JPS641565B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel composite fiber with excellent mechanical properties. More specifically, it consists of a cellulose derivative and an acrylonitrile polymer,
This is a novel composite fiber with a high degree of crystal orientation, which is made by phase-separating and dispersing cellulose derivatives into fine fibers, and its purpose is to improve not only mechanical properties but also tensile strength. The object of the present invention is to provide a novel acrylic composite fiber that is particularly excellent in initial modulus, hook strength, and elongation. In general, acrylic fibers have a texture similar to wool, and have good abrasion resistance, high photostability, and excellent dyeability, making them extremely useful for clothing, industrial materials, and semi-industrial materials. Although it is a fiber, it is not only used for industrial materials, but also for quasi-industrial materials or clothing applications, because its tensile strength and elongation are insufficient, but its hook strength and elongation are insufficient.
It has the disadvantages that it reduces spinnability, causes cracking when made into textile products such as woven and knitted fabrics, and provides textile products with poor elasticity due to the low initial modulus. In the past, attempts have been made to improve this drawback by applying to acrylic fibers a means of producing fibers with a high draw ratio and high degree of orientation, which is usually useful in the production of synthetic fibers, but such means have not been successful. Although it is recognized that the initial modulus of the fibers obtained by this method is improved, it does not lead to a significant improvement in hook strength and elongation, and furthermore, due to the high draw ratio and high orientation fiber formation, a tendency to fibrillation occurs. This resulted in new drawbacks such as the generation of fuzz and a decrease in abrasion resistance. In view of these drawbacks of acrylic fibers, the present inventors conducted extensive studies on composite fiber systems consisting of a combination of an acrylonitrile polymer and various polymers, and found that acrylonitrile polymers other than the acrylonitrile polymer that constitute the composite fibers were used. By using a cellulose derivative as a component and having a specific dispersion structure and a specific fiber microstructure, the excellent characteristics of conventional acrylic fibers are retained, while their drawbacks are greatly improved. Complete a new composite fiber that has excellent mechanical properties, especially initial modulus and hook strength and elongation, and also has superior thermal stability compared to conventional acrylic fibers. It came to this. That is, the present invention provides fibers that are substantially composed of a cellulose derivative and an acrylonitrile-based polymer, in which the cellulose derivative is phase-separated and dispersed in the form of fine fibers, and which has an acrylonitrile content measured by wide-angle X-rays. The crystal orientation angle of the system polymer part is 18°~
63°, and the ratio of the crystal orientation angle between the cellulose derivative part and the acrylonitrile polymer satisfies the following formula (1).
It is a composite fiber with excellent hooking strength and elongation, and its characteristics include the cellulose derivative component that makes up the composite fiber,
The highly oriented acrylonitrile polymer, which is arranged in a phase-separated form in the form of fine fibers, retains the characteristics of acrylic fibers, while also being a filler with highly oriented cellulose derivatives and a matrix. By creating a unique microstructure between the acrylonitrile polymers, we are able to express the reinforcing effect of the filler as a composite fiber, resulting in a fiber with excellent mechanical properties, especially initial modulus and hook strength and elongation. It has a fine structure and improved physical properties that are not found in conventionally known fibers obtained by simply mixing and molding a cellulose derivative and an acrylonitrile polymer. That is, it has been known that a dope in which a cellulose derivative and an acrylonitrile polymer are dissolved in a solvent and that such a dope undergoes phase separation, and that the cellulose derivative phase separates into the acrylonitrile polymer from such a dope. Dispersible fibers are also already known. For example, Kates, Journal of Polymer Science, Volume 20, 155.
Page (1966) (J.Polymer.Sci., 20 , 155 (1966)),
Japanese Patent Publication No. 31-968 describes the use of N,N-dimethyl-formamide, and Japanese Patent Publication No. 37-2986 describes the use of concentrated aqueous solutions of inorganic salts.
