FR2643093A1 - Improved processes for oxidising bleaching of cellulose fibres - Google Patents

Abstract

Treatment of cellulose fibres. The invention relates more particularly to an improved process for bleaching cellulose fibres, carried out in alkaline conditions with the aid of a peroxide in the presence of an alkali metal silicate, characterised in that the bleaching bath additionally contains an aminopolyphosphonic acid and is devoid of alkaline-earth metal ions, and to a composition suitable for making use of this process. Use in the textile, paratextile or paper industry.

Description

 The subject of the present invention is an improvement to the bleaching processes carried out using hydrogen peroxide or alkali metal peroxides on the various cellulosic fibers used in the textile, para-textile or paper industry.

 Depending on the fiber or material available, oxidative bleaching can be carried out in different ways. We operate, for example; discontinuously in a large volume of bath or continuously, at temperatures which can vary between 20 and 130-C.

 The implementation of a bleaching process using a peroxide also generally requires the use of a stabilizing agent in order to regulate the progress of the oxidizing process during bleaching.

 It is known that the use of alkaline earth ions, in particular, of magnesium ions, makes it possible to stabilize the bleaching baths based on a peroxide. Many magnesium compounds, salts or complexes have for example been recommended in order to stabilize the bleaching baths. The use of silicate or various magnesium complexes, such as those of EDTA, DTPA, NTA or phosphonic acids, is for example known.

 It is observed however that if the compounds and salts of alkaline earth metals, in particular of magnesium, make it possible to stabilize the peroxide baths, they do not, on the other hand, make it possible to improve the activation or the whitening power of the oxidizing solutions. Only the use of complexes and especially that of magnesium silicate makes it possible to obtain both a stabilizing and activating effect on the peroxide baths. With this in mind, the Applicant has described, in French patent No. 77. 20721, the production and use of concentrated solutions consisting of sodium silicate and a magnesium complex of a phosphonic acid.

The presence of alkaline earth endowments in a bath is however not without raising a certain number of difficulties during the various operations. Among the disadvantages encountered, we can for example cite
at. The insolubility of magnesium silicates causing scaling of the apparatuses or a spite on the fibers resulting in a modification of the touch of the bleached articles.

 b. Their incompatibility with certain direct dyes leading to significant modifications of the dyeing characteristics when the bleaching and dyeing are carried out in the same bath.

 vs. Their incompatibility in the case of dyes produced with reactive dyes when bleaching and dyeing are carried out in the same bath, without intermediate rinsing.

 d. Instability of bleaching baths when bleaching is carried out in the presence of softening agents.

The use of alkali metal compounds such as Na or K silicates, Na or K complexes of EDTA,
DTPA, NTA, or the Na or K salts of hydroxyalkane-phosphonic acids derived, for example, from C1 to C4 hydrocarbons, does not stabilize the bleaching baths based on peroxide.

The Applicant has now found that the use of alkali metal salts of amino polyphosphonic acids makes it possible to stabilize baths based on peroxides in the absence of alkaline earth metal compounds. It has also appeared that the introduction of an aminopolyphosphonic acid can be carried out in concentrated solutions of alkali metal silicates, leading to stable solutions which offer, compared to the use of compounds of alkaline earth metals, following advantages:
- excellent stability of the bleaching baths, making it possible in particular to avoid any offset of alkaline earth silicate
- an excellent stabilizing and activating effect making it possible to increase the degree of whiteness of the treated fibers.

 The present invention therefore relates to an improved process for bleaching cellulosic fibers carried out, under alkaline conditions, using a peroxide in the presence of an alkali metal silicate, characterized in that the bleaching bath contains in addition, an amino-polyphosphonic acid and is devoid of alkaline earth ions.

By "alkali metal silicate" is meant the silicates of Na or K. Usually the silicates of
Na or K will be used in the form of aqueous solutions whose SiO2 content is between 20 and 30% approximately, since these silicates are generally marketed in this form.

