JP6071224B2 - Adhesive sheet - Google Patents

Description

  The present invention relates to a pressure-sensitive adhesive composition, a pressure-sensitive adhesive (a material obtained by curing a pressure-sensitive adhesive composition), and a pressure-sensitive adhesive sheet, and in particular, a pressure-sensitive adhesive composition suitable for optical members such as polarizing plates, a pressure-sensitive adhesive, and The present invention relates to an adhesive sheet.

  In recent years, a liquid crystal display device (LCD) is widely used as a display device, but a liquid crystal cell is used as an optical component constituting the liquid crystal display device. In general, the liquid crystal cell is arranged such that the alignment layers of the two transparent electrode substrates on which the alignment layers are formed are placed inside, with a predetermined interval by a spacer, and the periphery thereof is sealed to form the two transparent electrode substrates. A liquid crystal material is sandwiched between them. Usually, a polarizing plate is bonded to the outside of two transparent electrode substrates in a liquid crystal cell via an adhesive.

  The polarizing plate is generally composed of a polarizing film having a three-layer structure in which an optically isotropic film such as a triacetyl cellulose (TAC) film is bonded to both surfaces of a polyvinyl alcohol-based polarizer. Is provided with an adhesive layer for the purpose of adhering to the transparent electrode substrate and the like, and is usually used as a polarizing plate with an adhesive.

  In order to improve durability, the pressure-sensitive adhesive composition for forming the pressure-sensitive adhesive layer is generally added with a crosslinking agent and subjected to a crosslinking treatment to form a pressure-sensitive adhesive layer. However, thermal crosslinking agents such as isocyanate-based crosslinking agents and epoxy-based crosslinking agents do not complete crosslinking after coating and drying, and usually require aging for about 3 days to 1 week for complete crosslinking. is there.

  Before the pressure-sensitive adhesive-attached polarizing plate is attached to the liquid crystal cell, various processing processes such as punching and slitting are performed. Here, when performing such processing, if the above aging is not sufficiently performed, the adhesive adheres to the cutting blade, or the adhesive protrudes from the cut surface of the cut member, and the members are overlapped. This causes a problem that the upper and lower members adhere to each other. On the other hand, when a heating process is performed to promote aging, dimensional changes of the polarizing plate and the retardation plate occur, and optical distortion is likely to occur.

  Since the aging treatment has a long time as described above, the productivity is remarkably inhibited. That is, it is very advantageous in terms of productivity that the processing as described above can be performed quickly without the aging treatment after the optical member with an adhesive is manufactured.

  In order to eliminate the need for an aging period, a pressure-sensitive adhesive that does not contain a thermal crosslinking agent and that cures the pressure-sensitive adhesive composition with ultraviolet rays using a pressure-sensitive adhesive composition containing an acrylic polymer and an ultraviolet curable resin Has been proposed (Patent Documents 1 and 2). The pressure-sensitive adhesives described in these documents are those that adhere the polarizing plate and the glass substrate with good durability, have excellent light leakage prevention properties, and have reworkability with respect to the glass substrate.

Japanese Patent No. 3921017 JP 2011-190302 A

  Conventionally, after polarizing the surface of a polarizing plate, it is common to laminate an adhesive layer on the surface. However, with the recent drastic price reduction of liquid crystal display devices, it has been strongly desired to omit the saponification treatment step on the polarizing plate surface.

  In a polarizing plate in which the saponification treatment step is omitted, durability is often a problem because the adhesion between the polarizing plate and the pressure-sensitive adhesive layer is extremely reduced. This problem is particularly noticeable in pressure-sensitive adhesives that do not require the aging period described in the above document.

  The present invention has been made in view of such a situation, does not require aging after the formation of the pressure-sensitive adhesive layer, and has excellent adhesion to a substrate, particularly a polarizing plate not subjected to saponification treatment. It aims at providing an adhesive composition, an adhesive, and an adhesive sheet.

  In order to achieve the above object, first, the present invention provides a (meth) acrylic acid ester having a weight average molecular weight of 600,000 to 2,000,000 and containing a monomer having a nitrogen atom as a monomer unit constituting the polymer. Provided is a pressure-sensitive adhesive composition comprising a polymer (A) and an active energy ray-curable component (B) (Invention 1).

  The pressure-sensitive adhesive composition according to the invention (invention 1) does not require aging because the curing of the pressure-sensitive adhesive is substantially completed immediately after formation of the pressure-sensitive adhesive layer by irradiation with active energy rays, and the pressure-sensitive adhesive layer Various physical properties of the pressure-sensitive adhesive are stabilized immediately after formation. The pressure-sensitive adhesive obtained by curing the pressure-sensitive adhesive composition according to the invention (Invention 1) contains a monomer having a nitrogen atom as a constituent monomer unit in the (meth) acrylic acid ester polymer (A). In particular, the adhesion to a polarizing plate not subjected to saponification treatment is greatly improved, and excellent durability is exhibited.

  In the said invention (invention 1), it is preferable that the monomer which has the said nitrogen atom is a monomer which has a tertiary amino group (invention 2).

  In the above invention (Invention 2), the monomer having a tertiary amino group is preferably at least one selected from N, N-dimethylaminoethyl acrylate and N, N-dimethylaminoethyl methacrylate ( Invention 3).

  In the said invention (invention 1-3), the said (meth) acrylic acid ester polymer (A) is 0.01-5.0 mass% of monomers which have the said nitrogen atom as a monomer unit which comprises the said polymer. It is preferable to contain (Invention 4).

  In the said invention (invention 1-4), it is preferable that the ratio of the said active energy ray hardening component (B) with respect to 100 mass parts of said (meth) acrylic acid ester polymers (A) is 1-25 mass parts. (Invention 5).

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

  In the said invention (invention 6), it is preferable that content of the said photoinitiator (C) is 2-15 mass parts with respect to 100 mass parts of said active energy ray hardening components (B) (invention). 7).

  In the adhesive composition according to the invention (Inventions 1 to 7), the active energy ray-curable component (B) is at least one selected from a polyfunctional (meth) acrylate monomer and a polyfunctional (meth) acrylate oligomer. Or tris ((meth) acryloxyethyl) isocyanurate is preferred.

  Moreover, it is preferable that the adhesive composition which concerns on the said invention (invention 1-7) contains a silane coupling agent (D) further.

  2ndly, this invention provides the adhesive which hardens the said adhesive composition (invention 1-7) by irradiation of an active energy ray (invention 8).

  The pressure-sensitive adhesive according to the invention (Invention 8) preferably has a storage elastic modulus (G ′) at 23 ° C. of 0.01 to 0.8 MPa (Invention 9).

