JP2011006813A - Method for bleaching cellulose fiber product - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for bleaching, by which cellulose fiber products after the bleaching hardly show yellowing even if they are exposed with heat, etc.SOLUTION: This method for bleaching is performed by using an Obermaier dyeing machine. The Obermaier dyeing machine is equipped with a tube having an ozonic water-flowing hole in the inside. By filling the cellulose fiber products such as cotton around the tube, a cellulose fiber product layer is formed. Then, the ozonic water is allowed to pass many times toward the outer periphery of the cellulose fiber product layer from the flowing hole to bleach the cellulose fiber products. Here, the concentration of the ozone in the ozonic water is adjusted at 1-9 mg/L and its temperature at 0-40°C. Also, the time for reaching of the ozonic water to the cellulose product layer from the flowing hole is set to be within 5 min. Further, the bleaching time of the cellulose fiber products by the ozonic water is set to be within 60 min. Thereby, the cellose fiber products hardly showing the yellowing are obtained.

Description

  The present invention relates to a method for bleaching cellulose fiber products such as cellulose fiber cotton, cellulose fiber yarn, cellulose fiber knitted fabric or cellulose fiber nonwoven fabric, and in particular bleaching of natural cellulose fiber (cotton) products and regenerated cellulose fiber (rayon) products. It is about the method.

  Conventionally, cellulose fiber products have been mainly oxidative bleaching with a halogen-based oxidizing agent such as sodium hypochlorite, sodium chlorite, or sodium chlorate. However, these oxidizing agents have recently become sources of AOX, which is a precursor of dioxins, so that bleaching with hydrogen peroxide is frequently used in place of these oxidizing agents.

  However, since hydrogen peroxide is inferior in oxidizing power to halogen-based oxidizing agents, there is a case where sufficient whiteness of a product cannot be obtained. If sufficient whiteness is to be obtained, severe manufacturing conditions of high temperature and high pressure are required, which causes a disadvantage that energy consumption is high and manufacturing cost is high. In addition, since caustic soda and other auxiliaries are used as a hydrogen peroxide decomposing agent, there is also a disadvantage that the environmental load of waste water is high. Furthermore, the activated sludge failure due to residual hydrogen peroxide occurs and the efficiency of wastewater treatment is low, so that the cost of wastewater treatment is high.

In order to solve the above disadvantages, it has been proposed to bleach cellulose fiber products using ozone water (ozone-containing water) (Patent Document 1). The technique described in Patent Document 1 bleaches cellulose fiber products using, for example, ozone water whose ozone concentration is adjusted to 10 to 300 g / Nm ³ (10 to 300 mg / L) using an Overmeier dyeing machine. It is to try.

Japanese Patent No. 4192201 (Claims)

  However, the technique described in Patent Document 1 has only obtained a cellulose fiber product that is prone to yellowing because the ozone concentration of the ozone water used is too high. The reason for this is as follows. That is, natural cellulose fibers and regenerated cellulose fibers contain low molecular weight cellulose and various impurities together with high molecular weight cellulose. Here, examples of the various impurities include low-polymerization polysaccharides such as hemicellulose, lignocellulose, and pectin, nitrogen-containing compounds such as proteins, lignin, cutin, and wax. When such low molecular weight cellulose and various impurities come into contact with ozone water having a high ozone concentration, they are easily attacked by ozone, and the functional groups having high reactivity remain at the molecular ends due to ozone. The remaining functional group is oxidized by heat, ultraviolet rays, or the like during post-processing or use of the cellulose fiber product after bleaching, and a conjugated double bond is generated, so that yellowing easily occurs.

  Therefore, an object of the present invention is to provide a bleaching method that hardly causes yellowing even when a cellulose fiber product after bleaching is exposed to heat or ultraviolet rays.

  The present invention treats a cellulose fiber product under specific conditions using ozone water having a low ozone concentration, thereby decomposing and bleaching only the pigment in the cellulose fiber product by an oxidative action, and the molecular weight in the cellulose fiber product. Low cellulose and various impurities are less susceptible to attack by ozone.

