JP2013213085A - Pressure-sensitive adhesive composition, pressure-sensitive adhesive and pressure-sensitive adhesive sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pressure sensitive adhesive composition, a pressure-sensitive adhesive and a pressure-sensitive adhesive sheet easy to handle, not requiring aging after the formation of a pressure-sensitive adhesive layer, and having excellent follow-up capability to a rough surface.SOLUTION: A pressure sensitive adhesive composition contains: a (meth)acrylic ester polymer (A) with a weight average molecular weight of 300,000-2,000,000; and a reactive (meth)acrylic ester polymer (B) with a weight average molecular weight of 10,000-100,000 having a polymerizable double bond in a side chain thereof. The proportion of the reactive (meth)acrylic ester polymer (B) to 100 pts.mass of the (meth)acrylic ester polymer (A) is 5-50 pts.mass. The reactive (meth)acrylic ester polymer (B) is obtained by reacting a (meth)acrylic ester polymer (b1) containing 5-30 mass% of a functional group (x)-containing monomer as a constituent monomer unit with a polymerizable double bond-containing compound (b2) having a substituent (y) which reacts with the functional group (x), wherein the molar equivalent of the substituent (y) to the functional group (x) is 0.1-0.6.

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.

  A polarizing plate is generally composed of a film having a three-layer structure in which an optically isotropic film such as a triacetyl cellulose (TAC) film is bonded to both sides of a polyvinyl alcohol polarizer, and further on one side. Is provided with an adhesive layer for the purpose of sticking to the transparent electrode substrate or 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, with an isocyanate-based crosslinking agent, an epoxy-based crosslinking agent, or the like, crosslinking is not completed after coating and drying, and aging usually takes about 3 days to 1 week thereafter for complete crosslinking.

  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.

  On the other hand, in recent years, liquid crystal panels have been made thinner, and for this reason, liquid crystal cells have been thinned by mechanical polishing. Although the surface of the liquid crystal cell is roughened by such mechanical polishing, in order to ensure adhesion between the liquid crystal cell having the roughened surface and the pressure-sensitive adhesive layer, the surface of the roughened surface has excellent unevenness followability. There is a need for an adhesive.

  In addition to polarizing plate applications, a pressure-sensitive adhesive layer is laminated on the surface of a transparent conductive film provided with a patterned transparent conductive layer without the inclusion of bubbles or the like, or has a patterned step on the surface of a hard coat film. Provided with a printed layer, the adhesive layer is laminated on the surface without air bubbles, and the unevenness in the unevenness is excellent in various applications such as filling the step with the light shielding layer corresponding to the frame part of the mobile phone monitor with the adhesive layer. An adhesive is desired.

  In order to shorten the aging period, for example, in a thermal crosslinking system, a compound causing keto-enol tautomerism is added (Patent Document 1), a dialkylacetylacetone tin complex catalyst is added (Patent Document 2), or a main polymer. Various studies have been made such as introducing a specific hydroxyalkyl vinyl ether monomer as a structural unit (Patent Document 3).

  Moreover, in an active energy ray hardening type | system | group, by using the adhesive composition containing the acrylic polymer (A) and the acrylic polymer (B) which has a radiation polymerizable group in a side chain in patent document 4, It is disclosed that the aging period is shortened.

Japanese Patent No. 4623485 JP 2008-013634 A JP 2011-246711 A Japanese Patent No. 3921017

  However, the methods of Patent Documents 1 to 3 are still insufficient from the viewpoint of shortening the aging period. In addition, the method of Patent Document 4 is effective in terms of shortening the aging period, but has a problem that it is inferior in unevenness followability because it uses a so-called hard adhesive peculiar to the active energy ray-curable adhesive. .

  The present invention has been made in view of such a situation, is easy to handle, does not require aging after the formation of the pressure-sensitive adhesive layer, and is a pressure-sensitive adhesive composition and pressure-sensitive adhesive excellent in unevenness followability And it aims at providing an adhesive sheet.

  In order to achieve the above object, first, the present invention has a (meth) acrylic acid ester polymer (A) having a weight average molecular weight of 300,000 to 2,000,000 and a weight average molecular weight of 10,000 to 100,000. And a reactive (meth) acrylic acid ester polymer (B) having a polymerizable double bond in the side chain, the (meth) acrylic acid ester polymer (A) 100 mass The ratio of the reactive (meth) acrylic acid ester polymer (B) to 5 parts by weight is 5 to 50 parts by mass, and the reactive (meth) acrylic acid ester polymer (B) contains a functional group (x). A polymerizable (meth) acrylic ester polymer (b1) containing 5 to 30% by mass of monomer as a constituent monomer unit, and a polymerizable double bond-containing compound having a substituent (y) that reacts with the functional group (x) ( obtained by reacting with b2) Is intended to be, molar equivalents of the substituents (y) with respect to the functional groups (x), provides an adhesive composition characterized in that 0.1 to 0.6 (Invention 1).

  The pressure-sensitive adhesive composition according to the invention (Invention 1) is easy to handle because the curing (crosslinking) reaction does not proceed before irradiation with active energy rays, and the pressure-sensitive adhesive layer is irradiated with active energy rays. Since the curing of the pressure-sensitive adhesive is substantially completed immediately after the formation, aging is unnecessary. In the pressure-sensitive adhesive obtained by curing the pressure-sensitive adhesive composition according to the invention (Invention 1), low molecular weight polymers are bonded to each other to form a three-dimensional network structure, and the three-dimensional network structure has a plurality of high molecular weights. By inserting the polymer, it is presumed that the high molecular weight polymers are bound to each other and a pseudo cross-linked structure is formed between the high molecular weight polymers. Thereby, the obtained adhesive exhibits excellent durability even at high temperatures or high temperatures and high humidity while being excellent in unevenness followability.

  The pressure-sensitive adhesive according to the invention (Invention 1) preferably further contains a photopolymerization initiator (C) (Invention 2).

  In the said invention (invention 2), content of the said photoinitiator (C) is 5-30 mass parts with respect to 100 mass parts of said reactive (meth) acrylic acid ester polymers (B). Is preferred (Invention 3).

