JP2007247072A - Conjugate fiber, non-woven fabric including conjugate fiber, split fiber non-woven fabric and use of the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a non-woven fabric excellent in flexibility and lint free property, and a conjugate fiber excellent in splitting property suitable for obtaining such the non-woven fabric. <P>SOLUTION: This conjugate fiber is formed by bringing a polyester (A) part into contact with a polyolefin (B) part to each other, wherein the polyester fiber (A) part is oriented and crystallized. Preferably the conjugate fiber has a splittable property. Also, the non-woven fabric consisting of such the conjugate fiber, a split fiber non-woven fabric obtained by splitting the polyester (A) part and the polyolefin (B) part, and its use such as a wiping cloth, etc.. are provided. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a nonwoven fabric that is excellent in flexibility and lint-free properties and that can be produced at low cost, a composite fiber that is excellent in splitting property composed of polyester and polyolefin suitable for obtaining the nonwoven fabric, a nonwoven fabric composed of composite fiber, and a split fiber nonwoven fabric And its manufacturing method and application.

  Nonwoven fabrics made of ultrafine fibers have excellent flexibility and are not only widely used as materials for clothing, disposable diapers, hygiene products, wiping cloths, etc., but because they are nonwoven fabrics, suspended particles in the air (hereinafter, (Referred to as particles), and it has been used in clean rooms and the like. A clean room is a limited space in which contamination control is performed, in which particles in the air are managed to a level below a limited cleanliness level, and electronic products and optics typified by semiconductor integrated circuits and display products. Widely used in the manufacturing process of products. For example, a semiconductor integrated circuit is manufactured by integrating elements such as transistors and capacitors and wirings connecting them on a silicon single crystal substrate. In this case, the constituent elements and wirings are managed on a scale of several hundred nm to several angstroms. For this reason, in the manufacturing process, mixing of submicron-sized particles directly leads to device defects and wiring defects, leading to a decrease in product yield when manufacturing semiconductor integrated circuits. In addition, since the manufacturing apparatus itself is an ultra-precise device manufactured for the purpose of controlling at the scale, not only the product yield is reduced, but the manufacturing apparatus may be damaged.

  Further, when manufacturing a display product, particles may cause defects in the display unit.

  In recent years, semiconductor integrated circuits have been increasingly miniaturized, and in the case of display products, the display portion has been increased in size and density. Under such circumstances, the influence of the mixing of particles into the manufacturing process on the yield reduction of these electronic products tends to be higher. Therefore, there is an increasing demand for reducing particles in the clean room. Wiping cloth is mentioned as a nonwoven fabric conventionally used in a clean room. As a conventionally used wiping cloth, for example, a nonwoven cloth wiping cloth made of cellulose long fibers is known. However, the cellulose long fiber is generated not a little by dropping of the fiber. Further, it is generally known that the wiping performance of the wiping cloth is improved by thinning the fiber, but the dropping of the fiber from the long cellulose fiber becomes more significant as the fiber becomes thinner. For this reason, the wiping cloth itself may become a particle generation source (hereinafter also referred to as dust generation), which is not preferable for use in a clean room in which particles are reduced in the future. Of the substances that can cause such particles, the fallen fibers are generally called lint.

  On the other hand, non-woven fabrics used in clean rooms are not limited to wiping cloths, and include clean clothes and masks. Such non-woven fabrics are also required to improve the feeling of wearing and to make the fibers extremely fine and, of course, not to be a source of particles.

  From such a background, there is a demand for a nonwoven fabric made of ultrafine fibers with less fiber dropping (lint).

  As a method for obtaining an ultrafine fiber nonwoven fabric, a method comprising treating a fabric composed of multicomponent filaments composed of a polymer having different water swellability or a plurality of incompatible polymer components with a high-pressure water stream (Patent Document 1), a thermoplastic resin As a composite of entangled nonwoven fabric (Patent Document 2) using a fiber-forming low-melting polymer having a melting point difference of 30 to 180 ° C. and an incompatible fiber-forming high-melting polymer, or two different types of resins A split type composite fiber mold having a predetermined fineness by discharging from a spinneret having a spinning nozzle is deposited on a collection belt to form a nonwoven fabric, and a fineness 0.01 obtained by applying an extension force is 0.01. Nonwoven fabrics by various methods such as ultrafine fiber nonwoven fabrics of -2.0 denier (Patent Document 3) have been proposed.

  However, the composite fiber composed of components whose melting point difference specifically exceeds 30 ° C. specifically described in Patent Document 1 and Patent Document 2 may be insufficiently divided, and the process is complicated for sufficient division. Become. Also, lint from non-woven fabrics is not uncommon. Furthermore, since the difference in melting point is large, a temperature difference occurs during molding, and the low molecular weight component of the polymer on the low melting point side is gasified and adheres to the nozzle surface, and yarn breakage occurs due to temperature unevenness in the nozzle. As a result, there is a problem of greatly reducing productivity.

  Further, in Patent Document 2, when the melting point difference between the two polymers is less than 30 ° C., the high melting point polymer adversely affects the low melting point polymer in the point thermocompression bonding step after forming the web. It is described as being unfavorable because the web tends to shrink and the web tends to shrink, resulting in poor dimensional stability, or the adhesive temperature range at the time of thermocompression bonding becomes narrow and temperature control becomes difficult. No specific example using a polymer having a melting point difference of less than 30 ° C. is described.

In Patent Document 3, for example, when used for clothing or wiping cloth used in a clean room, the nonwoven fabric is fluffy, or the nonwoven fabric is fluffy, and the fine fibers are not dropped (lint). To do.
Japanese Patent Publication No. 2-14458 Japanese Patent Publication No. 7-49619 International Publication WO2005 / 042824

  The present invention is excellent in flexibility, and is not a source of particles even when used for an application where the surface of a nonwoven fabric is rubbed, such as clothing used in a clean room or a wiping cloth. Various studies were conducted for the purpose of obtaining a non-woven fabric excellent in freeness and a composite fiber excellent in splitting property suitable for obtaining such a non-woven fabric at low cost. As a result, surprisingly, it was found that the object of the present invention can be achieved by orientation-crystallizing the polyester (A) part of the composite fiber in which the polyester (A) part and the polyolefin (B) part are in contact with each other. It was.

  That is, the present invention provides a composite fiber in which a polyester (A) part and a polyolefin (B) part are in contact with each other, and the polyester (A) part is oriented and crystallized, preferably Provided are a composite fiber having splitting properties, a nonwoven fabric composed of such composite fibers, a split fiber nonwoven fabric obtained by splitting a polyester (A) part and a polyolefin (B) part of the composite fiber, and uses thereof.

  In the present invention, polyester (A) and polyolefin (B) used for the composite fiber have a melting point difference [melting point (Tme) of polyester (A) −melting point (Tmo) of polyolefin (B)] of 5 to 30 ° C. The composite fiber according to the preceding item in the range of less than the above, a nonwoven fabric composed of the composite fiber, a split fiber nonwoven fabric obtained by dividing the composite fiber polyester (A) part and the polyolefin (B) part, a method for producing the nonwoven fabric, and use thereof It is to provide.

