JP2815347B1 - Method of bleaching long fabric - Google Patents

Abstract

Abstract: Using the reducing power of NaBH ₄ (sodium borohydride acid) to the fabric, its activation with enhanced by the action of an alcohol such as methanol or ethanol, the reaction to control the strong activation radical The effect of (1) is to shorten reaction time and save heat energy, and also to obtain a high degree of whiteness while improving texture by avoiding embrittlement and hardening of fibers. SOLUTION: The bleaching method for a long-length fabric is characterized in that the bleaching reaction is performed by using a method of appropriately taking wet heat or a reaction time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a bleaching method as a pre-treatment before a post-processing such as dyeing of a woven or knitted fabric produced industrially,
In particular, the present invention relates to a bleaching method for solubilizing impurities (such as contaminants, pigments, and fats and oils) contained in fabric fiber using a solution containing sodium borohydride as a main component, and removing the impurities from the fabric. Things.

[0002]

2. Description of the Related Art Fabrics are usually decomposed by an enzyme or an oxidizing agent in a desizing step to reduce the molecular weight, solubilize and dissolve in hot water, and then remove an adhesive agent attached in a weaving step. The oils and fats, impurities, etc. are saponified with an alkali agent and solubilized and removed in hot water, and as a final step of pretreatment, a colored dye component is treated with an oxidizing agent and a reducing agent to form a conjugated double bond ( -N = N-) and the like are cut and bleached, and then subjected to subsequent post-treatments such as dyeing.

[0003] Oxidation and reduction treatments at the time of the above-mentioned bleaching are carried out by boiling with these chemicals for about 1 to 2 hours and subsequent washing, or padding a solution of these chemicals with an appropriate concentration to 80 to 80 wt. After adhering 100% by weight to the fabric, the mixture is steamed in a steam atmosphere of 95 ° C. or higher for about 30 to 1 hour to promote the reaction and perform bleaching.

[0004]

However, in this conventional bleaching method, the activation of the oxidizing agent and the reducing agent is promoted by the activation of the oxidizing agent and the reducing agent by the energy given by heating the water as the solvent. In this conventional bleaching method, water having a large heat capacity must be heated to the boiling point, and the time required for the reaction needs a long time. However, there is a problem that a large amount of heat is required to maintain the temperature.

As the oxidizing agent used for the above-mentioned bleaching, hydrogen peroxide is generally used. However, this hydrogen peroxide may cause the fiber to become brittle due to a rapid reaction. The decomposition must be delayed for a long time and the reaction must take place over a long period of time.The steam and heat must be used over a long period of time, so a large capacity vessel is required and a lot of energy (steam ) Is required, and the finished fiber becomes hard.

In the conventional bleaching treatment, hydrosulfite, SO ₂ generated by a chemical reaction from a compound, or the like is used as a reducing agent. It was not effective enough.

The present invention has been made by paying attention to each problem in the above-mentioned conventional bleaching method. In other words, using the reducing power of NaBH ₄ (sodium borohydride), which has recently attracted attention in organic synthetic chemistry, for fabrics, its activation is further enhanced by the action of alcohol such as methanol or ethanol, and the reaction is controlled. By the action of strong activated radicals, a bleaching method that can obtain high whiteness while shortening the reaction time and saving heat energy, and further improving the texture by avoiding embrittlement and hardening of the fiber For the purpose of providing.

[0008]

In order to achieve the above object, according to the present invention, a long woven knitted fabric impregnated with an aqueous solution containing sodium borohydride and an alcohol is bleached by being left in the atmosphere. It is characterized in that it is a method for bleaching a long fabric to be reacted.

A second aspect of the present invention is a method for bleaching a long woven knitted fabric impregnated with an aqueous solution containing sodium borohydride and an alcohol and causing a bleaching reaction using moist heat.

According to a third aspect of the present invention, a long woven knitted fabric impregnated with an aqueous solution of sodium borohydride and then impregnated with an aqueous solution of alcohol is left in the air after wrapping with a plastic film to prevent evaporation of water. And a bleaching method for a long fabric to be subjected to a bleaching reaction.

A fourth aspect of the present invention is a method for bleaching a long woven knitted fabric which is impregnated with an aqueous solution of sodium borohydride and then impregnated with an aqueous solution of an alcohol, and is subjected to a bleaching reaction using moist heat. And

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail based on an embodiment shown in the drawings.

In FIG. 1, reference numeral 1 denotes a long woven or knitted fabric to be bleached (hereinafter simply referred to as a fabric);
Is a padding tank for applying and impregnating the bleaching treatment liquid to the fabric. The padding tank 2 is desirably a liquid tank having a capacity as small as possible in order to always apply fresh processing liquid to the cloth 1. Reference numeral 3 denotes a pair of squeezing rolls arranged above the padding tank 2, 4 denotes a reaction processing chamber held in a steam chamber by steam supplied from a steam supply pipe 5, and 6 denotes a reaction processing chamber 4. 1 shows a fabric guide roll that has been used.

