is 70 mol% or more, the orientation of the cycloolefin resin is increased, and the phase difference (retardation) value is likely to increase.
  • cycloolefin monomers having a structure represented by general formula (A-1) are shown as example compounds 1 to 14.
  • specific examples of cycloolefin monomers having a structure represented by general formula (A-2) are shown as example compounds 15 to 34.
  • copolymerizable monomers capable of ring-opening copolymerization include cycloolefins such as cyclobutene, cyclopentene, cycloheptene, cyclooctene, and dicyclopentadiene.
  • Examples of copolymerizable monomers capable of addition copolymerization include unsaturated double bond-containing compounds, vinyl cyclic hydrocarbon monomers, (meth)acrylates, etc.
  • Examples of unsaturated double bond-containing compounds include olefin compounds having 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.
  • (meth)acrylates examples include alkyl (meth)acrylates having 1 to 20 carbon atoms, such as methyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and cyclohexyl (meth)acrylate.
  • the content of the cycloolefin monomer in a copolymer of a cycloolefin monomer and a copolymerizable monomer is preferably within the range of 20 to 80 mol %, and more preferably within the range of 30 to 70 mol %, based on the total of all monomers constituting the copolymer.
  • the cycloolefin resin is a polymer obtained by homopolymerizing or copolymerizing a cycloolefin monomer having a norbornene skeleton, preferably a cycloolefin monomer having a structure represented by the above general formula (A-1) or (A-2).
  • Examples of such polymers include the following.
  • Ring-opening polymer of cycloolefin monomer 1) Ring-opening polymer of cycloolefin monomer; 2) Ring-opening copolymer of cycloolefin monomer and a copolymerizable monomer capable of ring-opening copolymerization therewith; 3) Hydrogenated product of ring-opening (co)polymer of 1) or 2) above; 4) (co)polymer obtained by cyclizing ring-opening (co)polymer of 1) or 2) above by Friedel-Crafts reaction and then hydrogenating it; 5) Saturated copolymer of cycloolefin monomer and unsaturated double bond-containing compound; 6) Addition copolymer of cycloolefin monomer and vinyl cyclic hydrocarbon monomer and hydrogenated product thereof; 7) Alternating copolymer of cycloolefin monomer and (meth)acrylate.
  • the polymers 1) to 7) above can all be obtained by known methods, for example, the methods described in JP-A-2008-107534 and JP-A-2005-227606.
  • the catalyst and solvent used in the ring-opening copolymerization 2) above can be, for example, those described in paragraphs 0019 to 0024 of JP-A-2008-107534.
  • the catalyst used in the hydrogenation 3) and 6) above can be, for example, those described in paragraphs 0025 to 0028 of JP-A-2008-107534.
  • the acidic compound used in the Friedel-Crafts reaction 4) above can be, for example, those described in paragraph 0029 of JP-A-2008-107534.
  • the catalyst used in the addition polymerization 5) to 7) above can be, for example, those described in paragraphs 0058 to 0063 of JP-A-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 JP 2005-227606 A.
  • the cycloolefin resin preferably contains at least one of a structural unit represented by the following general formula (B-1) and a structural unit represented by the following general formula (B-2). It is more preferred that the cycloolefin resin contains only a structural unit represented by general formula (B-2), or contains both a structural unit represented by general formula (B-1) and a structural unit represented by general formula (B-2).
  • the structural unit represented by general formula (B-1) is a structural unit derived from the cycloolefin monomer represented by the aforementioned general formula (A-1), and the structural unit represented by general formula (B-2) is a structural unit derived from the cycloolefin monomer represented by the aforementioned general formula (A-2).
  • R 1 to R 4 and p have the same meanings as R 1 to R 4 and p in the above general formula (A-1), respectively.
  • R 5 to R 6 and p have the same meanings as R 5 to R 6 and p in general formula (A-2), respectively.
  • the cycloolefin resin used in the present invention may be a commercially available product.
  • examples of commercially available cycloolefin resins include ARTON (registered trademark, hereinafter the same) G (e.g., G7810, etc.), ARTON F, ARTON R (e.g., R4500, R4900, R5000, etc.), and ARTON RX (e.g., RX4500, etc.), all manufactured by JSR Corporation.
  • the intrinsic viscosity [ ⁇ ]inh of the cycloolefin resin at 30° C. is preferably within the range of 0.2 to 5 cm 3 /g, more preferably within the range of 0.3 to 3 cm 3 /g, and even more preferably within the range of 0.4 to 1.5 cm 3 /g.
  • the number average molecular weight (Mn) of the cycloolefin resin is preferably within the range of 8,000 to 100,000, more preferably within the range of 10,000 to 80,000, and even more preferably within the range of 12,000 to 50,000.
  • the weight average molecular weight (Mw) of the cycloolefin resin is preferably within the range of 20,000 to 300,000, more preferably within the range of 30,000 to 250,000, and even more preferably within the range of 40,000 to 200,000.
  • the cycloolefin resin has good heat resistance, water resistance, chemical resistance, mechanical properties, and moldability as a base film.
