JP4099024B2 - Surface porous fiber and fiber sheet manufacturing method, and surface porous fiber and fiber sheet - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fiber and a fiber sheet having a large number of pores only on the surface, a method for producing a surface porous fiber and a fiber sheet, and a surface porous material that can be suitably used for applications such as a wiper or a filter material. The present invention relates to a modified fiber and a fiber sheet.
[0002]
[Prior art]
Examples of the fibers having pores on the surface include, for example, JP-A-5-125667 (Patent Document 1), a fiber main body made of a polypropylene resin having a melt flow rate of 0.5 to 9 g / 10 min, and the polypropylene system. The fiber main body comprises a large number of pores formed by mixing a resin and paraffin wax under melting, melt spinning with an extruder at a draft rate of 400 or less, and drawing and removing the paraffin wax after heat treatment. Specific surface area of 20m² Polypropylene-based porous fibers in which the ratio of the pores to the fiber body is 20% or more and the denier of the fiber body is 50 or less is described. However, in this porous fiber, the lamellar crystals are deformed into zigzags by hot drawing, and the paraffin wax layer formed between these crystals is extracted and removed, so that the pores become wider or narrower in the fiber cross section. While repeating the above, the pores that are connected from the surface to the inside are formed in a form like a pore. As described above, since not only the surface of the fiber but also the inside of the fiber is porous, there is a problem that the strength of the entire fiber is weakened. Moreover, there existed a problem that paraffin wax remained or the extract liquid remained in the inside of a fiber. In addition, in order to prevent the paraffin wax and the extract from remaining, there is a problem in that the production cost increases because it takes too much time and time.
[0003]
JP-A-64-6114 (Patent Document 2) discloses a nylon fiber having a concavo-convex structure on the surface, and the concavo-convex shape has a valley along the outer periphery in a direction perpendicular to the longitudinal direction of the fiber. The distance between the bottom of the valley and the bottom of the valley adjacent to it is about 3 to 30 μm, and the vertical distance between the peak of the mountain and the bottom of the valley is about 0.2 to 2 μm. Synthetic fibers having a concavo-convex structure on the surface, which has a concavo-convex shape in which 0.2 to 3 peaks are present, are described. This synthetic fiber is obtained by a method of cooling a spun single fiber in a warm water bath at 30 ° C. or higher for a predetermined time during melt spinning. This publication also speculates that when semi-molten nylon molecules partially on the surface in warm water are recrystallized or re-agglomerated, small spherical ones are formed and the surface becomes uneven. Has been. Further, it is described that by further stretching the synthetic fiber, the concavo-convex pattern becomes a cocoon-shaped synthetic fiber that is changed into elongated peaks and valleys extending in the stretching direction.
[0004]
In this way, the surface of the synthetic fiber has a shape in which a large number of spherical protrusions are gathered. Therefore, when this fiber is used for, for example, a wiper, a point contact with an object to be wiped is performed. There was a problem that resistance became less. In addition, since the concave portions are not hemispherical pores, it is difficult to retain the wiped dust or liquid, and there is a problem that a sufficient wiping effect cannot be obtained. Further, when this fiber is used for applications such as a filter, it is difficult to retain dust on the fiber surface, and there is a problem that the effect of improving the dust retention ability cannot be obtained sufficiently. In addition, this synthetic fiber has a problem that when a large number of spherical protrusions are provided, the drawing becomes insufficient and the strength of the fiber cannot be increased. On the other hand, when the fiber is stretched to increase the strength of the fiber, the strength of the fiber is increased, but the spherical protrusions are changed into elongated ridges and valleys extending in the stretching direction and become hooked. For this reason, there is a problem that a structure in which a large number of pores are gathered on the fiber surface, that is, a structure having porosity is not formed, and an effect due to the porous structure does not occur.
[0005]
Japanese Patent Application Laid-Open No. 5-15803 (Patent Document 3) discloses artificial hair made of a polyester fiber having a roughened fiber surface, and the fiber has an average fineness X of 30 to 70 denier. Further, the fiber surface has an average pitch of 0.1 to 1.5 μm between the recesses and the adjacent recesses and a density of 5 to 100 irregularities per 10 μm average distance. Has been. This artificial hair is made by mixing inorganic particles having an average particle diameter of 1 μm or less and a refractive index of 1.8 or less at the time of polyester polymer polymerization or spinning, spinning the particle-containing polymer, and drawing the drawn fiber. The total fineness is 10⁴It can be obtained by performing etching by alkali treatment in a state of being converged to be denier or more. The purpose of this artificial hair is to make the gloss and texture of conventional polyester-based artificial hair close to that of natural hair, as well as having excellent light fastness and no color change. In addition, it is described that the fine particles to be added also play an important role in the surface roughening after spinning and the glossy texture after dyeing.
[0006]
Thus, although the surface of this artificial hair has irregularities formed by etching by alkali treatment, no pores are formed, and this irregularity has an effect that affects gloss, Since hemispherical pores are not formed as the recesses, the effect of the porous structure formed by such hemispherical pores was not obtained. For example, when a wiper is made using this fiber, there is no effect of holding the dust or liquid wiped off, and when it is used as a filter, dust is held on the fiber surface and the dust holding ability is improved. The improvement effect was not obtained.
[0007]
Prior art document information related to the invention of this application includes the following.
[Patent Document 1]
JP-A-5-125667
[Patent Document 2]
Japanese Patent Application Laid-Open No. 64-6114
[Patent Document 3]
Japanese Patent Laid-Open No. 5-15803
[0008]
[Problems to be solved by the invention]
The present invention is intended to solve the problems of the prior art over such prior art, and the fiber surface is made of hemispherical pores while maintaining the physical properties such as fiber strength inherent to the fiber. A method for producing a surface porous fiber and a fiber sheet, which has excellent functions such as a wiping effect, dust and liquid retention effect, or dye fixing effect, and the surface porous fiber. It is another object of the present invention to provide a fiber sheet.
[0009]
[Means for Solving the Problems]
Means for solving the above-mentioned problems is a method for producing a fiber having pores on at least a surface of a fiber mainly composed of a thermoplastic resin, wherein the fiber is formed on the surface of the fiber. Solid particles having a melting point or decomposition temperature higher than the melting point of the thermoplastic resin are fixed by surface fusion to form solid particle fixed fibers, and thereafter the solid particles of the solid particle fixed fibers are removed. It is a manufacturing method of the surface porous fiber made into.
[0010]
In the invention of claim 2, the method of fixing the solid particles to the fiber surface by fusing the fiber surface heats the solid particles to a temperature equal to or higher than the melting point of the thermoplastic resin, It is a manufacturing method of the surface porous fiber of Claim 1 which is a method of making a heating solid particle contact with the said fiber and maintaining it in the state maintained at the temperature more than melting | fusing point.
