| PATENT ASSIGNEE'S COUNTRY | Germany |
| UPDATE | 04.00 |
| PATENT NUMBER | This data is not available for free |
| PATENT GRANT DATE | 04.04.00 |
| PATENT TITLE |
Process for continuous dyeing of cellulosic circular knits with water-soluble dyes |
| PATENT ABSTRACT |
Process for continuous dyeing of cellulosic circular knits composed of natural or modified hydroxy-containing or natural, modified or synthetic carboxamido-containing fiber materials with water-soluble dyes comprises initially impregnating the material with an aqueous dye solution, optionally comprising auxiliaries, in the course of the dyeing step, reducing the liquor content to 400% by weight, based on weight of fiber, by squeezing means customary for tubular material, and subsequently subjecting the liquor-comprising material to a leveling and fixing step for the dye applied to the material by transporting the rope of material continuously through the machine unit by means of the flowing dyeing liquor at a liquor ratio of up to 10:1. |
| PATENT INVENTORS | This data is not available for free |
| PATENT ASSIGNEE | This data is not available for free |
| PATENT FILE DATE | 05.11.98 |
| PATENT FOREIGN APPLICATION PRIORITY DATA | This data is not available for free |
| PATENT REFERENCES CITED | This data is not available for free |
| PATENT CLAIMS |
What is claimed is: 1. A continuous process for dyeing circular knit materials composed of natural or modified hydroxy-containing or natural, modified or synthetic carboxamide-containing fiber materials with water-soluble dyes, which comprises initially impregnating the material with an aqueous dye solution, reducing the liquor content in the course of impregnating the material with the aqueous dye solution to 400% by weight, based on weight of fiber, by squeezing means, and subsequently subjecting the liquor-containing material to a leveling and fixing step for the dye applied to the material by transporting the material continuously through the the aqueous dye solution by means of a flowing dyeing liquor at a liquor ratio of up to 10:1. 2. A process as claimed in claim 1, wherein the liquor content of the material after its impregnation with the dye solution is reduced to 150 to 350% based on weight of fiber. 3. A process as claimed in claim 1, wherein the leveling and fixing step is effected at a liquor ratio of 6:1 to 10:1. 4. A process as claimed in claim 1, performed in a jet dyeing machine. 5. A process as claimed in claim 1, wherein the material moves cocurrently with the treatment liquors. 6. A process as claimed in claim 1, wherein the treatment liquor moves countercurrently to the material. 7. A process as claimed in claim 1, wherein a reactive dye is used in the dyeing step. 8. A process as claimed in claim 1, wherein the material to be dyed consists of cellulosic fiber material. 9. A process as claimed in claim 1, wherein the treatment liquors are applied to the material via jet nozzles and the treatment liquors transport the material through the dyeing apparatus via said jet nozzles. 10. A process as claimed in claim 1, wherein the material in the treatment step is plaited down in the treatment liquors in individual chambers of a dyeing apparatus and passes through the chambers in the plaited down form. |
| PATENT DESCRIPTION |
Continuous processes for dyeing flat fabrics with reactive, direct, vat or disperse dyes by padding methods are established in the art and always provide good results if carried out correctly. Serviceable machinery and standardized dyes ensure a uniform fabric appearance. The situation is different with the dyeing of circular knits. The currently most widely used method for dyeing circular knits is the batchwise exhaust method. Both continuous and semicontinuous methods for dyeing such materials have distinct disadvantages with regard to the appearance of the dyed material. For instance, the semicontinuous dyeing of circular knits with fiber-reactive dyes by the cold pad-batch method gives rise, for example, to crease marks due to the plaiting of the impregnated material in boxes, which greatly reduces the quality of the eventual made-up article. In addition, the fixing times are of the order of hours, making efficient dyehouse management very difficult. Circular knits can also be dyed in a continuous manner by a pad-steam process, but it too has disadvantages as a consequence of creasing, insufficient color yield, nonuniform appearance and two-sidedness. Also, marks due to liquor running back are observed. Furthermore, U.S. Pat. Nos. 4,351,076 and 4,483,032 disclose wet-processing, especially dyeing, ropes