Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From reactant having at least one -n=c=x group as well as...
Reexamination Certificate
2000-06-19
2002-11-12
Seidleck, James J. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From reactant having at least one -n=c=x group as well as...
C528S071000, C524S840000, C428S423400, C428S208000, C428S425500, C428S423500, C428S423700, C442S080000, C442S082000
Reexamination Certificate
active
06479612
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to fluorochemical compositions which provide oil repellency and water repellency properties to substrates. This invention further relates to a method for imparting oil- and water-repellent properties to various substrates and the resulting treated substrates.
BACKGROUND OF THE INVENTION
The tanning of leather is a complex process described, for instance, in the Kirk-Othmer Encyclopedia of Chemical Technology. Fourth Edition, Volume 15, pp. 159-176. Produced from animal skins, leather is used for many purposes, including shoes, upholstery, clothing, gloves, hats, books, sports equipment, and the like. In most such uses, water repellency is desired and conventionally achieved by the application of fats, or by surface treatment of the leather after drying. The application of fat to the leather does not provide any oil repellency. Oil repellency for leather, and thereby soil repellency, is also a desirable property in most of these uses but is more difficult to produce. Limited oil repellency can be obtained by certain surface coatings after the leather has been dried. Such surface applications to dried leather do not penetrate, or penetrate only to a limited extent, throughout the thickness of the leather and thus do not provide significant oil or water repellency in depth through the thickness of the leather. Consequently, when the leather is cut in the manufacture of articles, or when the surface of finished articles is damaged by abrasion in use, the exposed leather is deficient in oil repellency and soil resistance. Additionally, the post-drying surface finishing of leather is an art in itself, and any coatings must be compatible with the final treatments given to leathers in various uses.
Incorporation of oil repellent materials onto the dried leather hides by spraying or into the hides during the wet stage processing, e.g., during the tanning, retanning, and dyeing baths, is practical and in use in the leather industry. However the leather, after drying and processing to produce the desired repellency, either requires a high temperature cure at about 100° C. or lengthy storage time (about 2 weeks) at room temperature.
A number of treatment processes have been described for improving the water- and oil-repellency of leather, for instance, Diesenroth, et al, in U.S. Pat. No. 5,693,747 describe sulfur-containing diols capable of being reacted with urethanes to make repellent materials. Certain of Deisenroth's compositions contain an organic sulfate group, but do not contain sulfonate groups.
It is desirable to provide fluorochemical oil- and water-repellent formulations that are compatible with the wet stages of leather processing, and that would, after drying and fabrication of finished leather products, provide oil and water repellent properties immediately and without a cure step substantially throughout the thickness of the leather. Furthermore, it is desirable that such bath additives be effective with essentially no changes in the leather processing steps, be compatible with leather treatment bath formulations, and be applied without the need for additional equipment. The present invention provides such a bath additive. Further, such compounds provide oil repellency and water repellency to other substrates.
SUMMARY OF THE INVENTION
The present invention comprises a polymer having at least one urea linkage derived by contacting (1) at least one polyisocyanate, or mixture or polyisocyanates, (2) at least one fluorocarbon alcohol, fluorocarbon thiol or fluorocarbon amine, (3) at least one straight or branched chain alcohol, amine or thiol, (4) at least one alcohol containing a sulfonic acid group or its salt, and then (5) optionally at least one linking agent.
The present invention further comprises a method of imparting oil repellency and water repellency to leather, wood, masonry and textile substrates comprising contacting said substrate with the polymer described above. The present invention further comprises substrates having oil repellency and water repellency treated with a polymer as described above.
DETAILED DESCRIPTION OF THE INVENTION
Trademarks and tradenames are indicated herein by capitalization. The present invention comprises urethane-based polymers that can be applied during the wet treatment, tanning, or bath stage of leather processing, providing oil- and water-repellent properties and soil resistance substantially throughout the thickness of the leather. The dispersions are compatible with conventional leather treatment processes without process changes and are superior to surface coating of treated leather. The polymers are also useful to impart oil repellency and water repellency to wood, masonry and textile substrates.
The urethane-based oil- and water-repellent polymers of the present invention comprise branched polymers having at least one urea linkage per molecule and are derived by contacting (1) at least one polyisocyanate, or mixture of polyisocyanates, which predominately contains at least three isocyanate groups per molecule, (2) at least one fluorocarbon alcohol, fluorocarbon thiol, or fluorocarbon amine, (3) at least one branched or straight chain alcohol, amine, or thiol, (4) at least one alcohol containing a sulfonic acid group or the salt of a sulfonic acid group, and (5) optionally sufficient liking agent to react with all remaining isocyanate groups. These are hereinafter identified as Reactants 1-5. By the term “polyisocyanates” is meant tri- and higher isocyanates and the term includes oligomers.
The polyisocyanate reactant (Reactant 1) provides the branched polymer backbone of the polymer. Any polyisocyanate having predominately three or more isocyanate groups, or any isocyanate precursor of a polyisocyanate having predominately three or more isocyanate groups, is suitable for use in this invention. It is recognized that minor amounts of diisocyanates may remain in such products. An example of this is a biuret containing residual small amounts of hexamethylene diisocyanate. Particularly preferred as Reactant 1 are hexamethylene diisocyanate homopolymers having the structure of Formula 1.
wherein k averages about 1.8. These are commercially available, for instance as DESMODUR N-100 from Bayer Corporation, Pittsburgh Pa. DESMODUR N-100 is a hexamethylene diisocyanate-based polymeric isocyanate containing biuret groups. While individual homopolymers having k=1, 2, etc., are suitable for preparing the polyurethane polymers of the present invention, this specific homopolymer is only available in admixture with substantial amounts (50% or more) of homopolymers having k greater than 1, i.e., substantial amounts of tetra- and higher polyisocyanates.
Also suitable for use as Reactant 1 are hydrocarbon diisocyanate-derived isocyanurate trimers which can be represented by Formula 2.
wherein R is a divalent hydrocarbon group, preferably aliphatic, alicyclic, aromatic, or arylaliphatic. For example, R is hexamethylene, toluene, or cyclohexylene, and is preferably hexamethylene, which is available as DESMODUR N-3300 (a hexamethylene diisocyanate-based isocyanurate). Other triisocyanates useful for the purposes of this invention are those obtained by reacting three moles of toluene diisocyanate with 1,1,1-tris-(hydroxymethyl)ethane or 1,1,1-tris-(hydroxymethyl)propane. The isocyanurate trimer of toluene diisocyanate and that of 3-isocyanatomethyl-3,4,4-trimethylcyclohexyl isocyanate are other examples of triisocyanates useful for the purposes of this invention, as is methine-tris-(phenylisocyanate). Precursors of polyisocyanate, such as disocyanate, are also suitable for use in the present invention as substrates for the polyisocyanates.
Preferred polyisocyanate reactants are the aliphatic and aromatic polyisocyanates containing biuret structures. Most preferred is the homopolymer of hexanethylene diisocyanate, DESMODUR N-100.
The fluorocarbon alcohol, fluorocarbon thiol, or fluorocarbon amine (Reactant 2) provides the oil- and soil-repellency and contributes to the water repellency of th
Del Pesco Thomas Wayne
Kirchner Jack
Liu Andrew H.
Bissett Melanie
E. I. du Pont de Nemours and Company
Seidleck James J.
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