JP2006063488A - High elongation superfine filament nonwoven fabric - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stably provide a high elongation superfine filament nonwoven fabric by melt-spinning polymers into conjugated filaments and then treating a nonwoven fabric composed of the conjugated filaments with water without using a chemical agent or the like. <P>SOLUTION: This method for producing the high elongation superfine filament nonwoven fabric is characterized by water-dissolving (A) a water-soluble thermoplastic polyvinyl alcohol having a saponification degree of 90 to 99.9 mol.% from a filament nonwoven fabric composed of superfine filament-formable conjugated filaments comprising (A) the polymer and (B) a polypropylene having a MFR of ≤30 or a polyethylene terephthalate-based polyester copolymerized with ≥8 mol.% of isophthalic acid. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an ultra-thin fiber nonwoven fabric having a high elongation obtained by treating a composite long-fiber nonwoven fabric composed of water-soluble thermoplastic polyvinyl alcohol and another thermoplastic polymer with water, a method for producing the same, and a method for producing the ultra-long fiber nonwoven fabric. The present invention relates to a synthetic leather and a sound absorbing material using a long-fiber nonwoven fabric.

  Conventionally, non-woven fabrics have been used in a wide range of fields including industrial materials and clothing. Among these, the long fiber nonwoven fabric obtained by the spunbond method is produced by directly forming a long fiber without passing through the short fiber, and thus has an advantage of high productivity and low cost. However, spunbonded nonwoven fabrics generally have high strength, low elongation, and high elongation modulus, so when deep drawing is performed during molding, they can partially lift or increase the volume of the molded product. There is a disadvantage that it can not.

  In addition, since the spunbond nonwoven fabric has low concealability, there are cases in which it has been necessary to use a laminated composite with another nonwoven fabric in order to improve this. For example, a method of laminating and integrating nonwoven fabrics made of ultrafine fibers is known, but these laminated nonwoven fabrics also have a high elongation modulus of spunbond nonwoven fabrics, so that the shape followability at the time of molding is poor, and the resulting molded product There is a drawback that the volume is lacking and the use is limited due to a hard texture.

Therefore, studies have been made to provide a nonwoven fabric having a higher elongation, bulkiness, and soft texture than conventional spunbonded nonwoven fabrics.
As a method for obtaining a non-woven fabric having high elongation, for example, JP-A-2004-36065 describes a method for obtaining a non-woven fabric having an elongation of 150% or more by spinning under unstretched or low-stretching conditions. Yes. However, the obtained fiber is a so-called thick fiber having a fiber diameter of 5 dtex or more, and cannot be applied to an application field in which a nonwoven fabric made of ultrafine fibers is required. Furthermore, the nonwoven fabric actually manufactured in the same publication is a short fiber nonwoven fabric, not a long fiber nonwoven fabric. In general, in the case of a short fiber non-woven fabric, the elongation at break tends to be high due to the loss of fibers, and it is highly questionable whether the same high elongation can be obtained even with a long-fiber non-woven fabric in which almost no fiber loss occurs.

  On the other hand, a fiber web made of fibers obtained by composite spinning of two kinds of polymers having different melting points is subjected to thermocompression in some places, and then expanded in the width direction of the nonwoven fabric to divide the fibers to form a stretchable ultrafine fiber nonwoven fabric sheet. Although the method of obtaining is described in JP-A-11-61621, the breaking elongation of the nonwoven fabric obtained by the method described in this publication is at most 30% in the length direction of the nonwoven fabric. It is hard to say that it is a non-woven fabric. In general, the length direction of the nonwoven fabric tends to cause fiber orientation more than the transverse direction, and as a result, the elongation in the length direction tends to be low.

  Conventionally, as a method for producing ultrafine fibers, a method of dissolving and removing at least one component of a multicomponent fiber with an organic solvent to make ultrafine, or a method of decomposing and removing with an alkali to make ultrafine fibers are generally used. . However, such a method requires special equipment in view of the danger of handling chemicals and environmental pollution, and is not sufficiently satisfactory in terms of safety and hygiene of workers and manufacturing costs. In addition, since a component other than the component to be removed is undesirably affected, the combination of components constituting the composite fiber is limited, or the component to be removed must be used without being sufficiently removed. In some cases, a non-woven fabric of a certain quality could not be obtained.

  On the other hand, polyvinyl alcohol (hereinafter sometimes abbreviated as PVA) is a water-soluble polymer, and it is known that the degree of water-solubility can be changed by its basic skeleton, molecular structure, form, and various modifications. . Moreover, it has been confirmed that PVA is biodegradable. Currently, PVA and PVA fibers having such basic performance are attracting a lot of attention because how to harmonize the synthetic material with the natural world has become a major issue in terms of the global environment.

As described above, conventionally, it has been difficult to obtain an ultra-thin fiber nonwoven fabric without using chemicals that have high elongation in the length direction and are dangerous to the environment and workers.
JP 2004-36065 A JP-A-11-61621

  The object of the present invention is to enable the production of ultra-thin fiber nonwoven fabrics that have a high elongation and are treated with water without using chemicals, etc., and have excellent moldability, appearance, texture, etc. Another object is to provide a synthetic leather using the nonwoven fabric and a sound absorbing material using the nonwoven fabric.

That is, this invention is comprised from the ultra-thin fiber bundle consisting of a thermoplastic polymer, and the following requirements (a) and (b)
(A) The single fiber fineness of the ultra-fine long fibers is 0.0005 to 0.5 dtex,
(B) An ultra-fine long-fiber non-woven fabric characterized by satisfying that the breaking elongation in the length direction of the ultra-fine long-fiber non-woven fabric is 100 to 500%.
The present invention also includes the following (A) and (B)
(A) a water-soluble thermoplastic polyvinyl alcohol having a saponification degree of 90 to 99.9 mol%,
(B) Polyethylene terephthalate polyester obtained by copolymerizing polypropylene having an MFR of 30 or less or isophthalic acid having 8 mol% or more,
(A) is dissolved and removed with water from a long-fiber non-woven fabric composed of composite long fibers that can be made into ultra-fine fibers.
Furthermore, the present invention is a synthetic leather in which the ultra-thin fiber nonwoven fabric is used as a base fabric, and a sound absorbing material in which the ultra-thin fiber nonwoven fabric is used.

  According to the present invention, it is composed of water-soluble thermoplastic polyvinyl alcohol and a thermoplastic polymer, and is processed with water without using chemicals or the like by using a composite long fiber nonwoven fabric (so-called spunbond nonwoven fabric) by melt spinning. By doing so, it became possible to obtain a highly elongated and ultrafine long fiber nonwoven fabric.

  The nonwoven fabric of the present invention is a nonwoven fabric (A) composed of a thermoplastic continuous polymer (B) and a composite long fiber that can be divided in the length direction from a water-soluble thermoplastic PVA (A) having a saponification degree of 90 to 99.99 mol%. Is treated with water to dissolve and remove the water-soluble thermoplastic PVA constituting the composite long fiber, and is an extra-fine long fiber nonwoven fabric made of a thermoplastic polymer.

  The PVA (A) in the present invention includes not only PVA homopolymer but also modified PVA in which a functional group is introduced by copolymerization, terminal modification, and post-modification.

