JP2015160905A - Adhesive layer, adhesive sheet and method of producing adhesive layer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an adhesive layer which allows sufficient exertion of characteristics of polymer ingredients used in formation of the adhesive layer by forming a phase separation structure composed of a continuous phase and a dispersion phase and having a dense network structure, an adhesive sheet having the adhesive layer, and a method of producing the adhesive layer.SOLUTION: An adhesive layer contains a polymer (A) and a polymer (B) and is composed of a continuous phase containing the polymer (A) and a dispersion phase containing the polymer (B). In the adhesive layer, the continuous phase and the dispersion phase are formed by polymerizing an adhesive composition containing polymerizable monomers (b) constituting the monomer units of the polymers (A) and (B) with radiation energy.

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. However, there is actually 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.

  Therefore, an acrylic polymer that is generally used for adhesive sheets is a polymer that exhibits excellent adhesive properties (for example, a rubber-based polymer) to a low surface energy (low polarity) adherend such as a polyolefin resin. It is also conceivable to produce a pressure-sensitive adhesive sheet by blending in a small amount together with these, etc. However, since the compatibility between these polymers is usually low, the adhesive properties of the surface energy (low polarity) to the adherend are sufficient. Not obtained.

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

  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 polymer (A) and a polymer (B), and a continuous phase containing the polymer (A) and a dispersed phase containing the polymer (B) are formed. The pressure-sensitive adhesive layer is a pressure-sensitive adhesive composition containing a polymerizable monomer (b) constituting a monomer unit of the polymer (A) and the polymer (B). The continuous phase and the dispersed phase are formed by polymerization.

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

  The method for producing a pressure-sensitive adhesive layer according to the present invention is a method for producing the pressure-sensitive adhesive layer, comprising mixing the polymer (A) and a polymerizable monomer (b) constituting a monomer unit of the polymer (B). The step of preparing the pressure-sensitive adhesive composition, and the continuous phase containing the polymer (A) by polymerizing the pressure-sensitive adhesive composition with radiation energy, and the dispersed phase containing the polymer (B) And a step of preparing a pressure-sensitive adhesive layer forming the layer.

  According to the present invention, since the obtained pressure-sensitive adhesive layer can form a phase separation structure formed from a continuous phase and a dispersed phase that look like a dense network, it is used when forming a pressure-sensitive adhesive layer. The characteristics of the polymer component can be fully exhibited, which is useful. In particular, by using a plurality of polymer components having different characteristics, the characteristics of each polymer can be exhibited, which 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 schematic diagram which shows the state which melt | dissolved and disperse | distributed the polymer (A) in the polymerizable monomer (b) at the time of preparing the adhesive layer which concerns on this embodiment. A state in which the polymerizable monomer (b) at the time of preparing the pressure-sensitive adhesive layer according to this embodiment is polymerized to form a polymer (B), and the polymer (A) and the polymer (B) start to form a phase-separated structure. It is a schematic diagram which shows. It is a schematic diagram which shows the phase-separation structure of the adhesive layer which concerns on this embodiment. It is a transmission electron microscope (TEM) photograph (magnification: 12000 times) of the adhesive layer concerning this embodiment.

  Normally, adding a small amount of a rubber polymer (rubber component) having a specific function to the acrylic polymer (acryl component) used in the adhesive (layer) results in insufficient compatibility of both components. In the obtained adhesive (layer), a continuous phase (sea phase) mainly composed of an acrylic component and a dispersed phase (island phase) mainly composed of a rubber component form a so-called sea-island structure. As such a structure, for example, like the pressure-sensitive adhesive layer 10 shown in FIG. 1, the rubber component forms the dispersed phase 1 (island phase), and the acrylic component forms the continuous phase 2 (sea phase). Visual observation is possible by using a transmission electron microscope (TEM photograph). The pressure-sensitive adhesive layer having such a structure is not compatible with a rubber component having a specific function, but the function cannot be fully exhibited. Is inferior and also inferior in economic efficiency.

  On the other hand, the pressure-sensitive adhesive layer 10 according to this embodiment contains the polymer (A) (for example, a rubber component), the polymer (B) (for example, an acrylic component) composed of a specific monomer unit, and the like. It becomes possible to have a dense phase separation structure in which a continuous phase (sea phase) 20 mainly containing the polymer (A) and a dispersed phase (island phase) 30 mainly containing the polymer (B) are formed. As such a structure, for example, as shown in FIGS. 4 and 5 (FIG. 4 corresponds to a schematic diagram showing an enlarged structure in FIG. 5), the polymer (A ) (For example, rubber component) is formed as a continuous phase (sea phase) 20, and polymer (B)) (for example, an acrylic component) as a dispersed phase (island phase) 30 is formed. The pressure-sensitive adhesive layer having such a structure forms a structure (continuous phase, sea phase) in which the polymer (A) having a specific function (for example, a rubber component) looks like a dense network. In particular, since the polymer (B) (for example, acrylic component) is included (dispersed phase, island phase), the specific (desired) function of the polymer (A) is sufficiently exerted, and a small amount of The characteristics of both the components of the polymers (A) and (B) can be exhibited only by blending the polymer (A), which is useful. Although the details of the reason for adopting such a structure are not clear, for example, a polymerizable monomer (b) (see FIG. 2), which is a precursor of a polymer (B) poorly compatible with the polymer (A), is polymerized. -In the process of curing, the polymer (B) chains with high fluidity (and those containing the polymerizable monomer (b)) are combined to reduce the contact area with the polymer (A). (Agglomeration / polymerization) is repeated (see FIG. 3), and finally an island-like phase (island phase, dispersed phase) (and polymer (A) formed from polymer (B) with poor fluidity It is presumed that this is because it forms a sea-like phase (sea phase, continuous phase) (see FIG. 4) and is 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.

  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. Hereinafter, the polymer (A) and the polymer (B), which are essential components of the pressure-sensitive adhesive layer of the present invention, may be referred to as “(A) component” and “(B) component”, respectively. is there.

<Polymer (A) (component (A))>
The pressure-sensitive adhesive layer of the present invention is characterized by containing a polymer (A). As the polymer (A), when the polymer (B) blended together with the polymer (A) is contained, a continuous phase is formed. If it is a polymer that can be contained and can form a continuous phase and is usually used in the field of pressure-sensitive adhesives, it can be used without any particular limitation. For example, various polymers such as acrylic polymer, rubber polymer, silicone polymer, polystyrene polymer, olefin polymer, polyvinyl acetal polymer, polyurethane polymer, and polyester polymer are used as the polymer (A). Can do. In particular, acrylic polymers and rubber polymers from the viewpoints of ease of control of aging resistance (heat resistance, etc.) and adhesive properties (adhesion, retention, repulsion resistance, etc.), cost and versatility. Are preferably used.

<(A) component: acrylic polymer>

  The pressure-sensitive adhesive layer of the present invention is preferably an acrylic polymer as the polymer (A). Since the polymer (A) is an acrylic polymer, it is excellent in terms of ease of control of anti-aging properties (heat resistance, etc.) and adhesive properties (adhesion, retention, repulsion resistance, etc.). Is useful.

  The acrylic polymer is, for example, a monomer unit of (meth) acrylic acid alkyl ester having a linear or branched alkyl group having 1 to 20 carbon atoms as a polymerizable monomer constituting the monomer unit of the acrylic polymer. It is preferable to contain as a main component. The monomers can be used alone or in a combination of two or more. The main component means the component having the largest content ratio in the component, preferably more than 30% by mass, more preferably more than 40% by mass, and still more preferably more than 50% by mass, The same applies hereinafter.

  The ratio of the (meth) acrylic acid alkyl ester having a linear or branched alkyl group having 1 to 20 carbon atoms exceeds 50% by mass with respect to the total amount of monomer units for preparing the acrylic polymer. It is preferable to contain, 60-99.9 mass% is more preferable, 70-99.5 mass% or less is still more preferable, 80-99 mass% is especially preferable. Within the above range, the adhesive properties (particularly adhesive strength and wettability to the adherend) are excellent, which is a preferred embodiment.

Examples of the (meth) acrylic acid alkyl ester having a linear or branched alkyl group having 1 to 20 carbon atoms (C _1-20 ) include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, Propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, (meth) acryl Pentyl acid, isopentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, (meth) Nonyl acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, (meth) acrylic Isodecyl acid, undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate, tetradecyl (meth) acrylate, pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, (meth) acrylic acid (Meth) acrylic such as cetyl, isocetyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, isostearyl (meth) acrylate, nonadecyl (meth) acrylate, eicosyl (meth) acrylate Acid C _1-20 alkyl ester is preferable, (meth) acrylic acid C _2-14 alkyl ester is more preferable, and (meth) acrylic acid C _2-10 alkyl ester is more preferable. In addition, (meth) acrylic acid alkyl ester means acrylic acid alkyl ester and / or methacrylic acid alkyl ester, and “(meth)...” Has the same meaning.

