JPH05106110A - Manufacture of un-spun highly-oriented acrylic short fiber - Google Patents

Abstract

PURPOSE: To obtain the titled fiber having a large surface area, excellent physical properties and bonding properties and useful as an asbestos-substitutive fiber or the like. by fiber-forming a specified mixture under specific conditions and beating the formed fiber. CONSTITUTION: Acrylonitrile (co-)polymer having 10,000-600,000 viscosity average molecular weight obtained by polymerizing >=70 wt.% acrylonitrile and <=30 wt.% copolymerizable monomer is mixed with 5-100% water to the (co-)polymer. The mixture is heated to its melting temperature or higher under enclosed conditions to form an amorphous melt and then the resultant melt is cooled to the temperature between the melting and solidifying temperatures to obtain a semicrystalline melt phase. The obtained melt phase is extruded into an external atmosphere to obtain extrudates having cross-sectional structures of completely arrayed and laminated planar fibrils or the like, fibrous crystalline structures and >=70% degree of orientation. The extrudates are drawn in the gaseous atmosphere of 100-220 deg.C or passed between compression rollers of the same temperature in a drawn state and beaten after subjected to the drawing and heat treatment to obtain the objective short fibers having 0.1-100 μm thickness distribution and 0.1-100 mm length distribution.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention uses an acrylonitrile polymer (hereinafter abbreviated as PAN) and has a highly oriented new pulp-like short fiber having a highly molecularly oriented fiber structure without a general spinning process. It relates to a method for producing fibers.

[0002]

2. Description of the Related Art Acrylic fibers have come into the spotlight not only for clothing, but also as industrial materials such as asbestos substitute fibers, heat-retaining heat-resistant fibers, and cement-reinforcing fibers. The fibers used for such industrial materials are manufactured in the form of short fibers. Conventionally, long fibers have been manufactured through solution spinning and drawing steps using a solvent, and stapled short fibers have been obtained by cutting the long fibers. In such a conventional short fiber manufacturing method, solvent extraction, recovery, and
A complicated process such as refining is indispensable, resulting in a large economical burden and also causing a pollution problem.

Further, in the conventional production of acrylic fibers, it has not been possible to obtain fibers having a molecular orientation without going through a filament spinning through fine pores and a drawing process at a high magnification. Further, in the production of pulp fibers having a molecular orientation, a stock solution preparation in which PAN is dissolved in a solvent, spinning,
It could be produced only by a complicated method involving many steps such as solidification, solvent removal and recovery, stretching, cutting, and fibrillation.

US Pat. No. 2,585,444 discloses a molten fluid prepared by heating a water-containing material obtained by mixing PAN and 30% to 85% by weight of water to a melting temperature or higher. From this, it is described that PAN fibers are produced by a melt spinning method. US Pat. No. 3,896,20
No. 4 and 3,984,601 describe mixing PAN with about 20% to 30% water by weight to give 170
It is described that an amorphous melt obtained by heating at a temperature of from ℃ to 205 ℃ is spun and stretched 5 times or more to produce a fiber.

In US Pat. Nos. 3,991,153 and 4,163,770, a PAN-hydrate containing a mixture of 10% to 40% by weight of water has a melting temperature above the melting temperature.
That is, it is described that the melt is spun at a temperature of forming an amorphous single phase or more, and the injected filament is drawn 25 to 150 times in a pressure chamber to produce a fiber.

US Pat. Nos. 3,402,231, 3,
In 774,387 and 3,873,508, an equal amount or more of water is added to PAN to form a melt at a temperature of about 200 ° C., and the melt is spun to produce pulp fibers. Is described. However, in order to obtain a melt at a high temperature by using an excessive amount of water, the PAN filament spun by this seems to have formed fibers externally, but in reality, the orientation of molecular chains and the fiber structure are It is just a non-oriented continuous foam that does not form any.

As described above, in the conventional melt-spinning technique of PAN-hydrated material, an excessive amount of water is used, the temperature is raised to a temperature higher than the melting temperature, or the content of the comonomer is increased. This is a method of producing fibers from an amorphous melt through a spinning process to form filaments and stretching the filaments at a high magnification, for example, 5 to 30 times.

[0008]

DISCLOSURE OF THE INVENTION The object of the present invention is to eliminate the drawbacks in the conventional production of acrylic short fibers, and to use them as industrial materials such as asbestos substitute fibers, heat insulating heat resistant fibers and cement reinforcing fibers, as well as paper. The purpose of the present invention is to provide a new pulp-like acrylic short fiber that can be used as a manufacturing pulp.

That is, it is an object of the present invention to provide a new method for producing a non-spun highly oriented acrylic short fiber having a highly molecularly oriented fiber structure without performing a spinning step or a high-stretching step of the prior art. A pulp-like short fiber that simplifies various steps of a complicated pulp-like short fiber such as a stock solution preparation process for dissolving PAN in a solvent, a spinning process, a solidification process, a solvent removal and recovery process, a drawing process, and a fibrillation process. It is to provide a new manufacturing method.

[0010]

The present invention provides a weight ratio of 70
% Or more acrylonitrile and 30% or less by weight of a copolymerizable monomer are polymerized, and the viscosity average molecular weight is 1
A mixture of acrylonitrile homopolymer or copolymer of between 10,000 and 600,000 and 5% to 100% by weight of water of the above polymer is heated above the melting temperature under sealing. After forming an amorphous melt, cooling it to a temperature between the melting temperature and the solidifying temperature to obtain a quasi-crystalline melt phase, then extruding this into the external environment, and arranging and stacking plate-like fibrils etc. An extrudate having a cross-sectional structure that was formed and having a fibrous crystal structure and an orientation degree of 70% or more in an X-ray diffraction pattern was obtained.
It is characterized in that it is stretched in a gas atmosphere maintained at 0 ° C., or is passed in a tension state between compression rollers at the temperature, stretched and heat treated, and then mechanically beaten.
Thickness distribution from 0.1 μm to 100 μm and 0.1 mm
Is a method for producing pulp-like short fibers having a highly oriented fibril structure and having a distribution of a length of 1 to 100 mm.

