JP6565487B2 - Adhesive composition, adhesive and adhesive sheet - Google Patents

Description

  The present invention relates to a pressure-sensitive adhesive composition, a pressure-sensitive adhesive, and a pressure-sensitive adhesive sheet, and more specifically, a pressure-sensitive adhesive composition that forms a pressure-sensitive adhesive having a good balance between water vapor barrier properties and transparency of the pressure-sensitive adhesive layer, and using the same. It is related with the adhesive which becomes, and an adhesive sheet.

  In recent years, display devices such as a liquid crystal display (LCD) and input devices used in combination with the display device such as a touch panel have been widely used in various fields. An organic EL used in an organic device is provided with an organic layer in which an organic charge transport layer or an organic light emitting layer is laminated between an anode and a cathode, and can emit light with high brightness by low voltage direct current drive. It has been attracting attention as a light-emitting element, and an organic device is expected as a display that achieves a reduction in thickness, weight, flexibility, and the like by using a plastic film as a substrate.

  In the manufacture of these display devices and input devices, a transparent adhesive sheet is used for bonding optical members. For example, for bonding a touch panel to various display devices and optical members (protective plates, etc.) A transparent adhesive sheet is used. In addition, if oxygen, water vapor, or the like enters the organic EL element, the electrode is oxidized or the organic substance is denatured. In order to prevent these, an adhesive sheet for sealing the organic EL element is used. It has been.

  In addition to transparency and adhesive properties as an adhesive sheet, there is an increasing demand for gas barrier properties, particularly water vapor barrier properties, for adhesive sheets used for the above purposes.

As such an adhesive that improves the gas barrier property, for example, the water vapor permeability at 40 ° C. and 90% RH measured by a homopolymer cup method having a weight average molecular weight of 500,000 is 500 g / m ² · day or less (meta). Acrylic polymer having a weight average molecular weight of not less than 50,000 and less than 400,000 obtained by copolymerizing 50% by weight of an acrylic acid alkyl ester, a monomer having a hydroxyl group, and a monomer containing a nitrogen-containing monomer. And an adhesive composition containing a crosslinking agent have been proposed (see, for example, Patent Document 1).

JP 2013-47296 A

  However, although the technique disclosed in Patent Document 1 uses a monomer with low moisture permeability, as an acrylic resin, as other monomers, carbon of alkyl group such as methyl acrylate, ethyl acrylate, butyl acrylate, etc. Since a large number of monomers and polar monomers are copolymerized, the moisture permeability of the resin becomes high, and it does not satisfy the barrier properties required with the advancement of technology, and it is still improved. There was room for room.

  In addition, even when an acrylic resin with low moisture permeability is used as a constituent of the acrylic pressure-sensitive adhesive, when the pressure-sensitive adhesive composition is cured with an isocyanate-based crosslinking agent generally used in conventional acrylic pressure-sensitive adhesives However, since the compatibility between the resin and the crosslinking agent is poor, there is a problem that the transparency of the pressure-sensitive adhesive layer is remarkably lowered and the optical properties are deteriorated.

  Therefore, in the present invention, under such a background, the pressure-sensitive adhesive composition that forms a pressure-sensitive adhesive having a good balance between gas barrier properties, in particular, water vapor barrier properties, and transparency of the pressure-sensitive adhesive layer. It aims at providing an adhesive and an adhesive sheet.

  However, as a result of intensive studies in view of such circumstances, the present inventor has found that the acrylic resin obtained by polymerizing a (meth) acrylic acid alkyl ester monomer having a long chain alkyl group is hydrophobic. By using a cross-linking agent having a high specific structure, it was found that an adhesive having an excellent balance between water vapor barrier properties and transparency of the adhesive layer can be obtained, and the present invention has been completed.

  That is, the gist of the present invention is an acrylic resin (A) obtained by polymerizing a polymerization component containing 60% by weight or more of a (meth) acrylic acid alkyl ester monomer (a1) having 12 or more carbon atoms in an alkyl group, And a cross-linking agent (B), and the cross-linking agent (B) is a cross-linking agent containing an alicyclic structure and an isocyanurate skeleton. is there.

  Moreover, in this invention, the adhesive which the said adhesive composition is hardened | cured and the adhesive sheet using the same are also provided.

  In addition, since the crosslinking agent containing the alicyclic structure and the isocyanurate skeleton is generally in the form of pellets, it is necessary to use it by dissolving in advance at the time of use, which makes the operation complicated and crosslinking of the acrylic pressure-sensitive adhesive. Although it was not normally used as an agent, in the present invention, by using a cross-linking agent having such a specific structure, it was surprisingly excellent in adhesion and excellent in balance between gas barrier properties and transparency. It has been found that it has an effect.

  The pressure-sensitive adhesive composition of the present invention is capable of forming a pressure-sensitive adhesive having a good balance between gas barrier properties and the transparency of the pressure-sensitive adhesive layer. It is suitably used for touch panel applications.

The present invention is described in detail below.
In the present invention, (meth) acryl means acryl or methacryl, (meth) acryloyl means acryloyl or methacryloyl, and (meth) acrylate means acrylate or methacrylate. The acrylic resin is a resin obtained by polymerizing a polymerization component containing at least one (meth) acrylate monomer.

First, the acrylic resin (A) contained as an essential component in the pressure-sensitive adhesive composition of the present invention will be described.
The acrylic resin (A) is obtained by polymerizing a polymerization component containing a (meth) acrylic acid alkyl ester (a1) having an alkyl group having 12 or more carbon atoms, preferably further a functional group-containing ethylenic resin. It contains an unsaturated monomer (a2) as a polymerization component, and may further contain another copolymerizable ethylenically unsaturated monomer (a3) as a polymerization component, if necessary.

