JP4957141B2 - Cellulose fatty acid mixed ester hollow fiber - Google Patents

Description

  The present invention relates to a cellulose fatty acid mixed ester hollow fiber suitable for clothing having excellent lightness, heat retention and softness, with each single yarn constituting a multifilament continuously having a hollow portion in the fiber axis direction.

  Cellulose-based materials such as cellulose esters and cellulose ethers have recently attracted a great deal of attention as biomass materials that are produced in the most mass on the earth and as biodegradable materials in natural environments.

  Known cellulose-based filaments include regenerated cellulose fibers such as viscose and cupra, and cellulose acetate fibers such as cellulose diacetate and cellulose triacetate. None of these fibers can be fiberized by the melt spinning method because the composition has no thermoplasticity or the temperature at which thermoplasticization occurs is higher than the thermal decomposition temperature. Manufactured by a wet or dry spinning method. While these fibers are derived from cellulose, they have very good properties as clothing fibers, such as good gloss and moisture absorption and release, while environmental spinning because they are solution spinning using harmful organic solvents. Concerned.

  For this reason, as a fiberization by the melt spinning method, a technique has been proposed in which a large amount of a plasticizer is added to a cellulose ester resin to improve the thermal fluidity below the thermal decomposition temperature of the resin and perform melt spinning ( Patent Literatures 1 to 3).

  Cellulosic hollow fibers (membranes) obtained by these proposed methods have been practically used in reverse osmosis membranes and hemodialysis. However, although these hollow fibers have a very high hollow ratio, they have a large single yarn fineness (a single yarn has a large diameter) and thus cannot be used for clothing. Furthermore, the mechanical properties were very poor, and they did not have mechanical properties that could be practically used.

There has been no cellulosic hollow fiber having such a high hollow ratio but a small single yarn fineness and mechanical properties that can be practically used.
JP 54-42420 A JP 59-199807 A JP-A-60-5202

  An object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a cellulose fatty acid mixed ester hollow fiber having a thickness suitable for clothing and excellent in fiber mechanical properties.

  As a result of intensive studies to solve the above-mentioned problems, the inventors of the present invention are multifilaments composed of a thermoplastic composition mainly composed of a cellulose fatty acid mixed ester, and each single yarn constituting the multifilament is It succeeded in obtaining a cellulose fatty acid mixed ester hollow fiber having a hollow portion continuously in the fiber axis direction, having a specific high hollow ratio and excellent in mechanical properties, and completed the present invention. It was.

The present invention adopts the following configuration in order to achieve the above-described problems. That is,
[1] A cellulose-fatty acid mixed ester hollow fiber, which is a multifilament made of a thermoplastic composition containing a cellulose-fatty acid mixed ester as a main component and satisfies the following requirements (1) to (4) .
(1) Each single yarn constituting the multifilament has a hollow portion having a hollow ratio of 10 to 40 % continuously in the fiber axis direction.
(2) The tensile strength of the multifilament is 0.8 cN / dtex or more.
(3) The elongation of the multifilament is 15% or more.
(4) The diameter of the single yarn constituting the multifilament is 10 to 40 μm.

[2] The cellulose fatty acid mixed ester hollow fiber according to [1 ], wherein the cellulose fatty acid mixed ester is cellulose acetate propionate or cellulose acetate butyrate.

[3] A fiber structure comprising the cellulose fatty acid mixed ester hollow fiber according to any one of [1] or [2] at least in part.

[4] The fiber structure according to [3] , wherein the moisture absorption rate in a standard state at a temperature of 20 ° C. and a relative humidity of 65% is 2 to 8% by weight.

[5] The apparent density of the fiber structure is less than 1 g / cm ³ , and the fiber structure does not settle in water after being left in pure water for 24 hours [3] or The fiber structure according to [4] .

  According to the present invention, each single yarn constituting the multifilament has a hollow portion continuously in the fiber axis direction, and a cellulose fatty acid mixed ester hollow fiber excellent in mechanical properties can be obtained. Moreover, the cellulose-fatty-acid mixed ester hollow fiber of this invention can be used suitably for the use as which the lightweight property, heat retention, and softness are requested | required including the fiber for clothing.

  Hereinafter, the cellulose fatty acid mixed ester hollow fiber of the present invention will be described in detail.

  The cellulose fatty acid mixed ester in the present invention is one in which three hydroxyl groups present in the glucose unit of cellulose are blocked with two or more acyl groups. Specific examples of the cellulose fatty acid mixed ester are preferably cellulose acetate propionate in which an acetyl group and a propionyl group are bonded, and cellulose acetate butyrate in which an acetyl group and a butyryl group are bonded. In this case, the average substitution degree of the acetyl group and the acyl group (propionyl group or butyryl group) preferably satisfies the following formula. The average degree of substitution refers to the number of chemically bonded acyl groups among the three hydroxyl groups present per glucose unit of cellulose.

2.0 ≦ (average degree of substitution of acetyl group + average degree of substitution of acyl group) ≦ 3.0
1.5 ≦ (average degree of substitution of acetyl group) ≦ 2.5
0.5 ≦ (Average substitution degree of acyl group) ≦ 1.5
A cellulose fatty acid mixed ester satisfying the above formula is preferable because it has a high heat softening temperature, moderate hygroscopicity, and good dimensional stability when used as a fabric.