  200-800 are preferable, as for the viscosity average polymerization degree (henceforth abbreviated as polymerization degree) of PVA (A) used for this invention, 230-600 are more preferable, and 250-500 are especially preferable. When the degree of polymerization is less than 200, sufficient spinnability may not be obtained during spinning, and as a result, a satisfactory long fiber nonwoven fabric may not be obtained. On the other hand, if the degree of polymerization exceeds 800, the melt viscosity is too high to discharge the polymer from the spinning nozzle, and a satisfactory long fiber nonwoven fabric may not be obtained.

The degree of polymerization (P) of PVA is measured according to JIS-K6726. That is, after the PVA is completely re-saponified and purified, the intrinsic viscosity [η] (dl / g) measured in water at 30 ° C. is obtained by the following formula.
P = ([η] × 10 ³ /8.29) ^{(1 / 0.62)}

  The saponification degree of PVA (A) used in the present invention is 90 to 99.99 mol%, preferably 92 to 99.98 mol%, more preferably 94 to 99.96 mol%, and 95 to 99.95 mol%. % Is particularly preferred. When the degree of saponification is less than 90 mol%, the thermal stability of PVA is poor, and satisfactory composite melt spinning cannot be performed by thermal decomposition or gelation, and the composite long fiber nonwoven fabric of the present invention directly connected to melt spinning is also available. Can not. On the other hand, PVA having a saponification degree larger than 99.99 mol% is difficult to produce stably.

  PVA is obtained by saponifying the vinyl ester unit of the vinyl ester polymer. Vinyl compound monomers for forming vinyl ester units include vinyl formate, vinyl acetate, vinyl propionate, vinyl valenate, vinyl caprate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl pivalate and Examples thereof include vinyl versatate, and among these, vinyl acetate is preferable from the viewpoint of obtaining PVA.

  The PVA (A), which is one component constituting the composite long-fiber nonwoven fabric of the present invention, may be a homopolymer or a modified PVA introduced with copolymerized units, but it is a composite melt-spinnable, hydrophilic, fiber From the viewpoint of the physical properties of the nonwoven fabric, it is preferable to use modified PVA into which copolymer units are introduced. Examples of the comonomer include various types. For example, α-olefins such as ethylene, propylene, 1-butene, isobutene, and 1-hexene, methyl vinyl ether are easily available. , Vinyl ethers such as ethyl vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, n-butyl vinyl ether, etc., vinyl ethers containing hydroxy groups such as ethylene glycol vinyl ether, 1,3-propanediol vinyl ether, 1,4-butanediol vinyl ether Allyl ethers such as allyl acetate, propyl allyl ether, butyl allyl ether, hexyl allyl ether, N-vinylamides such as N-vinylformamide, N-vinylacetamide, N-vinylpyrrolidone, oxy Monomers having a lucylene group, 3-buten-1-ol, 4-penten-1-ol, 5-hexen-1-ol, 7-octen-1-ol, 9-decen-1-ol, 3- Monomers derived from hydroxy group-containing α-olefins such as methyl-3-buten-1-ol are preferred.

Particularly, from the viewpoints of copolymerizability, melt spinnability, fiber properties, etc., ethylene, propylene, 1-butene, α-olefins having 4 or less carbon atoms of isobutene, methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, i-propyl Vinyl ethers such as vinyl ether and n-butyl vinyl ether are more preferable. The units derived from α-olefins having 4 or less carbon atoms and vinyl ethers are preferably present in the PVA in an amount of 0.1 to 15 mol%, more preferably 2 to 13 mol%.
Furthermore, it is particularly preferable to use a modified PVA into which ethylene has been introduced as an α-olefin because the fiber properties are improved. As content of an ethylene unit, 3-15 mol% is preferable and 5-13 mol% is more preferable.

  Examples of the PVA used in the present invention include known methods such as bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization. Among them, a bulk polymerization method or a solution polymerization method in which polymerization is performed without solvent or in a solvent such as alcohol is usually employed. Examples of alcohol used as a solvent during solution polymerization include lower alcohols such as methyl alcohol, ethyl alcohol, and propyl alcohol. Initiators used for copolymerization include α, α′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethyl-valeronitrile), benzoyl peroxide, n-propyl peroxycarbonate And known initiators such as azo initiators or peroxide initiators. Although there is no restriction | limiting in particular about superposition | polymerization temperature, The range of 0 to 200 degreeC is suitable.

  As for the content rate of the alkali metal ion in PVA (A) used by this invention, 0.0001-0.05 mass part is preferable in conversion of sodium ion with respect to 100 mass parts of PVA (C), 0.0001-0. 03 parts by mass are more preferable, and 0.0002 to 0.01 parts by mass are particularly preferable. If the content of alkali metal ions is less than 0.0001 parts by mass, it is difficult to produce industrially. Further, when the content of alkali metal ions is more than 0.05 parts by mass, decomposition, gelation and yarn breakage during composite melt spinning are remarkable, and there are cases where stable fiberization cannot be achieved. Examples of the alkali metal ion include potassium ion and sodium ion.

In the present invention, the method of containing a specific amount of alkali metal ions in PVA is not particularly limited, and a method of adding a compound containing alkali metal ions after polymerizing PVA, saponifying a vinyl ester polymer in a solvent. In this case, by using an alkaline substance containing alkali ions as a saponification catalyst, alkali metal ions are blended into PVA, and the PVA obtained by saponification is washed with a washing solution, whereby alkali metal ions contained in PVA are obtained. Although the method of controlling content etc. is mentioned, the latter is more preferable.
The content of alkali metal ions can be determined by atomic absorption method.

  Examples of the alkaline substance used as the saponification catalyst include potassium hydroxide and sodium hydroxide. The molar ratio of the alkaline substance used for the saponification catalyst is preferably from 0.004 to 0.5, particularly preferably from 0.005 to 0.05, based on the vinyl acetate unit. The saponification catalyst may be added all at the beginning of the saponification reaction, or may be added additionally during the saponification reaction. Examples of the saponification solvent include methanol, methyl acetate, dimethyl sulfoxide, dimethylformamide and the like. Among these solvents, methanol is preferable, methanol whose water content is controlled to 0.001 to 1% by mass is more preferable, methanol whose water content is controlled to 0.003 to 0.9% by mass is more preferable, and water content is Methanol controlled to 0.005 to 0.8% by mass is particularly preferable.

Examples of the cleaning liquid include methanol, acetone, methyl acetate, ethyl acetate, hexane, water, and the like. Among these, methanol, methyl acetate, water alone or a mixed liquid is more preferable.
Although it sets so that the content rate of an alkali metal ion may be satisfied as a quantity of a washing | cleaning liquid, 300-10000 mass parts is preferable with respect to 100 mass parts of PVA normally, and 500-5000 mass parts is more preferable. As washing | cleaning temperature, 5-80 degreeC is preferable and 20-70 degreeC is more preferable. The washing time is preferably 20 minutes to 100 hours, more preferably 1 hour to 50 hours.

