Adhesive tape

1 . A pressure-sensitive adhesive tape, comprising a base material and a pressure-sensitive adhesive layer including thermally expandable microspheres and an acrylic pressure-sensitive adhesive,

wherein the base material is a resin sheet consisting of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), polyethylene (PE), polypropylene (PP), an ethylene-propylene copolymer, an ethylene-vinyl acetate copolymer (EVA), polyamide (nylon), wholly aromatic polyamide (aramid), polyimide (PI), polyvinyl chloride (PVC), polyphenylene sulfide (PPS), a fluorine-based resin, or polyether ether ketone (PEEK),

wherein the thermally expandable microspheres are each formed of a shell and a volatile substance contained in the shell,

wherein the volatile substance includes at least one of isopentane or isooctane,

wherein the shell is formed of a resin having a glass transition temperature (Tg) of 120° C. or more,

wherein the resin for forming the shell contains a constituent unit having a carboxyl group,

wherein a difference (Tg−bp) between a boiling point (bp) of the volatile substance and the glass transition temperature (Tg) of the resin for forming the shell is 50° C. to 150° C., and

wherein a pressure-sensitive adhesive strength “c” of the pressure-sensitive adhesive tape, when a pressure-sensitive adhesive surface of the pressure-sensitive adhesive tape is bonded to a polyethylene terephthalate film after a cycle involving heating to 140° C. and then cooling to 25° C. is performed twice, is 50% or more with respect to an initial pressure-sensitive adhesive strength “a” of the pressure-sensitive adhesive tape, when the pressure-sensitive adhesive surface of the pressure-sensitive adhesive tape is bonded to the polyethylene terephthalate film under an ambient temperature of 25° C.

2 . The pressure-sensitive adhesive tape according to claim 1 , wherein a content ratio of the constituent unit having a carboxyl group is from 5 parts by weight to 97 parts by weight with respect to 100 parts by weight of the resin.

3 . The pressure-sensitive adhesive tape according to claim 2 , wherein a pressure-sensitive adhesive strength “b” of the pressure-sensitive adhesive tape, when a pressure-sensitive adhesive surface of the pressure-sensitive adhesive tape is bonded to a polyethylene terephthalate film after the pressure-sensitive adhesive tape is heated to 140° C. and then cooled to 25° C., is 50% or more with respect to an initial pressure-sensitive adhesive strength “a” of the pressure-sensitive adhesive tape, when the pressure-sensitive adhesive surface of the pressure-sensitive adhesive tape is bonded to the polyethylene terephthalate film under an ambient temperature of 25° C.

4 . The pressure-sensitive adhesive tape according to claim 1 , wherein an initial pressure-sensitive adhesive strength “a” of the pressure-sensitive adhesive tape, when a pressure-sensitive adhesive surface of the pressure-sensitive adhesive tape is bonded to a polyethylene terephthalate film under an ambient temperature of 25° C., is from 0.5 N/20 mm to 20 N/20 mm.

5 . The pressure-sensitive adhesive tape according to claim 1 , wherein a pressure-sensitive adhesive strength “b” of the pressure-sensitive adhesive tape, when a pressure-sensitive adhesive surface of the pressure-sensitive adhesive tape is bonded to a polyethylene terephthalate film after the pressure-sensitive adhesive tape is heated to 140° C. and then cooled to 25° C., is 50% or more with respect to an initial pressure-sensitive adhesive strength “a” of the pressure-sensitive adhesive tape, when the pressure-sensitive adhesive surface of the pressure-sensitive adhesive tape is bonded to the polyethylene terephthalate film under an ambient temperature of 25° C.

6 . The pressure-sensitive adhesive tape according to claim 1 , further comprising a second pressure-sensitive adhesive layer,

wherein the base material is arranged between the pressure-sensitive adhesive layer and the second pressure-sensitive adhesive layer.