PROCESS FOR DEGREASING AND DESIZING FABRICS HAVING SYNTHETIC FIBERS
United States Patent 3630661
Synthetic textiles are both degreased and desized by passing the textiles through a bath of an anhydrous solvent containing a dissolved alkaline agent. The textile is then preferably rinsed in a compatible solvent.
Inventors:
Ramier, Georges (Villefranche sur Saone, FR)
Blanc, Remy (Lyon ler, FR)
Blanc, Remy (Lyon ler, FR)
Application Number:
04/886418
Publication Date:
12/28/1971
Filing Date:
12/18/1969
View Patent Images:
Export Citation:
Assignee:
Societe Civile dite Soltex (Paris, FR)
Primary Class:
Other Classes:
8/142, 28/167, 8/138, 8/139, 8/137
International Classes:
D06L1/06; D06M11/38; D06M13/35; D06M23/10; D06L1/00; D06M11/00; D06M13/00; D06M23/00; D06L1/02
Field of Search:
8/142,137,138,139,139.1
Primary Examiner:
Weinblatt, Mayer
Claims:
What is claimed is
1. Process for degreasing and desizing textile fibers and threads which are protected by a coating of mineral oil and polyacrylic acid or its derivatives, which comprises
1. Process for degreasing and desizing textile fibers and threads which are protected by a coating of mineral oil and polyacrylic acid or its derivatives, which comprises
Description:
The present invention relates to a new method for simultaneously degreasing and desizing fabrics, and, more particularly, to removing grease and sizing products from fabrics containing synthetic resins.
Textile fibers or threads, and especially artificial (viscose, cellulose diacetate and triacetate) or synthetic (polyamides, polyesters, polyacrylic, polyvinylic, polypropylenic materials, etc.) fibers are protected generally by a coating, usually constituted with a fatty product applied as an aqueous emulsion or as a solution; such a protection is herein called "greasing." When the fibers are intended for weaving and use as warp they must receive a further protection constituting sizing. Size has a different nature according to thread nature; for synthetic fibers it is usually polyacrylic acid or similar polymers.
Greasing and sizing must in some manner be suppressed, usually by some washing operation, before the dyeing operation. Insofar as thread dyeing is concerned, regardless of the dyeing technique, only degreasing is necessary. The same is true for the dyeing of knit fabrics. For woven fabric dyeing, on the other hand, the weft must be degreased and the warp both degreased and desized.
The conventional processes of grease removal use aqueous baths containing emulsifying agents and detergents, used along or in mixture.
Desizing operations are adapted to the nature of the sizing. Where the size is polyacrylic acid, the desizing agents are bases or alkali metal salts which give rise to a salification of the polyacrylic acid to the form of water-soluble salts. In this case, those salts may be present together with degreasing ingredients. To be efficient in a short time, the operation must be carried out at a temperature between 60° C. and 90° C. Moreover when knit or woven fabrics containing synthetic fibers or threads are concerned, this operation must necessarily come before any thermal fixing treatment, for fear that the fixing operation will make it impossible to degrease and desize. Accordingly, it is necessary to dry the fabric after desizing. Even if thermofixing is achieved after dyeing or printing, drying remains necessary in most cases, with an expensive outlay of heat required to remove a residual water ratio of 50 percent minimum, in textile material, after squeezing. This expense is to be added to the one of motive power, workmanship, and amortization of expensive and bulky dryers and stenters.
Furthermore, degreasing and especially desizing, which are generally followed with rinsing in running water, consume and pollute a very great volume of water.
In accordance with the present invention, a convenient and easy process has now been provided which allows the simultaneous suppression of greasing products based upon fatty materials and sizing products based upon polyacrylic acid.
The process according to the invention consists of achieving, according to known techniques and devices, a dissolution of the precited coating substances in an anhydrous medium, by means of an organic solvent or solvent mixture containing, dissolved therein, an organic or an inorganic alkaline agent.
