JP5948509B2 - Adhesive composition, adhesive and adhesive sheet - Google Patents

Description

  The present invention relates to a pressure-sensitive adhesive composition suitable for adhesion between a transparent conductive film and glass, a pressure-sensitive adhesive (a material obtained by crosslinking a pressure-sensitive adhesive composition), and a pressure-sensitive adhesive sheet.

  In various mobile electronic devices such as smartphones and tablet terminals in recent years, a capacitive touch panel is often used as a display.

  There are various configurations of capacitive touch panels. As a typical example, a display module such as a liquid crystal module, and a first film sensor laminated thereon via a first adhesive layer The structure provided with the 2nd film sensor laminated | stacked through the 2nd adhesive layer on it and the cover glass laminated | stacked through the 3rd adhesive layer on it is mentioned.

  The film sensor is usually composed of a base film and a transparent conductive film made of patterned tin-doped indium oxide (ITO). That is, the third pressure-sensitive adhesive layer bonds the transparent conductive film and the cover glass. Therefore, the pressure-sensitive adhesive layer needs to have a predetermined adhesive force for both the transparent conductive film and the cover glass.

  Here, Patent Document 1 discloses an adhesive composition for attaching an ITO electrode to the surface of a glass substrate. Specifically, it comprises (A) a (meth) acrylic polymer having a functional group other than an acidic group and a (meth) acrylic polymer having a weight average molecular weight of 50,000 to 150,000, and (B) an isocyanate-based crosslinking agent, and (meth) acrylic. In 100 parts by weight of the polymer (A), (a-1) alkoxyalkyl (meth) acrylate and / or alkoxyalkylene glycol (meth) acrylate is copolymerized in an amount in the range of 50 to 99.8 parts by weight, (A-2) the monomer having a hydroxyl group is copolymerized in an amount in the range of 0.1 to 10 parts by weight, and (a-3) the nitrogen-containing monomer is copolymerized in an amount in the range of 0.1 to 5 parts by weight. (A-4) alkyl (meth) acrylate is copolymerized in an amount in the range of 0 to 49.8 parts by weight, and (A) (meth) acrylic monomer has a crosslinked structure of (B) isocyanate compound. Formed A pressure-sensitive adhesive composition for a conductive film is disclosed.

JP2013-142121A

  However, the invention described in Patent Document 1 provides a pressure-sensitive adhesive composition for a conductive film that is excellent in heat-resistant foaming resistance and moisture-heat stability (whitening resistance) and has no corrosiveness to metals or metal oxides. It was aimed and the said adhesive composition did not necessarily exhibit sufficient adhesive force with respect to both a transparent conductive film and glass.

  This invention is made | formed in view of the above actual conditions, and provides the adhesive composition, adhesive, and adhesive sheet which exhibit sufficient adhesive force with respect to a transparent conductive film and at least glass. With the goal.

  In order to achieve the above object, first, the present invention provides a (meth) acrylic acid ester polymer containing a monomer having an alicyclic structure and a monomer having a nitrogen atom as monomer units constituting the polymer. A pressure-sensitive adhesive composition is provided (Invention 1).

  According to the said invention (invention 1), the adhesive obtained by the separate action | operation and interaction of the monomer which has an alicyclic structure which comprises a (meth) acrylic acid ester polymer, and the monomer which has a nitrogen atom, It exhibits strong adhesion to transparent conductive films, particularly transparent conductive films made of tin-doped indium oxide (ITO), glass and plastic.

  In the said invention (invention 1), the said (meth) acrylic acid ester polymer contains 3-20 mass% of monomers which have the said alicyclic structure as a monomer unit which comprises the said polymer, The said nitrogen atom is contained. It is preferable to contain 2 to 20% by mass of the monomer (Invention 2).

  In the said invention (invention 1 and 2), the said (meth) acrylic acid ester polymer is a monomer unit which comprises the said polymer, and the monomer which has the said alicyclic structure, and the monomer which has the said nitrogen atom in total 5 to 5 It is preferable to contain 40 mass% (Invention 3).

  In the said invention (invention 1-3), it is preferable that the said alicyclic structure contains an isobornyl skeleton (invention 4).

  In the said invention (invention 1-4), it is preferable that the monomer which has the said nitrogen atom has a nitrogen-containing heterocyclic ring (invention 5).

  In the said invention (invention 1-5), it is preferable that the said adhesive composition contains a crosslinking agent further (invention 6).

  In the said invention (invention 6), it is preferable that the said (meth) acrylic acid ester polymer contains the monomer which has a functional group which reacts with the said crosslinking agent as a monomer unit which comprises the said polymer (invention 7). .

  In the said invention (invention 1-7), it is preferable that the said (meth) acrylic acid ester polymer does not contain the monomer which has a carboxyl group as a monomer unit which comprises the said polymer (invention 8).

  2ndly, this invention provides the adhesive formed by hardening | curing the said adhesive composition (invention 1-8) (invention 9).

  Thirdly, the present invention includes two release sheets, and an adhesive layer sandwiched between the release sheets so as to be in contact with the release surfaces of the two release sheets, and the adhesive layer is the adhesive ( An adhesive sheet comprising the invention 9) is provided (invention 10).

  In the said invention (invention 10), it is preferable that the said adhesive sheet is used for adhesion | attachment with a transparent conductive film, glass, or a plastic (invention 11).

  The pressure-sensitive adhesive composition, the pressure-sensitive adhesive, and the pressure-sensitive adhesive layer of the pressure-sensitive adhesive sheet according to the present invention exhibit excellent adhesive strength to the transparent conductive film, glass and plastic.

It is sectional drawing of the adhesive sheet which concerns on one Embodiment of this invention. It is sectional drawing which shows one structural example of a touchscreen.

