Synthetic leather

Abstract

A synthetic leather 1, 10 according to an embodiment comprises a fibrous base material 2 and a resin layer 3 provided on the fibrous base material 2, and has a plurality of openings 7 penetrating the fibrous base material 2 from a surface of the resin layer 3. The plurality of openings 7 each have an opening peripheral edge part 71 having a shape inclined so that the surface of the resin layer 3 goes down toward the center of the opening 7. The fibrous base material 2 includes: a warp knitted fabric 4 including a ground structure 41 and nap 42; and a mixed layer 6 provided between the ground structure 41 and the resin layer 3 and in which the nap 42 and a porous polyurethane resin 5 are mixed. The nap 42 does not protrude from the surface of the mixed layer 6.

Description

[Technical Field]

[0001] This invention relates to synthetic leather. [Background technology]

[0002] Synthetic leather has a resin layer covering its surface. Therefore, when used as an interior material for vehicles, especially for seats, it can cause problems such as stuffiness and stickiness due to perspiration during prolonged sitting. To address this, there are attempts to solve the problem of stuffiness and stickiness by creating multiple openings in the leather through perforation processing, thereby improving the breathability of the leather.

[0003] For example, Patent Document 1 describes a vehicle surface material comprising synthetic leather with openings, wherein a woven fabric is attached to the back surface of synthetic leather comprising a fibrous base material and a polyurethane resin layer via an adhesive layer. The synthetic leather is provided with a plurality of openings that penetrate the fibrous base material from the surface of the polyurethane resin layer, and the opening ratio is set to 1 to 15%.

[0004] Patent Document 2 describes a sheet-like material having an opening, comprising a fibrous base material and an inner layer and an outermost layer made of polyurethane resin laminated on the fibrous base material. The opening provided on the surface of the sheet-like material is configured to include an opening periphery portion in which the outermost layer is inclined toward the center of the opening. It is stated that this provides the sheet-like material with good abrasion resistance and surface feel. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2017-165209 [Patent Document 2] Japanese Patent Publication No. 2019-112737 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] In synthetic leather having openings, it is advantageous to create openings by penetrating a fibrous base material from the surface of the resin layer to further improve breathability. However, in this case, fuzz is easily generated from the fibrous base material due to abrasion, and the fuzz is exposed on the surface of the synthetic leather through the openings, which spoils the appearance. According to Patent Document 2, abrasion resistance can be improved by the above-mentioned inclined shape of the periphery of the opening, but when creating openings by penetrating a fibrous base material, it is difficult to improve abrasion resistance while suppressing the exposure of fuzz.

[0007] This invention has been made in view of the current situation, and its purpose is to provide synthetic leather with good breathability, abrasion resistance, and appearance. [Means for solving the problem]

[0008] The present invention includes embodiments shown below. [1] A synthetic leather comprising a fibrous base material and a resin layer provided on the fibrous base material, wherein a plurality of openings are provided from the surface of the resin layer through the fibrous base material, and the plurality of openings have an opening periphery that is inclined such that the surface of the resin layer falls toward the center of the opening, and the fibrous base material comprises a warp-knitted fabric including a base fabric and pile, and a mixed layer provided between the base fabric and the resin layer in which the pile and porous polyurethane resin are mixed, wherein the pile does not protrude from the surface of the mixed layer on the resin layer side. [2] The synthetic leather according to [1], wherein the layer of porous polyurethane resin without the pile is substantially absent on the resin layer side of the mixed layer, where substantially absent means that the layer without the pile is absent or, if present, the thickness of the layer without the pile is less than 50 μm. [3] The synthetic leather according to [1] or [2], wherein the thickness of the resin layer is 90 to 200 μm. [4] The synthetic leather according to any one of [1] to [3], wherein the opening ratio on the surface of the synthetic leather is 5 to 13%. [5] The synthetic leather according to any one of [1] to [4], wherein in the fibrous base material, the porous polyurethane resin is impregnated in at least a part of the ground tissue. [6] The synthetic leather according to any one of [1] to [5], wherein the resin layer includes an adhesive layer, a surface layer, and a surface treatment layer in this order on the fibrous base material. [7] The synthetic leather according to any one of [1] to [6], wherein the thickness of the mixed layer is 0.4 to 1.2 mm.

