Dyeing Method for Control of Multicolored Pattern Nylon Carpet

This invention relates to a method to dye, by printing or the like, carpets to produce multicolor patterns.

In print dyeing of textiles to patterns with rotary screens, flat bed screens, Stalwart, controlled spray, TAK dyeing and the like, it is known to use reducing agents to resist dyeing or discharge dyed fabric. This resistor discharge printing is a two-step dye, dry, discharge process. Color discharges can be made by combining a dye stable to the reducing agent with the reducing agent.

For carpets, and nylon carpet in particular, differential coloration can be achieved in several ways, each resulting in variations. A common method is to apply dyestuffs on localized areas of the carpet by some form of printing then to flood the entire area with another dye. In this way, the localized color is covered over and the in-between areas are colored with the flood dye for a 100 percent coverage. The resulting color, when the flood color is superimposed on to the base color, is the composite of both colors and the outcome color is solid with only tonal variations of the two solid colors.

This invention is an improvement in a method of dyeing nylon carpet in a pattern. The improvement comprises a continuous, wet-on-wet process of adding a reducing agent selected from the group consisting of zinc formaldehyde sulfoxylate, sodium formaldehyde sulfoxylate mixtures thereof and thiourea dioxide with a dye selected from a group consisting of acid, direct, dispersed, fiber reactive and mixtures thereof. Also, an activator for the reducing agent and optionally a stabilizer for the dye bath is added. Then the dyed carpet is steamed, without drying, to activate the reducing agent to make a dyed pattern that is reproducible, and has controlled, differential multicolorations. Each of the dyes is selected for its known characteristic behavior with the activated reducing agent, whether it is completely unaffected, partially affected or completely destroyed. Each dye is applied at a time during the dyeing so that its characteristic effect produces the desired multicoloration effect. The preferred reducing agent is zinc formaldehyde sulfoxylate or thiourea dioxide. The activator for the reducing agent can be a salt, either acid or alkaline. The preferred activator is ammonium sulfate. The preferred stabilizers for the dye bath are the alkali metal salts of a sulfonated naphthalene condensate; more preferably, the sodium salt. The preferred amount of the reducing agent is about 5 to about 15 grams per liter of the liquid dye paste. The preferred amount of activator is about 2 to 10 grams per liter of the liquid dye paste. The preferred amount of the stabilizer is from about one-half to about 5 grams per liter of the liquid dye paste. The steaming should take place at about 100.degree. C. for about 4 to 10 minutes. Reducing agent can be added with the print paste, with the flooding bath, with the TAK drops or in any two or all three of them. The carpet may be printed by the rotary screen method, the flat bed screen method, ColorFlo or Stalwart method and/or controlled spray method. Additional material may be added to any one of the dye formulations such as thickener, surfactant, sequesterant, or mixtures thereof. A tufted carpet dyed by this method will have each tuft with differential multicolorations along its length.

This invention results in a multicolor appearance and sometimes an iridescence which is formed by the interplay of the dyestuffs according to the effect of the added chemicals to the print paste, the flooding dyebath, and/or TAK drops.

This invention calls for the regular printing procedure but with the addition of zinc formaldehyde sulfoxylate or other reducing agent and ammonium sulfate or other activator. By the irregular but consistent behavior of the reducing power of the zinc formaldehyde sulfoxylate activated by the acid which is liberated by the ammonium sulfate during steaming, a nonuniform coloration and interplay of color results producing an unique multicolor effect.

A necessary aspect of this invention is the proper selection of dyestuffs and these are categorized according to whether they are (a) completely unaffected, (b) partially affected or (c) completely destroyed by the action of the reducing agent.

A search of the dyestuffs on the market of the four major classes of dyes used for nylon--acid, direct, disperse and fiber reactive, has produced a sufficient number which are applicable concomitant with the normal fastness requirements.

This chemical mechanism of this invention can be utilized in several ways:

(a) By including the reducing agent in the paste by all the known methods of printing. This paste could include dischargeable, partially dischargeable and/or nondischargeable dye from any of the mentioned classes; then flood nondischargeable dyes.

(b) By including the reducing agent in the flooding bath with dischargeable, partially dischargeable and/or nondischargeable dyes over a print area which contains nondischargeable dyes.

(c) By including the reducing agent in both print paste and flooding bath using all the types of aforementioned dyes.

(d) By including the reducing agent in the TAK drops when TAK printing a dyed or printed carpet.

TAK printing is a method to mechanically position drops of dye on a carpet to be dyed as described in U.S. Pat. No. 4,127,014, column 1, hereby incorporated by reference in toto and more fully in a paper by Ferdinand Leifeld of Edward Kusters Machinefabrik, Krefeld, Germany, called Multi-TAK--A Variable Pattern System for Carpet, presented at the 1976 International Technical Conference of AATCC, October 13-15, Montreal, Quebec, Canada, and available from AATCC in printed form, P.O. Box 12215, Research Triangle Park, N.C. 27709. TAK is a trademark of E. Kuster of Germany.

In another example thiourea dioxide was added, as above, in place of Paralite (ZFS) and very similar results, as described herein, were obtained.

Following are procedures for including the reducing agent, thiourea dioxide or zinc formaldehyde sulfoxylate (ZFS) in the print paste, Kuster flood and TAK drops. Additionally, the thiourea dioxide or ZFS could be added in any two or all three of the applications of dye to carpet.

The above procedures are duplicated adding thiourea dioxide in place of ZFS to get the same results described herein.

The dyeing process of this invention is distinguished from prior art methods. This process is the first to achieve a wet-on-wet, continuous process to create variations of color in depth in a carpet. That is, this use of the specific activated reducing agents produces variations of color along the length of each tuft of yarn in the carpet. The reducing agent, such as ZFS, affects dyes in the dye base (bath, paste or the like) differentially, but reproducibly and predictably from the dyes selected, causing multicolorations, color separation and even sometimes colors not introduced to the dye base by the chemical interaction during steaming which activates the reducing agent. Previous methods were able to produce only two colors, not the multicolors of this invention, because the previous discharge method, dye, dry, discharge printing can only discharge to white on a color background or color discharge on another color background resulting in two colors with tonal variations.