JPH09291413A - Surface fibrillated fiber, fibril-containing split fiber obtained therefrom and their production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce both a surface fibrillated fiber, comprising fibrils covering most of the surfaces of main fibers in the fiber axial direction and useful as a filter medium, a sheetlike material, etc., for artificial leathers by carrying out the solution spinning of a polymer containing a sufficient amount of a cellulosic ester under specific conditions and a fibril-containing split fiber by beating the resultant surface fibrillated fiber. SOLUTION: This surface fibrillated fiber is obtained by carrying out a method for jetting a coagulant fluid for a polymer from a coagulant fluid jetting port at >=0 deg. and <90 deg. angle from the discharging line direction of a spinning solution, etc., when dissolving the polymer containing at least 30wt.% cellulosic ester in a solvent and discharging the resultant spinning solution from a discharging port for the spinning solution. The prepared surface fibrillated fiber comprises fibrils B and B', having <=2μm diameter and covering most of main fibers A in the fiber axial direction. The surface fibrillated fiber is beaten to afford a fibril-containing split fiber.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to surface fibrillated fibers, fibril-containing split fibers obtained therefrom, and a method for producing them. More specifically, a surface fibrillated fiber made of a cellulose ester polymer that can be used for a sheet material for a filtering material or artificial leather,
Also, the present invention relates to fibril-containing split fibers and a method for producing them.

[0002]

2. Description of the Related Art Ultrafine fibers and fibrillated fibers are suitably used as a raw material for obtaining a sheet-like material such as synthetic paper or non-woven fabric. Especially, it is required to have a high filtration performance with a low pressure loss in an air filter or the like. It is widely used as a base fiber for artificial leather, a cleaner for removing fine dust, and a texture of animal hair.

As such fibers, non-woven fabrics of ultra-fine fibers of polyester polymer, polypropylene and polyethylene polymer and fibrillated fibers have been proposed. These fibers are produced by the method described later, but some of them are directly formed on the non-woven fabric or are produced through a dissolution and removal step. These are composed of polyester-based polymers and polyolefin-based polymers, and have the disadvantage of poor hygroscopicity due to the nature of the polymer. In addition, fibril fibers made of aromatic polyamides and cellulose polymers have been proposed, but since the fiber form is pulp-like, base fibers for nonwoven fabrics or artificial leather such as air filters that require a high porosity are required. As a practical end. Cellulose acetate is widely used in the field of dental materials such as clothing, base materials for cigarette filters or hemostatic agents due to its excellent polymer characteristics, but the fibrillated fiber as described above and its manufacturing method have not yet been proposed. Absent.

[0004] Numerous methods have been known for producing fibrillated fibers useful as materials such as nonwoven fabrics and papers. It is well known that a flash spinning method disclosed in JP-A-40-28125 and JP-A-41-6215 is known as a method for producing a continuous yarn (plexifilament) of innumerable fibril fibers. There is. In this spinning method, a crystalline polymer solution that is at a temperature higher than the normal boiling point of the solvent and is under a high vapor pressure range or higher is generated from an appropriately shaped orifice into a low pressure range. The solvent evaporates violently and a large number of the extruded polymers are torn apart to form continuous fibril fibers. Since this method requires instantaneous evaporation of the solvent, it is necessary to use a relatively low boiling point solvent such as benzene, toluene, cyclohexane, methylene chloride, etc. It is necessary to select a polymer which forms a uniform solution with a solvent and which is a non-solvent when the solvent is extruded into the low pressure region, and the fibrillar fiber composition obtained is limited.

As an example of application of this system to a cellulose acetate polymer, there is JP-A-49-7518. The cross section of the obtained fiber is circular or elliptical, and the fibers having severe irregularities, protrusions, and tentacles on the periphery are well controlled to have an average diameter of 0.1 μm to 20 μm, and it cannot be said to be a morphology. Further, the manufacturing method also requires handling under high temperature and high pressure, and is not industrially advantageous.

As a method for producing submicron-order fibers, there is melt blown spinning that is industrialized with polyester fibers and the like. This method is a method of obtaining a submicron-order fiber by stretching, thinning, and solidifying a polymer in a molten state extruded by an extruder with a high-speed air stream, but it is premised on a polymer that melts by heat and has a melting temperature of This method cannot be applied to high-polymers and heat-modified polymers.

There is a method of producing ultrafine fibers by performing sea-island composite spinning of polymers of two components having different dissolution characteristics and eluting the island components. This method is not economical because it is necessary to elute the island component after producing the fiber. In addition, it is difficult at present to spin a precise sea-island composite fiber by solution spinning, which is a spinning method for polymer materials that do not melt by heat. JP-B-52-18291 discloses that a mixture of two or more kinds of thermoplastic resins that are hydrophobic and incompatible with each other or a mixture containing an inorganic material and an organic material is melted by heating, extruded from a slit nozzle, and stretched in one direction. Then, a method of fibrillating the chip obtained by cutting the band, which has been molecularly oriented, into a length of 3 to 50 mm by a physical external force,
A method for facilitating beating fibrillation by adding a water-soluble polymer has been proposed. The method is applicable to thermoplastic resins, and is applicable to polymers that have a relatively high melting temperature and are subject to thermal modification, such as cellulose acetate, which is the object of the present invention, and is difficult to melt-shape. It is a method that cannot be done.

Solution spinning is used as a method for producing fibrillated fibers of a polymer which is difficult to be melt-shaped. As a method of obtaining a submicron-order fiber of a polymer in which solution spinning is essential, Japanese Unexamined Patent Publication (Kokai) No. 3-130411 discloses an ultrafine fiber having a diameter of 2 μm or less and an aspect ratio of 1000 or more made of a polymer containing 85% or more acrylonitrile. Proposed. This method is a method of preparing a mixed solution of polymers having different solubilities in an extraction solvent, fiberizing the solution by a known spinning method, and then eluting one polymer to obtain ultrafine fibers. Similar to the composite spun fiber, it is not economical because it elutes and removes the polymer, and considering the recent environmental problems, it is necessary to solve the problem of recovery or disposal of the eluted polymer solution, which is an industrially advantageous method. Is hard to say.

Japanese Unexamined Patent Publication (Kokai) No. 3-104915 discloses that a stock solution in which a polymer containing acrylonitrile as a main component and having a weight average molecular weight of 300,000 or more is dissolved in an amount of 3 to 10 wt% is wet-spun.
After making it into a porous fiber, it is beaten to have a diameter of 0.5 μm.
A method for producing an acrylonitrile-based pulp having the following fibrils has been proposed. With this method, even if beaten, only a part of the fibril fiber becomes 0.5 μm or less, and the base fiber remains, which is not sufficient for applications such as filters requiring a high surface area, and is also used for artificial leather applications. In that case, the texture of the base material is deteriorated by the base fiber, which is not preferable.

[0010] As a method of obtaining fibers of a cellulosic polymer on the order of submicron diameter, fibers and industry (Vol. 48.N.
o10 (1992)) a method of beating cellulose fibers with a high-pressure homogenizer has been proposed. This method utilizes the properties of highly crystalline cellulose and beats the highly fibrillated cellulose fibers to the order of microfibrils. This method is not universal because it requires a special device for beating. Although it is applicable to cellulose, it is difficult to apply it to other useful polymers that do not melt by heat such as cellulose acetate and acrylonitrile polymers.