In the pressure-sensitive adhesive according to the above inventions (Inventions 8 and 9), the irradiation amount of the active energy ray is preferably 10 to 2000 mJ / cm ² .

  Thirdly, the present invention provides a pressure-sensitive adhesive sheet comprising a base material and a pressure-sensitive adhesive layer, wherein the pressure-sensitive adhesive layer is composed of the pressure-sensitive adhesive (Inventions 8 and 9). (Invention 10).

  In the said invention (invention 10), it is preferable that the said base material is an optical member (invention 11).

  In the said invention (invention 11), it is preferable that the said optical member is a polarizing plate (invention 12).

  Fourthly, the present invention is an adhesive sheet comprising 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. A pressure-sensitive adhesive sheet, characterized in that the layer is composed of the pressure-sensitive adhesive (Inventions 8 and 9) (Invention 13).

  The pressure-sensitive adhesive composition according to the present invention does not require aging because the curing of the pressure-sensitive adhesive is substantially completed immediately after the formation of the pressure-sensitive adhesive layer by irradiation with active energy rays. Various physical properties of the agent are stabilized. As a result, it is possible to quickly carry out the shipment of the member having the pressure-sensitive adhesive layer made of the pressure-sensitive adhesive and the introduction of the next process, which is very advantageous in terms of the stock burden and productivity of the intermediate material.

  Further, the pressure-sensitive adhesive obtained by curing the pressure-sensitive adhesive composition according to the present invention comprises a (meth) acrylic ester polymer (A) containing a monomer having a nitrogen atom as a constituent monomer unit. Adhesiveness with the polarizing plate which has not been processed is greatly improved, and excellent durability is exhibited.

It is sectional drawing of the adhesive sheet which concerns on the 1st Embodiment of this invention. It is sectional drawing of the adhesive sheet which concerns on the 2nd Embodiment of this invention.

Hereinafter, embodiments of the present invention will be described.
[Adhesive composition]
The pressure-sensitive adhesive composition according to this embodiment (hereinafter referred to as “pressure-sensitive adhesive composition P”) has a weight average molecular weight (Mw) of 600,000 to 2,000,000, and nitrogen atoms are used as monomer units constituting the polymer. (Meth) acrylic acid ester polymer (A) (hereinafter sometimes simply referred to as “polymer (A)”) containing the monomer (nitrogen atom-containing monomer) having, and active energy ray-curable component (B) Preferably, it further contains a photopolymerization initiator (C) or a silane coupling agent (D). 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”.

  The adhesive composition P is easy to handle and excellent in coatability because the curing (crosslinking) reaction does not proceed before irradiation with active energy rays. When the adhesive composition P is irradiated with active energy rays, the plurality of active energy ray-curable components (B) are bonded to each other to form a three-dimensional network structure. A plurality of high molecular weight polymers (A) are inserted into the three-dimensional network structure and restrained, and it is presumed that a pseudo cross-linked structure is formed between the high molecular weight polymers (A) ( These entire structures are hereinafter referred to as “structure X”). Since the curing of the pressure-sensitive adhesive is substantially completed immediately after the irradiation with the active energy ray, aging after the pressure-sensitive adhesive layer is formed is not necessary. Various physical properties are stable. Further, the resulting pressure-sensitive adhesive is such that the (meth) acrylic acid ester polymer (A) contains a nitrogen atom-containing monomer as a constituent monomer unit, so that it is not subjected to a saponification treatment due to its polarity. Adhesion with the polarizing plate is greatly improved, and combined with the above structure X, excellent durability is exhibited.

  The nitrogen atom-containing monomer contained in the (meth) acrylic acid ester polymer (A) as a constituent monomer unit includes a monomer having an amino group, a monomer having an amide group, a monomer having a nitrogen-containing heterocyclic ring such as a pyridinium ring, etc. Is mentioned. Among these, a monomer having an amino group is preferable, and a monomer having a tertiary amino group is particularly preferable. Examples of the monomer having a tertiary amino group include N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, and the like, and among them, N, N-dimethyl acrylate. Aminoethyl and N, N-dimethylaminoethyl methacrylate are preferred. These nitrogen atom-containing monomers have an effect of particularly improving the adhesiveness with a polarizing plate (particularly a polarizing plate not subjected to saponification treatment). These may be used alone or in combination of two or more.

  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 in order to develop adhesiveness. It is preferable. 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 4 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) is not limited to the effects of the present invention other than the nitrogen atom-containing monomer and the (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group. As appropriate, another monomer can be used as a constituent unit.

  The other monomer may be a monomer having a reactive functional group (reactive functional group-containing monomer) or a non-reactive monomer. Preferred 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. More than one species can be used in combination.

  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. These may be used alone or in combination of two or more.

  Examples of the carboxyl group-containing monomer include ethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, and citraconic acid. These may be used alone or in combination of two or more.

  Non-reactive monomers include, for example, (meth) acrylic acid alkoxyalkyl esters such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate, and aliphatic rings such as cyclohexyl (meth) acrylate ( (Meth) acrylic acid ester, (meth) acrylic acid ester having an aromatic ring such as phenyl (meth) acrylate, vinyl acetate, styrene and the like. These may be used alone or in combination of two or more.

  The (meth) acrylic acid ester polymer (A) preferably contains 0.01 to 5.0% by mass of the nitrogen atom-containing monomer as a monomer unit constituting the polymer, particularly 0.05 to 5.0%. The content is preferably 3.5% by mass, and more preferably 0.1 to 2.0% by mass. By containing the nitrogen atom-containing monomer in the above range, the obtained pressure-sensitive adhesive has excellent adhesion to the base material, and the durability is also improved. If the content of the nitrogen atom-containing monomer is less than 0.01% by mass, this effect may not be sufficiently obtained. On the other hand, when the content of the nitrogen atom-containing monomer exceeds 5.0% by mass, the adhesive strength of the resulting pressure-sensitive adhesive, and consequently the durability, may be lowered, or the peelability and reworkability may be inferior.

  The (meth) acrylic acid ester polymer (A) is a combination of a (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group and the non-reactive monomer as a monomer unit constituting the polymer. 50 to 99.99 mass%, preferably 80 to 99.00 mass%, more preferably 93 to 98 mass%. When the total content of the (meth) acrylic acid alkyl ester and the non-reactive monomer is less than 50% by mass, the adhesive strength may be too low. On the other hand, if the content of the (meth) acrylic acid alkyl ester exceeds 99.99% by mass, the blending ratio of the nitrogen atom-containing monomer may be insufficient.