  In the said invention (invention 1-3), the said adhesive composition contains an aziridine type crosslinking agent (D) further, The said (meth) acrylic acid ester polymer (A) is a monomer which comprises the said polymer. It is preferable to contain a functional group-containing monomer having a functional group capable of reacting with the aziridinyl group of the aziridine-based crosslinking agent (D) as a unit (Invention 4).

  In the said invention (invention 4), it is preferable that the said functional group is a carboxyl group (invention 5).

  In the above inventions (Inventions 4 and 5), the content of the aziridine crosslinking agent (D) is such that the aziridinyl group of the aziridine crosslinking agent (D) is the functional group in the (meth) acrylic acid ester polymer (A). It is preferable that it is the quantity used as 0.001-0.1 molar equivalent with respect to group (invention 6).

  The pressure-sensitive adhesive according to the above invention (Inventions 1 to 6) preferably further contains a silane coupling agent (E) (Invention 7).

  In the said invention (invention 7), content of the said silane coupling agent (E) is 0.01-1.0 mass part with respect to 100 mass parts of said (meth) acrylic acid ester polymers (A). There is preferably (Invention 8).

  2ndly this invention provides the adhesive which hardens the said adhesive composition (invention 1-8) by irradiation of an active energy ray (invention 9).

In the said invention (invention 9), it is preferable that the irradiation amount of the said active energy ray is 50-1000 mJ / cm < ² > (invention 10).

  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 comprises the pressure-sensitive adhesive (Invention 9 and 10). (Invention 11).

  In the said invention (invention 11), it is preferable that the said base material is an optical member (invention 12).

  Thirdly, 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 9 and 10) (Invention 13).

  The adhesive composition according to the present invention is easy to handle because the curing (crosslinking) reaction does not proceed before irradiation with active energy rays. Further, since 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, aging is unnecessary, and various physical properties of the pressure-sensitive adhesive are stabilized immediately after the pressure-sensitive adhesive layer is formed. 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, in the pressure-sensitive adhesive obtained by curing the pressure-sensitive adhesive composition according to the present invention, a low molecular weight polymer that has been conventionally used as a plasticizer is bonded to each other to form a three-dimensional network structure. It is presumed that by inserting a plurality of high molecular weight polymers into the network structure, the high molecular weight polymers are constrained to form a pseudo cross-linked structure between the high molecular weight polymers. Thereby, the obtained adhesive exhibits excellent durability even at high temperatures or high temperatures and high humidity while being excellent in unevenness followability.

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 (hereinafter referred to as “pressure-sensitive adhesive composition P”) according to the present embodiment has a (meth) acrylic acid ester polymer (A) (hereinafter simply referred to as “the pressure-sensitive adhesive composition P”) having a weight average molecular weight of 300,000 to 2,000,000. Polymer (A) "), and a reactive (meth) acrylic acid ester polymer (B) having a weight average molecular weight of 10,000 to 100,000 and having a polymerizable double bond in the side chain ( Hereinafter, the photopolymerization initiator (C), the aziridine-based crosslinking agent (D), or the silane coupling agent (E) may be further added. contains. 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 an active energy ray, a plurality of low molecular weight polymers (B) are quickly bonded to each other by cleavage of a polymerizable double bond in a side chain, thereby forming a three-dimensional network structure. Form. A plurality of high molecular weight polymers (A) are inserted into the three-dimensional network structure and constrained, and a pseudo-crosslinked structure (constrained but covalently bonded between the high molecular weight polymers (A)). It is presumed that an unstructured structure is formed (the entire structure is 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. Furthermore, the obtained pressure-sensitive adhesive layer is excellent in uneven followability, and also exhibits excellent durability without being floated, peeled off, foamed or the like even under high temperature or high temperature and high humidity. This is considered to be due to the above structure X.

  The (meth) acrylic acid ester polymer (A) is a (meth) acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms, an alkoxyalkyl group-containing (meth) acrylic acid ester optionally used, and, if desired, A copolymer of a monomer having a functional group to be used (functional group-containing monomer) and another monomer used as desired is preferable. The (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms of the alkyl group and the alkoxyalkyl group-containing (meth) acrylic acid ester can impart desired adhesive force to the obtained pressure-sensitive adhesive. It is considered that the functional group-containing monomer can effectively insert the polymer (A) into the three-dimensional network structure of the polymer (B) depending on the polarity of the functional group. Moreover, when it has a functional group-containing monomer as a constituent monomer unit, it is possible to form an actual non-pseudo crosslinked structure by the polymer (A) via the aziridine-based crosslinking agent (D) as will be described later. Become.

  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, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, n- (meth) acrylate Examples include decyl, n-dodecyl (meth) acrylate, myristyl (meth) acrylate, palmityl (meth) acrylate, stearyl (meth) acrylate, and the like. These may be used alone or in combination of two or more.

  Examples of the alkoxyalkyl group-containing (meth) acrylic acid ester include methoxymethyl (meth) acrylate, methoxyethyl (meth) acrylate, methoxypropyl (meth) acrylate, methoxybutyl (meth) acrylate, (meth) Examples include ethoxymethyl acrylate, ethoxyethyl (meth) acrylate, ethoxypropyl (meth) acrylate, ethoxybutyl (meth) acrylate, and the like. These may be used alone or in combination of two or more. In addition, it is preferable that carbon number of an alkoxyalkyl group is about 20 or less.

  As functional group-containing monomers, monomers having a hydroxyl group in the molecule (hydroxyl group-containing monomer), monomers having a carboxyl group in the molecule (carboxyl group-containing monomer), monomers having an amino group in the molecule (amino group-containing monomer), etc. Are preferable, and one kind can be used alone, or two or more kinds 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. In addition, when the adhesive composition P contains an aziridine type crosslinking agent (D), since a carboxyl group is excellent in the reactivity with the aziridinyl group of an aziridine type crosslinking agent (D), (meth) acrylic acid ester polymer ( A) preferably has at least a carboxyl group-containing monomer as a constituent monomer unit.

  Examples of the amino group-containing monomer include aminoethyl (meth) acrylate, n-butylaminoethyl (meth) acrylate, and the like. These may be used alone or in combination of two or more.

