TW202311471A - Adhesive sheet, optical multilayer body and image display device - Google Patents

Abstract

The present invention provides an adhesive sheet having a haze of 0.1% or more, wherein if 10 evaluation regions each having an area of 1.5 [mu]m square are arbitrarily selected from a cross-sectional image of this adhesive sheet and an island region having a breadth of 100 nm or more is defined as a first domain, the number of evaluation regions in which the first domain is present is 5 or less. This adhesive sheet is capable of suppressing a dimensional change of an optical film that is contained in an optical multilayer body, while being suitable for securing durability and transparency.

Description

Adhesive sheet, optical laminate, and image display device

The invention relates to an adhesive sheet, an optical laminate and an image display device.

In recent years, image display devices represented by liquid crystal display devices and electroluminescent (EL) display devices (such as organic EL display devices and inorganic EL display devices) have been rapidly popularized. These various image display devices generally have a laminated structure of an image forming layer such as a liquid crystal layer, an EL light-emitting layer, and an optical layered body, and the optical layered body includes an optical film and an adhesive sheet. Adhesive sheets are mainly used to join the films contained in the optical laminate or to join the image forming layer and the optical laminate. Examples of optical films are polarizing plates, retardation films, and polarizing plates with retardation films in which a polarizing plate and a retardation film are integrated. Patent Documents 1 and 2 disclose an example of an optical layered body. prior art literature patent documents

Patent Document 1: Japanese Patent Laid-Open No. 2008-031214 Patent Document 2: Japanese Patent Laid-Open No. 2009-98665

The problem to be solved by the invention The size of the optical film changes excessively with the change of temperature, which will be the cause of light leakage or color unevenness of the image display device. Light leakage or color unevenness is especially likely to occur in a relatively large-sized image display device using a polarizing plate with a retardation film. In addition, image display devices whose bezels are designed to be narrower (bezel narrowed) continue to be popularized, so it is becoming more and more important to suppress dimensional changes. In order to suppress dimensional changes, it is conceivable to increase the modulus of elasticity of the adhesive sheet contained in the optical layered body. However, with only a high modulus of elasticity, the durability of the adhesive sheet may be lowered so that it cannot follow dimensional changes, and the transparency expected as an optical adhesive sheet may be impaired.

An object of the present invention is to provide an adhesive sheet which can suppress dimensional changes of an optical film contained in an optical laminate and is suitable for ensuring durability and transparency.

means to solve problems The present invention provides an adhesive sheet. Ten evaluation areas of 1.5 µm square are arbitrarily set on the cross-sectional image of the aforementioned adhesive sheet. When an island-shaped area with a short diameter of 100 nm or more is defined as the first domain, the aforementioned first domain exists. The number of the aforementioned evaluation areas in the 1 field is 5 or less; and The adhesive sheet has a haze of 0.1% or more.

In another aspect, the present invention provides an optical laminate comprising the above-mentioned adhesive sheet of the present invention and an optical film.

In another aspect, the present invention provides an image display device including the above-mentioned optical layered body of the present invention.

Invention effect According to the present invention, there can be provided an adhesive sheet capable of suppressing dimensional changes of an optical film contained in an optical laminate and suitable for ensuring durability and transparency.

Embodiments of the present invention will be described below with reference to the drawings. The present invention is not limited by the embodiments shown below.

In this specification, "(meth)acrylic acid" means acrylic acid and methacrylic acid. Moreover, "(meth)acrylate" means acrylate and methacrylate.

[adhesive sheet] An example of the adhesive sheet of this embodiment is shown in FIG. 1. Regarding the adhesive sheet 1 in Fig. 1, ten evaluation areas of 1.5 µm square are arbitrarily set on the cross-sectional image of the adhesive sheet 1, and when an island-shaped area with a short diameter of 100 nm or more is defined as the first area, there is a first area. The number of evaluation areas is 5 or less. Moreover, the adhesive sheet 1 has a haze of 0.1% or more.

In order to increase the modulus of elasticity of the adhesive sheet, for example, it is conceivable to blend additives into the adhesive composition for forming the adhesive sheet. Because the materials contained in the adhesive composition, typically the polymer that is the main component, and the additives are difficult to completely dissolve, so we believe that the haze of the adhesive sheet can be improved by blending the additives. According to the research of the inventors of the present invention, it has been found that if domains having a size larger than a certain level are formed in the adhesive sheet with increased haze, the durability and transparency of the adhesive sheet tend to decrease. We believe that the formation of domains may lead to: whitening of the adhesive sheet due to light scattering and reflection at the domain interface; and when the adhesive sheet is deformed by external force, there will be peeling progress at the domain interface, resulting in voids (voids), etc. . According to further studies, the adhesive sheet 1 having a haze of 0.1% or more and having the above-mentioned area can suppress the dimensional change of the optical film contained in the optical laminate and is suitable for ensuring durability and transparency.

In this specification, the haze of the adhesive sheet 1 is a value at a thickness of 75 µm, and can be measured in accordance with Japanese Industrial Standards (former Japanese Industrial Standards; JIS) K7136:1981.

The haze of the adhesive sheet 1 may be 0.2% or more. The upper limit of the haze is, for example, 1% or less, and may be 0.9% or less, 0.8% or less, 0.7% or less, 0.6% or less, 0.5% or less, less than 0.5%, 0.45% or less, less than 0.43%, 0.4% or less, and more Can be less than 0.37%.

In this specification, a field means an island-like region of a sea-island structure that the adhesive sheet 1 will have. Fields may contain substances derived from additives. In addition, the shortest path of the field can be defined as follows: Assume that there is an imaginary line segment passing through the center of gravity of the field and both ends of which are outside the field on the cross-sectional image. At this time, the shortest length of the imaginary line segment can be defined as the shortest path of the field. The evaluation areas set on the cross-sectional images should not overlap with each other. Cross-sectional images can be obtained, for example, by a transmission electron microscope (TEM). The magnification of the obtained cross-sectional image is, for example, 10,000 to 30,000 times.

The number of evaluation areas in which the first domain exists may be 4 or less, 3 or less, 2 or less, 1 or less, or may be 0 or less.

Regarding all the first areas observed in the above-mentioned 10 evaluation areas set in the cross-sectional image of the adhesive sheet 1, the shortest distance between adjacent first areas may be 300nm or more, may be 500nm or more, and may even be 800nm above. The shortest distance is large, which means that the above-mentioned areas in the adhesive sheet 1 have a low density. In addition, the distance between areas adjacent to each other can be defined as the distance between the outer peripheries.

When an island-shaped region having a short axis of 50 nm or more and less than 100 nm is defined as the second area, the number of evaluation areas in the second area is 10 or less among the above-mentioned 10 evaluation areas set in the cross-sectional image of the adhesive sheet 1 The number of regions may be 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, or even 10. According to the study of the inventors of the present invention, although the second field is not as good as the first field, it affects the durability and transparency of the adhesive sheet 1 .

When an island-shaped region having a short axis of 50 nm or more and less than 100 nm is defined as the second area, all the second areas observed in the above-mentioned 10 evaluation areas set in the cross-sectional image of the adhesive sheet 1, the adjacent second area The shortest distance between domains may be greater than 150 nm, may be greater than 175 nm, and may be greater than 200 nm.

When an island-shaped region with a short axis of 50 nm or more and less than 100 nm is defined as the second area, in all the second areas observed in the above-mentioned 10 evaluation areas set in the cross-sectional image of the adhesive sheet 1, the adjacent second area The ratio (ratio of the number of objects) of the second domain whose shortest distance between domains is 100 nm or more may be 50% or more, may be 60% or more, and may be 70% or more.

The state of the area in the adhesive sheet 1 can be evaluated, for example, by image analysis of the cross-sectional image. Various software such as ImageJ can be used for image analysis.

The state of the domains in the adhesive sheet 1 changes depending on the production conditions (including heating conditions described later) of the adhesive sheet 1 . Moreover, the state of the art will depend on the composition of the adhesive composition (I), the composition and characteristics (such as glass transition temperature) of the (meth)acrylic polymer (A), the type and blending of the crosslinking agent (B) The amount, as well as the type and blending amount of additives, etc. vary.

The thickness of the adhesive sheet 1 is, for example, 1-200 µm, 5-150 µm, 10-100 µm, 10-75 µm, 10-50 µm, 10-40 µm, 10-30 µm, or even 10-20 µm.

The storage elastic modulus G'(25°C) of the adhesive sheet 1 is, for example, 0.15 MPa or more, may be 0.16 MPa or more, 0.17 MPa or more, and may be 0.18 MPa or more. The upper limit of the storage elastic modulus G'(25°C) is, for example, 5 MPa or less, 3.0 MPa or less, 2.5 MPa or less, 2.0 MPa or less, 1.5 MPa or less, 1.0 MPa or less, 0.8 MPa or less, 0.6 MPa or less, or 0.5 MPa Below, it can be less than 0.5MPa. The adhesive sheet 1 having the storage elastic modulus G' within the above range is particularly suitable for suppressing the dimensional change of the optical film.

The storage elastic modulus (25° C.) of the adhesive sheet 1 can be evaluated by the following method. First, a measurement sample made of the material constituting the adhesive sheet 1 is prepared. The shape of the sample for measurement is disc-shaped. The diameter of the bottom surface of the sample for measurement is 8mm, and the thickness is 2mm. The sample for measurement may be a laminate obtained by laminating a plurality of adhesive sheets 1 and punched out into a disc shape. Next, dynamic viscoelasticity measurement was performed on the sample for measurement. For dynamic viscoelasticity measurement, for example, ARES-G2 manufactured by TA Instruments can be used. The storage elastic modulus G' of the adhesive sheet 1 at 25°C can be determined from the results of the dynamic viscoelasticity measurement. In addition, the conditions of dynamic viscoelasticity measurement are as follows. ・Measurement conditions Frequency: 1Hz Deformation Mode: Twist Measuring temperature: -70℃~150℃ Heating rate: 5°C/min

The gel fraction of the adhesive sheet 1 is, for example, 60% or more, may be 65% or more, and may be 70% or more. The upper limit of the gel fraction is, for example, 99% or less, may be 98% or less, and may be 95% or less. The adhesive sheet 1 having a gel fraction within the above range is particularly suitable for suppressing dimensional changes of optical films.

