JP2021105244A - High-performance fiber and dope used in manufacturing of the fiber - Google Patents

Abstract

To provide a fiber having high physical properties of tensile strength and tensile elastic modulus without using ultrahigh-molecular-weight polymers.SOLUTION: A fiber 11 of the present invention is a fiber formed of a vinyl polymer with an intrinsic viscosity of 1.3-5.0 dL/g and having a crystal orientation degree of 96.6-98% as measured by wide-angle x-ray diffraction. Moreover, preferably, its tensile strength is 0.7-2.5 GPa and its tensile elastic modulus is 15-40 GPa. The fiber can be manufactured by using a spinning solution prepared by dissolving a vinyl polymer with an intrinsic viscosity of 1.3-4.0dL/g in an ionic liquid.SELECTED DRAWING: Figure 1

Description

The present invention provides mechanically high-performance, high-strength, high-modulus fibers obtained from vinyl-based polymers such as acrylic-based polymers having a general molecular weight that can be industrially used instead of ultra-high molecular weight fibers. It relates to a spinning stock solution used in the production of fibers.

Acrylic fiber has features similar to wool, excellent elastic resilience, shrinkage resistance, chemical resistance, etc., and can be given various functions such as antibacterial, deodorant, static electricity, and heat generation. For this reason, it has been attracting attention as a functional fiber in recent years.

In addition, there are various uses, and physical properties with higher tensile strength and tensile elastic modulus of the fiber are required.

Acrylic fibers are generally prepared by dissolving polyacrylonitrile polymer powder using an organic solvent such as dimethylformamide (DMF), dimethylacetamide (DMAc), or dimethyl sulfoxide (DMSO), or an aqueous solution in which nitrate or an inorganic salt is dissolved. It is manufactured by making it into a spinning stock solution and molding it through steps such as spinning, stretching, and drying.

A wet spinning method or a dry wet spinning method is generally used for spinning, and the undiluted spinning solution discharged from the mold passes through the coagulating solution in the spinning bath to promote coagulation and gelation to form fibers. The coagulating liquid in the spinning bath is generally a mixture of the solvent and water used in the spinning stock solution, and is produced so that the production is stable and the fiber structure is uniform by adjusting the temperature and concentration.

However, with the conventional solvent-based method, it is not easy to obtain fibers having a uniform form due to rapid mutual diffusion at the boundary between the initial fibers immediately after exiting the nozzle and the coagulation bath, and the resulting coagulation formation. rice field. In particular, acrylic fibers used as materials are basically preferably voidless and have a dense fiber structure, but the conventional method has a drawback that voids are likely to be formed by rapid solidification. In addition, there are problems such as enormous cost for recovering a large amount of solvent and environmental pollution.

To solve this problem, Patent Document 1 reports a solution for mixing a polyacrylonitrile polymer (PAN) and an ionic liquid and performing melt spinning. Since this method melts and spins acrylic fibers, it does not use a large amount of solvent, so it is possible to reduce the environmental load. Has the problem of reduced physical properties and productivity as compared with the conventional wet and dry wet spinning methods.

In addition, Non-Patent Document 1 reports a polymerization of acrylonitrile and a dry-wet spinning method using an ionic liquid. This report also has a great merit in terms of reducing the environmental load because the use of organic solvent is suppressed as compared with the conventional wet spinning method. However, in terms of physical properties such as strength and elongation, performance superior to that of conventional industrial acrylic fibers has not been obtained.

Further, in Non-Patent Document 2, an ultra-high molecular weight polyacrylonitrile polymer having a molecular weight of 2.3 million is dissolved in DMF, extruded into a coagulation bath at -40 ° C by dry-wet spinning, and super-stretched to produce highly physical acrylic fibers. I am reporting. However, such a method is difficult to dissolve due to its high molecular weight, and the polymer concentration in the spinning stock solution must be lowered, which leaves a problem in productivity.

Special Table 2012-522142

"Polymer's Advanced Technologies" (Polym.Adv.Technol), 2008, Vol. 20, p. 857-862 "Polymer", 2006, Vol. 47, p. 4445-4453

As described above, in general, wet spinning and dry wet spinning cause rapid mutual diffusion at the boundary between the initial fiber and the coagulation bath and coagulation formation due to the coagulation formation process, and at this time, defects such as voids and the like occur. Is likely to occur. Further, there is a problem that a high draw ratio cannot be applied in the subsequent drawing step and the mechanical properties of the product are deteriorated.

A method of suppressing the generation of voids by using a large amount of solvent in the coagulation bath is generally taken, but there remains an environmental load problem for industrial use.

Further, in order to obtain acrylic fibers having high orientation and high physical characteristics, a method of gel-spinning an ultra-high molecular weight polymer by using a coagulation bath at 0 ° C. or lower has been reported, but this method is productive and spinning. Stability remains an issue.

An object of the present invention is to provide a fiber having high physical properties such as high tensile strength and tensile elastic modulus without using an ultrahigh molecular weight polymer.

The problem is solved by the present invention.
The fiber of the present invention is a fiber formed from a vinyl-based polymer having an ultimate viscosity of 1.3 to 5.0 dL / g, and has a crystal orientation degree of 96. It is a fiber that is 6 to 98%.

Fibers of the present invention, the intensity of the diffraction peak apex with an apex at 2θ = 36 ± 1 in ° observed in the diffraction profile of the meridian of measured fibers using a wide-angle X-ray diffraction (I _A)
The 2 [Theta] = 40 the intensity of the diffraction peak apex with an apex at the ± 1 ° _(I B)
The ratio of _(I A / I _B) is 0.8 to 2.0, the tensile strength is 0.7～2.5GPa, it is preferred tensile modulus of 15～40GPa.

The fibers of the present invention preferably have a fiber density of 1.14 to 1.22 g / cm ^3.
In the fiber of the present invention, the vinyl-based polymer is a polyacrylonitrile-based polymer, the polyacrylonitrile-based polymer has a number average molecular weight of 100,000 to 800,000, and the copolymerization rate of acrylonitrile is 90 mol% or more. Is preferable.

The spinning stock solution used for producing the fiber of the present invention is a spinning stock solution in which a vinyl polymer having an ultimate viscosity of 1.3 to 4.0 dL / g is dissolved in an ionic liquid.