  • the glass transition temperature (Tg) of cycloolefin resin is usually 110°C or higher, preferably in the range of 110 to 350°C, more preferably in the range of 120 to 250°C, and even more preferably in the range of 120 to 220°C. Having a Tg of 110°C or higher makes it possible to suppress deformation under high temperature conditions. On the other hand, having a Tg of 350°C or lower makes molding easier and suppresses deterioration of the resin due to heat during molding processing.
  • the content of the cycloolefin resin is preferably 70% by mass or more, and more preferably 80% by mass or more, based on the total mass of the optical film.
  • the optical film contains a cycloolefin resin, it is preferable that the optical film further contains fine particles.
  • inorganic compound particles include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, and calcium phosphate.
  • examples of fine particles of organic compounds include polytetrafluoroethylene, cellulose acetate, polystyrene, polymethyl methacrylate, polypropyl methacrylate, polymethyl acrylate, polyethylene carbonate, acrylic styrene resins, silicone resins, polycarbonate resins, benzoguanamine resins, melamine resins, polyolefin powders, polyester resins, polyamide resins, polyimide resins, polyethylene fluoride resins, pulverized fractions of organic polymer compounds such as starch, and polymer compounds synthesized by suspension polymerization.
  • the fine particles preferably contain silicon, and more preferably silicon dioxide, from the viewpoint of reducing turbidity.
  • Commercially available products of such fine particles include, for example, Aerosil (registered trademark, the same applies below) R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, and TT600 (all manufactured by Nippon Aerosil Co., Ltd.).
  • the optical film according to the present invention can adjust the average light transmittance in the visible light region by containing a colorant.
  • the colorant may be used alone or in combination of two or more kinds. From the viewpoint of the balance between brightness and color gamut, the content of the colorant is preferably within the range of 0.05 to 2.0% by mass based on the total mass of the resin for optical films.
  • At least one of them has a maximum absorption wavelength in the wavelength region of 570 to 610 nm. This makes it possible to reduce the average light transmittance of the optical film in the wavelength region of 570 to 610 nm, and to prevent the color gamut of the display device from narrowing.
  • the absorption maximum wavelength in the wavelength region of 570 to 610 nm is the maximum absorption maximum wavelength of the colorant.
  • maximum absorption maximum wavelength refers to the absorption maximum wavelength when there is only one absorption maximum wavelength, and refers to the absorption maximum wavelength that shows the maximum absorbance when there are multiple absorption maximum wavelengths.
  • the content of the colorant having a maximum absorption wavelength in the wavelength region of 570 to 610 nm is preferably within the range of 0.02 to 0.6 mass % relative to the total mass of the resin for optical films.
  • the content is more preferably within the range of 0.05 to 0.3 mass %.
  • the absorption maximum wavelength in the wavelength region of 420 to 460 nm is the longest absorption maximum wavelength of the colorant.
  • the content of the colorant having a maximum absorption wavelength in the wavelength region of 420 to 460 nm is preferably within the range of 0.005 to 0.3 mass % relative to the total mass of the resin for optical films.
  • the content is more preferably within the range of 0.01 to 0.3 mass %.
  • the above absorption maximum wavelength can be determined by dispersing the colorant in dichloromethane and measuring the absorption spectrum using an ultraviolet-visible spectrophotometer (e.g., "UV-2450" (manufactured by Shimadzu Corporation)).
  • an ultraviolet-visible spectrophotometer e.g., "UV-2450” (manufactured by Shimadzu Corporation)
  • the colorant is not particularly limited, and examples thereof include dyes and pigments.
  • the pigment is not particularly limited, and examples thereof include organic pigments, inorganic pigments, minerals, etc., having the following numbers as described in the Color Index.
  • Black pigments are not particularly limited, and examples thereof include carbon black, magnetic materials, iron-titanium composite oxide black, etc.
  • Carbon black is not particularly limited, and examples thereof include channel black, furnace black, acetylene black, thermal black, lamp black, etc.
  • Magnetic materials are not particularly limited, and examples thereof include ferrite, magnetite, etc.
  • the red or magenta pigment is not particularly limited, and examples thereof include C.I. Pigment Red 3, 5, 19, 22, 31, 38, 43, 48:1, 48:2, 48:3, 48:4, 48:5, 49:1, 53:1, 57:1, 57:2, 58:4, 63:1, 81, 81:1, 81:2, 81:3, 81:4, 88, 104, 108, 112, 122, 123, 144, 146, 149, 166, 168, 1 69, 170, 177, 178, 179, 184, 185, 208, 216, 226, 257, Pigment Violet 3, 19, 23, 29, 30, 37, 50, 88, Pigment Orange 13, 16, 20, 36, Ruby (chromium-containing corundum), Garnet, Spinel, etc.
  • the blue or cyan pigment is not particularly limited, and examples thereof include C.I. Pigment Blue 1, 15, 15:1, 15:2, 15:3, 15:4, 15:6, 16, 17-1, 22, 27, 28, 29, 36, 60, and Blue Sapphire (iron- and titanium-containing corundum).
