JPH0655965B2 - Method for manufacturing ultrafine fiber bundle - Google Patents

Description

Detailed Description of the Invention

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an ultrafine fiber bundle, and more particularly to a method for producing an ultrafine fiber bundle in which an ultrafine fiber bundle can be obtained already when it is spun from a spinneret (die). [Prior Art] In the patent application dated September 25, 1984, Japanese Patent Application No. 59-198669, the applicant of the present application has proposed a thermoplastic resin having a substantially circular cross-sectional shape and a substantially indefinite length of 200 μm or less. An ultrafine fiber bundle in which a large number of resin ultrafine fibers are bundled in a substantially parallel state, and the ultrafine fibers composing the fiber bundle are bonded to each other. And its manufacturing method were proposed. The manufacturing method of the ultrafine fiber bundle at the time of this application is such that when a screw type extruder is melted and kneaded by adding a thermoplastic resin, water and an auxiliary agent for assisting the dispersion of water in the thermoplastic resin, Paying attention to the fact that fiber bundles are naturally formed in the extruder during melting and kneading, and after melting and kneading by a screw type extruder, a diameter of 200μ is obtained from one orifice hole.
The present invention is characterized by spinning a fiber bundle in which a large number of the following ultrafine fibers are bundled in a substantially parallel state. The method for producing such an ultrafine fiber bundle is already formed into an ultrafine fiber bundle in the extruder as compared with the conventional production method in which a molten polymer is extruded from an extruder and then stretched and spun. It is an epoch-making thing that can not be imagined from the spinning method so far. [Problems to be Solved by the Invention] Here, in order to make uniform and finer fibers, it is premised that water is finely dispersed in the thermoplastic resin. Dispersion of water is basically performed by a mixing and stirring action by a screw of an extruder, but as a premise of that, how much water should be injected has a great influence on the dispersion.
It became clear by the subsequent tests and studies. The present invention has been made under such a background, and in the production of the ultrafine fiber bundle, enables to effectively disperse water in the thermoplastic resin, and by extension, an ultrafine fiber bundle of uniform and finer fibers. It is a technical subject to be able to manufacture. [Means for Solving the Problems] In order to solve the above-mentioned technical problems, the present invention assists the dispersion of water in the thermoplastic resin, water, and the thermoplastic resin in the screw extruder 1. In the method for producing an ultrafine fiber bundle in which an auxiliary agent to be melted and kneaded is formed in the extruder during the melting and kneading and extruded from the die, the water injection port
11 are provided at a plurality of points of the screw type extruder 1, and water is injected from each inlet 11 to disperse the water in the thermoplastic resin at a plurality of points. [Operation] Hereinafter, the thermoplastic resin, the auxiliary agent, the water, the manufacturing apparatus and the like according to the present invention will be described, and then the specific manufacturing process will be described. <Thermoplastic Resin> The thermoplastic resin used in the production of the ultrafine fiber bundle according to the present invention may be any resin regardless of crystallinity or amorphousness as long as it is a resin that is water-insoluble and can be formed into fibers, for example, a high-pressure method Density polyethylene, medium and low pressure low density polyethylene, high density polyethylene, ultra high molecular weight polyethylene, polypropylene, ultra high molecular weight polypropylene, poly 1-butene, poly 3-methyl-1-butene, poly 4-methyl-1-pentene or ethylene , Propylene, 1-butene, 3-methyl-1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-decene and other α-olefin random or block copolymers, ethylene. Copolymerization of α-olefins such as butadiene copolymer and ethylene-ethylidene norbornene copolymer with conjugated or non-conjugated diene Coalesced, ethylene-propylene-butadiene terpolymer, ethylene-propylene-dicyclopentadiene 3
Copolymers of two or more kinds of α-olefins such as terpolymers, ethylene / propylene / ethylidene norbornene terpolymers and the like, conjugated or non-conjugated dienes, ethylene / acrylic acid copolymers, ethylene / vinyl acetate copolymers Polymers, ethylene / vinyl alcohol copolymers, ethylene / vinyl compound copolymers such as ethylene / vinyl chloride copolymers, polystyrene, acrylonitrile / butadiene / styrene copolymers, methyl methacrylate / styrene copolymers, α -Styrene resins such as methylstyrene / styrene copolymer, polyvinyl chloride, polyvinylidene chloride, vinyl chloride / vinylidene chloride copolymer, vinyl copolymers such as polymethyl acrylate and polymethyl methacrylate, nylon 6, nylon 6, Nylon 66, Nylon 610, Nylon 11, Nylon 1
Examples thereof include polyamides such as 2 and the like, thermoplastic polyesters such as polyethylene terephthalate and polybutylene terephthalate, polycarbonate, polyphenylene oxide, polysulfone, polyphenylene sulfide, polyether ether ketone and the like, or a mixture thereof.
