JP2008121128A - Artificial leather and method for producing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an artificial leather using ultra fine fibers comprising polylactic acid which is a raw material originated from plants, thereby reducing the employment of petroleum raw materials. <P>SOLUTION: This artificial leather which comprises an interlaced fiber product prepared by integrally laminating a nonwoven fabric comprising ultra fine fiber bundles to a woven or knitted fabric and an elastic polymer impregnated in the interlaced fiber product is characterized by satisfying the following (1) to (3). (1) The ultra fine fibers comprise polylactic acid. (2) The strength of single fibers constituting the woven or knitted fabric is 2.0 to 4.5 cN/dtex. (3) The elastic polymer is partially fused to the outer peripheries of the ultra fine fiber bundles. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an artificial leather obtained by using a petroleum substitute as a part of raw materials constituting an artificial leather and suppressing the use of petroleum products. More specifically, the present invention relates to an artificial leather having natural leather-like fullness and flexibility and sufficient practical strength even when polylactic acid is used as a petroleum substitute.

  Artificial leather is recognized by consumers for its light weight, ease of handling, quality stability, etc., and is used in household goods such as shoes, bags and accessories, interiors such as sofa upholstery materials and vehicle interior materials. It is used as a substitute for natural leather in a wide range of applications such as fields and clothing. On the other hand, in recent years, from the viewpoint of global environmental conservation and oil replacement, these artificial leathers have also been required to reduce the environmental load and to remove oil. From such a background, artificial leather using plant-derived plastics is now being demanded as a substitute for petroleum.

  As a plant-derived plastic, polylactic acid obtained by degrading starch contained in various plants such as corn, banana, bamboo, seaweed, etc. into glucose with an enzyme and taking out lactic acid artificially is used as a representative example. It is attracting attention in terms of its heat resistance and strength. Polylactic acid can be melt-spun at a melting point of about 170 ° C., and the strength of the obtained polylactic acid fiber is comparable to that of polyester. Furthermore, polylactic acid fibers do not generate NOx or the like in the combustion gas during incineration, and the combustion heat is about 1/2 to 1/3 of polyethylene or polypropylene. And it is also attracting attention as biodegradability.

Under such circumstances, there have been many attempts to commercialize fiber structures made of polylactic acid, but using entangled non-woven fabrics composed of biodegradable ultrafine fiber bundles and polymer elastic bodies, At present, artificial leather having natural leather-like fullness and flexibility and sufficient practical strength has not yet been put on the market. For example, a shoe insole using a needle punched nonwoven fabric made of polylactic acid fiber has been proposed (see, for example, Patent Document 1). However, in this invention, since the short fiber is used and the polymer elastic body is not used, the strength of the nonwoven fabric is weak, and the dyeing process cannot be endured as it is. In addition, even if not dyed, the strength of the nonwoven fabric is insufficient, so it is necessary to laminate it with a reinforcing material such as a woven or knitted fabric through an adhesive, and the obtained sheet material has a poor sense of fullness. It is easy to become a paper-like thing.
On the other hand, in a sheet material obtained by impregnating a polyurethane binder into a nonwoven fabric obtained by using polylactic acid short fibers, card and needle punching treatment, raising and then dyeing with a disperse dye, The incorporated disperse dye is easy to peel off. Moreover, since the dyeing fastness is insufficient, it is necessary to reduce and wash under alkaline conditions. However, since polylactic acid fibers are easily hydrolyzed under alkaline conditions, it is difficult to obtain artificial leather sufficient as practical strength by such a method. In other words, when using polylactic acid fibers in the form of short fibers, it is difficult to obtain artificial leather that combines natural leather-like fullness and flexibility with sufficient practical strength, regardless of whether or not a urethane binder is used. There is a fact that it is not put on the market as a product after all.

In addition, a woven or knitted fabric using ultrafine fibers having a single yarn fineness of 0.01 to 1 dtex obtained from a sea-island cross-section composite fiber containing an aliphatic polyester having an melting point of 130 ° C. or higher as an island component has been proposed (for example, Patent Document 2), and further, a fiber structure excellent in black color development using a polylactic acid fiber composed of a blend of poly-L lactic acid and poly-D lactic acid and a method for producing the same are proposed (for example, And Patent Documents 3 and 4). However, these are all woven fabrics,
It relates to polylactic acid fiber structures that are substantially free of polymer binders, suitable for the manufacture of knitted fabrics. Artificial leather having a natural appearance could not be produced.

JP 2004-49725 A JP 2000-226734 A JP 2002-227034 A JP 2002-227035 A

  This invention solves the above-mentioned subject and relates to the artificial leather which reduced the use of a petroleum raw material by using the ultrafine fiber which consists of polylactic acid which is a plant-derived raw material. More specifically, the present invention provides an artificial leather that combines natural leather-like fullness and flexibility with sufficient practical strength.

That is, the present invention is a fiber entangled body obtained by laminating and integrating a nonwoven fabric composed of ultrafine fiber bundles and a woven or knitted fabric, and an artificial leather impregnated with a polymer elastic body therein, the following (1) to ( It is an artificial leather characterized by satisfying 3).
(1) The ultrafine fiber is made of polylactic acid (2) The strength of the single fiber constituting the woven or knitted fabric is 2.0 cN / dtex to 4.5 cN / dtex (3) A part of the polymer elastic body is extremely fine It is in close contact with the outer peripheral portion of the fiber bundle. And, it is a method for producing artificial leather, characterized by sequentially performing the following steps (1) to (5).
(1) A web or non-woven fabric composed of ultrafine fiber-generating fibers having polylactic acid as an island component and water-soluble polymer component as a sea component has a single fiber strength of 2.0 cN / dtex to 4.5 cN / dtex. A process of producing a fiber entangled body by laminating and integrating with a woven or knitted fabric (2) A process of dry-heat shrinking the fiber entangled body at an area shrinkage rate of 5% to 30% (3) A polymer elastic body inside the fiber entangled body Step of impregnating aqueous dispersion (4) Irradiation with infrared rays, moisture in fiber entangled body in a state where surface temperature of fiber entangled body is raised to a temperature higher by 10 ° C. or more than the gelation temperature of polymer elastic water dispersion (5) Step of extracting and removing water-soluble polymer components with hot water to form ultrafine fiber bundles

  The present invention can provide an artificial leather that is excellent in natural leather-like texture and flexibility and has sufficient practical strength even when a plant-derived plastic is used without using petroleum raw materials.