JP-A-2-234909 proposes a method for producing a sub-denier fiber from a liquid-repellent liquid crystal polymer. This method pushes an optically anisotropic polymer solution into a chamber, introduces a pressurized gas into the chamber, directs the gas in the chamber in the flow direction and around it while contacting the gas. And flow together through the interstitial space into the lower pressure zone, passing the stream at a velocity sufficient to break it into fibers and contact the split stream in the zone with the coagulating fluid. Is. This method is premised on a polymer solution that forms lyotropic liquid crystals,
The application range is limited, and it is necessary to pass the high-viscosity polymer solution discharged from the extrusion port further into the gap, which easily causes clogging of the gap with the polymer solution, which is not an industrially superior method.

[0012]

It has been difficult to obtain fibril-containing fibers and ultrafine fibers from a conventional production method for a polymer containing a cellulose ester. The present invention provides a surface fibrillated fiber containing a cellulose ester that can be used for a sheet material for a filter medium or artificial leather, and provides an ultrafine fiber composed of fibril-containing split fibers, and The present invention provides an industrially superior method for producing fibers.

[0013]

A first gist of the present invention is as follows.
A surface fibrillated fiber comprising a polymer containing at least 30% by weight of cellulose ester, wherein fibrils having a diameter of 2 μm or less cover most of the main fiber surface along the fiber axis direction of the main fiber. is there.

Specific examples of the cellulose ester used in the present invention include cellulose (mono) acetate, cellulose diacetate, cellulose triacetate, cellulose acetate butyrate, benzyl cellulose, or a mixture thereof. Cellulose (mono)
Acetate, cellulose diacetate and cellulose triacetate are preferably used.

The surface fibrillated fiber of the present invention comprises a main fiber A and a fibril B. As shown in FIG. 1, the fibrils B ′ branched from the fiber surface of the main fiber A and / or the fibrils B ″ completely separated from the surface of the main fiber A cover the fiber surface of the main fiber A. Further, as shown in Fig. 1, the surface fibrillated fiber of the present invention may be one in which the end portion and / or the central portion of the main fiber A is divided into fibrils, wherein the diameter is 2 µm. Meaning that the following fibril B covers the surface of the main fiber along the fiber axis direction of the main fiber A means that, in any cross section of the main fiber in the direction perpendicular to the fiber axis, as shown in FIG. A state in which a cross section of the fibril B is seen outside the surface of the main fiber, preferably.
The observed percentage of fibril cross sections in any cross section perpendicular to the main fiber axis is 90% or more. The main fiber A has a diameter of 1 μm to 100 μm, and the fibril B
Preferably has a diameter of 0.1 μm to 2 μm, and the fibrils B are covered so that the fiber surface of the main fiber A is laminated linearly or curvedly along the fiber axis.
Most of the fibrils B have a branched structure.

When the surface fibrillated fiber having such a structure is formed into a non-woven fabric or the like, it has entangled fibers of 2 μm or less, which not only imparts mechanical strength to the non-woven fabric and the like, but also increases the specific surface area and is high. Adsorption characteristics can be provided. Further, the surface fibrillated fiber can be used as a yarn having a unique "slimy" feeling by cutting it into a predetermined length and spinning, if necessary.

Further, the surface fibrillated fiber can be used as a precursor fiber of the fibril-containing split fiber. That is, the precursor fiber of the surface fibrillated fiber can be made to have various diameters infinitely by a mechanical load such as a coagulation step or by beating.

That is, the second gist of the present invention consists of a polymer containing at least 30% by weight of a cellulose ester polymer, fibrils having a diameter of 2 μm or less, and diameters of 100 μm or less, and various thicknesses infinitely. A fibril-containing split fiber characterized by comprising split fibers having an aspect ratio (l / d) of 1000 or more. Here, 1 is the fiber length, and d is the apparent diameter of the fiber. The fibril-containing split fiber of the present invention refers to a fiber in which surface fibrillated fibers are split into split fibers, and the split fibers have a diameter of 2 μm or less.
It also includes fibrils of the split fibers themselves. Therefore, when the split fibers themselves become fibrils and form an aggregate integrated with the fibrils, the diameter of the fibers is preferably 2 μm or less, and more preferably, both the fibrils and the fibers have a diameter of 1 μm or less. is there.

In the present invention, the beating degree can be arbitrarily controlled, and the precursor fiber and the beaten fiber may be mixed, and the mixing ratio thereof is not limited. By beating the precursor fiber, the fiber is further branched, a part of which is completely divided in the fiber axis direction to a fibril having a diameter of 2 μm, another part is partially divided, and another part is further divided. Fibers having various diameters in a stepless manner having a fiber diameter before being beaten. The fibers form an aggregate of fibers, some of which are continuously connected and others of which are discontinuous. Such a fiber structure can give a more suitable shape as a fiber base material provided for a nonwoven fabric or the like. Further, when the beating is continued, finally, the fibril having a diameter of 2 μm or less (preferably 1 μm or less) and the aspect ratio (l having a diameter of 5 μm or less (preferably 2 μm or less) and various thicknesses infinitely / D) forms an aggregate of fibril-containing split fibers having a ratio of 1000 or more. Further, all the fibers are divided into the diameters equivalent to the fibrils, and the fibril-like fibers having a diameter of 2 μm or less are obtained.

With respect to such a fiber, the beating condition can be changed according to the end use to obtain a fiber having a desired form.
For example, when used for sheet materials such as non-woven fabrics for air filters, it has a structure in which some of the fibers are fibrillated to give appropriate strength to the sheet, and when used for artificial leather, it has a unique animal hair texture. It is desirable that the fiber is composed of fibers that are almost 100% fibril-like in the production.

In the present invention, it is preferable to use, in addition to the cellulose ester, a polymer other than the cellulose ester, which is soluble in a solvent for dissolving the cellulose ester, in combination with the cellulose ester. Thus, by using one or more other polymers in combination, it is possible to more efficiently obtain the fiber of the present invention, and also to impart the functions (hygroscopicity, etc.) of other polymers to the cellulose ester. it can.

Examples of these other polymers include cellulose, polyacrylonitrile-based polymers, vinyl chloride,
Polyester polymer, polysulfone, etc. can be mentioned, but in order not to impair the properties of cellulose ester as a natural material, natural polymers such as cellulose and other cellulose derivatives, or acrylonitrile in terms of the texture as a fiber material. A polymer having a film forming ability such as a system polymer is preferable. For example, in the case of a combination of cellulose and cellulose acetate, a base material such as artificial leather having a texture of a natural material, a cigarette filter having an excellent adsorptivity of nicotine or tar, or a nonwoven fabric for a filter having an excellent adsorptive performance having a biodegradability function. Can be a fiber. Further, a combination of polyacrylonitrile and cellulose acetate is used as a material for artificial leather having hygroscopicity and excellent color developability and as a base fiber for a non-woven fabric having a soft texture.

