JP2022148070A - Optical laminate, picture display unit and adhesive composition - Google Patents

Abstract

To provide an optical laminate excellent in peel resistance at high temperature.SOLUTION: The optical laminate includes: an optical substrate; and an adhesive layer arranged on a surface of the optical substrate. The adhesive layer contains an adhesive composition containing a silane coupling agent. The silane coupling agent contains an isocyanuric ring, and does not contain an isocyanate group. The surface on which the adhesive layer is arranged is a surface modified by irradiation with energy.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD The present invention relates to an optical laminate, an image display device and an adhesive composition.

Various thin image display devices such as liquid crystal displays and organic EL displays usually include an optical laminate including an optical substrate and an adhesive layer disposed on the surface of the optical substrate. Examples of optical substrates are image forming layers such as liquid crystal layers and organic EL light emitting layers, optical films such as polarizing plates and retardation films, and cover windows. The pressure-sensitive adhesive layer is used for bonding each layer included in the optical layered body. Moreover, in an optical base material composed of a plurality of layers, for example, a polarizing plate composed of a polarizer and a polarizer protective film, the layers may be bonded together with an adhesive layer.

Patent Literature 1 discloses an optical laminate composed of a translucent adherend, a pressure-sensitive adhesive layer containing a specific silane coupling agent having an epoxy group at one end, and a polarizing plate. Patent Document 1 describes that the inclusion of the silane coupling agent can improve the adhesiveness of the pressure-sensitive adhesive layer to the glass plate.

JP-A-7-20314

Image display devices can be exposed to high temperatures. Therefore, the optical layered body is required to be resistant to peeling between the layers bonded via the pressure-sensitive adhesive layer even at high temperatures, in other words, to be excellent in peeling resistance at high temperatures. In addition, optical substrates other than glass substrates are frequently used in image display devices in order to reduce weight and improve functionality. It is However, according to studies by the present inventors, the optical layered body of Patent Document 1 cannot sufficiently cope with this problem.

An object of the present invention is to provide an optical layered body having excellent peeling resistance at high temperatures.

The present invention
comprising an optical substrate and a pressure-sensitive adhesive layer disposed on the surface of the optical substrate;
The pressure-sensitive adhesive layer contains a pressure-sensitive adhesive composition containing a silane coupling agent,
The silane coupling agent contains an isocyanuric ring and does not contain an isocyanate group,
The optical laminate, wherein the surface on which the pressure-sensitive adhesive layer is disposed is a modified surface that has been surface-modified by irradiation of energy;
I will provide a.

In another aspect, the invention provides a
the optical laminate of the present invention;
an image display device comprising an image display panel;
I will provide a.

In another aspect, the invention provides a
A pressure-sensitive adhesive composition used by being placed on the surface of an optical substrate for the optical layered body of the present invention,
containing a silane coupling agent,
The silane coupling agent contains an isocyanuric ring and does not contain an isocyanate group,
The pressure-sensitive adhesive composition, wherein the surface on which the pressure-sensitive adhesive composition is placed is a modified surface that has been surface-modified by irradiation of energy;
I will provide a.

ADVANTAGE OF THE INVENTION According to this invention, the optical laminated body excellent in peeling resistance at high temperature can be provided.

FIG. 1 is a cross-sectional view schematically showing an example of the optical layered body of the present invention. FIG. 2 is a cross-sectional view schematically showing another example of the optical layered body of the present invention. FIG. 3 is a cross-sectional view schematically showing yet another example of the optical layered body of the present invention. FIG. 4 is a cross-sectional view schematically showing an example of the image display device of the present invention. 5A is a diagram showing the distribution of the silane coupling agent in the pressure-sensitive adhesive layer of the optical layered body produced in Example 3. FIG. 5B is a diagram showing the distribution of the silane coupling agent in the adhesive layer of the optical layered body produced in Comparative Example 1. FIG.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the following embodiments.

[Optical laminate]
FIG. 1 shows the optical laminate of this embodiment. The optical layered body 100 of FIG. 1 includes an optical substrate 1 and an adhesive layer 2 . The adhesive layer 2 is arranged on the surface 11 of the optical substrate 1 . The adhesive layer 2 and the optical substrate 1 are in contact with each other. The surface 11 on which the pressure-sensitive adhesive layer 2 is arranged is a modified surface 12 that has been surface-modified by irradiation of energy. The adhesive layer 2 contains an adhesive composition containing a silane coupling agent (hereinafter referred to as "Si agent (X)") containing an isocyanuric ring but no isocyanate group. The isocyanuric ring has a structure represented by formula (1) below. A molecular structure (Y) containing a Si atom and a hydrolyzable group is bonded to at least one * (bonding hand) in formula (1). Molecular structure (Y) may be attached to two * or to all three *.

The inclusion of the Si agent (X) maintains the cohesive force of the adhesive layer 2 at high temperatures (for example, 50-100° C., typically 80° C.) and adheres to the modified surface 12 of the optical substrate 1 at high temperatures. It is thought that it contributes to the improvement of strength. Maintaining the cohesive strength, in other words, suppressing cohesive failure of the adhesive layer 2 and improving the adhesive strength work in the direction of improving the peeling resistance at high temperatures. (I) The distribution of the molecular structure (Y) that can form a covalent bond with the modified surface 12 in the pressure-sensitive adhesive layer 2, particularly the molecular structure (Y) is bonded to multiple * in the isocyanuric ring. (II) the NCO structure capable of forming a hydrogen bond with the modified surface 12 spreads evenly in three directions in the isocyanuric ring; and ( III) The NCO structure of the isocyanuric ring, unlike the isocyanate group, is difficult to form bonds with other materials that may be contained in the adhesive layer 2, such as polymers and cross-linking agents, and the cross-linked structure in the adhesive layer 2 is uniform. It is presumed that the ability to improve the According to the studies of the present inventors, the cohesive force of the pressure-sensitive adhesive layer 2 can be evaluated by 800% modulus.

In addition, the Si agent (X) can be relatively abundant in the region 21 near the interface 3 with the optical substrate 1 in the pressure-sensitive adhesive layer 2 . The uneven distribution in the region 21 can work in the direction of further improving the adhesive strength to the modified surface 12 at high temperatures. From the above aspect, the Si agent (X) may be unevenly distributed in the region 21 near the interface 3 with the optical substrate 1 in the pressure-sensitive adhesive layer 2 . The region 21 near the interface 3 means, for example, a region occupying 20% of the thickness of the adhesive layer 2 in the thickness direction of the adhesive layer 2 from the interface 3 . The distribution of the Si agent (X) in the adhesive layer 2 is confirmed by an evaluation method capable of elemental analysis in the thickness direction of the layer, such as time-of-flight secondary ion mass spectrometry (TOF-SIMS) using etching ions. can. The uneven distribution is confirmed, for example, by a plot obtained by TOF-SIMS, in which the horizontal axis is the etching time (corresponding to the thickness direction of the adhesive layer 2) and the vertical axis is the intensity of SiOH ⁺ (m/z=45). can. In the pressure-sensitive adhesive layer 2 in which the Si agent (X) is unevenly distributed, the sum of the areas of SiOH ⁺ peaks in the region 21 is 50% or more of the sum of the SiOH ⁺ peak areas measurable in the pressure-sensitive adhesive layer 2. 60% or more, 70% or more, 80% or more, or even 90% or more. Note that the intensity of SiOH ⁺ is a value (normalized intensity) that is normalized based on the intensity of ions that do not overlap m/z with SiOH ⁺ , as much is generated from the adhesive layer 2 during TOF-SIMS evaluation. There may be. When the pressure-sensitive adhesive layer 2 contains an acrylic pressure-sensitive adhesive composition, the ions are, for example, C ₂ H ₃ ⁺ .

