Stable moulding material and spinning material containing cellul

Details Stable moulding material and spinning material containing cellul Stable moulding material and spinning material containing cellul

1994-12-06

1996-01-23

Brunsman, David

Compositions: coating or plastic

Coating or plastic compositions

Carbohydrate or derivative containing

106176, 106186, 106203, C09D10124, C09D10122, C09D10108, C09D10100

Patent

active

054862302

DESCRIPTION:

BRIEF SUMMARY
This application is a 371 of PCT/AT94/00055 filed Apr. 29, 1994
The present invention concerns a stable moulding material and spinning material containing cellulose and an aqueous tertiary amine-oxide. The present invention further concerns the use of special stabilisers for the stabilisation of the cellulose dissolved in a tertiary amine-oxide.
From U.S. Pat. No. 2,179,181 it is known that tertiary amine-oxides have the property of dissolving cellulose and that from these solutions cellulosic fibres may be obtained by precipitation. A process for the preparation of such solutions is known for instance from EP-A-0 356 419. According to this publication, first a suspension of cellulose in an aqueous tertiary amine-oxide is prepared. The amine-oxide contains up to 40% by weight of water. The aqueous cellulose suspension is heated, and while reducing pressure water is withdrawn until the cellulose dissolves.
During dissolving and also during storage of the solution at a higher temperature, a degradation of the cellulose and the solvent occurs. The degradation products may discolour to a considerable extent the moulded bodies, for instance fibres and sheets, obtained after precipitation, and their recovery during recuperation of chemicals may require a considerable effort. The latter however is necessary in order to avoid a pollution of the environment.
EP-A-0 047 929 recommends utilization of gallic acid propyl ester (GPE) as a stabiliser. It has been shown however that the stabilising effect of this compound lasts only a relatively short time, so that a heated cellulose solution has to be processed quickly. Furthermore, GPE is expensive and also its solubility in polar solution media, such as water, leaves something to be desired. It is the objective of the invention to provide a stabiliser which does not exhibit the above drawbacks and is able to stabilise the dissolved cellulose against degradation for a longer period of time than GPE.
According to the invention, this objective is attained by using a mixture of glucosides of gallic acid and m-digallic acid for the stabilisation of the cellulose against degradation.
Further, the invention concerns a stable moulding material and spinning material respectively containing cellulose, a tertiary amine-oxide, particularly N-methylmorpholine-N-oxide (=NMMO), and optionally water, as well as a stabiliser, wherein as said stabiliser a mixture of glucosides of gallic acid and m-digallic acid is provided.
A preferred embodiment of the stable moulding material and spinning material according to the invention contains tannic acid as a stabiliser.
According to dispensatories, tannic acid [CAS 1401-55-4]is defined as a mixture of esters of the D(+) glucose with gallic acid and m-digallic acid. Substances wherein all alcoholic OH groups of the glucose are esterified with gallic acid and m-digallic acid are preferred, being particularly preferred that the m-digallic acid represents a percentage of 40% to 90% of the total of gallic acid and m-digallic acid.
Tannic acid is also present in the so-called tannins, which according to the invention may also be employed as stabilisers. Thus a further preferred embodiment of the stable moulding material and spinning material respectively according to the invention contains tannin as a stabiliser.
Tannins are products which are employed for tanning at an industrial scale. Both vegetable and synthetic substances are used, the vegetable products being obtained by means of extraction from natural materials, such as woods and plants. It has been shown according to the invention that both vegetable tannins and tannic acid itself exhibit good stabilisation properties for cellulose in tertiary amine-oxides. It has been found that under the usual conditions of the preparing of a solution the degradation of cellulose is slowed down and a reduced degradation of the tertiary amine-oxide is observed.
It has been shown that the stabilisers used according to the invention give very good results even at concentrations of no more than 0,05% by weigh

REFERENCES:
patent: 4426228 (1984-01-01), Brandner et al.
patent: 5216144 (1993-06-01), Eichinger et al.

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