Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From reactant having at least one -n=c=x group as well as...
Reexamination Certificate
2001-10-25
2003-05-27
Gorr, Rachel (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From reactant having at least one -n=c=x group as well as...
C528S076000, C528S414000, C528S415000, C528S416000, C528S421000, C568S620000, C252S182270
Reexamination Certificate
active
06569981
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to crystallising polyether polyols, to a method of producing them, and to the use thereof for the production of polyurethane materials, particularly polyurethane foams, polyurethane elastomers and polyurethane coatings.
SUMMARY OF THE INVENTION
Crystallising polyether polyols, particularly poly(oxypropylene) polyols, are known and are distinguished in polyurethane (PUR) applications by an improvement in the mechanical properties of the product. One significant disadvantage of their use in PUR formulations is the high viscosity of these polyols, even in their molten state at temperatures from 60 to 100° C., which often makes it necessary to conduct reactions in solvents. The production and purification of crystallising polyether polyols is also made considerably more difficult due to their high viscosity. The high viscosity of these products is substantially caused by polymer constituents which have a particularly high molecular weight.
The object of the present invention was therefore to provide crystallising polyether polyols with a reduced viscosity, in order to avoid the aforementioned disadvantages during processing.
The object of the present invention has been achieved by the provision of new crystallising polyether polyols.
The present invention therefore relates to crystallising polyether polyols which can be produced firstly by the reaction of propylene oxide and polyhydroxy compounds in the presence of an alkoxy compound which contains zinc and/or aluminium atoms to form a crystallising polyether polyol with an average molecular weight M
n
from 500 to 5000, followed by the further reaction of the crystallising polyether polyol which is thus obtained with 10 to 90% by weight, with respect to the amount of crystallising polyol, of an epoxide in the presence of a catalyst, to form a crystallising polyether polyol with an average molecular weight M
n
from 1000 to 20,000.
The present invention further relates to a method of producing crystallising polyether polyols, which is characterised in that propylene oxide and polyhydroxy compounds are first caused to react in the presence of an alkoxy compound which contains zinc and/or aluminium atoms to form a crystallising polyether polyol with an average molecular weight M
n
from 500 to 5000, and the crystallising polyether polyol which is thus obtained is subsequently caused to react further with 10 to 90% by weight, with respect to the amount of crystallising polyol, of an epoxide in the presence of a catalyst which does not polymerise propylene oxide stereospecifically, to form a crystallising polyether polyol with an average molecular weight M
n
from 1000 to 20,000.
According to the invention, the reaction with the epoxide of the crystallising polyether polyol which is obtained as an intermediate can be effected catalytically in any desired manner, for example by acidic, basic or coordinative catalysis, preferably by alkali metal cyanide or double metal cyanide (DMC) catalysis.
Reference is made in this connection to the fact that the crystallising polyether polyol which is obtained as an intermediate can be further processed with the epoxide in the manner described, without the separation of the catalyst used in the production of said polyether polyol.
Polyhydroxy compounds which are suitable according to the invention include all the polyhydroxy compounds which are known for reaction with epoxides, particularly polyhydroxy compounds which comprise 2 to 6 hydroxyl groups per molecule and which have a molecular weight from 90 to 2000, preferably from 200 to 1500. Polyhydroxy compounds which are used in particular are polypropylene glycols, polyethylene glycols, dihydroxypolyethylene oxide-polypropylene oxide block copolymers and randomly structured EO/PO copolymers. Compounds of this type are described in Kirk-Othmer (3) 1, 754 to 789 for example.
The following are cited as preferred polyhydroxy compounds: polypropylene glycols with an average molecular weight M
n
from 200 to 2000 which are initiated on ethylene glycol, diethylene glycol, dipropylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, glycerol, trimethylolpropane, pentaerythritol, sorbitol or saccharose, or copolymers of propylene oxide and ethylene oxide which have an average molecular weight M
n
from 200 to 2000 and which are initiated on ethylene glycol, propylene glycol, 1,4-butanediol, glycerol or trimethylolpropane, as well as mixtures of said polyhydroxy compounds with each other.
Catalysts which are capable of polymerising propylene oxide stereospecifically are used for the production of the crystallising polyether polyols (intermediates). These catalysts are known alkoxy compounds which contain aluminium and/or zinc atoms and which also optionally contain aluminium- and/or zinc alkyl groups, such as those which are described in the Encycl. of Polym. Sci. and Engineering 6, 284-307, for example.
The catalysts which are preferably used for stereospecific polymerisation are bimetallic &mgr;-oxoalkoxides which contain aluminium and/or zinc atoms, such as those which are described in U.S. Pat. No. 3,432,445. The bimetallic &mgr;-oxoalkoxides which contain aluminium and/or zinc atoms and which are used in particular are those which are termed Teyssie catalysts and which correspond to the general formula given below:
wherein
R represents a C
2
-C
12
alkyl radical.
Examples of suitable alkyl radicals include: ethyl, propyl, isopropyl, butyl, isobutyl pentyl, hexyl, decyl, undecyl and dodecyl radicals, preferably propyl, isopropyl, butyl and isobutyl radicals.
Before use, the alkoxy compounds described above which contain aluminium and/or zinc atoms are generally treated and modified with the initiator polyol (as described in DE 19 748 359).
The following substances are preferably used as catalysts for the subsequent, non-stereospecific reaction of the epoxides with the crystallising polyether polyols which are obtained as an intermediate: alkali hydroxides such as potassium and/or caesium hydroxides, alkaline earth hydroxides such as strontium and/or barium hydroxides, and double metal cyanide (DMC) catalysts (see Kirk-Othmer (3) 18, pages 616 to 645).
Double metal cyanide catalysts which are suitable for the polyaddition of epoxides to the crystallising polyether polyols obtained as intermediates are generally known (see, for example, U.S. Pat. Nos. 3,404,109, 3,829,505, 3,941,849 and 5,158,922). Compared with the conventional production of polyether polyols by means of alkaline catalysts such as alkali hydroxides, the use of these DMC catalysts for the production of polyether polyols results in particular in a reduction of the proportion of monofunctional polyethers comprising terminal double bonds, which are termed monools. DMC catalysts are usually obtained by the reaction of an aqueous solution of a metal salt with the aqueous solution of a metal cyanide salt in the presence of a low molecular weight organic complexing ligand, e.g. an ether. In a typical catalyst preparation, for example, aqueous solutions of zinc chloride (in excess) and potassium hexacyanocobaltate are mixed, and dimethoxyethane (glyme) is subsequently added to the suspension which is formed. After filtration and washing of the catalyst with an aqueous solution of glyme, an active catalyst is obtained, of general formula
Zn
3
[Co(CN)
6
]
2
.x
ZnCl
2
.y
H
2
O.
z
glyme
(see EP 700 949).
Improved DMC catalysts, such as those which are described, for example, in EP-A 700 949, EP-A 743 093, EP-A 761 708, WO 97/40086, WO 98/16310, DE-A 197 45 120, DE-A 197 57 574 and DE-A 198 102 269, possess an extraordinarily high activity in addition and enable polyether polyols to be produced at a very low catalyst concentration, so that it is no longer necessary to separate the catalyst from the polyol.
The epoxides which are preferably used for the addition reaction to the intermediate are propylene oxide, butylene oxide, ethylene oxide or styrene oxide. Propylene oxide is most preferably used. Mixtures of epoxides with each
Gupta Pramod
Hofmann Jörg
Ooms Pieter
Schäfer Walter
Bayer Aktiengesellschaft
Brown N. Denise
Gil Joseph C.
Gorr Rachel
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