Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – From heterocyclic reactant containing as ring atoms oxygen,...
Reexamination Certificate
2003-01-02
2004-07-20
Sellers, Robert (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
From heterocyclic reactant containing as ring atoms oxygen,...
C528S413000, C528S421000
Reexamination Certificate
active
06765082
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a process for the preparation of highly-branched polyols by polymerisation of glycidol in the presence of a hydrogen-active starter compound with basic catalysis.
Branched polyols based on glycidol are conventionally prepared by reacting glycidol with a hydroxyl-containing compound, for example, glycerol, in the presence of inorganic (JP-A 61-43627) or organic (JP-A 58-198429) acids as catalysts. The polymers thus obtained generally have a low degree of polymerisation. The polymerisation of glycidol to products of higher molecular weight which have a narrow molar-mass distribution and complete incorporation of initiators cannot be achieved by cationic catalysis, because of the competing cyclisation reactions (Macromolecules, 27 (1994) 320; Macromol Chem. Phys. 196 (1995) 1963). Existing processes using basic catalysis (EP-A 116 978; J. Polym. Sci., 23(4) (1985) 915), likewise do not lead to colourless products free of by-products and having a narrow molar-mass distribution and complete incorporation of initiators. A secondary reaction of significance here is in particular the cyclisation as a result of the autopolymerisation of glycidol.
SUMMARY OF THE INVENTION
Accordingly, the object of the present invention was to find a process for the preparation of highly-branched polyols based on glycidol whereby the problems described above are avoided.
Surprisingly, it has now been found that it is possible to prepare colourless, highly-branched polyols based on glycidol which are narrowly distributed and have a defined structure, if a dilute solution containing glycidol is added to a hydrogen-active starter compound, with basic catalysis, the solvent used for the dilution being continuously distilled off. In this connection, “defined structure” means that each molecule possesses the initiator (hydrogen-active starter compound) as the core unit and the degree of polymerisation can be controlled via the monomer/initiator ratio.
The invention provides a process for the preparation of highly-branched polyols based on glycidol which have a defined structure, which is characterised in that a dilute solution containing glycidol is added to a hydrogen-active starter compound, in the presence of a basic catalyst, the solvent used for the dilution of the monomer being continuously distilled off.
As a result of the preferential opening of the epoxide ring at the unsubstituted end where basic catalysis is used, a secondary alkoxide is first of all produced, which, however, in consequence of the basic catalysis, is in rapid exchange with the primary alkoxide. The rapid proton exchange equilibrium ensures that all hydroxyl groups present in the system are active as regards polymerisation and that there is a resulting development of branching.
DETAILED DESCRIPTION OF THE INVENTION
Compounds having molecular weights of from 18 to 4,000 and containing from 1 to 20 hydroxyl, thiol and/or amino groups are used as hydrogen-active starter compounds. Examples which may be given are: methanol, ethanol, butanol, phenol, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, 1,2-propylene glycol, dipropylene glycol, polypropylene glycol, 1,4-butanediol, hexamethylene glycol, bisphenol A, trimethylolpropane, glycerol, pentaerythritol, sorbitol, cane sugar, degraded starch, water, methylamine, ethylamine, propylamine, butylamine, stearylamine, aniline, benzylamine, o- and p-toluidine, &agr;,&bgr;-naphthylamine, ammonia, ethylenediamine, propylenediamine, 1,4-butylenediamone, 1,2-, 1,3-, 1,4-, 1,5- or 1,6-hexamethylenediamine, also o-, m- and p-phenylenediamine, 2,4-, 2,6-tolylenediamine, 2,2′-, 2,4- and 4,4′-diaminodiphenylmethane and diethylenediamine, as well as compounds which contain functionalisable starter groups, such as, for example, allyl glycerol, 10-undecenylamine, dibenzylamine, allyl alcohol, 10-undecenol. The starter compound is first of