The third gist of the present invention is to coagulate the coagulant fluid of the polymer when the spinning dope prepared by dissolving the polymer containing at least 30% by weight of cellulose ester in the solvent is discharged from the spinning dope discharge port. Spraying from the agent fluid jet at an angle of 0 ° or more and less than 90 ° with respect to the discharge line direction of the spinning dope, coagulating the polymer in a shear flow rate, and washing the coagulated body formed And a method for producing a surface fibrillated fiber.

In the present invention, since the coagulant fluid is jetted so that the fluid flows in the discharge line direction of the spinning dope, the angle formed by the spout line direction of the coagulant fluid and the discharge line direction of the spinning dope is 0.
It is necessary to set the angle to be not less than 90 degrees and not more than 90 degrees. When the angle between the jet line direction of the coagulant fluid and the discharge line direction of the spinning dope is within the above range, the mixed liquid of the solidified body, solvent and coagulant formed can be promptly discharged from the outlet of the mixing cell. Becomes Further, the preferable angle should be set in the range of 20 to 80 degrees, and more preferably 30 to 70 degrees. By ejecting and ejecting both solutions within this range, the spinning stock solution ejected into the mixing cell and the coagulant fluid ejected into the mixing cell are sufficiently mixed, and the spinning stock solution and the coagulant fluid are immediately mixed. It becomes a shear flow, the polymer is solidified, and it becomes possible to obtain the surface fibrillated fiber of the present invention.

When the ejection line direction of the coagulant fluid and the ejection line direction of the spinning dope are parallel to each other, that is, when the angle between them is 0 degree, the spinning dope and coagulant fluid are not sufficiently mixed, and the obtained surface fibrils are obtained. The cross section of the modified fiber has a circular shape, an elliptical shape, and a rectangular shape, and the size of the cross section is also irregular, which is not preferable, but the fiber of the present invention can be obtained by mixing other polymers or selecting an appropriate solvent. . On the other hand, if it exceeds 90 degrees, the spinning dope and the coagulant fluid are sufficiently mixed, but the spinning dope discharge port, the coagulant jet port, etc. are likely to be clogged by the solidified polymer.

The spinning stock solution and the coagulant fluid need to be discharged and jetted so that they are sufficiently mixed, and as described above, it is necessary to adjust the angle between the discharge line direction of the spinning stock solution and the jetting line direction of the coagulant fluid. In addition, it is preferable to design the spinning stock solution discharge port and the coagulant fluid jet port as nozzles that allow both solutions to come into contact with each other.

In the present invention, it is preferable that the spinning stock solution is discharged and the coagulant fluid is jetted to the mixing cell portion provided at the confluence of the spinning stock solution discharge port and the coagulant fluid jet port. The spinning solution discharged into the mixing cell is mixed with the coagulant fluid in the mixing cell and coagulated by the coagulant.

The term "mixing cell" as used in the present invention means a point where coagulation and shearing of the polymer are caused by mixing the spinning dope and the coagulant fluid, and specifically, from the position where the spinning dope and the coagulant fluid are in contact with each other. It is a gap provided in the part and having a certain length.

The coagulation in the present invention means the substitution of the coagulant with the minimum solvent for forming the surface fibrillated fiber from the polymer solution, and the coagulated fiber has a gel state containing the solvent. It includes.

In the production method of the present invention, although not critical, the solidified polymer further solidifies in the mixing cell under a shearing flow rate, and fibrils having a diameter of 2 μm or less cover the fiber surface. Form an aggregate of fibers swollen with a coagulant or solvent.

The mixed fluid of the formed solidified body, solvent and coagulant fluid is discharged to the outside of the nozzle system, and the atmosphere to be discharged is a solidification adjusted by the solidifying agent or the mixed solvent of the solvent and the solidifying agent. The vapor phase or liquid phase of the liquid can be appropriately selected. The discharged coagulated body is often in a swollen state due to the solvent, and when directly laminated, the formed coagulated bodies are fused with each other, which may impair the quality of the obtained fiber. For this reason, it is preferable to discharge in a liquid phase, more preferably in a mixed solution of a polymer solvent and a coagulant, to complete coagulation of fibers in a swollen state, and to perform post-treatment such as washing efficiently. Above, the surface fibrillated fiber of the present invention can be predominantly produced.

When the formed coagulated body is directly injected into the coagulating liquid, the surface fibrillated fiber of the present invention can be obtained without the mixing cell.

In the present invention, it is preferable to use, in addition to the cellulose ester, a polymer other than the cellulose ester, which is soluble in a solvent for dissolving the cellulose ester, in combination with the cellulose ester. As a combination of the cellulose ester and the other polymer, it is necessary to select a combination having different coagulability with respect to the coagulant. The reason for this is not to say that, when the spinning dope discharged from the nozzle port is solidified in the mixing cell under shear of the coagulant fluid, fibrils are easily generated due to the difference in the coagulation rate of each polymer. It is supposed to be because.

As such a combination, an acetylation degree of 58 is obtained.
% Or less of cellulose diacetate and cellulose are preferable, and the solvent in that case is a tertiary amine oxide,
Nitrodiene dioxide (N ₂ O ₄ ) / dimethylformamide (DMF) mixed solvent, lithium chloride (LiCl)
A mixed solvent of / dimethylacetamide (DMAC) and the like can be used, and steam can be used as the coagulant. Using a polyacrylonitrile-based polymer as a polymer other than cellulose ester, it is also preferable to use a combination of cellulose acetate and polyacrylonitrile-based polymer, as the solvent in that case, for example, dimethylformamide, dimethylacetamide and the like to be used You can

In the present invention, the precursor fiber of the surface fibrillated fiber thus obtained can be beaten to be extremely fine. As the beating method, an apparatus such as a mixer or a beater which is generally used for a solution in which water is dispersed can be used to obtain a fiber aggregate in which the ratio of the precursor fiber and the fibril-containing split fiber is changed. It is also possible to add a thickener or an antifoaming agent depending on the post-process of shaping into a sheet. It is also possible to cut the precursor fiber to an appropriate length, prepare an aqueous dispersion, once form a sheet by a known method, and then beat with a water stream or an air stream.

[0036]

BEST MODE FOR CARRYING OUT THE INVENTION Here, the case where cellulose is used as a polymer other than cellulose ester as the polymer substance of the present invention will be described in detail below. As the cellulose ester, cellulose diacetate having an acetylation degree of 58% or less is preferable. The reason is that if the degree of acetylation is 58% or more, it will be difficult to dissolve in a solvent of cellulose described later. The cellulose material can be selected from dissolving pulp, pulp floc, and the like. These pulps may contain hemicellulose, lignin and the like. Among these, it is preferable to use pulp having an α-cellulose content of 90% by weight or more. The pulp used as the cellulosic material may be in the form of a sheet or a powder. The sheet-like material may be made into a chip-like shape with a cutting machine such as a shredder. Further, the pulp may be pulverized into particles as long as the molecular weight of cellulose is not significantly reduced. As a solvent of cellulose acetate and cellulose, N-methylmorpholine-N-oxide which is a tertiary amine oxide, and N-
A mixed solvent composed of a solvent which can be uniformly mixed with methylmorpholine-N-oxide and which is incapable of dissolving cellulose (hereinafter referred to as a non-solvent) can be mentioned. Here, water is preferably used as the non-solvent.