  The split fiber nonwoven fabric of the present invention can be split with a low-energy high-pressure liquid flow (excellent splitting property) when splitting into a polyester (A) portion and a polyolefin (B) constituting the composite long fiber, and the composite long fiber The split fiber nonwoven fabric obtained by splitting is characterized by excellent flexibility, strength, and lint-free properties because the polyester (A) portion is oriented and crystallized.

Polyester (A)
Polyester (A), which is one of the components constituting the conjugate fiber of the present invention, is a variety of known polyesters and is a polymer that undergoes orientational crystallization during melt spinning.

  Among these polyesters (A), a polymer having a melting point (Tme) in the range of 100 to 300 ° C, more preferably 150 to 300 ° C is preferable. When the melting point (Tme) is lowered, it may be difficult to orientate and crystallize the polyester portion when spinning with polyolefin (B) described later to obtain a composite fiber, while the melting point (Tme) is 300 ° C. When the value becomes high, sufficient cooling cannot be performed at the time of spinning, and the filaments may be fused due to a cooling delay.

  The melting point (Tme) and crystallization temperature of the polyester (A) according to the present invention were measured using a differential scanning calorimeter (DSC) by the following known method. Temperature rising rate: The temperature is raised to a temperature 50 ° C. higher than the temperature that gives the extreme value of the melting endothermic curve when the temperature is raised at 10 ° C./min. After holding at this temperature for 10 minutes, the temperature lowering rate: 10 ° C./min The melting curve when the temperature was raised to a predetermined temperature at 10 ° C./min was measured again, and from this melting curve, the method of ASTM D3419 was followed to determine the extreme end of the melting endothermic curve. The temperature (Tp) giving the value was determined, the endothermic peak at this peak temperature was taken as the melting point (Tme), and the temperature giving the extreme value of the solidification exothermic curve was taken as the crystallization temperature.

  As long as the polyester (A) according to the present invention can be melt-spun, the melt flow rate (MFR, ASTM D-1238) is not particularly limited. For example, when polylactic acid is used, the MFR under a load of 2160 g at 190 ° C. is usually in the range of 1 to 500 g / 10 minutes, preferably 5 to 100 g / 10 minutes, more preferably 10 to 50 g / 10 minutes. When polyethylene terephthalate is used, the intrinsic viscosity [η] obtained by measurement at 20 ° C. in a mixed solvent of phenol: tetrachloroethane = 1: 1 is usually 0.1 to 1.2, preferably 0.3. It is -1.0, More preferably, it exists in the range of 0.5-0.8 dl / g.

  Such polyester (A) includes an aliphatic or alicyclic dicarboxylic acid component (a1), a dicarboxylic acid component (a2) such as an aromatic dicarboxylic acid component (a2) and an aliphatic or alicyclic dihydroxy compound component (b1). A polyester obtained by polymerizing the dihydroxy compound component (b) and, if necessary, the bifunctional aliphatic hydroxycarboxylic acid component (c1), or the bifunctional aliphatic hydroxycarboxylic acid component (c1) or lactones (c2) This is a polyester obtained by polymerization.

  Specific examples of the polyester (A) include polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyethylene terephthalate / isophthalate copolymer, polyethylene naphthalate, and poly 1,4-cyclohexylene dimethylene terephthalate. Examples include aromatic polyesters, poly-3-hydroxybutyrate, poly-3-hydroxyvalerate, polycaprolactone, polyethylene succinate, polybutylene succinate, polylactic acid, polyglycolic acid or aliphatic polyesters such as copolymers thereof. Although not limited to such polyesters.

  In the polyester (A), an antioxidant, a weather resistance stabilizer, a light resistance stabilizer, an antistatic agent, an antifogging agent, an antiblocking agent, a lubricant, a nucleating agent, and a pigment are used as long as the object of the present invention is not impaired. Such additives or other polymers can be blended as necessary.

Aliphatic or alicyclic dicarboxylic acid component (a1)
The aliphatic or alicyclic dicarboxylic acid component (a1), which is one of the components constituting the polyester (A), is not particularly limited, but usually the aliphatic dicarboxylic acid component has 2 to 10 carbon atoms (carboxyl). (Including the carbon of the group), preferably a compound having 4 to 6 carbon atoms, which may be linear or branched. The alicyclic dicarboxylic acid component is usually preferably one having 7 to 10 carbon atoms, particularly 8 carbon atoms.

  Further, the aliphatic or alicyclic dicarboxylic acid component (a1) has a larger number of carbon atoms, for example, up to 30 carbon atoms, as long as the main component is an aliphatic dicarboxylic acid having 2 to 10 carbon atoms. The dicarboxylic acid component can be included.

  Specific examples of the aliphatic or alicyclic dicarboxylic acid component (a1) include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, azelaic acid, sebacic acid, fumaric acid, 2, 2-dimethylglutaric acid, suberic acid, 1,3-cyclopentadicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, diglycolic acid, itaconic acid, maleic acid and 2,5-norbornanedicarboxylic acid Dicarboxylic acids such as acids, dimethyl esters, diethyl esters, di-n-propyl esters, di-isopropyl esters, di-n-butyl esters, di-isobutyl esters, di-t-butyl esters, di-n of such dicarboxylic acids -Pentyl ester, di-isopentyl ester or di-n-hexyl ester It can be exemplified an ester-forming derivative such as ether.

  These aliphatic or alicyclic dicarboxylic acids or ester-forming derivatives thereof can be used alone or as a mixture of two or more.

Aromatic dicarboxylic acid component (a2)
The aromatic dicarboxylic acid component (a2) which is one of the components constituting the polyester (A) is not particularly limited, but usually a compound having 8 to 12 carbon atoms, particularly having 8 carbon atoms. Compounds.

  Specific examples of the aromatic dicarboxylic acid component (a2) include terephthalic acid, isophthalic acid, 2,6-naphthoic acid, 1,5-naphthoic acid, and ester-forming derivatives thereof. Specific examples of ester-forming derivatives of aromatic dicarboxylic acids include di-C1-C6 alkyl esters of aromatic dicarboxylic acids such as dimethyl ester, diethyl ester, di-n-propyl ester, di-isopropyl ester, di- Examples thereof include n-butyl ester, di-n-butyl ester, di-isobutyl ester, di-t-butyl ester, di-n-pentyl ester, di-isopentyl ester and di-n-hexyl ester. These aromatic dicarboxylic acids or ester-forming derivatives thereof can be used alone or as a mixture of two or more.

Aliphatic or alicyclic dihydroxy compound component (b1)
The aliphatic or alicyclic dihydroxy compound component (b1), which is one of the components constituting the polyester (A), is not particularly limited, but usually 2 to 12 carbons if the aliphatic dihydroxy compound component is used. If it is a branched or linear dihydroxy compound having 4 to 6 carbon atoms, preferably an alicyclic dihydroxy compound component, a cyclic compound having 5 to 10 carbon atoms can be mentioned.

