Coating agent composition and method for coating structure

A coating agent composition, the composition comprising:

• (A) an organopolysiloxane resin that is solid at 25° C., including a siloxane unit represented by the general formula:
• R13SiO1/2 and a siloxane unit represented by the formula:
• SiO4/2, a molar ratio of the siloxane unit represented by the general formula:
• R3SiO1/2 to the siloxane unit represented by the formula:
• SiO4/2 being from 0.5 to 1.2, wherein R1s are the same or different unsubstituted or halogen-substituted monovalent hydrocarbon groups having 1 to 12 carbon atoms;
• groups represented by the general formula:
• X(3-a)R2aSiO—
• wherein R2s are the same or different unsubstituted or halogen-substituted monovalent hydrocarbon groups having 1 to 12 carbon atoms, X is a hydrolyzable group, and “a” is 0, 1, or 2;
• groups represented by the general formula:
• X(3-a)R3aSi—[R4—SiR32(OSiR32)mOSiR32]n—R4—
• wherein R3s are the same or different unsubstituted or halogen-substituted monovalent hydrocarbon groups having 1 to 12 carbon atoms and no aliphatic unsaturated bond, R4s are the same or different alkylene groups having 2 to 12 carbon atoms, X and “a” are the same as described above, “m” is an integer of 0 to 10, and “n” is 0 or 1;
• hydrogen atoms, or hydroxyl groups;
• (B) an organopolysiloxane that is liquid at 25° C., including in a molecule at least two silicon atom-bonded groups represented by the general formula:
• X(3-a)R2aSiO—
• wherein R2, X, and “a” are the same as described above;
• groups represented by the general formula:
• X(3-a)R3aSi—[R4—SiR32(OSiR32)mOSiR32]n—R4—
• wherein R3, R4, X, “a”, “m”, and “n” are the same as described above;
• or hydroxyl groups, in an amount such that a mass ratio of component (A):component (B) is from 45:55 to 80:20;
• (C) a silane compound represented by the formula:
• R2(4-b)SiXb
• wherein R2 and X are the same as described above, and “b” is 2, 3, or 4;
• or a partially hydrolyzed condensate thereof, in an amount of from 0.1 to 30 parts by mass with respect to 100 parts by mass of the total of components (A) and (B);
• (D) a condensation reaction catalyst for accelerating curing of the composition;
• and
• (E) an organic solvent, in an amount of from 20 to 2,000 parts by mass with respect to 100 parts by mass of the total of components (A) and (B).