Hereinafter, the present invention will be described in detail.
As described above, the present invention is to obtain an artificial leather excellent in texture and physical properties using a petroleum substitute. For this reason, the ultrafine fiber which comprises the fiber entanglement body of this invention needs to be the polylactic acid of the plant origin plastics whose intensity | strength is comparable to polyester. The polylactic acid used in the present invention is mainly composed of a copolymer of optical isomers of L-lactic acid and D-lactic acid, and poly L-lactic acid is generally used. In the present invention, when poly L-lactic acid is used, the optical purity is preferably 90.0 to 99.5%. When the content of optical isomer D-lactic acid is increased, the crystallinity is lowered and the melting point is lowered, which may be inferior in heat resistance. In addition, when the D-body ratio decreases, biodegradation tends to be difficult. When used as a general practical fiber, heat resistance is often required, and from this viewpoint, the optical purity is more preferably 96.0 to 99.5%. Other examples include a copolymer of D-lactic acid and hydroxycarboxylic acid, and a copolymer of L-lactic acid and hydroxycarboxylic acid. The melting point of polylactic acid is preferably 80 ° C. or higher. Examples of the hydroxycarboxylic acid include glycolic acid, hydroxybutyric acid, hydroxyvaleric acid, hydroxypentanoic acid, hydroxycaproic acid, hydroxyheptanoic acid, and hydroxyoctanoic acid. In terms of spinnability and fiber strength to be obtained, the number average molecular weight of polylactic acid is preferably about 20,000 to 100,000, more preferably 40,000 to 100,000, still more preferably 60,000 to 100,000. 000. When the number average molecular weight is less than 20,000, sufficient strength as a fiber cannot be obtained. Conversely, when it exceeds 100,000, the fluidity of the polymer is poor and spinning becomes difficult.
It is preferable that 0.1 to 15% by mass of a hydrolysis inhibitor is added to the polylactic acid fiber with respect to the polylactic acid. That is, polylactic acid fibers are not sufficiently resistant to alkali hydrolysis. In particular, when the surface of the artificial leather of the present invention is brushed and dyed with a disperse dye to form a suede-like artificial leather, the artificial leather obtained by dyeing is The dye incorporated in the polymer elastic body represented by polyurethane is easy to peel off and the dyeing fastness is insufficient, so it is necessary to reduce and wash under alkaline conditions. A hydrolysis inhibitor is added in that it is easily hydrolyzed underneath and eliminates the fear of causing a decrease in strength.
And by setting it as 0.1 mass% or more, the alkaline hydrolysis-resistant inhibitory effect and thread | yarn physical property are excellent. Moreover, it is excellent in spinning stability by setting it as 15 mass% or less.
The hydrolysis inhibitor is preferably a general polyester end-capping agent, that is, one having a carbodiimide or glycidyl group that reacts with a terminal carboxylic acid, and among them, carbodiimide is more preferably used in terms of effectiveness. As a method for adding the hydrolysis inhibitor, a method of melt-kneading the hydrolysis inhibitor and the resin is preferably used.
The monofilament fineness constituting the nonwoven fabric of the artificial leather of the present invention is not particularly limited and can be arbitrarily selected depending on the use of the artificial leather, but the surface of the resulting artificial leather texture or suede-like artificial leather From the point of improving the appearance, 0.0001 to 0.5 dtex is preferable, 0.001 to 0.45 dtex is more preferable, and 0.002 to 0.3 in terms of color developability and gripping property of the polymer elastic body. Decitex is particularly preferred. As a method for obtaining these fibers, a method of converting an ultrafine fiber generating fiber into an ultrafine fiber bundle is preferably used in that an ultrafine fiber bundle can be obtained efficiently.

  As the ultrafine fiber-generating fiber, any of sea-island type fibers typified by sea-island type composite spun fibers, sea-island type mixed spun fibers, and multicomponent composite fibers such as petal-type and laminated-type fibers can be used. And it is preferable to use a sea island type fiber at the point which can perform ultrafine fiber formation stably. The above-mentioned polylactic acid is used as the island component of the sea-island fiber, but as the sea component, it is possible to generate ultrafine fibers without using a solvent, and the environment is considered, and polylactic acid is deteriorated by heat. Therefore, it is important that the extractable component is a water-soluble polymer component that can be spun as an extractable component that can reduce the heat application time during extraction. For example, as the water-soluble polymer component, a known polymer can be used as long as it is a polymer that can be extracted with an aqueous solution (hereinafter sometimes referred to as an aqueous solvent), but a polyvinyl alcohol copolymer that can be dissolved in an aqueous solvent can be used. It is preferable to use a compound (hereinafter sometimes abbreviated as PVA). PVA can be easily dissolved and removed with hot water, and since the decomposition reaction of the ultrafine fiber component and the elastic polymer component does not substantially occur during the extraction process, the thermoplastic resin and the high polymer elasticity used for the ultrafine fiber component It is preferably used from the point that there is no limitation on body components, and further in consideration of the environment.

