US2342642A - Method of coloring textiles with pigments - Google Patents

Description

Patented Feb. 29,1944

METHOD OF COLORING TEXTILES WITH ",IIGMENTS Norman S. Cassel, Ridgewood, N. J., assignor to Interchemical Corporation, New York, N. Y., a

corporation of Ohio No Drawing. Application August 3, 1940, Serial No. 351,204

2 Claims.

This invention relates to the dyeing of textile fabrics, and has particular reference to a new and novel method of dyeing fabrics with pigment, characterized by the metered application of carefully controlled amounts of pigmented lacquer emulsions to the fabric.

Textile fabrics are almost universally colored by being treated with a solution of a dyestufi in an aqueous medium; the soluble dyestuff is precipitated in the capillaries of the fibers of the yarns, or is caused to adhere chemically to the textile material. In some cases, water-insoluble dyestuffs having an affinity for certain synthetic fabrics are used in solution in other solvents. Since all of these dyestuffs must be capable of conversion from the soluble state to the insoluble state in contact with the fiber, and since they must be resistant to a great variety of deteriorating influences, the problem of inexpensive, fast textile colors has always been a pressing one.

The ready availability and low cost of the insoluble pigment colors has prompted many investigators to study the application of these colors for the dyeing of textiles, but with relatively little success. Except where the pigment is incorporated into a spinning solution used for making synthetic fibers, unaided mechanical adhesion of the pigment to the yarns has proven unsuccessful. Attempts to cause the pigment to adhere to the fabric by the use of binders hav likewise proven abortive, for a variety of reasons. A principal cause has been the failure of the pigment binders to withstand the severe conditions to which textiles are subjected; the failure of the binder leaves the pigment in mere mechanical contact with the fabric, whence it is easily removed. A second important difficulty has been that of even application of very small quantities of pigment plus binder, so that the fabric is colored uniformly. The problem is presented by the tendency of pigments to flocculate or settle out in highly'disperse media, so that uniform application is very difficult.

It has been proposed to dye textile fabrics with pigmented lacquers emulsified as the discontinuous phase of a lacquer-in-water emulsion, using heat-convertible synthetic resins as binder in the lacquer. Such emulsions give satisfactory uniform dyeings on fabrics, when the fabrics are immersed in the bath and the excess color squeezed off. However, the cloth must be heated after the dyeing operation, both to evaporate the water and solvent, and to set th resin. If the fabric is not maintained in a uniform state of tension, or if e d y i d e unevenly, the color will tend to migrate and give a streaked appearance. This tendency is considerably aggravated as cloth thickness increases, so that shirting broadcloths and heavier fabrics must be handled with special equipment and with such extreme care that rapid drying is impossible. As a result, the emulsion pad dyeing has for the most part been restricted to rather thin fabrics, or to special cases with heavier fabrics.

I have discovered that cloth may be dyed with emulsions of pigmented lacquers in water, while substantially eliminating the tendency of the lacquer to migrate, by applying a very thin emulsion to the cloth in sufiicient quantity to thoroughly permeate the cloth, while limiting the amount of material to about one-half of What the cloth will absorb from a bath and retain after being wrung out under substantial pressure. Since most cotton and rayon cloths retain about equal weights of liquid under such treatment, this limit may be more simply stated as a fraction of cloth weight.

The dye liquid may be applied to the cloth by forming a thin film on a roll coating machine, and then transferring it to the cloth; but I prefer to use a uniformly knurled cylinder wiped with a doctor blade, since the amount of liquid applied can be most easily controlled by this method, and the application is far more uniform than with a roll coater.

I believe that migration is avoided by this process because of the fact that no liquid water is present on the fabric during the drying operation, the fabric having absorbed the water.