Among these, low density polyethylene and ultra high molecular weight polyethylene, which have been particularly difficult to be made into ultrafine fibers, can be used in the same manner as other resins. <Auxiliary Agent> The auxiliary agent used in the production of the ultrafine fiber bundle according to the present invention is that when the thermoplastic resin and water are kneaded, water gradually disperses into the thermoplastic resin to cause phase inversion. The main function is to produce an aqueous dispersion in which the continuous phase is water, as a result of which the thermoplastic resin is dispersed in water. It is considered that the production of such a phenomenon by the melt-blending kneading is a cause of manufacturing the ultrafine fiber bundles in a lump. That is, without using an auxiliary agent, it is possible to use only the thermoplastic resin and water.
An ultrafine fiber bundle cannot be produced only by melt-kneading a person, and therefore the object of the present invention cannot be achieved. The general concept of an auxiliary agent having such an action is to have both a hydrophilic group and a lipophilic group in the molecule, and more specifically, the following compounds may be used alone or in combination of two or more kinds. To use. (A) Water-swellable or water-soluble thermoplastic resin (B) Water-insoluble or water-insoluble thermoplastic resin modified with unsaturated carboxylic acids (C) Surfactant (used in combination with A and / or B ) (D) Organic solvent (used together with A and / or B) (E) Other (used together with A and / or B) (A) Water-swellable or water-soluble thermoplastic resin For water It swells or dissolves (infinite swell), and examples thereof include polyvinyl alcohol, methyl cellulose, carboxymethyl cellulose or a sodium salt thereof, polyacrylic acid, sodium polyacrylate, polyacrylic acid amide, and the like. Among these, polyvinyl alcohol, especially saponification degree 65-
98 and even 80 to 97 partially saponified polyvinyl alcohols are preferred. These auxiliaries are kneaded together with the above-mentioned thermoplastic resin and water. First, the auxiliaries are uniformly kneaded into the thermoplastic resin, and then the swelling of the auxiliaries with water causes the thermoplastic resin to be divided. Further, water permeates into the inside and swells the auxiliary agent existing inside to promote the fragmentation of the thermoplastic resin, and finally gives an aqueous dispersion as if the thermoplastic resin was finely fragmented by water. Conceivable. The characteristics of this type of auxiliaries are that the number of types of thermoplastic resins that can be applied is less than that of the auxiliaries described below, and if the manufactured ultrafine fiber bundles are left to stand Is a fiber bundle that is strongly bonded, and a fiber bundle having hydrophilicity. (B) Poorly water-soluble or water-insoluble thermoplastic resin modified with unsaturated carboxylic acids Graft-copolymerized or block-copolymerized unsaturated carboxylic acids with a water-insoluble or water-insoluble resin, or a random copolymer in the resin It is a polymerized product, and in particular, one having good compatibility with the thermoplastic resin of the fiber raw material, and one having a small melting viscosity is preferable. The resin that is the standard of compatibility is the solubility parameter (Sp
Value), and the difference in Sp value is within 2 (Cal / cm ³ ) ^1/2 ,
Particularly, it is preferably within 1 (Cal / cm ³ ) ^1/2 . The Sp value is a value defined as the half power of the cohesive energy density, and the contribution value Vi of the atomic group to the molar volume and the cohesive energy En of the atomic group can be calculated as follows. W. Van. Klevelen “P