As shown in FIG. 1, the two-component system of PAN and water (hereinafter abbreviated as PAN / H ₂ O) has a melting temperature (T
_m ) absorbs the heat of fusion, then forms an amorphous single-phase melt, and even if cooled below the melting temperature, crystallization does not occur up to a certain temperature range (OR), maintaining a supercooled molten state Then, when cooled below the solidification temperature (T _c ), PAN crystallizes and returns to its original state. However, PAN /
When an H ₂ O melt is kept in a supercooled state, a kind of quasi-crystal that has a specific molecular order similar to that of liquid crystal by joining together PAN and water in a single phase, unlike an amorphous high-temperature melt To form a phase.

As described above, it was first discovered by the present inventors that a mixture of PAN and water forms a molten quasi-crystalline phase similar to liquid crystal at a temperature below the melting temperature. This is due to the surprising phenomenon that the molecules are extremely easily oriented when extruded at a temperature between the melting temperature and the solidifying temperature as shown in FIG. In such a melted quasicrystalline phase, it is presumed that the PAN molecular chain forms a fine unit ordered phase having a linear phase molecular order together with water molecules. Since the PAN chains in the melted quasicrystal have the property of spontaneously orienting, they can very easily form a highly oriented fiber structure if they are given a slight directional shear force by a mechanical extrusion operation. .. That is, when the molten quasi-crystalline phase is extruded, the PAN molecular chains of the linear phase are laterally approaching each other while expelling the contained water out of the system and automatically forming a fiber structure. A highly oriented fiber structure is obtained without a separate drawing step.

In the present invention, PAN is mixed with an appropriate amount of water and heated in a sealed state to obtain an amorphous PAN / H.
After making the ₂ O melt, cool this amorphous melt,
Between the melting temperature and the solidifying temperature, a supercooled melt of a melted quasicrystalline phase having a molecular order similar to that of liquid crystal is prepared and extruded through an extrusion port of an appropriate standard, and simultaneously with the formation of the fiber structure, water is formed. Is automatically discharged and solidified to obtain a highly oriented extrudate in which plate-like fibrils are arranged and laminated side by side, and the extrudate is further stretched and heat-treated, and the obtained fiber is cut into a suitable length, beaten, and pulped. Manufacture short fibers.

In the present invention, the PAN / H ₂ O melt is made into a melted quasicrystalline phase having a molecular order similar to that of a liquid crystal, which cannot be predicted at all in the prior art. It was possible to manufacture a new fiber that has never been manufactured by using a new method, which is significantly different from the existing method. When a melted quasi-crystalline phase is used, when it is extruded in a tape shape through an extrusion port with a large cross-sectional area, the molecular chains can be easily oriented even with a small directional shearing force, so the molecular orientation is much higher than that of highly drawn fiber. It is possible to produce fibers having properties.

PAN in the present invention means an acrylonitrile homopolymer and a copolymer of acrylonitrile and one or more copolymerizable monomers. The composition of the copolymer is 70% or more by weight of acrylonitrile,
The copolymerizable monomer is 30% or less by weight, and more preferably 85% or more by weight of acrylonitrile.
The copolymerizable monomer is 15% or less by weight.

The copolymerizable monomers include methyl acrylate, methyl methacrylate, ethyl acrylate, chloroacrylic acid, ethyl methacrylate, acrylic acid, methacrylic acid, acrylamide, methacrylamide, butyl acrylate, methacrylonitrile, butyl methacrylate, Vinyl acetate, vinyl chloride,
Vinyl bromide, vinyl fluoride, vinylidene chloride, vinylidene bromide, allyl chloride,
Methyl vinyl ketone, vinyl formate, vinyl chloroacetate, vinyl propionate, styrene, vinyl stearate, vinyl benzoate, vinyl pyrrolidone, vinyl piperidine, 4-vinyl pyridine, 2-vinyl pyridine, N-vinyl phthalimide, N-vinyl. Succinimide, methyl malonate, N-vinylcarbazole, methyl vinyl ether, itaconic acid, vinylsulfonic acid, styrenesulfonic acid, allylsulfonic acid, methallylsulfonic acid, vinylpyran, 2-methyl-5-vinylpyridine, vinylnaphthalene, itaconic acid Ester, chlorostyrene, vinyl sulfonate, styrene sulfonate, allyl sulfonate, methallyl sulfonate, vinylidene fluoride, 1-chloro-2-bromoethylene, alphamethyl Styrene, ethylene, propylene, etc., can be cited for addition polymerization monomer having a double bond of ethylene units.

The molecular weight of the PAN, N, using N- dimethylformamide solvent, was determined as an absolute viscosity ([eta]) measured by the viscosity-average molecular weight than the following relation (M _V) (T.Shibukawa Etc., Journal of Polymer Science, Part
Al, Vol.6, 147-159, 1968).

[Η] = 3.35 × 10 ⁻⁴ M _V ^0.72 Absolute viscosity was measured at 30 ° C. by dissolving PAN in N, N-dimethylformamide. The molecular weight of the acrylonitrile polymer in the present invention is 10,000 to 600,000 as a viscosity average molecular weight converted from absolute viscosity.
Has a value between and more preferably between 50,000 and 35
It has a value between 10,000.

