Title:
BLEACHING OF CELLULOSE CONTAINING TEXTILE FIBER MATERIAL WITH A SILICATE-FREE STABILIZED PEROXIDE BLEACHING BATH
United States Patent 3860391
Abstract:
Cellulose fibers or mixtures thereof with synthetic fibers, especially with polyester fibers, are advantageously bleached by means of peroxide or agents capable of splitting off peroxide by adding to a peroxide containing silicate-free bleaching bath as stabilizer amino lower alkylene polyphosphonates and/or hydroxy alkane phosphonates together with hydroxy compounds or polyhydroxy compounds having 2 to 6 carbon atoms in their carbon chain and, if required, with polyamino carboxylic acids. The process according to the present invention has the advantage that deposit formation on the bleaching equipment as well as on the bleached goods is considerably reduced. The decrease in the average degree of polymerization which always takes place on bleaching is less when using the bleaching bath according to the present invention than when using silicate-containing bleaching baths and the degree of whiteness is at least as high as that achieved with silicate-containing bleaching baths while the ash values are considerably reduced, in contrast to those obtained with said silicate-containing baths. When using the combination of phosphonic acid with hydroxy compounds or polyhydroxy compounds, the amount of phosphonic acid can be considerably reduced.
US Patent References:
Peroxide bleaching compositions and their use
Young - March 1960 - 2927082
Stabilization of peroxy solutions
Irani - February 1966 - 3234140
Liquid active oxygen detergent bleaching concentrate
Lindner et al. - June 1968 - 3388069
METHOD FOR UNIFORMING THE COLOR OF WOOD AND WOOD ARTICLES
Bailey et al. - February 1972 - 3645666
/3681022.html
Kibbel et al. - August 1972 - 3681022
Peroxide bleaching compositions and their use
Young - March 1960 - 2927082
Stabilization of peroxy solutions
Irani - February 1966 - 3234140
Liquid active oxygen detergent bleaching concentrate
Lindner et al. - June 1968 - 3388069
METHOD FOR UNIFORMING THE COLOR OF WOOD AND WOOD ARTICLES
Bailey et al. - February 1972 - 3645666
/3681022.html
Kibbel et al. - August 1972 - 3681022
Inventors:
Kling, Alfred (Ladenburg, DT)
Specht, Viktor (Dossenheim, DT)
Hofstetter, Carmen (Mannheim-Kaefertal, DT)
Eisenberg, Gundolf (Hemsbach, DT)
Specht, Viktor (Dossenheim, DT)
Hofstetter, Carmen (Mannheim-Kaefertal, DT)
Eisenberg, Gundolf (Hemsbach, DT)
Application Number:
05/338863
Publication Date:
01/14/1975
Filing Date:
03/07/1973
View Patent Images:
Export Citation:
Assignee:
Benckiser-Knapsack GmbH (Ladenburg Necker, DT)
Primary Class:
Other Classes:
252/186.250, 162/80, 987/160, 252/186.290, 162/77, 162/78, 162/76
International Classes:
C01B15/037; C07F9/40; D06L3/02; C01B15/00; C07F9/00; D06L3/00; D06L3/02
Field of Search:
162/78,76,80,77 423/272,584 260/52.4P,502.5 252/186,100 8/111
US Patent References:
Primary Examiner:
Lindsay Jr., Robert L.
Assistant Examiner:
Corbin, Arthur L.
Attorney, Agent or Firm:
Radde, Erich M. H.
Claims:
We claim
1. In a process of bleaching cellulose containing textile fiber material with a peroxide containing bleaching bath, the improvement which consists in
2. providing a peroxide-containing bleaching bath free of silicate and adjusted to a pH between about 9.0 and about 12.0;
3.
4. adding to said bath a stabilizing agent consisting of a mixture of
5. bleaching the cellulose-containing textile fiber material with said stabilizing agent containing bath without substantially reducing the degree of polymerization of the cellulose present in the fiber material.
6. The process of claim 1, in which the stabilizing agent is added to the bleaching bath in an amount between about 6 % and about 15 % calculated for 35% hydrogen peroxide present therein.
7. The process of claim 1 further comprising adding to the silicate-free hydrogen peroxide-containing bleaching bath, in addition to the stabilizing agent, a polyamino carboxylic acid.
8. The process of claim 1, in which the alkylene group of the stabilizing amino alkylene phosphonic acid has 1 to 6 carbon atoms.
9. The process of claim 1, in which the alkane group of the stabilizing hydroxy alkane phosphonic acid has 1 to 3 carbon atoms.
10. The process of claim 1, in which the stabilizing hydroxy compound is a compound selected from the group consisting of gluconic acid, citric acid, erythritol, pentaerythritol, sorbitol, and triethanolamine.
11. The process of claim 4, in which the polyamino carboxylic acid is an acid selected from the group consisting of ethylene diamino tetra-acetic acid, nitrilo tri-acetic acid, and diethylene triamino penta-acetic acid.
12. The process of claim 1, in which bleaching is effected at a temperature between about 110° C. and about 145° C.
13. The process of claim 1, in which the cellulose-containing textile fiber material is a fiber material containing cellulose fibers in mixture with synthetic fibers.
14. The process of claim 1, in which the cellulose-containing textile fiber material is a fiber material containing cellulose fibers in mixture with polyester fibers.
1. In a process of bleaching cellulose containing textile fiber material with a peroxide containing bleaching bath, the improvement which consists in
2. providing a peroxide-containing bleaching bath free of silicate and adjusted to a pH between about 9.0 and about 12.0;
3.
4. adding to said bath a stabilizing agent consisting of a mixture of
5. bleaching the cellulose-containing textile fiber material with said stabilizing agent containing bath without substantially reducing the degree of polymerization of the cellulose present in the fiber material.
6. The process of claim 1, in which the stabilizing agent is added to the bleaching bath in an amount between about 6 % and about 15 % calculated for 35% hydrogen peroxide present therein.
