Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From organic oxygen-containing reactant
Reexamination Certificate
2002-01-28
2003-09-09
Truong, Duc (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From organic oxygen-containing reactant
C528S485000, C528S50200C, C528S503000
Reexamination Certificate
active
06617419
ABSTRACT:
This invention relates to long-chain polyether polyols having a high content of primary Oh groups as well as a process for their production by means of double-metal cyanide (DMC) catalysis.
Long-chain polyether polyols having high contents of primary OH groups are required for many polyurethane applications. They are used, for example, in hot and cold mould foaming and in RIM applications (see, for example, Gum, Riese, Ulrich (Eds.): “Reaction Polymers”, Hanser Verlag, Munich, 1992, p.67-70). Long-chain polyether polyols having high contents of primary OH groups are conventionally produced in a two-step process, wherein first of all propylene oxide (or a mixture of propylene oxide and ethylene oxide) is polymerised in the presence of starter compounds having active hydrogen atoms and of a basic catalyst, with a polyether polyol having mainly secondary OH groups being obtained. In the second step, the so-called EO tip, ethylene oxide is then added to the basic polymer, the majority of the secondary OH groups being converted into primary OH groups. In this process the same basic catalyst (for example, KOH) is conventionally used for the propoxylation reaction and for the ethoxylation reaction.
Double-metal cyanide (DMC) catalysts for the production of polyether polyols have been known for a long time (see, for example, U.S. Pat. No. 3,404,109, U.S. Pat. No. 3,829,505, U.S. Pat. No. 3,941,849 and U.S. Pat. No. 5,158,922). Compared with the conventional production of polyether polyols by means of basic catalysts, the use of these DMC catalysts for the production of polyether polyols brings about in particular a decrease in the content of monofunctional polyethers with terminal double bonds, so-called monools. The polyether polyols thus obtained can be processed to form high-quality polyurethanes (for example, elastomers, foams, coatings). Improved DMC catalysts, of the type described, for example, in EP-A 700,949, EP-A 761,708, WO 97/40086, WO98/16310, DE-A 197 45 120, DE-A 197 57 574 and DE-A 198,102,269, possess in addition an exceptionally high activity and render possible the production of polyether polyols at very low concentrations of catalyst (25 ppm or less), so that a separation of the catalyst from the polyol is no longer necessary.
A disadvantage in the use of DMC catalysts for the production of polyether polyols is that with these catalysts, unlike basic catalysts, a direct EO tip is not possible. If ethylene oxide (EO) is added to a poly(oxypropylene) polyol containing a DMC catalyst, the result is a heterogeneous mixture which consists for the most part of unreacted poly(oxypropylene) polyol (having mainly secondary OH groups) and to a small extent of highly ethoxylated poly(oxypropylene) polyol and/or polyethylene oxide. The conventional way of obtaining DMC polyols having a high content of primary OH groups consists, therefore, in carrying out the EO tip in a second, separate step by means of conventional base catalysis (for example, KOH catalysis) (see, for example, U.S. Pat. No. 4,355,188, U.S. Pat. No. 4,721,818, EP-A 750,001). A particular disadvantage of this two-step process is that the basic polymer obtained in the process has to be worked up in a very expensive way, for example, by neutralisation, filtration and dehydration.
U.S. Pat. No. 5,648,559 discloses poly(oxyalkylene) polyols having poly(oxypropylene/-oxyethylene) end blocks, the polyols being produced by DMC catalysis and having a content of primary hydroxyl groups of <50 mol-%. The maximum total content of oxyethylene units in these polyols is 20 wt. %. U.S. Pat. No. 5,700,847 describes poly(oxyalkylene) polyols having up to 25 wt. % oxyethylene units, the latter being containable in mixed blocks or pure poly(oxyethylene) end blocks. The polyols produced without EO tip have <50 mol % of primary OH groups. In U.S. Pat. No. 5,668,191, likewise poly(oxyalkylene) polyols having a maximum of 20 wt. % oxyethylene units and less than 50 mol % of primary hydroxyl groups are used.