roperties of Polymers ”(Elsevier, 1972) It can be calculated from Further, the wax having a small melt viscosity can be exemplified by a wax having a small molecular weight. This modified resin is hydrophilic because it has a carboxy group or derivative group derived from unsaturated carboxylic acids, but it does not swell in water because the base resin is poorly water-soluble or water-insoluble. The unsaturated carboxylic acid unit in the modified resin may be an unsaturated carboxylic acid or its ester, or those which are neutralized or saponified to form an unsaturated carboxylic acid salt. Of unsaturated carboxylic acid salt in 1 g of polymer Those containing 0.1 to 5 millimole equivalents, particularly 0.2 to 4 millimole equivalents in terms of groups are preferable. The modified resin is a copolymer of a monomer that constitutes the poorly water-soluble or water-insoluble thermoplastic resin and an unsaturated carboxylic acid, and as the unsaturated carboxylic acid, (meth) acrylic acid, maleic acid, fumar Acid, tetrahydrophthalic acid, itaconic acid, citraconic acid, crotonic acid, isocrotonic acid, medic acid (endocis-bicyclo [2,
2,1] hept-5-ene-2,3-dicarboxylic acid),
Unsaturated carboxylic acids such as maleic anhydride and citraconic anhydride or anhydrides thereof, monoesters of the above unsaturated carboxylic acids such as methyl, ethyl, propyl and the like, esterified products such as diesters, alkali metal salts and alkaline earth metal salts. ,
Examples thereof include unsaturated carboxylic acid salts such as ammonia salts. Of course, it will be apparent to those skilled in the art that instead of copolymerizing a plurality of monomer components, a thermoplastic resin such as an olefin resin may be graft-polymerized or block-polymerized with the unsaturated carboxylic acid. As described above, the preferred embodiment of this modified resin is that the unsaturated carboxylate is contained in 1 g of the polymer. It is contained in an amount of 0.1 to 5 millimol equivalent in terms of group,
In order to produce the modified resin of this embodiment, a thermoplastic resin previously modified with an unsaturated carboxylic acid or anhydride or its ester is treated with a basic substance, that is, an alkali metal, an alkaline earth metal, ammonia and an amine as a base in water. Substances that act as, alkali metal oxides, hydroxides, weak acid salts, hydrides, alkaline earth metal oxides, hydroxides,
Examples thereof include a method of neutralizing or saponifying with a weak acid salt, a hydride, an alkoxide of these metals and the like. Specific examples of such basic substances are shown below. Examples of the alkali metal include sodium and potassium, examples of the alkaline earth metal include calcium, strontium, barium, amines such as hydroxylamine and inorganic amines such as hydrazine, methylamine, ethylamine, ethanolamine, cyclohexylamine, and alkali metals. Examples of the oxides, hydroxides, and hydrides of alkaline earth metals include sodium oxide,
Sodium peroxide, potassium oxide, potassium peroxide, calcium oxide, strontium oxide, barium oxide, sodium hydroxide, potassium hydroxide, calcium hydroxide,
Weak acid salts of strontium hydroxide, barium hydroxide, sodium hydride, potassium hydride, calcium hydride, alkali metals and earth metals include sodium carbonate, potassium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, hydrogen carbonate hydrate. Examples of the compounds of calcium, sodium acetate, potassium acetate, calcium acetate, ammonia and amines include ammonium hydroxide, quaternary ammonium compounds such as tetramethylammonium hydroxide and hydrazine hydrate. As the carboxylic acid group or carboxylic acid ester group neutralized or saponified with a basic substance, sodium carboxylates, alkali metal carboxylates such as potassium carboxylates, ammonium carboxylates are preferable, and potassium carboxylates are particularly preferable. preferable. (C) Surfactant The surfactant is not used alone as an auxiliary agent, but is used in combination with the above A and / or B. The surfactant used may be any of anionic surfactant, cationized, nonionic surfactant, and zwitterionic surfactant,
In particular, the nonionic surfactant which is an anionic surfactant, together with A and / or B, has a diameter of 100 μ or less and generally 50 μ or less.
