JP6403186B2 - Pressure-sensitive adhesive layer, pressure-sensitive adhesive sheet, and method for producing pressure-sensitive adhesive layer - Google Patents

Description

  The present invention relates to a pressure-sensitive adhesive layer, a pressure-sensitive adhesive sheet, and a method for producing a pressure-sensitive adhesive layer.

  Conventionally, an acrylic pressure-sensitive adhesive sheet having an acrylic pressure-sensitive adhesive layer has adhesive properties such as adhesiveness, repulsion resistance, and retention (cohesion), and heat resistance, light resistance, weather resistance, and oil resistance. Because of its excellent aging properties, it is used in a wide range of fields. Above all, on various adherends (joining objects) such as metal materials such as stainless steel and aluminum, glass materials, polyolefin resins such as polyethylene, polypropylene and polystyrene, and various plastic materials such as ABS resin, acrylic resin and polycarbonate resin. On the other hand, adhesive properties having high reliability are required.

  As a method for enhancing the adhesion characteristics of an acrylic pressure-sensitive adhesive sheet to an adherend, a method of adding a tackifier resin (tackifier) to the acrylic pressure-sensitive adhesive composition constituting the acrylic pressure-sensitive adhesive layer is known. . For example, what added the rosin resin and the hydrogenated petroleum-type resin as tackifying resin with the acrylic polymer is disclosed (patent documents 1 and 2).

  In addition, acrylic adhesive sheets have adhesive properties for adherends with low surface energy (low polarity) typified by polyolefin resins such as polyethylene and polypropylene, which are often used in home appliances, building materials, automotive interior / exterior materials, etc. There is also a strong demand for improvement. On the other hand, in the acrylic pressure-sensitive adhesive sheet obtained by the acrylic pressure-sensitive adhesive composition to which the above-mentioned tackifying resin such as rosin resin is added, the low surface energy (low polarity) adherend such as polyolefin resin is used. There is a problem that sufficient adhesive properties cannot be obtained.

  Further, as the tackifying resin, a terpene resin may be used instead of the rosin resin, but the terpene resin has insufficient compatibility with the acrylic polymer and may have poor reliability in adhesive properties. is there.

  Patent Document 3 discloses an acrylic pressure-sensitive adhesive sheet obtained from a pressure-sensitive adhesive composition containing a (meth) acrylic monomer, a block copolymer, a photoinitiator, and a hydrogenated tackifier, a low surface energy polyolefin, and the like. It is disclosed that it is affixed to the adherend and has excellent adhesiveness. However, the acrylic pressure-sensitive adhesive sheet has a problem that good results cannot be obtained with respect to retention and repulsion resistance with respect to polyolefin having a low surface energy.

JP-A-6-207151 Japanese National Patent Publication No. 11-504054 JP 2010-1226697 A

  Therefore, as a result of intensive studies to solve the above problems, the present inventors have found the following pressure-sensitive adhesive layer and have completed the present invention.

  That is, the pressure-sensitive adhesive layer of the present invention contains a rubber-based polymer (A), an acrylic polymer (B), and a hydrogenated tackifying resin (C), and also contains a rubber-based polymer (A). A pressure-sensitive adhesive layer in which a continuous phase and a dispersed phase containing an acrylic polymer (B) are formed, wherein the acrylic polymer (B) constitutes a monomer unit of the acrylic polymer (B). As the polymerizable monomer (b), at least a (meth) acrylic acid alkyl ester monomer (b1) having an alkyl group having 1 to 4 carbon atoms, and an alkyl (meth) acrylate having an alkyl group having 5 to 20 carbon atoms. It contains an ester monomer (b2), and the blending ratio (b1 / b2) (mass ratio) of the monomer (b1) and the monomer (b2) is 25/75 to 85/15 And features.

  The pressure-sensitive adhesive layer of the present invention preferably has a blending ratio (A / B) (mass ratio) of the rubber polymer (A) to the acrylic polymer (B) of 3/100 to 150/100.

  In the pressure-sensitive adhesive layer of the present invention, the tackifier resin (C) is preferably contained in the continuous phase more than the dispersed phase.

  In the pressure-sensitive adhesive layer of the present invention, the rubber polymer (A) is preferably a saturated styrene block copolymer.

  In the pressure-sensitive adhesive layer of the present invention, the acrylic polymer (B) further contains a nitrogen atom-containing vinyl monomer and / or a carboxyl group-containing vinyl monomer as the polymerizable monomer (b) constituting the monomer unit. It is preferable to do.

  In the pressure-sensitive adhesive layer of the present invention, the acrylic polymer (B) is preferably obtained by polymerizing the polymerizable monomer (b) with radiation energy.

  The pressure-sensitive adhesive sheet of the present invention preferably has the pressure-sensitive adhesive layer.

  The method for producing the pressure-sensitive adhesive layer of the present invention is a method for producing the pressure-sensitive adhesive layer, wherein the rubber-based polymer (A) and the polymerizable monomer (b) constituting the monomer unit of the acrylic-based polymer (B), And the step of preparing the pressure-sensitive adhesive composition by mixing the hydrogenated tackifying resin (C), and polymerizing the pressure-sensitive adhesive composition with radiation energy to thereby convert the rubber-based polymer (A). And a step of preparing a pressure-sensitive adhesive layer forming a dispersed phase containing the continuous phase and the acrylic polymer (B).

  According to the present invention, a pressure-sensitive adhesive layer excellent in adhesive properties such as adhesion to a low surface energy adherend, retention (cohesive force), and repulsion resistance, a pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer, and the pressure-sensitive adhesive A method of manufacturing the layer can be provided and is useful.

It is a transmission electron microscope (TEM) photograph (magnification: 12000 times) of the adhesive layer formed from two components which are incompatible. It is a transmission electron microscope (TEM) photograph (magnification: 12000 times) of the adhesive layer concerning this embodiment. It is a schematic diagram which shows the morphology of the adhesive layer which concerns on this embodiment.

  Normally, when a rubber polymer (rubber component) having a specific function is added to an acrylic polymer (acrylic component), the compatibility of both components is insufficient. The acrylic phase mainly composed of components and the rubber phase mainly composed of rubber components form a so-called sea-island structure. As such a structure, for example, as shown in FIG. 1, a rubber phase (dispersed phase) 1 forms an island phase and an acrylic phase (continuous phase) 2 forms a sea phase. By using (TEM photograph), the pressure-sensitive adhesive layer 10 can be visually observed. The pressure-sensitive adhesive layer having such a structure cannot fully exhibit its function even though a rubber component having a specific function is blended. On the other hand, when a large amount of rubber component is blended, the compatibility is improved. In addition to the inferior results, the economy is also inferior and has problems.

  On the other hand, the pressure-sensitive adhesive layer 10 according to the present embodiment contains a rubber-based polymer (A), an acrylic polymer (B) composed of specific monomer units, and a hydrogenated tackifying resin (C). And having a dense phase separation structure in which a continuous phase (sea phase) 20 containing the rubber polymer (A) and a dispersed phase (island phase) 30 containing the acrylic polymer (B) are formed. Is possible. As such a structure, for example, as shown in FIG. 2 and FIG. 3 (corresponding to a schematic diagram showing an enlarged structure in FIG. 2), the rubber phase (continuous phase) is reversed, as shown in FIG. ) 20 forms a continuous phase (sea phase) and acrylic phase (dispersed phase) 10 forms a dispersed phase (island phase) by using a transmission electron microscope (TEM photograph). The agent layer 10 can be observed. The pressure-sensitive adhesive layer having such a structure has a structure in which a rubber component having a specific function looks like a dense network (continuous phase, sea phase), and mainly contains an acrylic component in the network. The specific (desired) function of the rubber component is fully exerted due to the structure (dispersed phase, island phase), and the characteristics of both the acrylic component and the rubber component can be obtained by adding a small amount of the rubber component. Can be used and is useful. Although the details of the reason for this structure are not clear, the polymerizable monomer (b), which is a precursor of the acrylic polymer (B) that is poorly compatible with the rubber polymer (A), is polymerized and cured. In order to reduce the contact area with the rubber polymer (A) in the process, the acrylic polymer (B) chain (and comprising the polymerizable monomer (b)) rich in fluidity, The coalescence (aggregation) is repeated, and finally the island-like phase (island phase, dispersed phase) (and the rubber-based polymer (A) formed from the acrylic polymer (B) having poor fluidity It is presumed that this is because a solid phase (sea phase, continuous phase)) is formed and immobilized.

  Hereinafter, the raw material constituting the pressure-sensitive adhesive composition used when the pressure-sensitive adhesive layer of the present invention is manufactured, the pressure-sensitive adhesive layer, the pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer, and the method for producing the pressure-sensitive adhesive layer are described in detail. Explained.

[Rubber polymer (A) (component (A))]
The pressure-sensitive adhesive layer of the present invention is characterized by containing a rubber-based polymer (A) as an essential component and forming a continuous phase containing the rubber-based polymer (A). According to the configuration of the present invention, even when the rubber-based polymer (A) has a lower blending ratio than the acrylic polymer (B) described later, a normal rubber-based polymer and an acrylic polymer are blended. Like the resulting adhesive (layer) (see FIG. 1), the rubber-based polymer can form a continuous phase (sea phase) without mainly forming a dispersed phase (island phase) (FIGS. 2 and 2). 3), that is, a dense phase separation structure can be formed, and an excellent adhesive property can be exhibited even on an adherend having a low surface energy, which is useful.

  If the said rubber-type polymer (A) is normally used in the adhesive field | area, it can be used without a restriction | limiting in particular. By using the rubber-based polymer (A), it is possible to improve adhesion characteristics to an adherend (for example, polyolefin) having a low surface energy, which is useful. Examples of the rubber-based polymer (A) include copolymers such as polybutadiene, polyisoprene, polyisobutylene, polystyrene-butadiene-styrene, polystyrene-isoprene-styrene, polystyrene-isobutylene-styrene, polystyrene-vinylpolyisoprene-styrene, polystyrene- Styrene-based triblock copolymers such as vinyl polyisoprene-ethylenepropylene-styrene, styrene-based diblock copolymers such as polystyrene-butadiene, polystyrene-isoprene, polystyrene-isobutylene, polystyrene-vinylpolyisoprene, polystyrene-vinylpolyisoprene-ethylenepropylene, Olefin copolymers such as polyethylene propylene, polyethylene butene and polypropylene butene , Polystyrene-ethylenebutylene-styrene, polystyrene-ethylene-ethylenepropylene-styrene, polystyrene-ethylenepropylene-styrene, polystyrene-butadiene-butylene-styrene, polystyrene-hydrogenated vinylpolyisoprene-styrene, polystyrene-hydrogenated vinylpolyisoprene- Partially hydrogenated or fully hydrogenated styrene triblock copolymers such as ethylene propylene-styrene, polystyrene-ethylene butylene, polystyrene-ethylene-ethylene propylene, polystyrene-ethylene propylene, polystyrene-butadiene-butylene, polystyrene-hydrogenated vinyl poly Partially hydrogenated or fully hydrogenated styrene diesters such as isoprene, polystyrene-hydrogenated vinylpolyisoprene-ethylenepropylene, etc. It can be used various rubber polymers such as rock copolymer. Among them, partially hydrogenated or fully hydrogenated, so-called saturated styrene triblock copolymer or diblock copolymer (saturated styrene block copolymer), polyisobutylene, polystyrene-isobutylene-styrene, in terms of weather resistance, etc. In addition, it is preferable to use a copolymer such as polystyrene-isobutylene, and in order to obtain cohesive strength of the copolymer, a partially hydrogenated type or a fully hydrogenated type, so-called saturated styrene triblock copolymer, polystyrene-isobutylene-styrene, etc. The styrenic triblock copolymer can be suitably used.

