Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From carboxylic acid or derivative thereof
Reexamination Certificate
1999-07-15
2001-03-27
Hightower, P. Hampton (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From carboxylic acid or derivative thereof
C528S363000, C528S271000, C528S272000, C528S274000, C528S275000, C528S408000, C528S409000, C528S416000
Reexamination Certificate
active
06207793
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a process for the preparation of polytetramethylene-Ether-Glycol (PTMEG) Diesters by polymerization of tetrahydrofuran (THF) in the presence of a carboxylic anhydride by means of a catalyst, which is a acid-activated by the treatment of acid or ammonium chloride or sequential treatment with acid and ammonium chloride, and calcinated halloysite instead of bentonite, zeolite or kaolinite. The formula of the polymer is R—CO—O(CH
2
—CH
2
—CH
2
—CH
2
—O)n-COR
1
, in which R and R
1
are identical or different and are alkyl radicals.
BACKGROUND ART
The polymerization of THF by oxonium ion catalysis became known as the result of the basic work by H. Meerwein et al (Angew, Chemie 72, (1960), 972) and is described comprehensively in the monograph “Polytetrahydrofuran” by P. Dreyfuss, Gordon and Breach Sc. Publishers, New York, London, Paris 1982.
U.S. Pat. Nos. 3,433,829, 4,189,566 and 4,243,799 describe the polymerization of specially purified THF in the presence of a carboxylic anhydride and bleaching earth, which is a naturally occurring aluminum silicates having a cryptocrystalline three layer structure of the montmorillonite mineral. The mineral obtained from deposits exhibits physical and chemical properties which vary depending on the origin. In the international PCT-Application WO 94/05719 an improved process is described by catalysts selected from synthetic amorphous aluminum silicate, acid-activated and calcinated kaolin or zeolite in the presence of carboxylic anhydride. Similar procedures are described in the JP-Applications 4-306228, 4-277522 and the U.S. Pat. Nos. 5,208,385 and 5,210,283 with synthetic mainly amorphous silica-alumina. In particular, the activity of the catalyst is not constant, but instead varies from batch to batch. This is a serious disadvantage for commercial utilization of these catalysts. Besides, only very pure THF can be polymerized.
REFERENCES:
patent: 3433829 (1969-03-01), Durfelt
patent: 4189566 (1981-01-01), Mueller
patent: 4243799 (1980-02-01), Mueller
patent: 2760272 U (1977-10-01), None
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patent: 877269 (1961-09-01), None
patent: 4-306228 (1992-10-01), None
patent: 4-277522 (1992-10-01), None
patent: WO94/05719 (1994-03-01), None
patent: WO94/26803 (1994-11-01), None
H. Meerwein et al., “Die Polymerisation des Tetrahydrofurans”, Angeu. Chem. No. 24, Dec. 21, 1960, pp. 927-934.
Jurgen Falbe et al., “Rompp Chemie Lexikon”, Georg Thieme Verlag, p. 1713.
P. Dreyfuss, “Poly (Tetrahydrofuran)”, Gordon and Breach Science Publishers, 1982, pp. 1-69.
Hampton Hightower P.
Jacobson Price Holman & Stern PLLC
Korea PTG Co., Ltd.
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