It is preferable because less than ultrafine fibers can be produced. Here, as the anionic surfactant, in addition to those which have been in the form of anionic surfactant from the beginning, there are also organic compounds which react with the basic substances mentioned above to finally become anionic surfactant. Include. That is, it is better to melt-knead the thermoplastic resin with A and / or B and the organic compound, and then add the basic substance and continue the melt-kneading to convert the organic compound into the anionic surfactant. The resin and the anionic surfactant are well mixed, and ultrafine fibers having a smaller diameter can be obtained. Any organic compound may be used as long as it reacts with a basic substance to become an anionic surfactant, and preferred examples thereof include primary higher fatty acids, secondary higher fatty acids, primary higher alcohol sulfates, Secondary higher alcohol sulfate, primary higher alkyl sulfonic acid, secondary
Higher alkyl sulfonic acid, higher alkyl disulfonic acid, sulfonated higher fatty acid, higher fatty acid sulfate ester,
Higher fatty acid ester sulfonic acid, higher alcohol ether sulfuric acid ester, higher alcohol ether sulfonic acid,
Examples include alkylolated sulfuric acid ester of higher fatty acid amide, alkylbenzene sulfonic acid, alkylphenol sulfonic acid, alkylnaphthalene sulfonic acid, alkylbenzimidazole sulfonic acid and the like. Among these, higher fatty acids are particularly preferable, and saturated or unsaturated higher fatty acids having 10 to 20 carbon atoms are particularly preferable, and more specifically, capric acid, undecanoic acid, lauric acid, myristic acid, and palmitin. Acid, margaric acid, stearic acid, saturated fatty acids such as arachidic acid, linderic acid,
Examples thereof include unsaturated fatty acids such as tzunic acid, petroselinic acid, oleic acid, linoleic acid, linolenic acid, and arachidonic acid, and mixtures thereof, with saturated fatty acids being particularly preferred. Specific examples of the surfactant include anionic surfactants and nonionic surfactants, and the former include primary higher fatty acid salts, secondary higher fatty acid salts, primary higher alcohol sulfate ester salts, Sulfate of secondary higher alcohol sulfate ester, primary higher alkyl sulfonate, secondary higher alkyl sulfonate, higher alkyl disulfonate, sulfonated higher fatty acid salt, higher fatty acid ester sulfonate, higher alcohol ether Ester salt,
Sulfonates of higher alcohol ethers, alkylated sulfates of higher fatty acid amides, alkylbenzene sulfonates, alkylphenol sulfonates, alkylnaphthalene sulfonates, alkylbenzimidazole sulfonates, the latter of which are alkyl ethers and alkyl allyls. Ether, alkyl thioether, alkyl ester, sorbitan monoalkyl ester, polyoxyethylene alkylamine, polyoxyethylene alkyl amide, polyoxyethylene polyoxypropylene, pentaerythritol ester, saccharose ester, fatty acid ethanolamide, methylolamide, oxymethyl Examples thereof include ethanolamide. Of course, anionic and nonionic surfactants other than these examples, cationic surfactants and zwitterionic surfactants not exemplified here may be used, and more specific examples of these surfactants include, for example, Horiguchi. It is disclosed in Hiroshi "Synthetic Surfactants" (Sho 41, Sankyo Publishing). When one of the above-mentioned surfactants converted into an anionic surfactant by the addition treatment of a basic substance is used, the produced ultrafine fiber bundle exhibits the property on the alkaline side, that is, PH9 or higher. With nonionic surfactants, PH becomes ultrafine fiber bundles that show almost neutral properties. Incidentally, in