JP4477511B2 - Method for producing artificial leather substrate - Google Patents

Description

  The present invention relates to a method for manufacturing an artificial leather substrate, and more particularly to a method for manufacturing an artificial leather substrate using a long-fiber nonwoven fabric.

  Artificial leather made of fiber aggregate and polymer elastic body is light, easy care, low price, etc., as a substitute for natural leather, shoes, balls, bags, furniture / vehicles, clothing, general materials and sports It is widely used for such as. In the conventional method for producing artificial leather, a fiber assembly such as a non-woven fabric is prepared, and this is impregnated with an organic solvent solution of a polymer elastic body and solidified.

  On the other hand, as a method for obtaining high-quality artificial leather, artificial leather using long fibers instead of conventionally used non-woven fabrics made of short fibers has been developed (for example, Patent Document 1). However, in artificial leather using long fiber nonwoven fabrics, unlike the short fibers, the fibers existing on the surface are continuous over a long distance, so the disturbance generated in that single fiber adversely affects the entire surface and the inside. There was a problem.

  In addition, there is a problem that a large amount of an organic solvent is used during the production of the polymer elastic body to be solidified, and at present, research for moving the impregnating liquid to an aqueous type is actively conducted. (For example, Patent Document 2)

  However, this method using an aqueous impregnating solution has a problem that the disturbance of the fibers is more emphasized because the polymer elastic body solution migrates along the direction in which each individual fiber exists. . In the organic solvent type, the polymer elastic body is solidified by the substitution (extraction) of the solvent with water, and the movement of the polymer elastic body itself is small, whereas in the aqueous type, the polymer elastic body is moved by the movement of water (evaporation drying). This is because solidification causes migration in which the polymer elastic body moves along the flowing direction of each individual fiber.

  When such migration occurs, especially in the silver-tone artificial leather with a film formed on the surface, when the surface of the obtained artificial leather is folded inward, large deep wrinkles occur, and the wrinkle marks are recovered. Therefore, there was a problem that large wrinkles remained on the toe portion when molded and worn as shoes. Also, balls are often evacuated during transportation, folded into a hemisphere, and air is introduced after transportation. However, artificial leather that has undergone migration has a problem that wrinkle marks remain at this time, resulting in a reduction in commercial value.

Japanese Patent Laid-Open No. 11-200209 JP 2000-290879 A

  The present invention has been made in view of the above-described problems of the prior art, and an object thereof is to provide an artificial leather substrate that can be efficiently manufactured and has excellent surface uniformity while using long fibers. It is in.

The production method of the present invention is a method for producing an artificial leather substrate comprising a long fiber nonwoven fabric and a water-based polymer elastic body, wherein a nonwoven fabric comprising a long fiber having a fineness of 0.5 to 0.001 dtex is produced. taking up continuously impregnated with the elastic polymer without, have in turn the row the steps of heat-sensitive coagulation, is in the process of heat-sensitive coagulation of normal pressure steam water or heated object introducing pressurized steam into the water Water droplets generated by means of direct contact and derived from the atmospheric water vapor are present in the air, and the temperature in the heat-sensitive coagulation zone is 80 ° C. or higher . In addition, it is preferable and this elastic polymer is a polyurethane.

  Further, the long fiber is a long fiber composed of two or more kinds of components that can be divided, and at least one component long fiber after the division has heat shrinkability, and the polymer constituting the long fiber is Polyester and polyamide are preferred.

  In addition, the long-fiber nonwoven fabric used in the present invention is produced by spinning, collecting on a net, laminating, entanglement, mechanically dividing, and performing hot water shrinking continuously without winding up. In addition, it is preferable that the hot water shrinking step is a step of capturing the long-fiber nonwoven fabric immersed and swimming in water on a water-permeable support.

  According to the production method of the present invention, there is provided a production method by which an artificial leather substrate excellent in surface uniformity can be obtained efficiently.

Hereinafter, embodiments of the present invention will be described in detail.
The present invention relates to a method for producing an artificial leather substrate comprising a long fiber nonwoven fabric and a polymer elastic body. Here, the long fiber nonwoven fabric is a nonwoven fabric produced from long fibers having a fineness of 0.5 to 0.001 dtex.

  As the long fibers used in the present invention, fibers used as conventional artificial leather or synthetic leather can be used, and synthetic fibers are preferable. Here, the long fiber means that a long fibrous form is maintained without being cut at several centimeters like a short fiber, and is a sufficiently continuous fiber without spinning after the polymer is spun. Say something.