  Specific examples of the aliphatic or alicyclic dihydroxy compound component (b1) include ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, and 1,4-butane. Diol, 1,5-pentanediol, 2,4-dimethyl-2-ethylhexane-1,3-diol, 2,2-dimethyl-1,3-propanediol, 2-ethyl-2-butyl-1,3 -Propanediol, 2-ethyl-2-isobutyl-1,3-propanediol, 2,2,4-trimethyl-1,6-hexanediol, in particular ethylene glycol, 1,3-propanediol, 1,4 -Butanediol and 2,2-dimethyl-1,3-propanediol (neopentyl glycol); cyclopentanediol, 1,4-cycl Hexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol and 2,2,4,4-tetramethyl-1,3-cyclobutanediol and diethylene glycol, triethylene Examples thereof include polyoxyalkylene glycols such as glycol and polyoxyethylene glycol, and polytetrahydrofuran, and particularly include diethylene glycol, triethylene glycol and polyoxyethylene glycol or a mixture thereof or a compound having a different number of ether units. The aliphatic or cycloaliphatic dihydroxy compound component can also be a mixture of different aliphatic or cycloaliphatic dihydroxy compounds.

Bifunctional aliphatic hydroxycarboxylic acid component (c1)
The bifunctional aliphatic hydroxycarboxylic acid component (c1), which is one of the components constituting the polyester (A), is not particularly limited, but is usually a branched or linear divalent having 1 to 10 carbon atoms. The compound which has an aliphatic group is mentioned.

  Specific examples of the bifunctional aliphatic hydroxycarboxylic acid component (c1) include glycolic acid, L-lactic acid, D-lactic acid, D, L-lactic acid, 2-methyllactic acid, 3-hydroxybutyric acid, 4 -Hydroxybutyric acid, 2-hydroxy-n-butyric acid, 2-hydroxy-3,3-dimethylbutyric acid, 2-hydroxy-2-methylbutyric acid, 2-hydroxy-3-methylbutyric acid, hydroxypivalic acid, hydroxyisocaproic acid, Bifunctional aliphatic hydroxycarboxylic acid ester-forming derivatives such as hydroxycaproic acid and the like, such as methyl ester, ethyl ester, propyl ester, butyl ester and cyclohexyl ester of bifunctional aliphatic hydroxycarboxylic acid.

Lactones (c2)
Examples of the lactone (c2) that is one of the components constituting the polyester (A) include lactones such as ε-caprolactone, δ-valerolactone, and β-methyl-δ-valerolactone.

Polyolefin (B)
Polyolefin (B) which is one of the components constituting the conjugate fiber of the present invention is various known polyolefins, specifically, for example, α-olefins having 2 to 10 carbon atoms such as ethylene, propylene, 1- Homopolymers or copolymers of butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-decene, α-olefins having 2 to 10 carbon atoms and a small amount of vinyl acetate, It can be obtained from a copolymer with a vinyl ester having a vinyl group such as methyl acrylate, methyl methacrylate, ethyl acrylate or ethyl methacrylate, or an aromatic vinyl compound having a vinyl group such as styrene or α-methylstyrene. Polymers such as polystyrene and ethylene / styrene copolymers are also included. Of these polyolefins, crystalline polyolefins are preferred.

  Among these polyolefins (B), a polymer having a melting point (Tmo) in the range of 100 to 350 ° C, more preferably 100 to 300 ° C is preferable. When the melting point (Tmo) is low, it may be difficult to orient and crystallize the polyolefin part when spinning with the polyester (A) to obtain a composite fiber, while when the melting point (Tmo) is high, the polyolefin In this case, it is difficult to sufficiently cool at the time of spinning, and a fusion delay may occur due to a cooling delay.

  The melting point (Tmo) and crystallization temperature of the polyolefin (B) according to the present invention were measured by the following known method using a differential scanning calorimeter (DSC). (DSC) was used in the following known method. Temperature rising rate: The temperature is raised to a temperature 50 ° C. higher than the temperature that gives the extreme value of the melting endothermic curve when the temperature is raised at 10 ° C./min. After holding at this temperature for 10 minutes, the temperature lowering rate: 10 ° C./min The melting curve when the temperature was raised to a predetermined temperature at 10 ° C./min was measured again, and from this melting curve, the method of ASTM D3419 was followed to determine the extreme end of the melting endothermic curve. The temperature (Tp) giving the value was determined, the endothermic peak at this peak temperature was taken as the melting point (Tme), and the temperature giving the extreme value of the solidification exothermic curve was taken as the crystallization temperature.

  The polyolefin (B) according to the present invention has a melt flow rate (MFR: ASTM D-1238, a load of 2160 g, as long as it can be melt-spun, but an ethylene polymer, a 1-butene polymer, and an ethylene / acid (derivative). The copolymer is measured at 190 ° C., the propylene polymer is measured at 230 ° C., and the 4-methyl / 1-pentene polymer is measured at 260 ° C.), but it is usually 1 to 100 g / 10 minutes, preferably 5 It is in the range of ˜500 g / 10 min, more preferably 10 to 100 g / 10 min. The ratio Mw / Mn of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the polyolefin (B) according to the present invention is usually 1.5 to 5.0. From the viewpoint of obtaining a composite fiber having good spinnability and particularly excellent fiber strength, 1.5 to 3.0 is more preferable. In the present invention, good spinnability means that yarn breakage does not occur during discharge from the spinning nozzle and during drawing, and filament fusion does not occur. In the present invention, Mw and Mn can be measured by a known method by GPC (gel permeation chromatography).

  Specific examples of these polyolefins (B) include ethylene homopolymers or one or more α-types such as ethylene and propylene, 1-butene, 1-hexene, 4-methyl / 1-pentene, and 1-octene. Ethylene polymers known as copolymers with olefins, such as high-pressure low-density polyethylene, linear low-density polyethylene (so-called LLDPE), medium-density polyethylene, and high-density polyethylene; propylene homopolymer (polypropylene) or propylene And propylene / ethylene random copolymer, which is a copolymer of ethylene, 1-butene, 1-hexene, 4-methyl / 1-pentene, 1-octene and the like with one or more α-olefins, propylene / ethylene / 1-butene random copolymer, propylene / 1-butene random copolymer (polypropylene 1-butene polymers such as poly 1-butene, 1-butene / ethylene random copolymers, 1-butene / propylene random copolymers; poly 4-methyl 4 such as a copolymer of 1-pentene, 4-methyl / 1-pentene / 1-decene random copolymer, 4-methyl / 1-pentene and one or more α-olefins having 12 to 20 carbon atoms -Methyl / 1-pentene polymer; ethylene / acid such as ethylene / vinyl acetate copolymer (EVA), ethylene / (meth) acrylic acid copolymer, ethylene / (meth) acrylic acid ester copolymer, ionomer (Derivative) copolymer; Ethylene / styrene copolymer, crystalline polystyrene such as isotactic polystyrene; These polyolefins may be used alone or in combination of two or more.

  For polyolefin (B), antioxidants, weathering stabilizers, light stabilizers, antistatic agents, antifogging agents, antiblocking agents, lubricants, nucleating agents, and pigments that are usually used are within the range not impairing the object of the present invention. Such additives or other polymers can be blended as necessary.