7. The process of claim 1 further comprising adding to the silicate-free hydrogen peroxide-containing bleaching bath, in addition to the stabilizing agent, a polyamino carboxylic acid.
8. The process of claim 1, in which the alkylene group of the stabilizing amino alkylene phosphonic acid has 1 to 6 carbon atoms.
9. The process of claim 1, in which the alkane group of the stabilizing hydroxy alkane phosphonic acid has 1 to 3 carbon atoms.
10. The process of claim 1, in which the stabilizing hydroxy compound is a compound selected from the group consisting of gluconic acid, citric acid, erythritol, pentaerythritol, sorbitol, and triethanolamine.
11. The process of claim 4, in which the polyamino carboxylic acid is an acid selected from the group consisting of ethylene diamino tetra-acetic acid, nitrilo tri-acetic acid, and diethylene triamino penta-acetic acid.
12. The process of claim 1, in which bleaching is effected at a temperature between about 110° C. and about 145° C.
13. The process of claim 1, in which the cellulose-containing textile fiber material is a fiber material containing cellulose fibers in mixture with synthetic fibers.
14. The process of claim 1, in which the cellulose-containing textile fiber material is a fiber material containing cellulose fibers in mixture with polyester fibers.
Description:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process of bleaching cellulose fibers and more particularly to an improved process of bleaching cellulose fibers or mixtures thereof with synthetic fibers, especially with polyester fibers, by means of bleaching compositions containing phosphonic acids, to a bleaching composition useful in said process, and to the resulting bleached cellulose fibers or mixtures thereof with synthetic fibers.
2. Description of the Prior Art
Cellulose fibers and especially cotton, linen, nettle, jute fibers are usually bleached by means of hydrogen peroxide or of compounds capable of splitting off of hydrogen peroxide. Bleaching is effected either in a long liquor with the goods to be bleached being placed, for instance, on reels or in a short liquor similar to the baths used in impregnating processes. Bleaching with hydrogen peroxide or the like can be carried out at a low temperature by the so-called cold bleaching process in which the goods to be bleached remain in the bleaching bath for a prolonged period of time. Shortening of the bleaching time has been achieved by heating the goods to be bleached and impregnated with the bleaching bath in an I-box or similar apparatus to a temperature up to 100° C.
Recently, a procedure has been suggested according to which the goods are bleached at a temperature between 100° C. and 145° C. Bleaching according to this so-called high temperature process results in a very considerable reduction of the bleaching time to between about 30 seconds and about 180 seconds.
While, when working in dilute bleaching baths, it has been recommended to use silicate-free stabilizers (German Published Application No. 1,021,823), it was not possible, heretofore, to omit addition of silicates to the impregnating bleaching bath, especially when proceeding according to the high temperature bleaching process. See, for instance, Meliand Textilberichte vol. 51, page 1,070 (1970) and the German provisionally published Application No. 1,519,484. Thereby, silicate deposits precipitated on the bleached goods and in the apparatus could not be avoided and had to be accepted in the course of operation.
In order to remove such silicate deposits on the bleaching apparatus, it was heretofore necessary to frequently interrupt the continuous bleaching procedure causing considerable economical disadvantages. Furthermore, the silicate precipitates have a highly disadvantageous effect upon the bleached goods as this is well known.
SUMMARY OF THE INVENTION
It is one object of the present invention to provide a simple and effective process of bleaching cellulose fibers or mixtures thereof with synthetic fibers which process avoids the disadvantages of the known bleaching processes.
Another object of the present invention is to provide a peroxide containing silicate-free bleaching composition for carrying out the new process of bleaching cellulose fibers and the like.
A further object of this invention is to provide cellulose fibers or their mixtures with synthetic fibers which have been bleached by the process according to the present invention.
In principle the process of the present invention which overcomes the disadvantages of the known processes mentioned hereinabove, comprises the addition of, as stabilizer, amino lower alkylene polyphosphonates and/or hydroxy lower alkane phosphonates together with aliphatic hydroxy or polyhydroxy compounds with 2 to 6 carbon atoms in their carbon chain and, if desired, with poly-amino carboxylic acids to the bleaching bath which contains, as bleaching agent, hydrogen peroxide or agents capable of splitting off hydrogen peroxide in the usual concentration.
Suitable amino lower alkylene phosphonic acids are those which are derived from aliphatic or alicyclic hydrocarbons containing 1 to 6 carbon atoms. Especially useful have proved to be amino di-(methylene phosphonic acid), amino tris-(methylene phosphonic acid), diethylene triamino penta-(methylene phosphonic acid), 1,2- or 1,3-propylidene diamino tetra-(methylene phosphonic acid), ethylene diamino tetra-(methylene phosphonic acid), 1,2-cyclohexane diamino tetra-(methylene phosphonic acid), 1-amino methyl cyclopentylamino-(2)-tetra-(methylene phosphonic acid).
Useful hydroxy alkane phosphonic acids are those which are dervied from aliphatic or alicyclic hydrocarbons having 1 to 4 carbon atoms. Especially suitable have proved to be hydroxy ethane-1,1-diphosphonic acid and 1-hydroxy propane-1,1,3-triphosphonic acid.
Hydroxy compounds or, respectively, polyhydroxy compounds, such as gluconic acid, citric acid, erythritol, pentaerythritol, sorbitol, and triethanolamine can be used advantageously.
Ethylene diamino tetra-acetic acid, diethylene triamino penta-acetic acid and nitrilo tri-acetic acid can be used as polyamino carboxylic acid additives.
The bleaching agent is preferably hydrogen peroxide in 30% to 35% solution. In place of hydrogen peroxide, there can also be used agents which are capable of splitting off oxygen. The amount of the stabilizer added is preferably within the range of 2% to 30% and most advantageously between 6% and 15% calculated for 35% hydrogen peroxide solution. Bleaching is carried out in an alkaline medium at a pH value between about 9.0 and 12.0. As a result of such an alkaline reaction the phosphonic acids are present in the bleaching bath in the form of their corresponding salts. Of course, it is also possible to add in place of the free acids their soluble salts and especially their alkali metal salts.