The spinning stock solution of the present invention is preferably a polyacrylonitrile-based polymer in which the vinyl-based polymer has a number average molecular weight of 100,000 to 400,000.
In the spinning stock solution of the present invention, it is preferable that the cation species of the ionic liquid is imidazolium-based.
In the spinning stock solution of the present invention, it is preferable that the cation species of the ionic liquid is a 1,3-dialkylimidazolium type.
In the spinning stock solution of the present invention, it is preferable that the cation species of the ionic liquid is one or more of 1-butyl-3-methylimidazolium and 1-ethyl-3-methylimidazolium.

In the spinning stock solution of the present invention, it is preferable that the anion species of the ionic liquid is one or more of chloride ion, bromine ion and iodide ion.
In the spinning stock solution of the present invention, the ionic liquid is preferably one or more of 1-butyl-3-methylimidazolium chloride and 1-ethyl-3-methylimidazolium chloride.

In the spinning stock solution of the present invention, the vinyl-based polymer is a polyacrylonitrile-based polymer having a number average molecular weight of 100,000 to 800,000, and the content of the polyacrylonitrile-based polymer is based on the mass of the spinning stock solution. It is preferably 5 to 30% by mass.

In the present invention, even if a vinyl-based polymer such as an acrylic polymer having a general molecular weight that can be industrially used and has an ultimate viscosity of 1.3 to 5.0 dL / g is used, this vinyl-based polymer is also used. Is dissolved in an ionic liquid to prepare a spinning stock solution, and the spinning stock solution is gel-spun at a coagulation liquid temperature close to room temperature by a dry-wet spinning method, so that the fiber formation rate due to coagulation can be suppressed to a moderate rate. It is possible to obtain fibers having a uniform structure and a dense structure with few voids. In addition, the tension at the time of taking from the coagulation bath can be reduced, which makes it possible to control the polymer orientation in the coagulation bath and improve the stretchability, and the productivity can be remarkably increased. By controlling the polymer orientation at the initial stage of spinning, there is also an effect that stretching can be applied reasonably even in the subsequent drawing step.

The present invention is an invention produced as a result of diligent studies by us, and by this method, a vinyl polymer such as an acrylic polymer having a general molecular weight that can be industrially used can be used as a coagulant in a coagulation bath. Although the temperature is close to room temperature, it is possible to produce fibers with mechanically high performance, high strength and high elastic modulus.

It is the schematic of the dry-wet spinning apparatus that can be suitably used in this invention. This apparatus was used in the spinning steps in Examples 1 to 5, Reference Examples 1 and 2, and Comparative Examples 1 and 2. It is the schematic of the heating chamber which can be suitably used in this invention. This device was used in the stretching steps of Examples 1 to 5, Reference Examples 1 to 3, and Comparative Examples 1 and 2. It is a schematic diagram of a dry-wet spinning apparatus that can be suitably used in the present invention, and is particularly suitable when a large amount of jet stretch is applied. This device was used in the spinning process in Reference Example 3.

In the production of the fiber of the present invention, a spinning step is preferably performed using a dry-wet spinning apparatus as shown in FIG. 1 or 3, and a drawing step is preferably performed using a heating chamber as shown in FIG. ..

The spinning process by the apparatus as shown in FIG. 1 is adopted in Examples 1 to 5, Reference Examples 1 and 2 and Comparative Examples 1 and 2 described later, and the spinning process by the apparatus as shown in FIG. Is adopted in Reference Example 3 described later. Further, the stretching step by the apparatus as shown in FIG. 2 is adopted in Examples 1 to 5, Reference Examples 1 to 3, and Comparative Examples 1 and 2 described later.

In the dry-wet spinning apparatus shown in FIG. 1, the spinning stock solution stored in the stock solution tank 2 heated to an appropriate temperature by the heater 1 is passed through the nozzle 3 into the coagulation bath 5 (the liquid level of the coagulation liquid is indicated by 10). Extruded into a fibrous form. The fibers 11 that have passed through the coagulation bath 5 via the roll 4A pass through the first cleaning tank 6 (the liquid level of the cleaning liquid is indicated by 10) via the roll 4B, pass through the roll 4C, and pass through the second cleaning tank 7 (The liquid level of the washing liquid is indicated by 10), the washing liquid is washed, passed through the dryer 8 via the roll 4D, dried, and then wound up in the winder 9.

The dry-wet spinning apparatus shown in FIG. 3 is a dry-wet spinning apparatus shown in FIG. 1 in which the undiluted spinning solution is wound at high speed immediately after being discharged from the discharge hole of the nozzle 3 and is subjected to high stretching. .. The fibers coagulated in the coagulation bath 5 pass through the first washing tank 6 and the second washing tank 7 to be washed, and pass through the dryer 8 to be dried, similarly to the dry-wet spinning apparatus shown in FIG. After being wound, it is wound up in the winder 9. In the apparatus shown in FIG. 2, the fibers are supplied into the heating chamber 13 via the roll 4E in the creel 12, heated by the hot plate, and wound on the roll 4F in the winder 9, but the rotation speed of the roll 4F. By increasing the rotation speed of the roll 4E, the fibers are stretched in the heating chamber 13.

[Vinyl polymer]
In the present invention, the following monomers can be used as the vinyl polymer. That is, acrylic acid esters typified by acrylonitrile, methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, hydroxypropyl acrylate and the like; methacrylic acid. Represented by methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, n-hexyl methacrylate, cyclohexyl methacrylate, uralyl methacrylate, 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, diethylaminoethyl methacrylate, etc. Methacrylic acid esters; acrylic acid, methacrylic acid, acrylamide itaconate, N-methylol acrylamide, diacetone acrylamide, styrene, vinyl toluene, vinyl acetate, vinyl chloride, vinylidene chloride, vinyl bromide, vinylidene bromide, fluoride Unsaturated monomers such as vinyl and vinylidene fluoride; p-sulfophenyl methacrylic acid, methacrylic sulfonic acid, allyl sulfonic acid, styrene sulfonic acid, 2-acrylamide-2-methylpropane sulfonic acid, and alkali metal salts thereof, etc. Can be exemplified.

