JPS5943584B2 - Cold bleaching of textiles - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for bleaching fibers, and more specifically to a method for simultaneously desizing, scouring, and bleaching cotton and blended, blended, and knitted fiber products of cotton and other fibers at low temperatures. It concerns a method of cold bleaching textiles.

Bleaching of fibers has been progressing from a dipping method to a continuous method in order to save labor.

However, the continuous bleaching method requires expensive bleaching equipment and requires a large capital investment. Small and medium-sized bleaching companies are often unable to adopt continuous bleaching due to lack of capital.
Continuous bleaching usually requires a heating process of 100°C or higher, and when oil was cheap, heating above 100°C did not have a large effect on bleaching costs, but the recent rise in oil prices has increased the temperature to 100°C or higher. The energy cost of the heating process has come to weigh heavily on the bleaching process cost. For these reasons, the bleaching industry has developed a bleaching method that is similar to continuous bleaching, does not require expensive equipment, does not require much energy, and can produce products of the same high quality as conventional continuous bleaching. We are eagerly awaiting an effective cold bleaching method.

To express the principle of the cold bleaching method simply, it is called continuous bleaching without using a heating process, that is, a steamer box. The basic elements of normal continuous bleaching consist of three steps: (bleach padding) → (steaming) → (washing), and these are processed continuously at high speed, but in the cold bleaching method, bleach solution padding This process involves continuous washing and steaming, and the steaming (heating process) has been replaced with long-term storage at low temperatures. In addition, since the long-term storage at low temperatures makes it possible to utilize the idle time at night, the amount of bleaching to be processed can be maintained at the same level as in the conventional continuous bleaching method. It has been known for many years that fibers can be bleached with a hydrogen peroxide solution at low temperatures, and the cold bleaching method of one-bath desizing, scouring, and bleaching and one-bath scouring and bleaching is known as 36-2
3834 is known, but these known techniques have various drawbacks and cannot produce high-quality textile products comparable to ordinary continuous bleaching, and there are few examples of industrialization.

Therefore, the present inventors conducted intensive research to see if it was possible to obtain high-quality textile products by simultaneously processing desizing, scouring, and bleaching in a cold bleaching method, and as a result, they arrived at the present invention. That is, the method of the present invention applies to PHll. 5-12.5, Mg++ 20-200pp
m, passing the fiber through a peroxide bleaching solution containing peroxide in an amount of 20 to 70 CC/l at 35% H2O2,
A fiber bath characterized by absorbing a peroxide bleaching solution so that the squeezing rate becomes 75 to 175% of the fiber weight, and leaving the resulting wet fibers at a temperature of room temperature to 50°C for 5 hours or more. This is the desizing, scouring, and bleaching method. The peroxide bleaching solution of the present invention can effectively perform desizing, scouring, and bleaching at the same time.
l. 5 to 12.5, preferably PHll. 8-12.2
is adjusted to

As the alkaline agent for pH adjustment, caustic soda, alkali metal hydroxide of caustic potash, etc. are used. PHll. If it is less than 5, the bleaching blade of hydrogen peroxide is insufficient, resulting in crushed cotton residue and insufficient whiteness. In addition, the scouring effect and desizing effect are reduced, water absorption is reduced, and size remains. At PHL 2.5 or higher, hydrogen peroxide decomposes rapidly, resulting in crushed cotton residue, insufficient whiteness, uneven bleaching, and strength deterioration. The amount of hydrogen peroxide used in the present invention is 3
Add H20 to 70 CC/l with 5% H2O2 or with hydrogen peroxide adducts such as sodium perborate or sodium percarbonate.
20 to 70 CC/f with 35% H2O2 liberating 2O2!
Use the amount that is. If it is less than 20 CC/l, it tends to cause flocculation residue and lack of whiteness, and if it is more than 70 cC/f, it is meaningless in terms of effectiveness and may cause strength deterioration in some cases.

In the present invention, it is preferable to use an anionic or nonionic surfactant that is commonly used in textile bleaching in order to improve the penetration of chemicals into fibers and to provide an auxiliary effect for scouring.

The amount to be used is determined according to the application amount of each commercially available product, and in general, the appropriate amount is 0.1 to 2 y/l in terms of pure content. Also H2
Silicic acid such as sodium silicate or potassium silicate is usually used as No. 3 silica in an amount of 1 to 507 y/l, preferably 7.5 to 15 y/l, for the purpose of stabilizing O2, scouring auxiliary effect, and complete removal of cotton debris. Preference is given to using salt.

If it is less than 17/l, there will be a tendency to leave crushed cotton residue and lack of whiteness, and if it is more than 507/l, it will be meaningless in terms of effectiveness, and excessive use of silicate will cause silicic acid scale problems.

In addition, phosphates,
It is preferable to use a phosphate hydrogen peroxide adduct and a persulfate or two or more thereof.

