Mask adhesive and pellicle comprising same

A mask adhesive comprising:

• 100 parts by mass of a thermoplastic elastomer (A) in which a loss tangent measured from −80° C. to 200° C. at a frequency of 1 Hz has a maximum value at a temperature of −20° C. to 30° C.;
• 20 to 150 parts by mass of a tackifier resin (B);
• and
• 20 to 150 parts by mass of a process oil (C), wherein
• an amount of softening agent selected from the group consisting of polybutene, hydrogenated polybutene, unsaturated polybutene, aliphatic hydrocarbons (excluding the process oil (C)), and acrylic polymers is 0 to 1 part by mass relative to 100 parts by mass of the thermoplastic elastomer (A),
• the thermoplastic elastomer (A) is at least one selected from the group consisting of a styrene-based thermoplastic elastomer, a (meth)acrylate-based thermoplastic elastomer, and an olefin-based thermoplastic elastomer,
• in the process oil (C), a total of a proportion (% CP) of paraffin carbon and a proportion (% CN) of naphthene carbon is 50% or more,
• in a molecular-weight distribution chart obtained by gel permeation chromatography of the process oil (C), a ratio of an area of a region where the molecular-weight is 500 or less is 5% or less,
• in the mask adhesive, a loss tangent measured from −80° C. to 200° C. at a frequency of 1 Hz has a maximum value at a temperature of −10° C. to 30° C., and
• the mask adhesive has a sulfur content of 300 μg/g or less.