[0011]
The invention of claim 3 is a method of using water-soluble solid particles for the solid particles and a method of removing solid particles of the solid particle-fixed fibers by dissolving them in water. It is a manufacturing method of surface porous fiber.
[0012]
The invention according to claim 4 is a method for producing a fiber sheet having pores on the fiber surface of the fiber sheet containing fibers mainly comprising a thermoplastic resin at least on the surface, wherein the fiber surface comprises Solid particles having a melting point or decomposition temperature higher than the melting point of the thermoplastic resin are fixed by fusion to form solid particle fixed fibers, and then the solid particles of the solid particle fixed fibers are removed. It is a manufacturing method of a surface porous fiber sheet.
[0013]
In the invention of claim 5, the method of adhering the solid particles to the fiber surface by fusing the fiber surface heats the solid particles to a temperature equal to or higher than the melting point of the thermoplastic resin, It is a manufacturing method of the surface porous fiber sheet of Claim 4 which is the method of making a heating solid particle contact with the said fiber sheet, and making it adhere in the state maintained at high temperature more than melting | fusing point.
[0014]
The invention of claim 6 is a method of using water-soluble solid particles as the solid particles, and a method of removing solid particles of the solid particle fixed fibers by dissolving them in water. It is a manufacturing method of a surface porous fiber sheet.
[0015]
  The invention according to claim 7 is a surface-perforated fiber in which pores are formed only on the surface of a fiber whose surface is mainly made of a thermoplastic resin, and the pores are melted on the surface of the fiber. Porous surface produced by removing solid particles fixed by the fiber from the surface of the fiberIt is.
[0016]
  Claim8In the invention, the shape of the opening of the pore is substantially circular or substantially polygonal, and the average diameter of the opening is 0.1 to 10 μm.7It is the surface porous fiber of description.
[0017]
  Claim9In the invention, the average depth of the pores is 0.1 to 10 μm.Or 8The surface porous fiber described in 1.
[0018]
  Claim10In the invention, the number of the pores is 100 μm on the fiber surface.²It is 10-1000 per one, Claims 7-9The surface porous fiber according to any one of the above.
[0020]
  Claim11In the invention of claim 7,10It is a surface porous fiber sheet containing the surface porous fiber in any one of.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
[1] Method for producing surface porous fiber or surface porous fiber sheet according to the present invention
According to the method for producing a surface porous fiber according to the present invention, it is possible to produce a fiber having pores on the surface of a fiber whose surface is mainly composed of a thermoplastic resin. In the method for producing a surface porous fiber according to the present invention, solid particles having a melting point or decomposition temperature higher than the melting point of the thermoplastic resin are fixed to the fiber surface by fusing the fiber surface, thereby fixing the solid particle fixing fiber. After that, the solid particles of the solid particle fixing fiber are removed.
[0022]
According to the method for producing a surface porous fiber sheet according to the present invention, it is possible to produce a fiber sheet having pores on the surface of the fiber sheet including at least a fiber whose surface is mainly composed of a thermoplastic resin. it can. In the method for producing a surface-porous fiber sheet of the present invention, solid particles having a melting point or decomposition temperature higher than the melting point of the thermoplastic resin are fixed to the fiber surface by fusing the fiber surface to fix the solid particles. The fibers are formed, and then the solid particles of the solid particle fixed fibers are removed.
[0023]
The fiber used in the method for producing a surface porous fiber according to the present invention or the fiber contained in the fiber sheet used in the method for producing a surface porous fiber sheet according to the present invention is a fiber whose surface is mainly composed of a thermoplastic resin. Yes, as long as the fiber surface melts by heating (for example, heating at 50 ° C. or higher, preferably heating at 80 ° C. or higher), the type of the fiber can be selected as appropriate. Examples of such fibers include synthetic fibers obtained by melt spinning, which is a conventional fiber production method, fibers obtained by a spunbond method, melt blow method, flash spinning method, etc., which are conventional nonwoven fabric production methods, or core portions. It can be appropriately selected from natural fibers or fibers made of inorganic fibers.
[0024]
As said fiber obtained by the manufacturing method of the said synthetic fiber or a nonwoven fabric, the synthetic fiber which consists of thermoplastic resins (for example, polyolefin fiber, polyester fiber, or polyamide fiber etc.) can be mentioned, for example, The said synthetic fiber is 1 Even if it is a synthetic fiber made of a kind of thermoplastic resin or a composite fiber in which two or more different kinds of resins are composited, it can be appropriately selected and used. Examples of such composite fibers include composite fibers in which two or more kinds of resins having different melting points are combined, such as copolymer polyester / polyester, copolymer polypropylene / polypropylene, polypropylene / polyamide, polyethylene / polypropylene, Mention may be made of composite fibers made of a combination of resins such as polypropylene / polyester or polyethylene / polyester. In addition, when the composite fiber is a core-sheath type composite fiber having a high melting point resin in the core and a low melting point resin in the sheath, when the solid particles are fixed to the fiber surface, the fiber contraction or yarn This is preferable because breakage is less likely to occur.
[0025]
In addition, the fiber is preferably a fiber whose entire fiber is substantially made of only a fiber-forming resin, but a fiber having a decomposition temperature without having a melting point at its core, for example, rayon fiber, It can also be a fiber in which a thermoplastic resin is applied as a sheath portion to the surface of a fiber such as acetate fiber, wool fiber, or carbon fiber, for example, by coating. Moreover, the thermoplastic resin is used as a sheath part on the surface of a fiber such as a fiber having a high melting point, for example, a glass fiber, a ceramic fiber, or a metal fiber, the core part of which is an inorganic fiber. It can also be a fiber applied by coating or the like.
[0026]
Examples of the fiber mainly comprising at least a surface of a thermoplastic resin include, for example, a fiber having at least a surface made of one or more thermoplastic resins, a fiber having at least a surface substantially made of one or more thermoplastic resins, or Mention may be made of fibers mainly comprising at least one or more thermoplastic resins, at least one surface comprising fibers comprising one or more thermoplastic resins, or at least one surface comprising one or more thermoplastic resins. Substantially fibers are preferred. In this specification, “consisting mainly of” means that the area occupied by the target thermoplastic resin on the fiber surface is 50% or more (preferably 60% or more, more preferably 70% or more) with respect to the surface area of the fiber. It is particularly preferably 90% or more. Moreover, the cross-sectional shape or surface shape of the fiber can be any shape. For example, a composite fiber made of a thermoplastic resin can be a fiber having a chrysanthemum-like cross-sectional shape divided by mechanical stress such as water flow, or a fiber divided into fibrils.
