JP2006002286A - Manufacturing method of fibrous sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a fibrous sheet-like product that makes it possible to use ultrafine fibers that have been difficult to apply to artificial leather so far as fibers constituting an artificial leather substrate.
SOLUTION: On a woven or knitted fabric composed of ultrafine fiber-generating fibers in which at least one component is a water-soluble thermoplastic polyvinyl alcohol-based resin, from the ultrafine fiber-generating fibers in which at least one component is a water-soluble thermoplastic polyvinyl alcohol-based resin. When the long fiber nonwoven fabric sheet is laminated and needle punching is performed, the area shrinkage rate by needle punching is 30% or more, and the delamination strength of the fibrous sheet is 6 kg / 2.5 cm or more. A method for producing a fibrous sheet characterized by satisfying the above.
[Selection figure] None

Description

  The present invention uses an ultrafine fiber-generating long fiber nonwoven fabric in which at least one component is a water-soluble thermoplastic polyvinyl alcohol resin, and an ultrafine fiber generation-type woven or knitted fabric in which at least one component is a water-soluble thermoplastic polyvinyl alcohol resin. The present invention relates to a method for producing a fibrous sheet.

  Artificial leather has been recognized by consumers as being superior to natural leather in terms of lightness and ease of handling, and has become widely used in clothing, general materials, and sports.

  A conventional method for producing a general artificial leather is roughly as follows. In other words, ultrafine fiber-generating composite fibers made of two types of polymers with different solubility properties are stapled, formed into a web using a card, a cross wrapper, a random weber, etc., and the fibers are entangled with each other by a needle punch or the like to form a nonwoven fabric. After that, a flexible artificial leather can be obtained by applying a polymer elastic body such as polyurethane and removing one component in the composite fiber to make the fiber extremely fine.

  Here, if long fibers are used as the nonwoven fabric base, a series of large-scale equipment such as a raw cotton feeding device, a fiber opening device, a card machine, etc. is not required as a manufacturing method compared to a nonwoven fabric made of short fibers. As a result, there is an advantage that the strength is higher than that of the short fiber nonwoven fabric.

  Attempts have been made to use long fibers as a non-woven substrate for artificial leather, but products on the market use regular fibers of 0.5 decitex or more as the base for artificial leather with silver. However, artificial leather using ultrafine fibers has not been put on the market yet. This is the product represented by the difficulty in obtaining a stable non-woven fabric with a fabric weight, the handleability of the production of ultra-fine fiber generation type composite spun fiber, the thickness spots and the texture spots due to unevenness and strain of the composite long fibers, etc. Inferred to be due to unevenness. In fact, if the same manufacturing method as when short fibers are used is applied to ultra-fine long-fiber nonwoven fabrics, wrinkle defects occur in artificial leather in the ultra-fine fiber making process, dyeing process, etc., and it is difficult to produce a stable product. .

  As a method of eliminating such unevenness, a method of partially cutting long fibers and partially eliminating distortion (for example, see Patent Document 1) can be considered. There are cases where the contribution to the strong physical properties due to the connected fibers is reduced and the characteristics of the long fibers cannot be fully utilized. In addition, a method of introducing a reinforcing fabric such as a woven or knitted fabric to suppress fiber shape change (see, for example, Patent Document 2) can be considered. However, simply introducing a reinforcing fabric can cause the fiber to fall off due to friction or the like. Even if it is effective for the prevention effect, it may not resist the strain relaxation of the fiber and may cause a wrinkle defect.

Japanese Patent No. 3176492 JP-A 64-20368

  An object of the present invention is to provide a method for producing a fibrous sheet-like material that makes it possible to use, as a substrate for artificial leather, ultrafine fibers that have been difficult to apply to artificial leather.

As a result of intensive studies conducted by the present inventors to achieve the above-mentioned problems, the present invention has been achieved.
That is, the present invention provides an ultrafine fiber generation type in which at least one component is a water-soluble thermoplastic polyvinyl alcohol-based resin on a woven or knitted fabric comprising at least one component water-soluble thermoplastic polyvinyl alcohol-based resin. This is a method for producing a fibrous sheet-like material satisfying the following I and II when laminating long-fiber nonwoven fabric sheets made of fibers and performing needle punch treatment.
I. The area shrinkage ratio by needle punching is 30% or more II. The delamination strength of the fibrous sheet is 6 kg / 2.5 cm or more

The water-soluble thermoplastic polyvinyl alcohol resin preferably has a viscosity average polymerization degree of 200 to 500, a saponification degree of 90 to 99.99 mol%, and a melting point of 160 ° C to 230 ° C. Another embodiment of the present invention Is a method for producing an artificial leather base including a step of impregnating a polymer elastic body inside a fibrous sheet-like material obtained by any of the above methods, and a step of ultrafinening ultrafine fiber-generating fibers, Furthermore, it is an artificial leather produced from an artificial leather substrate produced by the above production method.

