Bleaching and dyeing; fluid treatment and chemical modification – Chemical modification of textiles or fibers or products thereof – Proteinaceous fibers
Patent
1993-02-04
1997-12-16
Diamond, Alan
Bleaching and dyeing; fluid treatment and chemical modification
Chemical modification of textiles or fibers or products thereof
Proteinaceous fibers
81281, 8110, 8111, D06M 1150
Patent
active
056979835
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a method for the treatment of wool so as to impart shrink resistance, and which involves treating the wool with both hydrogen peroxide and permonosulphuric acid.
Many ways of rendering wool shrink resistant are known. These typically involve subjecting the wool to an oxidative treatment alone or, more commonly nowadays, followed by a polymer treatment.
Various two-step shrink-proofing processes in which wool is treated first with a chlorinating oxidative agent and subsequently with a pre-formed synthetic polymer have been developed. A wide variety of polymers can be used in aqueous solution or dispersion, including polyamide-epichlorohydrin resins and polyacrylates. A review of work in this field by J. Lewis appears in Wool Science Review, Nay 1978, pages 23-42. British Patent Nos. 1,074,731 and 1,340,859, U.S. Pat. Nos. 2,926,154 and 2,961,347 and European Patent Application No. 0129322A, for example, describe two-step shrink-proofing processes and resins or polymers suitable for use therein.
A number of chlorinating oxidative treatments, or pre-treatments, for use on wool are well known. The source of chlorine may be chlorine gas supplied from cylinders, or chlorinating agents such as hypochlorite and dichloroisocyanuric acid and their salts. For example, British Patent No. 569,730 describes a batch shrink-proofing treatment involving hypochlorite and potassium permanganate; British Patent No. 2,044,310 describes a treatment with an aqueous solution of permanganate and hypochlorite. In all cases the active principle remains the same.
Non-chlorine oxidative treatments, or pre-treatments, for use on wool have been known for some time. Hydrogen peroxide on its own confers a very weak shrink resist effect to wool, but this has never been sufficient to merit its commercial use as a practical anti-shrink treatment. In a treatment known as the Perzyme Process, wool is first bleached with hydrogen peroxide and then treated with a mixture of the enzyme papain and sodium bisulphite. The disadvantages of this process are that the wool suffers a weight loss during the treatment, the handle of the wool deteriorates and the treatment is slow and not so easily applied to wool tops as to yarns and fabrics.
Permonosulphuric acid and its salts have been known for some time to confer reasonable levels of shrink resistance to wool either when used alone, as disclosed in British Patent No. 1,084,716, or in combination with a chlorinating agent, as disclosed in British Patent No. 1,073,441. British Patent No. 738,407 describes a process for the manufacture of permonosulphuric acid from hydrogen peroxide and concentrated sulphuric acid. The product is said to be suitable for use as a bleaching agent and various other purposes. British Patent Nos. 872,292 and 991,163 disclose processes for the shrink-proofing of wool which comprise treating the wool with permonosulphuric acid and a permanganate, or with an aqueous solution of permonosulphuric acid at a temperature in excess of 70.degree. C., respectively. British Patent No. 1,071,053 describes a treatment for imparting shrink resistance to wool which comprises first applying an aqueous solution of permonosulphuric acid, or a salt thereof, and subsequently treating the wool with an aqueous solution of hydrogen peroxide. The teaching is limited to a sequential or two-step treatment and the level of shrink resistance achieved is, by today's standards, very low. British Patent No. 1,118,792 describes a shrink resist treatment which comprises treating the wool with permonosulphuric acid, a permanganate and dichloroisocyanuric acid or trichloroisocyanuric acid and, optionally, also with sulphurous acid or a salt thereof.
Of the above-mentioned non-chlorine treatments, permonosulphuric acid is preferred as it imparts a much higher standard of washability when used alone than does hydrogen peroxide. Peroxide treatments for the purpose of bleaching wool are performed at a pH of from 5.0 to 10.0, typically pH 7.5 to 8.5. Normal bleaching takes anything from 1 to
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Connell David Longley
Huddlestone Kenneth Michael
Diamond Alan
Precision Processes Textiles
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