The PVA may be a homopolymer or a modified polyvinyl alcohol introduced with a copolymer unit. However, from the viewpoints of melt spinnability, water solubility, fiber properties, and shrinkage characteristics during extraction processing, the copolymer unit may be Preferably, the introduced PVA is an α-olefin having 4 or less carbon atoms such as ethylene, propylene, 1-butene, isobutene, methyl vinyl ether, ethylene vinyl ether, n-propyl vinyl ether, i-propyl vinyl ether, n-butyl vinyl ether. More preferred are vinyl ethers such as Moreover, it is preferable that 1-20 mol% of units derived from α-olefins having 4 or less carbon atoms and / or vinyl ethers are present in PVA. Furthermore, when the α-olefin is ethylene, the fiber physical properties are improved, and therefore, it is more preferable to use PVA in which 4 to 15 mol% of ethylene units are particularly modified.
The saponification degree is preferably 90 to 99.99 mol%, more preferably 92 to 99.98 mol%, further preferably 94 to 99.96 mol%, and particularly preferably 95 to 99.95 mol%. When the saponification degree is less than 90 mol%, the thermal stability of PVA is poor and satisfactory composite melt spinning cannot be performed by thermal decomposition or gelation. On the other hand, PVA having a saponification degree larger than 99.99 mol% is difficult to produce stably.

  Moreover, as a mass ratio of the water-soluble polymer component and the polylactic acid component constituting the ultrafine fiber generating fiber, the range of 10/90 to 60/40 is the range of the water soluble polymer component in the cross section of the ultrafine fiber generating fiber. Since the dispersion stability of polylactic acid is good, the generated ultrafine fibers and ultrafine fiber bundles are uniform, the texture of the resulting artificial leather is excellent, and when it is made a suede-like artificial leather, a uniform raised feeling is obtained. This is preferable.

  The polylactic acid fiber constituting the ultrafine fiber bundle of the present invention may contain a pigment. Also, as a method for adding the pigment, in order to improve the dispersibility of the pigment in the polylactic acid constituting the ultrafine fiber, the polylactic acid constituting the ultrafine fiber and the pigment are kneaded using a compound facility such as an extruder. It is preferable to employ a method of adding a pigment by a master batch method in which pellets are formed. In addition, a stabilizer such as a copper compound, a colorant, an ultraviolet absorber, a light stabilizer, an antioxidant, an antistatic agent, a flame retardant, and a plasticizer are included in the ultrafine fiber component as long as the purpose and effect of the present invention are not impaired. Further, a lubricant and a crystallization rate retarder may be added during the polymerization reaction or in the subsequent steps. The kind of the fine particles is not particularly limited, and the polylactic acid may contain 0.1 to 5% by mass of fine particles having an average particle size of 10 μm or less, if necessary, at the time of polymerization or after polymerization. For example, silica gel (colloidal silica) fine particles, dry method silica fine particles, dry method silica fine particles containing aluminum oxide, dry method silica fine particles having an alkyl group on the particle surface and blocking silanol groups on the particle surface, alumina sol (colloidal) Preferable examples include alumina) fine particles, alumina fine particles, titanium oxide fine particles, calcium carbonate sol (colloidal calcium carbonate) fine particles, inert fine particles such as barium sulfate, and internal precipitation fine particles in which a phosphorus compound and a metal compound are precipitated. These may be used alone or in combination of two or more, and the spinnability and stretchability may be improved.

The spinning method of the ultrafine fiber generating fiber is not particularly limited as long as it is a known method, but when a water-soluble polymer component is used as the sea component of the sea-island fiber, for example, a spinning temperature of 160 to 260 ° C, Spinning at a spinning speed of 100 to 1000 m / min is preferable from the viewpoint of spinning stability. Next, the film is usually stretched after spinning, but it may be drawn once after being discharged from the spinning nozzle and then drawn, or it may be drawn before being drawn, and either method may be used. The stretching method is usually hot stretching, but may be performed using any of hot air, a hot plate, a hot roller, a water bath, and the like. However, when one component of the ultrafine fiber-generating fiber is a water-soluble polymer component, it is preferable to draw with hot air that is less affected by moisture on the water-soluble polymer component.
The stretching conditions are preferably 0.55 times or more and more preferably 0.7 times or more of the cutting stretch ratio in that an artificial leather having sufficient strength can be obtained.

The method for producing a fiber entangled body according to the present invention is, for example, a method of forming a short fiber web by cross-wrapping or random webber, etc. A known method such as a method of forming from a long fiber web represented by a spunbond web or the like can be used. The basis weight of the web is preferably 100 to 1000 g / m ^{2 from} the viewpoint of process passability.
Moreover, in this invention, as above-mentioned, the ultrafine fiber which comprises a nonwoven fabric uses the polylactic acid of the plant origin plastics whose intensity | strength is comparable to polyester. However, physical properties are likely to deteriorate due to dyeing, reduction / washing under alkaline conditions, or subsequent hydrolysis.
Therefore, in the present invention, a specific woven or knitted fabric is inserted so as to reinforce the physical properties and yet not impair the natural leather-like sense of fullness and flexibility. This makes it possible to maintain practical strength even in processing under high temperature and high humidity conditions.
The fibers constituting the woven or knitted fabric to be used are, for example, artificial leather, and those that can obtain practical strength in the intended use are preferably used. Fibers made of known polymers can be selected, and dyeability From the viewpoint of physical properties and texture, polyester polymers are preferably used. However, in the present invention, it is important that the strength of the single fiber constituting the woven or knitted fabric is 2.0 cN / dtex to 4.5 cN / dtex in order to reinforce the polylactic acid fiber and not impair the texture as the artificial leather. is there. If it is less than 2.0 cN / dtex, the reinforcing effect is not sufficient, and if it exceeds 4.5 cN / dtex, the fiber tends to be hard and the texture of the artificial leather is impaired. The range of the strength can be set to a desired range by appropriately adjusting, for example, the degree of polymerization of the raw material polyester polymer, the spinning speed, and the stretching speed.
Further, when a woven or knitted fabric is constituted by a yarn in which a plurality of fibers are bundled, the number of twists of the yarn is not particularly limited. However, since the woven or knitted fabric forms an integral structure with the ultrafine generation type fiber, the number of twists is 10 to 650 T. / M is preferable, and 15 to 500 T / m is more preferable. If it is less than 10 T / m, the single yarn of the knitted or knitted fabric tends to collapse when entangled with the web, and the damaged yarn is greatly exposed to the surface, which may deteriorate the appearance. On the other hand, if the twist number exceeds 650 T / m, it is difficult to obtain an integral structure firmly intertwined with the web, and the natural leather-like solidity and flexibility are likely to be impaired.
Of woven or knitted fabric basis weight can be set as appropriate depending on the purpose, is preferably ^{20~200g / m 2, 30~150g / m} 2 is more preferable. If the basis weight is less than 20 g / m ² , the shape of the woven or knitted fabric becomes very loose, and the fabric is not stable such as misalignment. If the basis weight exceeds 200 g / m ² , the interval between the yarns constituting the woven or knitted fabric is too small. It becomes dense, the penetration of the fibers that make up the web is inadequate, the high entanglement between the web and the woven or knitted fabric does not progress, it is difficult to make a structure that is separated and integrated, Flexibility is difficult to obtain.
As the types of woven and knitted fabrics, weft knitting represented by warp knitting and tricot knitting, lace knitting and various knittings based on these knitting methods, or plain weaving, twill weaving, satin weaving and weaving these The various woven fabrics are not particularly limited. Which one to select, such as tissue or density, may be determined appropriately according to the purpose.

