Epoxy resins and silane aqueous co-dispersions and the uses thereof
View Patent ↗The process to prepare a storage stable aqueous co-dispersion of epoxy resins and at least a silane oligomer is given. This aqueous co-dispersion of epoxy resins with a silane as part A, of a curable paint composition in which the part B comprises a hardener and optionally pigments and additives. This epoxy resins with the silane provide equal performance even after several months' storage.
1. A process for making a storage stable aqueous co-dispersion comprising:
emulsifying at least one silane or silane oligomer in the presence of an emulsifier at a temperature between 20° C. and 65° C., to form a silane or silane oligomer emulsion; and
blending the silane or silane oligomer emulsion with an epoxy resin emulsion or an epoxy resin dispersion at room temperature, to form the aqueous co-dispersion;
wherein the epoxy resin of the epoxy resin emulsion and the epoxy resin dispersion comprises a liquid or solid bisphenol type epoxy resin having an epoxy equivalent weight of about 180 to about 3500.
2. The process of claim 1 , wherein the silane oligomer comprises an epoxy silane oligomer formed from an epoxy silane monomer or a combination of an epoxy silane monomer and other monomeric silanes; wherein the epoxy silane is selected from the group consisting of a glycidoxy silane having 2 or 3 functional alkoxy groups, and a cycloaliphatic epoxy silane having 2 or 3 functional alkoxy groups; and wherein the other monomeric silanes have organofunctional features selected from the group consisting of vinyl, methacryl, alkyl, and polyalkyleneoxide, with the proviso that the organofunctional features do not interact with epoxy functionalities.
3. The process of claim 1 , wherein the liquid or solid bisphenol type epoxy resin is obtained by condensation between bisphenol A or bisphenol F and epichlorohydrin.
4. The process of claim 1 , wherein the emulsifying of the at least one silane or silane oligomer is performed by an inversion emulsion method or a solid addition emulsion method.
5. A process for making a curable composition comprising:
making a storage stable aqueous co-dispersion according to the process of claim 1 ;
optionally combining at least one of pigment, filler, and additives with the aqueous co-dispersion;
and combining the aqueous co-dispersion with a water compatible curing agent;
wherein the water compatible curing agent optionally contains at least one of pigment, filler and additives.
6. The process of claim 5 wherein the pigment and additives are combined with the aqueous co-dispersion.
7. The process of claim 5 , wherein the aqueous co-dispersion is aged for at least 6 months at room temperature prior to the optional and required combining steps.
8. The process of claim 5 , further comprising adding a catalyst to the curable composition, wherein the catalyst is selected from the group consisting of tertiary amine and phenol.
9. A curable composition formed by the process of claim 5 , wherein the curable composition is a paint formulation capable of providing, when cured, corrosion protection to steel panels after 500 hours of salt spray exposure.
10. The paint formulation of claim 9 , further comprising at least one additive selected from the group consisting of primary pigments, extender pigments, anti-corrosive pigments, surfactants, antifoam agents, rheology modifiers, mar reagents, and slip reagents.