  Examples of the polymer constituting the long fiber include polyamide components such as nylon-6, nylon-66, nylon-610, nylon-11, nylon-12, polyethylene terephthalate, polytriethylene terephthalate, polybutylene terephthalate, polypropylene terephthalate, polyethylene. Examples thereof include naphthalate and polyester components such as copolymer polyesters containing these as main components. And it is preferable that the long fiber used by this invention is a fiber which consists of these 2 or more types of polymers, and has the structure which can be divided | segmented.

  Furthermore, it is preferable that at least one polymer has heat shrinkability. As a preferred embodiment, the density of the nonwoven fabric can be increased by using fibers made of a polymer having heat shrinkability. Specific examples of the heat-shrinkable fiber preferably include, for example, polyethylene terephthalate, polytriethylene terephthalate, polybutylene terephthalate, or a copolyester containing these as a main component. In order to impart heat shrinkability, it is possible to take a technique such as adjusting the draw ratio and the drawing temperature during spinning, and it is particularly preferable to take means for adjusting the temperature and pressure of the ejector drawing immediately after spinning.

  In the present invention, among such long fibers, it is particularly preferable that the polymer constituting the long fibers is polyester and polyamide, and further, the long fibers are peeled split type composite fibers, and become ultrafine fibers after the fiber splitting. preferable. When a split split type composite fiber composed of two or more types of polymers has different heat shrinkage rates after splitting, the inter-fiber voids can be reduced during shrinkage, and the thin fibers are entangled alternately. This is more preferable because it has a suitable structure.

  The fineness of the fiber used in the present invention is essential to be 0.5 to 0.001 dtex, more preferably 0.3 to 0.08 dtex, and a higher quality artificial leather substrate can be obtained. . When the fineness is too large, not only the nonwoven fabric but also the texture of the artificial leather substrate becomes hard, which is not preferable.

  Further, these fibers may be mixed with several kinds of fibers instead of single. It is also preferable that not only long fibers but also short fibers are included in part. Various textures can be taken by containing short fibers.

  Nonwoven fabric made of long fibers having a fineness of 0.5 to 0.001 dtex used in the present invention is, for example, spun, collected on a net, laminated, entangled, mechanically divided, It is preferable that the step of shrinking is performed continuously without winding.

Hereinafter, this preferable method for producing a long-fiber nonwoven fabric will be described in more detail.
As a spinning method, a normal synthetic fiber spinning method can be applied. The collection on the net is a method in which long fibers obtained by spinning a polymer are directly collected on the net and laminated. The spun fiber is preferably stretched by an ejector in order to have appropriate strength and fineness. Moreover, it is also preferable as a fiber assembly composed of short fibers and long fibers by arranging short fibers in advance on the net. Since the present invention is a nonwoven fabric using long fibers instead of short fibers, the crimping and cutting steps are unnecessary, and therefore, it is possible to make a continuous process after the laminating step after spinning. The nonwoven fabric has an excellent texture.

In order to control the weight of the fiber assembly, the net is collected while moving, but the weight is determined by the net speed and the amount of spun fibers. The basis weight is preferably in the range of 20 to 60 g / m ² . If the amount is too large, variations tend to occur in the next layering process.If the amount is too small, not only is it too light and easily affected by wind, but it is necessary to increase the stacking speed, so the stacking is disturbed and the fiber assembly becomes uneven. Tend to be. In the next lamination step, it is preferable to employ a cross layer in order to make the long fiber nonwoven fabric uniform.

  Usually, in the manufacturing method of a long-fiber nonwoven fabric, in order to adjust the spinning speed of a fiber and the line speed of a subsequent process, it is once wound up in the collection process and lamination process of a fiber assembly. However, it is preferable that the long-fiber nonwoven fabric used in the present invention is continuously passed through these steps without being wound. The reason for this is that the fiber assembly at this stage has almost no entanglement, and is very delicate, which is likely to become non-uniform even by winds in the middle of the process. This is because there is a difference between a short fiber nonwoven fabric and a long fiber nonwoven fabric, in which a non-woven fabric composed of long fibers affects the entire nonwoven fabric. When there is no step of winding and unwinding as in the preferred embodiment of the present invention, the quality of the long-fiber nonwoven fabric, and thus the artificial leather that is the final product can be made extremely high.

