JPH0849164A - Method for bleaching synthetic fiber - Google Patents

Abstract

PURPOSE: To bleach synthetic fibers with a bleaching solution containing hydrogen peroxide under specific bleaching conditions in an excellent new bleaching effect. CONSTITUTION: This method for bleaching synthetic fibers such as polyester- based fibers, polyamide-based fibers, polyurethane-based fibers or acetate-based fibers comprises immersing the synthetic fibers in an acidic bleaching solution containing hydrogen peroxide (in a concentration of <=65 wt.%, preferably 20 to 35 wt.%) and an alkaline earth metal salt, preferably a magnesium salt and/or a calcium salt, in an amount of <=0.5 wt.% as a stabilizer for the bleaching bath for controlling the pH value of the solution to 3 to 7, preferably 5.0 to 7.0, at a bleaching temperature of 100 to 135 deg.C, preferably 120 to 130 deg.C, thereby bleaching the synthetic fibers in an excellent white degree. The bleaching solution may further contain 0.1 to 5 g/L of an organic complexing agent, 0.1 to 5 g/L of a bleaching auxiliary (for example, a protein decomposition product), 0.5 to 3 g/L of a surfactant (for example, an alkyl sulfate salt), 0.5 to 10 g/L of a polyphosphate salt, and 0.1 to 5 g/L of a fluorescent brightening agent.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for bleaching synthetic fibers.

[0002]

BACKGROUND OF THE INVENTION Many everyday product manufacturing processes often include a process known as bleaching. Bleaching has the function of changing the color of the material to a light shade. The ultimate goal is to be pure white. There should be no, if any, change in the material itself due to this treatment. This bleaching plays an important role for textile fibers. Textile fibers are further divided into natural fibers and artificial fibers. The former is of animal origin (wool,
Silk) and vegetable (cotton, flax). Artificial fibers include synthetic fibers, including polyamide fibers, polyester fibers, polyacrylonitrile fibers, polyurethane fibers. In the textile industry, it is common to bleach textile fibers with oxidizing agents. Known chemicals for this purpose include hydrogen peroxide, sodium chlorite, peracids. Hydrogen peroxide is mainly used for the above-mentioned natural fiber and mixed fiber.

German Patent Publication A 224906
No. 2, bleaching textile fibers containing cellulose, such as cotton / polyester, with a bleaching agent consisting of an aqueous hydrogen peroxide solution, an alkali metal hydroxide, an alkali metal borate and an organic complexing agent. Was disclosed. The bleach is 0.2% of 100% hydrogen peroxide to the textile fiber.
It is preferable that the content is ˜1.8 wt% and the pH is 9.5 to 11.5. The bleaching agent is preferably used by impregnating the textile fiber with a proportion of 50 to 125% by weight based on the textile fiber.

Federal Republic of Germany Patent Publication A002292
No. 9 refers to a method of bleaching synthetic fibers, in particular polyester-cotton fabrics, such as for example an emulsion of an aqueous hydrogen peroxide solution dissolved in a hydrocarbon or hydrocarbon halide solvent. A bleach emulsion or suspension is applied to the textile fibers to thoroughly remove the solvent from the textile fibers and then to wash the textile fibers.

United States Patent Publication A3649164
No. 6,058,049 shows a process for bleaching textile fibers containing cellulose, for example polyester-cotton textile fibers, which generally comprises 0.5 to 1.5 hydrogen peroxide based on the weight of the fibrous material.
%, Water-soluble peroxydiphosphate 0.05-0.5
%, And an alkaline aqueous hydrogen peroxide solution having a pH of 9 to 14 is used. 140 to bleach textile material
Pretreatment with the bleaching solution at ~ 160 ° F, then heating to the boiling point of the bleaching solution while soaking in the bleaching solution.

All of the above bleaching methods relate to bleaching polyester blend fabrics. Federal Republic of Germany Patent Publication A3
No. 002726 discloses a method for bleaching fiber materials with hydrogen peroxide, which bleaches the fiber material with hydrogen peroxide in a weakly acidic medium under conditions of pH 5-7.
The bleaching system is then mixed with an alkaline bleach and the pH is adjusted to 8.
Set to 5-11 and consist of continuing bleaching with hydrogen peroxide in a weakly basic medium.