Typical examples of my invention are the following:

' EXAMPLE 1 Clear emulsion Parts by weight Solvent soluble urea-formaldehyde resin solution (50 resin, 30 butanol, 20 xylene) 5.0 Alkyd resin solution (50 resin, 50 pine oil) 15.0 Pine oil 2.5 Solvesso #2 (hydrogenated petroleum naphthat-boiling range l35177 C.) 27.5 are emulsified by adding slowly, with stir- Sodium lauryl sulfate 2.5 Water 47.5

to produce a stable emulsion containing 10% resin solids. The alkyd resin is a 33% soya oil modified glycerol phthalate, acid number about 5.0.

EXAMPLE 2 Yellow emulsion Parts by weight A 20% aqueous pulp of yellow pigment, prepared by diazotizing dichlorbenzidine and coupling with acetoacetanilide- 6.5 A 35% aqueous solution of sulfonated tannin .25 are stirred together on a high speed mixer, and added to a mixture of' Alkyd resin solution of Example 1 8.5 Pine nil 10.0 I

The resultant water-in-lacquer emulsion is diluted with- Parts by weight Solvesso 48.0

and added slowly, on a high speed mixer, to

a solution of- Sodium lauryl sulfate 2.0 Water 24.75

The emulsion inverts as it enters the water, producing a stable lacquer-in-water emulsion having 1.3% pigment solids, and 5.5% resin solids. This is preferably mixed with four parts of water and one part of the clear emulsion of Example 1, before using. The resultant dyeing solution then carries a maximum of .21% pigment and 2.6% resin solids.

When used in normal fashion, this emulsion migrates badly on drying. When applied by an intaglio plate or roll coating method, so that from 40 to 50% of the cloth weight is absorbed, uniform non-migrating dyeings are obtained.

EXAMPLE 3 .4220 blue Parts by weight 20% aqueous pulp of blue pigment formed by diazotizin dianisidine, and coupling it with the sodium salt of the ortho toluidide of beta oxy naphthoic acid (Naphthol This lacquer-in-water emulsion contains 1.1

pigment solids and 4.1 resin solids. On minimum dilution with 4 parts of water and 1 part of clear, the pigment solids of the dyebath is 1.8, and the resin solids 2.3%. Like Example 2, it produces a migrating color by ordinary means, but a satisfactory job when applied by gravure methods.

While I have disclosed but a few examples of dyeing emulsions, the example can be multiplied indefinitely without departing from the scope of my invention. Where resistance to washing and dry cleaning are not important, substantially any pigments or binders may be used, provided care is taken to maintain th conditions necessary for appearance and hand. Where qualit dyeing is desired, however, the pigments and binders must be so chosen as to resist dry cleaning solvents and washing. As indicated above, best results are obtained with the carbamide formaldehyde resins, including the resins made from formaldehyde and urea, thiourea, melamine, and other urea derivatives and substituted ureas. Phenol formaldehyde resins, and other resins which can be set rapidly at elevated temperatures, may also be used, although the results obtained with them are not as satisfactory as those obtained with the carbamide formaldehyde resins,

Any emulsifying agent can be used to prepare the emulsions, provided it makes a stable emulsion with the particular lacquer. I have successfully used Lamepon A (protein composition products condensed with fatty acids), Santomerse D (sodium salts of alkyl substituted aryl sulfonates), various sodium alkyl sulfates, and others, as well as those shown in the examples.

The term lacquer, as used in the claims, refers to solutions, in volatile organic solvents, of filmforming binders or thickeners which are waterinsoluble, and which are plastic or solid, so that when the solvent evaporates, the binder forms a film which is substantially set where deposited.

I claim:

1. The method of pigment dyeing textile while avoiding migration of color on drying, which comprises applying to a textile fabric a thin pig mented lacquer-in-water emulsion whose wet weight is not in excess of of fabric weight, evenly distributing the emulsion through the fabric by pressure, and drying the fabric.

2. The method of pigment dyeing textiles while avoiding migration of color on drying, which comprises simultaneously applying to a textile fabric a thin pigmented lacquer-in-water emulsion whose wet weight is not in excess of 50% Of fabrlc weight and evenly distributing the emulsion through the fabric by pressure, and thereafter drying the fabric.

NORMAN S. CASSEL.