JP2014162834A - 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 application property into a thick film and following property to ruggedness.SOLUTION: The pressure-sensitive adhesive composition comprises: a (meth)acrylate polymer (A) having a weight average molecular weight of 100000 to 900000 and having a reactive group; a crosslinking agent (B); and a polyrotaxane compound (C) having a cyclic oligosaccharide as a cyclic molecule. The content of the crosslinking agent (B) in the pressure-sensitive adhesive composition is 0.01 to 2 parts by mass with respect to 100 parts by mass of the (meth)acrylate polymer (A); and the content of the polyrotaxane compound (C) in the pressure-sensitive adhesive composition is 0.1 to 30 parts by mass with respect to 100 parts by mass of the (meth)acrylate polymer (A).

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 relates to a pressure-sensitive adhesive composition, a pressure-sensitive adhesive, and a pressure-sensitive adhesive sheet suitable for optical members. It is.

  In recent years, in various electronic devices, a touch panel that serves as both a display device and an input unit is often used. The types of touch panels are mainly resistive film type, capacitance type, optical type and ultrasonic type. Resistance film type includes analog resistance film type and matrix resistance film type. There are types and projection types.

  As a touch panel in a mobile electronic device such as a smartphone or a tablet terminal that has been attracting attention recently, a projected capacitive type is often used. As a projected capacitive touch panel in such mobile electronic devices, for example, in order from the bottom, a liquid crystal display (LCD), an adhesive layer, a transparent conductive film (tin-doped indium oxide: ITO), a glass substrate, a transparent conductive film ( ITO) and a laminate of protective layers such as tempered glass have been proposed.

  In the touch panel as described above, there may be a step due to printing or the like on the surface in contact with the pressure-sensitive adhesive layer. In this case, the pressure-sensitive adhesive layer needs to be formed so as to fill the step. For this purpose, the pressure-sensitive adhesive layer needs to be thick and the pressure-sensitive adhesive layer needs to follow the steps. That is, the pressure-sensitive adhesive used for such a pressure-sensitive adhesive layer is required to have a thick film coatability and a step (unevenness) followability.

  In the inventions described in Patent Documents 1 and 2, the unevenness followability of the pressure-sensitive adhesive layer is improved by blending an oligomer which is a low molecular weight component into the pressure-sensitive adhesive and softening the resulting pressure-sensitive adhesive layer appropriately. .

JP 2011-158458 A JP 2011-162593 A

  However, the pressure-sensitive adhesive obtained by adding a low molecular weight component has a problem that the cohesive force is not sufficient, and the adhesive strength is reduced or foamed when placed under high temperature, resulting in low heat resistance. is there. Further, there are concerns about various problems such as low molecular weight components bleeding out from the pressure-sensitive adhesive layer over time, resulting in decreased adhesion durability and contamination of the adherend.

  This invention is made | formed in view of such an actual condition, and it aims at providing the adhesive composition, adhesive, and adhesive sheet which are excellent in thick film coating property and uneven | corrugated followable | trackability.

  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 100,000 to 900,000 and having a reactive group, and a crosslinking agent (B). And a polyrotaxane compound (C) having a cyclic oligosaccharide as a cyclic molecule, wherein the content of the crosslinking agent (B) in the adhesive composition is the (meth) acrylic It is 0.01-2 mass parts with respect to 100 mass parts of acid ester polymer (A), and content of the said polyrotaxane compound (C) in the said adhesive composition is the said (meth) acrylic acid ester weight. Provided is an adhesive composition that is 0.1 to 30 parts by mass with respect to 100 parts by mass of the combined (A) (Invention 1).

  The pressure-sensitive adhesive composition according to the invention (Invention 1) is excellent in thick film coatability because the weight average molecular weight of the main component (meth) acrylic acid ester polymer (A) is relatively small. By containing a predetermined amount of the polyrotaxane compound (C), the resulting pressure-sensitive adhesive has excellent unevenness followability.

  In the said invention (invention 1), the said (meth) acrylic acid ester polymer (A) contains 1-50 mass% of monomers which have a hydroxyl group as a monomer unit which comprises the said polymer, The said crosslinking agent (B ) Is an isocyanate-based crosslinking agent (Invention 2), or the (meth) acrylic acid ester polymer (A) contains 1 to 30% by mass of a monomer having a carboxyl group as a monomer unit constituting the polymer. It is preferable that the crosslinking agent (B) is at least one selected from the group consisting of an isocyanate crosslinking agent, an epoxy crosslinking agent, and a metal chelate crosslinking agent (Invention 3).

  In the said invention (invention 1-3), it is preferable that the cyclic molecule of the said polyrotaxane compound (C) has a hydroxyl group as a reactive group (invention 4).

  2ndly, this invention provides the adhesive formed by bridge | crosslinking the said adhesive composition (invention 1-4) (invention 5).

  In the said invention (invention 5), it is preferable that a gel fraction is 20 to 90% (invention 6).

  In the said invention (invention 5 and 6), it is preferable that a haze value is 5% or less (invention 7).

