JP2013056962A - 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, excellent in both of light leakage resistance and durability and having a low haze value when applied to optical members such as a polarizing plate.SOLUTION: The pressure-sensitive adhesive composition 11 includes a first (meth)acrylic ester polymer (A) having 500,000-2,500,000 weight-average molecular weight and containing substantially no carboxy group, a second (meth)acrylic ester polymer (B) having 50,000-2,500,000 weight-average molecular weight and containing 1-20 mass% monomer having a carboxy group as a monomer unit composing the polymer, and a polyrotaxane compound (C) having a cyclic oligosaccharide as a cyclic molecule, wherein the content of the second (meth)acrylic ester polymer (B) to 100 pts.mass first (meth)acrylic ester polymer (A) is 0.1-30 pts.mass and the content of the polyrotaxane compound (C) in the pressure-sensitive adhesive composition is 0.1-5.0 mass%.

Description

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

  In general, in a liquid crystal panel, a pressure-sensitive adhesive layer formed from a pressure-sensitive adhesive composition is often used to bond a polarizing plate or a retardation plate to a glass substrate of a liquid crystal cell. However, since optical members such as polarizing plates and retardation plates are easily shrunk by heat, etc., shrinkage occurs due to heat history, and as a result, the adhesive layer laminated on the optical member cannot follow the shrinkage. Problems have been pointed out, such as peeling at the interface (so-called floating or peeling), or light leakage (so-called white spots) due to displacement of the optical axis of the optical member due to stress during contraction of the optical member. .

  As a method for preventing this, (1) a method of suppressing the contraction of the optical member itself by bonding a pressure-sensitive adhesive layer having high adhesive strength and excellent shape stability to an optical member such as a polarizing plate. Or (2) a method using a pressure-sensitive adhesive layer having a small stress when the optical member is contracted. As the method (1), it is effective to use a pressure-sensitive adhesive layer having a high storage elastic modulus as disclosed in Patent Document 1. On the other hand, as the method (2), it is effective to use a pressure-sensitive adhesive layer having excellent stress relaxation properties that can flexibly cope with deformation of the optical member. However, conventionally, when it was attempted to form such an adhesive layer having excellent stress relaxation properties, it was necessary to design a low crosslinking density in the adhesive layer. If it does so, there existed a problem that the intensity | strength of adhesive layer itself fell and durability deteriorated.

  Therefore, in Patent Documents 2 to 4, by adding a plasticizer, liquid paraffin, urethane elastomer or the like to the acrylic pressure-sensitive adhesive instead of lowering the cross-linking density of the pressure-sensitive adhesive layer, the resulting pressure-sensitive adhesive composition becomes moderately soft. Thus, stress relaxation properties are imparted to the pressure-sensitive adhesive layer, thereby obtaining light leakage resistance and durability.

  However, the pressure-sensitive adhesive composition to which a plasticizer or liquid paraffin is added has a drawback that the formed pressure-sensitive adhesive layer bleeds out the plasticizer and liquid paraffin over time. As a result, various problems such as a decrease in adhesion durability and contamination of the liquid crystal cell as an adherend have been a concern. Moreover, the upper limit of the addition amount of a urethane elastomer will be restrict | limited if the adhesive composition which added the urethane elastomer maintains compatibility. For this reason, in the adhesive layer obtained from this adhesive composition, the tendency for the improvement of stress relaxation property to be insufficient was seen. Furthermore, when the addition amount of the urethane elastomer is increased in order to improve the stress relaxation property, the compatibility with the acrylic pressure-sensitive adhesive is lowered, and problems such as cloudiness have occurred. Thus, it has been difficult for the conventional techniques to fundamentally improve the light leakage resistance and durability of the pressure-sensitive adhesive layer formed from the pressure-sensitive adhesive composition for optical members.

  On the other hand, Patent Documents 5 to 7 propose a pressure-sensitive adhesive composition in which a polyrotaxane having cyclodextrin is blended with a pressure-sensitive adhesive mainly composed of an acrylate copolymer. Thus, when a polyrotaxane is introduced into the pressure-sensitive adhesive composition, mechanical bonds that are neither covalent bonds nor non-covalent bonds are incorporated into the pressure-sensitive adhesive system, which is difficult in the conventional method (2). Both light leakage resistance and durability can be realized.

JP 2006-235568 A Japanese Patent Laid-Open No. 5-45517 Japanese Patent Laid-Open No. 9-137143 JP 2005-194366 A JP 2007-224133 A JP 2010-138258 A JP 2010-138259 A

  However, the acrylic acid ester copolymer, which is the main component of the pressure-sensitive adhesive, and the polyrotaxane having cyclodextrin are poorly compatible, and even when a small amount of the polyrotaxane is added, the resulting pressure-sensitive adhesive composition becomes cloudy and has a haze value. However, the pressure-sensitive adhesive compositions described in Patent Documents 5 to 7 sometimes have insufficient optical properties.

  The present invention has been made in view of such a situation, and when applied to an optical member such as a polarizing plate, the adhesive composition is excellent in both light leakage resistance and durability, and has a low haze value, It aims at providing an adhesive and an adhesive sheet.

  In order to achieve the above object, first, the present invention includes a first (meth) acrylic acid ester polymer (A) having substantially no carboxyl group and having a weight average molecular weight of 500,000 to 2.5 million, A second (meth) acrylic acid ester polymer (B) having a weight average molecular weight of 50,000 to 2,500,000 containing 1 to 20% by mass of a monomer having a carboxyl group as a monomer unit constituting the polymer; A pressure-sensitive adhesive composition containing a polyrotaxane compound (C) having a cyclic oligosaccharide as a molecule, wherein the second (meth) relative to 100 parts by mass of the first (meth) acrylic acid ester polymer (A) The ratio of the acrylic ester polymer (B) is 0.1 to 30 parts by mass, and the content of the polyrotaxane compound (C) in the adhesive composition is 0.1 to 5.0% by mass. Providing an adhesive composition, characterized in that there (invention 1).