In the PVA (A) used in the present invention, the content ratio of the acid having an acid group having a pKa at 25 ° C. of 5.0 or less is preferably such that α shown below is 0.01 to 1, 0.8 is more preferable, and 0.05 to 0.6 is particularly preferable. In the present invention, the acid content in the formula of α shown below means the value obtained by neutralization titration converted to acetic acid. pKa is defined by pKa = −logKa, where Ka is the dissociation constant of the acid. When an acid having an acid group with a pKa of more than 5.0 is used, and when the acid content ratio is different from 0.01 to 1 as α shown below, PVA decomposition, gelation and There is a case where the yarn is severely broken and cannot be stably fiberized. Examples of acids having an acid group with a pKa at 25 ° C. of 5.0 or less include acetic acid, phosphoric acid, and sodium monophosphate.
α = Acid content in polyvinyl alcohol (mass%) / Alkali metal ion content in polyvinyl alcohol (mass%)

  In the present invention, the method for containing a specific amount of an acid having an acid group with a pKa of 5.0 or less at 25 ° C. in the PVA is not particularly limited, and after saponifying a vinyl ester polymer in a solvent, the pKa is 5 A method for controlling the acid content contained in PVA by blending the acid in PVA by using an acid having an acid group of 0.0 or less and washing the PVA obtained by saponification with a washing solution And a method of containing a specific amount of acid by treating the dried PVA with a solvent containing an acid, a method of adding a specific amount of acid when preparing PVA pellets, and the like. In addition, acid content can be calculated | required by carrying out the neutralization titration of the methanol extraction part from PVA with sodium hydroxide aqueous solution.

  Further, a plasticizer can be added to PVA for the purpose of adjusting the melting point and the melt viscosity within a range that does not impair the purpose and effect of the present invention. As the plasticizer, conventionally known ones can be used, but diglycerin, polyglycerin alkyl monocarboxylic acid esters, glycols having ethylene oxide and propylene oxide added, and the like are preferably used. Among these, the compound which added 1-30 mol% of ethylene oxide with respect to 1 mol of sorbitol is preferable.

  The PVA used in the present invention has biodegradability and is decomposed into water and carbon dioxide when activated sludge treatment or buried in soil. The activated sludge method is preferable for the treatment of the waste liquid after dissolving PVA. When the PVA aqueous solution is continuously treated with activated sludge, it is decomposed in 2 days to 1 month. Moreover, since PVA used for this invention has low combustion heat and the load with respect to an incinerator is small, you may incinerate PVA by drying the waste_water | drain which melt | dissolved PVA.

Examples of the thermoplastic polymer (hereinafter also referred to as B) that constitutes the composite fiber in the present invention include polyolefins such as polypropylene, polyethylene, polybutene, polymethylpentene, and copolymers thereof. , Aromatic polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyhexamethylene terephthalate, polylactic acid, polyethylene succinate, polybutylene succinate, polybutylene succinate adipate, polyhydroxybutyrate-polyhydroxyvalylate copolymer, poly Aliphatic polyesters such as caprolactone and copolymers thereof, nylon 6, nylon 66, nylon 10, nylon 12, nylon 6-12 and other aliphatic polyamides and copolymers thereof, 2 ethylene units At least one of ethylene-vinyl alcohol copolymer, polystyrene, polydiene, chlorine, polyolefin, polyester, polyurethane, polyamide, fluorine elastomer, etc. containing 0 mol% to 70 mol% However, polyolefins, polyesters and polyamides are preferred from the viewpoint of easy composite spinning with PVA (A) used in the present invention, and polyolefins, particularly polypropylene, from the viewpoint of easy availability and processability. Is more preferable.
Of course, two or more thermoplastic polymers may be used as the thermoplastic polymer (B).

  In the case of using polypropylene for the thermoplastic polymer (B), a high MFR polypropylene having a low melt viscosity is effective for stable composite spinning, but the present inventors can obtain a higher MFR value of polypropylene. It has been found that ultra-thin fiber nonwoven fabrics tend to have a low elongation. That is, the non-woven fabric of high elongation targeted by the present invention can be obtained for the first time using a polypropylene having an MFR of 30 or less, preferably by using a polypropylene having an MFR value of 28 or less, more preferably an MFR value of 25 or less. The elongation of is further improved. However, if the MFR value is too low, spinning becomes difficult, so the lower limit value of the MFR value is 5.0 as a guide. The MFR value can be in the above range by mixing two types of polypropylene. In addition, there is no problem in blending other polymers with polypropylene as long as the elongation at break does not deviate from the range defined in the present invention.

  Further, when polyester is used as the thermoplastic polymer (B), in order to obtain a high elongation ultrafine fiber nonwoven fabric of the present invention, polyethylene terephthalate copolymerized with 8 mol% or more of isophthalic acid is used. It has been found that it is necessary to use it. More preferred is a polyethylene terephthalate polyester copolymerized with 9 mol% or more of isophthalic acid. In this case, the elongation of the resulting nonwoven fabric is further improved. However, if the copolymerization ratio is too high, the fiber physical properties are lowered. Therefore, the copolymerization ratio of isophthalic acid is preferably 30 mol% or less, more preferably 20 mol% or less. In the present invention, when polyester is used, copolymer monomer units other than isophthalic acid may be present as long as the elongation at break does not deviate from the range defined in the present invention. Further, polyethylene terephthalate can be blended with other polymers as long as the elongation at break does not deviate from the range defined in the present invention.

  The mass ratio of (B) and (A) of the composite continuous fiber nonwoven fabric composed of the thermoplastic polymer (B) and PVA (A) used in the present invention is 5/95 to 95/5, and 10/90 to 90 / 10 is more preferable. If it is out of the preferred range, the combined effect may not appear.

  Further, as long as the purpose and effect of the present invention are not impaired, the thermoplastic PVA (A) and the thermoplastic polymer (B) may include a stabilizer such as a copper compound, a colorant, an ultraviolet absorber, a light as necessary. Stabilizers, antioxidants, antistatic agents, flame retardants, plasticizers, lubricants, crystallization rate retarders can be added during the polymerization reaction or in subsequent steps. Addition of an organic stabilizer such as hindered phenol, a copper halide compound such as copper iodide, and an alkali metal halide compound such as potassium iodide as heat stabilizers improves the melt retention stability during fiberization. Therefore, it is preferable.

  If necessary, fine particles having an average particle size of 0.01 μm or more and 5 μm or less can be added in an amount of 0.05% by mass or more and 10% by mass or less during the polymerization reaction or in a subsequent step. The type of fine particles is not particularly limited, and for example, inert fine particles such as silica alumina, titanium oxide, calcium carbonate, and barium sulfate can be added, and these may be used alone or in combination of two or more. In particular, inorganic fine particles having an average particle size of 0.02 μm or more and 1 μm or less are preferable, and spinnability and stretchability are improved.

  Next, the manufacturing method of the composite nonwoven fabric comprised by the long fiber which consists of the thermoplastic polymer (B) and PVA (A) used for this invention is demonstrated. The composite nonwoven fabric composed of the long fibers of the present invention can be efficiently produced by a method for producing a so-called spunbond nonwoven fabric that is directly coupled to melt spinning.

  For example, the thermoplastic polymer (B) and the PVA (A) are melt-kneaded with separate extruders, and then each molten polymer stream is guided to the spinning head, and the flow rate is measured and merged from the spinning nozzle hole. After discharging and cooling the discharged yarn with a cooling device, using a suction device such as an air jet nozzle, the yarn is taken up at a speed of 1000 to 6000 m / min so as to achieve the desired fineness. After pulling and pulverizing with high-speed airflow at the appropriate speed, it is deposited on the movable collection surface while opening the fiber to form a nonwoven web, and then this web is partially crimped and wound to form a composite length A fiber nonwoven fabric can be obtained. At this time, in consideration of the elongation of the obtained ultra-thin long fiber nonwoven fabric, it is preferable to set the take-up speed lower than that of 1000 to 3000 m / min.