Hereinafter, embodiments of the present invention will be described.
[Adhesive composition]
The pressure-sensitive adhesive composition according to the present embodiment (hereinafter referred to as “pressure-sensitive adhesive composition P”) includes, as monomer units constituting the polymer, a monomer having an alicyclic structure (alicyclic structure-containing monomer), nitrogen, and the like. A (meth) acrylic acid ester polymer (hereinafter referred to as “(meth) acrylic acid ester polymer (A)”) containing a monomer having an atom (nitrogen atom-containing monomer), and preferably a crosslinking agent ( B). In this specification, (meth) acrylic acid ester means both acrylic acid ester and methacrylic acid ester. The same applies to other similar terms. Further, the “polymer” includes the concept of “copolymer”.

  In the pressure-sensitive adhesive composition P according to this embodiment, the (meth) acrylic acid ester polymer (A) contains both an alicyclic structure-containing monomer and a nitrogen atom-containing monomer as monomer units constituting the polymer. By doing this, the resulting adhesive has a strong adhesion to transparent conductive films, particularly transparent conductive films made of tin-doped indium oxide (ITO), and glass and plastics, especially polycarbonate, polymethyl methacrylate, and other plastics. Demonstrate. It is considered that the alicyclic structure-containing monomer mainly contributes to the adhesive strength to the transparent conductive film, and the nitrogen atom-containing monomer mainly contributes to the adhesive strength to glass and plastic. In addition to this, by making a bulky alicyclic structure-containing monomer present in the polymer as a structural unit, the interval between the polymers can be widened, and the resulting adhesive can be made excellent in flexibility. . Thereby, an adhesive becomes what was excellent in the followable | trackability to the surface unevenness | corrugation of a to-be-adhered body. Furthermore, the presence of a nitrogen atom-containing monomer in the polymer as a constituent unit gives the adhesive a predetermined polarity, and it has an affinity for adherends having a certain degree of polarity, such as transparent conductive films and glass. It can be made excellent. As a result, it is presumed that the following pressure-sensitive properties and affinity properties are combined, and the resulting pressure-sensitive adhesive is excellent in adhesive strength even with respect to a transparent conductive film or glass.

(1) (Meth) acrylic acid ester polymer (A)
The alicyclic structure carbocyclic ring in the alicyclic structure-containing monomer contained in the (meth) acrylic acid ester polymer (A) as a monomer unit constituting the polymer may have a saturated structure, It may have an unsaturated bond. The alicyclic structure may be a monocyclic alicyclic structure or a polycyclic alicyclic structure such as a bicyclic ring or a tricyclic ring. The alicyclic structure preferably has 5 to 20 carbon atoms, particularly preferably 6 to 15 carbon atoms, and more preferably 7 to 12 carbon atoms.

  Examples of the alicyclic structure include a cyclohexyl skeleton, dicyclopentadiene skeleton, adamantane skeleton, isobornyl skeleton, cycloalkane skeleton (cycloheptane skeleton, cyclooctane skeleton, cyclononane skeleton, cyclodecane skeleton, cycloundecane skeleton, cyclododecane skeleton, etc.) , Cycloalkene skeleton (cycloheptene skeleton, cyclooctene skeleton, etc.), norbornene skeleton, norbornadiene skeleton, polycyclic skeleton (cuban skeleton, basketetane skeleton, Hausan skeleton, etc.), spiro skeleton, etc. Those containing an isobornyl skeleton exhibiting excellent adhesive strength are preferred.

  As the alicyclic structure-containing monomer, a (meth) acrylic acid ester monomer containing the above skeleton is preferable. Specifically, cyclohexyl (meth) acrylate, dicyclopentanyl (meth) acrylate, (meth) Examples include adamantyl acrylate, isobornyl (meth) acrylate, dicyclopentenyl (meth) acrylate, and dicyclopentenyloxyethyl (meth) acrylate. Among them, (meth) acrylic acid that exhibits better adhesion Isobornyl is preferred. These may be used individually by 1 type and may be used in combination of 2 or more type.

  The (meth) acrylic acid ester polymer (A) preferably contains 3 to 20% by mass of the alicyclic structure-containing monomer as the monomer unit constituting the polymer, and particularly 6 to 18% by mass. Is preferable, and it is more preferable to contain 9-15 mass%. When the content of the alicyclic structure-containing monomer is 3% by mass or more, the obtained pressure-sensitive adhesive has sufficient adhesive strength (especially excellent adhesive strength to the transparent conductive film) to the transparent conductive film, glass and plastic. Can be demonstrated. Further, when the content of the alicyclic structure-containing monomer is 20% by mass or less, the content of other monomer components can be ensured and excellent adhesive strength can be sufficiently exhibited.

  The nitrogen atom-containing monomer contained in the (meth) acrylic acid ester polymer (A) as a monomer unit constituting the polymer includes a monomer having an amino group, a monomer having an amide group, a monomer having a nitrogen-containing heterocyclic ring, etc. Among them, a monomer having a nitrogen-containing heterocyclic ring is preferable.

  Examples of the monomer having a nitrogen-containing heterocyclic ring include N- (meth) acryloylmorpholine, N-vinyl-2-pyrrolidone, N- (meth) acryloylpyrrolidone, N- (meth) acryloylpiperidine, N- (meth) acryloyl. Pyrrolidine, N- (meth) acryloylaziridine, aziridinylethyl (meth) acrylate, 2-vinylpyridine, 4-vinylpyridine, 2-vinylpyrazine, 1-vinylimidazole, N-vinylcarbazole, N-vinylphthalimide, etc. Among them, N- (meth) acryloylmorpholine exhibiting more excellent adhesive strength is preferable, and N-acryloylmorpholine is particularly preferable.

Examples of nitrogen atom-containing monomers include (meth) acrylamide, N-methyl (meth) acrylamide, N-methylol (meth) acrylamide, N-tert-butyl (meth) acrylamide, and N, N-dimethyl (meth) acrylamide. N, N-ethyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N-phenyl (meth) acrylamide, dimethylaminopropyl (meth) acrylamide, N-vinyl Caprolactam, monomethylaminoethyl (meth) acrylate, monoethylaminoethyl (meth) acrylate, monomethylaminopropyl (meth) acrylate, monoethylaminopropyl (meth) acrylate, dimethylamino (meth) acrylate It is also possible to use the chill and the like.
The above nitrogen atom containing monomers may be used individually by 1 type, and may be used in combination of 2 or more type.

