Method and apparatus for dyeing cellulosic textile substrates with an inert leuco state dye and dyed product

Abstract

Dyeing a cellulosic textile substrate with reduced indigo dye in a leuco state after foaming with an inert gas to maintain the dye isolated from oxidizing substances. Following application of the foam to the substrate, it is exposed to the adjacent atmosphere, with the oxygen in the atmosphere oxidizing the reduced indigo dye to regenerate it and cause it to affix to the textile substrate. A product can be produced using the method and apparatus of the present invention that has different dye characteristics on opposite surfaces of the substrate by applying the indigo dye foam to one surface and another dye, either an indigo dye or some other dye to the opposite surface.

1 . A method of dyeing a cellulosic textile substrate comprising: providing a supply of reduced dye in a leuco state, substantially isolating said leuco state dye from oxidizing substances, generating a foam of said leuco state dye and an inert gas while maintaining said dye in said leuco state, applying said foam to at least one surface of said substrate, and exposing said applied foam to an oxidizing substance to regenerate said dye and affix said dye to said textile substrate.  
   
   
       2 . A method of dyeing a cellulosic textile substrate according to  claim 1  wherein said cellulosic textile material is a woven fabric.  
   
   
       3 . A method of dyeing a cellulosic textile substrate according to  claim 1  wherein said cellulosic textile material is cotton.  
   
   
       4 . A method of dying a cellulosic textile substrate according to  claim 3  wherein said reduced dye is an indigo dye in leuco state.  
   
   
       5 . A method of dyeing a cellulosic textile substrate according to  claim 1  wherein said cellulosic textile material is in the form of a rope of yarn.  
   
   
       6 . A method of dyeing a cellulosic textile substrate according to  claim 4  wherein said cotton material is in the form of a sheet of warp yarns for weaving denim fabric.  
   
   
       7 . A method of dyeing a textile substrate according to  claim 4  wherein said cotton textile material is in the form of a denim fabric.  
   
   
       8 . A method of dyeing a cellulosic textile substrate according to  claim 4  wherein said indigo dye comprises indigo paste diluted in water.  
   
   
       9 . A method of dyeing a cellulosic textile substrate according to  claim 8  wherein said indigo dye comprises indigo paste at a concentration of approximately 40% or less.  
   
   
       10 . A method of dyeing a cellulosic textile substrate according to  claim 1  wherein said isolating said leuco state dye from oxidizing substances comprises containing the supply of reduced dye in a closed container with an inert gas covering the top surface of the dye in said container.  
   
   
       11 . A method of dyeing a cellulosic textile substrate according to  claim 10  in which the inert gas is nitrogen.  
   
   
       12 . A method of dyeing a cellulosic textile substrate according to  claim 1  wherein isolating said leuco state dye from oxidizing substances comprises containing the supply of reduced dye in a container with a cover floating on said dye and substantially covering the top surface of said dye.  
   
   
       13 . A method of dyeing a cellulosic textile substrate according to  claim 12  wherein the container is a closed container and an inert gas is provided in the container above said floating cover.  
   
   
       14 . A method of dyeing a cellulosic textile substrate according to  claim 13  in which the inert gas is nitrogen.  
   
   
       15 . A method of dyeing a cellulosic textile substrate according to  claim 1  wherein the exposing is exposing to the atmosphere.  
   
   
       16 . A method of dyeing a cellulosic textile substrate according to  claim 1  wherein said foam is applied to both surfaces of said substrate.  
   
   
       17 . A method of dyeing a cellulosic textile substrate according to  claim 1  wherein said foam is applied to only one surface of said substrate.  
   
   
       18 . A method of dyeing a cellulosic textile substrate according to  claim 1  wherein said foam contains a first dye applied to one surface of said textile substrate, and a second dye having at least one characteristic different from that of the first dye is applied to the opposite surface of said textile substrate.  
   
   
       19 . A method of dyeing a cellulosic textile substrate according to  claim 18  wherein said different characteristic is a difference in color or shade.  
   
   
       20 . A method of dyeing a cellulosic textile substrate according to  claim 19  wherein said other dye is a reduced dye applied in a leuco state in a foamed condition.  
   
   
       21 . A method of dyeing a cellulosic textile substrate according to  claim 20  wherein both said first and said second dyes are indigo dyes.  
   
   
       22 . A method of dyeing a cellulosic textile substrate according to  claim 1  wherein said foam generating is performed at a blow ratio in the range of 0.01:1 to 50:1.  
   