Composite fiber The composite fiber of the present invention is a composite fiber in which a portion made of the polyester (A) and a portion made of the polyolefin (B) are in contact with each other, and the polyester (A) is oriented and crystallized. The composite fiber is preferably a composite fiber in which the polyester (A) part and the polyolefin (B) part are in contact with each other, the polyester (A) is oriented and crystallized, and the polyolefin (B) part is A composite fiber formed by crystallization, more preferably a composite fiber formed by contacting a part made of the polyester (A) and a part made of the polyolefin (B) with each other, and the polyester (A) is oriented and crystallized, The polyolefin (B) part is crystallized, and the polyester (A) and the polyolefin (B) have a property of being divided. Is a case fibers (also referred to as a split type composite fiber).

  The shape (cross section) of the composite fiber is not particularly limited as long as the polyester (A) portion and the polyolefin (B) portion are in contact with each other, but it is divided as shown in FIG. 1 (a) to FIG. 1 (d). It is particularly preferable to have the property of being easily processed.

  The fineness of the conjugate fiber of the present invention is usually preferably 6 denier or less. If it is 6 deniers or less, it is preferable because the fineness after the division treatment can be reduced and the wiping property and flexibility are excellent. Further, the number of divisions of the polyester (A) part and the polyolefin (B) part forming the composite fiber is not particularly limited as long as it does not impair the division property, but usually 4 to 48 divisions, preferably 4 to 24 divisions. Is in range. By setting the fineness of the composite fiber and the splitting of the composite fiber in such a range, the fineness of the split fiber obtained by splitting the nonwoven fabric made of the composite fiber is 0.001 to 2.00 denier, preferably 0.001 to 1.. It can be in the range of 2 denier.

Nonwoven Fabric The nonwoven fabric of the present invention is composed of the above-mentioned composite fiber, and usually has a basis weight of 3 to 200 g / m ² , preferably 10 to 150 g / m ² . Moreover, the nonwoven fabric of this invention is heat-seal | fused by methods, such as an embossing roll and ultrasonic fusion | bonding, as needed. The area (embossed area ratio) in the case of heat-sealing can be appropriately selected according to the use, but is preferably 5 to 30%.

Split fiber nonwoven fabric The split fiber nonwoven fabric of the present invention is a nonwoven fabric obtained by splitting a polyester (A) part and a polyolefin (B) part that form a composite fiber by applying stress to the nonwoven fabric made of the composite fiber. Usually, it is in the range of 3 to 200 g / m ² , preferably 10 to 150 g / m ² .

  The fineness of the split fibers forming the split fiber nonwoven fabric of the present invention is usually in the range of 0.001 to 2.0 denier, preferably 0.001 to 1.2 denier.

  The split fiber nonwoven fabric of the present invention is excellent in lint-free properties, specifically, the number of dust particles of 25 μm or less in a test based on JIS-B-9923 (tumbling method) described in Examples is usually 5000 or less, The range is preferably 3000 or less.

  Various known methods, for example, a method of applying a liquid such as water at a high pressure, a so-called high-pressure water flow method (water jet method) can be used as the stress applied to the nonwoven fabric made of the composite fiber. Among them, the method of applying a liquid such as water at a high pressure is preferable in that a non-woven fabric composed of ultrafine fibers can be easily obtained by efficiently dividing a split composite fiber.

  The nonwoven fabric according to the present invention may be a laminate of other nonwoven fabric, spunbond nonwoven fabric or meltblown nonwoven fabric depending on the purpose of use. Moreover, you may laminate | stack with a film or a porous film. For example, a laminate of a spunbond nonwoven fabric and a split fiber nonwoven fabric having a relatively large fiber diameter is a preferable form for wiping cloth applications in which dust having a large particle diameter and dust having a small particle diameter are simultaneously wiped. As a method for joining a split type composite fiber nonwoven fabric and a nonwoven fabric produced by another manufacturing method, entanglement treatment by means such as the above needle punch, water jet, ultrasonic seal or the like, heat fusion treatment by a heat embossing roll, and adhesion Known methods such as agent bonding may be mentioned.

Wiping cloth The wiping cloth of the present invention has the split fiber nonwoven fabric on the wiping surface. By using such a split fiber nonwoven fabric for the wiping surface of the wiping cloth, a wiping cloth with less lint generation and excellent wiping property can be obtained.

Articles for Clean Rooms The nonwoven fabric of the present invention is excellent in lint-free properties and is unlikely to become a particle generation source, and therefore is particularly preferably used as an article (nonwoven fabric) used in a clean room, that is, an article for a clean room. Examples of clean room articles include crane room wiping cloths, clean room clothing, clean room masks, and the like.

  When used for a clean room, it is preferable to perform a cleaning process to remove adhering atmospheric dust and the like, for example, in a clean room of ISO class 5 (FDIS 14644-1, 1997). Washed with water or warm water (conductivity 4-6 microohms / cm) pre-generated by reverse osmosis using an ionic surfactant, and used in semiconductor manufacturing processes with a specific resistance of 15 MΩ · cm or more Examples thereof include a step of sufficiently washing with water having the same specifications as so-called ultrapure water, followed by drying and packing in the atmosphere.

  Moreover, the method of incorporating a washing | cleaning process into the manufacturing process of a nonwoven fabric may be used by making the manufacturing environment of a nonwoven fabric into a clean room, and using the ultrapure water used in a semiconductor manufacturing process as the high-pressure water stream at the time of division | segmentation.

Production method of conjugate fiber and conjugate fiber nonwoven fabric The nonwoven fabric comprising the conjugate fiber and conjugate fiber of the present invention can be obtained by a known melt spinning production method using the polyester (A) and polyolefin (B). The spunbond method is preferred in that the productivity is good and a high-strength filament can be obtained.

  As a method for producing the composite fiber nonwoven fabric of the present invention, a spunbond method will be described as an example. The polyester (A) and the polyolefin (B) are separately melted by an extruder or the like, and the melts are radially or parallel or parallel as illustrated in FIGS. 1 (a) to 1 (d). The composite fiber is spun by discharging from a spinneret having a composite spinning nozzle adapted to form a cross-sectional structure.

  At this time, considering the decomposition of the resin polyester (A) and the polyolefin (B), the melting temperature of the resin is 20 to 40 ° C. higher than the melting point on the high temperature side among the melting points of the polyester (A) or the polyolefin (B). It is preferable to carry out within a range.

  The spun composite long fiber is cooled by a cooling fluid, and further, the long fiber is tensioned by drawing air to reduce the fineness to a predetermined fineness, and is collected as it is on a collecting belt and deposited to a predetermined thickness. . Next, heat embossing is performed as necessary by heat fusion using a heat embossing roll. In the case of heat fusion with a hot embossing roll, the embossing area ratio of the embossing roll is appropriately determined, but is usually preferably 5 to 30%.

  At this time, it is necessary that the polyester (A) is oriented and crystallized by appropriately selecting a molding temperature, a spinning speed, and a cooling air temperature in a range where the spinnability is good. The orientation crystallization of the polyester (A) referred to here is evaluated by a known X-ray crystallinity evaluation method.

  The details of the reason why a non-woven fabric having better lint-free properties can be obtained when oriented and crystallized are unclear, but the fiber structure is further strengthened by crystal orientation in the fiber axis direction. It is estimated to be.

