JP6743856B2 - Adhesive sheet for bonding optical components - Google Patents

Description

The present invention relates to an adhesive sheet for laminating optical members.

Conventionally, a display device such as a liquid crystal display (LCD) and an input device used in combination with a display device such as a touch panel have been widely used. In the production of these display devices and input devices, transparent adhesive sheets are used for the purpose of bonding optical members.

For example, in Patent Document 1, a double-sided adhesive consisting of a flexible base material layer, a first black layer and a second black layer, and a laminate including a first pressure-sensitive adhesive layer and a second pressure-sensitive adhesive layer. A sheet is disclosed. In such a case, the pressure-sensitive adhesive sheet used for bonding the black layer may be required to have a design property that does not impair the black appearance.

By the way, a method of adding a pigment to an adhesive sheet is also known as a means for imparting a black appearance to the adhesive sheet. For example, Patent Document 2 discloses a black foil adhesive containing an adhesive component, a black pigment, and a styrene-maleic acid resin.

JP, 2005-060435, A JP, 2013-32430, A

As described above, a black pressure-sensitive adhesive sheet obtained by coloring a base material or a pressure-sensitive adhesive is known, but such a pressure-sensitive adhesive sheet is not expected to be bonded to the display surface, and the design of the pressure-sensitive adhesive sheet The sex was not examined. Further, since the conventional black adhesive sheet has a high ultraviolet transmittance, a black adhesive sheet having a low ultraviolet transmittance may be required for sticking to a display surface.

Therefore, the inventors of the present invention, in order to solve such a problem of the conventional technology, when it is attached to a display or the like that displays a black screen, it is a pressure-sensitive adhesive sheet that can enhance its design, the ultraviolet transmittance We proceeded with the study for the purpose of providing an adhesive sheet that is kept low.

As a result of intensive studies to solve the above problems, the present inventors have found that a pressure-sensitive adhesive sheet containing an acrylic polymer has a coloring agent containing at least one selected from metal oxides and carbon black and ultraviolet absorption. By compounding the agent, it is possible to obtain a pressure-sensitive adhesive sheet having a low ultraviolet transmittance, which is a pressure-sensitive adhesive sheet that can enhance its design when the pressure-sensitive adhesive sheet is attached to a display that displays a black screen. I found it.
Specifically, the present invention has the following configurations.

[1] Including an acrylic polymer, a colorant and an ultraviolet absorber,
A pressure-sensitive adhesive sheet for optical member bonding, wherein the colorant contains at least one selected from metal oxides and carbon black.
[2] The pressure-sensitive adhesive sheet for optical member bonding according to [1], wherein the colorant is a metal oxide.
[3] The pressure-sensitive adhesive sheet for laminating optical members according to [1] or [2], wherein the acrylic polymer has an acid value of 50 mgKOH/g or less.
[4] The pressure-sensitive adhesive sheet for optical member bonding according to any one of [1] to [3], which has a total light transmittance of 40 to 80%.
[5] The pressure-sensitive adhesive sheet for laminating optical members according to any one of [1] to [4], which has a haze of 0.5 to 15%.
[6] The pressure-sensitive adhesive sheet for laminating optical members according to any one of [1] to [5], wherein the colorant has a primary average particle diameter of 0.1 to 15 μm.
[7] The pressure-sensitive adhesive sheet for optical member bonding according to any one of [1] to [6], wherein the ultraviolet absorber is represented by the following general formula (1) or (2):
In the general formula (1), R ¹ represents a hydrogen atom, a halogen atom, an alkoxy group having 1 to 4 carbon atoms, a nitro group or a cyano group, and R ² represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. R ³ represents an alkyl group-based structure;
In the general formula (2), R ⁴ , R ⁵ and R ⁶ are hydrogen atoms, hydroxyl groups, alkyl group-based structures or halogen atoms, and all of R ⁴ , R ⁵ and R ⁶ are hydrogen atoms. There is no.
[8] The pressure-sensitive adhesive sheet for laminating optical members according to any one of [1] to [7], which has a thickness of 10 to 5000 μm.

According to the present invention, a pressure-sensitive adhesive sheet for optical member bonding, which can enhance its design when bonded to a display or the like displaying a black screen, wherein the pressure-sensitive adhesive member for optical member bonding has a low ultraviolet transmittance. You can get a sheet.

FIG. 1 is a schematic view showing a cross section of an adhesive sheet having a release sheet.

Hereinafter, the present invention will be described in detail. The description of the constituents described below may be made based on typical embodiments or specific examples, but the present invention is not limited to such embodiments. In addition, in this specification, the numerical range represented using "-" means the range which includes the numerical value described before and after "-" as a lower limit and an upper limit.

(Adhesive sheet)
The present invention relates to a pressure-sensitive adhesive sheet used for laminating optical members. The pressure-sensitive adhesive sheet of the present invention contains an acrylic polymer, a colorant and an ultraviolet absorber, and the colorant contains at least one selected from metal oxides and carbon black.