PAN using a differential scanning calorimeter (DSC)
-A phase change phenomenon was measured with changes in water content, temperature and PAN component of the water-containing material. Large-capacity pressure-resistant capsule (Perkin-Elmer part) that is completely sealed and can withstand high pressure.
319-0128) and used for heating and cooling PA
A melting endothermic peak and a solidification exothermic peak of the N-hydrated product were obtained, respectively.

In FIG. 1, the apex of the endothermic peak shows the melting temperature (T _m ) and the apex of the exothermic peak shows the solidifying temperature (T _c ), and the temperature range (OR) between the melting temperature and the solidifying temperature is the melting level. The region where the crystal phase is formed is shown. FIG. 3 illustrates a temperature range in which a molten quasi-crystalline phase is formed according to changes in water content. FIG. 5 is a diagrammatic representation of an example of the area change due to the PAN component. 2 and 4 use PAN containing 89.2% acrylonitrile and 10.8% methacrylate by weight, according to the examples shown in FIGS. 1 and 3, respectively, and FIG. 2 shows 20% by weight. FIG. 4 shows a temperature range in which a molten quasi-crystal phase is formed when the water content is changed from 5% to 50% by weight.

When a water-containing substance obtained by mixing PAN with an appropriate amount of water is placed in a pressure vessel and heated to a temperature higher than the melting temperature, the polymer associates with water under the steam pressure at that temperature to cause PAN / H ₂
Create an O melt. At this time, the heating temperature may be equal to or higher than the melting temperature (T _m ) shown in FIG. 1, and the pressurized state may be maintained by injecting an inert gas such as nitrogen or argon. The melt produced here is a disordered amorphous melt. When this amorphous melt is cooled and maintained at a temperature between the melting temperature and the solidifying temperature shown in FIG. 3, it becomes a supercooled melt having a melted quasicrystalline phase having characteristics similar to those of liquid crystals.

The molten quasi-crystalline phase, which is at a temperature lower than the melting temperature, does not solidify and forms a kind of supercooled melt existing as a fluid, which is not a disordered amorphous form but an ordered phase having a molecular order. is doing. In this ordered phase, the linear PAN molecular chains are arranged in parallel due to the interaction between the PAN molecular chain and water, and it has a spontaneous molecular orientation characteristic as if it were a liquid crystal. That is, as shown in FIG. 6, an extrudate extruded at a high temperature to form an amorphous melt is obtained as a substantially unoriented product having an orientation degree of about 50% described later, but it is extruded at a temperature lower than that of the amorphous melt. The extrudate thus obtained exhibits a high degree of orientation with a degree of orientation of 80% or more even in the same extrusion operation.

The temperature range in which the molten quasi-crystalline phase having such a molecular order can be formed varies depending on the acrylonitrile content of PAN as shown in FIG. 5 or the water content as shown in FIG. It belongs to the region between the melting temperature and the solidifying temperature shown in FIG.

When the PAN / H ₂ O melt is manufactured, the pressure applied to the pressure vessel may be the generated steam pressure with temperature or a pressure of about 1 to 50 atmospheres. Water content in the melt is 5% by weight
To 100% is preferred, more preferably between 10% and 50%.

In a disordered amorphous PAN / H ₂ O melt, the individual PAN molecular chains move more freely, so that not only the molecular chains are irregularly aggregated, but also between the molecular chains. It also has no order. Once this amorphous melt has cooled and is within the proper temperature range, PAN
The activity of each molecular chain is suppressed by the molecular attractive force between the molecular chain and water, and the molecular chains form a linear conformation while being constrained and are aligned in parallel with other peripheral molecular chains, and the distance between them is large. Creates a molten quasi-crystalline phase that maintains

In the molten quasi-crystal phase thus produced, it is difficult for each molecular chain to individually act because the PAN molecular chains maintain the order between the molecular chains. However, when the entire molecular chain forming the ordered phase is moved in a certain direction, the three-dimensional orientation structure is maintained as it is, as shown in FIG. 7, and then, as shown in FIG. The chains align in a certain direction and solidify. In this way fibers with a high degree of molecular orientation can be produced very easily.

That is, FIG. 7 shows a structure in which acrylonitrile polymer chains form a three-dimensional molecular order by interaction with water molecules in a molten state, and FIG. 8 shows a structure after extrusion solidification.
FIG. 2 is a model of a structure in which acrylonitrile polymer chains form a linear conformation plate-like fibril when a fiber is formed. A polymer chain extends in the direction of arrow "C", van der Waals force acts in the direction of arrow "V", and hydrogen bonding force acts in the direction of arrow "H", forming fibers. At this time, it is shown that water escapes and shrinks, and after the fiber formation, the dipole attractive force between the nitrile groups acts in the arrow “D” direction instead of the hydrogen bonding force.

However, in the amorphous melt, PA
Since each N molecular chain moves freely, it is not only possible to maintain the order between the molecular chains, but also the molecular chains themselves freely aggregate and can be arranged in a certain direction. It is impossible.

In the present invention, since the supercooled melt of the molten quasi-crystal phase has a spontaneous molecular orientation characteristic as if it were a liquid crystal, the PAN molecular chain can be obtained by simple extrusion using a piston type extruder. Form a highly oriented fiber structure,
A highly oriented extrudate having a cross-sectional structure in which plate-like fibrils are laminated side by side.

As the extruder, a screw type extruder or the like can be used in addition to the piston type extruder, and a slit die, a tube die, an arc die or the like can be freely used as the extrusion port, and the thickness vs. length can be used. Is 1 or more, and the larger this ratio, the more effective it is to obtain a highly oriented extrudate. The extrusion temperature is maintained at a constant temperature between the melting temperature and the solidification temperature of the PAN-hydrate. Extrusion conditions are such that the internal pressure is maintained at least at the generated steam pressure or higher, in a gas of less than 100 ° C. and 5 atm or less, in a natural steam pressure atmosphere of 100 ° C. to 150 ° C., or in a normal temperature and normal pressure and air atmosphere for 1 second. It is extruded into the external environment at a discharge speed of 1 mm or more per roll, and the continuous extrudate is wound at a linear velocity higher than the discharge speed. At this time, in order to increase the extrusion speed, a higher internal pressure must be applied to increase the winding speed. The ratio of the discharge speed to the winding speed is 1 or more, and increasing the ratio is advantageous for improving the orientation degree of the extrudate.