  Examples of the other monomer include (meth) acrylic acid ester having an aliphatic ring such as cyclohexyl (meth) acrylate, (meth) acrylic acid ester having an aromatic ring such as phenyl (meth) acrylate, and acrylamide. Non-crosslinkable tertiary amino groups such as non-crosslinkable (meth) acrylamide such as methacrylamide, N, N-dimethylaminoethyl (meth) acrylate and N, N-dimethylaminopropyl (meth) acrylate Examples include (meth) acrylic acid ester, vinyl acetate, and styrene. These may be used alone or in combination of two or more.

  The (meth) acrylic acid ester polymer (A) is a (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms and an alkoxyalkyl group-containing (meth) acrylic acid as a monomer unit constituting the polymer. It is preferable to contain 70 to 99% by mass in combination with the ester, particularly preferably 80 to 98% by mass, and more preferably 95.0 to 97.0% by mass. When the total content of the (meth) acrylic acid alkyl ester and the alkoxyalkyl group-containing (meth) acrylic acid ester is within the above range, an appropriate adhesive force as an adhesive can be obtained. Moreover, if the total content of the (meth) acrylic acid alkyl ester and the alkoxyalkyl group-containing (meth) acrylic acid ester is less than 70% by mass, the adhesive strength may be too low. The (meth) acrylic acid ester polymer (A) may be composed of only a (meth) acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms and an alkoxyalkyl group-containing (meth) acrylic acid ester. Good.

  Here, when using together the (meth) acrylic-acid alkylester whose carbon number of an alkyl group is 1-20, and the alkoxyalkyl group containing (meth) acrylic acid ester, the carbon number of the alkyl group in both is 1-20 (meta) ) The proportion of acrylic acid alkyl ester is preferably 50% by mass or more, particularly preferably 60% by mass or more, and further preferably 70% by mass or more. In addition, as an upper limit of the said mixture ratio of both, 100 mass% of (meth) acrylic-acid alkylesters whose carbon number of an alkyl group is 1-20 may be sufficient.

  The (meth) acrylic acid ester polymer (A) preferably contains 1.0 to 20.0% by mass of the functional group-containing monomer as a monomer unit constituting the polymer, particularly 2.0 to The content is preferably 10.0% by mass, and more preferably 3.0 to 5.0% by mass. By containing the functional group-containing monomer within the above range, compatibility with the reactive (meth) acrylic acid ester polymer (B) is improved, and the structure X can be efficiently formed. An adhesive having excellent properties can be obtained.

  When the adhesive composition P contains an aziridine-based crosslinking agent (D), the (meth) acrylic acid ester polymer (A) has a carboxyl group-containing monomer as a monomer unit constituting the polymer, 1.0 It is preferable to contain-10.0 mass%, and it is especially preferable to contain 3.0-5.0 mass%. Thereby, the polymer (A) can favorably form a crosslinked structure via the aziridine-based crosslinking agent (D).

  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 300,000 to 2,000,000, preferably 600,000 to 1,800,000, particularly preferably 700,000 to 1,500,000. That is, the (meth) acrylic acid ester polymer (A) is a high molecular weight polymer component. In addition, the weight average molecular weight in this specification is the value of polystyrene conversion measured by the gel permeation chromatography (GPC) method.

  The (meth) acrylic acid ester polymer (A) has a weight average molecular weight within the above range, and the polymer (A) has a relatively large molecular weight, so that the structure X is presumably formed. The

  Here, when the weight average molecular weight of the (meth) acrylic acid ester polymer (A) is less than 300,000, the gel fraction of the resulting pressure-sensitive adhesive may be low and the durability may be poor. Moreover, when the weight average molecular weight of (meth) acrylic acid ester polymer (A) exceeds 2 million, compatibility with a reactive (meth) acrylic acid ester polymer (B) etc. will deteriorate, and the adhesive obtained As the haze value increases, the durability may decrease.

  In the adhesive composition P, the (meth) acrylic acid ester polymer (A) may be used singly or in combination of two or more.

  The reactive (meth) acrylate polymer (B) having a polymerizable double bond in the side chain includes a (meth) acrylate polymer (b1) having a functional group (x) -containing monomer as a constituent monomer unit. And a polymerizable double bond-containing compound (b2) having a substituent (y) that reacts with the functional group (x).

  The (meth) acrylic acid ester polymer (b1) is a functional group (x) -containing monomer, a (meth) acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms, and other optionally used. Copolymers with these monomers are preferred.

  The functional group (x) -containing monomer is a monomer having a polymerizable double bond and a functional group such as a hydroxyl group, a carboxyl group, an amino group, a substituted amino group, and an epoxy group in the molecule, preferably a hydroxyl group-containing monomer. An unsaturated compound and / or a carboxyl group-containing unsaturated compound is used.

  Specific examples of such functional group (x) -containing monomers include hydroxyl group-containing (meth) acrylates such as 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, Examples include carboxyl group-containing compounds such as acrylic acid, methacrylic acid, and itaconic acid, and these are used alone or in combination of two or more.

  As the (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group and other monomers, those similar to the (meth) acrylic acid ester polymer (A) can be used.

  The (meth) acrylic acid ester polymer (b1) is usually 3 to 100% by mass, preferably 5 to 40% by mass, particularly preferably the above functional group (x) -containing monomer as a monomer unit constituting the polymer. It is contained in a proportion of 10 to 30% by mass, and the structural unit derived from the alkyl group (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms is usually 0 to 97% by mass, preferably 60 to 95% by mass, Especially preferably, it contains in the ratio of 70-90 mass%.

  In addition, the functional group containing monomer which is a constituent monomer of the (meth) acrylic acid ester polymer (A) and the functional group (x) containing monomer which is a constituent monomer of the (meth) acrylic acid ester polymer (b1) Are preferably different from each other, for example, a carboxyl group-containing monomer and a hydroxyl group-containing monomer. Thereby, an aziridine type crosslinking agent (D) and a silane coupling agent (E) can be made to act only on the polymer (A).