  As the composite cross section of the composite long fiber constituting the composite long fiber nonwoven fabric of the present invention, the splitting property and the uniformity of the ultrafine fibers after the division, the nonwoven fabric, the synthetic leather using the nonwoven fabric, and the sound absorbing material using the nonwoven fabric When considering the quality, physical properties, etc., the split component has a wedge-shaped or fan-shaped radial split composite fiber, the multi-layer laminated split composite fiber has a strip-shaped split component, and a plurality of split composite fibers in the matrix Those having a sea-island type composite fiber having a shape in which the divided components are dispersed are preferred. When the cross-sectional shape of the composite long fiber has a mandarin orange cross-sectional shape, a sector shape, or a bonded shape, the ultrafine fiber forming part (B) constituting the composite fiber is made of water-soluble thermoplastic PVA (A). It is preferable from the point of productivity that it is divided | segmented into 2-20 pieces. Further, when the composite cross-sectional shape is a sea-island type, (B) constitutes an island component, (A) constitutes a sea component, and the number of islands in the range of 2 to 800 is preferable in terms of productivity.

In the present invention, the fiberizing conditions constituting the composite long-fiber nonwoven fabric need to be appropriately set according to the combination of the polymers and the composite cross section, but mainly determine the fiberizing conditions while paying attention to the following points. It is desirable.
The spinneret temperature is preferably (Mp + 10) ° C. to (Mp + 80) ° C. when the melting point of a polymer having a high melting point among the polymers constituting the composite long fiber is Mp, and the shear rate (γ) is 500 to 25000 sec ^−1. Spinning with a draft (V) of 50 to 2000 is preferred. Also, from the viewpoint of spinning stability, it is preferable to perform composite spinning by combining polymers having close melt viscosities as measured by the die temperature at the time of spinning and the shear rate at the time of passing through the nozzle when viewed from the combination of the polymers to be combined. .

The melting point Tm of PVA in the present invention is the peak temperature of the main endothermic peak observed with a differential scanning calorimeter (DSC: for example, TA3000, TA3000). The shear rate (γ) is calculated as γ = 4Q / πr ³ where r (cm) is the nozzle radius and Q (cm ³ / sec) is the amount of polymer discharged per single hole. The draft V is calculated by V = 5 A · πr ² / 3Q when the take-up speed is A (m / min).

When producing the conjugate fiber of the present invention, at a temperature lower than the melting point Mp + 10 ° C. of the polymer having a high melting point among the polymers constituting the conjugate long fiber, the melt viscosity of the polymer is too high, and the It is inferior in stringing and thinning properties, and when it exceeds Mp + 80 ° C., PVA tends to be thermally decomposed, so that stable spinning cannot be performed. Further, the shear rate is easily Dan'ito lower than 500 sec ^-1, spinnability becomes high back pressure of the nozzle and higher than 25000Sec ^-1 deteriorates. When the draft is lower than 50, unevenness in fineness becomes large and stable spinning is difficult, and when the draft is higher than 2000, the yarn is easily broken.

  In the present invention, when the discharged yarn is pulled and thinned using a suction device such as an air jet nozzle, it is pulled and thinned by a high-speed air stream at a speed corresponding to a yarn take-up speed of 1000 to 6000 m / min. It is preferable to make it. Furthermore, when taking into consideration the elongation of the obtained ultra-thin long fiber nonwoven fabric, it is more preferable to set the take-up speed to 1000 to 3000 m / min. The conditions for taking up the yarn by the suction device are appropriately selected depending on the melt viscosity of the molten polymer discharged from the spinning nozzle hole, the discharge speed, the spinning nozzle temperature, the cooling conditions, etc., but if it is less than 1000 m / min, the cooling of the discharged yarn is performed. Adhesion between adjacent yarns may occur due to delay in solidification, and the orientation / crystallization of the yarn does not progress, and the resulting composite nonwoven fabric is undesirably coarse and low in mechanical strength. On the other hand, if it exceeds 3000 m / min, sufficient elongation may not be imparted to the resulting non-woven fabric. If it exceeds 6000 m / min, the warp / thinning property of the discharged yarn cannot be followed and the yarn Cutting occurs, and a stable composite long fiber nonwoven fabric cannot be produced.

  Furthermore, when stably producing the PVA composite long fiber nonwoven fabric of the present invention, the distance between the spinning nozzle hole and the suction device such as an air jet nozzle is preferably 30 to 200 cm. The spacing depends on the polymer used, the composition, and the spinning conditions described above, but if the spacing is less than 30 cm, fusion between adjacent yarns may occur due to a delay in cooling and solidification of the discharged yarn. In addition, since the orientation and crystallization of the yarn does not proceed, the resulting composite nonwoven fabric is undesirably rough and low in mechanical strength. On the other hand, when the length exceeds 2000 cm, cooling and solidification of the discharged yarn progresses too much, so that the discharged yarn cannot follow the stringing / thinning property, and the yarn is cut, thereby producing a stable composite long fiber nonwoven fabric. I can't. In the present invention, the thickness of the composite long fiber is preferably in the range of 0.5 to 10 dtex from the viewpoint of physical properties of the nonwoven fabric obtained after extraction and production conditions.

  In the present invention, it is important to produce an extremely long fiber nonwoven fabric of the thermoplastic polymer (B) by dissolving and removing PVA (A) from the composite long fiber nonwoven fabric with water. There is no particular limitation on the method of water extraction of PVA (A) from the composite long-fiber nonwoven fabric, and any method such as a method of processing in hot water such as a dyeing machine or a method of injecting a high-pressure water flow like the water jet method can be used. It can be selected appropriately. The extraction water may be neutral, and may be an alkaline aqueous solution, an acidic aqueous solution, or an aqueous solution to which a surfactant or the like is added. The extraction processing temperature may be appropriately adjusted according to the purpose, but the processing time becomes shorter as the processing temperature is higher. When extracting using hot water, it is preferable to process at 50 degreeC or more, and it is especially preferable to perform an extraction process at 80 degreeC or more. Further, the water jet method is a very effective method in that joining between the divided ultra-thin fibers is possible simultaneously with the dissolution and removal of PVA.

  In the present invention, each of the ultra long fibers of the thermoplastic polymer (B) obtained by dissolving and removing PVA (A) from the composite long fiber nonwoven fabric with water has a fineness of 0.0005 dtex to 0.5 dtex. Is necessary, preferably has a fineness of 0.001 dtex to 0.45 dtex, more preferably has a fineness of 0.002 dtex to 0.4 dtex, and particularly preferably has a fineness of 0.005 dtex to 0.35 dtex. . When the fineness of the long fiber after ultrafinening is less than 0.0005 dtex, the fiber strength of the ultrafine fiber becomes low, and the function as a long fiber nonwoven fabric cannot be sufficiently achieved. It is not possible to produce a synthetic leather with good quality using, and a sound-absorbing material using the ultra-thin long fiber nonwoven fabric. On the other hand, when the fineness of the ultrafine fibers is larger than 0.5 dtex, the ultrafineness is not sufficient, and the flexibility and appearance of the synthetic leather are deteriorated. Further, when used as a sound absorbing material, sufficient sound absorbing performance cannot be obtained.

