JP2004211278A - Cellulose fatty acid ester fiber and process for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cellulose fatty acid ester excellent in mechanical properties as a fiber and excellent in process passableness, in an effective producing method by a melt spinning without giving the impact on the environment. <P>SOLUTION: The cellulose fatty acid ester fiber comprises a composition comprising 80-98 wt.% of the cellulose fatty acid ester wherein at least a part of the acyl group in the cellulose fatty acid ester has 3 to 18 carbons and 2-20 wt.% of a polyhydric alcohol based plasticizer. The strength S (cN/dtex) and elongation E (%) of the fiber satisfy following formulas; 6≤S×E<SP>1/2</SP>≤10, 15≤E≤50. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to cellulose fatty acid ester fibers having good fiber properties and a method for producing the same.

  BACKGROUND ART Cellulose-based materials such as cellulose esters and cellulose ethers are attracting a great deal of attention in recent years as biomass materials produced on a large scale on the earth and as biodegradable materials in natural environments.

  Regarding the use of cellulose as a fiber, it has long been practiced to spin short fibers such as cotton and hemp produced in nature as they are. In order to obtain filament materials instead of short fibers, cellulose is dissolved in a special solvent system such as carbon disulfide, such as rayon, and spinning is performed by wet spinning, or cellulose is derivatized, such as cellulose acetate. Then, after dissolving in an organic solvent such as methylene chloride or acetone, there is no other method than spinning by a dry spinning method of spinning while evaporating the solvent. In these wet spinning or dry spinning methods, organic solvents such as carbon disulfide, acetone, and methylene chloride are highly likely to have a bad influence on the environment. It cannot be said that this is a simple thread-making method. Furthermore, since spinning is performed using a large amount of solvent, a large amount of energy is required for spinning and solvent recovery, and low spinning speed results in low productivity and high production cost. On the other hand, the melt spinning method has the advantages that the energy cost is low, the productivity is high, and various kinds of fibers can be spun.

  However, cellulose fatty acid esters represented by cellulose acetate have inferior thermal fluidity as compared with thermoplastic polymers such as polyester and polyamide, so that a large amount of a plasticizer must be added for melt spinning. Required. It is basically possible to add a large amount of a plasticizer to the cellulose fatty acid ester and melt-spin at a temperature not higher than the thermal decomposition temperature of the cellulose fatty acid ester, for example, a cellulose fatty acid ester for hemodialysis or an ultrafiltration membrane. Various proposals have been made for the purpose of obtaining fibers (for example, see Patent Documents 1 to 3).

Since the cellulose fatty acid ester fiber obtained by the above-mentioned method contains a large amount of a plasticizer of about 50% by weight in the composition, the mechanical properties of the obtained fiber were very poor. As an example of a cellulose fatty acid ester fiber obtained by a melt spinning method, Patent Document 4 discloses a description of fiberization of cellulose acetate by a melt spinning method. Here, the strength is 0.44 cN / dtex, the elongation is 15%, and only a very low fiber having a toughness (strength x elongation ^1/2 ) of 1.7 is obtained (for example, see Patent Document 4). .

Separately from the above, cellulose acetate and a plasticizer (caprolactone tetraol, polyethylene succinate) are used for the purpose of reducing the breaking rate during melt spinning and obtaining cellulose ester fibers having high fiber strength. Etc.) to obtain fibers by a melt spinning method. However, even though it has high fiber strength, only fibers having a low strength and a low toughness of at most 1.02 g / D (= 0.90 cN / dtex) are obtained (for example, see Patent Document 5).
Japanese Patent Publication No. 7-78288 (pages 1-2) JP-A-59-49806 (page 1) JP-A-54-42420 (page 1) JP-A-10-130957 (page 5) JP-A-10-317228 (pages 1-3, 5, 7)

  An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a cellulose fatty acid ester fiber having excellent mechanical properties and a method for producing the same.

In order to solve the above problems, the present invention employs the following configurations. That is,
(1) A composition comprising at least 80 to 98% by weight of a cellulose fatty acid ester in which at least a part of acyl groups of the cellulose fatty acid ester has 3 to 18 carbon atoms and 2 to 20% by weight of a polyhydric alcohol plasticizer. A cellulose fatty acid ester fiber, wherein the fiber has a strength S (cN / dtex) and an elongation E (%) satisfying the following formula.

6 ≦ SE ^1/2 ≦ 10
15 ≦ E ≦ 50
(2) A composition comprising at least 80 to 98% by weight of a cellulose fatty acid ester in which at least a part of the acyl group of the cellulose fatty acid ester has 3 to 18 carbon atoms and 2 to 20% by weight of a polyhydric alcohol plasticizer. The cellulose fatty acid ester fiber according to the above (1), wherein the fiber has a yield point stress of 0.5 to 1.5 cN / dtex. (3) At least the acyl group of the cellulose fatty acid ester The cellulose fatty acid ester fiber according to the above (1) or (2), wherein the cellulose fatty acid ester partially having 3 to 18 carbon atoms is cellulose acetate propionate.

  (4) When melt-spinning a composition comprising at least a cellulose ester having at least a part of an acyl group having 3 to 18 carbon atoms and a polyhydric alcohol-based plasticizer, the spinning temperature is set to 200 to 280 ° C. And a spinning speed of 700 to 2000 m / min and an atmosphere temperature under the die of 80 to 280 ° C.

  The fiber comprising the composition comprising at least the cellulose fatty acid ester of the present invention and a polyhydric alcohol-based plasticizer is a cellulose fatty acid ester fiber having excellent processability due to its high elongation characteristics and high yield point stress. The fibers can be used as clothing fibers, industrial fibers, nonwoven fabrics, and the like, and can be particularly preferably used as clothing fibers.

  Hereinafter, the cellulose fatty acid ester fiber will be described in detail.

  In the cellulose fatty acid ester of the present invention, at least a part of the acyl group has 3 to 18 carbon atoms. When the number of carbon atoms is 3 to 18, the compatibility with the polyhydric alcohol-based plasticizer is good, and the addition of a small amount of the polyhydric alcohol-based plasticizer results in a thermofluidity capable of melt spinning, which is preferable. Specific examples of the cellulose fatty acid ester in which at least a part of the acyl group has 3 to 18 carbon atoms include cellulose acetate propionate, cellulose propionate, cellulose acetate butyrate, cellulose butyrate, cellulose propionate butyrate, Cellulose acetate valerate, cellulose valerate, cellulose acetate laurate, cellulose laurate, cellulose acetate oleate, cellulose oleate and the like can be exemplified. Among them, cellulose has an acetyl group having 2 carbon atoms of an acyl group and 3 carbon atoms. The cellulose acetate propionate having a propionyl group bonded thereto has an appropriate hygroscopic property and is easy to produce. Therefore, as the cellulose fatty acid ester having at least a part of the acyl group having 3 to 18 carbon atoms, cellulose acetate propionate is preferable. In this case, the average degree of substitution of the acetyl group and the propionyl group preferably satisfies the following formula. The average degree of substitution refers to the number of acyl groups chemically bonded among the three hydroxyl groups present per glucose unit of cellulose.