  On the other hand, the substituent (y) of the polymerizable double bond-containing compound (b2) is the type of the functional group (x) of the functional group (x) -containing monomer unit of the (meth) acrylic acid ester polymer (b1). Can be selected as appropriate. For example, when the functional group (x) is a hydroxyl group, an amino group or a substituted amino group, the substituent (y) is preferably an isocyanate group or an epoxy group, and when the functional group (x) is a carboxyl group, the substituent (y) Is preferably an aziridinyl group, an epoxy group or an oxazolinyl group. When the functional group (x) is an epoxy group, the substituent (y) is preferably an amino group, a carboxyl group or an aziridinyl group. One such substituent (y) is included for each molecule of the polymerizable double bond-containing compound (b2).

  The polymerizable double bond-containing compound (b2) usually contains 1 to 5 and preferably 1 to 2 polymerizable double bonds (carbon-carbon double bonds) per molecule. Examples of such a polymerizable double bond-containing compound (b2) include (meth) acryloyloxyethyl isocyanate, meta-isopropenyl-α, α-dimethylbenzyl isocyanate, (meth) acryloyl isocyanate, allyl isocyanate; Or (meth) acryloyl monoisocyanate compound obtained by reaction of polyisocyanate compound and hydroxyethyl (meth) acrylate; obtained by reaction of diisocyanate compound or polyisocyanate compound, polyol compound and hydroxyethyl (meth) acrylate (Meth) acryloyl monoisocyanate compound; glycidyl (meth) acrylate; (meth) acrylic acid, 2- (1-aziridinyl) ethyl (meth) acrylate And 2-vinyl-2-oxazoline, 2-isopropenyl-2-oxazoline and the like.

  As the polymerizable double bond-containing compound (b2), among them, the group having an isocyanate group as the substituent (y) and containing a polymerizable double bond, a group containing an ethylenic double bond, A compound having a (meth) acryloyl group is particularly preferable, and specifically, (meth) acryloyloxyethyl isocyanate, particularly methacryloyloxyethyl isocyanate is preferable.

  The abundance of the polymerizable double bond-containing compound (b2) as the substituent (y) in the reactive (meth) acrylate polymer (B) is the functionality of the (meth) acrylate polymer (b1). It is 0.1-0.6 molar equivalent with respect to the abundance of the functional group (x) of a group (x) containing monomer, Preferably it is 0.2-0.5 molar equivalent.

  The reaction between the (meth) acrylic acid ester polymer (b1) and the polymerizable double bond-containing compound (b2) is usually at normal pressure, under an inert gas atmosphere, at room temperature or at a temperature of 40 to 70 ° C., The reaction is carried out in an organic solvent such as ethyl acetate for about 12 to 48 hours. In the reaction, a catalyst, a polymerization inhibitor or the like can be appropriately used. For example, in the case of a reaction between a (meth) acrylic acid ester polymer (b1) in which the functional group (x) is a hydroxyl group and a polymerizable double bond-containing compound (b2) in which the substituent (y) is an isocyanate group It is preferable to use an organic tin catalyst such as dibutyltin laurate. Further, depending on the combination of the functional group (x) and the substituent (y), the reaction temperature, pressure, solvent, time, presence / absence of catalyst, and type of catalyst can be selected as appropriate. As a result, the functional group (x) present in the (meth) acrylic acid ester polymer (b1) reacts with the substituent (y) in the polymerizable double bond-containing compound (b2) to form a side chain. A reactive (meth) acrylic acid ester polymer (B) into which a polymerizable double bond has been introduced is obtained. The reaction rate of the functional group (x) and the substituent (y) in this reaction is usually 70% or more, preferably 80% or more, and the unreacted functional group (x) is a reactive (meth) acrylate. It may remain in the polymer (B).

  The polymerization mode of the reactive (meth) acrylic acid ester polymer (B) ((meth) acrylic acid ester polymer (b1)) may be a random copolymer or a block copolymer. Good.

  The weight average molecular weight of the reactive (meth) acrylic acid ester polymer (B) is 10,000 to 100,000, preferably 30,000 to 80,000, particularly preferably 40,000 to 60,000. That is, the reactive (meth) acrylic acid ester polymer (B) is a polymer component having a low molecular weight as compared with the (meth) acrylic acid ester polymer (A).

  When the weight average molecular weight of the reactive (meth) acrylic acid ester polymer (B) is within the above range, a three-dimensional network structure peculiar to the pressure-sensitive adhesive according to this embodiment is formed, contributing to excellent durability. Will be. That is, when the weight average molecular weight of the reactive (meth) acrylic acid ester polymer (B) is less than 10,000, a good three-dimensional network structure cannot be obtained, and durability may deteriorate. On the other hand, when the weight average molecular weight of the reactive (meth) acrylic acid ester polymer (B) exceeds 100,000, the compatibility with the (meth) acrylic acid ester polymer (A) is lowered and the optical properties are inferior. It may be a thing. Moreover, the restraint state of the polymer (A) in the three-dimensional network structure formed by the polymer (B) becomes insufficient, and as a result, the resulting pressure-sensitive adhesive may be inferior in durability.

  In the adhesive composition P, the reactive (meth) acrylic acid ester polymer (B) may be used alone or in combination of two or more.

  The blending ratio of the reactive (meth) acrylate polymer (B) to 100 parts by mass of the (meth) acrylate polymer (A) is preferably 5 to 50 parts by mass, particularly 7 to 45 parts by mass. It is preferable that it is 10-40 mass parts.

  The pressure-sensitive adhesive obtained from the pressure-sensitive adhesive composition P containing the (meth) acrylic acid ester polymer (A) and the reactive (meth) acrylic acid ester polymer (B) in the above proportions forms the structure X well. Presumed to be.

  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) as described above, the reactive (meth) acrylic acid ester polymer (B) can be efficiently cured, and the curing time and the amount of light 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.

  A photoinitiator (C) is 1.0-50 mass parts with respect to 100 mass parts of reactive (meth) acrylic acid ester polymer (B), Especially the range of 5.0-30.0 mass parts. It is preferably used in an amount.

