Title:
DYEING SYNTHETICS USING ROLLER COATED MOLTEN DYE COMPOSITIONS
United States Patent 3716330
Abstract:
A process for dyeing fabrics of synthetics fibers which comprised preparing a molten dye composition composed of dyestuff and organic matrix compound which is solid at normal temperature and has compatibility with the dyestuff in molten state, coating the molten composition onto the fabric under the condition not permitting the dyeing of the fabric, then heat-treating the coated fabric to induce the dyeing, and finally removing the remaining coating layer by washing.


Inventors:
Kitamura, Kazuo (Otokuni-gun, Kyoto-fu, JA)
Takabayashi, Fumiki (Ibaraki-shi, Osaka-fu, JA)
Shibata, Fumio (Ibaraki-shi, Osaka-fu, JA)
Application Number:
05/076599
Publication Date:
02/13/1973
Filing Date:
09/29/1970
Assignee:
Teijin Limited (Osaka, JA)
Primary Class:
Other Classes:
8/526, 8/580, 8/602, 8/609, 8/611, 8/929, 8/933
International Classes:
C09B67/42; D06P1/60; D06P1/92; (IPC1-7): C09B67/00; D06P5/04
Field of Search:
8/93,173,176,169
View Patent Images:
Foreign References:
GB1071074A
Primary Examiner:
Lesmes, George F.
Assistant Examiner:
Brammer J. P.
Claims:
We claim

1. A process for dyeing fabrics of synthetic fibers which consists essentially of preparing a dye composition composed of at least one dyestuff selected from the group consisting of non-ionic, anionic and cationic dyes having affinity for the synthetic fibers, and an organic matrix comprising at least one member selected from the group consisting of polyethylene glycols of molecular weight of 1,000- 10,000, polyethylene glycol derivatives selected from the group consisting of ethers and thioethers of polyethylene glycol and adducts of ethylene oxide with aliphatic carboxylic acid amides, adducts of ethylene oxide with aliphatic amines, adducts of ethylene oxide with polypropylene glycol, and esters of a polyhydric alcohol selected from ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, glycerine, pentaerythritol and sorbitan, which are solid at normal temperature and melt at temperatures not higher than 80°C. above the second order transition temperature of the fibers, are soluble in water or a low boiling point organic solvent, and are at least partially compatible with the dyestuff in the molten state; heating said dye composition to melt the same; roller coating the molten dye composition onto the fabric under conditions that allow no substantial penetration of the dyestuff into the synthetic fibers; heat-treating the coated fabric under conditions that allow penetration of the dyestuff component in the coating layer inside the fibers; and thereafter treating the fabric with water or a low boiling point organic solvent to remove the coating layer.

2. The process of claim 1, in which the synthetic fiber is polyester fiber.

3. The process of claim 1, wherein gravure roll is used for the roller coating.

4. The process of claim 1, wherein the dye content of the dyestuff composition is not more than 30 percent based on the total weight of the composition.

5. The process of claim 1, wherein the weight of the coated dyestuff composition is 2 to 50 percent to the total weight of the fabric.

6. The process of claim 1, wherein an antioxidant is added to the dyestuff composition in a quantity of 0.1- 5 percent based on the total weight of the composition.

7. The process of claim 1, wherein the dyestuff composition composed of the dye and organic matrix is pre-formed into a solid material.

Description:
This invention relates to novel dyeing process of fabrics by synthetic fibers.

Conventionally practiced typical dyeing methods of fabrics of synthetic fibers include dip dyeing and pad dyeing such as pad thermosol process and pad steam process. Dip dyeing refers to the practice of immersing the fabric to be dyed in an aqueous dyeing bath and gradually raising the bath temperature. Although the process has an advantage of uniformity in dyed color tone, it has the defect of low productivity because it is practiced batchwise, consequently consuming long time and requiring many hands. Pad dyeing normally refers to the process comprising immersing the fabric in a dyestuff dispersion, removing from the fabric the excessive dye liquid by squeezing it with mangle, etc., thereafter pre-drying the fabric and heating the same to fix the dye. With this process continuous operation is possible, and the productivity can be advantageously improved. However, the process still is subject to the following numbers of drawbacks. That is, when dye concentration in the dye-badding bath is increased, the bath becomes susceptible to change with passage of time, e.g., formation of sedimentation due to aggregation of the dyestuff, and the dispersion in the padding bath becomes instable. Consequently, such objectionable results as ending, uneven coloring, formation of specks, etc. take place. Thus the dyestuff concentration in padding bath is inevitably limited. Furthermore, in the pad thermosol process, products of deep color are hardly obtainable because dissipation of dye into the heated atmosphere due to sublimation during the heating for fixing of the dye is conspicuous, and also the soiling of dye-fixing apparatus is heavy. For these reasons, preparation of uniformly and deeply dyed fabrics is extremely difficult. Again, the aforesaid pre-drying is normally practiced in pad dyeing in general, but the drying efficiency is low, and uniform drying is extremely difficult. Thus, non-uniform dyeing due to migration of dyestuff caused by non-uniform drying is almost inevitable. These defects are particularly conspicuous with thin or thick textiles. Therefore, application of pad dyeing is seriously limited. In addition thereto, the methods's advantage, i.e., high production rate, is fully manifested only for mass production of single brand fabrics. With production of minor quantities of many different brands, the methods's productivity is greatly reduced, since preparatory steps such as cleaning are very time-consuming.

The object of the present invention is to provide a novel method of dyeing fabrics of synthetic fibers, which shows very high productivity and is capable of deep color dyeing with excellent uniformity.

Another object of the invention is to provide a novel dyeing method which achieves substantial simplification of procedures and reduction in labor, and exhibits high applicability to production of minor quantities of many different brands.

The above objects are accomplished by the subject process for dyeing fabrics of synthetic fibers, which comprises preparing a dyestuff composition composed of at least one dye selected from the group consisting of non-ionic, anionic and cationic dyes having affinity to said fabric, and organic matrix composed of at least one of aliphatic polyhydric compounds which are solid at normal temperature and melt at temperatures not higher than 80°C. above the second order transition temperature of the synthetic fibers, are soluble in water or a low boiling point organic solvent, and are at least partially compatible with the dye at molten state, and derivatives of such compounds; heating the composition to form melt thereof; coating the melt onto the fabric under the conditions as will cause no substantial penetration of the dye into the synthetic fibers; heat-treating the coated fabric under the conditions as will allow penetration of the dye component in the coating into the fibers; and thereafter treating the fabric with water or the low boiling point organic solvent to remove the coating.

