NOVELTY - A heat-resistant resin comprises homopolymer or copolymer of structure monomer chosen from acrylic acid or acrylic acid ester (I), and copolymer of structure monomer chosen from acrylic acid ester and/or acrylic acid, methacrylic acid ester and/or methacrylic acid and acrylic acid-methacrylic acid. The sum total of the methacrylic acid ester and methacrylic acid is 30 mol% or less.    USE - Heat-resistant resin is used for adhesive agent, separator, solid electrolyte and insulating contact-bonding layer for electrical storage device e.g. lithium-ion secondary battery, lithium-ion capacitor, electrical double layer capacitor, solid sulfide battery, solid oxide battery, and thin film battery (all claimed).    ADVANTAGE - The adhesive agent, separator, solid electrolyte and insulating contact-bonding layer obtained heat-resistant resin have excellent heat resistance, oxidation resistance and reduction resistance. The solid electrolyte obtained by the heat-resistant resin has excellent shape-retention property. The electrical storage device has excellent reliability.    DETAILED DESCRIPTION - A heat-resistant resin comprises homopolymer or copolymer of structure monomer chosen from acrylic acid or acrylic acid ester of formula: CH2=C(-R)-C(=O)-O-R1 or acrylic acid, and copolymer of structure monomer chosen from acrylic acid ester and/or acrylic acid, methacrylic acid ester and/or methacrylic acid and acrylic acid-methacrylic acid. The sum total of the methacrylic acid ester and methacrylic acid is 30 mol% or less.    R1=at least one carbon, in which R1 bonded by carbon with ester bond, and carbon bonded by ester bond is primary or secondary carbon or H;and    R=H or CH3.    INDEPENDENT CLAIMS are included for the following:    (1) adhesive agent;    (2) insulating contact-bonding layer;    (3) separator;    (4) solid electrolyte; and    (5) electrical storage device.    DESCRIPTION OF DRAWING(S) - The drawing shows a front sectional view of the electrical double layer capacitor.    Positive electrode package electrode (61)    Negative electrode package electrode (62)    Package (70)    Cover component (70a)    Base portion (70b)