JPH0655964B2 - Method for defibrating ultrafine fiber bundles - Google Patents

Description

Detailed Description of the Invention

TECHNICAL FIELD The present invention relates to a method for defibrating an ultrafine fiber bundle, and more particularly to a method for defibrating a novel ultrafine fiber bundle previously proposed by the applicant of the present application into a short fiber shape. [Prior Art] The applicant of the present application has previously disclosed in Japanese Patent Application No. 59-198669 that a large number of thermoplastic resin ultrafine fibers having a substantially circular cross-sectional shape and a substantially indefinite length of 200 μm or less are bundled in a substantially parallel state. An ultrafine fiber bundle having the above-mentioned shape, characterized in that the ultrafine fiber bundles constituting the fiber bundle are partially bonded to each other is proposed. [Problems to be solved by the invention] This ultrafine fiber bundle is melted in a screw type extruder by adding a thermoplastic resin, water and an auxiliary agent for assisting water to be dispersed in the thermoplastic resin. When kneaded, it is formed into a fiber bundle naturally in the extruder during the melting and kneading, and it is apparently continuous in the state of being extruded from the die of the extruder, and the fibers are bundled together. Therefore, in order to use it for a certain purpose, it is necessary to defibrate it. A first object of the present invention is to provide a method capable of efficiently defibrating the ultrafine fiber bundle. On the other hand, this ultrafine fiber bundle, like the conventional type of ultrafine fiber bundle, extruded the molten polymer from the die of the extruder,
It is not necessary to draw and spin, and the ultrafine fiber bundle has already been formed at the time of being extruded from the die. Therefore, the secondary processing of the ultrafine fiber bundle is possible at this time. A second object of the present invention is to utilize such a point to defibrate the ultrafine fiber bundle at the time of being extruded from the die, thereby simplifying and accelerating the fibrillating process of the ultrafine fiber bundle. Especially. [Means for Solving Problems] The present invention has the following technical means in order to solve the above technical problems. That is, the present invention is a screw type extruder 1 in which a thermoplastic resin, water, and an auxiliary agent for assisting the dispersion of water in the thermoplastic resin are melted and kneaded, and the extruder is melted and kneaded during the melting and kneading. 1 is a method of defibrating an ultrafine fiber bundle that is extruded from an orifice 3 of a die 2 formed in a die 1. When the ultrafine fiber bundle is extruded from an orifice 3 of a die 2 of an extruder 1, an orifice is directed toward the ultrafine fiber bundle. 3 is defibrated by blowing gas from at least one direction, and preferably defibrated into short fibers. [Operation] From the spinning by the screw type extruder to the defibration by the gas, the thermoplastic resin, the auxiliary agent, and the water for forming the ultrafine fiber bundle will be described below. <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, 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-olefin with conjugated or non-conjugated diene such as butadiene copolymer and ethylene-ethylden norbornene copolymer 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
Polyamides such as 2 and the like, thermoplastic polyesters such as polyethylene terephthalate and polybutylene terephthalate, polycarbonates, polyphenylene oxides, polysulfones, polyphenylene sulfides, polyether ether ketones and the like, and mixtures thereof can be exemplified. 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 such that water is gradually dispersed in the thermoplastic resin to cause phase inversion when the thermoplastic resin and water are kneaded. 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 believed that such a phenomenon caused by melt-kneading is a cause of manufacturing 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 its 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% or even 80-97% partially saponified polyvinyl alcohol is convenient. When these auxiliary agents are kneaded together with the above-mentioned thermoplastic resin and water, the auxiliary agent is first kneaded into the thermoplastic resin uniformly, and subsequently the auxiliary agent is swollen by water to divide the thermoplastic resin. 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 melt viscosity is preferable. The resin that is the standard of compatibility is the solubility parameter (Sp
Value), and the difference in Sp value is preferably within 2 (Cal / cm ³ ) ^1/2 , particularly within 1 (Cal / cm ³ ) ^1/2 . The Sp value is a value defined as the 1/2 power value 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 are calculated by DWVan.Klevelen “Properties o
f Polymers ”(Elsevier, 1972) It can be calculated from 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 derived from an unsaturated carboxylic acid or a derivative thereof, but it does not swell in water because the base resin is sparingly 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. Among them, unsaturated carboxylic acid salt is contained in 1 g of the 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 contains 0.1 to 5 millimolar equivalents in terms of group,
In order to produce the modified resin of this aspect, a thermoplastic resin previously modified with an unsaturated carboxylic acid or an anhydride or ester thereof is added to a basic substance, that is, an alkali metal, an alkaline earth metal, ammonia, an amine or the like in water. Neutralize or saponify with substances that act as bases, alkali metal oxides, hydroxides, weak acid salts, hydrides, alkaline earth metal oxides, hydroxides, weak acid salts, hydrides, alkoxides of these metals, etc. An example of the method is as follows. 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,
Strontium hydroxide, barium hydroxide, sodium hydride, potassium hydride, calcium hydride, weak acid salts of alkali metals and alkaline earth metals include sodium carbonate, potassium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, calcium hydrogen carbonate. Examples of the compounds of 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 carboxylate ester group neutralized or saponified with a basic substance, sodium carboxylate, alkali metal carboxylate such as potassium carboxylate, ammonium carboxylate are preferable, and potassium carboxylate is 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 an anionic surfactant, a cationic surfactant, a nonionic surfactant, and a zwitterionic surfactant. In particular, the anionic surfactant and the nonionic surfactant are the above A and / or Combined with B, it is preferable because ultrafine fibers having a diameter of 100 μ or less and generally less than 50 μ 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 anionic surfactant is mixed well, and ultrafine fibers having a smaller diameter can be obtained. Any such organic compound may be used as long as it reacts with a basic substance to form an anionic surfactant, and preferred examples thereof include primary higher fatty acids, secondary higher fatty acids,
