JP3829954B2 - Hollow cross-section regenerated cellulose fiber and process for producing the same - Google Patents

Description

表１からも明らかである様に、紡糸口金の導入角αが小さく、エアーギャップ長および冷却風条件として適切な条件を採用した場合に限り、紡糸が可能で且つ優れた糸質と中空断面の再生セルロースを得ることができる。
実施例２
高重合度のセルロースとしてレーヨン用パルプを、また低重合度のセルロースとしてレーヨン繊維を使用し、前者対後者を２０／８０の重量比で配合した混合セルロース１５重量部を、ＮＭＭＯ：７３重量部と水：１２重量部の混合液に１１０℃で減圧溶解した。高重合度セルロースおよび低重合度セルロースの各単独ドープから水で沈殿凝固させて得た各セルロースの重合度は、高重合度セルロースで重合度７５０、低重合度セルロースで重合度３００であり、平均重合度は３６８であった。
この紡糸原液を使用し、表２に示す条件で乾湿式紡糸を行ない、口金形状Ａの紡糸口金を用い紡速５０ｍ／分とし、２００ｍｍのエアーギャップを介して吐出糸条を凝固浴に導びいた。エアーギャップで１０℃のクエンチ風を０．５０ｍ／秒の速度でドープフィラメントに直角に吹き付け糸状の冷却を行った。２０重量％の濃度で１０℃凝固浴で凝固させて得られたフィラメントを水洗・乾燥して巻き取って物性と中空率を測定した。結果は表２に併記する通りであり、繊維物性の高い中空断面の再生セルロース繊維が得られている。
【００３８】
【表２】

【００３９】
【発明の効果】
本発明は以上の様に構成されており、溶媒としてＮＭＭＯを含む溶媒を用いて、これまで提供されたことのない中空断面で光沢、風合い等に優れた再生セルロース繊維を提供すると共に、原料セルロースとして、高重合度のセルローと低重合度のセルロースを所定の比率で併用することによりフィブリル化の問題も解消し、強度的にもまた風合い等においても優れた性能の再生セルロース繊維が得られる。
【図面の簡単な説明】
【図１】紡糸ノズルの形状を示す説明図である。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hollow cellulose regenerated cellulose fiber obtained by using a spinning stock solution in which cellulose is dissolved in a solvent containing N-methylmorpholine-N-oxide (hereinafter abbreviated as NMMO), and a method for producing the same. The present invention relates to a technique for obtaining a high-quality hollow cross-section regenerated cellulose fiber having excellent texture and enhanced fibril resistance.
[0002]
[Prior art]
A method for producing a regenerated cellulose fiber 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 great drawback that the obtained regenerated cellulose fiber is likely to be fibrillated, which has been an obstacle to generalization. However, this method has been attracting attention again recently because it has little adverse effects on the environment and is economically efficient, and the properties of the resulting recycled fibers are also good to some extent.
[0003]
On the other hand, improvement research has also been made on the above-mentioned problem of fibrillation, and several patent applications have been filed as seen in, for example, JP-A-8-501356, JP-A-7-508320, and JP-A-8-49167. In reality, it has not yet reached a satisfactory effect on a practical scale.
[0004]
In addition, when the regenerated cellulose fiber obtained using the above solvent is applied to the clothing field, etc., it is effective to make the cross section hollow in order to enhance the gloss and texture of the fiber itself or woven / knitted fabric. Although it is conceivable, no regenerated cellulose fiber having a hollow cross-sectional shape using an NMMO-containing solvent has been studied at present.
[0005]
[Problems to be solved by the invention]
The present invention has been made paying attention to the situation as described above. The purpose of the present invention is to utilize the characteristics of the method for producing regenerated cellulose fiber using the NMMO-containing solvent described above, and to maintain the maintenance characteristics thereof in the cross section. While further improving by hollowing out the shape, eliminating the problem of fibrillation pointed out as its disadvantage, providing regenerated cellulose fibers excellent in appearance such as clothing and excellent physical properties and texture, An attempt is made to establish a production method capable of stably producing such fibers.
