Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From heterocyclic reactant containing as ring atoms oxygen,...
Reexamination Certificate
1999-11-09
2002-03-19
Lovering, Richard D. (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From heterocyclic reactant containing as ring atoms oxygen,...
C502S080000, C502S083000, C525S409000, C528S413000, C528S416000, C568S617000, C568S679000
Reexamination Certificate
active
06359108
ABSTRACT:
The present invention relates to a process for polymerizing cyclic ethers over a heterogeneous catalyst comprising one or more pillared interlayered clays (PILCs).
Polytetrahydrofuran (PTHF), also known as poly(oxybutylene glycol), is an intermediate for the preparation of polyurethane, polyester and polyamide elastomers, where it is used as diol component. The incorporation of PTHF renders these polymers soft and flexible, which is why PTHF is also known as a soft segment component for these polymers. Polytetrahydrofuran monoesters of monocarboxylic acids are used, for example, as plasticizers (U.S. Pat. No. 4,482,411), impregnating agents, monomers (EP-A 286 454), emulsifiers and dispersants, and are also employed for deinking in the recycling of waste paper.
The cationic polymerization of tetrahydrofuran (THF) using catalysts has been described by Meerwein et al. (Meerwein et al. (1960) Angew. Chem. 72, 927). The catalysts used either are preshaped catalysts or are formed in situ in the reaction mixture. In the latter case, oxonium ions which initiate the THF polymerization are generated in the reaction mixture using strong Lewis acids such as boron trichloride, aluminum trichloride, tin tetrachloride, antimony pentachloride, ferric chloride or phosphorus pentafluoride or strong Bronsted acids such as perchloric acid, tetrafluoroboric acid, fluorosulfonic acid, chlorosulfonic acid, hexachlorostannic acid, iodic acid, hexachloroantimonic acid or tetrachloroferric acid, and using reactive compounds called promoters such as alkylene oxides, eg. ethylene oxide, propylene oxide, epichlorohydrin or butylene oxide, oxetanes, orthoesters, acetals, &agr;-halo ethers, benzyl halides, triarylmethyl halides, acid chlorides, &bgr;-lactones, carboxylic anhydrides, thionyl chloride, phosphorus oxychloride or sulfonic acid halides. However, only a few of the multiplicity of catalyst systems have gained industrial importance since some of them are highly corrosive and/or in the course of PTHF preparation give rise to colored products of limited utility. Moreover, many of these catalyst systems are not true catalysts but must be employed in stoichiometric amounts relative to the macromolecule to be prepared and are consumed in the course of the polymerization. The preparation of PTHF using fluorosulfonic acid as catalyst according to U.S. Pat. No. 3,358,042, for instance, requires the use of about two molecules of fluorosulfonic acid for each molecule of PTHF. The use of halogen-containing catalysts has the particular disadvantage that halogenated byproducts are formed in PTHF polymerization which are difficult to remove from pure PTHF and adversely affect the properties thereof.
In the preparation of PTHF in the presence of the abovementioned promoters, these promoters are incorporated into the PTHF molecule as telogens so that the primary product of THF polymerization is not PTHF but a PTHF derivative, for example a PTHF diester or disulfonate from which PTHF has to be liberated in a further reaction, for example by saponification or transesterification (cf. U.S. Pat. No. 2,499,725 and DEA 2 760 272). Telogens are generally compounds which cause chain termination and/or chain transfer in the polymerization. If alkylene oxides are used as promoters, these also act as comonomers and are incorporated into the polymer which leads to the formation of THF-alkylene oxide copolymers which have different application properties than PTHF.
PTHF may be prepared in one step by polymerizing THF in the presence of water, 1,4-butanediol or low molecular weight PTHF oligomers. If 2-butyne-1,4-diol is used as telogen, copolymers of THF and 2-butyne-1,4-diol are produced which, however, may be converted into PTHF by hydrogenating the triple bonds contained therein.