the case of a nonionic surfactant, those having an HLB value of 13 to 19 are preferable because they become ultrafine fibers having a smaller diameter. The HLB value is derived from the Griffin's formula, and details are disclosed in the Handbook of Surfactants (Nishiichiro et al., Sangyo Tosho, Sho 35), pages 307-310. (D) Organic Solvent The organic solvent is used when a thermoplastic resin which has a high molecular weight or a narrow molecular weight distribution and a high melting gap viscosity and is difficult to melt knead is formed into an ultrafine fiber bundle. Therefore, melt flow rate (MF
When R, ASTM D 1238) is applied to a resin of less than 1 g / 10 min, the effect is remarkably exhibited, but of course, it can be applied to a resin having a small melting viscosity, that is, MFR of 1 g / 10 min or more. Further, the organic solvent is not used alone, but is used in combination with the above-mentioned A and / or B and optionally C. Examples of such organic solvents include aromatic hydrocarbons such as benzene, toluene, xylene, styrene, α-methylstyrene and vinylbenzene, aliphatic hydrocarbons such as hexane and heptane, and halogenated hydrocarbons such as trichloroethylene. is there. (E) Others In addition to those listed above in A to D, petroleum resin, rosin, asphalt and the like may be used in combination with A and / or B, if necessary, with C and D. Among them, water swelling of A or It is preferably combined with a water-soluble resin. <Preferred Embodiment of Auxiliary Agent> There are various usage forms of the auxiliary agent, for example, A or B is used alone, A and B are used in combination, A and / or B and C are used in combination, and A and / or B and D are used in combination. , A and / or B and C and D in combination, and A and E in combination. More preferably, a modified or neutralized or saponified modified resin (B) is used when the fiber diameter is relatively large (approximately 50 or more), and a neutralized or saponified modified resin (B) is used when the fiber diameter is thin (approximately 50 μm or less). When using a surfactant (C), especially when aiming for a neutral ultrafine fiber, select a nonionic surfactant as (C) among the above combinations, or use a resin ultrafine fiber with a high melting viscosity. When aiming, use a neutralized or saponified modified resin (B) and a surfactant (C) and an organic solvent (D), or further when strongly solidifying the fiber bundle itself, use a water-soluble resin (A). The amount of the auxiliaries used varies depending on the type of the thermoplastic resin to be made into the ultrafine fiber bundle or the type of the auxiliaries, but is generally 75 to 98 parts by weight of the thermoplastic resin, particularly 80 to 95 parts by weight and Auxiliary agent 2 to 25 parts by weight, especially 5 to 20 parts by weight (however, the total of both In particular, when a thermoplastic resin and a modified or neutralized or saponified modified resin and a surfactant are used as a preferred embodiment of the present invention, each is 75 to 98 parts by weight, 1 to 20 parts by weight, and 1 to 20 parts by weight. 5 parts by weight (total 100 parts by weight, especially 8
Mix at a ratio of 0 to 95 parts by weight, 3 to 16 parts by weight, and 2 to 4 parts by weight. In this combination, when the water-swelling or water-soluble thermoplastic resin is used instead of the surfactant, the ratio may be approximately the above. <Addition of water> The amount of water added to the system composed of the thermoplastic resin and the auxiliary agent is 3 to 4 with respect to 100 parts by weight of the total amount of the thermoplastic resin and the auxiliary agent.