  The acrylic polymer may contain other monomer components (others) that can be copolymerized with the (meth) acrylic acid alkyl ester, if necessary, for the purpose of modifying cohesion, heat resistance, crosslinkability, and the like. (Co) polymerizable monomer) may be included. Among them, as the other (co) polymerizable monomer, a monomer having a polar group (polar machine-containing monomer) can be preferably used. Specifically, the carboxyl group-containing monomer and the hydroxyl group-containing monomer shown below can be used. , (N-substituted) amide monomers, nitrogen-containing heterocyclic monomers, and the like.

As a specific example of the (co) polymerizable monomer,
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 can be used individually or in combination of 2 or more types.

  The content of the (co) polymerizable monomer is not particularly limited. Usually, the polymerizable monomer is added in an amount of 0.1 to 0.1% with respect to the total amount of monomer units (100% by mass) for preparing the acrylic polymer. The content is preferably 40% by mass, more preferably 0.5 to 35% by mass, and still more preferably 1 to 30% by mass. By containing 0.1% by mass or more of the polymerizable monomer, it is possible to maintain the pressure-sensitive adhesive (layer) retention and repulsion resistance. In addition, by setting the content of the polymerizable monomer 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.), or increase the adhesive strength. it can.

［式（１）中、Ｒ^１は２価の有機基である］ Moreover, it is preferable to contain a nitrogen atom containing vinyl monomer and / or a carboxyl group containing vinyl monomer among the monomer units (components) described above as the polymerizable monomer constituting the monomer unit of the acrylic polymer. 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 vinyl monomer include carboxyl group-containing monomers such as acrylic acid, methacrylic acid, carboxyethyl acrylate, and carboxypentyl acrylate. Among these, N-vinyl-2-pyrrolidone (R ¹ has a propylene group which is a divalent organic group) or acrylic acid can be suitably used.

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

  Although it does not restrict | limit especially as content of the said (co) polymerizable monomer represented by the said General formula (1), Usually, 0.1-0.1 with respect to the monomer unit whole quantity for preparing the said acrylic polymer. It is preferable to contain 40 mass%, More preferably, it is 0.5-35 mass%, More preferably, it is 1-30 mass%. If it is within the above range, the pressure-sensitive adhesive layer has excellent adhesive properties, which is a preferred embodiment.

  Further, the acrylic polymer may contain a polyfunctional monomer as a monomer unit (polymerizable monomer) as necessary in order 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. Polyfunctional (meth) acrylate can be used individually or in combination of 2 or more types.

  The content of the polyfunctional monomer varies depending on the molecular weight, the number of functional groups, etc., but is 0.01% with respect to the total amount of monomer units (components) for preparing the polymer (A) (for example, acrylic polymer). 10 mass% is preferable, More preferably, it is 0.02-7 mass%, More preferably, it can add so that it may become 0.03-5 mass%. When content of the said polyfunctional monomer exceeds 10 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.

  A method for synthesizing the polymer (A) (for example, an acrylic polymer) is not particularly limited, and as a method for synthesizing an acrylic polymer such as solution polymerization, emulsion polymerization, bulk polymerization, suspension polymerization, and radiation curing polymerization, Various polymerization methods commonly used can be applied.

<Polymerization initiator>
In the preparation of the polymer (A), it is preferable that the polymerizable monomer is obtained by polymerization with radiation energy (for example, irradiation with heat, ultraviolet rays, etc.) when polymerizing the polymerizable monomer. 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 suitably used from 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.

  The content of the thermal polymerization initiator is not particularly limited, but is preferably 0.01 to 5 parts by mass with respect to 100 parts by mass of the total amount of monomer units (polymerizable monomers) for preparing the polymer (A). 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 (2,4,4 -Trimethylbenzoyl) phenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) -2,4-dibutoxyphenylphosphine oxide, 1,10-bis [bis (2,4,6-trimethylbenzoyl) phosphine oxide] Examples include decane and tri (2-methylbenzoyl) phosphine oxide.

  The content of the photopolymerization initiator is not particularly limited. For example, 0.01% with respect to 100 parts by mass of the total amount of monomer units (polymerizable monomer) for preparing the polymer (A) (for example, acrylic polymer). -5 mass parts is preferable, More preferably, it is 0.05-3 mass parts. 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 weight average molecular weight (Mw) of the polymer (A) is preferably, for example, 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 is a case where the wetness with respect to the body is insufficient and the adhesive strength is lowered.

  The weight average molecular weight 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.

  As said polymer (A), it is preferable that the glass transition temperature (Tg) is less than 120 degreeC, More preferably, it is less than 90 degreeC, More preferably, it is less than 70 degreeC, Usually -80 degreeC or more It is. When the glass transition temperature (Tg) of the polymer (A) is 120 ° C. or higher, the polymer is difficult to flow, wetness to the adherend becomes insufficient, and adhesive strength may be reduced.

  In the present invention, when the polymer (A) is a copolymer, its glass transition temperature (Tg) can be calculated based on the following formula (2) (Fox formula).

_{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 (eg, polymer handbook, adhesive handlog).

<(A) component: Rubber polymer>
In a preferred embodiment of the pressure-sensitive adhesive layer of the present invention, the polymer (A) is a rubber-based polymer. For example, when the polymer (B) described later is an acrylic polymer, the rubber-based polymer is a normal rubber-based polymer even when the blending ratio of the rubber-based polymer is lower than that of the acrylic polymer. When a so-called phase-separated (sea island) structure is formed, such as a pressure-sensitive adhesive (layer) obtained by blending a polymer and an acrylic polymer, the rubber-based polymer is a continuous component that occupies most of the pressure-sensitive adhesive (layer). Rather than forming a dispersed phase (island phase) in the phase (sea phase), a continuous phase (sea phase) can be formed, that is, a dense phase separation structure (see FIG. 5) can be formed, It is also useful for adherends with low surface energy (for example, polyolefins) because they can exhibit excellent adhesive properties due to the rubber-based polymer.

  Examples of the rubber-based polymer include copolymers such as polybutadiene, polyisoprene, polyisobutylene, polystyrene-butadiene-styrene, polystyrene-isoprene-styrene, polystyrene-isobutylene-styrene, polystyrene-vinyl polyisoprene-styrene, polystyrene-vinyl polyisoprene. Styrene-based triblock copolymers such as ethylenepropylene-styrene, polystyrene-butadiene, polystyrene-isoprene, polystyrene-isobutylene, polystyrene-vinylpolyisoprene, styrene-based diblock copolymers such as polystyrene-vinylpolyisoprene-ethylenepropylene, polyethylenepropylene, Olefin copolymers such as polyethylene butene and polypropylene butene, Styrene-ethylene butylene-styrene, polystyrene-ethylene-ethylene propylene-styrene, polystyrene-ethylene propylene-styrene, polystyrene-butadiene-butylene-styrene, polystyrene-hydrogenated vinyl polyisoprene-styrene, polystyrene-hydrogenated vinyl polyisoprene-ethylene Partially hydrogenated or fully hydrogenated styrene triblock copolymers such as propylene-styrene, polystyrene-ethylenebutylene, polystyrene-ethylene-ethylenepropylene, polystyrene-ethylenepropylene, polystyrene-butadiene-butylene, polystyrene-hydrogenated vinylpolyisoprene , Polystyrene-hydrogenated vinyl polyisoprene-ethylenepropylene and other partially hydrogenated or fully hydrogenated styrene diblocks It can be used various rubber polymers such as copolymers. 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 is a copolymer having polystyrene blocks, the proportion of polystyrene blocks in the copolymer (styrene (St) content) is preferably 2 to 80% by mass, more preferably 3 to 75% by mass. More preferably, it is 5-65 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.

<Polymer (B) (component (B))>
The pressure-sensitive adhesive layer of the present invention is characterized by containing a polymer (B), and when the polymer (B) contains the polymer (A) blended together with the polymer (B), it becomes a dispersed phase. Any polymer that can be contained and can form a dispersed phase and that is usually used in the field of pressure-sensitive adhesives can be used without particular limitation. For example, various polymers such as acrylic polymer, rubber polymer, silicone polymer, polystyrene polymer, olefin polymer, polyvinyl acetal polymer, polyurethane polymer, and polyester polymer are used as the polymer (B). Can do. In particular, acrylic polymers are preferably used from the viewpoints of ease of control of aging resistance (heat resistance, etc.) and adhesive properties (adhesion, retention, repulsion resistance, etc.), cost and versatility. It is done.

