JP2011074541A - Napped artificial leather having excellent pilling resistance - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a napped artificial leather having both favorable napped feeling and high pilling resistance and a method for manufacturing such napped artificial leather. <P>SOLUTION: A napped artificial leather comprises a nonwoven fabric structure formed of fiber bundles of ultrafine filaments and a polymeric elastic body arbitrarily contained inside the nonwoven fabric structure, and has ultrafine filaments at least on one surface. The fiber bundles of ultrafine filaments are formed by removing water-soluble resin from conjugate filaments containing the water-soluble resin. The napped artificial leather contains a polymeric elastic body obtained from water dispersion of the polymeric elastic body at a root of a nap and in proximity thereto. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a napped artificial leather (suede-like artificial leather) comprising a nonwoven fabric structure comprising ultrafine fiber bundles optionally containing a polymer elastic body, and having napped fibers comprising the ultrafine fibers on at least one surface of the nonwoven fabric structure. Leather and nubuck-like artificial leather) and a method for producing the same. Since the polymer elastic body obtained from the aqueous emulsion exists in the vicinity of the root of the napped fiber, the napped artificial leather has a good nap appearance and texture and is excellent in pilling resistance.

  Conventionally, napped artificial leather such as suede artificial leather and nubuck artificial leather in which napped fibers are formed on the surface of a base material (nonwoven fabric structure) for artificial leather consisting of a fiber bundle and a polymer elastic body is known. It is. Napped-toned artificial leather has not only a demand in terms of sensibility such as appearance (surface feeling closer to that of natural leather) and texture (combination of soft touch, moderate swelling and fullness), but also pilling resistance and wear resistance. There is a demand for satisfying all the demands on physical properties such as properties at a high level, and various proposals have been made to solve this.

  In order to satisfy the requirements in appearance and texture, for example, a method of making the fibers constituting the artificial leather into ultrafine fibers is generally used. One method of manufacturing artificial leather made of ultrafine fibers is to split composite long fibers such as sea-island fibers or multi-layer bonded fibers, or transform them into ultrafine fiber bundles by decomposing or extracting one component. Widely adopted. Napped-toned artificial leather using a base material for artificial leather in which a non-woven fabric composed of ultrafine fiber bundles is incorporated with a polymer elastic body as necessary has been highly evaluated in terms of appearance and texture. However, when the fineness of the napped fibers is reduced, the napped fibers are easily entangled and pilling is likely to occur.

  In order to improve the pilling resistance of the raised surface, for example, the degree of entanglement of the non-woven fabric structure is increased, or a large amount of a polymer elastic body is contained in order to bond the fibers together or to strongly restrain the fibers. The method is generally adopted. However, when the degree of entanglement is increased or the content of the polymer elastic body is increased, the texture of the artificial leather is remarkably deteriorated, and the surface properties such as appearance, texture and pilling resistance can be satisfied at the same time. It was difficult.

  Patent Document 1 proposes to improve the pilling resistance of napped artificial leather by including coarse particles inert to fibers having a diameter larger than one-fourth of the fiber diameter in ultrafine fibers. is doing. It is described that the coarse particles become weak points, and the nappings are cut at the weak points before the nappings are entangled to form pilling, thereby obtaining a pilling resistance effect. However, in the method described in Patent Document 1, since the sea component of the sea-island fiber is extracted and removed, the polyurethane is impregnated and solidified with a dimethylformamide (DMF) solution of polyurethane. Curing is inevitable. In addition, since coarse particles are added to the napped fibers, a soft texture and feel cannot be obtained.

  Patent Document 2 discloses that a part of a polymer elastic body existing at the root of a napped fiber is dissolved with a solvent such as DMF, and the piling resistance of the napped artificial leather is improved by fixing the root of the napped fiber. is suggesting. However, in the manufacturing method described in Patent Document 2, it is inevitable that the texture becomes hard because the polymer elastic body exists inside the ultrafine fiber bundle. In addition, the effect of fixing the fibers inside the base material for artificial leather is poor, and because the holding ability of the polymer elastic body to the fibers is low, the effect of improving the good pilling resistance for fibers of 0.01 dtex or more Cannot be obtained.

  In Patent Document 3, a fiber bundle composed of fine fibers (A) having a large fineness and ultrafine fibers (B) having a small fineness is raised by buffing or the like, and the number ratio A / B of the fine fibers (A) and the ultrafine fibers (B) is obtained. It is proposed to form napped hairs that are 3/1 or more. Thus, it is described that the ultrafine fiber (B) can be entangled with the fine fiber (A) and prevent pilling. Before the sea-island fiber is made ultrafine, it is impregnated and solidified with a DMF solution of the polymer elastic body, so there is virtually no polymer elastic body on the outer periphery and inside of the ultrafine fiber bundle, giving it a soft texture and feel. It is possible to obtain. However, since the ultrafine fiber bundle is not fixed by the polymer elastic body, the pilling resistance is insufficient.

  Patent Document 4 discloses a surface of voids in an elastic body, an ultrafine fiber bundle obtained by forming napped on a substrate surface containing a polymer elastic body, then applying a fine particle dispersion and impregnating the inside of the substrate. Disclosed is a suede-like sheet with fine particles adhering to the inner or outer surface. However, the technique described in Patent Document 4 is intended to improve the mechanical strength of the polymer elastic body and the ultrafine fiber bundle by adhering fine particles, and any improvement in the pilling resistance of napped fibers has been studied. Not.

  Patent Document 5 proposes raising polyester ultrafine fibers containing silica having a particle size of 100 nm or less to make napped fibers. By containing silica, the breaking strength of the polyester ultrafine fiber is reduced, that is, the strength of the napped fiber is lowered so that the napped fiber is cut before pilling occurs to prevent pilling. However, although the occurrence of pilling is reduced, the wear loss is large and there is a problem in practical use.

  Patent Document 6 proposes in Example 1 that a dimethylformamide solution containing 5% of a solid content of polyurethane resin is applied to a raised surface of a substrate containing a polymer elastic body by a gravure coater. However, in the manufacturing method described in Patent Document 6, since the polymer elastic body exists inside the ultrafine fiber bundle, it is inevitable that the texture becomes hard. In addition, the feeling of nap on the surface is taken away, and a soft texture and touch cannot be obtained.

JP 53-034903 A JP-A-57-154468 JP-A-7-173778 Japanese Patent Laid-Open No. 9-250063 JP 2004-339617 A JP 2007-262616 A

  As mentioned above, it is difficult to satisfy the surface properties such as the appearance and texture of the napped at the same time, and the pilling resistance, and the napped tone with sufficiently improved pilling resistance without impairing the feeling of napping (appearance and texture). Artificial leather was not offered. It is an object of the present invention to provide a napped artificial leather having both a good nap feeling and high pilling resistance and a method for producing such a napped artificial leather.

  As a result of intensive studies to achieve the above object, the inventors of the present invention have provided a polymer elastic body on the raised surface obtained by raising an ultrafine fiber bundle obtained by ultrafinening a composite long fiber containing a water-soluble resin. When an aqueous dispersion is applied and dried, the polymer elastic body does not cover the upper part of the napped fiber and is present at the base of the napped fiber and in the vicinity thereof, and the napped-toned artificial leather has a good nap feeling and high surface properties. The present invention has been completed by finding out that it has (wear resistance, pilling resistance, etc.).

  That is, the present invention comprises a nonwoven fabric structure composed of a bundle of ultrafine fibers, and a polymer elastic body arbitrarily contained in the nonwoven fabric structure, and the raised fibers of the ultrafine fibers are provided on at least one surface. A napped-toned artificial leather having a fiber bundle of ultrafine fibers formed by removing the water-soluble resin from a composite long fiber containing a water-soluble resin. The present invention relates to a napped artificial leather having a polymer elastic body obtained from an aqueous dispersion of the body.

Furthermore, the present invention provides the following steps (a) to (e):
(A) a step of making a composite long fiber containing a water-soluble resin into a long fiber web;
(B) entanglement treatment of the long fiber web to obtain an entangled nonwoven fabric structure;
(C) a step of extracting and removing a water-soluble resin from the composite long fibers constituting the entangled nonwoven fabric structure with water or an aqueous solution, and transforming the composite long fibers into a fiber bundle of ultrafine fibers to obtain an ultrafine nonwoven fabric structure ,
(D) a step of raising at least one surface of the ultrathinned nonwoven structure to form napped to obtain a napped nonwoven structure; and (e) applying an aqueous dispersion of a polymer elastic body to the napped surface. Then, a process of solidifying the polymer elastic body to obtain a napped artificial leather,
The present invention relates to a method for producing napped-tone artificial leather.