  In the said invention (invention 5 and 6), the said transparent adhesive film surface side is made into the said adhesive by the two 125-micrometer-thick plastic films which have the transparent conductive film which consists of tin-doped indium oxide for the said adhesive of 100 micrometers in thickness. The pressure-sensitive adhesive has a haze value of 5% or less when sandwiched so as to be in contact and stored for 120 hours under the conditions of 85 ° C. and 85% RH and then returned to normal temperature and humidity of 23 ° C. and 50% RH. It is preferable (Invention 8).

  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 (inventions 5 to 8). (Invention 9)

  In the said invention (invention 9), it is preferable that the said base material is an optical member (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. A layer is made of the pressure-sensitive adhesive (Invention 5 to 8), and provides a pressure-sensitive adhesive sheet (Invention 11).

  The pressure-sensitive adhesive composition according to the present invention is excellent in thick film coatability due to the relatively small weight average molecular weight of the main component (meth) acrylate polymer, and contains a predetermined amount of a polyrotaxane compound. As a result, the resulting pressure-sensitive adhesive has excellent 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. It is a top view explaining the uneven | corrugated followable | trackability test of an adhesive layer. It is a schematic sectional drawing explaining the uneven | corrugated followable | trackability test of an adhesive layer.

Hereinafter, embodiments of the present invention will be described.
[Adhesive composition]
The pressure-sensitive adhesive composition according to this embodiment (hereinafter referred to as “pressure-sensitive adhesive composition P”) has a weight-average molecular weight of 100,000 to 900,000 and a (meth) acrylic acid ester polymer (A ), A crosslinking agent (B), and a polyrotaxane compound (C) having a cyclic oligosaccharide as a cyclic molecule. 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”.

(1) (Meth) acrylic acid ester polymer (A)
The reactive group possessed by the (meth) acrylic acid ester polymer (A) is a functional group capable of reacting with the crosslinking agent (B), and examples thereof include a hydroxyl group, a carboxyl group, and an amino group. Groups are preferred. That is, the (meth) acrylic acid ester polymer (A) contains a monomer having a hydroxyl group (hydroxyl group-containing monomer) and / or a monomer having a carboxyl group (carboxyl group-containing monomer) as a monomer unit constituting the polymer. It is preferable to do. The (meth) acrylic acid ester polymer (A) is crosslinked by the crosslinking agent (B) via the reactive group. In addition, the functional group containing radically polymerizable unsaturated double bonds, such as a vinyl group and a (meth) acryloyl group, is excluded as the reactive group. In the crosslinking reaction of a (meth) acrylic acid ester polymer having a functional group containing a radical polymerizable unsaturated double bond as a reactive group, it is difficult to control to an appropriate crosslinking density that can exert the effects of the present invention. It is.

  Since the hydroxyl group has high reactivity with the isocyanate group, it is preferable to use an isocyanate-based crosslinking agent as the crosslinking agent (B) described later. Moreover, since a carboxyl group reacts with an isocyanate group, an epoxy group and a metal chelate, the crosslinking agent (B) described later is selected from the group consisting of an isocyanate crosslinking agent, an epoxy crosslinking agent and a metal chelate crosslinking agent. It is preferable to use at least one kind.

  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 ) (Meth) acrylic acid hydroxyalkyl esters such as 3-hydroxybutyl acrylate and 4-hydroxybutyl (meth) acrylate, and the like. Among them, the hydroxyl group in the resulting (meth) acrylic acid ester polymer (A). In view of reactivity with the crosslinking agent (B) and copolymerization with other monomers, 2-hydroxyethyl (meth) acrylate is preferred. These may be used alone or in combination of two or more.

  The (meth) acrylic acid ester polymer (A) preferably contains 1 to 50% by mass, particularly preferably 5 to 40% by mass, of a hydroxyl group-containing monomer as a monomer unit constituting the polymer. Furthermore, it is preferable to contain 15-30 mass%.

  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 (meth) acrylic acid ester polymer (A) preferably contains 1 to 30% by mass, particularly preferably 2 to 25% by mass of a carboxyl group-containing monomer as a monomer unit constituting the polymer. Furthermore, it is preferable to contain 7-20 mass%.

  When the content of the hydroxyl group-containing monomer and the carboxyl group-containing monomer is in the above range, the crosslinked structure formed is favorable, and the resulting pressure-sensitive adhesive has durability suitable for an optical member. .

  In addition, when the content of the hydroxyl group-containing monomer and the carboxyl group-containing monomer is in the above range, the pressure-sensitive adhesive obtained by crosslinking the pressure-sensitive adhesive composition P is returned to room temperature and humidity after being subjected to high temperature and high humidity conditions. Whitening at the time is suppressed. Details of the conditions of high temperature and high humidity will be described later. When the (meth) acrylic acid ester polymer (A) contains a hydroxyl group-containing monomer or a carboxyl group-containing monomer in a relatively large amount as described above, the pressure-sensitive adhesive obtained by crosslinking the pressure-sensitive adhesive composition P contains A fixed amount of hydroxyl group or carboxyl group remains. Hydroxyl groups and carboxyl groups are hydrophilic groups, and when such a hydrophilic group is present in the pressure-sensitive adhesive in a predetermined amount, even when the pressure-sensitive adhesive is placed under high-temperature and high-humidity conditions, It is presumed that the moisture that has entered the agent easily escapes from the adhesive when it returns to normal temperature and humidity, and as a result, whitening of the adhesive is suppressed.