  In the pressure-sensitive adhesive layer of the present invention, the polymer (B) contains a polymerizable monomer (b) constituting a monomer unit, and the polymer (B) polymerizes the polymerizable monomer (b) by radiation energy. It is preferable that it is obtained. As the polymerizable monomer (b), a polymerizable monomer constituting a monomer unit similar to the component (A) described above can be used. By irradiating the pressure-sensitive adhesive composition containing the polymer (A) and the polymerizable monomer (b) with radiation energy, in the vicinity (periphery) of the polymer (A), the polymerizable monomer (b) The polymer (B) can form a dispersed phase (island phase) having a phase separation (sea island) structure, and the polymer (A) can form a continuous phase (sea phase). It is useful because a morphological pressure-sensitive adhesive layer having a phase separation (sea-island) structure excellent in the above can be formed.

<(B) component: acrylic polymer>
In the pressure-sensitive adhesive layer of the present invention, it is preferable that the polymerizable monomer (b) is an acrylic monomer and the polymer (B) is an acrylic polymer. When the polymer (B) is an acrylic polymer, it is excellent in terms of controllability of anti-aging properties (heat resistance, etc.) and adhesive properties (adhesion, retention, repulsion resistance, etc.). Because it is useful.

As the polymerizable monomer (b), a polymerizable monomer that can be used as the monomer unit of the component (A) described above can be used in the same manner. For example, the above-described linear or branched group having 1 to 20 carbon atoms (C _1-20 ) It is preferable to contain (meth) acrylic acid alkyl ester having a chain alkyl group as the main component of the monomer unit, more preferably (meth) acrylic acid C _3-14 alkyl ester, and still more preferably (meth). Acrylic acid C _4-12 alkyl ester. In addition, the proportion of the (meth) acrylic acid alkyl ester having a linear or branched alkyl group having 1 to 20 carbon atoms is based on the total amount of monomer units for preparing the acrylic polymer (B). It is preferable to contain 80-100 mass% or more, 85-100 mass% is more preferable, 90-100 mass% is still more preferable, 95-100 mass% is especially preferable. Within the above range, the adhesive properties (particularly adhesive strength and wettability to the adherend) are excellent, which is a preferred embodiment. In addition, when the polymer (A) and the polymer (B) have exactly the same composition, it becomes difficult to form a dense phase separation structure. Therefore, the polymer (polymer In the case of (B), it is a preferred embodiment to use a monomer that changes the type of the polymerizable monomer (b).

  In addition, as the polymerizable monomer (b) other than the (meth) acrylic acid alkyl ester having a linear or branched alkyl group having 1 to 20 carbon atoms, it can be used as a monomer unit of the component (A) described above. Other (co) polymerizable monomers can be used in the same manner as the polymerizable monomer (b). Usually, the polymerization is performed 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 a property monomer (b), More preferably, 0.5-30 mass%, More preferably, it can contain 1-20 mass%. By containing 1% by mass or more of the polymerizable monomer (b), it is possible to maintain the pressure-sensitive adhesive (layer) retention 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.

  The method for synthesizing the polymer (B) (for example, an acrylic polymer) is the same as the polymer (A) described above.

  The weight average molecular weight (Mw) of the polymer (B) is preferably, for example, 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 is a case where the wetness with respect to the body is insufficient and the adhesive strength is lowered. In addition, the measuring method of a weight average molecular weight is the same as that of the polymer (A) mentioned above.

  In addition, the glass transition temperature (Tg) of the said polymer (B) is less than 0 degreeC, Preferably, it is less than -10 degreeC, More preferably, it is less than -40 degreeC, and is -80 degreeC or more normally. When the glass transition temperature (Tg) of the polymer (B) is 0 ° C. or higher, the polymer is difficult to flow, wetness to the adherend becomes insufficient, and adhesive strength may be reduced. In addition, the measuring method of glass transition temperature (Tg) is the same as that of the polymer (A) mentioned above.

  The pressure-sensitive adhesive layer of the present invention preferably has a blending ratio (A / B) (mass ratio) of the polymer (A) to the polymer (B) of 3/100 to 150/100. 100/100 is more preferable, 7/100 to 70/100 is still more preferable, and 10/100 to 50/100 is particularly preferable. Within the above range, the pressure-sensitive adhesive (layer) as shown in FIG. 5 can form a dense phase separation structure (sea-island structure), adhesive strength to the adherend, retention (cohesive strength), It has excellent adhesive properties such as resilience and is useful.

The pressure-sensitive adhesive layer of the present invention has a difference in solubility parameter (SP) value ((cal / cm ³ ) ^1/2 ) calculated from the Fedors equation of the polymer (A) and the polymer (B) is 0. It is preferable to use one adjusted to 2 or more, more preferably 0.4 or more, and still more preferably 0.6 or more. For example, when the polymers (A) and (B) are both the same type of polymer, the polymer (A) having such a difference in SP value is used to form (prepar) a desired phase separation structure. And the polymer (B) can form a dense phase separation structure (sea-island structure) with the adhesive (layer). Adhesive strength to the adherend, retention (cohesive strength), resilience resistance, etc. It has excellent adhesive properties and is useful.

  Based on a specific solubility parameter (SP) value, it has a phase separation structure composed of a continuous phase containing the polymer (A) (as the main component) and a dispersed phase containing the polymer (B) (as the main component). As a method of forming the pressure-sensitive adhesive layer, radiation energy (for example, ultraviolet (UV)) is irradiated to a mixture in which an arbitrary monomer component for constituting the polymer (A) and a polymerization initiator are blended. , Preparing a partially polymerized product (polymer syrup) in which the monomer component is partially polymerized, and then mixing the polymerizable monomer (b) with the polymer syrup to obtain a pressure-sensitive adhesive composition. The difference between the SP value of the polymer (A) and the SP value of the polymerizable monomer (b) (the component that will later become the polymer (B)) is adjusted to provide a difference of 0.2 or more. Further, the adhesive composition is irradiated with radiation energy (for example, ultraviolet (UV)) to polymerize and cure the polymerizable monomer (b), and contains a polymer (A) (as a main component). It is possible to form a pressure-sensitive adhesive layer having a phase separation (sea island) structure composed of a dispersed phase containing the polymer (B) (as a main component).

  In addition, as a method of knowing the solubility parameter (SP) value of the polymer, a method using a conventionally known estimation equation such as a Fedors equation, a Small equation, or a Vam Krebelen equation, a method of actually measuring by experiments, and the like can be mentioned. Among these, in order to obtain a simple and reasonable estimated value, it is a preferable aspect in the present invention to use the Fedors equation.

In the present invention, the SP value of the polymer component can be calculated based on the following formula (3) (Fedors formula).
SP value ((cal / cm ³ ) ^1/2 ) = (Σei / Σvi) ^0.5 (3)
[In formula (3), 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. ]

  In order to obtain a polymer having a desired SP value, attention should be paid to the functional group of the monomer constituting the polymer, and a monomer having a suitable functional group may be appropriately used. For example, a polymer having a high SP value can be obtained by using many monomers having a functional group having a relatively high polarity such as a carboxyl group, an amide group, or a hydroxyl group. Further, a polymer having a low SP value can be obtained by using a small amount of the monomer having a functional group having a relatively high polarity or a large amount of a monomer having a functional group having a relatively low polarity.

  The acrylic polymer (B) is an alkyl (meth) acrylate 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). It contains an ester monomer (b1) and a (meth) acrylic acid alkyl ester monomer (b2) having an alkyl group having 5 to 20 carbon atoms, and the blending ratio of the monomer (b1) and the monomer (b2) (b1 / b2) (Mass ratio) is preferably 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) as a main component, when the polymer (A) is, for example, a rubber-based polymer, moderate compatibility with the rubber-based polymer and adhesive properties when a pressure-sensitive adhesive layer is formed It becomes easier to balance and is a preferred embodiment. The alkyl group may be linear or branched.