  In the napped artificial leather of the present invention, there is a polymer elastic body obtained from an aqueous dispersion of the polymer elastic body at and near the root of the napped without covering the surface of the napped consisting of ultrafine fibers. Since it has such a raised surface, the surface properties such as abrasion resistance and pilling resistance are improved without impairing the raised feeling (appearance and texture) in the raised artificial leather of the present invention.

It is an electron micrograph (50 times) which shows the surface of the napping nonwoven fabric structure of Example 1 (before application | coating of the water-system emulsion of a polymeric elastic body). It is an electron micrograph (100 times) which shows the cross section of the napping nonwoven fabric structure of Example 1 (before application | coating of the water-system emulsion of a polymeric elastic body). It is an electron micrograph (50 times) which shows the surface after apply | coating the water-based emulsion of a polymeric elastic body to the napped nonwoven fabric structure surface of Example 1, and drying. It is an electron micrograph (100 times) which shows the cross section after apply | coating the water-based emulsion of a polymeric elastic body to the napped nonwoven fabric structure surface of Example 1, and drying. It is an electron micrograph (50 times) which shows the surface of the napping nonwoven fabric structure of the comparative example 1 (before water-system emulsion application | coating of a polymeric elastic body). It is an electron micrograph (100 times) which shows the cross section of the napping nonwoven fabric structure of Comparative Example 1 (before applying a water-based emulsion of a polymer elastic body). It is an electron micrograph (50 times) which shows the surface after apply | coating the water-based emulsion of a polymeric elastic body on the surface of the napped nonwoven fabric structure of the comparative example 1, and drying. It is an electron micrograph (100 times) which shows the cross section after apply | coating the water-based emulsion of a polymeric elastic body on the surface of the napped nonwoven fabric structure of the comparative example 1, and drying.

  The napped-tone artificial leather of the present invention is composed of a nonwoven fabric structure comprising ultrafine fiber bundles, and a polymer elastic body optionally contained in the nonwoven fabric structure, and raising the ultrafine fiber bundles on at least one surface. For example, it can be obtained by sequentially carrying out the following steps (a) to (e).

Step (a)
A composite long fiber composed of a fiber-forming water-insoluble resin and a water-soluble resin is melt-spun, and the obtained composite long fiber is accumulated in a collection surface such as a net in a random orientation state without cutting, and is obtained as desired. A long fiber web having a basis weight, preferably 10 to 1000 g / m ² , is produced. The single fiber fineness of the composite long fiber is preferably 0.9 to 4.9 dtex, more preferably 1.9 to 3.9 dtex.

Step (b)
A plurality of layers of the long fiber web are laminated in the thickness direction using a cross wrapper or the like, if necessary, and at least 6 barbs are used, and one or more barbs penetrate at the same time or from both sides. By alternately needle punching, fibers are three-dimensionally entangled to obtain an entangled nonwoven fabric structure. For long fiber webs, an oil agent that has an antistatic effect at any stage after its manufacture and until the entanglement treatment, an oil agent for controlling the friction resistance with the needle, an oil agent for controlling the friction resistance between fibers, etc. May be added alone or in combination.

Step (c)
A water-soluble resin is extracted and removed from the composite long fibers constituting the entangled nonwoven structure with water or an aqueous solution, and the composite long fibers are transformed into fiber bundles of ultra-fine fibers to obtain an ultra-fine nonwoven structure (simply referred to as a non-woven structure and Sometimes called).

Step (d)
At least one surface of the ultrafine nonwoven fabric structure is subjected to raising treatment such as buffing to raise an ultrafine fiber bundle in the vicinity of the surface to obtain a napped nonwoven fabric structure.

  Before making the entangled nonwoven fabric structure obtained in step (b) ultrafine or before raising the ultrafine nonwoven fabric structure, the nonwoven fabric structure is impregnated with an aqueous dispersion of a polymer elastic body, The polymer elastic body may be solidified to form a polymer elastic body-containing nonwoven fabric structure.

Step (e)
An aqueous dispersion of a polymer elastic body is applied to at least one surface of the napped nonwoven fabric structure, and then the polymer elastic body is solidified to obtain the napped-tone artificial leather of the present invention.

Hereinafter, the present invention will be described in more detail.
The composite long fiber used in the present invention is a multicomponent fiber composed of at least two kinds of resins including a water-soluble resin, and is converted into a fiber bundle of ultra-fine long fibers by extracting and removing the water-soluble resin with water or an aqueous solution. It is a long fiber (ultrafine fiber generation type long fiber) that can be made. The composite long fiber is selected from a sea-island fiber, a multilayer laminated fiber, a split fiber and the like obtained by a mixed spinning method, a composite spinning method, or the like.

  Examples of fiber-forming (melt-spinnable) water-insoluble resins that become ultrafine fibers after ultrafine treatment include, for example, polyethylene terephthalate (PET), polytrimethylene terephthalate (PTT), polybutylene terephthalate (PBT), polyester elastomer, etc. Polyester resins or modified products thereof, polyamide resins or modified products thereof, polyolefin resins or modified products thereof, and the like. When a structure in which ultrafine fiber bundles are densely assembled is desired, polyester resins such as PET, PTT, PBT, or modified products thereof, heat-shrinkable polyamide resins or modified products thereof, heat-shrinkable polyolefin resins or A heat-shrinkable resin such as a modified product is preferred. Using heat-shrinkable resin makes it possible to produce artificial leather with good physical characteristics such as fine surface feeling, solid texture and other features such as wear resistance, light resistance, and form stability. can get. In particular, when a fiber made of the above-mentioned polyester resin or polyolefin resin, which is a so-called hydrophobic resin having water repellency in the resin, is applied to the present invention, a remarkable effect is recognized. Details of this effect are unknown, but a small amount of water-soluble resin adheres to the surface of the polyester resin to suppress the water repellent effect of the polyester resin, and the aqueous dispersion of the polymer elastic body is made of napped fibers. Not only the outermost surface of the artificial leather, but also penetrates and diffuses to the roots of the naps made of ultrafine fibers and the vicinity thereof to fix the ultrafine fibers. On the other hand, the ultrafine fibers converge from the naps root to the inside of the nonwoven structure. Thus, a state in which the polymer elastic body hardly penetrates into the inside of the ultrafine fiber bundle can be obtained in the original ultrafine fiber bundle. Accordingly, it is considered that the effect of suppressing pilling is realized by stopping the root of the napped without significantly impairing the texture even though the polymer elastic body is present on the surface layer.

  The melting point (Tm) of the fiber-forming water-insoluble resin is preferably 160 ° C. or higher, and more preferably 180 to 330 ° C. In the present invention, using a differential scanning calorimeter (DSC), the temperature is raised from room temperature to 300 to 350 ° C. according to the type of resin in a nitrogen atmosphere at a temperature rising rate of 10 ° C./min, and then immediately cooled to room temperature. The peak top temperature of the endothermic peak observed when the temperature was immediately raised again to 300 to 350 ° C. at a temperature rising rate of 10 ° C./min was defined as Tm. A colorant, an ultraviolet absorber, a heat stabilizer, a deodorant, a fungicide, an antibacterial agent, and other various stabilizers may be added to the fiber-forming water-insoluble resin at the spinning stage.