An especially noteworthy advantage of the bleaching process according to the present invention is to be seen in the fact that the decrease in the average degree of polymerization of the cellulose which always takes place on bleaching is less pronounced than, and the degree of whiteness is as high as, when using silicate-containing bleaching baths, but the ash content of the bleached cellulose is considerably lower.
Wetting agents can be added to the bleaching bath in order to effect more rapid wetting of the goods to be bleached. For this purpose all conventional wetting agents can be used which are effective in an alkaline medium and which are compatible with the phosphonic acid and the other components of the stabilizer addition. Suitable wetting agents are those of the anion-active and non-ionogenic wetting agent type as well as mixtures thereof. Preferred anion-active wetting agents are, for instance, alkyl aryl sulfonates, fatty acid condensation products, protein degradation products, and others as well as their salts. Non-ionogenic compounds are, for instance, the compounds obtained by addition of ethylene oxide to fatty alcohols, fatty acid amides, alkyl phenols, and others.
The bleaching process according to the present invention can be carried out at room temperature according to the cold bleaching process as well as at a higher temperature and especially according to the so-called high temperature process at temperatures exceeding 100° C. and preferably between 110° C. and 145° C. The proportion of phosphonic acid to the other components of the stabilizer can vary in wide limits. Excellent results are achieved by using compositions in which the proportion of phosphonic acid to the hydroxy compounds or, respectively, to the polyhydroxy compounds is between 1:1 and 10:1. The combination according to the present invention permits to keep the amount of phosphonic acid in the stabilizer relatively low, thus improving the economy of the process.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The following examples serve to illustrate the present invention without, however, limiting the same thereto.
Example 1
Pre-wetted crude cotton (squeezing effect: 60 %) is impregnated with the bleaching bath (squeezing effect: 100 %) in a conventional wide bleaching equipment of the Artos type. The impregnated cotton fabric is heated to 95° C. in a steam shaft oven and is bleached at said temperature for 30 minutes. The following impregnating baths were used for bleaching:
a. heretofore used bleaching bath:
4.0 g./l. of a wetting agent consisting of a mixture of a phenyl sulfonate with an ethoxylated fatty alcohol;
2.4 ml./l. of ethylene diamino tetra-acetic acid stabilizer;
24.0 ml./l. of waterglass solution 38° Be;
14.0 ml./l. of sodium hydroxide solution 50° Be;
35.0 ml./l. of 35% hydrogen peroxide solution.
b. Bleaching bath according to the present invention
4.0 g./l. of the same wetting agent as given under 1 (a),
8.0 ml./l. of sodium hydroxide solution 50° Be;
35.0 ml./l. of 35% hydrogen peroxide solution;
0.2 g./l. of diethylene triamino penta-(methylene phosphonic acid;
4.0 g./l. of gluconic acid;
0.4 g./l. of diethylene triamino penta-acetic acid.
Bleaching Results:
Degree of Ash whiteness content ______________________________________ Starting cotton fabric 50.7 -- Composition 1 a 84.5 0.37 Composition 1 b 83.7 0.19 ______________________________________
When carrying out the bleaching process with the composition of Example 1a, the bleaching equipment shows a very high deposit of silicate and the ash content of the bleached goods is relatively high.
In contrast thereto, no deposits were observed in the bleaching equipment, when bleaching with the composition 1b according to the present invention. The degree of whiteness was not essentially different from that on bleaching with the heretofore used composition 1a, but the ash content of the goods was reduced by about 50 %.
Example 2
Bucked cotton fabric was impregnated with the bleaching bath according to the present invention and was then heated in a pilot plant high temperature steaming equipment (Type Hoechst - System Kleinewefers) at 140° C. for 60 seconds. The bleached cotton fabric was subsequently washed with hot water and finally with cold water.
Composition of the bleaching bath:
1.5 g./l. of sodium hydroxide,
2.0 g./l. of the same wetting agent as used in Example 1 (a),
35.0 ml./l. of 35% hydrogen peroxide solution,
0.6g./l. of diethylene triamino penta-(methylene phosphonic acid),
5.4 g./l. of sorbitol,
1.2 g./l. of diethylene triamino penta-acetic acid.
Bleaching Results:
Degree of Degree of whiteness polymerization ______________________________________ Bucked cotton fabric 60.7 1980 Bleached cotton fabric 86.4 1600 ______________________________________
When using the bleaching composition according to the present invention, a highly satisfactory degree of whiteness is produced, while the degree of polymerization considerably exceeds that usually achieved on bleaching with peroxide. The degree of polymerization was determined according to the Cuoxam-method described, for instance, by J. J. Riphagen in "Melliand Textilberichte" 1971, pp. 133-136.
Example 3
Cotton fabric was bleached at 85° C. in an AHIBA-type laboratory equipment with a proportion of fabric to bath of 1:40 for 1 hour. The active oxygen content of the bleaching bath was determined in samples taken from the bath by titration according to the iodide-thiosulfate method. Tap water of 17° German hardness was used for preparing the bleaching bath. In a second test 4 mg./l. of ferric ions were added. Bleaching was effected with the following bleaching bath:
Bleaching bath 3a:
4.0 ml./l. of sodium hydroxide solution 38° Be,
5.0 ml./l. of 30% hydrogen peroxide solution,
0.2 g./l. of ethylene diamino tetra-acetic acid,
0.7 g./l. of sodium tripolyphosphate.
Bleaching bath 3b (according to the present invention:
4.0 ml./l. of sodium hydroxide solution 38° Be,
5.0 ml./l. of 30% hydrogen peroxide solution,
0.2 g./l. of ethylene diamino tetra-(methylene phosphonic acid),
0.2 g./l. of gluconic acid.