Fiber materials to be bleached include, for example, natural, synthetic and cellulosic fibers. The use of this bleaching method for cotton, wool-cotton blends, polyester-cotton blends is demonstrated in the examples. It is noted in the references that bleaching with hydrogen peroxide in a weak acid with a pH range of 5 to 7 described above yielded whiteness achieved by bleaching with sodium chlorite alone. ing. Comparing conventional multi-step bleaching methods involving the steps of dechlorination or antichlorination of sodium chlorite and additional bleaching with hydrogen peroxide in weakly basic medium, a comparison of conventional multi-step bleaching The bleaching method, which uses only hydrogen peroxide, is said to be impractical.

[0008]

The use of hydrogen peroxide as a bleaching agent on synthetic fibers has been investigated as beneficial in several respects, but has not achieved a sufficient bleaching effect. (Ulmann's Encyklopaedie der technisc
hen Chemie, 4th edition, volume 23, page 25, 1984
Other bleaching agents were considered to have an insufficient bleaching effect, so sodium chlorite was considered as the only bleaching agent suitable for polyesters. (BASF-Handbuch, volume
363d, 8/74, page 81; K. Lindner, Tenside-Textilhil
(See fsmittel-Waschrohstoffe III, page 2749, 1971)

[0009]

Surprisingly, it was discovered that by using a bleaching solution consisting of an aqueous solution of hydrogen peroxide here, even synthetic fibers such as polyester fibers can be sufficiently bleached. Even more surprising is that
It was found that the bleaching effect was improved by using the above bleaching solution containing polyphosphate.

The present invention relates to a method of bleaching synthetic fibers with hydrogen peroxide, which method has a pH of the bleaching solution of 3 to.
7. Bleaching synthetic fibers with a hydrogen peroxide bleaching solution at a temperature of 100-135 ° C.

Examples of synthetic fibers are polyester fibers, polyamide fibers, polyurethane fibers, acetate fibers. A polyester fiber is used for reference. According to the method of the present invention, not only conventional polyester fibers but also flame-retardant polyester fibers (Chemie fuer Textilindustrie, 43
-95, page 65-68, 1993) and excellent bleaching properties have been demonstrated for special polyester fibers such as polyester microfibers.

The bleaching solution is usually used in the form of an aqueous hydrogen peroxide solution. Theoretically, the hydrogen peroxide solution for making the bleaching solution can be used in any concentration, but in the best case a hydrogen peroxide solution with a concentration of up to 65% by weight is preferred. Generally, 20 to 35% by weight is preferable. For example, the concentration of 35% hydrogen peroxide water is preferably 1.0 to 20 ml / L with respect to the bleaching solution. It is possible to use a large amount of hydrogen peroxide, but no great effect is obtained.

In order to obtain an improved bleaching effect, it is advantageous for the bleaching solution to contain a certain amount of polyphosphate. These polyphosphates have the general formula Me _{n + 2} P _n O
_{3n + 1} or Me _n P _n O _3n (wherein, Me represents an alkali metal ion, alkaline earth metal ions, ammonium ion, n represents represents 1-6) is preferably a compound represented by. Here, Me is preferably an alkali metal ion, and particularly preferably a sodium ion. Examples of such polyphosphates are compounds represented by the general formula Na ₆ P ₆ O ₁₈ or Na ₆ P ₆ O ₁₀ . Particularly excellent bleaching effect is ensured by using these polyphosphates. Normally,
The bleaching solution contains 0.5 to 10 g / L, especially 2-3 g / L of polyphosphate.

In the usual case, the bleaching solution according to the invention will additionally contain other suitable components. These include stabilizers that prevent the decomposition of hydrogen peroxide and negate the presence of catalysts that cause this decomposition. Customary stabilizers are alkaline earth metal salts. Among these alkaline earth metal salts, magnesium silicate is particularly important. Water soluble magnesium and calcium salts such as magnesium sulfate, calcium chloride are also suitable. The bleaching solution preferably contains up to 0.5% by weight, in particular up to 0.3% by weight of alkaline earth metal salts.

The bleaching solution of the present invention may contain an organic complexing agent such as aminocarboxylic acid or its alkali metal salt or ammonium salt. This aminocarboxylic acid contains one or more amino groups, and it is preferred that at least one amino group is substituted by two carboxylic acid groups, in particular acetic acid groups or substituted acetic acid groups. Examples of preferred complexing agents are ethylenediaminetetraacetic acid, N- (2-hydroxyethyl) ethylenediaminetriacetic acid, diethylenetriaminepentaacetic acid, triethylenetetraaminehexaacetic acid or one or more acetic acid groups having (2-hydroxyphenyl) acetic acid. Is one of the above compounds substituted with. A more preferred complexing agent is diethylenetriaminepentaacetic acid or its alkali metal salt. Further suitable complexing agents are, for example, carboxylic acids such as gluconic acid and phosphonic acids or their alkali metal salts or their ammonium salts, these being Chwala-Anger, Handbuch der Textilhilfs
mittel, pp.1003-1008, 1972.