Since the pressure-sensitive adhesive sheet for laminating optical members of the present invention (hereinafter, also referred to as a pressure-sensitive adhesive sheet) has the above-mentioned configuration, it can enhance its designability when it is laminated to a display or the like that displays a black screen. it can. Specifically, when the pressure-sensitive adhesive sheet of the present invention is attached to a display that displays a black screen, the display has a display and a display because the degree of black coloring of the display (preferability of the degree of blackness) can be increased. The design of the display device can be improved. Further, even if the display does not display a black screen, the degree of blackness of the display is increased by sticking the adhesive sheet, so that a sense of unity with the surroundings is emphasized and the design is enhanced. Furthermore, the pressure-sensitive adhesive sheet of the present invention can keep the ultraviolet transmittance low. Therefore, it is possible to suppress deterioration of the adherend to which the adhesive sheet is attached due to ultraviolet rays.

Further, the pressure-sensitive adhesive sheet for laminating optical members of the present invention has high visibility, and even when it is laminated on the visible surface side of a display, for example, characters displayed in the display are prevented from bleeding. As described above, the pressure-sensitive adhesive sheet for laminating an optical member of the present invention has succeeded in not lowering the visibility of a display or the like while enhancing the degree of black coloration of the display or the like.

The total light transmittance of the pressure-sensitive adhesive sheet is preferably 40% or more. The total light transmittance of the pressure-sensitive adhesive sheet is preferably 80% or less, more preferably 75% or less, further preferably 70% or less. By setting the total light transmittance of the pressure-sensitive adhesive sheet within the above range, the degree of black coloration of a display or the like can be increased.

The haze of the pressure-sensitive adhesive sheet is preferably 0.5% or more. The haze of the pressure-sensitive adhesive sheet is preferably 30% or less, more preferably 25% or less, further preferably 20% or less, and particularly preferably 15% or less. By setting the haze of the pressure-sensitive adhesive sheet within the above range, it is possible to maintain the visibility while enhancing the degree of black coloring of a display or the like.

The thickness of the pressure-sensitive adhesive sheet is preferably 10 μm or more, more preferably 20 μm or more, and further preferably 50 μm or more. Moreover, the thickness of the pressure-sensitive adhesive sheet is preferably 5000 μm or less, more preferably 3000 μm or less, and further preferably 1000 μm or less. By setting the thickness of the pressure-sensitive adhesive sheet to be equal to or less than the above upper limit, it is possible to prevent water vapor from invading from the end portion and improve durability. On the other hand, when the thickness of the pressure-sensitive adhesive sheet is at least the above lower limit, the pressure-sensitive adhesive sheet can be easily handled.

The pressure-sensitive adhesive sheet of the present invention may be a single-layer pressure-sensitive adhesive sheet. The pressure-sensitive adhesive sheet may be a single-sided pressure-sensitive adhesive sheet having a substrate (preferably a transparent substrate) on one side, or a double-sided pressure-sensitive adhesive sheet. The double-sided pressure-sensitive adhesive sheet may be a single-layer pressure-sensitive adhesive sheet composed of a pressure-sensitive adhesive layer, a multi-layer pressure-sensitive adhesive sheet in which a plurality of pressure-sensitive adhesive layers are laminated, or a multi-layer pressure-sensitive adhesive layer in which another pressure-sensitive adhesive layer is laminated between pressure-sensitive adhesive layers. Sheet, a multilayer adhesive sheet in which a support is laminated between adhesive layers, and a multilayer adhesive sheet in which an adhesive layer is laminated on one side of a support and another adhesive layer is laminated on the other side Is mentioned. When the double-sided pressure-sensitive adhesive sheet has a support, it is preferable to use a transparent support as the support. As the support, a general film used in the optical field, like the transparent substrate, can be used. Such a double-sided pressure-sensitive adhesive sheet is excellent in transparency as the pressure-sensitive adhesive sheet as a whole, and thus can be suitably used for bonding optical members to each other.

As shown in FIG. 1, the present invention may be directed to a pressure-sensitive adhesive sheet with a release sheet, which comprises release sheet 12a and release sheet 12b on both surfaces of pressure-sensitive adhesive sheet 11. As the release sheet, a peelable laminated sheet having a release sheet base material and a release agent layer provided on one side of the release sheet base material, or a polyolefin film such as a polyethylene film or a polypropylene film as a low polarity base material. Is mentioned.

Papers and polymer films are used as the base material for the release sheet in the release laminate sheet. For optical use, a polymer film is preferably used in order to prevent foreign matter from entering. As the release agent constituting the release agent layer, for example, a general-purpose addition type or condensation type silicone type release agent or a long chain alkyl group-containing compound is used. In particular, an addition type silicone release agent having high reactivity is preferably used.
Specific examples of the silicone release agent include BY24-4527 and SD-7220 manufactured by Toray Dow Corning Silicone Co., Ltd., KS-3600, KS-774 and X62-2600 manufactured by Shin-Etsu Chemical Co., Ltd. Is mentioned. Further, the silicone release agent may contain a silicone resin which is an organosilicon compound having SiO ₂ units and (CH ₃ ) ₃ SiO _1/2 units or CH ₂ ═CH(CH ₃ )SiO _1/2 units. preferable. Specific examples of the silicone resin include BY24-843, SD-7292, and SHR-1404 manufactured by Toray Dow Corning Silicone Co., Ltd., and KS-3800 and X92-183 manufactured by Shin-Etsu Chemical Co., Ltd.
A commercially available product may be used as the peelable laminated sheet. For example, a heavy separator film which is a release-treated polyethylene terephthalate film manufactured by Teijin DuPont Films Co., Ltd., and a light separator film which is a release-treated polyethylene terephthalate film manufactured by Teijin DuPont Films Co., Ltd. may be mentioned. it can.