  The weight average molecular weight (Mw) of the cellulose fatty acid mixed ester is preferably 50,000 to 255,000. When Mw is less than 50,000, thermal decomposition during melt spinning becomes remarkable, and the mechanical properties (particularly tensile strength) of the fiber made of the cellulose fatty acid mixed ester composition obtained by melt spinning are practical levels. It is not preferable because it does not reach. If Mw exceeds 255,000, the melt viscosity becomes very high, and stable fiberization by melt spinning cannot be performed. From the viewpoint of good mechanical properties and stable melt spinnability, Mw is more preferably 60,000 to 20,000, and even more preferably 80,000 to 20,000,000. In addition, a weight average molecular weight (Mw) means the value computed by GPC measurement, and demonstrates in detail in an Example.

  The thermoplastic composition containing the cellulose fatty acid mixed ester as the main component in the present invention may contain a plasticizer, and the plasticizer is preferably a polyhydric alcohol compound. Specifically, polyalkylene glycols, glycerin compounds, caprolactone compounds, etc., which have good compatibility with cellulose fatty acid mixed esters and have a remarkable thermoplastic effect that can be melt-spun, especially polyalkylene glycols. Is preferred. Specific examples of the polyalkylene glycol include, but are not limited to, polyethylene glycol, polypropylene glycol, and polybutylene glycol having a weight average molecular weight of 200 to 4000, and these may be used alone or in combination. Can do.

  In the melt molding, the plasticizer content is preferably 5 to 25% by weight. By making the content of the plasticizer 5 to 25% by weight, the heat flow property of the cellulose fatty acid mixed ester is improved, so that production by a melt spinning method with high production efficiency is possible, and the fiber cross section is precisely and arbitrarily specified. It can be controlled and the resulting fiber properties are also good. The plasticizer content is more preferably 8 to 22% by weight, and most preferably 10 to 20% by weight.

  The thermoplastic composition mainly composed of a cellulose fatty acid mixed ester in the present invention preferably contains a phosphorus-based antioxidant, and particularly preferably a pentaerythritol-based compound. When a phosphorus-based antioxidant is contained, the thermal decomposition prevention effect is very remarkable even in the high spinning temperature range and the low discharge region, the deterioration of the mechanical properties of the fiber is suppressed, and the color tone of the resulting fiber Will be better. The compounding amount of the phosphorus-based antioxidant is preferably 0.005% by weight to 0.500% by weight with respect to the melt spinning composition.

  The cellulose fatty acid mixed ester hollow fiber of the present invention has a small single yarn diameter constituting a multifilament, a high hollow ratio, and excellent mechanical properties.

The hollow rate of the cellulose fatty acid mixed ester hollow fiber of the present invention is 10 to 40 %. When the hollowness is less than 10%, the effect of light weight intended by the present invention is insufficient, and the effect of heat retention is reduced. A higher hollow ratio is preferable from the viewpoint of weight reduction and heat retention. However, when the hollow ratio exceeds 40 %, fiber characteristics are deteriorated, fibrillation, and fiber crushing easily occur in higher processing steps. Become. For example, a force is applied from the lateral direction of the fiber due to the contact pressure with the rollers, the frictional force of the guides, or other external force, the fiber cross section is crushed, and the substantial hollowness is reduced.

In addition, the hollowness of the original yarn cannot be maintained even when it becomes a clothing product, and the cross section of the fiber is easily crushed during wearing. Furthermore, it becomes difficult to stably produce the hollow fiber in the melt spinning process .

  The hollow ratio as used in the present invention refers to photographing a cross section (transverse section) perpendicular to the fiber axis of the hollow fiber, measuring the total area (Sa) of the cross section and the area of the hollow part (Sb), The value calculated using the following formula. However, Sb means the sum total of the area of each hollow part, when it has a some hollow part.

Hollow ratio (%) = (Sb / Sa) × 100
The tensile strength of the cellulose fatty acid mixed ester hollow fiber in the present invention is 0.8 cN / dtex or more. If the tensile strength is 0.8 cN / dtex or more, it is preferable because it is easy to pass through high-order processing steps such as weaving and knitting, and the strength of the final product is not insufficient. From the viewpoint of good tensile strength characteristics, the higher the tensile strength, the more the practical range is widened and it can be developed for various uses, but at present, the upper limit is about 2.0 cN / dtex. The tensile strength is more preferably 0.9 cN / dtex or more, and further preferably 1.0 cN / dtex or more.

  The elongation of the cellulose fatty acid mixed ester hollow fiber in the present invention is 15% or more. When the elongation is 15% or more, fluff does not occur in the spinning process, and fluff and yarn breakage do not occur frequently in high-order processing processes such as weaving and knitting. Property is improved. The elongation is preferably 50% or less. When the elongation is 50% or less, the fiber will not be deformed if the stress is low, and a dyeing defect of the final product due to wetting marks during weaving will not occur. The elongation is more preferably 18% to 45%, further preferably 20 to 40%.

As for the diameter of the cellulose fatty acid mixed ester hollow fiber in the present invention, the single yarn diameter constituting the multifilament is 10 to 40 μm . By setting the single yarn diameter in this way, it can be applied to clothing fabrics and the like that require softness due to appropriate bending rigidity of the fiber structure. Incidentally single yarn diameter small enough softness increases smaller but, in terms of mechanical properties and fineness variation value (U%), it is preferable single fiber diameter is 10μm or more.

  The fineness variation value (U%) of the cellulose fatty acid mixed ester hollow fiber in the present invention is preferably 3.0% or less. The fineness variation value (U%) is an index of thickness unevenness in the fiber longitudinal direction, and can be obtained by a Worcester tester manufactured by Zerbegger Worcester. If the fineness variation value (U%) is 3.0% or less, it means that the uniformity in the longitudinal direction of the fiber is excellent. When processing into a woven or knitted fabric, no fluff or yarn breakage occurs, and dyeing is performed. Even if it is performed, defects such as strong dye spots and dyed streaks do not occur, and a high-quality woven or knitted fabric is obtained. The smaller the fineness variation value (U%), the better, but the current lower limit is 0.2%. The fineness variation value is more preferably 0.2 to 2.5%, further preferably 0.2 to 2.0%, and most preferably 0.2 to 1.5%. The measurement conditions of the fineness variation value (U%) will be described in detail in the examples.