In the example of FIG. 1, the pressure-sensitive adhesive layer 2 is arranged over the entire surface 11 of the optical substrate 1 . When viewed perpendicularly to the surface 11, the optical substrate 1 and the adhesive layer 2 have the same shape. However, the pressure-sensitive adhesive layer 12 may be arranged on at least part of the surface 11 . Further, the surface 11 in FIG. 1 is the modified surface 12 as a whole. However, at least part of the surface 11 may be the modified surface 12 .

[Si agent (X)]
Si agent (X) contains an isocyanuric ring. The number of isocyanuric rings contained in the Si agent (X) may be one, two or more, or one. In the Si agent (X), the number of Si atoms per isocyanuric ring may be 1, more than 1, 2 or more, or even 3 or more. The number of Si atoms contained in one molecular structure (Y) is not limited and is typically one.

A molecular structure containing a hydrolyzable group may be bonded to the Si atom of the Si agent (X). The hydrolyzable group is, for example, an alkoxy group having 1 to 4 carbon atoms, may be a methoxy group or an ethoxy group, or may be a methoxy group. A hydrolyzable group may be directly bonded to the Si atom.

Si agent (X) does not contain an isocyanate group. The Si agent (X) may not contain a reactive functional group other than an isocyanate group, and in particular may not contain a reactive functional group other than an isocyanate group at its terminal. However, hydrolyzable groups and isocyanuric rings bonded to Si atoms are excluded from the reactive functional groups. Examples of reactive functional groups are epoxy groups, amino groups, vinyl groups, styryl groups, (meth)acrylic groups, ureido groups, mercapto groups, in particular epoxy groups, amino groups and epoxy groups. These groups have lower reactivity with other materials that may be contained in the pressure-sensitive adhesive layer 2 compared to isocyanate groups. However, not containing a reactive functional group contributes to improving the uniformity of the crosslinked structure in the pressure-sensitive adhesive layer 2 . In addition, amino groups tend to react with materials other than polymers, such as cross-linking agents.

An example of Si agent (X) is shown in formula (2) below. Si agent (X) in formula (2) is a tris-(trialkoxysilylalkyl) isocyanurate. R ¹ , R ² and R ³ in formula (2) are each independently an alkylene group having 1 to 6 carbon atoms, may be an alkyl group having 2 to 4 carbon atoms, or may be a propyl group. good too. R ¹¹ , R ¹² , R ¹³ , R ²¹ , R ²² , R ²³ , R ³¹ , R ³² and R ³³ are each independently an alkoxy group having 1 to 4 carbon atoms, a methoxy group or an ethoxy group; It may be a methoxy group.

[Adhesive composition]
The content of the Si agent (X) in the adhesive composition contained in the adhesive layer 2 is, for example, 0.01% by weight or more and 5.0% by weight or less, and 0.01% by weight or more and 3.0% by weight or less. , 0.05 wt % or more and 1.0 wt % or less, 0.1 wt % or more and 0.5 wt % or less, or 0.15 wt % or more and 0.4 wt % or less. Appropriate control of the content contributes to more reliable improvement in peeling resistance at high temperatures.

The adhesive composition contains, for example, a (meth)acrylic polymer. The (meth)acrylic polymer may be the main component of the pressure-sensitive adhesive composition, in other words, the pressure-sensitive adhesive composition may be acrylic. An acrylic pressure-sensitive adhesive composition is excellent in various properties such as transparency, workability, durability and adhesion. However, the adhesive composition is not limited to acrylic. As used herein, (meth)acryl means acryl and/or methacryl. Moreover, a main component means the component with the largest content rate in a composition. The content of the main component is, for example, 50% by weight or more, 70% by weight or more, 80% by weight or more, 90% by weight or more, 95% by weight or more, 97% by weight or more, 98% by weight or more, or even 99% by weight. or more.

The pressure-sensitive adhesive composition may contain one or more (meth)acrylic polymers.

<(Meth)acrylic polymer>
The (meth)acrylic polymer may have a unit (a2) derived from a (meth)acrylic monomer (a1) having an alkyl group having 1 to 30 carbon atoms in a side chain, and the unit (a2 ) as a main unit. The alkyl group may be linear or branched. The (meth)acrylic polymer may have one or more units (a2).

Examples of monomers (a1) are methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, isobutyl (meth) Acrylate, n-pentyl (meth)acrylate, isopentyl (meth)acrylate, n-hexyl (meth)acrylate, isohexyl (meth)acrylate, isoheptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate ) acrylate, isooctyl (meth) acrylate, n-nonyl (meth) acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, n-dodecyl (meth) acrylate (lauryl (meth) acrylate ), n-tridecyl (meth)acrylate and n-tetradecyl (meth)acrylate. As used herein, the term "main unit" refers to the total structural units of the polymer, for example 50% by weight or more, preferably 80% by weight or more, more preferably 90% by weight or more, and still more preferably 94% by weight or more. means unit. The upper limit of the ratio of the main units is, for example, 99.9% by weight or less, and may be 99.5% by weight or less.

The (meth)acrylic polymer may have units (a2) derived from the monomer (a1) having a long-chain alkyl group in the side chain. The monomer (a1) is, for example, n-dodecyl (meth)acrylate. As used herein, a long-chain alkyl group means an alkyl group having 6 to 30 carbon atoms.

The (meth)acrylic polymer may have units (a2) derived from the monomer (a1) having a Tg in the range of -70°C to -20°C when homopolymerized. The unit (a1) is, for example, 2-ethylhexyl acrylate.

The (meth)acrylic polymer may have units other than the unit (a1). The unit is, for example, a unit (b2) derived from a monomer (b1) copolymerizable with the monomer (a1). The (meth)acrylic polymer may have one or more units (b2).

An example of the monomer (b1) is a (meth)acrylic monomer (c1) having a hydroxyl group. The monomer (b1) may be a hydroxyl group-containing (meth)acrylate monomer. Examples of monomers (c1) are 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylates, hydroxyalkyl (meth)acrylates such as 10-hydroxydecyl (meth)acrylate and 12-hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)-methylacrylate. The monomer (c1) may be 2-hydroxyethyl (meth)acrylate or 4-hydroxybutyl (meth)acrylate because it can improve the durability of the pressure-sensitive adhesive composition.

