3,343,905 United States Patent Office Patented Sept. 26, 1967 2 their washing fastness improved to acceptable levels. 3,343,905 After-treatments of this sort are objectionable from the NYLON DYES Standpoint of both time and cost, but, until now have been James F. Feeman, Wyomissing, Pa., assignor to Crompton the best means available to the dyer for the production of & Knowles Corporation, Worcester, Mass., a corporar Washfast heavy dyeings on nylon. tion of Massacialsetts Other classes of dyes applicable to nylon are similarly No Drawing. Fied Oct. 20, 1966, Ser. No. 587,987 unsuited to production of washfast heavy dyeings. Dis 3 Claims. (C. 8-26) perse dyes are notoriously poor to washing fastness, even This application discloses and claims subject matter though they produce level dyeings with ease and of satis contained in my copending applications, Ser. No. 328,051, O factory depth. Their washfastness is not improved by filed Dec. 4, 1963, now Patent No. 3,305,539 and Ser. after-treatments to the same extent that is found with the No. 378,460, filed June 26, 1964, now abandoned. neutral dyeing acid dyes. Mordant dyes may be metallized This invention relates to dyes for nylon fibers, to a (notably chromed) on nylon by after-treatments with method of dyeing nylon fibers and to the products pro metal salts in acidic baths yielding dyeings of excellent duced by such process. fastness to washing, but the dyeing procedure is very dif Dyeing of nylon in heavy depths of shade with a high ficult to control to the degree necessary to enable the order of fastness to washing is an important technical matching of shades. Therefore, mordant dyes are used problem which has not been solved previously in a satis in only very specialized applications where time is no factory manner. problem. Reactive dyes have thus far failed to produce Many available dyes which are applicable to nylon have 20 the desired very heavy dyeings required; presumably, this failed to produce desirable results with respect to Washing is due to the relatively low number of amino end groups fastness of deep shades. The so-called acid dyes (see The available in the nylon fiber and which are necessary for Colour Index-Second Edition or the Annual Technical attachment of the dye molecule to the fiber. Manuals of the American Assocition of Textile Chemists Accordingly, it is one of the objects of this invention to & Colorists) as a class have been used extensively for 25 provide a new group of dyes for nylon that will have an nylon dyeing. However, those acid dyes which require unique combination of properties in that they can be ap large quantities of strong mineral acid to completely ex plied in deep (heavy) shades that are highly washfast and haust the dye from the bath are not used for dyeing nylon to do So without the necessity of resorting to after-treat because the acid degrades the fiber. In general, the acid ments with conventional fastening agents. dyes which are not used for nylon have two or more solu 30 Another object of this invention is to provide techniques bilizing groups in the dye structure. As used hereinafter, for dyeing nylon fibers with acid nylon dyes in from light the term "acid nylon dyes' will refer to those acid dyes to deep shades and at the same time, to obtain highly which do not require the use of strong mineral acid to Washfast dyeings even in the heavy shades without the exhaust onto the fiber and which, therefore, are exten necessity of after-treating the dyeings with conventional sively used to dye nylon. 35 fastening agents, The acid nylon dyes give reasonably good results when Still another object of this invention is to provide an used in light to medium percentages provided dyebath unique textile product i.e., nylon textiles dyed with acid additives are used to control levelness and exhaustion rate nylon dyes in deep shades that are highly washfast. of the dyes. However, in the high percentages necessary Other objects and advantages will appear in the de to provide deep shades, the acid nylon dyes are lacking Scription of the invention. in either “pile-on' capability (i.e., will not exhaust prop According to this invention, I have now discovered erly onto the fiber to the extent necessary to give the de that Surprising excellent washfastness is obtained even sired depth of shade) or in washing fastness. when dyeing nylon in heavy shades by employing dye Acid dyeing acid dyes (i.e., those requiring acetic or compositions comprising at least one non-metallized, non formic acid to exhaust well from the dyebath) suffer from metallizable neutral dyeing acid nylon dye and at least lack of “pile-on' capability, and, while they are satisfac a molecular equivalent of a premetallized azo 1:1 dye: tory with respect to staining other fibers during washing, chromium complex which is readily soluble in neutral and dyeings made therewith lose color to the wash liquor dur Weakly alkaline solutions. In dyeing with such dye com ing laundering procedures. positions, the color will build up at such a rate that the Water soluble premetallized acid dyes (e.g., complexes . 