In the obtained web, it is necessary to laminate the woven or knitted fabric described above on the surface layer, lower layer or intermediate layer of the web and entangle the fibers by needle punching.
However, it is preferable that the web is pre-entangled to make a nonwoven fabric in terms of excellent process passability. As the conditions for temporary entanglement, known temporary entanglement conditions when a nonwoven fabric and a woven fabric are laminated and integrated can be used. Next, in the present invention, the nonwoven fabric and the woven or knitted fabric are laminated, but the lamination method is performed by a known method and is not particularly limited. The ratio of lamination varies depending on the use of the artificial leather to be obtained. When artificial leather is used, the mass ratio of the nonwoven fabric to the woven / knitted fabric is 95/5 to 70/30. This is preferable in that it has both flexibility and mechanical properties.
As the needle punch conditions, the total needle punch number is preferably 400 to 5000 punches / cm ² including the condition that the barb of the needle needle penetrates from the nonwoven fabric to the surface of the woven or knitted fabric, more preferably 1000 to The condition is 2000 punch / cm ² .
Nonwoven and woven or knitted fabric lamination, density of the obtained fiber-entangled body integrally entangled is preferably ^{0.20~0.80g / cm 3, 0.25~0.70g / cm} 3 is more preferable. If it is less than 0.20 g / cm ³ , the nap feeling and mechanical properties of the fiber when it is made into a suede-like artificial leather are insufficient, and if it exceeds 0.80 g / cm ³ , the texture becomes hard. And the thickness of a fiber entangled body will not be specifically limited if the said fabric weight range and the density range are satisfy | filled.

Next, in order to increase the fluff density of the fiber so as to obtain a good appearance and texture, the fiber entangled body is subjected to dry heat shrinkage from the viewpoint of surface abrasion resistance when it is made into a suede-like artificial leather.
By subjecting the fiber entangled body to a heat treatment and a heat shrinking treatment, the fiber density in the fiber entangled body can be increased, and a dense napped appearance and a good texture can be obtained. Further, after heat shrinkage, hot pressing may be performed as necessary to improve the smoothness of the artificial leather surface. Here, in the present invention, when a water-soluble polymer component is used as an extraction component of an ultrafine fiber-generating fiber that generates polylactic acid ultrafine fibers, when the hot water shrinkage treatment is performed, all the extracted components are eluted, and thereafter Since the polymer elastic body to be applied is fixed to all the polylactic acid ultrafine fibers, there is a possibility that the texture may be impaired. In addition, it is preferable to perform at a temperature lower than the melting point of the polylactic acid used in the present invention, in particular, to perform a dry heat shrinkage treatment under a condition of 20 ° C. or less because deterioration due to heat hardly occurs. In particular, the fiber entangled body is preferably subjected to dry heat shrinkage under such a condition that the area shrinkage rate is 5% or more and 30% or less. By setting it to 5% or more, it is possible to improve the process passability and to obtain a texture with the physical properties and fulfillment of the artificial leather obtained, and by setting it to 30% or less, it is a flexible and fulfilling texture. It can be.
The basis weight of the obtained fiber entangled body can be arbitrarily selected depending on the use of the obtained artificial leather and is not particularly limited, but is preferably 300 to 1500 g / m ² . The apparent density is preferably 0.25 to 0.80 g / cm ³ . 0.26 to 0.70 g / cm ³ is preferable. By setting it to 0.25 g / cm ³ or more, it is easy to obtain mechanical properties and a texture with a sense of fulfillment of artificial leather, and further, it is possible to obtain a dense raised feeling of fibers when made into a suede-like artificial leather. A texture can be made flexible by setting it as 0.80 g / cm < ³ > or less. And the thickness of a fiber entangled body will not be specifically limited if the said fabric weight range and the density range are satisfy | filled.