The subject process will be explained in further details hereinbelow.

The term, "fabric" is used in this specification and claims to mean sheet-formed fibrous materials such as woven goods, knit goods, non-woven fabrics, carpet, and film, composed of filaments or spun yarns. The phrase that "at least partially compatible at molten state" used in the specification and claims means that the organic matrix employed in the subject process either completely dissolves the dyestuff employed, or at least partially dissolves the dyestuff and uniformly and stably disperses the rest, at molten state. The organic matrix preferably dissolves at least 0.1 wt.% of the used dyestuff at molten state.

The most characteristic features of the subject process reside in the preparation of a melt of non-aqueous dyestuff composition composed of dyestuff and organic matrix which is solid at normal temperature but is easy-melting, and is at least partially compatible with the dyestuff at molten state; coating of the melt onto the fabric to be dyed, forming a uniform coating layer of said dyestuff composition, under the conditions as will cause no substantial penetration of the dye component of the composition into the synthetic fibers constituting the fabric, (i.e., at this stage the fabric is substantially undyed), and the following heat-treatment of the coated fabric to cause penetration of the dye component in the coating layer inside the synthetic fibers and achieve the dyeing of the fabric. According to the subject process, the dye component substantially penetrates into the fibers only at the heat-treating stage to achieve dyeing of the fabric. For this reason the heat-treating step may be hereinafter referred to as dye-fixing step.

We discovered that, in the subject process it is an important requirement for obtaining dyed fabric of uniform color and pleasant handling, to perform the coating under the conditions as will allow no substantial penetration of the dye component in the composition into the fibers. In a process wherein substantial penetration of the dye component into the fibers takes place at the coating time, it is necessary to maintain the molten dyestuff composition in the container at high temperatures over a prolonged period, which tends to induce thermal decomposition of organic matrix and the dyestuff, conspicuously deteriorating the product's quality. Also if the coating is effected by padding or roller coating, the fabric is inevitably subjected to considerably high pressures of the roller, etc. Such pressures exerted at high temperatures renders the handling of product markedly coarse and flat. Also when the coating is performed by padding, if dye adsorption takes place during the coating, the dye concentration in the molten dyestuff composition contained in a vessel gradually decreases, causing appreciable change in adsorbed dye concentration between the earlier stage and later stage of the dyeing. Particularly with dyeing using mixture of more than one dyestuffs, the quantitative ratio of dye component in the composition varies with time passage because adsorption rate varies among dyestuffs, occasionally causing such fatal defect in the dyed product such as change in color tone over large areas.

In the subject process, the substantial penetration of dye component into synthetic fibers during the coating of molten dyestuff composition onto the fabric, or prevention of such penetration, is determined mainly by the two factors of the temperature of molten composition at the coating and the time length during which the composition on the fabric is maintained at that temperature. The higher the temperature, and the longer the continuation of high temperature, the greater the tendency of the dye component to penetrate into the synthetic fibers. Therefore, it is generally true that in the coating by immersion of the fabric in a bath of the molten composition, the tendency of dye penetration into the fibers is greater, compared with that in the roller coating, because in the former the composition imparted onto the fabric is maintained at the high temperature for a longer period. Also the higher is the melting point of organic matrix, the greater becomes the tendency of dye penetration into the fibers during the coating.

The fabric coated under the conditions as will allow no substantial penetration of the dye component in the molten dye composition into the fibers according to the subject process is either entirely undyed, or at most very slightly dyed appearing like soiling, if washed with water or a low boiling point organic solvent having solubility of the organic matrix. In this sense it will be safe to state that the fabric is "substantially undyed." Therefore, in practicing the subject process, the coating conditions causing substantially no penetration of dye component of the composition into the fibers can be easily empirically determined. That is, by coating the fabric with the molten dye composition in a preliminary test and subjecting the coated fabric to a washing treatment as above-described, the state of dye adsorption onto the fabric can be examined with naked eye, and suitable conditions can be selected from such test result.

In the subject process, application of the composition by means of roller coating can be said the optimum mode of practice, from the already mentioned reason. When roller coating is adopted, normally the quantity of application can be minor, and furthermore because the contact time of the roller with the fabric is short, the molten dye composition coated onto the fabric is rapidly cooled after the departure of the roller, and solidified within a very short time. Thus formed solid coating layer of the dye composition is neither flowable nor sticky. Therefore during the transfer of the fabric towards the exit of applying apparatus, the phenomenon of the composition's migration from the fabric to the parts of said apparatus such as guide roller or bar contacting with the fabric, to cause soiling the latter (hereinafter this phenomenon will be referred to as contact soil) rarely or never takes place. This is one of the very important advantages of the subject process as later explained.

The fabric thus coated with the dye composition is then heat-treated under the conditions as will allow penetration of the dyestuff component in the coating into the fibers. At this stage for the first time the dyeing of fabric is accomplished. The main factors for determining if the dye penetration takes place during the heating are the heating temperature, time, and atmosphere. That is, the dye penetration into the fibers is promoted, the higher is the heating temperature, and the longer is the heating time. The ease of penetration also differs depending on the heating atmosphere, i.e. whether the heating is effected in air, or in a vessel of open atmosphere under steam supply, or in a air-tightly closed vessel under elevated pressure and steam supply. Generally speaking, the penetration is easier, at a moist state than dry state, and in the presence of moisture, in a closed system at elevated pressure, than in an open system. The preferred heating conditions in accordance with the present invention are normally 150° to 230° for 30 seconds to 40 minutes when dry heat is used; and 140° - 220°C. for 20 seconds to 30 minutes with open system and wet heat. With a closed system and wet heat, the heating at 100° - 130°C. is preferably continued for 10 - 60 minutes. During this heat-treatment, the organic matrix component in the coating layer does not penetrate into the fibers but remains outside of the fibers. Therefore, after fixing the dye component into the fiber by heating, the layer remaining on the fabric, compound mainly of the organic matrix, is removed by washing with water or low boiling point organic solvent which dissolves the organic matrix. The coating step and dye-fixing step of the subject process have been so far described in full details. Although not specified, it should be obvious that the heating must not cause melting of synthetic fibers constituting the fabric, or thermal deterioration to impair handling. From those considerations, the melting temperatures of the organic matrix employed must not exceed at most 80° C. above the second order transition temperature of the synthetic fibers composing the fabric.

