Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Composite having voids in a component
Reexamination Certificate
1998-10-30
2001-05-08
Copenheaver, Blaine (Department: 1771)
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Composite having voids in a component
C428S309900, C428S316600
Reexamination Certificate
active
06228476
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a coated foam insulation sheet and, in particular, to a coated foam insulation sheet, especially suited to be a duct liner, with a relatively smooth tough elastomeric coating on one or both of its major surfaces, and the method of making such a coated foam insulation sheet.
Foam sheets are used as duct liners to line air ducts and the like, especially, for applications such as a clean room air supply, where fibrous insulations can not be used to line the air ducts. In such applications, airborne dust and particles, including viruses, bacteria, pathogens and other infectious or contaminating agents, tend to collect or accumulate in any surface irregularities present on the interior surface of the duct liner and such surface irregularities increase the frictional resistance to air flow through the air ducts. Thus, there has been a need to reduce surface irregularities on such duct liners and provide a smooth tough interior surface on foam insulation sheets used as duct liners, especially open cell foam insulation sheets.
U.S. Pat. No. 4,990,370, On Line Surface and Edge Coating of Fiber Glass Duct Liners, issued Feb. 5, 1991 (hereinafter “the '370 patent”) and U.S. Pat. No. 5,211,988, Method for Preparing a Smooth Surfaced Tough Elastomeric Coated Fibrous Batt, issued May 18, 1993 (hereinafter “the '988 patent”) disclose coated fibrous batt duct liners and apparatuses for and methods of making such coated fibrous batt duct liners. The disclosures of the '370 patent and the '988 patent are hereby incorporated herein by reference in their entirety.
While the disclosures of the '370 patent and the '988 patent have been publicly available for over seven years and over five years respectively, there has remained a need for foam insulation sheet duct liners with smoother interior surfaces to reduce the accumulation of infectious agents and other contaminates on the interior surface of such duct liners and to reduce the frictional resistance to air flow through the air ducts.
SUMMARY OF THE INVENTION
The present invention provides a solution to the above problems which can be used with both closed cell and open cell foams. The foam insulation sheet of the present invention has a first major surface, e.g. The interior surface of a duct liner over which gases flow within a duct, coated with a relatively smooth, tough elastomeric coating of substantially uniform thickness. Preferably, the coating has a tough skin and penetrates into interstices of the major surface of the foam sheet to firmly bond the elastomeric coating to the foam sheet.
The coating is formed from a cross-linkable elastomeric aqueous emulsion. A cross-linkable emulsion contains monomers and polymers, some of which have multiple polymerizable sites to effect cross-linking to a three-dimensional polymer. Aqueous acrylic emulsions are preferred.
The coating is applied as a frothed cross-linkable elastomeric aqueous emulsion composition (preferably an aqueous cross-linkable acrylic latex emulsion) to one major surface of a foam insulation sheet. A doctor blade or similar means presses the emulsion composition into the interstices of the major surface of the foam insulation sheet and forms a coating layer on the major surface of the foam insulation sheet which has a generally uniform thickness and a relatively smooth surface. The cross-linkable elastomeric aqueous emulsion is then heated to cure the emulsion and form the relatively smooth tough coating.
In one embodiment of the method of the present invention, a tough skin is formed on the coating by contacting the frothed cross-linkable elastomeric aqueous emulsion composition (preferably an aqueous cross-linkable acrylic latex emulsion), applied to the major surface of the foam insulation sheet, with a hot ironing surface to dewater an exposed surface of the frothed aqueous cross-linkable acrylic latex emulsion and free bubbles from the exposed surface of the frothed aqueous cross-linkable acrylic latex emulsion, prior to curing the remainder of the frothed aqueous cross-linkable acrylic latex emulsion.
The coated foam insulation sheet duct liner of the present invention, not only has a smooth, tough coating with less irregularities for accumulating infectious agents and other contaminates, but, when compared to foam insulation sheets currently being used as duct liners, the coated foam insulation sheet of the present invention can have superior sound absorption, fire and smoke properties.
While the coated foam insulation sheet of the present invention is particularly suited for use as a duct liner, the coated foam insulation sheet of the present invention can be used for other applications where smooth, tough relatively durable surfaces are desired or required. In addition to having the first major surface coated, the foam sheet may have its lateral edges coated as well as the second major surface for certain duct liner or other applications.
REFERENCES:
patent: 5256716 (1993-10-01), Haasl et al.
patent: 5763067 (1998-06-01), Bruggemann et al.
patent: 5953818 (1999-09-01), Matthews et al.
Bogrett Blake Boyd
Feagans Royce Michael
Shumate Monroe William
Copenheaver Blaine
Johns Manville International Inc.
Lister John D.
Pratt Christopher C.
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