  Moreover, when using together the (meth) acrylic-acid alkylester whose carbon number of an alkyl group is 1-20, and the said non-reactive monomer, the (meth) acrylic-acid alkylester whose carbon number of the alkyl group in both is 1-20 From the viewpoint of improving the adhesive strength, the proportion occupied by is preferably 50% by mass or more, particularly preferably 60% by mass or more, and further preferably 70% by mass or more. In addition, 100 mass% may be sufficient as (meth) acrylic-acid alkylester whose carbon number of an alkyl group is 1-20 as an upper limit of the said mixture ratio of both.

  The (meth) acrylic acid ester polymer (A) preferably contains 0.01 to 10% by mass of the reactive functional group-containing monomer as a monomer unit constituting the polymer, particularly 0.05 to It is preferable to contain 8.0 mass%, and it is further preferable to contain 0.1-5.0 mass%. By containing the reactive functional group-containing monomer in the above range, the structure X can be efficiently formed. Moreover, when the adhesive composition P contains a silane coupling agent (D), the adhesiveness with respect to the glass substrate of the obtained adhesive can be improved by reaction with the said silane coupling agent (D). it can.

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

  The (meth) acrylic acid ester polymer (A) has a weight average molecular weight of 600,000 to 2,000,000, preferably 800,000 to 1,800,000, particularly preferably 1,000,000 to 1,500,000. In addition, the weight average molecular weight in this specification is the value of polystyrene conversion measured by the gel permeation chromatography (GPC) method.

  If the weight average molecular weight of the (meth) acrylic acid ester polymer (A) is less than 600,000, the resulting pressure-sensitive adhesive may be inferior in durability and reworkability. Moreover, when the weight average molecular weight of the (meth) acrylic acid ester polymer (A) exceeds 2 million, the compatibility with the active energy ray-curable component (B) and the like deteriorates, and the formation of the structure X becomes insufficient. , Durability may be reduced.

  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 (A ′) that does not contain a nitrogen atom-containing monomer as a constituent monomer unit. As such a (meth) acrylic acid ester polymer (A ′), for example, a (meth) acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms, a reactive functional group-containing monomer used as desired, and a desired one. And copolymers with other monomers used in accordance with the above.

  Moreover, when using said polymer (A) and polymer (A ') together, the reactive functional group containing monomer which is a structural unit of these polymers, for example, a hydroxyl group containing monomer, a carboxyl group containing monomer, respectively, It is preferable to make the types different. This is because it is possible to distinguish the polymer that acts with the silane coupling agent (D) and the polymer that imparts antistatic properties and the like in design.

  The blending ratio of the (meth) acrylate polymer (A ′) to 100 parts by mass of the (meth) acrylate polymer (A) is preferably 50 parts by mass or less, particularly 30 parts by mass or less. Is preferred.

  The active energy ray-curable component (B) is not particularly limited as long as it is a component that is cured by irradiation with active energy rays without impeding the effects of the present invention, and may be any of a monomer, an oligomer, or a polymer. Or a mixture thereof. The active energy ray-curable component (B) is preferably at least one selected from a polyfunctional (meth) acrylate monomer and a polyfunctional (meth) acrylate oligomer. Among them, a (meth) acrylic acid ester polymer ( A polyfunctional (meth) acrylate monomer excellent in compatibility with A) and the like is preferable.

  Examples of the polyfunctional (meth) acrylate monomer include 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, and polyethylene glycol di (meth). ) Acrylate, neopentyl glycol adipate di (meth) acrylate, hydroxypivalic acid neopentyl glycol di (meth) acrylate, dicyclopentanyl di (meth) acrylate, caprolactone modified dicyclopentenyl di (meth) acrylate, ethylene oxide modified phosphoric acid Di (meth) acrylate, allylated cyclohexyl di (meth) acrylate, isocyanurate di (meth) acrylate, trimethylolpropane tri (meth) acrylate, dipentaerythritol Li (meth) acrylate, propionic acid modified dipentaerythritol tri (meth) acrylate, pentaerythritol tri (meth) acrylate, propylene oxide modified trimethylolpropane tri (meth) acrylate, tris ((meth) acryloxyethyl) isocyanurate, Examples include propionic acid-modified dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and caprolactone-modified dipentaerythritol hexa (meth) acrylate. Among them, tris ((meth) acryloxyethyl) isocyanurate is preferable. In particular, tris (acryloxyethyl) isocyanurate is preferable. These may be used alone or in combination of two or more.

  Examples of polyfunctional (meth) acrylate oligomers include polyester acrylate oligomers, epoxy acrylate oligomers, urethane acrylate oligomers, polyether acrylate oligomers, polybutadiene acrylate oligomers, and silicone acrylate oligomers.

  Polyester acrylate oligomers can be obtained by, for example, esterifying the hydroxyl groups of polyester oligomers having hydroxyl groups at both ends obtained by condensation of polyvalent carboxylic acids and polyhydric alcohols with (meth) acrylic acid, or polyvalent carboxylic acids. It can be obtained by esterifying the terminal hydroxyl group of an oligomer obtained by adding alkylene oxide to (meth) acrylic acid.

  The epoxy acrylate oligomer can be obtained, for example, by reacting (meth) acrylic acid with an oxirane ring of a relatively low molecular weight bisphenol type epoxy resin or novolak type epoxy resin and esterifying it. Further, a carboxyl-modified epoxy acrylate oligomer obtained by partially modifying an epoxy acrylate oligomer with a dibasic carboxylic acid anhydride can also be used.

  The urethane acrylate oligomer can be obtained, for example, by esterifying a polyurethane oligomer obtained by a reaction between polyether polyol or polyester polyol and polyisocyanate with (meth) acrylic acid.

  The polyether acrylate oligomer can be obtained by esterifying the hydroxyl group of the polyether polyol with (meth) acrylic acid.

  The above polyfunctional (meth) acrylate monomers and polyfunctional (meth) acrylate oligomers can be used singly or in combination of two or more. Moreover, a polyfunctional (meth) acrylate monomer and a polyfunctional (meth) acrylate oligomer can be used in combination.

  In the adhesive composition P, the active energy ray-curable component (B) may be used alone or in combination of two or more.

  The mixing ratio of the active energy ray-curable component (B) to 100 parts by mass of the (meth) acrylic acid ester polymer (A) is preferably 1 to 25 parts by mass, particularly 2 to 20 parts by mass. More preferably, it is 5-10 mass parts.

  The pressure-sensitive adhesive obtained from the pressure-sensitive adhesive composition P containing the (meth) acrylic acid ester polymer (A) and the active energy ray-curable component (B) at the above ratio is presumed to form the structure X well. Is done.

  Here, when using an ultraviolet-ray as an active energy ray irradiated with respect to the adhesive composition P, it is preferable that the adhesive composition P contains a photoinitiator (C) further. By containing the photopolymerization initiator (C) in this way, the active energy ray-curable component (B) can be efficiently cured, and the polymerization curing time and the amount of active energy ray irradiation can be reduced. it can.