Advantages of the Invention

[0009] According to an embodiment of the present invention, it is possible to provide a synthetic leather having good air permeability, abrasion resistance, and appearance.

Brief Description of the Drawings

[0010] [Figure 1] It is a schematic cross-sectional view of a synthetic leather according to an embodiment. [Figure 2] It is a schematic cross-sectional view of a synthetic leather according to another embodiment. [Figure 3] It is a schematic cross-sectional view of a fibrous base material for explaining the thickness of the mixed layer and the thickness of the layer where no pile exists.

Mode for Carrying Out the Invention

[0011] The synthetic leather according to this embodiment includes a fibrous base material and a resin layer provided on the fibrous base material. The synthetic leather is provided with a plurality of openings penetrating the fibrous base material from the surface of the resin layer. These plurality of openings have an opening peripheral edge portion with a shape inclined such that the surface of the resin layer drops toward the center of the opening. The fibrous base material includes a warp knitted fabric including a ground tissue and pile, and a mixed layer provided between the ground tissue and the resin layer and in which the pile and the porous polyurethane resin are mixed. Further, the pile does not protrude from the surface on the resin layer side of the mixed layer.

[0012] According to this embodiment, by providing a plurality of openings penetrating the synthetic leather in this way, the air permeability is excellent. Further, since a warp knitted fabric having pile is used and a mixed layer in which pile and a porous polyurethane resin are mixed is provided on the pile surface thereof, when performing the punching process for forming the openings, the pile is embraced and the porous polyurethane resin is likely to shrink and deform. Therefore, it is easy to form an opening peripheral edge portion having a shape inclined so as to fall into the center of the opening. Further, by having an opening peripheral edge portion having such a sunken shape and forming it so that the pile does not protrude from the surface of the mixed layer, it is possible to suppress the fibers from protruding from the openings and improve the appearance. Furthermore, since the opening peripheral edge portion has a sunken shape, the opening is less likely to be rubbed. In addition, since the mixed layer contains not only pile but also a porous polyurethane resin, when an external force is applied during the use of the synthetic leather, the porous polyurethane resin can suppress the distortion on the surface of the synthetic leather. Therefore, in combination with having an opening peripheral edge portion having a sunken shape, the abrasion resistance can be improved.

[0013] FIG. 1 schematically shows a cross-sectional structure of a synthetic leather 1 according to an embodiment. The synthetic leather 1 includes a fibrous base material 2 and a resin layer 3 laminated on one side thereof. The fibrous base material 2 includes a warp knitted fabric 4 including a ground weave 41 and pile 42, and a mixed layer 6 in which the pile 42 and a porous polyurethane resin 5 are mixed between the ground weave 41 and the resin layer 3. That is, in this example, the fibrous base material 2 includes a mixed layer 6 in which a porous polyurethane resin 5 is laminated in a state of being mixed with the pile 42 on the pile surface side of the warp knitted fabric 4. And the resin layer 3 is laminated on the mixed layer 6.

[0014] FIG. 2 schematically shows a cross-sectional structure of a synthetic leather 10 according to another embodiment. This synthetic leather 10 is different from the synthetic leather 1 in FIG. 1 in that the resin layer 3 is composed of an adhesive layer 31, a surface layer 32, and a surface treatment layer 33. Therefore, in the example of FIG. 2, a mixed layer 6 in which a porous polyurethane resin 5 is laminated in a state of being mixed with the pile 42 is provided on the pile surface side of the warp knitted fabric 4, and the adhesive layer 31, the surface layer 32, and the surface treatment layer 33 are laminated in this order on the mixed layer 6.

[0015] In Figures 1 and 2, the surface (front) of the synthetic leather 1 and 10 (i.e., the surface (front) of the resin layer 3) is provided with multiple openings 7 to improve breathability. The openings 7 are provided by penetrating the fibrous base material 2 from the surface of the resin layer 3. In other words, the openings 7 are provided as holes that penetrate the resin layer 3 and the fibrous base material 2 (i.e., holes that penetrate the synthetic leather 1 and 10).

