JP3032571B2 - Flexible fibrous sheet and multicomponent fiber suitable for its production - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial applications]

The present invention relates to a multicomponent fiber containing polyurethane as a component and suitable as a constituent fiber of a leather-like sheet, and a method for producing a flexible fibrous sheet using the fiber.

[Prior art]

Conventionally, a leather-like sheet made of a microfiber non-woven fabric and an elastomer is highly evaluated as having a texture similar to that of natural leather, such as being more flexible and having a better texture, compared to a non-woven fabric made of a denier fiber. It has been. As a method for producing such a leather-like sheet, a nonwoven fabric of ultrafine fiber-generating fibers is treated with a solvent or the like before or after impregnation with an elastomer to dissolve or decompose and remove one component of the fiber component. A method of forming a fibrous sheet comprising fibers and an elastomer has been widely performed. According to this production method, various textures can be easily produced, but the process for extracting and removing a part of the fiber component becomes complicated and wastes resources. On the other hand, an elastomer is used as one component of the microfine fiber-generating fiber, and the solvent and solution of the elastomer are impregnated to dissolve the elastomer, and then coagulated into a nonwoven fabric without extraction and removal to produce a fibrous sheet. Many have been proposed. For example, with respect to producing a polyurethane-based multicomponent fiber composed of a thermoplastic polyurethane and an inelastic polymer, or a leather-like sheet from the multicomponent fiber, for example, melt-mix spinning of polyamide such as 11-nylon and polyurethane with polyurethane. To make a non-woven fabric from the mixed fiber obtained and process it into a leather-like sheet.
Japanese Patent Publication No. 40-2792 discloses that a mixed sheet of polyurethane and polypropylene is made into a non-woven fabric and processed into a flexible sheet made of ultrafine polypropylene fibers and polyurethane. Alternatively, Japanese Patent Application Laid-Open No. S59-59139 discloses that a mixed fiber is obtained by melt-spinning polystyrene into a mixed fiber, and the mixed fiber and another microfiber-generating fiber are mixed to form a fiber-entangled nonwoven fabric. No. 211664, JP-A-59-211666, JP-A-63-12744, JP-A-2-14056, a polymer having a specific melt flow rate of a thermoplastic polyurethane and a polyolefin or polystyrene-based polymer. combined multicomponent fibers Sho 60-45611, JP-Sho 60-126322 and JP-Sho 64-52820, a terminal amino group concentration of blocked below 3 × 10 ^-5 eq / g Japanese Patent Application Laid-Open No. 60-126359 discloses that a nonwoven fabric of a mixed fiber of polyamide and thermoplastic polyurethane is processed into a fiber sheet, and the core component is polyurethane, the sheath component is an inelastic polymer island phase and a soluble polymer A core-sheath type composite fiber which is a sea-island phase composed of a phase and a fiber in which a large number of inelastic polymer ultrafine fibers are present around polyurethane fine fibers by dissolving and removing a soluble polymer.
No. 47, a polyurethane-based multicomponent fiber using a polyester urethane of a specific component is disclosed in JP-A-62-21820, and a thermoplastic polyurethane is melt-kneaded into polyethylene, polypropylene, etc. and spun to form fibrils. Has been already proposed in Japanese Patent Application Laid-Open No. 48-73514. Further, a split type multi-phase structure fiber in which a polyurethane and an inelastic polymer are joined in multiple phases is disclosed in JP-A-48-28002 and JP-A-52-85575. Japanese Patent Application Laid-Open No. 61-201086 proposes forming a fiber sheet using sea-island type composite fibers that generate polymer ultrafine fibers. Furthermore, it is also known to add an isocyanate composition, polysiloxane, or the like to polyurethane during melt spinning in the production of polyurethane elastic fibers.