Among them, a polyacrylonitrile-based polymer using acrylonitrile as a monomer for forming a vinyl-based polymer (hereinafter, may be abbreviated as “PAN-based polymer”) is excellent in light resistance when made into a fiber. Therefore, it is preferable.

[PAN-based polymer]
A PAN-based polymer that can be preferably used in the present invention will be described.
As the PAN-based polymer, a homopolymer of acrylonitrile (AN) (PAN homopolymer) or a copolymer of AN and another monomer (PAN-based copolymer) can be used (hereinafter, PAN alone). The polymer and the PAN-based copolymer are collectively abbreviated as "PAN-based polymer").

The PAN-based polymer preferably contains 90.0 mol% or more of structural units derived from AN in order to improve spinning stability and improve the quality and performance of acrylic fibers and flame-resistant fibers and carbon fibers made of the acrylic fibers. When the structural unit derived from AN is 90.0 mol% or more, it is easy to secure high spinning stability and stretchability. The structural unit derived from AN is more preferably 94.0 mol% or more.

The monomer to be copolymerized is not particularly limited as long as it is a monomer copolymerizable with AN, and for example, acrylic acid esters such as methyl acrylate and ethyl acrylate; methacrylic acid esters such as ethyl methacrylate; acrylic acid, Unsaturated monomers such as methacrylic acid, maleic acid, itaconic acid, and acrylamide; examples thereof include metallicyl sulfonic acid, allyl sulfonic acid, styrene sulfonic acid, and alkali metals thereof. These other monomers may be used alone or in combination of two or more.

[Molecular weight (extreme viscosity, number average molecular weight)]
The ultimate viscosity of a vinyl polymer such as a PAN polymer used for the fiber of the present invention is 1.3 to 5.0 dL / g. If it is 1.3 dL / g or more, it is easy to achieve high stretching in the stretching step described later, and if it is 5.0 dL / g or less, it is easy to achieve stable high productivity. From the above viewpoint, the ultimate viscosity is more preferably 1.4 to 4.0 dL / g, further preferably 1.5 to 3.0 dL / g.

Similarly, the number average molecular weight (Mn) of the vinyl polymer such as the PAN polymer used for the fiber of the present invention is preferably 100,000 to 800,000. If it is 100,000 or more, it is easy to achieve high stretching in the stretching step described later, and if it is 800,000 or less, it is easy to achieve stable high productivity. From the above viewpoint, the number average molecular weight (Mn) is more preferably 150,000 to 500,000, and even more preferably 170,000 to 400,000.

[Polymerization method]
The method for polymerizing a vinyl-based polymer such as a PAN-based polymer is not particularly limited, and a solution polymerization method, a suspension polymerization method, an emulsion polymerization method, or the like can be used.

[Ionic liquid]
An ionic liquid is a kind of low-temperature molten salt composed of organic ions having a relatively large molecular size, which is in a liquid state at 100 ° C. or lower. Its features include, for example, the following.

(1) Non-flammable and extremely low vapor pressure reduces the risk of explosion and fire (2) Extremely low vapor pressure and extremely low probability of inhalation into the lung (3) Chemically and thermally stable Therefore, it has good recyclability (4) It has abundant combinations of anions and cations, and its properties such as hydrophilicity, viscosity, and melting point can be tuned (5) It can dissolve various substances (5) Ionics. Depending on the liquid type, it can be arbitrarily mixed and separated from water. (6) It can be used as a relatively stable liquid in a supercooled state.

These properties are also useful in the development of acrylic fibers. In the present invention, sudden coagulation does not occur even when water is used as the coagulation liquid in the coagulation bath, and sudden coagulation accompanied by void formation is suppressed by relatively slow mutual diffusion and gelation that occurs in competition with the coagulation liquid. Achieves uniform fiber. As a result, the amount of solvent used can be reduced compared to the conventional method, and in terms of the environment, it can be manufactured without sucking and exhausting harmful volatile organic solvents as in the conventional production method, which has the effect of reducing the cost of exhaust equipment, etc. There is.

As the ionic liquid in the present invention, ammonium-based, imidazolium-based, pyridinium-based, pyroridinium-based, etc. can be used as the cation species, and halogen-based, tetrafluoroborate, hexafluorophosphoric acid, disianamide, bistrifluoro, etc. Methylsulfonylimide and the like can be used, but the present invention is not particularly limited thereto, and other than these may be used. Among them, as the cationic species, an imidazolium type, particularly a 1,3-dialkylimidazolium type is preferable from the viewpoint of thermal stability and cost.
Further, the anion species is preferably halogen-based from the viewpoint of hydrophilicity and melting point, and more preferably chlorine ion from the viewpoint of cost.

Examples of the cation species having an imidazolium type and the anion species having a halogen type include 1,3-dialkylimidazolium chloride, 1,3-dialkylimidazolium bromide, and 1,3-dialkylimidazolium iodide. .. Among them, 1-butyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium chloride and mixtures thereof are most preferable because they have a low melting point in addition to thermal stability and cost.

[Spinning stock solution]
In the present invention, the spinning stock solution is obtained by dissolving the PAN-based polymer in the ionic liquid. The melting method is not particularly limited, but a vinyl polymer such as a PAN polymer is dispersed in a molten state above the melting point of the ionic liquid or a supercooled liquid state to prepare a slurry, which is then heated to a high temperature. It is desirable to use a spinning stock solution.

If it is a small amount, it can be dissolved using a rotation / revolution mixer or the like. In particular, when a mixer is used in a reduced pressure state, air between the resin powders can be removed, and dispersion of the PAN-based polymer becomes extremely easy, resulting in high efficiency. In some cases, it is also possible to dissolve the polymer by utilizing the heat generated during dissolution.
In the preparation of the spinning stock solution using an ionic liquid, the stirring method and the like are not particularly limited.

Generally, the same polymer as a spinning stock solution in which a vinyl polymer such as a PAN polymer is dissolved using an organic solvent (for example, dimethylformamide (DMF), dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), etc.) When the concentration and temperature are the same, the viscosity is higher when the ionic liquid is used. Therefore, it is preferable to mix and stir with a kneader or the like having torque. Further, when air bubbles are present in the spinning stock solution, it is preferable to perform decompression defoaming treatment or the like from the viewpoint of suppressing yarn breakage in the spinning step described later. In the case of a small amount, it is also preferable to use a commercially available rotation / revolution mixer or the like from the viewpoint of convenience.