  The (meth) acrylic acid ester polymer (A) preferably contains 2 to 20% by mass of a nitrogen atom-containing monomer as a monomer unit constituting the polymer, and particularly 4 to 10% by mass. Is preferable, and further 6 to 9% by mass is preferably contained. When the content of the nitrogen atom-containing monomer is 2% by mass or more, the obtained pressure-sensitive adhesive sufficiently exhibits excellent adhesion to the transparent conductive film and glass and plastic (particularly excellent adhesion to glass and plastic). can do. Further, when the content of the nitrogen atom-containing monomer is 20% by mass or less, the content of other monomer components can be ensured, and the polymer (A) can be suppressed from becoming too hard, The resulting pressure-sensitive adhesive can sufficiently exhibit excellent adhesive strength.

  The (meth) acrylic acid ester polymer (A) preferably contains a total of 5 to 40% by mass of the alicyclic structure-containing monomer and the nitrogen atom-containing monomer as monomer units constituting the polymer. It is preferable to contain -28 mass%, and it is further preferable to contain 15-24 mass%. When the total content of both monomers is 5% by mass or more, the obtained pressure-sensitive adhesive can sufficiently exhibit excellent adhesion to the transparent conductive film, glass and plastic. Moreover, it can suppress that a polymer (A) becomes hard too much that the total content of both monomers is 40 mass% or less, and can fully exhibit the outstanding adhesive force.

  The (meth) acrylic acid ester polymer (A) has, as a monomer unit constituting the polymer, an alkyl group having 1 to 20 carbon atoms in addition to the alicyclic structure-containing monomer and the nitrogen atom-containing monomer ( It is preferable to contain a (meth) acrylic-acid alkylester, and it is preferable to contain especially as a main component (most component in the monomer which comprises a polymer).

  The (meth) acrylic acid ester polymer (A) contains a (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group as a monomer unit constituting the polymer. Can be expressed. Examples of the (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and (meth) acrylic acid n-. Butyl, n-pentyl (meth) acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, n-decyl (meth) acrylate, (meth) acrylic acid Examples include n-dodecyl, myristyl (meth) acrylate, palmityl (meth) acrylate, stearyl (meth) acrylate, and the like. Among these, from the viewpoint of further improving the adhesiveness, (meth) acrylic acid esters having 1 to 8 carbon atoms in the alkyl group are preferred, and n-butyl (meth) acrylate and 2-ethylhexyl (meth) acrylate are particularly preferred. . In addition, these may be used independently and may be used in combination of 2 or more type.

  The (meth) acrylic acid ester polymer (A) may contain 50 to 90% by mass of a (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms as the monomer unit constituting the polymer. The content is preferably 55 to 80% by mass, more preferably 60 to 70% by mass.

  When the adhesive composition P contains the crosslinking agent (B), the (meth) acrylic acid ester polymer (A) is a functional group capable of reacting with the crosslinking agent (B) as a monomer unit constituting the polymer. It is preferable to contain a reactive functional group-containing monomer having a group.

  Examples of the reactive functional group-containing monomer include a monomer having a hydroxyl group in the molecule (hydroxyl group-containing monomer), a monomer having a carboxyl group in the molecule (carboxyl group-containing monomer), and the like. However, it is preferable that the (meth) acrylic acid ester polymer (A) does not contain a carboxyl group-containing monomer as a monomer unit constituting the polymer. Thereby, it can suppress that the obtained adhesive corrodes the transparent conductive film which is a to-be-adhered body, or changes the resistance value of a transparent conductive film.

  Here, “does not contain a carboxyl group-containing monomer” means that it contains substantially no carboxyl group-containing monomer, and does not contain any carboxyl group-containing monomer, and corrosion of the transparent conductive film due to carboxyl groups occurs. It is allowed to contain a carboxyl group-containing monomer to a certain extent. Specifically, the (meth) acrylic acid ester polymer (A) contains a carboxyl group-containing monomer as a monomer unit in an amount of 0.1% by mass or less, preferably 0.01% by mass or less. It is acceptable.

  For the above reasons, the (meth) acrylic acid ester polymer (A) preferably contains a hydroxyl group-containing monomer as the reactive functional group-containing monomer constituting the polymer.

  Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, (meth And (meth) acrylic acid hydroxyalkyl esters such as 3-hydroxybutyl acrylate and 4-hydroxybutyl (meth) acrylate. Among them, 2-hydroxyethyl (meth) acrylate is preferable from the viewpoint of the reactivity of the hydroxyl group in the obtained (meth) acrylic acid ester polymer (A) with the crosslinking agent (B) and the copolymerizability with other monomers. . These may be used alone or in combination of two or more.

  The (meth) acrylic acid ester polymer (A) preferably contains 5 to 30% by mass of a reactive functional group-containing monomer, particularly 10 to 25% by mass, as the monomer unit constituting the polymer. It is preferable to contain 15-20 mass%.

  The (meth) acrylic acid ester polymer (A) may contain a monomer other than the above as a monomer unit constituting the polymer. Examples of the other monomers include (meth) acrylic acid alkoxyalkyl esters such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate, vinyl acetate, and styrene. These may be used alone or in combination of two or more.

  The polymerization mode of the (meth) acrylic acid ester polymer (A) may be a random copolymer or a block copolymer.

  The weight average molecular weight of the (meth) acrylic acid ester polymer (A) is preferably 300,000 to 1,200,000, particularly preferably 400,000 to 1,000,000, and more preferably 600,000 to 700,000. Is preferred. In addition, the weight average molecular weight in this specification is the value of standard polystyrene conversion measured by the gel permeation chromatography (GPC) method.