In the subject dyeing process, dyestuff composition composed of at least one dye and an organic matrix which is solid at normal temperature and has good compatibility with the dye is used in molten state. Therefore, the dye can be contained at much higher concentrations than those feasible with conventional dye bath, and the molten composition can be uniformly coated onto the fabric even when only minor amount thereof is used, preferably by roller coating system. According to the subject process the sublimation and dissipation of dye into the atmosphere during the heating for dye-fixing as observed in pad thermosol process is substantially eliminated, and therefore deeply dyed fabrics can be obtained with the use of only minor amount of dye. Also because the uniform coating is effected without substantial dyeing of fabric and the dyeing thereof first takes place upon heating of the uniformly coated fabric in accordance with the invention, uniformly dyed fabrics with good handling is readily achieved.

Furthermore, the fabric coated with the dye composition of the invention has the unique property of seldom causing contact soil as already mentioned. Therefore, heretofore invariably required cleaning of the apparatus at each change of dyeing brand is unnecessary with the subject process. Consequently continuous dyeing of many brands with each minor quantity is facilitated for the first time. In conventional dyeing, the apparatus must be cleansed at each alteration of dyeing brand in order to eliminate the detrimental effect of contact soil which inavoidably takes place. This has been the hindrance to continuous production of many brands of each minor quantity of dyed fabrics as desired for those many years. Again, no mutual contact soil takes place between the fabrics coated with the dye composition of the invention. Therefore, it is possible to store the coated fabric as it is, i.e., without the heating treatment for dye-fixing, as continuously withdrawn and wound up into rolls, for any optional period. (This practice is referred to as "batch up" among the dyeing industry). Conventionally, drying of the fabric in advance of winding (pre-drying) has been essential for the batch up, but according to the subject process the fabric can be wound immediately after coating with the dye composition, omitting such drying step, because the composition is non-aqueous and readily solidifiable.

Thus, because the dye composition which solidifies after coating is used in the subject process, the pre-drying normally required in pad dyeing is unnecessary. Consequently, non-uniform dyeing due to migration of dye inevitably accompanying the pre-drying step never takes place, and the limitation on the types of fabric to be dyed is completely eliminated.

Furthermore, if the dye composition employed in this invention is pre-formed into a solid material, it is far easier for handling compared with conventional powdered or liquid dyestuffs, and automatic measuring, supplying, etc. are much facilitated to achieve simplification of procedures and reduction in manual labor.

The fabrics useful in the subject process are those composed of one or more of synthetic fibers such as of polyester, polyamide, polyacrylonitrile, polyvinyl chloride, and dyeable-polyolefine, etc. The advantages of the subject process over the conventional methods are particularly conspicuous when the process is applied to the fabrics of polyester fibers.

Non-ionic dyes intended in the invention include disperse dyes, vat dyes, developed dyes for synthetic fibers, oil-soluble dyes, and non-ionic fluorescent dyes. Also anionic dyes and cationic dyes are those which form, respectively, free dye anions and dye cations in water. Anionic dyes include, for example, acid dyes, acidic mordant dyes, metal-containing acid dyes, etc., and as cationic dyes, for example, basic dyes may be named.

The organic matrix employed in the subject process is at least an aliphatic polyhydric compound or derivative thereof, which is solid at normal temperature and melts at temperatures not higher than at most 80°C. above the second order transition temperature of the synthetic fibers employed. The matrix also is soluble in water or low boiling point organic solvents such as aliphatic lower halogenated hydrocarbons, e.g., carbon tetrachloride, perchloroethylene, and trichloroethylene; lower aliphatic saturated alcohols of no more than 3 carbons, e.g., methanol, ethanol, and propanol; and acetone; and is at least partially compatible with the employed dye in molten state. Specific examples of such include the following: polyethylene glycol of 1,000- 10,000 in molecular weight; mono- or di-ethers derived from polyethylene glycol and alcohols such as methanol, ethanol, propanol, butanol, octanol, lauryl alcohol, cetyl alcohol, stearyl alcohol, oleyl alcohol, benzyl alcohol, etc., or phenols such as t-butyl phenol, octyl phenol, nonyl phenol, lauryl phenol, octyl-β-naphthol, etc; thioethers derived from polyethylene glycol and mercaptans such as lauryl mercaptan; esters derived from polyethylene glycol and aliphatic carboxylic acids such as lauric acid, stearic acid, palmitic acid, etc.; adducts of ethylene oxide with sorbitan esters such as sorbitan monostearate, sorbitan distearate, etc.; adducts of ethylene oxide with aliphatic acid amides such as lauric acid amide, stearic acid amide, etc.; adducts of ethylene oxide with aliphatic amines such as octylamine, laurylamine, stearylamine, eleylamine, etc.; block copolymer of polyoxyethylene and polyoxypropylene (commercially available by the tradename of Pluronic); ethylenediamine adduct of block copolymer of polyoxyethylene and polyoxypropylene (tradename: Tetronic); graft-copolymers of polyethylene glycol, or block copolymer of polyoxyethylene and polyoxypropylene, with vinyl monomers such as methyl acrylate, methyl methacrylate, and vinyl acetate; aliphatic polyhydric alcohols such as sorbitol, arabitol, 2-methyl-2-propyl-1,3-propanediol, etc.; esters of aliphatic polyhydric alcohols such as ethylene glycol monostearate, ethylene glycol distearate, diethylene glycon monopalmitate, triglycerol monostearate, hexaglycerol monostearate, sorbitan monostearate, sorbitan distearate, sorbitan tristearate, glycerine monostearate, glycerine distearate, pentaerythritol monolaurate, pentaerythritol monostearate, etc.

Among the foregoing substances useful as the organic matrix, polyethylene glycol is the most preferred.

