Patent GB-977708-A (GB)
Title: Non-woven fabrics
IPC: D04H1/4266
Filed: 1960-01-04
Abstract: A non-woven fabric comprises a web of fibres wholly or partly impregnated with a bonding agent containing a "curable polyamino derivative of a carbohydrate," i.e. a polyamino derivative of a carbohydrate which either spontaneously or through the influence of certain agencies, e.g. heat or chemical action, undergoes a change to effect an increase in strength of the fabric.  The web may be isotropic or oriented, e.g. by carding, and may comprise natural or synthetic fibres.  Specified fibres are of cotton, wool, silk, viscose rayon, cellulose acetate, cellulose triacetate, polyamides (e.g. nylon) polyacrylics, polyvinyl chloride acrylonitrile copolymers, polyesters and vinylidene chloride polymers.  The web may be impregnated with bonding agent over its entire area or the binding agent may be applied by printing in a predetermined pattern.  A specified polyamino derivative is chitosan (i.e. partially deacetylated chitin) which may be applied dissolved in an aqueous solution, of organic or inorganic acid.  Specified acids are acetic and formic acids. Chitosan may be used in admixture with other bonding agents such as polyvinyl acetate, polyvinyl alcohol, starch and starch ethers. Curing of the chitosan takes place spontaneously, but slowly, at ordinary temperatures; it may be accelerated by heating, for example to 118 DEG  C. whereby the fabric is also sterilized, or by treating the impregnated web with a curing agent such as ammonia or other alkali in aqueous solution, carboxy methyl cellulose, aldehydes and sulphonates.  To reduce viscosity the chitosan solutions may have additions of oxidizing agents such as hydrogen peroxides.  Biologically active substances such as biocide, or dyes, or materials which change colour on heating to sterilizing temperature may also be incorporated.  The products may be used as, or as components of, sanitary towels, surgical dressings, disposable napkins and diapers, filters, towels, handkerchiefs and cloths, ironing board covers, and hospital bed sheets and pillow cases.  In examples (a) a fabric usable as covers for sanitary towels was made by foraminating a web of viscose rayon by means of water jets while supported on an apertured plate, applying a solution of chitosan in formic acid by means of a diamond patterned engraved roller, and drying at 110 DEG  C. on a heated cylinder; (b) covers for medical absorbent pads were made from a web 8 of a mixture of oriented cotton and rayon fibres printed wet with a bonding agent as is (a) applied with a roller engraded with wavy lines, and cured at 118 DEG  C.; (c) a two-ply web of viscose rayon fibres printed in wavy lines with a mixture of chitosan in acetic acid and polyvinyl alcohol in water and cured at 110 DEG  C. was used for making disposable pillow cases for hospitals; (d) a web of viscose rayon fibres was impregnated with a mixture of amylopectin and chitosan dissolved in formic acid, cured and used as a stiffener for clothing.  Specifications 836,397, 843,041, 843,051 and 923,963 are referred to.ALSO:A non-woven fabric comprises a web of fibres wholly or partly impregnated with a bonding agent containing a "curable polyamino derivative of a carbohydrate", i.e. a polyamino derivative of a carbohydrate which either spontaneously or through the influence of certain agencies e.g. heat or chemical action, undergoes a change to effect an increase in strength of the fabric.  The web may be isotropic or oriented e.g. by carding and may comprise natural or synthetic fibres.  Specified fibres are of cotton, wool, silk, viscose rayon, cellulose acetate, cellulose triacetate, polyamides (e.g. nylon) polyacrylics, polyvinyl chloride-acrylonitrile copolymers, polyesters and vinylidene chloride polymers.  The web may be impregnated with bonding agent over its entire area or the binding agent may be applied by printing in a predetermined pattern.  A specified polyamino derivative is chitosan, (i.e. partially deacetylated chitin) which may be applied dissolved in an equeous solution, of organic or inorganic acid.  Specified acids are acetic and formic acids. Chitosan may be used in admixture with other bonding agents such as polyvinyl acetate, polyvinyl alcohol, starch and starch ethers.  Curing of the chitosan takes place spontaneously, but slowly, at ordinary temperatures; it may be accelerated by heating, for example to 118 DEG C. whereby the fabric is also sterilized, or by treating the impregnated web with a curing agent such as ammonia or other alkali in aqueous solution, carboxy methyl cellulose, aldehydes and sulphonates.  To reduce viscosity the chitosan solutions may have additions of oxidizing agents such as hydrogen peroxides.  Biologically active substances such as biocide, or dyes, or materials which change colour on heating to sterilizing temperature may also be incorporated.  The products may be used as, or as components of, sanitory towels, surgical dressings, disposable napkins and diapers, filters, towels, handkerchiefs and cloths, ironing board covers, and hospital bed sheets and pillow cases.  In examples (a) a fabric usable as covers for sanitary towels was made by foramenating a web of viscose rayon by means of water jets while supported on an apertured plate, applying a solution of chitosan in formic acid by means of a diamond patterned engraved roller, and drying at 110 DEG C. on a heated cylinder; (b) covers for medical absorbent pads were made from a web of a mixture of oriented cotton and rayon fibres printed wet with a bonding agent as in (a) applied with a roller engraved with wavy lines, and cured at 118 DEG C.; (c) a two-ply web of viscose rayon fibres printed in wavy lines with a mixture of chitosan in acetic acid and polyvinyl alcohol in water and cured at 110 DEG C. was used for making disposable pillow cases for hospitals; (d) a web of viscose rayon fibres was impregnated with a mixture of amylopectin and chitosan dissolved in formic acid, cured and used as a stiffener for clothing.  Specifications 836,397, 843,041, 843,051 and 923,963 are referred to.