   
       23 . A method of dyeing a cellulosic textile substrate according to  claim 1  wherein said foam generating is performed at a blow ratio of approximately 3:1.  
   
   
       24 . A method of dyeing a cellulosic textile substrate in an apparatus having a container for receiving reduced dye in a leuco state, a foam generator, and an applicator, said method comprising purging the apparatus with a fluid that does not contain oxygen to remove any oxygen from the apparatus, providing a supply of reduced dye in a leuco state in said container while substantially isolating said leuco state dye from oxidizing substances, a generating in said foam generator a foam of said reduced dye in leuco state and an inert gas while maintaining said dye in a leuco state, applying said foam with said applicator to at least one surface of said substrate, and exposing said applied foam to an oxidizing substrate to regenerate said dye and affix said dye to said textile substrate.  
   
   
       25 . A method of dyeing a cellulosic textile substrate according to  claim 24  wherein said purging fluid is an inert gas.  
   
   
       26 . A method of dyeing a cellulosic textile substrate according to  claim 24  wherein said purging fluid is reduced water.  
   
   
       27 . An apparatus for dyeing a cellulosic textile substrate with a dye in leuco state comprising: a container for containing a supply of reduced dye in a leuco state, said container substantially isolating said dye from oxidizing substances, a foam generator for generating a foam of said leuco state dye with an inert gas while maintaining said dye in said leuco state, a foam applicator for applying said foam to at least one surface of said substrate with the dye on said substrate being free for exposure to an oxidizing substance to regenerate said dye and affix said dye to said textile substrate.  
   
   
       28 . An apparatus for dyeing a cellulosic textile substrate according to  claim 27  characterized further by a cover for floating on said dye in said container, said cover covering substantially the entire surface of said dye in said container.  
   
   
       29 . An apparatus for dyeing a cellulosic textile substrate according to  claim 24  characterized further in that said container is a closed container isolating said contained dye from oxidizing substances.  
   
   
       30 . An apparatus for dyeing a cellulosic textile substrate according to  claim 26  characterized further by a cover in said container for floating on said dye in said container and covering substantially the entire surface of said dye in said container.  
   
   
       31 . An apparatus for dyeing a cellulosic textile substrate according to  claim 24  characterized further by a supply of inert gas connected to said container for supplying inert gas to said container as dye is delivered from said container to said generator.  
   
   
       32 . An apparatus for dyeing a cellulosic textile substrate according to  claim 24  characterized further in that said textile substrate is a traveling substrate and said applicator includes at least one nozzle extending across the traveling substrate for application of said foam to one surface of said traveling substrate.  
   
   
       33 . An apparatus for dyeing a cellulosic textile substrate according to  claim 29  characterized further in that said foam applicator includes a distribution chamber that uniformly distributes foam across the extent of said nozzle for uniform delivery of foam across said traveling substrate.  
   
   
       34 . An apparatus for dyeing a cellulosic textile substrate according to  claim 29  characterized further by another foam applicator for applying foam to the opposite surface of the traveling substrate.  
   
   
       35 . An apparatus for dyeing a cellulosic textile substrate according to  claim 31  characterized further in that said another foam applicator includes a distribution chamber that uniformly distributes foam across the extent of said nozzle for uniform delivery of foam to said traveling substrate.  
   
   
       36 . An apparatus for dyeing a cellulosic textile substrate according to  claim 27  and characterized further in that said apparatus is open exteriorly of said applicator for exposure of the foam applied to the substrate to the atmosphere for oxidation of the dye and affix said dye to said textile substrate.  
   
   
       37 . A dyed cellulosic textile product comprising: a denim fabric, a first dye having been applied in leuco state on one surface of said fabric and a different second dye on the opposite surface of said fabric.  
   
   
       38 . A dyed cellulosic textile product according to  claim 37  characterized further in that said first and second dyes have different characteristics.  
   
   
       39 . A dyed cellulosic textile product according to  claim 38  characterized further in that said different characteristics include differences in shade or color.  
   
   
       40 . A dyed cellulosic textile product according to  claim 37  characterized further in that said dye is an indigo dye.  
   
   
       41 . A dyed cellulosic textile product according to  claim 37  characterized further in that both said first and second dyes have been applied in a leuco state.  
   
   
       42 . A dyed cellulosic textile product according to  claim 38  characterized further in that both said first and second dyes are indigo dyes.