JPH0372731B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to ultrafine fiber bundles. More specifically, the present invention relates to a new shape of ultrafine fiber bundle. [Prior Art] Various proposals have been made regarding bundles of ultrafine fibers having a diameter of several hundred microns or less and techniques for producing the same. For example, the super draw method
No. 617, etc.), flat spinning method (Special Publication No. 1973-),
11851, etc.), a method in which ultrafine fibers are produced using a jet spinning method, etc., and then a large number of ultrafine fibers are bundled using a binder component, or a method in which a large number of ultrafine fibers are mechanically twisted and bundled (in the case of ultrafine fibers, this method is practically difficult). However, when using the super draw method, the types of resins that can be used are limited, and a special stretching process is required after spinning, resulting in large-scale equipment. Although the flash spinning method can be applied to many types of resin, it can only produce short fibers, making it difficult to make continuous fibers. Moreover, since the solvent is scattered during the flashing process, this is not a preferable method from the viewpoint of safety and working environment.
Jet spinning requires a specially shaped spinneret and has the same problems as flash spinning. Above all, these methods require special secondary processing to produce fiber bundles, but secondary processing of ultrafine fibers is extremely difficult due to their weak fiber strength. For this reason, a technology to manufacture fiber bundles by spinning fibers with a sea-island structure using two types of resin components, and then extracting and removing the sea components to leave the ultrafine fibers of the island components has been developed. It has been proposed as a blend fiber dissolution method or a polymer mutually aligned fiber dissolution method. However, in most of the polymer blend fiber dissolving methods, the length of the resin serving as the island component in the longitudinal direction is short, and therefore it is difficult to form continuous fibers. Inside is a special public service from 1974.
As seen in No. 21167, an attempt to produce continuous fibers using this method has been proposed, but the resulting ultrafine fiber bundles are intricately intertwined and intertwined. On the other hand, in the latter polymer mutual array fiber dissolution method, since the island components are long and continuous in the longitudinal direction, it is possible to produce bundles of continuous ultrafine fibers, and the resulting fiber bundles can also be made of ultrafine fibers. Although a plurality of fibers are arranged independently and in parallel, a special structure is required for the spinneret, making the equipment complicated and expensive. Moreover, in all of these methods, ultrafine fiber bundles can only be obtained after a post-processing step is performed to extract the sea components. [Problems to be Solved by the Invention] Against this background, the present inventors have conducted extensive research in an effort to develop a technology for manufacturing ultrafine fiber bundles without requiring any special secondary processing or post-processing steps. As a result, we have completed a new spinning technology that is unimaginable with conventional common sense, that is, a spinning technology in which the fiber itself that is spun from a single spinning hole is already a bundle of ultra-fine fibers. This led to obtaining ultrafine fiber bundles. By the way, as prior art examples disclosing fiber bundles or related prior art examples, Utility Model Publication No. 50-30438, Japanese Patent Publication No. 46-32458, and Japanese Patent Application Laid-Open No. 46-3906 are known. Utility Model Publication No. 50-30438 describes split fibers made of a linear material made of a mixed resin of polyolefin resin and polyvinyl alcohol resin, but the cross-sectional shape of the fibers is non-uniform and has fluff. (Page 2 of the publication, right column, lines 15 to 16). Further, Japanese Patent Publication No. 46-32458 describes a fibrous material that is fibrillated by high-speed airflow, and there is a description that it is made into a sheet, but there is no description of the ultrafine fiber bundle itself. Furthermore, JP-A No. 46-3906 discloses that polyolefin fibers are isolated and produced by mechanically filing a fibrous gel containing fibers with a diameter of 1 to 20 μm and microscopic fibers of 1 μm or less from olefin. The method is described (bottom left and right columns of page 2 of the publication). Here, the term fibrous gel is defined as "the fibrous structure of fibrous polyolefin defining a network structure in which capillary spaces filled with a reaction medium are interconnected" (Page 3 of the publication). Lines 9 to 12 of the upper left column, the characters in the ○ part are illegible). In addition, "refiling" means "applying shearing force to the fibrous gel" (Page 9, bottom right column 12 of the publication).
