JPH0931744A - Man-made cellulosic fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain cellulosic fibers having crystalline properties of cellulose II type having respectively prescribed X-ray crystallinity, X-ray orientation and viscosity-average polymerization degree, high in wet strength, wet elastic modulus, excellent in resistance to fibrillation and suitable for clothing. SOLUTION: This cellulosic fiber has crystalline properties of cellulose II type having >=40% X-ray crystallinity, 80-90% X-ray orientation, >=258 deg.C at the maximum tanδ in dynamic viscoelasticity in >=200 deg.C. The cellulosic fiber is obtained by, e.g. preparing a spinning solution by dissolving purified cotton linters in a cuprammonium solution, filtered and deaerating, then extruding the spinning solution from spinning nozzles into a coagulant.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a regenerated cellulose fiber which has high strength and elastic modulus and is suitable for use in clothing which is difficult to be fibrillated.

[0002]

BACKGROUND OF THE INVENTION Viscose rayon has low mechanical properties, especially when wet. To illustrate the strength and elongation properties of a typical viscose rayon used for clothing, the dry elastic modulus is 85 g / d, the wet elastic modulus is 5 g / d, the dry strength is 1.8 g / d, and the wet strength is 0.85 g / d. It is significantly inferior to the chemical fiber for clothing which is opposed by d and the like. On the other hand, it is difficult to fibrillate, and has excellent handling performance during processing and consumption performance such as washing resistance. On the other hand, artificial cellulosic fibers produced by organic solvent spinning such as TENCEL (trade name, a product of Courtalls Co., Ltd.) have excellent mechanical strength, but easily fibrillize during processing, washing or wearing, and have a drawback of low rubbing resistance. is there. Although cupra ammonium rayon is slightly superior in fibril resistance to organic solvent-spun cellulose fibers such as Tencel, it is not a cellulose fiber material having a satisfactory level of fibrillation resistance. In order to improve the abrasion resistance of the artificial cellulose fiber, for example, the invention of the crosslinking treatment of the artificial cellulose fiber described in JP-A-5-117970 and the like has been made, but the abrasion resistance is practically satisfactory. It is not a processing method that can be improved to. Artificial cellulose fibers having excellent fibril resistance while ensuring high mechanical strength, particularly cellulose fibers for clothing, are not known.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide an artificial cellulose fiber which is difficult to be fibrillated and yet has high wet strength and elastic modulus.

[0004]

The object of the present invention is to have an X-ray crystallinity of 40% or more and an X-ray orientation of 80% or more.
Ta in dynamic viscoelasticity below 0% and above 200 ° C
It is achieved by a cellulose fiber having a type II crystallinity of which the maximum temperature of nδ is 258 ° C. or higher and the viscosity average degree of polymerization is 100 or more and less than 1300.

Cellulose fibers of the present invention having type II crystallinity (hereinafter referred to as type II cellulose fibers)
Shows a fibrillation resistance value of 90 or more, preferably 95 or more, which is defined in Examples described later, and the fibrillation resistance thereof is comparable to that of a general-purpose viscose rayon, but mechanical properties, especially under wet conditions. It has a high level of mechanical properties. Typical mechanical properties (JISL 1013) obtained for the type II cellulose fiber of the present invention are as follows.

Dry physical properties Wet physical properties Strength (g / d) 2-3 1.0-1.5 Elongation (%) 10-15 15-20 Elastic modulus (g / d) 100-200 10-20 According to the present invention The maximum temperature (Tmax) of tan δ of 200 ° C. or higher in the dynamic viscoelasticity of artificial cellulose fiber is 2
It is 58 ° C or higher. Although no upper limit is set for Tmax,
Since the decomposition of cellulose begins at a temperature of 330 ° C. or higher, it becomes meaningless to specify the physical properties of cellulose fiber as a practical fiber material at a temperature higher than this. here,
The value of tan δ in the dynamic viscoelasticity referred to in the present invention is 100 Hz at a frequency of 100 Hz using a DMS200 type viscoelasticity spectrometer manufactured by Seiko Denshi Kogyo Co., Ltd.
It is measured at 350 ° C.

