Pressure-sensitive adhesive composition

A pressure-sensitive adhesive comprising the following pressure-sensitive adhesive composition which has been heated to about 100.degree. to about 180.degree. C. for about 40 seconds to about 5 minutes:

• (i) a liquid diene polymer containing in the molecule thereof an average of about 2.0 to about 2.5 functional groups capable of reacting with the isocyanate,
• (ii) an isocyanate compound containing therein 2 or more isocyanate groups in the molecule thereof, and
• (iii) a tackifier, wherein an anionic surface active agent (iv) is present in an amount of about 0.2 to about 10 parts by weight per 100 parts by weight of the total weight of said liquid diene polymer and isocyanate compound, said anionic surface active agent being selected from the group consisting of
• (a) carboxylates represented by the formulae ##STR10## (b) sulfonates represented by the formulae ##STR11## (c) sulfate salts represented by the formulae ##STR12## (d) alkyl phosphoric acid diester salts having 1 to 18 carbon atoms in the alkyl moiety thereof;
• and
• (e) alkylphenol type phosphoric acid diester salts having 1 to 18 carbon atoms in the alkyl moiety thereof wherein, R, R' and R" are branched or straight chain hydrocarbons having 1 to 18 carbon atoms.