of textile material in jet dyeing apparatus. In this operation, the textile material, which is in rope form on a batchwise or piecewise basis and which is guided past the nozzles, is either set into circulation with the aid of the treatment liquor circulating in the same direction by the nozzle system or is moved on by means of a gas stream or vapor/air mixture being directed at the fiber material from the nozzles under overpressure. The main feature of this processing technique is that the textile material in endless form is conveyed through the machine by the kinetic energy of the tangential jet, it being possible for gas and liquid flow to be alternated or combined during the different treatment stages, which permits a seamless transition from one dyeing step to another without a standstill of the material and under isothermal conditions. In the discontinuous dyeing method described in U.S. Pat. No. 4,483,032, which is based on the aerodynamic propulsion of the textile rope, the dyeing jet is entered with the fiber material lotwise; in the dyeing jet, the dyeing liquor is applied to the material by injecting it into the circulating gas stream in atomized form, each time giving fresh impetus to the circulation of the textile material and of the treatment liquor not absorbed by the material. The application of the total liquor quantity takes place over a plurality of circulations of the material, and the continuous recirculation of the excess liquor ensures uniform distribution of the liquor not only on but also in the rope and hence excellent levelness of the treatment outcome. When the dyeing operation has ended, the piece-dyed material is removed again from the jet. According to this reference, the dyeing method it describes can also be carried out continuously, but it does not disclose any technical details for a continuous form. All the directions in this reference concerning practical handling consistently relate to the discontinuous form of the process. U.S. Pat. No. 4,592,107, however, discloses a process and apparatus for the continuous treatment of ropes of textile material which are in elongate form, i.e., not in endless form, by likewise propelling the textile material by application of the jet principle hydraulically and aerodynamically in alternation. In the course of its passage, the textile rope passes through a series of successive machine units having optionally different objectives, i.e., using selectively different treatment agents or treatment conditions preferably for the wet treatment operation. There is provision here for distinct and diverse treatment stages, clearly separated from one another by rope inlet and rope outlet. Although this operating principle of the multiple impingement of liquid treatment agents on the rope is said to be adaptable to any desired process or processing sequence, it is in fact exclusively employed for washing and cleaning purposes with the goal of improving the so-called dilution factor between two successive wet treatment stages, e.g., the aftertreatment of already dyed fiber material by means of liquor advantageously flowing in the opposite direction to the textile material. The intermediary storing of the moist textile material from a preceding wet treatment mainly has a dewatering purpose so that the effectiveness of the respective treatment operations may be increased. So, this reference neither prevents nor suggests a genuine dyeing process plus dye fixation on a continuous basis. However, the favorable experience of U.S. Pat. No. 4,483,032 with regard to the propulsion of rope-shaped textiles in jet apparatus by means of a gas stream and also the possible application of treatment agents combined with simultaneous provision of the necessary physical conditions by the gas responsible for propelling the material made it appear possible that this aerodynamic system could also be utilized for fully continuous operation. Accordingly, U.S. Pat. Nos. 4,885,814 and 4,947,660 describe a process for the continuous dyeing of textile material in rope form by means of jet dyeing machines by effecting the propulsion for the transportation of the material via the kinetic energy of a circulating gas stream by means of a nozzle system. The underlying object was to design the application conditions for the colorant in such a way as to obtain a uniform dyeing in a fully continuous manner using ideally a single, ideally minimal liquor application and ideally under isothermal conditions. In the process, the liquor quantity is determined in such a way that all the liquor applied remains within the rope and no