Considering the fact that one of the most significant features of the subject process resides in that the dye composition coated on the fabric is readily solidified to form a coating layer free of contact soil, it can be understood that the melting temperature of organic matrix and the ambient temperature should not be too close, because otherwise the solidifying rate of the coating after the application will be reduced. Again the melting temperature should not be too high, because otherwise the melting will be difficult and during the coating operation the tendency of the dye to penetrate into the fabers will be promoted.

Preferred range for the melting temperature of organic matrix is 50° - 100°C. The higher the compatibility of the organic matrix with employed dye, the higher may be the dye concentration in the composition, and uniform coating onto the fabric can be more conveniently performed. Furthermore, the preparation of homogeneous dye composition is much facilitated. Because of those advantages, it is recommended to use the organic matrix having high compatibility with dye if all possible. When highly compatible dye and organic matrix are used in accordance with the subject process, the composition can contain the dye at a concentration of as high as 30 percent to the total weight of the composition, with high stability. Concentrations higher than that should be avoided, because such will impair the dispersion stability and render the uniform application of the composition difficult.

The dye composition of the invention can be formed by homogeneously mixing the dye with organic matrix. In that case, it is also permissible to add other components which assist uniform deep color dyeing, if desired, besides the above two essential components. As one of such additives, antioxidant may be named. That is, depending on specific combination of organic matrix and dye, decoloration of dye may occur during the heating for dye-fixing, and the decoloration is presumably caused by oxidation with air. Such decoloration can be effectively prevented by adding antioxidant. As useful antioxidants, those which are compatible with the organic matrix are preferred. Suitable antioxidants are, for example, 2,2'-methylene-bis(4-methyl-6-tertiary-butyl-phenol), 4,4'-thio-bis(6-tertiary-butyl-3-methylphenol), 1,1'-bis(4-hydroxyphenyl)cyclohexane, mercaptobenzimidazole, zinc salt of mercaptobenzimidazole, tri(nonylphenyl)phosphite, and phenothiazine, etc. Such antioxidant is added preferably within the range of 0.1 - 5 percent based on the total weight of the composition. As another type of additives, those which assist the dispersing and dissolving of dye in the molten organic matrix, such as ethylene carbonate, glycerine, diethylene glycol, thiodiethylene glycol, ethanolamine, diethanolamine, dimethylformamide, dimethylsulfoamide, dimethylacetamide; sorbitan monooleate, polyoxyethylene sorbitan monolaurate, polyoxyethylene lauryl ether, etc., may be named.

Furthermore, assistants of dye-fixing which promote fixing of dye, such as paraphenyl phenol, orthophenyl phenol, methyl naphthalene, etc. which are the dye-fixing promotor normally utilized for aqueous dyeing of polyester, may be named. Those can be added in minor quantities when necessary.

When anionic dyes are used, occasionally the uniformity in application and dyeing is improved when water or an organic acid such as formic or acetic acid is added in a minor quantity (at most 5 wt.% or below) to the dye composition. Obviously, the quantities of those additives should be within the range as will not impair the property of the organic matrix that it is solid at room temperature.

When anionic dyes are used, the fabric which finished the dye-fixing step may be passed through an acidic aqueous solution. Whereupon the dyed color on the fabric may be deepened. This step itself is known as "acid shock" among the dyeing industry.

Commercial dyes occasionally contain additives which are insoluble in the molten organic matrix, which may interfere with the uniform dispersibility of the composition during the preparation of molten composition of the dye and organic matrix, to result in occurrence of dye specks, etc. Therefore, for effective practice of the present invention, it may be desirable that such additives in the commercial dyes which are insoluble in said organic medium are removed in advance.

As the means for applying the molten dye composition to fabric, immersion of the fabric in the bath of said composition is not impossible. However, roller coating is far more desirable for the full exhibition of unique features of subject process. One of the reasons therefor is that roller coating is convenient for preventing penetration of the dye into the fibers at the time of coating, as already mentioned, and another is that with roller coating, the dye composition containing the dye at a high concentration can be daubed onto the fabric in a minor quantity and with uniformity, consequently improving effective utilization of the dye. Among the roller coating of various systems, that using gravure roll capble of uniform daubing under elevated temperatures is the most suitable for the subject process. In the roller coating, the suitable quantity of dye composition ranges 2 - 50 percent to the weight of fabric. For the daubing operation of the dye composition onto fabric, in certain cases advance moistening treatment of the fabric, e.g., spraying of a liquid liquid compatible with the organic matrix onto the fabric, assists uniform daubing. As such a liquid, for example, water, perchloroethylene, trichloroethylene, or methanol, acetone, and mixtures thereof, may be named.

Thus coated fabric is then subjected to a heat-treatment for fixing the dye. If necessary, the coated fabric may be forcedly cooled to accelerate solidification of the coating layer, or pre-heated to facilitate the uniform application of dye onto the fabric, in advance of the last heat-treatment.

The heated fabric on which the dye is thus fixed is finally washed, to be removed of the coating. The most preferred cleaning agent is water. The washing is often effectively performed by adding an alkaline substance such as sodium carbonate, caustic soda, sodium bicarbonate; reducing agent such as sodium hydrosulfite; and dispersing agent, etc. to water. Furthermore, the aqueous washing may be replaced by washing treatment with low boiling point organic solvent such as perchloroethylene, trichloroethylene, methanol, acetone, etc.

Hereinafter the invention will be explained in fuller details, with reference to working examples. In the examples, the numeral value in the parentheses of the indication such as, for example, polyoxyethylene (20) stearate means the average addition mol number of ethylene oxide.

EXAMPLE 1

To 445 parts of polyethylene glycol of 4,000 in average molecular weight and melting at 53° - 56°C. which was melted by heating at 70°C., 40 parts of a refined disperse dye of the structural formula,

and 15 parts of mercaptobenzimidazole as an antioxidant were added, and the whole system was mixed for 3 hours in a ball mill which was heated at 70°C. to cause dissolving and dispersing. Thus a melt of homogeneous dye composition was obtained.