The gel fraction of the adhesive sheet 1 can be evaluated by the following method. First, about 0.2 g was scraped off from the adhesive sheet 1 to obtain small pieces. Next, the obtained small pieces were covered with stretched porous polytetrafluoroethylene membranes (NTF1122 manufactured by Nitto Denko, with an average pore diameter of 0.2 µm) and bound with kite strings to prepare test pieces. Next, the weight A of the obtained test piece was measured. Weight A is the total weight of small pieces of adhesive sheet, extended porous film and kite string. The total weight B of the extended porous membrane and the kite string used is measured in advance. Next, the test piece was dipped in a container with an inner volume of 50 mL filled with ethyl acetate, and left to stand at 23° C. for one week. After standing still, the test piece was taken out from the container and dried for 2 hours in a dryer set at 130° C., and then the weight C of the test piece was measured. From the measured weight A, weight B, and weight C, the gel fraction of the adhesive sheet 1 was calculated by gel fraction (weight %)=(C-B)/(A-B)×100(%).

The adhesive sheet 1 may be formed (I) from an adhesive composition (I) containing a (meth)acrylic polymer (A) as a main component and further containing an isocyanate crosslinking agent (B). However, the composition of the adhesive sheet 1 is not limited to the above example.

[Adhesive composition (I)] The adhesive composition (I) includes a (meth)acrylic polymer (A) and an isocyanate crosslinking agent (B). The (meth)acrylic polymer (A) is contained in the adhesive composition (I) as a main component. In other words, the adhesive composition (I) is an acrylic adhesive composition. The main component means the component with the largest content in the composition. The content rate of the main component is, for example, 50% by weight or more, may be 60% by weight or more, 70% by weight or more, 73% by weight or more, and may be 75% by weight or more.

((meth)acrylic polymer (A)) The (meth)acrylic polymer (A) preferably has, as a main unit, a structural unit derived from a (meth)acrylic monomer (A1) having an alkyl group having 1 to 30 carbon atoms in the side chain. The alkyl group may be linear or branched. A (meth)acrylic-type polymer (A) may have 1 type, or 2 or more types of structural units derived from a (meth)acrylic-type monomer (A1). Examples of (meth)acrylic monomers (A1) are: methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, secondary butyl (meth)acrylate, Tertiary butyl (meth)acrylate, isobutyl (meth)acrylate, n-pentyl (meth)acrylate, isopentyl (meth)acrylate, n-hexyl (meth)acrylate, (meth)acrylic acid Isohexyl, isoheptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)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), (meth)acrylate ) n-tridecyl acrylate and n-tetradecyl (meth)acrylate. In this specification, the "main unit" means, for example, a unit accounting for more than 50% by weight, preferably more than 60% by weight, more preferably more than 70% by weight of the total structural units of the polymer, and more preferably It is preferably a unit accounting for 80% by weight or more.

The (meth)acrylic-type polymer (A) may have the structural unit derived from the (meth)acrylic-type monomer (A1) which has a long-chain alkyl group in a side chain. An example of the monomer (A1) is n-dodecyl (meth)acrylate (lauryl (meth)acrylate). In this specification, "long-chain alkyl" means an alkyl group having 6 to 30 carbon atoms.

When the (meth)acrylic polymer (A) is a homopolymer, it may also have a (meth)acrylic monomer (A1) with a glass transition temperature (Tg) in the range of -70~-20°C constituent unit. An example of the monomer (A1) is n-butyl acrylate.

The (meth)acrylic polymer (A) may have structural units other than the structural unit derived from the (meth)acrylic monomer (A1). The constituent unit is derived from a monomer (A2) copolymerizable with a (meth)acrylic monomer (A1). The (meth)acrylic polymer (A) may have 1 type, or 2 or more types of this structural unit.

An example of the monomer (A2) is an aromatic ring-containing monomer. The aromatic ring-containing monomer may also be an aromatic ring-containing (meth)acrylic monomer. Examples of aromatic ring-containing monomers are: phenyl (meth)acrylate, phenoxyethyl (meth)acrylate, benzyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, oxidized Vinyl modified nonylphenol (meth)acrylate, hydroxyethylated β-naphthol (meth)acrylate and biphenyl (meth)acrylate. The content of the structural unit derived from the aromatic ring-containing monomer in the (meth)acrylic polymer (A) is, for example, 0 to 50% by weight, or 1 to 30% by weight, 5 to 25% by weight, 8 to 50% by weight. 20% by weight, 10-18% by weight, 11-17% by weight, more preferably 12-16% by weight. The (meth)acrylic polymer (A) has constituent units derived from aromatic ring-containing monomers, which can help improve the (meth)acrylic polymer (A) and crosslinking agent (B) and their self-polymerization compatibility of matter.

Another example of the monomer (A2) is a hydroxyl group-containing monomer. The hydroxyl group-containing monomer may also be a hydroxyl group-containing (meth)acrylic monomer. Examples of hydroxyl-containing monomers are: 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate hydroxyalkyl (meth)acrylate and (4-hydroxy Methylcyclohexyl)-methacrylate. In addition, hydroxyl groups can react with various crosslinking agents. From the viewpoint of improving the uniformity of the formed crosslinked structure, the content of the structural unit derived from the hydroxyl group-containing monomer in the (meth)acrylic polymer (A) may be 1% by weight or less, or may be 0.5% by weight. % by weight or less, may be 0.1% by weight or less, or may be 0% by weight (this structural unit may not be included).

The monomer (A2) may also be a carboxyl group-containing monomer, an amine group-containing monomer, or an amide 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 and crotonic acid. Examples of amino group-containing monomers include N,N-dimethylaminoethyl (meth)acrylate and N,N-dimethylaminopropyl (meth)acrylate. Examples of amide-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(methyl)acrylamide ) acrylamide, N-methylol-N-propane(meth)acrylamide, aminomethyl(meth)acrylamide, aminoethyl(meth)acrylamide, mercaptomethyl(methyl)acrylamide ) acrylamide and mercaptoethyl (meth)acrylamide and other acrylamide-based monomers; N-acryl heterocyclic monomers such as (meth)acrylpyrrolidine; body etc. When the (meth)acrylic polymer (A) has a structural unit derived from a carboxyl group-containing monomer, especially acrylic acid, for example, the self-polymerization of the isocyanate-based crosslinking agent (B) can be improved. Improving the self-polymerization of the cross-linking agent (B) contributes particularly to the suppression of peeling of the adhesive sheet in a humidified environment and the stabilization of the physical properties of the adhesive sheet in a system with a high content of the cross-linking agent (B).

Monomer (A2) may also be a polyfunctional monomer. Examples of polyfunctional 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, Neopentyl Glycol Di(meth)acrylate, Neopentyl tetra Alcohol tri(meth)acrylate, Dineopentaerythritol hexa(meth)acrylate, Trimethylolpropane tri(meth)acrylate, Tetramethylolmethane tri(meth)acrylate, (Meth ) polyfunctional acrylates such as allyl acrylate, vinyl (meth)acrylate, epoxy acrylate, polyester acrylate and urethane acrylate; and divinylbenzene. The multifunctional acrylate is preferably 1,6-hexanediol diacrylate and dipenteoerythritol hexa(meth)acrylate.

The total content of constituent units derived from carboxyl group-containing monomers, amine group-containing monomers, amide group-containing monomers, and polyfunctional monomers in the (meth)acrylic polymer (A) is preferably 20% by weight or less , more preferably 10% by weight or less, more preferably 8% by weight or less. When the (meth)acryl-type polymer (A) has this structural unit, the total content rate may be 0.01 weight% or more, for example, and may be 0.05 weight% or more. The (meth)acrylic polymer (A) may not contain a structural unit derived from a polyfunctional monomer.

Examples of other monomers (A2) are: 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, methoxytriethylene glycol (meth)acrylate, (methoxyethyl) Base) 3-methoxypropyl acrylate, 3-ethoxypropyl (meth)acrylate, 4-methoxybutyl (meth)acrylate and 4-ethoxybutyl (meth)acrylate, etc. (meth) Alkoxyalkyl acrylate; Epoxy-containing monomers such as (meth)glycidyl acrylate and methylglycidyl (meth)acrylate; sulfonic acid-containing monomers such as sodium vinyl sulfonate; Phosphate-containing monomers; (meth)acrylates with alicyclic hydrocarbon groups such as cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate and isobornyl (meth)acrylate; vinyl acetate and Vinyl esters such as vinyl propionate; Aromatic vinyl compounds such as styrene and vinyltoluene; Olefins or dienes such as ethylene, propylene, butadiene, isoprene and isobutylene; Vinyl alkyl ethers, etc. vinyl ethers; and vinyl chloride.

The total content of the constituent units derived from the other monomer (A2) in the (meth)acrylic polymer (A) is, for example, 30% by weight or less, may be 10% by weight or less, and is preferably 0% by weight ( does not contain this constituent unit).

The (meth)acrylic polymer (A) can be formed by polymerizing the above-mentioned 1 type or 2 or more types of monomers by a well-known method. It is also possible to polymerize monomers and partial polymers of monomers. Polymerization can be implemented by, for example, solution polymerization, emulsion polymerization, bulk polymerization, thermal polymerization, or active energy ray polymerization. Since an adhesive sheet with excellent optical transparency can be formed, solution polymerization and active energy ray polymerization are preferable. Polymerization should be carried out by avoiding contact of monomer and/or part of the polymer with oxygen. Therefore, for example, polymerization in an inert gas environment such as nitrogen, or polymerization in a state where oxygen is blocked by a resin film or the like can be used. The formed (meth)acrylic polymer (A) may be any form of a random copolymer, a block copolymer, a graft copolymer, etc.

The polymerization system for forming the (meth)acrylic polymer (A) may also contain one or two or more polymerization initiators. The type of polymerization initiator can be selected according to the polymerization reaction, for example, it can also be a thermal polymerization initiator or a photopolymerization initiator.

Solvents used in solution polymerization are, for example: 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; cyclohexane and methylcyclohexane Alicyclic hydrocarbons such as methyl ethyl ketone, methyl isobutyl ketone and other ketones. However, the solvent is not limited to the above examples. The solvent may be a mixed solvent of two or more solvents.