In order to produce an extrudate having a dense structure with further improved mechanical properties, a vertical tube filled with a low melting point, high specific gravity molten metal made of easy-melting metal is connected to the extrusion port. Pass it through and apply a pressure of 5 atm or less. Thus, the method of limiting the space through which water escapes by the pressure of the molten metal having a large specific gravity is also effective. Here, the length of the vertical tube is adjusted according to the required pressure, and as an easy fusion metal packed in the vertical tube, for example, B
i (50%) / Pb (31%) / Sn (19%) or Bi (50%) / Pb (24%) / Sn (14%)
/ Cd (12%) composition is 100 ℃
An alloy that is less than is used.

By extruding and solidifying the molten quasicrystalline phase, a tape-shaped extrudate composed of a fine fiber bundle is produced. In this product, the fibrils are arranged in the extrusion direction, and as shown in the scanning electron micrograph of FIG. 9, the plate-like fibrils are arranged in the cross section in a space where water is separated and removed, that is, in a dehydration space. Each of the fibrils has an internal structure in which the fibrils are separated into microfibrils in a cross-sectional structure in which the layers are arranged and laminated and a longitudinal cross-section is formed.

Here, the fibril has a thickness of 1 μm to 10 μm.
It has a plate shape of μm, and one fibril has a thickness of 0.01μ.
Micro fibrils of m to 1.0 μm are densely gathered and configured. Furthermore, fibrils can be separated into individual microfibrils as shown in the model of FIG.
The separated microfibrils are the smallest fiber unit.

The microstructure of fibrils and microfibrils was confirmed to have fibrous crystals and a highly oriented structure from the photograph of the diffraction pattern of the tape-shaped extruded product of FIG. 11 by X-ray diffraction. The degree of orientation is the main diffraction peak position in the equatorial direction (2θ = 16.
The full width at half maximum (OA) of the diffraction intensity scanned in the meridian direction at 2 ° is 70% or more from the value converted according to the following formula.

Orientation degree (%) = (180-OA) / 180 × 100 FIG. 6 shows that the PAN / H ₂ O melt was extruded at each temperature under the same extruder and the same extrusion conditions while changing only the temperature. Another extrudate was obtained, and the degree of orientation of this extrudate was measured by X-ray diffraction to show the change in the degree of orientation depending on the extrusion temperature. According to this, it is shown that, in the temperature range where the molten quasi-crystalline phase of the present invention is formed, the PAN molecular chain can be easily highly oriented even with a small directional shearing force generated by extrusion. However, it is shown that molecular orientation hardly occurs at the high temperature at which the amorphous melt is formed.

In order to further improve the degree of orientation of the highly oriented extrudate, the continuous extrudate is treated at 100 ° C to 220 ° C.
Stretching heat treatment is carried out by pulling in a gas atmosphere maintained at a temperature of ° C or by passing between rollers at a temperature applied with a compressive force in a tensioned state. Examples of the high temperature gas atmosphere include PAN such as water vapor, air, nitrogen and argon.
And the gas that causes almost no chemical reaction. The preferred stretching heat treatment temperature is 120 to 200 ° C. In the stretching heat treatment process, 5% to 10% of the initial length
An extrudate is produced that is 0% stretched and further develops a fibril structure with improved mechanical strength. As a result of analyzing the X-ray diffraction pattern of the continuous extruded product subjected to the stretching heat treatment, the orientation degree was further improved as compared with that before the stretching heat treatment, and the tensile strength and the elastic modulus were also improved by the stretching heat treatment.

If the continuous extrudate subjected to the stretching heat treatment is cut to an arbitrary length and beaten, a pulp-like fiber as shown in the scanning electron micrograph of FIG. 13 is produced. According to the cutting length and the beating condition, Fibers of various sizes can be obtained.

The pulp-like short fibers are composed of fibrils and microfibrils having a highly oriented fiber structure, have an almost irregular elliptical cross section, and have a large number of cracked gaps and branches on the side surface. The size of the fibers is 0.1 μm to 100 μm in thickness and 0.1 m in length.
It is from m to 100 mm. The individual fibers are composed of plate-like fibrils having a thickness of 1 μm to 10 μm and microfibrils having a thickness of 0.01 μm to 1.0 μm. The fine structure of pulp-like short fibers is determined by transmission electron microscopy (TEM).
Shows a fibrous crystal and highly oriented structure as in the tape-shaped extrudate before beating, as confirmed by electron diffraction pattern.

[0039]

EXAMPLES The method for producing the fiber of the present invention will be described in more detail below with reference to examples, but the present invention is not limited thereto.

Example 1 A chemical composition of 92.8% acrylonitrile and 7.2% methyl acrylate was provided in a cylinder of an extruder which was composed of a cylinder, a piston, and a slit die type extrusion port and which was capable of being closed and kept warm. The viscosity average molecular weight is 1
A mixture of 100 g of 02,000 acrylonitrile copolymer and 22 g of water was introduced, heated to 175 ° C. under a pressure of 5 kg / cm ² and completely melted, and then the temperature was lowered to 148 ° C. Keeping the condition as it is, operate the piston and apply a pressure of 60 kg / cm ² ,
It was extruded through a slit die having a width / length of 0.25 mm / 20 mm / 3 mm into a normal temperature and normal pressure atmosphere, and a tape-shaped continuous extrudate was wound at a speed of 2 m per minute.