[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 preferably 25/75 to 85/15. More preferably, it is 35 / 65-85 / 15, More preferably, it is 45 / 55-85 / 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 an appropriate compatibility with a rubber polymer when the polymer (A) is a rubber polymer, for example, by using a (meth) acrylic acid alkyl ester monomer (group) having different polarities as a main component. And it becomes easier to balance the adhesive properties when the pressure-sensitive adhesive layer is formed, and this is a preferred embodiment. 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 polymer When (A) is, for example, a rubber-based polymer, the compatibility between the rubber-based polymer and the polymerizable monomer (b) becomes poor, and the mixed (blended) product becomes a gel or the target phase separation structure (see FIG. 4 and FIG. 5), it is difficult to form a pressure-sensitive adhesive layer.

<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 field of pressure-sensitive adhesives can be used. 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 polymerizable monomer (b) which comprises the said 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. These compounds may be used alone or in combination of two or more.

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

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

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

  Although the content of the crosslinking agent used in the present invention is not particularly limited, for example, it is contained in an amount of 0.001 to 3 parts by mass with respect to 100 parts by mass of the polymerizable monomer (b) constituting the polymer (B). The content is preferably 0.01 to 2 parts by mass. 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) becomes small, and when the content of the cross-linking agent exceeds 3 parts by mass, the cohesive force of the pressure-sensitive adhesive (layer) Is large, the fluidity is lowered, the wetness to the adherend is insufficient, and the adhesive force may be lowered.

  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 polymer (B) described above, and a photopolymerization initiation assistant. 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 0.1-10 normally normally with respect to 100 mass parts of polymerizable monomers (b) which comprise the said polymer (B), for example. It is preferable to mix | blend a mass part and to mix | blend in the range of 0.2-7 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 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 with respect to 100 parts by mass of the polymerizable monomer (b) constituting the polymer (B)). Can be about 0.001 to 0.5 parts by mass).

[Tackifying resin]
Moreover, when preparing the said adhesive composition, tackifying resin can be used in order to improve the adhesive force and durability of the adhesive layer formed with the said adhesive composition more. Moreover, it is a preferable aspect to use in order to obtain sufficient adhesive properties for adherends of low surface energy (low polarity) such as polyolefin.

  The tackifying resin can be used without particular limitation as long as it is usually used in the adhesive field, for example, rosin resin, terpene resin, aliphatic petroleum resin, aromatic petroleum resin, copolymerization. It is preferable to fall into a petroleum petroleum resin, an alicyclic petroleum resin, a xylene resin, a coumarone / indene resin, a styrene resin, an alkylphenol resin, and an elastomer, and more preferably, a derivative obtained by hydrogenating the tackifying resin Specifically, it can be selected from aromatic, dicyclopentadiene, aliphatic, aromatic-dicyclopentadiene copolymer, and the like. 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 is preferably 80 to 200 ° C, more preferably 90 to 180 ° C. When the softening point of the tackifying resin is within the above range, it is possible to achieve both a high adhesive force and a good balance of properties such as excellent retention and repulsion resistance.

  The content of the tackifier resin is preferably 1 to 150 parts by mass, more preferably 2 to 100 parts per 100 parts by mass of the total polymer component (including polymer (A) and polymer (B)). It is a mass part, More preferably, it is 3-80 mass parts. When the content of the tackifying resin is within the above range, the adhesive properties of the pressure-sensitive adhesive sheet can be maintained in a well-balanced manner.

[Acrylic polymer having a weight average molecular weight (Mw) of 1000 or more and less than 30000]
In preparing the pressure-sensitive adhesive composition, the pressure-sensitive adhesive layer formed of the pressure-sensitive adhesive composition exhibits a function as a tackifier resin, and the pressure-sensitive adhesive layer retainability (cohesive force) and repulsion resistance Therefore, it is preferable to contain an acrylic polymer having a weight average molecular weight (Mw) of 1000 or more and less than 30000. By containing the acrylic polymer, the function as a tackifier resin can be exhibited, and the retention (cohesive force) and repulsion resistance of the pressure-sensitive adhesive layer can be enhanced, which is a preferred embodiment. The acrylic polymer is mainly related to a continuous phase containing the polymer (A) (for example, a rubber-based polymer) and a dispersed phase mainly containing the polymer (B) (for example, an acrylic polymer). It is presumed to have a function that brings about a moderate interaction. In addition, by using the acrylic polymer, it is possible to effectively draw out the properties resulting from the rubber-based polymer exhibiting excellent adhesive properties for adherends with low surface energy, and adhesion reliability. It is presumed to improve.

  The acrylic polymer is a polymer having a weight average molecular weight smaller than that of the above-described acrylic polymer (polymer (A), polymer (B)), and is a polymer (for example, UV polymerization) by irradiation with radiation energy. In this case, it has the advantage that it is difficult to cause polymerization inhibition, and not only functions as a tackifier resin, but also increases the cohesive strength of the dispersed phase (island phase), or the continuous phase (sea phase) and dispersed phase ( It is possible to increase the adhesion to the island phase, and it becomes easy to obtain better holding properties and repulsion resistance, which is a preferable embodiment.

The acrylic polymer can be used without particular limitation as long as the weight average molecular weight is 1000 or more and less than 30000. For example, the acrylic polymer has an alicyclic skeleton as a polymerizable monomer constituting the monomer unit of the acrylic polymer. It is preferable to contain a (meth) acrylic monomer, more preferably a (meth) acrylic acid ester represented by the following general formula (4).
CH ₂ = C (R ¹ ) COOR ² (4)
[In Formula (4), R < ¹ > is a hydrogen atom or a methyl group, and R < ² > is a C1-C12 alkyl group or an alicyclic hydrocarbon group. ]

Examples of the alicyclic hydrocarbon group R ² in the general formula (4) include alicyclic hydrocarbon groups such as a cyclohexyl group, an isobornyl group, and a dicyclopentanyl group. Examples of the (meth) acrylic acid ester having such an alicyclic hydrocarbon group include cyclohexyl (meth) acrylate having a cyclohexyl group, isobornyl (meth) acrylate having an isobornyl group, and a dicyclopentanyl group. Mention may be made of esters of (meth) acrylic acid with alicyclic alcohols such as (meth) acrylic acid dicyclopentanyl. By including the acrylic monomer having a relatively bulky structure as a monomer unit (component) in the acrylic polymer, the adhesive strength (adhesive strength) can be improved.

  Further, the alicyclic hydrocarbon group constituting the acrylic polymer preferably has a bridged ring structure. The bridged ring structure refers to an alicyclic structure having three or more rings. By giving the acrylic polymerization a bulky structure such as a bridged ring structure, the adhesive force of the pressure-sensitive adhesive layer (pressure-sensitive adhesive sheet, surface protective sheet) can be further improved.

Examples of R ² that is an alicyclic hydrocarbon group having a bridged ring structure include a dicyclopentanyl group represented by the following formula (3a) and a dicyclopentenyl group represented by the following formula (3b). And adamantyl group represented by the following formula (3c), tricyclopentanyl group represented by the following formula (3d), tricyclopentenyl group represented by the following formula (3e), and the like. In addition, when ultraviolet (UV) polymerization is employed in the synthesis of the acrylic polymer or in the preparation of the pressure-sensitive adhesive composition, it is difficult to cause polymerization inhibition. Among (meth) acrylic monomers having a ring or higher alicyclic structure, in particular, a dicyclopentanyl group represented by the following formula (3a), an adamantyl group represented by the following formula (3c), and the following formula A (meth) acrylic monomer having a saturated structure such as a tricyclopentanyl group represented by (3d) can be suitably used as a monomer constituting the acrylic polymer.

  Examples of (meth) acrylic monomers having a tricyclic or higher alicyclic structure having such a bridged ring structure include dicyclopentanyl methacrylate, dicyclopentanyl acrylate, and dicyclopentanyloxyethyl. Methacrylate, dicyclopentanyloxyethyl acrylate, tricyclopentanyl methacrylate, tricyclopentanyl acrylate, 1-adamantyl methacrylate, 1-adamantyl acrylate, 2-methyl-2-adamantyl methacrylate, 2-methyl-2-adamantyl acrylate, (Meth) acrylic acid esters such as 2-ethyl-2-adamantyl methacrylate and 2-ethyl-2-adamantyl acrylate can be mentioned. These (meth) acrylic monomers can be used alone or in combination of two or more.

  The acrylic polymer may be a homopolymer of a (meth) acrylic monomer having an alicyclic structure, or a (meth) acrylic monomer having an alicyclic structure and another (meth) acrylic acid. It may be a copolymer with an ester monomer or a copolymerizable monomer.