  It does not specifically limit regarding the single yarn cross-sectional shape of the cellulose-fatty-acid mixed ester hollow fiber in this invention, For example, a normal circular cross section (FIG. 1 (a)-(c)), a triangle (FIG. 1 (d)), A polygonal cross section such as a quadrangle, a flat cross section, or the like can be employed. In addition, the hollow fiber cross-sectional shape of the outer side is circular, the inner shape is a triangle (FIG. 1 (b)), a hollow fiber having a different cross-sectional shape on the outer side and the inner side, such as a quadrangle (FIG. 1 (c)), It may be a hollow fiber having a plurality of hollow portions (FIGS. 1E and 1F).

  In the present invention, after melt-molding a thermoplastic composition mainly composed of cellulose fatty acid mixed ester, the plasticizer contained in the hollow fiber by chemical treatment using water such as warm water or hot water or an organic solvent, etc. The plasticizer content contained in the cellulose ester mixed ester hollow fiber in the final product is preferably 0 to 25% by weight. When the content of the plasticizer is within this range, it is preferable because the strength of the final product is not insufficient and the heat softening temperature is increased.

  The cellulose fatty acid mixed ester hollow fiber according to the present invention has a matting agent, deodorant, flame retardant, yarn friction reducing agent, anti-coloring agent, coloring pigment, dye, antistatic agent, and antibacterial agent as long as the physical properties are not impaired. In addition, inorganic fine particles and organic compounds can be contained as necessary as ultraviolet absorbers, infrared absorbers, crystal nucleating agents, fluorescent brighteners, and the like.

  When fiberizing a thermoplastic composition containing a cellulose fatty acid mixed ester as a main component by melt spinning, the spinning temperature is preferably 220 ° C to 280 ° C. By setting the spinning temperature to 220 ° C. or higher, the elongational viscosity of the yarn discharged from the spinneret is sufficiently reduced. Therefore, melt fracture (streamline turbulence occurs when the shear stress of the polymer is high when passing through the spinneret hole. In addition, short pitch periodic spots due to the phenomenon that the shape of the yarn discharged from the spinneret becomes irregular) do not appear, and excellent uniform fibers without thickness spots can be obtained. Furthermore, since the thinning deformation process of the yarn discharged from the spinneret becomes gentle, the fiber microstructure is developed and the fiber characteristics are improved. In addition, the spinning property is stable. In addition, by setting the spinning temperature to 280 ° C. or lower, it becomes possible to make the hollow ratio 10% or higher, and to suppress the thermal decomposition of the thermoplastic composition. Deterioration of quality due to coloring can be suppressed. The spinning temperature is more preferably 230 ° C to 270 ° C, and further preferably 240 ° C to 260 ° C.

  The cellulose fatty acid mixed ester hollow fiber of the present invention can use various spinnerets for producing hollow fibers. Specifically, there are a plurality of C-shaped slits (FIG. 2A) and a plurality of arc-shaped slit portions. (3-5 pieces) Spinneret (Figs. 2 (b) to (c)) arranged to form one discharge hole, and three slits arranged in a triangular shape to form one discharge hole It can be manufactured using a spinneret (FIGS. 2 (e) to (f)) or the like in which a plurality of T-shaped slit portions are arranged to form one discharge hole. it can.

  For example, in the case of the discharge holes shown in FIGS. 1A to 1C, the hollow ratio of the cellulose fatty acid mixed ester hollow fiber of the present invention can be arbitrarily set by changing the slit width and the discharge hole radius of the arc-shaped slit. However, the slit width is preferably 0.05 mm to 0.20 mm, and more preferably 0.07 mm to 0.18 mm.

  Further, the discharge hole radius is preferably 0.30 mm to 1.00 mm, and more preferably 0.35 mm to 0.90 mm.

  The distance between the slits is preferably 0.05 to 0.20 mm, and more preferably 0.07 to 0.18 mm.

  FIG. 3 is a view showing an embodiment of an apparatus used in the method for producing a cellulose fatty acid ester hollow fiber of the present invention. In FIG. 3, 1 is a spin block, 2 is a melt spinning pack, 3 is a spinneret, 4 is a cooling start point, 5 is a cooling device, 6 is a spun yarn, 7 is an oil supply device, and 8 is a first godet roller. , 9 is a second godet roller.

  The melted thermoplastic composition is extruded from the discharge hole of the spinneret 3 attached to the lower part of the melt spinning pack 2 attached to the spin block 1. The extruded spun yarn 6 is cooled to the room temperature by the cooling device 5 from the cooling start point 4, the finishing agent is applied by the oil supply device 7, and the first godet roller 8 and the second godet rotating at a predetermined speed. It is wound up as a package 10 by a winder through a dead roller 9.

  The position of the cooling start point 4 is preferably a distance from the lower surface of the spinneret 3 of 0 mm to 200 mm. When the position of the cooling start point is within this range, it is possible to obtain a hollow fiber having a high hollow ratio with excellent mechanical characteristics and uniformity without unevenness in the thickness of the yarn, with good spinning properties. The position of the cooling start point is more preferably 0 mm to 190 mm, and further preferably 0 to 180 mm. The cooling start point refers to the upper end of the cooling device (position indicated by reference numeral 4 in FIG. 3).