The structure of the manufactured extrudate is observed by a scanning electron microscope, and a cross-sectional structure in which plate-like fibrils having a thickness of 1 μm to 10 μm are stacked in parallel with each other across a dehydration space, and each fibril has a thickness of 0. X has an internal structure separated into microfibrils of between 0.01 μm and 1.0 μm, and X
According to the line analysis, the tape extrudate has fibrous crystals,
The degree of molecular orientation was 89%. The continuous extrusion tape was finely separated along the length direction to obtain long fibers, and the mechanical properties were measured. As a result, it was found that the tensile strength was 4.5 g / denier, the elongation was 11%, the tensile modulus was 67 g / The value of denier was shown. The tape-shaped continuous extrudate was maintained at 150 ° C. and passed under tension between rollers to which a compressive force was applied, and subjected to a 30% stretching heat treatment.

According to X-ray analysis, this stretch-heat treated tape-shaped extrudate had fibrous crystals and showed a degree of molecular orientation of 91%. The continuous extruded tape subjected to the drawing heat treatment was finely separated along the length direction to obtain long fibers, and the mechanical properties were measured. As a result, it was found that the tensile strength was 5.7 g / denier, the elongation was 10%, the tensile elasticity was 10%. The rate was 86 g / value.

The tape-shaped continuous extrudate subjected to the drawing heat treatment was
It was cut to a length of 0 mm and beaten with a beater to produce pulp-like short fibers. The short fibers produced are from 0.1 μm to 2
It had a thickness distribution of 0 μm and a length distribution of 1 mm to 20 mm.

Example 2 100 g of an acrylonitrile homopolymer having a viscosity average molecular weight of 93,000 and 30 g of water were placed in a cylinder of an extruder which is composed of a cylinder, a piston and a slit die type extrusion port and which can be closed and kept warm by heating. The mixed mixture was introduced, heated to 205 ° C under a pressure of 5 kg / cm ² to completely melt it, and then the temperature was lowered to 178 ° C and maintained, and the piston was operated to 70 kg / cm ²
Is applied, the thickness / width / length is 0.35mm / 20m
It was extruded through a slit die of m / 4 mm into an atmosphere of normal temperature and normal pressure, and a continuous tape-shaped extrudate was wound at a speed of 1.5 m per minute. This continuous extrudate was maintained at 170 ° C. and passed under tension between rollers to which a compressive force was applied, and subjected to a 25% stretching heat treatment.

According to X-ray analysis, the stretch-heat treated tape-shaped extrudate had fibrous crystals and showed a degree of molecular orientation of 90%. The continuous extruded tape subjected to the stretching heat treatment was finely separated along the length direction to obtain long fibers, and the mechanical properties were measured. As a result, it was found that the tensile strength was 6.0 g / denier, the elongation was 9%, the tensile elasticity was 9%. The rate was 93 g / denier.

The tape-shaped continuous extrudate subjected to the stretching heat treatment was applied to 15
The pulp-like short fiber was manufactured by cutting into a length of mm and beating with a beater. The short fibers produced are from 0.1 μm to 20
It had a thickness distribution of μm and a length distribution of 1 mm to 15 mm.

Example 3 A chemical composition of 94.2% acrylonitrile and 5.8% methyl acrylate was placed in a cylinder of an extruder which was composed of a cylinder, a piston, and a slit die type extrusion port and which was capable of being closed and heated. The viscosity average molecular weight is 1
A mixture of 100 g of 78,000 acrylonitrile copolymer and 25 g of water was introduced, heated to 180 ° C. under a pressure of 5 kg / cm ² and completely melted, and then the temperature was lowered to 155 ° C. Keeping the condition as it is, operate the piston and apply a pressure of 60 kg / cm ² ,
Extruded through a slit die with a width / length of 0.25 mm / 20 mm / 3 mm, and tape-shaped continuous extrudate at 2 per minute.
It was wound up at a speed of m. This continuous extrudate was maintained at 160 ° C. and passed under tension between rollers to which a compressive force was applied, and subjected to 25% stretching heat treatment.

According to X-ray analysis, the stretch-heat treated tape-shaped extrudate had fibrous crystals and showed a degree of molecular orientation of 91%. This extruded tape is finely separated into long fibers along the length direction, and the result of measuring the mechanical properties,
The tensile strength was 6.1 g / denier, the elongation was 10%, and the tensile elastic modulus was 97 g / denier.

The stretched and heat-treated tape-shaped continuous extrudate 20
The pulp-like short fiber was manufactured by cutting into a length of mm and beating with a beater. The short fibers produced are from 0.1 μm to 20
It had a thickness distribution of μm and a length distribution of 1 mm to 20 mm.

Example 4 A chemical composition of 88.6% acrylonitrile and 11.4% methyl acrylate was used in a cylinder of an extruder which was composed of a cylinder, a piston, and a slit die type extrusion port, and which was capable of being closed and heated. Then, a mixture obtained by mixing 100 g of an acrylonitrile copolymer having a viscosity average molecular weight of 215,000 and 25 g of water was introduced, heated to 175 ° C. under a pressure of 5 kg / cm ² and completely melted, and then 145 Reduce the temperature to ℃, maintain it as it is, operate the piston and apply a pressure of 70 kg / cm ² ,
Extrusion through a slit die having a width / length of 0.40 mm / 20 mm / 4 mm to give a tape-shaped continuous extrudate 1 per minute
It was wound up at a speed of m. This continuous extrudate was maintained at 140 ° C. and passed under tension between rollers to which a compressive force was applied, and subjected to a 35% stretching heat treatment.