The apparatus used for the coating comprised two coating units disposed in vertical relation and other auxiliary devices such as guide bars to continuously lead the fabric to the coating units, and an expander to outstretch the fabric in the direction of its width to assist smooth supply of the fabric to the rollers. Also one coating unit consisted of a gravure roll, and a back roller incidental thereto, a knife coater, and a coating bath. The two coating units were so disposed that each one could coat the respective single surface of the fabric fed thereto. The gravure rolls and coating baths were maintained at 70°C. by circulation of warm water therethrough. The above melt composition was poured into the coating baths, and continuously coated onto the two sides of woven fabric of polyethylene terephthalate filaments which was fed at a rate of 3 m/min, immediately followed by batch up. The quantity of the coating was 20 % to the weight of the fabric. Thus coated fabric was subjected to dye-fixing treatment of various conditions as shown in Table 1, to cause penetration of the dye in the coating layer into the fibers, and washed with an aqueous solution containing each 2 g/l of sodium hydrosulfite, caustic soda, and polyoxyethylene (20) stearylamine, at 80°C. for 20 minutes. Drying the fabric, uniform pink color dyeing was achieved. The deepness of the dyed color was expressed by lightnees (L-value) measured by color-difference meter, with the results as shown in Table 1 below. ##SPC1##

During the foregoing dyeing procedures, when the coated fabric before the dye-fixing treatment was washed with acetone at room temperature for a short time, the coating layer was completely washed off, and the fabric had an L-value of 73.0, showing the whiteness close to that of the untreated starting fabric. This indicates that substantially no dye adsorption took place at the time of coating. Entirely no contact soil to the back roller, guide roller, etc. during the continuous coating onto both sides of the fabric was observed, and neither any non-uniform dyeing due to transfer of the coating layer upon contact between the fabrics during batch up occurred.

EXAMPLE 2

Under the dyeing conditions of Example 1, the quantity of dye (the same dye as employed in Example 1) applied to the fabric (owf %) was varied in each run as indicated in Table 2 below, and the mercaptobenzimidazole was replaced by 1 percent to the total weight of the composition of phenothiazine. Also the treated fabric was changed to that woven of highly twisted polyethylene terephthalate filaments, and the conditions for fixing the dye were changed as shown in Table 2. All other conditions being identical with those of Example 1, the fabrics dyed in various shades of pink were obtained. The L-values of the fabrics corresponding to the deepness of dyed color were measured with the results shown in Table 2.

For comparing the subject process with conventional pad dyeing, the same fabric as employed above was dyed under the following conditions: the dye used in Example 1 was dispersed in water, and to which sodium alginate was added at a concentration of 1 g/l to make an aqueous dye solution. In that procedure, the dye concentration in the solution was so adjusted that the dye pick-up (percent based on the weight of fabric) of the fabric after being immersed in the solution and squeezed with mangle at a fixed squeez ratio should give the various values as specified in Table 2. (The dye pick-up (percent) based on the weight of fabric will be referred to as "owf".) The fabrics were immersed in the so prepared aqueous solutions, squeezed of excessive liquid, air-dried, and fixed of the dye under the identical conditions with those employed in Example 2. The L-values of the dyed fabric obtained of the control runs are also shown in Table 2.

Table 2

Temp. × Time Atmosphere of owf (%) Dye-fixing (°C.) (min) 1 2 4 Subject 44.8 39.9 37.7 process Dry heat Control 45.7 45.0 44.9 150 × 130 Subject 42.1 38.6 34.7 process One system, wet heat Control 44.9 41.8 42.5 Subject 43.0 37.9 33.9 process Dry heat Control 42.8 41.4 40.6 160 × 30 Subject 41.6 37.5 32.3 process Open system, wet heat Control 42.1 39.8 39.1 Subject 41.0 37.4 31.7 process Dry heat Control 42.1 38.7 36.6 200 × 1 Subject 42.5 37.0 30.7 process Open system, wet heat Control 42.6 38.0 32.1

Upon comparing the L-values obtained of the subject process and controls, it can be understood that under same owf (percent) the fabrics tend to be dyed more deeply in the subject process than in the control runs, and the tendency is emphasized under high owf (percent). This persuasively demonstrates that the present process is very advantageous for dyeing fabrics in deep colors.

EXAMPLE 3

In this Example, as to the coating step of the subject process, the influence of temperature at the coating time and its duration on the penetration of dye component in the molten dye composition into the filaments was examined, using various combinations of fabrics and dyes. The operating conditions were as follows:

a. 284 Parts of polyethylene glycol of 3,500 in average molecular weight was melted at 60°C., and to which 8 parts of a refined disperse dye of the structural formula,

and 8 parts of mercaptobenzimidazole were added, and milled for 2 hours in a ball-mill of 60°C. Then at the temperature and for the time shown in Table 3a, fabrics woven of polyethylene terephthalate filaments were immersed in the composition, withdrawn, and immediately thrown into cold water to be cooled. Then the fabrics were washed first with 50°C. warm water, and then with an aqueous solution containing each 2 g/l of caustic soda, sodium hydrosulfite, and polyoxyethylene (20) stearylamine, at 80°C. for 20 minutes. After the subsequent drying, the coated fabrics were measured of their lightness (L-values) as a norm for evaluating the deepness of dyed color, with the results as shown in Table 3a.

b. The operations of above a) were repeated except the following changes: polyoxyethylene (5) stearic acid amide was used as the organic matrix; 8 parts of unrefined, commercial acid dye of the structural formula,

was used as the dye; woven fabric of nylon-6 filaments was used as the material to be dyed; and the washing of coated fabric was performed in an aqueous solution containing 2 g/l each of sodium carbonate and polyoxyethylene (15) lauryl ether, at 60°C. and for 20 minutes. The L-values of so treated fabrics are shown in Table 3b.

c. The operations of above (a) were again repeated except the following changes: as the dye, 8 parts of unrefined, commercial cation dye of the structural formula, ##SPC2##

was used; fabrics woven of acrylic staple fibers were used; and the washing of coated fabric was performed similarly to (b) above. The L-values of the treated fabrics are shown in Table 3c.