2.0 ≦ (degree of substitution of acetyl group + degree of substitution of propionyl group) ≦ 3.0
0.1 ≦ (degree of substitution of acetyl group) ≦ 2.0
0.5 ≦ (degree of substitution of propionyl group) ≦ 2.9
Cellulose fatty acid esters satisfying the above formula are preferred from the viewpoint of compatibility with polyhydric alcohol plasticizers and good thermal fluidity.

  The weight average molecular weight (Mw) of the cellulose fatty acid ester in which at least a part of the acyl group has 3 to 18 carbon atoms is preferably 30,000 to 300,000. If the Mw is less than 30,000, the fiber properties of the cellulose fatty acid ester fibers are undesirably reduced. When Mw is larger than 300,000, the melt viscosity becomes extremely high, so that stable fiber formation by melt spinning cannot be performed. Mw is more preferably from 50000 to 270000, and most preferably from 80000 to 250,000. The weight average molecular weight (Mw) refers to a value calculated by GPC measurement, and will be described in detail in Examples.

  The content of the polyhydric alcohol plasticizer is 2 to 20% by weight. By setting the content of the polyhydric alcohol-based plasticizer to 2 to 20% by weight, the heat fluidity of the cellulose fatty acid ester is improved, so that the production by the melt spinning method with high production efficiency becomes possible, and the fiber cross section is thereby improved. Can be arbitrarily controlled, or a composite fiber can be obtained. Further, stretching and false twisting can be easily performed by utilizing good thermoplasticity.

  When the content of the polyhydric alcohol-based plasticizer is less than 2% by weight, the heat fluidity of the cellulose fatty acid ester is not good, so that melt fracture or poor spinning occurs at the time of melt spinning, and fiberization by the melt spinning method is difficult. turn into.

  When the content of the polyhydric alcohol plasticizer is more than 20% by weight, the heat fluidity of the cellulose fatty acid ester is improved, but the polyhydric alcohol plasticizer contained in the fiber obtained by spinning is stained on the fiber surface. It gives out and produces a slimy feeling due to it, and a high quality product cannot be obtained. Furthermore, thermal dimensional stability is deteriorated, and a problem due to shrinkage occurs in a dyeing step or a high-order processing step, which makes handling difficult. In the case of fabric, there is no beam (tension) or strain (waist). The content of the polyhydric alcohol ester-based plasticizer is more preferably 5 to 20% by weight, and most preferably 8 to 20% by weight.

  Polyhydric alcohol plasticizers that can be used specifically in the present invention have good compatibility with cellulose fatty acid esters, and glycerin ester compounds such as glycerin esters and diglycerin esters that have a remarkable thermoplastic effect, and Examples thereof include polyalkylene glycols such as polyethylene glycol and polypropylene glycol, and compounds in which an acyl group is bonded to a hydroxyl group of the polyalkylene glycol.

  Specific examples of glycerin esters include glycerin diacetate stearate, glycerin diacetate palmitate, glycerin diacetate mysylate, glycerin diacetate traurate, glycerin diacetate caprate, glycerin diacetate nonanoate, glycerin diacetate octanoate, Glycerin diacetate heptanoate, glycerin diacetate hexanoate, glycerin diacetate pentanoate, glycerin diacetate oleate, glycerin acetate dicaplate, glycerin acetate dinonanoate, glycerin acetate dioctanoate, glycerin acetate diheptanoate , Glycerin acetate dicaproate, glycerin acetate divalerate, glycerin acetate jib Rate, glycerin dipropionate caprate, glycerin dipropionate laurate, glycerin dipropionate mistylate, glycerin dipropionate palmitate, glycerin dipropionate stearate, glycerin dipropionate oleate, glycerin tributyrate, glycerin trilate Pentanoate, glycerin monopalmitate, glycerin monostearate, glycerin distearate, glycerin propionate laurate, glycerin oleate propionate, and the like, but are not limited thereto, and these may be used alone or in combination. be able to.

  Among them, glycerin diacetate caprylate, glycerin diacetate pelargonate, glycerin diacetate caprate, glycerin diacetate traurate, glycerin diacetate myristate, glycerin diacetate palmitate, glycerin diacetate stearate, glycerin diacetate oleate preferable.

  Specific examples of diglycerin esters include diglycerin tetraacetate, diglycerin tetrapropionate, diglycerin tetrabutyrate, diglycerin tetravalerate, diglycerin tetrahexanoate, diglycerin tetraheptanoate, and diglycerin tetraheptanoate. Glycerin tetracaprylate, diglycerin tetraperargonate, diglycerin tetracaprate, diglycerin tetralaurate, diglycerin tetramistilate, diglycerin tetrapalmitate, diglycerin triacetate propionate, diglycerin triacetate butyrate, diglycerin Triacetate valerate, diglycerin triacetate hexanoate, diglycerin triacetate heptanoate, diglycerin triacetate caprylate, Glycerin triacetate perargonate, diglycerin triacetate caprate, diglycerin triacetate traurate, diglycerin triacetate mysylate, diglycerin triacetate palmitate, diglycerin triacetate stearate, diglycerin triacetate oleate, diglycerin diacetate dipropionate dipropionate Diacetate dibutyrate, diglycerin diacetate divalerate, diglycerin diacetate dihexanoate, diglycerin diacetate diheptanoate, diglycerin diacetate dicaprylate, diglycerin diacetate diperargonate, diglycerin di Acetate zika plate, diglycerin diacetate dilaurate, diglycerin diacetate dimisti Diglycerin diacetate dipalmitate, diglycerin diacetate distearate, diglycerin diacetate diolate, diglycerin acetate tripropionate, diglycerin acetate tributyrate, diglycerin acetate trivalerate, diglycerin acetate triacetate Hexanoate, diglycerin acetate triheptanoate, diglycerin acetate tricaprylate, diglycerin acetate tripelargonate, diglycerin acetate tricaplate, diglycerin acetate trilaurate, diglycerin acetate trimistylate, diglycerin acetate triacetate Palmitate, diglycerin acetate tristearate, diglycerin acetate triolate, diglycerin laurate, jig Examples include, but are not limited to, mixed acid esters of diglycerin such as lyserine stearate, diglycerin caprylate, diglycerin myristate, and diglycerol oleate. These can be used alone or in combination.