excess, migrating liquor appears even in the course of the subsequent fixation. However, this process is technically not implementable for reactive dyes, since the marks produced during the single, minimal dye application never level out in the further course of the isothermal process described, contrary to the statements in the reference; after all, since the dye solution already contains all the chemicals necessary for fixing reactive dyes, the fixing process starts immediately after the isothermal impregnation. During the further transportation by the gas or gas/vapor mixtures, no further migrating liquor is available for any leveling, and any unlevelness once it has been produced is no longer evened out. Furthermore, during the aerodynamic transportation of the rope by a thermally treated gas, applied dye solution is blown about, which causes local concentration differences and consequent unlevelness on the dyed material. A further disadvantage of this process is that the material is merely plaited down following a nozzle passage and does not float in excess treatment liquor; the material's own weight leads to markings which likewise become irreversibly fixed under the process conditions. It is an object of the present invention to provide a continuous process for dyeing circular knits composed of natural or modified hydroxy-containing or natural or modified or synthetic carboxamido-containing fiber materials with water-soluble dyes, preferably reactive dyes, without the aforementioned disadvantages, chiefly the formation of crease and runoff marks, and with good fixation of the dye coupled with good penetration. This object is achieved by the present invention. The invention accordingly provides a continuous process for dyeing circular knit materials composed of natural or modified hydroxy-containing or natural, modified or synthetic carboxamido-containing fiber materials with water-soluble dyes, which comprises initially impregnating the material with an aqueous dye solution, optionally comprising auxiliaries, in the course of the dyeing step, reducing the liquor content to 400% by weight, based on weight of fiber, preferably to within the range from 150 to 350% by weight, by squeezing means customary for tubular material, preferably by ring- to oval-shaped squeezing means, and subsequently subjecting the liquor-comprising material to a leveling and fixing step for the dye applied to the material by transporting the rope of material continuously through the machine unit by means of the flowing dyeing liquor at a liquor ratio of up to 10:1, such as 6:1 to 10:1, especially 7:1 to 10:1. The dyeing process is preferably carried out in a jet machine, and the treatment liquors (starting dye solution, a solution to effect dye fixation on the fiber material and a mixture thereof) are preferably applied to the material via venturi or jet nozzles (hereinbelow referred to for simplicity as "jet nozzles"), the treatment liquors transporting the material through the dyeing apparatus via the jet nozzles. In the dyeing process of the present invention, the rope of textile material is initially impregnated with the aqueous dye solution in a very short liquor, approximating a padding step; the subsequent leveling and fixing step corresponds to the methods of exhaust dyeing in a medium liquor ratio in the manner defining the invention, so that a dye solution, once it has been applied, is able to migrate and fix level on the textile tube material with the dye detaching from the fiber only to an extremely small extent, if at all. The process of the present invention additionally has the advantage of making it possible to reduce significantly the amounts of electrolyte salt which are customary for the application of water-soluble, especially anionic, dyes and of the alkali required to fix reactive dyes on the fiber. Hydroxy-containing fiber materials are for example cellulosic fiber materials, such as the natural fiber materials, like cotton, jute and linen, and the modified fiber materials produced from cellulosic natural materials, like regenerated cellulose, for example filament viscose rayon, and cellulose fibers modified with amino-containing compounds, as are known for example from U.S. Pat. Nos. 5,507,840, containing compounds, as are known for example from U.S. Pat. Nos. 5,507,840, 5,565,007 and 5,529,585, from European patent application publication No. 0 665 311 and from German Offenlegungsschrift 19 519 023. Carboxamido-containing fiber materials are natural fiber materials, such as wool and other animal hairs, and also silk, and synthetic polyamide fiber