Pressure-sensitive adhesive composition and surface protection sheets including the same

An acrylic pressure-sensitive adhesive composition comprising an acrylic polymer produced by free radical polymerization,

• wherein the acrylic polymer has a weight-average molecular weight (Mw) of less than 830 kDa;
• wherein a relative peak width at half height (PWHH) of the acrylic polymer is 1.75 or less or wherein the acrylic polymer has an entanglement molecular weight (Me) of less than 50 kg/mol,
• the relative peak width at half height (PWHH) of the acrylic polymer being the ratio of an absolute peak width at half height (PWHH) of the acrylic polymer determined from differentiated DSC signal of the acrylic polymer at the glass transition temperature (Tg) to an absolute peak width at half height (PWHH) of a reference acrylic polymer obtained by reacting ethyl acrylate and acrylic acid in a weight ratio of 100:5 with 10 mmol/l AIBN, wherein the absolute peak width at half height (PWHH) of the reference acrylic polymer is determined in the same manner as the absolute peak width at half height (PWHH) of the acrylic polymer, and
• Me being calculated from a plateau modulus determined by rheological methods;
• and
• wherein, when the acrylic polymer comprises one or more alkyl (meth)acrylates having an alkyl group with more than 4 carbon atoms as a monomer component, their amount is less than 40 parts by weight with respect to 100 parts by weight of the total amount of monomer components.