ou Rl et R2 sont chacun un radical alkylène en C1 -C6, de préférence en Cl-Cz ,
les acides 1. 2-cyclohéxane-tBtrakis- alkylènephosphoniques de la formule générale

où R3 est un radical alkylène en C-C6, de préférence en C1 t
les acides amino-trialkylenephosphoniques de la formule générale

où Ri est un radical alkylène en C1-C6, de préférence en C1 -C2;
les acides amino-alcane-diphosphoniques de la formule générale

où F; = H, OH ou un radical alkyle en Cl-Cs, et n = 1 à 4, le nombre total d'atomes de carbone n'excédant pas 6, de préférence 2 ;;
les acides amino-bis-alkylene-phosphoniques de la formule générale

où R6 est un radical alkylène en C1 -C6, de préférence en C1 -C2;
les acides dialkylene-triamino-pentakis-alkylbne phosphoniques de la formule générale

où R7 est un radical alkylène en C1 -C6, de préférence en
C1-C2, et m - 1 à 6, de préférence 1 ou 2 ; et
les acides l-aminoalkylène-cyclopentyl-amino-2- tétrakis-alkylènephosphoniques de la formule générale

oU R8 et R9 sont chacun un radical alkyléne en C1-C6, de préférence en Cl-c2,
Comme exemples particuliers de ces types, on peut, citer l'acide amino-methane-diphosphonique, l'acide amino bis-methylene-phosphonique, l'acide diéthylêne-triamino- pentakis-methylene-phosphonique, l'acide ethylene-diamino- tétrakis-méthylène-phosphonique, l'acide l-aminométhylcyclopentylamino-2-tétrakis-méthyléne-phosphonique, et l'acide 1,2-cyclohexane-tétrakis-méthylène- phosphonique.Types of amino polyphosphonic acids which can be used in the invention are, for example, the alkylene-diamino-tetrakis-alkylene phosphonic acids of the general formula

or Rl and R2 are each a C1 -C6 alkylene radical, preferably Cl-Cz,
1. 2-cyclohexane-tBtrakis- alkylenephosphonic acids of the general formula

where R3 is a C-C6, preferably C1 t, alkylene radical
amino-trialkylenephosphonic acids of the general formula

where Ri is a C1-C6, preferably C1-C2 alkylene radical;
amino-alkane-diphosphonic acids of the general formula

where F; = H, OH or a C1-C5 alkyl radical, and n = 1 to 4, the total number of carbon atoms not exceeding 6, preferably 2 ;;
amino-bis-alkylene-phosphonic acids of the general formula

where R6 is a C1 -C6, preferably C1 -C2, alkylene radical;
dialkylene-triamino-pentakis-alkylbine phosphonic acids of the general formula

where R7 is a C1 -C6 alkylene radical, preferably in
C1-C2, and m - 1 to 6, preferably 1 or 2; and
1-aminoalkylene-cyclopentyl-amino-2-tetrakis-alkylenephosphonic acids of the general formula

where R8 and R9 are each a C1-C6, preferably C1-C2 alkylene radical,
As particular examples of these types, mention may be made of amino-methane-diphosphonic acid, amino bis-methylene-phosphonic acid, diethylene-triamino-pentakis-methylene-phosphonic acid, ethylene-diamino acid. tetrakis-methylene-phosphonic, l-aminomethylcyclopentylamino-2-tetrakis-methylene-phosphonic acid, and 1,2-cyclohexane-tetrakis-methylene-phosphonic acid.

The invention further relates to a stabilizing and activating composition suitable for carrying out the process of the invention and comprising, in% by weight based on the solid matter
- 1 to 15% of alkali metal silicate,
- 2 to 30% amino-polyphosphonic acid,
- 10 to 15% of soda or potash, and water for the complement to 100%.

 The amount of the composition according to the invention to be introduced into the bleaching bath may vary according to the bleaching process used, but this amount will usually be between 1 and 30 g per liter of bleaching bath.

 The invention also relates to a concentrated solution useful for the preparation of this composition, having excellent stability, consisting, by weight, of 3 to 89% approximately of an alkali metal silicate and of 11 to 97% of an acid amino-polyphosphonic.

 The bleaching bath is moreover of a completely conventional composition both with regard to its pH, its peroxide content, and the presence of any additives such as a wetting agent, being, of course, suitable for the process. of particular application used.

 The process of the invention lends itself well, moreover, to the simultaneous production of a dyeing of the cellulosic fiber using a direct dye or of a softening of said fiber using an agent. softening. I1 also authorizes the dyeing of the cellulosic fiber after the bleaching operation without having to change the bath or perform an intermediate rinsing.

The implementation of the present invention makes it possible to obtain numerous advantages and
- excellent stability of bleaching products and baths,
- an improvement in the degree of whiteness,
- good compatibility with direct and reactive dyes,
- good compatibility with softening compounds, and
- non-modification - of the touch of laundered articles.

 The following nonlimiting examples are given in order to illustrate the present invention.

EXAMPLE 1
A stabilizing and activating composition is produced by operating in the following manner
200 g of a sodium hydroxide solution containing 50% by weight of NaOH are introduced into 300 g of a sodium silicate solution containing 28% of SiO2 and kept stirring.