The content of complexing agent in the bleaching solution is usually 0.1 to 0.1%.
It is 5 g / L, preferably 0.2 to 1 g / L.
The amount of complexing agent is determined by the concentration of hydrogen peroxide-decomposing metal or the purity of the water and the quality of the synthetic fiber.

The bleaching solution of the present invention further comprises a bleaching aid such as a proteolytic product or an organic phosphate ester, especially an alkyl or alkylaryl phosphate ester.
It may contain 1 g / L. Specific examples of phosphoric acid esters are alkyl and alkylaryl esters of poly (ethyleneoxy) phosphoric acid.

The bleaching solution according to the invention may additionally contain a surfactant, preferably a foam-free wetting agent which facilitates the washing of the synthetic fibers following bleaching. Anionic or nonionic surfactants can be used. Examples of suitable compounds are condensates of alkylphenols such as nonylphenol with ethylene oxide, for example alkylaryl sulphonates such as the amine salt of dodecylbenzene sulphonic acid and straight-chain alkyl sulphates. The concentration of the surfactant is usually 0.5 to 3 g / L, preferably 1 to 2 g / L.

The bleaching solution may also contain an optical brightener. The amount used is usually 0.1 to the bleaching solution.
It is 5 g / L. This ensures the optimum effect of the bleaching and bleaching process in one step. It also eliminates the need for chlorite-stable optical brighteners when compared to current bleaching methods involving sodium chlorite.

It is likewise possible to use small amounts of alkali metal carbonates, for example sodium carbonate. The bleaching solution is weakly acidic to neutral, and particularly has a pH of 3.0 to 7.
0, especially pH 5.0 to 7.0 is preferred. In order to obtain the optimum bleaching effect, the pH is determined, for example, by the nature and quality of the fiber material and can be set and adjusted, for example by changing the concentration of acid or adding acetic acid.

Generally, the bath ratio is 3: 1 to 40: 1, especially 1
Bleach synthetic fibers at 0: 1 to 20: 1. Temperature is 100
Bleach synthetic fibers at elevated temperatures of ~ 135 ° C, especially 120-130 ° C. At this temperature, the required steam pressure is preferably 1 to 3.5 atm, especially 2 to 3 atm.
The time required to obtain a certain bleaching effect at a certain temperature is determined by that temperature. 80 to 120 minutes is preferable at 100 ° C, and 10 to 30 minutes is preferable at 135 ° C. Considering all temperature ranges, processing time is 1
It is 0 to 120 minutes.

Following the bleaching treatment, it is preferred to wash the bleached textile material with warm, neutral water. The method of the present invention is carried out in conventional high temperature bleaching equipment.

The method of the present invention makes it possible to obtain a whiteness equivalent to that obtained by the conventional method using, for example, chlorous acid. Furthermore, the method of the present invention is carried out in one step, requiring only one bleaching device. Avoiding the use of conventional bleaching agents such as sodium chlorite brings a great deal of environmental benefit. Compared to conventional bleaching methods involving sodium chlorite, this method does not require a chlorite-stable brightener. In addition, the equipment of the device used is
There is no exposure to the corrosive conditions that occur during this process.

[0024]