When the pressure-sensitive adhesive sheet of the present invention is a double-sided pressure-sensitive adhesive sheet, it is preferable to have a pair of release sheets having different release forces. That is, it is preferable that one release sheet and the other release sheet have different release properties in order to facilitate the release. When the releasability from one side and the releasability from the other side are different, it becomes easy to first release only the release sheet having the higher releasability.

The gel fraction of the pressure-sensitive adhesive sheet of the present invention is preferably 30 to 100%, more preferably 40 to 100%, and further preferably 50 to 100%.

(Acrylic polymer)
The acrylic polymer is not particularly limited as long as it has an acrylic monomer unit. For example, a non-crosslinkable (meth)acrylic acid ester unit (a1) and an acrylic monomer unit having a crosslinkable functional group. It preferably contains (a2). In the present specification and claims, the “unit” is a repeating unit (monomer unit) constituting a polymer.

The non-crosslinkable (meth)acrylic acid ester unit (a1) is a repeating unit derived from a (meth)acrylic acid alkyl ester. Examples of alkyl (meth)acrylates include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, and (meth). Isobutyl acrylate, t-butyl (meth)acrylate, n-pentyl (meth)acrylate, n-hexyl (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-undecyl (meth)acrylate, (meth) Examples thereof include n-dodecyl acrylate, stearyl (meth)acrylate, methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, cyclohexyl (meth)acrylate, and benzyl (meth)acrylate. These may be used alone or in combination of two or more.
Among the above-mentioned (meth)acrylic acid alkyl esters, since the adhesiveness is high, methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. At least one selected from is preferable.

The acrylic monomer unit (a2) having a crosslinkable functional group is selected from a carboxy group-containing monomer unit, a hydroxy group-containing monomer unit, an amino group-containing monomer unit and a glycidyl group-containing monomer unit. It is preferably at least one of That is, the acrylic polymer preferably has at least one crosslinkable functional group selected from a carboxy group, a hydroxy group, an amino group, an amide group, a glycidyl group and an isocyanate group.
Examples of the carboxy group-containing monomer unit include acrylic acid and methacrylic acid.
The hydroxy group-containing monomer unit is a repeating unit derived from the hydroxy group-containing monomer. Examples of the hydroxy group-containing monomer include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, and 2-hydroxypropyl (meth)acrylate; Examples thereof include (meth)acrylic acid [(mono-, di- or poly)alkylene glycol] such as (meth)acrylic acid mono(diethylene glycol), and (meth)acrylic acid lactone such as (meth)acrylic acid monocaprolactone.
Examples of the amino group-containing monomer unit include a repeating unit derived from an amino group-containing monomer such as (meth)acrylamide and allylamine.
Examples of the glycidyl group-containing monomer unit include a repeating unit derived from a glycidyl group-containing monomer such as glycidyl (meth)acrylate.

The content of the acrylic monomer unit (a2) having a crosslinkable functional group in the acrylic polymer is preferably 0.01 to 40% by mass, more preferably 0.5 to 35% by mass. By setting the content of the acrylic monomer unit (a2) having a crosslinkable functional group within the above range, the crosslinkability and tackiness of the acrylic polymer can be easily controlled.

The acrylic polymer may further include units derived from an alkoxyalkyl group-containing (meth)acrylate. The alkoxyalkyl group-containing (meth)acrylate is an alkoxyalkyl (meth)acrylate. As the alkoxyalkyl (meth)acrylate, for example, an alkoxyalkyl (meth)acrylate in which the alkoxy group has 1 to 12 carbon atoms and the alkylene group bonded to the alkoxy group has 1 to 18 carbon atoms is preferable. The alkoxy group preferably has 1 to 8 carbon atoms, more preferably 1 to 4 carbon atoms, and particularly preferably 1 or 2 carbon atoms. Further, the alkylene group bonded to the alkoxy group preferably has 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms, further preferably 1 to 4 carbon atoms, and particularly preferably 1 to 3 carbon atoms. preferable.

Examples of such alkoxyalkyl (meth)acrylates include 2-methoxymethyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-ethoxymethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 3-methoxypropyl (meth)acrylate, 3-ethoxypropyl (meth)acrylate, 4-methoxybutyl (meth)acrylate, 4-ethoxybutyl (meth)acrylate and the like can be mentioned.

The acrylic polymer may further include units derived from a nitrogen-containing monomer. The nitrogen-containing monomer is a monomer containing a nitrogen element in one molecule. Examples of the nitrogen-containing monomer include dimethylacrylamide, diethylacrylamide, acryloylmorpholine, hydroxyethylacrylamide, methylolacrylamide, methoxymethylacrylamide, ethoxymethylacrylamide, dimethylaminoethylacrylamide, N-vinylcaprolactam and N-vinyl-2-. Pyrrolidone, dimethylaminoethyl (meth)acrylate, N-vinylformamide and the like can be mentioned. Among them, the nitrogen-containing monomer is preferably at least one selected from acrylamide derivatives, amino group-containing monomers and nitrogen-containing heterocycle-containing monomers, and more preferably acrylamide derivatives. The acrylamide derivative is more preferably at least one selected from dimethylacrylamide, diethylacrylamide and acryloylmorpholine, and particularly preferably dimethylacrylamide.