Phosphate and lysate salt hydrogen peroxide adducts include sodium orthophosphate, sodium pyrophosphate, sodium tripolyphosphate, etc., and their hydrogen peroxide adducts, and persulfates include potassium persulfate and sodium persulfate. , ammonium persulfate, etc. The amount used varies depending on the type of fiber, but usually 0.5 to 10 y/11 each, preferably 2 to 10 y/11 each.
5y/l, and each may be used alone or in combination. In the present invention, it is essential to add Mg++ to stabilize hydrogen peroxide, and Mg++ is 20 to 200 ppm1, preferably 30 to 80 ppm.
One-bath desizing, scouring, bleaching and one-bath scouring in the presence of ppm
Bleaching is carried out.

Normally, in hydrogen peroxide bleaching for the sole purpose of bleaching, it is known that 2 to 8 ppm of Mg++ contained in the water provides a sufficient hydrogen peroxide stabilizing effect, but in the case of the method of the present invention, the water The purpose of the present invention cannot be achieved because the hydrogen peroxide stabilizing effect is insufficient if only 10 amounts of Mg are used. However, when an appropriate amount of Mg++ is present, hydrogen peroxide is significantly stabilized, and the object of the present invention is achieved.

Since Mg++ is contained in normal water at a concentration of 2 to 8 ppm, the insufficient amount is newly added to the bleaching solution, and the above-mentioned preferred Mg
Adjust so that it becomes ++. In this case, Mg++ is preferably added to the bleaching solution in the form of Epsom salt. Next, in the method of the present invention, the fibers are passed through the peroxide bleaching solution described above, the fibers are allowed to absorb the peroxide bleaching solution, and the one-bath desizing, scouring, and bleaching is completed through a standing step and a washing step. .

At that time, the amount of peroxide bleaching solution absorbed by the fibers varies depending on the type of fiber, but preferably the squeezing rate is 7% relative to the weight of the fibers.
Adjust to 5-175%. If the squeezing ratio is less than 75%, crushed cotton remains and whiteness is insufficient, and the object of the present invention cannot be achieved. Moreover, 175% or more is meaningless in terms of effectiveness. The fibers thus wetted with the peroxide bleaching solution are left for 5 hours or more under a temperature condition of room temperature to 50° C. without much water evaporation. To leave the peroxide bleaching solution at an appropriate temperature between room temperature and 50°C, the peroxide bleaching solution is allowed to pass through the fibers, and the wet fibers are shaken off on a trolley or rolled up. The entire container is sealed with a sheet of polyethylene, PVC, etc. to prevent moisture from evaporating as much as possible and the temperature from dropping. Alternatively, store those sealed wet fibers at room temperature
Leave it in a room maintained at an appropriate temperature of 0°C. The higher the temperature of the peroxide bleaching solution and the temperature at which it is allowed to stand, the better the effect will be, but if the temperature exceeds 50°C, the decomposition of H2O2 will become more intense, resulting in insufficient bleaching, leftover cotton residue, and deterioration in strength, which is undesirable.

The leaving time is preferably 5 to 20 hours, more preferably 1
If the reaction time is 0 to 15 hours or less than 5 hours, the purpose of the present invention cannot be achieved due to insufficient reaction, and if the reaction time is more than 20 hours, the effect has already reached its peak, and if the reaction time is left for more than 20 hours, there is no adverse effect on the fibers, but this is not reasonable.

The method of the present invention consists of impregnating and absorbing a peroxide bleaching solution on the fibers and then leaving them under suitable temperature conditions. However, before passing the fibers through the peroxide bleaching solution, the following pretreatments are carried out, for example: It is even more effective if you do this. As a pretreatment, the fibers are boiled in hot water at 80 to 100°C for 1 to 60 seconds, then passed through water for cooling purposes, and the water content of the fibers is reduced as much as possible using a squeezing mangle, followed by peroxide bleaching. Move on to the liquid impregnation process.

The method of the present invention is completed by continuously washing the fibers after the standing operation is completed, and removing chemicals and impurities remaining in the fibers, as is done in normal continuous bleaching. However, initial cleaning is required to remove chemicals and impurities.
It is preferable to use hot water of 0 to 100'C and gradually lower the temperature.

The fibers applicable to the present invention are cotton, blends, blends, knits, and other textile products of cotton and other fibers. Of course, the following textile products that cannot be subjected to continuous bleaching at high temperatures can also be effectively bleached.

For example, raised products (such as flannel fabric), knitted fabrics, etc. that require high hand feel become extremely hard when subjected to continuous alkaline H2O2 bleaching at high temperatures, and could not be made into products, but the method of the present invention can It has a noticeably soft texture and can be continuously bleached for brushed and knitted items. Furthermore, when acrylic/cotton is subjected to continuous alkaline H2O2 bleaching at high temperatures, yellowing of the acrylic occurs and high whiteness cannot be obtained; however, when bleaching is performed using the method of the present invention, there is no yellowing of the acrylic, and acrylic/cotton is Can be bleached continuously.