  The pressure-sensitive adhesive composition P may contain a cross-linking agent as desired, but as the cross-linking agent, an aziridine-based cross-linking agent (D) that undergoes a rapid cross-linking reaction and does not require aging after formation of the pressure-sensitive adhesive layer. It is preferable to contain. In addition, an isocyanate type crosslinking agent and an epoxy type crosslinking agent often require aging after pressure-sensitive adhesive layer formation. When the adhesive composition P contains an aziridine-based crosslinking agent (D), the (meth) acrylic acid ester polymer (A) has a reactive functional group, particularly a carboxyl group (with the carboxyl group-containing monomer as a constituent monomer unit). Preferably). By reacting this reactive functional group with the aziridyl group of the aziridine-based crosslinking agent (D), the (meth) acrylic acid ester polymer (A) becomes pseudo via the aziridine-based crosslinking agent (D). There is no actual cross-linked structure. The crosslinked structure of this polymer (A) is the tertiary structure of the polymer (B) so that the polymer (A) is incorporated into the three-dimensional network structure formed by the reactive (meth) acrylate polymer (B). Presumed to be intertwined with the original network structure. The durability of the resulting pressure-sensitive adhesive is further improved by the network structure formed by the crosslinked structure of the polymer (A) and the three-dimensional network structure of the polymer (B).

  Examples of the aziridine-based crosslinking agent (D) include diphenylmethane-4,4′-bis (1-aziridinecarboxamide), trimethylolpropane tri-β-aziridinylpropionate, tetramethylolmethane tri-β- Aziridinylpropionate, toluene-2,4-bis (1-aziridinecarboxamide), triethylenemelamine, bisisophthaloyl-1- (2-methylaziridine), tris-1- (2-methylaziridine) ) Phosphine, trimethylolpropane tri-β- (2-methylaziridine) propionate and the like. These may be used alone or in combination of two or more.

  The content of the aziridine crosslinking agent (D) in the adhesive composition P is such that the aziridyl group of the aziridine crosslinking agent (D) is the amount of the carboxyl group of the (meth) acrylic acid ester polymer (A). , 0.001 to 0.1 molar equivalent, and preferably 0.003 to 0.02 molar equivalent.

  The adhesive composition P preferably further contains a silane coupling agent (E). When this silane coupling agent (E) 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 carboxyl group as a reactive functional group, the organic reactive group of the silane coupling agent (E) and the (meth) acrylic acid ester polymer (A) On the other hand, the alkoxysilyl group of the silane coupling agent (E) 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. In addition, when the reactive functional group of a polymer (A) is other than a carboxyl group, the silane coupling agent (E) which has the organic reactive group which acts with the said reactive functional group is selected suitably.

  The silane coupling agent (E) 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 transmittance, for example, substantially transparent Are suitable. It is preferable that the compounding quantity of such a silane coupling agent (E) is 0.01-1.0 mass part with respect to 100 mass parts of (meth) acrylic acid ester polymer (A), and is especially 0.1. It is preferable that it is 05-0.5 mass part.

  Specific examples of the silane coupling agent (E) include polymerizable unsaturated group-containing silicon compounds such as vinyltrimethoxysilane, vinyltriethoxysilane, (meth) acryloxypropyltrimethoxysilane, and 3-glycidoxypropyltri Silicon compounds having an epoxy structure such as methoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-aminopropyltrimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane And amino group-containing silicon compounds such as N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, and 3-isocyanatopropyltriethoxysilane. These may be used individually by 1 type and may be used in combination of 2 or more type.

  If desired, the adhesive composition P may be various additives commonly used in acrylic adhesives such as tackifiers, antistatic agents, antioxidants, ultraviolet absorbers, light stabilizers, softeners, Fillers and the like can be added.

[Method for producing adhesive composition]
The pressure-sensitive adhesive composition P is prepared by manufacturing each of the (meth) acrylic acid ester polymer (A) and the reactive (meth) acrylic acid ester polymer (B), mixing them, and if desired, any It can manufacture by adding a photoinitiator (C), an aziridine type crosslinking agent (D), a silane coupling agent (E), etc. in a step.

  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.

  On the other hand, the reactive (meth) acrylic acid ester polymer (B) is produced by reacting the (meth) acrylic acid ester polymer (b1) with the polymerizable double bond-containing compound (b2) as described above. can do. The (meth) acrylic acid ester polymer (b1) can be produced in the same manner as in the production method of the (meth) acrylic acid ester polymer (A).

  When the (meth) acrylic acid ester polymer (A) and the reactive (meth) acrylic acid ester polymer (B) are obtained, the solutions of the polymers (A) and (B) are mixed and a diluting solvent is added. Thereafter, if desired, a photopolymerization initiator (C), an aziridine-based cross-linking agent (D), a silane coupling agent (E), etc. are added and mixed thoroughly to obtain a pressure-sensitive adhesive composition diluted with a solvent ( A coating solution is obtained.

  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. In the case where the (meth) acrylic acid ester polymer (A) has a functional group (particularly a carboxyl group) and the adhesive composition P contains an aziridine-based crosslinking agent (D), the above heat treatment is performed. The (meth) acrylic acid ester polymer (A) is crosslinked.

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, a plurality of reactive (meth) acrylate polymers (B) are bonded to each other by cleavage of a polymerizable double bond in a side chain to form a three-dimensional network structure. It is presumed that the (meth) acrylic acid ester polymer (A) is inserted into the three-dimensional network structure and the structure X is formed. 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. Moreover, it is thought that the adhesive which concerns on this embodiment exhibits the outstanding uneven | corrugated followability and durability by said structure X. FIG. By being excellent in durability in this way, for example, even when kept at a high temperature of 80 ° C. or a high temperature and high humidity of 60 ° C./90% RH for 200 hours, it is prevented / suppressed from generating bubbles, peeling, bubbles, etc. Is done.

  In addition, when the (meth) acrylic acid ester polymer (A) has already been crosslinked by the aziridine-based crosslinking agent (D), the three-dimensional network structure of the reactive (meth) acrylic acid ester polymer (B) is: It is presumed that the polymer (A) is formed while being entangled with the crosslinked structure of the polymer (A) so that the polymer (A) is taken into the three-dimensional network structure.