  When the rubber-based polymer (A) is a copolymer having polystyrene blocks, the proportion of polystyrene blocks in the copolymer (styrene (St) content) is preferably 2 to 80% by mass, and more preferably 3 to 75% by mass. %, And more preferably 5 to 65% by mass. When the styrene (St) content exceeds 80% by mass, the polymer is difficult to flow, wetness to the adherend becomes insufficient, and adhesive properties may be deteriorated. On the other hand, if the styrene (St) content is less than 2% by mass, the intended cohesive force may not be sufficiently obtained.

[Acrylic polymer (B) (component (B))]
The pressure-sensitive adhesive layer of the present invention contains an acrylic polymer (B) as an essential component, and a dispersed phase containing the acrylic polymer (B) is formed. According to the configuration of the present invention, the rubber-based polymer (A) described above is blended with a normal rubber-based polymer and an acrylic polymer, even if the blending ratio is lower than that of the acrylic polymer (B). Like the resulting adhesive (layer) (see FIG. 1), the rubber-based polymer (A) can form a continuous phase (sea phase) without forming a dispersed phase (island phase) (FIG. 2). 3), a dense phase separation structure can be formed, and an excellent adhesion characteristic can be exhibited even on an adherend having a low surface energy, which is useful.

  The acrylic polymer (B) is a (meth) acrylic acid alkyl ester monomer having at least an alkyl group having 1 to 4 carbon atoms as the polymerizable monomer (b) constituting the monomer unit of the acrylic polymer (B). (B1) and a (meth) acrylic acid alkyl ester monomer (b2) having an alkyl group having 5 to 20 carbon atoms, and a blending ratio (b1 / b2) of the monomer (b1) and the monomer (b2) (Mass ratio) is 25/75 to 85/15. As the polymerizable monomer (b), the monomer (b1) and the monomer (b2) which are (meth) acrylic acid alkyl ester monomers (groups) having different carbon numbers, that is, (meth) acrylic acid alkyl ester monomers having different polarities. By using (Group) together as a main component, it becomes easier to balance the appropriate compatibility with the rubber-based polymer (A) and the adhesive properties when the pressure-sensitive adhesive layer is formed. . The alkyl group may be linear or branched. The “main component” means, for example, the monomer unit (component) having the largest content in the monomer unit (component) constituting the acrylic polymer (B), preferably 30% by mass. More than 40% by mass, more preferably more than 50% by mass. The same applies hereinafter.

  The proportion of the (meth) acrylic acid alkyl ester having a linear or branched alkyl group having 1 to 20 carbon atoms is 50 masses based on the total amount of monomer units for preparing the acrylic polymer (B). It is a more preferable aspect to contain more than%, 60-99.9 mass% is still more preferable, 70-99 mass% is especially preferable, 80-98 mass% is the most preferable. Within the above range, the adhesive properties (particularly adhesive strength and wettability to the adherend) are excellent, which is a preferred embodiment.

[C1-C4 (meth) acrylic acid alkyl ester monomer (b1)]
Examples of the (meth) acrylic acid alkyl ester having a C 1-4 alkyl group include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, Examples include butyl (meth) acrylate, isobutyl (meth) acrylate, s-butyl (meth) acrylate, and t-butyl (meth) acrylate. Of these, butyl (meth) acrylate can be preferably used. In addition, (meth) acrylic acid alkyl ester means acrylic acid alkyl ester and / or methacrylic acid alkyl ester, and “(meth)...” Has the same meaning. In addition, the said monomer can be used individually or in the structure which combined 2 or more types.

[C5-20 (meth) acrylic acid alkyl ester monomer (b2)]
Examples of the (meth) acrylic acid alkyl ester having an alkyl group having 5 to 18 carbon atoms include pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, Octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate Undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, cetyl (meth) acrylate, Isomethyl (meth) acrylate, (meth) acrylic Le acid heptadecyl, (meth) acrylate, octadecyl (meth) isostearyl acrylate, (meth) acrylate, nonadecyl and (meth) eicosyl acrylate. Of these, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, and isononyl (meth) acrylate can be suitably used. The (meth) acrylic acid alkyl ester refers to an acrylic acid alkyl ester and / or a methacrylic acid alkyl ester, and “(meth)...” Has the same meaning. Moreover, the said monomer can be used as a structure independent or 2 types or more combined.

  The blending ratio (b1 / b2) (mass ratio) of the monomer (b1) and the monomer (b2) constituting the monomer unit of the acrylic polymer (B) is 25/75 to 85/15, preferably 35/65 to 85/15, more preferably 45/55 to 85/15. By blending the polymerizable monomer (b) at a blending ratio (b1 / b2) (mass ratio) of the monomer (b1) and the monomer (b2) which are the monomer (group) having different carbon numbers, that is, Is a combination of the (meth) acrylic acid alkyl ester monomer (group) having different polarities as a main component in combination with the rubber-based polymer (A), and an adhesive layer when an adhesive layer is formed. It becomes easier to balance the characteristics, which is a preferred mode. In addition, when the blending ratio of the monomer (b1) (when the total amount of (b1) and (b2) is 100) is less than 25, it may be difficult to balance the adhesive properties of the obtained pressure-sensitive adhesive layer. is there. On the other hand, when the blending ratio of the monomer (b2) (when the total amount of (b1) and (b2) is 100) is less than 15, the polarity of the polymerizable monomer (b) as a whole increases, and the rubber system The compatibility between the polymer and the polymerizable monomer (b) becomes poor, and the mixed (blended) product may become a gel or it may be difficult to form a pressure-sensitive adhesive layer having the target phase separation structure, which is not preferable.

  The acrylic polymer (B) is a monomer component that can be copolymerized with the (meth) acrylic acid alkyl ester as necessary for the purpose of modifying cohesive strength, heat resistance, crosslinkability, and the like. (Other (co) polymerizable monomer (b)) may be included. Among these, as the other (co) polymerizable monomer (b), a monomer having a polar group can be preferably used.

Specific examples of the other (co) polymerizable monomer (b) include
Carboxyl group-containing monomers such as acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid;
Hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, hydroxyhexyl (meth) acrylate, hydroxyoctyl (meth) acrylate, hydroxydecyl (meth) acrylate, (meta ) Hydroxyl-containing monomers such as hydroxyalkyl (meth) acrylates such as hydroxylauryl acrylate and (4-hydroxymethylcyclohexyl) methyl methacrylate;
Acid anhydride group-containing monomers such as maleic anhydride and itaconic anhydride;
Sulphonic acid groups such as styrene sulfonic acid, allyl sulfonic acid, 2- (meth) acrylamide-2-methylpropane sulfonic acid, (meth) acrylamide propane sulfonic acid, sulfopropyl (meth) acrylate, (meth) acryloyloxynaphthalene sulfonic acid Containing monomers;
Phosphate group-containing monomers such as 2-hydroxyethylacryloyl phosphate;
(Meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N, N-dipropyl (meth) acrylamide, N, N-diisopropyl (meth) acrylamide, N, N-di N, N-dialkyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-isopropyl (meth) such as (n-butyl) (meth) acrylamide, N, N-di (t-butyl) (meth) acrylamide Acrylamide, N-butyl (meth) acrylamide, Nn-butyl (meth) acrylamide, N-methylol (meth) acrylamide, N-ethylol (meth) acrylamide, N-methylolpropane (meth) acrylamide, N-methoxymethyl ( (Meth) acrylamide, N-methoxyethyl (meta) Acrylamide, N- butoxymethyl (meth) acrylamide, N- acryloyl morpholine, etc. (N- substituted) amide monomers;
Succinimide monomers such as N- (meth) acryloyloxymethylenesuccinimide, N- (meth) acryloyl-6-oxyhexamethylenesuccinimide, N- (meth) acryloyl-8-oxyhexamethylenesuccinimide;
Maleimide monomers such as N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, N-phenylmaleimide;
Itaconimides such as N-methylitaconimide, N-ethylitaconimide, N-butylitaconimide, N-octylitaconimide, N-2-ethylhexylitaconimide, N-cyclohexylitaconimide, N-laurylitaconimide System monomers;
N-vinyl-2-pyrrolidone, N-methylvinylpyrrolidone, N-vinylpyridine, N-vinylpiperidone, N-vinylpyrimidine, N-vinylpiperazine, N-vinylpyrazine, N-vinylpyrrole, N-vinylimidazole, N- Vinyloxazole, N- (meth) acryloyl-2-pyrrolidone, N- (meth) acryloylpiperidine, N- (meth) acryloylpyrrolidine, N-vinylmorpholine, N-vinyl-2-piperidone, N-vinyl-3-morpholinone N-vinyl-2-caprolactam, N-vinyl-1,3-oxazin-2-one, N-vinyl-3,5-morpholinedione, N-vinylpyrazole, N-vinylisoxazole, N-vinylthiazole, Contains nitrogen such as N-vinylisothiazole and N-vinylpyridazine Ring-based monomer;
N-vinylcarboxylic acid amides;
Lactam monomers such as N-vinylcaprolactam;
Cyanoacrylate monomers such as acrylonitrile and methacrylonitrile;
(Meth) acrylic such as aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, and t-butylaminoethyl (meth) acrylate Acid aminoalkyl monomers;
(Meth) acrylic acid alkoxyalkyl monomers such as (meth) acrylic acid methoxyethyl, (meth) acrylic acid ethoxyethyl, (meth) acrylic acid propoxyethyl, (meth) acrylic acid butoxyethyl, (meth) acrylic acid ethoxypropyl ;
Styrene monomers such as styrene and α-methylstyrene;
Epoxy group-containing acrylic monomers such as (meth) glycidyl acrylate;
Glycol-based acrylic ester monomers such as (meth) acrylic acid polyethylene glycol, (meth) acrylic acid polypropylene glycol, (meth) acrylic acid methoxyethylene glycol, (meth) acrylic acid methoxypolypropylene glycol;
(Meth) acrylic acid tetrahydrofurfuryl, fluorine atom-containing (meth) acrylate, silicone (meth) acrylate and other heterocyclic rings, halogen atoms, silicon atoms and the like, acrylic ester monomers;
Olefin monomers such as isoprene, butadiene, isobutylene;
Vinyl ether monomers such as methyl vinyl ether and ethyl vinyl ether;
Vinyl esters such as vinyl acetate and vinyl propionate;
Aromatic vinyl compounds such as vinyltoluene and styrene;
Olefins or dienes such as ethylene, butadiene, isoprene, isobutylene;
Vinyl ethers such as vinyl alkyl ethers;
Vinyl chloride;
Sulfonic acid group-containing monomers such as sodium vinyl sulfonate;
Imide group-containing monomers such as cyclohexylmaleimide and isopropylmaleimide;
Isocyanate group-containing monomers such as 2-isocyanatoethyl (meth) acrylate;
(Meth) acrylic acid ester having an alicyclic hydrocarbon group such as cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate;
(Meth) acrylic acid ester having an aromatic hydrocarbon group such as phenyl (meth) acrylate;
(Meth) acrylic acid ester obtained from terpene compound derivative alcohol;
Etc. In addition, these polymerizable monomers (b) can be used individually or in combination of 2 or more types.