0 parts by weight, especially 10 to 30 parts by weight. When the amount of water is within this range, the target thermoplastic resin can be made into an ultrafine fiber bundle. Further, the water to be added is not limited to pure water, but when a surfactant is used as an auxiliary, for example, there is a method of adding it as an aqueous solution and adding the surfactant and water together. <Device used in the present invention>

[Extruder]

The extruder used in the present invention is described below in <Production of ultrafine fiber bundle>
For the reason described in Section 1, as shown in FIG. 1, it is desirable that the single-screw extruder 1 is such that shearing force does not act in a direction parallel to the extrusion direction of the molten resin. As the screw shape, an intermediate mixing type screw is preferably used. Further, in the middle of the cylinder 10 (also referred to as a barrel) of the extruder 1, there are provided injection ports 11 for injecting water into the thermoplastic resin at a plurality of positions, and the pumps 4 are connected to the injection ports 11, respectively. . As the pump 4, for example, a high pressure plunger pump is used. The location where the water inlet 11 is provided is determined in consideration of the basic function of the extruder and the phase change process of the thermoplastic resin based on this basic function. The process of this phase change in the extruder shown in FIG. 1 will be described. The thermoplastic resin and the auxiliaries supplied from the hopper 12 are first conveyed and compressed in a solid state and gradually melted and kneaded. In this process, it is important that the thermoplastic resin and the auxiliary agent are completely melted. If water is injected in the next step while the thermoplastic resin is not sufficiently melted, water will flow through the gap of the unmelted resin and flow back to the hopper 12 side, resulting in poor extrusion or impossible extrusion. . Water is pressed in when the thermoplastic resin is completely melted and has a sealing function. The water injected under pressure is dispersed in the molten resin due to the kneading effect of the screw, but in order to carry out this dispersion more effectively, a plurality of water inlets 11 are provided. Further, in order to carry out the dispersion effectively, it is preferable to provide a known intermediate mixing portion such as a dullage portion. When the water thus finely dispersed in the resin is subsequently kneaded by the screw, the water will be in the state of phase inversion, which will be described later in <Production of ultrafine fiber bundle>, to form a fiber bundle. From the above, it can be said that the water inlet 11 is preferably provided immediately after the place where the thermoplastic resin is completely melted. Also,
When the intermediate mixing section is provided, it is preferable to provide the injection port 11 on the upstream side thereof. A plurality of inlets 11 may be provided in the axial direction of the cylinder 10 as shown in FIG. 1, and a plurality of inlets 11 may be provided in the circumferential direction of the cylinder 10 as shown in FIG.

[Die]

As the die 2 of the extruder 1, in addition to a normal spinneret having a single or a plurality of orifices 3, a die having a porous member such as a mesh screen as an orifice can be used. Furthermore, it is also possible to use a T-die or a circular die. It is also possible to use a die as shown in FIG. The diameter of the orifice 3 when using a die as shown in Fig. 3 is 0.1-3mm.
φ, preferably 0.3 to 1.5 mmφ.

[Disentanglement device]

As a device for defibrating the fiber bundle extruded from the orifice 3 of the die 2, nozzle openings 6 are provided above and below the orifice 3 as shown in FIGS. It is possible to spray gas from the mouth 6 toward the ultrafine fiber bundle from above and below by compressed air by the air compressor 7, or mechanical means such as a so-called crusher, or liquid such as water jet. It can also be carried out by the means used. Further, after cutting the spun fiber bundle into a predetermined size, it can be passed through a disintegrator or a disintegrator such as a pulper to obtain monofilament cotton or disintegrated slurry of monofilaments. . <Production of Ultrafine Fiber Bundle> To produce an ultrafine fiber bundle using the above apparatus, the above-mentioned thermoplastic resin, auxiliary agent and water are melt-kneaded and spun from the orifice 3 of the spinning nozzle as the die 2. . This makes it possible to spin one fiber bundle in which a large number of ultrafine fibers having a diameter of 200 μ or less per one orifice 3 are bundled in a substantially parallel state. At this time, it is important to extrude under the condition that water is not substantially flushed, and it is necessary to pay attention to the fact that if there are a plurality of orifices 3, a fiber bundle is formed for each orifice 3. Furthermore, in order to convert the resin composition to be melt-kneaded into a form in which single fibers are bundled in parallel, in order to prevent shearing force in a direction parallel to the pressing direction of the molten resin in the extruder, that is, It is generally necessary to carry out the kneading so that the shearing force is applied only in the two-dimensional directions except for the parallel method. Explaining this point, so-called O / W in which water becomes a continuous phase and molten resin becomes dispersed particles under a melt-kneading condition in which a shearing force acts in a three-dimensional direction like melt-kneading in a twin-screw extruder.