  The fiber assembly laminated in this way is entangled and mechanically divided so that the fibers are entangled into a non-woven fabric to exhibit strength. As the entanglement method, needle punching or high-pressure water flow can be used. In order to obtain a dense and homogeneous nonwoven fabric, it is preferable to divide and entangle with a high-pressure water flow. Mechanical division is a method of dividing long fibers by applying mechanical force such as vibration, hitting, and shearing to the nonwoven fabric. Also here, in order to process as a series of steps without winding, it is preferable not to promote the division by the organic solvent or the organic compound. By omitting such a division promoting process, facilities such as an explosion-proof device and a solvent recovery device are not required. Although there is a difference in the easiness of division depending on the type and production method of the laminated fibers, basically, it is most preferable in terms of quality to employ a divider that combines vibration and shear on the basis of tapping.

  It is preferable that the non-woven fabric into which the fibers are divided subsequently passes through a step of hot water shrinkage. In the case of a nonwoven fabric, unlike a knitted or knitted fabric and the like, deformation due to an external force is large. In particular, when fibers that thermally shrink are used, slight disturbance of the long fibers is emphasized in the shrinking process, but the disturbance can be extremely reduced by continuously manufacturing the fibers.

  As a more preferred embodiment, when the long fiber nonwoven fabric is immersed and swimming in water, it is preferable to swim the nonwoven fabric by utilizing the buoyancy of water during immersion, and the nonwoven fabric can be uniformly contracted in all directions. The water temperature in the hot water shrinking step is preferably in the range of 50 to 95 ° C for densifying the nonwoven fabric, and particularly preferably in the range of 65 to 75 ° C. When the temperature is too low, shrinkage hardly occurs, and when the temperature is high, a large amount of water evaporates, resulting in a large energy loss. The processing time is suitably about 30 to 60 seconds.

The shrinkage rate of the nonwoven fabric is preferably 15 to 60%. More preferably, it is 30 to 45%. If the shrinkage rate is too small, the nonwoven fabric has a low density, and high-quality artificial leather cannot be obtained. Further, when the shrinkage rate is too high, the degree of freedom of the fiber with respect to bending or the like is lost. Moreover, in order for a nonwoven fabric and artificial leather to obtain isotropic properties, the difference in shrinkage between the vertical direction and the horizontal direction is preferably within 80%. These shrinkage rates can be adjusted by the shrinkage rate, the composition ratio, the entanglement degree, the temperature conditions in the shrinking process, the tension, and the like of the shrinking fibers in the nonwoven fabric. The apparent density of the nonwoven fabric after shrinkage is preferably 0.2 to 0.5 g / cm ³ , more preferably 0.25 to 0.45 g / cm ³ .

  Moreover, when making it immerse and swim in water, it is preferable to capture a long-fiber nonwoven fabric on the water-permeable support body in that state. The non-woven fabric that has been shrunk has buoyancy in the water, but the load in the vertical and horizontal directions, particularly in the machine direction of the manufacturing process, can be reduced to almost zero by pulling it out from the water as it is. As the water-permeable support, any material can be used as long as it can permeate excess water and support and move the nonwoven fabric. For example, a belt made of a net-like metal such as a net conveyor or a synthetic resin can be used. Preferably used. Furthermore, it is preferable to cool the nonwoven fabric on the support. For example, it can be quickly cooled by spraying low temperature water of 30 degrees or less. By doing in this way, the expansion-contraction on the support body of a nonwoven fabric can be suppressed, and generation | occurrence | production of the new stress on a support body can be suppressed. Moreover, since the nonwoven fabric temperature falls, the influence of the stress in a subsequent process can be suppressed to the minimum.

  Furthermore, it is preferable to be a production method in which water removal is continuously performed after the hot water shrinking step. Therefore, the support for capturing the nonwoven fabric is preferably water permeable. Thus, by removing the water | moisture content in a nonwoven fabric, the nonwoven fabric weight can be made low and the tension | tensile_strength in a process can be reduced more. As a method of removing moisture, a method of squeezing with mangle can be used, but in order to increase the dewatering efficiency and maintain the soft texture of the nonwoven fabric, it is preferable to perform dewatering under reduced pressure. At this time, by using a highly breathable material for the support, the air flow rate in the thickness direction of the nonwoven fabric can be increased and the dehydration can be further promoted. Since the non-woven fabric after dehydration becomes light, it can be easily moved to the next process with less tension. In order to completely remove moisture, it is preferable to perform heat drying after dehydration.

Incidentally, the underwater non-woven fabric, when drawn out of water as it is, contains 5 to 8 times the weight of the non-woven fabric fiber because it contains water. In particular, when the temperature of the water is high, the temperature of the non-woven fabric and the water aggregate does not decrease easily, so that the non-woven fabric stretches even with a slight tension. The physical properties such as degree are greatly different. For example, in the case of a non-woven fabric with a fiber weight of 1.4 m and a weight of 300 g / m ² , the load applied to the top of the non-woven fabric when it is pulled out from water to a height of 1 m is 300 g / m ² × 1.4 m × 1 m × 6 = 2520 g. This corresponds to a load of 1.8 kg weight per 1 m of nonwoven fabric.