In the case of type II cellulose fiber, the maximum peak of the tan δ value at 200 ° C. or higher is based on the micro Brownian motion of the cellulose molecular main chain and is called α dispersion (Polymer Journal Vol. 18, N.
o. 1, pp 1-14 [1986]). This peak temperature (Tmax) relatively represents the amorphous density of the cellulose fiber, and the higher the temperature, the higher the amorphous density. The present inventors have found that a remarkable correlation is found between the peak temperature (Tmax) and the ease of fibrillation of the type II cellulose fiber, and that the type II cellulose fiber having Tmax of 258 ° C. or higher is described later. Even after stirring with a home mixer for 20 minutes in water, only fine fibrils are generated on the surface of the fiber, the morphology of the fibril is retained, and the mechanical properties of the fibril and abrasion resistance of the fiber are practically used. I learned that it is practically retained. On the other hand, Tmax is 25
Type II cellulose fibers with an amorphous density of less than 8 ° C are easily fibrillated by mechanical stimulation in the presence of water. Therefore, the fibers may be significantly fibrillated by rubbing in the jet dyeing process, and the wearer's movement and washing may be It is inevitable that fibrillation will occur even by rubbing in the process of. Therefore, the type II cellulose fiber having Tmax of less than 258 ° C is not a preferable material as a fiber for a general outer garment, except for applications in a very limited field such as a lining and a textile product subjected to sandwashing.

A general-purpose regular viscose rayon, which is one of the representative examples of type II cellulose fibers, has a Tmax of 2
Although it is a material with a fibrillarization resistance of around 70 ° C or higher, or over 280 ° C, the viscose rayon has a low X-ray crystallinity, so that mechanical properties, particularly wetness, are as described above. Lower strength 1
The mechanical properties are remarkably inferior, such as around g / d or less, and an elastic modulus around 5 to 40 g / d or less, which hinders the use of artificial cellulose fibers for outerwear applications. The Tmax of cupranmonium-yeon and lyocell, which are other typical examples of type II cellulose fibers, is 245 ° C to 256 ° for commercially available raw yarn materials.
C and 230 ° C. to 250 ° C., and the fibrillation degree evaluation value after the home mixer agitation treatment for 20 minutes in water described below is 100 for the general-purpose regular viscose rayon, while it is 70 for each. It was confirmed that it is a material with significantly inferior fibrillation resistance, indicating the following before and after.

The type II cellulose fiber according to the present invention is a cellulose fiber having an X-ray crystallinity of 40% or more. The type II cellulose fibers having an X-ray crystallinity of less than 40% are not suitable as a cellulose fiber material for outer garment applications because of their mechanical properties, particularly those under wet conditions. The crystallinity referred to in the present invention is the Rotor Flex RU-20 manufactured by Rigaku Denki Co., Ltd., which has a wide angle X-ray diffraction pattern and a scintillation counter.
It is calculated from the measurement by the reflection method with the 0PL type X-ray diffractometer. In the measurement, in order to eliminate the influence of the crystal orientation, the fiber was finely chopped into a powder and molded into a tablet before the measurement. The crystallinity is a diffraction peak (peak height It) at 2θ = 12 ° corresponding to the (101) plane.
Draw a tangent line tangent to 2θ = 10 and 16 °, and
The height (Iu) of the tangent line of the above was calculated and calculated from the following equation [A. Isogai et al .: Journal of the Textile Society, Vol. Four
6, No. 8, 1990).

X-ray crystallinity = [It-Iu] / It] × 100 The upper limit of the X-ray crystallinity of the type II cellulose fiber of the present invention is
Not limited. Generally, the cellulose concentration is 3 to
The X-ray crystallinity of the cellulose fibers obtained by spinning 20% by weight of dope does not exceed 60%. Traditional
Type II cellulose fibers such as strong rayon, cupraammonium rayon, organic solvent spun fiber using NMMO as a solvent for cellulose, etc., have a crystallinity of 40% or more, a dry strength of 2.0 g / d or more, and an elastic modulus of 200 g / Although there were fibers having d or more, Tmax of these conventional type II cellulose fibers was less than 258 ° C, and the fibrillation resistance was not satisfactory.