In order to perform the bleaching treatment of the cloth 1 using the apparatus having the above configuration, first, the bleaching treatment liquid 7 is put into the padding tank 2. The bleaching solution is an aqueous solution in which 10% by weight of sodium borohydride (NaBH ₄ ) and 10% by weight of alcohols are mixed.

The fabric 1 to be treated is immersed in the bleaching solution 7 and then squeezed by the squeezing roll 3 and then subjected to a wet heat treatment in the reaction treatment chamber 4 at a timing of about 1 to 3 minutes to bleach. A reaction is made. The cloth taken out of the reaction chamber 4 is transferred to a washing step (not shown) to complete the bleaching process.

In the embodiment shown in FIG. 1, the cloth 1 transferred in the reaction processing chamber 4 is transferred in a tensioned state by the guide roll 6, but the cloth 1 is stretched like a knit. For fabrics that are likely to be generated, for example, as shown in FIG. 2, a plurality of conveyors 8 for transferring the fabrics are vertically set in the reaction processing chamber 4 to cause the knitted fabric to be processed to grow. The bleaching process can be performed without or without impairing the texture.

In the embodiment shown in FIG. 3, the bleaching treatment is performed by using an aqueous solution of sodium borohydride 7A and an aqueous solution of alcohol 7
B, and the fabric 1 to be bleached is firstly 10% by weight.
The aqueous solution 7A to which sodium borohydride is added is impregnated in the padding tank 2A and squeezed by the squeezing roll 3, and then the aqueous solution 7B to which 10% by weight of alcohol is added is impregnated and squeezed to maintain wet heat. The bleaching process is performed in the reaction processing chamber 4. In this embodiment, the padding tank 2B containing the aqueous alcohol solution 7B is provided outside the reaction processing chamber 4, but this padding tank 2B is provided in the reaction processing chamber 4 and the reaction processing chamber 4 is provided. Within this, an alcohol aqueous solution may be applied to the fabric.

Further, in each of the above embodiments, the cloth impregnated with the treatment liquid is used in the reaction treatment chamber where the heat and humidity are maintained. However, the present invention is not limited to this. For example, as shown in FIG. The long fabric 1 impregnated with 7 may be wound around a winding drum 9, wrapped with a plastic film, and left to react in the air. In this case, a long time is required for the bleaching reaction, but it is possible to complete the bleaching. In addition, as shown in FIG. 5, a bleaching reaction is performed at a timing while alternately repeating winding and rewinding of a certain length of fabric inside a jigger 10 filled with the same processing liquid 7 as described above. You may.

Next, the operation will be described. Sodium borohydride (NaBH ₄ ) dissolves well in water and gradually reacts with water while generating hydrogen. For this reason, solutions stabilized by adding an alkali are commercially available, but even this alkali solution can easily reduce aldehydes and ketones.

4R ₂ CO + NaBH ₄ → Na [B (OCHR ₂ ) ₄ ] Na [B (OCHR ₂ ) ₄ ] + 4H ₂ O → NaB (OH) ₄ + 4R ₂ CHOH This reducing agent is soluble in methanol and ethanol and is methanol Reacts immediately with, but reacts slowly with ethanol. That is, in the case of methanol at 60 ° C. for about 25 minutes,
0% hydrogen evolution is observed. Also, it reacts violently with the methanol concentrated solution while generating heat at room temperature to generate hydrogen. On the other hand, in the case of ethanol, the concentration is 2% or less under the same conditions. However, if this is used, it can be reduced in a homogeneous solution, and there is an advantage that the reducing agent is not lost as much as methanol by a side reaction with a solvent. Taking advantage of these points, the generation (reduction) of hydrogen is controlled by using an appropriate amount of alcohol to reduce and bleach at low temperatures from cotton, which is difficult to bleach, to silk, which has low chemical resistance, and wool.

In the control of the reducing power according to the present invention, since an alcohol which is inactive to cellulose fibers and protein fibers is used, there is no oxidative damage to the fibers due to oxidative damage to the fibers by the conventional method. Therefore, the obstacle to the fiber of the main agent is minimal, and the texture is limited to only the surface layer (because the fiber is less swelled by hot water), and a good texture is obtained.

[0022]

【Example】

Example 1 10% by weight of sodium borohydride (N
aBH ₄ ) and 10% by weight of methanol in an aqueous solution containing the scoured cotton cloth padded with 2 dip 2 nip (100% squeezing rate), sealed with a polyethylene film, left for 24 hours, and then washed with hot water → surfactant After washing, washing with hot water and washing with water (hereinafter referred to as washing), it was dried.
As a result, Hunter whiteness was 91.3. Y. I (yellow index) 0.13 was obtained.