  Specific examples of the photopolymerization initiator (C) include benzophenone, acetophenone, benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzoin benzoic acid, benzoin methyl benzoate, and benzoin. Dimethyl ketal, 2,4-diethylthioxanthone, 1-hydroxycyclohexyl phenyl ketone, benzyl diphenyl sulfide, tetramethyl thiuram monosulfide, azobisisobutyronitrile, benzyl, dibenzyl, diacetyl, β-chloranthraquinone, (2 , 4,6-trimethylbenzyldiphenyl) phosphine oxide, 2-benzothiazole-N, N-diethyldithiocarbamate and the like. These may be used alone or in combination of two or more.

  It is preferable that a photoinitiator (C) is used in the quantity of the range of 2-15 mass parts with respect to 100 mass parts of active energy ray hardening components (B), especially 5-12 mass parts.

  The adhesive composition P preferably further contains a silane coupling agent (D). When this silane coupling agent (D) is contained, the adhesiveness of the resulting pressure-sensitive adhesive to the glass substrate can be improved, and as a result, the durability is further improved. For example, when the (meth) acrylic acid ester polymer (A) has a reactive functional group-containing monomer as a structural unit, the organic reactive group of the silane coupling agent (D) and the (meth) acrylic acid ester polymer ( On the other hand, the alkoxysilyl group of the silane coupling agent (D) acts on the adherend surface such as a glass substrate. For this reason, when bonding a polarizing plate to a liquid crystal glass cell etc., the adhesiveness between an adhesive and a liquid crystal glass cell becomes more favorable, for example.

  The silane coupling agent (D) is an organosilicon compound having at least one alkoxysilyl group in the molecule, having good compatibility with the pressure-sensitive adhesive component, and having light transparency, for example, substantially transparent Are suitable. It is preferable that the compounding quantity of such a silane coupling agent (D) is 0.01-1.0 mass part with respect to 100 mass parts of (meth) acrylic acid ester polymer (A), and is 0.8. It is preferable that it is 05-0.5 mass part.

  Specific examples of the silane coupling agent (D) include polymerizable unsaturated group-containing silicon compounds such as vinyltrimethoxysilane, vinyltriethoxysilane, and methacryloxypropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, Silicon compounds having an epoxy structure such as 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane and other amino group-containing silicon compounds, 3-mercaptopropyltrimethoxysilane and other thiol group-containing silicon compounds, and 3-chloropropyltrimethoxysilane and other halogenated alkyl groups Containing silicon compound, 3 Isocyanato group-containing silane compound such as isocyanate propyl triethoxysilane, hydrolyzate of the silane compound, such as the silane compound and the co-hydrolyzate of a tetraalkoxysilane such as tetraethoxysilane and the like. These may be used individually by 1 type and may be used in combination of 2 or more type.

  The pressure-sensitive adhesive composition P preferably does not contain a thermal crosslinking type crosslinking agent that requires aging after formation of the pressure-sensitive adhesive layer, for example, an isocyanate-based crosslinking agent or an epoxy-based crosslinking agent. On the other hand, it is preferable to contain a crosslinking agent that does not require aging after formation of the pressure-sensitive adhesive layer, for example, an aziridine-based crosslinking agent.

  In the adhesive composition P, if desired, various additives usually used for acrylic adhesives, such as tackifiers, antistatic agents, antioxidants, ultraviolet absorbers, light stabilizers, softeners, fillings An agent, a refractive index adjusting agent, etc. can be added.

  Here, usually, when the adhesive composition contains an antistatic agent, the resulting adhesive sheet often has insufficient durability. However, even if the pressure-sensitive adhesive composition P contains an antistatic agent, the pressure-sensitive adhesive sheet obtained using the pressure-sensitive adhesive composition P can exhibit excellent durability with respect to the glass substrate. it can.

  In addition, as an antistatic agent, if it is a well-known thing, it can be used without a restriction | limiting in particular. From the viewpoint of most preferable compatibility with the other components of the adhesive composition P, the cationic species is preferably lithium, potassium, amine, or pyridinium, and the anionic species is bisperfluoro. Any salt of alkylsulfonylimide, bisperfluorosulfonylimide, and hexafluorophosphate is preferred. Specifically, 1-butyl-4-methylpyridinium hexafluorophosphate and the like are preferable.

[Method for producing adhesive composition]
Adhesive composition P manufactures (meth) acrylic acid ester polymer (A), and mixes the obtained (meth) acrylic acid ester polymer (A) and active energy ray-curable component (B). In addition, if desired, it can be produced by adding a photopolymerization initiator (C), a silane coupling agent (D) or the like at an arbitrary stage.

  The (meth) acrylic acid ester polymer (A) can be produced by a normal 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 the organic peroxide 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 solution of the polymer (A) and the solution of the active energy ray-curable component (B) are mixed, and a diluting solvent is added if desired. Thereafter, if desired, a photopolymerization initiator (C), a silane coupling agent (D), and the like are added and mixed thoroughly to obtain a pressure-sensitive adhesive composition (coating solution) diluted with a solvent.

  Examples of the dilution solvent for diluting the adhesive composition to form a coating solution include aliphatic hydrocarbons such as hexane, heptane, and cyclohexane, aromatic hydrocarbons such as toluene and xylene, methylene chloride, and ethylene chloride. Halogenated hydrocarbons, alcohols such as methanol, ethanol, propanol, butanol and 1-methoxy-2-propanol, ketones such as acetone, methyl ethyl ketone, 2-pentanone, isophorone and cyclohexanone, esters such as ethyl acetate and butyl acetate, ethyl cellosolve A cellosolve solvent such as 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 an adhesive composition may be 10-40 mass%. In addition, when obtaining an application | coating solution, addition of a dilution solvent etc. is not a necessary condition, and if a viscosity etc. which can be coated with an adhesive composition, it is not necessary to add a dilution solvent. In this case, the adhesive composition becomes the coating solution as it is.

[Adhesive]
The pressure-sensitive adhesive according to this embodiment can be preferably obtained by applying the pressure-sensitive adhesive composition P to a desired object and drying it, and then curing the pressure-sensitive adhesive composition P by irradiation with active energy rays.

  Although drying of the adhesive composition P may be performed by air drying, it is normally performed by heat processing (preferably hot air drying). 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 10 seconds to 10 minutes, particularly preferably 50 seconds to 2 minutes.

As active energy rays, ultraviolet rays, electron beams and the like are usually used. The dose of the active energy ray varies depending on the type of the energy ray, for example, in the case of ultraviolet rays, preferably 50~1000mJ / cm ² in quantity, in particular 100 to 500 mJ / cm ² is preferred. In the case of an electron beam, about 10 to 1000 krad is preferable.