  The content of the other (co) polymerizable monomer (b) is not particularly limited, but usually the other (co-polymerizable monomer) is used with respect to the total amount of monomer units (100% by mass) for preparing the acrylic polymer. ) It is preferable to contain 0.1-40 mass% of polymerizable monomers (b), More preferably, it is 0.5-30 mass%, More preferably, it is 1-20 mass%. By containing 0.1% by mass or more of the other (co) polymerizable monomer (b), it is possible to keep the pressure-sensitive adhesive (layer) retainability and repulsion resistance. Further, by setting the content of the polymerizable monomer (b) to 40% by mass or less, it is possible to prevent the cohesive force from becoming too high, improve the tack feeling at room temperature (25 ° C.), and increase the adhesive strength. can do.

［式（１）中、Ｒ^１は２価の有機基である］ Moreover, among the monomer units (components) described above, the nitrogen monomer-containing vinyl monomer and / or the carboxyl group-containing vinyl monomer are included as the polymerizable monomer (b) constituting the monomer unit of the acrylic polymer (B). It is preferable to do. By containing the monomer, the pressure-sensitive adhesive (layer) can have an appropriate cohesive force, and excellent adhesive properties can be obtained, which is a preferred embodiment. Examples of the nitrogen atom-containing vinyl monomer include (meth) acrylamides and N-vinyl cyclic amides represented by the following general formula (1). Examples of the carboxyl group-containing monomer include acrylic acid, methacrylic acid, carboxyethyl acrylate, and carboxypentyl acrylate. Among them, N- vinyl-2-pyrrolidone (R ¹ has a propylene group is a divalent organic group) and can be preferably used acrylic acid.

[In Formula (1), R ¹ is a divalent organic group]

The content of the (co) polymerizable monomer (b) represented by the general formula (1) is not particularly limited, but is usually based on the total amount of monomer units for preparing the acrylic polymer (B). It is preferable to contain 0.1-40 mass%, More preferably, it is 0.5-30 mass%, More preferably, it is 1-20 mass%. Within the above range,
The pressure-sensitive adhesive layer has excellent adhesive properties and is a preferred embodiment.

  In addition, the acrylic polymer (B) may contain a polyfunctional monomer as a monomer unit (polymerizable monomer (b)) as necessary to adjust the cohesive force of the pressure-sensitive adhesive layer. .

  Examples of the polyfunctional monomer include (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, pentaerythritol di (meth) acrylate, penta Erythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,2-ethylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,12-dodecanediol di (meth) Acrylate, trimethylolpropane tri (meth) acrylate, tetramethylolmethane tri (meth) acrylate, allyl (meth) acrylate, vinyl (meth) acrylate, divinylbenzene, epoxy acrylate Polyester acrylate, urethane acrylate, butyl di (meth) acrylate, hexyl di (meth) acrylate. Among these, trimethylolpropane tri (meth) acrylate, hexanediol di (meth) acrylate, and dipentaerythritol hexa (meth) acrylate can be preferably used. A polyfunctional monomer can be used individually or in combination of 2 or more types.

  As content of the said polyfunctional monomer, although it changes with the molecular weight, the number of functional groups, etc., 0.01-3 mass% with respect to the monomer unit (component) whole quantity for preparing an acryl-type polymer (B), Preferably it is 0.02-2 mass%, More preferably, it adds so that it may become 0.03-1 mass%. When content of the said polyfunctional monomer exceeds 3 mass%, the cohesive force of an adhesive layer will become high too much, and adhesive force may fall. On the other hand, if it is less than 0.01% by mass, the cohesive force of the pressure-sensitive adhesive layer may be reduced.

  The method for synthesizing the acrylic polymer (B) is not particularly limited, and as a synthesis method for (meth) acrylic polymers such as solution polymerization, emulsion polymerization, bulk polymerization, suspension polymerization, and radiation curing polymerization, Various polymerization methods used can be applied.

<Polymerization initiator>
In preparing the acrylic polymer (B), the polymerizable monomer (b) is preferably obtained by polymerization with radiation energy (for example, irradiation with heat, ultraviolet rays, etc.). During the polymerization, acrylic polymers can be easily prepared using a polymerization reaction by radiation energy (for example, heat or ultraviolet light) using a polymerization initiator such as a thermal polymerization initiator or a photopolymerization initiator (photoinitiator). This is a preferred embodiment. In particular, a photopolymerization initiator can be preferably used because of the advantage that the polymerization time can be shortened. A polymerization initiator can be used individually or in combination of 2 or more types.

  Examples of the thermal polymerization initiator include azo polymerization initiators (for example, 2,2′-azobisisobutyronitrile, 2,2′-azobis-2-methylbutyronitrile, 2,2′-azobis). (2-methylpropionic acid) dimethyl, 4,4′-azobis-4-cyanovaleric acid, azobisisovaleronitrile, 2,2′-azobis (2-amidinopropane) dihydrochloride, 2,2′-azobis [ 2- (5-methyl-2-imidazolin-2-yl) propane] dihydrochloride, 2,2′-azobis (2-methylpropionamidine) disulfate, 2,2′-azobis (N, N′-di) Methyleneisobutylamidine) dihydrochloride, etc.); peroxide polymerization initiators (for example, dibenzoyl peroxide, t-butylpermaleate, lauro peroxide) Le etc.); redox polymerization initiators, and the like.

  Although it does not restrict | limit especially as content of the said thermal-polymerization initiator, For example, with respect to 100 mass parts of monomer units (polymerizable monomer (b)) whole quantity which prepares the said acrylic polymer (B), 0.01- 5 mass parts is preferable, More preferably, it is 0.05-3 mass parts.

  The photopolymerization initiator is not particularly limited. For example, benzoin ether photopolymerization initiator, acetophenone photopolymerization initiator, α-ketol photopolymerization initiator, aromatic sulfonyl chloride photopolymerization initiator, photo Active oxime photopolymerization initiator, benzoin photopolymerization initiator, benzyl photopolymerization initiator, benzophenone photopolymerization initiator, ketal photopolymerization initiator, thioxanthone photopolymerization initiator, acylphosphine oxide photopolymerization initiator An initiator or the like can be used.

  Specifically, examples of the benzoin ether photopolymerization initiator include benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dimethoxy-1,2-diphenylethane- 1-one [trade name: Irgacure 651, manufactured by BASF Corporation], anisole methyl ether and the like can be mentioned. Examples of the acetophenone photopolymerization initiator include 1-hydroxycyclohexyl phenyl ketone [trade name: Irgacure 184, manufactured by BASF Corp.], 4-phenoxydichloroacetophenone, 4-t-butyl-dichloroacetophenone, 1- [4- ( 2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one [trade name: Irgacure 2959, manufactured by BASF Corp.], 2-hydroxy-2-methyl-1-phenyl-propane- 1-one [trade name: Darocur 1173, manufactured by BASF Corporation], methoxyacetophenone, and the like can be given. Examples of the α-ketol photopolymerization initiator include 2-methyl-2-hydroxypropiophenone, 1- [4- (2-hydroxyethyl) -phenyl] -2-hydroxy-2-methylpropane-1- ON etc. are mentioned. Examples of the aromatic sulfonyl chloride-based photopolymerization initiator include 2-naphthalene sulfonyl chloride. Examples of the photoactive oxime photopolymerization initiator include 1-phenyl-1,1-propanedione-2- (o-ethoxycarbonyl) -oxime.

  The benzoin photopolymerization initiator includes, for example, benzoin. Examples of the benzyl photopolymerization initiator include benzyl and the like. Examples of the benzophenone-based photopolymerization initiator include benzophenone, benzoylbenzoic acid, 3,3′-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, α-hydroxycyclohexyl phenyl ketone, and the like. Examples of the ketal photopolymerization initiator include benzyl dimethyl ketal. Examples of the thioxanthone photopolymerization initiator include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, dodecylthioxanthone and the like are included.

  Examples of the acylphosphine photopolymerization initiator include bis (2,6-dimethoxybenzoyl) phenylphosphine oxide, bis (2,6-dimethoxybenzoyl) (2,4,4-trimethylpentyl) phosphine oxide, bis ( 2,6-dimethoxybenzoyl) -n-butylphosphine oxide, bis (2,6-dimethoxybenzoyl)-(2-methylpropan-1-yl) phosphine oxide, bis (2,6-dimethoxybenzoyl)-(1- Methylpropan-1-yl) phosphine oxide, bis (2,6-dimethoxybenzoyl) -t-butylphosphine oxide, bis (2,6-dimethoxybenzoyl) cyclohexylphosphine oxide, bis (2,6-dimethoxybenzoyl) octylphosphine Oxide, bis (2- Toxibenzoyl) (2-methylpropan-1-yl) phosphine oxide, bis (2-methoxybenzoyl) (1-methylpropan-1-yl) phosphine oxide, bis (2,6-diethoxybenzoyl) (2-methyl Propan-1-yl) phosphine oxide, bis (2,6-diethoxybenzoyl) (1-methylpropan-1-yl) phosphine oxide, bis (2,6-dibutoxybenzoyl) (2-methylpropane-1- Yl) phosphine oxide, bis (2,4-dimethoxybenzoyl) (2-methylpropan-1-yl) phosphine oxide, bis (2,4,6-trimethylbenzoyl) (2,4-dipentoxyphenyl) phosphine oxide Bis (2,6-dimethoxybenzoyl) benzylphosphine oxide, bis 2,6-dimethoxybenzoyl) -2-phenylpropylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2-phenylethylphosphine oxide, bis (2,6-dimethoxybenzoyl) benzylphosphine oxide, bis (2,6 -Dimethoxybenzoyl) -2-phenylpropylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2-phenylethylphosphine oxide, 2,6-dimethoxybenzoylbenzylbutylphosphine oxide, 2,6-dimethoxybenzoylbenzyloctylphosphine oxide Bis (2,4,6-trimethylbenzoyl) -2,5-diisopropylphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -2-methylphenylphosphine oxide, bis (2 4,6-trimethylbenzoyl) -4-methylphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -2,5-diethylphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -2, 3,5,6-tetramethylphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -2,4-di-n-butoxyphenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, bis (2,4,6-trimethylbenzoyl) isobutylphosphine oxide, 2,6-dimethoxybenzoyl-2,4,6-trimethyl Benzoyl-n-butylphosphine oxide, bis (2,4 6-trimethylbenzoyl) phenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -2,4-dibutoxyphenylphosphine oxide, 1,10-bis [bis (2,4,6-trimethylbenzoyl) phosphine oxide Decane, tri (2-methylbenzoyl) phosphine oxide, and the like.

