Compositions – Humidostatic – water removive – bindive – or emissive
Reexamination Certificate
2001-04-04
2003-07-08
Anthony, Joseph D. (Department: 1714)
Compositions
Humidostatic, water removive, bindive, or emissive
C210S689000, C210S502100, C062S085000, C062S114000, C062S475000, C062S476000, C521S052000, C521S054000, C521S099000, C521S122000, C521S123000, C570S179000, C570S262000
Reexamination Certificate
active
06589444
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to novel desiccant compositions comprised of certain drying agents and binders and a method for separating, drying and/or filtering chemical mixtures. The composition and method of the invention have broad applicability. They may be used for example to remove water from chemical mixtures like refrigerants (e.g., in vehicular air conditioning systems), air (e.g, in vehicular braking systems), natural gas and cleaning solvents (e.g., in semiconductor manufacture and pipeline cleaning).
BACKGROUND OF THE INVENTION
A number of methods have been developed in order to separate water from chemical mixtures. The known methods include the use of alkaline earth compounds, carbon molecular sieves, oleum, distillation, and membranes. Many of the known methods are disadvantageous because the processes are inefficient or uneconomical; the drying agents undergo undesirable side reactions and/or adsorbs or absorbs the material being dried (See, U.S. Pat. No. 5,347,822).
Drying agents used principally in connection with circulating refrigerants include activated aluminum oxide, silica gels and molecular sieves in solid or granulated form. During use, these materials are abraded by the flow of the cooling liquid and mechanical vibrations and form dust particles. In order to prevent the dust from clogging the valves and conduits of the refrigeration system, a filter must be employed. This costs time (for installation) and money.
The compositions and method of the invention overcome the difficulties associated with the prior art. In particular, we have found that certain of the compositions eliminate the need for a separate filter element.
SUMMARY OF THE INVENTION
A composition comprising a drying agent and a binder wherein: (a) said drying agent comprises an effective amount of a molecular sieve and said binder comprises an effective amount of a support comprising cellulose; (b) said drying agent comprises an effective amount of a molecular sieve and said binder comprises at least about 25 weight percent of a material selected from the group consisting of polyurethane foam and polyisocyanurate foam; or (c) said drying agent comprises an effective amount of a superabsorbent polymer and molecular sieve and said binder comprises an effective amount of a material selected from the group consisting of polyurethane foam, polyisocyanurate foam and a support comprising cellulose.
A process comprising contacting a chemical mixture comprising water with an effective amount of a composition comprising a drying agent and a binder wherein: (a) said drying agent comprises an effective amount of a molecular sieve and said binder comprises an effective amount of a support comprising cellulose; (b) said drying agent comprises an effective amount of a molecular sieve and said binder comprises at least about 25 weight percent of a material selected from the group consisting of polyurethane foam and polyisocyanurate foam; or (c) said drying agent comprises an effective amount of a superabsorbent polymer and molecular sieve and said binder comprises an effective amount of a material selected from the group consisting of polyurethane foam, polyisocyanurate foam and a support comprising cellulose
DETAILED DESCRIPTION OF THE INVENTION
A. The Desiccant Composition
The invention relates to a desiccant composition comprising a drying agent and a binder. Specifically, the invention relates to the following compositions: A composition comprising a drying agent and a binder wherein: (a) said drying agent comprises an effective amount of a molecular sieve and said binder comprises an effective amount of a support comprising cellulose; (b) said drying agent comprises an effective amount of a molecular sieve and said binder comprises at least about 25 weight percent of a material selected from the group consisting of polyurethane foam and polyisocyanurate foam; or (c) said drying agent comprises an effective amount of a superabsorbent polymer and molecular sieve and said binder comprises an effective amount of a material selected from the group consisting of polyurethane foam, polyisocyanurate foam and a support comprising cellulose.
In another embodiment, the drying agent comprises an effective amount of a molecular sieve and said binder comprises from about 30 to about 75 weight percent of a material selected from the group consisting of polyurethane foam and polyisocyanurate foam.
In yet another embodiment, the drying agent comprises about 50 weight percent of a molecular sieve and said binder comprises from about 50 weight percent of a material selected from the group consisting of polyurethane foam and polyisocyanurate foam.
1. Drying Agent
For purposes of this invention the following terms have the indicated meanings: “Polymer” means a homopolymer, copolymer (not limited to only two components), or mixtures thereof having a molecular weight of from about 1,000,000 to about 100,000,000 and preferably from about 10,000,000 to about 100,000,000 and more preferably from about 85,000,000 to about 100,000,00 and which are crosslinked sufficiently to impart moisture absorbing or adsorbing properties; “Superabsorbent Polymer” means a Synthetic or Semi-Synthetic (defined below) Polymer that swells, to at least twice its dry volume, with the addition of water at room temperature after standing for up to two hours; Semi-Synthetic means a derivative of a naturally occurring Polymer; and “Synthetic” means a Polymer produced through chemical reaction.
Exemplary Semi-Synthetic Polymers include, without limitation, cellulose ethers, modified starches, starch derivatives, natural gum derivatives, and mixtures thereof. Illustrative Synthetic Polymers include, without limitation, polymers, related polymers, and polymer salts of acrylamide, acrylic acid, ethylene oxide, methacrylic acid, polyethyleneimine, polyvinyl alcohol, polyvinyl pyrrolidone, and mixtures thereof. For purposes of this invention “related polymer” means that the polymer repeat unit, or a branch thereof, is extended by carbon atoms, preferably from one to four carbon atoms. For example, a related polymer of acrylic acid is one in which the vinyl group is extended by one carbon to form an allyl group.
Synthetic Polymers are preferred. Polyacrylic acid and its salts are more preferred and sodium polyacrylate (such as SXM70 and SXM77 from Stockhausen of Greensboro, N.C.) and potassium polyacrylate are most preferred.
Any molecular sieve may be used in the composition of the invention. These materials are commercially available from for example UOP of Des Plaines, Ill. and Grace Corporation of Baltimore, Md. They may also be prepared by methods well known in the art. Suitable molecular sieves include without limitation: Type A, Type B, Type L, Type X, Type Y and mixtures thereof. In the practice of this invention Type A is preferred. For refrigeration applications molecular sieves of 3-4 Angstroms are preferred such as XH6, XH7, XH9 and XH11 from UOP.
Multiple drying agents may be used in the compositions and method of the invention. Besides Superabsorbent Polymers and molecular sieves, other known drying agents can optionally be employed in the compositions of the invention. They include without limitation activated alumina, activated carbon, silica gel and mixtures thereof. When multiple drying agents are used they may be used in any ratio that is from about 1 to about 99 to 99 to about 1.
The selection of drying agent(s) including type and form will depend on the process (including materials and equipment) that produces the chemical mixture or in which the chemical mixture is being used. The shape and hardness of the drying agent should be chosen to withstand the rigors of the system in which it is used and to avoid entrainment in the equipment, plugging openings and conduits. The drying agent may be a powder, fine particles, fibers, or a shaped piece or pieces. We have found that a 50/50 mixture of superabsorbent polymer and molecular sieve (with 50 weight percent binder) provides superior capacity and drying ability th
Logsdon Peter Brian
Robinson Roy Philip
Thomas Raymond Hilton Percival
Williams David John
Anthony Joseph D.
Chase Deborah M.
Honeywell International , Inc.
Szuch Colleen D.
LandOfFree
Process for separating water from chemical mixtures does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for separating water from chemical mixtures, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for separating water from chemical mixtures will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3023194