  • the green pigment is not particularly limited, and examples thereof include C.I. Pigment Green 7, 26, 36, 50, and the like.
  • the yellow pigment is not particularly limited, and examples thereof include C.I. Pigment Yellow 1, 3, 12, 13, 14, 17, 34, 35, 37, 55, 74, 81, 83, 93, 94, 95, 97, 108, 109, 110, 137, 138, 139, 153, 154, 155, 157, 166, 167, 168, 180, 185, 193, and yellow sapphire (nickel-containing corundum).
  • the dye is not particularly limited, and may be any dye known in the art, such as those described in paragraphs "0057” to “0060” of WO 2015/111351.
  • the average secondary particle diameter of the pigment is not particularly limited, but is preferably 0.1 ⁇ m or more, and more preferably 0.2 ⁇ m or more. By being within the above range, the sliding properties of the pigment particles are improved and they are less likely to aggregate, thereby further reducing unevenness in the light transmittance of the optical film in the visible light region.
  • the average secondary particle diameter of the pigment is not particularly limited, but is preferably 3 ⁇ m or less, and more preferably 2.6 ⁇ m or less. By being within the above range, dispersion spots in the optical film are less likely to occur, unevenness in the light transmittance of the optical film in the visible light region is further reduced, and the haze value is also reduced.
  • the average secondary particle diameter of a pigment can be determined by directly measuring the size of the secondary particles from an electron microscope photograph of an optical film. Specifically, a transmission electron microscope (TEM) "H-7650" (Hitachi High-Tech Corporation) is used to measure particle images, and the average equivalent diameter of a circle with an equal area of 100 randomly selected secondary particles is calculated, and this value is taken as the average secondary particle diameter.
  • TEM transmission electron microscope
  • the colorant may be a commercially available product or a synthetic product.
  • commercially available products include, but are not limited to, “#950” (manufactured by Mitsubishi Chemical Corporation), “FDR series”, “FDG series”, and “FDB series” (all manufactured by Yamada Chemical Industry Co., Ltd.).
  • Other examples include “Kayaset Black A-N” (manufactured by Nippon Kayaku Co., Ltd.), “NUBIAN (registered trademark) BLACK PC-5857” (manufactured by Orient Chemical Industry Co., Ltd.), and “Plast Black 8950-N” (manufactured by Arimoto Chemical Industry Co., Ltd.).
  • the method for producing the optical film is not particularly limited, but is preferably a method in which a dope containing a resin, rubber particles, a solvent, and any other components is prepared, the dope is applied to a substrate, and then dried.
  • the solvent used for the dope is not particularly limited as long as it can disperse resin and rubber particles well.
  • the solvent 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; ethers such as tetrahydrofuran (THF) and 1,4-dioxane; glycol ethers; and hydrocarbons such as toluene, benzene, cyclohexane, and n-hexane.
  • alcohols such as methanol, ethanol, propanol, n
  • glycol ethers examples include propylene glycol mono (C1-C4) alkyl ethers and propylene glycol mono (C1-C4) alkyl ether esters.
  • propylene glycol mono(C1-C4) alkyl ethers include propylene glycol monomethyl ether (PGME), propylene glycol monoethyl ether, propylene glycol mono-n-propyl ether, propylene glycol monoisopropyl ether, and propylene glycol monobutyl ether.
  • propylene glycol mono (C1-C4) alkyl ether esters include propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, and the like. These may be used alone or in combination of two or more.
  • methyl ethyl ketone, ethyl acetate, acetone, or tetrahydrofuran is preferred from the viewpoints of ease of dissolving the resin material, low boiling point, and ease of increasing the drying speed and productivity.
  • solvents may be further mixed with a solvent such as dichloromethane.
  • the solids concentration of the dope is preferably within the range of, for example, 5 to 20% by mass in order to make it easier to adjust the viscosity.
  • the dope may further contain other components other than those described above, if necessary.
  • the other components include a matting agent (fine particles), an ultraviolet absorbing agent, a surfactant, etc.
  • matting agent can impart slipperiness to the film.
  • matting agents include inorganic fine particles such as silica particles, and organic fine particles with a glass transition temperature of 80°C or higher.
  • ultraviolet absorbers examples include benzotriazole-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, and triazine-based ultraviolet absorbers.
  • Surfactants include, for example, anionic surfactants such as carboxylic acid type, sulfonic acid type, sulfate ester type, and phosphate ester type.
  • Surfactants include cationic surfactants such as alkylamine salt type and quaternary ammonium salt type.
  • Surfactants include amphoteric surfactants such as carboxybetaine type, 2-alkylimidazoline derivative type, glycine type, and amine oxide type. Any type can be used.
  • the order in which the components contained in the dope are mixed is not particularly limited.
  • the method for mixing the components is also not particularly limited, and they may be mixed using, for example, a stirrer.
  • the mixing time is not particularly limited, but is preferably within the range of 1 to 10 hours.
  • the mixing temperature is also not particularly limited, but is preferably within the range of 20 to 50°C.