The X-ray orientation degree (fc) of the type II cellulose fiber according to the present invention is 80% or more and less than 90%. Type II cellulose fibers having an X-ray orientation degree (fc) of less than 80% have good fibril resistance, but have low mechanical properties such as strength and elastic modulus. For example, a hollow fiber for artificial kidney, which is obtained by extruding a stock solution for cupra ammonium rayon into an 11 wt% NaOH aqueous solution at a low draft, coagulating it, and scouring and drying without stretching, has Tmax of 261 ° C. and an X-ray crystallinity of 46%.
However, the X-ray orientation degree was 79% and less than 80%, the dry strength was 1.2 g / d, and the elastic modulus was 43 g / d. On the other hand, X
Type II cellulose fibers having a degree of linear orientation (fc) of 90% or more have higher mechanical properties such as strength and elastic modulus and become fibers, but have poor fibrillation resistance even when the Tmax of the fibers is 258 ° C or higher. Only fiber can be obtained.

Here, the X-ray orientation degree (fc) is a value obtained by a transmission method. Set the scintillation counter (10
1) Fix at 2θ = 20.1 °, which corresponds to the diffraction angle of the plane, rotate the fiber bundle perpendicular to the incident X-ray, and set the azimuth angle ψ
The diffracted X-ray intensity of E. Ott, M .; Spurl
in edition “Cellulose and Cellulo
se Derivatives "2nd. ed. , Vo
l. II, Interscience publicize
It is calculated by the following formula described on page 1 of rs, New York (1954). Where ψ _1/2 is
It is a full width at half maximum represented by an azimuth angle (degrees).

Fc = {1- (ψ _1/2 / 180)} The type II cellulose fiber of the present invention has a degree of polymerization of 100 or more and 1 or more.
It is less than 300. Cellulose fibers having a degree of polymerization of less than 100 have extremely low mechanical strength. Degree of polymerization is 130
When it exceeds 0, it is difficult to stably spin the cellulose fibers due to a rapid increase in the viscosity of the cellulose solution during the fiber production, a decrease in the stability of the solution, and the like. here,
For the degree of polymerization, the [η] of the cellulose / cadoxene solution was determined, and the value obtained according to Euro. , Polym. , J. et al. , 1, 1 (196
6), Brown, Wikstrom
The viscosity average molecular weight Mw obtained by substituting it into the viscosity formula of wn, Wikstrom) was divided by 162 to obtain the viscosity average polymerization degree.

[Η] = 3.85 × 10 ^-2 Mw ^{0.76 In} the artificial cellulose fiber of the present invention, arbitrary conditions can be selected with respect to the fineness, the number of filaments and the cross-sectional shape of the filament. As a cellulose fiber material for clothing,
When 25 to 1000 denier fibers are used as long-fiber yarn, it is generally 10 to 500 denier yarn composed of 10 to 100 filaments.

The regenerated cellulose fiber of the present invention can be produced by the following method using any cellulose raw material. The natural cellulose raw material has a degree of polymerization of 100 to
Wood pulp, cotton linter, etc. in the range of 1300 can be used. Cellulose raw material has a cellulose concentration of 3w
A spinning dope of t% to 15% by weight (sometimes referred to as a stock solution) is prepared and extruded into an alkaline coagulation bath or coagulation / regeneration bath, and the extruded filament is hardly drafted or has a relatively small draft, preferably 3 or less. It can be prepared by winding with a suitable winding means while applying the draft. The coagulation liquid contains 0.
5 wt% to 15 wt% NaOH, preferably 1 to 5 wt%
An aqueous solution is used and the bath temperature is preferably not lower than the freezing temperature of the NaOH aqueous solution having a predetermined concentration and not higher than 50 ° C. The stock solution for spinning can be prepared by a viscose method, a cuprammonium method, a dissolution method using a suitable cellulose-soluble solvent such as N-methylmorpholine.