[0027]
The average diameter and length of the fibers are, for example, synthetic fibers obtained by melt spinning, which is a conventional fiber production method, fibers obtained by a spunbond method, melt blow method, flash spinning method, etc., which are conventional nonwoven fabric production methods, or A fiber having an average diameter and length of a fiber such as a fiber having a core part made of natural fiber or inorganic fiber can be appropriately selected. For example, the average diameter of the fibers can be a wide range of average diameters ranging from 0.1 μm to 3 mm. The average diameter of the fibers is preferably in the range of 0.1 μm to 500 μm, more preferably in the range of 0.1 μm to 100 μm. Here, when the cross-sectional shape of the fiber is other than a circle, the average diameter of the fiber is the diameter of a circle having the same area as the cross-sectional area of the fiber, and the number average fiber diameter by sampling from any 500 or more positions of the fiber And
[0028]
In addition, when it is difficult to measure the cross-sectional area of the fiber, the side surface of the fiber is enlarged and photographed with a scanning electron microscope or the like. The number average fiber diameter obtained by sampling can be the fiber diameter of the fiber.
Further, in the case of commercially available fibers, when the number average fiber diameter is clearly shown in catalogs or specifications, the value may be used as the average fiber diameter. Further, when the fiber diameter is clearly specified in the unit of denier or decitex in the catalog or specification, the value may be converted into the unit of length to obtain the average fiber diameter.
[0029]
The fiber sheet used in the method for producing a surface porous fiber sheet of the present invention is particularly limited as long as the fiber sheet has the above-described fibers, that is, fiber sheets having at least a surface mainly composed of a thermoplastic resin. Instead, the fiber sheet can include only the fibers or can include fibers other than the fibers. The fibers other than the above-described fibers (that is, fibers having at least the surface mainly composed of thermoplastic resin) are not particularly limited, and the surface is not a thermoplastic resin, such as inorganic fibers, or has no melting point, and has a decomposition temperature. The fiber which has can be used.
[0030]
Examples of the structure of the fiber sheet include a woven fabric, a knitted fabric, a non-woven fabric, or a combination thereof. In the case of a woven fabric or a knitted fabric, it can be obtained, for example, by processing the fibers with a loom or a knitting machine. Moreover, in the case of a nonwoven fabric, it can be made into a fiber sheet by, for example, a conventional nonwoven fabric manufacturing method such as a dry method, a spunbond method, a melt blow method, a flash spinning method, or a wet method. In addition, the fiber web formed by these manufacturing methods is premixed with adhesive fibers and / or composite fibers in which two or more types of resins having different melting points are combined, and then the heat treatment is performed. It can be a bonded fiber sheet. Moreover, it can also be set as the fiber sheet which entangled between the said fiber webs by a mechanical entanglement process (for example, water flow entanglement or a needle punch). Alternatively, the fiber web may be passed between a heated smooth roll and a heated uneven roll to form a partially bonded fiber sheet. Moreover, it can also be set as the fiber sheet formed by laminating | stacking the said fiber sheet from which a kind differs, and further integrating.
[0031]
Further, the shape of the fiber sheet is not particularly limited, and for example, a long fiber sheet (for example, a fiber sheet wound around a roll) or a non-long fiber sheet (that is, the long fiber sheet). And the like can be obtained by cutting the fiber sheet).
[0032]
The solid particles used in the method for producing a surface porous fiber or the method for producing a surface porous fiber sheet according to the present invention has a melting point higher than the melting point of the thermoplastic resin constituting the surface of the fiber used for fixing the solid particles, or As long as it is a solid particle having a decomposition temperature, and as long as the solid particle can be removed after fixing the solid particle to the fiber surface, it can be either inorganic or organic, If it is a particle-like particle | grain, 1 or more types of such a particle | grain can be selected suitably. As such solid particles from which solid particles can be removed, for example, a solvent that does not substantially dissolve the thermoplastic resin that constitutes the surface of the fiber used to fix the solid particles (for example, water, There are solid particles (for example, water-soluble inorganic substances, metal salts, water-soluble resins, metals, etc.) that dissolve in aqueous solutions, acids, alkaline aqueous solutions, and the like. With such solid particles, the solid particles can be easily removed by extraction using the solvent after fixing the solid particles on the fiber surface. Further, for example, in addition to extraction, solid particles that can be removed by vibration, ultrasonic cleaning, fiber shrinkage, fiber surface peelability improving processing, and the like can be given. Examples of the solid particles used in the production method of the present invention include various kinds of materials such as sodium chloride, calcium chloride, calcium carbonate, various other metal salts, water-soluble resins, metal particles, ceramics, zeolite, and other various inorganic substances. It can be a material.
[0033]
The melting point or decomposition temperature of the solid particles needs to be higher than the melting point of the resin having the lowest melting point among the resins constituting the fiber surface, and the melting point or decomposition temperature of the solid particles is the melting point of the resin. When it is lower, the fiber surface is not melted by the heat of the heated solid particles, and the solid particles are not fixed to the fiber surface. That is, even if solid particles are not fixed to the fiber surface, or even if the solid particles are fixed to the fiber surface, the form is such that the solid particles melt before the fiber surface and the solid particles become aggregates, The solid particles and the fiber surface are fused in a wide area. Therefore, the pores cannot be sufficiently formed even after the solid particles are removed.
[0034]
The average particle diameter of the solid particles is preferably equal to or less than the fiber diameter. If the average particle diameter of the solid particles exceeds the fiber diameter, the solid particles may become too large with respect to the fiber surface, and it may be difficult to form porosity on the fiber surface. Moreover, 0.1-10 micrometers is preferable and, as for the average particle diameter of a solid particle, 0.1-5 micrometers is more preferable.
[0035]
In addition, the average particle diameter of solid particles shall represent the number average particle diameter of solid particles. In addition, as a method for calculating the number average particle diameter, the particles are enlarged and photographed with a scanning electron microscope or the like, and the particle diameters of arbitrary 500 or more particles are measured and calculated by dividing by the measured number. . At this time, if the particles are not spherical, the diameter of the circumscribed circle of each particle that can be confirmed in the image of the photographed particle is taken as the particle diameter of each particle.
In the case of commercially available particles, when the number average particle size is clearly shown in catalogs or specifications, the value may be used as the average particle size of the solid particles.