  The (meth) acrylic acid ester polymer (A) preferably contains a (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms as the monomer unit constituting the polymer, particularly the main component. It is preferable to contain as. Thereby, the obtained adhesive can express preferable adhesiveness.

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

  The (meth) acrylic acid ester polymer (A) may contain 30 to 99% by mass of a (meth) acrylic acid alkyl ester having 1 to 20 carbon atoms as the monomer unit constituting the polymer. The content is preferably 40 to 95% by mass, more preferably 50 to 85% by mass.

  The (meth) acrylic acid ester polymer (A) may contain other monomers as monomer units constituting the polymer, if desired. As the other monomer, a monomer having no reactive group is preferable.

  Such other monomers include, for example, (meth) acrylic acid alkoxyalkyl esters such as methoxyethyl (meth) acrylate and ethoxyethyl (meth) acrylate, and aliphatic rings such as cyclohexyl (meth) acrylate (meta Non-crosslinkable acrylamide such as acrylic ester, acrylamide, methacrylamide, etc. Non-crosslinkable tertiary such as N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate Examples thereof include (meth) acrylic acid ester having an amino group, vinyl acetate, and styrene. These may be used alone or in combination of two or more.

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

  The weight average molecular weight of the (meth) acrylic acid ester polymer (A) is 100,000 to 900,000, preferably 200,000 to 700,000, particularly preferably 250,000 to 600,000. In addition, the weight average molecular weight in this specification is the value of polystyrene conversion measured by the gel permeation chromatography (GPC) method.

  Since the weight average molecular weight of the (meth) acrylic acid ester polymer (A) which is the main component of the adhesive composition P is relatively small as described above, the adhesive composition P has a high concentration (low solvent amount). In addition, it can be applied at a low viscosity, which enables thick film coating. Specifically, it can apply so that the thickness of the adhesive layer after drying may be 10-200 micrometers. When the weight average molecular weight of the (meth) acrylic acid ester polymer (A) exceeds 900,000, the above effect cannot be obtained. On the other hand, when the weight average molecular weight of the (meth) acrylic acid ester polymer (A) is less than 100,000, the resulting pressure-sensitive adhesive is inferior in durability.

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

(2) Crosslinking agent (B)
The adhesive composition P contains a crosslinking agent (B) to form a three-dimensional network structure by crosslinking the (meth) acrylic acid ester polymer (A), and the resulting adhesive is used for an optical member. Suitable durability can be provided.

  As a crosslinking agent (B), what is necessary is just to react with the reactive group which (meth) acrylic acid ester polymer (A) has, for example, an isocyanate type crosslinking agent, an epoxy type crosslinking agent, an amine type crosslinking agent, Melamine-based crosslinking agents, aziridine-based crosslinking agents, hydrazine-based crosslinking agents, aldehyde-based crosslinking agents, oxazoline-based crosslinking agents, metal alkoxide-based crosslinking agents, metal chelate-based crosslinking agents, metal salt-based crosslinking agents, ammonium salt-based crosslinking agents, etc. Can be mentioned. A crosslinking agent (B) can be used individually by 1 type or in combination of 2 or more types.

  As described above, when the (meth) acrylic acid ester polymer (A) has a hydroxyl group as a reactive group, it is preferable to use an isocyanate-based crosslinking agent, and the (meth) acrylic acid ester polymer (A) In the case of having a carboxyl group as the reactive group, it is preferable to use at least one selected from the group consisting of an isocyanate crosslinking agent, an epoxy crosslinking agent and a metal chelate crosslinking agent.

  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 biuret bodies, isocyanurate bodies, and adduct bodies that are a reaction product with a low-molecular active hydrogen-containing compound such as ethylene glycol, propylene glycol, neopentyl glycol, trimethylolpropane, castor oil, and the like. Among them, trimethylolpropane-modified aromatic polyisocyanate from the point of reactivity with the reactive group of the (meth) acrylic acid ester polymer (A) , In particular trimethylolpropane modified xylylene diisocyanate and trimethylolpropane-modified tolylene diisocyanate is preferable.

  Examples of the epoxy crosslinking agent include 1,3-bis (N, N′-diglycidylaminomethyl) cyclohexane, N, N, N ′, N′-tetraglycidyl-m-xylylenediamine, ethylene glycol diglycidyl. Examples include ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane diglycidyl ether, diglycidyl aniline, diglycidyl amine and the like.

  As the metal chelate-based crosslinking agent, there are chelate compounds whose metal atoms are aluminum, zirconium, titanium, zinc, iron, tin, etc., but aluminum chelate compounds are preferable from the viewpoint of performance.

  Examples of the aluminum chelate compound include diisopropoxy aluminum monooleyl acetoacetate, monoisopropoxy aluminum bis oleyl acetoacetate, monoisopropoxy aluminum monooleate monoethyl acetoacetate, diisopropoxy aluminum monolauryl acetoacetate, diisopropoxy Aluminum monostearyl acetoacetate, diisopropoxy aluminum monoisostearyl acetoacetate, monoisopropoxy aluminum mono-N-lauroyl-β-alanate monolauryl acetoacetate, aluminum trisacetylacetonate, monoacetylacetonate aluminum bis (isobutylacetate Acetate) chelate, monoacetylacetonate aluminum (2-ethylhexyl acetoacetate) chelate, monoacetylacetonate aluminum bis (dodecylacetoacetate) chelate, monoacetylacetonate aluminum bis (oleyl acetoacetate) chelate, and the like.

