Chemistry: analytical and immunological testing – Nuclear magnetic resonance – electron spin resonance or other...
Reexamination Certificate
2001-08-30
2004-05-25
Warden, Jill (Department: 1743)
Chemistry: analytical and immunological testing
Nuclear magnetic resonance, electron spin resonance or other...
C436S085000, C436S106000
Reexamination Certificate
active
06740528
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method for measuring the concentration of a stable free radical compound in a fluid in a process of treating a radical polymerizable compound containing the stable free radical compound.
BACKGROUND OF THE INVENTION
Radical polymerizable compounds such as ethylene, propylene, butadiene, acrylic acid, acrylates, methacrylic acid, methacrylates, acrylonitrile, methacrylonitrile, styrene, maleic acid and vinyl acetate, or mixtures containing two or more of them proceed in radical polymerization by the action of heat, peroxides, metal ions and the like to produce polymerized products, which adhere to distilling columns, reaction columns, heat exchangers such as reboilers, liquid transportation pipes, and the inner parts of apparatuses to result in serious operational obstacles such as a reduction in heat conductivity and clogging of the liquid transportation pipes. According to circumstances, it becomes necessary to interrupt the operation and remove the polymerized products, which sometimes causes consumption of huge cost and time.
For solving this problem, methods of inhibiting polymerization by addition of polymerization inhibitors have been used. As the polymerization inhibitors, there have been widely used aromatic amine compounds, hydroxylamine compounds, phenol compounds, quinone compounds and nitrous acid compounds. In recent years, however, attention has been focused on stable free radical compounds having steric hindrance groups represented by 2, 2, 6, 6-tetramethylpiperidine-1-oxyl because of their extremely high polymerization inhibition effect.
The polymerization inhibition of polymerizable unsaturated compounds by N-oxyl compounds has been disclosed in Japanese Patent 2818977 (corresponding to WO96/16921), JP-B-4-26639 (corresponding to WO87/04179), JP-A-10-1505, JP-A-10-158313, JP-A-10-182545, JP-A-10-182605, U.S. Pat. No. 5,880,230 and JP-A-11-222462 (The term “JP-A” as used herein means an “unexamined published Japanese patent application” and the term “JP-B” as used herein means an “examined Japanese patent publication”).
The stable free radical compounds scarcely react with each other because three-dimensionally large groups are adjacent to radicals in the stable free radical compounds, but can rapidly react with radicals from the radical polymerizable compounds to inhibit polymerization. The consumption of the radicals of the stable free radical compounds thus proceeds, so that the polymerization inhibition effect is lost in the state of insufficient concentration, resulting in the same state that no polymerization inhibitor is added. Industrially, from the viewpoint of safety operation, the stable free radical compounds are used in large amounts in many cases, and added exceeding a required amount, which raises an economical problem. A method has therefore been eagerly desired by which the concentration of the stable free radical compounds can be measured for a short period of time so that the compounds can be added depending on fluctuations in process conditions.
It has been disclosed in Bis [3-tert-butyl-5-(N-oxy-tert-butylamino)phenyl]Nitroxide in a Quartet Groud States; A Prototype for Persistent High-Spin Poly [(oxyimino)-1,3-phenylenes], T. Ishida, H. Iwamura (J. Am. Chem. Soc. 113, 4238-4241 (1991)), U.S. Pat. Nos. 5,780,257 and 5,811,305 that the stable free radical compound can be measured by means of electron spin resonance.
SUMMARY OF THE INVENTION
An object of the invention is to provide a method for measuring the concentration of a stable free radical compound quickly and with high precision.
As a result of intensive studies of methods for measuring the concentration of stable free radical compounds, the present inventors have found that electron spin resonance (hereinafter referred to as “ESR”) method is simplest and can determine the concentration with sufficient precision, and achieved the invention.
That is to say, a gist of the invention is a method for measuring a stable free radical compound by electron spin resonance method in a process of treating a radical polymerizable compound containing the stable free radical compound, and another gist of the invention is the method as described above, wherein the stable free radical compound is a 2, 2, 6, 6-tetramethylpiperidine-1-oxyl compound.
REFERENCES:
patent: 3966744 (1976-06-01), Goldstein et al.
patent: 5449724 (1995-09-01), Moffat et al.
patent: 5725839 (1998-03-01), Hsia
patent: 5780257 (1998-07-01), Aoyama et al.
patent: 5811305 (1998-09-01), Ono et al.
patent: 5880230 (1999-03-01), Syrinek et al.
patent: 6384267 (2002-05-01), Shingai et al.
Veregin et al. “Free Radical Polymerization for Narrow Polydispersity Resins: Electron Spin Resonance Studies of the Kinetics and Mechanism”, Macromolecules, 1993, v. 26, pp. 5316-5320.*
Veregin et al., “Mechanism of Living Free Radical Polymerizations with Narrow Polydispersity: Electron Spin Resonance and Kinetic Studies”, Macromolecules, 1995, 28(13), 4391-8.*
MacLeod et al. “Electron spin resonance studies of the stable free-radical polymerization of styrene”, Macromolecules, 1998, 31(2), 530-531.*
Chalfont we al., “A Probe for Homolytica Reactions in Solutins. II. The Polymerization of Styrene”, J. Am. Chem. Soc., 1968, 90 (25), pp. 7141-7142.
Kurumado Hiroshi
Onishi Norihiko
Yamaguchi Yoshiharu
Gakh Yelena G.
Hakuto Co., Ltd.
Sughrue & Mion, PLLC
Warden Jill
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