It has now been found that long-chain polyether polyols having a content of primary OH groups of >50 mol-% can be obtained by DMC-catalysed polyaddition of an ethylene oxide (EO)/propylene oxide (PO) mixture as an end block to starter compounds having active hydrogen atoms, if the total content of oxyethylene units in the polyol is established at more than 25 wt. %.
The present invention provides long-chain polyether polyols having a content of primary OH groups of 40 to 95 mol-%, preferably 50 to 90 mol %, and a total content of oxyethylene units of more than 25 wt. %, preferably more than 30 wt. %, particularly preferably more than 35 wt. %, which have a poly(oxyethylene/-oxypropylene) end block produced in the presence of a DMC catalyst.
The invention also provides a process for producing the polyols according to the invention by polyaddition of an ethylene oxide (EO)/propylene oxide (PO) mixture in the weight ratio EO:PO of 40:60 to 95:5, preferably 50:50 to 90:10, particularly preferably 60:40 to 90:10, in the presence of DMC catalysts, as an end block to starter compounds having active hydrogen atoms.
The DMC catalysts which are suitable for the process according to the invention are known in principle and are described in detail in the prior art cited above. It is preferable to use improved, highly active DMC catalysts, which are described, for example, in EP-A 700,949, EP-A 761,708, WO 97/40086, WO98/16310, DE-A 197 45 120, DE-A 197 57 574 and DE-A 198,102,269. Typical examples are the DMC catalysts described in EP-A 700,949 which, besides a double-metal cyanide compound (for example, zinc hexacyanocobaltate(III)) and an organic complexing ligand (for example, tert. butanol), also contain a polyether having a number average molecular weight of more than 500 g/mol.
The compounds used as starter compounds having active hydrogen atoms are preferably those with molecular weights of 18 to 2,000 g/mol, preferably 200 to 2,000 g/mol and 1 to 8, preferably 2 to 6, hydroxyl groups. Examples which may be given are butanol, ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,4-butanediol, 1,6-hexanediol, bisphenol A, trimethylolpropane, glycerol, pentaerythritol, sorbitol, cane sugar, degraded starch or water.
It is more advantageous to use those starter compounds having active hydrogen atoms which have been prepared from the above-mentioned low-molecular starters, for example, by conventional alkaline catalysis and are oligomeric alkoxylation products with number average molecular weights of 200 to 2,000 g/mol.
Compounds preferably used are oligonmeric propoxylated starter compounds having 1 to 8 hydroxyl groups, particularly preferably 2 to 6 hydroxyl groups, and number average molecular weights of 200 to 2,000 g/mol.
By DMC-catalysed polyaddition to an ethylene oxide/propylene oxide mixture in the weight ratio EO:PO of 40:60 to 95:5, preferably 50:50 to 90:10, particularly preferably 60:40 to 90:10, as end block, the starter compounds having active hydrogen atoms can be directly converted into a long-chain polyether polyol having a high content of primary OH groups and a content of oxyethylene units of >25 wt. %, preferably >30 wt. %, particularly preferably >35 wt. %.
It is preferred, however, first of all to extend the starter compound by DMC-catalysed propoxylation, preferably to a number average molecular weight of between 500 and 15,000 g/mol, and subsequently, from this extended propoxylated intermediate, by DMC-catalysed polyaddition to an ethylene- oxide/propylene oxide mixture in the weight ratio EO:PO of 40:60 to 95:5, preferably 50:50 to 90:10, particularly preferably 60:40 to 90:10, as end block, to produce a long-chain polyether polyol having a high content of primary OH groups and a content of oxyethylene units of >25 wt. %, preferably >30 wt. %, particularly preferably >35 wt. %.
In this case the process according to the invention is particularly preferably carried out as a so-called “one-pot reaction” wherein, after the DMC-catalysed propoxylation, without in
Dietrich Manfred
Gupta Pramod
Hofmann Jörg
Bayer Aktiengesellschaft
Gil Joseph C.
Mrozinski, Jr. John E.
Truong Duc
LandOfFree
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