  Among these, diglycerin tetraacetate, diglycerin tetrapropionate, diglycerin tetrabutyrate, diglycerin tetracaprylate, and diglycerin tetralaurate are preferred.

  Specific examples of the polyalkylene glycol include, but are not limited to, polyethylene glycol and polypropylene glycol having an average molecular weight of 200 to 1,000, and these can be used alone or in combination.

  Specific examples of a compound in which an acyl group is bonded to a hydroxyl group of polyalkylene glycol include polyoxyethylene acetate, polyoxyethylene propionate, polyoxyethylene butyrate, polyoxyethylene valerate, polyoxyethylene caproate, Polyoxyethylene heptanoate, polyoxyethylene octanoate, polyoxyethylene nonanate, polyoxyethylene caprate, polyoxyethylene laurate, polyoxyethylene myristylate, polyoxyethylene palmitate, polyoxyethylene stearate , Polyoxyethylene oleate, polyoxyethylene linoleate, polyoxypropylene acetate, polyoxypropylene propionate, polyoxypropylene butyrate, polyoxypropylene Valerate, polyoxypropylene caproate, polyoxypropylene heptanoate, polyoxypropylene octanoate, polyoxypropylene nonanate, polyoxypropylene caprate, polyoxypropylene laurate, polyoxypropylene myristylate, polyoxy Examples include, but are not limited to, propylene palmitate, polyoxypropylene stearate, polyoxypropylene oleate, and polyoxypropylene linoleate, and these can be used alone or in combination.

  In the present invention, a composition comprising at least 80 to 98% by weight of a cellulose fatty acid ester in which at least a part of acyl groups of the cellulose fatty acid ester has 3 to 18 carbon atoms and 2 to 20% by weight of a polyhydric alcohol plasticizer is used. The resulting fiber has a strength S (unit: cN / dtex) and an elongation E (unit:%) satisfying the following expression.

6 ≦ S · E ^1/2 ≦ 10, 15 ≦ E ≦ 50
The above expression S · E ^1/2 simply shows the energy at which the fiber breaks, and is called toughness. Higher toughness indicates that the fibers are less likely to break.

  Cellulose fatty acid ester fibers satisfying the above formula require high energy when the fibers are cut, and thus have excellent durability.

  The elongation of the cellulose fatty acid ester fiber is 15 to 50%. When the elongation is 15% or more, yarn breakage does not frequently occur in a higher processing step such as weaving or knitting. The good elongation is more preferably 20 to 45%, and most preferably 20 to 40%.

  The present invention comprises a composition comprising at least a cellulose fatty acid ester in which at least a part of the acyl group of the cellulose fatty acid ester has 80 to 98% by weight of 3 to 18 carbon atoms and 2 to 20% by weight of a polyhydric alcohol plasticizer. The yield point stress of the fibers is between 0.5 and 1.5 cN / dtex. It is preferable that the yield point stress be in this range because the process passability at the time of producing a woven or knitted fabric is improved.

  The cellulose fatty acid ester fiber in the present invention preferably satisfies the above formula and has a strength of 0.9 to 3.0 cN / dtex. When the strength is 0.9 cN / dtex or more, it is preferable because the passability in a high-order processing step such as weaving or knitting is good and the strength of the final product is not insufficient. From the viewpoint of good strength characteristics, the higher the strength is, the more preferable it is. Specifically, it is more preferably 1.0 to 3.0 cN / dtex, and more preferably 1.1 to 3.0 cN / dtex. Most preferred. It is practically very difficult to obtain a fiber having a strength higher than 3.0 cN / dtex.

  The cellulose fatty acid ester fiber in the present invention preferably has an initial tensile resistance of 20 to 50 cN / dtex. By setting the initial tensile resistance to 20 cN / dtex or more, it is possible to give an appropriate beam (tension) and stiffness (waist) when made into a fabric. It is difficult to obtain cellulose fatty acid ester fibers having an initial tensile resistance higher than 50 cN / dtex.

  The boiling point of the cellulose fatty acid ester fiber in the present invention is preferably 0.5 to 10%. When the boiling water shrinkage ratio is in this range, thermal dimensional stability is good, and problems due to shrinkage do not occur in a dyeing step or a high-order processing step, and handling is not difficult.

  The single-fiber fineness of the cellulose fatty acid ester fiber in the present invention is preferably 0.5 to 100 dtex. If the single-fiber fineness is 0.5 dtex or more, the fiber can be obtained with good spinnability by a direct melt spinning method. Further, if the single yarn fineness is 100 dtex or less, the fiber structure can be applied to clothing fabrics and the like that require softness without excessively increasing the bending rigidity of the fiber structure. The single yarn fineness is more preferably 0.7 to 50 dtex, and most preferably 1 to 25 dtex.

  In the present invention, the U% (Worcester normal%) of the cellulose fatty acid ester fiber is preferably 3% or less. U% refers to fineness unevenness in the length direction of the fiber. U% of 3% or less is a fiber having excellent fineness uniformity, and the smaller the value, the more preferable. It is more preferably at most 2.5%, further preferably at most 2%. The U% measuring method will be described in detail in Examples.

  The cross-sectional shape of the cellulose fatty acid ester fiber in the present invention is not particularly limited, and may have a substantially perfect circular circular cross-section, or may be multi-lobed, flat, elliptical, W-shaped, or L-shaped. , S-shaped, X-shaped, H-shaped, C-shaped, cross-shaped, cross-shaped, hollow, etc. Further, it may be a composite fiber such as a core-sheath composite, an eccentric core-sheath composite, a side-by-side type composite, and a mixed fineness fiber. Furthermore, inorganic fine particles and organic compounds can be contained as necessary as matting agents, deodorants, flame retardants, yarn friction reducing agents, antioxidants, coloring pigments, electrostatic agents, antibacterial agents and the like. .