  In the adhesive composition P, the (meth) acrylic acid ester polymer (A) may be used singly or in combination of two or more. Moreover, the adhesive composition P may further contain a (meth) acrylic acid ester polymer that does not contain an alicyclic structure-containing monomer and / or a nitrogen atom-containing monomer as a constituent monomer unit.

(2) Crosslinking agent (B)
When the pressure-sensitive adhesive composition P containing the cross-linking agent (B) is cross-linked, the cross-linking agent (B) is a reactive functional group-derived reactive functional group constituting the (meth) acrylic acid ester copolymer (A). Reacts with groups. Thereby, the structure by which (meth) acrylic acid ester copolymer (A) was bridge | crosslinked with the crosslinking agent (B) is formed, and the cohesion force of the adhesive which is obtained improves.

  The crosslinking agent (B) may be any one that reacts with the reactive functional group of the (meth) acrylic acid ester polymer (A). For example, an isocyanate crosslinking agent, an epoxy crosslinking agent, and an amine crosslinking agent. , Melamine crosslinking agent, aziridine crosslinking agent, hydrazine crosslinking agent, aldehyde crosslinking agent, oxazoline crosslinking agent, metal alkoxide crosslinking agent, metal chelate crosslinking agent, metal salt crosslinking agent, ammonium salt crosslinking agent, etc. Is mentioned. When the reactive functional group which the (meth) acrylic acid ester polymer (A) has is a hydroxyl group, among them, it is preferable to use an isocyanate-based crosslinking agent excellent in reactivity with the hydroxyl group. In addition, a crosslinking agent (B) can be used individually by 1 type or in combination of 2 or more types.

  The isocyanate-based crosslinking agent contains at least a polyisocyanate compound. Examples of the polyisocyanate compound include aromatic polyisocyanates such as tolylene diisocyanate, diphenylmethane diisocyanate and xylylene diisocyanate, aliphatic polyisocyanates such as hexamethylene diisocyanate, alicyclic polyisocyanates such as isophorone diisocyanate and hydrogenated diphenylmethane diisocyanate, and the like. , And their biuret bodies, isocyanurate bodies, and adduct bodies that are a reaction product with low molecular active hydrogen-containing compounds such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, and castor oil. Among these, trimethylolpropane-modified aromatic polyisocyanate, particularly trimethylolpropane-modified tolylene diisocyanate is preferable from the viewpoint of reactivity with hydroxyl groups.

  The content of the crosslinking agent (B) in the adhesive composition P is preferably 0.05 to 1.00 parts by mass with respect to 100 parts by mass of the (meth) acrylic acid ester polymer (A), In particular, the amount is preferably 0.10 to 0.50 parts by mass, and more preferably 0.15 to 0.30 parts by mass.

(3) Various additives For the adhesive composition P, if desired, various additives usually used in acrylic adhesives, for example, silane coupling agents, antistatic agents, tackifiers, antioxidants, Ultraviolet absorbers, light stabilizers, softeners, fillers, refractive index adjusters, and the like can be added.

(4) Manufacture of adhesive composition The adhesive composition P manufactured the (meth) acrylic acid ester polymer (A), and cross-linked the obtained (meth) acrylic acid ester polymer (A) as desired. It can manufacture by adding an agent (B) and / or an additive.

  The (meth) acrylic acid ester polymer (A) can be produced by polymerizing a mixture of monomer units constituting the polymer by an ordinary radical polymerization method. The polymerization of the (meth) acrylic acid ester polymer (A) can be performed by a solution polymerization method or the like using a polymerization initiator as desired. Examples of the polymerization solvent include ethyl acetate, n-butyl acetate, isobutyl acetate, toluene, acetone, hexane, methyl ethyl ketone, and the like. Two or more kinds may be used in combination.

  Examples of the polymerization initiator include azo compounds and organic peroxides, and two or more kinds may be used in combination. Examples of the azo compound include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-methylbutyronitrile), 1,1′-azobis (cyclohexane 1-carbonitrile), 2 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (2,4-dimethyl-4-methoxyvaleronitrile), dimethyl 2,2′-azobis (2-methylpropionate) 4,4′-azobis (4-cyanovaleric acid), 2,2′-azobis (2-hydroxymethylpropionitrile), 2,2′-azobis [2- (2-imidazolin-2-yl) Propane] and the like.

  Examples of organic peroxides include benzoyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, and di (2-ethoxyethyl) peroxy. Examples include dicarbonate, t-butyl peroxyneodecanoate, t-butyl peroxybivalate, (3,5,5-trimethylhexanoyl) peroxide, dipropionyl peroxide, diacetyl peroxide and the like.

  In addition, in the said superposition | polymerization process, the weight average molecular weight of the polymer obtained can be adjusted by mix | blending chain transfer agents, such as 2-mercaptoethanol.

  When the (meth) acrylic acid ester polymer (A) is obtained, the crosslinking agent (B) and / or additive is added to the solution of the (meth) acrylic acid ester polymer (A) as required, and mixed thoroughly. By doing, the adhesive composition P (coating solution) diluted with the solvent is obtained.

  Examples of the dilution solvent for diluting the adhesive composition P to form a coating solution include aliphatic hydrocarbons such as hexane, heptane, and cyclohexane, aromatic hydrocarbons such as toluene and xylene, methylene chloride, ethylene chloride, and the like. Halogenated hydrocarbons, methanol, ethanol, propanol, butanol, alcohols such as 1-methoxy-2-propanol, acetone, methyl ethyl ketone, ketones such as 2-pentanone, isophorone, cyclohexanone, esters such as ethyl acetate and butyl acetate, ethyl A cellosolv solvent such as cellosolve is used.

