COPOLYMER FOR PRESSURE-SENSITIVE ADHESIVE, METHOD FOR PRODUCING THE SAME AND COMPOSITION FOR PRESSURE-SENSITIVE ADHESIVE

摘要

PROBLEM TO BE SOLVED: To provide a copolymer for a pressure-sensitive adhesive, which has excellent performance balance of retaining force, tack and adhesive force and reduces melt viscosity of composition for a pressure-sensitive adhesion and the composition for pressure-sensitive adhesion.

SOLUTION: The copolymer for pressure-sensitive adhesive mainly comprises a vinyl aromatic monomer unit (a) and a conjugated diene monomer unit (b) and satisfies the following conditions that (1) the content of the vinyl aromatic monomer unit is 20-60 mass%, (2) the hydrogenation rate in the conjugated diene monomer unit is 10-50%, (3) the copolymer has two or more peaks in a molecular weight measurement in terms of polystyrene (PS) measured by a gel permeation chromatography (GPC) and (4) the molecular weight distribution (=weight-average molecular weight (Mw)/number-average molecular weight (Mn)) is ≥1.2.

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