In the pressure-sensitive adhesive according to this embodiment, the gel fraction immediately after formation of the pressure-sensitive adhesive layer is G1, and the gel fraction after storage for 7 days in an environment of 23 ° C. and 50% RH from the formation of the pressure-sensitive adhesive layer is G2. Sometimes the following formula Gel fraction variation rate (%) = | (G2-G1) / G2 | × 100
It is preferable that the variation rate of the gel fraction calculated from is within 3%. The measuring method of a gel fraction is as showing to the test example mentioned later. As described above, the gel fraction fluctuation rate of 3% or less indicates that the curing of the pressure-sensitive adhesive is substantially completed immediately after the pressure-sensitive adhesive layer is formed.

  Here, the term “immediately after the formation of the pressure-sensitive adhesive layer” refers to the first stage in which no additional artificial treatment is performed until the time of use after the formation of the pressure-sensitive adhesive layer. For example, in the case of an active energy ray-curable adhesive, it means immediately after irradiation with active energy rays. In actual measurement, due to the fact that it takes a certain amount of time from sample preparation to the start of various measurements, immediately after the formation of the pressure-sensitive adhesive layer is about a half day from the state in which the above-mentioned artificial treatment is no longer performed. To do.

  The gel fraction G1 immediately after forming the pressure-sensitive adhesive layer and the gel fraction G2 after storage for 7 days are each preferably 30 to 85%, particularly preferably 60 to 79%. When the gel fraction is less than 30%, the cohesive force of the pressure-sensitive adhesive is insufficient, and the durability may be lowered. Moreover, when the gel fraction exceeds 85%, the unevenness followability of the pressure-sensitive adhesive may deteriorate.

  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. 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, it is preferable that the adhesive force of the adhesive which concerns on this embodiment is 0.1-50 N / 25mm in the adhesive force with respect to an alkali free glass in any case immediately after adhesive layer formation and after storage for 7 days. In particular, 0.5 to 30 N / 25 mm is preferable. When the adhesive force is within the above range, it is possible to prevent floating or peeling when applied to an optical member such as a polarizing plate.

  The haze value (value measured according to JIS K7105) of the pressure-sensitive adhesive according to this embodiment is preferably 2.0% or less, particularly preferably 1.0% or less, and further 0.7. % 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. For example, an adhesive between optical members such as a polarizing plate (polarizing film) and a retardation plate (retarding film), or 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 a PSA layer, it is preferably 10 to 50 μm, particularly preferably 10 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 desired optical members, woven or non-woven fabrics using fibers such as rayon, acrylic, polyester, etc .; papers such as fine paper, glassine paper, impregnated paper, coated paper; metal foils such as aluminum and copper; synthesis Paper: Foam such as urethane foam, 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.

  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.

  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. The release sheet is preferably active energy ray permeable.

  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 obtain a coating film of the pressure-sensitive adhesive composition. The base material 13 is laminated on the exposed surface side of the coating film. Next, the adhesive layer 11 is formed by irradiating active energy rays through the release sheet 12. At this time, aging is unnecessary. The conditions for the active energy ray are as described above.

  Moreover, in order to manufacture the said adhesive sheet 1B, the coating solution of an adhesive composition is apply | coated to the peeling surface of one peeling sheet 12a (or 12b) by apply | coating the coating solution containing the said adhesive composition, and drying. The release sheet 12b is laminated on the exposed surface side of the coating film. Next, the adhesive layer 11 is formed by irradiating active energy rays from either side of the release 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 the base material 13 or the 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 13 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.

[Preparation Example]
1. Preparation of polymer (A1) In a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping device and a nitrogen introduction tube, 76 parts by mass of n-butyl acrylate, 20 parts by mass of methyl acrylate, 4 parts by mass of acrylic acid 200 parts by mass of ethyl acetate and 0.08 part by mass of 2,2′-azobisisobutyronitrile were charged, and 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 the method described later, and production of a polymer (A1) having a weight average molecular weight of 800,000 was confirmed.

2. Preparation of polymer (A2) In a reaction vessel equipped with a stirrer, thermometer, reflux condenser, dropping device and nitrogen introduction tube, 77 parts by mass of n-butyl acrylate, 20 parts by mass of methoxyethyl acrylate, 3 parts by mass of acrylic acid Part, 200 parts by mass of ethyl acetate, and 0.08 part by mass of 2,2′-azobisisobutyronitrile were charged, and 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, a molecular weight of a part of the obtained solution was measured by a method described later, and production of a polymer (A2) having a weight average molecular weight of 820,000 was confirmed.

3. Preparation of polymer (A3) In a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping device and a nitrogen introduction tube, 96 parts by mass of n-butyl acrylate, 4 parts by mass of acrylic acid, 200 parts by mass of ethyl acetate, Then, 0.03 part by mass of 2,2′-azobisisobutyronitrile was charged, and 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, molecular weight of a part of the obtained solution was measured by a method described later, and production of a polymer (A3) having a weight average molecular weight of 1.3 million was confirmed.

4). Preparation of polymer (B1) In a reaction vessel equipped with a stirrer, thermometer, reflux condenser, dropping device and nitrogen introduction tube, 85 parts by mass of n-butyl acrylate, 15 parts by mass of 2-hydroxyethyl acrylate (HEA) 200 parts by mass of ethyl acetate, 0.16 parts by mass of 2,2′-azobisisobutyronitrile, and 0.3 parts by mass of 2-mercaptoethanol were charged, and the air in the reaction vessel was replaced with nitrogen gas. While stirring in this nitrogen atmosphere, the reaction solution was heated to 70 ° C., reacted for 6 hours, cooled to room temperature, and a (meth) acrylic acid ester polymer having a hydroxyl group as the functional group (x) ( b1) was obtained.

  Next, methacryloyloxyethyl isocyanate (MOI) as the polymerizable double bond-containing compound (b2) is used so that the amount of isocyanate group of the MOI is 0 with respect to the hydroxyl group of HEA of the (meth) acrylic acid ester polymer (b1). Then, dibutyltin dilaurate was added as a catalyst and stirred at room temperature (23 ° C.) and normal pressure for 24 hours. Here, a molecular weight of a part of the obtained solution was measured by a method described later, and production of a polymer (B1) having a weight average molecular weight of 50,000 was confirmed.