  • the viscosity of the dope at 25°C is not particularly limited as long as it is sufficient to produce an optical film of the desired thickness, but it is preferably within the range of 5 to 5000 mPa ⁇ s.
  • the viscosity of the dope is 5 mPa ⁇ s or more, it is easy to produce an optical film of the desired thickness.
  • the viscosity is 5000 mPa ⁇ s or less, it is possible to suppress unevenness in thickness caused by an increase in the viscosity of the solution. From the same viewpoint, it is more preferable that the viscosity of the dope is within the range of 100 to 1000 mPa ⁇ s.
  • the viscosity of the dope at 25°C can be measured with an E-type viscometer.
  • the obtained dope may be filtered if necessary.
  • the optical film according to the present invention can be prepared by applying the obtained dope to the surface of a substrate, and then drying the dope to remove the solvent from the dope. At this time, a laminated film including the substrate and the optical film is prepared.
  • the step of applying the dope to the substrate and the step of forming the optical film (drying step) will be described below.
  • Step of applying dope the dope obtained above is applied to the surface of the substrate. Specifically, the dope is coated on the surface of the substrate.
  • the substrate is not particularly limited as long as it can support the optical film, but it is usually preferable for it to be a resin film.
  • polyester resin films examples include polyester resin films (e.g., polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polybutylene naphthalate (PBN), etc.), cycloolefin resin films (COP), acrylic films, and cellulose resin films (e.g., cellulose triacetate film (TAC)).
  • PET resin films e.g., polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polybutylene naphthalate (PBN), etc.
  • COP cycloolefin resin films
  • acrylic films e.g., cellulose triacetate film (TAC)
  • TAC cellulose triacetate film
  • the resin film may be one that has been heat-relaxed or stretched.
  • the heat-relaxing temperature is not particularly limited, but is preferably within the range of (Tg+60) to (Tg+180)°C, where Tg is the glass transition temperature of the resin that constitutes the resin film. Heat-relaxing may be performed before or after the release layer is produced.
  • the stretching treatment can increase the orientation of the resin molecules by stretching the resin film, and can increase the tensile modulus of the resin film.
  • the stretching treatment may be performed, for example, in the uniaxial direction of the resin film or in the biaxial direction.
  • the stretching treatment can be performed under any conditions, and is preferably performed, for example, in a range of a stretch ratio of 120 to 900%.
  • the stretch ratio here is a value obtained by multiplying the stretch ratios in each direction. Whether or not a resin film is stretched (whether or not it is a stretched film) can be confirmed, for example, by whether or not it has an in-plane slow axis (an axis extending in the direction in which the refractive index is maximum).
  • the substrate preferably further has a release layer on the surface of the resin film.
  • the presence of the release layer makes it easier to peel the optical film from the substrate.
  • the release layer is not particularly limited as long as it contains a known release agent or a release agent.
  • the release agent contained in the release layer may be a silicone-based release agent or a non-silicone-based release agent.
  • silicone-based release agent examples include known silicone-based resins.
  • non-silicone release agents include long-chain alkyl pendant polymers obtained by reacting polyvinyl alcohol or ethylene-vinyl alcohol copolymers with long-chain alkyl isocyanates, olefin resins (e.g., copolymerized polyethylene, cyclic polyolefins, polymethylpentene, etc.), polyarylate resins (e.g., polycondensates of aromatic dicarboxylic acid components and dihydric phenol components, etc.), and fluororesins (e.g., polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), copolymers of tetrafluoroethylene and perfluoroalkoxyethylene (PFA), copolymers of tetrafluoroethylene and hexafluoropropylene (FEP), copolymers of te
  • the release layer may further contain additives as necessary.
  • additives include fillers, lubricants (waxes, fatty acid esters, fatty acid amides, etc.), stabilizers (antioxidants, heat stabilizers, light stabilizers, etc.), flame retardants, viscosity adjusters, thickeners, defoamers, ultraviolet absorbers, etc.
  • the thickness of the release layer is not particularly limited as long as it provides the desired releasability, but it is preferably within the range of 0.1 to 1.0 ⁇ m.
  • the thickness of the substrate is not particularly limited, but is preferably within the range of 10 to 100 ⁇ m, and more preferably within the range of 25 to 50 ⁇ m.
  • the method for applying the dope is not particularly limited, and examples thereof include known methods such as back coating, gravure coating, spin coating, wire bar coating, and roll coating. Among these, the back coating method is preferred from the viewpoint of forming a coating film that is thin and has a uniform thickness.
  • the dope applied to the substrate is dried. Drying methods include, for example, blowing air or heating. Among these, drying by blowing air is preferred from the viewpoint of easily suppressing curling of the laminated film.
  • the drying conditions e.g., drying temperature, solvent concentration in the atmosphere, drying time, etc.
  • the amount of residual solvent in the coating film after drying i.e., the optical film
  • the distribution state of the rubber particles in the optical film can be adjusted by adjusting the drying conditions. Specifically, from the viewpoint of making it easier to unevenly distribute the rubber particles, it is preferable to use a solvent that has good affinity with the rubber particles, to set the drying temperature high, and to set the solvent concentration in the atmosphere low.