The monomer (b1) may be an amino group-containing monomer or an amide group-containing monomer. Examples of amino group-containing monomers are N,N-dimethylaminoethyl (meth)acrylate and N,N-dimethylaminopropyl (meth)acrylate. Examples of amide group-containing monomers are (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-isopropylacrylamide, N-methyl(meth)acrylamide, N- Butyl (meth)acrylamide, N-hexyl (meth)acrylamide, N-methylol (meth)acrylamide, N-methylol-N-propane (meth)acrylamide, aminomethyl (meth)acrylamide, aminoethyl (meth)acrylamide, mercaptomethyl (Meth) acrylamide-based monomers such as mercaptoethyl (meth) acrylamide; and N-vinyl group-containing lactam monomers such as N-vinylpyrrolidone and N-vinyl-ε-caprolactam.

The monomer (b1) may be a carboxyl group-containing monomer. Examples of carboxyl group-containing monomers are (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid. However, the unit derived from the carboxyl group-containing monomer has a strong effect of increasing the elastic modulus of the adhesive layer 2, and the degree of freedom in designing the physical properties of the adhesive layer 2 containing the (meth)acrylic polymer having the unit. is trending downward. In addition, the (meth)acrylic polymer having the unit may have corrosiveness to the optical substrate depending on the material contained in the optical substrate. From this point of view, the content of units derived from a carboxyl group-containing monomer in the (meth)acrylic polymer is preferably 5% by weight or less, 3% by weight or less, 1.5% by weight or less, and 1% by weight. It may be 0.5% by weight or less, or even 0% by weight (not including the unit).

Monomer (b1) may be a polyfunctional monomer. The gel fraction of the pressure-sensitive adhesive composition can be adjusted by using polyfunctional monomers. Examples of multifunctional monomers are hexanediol di(meth)acrylate (1,6-hexanediol di(meth)acrylate), butanediol di(meth)acrylate, (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, trimethylolpropane tri( polyfunctional acrylates such as meth)acrylates, tetramethylolmethane tri(meth)acrylates, allyl (meth)acrylates, vinyl (meth)acrylates, epoxy acrylates, polyester acrylates and urethane acrylates; and divinylbenzene. Polyfunctional acrylates are preferably 1,6-hexanediol diacrylate and dipentaerythritol hexa(meth)acrylate.

Examples of monomers (b1) other than those mentioned above include 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, methoxytriethylene glycol (meth)acrylate, (meth)acrylic (Meth)acrylic acid alkoxyalkyl esters such as 3-methoxypropyl acid, 3-ethoxypropyl (meth)acrylate, 4-methoxybutyl (meth)acrylate and 4-ethoxybutyl (meth)acrylate; (meth)acrylic acid Epoxy group-containing monomers such as glycidyl acid and methyl glycidyl (meth)acrylate; sulfonic acid group-containing monomers such as sodium vinyl sulfonate; phosphoric acid group-containing monomers; ) (meth)acrylates having an alicyclic hydrocarbon group such as cyclohexyl acrylate and isobornyl (meth)acrylate; fragrances such as phenyl (meth)acrylate, phenoxyethyl (meth)acrylate and benzyl (meth)acrylate vinyl esters such as vinyl acetate and vinyl propionate; aromatic vinyl compounds such as styrene and vinyl toluene; olefins or dienes such as ethylene, propylene, butadiene, isoprene and isobutylene vinyl ethers such as vinyl alkyl ether; and vinyl chloride.

Units derived from a (meth)acrylic monomer (c1) having a hydroxyl group, an amino group-containing monomer, an amide group-containing monomer, and a polyfunctional monomer in a (meth)acrylic polymer The total content is, for example, 20% by weight or less, and may be 10% by weight or less, 8% by weight or less, or even 5% by weight or less. When the (meth)acrylic polymer has the unit, the total content of the unit is, for example, 0.01% by weight or more, and may be 0.05% by weight or more.

The total content of units (b2) derived from the monomer (b1) in the (meth)acrylic polymer is, for example, 30% by weight or less, may be 10% by weight or less, or may be 0% by weight (the without units).

The (meth)acrylic polymer can be formed by polymerizing a monomer group containing the above monomers by a known method. A monomer and a partial polymer of the monomer may be polymerized. Polymerization can be carried out, for example, by solution polymerization, emulsion polymerization, bulk polymerization, thermal polymerization, or active energy ray polymerization. Polymerization is preferably solution polymerization or active energy ray polymerization, since a pressure-sensitive adhesive composition having excellent optical transparency can be formed. Polymerization is preferably carried out while avoiding contact of the monomer and/or partial polymer with oxygen. Polymerization in shutdown can be employed. The (meth)acrylic polymer to be formed may be in any form such as a random copolymer, a block copolymer, a graft copolymer, or may be a random copolymer.

The polymerization system forming the (meth)acrylic polymer may contain one or more polymerization initiators. The type of polymerization initiator can be selected depending on the polymerization reaction, and may be, for example, a photopolymerization initiator or a thermal polymerization initiator.

Solvents used for solution polymerization include esters such as ethyl acetate and n-butyl acetate; aromatic hydrocarbons such as toluene and benzene; aliphatic hydrocarbons such as n-hexane and n-heptane; alicyclic hydrocarbons such as methylcyclohexane; and ketones such as methyl ethyl ketone and methyl isobutyl ketone. However, the solvent is not limited to the above examples. The solvent may be a mixed solvent of two or more solvents.

Polymerization initiators used for solution polymerization are, for example, azo polymerization initiators, peroxide polymerization initiators, and redox polymerization initiators. Peroxide polymerization initiators are, for example, dibenzoyl peroxide and t-butyl permaleate. Among them, the azo polymerization initiator disclosed in JP-A-2002-69411 is preferable. The azo polymerization initiator, for example, 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis-2-methylbutyronitrile, 2,2'-azobis (2-methylpropion acid) dimethyl, 4,4'-azobis-4-cyanovaleric acid. However, the polymerization initiator is not limited to the above examples. The amount of the azo polymerization initiator used is, for example, 0.05 to 0.5 parts by weight, and may be 0.1 to 0.3 parts by weight, per 100 parts by weight of the total amount of the monomers.

Active energy rays used for active energy ray polymerization include, for example, ionizing radiation such as α rays, β rays, γ rays, neutron beams and electron beams, and ultraviolet rays. The active energy rays are preferably ultraviolet rays. Polymerization by irradiation with ultraviolet rays is also called photopolymerization. A polymerization system for active energy ray polymerization typically contains a photopolymerization initiator. Polymerization conditions for active energy polymerization are not limited as long as a (meth)acrylic polymer is formed.

Photopolymerization initiators include, for example, benzoin ether-based photopolymerization initiators, acetophenone-based photopolymerization initiators, α-ketol-based photopolymerization initiators, aromatic sulfonyl chloride-based photopolymerization initiators, and photoactive oxime-based photopolymerization initiators. , a benzoin-based photopolymerization initiator, a benzyl-based photopolymerization initiator, a benzophenone-based photopolymerization initiator, a ketal-based photopolymerization initiator, and a thioxanthone-based photopolymerization initiator. However, the photopolymerization initiator is not limited to the above examples.