The spinning dope containing cellulose acetate and cellulose can be prepared either continuously or batchwise. That is, the dissolution may be continuously adjusted using a screw type extruder or the like, or the batch dissolution may be adjusted using a tank-type kneader equipped with a heating means and a reduced pressure deaeration means. The melting temperature is not particularly limited, but is 90 to 120 ° C.
It is preferable to carry out the treatment within a certain range. If the melting temperature is too high, the degree of polymerization may be lowered due to the decomposition of cellulose and the decomposition and coloring of the solvent may be remarkable, and if it is too low, the dissolution may be difficult.

The mixing ratio of cellulose acetate / cellulose for obtaining the fiber of the present invention is 100/0 to 30/70.
%, Preferably 95/5 to 60/40% by weight. The concentration of the solution is preferably in the range of 6 to 25% by weight. Further, it is preferably 10 to 22% by weight. The contents of N-methylmorpholine-N-oxide in the mixed solvent used for the spinning dope and the solvent that is a non-solvent for cellulose and that can be mixed with N-methylmorpholine-N-oxide are 48 to 40%, respectively. 90% by weight and 5 to 22% by weight are preferred. When water is used as the non-solvent for cellulose, in the step of introducing the polymer into the mixed solvent, the proportion of water is set to a large value of 20 to 50% by weight, and then water is removed under reduced pressure heating, Water ratio 5 to 2
It is preferably adjusted to 2% by weight.

Next, the case of using a polyacrylonitrile polymer as a polymer other than cellulose acetate will be described. The acrylonitrile-based polymer used in the present invention is not particularly limited as long as it is a polymer that constitutes ordinary acrylic fibers. The copolymerization component of acrylonitrile is not particularly limited as long as it is a copolymerization monomer that constitutes an ordinary acrylic fiber, and examples thereof include the following monomers. That is, acrylic acid esters represented by methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, 2-hydroxyethyl acrylate, hydroxypropyl acrylate, and methacrylic acid. Methyl, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-hexyl methacrylate, cyclohexyl acrylate, lauryl acrylate,
Methacrylic acid esters represented by 2-hydroxyethyl methacrylate, hydroxypropyl methacrylate, diethylaminoethylethyl methacrylate, etc., acrylic acid, methacrylic acid, maleic acid, itaconic acid, acrylamide, N-methylol acrylamide, diacetone acrylamide, It is an unsaturated monomer such as styrene, vinyltoluene, vinyl acetate, vinyl chloride, vinylidene chloride, vinylidene bromide, vinyl fluoride and vinylidene fluoride. Furthermore, for the purpose of improving dyeing, p-sulfonylmethallyl ether, methallylsulfonic acid, allylsulfonic acid, styrenesulfonic acid, 2-acrylamido-2-
You may copolymerize methyl propane sulfonic acid, these alkali metal salts, etc. The molecular weight of the acrylonitrile polymer used in the present invention is not particularly limited, but a molecular weight of 100,000 or more and 1,000,000 or less is desirable. Molecular weight 10
If it is less than 10,000, the spinnability tends to decrease, and at the same time, the quality of the raw yarn tends to deteriorate. If the molecular weight exceeds 1,000,000, the polymer concentration that gives the optimum viscosity of the spinning dope will be low, and the productivity will tend to be low.

Examples of the solvent used in the mixture of cellulose acetate and acrylonitrile-based polymer include:
Examples include dimethylformamide and dimethylacetamide. Preparation of the spinning solution can be easily performed by a generally known method.

When a polymer other than cellulose acetate is used, there is no problem in the state of the solution as long as the two polymers do not undergo phase separation, and there is no problem with other polymers. It is also possible to add a molecular polymer substance, metal fine particles, a modifier or a coagulant in advance.

The spinning dope thus obtained is supplied to the spinning nozzle 1 by a pump or an extruder for extruding a highly viscous solution which is usually used industrially. 3 and 4 show a spinning nozzle 1 used in the present invention. The spinning nozzle 1 of the present invention comprises a spinning stock solution discharge part 2, a coagulant fluid jet part 3, and a mixing cell part 4 in which the spinning stock solution and the coagulant fluid join together. Part 2
The mixing cell portion 4 is arranged in a straight line along the downstream direction of the.

The spinning dope discharge unit 2 has a supply chamber 2b connected to the spinning dope supply port 2a, and a spinning dope channel 2c for controlling the direction of the spinning dope discharge. The supply chamber 2b has a cylindrical shape extending in the vertical direction, and the lower end thereof is gradually narrowed and linearly connected to the spinning stock solution flow passage 2c having a capillary shape. The supply port 2a and the supply chamber 2b can be appropriately set according to the polymer and solvent used in the spinning dope, the viscosity of the spinning dope, or the discharge amount. The capillary-shaped spinning stock solution flow path 2c
Communicates with the upper wall surface of the mixing cell section 4 to form the spinning stock solution discharge port 2d. It is sufficient to set the spinning stock solution flow path 2c to a length that does not cause skew when the spinning stock solution is discharged from the spinning stock solution discharge port 2d and merges with the coagulant fluid. This can be easily achieved by the structure used for the shape of the spinning nozzle used in spinning.

As shown in FIG. 4, the spinning stock solution flow path 2c is projected from the upper wall of the mixing cell section 4 to form the spinning stock solution discharge port 2d in the middle of the mixing cell section 4. Is also possible. Further, in order to control the discharge direction of the spinning dope, it is possible to form a tapered throttle part at the downstream part of the spinning dope channel 2c and further to form a capillary downstream of the throttle part. Spinning stock solution flow path 2c
Can be appropriately selected depending on the spinning solution. The size of the spinning solution discharge port 2d depends on the viscosity of the polymer solution,
It can be appropriately selected according to the discharge amount, but is generally the diameter of the nozzle used for spinning with the polymer solution as the spinning stock solution,
It is appropriately set within the range of several tens μm (20 μm) to several mm (2 mm). The shape of the discharge port is not particularly limited, but a circular discharge port is preferably used.

The coagulant spraying section 3 has a supply chamber 3b in which a supply port 3a for the coagulant fluid is formed, and a coagulant channel 3c for controlling the discharge direction of the coagulant fluid. The agent flow path 3c communicates with the upper wall surface of the mixing cell section 4 to form a circular opening surrounding the spinning stock solution discharge port 2d, and the opening forms the coagulant fluid ejection port 3d. It is also possible to form the coagulant channel 3c in communication with the side wall surface of the mixing cell section 4.

The angle θ formed by the center line of the coagulant channel 3c with the center line of the spinning dope channel 2c is in the range of 0 ° ≦ θ <90 ° in the discharge direction of the spinning dope. It is formed. As shown in FIG. 3, the range may be 0 ° <θ <90 °. Alternatively, it may be 0 ° as shown in FIG. By setting the angle θ in this way, the coagulant fluid is adjusted to 0 ° or more, 90 °
It can be ejected at an angle of less than degrees. The angle θ is preferably 20 ° to 80 °, more preferably 3 °.
The coagulant channel 3c is set so as to be in the range of 0 ° to 70 °.
Set.

