Denim fabric with fire-retardant properties and process of dyeing the warp with indigo blue dye

Abstract

This invention relates to a Denim protective fabric, with fire-retardant properties, and the process of dyeing the warp with indigo blue dye on a mixture of cellulosic and synthetic fibers, in order to obtain a permanently fire-retardant fabric, resistant to flame, heat, breaking, tearing, cutting and abrasion by impact. The resulting fabric is also antistatic and can be considered as a protective fabric like fire-retardant Denim and also a multi-risk fabric. The indigo blue dye is applied on a mixture of cellulosic and synthetic fibers with permanently fire-retardant properties such as fire-retardant viscose, fire-retardant modal, modacrylic, polyacrylate, polyamide, polyester, antistatic carbon, para-aramid, meta-aramid, polyamide-imide, polyethylene, PBI, with the aim of obtaining an authentic Denim jeans fabric, with the characteristics of the tincture based on indigo blue dye that loses its color on rubbing, with use and washing.

Claims

1. A process of dyeing the warp yarns of a denim fabric with indigo blue dyes, the warp yarns having a mixture of permanently fire-retardant fibres that contain natural, cellulosic and synthetic fibres, wherein the dyeing is performed continuously in a dyeing indigo machine and the fire-retardant fibres have intrinsic fire-retardant properties, comprising the following steps in order: in a preparation phase: preparing the warp yarns by applying a first dye in the form of reduced indigo blue dye to the warp yarns to obtain pigmentation of the synthetic fibres; oxidizing the warp yarns by subjecting them to air to oxidize the dye on the cellulosic fibres and to convert the reduced dye deposited on the synthetic fibres into a pigmented form, fixing the first dye on the synthetic fibres by cationization with quaternary amines, and washing the warp yarns to remove dye that is not fixed on the synthetic fibres; in a dyeing phase: applying reduced indigo dye to the warp yarns to obtain pigmentation of the synthetic fibres; and oxidizing the warp yarns by subjecting them to air to oxidize the dye on the cellulosic fibres and to convert the reduced dye deposited on the synthetic fibres into a pigmented form, wherein the dyeing phase is repeated in consecutive cycles; in a finishing phase: binding the dye on the synthetic fibres via application of a cationic polymer; drying the warp yarns, polymerizing the cationic polymer with the indigo dye on the synthetic fibres to achieve an integration of the indigo dye on the structure of the synthetic fibres; and in a gluing phase: applying vinyl copolymers to the warp yarns, and drying the warp yarns to fix the vinyl copolymers on the warp threads.

2. The process according to claim 1, wherein the reduced indigo blue dye is mixed with anionic surfactants and other dyes to obtain dyeing of the yarns by transformation of the indigo dye after oxidation.

3. The process according to claim 1, wherein the indigo blue dye is reduced with sodium dithionite and caustic soda.

4. The process according to claim 1, wherein the steps of applying the dye are undertaken in an inert atmosphere created with a nitrogen generator.

5. The process according to claim 1, wherein the dyeing phase is performed in consecutive cycles that obtain concentric rings of indigo dye tincture on the yarn.

6. The process according to claim 1, wherein the dyeing phase is repeated until the fibers contain between 1.5% and 2.7% by weight of indigo dye after the finishing phase is completed.

Description

DESCRIPTION OF THE FIGURES

(1) To complement the description below and with the aim of helping to reach a better understanding of the characteristics of the invention, this document is accompanied by a set of FIGS. that form an integral part of the document and can be used to understand specific features of the novelty of the invention, and these FIGS. show the following:

(2) FIG. 1. Shows a schema of the traditional dyeing process of a synthetic fibre with dyes related to these materials that are applied to the fabrics.

(3) FIG. 2. Shows the tincture applied according to the invention.

(4) FIG. 3. Shows a cross section of a cotton yarn dyed with indigo dyes viewed under a microscope, all performed in accordance with the object of the invention.

PREFERRED EMBODIMENT OF THE INVENTION

(5) As described above, FIG. 1 shows traditional dyeing of a synthetic fibre with dyes that are similar to such materials, while FIG. 2 shows tincture applied according to the invention, forming concentric rings (1), or in other words, superficial layers, leaving the central nucleus (2), that is the core of the yarn, without dye, because the dye does not penetrate to the nucleus of the yarn.

(6) Finally, FIG. 3 shows a cross section of a cotton yarn (3) that has been dyed with indigo dyes, in accordance with the Denim dyeing process shown in FIG. 2, viewed through a microscope.