  The pressure-sensitive adhesive composition according to the above invention (Invention 1) contains a polyrotaxane compound, and exhibits high stress relaxation properties when a pressure-sensitive adhesive is formed by mechanical bonding of the polyrotaxane compound. Moreover, in the said adhesive composition, the compatibility of an adhesive component and a polyrotaxane improves by blending the (meth) acrylic acid ester polymer containing a carboxyl group, and a haze value becomes low. According to such an adhesive composition, when applied to an optical member such as a polarizing plate, an adhesive and an adhesive sheet having both excellent light leakage resistance and durability due to high stress relaxation properties and a low haze value can be obtained. .

  In the said invention (invention 1), it is preferable to further contain a crosslinking agent (D) (invention 2).

  In the said invention (invention 2), it is preferable that said 1st (meth) acrylic acid ester polymer (A) has a reactive group which can react with the reactive group which the said crosslinking agent (D) has (invention). 3).

  In the said invention (invention 2 and 3), it is preferable that the cyclic molecule of the said polyrotaxane compound (C) has a reactive group which can react with the reactive group which the said crosslinking agent (D) has (invention 4).

  In the said invention (invention 2-4), the said 1st (meth) acrylic acid ester polymer (A) contains the monomer which has a hydroxyl group which is a reactive group as a monomer unit which comprises the said polymer, The cyclic molecule of the polyrotaxane compound (C) preferably has a hydroxyl group as a reactive group, and the crosslinking agent (D) preferably has an isocyanate group as a reactive group (Invention 5).

  In the said invention (invention 1-5), it is preferable to further contain a silane coupling agent (E) (invention 6).

  2ndly this invention provides the adhesive formed by bridge | crosslinking the said adhesive composition (invention 1-6) (invention 7).

  Thirdly, the present invention provides a pressure-sensitive adhesive sheet comprising a substrate and a pressure-sensitive adhesive layer, wherein the pressure-sensitive adhesive layer comprises the pressure-sensitive adhesive (invention 7) ( Invention 8).

  In the said invention (invention 8), it is preferable that the said base material is an optical member (invention 9).

  In the said invention (invention 9), it is preferable that the said optical member is a polarizing plate or a phase difference plate (invention 10).

  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. The pressure-sensitive adhesive sheet is characterized in that the layer is composed of the pressure-sensitive adhesive (Invention 7) (Invention 11).

  In the present invention, by containing the polyrotaxane compound, high stress relaxation is exhibited by the mechanical bond of the polyrotaxane compound. Further, by blending a (meth) acrylic acid ester polymer containing a carboxyl group, the compatibility between the adhesive component and the polyrotaxane is improved, and the haze value is lowered. That is, according to the present invention, when applied to an optical member such as a polarizing plate, it is excellent in both light leakage resistance and durability due to high stress relaxation properties, and has a low haze value. A sheet is obtained.

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. It is a figure which shows the measurement area | region of the light leak test in a polarizing plate with an adhesive layer.

Hereinafter, embodiments of the present invention will be described.
[Adhesive composition]
The pressure-sensitive adhesive composition according to this embodiment includes a first (meth) acrylic acid ester polymer (A) (main polymer) substantially free of carboxyl groups and having a weight average molecular weight (Mw) of 500,000 to 2.5 million. And a second monomer having a weight average molecular weight (Mw) of 50,000 to 2.5 million, containing 1 to 20% by mass of a monomer having a carboxyl group (carboxyl group-containing monomer) as a monomer unit constituting the polymer. (Meth) acrylic acid ester polymer (B) (corresponding to blend polymer) and polyrotaxane compound (C) having a cyclic oligosaccharide as a cyclic molecule, preferably further containing a crosslinking agent (D), Preferably it further contains a silane coupling agent (E). In addition, in this specification, (meth) acrylic acid ester means both acrylic acid ester and methacrylic acid ester. The same applies to other similar terms. Further, the “polymer” includes the concept of “copolymer”.

  In the pressure-sensitive adhesive composition according to this embodiment, the first (meth) acrylic acid ester polymer (A) that is the main polymer does not substantially contain a carboxyl group, so that the first (meth) acrylic acid ester Since the higher order structure described later can be formed without increasing the reactivity of the polymer (A), the durability of the resulting pressure-sensitive adhesive can be improved.

  Here, “substantially does not contain a carboxyl group” means that it does not contain a carboxyl group at all and also contains a trace amount that does not adversely affect the durability of the pressure-sensitive adhesive. Specifically, the content of the carboxyl group-containing monomer as the constituent unit of the first (meth) acrylic acid ester polymer (A) is preferably less than 0.1% by mass, particularly preferably 0.05. It is less than mass%.

  When the pressure-sensitive adhesive composition according to this embodiment contains a crosslinking agent (D), the first (meth) acrylic acid ester polymer (A) has a reactive group (d) and a crosslinking agent (D). It preferably has a reactive group (a) capable of reacting. The reactive group (d) which can react with the reactive group (d) of the crosslinking agent (D) acts with the crosslinking agent (D) to form a chemical bond such as a covalent bond or an ionic bond. A functional group that can be used. When the first (meth) acrylic acid ester polymer (A) has the reactive group (a) as described above, the polymer (A) can be crosslinked by the crosslinking agent (D). Thereby, the polymer (A) is bonded to one cyclic molecule of the polyrotaxane compound (C) via the crosslinking agent (D) by the reactive group (a), and similarly, another polymer (A) is bonded to the polymer (A). It is presumed to bind to another cyclic molecule of the polyrotaxane compound (C). As a result, the plurality of polymers (A) are presumed to form higher-order structures such as a three-dimensional network structure that are mechanically bonded to each other by the polyrotaxane compound (C). With such a higher-order structure, the resulting pressure-sensitive adhesive exhibits excellent light leakage resistance and durability. In addition, it is not necessary that all of the obtained pressure-sensitive adhesive has the above-mentioned estimated structure, and the structure in which the two polymers (A) are directly bonded by the crosslinking agent (B) without the polyrotaxane compound (C), etc. May be included.