The (meth) acrylic acid alkyl ester monomer (a1) used in the present invention is required to have a long chain length such that the alkyl group has 12 or more carbon atoms, preferably 15 to 35, particularly preferably. Is 16 to 25, more preferably 17 to 20.
If the number of carbon atoms of the alkyl group is too small, the moisture permeability increases and the effect of the present invention is not exhibited. The upper limit of the carbon number is not particularly limited, but if it is too large, the reactivity during polymerization tends to be lowered.

Specific examples of the (meth) acrylic acid alkyl ester monomer (a1) include, for example, lauryl (meth) acrylate, tridecyl (meth) acrylate, isotridecyl (meth) acrylate, isomyristyl (meth) acrylate, pentadecyl (meth) Acrylate, isopentadecyl (meth) acrylate, hexadecyl (meth) acrylate, isohexadecyl (meth) acrylate, heptadecyl (meth) acrylate, isoheptadecyl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, isotetracosyl Aliphatic (meth) acryl such as (meth) acrylate, 2-dodecyl-hexadecanyl (meth) acrylate, 2-tetradecyl-octadecanyl (meth) acrylate It includes alkyl ester monomers.
These (meth) acrylic acid alkyl ester monomers (a1) may be used alone or in combination of two or more.

  Among these, hexadecyl (meth) acrylate, isohexadecyl (meth) acrylate, heptadecyl (meth) acrylate, isoheptadecyl (meth) acrylate, stearyl (meth) acrylate, and isostearyl (meth) acrylate are preferable in terms of water vapor barrier properties. In particular, stearyl (meth) acrylate and isostearyl (meth) acrylate are preferred from the viewpoints of polymerizability and water vapor barrier properties.

In the present invention, the content of the (meth) acrylic acid alkyl ester monomer (a1) having 12 or more carbon atoms in the alkyl group needs to be 60% by weight or more based on the entire polymerization component. It is preferably ˜99.5% by weight, particularly preferably 70 to 99.5% by weight, more preferably 80 to 99.5% by weight, and particularly preferably 85 to 99% by weight.
If the content is too small, the moisture permeability increases. If the content is too large, the glass transition temperature of the acrylic resin increases, and the adhesion tends to decrease.

  Examples of the functional group-containing ethylenically unsaturated monomer (a2) used in the present invention include a hydroxyl group-containing monomer, a carboxyl group-containing monomer, an amino group-containing monomer, an acetoacetyl group-containing monomer, an isocyanate group-containing monomer, and a glycidyl group-containing monomer. Among these, a hydroxyl group-containing monomer is preferably used in that a crosslinking reaction can be efficiently performed, and an amino group-containing monomer is preferably used in combination in terms of imparting a crosslinking promotion effect.

  Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 5-hydroxypentyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meta ) Acrylic acid hydroxyalkyl esters such as acrylate, caprolactone-modified 2-hydroxyethyl (meth) acrylate and other caprolactone-modified monomers, diethylene glycol (meth) acrylate, polyethylene glycol (meth) acrylate and other oxyalkylene-modified monomers, and other 2-acrylic Primary hydroxyl group-containing monomers such as leuoxyethyl 2-hydroxyethylphthalic acid, N-methylol (meth) acrylamide, N-hydroxyethyl acrylamide; 2 Secondary hydroxyl group-containing monomers such as hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-chloro 2-hydroxypropyl (meth) acrylate; 2,2-dimethyl 2-hydroxyethyl (meth) acrylate and the like There may be mentioned tertiary hydroxyl group-containing monomers. Of these, 2-hydroxyethyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and the like are preferable.

  Examples of the carboxyl group-containing monomer include (meth) acrylic acid, acrylic acid dimer, crotonic acid, maleic acid, maleic anhydride, fumaric acid, citraconic acid, glutaconic acid, itaconic acid, acrylamide N-glycolic acid, and cinnamic acid. Etc. Of these, (meth) acrylic acid is preferably used.

  Examples of amino group-containing monomers include t-butylaminoethyl (meth) acrylate, ethylaminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, dimethylaminoethylacrylamide, dimethylacrylamide, and the like. Is mentioned. Among these, dimethylaminoethyl (meth) acrylate, dimethylaminopropylacrylamide, dimethylacrylamide, diethylaminoethyl are excellent in copolymerizability with other monomers and the effect of promoting crosslinking, and also in terms of availability as raw materials. (Meth) acrylate is preferred.

  Examples of the acetoacetyl group-containing monomer include 2- (acetoacetoxy) ethyl (meth) acrylate and allyl acetoacetate.

  Examples of the isocyanate group-containing monomer include 2-acryloyloxyethyl isocyanate, 2-methacryloyloxyethyl isocyanate, and alkylene oxide adducts thereof.

Examples of the glycidyl group-containing monomer include glycidyl (meth) acrylate, allyl glycidyl (meth) acrylate, and the like.
These functional group-containing ethylenically unsaturated monomers (a2) may be used alone or in combination of two or more.

The content of the functional group-containing ethylenically unsaturated monomer (a2) is preferably from 0.01 to 10% by weight, particularly from 0.05 to 7.5% by weight, more preferably from the entire polymerization component. It is preferably 0.05 to 5% by weight, particularly preferably 0.1 to 4% by weight.
If the content is too small, the reactivity with the crosslinking agent tends to decrease, or the crosslinking density tends to decrease and the cohesive strength tends to decrease. If the content is too large, the moisture permeability tends to increase and the water vapor barrier property tends to decrease.

  In the present invention, other copolymerizable ethylenically unsaturated monomer (a3) may be further contained as a polymerization component as required.