-14029 publication describes dimethyl sulfoxide,
Both documents describe that fibers can be produced from a dope in which cellulose acetate and an acrylonitrile polymer are dissolved. Furthermore, Japanese Patent Publication No. 33-4023 discloses a fiber comprising cyanoethylcellulose as a cellulose derivative and an acrylonitrile polymer. However, although the fibers obtained by such known techniques are effective in making them dyeable with cellulose dyes or improving their hygroscopicity, they do not have the mechanical properties that were the main objective of the present inventors. What is the fact and idea that fibers with excellent initial modulus and hook strength and elongation can only be achieved by creating a specific dispersed conjugate fiber structure and a specific microstructure with cellulose derivatives and acrylonitrile polymers? It is understood that the fibers of the present invention are fundamentally and essentially completely different from conventionally known fibers made of cellulose derivatives and acrylonitrile polymers, not only in terms of technical concept but also in the fibers themselves. must be done. In fact, fibers made using such known technology are
It goes without saying that the fibers of the present invention do not satisfy any of the microstructural requirements, and in terms of thermal stability, they do not improve the thermal stability of conventional acrylic fibers, and in some cases may actually deteriorate. It was something that caused. In the fiber of the present invention which has excellent mechanical properties,
In order to combine the excellent properties of conventional acrylic fibers, such as good abrasion resistance, high photostability, and excellent dyeability, measurements are performed using wide-angle X-ray diffraction, which will be explained in detail below. Not only is it necessary that the crystal orientation angle is 18° to 63°, but it is also important that the ratio of the crystal orientation angles of the cellulose derivative part and the acrylonitrile polymer part satisfies formula (1). be. α _{Cell Der} /α _PAN ≦1 (2) However, in formula (1), α _{Cell Der} is the crystal orientation angle (°) of the cellulose derivative part, and α _PAN is the crystal orientation angle (°) of the acrylonitrile polymer part. show. The present inventors, based on the above-mentioned publicly known materials,
Although additional trials were carried out, we were unable to obtain sufficient fibers, and we proceeded with further investigation to get closer to the present invention.
When the crystal orientation angle of the obtained fibers was measured by wide-angle X-ray diffraction, it was found that the crystal orientation angle in the acrylonitrile polymer part was sufficiently small and showed high orientation, but the crystal orientation angle in the cellulose derivative part was was extremely large and its crystal orientation was extremely low. In other words, in order to exhibit the properties of conventional acrylic fibers, it is necessary that the crystal orientation of the acrylonitrile polymer portion is sufficiently achieved, and for this purpose It is important that the crystal orientation angle is in the range of 18° to 63°. In addition to the above-mentioned properties, in order to improve mechanical properties and thermal stability, acrylonitrile polymer is added to the cellulose derivative part, which is dispersed in the form of fine fibers, to exert a reinforcing effect. It is important that the crystal orientation is higher than that of the other parts. That is, since the cellulose derivative portion, which is the reinforcing fiber, is highly crystal oriented, the stress applied to the acrylonitrile polymer portion when subjected to stress is alleviated, and the amount of deformation is reduced. Therefore,
It is necessary that the crystal orientation of the cellulose derivative portion is at least higher than that of the acrylonitrile polymer, and it is important that the crystal orientation angle measured by X-ray diffraction is smaller, satisfying formula (1). That is important. Fibers that do not satisfy formula (1) cannot have mechanical properties, particularly high initial modulus, hook strength and elongation, and thermal stability. For example, comparative example 3
As will be explained in detail later, the crystal orientation angle of the acrylonitrile polymer portion of the fiber made of cyanoethyl cellulose and acrylonitrile polymer obtained by a conventionally known method is 29.6°, which is highly oriented. Regardless, the crystal orientation angle of the cyanoethyl cellulose part was extremely large at 48.0°, and the orientation was extremely low, and the ratio of the crystal orientation angle of the cyanoethyl cellulose part to the acrylonitrile polymer part was 1.62. On the other hand, in the fiber of the present invention, the crystal orientation angle of the acrylonitrile polymer portion is sufficiently small and has high orientation, and the crystal orientation angle of the cellulose derivative portion is even smaller than the crystal orientation angle of the acrylonitrile polymer. It shows higher orientation,
The fibers were completely different from conventionally known fibers in the ratio of crystal orientation angles between the cellulose derivative portion and the acrylonitrile polymer portion. For example, the crystal orientation angle of the acrylonitrile polymer portion in the fiber of the present invention consisting of cyanoethylcellulose and acrylonitrile polymer obtained in Example 1 is
The crystal orientation angle of the cyanoethyl cellulose part was extremely small at 15.1°, which was similar to the acrylonitrile polymer part in conventionally known fibers in that it had a high orientation of 28.4°.