 Stirring is continued, 300 g of water at 20 ° C. are added, then 200 g of a 50% aqueous solution of ethylene-diamino-tetrakis-methylene-phosphonic acid are slowly introduced.

 The temperature rises to 50 C. A clear solution is obtained, retaining excellent stability after several months of storage at 25ex.

EXAMPLE 2
The procedure of Example 1 is repeated, except that the amino-polyphosphonic acid used in this example is replaced by an identical amount of diethyline-triaminopentakis-methylene-phosphonic acid.

 A clear solution is obtained having excellent stability after several months of storage at 25 ° C.

EXAMPLE 3
Oxidizing bleaching is carried out on an unbleached cotton fabric, previously boiled, using hydrogen peroxide under the following conditions
Samples of the tissue under consideration are impregnated in baths having the following composition
A - 15 cm3 / l Hydrogen peroxide at 35% by volume
10 cm / 1 Soda solution at 308 by weight
10 cm3 / l Stabilizing composition and
activator of example 1
2 g / l Wetting agent consisting of the product
condensation of nonylphenol with
10 units of ethylene oxide
B - 15 cm3 / l Hydrogen peroxide 35% by volume
10 cm3 / 1 Soda solution at 30% by weight
3 cm3 / 1 Sodium silicate used in
example 1
2 g / l Soda solution used in
example 1
0.5 g / l Magnesium chloride pentahydrate
2 g / l Wetting agent consisting of the product
nonylphenol condensation with 10
ethylene oxide units.

 A portion of baths A and B is maintained at a temperature of 80 ° C., then the amount of residual hydrogen peroxide in each bath is determined by iodometry, after 1 hour.

After 1 hour, it is observed that the amount of residual hydrogen peroxide is practically the same, this amount amounts to 65% in bath A, and 62% in bath
B. These results make it possible to demonstrate the stabilizing properties of the composition of the invention, although it is free of alkaline earth ions.

 The tissues are impregnated in the remaining part of baths A and B. After padding, then pressing to maintain a proportion of impregnation bath on the fabric, corresponding to 80% of the weight of the tissue, the samples are subjected to spraying for 20 minutes at a temperature of 103 ° C. The samples are then rinsed with cold water and dried.

 It is observed after treatment that the degree of whiteness of the sample obtained with bath A is significantly higher than that obtained with bath B.

The determination of the degree of whiteness, using an Elrepho apparatus from the company ZEISS, gave the following results
80% sample
Sample B 78%
EXAMPLE 4
Cold S bleaching is carried out on an unbleached cotton fabric under the following conditions
Fabric samples are impregnated in baths having the following composition
A - 40 cm3 Hydrogen peroxide at 35% by volume
40 cm3 Soda at 30% by weight
10 cm3 Stabilizing composition and
activator of example 2
6 g / l Wetting agent consisting of the product
condensation of nonylphenol with
10 units of ethylene oxide
B - 40 cm3 / 1 Hydrogen peroxide b 35% by volume
40 cm3 / 1 Soda at 30% by weight
3 g / l Sodium silicate used in
example I
2 g / l Soda solution used in
example 1
0.5 g / l Magnesium chloride pentahydrate
6 g / l Wetting agent consisting of the product
condensation of nonylphenol with
10 units of ethylene oxide
After impregnation and then expression carried out so as to maintain a proportion of impregnation bath corresponding to 100% of the weight of the fabric on the fabric, the samples are kept for 20 hours at 20 ° C. The samples are then washed with hot water , then cold water, and finally we dry them.

 After treatment, it is observed that the degree of whiteness of the sample obtained with bath A is significantly higher than that obtained with bath B.

EXAMPLE 5
The cotton fabric is bleached and dyed simultaneously using a direct dye. We operate as follows
Treatment bath,% by weight
2% Direct dye called Direct Black 71- (C.1.

N0 25040)
10% Sodium chloride
3% hydrogen peroxide at 35% by volume
2% Stabilizing and activating composition
example 1
1% aqueous sodium hydroxide solution at 30% by weight
Dyeing and bleaching are carried out for 1 hour 95ex. After treatment, the fabric is rinsed with cold water, then dried.

 After treatment, a normal color is observed with good removal of the impurities from the fiber.

 Comparatively, a treatment carried out in the presence of magnesium ions leads to a significant change in color with a lack of evenness in the dye.

