JP5523365B2 - Adhesive composition, adhesive sheet and surface protective film - Google Patents

Description

The present invention relates to an antistatic pressure-sensitive adhesive composition, and an antistatic pressure-sensitive adhesive sheet and a surface protective film which are formed into a sheet form or a tape form using the same.

The pressure-sensitive adhesive sheets comprising the antistatic pressure-sensitive adhesive composition of the present invention are suitably used for plastic products and the like that are likely to generate static electricity. In particular, it is useful as an antistatic pressure-sensitive adhesive sheet and a surface protective film used in applications that dislike static electricity such as electronic devices.

The surface protective film is generally used for the purpose of sticking to a body to be protected through an adhesive applied to the side of the protective film and preventing scratches and dirt generated during processing and transportation of the body to be protected. For example, a panel of a liquid crystal display is formed by attaching an optical member such as a polarizing plate or a wave plate to a liquid crystal cell via an adhesive. In these optical members to be bonded to the liquid crystal cell, a protective film is bonded via an adhesive for the purpose of preventing scratches and dirt.

Then, the protective film is peeled off and removed at a stage where the protective film is no longer necessary, for example, by bonding the optical member to the liquid crystal cell. In general, since a protective film and an optical member are made of a plastic material, they have high electrical insulation and generate static electricity during friction and peeling. Accordingly, static electricity is generated when the protective film is peeled off from the optical member such as a polarizing plate. If a voltage is applied to the liquid crystal while static electricity remains, the alignment of the liquid crystal molecules is lost or the panel is damaged. Therefore, in order to prevent such problems, the surface protective film is subjected to various antistatic treatments.

For example, a method is disclosed in which one or more surfactants are added to an adhesive and the surfactant is transferred from the adhesive to an adherend to prevent electrification (see, for example, Patent Document 1). However, this invention is an invention in which a surfactant is bleed on the surface of an adhesive and transferred to an adherend, and when applied to a protective film, it is applied to the adherend in order to exhibit sufficient antistatic properties. Contamination is inevitable. In addition, in consideration of contamination of the adherend, when the amount of the surfactant added is reduced, sufficient antistatic properties cannot be obtained. Therefore, when a pressure-sensitive adhesive to which a low molecular surfactant is added is applied to the protective film for an optical member, it is difficult to develop sufficient antistatic properties without impairing the optical properties of the optical member.

Further, a method is disclosed in which an antistatic agent comprising a polyether polyol and an alkali metal salt is added to an acrylic pressure-sensitive adhesive to suppress bleeding of the antistatic agent on the surface of the pressure-sensitive adhesive (for example, see Patent Document 2). . However, alkali metal salts are highly corrosive, and if the amount added is large, the metal may be corroded if the adhesive surface directly touches the metal. In particular, as a use application of the protective film for optical members, there are many examples in which the outer peripheral portion of the optical member is applied to a liquid crystal module fixed with a metal fixing frame called stainless steel or aluminum called “bezel”. In applications, the possibility of alteration of the “bezel” due to corrosion by the above-mentioned adhesive component was found, and there were restrictions on application.

JP-A-9-165460 JP-A-6-128539

In light of such circumstances, the present invention can prevent the charging of an adherend that is not antistatic when peeled, reduces the contamination of the adherend, and reduces the occurrence of corrosion on the metal. It is an object to provide an article, an antistatic pressure-sensitive adhesive sheet using the same, and a surface protective film.

As a result of intensive studies to solve the above problems, the present inventors have found that the above object can be achieved by the pressure-sensitive adhesive composition shown below, and have completed the present invention.

That is, the pressure-sensitive adhesive composition of the present invention is a pressure-sensitive adhesive composition comprising an ionic liquid, an alkali metal salt, and a polymer having a glass transition temperature Tg of 0 ° C. or less as a base polymer, The alkali metal salt is contained in an amount of 0.005 parts by weight or more and less than 0.1 parts by weight with respect to parts by weight.

Further, the ionic liquid in the present invention refers to a molten salt (ionic compound) that is liquid at room temperature (25 ° C.).

According to the present invention, by using the above ionic liquid and alkali metal salt as an antistatic agent, the contamination of the adherend is reduced, the occurrence of corrosion on the metal is small, and the adhesive has excellent antistatic properties. An agent composition is obtained. Although the details of the reason why the contamination of the adherend and the occurrence of corrosion on the metal are suppressed are not clear, the combined use of an ionic liquid and an alkali metal salt to balance compatibility with the base polymer, conductivity, etc. It is presumed that it contributes to a good interaction, can exhibit good antistatic properties with a small addition amount, and can suppress contamination of the protected object and can be combined with good charging properties. Further, since the ionic liquid is preferably in a liquid state at room temperature, it can be easily added to, dispersed in, or dissolved in the pressure-sensitive adhesive as compared with a solid salt. Further, since the ionic liquid has no vapor pressure (non-volatile), it has a characteristic that the antistatic property is continuously obtained without disappearing with time.

The pressure-sensitive adhesive composition preferably further contains a surfactant. By using a surfactant, the compatibility of the ionic liquid, alkali metal salt, and base polymer is further improved, bleeding of the adhesive composition to the adherend is suppressed, and low-contamination and low-corrosive adhesion. It becomes an agent composition.

In the above, it is preferable that the ionic liquid is at least one of a nitrogen-containing onium salt, a sulfur-containing onium salt, and a phosphorus-containing onium salt. In particular, the ionic liquid preferably contains one or more cations represented by the following general formulas (A) to (D). An ionic liquid having these cations provides a further excellent antistatic ability.

[R _a in the formula (A) represents a hydrocarbon group having 4 to 20 carbon atoms and may include a hetero atom, and R _b and R _c may be the same or different, and may be hydrogen or _C 1 to _C 16. Represents a hydrocarbon group and may contain heteroatoms. However, when the nitrogen atom contains a double bond, there is no R _c . ]
[R _d in the formula (B) represents a hydrocarbon group having 2 to 20 carbon atoms and may contain a hetero atom, and R _e , R _f , and R _g are the same or different and represent hydrogen or carbon number. Represents 1 to 16 hydrocarbon groups and may contain heteroatoms. ]
[R _h in the formula (C) represents a hydrocarbon group having 2 to 20 carbon atoms, and may contain a hetero atom, and R _i , R _j , and R _k may be the same or different and represent hydrogen or carbon number. Represents 1 to 16 hydrocarbon groups and may contain heteroatoms. ]
[Z in Formula (D) represents a nitrogen, sulfur, or phosphorus atom, and R ₁ , R _m , R _n , and R _o are the same or different and represent a hydrocarbon group having 1 to 20 carbon atoms. And may contain heteroatoms. However, when Z is a sulfur atom, there is no _Ro . ]

The alkali metal salt is preferably a lithium salt. By using a lithium salt having high dissociation properties, excellent charging characteristics can be expressed with a small amount of addition.

The surfactant is preferably a surfactant having an ethylene oxide group. By using a surfactant having an ethylene oxide group, compatibility with the ionic liquid and the base polymer is improved, bleeding to the adherend is suppressed, and a pressure-sensitive adhesive composition with low contamination and low corrosivity is obtained. .

Furthermore, the polymer having a glass transition temperature Tg of 0 ° C. or lower is preferably a (meth) acrylic polymer having as a main component at least one (meth) acrylate having an alkyl group having 1 to 14 carbon atoms. These (meth) acrylic polymers provide a good balance of compatibility with the ionic liquid and the base polymer, and can sufficiently maintain the adhesive properties.

Here, the (meth) acrylic polymer in the present invention refers to an acrylic polymer and / or a methacrylic polymer, and (meth) acrylate refers to an acrylate and / or methacrylate.

On the other hand, the pressure-sensitive adhesive layer of the present invention is characterized by cross-linking the above pressure-sensitive adhesive composition. By appropriately adjusting the structural unit, the structural ratio, the selection of the crosslinking agent, the addition ratio, and the like of the (meth) acrylic polymer to perform crosslinking, pressure-sensitive adhesive sheets having more excellent heat resistance, weather resistance, and the like can be obtained.

The pressure-sensitive adhesive sheets of the present invention are characterized by having a pressure-sensitive adhesive layer formed by crosslinking the pressure-sensitive adhesive composition described above on one or both sides of a support. According to the pressure-sensitive adhesive sheets of the present invention, since the pressure-sensitive adhesive composition of the present invention that exhibits the above-described effects is used, it is possible to prevent the adherend that is not antistatic when peeled off, to the adherend. The pressure-sensitive adhesive sheets can be made excellent in adhesion reliability with reduced contamination.

Furthermore, the surface protective film of the present invention is characterized by having a pressure-sensitive adhesive layer formed by crosslinking the pressure-sensitive adhesive composition described above on one or both sides of a support. According to the surface protective film of the present invention, since the pressure-sensitive adhesive composition of the present invention having the above-described effects is used, it is possible to prevent the adherend that is not antistatic when peeled off, and to adhere to the adherend. It is possible to obtain a surface protective film with reduced adhesion and excellent adhesion reliability.

Schematic configuration diagram of potential measurement unit used for measurement of peeling voltage in Examples etc.

The pressure-sensitive adhesive composition of the present invention is a pressure-sensitive adhesive composition comprising an ionic liquid, an alkali metal salt, and a polymer having a glass transition temperature Tg of 0 ° C. or less as a base polymer, and 100 parts by weight of the base polymer On the other hand, it is characterized by containing 0.005 part by weight or more and less than 0.1 part by weight of the alkali metal salt.

As the ionic liquid, a nitrogen-containing onium salt, a sulfur-containing onium salt, or a phosphorus-containing onium salt is preferably used, and is represented by the following general formulas (A) to (D) for the reason that particularly excellent antistatic ability is obtained. What consists of an organic cation component and an anion component is used preferably.

