JPS6147870A - Bleaching of cellulosic knitted fabric - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a novel bleaching method for cellulose-based knitted and woven fabrics, in which the treatment involves bleaching at 100°C.
By using wet saturated steam and controlling the filling ratio of the material to be bleached in the wet saturated steam treatment chamber, efficient bleaching can be achieved in a short time.

For the conventional bleaching of cellulose-based knitting and textiles using sodium chlorite, titanium baths are used to suppress the deoxidization of bleached substances and to eliminate white melon under a certain condition. The item to be bleached is immersed in this and the bath temperature is 100℃.
I was processing it by setting it so that it was. However, with this method, there is a limit to the heat retention and sealing mechanism, so the liquid temperature may drop to 9.
The temperature is only 5 to 98°C, and as a result, bleaching has to be carried out over a relatively long time of 30 to 40 minutes, which not only leads to poor production efficiency but also to difficulties in continuous production.

On the other hand, I used a high pressure steamer to shorten the time by 130 hours.
A method of processing at a high temperature of -150°C has also been attempted, but
In terms of equipment, high-pressure sealing technology is difficult, there are problems with the durability of the equipment, there are problems with controlling the decomposition of sodium chlorite, there are problems with fiber embrittlement due to high temperatures, and there are also problems with cotton scum called scum, which causes sunspots. There are still many issues to be solved before it can be put into practical use.

The present invention provides a new bleaching method that eliminates the drawbacks of the conventional method, and is aimed at obtaining a high-quality bleached product in a short time.

However, in this method, the material to be bleached, which has been wet-treated in a solution of sodium chlorite exhibiting acidity, is
The method is characterized in that the material to be bleached is introduced into a wet saturated steam chamber of C, and the filling rate of the material to be bleached in the wet saturated steam chamber is adjusted to be 10% or more.

This will be explained in detail below.

Figure 1 shows an example of an apparatus for carrying out the present invention, in which the main mechanisms are a sodium chlorite immersion tank (6) and a saturated steam treatment chamber (8), which are arranged in series. .

First, the knitted or woven fabric (1) to be bleached is pulled out from the reels (3) and (4) by the nip rotation of a pair of pull-out rollers (2), and the chlorine is passed through the shooter (5). Sodium soak [sent to 40(6).

The sodium chlorite solution 4o (6) contains a sodium chlorite solution whose pH has been adjusted to the acidic side, and after a sufficient soaking time for it to penetrate into cotton and textiles, it is drawn out from the tank and squeezed. After being squeezed by a roller (7), it is sent to a saturated steam treatment chamber (8). The saturated steam treatment chamber (8) is composed of a reel (9), a roller (10), a shake-off device (11), and a J-shaped box (12), and includes a squeezing roller (7) and a Jfi box (12) provided on the inlet side.
2) The structure is sealed by a main sealing plate (14) immersed in 41:1 water (13) on the outlet side, and a heating mechanism using steam (15) is provided inside the room.

However, the knitted fabric (1) soaked in the sodium chlorite solution is accumulated and retained in the saturated steam treatment chamber (8), particularly in the J-shaped box (12), heat-treated, and then taken out and washed with hot water and then with water. Ru.

In this series of continuous methods, the heat source in the sealed saturated steam treatment chamber (8) is 100°C.
The method is characterized in that it uses wet saturated steam, and that the filling rate of the material to be bleached is controlled to 10% or more relative to the entire volume of the wet saturated steam treatment chamber. It is.

This will be explained below using an example.

<Example> The present invention, which was processed under the conditions shown in the table below using a fabric milled with 40 count cotton yarn, showed good results as shown in the evaluation in Table 1.

The apparatus shown in FIG. 1 was used, and an aqueous solution of NaC1Ox with a concentration of 25 vH was used in both the control and the examples.

In addition, the control plot was made using the conventional batch method and the bath ratio was 1:4.
The specimens were immersed in an immersion bath under the following conditions and then treated at the heating temperature and time shown in the table.

In addition, the present invention in the heating chamber section of the table is based on the treatment conditions in the saturated steam treatment chamber.Furthermore, the white discoloration in the evaluation is the cutting strength after the filament is unraveled.

(The following is a blank space) As is clear from the above results, the present invention was able to obtain results comparable to the conventional methods in an extremely short time compared to the conventional methods.

In the present invention, the acidic sodium chlorite solution is one that has been made acidic using sulfur, etc. in order to perform acid activity, and has a pH of 5.0 or less, preferably 2.5 to 4.
．． It is desirable that the temperature be in the range of 0. Such conditions are related to the heat treatment time, but in the range that allows i-line treatment for a short time of 1 to 15 minutes, white discoloration over a certain period is obtained and embrittlement is prevented. In order to achieve this, it is desirable that the above conditions be met.

Furthermore, the use of wet saturated steam at 100°C is an important requirement of the present invention, and to explain this based on Figure 2, as water is heated at normal pressure, the temperature will decrease as shown in the figure. It rises and reaches point A-B. Ts is the boiling point at this normal pressure, which is about 100°C. This water boils and solidifies from point B, and when the generated steam is further heated, the temperature of the steam does not change and the water content in the steam gradually decreases until D
When the temperature of the steam reaches the point , and further heating from this point, the temperature of the steam rises. In this water change, A-B is hot water, B is saturated hot water, D is dry saturated steam, and E is the state of heated steam. In the present invention, wet saturated steam at 100°C is B-
State the state of D.

The present invention utilizes the condition B-D, and according to this, a certain level of whitening can be achieved in an extremely short period of time without the need for a particularly high-performance high-pressure container, and embrittlement can be prevented. This state is utilized by using live steam or a heat source such as infrared rays or microwaves.

In addition, the filling rate in the wet saturated steam treatment chamber was set to 10
% or more is to effectively utilize the generated chlorine gas, and treatment within this range makes it possible to remove scum, which was previously impossible. Therefore, although it is related to the treatment time and pH, it is necessary to perform the treatment under such conditions in order to remove the dross and obtain a bleached product of good quality.

In addition, in the wet treatment in an acidic sodium chlorite solution in the present invention, it is necessary to take sufficient timing to allow the solution to sufficiently penetrate into the object to be bleached. The sodium solution is at least 0.5% g w f of 100% pure sodium chlorite.
It is necessary to process the material with an appropriate concentration by adding an appropriate aperture so that the amount of adhesion is 0.5% owf.
The present invention uses sodium chlorite to produce a bleaching product that is comparable to conventional methods, such as white discoloration that exceeds a certain level, such as when the tf/\interwhiteness cannot be reduced to more than 1°. can be obtained and can be processed in a short time.
For this purpose, use a sealed continuous steamer, etc. 1.
bleached product can be obtained continuously.

[Brief explanation of drawings]

FIG. 1 is a side view showing an example of an apparatus for implementing the present invention. FIG. 2 is an explanatory diagram of saturated steam used in the present invention. (6)-m-Sodium chlorite immersion tank (8)--Saturated steam treatment chamber

Claims (1)

[Claims] The object to be bleached that has been wet-treated in an acidic sodium chlorite solution is introduced into a wet saturated steam chamber at 100°C,
The filling rate of the material to be bleached in such a wet saturated steam chamber is 1.
A method for bleaching cellulose-based knits and textiles, which comprises adjusting and processing the cellulose-based knits and textiles so that the concentration is 0% or more.