  The cooling air speed of the yarn discharged from the spinneret is preferably 0.01 m / second to 1.00 m / second. When the cooling air speed is in this range, the cooling of the single yarn constituting the yarn discharged from the spinneret becomes uniform, and the resulting fiber has excellent uniformity with no thickness variation. The cooling air speed is more preferably 0.10 m / second to 0.45 m / second, and further preferably 0.20 m / second to 0.50 m / second.

  The spinning speed is preferably 750 m / min to 3500 m / min. By setting the spinning speed to 750 m / min to 3500 m / min, a spinning stress that sufficiently promotes molecular orientation of the obtained fiber is applied, and a fiber having excellent fiber characteristics can be obtained. The spinning speed is more preferably 1000 m / min to 3000 m / min, and further preferably 1250 m / min to 2500 m / min.

  As described above, since the cellulose fatty acid mixed ester hollow fiber obtained in the present invention is excellent in lightness, heat retention, softness, hygroscopicity, and the like, in particular, fabrics such as taffeta, decyne, georgette, twill, Or it is suitable for making knitting such as tengu, smooth and tricot. Furthermore, it can be used not only for apparel use but also for various living materials as non-woven fabric use, medical use, sanitary material, and stuffing material.

  The fiber structure of the present invention is formed using at least a part of the cellulose fatty acid mixed ester hollow fiber of the present invention. In the fiber structure of the present invention, the fibers employed other than the cellulose fatty acid mixed ester hollow fiber are not particularly limited as long as they do not impair the spirit of the present invention, such as polyester fibers, polyamide fibers, acrylic fibers, polyolefin fibers, etc. Synthetic fibers, cotton, hemp, wool, silk, and other natural fibers, as well as chemical fibers such as cellulosic fibers obtained by solution spinning using rayon, acetate, triacetate, and N-methylmorpholine N oxide, and regenerated fibers are used as appropriate. be able to. From the viewpoint of the lightness of the fiber structure, the content of the cellulose fatty acid mixed ester hollow fiber relative to the total weight of the fiber structure may be 30% by weight or more even when the fiber structure is mixed with other fibers. Preferably, it is more preferably 50% by weight or more. Moreover, it is also possible to set it as the fiber structure using only the cellulose-fatty-acid mixed ester hollow fiber of this invention, In this case, it can be set as the fiber structure which expresses favorable lightweight property.

  Since the fiber structure of the present invention is formed using cellulose fatty acid mixed ester hollow fibers, it has moderate moisture absorption performance unlike, for example, hydrophobic propylopyrene hollow fibers. The fiber structure of the present invention preferably has a moisture absorption rate of 2 to 8% by weight in a standard state at a temperature of 20 ° C. and a relative humidity of 65% from the viewpoints of wearing comfort and antistatic properties. The moisture content in the standard state of the fiber structure of the present invention is more preferably 3% by weight or more, and most preferably 4% by weight or more from the viewpoint of wearing comfort and antistatic properties. Conversely, from the viewpoint of drying speed and wet strength retention, it is more preferably 7% by weight or less, and most preferably 6% by weight or less. The moisture absorption rate in the standard state of the fiber structure can be appropriately designed in light of the application in which the fiber structure is used.

The apparent density of the fiber structure of the present invention is less than 1 g / cm ³ , and it is preferable that the fiber structure does not settle in water after being left in pure water for 24 hours. In the case of the present invention, the apparent density refers to a value obtained by dividing the total weight (g) of the fibers constituting the fiber structure by the volume (cm ³ ) of the same fibers. Here, the fiber volume means an outer volume including a hollow in the case of a fiber having a hollow. If the apparent density is low, the lower the density, the better the light weight. Therefore, specifically, it is more preferably less than 0.9 g / cm ³ , and most preferably 0.8 g / cm ³ or less. When the apparent density is less than 1 g / cm ³ , it means that it is lighter than water at 4 ° C., and when it is actually left in water, it does not settle, that is, at least the fiber structure. A part of the water surface is shown. In the present invention, pure water refers to a material in which the density of impurities is reduced to substantially 1.0 by reducing the concentration of impurities in water by using known means such as an ion exchange resin or a reverse osmosis membrane.

The fiber structure of the present invention has a good moisture absorption property of 2 to 8% by weight in a standard state at a temperature of 20 ° C. and a relative humidity of 65%, and has an apparent density of less than 1 g / cm ^3. It is possible to appropriately employ the lightness that does not settle in water even after being left in pure water for 24 hours. Since it is excellent not only in light weight but also in hygroscopicity, it can be suitably used not only for general clothing such as outer and formal wear, but also in fields where light weight is particularly preferred, such as elderly care clothing.

  Hereinafter, the present invention will be described in more detail with reference to examples. In addition, each characteristic value in an Example is calculated | required with the following method. The present invention is not limited to these examples.

A. Average substitution degree of cellulose fatty acid mixed ester The calculation method of the average substitution degree of cellulose fatty acid mixed ester in which acetyl group and acyl group are bonded to cellulose is as follows.

  0.9 g of cellulose fatty acid mixed ester dried at 80 ° C. for 8 hours was weighed and dissolved by adding 35 ml of acetone and 15 ml of dimethyl sulfoxide, and further 50 ml of acetone was added. While stirring, 30 ml of 0.5N sodium hydroxide aqueous solution was added and saponified for 2 hours. After adding 50 ml of hot water and washing the side of the flask, it was titrated with 0.5N sulfuric acid using phenolphthalein as an indicator. Separately, a blank test was performed in the same manner as the sample. The supernatant of the solution after titration was diluted 100 times, and the composition of the organic acid was measured using an ion chromatograph. From the measurement result and the acid composition analysis result by ion chromatography, the substitution degree was calculated by the following formula.

