Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Process of treating scrap or waste product containing solid...
Reexamination Certificate
2001-02-28
2004-06-15
Cain, Edward J. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Process of treating scrap or waste product containing solid...
C521S040000, C521S048000, C521S048500, C521S049500
Reexamination Certificate
active
06750260
ABSTRACT:
FIELD OF THE INVENTION
This invention relates in general to chemical recycling processes, and in particular to a process for the chemical recycling of polyurethane-containing scrap, such as light fraction separated from automotive shredder residue (hereinafter referred to as “light ASR”) or flexible foam separated from automotive shredder residue. The invention also relates to novel polyol products, produced by the process, for preparing polyurethanes.
BACKGROUND INFORMATION
It is well known in the art that chemolysis processes such as glycolysis, hydrolysis, and aminolysis can be used for depolymerization and recycling of polyurethane scrap, as well as condensation polymers such as polyesters (e.g., PET), polyamides (e.g., nylons), and polyureas (e.g., RIM, RRIM, SRIM). Major differences between glycolysis, hydrolysis, and aminolysis are in the type of reactant utilized for depolymerization and the composition of final products. In the case of hydrolysis, water is utilized for decrosslinking of the polymer, requiring a relatively high reaction pressure and temperature. The hydrolysis of polyurethanes is usually carried out at temperatures higher than 200° C. and pressures higher than 16 bars (230 psi). The hydrolysis products are original polyols and amines (isocyanate derivatives). Glycolysis can be carried out at atmospheric pressure at about 200° C. (between 180° and 240° C.). Gycolysis products are original polyols, isocyanate-containing polyols, and residual glycolytic agents (reactants). Aminolysis can be carried out at atmospheric pressure and temperature much lower than that required for glycolysis. Aminolysis products are disubstituted ureas and original polyols.
Representative of the chemolysis technology are U.S. Pat. Nos. 2,937,151; 3,300,417; 3,404,103; 3,632,530; 3,708,440; 3,738,946; 3,983,087; 4,044,046; 4,110,266; 4,159,972; 4,316,992; 5,300,530; 5,357,006; 5,556,889; 5,635,542; and 6,020,386. A recent review of chemolysis processes, and more specifically glycolysis, has been published by Rasshofer, W. and Weigand, E. [“Automotive Polyurethanes—Advances in Plastics Recycling,” Volume 2, (2001), Technomic Publishing Co., Inc., Lancaster, Pa. 17604, USA, pp.66-129].
Most of the chemolysis products are described to be used in polyurethanes without any modification or with a minimum modification. Practically all chemolysis processes including glycolysis result in amine formation which greatly affects the reactivity of the chemolysis products with isocyanates. U.S. Pat. No. 6,020,386 describes addition of a dialkyl carbonate and/or 1,3-dicarbonyl compound to the resultant alcoholysis product. U.S. Pat. No. 5,635,542 describes addition of 1,3-dicarbonyl compound to the polyurea and/or polyurethane polyurea reaction mixture before or during the reaction. U.S. Pat. No. 5,556,889 describes addition of at least one epoxidized native fatty oil to the reaction mixture after glycolysis. U.S. Pat. No. 5,357,006 describes a process for the preparation of recyclate polyols obtained by glycolysis of polyurethanes and/or polyurea-polyurethanes by addition of monofunctional and/or difunctional glycidyl ethers over the entire course of the reaction. U.S. Pat. No. 5,300,530 describes a process in which an alkylene oxide (propylene oxide) is added to the glycolysis polyol products in a molar ratio of <1 mole of alkylene oxide per mole of active amine hydrogen atom in the glycolysis polyol products. U.S. Pat. No. 4,110,266 discloses a process for decomposing polyurethane using glycols, polyols, amines, and/or ammonia and converting the decomposition mixture into a product substantially free of primary and secondary amines and containing an increased amount of polyols by reacting the decomposition mixture with an excess of alkylene oxide with respect to active hydrogen atoms of the amines for a period sufficient to convert the amines to polyols and forming a product mixture substantially free of primary and secondary amines. It is preferred that more than one and up to 3 moles of alkylene oxide is employed per mole of active hydrogen atom of the amines. Regardless of all these modifications, the final chemolysis products have extremely broad molecular weight distributions and only a limited amount can be used in a mixture with virgin polyols to prepare polyurethanes with useful properties.