The acrylic polymer may have other monomer units, if necessary. The other monomer may be one that can be copolymerized with the above-mentioned acrylic monomer, and examples thereof include (meth)acrylonitrile, vinyl acetate, styrene, vinyl chloride, vinylpyrrolidone, and vinylpyridine. The content of the other monomer unit in the acrylic polymer is preferably 20% by mass or less, and more preferably 15% by mass or less.

The acid value of the acrylic polymer is preferably 50 mgKOH/g or less, more preferably 40 mgKOH/g or less, further preferably 30 mgKOH/g or less, and further preferably 20 mgKOH/g or less. It is even more preferably 10 mgKOH/g or less, and particularly preferably 5 mgKOH/g or less. The acid value of the acrylic polymer may be 0 mgKOH/g. When the acid value of the acrylic polymer is within the above range, the pressure-sensitive adhesive sheet of the present invention is excellent in color loss resistance. Specifically, by setting the acid value of the acrylic polymer within the above range, it is possible to suppress an increase in total light transmittance even when the pressure-sensitive adhesive sheet is left under high temperature and high humidity conditions for a long time. it can. It is preferable that the total light transmittance is measured before and after the pressure-sensitive adhesive sheet is placed in an environment of 85° C. and relative humidity of 85% for 240 hours, and the change amount of the total light transmittance calculated from the value is less than 10%. Furthermore, the total light transmittance of the pressure-sensitive adhesive sheet after being placed in an environment of 85° C. and relative humidity of 85% for 240 hours is preferably less than 85%. The change amount of the total light transmittance is calculated by the following formula.
Change (%) = (total light transmittance of sample before treatment)-(total light transmittance of sample after treatment)

The acid value of the acrylic polymer is measured according to JIS K 0070 (1992). Specifically, first, about 2 g of a sample is precisely weighed in a 100 ml Erlenmeyer flask using a precision balance, and 10 ml of a mixed solvent of ethanol/diethyl ether=1/1 (weight ratio) is added and dissolved. Further, 1 to 3 drops of a phenolphthalein ethanol solution as an indicator is added to this container and stirred sufficiently until the sample becomes uniform. This is titrated with a 0.1 N potassium hydroxide-ethanol solution, and when the light pink color of the indicator continues for 30 seconds, the neutralization end point is determined. The value obtained by using the following calculation formula (1) from the result is used as the acid value of the sample.
Acid value (mgKOH/g)=[B×f×5.611]/S (1)
In the calculation formula (1), B is the amount (ml) of the 0.1N potassium hydroxide-ethanol solution used, f is the 0.1N potassium hydroxide-ethanol solution factor, and S is the sample It is the collected amount (g).

The weight average molecular weight of the acrylic polymer is preferably 100,000 to 2,000,000, more preferably 200,000 to 1,500,000. The weight average molecular weight of the acrylic polymer is a value before being crosslinked with a crosslinking agent described later. The weight average molecular weight is a value measured by size exclusion chromatography (SEC) and determined based on polystyrene. As the acrylic polymer, a commercially available one may be used, or one synthesized by a known method may be used.

(Colorant)
The pressure-sensitive adhesive sheet of the present invention contains at least one colorant selected from metal oxides and carbon black. The colorant is preferably a black pigment, particularly preferably a metal oxide. By using the metal oxide as the colorant, the visibility of the pressure-sensitive adhesive sheet can be more effectively enhanced. In addition to the metal oxide and the carbon black, the colorant may include other colorants. Examples of other colorants include aniline black and activated carbon.

As the metal oxide, copper oxide, triiron tetraoxide, manganese dioxide, titanium oxide, zinc oxide, zirconium oxide, barium titanate, potassium titanate, iron titanate, copper-chromium oxide, copper-manganese oxide, Examples thereof include copper-iron-manganese oxide, copper-chromium-manganese oxide or copper-iron-chromium oxide, and titanium black. Among them, the metal oxide is more preferably a metal oxide whose metal species is selected from copper, iron and manganese. By selecting the above type as the colorant, the coloring stability becomes good.

The colorant is fine particles, and the primary average particle diameter of the colorant is preferably 0.1 μm or more. The primary average particle diameter of the colorant is preferably 15 μm or less, more preferably 12 μm or less, further preferably 10 μm or less, and particularly preferably 5 μm or less. By setting the primary average particle diameter of the colorant within the above range, the visibility of the pressure-sensitive adhesive sheet can be more effectively enhanced.

The content of the colorant is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, and 0.2 parts by mass or more with respect to 100 parts by mass of the acrylic polymer. Is more preferable. Further, the content of the colorant is preferably 10 parts by mass or less, and more preferably 5 parts by mass or less with respect to 100 parts by mass of the acrylic polymer.

The colorant is preferably mixed with the acrylic polymer while being dispersed in the dispersion resin. Examples of the dispersion resin include polyester resin, urethane resin, acrylic resin, and polyether resin.