The concentration of the spinning stock solution is preferably 5 to 30% by mass. If it is 5% by mass or more, it is easy to achieve a high stretching ratio in the stretching step described later, and if it is 30% by mass or less, gelation in the stock solution tank is unlikely to proceed.
From the above viewpoint, the concentration of the spinning stock solution is more preferably 10 to 20% by mass.

The temperature of the spinning stock solution is preferably 20 to 150 ° C. If it is 20 ° C. or higher, it is easy to handle from the viewpoint of the viscosity of the undiluted solution, and if it is 150 ° C. or lower, gelation in the undiluted solution tank is unlikely to proceed.
From the above viewpoint, the temperature of the spinning stock solution is more preferably 60 to 110 ° C, further preferably 75 to 100 ° C.

[Spinning means]
In the present invention, the undiluted spinning solution is extruded from a mold (nozzle or the like), and the coagulation bath promotes coagulation and gelation to form fibers. As the spinning method, a dry-wet spinning method, which is advantageous in terms of fiber quality, can be adopted.

[Distance to coagulation liquid surface]
In the dry-wet spinning method, the distance from the discharge hole to the coagulating liquid surface is preferably 1 to 100 mm. If the length is longer than 1 mm, the coagulating liquid that sways on the liquid surface is less likely to hit the nozzle, and troubles such as nozzle clogging can be avoided. Further, when the length is shorter than 100 mm, it is possible to avoid unnecessary shaking of the fiber, which is effective because fusion can be prevented particularly in terms of production with a multifilament. For the same reason, 7 to 20 mm is more preferable.

[Coagulation bath]
The composition of the coagulation liquid in the coagulation bath is preferably water or a mixed liquid of water and an ionic liquid, and from the viewpoint of coagulation, the composition of water in the coagulation liquid is preferably 30 to 100% by mass. If it is 30% by mass or more, stable spinning is possible under an appropriate solidification rate.

When the vinyl-based polymer coagulates, the ionic liquid is extracted into the coagulation bath and the concentration of the ionic liquid in the coagulation bath increases. Therefore, by supplying water, the water composition of the coagulation liquid is maintained at 30% by mass or more. Is preferable.
The water content of the coagulation liquid is preferably 60% by mass or more, more preferably 80% by mass or more.

The temperature of the coagulating liquid in the coagulation bath is preferably 0 ° C. or higher and 40 ° C. or lower from the viewpoint of coagulation. When the temperature is 0 ° C. or higher, stable spinning is possible under an appropriate solidification rate. Further, when the temperature is 40 ° C. or lower, the generation of voids in the fiber can be suppressed.

From the viewpoint of stabilizing the coagulating liquid, the temperature is preferably 1 ° C. or higher, more preferably 5 ° C. or higher. Further, from the viewpoint of suppressing the generation of voids in the fiber, the temperature is more preferably 30 ° C. or lower, further preferably 15 ° C. or lower.

[Washing and drying]
In the present invention, a washing step in the washing tank and a drying step in the dryer are provided as post-steps following the spinning step. The washing step is performed to remove the ionic liquid remaining inside the fiber to the outside of the fiber at the end of the spinning step. Further, the drying step is performed to evaporate water or the like adhering to the fibers in the washing step.

As the coagulating liquid in the washing tank, it is preferable to use water alone or an aqueous solution in which water and an ionic liquid have a water content of 30 to 100% by mass from the viewpoint of washing efficiency. Efficient cleaning is possible when the composition of water is 30% by mass or more. Further, the temperature of the cleaning liquid is preferably 20 ° C. or higher and 100 ° C. or lower from the viewpoint of cleaning efficiency. Efficient cleaning is possible when the temperature is 20 ° C. or higher. Further, if the temperature is 100 ° C. or lower, the generation of voids during washing can be suppressed.

The cleaning tank may be one tank, but it is preferable to use a plurality of washing tanks and to solidify them in order by inclining the desolvation force from the viewpoint of preventing the generation of voids. Therefore, it is preferable that the temperature of the coagulating liquid in the plurality of washing tanks is gradually increased. The temperature difference between the coagulating liquids in the adjacent coagulation tanks is preferably 10 ° C. or higher, more preferably 20 ° C. or higher.

The temperature of the drying oven is preferably 40 ° C. or higher and 280 ° C. or lower. When the temperature is 40 ° C. or higher, the drying efficiency is good, and when the temperature is 280 ° C. or lower, the decomposition reaction of a vinyl polymer such as PAN can be avoided.

[From spinning process to drawing process]
The dried fibers may be continuously added to the drawing process that continues as they are, or the winding process may be separated once with a winder or the like. Further, drying may be added in the wound state.

[Hot plate stretching]
The present invention includes a step of stretching dried fibers in a heating atmosphere. As the heating means, various heating furnaces, hot plates, steam stretching machines and the like can be used. In particular, in the present invention, since the stretchability of the fiber is significantly improved by effectively using the ionic liquid in the spinning process, the fiber can be sufficiently stretched by hot plate stretching by a heating chamber. Since the fiber can be thermally stretched on the hot plate with a simple device, there is an advantage that the fiber can be highly stretched with a small capital investment and a small driving cost. The heating temperature is preferably 100 ° C. or higher and 280 ° C. or lower in terms of stretching stability. When the temperature is 100 ° C. or higher, the stretchability is high and stable production is possible. If the temperature is 280 ° C. or lower, the decomposition reaction of PAN can be avoided, so that the yarn can be drawn stably with less yarn breakage. The hot plate stretching is not particularly limited as to whether it is a contact type or a non-contact type with fibers.

[Stretching ratio]
The draw ratio in the present invention is divided into a draw ratio in the so-called spinning step of drawing in the coagulation bath and the washing tank and a draw ratio in a heating chamber when the heat is later drawn. Further, the draw ratio of the spinning process is multiplied by the draw ratio of the heating chamber to obtain the total draw ratio. Definitions of these draw ratio terms will be described in more detail in the Examples section.