While any organic solvent may be used, nonpolar or polar, it is preferred to use as nonpolar solvents halogenated hydrocarbons, e.g. carbon tetrachloride, trichloroethylene, perchlorethylene (tetrachlorethylene), trifluorotrichloroethane, ethylene dibromide; and as polar solvents aliphatic alcohols such as methanol, isopropanol or isobutanol.
The mixture may comprise a mixture of several polar solvents or several nonpolar solvents or both polar and nonpolar solvents. It may be advantageously the azeotrope formed by an halogenated nonpolar solvent and a polar solvent having one or several alcohol functions, the interest of such a mixture being to obtain on one hand a better dissolving power with regard to some fatty substances which may be contained in the greasing composition, and on the other hand an inflammability lower than the one of the alcoholic polar solvent. To this advantage is added the additional advantage of making easier the recovery of the solvent mixture, by distillation. An example of such an azeotrope is that formed by isopropanol and tetrachlorethylene.
As an alkaline agent there may be used an organic base as for example: pyridine, piperidine and similar substances, or an inorganic base such as potassium hydroxide or a mixture of inorganic and/or organic bases. Any alkaline agent may be used which is soluble in the selected organic solvent.
A rinsing is necessary to remove the dissolved elements; it may be achieved by a solvent and advantageously by one of the constituents of the degreasing-desizing bath. Thus, tetrachloroethylene may be used as a rinse when the degreasing-desizing bath is constituted with the azeotrope isopropanol/tetrachlorethylene.
The advantages brought by the process according to the invention are numerous:
1. It may be operated at room temperature and during a very short time, because of the high dissolving power.
2. Further drying is reduced or avoided provided that rinsing solvents or solvent mixtures are chosen for which the boiling point is as low as possible and lower in any case than water. If the solvent vapor pressure at room temperature is high enough, the provision of air aspiration may be sufficient to make drying unnecessary and allow the direct and immediate contact of the textile with the dyeing bath, if such dyeing bath contains only organic solvents and if the treatment of thermal fixing is achieved on dyed fabric. Of course this implies that there is compatibility between the solvents of the degreasing-desizing bath and the solvents of the dyeing bath.
If thermal fixing comes before dyeing, such fixing may also be effected without previous drying provided that the apparatus in which it is achieved is fitted with means to recover the organic solvents.
3. Water consumption and corresponding pollution are nonexistent.
4. Solvents may be regenerated, by means of distillation or any other method, and be recycled in a following operation. The solvent consumption is reduced by recovery operations and may easily be limited to about 5 percent.
5. To the savings of heat energy resulting from cold treatment and from drying suppression is added an important decreasing of labor cost owed to the quickness of treatment.
The system comprising solvent agent (pure or mixture) and alkaline agent may be applied to the textile material to be treated using the common means, that is:
either moving of liquid through the fixed textile material as is generally the case for cake threads, reels or hanks
or by moving of the textile substance in fixed liquid as it is generally the case for woven or knit fabrics treated on winch vessels, jiggers, course vats, pads, etc.
The process according to the invention may be applied with devices of common type, provided that metals and joints have a nature able to resist the solvents and that the conventional convenient measures are taken with regard to solvent vapors, so as to catch the vapor for a distillation recovery, and to maintain staff safety and buildings salubrity.
From the point of view of process exploitation it is very important to be able to easily control the results even when carried out by a nonspecialized staff, instead of under laboratory control, which is always possible but which takes a long time and, accordingly, does not allow in case of need of an immediate correction. Therefore a means of testing and control has now been developed using the property of polyacrylic acid to become nonsoluble under the effect of dry heat to immediately give a green coloration with the reagent known under the name of "Identex II" (furnished by the Society "Francaise des Matieres Colorantes").
For the polyacrylic acid, the critical temperature from which this green coloration is obtained on a nondesized fabric is 170° C.; this polymer is made nonsoluble by the heat necessarily applied for fiber thermal fixing. Consequently it is desirable to test, if, after desizing, there remains any polyacrylic acid which may be made nonsoluble by fixing treatment. From this point of view it has been discovered that by contacting the fabric to be tested with series of studs heated to temperatures having between them a gradation from 171° C. up to the upper temperature at which such treatment is achieved, it is possible to obtain a valuable quotation to measure desizing degree.
