Epoxy siloxane coating compositions

An epoxy-polysiloxane polymer coating composition comprising:

• water;
• from 20% to 80% by weight of a polysiloxane having the formula
• where,
• (a) each R1 is independently selected from a hydroxy group or an alkyl, aryl, or alkoxy group having up to six carbon atoms,
• (b) each R2 is independently selected from hydrogen or an alkyl or aryl group having up to six carbon atoms, and
• (c) n is selected so that the molecular weight for the polysiloxane is 400 to 10,000;
• from 20% to 80% by weight of a non-aromatic epoxide resin comprising more than one 1,2-epoxide group per molecule and an epoxide equivalent weight of 100 to 5,000;
• up to 15% by weight of a cure accelerator comprising a tin catalyst in the form of an octanoate, a dodecanoate or a naphthanate;
• up to 15% by weight of a flexible epoxy resin based on the glycidyl ether of castor oil having an epoxide equivalent weight of 200 to 1,000;
• and
• from 5% to 40% by weight of a cure system comprising a blend of at least one trialkoxy functional aminosilane and at least one amino functional polysiloxane resin, wherein the trialkoxy functional aminosilane has a general formula
• and the amino functional polysiloxane resin has a general formula
• where,
• (a) R5 is a difunctional organic radical selected from an aryl, an alkyl, a dialkylaryl, an alkoxyalkyl, an alkylaminoalkyl, or a cycloalkyl radical,
• (b) each R6 is independently selected from an alkyl, a hydroxyalkyl, an alkoxyalkyl, or a hydroxyalkoxyalkyl group containing less than six carbon atoms,
• (c) each R8 is a difunctional organic radical independently selected from an aryl, alkyl, dialkylaryl, alkoxyalkyl, alkylaminoalkyl, or cycloalkyl radical,
• (d) each R9 is independently selected from an aryl, phenyl, (C1-C4)alkyl, (C1-C4)alkoxy, or —OSi(R10)2R8NH2 group, wherein R8 of the formula —OSi(R10)2R8NH2 is a difunctional organic radical independently selected from an aryl, alkyl, dialkylaryl, alkoxyalkyl, alkylaminoalkyl, or cycloalkyl radical, and each R10 of the formula —OSi(R10)2R8NH2 is independently an aryl, phenyl, (C1-C4)alkyl, (C1-C4)alkoxy, or —OSi(R9)2R8NH2 and
• (e) m is selected so that the blend has an amine equivalent weight ranging from 112 to 250 g/NH, and an average alkoxy functionality value of 2.2 to 2.8,
• wherein the blend is added in an amount sufficient to provide an amine equivalent to epoxide equivalent of 0.7:1.0 to 1.3:1.0 in the coating composition.

A method for coating the surface with a coating composition, the method comprising:

• preparing a resin component comprising:
• water;
• a polysiloxane having the formula
• where,
• (a) each R1 is independently selected from a hydroxy group or an alkyl, aryl, or alkoxy group having up to six carbon atoms,
• (b) each R2 is independently selected from hydrogen or an alkyl or aryl group having up to six carbon atoms, and
• (c) where n is selected so that the molecular weight for the polysiloxane is 400 to 10,000;
• and
• a non-aromatic epoxide resin comprising more than one 1,2-epoxide group per molecule and an epoxide equivalent weight in the range of 100 to 5,000;
• adding a cure system to the resin component to form a fully cured epoxy-modified polysiloxane coating composition, the cure system comprising:
• a blend of at least one trialkoxy functional aminosilane and at least one amino functional polysiloxane resin;
• and
• optionally a cure accelerator comprising at least one metal catalyst,
• where the blend has an average alkoxy functionality value of 2.2 to 2,8;
• and
• applying the coating composition to a surface of a substrate to be protected before the coating composition becomes fully cured,
• wherein the coating composition protects the surface of the substrate from the undesired effects of one or more chemicals, corrosion and weather.

An epoxy-polysiloxane polymer coating composition comprising:

• water;
• a polysiloxane having the formula
• where,
• (a) each R1 is independently selected from a hydroxy group or an alkyl, aryl, or alkoxy group having up to six carbon atoms,
• (b) each R2 is independently selected from hydrogen, or an alkyl or aryl group having up to six carbon atoms, and
• (c) n is selected so that the molecular weight for the polysiloxane is 400 to 10,000;
• a non-aromatic epoxide resin having more than one 1,2-epoxide group per molecule with an epoxide equivalent weight of 100 to 5,000;
• a flexible epoxy resin based on the glycidyl ether of castor oil having an epoxide equivalent weight of 200 to 1,000;
• and
• a cure system comprising a blend comprising at least one trialkoxy functional aminosilane and at least one amino functional polysiloxane resin, where the blend has an alkoxy content of 10% by weight to 25% by weight.