JPS6115182B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method of bleaching cellulose fibers using a novel bleaching aid in hydrogen peroxide steam bleaching. Conventional hydrogen peroxide steam bleaching of cellulose fibers involves padding a cloth with a solution containing hydrogen peroxide, sodium silicate, an alkaline agent, and a penetrating agent.
It was steam-treated at high temperatures around ℃. The pH of this pad solution is over 10, and although sodium silicate is added as a stabilizer, hydrogen peroxide gradually decomposes in the saturator, so the concentration of hydrogen peroxide cannot be maintained at a constant concentration for a long period of time or more. In reality, it is impossible to maintain the pad fluid, and the pad fluid must be replaced every day. Furthermore, the addition of sodium silicate is not at all desirable because it causes so-called silicate disorder. Furthermore, high alkali and high temperature treatments have the disadvantage of making the fibers loose and stiff, resulting in poor texture. The object of the present invention is to provide a bleaching method which overcomes the above-mentioned disadvantages. The bleaching method of the present invention uses a near-neutral method that does not contain any sodium silicate or alkaline agents.
It is characterized by applying a PH padding liquid to the fibers, treating it with ammonia gas and steaming it at 70 to 100°C. According to the bleaching method of the present invention, the pad solution is kept neutral, so the H ₂ O ₂ in the saturator is kept very stable. In addition, sufficient whiteness can be obtained even at a bleaching temperature of about 70°C, reducing energy costs, and in addition, products with good texture and no silicate damage can be obtained. Several studies have been conducted on neutral bleaching using H ₂ O ₂ . For example, Patent Publication No. 30234/1986 proposes a method using one or more substances selected from urea, dianates, sulfamic acids, and sulfamic acid salts, and condensed phosphates. Also, Patent Publication 1977-
30235 proposes a method of using a substance selected from the group consisting of phosphoric esters and phosphoric esters in combination with a substance selected from the group consisting of urea, amides, imides, dianates, sulfamic acids, and sulfamic acids. ing. However, these methods are insufficient for the activation of H ₂ O ₂ ;
Although it is somewhat effective for thin fabrics, when applied to bleach thick fabrics, the degree of bleaching is low and the removal of neps is incomplete. Acidic bleaching using hydrogen peroxide is also proposed in Patent Publication 1983-34674. This is a method in which an oxycarboxylic acid such as lactic acid, tartaric acid, citric acid, or glycolic acid is used in combination with hydrogen peroxide to generate an organic peracid, which is then bleached with acid. However, according to this method, removal of neps from cotton fabric is very difficult, and it would be impossible to apply it to actual bleaching. Additionally, some methods have been proposed in which so-called non-silicate stabilizers that do not contain sodium silicate are used. For example, Patent Publication No. 10425, proposed by the applicant, describes a method using a fatty acid alkali metal salt and a readily soluble magnesium salt, and Patent Publication No. 34675, which has been proposed by the applicant, discloses a method using a water-soluble protein. Methods etc. are described.
However, although the former of these methods is effective for patch bleaching, the steaming bleaching method has an insufficient bleaching effect compared to the bleaching method using sodium silicate. Furthermore, the latter poses a problem in terms of cost. However, the bleaching method of the present invention, in which a solution containing hydrogen peroxide and citrate is padded onto cloth and then steamed with ammonia gas, has a remarkable bleaching effect even at temperatures of about 70°C, and is effective even on thick cloth. It is fully applicable. Also, since it is a non-silicate bleaching method that does not contain any silicate, it has great advantages. As the easily soluble citrate, sodium salt, ammonium salt, potassium salt, etc. can be used, and the amount of citrate used is 0.05 to 1.0 based on the amount of solution.
%, preferably 0.1 to 0.3%. Adding less than 0.05% has no effect, and adding more than 0.1% does not change the effect, making it uneconomical. In this case, the addition of urea and synthetic phosphates brings good results, but the addition of oxycarboxylate salts other than citrate, such as tartrate, glycolate, malate, lactate, and glycerate, has no effect. The bleaching method of the present invention is also characterized by the use of ammonia gas before or during steaming. In this case, ammonia gas may be directly introduced into the steamer from a cylinder, or aqueous ammonia may be held at the bottom of the steamer and supplied into the steamer by evaporation. Another common alkaline agent. Caustic soda, soda carbonate, calcium hydroxide, calcium carbonate, etc. cannot be used because they are difficult to gasify. The appropriate amount of ammonia gas to be supplied is 0.1% to 20% by weight based on the weight of the fibers. If the amount of ammonia gas used is less than 0.1%, no brightening effect will be obtained, and if the amount of ammonia gas used is more than 20%, the fibrous material will become extremely brittle, which is not desirable. The ammonia gas treatment may be performed by padding the fibers with a bleaching solution, supplying ammonia gas for a certain period of time, and then steaming the fibers, or by simultaneously applying steaming to the fibers. Ammonia must be in a gaseous state during processing; for example, if aqueous ammonia is added to the padding solution, the padding solution will naturally become alkaline and H ₂ O ₂ will become unstable, as well as the steaming process of the padded fibers. Even if you do this, the bleaching effect is small. Next, Examples and Comparative Examples will be given to explain the present invention more specifically, but these are not intended to limit the present invention in particular. Example 1 A 40 count cotton knitted fabric scoured with an aqueous solution containing 40g/35% (weight) hydrogen peroxide solution, 2g/ sodium citrate (dihydrate), 1g/ sodium hexametaphosphate, and 2g/nonionic surfactant. Sufficiently permeate the gas, squeeze it to an objective weight of 100℃, put it in a steamer, and add ammonia gas to an objective weight of 0.1%/mim.
was fed for 5 minutes at room temperature. Next, steam is introduced and heated at 70℃ for 30 minutes, then washed with hot water and water.
The whiteness of the bleached cloth was measured using a Hunter whiteness meter. In addition, using Tensilon (manufactured by Toyo Baldwin), the resistance value when a cotton knitted cloth cut into a square of 10 cm x 10 cm passes through a metal ring with an inner diameter of 3 cm was taken as the texture value. The whiteness and texture of the cloth before bleaching were also measured. Table 1 shows the results.
Shown below. (Scouring conditions are NaOH30g/, squeezing rate
100%, 100℃ x 30 minutes)