  The concentration / viscosity of the coating solution thus prepared is not particularly limited as long as it can be coated, and can be appropriately selected depending on the situation. For example, it dilutes so that the density | concentration of the adhesive composition P may be 10-40 mass%. In addition, when obtaining a coating solution, addition of a dilution solvent etc. is not a necessary condition, and if a viscosity etc. which can be coated with the adhesive composition P are not necessary, a dilution solvent does not need to be added. In this case, the adhesive composition P becomes a coating solution using the polymerization solvent of the (meth) acrylic acid ester polymer (A) as a dilution solvent.

[Adhesive]
The pressure-sensitive adhesive according to this embodiment is obtained by crosslinking the pressure-sensitive adhesive composition P. The pressure-sensitive adhesive composition P can be crosslinked by heat treatment. In addition, this heat processing can also serve as the drying process at the time of volatilizing the dilution solvent of the adhesive composition P, etc.

  When performing heat processing, it is preferable that heating temperature is 50-150 degreeC, and it is especially preferable that it is 70-120 degreeC. The heating time is preferably 30 seconds to 10 minutes, particularly preferably 50 seconds to 2 minutes. After the heat treatment, if necessary, a curing period of about 1 to 2 weeks may be provided at room temperature (for example, 23 ° C., 50% RH). When the curing period is necessary, after the curing period has elapsed, when the curing period is unnecessary, the pressure-sensitive adhesive layer is formed after the heat treatment.

  The pressure-sensitive adhesive obtained by cross-linking the pressure-sensitive adhesive composition P has a transparent conductive film due to the action of the alicyclic structure and nitrogen atoms (particularly nitrogen-containing heterocycle) of the (meth) acrylic acid ester polymer (A). In particular, it exhibits a strong adhesive force to a transparent conductive film made of tin-doped indium oxide (ITO), glass, and plastic, particularly plastic such as polycarbonate and polymethyl methacrylate.

  The pressure-sensitive adhesive layer according to this embodiment preferably has a haze value (measured according to JIS K7136: 2000) of 10% or less, particularly preferably 3% or less, and more preferably 1.5. % Or less is preferable. When the haze value is 1.5% or less, the transparency is very high and it is suitable for optical applications.

  Further, the pressure-sensitive adhesive layer according to this embodiment preferably has a total light transmittance (value measured according to JIS K7105: 1981) of 90% or more, particularly preferably 95% or more. Is preferably 98% or more. When the total light transmittance is 98% or more, the transparency is very high and it is suitable for optical use.

[Adhesive sheet]
As shown in FIG. 1, the pressure-sensitive adhesive sheet 1 according to this embodiment includes two release sheets 12a and 12b and the two release sheets 12a so as to be in contact with the release surfaces of the two release sheets 12a and 12b. , 12b and an adhesive layer 11 sandwiched between the two layers. However, the release sheets 12a and 12b in the pressure-sensitive adhesive sheet 1 are not essential components, and are peeled and removed when the pressure-sensitive adhesive sheet 1 is used. In addition, the release surface of the release sheet in this specification refers to a surface having peelability in the release sheet, and includes both a surface that has been subjected to a release treatment and a surface that exhibits peelability without being subjected to a release treatment. .

(1) Adhesive layer The adhesive layer 11 is comprised from the adhesive formed by bridge | crosslinking the adhesive composition P mentioned above. The thickness of the pressure-sensitive adhesive layer 11 (value measured according to JIS K7130) is preferably 10 to 300 μm, particularly preferably 25 to 250 μm, and more preferably 50 to 100 μm. When the thickness of the pressure-sensitive adhesive layer 11 is 10 μm or more, excellent adhesive force is sufficiently exhibited, and when the thickness of the pressure-sensitive adhesive layer 11 is 300 μm or less, workability is improved. Moreover, when the thickness of the pressure-sensitive adhesive layer 11 is 25 to 100 μm, it is suitable for optical applications, particularly for touch panel applications. The pressure-sensitive adhesive layer 11 may be formed as a single layer or may be formed by laminating a plurality of layers.

(2) Release sheet Examples of the release sheets 12a and 12b include polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polyethylene naphthalate. Phthalate film, polybutylene terephthalate film, polyurethane film, ethylene vinyl acetate film, ionomer resin film, ethylene / (meth) acrylic acid copolymer film, ethylene / (meth) acrylic acid ester copolymer film, polystyrene film, polycarbonate film A polyimide film, a fluororesin film, or the like is used. These crosslinked films are also used. Furthermore, these laminated films may be sufficient.

  It is preferable that the peeling surface (especially the surface in contact with the pressure-sensitive adhesive layer 11) of the release sheets 12a and 12b is subjected to a peeling treatment. Examples of the release agent used for the release treatment include alkyd, silicone, fluorine, unsaturated polyester, polyolefin, and wax release agents. Of the release sheets 12a and 12b, one release sheet is preferably a heavy release release sheet having a high release force, and the other release sheet is preferably a light release release sheet having a low release force.

  Although there is no restriction | limiting in particular about the thickness of release sheet 12a, 12b, Usually, it is about 20-150 micrometers.

(3) Production of pressure-sensitive adhesive sheet As one production example of the pressure-sensitive adhesive sheet 1, a coating liquid of the above-mentioned pressure-sensitive adhesive composition P is applied to the release surface of one release sheet 12a (or 12b), and heat treatment is performed for adhesion. After cross-linking the composition P and forming a coating layer, the release surface of the other release sheet 12b (or 12a) is overlaid on the coating layer. When a curing period is required, a curing period is set, and when the curing period is unnecessary, the coating layer becomes the pressure-sensitive adhesive layer 11 as it is. Thereby, the said adhesive sheet 1 is obtained. The conditions for the heat treatment and curing are as described above.

