The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Dec. 03, 1996
Filed:
Jun. 06, 1995
David W Park, Puyallup, WA (US);
Frank R Hunter, Bellevue, WA (US);
Weyerhaeuser Company, Tacoma, WA (US);
Abstract
The invention is directed to a composition of matter useful as a paper impregnant, to the method of its use, and to the products produced by the method. Poly (diphenylmethane diisocyanate) or PMDI has been used in the past as a paper impregnant with or without propylene carbonate as a diluent. These products have generally required pressing under high pressures and at elevated temperatures. It has now been found that triacetin and/or triethyl citrate in usages up to about 20% of PMDI give superior performance in impregnated products. The modified PMDI will cure at essentially ambient conditions in times as short as 1-2 days to insoluble polyureas with low residual amounts of isocyanates and reaction byproducts such as 4,4'-diaminodiphenylmethane. The treated papers can be used in applications of which skins for sandwich panels and high strength corrugated board would be exemplary.