An ink jet ink composition includes one or two or more compounds A selected from the group consisting of a compound represented by Formula (1) and a compound represented by Formula (4), one or two or more compounds B selected from the group consisting of a compound represented by Formula (2), a compound represented by Formula (3), and a compound represented by Formula (5), and water,

##STR00001##

(in Formula (1) to Formula (5), R each independently represents NZ.sub.2 or OZ; R each independently represents a hydrogen atom, a sulfate group, or a sulfate; X each independently represents a hydroxyl group or a hydroxide salt; Y each independently represents a hydrogen atom, a hydroxyl group, or a hydroxide salt; and Z each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms).

The present invention relates to the use of reactive colourless and metal-free protein cross-linking agents for the cross-linking (tanning) of protein-containing substrates, said agents are environmentally friendly and give an improved fixation yield, a long-term cross-linking (tanning) stability and good washing off properties. The present invention further relates to processes for the cross-linking (tanning) of protein-containing substrates thereby creating an environmentally friendly process which minimizes the use of chemicals and further improves the quality and efficiency of the tanning and dyeing process. ##STR00001##

A method is disclosed for producing denim-effect garments by the following steps: 1) printing a reactive dye ink onto a PET film to form a pattern thereby obtaining a transfer printed PET film; 2) transfer printing a base pulp-treated fabric by attaching the transfer printed PET film thereby obtaining a denim-effect fabric; 3) cutting, sewing, washing to soften, and drying the denim-effect fabric and thereby obtaining a denim-effect garment. The method has the advantages of simple production, being environmentally friendly, having high efficiency, and being suitable for flexible fabrics, and the produced denim-effect garment of the invention has the advantages of having a good color fastness to rubbing, washing resistance, and having a diversity of patterns, and are suitable for large-scale production and application.

A reactive digital printing method can be performed with the following steps: 1) applying a primer to a fabric to be printed; (2) applying an ink containing a dye with multi-reactive groups to the fabric to be printed in step (1); (3) steaming and coloring, washing, dehydrating and shaping the fabric in step (2), to obtain a printed product. A related system with a combination of primer, a dye with multi-reactive group, printed fabric produced with the reactive digital printing method and items comprising the printed fabric can also be provided.