[R _a in the formula (A) represents a hydrocarbon group having 4 to 20 carbon atoms and may include a hetero atom, and R _b and R _c may be the same or different, and may be hydrogen or _C 1 to _C 16. Represents a hydrocarbon group and may contain heteroatoms. However, when the nitrogen atom contains a double bond, there is no R _c . ]
[R _d in the formula (B) represents a hydrocarbon group having 2 to 20 carbon atoms and may contain a hetero atom, and R _e , R _f , and R _g are the same or different and represent hydrogen or carbon number. Represents 1 to 16 hydrocarbon groups and may contain heteroatoms. ]
[R _h in the formula (C) represents a hydrocarbon group having 2 to 20 carbon atoms, and may contain a hetero atom, and R _i , R _j , and R _k may be the same or different and represent hydrogen or carbon number. Represents 1 to 16 hydrocarbon groups and may contain heteroatoms. ]
[Z in Formula (D) represents a nitrogen, sulfur, or phosphorus atom, and R ₁ , R _m , R _n , and R _o are the same or different and represent a hydrocarbon group having 1 to 20 carbon atoms. And may contain heteroatoms. However, when Z is a sulfur atom, there is no _Ro . ]

Examples of the cation represented by the formula (A) include a pyridinium cation, a piperidinium cation, a pyrrolidinium cation, a cation having a pyrroline skeleton, and a cation having a pyrrole skeleton. Specific examples include, for example, 1-ethylpyridinium cation, 1-butylpyridinium cation, 1-hexylpyridinium cation, 1-butyl-3-methylpyridinium cation, 1-butyl-4-methylpyridinium cation, 1-hexyl. -3-methylpyridinium cation, 1-butyl-3,4-dimethylpyridinium cation, 1,1-dimethylpyrrolidinium cation, 1-ethyl-1-methylpyrrolidinium cation, 1-methyl-1-propylpyrrolidi Examples thereof include a nium cation, a 2-methyl-1-pyrroline cation, a 1-ethyl-2-phenylindole cation, a 1,2-dimethylindole cation, and a 1-ethylcarbazole cation.

Examples of the cation represented by the formula (B) include an imidazolium cation, a tetrahydropyrimidinium cation, and a dihydropyrimidinium cation. Specific examples include, for example, 1,3-dimethylimidazolium cation, 1,3-diethylimidazolium cation, 1-ethyl-3-methylimidazolium cation, 1-butyl-3-methylimidazolium cation, and 1-helium. Xyl-3-methylimidazolium cation, 1-octyl-3-methylimidazolium cation, 1-decyl-3-methylimidazolium cation, 1-dodecyl-3-methylimidazolium cation, 1-tetradecyl-3-methylimidazole Cation, 1,2-dimethyl-3-propylimidazolium cation, 1-ethyl-2,3-dimethylimidazolium cation, 1-butyl-2,3-dimethylimidazolium cation, 1-hexyl-2,3 -Dimethylimidazolium cation, 1,3-dimethyl -1,4,5,6-tetrahydropyrimidinium cation, 1,2,3-trimethyl-1,4,5,6-tetrahydropyrimidinium cation, 1,2,3,4-tetramethyl-1, 4,5,6-tetrahydropyrimidinium cation, 1,2,3,5-tetramethyl-1,4,5,6-tetrahydropyrimidinium cation, 1,3-dimethyl-1,4-dihydropyrimidi Cation, 1,3-dimethyl-1,6-dihydropyrimidinium cation, 1,2,3-trimethyl-1,4-dihydropyrimidinium cation, 1,2,3-trimethyl-1,6-dihydro Pyrimidinium cation, 1,2,3,4-tetramethyl-1,4-dihydropyrimidinium cation, 1,2,3,4-tetramethyl-1,6-dihydropyrimidini Such as Mukachion, and the like.

Examples of the cation represented by the formula (C) include a pyrazolium cation and a pyrazolinium cation. Specific examples include 1-methylpyrazolium cation, 3-methylpyrazolium cation, 1-ethyl-2-methylpyrazolinium cation and the like.

As the cation represented by the formula (D), for example, a tetraalkylammonium cation, a trialkylsulfonium cation, a tetraalkylphosphonium cation, or a part of the alkyl group is substituted with an alkenyl group, an alkoxyl group, or an epoxy group. And so on.

Specific examples include, for example, tetramethylammonium cation, tetraethylammonium cation, tetrapropylammonium cation, tetrabutylammonium cation, tetrapentylammonium cation, tetrahexylammonium cation, tetraheptylammonium cation, trimethylheptylammonium cation, trimethyldecylammonium cation , Triethylmethylammonium cation, triethylpropylammonium cation, triethylpentylammonium cation, triethylhexylammonium cation, triethylheptylammonium cation, tributylethylammonium cation, tripentylbutylammonium cation, trihexylmethylammonium cation, Lihexylpentylammonium cation, triheptylmethylammonium cation, triheptylhexylammonium cation, trioctylmethylammonium cation, glycidyltrimethylammonium cation, diallyldimethylammonium cation, N, N-dimethyl-N, N-dipropylammonium cation, N , N-dimethyl-N, N-dihexylammonium cation, N, N-dipropyl-N, N-dihexylammonium cation, N, N-dimethyl-N-ethyl-N-propylammonium cation, N, N-dimethyl-N -Ethyl-N-butylammonium cation, N, N-dimethyl-N-ethyl-N-pentylammonium cation, N, N-dimethyl-N-ethyl-N-hexylammonium cation, N, N-dimethyl-N- To ethyl-N- Ptyl ammonium cation, N, N-dimethyl-N-ethyl-N-nonyl ammonium cation, N, N-dimethyl-N-propyl-N-butyl ammonium cation, N, N-dimethyl-N-propyl-N-pentyl ammonium Cation, N, N-dimethyl-N-propyl-N-hexylammonium cation, N, N-dimethyl-N-propyl-N-heptylammonium cation, N, N-dimethyl-N-butyl-N-hexyl Ammonium cation, N, N-dimethyl-N-butyl-N-heptylammonium cation, N, N-dimethyl-N-pentyl-N-hexylammonium cation, N, N-dimethyl-N-hexyl-N- Heptylammonium cation, N, N-diethyl-N-methyl-N-propylammonium cation, N, N-diethyl-N-methyl-N-pentylammo Cation, N, N-diethyl-N-methyl-N-heptylammonium cation, N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium cation, N, N-diethyl-N-propyl- N-pentylammonium cation, N, N-dipropyl-N-methyl-N-ethylammonium cation, N, N-dipropyl-N-methyl-N-pentylammonium cation, N, N-dipropyl-N-butyl-N- Hexyl ammonium cation, N, N-dibutyl-N-methyl-N-pentyl ammonium cation, N, N-dibutyl-N-methyl-N-hexyl ammonium cation, N-methyl-N-ethyl-N-propyl- N-pentylammonium cation, trimethylsulfonium cation, triethylsulfonium cation, tributylsulfonium cation, Trihexylsulfonium cation, dimethyldecylsulfonium cation, diethylmethylsulfonium cation, dibutylethylsulfonium cation, tetramethylphosphonium cation, tetraethylphosphonium cation, tetrabutylphosphonium cation, tetrapentylphosphonium cation, tetrahexylphosphonium cation, tetraheptylphosphonium cation, tetra Examples thereof include octylphosphonium cation, trimethyldecylphosphonium cation, triethylmethylphosphonium cation, and tributylethylphosphonium cation. Among them, trimethylheptylammonium cation, trimethyldecylammonium cation, triethylmethylammonium cation, triethylpropylammonium cation, triethylpentylammonium cation, triethylhexylammonium cation, triethylheptylammonium cation, tributylethylammonium cation, tripentylbutylammonium cation, trihexyl Methylammonium cation, trihexylpentylammonium cation, triheptylmethylammonium cation, triheptylhexylammonium cation, trioctylmethylammonium cation, glycidyltrimethylammonium cation, N, N-dimethyl-N-ethyl-N-propylammonium cation, N, N-dimethyl-N-ethyl-N-butylammonium cation, N, N-dimethyl-N-ethyl-N-pentylammonium cation, N, N-dimethyl-N-ethyl-N-hexylammonium cation, N, N-dimethyl-N-ethyl-N-heptylammonium cation, N, N-dimethyl-N-ethyl-N-nonylammonium cation, N, N-dimethyl-N-propyl-N-butylammonium cation, N , N-dimethyl-N-propyl-N-pentylammonium cation, N, N-dimethyl-N-propyl-N-hexylammonium cation, N, N-dimethyl-N-propyl-N-heptylammonium cation, N , N-dimethyl-N-butyl-N-hexylammonium cation, N, N-dimethyl-N-butyl-N-heptylammonium cation, N, N-dimethyl-N-pe Cyl-N-hexylammonium cation, N, N-dimethyl-N-hexyl-N-heptylammonium cation, N, N-diethyl-N-methyl-N-propylammonium cation, N, N-diethyl-N -Methyl-N-pentylammonium cation, N, N-diethyl-N-methyl-N-heptylammonium cation, N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium cation, N, N -Diethyl-N-propyl-N-pentylammonium cation, N, N-dipropyl-N-methyl-N-ethylammonium cation, N, N-dipropyl-N-methyl-N-pentylammonium cation, N, N-dipropyl -N-butyl-N-hexylammonium cation, N, N-dibutyl-N-methyl-N-pentylammonium cation, N, N-dibutyl-N- Asymmetric tetraalkylammonium cations such as til-N-hexylammonium cation, N-methyl-N-ethyl-N-propyl-N-pentylammonium cation, dimethyldecylsulfonium cation, diethylmethylsulfonium cation, dibutylethylsulfonium cation, etc. Asymmetric tetraalkylphosphonium cations such as trimethylsulfonium cation, trimethyldecylphosphonium cation, triethylmethylphosphonium cation, and tributylethylphosphonium cation are preferably used.

On the other hand, the anion component is not particularly limited as long as it satisfies that it becomes an ionic liquid. For example, Cl ⁻ , Br ⁻ , I ⁻ , AlCl ₄ ⁻ , Al ₂ Cl ₇ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , ClO ₄ ⁻ , NO ₃ ⁻ , CH ₃ COO ⁻ , CF ₃ COO ⁻ , CH ₃ SO ₃ ⁻ , CF ₃ SO ₃ ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ , (CF ₃ SO ₂ ) ₃ C ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ , NbF ₆ ⁻ , TaF ₆ ⁻ , F (HF) _n ⁻ , (CN) ₂ N ⁻ , C ₄ F ₉ SO ₃ ⁻ , (C ₂ F ₅ SO ₂ ) ₂ N ⁻ , C ₃ F ₇ COO ⁻ , (CF ₃ SO ₂ ) (CF ₃ CO) N ⁻ or the like is used. Among these, an anion component containing a fluorine atom is particularly preferably used since an ionic compound having a low melting point can be obtained.

