JPH10158925A - Regenerated cellulose yarn excellent in dyeability and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a modified cross-section regenerated cellulose yarn, excellent in dyeability, fibrillation resistance and handle, useful for clothing, etc., by subjecting a specific spinning solution to dry spinning. SOLUTION: In producing a regenerated cellulose by using a spinning solution obtained by dissolving a cellulose in a solvent containing N-methylmorpholine-N- oxide, the cellulose is adjusted to 3-15wt.% hemicellulose content and the spinning solution is subjected to dry spinning. Preferably, the average polymerization degree of the cellulose in the spinning solution is controlled to <=400, 5-20wt.% of the cellulose has >=500 polymerization degree and a spun filament is cooled by a gas flow between a spinneret and a coagulating bath.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a regenerated cellulose fiber obtained by using a stock solution obtained by dissolving cellulose in a solvent containing N-methylmorpholine-N-oxide (hereinafter abbreviated as NMMO), and a method for producing the same. In particular, the present invention relates to a technique for obtaining a high-quality regenerated cellulose fiber having excellent dyeability, gloss, texture, and the like and improved fibril resistance.

[0002]

2. Description of the Related Art A method for producing regenerated cellulose fibers using a solvent containing NMMO has been known for a long time, as described in, for example, Japanese Patent Publication Nos. 57-11566 and 60-28848. However, the conventional production method using the above-mentioned solvent has a major drawback that the obtained regenerated cellulose fiber is liable to be fibrillated, which has been an obstacle to general use. However, this method has little adverse effect on the environment and is economically efficient.
In addition, the properties of the obtained regenerated fibers are good to some extent, so they have recently attracted attention again.

On the other hand, research on improvement of the above-mentioned problem of fibrillation has been advanced, and for example, Japanese Patent Application Laid-Open No. 8-501356.
Nos. 7,508,320 and JP-A-8-49167, some applications have been filed, but in practice, satisfactory effects have not yet been obtained on a practical scale.

[0004] When the regenerated cellulose fiber obtained by using the above-mentioned solvent is applied to the field of clothing and the like, it is important to enhance the dyeability, gloss and texture of the fiber itself or woven or knitted fabric. At present, no study has been made on the improvement of the dyeability of regenerated cellulose fibers using an NMMO-containing solvent.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above situation, and its object is to make use of the characteristics of the method for producing a regenerated cellulose fiber using the NMMO-containing solvent described above. , While further improving its maintenance characteristics, eliminating the problem of fibrillation pointed out as its drawback, providing excellent regenerated cellulose fibers with excellent dyeing properties, physical properties and texture, and stabilizing such fibers It is intended to establish a manufacturing method that can be manufactured by using the method described above.

[0006]

Means for Solving the Problems The regenerated cellulose fiber excellent in dyeability of the present invention which can solve the above-mentioned problems is a regenerated cellulose produced by using a spinning solution obtained by dissolving cellulose in a solvent containing NMMO. A characteristic feature of the fiber is that the content of hemicellulose in the regenerated cellulose fiber is set to a specific amount.

In this regenerated cellulose fiber, the average degree of polymerization of the cellulose contained in the fiber is 400 or less, and 5 to 30% by weight of the cellulose has a degree of polymerization of 5
Those having a value of 00 or more not only have excellent physical properties and appearance properties such as texture, but are also extremely excellent in fibrillation resistance, and can be widely used for clothing and the like.

The production method of the present invention is a method for producing a regenerated cellulose fiber having the above characteristics and excellent in dyeability, wherein the regenerated cellulose is produced using a spinning stock solution obtained by dissolving cellulose in a solvent containing NMMO. On the occasion, the content of hemicellulose in the regenerated cellulose fiber is 3 to 15% by weight.
There is a gist of spinning by dry-wet spinning to produce regenerated cellulose fibers. In carrying out this method, the average degree of polymerization of the cellulose in the spinning dope is suppressed to 400 or less, and 5% of the cellulose is used.
It is preferable to adjust the degree of polymerization to be not less than 500% by weight so that the fibril resistance of the obtained fiber can be increased.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors have studied various aspects of improvement in order to prevent the above-mentioned drawbacks of the prior art, in particular, fibrillation, which is pointed out in regenerated cellulose fibers using a solvent containing NMMO. I proceeded. As a result, when producing a regenerated cellulose fiber using the above-mentioned solvent, if a spinning solution that causes a pseudo-liquid crystal phenomenon in the spinning process is used, the obtained regenerated cellulose fiber will have extremely low fibrillation. We found a new fact that no one was aware of.