Primary higher alcohol sulfate, 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,
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 them, 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 having a viscosity of less than 1 g / 10 min, the effect is remarkably exhibited, but of course, it is also applicable to a resin having a low melting gap viscosity, that is, an 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 modes of use of the auxiliary agent, for example, A or B alone, A and B in combination, A and / or B and C in combination, A and / or B and D in combination. , A and / or B and C and D in combination, and A and E in combination. More preferably, a neutralized or saponified modified resin (B) is used when the fiber diameter is relatively large (approximately 50 μ or more), and a neutralized or saponified modified resin (B) is used when the fiber diameter is thin (less than approximately 50 μ). And a surfactant (C), especially when aiming for a neutral ultrafine fiber, select a nonionic surfactant as (C) among the above combinations, or a ultrafine fiber of a resin with a high melting viscosity. When using a neutralized or saponified modified resin (B) and a surfactant (C) and an organic solvent (D), or when the fiber bundle itself is strongly solidified, a water-soluble resin (A) Or use. The amount of the auxiliaries used varies depending on the type of the thermoplastic resin or the type of the auxiliaries to be made into ultrafine fiber bundles, but is generally 75 to 98 parts by weight of the thermoplastic resin, particularly 80 to 95 parts by weight and the auxiliaries 2 -25 parts by weight, especially 5 to 20 parts by weight (however, the total of both is 100 parts by weight). Particularly when a thermoplastic resin, a modified resin neutralized or saponified and a surfactant are used as a preferred embodiment of the present invention, 75 to 98 parts by weight, 1 to 20 parts by weight, and 1 to 5 parts by weight (total is 100 parts by weight.) Particularly, 80 to 95 parts by weight, 3 to 16 parts by weight, and 2 to 4 parts by weight are mixed. Further, 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 relative 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. Various methods can be used for adding water, for example, a method of adding water together with a thermoplastic resin and an auxiliary agent before melt-kneading, and a method of gradually adding water during melt-kneading.
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. <Production of Ultrafine Fiber Bundle> To produce an ultrafine fiber bundle, the thermoplastic resin, the auxiliary agent and water are melt-kneaded and then spun through an orifice such as a spinning nozzle. As a result, it is possible to spin a single fiber bundle in which a large number of ultrafine fibers having a diameter of 200 μm or less per one orifice hole 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 should be noted that according to the present invention, a fiber bundle is formed for each orifice. 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 the parallel directions. Explaining this point, under the melt-kneading conditions in which a shearing force acts in a three-dimensional direction, such as melt-kneading in a twin-screw extruder, water is a continuous phase and so-called O / P resin is a dispersed particle.
W-type phase inversion easily occurs and a continuous fibrous resin cannot be obtained. Therefore, as the extruder to be used in the method of the present invention, a single-screw extruder suitable for shearing and kneading in only the two-dimensional direction is preferable. However, it goes without saying that even a multi-screw extruder can be used as long as it is improved so as to be suitable for the present invention. Formed by the method of the present invention, in the dispersed state of the melt gap, the melt gap resin is a large number of independent columnar phases oriented in the extrusion direction,
Water is present in the form of a packed phase that fills the interstices of these numerous 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 melting resin is a dispersed phase and water is a continuous phase, but both the melting resin and water are in the extrusion direction. It is considered to be virtually continuous. That is, the water added to the system is gradually taken into the melting resin by the shearing force of the kneading and the action of the auxiliary agent, and at first, the water is dispersed in the thermoplastic resin (W / O).
Type) dispersion. Furthermore, when the shearing force in the two-dimensional direction is continuously applied, the amount of dispersed water is small this time (3 to 40 parts at most for 100 parts by weight of the total amount of the thermoplastic resin and the auxiliary agent).
However, the above dispersion form (O / W type) in which the resin is the dispersed phase and the water is the continuous phase is formed when viewed in the transverse direction with respect to the extrusion direction. Seem. The meaning of spinning through the orifice is that the resin just before phase inversion is fibrous with water as the boundary phase as described above, but as it is, many of these fibrous resins are randomly mixed. This is because it is necessary to align the fibrous resins by orienting them in a certain direction. What is different from the conventional melt-spinning method here is that no matter what the shape of the orifice is, the melt-kneaded product that passes through the orifice and is discharged from one orifice contains a large number of ultrafine fibers (diameter of 200 μ or less). ) Comes out as a fiber bundle that is bundled substantially parallel to the extruding direction. When the melt-kneaded product is finally spun out, it should be stopped under the condition that the contained water does not substantially flush, that is, the rapid extrusion so that the water flushes as in the conventional flash spinning method. is there. If the melt-kneaded product is rapidly extruded in a highly fluidized state as in the flash spinning method, the water molecule film adhering to the single fibers will evaporate and the single fibers will fuse together, or the water will form bubbles in the resin. The target fiber bundle cannot be obtained because it is taken up by and foamed. More specifically, the spinning temperature is lowered to near the melting point of the resin to increase the viscosity within the range where the resin does not impair the fluidity, and spinning is carried out in the usual manner of plastic extrusion molding. 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. <Device used in the present invention>