TA = (B−A) × F / (1000 × W)
DSace = (162.14 × TA) / [{1− (Mwase− (16.00 + 1.01)) × TA} + {1− (Mwacy− (16.00 + 1.01)) × TA} × (Acy / Ace)}]
DSacy = DSace × (Acy / Ace)
TA: Total organic acid amount (ml)
A: Sample titration (ml)
B: Blank test titration (ml)
F: titer of sulfuric acid W: sample weight (g)
DSace: Average substitution degree of acetyl group DSacy: Average substitution degree of acyl group Mwash: Molecular weight of acetic acid Mwacy: Molecular weight of other organic acids Acy / Ace: Molar ratio of acetic acid (Ace) to other organic acids (Acy) 162 .14: Molecular weight of cellulose repeating unit 16.00: Atomic weight of oxygen 1.01: Atomic weight of hydrogen Weight average molecular weight (Mw) measurement by GPC It was completely dissolved in tetrahydrofuran so that the concentration of the cellulose fatty acid mixed ester was 0.15% by weight, and used as a sample for GPC measurement. Using this sample, GPC measurement was performed with Waters 2690 under the following conditions, and the weight average molecular weight (Mw) was determined in terms of polystyrene.

Column: Two Tosoh TSK gel GMHHR-H connected Detector: Waters2410 Differential refractometer RI
Moving bed solvent: Tetrahydrofuran Flow rate: 1.0 ml / min Injection volume: 200 μl
C. Hollow ratio A cross section (transverse section) in a direction perpendicular to the fiber axis of the hollow fiber was photographed, and the total area Sa of the cross section and the area Sb of the hollow portion were measured and calculated using the following formula. However, Sb becomes the sum total of the area of each hollow part, when a hollow fiber has a some hollow part.

    The hollowness was calculated using 10 single yarns constituting the multifilament, and was taken as the average value.

Hollow ratio (%) = (Sb / Sa) × 100
D. Tensile strength and elongation Under an environment of temperature 20 ° C. and humidity 65%, Shimadzu Autograph AG-50NISMS type was used and a tensile test was performed under the conditions of a sample length of 20 cm and a tensile speed of 20 cm / min. The value obtained by dividing the stress (cN) at the indicated point by the fineness (dtex) was taken as the tensile strength (cN / dtex). The elongation at that time was defined as elongation (%). The number of measurements was 5 times, and the average values were taken as tensile strength and elongation.

E. Single yarn diameter A cross section (cross section) perpendicular to the fiber axis of the hollow fiber was photographed to calculate the single yarn diameter. The diameter of the single yarn was calculated using 10 single yarns constituting the multifilament, and the average value was used.

F. Fineness fluctuation value (U% normal)
The U% measurement was obtained by measuring under the following conditions using a Worcester tester 4-CX manufactured by Zerbegger Worcester.

Measurement speed: 200 m / min Measurement time: 2.5 minutes Measurement fiber length: 500 m
Twist: S twist, 12000 / min. The number of measurements was 5, and the average value was U%.

G. Evaluation of lightness and softness Using two types of hollow yarn and solid yarn having the same yarn diameter as the hollow fiber (hollow rate 0%), the lightness and softness were evaluated as follows. First, a hollow knitted fabric and solid yarn were used to create a 5m long tubular knitted fabric with a 3 inch half diameter and 27 gauge circular knitting machine (model NCR-BL manufactured by Eikoku Sangyo Co., Ltd.). The sensory evaluation was carried out with the following criteria.
(1) Lightweight feeling: Whether the weight difference between the two tubular knitted fabrics was clearly felt when holding a hollow knitted fabric and a solid knitted fabric.
(2) Soft feeling: When grasping a hollow fiber tubular knitted fabric, did you feel that it was a soft touch with no coarse feeling, or did you feel that it was a hard touch with a feeling of coarseness remaining?
(3) Evaluation of lightness and soft feeling ◎: Nine or more people are judged to be significantly different (lightness or softness is excellent) ○: 7 to 8 people are significantly different (lightness or softness is excellent) △: Determined that 5 to 6 people are significantly different (lightness or softness is excellent) ×: 4 or less people are significantly different (lightness or softness is excellent) H. Moisture absorption rate in a standard state at a temperature of 20 ° C. and a relative humidity of 65% About 1 g of a fiber structure sample was prepared, and its weight when dry (W ₀ ) was measured. The sample was allowed to stand for 24 hours in a thermo-hygrostat (LH-20-11M manufactured by Nagano Kagaku Kikai Co., Ltd.) conditioned at 20 ° C. × 65% RH, and the weight of the sample in equilibrium (W ₂₀ ) Was measured. Thereafter, the moisture absorption rate in a standard state at a temperature of 20 ° C. and a relative humidity of 65% was determined by the following formula.

Moisture absorption _{(wt%) = {(W 20- W} o) / W 0} × 100
I. Floatability in pure water Pure water was prepared using pure port PP-101 manufactured by Shibata Kagaku Co., Ltd. using tap water as a raw material. The prepared pure water was put into a 10-L beaker, and the fiber structure used as a sample was once immersed in water so that the entire fiber structure was submerged in water, and then allowed to stand for 24 hours. Observation was made after 24 hours to determine whether a part of the fiber structure was on the water surface or whether the entire fiber structure was submerged in water.