[Problems to be solved by the invention]

Using a polyurethane-based multicomponent fiber to produce a fibrous sheet composed of microfibers and porous polyurethane does not include a fiber component extraction / removal step, so the process is simplified and an excellent method without waste of resources. Although many proposals have been made as described above, they have not yet been put to practical use. The biggest reason is that it is difficult to spin such fibers stably for a long time, and even if the fibers can be stably spun, they are processed into a nonwoven fabric, impregnated with a solvent or solution of polyurethane, and coagulated. The reason is that the polyurethane in the multicomponent fiber was not sufficiently porous, and the flexibility of the ultrafine fiber could not be obtained. That is, the conventional method for producing a polyurethane-based multicomponent fiber using polyurethane as one component is a method in which a thermoplastic polyurethane and an inelastic polymer are mixed with a spinning raw material and melt-spinning is performed. A method in which both melts are mixed at the spinning head to form a mixed system using a static mixing method or a dynamic mixing method and then spun, or a thermoplastic polyurethane and an inelastic polymer are mixed in different melt systems. It is performed by a method of melting, regulating both melts with a nozzle, integrating each melt into a multi-core core-sheath type, and performing composite spinning. Of these melt spinning methods, the spinning method of spinning through a melt-mixed yarn stabilizes the fiber phase other than the combination of thermoplastic polyurethane and a specific inelastic polymer, and stably generates little screw and thread breakage. It is difficult to spin continuously for a time. In the spinning method, even if spinning for a short time is stable, if spinning is continued for a long time, deposits are generated around the nozzle of the thermoplastic polyurethane, the fiber phase becomes unstable, and screw generation and thread breakage increase. . Particularly good when the inelastic polymer combined with the polyurethane has an affinity for the polyurethane or a polymer that causes an exchange reaction under spinning conditions, for example, a polymer such as polyamide or polyester, or a water-absorbing / hygroscopic polymer. The spinnability is impaired as well as the formation of a fibrous phase. In particular, when producing a polyurethane-based multi-component fiber in which a non-elastic polymer is a multi-core dispersion component and a fiber phase is formed with polyurethane as a dispersion medium component, the dispersion component of the non-elastic polymer has a relatively uniform circular cross section. It was difficult to spin continuously for a long time. In particular, in the case of a polymer that causes an exchange reaction under the above spinning conditions, separation of the inelastic polymer and the polyurethane by the solvent of the polyurethane is not stable due to the degree of the interfacial reaction. A fiber aggregate is formed using the polyurethane-based multicomponent fiber obtained in this manner, and then impregnated with a polyurethane solvent to dissolve the polyurethane in the mixed spun fiber. The separation was insufficient and uneven, and it was difficult to stably produce a high-strength flexible fibrous sheet even if the substrate was introduced into a coagulation bath, then washed with water and dried. SUMMARY OF THE INVENTION An object of the present invention is to provide a polyurethane-based multicomponent fiber in which polyurethane is used as a dispersion medium component and an inelastic polymer is used as a dispersion component. . Second, even when polyester or polyamide, which could not be stably spun in the past, is used as one component, the phase of each component is stable, and the separability between the inelastic polymer and the polyurethane by the solvent of the polyurethane is low. The purpose is to provide good multicomponent fibers.
Another object is to stably produce a high-strength flexible fibrous sheet using the fibers.

[Means for Solving the Problems]