  The reactive group (a) capable of reacting with the reactive group (d) of the crosslinking agent (D) is particularly preferably a reactive group having a higher reactivity with the crosslinking agent (D) than with the carboxyl group. As a result, the first (meth) acrylate polymer (A) is cross-linked while the carboxyl group of the second (meth) acrylate polymer (B) remains, and the above estimated structure is formed. be able to. For example, when the crosslinking agent (D) is an isocyanate-based crosslinking agent (the reactive group (d) is an isocyanate group), the reactive group (a) of the polymer (A) includes a hydroxyl group, a thiol group, an amino group, etc. Can be preferably mentioned. Among these, from the viewpoint of few side reactions and few problems such as odor, a hydroxyl group can be particularly preferably mentioned as the reactive group (a) of the polymer (A). That is, the polymer (A) is a monomer having a reactive group (a) capable of reacting with the reactive group (d) of the crosslinking agent (D) as a monomer unit constituting the polymer (reactive group ( a) containing monomer) is preferable, and a hydroxyl group-containing monomer is particularly preferable.

  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.

  Moreover, in order to express adhesiveness, a 1st (meth) acrylic acid ester polymer (A) is a (meth) acrylic acid whose carbon number of an alkyl group is 1-20 as a monomer unit which comprises the said polymer. It is preferable to contain an alkyl ester. 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, n-butyl (meth) acrylate or 2-ethylhexyl (meth) acrylate is preferable. In addition, these may be used independently and may be used in combination of 2 or more type.

  Furthermore, the first (meth) acrylic acid ester polymer (A) is not limited to the reactive group (a) -containing monomer and the (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group, As long as the effects of the present invention are not impaired, other monomers can be appropriately used as the structural unit.

  As said other monomer, the monomer which does not contain the functional group which has reactivity with a crosslinking agent (D) is mentioned preferably. Specifically, as the monomer, (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, Non-crosslinkable acrylamide such as acrylamide and methacrylamide, non-crosslinkable tertiary amino groups such as N, N-dimethylaminoethyl (meth) acrylate and N, N-dimethylaminopropyl (meth) acrylate ( (Meth) acrylic acid ester, vinyl acetate, styrene, etc. are mentioned. These may be used alone or in combination of two or more.

  The first (meth) acrylic acid ester polymer (A) preferably contains 0.2 to 40% by mass of the reactive group (a) -containing monomer as a monomer unit constituting the polymer. In particular, the content is preferably 0.5 to 20% by mass, and more preferably 0.8 to 10% by mass. By containing the reactive group (a) -containing monomer in the above range, the degree of crosslinking of the first (meth) acrylic acid ester polymer (A) becomes preferable, and in combination with the polyrotaxane compound (C), The stress relaxation property of the pressure-sensitive adhesive can be improved more effectively. When the content of the reactive group (a) -containing monomer is less than 0.2% by mass, the first (meth) acrylic acid ester polymer (A) is not sufficiently cross-linked, which may reduce durability. is there. On the other hand, when the content of the reactive group (a) -containing monomer exceeds 40% by mass, the first (meth) acrylic acid ester polymer (A) is excessively cross-linked and the stress relaxation property may be lowered. In addition, the residual reactive group (a) of the reactive group (a) -containing monomer after crosslinking may result in poor durability particularly under wet heat conditions. Moreover, the light leakage resistance of the adhesive sheet obtained becomes more excellent by making the upper limit of content of a reactive group (a) containing monomer into 10 mass%.

  In the first (meth) acrylic acid ester polymer (A), a (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group is used as a monomer unit constituting the polymer. It is preferably contained in an amount of 80% to 99.5% by mass, more preferably 85 to 99% by mass. When the content of the (meth) acrylic acid alkyl ester is less than 60% by mass, the adhesive strength may be too low. On the other hand, if the content of the (meth) acrylic acid alkyl ester exceeds 99.8% by mass, the proportion of the reactive group (a) -containing monomer may be insufficient.

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

  The weight average molecular weight of the first (meth) acrylic acid ester polymer (A) is 500,000 to 2,500,000, preferably 700,000 to 2,000,000, particularly preferably 900,000 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 first (meth) acrylic acid ester polymer (A) is less than 500,000, the resulting pressure-sensitive adhesive may be inferior in durability and reworkability. When the weight average molecular weight of the first (meth) acrylic acid ester polymer (A) exceeds 2.5 million, the second (meth) acrylic acid ester polymer (B), the polyrotaxane compound (C) and the like There is a possibility that the compatibility is deteriorated and the stress relaxation property of the obtained pressure-sensitive adhesive is lowered.

  In the pressure-sensitive adhesive composition according to this embodiment, the second (meth) acrylic acid ester polymer (B) which is a blend polymer contains a carboxyl group-containing monomer as a monomer unit constituting the polymer. That is, by containing a carboxyl group, the compatibility between the pressure-sensitive adhesive components (polymers (A) and (B)) and the polyrotaxane compound (C) is improved, and the haze value of the pressure-sensitive adhesive obtained is lowered.

  The second (meth) acrylic acid ester polymer (B) in the present embodiment is a (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group, a carboxyl group-containing monomer, and used as desired. It is preferably a copolymer with another monomer that does not contain a functional group having reactivity with the crosslinking agent (D).

  When the first (meth) acrylic acid ester polymer (A) has a reactive group (a) that is more reactive with the crosslinking agent (D) than the carboxyl group (for example, the crosslinking agent (D) In the case where is an isocyanate-based crosslinking agent, a hydroxyl group is applicable.), The second (meth) acrylic acid ester polymer (B) has a higher reactivity with the crosslinking agent (D) than the carboxyl group. It preferably has no group. Thereby, it is presumed that the polymer (A) and the polyrotaxane compound (C) can form a higher order structure controlled via the crosslinking agent (D). On the other hand, it is presumed that the polymer (B) is not linked to the higher order structure via a covalent bond or the like, or is linked to the higher order structure at a very small ratio. Thereby, since the polymer (B) exists in the above-mentioned higher order structure in a state with a large degree of freedom, the polarity difference between the polymer (A) and the polyrotaxane compound (C) is relaxed, and the compatibilization of both components is achieved. It is estimated that it can function effectively.