  Although content in particular of the said photoinitiator is not restrict | limited, For example, 0.01-5 mass with respect to 100 mass parts of monomer units (polymerizable monomer (b)) whole quantity which prepares an acrylic polymer (B). Part is preferable, and 0.05 to 3 parts by mass is more preferable. When the content is less than 0.01 parts by mass, the polymerization reaction may become insufficient. Moreover, when the said content exceeds 5 mass parts, the molecular weight of a polymer may become small too much. And thereby, the cohesive force of the adhesive layer formed becomes low, and adhesive characteristics, such as holding | maintenance property and repulsion resistance, may fall.

  Examples of the radiation include ultraviolet (UV), laser beam, α-ray, β-ray, γ-ray, X-ray, and electron beam. Ultraviolet rays are preferable from the viewpoints of controllability, ease of handling, and cost. Used for. More preferably, ultraviolet rays having a wavelength of 200 to 400 nm are used. Ultraviolet rays can be irradiated using an appropriate light source such as a high-pressure mercury lamp, a microwave excitation lamp, or a chemical lamp.

  Furthermore, it is also possible to use a photopolymerization initiation assistant such as amines together with the photopolymerization initiator. Examples of the photopolymerization initiation assistant include 2-dimethylaminoethylbenzoate, dimethylaminoacetophenone, p-dimethylaminobenzoic acid ethyl ester, p-dimethylaminobenzoic acid isoamyl ester, and the like. These compounds may be used alone or in combination of two or more. It is preferable to mix 0.05-10 mass parts with respect to 100 mass parts of said polymers (A), and, as for photopolymerization start adjuvant, it is more preferable to mix | blend in the range of 0.1-7 mass parts. Within the above range, it is preferable from the viewpoint of easily controlling the polymerization reaction and obtaining an appropriate molecular weight.

In addition, when the photopolymerization initiator is blended, the pressure-sensitive adhesive composition is directly applied on an adherend (protected body) or after being applied to a predetermined coated body such as a separator. Alternatively, the pressure-sensitive adhesive layer can be obtained by light irradiation after coating on one side of the support (base material). Usually, the pressure-sensitive adhesive layer is obtained by irradiating ultraviolet rays having an illuminance of 1 to 200 mW / cm ² at a wavelength of 300 to 400 nm and photopolymerizing them with a light amount of about 200 to 4000 mJ / cm ² .

  The acrylic polymer (B) has a weight average molecular weight (Mw) of, for example, preferably 30,000 to 5,000,000, more preferably 100,000 to 2,000,000, still more preferably 200,000 to 1,000,000. If the weight average molecular weight (Mw) is too smaller than the above range, the cohesive force of the pressure sensitive adhesive (layer) will be insufficient, and if the weight average molecular weight (Mw) is too large than the above range, the flowability of the pressure sensitive adhesive will be low. There are cases where the wetness to the body is insufficient and the adhesive strength (adhesive strength) is lowered.

  The weight average molecular weight (Mw) can be measured in terms of polystyrene by GPC (gel permeation chromatography) method. Specifically, it can be measured on a HPLC 8020 manufactured by Tosoh Corporation using TSKgelGMH-H (20) × 2 columns as a column with a tetrahydrofuran solvent at a flow rate of about 0.5 ml / min.

  In addition, the glass transition temperature (Tg) of the acrylic polymer (B) is less than 0 ° C., preferably less than −10 ° C., more preferably less than −40 ° C., and usually at −80 ° C. or more. is there. When the glass transition temperature (Tg) of the acrylic polymer (B) is 0 ° C. or higher, the polymer is difficult to flow, the wetting to the adherend becomes insufficient, and the adhesive strength (adhesive strength) may decrease. is there.

_{1 / Tg = W 1 / Tg} 1 + W 2 / Tg 2 + ··· + Wn / Tg n (2)
[In the formula (2), Tg is the glass transition temperature (unit: K) of the copolymer, and Tg _i (i = 1, 2,... N) is the glass transition when the monomer i forms a homopolymer. Temperature (unit: K), W _i (i = 1, 2,... N) represents a mass fraction of all monomer components of monomer i. ]
Further, the glass transition temperature Tgi of the monomer i is a nominal value described in the literature (for example, polymer handbook, adhesive hand log, etc.).

  The pressure-sensitive adhesive layer of the present invention has a blending ratio (A / B) (mass ratio) of the rubber-based polymer (A) to the acrylic polymer (B) of 3/100 to 150/100. It is preferably 5/100 to 100/100, more preferably 7/100 to 70/100, and particularly preferably 10/100 to 50/100. Within the above range, it becomes easier to balance the appropriate compatibility and the adhesive properties when the pressure-sensitive adhesive layer is formed, which is a preferred embodiment. Further, as shown in FIGS. 2 and 3, the pressure-sensitive adhesive (layer) can form a dense phase separation structure (sea-island structure), and adheres to and adheres to a low surface energy adherend (cohesive force). ), A pressure-sensitive adhesive layer excellent in adhesive properties such as resilience, a pressure-sensitive adhesive sheet having the pressure-sensitive adhesive layer, and a method for producing the pressure-sensitive adhesive layer can be provided and useful.

[Hydrogenated type tackifying resin (C) (component (C))]
The pressure-sensitive adhesive layer of the present invention contains the hydrogenated tackifier resin (C) as an essential component, and the tackifier resin (C) is preferably contained in the continuous phase more than the dispersed phase. . By containing the tackifying resin (C), sufficient adhesive properties can be obtained for a low surface energy (low polarity) adherend such as polyolefin, which is a preferred embodiment. On the other hand, when a non-hydrogenated type (no hydrogenation, no hydrogenation) tackifying resin is contained, the detailed reason is not clear, but the polymerizable monomer (b) which is a precursor of the acrylic polymer (B) However, in the process of polymerization and curing by radiation irradiation, radicals generated by radiation irradiation act on unsaturated bonds in tackifying resins that are not hydrogenated, and the molecular weight of the acrylic polymer (B) is remarkably high. To a continuous phase in which the acrylic polymer (B) and the non-hydrogenated tackifier resin are bonded by the action of radicals, and the tackifier resin contains the rubber polymer (A) (as a main component). It is presumed that the uneven distribution is less likely to occur, and there is a possibility that sufficient adhesion characteristics cannot be obtained for adherends of low surface energy (low polarity) such as polyolefin. Although the detailed reason why the hydrogenated tackifying resin (C) is contained in the continuous phase is not clear, the solubility parameter (SP) value of the tackifying resin (C) It is presumed that the SP value of the polymer (A) is close and the compatibility between the hydrogenated tackifying resin (C) and the rubber-based polymer (A) is high.

The SP value is a solubility parameter (SP) value of the polymer. As a method for specifying the SP value, a method using a conventionally known estimation formula such as a Fedors formula, a Small formula, a Vam Krebelen formula, or an experiment The method of actually measuring by is mentioned. Among these, it is preferable to use the Fedors equation for obtaining a simple and reasonable estimate. The Fedors equation is as shown in the following general formula (3).
SP value ((cal / cm ³ ) ^1/2 ) = (Σei / Σvi) ^0.5 formula (3)
Here, ei represents the evaporation energy of each atomic group of the compound (monomer) constituting the polymer, and vi represents the molar volume of each atomic group of the compound (monomer) constituting the polymer.

  The tackifying resin (C) can be used without particular limitation as long as it is usually used in the adhesive field. For example, petroleum resins, terpene resins, coumarone / indene resins, styrene resins, alkylphenols. It can be selected from derivatives obtained by hydrogenation of tackifying resins such as a xylene-based resin and a xylene-based resin. More specifically, the hydrogenated petroleum resin can be selected from aromatic, dicyclopentadiene, aliphatic, aromatic-dicyclopentadiene copolymer. The hydrogenated terpene resin can be selected from terpene resins, pinene resins, terpene phenol resins, aromatic terpene resins, and the like. Among these, it is particularly preferable to use a hydrogenated petroleum resin or a hydrogenated terpene resin.

  The softening point (ring and ball method) of the tackifying resin (C) is preferably 80 to 200 ° C, more preferably 90 to 180 ° C. When the softening point of the tackifying resin (C) is in the above range, it is possible to achieve both a high balance of tackiness and an excellent balance of properties such as excellent retention and repulsion resistance.

  The content of the tackifier resin (C) is preferably 3 to 150 parts by weight, more preferably 7 to 100 parts by weight, and still more preferably 100 parts by weight of the acrylic polymer (B). Is 11 to 70 parts by mass. When the content of the tackifying resin (C) is within the above range, the adhesive properties of the pressure-sensitive adhesive sheet can be maintained in a well-balanced manner.

  Moreover, when preparing the adhesive composition used when forming the adhesive layer of this invention, a silane coupling agent is used in order to improve the adhesiveness and durability of an adhesive layer (adhesive sheet). Can do. The silane coupling agent is not particularly limited. Examples of the silane coupling agent include vinyl group-containing silane coupling agents such as vinyltrichlorosilane, vinyltris (β-methoxyethoxy) silane, vinyltriethoxysilane, and vinyltrimethoxysilane, and p-styryltrimethoxysilane. (Meth) acryloyl group-containing silane coupling agent such as styryl group-containing silane coupling agent, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, γ-acryloxypropyltrimethoxysilane, β- ( 3,4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane and other epoxy group-containing silane coupling agents, N-β (aminoethyl) γ- Amino group-containing silane coupling agents such as minopropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane, γ-aminopropyltriethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, Examples include silane coupling agents such as γ-chloropropyltrimethoxysilane, γ-mercaptopropylmethyldimethoxysilane, bis (triethoxysilylpropyl) tetrasulfide, and γ-isocyanatopropyltrimethoxysilane. A silane coupling agent having an epoxy group is preferable, and γ-glycidoxypropyltrimethoxysilane is more preferable. The silane coupling agents may be used alone or in combination of two or more.

  The content of the silane coupling agent is preferably 0.01 to 10 parts by mass, more preferably 0.02 to 5 parts by mass with respect to 100 parts by mass of the acrylic polymer (B). More preferably, it is 0.05-2 mass parts. By using it within the above range, it is possible to improve the retention (cohesive force) and durability more reliably.

  The pressure-sensitive adhesive composition according to this embodiment contains the rubber-based polymer (A), the acrylic polymer (B), and the hydrogenated tackifying resin (C) as essential components, and in the field of pressure-sensitive adhesives. Various general additives can be contained as optional components. Examples of such optional components include plasticizers, softeners, fillers, colorants (pigments, dyes, etc.), antioxidants, leveling agents, stabilizers, preservatives, antistatic agents and the like. Conventionally known additives can be used as such additives.