materials, such as fiber materials composed of nylon-6, nylon-11 and nylon-6,6. Dyes which can be used in the dyeing process of the present invention include all water-soluble dyes, especially those which are anionic in nature. Dyes having anionic, i.e., acidic, water-solubilizing groups are for example acid and direct dyes, e.g., C.l. Acid Black 27 (C.l. No. 26 310), C.l. Acid Black 35 (C.l. No. 26 320), C.l. Acid Blue 113 (C.l. No. 26 360), C.l. Direct Orange 49 (C.l. No. 29 050), C.l. Direct Orange 69 (C.l. No. 29 055), C.l. Direct Yellow 34 (C.l. No. 29 060), C.l. Direct Red 79 (C.l. No. 29 065), C.l. Direct Yellow 67 (C.l. No. 29 080), C.l. Direct Brown 126 (C.l. No. 29 085), C.l. Direct Red 84 (C.l. No. 35 760), C.l. Direct Red 80 (C.l. No. 35 780), C.l. Direct Red 194 (C.l. No. 35 785), C.l. Direct Red 81 (C.l. No. 28 160), C.l. Direct Red 32 (C.l. No. 35 790), C.l. Direct Blue 162 (C.l. No. 35 770), C.l. Direct Blue 159 (C.l. No. 35 775), C.l. Direct Black 162:1 and C.l. Direct Violet 9 (C.l. No. 27 885). Further dyes whose use is suitable for the process of the present invention are sulfur dyes or vat dyes in their water-soluble form. However, the process of the present invention is particularly useful for dyeing with fiber-reactive dyes. As fiber-reactive dyes may be mentioned in particular those where the fiber-reactive radical is a radical of the vinyl sulfone series, for example vinylsulfonyl or an ethylsulfonyl group which is substituted by an alkali-eliminable substituent in the .beta.-position, such as .beta.-sulfatoethylsulfonyl, .beta.-acetoxyethylsulfonyl, .beta.-chloroethylsulfonyl or .beta.-thiosulfatoethylsulfonyl, also fiber-reactive radicals of the chlorotriazinyl, fluorotriazinyl, fluoropyrimidinyl and chlorofluoropyrimidinyl series, and also dyes possessing combinations of such reactive groups. The abovementioned dyes useful for the dyeing process of the present invention are extensively described in the literature and well known to the person of ordinary skill in the art; fiber-reactive dyes are described for example in the patent specifications mentioned at the beginning and also in European patent application publication No. 0 513 656. The dyeing process of the present invention can be used for treating all customary circular knit articles, such as single jersey, loop plush, interlock, fine rib, piquet and lining or trainer fabrics. The dye solution with which the tubular material is impregnated at a very short liquor ratio may, as mentioned, comprise auxiliaries, for example buffer substances, wetting agents, crease-mark inhibitors, leveling aids, migrating aids and, if necessary, dye solubility enhancers, further the synthesis-based electrolyte salts customary in the case of water-soluble dyes, such as sodium sulfate, sodium chloride, lithium chloride and potassium chloride. The starting dye solution comprises the dye in the amount required for the particular depth of shade, for example in an amount of up to 150 g per liter. The process of the present invention can be carried out not only according to the cocurrent principle, whereby the textile material and the dyeing and fixation liquors or treatment liquors move in the same direction, but also according to the countercurrent principle, whereby the dyeing and fixing liquors or treatment liquors move through the chambers in the opposite direction to the textile material. In both cases, the fixing step is carried out under the conditions which are customary for the particular choice of dye and for the particular choice of fiber material, such as dyeing temperature and addition of suitable fixing aids and of any other auxiliaries required, as extensively described in the literature, and well-known to the person of ordinary skill in the art, for the particular dyes and fiber materials. For instance, fiber-reactive dyes in particular are fixed on the fiber material, especially on cellulosic fiber material, using an alkaline aqueous fixing liquor comprising per liter up to 50 g of electrolyte salt such as sodium chloride, potassium chloride and/or sodium sulfate, and up to 30 g of an alkaline agent, such as sodium carbonate or sodium hydroxide. Reactive dyes are preferably fixed using an aqueous alkaline fixing solution comprising per liter 10 to 30 g of sodium sulfate and 10 to 30 g of sodium carbonate. BRIEF DESCRIPTION OF THE DRAWINGS Novel features and advantages of the present invention in addition to those mentioned above will become apparent to persons of ordinary skill in the art from a reading of the following detailed description in conjunction with the accompanying