[0036]
In the method for producing a surface porous fiber or the surface porous fiber sheet according to the present invention, solid particles are fixed to the fiber surface by fusing the fiber surface to form solid particle fixed fibers. As a method of fixing solid particles by fusing the fiber surface, for example, solid particles having a melting point or decomposition temperature higher than the melting point of the thermoplastic resin are heated to a temperature equal to or higher than the melting point of the thermoplastic resin (however, The solid particles are heated at a temperature lower than the melting point or decomposition temperature of the solid particles and maintained at a temperature equal to or higher than the melting point of the thermoplastic resin. There is a method in which a fiber sheet is brought into contact and fixed by fusion of the fiber surface. In addition, for example, solid fibers having a melting point or decomposition temperature higher than the melting point of the thermoplastic resin in a state where the fiber surface is heated to a temperature higher than the melting point of the thermoplastic resin and maintained at that temperature. There is a method in which solid particles are fixed by contact with the fiber or fiber sheet and fusion of the fiber surface. Comparing these two methods, the former method, in which the solid particles are heated to a temperature equal to or higher than the melting point of the thermoplastic resin and brought into contact with the fiber or fiber sheet, is more preferable.
[0037]
That is, according to the former method, by bringing the heated solid particles into contact with the fiber surface, only the portion where the solid particles are in contact with the fiber surface is melted to fix the solid particles. Therefore, the solid resin is not substantially buried by melting and fluidizing the entire resin on the fiber surface. In some cases, it is possible to fix a single layer or a single layer composed of a layer having a thickness substantially equal to one solid particle. Such single-layer fixation can be illustrated in a photograph taken with a scanning electron microscope in FIG.
[0038]
Therefore, the solid particles fixed in this manner are then removed, so that uniform pores corresponding to one layer or a single layer made of a layer substantially having a thickness of one solid particle are formed on the fiber surface. Can be formed. Further, for example, as shown in FIGS. 4A and 4B, clear semispherical pores 101 can be formed on the surface 102 of the fiber 100. Here, the semispherical shape includes a substantially hemispherical shape, a substantially elliptical sphere or a polyhedral shape, and a substantially semispherical shape, a substantially elliptical sphere or a shape having irregularities on the surface forming the polyhedron. Shall be included. Further, a depression formed when solid particles in which 10% to 90%, preferably 30% to 70% of the volume of the solid particles are fixed to the surface of the fiber come off from the surface of the fiber. It also includes the shape of the pores. Such hemispherical pores can be illustrated in a photograph taken with a scanning electron microscope in FIG. Further, according to the former method, since the solid particles melt only the fiber surface, even if the fiber is a fiber made of a single resin component, the fiber shrinks during the contact treatment or the fixing treatment, or the entire fiber Melts and breaks the thread, which does not cause a problem.
[0039]
When solid particles are fixed by fusing the fiber surface, the method of bringing the solid particles into contact with the fiber surface is not particularly limited as long as the solid particles can be fixed to the fiber surface. ,
(1) A method of blowing an air stream containing solid particles on the surface of a fiber or fiber sheet;
(2) A method of allowing solid particles to spontaneously fall on a fiber or fiber sheet;
(3) A method of shaking a heat-resistant container charged with solid particles and fibers or fiber sheets;
(4) A method of immersing fibers or fiber sheets in solid particles; or
(5) A method of exposing fibers or fiber sheets in a fluidized bed of solid particles,
And so on. In addition, in the method of (1) to (5) described above, when the solid particles are heated to a temperature higher than that of the thermoplastic resin of the thermoplastic resin and are brought into contact with the fiber or the fiber sheet, Heated solid particles may be applied as the solid particles.
[0040]
For example, in the method (1), a method in which heated solid particles are applied as solid particles is a method (1 ′) in which an air stream containing heated solid particles is blown onto the surface of a fiber or fiber sheet. In the case of this method, the heated solid particle-containing air stream is a mixture in which an air stream is mixed with solid particles heated above the melting point of the thermoplastic resin having the lowest melting point among the thermoplastic resins constituting the fiber surface. Use airflow.
[0041]
To adjust such a mixed airflow, for example,
(A) A method of supplying solid particles heated to a melting point or higher of a thermoplastic resin in an air flow;
(B) a method of supplying solid particles in an air current heated to a temperature equal to or higher than the melting point of the thermoplastic resin; or
(C) A method in which solid particles are supplied in an air stream and heated above the melting point of the thermoplastic resin.
And so on. Among these, according to the mixed airflow adjusting method (b) or (c), the solid particles are heated to a temperature higher than the melting point of the thermoplastic resin through an airflow heated to a temperature higher than the melting point of the thermoplastic resin.
[0042]
In the method of spraying the air flow containing (1 ′) heated solid particles on the surface of the fiber or fiber sheet, for example, the apparatus illustrated in FIG. 1 can be used. FIG. 1 is a schematic view schematically showing one embodiment of an apparatus used in the method for producing a surface porous fiber or surface porous fiber sheet of the present invention. In FIG. 1, the particle mixing means 30 for mixing the solid particles 29 and the airflow A is an ejector, and the airflow A generated in the blower 11 and the heating tube 12 as the airflow generation means is sent to the particle mixing means 30, The mixing means 30 is connected to a funnel-shaped supply container 21 as a particle supply means, a rotary supply control rotor 22 and a supply pipe 23, and is supplied from the particle supply means 21 by the suction force generated by the airflow A. The solid particles 29 to be sucked are supplied, and the solid particles 29 are supplied into the airflow A. The mixed airflow thus obtained (that is, the mixed airflow containing solid particles heated above the melting point of the thermoplastic resin having the lowest melting point among the thermoplastic resins constituting the fiber surface) is used as the ejection means. When ejected from the nozzle 41, the solid particles 29 collide with the fiber surface due to inertial force due to the kinetic energy given at the time of ejection. At the tip of the nozzle 41, the fiber 80 or the fiber sheet 80 'is supported by a rotating roll 70 or 70' that is a support means for supporting the fiber 80 or the fiber sheet 80 '. The solid particles 29 are sprayed on the sheet 80 ′. Further, in FIG. 1, by providing particle recovery means 93 of a system that blows away with an air current, excess solid particles that have not adhered to the fiber 80 or the fiber sheet 80 ′ are removed and recovered.
[0043]
When fixing solid particles by fusion of the fiber surface, as a method of bringing the solid particles into contact with the fiber surface, in the methods of (2) to (5), solid particles heated as solid particles were applied, respectively. When any one of the methods (2 ′) to (5 ′) is used, the solid particles are heated in advance and then brought into contact with the fibers or the fibers contained in the fiber sheet by various contact methods.