Further, in the coagulant flow path 3c, the spinning dope discharge port 2d is arranged on the upstream side of the intersection P between the center line of the coagulant flow path 3c and the center line of the spinning dope solution 2c. Is formed as. The distance L between the intersection P and the spinning solution discharge port 2d is preferably 0 mm ≦ L ≦ 10 mm. When the spinning dope discharge port 2d is located downstream of the intersection P, the spinning dope and the coagulant fluid are not sufficiently mixed, the degree of fibril formation is extremely reduced, and at the same time, the surface fibrillated fiber is mainly contained. The shape of the fiber is an ellipse or a film, which is not preferable. On the other hand, if it is above the intersection point P more than necessary, the spinning stock solution and the coagulant fluid are not smoothly mixed, and the mixing cell section 4
The polymer adheres to the wall surface of the above and induces blockage of the mixing cell portion 4. Further, it is preferable that the spinning solution discharge port 2d and the coagulant jet port 3d are as close as possible within the restriction range in manufacturing the nozzle in order to improve the degree of fibril generation.

Further, the coagulant channel 3c in the present embodiment has a circular slit shape surrounding the spinning stock solution discharge port 2d, which discharges the coagulant fluid from the spinning stock solution discharge port 2d. The shape is suitable for uniformly spraying the spinning dope onto the peripheral surface. It is also possible to dispose a plurality of capillary channels radially around the spinning solution discharge port 2d. When the coagulant channel 3c has a slit shape, the opening of the slit is not particularly limited, but can be set within a range of approximately 20 μm to 1 mm. It is preferable that the ejection amount of the coagulant fluid is set according to the ejection amount of the spinning dope so that a desired surface fibrillated fiber form is obtained. It is preferable that the coagulant fluid is injected in a gaseous state. At this time, it is easier to control the pressure than to control the ejection amount of the coagulant fluid by controlling the opening of the slit. It is also possible to provide the coagulant fluid jet in the center of the spinning dope discharge port.

The mixing cell portion 4 has the spinning stock solution discharge port 2d and the coagulant spray port 3d on the upper wall, and has a cylindrical shape in which the lower part is opened to form the discharge port 4a, and the diameter is 1 mmφ or more, It is set to 6 mmφ or less. The mixing cell portion 4 needs to have a length of at least 1 mm or more downstream from an intersection point P of the center line of the spinning dope solution channel 2c and the center line of the coagulant channel 3c. Can be appropriately set according to the discharge amount of the above, the spray amount of the coagulant fluid, or the desired form of the surface fibrillated fibers. The length of the mixing cell portion 4 is such that the spinning stock solution can secure a time required for solidifying into a fiber form and the length required for the polymer to form surface fibrillated fibers by shearing. Is sufficient, approximately 1 mm or more, preferably 10 mm or more downstream from the intersection point P,
More preferably, it is 30 mm or more. In addition, when the formed coagulated body is directly injected into the coagulation liquid, the surface fibrillated fiber of the present invention can be obtained without the mixing cell, but the spinning stock solution discharge port 2d and the coagulant fluid ejection port are provided. It is preferable to provide a mixing cell having a length that does not block 3d.

When the length of the mixing cell portion 4 is increased, the average denier of the main fibers obtained becomes smaller, and the diameter of the fibrils also becomes smaller. However, if the length is longer than necessary, clogging occurs due to the main fibers and fibrils formed. Easier to do. On the contrary, when the length of the mixing cell portion 4 is shortened, the average denier of the main fiber is increased, and the main fiber itself is less likely to branch, and the cross-sectional shape of the main fiber is elliptical to non-uniform in film shape. Becomes

The diameter of the mixing cell 4 is a factor that governs the linear flow velocity of the coagulant fluid in the mixing cell section 4, which is an important requirement for obtaining the surface fibrillated fibers targeted by the present invention. Yes, it is necessary to set the size so that a sufficient linear flow velocity can be obtained. The shape is not limited to the cylindrical shape as described above, and a rectangular slit may be used, and in that case, the width of the cross section is preferably 1 mm or more and 6 mm or less. If the cross-sectional area of the mixing cell portion 4 is reduced, the linear flow velocity increases, but clogging due to the formed main fibers and fibrils is likely to occur, which causes a problem.
Conversely, if the cross-sectional area of the mixing cell section 4 is increased, the linear flow velocity of the coagulant fluid decreases, and the degree of generation of fibrils decreases. The flow rate required to obtain the desired surface fibrillated fibers is, for example, 100 m / sec., When using the vapor phase as the coagulant fluid. More speed is required. Even if the cross-sectional area of the mixing cell section 4 is increased, it is possible to secure a necessary linear flow rate by increasing the flow rate of the gas phase. And the economic disadvantage is increased. The mixing cell portion 4 may have any shape as long as it has a sufficient length and a cross-sectional area capable of ensuring a required linear flow velocity as described above, and may have any shape such as a circular shape or a rectangular shape. The object of the invention can be achieved. Further, the mixing cell portion 4 may have a shape in which the cross-sectional area is gradually reduced or gradually increased toward the discharge port 4a, or the tip of the mixing cell portion 4 may be rounded to widen the discharge port 4a.

It should be noted that it is possible to provide a plurality of the spinning stock solution discharge ports 2d in the mixing cell section 4, and further to dispose the coagulant jet port 3d for each of the plurality of the spinning stock solution discharge ports 2d. Therefore, the spinning nozzle can be provided in one mixing cell section 4, and a spinning nozzle with high productivity can be obtained.

On the other hand, when the length of the mixing cell is kept constant and the discharge amount of the spinning dope is changed, the average denier of the main fibers obtained becomes thicker and the fibrils become larger when the discharge amount is increased, while the fiber length becomes longer. Become. Conversely, when the discharge rate is reduced, the average denier of the main fiber becomes smaller and the diameter of the fibril becomes smaller, while the fiber length becomes shorter.

The jetting amount of the coagulant fluid has a role of imparting shear in the mixing cell and at the same time coagulating the polymer by contact with the spinning dope. The appropriate amount of coagulating fluid for sufficient coagulation depends on the type of polymer, the degree of polymerization of the polymer, the polymer concentration of the polymer solution, the discharge amount of the polymer solution, the type of coagulant used, and the temperature. It is necessary to set appropriately. In the present invention, for example, when a gas phase coagulant fluid is used, the coagulant fluid of the coagulant fluid in the mixing cell can be secured so as to ensure a linear flow velocity necessary to give sufficient shear to the spinning dope. Set the flow rate. As shown in Examples of the present invention, when a coagulant fluid in a gas phase is used as a coagulant fluid, the weight ratio of polymer / coagulant is generally in the range of 10 to 200, but is not particularly limited. Absent. The coagulant fluid can be appropriately selected depending on the polymer to be used, but water is predominantly used industrially. Further, in obtaining a sufficient shear flow rate, it is more effective that the coagulant fluid is in the gas phase, that is, by utilizing steam as the coagulant fluid, it is possible to obtain the surface fibrillated fiber of the present invention. A sufficient shear rate can be easily obtained.