Examples of such (meth) acrylic acid ester monomers include
Methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate, s-butyl (meth) acrylate , T-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, heptyl (meth) acrylate, (meth ) Octyl acrylate, isooctyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, (meth) (Meth) acrylic acid alkyl esters such as dodecyl acrylate;
(Meth) acrylic acid aryl esters such as phenyl (meth) acrylate and benzyl (meth) acrylate;
(Meth) acrylic acid ester obtained from terpene compound derivative alcohol;
Etc. Such (meth) acrylic acid esters can be used alone or in combination of two or more.

  In addition to the (meth) acrylic acid ester component unit, the acrylic polymer is obtained by copolymerizing another monomer component ((co) polymerizable monomer) copolymerizable with (meth) acrylic acid ester. It is also possible to obtain.

As other monomer ((co) polymerizable monomer) copolymerizable with the (meth) acrylic acid ester,
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;
Alkoxyalkyl (meth) acrylates such as methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, propoxyethyl (meth) acrylate, butoxyethyl (meth) acrylate, ethoxypropyl (meth) acrylate monomer;
(Meth) acrylic acid alkali metal salts and the like;
Di (meth) acrylic acid ester of ethylene glycol, di (meth) acrylic acid ester of diethylene glycol, di (meth) acrylic acid ester of triethylene glycol, di (meth) acrylic acid ester of polyethylene glycol, di (meta) of propylene glycol ) Di (meth) acrylate monomers of (poly) alkylene glycols such as acrylate esters, di (meth) acrylate esters of dipropylene glycol, di (meth) acrylate esters of tripropylene glycol;
Polyvalent (meth) acrylate monomers such as trimethylolpropane tri (meth) acrylate;
Vinyl esters such as vinyl acetate and vinyl propionate;
Vinyl halide compounds such as vinylidene chloride and 2-chloroethyl (meth) acrylate;
An oxazoline group-containing polymerizable compound such as 2-vinyl-2-oxazoline, 2-vinyl-5-methyl-2-oxazoline, 2-isopropenyl-2-oxazoline;
Aziridine group-containing polymerizable compounds such as (meth) acryloylaziridine, (meth) acrylic acid-2-aziridinylethyl;
Epoxy group-containing vinyl monomers such as allyl glycidyl ether, (meth) acrylic acid glycidyl ether, (meth) acrylic acid-2-ethylglycidyl ether;
(Meth) acrylic acid-2-hydroxyethyl, (meth) acrylic acid-2-hydroxypropyl, monoester of (meth) acrylic acid and polypropylene glycol or polyethylene glycol, lactones and (meth) acrylic acid-2-hydroxy Hydroxyl group-containing vinyl monomers such as adducts with ethyl;
Fluorine-containing vinyl monomers such as fluorine-substituted (meth) acrylic acid alkyl esters;
Acid anhydride group-containing monomers such as maleic anhydride and itaconic anhydride;
Aromatic vinyl compound monomers such as styrene, α-methylstyrene, vinyltoluene;
Reactive halogen-containing vinyl monomers such as 2-chloroethyl vinyl ether and monochloro vinyl acetate;
(Meth) acrylamide, N-isopropyl (meth) acrylamide, N-butyl (meth) acrylamide, N, N-diethyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-methylol (meth) acrylamide, N An amide group-containing vinyl monomer such as ethylol (meth) acrylamide, N-methylolpropane (meth) acrylamide, N-methoxyethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, N-acryloylmorpholine;
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-vinylpyrazole, N-vinylisoxazole, N-vinylthiazole Nitrogen-containing heterocyclic monomers such as N-vinylisothiazole and N-vinylpyridazine;
N-vinylcarboxylic acid amides;
Lactam monomers such as N-vinylcaprolactam;
Cyanoacrylate monomers such as (meth) acrylonitrile;
(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;
Imide group-containing monomers such as cyclohexylmaleimide and isopropylmaleimide;
Isocyanate group-containing monomers such as 2-isocyanatoethyl (meth) acrylate;
Organosilicon-containing vinyl monomers such as vinyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, allyltrimethoxysilane, trimethoxysilylpropylallylamine, 2-methoxyethoxytrimethoxysilane;
Hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, hydroxyhexyl (meth) acrylate, hydroxyoctyl (meth) acrylate, hydroxydecyl (meth) acrylate, (meta ) Hydroxyl group-containing monomers such as hydroxyalkyl (meth) acrylate such as hydroxylauryl acrylate, (4-hydroxymethylcyclohexyl) methyl methacrylate;
(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;
Olefins or dienes such as ethylene, butadiene, isoprene, isobutylene;
Vinyl ethers such as vinyl alkyl ethers;
Vinyl chloride;
Other examples include macromonomers having a radical polymerizable vinyl group at the terminal of a monomer obtained by polymerizing a vinyl group. These monomers can be copolymerized with the (meth) acrylic acid ester alone or in combination.

  Examples of the acrylic polymer include a copolymer of cyclohexyl methacrylate (CHMA) and isobutyl methacrylate (IBMA), a copolymer of cyclohexyl methacrylate (CHMA) and isobornyl methacrylate (IBXMA), and methyl methacrylate (MMA). Copolymer of isobornyl methacrylate (IBXMA), copolymer of cyclohexyl methacrylate (CHMA) and acryloylmorpholine (ACMO), copolymer of cyclohexyl methacrylate (CHMA) and diethylacrylamide (DEAA), 1-adamantyl acrylate (ADA) ) And methyl methacrylate (MMA) copolymer, dicyclopentanyl methacrylate (DCPMA) and isobornyl methacrylate (IBXMA) copolymer, Copolymer of cyclopentanyl methacrylate (DCPMA) and methyl methacrylate (MMA), copolymer of cyclohexyl methacrylate (CHMA) and methyl methacrylate (MMA), copolymer of dicyclopentanyl methacrylate (DCPMA) and acrylic acid (AA) Polymer, dicyclopentanyl methacrylate (DCPMA), cyclohexyl methacrylate (CHMA), isobornyl methacrylate (IBXMA), isobornyl acrylate (IBXA), dicyclopentanyl acrylate (DCPA), 1-adamantyl methacrylate (ADMA) 1-adamantyl acrylate (ADA) homopolymers, and the like.

  Further, the acrylic polymer may be introduced with a functional group having reactivity with an epoxy group or an isocyanate group. Examples of such functional groups include hydroxyl groups, carboxyl groups, amino groups, amide groups, mercapto groups, and monomers having such functional groups are used in the production of acrylic polymers (copolymerization). )

  When the acrylic polymer is a copolymer of a (meth) acrylic monomer having an alicyclic structure and another (meth) acrylic acid ester monomer or a copolymerizable monomer, it has an alicyclic structure. The content ratio of the (meth) acrylic monomer is preferably 5% by mass or more, more preferably 10% by mass or more, and still more preferably 20% in the total amount (100% by mass) of monomer units (components) constituting the acrylic polymer. % By mass or more, particularly preferably 30% by mass or more (usually less than 100% by mass, preferably 90% by mass or less). Adhesive strength (adhesive strength) can be improved by containing 5% by mass or more of a (meth) acrylic monomer having an alicyclic structure. On the other hand, if it is less than 5% by mass, the adhesive strength may be inferior.

  The acrylic polymer has a weight average molecular weight (Mw) of 1000 or more and less than 30000, preferably 1500 or more and less than 20000, and more preferably 2000 or more and less than 10,000. When the molecular weight is 30000 or more, the effect of improving the adhesive strength in the pressure-sensitive adhesive layer may not be sufficiently obtained. Moreover, since it becomes low molecular weight as it is less than 1000, it may cause the adhesive force of an adhesive layer and a fall of retention property, and is unpreferable.

  The acrylic polymer preferably has a glass transition temperature (Tg) of 0 to 300 ° C, more preferably about 20 to 300 ° C, still more preferably about 40 to 300 ° C. When the glass transition temperature (Tg) is less than 0 ° C., the cohesive force of the pressure-sensitive adhesive layer at room temperature or higher is lowered, and the holding property and the adhesive property at high temperature may be lowered. Table 1 shows the glass transition temperatures of typical materials that can be used as the acrylic polymer in the present embodiment. The glass transition temperature (Tg) shown in Table 1 is a nominal value described in literature (catalog) or the like, or a value calculated based on the above-described Fox equation.