The present invention is a fibrous sheet in which polyurethane is contained in a porous form in a nonwoven fabric made of bundle fibers of ultrafine fibers, and at least the porous polyurethane contained inside the ultrafine fiber bundle has a saturated hydrocarbon skeleton. A flexible fibrous sheet comprising a thermoplastic polyurethane having a polyolefin segment comprising a polyolefin segment comprising a polyolefin segment comprising a saturated hydrocarbon skeleton. Is made of a polyurethane-based multicomponent fiber having an incompatible thermoplastic polymer as a dispersing component or a fiber assembly mainly comprising the same, and then a solvent of the polyurethane component and a non-solvent of another component or Impregnated with a solution of the same or a different polyurethane as the polyurethane, A method for producing a flexible fibrous sheet, comprising dissolving urethane, guiding the substrate into a coagulation bath, then washing with water, and drying. The present invention also relates to a polyolefin comprising a saturated hydrocarbon skeleton. A thermoplastic polyurethane having a segment as a dispersion medium component,
The polyurethane is a polyurethane-based multicomponent fiber characterized by using an incompatible thermoplastic polymer as a dispersing component. The thermoplastic polyurethane constituting the multicomponent fiber of the present invention is a low-molecular-weight polyolefin having a reactive organic functional group with an average molecular weight of less than 500 to 5,000 having a saturated hydrocarbon skeleton in the main chain and / or side chain, preferably in the main chain. It is a thermoplastic polyurethane obtained by reacting a compound or an intermediate containing a polyolefin compound, other polymer diol, organic diisocyanate, and a raw material mainly composed of four components of a low molecular compound having two active hydrogen atoms. A preferred polyurethane that forms a dispersion medium phase in the fiber is a polyurethane having an intrinsic viscosity [η] in the range of 0.7 to 1.8 dissolved in an N, N-dimethylformamide solvent, and the amount of the hard segment occupied in the polyurethane. However, when a diol compound or a hydroxyamine compound is used as a chain extender, 30 to 60% by weight, more preferably 35 to 50%
20% by weight when the amine compound is used as a chain extender.
It is in the range of 40% by weight. If the thermoplastic polyurethane is out of these ranges, the melt viscosity does not form the desired fiber phase, but the fiber phase is inverted or unclear, or the spinnability is impaired. The polyolefin compound characterizing the present invention is a low-molecular-weight polyolefin compound having a reactive organic functional group at a terminal having an average molecular weight of 500 to 5,000 having a saturated hydrocarbon skeleton having no double bond in a main chain and / or a side chain. Polytail series (Mitsubishi Kasei Kogyo Co., Ltd.) as a commercial product
There are polyolefin polyols having a primary hydroxyl group at the terminal, such as the following compounds. In addition, any low-molecular-weight polyolefin compound having a reactive organic functional group such as an amino group, a carboxyl group, or an epoxy group at a molecular terminal can be used in the present invention. Furthermore, in the case of a low-molecular-weight polyolefin having a reactive organic functional group such as a hydroxyl group, an amino group, a carboxyl group, or an epoxy group at a molecular terminal, the polyolefin is reacted with a polymer diol, a chain extender, or a polycarboxylic acid or an amine described below. Polyester polyols, polyamide polyamines, polyether polyols and the like obtained by the above method can be used in the same manner. Although any polyurethane-based resin containing a polyolefin compound obtained from the above-mentioned materials can be used in the present invention, preferred is a resin in which the amount of the polyolefin segment accounts for 5 to 30% by weight of the total amount of the polyurethane resin. 5 polyolefin segments
If the amount is less than 30% by weight, the intended purpose of the present invention will be insufficiently achieved. Representative polymer diols used in combination with the polyolefin compound include, for example, polyethylene adipate, polyethylene propylene adipate, polybutylene adipate, polyhexamethylene adipate, poly-3
Polymethyl diols such as -methyl-1,5-pentane adipate, polyoctane adipate, polynonane adipate, etc. Polycarbonate diols such as carbonate diol, polyethylene ether glycol, polypropylene ether glycol,
At least one kind of polymer diol selected from polyether glycols such as polyether glycols such as polytetramethylene ether glycol and polyhexamethylene ether glycol, and polyether polyester block copolymer glycols. Organic diisocyanates constituting the hard segment include aromatic diisocyanates such as tolylene diisocyanate, xylylene diisocyanate, 4,4'-diphenylmethane diisocyanate, aliphatic diisocyanates such as 4,4'-dicyclohexyl methane diisocyanate, and isophorone diisocyanate, and naphthalene. At least one organic diisocyanate selected from diisocyanates and the like. And as a chain extender,