  In the present invention, the elongation at break in the length direction (MD direction) of the ultra-thin fiber nonwoven fabric composed of the thermoplastic polymer (B) obtained by dissolving and removing PVA (A) from the composite long-fiber nonwoven fabric with water is 100 to 500. %. The elongation is preferably 100 to 450%, and more preferably 100 to 400%. When the elongation at break in at least one direction in the length direction and the width direction is lower than 100%, the moldability becomes insufficient, and as a result, a synthetic leather having a good quality, a molded body using synthetic leather, or the nonwoven fabric is used. It may not be possible to produce a sound absorbing material or other molded body. On the other hand, when the elongation is 500% or more, the form stability is insufficient.

  Further, in the present invention, the breaking elongation in the width direction (CD direction) is also preferable for obtaining a molded product without worrying about the directionality in the vertical and horizontal directions. Specifically, the breaking elongation in the width direction is 50 to 500%. Some cases are preferable, and more preferably, the breaking elongations in the length direction and the width direction of the ultra-thin fiber nonwoven fabric are both 100 to 400%. In order to increase the breaking elongation in the width direction, the same means as the means for increasing the elongation in the length direction may be used as described above. Specifically, a method using a polypropylene having a low MFR value as a polypropylene to be used, a method using a copolymer obtained by copolymerizing isophthalic acid in an amount as described above, or the like may be used.

Generally known nonwoven fabrics are known in the art in which the elongation in the width direction of the nonwoven fabric is higher than the elongation in the length direction, and the elongation at break in the width direction exceeds 100%. There is no actual high-strength non-woven fabric having a high elongation exceeding 100%.
In the present invention, the ratio of the breaking elongation in the width direction to the breaking elongation in the length direction, that is, the CD direction breaking elongation / MD direction breaking elongation is 0.1 to 10 in terms of formability. More preferably, it is in the range of 0.4 to 2.5, most preferably 0.5 to 2.0. In general, when the conventional nonwoven fabric has a high elongation at break in the CD direction, the ratio value is high and the directionality is mainly high, but in the present invention, this value is low and isotropic. It can be said. In order to increase this ratio, the spinning speed, fiber opening property, and embossing conditions may be adjusted as appropriate.

  In the present invention, the composite long fiber nonwoven fabric and the split ultrafine fiber nonwoven fabric obtained as described above are subjected to a heat embossing method, an emulsion adhesion method, a water jet method, a needle punch method, an ultrasonic sealing method, a powder dot adhesion method, a through air A method of maintaining the form by a joining method such as a method or a stitch bond method is employed. Among these, the hot embossing method, the water jet method, and the needle punch method are particularly preferable from the viewpoints of the appearance and quality of the ultra-fine long-fiber nonwoven fabric. There is no restriction | limiting in particular about in which stage joining is performed, It is possible to implement suitably as needed. For example, it may be before water extraction of PVA (A) or after split ultrafine.

In addition, when performing thermocompression treatment such as a hot embossing method, there is no particular restriction on the treatment conditions, but the total area of the thermocompression bonding portion is preferably 30% or less with respect to the total area of the nonwoven fabric, More preferably, the content is in the range of 10 to 25% in order to satisfactorily exhibit the elongation, flexibility, and bulkiness of the nonwoven fabric. The ultra-thin fiber non-woven fabric obtained in this manner is preferable in terms of handling properties, processability, homogeneity, and non-woven fabric production conditions of the non-woven fabric in which the basis weight is in the range of 5 to 300 g / m ² .

  Furthermore, the ultra-fine long-fiber nonwoven fabric obtained in the present invention can be used not only by itself, but also laminated with a non-woven fabric produced by other methods such as homo-long-fiber nonwoven fabric, melt blown, etc. When used in the above applications, practical functions can be further imparted.

  The nonwoven fabric of the present invention can be widely used in applications where conventional nonwoven fabrics made of polypropylene, polyester and other materials are used. For example, wiper use, filter use, insulation use, battery separator use, capacitor separator use, other electronics use, oil adsorbent use, cement compounding use, rubber compounding use, various tape base materials, etc. , Medical and hygiene materials such as disposable diapers, gauze, hot tie, medical gowns and surgical tape, apparel materials, protective applications, vehicle interior materials, sound absorbing materials, heat insulating materials, agricultural materials, hygiene materials, interior Uses, Artificial leather / synthetic leather base fabric use, packaging use, printed material use, storage material use, soil stabilizer use, sand flow prevention material use, reinforcement material use, footwear use, other life and industrial use For material use.

  Especially, since the nonwoven fabric of this invention is high elongation, it is suitable for the molded member which requires high moldability. For example, it is an application used in automobile door trims, ceiling materials, seat sheets, instrument panels, automobile interior materials, shoe shoes materials, sound absorbing materials, food filter bags, insect repellent / air freshener containers, and the like.

Especially the nonwoven fabric of this invention is suitable for the base fabric of the synthetic leather which covers a curved surface or is processed for curved surfaces. Next, a method for obtaining synthetic leather using the ultra-thin fiber nonwoven fabric of the present invention as a base fabric will be described. Synthetic leather is manufactured by applying a synthetic resin typified by an elastic resin on a base fabric or impregnating the base fabric.
The synthetic resin to be used may be anything that can be integrated with an ultra-thin fiber non-woven fabric to form a flexible film or a flexible substrate layer, such as a polyvinyl chloride resin, a polyolefin resin, a polyurethane resin, etc. Resin, acrylic resin, etc. are used.

  For synthetic resins, antistatic agents, conductive materials, plasticizers, stabilizers, surfactants, lubricants, foaming agents, UV absorbers, light stabilizers, antioxidants, fillers, colorants, etc., as necessary These various additives can be added.

There is no restriction | limiting in particular in the method of using synthetic resin and an ultra-fine long fiber nonwoven fabric to make synthetic leather. For example, synthetic leather can be obtained by a method of extruding and laminating a synthetic resin layer on a long-fiber nonwoven fabric by a known method, a method of laminating and forming by a thermocompression bonding method or paste processing, and the like. Alternatively, a resin is applied on a release paper having a natural leather-like surface texture, and after drying, a two-component polyurethane resin solution adhesive as an adhesive layer is applied on the synthetic resin layer by a known method, A synthetic leather can also be obtained by laminating the ultra-thin fiber non-woven fabric obtained in the present invention thereon and then peeling the release paper. Furthermore, the substrate layer is produced by impregnating the ultra-thin fiber nonwoven fabric of the present invention with a solution or emulsion solution of a polymer elastic resin represented by polyurethane and coagulating the resin by a method such as wet or dry coagulation. A synthetic leather with a silver surface layer is obtained by providing a silver surface layer, and a suede-like or nubuck-like synthetic leather is obtained by buffing the base layer and exposing the ultrafine fibers on the surface. Further, a method of impregnating and coagulating a polymer elastic body in a non-woven fabric before ultrafine treatment may be used.
Synthetic leather obtained in this way has high elongation, so various processed products such as shoe shells, interior material surface materials, camera cases, valuables storage cases and small boxes, etc. Can be processed into deep-drawn molded products.