<Crosslinking agent>
In order to adjust the cohesive strength of the pressure-sensitive adhesive layer of the present invention, the pressure-sensitive adhesive composition may contain a crosslinking agent. As the cross-linking agent, a cross-linking agent generally used in the pressure-sensitive adhesive field can be used. For example, an isocyanate cross-linking agent, an epoxy cross-linking agent, a silicone cross-linking agent, an oxazoline cross-linking agent, an aziridine cross-linking agent, or a silane type. Crosslinking agents, melamine crosslinking agents (alkyl etherified melamine crosslinking agents, etc.), metal chelate crosslinking agents and the like can be mentioned. Moreover, it is also possible to use the said polyfunctional monomer which can be used as a monomer unit (component) of the said acrylic polymer (B) mentioned above as a crosslinking agent. In particular, an isocyanate-based crosslinking agent, an epoxy-based crosslinking agent, and a metal chelate-based crosslinking agent can be preferably used. These compounds may be used alone or in combination of two or more.

  Examples of the isocyanate-based crosslinking agent (isocyanate compound) include lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate, cycloaliphatic isocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate, and isophorone diisocyanate. , Aromatic isocyanates such as 2,4-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate, trimethylolpropane / tolylene diisocyanate trimer adduct (trade name Coronate L, Nippon Polyurethane Manufactured by Kogyo Co., Ltd.), trimethylolpropane / hexamethylene diisocyanate trimer adduct (trade name Coronate HL, manufactured by Nippon Polyurethane Industry Co., Ltd.), hexamethylene dii Isocyanate adducts such as isocyanurate of socyanate (trade name: Coronate HX, manufactured by Nippon Polyurethane Industry Co., Ltd.). Alternatively, a compound having at least one isocyanate group and one or more unsaturated bonds in one molecule, specifically, 2-isocyanatoethyl (meth) acrylate or the like may be used as an isocyanate-based crosslinking agent. Can do.

  Examples of the epoxy crosslinking agent (epoxy compound) include bisphenol A, epichlorohydrin type epoxy resin, ethylene glycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether, glycerin triglycidyl ether, and 1,6-hexanediol. Glycidyl ether, trimethylolpropane triglycidyl ether, diglycidyl aniline, diamine glycidyl amine, N, N, N ′, N′-tetraglycidyl-m-xylenediamine (trade name: TETRAD-X, manufactured by Mitsubishi Gas Chemical Co., Inc.) and 1 , 3-bis (N, N-diglycidylaminomethyl) cyclohexane (trade name: TETRAD-C, manufactured by Mitsubishi Gas Chemical Company, Inc.).

  Examples of the melamine-based crosslinking agent include hexamethylol melamine. Examples of the aziridine-based cross-linking agent (aziridine derivative) include, for example, a commercial product name HDU (manufactured by Mutual Pharmaceutical Co., Ltd.), a product name TAZM (manufactured by Mutual Pharmaceutical Co., Ltd.), and a trade name TAZO (mutual pharmaceutical Co., Ltd.). Manufactured).

  Examples of the metal chelate-based crosslinking agent (metal chelate compound) include aluminum, iron, tin, titanium and nickel as metal components, and acetylene, methyl acetoacetate and ethyl lactate as chelate components.

  The content of the crosslinking agent used in the present invention is not particularly limited, but for example, it is preferably 0.001 to 0.8 parts by mass with respect to 100 parts by mass of the acrylic polymer (B). It is more preferable to contain -0.7 mass part. When the content of the cross-linking agent is less than 0.001 part by mass, the cohesive force of the pressure-sensitive adhesive (layer) decreases, and when the content of the cross-linking agent exceeds 0.8 part by mass, the pressure-sensitive adhesive (layer) The cohesive force is large, the fluidity is lowered, the wetness to the adherend is insufficient, and the adhesive strength (adhesive strength) may be lowered.

  Further, the content of the polyfunctional monomer is appropriately selected depending on the balance with the polymer to be crosslinked, and further depending on the intended use of the pressure-sensitive adhesive layer (pressure-sensitive adhesive sheet). In addition, in order to obtain sufficient heat resistance by the cohesive force of the pressure-sensitive adhesive (layer), it is preferable to blend at 0.001 to 1.0 part by mass with respect to 100 parts by mass of the acrylic polymer (B). . Moreover, it is more preferable to mix | blend at 0.5 mass part or less with respect to 100 mass parts of said acrylic polymers (B) from the point of a softness | flexibility and adhesiveness.

  In addition, when using the said polyfunctional monomer as a crosslinking agent, in order to advance a crosslinking reaction, radiation irradiation can be performed. Examples of the radiation include ultraviolet rays, laser beams, α rays, β rays, γ rays, X rays, and electron beams, but ultraviolet rays are preferably used from the viewpoint of good controllability and handleability and cost. . More preferably, ultraviolet rays having a wavelength of 200 to 400 nm are used. Ultraviolet rays can be irradiated using an appropriate light source such as a high-pressure mercury lamp, a microwave excitation lamp, or a chemical lamp. When ultraviolet rays are used as radiation, the pressure-sensitive adhesive composition includes a photopolymerization initiator (photoinitiator) that can be used in the preparation (polymerization) of the acrylic polymer (B), and a photopolymerization start. Auxiliaries can be similarly blended and added. In addition, when the polyfunctional monomer is used as a crosslinking agent, it can be irradiated with radiation, but as the photopolymerization initiator used in this case, depending on the type of the radiation reactive component, the polymerization reaction may be performed. Any substance that generates radicals or cations by irradiating ultraviolet rays having an appropriate wavelength that can be triggered can be used.

  When using a polyfunctional monomer as a crosslinking agent, the said photoinitiator is normally mix | blended 0.1-10 mass parts with respect to 100 mass parts of said acrylic polymers (B), for example, 0.2 It is preferable to mix in the range of ˜7 parts by mass. Within the above range, it is preferable from the viewpoint of easily controlling the polymerization reaction and obtaining an appropriate molecular weight.

In the case where the photopolymerization initiator is added, the pressure-sensitive adhesive composition is directly applied on an adherend (protected body) or after being applied to a predetermined coated body such as a separator, or Then, after coating on one side of the support (base material), the cross-linking reaction is advanced by light irradiation to obtain a pressure-sensitive adhesive layer. Usually, the pressure-sensitive adhesive layer is obtained by irradiating ultraviolet rays having an illuminance of 1 to 200 mW / cm ² at a wavelength of 300 to 400 nm and photopolymerizing them with a light amount of about 200 to 4000 mJ / cm ² .

  The pressure-sensitive adhesive composition used in the present invention may further contain a crosslinking accelerator. The kind of crosslinking accelerator can be suitably selected according to the kind of crosslinking agent to be used. In the present specification, the crosslinking accelerator refers to a catalyst that increases the speed of the crosslinking reaction by the crosslinking agent. Examples of the crosslinking accelerator include tin (Sn) -containing compounds such as dioctyltin dilaurate, dibutyltin dilaurate, dibutyltin diacetate, dibutyltin diacetylacetonate, tetra-n-butyltin, and trimethyltin hydroxide; N, N , N ′, N′-tetramethylhexanediamine, amines such as triethylamine, and nitrogen (N) -containing compounds such as imidazoles. Of these, Sn-containing compounds are preferred. The amount of the crosslinking accelerator contained in the pressure-sensitive adhesive composition is, for example, about 0.0001 to 1.0 part by mass (preferably 0.001 to 0.5 part by mass) with respect to 100 parts by mass of the acrylic polymer (B). Part).

  Furthermore, the pressure-sensitive adhesive composition may contain a compound that causes keto-enol tautomerism. For example, in a pressure-sensitive adhesive composition containing a cross-linking agent or a pressure-sensitive adhesive composition that can be used by blending a cross-linking agent, an embodiment including a compound that produces the keto-enol tautomerism can be preferably employed. Thereby, the excessive viscosity raise and gelation of an adhesive composition after a crosslinking agent mixing | blending can be suppressed, and the effect of extending the pot life of an adhesive composition may be implement | achieved. When at least an isocyanate compound is used as the crosslinking agent, it is particularly meaningful to contain a compound that causes keto-enol tautomerism. This technique can be preferably applied when, for example, the pressure-sensitive adhesive composition is in an organic solvent solution or a solvent-free form.

  Various β-dicarbonyl compounds can be used as the compound that causes keto-enol tautomerism. Specific examples include acetylacetone, 2,4-hexanedione, 3,5-heptanedione, 2-methylhexane-3,5-dione, 6-methylheptane-2,4-dione, 2,6-dimethylheptane- Β-diketones such as 3,5-dione; acetoacetates such as methyl acetoacetate, ethyl acetoacetate, isopropyl acetoacetate, tert-butyl acetoacetate; ethyl propionyl acetate, ethyl propionyl acetate, isopropyl propionyl acetate, propionyl acetate propionyl acetates such as tert-butyl; isobutyryl acetates such as ethyl isobutyryl acetate, ethyl isobutyryl acetate, isopropyl isobutyryl acetate, tert-butyl isobutylyl acetate; malonates such as methyl malonate and ethyl malonate; etc. And the like. Among these, acetylacetone and acetoacetic acid esters are preferable compounds. Such compounds that produce keto-enol tautomerism may be used alone or in combinations of two or more.

  Content of the compound which produces the keto-enol tautomerism can be 0.1-20 mass parts with respect to 100 mass parts of said acrylic polymers (B), and usually 0.5-15. It is appropriate to set it as a mass part (for example, 1-10 mass parts). If the amount of the compound is too small, it may be difficult to achieve a sufficient use effect. On the other hand, if the compound is used more than necessary, it may remain in the pressure-sensitive adhesive layer and reduce the cohesive force.

<Method for producing pressure-sensitive adhesive layer>
The method for producing the pressure-sensitive adhesive layer of the present invention is a method for producing the pressure-sensitive adhesive layer, wherein the rubber-based polymer (A) and the polymerizable monomer (b) constituting the monomer unit of the acrylic-based polymer (B), And the step of preparing the pressure-sensitive adhesive composition by mixing the hydrogenated tackifying resin (C), and polymerizing the pressure-sensitive adhesive composition with radiation energy to thereby convert the rubber-based polymer (A). And a step of preparing a pressure-sensitive adhesive layer forming a dispersed phase containing the continuous phase and the acrylic polymer (B).
By mixing the rubber-based polymer (A) using the polymerizable monomer (b), the rubber-based polymer (A) is dissolved or dispersed in the polymerizable monomer (b). Therefore, when the polymerization reaction is advanced based on the radiation energy, the acrylic polymer (B) is contained (as the main component) together with the continuous phase containing the rubber polymer (A) (as the main component). A dense phase separation structure having a dispersed phase can be formed. By having the phase-separated structure, not only the function of the acrylic polymer (B) but also the function of the rubber polymer (A) can be exhibited, and the adhesion property to the adherend with low surface energy is excellent. A pressure-sensitive adhesive layer can be obtained and is useful.