なお、ノズル孔での吐出線速度とは、（式２）より算出することができる。

[Jet Stretch (JS) Spinning]
The spinning method of the present invention is also characterized in that it can be wound at high speed and stretched at a high speed immediately after the nozzle is discharged. Generally, the stretch ratio due to the linear velocity at the nozzle discharge part and the velocity of the first take-up roll (corresponding to the 4A roll in FIG. 1; corresponding to the 4G roll in FIG. 3) is jet stretched. It is called (JS) and is defined by (Equation 1).

The discharge line velocity at the nozzle hole can be calculated from (Equation 2).

When high stretching is applied by JS, it is possible to use the fiber drawn by stretching from the first take-up roll as an acrylic fiber having sufficient mechanical properties, and in particular, sufficient physical properties can be obtained for clothing applications and the like. .. The spinning device in this case may be a multi-stage tank as shown in FIGS. 1 and 3, but a simple device in which the coagulation bath 5, the first washing tank 6 and the second washing tank 7 are combined into one tank may be used. ..

Further, if higher mechanical properties are required, a hot plate stretching step may be provided later. When high stretching is applied in JS, there is an advantage that the hot plate stretching step to be installed later can be completed by a relatively small-scale device.

When high stretching is applied by JS, it is preferably 400 times or less. If it is 400 times or less, it is less likely to be affected by friction with water, and thread breakage is less likely to occur. Further, even in the case of the dry-wet spinning method, if it is 400 times or less, liquid splashing is unlikely to occur at the interface of the coagulating liquid, and stable production is possible. From the above viewpoint, JS is more preferably 200 times or less, and further preferably 170 times or less.
In this case, the subsequent draw ratio of the fiber may be 5 times or less.

Of course, JS may be conservative and may be stretched in a subsequent stretching step or the like. In that case, JS is preferably 0.1 to 49.9 times. When it is 0.1 times or more, stable spinning is possible without loosening the fibers.

In this case, the subsequent draw ratio of the fibers is 1.5 to 5 times the draw ratio between the first roll in the coagulation bath and the roll immediately before the heating chamber, and the atmosphere temperature is 130 to 220 ° C. in the heating chamber. It is preferable to stretch at a stretching ratio of 5 to 15 times.

From the viewpoint of ease of drawing the fibers, the atmospheric temperature in the heating chamber is more preferably 140 to 190 ° C., further preferably 150 to 170 ° C., and the fiber draw ratio is more preferably 12 times or less.

[Fiber diameter, fiber length]
The fiber diameter of the fiber of the present invention is not particularly limited, but the fiber diameter is preferably 5 to 50 μm, more preferably 15 to 40 μm, still more preferably 20 to 30 μm from the viewpoint of easy fiber formation. There are no particular restrictions on the forms such as long fibers and short fibers.

[Crystal orientation]
The crystal orientation of the fibers of the present invention is 96.6 to 98%. When the degree of crystal orientation is 90% or more, it is preferable that the degree of crystal orientation is basically high in producing fibers having mechanically high physical characteristics. From the viewpoint of obtaining high tensile strength, the degree of crystal orientation is preferably 92% or more, more preferably 95% or more.

In particular, in acrylic fibers, a high degree of orientation has been achieved by gel spinning of an ultra-high molecular weight PAN having a molecular weight of 2.3 million or more, but there is an industrial problem. For example, in a PAN-based polymer having an ultimate viscosity of 1.3 to 5.0 dL / g, which can be mass-produced industrially, there is a large wall with a crystal orientation degree of about 93%, and it has been considered difficult to exceed it. rice field. However, in the present invention, this has been achieved through our diligent studies. Details of the apparatus used, the measurement method, and the like are described in the section of Examples.

[Wide-angle X-ray of _I A _{/ I} B]
Fibers prepared according to the invention the intensity of the diffraction peak apex with an apex at 2θ = 36 ± 1 in ° observed in the diffraction profile of the measured meridian at the wide angle X-ray diffraction (I _A)
The 2 [Theta] = 40 the intensity of the diffraction peak apex with an apex at the ± 1 ° _(I B)
It is characterized by the ratio _(I A / I _B) with. Whether I _A and I _B is what represents is debatable still, but for example, the diffraction I _A is in Non-Patent Document 2 adopts a planar zigzag structure polymer, I _B is-helix structure α- It is reported that it shows the diffraction of the polymer, which is considered to be a general recognition.

I _{A /} I _B of the fibers of the present invention is preferably in terms of physical properties to be at 0.8 to 2.0 or more, particularly elastic modulus expressed readily achieve this by spinning method using an ionic liquid of the present invention can do. From the point of view, _I A / _{I B} of the fibers of the present invention is more preferably 1.0 or more, more preferably 1.25 or more.

[Tensile strength, tensile elastic modulus]
The tensile strength of the fiber of the present invention is preferably 0.7 to 2.5 GPa. When the tensile strength is 0.7 or more, problems in passability in the processing process and use of the product are reduced. From the above viewpoint, the tensile strength is more preferably 0.9 GPa or more, and further preferably 1.2 GPa or more.

The tensile elastic modulus of the fiber of the present invention is preferably 15 to 40 GPa. When the tensile elastic modulus is 15 or more, problems in passability in the processing process and use of the product are reduced. From the above viewpoint, the tensile elastic modulus is more preferably 19 GPa or more, and further preferably 22 GPa or more.

[Fiber density]
The density of the fiber of the present invention is not limited, but is preferably ^{1.14 to 1.22 g / cm 3.} When it is 1.14 g / cm ³ or more, the structure inside the fiber is dense, which is advantageous for expressing physical properties such as strength and elastic modulus. Further, if it is 1.22 g / cm ³ or less, an extreme decrease in elongation can be prevented.
From the point of view, the fiber density is more preferably 1.17~1.20g / cm ^3, more preferably 1.18~1.19g / cm ^3.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited thereto.
In the examples, each physical property value and characteristic was measured by the following method.

<Measurement of copolymer composition>
It was measured by 1H-NMR method (JEOL GSX-400 type superconducting FT-NMR).

<Measurement of crystal orientation by wide-angle X-ray diffraction>
The X-ray fiber graphic by the imaging plate system was measured using a RA-micro7 X-ray generator manufactured by Rigaku. The sample was photographed by vertically incident X-rays on the sample using Cu-Kα rays (wavelength 0.15418 nm) monochromaticized with a Ni filter at an output voltage of 40 kV and an output current of 20 mA and exposed for a predetermined time.