Table 3a

Temp. °C. Time 60 80 100 120 140 160 180 200 (sec) 1 73.3 73.8 74.5 74.2 70.9 62.5 48.4 39.7 5 73.3 74.9 74.0 74.2 67.7 53.7 41.3 31.4 10 73.9 74.8 75.0 73.5 65.8 53.9 39.1 28.7 30 74.2 75.0 74.4 73.0 61.6 46.1 33.7 26.4 60 73.5 74.2 73.8 7.27 55.7 41.7 28.4 23.8 (Note) The L-value of untreated fabric was 74.3

Table 3b

Temp. (°C.) 60 80 100 120 140 160 180 200 Time (sec) 1 68.8 68.5 67.2 67.6 61.8 55.8 46.8 39.4 5 67.0 68.8 65.4 65.7 57.4 52.3 42.3 37.3 10 67.4 67.4 67.8 64.1 55.7 45.5 37.5 33.7 30 67.2 68.1 68.6 62.0 52.2 36.4 30.4 31.6 60 68.8 66.5 66.7 60.7 45.2 32.7 25.5 29.3 (Note) The L-value of untreated fabric was 68.5

Table 3c

Temp. (°C.) 60 80 100 120 140 160 180 200 Time (sec) 1 60.2 62.7 62.6 61.7 63.6 67.0 57.8 63.7 5 62.2 62.2 62.8 61.3 58.7 60.6 57.2 59.5 10 63.4 60.4 61.7 62.1 59.5 63.1 56.6 52.8 30 61.7 61.7 63.2 62.4 64.2 58.1 55.2 51.8 60 60.6 62.5 61.7 60.1 64.8 55.7 45.1 45.9 (Note) The L-value of untreated fabric was 62.7

The color tone of the treated polyethylene terephthalate fabrics of (a) was violet, but under the conditions giving L-values not less than 55, for example, 60 seconds or less at the treating temperature of 140°C., and not longer than 1 second at 160°C., no dyeing or very slight coloring appearing like soiling took place. Thus it could be said that no substantial dyeing took place. The nylon-6 fabrics obtained in (b) appeared blue, but under the conditions giving L-values of not less than 55, e.g., not longer than 10 seconds at the treating temperature of 140°C., and not longer than 1 second at 160°C., no substantial dyeing took place in the sense similar to the above explanation.

The acrylic fabric treated in (C) was imparted with clear orange color, but under the conditions giving L-value of not less than 55, e.g., not longer than 60 seconds at the treating temperature of 160°C., not longer than 30 seconds at 180°C., and not longer than 5 seconds at 200°C., no substantial dyeing took place.

Then the influence of coating conditions on the penetration of dye into the filaments was examined also in the case gravure roll coating as employed in Example 1 was practiced, using only one coating unit. The coating bath and gravure roll were maintained at 70°C., 90°C., 110°C., 140°C., and 160°C., in each run, by circulation of hot oil. The same dye composition as employed in (a) was applied also to the same fabric as of (a) by gravure roll, at a feed rate of 0.6 m/min. The contact time of the fabric with the heated gravure roll was approximately 0.5 second. The coated fabric was washed similarly to (a), and dried. All the products showed L-values of not less than 55, and were substantially undyed.

EXAMPLE 4

The coating of Example 1 was repeated except that a refined disperse dye of the structural formula,

was used as the dye, and organic matrix was varied in each run as indicated in Table 4, to examine susceptibility to contact soil of coated layer at the coating time. As a means to numerically express the degree of soiling tendency, the following measurement was performed. The coating layer as applied on the fabric was subjected to a friction test with the untreated, starting white fabric of identical brand, for the predetermined number of times, and the degree of soil on the untreated fabric caused by the coating layer was judged with naked eye with 5-level grey scale. (In the grey scale, 1 corresponds to black and 5, white, and the intermediate 2 through 4 correspond to each different shade of grey.) The soiling tendency to the apparatus and between fabrics was confirmed to have good correlation with the result of above grey scale evaluation.

In this Example, not only the organic matrices which are solid at normal temperature, but also those which are normally liquid were used as controls. The results are shown in Table 4, in which the variation in measured values caused by changing the number times of friction are also shown. The ambient temperature of the measurement was 26°C.

Table 4

Number Times of Friction Condition Organic Matrix of 5 10 20 30 40 50 25°C. Polyethylene glycol (average molecular Solid 4-5 3-4 3 3 3 3 weight: 4,000) Polyoxyethyl- ethylene (30) do 4 4 3 3 3 3 stearate Polyoxyethylene do 4 3 3 3 3 3 (30) stearyl ether Polyoxyethylene (100) lauryl do 4 3 3 3 3 3 ether Polyethylene glycol Liquid 2 2 1 1 1 1 (average molecular weight: 200) Polyoxyethylene do 2-3 2 1 1 1 1 (5) octylphenol Polyoxyethylene do 2-3 2 1 1 1 1 (3) lauryl ether

As clearly demonstrated in Table 4, the organic matrixes which are solid at normal temperature as specified in the subject process show very little contact soil compared with those which are liquid at normal temperature.

EXAMPLE 5

Example 1 was repeated except the following changes: as the dye, a refined disperse dye of the structural formula,

was used; the polyethylene glycol of 4,000 in average molecular weight was replaced by the organic matrixes specified in Table 5; addition of mercaptobenzimidazole was omitted; the temperatures at the melting and mixing of the dye in the organic matrix and at the coating time were varied as shown in Table 5; and the heating for dye-fixing was effected by dry heat of 200°C. for 1 minute. The L-values corresponding to the lightness of dyed color of the fabric were as shown in Table 5 below.