  That is, according to the present invention, after a cellulose fiber product layer is provided around a tube having an ozone water circulation hole on the outer wall, ozone water is repeatedly applied from the ozone water circulation hole of the tube toward the outer periphery of the cellulose fiber product layer. In the method of bleaching the cellulose fiber product by passing the ozone water, the ozone concentration of the ozone water is 1 to 9 mg / L and the temperature is 0 to 40 ° C., and the ozone water is introduced into the cellulose from the ozone water circulation hole. The method for bleaching a cellulose fiber product is characterized in that the time to reach the outer periphery of the fiber product layer is within 5 minutes, and the bleaching time of the cellulose fiber product layer with the ozone water is within 60 minutes. is there. Instead of passing ozone water from the ozone water circulation hole of the tube toward the outer periphery of the cellulose fiber product layer, the passing direction of ozone water may be reversed. That is, ozone water may be passed from the outer periphery of the cellulose fiber product toward the ozone water circulation hole of the tube.

  In addition, low molecular weight cellulose and various impurities may be attacked by ozone. Therefore, the cellulose fiber product after the bleaching treatment with ozone water may be crosslinked with a crosslinking agent, and cellulose having a low molecular weight or functional groups at the molecular ends of various impurities may be bonded with the crosslinking agent. By the crosslinking treatment with such a crosslinking agent, the cellulose fiber product after bleaching is hardly yellowed.

  As the cellulose fiber product used in the present invention, cellulose fiber cotton, cellulose fiber yarn, cellulose fiber knitted fabric, cellulose fiber nonwoven fabric or the like is used. In particular, cotton cotton and rayon cotton are used. Further, in the case of cotton cotton, it is possible to use non-defatted raw cotton or raw cotton after being degreased. However, in order to obtain a high whiteness, it is preferable to use degreased raw cotton.

  In the method for bleaching a cellulose fiber product according to the present invention, a cellulose fiber product layer is provided around a tube having an ozone water circulation hole on the outer wall, and ozone water passes through the cellulose fiber product layer from the inside to the outside or from the outside to the inside. It is a method to make it. For example, the ozone water is ejected from the ozone water circulation hole of the pipe, and the ozone water is recovered from the outer periphery of the cellulose fiber product layer, or the ozone water is ejected from the outer periphery of the cellulose fiber product layer. Is recovered from the ozone water circulation hole of the tube, and the ozone water is passed through the cellulose fiber product layer to perform bleaching. Specifically, an overmeier dyeing machine, a cheese dyeing machine, or a beam dyeing machine is used. In the case of an overmeier dyeing machine, a cellulose fiber product layer is provided by filling cellulose fiber cotton around the tube. In the case of a cheese dyeing machine, a cellulose fiber product layer is provided by winding cellulose fiber yarns around the tube several times. In the case of a beam dyeing machine, a cellulose fiber product layer is provided by winding a cellulose fiber knitted fabric or cellulose fiber nonwoven fabric several times around a tube.

  One of the features of the present invention is that the ozone concentration of ozone water used for bleaching is 1 to 9 mg / L and the temperature is 0 to 40 ° C. When the ozone concentration is less than 1 mg / L, the decomposition of the pigment due to the oxidizing action of ozone becomes insufficient, and the treatment time with ozone water becomes longer, so the productivity is lowered. On the other hand, if the ozone concentration exceeds 9 mg / L, cellulose having a low molecular weight and various impurities in the cellulose fiber product are likely to be attacked by ozone and easily yellow after bleaching. If the temperature of the ozone water is less than 0 ° C., it is difficult to use because it may freeze. On the other hand, when the temperature of the ozone water exceeds 40 ° C., the self-decomposition rate of ozone is increased, cellulose having a low molecular weight and various impurities are easily attacked by ozone, and yellowing after bleaching is not preferable. In addition, the most preferable range of the temperature of ozone water is 10-25 degreeC.