  The water-soluble resin refers to a melt-spinnable resin that can be dissolved or removed by heating or pressurizing with an aqueous solution such as water, an alkaline aqueous solution, or an acidic aqueous solution. In the present invention, “water-soluble” means that 10 g or more is dissolved in 100 g of water at 100 ° C., for example. The composite long fiber is converted to a fiber bundle of ultrafine fibers made of a fiber-forming water-insoluble resin by extracting and removing the water-soluble resin with water or an aqueous solution. Therefore, the solubility of the water-soluble resin in water needs to be greater than that of the fiber-forming water-insoluble resin. From the viewpoint of spinning stability, it is a resin that has a low affinity with the fiber-forming water-insoluble resin, and the resin has a melt viscosity smaller than that of the fiber-forming water-insoluble resin under the spinning conditions, or the surface tension is the fiber formation. The resin is preferably smaller than the water-insoluble resin. Examples of water-soluble resins that satisfy such conditions include polyvinyl alcohol resins, polyethylene glycol resins, modified polyesters obtained by copolymerizing sulfonic acid alkali metal salts such as sulfophthalic acid-modified polyesters, polyethylene oxide resins, Examples thereof include ethylene-vinyl acetate copolymers and styrene-acrylic copolymers, and water-soluble polyvinyl alcohol resins (PVA and generic names) such as polyvinyl alcohol homopolymers and polyvinyl alcohol copolymers are particularly preferable. By using a water-soluble resin, when the entangled nonwoven fabric structure is wet-heat treated, the water-soluble resin instantaneously swells and plasticizes, and hardly inhibits the shrinkage of the fiber-forming water-insoluble resin. A nonwoven fabric structure in which ultrafine fiber bundles are densely assembled in the process can be obtained. Artificial leather obtained from such a non-woven structure has good surface characteristics such as a dense surface and a rich texture, and physical properties such as wear resistance, light resistance, and form stability. is there.

  The PVA can be obtained by saponifying a polymer having a vinyl ester unit as a main constituent unit. 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 include vinyl versatate, and among these, vinyl acetate is preferable from the viewpoint of easily obtaining PVA.

  The PVA may be homo PVA or modified PVA, but it is preferable to use modified PVA from the viewpoint of melt spinnability, water solubility, and fiber properties. By appropriately selecting the type of copolymerization monomer used for modification, composite long fibers can be stably produced without reducing the water solubility of PVA. Examples of the comonomer include α-olefins having 4 or less carbon atoms such as ethylene, propylene, 1-butene, and isobutene from the viewpoints of copolymerizability, melt spinnability, and water solubility of fibers; and methyl vinyl ether Vinyl ethers such as ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether and n-butyl vinyl ether are preferred. 1-20 mol% is preferable, as for copolymer unit content in PVA, 4-15 mol% is more preferable, and 6-13 mol% is further more preferable. Furthermore, when the copolymer unit is ethylene, the fiber physical properties become high, and thus ethylene-modified PVA is particularly preferable. The ethylene unit content in the ethylene-modified PVA is preferably 4 to 15 mol%, more preferably 6 to 13 mol%.

  The PVA is produced by a known method such as a bulk polymerization method, a solution polymerization method, a suspension polymerization method, or an emulsion polymerization method. 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 the alcohol used as the solvent for the solution polymerization include lower alcohols such as methyl alcohol, ethyl alcohol, and propyl alcohol. For copolymerization, azo initiators such as a, a′-azobisisobutyronitrile, 2,2′-azobis (2,4-dimethyl-valeronitrile), benzoyl peroxide, n-propyl peroxycarbonate, etc. Alternatively, a known initiator such as a peroxide-based initiator is used. Although there is no restriction | limiting in particular about superposition | polymerization temperature, The range of 0 to 150 degreeC is suitable.

200-500 are preferable, as for the viscosity average polymerization degree (henceforth abbreviated polymerization degree) of the said PVA, 250-470 are more preferable, 300-450 are further more preferable. When the degree of polymerization is 200 or more, the melt viscosity shows a sufficiently high value for stable complexation, and when the degree of polymerization is 500 or less, the melt viscosity shows a sufficiently low value for easy ejection from the spinning nozzle. . Further, by using so-called low polymerization degree PVA having a polymerization degree of 500 or less, there is an advantage that the dissolution rate when removing with water or an aqueous solution is increased. The polymerization degree of PVA is calculated | required by following Formula according to JIS-K6726.
P = ([η] × 10 ³ /8.29) ^{(1 / 0.62)}
(P is the viscosity average polymerization degree, and [η] is the intrinsic viscosity measured in water at 30 ° C. after re-saponification and purification of PVA.)

  The saponification degree of the PVA is preferably 90 to 99.99 mol%, more preferably 93 to 99.77 mol%, further preferably 95 to 99.55 mol%, and particularly preferably 97 to 99.33 mol%. . When the degree of saponification is 90 mol% or more, the thermal stability is good, and it becomes difficult to undergo thermal decomposition or gelation during melt spinning. When the degree of saponification is 99.99 mol% or less, PVA is stable. It is possible to manufacture.

  The Tm of the PVA is preferably 160 ° C. or more, more preferably 170 to 230 ° C., further preferably 175 to 225 ° C., and particularly preferably 180 to 220 ° C. in view of spinnability. When the Tm is 160 ° C. or higher, a decrease in fiber strength of PVA due to a decrease in crystallinity can be avoided. Moreover, the thermal stability of PVA is good and the fiber forming property is good. When Tm is 230 ° C. or lower, the melt spinning temperature can be made sufficiently lower than the decomposition temperature of PVA, and ultrafine fiber-generating long fibers (such as sea-island long fibers) can be stably produced.

  The ratio of the water-soluble resin in the composite long fiber is preferably 5 to 60%, more preferably 10 to 50% of the fiber cross section in terms of area ratio. If it is less than 5%, the spinning stability of the composite long fiber is lowered, so that the industrial productivity is inferior. In addition, since the amount of water-soluble resin is small, friction and interference between the fiber-forming water-insoluble resins occur when the composite long fiber is shrunk by wet heat, and the desired shrinkage state and densification cannot be obtained. In addition, when the entangled nonwoven fabric structure is impregnated with an aqueous dispersion of a polymer elastic body and solidified, and then the water-soluble resin is removed, voids formed between the ultrafine fiber bundle and the polymer elastic body are not present. It will be enough. As a result, it becomes difficult to obtain a feeling of swelling, a sense of fulfillment, a fine surface feeling, and the like. On the other hand, if the ratio of the water-soluble resin exceeds 60%, the shape and distribution of the fiber-forming water-insoluble resin in the cross-section of the composite long fiber becomes irregular and the quality stability is inferior. Since the fiber-forming water-insoluble resin having shrinkage capacity is relatively insufficient when the heat and heat shrinkage is performed, the intended shrinkage state and densification cannot be obtained. In addition, the higher the ratio of water-soluble resin, the smaller the amount of ultrafine fibers in the ultrafine nonwoven fabric structure, so the amount of polymer elastic body necessary to impart form stability increases, and the water-soluble resin removed The burden on industrial production increases in terms of energy and cost required to recover the resin, and the burden on the global environment also increases. Therefore, it is preferable to reduce the ratio of the water-soluble resin within the above range.

  In the present invention, it is preferable to use the composite long fiber without cutting. The long fiber is a fiber that is not intentionally cut, such as a short fiber (fiber length: 10 to 50 mm). The fiber length of the composite long fiber cannot be generally specified, but in order to achieve the effects of the present invention, it is preferably 100 mm or more, and unless it is technically manufacturable and physically cut, It may be several meters, several hundred meters, several kilometers, or more.

The composite long fiber can be produced by a known mixed spinning method, composite spinning method or the like using the water-soluble resin and the fiber-forming water-insoluble resin. In the present invention, it is particularly preferable to use sea-island long fibers in which the sea component is the water-soluble resin and the island component is the fiber-forming water-insoluble resin. The number of islands of the sea-island fiber is preferably 8 to 70, the cross-sectional area is preferably 70 to 350 μm ² , and the area ratio of the sea component to the island component is 5/95 to 60/40 in the cross section. Is preferred.

  A composite spinning die is used for spinning the sea-island type fibers. The compound spinning nozzle is composed of a plurality of nozzle holes arranged in parallel or concentric circles at equal intervals. 8 to 70 island component polymer channels are uniformly arranged in each nozzle hole, and a sea component polymer channel is provided so as to surround the island component polymer channels. The sea component polymer and the island component polymer are continuously discharged from the base at a base temperature of 180 to 350 ° C. at a supply amount or a supply pressure such that the area ratio of the sea component and the island component in the cross section falls within the above range. While being cooled and solidified substantially by cooling air at any stage from just below the nozzle hole to the suction device described later, a high-speed air current is applied and the sea-island long fibers are uniformly pulled and thinned to the desired fineness. To do. The high-speed air current is applied so that the average spinning speed corresponding to the mechanical take-up speed in normal spinning is 1000 to 6000 m / min. Furthermore, while opening the sea-island type long fibers with a collision plate or airflow according to the texture of the obtained long fiber web, on the collecting surface such as a conveyor belt-like mobile net, from the opposite side of the net A long fiber web is formed by collecting and depositing while sucking.

