The following phenomena occur when woven cloth which is with dyed yarn and undyed yarn, such as denim cloth or the like, is subjected to desizing, enzymatic weight reducing treatment or the like processing.
When desizing is carried out, a desorbed dye redeposits to the bleached yarn to cause staining of the white area. When enzymatic weight reducing treatment is carried out, a desorbed dye redeposits not only to the bleached yarn to cause staining of the white area but also to the stripped area (white area) of the top-dyed yarn, thus reducing quality of the product considerably.
There is a treatment in which its garments dyed with not only the indigo denim dye but also other dyes are washed using a washer with the joint use of pumice, enzymes and the like to create a washed out and faded also worn-out feeling, and such a treatment also causes redeposition of desorbed dyes and reduction of the quality.
With the aim of preventing the staining of white areas and redeposition of dyes, a number of materials have been developed but with no success in resolving the above problems.
For example, CMC (carboxymethylcellulose) sodium, poval, polyvinyl pyrrolidone and the like have been known from old times. Examples of such materials so far disclosed in patents include calcium chloride (JP-A 46-330; the term "JP-A" as used herein means an "unexamined published Japanese patent application"), sodium polyacrylate (JP-A 48-64283), nonionic type surface active agent (JP-A 50-18786), mixture of .beta.-naphthol and ethylene oxide (JP-A 55-22081), .alpha.-olefin sulfonate (JP-A 56-53274), water soluble high polymer whose carboxyl groups are partially or entirely made into salt (JP-A 56-63081), copolymer of maleic anhydride with isoamylene and/or amylene (JP-A 58-41981), specified organosilane and organosiloxane (JP-A 58-70774), specified aromatic sulfonic acid condensate and oil (JP-A 60-45676), a water soluble copolymer containing unsaturated carboxylic acids and a formalin condensate of a specified polycyclic aromatic compound sulfonate (JP-A 61-215769), a vinyl polymer having a pyrrolidone skeleton or a copolymer of vinyl pyrrolidone with other monomer (JP-B 5-61395; the term "JP-B" as used herein means an "examined Japanese patent publication"), specified diquaternary ammonium salt and mono-, poly-quaternary or specified polymer-ammonium salt or unquaternarized basic nitrogen-containing polycondensates (JP-A 62-117887), organic sulfonic acid and/or its salts (JP-A 63-135581), synthetic detergent active component, vinyl pyrrolidone polymer and nonionic cellulose ester (JP-A 63-37200), significantly insoluble trapping agent (JP-W 63-502761; the term "JP-W" as used herein means an "unexamined published Japanese international patent application"), cationic cellulose (JP-A 1-201588), polyalkylene oxide-based graft polymer (JP-A 63-260994), water soluble salts of polymerized fatty acids (JP-A 1-272888), specified water soluble polymers (JP-A 1-185398) and the like. In addition, a method in which the prevention is effected by controlling the treatment conditions and a method in which redeposition of dyes and stains is reduced by processing the surface of fabrics have also been developed.
However, when mediums such as surface active agents and the like are used as one of such prior art findings, they cause environmental problems such as water pollution and the like, or a mixture of a desorbed dye and a surface active agent redeposits to fabrics in some cases. The invention in which canonized cellulose is used (JP-A 01-201588) contemplates overcoming such problems but is highly costly, because it is necessary to cationize cellulose at a ratio of 100 to 3,000 milli equivalent/kg fabric.
Also, when the dye of interest is anionic and disperse type, it is necessary to anionize with an anionic dispersing agent. More disadvantageously, when an enzyme is present in the washing, the enzyme itself becomes anion under general washing conditions and therefore is electrically adsorbed by cationic cellulose, thus entailing reduction of its effect.
On the other hand, an attempt has been made to use an insoluble adsorbent for pigments and/or fat soils but on condition that washing should be effected under application of ultrasonic wave (JP-W 63-502761). Since this method is also characterized by the cationization treatment of polyquaternary ammonium compounds and the like, it has problems similar to the case of the aforementioned catonized cellulose. In addition, though there is a case in which effects of a nonionic cellulose ester are found by the combined use of other mediums (JP-A 63-37200), carboxymethylcellulose as a representative of the cellulose ester itself is already known in the art and the method has a problem similar to the case of the aforementioned canionized cellulose in terms of the necessity to carry out etherification.