  Content of the crosslinking agent (B) in the adhesive composition P needs to be 0.01-2 mass parts with respect to 100 mass parts of (meth) acrylic acid ester polymer (A), 0 It is preferably 0.01 to 1 part by mass, particularly preferably 0.02 to 0.8 part by mass, and further preferably 0.03 to 0.6 part by mass. The durability improvement effect by the said crosslinking agent (B) is acquired as content of a crosslinking agent (B) is 0.01 mass part or more. When content of a crosslinking agent (B) exceeds 2 mass parts, the degree of bridge | crosslinking will become excess and the uneven | corrugated followable | trackability of the adhesive which is obtained will fall. Further, when the (meth) acrylic acid ester polymer (A) contains a hydroxyl group-containing monomer or a carboxyl group-containing monomer in the amount described above, the hydroxyl group or carboxyl group reacts with the crosslinking agent (B) in a large amount, thereby causing an adhesive. There is a possibility that the amount remaining in the inside becomes small and the above-mentioned whitening suppression effect cannot be obtained.

(3) Polyrotaxane compound (C)
The polyrotaxane compound (C) contained in the pressure-sensitive adhesive composition P 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. It is. In the polyrotaxane compound (C), the cyclic molecule can freely move (sliding) on the linear molecule. When the pressure-sensitive adhesive composition P contains a predetermined amount of the polyrotaxane compound (C) having such a mechanical bond, the obtained pressure-sensitive adhesive has excellent stress relaxation properties and unevenness following properties. Therefore, even when a level difference exists on the adherend, it is difficult to form a gap between the level difference and the pressure-sensitive adhesive layer, and the pressure-sensitive adhesive layer can fill the level difference.

  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. Moreover, since the cyclic oligosaccharide which is not modified has a hydroxyl group, when the crosslinking agent (B) is, for example, an isocyanate crosslinking agent, the reaction with the isocyanate crosslinking agent is easy. 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 examples of the cyclic oligosaccharide include cyclodextrins such as α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin and derivatives thereof, and α-cyclodextrin and derivatives thereof are 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) that can react with the reactive group (b) of the cross-linking agent (B). 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 reactive group (b) of the crosslinking agent (B) is an isocyanate group, the cyclic molecule of the polyrotaxane compound (C) preferably has a hydroxyl group as the reactive group (c).

  In the pressure-sensitive adhesive composition P, the crosslinking agent (B), the (meth) acrylic acid ester polymer (A), the crosslinking agent (B), and the polyrotaxane compound (C) react with each other via the crosslinking agent (B). When the (meth) acrylic acid ester polymer (A) and the polyrotaxane compound (C) are crosslinked, the polyrotaxane compound (C) allows the cyclic molecule to freely move on the linear molecule, thereby producing a crosslinked product. As a result, the flexibility is significantly improved. Thereby, the obtained adhesive exhibits a very high stress relaxation property and becomes more excellent in unevenness followability.

  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 the crosslinking agent (B). 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 crosslinking point, and the effect of the crosslinking point as a whole polyrotaxane compound (C) (sliding effect of the crosslinking point) As a result, there is a possibility that sufficient unevenness followability 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 above substituents into the reactive group (c) is preferably 10 to 90%, 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 a (meth) acrylic acid ester polymer (A) 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 30% by mass, preferably 0.5 to 15% by mass, and particularly 0.7 to 10%. It is preferable that it is mass%. When the content of the polyrotaxane compound (C) is less than 0.1% by mass, the uneven follow-up effect by the polyrotaxane compound (C) may not be obtained. On the other hand, when the content of the polyrotaxane compound (C) exceeds 30% by mass, the compatibility with the (meth) acrylic acid ester polymer (A) is deteriorated, and the haze value of the obtained pressure-sensitive adhesive may be increased. .

(4) Various additives For the adhesive composition P, if desired, various additives usually used for acrylic adhesives, such as silane coupling agents, antistatic agents, tackifiers, antioxidants, ultraviolet rays Absorbers, light stabilizers, softeners, fillers, refractive index adjusters and the like can be added.

[Method for producing adhesive composition]
The pressure-sensitive adhesive composition P produced a (meth) acrylic acid ester polymer (A), and the obtained (meth) acrylic acid ester polymer (A), a crosslinking agent (B), and a polyrotaxane compound (C). And, if desired, can be produced by adding an additive.

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

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

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

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

  When the (meth) acrylic acid ester polymer (A) is obtained, a crosslinking agent (B), a polyrotaxane compound (C), and optionally additives are added to the solution of the (meth) acrylic acid ester polymer (A). Then, by sufficiently mixing, the adhesive composition P is obtained.

  Here, since the weight average molecular weight of the (meth) acrylic acid ester polymer (A) in the pressure-sensitive adhesive composition P is relatively small and the viscosity is low, the pressure-sensitive adhesive composition P is directly applied as a coating solution after solution polymerization. Is possible. Therefore, a diluting solvent for diluting the adhesive composition P after polymerization is usually unnecessary (however, it does not prevent the use of the diluting solvent). Thereby, the adhesive composition P can be applied at a high concentration, and thick film coating becomes possible. Specifically, it can be applied such that the thickness of the pressure-sensitive adhesive layer after drying is 5 to 200 μm, preferably 10 to 150 μm, particularly preferably 40 to 100 μm.