If, as an example, the fabric to be tested is a polyamide 6--6, which will subsequently be thermofixed at 210° C. and if the gradual series of studs has 4 of them between 171° C. and 213° C., for example 176°-183°-193°-204°, the number 1 can be assigned to the stud at 171°, 2 to 176°, 3 to 183°, 4 to 193°, 5 to 204° and 6 to 213°; and the desizing degree, quoted as numbers 1 to 6, will be obtained when Identex II is applied to a textile material, the green color appearing on the surface having been in contact with studs, 1,2,3,4,5 or 6 during equal times and pressures.
An easy way to achieve this test is to use an apparatus with studs of the "Thermotest" type built by the Firm ADAM, designed for the purpose of controlling sublimation resistance of dyes on synthetic fibers and having in a range of standardized temperatures the following values: 149°-154°-158°-161°-165°-171°-17 6°-183°-204°-213°-225°-229° C. Besides this apparatus has 5 scales of 13 temperatures, according to stud heating degree, that is:
for degree A of heating : 119° to 177°
" " B " : 129° to 194°
" " C " : 139° to 212°
" " D " : 149° to 229°
" " E " : 159° to 246°
So, it is possible to choose one of the scales (for example the scale D in the example quoted hereinbefore) and keep it with regard to synthetic fibers to be the most usually tested. Thus, to use this apparatus, it is sufficient to take from the desized fabric a strip of 6 cm. × 40 cm., to put it during 45 seconds in contact with the range of heated studs, from stud 171° up to 229°, to immerse the strip in an aqueous solution containing 1 g./1. of reagent "Identex" at 15° C.; to soap quickly in the hot, to rinse and to note from which stud the green color appears.
It is obvious that any device allowing a contact of a well-determined time under a determined pressure with hot surfaces of precise temperatures would fit as well as ADAM thermotest, which is indicated here only as an illustrative tester and because it is of great interest in units treating synthetic fabrics.
The following applications of the degreasing/desizing process according to the invention and of its control are indicated in the illustrative examples hereinafter.
EXAMPLE 1
The experimentation is made on a polyamide 6--6 taffeta of 95 g./m. 2 and the warp of which has a polyacrylic acid sizing at the rate of 1 to 2 percent of warp weight and the weft of which has a greasing with emulsified mineral oil at the rate of 1 percent of oil with regard to fabric weight. The dry unbleached fabric is passed at the speed of 100 m./min. in a pad with two rolls giving a squeezing ratio of 65 percent in a bath at 18° C. composed per 100 liters of:
70 l. of isopropanol
30 l. of tetrachlorethylene
300 gm. of solid potassium hydroxide
The fabric, wound at pad outlet, is stored in roll for 24 hr. at room temperature. Then it is rinsed at the speed of 15 m./min. in a roller-vat having a run of 5 m. in tetrachloroethylene maintained at the temperature of 80° C. The vat has at its outlet a squeeze device to remove solvent up to 80 percent. Then the fabric passes in a short stenter comprising a vaporization chamber maintained at the temperature necessary for solvent removing, provided with a device for solvent vapors catching and a thermofixing chamber maintained at 210°; the total duration of passage through the stenter does not exceed 2 min. The fabric wound at the stenter outlet is adapted for dyeing directly.
Desizing degree is controlled on a strip taken from the storage roll after the 24 hr. storage. This strip is rinsed hastily in a beaker containing tetrachlorethylene brought to 80° C., then dried, contacted during 1 minute with heated studs of an ADAM thermotest and at last immersed during 1 minute in the reagent "Identex II" at 15° C., then washed and rinsed.
Desizing degree quotation is 6 : consequently the degree of desizing is excellent.
EXAMPLE 2
A polyamide-6 linen of 80 g./m. 2 is wound in a closed jigger in which is introduced a 10 percent solution of piperidine in trichlorethylene.