(UV absorber)
The pressure-sensitive adhesive sheet of the present invention contains an ultraviolet absorber. The ultraviolet absorber can be selected from those having a maximum absorption wavelength in the ultraviolet region. In the present invention, it is particularly preferable to use an ultraviolet absorber having a maximum absorption wavelength at a wavelength of 350 nm or more. Examples of the ultraviolet absorber having a maximum absorption wavelength at a wavelength of 350 nm or more include compounds represented by the following general formula (1) or (2).

In the above formula, R ¹ represents a hydrogen atom, a halogen atom, an alkoxy group having 1 to 4 carbon atoms, a nitro group or a cyano group, R ² represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms, R ^{2 3} represents an alkyl group-based structure.

In the above formula, R ⁴ , R ⁵ and R ⁶ are a hydrogen atom, a hydroxyl group, an alkyl group structure or a halogen atom, and all of R ⁴ , R ⁵ and R ⁶ are not hydrogen atoms. The alkyl group-based structure is a concept including a substituted or unsubstituted alkyl group and a substituted group mainly composed of an alkyl group such as a substituted or unsubstituted alkoxy group.

Above all, an ultraviolet absorber which improves compatibility by introducing an alkyl group having a large molecular weight into the aromatic ring of the basic skeleton and shows a liquid or oil at 23° C. can be particularly preferably used. Here, the expression of liquid or oil at 23° C. means a state in which only the ultraviolet absorber has fluidity without a diluting solvent.

A commercial item can be used as an ultraviolet absorber. Examples of commercially available products include triazine-based UV absorbers (Tinuvin 477) and benzotriazole-based UV absorbers (Tinuvin 109, Tinuvin 384-2, Tinuvin PS) manufactured by BASF Japan Ltd., and the like.

The content of the ultraviolet absorber is preferably 0.1 to 10 parts by mass, more preferably 0.5 to 8 parts by mass, and 1 to 6 parts by mass with respect to 100 parts by mass of the acrylic polymer. It is more preferable that there is. The content of the ultraviolet absorber in the present invention is preferably adjusted to an amount such that the ultraviolet transmittance at a wavelength of 380 nm is less than 10%. That is, the ultraviolet transmittance of the pressure-sensitive adhesive sheet of the present invention at a wavelength of 380 nm is preferably less than 10%. The above ultraviolet absorbers may be used alone or in combination of two or more kinds, and when two or more kinds are used in combination, the total mass is preferably within the above range.

(Crosslinking agent)
The pressure-sensitive adhesive composition forming the pressure-sensitive adhesive sheet of the present invention may contain a crosslinking agent. The cross-linking agent can be appropriately selected in consideration of the reactivity with the cross-linkable functional group of the acrylic polymer. For example, it can be selected from known crosslinking agents such as an isocyanate compound, an epoxy compound, an oxazoline compound, an aziridine compound, a metal chelate compound and a butylated melamine compound. Among these, it is preferable to use an isocyanate compound or an epoxy compound because the hydroxy group-containing (meth)acrylate can be easily crosslinked. That is, the crosslinking agent is preferably at least one selected from a bifunctional or higher functional epoxy compound and a bifunctional or higher functional isocyanate compound, and more preferably a bifunctional or higher functional isocyanate compound.

Examples of the isocyanate compound include tolylene diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate. Examples of commercially available products include tolylene diisocyanate compound (Coronate L, manufactured by Nippon Polyurethane Industry Co., Ltd.), xylylene diisocyanate compound (Takenate D-110N, manufactured by Mitsui Chemicals, Inc.) and the like.
Examples of the epoxy compound include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, polypropylene glycol diglycidyl ether, glycerin diglycidyl ether, neopentyl glycol diglycidyl ether, 1,6-hexanediol di Glycidyl ether, tetraglycidyl xylene diamine, 1,3-bis(N,N-diglycidylaminomethyl)cyclohexane, trimethylolpropane polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, sorbitol polyglycidyl ether, etc. Can be mentioned.
Examples of commercially available products include 1,3-bis(N,N-diglycidylaminomethyl)benzene (Mitsubishi Gas Chemical Co., Inc., TETRAD-X), 1,3-bis(N,N-diglycidylaminomethyl). ) Cyclohexane (Mitsubishi Gas Chemical Co., Inc., TETRAD-C) and the like.

The content of the cross-linking agent in the pressure-sensitive adhesive composition is appropriately selected according to the desired adhesiveness and the like, but is preferably 0.01 to 5 parts by mass, and 0.1 to 100 parts by mass of the acrylic polymer. Is more preferably 3 parts by mass. By setting the content of the cross-linking agent within the above range, the processability can be further enhanced. As the cross-linking agent, one kind may be used alone, or two or more kinds may be used in combination. When two kinds or more are used in combination, the total mass is preferably within the above range.

(solvent)
The pressure-sensitive adhesive composition forming the pressure-sensitive adhesive sheet of the present invention may contain a solvent. In this case, the solvent is used for improving the coating suitability of the pressure-sensitive adhesive composition. Examples of the solvent include hydrocarbons such as hexane, heptane, octane, toluene, xylene, ethylbenzene, cyclohexane, and methylcyclohexane; halogenated hydrocarbons such as dichloromethane, trichloroethane, trichloroethylene, tetrachloroethylene, and dichloropropane; methanol, ethanol, Alcohols such as propanol, isopropyl alcohol, butanol, isobutyl alcohol, diacetone alcohol; ethers such as diethyl ether, diisopropyl ether, dioxane, tetrahydrofuran; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, isophorone, cyclohexanone; methyl acetate , Ethyl acetate, butyl acetate, isobutyl acetate, amyl acetate, ethyl butyrate and other esters; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene Examples thereof include polyols such as glycol monomethyl ether acetate and derivatives thereof.