line 14). Therefore, the fibers obtained are, for example, 10 to 15 mm, or less than 0.05 mm (lines 1 to 3, upper right column, page 7 of the publication). The publication describes various properties of the obtained fibers, but these are different from the properties of the ultrafine fiber bundle that is intended to be obtained in the present application. The present invention aims to provide an ultrafine fiber bundle that has no cut surface on the surface of each fiber and is substantially free of fuzz, unlike such conventional fibers or fiber bundles. Take it as a challenge. [Means for Solving the Problems] In other words, the present invention has a method in which a large number of thermoplastic resin ultrafine fibers with a diameter of 200 μm or less and a substantially circular cross-sectional shape and a substantially indefinite length are substantially equivalent to single fibers formed singly. , an ultrafine fiber bundle that is bundled in a substantially parallel state, and is characterized in that the ultrafine fibers constituting the fiber bundle are partially bonded to each other. A suitable method for producing this ultrafine fiber bundle is to melt-knead a thermoplastic resin, water and an auxiliary agent that assists in dispersing the water into the thermoplastic resin, and then spin the fibers from an orifice. , there is a method for producing an ultrafine fiber bundle characterized by spinning a fiber bundle in which a large number of ultrafine fibers with a diameter of 200 μm or less are bundled in a substantially parallel state from one orifice hole. [Function] The ultrafine fiber bundle of the present invention will be explained below according to its manufacturing method. <Thermoplastic resin> The thermoplastic resin that is the raw material of the present invention may be any resin, whether crystalline or amorphous, as long as it is water-insoluble and can be made into fibers.For example, high-pressure low density polyethylene, medium-low pressure process 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,
Random or block copolymers of α-olefins such as 1-hexene and 1-decene, ethylene and
Butadiene copolymer, ethylene/nylidenenorbornene copolymer, ethylene/propylene/butadiene ternary copolymer, ethylene/propylene/dicyclopentadiene ternary copolymer, ethylene/propylene/1,5-hexadiene ternary copolymer polymer,
Copolymers of two or more α-olefins and conjugated or non-conjugated dienes, such as ethylene/propylene/ethylidene norbornene ternary copolymers, ethylene/acrylic acid copolymers, ethylene/vinyl acetate copolymers, ethylene/vinyl acetate copolymers, etc. Vinyl alcohol copolymers, ethylene/vinyl compound copolymers such as ethylene/vinyl chloride copolymers, polystyrene, acrylonitrile/styrene copolymers, acrylonitrile/butadiene/styrene copolymers, methyl methacrylate/styrene copolymers, Styrenic resins such as α-methylstyrene/styrene copolymer, polyvinyl chloride, polyvinylidene chloride, vinyl chloride/vinylidene chloride copolymer, vinyl polymers such as polymethyl acrylate, polymethyl methacrylate, nylon 6, Polyamides such as nylon 66, nylon 610, nylon 11 and nylon 12, thermoplastic polyesters such as polyethylene terephthalate and polybutylene terephthalate, polycarbonate, polyphenylene oxide, polysulfone, polyphenylene sulfide, polyether ether ketone, etc. Examples include mixtures. In the present invention, the various resins listed above can be used, but a major feature is that low-density polyethylene and ultra-high molecular weight polyethylene, which have conventionally been difficult to make into ultra-fine fibers, can be used in the same way as other resins. be. <Auxiliary agent> The auxiliary agent, which is another component of the present invention, is a substance that gradually disperses into the thermoplastic resin during kneading of the thermoplastic resin and water, causing phase inversion. Its main function is to produce an aqueous dispersion in which the continuous phase is water, such as a thermoplastic resin dispersed in water. It is thought that causing such a phenomenon by melt-kneading is the cause of producing ultrafine fiber bundles all at once. That is, by simply melt-kneading a thermoplastic resin and water without using an auxiliary agent, an ultrafine fiber bundle cannot be produced, and therefore the object of the present invention cannot be achieved. The general concept of an auxiliary agent that exhibits this type of action is that it has both a hydrophilic group and a lipophilic group in its molecule, and more specifically, it consists of the following compounds alone or in combination of two or more. used. (A) Water-swellable or water-soluble thermoplastic resin (B) Slightly water-soluble or water-insoluble thermoplastic resin modified with unsaturated carboxylic acids (C) Surfactant (used in combination with A and/or B) ) (D) Organic solvent (used in combination with A and/or B) (E) Others (used in combination with A and/or B) These will be explained in detail below. (A) Water-swellable or water-soluble thermoplastic resin that swells or dissolves in water (infinite swelling)