  Another feature of the present invention is that ozone water passes through the cellulose fiber product layer within 5 minutes. That is, the time for the ozone water to reach the outer periphery of the cellulose fiber product layer from the ozone water circulation hole is within 5 minutes, or the time for the ozone water to reach the ozone water circulation hole from the outer periphery of the cellulose fiber product layer is 5 minutes. It is within. When this time exceeds 5 minutes, ozone is consumed by the time ozone water passes through the cellulose fiber product layer, and uniform bleaching cannot be performed as a whole. In addition, in a part of the cellulose fiber product layer initially in contact with ozone water, cellulose having a low molecular weight and various impurities are easily attacked by ozone, and yellowing after bleaching is not preferable. For example, when passing ozone water from the ozone water circulation hole toward the outer periphery of the cellulose fiber product layer, if it is in contact with ozone water for more than 5 minutes only inside the cellulose fiber product layer, only this inside is excessive. It will react with ozone. Therefore, on this inner side, cellulose having a low molecular weight and various impurities in the cellulose fiber product are easily attacked by ozone, and easily yellow after bleaching. This transit time is preferably within 1 minute, and most preferably within 30 seconds.

  Still another feature of the present invention is that the bleaching time of the cellulose fiber product layer with ozone water is within 60 minutes. The ozone water passes through the cellulose fiber product layer within 5 minutes, and this is repeated many times. For example, ozone water passes through the cellulose fiber product layer several to several hundred times. If the bleaching time exceeds 60 minutes, the reaction with ozone becomes excessive, cellulose having a low molecular weight and various impurities are easily attacked by ozone, and yellowing after bleaching is not preferable. The bleaching time is preferably within 30 minutes.

  After the bleaching is finished, it is preferable to carry out various post-processing in the present invention. The present invention is to obtain a cellulose fiber product that is less susceptible to yellowing by setting the ozone concentration and temperature of ozone water within a certain range, and the passage time and bleaching time of ozone water in the cellulose fiber product layer within a certain range. . However, in cellulose fiber products, low molecular weight cellulose and various impurities that have been attacked by ozone to some extent, that is, low molecular weight cellulose and various impurities having highly reactive functional groups at the molecular ends remain. There is a possibility. Therefore, it is preferable to bind cellulose functional groups at molecular ends or functional groups at molecular ends and cellulose by treating the bleached cellulose fiber product with a crosslinking agent. Such cross-linking treatment makes it difficult for the functional group at the molecular end to be oxidized, making it difficult for conjugated double bonds to occur, and further preventing yellowing. As the crosslinking agent, an epoxy compound such as epichlorohydrin, a dicarboxylic acid such as oxalic acid, or a dialdehyde compound such as glutaraldehyde can be employed. In addition, such a crosslinking agent is generally adjusted to an aqueous solution and can be subjected to a crosslinking treatment on the cellulose fiber product. The concentration of the aqueous solution is preferably about 0.001 to 1.0 mol / L, and more preferably about 0.05 to 0.1 mol / L.

  In addition, as other post-processing, in order to wash away low molecular weight cellulose and various impurities, the cellulose fiber product is treated with warm water of 80 ° C. or higher, or a caustic soda aqueous solution having a concentration of 100 g / L or lower at 80 ° C. or higher. Cellulose fiber products may be processed. Further, in order to oxidize cellulose having a low molecular weight or a functional group at the molecular end of various impurities, it may be treated with an oxidizing agent. As the oxidizing agent, a peracid such as peracetic acid, perlactic acid or persulfuric acid is used. The oxidizing agent is used after being adjusted to an aqueous solution having a concentration of about 0.001 to 1.0 mol / L, more preferably about 0.05 to 0.1 mol / L. Furthermore, in order to reduce the functional group at the molecular end of cellulose having a low molecular weight or various impurities, a treatment with a reducing agent may be performed. As the reducing agent, dihydroxybenzene such as hydroquinone is used. Such a reducing agent is used after being adjusted to an aqueous solution having a concentration of about 0.001 to 1.0 mol / L, more preferably about 0.05 to 0.1 mol / L.

  As described above, the method for bleaching cellulose fiber products according to the present invention uses ozone water having a relatively low ozone concentration, adjusts the temperature of ozone water to a certain range, and uses ozone water in the cellulose fiber product layer. By setting the passage time within a certain range and setting the total bleaching time within a certain range, there is an effect that a cellulose fiber product that hardly yellows after bleaching can be obtained.

  Furthermore, even after bleaching, if a crosslinking treatment is performed with a crosslinking agent, low molecular weight cellulose having a highly reactive functional group at the molecular end and various impurities may remain in the cellulose fiber product due to the attack of ozone. A cellulose fiber product that hardly yellows can be obtained. In other words, functional groups with high reactivity are bonded to each other by a cross-linking agent or between functional groups and cellulose, and are not easily oxidized by heat or ultraviolet rays, conjugated double bonds are less likely to occur, and yellowing is less likely to occur. That is the effect.