According to the method for producing a fibrous sheet-like material of the present invention, a fibrous sheet-like material suitable for an artificial leather substrate can be obtained, and a polymer elastic body is impregnated inside the sheet-like material to generate ultrafine fibers. An artificial leather substrate can be produced by making the mold fibers very fine. In addition, a suede or nubuck-like artificial leather can be obtained by fluffing the surface of the artificial leather substrate, and a resin is applied to the surface of the substrate or the surface is dissolved with heat or a solvent to form a resin layer. As a result, artificial leather with a silver surface can be obtained. These artificial leathers have natural leather-like fineness and a rich texture, are excellent in mechanical performance, and are excellent in softness and aesthetics. These artificial leathers can be processed into artificial leather products represented by shoes, balls, furniture, vehicle seats, clothing, gloves, baseball gloves, bags, belts or bags.

  An example of a specific means for achieving the present invention is preferably a single yarn fineness after ultrafinening using a water-soluble thermoplastic polyvinyl alcohol resin (hereinafter sometimes abbreviated as PVA) as one component. A non-woven fabric sheet is formed using filaments made of ultrafine fiber generating fibers capable of forming 0.0003 to 0.5 dtex ultrafine fibers, .Woven fabric composed of filaments using water-soluble thermoplastic polyvinyl alcohol-based resin capable of generating 5 decitex ultrafine fibers as one component, and multifilament yarns having a twist number of 10 to 650 T / M When the knitted fabric (referred to as woven fabric or knitted fabric) is piled up and needle punching treatment is performed, the area shrinkage ratio before and after the needle punching treatment is at least 3 % By a process of producing a fibrous sheet-like material by forming a monolithic structure by sufficiently increasing the entanglement of the long-fiber nonwoven fabric sheet itself and the entanglement of the long-fiber nonwoven fabric sheet and the woven or knitted fabric There is a method for manufacturing an artificial leather substrate including a step of impregnating a polymer elastic body in the interior and a step of ultra-fine ultrafine fiber generating fiber.

The term “integrated structure” as used herein means that not only the ultrafine fiber-generating fibers constituting the long-fiber nonwoven fabric sheet are entangled with each other while maintaining the form thereof, but also the ultrafine fiber-generating fibers are the structure of the ultrafine fiber-generating woven or knitted fabric. It is as long fibers as if the interlaminar peel strength is 6 kg / 2.5 cm or more in a state of being intertwined and randomly entangled, and the artificial leather substrate will cause structural destruction rather than peeling by peeling with a stronger stress. A structure in which a nonwoven fabric sheet and a woven or knitted fabric are integrated with each other.

In the present invention, the ultrafine fiber generation type fiber for obtaining the long fiber nonwoven fabric sheet composed of the ultrafine fiber generation type fiber is not particularly limited, and is obtained by using a method represented by a chip blend (mixed spinning) method or a composite spinning method. Can be selected as appropriate from sea-island-type cross-section fibers, multilayer laminated-type cross-section fibers, etc., but ultrafine fiber-generating long fibers comprising a water-soluble thermoplastic polyvinyl alcohol resin as a sea component and a water-insoluble thermoplastic resin as an island component. Preferably, the water-insoluble thermoplastic resin is not particularly limited, but polyesters such as polyethylene terephthalate (hereinafter referred to as PET), polytrimethylene terephthalate, polybutylene terephthalate (hereinafter referred to as PBT), polyester elastomer, and the like. Nylon 6, nylon 66, nylon 610, aromatic polyamide, polyamid Polyamide such as elastomer, polyurethane, polyolefin, polymer having a fiber forming ability, such as acrylonitrile is preferred. Among these, PET, PBT, nylon 6, nylon 66 and the like are particularly desirable from the viewpoint of the texture and practical performance of the processed product. These polymers preferably have a melting point of 160 ° C. or higher. When the temperature is lower than 160 ° C., the shape stability is inferior, which is not preferable from the viewpoint of practicality.
The melting point was raised to 300 ° C. in nitrogen using a differential scanning calorimeter (hereinafter referred to as DSC) at a heating rate of 10 ° C./min, then cooled to room temperature, and again a heating rate of 10 ° C. The temperature at the peak top of the endothermic peak indicating the melting point of the polymer when the temperature is raised to 300 ° C. per minute is employed.