[0006]
[Means for Solving the Problems]
The hollow cross-section regenerated cellulose fiber of the present invention that has solved the above-mentioned problems is a regenerated cellulose fiber produced using a spinning stock solution in which cellulose is dissolved in a solvent containing NMMO, and its cross section is hollow. However, its characteristics exist.
[0007]
Among these regenerated cellulose fibers, those having an average degree of polymerization of 400 or less in the fibers and 5 to 30% by weight of the cellulose having a degree of polymerization of 500 or more have excellent physical properties and texture. In addition to having the above-mentioned appearance characteristics, it is very excellent in fibril resistance and can be widely used for clothing.
[0008]
Further, the production method of the present invention is a method for producing a hollow cross-section regenerated cellulose fiber having the above-mentioned characteristics. When producing a regenerated cellulose fiber using a spinning stock solution in which cellulose is dissolved in a solvent containing NMMO, a C-shaped cross section is produced. There is a gist of producing a regenerated cellulose fiber having a hollow cross section by spinning by a dry and wet spinning method using the above spinneret. When carrying out this method, the average degree of polymerization of the cellulose in the spinning dope is suppressed to 400 or less, and if 5 to 30% by weight of the cellulose is adjusted to a degree of polymerization of 500 or more, the hollow ratio can be adjusted. It is preferable because the fibril resistance of the resulting fibers can be increased.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
The present inventors have advanced improvement studies from various angles in order to prevent the fibrillation pointed out in the regenerated cellulose fiber using a solvent containing NMMO, particularly the drawbacks of the prior art as described above. As a result, when producing a regenerated cellulose fiber using the above-mentioned solvent, using a spinning stock solution that causes a pseudo liquid crystal phenomenon in the spinning process, the obtained regenerated cellulose fiber is extremely less fibrillated. I found new facts that no one had ever recognized.
[0010]
In addition, using the spinning solution that produces the above-mentioned pseudo-liquid crystal phenomenon and dry-wet spinning using a spinneret with a C-shaped cross-section, the cross-sectional shape is hollow, and extremely excellent reproduction such as gloss and texture. I knew that cellulose fibers could be easily obtained.
[0011]
As a result of further research, the degree of polymerization of cellulose dissolved in the spinning stock solution is extremely important in order to produce the above-mentioned pseudo liquid crystal formation in the spinning process, and the average degree of polymerization of the cellulose is specified. In addition, it is sufficient to use a cellulose containing a high degree of polymerization and a low degree of cellulose in a specific ratio. When spinning using such a mixed cellulose solution as a spinning dope, fibrillation is extremely low. In addition, it was found that a high-quality regenerated cellulose fiber having a hollow cross section 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 the flow field and elongation field during spinning.
[0012]
In addition, as for the well-known regenerated cellulose fiber obtained using an NMMO containing solvent, the cross-sectional shape is a substantially circular hollow shape, and the thing of a hollow cross section is not known. Therefore, the hollow regenerated cellulose fiber of the present invention is very excellent in gloss and texture as a regenerated cellulose fiber itself and a woven or knitted fabric using the regenerated cellulose fiber as compared with a conventional regenerated cellulose having a substantially circular cross section. Therefore, it should be recognized as a new invention that can be clearly distinguished from conventional regenerated cellulose fibers.
[0013]
The hollow cross-section regenerated cellulose fiber having the above-described characteristics is obtained by using a solvent containing NMMO, using a spinning stock solution in which cellulose is dissolved, and dry and wet spinning using a spinneret having a C-shaped cross section. However, if the average degree of polymerization of cellulose dissolved in the spinning stock solution and the content ratio of cellulose with a high degree of polymerization are adjusted appropriately, a pseudo-liquid crystal phenomenon occurs in the spinning process, and the fibril resistance is very good. Regenerated cellulose fibers can be obtained.