For the diffraction around the equatorial diffraction angle 2θ = 17 ° of the acrylic fiber bundle, the diffraction profile in the azimuth direction is obtained, and the curve fitting is approximated by two pseudo Voigt functions and one baseline to obtain the peak. It was calculated by the following formula from _{the total W total} of the half price range (°).
Degree of orientation = (360-W _total ) / (360)

<Determination of _I A / _{I B} by wide angle X-ray diffraction>
A RU-200 type X-ray generator manufactured by Rigaku Denki Co., Ltd. was used, and a Cu-kα ray (0.1548 nm) monochromaticized with a Ni filter was used as the radiation source (output voltage 40 kV, current 150 mA) for measurement. A goniometer PMG-GA manufactured by Rigaku Denki Co., Ltd. was used. Measurements were made in the meridian direction. Meridian diffraction angle 2θ = 36 °, I _A and I _B peak each diffraction around 40 ° was observed. To obtain a diffraction angle direction of the profile, fitting of the curve performs approximated by two Gaussian functions and one of the baseline, was determined I A _/ I _B.

<Measurement of fineness>
For the measurement, DENICON DC-21 manufactured by Search Co., Ltd. was used. The measurement was performed in a constant temperature and humidity chamber (20 ° C., 65%). The measurement test length is 2.5 cm and the weight is 0.4 g.

<Tensile strength, tensile elastic modulus, tensile elongation>
The tensile properties were measured using a Shimadzu small desktop tester EZTest EZ-S tensile tester manufactured by Shimadzu Corporation under standard conditions of 20 ° C. and 65% RH. The sample used was kept in the standard state for 24 hours or more before the test. The test conditions were a 50 N load cell, an initial sample length of 20 mm, and a tensile speed of 20 mm / min. The breaking strength, breaking elongation, and initial elastic modulus were obtained from the obtained stress-strain curve.

<Extreme viscosity measurement>
Approximately 10 g of the sample is held in a dryer with an ambient temperature of 80 ° C. for 120 minutes to dry, then precisely weighed, DMF is added and completely dissolved at room temperature to prepare PAN / DMF solutions having 3 to 4 concentrations of c. (In the present invention, the polyacrylonitrile used in Examples 1 to 3, Reference Examples 1 to 3 and Comparative Examples 1 to 2 is 0.25 g / dL, 0.50 g / dL, 0.75 g / dL, 1.00 g. The four types of / dL were used, and the polyacrylonitrile used in Examples 4 to 5 was adjusted to 0.17 g / dL, 0.33 g / dL, and 0.50 g / dL). Using an Ubbelohde viscometer in a constant temperature bath controlled at 25 ° C., the falling time of the blank DMF solution and the sample DMF solution in which the sample is dissolved is measured. After obtaining the average value of the measured values of each of the five times, the specific viscosity ηsp is calculated by the formula (1), where the falling time of the blank DMF is t0 and the falling speed of the sample DMF solution is t. Subsequently, the relationship between ηsp / c and the concentration c of each concentration was plotted, and the ultimate viscosity [η] was obtained from the intercept when extrapolated from c to 0 based on Huggins' equation (2).
ηsp = (t / t0) -1 ... (1)
ηsp / c = [η] + k'[η] 2c ・ ・ ・ (2)

<Measurement of number average molecular weight>
The number average molecular weight is a value measured by gel permeation chromatography (GPC). What is the number average molecular weight? When there are Ni polymers with a molecular weight of Mi, the following formula is used. Number average molecular weight (Mn) = Σ (NiMi) / Σ (Ni)
It is a value represented by. For the number average molecular weight, use a relative value in terms of polystyrene.

<Densitometry>
The fiber density was measured using the floating and sinking method in a toluene-carbon tetrachloride system at 25 ° C.
Weigh about 1 mg of 5 mm long fiber, adjust the toluene-carbon tetrachloride mixed solution so that most of the fiber floats near the center of the glass container, and measure the liquid density at that time using a pycnometer. The density was set to.

<Drawing ratio in spinning process>
The ratio of the roll speed of the first take-up roll that winds the spinning stock solution to the take-up speed of the winder (for example, in FIG. 1, corresponds to [4D roll speed / 4A roll speed]) is used as the draw ratio in the spinning process. did.

<Stretching ratio in the heating chamber>
The ratio of the speed of the creel supplied to the heating chamber and the speed of the winder after leaving the heating chamber (for example, corresponding to [4F roll speed / 4E roll speed] in FIG. 2) was taken as the stretching ratio in the heating chamber. ..

<Total draw ratio>
The total draw ratio was obtained by multiplying the draw ratio in the above spinning process by the draw ratio in the same heating chamber. Therefore, the jet stretch ratio is not added to the total stretch ratio in the present invention.

[Example 1]
First, the spinning process was performed by a dry-wet spinning apparatus as shown in FIG.
Polyacrylonitrile (extreme viscosity = 1.56 dL / g, number average molecular weight = 190,000, AN composition ≥ 99%) was dissolved in 1-butyl-3-methylimidazolium chloride (BimCL), and the solid content concentration was 15 mass. % PAN-based polymer-containing solution was prepared. The PAN-based polymer-containing solution was heated to 90 ° C. and packed in a stock solution tank 2 which was also heated to 90 ° C. with a heater 1 to prepare a spinning stock solution. The spinning stock solution was quantitatively discharged at 0.30 g / min from a 1-hole discharge hole having a diameter of 0.52 mm of the nozzle 3, and was solidified by passing through a coagulation bath 5. The winding speed of the roll 4A immediately after solidification was 2.6 m / min, and the stretching ratio by jet stretching was 2.2 times. An air gap of 10 mm was provided from the discharge hole of the nozzle 3 to the liquid level 10 of the coagulation bath 5, and dry-wet spinning was performed. The coagulating liquid in the coagulation bath 5 was water at 10 ° C., the subsequent cleaning liquid in the first washing tank 6 was water at 32 ° C., and the cleaning liquid in the second washing tank 7 was water at 60 ° C. to wash the fibers.