Specific examples of the ionic liquid used in the present invention are appropriately selected from the combination of the cation component and the anion component, and include 1-butylpyridinium tetrafluoroborate, 1-butylpyridinium hexafluorophosphate, 1-butyl- 3-methylpyridinium tetrafluoroborate, 1-butyl-3-methylpyridinium trifluoromethanesulfonate, 1-butyl-3-methylpyridinium bis (trifluoromethanesulfonyl) imide, 1-butyl-3-methylpyridinium bis (pentafluoroethanesulfonyl) ) Imido, 1-hexylpyridinium tetrafluoroborate, 2-methyl-1-pyrroline tetrafluoroborate, 1-ethyl-2-phenylindole tetrafluoroborate, 1,2-dimethyli Dole tetrafluoroborate, 1-ethylcarbazole tetrafluoroborate, 1-ethyl-3-methylimidazolium tetrafluoroborate, 1-ethyl-3-methylimidazolium acetate, 1-ethyl-3-methylimidazolium trifluoroacetate, 1-ethyl-3-methylimidazolium heptafluorobutyrate, 1-ethyl-3-methylimidazolium trifluoromethanesulfonate, 1-ethyl-3-methylimidazolium perfluorobutanesulfonate, 1-ethyl-3-methylimidazolium di Cyanamide, 1-ethyl-3-methylimidazolium bis (trifluoromethanesulfonyl) imide, 1-ethyl-3-methylimidazolium bis (pentafluoroethanesulfonyl) imide, 1-ethyl 3-methylimidazolium tris (trifluoromethanesulfonyl) methide, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium trifluoro Acetate, 1-butyl-3-methylimidazolium heptafluorobutyrate, 1-butyl-3-methylimidazolium trifluoromethanesulfonate, 1-butyl-3-methylimidazolium perfluorobutanesulfonate, 1-butyl-3-methylimidazole Bis (trifluoromethanesulfonyl) imide, 1-hexyl-3-methylimidazolium bromide, 1-hexyl-3-methylimidazolium chloride, 1-hexyl-3-methylimidazolium 1-hexyl-3-methylimidazolium hexafluorophosphate, 1-hexyl-3-methylimidazolium trifluoromethanesulfonate, 1-octyl-3-methylimidazolium tetrafluoroborate, 1-octyl- 3-methylimidazolium hexafluorophosphate, 1-hexyl-2,3-dimethylimidazolium tetrafluoroborate, 1,2-dimethyl-3-propylimidazolium bis (trifluoromethanesulfonyl) imide, 1-methylpyrazolium Tetrafluoroborate, 3-methylpyrazolium tetrafluoroborate, tetrahexylammonium bis (trifluoromethanesulfonyl) imide, diallyldimethylammonium tetrafluoroborate, diary Dimethylammonium trifluoromethanesulfonate, diallyldimethylammonium bis (trifluoromethanesulfonyl) imide, diallyldimethylammonium bis (pentafluoroethanesulfonyl) imide, N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium tetrafluoro Borate, N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium trifluoromethanesulfonate, N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium bis (trifluoromethanesulfonyl) Imido, N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium bis (pentafluoroethanesulfonyl) imide, glycidyltrimethylammonium trifluorometa Sulfonate, glycidyltrimethylammonium bis (trifluoromethanesulfonyl) imide, glycidyltrimethylammonium bis (pentafluoroethanesulfonyl) imide, 1-butylpyridinium (trifluoromethanesulfonyl) trifluoroacetamide, 1-butyl-3-methylpyridinium (trifluoromethanesulfonyl) ) Trifluoroacetamide, 1-ethyl-3-methylimidazolium (trifluoromethanesulfonyl) trifluoroacetamide, N, N-diethyl-N-methyl-N- (2-methoxyethyl) ammonium (trifluoromethanesulfonyl) trifluoroacetamide , Diallyldimethylammonium (trifluoromethanesulfonyl) trifluoroacetamide, glycidyltrimethyl Ammonium (trifluoromethanesulfonyl) trifluoroacetamide, N, N-dimethyl-N-ethyl-N-propylammonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl-N-ethyl-N-butylammonium bis (trifluoromethane Sulfonyl) imide, N, N-dimethyl-N-ethyl-N-pentylammonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl-N-ethyl-N-hexylammonium bis (trifluoromethanesulfonyl) imide, N , N-dimethyl-N-ethyl-N-heptylammonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl-N-ethyl-N-nonylammonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl Ru-N, N-dipropylammonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl-N-propyl-N-butylammonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl-N-propyl-N -Pentylammonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl-N-propyl-N-hexylammonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl-N-propyl-N-heptylammonium bis (trifluoro) Lomethanesulfonyl) imide, N, N-dimethyl-N-butyl-N-hexylammonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl-N-butyl-N-heptylammonium bis (trifluoromethanesulfonyl) N, N-dimethyl-N-pentyl-N-hexylammonium bis (trifluoromethanesulfonyl) imide, N, N-dimethyl-N, N-dihexylammonium bis (trifluoromethanesulfonyl) imide, trimethylheptylammonium bis (trifluoro) (Romethanesulfonyl) imide, N, N-diethyl-N-methyl-N-propylammonium bis (trifluoromethanesulfonyl) imide, N, N-diethyl-N-methyl-N-pentylammonium bis (trifluoromethanesulfonyl) imide, N , N-diethyl-N-methyl-N-heptylammonium bis (trifluoromethanesulfonyl) imide, N, N-diethyl-N-propyl-N-pentylammonium bis (trifluoromethanesulfonyl) imide, Triethylpropylammonium bis (trifluoromethanesulfonyl) imide, triethylpentylammonium bis (trifluoromethanesulfonyl) imide, triethylheptylammonium bis (trifluoromethanesulfonyl) imide, N, N-dipropyl-N-methyl-N-ethylammonium bis (trifluoro) Romethanesulfonyl) imide, N, N-dipropyl-N-methyl-N-pentylammonium bis (trifluoromethanesulfonyl) imide, N, N-dipropyl-N-butyl-N-hexylammonium bis (trifluoromethanesulfonyl) imide, N, N-dipropyl-N, N-dihexylammonium bis (trifluoromethanesulfonyl) imide, N, N-dibutyl-N-methyl-N-pentylammonium Bis (trifluoromethanesulfonyl) imide, N, N-dibutyl-N-methyl-N-hexylammonium bis (trifluoromethanesulfonyl) imide, trioctylmethylammonium bis (trifluoromethanesulfonyl) imide, N-methyl-N-ethyl- And N-propyl-N-pentylammonium bis (trifluoromethanesulfonyl) imide.

A commercially available ionic liquid as described above may be used, but it can also be synthesized as follows. The method for synthesizing the ionic liquid is not particularly limited as long as the target ionic liquid is obtained. In general, the document “ionic liquids—the forefront and future of development” [CMC Publishing Co., Ltd.] A halide method, a hydroxide method, an acid ester method, a complex formation method, a neutralization method and the like as described in “Issuance” are used.

The synthesis method of the halide method, hydroxide method, acid ester method, complex formation method, and neutralization method will be described below using a nitrogen-containing onium salt as an example. Other sulfur-containing onium salts, phosphorus-containing onium salts, etc. This ionic liquid can also be obtained by the same method.

The halide method is a method carried out by reactions as shown in the following formulas (1) to (3). First, a tertiary amine and an alkyl halide are reacted to obtain a halide (reaction formula (1), and chlorine, bromine, and iodine are used as the halogen).

Acid (HA) or salt having the anion structure (A ⁻ ) of the ionic liquid intended for the obtained halide (MA and M are cations that form a salt with the desired anion such as ammonium, lithium, sodium, potassium, etc.) ) To obtain the desired ionic liquid (R ₄ NA).

The hydroxide method is a method performed by reactions as shown in (4) to (8). First, halide (R ₄ NX) is subjected to ion exchange membrane electrolysis (reaction formula (4)), OH type ion exchange resin method (reaction formula (5)) or reaction with silver oxide (Ag ₂ O) (reaction formula ( 6)) to obtain a hydroxide (R ₄ NOH) (chlorine, bromine and iodine are used as the halogen).

The target ionic liquid (R ₄ NA) can be obtained from the obtained hydroxide using the reactions of the reaction formulas (7) to (8) in the same manner as the halogenation method.

The acid ester method is a method performed by reactions as shown in (9) to (11). First, a tertiary amine (R ₃ N) is reacted with an acid ester to obtain an acid ester product (Reaction Formula (9)). As the acid ester, inorganic acids such as sulfuric acid, sulfurous acid, phosphoric acid, phosphorous acid, and carbonic acid And esters of organic acids such as esters, methanesulfonic acid, methylphosphonic acid, formic acid, etc.).

The target ionic liquid (R ₄ NA) is obtained from the obtained acid ester using the reactions of the reaction formulas (10) to (11) in the same manner as the halogenation method. Further, by using methyl trifluoromethanesulfonate, methyl trifluoroacetate or the like as the acid ester, an ionic liquid can be directly obtained.

The complex formation method is a method performed by reactions as shown in (12) to (15). First, a quaternary ammonium halide (R ₄ NX), a quaternary ammonium hydroxide (R ₄ NOH), a quaternary ammonium carbonate ester (R ₄ NOCO ₂ CH ₃ ) or the like is added to hydrogen fluoride (HF) or Reaction with ammonium fluoride (NH ₄ F) gives a quaternary ammonium fluoride salt (reaction formulas (12) to (14)).

An ionic liquid can be obtained by complexing the obtained quaternary ammonium fluoride with a fluoride such as BF ₃ , AlF ₃ , PF ₅ , ASF ₅ , SbF ₅ , NbF ₅ , TaF ₅ (reaction) Formula (15)).

The neutralization method is a method performed by a reaction as shown in (16). Tertiary amine and HBF ₄ , HPF ₆ , CH ₃ COOH, CF ₃ COOH, CF ₃ SO ₃ H, (CF ₃ SO ₂ ) ₂ NH, (CF ₃ SO ₂ ) ₃ CH, (C ₂ F ₅ SO ₂ ) ₂ It can be obtained by reacting with an organic acid such as NH.

R in the above formulas (1) to (16) represents hydrogen or a hydrocarbon group having 1 to 20 carbon atoms, and may contain a hetero atom.

The blending amount of the ionic liquid cannot be defined unconditionally because it varies depending on the compatibility of the acrylic polymer to be used and the ionic liquid, but is generally 0.01 to 100 parts by weight of the base polymer. 10 parts by weight is preferable, 0.03 to 7 parts by weight is more preferable, and 0.05 to 5 parts by weight is most preferable. When the amount is less than 0.01 parts by weight, sufficient antistatic properties cannot be obtained, and when the amount exceeds 10 parts by weight, contamination of the adherend tends to increase.