  It is also preferable that the obtained long fiber web is subsequently subjected to pressure bonding while being partially heated or cooled by pressing, embossing or the like, depending on the degree of form stability required in the subsequent step. When the melt viscosity of the sea component polymer is smaller than the island component polymer, by heating or cooling at a temperature of about 60 to 120 ° C., without greatly damaging the cross-sectional shape of the sea-island long fibers constituting the long fiber web, The texture of the long fiber web can be sufficiently maintained in the subsequent steps. Furthermore, it is also possible to improve the shape stability of the long fiber web to a level that allows handling such as winding.

Generally used in conventional artificial leather production, the method of turning short fibers into fiber webs with card machines is not only for card machines, but also for applying oils and crimps to improve the card machine's passage, as prescribed. A series of large-scale equipment is required for cutting to a fiber length, conveying raw cotton after opening and opening, etc., and there are problems in terms of production speed, stable production, and cost. Further, the papermaking method also requires additional equipment such as cutting equipment, so that it also has the same problems as the above-mentioned method, and the basis weight of the nonwoven fabric is about 200 g / m ² at most. In contrast to the method using these short fibers, the production method of the present invention is performed in one continuous process from spinning to long fiber web formation, so that the equipment is very compact and simple, and the production speed and cost are reduced. Excellent. In addition, since a complex problem due to the combination of various processes and facilities does not occur, the stable productivity is excellent. In addition, the nonwoven fabric structure obtained from long fibers has sufficient restraint of the ultrafine fibers compared to the nonwoven fabric structure using short fibers in which the ultrafine fibers are restrained only by the entanglement between the fibers and the polymer elastic body, The artificial leather obtained by using this is excellent in form stability, mechanical strength, surface friction durability and the like.

  According to the manufacturing method of the present invention, it is possible to use a fiber having an extremely thin fiber diameter, which has been difficult with a method using a conventional card machine. Further, since it is not necessary to impart crimps and the fibers themselves are not bulky, an extremely dense nonwoven fabric structure can be stably obtained, and an extremely high-quality artificial material that has been impossible to achieve with conventional manufacturing methods. You can get leather.

In manufacturing a nonwoven fabric structure using conventional short fibers, a fiber diameter of a certain level or more suitable for a fiber opening device or a card machine is required. Specifically, the cross-sectional area needs to be 200 μm ² or more, and considering industrial stable productivity, fibers having a thickness of about 300 to 600 μm ² have been generally adopted. In the production method of the present invention, since the thickness of the fiber to be used is not limited by the equipment, even a very thin composite long fiber having a cross-sectional area of 100 μm ² or less can be used. To obtain a dense nonwoven structure, the cross-sectional area is preferably 70～350Myuemu ^2, the form stability in the subsequent step, the handling property is also taken into account 80～300Myuemu ² is more preferable. By using the composite long fibers having such a cross-sectional area, the obtained long fiber web can be obtained in any cross section parallel to the thickness direction per unit area of the cross section of the composite long fibers substantially orthogonal to the cross section. A fiber distribution state in which the number (existence density) is preferably 100 to 600 pieces / mm ² , more preferably 150 to 500 pieces / mm ² , is obtained. Can be obtained.

  When the basis weight and thickness of the long fiber web obtained as described above are insufficient, adjustment is performed by wrapping or stacking so as to obtain a desired basis weight and thickness. When the morphological stability and denseness of the composite long fibers are insufficient, or when adjusting the orientation of the composite long fibers in the thickness direction, the entanglement treatment is performed by a known method such as a needle punch method. Thereby, the composite long fibers which comprise a long fiber web, especially the composite long fibers in the different long fiber web layer by which the wrapping and stacking were carried out are entangled three-dimensionally. Needle punching is performed by appropriately selecting various processing conditions such as the type of needle (shape and count, barb shape and depth, number and position of barbs, etc.), the number of needle punches, and the needle punch depth.

  As the type of needle, those similar to those used in the production of conventional artificial leather using short fibers can be used. However, it is preferable to mainly use the needle described later in order to obtain the effects of the present invention.

  The size of the needle blade (the part where the needle tip barb is formed) is No. 30 (height if the cross-sectional shape is an equilateral triangle, and the diameter is about 0.73 to 0.75 mm if it is circular) It is preferably thinner, more preferably No. 32 (about 0.68 to 0.70 mm) to No. 46 (about 0.33 to 0.35 mm), more preferably No. 36 (height 0.58 to 0.60 mm). ) To 43 (height is about 0.38 to 0.40 mm).

  Barb depth is the height from the deepest part of the barb to the tip of the barb and refers to the combined height of the kick-up and the throat depth. The barb depth is not less than the diameter of the composite long fiber, and preferably not more than 120 μm. The barb depth is preferably 1.7 to 10.2 times the diameter of the composite long fiber, and more preferably 2.0 to 7.0 times.

  The number of barbs may be selected so as to obtain a desired entanglement effect in the range of 1 to 9, but the needles used mainly (the needles used for punching of 50% or more of the number of punches described later) The number is preferably six. In the case of having a plurality of barbs, the distance from the needle tip of each barb may be different or the same, but it is preferable that the needles used mainly for the entanglement process are different.

The total number of punches of the needle is preferably 800 to 4000 punch / cm ² , more preferably 1000 to 3500 punch / cm ² . The number of punches with a needle having a plurality of barbs equidistant from the tip is preferably about 300 punch / cm ² or less, and more preferably about 10 to 250 punch / cm ² or less. If the total number of needle punches is less than 800 punches / cm ² , densification and entanglement are insufficient. When it exceeds 4000 punches / cm ² , damage such as cutting and cracking of the composite long fiber increases. When the damage of the composite long fiber is particularly severe, the shape stability of the nonwoven fabric structure is greatly lowered and the denseness may be lowered.

  The needle punch depth is preferably set to such a depth that at least the most advanced barb penetrates the long fiber web. Moreover, it is preferable not to penetrate all barbs. For example, when using 6 barb needles, a needle punch depth that preferably does not penetrate 2 to 5 and more preferably 3 to 4 barbs through the long fiber web is preferable.

  In order to suppress damage to the fiber due to the needle punching process and to suppress charging and heat generation caused by the strong friction between the needle and the fiber, 1 is performed at any stage after the long fiber web manufacturing process and before the entanglement processing process. It is preferable to provide seeds or two or more oil agents. As the application method, known coating methods such as spray coating method, reverse roll coating method, kiss roll coating method, and lip coating method can be adopted, among which the spray coating method is non-contact with the long fiber web. In addition, a low-viscosity oil agent that penetrates into the long fiber web in a short time can be used, which is preferable.

The basis weight of the entangled nonwoven fabric structure obtained as described above is preferably 100 to 2000 g / m ² , and the average apparent density is preferably 0.1 to 0.3 g / cm ³ , more preferably 0. .15 to 0.25 g / cm ³ . Further, in an arbitrary cross section parallel to the thickness direction of the entangled nonwoven fabric structure, the number (existence density) per unit area of the cross section of the composite long fiber substantially orthogonal to the cross section is preferably 350 to 750 / cm ^2. It is.

  In order to obtain a more precise structure, the entangled nonwoven fabric structure may be subjected to wet heat shrinkage treatment with hot air, hot water, steam or the like. Moreover, it is also preferable to perform a press process in addition to an entanglement process or a wet heat shrink process. The press process may be performed before or after the entanglement process, or may be performed simultaneously with the entanglement process and the press process. Since the shrinkage state becomes non-uniform when performed simultaneously with the wet heat shrinkage treatment, the press treatment is preferably carried out before or after the wet heat shrinkage treatment.