Even after entering the coagulation bath 5, mutual diffusion of BmimCL and water inside and outside the fiber was slow, the fiber was transparent in the coagulation bath 5, and a transparent and uniform fiber shape was confirmed by microscopic observation. It was confirmed that diffusion proceeded in the subsequent first cleaning tank 6 and second cleaning tank 7, and BmimCL completely diffused to the outside of the fiber.

After the second washing tank 7, a dryer 8 having an internal atmospheric temperature of 60 ° C. was prepared, and the fibers were continuously dried and wound by a winder. The draw ratio of the spinning step between the roll 4A in the coagulation bath and the roll 4C in the second washing tank was set to 3 times.

Next, a stretching step was performed in a heating chamber as shown in FIG.
The wound dried fibers were stretched in a heating chamber 13 having a length of 2 m. The temperature of the chamber was 160 ° C., the draw ratio in this step was 10 times, and stable spinning was possible, achieving a total draw ratio of 30 times.

The diameter of this acrylic fiber is 26 μm, the tensile strength is 0.97 GPa, the elastic modulus is 23.0 GPa, the elongation is 11.0%, the density is 1.19 g / cm ³ , the crystal orientation is 96.6%, and the meridional direction. X-ray diffraction intensity ratio of _(I a / I _B) was 1.29.

[Example 2]
Acrylic fibers were obtained in the same manner as in Example 1 except that the drawing was performed 9 times (total drawing ratio 27 times) in the heating chamber. The diameter of this acrylic fiber is 27 μm, the tensile strength is 1.11 GPa, the elastic modulus is 23.0 GPa, the elongation is 10.8%, the density is 1.18 g / cm ³ , the crystal orientation is 96.8%, and the meridional direction. X-ray diffraction intensity ratio of _(I a / I _B) was 1.33.

[Reference example 1]
Acrylic fibers were obtained in the same manner as in Example 1 except that the solvent was changed to 1-ethyl-3-methylimidazolium chloride (EmimCL). Fiber diameter is 33 μm, tensile strength is 1.03 GPa, elastic modulus is 19.4 GPa, elongation is 10.3%, density is 1.20 g / cm ³ , crystal orientation is 94.2%, X in the meridian direction. ray diffraction intensity ratio _(I a / I _B) was 1.00.

[Reference example 2]
Acrylic fibers are obtained by the same method as in Example 1 except that the undiluted solution temperature is 95 ° C., the coagulation bath temperature is 30 ° C., the draw ratio in the heating chamber is 6 times, and the total draw ratio is 18 times. rice field. In this method, the fibers became slightly cloudy in the coagulation bath. The diameter of this acrylic fiber is 31 μm, the tensile strength is 1.03 GPa, the elastic modulus is 21.6 GPa, the elongation is 10.3%, the density is 1.18 g / cm ³ , the crystal orientation is 92.9%, and the meridional direction. X-ray diffraction intensity ratio of _(I a / I _B) of 1.19.

[Example 3]
Acrylic fibers are obtained by the same method as in Example 1 except that the undiluted solution temperature is 95 ° C., the coagulation bath temperature is 2 ° C., the draw ratio in the heating chamber is 8 times, and the total draw ratio is 24 times. rice field. The diameter of this acrylic fiber is 26 μm, the tensile strength is 1.45 GPa, the elastic modulus is 25.2 GPa, the elongation is 9.9%, the density is 1.19 g / cm ³ , the crystal orientation is 96.6, and the meridional direction. X-ray diffraction intensity ratio _(I a / I _B) was 1.49.

[Reference example 3]
The undiluted solution temperature was set to 95 ° C., and the spinning process was performed by a dry-wet spinning device as shown in FIG. 3 instead of the dry-wet spinning device as shown in FIG. 1, and the winding speed of the roll 4G immediately after the coagulation bath was performed. Was increased to 193.0 m / min to change the draw ratio by jet stretching to 160.8 times, the internal atmosphere temperature of the dryer 8 was changed from 60 ° C to 25 ° C without stretching in the spinning process, and heating was performed. Acrylic fibers were obtained in the same manner as in Example 1 except that the draw ratio in the chamber 13 was set to 3 times and the total draw ratio was set to 9 times. The diameter of the acrylic fiber was 9 μm, the tensile strength was 1.26 GPa, the elastic modulus was 18.9 GPa, the elongation was 11.9%, and the density was 1.18 g / cm ³ . Since the sample volume was small amounts, X-rays diffraction intensity ratio of the crystal orientation and the meridian _(I A _/ I _B) was not measured.

[Comparative Example 1]
Except for the fact that the solvent was dimethylformamide (DMF), the air gap was 5 mm, the cleaning temperature of the first cleaning tank was 35 ° C, the stretching ratio in the heating chamber was 4 times, and the total stretching ratio was 12 times. Acrylic fibers were obtained in the same manner as in Example 1. At the moment of entering the coagulation bath, cloudy fibers were formed, and a large number of voids were observed by microscopic observation. The draw ratio of 4 times in the heating chamber was the maximum draw ratio, and since the yarn started to break at this ratio, the total draw ratio was limited to 12 times.

The diameter of this acrylic fiber is 38 μm, the tensile strength is 0.56 GPa, the elastic modulus is 8.9 GPa, the elongation is 13.0%, the density is 1.13 g / cm ³ , the crystal orientation is 87.2%, and the meridional direction. X-ray diffraction intensity ratio of _(I a / I _B) was 0.32.

[Comparative Example 2]
Except for the fact that the solvent was dimethylacetamide (DMAc), the air gap was 5 mm, the cleaning temperature of the first cleaning tank was 35 ° C, the stretching ratio in the heating chamber was 3 times, and the total stretching ratio was 9 times. Acrylic fibers were obtained in the same manner as in Example 1. At the moment of entering the coagulation bath, cloudy fibers were formed, and a large number of voids were observed by microscopic observation. The draw ratio of 3 times in the heating chamber was the maximum draw ratio, and since the yarn started to break at this ratio, the total draw ratio was limited to 9 times.

The diameter of this acrylic fiber is 40 μm, the tensile strength is 0.47 GPa, the elastic modulus is 7.7 GPa, the elongation is 16.0%, the density is 1.13 g / cm ³ , the crystal orientation is 88.2%, and the meridional direction. X-ray diffraction intensity ratio of _(I a / I _B) was 0.34.