U.S. Pat. No. 5,149,862 discloses the use of sulfate doped zirconium dioxide as acidic heterogeneous polymerization catalyst which is insoluble in the reaction medium. A mixture of acetic acid and acetic anhydride is added to the reaction medium to accelerate the reaction, since the polymerization is very slow without these promoters and conversion over 19 hours is only 6%. This process gives rise to PTHF diacetates which have to be converted into PTHF subsequently by saponification or transesterification.
PTHF diesters are likewise formed in the polymerization of THF using bleaching earth catalysts, as described in EP-A 0 003 112.
U.S. Pat. No. 4,303,782 uses zeolites for the preparation of PTHF. The THF polymers obtainable by this process have very high average molecular weights (M
n
=250.000-500.000 D) and have not found general acceptance for the above-mentioned applications. The process has therefore likewise attained no industrial importance.
DE 4 433 606 describes for example the preparation of PTHF in one step by polymerizing THF over heterogeneous supported catalysts which comprise a catalytically active amount of an oxygen-containing molybdenum and/or tungsten compound on an oxidic support material and which have been calcined at from 500 to 1000° C. after application of the precursor compounds of the oxygen-containing molybdenum and/or tungsten compounds onto the support material precursor. These catalysts have the disadvantage that expensive zirconium dioxide is used as support material.
It is an object of the present invention to provide a process which enables the polymerization of cyclic ethers to be performed in an advantageous manner, especially with high space-time yields, and without the disadvantages described above.
We have found that this object is achieved by a process for polymerizing cyclic ethers over a heterogeneous catalyst comprising one or more pillared interlayered clays (PILCs), which are known from Figueras, F., Catal. Rev. Sci Eng. 30(3) (1988), 457 or Jones, Catal. Today 2 (1988) 357, for example.
PILCs are generally layer structures intercalated with one or more metal compounds in the form of pillars (cf., for example, FIG. 2 in Figueras, F. (1988), supra). The interlayer distance is generally from about 4 to 80 Å, preferably from about 8 to 30 Å, especially from about 8-25 Å. The space which is opened up between the layer structures by the intercalated metal compounds is available as pore volume for the reactants of the polymerization of the invention. Additional pore volume is created, for example, by delamination, ie. “house of cards” structures are formed.
Preferred metal compounds for the pillars include oxides and/or sulfides of elements of main groups III and IV of the Periodic Table of the Elements, in particular of aluminum, gallium, indium, thallium, silicon, germanium, tin or lead, especially aluminum, gallium or silicon, or of elements of the transition groups, preferably of titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten, manganese or iron, especially of titanium, zircomium, vanadium, tantalum, chromium or iron, which may be present as mixtures with one another or as mixtures with other oxides and/or sulfides, eg. of magnesium, boron, cobalt or nickel. Oxidic pillars are preferred.
Examples of useful metal oxides include Al
2
O
3
, ZrO
2
, TiO
2
, Cr
2
O
3
, Ga
2
O
3
, SiO
2
, Ta
2
O
5
, Fe
2
O
3
, and V
2
O
5
. Examples of other oxides that may be present include MgO, B
2
O
3
, Co
2
O
3
or NiO. A mixture of Al
2
O
3
and MgO which results in a mixed aluminum/magnesium oxide is especially preferred. Examples of sulfides include Fe
2
S
3
.
Metal compounds having perovskite structure, for example LaCoO
3
, LaNiO
3
, LaMnO
3
and/or LaCuO
3
, are also suitable as pillars (cf. WO 92/00808, for example).
The amount of intercalated metal is preferably about 1-50% by weight, in particular 2-35% by weight, based on the finished PILC and calculated as % by weight of metal.
Layer compounds suitable for preparing PILCs are preferably sheet silicates, especially clays. Examples of clay minerals include smectite minerals such as montmorillonite in pure form or as bentonite constituent. Other examples of smectites are beidellite, hectorite, nont
Becker Rainer
Eller Karsten
Fischer Rolf
Möller Ulrich
Plitzko Klaus-Dieter
BASF - Aktiengesellschaft
Keil & Weinkauf
Lovering Richard D.
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