The method for forming the pressure-sensitive adhesive layer having a phase separation (sea island) structure composed of a continuous phase and a dispersed phase according to the present invention is specifically described below.
(1) First, the rubber-based polymer (A) is polymerized by mixing and stirring the rubber-based polymer (A) with the polymerizable monomer (b) which is a monomer component for forming the acrylic polymer (B). A solution (or dispersion) in which the monomer (b) is uniformly mixed (dissolved or dispersed) is prepared.
(2) Subsequently, the hydrogenated tackifier resin (C) and, if necessary, other polymerizable monomer (b), a polymerization initiator, a polyfunctional monomer, and the like are added thereto and stirred again. Then, a uniform pressure-sensitive adhesive composition (solution) is prepared.
(3) The pressure-sensitive adhesive composition (solution) is coated on the release-treated surface of a release-treated substrate (for example, polyethylene terephthalate film) to form a pressure-sensitive adhesive layer having a predetermined thickness, thereby blocking oxygen. For the purpose, the other release-treated substrate (for example, polyethylene terephthalate film) is bonded to the coated surface and irradiated with radiation energy (for example, ultraviolet (UV)).
(4) Upon irradiation with radiation energy (for example, ultraviolet rays (UV)), the polymerizable monomer (b) is polymerized, and the raw materials constituting the pressure-sensitive adhesive composition are cross-linked to convert the rubber polymer (A) to (main) A pressure-sensitive adhesive layer having a phase separation structure formed from a continuous phase containing (as a component) and a dispersed phase containing (as a main component) an acrylic polymer (B) can be prepared.
In this case, the hydrogenated tackifier resin (C) having high compatibility with the rubber polymer (A) is mainly present in the continuous phase.

  In the pressure-sensitive adhesive layer having a phase separation (sea island) structure composed of a continuous phase and a dispersed phase according to the present invention, the maximum length of the domain related to the dispersed phase when observed with a transmission electron microscope (TEM) photograph is about 8 μm or less. Preferably, the thickness is about 10 nm to 6 μm, more preferably about 100 nm to 4 μm or less. If the maximum length of the domain is within the above range, the rubber component (rubber polymer (A)) having a specific function has a structure that looks like a dense network (continuous phase, sea phase), The structure (dispersed phase, island phase) that mainly contains acrylic component (acrylic polymer (B)) in the mesh is used, so the specific (desired) function of the rubber component is fully demonstrated. Therefore, only by adding a small amount of the rubber component, the characteristics of both the acrylic component and the rubber component can be exhibited, which is useful. On the other hand, if the maximum length of the domain exceeds 8 μm, for example, the dispersed phase becomes too large, and there is a possibility that the specific (desired) function of the rubber component forming the continuous phase cannot be sufficiently exhibited (does not appear). .

  Examples of the method for observing the morphology of the pressure-sensitive adhesive layer of the present invention include an analysis method using an electron microscope such as SEM and TEM. For example, the one shown in FIG.

  Note that the composition distribution of each phase of the phase-separated pressure-sensitive adhesive layer can be determined by determining the ease with which the dyeing agent is dyed, or by combining conventionally known composition analysis techniques.

<Adhesive sheet>
The pressure-sensitive adhesive sheet of the present invention preferably has the pressure-sensitive adhesive layer. The pressure-sensitive adhesive sheet is a so-called pressure-sensitive adhesive sheet with a substrate in which the pressure-sensitive adhesive layer is fixedly provided on one or both sides of a sheet-like substrate (support), that is, without intention to separate the pressure-sensitive adhesive layer from the substrate. Alternatively, the pressure-sensitive adhesive layer may be provided on a substrate having releasability such as a release liner (release paper, a resin sheet having a surface subjected to a release treatment), and the pressure-sensitive adhesive layer is supported at the time of application. A so-called substrate-less pressure-sensitive adhesive sheet in which the substrate is removed may be used. The concept of the pressure-sensitive adhesive sheet herein may include what are called pressure-sensitive adhesive tapes, pressure-sensitive adhesive labels, pressure-sensitive adhesive films and the like. The pressure-sensitive adhesive layer is not limited to those formed continuously, and may be a pressure-sensitive adhesive layer formed in a regular or random pattern such as a spot or stripe.

As the substrate (support), for example,
Plastic films such as polypropylene film, ethylene-propylene copolymer film, polyester film, polyvinyl chloride film;
Foam substrates such as polyurethane foam and polyethylene foam;
Kraft paper, crepe paper, Japanese paper, etc .;
Cotton, soft cloth, etc .;
Nonwoven fabrics such as polyester nonwoven fabrics and vinylon nonwoven fabrics;
Metal foil such as aluminum foil and copper foil;
Etc. can be appropriately selected and used depending on the application of the pressure-sensitive adhesive sheet. As the plastic film, any of an unstretched film and a stretched (uniaxially stretched or biaxially stretched) film can be used. Further, the surface of the substrate on which the pressure-sensitive adhesive layer is provided may be subjected to surface treatment such as application of a primer and corona discharge treatment. The thickness of the substrate can be appropriately selected according to the purpose, but is generally about 10 μm to 500 μm (typically 10 μm to 200 μm).

  The pressure-sensitive adhesive layer is a cured layer of the pressure-sensitive adhesive composition. After the pressure-sensitive adhesive composition (solution) is applied (for example, applied) to an appropriate substrate (support), a curing treatment is appropriately performed. Can be formed. When performing 2 or more types of hardening processes (drying, bridge | crosslinking, superposition | polymerization, etc.), these can be performed simultaneously or in multiple steps. In a pressure-sensitive adhesive composition using a partial polymer (acrylic polymer syrup), typically, as the curing treatment, a final copolymerization reaction is performed (the partial polymer is subjected to a further copolymerization reaction). A complete polymer is formed). For example, if a photocurable pressure-sensitive adhesive composition is used, light irradiation is performed. If necessary, curing treatment such as cross-linking and drying may be performed. For example, when it is necessary to dry with a photocurable pressure-sensitive adhesive composition, photocuring may be performed after drying. In the pressure-sensitive adhesive composition using a completely polymerized product, typically, as the curing treatment, treatments such as drying (heat drying) and crosslinking are performed as necessary.

  The method of applying the pressure-sensitive adhesive composition (solution) is carried out using a conventional coater such as a gravure roll coater, reverse roll coater, kiss roll coater, dip roll coater, bar coater, knife coater, spray coater, etc. Can do. In the case of a pressure-sensitive adhesive sheet with a base material, the pressure-sensitive adhesive composition may be directly applied to the base material to form a pressure-sensitive adhesive layer. The pressure-sensitive adhesive layer formed on the release liner is transferred to the base material. May be.

  The thickness of the pressure-sensitive adhesive layer constituting the pressure-sensitive adhesive sheet is not particularly limited, but usually, for example, about 10 μm or more, preferably about 20 μm or more, and more preferably about 30 μm or more provides good adhesive properties. Can be done. For example, it is appropriate that the thickness of the pressure-sensitive adhesive layer is about 10 to 250 μm.

  Moreover, the adhesive sheet which concerns on this embodiment is used suitably for the use which bonds various optical members, for example to a liquid crystal cell, an optical polyester film, a touch panel member, etc. Therefore, the technique shown here includes a laminate in which the pressure-sensitive adhesive layer of the present invention is provided on an optical member. This laminate typically has a form in which the pressure-sensitive adhesive layer on the optical member is protected by a release liner. The optical member provided with such an adhesive layer can be easily attached to, for example, the surface of a plastic cover lens panel, glass, liquid crystal cell, or the like. The optical member is not particularly limited, and may be a polarizing film, a retardation film, a transparent conductive film (ITO film), or the like. Such an optical member may have a single layer structure made of the same material or a multilayer structure made of a plurality of materials. As a method of forming the pressure-sensitive adhesive layer on the optical member, a method of directly applying or a method of transferring can be appropriately employed as in the case of forming the pressure-sensitive adhesive layer on the substrate (support). Typically, the pressure-sensitive adhesive layer formed on the release liner is transferred to the base surface of the optical member.

  In addition, the pressure-sensitive adhesive layer (pressure-sensitive adhesive sheet) according to this embodiment includes, for example, PP (polypropylene), ABS (acrylonitrile-butadiene-styrene copolymer), SBS (styrene-butadiene-styrene block copolymer), PC ( Polycarbonate), PVC (vinyl chloride), PMMA (polymethyl methacrylate resin) and other resins including acrylic resins, and members made of metals such as SUS and aluminum It can be suitably used for applications where it is bonded (fixed) to the surface of building materials, home appliances and the like.

  EXAMPLES The present invention will be described in detail below based on examples, but the present invention is not limited to these examples.

  Tables 1 and 2 show the component contents of the pressure-sensitive adhesive compositions according to Examples 1 to 12 and Comparative Examples 1 to 13. The evaluation results are shown in Table 3.

Example 1
(Preparation of adhesive composition)
As a polymerizable monomer (b), a mixed monomer liquid of 40 parts by mass of butyl acrylate (BA) and 40.8 parts by mass of 2-ethylhexyl acrylate (2EHA), a rubber-based polymer (A), polystyrene-ethylenebutylene-styrene tri After adding 15 parts by mass of block polymer (SEBS, manufactured by Kuraray Co., Ltd., Septon 8007, styrene (St) content: 30% by mass) and mixing and stirring until uniform, as hydrogenated tackifying resin (C), 18 parts by mass of a hydrogenated petroleum resin (Arakawa Chemical Industries, Ltd., Alcon P-115) and 4.2 parts by mass of acrylic acid (AA) were added and mixed and stirred until uniform. Subsequently, 0.05 parts by mass of 1-hydroxy-cyclohexyl-phenyl-ketone (trade name: Irgacure 184, manufactured by BASF) and 2,2-dimethoxy-1,2-diphenylethane- 1-one (trade name: Irgacure 651, manufactured by BASF) 0.05 parts by mass and, as a polyfunctional monomer, 0.08 parts by mass of trimethylolpropane triacrylate were added, and these were mixed uniformly. A pressure-sensitive adhesive composition (solution) was prepared.

(Preparation of adhesive layer)
The pressure-sensitive adhesive composition (solution) has a final dry thickness of 50 μm on the release-treated surface of a 38 μm-thick polyester film (trade name: Diafoil MRF, manufactured by Mitsubishi Plastics Co., Ltd.) having one surface peeled with silicone. In this way, a coating layer was formed.
Next, on the surface of the coating layer, a 38 μm thick polyester film (trade name: Diafoil MRE, manufactured by Mitsubishi Plastics Co., Ltd.), one side of which is peeled off with silicone, is placed on the coating layer side of the film. And coated. Thereby, the coating layer of the pressure-sensitive adhesive composition was shielded from oxygen.
Subsequently, a UV light having an illuminance of 5 mW / cm ² (measured with Topcon UVR-T1 having a maximum sensitivity of about 350 nm) is applied to the coating layer using a black light lamp (device name: black light lamp, manufactured by Toshiba Corporation). The pressure-sensitive adhesive layer (50 μm) was obtained by irradiation for 360 seconds to cause photopolymerization / crosslinking reaction. In addition, the polyester film coat | covered on both surfaces of the said adhesive layer was used as a peeling liner.
As a result of observing the cross section of the obtained pressure-sensitive adhesive layer with a transparent electron microscope (TEM) (device name: HF-2000, manufactured by Hitachi, Ltd.) (see FIG. 2), a phase mainly composed of a rubber-based polymer (A) Is a continuous phase, and it can be confirmed that the phase mainly composed of the acrylic polymer (B) is a dispersed phase, and the hydrogenated tackifier resin (C) is a dispersed phase mainly composed of the rubber polymer (A). I was able to guess that it was unevenly distributed.