The content of the solvent in the pressure-sensitive adhesive composition is not particularly limited, but is preferably 25 to 500 parts by mass, and more preferably 30 to 400 parts by mass with respect to 100 parts by mass of the acrylic polymer.
Further, the content of the solvent is preferably 10 to 90% by mass, and more preferably 20 to 80% by mass, based on the total mass of the pressure-sensitive adhesive composition. As the solvent, one type may be used alone, or two or more types may be used in combination. When two or more types are used in combination, the total mass is preferably within the above range.

(Other ingredients)
The pressure-sensitive adhesive sheet may contain components other than the above components as long as the effects of the present invention are not impaired. Examples of other components include components known as additives for pressure-sensitive adhesives. For example, a plasticizer, an antioxidant, a metal corrosion inhibitor, a tackifier, a silane coupling agent, and a light stabilizer such as a hindered amine compound can be selected as necessary. Further, a dye or a pigment may be added for the purpose of coloring.
Examples of the plasticizer include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl caproate, vinyl caprylate, vinyl caprate, vinyl laurate, vinyl myristate, vinyl palmitate, vinyl stearate, vinyl cyclohexanecarboxylate, and benzoic acid. Examples thereof include carboxylic acid vinyl esters such as vinyl acid salt and styrene.
Examples of the antioxidant include a phenol-based antioxidant, an amine-based antioxidant, a lactone-based antioxidant, a phosphorus-based antioxidant, a sulfur-based antioxidant and the like. These antioxidants may be used alone or in combination of two or more.
As the metal corrosion inhibitor, a benzotriazole resin can be mentioned as a preferable example because of the compatibility of the pressure-sensitive adhesive and the high effect.
Examples of the tackifier include rosin resin, terpene resin, terpene phenol resin, coumarone indene resin, styrene resin, xylene resin, phenol resin, petroleum resin and the like.
Examples of the silane coupling agent include a mercaptoalkoxysilane compound (eg, a mercapto group-substituted alkoxy oligomer).

<Production method of adhesive sheet>
The method for producing a pressure-sensitive adhesive sheet of the present invention preferably includes a step of applying a pressure-sensitive adhesive composition on a release sheet to form a coating film.

The coating of the pressure-sensitive adhesive composition can be carried out using a known coating device. Examples of the coating device include a blade coater, an air knife coater, a roll coater, a bar coater, a gravure coater, a microgravure coater, a rod blade coater, a lip coater, a die coater, and a curtain coater.

The pressure-sensitive adhesive sheet manufacturing method preferably includes a step of heating the coating film. In this case, a known heating device such as a heating furnace or an infrared lamp can be used to heat the coating film formed by applying the pressure-sensitive adhesive composition.
The agent for producing the pressure-sensitive adhesive sheet may be subjected to an aging treatment of leaving the pressure-sensitive adhesive sheet at a constant temperature for a predetermined period after removing the solvent after coating. The aging treatment can be performed, for example, by leaving it at 23° C. for 7 days.

<Use of adhesive sheet>
The pressure-sensitive adhesive sheet of the present invention is used for application of optical members. Examples of the optical member include various constituent members in optical products such as a touch panel and an image display device, and a scattering prevention film attached to the cover lens of the outermost layer. Above all, it is preferably used for application to the pressure-sensitive adhesive sheet touch panel of the present invention. As a component of the touch panel, for example, an ITO film provided with an ITO film on a transparent resin film, an ITO glass provided with an ITO film on the surface of a glass plate, a transparent conductive film obtained by coating a transparent resin film with a conductive polymer, Examples include hard coat films and anti-fingerprint films. Examples of constituent members of the image display device include an antireflection film, an alignment film, a polarizing film, a retardation film, and a brightness enhancement film used in a liquid crystal display device.
Examples of materials used for these members include glass, polycarbonate, polyethylene terephthalate, polymethyl methacrylate, polyethylene naphthalate, cycloolefin polymer, triacetyl cellulose, polyimide, and cellulose acylate.

The present invention may relate to a laminated body in which the above-mentioned pressure-sensitive adhesive sheet and the above-mentioned optical member are laminated. When manufacturing a laminated body, the process of sticking an adhesive sheet on an optical member is included. In the step of bonding, it is preferable to bond the pressure-sensitive adhesive sheet to the optical member using a hand roller or the like. Further, in order to enhance the adhesion between the pressure-sensitive adhesive sheet and the optical member, autoclave treatment may be performed under the conditions of 20 to 100° C. and 1 to 10 atmospheres.

The features of the present invention will be described more specifically below with reference to Examples and Comparative Examples. The materials, usage amounts, ratios, processing contents, processing procedures, and the like shown in the following examples can be appropriately changed without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be limitedly interpreted by the following specific examples.