Examples include polyvinyl alcohol, methylcellulose, carboxymethylcellulose or its sodium salt, polyacrylic acid, sodium polyacrylate, and polyacrylic acid amide. Among these, polyvinyl alcohol, particularly partially saponified polyvinyl alcohol with a degree of saponification of 65 to 98% and more preferably 80 to 97%, is advantageous. When these auxiliary agents are kneaded together with the aforementioned thermoplastic resin and water, the auxiliary agents are first uniformly kneaded into the thermoplastic resin, and then the auxiliary agents are swollen by the water and the thermoplastic resin is divided. Then, water penetrates further into the interior, swelling the auxiliary agent present inside and promoting fragmentation of the thermoplastic resin, resulting in an aqueous dispersion in which the thermoplastic resin is finely fragmented by water. It is thought that it gives The characteristics of this type of auxiliary agent are that the types of thermoplastic resins that can be applied to it are smaller than those of the auxiliary agents described below, and that if the manufactured ultrafine fiber bundle is left alone, the ultrafine fibers will gradually break down over time. The result is a fiber bundle that looks like it is firmly adhered, and a fiber bundle that also has hydrophilic properties. (B) Poorly water-soluble or water-insoluble thermoplastic resins modified with unsaturated carboxylic acids. Products obtained by graft copolymerization or block copolymerization of unsaturated carboxylic acids with poorly water-soluble or water-insoluble resins, or random copolymerization in the resin. In particular, those having good compatibility with the thermoplastic resin of the fiber raw material and those having a low melt viscosity are preferred. The index that serves as a guideline for compatibility is the solubility parameter (Sp value), and the difference in Sp value is 2 (Cal/cm ³ ) ^1/2
It is preferably within 1 (Cal/cm ³ ) ^1/2 . The Sp value is defined as the 1/2 power of the cohesive energy density, and the contribution value Vi to the molar volume of the atomic group and the cohesive energy En of the atomic group are
DWVan.Klevelen“Properties of Polymers”
(Elsevier, 1972) and can be calculated from the formula Sp=(ΣEni/ΣVi) ^1/2 (Cal/cm ³ ) ^1/2 . Further, examples of the material having a low melt viscosity include wax-like materials having a small molecular weight. Although this modified resin has a carboxy group derived from an unsaturated carboxylic acid or a derivative group thereof, and is therefore hydrophilic, it does not swell in water because the base resin is poorly water-soluble or water-insoluble. In addition, the unsaturated carboxylic acid unit in the modified resin is
Examples include unsaturated carboxylic acids, esters thereof, and unsaturated carboxylic acid salts obtained by neutralizing or saponifying these. Among them, unsaturated carboxylic acid salts are present in 1 gram of polymer. 0.1 to 5 mmol equivalent in terms of base, especially 0.2 to 4
Those containing millimolar equivalents are preferred. The modified resin is a copolymerization of the monomers constituting the poorly water-soluble or water-insoluble thermoplastic resin mentioned above and unsaturated carboxylic acids, and the unsaturated carboxylic acids include (meth)acrylic acid, maleic acid, and fumaric acid. , tetrahydrophthalic acid, itaconic acid, citraconic acid, crotonic acid, isocrotonic acid, nadic acid (endocys-bicyclo[2,2,1]hept-5-ene-2,3-dicarboxylic acid), maleic anhydride, citraconic anhydride Unsaturated carboxylic acids such as acids or their anhydrides, monoesters such as methyl, ethyl, propyl, etc. of the above unsaturated carboxylic acids, nister compounds such as diesters, and unsaturated carboxylic acids such as alkali metal salts, alkaline earth metal salts, ammonia salts, etc. Examples include saturated carboxylates. Of course, it will be obvious to those skilled in the art that instead of copolymerizing a plurality of monomer components, the above-mentioned unsaturated carboxylic acids may be graft-polymerized or block-polymerized onto a thermoplastic resin such as an olefin resin. As mentioned above, the preferred embodiment of this modified resin is that the unsaturated carboxylate is present in 1 g of the polymer. In order to produce the modified resin of this embodiment, a thermoplastic resin that has been modified in advance with an unsaturated carboxylic acid, its anhydride, or its ester is treated with a basic substance, i.e. Alkali metals, alkaline earth metals, substances that act as bases in water such as ammonia and amines, alkali metal oxides, hydroxides, weak acid salts, weak acid salts, hydrides, alkaline earth metal oxides and hydrides Examples include methods of neutralization or saponification using weak acid salts, hydrides, alkoxides of these metals, and the like. Specific examples of such basic substances are shown below. (1) Examples of alkali metals include sodium, potassium, and alkaline earth metals.