  As the (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms in the alkyl group and the other monomer, those described in the first (meth) acrylic acid ester polymer (A) should be used similarly. Can do.

  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.

  The second (meth) acrylic acid ester polymer (B) contains 1 to 20% by mass, preferably 1.5 to 15% by mass of a carboxyl group-containing monomer as a monomer unit constituting the polymer. Particularly preferably, the content is 2 to 10% by mass. By including the carboxyl group-containing monomer in such a range, an excellent effect of reducing the haze value of the pressure-sensitive adhesive can be obtained. That is, if the content of the carboxyl group-containing monomer in the second (meth) acrylic acid ester polymer (B) is less than 1% by mass, the above effect cannot be obtained. On the other hand, when the content of the carboxyl group-containing monomer exceeds 20% by mass, the adhesive strength of the resulting adhesive increases with time, or the first (meth) acrylic acid ester polymer (A) and the polyrotaxane compound ( The balance of reactivity between C) and the crosslinking agent (D) is lost, and an appropriate higher-order structure cannot be maintained, and the durability performance may be reduced.

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

  The weight average molecular weight of the second (meth) acrylic acid ester polymer (B) is 50,000 to 2,500,000, preferably 100,000 to 2,000,000, particularly preferably 300,000 to 1,500,000.

  When the weight average molecular weight of the second (meth) acrylic acid ester polymer (B) is less than 50,000, the polymer (B) bleeds out from the resulting pressure-sensitive adhesive, and the durability of the pressure-sensitive adhesive decreases. There is a risk. Moreover, when the weight average molecular weight of the second (meth) acrylic acid ester polymer (B) exceeds 2.5 million, the first (meth) acrylic acid ester polymer (A), the polyrotaxane compound (C) and the like There is a possibility that the compatibility is deteriorated and the stress relaxation property of the obtained pressure-sensitive adhesive is lowered.

  In the present embodiment, each of the first (meth) acrylic acid ester polymer (A) and the second (meth) acrylic acid ester polymer (B) may be used alone. Two or more kinds may be used in combination.

  The ratio of the second (meth) acrylic acid ester polymer (B) to 100 parts by mass of the first (meth) acrylic acid ester polymer (A) is 0.1 to 30 parts by mass, preferably 0.8. It is 5-20 mass parts, Most preferably, it is 1-15 mass parts. When the ratio of the second (meth) acrylic acid ester polymer (B) is less than 0.1 parts by mass, the effect of reducing the haze value of the pressure-sensitive adhesive cannot be obtained. On the other hand, if the proportion of the second (meth) acrylic acid ester polymer (B) exceeds 30 parts by mass, the adhesive strength of the resulting adhesive may increase with time or the durability performance may decrease.

  The polyrotaxane compound (C) is a compound in which a linear molecule penetrates through openings of at least two cyclic molecules and has a blocking group at both ends of the linear molecule. In this polyrotaxane compound (C), the cyclic molecule can freely move on the linear molecule. The pressure-sensitive adhesive composition according to the present embodiment contains the polyrotaxane compound (C) having such a mechanical bond, so that the obtained pressure-sensitive adhesive exhibits high stress relaxation properties, light leakage resistance and durability. It will be excellent for both.

  The polyrotaxane compound (C) in the present embodiment has a cyclic oligosaccharide as a cyclic molecule. By using a cyclic oligosaccharide as the cyclic molecule of the polyrotaxane compound (C), it becomes possible to select an appropriate ring diameter, and thereby the effect due to the movement of the cyclic molecule on the linear molecule is easily exhibited. In addition, since the cyclic oligosaccharide has a hydroxyl group, the reaction with the polyisocyanate compound is easy when the crosslinking agent (D) is, for example, a polyisocyanate compound. Furthermore, introduction of various substituents and the like is easy, whereby the compatibility between the polyrotaxane compound (C) and other components can be adjusted by the polyrotaxane compound (C). Furthermore, if it is cyclic oligosaccharide, there also exists an advantage that acquisition is easy. In the present specification, “cyclic” of “cyclic molecule” or “cyclic oligosaccharide” means substantially “cyclic”. In other words, the cyclic molecule may not be completely closed as long as it can move on the linear molecule, and may have a helical structure, for example.

  Preferred cyclic oligosaccharides include cyclodextrins such as α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin, and among them, α-cyclodextrin is particularly preferable. Two or more kinds of cyclic molecules of the polyrotaxane compound (C) may be mixed in the polyrotaxane compound (C) or the pressure-sensitive adhesive composition.

  The cyclic molecule (cyclic oligosaccharide) of the polyrotaxane compound (C) preferably has a reactive group (c), particularly when the adhesive composition according to this embodiment contains a crosslinking agent (D). It preferably has a reactive group (c) capable of reacting with the reactive group (d) of the crosslinking agent (D). Examples of the reactive group (c) include a hydroxyl group, a carboxyl group, an amino group, and the like. One of these can be used alone, or two or more can be used in combination. In particular, when the crosslinking agent (D) is an isocyanate-based crosslinking agent, the reactive group (d) of the crosslinking agent (D) is an isocyanate group, in which case the cyclic molecule of the polyrotaxane compound (C) is reacted with It is preferable to have a hydroxyl group as the functional group (c).

  The pressure-sensitive adhesive composition according to this embodiment contains a crosslinking agent (D), the crosslinking agent (D), the first (meth) acrylic acid ester polymer (A), and the crosslinking agent (D). When the polyrotaxane compound (C) reacts and the first (meth) acrylate polymer (A) and the polyrotaxane compound (C) are crosslinked via the crosslinking agent (D), the polyrotaxane compound ( In C), the cyclic molecule freely moves on the linear molecule, so that the flexibility as a cross-linked product is remarkably improved. Thereby, the obtained adhesive exhibits a very high stress relaxation property, and becomes more excellent in light leakage resistance and durability.