The ratio of crystal orientation angles between the cyanoethyl cellulose part and the acrylonitrile polymer part was 0.53. In this way, while conventionally known fibers are composed of an acrylonitrile polymer part that exhibits high crystal orientation and a cellulose derivative part that has low crystal orientation, the composite fiber of the present invention uses fine fibers as a filler. The crystal orientation of the cellulose derivative part, which is phase-separated and dispersed in a shape, exceeds the crystal orientation of the acrylonitrile polymer part as a matrix, and the formula (1)
As a result, for example, in the above example, the tensile strength and initial modulus of conventionally known fibers are
2.1 g/d and 41.4 g/d, and the hooking strength and elongation are 1.6 g/d and 5.7%, respectively, whereas in the above-mentioned fiber of the present invention, the tensile strength and initial modulus are 4.0 g/d and 59.5. g/d, hooking strength and elongation of 2.9 g/d and 13.7%, resulting in a significant improvement in mechanical properties, particularly initial modulus, hooking strength and elongation. Although the mechanism by which the reinforcing effect on the fiber microstructure that exhibits such a remarkable effect cannot be left out of the realm of speculation, it is at least possible that the stress applied in the direction of the fiber axis or in the direction perpendicular to the fiber axis acts as a filler in the matrix. This is thought to be due to concentration and relaxation in the fine fibrous filler of the cellulose derivative, which is expected to have higher orientation and superior strength and elongation properties and dimensional stability than the acrylonitrile polymer. On the other hand, fine fibers of cellulose derivatives as filler
If the filler exhibits only low orientation and is thought to be inferior in strength and elongation properties or dimensional stability, the filler may easily break or elongate during the stress extension, and the mechanical properties of the fiber may deteriorate. This is thought to cause a decrease in In the present invention, it is preferable that the cellulose derivative as the filler forming the composite fiber is dispersed in the form of fine fibers, and if it exists in the form of extremely coarse particles or non-uniform distribution, the composite effect will be A sufficient effect of improving mechanical properties was not observed, and as shown in the attached optical micrograph of the cross section of the fiber, it is preferable that the fiber be dispersed almost uniformly over the entire cross section, but this does not impair the effects of the present invention. To the extent possible, distributions such as concentric or eccentric sheath-core type, or concentrated arrangement inside the fiber side periphery are also permitted. Since it is impossible with current technology to directly extract the fine fibrous material made of cellulose derivatives distributed in composite fibers and measure and define its shape, indirect measurement using an optical or electron microscope is necessary. The diameter of the fine fibrous material is approximately 1/10 or less of the total composite fiber diameter, preferably 1 μ or less, as shown in the attached electron micrograph for understanding, although the shape cannot be clearly defined. It's good.
In addition, the ratio of the length and diameter of the fine fibrous material (length/diameter) is
It should be at least 20. The cellulose derivative useful for the fiber of the present invention preferably has a structure represented by the following formula, In the formula, R is acetyl, propioyl, butyryl, stearoyl, acid phthaloyl, alkyl having 1 to 5 carbon atoms, cyanomethyl, cyanoethyl, hydroxymethyl, hydroxyethyl, hydroxypropyl, carboxymethyl and its sodium salt, carboxyethyl and its sodium It represents a group selected from the group consisting of salt, sodium sulfate, and nitro, and 0 to 4 R's in the two cellulose units represented by formula (1) may be hydrogen. Specifically, cellulose acetate, methylcellulose, ethylcellulose, cyanoethylcellulose, methylcyanoethylcellulose, hydroxymethylcellulose, cyanoethylhydroxymethylcellulose, hydroxyethylcellulose, sodium carboxymethylcellulose, sodium carboxyethylcellulose, sodium methylcarboxymethylcellulose, sodium cyanoethylcarboxymethylcellulose, etc. Particularly preferred are cellulose acetate, cyanoethylcellulose, and methylcellulose, and commercially available ones may be used as they are, or those produced and purified by appropriate means may be used.