In the present invention, a water-soluble thermoplastic polyvinyl alcohol-based resin is used as the sea component of the ultrafine fiber-generating fiber, but the use of the resin was selected in consideration of environmental pollution, shrinkage characteristics during dissolution and removal, and the like. Is. That is, by using such a polyvinyl alcohol-based resin, a large shrinkage occurs when it is dissolved and removed, the density of the artificial leather is increased, and the drapeability and texture of the artificial leather are very similar to those of natural leather. . As a mass ratio which occupies in the ultra fine fiber generation type | mold fiber before polyvinyl alcohol-type resin melt | dissolution removal, 5-70 mass% is preferable. More preferably, it is 10-60 mass%, Most preferably, it is 15-50 mass%. A preferred embodiment of the water-soluble thermoplastic polyvinyl alcohol resin itself will be described later.

The long fiber nonwoven fabric sheet comprising the ultrafine fiber-generating long fibers in the present invention can be efficiently produced by a method for producing a so-called spunbond nonwoven fabric directly connected to melt spinning, and includes a water-soluble thermoplastic polyvinyl alcohol resin and a water-insoluble material. The thermoplastic resin is melt-kneaded with separate extruders, the melted resin flow is guided to the spinning head through the composite nozzle and discharged from the nozzle hole, and the discharged composite fiber is cooled by a cooling device, and then air jet Using a suction device such as a nozzle, the fine fiber is pulled by a high-speed air stream at a speed corresponding to the take-up speed of the composite fiber of 1000 to 6000 m / min so as to achieve the desired fineness, and is deposited on the mobile collection surface. If necessary, it can be manufactured by partial crimping. The fineness of the resulting ultrafine fiber-generating fiber is preferably in the range of 1.0 to 5.0 dtex, and the basis weight of the long fiber nonwoven fabric sheet is preferably in the range of ^{20 to} 500 g / m ² from the viewpoint of process handleability. Moreover, it is preferable to set the number of islands of sea-island fibers so that the single fiber fineness after forming ultrafine fibers is in the range of 0.0003 to 0.5 dtex. If it is less than 0.0003 dtex, it is not preferable because the dyeability is difficult when it is made a suede-like artificial leather, and if it is more than 0.5 dtex, it is not preferable because it is inferior in flexibility and appearance quality when it is made.

  As the single fiber cross section of the ultrafine fiber generating fiber constituting the woven or knitted fabric and the resin used, the same selection as the ultrafine fiber generating fiber constituting the long fiber non-woven sheet can be made separately, but it was adopted for the long fiber non-woven sheet. It is preferable to use the same configuration as the above. That is, by using a water-soluble thermoplastic polyvinyl alcohol resin as a component to be removed and using a water-insoluble thermoplastic resin of the same series as the long-fiber non-woven sheet as the remaining component, the long-fiber non-woven sheet and the woven fabric are formed at the time of ultrafine fiber formation. The components to be removed of the knitted fabric can be removed at the same time, the shrinkage behavior during the process can be made uniform, and the occurrence of wrinkle defects due to the shape change can be avoided. In addition, considering the protrusion of the woven or knitted fiber on the surface of the long-fiber nonwoven fabric sheet, the single fiber fineness after the ultrafine fiber is preferably at the same level as the fineness of the ultrafine fiber constituting the long-fiber nonwoven fabric sheet, More preferably, it is in the range of 0.0003 to 0.5 dtex. As a result, the appearance and aesthetics of artificial leather are dramatically improved.

As the yarn constituting the woven or knitted fabric, a multifilament yarn is preferable, and the thickness of the multifilament yarn is preferably in the range of 50 to 150 dtex.

In the fibrous sheet-like product of the present invention, the woven or knitted fabric is present in the lower layer of the sheet cross section, but the twist number of the fibers constituting the knitted fabric is preferably 2500 T / m or less after the shrinkage treatment, and 1000 T / m. The following is more preferable, and 10 to 650 T / m is particularly preferable. By adopting the above-mentioned range, it is easy to move a part of the fibers constituting the woven or knitted fabric in the entanglement process step to the long fiber nonwoven fabric sheet side to facilitate the entanglement, and the long fiber nonwoven fabric layer and the woven or knitted fabric layer are entangled firmly. It is easy to obtain an integrated structure. On the other hand, if the number of twists is 10 T / m or more, the passability of the weaving and knitting process tends to be good.