[0044]
In the contact method (2 ′), that is, the method in which the heated solid particles are naturally dropped onto the fiber or fiber sheet, for example, the fiber or fiber sheet is placed on a heat-resistant conveyor, and then the upper part of the conveyor. For example, by spraying the heated solid particles, for example, the heated solid particles come into contact with the fiber surface, and at the same time, the heated solid particles are held in a state where only the contact point of the thermoplastic resin on the fiber surface is dissolved. To do. Next, it is allowed to stand at room temperature or, if necessary, cooling means is blown from the upper part of the conveyor, for example, cooling air to cool the fiber or fiber sheet and solid particles, and the solid particles are fixed to the fiber surface. Let Next, the solid particles that have not been fixed to the solid particle fixing fiber are removed by a suitable solid particle removing means, for example, a method of tilting the conveyor and dropping it by vibration or blowing it off with an air current.
[0045]
In the contact method (3 ′), that is, a method of shaking a heat-resistant container charged with heated solid particles and fibers or fiber sheets, for example, the fibers or fiber sheets are placed in a heat-resistant container, Furthermore, the heated solid particles are put into a container, the container lid is closed, the entire container is shaken, and the heated solid particles come into contact with the fiber surface. Keep only the contact point in a melted state. Next, the fiber or fiber sheet is taken out from the container quickly, and the fiber or fiber sheet is cooled to fix the solid particles to the fiber surface. Next, the solid particles that are not fixed to the solid particle fixing fibers are removed by a suitable removing means, for example, water washing.
[0046]
In the method for producing a surface porous fiber or the surface porous fiber sheet according to the present invention, solid particles are fixed on the fiber surface to form solid particle fixed fibers, and then solid particles of the solid particle fixed fibers are formed. Remove. The method for removing the solid particles of the solid particle fixed fiber is not particularly limited as long as the solid particles of the solid particle fixed fiber can be removed. For example, the surface of the fiber used to fix the solid particles is used. There is a method in which solid particles that dissolve in a solvent that does not substantially dissolve the thermoplastic resin that is formed are fixed to the fiber surface, and then the solid particles are removed by extraction using the solvent. In this method, for example, water, an aqueous solution, an acid, an alkaline aqueous solution, or the like is used as the solvent, while a water-soluble inorganic substance, a metal salt, a water-soluble resin, a metal, or the like is used as the solid particles. In particular, a method using a metal salt or a water-soluble resin as the solid particles while using water as the solvent is preferable because the production cost is low. Examples of such metal salts include sodium chloride, calcium chloride, ammonium chloride, sodium bicarbonate, potassium bicarbonate, and the like. Examples of such water-soluble resins include polyvinyl alcohol, polyethylene glycol, and polyacrylic acid.
[0047]
Further, as another method for removing the solid particles of the solid particle fixed fiber, for example, there is a method in which the solid particle fixed fiber is vibrated to separate the solid particle from the fiber surface. In addition, there is a method in which solid particles are separated from the fiber surface by ultrasonic cleaning. In addition, there is a method in which the solid particles are separated from the fiber surface by stretching or shrinking the fibers of the solid particle fixed fibers. Also, there is a method in which the surface of the fiber is preliminarily processed to improve the releasability of the fiber surface by, for example, water-repellent processing or oil-repellent processing, and then solid particles are fixed and the solid particles are peeled off from the fiber surface is there.
[0048]
In addition, in the manufacturing method of the surface porous fiber sheet, in addition to the above method, that is, other than the method of using the fiber contained in the fiber sheet as the surface porous fiber, the surface porous fiber is formed in advance, A method of forming a sheet using a fiber including the surface porous fiber is also possible.
[0049]
According to the production method of the present invention (including both the production method of the surface porous fiber according to the present invention and the method of production of the surface porous fiber sheet according to the present invention), solid particles are fixed only on the fiber surface, Since the solid particles are removed, only the fiber surface can be reliably made porous by the pores while maintaining the physical properties such as fiber strength inherent to the fiber. In addition, since pores with the required size can be formed according to the shape of the solid particles, the wiping effect, the dust and liquid retention effect, or the dye fixing effect due to the pore formation can be met as required. In addition, it can exhibit excellent functions. Moreover, according to the manufacturing method of this invention, the surface porous fiber sheet containing such surface porous fiber or surface porous fiber can be obtained easily.
[0050]
[2] Surface porous fiber and surface porous fiber sheet of the present invention
In the surface porous fiber of the present invention, pores are formed only on the surface of a fiber whose surface is mainly composed of a thermoplastic resin.
The surface porous fiber of the present invention can be produced, for example, by the method for producing a surface porous fiber according to the present invention.
[0051]
The surface porous fiber of the present invention is a fiber in which pores are formed only on the surface of a fiber whose surface is mainly composed of a thermoplastic resin. With regard to the “fibers mainly composed of thermoplastic resin at least on the surface”, the description regarding “fibers mainly composed of thermoplastic resin at least on the surface” described above in the production method of the present invention is applied as it is. That is, the type of fiber is not limited as long as it is a fiber whose surface is mainly composed of a thermoplastic resin and the fiber surface is melted by heating (for example, heating at 50 ° C. or higher, preferably 80 ° C. or higher). It can be selected appropriately. Examples of such fibers include synthetic fibers obtained by melt spinning, which is a conventional fiber production method, fibers obtained by a spunbond method, melt blow method, flash spinning method, etc., which are conventional nonwoven fabric production methods, or core portions. It can be appropriately selected from fibers made of natural fibers or inorganic fibers.
[0052]
In the surface porous fiber of the present invention, for example, as shown in FIGS. 4A and 4B, pores 101 are formed only on the surface 102 of the fiber 100. Here, “only on the surface of the fiber” means that substantially only pores that are visible from the surface (for example, an image obtained by photographing the surface of the fiber with a scanning electron microscope) are formed on the surface of the fiber. Means that Thus, for example, a fiber-forming thermoplastic resin is mixed with a particulate material that can be extracted with a solvent, and after spinning the fiber, the particulate material is extracted using the solvent. It does not contain simple pores. Although such pores have openings on the fiber surface, there are many voids that cannot be seen from the surface inside the pores. It is different from the pores of the fiber.
[0053]
As long as the shape of the pores does not deviate from the concept of pores (as deviating from the concept of pores, for example, there are streaks, lines, strips, mountains, grooves, or hooks), It is not particularly limited and is preferably a semispherical shape. As for the “semispherical”, the description regarding the “semispherical” described above in the production method of the present invention is applied as it is. Moreover, it is preferable that the shape of the opening part on the fiber surface of the said pore is a substantially circular shape or a substantially polygonal shape. Here, the opening 103 is a contour formed by opening the pore 101 formed on the fiber surface 102 as shown in the pores illustrated in FIGS. 4 (a) and 4 (b). Point to. When the shape of the pore is hemispherical, or when the shape of the opening is substantially circular or substantially polygonal, the wiping effect by the pores, dust and liquid retention effect Or, excellent functions such as a dye fixing effect can be exhibited more effectively.