The average degree of substitution (DS) of anhydroglucose units in the cellulose derivative used in the fiber of the present invention may be 1.0 or more, preferably 1.5 to 3.0. The average degree of polymerization (DP) of anhydroglucose units is usually 50 to 700, although it varies somewhat depending on the type of cellulose derivative. It goes without saying that one type of these cellulose derivatives may be used in the fiber of the present invention;
It may be used as a mixture of more than one species. The acrylonitrile polymer used in the fiber of the present invention is an acrylonitrile polymer or an acrylonitrile copolymer obtained by a conventional polymerization method of 40 mol% or more of acrylonitrile and other copolymerizable vinyl monomers. Any type of copolymer may be used, but copolymers are preferred from the viewpoint of the dyeability of the resulting fibers, and those containing 85 mol% or more of acrylonitrile are particularly preferred. Examples of specifically used comonomers include acrylamide, methacrylamide, N-methylacrylamide, and N-methylacrylamide.
-Ethyl methacrylamide, maleimide, allyl alcohol, methacrylic alcohol, β-hydroxyethyl methacrylate, methallylamine, β
-aminoethyl methacrylate, acrylic acid, methacrylic acid, itaconic acid, methyl acrylate,
Methyl methacrylate, ethyl methacrylate,
Examples include, but are not limited to, α-methylacrylonitrile, α-cyanoacrylonitrile, vinyl acetate, vinyl chloride, vinylidene chloride, and styrene. The fibers of the present invention can be manufactured specifically and with good reproducibility through the Examples described later, which can be easily replicated by those skilled in the art. Of course, these examples are merely illustrative of some of the production examples of the present invention, and generally, production is carried out with reference to the examples described later and with the following points in mind. be able to. The composition ratio of the cellulose derivative and the acrylonitrile polymer in the fiber of the present invention is not particularly limited, and in order to produce the fiber, predetermined amounts of the above-mentioned cellulose derivative and acrylonitrile polymer are respectively dissolved. The dope may be prepared by dissolving it in a suitable solvent, preferably concentrated nitric acid, and then fabricated into fibers by conventional wet spinning or semi-dry/semi-wet spinning. It is important that the dope used in the present invention exhibits flow birefringence or optical anisotropy. Flow birefringence means that when a small amount of dope is placed between a slide glass and a cover glass and observed under a microscope under orthogonal polarized light and dark field in a stationary state, no light is transmitted through it, and when a finger pressure is applied to the cover glass, etc. Optical anisotropy refers to the optical property of transmitting light when similar observation is made in a flowing state with force applied to it, that is, a shearing force applied. These dopes have the property of transmitting light even under visual field, and these dopes can be observed and determined by the above method, and those skilled in the art can easily determine their optical isotropy. It can be distinguished from the dope shown. A dope exhibiting such flow birefringence or optical anisotropy can be obtained by dissolving the cellulose derivative and the acrylonitrile polymer in a solvent that simultaneously dissolves the cellulose derivative and the acrylonitrile polymer. The solvent used at this time may be any of an inorganic acid type, an inorganic salt aqueous solution type, or an organic solvent type as long as it can substantially dissolve the above-mentioned cellulose derivative and acrylonitrile polymer. The solvent may be a single solvent or a mixed solvent of two or more, and additives such as inorganic salts or organic acid salts, metal oxides, etc. may be added for the purpose of adjusting solubility. Specific examples include nitric acid, hydrochloric acid, sulfuric acid, phosphoric acid, fluorosulfuric acid,
Chlorosulfuric acid, and one or more solutions of these to which are added inorganic salts such as sodium nitrate, calcium nitrate, sodium nitrate, sodium phosphate, ammonium phosphate, etc., zinc chloride, sodium thiocyanate, potassium thiocyanate, So-called rhodan salts such as calcium thiocyanate, aqueous solutions of inorganic salts such as magnesium chloride and calcium chloride, N,N-dimethylformamide, N,N-dimethylacetamide, N-methyl-2-pyrrolidone, N,N,N', N'-tetramethylurea, N,