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

  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. 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 (meth) acrylic acid ester polymer (A) and the polyrotaxane compound (C) are favorably crosslinked through the crosslinking agent (B).

  When the pressure-sensitive adhesive obtained by crosslinking the pressure-sensitive adhesive composition P has the same amount of the cross-linking agent (B), the amount of elongation at break increases as the amount of the polyrotaxane compound (C) increases, and the stress at break The value of tends to increase. Therefore, in the conventional adjustment method based on the amount of the crosslinking agent, it is possible to control the balance between the elongation at break and the breaking stress of the pressure-sensitive adhesive having a trade-off relationship.

  The gel fraction of the pressure-sensitive adhesive according to this embodiment is preferably 20 to 95%, particularly preferably 30 to 90%, and further preferably 40 to 80%. When the gel fraction is less than 20%, the cohesive force of the pressure-sensitive adhesive is insufficient, and durability and reworkability may be deteriorated. On the other hand, when the gel fraction exceeds 95%, the unevenness followability may be extremely lowered. In addition, the said gel fraction is a value about the adhesive formed after the curing period passed (for example, after storing in 23 degreeC and 50% RH environment for 7 days). If it is unclear whether the curing period has elapsed, after storing again for 7 days in an environment of 23 ° C. and 50% RH, the gel fraction should be within the above range.

[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 P.

  The thickness of the pressure-sensitive adhesive layer 11 is appropriately determined according to the height of the level difference of the adherend to be filled, but is usually preferably 10 to 300 μm, particularly preferably 15 to 250 μm, It is preferable that it is 40-200 micrometers. The pressure-sensitive adhesive layer 11 may be formed as a single layer or may be formed by laminating a plurality of layers.

  There is no restriction | limiting in particular as the base material 13, What was used as a base material sheet of a normal adhesive sheet can be used. For example, in addition to the desired optical member, woven or non-woven fabric using fibers such as rayon, acrylic, polyester, etc .; synthetic paper; paper such as fine paper, glassine paper, impregnated paper, coated paper; metal such as aluminum and copper Foils; foams such as urethane foam and polyethylene foam; polyester films such as polyethylene terephthalate (PET), polybutylene terephthalate and polyethylene naphthalate, polyurethane films, polyethylene films, polypropylene films, cellulose films such as triacetylcellulose, poly Vinyl chloride film, polyvinylidene chloride film, polyvinyl alcohol film, ethylene-vinyl acetate copolymer film, polystyrene film, polycarbonate film, acrylic resin film, norbornene resin film, paper Plastic films such as Russia olefin 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, it is 10-500 micrometers normally, Preferably it is 50-300 micrometers, Especially preferably, it is 80-150 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 P is applied to the release surface of the release sheet 12, and a heat treatment is performed to form a coating layer. The substrate 13 is laminated on the substrate. When a curing period is required, a curing period is set, and when the curing period is unnecessary, the coating layer becomes the pressure-sensitive adhesive layer 11 as it is. Thereby, the said adhesive sheet 1A is obtained. 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 P was apply | coated to the peeling surface of one peeling sheet 12a (or 12b), and the heat treatment was performed, and the coating layer was formed. Thereafter, the release surface of the other release sheet 12b (or 12a) is overlaid on the coating layer. When a curing period is required, a curing period is set, and when the curing period is unnecessary, the coating layer becomes the pressure-sensitive adhesive layer 11 as it is. Thereby, the said adhesive sheet 1B is obtained.

  For example, a bar coating method, a knife coating method, a roll coating method, a blade coating method, a die coating method, a gravure coating method, or the like can be used as a method for applying the coating solution of the adhesive composition P. As described above, the adhesive composition P has a low viscosity and can be applied at a high concentration, so that thick film coating is possible.

  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.

  For example, in order to manufacture a laminate of a liquid crystal cell having a glass substrate and a glass substrate having a desired functional layer, as an example, first, one release sheet 12a (or 12b) of the adhesive sheet 1B is peeled off. And the adhesive layer 11 which the adhesive sheet 1B exposed, and the surface by the side of the functional layer of a glass substrate are bonded. Next, 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 and the glass substrate of the liquid crystal cell are bonded.

  The type of the glass substrate is not particularly limited. For example, chemically tempered glass, alkali-free glass, quartz glass, soda lime glass, barium / strontium-containing glass, aluminosilicate glass, lead glass, borosilicate glass, barium Examples thereof include borosilicate glass. Although the thickness of a glass substrate is not specifically limited, Usually, it is 0.1-5 mm, Preferably it is 0.2-2 mm.

  In addition, the pressure-sensitive adhesive layer 11 according to the present embodiment specifically includes adhesion between optical members such as a polarizing plate (polarizing film) and a retardation plate (retarding film), a polarizing plate (polarizing film), and a retardation. It is suitable for adhesion between a plate (retardation film) and a glass substrate, between transparent electrode films, between a transparent electrode film and a hard coat film, or between a glass substrate and a glass substrate. The glass substrate may be a glass substrate constituting a liquid crystal cell, for example. Various functional layers (transparent conductive film, metal layer, silica layer, etc.) may be provided on the surface of the glass substrate on the pressure-sensitive adhesive side.