drawings wherein similar reference characters refer to similar parts and in which: FIG. 1a is a diagrammatic view illustrating the dyeing process and apparatus of the present invention carried out according to the cocurrent principle; FIG. 1b is a diagrammatic view illustrating the process and apparatus of the present invention where the dyeing apparatus of FIG. 1a is connected to upstream apparatus operated by jet nozzles; FIG. 2 is a diagrammatic view illustrating the dyeing process and apparatus of the present invention carried out according to the countercurrent principle; and FIG. 3 is an enlarged sectional view of one of the jet nozzles. In what follows, the principle of the two procedures is illustrated by FIGS. 1a and 2; their reference characters have the following meanings: ______________________________________ W.sup.0 = tubular material to be dyed W.sup.1 = dyed tubular material A = aqueous dye solution B = aqueous fixing solution C = the dye solution (dyeing liquor) comprising fixing agent B D = liquor outlet E = cloth redirector Q = squeeze means P = pump for treatment liquor V = jet nozzle K.sup.0 and K.sup.1 = impregnating chambers with dye solution A K.sup.2 to K.sup.6 = dwell chambers ______________________________________ The principle of the continuous procedure in cocurrent form is hereinbelow illustrated with reference to FIG. 1a: The material W.sup.0 passes as an endless circular knit tube through the dyeing apparatus of FIG. 1a, which, via chamber K.sup.6, is connected to a washing apparatus for the dyed material W.sup.1. Apparatus part K.sup.1 to K.sup.6 illustrates the principle of a jet dyeing machine. The tubular material passes through jet nozzles (V.sup.1 to V.sup.6) and is transported through the apparatus by means of treatment liquors (A, B and C) which are driven through the jet nozzles by pumps P; it moves at high speed (within the range from 30 to 60 m/min) and, between the individual nozzle passages, is plaited down in layers in the chambers (K.sup.0 and K.sup.1 to K.sup.6) in which it continues to move slowly within about 5 to 10 minutes. The material W.sup.0 entering K.sup.0 is treated with the dye solution in K.sup.0 and K.sup.1, passage through V.sup.1 ensuring complete impregnation. K.sup.0 and K.sup.1 communicate with each other, whether by overflow or a line, so that A can flow back from K.sup.1 to K.sup.0 . The material impregnated with A in K.sup.0 may, if appropriate, pass into K.sup.1 by passing through a customary squeeze means (Q.sup.0), for tubular material, for example a ring-shaped rubber lip, to reduce the liquor content. As the impregnated material transfers from K.sup.1 to K.sup.2 the liquor content of the material reduces to about 150 to 400% by weight, on weight of fiber, due to a customary squeeze means (Q.sup.1) for tubular material. Jet nozzle V.sup.2 then presses the fixing liquor B into the material containing the dye solution A (if the leuco form of vat dyes is used, B can be a solution containing an oxidizing agent; if fiber-reactive dyes are used, it can be an aqueous solution containing an alkaline agent). The liquor present in K.sup.2 and formed of A and B is pumped by P.sup.3 from K.sup.2 via V.sup.3 to K.sup.3 ; the same operation repeats from K.sup.3 to K.sup.4, from K.sup.4 to K.sup.5 and from K.sup.5 to K.sup.6. In this way, the tubular material is intensively repeatedly impregnated with the dyeing liquor C, which is maintained at the necessary treatment temperature in all regions, and is able to dwell in the individual chambers K.sup.2 to K.sup.6 for a sufficient time to fix the dye on the fiber (or to form and fix the dye in the case of vat dyes). Spent liquor C can be removed from the dyeing apparatus through discharge D.sup.6. The dyed material W.sup.1, on which the dye has become fixed, is--while still saturated with liquor C--freed from liquor C as much as possible via squeeze means Q.sup.6 and then passed into a customary rope washer downstream of this jet machine, it being possible for the material to be transported, similarly to the jet dyeing machine, via jet nozzles through which the aftertreatment liquors (such as water at various temperatures, aqueous alkali-neutralizing solutions, aqueous detergent solutions). FIG. 1b illustrates the principle of an apparatus where the dyeing apparatus of FIG. 1a is connected to an upstream apparatus which is operated by means of jet nozzles in a similar manner to the jet dyeing machine. This upstream apparatus with the chambers G.sup.0, G.sup.1, G.sup.2 and G.sup.3 is used for bleaching raw cotton circular knit material which, after the