According to X-ray analysis, the stretch-heat treated tape-shaped extrudate had fibrous crystals and exhibited a degree of molecular orientation of 89%. The continuous extruded tape subjected to the stretching heat treatment was finely separated along the length direction to obtain long fibers, and the mechanical properties were measured. As a result, the tensile strength was 6.3 g / denier, the elongation was 10%, and the tensile elastic modulus was 84 g / denier. The value of was shown.

This stretch-heat treated tape-shaped continuous extrudate was cut into a length of 10 mm and beaten with a beater to produce pulp-like short fibers. The short fibers produced are 0.1 μm
With a thickness distribution of 1 to 30 μm and a length distribution of 1 mm to 10 mm.

Example 5 A chemical composition of 94.8% acrylonitrile and 5.2% vinyl acetate was used in a cylinder of an extruder which was composed of a cylinder, a piston, and a slit die type extrusion port and which was capable of being closed and heated. And the viscosity average molecular weight is 9
100 g of 7,000 acrylonitrile copolymer and water 2
After introducing a mixture obtained by mixing 6 g and heating the mixture to 180 ° C. under a pressure of 5 kg / cm ² to completely melt it,
The temperature was lowered to 155 ° C and kept as it was, and the piston was operated to apply a pressure of 65 kg / cm ² to the thickness / width /
Extrusion through a slit die having a length of 0.30 mm / 15 mm / 4 mm to give a tape-shaped continuous extrudate at 1.8 per minute.
It was wound up at a speed of m. This continuous extrudate was maintained at 160 ° C. and passed under tension between rollers to which a compressive force was applied, and subjected to a stretching heat treatment by 27%.

According to X-ray analysis, the stretch-heat treated tape-shaped extrudate had fibrous crystals and showed a degree of molecular orientation of 90%. This stretch-heat treated continuous extruded tape was finely separated along the length direction to obtain long fibers, and the mechanical properties were measured. As a result, the tensile strength was 5.8 g / denier, the elongation was 10%, and the tensile elastic modulus was 88 g / denier. The value of was shown.

The tape-shaped continuous extrudate subjected to the drawing heat treatment was cut into a length of 10 mm and beaten with a beater to produce pulp-like short fibers. The short fibers produced had a thickness distribution of 0.1 μm to 30 μm and a length distribution of 1 mm to 10 mm.

Example 6 A chemical composition of 83.8% acrylonitrile and 16.2% vinyl acetate was placed in a cylinder of an extruder which was composed of a cylinder, a piston and a slit die type extrusion port and was capable of sealing and keeping heat. The viscosity average molecular weight is 1
A mixture of 100 g of 76,000 acrylonitrile copolymer and 20 g of water was introduced, heated to 165 ° C. under a pressure of 5 kg / cm ² and completely melted, and then cooled to 135 ° C., Maintaining the pressure of 55 kg / cm ² by actuating the piston and extruding through a slit die having a thickness / width / length of 0.25 mm / 20 mm / 3 mm, a tape-shaped continuous extrudate of 2.4 m / min. It was wound up at the speed of. This continuous extrudate was maintained at 140 ° C. and passed under tension between rollers to which a compression force was applied, and subjected to a 43% stretching heat treatment.

According to X-ray analysis, the stretch-heat treated tape-shaped extrudate had fibrous crystals and exhibited a degree of molecular orientation of 86%. This stretch-heat treated continuous extruded tape was finely separated along the length direction to obtain long fibers, and the mechanical properties were measured. As a result, the tensile strength was 5.3 g / denier, the elongation was 12%, the tensile modulus was 72 g / denier. The value of was shown.

The stretched and heat-treated tape-shaped continuous extrudate was cut into a length of 15 mm and beaten with a beater to produce pulp-like short fibers. The short fibers produced had a thickness distribution of 0.1 μm to 40 μm and a length distribution of 1 mm to 15 mm.

Example 7 89.5% of acrylonitrile and 10.5 of styrene were placed in the cylinder of an extruder which was composed of a cylinder, a piston and a slit die type extrusion port and which was capable of being closed and kept warm by heating.
% Chemical composition with a viscosity average molecular weight of 126,0
A mixture of 100 g of acrylonitrile copolymer of 00 and 21 g of water was introduced, heated to 170 ° C. while being pressurized to 5 kg / cm ² , and completely melted.
Lower the temperature to ℃, maintain it, and operate the piston
0.3 kg in thickness / width / length by applying pressure of kg / cm ^2.
Extruded through m / 20mm / 4mm slit die,
The tape-shaped continuous extrudate was wound at a speed of 2 m / min. This continuous extrudate was maintained at 155 ° C. and passed under tension between rollers to which a compressive force was applied, and subjected to a 30% stretching heat treatment.

According to X-ray analysis, this stretch-heat treated tape-shaped extrudate had fibrous crystals and showed a degree of molecular orientation of 87%. The continuous extruded tape was finely separated along the length direction to obtain long fibers, and the mechanical properties were measured. As a result, the tensile strength was 4.8 g / denier, the elongation was 12%, and the tensile elastic modulus was 82 g / denier. Indicated.

Example 8 A chemical composition of 87.1% acrylonitrile and 12.9% methyl methacrylate was placed in a cylinder of an extruder which was composed of a cylinder, a piston, and a slit die type extrusion port and which was capable of being closed and kept warm by heating. Acrylonitrile copolymer 100 having a viscosity average molecular weight of 112,000
g and 18 g of water were introduced into the mixture, and 5 kg / cm
^After pressurizing to ² and heating to 170 ℃ to completely melt, lower the temperature to 140 ℃, maintain it as it is, operate the piston to apply a pressure of 50 kg / cm ² , thickness / width / It was extruded through a slit die having a length of 0.20 mm / 20 mm / 3 mm into an atmosphere at normal temperature and normal pressure, and the tape-shaped continuous extrudate was wound at a speed of 2 m per minute.
This continuous extrudate was maintained at 145 ° C. and passed under tension between rollers to which a compression force was applied, and subjected to a 40% stretching heat treatment.

