Epoxy coating system
A “hybrid” epoxy resin coating system formed by a solvent-borne epoxy resin and a water-reducible curing agent. The coating formed by this system exhibits excellent resistance to most household chemicals, and yet is permeable to water vapor transmission to reduce blistering. Although the epoxy resin is solvent-based, the total VOC content of the mixture is less than 150 grams per liter, providing a low odor mixture that is environmentally friendly. Additives in the curing agent component, including a silicone surfactant, provide a coating that adheres well even to a surface that is less than ideally prepared; no acid etching or other special surface preparation is required. All the colorant is on one side of the system, preferably in the resin component. Thus, incomplete mixing will not substantially affect the color of the finished coating. All these features make this coating system ideally suitable for use by nonprofessionals.
1. A two-part epoxy coating system comprising:
an epoxy resin component comprising a solvent, an epoxy resin, and at least one colorant, wherein the colorant comprises a reactive epoxy tint in an amount equal to about 30.82 weight percent of the epoxy resin component; and
a curing agent component comprising water and a water-reducible curing agent capable of curing the epoxy resin component and wherein the curing agent component is colorant-free.
2. The epoxy coating system of claim 1 wherein the colorant comprises a hiding pigment.
3. The epoxy coating system of claim 2 wherein the hiding pigment comprises titanium dioxide and wherein the epoxy resin component further comprises a reactive diluent, and wherein the curing agent component further comprises a silicone surfactant, an emulsifying agent comprising a nonionic surfactant, and crystalline silica.
4. The epoxy coating system of claim 3 wherein the epoxy resin comprises the reaction product of epichlorohydrin and bisphenol A, wherein the reactive diluent comprises glycidyl neodeconate, and wherein the epoxy resin component further comprises isopropyl alcohol.
5. The epoxy coating system of claim 4 wherein the epoxy resin comprises a solvent-borne liquid epoxy, and wherein the liquid epoxy is present in the epoxy resin component in the amount of from about 20 to about 25 weight percent, wherein the isopropyl alcohol is present in the epoxy resin component in the amount of from about 2.0 to about 2.25 weight percent, and wherein the titanium dioxide is present in the epoxy resin component in the amount of from about 30 to about 40 weight percent, and wherein the glycidyl neodeconate is present in the epoxy resin component in the amount of from about 9 to about 10 weight percent.
6. The epoxy coating system of claim 3 wherein the curing agent component further comprises a defoaming agent and a pigment stabilizer.
7. The epoxy coating system of claim 6 wherein the defoaming agent comprises polysiloxanes and is present in the curing agent component in the amount of from about 0.5 to about 1.0 weight percent, and wherein the pigment stabilizer comprises phosphated polyester and is present in the curing agent component in the amount of from about 0.5 to about 1.0 weight percent.
8. The epoxy coating system of claim 1 wherein the water-reducible curing agent comprises water-reducible polyamide.
9. The epoxy coating system of claim 8 wherein the water-reducible polyamide comprises a polyethylene polyamine adduct, acetic acid and 2-propoxyethanol, wherein the silicone surfactant comprises a polyether-modified dimethylpolysiloxane, wherein the nonionic surfactant comprises ethoxylated acetylenic diols.
10. The epoxy coating system of claim 9 wherein the water is present in the curing agent component in the amount of from about 30 to about 40 weight percent, wherein the water-reducible polyamide is present in the curing agent component in the amount of from about 35 to about 45 weight percent, wherein the silicone surfactant is present in the curing agent component in the amount of from about 0.5 to about 1.0 weight percent, wherein the nonionic surfactant is present in the curing agent component in the amount of from about 3.0 to about 4.0 weight percent, and wherein the silica is present in the curing agent component in the amount of from about 15 to about 20 weight percent.