The attached graphs of FIGS. 1 and 2 illustrate the results achieved with the above-indicated bleaching baths. In these graphs there is plotted the amount of activated oxygen in mg. per 100 ml. of bleaching bath (ordinate), while the symbols given on the abscissa represent the following data:
T o = at the beginning of the bleaching process,
T 1 = at 40° C.,
T 2 = at 85° C.,
T 3 = at 85° C. after 20 minutes,
T 4 = at 85° C. after 40 minutes,
T 5 = at 85° C. after 60 minutes.
It is evident from the curves of FIG. 1 illustrating the activated oxygen content in the bleaching bath, that the oxygen content very rapidly decreases as soon as a temperature of 85° C. is attained. The solid line indicates the values obtained without the addition of ferric ions while the dotted line illustrates the results achieved when adding ferric ions to the bleaching bath. It follows that the oxygen decomposition is even more pronounced in the presence of ferric ions. In both tests with or without ferric ions, i.e., when using a bleaching bath according to the prior art, insufficient stabilization was achieved. As a result thereof, the degree of whiteness was only 78.1 or, respectively, 73.2 (in the presence of ferric ions). The degree of whiteness was determined with the Filter R 46 by means of the Elepho device.
The "Elrepho apparatus with filter R 46" used for determining the degree of whiteness is an electric remission photometer of the firm Carl Zeiss with a band elimination filter having its optimum transmission at 460 nm.
In contrast to these results the activated oxygen content of the bleaching bath 3b according to the present invention as shown by the solid line curve of FIG. 2 was diminished only to an extent corresponding to the actual consumption of oxygen due to the bleaching effect. In the presence of ferric ions as indicated by the dotted line curve of FIG. 2, the decrease in activated oxygen was slightly greater but still within such limits as they correspond to an ideal bleaching procedure. This is clearly demonstrated by the degree of whiteness of 80.0 or, respectively, 81.5 in the presence of ferric ions.
Example 4
15.0 g. of desized cotton fabric were bleached with the compositions given hereinafter in a laboratory equipment of the "Multicolor" type of the firm Pretema A.G. whereby the proportion of fabric to bleaching bath was 1:30, after heating the fabric in said bath to a temperature of 125° C. within 30 minutes and then continuing heating at said temperature for 30 more minutes. The water used for preparing the bleaching bath corresponds to a magnesium hardness of 5° German hardness. The residual oxygen content of the baths was determined after the test was completed.
Composition 4A:
5.0 ml./l. of 30% hydrogen peroxide,
x ml./l. of sodium hydroxide solution sufficient to adjust the bleaching bath to a pH of 12.0,
0.14 g./l. of diethylene triamino penta-(methylene phosphonic acid),
0.08 g./l. of diethylene triamino penta-acetic acid,
0.22 g./l. of gluconic acid.
Composition 4b (conventional bleaching bath): 5.0 ml./l. of 30% hydrogen peroxide solution,
x ml./l. of sodium hydroxide solution sufficient to adjust the bleaching bath to a pH of 12.0,
6.67 ml./l. of waterglass solution 38° Be,
Bleaching Results:
Degree of Degree Ash Residual polymeri- of con- oxygen zation whiteness tent ______________________________________ Starting fabric 1840 58.6 1.0 -- Composition 4a 1760 76.0 0.27 73 % Composition 4b 1720 80.5 0.60 58.5 % ______________________________________
In another test bleaching was effected as described hereinabove with the following compositions and with the addition of 4 mg./l. of ferric ions to each bleaching bath.
Composition 4 c:
5 ml./l. of 30% hydrogen peroxide solution
x ml./l. of sodium hydroxide solution sufficient to adjust the pH-value of the bleaching bath to a pH of 12.0,
1.0 g./l. of 1-hydroxy propane-1,1,3-triphosphonic acid.
Composition 4 d:
5.0 ml./l. of 30% hydrogen peroxide solution,
x ml./l. of sodium hydroxide solution sufficient to adjust the pH-value of the bleaching bath to a pH of 12.0,
6.67 ml./l. of waterglass solution 30° Be.
Bleaching Results:
Degree of Degree Ash Residual polymeri- of con- oxygen zation whiteness tent ______________________________________ Starting fabric 1840 58.6 1 % -- Composition 4 c 1800 79.4 0.25% 60 % Composition 4 d 1690 80.9 0.51% 57 % ______________________________________
The above given data clearly show that, when using the silicate-free stabilizers according to the present invention low ash contents and a satisfactory degree of polymerization are achieved on working under high temperature condition, whereby the degree of whiteness is about the same as that achieved on bleaching with the addition of silicate. Furthermore, these tests demonstrate that, when using the phosphonic acid alone, a considerably higher amount thereof must be used than when using its combination with hydroxy compounds or, respectively, polyhydroxy compounds.
In place of the amino alkylene phosphonic acids used in the preceding examples, there may be employed corresponding amounts of other amino alkylene phosphonic acids and/or hydroxy alkane phosphonic acids. In general, suitable amino alkylene phosphonic acids correspond to the following Formula I ##SPC1##
In said Formula R 1 and R 2 indicate the following groups and atoms:
a. R 1 and R 2 indicate groups of the Formula ##SPC2##
b. R 1 indicates the group of the Formula ##SPC3##
R 2 indicates a group of the Formula ##SPC4##
wherein
x indicates the numerals 2 and 3;
y indicates the numerals 0 to 4; while
R and R 3 both are the group of the Formula ##SPC5##
one of R and R 3 is the group of the Formula ##SPC6##
and the other one is hydrogen or both R and R 3 indicate hydrogen; or
c. R 1 indicates the group of the Formula ##SPC7##
R 2 indicates the group of the Formula ##SPC8##
wherein
R 4 indicates hydrogen or hydroxyl and R 5 indicates hydrogen or alkyl, especially lower alkyl, such as methyl or ethyl; or
R 4 and R 5 together with the two carbon atoms to which they are attached, form a cycloalkyl ring, preferably with four to six carbon atoms such as cyclobutyl, cyclopentyl, or cyclohexyl, while
o and z indicate one of the numerals 0 and 1, and R 6 indicates hydrogen or the group of the Formula ##SPC9##
d. the group of the Formula ##SPC10##
in which
m and n are one of the numerals 1 to 3.