Only one passing of the linen is achieved at a maximal speed in the bath at room temperature. The roll is extracted from jigger and stored during 24 hr. at room temperature while maintaining it in slow rotation.
Then the roll is circulated in a second closed jigger containing a trichlorinated ethylene bath maintained at 80°. Only one passage is made at maximum speed. The jigger has at its outlet a squeezing device followed by a short vaporization chamber with solvent vapor recovery, and winding at the outlet of the fabric preparatory for printing in turn followed with a thermal fixing.
The control achieved according to the same modalities as in example 1 is limited to quotation 3 for desizing, because the maximal temperature for polyamide 6 does not exceed 180° C. This is good desizing under the required conditions.
The above exemplifications of the invention are offered illustratively and modifications may be made without departing from the invention.
Textile fibers or threads, and especially artificial (viscose, cellulose diacetate and triacetate) or synthetic (polyamides, polyesters, polyacrylic, polyvinylic, polypropylenic materials, etc.) fibers are protected generally by a coating, usually constituted with a fatty product applied as an aqueous emulsion or as a solution; such a protection is herein called "greasing." When the fibers are intended for weaving and use as warp they must receive a further protection constituting sizing. Size has a different nature according to thread nature; for synthetic fibers it is usually polyacrylic acid or similar polymers.
Greasing and sizing must in some manner be suppressed, usually by some washing operation, before the dyeing operation. Insofar as thread dyeing is concerned, regardless of the dyeing technique, only degreasing is necessary. The same is true for the dyeing of knit fabrics. For woven fabric dyeing, on the other hand, the weft must be degreased and the warp both degreased and desized.
The conventional processes of grease removal use aqueous baths containing emulsifying agents and detergents, used along or in mixture.
Desizing operations are adapted to the nature of the sizing. Where the size is polyacrylic acid, the desizing agents are bases or alkali metal salts which give rise to a salification of the polyacrylic acid to the form of water-soluble salts. In this case, those salts may be present together with degreasing ingredients. To be efficient in a short time, the operation must be carried out at a temperature between 60° C. and 90° C. Moreover when knit or woven fabrics containing synthetic fibers or threads are concerned, this operation must necessarily come before any thermal fixing treatment, for fear that the fixing operation will make it impossible to degrease and desize. Accordingly, it is necessary to dry the fabric after desizing. Even if thermofixing is achieved after dyeing or printing, drying remains necessary in most cases, with an expensive outlay of heat required to remove a residual water ratio of 50 percent minimum, in textile material, after squeezing. This expense is to be added to the one of motive power, workmanship, and amortization of expensive and bulky dryers and stenters.
Furthermore, degreasing and especially desizing, which are generally followed with rinsing in running water, consume and pollute a very great volume of water.
In accordance with the present invention, a convenient and easy process has now been provided which allows the simultaneous suppression of greasing products based upon fatty materials and sizing products based upon polyacrylic acid.
The process according to the invention consists of achieving, according to known techniques and devices, a dissolution of the precited coating substances in an anhydrous medium, by means of an organic solvent or solvent mixture containing, dissolved therein, an organic or an inorganic alkaline agent.
While any organic solvent may be used, nonpolar or polar, it is preferred to use as nonpolar solvents halogenated hydrocarbons, e.g. carbon tetrachloride, trichloroethylene, perchlorethylene (tetrachlorethylene), trifluorotrichloroethane, ethylene dibromide; and as polar solvents aliphatic alcohols such as methanol, isopropanol or isobutanol.
The mixture may comprise a mixture of several polar solvents or several nonpolar solvents or both polar and nonpolar solvents. It may be advantageously the azeotrope formed by an halogenated nonpolar solvent and a polar solvent having one or several alcohol functions, the interest of such a mixture being to obtain on one hand a better dissolving power with regard to some fatty substances which may be contained in the greasing composition, and on the other hand an inflammability lower than the one of the alcoholic polar solvent. To this advantage is added the additional advantage of making easier the recovery of the solvent mixture, by distillation. An example of such an azeotrope is that formed by isopropanol and tetrachlorethylene.
