Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Reexamination Certificate
1999-12-16
2001-08-07
Gorr, Rachel (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Cellular products or processes of preparing a cellular...
C521S159000, C428S314400, C264S050000, C264S048000
Reexamination Certificate
active
06271276
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to polyurethane foams. This invention particularly relates to polyurethane foams prepared from aqueous polyurethane dispersions, and to a process for preparing same.
Polyurethane dispersions are known and can be useful for preparing polyurethane polymers that can themselves be useful in various applications. Polyurethane dispersions can be used, for example, to prepare coatings for leather; wood finishing; glass fiber sizing; textiles; adhesives; and automotive topcoats and primers. Polyurethane dispersions can be prepared by various processes, including, for example, those described in: U.S. Pat. No. 4,857,565; U.S. Pat. No. 4,742,095; U.S. Pat. No. 4,879,322; U.S. Pat. No. 3,437,624; U.S. Pat. No. 5,037,864; U.S. Pat. No. 5,221,710; U.S. Pat. No. 4,237,264; and, U.S. Pat. No. 4,092,286.
It is known that carpet backings can be prepared from polyurethane dispersions. For example, polyurethane dispersions prepared according to the process of U.S. application Ser. No. 09/039,978, filed Mar. 16, 1998, now abandoned, can be useful for preparing polyurethane carpet backings and polyurethane textile backings. Typically, mechanical froths of dispersions which are applied as a primary or secondary binder to a carpet backing are unstable due to high concentration of filler and the absence of foam stabilizers. Mechanical frothing to produce a stable froth requires that less filler and foam stabilizers be used, and is therefore a distinctly different process than that conventionally used to coat the back of a carpet for primary or laminate applications. Mechanical frothing of currently commercially available polyurethane dispersions using air, for example, can be carried out using additives such as, for example, stabilizing soap, inorganic filler, and wax dispersions. While foams, on casting and drying, having good physical properties and stable fine cell structure up to 10 mm thickness can be prepared, the foams so prepared are not resilient.
Resiliency is a desirable characteristic for foams used in applications such as carpet backings. Increasing the resilience of such a foam can increase both the durability and comfort of the foams. For example, a more resilient foam, or stated another way, a “springy” foam is commonly perceived as more comfortable than a non-resilient foam. A more resilient foam can also dissipate energy mechanically, by springing back, rather than as heat such as would a non-resilient foam. Dissipating energy as heat can eventually cause polymer degradation which in turn leads to the foam not returning to its original shape. When this occurs in a carpet application, the resulting pattern evident on the surface of the carpet in normal traffic areas can be perceived as premature wear.
It would be desirable, in the art of preparing polyurethane foams, to have a polyurethane dispersion composition that can be mechanically frothed such that a foam having suitable fine cell structure and good properties, including resilience, can be prepared. It would also be desirable in the art to have a process for preparing a polyurethane foam having good resilience from a polyurethane dispersions by mechanically frothing the polyurethane dispersions.
SUMMARY OF THE INVENTION
In one aspect, the present invention is a resilient polyurethane foam comprising a foam prepared by a process including the steps of frothing an aqueous polyurethane dispersion; applying the froth to a substrate; and drying the froth into a foam, wherein the polyurethane dispersion is prepared by admixing water, a chain extender, a surfactant, and a polyurethane prepolymer under mixing conditions sufficient to prepare a stable dispersion; the polyurethane is prepared from a formulation including a polyisocyanate and a polyol having a hydroxyl functionality of greater than about 2.2; and the polyurethane foam has a resiliency of from about 5 to about 80 percent.
In another aspect, the present invention is a foam backed substrate comprising a substrate and adherent thereto a resilient polyurethane foam prepared by a process including the steps of frothing an aqueous polyurethane dispersion; applying the froth to a substrate; and drying the froth into a foam, wherein the polyurethane dispersion is prepared by admixing water, a chain extender, a surfactant, and a polyurethane prepolymer under mixing conditions sufficient to prepare a stable dispersion; the polyurethane is prepared from a formulation including a polyisocyanate and a polyol having a hydroxyl functionality of greater than about 2.2; and the polyurethane foam has a resiliency of from about 5 to about 80 percent.
Frothed foams of the present invention can be useful in cushioned flooring applications such as attached cushion broadloom, carpet tiles, carpet underlay, or vinyl flooring. Frothed foams of the present invention could also be useful as cushion or absorbent layers for various textiles and disposable goods.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
In one embodiment, the present invention is a resilient polyurethane foam prepared using an aqueous polyurethane dispersion composition that can be mechanically frothed to yield a polyurethane foam having good resiliency. A polyurethane dispersion useful in the practice of the present invention includes water, and either: a polyurethane; a mixture capable of forming a polyurethane; or a mixture of both. Polyurethane-forming materials as used in the present invention are materials which can be used to prepare polyurethane polymers. Polyurethane-forming materials include, for example, polyurethane prepolymers. While polyurethane prepolymers may retain some isocyanate reactivity for some period of time after dispersion, for purposes of the present invention, a polyurethane prepolymer dispersion shall be considered as being a fully reacted polyurethane polymer dispersion. Also, for purposes of the present invention, a polyurethane prepolymer or polyurethane polymer can include other types of structures such as, for example, urea groups.
Polyurethane prepolymers useful in the practice of the present invention are prepared by the reaction of active hydrogen compounds with any amount of isocyanate in a stoichiometric excess relative to active hydrogen material. Isocyanate functionality in the prepolymers useful with the present invention can be present in an amount of from about 0.2 weight percent to about 20 weight percent. A suitable prepolymer can have a molecular weight in the range of from about 100 to about 10,000. Prepolymers useful in the practice of the present invention should be substantially liquid under the conditions of dispersal.
The prepolymer formulations of the present invention include a polyol component. Active hydrogen containing compounds most commonly used in polyurethane production are those compounds having at least two hydroxyl groups or amine groups. Those compounds are referred to herein as polyols. Representatives of suitable polyols are generally known and are described in such publications as High Polymers, Vol. XVI, “Polyurethanes, Chemistry and Technology” by Saunders and Frisch, Interscience Publishers, New York, Vol. I, pp. 32-42, 44-54 (1962) and Vol. II, pp. 5-6, 198-199 (1964); Organic Polymer Chemistry by K. J. Saunders, Chapman and Hall, London, pp. 323-325 (1973); and Developments in Polyurethanes, Vol. I, J. M. Burst, ed., Applied Science Publishers, pp. 1-76 (1978). However, any active hydrogen containing compound can be used with the present invention. Examples of such materials include those selected from the following classes of compositions, alone or in admixture: (a) alkylene oxide adducts of polyhydroxyalkanes; (b) alkylene oxide adducts of non-reducing sugars and sugar derivatives; (c) alkylene oxide adducts of phosphorus and polyphosphorus acids; and (d) alkylene oxide adducts of polyphenols. Polyols of these types are referred to herein as “base polyols”. Examples of alkylene oxide adducts of polyhydroxyalkanes useful herein are adducts of ethylene glycol, propylene glycol, 1,3-dihydroxypropane, 1,4-dihydrox
Gribble Michael Y.
Jakubowski James J.
Kennedy James G.
Schrock Alan K.
Tabor Rick L.
Bagwell M D
Gorr Rachel
The Dow Chemical Company
LandOfFree
Polyurethane foams prepared from mechanically frothed... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Polyurethane foams prepared from mechanically frothed..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Polyurethane foams prepared from mechanically frothed... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2505943