  Here, as for adhesive sheet 1A concerning this embodiment, it is preferred that adhesiveness to non-alkali glass is 0.1-25 N / 25 mm, and it is especially preferred that it is 2-20 N / 25 mm. In addition, although the adhesive force here means the adhesive force measured by the 180 degree peeling method according to JIS Z0237: 2009, the measurement sample has a width of 25 mm and a length of 100 mm, and the measurement sample is attached. After being applied to the body by applying pressure at 0.5 MPa and 50 ° C. for 20 minutes, the sample was left for 24 hours under conditions of normal pressure, 23 ° C. and 50% RH, and then measured at a peeling rate of 300 mm / min. To do.

  Moreover, when the (meth) acrylic acid ester polymer (A) contains a hydroxyl group-containing monomer or a carboxyl group-containing monomer in the amount described above, the pressure-sensitive adhesive layer 11 obtained by crosslinking the pressure-sensitive adhesive composition P is a predetermined amount. It has a hydroxyl group or a carboxyl group. Thereby, after giving high temperature high humidity conditions, whitening of the adhesive when it returns to normal temperature is suppressed. For example, the adhesive layer 11 having a thickness of 100 μm is sandwiched between two 125 μm-thick plastic films having a transparent conductive film made of tin-doped indium oxide so that the transparent conductive film surface side is in contact with the adhesive layer 11, The haze value of the pressure-sensitive adhesive layer 11 was measured according to JIS K7136: 2000 when stored at 85 ° C. and 85% RH for 120 hours and then returned to normal temperature and humidity of 23 ° C. and 50% RH. Value) is preferably 5% or less, particularly preferably 3% or less, and further preferably 2.5% or less. In addition, the measurement of the said haze value shall be taken out within 30 minutes after taking out from 85 degreeC and 85% RH atmosphere.

  The pressure-sensitive adhesive layer 11 according to this embodiment preferably has the above haze value even in a normal state. When the haze value is 5% or less, the transparency is high and the optical application is suitable.

  In addition, the pressure-sensitive adhesive layer 11 according to this embodiment can be preferably used for an optical member, and can be particularly preferably used for an adherend having a step. Here, the height of the step is preferably 2 to 50 μm, and particularly preferably 5 to 30 μm.

  In the above pressure-sensitive adhesive sheets 1A and 1B, the pressure-sensitive adhesive layer can be formed thick, and the pressure-sensitive adhesive layer is excellent in uneven followability, so that even when the adherend has a level difference, the level difference and the pressure-sensitive adhesive layer It is difficult to form a gap between the adhesive layer and the pressure-sensitive adhesive layer can fill the step. Further, according to the pressure-sensitive adhesive sheets 1A and 1B when the (meth) acrylic acid ester polymer (A) contains the hydroxyl group-containing monomer or the carboxyl group-containing monomer in the above-described amount, the obtained member is placed under high temperature and high humidity. Even if it returns to normal temperature normal humidity after putting, it can suppress that the adhesive layer 11 whitens.

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

  For example, the release sheet 12 of the adhesive sheet 1A may be omitted, or one of the release sheets 12a and 12b in the adhesive sheet 1B may be omitted.

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

[Example 1]
1. Preparation of (meth) acrylic acid ester polymer In a reaction vessel equipped with a stirrer, thermometer, reflux condenser, dropping device and nitrogen introducing tube, 60 parts by mass of 2-ethylhexyl acrylate, 20 parts by mass of methyl methacrylate, acrylic acid 20 parts by mass of 2-hydroxyethyl, 150 parts by mass of ethyl acetate, and 0.15 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 a method described later, and production of a (meth) acrylic acid ester polymer (A) having a weight average molecular weight of 600,000 was confirmed.

2. Preparation of Adhesive Composition 100 parts by mass of the (meth) acrylic acid ester polymer (A) obtained in the above step (1) (in terms of solid content; the same shall apply hereinafter) and trimethylolpropane as a crosslinking agent (B) 0.3 parts by mass of modified tolylene diisocyanate (manufactured by Nippon Polyurethane Co., Ltd., trade name “Coronate L”) and polyrotaxane compound (C) (manufactured by Advanced Soft Materials, trade name “Celum Superpolymer A1000”) 0.5 A mass part was mixed and sufficiently stirred to obtain a coating solution of the adhesive composition (solid content concentration: 40% by mass).

