US1905347A - Discharge printing and fabric produced thereby - Google Patents

Description

Patented Apr. 25,1933

cAMILL nEEYrUs, or New YORK, N. Y., nn GEORGE SCHNEIDER, 0F 'mon'rcmm,

s PATENToFFIc NEW JERSEY, LASSIGNORS CELANESE CORPORATION OF AMERICA, A CORPOBA TIQN OF'DELAWABE i DISCHARGE PRIM I NG AND FABRIC. PRODUCED .THEREBY No Drawing.

with dyestuffs that cannot be discharged by the ordinary methods now employed. I y

A further object. of our invention is to discharge-print fabrics by means of chro mate or dichromate in the presence of an acid. Further objects of our invention will appear from the following detailed description.

The production of designs on colored backgrounds,-on fabrics containing organic derivatives of cellulose, particularly :cellulose acetate, has heretofore offered serious difiiculties, since many of the dyes that color such fabrics cannot be discharged by the ordinary discharge methods that employ reducing agents such as hydrosulphites, formaldehyde-sulphoxylates etc. We have found that many of such dyestuffs may be discharged by the employment of a chromate or dichromate in the presence of an acid.

In accordance with our invention, we discharge print fabrics, and particularly fabrics containing yarns of organic derivatives of cellulose, which have been dyed with a suitable dye, whose color can be discharged by a dichromate or chromate in the presence of an acid. The paste that we employ for discharge printing contains a chromate or dichromate, and in order to effect the discharge 1 of the color, a substance containing an acid is applied to the fabric either before or after the application of the printing paste containing the dichromate or chromate.

\Vhile any fabric may be treated in accordance with out invention, it isparticularly applicable to the treatment of fabric containing yarnsof organic derivatives of cellulose, such as organic esters of cellulose and cellulose ethers. Examples of such organic esters of cellulose are cellulose acetate, cel- -App1icati6n filed May 6,1930. semi no. 450,309.

lulosejormate, cellulose propionateand cellulose butyrat'e,.while examples of cellulose ethers are ethyl cellulose, methyl cellulose and benzyl'cellulose. The fabric may consist wholly of yarns containing one or more organic deriva'tives'of cellulose, or it may be a mixed fabric containing yarns of organic derivatives of cellulose and yarns of other fibres. Examples of such mixed fabrics are mixed cellulose acetate and reconstituted cellulose, mixed cellulose acetate and cotton andmixed cellulose acetate and wool. I

paste is previously dyed or colored with any suitable dye whose color maybe discharged bythe oxidizing action of the chromate or dichromate in the presence of an acid. When thefabric contains yarns of organic deriva: tives of cellulose, it is preferably dyed. with dyes that are normally'insoluble in water, but which are dispersed or solubilized by a dispersing agent such as a sulpho fatty acid,

Thefabric to be treated with the discharg particularly sulpho ricinoleic acid (Turkey red oil). We have found that water insoluble colorin'gbodies of the anthraquinone series, or alkyl or other nuclear or N-substitution products thereof are particularly amenable.

to this process. However the fabric maybe dyed with other dyestuffs that are dischargeable by oxidation, and such dyestuffs may be of the di-or triarylmethane, thiazine, oxazine, azine, azo, xanthene and indigoid series.

The printing paste that is employed for obtaining the dlscharge Jprints contains a dichromate or chromate,.whi'ch ispreferably water soluble, such'as the chromate of sodium or potassium and the dichromate of sodium or potassium.

Inorder to effect good discharge, the presence of an acid is necessary. The acid may be employed in the formof a solution which is pre the discharge paste. However excellent reerably applied after the application of sults are also obtained when the acid is aps plied to the fabric before the application of the discharge paste. Any suitable acid may be used, examples of which are solutions of carboxylic acids such as citric acid, tartaric acid, acetic acid, benzoic acid, or even dilute aqueous solutions of mineralacids such as hydrochloric acid and sulfuric acid. The acid may be applied to the fabric by padding or in any other suitable manner.

Of the thickening agents that may be employed in making up the paste, it is preferable to employ such agents that are not appreciably affected by the chromates or dichromates. The following are suitable: gum tragacanth, tragasol, British gum or other dextrines, water soluble cellulose ethers, feculose (acetylated starch), agar agar, starches and mineral thickening agents or gelatinous masses, such as those produced by acidifying aqueous solutions of soluble silicates.

If color discharge prints are desired, there may be added to the printing paste, dyestuffs or pigments that are resistantto oxidation. These may be of the pigment type, mineral pigment type, vat dyes of the anthraquinone series which resist the action of oxidizing agents, or other suitable dyestuffs. Examples of such dyestuffs are Methylene blue (Color Index No. 922), Rhodamine 6G Extra (Color Index No. 752), or mineral pigments such as Chrome yellow, Lemon Chromeyellow, Guignets green and Vermillion. The vat dyestuffs of the anthraquinone series may be incorporated in the discharge paste in the form of esters of leuco compounds, while the mineral pigment colors may be applied in conjunction with albumen or the like.

In order further to illustrate our invention, but without beinglimitedthereto, the following specific example is given.

Example To a solution containing 190 parts ofpotassium dichromate in 1000parts of water, sufficient gum tragacanth thickening (30:1) or corn starchthickening is added to make a paste of required consistency.

After printing the fabric wlth a paste, the fabric has immediately applied thereto by padding or by pin rolls, a solution of oxalic acid or other acid of about 19% concentration, which may or may not have athickener I therein. The fabric is then run over dry ng' drums, and may then be aged for 10 to 15' minutes with steam at 5 lbs. pressure. The fabric may then be'glven if desired any sul) sequent hmshlng treatment, such as scouring, washing. etc. By the use of this process,

a fabric having a blue background with a discharge white design 18 produced.

It is to be understood that the foregoing 7 example is given merely by way of illustration, and that many variations may be made therein without departingfrom the spirit of our invention.

Having described our invention, what we desire to secure by Letters Patent is 1. Method of discharge printing a fabric containing organic derivatives of cellulose, which fabric has applied thereto an anthraquinone dye in the unreduced state, comprising locally applying thereto an oxidizing agent comprising a chromate and anacid.

2. Method of discharge printing a fabric containing cellulose acetate, which fabric has applied thereto an anthraquinone dye in the unreduced state, comprising locally applying containing cellulose acetate, which fabric has applied thereto an anthraquinone dye in the unreduced state, comprising locally applying thereto a acid.

In testimony whereof, we have hereunto subscribed our names. 1

(AMILLE DREYFUS. GEORGE SCHNEIDER.

chromate and thenapplying an