Examples include calcium, strontium, barium, (2) Amines include inorganic amines such as hydroxylamine and hydrazine, methylamine, ethylamine, ethanolamine, and cyclohexylamine, (3) oxides and hydroxides of alkali metals and alkaline earth metals. Examples of compounds and hydrides include sodium oxide, sodium peroxide, potassium oxide, potassium peroxide, calcium oxide, strontium oxide, barium oxide, sodium hydroxide, potassium hydroxide, calcium hydroxide, strontium hydroxide, and barium hydroxide. , sodium hydride, potassium hydride, calcium hydride, (4) Weak acid salts of alkali metals and alkaline earth metals include sodium carbonate, potassium carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, calcium hydrogen carbonate, sodium acetate,
Examples of the compounds of potassium acetate, calcium acetate, (5) 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 that has been neutralized or saponified with a basic substance, alkali metal carboxylates such as sodium carboxylate and potassium carboxylate, and ammonium carboxylate are suitable, and potassium carboxylate is especially preferred. preferable. (C) Surfactant A surfactant is not used alone as an auxiliary agent, but is used in combination with A and/or B above.
The surfactant used may be an anionic surfactant, a cationic surfactant, a nonionic surfactant, or an amphoteric surfactant, but
In particular, the anionic surfactant and the nonionic surfactant, together with the above A and/or B,
This method is suitable because ultrafine fibers of 100μ or less, generally less than 50μ, can be produced. Here, the anionic surfactant includes not only those that are in the form of anionic surfactants from the beginning, but also those that react with the basic substances mentioned in (1) to (5) above and eventually become anionic surfactants. It also includes organic compounds such as In other words, it is better to melt-knead the thermoplastic resin, A and/or B, and the organic compound, and then add a basic substance and continue melt-kneading to convert the organic compound into an anionic surfactant. The anionic surfactant is well mixed and ultrafine fibers with a smaller diameter are obtained. Any organic compound may be used as long as it reacts with a basic substance to become an anionic surfactant, and preferred examples include primary higher fatty acids, secondary higher fatty acids, and primary higher alcohol sulfuric esters. , secondary higher alcohol sulfuric acid ester, primary higher alkyl sulfonic acid, secondary higher alkyl sulfonic acid, higher alkyl disulfonic acid, sulfonated higher fatty acid, higher fatty acid sulfuric ester, higher fatty acid ester sulfonic acid, higher alcohol ether sulfuric acid Examples include esters, higher alcohol ether sulfonic acids, alkylolated sulfuric esters of higher fatty acid amides, alkylbenzenesulfonic acids, alkylphenolsulfonic acids, alkylnaphthalenesulfonic acids, and alkylbenzimidazole sulfonic acids. Among these, higher fatty acids, particularly saturated or unsaturated higher fatty acids having 10 to 20 carbon atoms, are particularly preferred.
More specifically, saturated fatty acids such as capric acid, undecanoic acid, lauric acid, myristic acid, palmitic acid, margaric acid, stearic acid, and arachic acid, lindelic acid, tuzunic acid, petroselic acid, oleic acid, linoleic acid, and linolenic acid. Examples include acids, unsaturated fatty acids such as arachidonic acid, and mixtures thereof, with saturated fatty acids being particularly preferred. Specific examples of surfactants include anionic surfactants and nonionic surfactants. The former include primary higher fatty acid salts, secondary higher fatty acid salts, primary higher alcohol sulfate ester salts, and Secondary higher alcohol sulfate ester salt, primary higher alkyl sulfonate, secondary higher alkyl sulfonate, higher alkyl disulfonate, sulfonated higher fatty acid salt, higher fatty acid ester sulfonate, sulfuric acid of higher alcohol ether Ester salts, sulfonates of higher alcohol ethers, alkylol sulfate ester salts of higher fatty acid amides, alkylbenzene sulfonates, alkylphenolsulfonates, alkylnaphthalene sulfonates, alkylbenzimidazole sulfonates, etc., the latter being alkyl ethers. , alkyl allyl ether,
Alkyl thioether, alkyl ester, sorbitan monoalkyl ester, polyoxyethylene alkylamine, polyoxyethylene alkyl amide, polyoxyethylene polyoxypropylene, pentaerythritol ester,
Examples include sugar rose ester, fatty acid ethanolamide, methicolamide, oxymethylethanolamide, and the like. Of course, anionic and nonionic surfactants other than those exemplified, as well as cationic surfactants and amphoteric ionic surfactants not exemplified here, may be used.More detailed examples of these surfactants can be found, for example, in Hiroshi Horiguchi. It is disclosed in "Synthetic Surfactants" (1963, Sankyo Publishing). Among the above surfactants, when one converted into an anionic surfactant by addition treatment with a basic substance is used, the produced ultrafine fiber bundle exhibits properties on the alkaline side, that is, PH9 or higher. In addition, nonionic surfactants produce ultrafine fiber bundles that exhibit approximately neutral pH. In the case of nonionic surfactants,
Those with an HLB value of 13 to 19 are preferable because they result in ultrafine fibers with a smaller diameter. HLB value is Griffin
It is derived from the formula, and details can be found in the Surfactant Handbook (written by Nishiichiro et al., Sangyo Tosho, 1962).