Diethylene such as ethylene glycol, butylene glycol, hexamethylene glycol, 3-methyl-1,5-pentanediol, ethylenediamine, hexamethylenediamine, 4,4'-dicyclohexylmethanediamine, at least selected from diamines such as isophoronediamine One type of compound. On the other hand, the inelastic polymer has a melting temperature selected from, for example, polyamide, polyester, polyesteramide, and the like.
It is a thermoplastic polymer having a melt flow rate (hereinafter referred to as MFR) value of a polymer measured at 160 to 250 ° C and a spinning temperature smaller than the MFR value of the thermoplastic polyurethane. As this polyamide, for example, 6-nylon, 6 / 10-
Nylon, a polyamide selected from 10 / 9-nylon, 10 / 10-nylon, 11 nylon, 12 nylon, 6,6 / 6-nylon, 6,12-nylon, etc., preferably having a terminal amino group concentration of 3 × 10 ⁻⁵ eq / g or less, more preferably 1.5
Stable spinning can be performed by using a polyamide of × 10 ⁻⁵ eq / g or less. Also, as polyester,
For example, it is a polyester selected from polybutylene terephthalate, polyhexamethylene terephthalate, polyethylene terephthalate copolymer, polyester / polyamide block copolymer, and the like. Next, the polyurethane multicomponent fiber can be spun according to a conventionally known melt spinning method.
That is, thermoplastic polyurethane having a polyolefin segment in the main chain and / or side chain is melted in one melt system, and the inelastic polymer is melted in the other melt system. A method of forming a mixed system and spinning, or melting a thermoplastic polyurethane having a polyolefin segment in a main chain and / or a side chain in one melt system and melting an inelastic polymer in the other melt system, respectively. The polyurethane melt is converted into a sheath component (or sea component) with a nozzle using a nozzle, and the inelastic polymer melt is regulated into a multi-core core component (or island component) and integrated into a multi-core core-sheath type. It is carried out by a method of composite spinning. In particular, a high effect is exhibited in the spinning method of the present invention. The spinning temperature varies depending on the melt flow temperature of the thermoplastic polyurethane used, the thermal behavior such as thermal dissociation temperature, and the melt flow temperature of the inelastic polymer, but is preferably 220 to 260 ° C.
Range. If the spinning temperature is out of this range, an unfavorable state occurs in the polyurethane, and stable spinning cannot be performed because a stable fiber phase cannot be formed. The composition ratio between the polyurethane dispersion medium component and the inelastic polymer dispersion component is as follows:
The content of the polyurethane dispersant is in the range of 10 to 60% by weight from the viewpoint of the stability of the fiber phase. The fiber cross-sectional shape of the polyurethane-based multicomponent fiber obtained by the spinning of the present invention is such that the inelastic polymer has a large number of dispersion components (core components) having a substantially circular or elliptical shape (including a rounded rectangle), and polyurethane has a dispersion medium component. It is a multi-core sheath-type composite fiber (or sea-island type fiber) that has become (sheath component). This multi-component fiber is 1.5 to 10 by wet heat drawing or dry heat drawing.
It is drawn twice, and if necessary, heat-set and mechanically crimped to obtain a fiber to be used. The multicomponent fiber is a cross-wrap web or a random web, and the weight is required depending on the intended product orientation, but is usually 100 to 2000 g / m ² . Next, a fiber entangled nonwoven fabric is formed by needle punching or high-speed fluid flow treatment. Further, it may be a woven or knitted fabric or a raised fabric of those fabrics. After making these fiber aggregates,
Solvents for the polyurethanes making up the fibers, e.g. N, N
-A colorant, activator, if necessary, by treating with a commonly used solvent such as dimethylformamide, dimethylsulfoxide, tetrahydrofuran, or on the same or different polyurethane as the polyurethane constituting the fiber;
Treat with a solution to which fillers and other additives have been added,
A part or all of the polyurethane constituting the fibers is dissolved, and the dissolved material is retained in the fiber aggregate and wet-coagulated to obtain a fibrous sheet. The obtained fibrous sheet may be sueded artificial leather by finishing its surface into fibrous naps, or may be coated with a coating layer on the surface or simply smoothed and then applied with a colored finishing layer to finish the silver sheet. Artificial leather may be used. The fibrous sheet obtained by the method of the present invention has better separability between the inelastic polymer fiber and the polyurethane sponge than the fibrous sheet obtained by the same conventional method.
It has a texture similar to that of natural leather, and is a fibrous sheet having remarkably improved properties such as tensile breaking strength, tear strength, creep, and elastic recovery.