  The long-fiber non-woven fabric obtained by such a preferred embodiment has surprisingly improved uniformity and excellent texture because there is no winding or unwinding step. In addition, it becomes a high-quality non-woven fabric with no anisotropy in the vertical and horizontal directions and excellent in isotropy, and can prevent the increase in the fiber orientation in the machine direction, which is the machine direction during production, and the increase in vertical fiber density spots. is there.

  The method for producing an artificial leather substrate according to the present invention comprises producing a nonwoven fabric composed of long fibers having a fineness of 0.5 to 0.001 dtex as described above, and then impregnating the polymer elastic body continuously without winding. It is essential to perform each step of solidification in order.

  Usually, in the manufacturing method of artificial leather, the manufacturing process of a nonwoven fabric and the process of impregnating a polymer elastic body and solidifying are divided. The line speed is different between the two processes. For example, if the polymer elastic body is solvent-based, the equipment must be explosion-proof. The non-woven fabric made of short fibers has not been considered to be disposed on the same continuous line because there is no problem in quality even if there are winding and unwinding steps between these steps.

  However, in artificial leather substrates using long-fiber nonwoven fabrics, it was found that fiber disturbances due to winding and unwinding caused by continuous fibers affected the inside of the nonwoven fabric and its surface, resulting in deterioration of quality. In the manufacturing method of the present invention, the nonwoven fabric is manufactured, and then the polymer elastic body is continuously impregnated without winding, and the steps of solidifying are sequentially performed, so that the surface uniformity is extremely high. A substrate could be manufactured.

  Examples of such a polymer elastic body used in the present invention include resins made of polymers such as polyester elastomer, polyurethane, NBR, SBR, and acrylic. Among these, polyurethane resins are preferable from the viewpoints of flexibility, strength, weather resistance, wear resistance, and the like. The polymer elastic body used in the present invention is preferably an aqueous dispersion or solution. By using an aqueous polymer elastic body, it is possible to easily adopt a continuous manufacturing process without adopting an explosion-proof specification.

Furthermore, it is preferable that the water-based polymer elastic body is a dispersion liquid or a solution having heat-sensitive coagulation property, which is dispersed or dissolved in a nonionic surfactant having a cloud point. In this case, the temperature at which the solidification characteristic of the polymer elastic body is manifested is preferably 30 ° C. or higher and 90 ° C. or lower. The temperature at which the solidification characteristics of the polymer elastic body are manifested is the temperature at which the impregnating liquid loses its fluidity and solidifies when the impregnating liquid containing various additives is heated while stirring. It is possible to adjust the coagulation temperature by adding an additive or the like.

  In addition, stabilizers such as antioxidants, UV absorbers, hydrolysis inhibitors, epoxy resins, melamine, etc. for the purpose of improving various durability such as light resistance, heat resistance, water resistance, and solvent resistance of polymer elastic bodies. A crosslinking agent such as a resin, an isocyanate compound, an aziridine compound, or a polycarbodiimide compound can be blended and used. Furthermore, various inorganic and organic pigments can be blended for the purpose of coloring. In addition, by adding various water repellents such as silicon and fluorine, and hydrophilic agents such as polyethylene glycol, the non-bonding structure between the fiber and the polymer elastic body is adjusted, and the drapeability of the fiber composite sheet is improved. Can be improved.

  The method for impregnating the long-fiber nonwoven fabric with the polymer elastic body may be any method as long as it is a conventional method. Although the arbitrary amount is employ | adopted for the adhesion amount (solid content) of a polymeric elastic body according to the objective, Preferably, it is 3-150 weight part with respect to 100 weight part of fiber assemblies. That is, the elastic body / fiber ratio R / F is preferably 3 to 150%, more preferably 5 to 100%. When the amount of attached polymer elastic body (solid content) is less than 3% by weight, the sense of fullness of the obtained sheet tends to decrease. On the other hand, if it exceeds 150% by weight, the resulting artificial leather substrate becomes hard and the texture of the artificial leather tends to decrease.

  From the balance of the texture and physical properties of the artificial leather, the thickness of the artificial leather substrate of the present invention is preferably in the range of 0.5 to 2.0 mm.