Here, Table 1 shows the composition of the adhesive composition. Details of the abbreviations and the like described in Table 1 are as follows.
[(Meth) acrylic acid ester polymer (A)]
2EHA: 2-ethylhexyl acrylate MMA: methyl methacrylate HEA: 2-hydroxyethyl acrylate BA: n-butyl acrylate MA: methyl acrylate AA: acrylic acid [crosslinking agent (B)]
Isocyanate-based crosslinking agent-TDI: trimethylolpropane-modified tolylene diisocyanate (manufactured by Nippon Polyurethane Co., Ltd., trade name “Coronate L”)
Isocyanate-based crosslinking agent-XDI: trimethylolpropane-modified xylylene diisocyanate (manufactured by Soken Chemical Co., Ltd., trade name “TD-75”)
Epoxy-based cross-linking agent: N, N, N ′, N′-tetraglycidyl-m-xylylenediamine (trade name “E-AX”, manufactured by Soken Chemical Co., Ltd.)
Metal chelate crosslinking agent: Aluminum chelate compound (manufactured by Soken Chemical Co., Ltd., trade name “M-5A”)

3. Manufacture of an adhesive sheet The coating liquid of the obtained adhesive composition is a release sheet (SP-PET3811, manufactured by Lintec Corporation, thickness: 38 μm) obtained by releasing one side of a polyethylene terephthalate (PET) film with a silicone release agent. The surface to be peeled was coated with a knife coater so that the thickness after drying was 50 μm, and then heat-treated at 90 ° C. for 3 minutes to form a coating layer.

  Next, a release sheet (SP-PET3801, manufactured by Lintec Corporation, thickness: 38 μm) obtained by releasing one side of the PET film with a silicone release agent is in contact with the exposed side of the release layer of the release layer. Thus, the adhesive sheet which consists of a structure of a peeling sheet / adhesive layer (thickness: 50 micrometers) / release sheet was produced by curing for 7 days on conditions of 23 degreeC and 50% RH.

[Examples 2-33, Comparative Examples 1-9]
Kind and ratio of each monomer constituting (meth) acrylate polymer (A), weight average molecular weight of (meth) acrylate polymer (A), kind and blending amount of crosslinking agent (B), and polyrotaxane Except changing the compounding quantity of a compound (C) as shown in Table 1, it carried out similarly to Example 1, and produced the adhesive sheet which consists of a structure of a peeling sheet / adhesive layer / release sheet.

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)
The pressure-sensitive adhesive sheets obtained in Examples or Comparative Examples were 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 2] (Measurement of adhesive strength)
One release sheet is peeled off from the pressure-sensitive adhesive sheet obtained in Examples or Comparative Examples, and the exposed pressure-sensitive adhesive layer is bonded to an easy-adhesion PET film (PET100A4300, thickness: 100 μm, manufactured by Toyobo Co., Ltd.), and then the laminate. Was cut to prepare a sample having a width of 25 mm and a length of 100 mm. The other release sheet is peeled off from this sample, and the sample is affixed to an alkali-free glass (Corning Corp., Eagle XG) through the exposed adhesive layer, and then 0.5 MPa, 50 in an autoclave manufactured by Kurihara Seisakusho. Pressurized at 20 ° C. for 20 minutes. Then, after leaving for 24 hours under the conditions of 23 ° C. and 50% RH, using a tensile tester (Orientec, Tensilon), in accordance with JIS Z0237: 2009, a peeling speed of 300 mm / min, a peeling angle of 180 The adhesive strength (N / 25 mm) was measured under the condition of °. The results are shown in Table 2.

[Test Example 3] (Measurement of haze value)
About the adhesive layer (thickness: 50 micrometers) of the adhesive sheet obtained by the Example or the comparative example, haze value (%) according to JISK7136: 2000 using a haze meter (Nippon Denshoku Industries Co., Ltd. make, NDH2000). ) Was measured. The results are shown in Table 2.

[Test Example 4] (Moisture and heat whitening evaluation)
One of the pressure-sensitive adhesive sheets obtained in Examples or Comparative Examples was peeled off, and the exposed pressure-sensitive adhesive layer was formed into a PET film (ITO-PET film; Oike Industry Co., Ltd.) having a transparent conductive film made of tin-doped indium oxide (ITO). It was bonded to an ITO surface having a total thickness of 125 μm. Next, the other release sheet was peeled off, and the exposed pressure-sensitive adhesive layer was bonded to an ITO-PET film (manufactured by Oike Kogyo Co., Ltd., total thickness 125 μm) in the same manner as described above. The obtained laminate was cut to prepare a sample having a size of 50 mm × 50 mm.

The above sample was stored for 120 hours under conditions of 85 ° C. and 85% RH, then returned to room temperature and normal humidity of 23 ° C. and 50% RH, and the haze value of the adhesive layer was measured (85 ° C., 85% Take out from RH atmosphere and measure within 30 minutes). The haze value was measured according to JIS K7136: 2000 using a haze meter (Nippon Denshoku Industries Co., Ltd., NDH2000). Based on the measured haze value, the moisture and heat whitening resistance was evaluated according to the following criteria. The results are shown in Table 2.
◎: Haze value is 2.5% or less ○: Haze value is more than 2.5% and less than 5% ×: Haze value is 5% or more

[Test Example 5] (Tensile test)
A plurality of the above-mentioned pressure-sensitive adhesive layers were laminated so that the total thickness of the pressure-sensitive adhesive layers in the pressure-sensitive adhesive sheets obtained in Examples or Comparative Examples was 500 μm and only the outermost release sheet of the laminate remained. The obtained laminate was allowed to stand in an atmosphere of 23 ° C. and 50% RH for 2 weeks, and then a 10 mm wide × 75 mm long sample was cut out from the laminate, and the release sheet laminated on the outermost layer of the laminate was peeled off. Then, the sample is set so that the sample measurement site is 10 mm wide × 20 mm long (extension direction), and the tensile speed is measured using a tensile tester (Orientec, Tensilon) in an environment of 23 ° C. and 50% RH. The film was stretched at 200 mm / min, and the breaking elongation (%) and breaking stress (N / mm ² ) were measured. The results are shown in Table 2.