In the present invention, a known resin used for artificial leather can be used as the polymer elastic body contained in the fiber entangled body. The application method is not particularly limited, but when a water-soluble polymer component typified by polyvinyl alcohol is used as one component of the ultrafine fiber-generating fiber, it is preferably impregnated as an aqueous dispersion of a polymer elastic body. As a result, when the polymer elastic body is impregnated into the fiber entangled body and then gelled, solidified and dried, the water-soluble polymer component constituting the outer periphery of the ultrafine fiber-generating fiber is dispersed in the polymer elastic body aqueous dispersion. By dissolving in a specific range with water, the polymer elastic body penetrates from the outer periphery of the ultrafine fiber bundle into the fiber bundle, and a part of the polymer elastic body solidified after drying can be adhered to the outer periphery of the ultrafine fiber bundle. In addition, it is possible to make it stick within a specific range inside the ultrafine fiber bundle. And when it is finally finished as artificial leather or suede-like artificial leather, the texture is soft, the gripping property of the ultrafine fibers by the polymer elastic body is good, and the quality degradation due to fluffing etc. can be greatly suppressed Obtainable. Furthermore, since polylactic acid is used as the ultrafine fiber, the ultrafine fiber is easily softened, and the polymer elastic body and the polylactic acid firmly adhered to the outer peripheral portion of the ultrafine fiber bundle are firmly fixed, so that subsequent drying treatment and dyeing treatment are performed. The polymer elastic body does not easily fall off from polylactic acid even after passing through, and as a result, the non-woven fabric layer composed of the polylactic acid fiber and the polymer elastic body inside the non-woven fabric constituting the resulting artificial leather forms a very dense structure To do. On the other hand, in the woven or knitted fabric, the softening temperature of the fibers constituting the woven or knitted fabric is preferably higher than the softening temperature of polylactic acid, more preferably 30 ° C or higher, and particularly preferably 50 ° C or higher. Although an upper limit is not specifically limited, it shall be 250 degrees C or less. By making the softening temperature higher than that of polylactic acid fiber, the polymer elastic body fixed to the woven or knitted fabric is particularly easy to fall off by performing drying treatment or dyeing treatment after impregnation, and the polymer elastic body constitutes the woven or knitted fabric. Exist with voids. As a result, although the fine fibers are dense and the fluff density is improved, it is possible to obtain an artificial leather having a soft texture and excellent quality.
In addition, the voids can be made larger by coating the yarn constituting the knitted or knitted fabric with PVA or the like to give the polymer elastic body and then removing the PVA coated on the yarn.
And by having this void, the surface side becomes a dense structure, the back side becomes a rough structure, density spots in the thickness direction of artificial leather are formed, more natural leather-like texture and surface properties or suede-like artificial leather This makes it possible to achieve both excellent lighting effects.
The void described here refers to a space existing between the outer periphery of the yarn constituting the woven or knitted fabric and the polymer elastic body, and the polymer elastic body penetrates into the yarn constituting the woven or knitted fabric. The rate of penetration is less than 1%. And the state which has not penetrated partially is preferred. A state in which it is not substantially adhered to the yarn is more preferable.
These states can be confirmed by observing the presence of voids in an electron micrograph.
Permeability is the outer periphery of a yarn in which a part of the polymer elastic body constitutes a woven or knitted fabric (in the cross section of the fiber bundle constituting the yarn, the part farthest from the inside of the yarn constituting the outermost circumference of the yarn, respectively) Area ratio ((area of polymer elastic body permeating into the outer periphery) / (area inside the outer perimeter)) × 100% ).

  When the polymer entangled body is impregnated with the polymer elastic aqueous dispersion, a known technique such as a dip nip method can be used, but the sea entangled fiber is composed of a water-soluble polymer component and polylactic acid. In the case of impregnating a polymer elastic body aqueous dispersion inside a fiber entangled body using a nonwoven fabric composed of a water-soluble polymer component in the sea-island fiber due to pressure by the nip treatment, the polymer elasticity The body water dispersion is contaminated. For this reason, in the combination, not using the dip nip method, but utilizing the permeability of the polymer elastic water dispersion to the water-soluble polymer component, without greatly pressing and supplying the polymer elastic water dispersion, It is preferable to use a resin impregnation method in which a predetermined amount of resin can be impregnated only by controlling the supply amount and concentration of the polymer elastomer aqueous dispersion to the fiber entanglement, for example, a lip coater.

  Further, the water dispersion of the polymer elastic body to be impregnated indicates that the polymer elastic body is substantially discontinuously present inside the fiber entangled body after solidification, which indicates that the polymer elastic body can hold the fiber and the flexible wind. It is preferable at the point which combines, and it is preferable to provide so that it may become mass ratio of polymeric elastic body: fiber entanglement body = 5: 95-60: 40. In the case of artificial leather, the polymer elastic body obtains an effect as a binder for binding fibers. When the ratio of the polymer elastic body is 5 or more, the binder effect is sufficient, and when it is 60 or less, the tear strength is high. Excellent in physical properties such as tensile strength and tend to be flexible.

  In the present invention, after the fiber entangled body is impregnated with an aqueous dispersion of a polymer elastic body, the gripping property of the polylactic acid ultrafine fiber constituting the nonwoven fabric made of the polymer elastic body is suppressed while suppressing the migration and maintaining the texture of the product. In order to keep the water, the polymer elastic water dispersion is rapidly gelled while dissolving a part of the water-soluble polymer component of the sea component of the sea-island fiber that forms the nonwoven fabric before the water completely evaporates. . Since the appearance quality is further improved and the texture of the product is not impaired due to excessive adhesion with the ultrafine fiber bundle, a part of the polymer elastic body is part of the outer periphery of the ultrafine fiber bundle (in the bundle cross section of the ultrafine fiber bundle). The area ratio (the polymer penetrating into the inside of the outer peripheral portion) from the inside of the ultra fine fiber bundle constituting the outermost circumference of the fiber bundle to the inside of the bundle from the area farthest from the inside of the ultra fine fiber bundle. It is preferable to permeate in the range of 1 to 30% by (area of elastic body) / (area inside the outer peripheral portion) × 100%). In addition, when finished as a suede-like artificial leather, the ultrafine fiber bundle is firmly gripped with a polymer elastic body so that the ultrafine fibers on the surface do not fall out, and the fine fibers are reasonably fine in terms of appearance quality, surface properties and texture. Is preferably 1.5 to 25%, particularly preferably 2 to 20%, from the viewpoint that it is necessary to disperse. Therefore, in the present invention, the fiber entanglement obtained by applying the polymer elastic water dispersion to the inside of the nonwoven fabric and the woven or knitted fabric composed of the sea-island fiber having the water-soluble polymer component as the sea component and polylactic acid as the island component is rapidly applied. In order to dissolve the water-soluble polymer component at the same time, an infrared irradiation treatment is performed. The infrared rays used in the present invention are advantageous for raising the temperature of the surface and the inside of the fiber entangled body, and are very advantageous for raising the temperature of the polymer elastic aqueous dispersion because it contains an infrared absorption wavelength of 2.6 μm of water. It is preferable to use infrared rays having a maximum energy wavelength of 2 to 6 μm in view of the above and a good balance between absorption and transmission of infrared rays of the fiber entangled body to which the polymer elastic water dispersion is applied. Then, the moisture content of the fiber entangled body is 50% or less in a state where the surface temperature of the fiber entangled body, particularly the nonwoven fabric side is raised to a temperature higher by 10 ° C. or more than the gelling temperature of the polymer elastic water dispersion. After that, the remaining water is dried and removed to solidify the elastic polymer.