The polymerization initiator used for the solution polymerization is, for example, an azo-type polymerization initiator, a peroxide-type polymerization initiator, or a redox-type polymerization initiator. Peroxide-based polymerization initiators are, for example, dibenzoyl peroxide and tertiary butyl peroxymaleate. Among them, the azo-based polymerization initiator disclosed in Japanese Patent Application Laid-Open No. 2002-69411 is preferred. The azo-based polymerization initiator is, for example, 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis-2-methylbutyronitrile, 2,2'-azobis(2 -dimethylpropionate), 4,4'-azobis-4-cyanovaleric acid. However, the polymerization initiator is not limited to the above examples. The usage-amount of an azo type polymerization initiator is 0.05-0.5 weight part with respect to 100 weight part of total monomers, for example, and may be 0.1-0.3 weight part.

The active energy rays used for active energy ray polymerization are, for example, alpha rays, beta rays, gamma rays, neutron rays, ionizing radiation rays such as electron beams, and ultraviolet rays. The active energy rays are preferably ultraviolet rays. Polymerization by ultraviolet irradiation is also called photopolymerization. The polymerization system of active energy ray polymerization typically includes a photopolymerization initiator. The polymerization conditions of the active energy polymerization are not limited as long as the (meth)acrylic polymer (A) can be formed.

系光聚合引發劑。惟，光聚合引發劑不受上述例所限。The photopolymerization initiator is, for example, a benzoin ether photopolymerization initiator, an acetophenone photopolymerization initiator, an α-ketol alcohol photopolymerization initiator, an aromatic sulfonyl chloride photopolymerization initiator, a photoactive oxime Photopolymerization initiator, benzoin photopolymerization initiator, benzyl photopolymerization initiator, benzophenone photopolymerization initiator, ketal photopolymerization initiator, 9-oxosulfur

Department of photopolymerization initiator. However, the photopolymerization initiator is not limited to the above examples.

系光聚合引發劑例如為：9-氧硫𠮿

、2-氯9-氧硫𠮿

、2-甲基9-氧硫𠮿

、2,4-二甲基9-氧硫𠮿

、異丙基9-氧硫𠮿

、2,4-二異丙基9-氧硫𠮿

、十二烷基9-氧硫𠮿

。Benzoin ether-based photopolymerization initiators are, for example: benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dimethoxy Base-1,2-diphenylethan-1-one, anisole methyl ether. Acetophenone-based photopolymerization initiators are, for example: 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl phenyl ketone, 4 -Phenoxydichloroacetophenone, 4-(tertiary butyl)dichloroacetophenone. The α-ketol-based photopolymerization initiators include, for example, 2-methyl-2-hydroxypropiophenone and 1-[4-(2-hydroxyethyl)benzene]-2-methylpropan-1-one. The aromatic sulfonyl chloride photopolymerization initiator is, for example, 2-naphthalenesulfonyl chloride. The photoactive oxime-based photopolymerization initiator is, for example, 1-benzene-1,1-propanedione-2-(o-ethoxycarbonyl)-oxime. The benzoin-based photopolymerization initiator is, for example, benzoin. The benzyl group photopolymerization initiator is, for example, benzyl group. Benzophenone-based photopolymerization initiators are, for example, diphenyl ketone, benzoylbenzoic acid, 3,3'-dimethyl-4-methoxydiphenyl ketone, polyvinyl diphenyl ketone, α - Hydroxycyclohexyl phenyl ketone. The ketal photopolymerization initiator is, for example, benzyl dimethyl ketal. 9-oxosulfur

A photopolymerization initiator such as: 9-oxosulfur 𠮿

, 2-Chloro9-oxosulfur 𠮿

, 2-Methyl 9-oxosulfur 𠮿

, 2,4-Dimethyl 9-oxosulfur 𠮿

, Isopropyl 9-oxosulfur

, 2,4-Diisopropyl 9-oxosulfur 𠮿

, dodecyl 9-oxosulfur 𠮿

.

The usage-amount of a photoinitiator is 0.01-1 weight part with respect to 100 weight part of total monomers, for example, and may be 0.05-0.5 weight part.

The weight average molecular weight (Mw) of the (meth)acrylic polymer (A) is, for example, 1 million to 2.8 million. From the viewpoint of durability and heat resistance of the adhesive sheet, it may be 1.2 million or more, and may be More than 1.4 million. The weight average molecular weight (Mw) of the polymer and oligomer in this specification is the value (polystyrene conversion) measured by GPC (gel permeation chromatography; Gel Permeation Chromatography).

The content of the (meth)acrylic polymer (A) in the adhesive composition (I) is, for example, 50% by weight or more, 60% by weight or more, 70% by weight or more in terms of solid content. It may be 80% by weight or more. The upper limit of the content rate is, for example, 99% by weight or less, may be 97% by weight or less, 95% by weight or less, 93% by weight or less, and may be 90% by weight or less.

(Isocyanate-based crosslinking agent (B)) The isocyanate-based crosslinking agent (B) is one of the additives added to the adhesive composition. The crosslinking agent (B) contains an isocyanate group as a crosslinking reactive group. The crosslinking agent (B) is typically a polyfunctional crosslinking agent having two or more crosslinking reactive groups per molecule. The crosslinking agent (B) may be a trifunctional or more crosslinking agent having three or more crosslinking reactive groups per molecule. The upper limit of the number of crosslinking reactive groups per molecule is, for example, 5.

The isocyanate-based crosslinking agent (B) may be an aromatic isocyanate compound, an alicyclic isocyanate compound, or an aliphatic isocyanate compound.

Examples of aromatic isocyanate compounds that can be used in the crosslinking agent (B) are: phenylene diisocyanate, 2,4-cresyl diisocyanate, 2,6-cresyl diisocyanate, 2,2 '-Diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-toluidine diisocyanate, 4,4'-diphenyl ether diisocyanate, 4,4'-diphenyl diisocyanate Isocyanate, 1,5-naphthalene diisocyanate, stubble diisocyanate.

Examples of alicyclic isocyanate compounds that can be used in the crosslinking agent (B) are: 1,3-cyclopentene diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, isofor Ketone diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated stubble diisocyanate, hydrogenated cresyl diisocyanate and hydrogenated tetramethyl stubble diisocyanate.

Examples of aliphatic isocyanate compounds that can be used in the crosslinking agent (B) are: trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene 1,3-butylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate and 2,4,4-trimethylhexamethylene diisocyanate.

The crosslinking agent (B) may also be a derivative of the above-mentioned isocyanate compound. Examples of derivatives are: polymers (dimers, trimers, pentamers, etc.), adducts obtained by addition to polyhydric alcohols such as trimethylolpropane, urea modified products, biscondensed Modified urea, modified allophanate, modified isocyanate, modified carbodiimide, and polyether polyol, polyester polyol, acrylic polyol, polybutadiene polyol, poly Urethane prepolymer obtained from isoprene polyol, etc.

The crosslinking agent (B) is preferably an aromatic isocyanate compound and its derivatives, more preferably toluene diisocyanate and its derivatives (in other words, a toluene diisocyanate (TDI) crosslinking agent). Compared with extended diisocyanate and its derivatives (in other words, extended diisocyanate-based (XDI-based) cross-linking agents), TDI-based cross-linking agents have better reaction uniformity. An example of a TDI-based crosslinking agent is an adduct of toluene diisocyanate and a polyfunctional alcohol, and a more specific example is a trimethylolpropane/toluene diisocyanate trimer adduct.

A commercially available thing can be used for a crosslinking agent (B). Examples of commercially available products are: Millionate MT, Millionate MTL, Millionate MR-200, Millionate MR-400, CORONATE L, CORONATE HL, and CORONATE HX (the above are manufactured by Tosoh: all are trade names), and TAKENATE D-102, TAKENATE D-103, TAKENATE D-110N, TAKENATE D-120N, TAKENATE D-140N, TAKENATE D-160N, TAKENATE D-165N, TAKENATE D-170HN, TAKENATE D-178N, TAKENATE 500 and TAKENATE 600 (the above are manufactured by Mitsui Chemicals ; are trade names). As the crosslinking agent (B), CORONATE L, TAKENATE D-102, and TAKENATE D-103 (all trimethylolpropane/cresyl diisocyanate trimer adducts) can be used suitably.

In the adhesive composition (I), the blending amount of the crosslinking agent (B) is, for example, 1.5 parts by weight or more, or 2 parts by weight or more, based on 100 parts by weight of the (meth)acrylic polymer (A) , It can be more than 2.5 parts by weight. The upper limit of the blending amount is, for example, 25 parts by weight or less, may be 20 parts by weight or less, 15 parts by weight or less, 12 parts by weight or less, 10 parts by weight or less, 7 parts by weight or less, 5 parts by weight or less, and may be 4 parts by weight or less. servings or less.

The adhesive composition (I) may also contain one or more crosslinking agents (B).

When the adhesive sheet 1 is formed from an adhesive composition containing a crosslinking agent (B), the polymer of the crosslinking agent (B) may be contained in the first and/or second fields. Examples of polymers are self-polymers of the crosslinking agent (B).

Assuming that there is a self-polymer (C) of an isocyanate-based crosslinking agent (B), the distance Ra of the Hansen solubility parameter (HSP) between the (meth)acrylic polymer (A) and the self-polymer (C) It can also be 15 or less. The isocyanate-based crosslinking agents (B) may react with each other to form a self-polymer of the crosslinking agent (B) by the heat at the time of forming the adhesive sheet. Forming from the polymer increases the cohesive force of the adhesive sheet, thereby contributing to the formation of an adhesive sheet that suppresses dimensional changes of the optical film. However, we think that when the compatibility between the (meth)acrylic polymer (A) and the self-polymer is low, self-polymer-rich independent domains tend to be generated inside the adhesive sheet. According to the study of the inventors of the present invention, a distance Ra of 15 or less can contribute to the formation of the first domain and/or the second domain in the above state.

The distance Ra may be 14.5 or less, 14 or less, 13.5 or less, 13 or less, 12.5 or less, and may be 12 or less. The lower limit of the distance Ra is, for example, 6 or more.