It is disclosed on pages 307-310. (D) Organic Solvent Organic solvents have a high molecular weight or narrow molecular weight distribution, high melt viscosity, and are used when making ultrafine fiber bundles from thermoplastic resins that are difficult to melt and knead. Therefore, melt fluorate (MFR, ASTV D
1238) is less than 1 g/10 min, the effect is remarkable, but of course it can also be applied to resins with low melt 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, if necessary, C. Examples of such organic solvents include aromatic hydrocarbons such as benzene, toluene, xylene, styrene, α-methylstyrene, and vinylbenzene;
Examples include aliphatic hydrocarbons such as hexane and heptane, and halogenated hydrocarbons such as trichloroethylene. (E) Others In addition to those listed above, petroleum resins,
A and/or rosin and asphalt.
Or B may be used in combination with C and D if necessary, and it is particularly preferable to combine it with the water-swellable or water-soluble resin of A. <Preferred embodiment of auxiliary agent> There are various ways to use the auxiliary agent, for example, using 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/
Alternatively, a combination of B, C, and D, or a combination of A and E, etc. can be mentioned. More preferably, a neutralized or saponified modified resin (B) is used when the fiber diameter is made relatively thick (approximately 50μ or more), or a neutralized or saponified modified resin is used when the fiber diameter is made thin (approximately less than 50μ). (B) and a surfactant (C), or when aiming for neutral ultrafine fibers, select a nonionic surfactant as (C) from the above combination, or When aiming for ultra-fine fibers, neutralized or saponified modified resin (B), surfactant (C) and organic solvent are used.
(D) is used, and furthermore, when the fiber bundle itself is to be firmly solidified, a water-soluble resin (A) is used. The amount of the auxiliary agent used varies depending on the type of thermoplastic resin to be made into ultrafine fiber bundles and the type of auxiliary agent, but it is generally 75 to 98 parts by weight of the thermoplastic resin, particularly 80 to 95 parts by weight of the auxiliary agent. 2 to 25 parts by weight, especially 5
~20 parts by weight (however, the total of both is 100 parts by weight). In particular, as a preferred embodiment of the present invention, when using a thermoplastic resin, a neutralized or saponified modified resin, and a surfactant, 75 to 98 parts by weight, 1 to 20 parts by weight, and 1 to 5 parts by weight each (the total is 100 parts by weight), particularly in proportions of 80 to 95 parts by weight, 3 to 16 parts by weight, and 2 to 4 parts by weight. Furthermore, in the case where a water-swellable or water-soluble thermoplastic resin is used in place of the surfactant in this combination, the ratio may be approximately the same as above. <Addition of water> The amount of water added to the system consisting of the thermoplastic resin and the auxiliary agent is 3 to 20 parts by weight, particularly 5 to 15 parts by weight, based on the total of 100 parts by weight of the thermoplastic resin and the auxiliary agent. be. When the amount of water is within this range, the desired thermoplastic resin can be formed into ultrafine fiber bundles. Water can be added in various ways, including a method in which it is added in advance together with the thermoplastic resin and an auxiliary agent before melt-kneading, and a method in which water is gradually added during melt-kneading. Moreover, the water to be added is not only added as pure water, but also, for example, when a surfactant is used as an auxiliary agent, there is a method of adding it as an aqueous solution and adding the surfactant and water together. <Manufacture of ultrafine fiber bundle> To manufacture the ultrafine fiber bundle, the thermoplastic resin, auxiliary agent, and water are melt-kneaded and then spun from an orifice such as a spinning nozzle.