[0016] As shown in Figures 1 and 2, the multiple openings 7 are formed with an opening periphery 71 that is inclined such that the surface of the resin layer 3 slopes downward toward the center of the opening 7. More specifically, the opening 7 comprises an opening periphery 71 in which the resin layer 3 is tapered downward toward the center of the opening 7, and a penetration portion 72 that extends downward from its lower end and penetrates the resin layer 3 and the fibrous substrate 2. This inclined shape is mainly formed by the shrinkage of the thickness of the mixed layer 6 at the opening periphery 71.

[0017] The ridges 42 do not protrude from the surface of the mixed layer 6 (the surface on the resin layer 3 side). In other words, the ridges 42 do not protrude upward beyond the upper surface of the porous polyurethane resin 5. The entire region in the thickness direction of the fibrous substrate 2 where the ridges 42 exist is impregnated with the porous polyurethane resin 5.

[0018] In the examples shown in Figures 1 and 2, the surfaces of the synthetic leather 1 and 10 are flat, but for aesthetic reasons, uneven patterns such as a leather-like grain pattern may be provided according to conventional methods. Here, the surface of the synthetic leather refers to the side of the synthetic leather that is visible during use (the design side). Specifically, the surface of the synthetic leather is the surface of the resin layer described above.

[0019] In this embodiment, the fibrous base material includes, as described above, a warp-knitted fabric having a pile on its surface (hereinafter also referred to as a pile-knitted warp-knitted fabric), and a mixed layer provided on the pile-knitted surface of the warp-knitted fabric in which the pile and a porous polyurethane resin are mixed.

[0020] By using warp-knitted fabric, it is possible to obtain long, seamless pieces. Examples of warp-knitted fabrics include tricot knit and double raschel knit. Among these, tricot knit is preferred because it allows for easy adjustment of the pile state and enables the production of a dense pile.

[0021] The warp-knitted fabric may or may not be colored with dyes or pigments. The dyes or pigments used for coloring are not particularly limited.

[0022] The fiber material that makes up the warp-knitted fabric is not particularly limited, and conventionally known natural fibers, regenerated fibers, semi-synthetic fibers, synthetic fibers, etc., can be used. These can be used individually or in combination of two or more. Among these, synthetic fibers are preferred from the viewpoint of strength, and polyester fibers are more preferred.

[0023] Warp-knitted fabrics have a base fabric and raised fibers. Warp-knitted fabrics have raised fibers on at least one side. Preferably, the raised fibers are formed on only one side of the warp-knitted fabric. Here, the base fabric is the main body of the warp-knitted fabric that constitutes a predetermined knitting structure, and is also called the non-raised portion. The raised fibers are hairs (fluff) raised from the base fabric, and are also called the bristles. The raised fibers consist of fibers that make up the base fabric and are constrained by the knitting structure. Therefore, resistance to shedding and abrasion can be improved. The raised fibers can be formed, for example, by opening the knitting structure, napping, or flocking.

[0024] The length of the pile is not particularly limited, but is preferably 0.4 to 1.2 mm, and more preferably 0.6 to 0.8 mm. When the pile length is above the lower limit, it is easier to form the recessed shape of the opening periphery during the hole-punching process. When the pile length is below the upper limit, it is easier to suppress distortion of the synthetic leather surface caused by the movement of the pile when external force is applied during use, thereby improving abrasion resistance.

[0025] The length of the standing pile is measured as follows: Before measurement, the pile surface is stroked three times by hand in the reverse direction to make the pile stand up, and then the length of the standing pile (length from the base of the pile to the tip of the pile) is measured. The measurement is performed by observing the vertical cross section of the warp-knitted fabric with a microscope (for example, VHX-200 / 100F manufactured by Keyence Corporation) at 100x magnification, measuring the length of any 10 standing piles, and calculating the average value. Here, the reverse direction is the direction opposite to the forward direction, and the forward direction is the direction in which the standing pile is lying down.