【Example】

Next, embodiments of the present invention will be described with reference to specific examples. The parts and percentages in the examples relate to weight unless otherwise specified. Examples 1, 2, Comparative Example 1, 23 Polyester diol having an average molecular weight of 1500 composed of 3-methyl-1,5-pentanediol and adipic acid,
A polyolefin polyol having an average molecular weight of 1500 represented by the following formula [1], (A), a polymer diol mixed so that the polyolefin polyol ratio in the total amount of the polyurethane resin is 10% (B), 25% (C) or 40% (D), 4,4'-diphenylmethane diisocyanate (Hereinafter M
DI) and 1,4 butanediol (BD)
Was melt-polymerized to obtain four types of thermoplastic polyurethane pellets in which the nitrogen weight percentage attributed to MDI was 4.0%. The pellets of the four types of thermoplastic polyurethanes (A, B, C, and D) obtained in this manner are used as spinning raw materials, and polymer streams melted by two extruder melting systems are joined at the spinning head and divided. -Using a multi-component fiber production device that forms a mixed stream by melt-spinning using a static mixing method that repeats integration, charges the polyurethane into one of the melting systems in a dry nitrogen gas atmosphere and melts at a melting zone temperature of 250 ° C. Then, 6-nylon having a terminal amino group concentration of 1.5 × 10 ⁻⁵ eq / g was melted in the other molten system, melted at a melting zone temperature of 250 ° C., and each melt stream was measured with a metering pump, and the polyurethane stream was measured. 20, 6-
The nylon stream is joined at the spinning head at a rate of 80, and the spinning temperature is 25.
The fiber was spun at 0 ° C. and a winding speed of 700 m / min to produce a 10-denier composite fiber. Each spinning stability, state of fiber phase,
Table 1 shows the thread properties and solubility in N, N-dimethylformamide (DMF). That is, in Examples 1 and 2 using thermoplastic polyurethane B or C, almost stable spinning could be performed, yarn physical properties were high, fiber dispersed phase was good, and fine fibers when treated with DMF were used. Thus, a fiber having good separability was obtained. On the other hand, in Comparative Example-1 in which the thermoplastic polyurethane A containing no polyolefin polyol component was used, generation of screws and breakage were large, the fiber shape was uneven, and stable spinning could not be performed. Furthermore,
When the spin pack was disassembled, many brownish scales were generated in the spin pack. In addition, the separation of fine fibers when treated with DMF was poor. On the other hand, in the case of Comparative Example-2 in which the polyolefin polyol component was contained in the polyurethane resin at 40%, generation of screws and breakage increased, and the fiber shape became irregular. The obtained multicomponent fiber is stretched three times in hot water at 80 ° C,
Heat setting was performed to obtain fibers having a fineness of 3.5dr. After applying the oil agent, the fibers were mechanically crimped and cut to a fiber length of 51 mm to obtain staple fibers. Next, each staple fiber passes through a card and a random webber, respectively, and is laminated by a cross wrap method to obtain an average weight.
After making a fiber web of 450 g / m ² , needle punching is performed from both sides of the fiber web at a total punch density of 980 punch / cm ² to obtain a fiber entangled nonwoven fabric, impregnated with a 5% aqueous solution of polyvinyl alcohol, and a target drawing rate of 150%. After squeezing and drying to form a nonwoven fabric having a stable form, a mixture of 2-methyl-1,8-octanediol and 1.9-nonanediol (molar ratio 50/50)
Polyester diol having an average molecular weight of 2,000 obtained by condensation of adipic acid and adipic acid and a mixed diol of polyethylene glycol having an average molecular weight of 2,000 (mixing ratio: 85:15) / MDI / ethylene glycol Impregnate with a 10% DMF solution at an impregnation rate of 200%,