  As another production example of the pressure-sensitive adhesive sheet 1, a coating liquid of the above-mentioned pressure-sensitive adhesive composition P is applied to the release surface of one release sheet 12 a, a heat treatment is performed to cross-link the pressure-sensitive adhesive composition P, and a coating layer To obtain a release sheet 12a with a coating layer. Moreover, the coating liquid of the said adhesive composition P is apply | coated to the peeling surface of the other peeling sheet 12b, heat processing is performed, the adhesive composition P is bridge | crosslinked, an application layer is formed, and an application layer is attached. A release sheet 12b is obtained. And the peeling sheet 12a with an application layer and the peeling sheet 12b with an application layer are bonded together so that both application layers may mutually contact. When the curing period is necessary, the curing period is set, and when the curing period is unnecessary, the above-mentioned laminated application layer becomes the pressure-sensitive adhesive layer 11 as it is. Thereby, the said adhesive sheet 1 is obtained. According to this production example, even when the pressure-sensitive adhesive layer 11 is thick, it can be stably produced.

  For example, a bar coating method, a knife coating method, a roll coating method, a blade coating method, a die coating method, a gravure coating method, or the like can be used as a method for applying the coating solution of the adhesive composition P.

(4) Adhesive strength Soda of the laminate when the adhesive layer 11 side surface of the laminate obtained by laminating the adhesive layer 11 on a substrate made of a polyethylene terephthalate film having a thickness of 100 μm is attached to soda lime glass. The adhesive strength to lime glass is preferably 20 N / 25 mm or more, particularly preferably 25 to 40 N / 25 mm, and more preferably 30 to 35 N / 25 mm.

  Also, the adhesive layer 11 side of the laminate obtained by laminating the adhesive layer 11 on a base material made of a polyethylene terephthalate film having a thickness of 100 μm is used as an ITO film (a transparent conductive film made of tin-doped indium oxide (ITO) on one side). The polyethylene terephthalate film provided with a thickness of 125 μm is attached to an ITO film, and the adhesive strength of the laminate to the ITO film is preferably 10 N / 25 mm or more, particularly 15 to 30 N / 25 mm. More preferably, it is preferably 20 to 25 N / 25 mm.

  In addition, although the adhesive force here means the adhesive force measured by the 180 degree peeling method according to JIS Z0237: 2009, the measurement sample has a width of 25 mm and a length of 100 mm, and the measurement sample is attached. After being applied to the body by applying pressure at 0.5 MPa and 50 ° C. for 20 minutes, the sample was left for 24 hours under conditions of normal pressure, 23 ° C. and 50% RH, and then measured at a peeling rate of 300 mm / min. To do.

  When the pressure-sensitive adhesive layer 11 is composed of a pressure-sensitive adhesive obtained by cross-linking the pressure-sensitive adhesive composition P, it can exhibit a high pressure-sensitive adhesive force for both glass and a transparent conductive film as described above. it can. When the adhesive force with respect to both exists in the said range, the cover glass and ITO film (film sensor) in a touch panel, for example are reliably adhere | attached.

(5) Use of pressure-sensitive adhesive sheet By using the pressure-sensitive adhesive sheet 1, for example, the capacitive touch panel 2 shown in FIG. 2 can be manufactured. The touch panel 2 includes a display module 3, a first film sensor 5 a laminated thereon via an adhesive layer 4 a, and a second film sensor 5 b laminated thereon via an adhesive layer 4 b. And the cover material 6 laminated | stacked through the adhesive layer 11 on it is comprised.

  The pressure-sensitive adhesive layer 11 in the touch panel 2 is the pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet 1.

  Examples of the display module 3 include a liquid crystal (LCD) module, a light emitting diode (LED) module, an organic electroluminescence (organic EL) module, and electronic paper.

  The pressure-sensitive adhesive layers 4a and 4b may be formed by the pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet 1, or may be formed by other pressure-sensitive adhesives or pressure-sensitive adhesive sheets. In the latter case, the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer 4 includes an acrylic pressure-sensitive adhesive, a rubber-based pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive, a urethane-based pressure-sensitive adhesive, a polyester-based pressure-sensitive adhesive, and a polyvinyl ether-based pressure-sensitive adhesive. However, among them, an acrylic pressure-sensitive adhesive is preferable.

  The 1st film sensor 5a and the 2nd film sensor 5b are normally comprised from the base film 51 and the patterned transparent conductive film 52, respectively. Although it does not specifically limit as the base film 51, For example, a polyethylene terephthalate film, an acrylic film, a polycarbonate film etc. are used.

  Examples of the transparent conductive film 52 include metals such as platinum, gold, silver and copper, oxides such as tin oxide, indium oxide, cadmium oxide, zinc oxide and zinc dioxide, tin-doped indium oxide (ITO), and zinc oxide-doped oxide. Examples include composite oxides such as indium, fluorine-doped indium oxide, antimony-doped tin oxide, fluorine-doped tin oxide, and aluminum-doped zinc oxide, and non-oxidized compounds such as chalcogenide, lanthanum hexaboride, titanium nitride, and titanium carbide. Among these, those made of tin-doped indium oxide (ITO) are preferable.

  One of the transparent conductive film 52 of the first film sensor 5a and the transparent conductive film 52 of the second film sensor 5b normally constitutes a circuit pattern in the X-axis direction, and the other constitutes a circuit pattern in the Y-axis direction. .

  The transparent conductive film 52 of the second film sensor 5b in the present embodiment is located above the second film sensor 5b in FIG. On the other hand, the transparent conductive film 52 of the first film sensor 5a is positioned on the upper side of the first film sensor 5a in FIG. It may be located on the lower side.

  The cover material 6 is mainly composed of a glass plate or a plastic plate. The glass plate is not particularly limited. For example, chemically tempered glass, alkali-free glass, quartz glass, soda lime glass, barium / strontium-containing glass, aluminosilicate glass, lead glass, borosilicate glass, barium borosilicate glass. Etc. The plastic plate is not particularly limited, and examples thereof include an acrylic plate made of polymethyl methacrylate and the like, and a polycarbonate plate.

  In addition, a functional layer such as a hard coat layer, an antireflection layer, or an antiglare layer may be provided on one side or both sides of the glass plate or plastic plate, or a hard coat film, an antireflection film, or an antiglare film. Such optical members may be laminated.