  The method for producing a fiber comprising a composition comprising at least a cellulose fatty acid ester having at least a part of an acyl group having 3 to 18 carbon atoms and a polyhydric alcohol plasticizer, which is excellent in the high elongation property in the present invention, Any of a melt spinning method, a wet spinning method, a dry spinning method, and a semi-wet semi-dry spinning method may be used. Above all, high quality long fibers can be obtained with high productivity, fiber cross section can be controlled arbitrarily, and various types of composite fibers such as core-sheath composite, eccentric core-sheath composite, side-by-side composite can be obtained. It does not use organic solvents that place a burden on the environment during production, has a low energy cost, makes it possible to draw fibers obtained by spinning by making use of good heat-fluidity characteristics, and also makes it possible to draw false twists. Considering that it becomes possible to easily perform false twisting and the like, the melt spinning method is most preferable.

  Illustrating a method for producing a cellulose fatty acid ester fiber by a melt spinning method, in a known melt extrusion spinning machine such as a pressure melter type or an extruder type, a composition comprising at least a cellulose fatty acid ester and a polyhydric alcohol plasticizer. After being heated and melted and extruded from the die, the extruded yarn passes through the region of the atmosphere heated by the use of the heating cylinder, is then cooled by the chimney, and the yarn is converged and wound by applying an oil agent.

  At this time, the spinning temperature is preferably set to 200 to 280 ° C. By setting the spinning temperature to 200 ° C. or higher, the melt viscosity of the composition is reduced, and melt-fracturing or poor spinning does not occur. By setting the spinning temperature to 280 ° C. or lower, the thermal decomposition of the composition is suppressed, and thus the obtained fiber is not colored, and a fiber suitable for clothing can be obtained. The spinning temperature is more preferably from 220 to 270 ° C, most preferably from 230 to 260 ° C.

  At the time of melt spinning, it is important to install a heating cylinder or a heat retaining cylinder immediately below the spinneret. By installing a heating cylinder or a heat retaining cylinder, the ambient temperature immediately below the base is increased, and cellulose fatty acid ester fibers having excellent toughness can be obtained.

  The temperature of the atmosphere below the base is preferably 80 to 280 ° C. The ambient temperature below the base is a temperature 30 mm directly below the base surface. When the ambient temperature under the base is less than 80 ° C., only fibers having the same fiber characteristics as those obtained without using a heating tube or a heat retaining tube can be obtained. When the temperature is higher than 280 ° C., breakage of single yarns and the like frequently occurs, and the yarn forming property becomes unstable. The temperature of the atmosphere under the base is more preferably 100 to 270 ° C.

  The length of the heating cylinder or the heat retaining cylinder used for heating under the base is preferably 50 to 400 mm, and more preferably 100 to 300 mm, in consideration of the effect of facilitating the thinning deformation of the spun yarn and the workability of the spinning. Is more preferable.

  The spinning speed is preferably from 700 to 2000 m / min. By setting the spinning speed to 700 to 2000 m / min, molecular orientation is promoted and toughness is improved. The spinning speed is more preferably from 750 to 2,000 m / min, most preferably from 800 to 2,000 m / min.

Hereinafter, the present invention will be described in more detail with reference to examples. The respective characteristic values in the examples were obtained by the following methods, but the present invention is not limited to these.
A. Degree of substitution of cellulose fatty acid ester The method for calculating the degree of substitution of cellulose fatty acid ester in which an acetyl group and an acyl group are bonded to cellulose is as follows.

  0.9 g of a cellulose fatty acid ester which had been made absolutely dry by vacuum drying at 80 ° C. for 8 hours was weighed, 35 ml of acetone and 15 ml of dimethyl sulfoxide were added and dissolved, and then 50 ml of acetone was further added. While stirring, 30 ml of a 0.5 N aqueous sodium hydroxide solution was added, and the mixture was saponified for 2 hours. After adding 50 ml of hot water and washing the side surface of the flask, titration was performed 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 completion of the titration was diluted 100-fold, and the composition of the organic acid was measured using an ion chromatograph. The degree of substitution was calculated by the following equation from the measurement results and the results of acid composition analysis by ion chromatography.

TA = (BA) × F / (1000 × W)
DSace = (162.14 × TA) / [1- (Mwace− (16.00 + 1.01) × TA + {1- (Mwacy− (16.00 + 1.01) × TA} × Acy / Ace]
DSacy = DSace × (Acy / Ace)
TA: Total amount of organic acid (ml)
A: Sample titer (ml)
B: Blank test titer (ml)
F: titer of sulfuric acid W: sample weight (g)
DSace: Degree of substitution of acetyl group DSacy: Degree of substitution of acyl group Mwace: Molecular weight of acetic acid Mwacy: Molecular weight of other organic acid Acy / Ace: Molar ratio of acetic acid (Ace) to other organic acid (Acy) 162.14 : Molecular weight of repeating unit of cellulose 16.00: atomic weight of oxygen 1.01: atomic weight of hydrogen Weight average molecular weight (Mw)
The cellulose fatty acid ester was completely dissolved in chloroform to a concentration of 0.01% by weight to prepare 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: Shodex K-805L manufactured by Showa Denko, two connected Detector: Waters2410 Differential refractometer RI
Mobile phase solvent: chloroform Flow rate: 1.0 ml / min Injection volume: 200 μl
C. Strength, elongation, initial tensile resistance, and yield stress were measured based on JIS L 1013 (1999). Tensileon UCT-100 manufactured by Orientec Co., Ltd. was subjected to a tensile test under the conditions of a sample length of 20 cm and a tensile speed of 20 cm / min, and the value obtained by dividing the stress at the point showing the maximum load by the fineness was taken as the fiber strength (cN / dtex). ). The elongation at break was defined as the elongation (%) of the fiber.

  The strength and elongation were measured with a multifilament yarn, and the number of measurements was five, and the average values were taken as the strength and elongation.

  The initial tensile resistance (cN / dtex) was calculated based on JIS L 1013 (1999) (Test method for chemical fiber filament yarn) 8.10 (initial tensile resistance).

  The initial tensile resistance was measured using a multifilament yarn, and the number of measurements was five, and the average value was defined as the initial tensile resistance.

The yield point stress (cN / dtex) was a value obtained by dividing the load at the time of yielding in the tensile test by the fineness.
D. U% (Worcester normal%)
The U% measurement was obtained by measuring under the following conditions using a Worcester Tester 4-CX manufactured by Zellbeger Worcester.

Measurement speed: 200 m / min Measurement time: 1 min Twist: S twist, 12000 / min Note that U% is measured with a multifilament yarn. The number of measurements was three, and the average value was U%.
E. FIG. Boiling water shrinkage rate After the fiber (multifilament yarn) is skeined and the sample length L0 is measured under a load of 0.09 cN / dtex, a treatment is performed in boiling water for 15 minutes with no load. After the treatment, the sample was air-dried, and then the sample length L1 was measured under a load of 0.09 cN / dtex, and the following equation: boiling water shrinkage (%) = {(L0−L1) / L0} × 100
The number of measurements was five, and the average value was defined as the boiling water shrinkage.

