ACRYLIC PRESSURE-SENSITIVE ADHESIVE SHEET
The present invention relates to an acrylic pressure-sensitive adhesive sheet including: a viscoelastic material layer (X) containing hollow microspheres; and a pressure-sensitive adhesive layer (Y) provided on at least one face of the viscoelastic material layer (X) and formed from a monomer composition, in which the monomer composition includes the following monomers (m1), (m2) and (m3) as essential monomer components, in which a content of the monomer (m1) is 50 to 85% by weight, a content of the monomer (m2) is 0.1 to 20% by weight, and a content of the monomer (m3) is 2 to 40% by weight, based on a total amount of monomer components constituting the monomer composition, (m1) an alkyl(meth)acrylate monomer including an alkyl group having 1 to 20 carbon atoms, which is represented by the following formula (1), [Chem. 1] CH 2 ═C(R 1 )COOR 2 (1) in which R 1 represents a hydrogen atom or a methyl group, and R 2 represents an alkyl group having 1 to 20 carbon atoms, (m2) an N-hydroxyalkyl(meth)acrylamide monomer having a hydroxyalkyl group having 1 to 4 carbon atoms, which is represented by the following formula (2), [Chem. 2] CH 2 ═C(R 3 )CONHR 4 (2) in which R 3 represents a hydrogen atom or a methyl group, and R 4 represents a hydroxyalkyl group having 1 to 4 carbon atoms, (m3) a vinyl monomer having a nitrogen atom in a backbone thereof, except for the monomer (m2).
1 . An acrylic pressure-sensitive adhesive sheet comprising:
a viscoelastic material layer (X) containing hollow microspheres; and
a pressure-sensitive adhesive layer (Y) provided on at least one face of the viscoelastic material layer (X) and formed from a monomer composition,
wherein said monomer composition includes the following monomers (m1), (m2) and (m3) as essential monomer components, in which a content of the monomer (m1) is 50 to 85% by weight, a content of the monomer (m2) is 0.1 to 20% by weight, and a content of the monomer (m3) is 2 to 40% by weight, based on a total amount of monomer components constituting the monomer composition,
(m1) an alkyl(meth)acrylate monomer including an alkyl group having 1 to 20 carbon atoms, which is represented by the following formula (1),
[Chem. 1]
CH 2 ═C(R 1 )COOR 2 (1)
wherein R 1 represents a hydrogen atom or a methyl group, and R 2 represents an alkyl group having 1 to 20 carbon atoms,
(m2) an N-hydroxyalkyl(meth)acrylamide monomer having a hydroxyalkyl group having 1 to 4 carbon atoms, which is represented by the following formula (2),
[Chem. 2]
CH 2 ═C(R 3 )CONHR 4 (2)
wherein R 3 represents a hydrogen atom or a methyl group, and R 4 represents a hydroxyalkyl group having 1 to 4 carbon atoms,
(m3) a vinyl monomer having a nitrogen atom in a backbone thereof, except for the monomer (m2).
2 . The acrylic pressure-sensitive adhesive sheet according to claim 1 , wherein the monomer (m3) vinyl monomer having a nitrogen atom in a backbone thereof is at least one kind of monomer selected from N-vinyl cyclic amides represented by the following formula (3) and (meth)acrylamides:
wherein R 5 represents a divalent organic group.
3 . The acrylic pressure-sensitive adhesive sheet according to claim 1 , wherein a total content of the monomers (m1), (m2), and (m3) in the monomer composition is 80% by weight or more based on the total amount of the monomer components constituting the monomer composition.
4 . The acrylic pressure-sensitive adhesive sheet according to claim 1 , wherein an acrylic copolymer obtained by polymerizing the monomer components constituting the monomer composition has a glass transition temperature (Tg) of −10° C. or less.
5 . A method for producing an acrylic pressure-sensitive adhesive sheet, said method comprising forming the acrylic pressure-sensitive adhesive sheet having a pressure-sensitive adhesive layer (Y) on at least one face of a viscoelastic material layer (x) containing hollow microspheres, through steps of:
(i) preparing an acrylic pressure-sensitive adhesive composition comprising: a monomer composition or a partially polymerized composition thereof, including the following monomers (m1), (m2) and (m3) as essential monomer components, in which a content of the monomer (m1) is 50 to 85% by weight, a content of the monomer (m2) is 0.1 to 20% by weight, and a content of the monomer (m3) is 2 to 40% by weight, based on a total amount of monomer components constituting the monomer composition; and 0.01 to 2 parts by weight of a photopolymerization initiator based on 100 parts by weight of the monomer components;
(ii) applying the acrylic pressure-sensitive adhesive composition prepared in the step (i) on a support; and
(iii) curing the acrylic pressure-sensitive adhesive composition by irradiating an active energy ray to the acrylic pressure-sensitive adhesive composition applied on the support, thereby forming the pressure-sensitive adhesive layer (Y),
(m1) an alkyl(meth)acrylate monomer including an alkyl group having 1 to 20 carbon atoms, which is represented by the following formula (1),
[Chem. 4]
CH 2 ═C(R 1 )COOR 2 (1)
wherein R 1 represents a hydrogen atom or a methyl group, and R 2 represents an alkyl group having 1 to 20 carbon atoms,
(m2) an N-hydroxyalkyl(meth)acrylamide monomer having a hydroxyalkyl group having 1 to 4 carbon atoms, which is represented by the following formula (2),
[Chem. 5]
CH 2 ═C(R 3 )CONHR 4 (2)
wherein R 3 represents a hydrogen atom or a methyl group, and R 4 represents a hydroxyalkyl group having 1 to 4 carbon atoms,
(m3) a vinyl monomer having a nitrogen atom in a backbone thereof, except for the monomer (m2).