Method of measuring concentration of polymerization inhibitor co

Details Method of measuring concentration of polymerization inhibitor co Method of measuring concentration of polymerization inhibitor co

1996-03-20

1997-07-29

Soderquist, Arlen

Chemistry: analytical and immunological testing

Hydrocarbon

Acyclic

436139, 436164, 436167, 436178, 570103, 570138, G01N 3344, C07C 1742, C07C 1700

Patent

active

056521472

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

The present invention relates to a quantitatively measuring method of a trace amount of a component contained in a fluorine-containing olefinic monomer gas. Particularly, the present invention relates to a method of measuring a concentration of a polymerization inhibitor (or a polymerization preventive agent), especially of a trace polymerization inhibitor, remaining in a fluorine-containing olefinic monomer after it has been separated from the polymerization inhibitor and purified.
In addition, the present invention also relates to a method of polymerizing a fluorine-containing olefinic monomer comprising a concentration measurement step of the polymerization inhibitor by such a measurement method.


BACKGROUND ART

Fluorine-containing olefinic monomers, in particular tetrafluoroethylene (which is hereinafter referred to as "TFE") and chloro-trifluoroethylene (which is hereinafter referred to as "CTFE") are industrially important chemicals as a starting material for the production of a polymer of such a single monomer or a copolymer of such a monomer with another monomer or as an intermediate product for the production of various chemicals. Since TFE and CTFE have so low boiling points as -76.3.degree. C. and -27.9.degree. C. respectively, they are usually stored under pressure. Because of their high reactivities, they are ready to polymerize even in the presence of a trace amount of oxygen. In order to prevent such polymerization of the monomer during its storage, it has been known that a polymerization inhibitor (polymerization preventive agent) is added to the monomer (see, for example, U.S. Pat. No. 2,407,405).
As such a polymerization inhibitor, terpene compounds such as dipentene, terpinolene, p-cymene, .alpha.-pinene, p-menthane and so on are concretely exemplified. Because of easy handling and commercial availability, a mixture of such terpene compounds is usually used. A composition of a terpene polymerization inhibitor mixture is shown in Table 1 below which is commercially available:


TABLE 1 ______________________________________ Component Product A Product B Product C ______________________________________ .alpha.-pinene 4.0% 5.0% 3.1% camphene 3.6 3.6 3.4 .beta.-pinene 1.3 0.2 0.5 .alpha.-terpinene 28.4 29.5 29.8 dipentene 14.6 11.4 18.5 .gamma.-terpinene 16.6 17.5 14.9 isoterpinolene 12.7 9.6 7.9 terpinolene 6.4 13.8 10.6 others 12.4 4.0 11.3 ______________________________________ Product A: Terpene mixture commercially available from ArakawaChemial as trade name of TerpeneB Product B: Terpene mixture commercially available from NipponTerpene as trade name of DipentenT Product C: Terpene mixture commercially available from YasuharaYushi as trade name of Dipenten
In order to use the stored monomer for a certain intended object such as polymerization thereof, it is required to remove the polymerization inhibitor of the terpenes which has been added to the monomer. For example, the monomer must be separated from the polymerization inhibitor and purified by treatment such as distillation, absorption or adsorption (for example, adsorption with silica gel). In such a case, if the separation of the polymerization inhibitor is insufficient or if a remaining amount of the polymerization inhibitor in the monomer fluctuates, the following disadvantages occur upon the polymerization of the monomer: consumption increase of a polymerization initiator, polymerization period increase due to reduction of polymerization reaction rate, decrease of polymer yield and property fluctuation of produced polymer. Therefore, the monomer is used as, for example, a polymerization starting material after the polymerization inhibitor has been removed from the monomer by a multistage separation-purification.
For the production of a polymer from a single kind monomer or a copolymer comprising the monomer, it is firstly desired to make a monomer quality uniform from a viewpoint of polymerization stability while polymerization conditions (in particular, a pressure and a temperature

REFERENCES:
patent: 2407405 (1946-02-01), Dietrich
patent: 3695847 (1972-10-01), Hirschfeld
J.G. Kirchner et al. Anal. Chem. 1951, 23, 420-425.
A.A. Belyakov Chem. Abstr. 1961, 55, 24396d.
Y. Watanabe Chem. Abstr. 1963, 58, 11405e.
M.G. Manson et al. J. Chem. Phys. 1973, 59, 1092-1098.

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