Hansen Solubility Parameter (HSP) refers to the solubility parameter introduced by Hildebrand, which is divided into three components: dispersion term D, polarization term δP, and hydrogen bond term δH. δD represents energy derived from the dispersion force between molecules. δP represents energy derived from polar force between molecules. δH represents the energy derived from the hydrogen bonding force between molecules. The unit of each component is usually MPa ^1/2 . With the above three components, a point (vector) in the 3-dimensional space known as Hansen space is determined. The distance Ra is the point ( _{DA, PA, H A) corresponding to the (meth)acrylic polymer (A) and the point (D C , PC} , H _C ) corresponding to the polymer ( _C ) in the _above space The distance between can be calculated by the formula: {4×(δD _A -δD _B ) ² +(δP _A -δP _B ) ² +(δH _A -δH _B ) ² } ^1/2 . The details of Hansen Solubility Parameters are disclosed in "Hansen Solubility Parameters; A Users Handbook (CRC Press, 2007)". δD, δP, and δH of the polymer can be determined by calculation based on the constituent units of the polymer and the content of the units in the polymer, using known software such as HSPiP (version 5), for example. More specifically, the δD, δP, and δH of each constituent unit can be calculated individually, and the calculated δD, δP, and δH can be weighted according to the content of the unit to obtain a weighted average, and the weighted average can be used as the δD, δH, and δH of the polymer. δP and δH. However, the calculation was carried out by setting the temperature at 23°C. In addition, the calculated values of δD, δP, and δH may vary slightly depending on the software used. However, the magnitude of the difference is usually negligible when calculating Ra. With regard to crosslinkers, Hansen solubility parameters are calculated only for those formed from polymers.

The self-polymer (C) assumed in the calculation of the distance Ra is a single polymer composed of structural units derived from the isocyanate-based crosslinking agent (B). However, the self-polymer of the crosslinking agent (B) actually contained in the adhesive sheet formed of the adhesive composition (I) may contain structural units other than those derived from the crosslinking agent (B).

((meth)acrylic oligomer) The adhesive composition (I) may further include a (meth)acrylic oligomer (D).

The (meth)acrylic oligomer (D) may have the same composition as the (meth)acrylic polymer (A) above except that the weight average molecular weight (Mw) differs. The weight average molecular weight (Mw) of a (meth)acryl-type oligomer (D) is 1000 or more, for example, 2000 or more, 3000 or more, and 4000 or more. The upper limit of the weight average molecular weight (Mw) of a (meth)acrylic oligomer is 30000 or less, for example, 15000 or less, 10000 or less, and 7000 or less.

The (meth)acrylic oligomer (D) has, for example, one or more constituent units derived from the following monomers: methyl (meth)acrylate, ethyl (meth)acrylate, (meth)acrylate Propyl acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, secondary butyl (meth)acrylate, tertiary butyl (meth)acrylate, Amyl (meth)acrylate, Isoamyl (meth)acrylate, Hexyl (meth)acrylate, 2-Ethylhexyl (meth)acrylate, Heptyl (meth)acrylate, (Meth)acrylic acid Octyl, isooctyl (meth)acrylate, nonyl (meth)acrylate, isononyl (meth)acrylate, decyl (meth)acrylate, isodecyl (meth)acrylate, (meth) Alkyl (meth)acrylates such as undecyl acrylate and dodecyl (meth)acrylate; cyclohexyl (meth)acrylate, isobornyl (meth)acrylate and dicyclopentanyl (meth)acrylate Esters of (meth)acrylic acid and alicyclic alcohols such as esters; (meth)acrylates containing aromatic rings such as phenyl (meth)acrylate and benzyl (meth)acrylate; and alcohols derived from terpene compounds The resulting (meth)acrylate.

The (meth)acrylic oligomer (D) preferably has a structural unit derived from a (meth)acrylic monomer having a bulky structure. In this case, the adhesion of the adhesive sheet can be further improved. Examples of the acrylic monomers are: (meth)acrylic acid alkyl esters with branched alkyl groups such as isobutyl (meth)acrylate and tertiary butyl (meth)acrylate; Esters of (meth)acrylic acid and alicyclic alcohols such as cyclohexyl acrylate, isobornyl (meth)acrylate and dicyclopentanyl (meth)acrylate; phenyl (meth)acrylate and (meth)acrylic acid Aromatic ring-containing (meth)acrylate such as benzyl ester. The monomer preferably has a cyclic structure, and preferably has two or more cyclic structures. In addition, when the (meth)acrylic oligomer (D) is polymerized and/or when ultraviolet radiation is irradiated when the adhesive sheet is formed, the above-mentioned monomer is less likely to inhibit the progress of polymerization and/or formation. It is preferable not to have an unsaturated bond, for example, an alkyl (meth)acrylate having an alkyl group with a branched chain structure, an ester of (meth)acrylic acid and an alicyclic alcohol can be used.

Specific examples of (meth)acrylic oligomers (D) are: copolymers of butyl acrylate, methyl acrylate and acrylic acid, copolymers of cyclohexyl methacrylate and isobutyl methacrylate, methacrylic acid Copolymer of cyclohexyl methacrylate and isobornyl methacrylate, copolymer of cyclohexyl methacrylate and acrylmorphin, copolymer of cyclohexyl methacrylate and diethylacrylamide, 1-acrylic acid Copolymer of adamantyl ester and methyl methacrylate, copolymer of dicyclopentyl methacrylate and isobornyl methacrylate, selected from dicyclopentyl methacrylate, cyclohexyl methacrylate, methyl Copolymer of isocamyl acrylate, isocamyl acrylate, and cyclopentyl methacrylate with methyl methacrylate, homopolymer of dicyclopentyl acrylate, 1-adamantyl methacrylate Homopolymer of ester and homopolymer of 1-adamantyl acrylate.

The polymerization method of the above-mentioned (meth)acrylic-type polymer (A) can be used for the polymerization of a (meth)acrylic-type oligomer (D).

When the adhesive composition (I) contains the (meth)acrylic oligomer (D), its compounding amount is, for example, 70 parts by weight or less with respect to 100 parts by weight of the (meth)acrylic polymer (A), It may be 50 weight part or less, and may be 40 weight part or less. The lower limit of the compounding quantity is 1 weight part or more with respect to 100 weight part of (meth)acryl-type polymers (A), For example, 2 weight part or more may be sufficient as 3 weight part or more. The adhesive composition (I) may not contain the (meth)acrylic oligomer (D).

(additive) The adhesive composition (I) may also contain other additives. Examples of additives are: cross-linking agents other than isocyanate-based cross-linking agents (B), silane coupling agents, colorants such as pigments and dyes, surfactants, plasticizers, tackifiers, surface lubricants, leveling agents, Heavy industry enhancer, softener, antioxidant, antiaging agent, light stabilizer, ultraviolet absorber, polymerization inhibitor, antistatic agent (alkali metal salt of ionic compound, ionic liquid, ionic solid, etc.), inorganic filler, Powders, granules, and foils of organic fillers, metal powders, etc. The additive can be blended in the range of, for example, 10 parts by weight or less, preferably 5 parts by weight or less, more preferably 1 part by weight or less, with respect to 100 parts by weight of the (meth)acrylic polymer (A).

Examples of crosslinking agents other than the isocyanate crosslinking agent (B) include peroxide crosslinking agents, epoxy crosslinking agents, imine crosslinking agents, and polyfunctional metal chelate compounds. When the adhesive composition (I) contains a cross-linking agent other than the isocyanate-based cross-linking agent (B), the total blending amount is preferably 0.1 to 100 parts by weight of the (meth)acrylic polymer (A). 5 parts by weight, preferably 0.1-3 parts by weight, 0.1-2 parts by weight and 0.1-1 parts by weight. The adhesive composition (I) may not contain a crosslinking agent other than the isocyanate crosslinking agent (B), for example, may not contain an epoxy crosslinking agent.

Examples of silane coupling agents are: 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane Silane coupling agents containing epoxy groups such as silane and 2-(3-4-epoxycyclohexyl)ethyltrimethoxysilane; 3-aminopropyltrimethoxysilane, N-2-(aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylene)propylamine and N-phenyl-γ-aminopropyltrimethoxy Amino-containing silane coupling agents such as silane; 3-acryloxypropyltrimethoxysilane and 3-methacryloxypropyltriethoxysilane and other (meth)acrylyl-containing silane coupling agents agent; and silane coupling agent containing isocyanate group such as 3-isocyanate propyl triethoxysilane.

When the adhesive composition (I) contains a silane coupling agent, its compounding amount is, for example, 5 parts by weight or less, or 3 parts by weight or less, 1 It is not more than 0.5 parts by weight, not more than 0.2 parts by weight, not more than 0.1 parts by weight, and more preferably not more than 0.05 parts by weight. The adhesive composition (I) may also not contain a silane coupling agent.

The type of the adhesive composition (I) is, for example, latex type, solvent type (solution type), active energy ray (photocurable type), heat-melt type (hot-melt type), and the like. The adhesive composition (I) may be a solvent type from the viewpoint of being able to form an adhesive sheet more excellent in durability. The solvent-based adhesive composition (I) may not contain photocuring agents such as ultraviolet curing agents.

The adhesive sheet 1 can be used for optical applications, for example. The adhesive sheet 1 can also be used for an optical laminate and/or an image display device. The adhesive sheet 1 is suitable for use in, for example, an image display device with a narrower frame or an image display device with a larger screen size, especially for an image display device that requires suppression of dimensional changes for an optical film. By using it in such an image display device, for example, peeling of a film contained in an optical layered body can be suppressed.

[Manufacturing method of adhesive sheet] The adhesive sheet 1 can be formed by the manufacturing method of this embodiment demonstrated below, for example. However, the adhesive sheet 1 can also be formed by other manufacturing methods.

The production method of this embodiment includes the following steps: heating the coating film of the adhesive composition (I) to form the adhesive sheet 1 from the coating film, the adhesive composition (I) comprising (meth)acrylic acid The polymer (A) further contains an isocyanate crosslinking agent (B) as a main component. Hereinafter, heating of the said coating film is described as main heating (main heating). In the actual heating, the heat of the adhesive composition (I) contained in the coating film is mainly used for crosslinking and hardening.