50 dyer has control of the exhaustion of dye and a full range having a 1:1 dye: metal ratio and solubilized by means of of shades ranging from light to heavy depths can be ob substituent sulfonic or carboxylic groups) "pile-on' tained. Apparently, the non-metallized dye penetrates the poorly, but have excellent washing fastness. The corre nylon fiber first, preferably from a neutral bath, and is sponding water soluble 2:1 dye: metal complexes have fixed there by the pre-metallized complex which is dyed poor "pile-on' capability and they exhibit poorer wash 55 on Subsequently in the presence of acid and at elevated fastness than the corresponding solubilized 1:1 dye: metal temperatures. complexes. Suitable pre-metalized azo 1:1 dye-chromium com The neutral dyeing 2:1 premetalized acid dyes (com plexes for use in accordance with this invention include plexes having a 2:1 dye: metal ratio but free from Sub those which are substantially free of dye-metal complexes stituent sulfonic or carboxylic acid groups) exhaust well 60 in which the dye-metal ratio is 2:1 and which are also giving heavy shades, but the resultant dyeings do not meet substantially free of unchromed dye. However, in order high standards with regard to washing fastness. These for the pre-metallized azo 1:1 dye-chromium complex to dyes additionally have limited water solubility which pre be useful for purposes of this invention, it must have cludes their use in certain important types of dyeing ma sufficient solubility-preferably imparted by including one chinery which employ low liquor ratios. 65 Sulfonic group in the dye structure-so that it will dis Neutral dyeing acid dyes have been and are now being Solve readily in neutral or weakly alkaline solutions and used extensively for the production of heavy shades on dye onto nylon fibers from solutions having a pH of about nylon fibers because of their ease of application, their ex 4 at elevated temperatures of the order of 90-125 C. cellent 'pile-on' capability, and the leveliness of dyeings By increasing the number of solubilizing sulfonics, you produced. Dyeings of this type, however, must be after 70 concurrently lower the pH at which the dye will exhaust treated with certain materials such as tannic acid to have onto nylon, and very low pH's will cause fiber degradation 3,343,905 3. 4. hence it is desirable to use solubilized complexes which of the dye composition can be applied sequentally from will dye nylon at pH's of about 4. Premetallized azo 1:1 the same bath or sequentially from different dyebaths-in dye-chromium complexes having the aforesaid character the latter cases, the non-metallized dye component is first istic properties are also a well known class of dyes and applied and thereafter the premetallized dye is applied. heretofore, they have been extensively employed in the The preferred method of application, however, in dyeing of wool. However, because of their poor “pile-on' volves applying the dye compositions made in accordance capabilities, they have not been used extensively for the with the present invention from a substantially neutral dyeing of nylon. The most familiar premetallized 1:1 dye dye bath to dye on the acid dye component and then chromium complexes are the chromium dye complexes lowering the pH so as to dye on the premetallized dye that contain one chromium atom for every o,o'-dihydroxy O component. Generally, the nylon fibers are entered into azo grouping. However, useful premetallized 1:1 dye the dye bath. The temperature of the bath is usually then chromium complexes can be formed from any mordant raised to about 100° C. In order to control the exhaustion dye that has groups that will chelate with trivalent chro rate of the acid dye component the dye bath should be mium in positions vicinal to the azo linkage and wherein at a pH of about 6.5 to 7.5. The time of dyeing will vary one of said vicinal groups should be -OH and the other 5 somewhat with the exhaust rate of the acid nylon dye vicinal group can be a radical such as -OH, -NH2, and component and also with the dyeing characteristics of the -COOH. fiber. Usually, a half hour to one hour treatment at 100' Some premetallized 1:1 dye-chromium complexes such C.