According to X-ray analysis, the stretch-heat treated tape-shaped extrudate had fibrous crystals and showed a degree of orientation of 90%. The continuous extruded tape which had been subjected to the stretching heat treatment was finely separated along the length direction to obtain long fibers, and the mechanical properties were measured. As a result, the tensile strength was 6.3 g / denier and the elongation was 10
%, And the tensile modulus of elasticity was 83 g / denier.

Comparative Example 1 For the purpose of a comparative test, a cylinder of an extruder similar to that of Example 1 was used, which had a chemical composition of 92.8% acrylonitrile and 7.2% methyl acrylate and had a viscosity average molecular weight of 102, 000 acrylonitrile copolymer 100g
And a mixture of 22 g of water and 5 g / cm ² were introduced.
After heating up to 175 ° C and melting it completely, press the piston to operate 60kg / cm ²
Is applied, the thickness / width / length is 0.25mm / 20m
It was extruded into the atmosphere of normal temperature and normal pressure through a slit die of m / 3 mm to obtain a continuous extrudate with remarkable foaming. This foam did not show any orientation in the X-ray diffraction pattern and could not produce short pulp fibers.

Comparative Example 2 For the purpose of a comparative test, the composition of the chemical composition of acrylonitrile 92.8% and methyl acrylate 7.2% was used in a cylinder of an extruder similar to that of Example 1, and a viscosity average molecular weight of 102, 000 acrylonitrile copolymer 100g
And a mixture of 22 g of water and 5 g / cm ² were introduced.
After heating up to 175 ° C and completely melting it, press the piston to operate 30kg / cm ²
Is applied, the thickness / width / length is 0.25mm / 20m
2kg / cm ^{2 at} room temperature through m / 3mm slit die
Extruded into the pressure chamber of the
It was wound at a speed of 5 m per minute. According to X-ray analysis, this tape-shaped extrudate showed a degree of orientation of 56%, but pulp-like short fibers could not be produced.

[0065]

As described above, in the production method of the present invention, an epoch-making simple process in which PAN is mixed with a small amount of water as a eutectic, melt-extruded, and then the extrudate is stretched and heat-treated. As a result of producing highly oriented pulp-like acrylic short fibers, not only is the production cost significantly reduced compared to existing methods, but there is also no problem of pollution by organic solvents, and the short fibers themselves are composed of highly oriented fibrils. The fiber produced by this method has excellent physical properties due to a high degree of molecular orientation,
Since it is composed of microfibrils, it has a very large surface area and has an irregular cross-sectional structure, and therefore has very good binding properties with other substances.

Thus, the pulp-like short fibers produced by the method of the present invention can be advantageously used not only as an industrial material such as asbestos substitute fiber, heat-resistant heat-resistant fiber, cement reinforcing fiber, etc., but also as a pulp material. Since it has the conditions and can be produced at a low cost by a simple process, it can be advantageously used as a raw material for paper instead of natural pulp. Further, this pulp-like short fiber is composed of fine fibrils, and has an irregular elliptical cross section and a large number of cracked gaps and branches on the side surface, so that it has advantageous properties as a pulp for paper. Have.

[Brief description of drawings]

FIG. 1 is a graph showing typical melting endothermic temperature (T _m ) and solidification exothermic temperature (T _c ) measured by a differential scanning calorimeter (DSC) of an acrylonitrile polymer hydrate.

FIG. 2 shows, as an example of FIG. 1, an acrylonitrile polymer containing 89.2% of acrylonitrile and 10.8% of methyl acrylate in a weight ratio, and 20% of water mixed with the melting temperature (T _m ) of the water-containing substance and solidification thereof. It is a graph which showed temperature ( _Tc ).

FIG. 3 is a graph showing typical changes in melting temperature (T _m ) and solidification temperature (T _c ) depending on the water content of the water-containing substance of the acrylonitrile polymer.

FIG. 4 shows, as an example of FIG. 3, a melting temperature (T _m ) and a solidification temperature (T _m ) of a water content of a water content of an acrylonitrile polymer containing 89.2% of acrylonitrile and 10.8% of methyl acrylate in a weight ratio. It is a graph which showed change of _c ).

FIG. 5 is a graph showing changes in melting temperature (T _m ) and solidification temperature (T _c ) due to changes in the content of methyl acrylate in the hydrous acrylonitrile copolymer.

FIG. 6 is a graph showing changes in the degree of orientation of an extrudate of a hydrous acrylonitrile polymer depending on the extrusion temperature of the melt.

FIG. 7 is a structural model diagram showing tertiary molecular order due to interaction between acrylonitrile polymer chains and water molecules in a molten state.

FIG. 8 is a structural model view in which acrylonitrile polymer chains form a linear conformation plate-like fibril when a fiber is formed after extrusion solidification.

FIG. 9 is a scanning electron micrograph of a transverse section and a longitudinal section of a tape-shaped extrudate.

FIG. 10 is a model diagram showing a cross-sectional structure and a vertical sectional structure of the tape-shaped extrudate of FIG. 9.

11 is an X-ray diffraction pattern photograph of the tape-shaped extrudate of FIG.

12 is a diffraction intensity curve diagram scanned in the meridian direction at the position of the main diffraction peak (2θ = 16.2 °) in the equatorial direction on the X-ray diffraction pattern of FIG.

FIG. 13: Beating of a tape-shaped extrudate subjected to stretching heat treatment (beati
ng) is a scanning electron micrograph of pulp-like short fibers.

