Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Plural component system comprising a - group i to iv metal...
Reexamination Certificate
2001-11-27
2003-04-01
Cooney, Jr., John M. (Department: 1711)
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Plural component system comprising a - group i to iv metal...
C502S126000, C502S127000, C502S172000, C502S349000, C502S350000, C521S123000, C521S124000, C521S170000, C521S172000, C521S173000, C528S279000
Reexamination Certificate
active
06541411
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention provides new types of titanium/zirconium catalysts, a process for preparing these catalyst, and their use in esterification reactions, transesterification reactions and polycondensation reactions to prepare esters or polyesters.
Polyesters are important industrial polymers which have been used for some time now, for example, to produce fibers or as polyol components in polyurethane systems (see G. Oertel in Polyurethane Handbook, Hanser Publishers (1994), p. 65-72). Polyesters are prepared either by direct esterification of low molecular weight polycarboxylic acids (e.g. adipic acid) with low molecular weight polyalcohols (e.g. diethylene glycol) or by transesterification starting from alkyl esters of polycarboxylic acids and polyalcohols. A catalyst is generally used in either of the reactions mentioned above in order to shorten the reactor occupation times and to build up high molecular weights (see R. E. Wilfong in Journal of Polymer Science, vol. 54 (1961), p. 385-410 and A. Fradet, E. Maréchal in Advances in Polymer Science 43, Springer Verlag (1982), p. 51-142). Many commercial processes use, for example, manganese, zinc, antimony or tin salts as catalysts for esterification, transesterification or polycondensation reactions. However, the problem with some of the metal compounds mentioned above is the tendency to form insoluble complexes which can cause problems during further processing of the esters or polyesters. In addition, the physiological unacceptability and potentially harmful effects in the environment of the classes of compounds mentioned above are increasingly acting against their use as catalysts.
Organic titanium compounds, in particular titanium orthoesters such as, for example titanium tetraisopropylate and titanium tetra-n-butylate, are also effective and frequently used esterification, transesterification and polycondensation catalysts. See, for example, U.S. Pat. No. 2,822,348. General use of these titanium catalysts, however, is restricted due to a number of disadvantages. Thus, organic titanium compounds can be insoluble in the reaction mixture (e.g. poly(titanium alkylate)), which leads to uneven distribution of the catalyst and has an effect on its activity. Furthermore, certain titanium catalysts are hydrolysis-sensitive which impairs the storage-stability of the catalyst systems. In addition, polymeric titanium compounds may be produced during the course of reaction, which ultimately results in a cloudy reaction product which can be purified only by means of a costly filtration procedure. In addition, titanium compounds normally react with traces of impurities such as, for example, aldehydes, which are also produced during the esterification, transesterification or polycondensation reaction and in this way produce unwanted yellow coloration in the reaction product. It has been shown that such unwanted discoloration can be counteracted by the use of multi-component catalyst systems. Thus, for example, U.S. Pat. No. 6,080,834 describes a catalyst system consisting of a titanium compound, a complexing reagent (e.g. a hydroxycarboxylic acid), a phosphorus compound and, optionally, other additives in a solvent. The use of catalyst systems consisting of titanium orthoesters, alcohols (e.g. ethylene glycol), 2-hydroxycarboxylic acids and bases (e.g. sodium hydroxide) is described in, for example, U.S. Pat. No. 5,866,710. The preparation of such complicated catalyst systems is obviously costly and therefore has a large economic impact when used in esterification, transesterification and polycondensation reactions. In addition, there is the risk that further processing of the esters or polyesters in various applications (e.g. polyurethane systems) may be impaired by the presence of the additives mentioned above in the catalyst systems.
For the reasons discussed above, there is a need for new types of catalysts which are characterized by the simplest possible composition, high activity in esterification, transesterification and/or polycondensation reactions, adequate solubility in the starting components and in the end product, and good resistance to hydrolysis, and which are physiologically acceptable. It is also desirable that catalysts according to the invention lead to a reaction product with improved optical properties (e.g. less unwanted color in the polyester).
Surprisingly, it has now been found that when using suitable starting materials new types of catalysts can be prepared which, in comparison to the catalysts described above, are characterized by a simpler, and thus, more economically viable composition and which exhibit good resistance to hydrolysis. In addition, catalysts according to the invention provide a reaction product with improved optical properties, i.e. less unwanted color in the esters or polyesters. Other advantages of catalysts according to the invention (e.g. high activity, good solubility in the starting components and in the end product, physiological acceptability) are also obtained.
SUMMARY OF THE INVENTION
The present invention thus provides titanium and/or zirconium catalysts comprising the reaction product of:
a) one or more orthoesters or one or more condensed orthoesters of titanium and/or zirconium; with
b) one or more polyalcohols which contain at least two hydroxyl groups and have a number average molecular weight of at least 180 g/mol;
wherein the molar ratio of polyalcohol b) to orthoester or condensed orthoester of titanium and/or zirconium a) is at least 2:1.
Orthoesters or condensed orthoesters of titanium or zirconium a) are used to prepare catalysts according to the invention. In a preferred embodiment, the orthoesters correspond to the general formula:
M(OR)
4
,
wherein:
M: represents titanium or zirconium, and
each R: may be the same or different, and individually represents a linear alkyl group, a branched alkyl group or a cyclic alkyl group.
Suitable alkyl groups R in the general formula above preferably contain from 1 to 6 carbon atoms.
Particularly preferred orthoesters are titanium tetraisopropoxylate and titanium tetra-n-butoxylate.
Condensed orthoesters for the preparation of the catalysts of the invention are typically obtained by careful, partial hydrolysis of the titanium/zirconium orthoester and, inter alia but not exclusively, are represented by the general formula:
R
1
O[M(OR
1
)
2
O]
n
R
1
,
wherein:
M: represents titanium or zirconium; and
each R
1
: may be the same or different, and individually represents a linear alkyl group, a branched alkyl group or a cyclic alkyl group;
n: represents a number less than 20, and preferably a number less than 10.
In the formula above, the group R
1
preferably contains 1 to 6 carbon atoms.
Particularly preferred condensed orthoesters are poly(titanium isopropoxylate) and poly(titanium butoxylate).
The process for the preparation of the titanium and/or zirconium catalysts of the present invention comprises reacting
a) one or more orthoesters or one or more condensed orthoesters, with
b) one or more polyalcohols. Suitable polyalcohols for the present invention include those polyalcohols which contain at least two hydroxyl groups and have a number average molecular weight of at least 180 g/mol, in particularly preferred are those polyalcohols with two to six hydroxyl groups and a molecular weight of 180 g/mol to 4500 g/mol.
In a preferred embodiment, polyalcohols b) are polyetherpolyols. Polyetherpolyols used according to the invention may be prepared, for example, by polyaddition of alkylene oxides to polyfunctional starter compounds in the presence of caesium, rubidium, strontium or barium hydroxide or alternative basic catalysts. Polyetherpolyols used according to the invention are preferably prepared using a highly active double metal cyanide catalyst from a starter compound with on average 2 to 8, preferably 2 to 6, active hydrogen atoms and one or more alkylene oxides, as is described, for example, in U.S. Pat. No. 5,545,601 (believed to correspond to EP-A 761,708), the disclosure of which is herein
Bauer Erika
Hoffmann Andreas
Nefzger Hartmut
Bayer Aktiengesellschaft
Brown N. Denise
Cooney Jr. John M.
Gil Joseph C.
LandOfFree
Titanium/zirconium catalysts and their use to prepare esters... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Titanium/zirconium catalysts and their use to prepare esters..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Titanium/zirconium catalysts and their use to prepare esters... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3103476