As an example, the method for preparing the fiber of the present invention by the copper ammonia method will be described. First, a purified cotton linter is dissolved in a copper ammonia solution, filtered and defoamed to prepare a spinning dope. The concentration of cellulose in the stock solution is a problem to be determined depending on the degree of polymerization of cellulose, but from the economical viewpoint, it is preferably 3 wt% or more. 0.05m of this stock solution
It is discharged into the coagulating liquid from a spinning nozzle having an orifice of mφ to 0.5 mmφ. The selection of the orifice diameter is determined by the single yarn denier of the fiber obtained and the cellulose concentration and draft of the spinning dope. The draft is 1-3. The coagulating liquid contains 0.5 wt% to 15 wt% of NaOH.
Spin using an aqueous solution while maintaining the bath temperature at 50 ° C or lower. The spinning method is not particularly limited, but it is selected and used according to the spinning speed, equipment cost, etc., such as the general horizontal static bath, the flow bath spinning method of the straight tube used in the high-speed spinning of viscose rayon filament. be able to. However,
The down-flow tension spinning method used in the production of cupra ammonium rayon filaments is difficult to apply because the coagulation is faster than that of cupra ammonium rayon type. The coagulated yarn is scoured without tension or subjected to stretching up to 1.5 times and then scoured and dried. Drying may be either tension-free or constant length.

The present invention is described below with reference to examples, but the present invention is not limited thereto.

[0018]

EXAMPLES In the examples, the mechanical properties of fibers and the degree of fibrillation were measured and evaluated as follows. (1) Measurement of Physical Properties of Fiber Structure The X-ray crystallinity, the X-ray orientation (fc), and the maximum temperature of tan δ in dynamic viscoelasticity of 200 ° C. or higher were measured by the methods described above. (2) Measurement of degree of polymerization of cellulose fiber and cellulose raw material It was calculated by the viscosity method described above. (3) Measurement of mechanical properties It was measured according to JIS L 1013. (4) Measurement and evaluation of degree of fibrillation 1) Fibrillation treatment About 0.5 g of each fiber sample was treated at 70 ° C. and 3 wt% sulfuric acid aqueous solution 3
After immersing in 00 g for 30 minutes, it was washed with ion-exchanged water, and the fiber sample was treated with 300 ml of ion-exchanged water at a temperature of 70
Home mixer (power consumption 260W,
It was stirred in a volume of 1200 ml) for 5 minutes.

2) Measurement and Evaluation of Degree of Fibrillation The state of rupture of the fiber in a slurry state was observed under an optical microscope with a magnifying power of 200, and the result of this observation was based on the following state of rupture of the fiber. The evaluation was made by illuminating and the evaluation points were assigned. Each sample was tested three times, and the average value was used as the degree of fibrillation. Fibers having a degree of fibrillation of 90 or more do not cause the problem of fibrillation during processing, washing or wearing.

Fiber breakage evaluation score Fibers in which no breakage is observed 100 Number of fibrils generated per single yarn length 1 to 280 Number of fibrils generated per single yarn length 4 to 650 Fibrils per single yarn length Number of generation 10 or more 20 Broken fiber in which the original diameter is not recognized 0 Example 1 Aqueous ammonia and basic copper sulfate were mixed to prepare a copper ammonia solution. A predetermined amount of purified cotton linter was added to this solution, and 10% by weight of NaOH aqueous solution was gradually added and stirred to dissolve cellulose to a cellulose concentration of 10%.
A homogenous solution of wt% was obtained. The solution was filtered through a filter layer in which two 300-mesh metal nets and two polyamide nonwoven fabrics were stacked, and then depressurized and defoamed to prepare a spinning dope. Using a extruder equipped with a gear pump, this dope was discharged from a spinning nozzle having 100 orifices with a hole diameter of 0.065 mmφ opened into a coagulating liquid bath (25 ° C.) of a 1 wt% to 30 wt% NaOH aqueous solution at 5 ml / min. Extruded. After coagulating while applying a draft of 10 times under the condition that the immersion length of the coagulating liquid bath is 25 cm, it is continuously washed with water at room temperature, oiled and dried at a constant length on a hot roll at 120 ° C. for 15 m. It is wound around a paper core under the condition of / min, 330d
/ 100f multifilament yarn was prepared. Table 1 shows the measurement results of the degree of polymerization, various physical properties of the fiber, the degree of fibrillation, and the mechanical properties of each of the obtained cellulose fibers. For reference, commercially available type II cellulose fiber, regular viscose rayon filament, cupra ammonium rayon filament, "TENCEL"
And Tmax of polynosic rayon, X-ray crystallinity,
Table 2 shows the degree of X-ray orientation, the degree of polymerization, the degree of fibrillation, and the mechanical properties.