bleaching step, can be fed directly into the dyeing apparatus (as per FIG. 1a). Similarly to chambers K.sup.0 and K.sup.1, the material is impregnated with the bleaching solution in chambers G.sup.0 and G.sup.1, which communicate with each other, and the unbleached raw material (W.sup.U) is bleached or aftertreated via the jet nozzles V.sup.G1, V.sup.G2, V.sup.G3 with the various treatment liquors (such as bleaching solution G.sup.L, a peroxide-reducing solution G.sup.P and an acetic acid solution G.sup.E which neutralizes the material). Between each treatment step in the individual chambers G.sup.1 or G.sup.2 or G.sup.3, the material saturated with the corresponding treatment liquor and passing from one chamber to the other has the treatment liquor removed from it as intensively as possible by squeeze means Q. The bleached material emerging from G.sup.3 is then introduced into the impregnating chamber K.sup.0, which holds dye solution A, and the subsequent dyeing step can then proceed similarly to the description for FIG. 1a. The principle of the dyeing process employing the principle of countercurrent treatment, whereby the treatment liquor (dyeing liquor C) flows in the opposite direction to the material to be dyed, is to be illustrated with reference to FIG. 2: As in the process of FIG. 1a, the material is initially impregnated with dye solution A in impregnating chambers K.sup.0 and K.sup.1 and after reduction of the liquor content of the material to about 150 to 400% by weight, on weight of fiber, by a squeeze means (Q.sup.1) customary for tubular material introduced into chamber K.sup.2 via jet nozzle V.sup.2. In accordance with the countercurrent principle, the treatment liquor C (such as a dye solution which contains electrolyte salt and has an alkaline action in the case of reactive dyes) is transferred by a pump (P.sup.5) from the last chamber (K.sup.6) of the dyeing machine into the preceding chamber (K.sup.5) and in the course of the transfer applied via a jet nozzle (V.sup.5) to the tubular material passing through this jet nozzle. The agent required for fixing the dyes, such as an alkaline agent in the case of fiber-reactive dyes, is continuously forced in the form of treatment liquor B into chamber K.sup.6 and onto the tubular material via jet nozzle V.sup.6, the liquor B mixing in K.sup.6 with the dyeing liquor entrained by the tubular material from K.sup.2 to K.sup.6 to form the liquor C.sup.1 (which, as the material exits from K.sup.6, is squeezed off by means of Q.sup.6 as much as possible and returns into K.sup.6). Liquor C.sup.1, which is rich in fixing agent B, fixes remaining, unfixed dye portions. Similarly to the transfer of liquor C.sup.1 from K.sup.6 to K.sup.5, the liquor C transfers in further steps into whichever is the preceding chamber K (as from K.sup.5 to K.sup.4 etc.) in order to be pressed via the corresponding jet nozzles onto the tubular material and to be able to dwell in the respective chamber to fix the dye. In this way, the tubular material coming from whichever is the preceding chamber is already impregnated with the dye solution A containing the fixing agent B (equal to treatment liquor C), and the particular treatment liquor C in the preceding dyeing chamber (dwell chamber), for example C.sup.3, has--as a consequence to the contrary movement of the liquor C to the textile material--a somewhat higher dye content and a lower B content than in the subsequent dyeing chamber, for example C.sup.4. This operation is repeated a number of times. K.sup.2 is the final destination of a treatment liquor (C.sup.4) having only a minimum amount of fixing agent B left, which can be discharged via D from K.sup.2. The gradual decrease in the level of fixing agent B (such as the alkaline agent when fiber-reactive dyes are used) in the liquors C on going from C.sup.1 to C.sup.4 and, conversely, the gradual increase in the level of B on the tubular material during transportation through chambers K.sup.2 to K.sup.6 bring about even, uniform fixing of the dye applied to the tubular material during the dwell time in the chambers of 30 to 60 minutes in total. Each of the treatment liquors, whether in the cocurrent procedure of FIGS. 1 or according to the countercurrent procedure of FIG. 2, is maintained in the particular chambers K at the temperature necessary for the particular treatment. The Examples hereinbelow illustrate the invention. Parts and percentages are by weight, unless otherwise stated. Parts by weight relate to parts by volume as the kilogram relates to the liter. |
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