(Examples 2, 8, and 9)
As rubber-based polymer (A), in addition to SEBS (Clayton Polymer Japan Co., Ltd., Kraton G1657M, St content: 13% by mass), polystyrene-ethylenepropylene diblock copolymer (SEP, Kuraray Co., Ltd., Septon 1020) , St content: 36% by mass) According to the same procedure as in Example 1, an adhesive layer (thickness: 50 μm) composed of the adhesive composition having the composition shown in Table 1 was obtained.

(Examples 3 and 12)
Except that SEP (Kuraray Co., Ltd., Septon 1020, St content: 36% by mass) was used as the rubber-based polymer (A), an adhesive having the composition shown in Table 1 according to the same procedure as in Example 1. A pressure-sensitive adhesive layer (thickness: 50 μm) comprising the adhesive composition was obtained.

(Examples 4, 6, and 7)
As the rubber-based polymer (A), polystyrene-ethylenepropylene-styrene triblock copolymer (SEPS, manufactured by Kuraray Co., Ltd., Septon 2063, St content: 13% by mass) and SEP (manufactured by Kuraray Co., Ltd., Septon 1020, St content) : 36 mass%) was used in the same manner as in Example 1 to obtain a pressure-sensitive adhesive layer (thickness: 50 μm) composed of the pressure-sensitive adhesive composition having the composition shown in Table 1.

(Example 5)
The same procedure as in Example 4 except that N-vinyl-2-pyrrolidone (NVP) was used instead of acrylic acid (AA) as the polymerizable monomer (b) constituting the acrylic polymer (B). Thus, an adhesive layer (thickness: 50 μm) composed of the adhesive composition having the composition shown in Table 1 was obtained.

(Example 10)
As hydrogenated tackifying resin (C), in addition to Archon P-115, Imabu P100 (Idemitsu Kosan Co., Ltd., hydrogenated dicyclopentadiene resin) was used, except that it was the same as Example 4. According to the procedure, an adhesive layer (thickness: 50 μm) composed of an adhesive composition having the composition shown in Table 1 was obtained.

(Example 11)
Example 4 except that Alcon M-115 (Arakawa Chemical Industries, Ltd., partially hydrogenated petroleum resin) was used as the hydrogenated tackifying resin (C) in addition to Alcon P-115. According to the same procedure, an adhesive layer (thickness: 50 μm) comprising an adhesive composition having the composition shown in Table 1 was obtained.

(Comparative Example 1)
Except that SEBS (Clayton Polymer Japan Co., Ltd., Kraton G1657M, St content: 13% by mass) was used as the rubber-based polymer (A), and the hydrogenated tackifying resin (C) was not blended. According to the same procedure as in Example 1, a pressure-sensitive adhesive layer (thickness: 50 μm) composed of the pressure-sensitive adhesive composition having the composition shown in Table 2 was obtained.

(Comparative Example 2)
As the polymerizable monomer (b) constituting the acrylic polymer (B), butyl acrylate (polymerizable monomer (b): (b1)) and acrylic acid (AA) are used, and the rubber polymer (A) is used. A pressure-sensitive adhesive composition having the composition shown in Table 2 was prepared according to the same procedure as in Example 1 except that SEBS (manufactured by Kraton Polymer Japan Co., Ltd., Kraton G1657M, St content: 13% by mass) was used. . The prepared pressure-sensitive adhesive composition was gelled, and it was difficult to obtain a pressure-sensitive adhesive layer by coating.

(Comparative Example 3)
As the polymerizable monomer (b) constituting the acrylic polymer (B), 2-ethylhexyl acrylate (2EHA) (polymerizable monomer (b): (b2)) and acrylic acid (AA) are used, and a rubber polymer. (A) Adhesive composition having the composition shown in Table 2 in the same manner as in Example 1 except that SEBS (Clayton Polymer Japan Co., Ltd., Kraton G1657M, St content: 13% by mass) was used. A pressure-sensitive adhesive layer (thickness: 50 μm) was obtained.

(Comparative Example 4)
As the polymerizable monomer (b) constituting the acrylic polymer (B), butyl acrylate (polymerizable monomer (b): (b1)) and acrylic acid (AA) are used, and the rubber polymer (A) is used. Example 1 except that SEBS (Clayton Polymer Japan Co., Ltd., Kraton G1657M, St content: 13% by mass) and SEP (Kuraray Co., Ltd., Septon 1020, St content 36% by mass) were used. A pressure-sensitive adhesive composition having the composition shown in Table 2 was prepared according to the same procedure as described above. The prepared pressure-sensitive adhesive composition was gelled, and it was difficult to obtain a pressure-sensitive adhesive layer by coating.

(Comparative Example 5)
As the rubber-based polymer (A), SEBS (Clayton Polymer Japan Co., Ltd., Kraton G1657M, St content: 13% by mass) and SEP (Kuraray Co., Ltd., Septon 1020, St content 36% by mass) are used. A pressure-sensitive adhesive layer (thickness: 50 μm) composed of the pressure-sensitive adhesive composition having the composition shown in Table 2 was obtained according to the same procedure as in Example 1 except that the above-described steps were performed.

(Comparative Example 6)
As the polymerizable monomer (b) constituting the acrylic polymer (B), 2-ethylhexyl acrylate (2EHA) (polymerizable monomer (b): (b2))) and acrylic acid (AA) are used, and rubber-based SEBS (Clayton Polymer Japan Co., Ltd., Kraton G1657M, St content: 13% by mass) and SEP (Kuraray Co., Ltd., Septon 1020, St content 36% by mass) were used as the polymer (A). Except for the above, a pressure-sensitive adhesive layer (thickness: 50 μm) composed of the pressure-sensitive adhesive composition having the composition shown in Table 2 was obtained according to the same procedure as in Example 1.

(Comparative Example 7)
SEPS (Kuraray Co., Ltd., Septon 2063, St content: 13 mass%) and SEP (Kuraray Co., Ltd., Septon 1020, St content 36 mass%) were used as the rubber-based polymer (A). Except for the above, a pressure-sensitive adhesive layer (thickness: 50 μm) composed of the pressure-sensitive adhesive composition having the composition shown in Table 2 was obtained according to the same procedure as in Example 1.

(Comparative Example 8)
As the polymerizable monomer (b) constituting the acrylic polymer (B), 2-ethylhexyl acrylate (polymerizable monomer (b): (b2)) and acrylic acid (AA) are used, and the rubber-based polymer (A) The same procedure as in Example 1 except that SEPS (Kuraray Co., Ltd., Septon 2063, St content 13 mass%) and SEP (Kuraray Co., Ltd., Septon 1020, St content 36 mass%) were used. Thus, an adhesive layer (thickness: 50 μm) comprising an adhesive composition having the composition shown in Table 2 was obtained.

(Comparative Example 9)
As rubber-based polymer (A), SEPS (manufactured by Kuraray Co., Ltd., Septon 2063, St content 13 mass%) and as hydrogenated tackifying resin (C), solid obtained by dissolving Alcon P-115 in toluene The final thickness of only 40% by weight of the polymer solution on the release surface of a 38 μm thick polyester film (trade name: Diafoil MRF, manufactured by Mitsubishi Plastics, Inc.) with one side peeled with silicone. The film was applied to a thickness of 50 μm, dried at 100 ° C. for 2 minutes, and the pressure-sensitive adhesive surface was bonded to the surface peeled with MRF silicone to obtain a pressure-sensitive adhesive layer (thickness: 50 μm).

(Comparative Example 10)
As rubber-based polymer (A), SEBS (Clayton Polymer Japan Co., Ltd., Kraton G1657M, St content 13% by mass) and hydrogenated tackifier resin (C) were dissolved in Alcon P-115 in toluene. In addition, a polymer solution having a solid content of 40% by mass is finally peeled off only by solid content on the surface of a 38 μm-thick polyester film (trade name: Diafoil MRF, manufactured by Mitsubishi Plastics Co., Ltd.) having one surface peeled with silicone. Was applied at a thickness of 50 μm, dried at 100 ° C. for 2 minutes, and the adhesive surface was bonded to the surface that had been peeled off with MRF silicone to obtain an adhesive layer (thickness: 50 μm). .

(Comparative Example 11)
(Preparation of partial polymer)
2-ethylhexyl acrylate (2EHA) 90 parts by mass, acrylic acid (AA) 10 parts by mass, photopolymerization initiator (trade name: Irgacure 184, manufactured by BASF) 0.05 part by mass, and photopolymerization initiator (trade name: 0.05 mass of Irgacure 651 (manufactured by BASF) was put into a four-necked flask to prepare a uniform mixed solution.
Next, the mixed solution was subjected to illuminance of 5 mW / cm ² (measured with Topcon UVR-T1 having a maximum sensitivity of about 350 nm) using a black light lamp (device name: black light lamp, manufactured by Toshiba Corporation) under a nitrogen atmosphere. Was irradiated for 300 seconds and partially photopolymerized to obtain a partially polymerized product (solution) (acrylic polymer syrup) having a polymerization rate of about 8% by mass.

(Preparation of adhesive layer)
To 100 parts by mass of the acrylic polymer syrup, 0.03 parts by mass of a polyfunctional monomer hexanediol diacrylate as a crosslinking agent was added and mixed uniformly to prepare an adhesive composition (solution). Using this pressure-sensitive adhesive composition, in the same manner as in Example 1, a coating layer was formed, and further a photopolymerization / crosslinking reaction was carried out to thereby form a pressure-sensitive adhesive layer comprising a pressure-sensitive adhesive composition having the composition shown in Table 2 ( Thickness: 50 μm) was obtained.

(Comparative Example 12)
(Acrylic polymer (1): (2EHA / AA = 98/2) Production of solution)
160 parts by mass of ethyl acetate, 98 parts by mass of 2-ethylhexyl acrylate, and 2 parts by mass of acrylic acid were charged into a four-necked flask. Then, after stirring at 60 ° C. for 1 hour in a nitrogen atmosphere, 0.2 part by mass of azobisisobutyronitrile as a thermal polymerization initiator was added and reacted at 60 ° C. for 4 hours. By reacting for a period of time, an ethyl acetate solution of acrylic polymer (1) (2EHA / AA = 98/2) was obtained.

(Production of acrylic polymer (2): (BA / AA = 95/5) solution)
230 parts by mass of ethyl acetate, 95 parts by mass of butyl acrylate, and 5 parts by mass of acrylic acid were charged into a four-necked flask. Then, after stirring at 63 ° C. for 1 hour in a nitrogen atmosphere, 0.2 part by mass of azobisisobutyronitrile as a thermal polymerization initiator was added and reacted at 63 ° C. for 8 hours, whereby an acrylic polymer (2 ) (BA / AA = 95/5) in ethyl acetate was obtained.