Examples of the ethylenically unsaturated monomer (a3) include:
Isobornyl (meth) acrylate, cyclohexyl (meth) acrylate, dicyclopentanyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, dicyclopentanyloxyethyl (meth) acrylate, Alicyclic (meth) acrylic acid alkyl ester monomers such as 2-adamantyl (meth) acrylate;
Aromatic (meth) acrylates such as benzyl (meth) acrylate, phenoxyethyl (meth) acrylate, nonylphenoxypolyethylene glycol acrylate, naphthalene (meth) acrylate, anthracene (meth) acrylate; tetramethylpiperidyl (meth) acrylate, penta Piperidyl ring-containing (meth) acrylic acid esters such as methylpiperidyl (meth) acrylate;
Fluorine-containing (meth) acrylic acid ester such as 2,2,2-trifluoroethyl (meth) acrylate;
2-methoxyethyl (meth) acrylate, 3-methoxyethyl (meth) acrylate, methoxydiethylene glycol (meth) acrylate, N-vinylcaprolactam, (meth) acryloylmorpholine, (meth) acrylamide, diacetone acrylamide, N- (meth) ) Acrylamide methyltrimethylammonium chloride, allyltrimethylammonium chloride, dimethylallyl vinyl ketone, N-vinyl pyrrolidone, vinyl propionate, vinyl stearate, vinyl chloride, vinylidene chloride, vinyl acetate, styrene and the like.

  For high molecular weight purposes, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate Polyfunctional monomers such as divinylbenzene can be used in combination.

  The content of the other copolymerizable ethylenically unsaturated monomer (a3) is preferably 0.1 to 40% by weight, particularly 0.1 to 20% by weight, based on the whole polymerization component. Is preferably 0.1 to 10% by weight, more preferably 0.1 to 5% by weight. If the content is too large, the water vapor barrier property tends to decrease.

  In the present invention, a (meth) acrylic acid alkyl ester having an alkyl group having less than 12 carbon atoms may be contained as a polymerization component within a range not impairing the object of the present invention.

  The acrylic resin (A) used in the present invention is produced by a method well known to those skilled in the art such as blending the above polymerization components in a predetermined ratio and radical polymerization in an organic solvent.

  Examples of the organic solvent used for the polymerization include aromatic hydrocarbons such as toluene and xylene, esters such as ethyl acetate and butyl acetate, aliphatic alcohols such as n-propyl alcohol and iso-propyl alcohol, acetone, and the like. , Ketones such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone.

  Examples of the polymerization initiator used for such radical polymerization include 2,2′-azobisisobutyronitrile, 2,2′-azobis-2-methylbutyronitrile, which are ordinary radical polymerization initiators, Azo initiators such as 4,4′-azobis (4-cyanovaleric acid), 2,2′-azobis (methylpropionic acid), benzoyl peroxide, laurolyl peroxide, di-t-butyl peroxide, cumene Examples thereof include organic peroxides such as hydroperoxide, which can be appropriately selected according to the monomer used. These solvents are used alone or in combination of two or more.

  In the present invention, the weight average molecular weight of the acrylic resin (A) is usually preferably from 50,000 to 3,000,000, more preferably from 60,000 to 2,500,000, still more preferably from 100,000 to 2,000,000, particularly preferably from 100,000 to 1.5 million. If the weight average molecular weight is too small, the cohesive force tends to decrease, and if the weight average molecular weight is too large, the solution viscosity tends to be too high.

  The degree of dispersion (weight average molecular weight / number average molecular weight) of the acrylic resin (A) is preferably 30 or less, particularly preferably 15 or less, and more preferably 8 or less. If the degree of dispersion is too high, the cohesive force tends to decrease. The lower limit of the degree of dispersion is usually 2.

In addition, said weight average molecular weight is a weight average molecular weight by standard polystyrene molecular weight conversion, and it is a column in a high performance liquid chromatography (The Japan Waters company, "Waters 2695 (main body)" and "Waters 2414 (detector)"). : Shodex GPC KF-806L (exclusion limit molecular weight: 2 × 10 ⁷ , separation range: 100 to 2 × 10 ⁷ , theoretical plate number: 10,000 plates / piece, filler material: styrene-divinylbenzene copolymer, filler The number average molecular weight can also be measured by the same method. The degree of dispersion is determined from the weight average molecular weight and the number average molecular weight.

  The glass transition temperature (Tg) of the acrylic resin (A) is preferably −100 to 0 ° C., particularly preferably −80 to −5 ° C., particularly preferably −70 to −10 ° C. If the glass transition temperature is too low, the heat resistance tends to decrease, and if it is too high, the adhesion tends to decrease.

The glass transition temperature is calculated from the following Fox equation.
1 / Tg = w1 / Tg1 + w2 / Tg2 + ... Wk / Tgk
Where Tg is the glass transition temperature of the copolymer, Tg1, Tg2,... Tgk is the Tg of the homopolymer of each monomer component, w1, w2,. ... Wk represents the molar fraction of each monomer component, and w1 + w2 +... Wk = 1.

  Thus, the acrylic resin (A) used in the present invention is obtained.

Next, the crosslinking agent (B) used in the present invention will be described.
Such a crosslinking agent (B) may be any one containing an alicyclic structure and an isocyanurate skeleton. Hereinafter, the crosslinking agent containing an alicyclic structure and an isocyanurate skeleton may be referred to as “crosslinking agent (B)”.

Examples of the alicyclic structure include cyclopropane ring, cyclobutane ring, cyclopentane ring, cyclohexane ring, cycloheptane ring, cyclononane ring, cyclooctane ring, bicyclohexane ring, tricyclohexane ring, and tricyclopentane ring. However, among these, a cyclohexane ring is preferable in terms of the chemical stability of the alicyclic skeleton and the availability as a raw material.
Further, the number of alicyclic structures contained in the crosslinking agent (B) is preferably 1 to 15, particularly preferably 2 to 10, and more preferably 3 to 7. When the content is too large, the reactivity with the functional group in the polymer is lowered, and aging tends to take time.