  • the drying temperature is preferably within the range of (Tb-50) to (Tb+50)°C, and more preferably within the range of (Tb-40) to (Tb+40)°C, where Tb is the boiling point of the solvent (°C).
  • Tb is the boiling point of the solvent (°C).
  • the drying temperature is preferably 40°C or higher.
  • the solvent concentration in the atmosphere during drying is preferably in the range of 0.10 to 0.30 mass%, and more preferably 0.10 to 0.20 mass%. By making it 0.10 mass% or more, excessive evaporation of the solvent can be prevented, making it less likely for cracks to occur in the coating film. Furthermore, by making it 0.30 mass% or less, the evaporation rate of the solvent from the coating film can be increased appropriately, making it easier for the rubber particles to be unevenly distributed on 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 with an infrared gas concentration meter.
  • the optical film according to the present invention is obtained by peeling off the substrate from the laminate film of the substrate and optical film thus obtained.
  • the storage modulus of the optical film at 25°C is preferably within the range of 0.1 to 3.5 GPa, and more preferably within the range of 1.0 to 3.5 GPa, from the viewpoints of impact resistance and flexibility.
  • the loss tangent (tan ⁇ 2 ) of the optical film at 25° C. is not particularly limited as long as it satisfies the relationship of formula (1) above, but is preferably in the range of 0.01 to 0.3, and more preferably in the range of 0.05 to 0.3.
  • the storage modulus and loss tangent (tan ⁇ 2 ) at 25° C. of the optical film can be adjusted by appropriately selecting the type, content, etc. of the material (resin, rubber particles, etc.).
  • the storage modulus and loss tangent at 25° C. of the optical film can be measured using a rheometer device “RSA-3” (manufactured by TA Instruments Japan, Inc.) under the following test conditions.
  • Test conditions dynamic viscoelasticity test
  • Testing machine Dynamic viscoelasticity measuring device "RSA-3” (manufactured by TA Instruments Japan Co., Ltd.)
  • Deformation method tension Preload load: 55g Temperature range: -70 to 200°C Frequency: 1.0Hz Displacement: ⁇ 0.1% Sample: Width 5mm Chuck distance: 20 mm
  • the optical film preferably has an in-plane retardation (R 0 ) represented by the following formula in the range of ⁇ 10 to 10 nm.
  • R 0 (Nx - Ny) x d
  • Nx is the maximum refractive index in the plane of the optical film
  • Ny is the minimum refractive index in the plane of the optical film
  • d is the thickness of the optical film.
  • the in-plane retardation (R 0 ) can be measured using an automatic birefringence meter, for example, an automatic birefringence meter "KOBRA (registered trademark)-21ADH” (manufactured by Oji Scientific Instruments Co., Ltd.) at a wavelength of 590 nm in an environment of a temperature of 23° C. and a humidity of 55% RH.
  • an automatic birefringence meter "KOBRA (registered trademark)-21ADH” (manufactured by Oji Scientific Instruments Co., Ltd.) at a wavelength of 590 nm in an environment of a temperature of 23° C. and a humidity of 55% RH.
  • the thickness of the optical film is preferably within the range of 10 to 60 ⁇ m, more preferably within the range of 15 to 50 ⁇ m, and even more preferably within the range of 20 to 40 ⁇ m.
  • the glass transition temperature of the optical film is preferably within the range of -30 to 180°C. If multiple glass transition temperatures are observed when measuring the glass transition temperature of the optical film, the lowest glass transition temperature observed shall be regarded as the glass transition temperature of the optical film.
  • the glass transition temperature can be measured by the method described above.
  • the manufacturing method of the laminate of the present invention is not particularly limited, and examples thereof include a method in which a glass layer (thin glass layer), an elastic layer (ultraviolet-curable acrylic adhesive), and an optical film are sequentially arranged.
  • the laminate of the present invention is characterized in that, when the loss tangents at 25° C. of the elastic layer and the optical film are tan ⁇ 1 and tan ⁇ 2 , respectively, the ratio of the loss tangents (tan ⁇ 1 /tan ⁇ 2 ) satisfies the following formula (1): Formula (1): 1.0 ⁇ tan ⁇ 1 /tan ⁇ 2 ⁇ 3.0
  • the loss tangent at 25° C. of the elastic layer and the optical film can be measured by the method described above.
  • the elastic layer according to the present invention is preferably made of an adhesive and has a relatively high stress relaxation property.
  • the optical film according to the present invention satisfies the above formula (1). In other words, it is believed that the effects of the present invention can be obtained by using an optical film that has a certain degree of stress relaxation property.
  • the thickness of the laminate of the present invention is preferably within the range of 30 to 110 ⁇ m, and more preferably within the range of 55 to 95 ⁇ m, from the viewpoint of achieving both impact resistance and flexibility.
  • the display device of the present invention is characterized by including the laminate described above. That is, it is possible to provide a display device having a light-emitting device and the laminate described above.