[0014]
That is, in producing the regenerated cellulose fiber, the average degree of polymerization of cellulose dissolved in the spinning dope is set to 400 or less, and the content ratio of high polymerization degree cellulose having a degree of polymerization of 500 or more in the cellulose is 5 to 5. It is good to keep in the range of 30% by weight. When cellulose mixtures having different degrees of polymerization are used in this way, the cellulose component having a high degree of polymerization forms a structure mainly composed of extended chains by phase separation in the spinning process. The gaps are filled with cellulose having a low polymerization degree, and the resulting regenerated cellulose fibers form a composite structure, which is thought to suppress fibrillation.
[0015]
In other words, high-polymerized cellulose is the main cause of the pseudo-liquid crystallizing phenomenon and converges in the longitudinal direction to bear mechanical properties, while low-polymerized cellulose fills the gaps and enhances the required properties as clothing such as texture. These additive and synergistic effects provide a degree of deformation according to the shape of the spinneret, and give excellent strength characteristics and texture, and the fiber structure combined in a composite form makes the fibrils. It is possible to suppress the conversion as much as possible.
[0016]
In order to ensure such a composite structure and perform the spinning operation smoothly, it is better to keep the average degree of polymerization of cellulose dissolved in the spinning dope to 400 or less, and to ensure a pseudo-liquid crystal phenomenon in the spinning process. In order to secure sufficient mechanical properties in the longitudinal direction as the regenerated cellulose fiber obtained, the content ratio of the high polymerization degree cellulose having a polymerization degree of 500 or more in the cellulose should be 5% by weight or more. It becomes extremely effective. That is, when the content of the highly polymerized cellulose is less than 5% by weight, the above pseudo liquid crystal phenomenon does not easily occur in the spinning process, and not only the effect of preventing fibrillation by phase separation becomes insufficient, but also in the longitudinal direction. On the other hand, when the content ratio of the high polymerization degree cellulose having a polymerization degree of 500 or more exceeds 30% by weight, phase separation does not occur even if a pseudo liquid crystal phenomenon occurs in the spinning process, and the present invention. This makes it difficult not only to obtain a regenerated cellulose having a hollow cross section as intended, but also to prevent the 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 5 to 25% by weight, and more preferably 5 to 20% by weight.
[0017]
In the present invention, as described above, the ratio of low-polymerized cellulose is large, and the strength of the regenerated cellulose fiber tends to be slightly lower. However, in the clothing application, which is the main application of the present invention, As described above, the fiber strength at such a high level is not required, but rather the texture, fibril resistance, etc. are emphasized, so that lack of strength does not become a problem in practical use.
[0018]
The type of the high-polymerization cellulose used in the present invention is not particularly limited as long as the polymerization degree is 500 or more when used as a spinning dope, but the most common is a polymerization degree of 750 or more using wood pulp as a raw material. Of cellulose. However, as long as it satisfies the above requirements for the degree of polymerization, it is of course possible to use linter or cotton fiber. On the other hand, as the cellulose having a low polymerization degree, a recovered product of rayon fiber or the like is preferably used, but in addition, cellulose obtained from recovered products such as used paper or recovered used cotton can be used. These raw material celluloses are used after being wetted with ethanol or the like, pulverized or cut, and dried.
[0019]
In preparing the spinning dope, the cellulose has an average polymerization degree of 400 or less and a high polymerization degree cellulose content ratio of 500 or more is 5 to 30% by weight, more preferably 5 to 25% by weight. Further, the blending ratio of the high-polymerized cellulose and the low-polymerized cellulose may be adjusted so that it is more preferably in the range of 5 to 20% by weight.
[0020]
As the solvent used for the preparation of the spinning dope, a solvent containing NMMO is used. Preferred is a mixed solvent of NMMO and water, and particularly preferred is a NMMO / water mixing ratio of 90/10 to 40 /. A 90 weight ratio mixture.