Abbreviations in Table 1 indicate the following compounds.
DCPMA: dicyclopentanyl methacrylate DCPA: dicyclopentanyl acrylate IBXMA: isobornyl methacrylate IBXA: isobornyl acrylate CHMA: cyclohexyl methacrylate CHA: cyclohexyl acrylate IBMA: isobutyl methacrylate MMA: methyl methacrylate ADMA: 1-adamantyl methacrylate ADA: 1-adamantyl acrylate NVP: N-vinyl-2-pyrrolidone HEMA: hydroxyethyl methacrylate

  The acrylic polymer is generally used, for example, in the same manner as the above-described polymers (A) and (B), using solution polymerization, emulsion polymerization, bulk polymerization, suspension polymerization, radiation curing polymerization, etc. as a synthesis method. Various polymerization methods can be applied.

  In order to adjust the weight average molecular weight (Mw) of the acrylic polymer, a chain transfer agent can be used during the polymerization. Examples of the chain transfer agent used include compounds having a mercapto group such as octyl mercaptan, t-nonyl mercaptan, dodecyl mercaptan, t-dodecyl mercaptan, mercaptoethanol, α-thioglycerol; thioglycolic acid, methyl thioglycolate, Ethyl thioglycolate, propyl thioglycolate, butyl thioglycolate, t-butyl thioglycolate, 2-ethylhexyl thioglycolate, octyl thioglycolate, isooctyl thioglycolate, decyl thioglycolate, dodecyl thioglycolate, ethylene Examples include glycol thioglycolate, neopentyl glycol thioglycolate, and pentaerythritol thioglycolate. Particularly preferred chain transfer agents include α-thioglycerol, mercaptoethanol, methyl thioglycolate, ethyl thioglycolate, propyl thioglycolate, butyl thioglycolate, t-butyl thioglycolate, 2-ethylhexyl thioglycolate, Examples include octyl thioglycolate and isooctyl thioglycolate.

  The content of the chain transfer agent is not particularly limited, but usually, the chain transfer agent is preferably about 0.1 to 20 parts by mass with respect to 100 parts by mass of the total monomer units constituting the acrylic polymer. 0.2-15 mass parts is more preferable, More preferably, it is 0.3-10 mass parts. By adjusting the content (addition amount) of the chain transfer agent within the above range, an acrylic polymer having a suitable molecular weight can be obtained. In addition, a chain transfer agent can be used individually or in combination of 2 or more types.

  Further, the content of the acrylic polymer is preferably 0.1 to 50 parts by mass, more preferably 0.5 to 30 parts by mass with respect to 100 parts by mass of the total amount of the polymer components. Preferably it is 1-15 mass parts. When the acrylic polymer is added in an amount exceeding 50 parts by mass, the elastic modulus of the resulting pressure-sensitive adhesive layer is increased, the adhesive properties at low temperatures are deteriorated, and sufficient adhesive force is not exhibited even at room temperature. In some cases, it is not preferable. Moreover, when content of the said acrylic polymer is less than 0.1 mass part, the effect of improving the retention property (cohesive force) and repulsion resistance of an adhesive layer may not be acquired.

  The content ratio (mass ratio) of the acrylic polymer and the tackifier resin is acrylic polymer / tackifier resin = 1/1 to 1/20, preferably 1 / 1.3-1 to 12, more preferably Is 1 / 1.5 to 1/7. If it is within the range of the blending ratio, the acrylic polymer is presumed to work as a compatibilizing agent for the tackifier resin, and the both are uniformly dispersed, thereby improving the adhesion reliability.

<Silane coupling agent>
Further, in preparing the pressure-sensitive adhesive composition, for the purpose of improving the adhesive strength and durability of the pressure-sensitive adhesive layer by increasing the affinity between the adherend and the pressure-sensitive adhesive layer bonded via the pressure-sensitive adhesive layer, A silane coupling agent can be used. The silane coupling agent is not particularly limited, and a known silane coupling agent can be appropriately selected and used. For example, epoxy such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane Group-containing silane coupling agent; 3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, 3-triethoxysilyl-N- (1,3-dimethylbutylidene) propyl Amino group-containing silane coupling agents such as amines; (Meth) acrylic group-containing silane coupling agents such as 3-acryloxypropyltrimethoxysilane and 3-methacryloxypropyltriethoxysilane; 3-isocyanatopropyltriethoxysilane and the like Insane Such as group-containing silane coupling agent. Use of such a silane coupling agent is preferable for improving durability. The said silane coupling agent may be used independently, and may mix and use 2 or more types.

  As content of the said silane coupling agent, it is preferable to contain 0.01-10 mass parts of said silane coupling agents with respect to 100 mass parts of polymer components whole quantity which comprises the said adhesive layer, More preferably, It is 0.02-5 mass parts, More preferably, it is 0.05-2 mass parts. By using the silane coupling agent in the above range, the cohesive force and durability can be improved more reliably.

  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 polymers (B), and usually is 0.5-15 mass parts. (For example, 1 to 10 parts by mass) is appropriate. 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.

  In addition to the above polymer components (polymer (A), polymer (B), etc.), the pressure-sensitive adhesive composition contains various additives that are common in the field of pressure-sensitive adhesives as optional components. Can do. Such optional components include dispersants (dispersion stabilizers), anti-aging agents, antioxidants, processing aids, stabilizers, antifoaming agents, flame retardants, thickeners, plasticizers, softeners, fillers, coloring. Agents (pigments, dyes, etc.), leveling agents, preservatives, antistatic agents, thermal conductive substances, etc. can be added as appropriate within the range not impairing the effects of the present invention.

  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.

  In addition, about the composition distribution of each phase (continuous phase and dispersed phase) of the pressure-sensitive adhesive layer that is phase-separated, or by determining the ease of dyeing of the dyeing agent, or by combining conventionally known composition analysis methods, Judgment is possible.

<Method for producing pressure-sensitive adhesive layer>
The method for producing a pressure-sensitive adhesive layer of the present invention comprises a step of preparing a pressure-sensitive adhesive composition by mixing the polymer (A) and a polymerizable monomer (b) constituting the monomer unit of the polymer (B). Preparing a pressure-sensitive adhesive layer that forms a continuous phase containing the polymer (A) and a dispersed phase containing the polymer (B) by polymerizing the pressure-sensitive adhesive composition with radiation energy; It is preferable to contain. By mixing the polymer (A) synthesized in advance using the polymerizable monomer (b), the polymer (A) is dissolved or dispersed in the polymerizable monomer (b). Therefore, when the polymerization reaction proceeds based on the radiation energy, a continuous phase containing the polymer (A) (as a main component) can be formed and the dispersion containing the polymer (B) (as a main component). A dense phase separation structure having phases can be formed. Although the detailed reason why the polymer (A) is contained in the continuous phase (forms a continuous phase) is not clear, the polymer (A) is aggregated (interaction) in the polymerizable monomer (b). ) To form a continuous phase (sea phase), and the dispersed phase (island phase) is filled with the polymer (B) obtained by the polymerization reaction of the polymerizable monomer (b) around the continuous phase (sea phase). ) (See FIG. 3), it is estimated that a phase separation (sea island) structure is formed (see FIGS. 4 and 5). By having the phase separation (sea island) structure, not only the function of the polymer (B) but also the function of the polymer (A) can be exhibited, which 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 polymer (A) is mixed with the polymerizable monomer (b), which is a monomer component for forming the polymer (B), and stirred, so that the polymer (A) is contained in the polymerizable monomer (b). In step (1), a solution (or dispersion) that is uniformly mixed (dissolved or dispersed) is prepared.
(2) Subsequently, if necessary, other polymerizable monomer (b), a polymerization initiator, a polyfunctional monomer, a tackifier resin, an acrylic polymer, and the like are added, and stirred again to be uniform. An 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, so that the polymer (A) is used as a main component. A pressure-sensitive adhesive layer having a phase separation structure formed from a dispersed phase containing a continuous phase and a polymer (B) (as a main component).

  As a more specific example (1) of the method for preparing the pressure-sensitive adhesive layer, the polymer (A) is a rubber polymer, the polymer (B) is an acrylic polymer, and further a tackifying resin (hydrogenated type). In the case of using an acrylic polymer (weight average molecular weight (Mw) is 1000 or more and less than 30000, and the weight average molecular weight is smaller than that of the acrylic polymer), the structure of the pressure-sensitive adhesive layer is polymer (A) ( It is possible to form a pressure-sensitive adhesive layer having a phase separation (sea island) structure in which a continuous phase containing (as a main component) and a dispersed phase containing polymer (B) (as a main component) are formed.