[Extruder]

The extruder used in the present invention is preferably the single-screw extruder 1 from which the shearing force does not act in the direction parallel to the extrusion direction of the molten resin for the reasons described above. As the screw shape, an intermediate mixing type screw is preferably used. Then, for example, a high-pressure plunger pump is connected as the pump 4 for injecting water in the middle of the extruder, for example, immediately before the intermediate mixing section. The water may be injected not only immediately before the intermediate mixing section but also in stages at the resin carrying-in section, immediately after the intermediate mixing section, the shearing / kneading section, the measuring section and the like.

[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. When using a die as shown in Fig. 1, the orifice diameter is 0.1 to 3 mm.
φ, preferably 0.3 to 1.5 mmφ.

[Disentanglement device]

As shown in FIG. 2, a device for defibrating the fiber bundle extruded from the orifice 3 of the die 2 is such that a gap-like nozzle port 6 is provided around the orifice 3 of the die 2 to surround the orifice 3. From the above to the ultrafine fiber bundle, or as shown in FIG. 3, nozzle openings 6 are provided above and below the orifice 3, respectively, and gas is blown from these nozzle openings 6 toward the ultrafine fiber bundle from above and below. What can be illustrated. In this case, the distance between the nozzle openings 6 is 0.1 to
It is 4 mm, preferably 0.2-2 mm. Further, the gas spraying angle from the nozzle port 6 is 20 to 90 degrees, preferably 40 to 80 degrees with respect to the ultrafine fiber bundle. Further, the gas to be ejected may be any gas such as nitrogen and oxygen, but air is most preferable in terms of safety and economy. Then, the air is ejected from the nozzle port 6 as compressed air by the air compressor 7. In this case, the air pressure may be 1 kg / cm ² · G or more, preferably 2 kg / cm ² · G or more, and there is no upper limit. The temperature may be such that the tip of the orifice of the air temperature die is cooled and the resin is not clogged at the tip of the orifice. For example, the melting point of the resin is ± 50 ° C, preferably ± 20 ° C. <Properties of Synthetic Fiber> The spun product produced by the method of the present invention has a substantially circular cross-sectional shape and a substantially indefinite length of 200 μm or less, most of which is 100 μm or less It is a bundle of ultrafine fibers without being broken, 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 properties is performed by blowing a gas toward the ultrafine fiber bundle using the defibration device. The fiber bundle is disentangled by blowing away the fiber bundle coming out of the orifice 3 together with the gas. At this time, the fiber length is changed from several cm to several mm by changing and adjusting the linear velocity of the gas. Can be changed in length. By defibrating the fiber bundle, it can be defibrated in a single fiber state or in the form of an aggregate in which the single fibers are entangled with each other. In addition, since the water molecule film attached to the surface of each single fiber immediately after spinning is evaporated, the aggregate of disentangled fibers becomes almost dry. <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 a non-woven fabric, as a binder for papermaking pulp, and the like. EFFECTS OF THE INVENTION According to the present invention, a large number of thermoplastic resin ultrafine fibers having a substantially circular cross-sectional shape and a diameter of 200 μ or less, which are substantially indefinite, are bundled in a substantially parallel state, and each bundled ultrafine fiber is Comrades can efficiently disintegrate ultrafine fiber bundles, which are partially bonded, by blowing gas into single fibers. Moreover, since only the gas is blown, the device itself and therefore the defibration process can be simplified and the equipment can be made inexpensive. Further, in the manufacturing process of the ultrafine fiber bundle, the gas evaporates the moisture that inevitably adheres to the surface of the single fibers constituting the ultrafine fiber bundle, so a new drying step of the fiber is not required, and in this respect also It can be simplified. [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 KK) was used. As shown in FIG. 2 (b), the orifice 3 of the die 2 is a laterally long hole when viewed from the front and has a size of 0.5 mm long and 2 mm wide. Further, the nozzle port 6 for ejecting compressed air is the orifice 3