  Specific examples of the crosslinking agent (B) include an isocyanurate form of isophorone diisocyanate (Degussa; trade name “VESTANATE T1890 / 100”), and an isocyanurate form of hydrogenated xylylene diisocyanate (trade name, Mitsui Chemicals). “Takenate D-127N” and the like. Among these, an isocyanurate of isophorone diisocyanate is preferably used because it tends to improve cohesion and compatibility with the polymer (A).

  These crosslinking agents (B) may be used independently and may use 2 or more types together.

  The molecular weight of the crosslinking agent (B) is preferably 100 to 5,000, more preferably 200 to 3,000, and particularly preferably 400 to 1,500. If the molecular weight is too large, the reactivity tends to decrease and time is required for aging. If the molecular weight is too small, the reactivity increases too much and handling tends to be difficult.

The content of the crosslinking agent (B) is preferably 0.001 to 20 parts by weight, particularly preferably 0.005 to 10 parts by weight, and more preferably 100 parts by weight of the acrylic resin (A). Preferably it is 0.01-5 weight part.
If the content of the cross-linking agent (B) is too small, the cohesive force tends to decrease, and if too large, the adhesive force tends to decrease.

  Furthermore, the pressure-sensitive adhesive composition of the present invention includes an antistatic agent, other acrylic pressure-sensitive adhesives, other pressure-sensitive adhesives, urethane resin, rosin, rosin ester, and hydrogenated rosin ester as long as the effects of the present invention are not impaired. , Phenolic resins, aromatic modified terpene resins, aliphatic petroleum resins, alicyclic petroleum resins, styrene resins, xylene resins, tackifiers, colorants, fillers, antioxidants, anti-aging agents, Various additives such as an ultraviolet absorber can be blended. In addition to the above additives, a small amount of impurities and the like contained in the raw materials for producing the constituent components of the pressure-sensitive adhesive composition may be contained. What is necessary is just to set these addition amounts suitably so that the desired physical property may be obtained.

In addition, in order to use the adhesive composition of this invention for transparent electrode films, such as an ITO film, ITO glass, Cu mesh, Ag, etc., since corrosion resistance is needed, an adhesive composition is substantial. It is preferable that no acid is contained.
The phrase “substantially free of acid” means that no acid group-containing monomer is used as a copolymerization component of the acrylic resin (A), and the acid value of the entire pressure-sensitive adhesive composition is preferably 5 mgKOH / g or less, particularly preferably. It means 1 mgKOH / g or less, more preferably 0.1 mgKOH / g.

Moreover, since it is preferable not to contact a water | moisture content with respect to the transparent electrode using the metal which is easy to cause a migration, especially Cu mesh or Ag, it is desirable for an adhesive to have a low water vapor transmission rate.
The water vapor transmission rate (whole adhesive composition) is preferably 250 g / m ² · day (50 μm) or less, and more preferably 200 g / m ² · day (50 μm) or less.

  The gel fraction of the pressure-sensitive adhesive obtained by crosslinking the pressure-sensitive adhesive composition of the present invention is usually 20 to 98%, preferably 30 to 95%, particularly preferably 50 to 90%. If the gel fraction is too low, the cohesive force tends to decrease, and if it is too high, the adhesive force tends to decrease.

  In addition, in adjusting the gel fraction of an adhesive to the said range, it is achieved by adjusting the quantity of a crosslinking agent, adjusting the composition ratio of the hydroxyl group in a composition, etc., for example. Moreover, since the gel fraction changes by each interaction, it is desirable to balance each ratio between the crosslinking agent and the functional group amount.

  The gel fraction is a measure of the degree of crosslinking, and is calculated, for example, by the following method. That is, a pressure-sensitive adhesive sheet (not provided with a separator) in which a pressure-sensitive adhesive layer is formed on a polymer sheet (for example, polyethylene terephthalate film or the like) as a base material is wrapped with a 200-mesh SUS wire mesh, and 23 in toluene. The weight percentage of the insoluble pressure-sensitive adhesive component immersed in the wire mesh at 24 ° C. for 24 hours is defined as the gel fraction. However, the weight of the substrate is subtracted.

  The haze of the pressure-sensitive adhesive obtained by crosslinking the pressure-sensitive adhesive composition of the present invention is preferably 1.0% or less, particularly preferably 0.5% or less. If the haze value is too high, the image tends to be unclear when used for display. The lower limit of the haze value is usually 0.00%.

  The total light transmittance of the pressure-sensitive adhesive obtained by crosslinking the pressure-sensitive adhesive composition of the present invention is preferably 80.0% or more, particularly preferably 90.0% or more. If the total light transmittance is too low, the image tends to be unclear when used for display. The upper limit of the haze value is usually 99.90%.

  Here, the above-mentioned total line transmittance and haze value are values measured using a haze meter based on JIS K7361-1.

  Next, a pressure-sensitive adhesive sheet can be produced by forming a pressure-sensitive adhesive layer using the pressure-sensitive adhesive composition of the present invention. That is, the pressure-sensitive adhesive sheet can be produced, for example, as follows.