  The content of the reactive group (c) in the cyclic molecule is preferably 4 to 90%, particularly preferably 20 to 70%. In addition, the content rate here is the case where the amount of a reactive group (for example, a hydroxyl group in cyclodextrin) that a cyclic molecule has conventionally is 100, and a part of the reactive group is made non-reactive by substitution or the like. Represents the amount of the remaining reactive group. If the content is less than 4%, the polyrotaxane compound (C) may not sufficiently react with other components (for example, the crosslinking agent (D)). On the other hand, if the content exceeds 90%, a large number of crosslinks occur in the same cyclic molecule, so that the cyclic molecule itself becomes a crosslink point, and the polyrotaxane compound (C) as a whole cannot exert the effect of the crosslink point. There is a possibility that sufficient stress relaxation property of the pressure-sensitive adhesive layer cannot be secured.

  The reactive group (c) may be present in the cyclic molecule via a substituent, and further, two or more different substituents are different via the reactive group (c) of the cyclic molecule. And any of the substituents may have a reactive group (c).

  Examples of the substituent include an acetyl group, an alkyl group, a trityl group, a tosyl group, a trimethylsilane group, and a phenyl group, as well as a polyester chain, an oxyethylene chain, an alkyl chain, an ether chain, an ester chain, and an acrylate chain. Etc. By having these substituents, the solubility of the polyrotaxane compound (C) can be improved. The number average molecular weight of the substituent is preferably 100 to 10,000, and particularly preferably 400 to 2,000. The introduction rate (substitution degree) of the substituent to the reactive group is preferably 10 to 90%, and particularly preferably 30 to 70%.

  The linear molecule of the polyrotaxane compound (C) is a molecule or substance that is included in a cyclic molecule and can be integrated by a mechanical bond rather than a chemical bond such as a covalent bond. If it is, it will not be specifically limited. In the present specification, “linear” of “linear molecule” means substantially “linear”. That is, the linear molecule may have a branched chain as long as the cyclic molecule can move on the linear molecule.

  As the linear molecule of the polyrotaxane compound (C), for example, polyethylene glycol, polypropylene glycol, polyisoprene, polyisobutylene, polybutadiene, polytetrahydrofuran, polyacrylate, polydimethylsiloxane, polyethylene, polypropylene and the like are preferable. Two or more kinds of linear molecules may be mixed in the pressure-sensitive adhesive composition.

  The number average molecular weight of the linear molecule of the polyrotaxane compound (C) is preferably 3,000 to 300,000, particularly preferably 10,000 to 200,000, and more preferably 20,000 to 100. 1,000 is preferred. When the number average molecular weight is less than 3,000, the amount of movement of the cyclic molecule on the linear molecule becomes small, and the stress relaxation property of the pressure-sensitive adhesive may not be sufficiently obtained. Moreover, when a number average molecular weight exceeds 300,000, there exists a possibility that the solubility to the solvent of a polyrotaxane compound (C) and compatibility with an adhesive component (polymer (A) and (B)) may worsen.

  The blocking group of the polyrotaxane compound (C) is not particularly limited as long as the cyclic molecule is a group capable of maintaining a form in which the cyclic molecule is skewered with a linear molecule. Examples of such groups include bulky groups and ionic groups.

  Specifically, the blocking group of the polyrotaxane compound (C) may be a dinitrophenyl group, a cyclodextrin, an adamantane group, a trityl group, a fluorescein, a pyrene, an anthracene, or the like, or a number average molecular weight of 1,000. A polymer main chain or side chain of ˜1,000,000 is preferable, and two or more of these blocking groups may be mixed in the polyrotaxane compound (C) or the pressure-sensitive adhesive composition.

  Examples of the polymer having a number average molecular weight of 1,000 to 1,000,000 include polyamide, polyimide, polyurethane, polydimethylsiloxane, and polyacrylate.

  The cyclic molecule is preferably 0.1 to 60%, particularly preferably when the amount of the cyclic molecule included in the skewered form by the linear molecule is 100%. Is skewered into linear molecules in an amount of 1-50%, more preferably 5-40%.

  The maximum inclusion amount of the cyclic molecule can be determined by the length of the linear molecule and the thickness of the cyclic molecule. For example, when the linear molecule is polyethylene glycol and the cyclic molecule is an α-cyclodextrin molecule, the maximum inclusion amount is experimentally determined (see Macromolecules 1993, 26, 5698-5703).

  The polyrotaxane compound (C) described above can be obtained by a conventionally known method (for example, a method described in JP-A-2005-154675).

  The content of the polyrotaxane compound (C) in the pressure-sensitive adhesive composition according to this embodiment is 0.1 to 5.0% by mass, preferably 0.2 to 4.0% by mass, and particularly 0. It is preferable that it is 3-3.0 mass%. When the content of the polyrotaxane compound (C) is less than 0.1% by mass, excellent stress relaxation properties, and hence excellent light leakage resistance and durability due to the polyrotaxane compound (C) cannot be obtained. On the other hand, when the content of the polyrotaxane compound (C) exceeds 5.0% by mass, the compatibility with the pressure-sensitive adhesive components (polymers (A) and (B)) is deteriorated, and the haze value of the obtained pressure-sensitive adhesive is increased. To do.

  The adhesive composition according to the present embodiment preferably further contains a crosslinking agent (D). When the first (meth) acrylic acid ester polymer (A) and the polyrotaxane compound (C) are cross-linked by the cross-linking agent (D), as described above, the resulting pressure-sensitive adhesive has a very high stress relaxation property. Demonstrates excellent light leakage resistance and durability.

  Examples of the crosslinking agent (D) include isocyanate crosslinking agents, epoxy crosslinking agents, aziridine crosslinking agents, metal chelate crosslinking agents, and the like. Among these, the first (meth) acrylic acid ester polymer (A) In addition, an isocyanate-based crosslinking agent that can easily form a crosslinked structure with the polyrotaxane compound (C) is preferable. That is, if the first (meth) acrylic acid ester polymer (A) contains a hydroxyl group as a reactive group and the cyclic molecule of the polyrotaxane compound (C) contains a hydroxyl group as a reactive group, the crosslinking agent (D ), It is possible to easily crosslink the first (meth) acrylic acid ester polymer (A) and the polyrotaxane compound (C) via the crosslinking agent (D). .