As mentioned above, the length of the mixing cell, the cross-sectional area,
By adjusting the discharge amount of the spinning dope, the polymer concentration of the spinning dope, and the jetting amount of the coagulant, it is possible to obtain the surface fibrillated fibers having different average denier and fiber diameter.

In this way, the spinning stock solution prepared by the above-described method is supplied from the spinning stock solution supply port 2a to the spinning stock solution discharge part 2, and the coagulant fluid is supplied from the coagulant supply port 3a. Supply to the injection unit 3. The spinning dope is supplied to the spinning dope supply chamber 2b of the spinning dope discharge unit 2.
The discharge direction is defined by the spinning stock solution flow path 2c through the spinning stock solution flow path 2c, and the spinning stock solution is discharged into the mixing cell section 4 from the spinning stock solution discharge port 2d. At the same time, the coagulant fluid passes through the supply chamber 3b of the coagulant injection unit 3 and the coagulant flow path 3
An injection angle is defined by c, and the injection is performed from the coagulant injection port 3d toward the spinning dope in the mixing cell section 4. The stock solution for spinning is mixed with the sprayed coagulant fluid, and is subjected to coagulation and shearing in the mixing cell section 4 to be shaped into surface fibrillated fibers.

Further, the coagulated body is discharged from the mixing cell 4 into the coagulating liquid, and the solvent is removed by a known method to obtain the surface fibrillated fiber of the present invention. Further, by beating the surface fibrillated fiber by a conventional method, the fibril-containing split fiber of the present invention containing the desired fibril fiber can be obtained. The fibril-containing split fiber according to the present invention can be formed into a non-woven fabric or a paper form by continuously attaching a known sheet shaping device after the washing step and the beating step, shaping the sheet, and then drying the sheet by a known method. . The solvent and the coagulant used in the present invention are recovered by a known method such as distillation.

[0058]

EXAMPLES The present invention will now be described by way of examples. Example 1 N-Methylmorpholine N-oxide (155 g of cellulose diacetate (MBH manufactured by Daicel Chemical Industries, Ltd.) and 75 g of cellulose (dissolving pulp V-60 manufactured by P & G Cellulose Co., Ltd.) containing about 41% by weight of water ( 2000 g (manufactured by San Techno Chemical Co., Ltd.) and 15 g of propyl gallate were put into a mixer (ACM-5 type) with a vacuum defoaming device manufactured by Kodaira Seisakusho, and 670 g of water was dehydrated while mixing under reduced pressure heating for about 2 hours to obtain cellulose. A uniform solution of acetate / cellulose was prepared. The kettle temperature was maintained at 100 ° C during the melting operation. The resulting solution is then added to 100
With the temperature kept at 0 ° C., it was extruded under a nitrogen pressure of 1.5 kg / cm ² , and a constant amount was supplied to the nozzle portion shown in FIG. 3 using a gear pump. The discharge rate of the spinning dope was defined by the rotation speed of the gear pump. Using steam as the coagulant fluid,
The amount of water vapor supplied was determined by defining the supply pressure with a pressure reducing valve. The amount of water vapor was measured by changing the supply pressure from the nozzle shown in FIG. 3 and injecting only water vapor into the water, and determining the increment in weight per unit time. The diameter of the spinning solution discharge port 2 is 0.2 mm, and the diameter of the mixing cell portion 5 is 2.
mm, length 24 mm, slit opening of coagulant fluid 3
90 μm, using a nozzle manufactured so that the angle between the discharge line of the spinning solution and the discharge line of water vapor is 60 degrees,
The supply amount of the spinning dope is 4.5 ml / min. The steam was supplied at a pressure of 1.0 kg / cm ^2, and the water was jetted into water at a temperature of 30 ° C. The water vapor consumption at this time is 73 g / m in terms of water.
and the linear velocity of water vapor in the mixing cell was calculated to be about 660 m / sec. , Steam / polymer ratio is about 10
It became 0. The fibers suspended in the coagulation liquid were collected, further washed in boiling water for 1 hour or more, and air-dried at room temperature.

The fiber thus obtained was observed with a scanning electron microscope to observe the cross section and side face of the fiber. The obtained fiber has a diameter of 1 μm to 100 μm and a length of 1 to 10 cm,
The surface fibrillated fiber had a structure in which fibrils of 0.1 to 1 μm were laminated on the fiber surface along the fiber axis direction. An electron micrograph of the fiber is shown in FIG. 5 (fiber side surface) and FIG. 6 (fiber cross section). The obtained surface fibrillated fiber was used as a precursor fiber and cut into 5 m / m to obtain 5 g of the fiber.
Was dispersed in 1 L of water and beaten for 30 seconds with a household mixer. After the beating treatment was air-dried, the morphology of the side surface of the fiber was observed using a scanning electron microscope. Diameter 1μ
It was observed that fibrils of m or less were split from the precursor fiber and entangled. The obtained electron micrograph is shown in FIG. Further, the beating process was continued, and the beating process was performed for 5 minutes. The fibers obtained in the same manner were air-dried, and then the side surface was observed with a scanning electron microscope. The fibers were aggregates of ultrafine fibers having a diameter of 1 μm or less, with almost no precursor fiber shape. FIG. 8 shows the obtained electron micrograph. Furthermore, when the beating process was continued and the beating process was performed for a total of 20 minutes and the fiber shape was observed, it was observed that the ultrafine fibers made of fibrils having a diameter of 1 μm or less were entangled.

[Example 2] 230 g of cellulose diacetate (MBH manufactured by Daicel Chemical Industries, Ltd.) and about 41% by weight
Water-containing N-methylmorpholine N-oxide 2
While mixing 000 g and 15 g of propyl gallate using the same apparatus as in Example 1, 700 g of water was dehydrated,
A solution of cellulose diacetate was prepared. Next, while keeping the obtained solution at 90 ° C., the solution was extruded under a nitrogen pressure of 1.5 kg / cm ² , and was introduced into a nozzle similar to that of Example 1 using a gear pump at 4.5 ml / min. It was supplied at a constant rate. Further, as in Example 1, water vapor was supplied as a coagulant fluid to the mixing cell while maintaining the pressure at 1.0 kg / cm ² with a pressure reducing valve. When the supply flow rate of water vapor was measured by the same method as in Example 1, it was 72 g / min. Met. Example 1
In the same manner as in (1), the mixture was discharged into a coagulating liquid composed of water, the floating cellulose diacetate fibers were collected, thoroughly washed and dried. The obtained fiber was a surface fibrillated fiber similar to the precursor fiber of Example 1, but the diameter was often 2 μm or less, and the length thereof was about 1 to 2 cm. When the obtained precursor fibers were beaten for 5 minutes in the same manner as in Example 1, as shown in FIG. 9, most of the precursor fibers were split by beating and formed into fibrils having a diameter of 2 μm or less. became.