Example 1
Cellulose acetate propionate as a cellulose fatty acid ester (degree of substitution of acetyl group: 0.1, degree of substitution of propionyl group: 2.6, weight average molecular weight: 160,000; CAP-482-20 manufactured by Eastman Chemical Company) 90% by weight and 10% by weight of glycerin diacetate monooleate were kneaded at 190 ° C. using a biaxial extruder, and cut to about 5 mm to obtain a cellulose fatty acid ester composition pellet.

  The pellets were vacuum-dried at 80 ° C. for 8 hours, melted at a melter temperature of 235 ° C., introduced into a melt spinning pack at a spinning temperature of 235 ° C., and discharged at a discharge rate of 13.4 g / min. It was spun from a die having 36 holes of 23 mmφ-0.30 mmL. The spun yarn is passed through a heating tube (length: 150 mm) installed under the base (temperature under the base: 150 ° C.), cooled by a chimney wind at a temperature of 25 ° C. and a wind speed of 0.3 m / sec to apply an oil agent. After being converged by the first godet roller rotating at 800 m / min, the winding tension is set to 0.1 cN / dtex via the second godet roller rotating at the same speed as the first godet roller. It was wound up with a winder rotating at the following speed. The resulting fiber (167 dtex-36 filaments; single yarn fineness: 4.6 dtex) has a strength of 1.17 cN / dtex, an elongation of 27.7%, a yield point stress of 0.44 cN / dtex, and an initial tensile resistance. Was 24.0 cN / dtex, the boiling water shrinkage was 3.8%, and the U% was 0.7%. The toughness of this fiber was 6.2, and it had good high elongation characteristics (see Table 1).

Example 2
Cellulose acetate propionate as a cellulose fatty acid ester (degree of substitution of acetyl group: 0.1, degree of substitution of propionyl group: 2.6, weight average molecular weight: 160,000; CAP-482-20 manufactured by Eastman Chemical Company) 90% by weight and 10% by weight of glycerin diacetate monooleate were kneaded at 190 ° C. using a biaxial extruder, and cut to about 5 mm to obtain a cellulose fatty acid ester composition pellet.

  The pellets were vacuum-dried at 80 ° C. for 8 hours, melted at a melter temperature of 235 ° C., introduced into a melt spinning pack at a spinning temperature of 235 ° C., and discharged at a discharge rate of 13.4 g / min. It was spun from a die having 36 holes of 23 mmφ-0.30 mmL. The spun yarn is passed through a heating cylinder (length: 150 mm) installed under the base (temperature under the base: 175 ° C), cooled by a chimney wind at a temperature of 25 ° C and a wind speed of 0.3 m / sec to apply an oil agent. After being converged by the first godet roller rotating at 800 m / min, the winding tension is set to 0.1 cN / dtex via the second godet roller rotating at the same speed as the first godet roller. It was wound up with a winder rotating at the following speed. The resulting fiber (167 dtex-36 filament; single yarn fineness: 4.6 dtex) has a strength of 1.20 cN / dtex, an elongation of 30.3%, a yield point stress of 0.48 cN / dtex, and an initial tensile resistance. Was 23.6 cN / dtex, the boiling water shrinkage was 4.0%, and the U% was 1.0%. The toughness of this fiber was 6.6, and it had very good elongation properties (see Table 1).

Example 3
Cellulose acetate propionate as a cellulose fatty acid ester (degree of substitution of acetyl group: 0.1, degree of substitution of propionyl group: 2.6, weight average molecular weight: 160,000; CAP-482-20 manufactured by Eastman Chemical Company) 93% by weight and 7% by weight of polyethylene glycol (PEG600) having an average molecular weight of 600 were kneaded at 190 ° C. using a twin-screw extruder and cut to about 5 mm to obtain cellulose fatty acid ester composition pellets.

  The pellets were vacuum-dried at 80 ° C. for 8 hours, melted at a melter temperature of 238 ° C., introduced into a melt spinning pack at a spinning temperature of 238 ° C., and discharged at a discharge rate of 8.4 g / min. It was spun from a die having 24 holes of 27 mmφ-0.65 mmL. The spun yarn is passed through a heating cylinder (length: 150 mm) installed under the base (temperature under the base: 200 ° C.), cooled by a chimney wind at 25 ° C. and a wind speed of 0.3 m / sec to apply an oil agent. After being converged by the first godet roller rotating at 1000 m / min, the winding tension is set to 0.08 cN / dtex via the second godet roller rotating at the same speed as the first godet roller. It was wound up with a winder rotating at the following speed. The strength of the obtained fiber (84 dtex-24 filament; single yarn fineness 3.5 dtex) is 1.32 cN / dtex, elongation is 25.8%, yield point stress is 0.60 cN / dtex, initial tensile resistance Was 28.2 cN / dtex, the boiling water shrinkage was 4.4%, and U% was 1.1%. The toughness of this fiber was 6.7, and it had good high elongation characteristics (see Table 1).

Example 4
As a cellulose fatty acid ester, cellulose acetate butyrate (degree of substitution of acetyl group: 1.0, degree of substitution of butyryl group: 1.7, weight average molecular weight: 15,000; CAB-381-20 manufactured by Eastman Chemical Company) 91 % By weight and 9% by weight of diglycerin tetracaprylate were kneaded at 190 ° C. using a biaxial extruder, and cut to about 5 mm to obtain cellulose fatty acid ester composition pellets.

  The pellets were vacuum dried at 80 ° C. for 8 hours, melted at a melter temperature of 240 ° C., introduced into a melt spinning pack at a spinning temperature of 240 ° C., and discharged at a discharge rate of 10.5 g / min. It was spun from a die having 12 holes of 23 mmφ-0.30 mmL. The spun yarn is passed through a heating cylinder (length: 150 mm) installed under the base (temperature under the base: 125 ° C.), cooled by a chimney wind at 25 ° C. and a wind speed of 0.3 m / sec, and an oil agent is applied. After being converged by the first godet roller rotating at 1250 m / min, the winding tension is set to 0.09 cN / dtex through the second godet roller rotating at the same speed as the first godet roller. It was wound up with a winder rotating at the following speed. The strength of the obtained fiber (84 dtex-12 filament; single yarn fineness 7.0 dtex) is 1.28 cN / dtex, elongation is 24.8%, yield point stress is 0.59 cN / dtex, initial tensile resistance Was 28.3 cN / dtex, the boiling water shrinkage was 4.6%, and the U% was 0.6%. The toughness of this fiber was 6.4, and it had good high elongation characteristics (see Table 1).