U.S. Pat. No. 5,274,004 to van der Wal discloses a process for converting a polyurethane polymer to polyol, and the use of the polyol to prepare a fresh polyurethane polymer. The process is limited to the use of polyether-based polyurethanes. There is no suggestion to use a mixture of polyurethanes and other materials such as are found in light ASR. The process is also limited to an alkanolamine (more specifically diethanolamine) as a chemolysis liquid reactant. The process requires the reaction of the polyurethane with a liquid mixture of an alkanolamine and a metal hydroxide to create an intermediate product. The intermediate product is treated with an alkylene oxide to produce polyol.
Another challenge for recycling in general and especially polyurethanes is obtaining a sustainable amount of the scrap and a sustainable quality of the scrap. In the case of the post-consumer scrap, there are several challenges including collection and storage, transportation of usually light materials to long destinations, classification and characterization of materials without any control of their history during their service life and their history as scrap. Scrap may be contaminated with other organic and inorganic materials including some potentially hazardous materials. This may explain why only a limited amount and mostly post-industrial polyurethane scrap materials have been recycled so far utilizing chemolysis processes [Rasshofer, W. and Weigand, E., “Automotive Polyurethanes—Advances in Plastics Recycling,” Volume 2, (2001), Technomic Publishing Co., Inc., Lancaster, Pa. 17604, USA, pp.66-129].
The “light ASR” is one of the automotive shredder residue (ASR) streams routinely generated in most downstream automotive shredder processes. Over 3 million tons of ASR has been generated per year by over 200 automotive shredders in the U.S. and Canada [Recycling Today, July 1995, p.60]. ASR contains approximately 25% light ASR [SAE Technical Paper Series 1999-01-0670]. The compositions of ASR streams are relatively consistent and the composition of the specific light ASR depends mostly on the type of shredding process (“dry,” “wet,” “damp”), the particle size of shredded material, and the type of the downstream separation process (flotation, rotating trommel or a multiple level vibratory screen) [SAE Technical Paper Series 1999-01-0670]. There are many relatively simple processes that may be utilized to upgrade urethane content in these streams and eliminate contaminants such as heavy metals. Simple size reduction by secondary shredding and washing with industrial detergents significantly affects the percent of combustibles in the light ASR. There are reported processes specifically designed to separate flexible foams from ASR such as U.S. Pat. No. 5,443,157 that describes a system for separation and cleaning of a polyurethane foam from ASR.
SUMMARY OF THE INVENTION
The present invention relates to a process of chemically recycling polyurethane-containing scrap. In a first step of the process, polyurethane-containing scrap is subjected to a chemolysis reaction to produce chemolysis polyol products. In a second step of the process, the chemolysis polyol products are used as initiators in a reaction with alkylene oxide to produce oxyalkylated polyols for preparing polyurethanes.
REFERENCES:
patent: 2937151 (1960-05-01), Broeck
patent: 3300417 (1967-01-01), McElroy
patent: 3404103 (1968-10-01), Matsudaira et al.
patent: 3632530 (1972-01-01), Kinoshita
patent: 3708440 (1973-01-01), Frulla et al.
patent: 3738946 (1973-06-01), Frulla et al.
patent: 3983087 (1976-09-01), Tucker et al.
patent: 4044046 (1977-08-01), Kondo et al.
patent: 4110266 (1978-08-01), Sheratt
Brooks & Kushman P.C.
Cain Edward J.
Troy Polymers, Inc.
LandOfFree
Process for chemical recycling of polyurethane-containing scrap 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 chemical recycling of polyurethane-containing scrap, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for chemical recycling of polyurethane-containing scrap will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3360228