The conditions for main heating satisfy the following formula (1) or (2). However, x and y are the heating temperature (° C.) and time (seconds) for the actual heating, respectively. Formula (2) means that when the heating temperature x is higher than 120°C, the heating time y should be limited to a predetermined time. The heating temperature x can be specified as the highest temperature exposed to the coating film, for example, it can be specified as the set temperature of a heating device such as a heating oven used to heat the coating film (when there are multiple intervals with different set temperatures in the heating device Or when the set temperature will change with time, it is the highest set temperature for the coating film to be exposed in the heating device). The time y of heating may be defined as the time during which the coating film is exposed to a temperature higher than 120°C. When a heating device is used, for example, the time for the coating film to be placed in a space set at a temperature higher than 120°C or the time for the coating film to pass through a section set at a temperature higher than 120°C can be specified as time y. When there are a plurality of intervals set to a temperature higher than 120° C., the time y can be defined as the total time for passing through the intervals. When the set temperature changes with time, the time during which the set temperature is higher than 120° C. can be calculated as time y. The same applies to the preheating temperature p and time q described later. x≦120・・・(1) x＞120 and y≦-2.17x+365.83・・・(2)

According to the studies of the inventors of the present invention, the solubility of the isocyanate-based crosslinking agent (B) in a monomeric state becomes poor at high temperatures, and tends to gradually aggregate inside the coating film. Therefore, the higher the temperature x and the longer the time y, the easier it is for the independent domains to be formed on the adhesive sheet, and the size and density of the generated domains tend to increase. On the other hand, if the temperature x is below a certain level, self-polymerization of the crosslinking agents (B) will preferentially proceed to form oligomers such as dimers and trimers, thereby inhibiting aggregation. Main heating under the conditions satisfying the above formula (1) or (2) is suitable for suppressing aggregation of the crosslinking agent (B).

The lower limit of the temperature x is, for example, 80°C or higher, may be 85°C or higher, and may be 90°C or higher. The upper limit of the temperature x is, for example, 165°C or less, and may be 160°C or less. The upper limit of the temperature x under the condition of satisfying the formula (1) may be 115°C or lower, 110°C or lower, 105°C or lower, 100°C or lower, 95°C or lower, more preferably 90°C or lower. The temperature x of the formal heating can be kept constant after the formal heating, or can be changed during the formal heating.

The lower limit of time y is, for example, 10 seconds or longer, may be 20 seconds or longer, 30 seconds or longer, 35 seconds or longer, 40 seconds or longer, greater than 40 seconds, 45 seconds or longer, and may be 50 seconds or longer. The upper limit of time y is, for example, less than 300 seconds, may be less than 180 seconds, and may be less than 180 seconds. The upper limit of the time y under the condition of satisfying formula (2) may also be 100 seconds or less, 95 seconds or less, 90 seconds or less, 85 seconds or less, 80 seconds or less, 75 seconds or less, 70 seconds or less, 65 seconds or less, and more It can be less than 60 seconds.

The formal heating condition can also satisfy y≦-2.17x+345.83 when x>120. Compared with the heating satisfying formula (2), the heating time y satisfying the above formula is more limited.

The conditions of formal heating can satisfy y≦80 under the condition of x>120, and can satisfy y≦60.

The formal heating condition is under x≦120, y<180 can be satisfied, and y≦160, y≦140, y≦120, y≦110, y≦100, y<100, y≦95, and more can be satisfied y≦90.

The production method of this embodiment may further include the following steps: before the actual heating of the coating film of the adhesive composition (I), under the heating conditions of temperature p (° C.) and time q (seconds), The aforementioned coating film is subjected to preliminary heating. The preheating temperature p is lower than the formal heating temperature x. In the preheating, the drying of the coating film is mainly carried out, and the solvent is removed from the solvent-based adhesive composition (I). Removing the solvent can help to suppress the aggregation of the isocyanate-based crosslinking agent (B). In addition, preheating can help to suppress the melting of the isocyanate-based crosslinking agent (B), and at the same time, the reaction with the compound having a hydroxyl group, typically the reaction with water, progresses to a certain extent to generate a crosslinking agent ( B) Oligomers.

The formal heating temperature x(°C) and the preheating temperature p(°C) can also satisfy the formula: x-p≦55. x-p may be below 50°C, below 45°C, below 40°C, below 35°C, below 30°C, below 30°C, below 25°C, below 20°C, below 15°C, and may be below 10°C. The lower limit of x-p is higher than 0°C, may be 5°C or higher, and may be 10°C or higher. A small difference between the temperature x and the temperature p can help to suppress the shrinkage of the coating film due to a sudden change in temperature.

The temperature p is, for example, 50°C or higher and lower than 80°C. The lower limit of the temperature p may be 55°C or higher, 60°C or higher, 65°C or higher, and may be 70°C or higher. The upper limit of temperature p may be 75 degreeC or less. The preheating temperature p can be kept constant after the preheating, or can be changed during the preheating.

The time q is, for example, 5 seconds or more, may be 10 seconds or more, 15 seconds or more, 20 seconds or more, 25 seconds or more, 30 seconds or more, 35 seconds or more, 40 seconds or more, and may be 45 seconds or more. The upper limit of the time q is, for example, 180 seconds or less, may be 120 seconds or less, 115 seconds or less, or may be 110 seconds or less.

When the adhesive composition (I) is a solvent type, the time q can also be such that the solvent contained in the coating film becomes 30% or less, preferably 25% or less, more preferably 20% or less, relative to the content before preheating. The method of content is set.

When expressed as the ratio q/(q+y) of the preheating time to the sum of the preheating and main heating time, the time q can also satisfy 0.2≦q/(q+y)≦0.6. The lower limit of q/(q+y) may be 0.25 or more, and may be 0.3 or more. The upper limit of q/(q+y) may be 0.55 or less, 0.5 or less, 0.45 or less, and may be 0.4 or less.

The preheating may be performed after a predetermined time r has elapsed after the coating film is formed. Securing the time r between the formation of the coating film and the start of preheating contributes to the effective removal of the solvent contained in the coating film. The time r is, for example, 5 to 180 seconds, or 5 to 120 seconds, or 10 to 60 seconds. During the time r, the coated film is in a non-heated gas environment, for example in a gas environment at 20-30°C.

Preheating and formal heating can also be implemented continuously. To give a more specific example, a heating device can also be divided into a preheating zone and a formal heating zone, and in the state of independently setting the temperature x and p of each zone, the coating film is transferred from the preheating zone to the Continuous conveying in the formal heating section.

The coating film subjected to the above-mentioned heating can be formed, for example, by applying the adhesive composition (I) or a mixture of the adhesive composition (I) and a solvent to a base film. The base film is typically a resin film or a metal film. The base film may be a film with a release treatment on the coated surface (release film). As an example of a peeling film, the coated surface is peeled off with polysiloxane. In addition, the base film may be an optical film, and in this case, an optical laminate including an adhesive sheet and an optical film can be formed.

A known method can be used for coating on a base film. Coating can be performed by, for example, roll coating, touch roll coating, gravure coating, reverse coating, roll brush coating, spray coating, dip roll coating, rod coating, knife coat, air knife coating, curtain coating, etc. Coating, lip coating, and extrusion coating using a die coater or the like are performed.

Compositions and mixtures applied to substrate films preferably have a viscosity suitable for handling and coating.

[Optical laminate] An example of the optical layered body of this embodiment is shown in FIG. 2 . The optical laminate 10A in FIG. 2 includes an adhesive sheet 1 and an optical film 2 . The adhesive sheet 1 and the optical film 2 are laminated together. The optical layered body 10A can be used as an optical film with an adhesive sheet attached.

Examples of the optical film 2 are a polarizing plate, a retardation film, and a laminated film including a polarizing plate and/or a retardation film. However, the optical film 2 is not limited to the above examples. The optical film 2 may also include a glass film.

The polarizing plate includes polarizers. A polarizer protective film may also be bonded to at least one side of the polarizer. When bonding the polarizer and the polarizer protective film, any adhesive or adhesive can be used. The adhesive sheet 1 can also be used for bonding. The polarizer is typically a polyvinyl alcohol (PVA) film with iodine oriented by stretching in the air (dry stretching), boric acid underwater stretching, etc.

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

The retardation film can also be a λ/4 plate, a λ/2 plate, a retardation film for anti-reflection (for example, refer to paragraphs 0221, 0222, and 0228 of Japanese Patent Application Laid-Open No. 2012-133303), a retardation film for viewing angle compensation ( For example, refer to paragraphs 0225 and 0226 of Japanese Patent Application Laid-Open No. 2012-133303), and oblique orientation retardation film for viewing angle compensation (for example, refer to paragraph 0227 of Japanese Patent Application Laid-Open No. 2012-13303). The retardation film is not limited to the above examples as long as it has birefringence in the in-plane direction and/or in the thickness direction. There are also no restrictions on the retardation value, arrangement angle, 3-dimensional birefringence, single-layer or multi-layer of the retardation film. As the retardation film, known films can be used.

The thickness of the optical film 2 is, for example, 1-200 μm. The thickness of the optical film 2 used as a polarizer is, for example, 1 to 150 µm, and may be less than 100 µm, less than 75 µm, less than 50 µm, less than 20 µm, and even less than 15 µm. The lower limit of the thickness may be 10 µm or more, 20 µm or more, 50 µm or more, 75 µm or more, and may be 100 µm or more.

The optical film 2 may be a single layer or a laminated film composed of two or more layers. When the optical film 2 is a laminated film, the adhesive sheet 1 can also be used for joining the layers.

Another example of the optical layered body of this embodiment is shown in FIG. 3 . The optical laminate 10B in FIG. 3 has the following laminated structure: a release liner 3 , an adhesive sheet 1 and an optical film 2 are laminated in this order. The optical layered body 10B can be used as an optical film with an adhesive sheet by peeling off the release liner 3 .

The release liner 3 is typically a resin film. Examples of the resin constituting the release liner 3 are polyester such as polyethylene terephthalate (PET), polyolefin such as polyethylene and polypropylene, polycarbonate, acrylic, polystyrene, polyamide, and polyamide imine. The surface of the release liner 3 that is in contact with the adhesive sheet 1 can also be subjected to release treatment. The peeling treatment is, for example, treatment by polysiloxane. However, the release liner 3 is not limited to the above examples. When using the optical layered body 10B, the release liner 3 will be peeled, for example, when sticking to an image forming layer.

Another example of the optical layered body of this embodiment is shown in FIG. 4 . The optical laminate 10C in FIG. 4 has the following laminate structure: a release liner 3 , an adhesive sheet 1 , a retardation film 2A, an interlayer adhesive 4 and a polarizing plate 2B are laminated in sequence. The optical layered body 10C can be used after peeling the release liner 3, for example, by sticking to the image forming layer.