The basis weight of the knitted fabric can be appropriately set depending on the purpose, but is preferably in the range of ^{20 to} 200 g / m ² after the ultrafine treatment, and most preferably in the range of 30 to 150 g / m ² . When the basis weight is less than 20 g / m ² , the form as a knitted fabric becomes very loose, and the fabric lacks stability such as misalignment. Further, when the basis weight exceeds 200 g / m ² , the knitted fabric structure becomes dense, and the fiber sheet-like material obtained with insufficient penetration of the fibers constituting the long-fiber nonwoven fabric does not proceed with high entanglement. It becomes difficult to produce an integrated structure.

The types of knitted fabrics are based on warp knitting represented by warp knitting, tricot knitting, lace knitting, and various knittings based on these knitting methods, or plain weaving, twill weaving, satin weaving, and their weaving methods. Although various textiles etc. are mentioned, it is not specifically limited to these. Among these woven fabrics, preferred are those using warps and weft yarns having a twist number of 10 to 650 T / m, and particularly preferred are warp and weft yarns having a twist number of 50 to 600 T / M. It is a woven fabric using the finished yarn.

  On such a woven or knitted fabric, the above-mentioned long-fiber nonwoven fabric sheet is superposed using a cross wrapper or the like, and then an oil agent is applied thereto, and then subjected to needle punching and integrated.

In the needle punching step, the long fiber nonwoven fabric sheet and the woven / knitted fabric are entangled so that the area shrinkage ratio of the laminate of the long fiber nonwoven fabric and the woven / knitted fabric before and after the needle punching is 30% or more, preferably 40% or more. When the area shrinkage rate is less than 30%, the apparent density of the fibers in the sheet of the fibrous sheet becomes low, and thus the long fiber nonwoven fabric in the process of manufacturing artificial leather, such as the ultrafine fiber forming fiber ultrafine process When the strain of the long fiber of the sheet potentially relieves the strain, it gives room for movement of the fiber, and the sheet is likely to be wrinkled, and the surface of the suede-like artificial leather lacks a dense feeling. Become.
Moreover, although the upper limit of the area shrinkage rate is not particularly set, it is preferably 80% or less in consideration of the physical shrinkage limit and the texture. Here, the area shrinkage rate represents a ratio obtained by dividing a value obtained by subtracting an area after shrinkage from an area before shrinkage by an area before shrinkage.

  In the needle punching process, it is necessary to entangle the long-fiber nonwoven fabric sheet and the woven or knitted fabric so that the delamination strength of the fibrous sheet-like material after needle punching is 6 kg / 2.5 cm or more. When the delamination strength is less than 6 kg / 2.5 cm, the entanglement between the long-fiber non-woven sheet and the woven / knitted fabric is insufficient, and the effect of suppressing the morphological change to the long-fiber non-woven sheet by the woven / knitted fabric is not sufficiently exhibited. In the manufacturing process of artificial leather, wrinkles are easily generated on the fibrous sheet. Further, the upper limit of the delamination strength is not particularly limited, but is preferably 30 kg / 2.5 cm or less from the viewpoint of the balance of the load and feel of the needle punching process.

  There are no particular limitations on so-called needle conditions such as the oil agent, the needle shape, the needle depth, the number of punches, etc. for satisfying such conditions, and it can be appropriately selected from known methods. For example, the needle shape is more efficient when the number of barbs is larger, but can be selected from 1 to 9 barbs within a range where needle breakage does not occur, and the depth is such that the needle needle barbs penetrate to the nonwoven fabric surface. In addition, it can be set within a range where the needle mark does not appear strongly. The number of punches may be increased or decreased depending on the selection of needle type, oil agent, etc. In any case, the artificial leather production of the present invention satisfies the area shrinkage rate of 30% or more and the delamination strength of 6 kg / 2.5 cm or more. It is necessary to secure process passability and shape stability, which are represented by wrinkle suppression.

  Next, PVA suitably used for the nonwoven fabric and woven or knitted fabric of the present invention will be described in detail. As the PVA used for the ultrafine fiber generating fiber constituting the long fiber nonwoven fabric sheet and the woven or knitted fabric of the present invention, those having a viscosity average polymerization degree (hereinafter simply referred to as polymerization degree) of 200 to 500 are preferable. The range of -470 is preferable and 250-450 is especially preferable. When the degree of polymerization is less than 200, the melt viscosity is too low and it is difficult to obtain a stable composite. When the degree of polymerization exceeds 500, the melt viscosity is too high, and it becomes difficult to discharge the resin from the spinning nozzle. By using so-called low polymerization degree PVA having a polymerization degree of 500 or less, there is an advantage that the dissolution rate is increased when dissolving with hot water.

The polymerization degree (P) of PVA here is measured according to JIS-K6726. That is, after re-saponifying and purifying PVA, it is obtained by the following equation from the intrinsic viscosity [η] measured in water at 30 ° C.
P = ([η] 10 ³ /8.29) ^{(1 / 0.62)}
When the degree of polymerization is in the above range, the object of the present invention can be achieved more suitably.