[0010] In addition, when the spinning solution that causes the above-mentioned pseudo liquid crystal phenomenon is used and dry-wet spinning is performed, regenerated cellulose fibers having excellent dyeing properties and extremely excellent gloss and texture can be easily obtained. I knew that.

Further studies have shown that the degree of polymerization of the cellulose dissolved in the spinning dope is extremely important in order to cause the above-mentioned pseudo-liquid crystal formation in the spinning process. What is necessary is just to use what contains the cellulose with a high degree of polymerization and the cellulose with a low degree of polymerization in a specific ratio, and when such a mixed cellulose solution is used as a stock solution for spinning, fibrillation occurs. And extremely low quality, and high-quality regenerated cellulose fibers can be obtained reliably and easily. Here, the “pseudo liquid crystal phenomenon” refers to a phenomenon in which cellulose undergoes a liquid crystal transition in a flow field or an elongation field during spinning.

Regenerated cellulose fibers spun with NMMO as a solvent have relatively good dyeing properties, even though they do not substantially contain hemicellulose, despite being basically composed of fibrils that are difficult to dye. However, it cannot be said that the dye exhaustion amount is large, but rather small compared to other cellulose fibers. As a result of earnest research on this point, the following has been found. That is, the small amount of dye exhaustion is due to the extremely small amount of dye exhaustion of the fibrils responsible for the excellent mechanical properties of the fiber. However, it is the effect of impurities such as hemicellulose and lignin segregated out of fibrils that have good dyeability. The hemicellulose segregated so as to surround the fibrils serves as a dye-dyeing seat and is effectively dyed in spite of a small amount of exhaustion as a whole, resulting in good dyeability.
Therefore, by increasing the amount of impurities, a fiber having further improved dyeing properties and improved texture can be obtained.
In particular, this effect is even more remarkable in irregular cross-section yarns and hollow fibers.

As the raw material cellulose, any general cellulose may be used. However, a pulp raw material containing a relatively large amount of hemicellulose component, for example, kraft pulp is mixed, and the content of hemicellulose contained in the fiber is 3 to 15% by weight. %. The preferred content of hemicellulose is 3 to 12% by weight, more preferably 4 to 10% by weight. When the content of hemicellulose is less than 3% by weight, the effect of improving the dyeability is not observed,
If the content is more than 10% by weight, the spinnability is reduced and the yarn properties are significantly reduced.

The regenerated cellulose fiber having the above-mentioned properties is
It is obtained by using a solvent containing NMMO, using a spinning dope in which cellulose is dissolved, and adjusting the content of hemicellulose in the cellulose to a range of 3 to 15% by weight and performing dry-wet spinning. If the average polymerization degree of the cellulose dissolved therein and the content ratio of the high polymerization degree cellulose are properly adjusted, a pseudo-liquid crystal phenomenon occurs in the spinning process, and a regenerated cellulose fiber excellent in fibril resistance is obtained. It becomes possible.

That is, in producing the above-mentioned regenerated cellulose fiber, the average degree of polymerization of the cellulose dissolved in the spinning solution is set to 400 or less, and the content of cellulose having a high degree of polymerization of 500 or more in the cellulose is contained. It is preferable that the ratio be within the range of 5 to 30% by weight. When a cellulose mixture having a different degree of polymerization is used, a structure in which a cellulose component having a high degree of polymerization is extended by phase separation in a spinning process to form a main chain mainly composed of a chain is obtained. It is formed, and the gaps are filled with cellulose having a low polymerization degree, and the obtained regenerated cellulose fiber forms a composite-like structure, which is considered to suppress fibrillation.

That is, the high polymerization degree cellulose is the main cause of the quasi-liquid crystalline phenomenon and converges in the longitudinal direction to take on the mechanical properties, while the low polymerization degree cellulose fills the gaps and is required for clothing such as texture. It plays a role of enhancing properties, and by its additive or synergistic effect, excellent strength properties and texture are given, and it is possible to suppress fibrillation as much as possible by a composite composite fiber structure. It becomes.