5. Preparation of Polymer (B2) A methacryloyloxyethyl isocyanate (MOI) as the polymerizable double bond-containing compound (b2) is used in which the amount of isocyanate group of the MOI is that of HEA of the (meth) acrylic acid ester polymer (b1). The polymer (B1) except that the (meth) acrylic acid ester polymer (b1) and the polymerizable double bond-containing compound (b2) were reacted so as to be 0.2 molar equivalents relative to the hydroxyl group. Similarly, a polymer (B2) was produced. Part of the resulting solution was measured for molecular weight by the method described later, and production of a polymer (B2) having a weight average molecular weight of 50,000 was confirmed.

6). Preparation of Polymer (B3) 2-Methacryloyloxyethyl isocyanate (MOI) as the polymerizable double bond-containing compound (b2) is prepared from the (meth) acrylic acid ester polymer (b1) in which the amount of isocyanate group of the MOI is The polymer (B1) except that the (meth) acrylic acid ester polymer (b1) and the polymerizable double bond-containing compound (b2) were reacted so as to be 0.3 molar equivalents relative to the hydroxyl group of HEA. ) To produce a polymer (B3). Part of the obtained solution was measured for molecular weight by the method described later, and production of a polymer (B3) having a weight average molecular weight of 50,000 was confirmed.

7). Preparation of polymer (B4) In a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping device and a nitrogen introduction tube, 80 parts by mass of n-butyl acrylate and 20 parts by mass of 2-hydroxyethyl acrylate (HEA) 200 parts by mass of ethyl acetate, 0.10 parts by mass of 2,2′-azobisisobutyronitrile, and 0.3 parts by mass of 2-mercaptoethanol were charged, and the air in the reaction vessel was replaced with nitrogen gas. While stirring in this nitrogen atmosphere, the reaction solution was heated to 70 ° C., reacted for 6 hours, cooled to room temperature, and a (meth) acrylic acid ester polymer having a hydroxyl group as the functional group (x) ( b1) was obtained.

  As the polymerizable double bond-containing compound (b2), 2-methacryloyloxyethyl isocyanate (MOI) is used in which the amount of the isocyanate group of the MOI is 0 with respect to the hydroxyl group of HEA of the (meth) acrylate polymer (b1). In the same manner as in the polymer (B1) except that the (meth) acrylic acid ester polymer (b1) and the polymerizable double bond-containing compound (b2) were reacted so as to be 9 molar equivalents. A coalescence (B4) was produced. A part of the obtained solution was measured for molecular weight by the method described later, and production of a polymer (B4) having a weight average molecular weight of 300,000 was confirmed.

[Example 1]
After mixing 100 parts by mass (converted value of solid content) of the polymer (A1) obtained in the above preparation example and 20 parts by mass (converted value of solid content) of the polymer (B1), a photopolymerization initiator (C). Benzophenone and 1-hydroxycyclohexyl phenyl ketone mixed at a mass ratio of 1: 1 (Ciba Specialty Chemicals, Irgacure 500) 2 parts by weight (polymer (B1) 100 parts by weight) Agent (C) in an amount corresponding to 10 parts by mass), 0.05 part by mass of trimethylolpropane-tri-β-aziridinylpropionate as the aziridine-based crosslinking agent (D), and silane coupling agent (E) By adding 0.3 part by mass of 3-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name “KBM403”) and stirring sufficiently To give a dilute solution of the adhesive composition.

  The diluted solution of the obtained adhesive composition was applied to the release treatment surface of a release sheet (SP-PET3811, thickness: 38 μm, manufactured by Lintec Co., Ltd.) on one side of the polyethylene terephthalate film with a silicone release agent using a knife coater. It was applied and heat-treated at 90 ° C. for 1 minute to obtain a coating film of an adhesive composition.

Next, a polarizing plate composed of a polarizing film with a discotic liquid crystal layer, in which the polarizing film and the viewing angle widening film are integrated, is so that the exposed surface of the coating film of the adhesive composition and the surface of the discotic liquid crystal layer are in contact with each other. And pasted with the coating film of the above-mentioned adhesive composition. 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 coating film of an adhesive composition into an adhesive layer. The pressure-sensitive adhesive layer had a thickness of 25 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 22, Comparative Example 2]
Except for changing the types and blending amounts of the polymer (A), the polymer (B), the photopolymerization initiator (C) and the aziridine-based crosslinking agent (D) as shown in Table 1, the same manner as in Example 1 was performed. A polarizing plate with an adhesive layer was produced. The unit of numerical values shown in Table 1 is part by mass.

[Comparative Example 1]
Tolylene diisocyanate (TDI) adduct of trimethylolpropane as an isocyanate-based crosslinking agent (Coronate L, manufactured by Nippon Polyurethane Co., Ltd.) was added to 100 parts by mass (solid value converted value) of the polymer (A1) obtained in the above preparation example. 2.5 parts by mass and 0.3 part by mass of 3-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name “KBM403”) as a silane coupling agent (E) are added and sufficiently stirred. As a result, a diluted solution of the adhesive composition was obtained. A polarizing plate with a pressure-sensitive adhesive layer was produced in the same manner as in Example 1, using the obtained diluted solution of the pressure-sensitive adhesive composition.

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) In the same manner as in Examples or Comparative Examples, a pressure-sensitive adhesive sheet composed of a release sheet / pressure-sensitive adhesive layer (thickness 25 μm) / release sheet corresponding to each example was prepared.

  Immediately after production (within half a day), the pressure-sensitive adhesive sheet prepared as described above was sampled to a size of 80 mm × 80 mm, and only the pressure-sensitive adhesive layer was wrapped in a polyester mesh (mesh size 200). The mass 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. In addition, after the ultraviolet-ray was irradiated to the coating film of the adhesive composition and the adhesive layer was formed, the time required for sampling and immersing in ethyl acetate was about a half day. 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 haze value)
As a measurement sample, an adhesive sheet (stored for 7 days) similar to the adhesive sheet used for measurement of the gel fraction was prepared. About the adhesive layer of the said adhesive sheet, haze value (%) was measured according to JISK7105 using the haze meter (the Nippon Denshoku Industries Co., Ltd. make, NDH2000). The results are shown in Table 2.