Hereinafter, orientation crystallization of the present invention, that is, crystallinity and orientation will be described in detail.
Evaluation of crystallinity and orientation by X-ray has been introduced in many known literatures for a long time, and is an evaluation method established as a structural analysis of polymers at present. For example, edited by the Society of Polymer Science, “Polymer Experimental Laboratory Volume 2”, Kyoritsu Publishing (1958). Supervised by Isa Nita, “X-ray crystallography, above”, Maruzen (1959). Kadoto, Kawai, Saito, “Polymer Structure and Properties”, Yukichi Kure, Teruichiro Kubo, Koka, 39, 929 (1939). The evaluation of oriented crystallinity in the present invention is based on the evaluation methods of these known documents. Specifically, for crystallinity, the X-ray total scattering intensity curve of the wide-angle X-ray diffraction profile is used to determine the scattering contribution of the crystalline region and the scattering of the amorphous region. Separated into contributions, the ratio of each area to the total area was evaluated as the crystallinity index value. For example, polylactic acid is known to have crystalline diffraction peaks around 2θ: 16 ° and 18 °, and for example, polyethylene terephthalate has crystalline diffraction peaks around 2θ: 17 °, 18 °, and 26 °. For example, polytrimethylene terephthalate has crystalline diffraction peaks at 2θ: 9 °, 15 °, 17 °, 19 °, 23 °, 25 °, 28 °, and 29 °. In addition, for example, polybutylene terephthalate is known to have crystalline diffraction peaks around 2θ: 9 °, 16 °, 17 °, 20 °, 23 °, 25 °, and 29 °. Evaluation is made by separating the amorphous region from the region to which the crystalline diffraction peak contributes as a crystalline region.

Regarding the orientation, in the azimuth distribution curve (X-ray interference diagram) obtained by measuring the azimuth distribution strength of the crystal plane peak in the crystallinity evaluation, the fiber from the peak half-value width (α) according to the following formula: The degree of orientation in the axial direction (generally, the degree of c-axis orientation) is calculated and evaluated.

Degree of orientation (F) = (180 ° −α) / 180 °
(Α is the peak half-value width in the azimuth distribution curve)

  Regarding the crystallinity of the composite fiber composed of the polyester (A) and the polyolefin (B), a crystal peak may be observed on the polyester side, but the crystallinity index value determined by X-ray diffraction is usually 5 or more, preferably 10 More preferably, it is 20 or more. The degree of orientation is usually 0.8 or more, preferably 0.85 or more, and more preferably 0.9 or more.

  The polyester (A) and the polyolefin (B) are not particularly limited as long as the polyester (A) can be oriented and crystallized when the composite fiber is formed, but if manufacturing stability (stability during spinning) is taken into consideration. The polyester (A) is preferably at a higher temperature than the polyolefin (B), and the difference in melting point between the polyester (A) and the polyolefin (B) used [melting point (Tme) of the polyester (A) −melting point of the polyolefin (B) ( Tmo)] is oriented to crystallize polyester (A) more easily by selecting polyester (A) and polyolefin (B) each having a temperature in the range of less than 5 to 30 ° C., preferably in the range of 10 to 25 ° C. Can do. In the case of a combination having a melting point difference of 30 ° C. or more, the resin on the high melting point side is solidified in stretching at the time of melting faster than the resin on the low melting point side, and stress is concentrated. The surface is easily covered with the low melting point resin. As a result, it is presumed that it is difficult to divide the resulting conjugate fiber, and that the covering portion is unnecessarily split and lint occurs in order to divide the covered portion. In addition, it is necessary to mold at a high temperature to melt the high melting point polymer, so that the polymer on the low melting point side is easily decomposed. This can reduce productivity. Not only does productivity decrease. There is a possibility that the non-woven fabric obtained by increasing the low molecular weight component in the non-woven fabric can be a source of organic volatile components. This organic volatile component is a cause of device formation failure particularly in the device formation process when manufacturing a semiconductor integrated circuit. Therefore. In particular, when used in the vicinity of the process, it is preferable to suppress the generation of this organic volatile component. Further, a crystal nucleating agent may be added in order to promote oriented crystallization of the polyester (A). Examples of crystal nucleating agents include biodegradable polyesters having a nucleating agent effect such as polybutylene succinate, zinc phenylphosphonate, melamine polyphosphate, melamine cyanurate, talc, boron nitride, calcium carbonate, titanium oxide, etc. Can do.

  From such a viewpoint, as a combination with the polyester (A) and the polyolefin (B) forming the composite fiber of the present invention, poly-L-lactic acid or poly-D- having a melting point (Tme) in the range of 150 to 180 ° C. A polylactic acid polymer such as lactic acid, a copolymer obtained by copolymerizing L-lactic acid and a small amount of D-lactic acid, or a copolymer obtained by copolymerizing D-lactic acid and a small amount of L-lactic acid; , Propylene / ethylene random copolymers having a melting point (Tmo) of 135 to 162 ° C., propylene / 1-butene random copolymers, propylene / α-olefins such as propylene / ethylene / 1-butene random copolymers A random copolymer and a propylene-based polymer such as a propylene homopolymer, [polyester (A) melting point (Tme) -polyolefin (B) melting point (T o)] is to be less than 5 to 30 ° C., preferably those appropriately selected. Among these, a combination of a polylactic acid polymer and a propylene / α-olefin random copolymer is most preferable in consideration of the fact that the polylactic acid polymer can be easily oriented and crystallized as described later.

  Other polyester (A) and polyolefin (B) combinations include polyethylene terephthalate having a melting point (Tme) of 260 ° C. and 4-methyl / 1-pentene / 1-decene random copolymer having a melting point (Tmo) of 238 ° C. It is most preferable to select a polymer in which the difference in melting point between the polyester (A) and the polyolefin (B) falls within the above range.

Manufacturing method of split fiber nonwoven fabric The split fiber nonwoven fabric of the present invention can be manufactured by applying stress to the nonwoven fabric composed of the composite fiber by a high-pressure liquid flow or the like. In this step, after the nonwoven fabric is obtained by the known melt spinning production method, the treatment with the high-pressure liquid flow may be continuously performed.

  In the case of applying a high-pressure water flow to a nonwoven fabric composed of composite fibers, specifically, for example, before the split splitting and entanglement applying step by the high-pressure liquid flow, between the constituent single yarns of the nonwoven fabric in order to promote entanglement etc. It is preferred to replace the air present in the water with water. Specifically, water may be applied to the web.

A high-pressure liquid flow can be obtained by injecting the liquid through a nozzle hole and increasing the pressure with a high-pressure pump. As a nozzle hole, a hole diameter is 0.05-1.0 mm normally, More preferably, it exists in the range of 0.1-0.5 mm. The pressure of the high-pressure liquid flow is usually in the range of 50 to 600 kgf / cm ² , preferably 50 to 250 kgf / cm ² . In addition, water or warm water is applied as the liquid for ease of handling, and pure water having a specific resistance value of 10 MΩ · cm or more, more preferably 15 MΩ · cm or more, is used with a known water quality measuring apparatus.