Example 5
Cellulose acetate propionate as a cellulose fatty acid ester (degree of substitution of acetyl group: 0.1, degree of substitution of propionyl group: 2.6, weight average molecular weight: 160,000; CAP-482-20 manufactured by Eastman Chemical Company) 13% by weight of polyoxyethylene laurate having 87% by weight and a lauryl group bonded to a terminal hydroxyl group of polyethylene glycol having an average molecular weight of 200 is kneaded at 190 ° C. using a twin-screw extruder and cut to about 5 mm to obtain cellulose. A fatty acid ester composition pellet was obtained.

  The pellets were vacuum dried at 80 ° C. for 8 hours, melted at a melter temperature of 230 ° C., introduced into a melt spinning pack at a spinning temperature of 230 ° C., and discharged at a discharge rate of 16.5 g / min. It was spun from a die having 48 holes of 30 mmφ-0.35 mmL. The spun yarn is passed through a heating cylinder (length: 150 mm) installed under the base (temperature under the base: 190 ° C), cooled by a chimney wind at 25 ° C and a wind speed of 0.3 m / sec, and an oil agent is applied. After being converged by the first godet roller rotating at 1500 m / min, the winding tension is 0.10 cN / dtex through the second godet roller rotating at the same speed as the first godet roller. It was wound up with a winder rotating at the following speed. The strength of the obtained fiber (110 dtex-48 filament; single fiber fineness of 2.3 dtex) is 1.33 cN / dtex, elongation is 24.9%, yield point stress is 0.61 cN / dtex, initial tensile resistance Was 30.3 cN / dtex, the boiling water shrinkage was 5.0%, and the U% was 1.0%. The toughness of this fiber was 6.6, and it had good high elongation characteristics (see Table 1).

Example 6
Cellulose acetate propionate as a cellulose fatty acid ester (degree of substitution of acetyl group: 0.1, degree of substitution of propionyl group: 2.6, weight average molecular weight: 160,000; CAP-482-20 manufactured by Eastman Chemical Company) 85% by weight and 15% by weight of glycerin diacetate monolaurate were kneaded at 185 ° C. using a biaxial extruder, and cut to about 5 mm to obtain a cellulose fatty acid ester composition pellet.

  The pellets were vacuum dried at 80 ° C. for 8 hours, melted at a melter temperature of 225 ° C., introduced into a melt spinning pack at a spinning temperature of 225 ° C., and discharged at a discharge rate of 14.2 g / min. It was spun from a die having 48 holes of 34 mmφ-0.50 mmL. The spun yarn is passed through a heating cylinder (length: 150 mm) installed under the base (temperature under the base: 150 ° C.), cooled by a chimney wind having a wind speed of 0.3 m / sec, and applied with an oil agent to converge. Then, it is taken up by a first godet roller rotating at 850 m / min, and a speed at which the winding tension becomes 0.1 cN / dtex via a second godet roller rotating at the same speed as the first godet roller. And wound it up with a winder rotating. The obtained fiber (167 dtex-48 filaments; single yarn fineness: 3.5 dtex) has a strength of 1.05 cN / dtex, an elongation of 34.0%, a yield point stress of 0.42 cN / dtex, and an initial tensile resistance. Was 21.0 cN / dtex, the boiling water shrinkage was 4.7%, and the U% was 1.3%. This fiber had a toughness of 6.1 and had good high elongation properties (see Table 1).

Example 7
240 parts by weight of acetic acid and 67 parts by weight of propionic acid were added to 100 parts by weight of cellulose (dissolving pulp from Nippon Paper Industries, 92% by weight of α-cellulose) and mixed at 50 ° C. for 30 minutes. After cooling the mixture to room temperature, 172 parts by weight of acetic anhydride and 168 parts by weight of propionic anhydride cooled in an ice bath 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. When the temperature exceeded 40 ° C. in the esterification reaction, the mixture 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 ester was separated by filtration, washed with water, and dried at 60 ° C. for 4 hours. The degree of substitution of the obtained cellulose fatty acid ester was 2.4 (acetyl group 1.9, propionyl group 0.5), and the weight average molecular weight was 12,000,000.

  80% by weight of this cellulose fatty acid ester and 20% by weight of polyethylene glycol having an average molecular weight of 600 were kneaded at 220 ° C. using a biaxial extruder, and cut to about 5 mm to obtain a cellulose fatty acid ester composition pellet.

  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 at a spinning temperature of 255 ° C., and discharged at a discharge rate of 15.0 g / min. It was spun from a die having 24 holes of 25 mmφ-0.50 mmL. The spun yarn is passed through a heating cylinder (length: 100 mm) installed under the cap (temperature below the cap is 240 ° C.), cooled by a chimney wind having a wind speed of 0.3 m / sec, and applied with an oil agent to converge. Then, it is taken up by a first godet roller rotating at 1500 m / min, and a speed at which the winding tension becomes 0.1 cN / dtex via a second godet roller rotating at the same speed as the first godet roller. And wound it up with a winder rotating. The strength of the obtained fiber (100 dtex-24 filament; single yarn fineness: 4.2 dtex) is 1.40 cN / dtex, elongation is 27.2%, yield point stress is 0.65 cN / dtex, initial tensile resistance Was 27.4 cN / dtex, the boiling water shrinkage was 4.0%, and the U% was 1.0%. The toughness of this fiber was 7.3, and it had good high elongation characteristics (see Table 1).

Example 8
Kneading 85% by weight of the cellulose fatty acid ester used in Example 7 and 15% by weight of polyethylene glycol having an average molecular weight of 600 using a twin-screw extruder at 230 ° C. using a twin-screw extruder, and cutting to about 5 mm. Thus, a cellulose fatty acid ester composition pellet was obtained.

  The pellets were dried in a vacuum at 80 ° C. for 8 hours, melted at a melter temperature of 250 ° C., introduced into a melt spinning pack at a spinning temperature of 265 ° C., and discharged at a discharge rate of 30.0 g / min. It was spun from a die having 36 holes with a diameter of 20 mm-0.40 mmL. This spun yarn is passed through the inside of a heating cylinder (length: 175 mm) installed under the base (temperature under the base: 250 ° C.), cooled by a chimney wind at 25 ° C. and a wind speed of 0.3 m / sec, and an oil agent is applied. After being converged by the first godet roller rotating at 1800 m / min, the winding tension is set to 0.1 cN / dtex via the second godet roller rotating at the same speed as the first godet roller. It was wound up with a winder rotating at the following speed. The resulting fiber (167 dtex-36 filament; single yarn fineness: 4.6 dtex) has a strength of 1.42 cN / dtex, an elongation of 24.0%, a yield point stress of 0.67 cN / dtex, and an initial tensile resistance. Was 31.3 cN / dtex, the boiling water shrinkage was 5.0%, and the U% was 1.1%. The toughness of this fiber was 7.0, and it had good high elongation properties (see Table 1).