A well-known adhesive can be used for the interlayer adhesive 4. The adhesive sheet 1 can also be used for the interlayer adhesive 4 .

Another example of the optical layered body of this embodiment is shown in FIG. 5 . The optical laminate 10D in FIG. 5 has the following laminate structure: a release liner 3 , an adhesive sheet 1 , a retardation film 2A, an interlayer adhesive 4 , a polarizing plate 2B and a protective film 5 are laminated in sequence. The optical layered body 10D can be used after peeling off the release liner 3, for example, by sticking to the image forming layer.

The protective film 5 has the function of protecting the outermost optical film 2 (polarizer 2B) during distribution and storage of the optical laminate 10D and when the optical laminate 10D is incorporated into an image display device. In addition, in a state where an image display device is incorporated, the protective film 5 functioning as a window to the external space may also be used. The protective film 5 is typically a resin film. The resin constituting the protective film 5 is, for example, polyester such as PET, polyolefin such as polyethylene and polypropylene, acrylic, cycloolefin, polyimide, and polyamide, preferably polyester. However, the protective film 5 is not limited to the above examples. The protective film 5 may be a glass film or a laminated film including a glass film. Surface treatments such as anti-glare, anti-reflection, and anti-static can also be applied to the protective film 5 .

The protective film 5 can also be bonded to the optical film 2 by any adhesive. It can also be joined by the adhesive sheet 1 .

The optical layered body may have any configuration as long as it includes an adhesive sheet formed by the above-mentioned method for producing an adhesive sheet.

The optical layered body of this embodiment can be distributed and stored, for example, in the form of a winding body in which a tape-shaped optical layered body is wound, or in the form of a single sheet-shaped optical layered body.

Typically, the optical layered body of this embodiment can be used for an image display device. The image display device is, for example, an EL display such as a liquid crystal display, an organic EL display, or an inorganic EL display.

[image display device] An example of the image display device of this embodiment is shown in FIG. 6 . The image display device 11 of FIG. 6 has the following laminated structure: a substrate 7, an image forming layer (such as an organic EL layer or a liquid crystal layer) 6, an adhesive sheet 1, a retardation film 2A, an interlayer adhesive 4, and a polarizing plate are laminated in sequence. 2B and protective film 5. The image display device 11 has the optical laminates 10A, 10B, 10C, and 10D shown in FIGS. 2 to 5 (except for the release liner 3 ). The substrate 7 and the image forming layer 6 may have the same configuration as the substrate and image forming layer of a known image display device, respectively.

The image display device 11 in FIG. 6 can be an organic EL display or a liquid crystal display. However, the image display device 11 is not limited to this example. The image display device 11 can also be an electroluminescence (EL) display, a plasma display (PD), a field emission display (FED: Field Emission Display) and the like. The image display device 11 can also be used in home appliances, in-vehicle applications, public information display (PID) applications, and the like.

The image display device may have any configuration as long as it includes the adhesive sheet formed by the above-mentioned method for producing an adhesive sheet and/or the optical layered body formed by the above-mentioned method for producing an optical layered body.

Example Hereinafter, the present invention will be described in more detail using examples. The present invention is not limited by the Examples shown below.

First, evaluation methods of (meth)acrylic polymers and adhesive sheets produced in Examples and Comparative Examples will be shown.

[Weight average molecular weight (Mw)] The weight-average molecular weight (Mw) of the (meth)acrylic polymer was evaluated by GPC under the following conditions. ・Analyzer: Acquity APC manufactured by Waters ・Column: Made by Tosoh, G7000HXL+GMHXL+GMHXL ・Column temperature: 40°C ・Eluent: Tetrahydrofuran (acid added) ・Flow rate: 0.8mL/min ・Injection volume: 100µL ・Detector: Differential refractometer (RI) ・Standard sample: Polystyrene (PS) manufactured by Agilent

[distance Ra] The distance Ra is calculated by the above method. The soft system uses HSPiP (version 5).

[Storage elastic modulus G'(25℃)] The storage elastic modulus G'(25°C) of the adhesive sheet was evaluated by the above method. However, the sample for measurement was prepared by punching out a laminate obtained by laminating the produced adhesive sheets into a disc shape. For the dynamic viscoelasticity measurement of the measurement sample, ARES-G2 manufactured by TA Instruments was used.

[whitening] Based on the haze measurement of the adhesive sheet, the degree of whitening of the adhesive sheet was evaluated in the following manner. The smaller the haze, the smaller the degree of whitening can be judged. The haze of the adhesive sheet is measured in a 25° C. gas atmosphere using a haze meter HZ-V3 manufactured by Suga Test Instruments Co., Ltd., for example, in accordance with JIS K7136:1981. The measurement is the state of the adhesive sheet with 5 layers (the thickness of the adhesive sheet is 15 µm) or 3 layers (the thickness of the adhesive sheet is 25 µm) attached to the glass slide S012140 (thickness 1.3 mm) manufactured by Songnang Glass Industry Co., Ltd. (total The thickness is 75µm). Regarding the adhesive sheet of Example 21 with a thickness of 35 µm, the measured value V in the state where two layers were attached (total thickness 70 µm) was converted into a value equivalent to a total thickness of 75 µm using the formula: V×75/70. A: The measured haze is less than 0.37% B: The measured haze is more than 0.37% and less than 0.43% C: The measured haze is more than 0.43% and less than 0.50% D: The measured haze is above 0.50%

[Region status] The status of the region of the adhesive sheet is evaluated by the above-mentioned evaluation method on the cross-sectional image of the adhesive sheet. The acquisition of cross-sectional images was carried out by TEM (manufactured by Hitachi, HT7820; accelerating voltage 100 kV), and the magnification was set to 20,000 times. The sample for TEM is prepared in the following way: use RuO ₄ to apply heavy metal staining to the adhesive sheet of the evaluation object, and then use resin to embed it, and cut it into a thickness of about 100nm by ultrathin section method. The evaluation regions at 10 locations in the cross-sectional image were set so as not to overlap each other. Evaluation of status was performed by image analysis of cross-sectional images using ImageJ. Statuses 1 to 5 in the field to be evaluated and the evaluation criteria for each status are as follows.

(Status 1: the number of evaluation areas that exist in the 1st domain) A: The number of evaluation areas is 0 B: The number of evaluation areas is 1~2 C: The number of evaluation areas is 3~5 D: The number of evaluation areas is 6 or more

(Status 2: The shortest distance between adjacent first domains for all first domains) A: The shortest distance is above 300nm D: The shortest distance is less than 300nm

(Status 3: The shortest distance between adjacent second domains for all second domains) A: The shortest distance is above 200nm C: The shortest distance is more than 150nm and less than 200nm D: The shortest distance is less than 150nm

(Status 4: The number of evaluation areas where the number of second domains is 10 or less) A: The number of evaluation areas is 3 or more D: The number of evaluation areas is 1~2

(Status 5: Ratio of domains in which the shortest distance between adjacent second domains is 100nm or more in all second domains) A: more than 50% D: Less than 50%

[the humidification durability] The humidity durability of the adhesive sheet (corresponding to the accelerated test of durability) was evaluated by the following method. First, an adhesive sheet-attached circular polarizing plate was formed, which was equipped with each of the adhesive sheets produced in Examples and Comparative Examples on one exposed surface. Next, a circular polarizing plate was fixed on the surface of a glass plate (made by Corning, Eagle XG) through the above-mentioned adhesive sheet. The fixation of the circular polarizer is carried out in an air environment of 23°C and 50% RH. Then, after 15 minutes in an autoclave at 50°C and 5 atmospheres (absolute pressure), let it cool down to 23°C to make the circular polarizing plate stably bonded to the glass plate, then heat and humidify the gas at 60°C and 95%RH Placed in the environment for 500 hours. After standing, return to the atmosphere of 23°C and 50% RH, check with the naked eye whether the circular polarizing plate is peeled off from the glass plate or whether there is foaming between the glass plate and the circular polarizing plate, and evaluate the humidity durability as follows. A: No change in appearance such as foaming or peeling was observed. B: Slight individual peeling or foaming was observed at the edge, but practically within the range of no problem. C: Slight continuous peeling or foaming was observed at the end, but practically within the range of no problem. D: Significant peeling or foaming was observed at the edge, which was problematic for practical use.

A method of forming a circular polarizing plate with an adhesive sheet for evaluation of humidity durability is shown below.

＜Production of polarizing plate P1＞ (production of polarizer) A long strip of polyvinyl alcohol (PVA)-based resin film (manufactured by Kuraray, product name "PE3000", thickness 30µm) was uniaxially stretched in the longitudinal direction with a roll stretcher (total stretch ratio: 5.9 times), and the above resin Swelling, dyeing, cross-linking, washing and drying are performed on the film sequentially to produce a polarizer with a thickness of 12µm. In the swelling treatment, the above-mentioned resin film was stretched 2.2 times while being treated with pure water at 20°C. In the dyeing process, the above-mentioned resin film was stretched 1.4 times while being treated with a 30° C. aqueous solution containing iodine and potassium iodide at a weight ratio of 1:7. The concentration of iodine in the aqueous solution was adjusted so that the single transmittance of the manufactured polarizer could be 45.0%. The cross-linking treatment system adopts 2-stage treatment. In the first stage of cross-linking treatment, the above-mentioned resin film was stretched 1.2 times while treating with a 40° C. aqueous solution in which boric acid and potassium iodide were dissolved. In the aqueous solution used for the first-stage crosslinking treatment, the content of boric acid was 5.0% by weight, and the content of potassium iodide was 3.0% by weight. In the second stage of cross-linking treatment, the above-mentioned resin film was stretched 1.6 times while treating with a 65° C. aqueous solution in which boric acid and potassium iodide were dissolved. In the aqueous solution used for the second-stage crosslinking treatment, the content of boric acid was 4.3% by weight, and the content of potassium iodide was 5.0% by weight. A potassium iodide aqueous solution at 20°C is used for cleaning. In the aqueous solution used for the cleaning treatment, the content of potassium iodide was 2.6% by weight. The drying treatment is carried out under the drying conditions of 70° C. and 5 minutes.