[0026] The length of the pile in the fibrous substrate and synthetic leather after the formation of the mixed layer is measured as follows: The vertical cross-section of the fibrous substrate or synthetic leather is observed at 100x magnification using a microscope (for example, VHX-200 / 100F manufactured by Keyence Corporation), the length (length from the base of the hair to the tip of the hair) of any 10 piles is measured, and the average value is calculated.

[0027] The density of the standing hairs is not particularly limited, but is approximately 158,400 hairs / (25.4 mm). 2 ~244,800 strands (25.4mm) 2 It is preferable that the pile density is above the lower limit, which suppresses distortion of the synthetic leather surface due to external forces, thereby improving abrasion resistance. If the pile density is below the upper limit, it is easier to form the recessed shape of the opening periphery during the hole-punching process. In addition, the tensile strength and tear strength will be good.

[0028] The fineness (single fiber fineness) of the fibers constituting the pile is not particularly limited, but is preferably 0.5 to 2.2 dtex. If the single fiber fineness is above the lower limit, the synthetic leather will have a cushioning feel and a good texture. If the single fiber fineness is below the upper limit, it will be easier to form the recessed shape of the opening periphery during the hole-punching process.

[0029] The fineness (thread density) of the yarns constituting the warp-knitted fabric is not particularly limited, but is preferably between 55 and 110 dtex. A thread density above the lower limit improves tensile strength and tear strength. A thread density below the upper limit results in a good texture.

[0030] The density of the warp-knitted fabric is not particularly limited, but is preferably 55-68 courses / 25.4mm and 40-50 weels / 25.4mm, and more preferably 59-65 courses / 25.4mm and 44-48 weels / 25.4mm. A density of warp-knitted fabric above the lower limit improves tensile strength and tear strength. A density of warp-knitted fabric below the upper limit suppresses a decrease in elongation properties. Furthermore, the amount of yarn used can be reduced, resulting in cost savings.

[0031] The pile length, pile density, single fiber fineness, yarn fineness, and warp-knit fabric density mentioned above refer to the single fiber fineness, yarn fineness, and density of the warp-knit fabric before the application of the porous polyurethane resin. The pile length, pile density, single fiber fineness, yarn fineness, and warp-knit fabric density of the fibrous substrate and synthetic leather after the application of the porous polyurethane resin may be set within the same range.

[0032] The basis weight (mass per unit area) of warp-knitted fabric is set at 200-300 g / m² from the perspective of weight reduction. 2 It is preferable that this be the case.

[0033] The tensile strength of the warp-knitted fabric is not particularly limited. From the viewpoint of obtaining synthetic leather with strength suitable for use as an interior material for vehicles, it is preferable that the tensile strength in the warp and weft directions of the warp-knitted fabric be 100 N / cm or more. Here, the warp direction of the warp-knitted fabric refers to the direction in which the warp-knitted fabric is knitted, and the weft direction refers to the direction perpendicular to the warp direction.

[0034] The constant load elongation rate of the warp-knitted fabric is not particularly limited. From the viewpoint of obtaining synthetic leather with elongation characteristics suitable for vehicle interior material applications, it is preferable that the constant load elongation rate in the warp direction of the warp-knitted fabric is 10% or more, and the constant load elongation rate in the weft direction is 30% or more.

[0035] The above-mentioned mixed layer is a porous resin layer laminated in a state in which porous polyurethane resin and pile are mixed. Here, "mixing" means that the pile and porous polyurethane resin are intermingled by the porous polyurethane resin getting into the spaces between the numerous piles on the pile surface. For example, a mixed layer can be formed by impregnating the pile surface with porous polyurethane resin. Porous refers to a structure that has many fine pores (air bubbles). Furthermore, porous polyurethane resin refers to a polyurethane resin that has a porous structure, but this polyurethane resin may contain not only polyurethane as a polymer but also additives such as colorants, and even those containing such additives are simply called "porous polyurethane resin".