As a specific example (2) of the method for preparing the pressure-sensitive adhesive layer, the polymer (A) is an acrylic polymer (for example, the SP value ((cal / cm ³ ) ^1/2 ) calculated from the Fedors equation) 9.29) and an acrylic polymer (for example, the SP value calculated from the Fedors equation is 9.77) as the polymer (B) (in the case of the same kind of polymer), the structure of the pressure-sensitive adhesive layer Forming a pressure-sensitive adhesive layer having a phase separation (sea island) structure in which a continuous phase containing polymer (A) (as a main component) and a dispersed phase containing polymer (B) (as a main component) are formed. Is possible. In addition, when a polymer (A) and a polymer (B) are the same kind of polymers, it is preferable that the difference of SP value of both polymers is 0.2 or more.

  As a specific example (3) of the method for preparing the pressure-sensitive adhesive layer, the polymer (A) is a rubber-based polymer, and the polymer (B) is a polymerizable monomer (b) constituting a monomer unit of an acrylic polymer. (Meth) acrylic acid alkyl ester monomer (b1) having at least an alkyl group having 1 to 4 carbon atoms and (meth) acrylic acid alkyl ester monomer (b2) having an alkyl group having 5 to 20 carbon atoms And a blending ratio (b1 / b2) (mass ratio) of the monomer (b1) and the monomer (b2) adjusted to 25/75 to 85/15, and a tackifying resin (hydrogenated type) ), The structure of the pressure-sensitive adhesive layer is a phase separation in which a continuous phase containing the polymer (A) (as the main component) and a dispersed phase containing the polymer (B) (as the main component) are formed. It is possible to form an adhesive layer having a sea-island) structure. In this case, a tackifying resin having high compatibility with the rubber-based polymer is mainly present in the continuous phase.

<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 base material provided with the pressure-sensitive adhesive layer fixed on one or both sides of a sheet-like base material (support), that is, without intention to separate the pressure-sensitive adhesive layer from the base material ( Single-sided or double-sided pressure-sensitive adhesive sheet), or the pressure-sensitive adhesive layer on a substrate having releasability such as a release film (release liner) (release paper, resin sheet having a surface subjected to release treatment). It may be a so-called base material-less (double-sided) pressure-sensitive adhesive sheet in which the base material supporting the pressure-sensitive adhesive layer at the time of sticking is removed. 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.

  Examples of the substrate (support) include plastic substrates such as polyethylene terephthalate (PET) and polyester film, porous materials such as paper and nonwoven fabric, and metal foil.

  The plastic substrate is not particularly limited as long as it can be formed into a sheet shape or a film shape. For example, polyethylene, polypropylene, poly-1-butene, poly-4-methyl-1-pentene, ethylene -Polyolefin films such as propylene copolymer, ethylene / 1-butene copolymer, ethylene / vinyl acetate copolymer, ethylene / ethyl acrylate copolymer, ethylene / vinyl alcohol copolymer; polyethylene terephthalate, polyethylene naphthalate, Polyester film such as polybutylene terephthalate; Polyacrylate film, Polystyrene film, Polyamide film such as nylon 6, Nylon 6,6, Partially aromatic polyamide; Polyvinyl chloride film, Polyvinylidene chloride film, Poly Such as turbo titanate film, and the like.

  The base material has a thickness of usually 4 to 100 μm, preferably about 4 to 25 μm.

  If necessary, the plastic substrate may be released from a silicone, fluorine, long chain alkyl or fatty acid amide release agent, silica powder, etc., and antifouling treatment, acid treatment, alkali treatment, primer treatment. Further, anti-adhesion treatment such as corona treatment, plasma treatment and ultraviolet treatment, coating type, kneading type, vapor deposition type and the like can be carried out.

  Examples of the release film (release liner) include plastic films such as polyethylene, polypropylene, and polyethylene terephthalate, porous materials such as paper, cloth, and nonwoven fabric, nets, foamed sheets, metal foils, and laminates thereof. From the point of excellent surface smoothness, a plastic film is preferably used.

  The plastic film used for the release film is not particularly limited as long as it can protect the pressure-sensitive adhesive layer. For example, a polyethylene film, a polypropylene film, a polybutene film, a polybutadiene film, a polymethylpentene film. Polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polybutylene terephthalate film, polyurethane film, ethylene-vinyl acetate copolymer film, and the like can be used.

  For the release film, if necessary, mold release and antifouling treatment with silicone, fluorine, long chain alkyl or fatty acid amide release agent, silica powder, etc., coating type, kneading type, vapor deposition An antistatic treatment such as a mold may be performed. In particular, the release property from the pressure-sensitive adhesive layer can be further improved by appropriately performing a release treatment such as silicone treatment, long-chain alkyl treatment, or fluorine treatment on the surface of the release film.

  The thickness of the release film is usually about 5 to 200 μm, preferably about 5 to 100 μm.

  The pressure-sensitive adhesive layer of the present invention 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 performed. Can be formed by appropriately applying. 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.

  Examples of the method for applying the pressure-sensitive adhesive composition (solution) include roll coating, kiss roll coating, gravure coating, reverse coating, roll brush, spray coating, dip roll coating, bar coating, knife coating, air knife coating, and curtain coating. A method such as an extrusion coating method using a lip coat or a die coater can be used.

  The thickness of the pressure-sensitive adhesive layer of the present invention is preferably 10 μm to 5 mm, more preferably 20 μm to 2 mm, and further preferably 30 μm to 1 mm. By having such a thickness, good adhesive properties can be realized.

  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.

(Preparation of acrylic polymer (DCPMA homo))
As a polymerizable monomer, 100 parts by mass of dicyclopentanyl methacrylate (DCPMA) (trade name: FA-513M, manufactured by Hitachi Chemical Co., Ltd.), 5 parts by mass of thioglycolic acid (TGA) as a chain transfer agent, and toluene 100 A mass part was put into a four-necked flask. Then, after stirring for 1 hour at 70 ° C. in a nitrogen atmosphere, 0.2 part by mass of azobisisobutyronitrile as a thermal polymerization initiator was added and reacted at 70 ° C. for 2 hours. Reacted for hours. Thereafter, 0.2 part by mass of azobisisobutyronitrile was added and further reacted at 80 ° C. for 3 hours. At this time, the obtained reaction solution was put into a temperature atmosphere of 130 ° C., and toluene, the chain transfer agent, and the unreacted monomer were removed by drying to obtain a solid acrylic polymer (DCPMA homo).
The obtained acrylic polymer (DCPMA homo) had a glass transition temperature (reference values, see Table 1) of 175 ° C. and a weight average molecular weight (Mw) of 1900.

(Production of acrylic polymer (1) (2EHA / AA = 98/2) solution)
160 parts by mass of ethyl acetate, 98 parts by mass of 2-ethylhexyl acrylate (2EHA), and 2 parts by mass of acrylic acid (AA) were charged into a four-necked flask. And after stirring at 60 degreeC by nitrogen atmosphere for 1 hour, 0.2 mass part of azobisisobutyronitrile was thrown in as a thermal-polymerization initiator, and it was made to react at 60 degreeC for 4 hours. Then, the ethyl acetate solution (solid content: 38 mass%) of acrylic polymer (1) was obtained by making it react at 70 degreeC for 3 hours.

(Production of acrylic polymer (2) (BA / AA = 95/5) solution)
230 parts by mass of ethyl acetate, 95 parts by mass of butyl acrylate (BA), and 5 parts by mass of acrylic acid (AA) 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 ) Solution of ethyl acetate (solid content: 30% by mass).

Example 1
(Preparation of adhesive composition)
As a polymerizable monomer (b), a mixed monomer liquid of 38 parts by mass of butyl acrylate (BA) and 38 parts by mass of 2-ethylhexyl acrylate (2EHA), and as a polymer (A), polystyrene-ethylenebutylene-styrene which is a rubber-based polymer After adding 20 parts by mass of triblock polymer (SEBS, manufactured by Kraton Polymer Japan Co., Ltd., Kraton G1645M, styrene (St) content: 12.5% by mass), stirring and mixing until uniform, hydrogen as tackifier resin 14 parts by mass of additive-type petroleum resin (Arakawa Chemical Industries, Ltd., Alcon P-115), 4 parts by mass of the above-mentioned acrylic polymer (DCPMA homo), and 4 parts by mass of acrylic acid (AA) are added uniformly. Mix and stir until. 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 adhesive layer (adhesive layer alone thickness: 50 μm) (adhesive layer with a double-sided release liner) 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 a cross section of the obtained pressure-sensitive adhesive layer with a transparent electron microscope (TEM) (device name: HF-2000, manufactured by Hitachi, Ltd.), a phase mainly composed of a rubber-based polymer becomes a continuous phase, and an acrylic polymer. It was confirmed that the phase mainly composed of was a dispersed phase.