  Moreover, the high elongation ultrafine fiber nonwoven fabric of this invention can be used suitably also as a surface material of a sound-absorbing material. As an example, an integrated sound-absorbing material can be manufactured by press-heating under the condition that the ultra-thin fiber nonwoven fabric of the present invention is placed on a base material made of glass fiber or felt. At this time, as in the case of the conventional nonwoven fabric, when the molding followability is low, there is a problem that the shape cannot be followed, such as a case where molding is very deep, and the corner portion of the deep drawing is broken. This problem is a phenomenon that needs to be avoided as much as possible, particularly in the case of a sound-absorbing material, because a decrease in thickness leads to a decrease in overall sound-absorbing performance.

  Therefore, by using the ultra-thin fiber nonwoven fabric of the present invention, a sound-absorbing material having excellent molding followability can be obtained at the time of three-dimensional molding, particularly at the time of deep-drawing molding. The sound-absorbing material used exhibits very good sound-absorbing performance compared to the base material used alone. In addition to the improvement in sound absorption performance due to the fact that the fibers used for the surface material are ultrafine fibers, this nonwoven fabric stretches appropriately during molding, ensuring the thickness of the base material, It is estimated that this is because the performance of can be maintained.

  EXAMPLES Next, although an Example demonstrates this invention concretely, this invention is not limited to these Examples. In the examples, each physical property value was measured as follows. In addition, unless otherwise indicated, the part and% in an Example are related with mass.

[Analysis method of PVA]
The analysis method of PVA followed JIS-K6726 unless otherwise specified.
The amount of modification was determined by measurement with a 500 MHz 1H-NMR (JEOL GX-500) apparatus using modified polyvinyl ester or modified PVA.
The content of alkali metal ions was determined by atomic absorption method.

[Method for Analyzing Acid Content in PVA]
Methanol Soxhlet extraction was performed for 3 days using 100 mL of methanol using 20 g of completely dried PVA. A few drops of distilled water (50 mL) and phenolphthalein were added to 50 mL of the extract, and the acid in the extract was neutralized and titrated with an aqueous 1/1000 N sodium hydroxide solution. The content of acid in PVA was converted to acetic acid according to the following formula.
Acetic acid (%) = (0.12 x titer mL x 100) / (1000 x 20)

[Melting point]
The melting point of PVA was increased to 250 ° C. in DS using a DSC (Mettler, TA3000) at a heating rate of 10 ° C./min and then cooled to room temperature, and again up to 250 ° C. at a heating rate of 10 ° C./min. The temperature at the top of the endothermic peak indicating the melting point of PVA when the temperature was raised was examined.

[Spinning state]
The melt spinning state was observed and evaluated according to the following criteria.
◎: Extremely good ○: Good,
Δ: Somewhat difficult ×: Defect

[Nonwoven fabric state]
The obtained nonwoven fabric was visually observed and touched and evaluated according to the following criteria.
◎: Uniform and extremely good ○: Almost homogeneous and good,
Δ: Somewhat difficult ×: Defect

[Nonwoven fabric basis weight, thickness]
It measured according to JIS L1906.

[Average fiber diameter]
Using a scanning electron microscope (SEM), a photograph of the surface of the nonwoven fabric magnified 500 times was taken, two diagonal lines were drawn on this photograph, and the fiber crossing this diagonal line was thickened by the fibers in the vicinity. The value obtained from the further enlarged photograph and converted by magnification was used. And the average value of 100 of these fibers was made into the average fiber diameter, the circle | round | yen which uses this fiber diameter as a diameter was calculated | required, and the fineness of the fiber was computed by making the circle | round | yen into a cross-sectional area.

[Nonwoven fabric strength, elongation at break]
It measured according to JIS L1906.

[Deep-drawing formability of non-woven fabrics]
The obtained ultra-thin long fiber nonwoven fabric was molded into a cup shape having a diameter of 10 cm and a depth of 5 cm using a mold. As a result, the obtained molded product was judged according to the following criteria.
◎: No wrinkles or tears ○: Slight wrinkles occur △: Large wrinkles occur ×: Cracks occur

[Formability of synthetic leather]
The state at the time of the molding test was observed and evaluated according to the following criteria.
◎: Extremely good ○: Good,
Δ: Somewhat difficult ×: Defect

[Appearance after molding test of synthetic leather]
The molded body obtained after the molding test was observed and evaluated according to the following criteria.
◎: Extremely good ○: Good,
Δ: Somewhat difficult ×: Defect

[Sound absorption rate]
The sound absorption coefficient was determined by the normal incidence method according to JISA-1405. Values of 1000 Hz and 2000 Hz were obtained as representative values.

Example 1
[Production of ethylene-modified PVA]
A 100 L pressure reactor equipped with a stirrer, nitrogen inlet, ethylene inlet and initiator addition port was charged with 29.0 kg of vinyl acetate and 31.0 kg of methanol, heated to 60 ° C., and then nitrogen bubbling for 30 minutes. The inside was replaced with nitrogen. Next, ethylene was introduced and charged so that the reactor pressure was 5.9 kg / cm ² (5.8 × 10 ⁵ Pa). Prepare a 2.8 g / L solution of 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile) (AMV) dissolved in methanol as an initiator, and perform nitrogen substitution by bubbling with nitrogen gas. did. After adjusting the temperature inside the polymerization tank to 60 ° C., 170 ml of the initiator solution was injected to start polymerization. During the polymerization, ethylene was introduced to maintain the reactor pressure at 5.9 kg / cm ² (5.8 × 10 ⁵ Pa), the polymerization temperature at 60 ° C., and 610 ml / hr using the above initiator solution. Polymerization was carried out with continuous addition of AMV. After 10 hours, when the polymerization rate reached 70%, the polymerization was stopped by cooling. After the reaction vessel was opened to remove ethylene, nitrogen gas was bubbled to completely remove ethylene. Next, unreacted vinyl acetate monomer was removed under reduced pressure to obtain a methanol solution of polyvinyl acetate.

  46.5 g (in polyvinyl acetate) was added to 200 g of polyvinyl acetate in methanol (100 g of polyvinyl acetate in the solution) adjusted to a concentration of 50% by adding methanol to the obtained polyvinyl acetate solution. Saponification was performed by adding an alkaline solution (NaOH in 10% methanol) having a molar ratio (MR) of 0.10 to the vinyl acetate unit. After about 2 minutes after the addition of alkali, the gelled system was pulverized by a pulverizer, allowed to stand at 60 ° C. for 1 hour to proceed saponification, and then 0.5% acetic acid water / methanol = 20/80. The remaining alkali was neutralized by adding 1000 g of the mixed solution. After confirming the end of neutralization using a phenolphthalein indicator, 2000 g of a mixed solution of water / methanol = 20/80 was added to the white solid PVA obtained by filtration, and the mixture was left to wash at room temperature for 3 hours. After repeating the above washing operation three times, 1000 g of methanol was further added and the mixture was left to wash at room temperature for 3 hours. Then, PVA obtained by centrifugal drainage was left in a dryer at 70 ° C. for 2 days to obtain dry PVA (PVA-1).

  The saponification degree of the obtained ethylene-modified PVA was 98.4 mol%. In addition, after the modified PVA was incinerated, the sodium content measured by an atomic absorption photometer using a material dissolved in an acid was 0.001 part by mass with respect to 100 parts by mass of the modified PVA. Subsequently, 20 g of absolutely dry PVA obtained by vacuum drying the modified PVA obtained above at 50 ° C. for 10 hours was subjected to methanol Soxhlet extraction using 100 mL of methanol for 3 days. The amount of acetic acid measured by neutralizing titration of 50 mL of the extract with 50 mL of distilled water and phenolphthalein and neutralizing the acid in the extract with a 1/1000 N aqueous sodium hydroxide solution is 100 parts by mass of the modified PVA. The value α representing the ratio of acetic acid to sodium ion in PVA was 0.08.