  In the present embodiment, the cover material 6 has a step on the surface on the pressure-sensitive adhesive layer 11 side, and specifically has a step due to the presence or absence of the printing layer 3. The print layer 3 is generally formed in a frame shape on the pressure-sensitive adhesive layer 11 side of the cover material 6.

  The material which comprises the printing layer 3 is not specifically limited, The well-known material for printing is used. The thickness of the printing layer 3, that is, the height of the step, is preferably 3 to 45 μm, more preferably 5 to 35 μm, particularly preferably 7 to 25 μm, and preferably 7 to 15 μm. Further preferred.

  Further, the thickness of the printing layer 3 (the height of the step) is preferably 3 to 30% of the thickness of the pressure-sensitive adhesive layer 11, particularly preferably 3.2 to 20%, and more preferably 3 It is preferable that it is 5 to 15%. As a result, the pressure-sensitive adhesive layer 11 can easily follow the step formed by the printing layer 3, and the occurrence of floating or bubbles in the vicinity of the step is suppressed.

An example of the manufacturing method of the touch panel 2 will be described below.
One release sheet 12a is peeled from the pressure-sensitive adhesive sheet 1, and the exposed pressure-sensitive adhesive layer 11 is bonded to the second film sensor 5b so as to be in contact with the patterned transparent conductive film 52 of the second film sensor 5b. To do. On the other hand, the pressure-sensitive adhesive layer 4b provided on the release sheet is bonded to the first film sensor 5a so as to be in contact with the patterned transparent conductive film 52 of the first film sensor 5a.

  Then, the release film remaining on the pressure-sensitive adhesive layer 4b is peeled off, and the exposed pressure-sensitive adhesive layer 4b is opposite to the surface on which the pressure-sensitive adhesive layer 11 is laminated in the second film sensor 5b (second surface). Both are bonded so that it may touch the exposed surface of the base film 51 of the film sensor 5b. Thereby, the laminated body by which the peeling sheet 12b, the adhesive layer 11, the 2nd film sensor 5b, the adhesive layer 4b, and the 1st film sensor 5a are laminated | stacked one by one is obtained.

  Next, the pressure-sensitive adhesive layer 4a provided on the release sheet is bonded to the surface of the laminate on the first film sensor 5a side (exposed surface of the base film 51 of the first film sensor 5a). Subsequently, the other release sheet 12b is peeled from the laminate, and the cover material 6 is pasted so that the printed layer 7 side of the cover material 6 contacts the pressure-sensitive adhesive layer 11 with respect to the exposed pressure-sensitive adhesive layer 11. Match. Thereby, the structure by which the cover material 6, the adhesive layer 11, the 2nd film sensor 5b, the adhesive layer 4b, the 1st film sensor 5a, the adhesive layer 4a, and a peeling sheet are laminated | stacked one by one is obtained.

  Finally, the release sheet is peeled off from the structure, and the structure is bonded to the display module 3 so that the exposed pressure-sensitive adhesive layer 4 a is in contact with the display module 3. Thereby, the touch panel 2 shown in FIG. 2 is manufactured.

  In the touch panel 2 described above, the transparent conductive film 52 of the second film sensor 5 b and the cover material 6 are bonded by the adhesive layer 11. As described above, since the pressure-sensitive adhesive layer 11 exhibits a strong adhesive force to the transparent conductive film, glass, and plastic, the second film sensor 5b and the cover material 6 are securely bonded.

  The embodiment described above is described for facilitating understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

  For example, one of the release sheets 12a and 12b in the pressure-sensitive adhesive sheet 1 may be omitted.

  EXAMPLES Hereinafter, although an Example etc. demonstrate this invention further more concretely, the scope of the present invention is not limited to these Examples etc.

[Example 1]
1. Preparation of (meth) acrylic acid ester copolymer 60 parts by mass of 2-ethylhexyl acrylate, 10 parts by mass of N-acryloylmorpholine, 10 parts by mass of isobornyl acrylate and 20 parts by mass of 2-hydroxyethyl acrylate, A (meth) acrylic acid ester copolymer (A) was prepared. When the molecular weight of this (meth) acrylic acid ester copolymer (A) was measured by the method mentioned later, it was weight average molecular weight (Mw) 600,000.

2. Preparation of adhesive composition (Meth) acrylate copolymer (A) 100 parts by mass (in terms of solid content; the same applies hereinafter) obtained in the above step (1), and trimethylol as a crosslinking agent (B) 0.25 parts by mass of propane-modified tolylene diisocyanate (product name “BHS8515” manufactured by Toyochem Co., Ltd.), sufficiently stirred, and diluted with methyl ethyl ketone to give an adhesive composition having a solid content concentration of 35% by mass A coating solution was obtained.

Here, Table 1 shows the composition of the adhesive composition. Details of the abbreviations and the like described in Table 1 are as follows.
[(Meth) acrylic ester copolymer (A)]
2EHA: 2-ethylhexyl acrylate BA: n-butyl acrylate ACMO: N-acryloylmorpholine IBXA: isobornyl acrylate HEA: 2-hydroxyethyl acrylate
[Crosslinking agent (B)]
TDI: Trimethylolpropane modified tolylene diisocyanate (Toyochem, product name “BHS8515”)

3. Manufacture of pressure-sensitive adhesive sheet The release-treated surface of a heavy-peelable release sheet (product name “PET752150”, manufactured by Lintec Corporation) obtained by removing one side of a polyethylene terephthalate film with a silicone-based release agent. Then, after coating with a knife coater so that the thickness after drying was 25 μm, the coating layer was formed by heat treatment at 90 ° C. for 1 minute.