Benzoin ether-based photopolymerization initiators include, for example, benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dimethoxy-1,2-diphenylethan-1-one, anisolemethyl is ether. Acetophenone-based photopolymerization initiators include, for example, 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexylphenylketone, 4-phenoxydichloroacetophenone, 4-(t-butyl)dichloro Acetophenone. Examples of α-ketol photopolymerization initiators are 2-methyl-2-hydroxypropiophenone and 1-[4-(2-hydroxyethyl)phenyl]-2-methylpropan-1-one. The aromatic sulfonyl chloride photopolymerization initiator is, for example, 2-naphthalenesulfonyl chloride. A photoactive oxime-based photopolymerization initiator is, for example, 1-phenyl-1,1-propanedione-2-(o-ethoxycarbonyl)-oxime. A benzoin-based photopolymerization initiator is, for example, benzoin. A benzylic photopolymerization initiator is, for example, benzyl. Examples of benzophenone-based photopolymerization initiators include benzophenone, benzoylbenzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, and α-hydroxycyclohexylphenyl ketone. A ketal photopolymerization initiator is, for example, benzyl dimethyl ketal. Thioxanthone-based photopolymerization initiators are, for example, thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, and dodecylthioxanthone.

The amount of the photopolymerization initiator used is, for example, 0.01 to 1 part by weight, and may be 0.05 to 0.5 part by weight, per 100 parts by weight of the total amount of the monomers.

In addition, the polyfunctional monomer (multifunctional acrylate etc.) which is a monomer (b1) can be used for both a solvent type and an active-energy-ray-curable adhesive composition. When both a polyfunctional monomer and a photopolymerization initiator are used for a solvent-based adhesive composition, for example, after removing the solvent by heat drying, the adhesive composition is irradiated with an active energy ray. is allowed to proceed.

The weight average molecular weight (Mw) of the (meth)acrylic polymer is, for example, 1 million or more, and may be 1.2 million or more, 1.5 million or more, 1.8 million or more, or even 2 million or more. The upper limit of Mw is, for example, 3,000,000 or less.

The molecular weight distribution (Mw/number average molecular weight (Mn)) of the (meth)acrylic polymer is, for example, 2-20, and may be 4-15. The Mw and Mn of polymers and oligomers in this specification are values (converted to polystyrene) based on GPC (gel permeation chromatography) measurement.

The content of the (meth)acrylic polymer in the pressure-sensitive adhesive composition is, for example, 50% by weight or more, 60% by weight or more, and may be 70% by weight or more in terms of solid content.

<(Meth) acrylic oligomer>
The pressure-sensitive adhesive composition may further contain a (meth)acrylic oligomer.

The (meth)acrylic oligomer can have the same composition as the (meth)acrylic polymer described above, except that the Mw is different. Mw of the (meth)acrylic oligomer is, for example, 1000 or more, and may be 2000 or more, 3000 or more, or even 4000 or more. The upper limit of Mw of the (meth)acrylic oligomer is, for example, 30,000 or less, and may be 15,000 or less, 10,000 or less, or even 7,000 or less.

The (meth)acrylic oligomer has, for example, one or more structural units derived from the following monomers: methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate. , isopropyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate ) acrylate, 2-ethylhexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate ) acrylates, alkyl (meth)acrylates such as undecyl (meth)acrylate and dodecyl (meth)acrylate; esters with alicyclic alcohols; aryl (meth)acrylates such as phenyl (meth)acrylate and benzyl (meth)acrylate; and (meth)acrylates obtained from terpene compound derivative alcohols.

The (meth)acrylic oligomer may have structural units derived from acrylic monomers having a relatively bulky structure. Examples of the acrylic monomer include alkyl (meth)acrylates having a branched alkyl group such as isobutyl (meth)acrylate and t-butyl (meth)acrylate; cyclohexyl (meth)acrylate and isobornyl (meth)acrylate. and esters of (meth)acrylic acid with cycloaliphatic alcohols such as dicyclopentanyl (meth)acrylate; aryl (meth)acrylates such as phenyl (meth)acrylate and benzyl (meth)acrylate. The acrylic monomer preferably has a cyclic structure, and more preferably has two or more cyclic structures. Further, when the (meth)acrylic oligomer is polymerized and/or the adhesive composition is irradiated with ultraviolet rays, the progress of polymerization and/or formation is hardly inhibited, so the acrylic monomer preferably does not have an unsaturated bond. For example, alkyl (meth)acrylates having branched alkyl groups and esters of (meth)acrylic acid and alicyclic alcohol can be used.

Specific examples of (meth)acrylic oligomers include copolymers of butyl acrylate, methyl acrylate and acrylic acid, copolymers of cyclohexyl methacrylate and isobutyl methacrylate, copolymers of cyclohexyl methacrylate and isobornyl methacrylate, cyclohexyl Copolymers of methacrylate and acryloylmorpholine, copolymers of cyclohexyl methacrylate and diethylacrylamide, copolymers of 1-adamantyl acrylate and methyl methacrylate, copolymers of dicyclopentanyl methacrylate and isobornyl methacrylate, Copolymers of methyl methacrylate and at least one selected from dicyclopentanyl methacrylate, cyclohexyl methacrylate, isobornyl methacrylate, isobornyl acrylate and cyclopentanyl methacrylate, homopolymers of dicyclopentanyl acrylate, 1- They are homopolymers of adamantyl methacrylate and homopolymers of 1-adamantyl acrylate.

As the method for polymerizing the (meth)acrylic oligomer, the method for polymerizing the (meth)acrylic polymer described above can be employed.

When the pressure-sensitive adhesive composition contains a (meth)acrylic oligomer, the amount thereof is, for example, 70 parts by weight or less, 50 parts by weight or less, or even 40 parts by weight with respect to 100 parts by weight of the (meth)acrylic polymer. It may be less than part. The lower limit of the amount to be blended is, for example, 0.05 parts by weight or more, and may be 0.1 parts by weight or more, or further 0.2 parts by weight or more with respect to 100 parts by weight of the (meth)acrylic polymer. The pressure-sensitive adhesive composition may not contain a (meth)acrylic oligomer.

The (meth)acrylic oligomer can be used in both solvent-type and active energy ray-curable pressure-sensitive adhesive compositions. However, when used in an active energy ray-curable pressure-sensitive adhesive composition, if the (meth)acrylic oligomer is dissolved in a solvent, the mixture containing the (meth)acrylic oligomer For example, after removing the solvent by heat drying, curing by irradiation with active energy rays may proceed.

<Crosslinking agent>
The adhesive composition may further contain a cross-linking agent. The use of a cross-linking agent can improve the cohesive strength of the pressure-sensitive adhesive composition.