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

  Moreover, it is also preferable to use an epoxy crosslinking agent in combination with the isocyanate crosslinking agent. Examples of the epoxy-based crosslinking agent include 1,3-bis (N, N′-diglycidylaminomethyl) cyclohexane, N, N, N ′, N′-tetraglycidyl-m-xylenediamine, and ethylene glycol diglycidyl ether. 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidylaniline, diglycidylamine and the like.

  The said crosslinking agent (D) (isocyanate type crosslinking agent, epoxy type crosslinking agent) can be used individually by 1 type or in combination of 2 or more types.

  The content of the crosslinking agent (D) in the pressure-sensitive adhesive composition according to this embodiment is preferably 0.1 to 3.0% by mass, and particularly preferably 0.15 to 2.0% by mass. More preferably, it is 0.2 to 1.0% by mass. If the content of the cross-linking agent (D) is less than 0.1% by mass, the above-described cross-linking structure may not provide very excellent stress relaxation properties, and thus very good light leakage resistance and durability. . On the other hand, when the content of the crosslinking agent (D) exceeds 3.0% by mass, the degree of crosslinking becomes excessive, and the stress relaxation property of the obtained pressure-sensitive adhesive may be inhibited.

  The pressure-sensitive adhesive composition according to this embodiment preferably further contains a silane coupling agent (E). When this silane coupling agent (E) is contained, the alkoxysilyl group of the silane coupling agent (E) acts on the adherend surface such as a glass substrate, and thus, for example, when a polarizing plate is bonded to a liquid crystal glass cell or the like. In addition, the adhesion between the pressure-sensitive adhesive and the liquid crystal glass cell becomes better.

  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 A transparent one is preferred. The amount of the silane coupling agent (E) added is 100 parts by mass in total of the first (meth) acrylic acid ester polymer (A) and the second (meth) acrylic acid ester polymer (B). It is preferable that it is 0.01-0.5 mass part with respect to it, and it is especially preferable that it is 0.05-0.3 mass part.

  Specific examples of the silane coupling agent (E) 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- Examples include amino group-containing silicon compounds such as (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.

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

[Method for producing adhesive composition]
The said adhesive composition manufactures each of the 1st (meth) acrylic acid ester polymer (A) and the 2nd (meth) acrylic acid ester polymer (B), mixes them, and is arbitrary. It can be produced by adding a polyrotaxane compound (C) and, if desired, a crosslinking agent (D) and a silane coupling agent (E) at this stage.

  As a preferred specific example, the (meth) acrylic acid ester polymers (A) and (B) are separately produced by a normal radical polymerization method. The polymerization of the (meth) acrylic acid ester polymers (A) and (B) can be carried out 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.

  Next, the solutions of the obtained polymers (A) and (B) are mixed, and a diluting solvent is added. Thereafter, a polyrotaxane compound (C) and, if desired, a crosslinking agent (D) and a silane coupling agent (E) are added and mixed thoroughly to obtain an 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 is obtained by crosslinking the pressure-sensitive adhesive composition. Crosslinking of the pressure-sensitive adhesive composition can be performed by heat treatment. In addition, this heat processing can also serve as the drying process at the time of volatilizing the dilution solvent etc. of an adhesive composition.

  When performing heat processing, it is preferable that heating temperature is 50-150 degreeC, and it is especially preferable that it is 70-120 degreeC. The heating time is preferably 30 seconds to 3 minutes, particularly preferably 50 seconds to 2 minutes. Furthermore, it is particularly preferable to provide a curing period of about 1 to 2 weeks at room temperature (for example, 23 ° C., 50% RH) after the heat treatment.

  By the heat treatment (and curing), the pressure-sensitive adhesive composition is well crosslinked. In particular, when the adhesive composition contains a crosslinking agent (D), the first (meth) acrylic acid ester polymer (A), the polyrotaxane compound (C), and the like via the crosslinking agent (D). Are well cross-linked.

  The haze value of the pressure-sensitive adhesive according to this embodiment is preferably 8% or less, particularly preferably 5% or less, and further preferably 2.0% or less. In addition, the haze value here is a value measured using a haze meter (in the examples, NDH2000 manufactured by Nippon Denshoku Industries Co., Ltd.) according to JIS K7105.

  In the pressure-sensitive adhesive according to this embodiment, the second (meth) acrylic acid ester polymer (B) in the pressure-sensitive adhesive composition contains a carboxyl group, so that the pressure-sensitive adhesive components (polymer (A) and ( Since the compatibility between B)) and the polyrotaxane compound (C) is improved, a low haze value as described above can be achieved. When the haze value is the above value, the pressure-sensitive adhesive has excellent optical characteristics, and is preferable for optical applications such as display panels.

  Moreover, it is preferable that the adhesive force which concerns on this embodiment is 0.1-25 N / 25mm with respect to an alkali free glass, It is especially preferable that it is 2-20 N / 25mm, Furthermore, 3-15 N / It is preferably 25 mm. In addition, adhesive force here refers to 180 degree peeling adhesive force (peeling speed 300 mm / min) according to JIS Z0237, and after applying and applying to 0.5MPa and 50 degreeC for 20 minutes, to a to-be-adhered body, It shall be measured after being left for 24 hours under conditions of 23 ° C. and 50% RH. 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.

  Furthermore, the pressure-sensitive adhesive according to this embodiment preferably has a gel fraction of 15 to 90%, particularly preferably 20 to 80%, and more preferably 25 to 70%. When the gel fraction of the pressure-sensitive adhesive according to the present embodiment, that is, the degree of crosslinking, is in the above range, the pressure-sensitive adhesive can be excellent in both light leakage resistance and durability.