As an alkaline agent there may be used an organic base as for example: pyridine, piperidine and similar substances, or an inorganic base such as potassium hydroxide or a mixture of inorganic and/or organic bases. Any alkaline agent may be used which is soluble in the selected organic solvent.
A rinsing is necessary to remove the dissolved elements; it may be achieved by a solvent and advantageously by one of the constituents of the degreasing-desizing bath. Thus, tetrachloroethylene may be used as a rinse when the degreasing-desizing bath is constituted with the azeotrope isopropanol/tetrachlorethylene.
The advantages brought by the process according to the invention are numerous:
1. It may be operated at room temperature and during a very short time, because of the high dissolving power.
2. Further drying is reduced or avoided provided that rinsing solvents or solvent mixtures are chosen for which the boiling point is as low as possible and lower in any case than water. If the solvent vapor pressure at room temperature is high enough, the provision of air aspiration may be sufficient to make drying unnecessary and allow the direct and immediate contact of the textile with the dyeing bath, if such dyeing bath contains only organic solvents and if the treatment of thermal fixing is achieved on dyed fabric. Of course this implies that there is compatibility between the solvents of the degreasing-desizing bath and the solvents of the dyeing bath.
If thermal fixing comes before dyeing, such fixing may also be effected without previous drying provided that the apparatus in which it is achieved is fitted with means to recover the organic solvents.
3. Water consumption and corresponding pollution are nonexistent.
4. Solvents may be regenerated, by means of distillation or any other method, and be recycled in a following operation. The solvent consumption is reduced by recovery operations and may easily be limited to about 5 percent.
5. To the savings of heat energy resulting from cold treatment and from drying suppression is added an important decreasing of labor cost owed to the quickness of treatment.
The system comprising solvent agent (pure or mixture) and alkaline agent may be applied to the textile material to be treated using the common means, that is:
either moving of liquid through the fixed textile material as is generally the case for cake threads, reels or hanks
or by moving of the textile substance in fixed liquid as it is generally the case for woven or knit fabrics treated on winch vessels, jiggers, course vats, pads, etc.
The process according to the invention may be applied with devices of common type, provided that metals and joints have a nature able to resist the solvents and that the conventional convenient measures are taken with regard to solvent vapors, so as to catch the vapor for a distillation recovery, and to maintain staff safety and buildings salubrity.
From the point of view of process exploitation it is very important to be able to easily control the results even when carried out by a nonspecialized staff, instead of under laboratory control, which is always possible but which takes a long time and, accordingly, does not allow in case of need of an immediate correction. Therefore a means of testing and control has now been developed using the property of polyacrylic acid to become nonsoluble under the effect of dry heat to immediately give a green coloration with the reagent known under the name of "Identex II" (furnished by the Society "Francaise des Matieres Colorantes").
For the polyacrylic acid, the critical temperature from which this green coloration is obtained on a nondesized fabric is 170° C.; this polymer is made nonsoluble by the heat necessarily applied for fiber thermal fixing. Consequently it is desirable to test, if, after desizing, there remains any polyacrylic acid which may be made nonsoluble by fixing treatment. From this point of view it has been discovered that by contacting the fabric to be tested with series of studs heated to temperatures having between them a gradation from 171° C. up to the upper temperature at which such treatment is achieved, it is possible to obtain a valuable quotation to measure desizing degree.
If, as an example, the fabric to be tested is a polyamide 6--6, which will subsequently be thermofixed at 210° C. and if the gradual series of studs has 4 of them between 171° C. and 213° C., for example 176°-183°-193°-204°, the number 1 can be assigned to the stud at 171°, 2 to 176°, 3 to 183°, 4 to 193°, 5 to 204° and 6 to 213°; and the desizing degree, quoted as numbers 1 to 6, will be obtained when Identex II is applied to a textile material, the green color appearing on the surface having been in contact with studs, 1,2,3,4,5 or 6 during equal times and pressures.