In general, suitable hydroxy alkane diphosphonic acids correspond to the following Formula II: ##SPC11##
in which
R 8 is hydrogen, hydroxyl, the amino group, a lower alkylamino group, a di-lower alkyl amino group, or lower alkyl with 1 to 8 carbon atoms, and
R 9 is hydrogen or lower alkyl with 1 to 10 carbon atoms.
In place of the amino alkylene phosphonic acids and hydroxyalkane diphosphonic acids mentioned hereinabove and used in the Examples, there can be employed the following acids, although the present invention is not limited thereto:
Dipropylene triamino penta-(methylene phosphonic acid),
1,3-diamino-2-propanol tetra-(methylene phosphonic acid),
1,2-bis-(amino methyl) cyclobutane tetra-(methylene phosphonic acid),
amino tris-(ethylidene phosphonic acid),
amino tris-(isopropylidene phosphonic acid),
diamino diethyl sulfido tetra-(methylene phosphonic acid),
1-amino ethane-1,1-diphosphonic acid,
1-hydroxy ethane-1,1,2-triphosphonic acid,
1,3-diamino-2-propanol tetra-(methylene phosphonic acid),
and others. Mixtures of such phosphonic acids can, of course, also be used.
In place of the hydroxy compounds or, respectively, polyhydroxy compounds mentioned hereinabove and used in the Examples, there can also be employed tartaric acid, malic acid, glucuronic acid, and others.
In place of the polyamino carboxylic acid additives mentioned hereinabove and used in the Examples, there can be employed N-hydroxy ethyl ethylene diamino tri-acetic acid, N,N-(2-hydroxy ethyl) glycine, 1,3-diamino-2-propanol tetra-acetic acid, and others.
As stated hereinabove, the preferred bleaching agent is hydrogen peroxide which is used, depending upon the proportion of goods to be bleached to bleaching bath, in a concentration in the bleaching bath between about 1 g./l. and about 35 g./l. and preferably between about 3 g./l. and about 15 g./l. calculated for 100 % hydrogen peroxide. In place of hydrogen peroxide, there can also be employed alkali metal peroxides such as sodium peroxide, alkali metal perborates, percarbonates, or perphosphates. The preferred bleaching agent, however, is hydrogen peroxide.
It has been pointed out hereinabove in Example 1, that when adding water glass to the bleaching bath, the bleaching equipment must be cleaned and bleaching must be interrupted every 8 to 14 days in order to remove silicate deposits on the bleaching equipment. Usually this interruption lasts for 3 to 8 hours. In contrast thereto, when bleaching with a bleaching bath according to the present invention, no such repeated and time consuming cleaning of the equipment is required.
It may also be mentioned that when bleaching with a hydrogen peroxide bath but without the addition of the stabilizing agent according to the present invention, the degree of polymerization is reduced, for instance, when proceeding according to Example 2, to a value of about 1,000, i.e., to only about 50 % of the initial degree of polymerization of the fabric to be bleached.
The ferric ions are added, for instance, in Examples 3 and 4 in the form of ferric chloride.
Of course, many changes and variations in the bleaching procedure and the bleaching bath composition and the like may be made by those skilled in the art in accordance with the principles set forth hereinabove and in the claims annexed hereto.
1. Field of the Invention
The present invention relates to a process of bleaching cellulose fibers and more particularly to an improved process of bleaching cellulose fibers or mixtures thereof with synthetic fibers, especially with polyester fibers, by means of bleaching compositions containing phosphonic acids, to a bleaching composition useful in said process, and to the resulting bleached cellulose fibers or mixtures thereof with synthetic fibers.
2. Description of the Prior Art
Cellulose fibers and especially cotton, linen, nettle, jute fibers are usually bleached by means of hydrogen peroxide or of compounds capable of splitting off of hydrogen peroxide. Bleaching is effected either in a long liquor with the goods to be bleached being placed, for instance, on reels or in a short liquor similar to the baths used in impregnating processes. Bleaching with hydrogen peroxide or the like can be carried out at a low temperature by the so-called cold bleaching process in which the goods to be bleached remain in the bleaching bath for a prolonged period of time. Shortening of the bleaching time has been achieved by heating the goods to be bleached and impregnated with the bleaching bath in an I-box or similar apparatus to a temperature up to 100° C.
Recently, a procedure has been suggested according to which the goods are bleached at a temperature between 100° C. and 145° C. Bleaching according to this so-called high temperature process results in a very considerable reduction of the bleaching time to between about 30 seconds and about 180 seconds.
While, when working in dilute bleaching baths, it has been recommended to use silicate-free stabilizers (German Published Application No. 1,021,823), it was not possible, heretofore, to omit addition of silicates to the impregnating bleaching bath, especially when proceeding according to the high temperature bleaching process. See, for instance, Meliand Textilberichte vol. 51, page 1,070 (1970) and the German provisionally published Application No. 1,519,484. Thereby, silicate deposits precipitated on the bleached goods and in the apparatus could not be avoided and had to be accepted in the course of operation.
In order to remove such silicate deposits on the bleaching apparatus, it was heretofore necessary to frequently interrupt the continuous bleaching procedure causing considerable economical disadvantages. Furthermore, the silicate precipitates have a highly disadvantageous effect upon the bleached goods as this is well known.
SUMMARY OF THE INVENTION
It is one object of the present invention to provide a simple and effective process of bleaching cellulose fibers or mixtures thereof with synthetic fibers which process avoids the disadvantages of the known bleaching processes.
Another object of the present invention is to provide a peroxide containing silicate-free bleaching composition for carrying out the new process of bleaching cellulose fibers and the like.