  The saponification degree of the PVA of the present invention is preferably 90 to 99.99 mol%, more preferably 93 to 99.98 mol%, further preferably 94 to 99.97 mol%, and 96 to 99.96 mol%. % Is particularly preferred. When the degree of saponification is less than 90 mol%, the thermal stability of PVA is poor, and not only satisfactory melt spinning cannot be performed by thermal decomposition or gelation, but also biodegradability is reduced. Depending on the kind of the polymerization monomer, the water solubility of PVA is lowered, and the composite fiber of the present invention may not be obtained. On the other hand, PVA having a saponification degree larger than 99.99 mol% cannot be produced stably.

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

  160-230 degreeC is preferable, as for melting | fusing point (Tm) of PVA used for this invention, 170-227 degreeC is more preferable, 175-224 degreeC is especially preferable, and 180-220 degreeC is especially preferable. When the melting point is lower than 160 ° C., the crystallinity of PVA is lowered and the fiber strength is lowered, and at the same time, the thermal stability of PVA is deteriorated, and there is a case where the fiber cannot be formed. On the other hand, when the melting point exceeds 230 ° C., the melt spinning temperature becomes high, and the spinning temperature and the decomposition temperature of PVA are close to each other, so that PVA fibers cannot be stably produced.

  The melting point of PVA is that when DSC is used, the temperature is raised to 300 ° C. in nitrogen at a heating rate of 10 ° C./min, cooled to room temperature, and then heated again to 300 ° C. at a heating rate of 10 ° C./min. It means the temperature at the peak top of the endothermic peak indicating the melting point of PVA.

  PVA can be obtained by saponifying a resin mainly containing vinyl ester units. 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 used in the present invention may be a homo-resin or a modified PVA into which copolymer units are introduced. However, from the viewpoint of melt spinnability, water solubility, and fiber properties, copolymer units are introduced. It is preferable to use modified PVA. The types of comonomer include ethylene, propylene, 1-butene, and isobutene having 4 or less α-olefins, methyl vinyl ether, and ethyl vinyl ether from the viewpoints of copolymerizability, melt spinnability, and water solubility of the fiber. , Vinyl ethers such as n-propyl vinyl ether, i-propyl vinyl ether and n-butyl vinyl ether are preferred. The unit derived from α-olefins having 4 or less carbon atoms and / or vinyl ethers is preferably present in PVA in an amount of 1 to 20 mol%, more preferably 4 to 15 mol%, and 6 to 13 mol%. Is particularly preferred. Further, when the α-olefin is ethylene, the fiber physical properties are high, and therefore, this is a case where a modified PVA into which ethylene units are introduced in an amount of 4 to 15 mol%, more preferably 6 to 13 mol% is used. .

  Examples of the PVA used in the present invention include known methods such as bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization. Among them, a bulk polymerization method or a solution polymerization method in which polymerization is performed without solvent or in a solvent such as alcohol is usually employed. Examples of alcohol used as a solvent during solution polymerization include lower alcohols such as methyl alcohol, ethyl alcohol, and propyl alcohol. Examples of the initiator used for copolymerization include a, a｀-azobisisobutyronitrile, 2,2｀-azobis (2,4-dimethyl-valeronitrile), benzoyl peroxide, n-propyl peroxycarbonate, and the like. And known initiators such as azo initiators and peroxide initiators. Although there is no restriction | limiting in particular about superposition | polymerization temperature, The range of 0 to 150 degreeC is suitable.

Artificial leather through the process of smoothing the surface of the fibrous sheet obtained as described above with a calender roll as necessary and impregnating the inside with a polymer elastic body, and the process of ultra-fine ultrafine fiber generating fibers A substrate can be produced. The polymer elastic body can be applied by dissolving the polymer elastic body in a solvent or dispersing it in a dispersion medium, impregnating the fiber sheet, and treating it with a non-solvent to wet solidify, or heat treatment or heat treatment. It can be carried out by applying water treatment or the like and then subjecting it to dry coagulation, hot water coagulation or thermal gelation treatment. Among these, the use of a water-dispersed resin is a preferable example because no organic solvent is used and the load on the environment is small.
In the case of a sea-island type fiber, the ultrafine fiber-generating fiber is made ultrafine by dissolving and removing a water-soluble thermoplastic polyvinyl alcohol resin as a sea component with hot water. Here, the water-soluble thermoplastic polyvinyl alcohol resin may be dissolved and removed before or after impregnation of the polymer elastic body.