  First, the pressure-sensitive adhesive composition is applied to one side or both sides of a supporting base material so as to have a predetermined thickness, and then heated and dried to form a pressure-sensitive adhesive layer. Next, a pressure-sensitive adhesive sheet can be produced by attaching a release sheet to the pressure-sensitive adhesive layer surface as necessary. In addition, the obtained pressure-sensitive adhesive sheet is subjected to an aging treatment as necessary, and then, when used, the release sheet is peeled from the pressure-sensitive adhesive layer and used. In this way, a pressure-sensitive adhesive sheet is obtained in which a pressure-sensitive adhesive layer is formed on one side or both sides of the support substrate, and a release sheet is provided on the pressure-sensitive adhesive layer surface as necessary.

  In the present invention, the “sheet” is not particularly distinguished from “film” or “tape”, and is described as meaning including these.

  Examples of the support substrate include metal foils such as aluminum, copper, and iron; polyester resins such as polyethylene naphthalate, polyethylene terephthalate, polybutylene terephthalate, polyethylene terephthalate / isophthalate copolymer; polyethylene, polypropylene, polymethyl Polyolefin resins such as pentene; Polyfluorinated ethylene resins such as polyvinyl fluoride, polyvinylidene fluoride, and polyfluorinated ethylene; Polyamides such as nylon 6, nylon 6, and 6; Polyvinyl chloride, polyvinyl chloride / vinyl acetate copolymer, Ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, vinyl polymers such as polyvinyl alcohol and vinylon; cellulose resins such as cellulose triacetate and cellophane; polymethyl methacrylate, polymeta Acrylic resins such as ethyl laurate, polyethyl acrylate, and polybutyl acrylate; synthetic resin films or sheets such as polystyrene, polycarbonate, polyarylate, polyimide, paper such as fine paper, glassine paper, glass fiber, natural fiber, A monolayer or a multilayer selected from synthetic fibers and the like can be mentioned. The thickness of the supporting substrate is usually 1 to 500 μm, preferably 5 to 300 μm.

Further, as the release sheet, for example, various synthetic resin sheets exemplified for the support substrate, paper, cloth, non-woven fabric and the like can be used.
Alternatively, the pressure-sensitive adhesive composition can be formed on a release sheet by forming the pressure-sensitive adhesive layer by applying the pressure-sensitive adhesive composition to the release sheet and drying by heating, and bonding the release sheet to the pressure-sensitive adhesive layer. it can.

  In coating the pressure-sensitive adhesive composition, it is preferable to dilute and apply the pressure-sensitive adhesive composition to a solvent. The dilution concentration is preferably 5 to 80% by weight, particularly preferably 10 to 70% by weight. . The solvent may be any solvent that dissolves the pressure-sensitive adhesive composition. Examples thereof include ester solvents such as methyl acetate, ethyl acetate, methyl acetoacetate, and ethyl acetoacetate, acetone, methyl ethyl ketone, and methyl isobutyl ketone. Ketone solvents, aromatic solvents such as toluene and xylene, and alcohol solvents such as methanol, ethanol and propyl alcohol can be used. Among these, ethyl acetate, methyl ethyl ketone, and toluene are preferably used from the viewpoints of solubility, drying property, price, and the like.

  In addition, the application method of the pressure-sensitive adhesive composition is not particularly limited as long as it is a general application method, and examples thereof include roll coating, die coating, gravure coating, comma coating, and screen printing. can give.

  And as said heat drying conditions, what is necessary is just to be able to dry an adhesive composition, for example, normally 50-150 degreeC, Preferably it is 60-130 degreeC, Usually about 1 to 10 minutes, Preferably it is 1 The condition is about 5 to 5 minutes.

  The above aging treatment is performed to balance the physical properties of the adhesive. As aging conditions, the temperature is usually room temperature (25 ° C. ± 5 ° C.) to 70 ° C., and the time is usually 1 day to 30 days. Specifically, for example, the treatment may be performed at 23 ° C. for 1 day to 20 days, at 40 ° C. for 1 day to 7 days, or the like.

  Furthermore, as for the thickness of the adhesive layer in the adhesive sheet obtained, 1-250 micrometers is preferable normally, More preferably, it is 5-200 micrometers, Most preferably, it is 10-150 micrometers. If the thickness of the pressure-sensitive adhesive layer is too thin, the physical properties of the adhesive tend to be difficult to stabilize, and if it is too thick, drying tends to be difficult and foaming tends to occur.

  Thus, although the thickness of the adhesive sheet obtained is set suitably according to a use, it is preferable to set to the range of 5-300 micrometers, for example.

  When using the pressure-sensitive adhesive sheet in the present invention, the types of adherends include, for example, articles having various metal surfaces; polyester resins such as polyethylene naphthalate, polyethylene terephthalate, polybutylene terephthalate, polyethylene terephthalate / isophthalate copolymer; Polyolefin resins such as polyethylene, polypropylene, and polymethylpentene; Polyfluorinated ethylene resins such as polyvinyl fluoride, polyvinylidene fluoride, and polyfluorinated ethylene; Polyamides such as nylon 6, nylon 6, and 6; Polyvinyl chloride, Polyvinyl chloride / Vinyl acetate copolymers, ethylene-vinyl acetate copolymers, ethylene-vinyl alcohol copolymers, vinyl polymers such as polyvinyl alcohol and vinylon; cellulose resins such as cellulose triacetate and cellophane; Methyl methacrylate, polyethyl methacrylate, polyethyl acrylate, acrylic resins such as polybutyl acrylate; polystyrene, polycarbonate, polyarylate, synthetic resin films such as polyimide, sheet or plate and the like.

  The article having the metal surface has a metal surface, and the pressure-sensitive adhesive sheet is directly bonded to the metal surface at least partially or entirely. In an article having such a metal surface, the adherend to which the pressure-sensitive adhesive sheet is bonded (sometimes referred to as “metal face-containing adherend”) has at least a partial metal surface. There is no particular limitation. In such a metal surface-containing adherend, the part where the metal surface is formed is not particularly limited as long as it is a part where the adhesive sheet can be directly attached, and may be an outer surface, Further, it may be an inner surface or the like. When a plurality of metal surfaces are formed on one metal surface-containing adherend, these plurality of metal surfaces may be surfaces formed of the same metal material or formed of different metal materials. It may be a surface.

