Plastic and nonmetallic article shaping or treating: processes – Forming continuous or indefinite length work – Shaping by extrusion
Patent
1997-02-19
1998-09-08
Tentoni, Leo B.
Plastic and nonmetallic article shaping or treating: processes
Forming continuous or indefinite length work
Shaping by extrusion
264178F, 26421114, D01D 506, D01F 202
Patent
active
058041206
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention pertains to a process for making cellulose extrudates from an optically anisotropic solution containing 94-100 wt. % of the following constituents:
Such a process is disclosed in our co-pending patent application based on the Netherlands patent application NL 9401351.
It was found that fibres obtained by extruding and coagulating the solution mentioned in the opening paragraph are particularly susceptible to heat treatment. For instance, it has been found that a heat treatment of 5 minutes at 175.degree. C. can result in the breaking force of the fibres being reduced by about 80% as compared with the original breaking tenacity.
SUMMARY OF THE INVENTION
The susceptibility of the extrudates to a heat treatment can be greatly reduced by the manner of aftertreatment of the extrudates. The invention consists in that in a process of the type mentioned in the opening paragraph the extrudates are aftertreated such that after the aftertreatment the extrudates have a degree of acidity which at least equals 7.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
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 concentration of 8% in a solution of phosphoric acid anisotropy was observed, and anisotropic solutions were still obtained at cellulose concentrations of 40% or higher. Such high concentrations preferably are prepared at elevated temperatures. Selecting a cellulose concentration of more than 8% gives a significantly more economical method of making products from the solutions. Thus anisotropic cellulose solutions can be obtained by selecting a cellulose concentration in the range of about 8 to 40%. Optimum processing of these solutions into fibres was found to be attained in the range of 10 to 30%, preferably 12,5 to 25%, more particularly 15 to 23%. Different fields of application of the solutions may have other optimum concentration ranges.
To obtain the solvent system by means of which anisotropic solutions can be attained, the phosphorus content is determined by converting the quantities by weight of phosphoric acid in the solvent into the equivalent quantities by weight of the corresponding anhydride. Converted in this way, orthophosphoric acid is composed of 72,4% of phosphorus pentoxide and residual water, while polyphosphoric acid H.sub.6 P.sub.4 O.sub.13 is composed of 84% of phosphorus pentoxide and residua
REFERENCES:
patent: 4058411 (1977-11-01), Bellamy et al.
patent: 4839113 (1989-06-01), Villaine et al.
patent: 5368385 (1994-11-01), Adamo et al.
patent: 5571468 (1996-11-01), Meraldi et al.
K. Kamide et al., "Formation and Properties of the Lyotropic Mesophase of the Cellulose/Mixed Inorganic Acid System", Polymer Journal, vol. 25, No. 5, pp. 453-461 (1993).
Derwent Patent Abstract 88-153465/22 (1988).
Derwent Patent Abstract 88-351892/49 (1988).
Patent Abstracts of Japan, vol. 17, No. 42 (C-1020) (1993).
A.S. Chegolya et al., "Production of Regenerated Cellulose Fibers Without Carbon Disulfide", Textile Research Journal 59, Sep. 1989, No. 9, pp. 501-506.
Boerstoel Hanneke
Ypma Marco
Akzo Nobel N.V.
Fennelly Richard P.
Morris Louis A.
Tentoni Leo B.
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