  By irradiation with the active energy ray, the plural active energy ray-curable components (B) are bonded to each other to form a three-dimensional network structure, and the plural (meth) acrylic acid ester polymers (A) It is presumed that the structure X is formed by being inserted into the network structure. At this time, since the adhesive composition P is rapidly cured, there is no need for aging, and various physical properties such as adhesive strength of the obtained adhesive are stabilized from the initial stage. As a result, it is possible to quickly carry out the shipment of the member having the pressure-sensitive adhesive layer made of the pressure-sensitive adhesive and the introduction of the next process, which is very advantageous in terms of the stock burden and productivity of the intermediate material.

  In addition, the pressure-sensitive adhesive according to this embodiment includes a (meth) acrylic acid ester polymer (A) containing a nitrogen atom-containing monomer as a constituent monomer unit, so that the substrate, in particular, a polarizing plate that has not been subjected to saponification treatment. With the structure X described above, excellent durability is exhibited. For example, when placed in a high temperature and high humidity of 80 ° C., 60 ° C. and 90% RH for 200 hours, or when a heat shock of −35 ° C. to 70 ° C. (each 30 minutes, 200 cycles) is given. , Floating, peeling, bubbles and the like are prevented / suppressed.

The pressure-sensitive adhesive according to this embodiment is immediately after formation of the pressure-sensitive adhesive layer (in consideration of the time lag until measurement, “immediately after formation of the pressure-sensitive adhesive layer” in this specification means within about half a day from irradiation with active energy rays). When the gel fraction is G1, and the gel fraction after storage for 7 days in an environment of 23 ° C. and 50% RH after forming the pressure-sensitive adhesive layer is G2, the following formula Gel fraction variation rate (%) = | (G2-G1) / G2 | × 100
The variation rate of the gel fraction calculated from the above is preferably 5% or less, particularly preferably 4.5% or less. The measuring method of a gel fraction is as showing to the test example mentioned later. As described above, the fact that the gel fraction fluctuation rate is within 5% indicates that the curing of the pressure-sensitive adhesive is substantially completed immediately after the pressure-sensitive adhesive layer is formed.

  The gel fraction G1 immediately after the formation of the pressure-sensitive adhesive layer and the gel fraction G2 after storage for 7 days are each preferably 30 to 90%, particularly preferably 50 to 80%. When the gel fraction is less than 30%, the cohesive force of the pressure-sensitive adhesive is insufficient, and durability and reworkability may be deteriorated. On the other hand, if the gel fraction exceeds 90%, the adhesive strength may be too low and the durability may be lowered.

  In the pressure-sensitive adhesive according to this embodiment, the difference between the pressure-sensitive adhesive force immediately after formation of the pressure-sensitive adhesive layer and the pressure-sensitive adhesive force after storage for 7 days in an environment of 23 ° C. and 50% RH after the pressure-sensitive adhesive layer formation is ± 3. It is preferably within 0.0N / 25 mm, particularly preferably within ± 2.5 N / 25 mm, and more preferably within ± 2.0 N / 25 mm. In addition, adhesive force here means 180 degree peeling adhesive force (peeling speed 300mm / min) according to JISZ0237, and after sticking to a to-be-adhered body and pressurizing at 0.5 MPa and 50 degreeC for 20 minutes. , Measured at 23 ° C. and 50% RH for 24 hours. When the adhesive force difference is within ± 3.0 N / 25 mm as described above, stable adhesive force is exhibited immediately after the formation of the adhesive layer.

  Moreover, the adhesive force of the pressure sensitive adhesive according to this embodiment is 0.1 to 0.1%, for example, with a polarizing plate as a base material, both immediately after forming the pressure sensitive adhesive layer and after storage for 7 days. It is preferable that it is 50N / 25mm, and it is especially preferable that it is 0.5-30N / 25mm. When the adhesive strength is within the above range, the adhesive sheet can be prevented from being lifted or peeled off from the glass substrate and excellent in reworkability.

  The storage elastic modulus (G ′) at 23 ° C. of the pressure-sensitive adhesive according to this embodiment is preferably 0.01 to 0.8 MPa, particularly preferably 0.05 to 0.6 MPa, and more preferably 0. It is preferably 0.07 to 0.1 MPa. When the storage elastic modulus (G ′) is in the above range, desired substrate adhesion and cohesive force can be obtained, and when applied to an optical member such as a polarizing plate, It is possible to effectively prevent floating or peeling at the interface with the glass substrate or the interface with the glass substrate. In addition, the storage elastic modulus in this specification is a value measured at 1 Hz using a viscoelasticity measuring device (in the test example, DYNAMIC ANALYZER RDA II manufactured by Rheometrics is used).

  The haze value (value measured according to JIS K7105) of the pressure-sensitive adhesive according to this embodiment is preferably 1.0% or less, particularly preferably 0.7% or less, and more preferably 0.5. % Or less is preferable. When the haze value is 1.0% or less, the transparency is very high, which is suitable for optical applications.

  The pressure-sensitive adhesive according to this embodiment can be preferably used for an optical member, particularly for a polarizing plate. For example, an adhesive between optical members such as a polarizing plate (polarizing film) and a retardation plate (retarding film), or It is suitable for adhesion between a polarizing plate (polarizing film) or a retardation plate (retardation film) and a glass substrate.

[Adhesive sheet]
As shown in FIG. 1, the pressure-sensitive adhesive sheet 1 </ b> A according to the first embodiment is laminated on the pressure-sensitive adhesive layer 11, the pressure-sensitive adhesive layer 11 stacked on the release surface of the release sheet 12, and the pressure-sensitive adhesive layer 11. And the formed base material 13.

  In addition, as shown in FIG. 2, the adhesive sheet 1B according to the second embodiment includes the two release sheets 12a and 12b and the two release sheets 12a and 12b so as to be in contact with the release surfaces of the two release sheets 12a and 12b. And the pressure-sensitive adhesive layer 11 sandwiched between the release sheets 12a and 12b. 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. .

  In any of the pressure-sensitive adhesive sheets 1A and 1B, the pressure-sensitive adhesive layer 11 is made of a pressure-sensitive adhesive formed by curing the above-described pressure-sensitive adhesive composition.

  The thickness of the pressure-sensitive adhesive layer 11 is appropriately determined according to the purpose of use of the pressure-sensitive adhesive sheets 1A and 1B, but is usually in the range of 5 to 100 μm, preferably 10 to 60 μm, for example, for optical members, particularly for polarizing plates. When used as an adhesive layer, it is preferably 10 to 50 μm, particularly preferably 15 to 30 μm.