Synthesis example 1
To 100 parts by weight of cellulose (cotton linter), 240 parts by weight of acetic acid and 67 parts by weight of propionic acid were added and mixed at 50 ° C. for 30 minutes. After the mixture was cooled to room temperature, 172 parts by weight of acetic anhydride cooled in an ice bath and 168 parts by weight of propionic anhydride were added as an esterifying agent, and 4 parts by weight of sulfuric acid was added as an esterification catalyst, followed by stirring for 150 minutes. An esterification reaction was performed. In the esterification reaction, when it exceeded 40 ° C., it was cooled in a water bath. After the reaction, a mixed solution of 100 parts by weight of acetic acid and 33 parts by weight of water was added as a reaction terminator over 20 minutes to hydrolyze excess anhydride. Thereafter, 333 parts by weight of acetic acid and 100 parts by weight of water were added, and the mixture was heated and stirred at 80 ° C. for 1 hour. After completion of the reaction, an aqueous solution containing 6 parts by weight of sodium carbonate was added, and the precipitated cellulose acetate propionate was filtered off, subsequently washed with water, and dried at 60 ° C. for 4 hours. The average substitution degree of the acetyl group and propionyl group of the obtained cellulose acetate propionate was 1.9 and 0.7, respectively, and the weight average molecular weight (Mw) was 178,000.

Example 1
84% by weight of cellulose acetate propionate prepared in Synthesis Example 1, 15.9% by weight of polyethylene glycol (PEG 600) having an average molecular weight of 600, and bis (2,6-di-t-butyl-4-l) as a phosphorus-based antioxidant Methylphenyl) pentaerythritol diphosphite (0.1% by weight) was kneaded at 240 ° C. using a biaxial extruder and cut to about 5 mm to obtain cellulose fatty acid mixed ester composition pellets (Mw 16,000,000).

  The pellets were vacuum dried at 80 ° C. for 8 hours, melted at a melter temperature of 260 ° C., introduced into a melt spinning pack having a spinning temperature of 270 ° C., and discharged under a condition of a discharge rate of 15.0 g / min. A base hole (C-shaped slit having a discharge hole radius of 0.50 mm and a slit width of 0.10 mm) shown in (a) was spun from a base having 36 holes. This spun yarn is cooled by cooling air at a temperature of 150 mm below the spinneret surface (cooling start point) with cooling air at 25 ° C. and a wind speed of 0.3 m / sec. With a winder rotating at a speed at which the winding tension is 0.09 cN / dtex via a second godet roller rotating at the same speed as the first godet roller. Winded up.

The resulting fiber (100 dtex-36 filament) has a hollowness of 27%, a strength of 1.28 cN / dtex, an elongation of 22.9%, a single yarn diameter of 19.7 μm, The sensory evaluation results of the knitted fabric were excellent in both lightness and softness. (See Table 1)
Example 2
80% by weight of cellulose acetate propionate prepared in Synthesis Example 1, 19.9% by weight of polyethylene glycol (PEG 600) having an average molecular weight of 600, and bis (2,6-di-t-butyl-4-l) as a phosphorus-based antioxidant Methylphenyl) pentaerythritol diphosphite (0.1% by weight) was kneaded at 210 ° C. using a biaxial extruder and cut to about 5 mm to obtain cellulose fatty acid mixed ester composition pellets (Mw 171,000).

  The pellets were vacuum dried at 80 ° C. for 8 hours, melted at a melter temperature of 250 ° C., introduced into a melt spinning pack having a spinning temperature of 250 ° C., and discharged under a condition of a discharge rate of 33.0 g / min. A base hole (a three-part slit comprising a slit with a discharge hole radius of 0.60 mm, a pitch between slits of 0.10 mm, and a slit width of 0.07 mm) shown in (b) was spun from a base having 48 holes. The spun yarn was cooled by cooling air at 25 ° C. and a wind speed of 0.40 m / sec from a distance of 100 mm below the spinneret surface (cooling start point), and after being converged by applying an oil agent, 2000 m / min. With a winder rotating at a speed at which the winding tension is 0.09 cN / dtex via a second godet roller rotating at the same speed as the first godet roller. Winded up.

The obtained fiber (167 dtex-48 filament) has a hollow ratio of 33%, a strength of 1.09 cN / dtex, an elongation of 23.8%, and a single yarn diameter of 23.0 μm. The sensory evaluation results were excellent in both lightness and softness. (See Table 1)
Example 3
82% by weight of cellulose acetate propionate prepared in Synthesis Example 1, 17.9% by weight of polyethylene glycol (PEG 600) having an average molecular weight of 600, and bis (2,6-di-t-butyl-4-l) as a phosphorus-based antioxidant Methylphenyl) pentaerythritol diphosphite (0.1% by weight) was kneaded at 230 ° C. using a biaxial extruder and cut to about 5 mm to obtain cellulose fatty acid mixed ester composition pellets (Mw 166,000).

  The pellets were vacuum dried at 80 ° C. for 8 hours, melted at a melter temperature of 260 ° C., introduced into a melt spinning pack having a spinning temperature of 260 ° C., and discharged under a condition of a discharge rate of 18.0 g / min. Spinneret holes shown in (c) were spun from a die having 24 holes (a four-part slit comprising a slit having a discharge hole radius of 0.55 mm, a pitch between slits of 0.10 mm, and a slit width of 0.08 mm). The spun yarn is cooled from a distance of 140 mm below the spinneret surface (cooling start point) with cooling air at 25 ° C. and a wind speed of 0.30 m / sec. With a winder rotating at a speed at which the winding tension is 0.09 cN / dtex via a second godet roller rotating at the same speed as the first godet roller. Winded up.

