Aqueous adhesive

A paper tube comprising:

• an internal paper that is spirally wound;
• and
• an external paper that is wound on an outer surface of the internal paper,
• wherein the internal paper and the external paper are bound to each other with an aqueous adhesive,
• wherein the aqueous adhesive comprises a copolymer prepared by copolymerizing:
• (A) a (meth)acrylic acid ester monomer selected from the group consisting of methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, pentyl (meth)acrylate, hexyl (meth)acrylate, cyclohexyl (meth)acrylate, octyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, tridecyl (meth)acrylate, octadecyl (meth)acrylate, biphenyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and any mixture thereof;
• and
• (B) 20 to 50 parts by mass calculated by mass based on 100 parts by mass of the (meth)acrylic acid ester monomer (A) of a styrene monomer, wherein:
• (a) the copolymerization is conducted in the presence of a polymer having (i) a chemical structure derived from a (meth)acrylic resin in an amount of from 10 to 50 parts by mass based on 100 parts by mass of the total mass of monomers and (ii) an acid value in the range of about 180 to 220 mg KOH/g as a stabilizer, and
• (b) the copolymer has a glass transition temperature in the range from about −35° C. to −20° C.,
• wherein the aqueous adhesive further comprises at least one of a crosslinking agent, a viscosity modifier, a plasticizer, an antifoaming agent, a preservative, or a colorant, and
• wherein the aqueous adhesive has a water resistance of at least 1 hour, as evaluated by no peeling at the interface of the internal paper and the external paper bond during immersion in distilled water at 60° C.