  The metal surface in the metal surface-containing adherend may be the surface of a metal surface-containing adherend formed of a metal material, or formed on the surface of a substrate (or structure) formed of various materials. It may be the surface of the metal layer (particularly, the surface of the metal thin film layer). In any case, the metal surface may be a surface made of a metal material.

  The metal layer such as the metal thin film layer can be formed at a predetermined site on the surface of the base material (or structure) made of various materials. In such a metal layer, the thickness of the metal thin film layer can be appropriately selected according to the type of the metal surface-containing adherend, and may be, for example, 0.1 μm or more. The upper limit of the thickness of the metal thin film layer is not particularly limited as long as it is generally regarded as a thin film layer.

  Examples of the metal material for forming the metal surface include a metal material made of a single metal such as aluminum, silver, gold, copper, iron, titanium, platinum, nickel; a gold alloy (for example, a gold-copper alloy), Copper alloys (eg, copper-zinc alloys (brass), copper-aluminum alloys, etc.), aluminum alloys (eg, aluminum-molybdenum alloys, aluminum-tantalum alloys, aluminum-cobalt alloys, aluminum-chromium alloys, aluminum-titanium alloys, Aluminum-platinum alloy etc.), nickel alloys (for example, nickel-chromium alloy, copper-nickel alloy, zinc-nickel alloy etc.), metal materials by various alloys such as tin alloy, stainless steel and the like. These metal materials can be used alone or in combination of two or more.

  The metal material may be a metal material containing only a metal element, or a metal material containing a non-metal element together with a metal element [eg, metal oxide, hydroxide, halide (chloride, etc.) Metal compounds such as oxo acid salts (nitrates, sulfates, phosphates, carbonates, etc.), for example, ITO (indium tin oxide), ZnO, (zinc oxide), SnO (tin oxide) ), CTO (cadmium tin oxide) and the like.

  Specifically, examples of the metal surface-containing adherend include an optical product having a transparent conductive film laminate provided with a transparent conductive film, or a member for constituting the optical product. Examples of the optical product having the transparent conductive layer include an electronic display (such as a touch panel). Examples thereof include an optical product having an electromagnetic wave shielding layer formed of a metal thin film layer, or a member for constituting the optical product. Examples of the optical product having the electromagnetic wave shielding layer include optical devices such as an electronic display (plasma display and the like), optically recordable discs (optical recording discs) such as a digital universal disc, and the like.

  Thus, the pressure-sensitive adhesive and pressure-sensitive adhesive sheet of the present invention are used for bonding and information labels used for bonding to various electronic members such as computers, mobile phones and thin-screen TVs, precision electronic members, pressure-sensitive adhesives for fixing electronic members, and organic EL. It is useful as an adhesive for sealing elements.

  The pressure-sensitive adhesive composition of the present invention is used as an organic solvent-containing type pressure-sensitive adhesive composition, and is cured by heat in the presence of a crosslinking agent to form a pressure-sensitive adhesive. (Approx. 3 N / 25 mm or more), and is suitably used as an adhesive that can be bonded to an adherend over a medium to long period (several months to several years).

EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further more concretely, this invention is not limited to a following example, unless the summary is exceeded.
In the examples, “parts” and “%” mean weight basis.

<Example of production of acrylic resin (A)>
<Manufacture of acrylic resin (A-1)>
In a 4-neck round bottom flask equipped with a reflux condenser, a stirrer, a nitrogen gas inlet and a thermometer, 81.6 parts of isostearyl acrylate (a1), 15 parts of isotridecyl methacrylate (a1), 4-hydroxy While charging 3 parts of butyl acrylate (a2), 0.4 part of dimethylaminopropylacrylamide (a2) and 30 parts of acetone, 0.03 part of azobisisobutyronitrile (AIBN) as a polymerization initiator, adding AIBN appropriately After reacting at the reflux temperature for 8 hours, diluted with toluene to obtain an acrylic resin (A-1) solution (weight average molecular weight 123,000, dispersity 2.10, solid content concentration 53.0%, viscosity 2,000 mPa · s (25 ° C.)).

<Manufacture of acrylic resin (A-2)>
In a 4-neck round bottom flask equipped with a reflux condenser, a stirrer, a nitrogen gas inlet and a thermometer, 98 parts of isostearyl acrylate (a1), 2 parts of 2-hydroxyethyl acrylate (a2), and 30 parts of acetone Then, 0.04 part of azobisisobutyronitrile (AIBN) was added as a polymerization initiator, reacted for 8 hours at reflux temperature while appropriately adding AIBN, and diluted with toluene to obtain an acrylic resin (A-2) solution. (Weight average molecular weight 30,000, dispersity 2.50, glass transition temperature -26 ° C., solid content concentration 49.5%, viscosity 2,500 mPa · s (25 ° C.)).

<Manufacture of acrylic resin (A-3)>
In a 4-neck round bottom flask equipped with a reflux condenser, a stirrer, a nitrogen gas inlet and a thermometer, 71.4 parts of isostearyl acrylate (a1), 25 parts of isotridecyl methacrylate (a1), 4-hydroxy 1.8 parts of butyl acrylate (a2), 0.3 part of dimethylaminopropylacrylamide (a2), 1.5 parts of acryloylmorpholine (a3) and 30 parts of acetone, azobisisobutyronitrile (AIBN) as a polymerization initiator 0.03 part was charged, and AIBN was added as appropriate, the reaction was carried out at reflux temperature for 8 hours, and then diluted with toluene to prepare an acrylic resin (A-3) solution (weight average molecular weight 219,000, dispersity 2.44, A solid content concentration of 52.8% and a viscosity of 4,400 mPa · s (25 ° C.)) were obtained.