  There is no restriction | limiting in particular as the base material 13, What was used as a base material sheet of a normal adhesive sheet can be used. For example, in addition to the desired optical member, woven or non-woven fabric using fibers such as rayon, acrylic, polyester, etc .; synthetic paper; paper such as fine paper, glassine paper, impregnated paper, coated paper; metal such as aluminum and copper Foil; Foam such as urethane foam and polyethylene foam; Polyester film such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyurethane film, polyethylene film, polypropylene film, cellulose film such as triacetyl cellulose, polyvinyl chloride film , Polyvinylidene chloride film, polyvinyl alcohol film, ethylene-vinyl acetate copolymer film, polystyrene film, polycarbonate film, acrylic resin film, norbornene resin film, cycloolefin Plastic film such as emission resin film; and the like of two or more kinds of those laminates. The plastic film may be uniaxially stretched or biaxially stretched.

  Examples of the optical member include a polarizing plate (polarizing film), a polarizer, a retardation plate (retarding film), a viewing angle compensation film, a brightness enhancement film, a contrast enhancement film, a liquid crystal polymer film, a diffusion film, and a transflective film. Etc. As the polarizing plate, it is preferable to use a polyvinyl alcohol polarizer on which both surfaces are bonded with a triacetyl cellulose (TAC) film. The pressure-sensitive adhesive layer 11 according to the present embodiment exhibits excellent adhesion to the above-mentioned base material, particularly a polarizing plate, and particularly exhibits excellent adhesion to a polarizing plate that has not been subjected to saponification treatment.

  Although the thickness of the base material 13 changes with kinds, for example in the case of an optical member, they are 10 micrometers-500 micrometers normally, Preferably they are 50 micrometers-300 micrometers.

  As the release sheets 12, 12a, 12b, for example, polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polyethylene naphthalate 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, polyimide film A fluororesin film or the like is used. These crosslinked films are also used. Furthermore, these laminated films may be sufficient. In addition, it is preferable that the release sheets 12, 12a, and 12b are active energy ray permeable.

  The release surface of the release sheet (particularly the surface in contact with the pressure-sensitive adhesive layer 11) is preferably subjected to a release treatment. Examples of the release agent used for the release treatment include alkyd, silicone, fluorine, unsaturated polyester, polyolefin, and wax release agents.

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

  In order to manufacture the pressure-sensitive adhesive sheet 1A, a solution (coating solution) containing the pressure-sensitive adhesive composition P is applied to the release surface of the release sheet 12 and dried to form a coating layer of the pressure-sensitive adhesive composition P. A base material 13 is laminated on the coating layer. Then, the adhesive layer 11 is formed by irradiating the coating layer with active energy rays through the release sheet 12. Aging is unnecessary after irradiation with active energy rays. The active energy ray irradiation conditions are as described above.

  Moreover, in order to manufacture the said adhesive sheet 1B, the coating solution containing the said adhesive composition is apply | coated and dried on the peeling surface of one peeling sheet 12a (or 12b), and the coating layer of the adhesive composition P Then, the other release sheet 12b (or 12a) is laminated on the coating layer. And the adhesive layer 11 is formed by irradiating the said coating-film layer with an active energy ray through the peeling sheet 12a (or 12b).

  Moreover, it replaces with forming an adhesive layer 11 by irradiating an active energy ray through a peeling sheet as mentioned above, and forms the coating-film layer of the adhesive composition P on a peeling sheet, The coating-film layer With the exposed state, the active energy ray may be irradiated to form the pressure-sensitive adhesive layer 11, and then a base material or a release sheet may be laminated on the pressure-sensitive adhesive layer 11. Furthermore, the adhesive layer 11 may be formed by directly forming a coating layer of the adhesive composition P on the substrate and irradiating the coating layer with active energy rays.

  As a method for applying the coating solution, 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.

  Here, for example, to manufacture a liquid crystal display device composed of a liquid crystal cell and a polarizing plate, a polarizing plate is used as the base material 13 of the pressure-sensitive adhesive sheet 1A, and the release sheet 12 of the pressure-sensitive adhesive sheet 1A is peeled off. What is necessary is just to bond the exposed adhesive layer 11 and a liquid crystal cell.

  For example, in order to manufacture a liquid crystal display device in which a retardation plate is disposed between a liquid crystal cell and a polarizing plate, as an example, first, one release sheet 12a (or 12b) of the adhesive sheet 1B is released. Then, the pressure-sensitive adhesive layer 11 exposed from the pressure-sensitive adhesive sheet 1B and the phase difference plate are bonded together. Next, the release sheet 12 of the pressure-sensitive adhesive sheet 1A using a polarizing plate as the base material 13 is peeled off, and the pressure-sensitive adhesive layer 11 exposed from the pressure-sensitive adhesive sheet 1A and the retardation plate are bonded. Furthermore, the other release sheet 12b (or 12a) is peeled from the pressure-sensitive adhesive layer 11 of the pressure-sensitive adhesive sheet B, and the pressure-sensitive adhesive layer 11 exposed from the pressure-sensitive adhesive sheet B is bonded to the liquid crystal cell.

  According to the above pressure-sensitive adhesive sheets 1A and 1B, since the pressure-sensitive adhesive layer 11 is excellent in durability, for example, when applied to the adhesion of a polarizing plate, it floats, peels off, foams, etc. even at high temperature or high temperature and high humidity. Is prevented / suppressed.

  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, the release sheet 12 of the adhesive sheet 1A may be omitted, or one of the release sheets 12a and 12b in the adhesive sheet 1B 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 polymer In a reaction vessel equipped with a stirrer, thermometer, reflux condenser, dropping device and nitrogen introduction tube, 78.4 parts by mass of n-butyl acrylate, 20 parts by mass of methoxyethyl acrylate , 1.5 parts by weight of 2-hydroxyethyl acrylate, 0.1 parts by weight of N, N-dimethylaminoethyl methacrylate, 200 parts by weight of ethyl acetate, and 0.08 parts by weight of 2,2′-azobisisobutyronitrile The air in the reaction vessel was replaced with nitrogen gas. While stirring in this nitrogen atmosphere, the reaction solution was heated to 60 ° C., reacted for 16 hours, and then cooled to room temperature. Here, the molecular weight of a part of the obtained solution was measured by a method described later, and production of a (meth) acrylic acid ester polymer (polymer (A)) having a weight average molecular weight of 1.3 million was confirmed.