Comparative Example 1
Cellulose acetate propionate as a cellulose fatty acid ester (degree of substitution of acetyl group: 0.1, degree of substitution of propionyl group: 2.6, weight average molecular weight: 160,000; CAP-482-20 manufactured by Eastman Chemical Company) 90% by weight and 10% by weight of glycerin diacetate monooleate were kneaded at 190 ° C. using a biaxial extruder, and cut to about 5 mm to obtain a cellulose fatty acid ester composition pellet.

  The pellets were vacuum-dried at 80 ° C. for 8 hours, melted at a melter temperature of 235 ° C., introduced into a melt spinning pack at a spinning temperature of 235 ° C., and discharged at a discharge rate of 13.4 g / min. It was spun from a die having 36 holes of 23 mmφ-0.30 mmL. The spun yarn is cooled by a chimney wind at a temperature of 25 ° C. and a wind speed of 0.3 m / sec, and is converged by applying an oil agent. Then, the spun yarn is taken up by a first godet roller rotating at 800 m / min. Winding was performed by a winder rotating at a speed at which the winding tension was 0.1 cN / dtex, via a second godet roller rotating at the same speed as the dead roller. The strength of the obtained fiber (167 dtex-36 filament; single yarn fineness: 4.6 dtex) is 1.09 cN / dtex, elongation is 20.7%, yield point stress is 0.40 cN / dtex, initial tensile resistance Was 24.4 cN / dtex, the boiling water shrinkage was 4.0%, and the U% was 0.5%. The toughness of this fiber was 5.0, and the toughness was inferior (see Table 2).

Comparative Example 2
Cellulose acetate propionate as a cellulose fatty acid ester (degree of substitution of acetyl group: 0.1, degree of substitution of propionyl group: 2.6, weight average molecular weight: 160,000; CAP-482-20 manufactured by Eastman Chemical Company) 90% by weight and 10% by weight of glycerin diacetate monooleate were kneaded at 190 ° C. using a biaxial extruder, and cut to about 5 mm to obtain a cellulose fatty acid ester composition pellet.

  The pellets were vacuum-dried at 80 ° C. for 8 hours, melted at a melter temperature of 235 ° C., introduced into a melt spinning pack at a spinning temperature of 235 ° C., and discharged at a discharge rate of 13.4 g / min. It was spun from a die having 36 holes of 23 mmφ-0.30 mmL. The spun yarn is passed through the inside of a heating cylinder (length: 150 mm) installed under the base (temperature under the base: 70 ° C.), cooled by a chimney wind at a temperature of 25 ° C. and a wind speed of 0.3 m / sec to apply an oil agent. After being converged by the first godet roller rotating at 800 m / min, the winding tension is set to 0.1 cN / dtex via the second godet roller rotating at the same speed as the first godet roller. It was wound up with a winder rotating at the following speed. The resulting fiber (167 dtex-36 filament; single yarn fineness: 4.6 dtex) has a strength of 1.10 cN / dtex, an elongation of 21.1%, a yield point stress of 0.41 cN / dtex, and an initial tensile resistance. Was 24.3 cN / dtex, the boiling water shrinkage was 4.0%, and the U% was 0.6%. The toughness of this fiber was 5.1, indicating inferior toughness (see Table 2).

Comparative Example 3
Cellulose acetate propionate as a cellulose fatty acid ester (degree of substitution of acetyl group: 0.1, degree of substitution of propionyl group: 2.6, weight average molecular weight: 160,000; CAP-482-20 manufactured by Eastman Chemical Company) 90% by weight and 10% by weight of glycerin diacetate monooleate were kneaded at 190 ° C. using a biaxial extruder, and cut to about 5 mm to obtain a cellulose fatty acid ester composition pellet.

  The pellets were vacuum-dried at 80 ° C. for 8 hours, melted at a melter temperature of 235 ° C., introduced into a melt spinning pack at a spinning temperature of 235 ° C., and discharged at a discharge rate of 13.4 g / min. It was spun from a die having 36 holes of 23 mmφ-0.30 mmL. The spun yarn is passed through a heating cylinder (length: 150 mm) installed under the cap (temperature under the cap is 285 ° C.), cooled by a chimney wind at 25 ° C. and a wind speed of 0.3 m / sec, and an oil agent is applied. After being converged by the first godet roller rotating at 800 m / min, the winding tension is set to 0.1 cN / dtex via the second godet roller rotating at the same speed as the first godet roller. Attempted winding many times with a winder rotating at the speed, but the temperature of the heating cylinder was too high, so the yarn was frequently broken in the heating cylinder at the time of threading, and the wound yarn could not be obtained. .

Comparative Example 4
Cellulose acetate propionate as a cellulose fatty acid ester (degree of substitution of acetyl group: 0.1, degree of substitution of propionyl group: 2.6, weight average molecular weight: 160,000; CAP-482-20 manufactured by Eastman Chemical Company) 90% by weight and 10% by weight of polyethylene glycol (PEG600) having an average molecular weight of 600 were kneaded at 190 ° C. using a biaxial extruder, and cut to about 5 mm to obtain a cellulose fatty acid ester composition pellet.

  The pellets were vacuum-dried at 80 ° C. for 8 hours, melted at a melter temperature of 235 ° C., introduced into a melt spinning pack at a spinning temperature of 235 ° C., and discharged at a discharge rate of 24.3 g / min. It was spun from a die having 24 holes of 23 mmφ-0.30 mmL. The spun yarn is passed through a heating tube (length: 150 mm) installed under the base (temperature under the base: 150 ° C.), cooled by a chimney wind at a temperature of 25 ° C. and a wind speed of 0.3 m / sec to apply an oil agent. After being converged by the first godet roller rotating at 2200 m / min, the winding tension is set to 0.1 cN / dtex via the second godet roller rotating at the same speed as the first godet roller. I tried many times to wind with a winder rotating at the speed, but because the spinning tension was too high, thread breakage with the godet roller occurred frequently during yarn hooking, and it was not possible to obtain a wound yarn .

