Anti-Microbial Fibres and Their Production

Abstract

Anti-microbial lyocell fibres incorporate an anti-microbial composition which comprises a silver compound deposited on a support material in the form of porous particles having an extended surface area and comprising an oxidic material which is essentially insoluble in water and incapable of forming hydrates. A preferred composition is silver chloride on titanium dioxide particles. The anti-microbial effect is durable to processing and the fibres are not adversely discoloured. Low concentrations of the anti-microbial composition of below 0.1 percent by weight on weight of cellulose may be used. In the process of making the fibres, the anti-microbial composition preferably is added to the pasty pre-mix of the spinning solution.

1 . Anti-microbial lyocell fibres incorporating anti-microbial composition which includes a silver compound held on a support material, characterized in that the anti-microbial composition comprises a silver compound deposited on a support material in the form of porous particles having an extended surface area and comprising an oxidic material which is essentially insoluble in water and incapable of forming hydrates.  
   
   
       2 . Anti-microbial lyocell fibres according to  claim 1 , characterized in that the oxidic support material is selected from oxides of titanium, magnesium, aluminum, silicon, cerium, zirconium, hafnium, niobium and tantalum, calcium hydroxyapatite and barium sulphate.  
   
   
       3 . Anti-microbial lyocell fibres according to  claim 1 , characterized in that the oxidic support material is titanium dioxide in one or more of the crystalline forms anatase, rutile and brookite.  
   
   
       4 - 10 . (canceled)  
   
   
       11 . A process for making anti-microbial lyocell fibres by dissolving cellulose in a solvent of aqueous tertiary amine N-oxide to form a spinning solution, extruding the spinning solution through a spinning jet into a coagulation bath to produce lyocell fibres, and incorporating an anti-microbial composition into the fibres, characterized in that the anti-microbial composition is added to the spinning solution or to a precursor or ingredient of that solution and comprises a silver compound deposited on a support material in the form of porous particles having an extended surface area and comprising an oxidic material which is essentially insoluble in water and incapable of forming hydrates.  
   
   
       12 . A process according to  claim 11 , in which the spinning solution is made by forming a precursor comprising a pre-mix of cellulose pulp and aqueous amine oxide solvent having excess water over the optimum required for solution to take place, characterized in that the anti-microbial composition is added to the pre-mix, and water is then evaporated from the pre-mix to form the spinning solution having the anti-microbial agent dispersed therein.  
   
   
       13 - 14 . (canceled)  
   
   
       15 . A process according to  claim 12 , wherein the anti-microbial composition is added in the form of a dispersion in a liquid.  
   
   
       16 . A process according to  claim 15 , wherein the lyocell fibres are subjected to one or more treatments comprising scouring or washing to substantially remove any residual colouration formed during the fibre-making process.  
   
   
       17 . A process according to  claim 11 , wherein the anti-microbial composition is added in the form of a dispersion in a liquid.  
   
   
       18 . A process according to  claim 11 , wherein the lyocell fibres are subjected to one or more treatments comprising scouring or washing to substantially remove any residual colouration formed during the fibre-making process.  
   
   
       19 . Anti-microbial lyocell fibres according to  claim 1 , wherein the porous particles comprising the oxidic support material have an average particle diameter below 25 microns.  
   
   
       20 . Anti-microbial lyocell fibres according to  claim 19 , wherein the porous particles have a surface area in the range 1 to 240 square metres per gram.  
   
   
       21 . Anti-microbial lyocell fibres according to  claim 1 , wherein the porous particles have a surface area in the range 1 to 240 square metres per gram.  
   
   
       22 . Anti-microbial lyocell fibres according to  claim 1 , wherein the silver compound has a low solubility in water and has silver present as an ionic species.  
   
   
       23 . Anti-microbial lyocell fibres according to  claim 22 , wherein the silver compound is at a level of concentration of 1 to 75 percent by weight of the oxidic support material.  
   
   
       24 . Anti-microbial lyocell fibres according to  claim 23 , wherein the silver compound comprises silver chloride.  
   
   
       25 . Anti-microbial lyocell fibres according to  claim 1 , wherein the silver compound is at a level of concentration of 1 to 75 percent by weight of the oxidic support material.  
   
   
       26 . Anti-microbial lyocell fibres according to  claim 1 , wherein the silver compound comprises silver chloride.  
   
   
       27 . Anti-microbial lyocell fibres according to  claim 3 , wherein the silver compound comprises silver chloride.  
   
   
       28 . Anti-microbial lyocell fibres according to  claim 1 , wherein the anti-microbial composition is in a concentration in the fibres of below 1 percent by weight owc.  
   
   
       29 . Anti-microbial lyocell fibres according to  claim 28 , wherein the anti-microbial composition is in a concentration in the fibres of below 0.1 percent by weight owc.