[0021]
Then, a spinning dope is prepared by adding to these solvents so that the concentration of cellulose is preferably 15 to 25% by weight and dissolving it with a shear mixer or the like at a temperature of usually about 80 to 135 ° C. If the cellulose concentration in the spinning dope is too low, pseudo-liquid crystal spinning will not occur, and conversely if it is too high, the viscosity will be too high and spinning will be difficult, so the cellulose concentration in the spinning dope will be 15-25% by weight as described above. More preferably, it is desirable to prepare it in the range of 15 to 20% by weight.
[0022]
Since the raw material cellulose slightly lowers the degree of polymerization in the dissolving step, the degree of polymerization of the cellulose specified in the present invention is measured in the state after passing through the dissolving step, and the average degree of polymerization and the high degree of polymerization are measured. What is necessary is just to prepare the compounding quantity of the high polymerization degree cellulose used as a melt | dissolution raw material, and a low polymerization degree cellulose so that the content ratio of may satisfy | fill the above-mentioned requirements. At this time, it is preferable to add a stabilizer such as hydrogen peroxide, oxalic acid or a salt thereof, gallic acid, methyldigallic acid, glycoside, etc., in order to suppress degradation of the degree of polymerization of cellulose and decomposition of NMMO during dissolution. Recommended.
[0023]
A solution obtained by dissolving a cellulose raw material in a mixed solvent of NMMO and water has a relatively low viscosity and a high-concentration solution can be easily obtained, and its viscosity is also suitable for wet spinning. 51, 423 (1995).
[0024]
The solution having a high viscosity (zero shear viscosity at the melting temperature of about 5,000 poise or more) thus obtained is defoamed with a thin film evaporator, filtered, and then supplied to the spinning section. The high-viscosity spinning dope is sent to the spinning head, measured by a gear pump, and supplied to the spin pack. The spinning temperature is preferably in the range of 90 to 135 ° C. If the viscosity is lower than 90 ° C, spinning becomes difficult because the dope viscosity is too high, and if the temperature exceeds 135 ° C, the polymerization degree decreases due to decomposition of cellulose. The physical properties of the recycled fiber, especially the tensile strength, become poor.
[0025]
For the orifice used for spinning, it is effective to lengthen the L / D in order to increase the stability of the dope. However, since this causes a problem that the spinning back pressure becomes high, a tapered shape with a small introduction angle is preferable. It is desirable to suppress the generation of turbulence by using an orifice.
[0026]
At this time, in order to obtain a regenerated cellulose fiber having a hollow cross-sectional shape, for example, a C-shaped cross-sectional base as shown in FIGS. 1A to 1B is used as the spinneret. If a spinneret is used, the spinnability of the spinning dope will deteriorate, so it will be difficult to obtain a sufficient spinning draw ratio in the air gap from when the spinneret exits the spinneret until it enters the coagulation liquid. Even when a spinning stock solution using cellulose having a degree of polymerization as described above is used, the pseudo-liquid crystal phenomenon does not easily occur, and the effect of improving the hollow ratio and improving the fibril resistance is hardly exhibited.
[0027]
Therefore, as a result of continuing investigations on means capable of ensuring a sufficient spinning draw ratio even when using a C-shaped cross-section die as described above, for example, as shown in FIG. If the taper angle α of the part is made sufficiently small, turbulent flow generated in the orifice can be suppressed, and a sufficient stretching ratio can be secured even if the tip shape of the die is C-shaped, thereby causing a pseudo liquid crystal phenomenon. Thus, it was confirmed that the hollow cross-section was achieved and the fibril resistance was also efficiently increased. In order to obtain such an effect, it is desirable that the taper angle α of the introduction portion is preferably 45 degrees or less, more preferably 35 degrees or less, but it is difficult to make the taper angle α too small in machining. In addition, turbulent flow tends to occur at the entrance to the introduction portion, and on the contrary, there is a tendency to inhibit the spinnability. A more preferable taper angle is 15 to 30 degrees in consideration of the stringiness and workability in a comprehensive manner.