EXAMPLE 6
Bleaching, then dyeing in the same bath, without intermediate rinsing, of a cotton fabric is carried out using reactive dyes. We adopt the following conditions
Bleaching is carried out by treating the fabric for 1 hour at 90 ° C. in a bath having the following composition
4 cm3 / 1 Hydrogen peroxide at 35% by volume
2 cm3 / l 30% aqueous sodium hydroxide solution
weight
2 cm3 / l Stabilizing composition and
activator of example 1
1 g / I Wetting agent
At the end of the treatment, 2 g / l of sodium thiosulfate are added to the bath in order to neutralize the hydrogen peroxide, the bath is cooled to 50 ° C., then introduced
2 g / l Reactive Red 12 Dye (CIN
18156)
100 g / l Sodium chloride
The dyeing is carried out in this bath for 30 minutes at 80 ° C., 10 g / l of trisodium phosphate are added in order to fix the dyes, then the dyeing is maintained for 45 minutes at 80 C.

 After treatment, a color corresponding to the usual intensity is obtained.

 An identical treatment carried out using a magnesium salt in the bleaching bath leads to precipitation in the dye bath when the trisodium phosphate is introduced.

EXAMPLE 7
A cotton fiber is bleached and softened simultaneously. We adopt the following conditions
Treatment bath
3 cm3 / 1 Hydrogen peroxide at 35% by volume
2 cm3 / 1 Stabilizing composition and
activator of example 1
1 cM / 1 35% aqueous sodium hydroxide solution
weight
4 cm3 / 1 20% by weight aqueous solution of
triethanolamine salt of an ester
phosphoric serving as a softener and
lubricant
The treatment is carried out for 1 hour at a temperature of 900C. After treatment, a good level of whiteness is obtained with an improvement in the touch.

 An identical test carried out in the presence of magnesium chloride causes the precipitation of the softening agent.

Claims (10)

 1. An improved process for bleaching cellulosic fibers carried out, under alkaline conditions, using a peroxide in the presence of an alkali metal silicate, characterized in that the bleaching bath also contains an amino acid -polyphosphonic and is devoid of alkaline earth ions.  2. A method according to claim 1, characterized in that the amino-polyphosphonic acid is chosen from the group formed by alkylene-diamino-tetrakis acids  alkylene phosphonics of the general formula

 where R1 and R2 are each a Cs-C6 alkylene radical,  1,2-cyclic acids oh ex ane-te t rakis- alkylenephosphonic of the general formula

 where R3 is a C1 -C6 alkylene radical,  amino-trialkylenephosphonic acids of the general formula

 where R4 is a C1C6 alkylene radical,  amino-alkane-diphosphonic acids of the general formula

 where R5 = H, OH or a C1-C5 alkyl radical, and n = 1 to 4, the total number of carbon atoms not exceeding 6,  amino-bis-alkylene-phosphonic acids of the general formula

 where R6 is a C1 -C6 alkylene radical, and  dialkylene-triamino-pentakis-alkylene phosphonic acids of the general formula

 where R7 is a C1 -C6 alkylene radical, and m = 1 to 6.  3. A method according to claim 2, characterized in that, in formulas I to III and V to VII, the radicals R1, R2, R3, R4, R6 and F; each represent a C1 or 2 alkylene radical and m = 1 or 2, and in that, in formula IV, the total number of carbon atoms does not exceed 2.  4. A method according to any one of claims 1 to 3, characterized in that, simultaneously with the bleaching operation, a dyeing of the cellulosic fiber is carried out using a direct dye.  5. A method according to any one of claims 1 to 3, characterized in that, after the bleaching operation, a dyeing of the cellulosic fiber is carried out using a reactive dye, without changing the bath, no intermediate rinsing.  6. A method according to any one of claims 1 to 3, characterized in that, simultaneously with the bleaching operation, a softening of the cellulosic fiber is carried out using a softening agent.  7. A stabilizing and activating composition suitable for carrying out the process of claim 1 and comprising, in% by weight based on the solid matter  - 1 to 15% of alkali metal silicate,  - 2 to 30% amino-polyphosphonic acid,  - 10 to 15% of soda or potash, and water for the complement to 100%.  8. A method according to any one of claims 1 to 3, characterized in that 1 to 30 g of the composition of claim 7 are introduced per liter of bleaching bath.  9. A method according to any one of claims 1 to 6 and 8, characterized in that the cellulosic fiber subjected to bleaching is a cotton fabric.  10. A concentrated stable solution useful for the preparation of the composition of claim 7, characterized in that it consists, by weight, of 3 to 89% approximately of an alkali metal silicate and of 11 to 97 approximately d 'an amino-polyphosphonic acid.