US807453A - Indigo dye. - Google Patents

Description

UNITED STATES PATENT onnion.

INDIGO DYE.

Specification of Letters Patent.

Patented Dec. 19, 1905.

Application filed October 12, 1904. Serial No. 228,196.

To all whom it may concern:

Be it known that I, JOHN W. Fruits, of Winston Salem, county of Forsyth, State of North Carolina, have invented an Improvement in Indigo Dyes, of which the following is a specification.

My invention has reference to indigo dyes, and consists of certain improvements, which are fully set forth in the following specification.

In another application, Serial No. 227,098, and filed October 4:, 1904, I have described a method of dyeing textile material with reduced indigo dyes and in connection therewith have specified the mixture of indigo dye forming the subject-matter of this application.

Heretofore the results with indigo in the art of dyeing have been, if applied to cotton yarn or fabrics in a strong or concentrated reduced solution and then oxidized by exposure to the air or otherwise, the indigo is oxidized on the fiber superficially, and hence crooks badly and scours badly. If the dyeing is done by repeated dips in a dilute reduced solution or a succession of comparatively dilute solutions, the result is much better as to fastness to rubbing and scouring; but it is impossible to exhaust an ordinary indigo-vat entirely, and if the weak indigo solution be run off there is considerable waste. Further, very serious practical difficulties are experienced in the effort to feed indigo, so as to keep up a standing vat. This is due to the fact that the reduced solution of indigo and the chemicals used for reduction are so unstable and are spontaneously decomposed, and, further, because the bath becomes saturated by these chemicalse. c with the salts of iron or lime, zinc, and soda.

I have found it advantageous to apply to the dry yarn or fabric a reduced solution of indigo of such strength as is proportionate to the shade required by giving only one or two dips in this solution and expressing the surplus dye by squeeze-rollers, an operation familiarly known as padding. For a full shade I prefer to use a padding liquor containing, for example, twenty pounds of indigo paste of twenty per cent. strength, or four pounds of indigo-powder; twelve pounds of unslaked lime,which is to be slaked in sufficient water and the milk of lime used; four pounds zinc-dust; two pounds caustic soda, solid or granulated; two pounds starch, and two pounds alizarin-oil, seventy-five per cent, the whole made up to twelve and onequickness, and ease of manipulation.

half gallons with water of preferably 120 to 140 Fahrenheit. In the preferred form of my composition I employ a mixture of the dry indigo-powder, zinc-dust, caustic soda, sifted lime, and starch, substantially in the proportions specified, which may be sold as a commercial compound and mixed with water for use. A solution thus compounded will be found to go on or penetrate the fiber well; but if exposed to the air, or if immersed in clear water, or in many solutions the indigo is oxidized on the fiber superficially. I convey the padded yarn directly from the squeeze-rolls of this padding liquor into a compartment containingasolution which will prevent this oxidation, and there the indigo is fixed upon or worked into the fiber, and the result is a color much brighter and faster than can be obtained without this treatment. Adilute solution of hydrosulfite of soda is efiicient for this operation, or a solution of sodium sulfid may be used, which is still cheaper and easier of application. Other solutions having a reducing action or which will prevent the oxidation of the indigo during this operation may be substituted. After giving the yarn or fabric the desired number of dips in this solution and passing through the proper squeeze-rolls the material is passed over reels in the air to oxidize the indigo. It may then be rinsed or soaped, if desired, and dried. All these operations are preferably done in one continuous succession on machines of simple construction.

While there are well-known ways of reducing indigo other than with zinc-dust and lime, I consider this the best because of cheapness,

Moreover, it appears to be the only manner of reducing indigowhich admits of the ingredients being mixed together dry, if the alizarinoil be left out; but in this case about four pounds of dry indigo-powder should be used instead of the twenty pounds of paste, as stated in the formula.

Synthetic indigo is made .in a dry powder; but it is almost universally used in the paste form, and it is recommended in this form by the manufacturers, because, as they say, the powder needs to be ground into a paste with water before it can be properly used in making up an indigo-vat. The practical reason for this is that the dry powder is somewhat hard to mix with water in such fine subdivision and suspension in the water as to get thorough reduction; but I have found experimentally that if it be intimately mixed with the other ingredients, especially the starch, there is no difficulty in holding them all in suspension in the water with complete and rapid reduction of the indigo. As far as I am aware this use of starch is new and original, and I have introduced it for the double purpose of giving body to the solution to hold the other bodies in suspension until the indigo is reduced and also beis also to be understood that my invention includes the use of the indigo either as a powder or as a paste, as may be desired.

Having now described my invention, what I claim as new, and desire to secure by Letters Patent, is-

1. A padding liquor for indigo dyeing which consists of a mixture of indigo, milk of lime, zinc-dust, caustic soda, and starch, when mixed with a solvent.

2. A padding liquor for indigo dyeing which consists of a mixture of indigo, milk of lime, zinc-dust, caustic soda, starch, and alizarin ,oil, when mixed with water to form a solution.

In testimony of which invention I have hereunto set my hand.

JOHN W. FRIES.

Witnesses: 7

(bus. A. WATSON, BERNARD J. PFOLEL.