Polyether-modified siloxane, coating additive, coating composition, coating agent, coating layer, and method for producing polyether-modified siloxane

A method for producing a polyether-modified siloxane represented by an average composition formula (1):

• (R3SiO1/2)a(R2R′SiO1/2)a′(R2SiO2/2)b(RR′SiO2/2)b′(RSiO3/2)c(SiO4/2)d (1)
• wherein in the formula (1), “R”s are each independent, are identical to or different from one another, and each represent a hydrogen atom, a hydroxy group, a monovalent hydrocarbon group having 1 to 18 carbon atoms, or an alkoxy group having 1 to 10 carbon atoms, “R”'s are each independent, are identical to or different from one another, and each represent an organic group selected from groups represented by —CqH2q—O—(C2H4O)e(C3H6O)f—R1, R1s are each independent, are identical to or different from one another, and each represent a hydrogen atom, a hydrocarbon group having 1 to 30 carbon atoms, or an organic group represented by R6—(CO)—, R6 represents a hydrocarbon group having 1 to 30 carbon atoms, “a”, “a′”, “b”, “b′”, “c”, and “d” respectively satisfy 0≤a≤15, 0≤a′≤15, 5≤b≤1000, 0≤b′≤50, 1≤c≤10, 0≤d≤5, and 2≤a′+b′≤50, “e” and “f” respectively satisfy 2≤e≤200 and 0≤f≤200, “q” satisfies 2≤q≤10, and 2≤e+f≤200, the method comprising the following steps (I) and (II), wherein
• step (I) is a step of using:
• a compound represented by an average composition formula (2);
• and
• a compound represented by an average composition formula (3) and/or a compound represented by an average composition formula (4):
• (R″3SiO1/2)g(R″2SiO2/2)h(R″SiO3/2)i(SiO4/2)j (2)
• wherein in the formula (2), “R″”s are each independent, are identical to or different from one another, and each represent a hydroxy group or a monovalent hydrocarbon group having 1 to 18 carbon atoms, 0≤g≤10, 0≤h≤100, 1≤i≤30, and 0≤j≤8;
• (R″2SiO2/2)k(R″HSiO2/2)l (3);
• (R″3SiO1/2)m(R″2HSiO1/2)n(R″2SiO2/2)o(R″HSiO2/2)p (4)
• wherein in the formulae (3) and (4), “R″”s are as described above, and 0≤k≤6, 0≤1≤6, 0≤m≤2, 0≤n≤2, 0≤o≤500, 0≤p≤100, 3≤k+1≤8, n+m=2, and 0≤o+p≤500;
• to synthesize a compound represented by an average composition formula (5):
• (R″3SiO1/2)a(R″2HSiO1/2)a′(R″2SiO2/2)b(R″HSiO2/2)b′(R″SiO3/2)c(SiO4/2)d (5)
• wherein in the formula (5), “R″”, “a”, “a”, “b”, “b″”, “c”, and “d” are as described above, and
• step (II) is a step of causing a reaction between
• the compound of the formula (5) and
• a compound represented by an average composition formula (6):
• CH2═CX—CrH2r—O—(C2H4O)e(C3H6O)f—R1 (6)
• wherein in the formula (6), R1, “e”, and “f” are as described above, X represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 5 carbon atoms, and 0≤r≤8.