(Production of Polarizer P1) A triacetyl cellulose (TAC) film (manufactured by Konica Minolta, product name "KC2UA", thickness 25 µm) was attached to each main surface of the polarizer prepared above through a polyvinyl alcohol-based adhesive. However, for the TAC film bonded to one main surface, a hard coat layer (thickness 7 µm) was formed on the main surface opposite to the polarizer side. In the above-mentioned manner, the polarizing plate P1 having the composition of protective layer with hard coat/polarizer/protective layer (no hard coat) was obtained.

＜Production of Retardation Film R1＞ (Production of the first retardation film) 26.2 parts by weight of isosorbide (ISB), 100.5 parts by weight of 9,9-[4-(2-hydroxyethoxy)phenyl] fennel (BHEPF), 1,4-cyclohexanedimethanol (1,4 -CHDM) 10.7 parts by weight, diphenyl carbonate (DPC) 105.1 parts by weight, and cesium carbonate (0.2% by weight aqueous solution) as a catalyst 0.591 parts by weight were put into the reaction vessel and dissolved under nitrogen atmosphere (about 15 minutes) . At this time, the temperature of the heat medium in the reaction container was set to 150° C., and stirring was performed as necessary. Next, the pressure in the reaction container was reduced to 13.3 kPa, and the temperature of the heat medium was raised to 190° C. within 1 hour. Phenol generated as the temperature of the heat medium rises is discharged to the outside of the reaction container (the same applies hereinafter). Next, after maintaining the temperature in the reaction container at 190° C. for 15 minutes, the pressure in the reaction container was changed to 6.67 kPa, and the temperature of the heat medium was raised to 230° C. within 15 minutes. When the stirring torque of the stirrer equipped in the reaction vessel was increased, the temperature of the heat medium was raised to 250° C. within 8 minutes, and the pressure in the reaction vessel was further reduced to 0.200 kPa or less. After the predetermined stirring torque is reached, the reaction is ended, and the generated reactant is extruded into water to pelletize it. In the above manner, a polycarbonate resin having a composition of BHEPF/ISB/1,4-CHDM=47.4 mol%/37.1 mol%/15.5 mol% was obtained. The glass transition temperature of the obtained polycarbonate resin was 136.6° C., and the reduced viscosity was 0.395 dL/g.

After drying the pellets of polycarbonate resin at 80°C for 5 hours in vacuum, use a single-screw extruder (manufactured by Isuzu Chemical Industries Co., Ltd., screw diameter 25mm, cylinder set temperature 220°C) ), T-die (width 200mm, set temperature 220°C), cooling roll (set temperature 120~130°C) and coiler film-making device to obtain a long strip of resin film with a thickness of 120µm. Next, the obtained resin film was stretched in the width direction at a stretching temperature of 137-139° C. and a stretching ratio of 2.5 times using a tenter stretcher to obtain a first retardation film.

(Production of the second retardation film) 20 parts by weight of the side chain type liquid crystal polymer (weight average molecular weight 5000) shown in the following chemical formula (I) (wherein, 65 and 35 are the mole % of each constituent unit) shows the polymerization of the nematic liquid crystal phase Liquid crystal (manufactured by BASF, trade name "PaliocolorLC242") 80 parts by weight and photopolymerization initiator (manufactured by Ciba Specialty Chemicals, trade name "IRGACURE 907") 5 parts by weight were dissolved in 200 parts by weight of cyclopentanone to prepare a liquid crystal Coating solution. Next, the prepared liquid crystal coating solution was applied to the surface of the substrate film, that is, a northylene-based resin film (manufactured by ZEON Japan, trade name "ZEONEX") with a bar coater, and then heated and dried at 80°C for 4 Minutes to align the liquid crystal contained in the coating film. Next, the coating film was cured by ultraviolet irradiation, and a liquid crystal solidified layer (thickness: 0.58 µm) was formed as a second retardation film on the base film. The in-plane retardation Re of the liquid crystal solidified layer to light with a wavelength of 550nm is 0nm, and the retardation Rth in the thickness direction is -71nm (nx=1.5326, ny=1.5326, nz=1.6550), and the liquid crystal solidified layer exhibits nz>nx= The refractive index characteristics of ny.

[chemical formula 1]

(Manufacturing of Retardation Film R1) The retardation film R1 was produced by bonding one side of the above-produced first retardation film and the liquid crystal solidified layer of the second retardation film through an adhesive.

＜Production of circular polarizing plate with adhesive sheet＞ (Production of interlayer adhesive) In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen inlet tube and a cooler, feed 79.9 parts by weight of butyl acrylate, 15 parts by weight of benzyl acrylate, 5 parts by weight of acrylic acid and 0.1 part by weight of 4-hydroxybutyl acrylate monomer mixture. Next, with respect to 100 parts by weight of the monomer mixture, 0.1 part by weight of 2,2'-azoisobutyronitrile and ethyl acetate were added together as a polymerization initiator, and nitrogen gas was introduced into the flask while stirring slowly to replace nitrogen in the flask. , The liquid temperature in the flask was kept at around 55° C. and the polymerization reaction was carried out for 7 hours. Next, ethyl acetate was added to the obtained reaction liquid to adjust to a solid content concentration of 30% by weight, thereby obtaining a solution of a (meth)acrylic polymer used as an interlayer adhesive. The weight average molecular weight of the obtained polymer was 2.2 million.

Next, in the obtained (meth)acrylic polymer solution, a trimethylolpropane/cresyl diisocyanate trimer adduct (manufactured by Tosoh, 0.5 part by weight of product name "CORONATE L", 0.1 part by weight of benzoyl peroxide as a peroxide crosslinking agent, silane coupling agent containing epoxy group (manufactured by Shin-Etsu Chemical Co., Ltd., product name "KBM-403") ) 0.2 parts by weight and 0.5 parts by weight of a polyether compound having a reactive silicon group (manufactured by Kaneka, Silyl SAT10) to obtain an adhesive composition PSA1 for an interlayer adhesive used to bond the polarizing plate P1 and retardation film R1.

(Manufacture of polarizing plate with interlayer adhesive layer) Apply the adhesive composition PSA1 prepared above on the release film treated with silicone on the peeling surface, that is, apply the adhesive composition PSA1 prepared above on the polyethylene terephthalate with a thickness of 38 μm The peeled surface of a diester (PET) film (manufactured by Mitsubishi Polyester Film, MRF38) was dried so that the layer thickness would be 12 µm, and then dried at 155°C for 1 minute to form an interlayer adhesive layer. Next, the formed interlayer adhesive layer was transferred to the protective layer (no hard coat layer) side of the polarizing plate P1 to obtain a polarizing plate with an interlayer adhesive layer.

(Production of circular polarizing plate with adhesive sheet) Each of the adhesive sheets produced in Examples and Comparative Examples was transferred from the release film and attached to the second retardation film side of the retardation film R1 (when making the second retardation film, the film used as the substrate film will be Vinyl resin film peeling off). Next, the above-prepared polarizer with an interlayer adhesive layer was attached to the first retardation film side of the retardation film R1 through the interlayer adhesive layer to obtain a circular polarizer with an adhesive sheet. The attachment of the retardation film R1 and the polarizing plate with the interlayer adhesive layer is based on the counterclockwise direction of the angle formed by the slow axis of the first retardation film and the absorption axis of the polarizer when viewed from the side of the first retardation film It is implemented in a 45-degree manner.

[Condensation trace (appearance)] Check with the naked eye whether there are traces of liquid droplets on the surface of the peeling film and coating film (adhesive sheet) after formal heating, and evaluate the traces of condensation that will occur during the manufacture of the adhesive sheet in the following manner. A: No trace of liquid droplet was observed. B: Although traces of liquid droplets were observed slightly, it was a practically no-problem level. C: Traces of liquid droplets are observed, and there is a problem in practical use.

[Extent of Survival] The content of residual monomer and residual solvent contained in the adhesive sheet formed on the release sheet was determined, and the degree of residual was evaluated in the following manner. In addition, ppm is based on weight. A: The content of residual monomer and the content of residual solvent are both less than the detection limit B: The total content of residual monomers and residual solvents is above the detection limit and below 50ppm C: The total content of residual monomer and residual solvent is greater than 50ppm and less than 100ppm D: The total content of residual monomer and residual solvent is greater than 100ppm

(Determination of residual monomers) Take about 0.1g of the adhesive sheet into a screw bottle, add 5mL of acetone and vibrate overnight. Then, filter the contents of the screw bottle with a membrane filter (average pore size 0.45 µm) and inject 1 µL of the obtained filtrate into a gas chromatograph (GC) to determine the content of residual monomers. The measurement conditions of GC are shown below. GC device: manufactured by Agilent Technologies, 6890N Column: Agilent Technologies, HP-1 (0.250mmφ×30m, df=1.0µm) Column temperature: After maintaining at 40°C for 1 minute, raise the temperature to 60°C (speed 5°C/min), then raise the temperature to 140°C (speed 10°C/min), then raise the temperature to 300°C (speed 20°C/min) , and hold at 300°C for 10 minutes Column flow: 2mL/min (He) Column pressure: constant flow mode (136kPa) Injection port temperature: 200°C Injection volume: 1µL Injection method: shunt (10:1) Detector: Flame Ionization Detector Hydrogen Energy Ionization Detector (FID) Detector temperature: 250°C

(Determination method of residual solvent) Take about 0.02g of the adhesive sheet and seal it into a 20mL headspace vial. Next, the vial sealed with the adhesive sheet was heated in a headspace sampler (HSS) at 150°C for 30 minutes, and 1 mL of the gas phase in the heated vial was injected into the GC to determine the residual solvent content. The conditions of HSS and the measurement conditions of GC are shown below. ・HSS conditions HSS device: manufactured by Agilent Technologies, G1888 Heating temperature: 150°C Heating time: 30 minutes Pressurization time: 0.20 minutes Loop fill time: 0.20 minutes Cycle balance time: 0.05 minutes Injection time: 0.50 minutes Sample cycle temperature: 160°C Transfer molding temperature: 200°C ・GC measurement conditions (residual solvent) GC device: manufactured by Agilent Technologies, 6890N Column: Agilent Technologies, HP-1 (0.250mmφ×30m, df=1.0µm) Column temperature: After maintaining at 40°C for 3 minutes, raise the temperature to 120°C (speed 10°C/min), then raise the temperature to 300°C (speed 20°C/min), and keep at 300°C for 10 minutes Column flow: 1mL/min (He) Column pressure: constant flow mode (81kPa) Injection port temperature: 250°C Injection volume: 1mL Injection method: diversion (20:1) Detector: FID Detector temperature: 250°C

[Comprehensive Evaluation] A comprehensive evaluation of the durability and transparency of the adhesive sheet is carried out in the following manner. A: The evaluation of humidification durability is A, and the evaluation of whitening is A~C. B: The evaluation of humidification durability is B, and the evaluation of whitening is A~C. C: The evaluation of humidification durability is C, and the evaluation of whitening is A~C. D: The evaluation of at least one of the humidification durability and whitening was D.