EXAMPLES The obtained whiteness was determined by the Ganz method (R. Griesser, Re
v. Prog. Coloration, Vol. 11, p. 25, 1981)). Example 1 Using a bleaching solution containing 5 ml / L of a 35 wt% hydrogen peroxide aqueous solution, a pH of 6 to 7 and a temperature of 45 minutes or more 130
The polyester fabric is bleached under conditions kept at ° C. The bath ratio is 20: 1. A whiteness of 80 is obtained. Example 2 Using a bleaching solution containing 5 ml / L of 35 wt% hydrogen peroxide aqueous solution and 3 g / L of sodium polyphosphate, p
H is 6 to 7 (adjusted with acetic acid), temperature is 130 for 45 minutes or more
The polyester fabric is bleached under conditions kept at ° C. The bath ratio is 20: 1. A whiteness of 85 is obtained. Example 3 5 ml / L of 35 wt% hydrogen peroxide aqueous solution, 3 g / L of sodium polyphosphate and optical brightener (Hosta
The woven fabric of polyester is bleached using a bleaching solution containing 0.5 g / L of lux ERE) at a pH of 6 to 7 (adjusted with acetic acid) and at a temperature of 130 ° C. for 45 minutes or longer. The bath ratio is 20: 1. A whiteness of 215 is obtained. Comparison with Example 1 (German patent publication A 300 2726) 35
A bleaching solution containing a 5% by weight aqueous solution of hydrogen peroxide at a pH of 6.9 is adjusted in a weak acid medium, and a polyester fabric is bleached under conditions of 90 ° C. for 60 minutes or longer. Thereafter, the bleaching system is mixed with an alkaline substance (sodium hydroxide aqueous solution containing sodium silicate), the pH is adjusted to 11 in a weak alkaline medium, and the fabric is bleached under the condition of keeping at 80 ° C. for 60 minutes or more. The bath ratio is 10: 1. A whiteness of 81 is obtained. Comparison with Example 2 (Sodium chlorite bleaching) 1.
5 g / L, bleaching aid 1.0 g / L and wetting agent (Ho
4 g of bleaching solution containing 0.5 g / L of
The polyester fabric is bleached under conditions of 130 ° C. for 5 minutes or more. The bath ratio is 20: 1. A whiteness of 86 is obtained.

Claims (20)

[Claims] 1. A method of bleaching a synthetic fiber using hydrogen peroxide, which comprises using a bleaching solution containing hydrogen peroxide, wherein the pH of the solution is 3 to 7, and the temperature is 100 to 135 ° C. The above method of bleaching synthetic fibers under conditions. 2. The method according to claim 1, wherein the synthetic fibers used are polyester fibers, polyamide fibers, polyurethane fibers or acetate fibers. 3. The method according to claim 1, wherein the bleaching solution comprises an aqueous hydrogen peroxide solution having a concentration of up to 65% by weight. 4. The method according to claim 1, wherein the bleaching solution contains an aqueous hydrogen peroxide solution having a concentration of 20 to 35% by weight. 5. The method according to claim 1, wherein the solution further comprises a stabilizer. 6. The method according to claim 5, wherein the stabilizer used is an alkaline earth metal salt, preferably a magnesium salt and / or a calcium salt. 7. The method according to claim 5, wherein the bleaching solution contains 0.5% by weight or less, preferably 0.3% by weight or less, of an alkaline earth metal salt. 8. The method according to claim 1, wherein the solution is an organic complexing agent, preferably an aminocarboxylic acid or an alkali metal salt thereof. 9. The process according to claim 8, wherein the bleaching solution contains 0.1 to 5 g / L, preferably 0.2 to 1 g / L of organic complexing agent. 10. A bleaching solution comprising 0.1 to 5 g / L, preferably 0.2 to 1 g / L of bleaching aid.
The method described in any one of. 11. The process according to claim 10, wherein the bleaching aid used comprises proteolytic products, alkyl phosphates and / or alkylaryl phosphates. 12. The bleaching solution comprises a surfactant.
The method according to any one of 1 to 11. 13. The process according to claim 12, wherein the surfactant used comprises condensates of alkylphenols, alkylaryl sulphonates and / or alkyl sulphates. 14. The method according to claim 12, wherein the bleaching solution contains 0.5 to 3 g / L, preferably 1 to 2 g / L of a surfactant. 15. The method according to claim 1, wherein the bleaching solution contains 0.5 to 10 g / L, preferably 2-3 g / L of polyphosphate. 16. The polyphosphate used has the general formula Me
_{n + 2}P_nO_{3n + 1}Or Me _nP_nO_3n(In the formula, Me is an alkali
Metal ion, alkaline earth metal ion, ammonium ion
It represents ON, and n represents 1 to 6).
How to list. 17. The method according to claim 1, wherein the bleaching solution contains 0.1 to 5 g / L of an optical brightener. 18. The method according to claim 1, wherein the bleaching solution has a pH of 5.0 to 7.0. 19. The method according to claim 1, wherein the bleaching solution is used at 120 to 130 ° C. 20. The method according to claim 1, wherein the bath ratio is 3: 1 to 40: 1, preferably 10: 1 to 20: 1.