  • the glass layer is preferably disposed on the outer side of the display device than the optical film, that is, the glass layer in the laminate is preferably disposed on the most visible side.
  • the light-emitting device is not particularly limited, but examples include plasma display devices and electroluminescence light-emitting devices.
  • Glass-transition temperature The glass transition temperature (Tg) of each layer was measured using a DSC (Differential Scanning Calorimetry) in accordance with JIS K 7121 (2012).
  • the weight average molecular weight (Mw) of the resin contained in each layer was measured using a gel permeation chromatograph "HLC8220GPC” (manufactured by Tosoh Corporation) and columns “TSK-GEL G6000", “HXL-G5000”, “HXL-G5000”, “HXL-G4000”, and “HXL-G3000HXL” (all manufactured by Tosoh Corporation, in series).
  • 20 mg ⁇ 0.5 mg of a sample was dissolved in 10 mL of tetrahydrofuran and filtered through a 0.45 mm filter. 100 mL of this solution was injected into a column (temperature 40°C) and measured with an RI detector at a temperature of 40°C, and the value was converted into a styrene equivalent value.
  • Step 1 A thin film glass was prepared so that a first surface of the thin film glass was in contact with a carrier substrate having a bonding surface. Then, a contact film having adhesive force was attached to a second surface of the thin film glass opposite to the first surface. (Step 2) The thin glass was then peeled off from the carrier substrate by the highly adhesive contact film. (Step 3) The contact film was removed from the second surface of the thin glass peeled off from the carrier substrate by a weakening treatment (electromagnetic radiation exposure) that weakened the adhesive strength of the contact film.
  • a weakening treatment electromagagnetic radiation exposure
  • step 1 a thin glass film was prepared so as to be in contact with a carrier substrate having a thickness of 500 ⁇ m and to have a predetermined thickness, and then a contact film was attached to the thin glass film.
  • step 2 the thin glass film together with the contact film was peeled off from the carrier substrate in 30 seconds.
  • the contact film used was a commercially available product, "NDS4150-20.”
  • NDS4150-20 is a 150 ⁇ m thick film containing polyolefin (PO), and further has a 10 ⁇ m thick adhesive layer.
  • step 3 the exposed contact film was subjected to a weakening treatment to reduce the adhesive strength.
  • a weakening treatment ultraviolet light with a wavelength of 365 nm was irradiated onto the contact film for 10 seconds.
  • the illuminance of the ultraviolet light was 500 mW/ cm2
  • the cumulative amount of light was 500 mJ/ cm2 .
  • the adhesive strength before the weakening treatment was 11 N/25 mm, but after the weakening treatment, the adhesive strength was reduced to 0.4 N/25 mm. This allowed the contact film to be easily peeled off from the thin film glass, and a thin film glass 1 with a thickness of 30 ⁇ m was obtained.
  • the Tg of the elastic layer 1 was ⁇ 20° C.
  • the storage modulus at 25° C. was 8.00 and the loss tangent (tan ⁇ 1 ) was 0.20.
  • a sample of the elastic layer was prepared by forming an elastic layer on the surface of a release film instead of the optical film 1 in the same manner, and then peeling off the release film. The glass transition temperature, storage modulus, and loss tangent were then measured.
  • a transparent release film was attached to the surface of the ink that was temporarily cured by this irradiation, and further irradiated with ultraviolet rays having a wavelength of 395 nm at an intensity of 200 mW/cm 2 and an accumulated light amount of 1000 mJ/cm 2.
  • the ink was fully cured and the release film was peeled off to produce an elastic layer 2 on the optical film 1.
  • the storage modulus at 25° C. was 1.20, and the loss tangent (tan ⁇ 1 ) was 0.30.
  • Elastic layer 3 was prepared in the same manner as elastic layer 1, except that the ultraviolet ray irradiation conditions were changed.
  • the storage modulus at 25° C. was 10.00, and the loss tangent (tan ⁇ 1 ) was 0.15.
  • Elastic layer 4 was prepared in the same manner as elastic layer 1, except that the ultraviolet ray irradiation conditions were changed.
  • the storage modulus at 25° C. was 0.50, and the loss tangent (tan ⁇ 1 ) was 0.30.
  • Elastic layer 5 was prepared in the same manner as in the preparation of elastic layer 1, except that the ultraviolet ray irradiation conditions were changed.
  • the storage modulus at 25° C. was 1.20, and the loss tangent (tan ⁇ 1 ) was 0.10.
  • Elastic layer 7 was prepared in the same manner as in preparation of elastic layer 1, except that the thickness was changed to 15 ⁇ m.
  • the storage modulus at 25° C. was 8.00, and the loss tangent (tan ⁇ 1 ) was 0.20.
  • Elastic layer 8 was prepared in the same manner as in preparation of elastic layer 1, except that the thickness was changed to 1 ⁇ m.
  • the storage modulus at 25° C. was 8.00, and the loss tangent (tan ⁇ 1 ) was 0.20.
  • Elastic layer 9 was prepared in the same manner as in preparation of elastic layer 1, except that the thickness was changed to 20 ⁇ m.