An easy way to achieve this test is to use an apparatus with studs of the "Thermotest" type built by the Firm ADAM, designed for the purpose of controlling sublimation resistance of dyes on synthetic fibers and having in a range of standardized temperatures the following values: 149°-154°-158°-161°-165°-171°-17 6°-183°-204°-213°-225°-229° C. Besides this apparatus has 5 scales of 13 temperatures, according to stud heating degree, that is:
for degree A of heating : 119° to 177°
" " B " : 129° to 194°
" " C " : 139° to 212°
" " D " : 149° to 229°
" " E " : 159° to 246°
So, it is possible to choose one of the scales (for example the scale D in the example quoted hereinbefore) and keep it with regard to synthetic fibers to be the most usually tested. Thus, to use this apparatus, it is sufficient to take from the desized fabric a strip of 6 cm. × 40 cm., to put it during 45 seconds in contact with the range of heated studs, from stud 171° up to 229°, to immerse the strip in an aqueous solution containing 1 g./1. of reagent "Identex" at 15° C.; to soap quickly in the hot, to rinse and to note from which stud the green color appears.
It is obvious that any device allowing a contact of a well-determined time under a determined pressure with hot surfaces of precise temperatures would fit as well as ADAM thermotest, which is indicated here only as an illustrative tester and because it is of great interest in units treating synthetic fabrics.
The following applications of the degreasing/desizing process according to the invention and of its control are indicated in the illustrative examples hereinafter.
EXAMPLE 1
The experimentation is made on a polyamide 6--6 taffeta of 95 g./m. 2 and the warp of which has a polyacrylic acid sizing at the rate of 1 to 2 percent of warp weight and the weft of which has a greasing with emulsified mineral oil at the rate of 1 percent of oil with regard to fabric weight. The dry unbleached fabric is passed at the speed of 100 m./min. in a pad with two rolls giving a squeezing ratio of 65 percent in a bath at 18° C. composed per 100 liters of:
70 l. of isopropanol
30 l. of tetrachlorethylene
300 gm. of solid potassium hydroxide
The fabric, wound at pad outlet, is stored in roll for 24 hr. at room temperature. Then it is rinsed at the speed of 15 m./min. in a roller-vat having a run of 5 m. in tetrachloroethylene maintained at the temperature of 80° C. The vat has at its outlet a squeeze device to remove solvent up to 80 percent. Then the fabric passes in a short stenter comprising a vaporization chamber maintained at the temperature necessary for solvent removing, provided with a device for solvent vapors catching and a thermofixing chamber maintained at 210°; the total duration of passage through the stenter does not exceed 2 min. The fabric wound at the stenter outlet is adapted for dyeing directly.
Desizing degree is controlled on a strip taken from the storage roll after the 24 hr. storage. This strip is rinsed hastily in a beaker containing tetrachlorethylene brought to 80° C., then dried, contacted during 1 minute with heated studs of an ADAM thermotest and at last immersed during 1 minute in the reagent "Identex II" at 15° C., then washed and rinsed.
Desizing degree quotation is 6 : consequently the degree of desizing is excellent.
EXAMPLE 2
A polyamide-6 linen of 80 g./m. 2 is wound in a closed jigger in which is introduced a 10 percent solution of piperidine in trichlorethylene.
Only one passing of the linen is achieved at a maximal speed in the bath at room temperature. The roll is extracted from jigger and stored during 24 hr. at room temperature while maintaining it in slow rotation.
Then the roll is circulated in a second closed jigger containing a trichlorinated ethylene bath maintained at 80°. Only one passage is made at maximum speed. The jigger has at its outlet a squeezing device followed by a short vaporization chamber with solvent vapor recovery, and winding at the outlet of the fabric preparatory for printing in turn followed with a thermal fixing.
The control achieved according to the same modalities as in example 1 is limited to quotation 3 for desizing, because the maximal temperature for polyamide 6 does not exceed 180° C. This is good desizing under the required conditions.
The above exemplifications of the invention are offered illustratively and modifications may be made without departing from the invention.