  The distance between the nozzle hole and the nonwoven fabric is preferably about 1 to 15 cm. When this distance exceeds 15 cm, the energy given to the nonwoven fabric by the liquid decreases, and the effect of splitting and entanglement of the composite fiber tends to decrease. Moreover, when it becomes less than 1 cm, the formation of the nonwoven fabric tends to be disturbed.

  Generally, the nozzle holes of the high-pressure liquid stream are arranged in a row in a direction intersecting with the traveling direction of the nonwoven fabric. In the case of single-sided treatment, in order to obtain uniform division of the composite fiber and tight entanglement bonding, it is preferable to carry out the injection holes in two or more rows, preferably three or more rows. The pressure of the high-pressure liquid stream is preferably low on the front side and high on the rear side in order to make the formation uniform.

  Furthermore, the pattern of the nonwoven fabric according to the present invention can be changed by appropriately selecting the pattern of the screen belt used when processing the high-pressure liquid flow.

  The non-woven fabric that has been subjected to the division treatment with the high-pressure liquid flow is then dried and heat-treated after the excess water is removed by mechanical squeezing into a final product. The heat treatment temperature time can be selected not only to remove moisture but also to allow moderate shrinkage and promotion of crystallization. The heat treatment may be a dry heat treatment or a wet heat treatment.

  EXAMPLES Hereinafter, although this invention is shown by an experiment example, this invention is not limited by the following experiment examples. In addition, the measurement of the division ratio of the nonwoven fabric obtained in the experimental example, the texture, the fineness, the softness, the tensile strength, the evaluation on the lint-free property, and the analysis of the fiber structure were performed by the following methods.

(1) Dividing ratio The obtained divided fiber nonwoven fabric is embedded in an epoxy resin, and then cut with a microtome to obtain a sample piece. When this is observed with an electron microscope (S-3500N scanning electron microscope manufactured by Hitachi, Ltd.) and the number of segments of the divided fiber cross section observed from the obtained cross-sectional image is 1, the division ratio is 100%. When the observed number of segments in the cross section of the split fibers was two or more, the split ratio was calculated by the following formula. This was observed for 50 fibers, and the average value was taken as the split ratio of the split fiber nonwoven fabric.

Dividing ratio [%] = (total number of segments−number of observed segments of divided fiber cross section) / total number of segments × 100

Here, the total number of segments refers to the total number of segments forming the filament cross section of the split composite fiber. For example, in the case of a split type composite fiber having a filament cross section as shown in FIGS.
For example, when a split fiber cross section as shown in FIG. 1 (e) is observed in a filament with a total number of segments of 8 as shown in FIG. 1 (a), the number of segments of the observed split fiber cross section is set to 3, Further, the division ratio is 62.5%.

(2) Fineness The obtained split fiber nonwoven fabric is embedded in an epoxy resin, and then cut with a microtome to obtain a sample piece. Next, it was observed with an electron microscope (S-3500N scanning electron microscope manufactured by Hitachi, Ltd.), 30 undivided filaments were selected from the obtained cross-sectional image, the cross-sectional area was calculated, and the average value thereof was calculated. The fineness of the undivided filament was obtained, and the fineness of the divided fiber was calculated by the following formula using the division ratio.

Fineness of split fibers = unsplit filament fineness / (total number of segments x split ratio / 100)

(3) Flexibility (45 ° cantilever method)
In accordance with JIS L1096 (6.19.1 A method paragraph), the temperature is 20 ± 2 ° C. and the humidity is 65 ± 2% in a temperature-controlled room specified in JIS Z 8703 (standard state of test place). Five test pieces are collected in each of the flow direction (MD) and the horizontal direction (CD), and the short side of the test piece is placed on a smooth horizontal table with a 45 ° slope so that the short side of the test piece matches the scale base line. Next, the test piece is manually slid gently in the direction of the slope, and when the central point of one end of the test piece comes into contact with the slope, the moving length of the other end is read on the scale. Bending softness (bending softness) is indicated by the length (mm) of the test piece moved, measured for each of the five front and back sides, and expressed as an average value in each of the flow direction (MD) and the transverse direction (CD).

  It is judged that the lower the bending resistance is, the more flexible the nonwoven fabric is. In general, it is judged that the flexibility is good when the value of the bending resistance is 50 mm or less in both the flow direction (MD) and the transverse direction (CD). However, since the required flexibility varies depending on the purpose of use, it is not necessarily limited to this value.

(4) Tensile strength In accordance with JIS L1906 (6.12.1 A method), the direction of flow in a temperature-controlled room with a temperature of 20 ± 2 ° C and a humidity of 65 ± 2% as specified in JIS Z8703 (standard state of test place) Three non-woven fabric test pieces of 25 cm in (MD) and 2.5 cm in the transverse direction (CD) were collected, and a tensile tester (Instron 5564 manufactured by Instron Japan Company Limited) under the conditions of 200 mm between chucks and a pulling speed of 200 mm / min. A tensile test was conducted using a mold, the tensile load was measured for three test pieces, and the average value of the maximum values was taken as the tensile strength.

(5) Lint-free properties As a pre-treatment for removing adhering atmospheric dust, etc., a non-ionic surfactant is used at 60 ° C in a clean room of ISO class 5 (FDIS 14644-1, 1997). It is washed by stirring with high-temperature water (15 liters per kg of nonwoven fabric). Hot water is water that has been generated in advance by reverse osmosis treatment and has a conductivity of 4 to 6 microohms / cm. Subsequently, it was sufficiently washed with water having a specific resistance value of 15 MΩ · cm or more (10 liters per kg of nonwoven fabric), dried at 70 ° C. for 40 minutes, and packed.

  After this, in accordance with JIS-B-9923 (tumbling method), a tumbling dust generation tester (CW-HDT-102, manufactured by Akachi Seisakusho) installed in an ISO class 5 clean room (FDIS 14644-1, 1997) Was run dry and it was confirmed that the inside of the testing machine was dust-free. Thereafter, the packed 25 cm × 25 cm test pieces were opened, 10 test pieces were put into the drum, and the drum was rotated at 46 rpm. Using a particle counter (manufactured by Met One A2400B Hach Ultra Analytics) for 1 minute at a suction speed of 1 cubic foot / minute, and measuring particles (particles) in the atmosphere inside the tester 30 seconds after the start of operation of the tester did. The measured value was evaluated as the number of particles per cubic foot. This suction operation was continuously performed and measurement was performed 5 times in total. Of the five measured values, the remaining measured values (for three times) were evaluated except when the total count was the maximum value and the minimum value. In the evaluation method, the number of particles of 25 μm or less was classified for each particle size, and an average value (three times) was obtained. It was judged that the smaller the number of particles (particles), the fewer the particles generated from the nonwoven fabric, and the better the lint-free property.