2. Preparation of adhesive composition 100 parts by mass (solid content converted value; the same shall apply hereinafter) of the (meth) acrylic acid ester polymer (polymer (A)) obtained in the above step (1), and an active energy ray-curable component After mixing 5 parts by mass of tris (acryloxyethyl) isocyanurate (Aronix M-315, manufactured by Toagosei Co., Ltd.) as (B), benzophenone and 1-hydroxycyclohexyl phenyl ketone were used as the photopolymerization initiator (C). Hydrolyzed condensation of 3-mercaptopropyltrimethoxysilane-tetraethoxysilane as a silane coupling agent (D) 0.5 parts by mass (Ciba Specialty Chemicals, Irgacure 500) mixed at a mass ratio of 1: 1 (Shin-Etsu Chemical Co., Ltd., X-41-1810) 0.16 parts by mass, and 1-butyl as an antistatic agent A coating solution of the adhesive composition was obtained by adding 2.0 parts by mass of -4-methylpyridinium hexafluorophosphate (manufactured by Tokyo Chemical Industry Co., Ltd.), sufficiently stirring, and diluting with ethyl acetate.

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 acid ester polymer]
BA: n-butyl acrylate MEA: methoxyethyl acrylate HEA: 2-hydroxyethyl acrylate DM: N, N-dimethylaminoethyl methacrylate DMAEA: N, N-dimethylaminoethyl acrylate AA: acrylic acid

3. Production of polarizing plate with pressure-sensitive adhesive layer A release sheet (SP-PET3811, manufactured by Lintec Corporation, thickness: 38 μm) obtained by subjecting one surface of a polyethylene terephthalate film to a release treatment with a silicone-based release agent. After the coating was applied to the release-treated surface with a knife coater, the coating layer of the adhesive composition was formed by heat treatment at 90 ° C. for 1 minute.

Next, a polarizing plate that was not saponified was bonded to the exposed surface side of the coating layer. Then, the polarizing plate with an adhesive layer was obtained by irradiating an ultraviolet-ray on the following conditions through a peeling sheet, and making the said coating-film layer into an adhesive layer. In addition, the thickness of the adhesive layer was 20 μm.
<Ultraviolet irradiation conditions>
Fusion Co. electrodeless lamp H bulb used, illuminance 600 mW / cm ^2, light quantity 150 mJ / cm ²
・ Use UV-illumination meter "UVPF-36" manufactured by iGraphics.

[Examples 2 to 9, Comparative Examples 1 to 6]
Except for changing the type and ratio of each monomer constituting the (meth) acrylic acid ester polymer, and the amount of the active energy ray-curable component (B) and the photopolymerization initiator (C) as shown in Table 1, A polarizing plate with an adhesive layer was produced in the same manner as in Example 1. In Example 9 and Comparative Example 4, two types of (meth) acrylic acid ester polymers were used. In Comparative Examples 5 and 6, trimethylolpropane, which is a thermal crosslinking agent, was used as a component of the adhesive composition. Tolylene diisocyanate adduct (trade name “Coronate L” manufactured by Nippon Polyurethane Co., Ltd.) was used.

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 gel fraction)
Instead of the polarizing plate used for the production of the polarizing plate with the pressure-sensitive adhesive layer in the examples or comparative examples, a release sheet obtained by peeling one side of the polyethylene terephthalate film with a silicone release agent (manufactured by Lintec Corporation, SP-PET 3801, thickness) S: 38 μm) was used to prepare an adhesive sheet. Specifically, the release sheet is formed on the exposed coating layer of the release sheet / adhesive composition coating layer obtained in the production process of the example or comparative example. The layers were laminated so that the sides were in contact, and ultraviolet rays were irradiated through the release sheet under the same conditions as above. Thereby, the adhesive sheet which consists of a structure of a peeling sheet / adhesive layer / release sheet was produced. In addition, the thickness of the adhesive layer was 20 μm.

  The pressure-sensitive adhesive sheet produced as described above is sampled to a size of 80 mm × 80 mm immediately after production (after ultraviolet irradiation and half a day has passed), and the pressure-sensitive adhesive layer is wrapped in a polyester mesh (mesh size 200). The mass of only the adhesive was weighed with a precision balance. Further, the pressure-sensitive adhesive sheet prepared as described above was stored for 7 days under the conditions of 23 ° C. and 50% RH, and then the mass of the pressure-sensitive adhesive alone was weighed in the same manner as described above. Let these masses be M1.

  Next, the pressure-sensitive adhesive wrapped in the polyester mesh was immersed in ethyl acetate at room temperature (23 ° C.) for 24 hours. Thereafter, the pressure-sensitive adhesive was taken out, air-dried for 24 hours in an environment of a temperature of 23 ° C. and a relative humidity of 50%, and further dried in an oven at 80 ° C. for 12 hours. The mass of only the pressure-sensitive adhesive after drying was weighed with a precision balance. The mass at this time is M2.

From the obtained M1 and M2, the following formula Gel fraction (%) = (M2 / M1) × 100
The gel fraction G1 (%) immediately after preparation of the pressure-sensitive adhesive sheet (immediately after formation of the pressure-sensitive adhesive layer) and after storage for 7 days in an environment of 23 ° C. and 50% RH from the production of the pressure-sensitive adhesive sheet (pressure-sensitive adhesive layer formation) The gel fraction G2 (%) was calculated.

Further, from the obtained G1 and G2, the following formula Gel fraction variation rate (%) = | (G2-G1) / G2 | × 100
Was used to calculate the gel fraction fluctuation rate (%). The results are shown in Table 2.

[Test Example 2] (Measurement of adhesive strength)
The pressure-sensitive adhesive layer-attached polarizing plate obtained in Examples or Comparative Examples was cut to prepare samples having a width of 25 mm and a length of 100 mm. As samples, those immediately after the production of the polarizing plate with the pressure-sensitive adhesive layer (immediately after the formation of the pressure-sensitive adhesive layer, that is, within about half a day from the ultraviolet irradiation) and those prepared from the production of the polarizing plate with the pressure-sensitive adhesive layer (formation of the pressure-sensitive adhesive layer) What was prepared after being stored in an RH environment for 7 days was prepared. After peeling the release sheet from these samples and pasting the sample on non-alkali glass (Corning, Eagle XG) through the exposed adhesive layer, 0.5 MPa at 50 ° C. in an autoclave manufactured by Kurihara Seisakusho, Pressurized for 20 minutes. Then, after leaving for 24 hours under conditions of 23 ° C. and 50% RH, using a tensile tester (Orientec, Tensilon), the pressure-sensitive adhesive layer under the conditions of a peeling speed of 300 mm / min and a peeling angle of 180 °. The adhesive strength immediately after formation (S1: N / 25 mm) and the adhesive strength after storage for 7 days (S2: N / 25 mm) were measured. Moreover, the adhesive force difference ((DELTA) S) which subtracted the adhesive force immediately after formation of an adhesive layer from the adhesive force after 7-day storage was computed. The results are shown in Table 2.

