US2923592A

US2923592A - Processes of dyeing cellulosic materials with inorganic metallic compounds

Info

Publication number: US2923592A
Application number: US548234A
Authority: US
Inventors: Crosland Percy Field
Original assignee: Individual
Current assignee: Individual
Priority date: 1954-12-01
Filing date: 1955-11-21
Publication date: 1960-02-02
Anticipated expiration: 1977-02-02

Description

PROCESSES OF DYEING CELLULOSIC MATERIALS WITH INORGANIC METALLIC COMPOUNDS Percy Field Crosland, Bury, England No Drawing. Application November 21, 1955 Serial No. 548,234 Claims priority, application Great Britain December 1, 1954 2 Claims. (Cl. 8-52) This invention relates to an improved process for dyeing fabrics or yarns of cellulosic material with inorganic metallic compounds.

It is well known and is common practice to produce fast dyeings on piece goods made of cotton, flax and such synthetic fibers as are essentially cellulosic in nature such as viscose by impregnating the scoured material with a solution containing a suitable metallic salt or a mixture of such metallic salts, drying the fabric and then precipitating the hydroxides or basic salts of the metals in and on the fibres by treatment with alkalis or other solutions of sufficient basicity, the metal salts most frequently employed being the salts of iron and chromium and an admixture of them. The method above described produces the dye well known as mineral khaki.

It is also well known that if soluble iron salts are used alone in the process described above then yellow to brown shades, often described as iron buff, can be produced on cellulosic fibres.

It is known moreover, that the treatment of cellulosic fabrics by concentrated solutions of sodium or potassium hydroxides before the dyeing process, or in the course of it at the precipitating stage, or subsequent to it, substantially alters the shade and generally increases its depth.

In the following specification and claims the term inorganic iron salts is intended to cover not only an inorganic iron salt per se but also a mixture thereof with a further inorganic metal salt or salts and the term precipitated salt is intended to cover the hydroxide or basic salt or salts of the metal precipitated on or in the fibres.

It has now been found that if dry cloth dyed by any of the ways above described by impregnation with an inorganic iron salt and then precipitating the precipitated salt is heated to a high temperature for a short time the shade is deepened and made redder, the extent of the change depending upon the time of heating and on the temperature attained by the fabric and is the more striking as the proportion of iron salts used in any mixture of salts for the impregnation is increased.

An understanding of the invention will be obtained from the following examples, but it is to be understood that these are only illustrative and that the invention is not limited thereto.

Example 1 A well scoured cotton fabric is impregnated with a 15 percent solution of crystalline ferrous sulphate having the formula FeSO .7H O, is then well squeezed so that the pick-up of the liquor is about ninety percent of the weight of the dry cloth and is dried in hot air. A treatment of the material with a cold ten percent solution of sodium hydroxide precipitates either ferrous hydroxide or a basic ferrous sulphate or mixtures thereof on or in the fabric which, when washed and hung in air oxidizes to the ferric condition. This results in a brownish yellow shade but when the washed and dried cloth is heated to 145 C. for five minutes the shade is much deeper and redder.

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Example 2 If Example 1 is modified by using an excess of a solution of mercerising strength to precipitate the ferrous hydroxide or basic ferrous sulphates, the shade obtained will be richer and deeper than obtained in Example 1 and a subsequent heating of the washed and dried fabric to C. for five minutes will make the shade still deeper and redder.

Example 3 If instead of using. a ferrous sulphate solution as in Example 1 a solution of ferric chloride is used which is equivalent to the concentration of ferrous sulphate specified in Example 1 and is sufiiciently basic not to weaken the cloth when carefully dried, then by the alkaline treatment as given in Example 1, the ferric hydroxide or basic ferric sulphate is precipitated directly which avoids the need for oxidation. This results in a brown shade and if the fabric is washed, dried and subsequently heated to 165 C. for five minutes the shade is much deepened and reddened thereby.

Example 4 Cotton cloth is dyed by evenly impregnating it with a solution containing ten percent of hydrated ferrous sulphate and five percent of chromium sulphate having the formula Cr (SO.,) which has been made slightly basic. The fabric is then dried and subsequently the metallic compounds are precipitated by a hot solution of sodium hydroxide of 8% concentration, the resulting shade when washed, dried and heated to 135 C. for ten minutes is deepened and reddened.

In the specification of British Patent No. 730,601, there is described a process whereby the shade obtained is made deeper and redder in tone if a cellulosic fabric or yarn is impregnated with a solution of a ferrous salt and ferrous hydroxide or a basic ferrous salt precipitated by immersion in an alkaline solution and then the material is again impregnated and immersed in an alkaline solution. It is now found that if the material which has been coloured by the double treatment of impregnation, drying and precipitation, is heated for a few minutes at a temperature of between 130 C. and C. the colour is further deepened and reddened.

I claim:

1. In a process for obtaining deeper dye shades more nearly approaching red for cellulosic textile material which has been dyed by (1) impregnating said material with a solution containing an inorganic iron salt; (2) treating saidmaterial with an alkaline solution to precipitate at least one material selected from the group consisting of the basic salts and hydroxides of said inorganic iron salt; and (3) drying said material: the improvement which consists essentially in subjecting such dyed, dried material to a temperature of at least approximately 120 C., said temperature being insufiiciently high to damage the fibers of said material, for a sufficient period to permit the shade of the dyed material to attain the desired deepness of shade.

2. In the process defined in claim 1, the temperature to which said material is heated not exceeding about C.

References Cited in the file of this patent UNITED STATES PATENTS OTHER REFERENCES Schofield: Paint Manufi, June 1941, vol. 11, No. 6, pp. 181-184.

Claims

1. IN A PROCESS FOR OBTAINING DEEPER DYE SHADES MORE NEARLY APPROACHING RED FOR CELLULOSIC TEXTILE MATERIAL WHICH HAS BEEN DYED BY (1) IMPREGNATING SAID MATERIAL WITH A SOLUTION CONTAINING AN INORGANIC IRON SALT, (2) TREATING SAID MATERIAL WITH AN ALKALINE SOLUTION TO PRECIPITATE AT LEAST ONE MATERIAL SELECTED FROM THE GROUP CON SISTING OF THE BASIC SALTS AND HYDROXIDES OF SAID INORGANIC IRON SALT, AND (3) DRYING SAID MATERIAL: THE IMPROVEMENT WHICH CONSISTS ESSENTIALLY IN SUBJECTING SUCH DYED, DRIED MATERIAL TO A TEMPERATURE OF AT LEAST APPROXIMATELY 120*C., SAID TEMPERATURE BEING INSUFFICIENTLY HIGH TO DAMAGE THE FIBERS OF SAID MATERIAL, FOR A SUFFICIENT PERIOD TO PERMIT THE SHADE OF THE DYED MATERIAL TO ATTAIN THE DESIRED DEEPNESS OF SHADE.