  The artificial leather substrate thus obtained can be made into a suede-like artificial leather by fluffing, softening and dyeing the surface. As a method for fluffing, buffing using sandpaper or a needle cloth can be used. Moreover, it can also be set as the artificial leather of a tone with silver, or a tone with a half silver by the process of embossing, a softening process, dyeing | staining, etc. on a desired condition by a well-known method. These artificial leathers are free of wrinkles, have a natural leather-like solid feel, and have a drape property derived from long fibers, and are used as materials for products such as clothing, shoes, gloves, and sofas. Is preferred.

When manufacturing artificial leather using sea-island type long-fiber nonwoven fabric sheets, it is difficult to suppress movement due to fiber expansion and contraction at high temperatures such as sea component removal process, dyeing process, etc., resulting in irregular wrinkles on the entire sheet surface There are many. This tendency is particularly remarkable when the ratio of the binder resin is low, but it is integrated with a woven or knitted fabric having a certain shape retaining ability as in the present invention, and the generation of wrinkles is suppressed by suppressing the movement of the fibers. It becomes possible. In addition, the reinforcing effect of the woven or knitted fabric provides a flexible and high-quality artificial leather substrate that has high strength, high density, and excellent tear characteristics that cannot be obtained with a nonwoven fabric alone.
Example

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited to these examples.
The average fineness of the fibers is the density of the resin used for fiber formation and the area of the cross section of the fibers constituting the sheet, observed at a magnification of about several hundred to several thousand times using a scanning electron microscope. Is calculated from Further, the parts and% described in the examples relate to the mass unless otherwise specified.
The melting point of the resin was measured using a DSC (TA3000, manufactured by Mettler) measuring device in nitrogen at a heating rate of 10 ° C./min to 300 ° C., then cooled to room temperature, and again a heating rate of 10 ° C./min. The temperature at the top of the endothermic peak indicating the melting point of the resin when the temperature was raised to 300 ° C. was adopted.

Production Example 1
[Production of water-soluble thermoplastic polyvinyl alcohol resin]
A 100-liter pressurized reactor equipped with a stirrer, nitrogen inlet, ethylene inlet and initiator addition port was charged with 29.0 kg of vinyl acetate and 31.0 kg of methanol, heated to 60 ° C., and then bubbled for 30 minutes with nitrogen bubbling. Was replaced with nitrogen. Next, ethylene was introduced and charged so that the reactor pressure was 5.9 kg / cm ² . A solution of 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile) (hereinafter sometimes abbreviated as AMV) as an initiator in a concentration of 2.8 g / L in methanol was prepared, and nitrogen was added. Nitrogen substitution was performed by bubbling with gas. After adjusting the temperature inside the polymerization tank to 60 ° C., 170 ml of the initiator solution was injected to start polymerization. During the polymerization, ethylene was introduced to maintain the reactor pressure at 5.9 kg / cm, the polymerization temperature at 60 ° C., and AMV was continuously added at 610 ml / hr using the above initiator solution. . After 10 hours, when the polymerization rate reached 70%, the polymerization was stopped by cooling. After the reaction vessel was opened to remove ethylene, nitrogen gas was bubbled to completely remove ethylene. Next, unreacted vinyl acetate monomer was removed under reduced pressure to obtain a methanol solution of polyvinyl acetate. 46.5 g (polyvinyl acetate in acetic acid of polyvinyl acetate) was added to 200 g of polyvinyl acetate in methanol (100 g of polyvinyl acetate in the solution) adjusted to a concentration of 50% by adding methanol to the obtained polyvinyl acetate solution. Saponification was performed by adding an alkaline solution (NaOH in 10% methanol) having a molar ratio (MR) of 0.10 to the vinyl unit. About 2 minutes after the addition of alkali, the gelled system was pulverized with a pulverizer and allowed to stand at 60 ° C. for 1 hour to proceed with saponification, and then 1000 g of methyl acetate was added to neutralize the remaining alkali. . After confirming the end of neutralization using a phenolphthalein indicator, 1000 g of methanol was added to the white solid PVA obtained by filtration, and the mixture was left to wash at room temperature for 3 hours. After repeating the above washing operation three times, the PVA obtained by centrifugal drainage was left in a dryer at 70 ° C. for 2 days to obtain dry PVA.