A further object of this invention is to provide cellulose fibers or their mixtures with synthetic fibers which have been bleached by the process according to the present invention.
In principle the process of the present invention which overcomes the disadvantages of the known processes mentioned hereinabove, comprises the addition of, as stabilizer, amino lower alkylene polyphosphonates and/or hydroxy lower alkane phosphonates together with aliphatic hydroxy or polyhydroxy compounds with 2 to 6 carbon atoms in their carbon chain and, if desired, with poly-amino carboxylic acids to the bleaching bath which contains, as bleaching agent, hydrogen peroxide or agents capable of splitting off hydrogen peroxide in the usual concentration.
Suitable amino lower alkylene phosphonic acids are those which are derived from aliphatic or alicyclic hydrocarbons containing 1 to 6 carbon atoms. Especially useful have proved to be amino di-(methylene phosphonic acid), amino tris-(methylene phosphonic acid), diethylene triamino penta-(methylene phosphonic acid), 1,2- or 1,3-propylidene diamino tetra-(methylene phosphonic acid), ethylene diamino tetra-(methylene phosphonic acid), 1,2-cyclohexane diamino tetra-(methylene phosphonic acid), 1-amino methyl cyclopentylamino-(2)-tetra-(methylene phosphonic acid).
Useful hydroxy alkane phosphonic acids are those which are dervied from aliphatic or alicyclic hydrocarbons having 1 to 4 carbon atoms. Especially suitable have proved to be hydroxy ethane-1,1-diphosphonic acid and 1-hydroxy propane-1,1,3-triphosphonic acid.
Hydroxy compounds or, respectively, polyhydroxy compounds, such as gluconic acid, citric acid, erythritol, pentaerythritol, sorbitol, and triethanolamine can be used advantageously.
Ethylene diamino tetra-acetic acid, diethylene triamino penta-acetic acid and nitrilo tri-acetic acid can be used as polyamino carboxylic acid additives.
The bleaching agent is preferably hydrogen peroxide in 30% to 35% solution. In place of hydrogen peroxide, there can also be used agents which are capable of splitting off oxygen. The amount of the stabilizer added is preferably within the range of 2% to 30% and most advantageously between 6% and 15% calculated for 35% hydrogen peroxide solution. Bleaching is carried out in an alkaline medium at a pH value between about 9.0 and 12.0. As a result of such an alkaline reaction the phosphonic acids are present in the bleaching bath in the form of their corresponding salts. Of course, it is also possible to add in place of the free acids their soluble salts and especially their alkali metal salts.
An especially noteworthy advantage of the bleaching process according to the present invention is to be seen in the fact that the decrease in the average degree of polymerization of the cellulose which always takes place on bleaching is less pronounced than, and the degree of whiteness is as high as, when using silicate-containing bleaching baths, but the ash content of the bleached cellulose is considerably lower.
Wetting agents can be added to the bleaching bath in order to effect more rapid wetting of the goods to be bleached. For this purpose all conventional wetting agents can be used which are effective in an alkaline medium and which are compatible with the phosphonic acid and the other components of the stabilizer addition. Suitable wetting agents are those of the anion-active and non-ionogenic wetting agent type as well as mixtures thereof. Preferred anion-active wetting agents are, for instance, alkyl aryl sulfonates, fatty acid condensation products, protein degradation products, and others as well as their salts. Non-ionogenic compounds are, for instance, the compounds obtained by addition of ethylene oxide to fatty alcohols, fatty acid amides, alkyl phenols, and others.
The bleaching process according to the present invention can be carried out at room temperature according to the cold bleaching process as well as at a higher temperature and especially according to the so-called high temperature process at temperatures exceeding 100° C. and preferably between 110° C. and 145° C. The proportion of phosphonic acid to the other components of the stabilizer can vary in wide limits. Excellent results are achieved by using compositions in which the proportion of phosphonic acid to the hydroxy compounds or, respectively, to the polyhydroxy compounds is between 1:1 and 10:1. The combination according to the present invention permits to keep the amount of phosphonic acid in the stabilizer relatively low, thus improving the economy of the process.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The following examples serve to illustrate the present invention without, however, limiting the same thereto.
Example 1
Pre-wetted crude cotton (squeezing effect: 60 %) is impregnated with the bleaching bath (squeezing effect: 100 %) in a conventional wide bleaching equipment of the Artos type. The impregnated cotton fabric is heated to 95° C. in a steam shaft oven and is bleached at said temperature for 30 minutes. The following impregnating baths were used for bleaching:
a. heretofore used bleaching bath:
4.0 g./l. of a wetting agent consisting of a mixture of a phenyl sulfonate with an ethoxylated fatty alcohol;
2.4 ml./l. of ethylene diamino tetra-acetic acid stabilizer;
24.0 ml./l. of waterglass solution 38° Be;
14.0 ml./l. of sodium hydroxide solution 50° Be;
35.0 ml./l. of 35% hydrogen peroxide solution.
b. Bleaching bath according to the present invention
4.0 g./l. of the same wetting agent as given under 1 (a),
8.0 ml./l. of sodium hydroxide solution 50° Be;
35.0 ml./l. of 35% hydrogen peroxide solution;
0.2 g./l. of diethylene triamino penta-(methylene phosphonic acid;
4.0 g./l. of gluconic acid;
0.4 g./l. of diethylene triamino penta-acetic acid.
Bleaching Results:
Degree of Ash whiteness content ______________________________________ Starting cotton fabric 50.7 -- Composition 1 a 84.5 0.37 Composition 1 b 83.7 0.19 ______________________________________
When carrying out the bleaching process with the composition of Example 1a, the bleaching equipment shows a very high deposit of silicate and the ash content of the bleached goods is relatively high.
In contrast thereto, no deposits were observed in the bleaching equipment, when bleaching with the composition 1b according to the present invention. The degree of whiteness was not essentially different from that on bleaching with the heretofore used composition 1a, but the ash content of the goods was reduced by about 50 %.