Examples of the alkali metal salt used in the present invention include a metal salt composed of lithium, sodium and potassium. Specifically, for example, a cation composed of Li ⁺ , Na ⁺ and K ⁺ , Cl ⁻ , Br ⁻ , I ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , SCN ⁻ , ClO ₄ ⁻ , CF ₃ SO ₃ ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ , (C ₂ F ₅ SO ₂ ) ₂ N ⁻ , (CF ₃ SO _{2) 3} C ^- is preferably used comprised a metal salt from the recognized anions. Among them, LiBr, LiI, LiBF ₄ , LiPF ₆ , LiSCN, LiClO ₄ , LiCF ₃ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, Li (C ₂ F ₅ SO ₂ ) ₂ N, Li (CF ₃ SO ₂ ) A lithium salt such as ₃ C is preferably used. These alkali metal salts may be used alone or in combination of two or more.

About the compounding quantity of the alkali metal salt used in the said adhesive composition, 0.005 weight part or more and less than 0.1 weight part of alkali metal salt are mix | blended with respect to 100 weight part of (meth) acrylic-type copolymers. It is preferable. Furthermore, it is preferable to mix | blend 0.005-0.09 weight part, and it is more preferable to mix | blend 0.005-0.08 weight part. If the amount is less than 0.005 parts by weight, sufficient charging characteristics may not be obtained. On the other hand, if the amount is more than 0.1 parts by weight, contamination of the protected body tends to increase, which is not preferable.

In the present invention, a polymer having a glass transition temperature Tg of 0 ° C. or lower is used as the base polymer, preferably Tg is −100 ° C. to −5 ° C., more preferably Tg is −80 ° C. to −10 ° C. . When the glass transition temperature Tg is higher than 0 ° C., it may be difficult to obtain sufficient adhesive force.

Such polymers include acrylic polymers, natural rubber, styrene-isoprene-styrene block copolymers (SIS) having one or more of (meth) acrylates having an alkyl group having 1 to 14 carbon atoms as main components. Block copolymer), styrene-butadiene-styrene block copolymer (SBS block copolymer), styrene-ethylene-butylene-styrene block copolymer (SEBS block copolymer), styrene-butadiene rubber, polybutadiene, poly Polymers generally applied as the polymer of the pressure-sensitive adhesive such as isoprene, polyisobutylene, butyl rubber, chloroprene rubber and silicone rubber are listed.

Among these, the main component is one or more of (meth) acrylates having an alkyl group having 1 to 14 carbon atoms because a balance of compatibility with an ionic liquid and excellent adhesive properties can be obtained. Acrylic polymers are preferably used.

As an acrylic polymer mainly composed of one or more of (meth) acrylates having 1 to 14 carbon atoms, the (meth) acrylates having 1 to 14 carbon atoms are included. An acrylic polymer mainly composed of a monomer containing 50 to 100% by weight of one kind or two or more kinds is used.

Specific examples of the (meth) acrylate having an alkyl group having 1 to 14 carbon atoms include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, and s-butyl (meth) acrylate. , T-butyl (meth) acrylate, isobutyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, n-nonyl (meth) acrylate , Isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, n-dodecyl (meth) acrylate, n-tridecyl (meth) acrylate, n-tetradecyl (meth) acrylate, and the like.

Especially, as an acrylic polymer used for the surface protective film of the present invention, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, isooctyl (meth) acrylate, n-nonyl (meth) 6 carbon atoms such as acrylate, isononyl (meth) acrylate, n-decyl (meth) acrylate, isodecyl (meth) acrylate, n-dodecyl (meth) acrylate, n-tridecyl (meth) acrylate, n-tetradecyl (meth) acrylate An acrylic polymer composed of (meth) acrylate having -14 alkyl groups is preferably used. By using an acrylic polymer composed of (meth) acrylate having an alkyl group having 6 to 14 carbon atoms, it becomes easy to control the adhesive force to the adherend to be low, and has excellent removability. It becomes.

As other components, the Tg is 0 ° C. or lower (usually −100 ° C. or higher) for the reason that it is easy to balance the adhesive performance, and the sulfonic acid group-containing monomer, phosphoric acid group-containing monomer, and cyano group-containing monomer are appropriately used. , Vinyl ester, aromatic vinyl compound and other cohesive strength / heat resistance improving components, carboxyl group-containing monomers, acid anhydride group-containing monomers, hydroxyl group-containing monomers, amide group-containing monomers, amino group-containing monomers, imide group-containing A component having a functional group that functions as an adhesive strength improvement or crosslinking base point, such as a monomer, an epoxy group-containing monomer, or a vinyl ether, can be used. Other components may be used alone or in combination of two or more.

However, when (meth) acrylate having an acid functional group such as a carboxyl group, a sulfonic acid group, or a phosphoric acid group is used, it is preferable to adjust the acid value of the acrylic polymer to be 29 or less. When the acid value of the acrylic polymer exceeds 29, the antistatic property tends to deteriorate.

The acid value can be adjusted by adjusting the amount of (meth) acrylate having an acid functional group, for example, an acrylic polymer obtained by copolymerizing 2-ethylhexyl acrylate and acrylic acid as an acrylic polymer having a carboxyl group. However, in this case, the acid value can be made 29 or less by adjusting acrylic acid to 3.7 parts by weight or less with respect to 100 parts by weight of the total amount of 2-ethylhexyl acrylate and acrylic acid. I can do it.

Examples of the sulfonic acid group-containing monomer include styrene sulfonic acid, allyl sulfonic acid, 2- (meth) acrylamide-2-methylpropane sulfonic acid, (meth) acrylamide propane sulfonic acid, sulfopropyl (meth) acrylate, and (meth). Examples include acryloyloxynaphthalene sulfonic acid and sodium vinyl sulfonate.

Examples of the phosphate group-containing monomer include 2-hydroxyethyl acryloyl phosphate.

Examples of the cyano group-containing monomer include acrylonitrile and methacrylonitrile.

Examples of vinyl esters include vinyl acetate, vinyl propionate, vinyl laurate, and the like.

Examples of the aromatic vinyl compound include styrene, chlorostyrene, chloromethyl styrene, α-methyl styrene, other substituted styrenes, and the like.

Examples of the carboxyl group-containing monomer include (meth) acrylic acid, carboxyethyl (meth) acrylate, carboxypentyl (meth) acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid.

Examples of the acid anhydride group-containing monomer include maleic anhydride, itaconic anhydride, and acid anhydride bodies of the above carboxyl group-containing monomers.

Examples of the hydroxyl group-containing monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl ( (Meth) acrylate, 10-hydroxydecyl (meth) acrylate, 12-hydroxylauryl (meth) acrylate, (4-hydroxymethylcyclohexyl) methyl acrylate, N-methylol (meth) acrylamide, vinyl alcohol, allyl alcohol, 2-hydroxyethyl Examples thereof include vinyl ether, 4-hydroxybutyl vinyl ether, diethylene glycol monovinyl ether and the like.

Examples of amide group-containing monomers include acrylamide, methacrylamide, diethyl acrylamide, N-vinyl pyrrolidone, N, N-dimethyl acrylamide, N, N-dimethyl methacrylamide, N, N-diethyl acrylamide, N, N-diethyl methacryl. Examples thereof include amide, N, N′-methylenebisacrylamide, N, N-dimethylaminopropyl acrylamide, N, N-dimethylaminopropyl methacrylamide and the like.

Examples of the amino group-containing monomer include aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, (meth) acryloylmorpholine, and the like.

Examples of the imide group-containing monomer include cyclohexylmaleimide, isopropylmaleimide, N-cyclohexylmaleimide, and itaconimide.

Examples of the epoxy group-containing monomer include glycidyl (meth) acrylate, methyl glycidyl (meth) acrylate, and allyl glycidyl ether.

Examples of vinyl ethers include methyl vinyl ether, ethyl vinyl ether, isobutyl vinyl ether, and the like.

The other polymerizable monomer components described above may be used alone or in admixture of two or more, but the total content is all structural units of the (meth) acrylic polymer The polymerizable monomer component is preferably 0.1 to 20 parts by weight and more preferably 0.5 to 10 parts by weight with respect to 100 parts by weight. By using the other polymerizable monomer components described above, good interaction with the ionic liquid and good adhesiveness can be appropriately adjusted.

The (meth) acrylic polymer used in the present invention has a weight average molecular weight of 100,000 to 5,000,000, preferably 200,000 to 4,000,000, more preferably 300,000 to 3,000,000. When the weight average molecular weight is smaller than 100,000, the adhesive force tends to be generated due to a decrease in the cohesive force of the pressure-sensitive adhesive composition. On the other hand, when the weight average molecular weight exceeds 5,000,000, the fluidity of the polymer is lowered, the wetting to the polarizing plate becomes insufficient, and it tends to cause peeling. A weight average molecular weight means what was obtained by measuring by GPC (gel permeation chromatography).

The acrylic polymer can be obtained by a polymerization method generally used as a synthesis method of an acrylic polymer, such as solution polymerization, emulsion polymerization, bulk polymerization, and suspension polymerization.

Further, the obtained acrylic polymer may be any of a random copolymer, a block copolymer, a graft copolymer, an alternating copolymer, and the like.

In the pressure-sensitive adhesive composition of the present invention, the contamination of the adherend is further reduced by adding a surfactant. The surfactant is preferably a surfactant having an ether group.

Specific examples of the surfactant having an ether group include, for example, polyoxyalkylene fatty acid esters, polyoxyalkylene sorbitan fatty acid esters, polyoxyalkylene sorbitol fatty acid esters, polyoxyalkylene alkyl ethers, polyoxyalkylene alkyl allyl. Nonionic surfactants such as ethers, polyoxyalkylene alkylphenyl ethers, polyoxyalkylene derivatives, polyoxyalkylene alkylamines, polyoxyalkylene alkylamine fatty acid esters, polyoxyalkylene alkyl ether sulfates, poly Oxyalkylene alkyl ether phosphates, polyoxyalkylene alkyl phenyl ether sulfates, polyoxyalkylene alkyl phenyl amines Anionic surfactants such as Berlin acid salts, cationic surfactants and zwitterionic surfactants having an alkylene oxide group. Moreover, you may have reactive substituents, such as a (meth) acryloyl group and an allyl group, in a molecule | numerator.

The surfactant in the present invention is more preferably a surfactant having an ethylene oxide group. Specific examples include, for example, polyoxyethylene fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene sorbitol fatty acid esters, polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, polyoxyethylene alkylphenyl Nonionic surfactants such as ethers, polyoxyethylene derivatives, polyoxyethylene alkylamines, polyoxyethylene alkylamine fatty acid esters, polyoxyethylene alkyl ether sulfates, polyoxyethylene alkyl ether phosphates Anionic surface actives such as polyoxyethylene alkylphenyl ether sulfates, polyoxyethylene alkylphenyl ether phosphates Agents, cationic surfactants and zwitterionic surfactants having an ethylene oxide group. Moreover, you may have reactive substituents, such as a (meth) acryloyl group and an allyl group, in a molecule | numerator.

