Compositions: coating or plastic – Coating or plastic compositions – Carbohydrate or derivative containing
Patent
1984-02-08
1986-04-08
Lieberman, Allan M.
Compositions: coating or plastic
Coating or plastic compositions
Carbohydrate or derivative containing
106177, 106186, 106311, C08K 320, C08K 332, C08L 102
Patent
active
045810729
DESCRIPTION:
BRIEF SUMMARY
This invention relates to the stabilisation of hydrated tertiary amine N-oxides suitable as solvents for organic polymers and of solutions of organic polymers, particularly cellulose, in such solvents. The polymer solutions may be used as spinning or casting dopes for making shaped polymer articles such as fibres or films, and the invention includes a process for making such articles.
Hydrated tertiary amine N-oxides (hereinafter referred to on occasion as `amine oxides` for convenience) are susceptible to degradation, particularly at elevated temperatures and at certain lower levels of hydration, both of which are conditions which favour the dissolution of organic polymers in the amine oxides. Degradation results in a loss of amine oxide, which is an expensive solvent, and can give rise to discolouration of the solvent and any polymer dissolved in it.
Degradation of the amine oxide solvent may also be accompanied by degradation of an organic polymer dissolved in that solvent. In the case of cellulose, there can be a significant reduction in the degree of polymerisation during dissolution at elevated temperatures and during any subsequent interval before the cellulose is regenerated.
According to this invention, a solvent for organic polymers comprises a hydrated tertiary amine N-oxide characterised by the incorporation therein as a stabilising additive of one or more compounds selected from phosphoric acids, phosphate salts, phosphonic acids, phosphonate salts, and complexes of any of the foregoing with occluded metal ions. the invention having an organic polymer dissolved therein. The preferred organic polymer is cellulose.
The added salt or acid stabilises the amine oxide and any dissolved organic polymer by substantially reducing the rate of degradation reactions. It is believed that these are mainly oxidation reactions catalysed by occluded metal ions in the system, usually iron, and that the added acid or salt complexes with these ions to effectively remove the catalyst.
The level of additive required to give the desired stability depends upon a number of factors including the occluded metal ion concentration, the time taken to form an organic polymer solution in the amine oxide and to regenerate the organic polymer from that solution, and the temperature to which the solution is heated as the organic polymer is being dissolved. Reduced processing times reduce the extent of degradation, and reduced temperatures and occluded metal ion concentrations reduce the rate of degradation.
In general, up to 3.0 percent by weight of stabilising additive is sufficient, with a preferred range being 0.1 to 1.0 percent by weight. In the case of solutions of cellulose, we have found that with commercial grades of wood pulp and amine oxides, and local mains water, a concentration of stabilising additive of 1 percent by weight of less can give satisfactory stabilisation under conditions chosen to represent those encountered in dope preparation for a fibre spinning process.
Phosphoric and phosphonic acids and their salts have the advantage compared with other potential complexing agents for occluded metal ions that they do not in general form coloured complexes, particularly with iron, so that polymeric fibres or films, regenerated from solution are not stained. Suitable acids and salts include disodium hydrogen phosphate, potassium dihydrogen phosphate, sodium hexametaphosphate, hydroxyethylidene diphosphonic acid, and aminoethyl disphosphonic acid. Sodium hexametaphosphate is the preferred stabilising additive.
Hydrated tertiary amine N-oxides which are suitable solvents for cellulose and other organic polymers are described in U.S. Pat. No. 2,179,181 and British Pat. No. 1,144,048, which are incorporated herein by reference, and such amine oxides can be used in the present invention. The latter patent describes cyclic tertiary amine N-oxides and these are the preferred solvents used in the present invention, particularly N-methyl morpholine N-oxide which combines effectiveness as a solvent with thermal stability.
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REFERENCES:
patent: 3332999 (1968-07-01), Mitchell et al.
patent: 3447939 (1969-06-01), Johnson
patent: 3489687 (1970-01-01), Inamorato et al.
patent: 3810769 (1974-05-01), Blacker et al.
patent: 4075163 (1978-02-01), Hofer et al.
patent: 4076690 (1978-02-01), Rosenberger
patent: 4144080 (1979-03-01), McCorsley, III
patent: 4290815 (1981-09-01), Henry
patent: 4338216 (1982-07-01), Earl et al.
Courtaulds PLC
Lieberman Allan M.
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