Example 2
Bucked cotton fabric was impregnated with the bleaching bath according to the present invention and was then heated in a pilot plant high temperature steaming equipment (Type Hoechst - System Kleinewefers) at 140° C. for 60 seconds. The bleached cotton fabric was subsequently washed with hot water and finally with cold water.
Composition of the bleaching bath:
1.5 g./l. of sodium hydroxide,
2.0 g./l. of the same wetting agent as used in Example 1 (a),
35.0 ml./l. of 35% hydrogen peroxide solution,
0.6g./l. of diethylene triamino penta-(methylene phosphonic acid),
5.4 g./l. of sorbitol,
1.2 g./l. of diethylene triamino penta-acetic acid.
Bleaching Results:
Degree of Degree of whiteness polymerization ______________________________________ Bucked cotton fabric 60.7 1980 Bleached cotton fabric 86.4 1600 ______________________________________
When using the bleaching composition according to the present invention, a highly satisfactory degree of whiteness is produced, while the degree of polymerization considerably exceeds that usually achieved on bleaching with peroxide. The degree of polymerization was determined according to the Cuoxam-method described, for instance, by J. J. Riphagen in "Melliand Textilberichte" 1971, pp. 133-136.
Example 3
Cotton fabric was bleached at 85° C. in an AHIBA-type laboratory equipment with a proportion of fabric to bath of 1:40 for 1 hour. The active oxygen content of the bleaching bath was determined in samples taken from the bath by titration according to the iodide-thiosulfate method. Tap water of 17° German hardness was used for preparing the bleaching bath. In a second test 4 mg./l. of ferric ions were added. Bleaching was effected with the following bleaching bath:
Bleaching bath 3a:
4.0 ml./l. of sodium hydroxide solution 38° Be,
5.0 ml./l. of 30% hydrogen peroxide solution,
0.2 g./l. of ethylene diamino tetra-acetic acid,
0.7 g./l. of sodium tripolyphosphate.
Bleaching bath 3b (according to the present invention:
4.0 ml./l. of sodium hydroxide solution 38° Be,
5.0 ml./l. of 30% hydrogen peroxide solution,
0.2 g./l. of ethylene diamino tetra-(methylene phosphonic acid),
0.2 g./l. of gluconic acid.
The attached graphs of FIGS. 1 and 2 illustrate the results achieved with the above-indicated bleaching baths. In these graphs there is plotted the amount of activated oxygen in mg. per 100 ml. of bleaching bath (ordinate), while the symbols given on the abscissa represent the following data:
T o = at the beginning of the bleaching process,
T 1 = at 40° C.,
T 2 = at 85° C.,
T 3 = at 85° C. after 20 minutes,
T 4 = at 85° C. after 40 minutes,
T 5 = at 85° C. after 60 minutes.
It is evident from the curves of FIG. 1 illustrating the activated oxygen content in the bleaching bath, that the oxygen content very rapidly decreases as soon as a temperature of 85° C. is attained. The solid line indicates the values obtained without the addition of ferric ions while the dotted line illustrates the results achieved when adding ferric ions to the bleaching bath. It follows that the oxygen decomposition is even more pronounced in the presence of ferric ions. In both tests with or without ferric ions, i.e., when using a bleaching bath according to the prior art, insufficient stabilization was achieved. As a result thereof, the degree of whiteness was only 78.1 or, respectively, 73.2 (in the presence of ferric ions). The degree of whiteness was determined with the Filter R 46 by means of the Elepho device.
The "Elrepho apparatus with filter R 46" used for determining the degree of whiteness is an electric remission photometer of the firm Carl Zeiss with a band elimination filter having its optimum transmission at 460 nm.
In contrast to these results the activated oxygen content of the bleaching bath 3b according to the present invention as shown by the solid line curve of FIG. 2 was diminished only to an extent corresponding to the actual consumption of oxygen due to the bleaching effect. In the presence of ferric ions as indicated by the dotted line curve of FIG. 2, the decrease in activated oxygen was slightly greater but still within such limits as they correspond to an ideal bleaching procedure. This is clearly demonstrated by the degree of whiteness of 80.0 or, respectively, 81.5 in the presence of ferric ions.
Example 4
15.0 g. of desized cotton fabric were bleached with the compositions given hereinafter in a laboratory equipment of the "Multicolor" type of the firm Pretema A.G. whereby the proportion of fabric to bleaching bath was 1:30, after heating the fabric in said bath to a temperature of 125° C. within 30 minutes and then continuing heating at said temperature for 30 more minutes. The water used for preparing the bleaching bath corresponds to a magnesium hardness of 5° German hardness. The residual oxygen content of the baths was determined after the test was completed.
Composition 4A:
5.0 ml./l. of 30% hydrogen peroxide,
x ml./l. of sodium hydroxide solution sufficient to adjust the bleaching bath to a pH of 12.0,
0.14 g./l. of diethylene triamino penta-(methylene phosphonic acid),
0.08 g./l. of diethylene triamino penta-acetic acid,
0.22 g./l. of gluconic acid.
Composition 4b (conventional bleaching bath): 5.0 ml./l. of 30% hydrogen peroxide solution,
x ml./l. of sodium hydroxide solution sufficient to adjust the bleaching bath to a pH of 12.0,
6.67 ml./l. of waterglass solution 38° Be,
Bleaching Results:
Degree of Degree Ash Residual polymeri- of con- oxygen zation whiteness tent ______________________________________ Starting fabric 1840 58.6 1.0 -- Composition 4a 1760 76.0 0.27 73 % Composition 4b 1720 80.5 0.60 58.5 % ______________________________________
In another test bleaching was effected as described hereinabove with the following compositions and with the addition of 4 mg./l. of ferric ions to each bleaching bath.