<Manufacture of acrylic resin (A-4)>
In a 4-neck round bottom flask equipped with a reflux condenser, a stirrer, a nitrogen gas inlet and a thermometer, 15 parts of isostearyl acrylate (a1), 82.9 parts of lauryl methacrylate (a1), 4-hydroxybutyl acrylate (A2) 1.8 parts, dimethylaminopropylacrylamide (a2) 0.3 parts, acetone 33 parts, ethyl acetate 13 parts, azobisisobutyronitrile (AIBN) 0.03 parts as a polymerization initiator, After appropriately reacting at reflux temperature for 8 hours while adding AIBN as appropriate, it was diluted with toluene and diluted with an acrylic resin (A-4) solution (glass transition temperature-58.2 ° C., solid content concentration 50.3%, viscosity 6, 700 mPa · s (25 ° C.)) was obtained.

<Manufacture of acrylic resin (A'-1)>
In a 4-neck round bottom flask equipped with a reflux condenser, a stirrer, a nitrogen gas inlet and a thermometer, 98 parts of 2-ethylhexyl acrylate, 2 parts of 2-hydroxyethyl acrylate (a2), and 45 parts of ethyl acetate, polymerization Charge 0.03 part of azobisisobutyronitrile (AIBN) as an initiator, react for 8 hours at reflux temperature while adding AIBN appropriately, and then dilute with ethyl acetate to obtain an acrylic resin (A′-1) solution (Glass transition temperature-69.1 ° C, solid content concentration 56.0%, viscosity 2,500 mPa · s (25 ° C)).

<Manufacture of acrylic resin (A'-2)>
In a four-necked round bottom flask equipped with a reflux condenser, a stirrer, a nitrogen gas inlet and a thermometer, 18 parts of isostearyl acrylate (a1), 35 parts of lauryl methacrylate (a1), 32 parts of 2-ethylhexyl acrylate, 2 -15 parts of hydroxyethyl acrylate (a2), 11 parts of ethyl acetate, 20 parts of acetone and 9 parts of methyl ethyl ketone, 0.06 part of azobisisobutyronitrile (AIBN) as a polymerization initiator were added, and refluxed while appropriately adding AIBN After reacting at temperature for 8 hours, diluted with ethyl acetate to obtain an acrylic resin (A′-2) solution (weight average molecular weight 791,000, dispersity 4.86, glass transition temperature−53.0 ° C., solid content concentration) 52.4% and a viscosity of 12,000 mPa · s (25 ° C.)).

<Crosslinking agent>
The following were prepared as a crosslinking agent (B).
・ (B-1)
Isophorone diisocyanate isocyanurate (Degussa; trade name “Vestanat T1890 / 100”)
・ (B'-1)
Trimethylolpropane adduct of isophorone diisocyanate (Mitsui Chemicals, trade name “Takenate D140”)
・ (B'-2)
Isocyanurate of hexamethylene diisocyanate (Nippon Polyurethane Industry Co., Ltd .; trade name “Coronate HX”)
・ (B'-3)
Trimethylolpropane adduct of hydrogenated xylylene diisocyanate (Mitsui Chemicals, trade name “Takenate D120”)
・ (B'-4)
Trimethylolpropane adduct of hexamethylene diisocyanate (Mitsui Chemicals, trade name “Takenate D160”)
・ (B'-5)
Trimethylolpropane adduct of tolylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd .; trade name “Coronate L55E”)

<Examples 1-3, Comparative Examples 1-9>
The said acrylic resin (A) and the crosslinking agent (B) were mix | blended in the ratio shown in following Table 1, and the adhesive composition was prepared by adjusting solid content concentration to 30% using toluene.

  The following evaluation was performed using the pressure-sensitive adhesive compositions obtained in the above Examples and Comparative Examples. These results are also shown in Table 1 below.

  The pressure-sensitive adhesive composition solution was applied to a light release PET film (Mitsui Chemicals, Inc .: Lumirror SP01-38BU) so that the thickness after drying was 50 μm, dried at 100 ° C. for 3 minutes, and then subjected to heavy release PET ( Mitsui Chemicals Tosero Co., Ltd .: Lumirror SP03-38BU) was bonded and aged at 40 ° C. for 3 to 7 days to obtain a substrate-less double-sided pressure-sensitive adhesive sheet.

[Water vapor barrier]
The light release PET of the base material-less double-sided pressure-sensitive adhesive sheet was peeled off and bonded to a SUS mesh (400 mesh) to obtain a moisture permeability measurement sample.
The moisture permeability measurement was performed by a cup method according to JIS Z 0208, and the adhesive layer bonded to the mesh was placed on the outside air side and evaluated in an atmosphere of 40 ° C. and 90% RH. The evaluation criteria are as follows.
(Evaluation)
Greater than ○ ··· 250g / m ² · day or less × ··· 250g / m ² · day