<Synthesis of acrylic polymer A>
Acrylic polymer A was made by solution polymerization in ethyl acetate. Butyl acrylate (BA) and 2-hydroxyethyl acrylate (2HEA) were mixed in a mass ratio of 70:30, and AIBN (azobisisobutyronitrile) was dissolved in the solution as a radical polymerization initiator. The solution was heated to 60° C. and random copolymerization was performed to obtain an acrylic polymer A. The solution viscosity of this 35 mass% solution of acrylic polymer A at 23° C. was 6,400 mPa·s. The acid value of acrylic polymer A was 0.0 mgKOH/g.

<Synthesis of acrylic polymer B>
Acrylic polymer B was made by solution polymerization in ethyl acetate. Butyl acrylate (BA), 2-ethylhexyl methacrylate (2EHMA), ethyl acrylate (EA), 2-hydroxyethyl methacrylate (2HEMA) and acrylic acid (AA) are adjusted to a mass ratio of 85:5:4:4:2. And AIBN (azobisisobutyronitrile) as a radical polymerization initiator were dissolved in the solution. The solution was heated to 60° C. and subjected to random copolymerization to obtain an acrylic polymer B. The solution viscosity of this 35 mass% solution of acrylic polymer B at 23° C. was 3,650 mPa·s. The acid value of acrylic polymer B was 1.6 mgKOH/g.

<Synthesis of acrylic polymer C>
Acrylic polymer C was made by solution polymerization in ethyl acetate. Butyl acrylate (BA), methyl acrylate (MA), methyl methacrylate (MMA), and acrylic acid were mixed in a mass ratio of 87:1:4:8, and AIBN (azobisisobutyro) was used as a radical polymerization initiator. Nitrile) was dissolved in the solution. Acrylic polymer C was obtained by heating the solution to 60° C. for random copolymerization. The solution viscosity of this 35 mass% solution of acrylic polymer C at 23° C. was 4,200 mPa·s. The acid value of acrylic polymer C was 60.0 mgKOH/g.

(Example 1)
With respect to 100 parts by mass of the acrylic polymer A, 0.5 parts by mass of an isocyanate-based crosslinking agent (Coronate L-55E manufactured by Tosoh Corporation) as a crosslinking agent, and a triazine-based ultraviolet absorber ((BASF Japan 2 parts by mass of TINUVIN 477 manufactured by Co., Ltd., and 0.06 parts by mass of copper, iron, manganese oxide-based pigment (TM Black 3550 manufactured by Dainichiseika Kogyo Co., Ltd.) as a colorant. Then, ethyl acetate was added as a solvent so that the solid content concentration was 35% by mass to obtain a pressure-sensitive adhesive composition.

The pressure-sensitive adhesive composition was applied onto a first release sheet (heavy separator film, Teijin DuPont Films Co., Ltd., release-treated polyethylene terephthalate film). The coating was performed using a doctor blade YD type manufactured by Yoshimitsu Seiki Co., Ltd. so that the thickness after drying was 25 μm. Then, it was dried at 100° C. for 3 minutes with a hot air dryer to remove the solvent and form an adhesive sheet.
A second release sheet (light separator film, manufactured by Teijin DuPont Films Co., Ltd.), which has been subjected to a release treatment having a higher release property than the first release sheet, is attached to one surface of this pressure-sensitive adhesive sheet, and the pressure-sensitive adhesive with the release sheet is attached. A pressure-sensitive adhesive sheet of Example 1 which is a sheet was obtained.

(Example 2)
A pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet with a release sheet were obtained in the same manner as in Example 1 except that the addition amount of the colorant was changed to 0.22 parts by mass.

(Example 3)
A pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet with a release sheet were obtained in the same manner as in Example 1 except that the coloring agent was changed to 0.1 part by mass of carbon black (manufactured by Toyo Color Co., Ltd., Multilac A903 Black). It was

(Example 4)
With respect to 100 parts by mass of the acrylic polymer B, 0.5 parts by mass of an isocyanate-based crosslinking agent (Coronate L-55E manufactured by Tosoh Corporation) as a crosslinking agent, and a triazine-based ultraviolet absorber ((BASF Japan 2 parts by mass of TINUVIN 477 manufactured by Co., Ltd., 0.2 parts by mass of copper, iron, manganese oxide-based pigment (TM Black 3550 manufactured by Dainichiseika Kogyo Co., Ltd.) as a coloring agent. Then, ethyl acetate was added as a solvent so that the solid content concentration was 35% by mass to obtain a pressure-sensitive adhesive composition.

(Example 5)
With respect to 100 parts by mass of the acrylic polymer C, 0.5 parts by mass of an isocyanate-based crosslinking agent (Coronate L-55E manufactured by Tosoh Corporation) as a crosslinking agent, and a triazine-based ultraviolet absorber ((BASF Japan 2 parts by mass of TINUVIN 477 manufactured by Co., Ltd., and 0.16 parts by mass of copper, iron, manganese oxide-based pigment (TM Black 3550 manufactured by Dainichiseika Kogyo Co., Ltd.) as a colorant. Then, ethyl acetate was added as a solvent so that the solid content concentration was 35% by mass to obtain a pressure-sensitive adhesive composition.

(Comparative Example 1)
A pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet with a release sheet were obtained in the same manner as in Example 1 except that the colorant was not added.