Examples include so-called amide solvents such as N'-dimethylimidazolidinone, and one or more mixed solvents such as dimethyl sulfoxide, acetonitrile, ethylene carbonate, ethylene cyanohydrin, and γ-butyrolactone. Further, examples of additives added for the purpose of adjusting solubility include calcium chloride, magnesium chloride, lithium chloride, sodium acetate, calcium oxide, titanium oxide, and the like. To prepare a dope from such a cellulose derivative, an acrylonitrile polymer, and a solvent, the above-mentioned cellulose derivative, acrylonitrile polymer, and a suitable solvent are stirred together at room temperature or with heating or cooling as necessary. Alternatively, it can be prepared by mixing separate solutions of the cellulose derivative and the acrylonitrile polymer. In order to obtain a dope composition exhibiting polarity, the type and properties of the cellulose derivative, such as the average degree of substitution (DS), average degree of polymerization (DP), and solubility, or the type and degree of polymerization of the acrylonitrile polymer, must be selected. For example, for the same type of cellulose derivative, the higher the average degree of substitution (DS) and average degree of polymerization (DP), the lower the dope concentration, and the higher the average degree of polymerization (DP). This occurs in the low doping concentration range by lowering the temperature. Although the dope concentration at which flow birefringence or optical anisotropy occurs varies depending on the composition ratio of the cellulose derivative and the acrylonitrile polymer, flow birefringence or optical anisotropy occurs over almost the entire composition ratio. The idea is recognized. Due to various factors, it is not possible to definitively indicate the composition exhibiting flow birefringence or optical anisotropy based on the dope concentration, but for example, if the solvent is an aqueous inorganic acid solution such as an aqueous nitric acid solution, it is approximately % or more, if the solvent is an amide solvent such as N-methyl-2-pyrrolidone or dimethylformamide, and the cellulose derivative is cellulose acetate, the concentration is about 25% by weight or more, and if the cellulose derivative is cellulose acetate, it is about 25% by weight or more, and if the cellulose derivative is cellulose acetate, it is about 25% by weight or more.
The dope concentration may be 20% by weight or more, or about 15% by weight or more when the solvent is dimethyl sulfoxide and the cellulose derivative is cyanoethylcellulose.
Further, when the solvent is a 65% by weight zinc chloride aqueous solution and the cellulose derivative is cyanoethyl cellulose, the dope concentration may be about 10% by weight or more. The filament coagulated from the dope through a spinneret can be made into a final fiber through the steps of water washing, stretching, drying, heat setting, etc., which are common in ordinary fiber manufacturing processes. The fiber of the present invention thus obtained has the formula (1)
It is a fiber with excellent mechanical properties, especially initial modulus and hook strength and elongation, which is exhibited by a special microstructure that satisfies hand,
Furthermore, it has excellent thermal stability, and thus is a truly novel composite fiber that cannot be obtained with conventional acrylic fibers or known composite fibers. The fiber of the present invention may be used in any form, usually in the form of a staple fiber, a tow, a monofilament, or a multifilament, and in any case,
Acrylic fibers have traditionally been offered because they have the characteristics of wool-like texture, good abrasion resistance, high photostability, and excellent dyeability. In the clothing field, it is of course used as an excellent textile product that is flexible and elastic due to its high initial modulus, hooking strength and elongation, and is resistant to key tearing, etc., but also for tents, car covers, dryer canvas, etc. It is especially effective when used in semi-industrial materials or industrial material application fields. Below, methods for measuring the main parameters used to identify the fibers and measure the physical properties of the present invention will be described in detail. <Dope viscosity measurement method> Measurement was performed using a BH type rotational viscometer manufactured by Tokyo Keiki Co., Ltd., rotor No. 6 at a rotor rotation speed of 2 rpm. <Fiber property measurement method> Denier: Torsion balance MODELTI manufactured by Eiko Sangyo Co., Ltd.
Using this method, the single yarn denier was determined from 10 single yarns of 90 mm. Tensile strength and elongation and modulus Using a UTM-20 tensile tester manufactured by Toyo Baldwin Co., Ltd., as a single yarn with a yarn length of 20 mm, the head speed was 20 mm/min. The chart speed was 200 mm/min.
The SS curve was measured under the following conditions and determined by a conventional method. <Thermoform stability> Load is 0.1 on yarn length 180mm, 5000 denier tow
A weight of 500 g was applied so as to give g/d, and the elongation rate was measured after 10 minutes in a boiling water bath. <Measurement method of crystal orientation angle by wide-angle X-ray diffraction The crystal orientation angle of fibers can be measured by a conventional method using a photograph or a counter.