In order to ensure such a composite-like structure and facilitate the spinning operation, it is preferable to suppress the average degree of polymerization of the cellulose dissolved in the spinning solution to 400 or less. In order to surely cause the phenomenon and secure sufficient mechanical properties in the longitudinal direction as the obtained regenerated cellulose fiber, the content ratio of the high-polymerization degree cellulose having a polymerization degree of 500 or more in the cellulose is adjusted to 5% by weight or more. Is extremely effective. That is,
If the content of the cellulose having a high degree of polymerization is less than 5% by weight, the above-mentioned pseudo-liquid crystal formation phenomenon is unlikely to occur in the spinning step, and not only the effect of preventing fibrillation by phase separation becomes insufficient, but also the longitudinal dynamics. Properties are poor, while the content ratio of high polymerization cellulose having a polymerization degree of 500 or more is 30
If the content is more than 10% by weight, phase separation does not occur even if a pseudo liquid crystal phenomenon occurs in the spinning process, and it is difficult to obtain an effect of preventing fibrillation. From the above viewpoint, the more preferable content ratio of the high polymerization degree cellulose having a polymerization degree of 500 or more is in the range of 5 to 25% by weight, more preferably 5 to 20% by weight.

In the present invention, as described above, the proportion of the cellulose having a low degree of polymerization is large, and the strength of the regenerated cellulose fiber tends to be slightly lower. As a result, in the clothing use which is the main use of the present invention, As in the case of industrial materials, high fiber strength is not so required. Rather, the feeling and the fibril resistance are emphasized, so that there is no problem of insufficient strength for practical use.

The highly polymerized cellulose used in the present invention comprises:
The type of the spinning solution is not particularly limited as long as it exhibits a degree of polymerization of 500 or more, but the most common is cellulose having a degree of polymerization of 750 or more made of wood pulp. However, as long as it satisfies the above requirements for the degree of polymerization, linters and cotton fibers may be used. On the other hand, as the cellulose having a low degree of polymerization, a recovered product of rayon fiber or the like is preferably used. In addition, cellulose obtained from a recovered product such as used paper or recovered used cotton can be used. These raw celluloses are wetted with ethanol or the like, then crushed or cut and dried.

In preparing the spinning dope,
The average polymerization degree of cellulose in the stock solution is 400 or less and the content ratio of high polymerization degree cellulose having a polymerization degree of 500 or more is 5
The mixing ratio of the above-mentioned high-polymerization degree cellulose and low-polymerization degree cellulose may be adjusted so as to be in the range of 30 to 30% by weight, more preferably 5 to 25% by weight, and still more preferably 5 to 20% by weight.

As the solvent used for preparing the spinning dope, a solvent containing NMMO is used.
It is a mixed solvent of MO and water, and particularly preferred is N
It is a mixture in which the mixing ratio of MMO / water is 90/10 to 40/90 by weight.

Then, the cellulose is added to these solvents so that the concentration of the cellulose is preferably 15 to 25% by weight.
Usually, a stock solution for spinning is prepared by dissolving with a shear mixer or the like at a temperature of about 80 to 135 ° C. If the cellulose concentration of the spinning dope is too low, pseudo-liquid crystal spinning is not performed. Conversely, if it is too high, the viscosity becomes too high and spinning becomes difficult.
It is desirable to adjust the amount to be in the range of 5 to 25% by weight, more preferably 15 to 20% by weight.

Since the starting cellulose has a slight decrease in the degree of polymerization in the dissolving step, the degree of polymerization of the cellulose as defined in the present invention is measured in a state after the dissolving step, and the average degree of polymerization is high. What is necessary is just to adjust the compounding quantity of high polymerization degree cellulose and low polymerization degree cellulose used as a dissolution raw material so that the content ratio of a polymerization degree product may satisfy the above-mentioned requirements. At this time, a decrease in the degree of polymerization of cellulose during dissolution or an NMMO
It is recommended as a preferred embodiment to add a stabilizer such as, for example, hydrogen peroxide, oxalic acid or a salt thereof, gallic acid, methyl digallic acid, glycoside, etc. in order to suppress the decomposition of the compound.

A solution obtained by dissolving a cellulose raw material in a mixed solvent of NMMO and water is relatively low in viscosity, so that a high-concentration solution is easily obtained, and its viscosity is suitable for wet spinning. Journal of the Textile Society of Japan, "51, 423 (199
As described in 5).

The thus obtained solution having a high viscosity (zero shear viscosity at the dissolution temperature of about 5,000 poise or more) is defoamed by a thin film evaporator, filtered, and then supplied to a spinning section. The high-viscosity spinning solution is sent to a spinning head, metered by a gear pump, and supplied to a spin pack. The spinning temperature is preferably in the range of 90 to 135 ° C. If the spinning temperature is lower than 90 ° C, spinning becomes difficult because the dope viscosity is too high.
If the temperature is excessively higher than 5 ° C., the degree of polymerization is reduced due to decomposition of cellulose, and the physical properties, particularly tensile strength, of the obtained regenerated fiber are poor.