Mold phase inversion easily occurs, and a continuous fibrous resin cannot be obtained. This is the reason why the single-screw extruder suitable for shearing / kneading in only the two-dimensional direction is preferable as the extruder to be used in the method of the present invention. However, it goes without saying that even a multi-screw extruder can be used as long as it is improved to suit the present invention. In the dispersed state of the melt formed by the method of the present invention, the molten resin is a large number of independent columnar phases oriented in the extrusion direction and water is present in the form of a packed phase filling the interstices of these large number of columnar phases. . That is, in this dispersion form, the cross-section with respect to the extrusion direction is a so-called O / W dispersion form in which the molten resin is a dispersed phase and the water is a continuous phase, but both the molten resin and water are substantially in the extrusion direction. It is considered to be continuous.
Then, the water added to the system is gradually taken into the molten resin by the shearing force due to the kneading and the action of the auxiliary agent, and becomes a W / O type dispersion at first. Furthermore, when the shearing force in the two-dimensional direction is continuously applied, the amount of dispersed water is small (3 to 40 parts by weight at most with respect to 100 parts by weight of the total amount of the thermoplastic resin and the auxiliary agent). Nevertheless, when viewed transversely to the extrusion direction, it is believed that the above dispersed morphology is formed with the resin as the dispersed phase and the water as the continuous phase. In the present invention, from the W / O type to the phase inversion to the above-mentioned dispersed form, water is supplied into the cylinder 10 at a plurality of points to disperse the water evenly in the thermoplastic resin. The phase inversion is performed well, and it is possible to obtain a uniform fiber having a small diameter. When the melt-kneaded product is finally spun out, the condition that the contained water is not substantially flushed, that is, the rapid extrusion so that the water is flushed as in the conventional flash spinning method, should be stopped. . If the melt-kneaded product is rapidly extruded in a highly fluidized state as in the flash spinning method, the water molecule film attached to the single fibers will evaporate, the single fibers will fuse together, and water will be taken in as bubbles in the resin. The desired fiber bundle cannot be obtained by foaming. More specifically, the spinning temperature is lowered to around the melting point, and the spinning is carried out within the range where the fluidity is not lost. The water content of the obtained fiber bundle is substantially the same as the water content present in the melt, but some water may evaporate during spinning. Furthermore, in the final fiber obtained by defibrating the fiber bundle, the water content may be evaporated and the water content may be substantially zero. <Properties of Synthetic Fiber> The spun product according to the method of the present invention is such that a large number of uniform thermoplastic resin ultrafine fibers having a substantially circular cross-sectional shape and a substantially indefinite length of 200 μm or less are twisted in a substantially parallel state. However, it is a bundled ultrafine fiber bundle, and the ultrafine fibers composing the fiber bundle are partially bonded to each other.
Immediately after being spun, a water molecule film is present on the surface of each single fiber. <Defibration> The defibration of the ultrafine fiber bundle having such a property is performed by using the various defibration devices described above. However, according to the means for blowing the gas toward the ultrafine fiber bundle, the fiber bundle coming out of the orifice 3 is discharged. The fiber bundle is disentangled by blowing away the air with the gas.
Further, since the water molecule film attached to the surface of each single fiber immediately after spinning is evaporated, the defibrated fiber aggregate becomes almost dry. By defibrating the fiber bundle, it can be defibrated in the state of single fibers or in the form of an aggregate in which single fibers are entangled with each other. <Use of Fiber after Disentanglement> The fiber after disentanglement is used as a binder for water absorbent cotton in a diaper, as a binder for non-woven fabric, as a binder for pulp for papermaking, and the like. [Effects of the Invention] In the present invention, water is supplied into the cylinder at a plurality of points to disperse the water evenly in the thermoplastic resin, so that the phase inversion necessary for forming the fiber bundle is satisfactorily performed. As a result, uniform fibers having a small diameter can be obtained. Therefore, the final ultrafine fiber bundle can also be made homogeneous, and the cotton-like fiber aggregate obtained by defibrating it must also be made homogeneous with no variation in fiber thickness. Therefore, it can be easily used for various purposes. [Examples and Comparative Examples] <Example 1> An ultrafine fiber bundle was spun and defibrated under the following conditions. (A) Apparatus As the extruder 1, a single-screw extruder with an inner diameter of 20φ and L / D = 36 (intermediate mixing type manufactured by Ikegai Tekko Co., Ltd.) was used. As shown in FIG. 4, the water inlet 11 is located immediately upstream of the cylinder 10 immediately after the resin is completely melted.