[Test Example 3] (Durability evaluation)
The pressure-sensitive adhesive layer-attached polarizing plate obtained in Examples or Comparative Examples was cut to produce a sample having a size of 233 mm × 309 mm. Samples were prepared immediately after the production of the polarizing plate with the pressure-sensitive adhesive layer (immediately after the formation of the pressure-sensitive adhesive layer) (H1) and from the production of the polarizing plate with the pressure-sensitive adhesive layer (formation of the pressure-sensitive adhesive layer) in an environment of 23 ° C. and 50% RH. (H2) was prepared after storage for 7 days. After peeling off the release sheet from these samples and pasting it on alkali-free glass (Corning Corp., Eagle XG) via the exposed adhesive layer, it was added at 0.5 MPa and 50 ° C. for 20 minutes in an autoclave manufactured by Kurihara Seisakusho. Pressed.

Then, it put in the environment of the following durable conditions, and observed using the 10 time loupe 200 hours later. Appearance change was based on the following. The results for each of the H1 and H2 samples are shown in Table 2.
A: No defects on 4 sides. O: No defects on the sides of 0.6 mm or more from the outer peripheral edge on 4 sides. X: 0.6 mm or more from the outer edge on at least one side of the four sides. There are abnormal appearance defects of adhesives of 0.1 mm or more such as floating, peeling, foaming, streaks, etc. <durability conditions>
・ 80 ℃ dry
・ 60 ℃, relative humidity 90% RH
-Heat shock test for 30 minutes each at -35 ° C to 70 ° C, 200 cycles

[Test Example 4] (Measurement of storage elastic modulus)
In the same manner as in Test Example 1, a pressure-sensitive adhesive sheet composed of a release sheet / pressure-sensitive adhesive layer / release sheet was produced. The release sheet was peeled from the pressure-sensitive adhesive sheet, and a plurality of pressure-sensitive adhesive layers were laminated to a thickness of 3 mm. A cylindrical body (height 3 mm) having a diameter of 8 mm was punched out from the obtained laminate of the pressure-sensitive adhesive layer, and this was used as a sample.

About the said sample, based on JISK7244-6, the storage elastic modulus (MPa) was measured on condition of the following by the torsional shear method using the viscoelasticity measuring device (the REOMETRIC company make, DYNAMIC ANALAYZER). The results are shown in Table 2.
Measurement frequency: 1Hz
Measurement temperature: 23 ° C

[Test Example 5] (Measurement of surface resistance)
The pressure-sensitive adhesive layer-attached polarizing plate obtained in Examples or Comparative Examples was cut into a size of 50 mm × 50 mm, and the obtained sample was allowed to stand at a temperature of 23 ° C. and a humidity of 50% RH for 24 hours. Thereafter, the release sheet is peeled off, and the exposed adhesive layer surface is subjected to a surface resistance value (Ω / sq) according to JIS K6911 using a resistivity meter (manufactured by Mitsubishi Chemical Analytech Co., Ltd., Hiresta UP MCP-HT450 type). ) Was measured. The results are shown in Table 2.

The surface resistance value is preferably 3.0 × 10 ¹¹ Ω / sq or less, particularly preferably 1.0 × 10 ¹¹ Ω / sq or less, and more preferably 8.0 × 10 ¹⁰ Ω / sq. It is preferably sq or less. When the surface resistance value is not more than the above value, good antistatic properties can be exhibited.

  As is clear from Table 2, the pressure-sensitive adhesives of the pressure-sensitive adhesive layers obtained in the examples have a minute change in gel fraction and pressure-sensitive adhesive force immediately after the pressure-sensitive adhesive layer formation and after storage for 7 days, and are durable. It was also excellent in performance.

  The pressure-sensitive adhesive of the present invention is suitable for adhesion of optical members, particularly polarizing plates, and the pressure-sensitive adhesive sheet of the present invention is suitable as a pressure-sensitive adhesive sheet for optical members, particularly for polarizing plates.

1A, 1B ... Adhesive sheet 11 ... Adhesive layer 12, 12a, 12b ... Release sheet 13 ... Base material

Claims (9)

A pressure-sensitive adhesive sheet comprising a base material and a pressure-sensitive adhesive layer,
The pressure-sensitive adhesive layer is
(Meth) acrylic acid ester polymer (A) having a weight average molecular weight of 600,000 to 2,000,000 and containing a monomer having a nitrogen atom as a monomer unit constituting the polymer;
An active energy ray-curable component (B),
Does not contain a thermal cross-linking agent,
The monomer having a nitrogen atom is a monomer having a tertiary amino group;
The active energy ray-cured product of the adhesive composition in which the ratio of the active energy ray-curable component (B) to 100 parts by mass of the (meth) acrylic acid ester polymer (A) is 1 to 20 parts by mass. Made of adhesive
A pressure-sensitive adhesive sheet. 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;
An adhesive sheet comprising
The pressure-sensitive adhesive layer is
(Meth) acrylic acid ester polymer (A) having a weight average molecular weight of 600,000 to 2,000,000 and containing a monomer having a nitrogen atom as a monomer unit constituting the polymer;
An active energy ray-curable component (B) and
Containing
Does not contain a thermal cross-linking agent,
The monomer having a nitrogen atom is a monomer having a tertiary amino group;
The ratio of the active energy ray-curable component (B) to 100 parts by mass of the (meth) acrylic acid ester polymer (A) is 1 to 20 parts by mass.
It consists of a pressure-sensitive adhesive that is a cured product of active energy rays.
A pressure-sensitive adhesive sheet. Monomer having a tertiary amino group, acrylic acid N, N- dimethylaminoethyl and methacrylic acid N, according to claim 1 or 2, characterized in that at least one selected from N- dimethylaminoethyl Adhesive sheet. The said (meth) acrylic acid ester polymer (A) contains 0.01-5.0 mass% of monomers which have the said nitrogen atom as a monomer unit which comprises the said polymer. The adhesive sheet as described in any one of -3. The pressure-sensitive adhesive sheet according to any one of claims 1 to 4 , wherein the pressure-sensitive adhesive composition further contains a photopolymerization initiator (C) . The pressure-sensitive adhesive sheet according to claim 5 , wherein the content of the photopolymerization initiator (C) is 2 to 15 parts by mass with respect to 100 parts by mass of the active energy ray-curable component (B). . The pressure-sensitive adhesive sheet according to claim 1, wherein the pressure-sensitive adhesive has a storage elastic modulus (G ′) at 23 ° C. of 0.01 to 0.8 MPa . The pressure-sensitive adhesive sheet according to claim 1 , wherein the base material is an optical member. The pressure-sensitive adhesive sheet according to claim 8 , wherein the optical member is a polarizing plate.

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