Examples of crosslinkers are organic crosslinkers and multifunctional metal chelates. Examples of organic cross-linking agents are isocyanate cross-linking agents, peroxide cross-linking agents, epoxy cross-linking agents and imine cross-linking agents. A polyfunctional metal chelate has a structure in which a polyvalent metal and an organic compound are covalently or coordinately bonded. Polyvalent metals are, for example, Al, Cr, Zr, Co, Cu, Fe, Ni, V, Zn, In, Ca, Mg, Mn, Y, Ce, Sr, Ba, Mo, La, Sn, Ti. be. Atoms in organic compounds to which polyvalent metals are covalently or coordinately bonded are typically oxygen atoms. Examples of organic compounds are alkyl esters, alcohol compounds, carboxylic acid compounds, ether compounds and ketone compounds. The organic cross-linking agent and polyfunctional metal chelate can be used for both solvent-type and active energy ray-curable pressure-sensitive adhesive compositions.

When the pressure-sensitive adhesive composition is a solvent type, the cross-linking agent is preferably an isocyanate-based cross-linking agent or a peroxide-based cross-linking agent. The isocyanate-based cross-linking agent may be bifunctional or trifunctional. However, a trifunctional cross-linking agent is preferred in order to maintain cohesive strength at high temperatures. A trifunctional cross-linking agent forms a three-dimensional cross-linking structure. Also, an isocyanate-based cross-linking agent and a peroxide-based cross-linking agent may be used in combination. By using them together, it is possible to further improve the adhesive force while maintaining the cohesive force at high temperatures. The isocyanate-based cross-linking agent used in combination is preferably trifunctional.

When the pressure-sensitive adhesive composition contains a cross-linking agent, the amount thereof is, for example, 0.01 to 10 parts by weight, 0.1 to 5 parts by weight, or even 0.1 to 5 parts by weight with respect to 100 parts by weight of the (meth)acrylic polymer. It may be 0.1 to 3 parts by weight.

When the isocyanate-based cross-linking agent is used alone, its blending amount is, for example, 0.01 to 3 parts by weight, 0.01 to 1 part by weight, 0.01 to 1 part by weight, and 0.01 to 1 part by weight, based on 100 parts by weight of the (meth)acrylic polymer. 01 to 0.5 parts by weight, or even 0.01 to 0.3 parts by weight.

When an isocyanate cross-linking agent and a peroxide cross-linking agent are used in combination, the weight ratio of the peroxide cross-linking agent to the isocyanate cross-linking agent is, for example, 1.0 or more, 1.2 or more, or 1.5 or more. , and may be two or more. Moreover, the upper limit of the weight ratio is, for example, 500 or less, and may be 300 or less, or even 200 or less.

<Additive>
The adhesive composition may contain other additives. Additives include, for example, silane coupling agents other than the Si agent (X), silicone compounds such as silicone oil (excluding silane coupling agents), polyether compounds (polyalkylene glycols such as polypropylene glycol, etc.), pigments And coloring agents such as dyes, surfactants, plasticizers, tackifiers, surface lubricants, leveling agents, softeners, antioxidants, anti-aging agents, light stabilizers, ultraviolet absorbers, polymerization inhibitors, electrification Inhibitors (ionic compounds such as alkali metal salts, ionic liquids, and ionic solids), inorganic fillers, organic fillers, powders such as metal powders, particles, and foil-like materials. When a silane coupling agent other than the Si agent (X) is included, the content of the silane coupling agent is 0.5% by weight or less, 0.1% by weight or less, 0.05% by weight or less, and further 0.5% by weight or less. may be less than 01% by weight. The adhesive composition may not contain a silane coupling agent other than the Si agent (X). When a silicone compound is included, the content of the silicone compound may be 0.5% by weight or less, 0.1% by weight or less, 0.05% by weight or less, or even less than 0.01% by weight. The adhesive composition does not have to contain a silicone compound.

[Adhesive layer]
The thickness of the adhesive layer 2 is, for example, 1 to 200 μm, may be 5 to 150 μm, and may be 10 to 100 μm. The adhesive layer 2 may be a single layer or a laminate containing two or more layers. All two or more layers may contain the pressure-sensitive adhesive composition.

The 800% modulus of the adhesive layer 2 at 80° C. is, for example, 0.18 to 0.5 N/mm ² , 0.2 to 0.4 N/mm ² , further 0.2 to 0.3 N/mm ² . may be The 800% modulus means that the stress (tensile stress) generated in the adhesive layer 2 when the adhesive layer 2 is stretched by 800% by a tensile force in one direction is divided by the initial cross-sectional area of the adhesive layer 2. It is a characteristic represented by a value obtained by The 800% modulus of the adhesive layer 2 can be evaluated as follows.

The pressure-sensitive adhesive layer 2 to be evaluated is cut into strips of 30 mm×100 mm. Next, the cut pressure-sensitive adhesive layer 2 is wound in the direction of the long side so as not to contain air bubbles, to obtain a cylindrical test piece having a height of 30 mm corresponding to the length of the short side. Next, the obtained test piece is set in a tensile tester such as Tensilon, and a uniaxial tensile test is performed in the height direction to obtain an elongation-stress curve of the pressure-sensitive adhesive layer 2 . The preparation of the test piece and the uniaxial tensile test are carried out at 23° C., the initial distance between the chucks in the uniaxial tensile test is 10 mm, and the tensile speed is 300 mm/min. From the resulting elongation-stress curve, the stress at 800% elongation (at this time, the distance between chucks is 90 mm) is obtained, and this is divided by the initial cross-sectional area of the test piece to obtain the 800% modulus of the adhesive layer 2. .

The adhesive strength of the adhesive layer 2 to a polyethylene terephthalate (PET) film at 80° C. is, for example, 1.8 N/25 mm or more, 2.0 N/25 mm or more, 2.5 N/25 mm or more, 2.7 N/25 mm or more, It may be 3.0 N/25 mm or more, 3.2 N/25 mm or more, or even 3.5 N/25 mm or more. The upper limit of adhesive strength is, for example, 10.0 N/25 mm or less. However, the adhesive strength is evaluated with the adhesive layer 2 placed on the modified surface of the PET film. In other words, the adhesion is the adhesion to the modified surface of the PET film.

The total light transmittance (according to JIS K7136) of the pressure-sensitive adhesive layer 2 in the visible light wavelength region is preferably 85% or more, more preferably 90% or more.

The pressure-sensitive adhesive composition described above is a pressure-sensitive adhesive composition that is used by being placed on the modified surface 12 of the optical substrate 1 in the optical laminate 1 . From this aspect, the present invention provides
In the optical laminate 1, a pressure-sensitive adhesive composition used by being arranged on the surface 11 of the optical substrate 1,
containing a silane coupling agent,
The silane coupling agent contains an isocyanuric ring and does not contain an isocyanate group,
The pressure-sensitive adhesive composition, wherein the surface on which the pressure-sensitive adhesive composition is placed is a modified surface that has been surface-modified by irradiation of energy;
I will provide a.

[Formation of adhesive layer]
The adhesive layer 2 can be formed, for example, by the following method.
- A solvent-type adhesive composition is applied to a separator (release film) or the like, and the polymerization solvent or the like is removed by drying. The adhesive layer 2 formed on the separator can be transferred to the surface 11 of the optical substrate 1 .
- An active energy ray-curable pressure-sensitive adhesive composition is applied to a separator or the like and cured by irradiating it with an active energy ray. In addition to irradiation with active energy rays, drying by heating may be performed. Moreover, when applying the pressure-sensitive adhesive composition, one or more solvents other than the polymerization solvent may be newly added to the composition.

