Plastic and nonmetallic article shaping or treating: processes – Forming continuous or indefinite length work – Shaping by extrusion
Patent
1997-06-27
1999-11-02
Dixon, Merrick
Plastic and nonmetallic article shaping or treating: processes
Forming continuous or indefinite length work
Shaping by extrusion
2641761, 264180, 26417312, 264339, D01D 514
Patent
active
059764392
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a process for the preparation of an alginate rope, an alginate rope prepared according to that process, a dressing comprising the alginate rope and methods of use thereof.
Alginate fibres have been known for some time as being useful in the preparation of surgical dressings. For example, United Kingdom Patent No. 653341, published in 1951, describes surgical dressings formed from fibres of calcium alginate. The employ of alginate fibres is often desirable over other conventional materials employed in surgical dressings, such as cotton and the like, in view of the superior biocompatibility properties of alginates.
Calcium alginate fibres have subsequently been modified to improve their relative insolubility in water or wound exudate matter. Bonniksen in GB-A-653341 therefore proposed that a proportion of the insolubilising calcium ions in calcium alginate be replaced by solubilising sodium cations. The resulting process has become known as "conversion" of calcium alginate to form a mixed salt alginate. Such mixed salt alginates exhibit a further advantage associated in the employ of alginates in wound treatment, in that such mixed salt alginates having improved solubility in water or wound exudate matter form a protective and useful gel like structure that results over time, and is beneficial to the wound healing process.
Skilled artisans are therefore well aware that it is often desirable to employ alginates in wound dressings and various types of dressing formed from fabrics comprising alginate fibres are therefore known, including non-woven alginate rope. Alginate rope is particularly useful for surgical packing and the management of cavity wounds.
Alginate rope is conventionally prepared via a multistage process involving extruding an aqueous solution of sodium alginate into a calcium ion source, stretching the resulting calcium alginate fibres to between 160 and 250% of their original length, optionally converting a proportion of the calcium ions to sodium ions, then crimping, cutting to staple length, carding and textilling the tow.
Such multistage processes are time consuming and expensive, inter alia, involving the use of multiple spinnerets. Furthermore, alginate ropes produced by conventional techniques as described above generally lack structural integrity which often results in unravelling thereof during use or disintegration on removal from a wound site, whereby residual alginate fibre can be left in the wound site. The residual fibres are generally picked out in tiny pieces, or removed by irrigation, from the wound site. Such removal requires considerable skill, and there is therefore a need for an alginate rope which can be lifted from a wound in one piece. An example of a currently employed alginate rope is available under the trade mark SORBSAN, this SORBSAN rope being a thin sliver which often lacks structural strength and use thereof can therefore be disadvantageous for the reasons described above.
In view of the above lack of structural integrity associated with commercially available alginate rope products, other materials, such as cotton gauze and the like, are often employed in situations where it might have been desirable to employ alginate rope products, such as in the treatment of sinus cavities and the like. Such alternative materials, cotton gauze being a typical example, lack the abovedescribed advantageous biocompatibility or gel-forming properties associated with alginates.
We have now discovered a process of preparation, and a resulting alginate rope product, which alleviate the above problems. In particular, we have discovered a process of preparing an alginate rope which is essentially a single stage process and eliminates the necessity to employ the above described steps of crimping, cutting, carding and textilling the tow. Furthermore, an alginate rope product is provided by the present invention which exhibits greatly improved structural integrity, this being advantageous, inter alia, in handling the dressing before application to a wound
REFERENCES:
Water-Soluble Alginate Salt Fibers and Their Manuf. Using Red. Amts of Org Solv.
Pulp-Based Foam Ropes or Beads and their Manuf.
Fenton John Charles
Griffiths Bryan
Mahoney Peter M. J.
Bristol--Myers Squibb Company
Dixon Merrick
Furman Jr. Theodore R.
Kilcoyne John M.
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