Polyurethane foam products with controlled release of agents...

Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...

Reexamination Certificate

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C424S404000, C424S445000, C424S484000, C521S137000, C521S159000, C521S170000, C521S174000

Reexamination Certificate

active

06706775

ABSTRACT:

BACKGROUND OF THE INVENTION
The present invention relates generally to hydrophilic polyurethane foam composites used for various types of industrial, commercial, residential, personal care, cleaning and other products, and more particularly for pads, sheets, molded shapes or granules of material made of hydrophilic polyurethane foam which contains limited quantities of superabsorbent polymers to control the release of an agent or agents such as detergents, soaps, waxes, polishes, drugs, cosmetics, biologicals, volatiles and chemicals during the use thereof. Selectively abrasives can be added into or applied onto at least one surface of the formed product for additional applications and uses.
When an aqueous formulation of the present invention including superabsorbent polymer, agents and adequate water is mixed with a hydrophilic urethane prepolymer, as described in U.S. Pat. No. 5,976,847, the reaction produces polymerization and forms a hydrophilic polyurethane foam composite.
Conventional prior art urethane foam is mostly resistant and non-permeable to water. Some compositions have been treated with a surfactant in the formula to render the resultant urethane more acceptable to water. This type of surfactant-treated urethane will allow water to run along the supporting or intercellular structure but still disallow penetration into the urethane backbone.
Conventional prior art urethane foams require a stochiometric balance of water to isocyanate below approximately 0.05% addition of water or water-bearing agent in the formulation. This limits the amount of agent addition to the final composite. A further limitation of agent addition is the starting viscosity of conventional polyol components of the formula. Most additions of agent are added to the polyol component based on the high reactivity of the isocyanate component. The polyol component is typically relatively high in viscosity prior to any agent addition. Increasing its viscosity further by addition of agent quickly renders the resultant viscosity too high to pump and disallows the processing requirements of metering machinery. In addition to limited amounts of agent capable to be added is the major objection of conventional prior art urethane foams, that is, its water resistance. A composite foam product made with water-resistant or water-impermeable urethane coats or blocks the agent with its intended contact with an aqueous effluent. This defeats the original effort in adding the agent to the composite. The agent was added and intended to be available to interact with moisture bearing effluents in use.
Hydrophilic urethane foams of prior art are described in U.S. Pat. Nos. 4,137,200; 4,339,550; 5,976,847 and others, as well as in Polyurethane's Chemistry and Technology by Saunders and Frisch, Volume XVI Part 2, High Polymer Systems. The primary departure from conventional prior art non-hydrophilic urethane foam is in the polyol component. Utilizing a hydrophilic polyol reacted with isocyanate provides a hydrophilic prepolymer. Mixing said hydrophilic prepolymer with water results in a hydrophilic urethane foam. Adding an agent into the water results in a hydrophilic foam bearing the agent. If the hydrophilic foam composite including agent is subsequently contacted with an outside water-based effluent, the agent may interact with the effluent for an intended purpose. In this prior art hydrophilic foam composite technology, the contact between the agent and the effluent, or the expression of agent into effluent, is controlled by the inherent hydrophilicity of the urethane foam carrier.
For reasons above, it is needed to improve on the controlled release of agents in a urethane foam to sustain or improve the contact of agents added to composite.
SUMMARY OF INVENTION
It has been discovered that an improved controlled release urethane foam product in accordance with the present invention can be formed or obtained by combining an aqueous formulation consisting of a limited amount of superabsorbent polymer or copolymer, an agent or agents, optionally and selectively additives and adequate water with a hydrophilic urethane prepolymer. The agent or agents include, without limitation, detergents, soaps, waxes, polishes, abrasives, solid particles, drugs, cosmetics, biologicals, volatiles and chemicals. This improved composition slows and materially reduces the release of such agent or agents to a much greater extent than the known prior art products, when the pads, sheets and shaped products and granules such as sponges and particulate composition formed from such formulations are placed into use for cleaning, scrubbing, abrasion, waxing, polishing, coating, odor-controlling and absorption purposes, applications and other uses.
Thus, controlled release urethane foam product when used herein is a formed hydrophilic polyurethane foam, pad, sheet, molded shape or granular composition containing a limited quantity of superabsorbent polymer or copolymer and up to ninety percent (90%) solid filler or active agent or agents and optionally and selectively additives which, when exposed to an aqueous effluent, will enable the filler, agent or agents and additives, if any, to be gradually released for a given application or use.
DETAILED DESCRIPTION
Controlled release urethane foam products in accordance with the present invention differ from the impermeable characteristic of conventional hydrophilic urethane foam products formed in accordance with the prior art technology and are easily identifiable because of their water absorption capability in that they will swell up to one hundred fifty percent (150%) of their dry volume.
Additionally, the scrubbing and abrasive characteristic of such controlled release urethane foam products in accordance with the present invention can be designed or enhanced by adding abrasive particles to the aqueous phase during formulation of the foam products to improve the integral strength of the formed foam product.
Alternatively, an abrasive characteristic for the controlled release urethane foam product can also be obtained by forming on or laminating or adhesively bonding abrasive material to at least one exterior surface of the formed controlled release urethane foam product. The abrasive may be any composition or component that is more abrasive than the formed controlled release urethane foam product. Such laminated or adhesively bonded formed controlled release urethane foam products are particularly useful in formed foam products with a detergent agent that are used to clean hard surfaces such as pots and pans.
It has also been found that the controlled release urethane foam products formulated in accordance with the present invention, which include specific agents or additives such as biological agents or bacterial additives, can be ground or granulated to a predetermined size and, when enclosed in a filter housing, serve as a filter, for example, of noxious waste water. Another granulated form of the controlled release urethane foam product embodying a homogeneous mixture of odor control and absorption agents and a selected additive or additives will provide a litter composition for absorbing animal urine and semi-solids and for controlling noxious odors in animal litter boxes or, when placed in a suitable perforated housing or container, will control noxious odors from garbage, tobacco, diapers, vomit, liquor, gasoline, fish and other odoriferous substances.
Thus, in one aspect, the present invention covers hydrophilic polyurethane foam products with agents such as detergents, soaps, abrasives, waxes, polishes, drugs, cosmetics, biologicals, volatiles, chemicals and the like and optionally and selectively additives, formed into shaped and sized products, pads and sheets or granules in which the agents and/or additives, if any, are incorporated generally uniformly into the matrix or supporting structure of the formed foam to provide a controlled release urethane foam product formed from the reaction product obtained by combining an aqueous formulation having a limited quantity of a superabso

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