Organic compounds -- part of the class 532-570 series – Organic compounds – Carbohydrates or derivatives
Patent
1997-02-25
1998-10-06
Nutter, Nathan M.
Organic compounds -- part of the class 532-570 series
Organic compounds
Carbohydrates or derivatives
536124, D01F 202, C08B 100
Patent
active
058178015
DESCRIPTION:
BRIEF SUMMARY
The invention pertains to an optically anisotropic solution containing cellulose and inorganic acids of phosphorus, a process for preparing such solutions, the making of products therefrom, and the products thus obtained.
Japanese patent publication JP 4258648 discloses cellulose solutions in which at least cellulose, water, and a mixture of two acids are employed. The description states that, in order to effect proper dissolution of the cellulose, the solvent may not contain in excess of 85 wt. % of ortho-, meta-, pyro-, or polyphosphoric acid. Cellulose solutions exhibiting optical anisotropy are obtained by mixing sulphuric acid, ortho- or polyphosphoric acid, and water in a weight ratio of 10-20/70-80/10-20 and dissolving at least 15 wt. % of cellulose therein.
Such optically anisotropic solutions containing cellulose and an inorganic acid of phosphorus are also described in an article by K. Kamide et al. of Asahi Chemical Industry Co., "Formation and Properties of the Lyotropic Mesophase of the Cellulose/Mixed Inorganic Acid System," Polymer Journal Vol. 25, No. 5 (1993), 453-461. This article clearly indicates that anisotropic solutions can only be obtained with a mixture of sulphuric acid/polyphosphoric acid/water as solvent and at least 16 wt. % of cellulose.
Sulphuric acid has a highly oxidative effect on cellulose, causing it to degradate. In addition, the use of sulphuric acid promotes corrosion and so is less advisable for industrial applications. A further drawback consists in that the use of a mixture of different acids such as sulphuric acid and phosphoric acid is disadvantageous in industrial applications, while recovering the solvent after manufacture of the product from a solvent system containing several acids was likewise found to be disadvantageous. The system as mentioned in the aforesaid article does not permit a great deal of control over major process settings, since with only one anisotropic system being deemed feasible, the viscosity and the proper temperature are all but fixed.
The present invention relates to an anisotropic solution of cellulose which obviates the aforementioned drawbacks. The invention relates to an anisotropic solution according to the preamble of the claim, and is characterised in that the solution contains 94-100 wt. % of the following constituents:
In the present patent specification the solvent is made up, by definition, of the added phosphoric acid and/or anhydrides thereof, and all the water present in the solution which is not chemically bonded. For that reason, water derived from the cellulose that is generally added at a later time is always considered to be part of the solvent in this description, as is water from substances which are among "other constituents", which substances may be added at any time during the preparation of the solution.
The term phosphoric acid in this application stands for all inorganic acids of phosphorus, including mixtures thereof. Orthophosphoric acid is an acid of pentavalent phosphorus, i.e., H.sub.3 PO.sub.4. The anhydrous equivalent thereof, i.e., the anhydride, is also known as phosphorus pentoxide (P.sub.2 O.sub.5). Depending on the amount of water in the system, there is, in addition to orthophosphoric acid and phosphorus pentoxide, a series of pentavalent phosphoric acids with a water-binding capacity between the pentoxide and the ortho-acid. Alternatively, solvents of, say, orthophosphoric acid with a concentration of orthophosphoric acid of less than 100% may be used.
Due to some reaction between the phosphoric acid and the cellulose, the solution may contain phosphorus derivatives of cellulose. These derivatives of cellulose are also considered to belong to the constituents making up 94-100 wt. % of the solution. Where the percentages by weight of cellulose in solution listed in this patent specification concern phosphorus derivatives of cellulose, they relate to quantities calculated back on the cellulose. The same holds for the amounts of phosphorus mentioned in this specification.
Already at a cellulose con
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Boerstoel Hanneke
Koenders Bernardus Maria
Westerink Jan Barend
Akzo Nobel NV
Fennelly Richard P.
Morris Louis A.
Nutter Nathan M.
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