Mitsui Toatsu Chemicals, Incorporated

Tetsuo Sakagawa

Hitoshi Koshida

Takayuki Nakayama

Hiroshi Suwa

Masao Imai

Akio Karasawa

Akitoshi Igata

Denim cotton warp yarns are rope-dyed with a benzoquinone dye of formula (I): ##STR1## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.1 ', R.sub.2 ' and R.sub.3 ' commonly or independently represent a hydrogen atom, a halogen atom, alkyl, cycloalkyl, alkenyl, aryl, aralkyl, alkoxyl or alkoxyalkyl alone or in combination with a red .DELTA..sup.2,3' -biindolin-3,2'-dione dye and/or a blue indigoid dye or sequentially with the latter dye.

Benzoquinone dye, rope-dyeing dye compositions, cotton rope-dyeing

Disclosed is a dyeing process for rope dyeing denim cotton yarns a fashion blue color which comprises the steps of forming the yarns into a rope; repeatedly immersing the rope in a dye bath containing a reduced water soluble form of a halogenated indigo derivative which is air oxidizable, squeezing the rope to remove dye bath liquid therefrom exposing the damp rope air to air oxidize the reduced form of the indigo derivative in the yarn; and then further oxidizing the incompletely oxidized reduced form of the indigo derivative in the yarn forming the rope in an oxidizing bath containing a chemical oxidant, e.g., sodium perborate.

Rope dyeing process using halogen indigo derivative and dyed article

Dyed denim cotton yarns capable of meeting the market demand for color jeans can be provided by immersing denim cotton yarns in a dye bath containing a dye or dye composition comprising a specific indirubin derivative(s), a specific quinophthalone derivative(s) and/or an indigo dye, squeezing and air-oxidizing the dyed yarns, and repeating a series of these steps.

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Nishinomiya, Japan

Tetsuo Sakagawa