(6) Analysis of fiber structure [confirmation of presence / absence of crystal / amorphous]
Using a wide-angle X-ray device (RINT2500, manufactured by Rigaku Corporation, attached device: rotating sample stage, X-ray source: CuKα, output: 50 kV, 300 mA, detector: scintillation counter), an aluminum thin film is placed in front of the sample on the optical system. The sample was weighed so that the sample weight would always be 0.2 g, packed in a filling holder, irradiated with X-rays to the entire sample, and measured from the wide-angle X-ray diffraction profile measured by rotating the holder. Crystallinity was evaluated.
(A) Confirmation of crystals of propylene homopolymer and propylene / ethylene copolymer part:
2θ: A case where a broad peak was observed in the vicinity of 15 ° and 22 ° was regarded as a smectic crystal, and a case where a peak was observed in all 2θ: 14 °, 17 °, 18 ° and 21 ° was regarded as an α crystal.
(B) Confirmation of polylactic acid polymer part crystals:
2θ: crystalline when peaks are observed around 16 ° and 18 °,
A case where no peak was observed in the region was regarded as amorphous.
(C) Confirmation of polyethylene terephthalate crystal:
2θ: crystalline when peaks are observed around 17 °, 18 ° and 26 °,
A case where no peak was observed in the region was regarded as amorphous.

(Evaluation of orientation)
Using a wide-angle X-ray diffractometer (RINT2550, manufactured by Rigaku Corporation, attached device: fiber sample stage, X-ray source: CuKα, output: 40 kV 370 mA, detector: scintillation counter), the sample is aligned in the fiber axis direction and fixed to the sample holder. And an azimuth distribution curve obtained by measuring the azimuth distribution strength of the crystal plane peak [polypropylene polymer part: (110)] plane, polylactic acid polymer part: (110) plane and (200) plane). In (X-ray interference diagram), the degree of orientation in the fiber axis direction (c-axis orientation degree) was calculated from the half-value width (α) of the peak according to the following formula and evaluated. When the degree of orientation obtained by the following formula was less than 0.8, it was judged that the orientation was very low and no orientation was made.

Degree of orientation (F) = (180 ° −α) / 180 °
(Α is the peak half-value width in the azimuth distribution curve)

[Evaluation of crystallinity]
Evaluation of the crystallinity of the polylactic acid polymer part was performed as follows. The diffraction profile 2θ = 5 ° and 35 ° is connected by a straight line to be a base line. Let I be the total intensity after removing the diffraction profile below the baseline. Next, the peaks around 2θ = 16 ° and 18 ° are used as polylactic acid polymer part peaks, and the polypropylene polymer smectic crystal peak and the polylactic acid polymer part peak valley are connected by tangent lines to separate the polylactic acid polymer part peaks. The combined intensity of both peaks is I ₀ . The polylactic acid polymer crystallinity index value is obtained from the following formula.

Polylactic acid polymer crystallinity index value = I ₀ / I × 100

When the crystallinity index value was less than 1, it was assumed to be amorphous.

Example 1
Poly (L) lactic acid polymer having a weight average molecular weight Mw of 117,000, a load of 2160 g and a MFR of 190 g at 190 ° C. (trade name: LACEAH-900, L-lactic acid, manufactured by Mitsui Chemicals, Inc.) / D-lactic acid (copolymerization ratio) = 98.5 / 1.5 mol%, melting point (Tme); 165 ° C.] as polyolefin (B), propylene / ethylene having a load of 2160 g and an MFR of 230 ° C. of 60 g / 10 min. A random copolymer (Mw / Mn = 2.4, melting point (Tmo); 143 ° C., ethylene content; 4 mol%) was used, and the molding temperature of the poly-L-lactic acid-based polymer was set to 190 ° C. and a separate extruder, respectively. As shown in FIG. 1A, the molding temperature of the propylene / ethylene random copolymer is melted at 200 ° C., air at 25 ° C. is used as the cooling fluid, and the total number of segments is 16. A split type composite fiber having a weight ratio of 50/50 of polyester (A) to polyolefin (B) is converted to polyester (A) and polyolefin by a spunbond method using a split type composite fiber spinning die having a simple cross-sectional shape. Spinning was performed at a single-hole discharge rate of 1.2 g / min and a yarn speed of 2500 m / min as the total amount of (B), and was deposited on the collection belt. Next, a nozzle with a hole diameter of 0.11 mm is used to divide the fibers, the distance from the nozzle to the nonwoven fabric is 10 cm, water jet processing is performed on the nonwoven fabric surface and back surface at a water pressure of 60 kgf / cm ² and a line speed of 5 m / min. The split fiber nonwoven fabric having a basis weight of 50 g / m ² was prepared by applying once. About the obtained nonwoven fabric, the division ratio, fineness, bending resistance, tensile strength, lint-free property, and fiber structure were measured and evaluated. The results are shown in Table 1.

Example 2
Poly (L) lactic acid polymer having a weight average molecular weight Mw of 117,000, a load of 2160 g and a MFR of 190 g at 190 ° C. (trade name: LACEAH-900, L-lactic acid, manufactured by Mitsui Chemicals, Inc.) / D-lactic acid (copolymerization ratio) = 98.5 / 1.5 mol%, melting point (Tme); 165 ° C.] as polyolefin (B) with a load of 2160 g and an MFR at 230 ° C. of 60 g / 10 min. Using an ethylene random copolymer (Mw / Mn; 2.4, melting point (Tmo); 143 ° C., ethylene content; 4 mol%), the molding temperature of the poly-L-lactic acid polymer was set to 190 ° C. with separate extruders. 1 and FIG. 1A in which the molding temperature of the propylene / ethylene random copolymer is melted at 200 ° C., air at 25 ° C. is used as a cooling fluid, and the total number of segments is 16. A split type composite fiber having a weight ratio of 50/50 of polyester (A) to polyolefin (B) is converted to polyester (A) and polyolefin by a spunbond method using a split type composite fiber spinning base having such a cross-sectional shape. Spinning was performed at a single-hole discharge rate of 1.2 g / min and a yarn speed of 1500 m / min as the total amount of (B), and was deposited on a collecting belt. Next, a nozzle with a hole diameter of 0.11 mm is used to divide the fibers, the distance from the nozzle to the nonwoven fabric is 10 cm, water jet processing is performed on the nonwoven fabric surface and back surface at a water pressure of 60 kgf / cm ² and a line speed of 5 m / min. The split fiber nonwoven fabric having a basis weight of 50 g / m ² was prepared by applying once. About the obtained nonwoven fabric, the division ratio, fineness, bending resistance, tensile strength, lint-free property, and fiber structure were measured and evaluated. The results are shown in Table 1.

Comparative Example 1
Poly (L) lactic acid polymer having a weight average molecular weight Mw of 117,000, a load of 2160 g and a MFR of 190 g at 190 ° C. (trade name: LACEAH-900, L-lactic acid, manufactured by Mitsui Chemicals, Inc.) / D-lactic acid (copolymerization ratio) = 98.5 / 1.5 mol%, melting point (Tme); 165 ° C.] as polyolefin (B), propylene alone with a load of 2160 g and MFR at 230 ° C. of 60 g / 10 min Using a polymer [Mw / Mn; 2.75, melting point (Tmo); 163 ° C.], the molding temperature of the poly-L-lactic acid polymer is 190 ° C., and the molding temperature of the propylene homopolymer is 200 using separate extruders. Using a split type composite fiber spinning die having a cross-sectional shape as shown in FIG. A split type composite fiber having a weight ratio of reolefin (B) of 50/50 is a single hole discharge rate of 1.2 g / min and a yarn speed of 2500 m / min as a total amount of polyester (A) and polyolefin (B). Spinned and deposited on collection belt. Next, a nozzle having a hole diameter of 0.11 mm is used to divide the fiber, the distance from the nozzle to the nonwoven fabric is 10 cm, water jet processing is performed on the nonwoven fabric surface at a water pressure of 60 kgf / cm ² and a line speed of 5 m / 5 m / min. The split fiber nonwoven fabric having a basis weight of 50 g / m ² was prepared by applying once to the back surface. About the obtained nonwoven fabric, the division ratio, fineness, bending resistance, tensile strength, lint-free property, and fiber structure were measured and evaluated. The results are shown in Table 1.