The polyurethane in the fiber was dissolved in an atmosphere at 45 ° C. Next, the polyurethane was coagulated by immersion in a 30% aqueous solution of DMF and treated in hot water at 95 ° C. to remove the solvent and polyvinyl alcohol. One surface side of the obtained fibrous sheet was sliced to a thickness of 1.0 mm, the surface side at the time of solidification was raised to a suede-like sheet, dyed and kneaded to obtain a product. The performance is shown in Table 2. The products of Examples had good heat fixability by ironing, and were excellent as a suede-like sheet with a stiff and soft texture with less fluff falling off. When the fibrous sheet was observed with a scanning electron microscope photograph, the fibrous sheets of Examples 1 and 2 showed that the ultrafine fiber bundle fiber of nylon and the sponge of polyurethane were well separated, and the fiber of Comparative Example-1. The quality sheet was poorly separated with a polyurethane sponge wrapped around the nylon. Examples-3,4, Comparative Examples-3,4 Polytetramethylene glycol having an average molecular weight of 1,000 containing no polyolefin polyol [1] (E), and a polyolefin polyol ratio in the total amount of polyurethane resin of 10% (F) , 25% (G) or 40% (H)
Polymer diol, MDI and BD
To obtain four types of thermoplastic polyurethane pellets in which the nitrogen weight percentage attributed to MDI is 4.0%. The thermoplastic polyurethane pellets (E, F, G, and H) obtained in this manner were used as spinning raw materials, and a polybutylene terephthalate in which a terminal hydroxyl group was blocked with succinic anhydride as an inelastic polymer was used as in Example 1. Similarly, 50 parts of a polyurethane stream and 50 parts of a polybutylene terephthalate stream were combined at the spinning head, and the spinning temperature was 250 ° C. and the winding speed was 700.
The fiber was spun at m / min to produce a 12 denier composite fiber. Table 3 shows the results. From Table-3, in the case of Example-3 and Example-4 spun using the polyurethane (F) or (G) of the present invention, the yarn physical properties are high, the fiber dispersed phase is good, and the fiber is treated with DMF. It can be seen that the fibers having good separability of the fine fibers can be stably obtained. On the other hand, in Comparative Example-3 using the ordinary polyether-based diol (E), the thermal stability of the polyurethane was poor, the generation of screws and thread breakage were large, the fiber shape was uneven, and the spinning was stable. could not.
When the spin pack was disassembled, many brownish scales were generated in the spin pack. Furthermore, because of the good affinity with the polybutylene terephthalate of the dispersed phase, DM
The separation property of the fine fibers when treated with F was poor.
On the other hand, Comparative Example using polyurethane (H) containing 40% of polyolefin polyol component in polyurethane resin-
Also in the case of No. 4, screw generation and thread breakage increased, and the fiber shape became irregular. The obtained multicomponent fiber was treated in the same manner as in Example 1,
Staple fiber with a fineness of 4dr and a fiber length of 51mm by mechanical crimping, and a fiber web through a card and random webber, after laminating by a cross lap method, performing a needle punching process from both sides, and then water pressure 70kg / was treated by applying a high pressure columnar water streams in cm ^2, and dried to average weight 720 g / m ²
Was obtained. This nonwoven fabric is impregnated with DMF containing water-soluble silicon at a target liquid content of 200%, and treated on a polyethylene belt at 55 ° C for about 2 minutes.
The leached polyurethane was coagulated in the nonwoven fabric by immersion in an F aqueous solution. The surface of the obtained fibrous sheet that has been subjected to water flow treatment
After pressing against a smooth metal belt surface heated to 135 ° C, the surface is smoothed, and then a polyurethane colored layer and a resin layer mainly composed of polycarbonate-based polyurethane are applied to the surface. It was patterned with a roll to obtain a leather-like sheet. Table 4 shows the physical properties of the obtained sheet. In other words, the product of the example is a strong, leather-like, waist-like and flexible material, which stretches 10% in both the vertical and horizontal directions, and is attached to a wooden tub-shaped wooden surface, and the surface can be seen by the gloss change occurring on the surface. The unevenness (also called fishing or orange peel) was excellent in the second grade of judgment. However, the products of Comparative Examples 3 and 4 have irregularities in the texture, and when bent, have a streak-like fold and are not good in appearance. Further, in the evaluation of fishing haul, large irregularities were conspicuously judged at class 4.5, and the evaluation as a product was poor.