  The saponification degree of the obtained ethylene-modified PVA was 98.4 mol%. Further, after the modified PVA was incinerated, the content of sodium measured by an atomic absorption photometer using a material dissolved in an acid was 0.03 parts by mass with respect to 100 parts by mass of the modified PVA. In addition, after removing the unreacted vinyl acetate monomer after the polymerization, a methanol solution of polyvinyl acetate obtained by precipitation in n-hexane and reprecipitation purification by dissolving with acetone was performed three times, followed by drying at 80 ° C. under reduced pressure for 3 days. To obtain purified polyvinyl acetate. When the polyvinyl acetate was dissolved in d6-DMSO and measured at 80 ° C. using 500 MHz proton NMR (JEOL GX-500), the ethylene content was 10 mol%. After saponifying the above methanol solution of polyvinyl acetate at an alkali molar ratio of 0.5, the pulverized product was allowed to stand at 60 ° C. for 5 hours to proceed saponification, followed by methanol soxhlet for 3 days, Ethylene-modified PVA purified by drying under reduced pressure at 80 ° C. for 3 days was obtained. It was 330 when the average degree of polymerization of this PVA was measured according to JIS K6726 of the usual method. The amount of 1,2-glycol bonds and the content of hydroxyl groups in the 3-linked hydroxyl group of the purified PVA were determined as described above from measurement with a 5000 MHz proton NMR (JEOL GX-500) apparatus. Met. Further, a cast film having a thickness of 10 microns was prepared by preparing a 5% aqueous solution of the purified modified PVA. The film was dried under reduced pressure at 80 ° C. for 1 day, and then the melting point was measured by the above-described method using DSC.

The water-soluble thermoplastic polyvinyl alcohol resin is used as a sea component, polyethylene terephthalate having an isophthalic acid modification degree of 6 mol% is used as an island component, and the number of islands per ultrafine fiber generating fiber is 25 islands. Using a melt compound spinning die, the mixture was discharged from the die at 260 ° C. so that the mass ratio of sea component / island component was 30/70. The ejector pressure was adjusted so that the spinning speed was 4500 m / min, and long fibers with an average fineness of 2.0 dtex were collected with a net to obtain a 30 g / m ² long fiber nonwoven fabric sheet.

Multi-filament yarn of 84 dtex-24 filaments composed of ultrafine fiber-generating fibers with 25 islands, with polyethylene terephthalate modified with 6 mol% isophthalic acid as island component and water-soluble thermoplastic polyvinyl alcohol resin as sea component ^On the plain woven fabric having a twist number of 550 T / m, a woven density of 105 × 84 pieces / inch, and a basis weight of 100 g / m ² , the above-mentioned equivalent of eight long fiber nonwoven fabric sheets are overlapped by a cross wrap method, Spray applied.

Next, using a 1-barb needle with a distance of 5 mm from the tip of the needle to the barb, needle punching of 3600 P / cm ² was alternately performed from both sides at a needle depth of 10 mm, and the woven fabric and the long fiber nonwoven fabric sheet were entangled. The area shrinkage due to this needle punching treatment was 50%, and the delamination strength of the fibrous sheet after needle punching was 9.5 kg / 2.5 cm.

The sheet-like material was pressed with a calender roll to obtain a fibrous sheet-like material having a smooth surface. The basis weight of this fibrous sheet was 650 g / m ² and the apparent specific gravity was 0.78. This fibrous sheet is impregnated with Superflex E-4800 (Daiichi Kogyo Seiyaku Co., Ltd.) as a water-based polyurethane emulsion, dried and cured, and then subjected to ultrafine fiber generation in hot water at 95 ° C. By dissolving and removing the water-soluble thermoplastic polyvinyl alcohol resin of the fiber, an ultrafine fiber bundle made of island components was developed to obtain an artificial leather substrate having a thickness of 0.7 mm. The average fineness of the ultrafine fibers was 0.05 dtex. Further, the mass ratio of polyurethane in the artificial leather substrate was 13%, and there was no wrinkle defect at all. The artificial leather base was raised by buffing and dyed with a disperse dye to obtain a suede-like artificial leather having a thickness of 0.7 mm. The obtained sheet was free of wrinkles, had a natural leather-like fullness and good lighting properties, and had strength properties suitable for applications such as interiors and car seats.

The above-mentioned water-soluble thermoplastic polyvinyl alcohol resin is used as a sea component, melt flow rate at 255 ° C .: polyamide of 10 is used as an island component, and the number of islands per fiber is 36 islands. Was discharged from the base at 255 ° C. so that the mass ratio of sea component / island component was 30/70. The ejector pressure was adjusted so that the spinning speed was 4500 m / min, and long fibers with an average fineness of 2.0 dtex were collected with a net to obtain a 30 g / m ² long fiber nonwoven fabric sheet.