As the temperature rise time of the surface temperature of the fiber entangled body, particularly the nonwoven fabric, the surface temperature of the fiber entangled body may be raised to a temperature higher by 10 ° C. or more than the gelation temperature of the polymer elastic body aqueous dispersion within 1 minute. preferable. If the surface temperature on the nonwoven fabric side during infrared irradiation is equal to or higher than the gelling temperature of the polymer elastic water dispersion + 10 ° C., the temperature inside the fiber entangled body reaches or exceeds the gelling temperature of the polymer elastic water dispersion. It is easy to promote thermal gelation of the polymer elastic body. And, it is possible to suppress the time for raising the surface temperature of the nonwoven fabric side to the gelling temperature of the polymer elastic water dispersion + 10 ° C. or more within 1 minute before the polymer elastic water dispersion causes migration. This is preferable because it is easily heat-sensitive gelled. Further, in this treatment, a part of the water-soluble polymer component is dissolved by the water of the polymer elastic body aqueous dispersion during the temperature rise, and as a result, the ultrafine fiber component is appropriately exposed and the polymer elastic body can be directly contacted. In particular, it is preferable because a structure in which a part of the polymer elastic body penetrates from the outer peripheral portion of the ultrafine fiber bundle to the inside of the bundle in an area ratio of 1 to 30% over the entire nonwoven fabric layer is preferable.
And it is necessary to make the moisture content which this fiber entanglement body contains in the state heated up by infrared irradiation to 50% or less. By setting the amount to 50% or less, the water-soluble polymer component of the sea-island fiber constituting the nonwoven fabric of the fiber entangled body is appropriately dissolved at the time of subsequent heating and drying, so that the polymer elastic body is directly inside the ultrafine fiber bundle. The ratio of penetrating in an area ratio of 1 to 30% is increased, and the texture of the artificial leather becomes flexible by making migration difficult during subsequent heating and drying. The lower limit of the moisture content is not particularly limited, but is preferably 10% or more in terms of drying efficiency.
The moisture content here can be determined by the following calculation method.
[Moisture percentage]
H = (I−J) / J × 100
H: Moisture content (%)
I: Weight of fiber entangled body after impregnating polymer elastic water dispersion and infrared irradiation (g / m ² )
J: Weight of fiber entangled body impregnated with polymer elastic water dispersion and coagulated and dried (g / m ² )
Moreover, when performing infrared irradiation, in order to heat both surfaces of a fiber entangled body uniformly, it is preferable to irradiate from the both surfaces under the same conditions, and in order to make the water volatile state volatile from both surfaces uniform, it is a vertical type. It is more preferable.

After the infrared irradiation treatment, a heat drying treatment is performed in order to evaporate 50% or less of the water remaining in the fiber entangled body and to firmly adhere the impregnated and solidified polymer elastic body to the nonwoven fabric fiber. . When finished as a suede-like artificial leather using the resin entangled fiber entangled resin obtained without heat drying treatment, the polymer is extracted with hot fiber during extraction and removal of water-soluble polymer components and hot water during dyeing treatment. The elastic body swells and falls off, and the fibers in the surface layer are inadequately held by the polymer elastic body, resulting in poor appearance quality.
The heat drying treatment method may be a known method such as hot air drying or wet heat drying, and the heat drying treatment temperature can be arbitrarily set according to the solidification characteristics of the polymer elastic body.

Next, after impregnating and coagulating an aqueous dispersion of a polymer elastic body into a fiber entanglement composed of an ultrafine fiber generating fiber composed of a water-soluble polymer component and polylactic acid, a non-solvent for the ultrafine fiber and the polymer elastic body is obtained. In addition, the water-soluble polymer component is extracted and removed with a treatment solution, ie, an aqueous solution, which is a solvent of the extraction and removal component, and the ultrafine fiber generation type fibers are bundled into ultrafine fibers.
In particular, when extracting and removing water-soluble polymer components, from the viewpoint of environmental problems, a method of removing ultrafine fiber-generating fibers by removing the extracted and removed components with hot water or the like is preferable. When extracting with hot water especially, the temperature of 60-100 degreeC is preferable as hot water temperature, and 80-95 degreeC is more preferable. It is possible to shorten the extraction time by removing the water-soluble polymer component at 60 ° C. or higher. Therefore, the higher the hot water temperature, the better. Moreover, by setting it as 100 degrees C or less, the binding of the provided polymer elastic body and an ultrafine fiber is hard to loosen, and it becomes easy to maintain the fiber grip property which a polymer elastic body has.
The equipment for bundling ultrafine fibers is not particularly limited, but a liquid flow treatment device is preferable because a polymer elastic body adhering to the woven or knitted fabric described above is easily dropped, and a circular or winch device is used. It is preferable to do.