  Furthermore, as a method for solidifying the polymer elastic body, a conventionally known method is used. However, when the polymer elastic body is an aqueous solution or a water dispersion, heat-sensitive coagulation is preferable, for example, hot water, heating steam, high frequency And a solidification method by dielectric heating.

Here, the heat-sensitive coagulation method which is the most preferable embodiment will be described in more detail.
As a particularly preferred heat-sensitive coagulation method, after impregnating a long-fiber nonwoven fabric with an aqueous dispersion of a heat-sensitive coagulable polymer elastic body or an aqueous solution, water droplets derived from water vapor at normal pressure exist in the air. In addition, it is a method of heat-solidifying by treating in a heat-sensitive coagulation zone at 80 ° C. or higher. Here, the water droplet means a state generally referred to as steam, and is a state in which water vapor is observed as white as a minute water droplet when the water vapor is used below the boiling point. The normal pressure means that no pressure is applied, and it is preferably in the range of 0.9 to 1.1 atm. Here, when the water vapor is not normal pressure but pressurized water, when discharged from the pipe, the high-pressure water vapor expands along with the pressure drop, so the surroundings are cooled and some of the water vapor remains On the contrary, the rest is deprived of heat and becomes low-temperature water droplets (steam), and the diameter of the water droplets becomes large, which is not preferable. Such large water droplets are likely to condense inside the heat-sensitive coagulation zone, and the low-temperature water droplets that are condensed adhere to the fiber assembly impregnated with the polymer elastic body, so that the uncoagulated polymer elastic body is partially diluted. And spotted defects are likely to occur.

  Such normal-pressure water vapor can be generated, for example, by introducing pressurized water vapor into water or by bringing water into direct contact with a heated object (heater). In particular, the water vapor is preferably generated from the surface of the water. In this case, since water vapor is generated simultaneously from a wide area, the temperature and humidity in the zone can be more uniformly maintained. Such water vapor can be obtained by heating a water tank existing in the zone.

  Furthermore, it is most preferable that the steam is generated by blowing pressurized steam into the water. Unlike the case where high-pressure steam is released into the atmosphere, the generation of low-temperature water droplets having a large particle size can be suppressed by passing pressurized steam through water once. It is also optimal in terms of thermal efficiency. The pressurized water vapor is preferably 0.1 to 2 MPa, more preferably 0.2 to 0.6 MPa. As a means of heating water to generate atmospheric water vapor, there is a method of putting the heater directly into the water, but a vapor film or bubble gas film is generated between the heating surface and the water, and the efficiency of heat transfer Tend to decline.

  The temperature in the zone where such water vapor and water droplets are present is preferably 80 ° C. or higher from the viewpoint of efficient thermal coagulation. Furthermore, it is preferable that it is 85 degreeC or more, Most preferably, it is 90 degreeC or more. In order for water droplets to exist as steam in the space in the zone, the temperature in the zone is preferably not higher than the boiling point of water, more preferably not higher than 98 ° C., particularly preferably not higher than 95 ° C. In such a temperature range, when water vapor, which is a gas that exists simultaneously with water droplets (steam), condenses on the surface of the base material, latent heat is generated, and the temperature rise rate of the base material becomes faster and effective. Thermal coagulation is performed.

  As a heat-sensitive coagulation zone for more specific heat-sensitive coagulation, a water tank is installed in the heat-sensitive coagulation box that constitutes the zone, and high-pressure steam pressurized by a pipe-like pipe having a hole in it is formed. It is preferable to guide. The hole diameter is preferably 1 to 10 mm, and the interval is preferably 10 to 100 mm. It is preferable to increase the diameter of the hole in the portion far from the pressurized steam introduction side or to narrow the interval. By adopting such a distribution of holes, it is possible to supply water vapor uniformly to all parts of the water tank. It is also preferable that the pipe is composed of a plurality of pipes so as to narrow the interval between the discharge holes. Moreover, it is preferable that the discharge hole is not in the direction of the water surface but in the horizontal direction. More specifically, it is preferably within a range of 45 degrees and 30 degrees or less below the direction parallel to the water surface. Moreover, it is preferable that it is as deep as possible under the water surface, and it is preferable that it is 50 mm or less, Furthermore, it is the range of the depth of 150-1000 mm. By discharging in this way, the bubbles of water vapor become smaller and the bubbles pass through the hot water for a longer period of time, generating higher temperature, finer water droplets (steam). I can do it. If it is simply discharged from the pipe, the high-pressure water vaporizes and expands as the pressure drops, so the surroundings cool down, and some of the water remains in the water vapor state, but the rest loses heat and conversely cool water drops ( However, low-temperature water droplets are absorbed by the passage of bubbles through the hot water, and only high-temperature water droplets (steam) are generated from normal-pressure water vapor on the water surface.