  In the wet heat treatment, the entangled nonwoven fabric structure is thermally contracted so as to have a desired density in a high-temperature and high-humidity atmosphere. For heat shrink treatment, it is preferable that the composite long fiber is composed of a water-soluble resin and a heat-shrinkable fiber-forming water-insoluble resin. The conditions for the wet heat shrinkage treatment are not particularly limited as long as at least the fiber-forming water-insoluble resin shrinks sufficiently and the water-soluble resin swells and plasticizes but does not elute. For example, a method of introducing a saturated water vapor continuously into an atmosphere controlled at a temperature of 65 to 100 ° C. and a relative humidity of 70 to 100%, and a water-soluble resin swells and plasticizes in the entangled nonwoven fabric structure. After or while applying a sufficient amount of water, the entangled nonwoven fabric structure is heated by any of the following methods to shrink the fiber-forming water-insoluble resin and swell the water-soluble resin. A plasticizing method is preferred.

  As a method of heating the entangled nonwoven fabric structure to which moisture has been applied, a method of introducing it into an atmosphere controlled to a desired temperature, a method of causing air at a desired temperature to act directly on the entangled nonwoven fabric structure, or infrared rays, etc. A preferred example is a method in which the temperature of the entangled nonwoven fabric structure is increased to a desired temperature by the electromagnetic wave. If the area of the entangled nonwoven fabric structure is large, spots are likely to occur in the heat-shrinked state due to the influence of its own weight, etc., so it is heated to different temperatures depending on the length and width positions of the entangled nonwoven fabric structure. It is also preferable to adjust the starting point of contraction and the contraction speed.

In addition to the above-described entanglement treatment and wet heat treatment, press treatment is adopted as necessary prior to the impregnation treatment of the polymer elastic body described later in order to make the entangled nonwoven fabric structure dense. It is also preferable to do this. For example, when the target density is about 1000 to 1200 pieces / mm ² , the composite long fiber may be pressed after being densified to about 600 to 900 pieces / mm ² by wet heat treatment. . As a press treatment method, a method of pressing in the wet state after the wet heat treatment, a method of pressing in the dry state after the wet heat treatment, a method of pressing in a state where some moisture remains without being completely dried Etc. In addition, before the temperature of the wet heat shrinkage treatment or the drying treatment is lowered, the pressing process is performed while solidifying the softening component at a temperature lower than the surface temperature of the entangled nonwoven fabric structure, and the temperature is higher than the surface temperature of the entangled nonwoven fabric structure. Examples thereof include a method of softening the components and performing a press treatment while evaporating the contained water. When a composite long fiber whose softening temperature of the water-soluble resin is lower than the softening temperature of the fiber-forming water-insoluble resin is preferably 20 ° C. or more, more preferably 30 ° C. or more, the combined effect of the heat shrink treatment and the press treatment becomes greater. . Moreover, it can fix in the state which smoothed the surface of the entangled nonwoven fabric structure more by the press process. When the surface of the entangled nonwoven fabric structure is smooth, the amount of grinding in the raising process such as buffing later can be further reduced.

The presence density of the entangled nonwoven fabric structure obtained by wet heat treatment and press treatment as described above is preferably 1000 to 3500 pieces / mm ² , and the density is preferably 0.34 g / cm ³ or more. 0.34 to 0.85 g / cm ³ is more preferable.

  The entangled nonwoven fabric structure after the wet heat treatment and / or press treatment is impregnated with an aqueous dispersion of a polymer elastic body as necessary. The composite long fiber may be impregnated before being ultrafine, or may be impregnated after being ultrafine. Since the environmental load is small, it is preferable to use an aqueous emulsion of a polymer elastic body.

  As the polymer elastic body, any of those conventionally used for base materials for artificial leather can be adopted. Specific examples include polyurethane elastomers, acrylonitrile elastomers, olefin elastomers, polyester elastomers, and acrylic elastomers. Preferred are polyurethane elastomers and acrylic elastomers.

  Examples of the polyurethane elastomer include at least one polymer polyol having an average molecular weight of 500 to 3000 selected from polyester diol, polyether diol, polyether ester diol, polycarbonate diol, 4,4′-diphenylmethane diisocyanate, isophorone diisocyanate, hexamethylene. At least one polyisocyanate selected from aromatic, alicyclic, and aliphatic diisocyanates such as diisocyanate, and at least one active hydrogen atom having two or more active hydrogen atoms such as ethylene glycol and ethylenediamine. Examples include various polyurethane elastomers obtained by polymerizing a low molecular weight compound at a predetermined molar ratio by a one-step or multi-step melt polymerization method, bulk polymerization method, solution polymerization method, etc. . The content of the polymer polyol component in the polyurethane elastomer is preferably 15 to 90% by mass.

As the acrylic elastomer, the homopolymer has a glass transition temperature in the range of −90 to −5 ° C., and preferably a non-crosslinkable monomer such as methyl acrylate, n-butyl acrylate, isobutyl acrylate, The glass transition temperature of at least one soft component selected from isopropyl acrylate, n-hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and the like is in the range of 50 to 250 ° C. A monomer which is preferably non-crosslinkable, for example, at least one hard component selected from methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, cyclohexyl methacrylate, (meth) acrylic acid, etc. Monofunctional or polyfunctional ethylenic unsaturation that can form structures Compound or compound capable of reacting with ethylenically unsaturated monomer unit introduced into polymer chain to form crosslinked structure, for example, ethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, polyethylene glycol Examples thereof include various acrylic elastomers obtained by polymerizing at least one crosslinkable and ethylenically unsaturated monomer selected from di (meth) acrylate and 1,4-butanediol di (meth) acrylate.

  The content of the polymer elastic body in the aqueous dispersion of the polymer elastic body is preferably 0.1 to 60% by mass. The aqueous dispersion of the polymer elastic body has a heat-sensitive gelling agent, a colorant such as a dye or a pigment, a coagulation regulator, an antioxidant, an ultraviolet absorber, a fluorescent agent, an antibacterial agent as long as the effects of the present invention are not impaired. Conventional artificial materials such as glazes, penetrants, antifoaming agents, lubricants, water repellents, oil repellents, thickeners, extenders, curing accelerators, foaming agents, water-soluble polymer compounds such as polyvinyl alcohol and carboxymethyl cellulose You may mix | blend the various additive currently used for leather manufacture. The amount of the elastic polymer contained in the entangled nonwoven fabric structure may be appropriately adjusted according to the mechanical properties, durability, texture, etc. required for the intended use. When the basis weight of the nonwoven fabric structure is 100, 1 to 80% by mass thereof is preferable, 2 to 60% by mass is more preferable, and 5 to 40% by mass is further preferable. When the content of the elastic polymer is less than 1% by mass, it is difficult to uniformly contain the elastic polymer. On the other hand, when the content of the polymer elastic body is more than 80% by mass, the entangled nonwoven fabric structure is dense, so that the texture is remarkably cured and the rubber feeling is enhanced. The aqueous dispersion of the polymer elastic body is preferably contained in the entangled nonwoven fabric structure so as to be 0.5 to 50% by mass (based on solid content) with respect to the ultrathinned nonwoven fabric structure.

  The aqueous dispersion of the polymer elastic body impregnated in the entangled nonwoven fabric structure is solidified by a conventionally known dry method or wet method to fix the polymer elastic body in the entangled nonwoven fabric structure. Solidification by the dry method is performed, for example, by treating the surface of the entangled nonwoven fabric structure with a heating device such as an infrared heater at a nonwoven fabric surface temperature of 70 to 100 ° C. for 60 to 300 seconds. Solidification by a wet method is performed by, for example, processing for 20 to 300 seconds in a non-woven fabric surface temperature of 60 to 90 ° C. in a humidity controlled atmosphere with a wet bulb temperature of 70 to 100 ° C. In order to completely fix the solidified polymer elastic body, it is also preferable to perform a curing treatment such as a heat treatment after removing the dispersion medium.

  Next, the water-soluble resin is removed from the composite long fiber constituting the elastic body-containing nonwoven structure or the entangled nonwoven structure not containing the polymer elastic body, and the composite long fiber is converted into a fiber bundle of ultrafine fibers. . As a method for removing the water-soluble resin, a non-solvent or non-decomposing agent for a fiber-forming water-insoluble resin is used. A method of treating a nonwoven fabric structure with a liquid that is also a decomposing agent and that is a solvent of a water-soluble resin or a liquid that is a decomposing agent is preferable. For example, when PVA is used as a water-soluble resin, it may be removed with warm water at a temperature at which PVA is soluble, and a compound containing the above-mentioned alkali metal sulfonate is copolymerized as the water-soluble resin. When using an easily alkali-decomposable modified polyester, it may be removed at a temperature at which the water-soluble resin dissolves using an alkaline decomposing agent such as an aqueous sodium hydroxide solution. By such a water-soluble resin removal treatment, the composite long fiber is transformed into a fiber bundle of ultrafine fibers made of a fiber-forming water-insoluble resin, and an ultrafine nonwoven fabric structure is obtained.