[0054]
The average diameter of the aperture is preferably 0.1 to 10 μm, more preferably 0.1 to 5 μm, and more preferably 0.1 to 3 μm. When the average diameter of the apertures is 0.1 to 10 μm, more effective functions such as a wiping effect due to the pores, a dust or liquid retention effect, or a dye fixing effect are more effectively exhibited. Can do. Here, the “average diameter of the aperture” means that the diameter of the circumscribed circle of the aperture that can be confirmed by magnifying and photographing the side surface of the fiber with a scanning electron microscope or the like The number average opening part diameter by sampling from arbitrary 500 places or more of is pointed out.
[0055]
Further, the major axis of the aperture is preferably 5 times or less of the minor axis, more preferably 3 times or less, and even more preferably 2 times or less. Here, the “major axis of the aperture” means the longest straight line among the straight lines connecting any two points on the outline of the aperture in the pores appearing on the image of the fiber side surface by a scanning electron microscope or the like. The “minor axis of the aperture” is the length of the longest straight line among any straight lines connecting two points where the straight line perpendicular to the major axis of the aperture and the outline of the aperture intersect. Refers to In addition, when there are three or more points where the outline of the aperture intersects with respect to one straight line perpendicular to the major axis of the aperture, the straight line connecting any two of these points The longest straight line is defined as a straight line connecting the two points. Further, the comparison value between the major axis and the minor axis of the aperture is a number average comparison value obtained by sampling from arbitrary 500 or more pores.
[0056]
The depth of the pore is not particularly limited as long as the pore is formed only on the surface of the fiber, and the average depth of the pore is preferably 0.1 to 10 μm, Preferably, it is 0.1-5 micrometers, More preferably, it is 0.1-3 micrometers. Here, the average depth of the pores means that the cross-section of the fiber is magnified and photographed with a laser microscope (for example, a high-definition confocal microscope manufactured by Lasertec Co., Ltd.) and confirmed with the image of the fiber. Regarding the depth of the deepest portion of each possible pore, the number average pore depth by sampling from arbitrary 500 or more pores of the fiber cross section can be used as the average depth of the pores. Here, as shown in FIGS. 4A and 4B, “depth of the deepest part of each pore” means a perpendicular line to the straight line 102 representing the fiber surface appearing on the image of the fiber cross section. When drawn, the length of the longest straight line (FIGS. 4A and 4B) connecting the intersection of the perpendicular and the inner wall of the pore and the intersection of the perpendicular and the straight line 102 representing the fiber surface (FIGS. 4A and 4B). B)).
[0057]
Further, in the pores appearing on the image of the cross section of the fiber in the fiber axis direction by a scanning electron microscope or the like, the length of the pore is preferably 0.6 to 3 times the opening width, and 0.7 to 2 times. More preferred. Here, as shown in FIGS. 4C and 4D, “the length of the pore” refers to the pore from one point A of both ends A and B representing the outline of the aperture. A half length of a path to another point B along a line representing the wall of the wall, and “aperture width” means the points A and B at both ends representing the outline of the aperture. It refers to the length a of the straight line to be connected. The comparison value between the pore length and the opening width is a number average comparison value obtained by sampling from arbitrary 500 or more pores.
[0058]
The number of pores is 100 μm on the fiber surface.²The number is preferably 10 to 1000, more preferably 20 to 500, and still more preferably 20 to 200. The number of the pores is 100 μm on the fiber surface.²When the number is about 10 to 1000 per unit, excellent functions such as a wiping effect by the pores, a dust or liquid holding effect, or a dye fixing effect can be more effectively exhibited.
[0059]
The pores are preferably pores generated by removing solid particles fixed on the fiber surface from the fiber surface. The method of making the pores into pores generated by removing solid particles fixed on the surface of the fiber from the surface of the fiber is, for example, the method for producing a surface porous fiber according to the present invention, or the present invention. According to the manufacturing method of the surface porous fiber sheet. Since the pores are generated by removing solid particles from the surface of the fiber, only the fiber surface is reliably made porous by the pores while maintaining the physical properties such as fiber strength inherent to the fiber. In addition, since the pores of the size as required according to the shape of the solid particles are formed, the wiping effect due to the porosity, the dust and liquid retention effect, the dye fixing effect, etc. according to the request , Can exhibit excellent functions.
[0060]
The surface porous fiber sheet of the present invention is not particularly limited as long as the fiber sheet includes at least the surface porous fiber of the present invention, and can include only the surface porous fiber of the present invention. Alternatively, fibers other than the surface porous fiber of the present invention can also be included. The fiber other than the surface porous fiber is not particularly limited, and at least the surface is a fiber mainly composed of a thermoplastic resin, or the surface is not a thermoplastic resin, for example, an inorganic fiber, or has a melting point. It can also be a fiber having a decomposition temperature.
[0061]
Examples of the structure of the fiber sheet include a woven fabric, a knitted fabric, a non-woven fabric, or a combination thereof. In the case of a woven fabric or a knitted fabric, it can be obtained, for example, by processing the fibers with a loom or a knitting machine. Moreover, in the case of a nonwoven fabric, it can be made into a fiber sheet by, for example, a conventional nonwoven fabric manufacturing method such as a dry method, a spunbond method, a melt blow method, a flash spinning method, or a wet method. In addition, the fiber web formed by these manufacturing methods is premixed with adhesive fibers and / or composite fibers in which two or more types of resins having different melting points are combined, and then the heat treatment is performed. It can be a bonded fiber sheet. Moreover, it can also be set as the fiber sheet which entangled between the said fiber webs by a mechanical entanglement process (for example, water flow entanglement or a needle punch). Alternatively, the fiber web may be passed between a heated smooth roll and a heated uneven roll to form a partially bonded fiber sheet. Moreover, it can also be set as the fiber sheet formed by laminating | stacking the said fiber sheet from which a kind differs, and further integrating.
[0062]
As a method of obtaining the surface porous fiber sheet of the present invention, for example, a method obtained by forming the sheet containing the surface porous fiber of the present invention as described above, or a fiber not containing the surface porous fiber Examples of the method include a method of forming pores by using the method for producing a surface porous fiber sheet according to the present invention after forming a sheet in advance. Thus, since the surface porous fiber sheet of the present invention has the surface porous fiber in the fiber sheet, the fiber sheet should be in a form suitable for various uses such as a wiper or a filter material. Thereby, the effect by the pore which the surface porous fiber has can be exhibited still more effectively.
[0063]
【Example】
EXAMPLES Hereinafter, the present invention will be specifically described by way of examples, but these do not limit the scope of the present invention.