The added mole number of the oxyalkylene unit of the surfactant having an alkylene oxide group is preferably 1 to 50, more preferably 2 to 40, from the viewpoint of interaction with the ionic liquid. The absence of an alkylene oxide group is not preferable because it is difficult to balance the compatibility with the ionic liquid and the base polymer and the bleed to the adherend tends to increase. On the other hand, when a surfactant having an added mole number of oxyalkylene units exceeding 50 is used, the ionic liquid is restrained by the alkylene oxide group and the antistatic property tends to be lowered, which is not preferable.

The above surfactants may be used alone or in combination, but the amount is preferably 0.01 to 10 parts by weight, preferably 0.05 to 5 parts by weight based on 100 parts by weight of the base polymer. Part is more preferred. When the blending amount is less than 0.01 parts by weight, it is difficult to obtain an effect of balancing antistatic properties and contamination, and when it exceeds 10 parts by weight, contamination on the adherend tends to increase. .

In the pressure-sensitive adhesive composition of the present invention, pressure-sensitive adhesive sheets having further excellent heat resistance and weather resistance can be obtained by appropriately crosslinking a base polymer, particularly an acrylic polymer. As specific means of the crosslinking method, it can react with a carboxyl group, a hydroxyl group, an amino group, an amide group, or the like appropriately included as a crosslinking base in an acrylic polymer such as an isocyanate compound, an epoxy compound, a melamine resin, or an aziridine compound. There is a method using a so-called crosslinking agent in which a compound having a group is added and reacted. Among these, an isocyanate compound and an epoxy compound are particularly preferably used mainly from the viewpoint of obtaining an appropriate cohesive force. These compounds may be used alone or in combination of two or more.

Among these, examples of the isocyanate compound include aromatic isocyanates such as tolylene diisocyanate and xylene diisocyanate, alicyclic isocyanates such as isophorone diisocyanate, and aliphatic isocyanates such as hexamethylene diisocyanate.

More specifically, examples of the isocyanate compound include lower aliphatic polyisocyanates such as butylene diisocyanate and hexamethylene diisocyanate, alicyclic isocyanates such as cyclopentylene diisocyanate, cyclohexylene diisocyanate, and isophorone diisocyanate. -Aromatic diisocyanates such as tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate, trimethylolpropane / tolylene diisocyanate trimer adduct (trade name Coronate L, manufactured by Nippon Polyurethane Industry Co., Ltd.), trimethylol Propane / hexamethylene diisocyanate trimer adduct (trade name Coronate HL, manufactured by Nippon Polyurethane Industry Co., Ltd.), hexamethylene diisocyanate Isocyanurate of (Nippon Polyurethane Industry Co., Ltd., trade name: Coronate HX), and the like, such as isocyanate adducts such as.

Examples of the epoxy compound include N, N, N ′, N′-tetraglycidyl m-xylenediamine (manufactured by Mitsubishi Gas Chemical Company, trade name: TETRAD-X) and 1,3-bis (N, N-diglycidylamino). Methyl) cyclohexane (trade name: TETRAD-C, manufactured by Mitsubishi Gas Chemical Company, Inc.).

Examples of the melamine-based resin include hexamethylol melamine.

Examples of the aziridine derivative include a commercial product name HDU, a product name TAZM, a product name TAZO (manufactured by Mutual Pharmaceutical Co., Ltd.), and the like. These compounds may be used alone or in combination of two or more.

The amount of these crosslinking agents to be used is appropriately selected depending on the balance with the (meth) acrylic polymer to be crosslinked, and further depending on the intended use as the pressure-sensitive adhesive sheet. In general, in order to obtain sufficient heat resistance due to the cohesive strength of the acrylic pressure-sensitive adhesive, it is preferably contained in an amount of 0.01 to 15 parts by weight with respect to 100 parts by weight of the acrylic polymer. More preferably, 10 parts by weight is contained. When the content is less than 0.01 part by weight, the crosslinking formation by the crosslinking agent is insufficient, the cohesive force of the pressure-sensitive adhesive composition is reduced, and sufficient heat resistance may not be obtained. There is a tendency to cause the rest. On the other hand, when the content exceeds 15 parts by weight, the cohesive force of the polymer is large, the fluidity is lowered, the wettability to the adherend is insufficient, and it tends to cause peeling.

Further, it can be added as a polyfunctional monomer having two or more radiation-reactive unsaturated bonds as a substantial cross-linking agent, and cross-linked by radiation or the like. Polyfunctional monomers having two or more radiation-reactive unsaturated bonds include one or more types of radiation that can be crosslinked (cured) by irradiation with radiation such as vinyl, acryloyl, methacryloyl, and vinylbenzyl groups. A polyfunctional monomer component having two or more reactivity is used. In general, those having 10 or less radiation-reactive unsaturated bonds are preferably used. A polyfunctional monomer may be used independently and may be used in mixture of 2 or more types.

Specific examples of the polyfunctional monomer include, for example, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, and 1,6-hexane. Examples thereof include diol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, divinylbenzene, N, N′-methylenebisacrylamide and the like.

The amount of the polyfunctional monomer used is appropriately selected depending on the balance with the acrylic polymer to be crosslinked and further depending on the intended use as an adhesive sheet. In general, in order to obtain sufficient heat resistance by the cohesive force of the acrylic pressure-sensitive adhesive, it is preferably blended at 0.1 to 30 parts by weight with respect to 100 parts by weight of the (meth) acrylic polymer. Moreover, it is more preferable to mix | blend at 10 weight part or less with respect to 100 weight part of (meth) acrylic-type polymers from the point of a softness | flexibility and adhesiveness.

Examples of the radiation include ultraviolet rays, laser rays, α rays, β rays, γ rays, X rays, electron rays, and the like, and ultraviolet rays are preferably used from the viewpoints of controllability, good 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. In addition, when using an ultraviolet-ray as a radiation, a photoinitiator is added to an acrylic adhesive.

The photopolymerization initiator may be any substance that generates radicals or cations by irradiating ultraviolet rays having an appropriate wavelength that can trigger the polymerization reaction according to the type of the radiation-reactive component.

Examples of the radical photopolymerization initiator include benzoin, benzoin methyl ether, benzoin ethyl ether, o-benzoylbenzoic acid methyl-p-benzoin ethyl ether, benzoin isopropyl ether, benzoins such as α-methylbenzoin, benzyldimethyl ketal, Acetophenones such as trichloroacetophenone, 2,2-diethoxyacetophenone, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methylpropiophenone, 2-hydroxy-4'-isopropyl-2-methylpropiophenone, etc. Benzophenones such as propiophenones, benzophenone, methylbenzophenone, p-chlorobenzophenone, p-dimethylaminobenzophenone, 2-chlorothioxanthone, 2-ethyl Thioxanthones such as oxanthone and 2-isopropylthioxanthone, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, (2,4,6-trimethylbenzoyl)- Examples include acylphosphine oxides such as (ethoxy) -phenylphosphine oxide, benzyl, dibenzosuberone, and α-acyloxime ester.

Examples of the cationic photopolymerization initiator include onium salts such as aromatic diazonium salts, aromatic iodonium salts, and aromatic sulfonium salts, organometallic complexes such as iron-allene complexes, titanocene complexes, and arylsilanol-aluminum complexes, nitro Examples thereof include benzyl ester, sulfonic acid derivative, phosphoric acid ester, phenol sulfonic acid ester, diazonaphthoquinone, and N-hydroxyimide sulfonate. The photopolymerization initiators may be used alone or in combination of two or more.

The photopolymerization initiator is preferably blended in an amount of usually 0.1 to 10 parts by weight, preferably 0.2 to 7 parts by weight with respect to 100 parts by weight of the (meth) acrylic polymer.

It is also possible to use a photoinitiated polymerization aid such as amines in combination. Examples of the photoinitiator include 2-dimethylaminoethyl benzoate, dimethylaminoacetophenone, p-dimethylaminobenzoic acid ethyl ester, p-dimethylaminobenzoic acid isoamyl ester, and the like. The above photopolymerization initiation assistants may be used alone or in admixture of two or more. The polymerization initiation assistant is preferably blended in an amount of 0.05 to 10 parts by weight, more preferably 0.1 to 7 parts by weight, with respect to 100 parts by weight of the acrylic polymer.

Furthermore, the pressure-sensitive adhesive composition used in the pressure-sensitive adhesive sheet of the present invention includes various conventionally known tackifiers, surface lubricants, leveling agents, antioxidants, corrosion inhibitors, light stabilizers, ultraviolet absorbers, and polymerization inhibition. Add appropriate additives according to the use of various conventionally known additives such as agents, silane coupling agents, inorganic or organic fillers, powders such as metal powders and pigments, particles, foils, etc. Can do.

On the other hand, the pressure-sensitive adhesive layer of the present invention is obtained by crosslinking the pressure-sensitive adhesive composition as described above. Moreover, the pressure-sensitive adhesive sheets of the present invention are formed by forming such a pressure-sensitive adhesive layer on a support (support film). At that time, the pressure-sensitive adhesive composition is generally crosslinked after application of the pressure-sensitive adhesive composition, but the pressure-sensitive adhesive layer comprising the crosslinked pressure-sensitive adhesive composition can be transferred to a support film or the like. is there.

In the case where a photopolymerization initiator as an optional component is added as described above, the pressure-sensitive adhesive composition is applied directly on the object to be protected, or applied to one side or both sides of the support (support film). Then, the pressure-sensitive adhesive layer can be obtained by light irradiation. 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 method for forming the pressure-sensitive adhesive layer on the film is not particularly limited. For example, the pressure-sensitive adhesive composition is coated on a support (support film), and the polymerization solvent is removed by drying to form the pressure-sensitive adhesive layer on the support film. It is produced by forming. Thereafter, curing may be performed for the purpose of adjusting the component transfer of the pressure-sensitive adhesive layer or adjusting the crosslinking reaction. In addition, when the pressure-sensitive adhesive composition is coated on a support film to produce pressure-sensitive adhesive sheets, one or more solvents other than the polymerization solvent are newly added to the composition so that the pressure-sensitive adhesive composition can be uniformly coated on the support film. You may add to.

Moreover, as a formation method of the adhesive layer of this invention, the well-known method used for manufacture of adhesive sheets is used. Specific examples include roll coating, gravure coating, reverse coating, roll brushing, spray coating, air knife coating, extrusion coating using a die coater, and the like.