[Test Example 3] (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. 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) and from the production of the polarizing plate with the pressure-sensitive adhesive layer (formation of the pressure-sensitive adhesive layer) for 7 days in an environment of 23 ° C. and 50% RH The one after storage 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 4] (Durability evaluation)
The pressure-sensitive adhesive layer-attached polarizing plate obtained in Examples or Comparative Examples was adjusted to a size of 233 mm × 309 mm using a cutting device (Super cutter manufactured by Hadano Seisakusho, PN1-600). The release sheet was peeled off and attached to non-alkali glass (Corning, EAGLEXG) through the exposed adhesive layer, and then pressurized at 0.5 MPa and 50 ° C. for 20 minutes in an autoclave manufactured by Kurihara Seisakusho.

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 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 in 4 sides. Δ: 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. in parts of less than 0.0 mm ×: parts of 1.0 mm or more from the outer peripheral edge on at least one of the four sides In addition, there are abnormal appearance defects of adhesives of 0.1 mm or more such as floating, peeling, foaming, streaks <durability conditions>
・ 80 ℃ dry
・ 60 ℃, relative humidity 90% RH

[Test Example 5] (Concavity and convexity followability test)
The adhesive composition prepared in Example or Comparative Example was applied to one side of a 100 μm thick polyethylene terephthalate (PET) film so that the coating thickness after drying was 50 μm, and heat-treated at 90 ° C. for 1 minute (drying Treatment) to obtain a coating film of the pressure-sensitive adhesive composition, followed by irradiation with ultraviolet rays under the following conditions to form a pressure-sensitive adhesive layer, thereby preparing a sample.
<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.

As shown in FIG. 3 and FIG. 4, a PET film having a size of 25 mm × 25 mm and a thickness of 25 μm is placed on a PMMA plate having a size of 125 mm × 125 mm and a thickness of 1.1 mm (manufactured by Mitsubishi Rayon Co., Ltd., Acrylite L001 transparent). The sample was attached to a PMMA plate so that the pressure-sensitive adhesive surface of the sample sealed a PET film having a thickness of 50 μm. Subsequently, it pressurized for 20 minutes at 0.5 MPa and 50 degreeC with the autoclave by Kurihara Seisakusho. And the length L of the pressure-sensitive adhesive layer floating generated in the vicinity of the edge of the sealed PET film (from the edge of the PET film having a thickness of 25 μm, the pressure-sensitive adhesive layer and the alkali-free glass plate The distance to the bonded part was arbitrarily measured at five points, and the average of them was measured. The evaluation criteria are as follows. The results are shown in Table 2.
A: Floating length L is less than 0.1 B: Floating length L is 0.1 or more and less than 0.5 mm B: Floating length L is 0.5 or more and less than 1.0 mm X: Floating length L is 1.0mm or more

  As is apparent from Table 2, the pressure-sensitive adhesive of the pressure-sensitive adhesive layer obtained in the Examples has a slight variation in gel fraction and pressure-sensitive adhesive force immediately after formation of the pressure-sensitive adhesive layer and after storage for 7 days. Excellent trackability and durability.

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

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

Claims (13)

(Meth) acrylic acid ester polymer (A) having a weight average molecular weight of 300,000 to 2,000,000,
A pressure-sensitive adhesive composition containing a reactive (meth) acrylic acid ester polymer (B) having a weight average molecular weight of 10,000 to 100,000 and having a polymerizable double bond in a side chain,
The ratio of the reactive (meth) acrylic acid ester polymer (B) to 100 parts by mass of the (meth) acrylic acid ester polymer (A) is 5 to 50 parts by mass,
The reactive (meth) acrylic acid ester polymer (B) contains 5-30% by mass of a functional group (x) -containing monomer as a constituent monomer unit, and the functional group It is obtained by reacting a polymerizable double bond-containing compound (b2) having a substituent (y) that reacts with the group (x),
The adhesive composition, wherein a molar equivalent of the substituent (y) to the functional group (x) is 0.1 to 0.6.   The said adhesive composition contains a photoinitiator (C) further, The adhesive composition of Claim 1 characterized by the above-mentioned.   The content of the photopolymerization initiator (C) is 5 to 30 parts by mass with respect to 100 parts by mass of the reactive (meth) acrylic acid ester polymer (B). The adhesive composition as described. The adhesive composition further contains an aziridine-based crosslinking agent (D),
The (meth) acrylic acid ester polymer (A) contains a functional group-containing monomer having a functional group capable of reacting with the aziridinyl group of the aziridine-based crosslinking agent (D) as a monomer unit constituting the polymer. The pressure-sensitive adhesive composition according to any one of claims 1 to 3, wherein:   The pressure-sensitive adhesive composition according to claim 4, wherein the functional group is a carboxyl group.   The content of the aziridine crosslinking agent (D) is such that the aziridinyl group of the aziridine crosslinking agent (D) is 0.001 to 0.001 with respect to the functional group in the (meth) acrylic acid ester polymer (A). The pressure-sensitive adhesive composition according to claim 4 or 5, wherein the pressure-sensitive adhesive composition is in an amount of 1 molar equivalent.   Furthermore, a silane coupling agent (E) is contained, The adhesive composition as described in any one of Claims 1-6 characterized by the above-mentioned.   The content of the silane coupling agent (E) is 0.01 to 1.0 part by mass with respect to 100 parts by mass of the (meth) acrylic acid ester polymer (A). 8. The adhesive composition according to 7.   The adhesive which hardens the adhesive composition as described in any one of Claims 1-8 by irradiation of an active energy ray. The pressure-sensitive adhesive according to claim 9, wherein an irradiation amount of the active energy ray is 50 to 1000 mJ / cm ² . A pressure-sensitive adhesive sheet comprising a base material and a pressure-sensitive adhesive layer,
The said adhesive layer consists of an adhesive of Claim 9 or 10, The adhesive sheet characterized by the above-mentioned.   The pressure-sensitive adhesive sheet according to claim 11, wherein the base material is an optical member. Two release sheets,
An adhesive sheet comprising 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 9 or 10, The adhesive sheet characterized by the above-mentioned.

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