  In addition, the gel fraction of an adhesive is a value at the time of sticking (after progress of an aging period). Specifically, it refers to the gel fraction after the adhesive composition is applied to a release sheet and heat-treated, and then stored for 7 days in an environment of 23 ° C. and 50% RH. This is because the gel fraction of the pressure-sensitive adhesive fluctuates before the aging period. From this point of view, if it is unclear whether the aging period has elapsed or not, it is only necessary that the gel fraction be within the above range after being stored again for 23 days in an environment of 23 ° C. and 50% RH. .

  The pressure-sensitive adhesive described above 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) It is suitable for adhesion between a retardation plate (retardation film) and a glass substrate. The pressure-sensitive adhesive layer formed by the pressure-sensitive adhesive according to the present embodiment is very excellent in stress relaxation properties. Therefore, even when the dimensional change of the adherend is large, the pressure-sensitive adhesive layer generates stress that can be generated by the dimensional change. Therefore, it becomes difficult to peel off from the adherend over a long period of time, and light leakage can be effectively prevented when used in the optical member as described above. That is, the pressure-sensitive adhesive according to the present embodiment achieves both light leakage resistance and durability, has a low haze value, and is excellent in optical characteristics.

[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 crosslinking 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; urethane Foam, foam such as polyethylene foam; polyester film such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyurethane film, polyethylene film, polypropylene film, cellulose film such as triacetylcellulose, polyvinyl chloride film, polychlorinated Vinylidene film, polyvinyl alcohol film, ethylene-vinyl acetate copolymer film, polystyrene film, polycarbonate film, acrylic resin film, norbornene resin film, cycloolefin resin Plastic films such as Irumu; 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. Among them, the polarizing plate (polarizing film) and the retardation plate (retardation film) are easy to shrink and have a large dimensional change, so that the pressure-sensitive adhesive of the present embodiment (the pressure-sensitive adhesive layer 11) is formed from the viewpoint of light leakage resistance. It is suitable as an object to be performed.

  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.

  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 is applied to the release surface of the release sheet 12, and heat treatment is performed to form the pressure-sensitive adhesive layer 11. A base material 13 is laminated on the agent layer 11. Then, it is preferable to provide a curing period.
In addition, about the conditions of heat processing and curing, it is as having mentioned above.

  Moreover, in order to manufacture the said adhesive sheet 1B, the coating solution containing the said adhesive composition is apply | coated to the peeling surface of one peeling sheet 12a (or 12b), heat processing is performed, and the adhesive layer 11 is formed. After that, the release surface of the other release sheet 12b (or 12a) is overlaid on the adhesive layer 11.

  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 very excellent in stress relaxation properties, even when applied to adhesion of a polarizing plate, for example, the stress that can be generated by deformation of the polarizing plate is applied to the pressure-sensitive adhesive layer 11. It can be assumed that excellent light leakage resistance and high durability can be exhibited.

  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 polymer (A) In a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping device, and a nitrogen introduction tube, 98.5 parts by mass of n-butyl acrylate, 1.5 parts by mass of 2-hydroxyethyl acrylate 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, the molecular weight of a part of the obtained solution was measured by the method described later, and the production of a polymer (A) having a weight average molecular weight (Mw) of 1.5 million was confirmed.

2. Preparation of polymer (B) In a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a dropping device and a nitrogen introduction tube, 95.0 parts by mass of n-butyl acrylate, 5.0 parts by mass of acrylic acid, ethyl acetate 200 parts by mass and 0.02 parts 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 the production of a polymer (B) having a weight average molecular weight (Mw) of 1.5 million was confirmed.

3. Preparation of Adhesive Composition 100 parts by mass (solid content converted value) of the polymer (A) obtained in the above step (1) and 5 parts by mass (solid) of the polymer (B) obtained in the above step (2) And a polyrotaxane compound (C) (manufactured by Advanced Soft Materials, trade name “Celum Superpolymer A1000”, solid content concentration 100% by mass) 0.3 part by mass and a crosslinking agent ( As D), 0.6 part by mass of trimethylolpropane xylene diisocyanate adduct (manufactured by Soken Chemical Co., Ltd., trade name “TD-75”) was added. Finally, 0.2 part by mass of 3-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name “KBM403”) is added as a silane coupling agent (E), and the viscosity is increased with sufficient stirring. By diluting with toluene so that it might become 2000 mPa * s / 25 degreeC, the diluted solution of the adhesive composition was obtained.

Here, Table 1 shows the composition of the adhesive composition. Details of the abbreviations and the like described in Table 1 are as follows.
[Polymers (A) and (B)]
BA: n-butyl acrylate AA: acrylic acid MA: methacrylic acid HEA: 2-hydroxyethyl acrylate
[Crosslinking agent (D) / isocyanate type]
XDI: xylene diisocyanate adduct of trimethylolpropane (manufactured by Soken Chemical Co., Ltd., trade name “TD-75”)
TDI: Tolylene diisocyanate adduct of trimethylolpropane (Nippon Polyurethane, trade name “Coronate L”)
[Crosslinking agent (D) / Epoxy]
N, N, N ′, N′-tetraglycidyl-m-xylenediamine (trade name “E-AX”, manufactured by Soken Chemical Co., Ltd.)
[Silane coupling agent (E)]
KBM403: 3-glycidoxypropyltrimethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name “KBM403”)
KBE402: 3-glycidoxypropylmethyldiethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd., trade name “KBE402”)

  After drying the diluted solution of the obtained adhesive composition on the release-treated surface of a release sheet (SP-PET3811, thickness: 38 μm, manufactured by Lintec Co., Ltd.) obtained by releasing one side of a polyethylene terephthalate film with a silicone-based release agent After coating with a knife coater so that the thickness of the adhesive layer became 25 μm, a pressure-sensitive adhesive layer was formed by heat treatment at 90 ° C. for 1 minute.

  Next, a polarizing plate composed of a polarizing film with a discotic liquid crystal layer, and a polarizing plate in which a polarizing film and a viewing angle widening film are integrated, are bonded so that the exposed surface of the adhesive layer and the surface of the discotic liquid crystal layer are in contact with each other. A polarizing plate with an adhesive layer was obtained by curing for 7 days at 23 ° C. and 50% RH.