[0028]
The dope discharged from the base is stretched by a so-called air gap (a section until the dope discharged from the discharge part enters the coagulating liquid). However, when the tapered orifice as described above is used, a sufficient spinning draft is given. As a result, the pseudo-liquid crystal phenomenon is surely expressed, a predetermined hollowness is given, and the fibril resistance is also improved.
[0029]
Therefore, when practicing the present invention, in order to reduce the solution viscosity of a high-viscosity spinning stock solution, spinning is performed at a high temperature, and solidification is performed at a temperature lower than the spinning temperature. For example, this is described in JP-A-8-500863. As shown, it is necessary to adopt a dry and wet spinning method in which an air gap is provided until the discharge dope discharged from the spinning nozzle enters the coagulation bath. That is, when such a dry / wet prevention method is employed in carrying out the present invention, the high-polymerized cellulose in the high-concentration solution containing the high-polymerized cellulose and the low-polymerized cellulose as described above is converted into the air gap portion. In the flow field or elongation field formed in this, phase transition and phase separation are caused, and a pseudo liquid crystal transition phenomenon is caused in this part, so that high-polymerized cellulose forms a fiber skeleton, and regenerated cellulose fibers having a hollow cross section are easily obtained. In addition, the obtained regenerated cellulose exhibits sufficient strength even if it contains a large amount of cellulose having a low polymerization degree. The spinning speed is not particularly limited, but is usually 100 m / min or more, preferably 150 m / min or more.
[0030]
If the air gap has only non-solidifying gas such as normal air, the gap between the die and the coagulating liquid surface is set to 5 so that a large deformation speed can be obtained while suppressing molecular relaxation. What is necessary is just to set to about ~ 50 mm. Alternatively, when a method of positively cooling the discharged yarn using a quench chamber or the like is adopted, molecular relaxation does not occur, so the air gap may be long, and this is preferable in particular when spinning at high speed.
[0031]
As the coagulation bath, an aqueous solution of NMMO is preferably used, and it is desirable to use an aqueous solution having an NMMO concentration of 10 to 50% by weight. Therefore, if the NMMO concentration is less than 10% by weight, the recovery rate of the evaporated NMMO becomes low and it becomes uneconomical. Conversely, if the concentration exceeds 50% by weight, the filament becomes insufficiently solidified. . A more preferred NMMO concentration of the coagulation bath is in the range of 15-40% by weight. The preferable 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, the fiber performance is deteriorated due to insufficient coagulation, while the coagulation bath is set to -20 ° C. Even if the temperature is excessively cooled to a temperature lower than 1, the fiber performance is not improved further, so it is economically wasteful to cool further.
[0032]
The yarn that has passed through the coagulation bath is subsequently sent to the washing and drying process. At this time, collecting and processing the yarn using a collection device such as a net conveyor simplifies the equipment. It is extremely effective in the above. Furthermore, in order to further facilitate the collection by the net conveyor, it is also recommended as a preferable method to use a known double kickback roll or aspirator as disclosed in, for example, Japanese Patent Publication No. 47-29926. Moreover, when using the obtained regenerated cellulose fiber as a short fiber, it is also effective to provide a crimper in a process and to provide expansion / 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.
[0033]
The fiber bundle washed with water and dried using a net conveyor is wound up as a filament with a predetermined fineness by a winder when it is obtained as long fiber, and when it is obtained as short fiber, the bundled long fiber is immediately or separately cut with a cutter. You can get it. As the cutter, a rotary cutter or a guillotine cutter is generally used.
[0034]
【Example】
EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the following examples, but may be appropriately modified within a range that can meet the purpose described above and below. Of course, it is possible to implement them, and they are all included in the technical scope of the present invention. In addition, the measuring method of each performance employ | adopted by the following Example and the comparative example is as follows.
[0035]
[Measurement of polymerization degree of cellulose]
Measured by the copper ethylenediamine method described in “Polymer Material Test Method 2”, page 267, Kyoritsu Shuppan (1965), edited by Polymer Society of Japan.