Table 5

Melting Dye-mixing L-value Organic Matrix Temp. of and Coating of Matrix Temp. Dyed (°C.) (°C.) Fabric Polyethylene glycol (average molecular 47-53 70 44.0 weight: 2,000) Polyethylene glycol (average molecular 58-62 80 44.5 weight: 6,000) Polyethylene glycol (average molecular 65-68 90 44.2 weight: 10,000) Polyoxyethylene (58) 47-54 70 43.9 octyl ether Polyoxyethylene (30) 46-49 65 42.0 stearyl ether Polyoxyethylene (50) 49-54 70 41.0 oleyl ether Polyoxyethylene (100) 57-59 80 44.1 nonyl phenol Polyoxyethylene (50) 42-53 70 39.4 lauryl phenol Polyoxyethylene (50) 48-52 70 42.3 octyl-β-naphthol Polyoxyethylene (50) 45-49 65 43.0 lauryl thioether Polyethylene glycol (average molecular 48-50 65 44.8 weight: 2,200) methyl nonylphenyl diether Polyethylene glycol (average molecular 44-50 65 43.7 weight: 2,200) benzyl nonylphenyl diether Polyoxyethylene (30) 40-45 65 43.9 stearate Polyoxyethylene (10) 46-52 70 41.2 distearate Ethylene glycol mono- 57-59 80 41.5 stearate Diethylene glycol 44-47 65 39.6 monopalmitate Polyoxyethylene (6) 47-55 70 41.1 sorbitan monostearate Polyoxyethylene (54) 41-48 65 45.2 lauric acid amide Polyoxyethylene (50) 47-56 80 45.6 octylamine Polyoxyethylene (105) 50-54 70 44.9 stearylamine Polyoxyethylene (20) 48-52 70 44.4 oleylamine Polyoxyethylene (159) polyoxypropylene (51) ethylenediamine 49-51 70 41.9 (tradename: Tetronic) Polyoxyethylene (100) polyoxypropylene (21) block copolymer 48-51 70 40.5 (tradename: Pulronic) Polyethylene glycol (average molecular 57-58 80 43.0 weight: 3,700)- methyl acrylate graft-copolymer Polyethylene glycol (average molecular weight: 3,700)- 51-52 70 42.1 vinyl acetate graft-copolymer Sorbitol 95-98 115 40.7 2-Methyl-2-propyl- 1,3-propanediol 52-58 80 32.2 Sorbitan monostearate 46-50 70 38.3 Sorbitan tristearate 57-61 80 38.2 Glycerine monostearate 76-77 95 40.4 Triglycerol mono- stearate 46-53 70 42.1 Pentaerythritol mono- 54-62 80 41.3 stearate

In those runs, when the coated fabrics before the dye-fixing treatment were washed with hot acetone for a short time, the coating layers completely came off, and the remaining fabrics had the whiteness close to that of the starting uncoated fabrics. This indicates that the dye penetration under the coating conditions given in Table 4 can be entirely disregarded.

EXAMPLE 6

A knit good was dyed under the conditions given in Example 1, except the following changes: that as the starting material, thick knit good made of textured yarns of polyethylene terephthalate filaments was used; that gravure roll of greater coating capacity was employed to apply 20 percent to the weight of the knit good of the dye composition; that the heating for dye-fixing was effected by dry heat at 160°C. for 20 minutes; and that the washing after the dye-fixing was effected by immersion in perchloroethylene. Thus a knit good uniformly dyed pink throughout the inside of fabric and which had a good handling was obtained. The L-value of the product was 44.2. When the knit good after the coating but before the dye-fixing treatment was washed with hot acetone, the coating layer was substantially completely removed, and the remaining good had an L-value of 73.1. Incidentally, the untreated starting material had an L-value of 74.8.

Whereas, when the gravure rolls and coating baths were heated to 185° - 190°C. by circulation of hot oil, feed rate of the fabric at the coating time was drastically reduced, and the contact space of the gravure rolls with the knit good at the coating time was sufficiently enlarged to render their contact time approximately 5 seconds; the dye component in the molten dyestuff composition considerably penetrated into the fiber during the coating, and the knit good was dyed. That is, when the good was washed with perchloroethylene similarly to the above-described run immediately upon completion of the coating, the knit good was dyed pink, and had an L-value of 48.2. However, the knit good dyed in the control run showed so-called surface dye adsorption, i.e. the surface thereof was dyed deep pink, and inside of the fibers was dyed in medium to light shade of the pink. Therefore the product had an appearance much inferior to that of the product obtained through the process in accordance with the subject invention. Furthermore, because in the control the coating baths were maintained at high temperatures, the dye in the coating baths was thermally decomposed as the time passed, and consequently occurrence of spots such as specks was observed on the dyed goods. Again the handling of the product of control was flat and coarse, and it was confirmed that the pleasant handling of the starting knit good of textured yarn was remarkably impaired.

EXAMPLE 7

To 480 parts of sorbitan monostearate which was melted at 70°C., 3 parts of a refined disperse dye of the following structural formula,

and 30 parts of another disperse dye of the structural formula,

(commercial product, unrefined) were added, and milled for 4 hours in a ball mill heated at 70°C. to form a homogeneous melt of dye composition. It was put in a container and maintained at 70°C. to provide a padding bath. Thick cloth woven of textured yarns of polyethylene terephthalate filaments was continuously immersed in the melt, and excessive melt pick-up was squeezed off with a mangle heated at 70°C., for preventing the melt from solidifying on the fabric. The coated quantity in this operation was 58 wt.%. During the operation the dye component in the coating layer showed no penetration into the fibers. The coated fabric was heat-treated with dry heat of 180°C. for 2 minutes, and washed under the same conditions as described in Example 1. Thus a uniformly dyed, orange fabric was obtained. The color tone of the fabric was consistently the same throughout the dyeing operation, and no change with time passage was observed. The product also had a good handling.

As a control, the padding bath was heated to 200°C., and the coating was effected under the condition that the fabric was immersed therein for 30 seconds. In this run the dye component of the molten composition penetrated into the fibers during the coating, and the fabric leaving the padding bath was dyed orange even after the washing. When this control process was run continuously, the color tone on the product showed changes with time passage, i.e., at earlier stage of the dyeing the color tone was more reddish and the reddish shade was reduced as time passed. This phenomenon was caused by the difference in dyeing rate of the two dyes employed. Also because the padding bath was maintained at thigh temperatures for a prolonged period in the control run, decomposition of the dyes took place, causing spot formation such as specks. Furthermore the control product had coarse handling, indicating deterioration of the handling of textured yarn fabric.

EXAMPLE 8

Using the fabrics composed of various filaments as shown in Table 6, dyeing was experimented under the conditions given in Example 1, with the following changes: that the dyes indicated in Table 6 were used for dyeing each of the fabrics; that the use of mercaptobenzimidazole was omitted; that the dye-fixing was effected under the heating conditions specified in Table 6, and that the dyed fabrics were washed with 60°C. warm water containing 1 g/l of non-ionic surfactant (polyoxyethylene (15) lauryl ether). The products were uniformly dyed in the shades varying from light to deep. The L-values of the products are also shown in Table 6. ##SPC3##

In this Example, penetration of the dye into fibers during the coating either did not occur, or if at all observable, appeared as light as soiling. Thus, substantial dyeing took place in no run.