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] November 10, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Brief description of the drawing

[Correction method] Change

[Correction content]

[Brief description of drawings]

FIG. 1 is a graph showing typical melting endothermic temperature (T _m ) and solidification exothermic temperature (T _c ) measured by a differential scanning calorimeter (DSC) of an acrylonitrile polymer hydrate.

FIG. 2 shows, as an example of FIG. 1, an acrylonitrile polymer containing 89.2% of acrylonitrile and 10.8% of methyl acrylate in a weight ratio, and 20% of water mixed with the melting temperature (T _m ) of the water-containing substance and solidification thereof. It is a graph which showed temperature ( _Tc ).

FIG. 3 is a graph showing typical changes in melting temperature (T _m ) and solidification temperature (T _c ) depending on the water content of the water-containing substance of the acrylonitrile polymer.

FIG. 4 shows, as an example of FIG. 3, a melting temperature (T _m ) and a solidification temperature (T _m ) of a water content of a water content of an acrylonitrile polymer containing 89.2% of acrylonitrile and 10.8% of methyl acrylate in a weight ratio. It is a graph which showed change of _c ).

FIG. 5 is a graph showing changes in melting temperature (T _m ) and solidification temperature (T _c ) due to changes in the content of methyl acrylate in the hydrous acrylonitrile copolymer.

FIG. 6 is a graph showing changes in the degree of orientation of an extrudate of a hydrous acrylonitrile polymer depending on the extrusion temperature of the melt.

FIG. 7 is a structural model diagram showing tertiary molecular order due to interaction between acrylonitrile polymer chains and water molecules in a molten state.

FIG. 8 is a structural model view in which acrylonitrile polymer chains form a linear conformation plate-like fibril when a fiber is formed after extrusion solidification.

FIG. 9 is a scanning electron micrograph of a cross section and a vertical section of a fibrous tape-shaped extrudate.

FIG. 10 is a model diagram showing a cross-sectional structure and a vertical sectional structure of the tape-shaped extrudate of FIG. 9.

11 is an X-ray diffraction pattern photograph of the tape-shaped extrudate of FIG.

12 is a diffraction intensity curve diagram scanned in the meridian direction at the position of the main diffraction peak (2θ = 16.2 °) in the equatorial direction on the X-ray diffraction pattern of FIG.

FIG. 13: Beating of a tape-shaped extrudate subjected to stretching heat treatment (beati
2 is a scanning electron micrograph showing the fiber shape of pulp-like short fibers obtained by ng).

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Lee Satoshi Zhou, No. 53, No. 53, Dong-dong, Goryeong-gu, Yangwon-gu, Seoul, Republic of Korea No. 206, 10 Korean houses 10 (72) Inventor, Min Ji-Yi No. 603, Jangxi 6-dong, Hara-gu, 120 No. 603, residential residence apartment 603 (72) Inventor ▲ Chiyo ▼ No. 1157 54, 1157 Anyang-dong, Anyang-si, Gyeonggi-do, South Korea

Claims (10)

[Claims] 1. An acrylonitrile homopolymer having a viscosity average molecular weight of 10,000 to 600,000 obtained by polymerizing 70% or more by weight of acrylonitrile and 30% or less by weight of a copolymerizable monomer. Alternatively, a mixture of a copolymer and 5% to 100% by weight of water of the above polymer is heated to a melting temperature or higher in a closed state to form an amorphous melt, which is solidified with the melting temperature. After cooling to a temperature between temperatures to obtain a quasi-crystalline molten phase, this is extruded into the external environment and has a cross-sectional structure in which plate-like fibrils and the like are aligned and laminated, and has a fibrous crystal structure in an X-ray diffraction pattern. And an extrudate having a degree of orientation of 70% or more are obtained, and the extrudate is stretched by stretching in a gas atmosphere maintained at 100 to 220 ° C. or by passing it between the compression rollers at the temperature in a stretched state. Heat treatment And then mechanically beating the pulp-like short fibers of highly oriented fibril structure having a thickness distribution of 0.1 μm to 100 μm and a length distribution of 0.1 mm to 100 mm. Manufacturing method. 2. The highly oriented fibril structure has a thickness of 0.0.
1 μm to 1.0 μm microfibrils and thickness 1
The manufacturing method according to claim 1, wherein the manufacturing method is constituted by plate-like fibrils having a size of 10 μm to 10 μm. 3. The production method according to claim 1, wherein the stretching heat treatment is performed by passing the extrudate in a tension state between compression rollers at 120 ° C. to 200 ° C. 4. The stretching heat treatment results in 5% to 100%.
The method according to claim 1, wherein the stretching is performed. 5. Extrusion into the external environment is carried out in a gas of less than 100 ° C. and 5 atm or less, in a natural steam pressure atmosphere of 100 ° C. to 150 ° C., or with a fusible alloy having a melting point of less than 100 ° C. The production method according to claim 1, wherein the production is carried out by passing through a vertical tube and applying a pressure of 5 atm or less. 6. The method according to claim 1, wherein the extrusion into the external environment is carried out at room temperature and atmospheric pressure and in an air atmosphere. 7. The mixture is used in a weight ratio of 1 to the polymer.
The method of claim 1, comprising 0% to 50% water. 8. The method according to claim 1, wherein the amorphous melt is formed in a temperature range from the melting temperature of the polymer hydrous material to 220 ° C. 9. The acrylonitrile homopolymer and copolymer have a viscosity average molecular weight of 50,000 to 350,0.
The manufacturing method according to claim 1, which is 00. 10. The acrylonitrile homopolymer and copolymer are 85% by weight or more of acrylonitrile and 1% by weight.
A composition comprising 5% or less of a copolymerizable monomer.
Manufacturing method.