It can be produced by spinning fibers in which a large number of ultrafine fibers with a diameter of 200 μm or less are bundled in a substantially parallel state through a single orifice hole. The following points should be noted at this time. Initially, the melt-kneaded product is in a form in which water is dispersed in the thermoplastic resin (W/O type), but as the melt-kneading continues, water becomes a continuous phase due to the action of the auxiliary agent. The thermoplastic resin is dispersed inside (O/W type). When spinning from an orifice, use the above W/O type to O/W type.
This is done just before the phase inversion occurs in the mold. Spinning is performed by passing the fiber through an orifice. Spinning under conditions where water does not substantially flash. To explain the meaning of the above in detail, the water added to the system is gradually sucked into the molten resin by the shearing force caused by kneading and the action of the auxiliary agent, forming a W/O type dispersion. If the shearing force continues to be applied, the amount of water dispersed will be small (at most 3 to 3 parts per 100 parts by weight of the thermoplastic resin and auxiliary).
20 parts by weight), water becomes a continuous phase and undergoes a phase inversion to an O/W type. From this W/O to O/
On the verge of the phase transition of W, water does not become a complete continuous phase (water combined three-dimensionally), but continues in a certain direction (water combined two-dimensionally).
It is thought that this is the case. Therefore, under the latter condition, the thermoplastic resin is considered to be not particles but a fibrous resin phase that is continuously connected in one direction. By spinning under such conditions, the fiber bundle of the present invention can be spun, and W/
Even if O-type or completely O/W-type fibers are spun, it is not only impossible to produce an ultrafine fiber bundle as in the present invention, but there are also cases where the fibers are not even in the form of fibers. Therefore, the term "just before phase inversion" as used herein refers to the range in which fiber bundles such as those of the present invention can be spun. The meaning of spinning by passing through an orifice is that, as mentioned above, the resin on the verge of phase inversion becomes fibrous with water as the boundary phase. Since it is a type of resin, it has the effect of aligning the fibrous resin by aligning it in a certain direction. What is different from the conventional melt spinning method is that no matter what the shape of the orifice, the melt-kneaded material that passes through the orifice is produced by a large number of microfibers (with a diameter of 200 μm or less) from one orifice hole. The fibers come out as bundles of fibers that are bundled approximately parallel to the direction in which they are extruded. About When the melt-kneaded material is finally spun to the outside,
Conditions under which the contained water does not substantially flash, ie, rapid extrusion so as to cause water to flash as in the conventional flash spinning method, should be avoided. If the melt-kneaded material is rapidly extruded as in the flash spinning method or extruded with differential pressure applied, fiber bundles cannot be obtained. More specifically, there is a method in which spinning is performed under pressure, or a method in which the pressure in a melt kneading machine is made approximately the same as atmospheric pressure and spinning is performed under atmospheric pressure. The moisture content of the fiber bundle obtained by spinning under such conditions is 17% by weight or less. As a specific device for producing the ultrafine fiber bundle of the present invention, there is, for example, a method of extruding it using a single-screw or twin-screw extruder. In the case of a twin-screw extruder, the shear force is too strong and it is difficult to reproduce the state on the verge of phase inversion.
It is better to weaken the shearing force by making the screw groove a special shape. Generally, a single-screw extruder is preferred because it has a weak shearing force and can easily reproduce a state on the verge of phase inversion.