^On a knitted fabric with a basis weight of 100 g / m ^{2 made} of 36 ultra-fine fiber-generating fibers having an island component of polyamide having the same composition as the fibers constituting the long-fiber nonwoven fabric sheet and a sea component of water-soluble thermoplastic polyvinyl alcohol resin. Further, 10 sheets of the above-mentioned long fiber nonwoven fabric sheet were overlapped by a cross wrap method, sprayed with a needle breakage preventing oil agent, and needle punching of 2400 P / cm ² was performed alternately from both sides. The area shrinkage due to this needle punching treatment was 45%, and the delamination strength of the fibrous sheet after needle punching was 8.0 kg / 2.5 cm.

The sheet-like material was pressed with a calender roll to obtain a fibrous sheet-like material having a smooth surface. The basis weight of this fibrous sheet was 540 g / m ² and the apparent specific gravity was 0.76. This fibrous sheet was impregnated with Superflex E-4800 (Daiichi Kogyo Seiyaku Co., Ltd.) as a water-based polyurethane emulsion, dried and cured, and then in a composite spun fiber in 95 ° C. hot water. The water soluble thermoplastic polyvinyl alcohol resin was dissolved and removed to express an ultrafine fiber bundle made of island components, and an artificial leather substrate having a thickness of 0.55 mm was obtained. The average fineness of the ultrafine fibers was 0.03 dtex. The mass ratio of polyurethane in the artificial leather substrate was 16%. This artificial leather base was raised by buffing and then dyed with a metal-containing dye to obtain a suede-like artificial leather having a thickness of 0.55 mm. The obtained sheet was free of wrinkles, had a natural leather-like fullness, good drapeability, and writing properties, and was a material suitable for applications such as clothing.

Comparative Example 1
Except not using a woven or knitted fabric, the fibrous sheet-like thing was produced only from the long-fiber nonwoven fabric sheet on the same needle punch conditions as Example 1. The obtained fibrous sheet was made into an artificial leather base by the same process as in Example 1. However, many wrinkles were formed in the process of dissolving and removing the water-soluble thermoplastic polyvinyl alcohol resin, and it could not be used as a product. It became a thing.

Comparative Example 2
In Example 1, a fibrous sheet was produced under the same conditions except that the number of needle punches was 280 P / cm ² . The area shrinkage due to this needle punching treatment was 23%, and the delamination strength of the fibrous sheet after needle punching was 1.0 kg / 2.5 cm. The obtained sheet-like material was made into an artificial leather base by the same process as in Example 1. However, a lot of wrinkles were generated in the process of dissolving and removing the water-soluble thermoplastic polyvinyl alcohol resin, and it was not able to withstand use as a product. became.

Comparative Example 3
A fibrous sheet was produced under the same conditions as in Example 1 except that the needle depth of the needle punch was 6 mm. The area shrinkage due to this needle punching treatment was 32%, and the delamination strength of the fibrous sheet after needle punching was 5.0 kg / 2.5 cm. The obtained sheet-like material was made into an artificial leather base by the same process as in Example 1. However, a lot of wrinkles were generated in the process of dissolving and removing the water-soluble thermoplastic polyvinyl alcohol resin, and it was not able to withstand use as a product. became.

Comparative Example 4
A fibrous sheet was produced under the same conditions as in Example 1 except that the sea component of the ultrafine fiber generating fiber was changed from water-soluble thermoplastic polyvinyl alcohol resin to polyethylene. When toluene is used to dissolve and remove polyethylene when it is used as an artificial leather base, the polyethylene terephthalate of the island component swells, increasing the elongation during the process and making it difficult to handle. The texture and lack of fulfillment were lacking.

Claims (4)

On a woven or knitted fabric composed of ultrafine fiber-generating fibers whose at least one component is a water-soluble thermoplastic polyvinyl alcohol resin, a long-fiber nonwoven fabric composed of ultrafine fiber-generating fibers whose at least one component is a water-soluble thermoplastic polyvinyl alcohol resin. A method for producing a fibrous sheet-like material, characterized in that when the sheets are laminated and subjected to needle punching, the following I and II are satisfied.
I. The area shrinkage ratio by needle punching is 30% or more II. The delamination strength of the fibrous sheet is 6 kg / 2.5 cm or more The method for producing a fibrous sheet-like material according to claim 1, wherein the water-soluble thermoplastic polyvinyl alcohol resin has a viscosity average polymerization degree of 200 to 500, a saponification degree of 90 to 99.99 mol%, and a melting point of 160 ° C to 230 ° C. . A method for producing an artificial leather substrate, comprising a step of impregnating a fibrous sheet obtained by the method according to claim 1 with a polymer elastic body and a step of ultrafinening an ultrafine fiber generating fiber. . The artificial leather base | substrate obtained by the manufacturing method of Claim 3.