  As described above, in the present invention, the fiber bundle of ultrafine fibers is preferably formed by removing the water-soluble resin from the composite long fiber containing the water-soluble resin (multicomponent fiber containing the water-soluble resin). In addition to this, for example, at least part of directly spun ultrafine fibers (bundles), or one component is dissolved and removed from a multicomponent fiber made of only water-insoluble resin, or it is separated and separated between multicomponent resin layers. At least a part of the ultrafine fibers (bundle) obtained in this manner is coated with a water-soluble resin in order to improve the processability and suppress the restraint of the ultrafine fiber bundle by the polymer elastic body ( A bundle). When the water-soluble resin is dissolved and removed, it is easy to allow a water dispersion of a polymer elastic body to be applied in a later step to be present at the root of the napped surface by leaving a part of the water-soluble resin on the surface of the ultrafine fiber. This is preferable. The abundance ratio of the water-soluble resin is preferably 0.05% or more with respect to the ultrafine fiber.

The existence density in an arbitrary cross section parallel to the thickness direction of the ultrafine nonwoven fabric structure is preferably 1500 to 3000 pieces / mm ^{2, and} more preferably 2000 to 2700 pieces / mm ² . The basis weight of the ultrafine nonwoven fabric structure is preferably 120 to 1600 g / m ² .

In order to obtain an extremely high-quality raised artificial leather, the cross-sectional area of the ultrafine fiber bundle is preferably 700 μm ² or less. The cross-sectional area of 700 μm ² or less corresponds to an ultrafine fiber bundle fineness of about 10 dtex or less, for example, when the polymer constituting the ultrafine fiber is polyethylene terephthalate. When the microfine fiber napped to obtain a nubuck artificial leather having a dense surface feeling short, the cross-sectional area of the microfine fiber bundle is preferably 500 [mu] m ² or less, more preferably 400 [mu] m ² or less. The lower limit value of the cross-sectional area of the ultrafine fiber bundle is preferably 170 μm ² or more, more preferably 180 μm ² or more, and further preferably 190 μm ² or more. The number of ultrafine fibers in the ultrafine fiber bundle is preferably 8 to 70, more preferably 10 to 60, and even more preferably 12 to 45.

  In order to form a raised surface having an elegant appearance and touch, the fiber diameter of the ultrafine fiber is preferably 0.8 to 15 μm, more preferably 1.0 to 13 μm, and still more preferably 1.2. It is 10-10 micrometers, and it is especially preferable that it is 1.5-8.5 micrometers. When the fiber diameter of the ultrafine fiber exceeds 15 μm, the appearance quality of the napped-tone artificial leather is adversely affected, for example, spots may be generated on the napped color of the surface or the smoothness of the touch may be hindered. On the other hand, when the fiber diameter of the ultrafine fiber is less than 1.0 μm, the feeling of napping becomes dense, but the appearance quality and surface properties are adversely affected. For example, the nap color on the surface may become whitish, or surface physical properties such as pilling resistance and wear resistance may deteriorate.

  Next, if necessary, the ultrafine nonwoven fabric structure is sliced into a plurality of sheets parallel to the main surface, and at least one surface is raised to form napped fibers made of ultrafine fibers to obtain a napped nonwoven fabric structure. For the raising treatment, any known method such as buffing with sandpaper or knitted cloth or brushing can be used.

An aqueous dispersion of a polymer elastic body, preferably an aqueous emulsion, is applied to the raised surface of the raised nonwoven fabric structure, and then dried at 100 to 150 ° C. The polymer elastic body for coating is selected from the above-described polymer elastic bodies, and polyurethane elastomers and acrylic elastomers are preferable. In addition, a self-emulsifying polyurethane emulsion is preferable because it has a large effect of fixing the roots of napped hairs.
The concentration of the polymer elastic body in the coating aqueous dispersion is preferably relatively high, and more preferably 30 to 40% by mass. Within the above range, it is possible to prevent the applied aqueous dispersion from penetrating into the napped nonwoven fabric structure, and to prevent the polymer elastic body solidified after drying from covering the napped upper surface. . In general, when a polymer elastic body aqueous dispersion having a high concentration as described above is applied and dried, the polymer elastic body solidifies into a film and covers the napped upper surface, and the nap feeling (appearance, texture) is lost. . However, in the present invention, even when the concentration is high in the above range, the nap enters the napped gap and solidifies at the root of the napped and in the vicinity thereof, so the nap feeling is maintained.

The coating amount of the aqueous dispersion of the elastic polymer (solids) is preferably from 1 to 5 g / m ² with respect to the napped nonwoven structure surface, and more preferably from 3 to 5 g / m ² . Within the above range, the surface of the obtained napped-tone artificial leather is prevented from becoming rubber-like, and the napped is fixed to the nonwoven structure without impairing the feeling of napping, and surface properties such as pilling resistance are improved. The

  The aqueous dispersion of the polymer elastic body is applied by a known application method such as spray coating, gravure coating, kiss roll coating, reverse coating, or knife coating, but is preferably applied by gravure coating. As long as the application amount is within the above range, it may be applied to the entire surface of the napped non-woven fabric structure, or may be continuous (for example, linear, belt-like, lattice-like, etc.) or discontinuous (for example, linear) , Broken lines, dots, spots, etc.) and may be applied in a regular or irregular shape. After application, the napped-tone artificial leather of the present invention is obtained by drying at 100 to 150 ° C. by a known drying method and solidifying the aqueous dispersion.

  In the napped artificial leather of the present invention, the polymer elastic body obtained by applying and solidifying the aqueous dispersion is in the form of a film and does not cover the napped upper portion, and is present at the base and in the vicinity thereof. In an arbitrary cross section parallel to the thickness direction of the napped-tone artificial leather, the polymer elastic body obtained from the aqueous dispersion exists as a continuous or discontinuous layer on the surface portion of the nonwoven fabric structure excluding the napped portion. Although the napping penetrates the polymer elastic body layer and protrudes to the outer surface, a part of the napping may be buried in the polymer elastic body layer.

  In general, it has been considered that when a polymer elastic body is applied to the napped formation surface after the napping treatment, the polymer elastic body solidified into a film covers the napped upper surface, and the nap feeling is lost. Therefore, in the conventional manufacturing method, after the polymer elastic body is applied to the surface, the coated surface is raised to form napped hairs. However, this method has a problem that the applied polymer elastic body falls off due to the raising process and the effect of pilling resistance is reduced. However, unlike the conventional recognition, when the polymer elastic water dispersion is applied to the napping formation surface of the napped nonwoven fabric structure obtained by the above-described production method of the present invention, the polymer elastic water dispersion becomes a gap between nappings. Therefore, it solidifies at the root of the napped and the vicinity thereof without solidifying into a film and covering the upper surface of the napped. As a result, the napping is fixed to the nonwoven fabric structure without losing the feeling of napping (appearance, texture), and surface properties such as pilling resistance are improved.

  The napped-tone artificial leather of the present invention may be dyed at any stage after the sea-island long fibers are transformed into ultrafine long fiber bundles. Dyes are selected from disperse dyes, reactive dyes, acid dyes, metal complex dyes, sulfur dyes, sulfur vat dyes, etc., depending on the type of fiber, and are usually used for dyeing traditional artificial leather such as padders, jiggers, circulars, and winds. It is dyed using the used dyeing machine. In addition to dyeing, if necessary, mechanical padding treatment in a dry state; relaxation treatment in a wet state using a dyeing machine or a washing machine; a softener, a flame retardant, an antibacterial agent, a deodorant, Functionality imparting treatment to apply water / oil repellent, etc .; Tactile sensation modifying treatment with silicone resin, silk protein-containing treatment agent, grip imparting resin, etc .; Resin other than those described above such as colorant, enamel coating resin, etc. It is also preferable to perform a finishing process such as a design imparting process. Since the napped-tone artificial leather of the present invention has a structure in which fiber bundles of extra-fine long fibers are gathered very densely, the relaxation treatment and the softening treatment in the wet state significantly improve the texture. For example, relaxing treatment in water containing a surfactant in a temperature range of about 60 to 140 ° C. has a feeling of flexibility and swelling that is not inferior to that of natural leather, and a sense of fulfillment with a dense structure is impaired. It is also possible to obtain no artificial leather.