  The heat-sensitive coagulation zone is preferably a heat-sensitive coagulation box that is insulated from the surroundings. Furthermore, it is preferable to include a water tank for generating steam in the box to be insulated. By doing so, heat loss can be suppressed. As such a heat-sensitive coagulation zone, for example, a structure in which high-pressure steam is introduced into a hot water bath installed in the lower part to generate high-temperature water droplets (steam), the temperature of the upper atmosphere, the temperature of the hot water bath The fiber aggregate impregnated with the polymer elastic body is guided by the guide roll, and the exit side of the fiber aggregate impregnated and solidified in the heat-sensitive coagulation zone is sealed with the outside and hot water. It is preferable that

  The temperature in the heat-sensitive coagulation zone can be any temperature as long as it is equal to or higher than the heat-sensitive coagulation temperature of the water-based polymer elastic body, and is more preferably set to a heat-sensitive gelation temperature of 10 ° C. or higher for more stable production. Also, the relative humidity is preferably high in order to use latent heat when water vapor condenses, and is preferably saturated. When the relative humidity is low, the polymer elastic body tends to become solid when solidified, and the drape and low resilience tend to deteriorate. In addition, it is preferable to avoid blowing steam directly into the heat-sensitive coagulation zone in order to maintain a humid atmosphere because it generates large-sized low-temperature water droplets and easily causes migration of the polymer elastic body before coagulation. The time during which the impregnated fiber aggregate is exposed to the heat-sensitive coagulation atmosphere depends on the heat-sensitive coagulation property of the polymer elastic water dispersion, but it may be such that the impregnation liquid is not squeezed out by bending with a guide roll. Preferably, it is 30 seconds to 120 seconds.

  It is preferable that the artificial leather base heat-coagulated in this way is further guided into hot water to complete the coagulation. The temperature of the hot water is set higher than the ambient temperature of the heat-sensitive coagulation zone, and the immersion time is preferably 20 seconds or more. Further, it is preferably in the range of 30 seconds to 5 minutes. This hot water can complete the coagulation and accelerate the crystallization of the polymer elastic body. Such a hot water bath is preferably installed at the outlet of the heat-sensitive coagulation zone and also serves to seal the inside of the zone.

  The artificial leather substrate guided to the outside from the heat-sensitive coagulation zone through hot water is dried by a hot air dryer or the like after excess water is removed by mangle drawing, vacuum dehydration or the like. When the cross section of the artificial leather substrate thus obtained is observed with an electron microscope, the impregnated polymer elastic body is uniformly distributed in the thickness direction.

  In the case of manufacturing in a continuous process as in the present invention, it becomes possible to manufacture an artificial leather substrate from spinning in just a few hours compared to the conventional method of dividing and manufacturing, which takes several days. It becomes an efficient manufacturing method.

  The artificial leather substrate obtained in the present invention is used for artificial leather by a conventionally known method. For example, it is made into a suede-like artificial leather by surface raising and dyeing, or a silver-like artificial leather by forming a colored film of a polymer elastic body such as polyurethane on the surface.

  The artificial leather obtained in this way is of excellent quality with excellent isotropic properties, and in particular, when it is made of artificial leather with a silver tone, it is bent inward and outward in the vertical direction as well as in the horizontal direction. In both cases, no large wrinkles are generated, only fine wrinkles finely dispersed on the surface are generated, and even when the bending is released, a high quality product that does not leave the wrinkles is obtained. The obtained artificial leather is used for sports shoes, shoes for women's and men's shoes, various ball applications for competition, industrial materials such as furniture, vehicles, interior materials, interior materials, bookbinding for notebooks and notebooks, clothing, etc. It can be preferably used for applications.

Hereinafter, the present invention will be described more specifically with reference to examples.
In addition, each item in an Example was measured with the following method.

(1) the area before shrinkage shrinkage and _{S 1.} Area after shrinkage is referred to as S _2. The shrinkage rate is obtained by the following calculation.
Shrinkage rate (%) = (S ₁ −S ₂ ) × 100 / S ₁

(2) Flexibility The degree of fiber orientation and density unevenness was evaluated by the flexibility in the vertical and horizontal directions.
A test piece of 25 mm × 90 mm in flexibility is prepared, and the lower 20 mm in the longitudinal direction is vertically held by a holder. Slide the holder while fixing the test piece so that it hits the center at a position of 20 mm from the tip of one end, and read the stress after 5 minutes from the recorder to fix the stress per 1 cm width. It was converted into flexibility. The unit is expressed in g / cm.