The pressure-sensitive adhesive sheets of the present invention have various pressure-sensitive adhesive layers made of a plastic film such as a polyester film or a porous material such as paper or nonwoven fabric so that the thickness of the pressure-sensitive adhesive layer is usually about 3 to 100 μm, preferably about 5 to 50 μm. It is applied and formed on one side or both sides of the support to form a sheet or tape. In particular, in the case of a surface protective film, it is preferable to use a plastic substrate as a support (support film).

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, poly Polyester film such as butylene terephthalate, polyacrylate film, polystyrene film, nylon 6, nylon 6,6, polyamide film such as partially aromatic polyamide, polyvinyl chloride film, polyvinylidene chloride film, polycarbonate Such as ball titanate film, and the like. The thickness of the film is usually about 5 to 200 μm, preferably about 10 to 100 μm.

For plastic substrates, if necessary, silicone-based, fluorine-based, long-chain alkyl-based or fatty acid amide-based mold release agents, mold release with silica powder, etc., acid treatment, acid treatment, alkali treatment, primer treatment, Anti-adhesive treatment such as corona treatment, plasma treatment and ultraviolet treatment, coating type, kneading type, vapor deposition type and the like can also be carried out.

The plastic substrate used for the surface protective film of the present invention is more preferably subjected to antistatic treatment. The antistatic treatment applied to the plastic substrate is not particularly limited. For example, a method of providing an antistatic layer on at least one surface of a generally used film or a method of kneading a kneading type antistatic agent into a plastic film. Used. As a method of providing an antistatic layer on at least one surface of the film, an antistatic resin comprising an antistatic agent and a resin component, a conductive polymer, a method of applying a conductive resin containing a conductive material, or a conductive material is deposited. Or the method of plating is mention | raise | lifted.

Examples of the antistatic agent contained in the antistatic resin include cationic antistatic agents having cationic functional groups such as quaternary ammonium salts, pyridinium salts, primary, secondary and tertiary amino groups, and sulfones. Anionic antistatic agents with anionic functional groups such as acid salts, sulfate esters, phosphonates, phosphate esters, alkylbetaines and derivatives thereof, imidazolines and derivatives thereof, and amphoteric antistatic agents such as alanine and derivatives thereof Nonionic antistatic agents such as agents, amino alcohols and derivatives thereof, glycerin and derivatives thereof, polyethylene glycol and derivatives thereof, and monomers having ion conductive groups of the above cation type, anion type and zwitterionic type Examples thereof include ionic conductive polymers obtained by polymerization or copolymerization. These compounds may be used alone or in combination of two or more.

Specifically, as a cation type antistatic agent, for example, quaternary ammonium group such as alkyltrimethylammonium salt, acyloylamidopropyltrimethylammonium methosulfate, alkylbenzylmethylammonium salt, acylcholine chloride, polydimethylaminoethyl methacrylate, etc. (Meth) acrylate copolymers having quaternary, styrene copolymers having quaternary ammonium groups such as polyvinylbenzyltrimethylammonium chloride, diallylamine copolymers having quaternary ammonium groups such as polydiallyldimethylammonium chloride, and the like. These compounds may be used alone or in combination of two or more.

Examples of the anionic antistatic agent include alkyl sulfonate, alkyl benzene sulfonate, alkyl sulfate ester salt, alkyl ethoxy sulfate ester salt, alkyl phosphate ester salt, and sulfonic acid group-containing styrene copolymer. These compounds may be used alone or in combination of two or more.

Examples of zwitterionic antistatic agents include alkylbetaines, alkylimidazolium betaines, and carbobetaine graft copolymers. These compounds may be used alone or in combination of two or more.

Nonionic antistatic agents include, for example, fatty acid alkylolamide, di (2-hydroxyethyl) alkylamine, polyoxyethylene alkylamine, fatty acid glycerin ester, polyoxyethylene glycol fatty acid ester, sorbitan fatty acid ester, polyoxysorbitan fatty acid Examples thereof include esters, polyoxyethylene alkyl phenyl ethers, polyoxyethylene alkyl ethers, polyethylene glycols, polyoxyethylene diamines, copolymers composed of polyethers, polyesters and polyamides, and methoxypolyethylene glycol (meth) acrylates. These compounds may be used alone or in combination of two or more.

Examples of the conductive polymer include polyaniline, polypyrrole, polythiophene and the like. These conductive polymers may be used alone or in combination of two or more.

Examples of the conductive material include tin oxide, antimony oxide, indium oxide, cadmium oxide, titanium oxide, zinc oxide, indium, tin, antimony, gold, silver, copper, aluminum, nickel, chromium, titanium, iron, cobalt, Examples include copper iodide, and alloys or mixtures thereof. These conductive materials may be used alone or in combination of two or more.

As the resin component used for the antistatic resin and the conductive resin, for example, general-purpose resins such as polyester, acrylic, polyvinyl, urethane, melamine, and epoxy are used. In the case of a polymer type antistatic agent, it is not necessary to contain a resin component. Further, the antistatic resin component may contain a methylol- or alkylol-containing melamine-based, urea-based, glyoxal-based, acrylamide-based compound, epoxy compound, or isocyanate compound as a crosslinking agent.

The antistatic layer can be formed by, for example, diluting the antistatic resin, conductive polymer, or conductive resin with a solvent such as an organic solvent or water, and applying and drying the coating liquid on a plastic film. Is done.

Examples of the organic solvent used for forming the antistatic layer include methyl ethyl ketone, acetone, ethyl acetate, tetrahydrofuran, dioxane, cyclohexanone, n-hexane, toluene, xylene, methanol, ethanol, n-propanol, and isopropanol. can give. These solvents may be used alone or in combination of two or more.

As a coating method in forming the antistatic layer, a known coating method is appropriately used. Specifically, for example, roll coating, gravure coating, reverse coating, roll brush, spray coating, air knife coating, impregnation and curtain coating are used. The law is raised.

The thickness of the antistatic resin layer, the conductive polymer, and the conductive resin is usually about 0.01 to 5 μm, preferably about 0.03 to 1 μm.

Examples of the method for depositing or plating the conductive material include vacuum deposition, sputtering, ion plating, chemical vapor deposition, spray pyrolysis, chemical plating, and electroplating.

The thickness of the conductive material layer is usually 20 to 10,000 mm, preferably 50 to 5000 mm.

As the kneading type antistatic agent, the above antistatic agent is appropriately used. The amount of the kneading type antistatic agent is 20% by weight or less, preferably 0.05 to 10% by weight, based on the total weight of the plastic film. The kneading method is not particularly limited as long as the antistatic agent can be uniformly mixed with the resin used for the plastic film. For example, a heating roll, a Banbury mixer, a pressure kneader, a biaxial kneader or the like is used. It is done.

For plastic films, silicone, fluorine, long-chain alkyl or fatty acid amide release agents, release with silica powder, antifouling treatment, acid treatment, alkali treatment, primer treatment, corona Easy adhesion treatment such as treatment, plasma treatment, and ultraviolet treatment can also be performed.

In the pressure-sensitive adhesive sheets of the present invention, a separator can be bonded to the pressure-sensitive adhesive surface for the purpose of protecting the pressure-sensitive adhesive surface as necessary. As a base material constituting the separator, there are paper and plastic film, but a plastic film is preferably used from the viewpoint of excellent surface smoothness.

The film is not particularly limited as long as it can protect the pressure-sensitive adhesive layer. For example, polyethylene, polypropylene, poly-1-butene, poly-4-methyl-1-pentene, ethylene / propylene copolymer Polyolefin films such as ethylene / 1-butene copolymer, ethylene / vinyl acetate copolymer, ethylene / ethyl acrylate copolymer, ethylene / vinyl alcohol copolymer, polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, etc. Polyester film, polyacrylate film, polystyrene film, nylon 6, nylon 6,6, polyamide film such as partially aromatic polyamide, polyvinyl chloride film, polyvinylidene chloride film, polycarbonate film Etc., and the like.

The thickness of the film is usually about 5 to 200 μm, preferably about 10 to 100 μm. The adhesive layer bonding surface of the film is appropriately treated with a release agent such as a silicone, fluorine, long chain alkyl or fatty acid amide release agent, silica powder or the like.

The pressure-sensitive adhesive composition and the pressure-sensitive adhesive sheet using the present invention are used particularly for plastic products and the like that are likely to generate static electricity, and in particular, polarizing plates, wave plates, optical compensation films, light used for liquid crystal displays and the like. It can be used as a surface protective film used for the purpose of protecting the surface of an optical member such as a diffusion sheet or a reflection sheet.

Examples and the like specifically showing the configuration and effects of the present invention will be described below. In addition, the evaluation item in an Example etc. measured as follows.

<Measurement of acid value>
The acid value was measured using an automatic titration device (COM-550, manufactured by Hiranuma Sangyo Co., Ltd.) and obtained from the following formula.
A = {(Y−X) × f × 5.611} / M
A: Acid number Y: Titration volume of sample solution (ml)
X: Titration volume of a solution containing only 50 g of mixed solvent (ml)
f; Factor M of the titration solution; Weight of polymer sample (g)

The measurement conditions are as follows.
Sample solution: About 0.5 g of a polymer sample was dissolved in 50 g of a mixed solvent (toluene / 2-propanol / distilled water = 50 / 49.5 / 0.5, weight ratio) to obtain a sample solution.
Titration solution: 0.1N, 2-propanol potassium hydroxide solution (manufactured by Wako Pure Chemical Industries, Ltd., for petroleum product neutralization value test)
Electrode: Glass electrode; GE-101, Comparative electrode; RE-201
Measurement mode: Petroleum product neutralization number test 1

<Measurement of molecular weight>
The molecular weight was measured by using a GPC apparatus (HLC-8220 GPC, manufactured by Tosoh Corporation), and obtained in terms of polystyrene. The measurement conditions are as follows. Sample concentration: 0.2% by weight (THF solution)
Sample injection volume: 10 μl
Eluent: THF
Flow rate: 0.6 ml / min
Measurement temperature: 40 ° C
column:
Sample column: TSKguardcolumn SuperHZ-H (1) + TSKgel SuperHZM-H (2)
Reference column; TSKgel SuperH-RC (1)
Detector: Differential refractometer

<Measurement of glass transition temperature>
The glass transition temperature Tg (° C.) was determined by the following formula using the following literature values as the glass transition temperature Tgn (° C.) of the homopolymer of each monomer.