  Next, embodiments of the present invention will be described with specific examples, but the present invention is not limited to these examples. In the examples, “part” and “%” relate to mass unless otherwise specified.

(1) Fineness, cross-sectional area Scanning electron microscope (magnification: several hundreds) was used to measure the cross-sectional area of composite long fibers (20), ultrafine fiber bundles (20) or ultrafine fibers (20) forming the nonwoven fabric structure. The average cross-sectional area was determined by measurement by a factor of about twice to several thousand times. The average fineness was calculated from the average cross-sectional area and the density of the polymer forming the fiber.

(2) Presence density With respect to an arbitrary cross section parallel to the thickness direction of the sample, using a scanning electron microscope (about 100 to 300 times), the observation area is about 0.3 to 0.5 mm ^{2 in} total. A continuous cross-sectional area was observed. In the observation field of view, the number of each cross section of the composite long fiber or ultrafine fiber bundle oriented almost perpendicular to the cross section is counted, and the total number is divided by the observation area, so that the composite exists per 1 mm ² of the sample cross section. The number of cross sections of the long fiber or ultrafine fiber bundle was determined. Such observation was performed on at least five places for one type of sample, and the smallest value was defined as the existence density of the sample.

(3) Density A sample was cut into a length of 10 cm and a width of 10 cm, and the weight was measured to two decimal places. Next, using a thickness measuring instrument with a load of 50 g / m ² , the average of the five thicknesses was calculated to obtain the density (g / cm ³ ).

(4) Surface abrasion property It measured according to the Martindale abrasion test measuring method prescribed | regulated to JISL1096. The condition is that the load is 9 kPa, the number of wear is 5,000 times, and the hair is collected in the measurement area. (The hairball shape is not limited to a spherical shape, and the napped fibers are in the shape of a line, flat, etc. Of the longest length of 0.5 mm or more among JIS L1076 woven and knitted pilling test method judgment table 2 (pilling judgment) Judgment grade was obtained by (based on Standard Photo 1).

Production Example Production of Water-soluble Polyvinyl Alcohol Resin 2100 kg of vinyl acetate and 31.0 kg of methanol were charged into a 100 L pressure reactor equipped with a stirrer, nitrogen inlet, ethylene inlet and initiator addition port, and the temperature was adjusted to 60 ° C. After raising the temperature, the system was purged with nitrogen by nitrogen bubbling for 30 minutes. Next, ethylene was introduced so that the reactor pressure was 5.9 kgf / cm ² . 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile) (initiator) was dissolved in methanol to prepare an initiator solution having a concentration of 2.8 g / L, and bubbling with nitrogen gas was performed. Replaced with nitrogen. After adjusting the polymerization tank internal temperature to 60 ° C., 170 mL of the initiator solution was injected to initiate polymerization. During the polymerization, ethylene was introduced to maintain the reactor pressure at 5.9 kgf / cm ² , the polymerization temperature at 60 ° C., and the above initiator solution was continuously added at 610 mL / hr. 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.
Subsequently, the unreacted vinyl acetate monomer was removed under reduced pressure to obtain a methanol solution of ethylene-modified polyvinyl acetate (modified PVAc). Saponification was performed by adding 46.5 g of a 10% methanol solution of NaOH to 200 g of a 50% methanol solution of modified PVAc prepared by adding methanol to the solution (NaOH / vinyl acetate unit = 0.10 / 1 ( Molar ratio)). The system gelled about 2 minutes after the addition of NaOH. The gelled product was pulverized with a pulverizer and allowed to stand at 60 ° C. for 1 hour to further promote saponification, and then 1000 g of methyl acetate was added to neutralize the remaining NaOH. After confirming neutralization with a phenolphthalein indicator, the mixture was filtered to give a white solid. 1000 g of methanol was added to the white solid, and the mixture was left to wash at room temperature for 3 hours. The above washing operation was repeated three times, and then the solution was centrifuged and left standing in a dryer at 70 ° C. for 2 days to obtain ethylene-modified polyvinyl alcohol (modified PVA). The degree of saponification of the obtained modified PVA was 98.4 mol%. Further, after the modified PVA was incinerated, a sample obtained by dissolving in acid was analyzed by an atomic absorption photometer. The content of sodium was 0.03 parts by mass with respect to 100 parts by mass of the modified PVA.

  In addition, n-hexane was added to the methanol solution of the modified PVAc, and then the precipitation-dissolution operation of adding acetone was repeated three times, followed by drying under reduced pressure at 80 ° C. for 3 days to obtain purified modified PVAc. When this modified PVAc was dissolved in d6-DMSO and analyzed using a 500 MHz proton NMR (JEOL GX-500) at 80 ° C., the content of ethylene units was 10 mol%. The above modified PVAc was saponified (NaOH / vinyl acetate unit = 0.5 (molar ratio)), pulverized, and allowed to stand at 60 ° C. for 5 hours to further promote saponification. The saponified product was extracted with methanol Soxhlet for 3 days, and the extract was dried under reduced pressure at 80 ° C. for 3 days to obtain purified modified PVA. It was 330 when the average degree of polymerization of this modified PVA was measured according to JIS K6726. The purified modified PVA was analyzed by 5000 MHz proton NMR (JEOL GX-500). As a result, the amount of 1,2-glycol bonds was 1.50 mol% and the content of 3-chain hydroxyl groups was 83%. Further, a cast film having a thickness of 10 μm was prepared from a 5% aqueous solution of the purified modified PVA. The film was dried at 80 ° C. under reduced pressure for 1 day, and then the melting point was measured by the method described above.

Example 1
The ethylene-modified polyvinyl alcohol as the sea component polymer and isophthalic acid-modified polyethylene terephthalate (content of isophthalic acid unit of 6.0 mol%) as the island component polymer were individually melted. The molten polymer is combined with the sea component polymer and the island in the cross section in a composite spinning nozzle having a large number of nozzle holes arranged in parallel, which can form a cross section in which 25 island component polymers of equal cross section are distributed in the sea component polymer It was supplied with a pressure balance such that the average area ratio of the component polymers was sea component / island component = 25/75, and was discharged from the nozzle hole at a die temperature of 250 ° C. The air-jet / nozzle-type suction device was used to draw and thin the sea-island long fibers of about 2.4 dtex, which were continuously collected on the net while being sucked from the back side. The amount of deposition was adjusted by adjusting the moving speed of the net, and was further pressed with an embossing roll kept at 80 ° C. at a linear pressure of 70 kg / cm to obtain a long fiber web having a basis weight of 30 g / m ² .
After spraying the oil agent on the surface of the long fiber web, the long fiber web was continuously folded using a cross wrapper device to form a layered long fiber web. Next, the layered long fiber web was three-dimensionally entangled by needle punching to obtain an entangled nonwoven fabric structure.
Next, water is spray-applied to both surfaces of the entangled nonwoven fabric structure, and then continuously in an atmosphere having a dry bulb temperature of 110 ° C. and a wet bulb temperature of 73 ° C. so that no tension acts in either the length direction or the width direction. And then subjected to wet heat shrinkage treatment. Subsequently, it dried with 120 degreeC drying machine, it pressed between metal rolls, the surface was smoothed, and the entangled nonwoven fabric structure of a fabric weight of 1000 g / m < ² > and a density of 0.66 g / cm < ³ > was obtained.
The obtained entangled nonwoven fabric structure was impregnated with an aqueous emulsion of polycarbonate polyurethane (solid content concentration 20% by mass) and pressed with a metal roll so that the pickup rate was 50%. Subsequently, the polyurethane aqueous dispersion was gelled in an atmosphere having a dry bulb temperature of 110 ° C. and a wet bulb temperature of 77 ° C., and cured with a dryer at 150 ° C.
Next, the modified polyvinyl alcohol, which is a sea component, is extracted and removed with hot water at 95 ° C. or higher so that 0.1% by mass remains with respect to the ultrafine fibers, and then dried with a dryer at 120 ° C. Thus, an ultrafine nonwoven fabric structure (polyurethane content (solid content): 11 mass% of the ultrafine nonwoven fabric structure) in which polyurethane was contained inside the nonwoven fabric structure composed of fiber bundles of ultrafine fibers was obtained. The basis weight of the ultrafine nonwoven fabric structure was 820 g / m ² .
The obtained ultrafine nonwoven fabric structure was sliced in parallel with the main surface and divided into two, and the divided surface was buffed with sandpaper to make the thickness uniform (thickness: 0.5 mm). Subsequently, the napping nonwoven fabric structure was obtained by raising and trimming the surface (the surface opposite to the divided surface) with sandpaper. Scanning electron micrographs of the surface and cross section of the napped nonwoven fabric structure are shown in FIGS.
Next, a high-concentration polycarbonate-based polyurethane emulsion (solid content concentration: 30% by mass) was applied to the raised and trimmed surface with a gravure roll and dried. The coating amount (based on solid content) was 4.2 g / m ² . Scanning electron micrographs of the surface and cross section after drying are shown in FIGS.
Next, after dyeing and drying with a disperse dye using a liquid dyeing machine, the hair was finished by brushing to obtain a napped artificial leather (thickness 0.55 mm, basis weight 270 / m ² ). As is clear from the comparison between FIGS. 2 and 4, the polymer elastic body obtained from the aqueous emulsion was present at the root of the napped and the vicinity thereof, and the upper surface of the napped was not covered with the polymer elastic body.
Since the polymer elastic body obtained from water-based emulsion is filled inside the ultrafine fiber bundle directly under the raised hair, the raised leather artificial leather has not only an elegant raised appearance similar to natural leather nubuck, but also texture and pilling resistance. All of the properties were extremely good. In addition, the surface abrasion property of napped artificial leather after applying a high-concentration polycarbonate-based polyurethane emulsion (solid content concentration: 30% by mass) with a gravure roll on the surface is the number of pillings after the Martindale abrasion test. It was 0, and the judgment grade was grade 5.