[Example 1]
Nylon-6 (intrinsic viscosity 1.1 in m-cresol) dried at 120 ° C. was fed to an extruder and melted. Separately dried at 160 ° C., polyethylene terephthalate (an intrinsic viscosity of 0.64 in o-chlorophenol) was melted with an extruder separate from the foregoing.

  Subsequently, the nylon-6 mixture melt flow was introduced into a spin block maintained at 275 ° C. at a conduit polymer temperature of 250 ° C., the polyethylene terephthalate melt flow at 300 ° C., and a rectangular shape having hollow forming discharge holes in a lattice arrangement. The two polymer melt flows are combined using a spinneret, combined and discharged at a rate of 2 g / min. / Hole, and an air pressure of 0.35 MPa (spinning speed converted from the discharge rate and composite fiber fineness is about 4860 m / min). Towed at high speed (ejector stretching).

  The pulled composite fiber is subjected to a high voltage application treatment at −30 kV, collided with a dispersion plate together with an air flow and opened, and a split split type composite fiber having a 16-split multi-layer laminating section (parent yarn fineness 4.4 dtex). ) Was collected on a net conveyor with a width of 1 m to obtain a web. Subsequently, the collected web was passed through a pair of upper and lower embossed calender rolls heated to 100 ° C. to obtain a heat bonded web.

Thereafter, the heat-bonded webs collected without being wound up were superposed with a cross layer so as to have a width of 170 cm, and then driven with a 1 barb needle to perform needle punching with a number of 1200 needles / cm ² and entangled. Next, separation treatment was performed using a striking type grinder to obtain a non-shrinkable ultrafine fiber nonwoven fabric having a basis weight of 210 g / m ² and a width of 170 cm.

  Next, the nonwoven fabric was immersed and swimmed in hot water at 70 ° C. for 60 seconds to be shrunk, collected on a net conveyor having a width of 190 cm, and pulled out from the hot water. In this process, the warp direction was 79 with respect to the length 100 before shrinkage, the horizontal direction was 76 with respect to the length 100 before shrinkage, and the area shrinkage rate was 40%. In addition, the water content at this time was 460%.

  Next, 13 ° C cold water is sprayed on the net conveyor to cool it, and then moisture is removed by a slit-type vacuum dehydrator located on the back side of the net conveyor, and dried with a hot air dryer at a moisture content of 120%. It was.

When the long-fiber nonwoven fabric was taken out and measured in this intermediate step, the basis weight was 350 g / m ² , the thickness was 1.0 mm, the apparent density was 0.35 g / cm ³ , the width was 129 cm, and there was no anisotropy in the vertical and horizontal diagonal directions. It was a high density non-woven fabric with excellent directivity. Since it was manufactured in a series of continuous lines from spinning, not only can it be produced in a short time, but also in terms of quality, there is a disturbance in the fibers due to partial pulling of the long fibers, compared to the conventional method of manufacturing with a divided line. No long-fiber nonwoven fabric with excellent texture.

The obtained long fiber non-woven fabric was continuously impregnated with a 9% dispersion of a heat-sensitive coagulation-type aqueous polyurethane (heat-sensitive coagulation temperature 60 ° C), and the excess dispersion on the surface was scraped off to form a heat-sensitive coagulation box. Was coagulated. The heat-sensitive coagulation box has a water tank with a width of 1600 mm, a width of 500 mm, and a depth of 300 mm at the bottom where there is no fiber assembly, and 0.29 MPa from two 1500 mm pipes located at a depth of 200 mm in the water tank. (3 kgf / cm ² ) of pressurized steam was supplied. Each pipe has a hole with a diameter of about 2 mm on the steam supply side at a pitch of about 20 mm, and a hole with a diameter of 3 mm on the end side. In the heat-sensitive coagulation box, the upper atmospheric temperature was controlled to 92 ° C. and the relative humidity was 99% by boiling water in a water tank installed at the lower part. Further, the outlet of the heat-sensitive coagulation box was sealed with hot water at 97 ° C., and the cloth path was set so that the impregnated non-woven fabric passed through the hot water tank of this sealed portion. The long-fiber nonwoven fabric impregnated with the dispersion is solidified in a 97 ° C hot water bath that seals its outlet by exposing it to a coagulation box with an atmospheric temperature of 92 ° C and a relative humidity of 99% for 1 minute. For 1 minute. Due to the solidification in the heat sensitive box, no polyurethane melted out in the hot water tank. Further, there was no color unevenness on the substrate, and no defects on the spots were observed. Then, after cooling, it was squeezed with a mangle roll and dried with a hot air dryer at 110 ° C. to obtain an artificial leather substrate having a thickness of 1.0 mm and an apparent density of 0.44 g / cm ³ . The fiber / polyurethane ratio of the obtained artificial leather base was 100: 30 by weight, and the cross section was observed with an electron microscope. The polyurethane was uniformly distributed in the thickness direction of the fiber composite.