[Test Example 6] (Concavity and convexity followability test)
One release sheet is peeled off from the pressure-sensitive adhesive sheet obtained in Examples or Comparative Examples, and the exposed pressure-sensitive adhesive layer is bonded to an easy-adhesion PET film (PET100A4300, thickness: 100 μm, manufactured by Toyobo Co., Ltd.), and then the laminate. Was cut into a size of 50 mm × 50 mm and used as a sample.

  As shown in FIGS. 3 and 4, a PET film having a size of 20 mm × 20 mm and a thickness of 25 μm or 50 μm was placed on a soda lime glass having a size of 70 mm × 70 mm and a thickness of 1.1 mm. And after peeling a peeling sheet from the said sample and sticking the said sample to soda lime glass so that the adhesive surface of the said sample may seal PET film with a thickness of 25 micrometers or 50 micrometers, it puts on the autoclave by Kurihara Seisakusho Co., Ltd. And pressurized at 0.5 MPa and 50 ° C. for 20 minutes.

Next, after storage for 48 hours under the conditions of 60 ° C. and 90% RH, the temperature is returned to normal temperature and normal humidity of 23 ° C. and 50% RH, and the adhesive generated near the end of the sealed PET film. Lifting length L of the agent layer (the distance obtained by arbitrarily measuring the distance from the end of the PET film having a thickness of 25 μm or 50 μm to the bonded portion of the pressure-sensitive adhesive layer and soda lime glass and averaging them) Was measured. The evaluation criteria are as follows. The results are shown in Table 2.
◎: Floating length L is less than 0.3 mm ○: Floating length L is 0.3 mm or more and less than 0.5 mm ○ △: Floating length L is 0.5 mm or more and less than 0.8 mm △: Floating length L is 0.8 mm or more and less than 1.0 mm X: Floating length L is 1.0 mm or more

  As can be seen from Table 2, the pressure-sensitive adhesive layers obtained in the examples were excellent in uneven followability, and whitening when the temperature returned to room temperature after high-temperature and high-humidity conditions was suppressed.

  The pressure-sensitive adhesive of the present invention is suitable for adhesion of optical members such as polarizing plates and glass substrates, 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 glass substrates.

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

Claims (11)

(Meth) acrylic acid ester polymer (A) having a weight average molecular weight of 100,000 to 900,000 and having a reactive group;
A crosslinking agent (B);
A pressure-sensitive adhesive composition containing a polyrotaxane compound (C) having a cyclic oligosaccharide as a cyclic molecule,
Content of the said crosslinking agent (B) in the said adhesive composition is 0.01-2 mass parts with respect to 100 mass parts of said (meth) acrylic acid ester polymers (A),
Content of the said polyrotaxane compound (C) in the said adhesive composition is 0.1-30 mass parts with respect to 100 mass parts of said (meth) acrylic acid ester polymers (A), It is characterized by the above-mentioned. An adhesive composition. The (meth) acrylic acid ester polymer (A) contains 1 to 50% by mass of a monomer having a hydroxyl group as a monomer unit constituting the polymer,
The pressure-sensitive adhesive composition according to claim 1, wherein the crosslinking agent (B) is an isocyanate-based crosslinking agent. The (meth) acrylic acid ester polymer (A) contains 1 to 30% by mass of a monomer having a carboxyl group as a monomer unit constituting the polymer.
The pressure-sensitive adhesive composition according to claim 1, wherein the crosslinking agent (B) is at least one selected from the group consisting of an isocyanate-based crosslinking agent, an epoxy-based crosslinking agent, and a metal chelate-based crosslinking agent.   The pressure-sensitive adhesive composition according to any one of claims 1 to 3, wherein the cyclic molecule of the polyrotaxane compound (C) has a hydroxyl group as a reactive group.   The adhesive which bridge | crosslinks the adhesive composition as described in any one of Claims 1-4.   The pressure-sensitive adhesive according to claim 5, wherein the gel fraction is 20 to 90%.   The pressure-sensitive adhesive according to claim 5 or 6, wherein a haze value is 5% or less.   The pressure-sensitive adhesive having a thickness of 100 μm is sandwiched between two 125 μm-thick plastic films having a transparent conductive film made of tin-doped indium oxide so that the surface of the transparent conductive film is in contact with the pressure-sensitive adhesive, and 85 ° C. and 85% RH. The haze value of the pressure-sensitive adhesive is 5% or less when stored for 120 hours under the above conditions and then returned to room temperature and normal humidity of 23 ° C. and 50% RH. The adhesive as described. A pressure-sensitive adhesive sheet comprising a base material and a pressure-sensitive adhesive layer,
The said adhesive layer consists of an adhesive as described in any one of Claims 5-8, The adhesive sheet characterized by the above-mentioned.   The pressure-sensitive adhesive sheet according to claim 9, wherein the substrate 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 as described in any one of Claims 5-8, The adhesive sheet characterized by the above-mentioned.

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