[Measurement of hollowness]
The fiber section of 5 single fibers arbitrarily taken out from the fiber bundle was observed with an optical microscope, the area of the hollow part was divided by the area surrounding the outer periphery of the fiber from the obtained cross-sectional photograph, and the value obtained by multiplying by 100 The average value was defined as the hollow ratio.
[0036]
Example 1
A pulp for rayon was used as cellulose, and 15 parts by weight thereof was dissolved in a mixed solution of NMMO: 73 parts by weight and water: 12 parts by weight at 110 ° C. to obtain a spinning dope. Using this spinning stock solution, the spinnerets A (α = 30 degrees) and B (α) having different discharge angles with a C-shaped discharge portion (outer diameter 1500 μ, inner diameter 1400 μ, non-open portion width 500 μ). = 80 degrees), dry and wet spinning was performed under the conditions shown in Table 1, and the filaments obtained were washed with water, dried and wound, and the physical properties and the hollowness of the fibers were measured for each. The results shown in Table 1 Got.
[0037]
[Table 1]

As is apparent from Table 1, spinning is possible only when the introduction angle α of the spinneret is small and appropriate conditions are adopted as the air gap length and cooling air conditions. Regenerated cellulose can be obtained.
Example 2
15 parts by weight of mixed cellulose in which 15% by weight of the mixed cellulose containing 20% / 80 weight ratio of the former and the latter is used as NMMO: 73 parts by weight using rayon pulp as cellulose having a high degree of polymerization and rayon fiber as cellulose having a low degree of polymerization. Water: dissolved in a mixed solution of 12 parts by weight under reduced pressure at 110 ° C. The degree of polymerization 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 a polymerization degree of 750 for the high polymerization degree cellulose and a polymerization degree of 300 for the low polymerization degree cellulose. The degree of polymerization was 368.
Using this spinning dope, dry and wet spinning was performed under the conditions shown in Table 2, using a spinneret with a base A, spinning speed was 50 m / min, and the discharged yarn was introduced into the coagulation bath through a 200 mm air gap. It was. A 10 ° C. quench air was blown at right angles to the dope filament at a speed of 0.50 m / sec through an air gap to cool the yarn. Filaments obtained by coagulation in a 10 ° C. coagulation bath at a concentration of 20% by weight were washed with water, dried and wound up, and the physical properties and the hollow ratio were measured. The results are as shown in Table 2, and a regenerated cellulose fiber having a hollow cross section with high fiber properties is obtained.
[0038]
[Table 2]

[0039]
【The invention's effect】
The present invention is configured as described above, and using a solvent containing NMMO as a solvent, provides a regenerated cellulose fiber excellent in gloss, texture, etc. with a hollow cross section that has not been provided so far, and raw material cellulose As described above, by combining cellulose having a high degree of polymerization and cellulose having a low degree of polymerization at a predetermined ratio, the problem of fibrillation can be solved, and a regenerated cellulose fiber having excellent performance in terms of strength and texture can be obtained.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing the shape of a spinning nozzle.

Claims (3)

Regenerated cellulose fiber produced using a spinning stock solution in which cellulose is dissolved in a solvent containing N-methylmorpholine-N-oxide, and the average degree of polymerization of cellulose contained in the fiber is 400 or less, and A hollow cross-section regenerated cellulose fiber characterized in that 5 to 30% by weight of the cellulose has a degree of polymerization of 500 or more and the cross section is hollow. In producing a regenerated cellulose fiber using a spinning stock solution in which cellulose is dissolved in a solvent containing N-methylmorpholine-N-oxide , the average degree of polymerization is 400 or less and 5 to 30% by weight is polymerized in the spinning stock solution. A process for producing a hollow cross-section regenerated cellulose fiber, characterized in that cellulose having a degree of 500 or more is spun by a dry-wet spinning method using a spinneret having a C-shaped cross section. The process according to claim 2, wherein the spinning filament is cooled by a gas flow between the spinneret and the coagulation bath.

Images