Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Reexamination Certificate
2001-12-21
2004-07-06
Cooney, Jr., John M. (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Cellular products or processes of preparing a cellular...
C521S131000, C521S134000, C521S137000, C521S170000, C521S174000
Reexamination Certificate
active
06759443
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a polyurethane foam composition, polyols and additives useful in making said foam, and methods of preparing same. In particular, the invention relates to additives comprising mixtures of polyethylene wax and polytetrafluoroethylene (PTFE) and polyols, polyisocyanates and foams containing the additive that are useful in making polyurethane shoe soles. The use of a mixture of polyethylene wax and polytetrafluoroethylene (PTFE) in the foam generating reactants results in improved properties, such as abrasion resistance in polyurethane shoe sole systems, and improved properties in the reactants used to make the foam.
BACKGROUND OF THE INVENTION
Integral skin foams are well known to those skilled in the art of polyurethane foams. Such foams have a cellular interior and a higher density microcellular or non-cellular skin. In general, to prepare such foams one reacts an organic polyisocyanate with a substance having at least one isocyanate reactive group, such as a polyol, in the presence of a catalyst, blowing agent, and a variety of optional additives. The reaction is carried out in a mold where a higher density skin forms at the interface of the reaction mixture and the relatively cool inner surface of the mold.
Integral skin foams prepared for use in shoe soles must not only have a cosmetically acceptable appearance but must also exhibit enhanced resistance to abrasion and cracking on flex. It is known in the art to add polyethylene wax to polyol components or resins which are then reacted with organic polyisocyanates to form shoe soles in order to improve abrasion resistance of the foam. Polyethylene wax is ordinarily introduced as an additive in the form of particles; such additives generally have densities ranging from 0.915 to approximately 0.96 g/cm3. The polyethylene wax provides some abrasion resistance and mold release properties, but causes processing difficulties requiring precise material handling. Polyethylene wax additives are known to separate from the polyol component resulting in lumping, filter clogging and inconsistent performance of the polyol component in polyurethane formation. Attempts to prevent separation have included homogenizing the polyol component and employing substantially constant mixing of the polyol component just prior to and during use. Use of high-speed mixers in attempts to maintain uniform dispersion of the polyethylene wax is known to increase the temperature of the polyol component to the range where melting of the polyethylene wax results. Melted polyethylene wax tends to form undesirable strands and agglomerations in the polyol component rendering it unsuitable for use in forming polyurethanes.
There is seen to be a need for an additive, for use in polyurethane shoe sole formation, that is readily dispersed in reactants prior to or during polyurethane formation, and remains dispersed for a longer period of time than the known polyethylene wax. There is also a need for an economical additive that provides easier foam processing and improves abrasion resistance of the foam shoe sole product.
An additive has been developed comprising a mixture of polyethylene wax and polytetrafluoroethylene (PTFE) which meets the above needs and surprisingly it has been found that foams comprising the additive have markedly enhanced abrasion resistance.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a flexible, low density, integral skin polyurethane foam capable of use in shoe sole applications, wherein the foam comprises polyethylene and PTFE, in an effective amount to improve abrasion resistance. It is a further object of the invention to provide polyurethane foam capable of use in shoe sole applications comprising about 0.3 to 2 weight percent of the mixture, preferably from about 0.5 to about 1.5 weight percent mixture, most preferably from about 1.0 to about 1.2 weight percent.
It is an object of the invention to provide an additive useful in the production of polyurethane foam comprising a mixture of polyethylene or PTFE. It is a further object of the invention to provide an additive comprising a polyisocyanate component or a resin having polyisocyanate reactive groups, e.g., a polyol component, said component having dispersed therein a polyethylene/PTFE mixture. It is a further object of the invention to provide an additive wherein the density of the polyethylene/PTFE mixture is similar to the density of the component to which it is added such that the additive dispersed in the component has a decreased tendency to separate from the component.
It is an object of the invention to provide a composition of matter comprising a polyol component comprising at least one polyoxyalkylene polyether polyol, and an additive comprising a mixture of polyethylene and PTFE wherein the mixture has a density from greater than 0.97 to about 1.1 times the density of the polyol component, from about 1.0 to about 1.1.
It is also an object of the invention to provide the composition of matter wherein said mixture comprises particles having a maximum particle size of less than 125 microns. It is also an object of the invention to provide the composition of matter wherein said mixture comprises particles having a mean particle size from about 1 microns to about 25 microns. It is preferred that the mixture comprises a homogeneous blend of said polyethylene and PTFE.
It is a further object of the invention to provide an additive for a polyol component useful in making polyurethane comprising at least one polyoxyalkylene polyether carrier polyol and a mixture comprising polyethylene and PTFE wherein said mixture has a density ranging from greater than 0.97 to about 1.1 times the density of the polyol component, preferably ranging from about 1.0 to about 1.1, and a ratio of the at least one polyoxyalkylene polyether carrier polyol to the mixture from about 1:1 to about 1:10. It is a further object of the invention to provide the additive with mixture in amounts ranging from 0.1 to 12 weight percent based on the total amount of the at least one polyoxyalkylene polyether polyol.
It is a further object of the invention to provide an additive for a polyisocyanate component useful in making polyurethane comprising an organic polyisocyanate or organic polyisocyanate prepolymer and a mixture comprising polyethylene and PTFE wherein said mixture has a density ranging from greater than 0.97 to about 1.1 times the density of the polyisocyanate component, preferably ranging from about 1.0 to about 1.1, and a ratio of the polyisocyanate carrier to the mixture from about 1:1 to about 1:10. It is a further object of the invention to provide the additive with mixture in amounts ranging from 0.1 to 12 weight percent based on the total amount of the polyisocyanate component.
It is a further object of the invention to provide a polyurethane foam composition comprising the reaction product of an organic polyisocyanate, an isocyanate reactive composition comprising one or more vinyl polymer grafted polyoxyalkylene polyether dispersions or polyoxyalkylene polyether polyols; reacted in the presence of a urethane promoting catalyst; a blowing agent; an additive comprising a mixture of polyethylene and PTFE, and optionally, a carrier comprising a polyoxyalkylene polyether polyol or an organic polyisocyanate, and optionally, surfactants, fillers, pigments, antioxidants, and stabilizers. It is a yet further object of the invention to provide such a foam with an amount of mixture effective to improve abrasion resistance, preferably from about 0.1 to about 12 weight percent based on the sum of the weights of components of the isocyanate reactive composition. It is a yet further object of the invention to provide a polyurethane foam reaction product wherein the mixture has a density ranging from greater than 0.97 to about 1.1 times the density of the isocyanate reactive composition, preferably from about 1.0 to about 1.1.
It is a further object of the invention to provide a molded integral skin polyurethane article havin
Brant Gary
Todoroski Dragoljub
BASF Corporation
Borrego Fernando A.
Cooney Jr. John M.
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