[Example 1]
A core-sheath type composite fiber (fineness = 0.8 decitex, fiber length = 10 mm, fiber strength) in which the core component is polypropylene resin and the sheath component is high-density polyethylene resin (melting point = 132 ° C.) by the paper making apparatus A papermaking sheet comprising 2% / decitex) 100% was prepared. Next, this paper sheet is placed on a metal mesh conveyor belt, and the high density polyethylene fiber, which is an adhesive component of the composite fiber, is melted in an air-through dryer at a temperature of 140 ° C. Thermal bonding treatment was performed to obtain a wet method nonwoven fabric. This wet method nonwoven fabric has a surface density of 45 g / m.²Met.
[0064]
Next, sodium chloride manufactured by Wako Pure Chemical Industries was pulverized with a pulverizer to obtain sodium chloride fine particles having an average primary particle size of 2.5 μm. Next, using the apparatus shown in FIG. 1, the wet method nonwoven fabric was placed on a conveyor belt made of wire mesh, and the conveyor belt was moved. Next, using the apparatus shown in FIG. 1, a mixed gas stream in which the sodium chloride fine particles heated to 170 ° C. and air are mixed is prepared, and the mixed gas stream is added to the wet process nonwoven fabric from above the wet method nonwoven fabric. The fiber sheet was sprayed uniformly over the entire surface of the method nonwoven fabric to obtain a fiber sheet in which the sodium chloride fine particles were fixed mainly on one side of the wet method nonwoven fabric. Next, the fiber sheet is reversed and placed on a conveyor belt of a wire mesh, and the opposite surface of the fiber sheet is sprayed with a mixed airflow in the same manner, so that the sodium chloride fine particles are formed on the wet method nonwoven fabric. A fiber sheet adhered to both sides was obtained. This solid particle fixed sheet has an areal density of 80 g / m.²Met. Moreover, the solid particle fixed fiber contained in this solid particle fixed sheet was covered with a layer having a thickness of one particle of sodium chloride fine particles over the entire surface of the fiber. The photograph by the image which expanded the obtained solid particle fixed fiber 2000 times with the scanning electron microscope is shown in FIG.
[0065]
Next, the solid particle fixed sheet is poured into water, the sodium chloride fine particles fixed to the solid particle fixed sheet are dissolved in water, the sodium chloride fine particles are removed from the solid particle fixed sheet, and the fiber surface Only the surface porous fiber sheet which consists of the surface porous fiber in which the pore was formed was obtained. The surface density of the surface porous fiber sheet is 45 g / m.²Met. In addition, the surface porous fiber contained in the surface porous fiber sheet has a fiber surface of 100 μm over the entire fiber surface.²There were about 100 semicircular spherical pores, and the average diameter of the pores was 2.5 μm, corresponding to the average diameter of the fixed sodium chloride fine particles. Further, the depth of the pores was the depth corresponding to the above-described layer having a thickness corresponding to one particle of sodium chloride fine particles. Further, the fiber strength of the surface porous fiber was measured and found to be 4.2 g / dtex. The photograph by the image which expanded the surface porous fiber obtained by 2000 times with the scanning electron microscope is shown in FIG.
[0066]
[Example 2]
A fiber web made of 100% polypropylene fiber (fineness = 1.9 dtex, fiber length = 51 mm, fiber strength 6.5 g / dtex) made of polypropylene resin (melting point = 160 ° C.) was produced by a carding machine using a paper making apparatus. Then, the hydroentangled nonwoven fabric which entangled the fiber web by the hydroentanglement method was produced. This hydroentangled nonwoven fabric has a surface density of 40 g / m.²Met.
[0067]
Next, in Example 1, except that the hydroentangled nonwoven fabric was used instead of the wet method nonwoven fabric, and a mixed air stream in which the sodium chloride fine particles heated to 200 ° C. were mixed was used. In the same manner as in Example 1, a solid particle fixed sheet having sodium chloride fine particles fixed thereto was obtained. This solid particle fixed sheet has an areal density of 55 g / m.²Met. Moreover, the solid particle fixed fiber contained in this solid particle fixed sheet was covered with a layer having a thickness of one particle of sodium chloride fine particles over the entire surface of the fiber.
[0068]
Next, in the same manner as in Example 1, the solid particle fixed sheet was poured into water, and the sodium chloride fine particles fixed to the solid particle fixed sheet were dissolved in water. The surface porous fiber sheet which consists of surface porous fiber in which the pore was formed only on the surface of the fiber was obtained. The surface density of the surface porous fiber sheet is 40 g / m.²Met. In addition, the surface porous fiber contained in the surface porous fiber sheet has a fiber surface of 100 μm over the entire fiber surface.²There were 80 hemispherical pores, and the average diameter of the pores was 2.5 μm, corresponding to the average diameter of the fixed sodium chloride fine particles. Further, the depth of the pores was the depth corresponding to the above-described layer having a thickness corresponding to one particle of sodium chloride fine particles. The fiber strength of the surface porous fiber was measured and found to be 6.5 g / dtex.
[0069]
[Example 3]
A filamentous polypropylene fiber (fineness = 1.9 dtex, fiber strength 6.5 g / dtex) made of a polypropylene resin (melting point = 160 ° C.) was prepared.
Next, sodium chloride manufactured by Wako Pure Chemical Industries was pulverized with a pulverizer to obtain sodium chloride fine particles having an average primary particle size of 2.5 μm. Next, using the apparatus shown in FIG. 1, the filament was placed on a roll support, the roll support was rotated, and the filament was moved. Next, using the apparatus shown in FIG. 1, a mixed airflow in which the sodium chloride fine particles heated to 200 ° C. and air are mixed is prepared, and the mixed airflow is applied to the surface of the filament from above the filament. It sprayed so that it might become uniform over the whole, and the fiber which the sodium chloride fine particle fixed to the whole surface of this filament was obtained. Next, the sodium chloride fine particles that did not adhere to the fibers were removed by blowing away with a stream of room temperature to obtain solid particle fixed fibers to which the sodium chloride fine particles had been fixed. The mass of the sodium chloride fine particles fixed to the solid particle fixed fibers was 0.05 mg / m per unit length of the fibers. In addition, in the solid particle fixed fiber, the entire surface of the fiber was covered with a layer having a thickness equivalent to one particle of sodium chloride fine particles.
[0070]
Next, the solid particle fixed fiber is poured into water, the sodium chloride fine particles fixed to the solid particle fixed fiber are dissolved in water, the sodium chloride fine particles are removed from the solid particle fixed fiber, and the surface of the fiber Only the surface porous fiber which consists of the surface porous fiber in which the pore was formed was obtained. The fineness of the surface porous fiber was 1.9 dtex. Moreover, this surface porous fiber has a fiber surface of 100 μm over the entire fiber surface.²There were about 50 hemispherical pores, and the average diameter of the pores was 2.5 μm, corresponding to the average diameter of the fixed sodium chloride fine particles. Further, the depth of the pores was the depth corresponding to the above-described layer having a thickness corresponding to one particle of sodium chloride fine particles. The fiber strength of the surface porous fiber was measured and found to be 6.5 g / dtex.