[Example 4]
First, the spinning process was performed by a dry-wet spinning apparatus as shown in FIG.
Polyacrylonitrile (extreme viscosity = 3.90 dL / g, number average molecular weight = 380,000, AN composition ≥ 99%) was dissolved in 1-butyl-3-methylimidazolium chloride (BimCL), and the solid content concentration was 10 mass. % PAN-based polymer-containing solution was prepared. The PAN-based polymer-containing solution was heated to 100 ° C. and packed in a stock solution tank 2 which was also heated to 100 ° C. with a heater 1 to prepare a spinning stock solution. The spinning stock solution was quantitatively discharged at 0.30 g / min from a 1-hole discharge hole having a diameter of 0.52 mm of the nozzle 3, and was solidified by passing through a coagulation bath 5. The winding speed of the roll 4A immediately after solidification was 2.6 m / min, and the stretching ratio by jet stretching was 2.2 times. An air gap of 10 mm was provided from the discharge hole of the nozzle 3 to the liquid level 10 of the coagulation bath 5, and dry-wet spinning was performed. The coagulating liquid in the coagulation bath 5 was water at 2 ° C., the subsequent cleaning liquid in the first washing tank 6 was water at 30 ° C., and the cleaning liquid in the second washing tank 7 was water at 60 ° C. to wash the fibers.

Even after entering the coagulation bath 5, mutual diffusion of BmimCL and water inside and outside the fiber was slow, the fiber was transparent in the coagulation bath 5, and a transparent and uniform fiber shape was confirmed by microscopic observation. It was confirmed that diffusion proceeded in the subsequent first cleaning tank 6 and second cleaning tank 7, and BmimCL completely diffused to the outside of the fiber.

After the second washing tank 7, a dryer 8 having an internal atmospheric temperature of 60 ° C. was prepared, and the fibers were continuously dried and wound by a winder. The draw ratio of the spinning step between the roll 4A in the coagulation bath and the roll 4C in the second washing tank was set to 3 times.

Next, a stretching step was performed in a heating chamber as shown in FIG.
The wound dried fibers were stretched in a heating chamber 13 having a length of 2 m. The temperature of the chamber was 185 ° C., the draw ratio in this step was 9 times, and stable spinning was possible, achieving a total draw ratio of 27 times.

The diameter of this acrylic fiber is 20 μm, the tensile strength is 1.83 GPa, the elastic modulus is 25.8 GPa, the elongation is 13.6%, the density is 1.18 g / cm ³ , the crystal orientation is 97.1%, and the meridional direction. X-ray diffraction intensity ratio of _(I a / I _B) was 1.54.

[Example 5]
The same as in Example 4 except that the solid content concentration was 12% by mass, the stock solution temperature was 120 ° C., the heating chamber temperature was 190 ° C., the stretching in the heating chamber was 10 times, and the total stretching ratio was 30 times. Acrylic fibers were obtained by the method. The diameter of this acrylic fiber is 22 μm, the tensile strength is 1.88 GPa, the elastic modulus is 25.8 GPa, the elongation is 12.8%, the density is 1.18 g / cm ³ , the crystal orientation is 97.0%, and the meridional direction. X-ray diffraction intensity ratio of _(I a / I _B) was 1.50.

1 Heater 2 Stock solution tank 3 Nozzle 4 A roll (A speed)
4B roll (B speed)
4C roll (C speed)
4D roll (D speed)
4E roll (E speed)
4F roll (F speed)
4G roll (G speed)
5 Coagulation bath 6 1st cleaning tank 7 2nd cleaning tank 8 Dryer 9 Winder 10 Coagulant or cleaning liquid level 11 Fiber 12 Creel 13 Heating chamber

Claims (12)

A fiber formed from a vinyl-based polymer, the vinyl-based polymer having an ultimate viscosity of 1.3 to 5.0 dL / g, and a crystal orientation degree of 96 measured using wide-angle X-ray diffraction. .6 to 98% fiber. Intensity of the diffraction peak apex with an apex at 2θ = 36 ± 1 in ° observed in the diffraction profile of the meridian of measured fibers using a wide-angle X-ray diffraction (I _A)
The 2 [Theta] = 40 the intensity of the diffraction peak apex with an apex at the ± 1 ° _(I B)
The ratio of _(I A / I _B) is 0.8 to 2.0, the tensile strength is 0.7～2.5GPa, according to claim 1 tensile modulus of 15~40GPa fibers .. The fiber according to claim 1 or 2, wherein the fiber density is 1.14 to 1.22 g / cm ^3. The vinyl-based polymer is a polyacrylonitrile-based polymer.
The fiber according to any one of claims 1 to 3, wherein the polyacrylonitrile-based polymer has a number average molecular weight of 100,000 to 800,000 and a copolymerization rate of acrylonitrile of 90 mol% or more. The spinning stock solution used for producing a fiber according to any one of claims 1 to 4, wherein a vinyl polymer having an ultimate viscosity of 1.3 to 4.0 dL / g is dissolved in an ionic liquid. The spinning stock solution according to claim 5, wherein the vinyl-based polymer is a polyacrylonitrile-based polymer having a number average molecular weight of 100,000 to 400,000. The undiluted spinning solution according to claim 5 or 6, wherein the cation species of the ionic liquid is an imidazolium type. The undiluted spinning solution according to claim 7, wherein the cation species of the ionic liquid is a 1,3-dialkylimidazolium type. The undiluted spinning solution according to claim 8, wherein the cation species of the ionic liquid is one or more of 1-butyl-3-methylimidazolium and 1-ethyl-3-methylimidazolium. The undiluted spinning solution according to claim 5 or 6, wherein the anion species of the ionic liquid comprises one or more of chloride ion, bromine ion, and iodide ion. The undiluted spinning solution according to any one of claims 5 to 10, wherein the ionic liquid is at least one of 1-butyl-3-methylimidazolium chloride and 1-ethyl-3-methylimidazolium chloride. The spinning stock solution according to any one of claims 5 to 11, wherein the content of the polyacrylonitrile-based polymer is 5 to 30% by mass with respect to the mass of the spinning stock solution.

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