For example, according to the counter method, an X-ray generator manufactured by Rigaku Corporation (RU-Z00PL), a fiber measuring device (FS-
3), carried out using a goniometer (SG-9R) and a scintillation counter. For measurement, CuK〓 (λ = 1.54
Å). The fiber of the present invention is characterized by having strong reflection on the equator line due to the cellulose derivative and acrylonitrile fiber. For example, reflection around 2θ=10° is caused by the cellulose derivative, and reflection around 2θ=17° is caused by the acrylonitrile polymer. The above two reflections are used to measure the orientation angle, and the exact value of 2θ of the reflection used to measure the crystal orientation is determined from the diffraction intensity curve in the equatorial direction of each sample. The crystal orientation angles of the cellulose derivative portion and the acrylonitrile polymer portion are measured by a conventional method using reflection having a 2θ characteristic to each of them. The X-ray generator is operated at 32 KV and 100 mA, and the fiber sample is attached to the fiber measuring device so that the single yarns are parallel to each other. It is appropriate that the thickness of the sample be approximately 2 mm. Set the goniometer to the 2θ value determined by preliminary experiments. X-rays are incident perpendicularly to the fiber axes arranged in parallel (beam perpendicular transmission method). Rotate the sample in a plane perpendicular to the beam, azimuth = -
Scan the range from 90° to +90° and record the diffraction intensity on recording paper. The scanning speed at this time is = 4°/min, chart speed 1cm/min, time constant
5sec, collimator 2mmφ, receiving pinhole is square 2mm on each side. Furthermore, the diffraction intensity can be measured without continuous scanning.
It may also be measured by step scanning. To determine the crystal orientation angle (crystal orientation angle of the cellulose derivative part; α _{Cell Der} , crystal orientation angle of the acrylonitrile polymer part; α _PAN ) from the obtained diffraction intensity curve, use the diffraction obtained at = ±90°. Take the average value of the intensity and draw a horizontal line to use it as the background.
Drop a perpendicular line from the top of the peak to the base line and find the midpoint of its height. Draw a horizontal line through the midpoint. Measure the distance between the intersection of this horizontal line and the diffraction intensity curve,
The value obtained by converting this value into an angle (°) is defined as the orientation angle. From the crystal orientation angle of the cellulose derivative part (α _{Cell Der} ) and the crystal orientation angle of the acrylonitrile polymer part (α _PAN ) obtained in this way, the ratio of the degree of crystal orientation (α _{Cell Der} /α _PAN ) is calculated. I asked for it. The present invention will be explained in more detail below with reference to Examples, in which % means % by weight unless otherwise specified. Example 1 and Comparative Example 1 Average degree of polymerization (DP) 316, average degree of substitution (DS)
2.60 cyanoethylcellulose 40.3gr and acrylonitrile/methyl acrylate = 92/8 (mol%)
Acrylonitrile copolymer with η _ioh = 1.24 consisting of
362.7gr was added to 1500ml of 67% nitric acid aqueous solution and dissolved with stirring to create a dope with a concentration of 16%. The viscosity of this dope at 1.5℃ is 725 poise, and microscopic island-like phases have been separated.
By applying shearing force by shifting the slide glass and cover glass under orthogonal polarized dark field, this island-like phase was elongated into a long and thin structure, and it was observed that it exhibited fluid birefringence by transmitting light. It was done. This dope was transferred to a dope tank equipped with a cooling jacket, and after vacuum defoaming while maintaining the dope temperature around 0°C, it was spun at 4.27ml/min, 8.50mm using a spinneret with a hole diameter of 0.08mmφ and 100 holes. The yarn was discharged into a coagulation bath consisting of a 35% nitric acid aqueous solution with a bath length of 1 m at a linear discharge speed of /min, then wound up at a speed of 4 m/min, then washed through a 5 m water bath, and then boiled at a boiling point of 2.5 m. A fiber was obtained by stretching 9.9 times in a water bath. The fibers thus obtained were then dried in a relaxed state with hot air at 70°C, and then placed in pressurized steam at 105°C for 4 hours.
Figure 1 shows a cross-sectional photograph taken with an electron microscope in a direction perpendicular to the fiber axis of the fibers that were left for a minute and underwent relaxation steam treatment. Figure 2 shows a side view of the fibers taken with an optical microscope. The angle ratio and fiber physical properties are shown in Table 1. For comparative reference, Table 1 shows fibers made of only the same acrylonitrile copolymer used in Example 1 and obtained by the same spinning method and post-treatment as in Example 1.