Example 1
[Bleaching process]
First, a cylindrical overmeier dyeing machine having an inner volume of 12 L and an inner diameter of 260 mmφ was prepared. In the Overmeyer dyeing machine, a pipe having a flow hole in the outer wall is provided. This overmeyer dyeing machine was filled with 1 kg of degreased cotton raw cotton dust removed with a card, and a cotton raw cotton layer was provided around the tube. Thereafter, the overmeier dyeing machine was filled with deionized water at 15 ° C.
On the other hand, 45 L of deionized water is filled in the buffer tank, and deionized water is sent from the buffer tank at a rate of 20 L / min with a mixing pump. Ozone was blown at 1 L / min, gas-liquid contact was made with a mixing pump, and after the gas-liquid separation, normal temperature ozone water having an ozone concentration of 5 mg / L was prepared. And this ozone water was supplied to the pipe | tube provided in the over Meyer dyeing machine, and it was made to pass and discharge | emit toward the outer periphery of the cotton raw cotton layer. The discharged ozone water was collected in a buffer tank and circulated, and ozone water was passed through the cotton raw cotton layer many times to supply ozone water for 30 minutes. Here, the time for the ozone water supplied from the circulation hole of the tube to reach the outer periphery of the cotton raw cotton layer was 20 seconds. As described above, the cotton raw cotton was bleached.

[Post-processing]
After finishing the bleaching process, fresh Deionized water was filled into the Overmeier dyeing machine. Then, steam was introduced into the jacket of the overmeier dyeing machine and heated, the deionized water was heated to 105 ° C., and deionized water was circulated in the overmeyer dyeing machine for 5 minutes. Thereafter, the solution was drained to obtain cotton bleached cotton.

Example 2
After finishing the same bleaching step as in Example 1, 1 g / L of caustic soda aqueous solution was filled in the Overmeier dyeing machine. Then, steam was introduced into the jacket of the overmeier dyeing machine and heated, the caustic soda aqueous solution was heated to 90 ° C., and the caustic soda aqueous solution was circulated in the overmeyer dyeing machine for 5 minutes, and then the caustic soda aqueous solution was drained. Thereafter, room temperature deionized water was filled in the Overmeier dyeing machine and circulated for 5 minutes. And after deionized water was drained, normal temperature deionized water was again filled in the Overmeier dyeing machine and circulated for 5 minutes. Thereafter, the solution was drained to obtain cotton bleached cotton.

Example 3
After finishing the same bleaching step as in Example 1, 0.9 g / L (0.01 mol / L) of epichlorohydrin aqueous solution (crosslinking agent aqueous solution) at room temperature was filled in the Overmeyer dyeing machine, and this was carried out in the Overmeyer dyeing machine. After circulating for 5 minutes, the epichlorohydrin aqueous solution was drained. Thereafter, room temperature deionized water was filled in the Overmeier dyeing machine and circulated for 5 minutes. And after deionized water was drained, normal temperature deionized water was again filled in the Overmeier dyeing machine and circulated for 5 minutes. Thereafter, the solution was drained to obtain cotton bleached cotton.

Example 4
Instead of 0.9 g / L (0.01 mol / L) room temperature epichlorohydrin aqueous solution (crosslinking agent aqueous solution), 0.9 g / L (0.01 mol / L) room temperature oxalic acid aqueous solution (crosslinking agent aqueous solution) is used. Otherwise, cotton bleached cotton was obtained in the same manner as in Example 3.

Example 5
Instead of 0.9 g / L (0.01 mol / L) normal temperature epichlorohydrin aqueous solution (crosslinking agent aqueous solution), 0.6 g / L (0.01 mol / L) normal temperature glutaraldehyde aqueous solution (crosslinking agent aqueous solution) was used. Cotton bleached cotton was obtained by the same method as in Example 3 except that it was used.

Example 6
Instead of 0.9 g / L (0.01 mol / L) room temperature epichlorohydrin aqueous solution (crosslinking agent aqueous solution), 0.8 g / L (0.01 mol / L) room temperature peracetic acid aqueous solution (oxidant aqueous solution) was used. Cotton bleached cotton was obtained by the same method as in Example 3 except that it was used.