  Similarly, a release treatment of a light release release sheet (product name “SP-PET382120” manufactured by Lintec Corporation) in which one side of a polyethylene terephthalate film was release-treated with a silicone-based release agent was applied to the obtained adhesive composition coating solution. The surface was coated with a knife coater so that the thickness after drying was 25 μm, and then heat-treated at 90 ° C. for 1 minute to form a coating layer.

  Subsequently, the heavy release type release sheet with the coating layer obtained above and the light release type release sheet with the coating layer obtained above were bonded so that both coating layers were in contact with each other. By curing for 7 days under the condition of 50% RH, a pressure-sensitive adhesive sheet having a structure of heavy release type release sheet / pressure-sensitive adhesive layer (thickness: 50 μm) / light release type release sheet was produced. The thickness of the pressure-sensitive adhesive layer is a value measured using a constant pressure thickness measuring instrument (manufactured by Teclock, product name “PG-02”) in accordance with JIS K7130.

[Examples 2-3, Comparative Examples 1-2]
A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that the type and ratio of each monomer constituting the (meth) acrylic acid ester copolymer (A) were changed as shown in Table 1.

Here, the above-mentioned weight average molecular weight (Mw) is a polystyrene-reduced weight average molecular weight measured under the following conditions (GPC measurement) using gel permeation chromatography (GPC).
<Measurement conditions>
GPC measurement device: manufactured by Tosoh Corporation, HLC-8020
GPC column (passed in the following order): TSK guard column HXL-H manufactured by Tosoh Corporation
TSK gel GMHXL (× 2)
TSK gel G2000HXL
・ Measurement solvent: Tetrahydrofuran ・ Measurement temperature: 40 ° C.

[Test Example 1] (Measurement of adhesive strength)
The light release type release sheet was peeled off from the pressure sensitive adhesive sheets obtained in Examples and Comparative Examples, and the exposed pressure sensitive adhesive layer was easily made of a polyethylene terephthalate film (PET A4300, manufactured by Toyobo Co., Ltd., thickness: 100 μm) having an easy adhesion layer. Bonded to the adhesive layer. The laminate was cut into a width of 25 mm and a length of 100 mm, and this was used as a sample. The peelable release sheet was peeled from the sample, and the exposed adhesive layer was a polyethylene terephthalate film (made by Oike Kogyo Co., Ltd., ITO film, thickness provided with a transparent conductive film made of tin-doped indium oxide (ITO) on one side. : 125 μm).

  Then, after leaving for 24 hours under conditions of normal pressure, 23 ° C., and 50% RH, using a tensile tester (Orientec, Tensilon), according to JIS Z0237: 2009, a peeling rate of 300 mm / min, The adhesive strength (N / 25 mm) was measured under the condition of a peeling angle of 180 °. The results are shown in Table 1.

  Further, the heavy release type release sheet is peeled off from the sample, and the exposed pressure-sensitive adhesive layer is attached to soda lime glass (Central Glass Co., Ltd., thickness: 1.1 mm), and adhesive strength (N / 25 mm). The results are shown in Table 1.

[Test Example 2] (Measurement of optical performance)
About the adhesive layer of the adhesive sheet obtained by the Example and the comparative example, using a haze meter (Nippon Denshoku Industries Co., Ltd., NDH5000), haze value (%) according to JISK7136: 2000, JISK7105: The total light transmittance (%) was measured according to 1981. The results are shown in Table 1.

  As can be seen from Table 1, the pressure-sensitive adhesive sheets obtained in the examples are very large in both the adhesive strength to the transparent conductive film and the adhesive strength to glass, and have excellent adhesive strength to both the transparent conductive film and glass. Demonstrated. Moreover, the adhesive sheet obtained in the Example had transparency suitable for optical applications.

  The pressure-sensitive adhesive composition, pressure-sensitive adhesive and pressure-sensitive adhesive sheet of the present invention are very useful for bonding a cover material and a transparent conductive film in a capacitive touch panel, for example.

DESCRIPTION OF SYMBOLS 1 ... Adhesive sheet 11 ... Adhesive layer 12a, 12b ... Release sheet 2 ... Touch panel 3 ... Display body module 4a, 4b ... Adhesive layer 5a ... 1st film sensor 5b ... 2nd film sensor 51 ... Base film 52 ... Transparent conductive film 6 ... Cover material 7 ... Print layer

Claims (7)

(Meth) A pressure-sensitive adhesive composition comprising an acrylic acid ester polymer, a crosslinking agent,
The (meth) acrylic acid ester polymer contains 50 to 90% by mass of a (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms as the monomer unit constituting the polymer , and is alicyclic. a monomer having a monomer and a nitrogen atom having a structure containing a total of 5 to 40 mass%, the contained 5 to 30 mass% of a monomer having a functional group reactive with the crosslinking agent, two or more olefinic double in the molecule Does not contain a monomer having a bond ,
The pressure-sensitive adhesive composition, wherein the monomer having a nitrogen atom has a nitrogen-containing heterocyclic ring .   The (meth) acrylic acid ester polymer contains 3 to 20% by mass of the monomer having the alicyclic structure as a monomer unit constituting the polymer, and 2 to 20% by mass of the monomer having the nitrogen atom. It contains, The adhesive composition of Claim 1 characterized by the above-mentioned. It said alicyclic structure, adhesive composition according to claim 1 or 2, characterized in that it comprises an isobornyl skeleton. The said (meth) acrylic acid ester polymer does not contain the monomer which has a carboxyl group as a monomer unit which comprises the said polymer, The adhesive composition as described in any one of Claims 1-3 characterized by the above-mentioned. object. The adhesive which hardens | cures the adhesive composition as described in any one of Claims 1-4 . Two release sheets,
An adhesive layer sandwiched between the release sheets so as to be in contact with the release surfaces of the two release sheets;
The said adhesive layer consists of an adhesive of Claim 5 , The adhesive sheet characterized by the above-mentioned. The pressure-sensitive adhesive sheet according to claim 6 , wherein the pressure-sensitive adhesive sheet is used for bonding a transparent conductive film and glass or plastic.

Images