The pressure-sensitive adhesive composition-applied surface of the separator may be subjected to release treatment. An example of a release treatment is silicone treatment using a silicone compound.

The drying temperature is, for example, 40 to 200°C, may be 50 to 180°C, and further may be 70 to 170°C. However, it can be adjusted by the composition of the pressure-sensitive adhesive composition.

The drying time is, for example, 5 seconds to 20 minutes, and may be 5 seconds to 10 minutes, or even 10 seconds to 5 minutes. However, it can be adjusted by the composition of the pressure-sensitive adhesive composition.

The pressure-sensitive adhesive composition can be used, for example, in 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, die coater, etc. It can be applied by an extrusion coating method.

[Optical substrate]
The optical substrate 1 has a modified surface 12 . The modified surface 12 is a surface that has undergone surface modification by energy irradiation. In surface modification, functional groups are generated on the surface of the substrate. Surface modification by energy irradiation is, for example, at least one selected from corona treatment, plasma treatment, and ultraviolet treatment (excimer laser irradiation, etc.).

Energy irradiation can be carried out, for example, in an atmosphere containing an inert gas such as nitrogen or in air. The amount of energy to be irradiated is, for example, 0.05 to 20 J/cm ² and may be 0.1 to 5 J/cm ² . A known method can be applied to the energy irradiation in each treatment.

The optical substrate 1 may be made of resin, in other words, it may be a resin substrate. Moreover, at this time, the Si agent (X) may be unevenly distributed in the region 21 near the interface 3 with the optical substrate 1 in the adhesive layer 2 . However, the optical substrate 1 is not limited to a resin substrate. Examples of the resin forming the optical substrate 1 are polyester such as PET, acrylic resin, polyolefin, polycycloolefin, polyimide, polyurethane, and modified cellulose such as triacetylcellulose (TAC). The acrylic resin may have a ring structure such as an amide ring, an imide ring, an acid anhydride ring, and a lactone ring. However, the resin is not limited to the above examples.

Examples of the optical substrate 1 include optical compensation films such as polarizing films, polarizer protective films, retardation films, and viewing angle compensation films, antireflection films, antistatic films, conductive films, cushion films, decorative films, and cover windows. , image forming layers such as a liquid crystal layer and an organic EL light emitting layer, and laminates thereof. However, the optical substrate 1 is not limited to the above example, and may be any optical substrate used in an image display device, for example.

A polarizing film contains a polarizer. A polarizer protective film may be bonded to at least one surface of the polarizer via an adhesive layer. A polarizer is typically a polyvinyl alcohol (PVA) film in which iodine is oriented by various methods such as stretching in air (dry stretching), stretching in boric acid solution, and coating.

A retardation film is a film having birefringence in the in-plane direction and/or the thickness direction. A retardation film is, for example, a stretched resin film or a film in which a liquid crystal material is oriented and fixed.

Retardation film, for example, λ / 4 plate, λ / 2 plate, antireflection retardation film (see, for example, paragraphs 0221, 0222, 0228 of JP-A-2012-133303), viewing angle compensation retardation film ( For example, see paragraphs 0225 and 0226 of JP-A-2012-133303), obliquely oriented retardation film for viewing angle compensation (see paragraph 0227 of JP-A-2012-13303, for example). However, the retardation film is not limited to the above examples as long as it has birefringence in the in-plane direction and/or the thickness direction. The retardation value of the retardation film, the arrangement angle, the three-dimensional birefringence, whether it is a single layer or a multilayer, and the like are not limited. A retardation film can be a known film.

The thickness of the retardation film is, for example, 50 μm or less, and may be 20 μm or less, 10 μm or less, or even 1 to 9 μm.

The thickness of the optical substrate 1 is, for example, 1 μm or more, and may be 5 μm or more, or even 25 μm or more. The upper limit of the thickness of the optical substrate 1 is, for example, 200 μm or less.

The total light transmittance of the optical substrate 1 in the visible light wavelength range (according to JIS K7136) is preferably 85% or more, more preferably 90% or more.

The total light transmittance (according to JIS K7136) of the optical layered body 100 in the visible light wavelength region is preferably 85% or more, more preferably 90% or more.

The optical layered body 100 of FIG. 1 includes one optical substrate 1 and one adhesive layer 2 . The optical layered body of the present invention may comprise two or more optical substrates 1 and/or two or more adhesive layers 2 . In other words, the optical laminate of the present invention comprises at least one optical substrate 1 and at least one adhesive layer 2 .

The optical laminate 110 of FIG. 2 includes a retardation film 4, polarizer protective films 5A and 5B, a polarizer 6 and adhesive layers 7A, 7B and 7C. In the optical laminate 110, the retardation film 4, the adhesive layer 7A, the polarizer protective film 5A, the adhesive layer 7B, the polarizer 6, the adhesive layer 7C and the polarizer protective film 5B are laminated in this order. At least one adhesive layer selected from the three adhesive layers 7A, 7B, and 7C is the adhesive layer 2 described above. All of the adhesive layers 7A, 7B, and 7C may be the adhesive layer 2. At least one of the optical substrates in contact with the pressure-sensitive adhesive layer 2 is the optical substrate 1 described above. Both optical substrates in contact with the pressure-sensitive adhesive layer 2 may be the optical substrate 1 described above.

When the optical layered body 110 has two or more pressure-sensitive adhesive layers 2, the composition of the pressure-sensitive adhesive composition contained in each pressure-sensitive adhesive layer 2 may be the same or different.

The optical layered body of the present invention may be an optical substrate with a pressure-sensitive adhesive layer that is used by being attached to another member.

FIG. 3 shows an example of an optical substrate with an adhesive layer. The adhesive layer-attached optical substrate 120 of FIG. and The separator 8 has a function of protecting the pressure-sensitive adhesive layer 2 during distribution and storage of the pressure-sensitive adhesive layer-attached optical substrate 120, and is peeled off when the pressure-sensitive adhesive layer-attached optical substrate 120 is used.

Separator 8 is typically a resin film. Examples of resins forming the separator 8 are polyester such as PET, polyolefin such as polyethylene and polypropylene, polycarbonate, acrylic resin, polystyrene, polyamide and polyimide. The surface of the separator 8 that comes into contact with the pressure-sensitive adhesive layer 2 may be subjected to release treatment. The release treatment is, for example, silicone treatment with a silicone compound. However, the separator 8 is not limited to the above example.

The thickness of the separator 8 is, for example, 20 μm to 100 μm.

The adhesive-attached optical substrate 120 may comprise two or more optical substrates 1 and/or two or more adhesive layers 2 . In the adhesive-attached optical substrate 120 having two or more adhesive layers, at least one adhesive layer may be the adhesive layer 2 described above.

The optical layered body of the present invention may comprise arbitrary layers other than those described above.