(Comparative Example 1)
(Preparation of adhesive composition)
40 parts by mass of the solid content of the acrylic polymer (1) solution and 40 parts by mass of the solid content of the acrylic polymer (2) solution are mixed, and SEBS (Clayton Polymer Japan Co., Ltd.), which is a rubber-based polymer, is further used as the polymer (A). Made by Kraton G1645M, St content: 13% by mass), and after mixing and stirring until uniform, as a tackifying resin, a hydrogenated petroleum resin (Arakawa Chemical Industries, Ltd., Alcon P-115) ) 18 parts by mass and 4 parts by mass of the above-mentioned acrylic polymer (DCPMA homo) were added and further mixed and stirred until uniform, to prepare a mixture (solution) that had a composition ratio as shown in Table 2. .
Furthermore, 0.1 parts by mass of an epoxy compound (manufactured by Mitsubishi Gas Chemical Co., Ltd., Tetrad C) as a cross-linking agent was added to 100 parts by mass of the solid content of the mixture (solution), and mixed and stirred until uniform. A pressure-sensitive adhesive composition (solution) was obtained.

(Preparation of adhesive layer)
The pressure-sensitive adhesive composition (solution) was peeled on a surface of a 38 μm-thick polyester film (trade name: Diafoil MRF, manufactured by Mitsubishi Plastics Co., Ltd.) having one surface peeled off with silicone, and a final dry thickness of 50 μm. It applied so that an application layer might be formed.
The coating layer was dried at 110 ° C. for 2 minutes to obtain an adhesive layer (thickness: 50 μm).
In addition, the composition ratio (part by mass) of the acrylic monomer unit that is a constituent unit of the acrylic polymer is BA / 2EHA / AA = 38/39/3.

(Comparative Example 2)
As the polymer (A), SEPS (Kuraray Co., Ltd., Septon 2063, St content: 13% by mass) and SEP (Kuraray Co., Ltd., Septon 1020, St content: 36% by mass) are used as the polymer (A). A pressure-sensitive adhesive layer composed of a pressure-sensitive adhesive composition having the composition shown in Table 2 was obtained in the same manner as in Comparative Example 1 except that the above-described steps were performed.

(Example 2)
(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), and as a polymer (A), polystyrene-ethylenebutylene which is a rubber-based polymer -Styrene triblock polymer (SEBS, manufactured by Kuraray Co., Ltd., Septon 8007, styrene (St) content: 30% by mass) 15 parts by mass, mixed and stirred until uniform, and hydrogenated as a tackifying resin 18 parts by mass of petroleum resin (manufactured by Arakawa Chemical Industry Co., 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 a cross section of the obtained pressure-sensitive adhesive layer with a transparent electron microscope (TEM) (device name: HF-2000, manufactured by Hitachi, Ltd.), a phase mainly composed of a rubber-based polymer becomes a continuous phase, and an acrylic polymer. It was confirmed that the phase mainly composed of was a dispersed phase.

(Comparative Example 3)
(Preparation of mixture solution)
The acrylic polymer (1) solution and the acrylic polymer (2) solution are mixed, and further, as a polymer (A), SEBS (manufactured by Kraton Polymer Japan Co., Ltd., Kraton G1645M, St content: 13) Mass%) and SEP (Kuraray Co., Ltd., Septon 1020, St content: 36 mass%), and after mixing and stirring until uniform, a hydrogenated petroleum resin (Arakawa Chemical Industries, Ltd.) is used as a tackifying resin. 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 4)
As the polymer (A), SEPS (Kuraray Co., Ltd., Septon 2063, St content: 13% by mass) and SEP (Kuraray Co., Ltd., Septon 1020, St content: 36% by mass), which are rubber-based polymers, were used. Except for this, a pressure-sensitive adhesive layer (thickness: 50 μm) comprising a pressure-sensitive adhesive composition having the composition shown in Table 2 was obtained according to the same procedure as in Comparative Example 3.

  Abbreviations in 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 Alcon P-115: partially hydrogenated petroleum resin (softening point is about 115 ° C. )
BA: butyl acrylate 2EHA: 2-ethylhexyl acrylate AA: acrylic acid DCPMA: dicyclopentanyl methacrylate CHMA: cyclohexyl methacrylate

(Test method)
[180 ° peel adhesion test]
One release liner (polyester film) of the pressure-sensitive adhesive layer sheet (pressure-sensitive adhesive layer with double-sided release liner) according to each example and each comparative example was peeled off, and a polyethylene terephthalate film having a thickness of 50 μm (manufactured by Toray Industries, Inc., A product name: Lumirror S10) was bonded and cut into a 20 mm width to obtain a test piece (length 80 mm × width 20 mm). 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 the 2 kg roller was reciprocated to attach the pressure-sensitive adhesive surface of the pressure-sensitive adhesive layer to each of the polypropylene plate and the acrylic plate.
After pasting the pressure-sensitive adhesive layer on the polypropylene plate and acrylic plate, after allowing 48 hours to pass in an environment of 23 ° C., the other end of the pressure-sensitive adhesive layer was peeled off at a rate of 300 mm / min in a peeling direction of 180 degrees, The adhesive force (resistance force) (unit: N / 20 mm) 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. The measurement results are shown in Table 3.

[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 (×). The measurement results are shown in Table 3.

[Repulsion resistance test]
One release liner (polyester film) of the pressure-sensitive adhesive layer sheet according to each example and each comparative example was peeled off and cut into a width of 10 mm and a length of 90 mm to obtain a thickness of 0.3 mm, a width of 10 mm, and a length of 90 mm. This was bonded to a clean aluminum plate and used as a test piece. 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 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 (both ends (Average of height) (unit: mm). 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. The measurement results are shown in Table 3. The numerical values shown in Table 3 are average values for two points at both ends in the longitudinal direction.

注）表３中の比較例は、実施例とは逆の相分離構造を形成している。つまりは、実施例においては、連続相に主として、ポリマー（Ａ）（ゴム系ポリマー）を含有しているのに対して、比較例においては、分散相に主として、ポリマー（Ａ）（ゴム系ポリマー）を主成分として含有する、いわゆる逆相分離構造を形成していた（図１のような構造）。

Note) The comparative examples in Table 3 form a phase separation structure opposite to the examples. That is, in the examples, the polymer (A) (rubber polymer) is mainly contained in the continuous phase, whereas in the comparative example, the polymer (A) (rubber polymer is mainly contained in the dispersed phase. ) As a main component, so-called reverse phase separation structure was formed (structure as shown in FIG. 1).

  From the results in Table 3, it was confirmed that in the examples, a pressure-sensitive adhesive layer having a dense network structure and having excellent adhesive properties was obtained (see, for example, FIG. 5).

  On the other hand, from the results shown in Table 3, in Comparative Examples 1 to 4, the polymer (A) was mixed and dissolved together with the polymerizable monomer (b) constituting the polymer (B) as in the examples, and then polymerized. Since the monomer (b) was not polymerized, a reverse phase separation structure was formed, a dense network structure was not formed, and the adhesive properties were not satisfactory.

DESCRIPTION OF SYMBOLS 1 Dispersed phase 2 Continuous phase 10 Adhesive layer 20 Continuous phase (The polymer (A) is a main component)
30 Dispersed phase (mainly polymer (B))
(A) Polymer (A) (Base polymer)
(B) Polymer (B)
(B) Polymerizable monomer (b)

Claims (3)

A pressure-sensitive adhesive layer containing a polymer (A) and a polymer (B), wherein a continuous phase containing the polymer (A) and a dispersed phase containing the polymer (B) are formed,
The pressure-sensitive adhesive layer is formed by polymerizing a pressure-sensitive adhesive composition containing the polymer (A) and a polymerizable monomer (b) constituting the monomer unit of the polymer (B) with radiation energy, thereby continuously A pressure-sensitive adhesive layer forming a phase and the dispersed phase.   A pressure-sensitive adhesive sheet comprising the pressure-sensitive adhesive layer according to claim 1. It is a manufacturing method of the adhesive layer according to claim 1,
A step of preparing a pressure-sensitive adhesive composition by mixing the polymer (A) and a polymerizable monomer (b) constituting a monomer unit of the polymer (B);
The process of preparing the adhesive layer which forms the continuous phase containing the said polymer (A), and the dispersed phase containing the said polymer (B) by superposing | polymerizing the said adhesive composition by radiation energy. And a method for producing a pressure-sensitive adhesive layer.

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