Comparative Example 5
Cellulose acetate propionate as a cellulose fatty acid ester (degree of substitution of acetyl group: 0.1, degree of substitution of propionyl group: 2.6, weight average molecular weight: 160,000; CAP-482-20 manufactured by Eastman Chemical Company) 75% by weight and 25% by weight of glycerin diacetate monolaurate were kneaded at 185 ° C. using a biaxial extruder and cut to about 5 mm to obtain a cellulose fatty acid ester composition pellet.

  The pellets were vacuum dried at 80 ° C. for 8 hours, melted at a melter temperature of 220 ° C., introduced into a melt spinning pack at a spinning temperature of 220 ° C., and discharged at a discharge rate of 13.3 g / min. It was spun from a die having 18 holes of 27 mmφ-0.54 mmL. The spun yarn is passed through a heating cylinder (length: 150 mm) installed below the base (temperature below the base: 170 ° C), cooled by a chimney wind at 25 ° C and a wind speed of 0.3 m / sec, and an oil agent is applied. After being converged by the first godet roller rotating at 800 m / min, the winding tension is set to 0.1 cN / dtex via the second godet roller rotating at the same speed as the first godet roller. It was wound up with a winder rotating at the following speed. The strength of the obtained fiber (166 dtex-48 filaments; single fiber fineness 3.5 dtex) is 0.79 cN / dtex, elongation is 39.5%, yield point stress is 0.31 cN / dtex, initial tensile resistance Was 16.5 cN / dtex, the boiling water shrinkage was 6.0%, and the U% was 3.2%. The toughness of this fiber was 5.0, and the toughness was inferior (see Table 2).

Comparative Example 6
Cellulose acetate propionate as a cellulose fatty acid ester (degree of substitution of acetyl group: 0.1, degree of substitution of propionyl group: 2.6, weight average molecular weight: 160,000; CAP-482-20 manufactured by Eastman Chemical Company) 87% by weight and 13% by weight of polyoxyethylene laurate were kneaded at 190 ° C. using a biaxial extruder, and cut to about 5 mm to obtain a cellulose fatty acid ester composition pellet.

  The pellets were vacuum dried at 80 ° C. for 8 hours, melted at a melter temperature of 230 ° C., introduced into a melt spinning pack at a spinning temperature of 230 ° C., and discharged at a discharge rate of 16.5 g / min. It was spun from a die having 48 holes of 30 mmφ-0.35 mmL.

The spun yarn is cooled by a chimney wind at a temperature of 25 ° C. and a wind speed of 0.3 m / sec, and is converged by applying an oil agent. Winding was performed by a winder rotating at a speed at which the winding tension was 0.1 cN / dtex, via a second godet roller rotating at the same speed as the dead roller. The strength of the obtained fiber (110 dtex-48 filament; single fiber fineness of 2.3 dtex) is 1.26 cN / dtex, elongation is 15.2%, yield point stress is 0.48 cN / dtex, initial tensile resistance Was 31.2 cN / dtex, the boiling water shrinkage was 4.8%, and the U% was 1.1%. The toughness (strength x elongation ^1/2 ) of this fiber was 4.9, indicating poor toughness (see Table 2).

Comparative Example 7
Cellulose acetate propionate as a cellulose fatty acid ester (degree of substitution of acetyl group: 0.1, degree of substitution of propionyl group: 2.6, weight average molecular weight: 160,000; CAP-482-20 manufactured by Eastman Chemical Company) 90% by weight and 10% by weight of glycerin diacetate monooleate were kneaded at 190 ° C. using a biaxial extruder, and cut to about 5 mm to obtain a cellulose fatty acid ester composition pellet.

  The pellets were vacuum dried at 80 ° C. for 8 hours, melted at a melter temperature of 235 ° C., introduced into a melt spinning pack at a spinning temperature of 235 ° C., and discharged at a discharge rate of 8.3 g / min. It was spun from a die having 36 holes of 23 mmφ-0.30 mmL. The spun yarn is passed through a heating tube (length: 150 mm) installed under the base (temperature under the base: 150 ° C.), cooled by a chimney wind at a temperature of 25 ° C. and a wind speed of 0.3 m / sec to apply an oil agent. After being converged by the first godet roller rotating at 500 m / min, the winding tension is set to 0.1 cN / dtex via the second godet roller rotating at the same speed as the first godet roller. It was wound up with a winder rotating at the following speed. The resulting fiber (166 dtex-36 filaments; single yarn fineness: 4.6 dtex) has a strength of 1.01 cN / dtex, an elongation of 29.5%, a yield point stress of 0.38 cN / dtex, and an initial tensile resistance. Was 22.0 cN / dtex, the boiling water shrinkage was 4.0%, and the U% was 0.5%. The toughness of this fiber was 5.5, which was inferior in toughness (see Table 2).

  The obtained fibers can be used as clothing fibers, industrial fibers, nonwoven fabrics, and the like, and can be particularly preferably used as clothing fibers.

Claims (4)

A fiber comprising a composition comprising at least 80 to 98% by weight of a cellulose fatty acid ester in which at least a part of the acyl groups of the cellulose fatty acid ester has 3 to 18 carbon atoms and 2 to 20% by weight of a polyhydric alcohol plasticizer. A cellulose fatty acid ester fiber characterized in that the fiber has a strength S (cN / dtex) and an elongation E (%) satisfying the following expression.
6 ≦ SE ^1/2 ≦ 10
15 ≦ E ≦ 50   A fiber comprising a composition comprising at least 80 to 98% by weight of a cellulose fatty acid ester in which at least a part of the acyl groups of the cellulose fatty acid ester has 3 to 18 carbon atoms and 2 to 20% by weight of a polyhydric alcohol plasticizer. The cellulose fatty acid ester fiber according to claim 1, wherein the fiber has a yield point stress of 0.5 to 1.5 cN / dtex.   The cellulose fatty acid ester fiber according to claim 1 or 2, wherein the cellulose fatty acid ester in which at least a part of the acyl group of the cellulose fatty acid ester has 3 to 18 carbon atoms is cellulose acetate propionate.   At the time of melt spinning a composition comprising at least a cellulose ester having at least a part of the acyl group of a cellulose fatty acid having 3 to 18 carbon atoms and a polyhydric alcohol plasticizer, a spinning temperature of 200 to 280 ° C. and a spinning speed are used. The method for producing a cellulose fatty acid ester fiber, wherein the temperature is set to 700 to 2000 m / min and the ambient temperature under the die is set to 80 to 280 ° C.