Formula: 1 / (Tg + 273) = Σ [Wn / (Tgn + 273)]
[Wherein, Tg (° C.) is the glass transition temperature of the copolymer, Wn (−) is the weight fraction of each monomer, Tgn (° C.) is the glass transition temperature of the homopolymer of each monomer, and n is the type of each monomer Represents. ]
2-ethylhexyl acrylate: -70 ° C
2-hydroxyethyl acrylate: -15 ° C

<NMR measurement>
NMR measurement was performed under the following measurement conditions using a nuclear magnetic resonance apparatus (EX-400, manufactured by JEOL Ltd.).
Observation frequency: 400 MHz ( ¹ H), 100 MHz ( ¹³ C)
Measuring solvent: actone-d ₆
Measurement temperature: 23 ° C

<XRF measurement>
XRF measurement was performed under the following measurement conditions using a scanning X-ray fluorescence analyzer (manufactured by Rigaku Corporation, ZSX-100e).
Measuring method: filter paper method X-ray source: Rh

<FT-IR measurement>
The FT-IR measurement was performed under the following measurement conditions using an infrared spectrophotometer (manufactured by Nicolet, Magna-560).
Measuring method: ATR method Detector: DTGS
Resolution: 4.0 cm ⁻¹
Integration count: 64 times

<Preparation of acrylic polymer>
(Acrylic polymer (A))
In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas introduction tube, and a condenser, 200 parts by weight of 2-ethylhexyl acrylate, 8 parts by weight of 2-hydroxyethyl acrylate, 2,2′-azobis as a polymerization initiator Charge 0.4 parts by weight of isobutyronitrile and 312 parts by weight of ethyl acetate, introduce nitrogen gas while gently stirring, and perform a polymerization reaction for 5 hours while maintaining the liquid temperature in the flask at around 60 ° C. A solution (40% by weight) of polymer (A) was prepared. This acrylic polymer (A) had Tg = −68 ° C., a weight average molecular weight of 550,000, and an acid value of 0.0.

<Preparation of ionic liquid>
(Ionic liquid (1))
A solution obtained by diluting 10 parts by weight of 1-butyl-3-methylpyridinium chloride (manufactured by Wako Pure Chemical Industries, Ltd.) to 20% by weight with distilled water is added to a four-necked flask equipped with a stirring blade, a thermometer, and a condenser. Then, a solution obtained by diluting 19 parts by weight of lithium bis (trifluoromethanesulfonyl) imide (manufactured by Kishida Chemical Co., Ltd.) to 20% by weight with distilled water was gradually added while rotating the stirring blade. After the addition, stirring was continued at 25 ° C. for 2 hours, and then allowed to stand for 12 hours, and the supernatant was removed to obtain a liquid product. The obtained liquid product was washed with 200 parts by weight of distilled water three times and dried in an environment of 110 ° C. for 2 hours to obtain 20 parts by weight of a liquid ionic liquid (1) at 25 ° C.

The obtained ionic liquid (1) was subjected to NMR ( ¹ H, ¹³ C) measurement, FT-IR measurement, and XRF measurement, and identified as 1-butyl-3-methylpyridinium bis (trifluoromethanesulfonyl) imide. ,confirmed.

<Preparation of antistatic agent solution>
(Antistatic agent solution (a))
In a four-necked flask equipped with a stirring blade, thermometer, and condenser, 6 parts by weight of ionic liquid (1), 0.2 parts by weight of lithium iodide, nonionic reactive surfactant (manufactured by Asahi Denka Kogyo Co., Ltd.) , ADEKA rear soap ER-10) 3.8 parts by weight and 90 parts by weight of ethyl acetate, and the mixture was stirred for 2 hours while maintaining the liquid temperature in the flask at around 80 ° C. to obtain an antistatic agent solution (a) (10 % By weight) was prepared.

(Antistatic agent solution (b))
In a four-necked flask equipped with a stirring blade, thermometer, and condenser, 4 parts by weight of ionic liquid (1), 0.5 parts by weight of lithium iodide, nonionic reactive surfactant (manufactured by Asahi Denka Kogyo Co., Ltd.) , ADEKA rear soap ER-10) 9.5 parts by weight and ethyl acetate 126 parts by weight, the liquid temperature in the flask was kept at around 80 ° C. and mixed and stirred for 2 hours to obtain an antistatic agent solution (b) (10 % By weight) was prepared.

(Antistatic agent solution (c))
In a four-necked flask equipped with a stirring blade, a thermometer, and a condenser, 6 parts by weight of ionic liquid (1), 0.2 part by weight of Li (CF ₃ SO ₂ ) ₂ N, a nonionic reactive surfactant ( Asahi Denka Kogyo Co., Ltd., ADEKA rear soap ER-10) 3.8 parts by weight and ethyl acetate 90 parts by weight were charged, and the mixture was stirred and stirred for 2 hours while keeping the liquid temperature in the flask at around 80 ° C. (C) (10% by weight) was prepared.

(Antistatic agent solution (d))
A four-necked flask equipped with a stirring blade, thermometer and cooler was charged with 10 parts by weight of lithium iodide and 90 parts by weight of ethyl acetate, and the mixture was stirred for 2 hours while maintaining the liquid temperature in the vicinity of 80 ° C. An antistatic agent solution (d) (10% by weight) was prepared.

(Antistatic agent solution (e))
In a four-necked flask equipped with a stirring blade, a thermometer, and a condenser, 0.1 part by weight of lithium iodide, 9.9 parts by weight of polypropylene glycol (number average molecular weight: 2000, diol type), and 90 parts by weight of ethyl acetate were added. The mixture was stirred and mixed and stirred for 2 hours while maintaining the liquid temperature in the flask at around 80 ° C. to prepare an antistatic agent solution (e) (10% by weight).

(Antistatic agent solution (f))
In a four-necked flask equipped with a stirring blade, a thermometer and a condenser, 5 parts by weight of ionic liquid (1), nonionic reactive surfactant (Adeka Soap ER-10, manufactured by Asahi Denka Kogyo Co., Ltd.) 5 An antistatic agent solution (f) (10 wt%) was prepared by charging 30 parts by weight of ethyl acetate and 90 parts by weight of ethyl acetate, and mixing and stirring for 30 minutes while keeping the liquid temperature in the flask at about room temperature (25 ° C.).

<Preparation of antistatic treatment film>
Antistatic by diluting 10 parts by weight of an antistatic agent (manufactured by Solvex, Microsolver RMd-142, mainly composed of tin oxide and polyester resin) with a mixed solvent consisting of 30 parts by weight of water and 70 parts by weight of methanol An agent solution was prepared. The obtained antistatic agent solution was applied onto a polyethylene terephthalate (PET) film (thickness: 38 μm) using a Meyer bar and dried at 130 ° C. for 1 minute to remove the solvent and remove the antistatic layer (thickness). Thickness: 0.2 μm) to form an antistatic film.

[Example 1]
(Preparation of adhesive composition)
A solution (40% by weight) of the acrylic polymer (A) is diluted to 20% by weight with ethyl acetate, 1 part by weight of the antistatic agent solution (a) (10% by weight) is added to 100 parts by weight of this solution, and a crosslinking agent. As an isocyanurate form of hexamethylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., Coronate HX) and 0.4 part by weight of dibutyltin dilaurate (1% by weight ethyl acetate solution) as a crosslinking catalyst, The acrylic pressure-sensitive adhesive solution (1) was prepared by mixing and stirring for about 1 minute.

(Preparation of adhesive sheet)
The said acrylic adhesive solution (1) was apply | coated to the surface opposite to the antistatic process surface of said antistatic process film, and it heated at 110 degreeC for 3 minute (s), and formed the 20-micrometer-thick adhesive layer. Next, a silicone-treated surface of a polyethylene terephthalate film having a thickness of 25 μm having one surface subjected to silicone treatment was bonded to the surface of the pressure-sensitive adhesive layer to produce a pressure-sensitive adhesive sheet.

[Example 2]
(Preparation of adhesive composition)
The acrylic polymer (A) solution (40% by weight) was diluted to 20% by weight with ethyl acetate, and 100 parts by weight of this solution was added with 1.4 parts by weight of the antistatic agent solution (b) (10% by weight), Add 0.35 part by weight of isocyanurate of hexamethylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., Coronate HX) as a crosslinking agent, and add 0.4 part by weight of dibutyltin dilaurate (1% by weight ethyl acetate solution) as a crosslinking catalyst. An acrylic pressure-sensitive adhesive solution (2) was prepared by mixing and stirring for about 1 minute at (25 ° C.).

(Preparation of adhesive sheet)
A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that the acrylic pressure-sensitive adhesive solution (2) was used instead of the acrylic pressure-sensitive adhesive solution (1).

Example 3
(Preparation of adhesive composition)
A solution (40% by weight) of the acrylic polymer (A) is diluted to 20% by weight with ethyl acetate, and 1 part by weight of the antistatic agent solution (c) (10% by weight) is added to 100 parts by weight of the solution. As an isocyanurate of hexamethylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., Coronate HX) and 0.4 parts by weight of dibutyltin dilaurate (1% by weight ethyl acetate solution) as a crosslinking catalyst. The acrylic pressure-sensitive adhesive solution (3) was prepared by mixing and stirring for about 1 minute.

(Preparation of adhesive sheet)
A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that the acrylic pressure-sensitive adhesive solution (3) was used instead of the acrylic pressure-sensitive adhesive solution (1).

[Comparative Example 1]
(Preparation of adhesive composition)
The acrylic polymer (A) solution (40% by weight) was diluted to 20% by weight with ethyl acetate, and 100 parts by weight of this solution was added with 1.4 parts by weight of the antistatic agent solution (d) (10% by weight). Add 0.5 parts by weight of isocyanurate of hexamethylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd., Coronate HX) as a crosslinking agent and 0.4 parts by weight of dibutyltin dilaurate (1% by weight ethyl acetate solution) as a crosslinking catalyst. An acrylic pressure-sensitive adhesive solution (4) was prepared by mixing and stirring for about 1 minute under (25 ° C.).

(Preparation of adhesive sheet)
A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that the acrylic pressure-sensitive adhesive solution (4) was used instead of the acrylic pressure-sensitive adhesive solution (1).

[Comparative Example 2]
(Preparation of adhesive composition)
An acrylic pressure-sensitive adhesive solution was used in the same manner as in Example 1 except that 20 parts by weight of the antistatic agent solution (e) (10% by weight) was used instead of 1 part by weight of the antistatic agent (a) solution. (5) was prepared.

(Preparation of adhesive sheet)
A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 except that the acrylic pressure-sensitive adhesive solution (5) was used instead of the acrylic pressure-sensitive adhesive solution (1).