The shape of the orifice may be a typical spinneret or a T-die used in film forming. <Properties of the ultrafine fiber bundle> The properties of the ultrafine fiber bundle produced by the method described above are substantially the same as single fibers molded alone, with a substantially circular cross-sectional shape and a substantially indefinite length. diameter
It is an ultrafine fiber bundle in which a large number of thermoplastic resin ultrafine fibers of 200μ or less, often 100μ or less, are bundled in a substantially parallel state without being twisted, and the ultrafine fibers that make up the fiber bundle are partially twisted. It means that there is a place where it is bonded. Therefore, when this fiber bundle is unraveled, it appears to be fibrous at first glance because of the adhesive parts. More specifically, photographs showing the fiber shape of an example of the ultrafine fiber bundle of the present invention are shown in FIGS. 1 to 4. FIG. 1 is a photograph (2x magnification) showing the fiber bundle of the present invention, and it can be seen that there is no twist at all. FIG. 2 (5x magnification) and FIG. 3 (5x magnification) are photographs showing the fiber bundle in an unraveled state, and it can be seen that the fiber bundle is made up of a large number of ultra-fine fibers bundled approximately in parallel. Figure 4 is a partially enlarged photograph (40x magnification) of the separated fiber bundle, and it can be seen that the ultrafine fibers are partially adhered to each other. The fact that the fibers constituting the fiber bundle of the present invention are substantially equivalent to single fibers molded singly means that each constituent fiber can be The shape is substantially the same as when molded individually (for example, by melt-spinning molding), and although the thickness of each fiber is not necessarily the same, there is no substantial branching other than due to adhesion between fibers. The fiber bundle of the present invention is composed of these fibers. Therefore, the shape is different from physically splitting a melt-molded belt-like or string-like molded product, and there is no cut surface on the surface of each fiber, and there is substantially no fuzz. [Example] The present invention will be explained below using preferred examples.
The content of the present invention is not limited to these examples unless otherwise specified. Example 1 A single-screw extruder with a pent (manufactured by Thermoplastics, diameter 30φL/D=
36) low density polyethylene (manufactured by Mitsui Petrochemical Industries, Ltd., product name Mirason FL−)
60 MFR = 70g/10min Density = 0.915g/cm ³ Sp value = 7.80 (Cal/cm ³ ) ^1/2 ) 93 parts by weight and maleic anhydride grafted polyethylene (maleic anhydride content 3.3
weight%, Group = 0.67 mmol equivalent/g, Mw = 2700 Density = 0.94
g/cm ³ , Sp value 8.06 (Cal/cm ³ ) ^1/2 ) 5 parts by weight of the mixture was continuously supplied at a rate of 98 parts by weight/hour.
Plasticize at °C. Next, an anionic surfactant (manufactured by Kao Soap Co., Ltd., trade name Emulgen 430 polyoxyethylene oleyl ether HLB = 16.2) was poured into the liquid inlet provided in the first metering zone of the same extruder.
Pressurize a 16.7% aqueous solution of
Continuously supplied at a rate of 12 parts by weight/hour (pressure
120Kg/cm ² G) After passing through a 100 mesh screen at an extrusion temperature of 95°C, it was continuously extruded from a nozzle with a diameter of 3mm. The product was a white fiber bundle in which single fibers were bundled in a substantially parallel state, and the moisture content was measured to be 9%. Next, when the fiber bundle was spread out and the single fibers were observed under a microscope, it was found that there were some parts where the single fibers were adhered to each other. The thickness of single fiber is approximately 25 to 50μ
It was within the range of Examples 2 to 9 The composition ratios shown in Table 1 were the same as in Example 1.
The results are shown in Table 1.

【table】

[Table] Example 10 From the hopper of the same extruder used in Example 1, low-density polyethylene (manufactured by Mitsui Petrochemical Industries, Ltd., trade name Mirason FL-60MFR = 70 g/
10min density = 0.915g/cm ³ Sp value = 7.80 (Cal/cm ³ ) ^1/2 )
and maleic anhydride grafted polyethylene (maleic anhydride content 3.3% by weight, Group = 0.67 mmol equivalent/g, Mw = 2700, density =
A mixture of 0.94 g/cm ³ , Sp value 8.06 (Cal/cm ³ ) ^1/2 ) and 92/5/3 (weight ratio) of stearic acid was continuously supplied at a rate of 100 parts by weight/hour at 140°C. to plasticize it. Next, 9.8% potassium hydroxide aqueous solution was pressurized with a plunger pump and continuously supplied at a rate of 8 parts by weight/hour from the liquid inlet provided in the first measuring zone of the extruder (pressure 120 kg/hour). cm ² G) Extrusion was carried out in the same manner as in Example 1 at an extrusion temperature of 95°C. The product was a white fiber bundle in which single fibers were bundled in a substantially parallel state, and the moisture content was measured to be 7%. Next, when the fiber bundle was spread out and the thickness of the single fibers was examined, it was found to be approximately within the range of 25 to 50μ. Further, 5 parts by weight of fiber bundles were added to 100 parts by weight of water, and the pH of the water layer was measured and found to be 10.5. Examples 11 to 16 The composition ratios shown in Table 1 were the same as in Example 10.
The results are shown in Table 2.