[0036] As described above, the bristles do not protrude from the surface of the mixed layer, and the entire region where the bristles exist in the thickness direction of the fibrous substrate is impregnated with porous polyurethane resin. Furthermore, it is preferable that there is substantially no layer of porous polyurethane resin without bristles on the surface of the mixed layer (the surface on the resin layer side). In other words, it is preferable that there is substantially no layer consisting solely of porous polyurethane resin beyond the tips of the bristles and above the bristles. A layer of porous polyurethane resin without bristles is more susceptible to breakage than the mixed layer because it is not reinforced by the bristles. Therefore, substantially eliminating a layer of porous polyurethane resin without bristles is advantageous in improving peel strength.

[0037] Here, the fact that there is substantially no layer of the porous polyurethane resin without pile means that there is no such layer without pile, or even if it exists, the thickness of the layer without pile is less than 50 μm. The thickness of the layer without pile is preferably less than 40 μm, more preferably 30 μm or less. In addition, the thickness of the layer without pile is measured at a portion where no opening is provided in the synthetic leather provided with an opening.

[0038] The thickness of the mixed layer is not particularly limited, and for example, it may be 0.4 to 1.2 mm, or may be 0.6 to 0.8 mm. In addition, the thickness of the mixed layer is measured at a portion where no opening is provided in the synthetic leather provided with an opening.

[0039] The thickness of the above-mentioned mixed layer and the thickness of the layer without pile can be measured as follows. Observe the vertical cross-section of the fibrous substrate or synthetic leather with a microscope (for example, VHX-200 / 100F manufactured by Keyence Corporation) at 200 times magnification, and obtain the distance T1 from the surface of the ground tissue 41 to the surface of the layer of the porous polyurethane resin 5, and the distance T2 from the surface of the ground tissue 41 to the tip of the pile 42 (see Figure 3). For any 5 locations, obtain the distances T1 and T2 and calculate the average values of T1 and T2 respectively. For the average value, when T1≧T2, T2 is taken as the thickness of the mixed layer, and when T1<T2, T1 is taken as the thickness of the mixed layer. Also, the difference between T1 and T2 when T1>T2, that is, T3 (=T1 - T2) is taken as the thickness of the above-mentioned layer without pile.

[0040] The above-mentioned mixed layer is preferably formed by wet coagulation of a solvent-based polyurethane resin on the pile surface of the warp knitted fabric. Wet coagulation means coagulating a solvent-based polyurethane resin solution in an aqueous medium such as water, and a microporous polyurethane resin having a continuous pore structure is formed. For example, at least the pile portion (the portion where pile exists) of the warp knitted fabric is impregnated with a solvent-based polyurethane resin solution and coagulated in an aqueous medium. Thereby, the gaps between the piles in the pile portion are filled with the porous polyurethane resin, and a mixed layer in which the piles and the porous polyurethane resin are mixed is formed.

[0041] In a fibrous substrate, the porous polyurethane resin may be present only in the mixed layer, or it may be impregnated into at least a part of the base fabric. In one embodiment, it is preferable that the porous polyurethane resin is impregnated into the entire warp-knitted fabric, i.e., the entire pile and the base fabric. This further enhances the effect of suppressing the escape of fibers cut by the perforation process from the openings.

[0042] In one embodiment, when porous polyurethane resin is impregnated into the entire warp-knitted fabric, the amount of porous polyurethane resin in the fibrous base material is not particularly limited, but is preferably 40 to 130% by mass, and more preferably 60 to 100% by mass, relative to the mass of the warp-knitted fabric. When the amount of porous polyurethane resin is above the lower limit, it is easier to suppress distortion of the synthetic leather surface caused by the movement of the pile when external force is applied during use. When the amount of porous polyurethane resin is below the upper limit, the amount of porous polyurethane resin used can be reduced, resulting in cost savings. In addition, during the hole-punching process, a shrinking force is generated in the porous polyurethane resin, making it easier to form an opening periphery with a sloping shape so that the mixed layer falls towards the center of the opening.

[0043] Specific examples of polyurethane as a polymer constituting porous polyurethane resin include polycarbonate-based polyurethane resin, polyether-based polyurethane resin, and polyester-based polyurethane resin. These polyurethane resins can be used individually or in combination of two or more. Among these, polycarbonate-based polyurethane resin is preferred from the viewpoint of chemical resistance, and polyether-based polyurethane resin is preferred from the viewpoint of texture. In one embodiment, from the viewpoint of low-temperature flexibility, it is preferable to use polyether-based polyurethane resin as the main component, for example, it is preferable that 50% by mass or more of the polyurethane is polyether-based polyurethane resin.