[Table] Example 2 An aqueous solution containing 40 g of 35% (by weight) H ₂ O ₂ solution, 4 g of ammonium citrate, 5 g of urea, and 2 g of nonionic surfactant was sufficiently penetrated into a 40-count refined cotton knitted cloth. The ammonia gas is reduced to 100% of the objective weight in a steamer.
Steaming was performed at 100° C. for 30 minutes while supplying 0.07%/mim. Thereafter, the fabric was washed in hot water, washed in water, and dried in this order, and its whiteness and texture were measured in the same manner as in Example 1. The results are shown in Table 2.

[Table] Comparative Example 1 A 40-count cotton knitted cloth scoured in the same manner as in Example 1 was mixed with 35% (by weight) H ₂ O ₂ aqueous solution 40 g/, sodium hexametaphosphate 1 g/, nonionic surfactant 2 g/, and various oxidants. Put it in an aqueous solution containing 2 g of acid soda, let it penetrate thoroughly, and then add it to an objective weight of 100
%, placed in a steamer, and ammonia gas was supplied at a rate of 0.1% objective weight/mim for 5 minutes at room temperature. Next, steam was introduced and the fabric was heated at 70°C for 30 minutes, followed by washing in hot water, washing in water, and drying in that order.The whiteness of the bleached fabric was measured using a Hunter whiteness meter. Table 3 shows the whiteness of each sodium oxyacid. The whiteness of the cloth before bleaching is 69.5.

[Table] Comparative Example 2 A 40-count cotton knitted fabric scoured under the same conditions as Example 1 was placed in a bleaching solution with the following composition, thoroughly penetrated, squeezed to 100% objective weight, placed in a steamer, and heated to 70% by weight. After steaming at ℃ for 30 minutes, wash with hot water, wash with water,
The whiteness of the bleached cloth was measured using a Hunter whiteness meter. The whiteness before bleaching was 69.5, and the whiteness after bleaching was 87.6.

[Table] Comparative example 3 H ₂ O ₂ (35%) 40ml, sodium citrate 2g/,
To an aqueous solution containing 1 g of sodium hexametaphosphate and 2 g of a nonionic surfactant, aqueous ammonia (28%) was added in amounts (a) to (d), respectively, to prepare a bleaching solution. (a) 0.5g/ (b) 1.0g/ (c) 5.0g/ (d) 20.0g/ Add 40 count cotton knitted cloth scoured in the same manner as in Example 1 to each of these bleaching solutions and pour the solution. After sufficiently permeating, squeeze this to 100% of the objective weight, put it in a steamer, and steam it at 70℃ for 30 minutes.
The bleached cloth was washed in hot water, washed with water, and dried in this order, and the whiteness of the bleached cloth was measured using a Hunter whiteness meter. The results are shown in Table 4.

【table】

Claims (1)

[Claims] 1. In bleaching cellulose fiber products, the fibers are padded with an aqueous solution containing hydrogen peroxide and easily soluble citrate, treated with ammonia gas and
A method of bleaching textile products using steam treatment with steam at ℃.