As is clear from Table 1, Example 1 (N
o. Samples 1 to 4 having a Tmax of 258 ° C. or higher and an X-ray orientation degree of less than 90 have a fibrillation degree of 95 points or more, and have excellent fibril resistance and mechanical properties. The physical properties, particularly the wet strength and the wet elastic modulus, are remarkably improved as compared with general-purpose viscose rayon. Referring to Tables 1 and 2, Tm of type II cellulose fiber
It is clear that ax is critical to fibril resistance. With the exception of regular viscose rayon filament, cupra ammonium rayon filament, organic solvent spun fiber of NMMO type solvent "TENCEL",
Although polynosic rayon has excellent mechanical properties, it easily fibrillates at Tmax of 244 ° C. or less and is inferior in fibrillation resistance. Example 2 Using an extruder equipped with a gear pump, the dope prepared according to the method of Example 1 had a hole diameter of 0.065 mmφ,
5% by weight through three kinds of spinning nozzles each having 100 holes different from 0.080 mmφ and 0.131 mmφ
Discharge rate of 5m into a 25 ° C coagulation bath consisting of an aqueous NaOH solution
The filament yarn was wound at an extrusion take-up speed of 15 m / min at 1 / min. The draft in each spinning is 1, 1.5 and 4, respectively, and the immersion length of the coagulating liquid at 25 ° C is 25 cm.
After coagulating under the conditions described above, wash with water at room temperature, apply an oil agent, and rotate at a surface speed of 10 m / min.
Was dried for a fixed length on a hot roll of No. 3 to prepare three types of multifilament yarns (No. 7, 8 and 9 in descending order of draft) having different draft conditions during spinning. The degree of polymerization of the obtained fiber was 816 to 830. Table 3 shows the physical properties and performance evaluation values of the cellulose fiber obtained in this example.

Sample No. Regarding the fibers of draft 1 to 1.5 of 7 to 8, all of Tmax, X-ray crystallinity, X-ray orientation, and degree of polymerization are within the scope of the present invention, and the degree of fibrillation is 95 or more. Excellent fibril resistance,
It is a type II cellulosic fiber that has significantly better mechanical properties than viscose rayon. Sample No. The fiber No. 9 has high mechanical performance, but the degree of fibrillation is 62, and the fibril resistance is extremely poor. Sample No. Fiber No. 9 exhibits excellent mechanical properties due to its high draft, but shows poor fibril resistance.

[0023]

The present invention has high X-ray crystallinity and T
It is an artificial cellulose fiber having a high max, that is, a high density in an amorphous part. Type II cellulose fiber with high X-ray crystallinity and high wet mechanical strength typified by strength and elastic modulus, and with high Tmax and high density in the amorphous part, excellent in fibril resistance and suitable for outerwear applications Can be obtained.

[0024]

[Table 1]

[0025]

[Table 2]

[0026]

[Table 3]

Claims (1)

[Claims] 1. A viscosity average polymerization in which the X-ray crystallinity is 40% or more, the X-ray orientation degree is 80% or more and less than 90%, and the maximum temperature of tan δ in dynamic viscoelasticity of 200 ° C. or more is 258 ° C. or more. Cellulose II with a degree of 100 or more and less than 1300
Cellulose fibers with mold type crystallinity.