Composition 4 c:
5 ml./l. of 30% hydrogen peroxide solution
x ml./l. of sodium hydroxide solution sufficient to adjust the pH-value of the bleaching bath to a pH of 12.0,
1.0 g./l. of 1-hydroxy propane-1,1,3-triphosphonic acid.
Composition 4 d:
5.0 ml./l. of 30% hydrogen peroxide solution,
x ml./l. of sodium hydroxide solution sufficient to adjust the pH-value of the bleaching bath to a pH of 12.0,
6.67 ml./l. of waterglass solution 30° Be.
Bleaching Results:
Degree of Degree Ash Residual polymeri- of con- oxygen zation whiteness tent ______________________________________ Starting fabric 1840 58.6 1 % -- Composition 4 c 1800 79.4 0.25% 60 % Composition 4 d 1690 80.9 0.51% 57 % ______________________________________
The above given data clearly show that, when using the silicate-free stabilizers according to the present invention low ash contents and a satisfactory degree of polymerization are achieved on working under high temperature condition, whereby the degree of whiteness is about the same as that achieved on bleaching with the addition of silicate. Furthermore, these tests demonstrate that, when using the phosphonic acid alone, a considerably higher amount thereof must be used than when using its combination with hydroxy compounds or, respectively, polyhydroxy compounds.
In place of the amino alkylene phosphonic acids used in the preceding examples, there may be employed corresponding amounts of other amino alkylene phosphonic acids and/or hydroxy alkane phosphonic acids. In general, suitable amino alkylene phosphonic acids correspond to the following Formula I ##SPC1##
In said Formula R 1 and R 2 indicate the following groups and atoms:
a. R 1 and R 2 indicate groups of the Formula ##SPC2##
b. R 1 indicates the group of the Formula ##SPC3##
R 2 indicates a group of the Formula ##SPC4##
wherein
x indicates the numerals 2 and 3;
y indicates the numerals 0 to 4; while
R and R 3 both are the group of the Formula ##SPC5##
one of R and R 3 is the group of the Formula ##SPC6##
and the other one is hydrogen or both R and R 3 indicate hydrogen; or
c. R 1 indicates the group of the Formula ##SPC7##
R 2 indicates the group of the Formula ##SPC8##
wherein
R 4 indicates hydrogen or hydroxyl and R 5 indicates hydrogen or alkyl, especially lower alkyl, such as methyl or ethyl; or
R 4 and R 5 together with the two carbon atoms to which they are attached, form a cycloalkyl ring, preferably with four to six carbon atoms such as cyclobutyl, cyclopentyl, or cyclohexyl, while
o and z indicate one of the numerals 0 and 1, and R 6 indicates hydrogen or the group of the Formula ##SPC9##
d. the group of the Formula ##SPC10##
in which
m and n are one of the numerals 1 to 3.
In general, suitable hydroxy alkane diphosphonic acids correspond to the following Formula II: ##SPC11##
in which
R 8 is hydrogen, hydroxyl, the amino group, a lower alkylamino group, a di-lower alkyl amino group, or lower alkyl with 1 to 8 carbon atoms, and
R 9 is hydrogen or lower alkyl with 1 to 10 carbon atoms.
In place of the amino alkylene phosphonic acids and hydroxyalkane diphosphonic acids mentioned hereinabove and used in the Examples, there can be employed the following acids, although the present invention is not limited thereto:
Dipropylene triamino penta-(methylene phosphonic acid),
1,3-diamino-2-propanol tetra-(methylene phosphonic acid),
1,2-bis-(amino methyl) cyclobutane tetra-(methylene phosphonic acid),
amino tris-(ethylidene phosphonic acid),
amino tris-(isopropylidene phosphonic acid),
diamino diethyl sulfido tetra-(methylene phosphonic acid),
1-amino ethane-1,1-diphosphonic acid,
1-hydroxy ethane-1,1,2-triphosphonic acid,
1,3-diamino-2-propanol tetra-(methylene phosphonic acid),
and others. Mixtures of such phosphonic acids can, of course, also be used.
In place of the hydroxy compounds or, respectively, polyhydroxy compounds mentioned hereinabove and used in the Examples, there can also be employed tartaric acid, malic acid, glucuronic acid, and others.
In place of the polyamino carboxylic acid additives mentioned hereinabove and used in the Examples, there can be employed N-hydroxy ethyl ethylene diamino tri-acetic acid, N,N-(2-hydroxy ethyl) glycine, 1,3-diamino-2-propanol tetra-acetic acid, and others.
As stated hereinabove, the preferred bleaching agent is hydrogen peroxide which is used, depending upon the proportion of goods to be bleached to bleaching bath, in a concentration in the bleaching bath between about 1 g./l. and about 35 g./l. and preferably between about 3 g./l. and about 15 g./l. calculated for 100 % hydrogen peroxide. In place of hydrogen peroxide, there can also be employed alkali metal peroxides such as sodium peroxide, alkali metal perborates, percarbonates, or perphosphates. The preferred bleaching agent, however, is hydrogen peroxide.
It has been pointed out hereinabove in Example 1, that when adding water glass to the bleaching bath, the bleaching equipment must be cleaned and bleaching must be interrupted every 8 to 14 days in order to remove silicate deposits on the bleaching equipment. Usually this interruption lasts for 3 to 8 hours. In contrast thereto, when bleaching with a bleaching bath according to the present invention, no such repeated and time consuming cleaning of the equipment is required.
It may also be mentioned that when bleaching with a hydrogen peroxide bath but without the addition of the stabilizing agent according to the present invention, the degree of polymerization is reduced, for instance, when proceeding according to Example 2, to a value of about 1,000, i.e., to only about 50 % of the initial degree of polymerization of the fabric to be bleached.
The ferric ions are added, for instance, in Examples 3 and 4 in the form of ferric chloride.
Of course, many changes and variations in the bleaching procedure and the bleaching bath composition and the like may be made by those skilled in the art in accordance with the principles set forth hereinabove and in the claims annexed hereto.