  In addition, after removing the unreacted vinyl acetate monomer after the polymerization, a methanol solution of polyvinyl acetate obtained by precipitation in n-hexane and reprecipitation purification by dissolving with acetone was performed three times, followed by drying at 80 ° C. under reduced pressure for 3 days. To obtain purified polyvinyl acetate. When the polyvinyl acetate was dissolved in DMSO-d6 and measured at 80 ° C. using 500 MHz proton NMR (JEOL GX-500), the ethylene content was 10 mol%. After saponifying the above methanol solution of polyvinyl acetate at an alkali molar ratio of 0.5, the pulverized product was allowed to stand at 60 ° C. for 5 hours to allow saponification to proceed, followed by methanol soxhlet for 3 days, and then at 80 ° C. And purified under reduced pressure for 3 days to obtain purified ethylene-modified PVA. It was 330 when the average degree of polymerization of this PVA was measured according to JIS K6726 of the usual method. Further, a cast film having a thickness of 10 microns was prepared by preparing a 5% aqueous solution of the purified modified PVA. After the film was dried under reduced pressure at 80 ° C. for 1 day, the melting point of PVA was measured by the above-described method using DSC (Mettler, TA3000) and found to be 206 ° C. (Table 1).

  The PVA obtained above was melt-extruded using a Toyo Seiki Co., Ltd. Lab Plast Mill (2-axis, 20 mmφ, L / D = 28) at a set temperature of 220 ° C. and a screw rotation speed of 100 rpm to produce pellets ( Table 1).

The PVA (PVA-1) pellets obtained above and polypropylene (PP) having a melt flow rate (MFR) of 25 g / 10 min and a melting point of 170 ° C. were prepared. Heating up to +/- 1 ° C and melt-kneading, a 16-segment type of 220 ° C so that the mass ratio in the fiber cross section perpendicular to the fiber axis of the composite long fiber constituting the nonwoven fabric is PVA / PP = 30/70 Guided to a composite spinning pack (Fig. 1), discharged from the spinneret under the conditions of nozzle diameter 0.35 mmφ x 1008 holes, discharge rate 625 g / min, shear rate 2500 sec ^-1 , and spinning filament group with cooling air at 20 ° C While cooling, an ejector located 80 cm away from the nozzle was pulled at 1500 m / min with high-speed air and pulled down with a draft 410 to open the fiber. The placement group to form a collecting deposited so long fiber web on the collecting conveyor onto which is rotating endlessly. In the spinning state, no breakage was observed, and the cross-sectional shape was extremely good.

Next, the web was passed between a concavo-convex pattern embossing roll heated to 130 ° C. and a flat roll under a linear pressure of 50 kg / cm, and the embossed part was subjected to thermocompression bonding, whereby a single fiber fineness of 1.85 dtex was obtained. A 16-split composite continuous fiber nonwoven fabric having a basis weight of 88 g / m ² was obtained. The obtained non-woven fabric was homogeneous and very good. The production conditions and production results of the composite long fiber nonwoven fabric are shown in Table 2.

About about 50 m of the obtained composite long fiber nonwoven fabric, splitting and joining treatment of the composite long fiber were performed by a water jet method (water pressure 150 kg / cm ² , nonwoven fabric passage speed 3 m / min). Furthermore, using a circular dyeing machine (water bath 700 L, 90 ° C., nonwoven fabric rotation speed of about 50 m / min), the PVA component in the composite long-fiber nonwoven fabric is completely removed by treatment in hot water for 30 minutes × 2 times. Extracted and removed. Completion of the PVA extraction was confirmed by coloring the nonwoven fabric with an iodine solution. Next, this web was dried for about 1 minute through a hot air dryer at 80 ° C. to obtain a polypropylene extra-fine long fiber nonwoven fabric.
Table 3 shows the results of evaluation of the fineness, basis weight, thickness, physical property values, etc. of the ultra-fine long-fiber nonwoven fabric. The obtained non-woven fabric had good texture, quality and formability and had sufficient elongation.

Example 2
A non-woven fabric made of PVA composite long fibers was obtained under the same conditions as in Example 1 except that the hydroentanglement treatment was not performed. Further, Table 3 shows the results of evaluation of the fineness, basis weight, thickness, physical property value, performance, etc. of the ultra-fine long-fiber nonwoven fabric obtained therefrom. The obtained non-woven fabric had good texture, quality and formability and had sufficient elongation.

Example 3
A nonwoven fabric made of PVA composite long fibers was obtained under the same conditions as in Example 1 except that the MFR values of PP were different. Further, Table 3 shows the results of evaluation of the fineness, basis weight, thickness, physical property value, performance, etc. of the ultra-fine long-fiber nonwoven fabric obtained therefrom. The obtained non-woven fabric had good texture, quality and formability and had sufficient elongation.

Example 4
A PVA system was used under the same conditions as in Example 1, except that the die for composite spinning described in Table 2 was used, the nozzle-ejector distance and the line net speed were adjusted as appropriate, and the hydroentanglement treatment was not performed. A nonwoven fabric composed of composite long fibers was obtained. Further, Table 3 shows the results of evaluation of the fineness, basis weight, thickness, physical property value, performance, etc. of the ultra-fine long-fiber nonwoven fabric obtained therefrom. The obtained non-woven fabric had good texture, quality and formability and had sufficient elongation.

Example 5
A non-woven fabric made of PVA-based composite long fibers was obtained under the same conditions as in Example 1 except that the spinning speed was changed. Further, Table 2 shows the results of evaluating the fineness, basis weight, thickness, physical property value, performance, etc. of the ultra-thin fiber nonwoven fabric obtained therefrom. The obtained non-woven fabric had good texture, quality and formability and had the desired elongation.

Examples 6-12
The PVA described in Table 1 was used instead of the PVA used in Example 1, the thermoplastic polymer described in Table 2 was used, the spinning conditions described in Table 2 were adopted, and the nozzle-ejector distance and line net were appropriately selected. After obtaining the nonwoven fabric which consists of a PVA type | system | group composite long fiber on the same conditions as Example 1 except adjusting speed, it carried out the partial thermocompression bonding at the embossing temperature shown in Table 2, and it was set as the composite long fiber nonwoven fabric. Next, with regard to Example 8, Example 11, and Example 12, water entanglement treatment and PVA extraction treatment were performed under exactly the same conditions as in Example 1. The mass ratio of the composite fiber component was adjusted by changing the amount of polymer introduced into the pack. Table 3 shows the physical property evaluation results, performance, and the like of the obtained ultrafine long fiber nonwoven fabric. The obtained nonwoven fabric had good texture and moldability and had a sufficient elongation.

Comparative Example 1
A nonwoven fabric was obtained under exactly the same conditions as in Example 1 except that the hydroentanglement process and the PVA extraction process were not performed. Tables 2 and 3 show the results of the spinnability and the state of the obtained nonwoven fabric. If the PVA extraction treatment is not carried out, sufficient elongation cannot be imparted to the resulting nonwoven fabric, and ultrafine fibers cannot be obtained.

