Sealing gasket for closure and process for production of closure using the same

A sealing gasket for closure comprising a polyurethane elastomer obtained by reacting the following (A) and (B):

• (A) a polyisocyanate component having an isocyanate group content of 5 to 38% by weight and average 2 to 3 functional groups, obtained by modifying an aliphatic isocyanate and/or an alicyclic isocyanate, and
• (B) a polyol component having a hdyroxyl value of 20 to 350 mgKOH/g and average 2 to 3 functional groups, consisting of a mixture of a high-molecular polyol and a low-molecular polyol, wherein the high-molecular polyol is at least one member selected from polytetramethylene ether glycols and adipate polyester polyols.

A process for producing a closure, which comprises reacting the following (A) and (B) at the inner side of a closure to synthesize a polyurethane elastomer in such a state that the polyurethane elastomer is integrated with the closure:

• (A) a polyisocyanate component having an isocyanate group content of 5 to 38% by weight and average 2 to 3 functional groups, obtained by modifying an aliphatic isocyanate and/or an alicyclic isocyanate, and
• (B) a polyol component having a hydroxyl value of 20 to 350 mgKQH/g and average 2 to 3 functional groups consisting of one or more high-molecular polyol(s) wherein the one or more high-molecular polyol(s) is at least one member selected from polytetramethylene ether glycols and adipate polyester polyols.

A process for producing a closure, which comprises reacting the following (A) and (B) at the inner side of a closure to synthesize a polyurethane elastomer in such a state that the polyurethane elastomer is integrated with the closure:

• (A) a polyisocyanate component having an isocyanate group content of 5 to 38% by weight and average 2 to 3 functional groups, obtained by modifying an aliphatic isocyanate and/or an alicyclic isocyanate, and
• (B) a polyol component having a hydroxyl value of 20 to 350 mgKOH/g and average 2 to 3 functional groups, consisting of a mixture of a high-molecular polyol and a low-molecular polyol, wherein the high-molecular polyol is at least one member selected from polytetramethylene ether glycols and adipate polyester polyols.