(Preparation of mixture solution)
The acrylic polymer (1) solution and the acrylic polymer (2) solution are mixed, and further, as a rubber-based polymer (A), SEBS (manufactured by Kraton Polymer Japan Co., Ltd., Kraton G1645M, St content: 13% by mass), SEP (Kuraray Co., Ltd., Septon 1020, St content: 36% by mass) is added and mixed and stirred until uniform, and then hydrogenated petroleum resin (Arakawa Chemical) is used as the hydrogenated tackifying resin (C). Kogyo Co., Ltd., Alcon P-115) was added, and the mixture was further stirred until it became uniform, to obtain a mixture (solution) having a composition ratio shown in Table 2 as a solid content.

(Preparation of adhesive layer)
0.1 parts by mass of an epoxy compound (manufactured by Mitsubishi Gas Chemical Co., Ltd., Tetrad C) as a crosslinking agent is added to 100 parts by mass of the solid content of the mixture (solution). A product (solution) was obtained.
Subsequently, the pressure-sensitive adhesive composition (solution) was applied to the final solid content on the release-treated surface of a 38 μm-thick polyester film (trade name: Diafoil MRF, manufactured by Mitsubishi Plastics Co., Ltd.) whose one surface was peeled with silicone. The coating layer was formed so as to have a thickness of 50 μm, and this was dried at 110 ° C. for 2 minutes to obtain an adhesive layer (thickness: 50 μm). In addition, the composition ratio (mass part) of the last acrylic monomer unit of the acrylic polymer component in the said adhesive layer is BA / 2EHA / AA = 38/39/3.

(Comparative Example 13)
Other than using SEPS (Kuraray Co., Ltd., Septon 2063, St content: 13% by mass) and SEP (Kuraray Co., Ltd., Septon 1020, St content: 36% by mass) as the rubber-based polymer (A). Obtained a pressure-sensitive adhesive layer (thickness: 50 μm) comprising a pressure-sensitive adhesive composition having the composition shown in Table 2 according to the same procedure as in Comparative Example 12.

  Abbreviations in Table 1 and Table 2 indicate the following compounds. In addition, in a table | surface, it is the mass part number of solid content.

SEBS: polystyrene-ethylenebutylene-styrene triblock copolymer SEPS: polystyrene-ethylenepropylene-styrene triblock copolymer SEP: polystyrene-ethylenepropylene diblock copolymer SBS: polystyrene-butadiene-styrene triblock copolymer

Alcon P-115: Partially hydrogenated petroleum resin (softening point is about 115 ° C)
Imabe P100: Hydrogenated dicyclopentadiene resin (softening point is about 100 ° C)
Alcon M-115: Partially hydrogenated petroleum resin (softening point is about 115 ° C)

BA: butyl acrylate 2EHA: 2-ethylhexyl acrylate AA: acrylic acid NVP: N-vinyl-2-pyrrolidone

(Test method)
[180 ° peeling adhesion test]
One release liner (polyester film) of the pressure-sensitive adhesive layer sheet according to each example and each comparative example is peeled off, and a 50 μm-thick polyethylene terephthalate film (trade name: Lumirror S10 manufactured by Toray Industries, Inc.) is bonded. The test piece (length 80 mm × width 20 mm) was cut into 20 mm width. In addition, a 2 mm thick polypropylene (PP) plate (Part No. 1600, manufactured by Takiron Co., Ltd.) and an acrylic (PMMA) plate (acrylite, manufactured by Mitsubishi Rayon Co., Ltd.) cleaned with isopropyl alcohol were prepared. Then, the other release liner (polyester film) of the pressure-sensitive adhesive layer sheet was peeled off, and a 2 kg roller was reciprocated to attach the pressure-sensitive adhesive surface of the pressure-sensitive adhesive layer sheet to the polypropylene plate and the acrylic plate.
After attaching the adhesive layer sheet to the polypropylene plate and acrylic plate, after 48 hours have passed in an environment of 23 ° C., the other end of the adhesive layer sheet is peeled off in a peeling direction of 180 degrees at a speed of 300 mm / min. And the adhesive force (resistance force) (unit: N / 20mm) with respect to the adherend at that time was measured. In each of the polypropylene plate and the acrylic plate, the case where the adhesive strength was 12 N / 20 mm or more was judged as good, and the case where it was less than 12 N / 20 mm was judged as bad. Table 3 shows the measurement results.

[Retention test]
One release liner (polyester film) of the pressure-sensitive adhesive layer sheet according to each example and each comparative example is peeled off, and a 50 μm-thick polyethylene terephthalate film (trade name: Lumirror S10 manufactured by Toray Industries, Inc.) is bonded. The test piece was cut to a width of 10 mm. The adhesive surface of the test piece was bonded to a bakelite plate cleaned with toluene in an area of width 10 mm × length 20 mm, and left in an environment of 60 ° C. for 30 minutes. Thereafter, a weight was suspended at one end of the test piece so that a load of 500 g was applied in the shear direction, and the weight was left suspended in an environment of 60 ° C. for 1 hour in a suspended state to evaluate the retention. The case where the test piece did not fall for 1 hour was evaluated as good (◯), and the case where it dropped was regarded as defective (×). Table 3 shows the measurement results.

[Repulsion resistance test]
The pressure-sensitive adhesive layer sheets according to each Example and each Comparative Example were cut to a width of 10 mm and a length of 90 mm, and bonded to a clean aluminum plate having a thickness of 0.3 mm, a width of 10 mm, and a length of 90 mm. A test piece was obtained. Next, the test piece was curved so that the curvature would be R50 mm by placing the aluminum plate side of the test piece along the cylinder. Then, the other release liner (polyester film) of the pressure-sensitive adhesive layer sheet was peeled off and laminated to the above-described polypropylene (PP) plate and acrylic (PMMA) plate. With the test piece laminated to the polypropylene plate and acrylic plate, the distance at which the pressure-sensitive adhesive layer sheet floated after 1 hour at room temperature (25 ° C.), that is, the distance from the surface of the polypropylene plate and acrylic plate to the pressure-sensitive adhesive layer ( The average height of both ends) (unit: mm) was measured. The case where the floated distance was 10 mm or less was considered good, and the case where the floated distance exceeded 10 mm was judged as defective. Table 3 shows the measurement results. The numerical values shown in Table 3 are average values for two points at both ends in the longitudinal direction.

注）表中の「逆相分離」とは、本発明における「相分離」構造とは、逆に、ゴム系ポリマー（Ａ）を主成分として含有するのが分散相であり、アクリル系ポリマー（Ｂ）を主成分として含有するのが連続相である粘着剤層の構造（図１参照）を意味する。

Note) “Reverse phase separation” in the table is, contrary to the “phase separation” structure in the present invention, the dispersed phase containing the rubber-based polymer (A) as a main component, and the acrylic polymer ( Containing B) as a main component means the structure of the pressure-sensitive adhesive layer that is a continuous phase (see FIG. 1).

  As shown in Table 3 above, it was confirmed that in all Examples, the adhesive properties (adhesiveness, holding property, and repulsion resistance) of the adhesive layer (adhesive sheet) were excellent. In particular, it was confirmed that the adhesive properties to low surface energy polypropylene (PP) were excellent. It was also confirmed that a desired phase separation structure was formed.

  On the other hand, in the comparative example, the adhesive layer (adhesive sheet) that does not satisfy all of the tackiness, holding property, and repulsion resistance cannot be obtained, and in particular, the adhesive property to low surface energy polypropylene (PP). It was confirmed that it was inferior. In particular, in Comparative Examples 2 and 4, although the detailed reason is not clear, the monomer (b1) which does not contain the monomer (b2) and has a relatively high polarity (SP value) (butyl acrylate calculated from the Fedors equation) SP value is 9.77, which has a high polarity.), And therefore has poor compatibility with the rubber polymer (A) having a low polarity (SP value), and an appropriate flow of the mixture (compound). It is presumed that the adhesive property layer could not be maintained and became a gel and the pressure-sensitive adhesive layer could not be formed. In Comparative Examples 5 and 7, since the mass ratio (b1 / b2) is outside the desired range, it is confirmed that the rebound resistance is poor. In Comparative Examples 12 and 13, the rubber-based polymer (A) is mainly used. Since it is a pressure-sensitive adhesive layer that forms a dispersed phase containing it and forms a continuous phase mainly containing acrylic polymers (1) and (2), it has poor adhesiveness and retention, and exhibits the properties of rubber components sufficiently. It was confirmed that it was not possible.

1 Dispersed phase (mainly rubber-based polymer)
2 Continuous phase (mainly acrylic polymer)
10 Adhesive layer 20 Continuous phase (mainly rubber-based polymer (A))
30 Dispersed phase (mainly acrylic polymer (B))

Claims (6)

A continuous phase containing a rubber polymer (A), an acrylic polymer (B), and a hydrogenated tackifying resin (C) and containing a rubber polymer (A), and an acrylic polymer (B ) Is a pressure-sensitive adhesive layer in which a dispersed phase is formed,
The pressure-sensitive adhesive layer forms a phase separation structure;
The rubber polymer (A) contains a saturated styrene diblock copolymer,
The saturated styrenic diblock copolymer comprises a polystyrene-ethylenepropylene diblock copolymer;
The acrylic polymer (B) is
As the polymerizable monomer (b) constituting the monomer unit of the acrylic polymer (B), at least a (meth) acrylic acid alkyl ester monomer (b1) having an alkyl group having 1 to 4 carbon atoms, and 5 carbon atoms. (Meth) acrylic acid alkyl ester monomer (b2)) having ˜20 alkyl groups,
The blending ratio (b1 / b2) (mass ratio) of the monomer (b1) and the monomer (b2) is 25/75 to 85/15,
The pressure-sensitive adhesive layer, wherein a blending ratio (A / B) (mass ratio) of the rubber polymer (A) to the acrylic polymer (B) is 10/100 to 50/100.   The pressure-sensitive adhesive layer according to claim 1, wherein the tackifying resin (C) is contained in the continuous phase in a larger amount than in the dispersed phase.   The acrylic polymer (B) further contains a nitrogen atom-containing vinyl monomer and / or a carboxyl group-containing vinyl monomer as the polymerizable monomer (b) constituting the monomer unit. 3. The pressure-sensitive adhesive layer according to 1 or 2.   The pressure-sensitive adhesive layer according to any one of claims 1 to 3, wherein the acrylic polymer (B) is obtained by polymerizing the polymerizable monomer (b) with radiation energy. Pressure-sensitive adhesive sheet characterized by having a pressure-sensitive adhesive layer according to any one of claims 1-4. It is a manufacturing method of the adhesive layer in any one of Claims 1-4 , Comprising:
The rubber-based polymer (A), the polymerizable monomer (b) constituting the monomer unit of the acrylic polymer (B), and the hydrogenated tackifying resin (C) are mixed to prepare a pressure-sensitive adhesive composition. A step of preparing;
A pressure-sensitive adhesive layer that forms a continuous phase containing the rubber-based polymer (A) and a dispersed phase containing the acrylic-based polymer (B) by polymerizing the pressure-sensitive adhesive composition with radiation energy. And a step of preparing the pressure-sensitive adhesive layer.

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