Next, the manufacturing method of each adhesive sheet of an Example and a comparative example is demonstrated.

The correspondence between the abbreviations or names shown in the following description and the compounds is as follows. BA: n-butyl acrylate BzA: benzyl acrylate AA: Acrylic HBA: 4-Hydroxybutyl Acrylate AIBN: 2,2'-Azobisisobutyronitrile C/L: Trimethylolpropane/cresyl diisocyanate trimer adduct (isocyanate-based crosslinking agent; manufactured by Tosoh, CORONATE L) TetradC: 1,3-bis(N,N-diecidylaminomethyl)cyclohexane (polyfunctional epoxy-based crosslinking agent; manufactured by MITSUBISHI GAS CHEMICAL, TetradC) KBM403: 3-glycidoxypropyltriethoxysilane (silane coupling agent; Shin-Etsu Chemical Co., Ltd., KBM403)

[Preparation of (meth)acrylic polymer (A)] (Synthesis Example 1) Into a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen inlet tube, and a cooler, 94.9 parts by weight of BA and 5.0 parts by weight of AA were charged and 0.1 parts by weight of HBA. Next, add 0.1 part by weight of AIBN as a polymerization initiator to 100 parts by weight of the mixture of BA, AA, and HBA, and introduce nitrogen gas while stirring slowly to replace nitrogen in the flask, and then keep the liquid temperature in the flask at around 55°C Polymerization was carried out for 7 hours. Next, ethyl acetate was added to the obtained reaction liquid, and the solution of the (meth)acrylic-type polymer (A-1) was obtained by adjusting to solid content concentration 12 weight%. The weight average molecular weight (Mw) of (meth)acryl-type polymer (A-1) was 2.2 million. Regarding HSP, δD, δP, and δH of the (meth)acrylic polymer (A-1) were 16.75 MPa ^1/2 , 3.49 MPa ^1/2 , and 5.38 MPa ^1/2 , respectively.

(Synthesis Example 2) In the same manner as in Synthesis Example 1, (meth)acrylic polymer The solution of substance (A-2). The weight average molecular weight (Mw) of a (meth)acrylic-type polymer (A-2) was 2.2 million. Regarding HSP, δD, δP, and δH of the (meth)acrylic polymer (A-2) were 17.05 MPa ^1/2 , 3.49 MPa ^1/2 , and 5.43 MPa ^1/2 , respectively.

(Synthesis Example 3) Except for changing the monomers used to 74.9 parts by weight of BA, 20.0 parts by weight of BzA, 5.0 parts by weight of AA, and 0.1 parts by weight of HBA, a (meth)acrylic polymer was obtained in the same manner as in Synthesis Example 1. The solution of substance (A-3). The weight average molecular weight (Mw) of a (meth)acrylic-type polymer (A-3) was 2.3 million. Regarding HSP, δD, δP, and δH of the (meth)acrylic polymer (A-3) were 17.15 MPa ^1/2 , 3.49 MPa ^1/2 , and 5.44 MPa ^1/2 , respectively.

The weight average molecular weight (Mw) and the distance Ra of HSP are summarized in Table 1 below for the types and feeding amounts of the monomers and polymerization initiators used in Synthesis Examples 1 to 3, and the obtained polymers. In addition, δD, δP, and δH of C/L from the polymer are 20.50MPa ^1/2 , 12.40MPa ^1/2 , and 9.60MPa ^1/2 , respectively.

[Table 1]

[Production of adhesive composition and adhesive sheet] (Manufacturing example 1~8) As shown in Table 2 below, a solvent-type adhesive composition was obtained by mixing a crosslinking agent and the like with respect to 100 parts by weight of solid content of the (meth)acrylic polymer (A).

[Table 2]

Next, the adhesive composition prepared in each production example was coated on the peeling surface of the peeling film with a silicone treatment on the peeling surface, that is, on the peeling surface of a PET film (manufactured by Mitsubishi Polyester Film, MRF38) with a thickness of 38 µm. The coating film is formed, and it is placed in an environment of 23°C until it is preheated (storage time r), and the preheating and main heating are continuously performed in an air circulation constant temperature oven while conveying the substrate film and the coating film. And the adhesive sheets of Examples 1-25 and Comparative Examples 1-5 having a predetermined thickness were formed. The standing time r, and the conditions of preheating and main heating are shown in Table 3 below. In addition, the preheating and main heating temperatures are respectively the set temperatures of the preheating section and the main heating section in the above-mentioned oven. The preheating and formal heating times are the time for the substrate film and the coating film to pass through the preheating zone and the formal heating zone respectively.

[table 3]

The evaluation results of the produced adhesive sheets are shown in Table 4 below. And, the cross-sectional images of the adhesive sheets of Examples 3, 8, 9 and Comparative Example 3 obtained by TEM are shown in FIGS. 7A to 7D . In addition, the states 1 to 5 of the domains in Table 4 are as follows. State 1: Number of evaluation areas with 1st domain State 2: For all the first fields, the shortest distance between adjacent first fields State 3: For all second areas, the shortest distance between adjacent second areas Status 4: The number of evaluation areas where the number of 2nd domains is 10 or less State 5: Ratio of fields in which the shortest distance between adjacent second fields is 100nm or more in all second fields

[Table 4]

As shown in Table 4, compared with the adhesive sheet of the comparative example, the adhesive sheet of the example is suitable for suppressing the change of a dimension, and is excellent in transparency and durability.

Industrial availability The adhesive sheet of the present invention can be used, for example, as an optical adhesive sheet used in an optical laminate and/or an image display device.

1: Adhesive sheet 2: Optical film 2A: Retardation film 2B: polarizer 3: Peel off the lining 4: interlayer adhesive 5: Protective film 6: Image forming layer 7: Substrate 10A, 10B, 10C, 10D: optical laminates 11,20: Image display device

Fig. 1 is a cross-sectional view schematically showing an example of the adhesive sheet of the present invention. Fig. 2 is a cross-sectional view schematically showing an example of an optical laminate including an adhesive sheet of the present invention. Fig. 3 is a cross-sectional view schematically showing an example of an optical laminate including an adhesive sheet of the present invention. Fig. 4 is a cross-sectional view schematically showing an example of an optical laminate including an adhesive sheet of the present invention. Fig. 5 is a cross-sectional view schematically showing an example of an optical laminate including an adhesive sheet of the present invention. Fig. 6 is a cross-sectional view schematically showing an example of an image display device provided with an adhesive sheet of the present invention. 7A is a diagram showing a cross-sectional image of the adhesive sheet produced in Example 3 obtained by a transmission electron microscope (TEM). FIG. 7B is a diagram showing a cross-sectional image of the adhesive sheet prepared in Example 8 obtained by TEM. FIG. 7C is a diagram showing a cross-sectional image of the adhesive sheet produced in Example 9 obtained by TEM. FIG. 7D is a diagram showing a cross-sectional image of the adhesive sheet produced in Comparative Example 3 obtained by TEM.

1: Adhesive sheet

Claims (16)

An adhesive sheet in which 10 evaluation areas of 1.5 µm square are arbitrarily set on the cross-sectional image of the adhesive sheet, and when an island-like area with a short diameter of 100 nm or more is defined as the first area, the evaluation area of the first area exists The number is less than 5; and The adhesive sheet has a haze of 0.1% or more. The adhesive sheet according to claim 1, wherein the shortest distance between adjacent first areas of all the first areas observed in the set evaluation area is 300 nm or more. In the adhesive sheet according to claim 1 or 2, when the island-shaped region having a short diameter of 50 nm or more and less than 100 nm is defined as the second area, the number of the second area in the evaluation area set above is 10 or less The number of the aforementioned evaluation areas is 3 or more. The adhesive sheet according to any one of Claims 1 to 3, when an island-shaped region having a short diameter of 50 nm or more and less than 100 nm is defined as the second area, regarding all of the aforementioned items observed in the aforementioned set evaluation area 2 domains, the shortest distance between adjacent 2nd domains is 150 nm or more. The adhesive sheet according to any one of Claims 1 to 4, when an island-like region having a short axis of 50 nm or more and less than 100 nm is defined as the second area, all of the aforementioned second areas observed in the aforementioned set evaluation area Among the areas, the ratio of the second areas in which the shortest distance between the adjacent second areas is 100 nm or more is 50% or more. The adhesive sheet according to any one of Claims 1 to 5, wherein the storage elastic modulus G'(25°C) is 0.15 MPa or more. The adhesive sheet according to any one of Claims 1 to 6, whose storage elastic modulus G'(25°C) is less than 0.5 MPa. The adhesive sheet according to any one of Claims 1 to 7, which is formed of an adhesive composition comprising a (meth)acrylic polymer (A) as a main component and further comprising an isocyanate polymer. Joint agent (B). The adhesive sheet according to claim 8, wherein the first field includes a polymer of the isocyanate-based crosslinking agent (B). The adhesive sheet according to Claim 8 or 9, wherein in the aforementioned adhesive composition, relative to 100 parts by weight of the aforementioned (meth)acrylic polymer (A), the blending amount of the aforementioned isocyanate-based crosslinking agent (B) is 1.5 parts by weight or more. The adhesive sheet according to any one of claims 8 to 10, wherein the isocyanate-based crosslinking agent (B) is diisocyanate-based toluene. The adhesive sheet according to any one of claims 8 to 11, wherein the (meth)acrylic polymer (A) contains a structural unit derived from an aromatic ring-containing monomer. The adhesive sheet according to any one of claims 8 to 12, wherein the (meth)acrylic polymer (A) contains a constituent unit derived from a hydroxyl group-containing monomer in a content of 1% by weight or less. The adhesive sheet according to any one of claims 8 to 13, wherein the adhesive composition is a solvent type. An optical laminate comprising the adhesive sheet and the optical film according to any one of Claims 1 to 14. An image display device comprising the optical laminate according to claim 15.

Images