[Table] The properties are also listed as Comparative Example 1. As is clear from FIGS. 1 and 2, the fiber of the present invention forms a composite fiber in which a cellulose derivative (cyanoethyl cellulose) is phase-separated and dispersed into fine fibers, and the cyanoethyl cellulose part and the acrylonitrile-based The degree of crystal orientation of the copolymer was 0.81 as shown in Table 1. This fiber has extremely superior initial modulus and hook strength and elongation compared to conventional acrylic fibers (Comparative Example 1), and is also superior in thermal stability. It was confirmed that the fiber had both stability and stability. Example 2 Average degree of polymerization (DP) 330, average degree of substitution (DS)
70% of 1000ml of 16.6gr of cyanoethyl cellulose of 2.62% and 315.3gr of acrylonitrile copolymer of η _ioh = 1.32 consisting of acrylonitrile/acrylamide/methyl acrylate = 90/5.5/4.5 (mol%)
It was added to an aqueous nitric acid solution and dissolved with stirring to create a dope with a concentration of 19%. The viscosity of this dope at 0℃ is
2150 poise, and the microscopic island-like phase was separated by microscopic observation. Under orthogonal polarized dark field, by pressing the cover glass with your fingers and shifting it, you could see that only this island-like phase could be seen in the fluid state. It was observed that it transmits light and exhibits flow birefringence. This dope was transferred to a dope tank equipped with a cooling jacket, and after vacuum defoaming while maintaining the dope temperature around 0°C, it was spun at 4.27 cc/min, 2.78 m/min using a spinneret with a hole diameter of 0.14 mmφ and 100 holes. With discharge linear velocity of min, bath length 1m across 5mm space, 38%
Discharged into a coagulation bath consisting of an aqueous nitric acid solution, then 4
After winding with a roll at a speed of m/min and washing the yarn through a 5 m water bath, it was placed in a 2.5 m boiling water bath.
Stretched fibers were obtained by stretching 11.5 times. The obtained drawn fibers were then dried under the same conditions as in Example 1.
A steam treatment was performed to obtain the final fiber. The crystal orientation angles of the cyanoethyl cellulose part and the acrylonitrile copolymer part by X-ray diffraction of this fiber were 15.1° and 28.4°, respectively, indicating that both parts had high orientation, and the crystal orientation angle ratio was 0.53. It was hot. This fiber and Comparative Example 2, which will be described later for comparative reference.
Table 2 shows the physical properties and crystal orientation angle ratio of the fibers obtained in Example 2 and 3. It is understood that it is an extremely excellent composite fiber, demonstrating outstanding initial modulus, hook strength and elongation, and thermal stability, which are achieved by the high orientation of both cyanoethyl cellulose and acrylonitrile polymers. Ta.

[Table] Figure 3 shows a cross-sectional photograph of this fiber taken with an electron microscope in a direction perpendicular to the fiber axis. Comparative Example 2 The same cyanoethyl cellulose and acrylonitrile copolymer as in Example 2 was used at a composition ratio of 20/80.