The optical layered body of the present invention can be distributed and stored, for example, in the form of a sheet or as a wound body obtained by winding a belt-shaped layered body.

The optical laminate of the present invention may be used for image display devices.

[Image display device]
An example of an image display device is shown in FIG. In the image display device 200 of FIG. 4, a substrate 51, an adhesive layer 10A, an image forming layer (organic EL layer) 52, an adhesive layer 10B, an optical substrate 1, an adhesive layer 2 and a cover film 53 are laminated in this order. It has a laminated structure. The image display device 200 includes an optical layered body 100 . The substrate 51, the image forming layer 52, and the cover film 53 may have the same configurations as those of the substrate, image forming layer, and cover film of a known organic EL display.

At least one selected from the adhesive layers 10A and 10B may be the adhesive layer 2 described above. In this case, at least one member in contact with the pressure-sensitive adhesive layers 10A and 10B that are the pressure-sensitive adhesive layer 2 is the optical substrate 1 .

The image display device 200 in FIG. 4 is an organic EL display. However, the image display device 8 of the present invention is not limited to the above example.

The image display device 200 can have any configuration as long as it includes the optical layered body of the present invention.

The image display device 200 may be a flexible image display device.

EXAMPLES The present invention will be described in more detail below with reference to examples. The invention is not limited to the examples shown below.

The correspondence between the abbreviations or names shown in the following description and the compounds is as follows.
BA: Butyl acrylate HBA: Hydroxybutyl acrylate 2EHA: 2-Ethylhexyl acrylate NVP: N-vinylpyrrolidone D110N: Trimethylolpropane/xylylene diisocyanate adduct (Mitsui Chemical Takenate D110N, isocyanate cross-linking agent)
BPO: benzoyl peroxide (peroxide cross-linking agent)
KBM9659: tris-(trimethoxysilylpropyl) isocyanurate (manufactured by Shin-Etsu Chemical, Si agent (X))
KBM403: 3-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical, a silane coupling agent having an epoxy group at its end)
KBM573: N-phenyl-3-aminopropyltrimethoxysilane (manufactured by Shin-Etsu Chemical, silane coupling agent having an amino group)

[Preparation of (meth)acrylic polymer]
(Synthesis example 1)
99 parts by weight of BA and 1 part by weight of HBA were charged into a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser, and ethyl acetate was added so that the concentration of the mixture of BA and HBA was 50% by weight. and solvent diluted with toluene. The proportion of toluene in the solvent used for dilution was 5% by weight. Next, 0.1 part by weight of AIBN as a polymerization initiator was added to 100 parts by weight of a mixture of BA and HBA, and nitrogen gas was introduced while gently stirring to replace the inside of the flask with nitrogen. The temperature was kept around 55° C. and the polymerization reaction was allowed to proceed for 7 hours. Next, ethyl acetate was added to the obtained reaction solution to adjust the solid content concentration to 20% by weight to obtain a solution of (meth)acrylic polymer A1. The (meth)acrylic polymer A1 had an Mw of 1,800,000. The Mw of the (meth)acrylic polymer produced in each synthesis example was measured by GPC under the following measurement conditions.
・ Analyzer: Acquity APC manufactured by Waters
・Column: G7000HXL+GMHXL+GMHXL manufactured by Tosoh
・Column temperature: 40°C
・Eluent: tetrahydrofuran (acid added)
・Flow rate: 0.8 mL/min ・Injection volume: 100 μL
・Detector: Differential refractometer (RI)
・ Standard sample: Polystyrene (PS) manufactured by Agilent

(Synthesis example 2)
(Meth)acrylic polymer A2 was prepared in the same manner as in Synthesis Example 1, except that 96 parts by weight of 2EHA, 1 part by weight of HBA, and 3 parts by weight of NVP were charged in a flask, and the proportion of toluene in the solvent used for dilution was changed to 30% by weight. A solution of The (meth)acrylic polymer A2 had an Mw of 1,200,000.

(Synthesis Example 3)
A solution of (meth)acrylic polymer A3 was obtained in the same manner as in Synthesis Example 2, except that the proportion of toluene in the solvent used for dilution was changed to 5% by weight. The (meth)acrylic polymer A3 had an Mw of 2,000,000.

(Synthesis Example 4)
In the same manner as in Synthesis Example 2, except that the ratio of toluene in the solvent used for dilution was 0% by weight, the amount of the polymerization initiator was 0.05 parts by weight of AIBN, and the polymerization reaction time was 2 hours. ) A solution of acrylic polymer A4 was obtained. The (meth)acrylic polymer A4 had an Mw of 2,800,000.

The (meth)acrylic polymers produced in each synthesis example are summarized in Table 1 below.

[Preparation of adhesive composition]
A (meth)acrylic polymer solution, a cross-linking agent, and a silane coupling agent were mixed so as to have the composition shown in Table 2 below to obtain solvent-type adhesive compositions P1 to P11. In addition, the content rate of a polymer, a crosslinking agent, and a silane coupling agent is a solid content conversion value.

[Preparation of optical laminate]
(Example 1)
After applying the prepared pressure-sensitive adhesive composition P1 on the release-treated surface of a release film (manufactured by Mitsubishi Plastics, MRF #38) with a fountain coater, it was dried for 2 minutes in an air circulation type constant temperature oven set at 155 ° C. , to form a layer (20 μm thick) of the adhesive composition. Separately, a PET film (thickness: 75 μm) having a modified surface that had been corona-treated in air (irradiation energy amount: 0.3 J/cm ² ) was prepared as an optical substrate. The layer of the pressure-sensitive adhesive composition formed above was attached to the modified surface of the prepared PET film to prepare an optical laminate including the pressure-sensitive adhesive layer and the optical substrate. The lamination was performed so that the portion not in contact with the adhesive layer was formed with a width of 50 mm or more from one side of the PET film.

(Examples 2 to 9)
Optical laminates of Examples 2 to 9 were obtained in the same manner as in Example 1, except that the adhesive compositions P2 to P9 were used instead of the adhesive composition P1.

(Comparative example 1)
Comparative Example 1 was prepared in the same manner as in Example 1, except that the adhesive composition P3 was used instead of the adhesive composition P1 and a PET film having no modified surface (same thickness) was used as the optical substrate. was obtained.

(Comparative example 2)
Comparative Example 2 was prepared in the same manner as in Example 1, except that the adhesive composition P10 was used instead of the adhesive composition P1 and a PET film having no modified surface (same thickness) was used as the optical substrate. was obtained.

(Comparative Example 3)
An optical laminate of Comparative Example 3 was obtained in the same manner as in Example 1, except that the adhesive composition P10 was used instead of the adhesive composition P1.

(Comparative Example 4)
An optical laminate of Comparative Example 4 was obtained in the same manner as in Example 1, except that the adhesive composition P11 was used instead of the adhesive composition P1.