  • the storage modulus at 25° C. was 8.00, and the loss tangent (tan ⁇ 1 ) was 0.20.
  • Elastic layer 101 was prepared in the same manner as in preparation of elastic layer 1, except that the thickness was changed to 25 ⁇ m.
  • the storage modulus at 25° C. was 0.05, and the loss tangent (tan ⁇ 1 ) was 0.30.
  • the elastic layer 102 was prepared in the same manner as in the preparation of the elastic layer 1, except that the ultraviolet ray irradiation conditions were changed.
  • the storage modulus at 25° C. was 8.00, and the loss tangent (tan ⁇ 1 ) was 0.05.
  • Elastic layer 103 was prepared in the same manner as elastic layer 1, except that the ultraviolet ray irradiation conditions were changed.
  • the storage modulus at 25° C. was 0.50, and the loss tangent (tan ⁇ 1 ) was 0.40.
  • Elastic layer 104 was prepared in the same manner as elastic layer 1, except that the ultraviolet ray irradiation conditions were changed.
  • the storage modulus at 25° C. was 0.40, and the loss tangent (tan ⁇ 1 ) was 0.30.
  • Elastic layer 105 was prepared in the same manner as elastic layer 1, except that the ultraviolet ray irradiation conditions were changed.
  • the storage modulus at 25° C. was 11.00, and the loss tangent (tan ⁇ 1 ) was 0.14.
  • Optical Film 1 3.1.1) Thermoplastic (meth)acrylic resin
  • a MMA (methyl methacrylate)/PMI (phenylmaleimide)/MA (methyl acrylate) copolymer mass ratio of 85/10/5, Mw: 2 million, Tg: 122° C.
  • solution I The following components were charged into an 8 L polymerization apparatus equipped with a stirrer to prepare solution I.
  • Deionized water 180 parts by weight Polyoxyethylene lauryl ether phosphate 0.002 parts by weight Boric acid 0.4725 parts by weight Sodium carbonate 0.04725 parts by weight Sodium hydroxide 0.0076 parts by weight
  • a monomer mixture (c') consisting of the following components was prepared.
  • Methyl methacrylate (methyl methacrylate) 84.6% by mass
  • n-Butyl acrylate (n-butyl acrylate) 5.9% by mass
  • Styrene 7.9% by mass
  • Allyl methacrylate (allyl methacrylate) 0.5% by mass n-Octyl mercaptan 1.1% by mass
  • the following ingredients were then added: Potassium persulfate (added as a 2% by weight aqueous solution) 0.012 parts by weight
  • the polymerization reaction was continued for 120 minutes to obtain a soft layer (a layer made of acrylic rubber-like polymer (a)).
  • the glass transition temperature (Tg) of the soft layer calculated by averaging the glass transition temperatures of the homopolymers of the monomers constituting the acrylic rubber-like polymer (a) according to the composition ratio, was -30°C.
  • a monomer mixture (b') consisting of the following components was prepared.
  • Methyl methacrylate (methyl methacrylate) 97.5% by mass
  • n-Butyl acrylate (n-butyl acrylate) 2.5% by mass
  • the obtained methacrylic polymer (b) was poured into a 3% by mass aqueous solution of sodium sulfate to cause salting out and coagulation, and then repeatedly dehydrated and washed, and then dried to obtain acrylic graft copolymer particles (rubber particles) having a three-layer structure.
  • the average particle size of the obtained rubber particles was measured by a zeta potential/particle size measuring system "ELSZ-2000ZS" (manufactured by Otsuka Electronics Co., Ltd.) and found to be 200 nm.
  • the glass transition temperature (Tg) of the rubber particles was -30°C.
  • Optical Film 1 As a substrate, a PET film "TN100" (manufactured by Toyobo Co., Ltd., thickness 50 ⁇ m, with a release layer containing a non-silicone-based release agent) was prepared. A dope was applied onto the release layer of this PET film using a die by a backcoat method, and then dried at 80° C. in an atmosphere with a solvent concentration of 0.18% by volume. Then, the substrate was peeled off to obtain an optical film 1 with a thickness of 20 ⁇ m. The glass transition temperature (Tg) of the optical film was 10° C. In addition, the loss tangent (tan ⁇ 2 ) at 25° C. was 0.10.
  • Optical film 2 was prepared in the same manner as in preparation of optical film 1, except that the type of resin was changed to a cycloolefin resin (COP).
  • the loss tangent (tan ⁇ 2 ) at 25° C. was 0.08.
  • Optical films 3 to 6 were prepared in the same manner as in preparation of optical film 1, except that the content of rubber particles was changed to 10 mass%, 80 mass%, 5 mass%, and 90 mass%, respectively.
  • the loss tangent (tan ⁇ 2 ) at 25° C. was 0.08, 0.15, 0.07 and 0.15, respectively.
  • Optical films 7 and 8 were prepared in the same manner as in preparation of Optical Film 1, except that the particle size of the rubber particles was changed.
  • the loss tangent (tan ⁇ 2 ) at 25° C. was 0.14 and 0.08, respectively.