〔transparency〕
[Total light transmittance] and [Haze]
The release sheet on one side is peeled off from the pressure-sensitive adhesive layer of the baseless double-sided pressure-sensitive adhesive sheet, and the pressure-sensitive adhesive layer side is bonded to an alkali-free glass plate (Corning Corp., Eagle XG), followed by autoclaving (50 ° C. , 0.5 MPa, 20 minutes), and the other release sheet was peeled off to obtain an alkali-free glass plate with an adhesive layer.
The diffuse transmittance and total light transmittance of the alkali-free glass plate with the pressure-sensitive adhesive layer were measured using HAZE MATER NDH2000 (manufactured by Nippon Denshoku Industries Co., Ltd.). This machine complies with JISK7361-1.
The obtained diffuse transmittance and total light transmittance were substituted into the following formula to calculate haze and evaluated according to the following criteria.
Haze (%) = (diffuse transmittance / total light transmittance) × 100
(Evaluation)
○ ・ ・ ・ 1.0% or less × ・ ・ ・ greater than 1.0%

〔Adhesive force〕
The pressure-sensitive adhesive composition solution was applied to a heavy release PET film (Mitsui Chemicals, Inc .: Lumirror SP03-38BU) so that the thickness after drying was 50 μm, dried at 100 ° C. for 3 minutes, and then a light release PET film. The substrate-less double-sided pressure-sensitive adhesive sheet was obtained by pasting to Mitsui Chemicals Tosero Co., Ltd .: Lumirror SP01-38BU and aging at 40 ° C. for 3 days.
The light release sheet on one side is peeled off from the pressure-sensitive adhesive layer of the obtained substrate-less double-sided pressure-sensitive adhesive sheet, and pressed onto a 125 μm thick easy-adhesive PET (polyethylene terephthalate) film to form a PET film with a pressure-sensitive adhesive layer. After cutting the sheet into 25 mm × 100 mm, the heavy release PET film is peeled off, and this is used as an adherend to non-alkali glass (“Eagle XG” manufactured by Corning) in a 2 kg rubber atmosphere at 23 ° C. and 50% relative humidity. A test piece was prepared by pressure bonding by reciprocating twice using a roller. The test piece was allowed to stand for 30 minutes in the same atmosphere, and then subjected to a 180 ° peel test at a peel rate of 0.3 m / min to measure the adhesive strength (N / 25 mm). The evaluation criteria are as follows.
(Evaluation)
○ ・ ・ ・ 5N / 25mm or more × ・ ・ ・ less than 5N / 25mm

[Gel fraction]
The pressure-sensitive adhesive composition solution was applied to a heavy release PET film (Mitsui Chemicals, Inc .: Lumirror SP03-38BU) so that the thickness after drying was 50 μm, dried at 100 ° C. for 3 minutes, and then a light release PET film. The adhesive sheet was obtained by bonding to (Mitsui Chemicals Tosero Co., Ltd .: Lumirror SP01-38BU) and aging at 40 ° C. for 3 days.
After the obtained pressure-sensitive adhesive sheet is cut into 40 × 40 mm, the lightly peeled PET film is peeled off, the pressure-sensitive adhesive layer side is bonded to a 50 × 100 mm SUS mesh sheet (200 mesh), and then the heavyly peeled PET film is peeled off. After wrapping the sample from the center with respect to the longitudinal direction of the SUS mesh sheet and immersing it in a sealed container containing 250 g of toluene, the gel fraction ( %).

From the above evaluation results, acrylic resin (A) obtained by polymerizing a polymerization component containing 60% by weight or more of (meth) acrylic acid alkyl ester monomer (a1) having 12 or more carbon atoms in the alkyl group, and alicyclic ring In the pressure-sensitive adhesives of Examples 1 to 3 obtained from the pressure-sensitive adhesive composition containing the crosslinking agent (B) that is an isocyanurate body having a skeleton, the pressure-sensitive adhesive force is excellent, and gas barrier properties, in particular, water vapor barrier properties, It turns out that it is the adhesive which was excellent in the transparency of the adhesive layer with a good balance.
On the other hand, the pressure-sensitive adhesives obtained from the pressure-sensitive adhesive compositions of Comparative Examples 1 to 6 using a crosslinking agent different from the specific structure of the present invention are inferior in transparency and have a low content of the long-chain monomer component. It turns out that the adhesive obtained from the adhesive composition of Comparative Examples 7-9 using the acrylic resin which does not contain acrylic resin or a long-chain monomer component is inferior to water vapor | steam barrier property.

  The pressure-sensitive adhesive composition of the present invention, and the pressure-sensitive adhesive and pressure-sensitive adhesive sheet using the same are used for bonding, information labels, and electronic members used for bonding to various electronic members such as computers, mobile phones, and thin-screen TVs, and precision electronic members. It is useful as a fixing adhesive, an organic EL element sealing adhesive, and the like.

Claims (8)

Contains an acrylic resin (A) obtained by polymerizing a polymerization component containing 60% by weight or more of a (meth) acrylic acid alkyl ester monomer (a1) having 12 or more carbon atoms in the alkyl group, and a crosslinking agent (B) An adhesive composition, wherein the crosslinking agent (B) is a crosslinking agent containing an alicyclic structure and an isocyanurate skeleton. The pressure-sensitive adhesive composition according to claim 1, wherein the polymerization component comprises a hydroxyl group-containing monomer. The pressure-sensitive adhesive composition according to claim 1 or 2, wherein the polymerization component contains an amino group-containing monomer. The pressure-sensitive adhesive composition according to claim 1, wherein the crosslinking agent (B) is an isocyanurate of isophorone diisocyanate. Content of a crosslinking agent (B) is 0.001-20 weight part with respect to 100 weight part of acrylic resin (A), The adhesive composition in any one of Claims 1-4 characterized by the above-mentioned. The pressure-sensitive adhesive composition according to any one of claims 1 to 5, wherein the acid value is 5 mgKOH / g or less . A pressure-sensitive adhesive composition obtained by curing the pressure-sensitive adhesive composition according to claim 1. A pressure-sensitive adhesive sheet comprising a pressure-sensitive adhesive layer comprising the pressure-sensitive adhesive according to claim 7.