【table】

[Reference example]

Ethylene/acrylic acid copolymer resin (AC polyethylene 5120 manufactured by Allied Chemical Co., Ltd., acrylic acid content 15% by weight, Group = 2.14 mmol equivalent/g, viscosity (140°C) =
650cps, density = 0.93g/cm ³ , Sp value = 8.58 (Cal/
cm ³ ) ^1/2 ) 30 parts, 66 parts water and 3.60 parts potassium hydroxide ( 1.0 chemical equivalent (based on the base) into an autoclave equipped with a stirrer, and heated and stirred at 140°C for 1 hour (parts by weight). Next, when the cooled contents of the autoclave were taken out, a white jelly-like emulsion was obtained. The particle size of the emulsion is less than 0.5μ and is neutralized. The group was 2.1 mmol equivalent/g. Example 18 Ethylene-propylene copolymer resin (ethylene content
80mol%, MFR=1.1g/10min, density=0.88g/
cm ³ , Sp value = 7.87 (Cal/cm ³ ) ^1/2 ) and 75 parts by weight of a 92/5/3 (weight ratio) mixture of the same maleic anhydride grafted polyethylene and stearic acid used in Example 1. / hour continuously, 120
Plasticize at °C. Next, ethylene tetrachloride was added at a rate of 25 parts by weight/hour from the liquid injection port provided in the first compression zone of the same extruder, and 4% potassium hydroxide was added from the liquid injection port provided in the first metering zone. Example 1: The aqueous solution was continuously supplied at a rate of 15 parts by weight/hour using a plunger pump, and the heating temperature was 80°C.
It was extruded in the same way. The product is a white fiber bundle, and the single fiber diameter is approximately
It was in the range of 55 to 110μ. Example 19 From the hopper of the same extruder used in Example 1, ethylene/vinyl acetate copolymer resin (vinyl acetate content 19% by weight, MFR = 150 g/10 min, density = 0.97)
g/cm ³ , Sp value = 8.06 (cal/cm ³ ) ^1/2 ), 98 parts by weight/
Continuously feed at the rate of time and plasticize at 120℃. Next, 20 parts by weight of a 10% aqueous solution of polyvinyl alcohol (product name: Gohsenol KH-17 manufactured by Nippon Gosei Kagaku Kogyo Co., Ltd., saponification degree 80%) was poured into the liquid inlet provided in the first metering zone of the same extruder, and the plunger Continuously supplied by pressurizing with a pump (pressure 80Kg/
cm ² G), extrusion was carried out in the same manner as in Example 1 at an extrusion temperature of 90°C. The product was a white fiber bundle with a moisture content of 13%. Next, when we expanded the fiber bundle and observed it, we found that
The single fibers were arranged in a substantially parallel state, some of which were partially adhered, and the thickness of the single fibers was approximately in the range of 35 to 70μ. However, when the fiber bundle was left at room temperature until the next day, polyvinyl alcohol formed a film and the fibers could not be opened. Example 20 Instead of the ethylene/vinyl acetate copolymer resin used in Example 19, 90 parts by weight of the low-density polyethylene used in Example 1 and hydrogenated petroleum resin (trade name: Alcon P-100 manufactured by Arakawa Chemical Industries, Ltd.) were used. softening point
At 100°C, a mixture of 10 parts by weight (molecular weight 700) was continuously supplied at a rate of 98 parts by weight/hour, and the extrusion temperature was increased to 95°C.
The same procedure as in Example 19 was carried out except that the temperature was changed to ℃. The fiber thickness of the product was generally within the range of 30-60μ. Example 21 The procedure of Example 20 was repeated except that the hydrogenated petroleum resin in Example 20 was replaced with the maleic anhydride grafted polyethylene used in Example 1. The fiber thickness of the product was generally within the range of 40-80μ.

[Brief explanation of drawings]

FIGS. 1 to 4 are micrographs showing the fiber shape of the present invention.

Claims (1)

[Claims] 1 An ultrafine fiber bundle that is spun from an orifice after melting and kneading a thermoplastic resin, water and an auxiliary agent that assists in dispersing the water into the thermoplastic resin, and is spun from an orifice hole. A large number of ultrafine fibers with a diameter of 200 μm or less with a substantially circular cross-sectional shape and substantially indefinite length, which are substantially equivalent to the single fibers molded in An ultrafine fiber bundle that is characterized by the presence of a portion of fiber that forms a fiber bundle.