It is formed in a circular shape surrounding the circumference of, and air can be jetted from the entire circumference toward the ultrafine fiber bundle pushed out from the orifice 3. And the angle of the nozzle mouth 6 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 (this is true even in the left and right parts inside the nozzle opening 6). Similarly, the compressed air ejected from the nozzle port 6 is blown to the ultrafine fiber bundle from the vertical and horizontal directions at an angle of approximately 45 degrees. The screen mesh 5 interposed between the screw outlet and the orifice 3 of the die 2 is # 100, # 200, # 300, # 20.
There are 5 cards, 0 and # 100. (B) Blended low density polyethylene (Mitsui Petrochemical Industry Co., Ltd.
96 parts by weight of Milason 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 ℃ Compressed air pressure 4kg / cm ² · G Extrusion amount 1kg / Hr (d) Result Fiber with diameter of 1-40μm and fiber length of 0.1-80mm is the fourth
As shown in the photograph in the figure, it was obtained in a defibrated state. Comparative Example 1 Under the same conditions as in Example 1, when compressed air was not blown to the ultrafine fiber bundle, as shown in the photograph of FIG.
A continuous fiber bundle in which μm fibers were densely bundled was obtained. <Example 2> As shown in FIG. 3 (b), the orifices 3 of the die 2 are four pieces having a diameter of 0.5 mmφ arranged side by side, and the screen mesh 5 has # 80, # 100, # 200. , # 300, # 500, # 10
The conditions are the same as those in the first embodiment except that the number of sheets is 00, # 500, # 300, # 200, # 100 and # 80. The result is that the fiber diameter is 1 to 40μ as shown in the photograph in FIG.
m and a fiber length of 50 μm to 10 mm were obtained in a fibrillated state. <Comparative Example 2> When compressed air was not blown to the ultrafine fiber bundle under the same conditions as in Example 2, the fiber diameter was 1 to 40 μm as shown in the photograph in FIG.
m monofilaments were apparently obtained as continuous strands densely assembled to a thickness of about 1 mm.

[Brief description of drawings]

FIG. 1 is a sectional view of an extruder and a defibrating device showing an embodiment of the present invention, FIGS. 2 (a) and 2 (b) are sectional views and a front view of a defibrating device portion, and FIG. 3 (a) ( b) is a sectional view and a front view showing another defibrating device, FIG. 4 is a photograph showing the shape of the fiber obtained in Example 1, and FIG. 5 is a photograph showing the shape of the fiber obtained in Comparative Example 1. FIG. 6 is a photograph showing the shape of the fiber obtained in Example 2, and FIG. 7 is a photograph showing the shape of the fiber obtained in Comparative Example 2. 1 ... Screw type extruder, 2 ... Die, 3 ... Orifice.

Claims (3)

[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. This is a method of defibrating the ultrafine fiber bundle that is pushed out from the orifice of the die, and when this ultrafine fiber bundle is pushed out from the orifice of the die of the extruder, a gas is blown toward the ultrafine fiber bundle from at least one direction of the orifice. A method for defibrating an ultrafine fiber bundle, which is characterized by defibrating by fibrillation. 2. The method for defibrating ultrafine fiber bundles according to claim 1, wherein the gas is air. 3. The method for defibrating an ultrafine fiber bundle according to claim 1, wherein the ultrafine fiber bundle is defibrated into a short fiber shape.