A pair of inlets 11 are provided so as to face each other on the left and right. The orifice 3 of the die 2 is, as shown in FIG. 3 (b), four orifices having a diameter of 0.5 mmφ arranged side by side. Further, the angle of the nozzle opening 6 from which the compressed air is ejected is the upper surface inclination angle θ inside the nozzle opening 6 with respect to the front surface of the die 2 which is a vertical surface.
Is 40 degrees, and the lower surface inclination angle ψ inside the nozzle opening 6 is 45 degrees, and the compressed air ejected from this nozzle opening 6 is blown onto the ultrafine fiber bundle at an angle of about 45 degrees from the vertical and horizontal directions. To be The screen mesh 5 interposed between the screw outlet and the orifice 3 of the die 2 is not used. (B) Blended low density polyethylene (Mitsui Petrochemical Industry Co., Ltd.
96 parts by weight of Mirason FL-60) Acid-modified low molecular weight polyethylene (Mitsui Petrochemical Co., Ltd., trade name Mitsui High Wax 2203A, molecular weight 270
4 parts by weight of 0, density 0.93 g / cm ³ , acid value 30 kOHmg / g) Nonionic surfactant (Kao Corporation trade name
Emulgen 430 Polyoxyethylene oleyl ether H
30 parts by weight of 20% aqueous solution of LB = 16.2) (C) Operating conditions Temperature of each part of extruder C ₁ ·· 120 ° C C ₂ ·· 155 ° C C ₃ ·· 155 ° C C ₄ ·· 120 ° C Die temperature 95 ℃ Compressed air temperature 95 ° C Compressed air pressure 4kg / cm ² · G Extrusion amount 1kg / Hr Water injection amount 2 equally divided (d) Results Randomly, as shown in the photograph shown in Fig. 6 and Table 1. Chose
As a result of observing the diameter of 50 fibers with a microscope, the fiber diameter is 100
A fiber bundle with a very good texture was obtained, in which nothing exceeding μ was obtained. <Embodiment 2> As shown in FIG. 5, one water inlet 11 is provided on the upstream side of the cylinder 10 immediately after the resin is completely melted.
The conditions are the same as in Example 1 except that a total of two locations, one at the downstream intermediate mixing section, are provided. As a result, as shown in Table 1, fiber bundles having a fiber diameter of more than 100μ and having very few textures were obtained. <Comparative Example 1> The conditions are the same as those in Example 1 except that only one of the two water inlets in FIG. 4 is used. As shown in Table 1, the diameter of the single fiber constituting the obtained fiber bundle was uneven and not uniform.

[Brief description of drawings]

FIG. 1 is a sectional view of an extruder used in the present invention, and FIG.
3 is a sectional view of the die and the defibrating device, and FIG. 4 is a sectional view of the extruder used in Example 1, and FIG. 5 is a sectional view of the extruder. A sectional view of the extruder used in Example 2 and FIG. 6 are photographs showing the shape of the fiber obtained in Example 1. 1 ... Screw type extruder, 2 ... Die, 3 ... Orifice, 11 ... Water inlet.

Claims (2)

[Claims] 1. A screw type extruder, which melts and kneads a thermoplastic resin, water, and an auxiliary agent for assisting the dispersion of water in the thermoplastic resin, and is formed in the extruder during the melting and kneading. In the method for producing an ultrafine fiber bundle that is extruded from a die, the water inlet is provided at a plurality of positions of the screw type extruder, water is injected from each inlet, and water is added to the thermoplastic resin at a plurality of points. A method for producing an ultrafine fiber bundle, which comprises dispersing. 2. A method of defibrating by spraying gas from at least one direction of a die toward an ultrafine fiber bundle.
Item 2. A method for producing an ultrafine fiber bundle according to item.