[Example 3] Using a stock solution prepared in the same manner as in Example 1, the length of the mixing cell of the nozzle was 54 m / m.
A cellulose diacetate / cellulose polymer was shaped in the same manner as in Example 1 except that the above was used. The obtained fiber was a surface fibrillated fiber having a structure in which fibrils having a diameter of 0.5 μm or less were laminated on the fiber surface. When this fiber was used as a precursor fiber and a beating treatment was carried out for 5 minutes in the same manner as in Example 1, almost the same precursor fiber as in Example 1 was formed into a fibrillar aggregate. [Example 4] Using a stock solution prepared in the same manner as in Example 1 except that the length of the mixing cell of the nozzle was 14 m / m,
The cellulose acetate / cellulose polymer was shaped in the same manner as in Example 1. The obtained fiber is a surface fibrillated fiber having a structure in which fibrils are laminated on the surface of the fiber, and the fiber is used as a precursor fiber in Example 1
Beating for 5 min. After a short break,
Fibrill fibers were observed in which the precursor fibers were beaten.

[Examples 5 to 9] Using the same polymers and solvents as in Example 1, solutions having different composition ratios of cellulose diacetate / cellulose and polymer concentrations were prepared in the same manner as in Example 1, Spinning was carried out in the same manner as in Example 1, and the same treatment was carried out to obtain a precursor fiber of the surface fibrillated fiber. The polymer ratio and the polymer concentration of the spinning dope are shown in Table 1. The surface fibrillated fibers obtained in Examples 5 to 8 had a structure in which fibrils having a diameter of 1 μm or less were laminated on the fiber surface around the surface fibrillated fibers, as in Example 1. As a result of performing a beating treatment for 5 minutes in the same manner as in Example 1, the precursor fiber was divided into fibrils with a diameter of 1 μm or less as in Example 1, and the fibrils were entangled. On the fiber surface of the precursor fiber obtained in Example 9, a portion in which fibrils of 2 μm or less were laminated in the fiber axis direction and a portion in which they were laminated in a mesh were observed, and it was observed that the precursor fiber was also partially branched. Was done. When the fiber of Example 9 was subjected to a beating treatment for 5 minutes in the same manner as in Example 1, a situation in which fibrils separated from the precursor fiber were entangled was observed, but compared to Example 1, the precursor was not divided. There was a lot of body fiber left.

[0063]

[Table 1]

Comparative Example 1 117 g of cellulose (dissolving pulp V-60 manufactured by P & G Cellulose Co., Ltd.), 2000 g of N-methylmorpholine N-oxide containing about 41% by weight of water and 15 g of propyl gallate were used. Using a device similar to that described above, 648 g of water was dehydrated while mixing for about 2 hours to prepare a uniform solution of cellulose. In the melting operation, the pot temperature was kept at 100 ° C. Next, while keeping the obtained spinning solution at 100 ° C., it was extruded under a nitrogen pressure of 1.5 kg / cm ² and was quantitatively supplied to the nozzle portion shown in FIG. 3 using a gear pump. The discharge rate of the cellulose solution was defined by the rotation speed of the gear pump. As in Example 1, steam was used as the coagulant fluid. The diameter of the spinning solution discharge port 2 is 0.2 mm, the diameter of the mixing cell portion 5 is 2 mm, and the length is 54 mm.
mm, the slit opening of the coagulant fluid was 390 μm, and the nozzle was manufactured so that the angle between the discharge line of the spinning dope and the discharge line of the water vapor was 60 degrees, and the supply amount of the spinning dope was 6.0 ml / min. , Steam supply pressure 1.5kg
/ Cm ² and was jetted into water at a temperature of 30 ° C. When the water vapor consumption at this time was measured by the same method as in Example 1, it was 87 g / min in terms of water, and the linear flow velocity of water vapor in the mixing cell was calculated to be about 800 m / sec. became. It was discharged into a coagulating liquid composed of water in the same manner as in Example 1, the floating cellulose fibers were collected, thoroughly washed and dried. In the obtained cellulose fiber, a structure in which fibrils having a diameter of 0.1 μm to several μm were branched was observed, but the fiber surface had only irregularities, and a state in which the fibrils were laminated on the surface of the fiber was not observed. . The obtained fiber was beaten for 5 minutes in the same manner as in Example 1, but only some fibrils were branched.

Example 10 115 g of the cellulose diacetate used in Example 1 and acrylonitrile / vinyl acetate = 93/7% by weight were used as a medium for water and ammonium persulfate and sodium sulfite were used as a polymerization catalyst to carry out polymerization.
After washing and drying, the obtained specific viscosity was 0.17 (0.1 g / 1
115 g of an acrylonitrile-based polymer (measured at 25 ° C.) in a DMF solution of 00 cc) was dissolved in 770 g of dimethylacetamide to obtain a mixed solution of cellulose diacetate / acrylonitrile-based polymer of 23% by weight. Using this mixed solution as a spinning dope, using the same nozzle as in Example 1,
The spinning dope was kept at 50 ° C., and 9.0 ml / min. The mixture was discharged into the mixing cell at a speed of. Steam was used as a coagulating fluid, and the steam pressure was kept at 1.0 kg / cm ² and jetted into the mixing cell. The water vapor flow rate was measured in the same manner as in Example 1, and as a result, it was 75 g / min. Met. After the obtained fibers were washed and dried, the morphology of the fibers was observed. The obtained fiber has a thickness of 1 μm to 100 μm, and has a structure in which fibrils having a diameter of 2 μm or less are laminated in the fiber axis direction on the fiber surface. When the obtained fiber was beaten for 5 minutes in the same manner as in Example 1, a structure in which fibrils having a diameter of 2 μm or less were laminated was observed. The obtained electron micrograph is shown in FIG.

Example 11 Example 1 was repeated except that the same solution as in Example 10 was used and the length of the mixing cell section was 1.5 mm.
Spinning was performed under the same conditions as 0. The obtained fiber is used in Example 1.
When the fibers beaten for 5 minutes in the same manner as in (4) above were observed with a scanning electron microscope, it was found that fibers similar to those in Example 10 were formed.

[Example 12] The same solution as in Example 10 was used, and spinning was performed using a nozzle having a shape shown in Fig. 4 in which the ejection line of the solution and the ejection line of the coagulant were parallel to each other. The nozzle has a diameter of 2 mmφ for the outlet of the spinning dope, an opening of the coagulant fluid channel of 250 μm, an angle between the centerline of the spinning dope and the centerline of the coagulant fluid channel of 60 degrees, and a length of 0. 3 mm
A mixing cell of As in Example 10, the temperature of the spinning dope was maintained at 50 ° C., and 9.0 ml / min. The mixture was discharged into the mixing cell at a speed of. Steam was used as the coagulant fluid, and the steam was jetted into the mixing cell while maintaining the steam supply pressure at 1.0 kg / cm ² . The water vapor flow rate was measured in the same manner as in Example 1 and was found to be 58 g / min. Met. At this time,
The linear velocity of water vapor in the mixing cell was calculated to be about 53
It became 0 m / sec. The fibers were spun into water at a temperature of 30 ° C., the obtained fibers were washed and dried, and the morphology of the fibers was observed. The obtained fiber had a thickness of 1 μm to 100 μm, and was a surface fibrillated fiber in which fibrils having a diameter of 2 μm or less were laminated on the surface of the fiber. When the obtained surface fibrillated fiber was used as a precursor fiber and a beating treatment was performed for 5 minutes in the same manner as in Example 1, a structure in which fibrils having a diameter of 2 μm or less were laminated was observed, but the precursor was not partially divided. Body fibers were also observed.