  • Optical film 101 was prepared in the same manner as in preparation of optical film 1, except that the type of resin was changed to polyethylene terephthalate (PET) and no rubber particles were added.
  • PET polyethylene terephthalate
  • the loss tangent (tan ⁇ 2 ) at 25° C. was 0.01.
  • Laminate 1 Preparation of Laminate 1
  • the thin glass 1 and the elastic layer 1 (elastic layer 1 prepared on optical film 1) were bonded together to obtain laminate 1 having the thin glass (glass layer), the elastic layer, and the optical film in this order.
  • the loss tangent ratio (tan ⁇ 1 /tan ⁇ 2 ) of Laminate 1 at 25° C. was 2.0.
  • the sample was placed on a flat surface with the bent inside facing down, and the haze of the bent portion was measured with a haze meter "NDH4000" (manufactured by Nippon Denshoku Industries Co., Ltd.).
  • the haze value before the bending test was a
  • the haze value after the bending test was b
  • the difference (b-a) between the values was obtained and evaluated according to the following criteria. If the evaluation is A or higher (A to AAA), it is practical.
  • AAA Less than 0.1.
  • AA 0.1 or more and less than 0.3.
  • B 0.8 or more and less than 1.1.
  • C 1.1 or more.
  • the examples and comparative examples show that the laminate of the present invention is able to achieve both impact resistance and flexibility in the glass layer.
  • Laminates 1 to 4 it can be seen that by having the storage modulus of the elastic layer at 25°C be in the range of 1.2 to 8.0 MPa, the impact resistance and flexibility of the glass layer are improved.
  • Laminates 1 and 6 show that the impact resistance and flexibility of the glass layer are improved by making the loss tangent ratio (tan ⁇ 1 /tan ⁇ 2 ) satisfy the above formula (2), and that damage to the internal module can be further suppressed.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Theoretical Computer Science (AREA)
  • Optics & Photonics (AREA)
  • Mechanical Engineering (AREA)
  • Laminated Bodies (AREA)

Abstract

La présente invention vise à fournir un stratifié et un corps d'affichage, dans lesquels à la fois une résistance aux chocs et des propriétés de courbure sont obtenues dans une couche de verre.　Ce stratifié a une couche de verre, une couche élastique et un film optique, le stratifié étant caractérisé par le fait que : le module d'élasticité de stockage de la couche élastique à 25 °C est dans la plage de 0,5 à 10,0 MPa ; le film optique contient des particules de caoutchouc ; et la valeur d'un rapport de tangentes de perte (tanδ1/tanδ2) satisfait à la formule (1), où tanδ1 et tanδ2 représentent les tangentes de perte respectives de la couche élastique et du film optique à 25 °C. Formule (1) : 1,0 ≤ tanδ1/tanδ2 ≤ 3,0.
PCT/JP2023/038692 2022-10-31 2023-10-26 Stratifié et dispositif d'affichage WO2024095890A1 (fr)

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2016194694A (ja) * 2015-03-31 2016-11-17 住友化学株式会社 粘着剤層付光学フィルム及び液晶表示装置
WO2019026577A1 (fr) * 2017-08-02 2019-02-07 バンドー化学株式会社 Feuille optique adhésive transparente, stratifié et structure liée
WO2019235160A1 (fr) * 2018-06-04 2019-12-12 株式会社カネカ Stratifié de verre, son procédé de production et panneau avant de dispositif d'affichage utilisant celui-ci
JP2020064271A (ja) * 2018-10-16 2020-04-23 住友化学株式会社 光学積層体および表示装置
JP2021009178A (ja) * 2019-06-28 2021-01-28 コニカミノルタ株式会社 光学フィルムおよび偏光板
JP7315110B2 (ja) * 2020-09-17 2023-07-26 コニカミノルタ株式会社 折り畳み可能なフレキシブルディスプレイのカバー部材、折り畳み可能なフレキシブルディスプレイのカバー部材用の基材フィルム、及びそれらを具備した表示装置

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2016194694A (ja) * 2015-03-31 2016-11-17 住友化学株式会社 粘着剤層付光学フィルム及び液晶表示装置
WO2019026577A1 (fr) * 2017-08-02 2019-02-07 バンドー化学株式会社 Feuille optique adhésive transparente, stratifié et structure liée
WO2019235160A1 (fr) * 2018-06-04 2019-12-12 株式会社カネカ Stratifié de verre, son procédé de production et panneau avant de dispositif d'affichage utilisant celui-ci
JP2020064271A (ja) * 2018-10-16 2020-04-23 住友化学株式会社 光学積層体および表示装置
JP2021009178A (ja) * 2019-06-28 2021-01-28 コニカミノルタ株式会社 光学フィルムおよび偏光板
JP7315110B2 (ja) * 2020-09-17 2023-07-26 コニカミノルタ株式会社 折り畳み可能なフレキシブルディスプレイのカバー部材、折り畳み可能なフレキシブルディスプレイのカバー部材用の基材フィルム、及びそれらを具備した表示装置

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