Browse Prior Art Database

SOLVENT-BORNE INDUSTRIAL COATINGS CONTAINING CELLULOSE ESTERS WITH IMPROVED SAG RESISTANCE

IP.com Disclosure Number: IPCOM000146159D
Publication Date: 2007-Feb-06
Document File: 9 page(s) / 69K

Publishing Venue

The IP.com Prior Art Database

Related People

EASTMAN CHEMICAL COMPANY: OWNER [+4]

Abstract

This invention provides a method for formulating a high solids, volatile organic compound (VOC) compliant coating composition comprising at least one epoxy polymer, at least one mixed cellulose ester, and at least one curing agent, wherein the coating composition has improved sag resistance without negatively impacting the viscosity, VOC, or solids content of the coating system. This coating composition can be utilized in the industrial market which includes heavy industrial, industrial maintenance, and marine.

This text was extracted from a PDF file.
This is the abbreviated version, containing approximately 18% of the total text.

Page 1 of 9

SOLVENT-BORNE INDUSTRIAL COATINGS CONTAINING CELLULOSE ESTERS WITH IMPROVED SAG RESISTANCE

BY: ALLEN M. CHEEK AND CARL J. LONG, II EASTMAN CHEMICAL COMPANY

ABSTRACT

This invention provides a method for formulating a high solids, volatile organic compound (VOC) compliant coating composition comprising at least one epoxy polymer, at least one mixed cellulose ester, and at least one curing agent, wherein the coating composition has improved sag resistance without negatively impacting the viscosity, VOC, or solids content of the coating system. This coating composition can be utilized in the industrial market which includes heavy industrial, industrial maintenance, and marine.

BACKGROUND:

In the industrial market, high film build coatings are desired for metal protection against corrosion. In this case, corrosion resistance is achieved by barrier properties. More restrictive VOC regulations have limited the amount of solvent that can be used in coatings. At low VOC concentrations, viscosity can sometimes be a factor, as highly viscous coating systems limit application methods available to apply the coatings. To comply with VOC regulations, low molecular weight resins in high solids coating compositions can usually be formulated at viscosity levels which are suitable for application without diluting with solvent. This is possible due to the lower viscosities of the lower molecular weight resins. These coating systems, however, typically have significant sag and settling. Thus, a high solids coating composition must be of sufficiently low viscosity to be applied by power sprayers
yet sufficiently sag-resistant to permit a reasonably thick coating upon a vertical metal substrate without sagging.

For conventional, higher VOC epoxy coatings, thixotropic agents have been used, such as, fumed silica, organomodified clays, cellulose acetate butyrate (CAB), and microgels to control sagging. Previous patents, such as, European Patent Publication No. 0249200 A2 noted that one method to control sagging in cycloaliphatic epoxy resin coatings before curing is to use a high molecular weight polymer, such as, cellulose acetate butyrate, phenoxy resins, vinyl chloride-vinyl acetate copolymers, or terpolymer resins. This patent application notes that this method is unacceptable for high solids coatings since the high molecular weight polymers are often sufficient to control sag, but they lead to higher viscosity, which requires addition of more solvent, which once again leads to higher sag and higher VOC concentrations. U.S. Patent 5,034,444 notes that for a thixotrope agent to be effective in a high solids coating composition, it must provide the desired rheological properties while avoiding undesired side effects, such as, excessive viscosity buildup. This patent further states that when cellulose acetate butyrate is used as a thixotropic agent, it imparts undesirably high viscosity levels in the coating system...