(weight ratio), the dope was dissolved in the same 70% nitric acid aqueous solution used in Example 2 so that the dope concentration was 13%, and the same spinning method and steaming treatment as in Example 2 were carried out. A composite fiber was obtained. The crystal orientation angle ratio and fiber physical properties of this fiber are also listed in Table 2 above, and unlike the fiber of the present invention, the crystal orientation angle ratio is 1.36, especially because of the low orientation of the cyanoethyl cellulose part. It was found that the initial modulus, hook strength and elongation properties were extremely poor, and the tensile strength and elongation properties were also inferior to the fibers of the present invention. It should be noted that microscopic observation of the dope used to produce the fibers of this comparative example revealed that fine island-like phases were separated; Even when a shearing force was applied to the sample, no light transmission was observed, and the sample did not exhibit any flow birefringence or optical anisotropy. Comparative Example 3 The same cyanoethyl cellulose and acrylonitrile copolymer as in Example 2, 81 gr and
324 g was added to 1620 g of dimethyl sulfoxide at room temperature and dissolved with stirring to prepare a dope with a concentration of 20%. The viscosity of this dope at 27° C. was 400 poise, and observation under a polarized dark field microscope confirmed that it was an optically isotropic dope. This dope was spun and heated in the same manner as in Example 2, except that the bath temperature was 50°C, the bath concentration was 50% dimethyl sulfoxide aqueous solution, and the stretching ratio was 7.5 times, to obtain fibers. The physical properties of this fiber and the crystal orientation angle ratio of the cyanoethyl cellulose part and the acrylonitrile copolymer part as determined by X-ray diffraction are as shown in Table 2 above, and the crystal orientation of the acrylonitrile polymer part is almost sufficiently high. However, the crystal orientation of the cyanoethylcellulose portion was low, and the mechanical properties and thermal stability of the fiber were significantly lower than those of the fiber of the present invention. Example 3 Average degree of polymerization (DP) 180, average degree of substitution (DS)
35.3 gr of cellulose acetate of 2.50 and 317.3 gr of acrylonitrile copolymer consisting of acrylonitrile/acrylamide/methyl acrylate/sodium methallylsulfonate = 91.5/1.5/6.5/0.5 (mol%)
was dissolved in 750 ml of a 69% nitric acid aqueous solution to prepare a dope. This dope was confirmed to exhibit flow birefringence by microscopic observation under orthogonal polarized dark field. This dope is attached to a dope with a cooling jacket.
After transferring the dope to a tank and degassing it under vacuum while keeping the dope temperature around 0°C, it was spun into a 4 mm space using a spinneret with a hole diameter of 0.14 mmφ and 100 holes at a linear discharge speed of 3.37 cc/min and 2.19 m/min. The mixture was discharged into a coagulation bath consisting of a 33% nitric acid aqueous solution with a bath length of 1 m, and then treated in the same manner as in Example 1 to obtain fibers. The crystal orientation angles of the cellulose acetate portion and the acrylonitrile copolymer portion of this fiber were 36.8° and 37.6°, respectively, as shown in Table 3 along with the fiber physical properties, and the ratio thereof was 0.98. This fiber has excellent initial modulus, hook strength and elongation, and also has high tensile strength that cannot be obtained with conventional acrylic fibers, demonstrating how high the mechanical properties of the fiber of the present invention are. was.

【table】 [Brief explanation of drawings]

Figures 1 and 3 show Examples 1 and 2, respectively.
FIG. 2 is an electron micrograph (22000x and 400x) of the fiber of the present invention obtained in Example 1.
This is a side view photograph (22,000x) of the fiber obtained using an optical microscope.

Claims (1)

[Scope of Claims] 1. A substantially cellulose derivative formed by spinning a dope that is composed of a cellulose derivative, an acrylonitrile polymer, and a solvent that substantially simultaneously dissolves these, and exhibits fluid birefringence or optical anisotropy. and an acrylonitrile-based polymer, the cellulose derivative is phase-separated and dispersed into fine fibers, and the crystal orientation angle of the acrylonitrile-based polymer portion measured by wide-angle X-ray diffraction is 18 The ratio of the crystal orientation angle between the cellulose derivative part and the acrylonitrile polymer part is expressed by the following formula (1).
A new composite fiber that satisfies the following. α _{Cell Der} /α _PAN ≦1 (1) where α _{Cell Der} is the crystal orientation angle (°) of the cellulose derivative portion, and α _PAN is the crystal orientation angle (°) of the acrylonitrile polymer portion. 2. The composite fiber according to claim 1, wherein the cellulose derivative has a structure represented by the following formula (2). In formula (2), R is acetyl, propioyl, butyryl, stearoyl, acid phthaloyl, alkyl having 1 to 5 carbon atoms, cyanomethyl, cyanoethyl,
Hydroxymethyl, hydroxyethyl, hydroxypropyl, carboxymethyl and its sodium salt, carboxyethyl and its sodium salt,
It represents a group selected from the group of sodium sulfate and nitro, and 0 to 4 of R in the two cellulose units represented by formula (2) may be hydrogen. 3. The composite fiber according to claim 1, wherein the acrylonitrile polymer is an acrylonitrile polymer and/or an acrylonitrile copolymer containing 40 mol% or more of acrylonitrile.