Comparative Example 2
A PVA system was used under the same conditions as in Example 1, except that the die for composite spinning described in Table 2 was used, the nozzle-ejector distance and the line net speed were adjusted as appropriate, and the hydroentanglement treatment was not performed. A nonwoven fabric composed of composite long fibers was obtained. It shows in Table 3 about the physical-property value, performance, etc. of the obtained ultra-thin long fiber nonwoven fabric. As a result, the nonwoven fabric fineness was as thin as 0.0004 dtex, and the desired elongation was not obtained.

Comparative Example 3
A nonwoven fabric made of PVA composite long fibers was obtained under the same conditions as in Example 1 except that the MFR values of PP were different. Table 3 shows the results of evaluation of the fineness, basis weight, thickness, physical property value, performance, etc. of the ultra-thin fiber nonwoven fabric. A nonwoven fabric having the desired elongation could not be obtained.

Comparative Example 4 and Comparative Example 5
Using the thermoplastic polymer (C) shown in Table 2, using the thermoplastic polymer shown in Table 2, adopting the spinning conditions shown in Table 2, and adjusting the nozzle-ejector distance and the line net speed as appropriate. After obtaining a nonwoven fabric composed of PVA-based composite long fibers under the same conditions as in Example 1, it was partially thermocompression bonded at the embossing temperature shown in Table 2 to obtain a composite long fiber nonwoven fabric. Further, Table 3 shows the results of evaluation of the fineness, basis weight, thickness, physical property value, performance, etc. of the ultra-fine long-fiber nonwoven fabric obtained from this. A nonwoven fabric having the desired elongation could not be obtained.

Comparative Example 6
A nonwoven fabric was produced using only the polypropylene component under the spinning conditions and post-processing conditions shown in Table 2. Tables 2 and 3 show the results of the spinnability and the state of the obtained nonwoven fabric. Sufficient elongation could not be imparted, and since the fineness was high, a nonwoven fabric with a soft and fine texture could not be obtained.

Comparative Example 7
Although the production of the nonwoven fabric was attempted using the PVA shown in Table 1, the yarn was broken frequently due to the generation of gas containing acetic acid and gelation due to the thermal decomposition of PVA, the stable fiber formation could not be performed, and the nonwoven fabric could not be formed. .

Example 13
-Manufacture of synthetic leather, moldability test A sheet made of 0.30 mm vinyl chloride resin was laminated on the ultra-thin fiber nonwoven fabric obtained in Example 1 to prepare a PVC leather. With respect to the moldability of this synthetic leather, a molding process test-1 was carried out using a box mold having a length of 10 cm, a width of 10 cm, and a depth of 5 cm, and the molding state at this time was visually observed. The results are shown in Table 4. Since the nonwoven fabric has high elongation and flexibility, the nonwoven fabric follows the mold, and the skin material does not have wrinkles or cracks and has a high appearance quality.

Example 14
On the ultra-thin fiber nonwoven fabric obtained in Example 1, 0.30 mm olefin resin was subjected to extrusion composite treatment. With respect to the moldability of this synthetic leather, a molding process test 1 was carried out in the same manner as in Example 13, and the molding state at this time was visually observed. The results are shown in Table 4. Since the nonwoven fabric has high elongation and flexibility, the nonwoven fabric follows the mold, and the skin material does not have wrinkles or cracks and has a high appearance quality.

Comparative Example 8, Comparative Example 9 and Reference Example 1
A synthetic leather was obtained in the same manner as in Example 13 except that the base material shown in Table 3 was used, and a molding test 1 was performed. In Comparative Example 8, the nonwoven fabric was not sufficiently stretched, so that tearing occurred after molding. In Comparative Example 9, wrinkles occurred during molding. Moreover, since the fineness was high, the appearance quality and design of the surface of the synthetic leather after processing were lacking. In Reference Example 1, since the melt-blown nonwoven fabric is used as the base material, the fineness is low, but because the nonwoven fabric has insufficient elongation, the moldability is not sufficient and wrinkles are generated. The results are shown in Table 4.

-Sound absorbing material evaluation test Example 15, Comparative Example 10 and Reference Example 2
Felt is prepared as a sound-absorbing material base material, and the nonwoven fabrics obtained in Example 1 and Comparative Example 6 are arranged on the surface, respectively, and a box-shaped mold having a length of 10 cm, a width of 10 cm, and a depth of 10 mm is used. Molded and integrated (molding test 2). The molding state at this time was visually observed. Moreover, the sound absorption rate was measured about the obtained molded object. The results are shown in Table 5.

  From these results, when molding was performed using the nonwoven fabric of Comparative Example 6, the base material was crushed during the molding process, and the thickness after molding was reduced. For this reason, the sound absorption performance has become slightly lower than the mother alone. On the other hand, the sound absorbing material using the nonwoven fabric of Example 1 exhibited an excellent sound absorption rate.

Fiber sectional view showing an example of a composite form of split-type composite long fibers used in the present invention

Explanation of symbols

B: Thermoplastic polymer A: Water-soluble thermoplastic polyvinyl alcohol

Claims (10)

Consists of ultrafine fiber bundles made of thermoplastic polymer, the following requirements (a) and (b)
(A) The single fiber fineness of the ultra-fine long fibers is 0.0005 to 0.5 dtex,
(B) The elongation at break in the length direction of the ultrafine long fiber nonwoven fabric is 100 to 500%,
An ultra-fine long-fiber nonwoven fabric characterized by satisfying both. The ultrathin fiber non-woven fabric according to claim 1, wherein the ultrathin fiber non-woven fabric has a breaking elongation in the width direction of 50 to 500%. The ultrafine long fiber nonwoven fabric according to claim 1, wherein the elongation along the length direction and the width direction of the ultrafine long fiber nonwoven fabric is 100 to 400%. The ultra-fine long-fiber non-woven fabric according to any one of claims 1 to 3, wherein the long-fiber non-woven fabric is bonded using at least one means selected from the group consisting of a heat embossing method, a hydroentanglement method, and a needle punch method. The ultra-thin fiber nonwoven fabric according to any one of claims 1 to 4, wherein the thermoplastic polymer is polypropylene or polyester. Below (A) and (B)
(A) a water-soluble thermoplastic polyvinyl alcohol having a saponification degree of 90 to 99.9 mol%,
(B) Polyethylene terephthalate polyester obtained by copolymerizing polypropylene having an MFR of 30 or less or isophthalic acid having 8 mol% or more,
(A) is dissolved and removed with water from a long-fiber non-woven fabric composed of composite long fibers that can be made into ultra-fine fibers. The method for producing an ultra-thin fiber nonwoven fabric according to claim 6, wherein the thermoplastic polyvinyl alcohol (A) is a modified polyvinyl alcohol containing 0.1 to 15 mol% of an α-olefin unit and / or a vinyl ether unit having 4 or less carbon atoms. . The method for producing an ultra-thin fiber nonwoven fabric according to claim 7, wherein the thermoplastic polyvinyl alcohol (A) is a modified polyvinyl alcohol containing 0.1 to 15 mol% of ethylene units. A synthetic leather in which the ultra-thin fiber nonwoven fabric according to any one of claims 1 to 5 is used as a base fabric. The sound-absorbing material in which the ultra-thin long fiber nonwoven fabric according to any one of claims 1 to 5 is used.

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