For the orifice used for spinning, it is effective to increase the L / D in order to increase the stability of the dope.
Then, there arises a problem that the spinning back pressure increases. Therefore, it is desirable to use a tapered orifice having a small introduction angle, and to suppress the generation of turbulence.

It is desirable that the taper angle α of the introduction portion be 45 degrees or less, more preferably 35 degrees or less. However, it is not only difficult to machine the taper angle α too much in terms of machining, but also it is difficult to reduce the taper angle α. Since turbulence tends to occur at the entrance to the introduction part and tends to impair spinnability, it is desirable to stop the flow to about 10 degrees.
A more preferable taper angle is in the range of 15 to 30 degrees in consideration of spinnability, workability, and the like.

The dope discharged from the die is stretched by a so-called air gap (a section until the dope discharged from the discharge portion enters the coagulating liquid). However, if the tapered orifice as described above is used, sufficient spinning is performed. Draft can be given, and as a result, the phenomenon of pseudo-liquid crystal formation is surely exhibited, and the fibril resistance is also enhanced.

Therefore, in practicing the present invention, in order to lower the solution viscosity of a high-viscosity spinning solution, spinning is performed at a high temperature, and coagulation is performed at a temperature lower than the spinning temperature. As described in above, it is necessary to employ a dry-wet spinning method in which an air gap is provided until the discharged dope discharged from the spinning nozzle enters the coagulation bath. That is, when such a dry-wet prevention method is employed when practicing the present invention, a high-polymerization degree cellulose in a high-concentration solution containing a high-polymerization degree cellulose and a low-polymerization degree cellulose is formed in the air gap portion. Phase transition and phase separation occur in the flow field or elongation field, and a pseudo-liquid crystal transition phenomenon occurs in this part, and the high-polymerized cellulose forms a fiber skeleton, and the regenerated cellulose obtained contains a large amount of low-polymerized cellulose. However, it shows sufficient strength. The spinning speed is not particularly limited.
m / min or more, preferably 150 m / min or more.

If the air gap is an air gap in which only a non-coagulating gas exists, such as ordinary air, the gap between the die and the coagulating liquid surface is obtained so that a large deformation rate can be obtained while suppressing molecular relaxation. May be set to about 5 to 50 mm. Alternatively, if a method of actively cooling the discharged yarn using a quench chamber or the like is employed, the air gap may be long because molecular relaxation does not occur, and this is rather preferable especially when spinning at high speed.

It is preferable to use an aqueous solution of NMMO as the coagulation bath, and it is desirable to use an aqueous solution having an NMMO concentration of 10 to 50% by weight. Then NMM
If the O concentration is less than 10% by weight, the recovery rate of the evaporating NMMO is low, which is uneconomical. On the other hand, if the O concentration is excessively higher than 50% by weight, the filament is insufficiently coagulated. A more preferred NMMO concentration in the coagulation bath is 15
-40% by weight. The preferred temperature of the coagulation bath is in the range of −20 to 20 ° C., more preferably −10 to 15 ° C. When the temperature exceeds 20 ° C., coagulation is insufficient and the fiber performance deteriorates. Excessive cooling to a temperature below this does not further enhance fiber performance, so further cooling is economically wasteful.

The yarn that has passed through the coagulation bath is subsequently sent to a washing / drying step. At this time, collecting and processing the yarn using a collecting device such as a net conveyor requires equipment. This is extremely effective for simplification. Further, in order to further facilitate collection by a net conveyor, it is also recommended as a preferable method to use a known double kickback roll or an aspirator as disclosed in Japanese Patent Publication No. 47-29926. When the obtained regenerated cellulose fibers are used as short fibers, it is also effective to provide a crimper during the process to impart expansion and contraction. As the crimper, a so-called stuffing box type crimper is preferable, but a gear crimper may of course be used. When a box-type crimper is used, it can also be used as a net conveyor collecting device.

The fiber bundle washed and dried using a net conveyor is wound up as a yarn of a predetermined fineness by a winder when it is obtained as a long fiber, and the bundled long fiber is immediately or separately cut when it is obtained as a short fiber. Can be obtained by cutting. As the cutter, a rotary cutter, a guillotine cutter or the like is generally used.