[Comparative Example 3]
(Preparation of adhesive composition)
A solution (40% by weight) of the acrylic polymer (A) is diluted to 20% by weight with ethyl acetate, and 2.0 parts by weight of the ionic liquid (1) is added to 100 parts by weight of this solution, and hexamethylene diisocyanate as a crosslinking agent. Isocyanurate body (manufactured by Nippon Polyurethane Industry Co., Ltd., Coronate HX) 0.8 parts by weight, dibutyltin dilaurate (1% by weight ethyl acetate solution) 0.4 parts by weight as a crosslinking catalyst, and at room temperature (25 ° C.) An acrylic pressure-sensitive adhesive solution (6) was prepared by mixing and stirring for about 1 minute.

(Preparation of adhesive sheet)
A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that the acrylic pressure-sensitive adhesive solution (6) was used instead of the acrylic pressure-sensitive adhesive solution (1).

[Comparative Example 4]
(Preparation of adhesive composition)
An acrylic pressure-sensitive adhesive similar to Example 1, except that 1.2 parts by weight of the antistatic agent solution (f) (10% by weight) was used instead of 1 part by weight of the antistatic agent solution (a). Solution (7) was prepared.

(Preparation of adhesive sheet)
A pressure-sensitive adhesive sheet was prepared in the same manner as in Example 1 except that the acrylic pressure-sensitive adhesive solution (7) was used instead of the acrylic pressure-sensitive adhesive solution (1).

[Comparative Example 5]
(Preparation of adhesive composition)
A solution (40% by weight) of the acrylic polymer (A) was diluted to 20% by weight with ethyl acetate, and 100 parts by weight of this solution was mixed with lauryltrimethylammonium chloride (Kao Co., Cotamin 24P) as the cationic surfactant. ) 2.0 parts by weight, 1 part by weight of trimethylolpropane / tolylene diisocyanate trimer adduct (manufactured by Nippon Polyurethane Industry Co., Ltd., Coronate L, 75% by weight ethyl acetate solution) as a crosslinking agent, dibutyltin dilaurate (as a crosslinking catalyst) A 1 wt% ethyl acetate solution) (0.6 parts by weight) was added, and the mixture was stirred at room temperature (25 ° C) for about 1 minute to prepare an acrylic pressure-sensitive adhesive solution (8).

(Preparation of adhesive sheet)
A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that the acrylic pressure-sensitive adhesive solution (8) was used instead of the acrylic pressure-sensitive adhesive solution (1).

[Comparative Example 6]
(Preparation of adhesive composition)
An acrylic pressure-sensitive adhesive solution (9) was prepared in the same manner as in Example 1 except that the antistatic agent (a) was not used.

(Preparation of adhesive sheet)
A pressure-sensitive adhesive sheet was produced in the same manner as in Example 1 except that the acrylic pressure-sensitive adhesive solution (9) was used instead of the acrylic pressure-sensitive adhesive solution (1).

About the adhesive sheet obtained by said Example, comparative example, etc., the stripping voltage, corrosivity, and contamination | pollution property were evaluated in the following ways.

<Measurement of peeling voltage>
The pressure-sensitive adhesive sheet was cut to a size of 70 mm in width and 130 mm in length, the separator was peeled off, and then the acrylic plate (Mitsubishi Rayon Co., Acrylite, thickness: 1 mm, width: 70 mm, length: 100 mm, which had been previously neutralized. ) Was bonded to the surface of the polarizing plate (manufactured by Nitto Denko Corporation, SEG1425WVAGS2B, width: 70 mm, length: 100 mm) with a hand roller so that one end protruded 30 mm.

After being left for one day in an environment of 23 ° C. × 50% RH, the sample was set at a predetermined position as shown in FIG. One end protruding 30 mm was fixed to an automatic winder, and peeled so that the peeling angle was 150 ° and the peeling speed was 10 m / min. The potential of the polarizing plate surface generated at this time was measured with a potential measuring machine (KSD-0103, manufactured by Kasuga Denki Co., Ltd.) fixed at the center position in the sample length direction. The measurement was performed in an environment of 23 ° C. × 50% RH.

<Corrosive evaluation>
The pressure-sensitive adhesive sheet is cut into a size of 30 mm in width and 80 mm in length, the separator is peeled off, and then crimped with a hand roller onto an aluminum foil (Nippon Foil Co., Ltd., Nippaku foil, width: 50 mm, length: 100 mm) for evaluation. A sample was made.

The evaluation sample was allowed to stand in an environment of 60 ° C. × 90% RH for 24 hours and in an environment of 23 ° C. × 50% RH for 2 hours, and then the pressure-sensitive adhesive sheet was peeled off from the aluminum foil by hand. The corrosion state of was visually observed. The evaluation criteria are as follows.
When discoloration is not recognized: ○
If discoloration is observed: ×

<Evaluation of contamination>
After the adhesive sheet is cut into a size of 50 mm in width and 80 mm in length and the separator is peeled off, it is pressure-bonded to a polarizing plate (manufactured by Nitto Denko Corporation, SEG1425DU, width: 70 mm, length: 100 mm) with a hand roller, and an evaluation sample Was made.

The evaluation sample was left in an environment of 25 ° C. × 50% RH for 72 hours, and then the pressure-sensitive adhesive sheet was peeled from the adherend by hand, and the contamination state of the adherend surface at that time was visually observed. The evaluation criteria are as follows.
If no contamination was found: ○
If contamination is found: ×

The results are shown in Table 1.

As is clear from the results of Table 1 above, when the pressure-sensitive adhesive composition prepared according to the present invention was used (Examples 1 to 3), in any of the examples, the absolute value of the stripping voltage to the polarizing plate It was clarified that the value was suppressed to a low value of 0.5 kV or less, and there was no occurrence of corrosion on the metal or contamination of the polarizing plate.

On the other hand, when 0.1 parts by weight or more of the alkali metal salt was used as the antistatic agent (Comparative Examples 1 and 2), the peeling band voltage of the polarizing plate was suppressed to a low value, but corrosion to metal Occurrence was observed. On the other hand, when only 10 parts by weight of the ionic liquid was used as the antistatic agent (Comparative Example 3), the peeling band voltage of the polarizing plate was suppressed to a low value, and no occurrence of corrosion on the metal was observed. Occurrence of contamination on the board was observed. Further, in the case of using an ionic liquid and a surfactant without using an alkali metal salt as an antistatic agent (Comparative Example 4), in the case of using no antistatic agent (Comparative Example 6), in either case, Although no corrosion on the metal and no contamination of the polarizing plate were observed, the result was that the stripping voltage of the polarizing plate was high. Furthermore, when only the surfactant was used as the antistatic agent (Comparative Example 5), the peeling band voltage of the polarizing plate was suppressed to a low value, but corrosion of the metal and contamination of the polarizing plate were observed. It was. Therefore, in any of the pressure-sensitive adhesive sheets of Comparative Examples 1 to 6, it is impossible to side by side suppress the stripping voltage to the polarizing plate, suppress the corrosion to the metal, and suppress the contamination to the adherend. It was revealed that the composition is not suitable for an adhesive composition for an antistatic adhesive sheet.

Therefore, the pressure-sensitive adhesive composition of the present invention is a pressure-sensitive adhesive composition that is excellent in antistatic properties of the adherend when peeled and has reduced corrosion to metals and contamination to the adherend. I was able to confirm.

Claims (11)

Ionic liquids (excluding surfactants having ethylene oxide groups), alkali metal salts, isocyanate compounds as crosslinking agents, and polymers having a glass transition temperature Tg of 0 ° C. or less as base polymers (excluding surfactants having ethylene oxide groups) A pressure-sensitive adhesive composition comprising
The polymer having a glass transition temperature Tg of 0 ° C. or lower is an acrylic polymer,
The ionic liquid is at least one of a nitrogen-containing onium salt, a sulfur-containing onium salt, or a phosphorus-containing onium salt,
The pressure-sensitive adhesive composition comprising 0.005 part by weight or more and less than 0.1 part by weight of the alkali metal salt with respect to 100 parts by weight of the base polymer.   The pressure-sensitive adhesive composition according to claim 1, wherein the pressure-sensitive adhesive composition further contains a surfactant. Wherein the ionic liquid, the pressure-sensitive adhesive composition according to any one of claims 1-2 which contains one or more kinds of cations represented by the following general formula (A) ~ (D).

[R _a in the formula (A) represents a hydrocarbon group having 4 to 20 carbon atoms and may include a hetero atom, and R _b and R _c may be the same or different, and may be hydrogen or _C 1 to _C 16. Represents a hydrocarbon group and may contain heteroatoms. However, when the nitrogen atom contains a double bond, there is no R _c . ]
[R _d in the formula (B) represents a hydrocarbon group having 2 to 20 carbon atoms and may contain a hetero atom, and R _e , R _f , and R _g are the same or different and represent hydrogen or carbon number. Represents 1 to 16 hydrocarbon groups and may contain heteroatoms. ]
[R _h in the formula (C) represents a hydrocarbon group having 2 to 20 carbon atoms, and may contain a hetero atom, and R _i , R _j , and R _k may be the same or different and represent hydrogen or carbon number. Represents 1 to 16 hydrocarbon groups and may contain heteroatoms. ]
[Z in Formula (D) represents a nitrogen, sulfur, or phosphorus atom, and R ₁ , R _m , R _n , and R _o are the same or different and represent a hydrocarbon group having 1 to 20 carbon atoms. And may contain heteroatoms. However, when Z is a sulfur atom, there is no _Ro . ] The pressure-sensitive adhesive composition according to any one of claims 1 to 3 , wherein the alkali metal salt is a lithium salt. The surfactant, pressure-sensitive adhesive composition according to any one of claims 2-4 is a surfactant having an ethylene oxide group. Glass transition temperature Tg is 0 ℃ following polymers, claim 1-5 is an acrylic polymer mainly composed of one or more acrylate and / or methacrylate having an alkyl group of 1 to 14 carbon atoms 2. The pressure-sensitive adhesive composition according to 1. When the acid value of the acrylic polymer is 29 or less, the pressure-sensitive adhesive composition according to any one of claims 1-6. Pressure-sensitive adhesive layer obtained by crosslinking a pressure-sensitive adhesive composition according to any one of claims 1-7. Pressure-sensitive adhesive sheet, wherein by crosslinking the pressure-sensitive adhesive layer a pressure-sensitive adhesive composition, that obtained by forming on one or both sides of the support according to any one of claims 1-7. A pressure-sensitive adhesive layer formed by crosslinking the pressure-sensitive adhesive composition according to any one of claims 1 to 7 is formed on one side or both sides on a support made of a plastic substrate subjected to antistatic treatment. Characteristic surface protective film. The optical member formed by bonding the surface protection film of Claim 10 .

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