[Examples 2 to 25, Comparative Examples 1 to 7]
Table 1 shows the types and proportions of each monomer constituting the adhesive composition, the types and blending amounts of the polyrotaxane compound, the crosslinking agent and the silane coupling agent, and the blending ratio of the polymer (A) and the polymer (B). A polarizing plate with a pressure-sensitive adhesive layer was produced in the same manner as in Example 1, except for changing as shown.

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] (Light leakage test)
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 alkali-free glass (Corning Corp., Eagle XG) 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. In addition, the said bonding was performed on the front and back of non-alkali glass so that the polarizing axis may be in a crossed nicols state (polarizing axis: ∠45 °, ∠135 °). In this state, the sample was allowed to stand for 250 hours in an 80 ° C. dry environment, and then left for 2 hours in an environment of 23 ° C. and 50% RH. Using this as a sample, the light leakage resistance was evaluated by the following method. The results are shown in Table 2.

<Evaluation of light leakage: ΔL ^* >
Using the MCPD-2000 manufactured by Otsuka Electronics Co., Ltd., the lightness L ^{* of} each region shown in FIG. 3 in the above sample was measured, and the lightness difference ΔL ^* was expressed by the formula ΔL ^* = [(b + c + d + e) / 4] −a
(Where a, b, c, d, and e are the lightness values at predetermined measurement points (one central portion of each region) in the A region, B region, C region, D region, and E region, respectively. ) To obtain light leakage. A smaller value of ΔL ^* indicates less light leakage.

[Test Example 2] (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 alkali-free glass (Corning Corp., Eagle XG) 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 into the environment of the following durable conditions, and observed using the 10 time magnifier 500 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 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>
・ 60 ℃, relative humidity 90% RH
・ 80 ℃ dry

[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. After peeling the release sheet from this sample and pasting the sample on alkali-free 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 the conditions of 23 ° C. and 50% RH, using a tensile tester (Orientec Co., Ltd., Tensilon), the adhesive strength (adhesion) under the conditions of a peeling speed of 300 mm / min and a peeling angle of 180 °. The adhesive strength after 1 day; N / 25 mm) was measured. The results are shown in Table 2.

[Test Example 4] (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 subjected to a release treatment on the exposed adhesive layer of the release sheet / adhesive layer (thickness: 25 μm) obtained in the production process of the example or the comparative example. The layers were laminated so that the surface side was in contact. Thereby, the adhesive sheet which consists of a structure of a peeling sheet / adhesive layer / release sheet was produced.

  The obtained pressure-sensitive adhesive sheet was cured for 7 days under the conditions of 23 ° C. and 50% RH. Thereafter, the pressure-sensitive adhesive sheet was sampled to a size of 80 mm × 80 mm, the pressure-sensitive adhesive layer was wrapped in a polyester mesh (mesh size 200), and the mass of the pressure-sensitive adhesive alone was weighed with a precision balance. The mass at this time is 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. The gel fraction (%) is represented by (M2 / M1) × 100. The results are shown in Table 2.

[Test Example 5] (Measurement of haze value)
As a measurement sample, an adhesive sheet (cured for 7 days) similar to the adhesive sheet used for measuring 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.

  As is clear from Table 2, the polarizing plate with the pressure-sensitive adhesive layer obtained in the examples is excellent in both light leakage resistance and durability, and the pressure-sensitive adhesive obtained in the examples has a haze value. It was low and excellent in optical characteristics, and also adhesive strength was good.

  The pressure-sensitive adhesive composition and pressure-sensitive adhesive of the present invention are suitable for adhesion of optical members such as polarizing plates and retardation plates, and the pressure-sensitive adhesive sheet of the present invention is for optical members such as polarizing plates and phase difference plates. Suitable as an adhesive sheet.

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

Claims (11)

A first (meth) acrylic acid ester polymer (A) having substantially no carboxyl group and a weight average molecular weight of 500,000 to 2.5 million;
As a monomer unit constituting the polymer, a second (meth) acrylic acid ester polymer (B) containing 1 to 20% by mass of a monomer having a carboxyl group and having a weight average molecular weight of 50,000 to 2.5 million,
A pressure-sensitive adhesive composition containing a polyrotaxane compound (C) having a cyclic oligosaccharide as a cyclic molecule,
The ratio of the second (meth) acrylic acid ester polymer (B) to 100 parts by mass of the first (meth) acrylic acid ester polymer (A) is 0.1 to 30 parts by mass,
Content of the said polyrotaxane compound (C) in the said adhesive composition is 0.1-5.0 mass%, The adhesive composition characterized by the above-mentioned.   The pressure-sensitive adhesive composition according to claim 1, further comprising a crosslinking agent (D).   The pressure-sensitive adhesive according to claim 2, wherein the first (meth) acrylic acid ester polymer (A) has a reactive group capable of reacting with a reactive group of the crosslinking agent (D). Composition.   The pressure-sensitive adhesive composition according to claim 2 or 3, wherein the cyclic molecule of the polyrotaxane compound (C) has a reactive group capable of reacting with a reactive group of the crosslinking agent (D). The first (meth) acrylic acid ester polymer (A) contains, as a monomer unit constituting the polymer, a monomer having a hydroxyl group that is a reactive group,
The cyclic molecule of the polyrotaxane compound (C) has a hydroxyl group as a reactive group,
The said crosslinking agent (D) has an isocyanate group as a reactive group, The adhesive composition as described in any one of Claims 2-4 characterized by the above-mentioned.   The pressure-sensitive adhesive composition according to any one of claims 1 to 5, further comprising a silane coupling agent (E).   The adhesive which bridge | crosslinks the adhesive composition as described in any one of Claims 1-6. 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 7, The adhesive sheet characterized by the above-mentioned.   The pressure-sensitive adhesive sheet according to claim 8, wherein the substrate is an optical member.   The pressure-sensitive adhesive sheet according to claim 9, wherein the optical member is a polarizing plate or a retardation plate. 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 7, The adhesive sheet characterized by the above-mentioned.

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