(Making artificial leather)
On the other hand, on a release paper (R53 manufactured by Lintec Corporation), a thickening agent and 5 parts of a coloring agent were added to 100 parts of a 33% aqueous dispersion of polyurethane while stirring, and the mixture was adjusted to a viscosity of 8000 mPa · s. The film was coated at 90 g / m ² and dried at a temperature of 70 ° C. for 2 minutes and at 110 ° C. for 2 minutes. Furthermore, 150 g of a prepared liquid prepared by mixing 100 parts of a water-dispersible polyurethane adhesive (45% concentration), 5 parts of a colorant (black), and a thickener on the surface to adjust the viscosity to 5000 mPa · s. / M ² . Subsequently, after drying for 2 minutes at a temperature of 90 ° C., the artificial leather substrate obtained above was superposed and passed through a roll with a gap of 0.6 mm on the surface of a heated cylinder at a temperature of 110 ° C. and pressure bonded. Then, after leaving for 2 days in an atmosphere at a temperature of 60 ° C., the release paper was peeled off to obtain artificial leather. The obtained artificial leather has a longitudinal softness of 0.94 g / cm and a horizontal softness of 0.88 g / cm, and no large wrinkles are generated even if the surface is bent inward in both the vertical and horizontal directions. It was a thing.

  Soccer shoes and soccer balls were created using this artificial leather. The soccer shoes, when worn, became small wrinkles without generating large wrinkles on the toes, and were very similar to natural leather wrinkles. The soccer ball was deflated and folded into a hemisphere, and after one month, the air was put back into a sphere but no wrinkle marks remained.

[Comparative Example 1]
In the same manner as in Example 1, but not in a continuous process, it was wound once at the stage of a nonwoven fabric composed of long fibers, and then unwound and impregnated and solidified with a polymer elastic body to produce an artificial leather base. In terms of quality, fiber disturbance due to partial pulling of the long fibers occurred on the surface, and when the inside of the cross section was observed, the inner layer was disturbed.

Claims (9)

A method for producing an artificial leather base comprising a long fiber nonwoven fabric and a water-based polymer elastic body, wherein a nonwoven fabric comprising a long fiber having a fineness of 0.5 to 0.001 dtex is produced, and then continuously wound without being wound. impregnating the elastic polymer, it has in turn the row the steps of heat-sensitive coagulation, is generated by means of direct contact with the water to an object of the atmospheric pressure steam was or heated introducing pressurized steam into the water in the step of heat-sensitive coagulation A method for producing an artificial leather substrate, wherein water droplets derived from the atmospheric water vapor are present in the air, and the temperature in the heat-sensitive coagulation zone is 80 ° C. or higher . Process for producing an artificial leather substrate according to claim 1, wherein the elastic polymer is a polyurethane. The artificial leather substrate according to claim 1 or 2 , wherein a water tank is installed in a heat-sensitive coagulation box constituting the heat-sensitive coagulation zone, and high-pressure steam pressurized by a pipe-like pipe having holes formed therein is introduced . Production method. The method for producing an artificial leather substrate according to any one of claims 1 to 3, wherein an outlet side of the heat-sensitive coagulation zone is sealed with the outside by hot water .   The artificial fiber according to any one of claims 1 to 4, wherein the long fiber is a long fiber composed of two or more components that can be divided, and at least the one-component long fiber after the division has heat shrinkability. A method for producing a leather substrate.   The method for producing an artificial leather substrate according to any one of claims 1 to 5, wherein the polymers constituting the long fibers are polyester and polyamide.   2. A non-woven fabric comprising long fibers is produced by spinning, collecting on a net, laminating, entanglement, mechanically dividing, and hot-shrinking continuously without winding. The manufacturing method of the artificial leather base | substrate of any one of -6.   The method for producing an artificial leather substrate according to claim 7, wherein the hot water shrinking step is a step of capturing a long-fiber nonwoven fabric that is immersed and swimming in water on a water-permeable support.   An artificial leather, wherein a layer made of a polymer elastic body is provided on the surface of the artificial leather base according to any one of claims 1 to 8.