In the present invention, before or after the dyeing step, the surface of the artificial leather on the non-woven fabric side is subjected to a known raising process such as buffing to form an ultrafine fiber raised surface mainly composed of ultrafine fibers to obtain a suede-like artificial leather. When adjusting the thickness, buffing treatment may be performed before or after the ultrafine fiber generating fiber is made ultrafine, but when the surface is raised, the polymer elastic water dispersion is applied to the surface of the artificial leather and dried. It is preferable that after raising a part of the ultrafine fibers constituting the fiber bundle, the raising treatment is performed in order to stably obtain the stability of the raising treatment and the uniform fluff length. Further, if necessary, surface finishing treatment such as softening treatment such as stagnation and reverse seal brushing can be performed. The suede-like artificial leather obtained in the present invention has a good texture and a good quality appearance.
Moreover, after giving a polymeric elastic body to the surface of the obtained artificial leather, it can be set as a silver surface artificial leather by a well-known surface finishing method. And it is set as desired thickness by pressurization heating processing, division processing, etc. as needed.

The obtained artificial leather is dyed with a high-temperature and high-pressure dyeing machine using a disperse dye and, if necessary, a dispersant, a pH adjuster and a sequestering agent. Dyeing is possible even if a cationic dye or other reactive dye is used as the dye. The bath ratio during dyeing is preferably 10 to 40 times the mass of the artificial leather. The dye concentration is preferably in the range of 1 to 35% owf in terms of color developability. By setting it as the above, the artificial leather which has color development and practical physical properties, such as dyeing fastness and washing fastness, can be obtained. The dyeing temperature is 115 to 150 ° C, preferably 120 to 140 ° C. By setting the temperature to 115 ° C. or higher, the disperse dye can be easily diffused into the polylactic acid fiber. By setting the temperature to 150 ° C. or lower, hydrolysis of a polymer elastic body typified by polyurethane constituting the artificial leather hardly occurs, and the resulting suede artificial leather has reduced strength, fluff loss, pilling, etc. It becomes difficult.
Subsequently, the excess dye in the artificial leather is reductively decomposed and washed away at a temperature of 50 to 80 ° C. in the presence of an alkaline agent using 2 to 10 g / l of a reducing agent and a reducing agent equivalent to the reducing agent. . When the temperature is lower than 50 ° C., washing of excess dye in the polymer elastic body tends to be insufficient. When the temperature exceeds 80 ° C., the dye in the fiber is reduced and washed. As the reducing agent, those generally used for reducing and washing polyester such as thiourea dioxide and hydrosulfite can be preferably used. When the amount of the reducing agent is less than 2 g / l, it is difficult to sufficiently decompose and wash the dye in the polymer elastic body, and color spots are likely to occur and color reproducibility tends to be reduced. On the other hand, if it exceeds 10 g / l, the decomposition and cleaning effects of the dye are not changed, which is disadvantageous in terms of cost.
Next, oxidation and neutralization are performed by a known method to complete the dyeing.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited at all by these Examples.

Example 1
Polylactic acid (Cargill's melting point 170 ° C) with 2% by mass of Stavaxol P (made by Rhein Chemie) having carbodiimide as a hydrolysis inhibitor added to the polylactic acid solid content is an island component, containing 10 mol% of ethylene units 64 islands-type fibers having a saponification degree of 98.4 mol% and a melting point of 210 ° C. as a sea component and a mass ratio of sea / island = 30/70 After composite spinning at a spinning temperature of 240 ° C. and a spinning speed of 800 m / min, a fiber having a single fineness of 4.6 dtex and an ultrathinned island fiber of 0.043 dex is obtained by drawing at a cutting draw ratio of 0.75 times. It was. This fiber was crimped, cut to a fiber length of 51 mm, and carded to create a short fiber web.
Next, a yarn made of polyester (softening temperature 240 ° C., single fiber strength 3.5 cN / dtex) subjected to false twisting of 56 dtex / 24f was subjected to additional twisting of 600 T / m, and then a weave density of 127 Weaving was performed at × 95 pieces / inch to obtain a plain fabric with a basis weight of 55 g / m ² . After laminating the web and plain woven fabric, needle processing was performed under the condition of 1500 punch / cm ² , and the area was shrunk by about 15% by dry heat shrinkage at 150 ° C., the basis weight was 380 g / m ² , and the apparent density was 0.288 g / cm ^3. A fiber entangled body having a thickness of 1.45 mm was obtained.

Next, a polycarbonate / ether polyurethane aqueous dispersion emulsion (Evaphanol APC-28, manufactured by Nikka Chemical Co., Ltd.), a thickener (Neo sticker manufactured by Nikka Chemical Co., Ltd.), and a light resistant agent (NK assist HAL, manufactured by Nikka Chemical Co., Ltd.) Was added to the emulsion and diluted with water to obtain an aqueous dispersion of a polymer elastic body having a concentration of 10% by mass and a density of 1.02 g / cm ³ . The gelation temperature of this polymer elastic water dispersion was 60 ° C.

  Next, a lip coater equipment (Hipano Techseed's lip direct system) is used as the impregnation equipment, and an aqueous dispersion of polymer elastic body (fiber entangled fiber + woven / knitted fiber) / polymer elastic body = 80 / Impregnation was performed so that the mass ratio was 20. After impregnation with the polymer elastic water dispersion, infrared rays having a maximum energy wavelength of 2.6 μm were irradiated at 97 V for 60 seconds, and the fiber entangled surface temperature was raised to 100 ° C. within 1 minute. The moisture content after 60 seconds of infrared irradiation was about 40%. Then, it was heated and dried with a hot air dryer at 155 ° C. for 5 minutes and 20 seconds to completely evaporate the moisture and cure the polymer elastic body to fix it to the fiber entangled body. Thereafter, the polyvinyl alcohol copolymer was extracted with hot water at 90 ° C., and at the same time, the polyurethane adhering to the fabric was removed to obtain an artificial leather. The obtained artificial leather had a good appearance without wrinkles and elongation, and had a leather-like uniform texture and excellent physical properties.