The obtained fiber (100 dtex-24 filament) has a hollow ratio of 40%, a strength of 1.15 cN / dtex, an elongation of 26.0%, and a single yarn diameter of 26.6 μm. The sensory evaluation results were excellent in both lightness and softness. (See Table 1)
Example 4
Kneading 88% by weight of cellulose acetate butyrate (CAB381-20) manufactured by Eastman Chemical Co., Ltd. and 12% by weight of polyethylene glycol (PEG600) having an average molecular weight of 600 at 210 ° C. using a biaxial extruder, cutting to about 5 mm. Cellulose ester composition pellets (Mw 120,000) were obtained.

  This pellet was vacuum-dried at 80 ° C. for 8 hours, melted at a melter temperature of 245 ° C., introduced into a melt spinning pack having a spinning temperature of 245 ° C., and discharged under a condition of a discharge rate of 10.0 g / min. The die hole shown in (e) (a four-part slit comprising a T-shaped slit having a discharge hole radius of 0.62 mm and a slit width of 0.10 mm) was spun from a die having 36 holes. The spun yarn is cooled by cooling air at a temperature of 70 mm below the spinneret surface (cooling start point) with cooling air at 25 ° C. and a wind speed of 0.25 m / sec. In a winder rotating at a speed at which the winding tension is 0.09 cN / dtex via a second godet roller rotating at the same speed as the first godet roller. Winded up.

The obtained fiber (80 dtex-24 filament) has a hollowness of 20%, a strength of 1.13 cN / dtex, an elongation of 25.1%, and a single yarn diameter of 20.7 μm. The sensory evaluation results were excellent in both lightness and softness. (See Table 1)
Example 5
The fiber obtained in Example 2 was treated in warm water at 70 ° C. for 30 minutes to elute all the plasticizer (polyethylene glycol) contained in the fiber. The obtained fiber (133 dtex-48 filament) has a hollowness of 31%, a strength of 1.55 cN / dtex, an elongation of 16.8%, and a single yarn diameter of 20.2 μm. The sensory evaluation results were excellent in both lightness and softness. (See Table 1)
Further, when the moisture absorption rate of the tubular knitted fabric at a temperature of 20 ° C. and a relative humidity of 65% was measured, it was 4.2% by weight and was excellent in comfort. The apparent density of the tubular knitted fabric was 0.89, and when the buoyancy in pure water was evaluated, it was confirmed that the tubular knitting was located in the vicinity of the water surface and a part thereof was present on the water surface.

Example 6
The fiber obtained in Example 3 was treated in hot water at 90 ° C. for 20 minutes to elute all the plasticizer (polyethylene glycol) contained in the fiber. The obtained fiber (82 dtex-24 filament) has a hollowness of 39%, a strength of 1.62 cN / dtex, an elongation of 17.5%, and a single yarn diameter of 23.9 μm. The sensory evaluation results were excellent in both lightness and softness. (See Table 1)
Further, when the moisture absorption rate of the tubular knitted fabric at a temperature of 20 ° C. and a relative humidity of 65% was measured, it was 3.8% by weight and was excellent in comfort. The apparent density of the tubular knitted fabric was 0.78, and the buoyancy in pure water was evaluated. As a result, the tubular knitted fabric was located near the water surface, and it was confirmed that a part of the tubular knitted fabric was present on the water surface. .

Comparative Example 1
The pellets used in Example 1 were vacuum dried at 80 ° C. for 8 hours, melted at a melter temperature of 260 ° C., introduced into a melt spinning pack with a spinning temperature of 270 ° C., and discharged at a rate of 15 g / min. Spinners were spun from a die having 36 holes of 0.25 mmφ-0.625 mmL. The spun yarn is cooled by cooling air at a temperature of 150 mm below the spinneret surface (cooling start point) with cooling air at 25 ° C. and a wind speed of 0.30 m / sec. With a winder rotating at a speed at which the winding tension is 0.09 cN / dtex via a second godet roller rotating at the same speed as the first godet roller. Winded up.

The obtained fiber (solid yarn: 100 dtex-36 filament) has a strength of 1.36 cN / dtex, an elongation of 24.0%, and a single yarn diameter of 16.8 μm. From the result, it was very inferior to the lightweight feeling. (See Table 1)
This tubular knitted fabric was treated in hot water at 90 ° C. for 20 minutes to elute all the plasticizer (polyethylene glycol) contained in the fiber. The hygroscopicity of the tubular knitted fabric at a temperature of 20 ° C. and a relative humidity of 65% was 3.8% by weight, and the comfort was excellent. The apparent density of the tubular knitted fabric was 1.28, and when the buoyancy in pure water was evaluated, the tubular knitted fabric was completely submerged in water, and no buoyancy was exhibited.

Comparative Example 2
The pellets used in Example 2 were vacuum dried at 80 ° C. for 8 hours, melted at a melter temperature of 250 ° C., and introduced into a melt spinning pack having a spinning temperature of 250 ° C., and a discharge rate of 33.0 g / min. Spinning from a die having 48 holes as shown in FIG. 2B (a three-part slit comprising a discharge hole radius of 0.45 mm, a pitch between slits of 0.10 mm, and a slit width of 0.15 mm) as shown in FIG. did. The spun yarn was cooled from a distance of 70 mm below the spinneret surface (cooling start point) with cooling air at 25 ° C. and a wind speed of 0.40 m / sec. With a winder rotating at a speed at which the winding tension is 0.09 cN / dtex via a second godet roller rotating at the same speed as the first godet roller. Winded up.