EXAMPLE 9

Example 1 was repeated except the following changes: that a commercial acid dye (unrefined) of the structural formula below, ##SPC4##

was used; that thin cloth woven of nylon-6 filaments was used; that one of the two gravure rolls was rendered idle to effect coating on one surface only; that immediately before the cloth was continuously led to the gravure roll, water was uniformly sprayed onto the fabric (the quantity of spraying water was 30 percent to the fabric weight); and that the washing after dye-fixing was effected similarly to Example 8. In this run, the spraying of water, coating, heating for dye-fixing (dry heat; 180°C. × 2 minutes) and washing were continuously performed. Thus obtained product was dyed clear blue, excellent particularly in uniformity of color. The advantage of applying water to the fabric before the coating was exhibited by uniform distribution of the dye conposition over the entire fabric surface. Consequently, although single surface coating was effected in this run, the product showed no difference in color tone between the two surfaces.

EXAMPLE 10

To 320 parts of polyoxyethylene (5) stearic acid amide melted at 70°C., 80 parts of the acid dye employed in Example 9 was added, and dissolved and dispersed in the former by 4 hours' milling in a ball mill heated at 70°C. The composition was coated onto a fabric woven of nylon-6 filaments similarly to Example 1. The coated fabric was then treated with steam at 190°C. for 1 minute in open system, and thereafter subjected to an acid treatment at 98°C. for 1 minute, in an aqueous solution containing 10 g/l of 85 percent formic acid. The fabric was further washed in an aqueous bath containing 2 g/l of sodium carbonate and 2 g/l of non-ionic surfactant, at 60°C. for 20 minutes. Thus the fabric was dyed clearly and deeply. The lightness of the dyed color expressed by L-value was 28.20. When the acid treatment was omitted in the above run for comparison, the L-value of the dyed fabric was 33.82. This result indicates that the above acid treatment is effective for obtaining deeply dyed fabric.

EXAMPLE 11

To 450 parts of polyethylene glycol of 3,000 in average molecular weight, 50 parts of a commercial acid dye (unrefined) of the structural formula,

and 10 parts of water were added, and milled similarly to Example 1. The dye composition retained the property of being solid under normal temperature, under the addition of water, and the homogeneity of the melt was improved. The composition was coated at 70°C. onto one surface only of tufted carpet made of textured yarns of nylon-6 filaments, using one gravure coating unit only of the assembly used in Example 1. The gravure roll employed was that having a greater coating capacity. The condition of carpet after the coating was such that the solidified dye composition adhered on the top of pile of the carpet, showing no penetration down to the root of pile. The coated carpet was allowed to stand under dry heat of 100°C. for 10 minutes by way of pre-heating. Whereupon the coating layer was formed uniformly throughout the height of pile. At this stage, however, still the dye in the coating layer showed no substantial penetration inside the fibers. The carpet was then steamed under dry heat of 180°C. for a minute to fix the dye, and washed with heated perchloroethylenes. Thus the carpet uniformly dyed deep blue to the root of pile was obtained.

In the control run wherein the pre-heating before the dye-fixing treatment was omitted, undyed portion was observed at the root of pile. This proves that the pre-heating preceding the dye-fixing (heating under the conditions causing no fixing of dye) assists the uniform penetration of the dye in the coating layer into the intrastructure of the fabric, achieving excellently uniform dyeing.

EXAMPLE 12

Example 1 was repeated except the following alterations: that a refined vat dye of the structural formula,

was used as the dyestuff; that the mercaptobenzimidazole was replaced by other antioxidant as specified in Table 7; and that the fixing of dye was effected by the dry heat treatment as specified in the same table. The decoloration due to decomposition of the dye was judged with naked eye. For comparison, results of the control run wherein the use of antioxidant was omitted are also given.

Table 7

Antioxidant Conditions of Dye-fixing Treatment and Quantity Added 170°C. 190°C. 210°C. (parts) ×30 min. ×5 min. ×0.5 min. Mercaptobenz- imidazole 5 5 5 5 Sodium sulfides 2.5 Phenothiazine 5 5 5 5 2,2'-methylenebis (4-methyl-6-t- butylphenol) 15 4-5 5 5 Control 1 2 2-3

In the above table, the evaluations ranging from 1 to 5 denote the degree of decoloring by relative grading i.e., absolutely no decoloration (the sample fabric fixed of the dye in an air-tightly closed vessel at 130°C. for 30 minutes with saturated steam, the dyeing conditions inducing no decoloring) was graded 5, and completely decolored product was graded 1; the intermediate state being dicided into three equal spans as judged with naked eye. From the above result, the effectiveness of anti-oxidant's addition can be clearly understood.

EXAMPLE 13

To 445 parts of the molten organic matrix used in Example 1, 25 parts of a refined fluorescent dye of the structural formula,

as the dye, and 20 parts of polyoxyethylene (4) sorbitan monolaurate as an additive, were added, and the fixing of dye was effected by dry heat of 200°C. for 1 minute, otherwise the dyeing conditions being identical with those described in Example 1. Thus fluorescent, whitened fabric of excellently uniform whiteness was obtained.

EXAMPLE 14

Referring to Example 1, the dye composition as formed and melted was poured into a cylindrical iron container, and allowed to cool off to room temperature. Thus a solid, cylindrical dye composition of 5 cm in diameter and 15 cm in length was obtained. Also for making a similar solid, the refined disperse dye used in Example 5 was finely rushed, thoroughly mixed with polyethylene glycol flakes of 4,000 in average molecular weight, in a tumbler at room temperature, and put in the above iron container. As the pressure was reduced from the bottom, the mixture was compression-molded under a pressure of 140 kg/cm2 exerted by a piston from the top. Thus another solid composition of the similar form was prepared. Separately the melt of dye composition obtained in Example 1 was formed into flakes with flaking machine, and further formed into grains of 3 mm in diameter with a granulating machine.

As described above, the dye composition employed in the subject process can be made into shaped products of various forms by various methods, because it is solid at normal temperature.