[0034]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples, and the present invention is not limited thereto. Of course, the present invention can be embodied with modifications, all of which are included in the technical scope of the present invention. In addition, the measuring method of each performance adopted in the following Examples and Comparative Examples is as follows.

[Measurement of Degree of Polymerization of Cellulose] "Polymer Material Testing Method 2" edited by The Society of Polymer Science, p. 267, Kyoritsu Shuppan (19
Measured by the copper ethylenediamine method described in 65). [Measurement of Dyeing Property] A test was conducted in accordance with JIS L-1015 7.30 dyeing rate.

[Quantitative determination method of hemicellulose]
The treatment was carried out according to 5.6β cellulose of ISP-8101-1994, and the content of hemicellulose was determined from the obtained values.

Example 1 Kraft pulp was used as cellulose, and 15 parts by weight thereof was dissolved at 110 ° C. in a mixture of 73 parts by weight of NMMO and 12 parts by weight of water to prepare a spinning dope. Using this spinning dope, dry and wet spinning was carried out under the conditions shown in Table 1, and the obtained filaments were washed with water, dried and wound up, and the physical properties and dyeing rate of each fiber were measured. I got

[0038]

[Table 1] As is clear from Table 1, in Examples having a high hemicellulose content, a satisfactory dyeing rate was exhibited together with satisfactory yarn quality, and the fiber texture was much more excellent.

Example 2 Kraft pulp was used as cellulose having a high degree of polymerization and rayon fiber was used as cellulose having a low degree of polymerization, and 15 parts by weight of a mixed cellulose obtained by mixing the former with the latter at a weight ratio of 20/80 was added to NMMO. : 73 parts by weight and 12 parts by weight of water were dissolved under reduced pressure at 110 ° C. The polymerization degree of each cellulose obtained by precipitating and coagulating with water from each single dope of the high polymerization degree cellulose and the low polymerization degree cellulose is 750 for the high polymerization degree cellulose, 300 for the low polymerization degree cellulose, and The polymerization degree was 390.

Using this spinning stock solution, dry-wet spinning was carried out under the conditions shown in Table 2, and the spinning speed was set to 200 m / min.
The discharged yarn was guided to a coagulation bath through an air gap of m. 0.50m at 10 ° C quench air with air gap
The dope filament was sprayed at right angles to the dope filament at a rate of / sec to perform cooling in the form of a thread. The filament obtained by coagulation in a coagulation bath at 10 ° C. at a concentration of 20% by weight was washed with water, dried and wound up, and the physical properties and the dyeing ratio were measured. The results are as shown in Table 2, and a regenerated cellulose fiber having high fiber properties and excellent dyeability was obtained.

[0041]

[Table 2]

[0042]

The present invention is constituted as described above, and by using a solvent containing NMMO as a solvent and adjusting the hemicellulose content to a specific range, excellent dyeability which has not been provided so far is obtained. In addition to providing regenerated cellulose fibers excellent in gloss, texture, etc., the problem of fibrillation is solved by using a high-polymerization degree cellulose and a low-polymerization degree cellulose in combination at a predetermined ratio as a raw material cellulose. In addition, a regenerated cellulose fiber excellent in texture and the like can be obtained.

Claims (4)

[Claims] 1. A regenerated cellulose fiber produced by using a spinning solution obtained by dissolving cellulose in a solvent containing N-methylmorpholine-N-oxide, wherein the content of hemicellulose in the regenerated cellulose fiber is 3 to 15% by weight. % Regenerated cellulose fiber having excellent dyeability. 2. An average degree of polymerization of cellulose contained in the fiber is 400 or less, and 5 to 5 of the cellulose.
The regenerated cellulose fiber according to claim 1, wherein 30% by weight has a degree of polymerization of 500 or more. 3. When producing a regenerated cellulose fiber using a spinning dope obtained by dissolving cellulose in a solvent containing N-methylmorpholine-N-oxide, the content of hemicellulose is adjusted to 3 to 15% by weight, and a dry-wet spinning method is used. A method for producing a regenerated cellulose fiber having excellent dyeability, characterized by spinning. 4. An average degree of polymerization of cellulose in the stock solution for spinning is set to 400 or less, 5 to 20% by weight of the cellulose is adjusted to 500 or more, and a gas flow is applied from a spinneret to a coagulation bath. The method according to claim 3, wherein the spun filament is cooled.