Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Polymers from only ethylenic monomers or processes of...
Reexamination Certificate
2000-04-15
2001-10-09
Teskin, Fred (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Polymers from only ethylenic monomers or processes of...
C526S290000, C528S501000
Reexamination Certificate
active
06300444
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a process for producing butene polymer having high reactivity and being low in organic fluorine content, using boron trifluoride complex catalyst. More particularly, the invention relates to an inexpensive process for producing butene polymer containing 80 mol % or more of molecules having highly reactive terminal vinylidene structure and of low organic fluorine content, by means of liquid-phase polymerization of hydro-carbons containing isobutene.
BACKGROUND ART
It is disclosed in U.S. Pat. No. 4,152,499 that polymer obtained by polymerizing pure isobutene using boron trifluoride complex catalyst, is butene polymer containing double bonds of vinylidene structure in a high ratio and that maleic modification using maleic anhydride or the like can proceed efficiently. The maleic-modified polybutene disclosed in this patent gazette is accepted as being preferable in view of its performance, economy and environmental protection as compared with the conventional maleic-modified polybutene that has been obtained through chlorination process.
Accordingly, in recent years, there have been made many a proposal for producing polybutene having a large content of vinylidene-type double bonds, using boron trifluoride complex catalyst. Such butene polymer has excellent reactivity to maleic anhydride, in addition, it has also excellent adaptability to epoxidation or the like.
It is more advantageous in view of economy to use butadiene raffinate obtained from large-scale production rather than the use of 100% pure isobutene as a starting material in order to obtain polybutene having larger content of vinylidene-type double bonds. However, the use of butadiene raffinate as a starting material is not acceptable in that the amount of remained fluorine in polymer (hereinafter referred to as “residual organic fluorine”) that is prepared in the presence of boron trifluoride catalyst, is large. As this residual fluorine is organic fluorine, if the butene polymer of this type is used as an additive to fuel oil, fluorine compounds are produced during the combustion of the fuel oil and fluorine compounds are released into the air to cause possibly air pollution.
Specifically, in the polymerization using boron trifluoride-methanol complex catalyst, when pure isobutene is used as a starting material, residual fluorine content is as low as 5 ppm or less, meanwhile if butadiene raffinate is used as a starting material, residual fluorine content is generally as high as 60 ppm or more, which is usually 90 to 120 ppm.
In view of air pollution, because polymer containing such a high content of residual fluorine as mentioned-above is not preferable, polymer of low fluorine content is demanded.
In U.S. Pat. No. 5,674,955; there is disclosed a method for reducing the content of residual organic fluorine to a level lower than 40 ppm by subjecting raw material of butene mixture to polymerization after reducing 20% or more of 1-butene content through catalytic hydroisomerisation. According to the disclosure on examples, however, even when 1-butene content in feed material is reduced from 22% to 5% by weight, the organic fluorine content in polymers is barely reduced to 17 ppm. Furthermore, this method necessitates one additional process in order to reduce the content of 1-butene as pretreatment of starting material.
PCT Publication WO 96140808 discloses a method for reducing organic fluorine content by dividing polymerization process into plurality of steps. However, this proposal is also economically unfavorable in view of costs for both equipment and operation because this also necessitates additional processes likewise the above-mentioned method.
It is an object of the present invention to provide an efficient process for preparing butene polymer having high reactivity in maleic-modification and epoxidation and the content of residual fluorine being reduced to an acceptable level for practical use without accompanying substantial increases in investment in equipment and also in additional cost for starting material.
DISCLOSURE OF INVENTION
Accordingly, a first aspect of the present invention relates to a process for preparing butene polymer which contains 80 mol % or more of polymer molecules having terminal vinylidene structure and less content of residual organic fluorine, which process comprises the following Steps (I) and (II):
Step (I): to carry out polymerization in a liquid phase at a temperature of −100° C. to +50° C. with a residence time of 5 minutes to 4 hours by introducing a starting material of a C
4
fraction comprising butene-1, butene-2, isobutene and butanes into a polymerization zone, in which complex catalyst composed of boron trifluoride, ether and alcohol and/or water is in a ratio of 0.05 to 500 mmol in terms of boron trifluoride relative to 1 mol of olefin components in the above starting material; and
Step (II): to reduce by distillation trimer or lighter components contained in polymer obtained in Step (I) to 0.2% by weight or less.
A second aspect of the present invention relates to a process for preparing butene polymer as described in the first aspect of the invention, wherein the starting material is C
4
fraction comprising 10 to 40% by weight of butene- 1, 1 to 40% by weight of butene-2, 35 to 70% by weight of isobutene, 10 to 30% by weight of butanes and 0.5% by weight or less of butadiene. A third aspect of the present invention relates to a process for preparing butene polymer as described in the first aspect of the invention, wherein the complex catalyst comprises boron trifluoride, ether, and alcohol and/or water in the molar ratio as defined by the following Equation (1), wherein the symbol x is a numeral in the range of 0.005 or more but less than 0.3, thereby reducing residual organic fluorine content to 30 ppm or less in terms of fluorine atom.
(boron trifluoride)
0.5-1.1
: (ether)
1−X
: (alcohol and/or water)
X
Equation (1)
A fourth aspect of the present invention relates to a process for preparing butene polymer as described in the first aspect of the invention, wherein the ether comprises aliphatic ethers having 2 to 16 carbon atoms.
A fifth aspect of the present invention relates to a process for preparing butene polymer as described in the first or fourth aspect of the invention, wherein the ether comprises dialkyl ethers (two alkyl groups can be the same or different), the number of carbon atoms of each alkyl group is 1 to 8 and each carbon atom bound to oxygen atom is primary carbon atom.
A sixth aspect of the present invention relates to a process for preparing butene polymer as described in the first aspect of the invention, wherein the alcohol comprises linear or branched chain aliphatic alcohols having 1 to 21 of carbon atoms.
A seventh aspect of the present invention relates to a process for preparing butene polymer as described in the first aspect of the invention, wherein the conversion of isobutene in the Step (I) is in the range of 60 to 100%.
A eighth aspect of the present invention relates to a process for preparing butene polymer as described in the first aspect of the invention, wherein complex catalyst composed of boron trifluoride, ether, and alcohol and/or water is introduced into a polymerization zone with a ratio of 0.05 to 10 mmol in terms of boron trifluoride with respect to 1 mol of olefin components of starting material in the Step (I).
A ninth aspect of the present invention relates to a process for preparing butene polymer as described in the first aspect of the invention, wherein the number average molecular weight of butene polymer is in the range of 500 to 15,000.
A tenth aspect of the present invention relates to a process for preparing butene polymer as described in the first aspect of the invention, wherein the complex catalyst comprises boron trifluoride, ether, and alcohol and/or water in the molar ratio as defined by the following Equation (II) in which the numeral x is in the range of 0.005 or more but less than 0.1, thereby reducing the content of residu
Ohashi Koichi
Okada Toshio
Takashima Tsutomu
Tokumoto Yuichi
Hollander Law Firm, P.L.C.
Nippon Petrochemicals Company Limited
Teskin Fred
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