[evaluation]
[Presence or absence of uneven distribution of Si agent (X)]
The optical laminates of Example 3 and Comparative Example 1 were evaluated by TOF-SIMS in combination with etching ions to determine whether the Si agent (X) was unevenly distributed in the pressure-sensitive adhesive layer. This evaluation method enables elemental analysis in the thickness direction of the pressure-sensitive adhesive layer. The TOF-SIMS evaluation conditions were as follows.
・Equipment: TRIFT-V made by ULVAC-PHI
・ Evaluation object: m / z = 45 corresponding to SiOH ⁺ ion
・Etching ions: Ar gas cluster ions ・Etching ion acceleration voltage: 10 kV
・Irradiated primary ions: Bi ₃ ²⁺
・Primary ion acceleration voltage: 30 kV
・Etching from the exposed surface of the adhesive layer toward the optical substrate

The evaluation results for each optical laminate of Example 3 and Comparative Example 1 are shown in FIGS. 5A and 5B, respectively. In the plots of FIGS. 5A and 5B, the horizontal axis represents the etching time (unit: seconds), and the vertical axis represents the normalized intensity of SiOH ⁺ ions normalized based on the intensity of C ₂ H ₃ ⁺ ions. As shown in FIG. 5A, in the optical laminate of Example 3, it was confirmed that the Si agent (X) was unevenly distributed in the region 21 near the interface with the PET film in the pressure-sensitive adhesive layer (shaded area). . In the plot of FIG. 5A, the sum of areas of SiOH ⁺ peaks in region 21 (accounting for 20% of the thickness of the adhesive layer) is 90% or more of the sum of areas of SiOH ⁺ peaks measurable in the adhesive layer. there were. On the other hand, as shown in FIG. 5B, in the optical laminate of Comparative Example 1, uneven distribution of the Si agent (X) was not observed. It was confirmed that uneven distribution of the Si agent (X) occurs due to the combination of the Si agent (X) and the modified surface of the optical substrate. In addition, in the plots of each figure, the intensity of SiOH ⁺ ions is observed to be relatively large even in the region within the PET film. This is probably because the intensity of C ₂ H ₃ ⁺ ions, which is the standard for normalization, is much smaller in the PET film than in the adhesive layer containing the (meth)acrylic polymer.

[800% modulus]
The 800% modulus of the adhesive layer was evaluated as follows. A pressure-sensitive adhesive layer formed on a release film was cut into a rectangular shape with a width of 30 mm and a length of 100 mm, and rolled into a cylindrical shape so as not to contain air bubbles, and this was used as a sample for measurement. Using a tensile tester, the stress at 800% elongation was obtained from the elongation-stress curve of the measurement sample measured under the conditions of an initial chuck distance of 10 mm and a tensile speed of 300 mm / min. /mm ² ) was calculated. Note that the elongation of 800% refers to a state in which the chuck-to-chuck distance is 90 mm. Autograph AG-IS manufactured by Shimadzu Corporation was used as a tensile tester. The evaluation was carried out at room temperature (23°C).

[High temperature adhesive strength]
The high temperature (80° C.) adhesive strength of the adhesive layer to the optical substrate was evaluated as follows. An additional PET film (thickness: 75 μm) that had undergone corona treatment in the same manner as above was attached to the optical laminates produced in each of the examples and comparative examples. Next, the laminated body obtained by bonding was cut into strips having a width of 25 mm and a length of 150 mm to obtain samples for measurement. The lamination is performed so that the adhesive layer of the optical laminate is in contact with the modified surface of the further PET film, and when the laminate is cut into strips, an adhesive layer is attached to one end of the laminate in the long side direction. A further PET film was carried out so that it had a first free edge (50 mm long) not in contact with the agent layer. During the bonding, a pressing roller having a mass of 2 kg defined by Japanese Industrial Standards (former Japanese Industrial Standards; JIS) Z0237:2009 was reciprocated once at a temperature of 25°C. The cutting is performed so that the portion of the optical base material provided when the optical laminate is not in contact with the adhesive layer is located at the other end in the long side direction as a second free end (50 mm in length). was carried out on After that, the sample for measurement left still for 30 minutes was set in a tensile tester with a constant temperature bath. The set was performed so that one chuck of the tester gripped the first free end and the other chuck gripped the second free end. Next, the environmental temperature of the testing machine and the test sample was controlled to the evaluation temperature (80°C). After standing still for 5 minutes after the environmental temperature reached the evaluation temperature, a peel test was performed by pulling both free ends in opposite directions at a test speed of 300 mm/min. After the start of the test, the initial measurement value (stress value) measured until the tensile distance (extended distance between chucks) from the initial state reaches 10 mm is ignored, and then the tensile distance from the initial state reaches 80 mm. The average value of the stress values measured until then was taken as the high-temperature adhesive strength.

Table 3 below shows the evaluation results for each optical layered body of Examples and Comparative Examples.

As shown in Table 3, in the optical layered bodies of Examples, the high-temperature adhesive strength could be improved while maintaining the cohesive strength of the adhesive layer. When the pressure-sensitive adhesive composition contained a silane coupling agent having an epoxy group at its terminal, the degree of improvement in high-temperature pressure-sensitive adhesive strength due to the surface modification of the PET film was small (Comparative Examples 2 and 3).

The optical laminate of the present invention can be used, for example, in image display devices.

REFERENCE SIGNS LIST 1 optical substrate 11 surface 12 modified surface 2 adhesive layer 21 region 3 interface 51 image forming layer 100, 110, 120 optical laminate 200 image display device

Claims (9)

comprising an optical substrate and a pressure-sensitive adhesive layer disposed on the surface of the optical substrate;
The pressure-sensitive adhesive layer contains a pressure-sensitive adhesive composition containing a silane coupling agent,
The silane coupling agent contains an isocyanuric ring and does not contain an isocyanate group,
The optical layered body, wherein the surface on which the pressure-sensitive adhesive layer is arranged is a modified surface that has been surface-modified by irradiation of energy. 2. The optical laminate according to claim 1, wherein the silane coupling agent is unevenly distributed in a region near the interface with the optical substrate in the pressure-sensitive adhesive layer. 3. The optical laminate according to claim 1, wherein the content of said silane coupling agent in said adhesive composition is 0.05% by weight or more and 1.0% by weight or less. The optical laminate according to any one of claims 1 to 3, wherein the optical substrate is made of resin. The optical laminate according to any one of claims 1 to 4, wherein the adhesive composition contains a (meth)acrylic polymer. 6. The optical laminate according to claim 5, wherein the (meth)acrylic polymer has a weight average molecular weight of 1,800,000 or more. The optical laminate according to any one of claims 1 to 6, wherein the surface modification by irradiation with energy is at least one selected from corona treatment, plasma treatment and ultraviolet treatment. an optical laminate according to any one of claims 1 to 7;
and an image forming layer. In the optical layered body according to any one of claims 1 to 7, a pressure-sensitive adhesive composition used by being arranged on the surface of the optical substrate,
containing a silane coupling agent,
The silane coupling agent contains an isocyanuric ring and does not contain an isocyanate group,
The pressure-sensitive adhesive composition, wherein the surface on which the pressure-sensitive adhesive composition is placed is a modified surface that has been surface-modified by irradiation of energy.

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