In addition, the surface porous fiber is crimped to produce staple fibers cut to a length of 51 mm, and the fiber web is formed by performing a fiber opening process on a card machine. It was possible to obtain a fiber sheet comprising a good fiber web.
[0071]
[Comparative Example 1]
According to the method for producing a polypropylene-based porous fiber described in JP-A-5-125667 (Cited document 1), a polypropylene resin (melting point = 160 ° C.) and paraffin wax are mixed under melting, and this mixture is mixed. It is put into an extruder and melt-spun to obtain an unstretched fiber. Then, the unstretched fiber is stretched, then subjected to heat treatment, and then the paraffin wax is extracted and removed to obtain a filamentous polypropylene-based porous material. A fiber (fineness = 4.2 dtex) was obtained.
This filament-shaped polypropylene-based porous fiber formed pores that continued from the surface to the inside in the form of a flat hole, while the pores were repeatedly widened and narrowed in the fiber cross section. The fiber strength of the porous fiber was measured and found to be 1.5 g / dtex.
Next, this filament-shaped polypropylene-based porous fiber is crimped to produce a staple fiber cut to a length of 51 mm, subjected to a card machine to open the fiber, and an attempt was made to form a fiber web. It was difficult to form a fiber web because fiber breakage was severe and the card was clogged or hardly passed through the card.
[0072]
【The invention's effect】
According to the production method of the present invention, the solid particles are fixed only on the fiber surface of the fiber or the fiber surface of the fiber constituting the fiber sheet, and then the solid particles are removed. While maintaining the physical properties such as the above, only the fiber surface can be reliably made porous by the pores. In addition, since pores with the required size can be formed according to the shape of the solid particles, the wiping effect, the dust and liquid retention effect, or the dye fixing effect due to the pore formation can be met as required. In addition, it can exhibit excellent functions. Moreover, according to the manufacturing method of this invention, the surface porous fiber sheet containing such surface porous fiber or surface porous fiber can be obtained easily.
In addition, the surface porous fiber and the surface porous fiber sheet of the present invention have the fiber surface made porous by hemispherical pores while maintaining the physical properties such as fiber strength inherent to the fiber, and due to the porosity. It has excellent functions such as a wiping effect, dust and liquid retention effect, and dye fixing effect.
[Brief description of the drawings]
FIG. 1 is a schematic view schematically showing one embodiment of an apparatus used in a method for producing a surface porous fiber or surface porous fiber sheet of the present invention.
FIG. 2 is a photograph taken by a scanning electron microscope of a surface porous fiber according to an embodiment of the present invention. (Enlargement magnification = 2000 times)
FIG. 3 is a photograph taken with a scanning electron microscope of a solid particle-supporting fiber, which is an intermediate product before obtaining the surface porous fiber of FIG. (Enlargement magnification = 2000 times)
FIG. 4 is an explanatory view schematically showing one mode of pores of the surface porous fiber of the present invention.
[Explanation of symbols]
11 ... Blower; 12 ... Heating tube;
21 ... Supply container; 22 ... Supply control rotor; 23 ... Supply pipe;
29 ... solid particles;
30 ... Particle mixing means; 41 ... Nozzle;
50, 51, 52 ... heating means;
60, 61, 62 ... auxiliary heating means;
70... Roll or fiber support means;
70 '... roll or fiber sheet supporting means;
80 ... fiber; 80 'fiber sheet;
90: Adhesion processing chamber; 91: Indoor heating means
92 ... Particle recovery box;
93 ... Particle recovery means for blowing air
100 ... fiber
101 ... pore
102 ... Fiber surface
103 ... Open hole

Claims (11)

A method for producing a fiber having pores on the surface of at least a fiber mainly composed of a thermoplastic resin,
Solid particles having a melting point or decomposition temperature higher than the melting point of the thermoplastic resin are fixed to the fiber surface by fusing the fiber surface to form solid particle fixed fibers, and then the solid particles fixed fibers are solid. A method for producing a surface porous fiber, wherein particles are removed. A method of fixing the solid particles to the fiber surface by fusion of the fiber surface,
The solid particles are heated to a temperature equal to or higher than the melting point of the thermoplastic resin, and the heated solid particles are brought into contact with the fibers and fixed in a state maintained at a temperature equal to or higher than the melting point of the thermoplastic resin. Item 2. A method for producing a surface porous fiber according to Item 1.   The method for producing a surface-porous fiber according to claim 1 or 2, wherein the solid particles are a method of using water-soluble solid particles and a method of dissolving and removing solid particles of the solid particle-fixed fibers in water. .   A method of producing a fiber sheet having pores on the surface of the fiber sheet including fibers mainly comprising a thermoplastic resin at least on the surface, wherein the thermoplastic is obtained by fusing the fiber surface to the fiber surface. Production of a surface porous fiber sheet characterized in that solid particles having a melting point or decomposition temperature higher than the melting point of the resin are fixed to form solid particle fixed fibers, and then the solid particles of the solid particle fixed fibers are removed. Method. A method of fixing the solid particles to the fiber surface by fusion of the fiber surface,
The solid particles are heated to a temperature equal to or higher than the melting point of the thermoplastic resin, and the heated solid particles are brought into contact with the fiber sheet and fixed while being maintained at a high temperature equal to or higher than the melting point of the thermoplastic resin. The manufacturing method of the surface porous fiber sheet of Claim 4.   The method for producing a surface-porous fiber sheet according to claim 4 or 5, wherein the solid particles are a method of using water-soluble solid particles, and a method of dissolving and removing solid particles of the solid particle-fixed fibers in water. Method.   A surface-porous fiber in which pores are formed only on the surface of a fiber whose surface is mainly made of a thermoplastic resin, and the solid particles in which the pores are fixed to the surface of the fiber by melting the fiber surface are fibers. A surface-porous fiber characterized by being pores generated by being removed from the surface of the surface. The surface porous fiber according to claim 7 , wherein the shape of the opening of the pore is substantially circular or substantially polygonal, and the average diameter of the opening is 0.1 to 10 µm. The surface porous fiber according to claim 7 or 8 , wherein the average depth of the pores is 0.1 to 10 µm. The surface porous fiber according to any one of claims 7 to 9 , wherein the number of the pores is 10 to 1000 per 100 µm ² of the fiber surface. Containing surface porous fibers according to any one of claims 7-10, surface porosity of the fibrous sheet.

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