【The invention's effect】

The present invention relates to the production of a polyurethane multicomponent fiber,
By using a thermoplastic polyurethane having a polyolefin segment consisting of a saturated hydrocarbon skeleton as a dispersion medium component, polyester having affinity for polyurethane, even in the case of a polyurethane-based multicomponent fiber having a polymer such as polyamide as a dispersion component, Low thread breakage due to less screw generation and die stain, and stable fiber phase, continuous spinning can be performed stably for a long time, and the obtained multi-component fiber has less sticking and crimp stability. Good fiber.
In addition, this multicomponent fiber has good separability in a solvent of polyurethane such as N, N-dimethylformamide, and a fiber aggregate is formed using the polyurethane multicomponent fiber, and a solution containing the polyurethane solvent or the polyurethane is used. By impregnating and dissolving the polyurethane in the multicomponent fiber and then wet coagulating, a flexible fibrous sheet can be obtained. Furthermore, the polyurethane is eluted from the multicomponent fiber with a solvent,
Since the eluted polyurethane can be re-coagulated and used, the production of the fibrous sheet can be streamlined and resources can be saved.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ identification code FI D06M 15/564 (58) Investigated field (Int.Cl. ⁷ , DB name) D06N 3/14 D06M 13/402 D06M 15/564 D01F 8/16

Claims (3)

(57) [Claims] 1. A fibrous sheet in which polyurethane is contained in a porous form in a nonwoven fabric comprising bundles of ultrafine fibers, wherein the porous polyurethane contained in at least the inside of the ultrafine fiber bundle has a saturated hydrocarbon skeleton. A flexible fibrous sheet comprising a thermoplastic polyurethane having a polyolefin segment comprising: 2. Polyurethane-based multicomponent fibers comprising a thermoplastic polyurethane having a polyolefin segment having a saturated hydrocarbon skeleton as a dispersion medium component and a thermoplastic polymer incompatible with the polyurethane as a dispersion component, or a polyurethane multicomponent fiber as a main component. A fiber assembly is made from the fibers obtained, and then impregnated with a solvent that is the solvent of the polyurethane component and a non-solvent of the other component or a solution of the same or different polyurethane as the polyurethane, and dissolves the polyurethane in the multi-component fiber. A method for producing a flexible fibrous sheet, comprising introducing a substrate into a coagulation bath, followed by washing with water and drying. 3. A polyurethane multicomponent fiber comprising a thermoplastic polyurethane having a polyolefin segment having a saturated hydrocarbon skeleton as a dispersion medium component and a thermoplastic polymer incompatible with the polyurethane as a dispersion component. .