As described above, the method of the present invention does not require the heating process that is carried out in ordinary continuous bleaching, and enables a method that simultaneously performs desizing, scouring, and bleaching using a cold bleaching method, resulting in high-quality products. can be produced continuously.

The method of the present invention makes it possible to utilize the idle time at night, and also enables the continuous bleaching of textile products that cannot be bleached by conventional high-temperature alkaline hydrogen peroxide continuous bleaching. This significantly improved the quality of bleached products.

A more detailed explanation will be given below using Examples and Comparative Examples.

The whiteness, strength, water absorption, size residue, and cotton residue are measured based on the following methods. (1) La-b using Hakudo Nippon Denshoku Kogyo Co., Ltd. color studio
Measure using the system.

L. a. b indicates the following meanings L: Lightness a: (A) Reddish (C) Greeny B. (a) Yellowish (c) Bluish Among these, the b value was used for judgment because it corresponds well with visual perception.

The smaller the b value, the lower the yellowing, that is, the higher the whiteness. Commercially, a b value of 2.0 to 3.0 is usually required. (2) Strength The tensile strength was measured using a Schottper type tensile strength tester, and the untreated fiber was set as 100%, and the strength retention rate was determined.

(3) Water Absorption A 1-inch square sample was prepared, the sample was floated parallel to the water surface, and the time required for the sample to settle from above the water surface to below the water surface was measured and determined.

The shorter the settling time below the water surface, the better the water absorbency, and if the settling time is 30 seconds or less, it is usually satisfactory commercially. (4) Thickness remaining The 1/10 NI-KI solution was diluted 5 times with a saturated boric acid solution, and the solution was dropped onto the sample, and the state of remaining glue was determined based on the coloring state.

It is divided into 10 stages, with the size coloring state of the untreated fabric being 10 and the coloring state of the completely desizing fabric being O, and it is usually satisfactory commercially if it shows 3 or less. (5) The state of the untreated fibers was divided into 10 grades, with the state of the untreated fibers being rated as 10 and the state of the fibers from which the remaining cotton fragments had been completely removed as O.

Normally, commercially, a value of 1 or less is required. Example 1 A 100% cotton gold cloth fabric was treated with boiling water for 10 seconds.*Then it was scorched with a mangle to a squeezing rate of 80%, cooled, and then immersed in a peroxide bleaching solution with the composition shown in Table 1. Narrow down to the aperture rate.

After that, cover it with a polyethylene sheet to prevent it from drying out and leave it in a room at a constant temperature for a certain period of time. Thereafter, the gold cloth was washed and dried, and various items were measured. The results are shown in Table 1. Comparative Example 1 A high-temperature continuous bleaching method in which desizing, scouring, and bleaching are performed in separate steps A 100% cotton gold cloth fabric was treated with DuPont's Rapid Bleach Process based on the Rapid Bleach Process recipe, and a comparison with Examples was made. I did it.

The results are shown in Table 1. Example 2 Tetoron (65)/cotton (35) poplin fabric was treated with hot water for 10 seconds, then squeezed with a mangle to a squeezing rate of 80%, and immersed in a peroxide bleaching solution having the composition shown below. Mangle to narrow down to a constant aperture rate.

After that, cover it with a polyethylene sheet to prevent it from drying out and leave it in a room at a constant temperature for a certain period of time. Thereafter, the Tetoron/cotton poplin fabric was washed and dried, and various items were measured. The results are shown in Table 2. Common conditions variation conditions The addition of phosphate, phosphate hydrogen peroxide adduct, and persulfate was changed as shown in Table 2 Comparative Example 2 High-temperature continuous bleaching method in which desizing, scouring, and bleaching are performed in separate steps DuPont Tetoron (65)/cotton (35) poplin fabric is made using our company's rapid bleaching process.
It was processed based on the bleach process prescription and compared with the examples.

The results are shown in Table 2. Comparative Example 3 The 100% cotton gold cloth fabric of Example 1 was treated with hot water for 10 seconds, then squeezed with a mangle to a squeezing rate of 80%, cooled, and immersed in a peroxide bleaching solution having the composition shown in the table below. Mangle to narrow down to a constant aperture rate.

Claims (1)

[Claims] 1 pH 11.5-12.5, Mg^+^+ 20-2
00 ppm peroxide in 35% H_2O_2 20-7
The fibers are passed through a peroxide bleaching solution containing 0cc/l, and the peroxide bleaching solution is absorbed so that the squeezing rate is 75-175% of the fiber weight, and the resulting wet fibers are heated at room temperature to 50%. A one-bath desizing, scouring, and bleaching method for fibers, which is characterized by leaving the fibers for 5 hours or more at a temperature of ℃.