Example 7
Instead of 0.9 g / L (0.01 mol / L) normal temperature epichlorohydrin aqueous solution (crosslinking agent aqueous solution), 1.1 g / L (0.01 mol / L) normal temperature hydroquinone aqueous solution (reducing agent aqueous solution) is used. Otherwise, cotton bleached cotton was obtained in the same manner as in Example 3.

Example 8
After finishing the same bleaching step as in Example 1, room temperature deionized water was filled in an Overmeier dyeing machine and circulated for 5 minutes. Thereafter, the solution was drained to obtain cotton bleached cotton.

The following processing was performed on the cotton bleached cotton obtained in Examples 1-8. And the cotton raw cotton after a process was measured with the Lab color system for L value, a value, and b value. The results are shown in Table 1.
[Air drying]
Cotton raw cotton was dried by blowing air using a fan in a room temperature atmosphere. The dried cotton bleached cotton was measured for color.
[Dry]
Cotton raw cotton was placed in an atmosphere of 105 ° C. for 10 minutes and dried. The dried cotton bleached cotton was measured for color.
[Sterilization]
The cotton raw cotton was placed in a 105 ° C. atmosphere for 10 minutes to dry, and then placed in a 115 ° C. atmosphere for 20 minutes for sterilization. The sterilized cotton bleached cotton was measured for color.

[Table 1]
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
Air-drying Bacteria
──────── ──────── ────────
L value a value b value L value a value b value L value a value b value ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ ━━━━━
Example 1 92.1 1.2 -0.1 92.0 1.0 1.0 91.7 0.8 1.9
Example 2 92.2 0.9 -0.3 91.6 0.9 0.9 91.4 0.7 1.8
Example 3 91.6 0.9 0.1 91.5 0.8 0.2 91.3 0.6 0.3
Example 4 91.2 1.0 -0.1 91.0 0.9 0.1 90.9 0.8 0.3
Example 5 92.1 0.8 0.2 92.1 0.7 0.2 91.9 0.5 0.3
Example 6 91.9 1.0 -0.1 91.8 0.8 0.1 91.7 0.7 0.2
Example 7 91.8 1.1 -0.2 91.8 1.0 0.1 91.6 0.8 0.2
Example 8 92.2 0.9 0.1 90.3 0.9 3.2 88.3 0.6 5.2
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━

  From the results of Table 1, the cotton bleached cotton obtained in Examples 1 to 8 showed little yellowing even when heated after bleaching. In particular, Examples 1 to 7, which were sufficiently post-processed, had less yellowing than Example 8 which was insufficiently post-processed.

Claims (4)

After providing the cellulose fiber product layer around the tube having ozone water circulation holes on the outer wall, by passing ozone water many times from the ozone water circulation hole of the tube toward the outer periphery of the cellulose fiber product layer, In a method of bleaching the cellulose fiber product,
The ozone concentration of the ozone water is 1-9 mg / L and the temperature is 0-40 ° C.
The time for the ozone water to reach the outer periphery of the cellulose fiber product layer from the ozone water circulation hole is within 5 minutes, and
A method for bleaching a cellulose fiber product, wherein the bleaching time of the cellulose fiber product layer with the ozone water is within 60 minutes. After providing a cellulose fiber product layer around a tube having ozone water circulation holes on the outer wall, by passing ozone water many times from the outer periphery of the cellulose fiber product toward the ozone water circulation holes of the tube, In a method of bleaching cellulose fiber products,
The ozone concentration of the ozone water is 1-9 mg / L and the temperature is 0-40 ° C.
The time for the ozone water to reach the ozone water circulation hole from the outer periphery of the cellulose fiber product layer is within 5 minutes, and
A method for bleaching a cellulose fiber product, wherein the bleaching time of the cellulose fiber product layer with the ozone water is within 60 minutes.   The method for bleaching a cellulose fiber product according to claim 1 or 2, wherein a degreased natural cellulose fiber is used as the cellulose fiber.   The method for bleaching a cellulose fiber product according to any one of claims 1 to 3, wherein the cellulose fiber product after bleaching with ozone water is subjected to a crosslinking treatment with a crosslinking agent.