This value is a value when no fluorescent brightener is used in combination.

Note: Value of standard white plate for colorimetric reference Hunter whiteness 96.4 Y. I 0.1 Fabric used: Twill cotton cloth 40/2, warp 20/2 [Example 2] 10% by weight of sodium borohydride (N
aBH ₄ ) and an aqueous solution containing 20% by weight of ethanol,
After padding the scoured cotton fabric with 2 dips and 2 nips (squeezing rate 100%), it is placed in a steam tank for about 60 minutes for about 60 minutes.
After washing what was kept at ℃, it was dried. As a result,
Hunter whiteness 89.88. Y. I (yellow index) 0.13 was obtained.

Similarly, the hunter whiteness is 92 in E / C (50/50). Y. I (yellow index) 0.12
I got

A bleached cloth having a soft texture thicker than that of oxidative bleaching was obtained.

This value is a value when no fluorescent brightener is used in combination.

Note: Value of standard white plate for colorimetric reference Hunter whiteness 96.4 Y. I 0.1 Fabric used: E / C (50/50) Poplin 20/2 Latitude 40/20 [Example 3] 6% by weight of sodium borohydride (Na
BH ₄ ) and (aqueous solution containing 20% by weight of ethanol)
Then, a scoured wool fabric was immersed in the mixture, treated with stirring for 30 minutes, washed, and then dried. As a result, Hunter whiteness was 85.7. Y. I (yellow index) 0.14
I got

Fabric used: plain woven blanket Example 4 10% by weight of sodium borohydride (N
aBH ₄ ) and (aqueous solution containing 20% by weight of ethanol)
Then, a scoured wool fabric was immersed in the mixture, treated with stirring for 30 minutes, washed, and then dried. As a result, Hunter whiteness was 90.7. Y. I (yellow index) 0.12
I got

Fabric used: 120 cotton broad cloth, weft 120/2, warp 120/2

[0031]

As described above, according to the present invention, it is possible to obtain a high degree of whiteness, to shorten the processing time, and to obtain a soft and bulky bleaching cloth with the effect of improving the texture. it can.

Further, sodium borohydride (NaBH)
₄ ) The reduction action of methanol and water also has the property of selectively and effectively acting on ketones and acid chlorides in particular. Therefore, natural fibers containing these compounds as impurities, such as wool and silk, have been used for the conventional oxidation bleaching. The bleaching effect that the resistance is weak and the whiteness is superior to protein fibers that have been boiled and bleached with the reducing agent hydrosulfite can be obtained.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a first embodiment of an apparatus used to carry out a bleaching method according to the present invention.

FIG. 2 is an explanatory view showing a second embodiment of the apparatus used to carry out the bleaching method according to the present invention.

FIG. 3 is an explanatory view showing a third embodiment of the apparatus used to carry out the bleaching method according to the present invention.

FIG. 4 is an explanatory view showing a fourth embodiment of the apparatus used to carry out the bleaching method according to the present invention.

FIG. 5 is an explanatory view showing a fifth embodiment of the apparatus used to carry out the bleaching method according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Fabric 2 ... Padding tank 3 ... Squeezing roll 4 ... Reaction processing chamber 5 ... Steam supply pipe 6 ... Fabric guide roll 7 ... Bleaching treatment liquid 8 ... Conveyor 9 ... Winding drum 10 ... Jigger

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-55-84484 (JP, A) JP-A-49-87428 (JP, A) JP-A-54-116481 (JP, A) JP-B-42 15564 (JP, B1) (58) Field surveyed (Int. Cl. ⁶ , DB name) D06L 3/10 C11D 7/54

Claims (4)

(57) [Claims] 1. A method for bleaching a long woven fabric, wherein a long woven knitted fabric impregnated with an aqueous solution containing sodium borohydride and an alcohol is allowed to undergo a bleaching reaction in the air. 2. A method for bleaching a long woven fabric, wherein a long woven knitted fabric impregnated with an aqueous solution containing sodium borohydride and an alcohol is subjected to a bleaching reaction using moist heat. 3. A method for bleaching a long woven fabric, wherein a long woven knitted fabric impregnated with an aqueous solution of sodium borohydride and then impregnated with an aqueous alcohol solution is allowed to stand in the air to undergo a bleaching reaction. 4. A method for bleaching a long woven fabric, wherein a long woven knitted fabric which is impregnated with an aqueous solution of sodium borohydride and then impregnated with an aqueous alcohol solution is subjected to a bleaching reaction using moist heat.