(Comparative example 2)
A pressure-sensitive adhesive composition and a pressure-sensitive adhesive sheet with a release sheet were obtained in the same manner as in Example 1 except that the ultraviolet absorber was not added and the addition amount of the colorant was changed to 0.14 parts by mass.

(Evaluation)
<Optical properties>
The light release separator, which is the second release sheet, was peeled off, and a PET film (Cosmoshine A4300#100, manufactured by Toyobo Co., Ltd.) was bonded using a hand roller instead of the peeled off separator to prepare a laminated film. This laminated film was cut into a size having a width of 50 mm and a length of 50 mm, and the first release sheet was peeled off. Then, the exposed adhesive surface was attached to a slide glass (S9112 manufactured by Matsunami Glass Co., Ltd.) using a hand roller. In this state, it was kept in an autoclave under the conditions of 40° C. and 5 atm for 30 minutes to make it adhere to the glass plate.
About the obtained laminated body, the total light transmittance and haze were measured using the integrating sphere type light transmittance measuring device (Nippon Denshoku Industries Co., Ltd. make, NDH-5000) based on JISK7150. This measurement was performed 3 times, and the average value was used as the measured value.

<Gel fraction>
The pressure-sensitive adhesive sheet was cut into a size of 100 mm×60 mm to prepare a measurement sample. About 0.1 g of the pressure-sensitive adhesive sheet of the measurement sample was collected in a sample bottle, 30 ml of ethyl acetate was added, and the mixture was shaken for 24 hours. Then, the contents of this sample bottle were filtered with a 150-mesh stainless steel wire net, and the residue on the wire net was dried at 100° C. for 1 hour to measure the dry mass (g). The gel fraction was calculated from the obtained dry mass by the following formula 1.
Gel fraction (mass %)=(dry mass/collection mass of adhesive sheet)×100...Equation 1

<Design property>
A sample was prepared in the same manner as the optical property measurement, and was placed on a display displaying a black screen for evaluation.
○: It looked darker than when nothing was placed ×: No change

<Visibility>
A sample was prepared in the same manner as in the optical characteristic measurement, and the sample was placed on a display displaying characters and evaluated.
○: No bleeding or blurring is seen △: Bleeding or blurring is seen ×: Bleeding or blurring is seen and the characters are not legible

<Color loss>
A sample was prepared in the same manner as the measurement of the optical characteristics, placed in an environment of 85° C. and a relative humidity of 85%, and the total light transmittance after 240 hours was measured. In addition, the amount of change was calculated by the following formula based on the total light transmittance of the sample before being placed in an environment of 85° C. and relative humidity of 85%, and evaluated according to the following evaluation criteria.
Change (%) = (total light transmittance of sample before treatment)-(total light transmittance of sample after treatment)
◯: Change in total light transmittance is less than ±10%, and total light transmittance after treatment is less than 85% △: Change in total light transmittance is 10% or more, and total light transmittance after treatment is Less than 85% x: Change in total light transmittance of 10% or more, and total light transmittance after treatment of 85% or more

<UV cut>
A pressure-sensitive adhesive sheet having a transparent film as a base material was cut into 50 mm×50 mm, the light release separator was peeled off, and the sheet was attached to a slide glass (S9112 manufactured by Matsunami Glass Co., Ltd.). In this state, the autoclave was kept under the conditions of 40° C. and 5 atm for 30 minutes to be adhered to the glass plate, and then the heavy release separator was peeled off, and a self-recorded spectrophotometer (model: UV-3100PC, manufactured by Shimadzu Corporation). Was used to measure the spectral transmittance at a wavelength of 380 nm and evaluated according to the following evaluation criteria.
◯: Spectral transmittance of 380 nm wavelength is less than 10% ×: Spectral transmittance of 380 nm wavelength is 10% or more

MO: Metal oxide CB: Carbon black

1 Adhesive Sheet with Release Sheet 11 Adhesive Sheet 12a Release Sheet 12b Release Sheet

Claims (5)

Including acrylic polymer, colorant and UV absorber,
The colorant is a pressure-sensitive adhesive sheet for optical member bonding, which is a black metal oxide,
The acid value of the acrylic polymer is 50 mgKOH/g or less,
The pressure-sensitive adhesive sheet for bonding optical members, wherein the total light transmittance of the pressure-sensitive adhesive sheet for bonding optical members is 40 to 80%. The pressure-sensitive adhesive sheet according to claim 1, which has a haze of 0.5 to 15%. The pressure-sensitive adhesive sheet for laminating optical members according to claim 1 or 2 , wherein the colorant has a primary average particle diameter of 0.1 to 15 µm. The ultraviolet absorber is represented by the following general formula (1) or the pressure-sensitive adhesive sheet for optical member lamination according to any one of claims 1 to 3, those represented by (2);
In the general formula (1), R ¹ represents a hydrogen atom, a halogen atom, an alkoxy group having 1 to 4 carbon atoms, a nitro group or a cyano group, and R ² represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. And R ³ represents an alkyl group-based structure;
In the general formula (2), R ⁴ , R ⁵ and R ⁶ are a hydrogen atom, a hydroxyl group, an alkyl group structure or a halogen atom, and all of R ⁴ , R ⁵ and R ⁶ are hydrogen atoms. There is no. Optical members laminated pressure-sensitive adhesive sheet according to any one of claims 1-4 thickness of 10～5000Myuemu.