  Next, after smoothing the surface, Yellow 3RF 0.24owf%, Red GF 0.34owf%, Blue GF 0.70owf%, antifade MC-500 (Sumikaron UL dye (manufactured by Sumitomo Chemical Co., Ltd.)) as a disperse dye. High pressure dyeing was performed at 105 ° C. for 30 minutes using 2 owf%, Disper TL (manufactured by Meisei Chemical Co., Ltd.) 1 g / L. Thereafter, reduction treatment was performed at 60 ° C. for 15 minutes using soda ash, and monogen washing was performed at 60 ° C. for 20 minutes. The resulting dyed product was subjected to buffing treatment using 400-th paper and the surface fibers were trimmed to obtain a suede-like artificial leather. In the obtained artificial leather, a part of the polymer elastic body is in close contact with the outer peripheral part of the polylactic acid ultrafine fiber bundle, and a part of the polymer elastic body is 3% in area ratio from the outer peripheral part of the ultrafine fiber bundle to the inside of the bundle. The nonwoven fabric layer made of polylactic acid ultrafine fibers had a very dense structure, and the periphery of the yarn constituting the woven or knitted fabric had voids. The artificial leather had excellent mechanical properties with a vertical strength of 35.9 kg / 2.5 cm, a horizontal size of 28.5 kg / 2.5 cm, and a tear strength of vertical length of 1.9 kg and a horizontal size of 2.0 kg. The strength after performing a jungle test of this artificial leather at 70 ° C.-95% RH is 34.5 kg / 2.5 cm in length, 28.0 kg / 2.5 cm in width, 1.5 kg in tear strength, 2.1 kg in width. Thus, the physical properties were excellent and the mechanical properties that can withstand practical use were not greatly deteriorated. In addition, there were no creases, wrinkles, etc., the natural leather-like sense of fullness and flexibility were very good, the fluff length was uniform, and the appearance was good.

Example 2 (Weaving and knitting strength change)
The same treatment as in Example 1 was performed except that the strength of the single fiber constituting the woven or knitted fabric of Example 1 was 4.0 cN / dtex. As a result, the physical properties of the obtained artificial leather were not greatly deteriorated, and the mechanical properties withstand practical use were excellent. In addition, there were no creases, wrinkles, etc., the natural leather-like sense of fullness and flexibility were very good, the fluff length was uniform, and the appearance was good.

Comparative Example 1 (no woven or knitted fabric inserted)
The same treatment as in Example 1 was performed except that the woven or knitted fabric of Example 1 was not inserted. As a result, the strength of the obtained artificial leather was 18.7 kg / 2.5 cm in length and 14.1 kg / 2.5 cm in width, and was inferior in mechanical properties. Further, the physical strength of this artificial leather after being treated at 70 ° C. and 95% RH jungle test was 6.4 kg / 2.5 cm in length and 4.8 kg / 2.5 cm in width.

Comparative Example 2 (Change in physical properties of woven and knitted fabrics)
The same treatment as in Example 1 was performed except that a fiber having a strength of 1.5 cN / dtex was used as the strength of the fiber constituting the woven or knitted fabric of Example 1. As a result, the obtained artificial leather is free of creases, wrinkles, etc., and the natural leather-like feel and flexibility are very good, and the fluff length is uniform and has a good appearance, but the physical properties are large. The mechanical properties were inferior and were inferior in practical use.

Claims (8)

A fiber entangled body formed by laminating and integrating a nonwoven fabric and a woven or knitted fabric composed of ultrafine fiber bundles, and an artificial leather impregnated with a polymer elastic body, and satisfies the following (1) to (3) Artificial leather characterized by that.
(1) The ultrafine fiber is made of polylactic acid (2) The strength of the single fiber constituting the woven or knitted fabric is 2.0 cN / dtex to 4.5 cN / dtex (3) A part of the polymer elastic body is extremely fine Close contact with the outer periphery of the fiber bundle   The artificial leather according to claim 1, wherein the polymer elastic body is present with a thread and a gap constituting the woven or knitted fabric.   The artificial leather according to claim 1 or 2, wherein the polylactic acid contains a hydrolysis inhibitor in an amount of 0.1 to 15 mass% with respect to the polylactic acid.   The artificial leather according to any one of claims 1 to 3, wherein a softening temperature of a fiber constituting the knitted or knitted fabric is 30 ° C or more higher than a softening temperature of polylactic acid.   The artificial leather according to any one of claims 1 to 4, wherein a part of the polymer elastic body is permeated in an area ratio of 1 to 30% from the outer periphery of the ultrafine fiber bundle to the inside of the bundle. .   A suede-like artificial leather obtained by raising a nonwoven fabric side surface of the artificial leather according to any one of claims 1 to 5, further dyeing with a disperse dye, and reducing and washing under alkaline conditions. The manufacturing method of artificial leather characterized by sequentially performing the following steps (1) to (5).
(1) A web or non-woven fabric composed of ultrafine fiber-generating fibers having polylactic acid as an island component and water-soluble polymer component as a sea component has a single fiber strength of 2.0 cN / dtex to 4.5 cN / dtex. A process of producing a fiber entangled body by laminating and integrating with a woven or knitted fabric (2) A process of dry-heat shrinking the fiber entangled body at an area shrinkage rate of 5% to 30% (3) A polymer elastic body inside the fiber entangled body Step of impregnating aqueous dispersion (4) Irradiation with infrared rays, moisture in fiber entangled body in a state where surface temperature of fiber entangled body is raised to a temperature higher by 10 ° C. or more than the gelation temperature of polymer elastic water dispersion (5) Step of extracting and removing water-soluble polymer components with hot water to form ultrafine fiber bundles A method for producing a suede-like artificial leather in which the surface of the artificial leather obtained in claim 7 is subjected to brushing treatment, dyed with a disperse dye, and then subjected to reduction cleaning under alkaline conditions.