Comparative Example 1
Sea island type composite fiber staple (island component: sea component = 60: 40; fineness 4.0 dtex; fiber length 51 mm; crimp number 12 crimps / inch) is carded and cross-wrapped with island component polyethylene terephthalate and sea component polyethylene. Created the web. The web was subjected to a temporary entanglement treatment by needle punching at 40 punch / cm ² to obtain an entangled nonwoven fabric made of ultrafine fiber generating fibers having a basis weight of 300 g / m ² . Punching density from the entangled nonwoven fabric side by stacking the entangled nonwoven fabric and plain woven fabric, using a single barb felt needle at a piercing depth where the barb closest to the tip of the needle penetrates 6 mm from the outer surface of the plain fabric Needle punching was performed at 1200 punch / cm ² . The fiber which comprises an entangled nonwoven fabric penetrated the plain fabric, and the nonwoven fabric layer which consists of the fiber penetrated on the outer surface of the plain fabric was formed. Next, the non-woven fabric layer penetrates the plain fabric by needle punching at a punching density of 300 punch / cm ² from the nonwoven fabric layer side at a piercing depth where the barb closest to the tip of the needle does not penetrate the outer surface of the entangled nonwoven fabric. Part of the fibers constituting the fabric was folded back and re-entered into the plain fabric. By this treatment, the entangled nonwoven fabric and the plain fabric were entangled and integrated, and an entangled body for artificial leather having a basis weight of 370 g / m ² was obtained. The resulting entangled body for artificial leather was impregnated with a 15% dimethylformamide (hereinafter sometimes abbreviated as DMF) solution of polyether polyurethane, and then immersed in a DMF / water mixture bath to wet the polyurethane. It solidified. After removing the remaining DMF by washing with water, the sea component polyethylene was extracted and removed in a 85 ° C. toluene bath, and the remaining toluene was removed azeotropically in a 100 ° C. hot water bath, followed by drying. An artificial leather substrate with m ² and a thickness of 0.8 mm was obtained.
The surface of the non-woven fabric layer of the obtained artificial leather base was buffed twice with No. 180 sandpaper to make the thickness 0.7 mm while smoothing the surface. Subsequently, the surface of the entangled nonwoven fabric side was buffed twice with a No. 240 sandpaper and twice with a No. 400 sandpaper to obtain a raised artificial leather having a raised surface composed of ultrafine polyethylene terephthalate fibers.
Subsequently, the treatment after applying and drying a high-concentration polycarbonate-based polyurethane emulsion with a gravure roll on the raised and trimmed surface was carried out in the same manner as in Example 1.
Scanning electron micrographs of the surface and cross-section before gravure application of the aqueous emulsion are shown in FIGS. 5 and 6, and scanning electron micrographs of the surface and cross-section after gravure application and drying of the aqueous emulsion are shown in FIGS. Indicated. As can be seen from FIGS. 2 and 6, the napped state of the napped nonwoven fabric structure surface before the application of the aqueous emulsion was the same as in Example 1. However, as is clear from the comparison between FIGS. 6 and 8, the polymer elastic body obtained by applying a water-based emulsion to the napped forming surface and solidifying the napped root and the napped base in Example 1 without impairing the napped appearance. Although it existed in the vicinity, in Comparative Example 1, the film was solidified to cover the upper surface of the napped, and the napped appearance was lost.

Comparative Example 2
In Example 1, brushed brushing was performed on the surface that had undergone raising and hair treatment, without applying a high-concentration polycarbonate-based polyurethane emulsion. The obtained napped-tone artificial leather had an elegant napped appearance and a very good texture. However, as for the surface abrasion resistance, the number of pilling after the Martindale abrasion test was 5, and the judgment grade was 3-4 grade.

  The napped-tone artificial leather of the present invention has an elegant napped appearance and a good texture, and is excellent in surface properties, particularly pilling resistance, such as clothing, shoes, bags, furniture, car seats, gloves, bags, curtains, etc. It can be used to manufacture a wide range of artificial leather products.

Claims (7)

A non-woven fabric structure composed of a bundle of ultrafine fibers, and a napped artificial leather comprising a polymer elastic body arbitrarily contained in the non-woven fabric structure and having napped fibers of at least one surface The fiber bundle of the ultrafine fibers is formed by removing the water-soluble resin from the composite long fibers containing the water-soluble resin, and the napped root and the vicinity thereof are formed from an aqueous dispersion of a polymer elastic body. Napped-toned artificial leather with the resulting polymer elastic body. The napped-tone artificial leather according to claim 1, wherein the polymer elastic body obtained from the aqueous dispersion is present in an amount of 1 to 5 g / m ² on the surface of the nonwoven fabric structure. The napped-tone artificial leather according to claim 1 or 2, wherein the water-soluble resin is a water-soluble polyvinyl alcohol resin. The polymer elastic body obtained from the aqueous dispersion is present as a continuous or discontinuous polymer elastic body layer on the surface of the nonwoven fabric structure excluding the napping, and the napping penetrates the polymer elastic body layer. The napped-tone artificial leather according to any one of claims 1 to 3, which protrudes from the outer surface. The following steps (a) to (e):
(A) a step of making a composite long fiber containing a water-soluble resin into a long fiber web;
(B) entanglement treatment of the long fiber web to obtain an entangled nonwoven fabric structure;
(C) a step of extracting and removing a water-soluble resin from the composite long fibers constituting the entangled nonwoven fabric structure with water or an aqueous solution, and transforming the composite long fibers into a fiber bundle of ultrafine fibers to obtain an ultrafine nonwoven fabric structure ,
(D) a step of raising at least one surface of the ultrathinned nonwoven structure to form napped to obtain a napped nonwoven structure; and (e) applying an aqueous dispersion of a polymer elastic body to the napped surface. And then, solidifying the polymer elastic body to obtain napped artificial leather,
Method of napped-tone artificial leather containing The manufacturing method according to claim 5, wherein the water-soluble resin is a water-soluble polyvinyl alcohol resin. The coating amount to the napped nonwoven structure surface of the aqueous dispersion of the elastic polymer (solids) The production method according to claim 5 or 6 which is 1 to 5 g / m ^2.

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