all partially deprotonated by a suitable reagent, for example, by alkali metals or alkaline-earth metals, their hydrides, alkoxides, hydroxides or alkyls. Preferably alkali metal hydroxides or alkoxides or alkaline-earth metal hydroxides or alkoxides are used, such as, for example, potassium hydroxide or methoxide. Any reactive, volatile reaction products (for example, water, alcohol) which may form in the course of this are removed (for example, by distillation). Degrees of deprotonation are generally 0.1% to 90% and preferably 5% to 20%. In order to avoid problems of intermixture in the course of the reaction, the basic initiator system thus prepared is dissolved or dispersed, preferably under inert gas (for example, N
2
, Ar), in an inert solvent I (0.1 to 90 wt. %, based on the quantity of the end product) having a boiling point at least 5° C. above the reaction temperature. Solvent I can be an aliphatic, cycloaliphatic or aromatic hydrocarbon (for example, Decalin, toluene, xylene) or an ether (for example, glyme, diglyme, triglyme), preferably diglyme, as well as mixtures of these. The monomer is added in a solution, which generally contains 80 to 0.1 wt. % and preferably 50 to 1 wt. % glycidol in an inert solvent II. Solvent II can be an aliphatic, cycloaliphatic or aromatic hydrocarbon (for example, hexane, cyclohexane, benzene) or an ether (for example, diethyl ether, THF), preferably THF, or a mixture of these, the boiling point being at least 1° C. below the reaction temperature. Solvent II can contain other additives, such as stabilisers and up to 10 wt. %, based on the solvent, of other comonomers such as, for example, propylene oxide, ethylene oxide, butylene oxide, vinyl oxirane, ally glycidyl ether, isopropyl glycidyl ether, phenyl glycidyl ether. Solvent II must be a solvent for glycidol, but not necessarily for the polyol. The monomer solution is slowly added to the mixture of initiator and solvent I, preferably under inert gas (for example, N
2
, Ar). The feed rate is so chosen as to ensure a good temperature control at the given reaction conditions of reaction temperature, glycidol concentration, hydroxyl and catalyst concentration. In the course of the reaction solvent II is continuously removed from the reaction mixture by distillation. Here the reaction temperatures are generally 40° C. to 180° C., preferably 80° C. to 140° C. The reaction is preferably carried out at normal pressure or reduced pressure. In the course of the reaction, depending on the choice of solvents I and II, the reaction mixture may become inhomogeneous. This does not influence the reaction, however, as long as no precipitation occurs. In order to work up the alkaline polymer, in principle all the known techniques for the working up of polyether polyols for applications in polyurethane chemistry may be used (H. R. Friedel, in Gum, W. F., Riese, W. (Editors): “Reaction Polymers”, Hanser Verlag, Munich 1992, page 79). The polyol is worked up preferably by neutralisation. For this, the alkaline polymer can first of all be dissolved in a suitable solvent (for example, methanol). The neutralisation is preferably carried out by acidification with dilute mineral acid (for example, sulfuric acid) with subsequent filtration or treatment with adsorbent material (for example, magnesium silicate), particularly preferably by filtration through acidic ion-exchange material. This can be followed by a further purification by precipitation (for example, from methanol in acetone). Finally, the product is freed from traces of solvents under vacuum at temperatures of 20° C. to 200° C.
The polymerisation can be carried out in a system of reactors consisting of three essential components: a heatable reaction vessel with mechanical stirrer, a metering unit and a system for the removal of solvents.
The polyols thus prepared, which are the subject matter of the Application, have degrees of polymerisation (based on one active hydrogen atom of the initiator) of 1 to 300, preferably of 5 to 80. The molar mass of the polyols according to the invention can be controlled via the monomer/initiator ratio correspon
Mülhaupt Rolf
Sunder Alexander
Bayer Aktiengesellschaft
Brown N. Denise
Gil Joseph C.
Sellers Robert
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