Comparative Example 2
Polyester (A) with polyethylene terephthalate having an intrinsic viscosity of 0.77 (Mitsui Chemicals, trade name: Mitsui PET, melting point (Tme); 258 ° C.) and polyolefin (B) with a load of 2160 g at 230 ° C. Propylene homopolymer with MFR of 15 g / 10 min [Mw / Mn; 3.0, melting point (Tmo); 163 ° C.], melted in separate extruders, and molding temperature of polyethylene terephthalate in separate extruders Is melted at 310 ° C. and the molding temperature of the propylene homopolymer is 270 ° C., and a split-type composite fiber spinning die having a cross-sectional shape as shown in FIG. Thus, a split-type composite fiber in which the weight ratio of the polyester (A) to the polyolefin (B) is 50/50 is converted into a polyester (A) and a polyol. The single-hole discharge rate of the total amount 1.2 g / min fins (B), and spun at yarn speed 2500 m / min, was deposited on the collection belt. Next, using a nozzle with a hole diameter of 0.11 mm for fiber splitting, the distance from the nozzle to the nonwoven fabric is 10 cm, water jet processing is performed on the nonwoven fabric surface and back surface at a water pressure of 100 kgf / cm ² and a line speed of 5 m / min. This was performed four times, and a split fiber nonwoven fabric having a basis weight of 50 g / m ² was produced. About the obtained nonwoven fabric, the division ratio, fineness, bending resistance, tensile strength, lint-free property, and fiber structure were measured and evaluated. The results are shown in Table 1.

As is clear from Table 1, the composite fibers (Examples 1 and 2) in which the polyester (polylactic acid polymer) portion is oriented and crystallized can be easily divided into 90% or more by the water jet process, and thus obtained. The fineness of the split fibers to be obtained is also thin and excellent in flexibility, and the split fiber nonwoven fabric is lint-free (Example 1: number of particles; 1940 / ft ³ , Example 2: number of particles; 2856 / ft ³ ). Very good. Moreover, it is clear from the comparison between Example 1 and Example 2 that the lint-free property increases as the degree of orientation and crystallinity of the polyester (polylactic acid polymer) part increases.

On the other hand, the split fiber (Comparative Example 1) in which the polyester (polylactic acid polymer) portion is non-oriented and has low crystallinity is excellent in splitting property, but lint-free (Comparative Example 1: number of particles: 4939) / Ft ³ ) and clearly inferior to the examples.

In addition, the split fibers having a large melting point difference of 101 ° C. between the polyester part and the polyolefin part need to be subjected to water jet processing four times each on the front and back surfaces of the nonwoven fabric in order to improve the split ability (Comparative Example 2). Although the fineness of the resulting split fibers was reduced, the flexibility was inferior, and the lint-free property was also inferior (number of particles: 5699 / ft ³ ).

  The split-type composite fiber nonwoven fabric that can be obtained by the method for manufacturing a split fiber nonwoven fabric of the present invention has flexibility and hardly loses fibers when it is used for applications where the nonwoven fabric surface is rubbed, such as clothing or wiping cloth. For this reason, as articles used in clean rooms when manufacturing electronic products such as semiconductor integrated circuits and display products, optical products, etc., that is, as materials for clean room clothing, masks, wiping cloths, etc. It can be particularly preferably used.

In addition, because it has high lint-free properties, it can be used for other purposes besides clean room use, such as various wiping cloths, non-woven fabrics for clothing such as surgical gowns, medical gowns and industrial gowns, packaging fabrics, It can also be widely used for surface materials of sanitary materials such as disposable diapers and napkins, bedding such as bed sheets and pillow covers, carpets and base fabrics for artificial leather.
Other applications include VTR and compact disc cleaning cloth, disc polishing, filter cloth, general consumer materials such as glass, precious metals, high-quality items, window glass, OA equipment, automobile windows, musical instruments, mirrors, etc. Examples include dirt removal, oil film removal, flooring, and toilet cleaners.

FIG. 1 is a schematic view showing an example of a cross section of a conjugate fiber according to the present invention.

      The five forms (a) to (d) were listed. (E) is an example of the cross-sectional form after a division | segmentation process.

In the figure, the white and black portions represent the resins to be combined.

Claims (14)

  A composite fiber comprising a polyester (A) part and a polyolefin (B) part in contact with each other, wherein the polyester (A) part is oriented and crystallized.   The polyester (A) having a melting point difference between the polyester (A) and the polyolefin (B) [the melting point (Tme) of the polyester (A) −the melting point (Tmo) of the polyolefin (B)] in the range of less than 5 to 30 ° C. The composite fiber according to claim 1, wherein the polyolefin (B) is used.   The composite fiber according to claim 1 or 2, wherein the polyester (A) part and the polyolefin (B) part have a property of being divided.   The composite fiber according to any one of claims 1 to 3, wherein the polyester (A) is a polylactic acid polymer.   The composite fiber according to any one of claims 1 to 3, wherein the polyolefin (B) is a propylene / α-olefin random copolymer.   A nonwoven fabric comprising the conjugate fiber according to any one of claims 1 to 5.   A split fiber nonwoven fabric obtained by dividing a polyester (A) portion and a polyolefin (B) portion of a composite fiber by applying stress to the nonwoven fabric according to claim 6.   The split fiber nonwoven fabric according to claim 7, wherein the stress is due to a high-pressure liquid flow.   The split fiber nonwoven fabric according to claim 7 or 8, wherein the fineness of the split fibers is in the range of 0.001 to 2.0 denier.   The polyester (A) having a melting point difference between the polyester (A) and the polyolefin (B) [the melting point (Tme) of the polyester (A) −the melting point (Tmo) of the polyolefin (B)] in the range of less than 5 to 30 ° C. Polyolefin (B) is discharged from a spinneret having a composite spinning nozzle, and the spun composite fiber is cooled by a cooling fluid, and tension is applied to the fiber to make the polyester (A) thin. A method for producing a nonwoven fabric comprising a composite fiber, characterized in that after orientation crystallization, the crystal is collected and deposited on a collection belt.   The manufacturing method of the split fiber nonwoven fabric characterized by dividing | segmenting the polyester (A) part and polyolefin (B) part of a composite fiber by adding stress to the nonwoven fabric consisting of the composite fiber of Claim 10. The method for producing a split fiber nonwoven fabric according to claim 10, wherein the stress is caused by a high-pressure liquid flow.   A wiping cloth containing the split fiber nonwoven fabric according to any one of claims 7 to 9. The article for clean rooms containing the split fiber nonwoven fabric of any one of Claims 7-9.

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