[Example 13] The same spinning dope and nozzle as in Example 11 were used, and the spinning dope discharge amount was 18.0 ml.
/ Min. The spinning was performed under the same conditions as in Example 12, except that When the obtained fiber was observed, Example 12
A fiber similar to was obtained.

Comparative Example 2 23 g of the cellulose diacetate used in Example 1 and 207 g of the acrylonitrile-based polymer used in Example 10 were dissolved in 770 g of dimethylacetamide, and cellulose diacetate / acrylonitrile-based polymer = 10 / A 90 wt% 23 wt% mixed solution was obtained. This polymer solution was spun under the same conditions using the same nozzles as in Example 10, and beaten for 5 minutes in the same manner as in Example 1 to observe the morphology of the obtained fiber. The fiber cross section was non-uniform such as circular or rectangular, the fiber surface had irregularities, and no fibrils that were split or branched were observed.

[Comparative Example 3] A polymer solution prepared in the same manner as in Example 2 was used as a spinning dope, and the solution was maintained at 90 ° C to give 4.5 ml / min. Two-fluid nozzle (SP
RAYING SYSTEMS CO.'S setup No. 22B) was blown into water at 30 ° C. together with steam of 2.0 kg / cm ² gauge pressure, but after a few minutes the nozzle was clogged and stable spinning was not possible.

[Comparative Example 4] A polymer solution prepared in the same manner as in Example 2 was used as a spinning dope, and spinning was carried out using the same nozzle as in Example 2. While keeping the spinning dope at 90 ° C, 4.5 ml / min. At the same time, it is discharged into the mixing cell at the same time, and the gauge pressure is 2.0 kg / c instead of steam.
m ² pressurized air was jetted from the coagulant fluid channel into the mixing cell. The bulk polymer was intermittently discharged from the mixing cell, and the fiber of the present invention was not obtained.

[0072]

The surface fibrillated fiber of the present invention is suitable for use in air filters and the like, especially in the field of base fiber for sheet-like materials such as non-woven fabrics which require high filtration performance with low pressure loss, or the texture of natural materials. Such as base fibers for artificial leather
It can be used effectively in a wide range of fields. Further, according to the production method of the present invention, it is possible to produce a fiber containing fibrils having a diameter of 2 μm or less by an industrially superior method, and further, it is possible to obtain a comparatively glass transition which is impossible by the conventional technique. It is possible to stably produce fibrils and ultrafine fibers of a polymer having a high temperature or a polymer that undergoes thermal modification at low cost, and its industrial significance is great.

[Brief description of drawings]

FIG. 1 is a schematic view showing a side surface of a surface fibrillated fiber of the present invention.

FIG. 2 is a schematic view showing a cross section of a surface fibrillated fiber of the present invention in a direction perpendicular to a fiber axis.

FIG. 3 is a sectional view showing an example of a nozzle used in the present invention.

FIG. 4 is a cross-sectional view showing another example of a nozzle used in the present invention.

FIG. 5 is an electron micrograph (2,000 showing an example of the morphology of the surface fibrillated fiber obtained in Example 1 of the present invention.
Times).

FIG. 6 is an electron micrograph (× 500) showing an example of the morphology of the surface fibrillated fibers obtained in Example 1 of the present invention.

FIG. 7: Precursor fiber obtained in Example 1 of the present invention
It is an electron micrograph (1,000 times) which shows an example of the fibril containing split fiber after beating for a second.

FIG. 8 is an electron micrograph (× 1,000) showing an example of fibril-containing split fibers after beating the precursor fiber obtained in Example 1 of the present invention for 5 minutes.

FIG. 9 is an electron micrograph (3,500 times) showing an example of the morphology of fibril-containing split fibers obtained by beating the precursor fiber obtained in Example 2 of the present invention for 5 minutes.

FIG. 10 is an electron micrograph (× 1,000) showing an example of the morphology of fibril-containing split fibers obtained by beating the precursor fiber obtained in Example 10 of the present invention for 5 minutes.

[Explanation of symbols]

 A: main fiber B: fibril B ': fibril branched from main fiber surface B ": fibril completely separated from main fiber surface B'1: spinning nozzle 2: spinning stock solution discharge part 2a: spinning stock solution supply port 2b: spinning Stock solution supply chamber 2c: Spinning stock solution flow path 2d: Spinning stock solution discharge part 3: Coagulant injection part 3a: Coagulant supply port 3b: Coagulant supply chamber 3c: Coagulant flow path 3d: Coagulant injection port 4: Mixing cell part 4a: outlet P: intersection of the center line of the spinning channel and the center line of the coagulant channel θ: angle between the center line of the spinning channel and the center line of the coagulant channel

Front page continued (72) Inventor Takashi Kozakura 20-1 Miyukicho, Otake City, Hiroshima Prefecture Mitsubishi Rayon Co., Ltd.

Claims (11)

[Claims] 1. A fibril composed of a polymer containing at least 30% by weight of cellulose ester, wherein fibrils having a diameter of 2 μm or less cover most of the main fiber surface along the fiber axis direction of the main fiber. Surface fibrillated fiber. 2. The surface fibrillated fiber according to claim 1, which contains a polymer other than a cellulose ester that is soluble in a solvent that dissolves the cellulose ester. 3. A fibril having a diameter of 2 μm or less and a fibril having a diameter of 100 μm or less and having various thicknesses infinitely variable, which is composed of a polymer containing at least 30% by weight of a cellulose ester polymer, and has an aspect ratio (l / d). ) Is 1000
A fibril-containing split fiber comprising the above split fibers. 4. The fibril-containing split fiber according to claim 3, wherein the split fiber has a diameter of 2 μm or less, and the split fiber itself has a fibril shape. 5. The fibril-containing split fiber according to claim 3, which contains a polymer other than a cellulose ester which is soluble in a solvent for dissolving the cellulose ester. 6. When a spinning dope prepared by dissolving a polymer containing at least 30% by weight of a cellulose ester in a solvent is discharged from a spinning dope discharge port, a coagulant fluid of the polymer is discharged from a coagulant fluid jet port. Surface fibrillation, characterized in that it is jetted at an angle of 0 ° or more and less than 90 ° with respect to the discharge line direction of the spinning dope to coagulate the polymer in a shear flow rate and wash the formed coagulum. Fiber manufacturing method. 7. The surface fibrillated fiber according to claim 6, wherein the spinning stock solution is discharged and the coagulant fluid is jetted to a mixing cell portion provided at a confluence of the spinning stock solution discharge port and the coagulant fluid jet port. Production method. 8. The method for producing a surface fibrillated fiber according to claim 6, wherein the coagulated body coagulated at a shear flow rate is jetted into a coagulant solution. 9. The method for producing a surface fibrillated fiber according to claim 6, 7 or 8, wherein the solvent is a tertiary amine oxide. 10. The coagulant fluid is steam,
A method for producing the surface fibrillated fiber according to claim 7, claim 8 or claim 9. 11. A method for producing fibril-containing split fibers, characterized in that the surface fibrillated fibers obtained by the method according to claim 6 are made fine by beating.