The obtained fiber (167 dtex-48 filament) has a hollowness of 8%, a strength of 1.16 cN / dtex, an elongation of 27.8%, and a single yarn diameter of 19.6 μm. From the sensory evaluation results, it was very inferior in lightness. (See Table 1)
Comparative Example 3
The pellets used in Example 3 were vacuum dried at 80 ° C. for 8 hours, melted at a melter temperature of 260 ° C., introduced into a melt spinning pack having a spinning temperature of 260 ° C., and a discharge amount of 18.0 g / min. Spinning from a die having 24 holes as shown in FIG. 2C (a four-part slit comprising a slit having a discharge hole diameter of 1.25 mm, a pitch between slits of 0.10 mm, and a slit width of 0.08 mm) as shown in FIG. did. The spun yarn is cooled by a cooling air of 25 ° C. and a wind speed of 0.30 m / sec from a distance of 20 mm below the spinneret surface (cooling start point), and is converged by applying an oil agent to 1800 m / min. With a winder rotating at a speed at which the winding tension is 0.09 cN / dtex via a second godet roller rotating at the same speed as the first godet roller. Winded up.

The obtained fiber (100 dtex-24 filament) has a hollowness of 62%, a strength of 0.62 cN / dtex, an elongation of 14.6%, and a single yarn diameter of 33.3 μm. From the sensory evaluation results, the soft feeling was very inferior. (See Table 1)
Example 7
The pellets used in Example 3 were vacuum dried at 80 ° C. for 8 hours, melted at a melter temperature of 260 ° C., introduced into a melt spinning pack having a spinning temperature of 260 ° C., and a discharge amount of 45.0 g / min. Spinning from a die having 6 holes as shown in FIG. 2 (c) under the conditions (a four-part slit comprising a discharge hole radius of 1.50 mm, a pitch between slits of 0.13 mm, and a slit width of 0.08 mm). did. The spun yarn is cooled by cooling air at a temperature of 25 ° C. and a wind speed of 0.67 m / sec from a distance of 70 mm below the spinneret surface (cooling start point), and an oil agent is applied to converge the spun yarn. After that, a speed at which the take-up tension becomes 0.09 cN / dtex through a second godet roller that rotates at the same speed as the first godet roller is picked up by a first godet roller that rotates at 1500 m / min. It was wound up with a winder rotating at.

The obtained fiber (300 dtex-6 filament) has a hollowness of 48%, a strength of 0.82 cN / dtex, an elongation of 55.8%, and a single yarn diameter of 101.0 μm. From the sensory evaluation results, the softness was slightly inferior. (See Table 1)
Example 8
A taffeta woven fabric was prepared using a commercially available polyethylene terephthalate fiber (56T-24f-NS92 manufactured by Toray Industries, Inc.) as a warp and the cellulose fatty acid ester hollow fiber obtained in Example 3 as a weft. The obtained woven fabric was scoured at 80 ° C. in hot water for 20 minutes to elute all the polyethylene glycol contained in the cellulose fatty acid ester hollow fiber. The warp density of the scoured fabric was 40 / cm, the weft density was 50 / cm, the polyester fiber in the fiber structure was 35% by weight, and the cellulose fatty acid mixed ester hollow fiber was 65% by weight.

  When the moisture absorption rate of the obtained taffeta fabric in a standard state at a temperature of 20 ° C. and a relative humidity of 65% was measured, it was 2.4% by weight and was excellent in comfort. Moreover, the apparent density of the taffeta fabric was 0.97, and when the buoyancy in pure water was evaluated, it was confirmed that the taffeta fabric was located near the water surface, and a part thereof was present on the water surface. .

  The obtained fiber has a hollow portion in which each single yarn constituting the multifilament is continuous in the fiber axis direction, and is excellent in lightness, heat retention and softness, and is particularly suitably used for clothing fibers. be able to.

It is the figure which illustrated typically the fiber cross-sectional shape of the cellulose fatty acid mixed ester hollow fiber of this invention. It is the figure which illustrated typically the shape of the discharge hole at the time of manufacturing the cellulose fatty acid mixed ester hollow fiber of FIG. It is a figure which shows one embodiment of the melt spinning apparatus used for the manufacturing method of the cellulose fatty acid mixed ester hollow fiber of this invention.

Explanation of symbols

1: Spin block 2: Melt spinning pack 3: Spinneret 4: Cooling start point 5: Cooling device 6: Spinning yarn 7: Oil supply device 8: First godet roller 9: Second godet roller 10: Winding yarn

Claims (5)

A cellulose-fatty acid mixed ester hollow fiber, which is a multifilament composed of a thermoplastic composition containing a cellulose-fatty acid mixed ester as a main component and satisfies the following requirements (1) to (4) .
(1) Each single yarn constituting the multifilament has a hollow portion having a hollow ratio of 10 to 40 % continuously in the fiber axis direction.
(2) The tensile strength of the multifilament is 0.8 cN / dtex or more.
(3) The elongation of the multifilament is 15% or more.
(4) The diameter of the single yarn constituting the multifilament is 10 to 40 μm. The cellulose fatty acid mixed ester hollow fiber according to claim 1, wherein the cellulose fatty acid mixed ester is cellulose acetate propionate or cellulose acetate butyrate. Claim 1 or the fiber structure characterized by comprising using at least a portion of the cellulose fatty acid mixed ester hollow fiber according to any one of 2. The fiber structure according to claim 3 , wherein the moisture absorption rate in a standard state at a temperature of 20 ° C and a relative humidity of 65% is 2 to 8% by weight. Apparent density of the fiber structure is less than 1 g / cm ^3, even after standing for 24 hours the fiber structure in pure water, according to claim 3 or 4, characterized in that without precipitation in water Fiber structure.

Images