[0044] Porous polyurethane resin may, if necessary, contain conventionally known additives such as colorants, plasticizers, stabilizers, fillers, lubricants, etc.

[0045] Furthermore, if the porous polyurethane resin constituting the mixed layer has the interconnected pore structure described above, some of the resin constituting the resin layer, such as the adhesive layer described later, may seep into the surface of the mixed layer, and such a configuration is also included in this embodiment.

[0046] The basis weight (mass per unit area) of the fibrous base material is set at 280-690 g / m² from the perspective of weight reduction. 2 Preferably, it is less than 300-400 g / m². 2 The following applies:

[0047] The tensile strength of the fibrous base material is not particularly limited. However, from the viewpoint of obtaining strength suitable for use as an interior material for vehicles, it is preferable that the tensile strength of the fibrous base material in the warp and weft directions be 100 N / cm or more.

[0048] The constant-load elongation rate of the fibrous base material is not particularly limited. From the viewpoint of obtaining elongation characteristics suitable for use as an interior material for vehicles, it is preferable that the constant-load elongation rate of the fibrous base material in the longitudinal direction is 5% or more, and the constant-load elongation rate in the latitudinal direction is 30% or more.

[0049] As described above, the synthetic leather according to this embodiment comprises a resin layer provided on a fibrous substrate. The resin layer may be porous or non-porous. From the viewpoint of abrasion resistance, it is preferable that at least the outermost layer is non-porous. Here, non-porous means a structure that does not have fine pores (air bubbles).

[0050] The resin that makes up the resin layer is not particularly limited, and examples include polyurethane resin and acrylic resin. These resins can be used individually or in combination of two or more. Among these, polyurethane resin is preferred from the viewpoint of low-temperature flexibility, cold resistance and texture.

[0051] The polyurethane resin is not particularly limited, and examples include polyether-based polyurethane resins, polyester-based polyurethane resins, and polycarbonate-based polyurethane resins. These polyurethane resins can be used individually or in combination of two or more types.

[0052] The form of the polyurethane resin is not particularly limited and can be appropriately selected depending on the application. For example, it may be solvent-free, hot-melt, solvent-based, or water-based, and may be one-component or two-component curing type.

[0053] The polyurethane resin may contain, as needed, conventionally known additives such as colorants, plasticizers, stabilizers, fillers, lubricants, foaming agents, and mold release agents. These can be used individually or in combination of two or more.

[0054] The thickness of the resin layer is preferably 90 to 200 μm, and more preferably 130 to 170 μm. A resin layer thickness above the lower limit results in good wear resistance. A resin layer thickness below the upper limit makes it easier to form the recessed shape of the opening periphery during drilling. If the resin layer consists of multiple resin layers, the thickness of the resin layer is the sum of the thicknesses of the multiple resin layers. For example, as shown in Figure 2, if the resin layer includes a surface treatment layer, a surface layer, and an adhesive layer, the thickness of the resin layer is the sum of the thicknesses of the surface treatment layer, surface layer, and adhesive layer.

[0055] The thickness of the resin layer in synthetic leather is measured as follows: The vertical cross-section of the synthetic leather is observed at 100x magnification using a microscope (for example, VHX-200 / 100F manufactured by Keyence Corporation), the thickness of the layer is measured at 10 arbitrary locations, and the average value is calculated.

[0056] The resin layer consists of at least one resin layer, but can be composed of two or more resin layers of the same or different compositions. Preferably, the resin layer includes an adhesive layer, a surface layer, and a surface treatment layer in that order on a fibrous substrate. Here, the surface layer is a resin layer for coloring to a desired color. The surface treatment layer is a resin layer for imparting a desired feel, appearance (gloss), and durability (abrasion resistance) to the synthetic leather. The surface treatment layer is a general term for resin layers that are formed on the surface of the surface layer and serve as the outermost layer protecting the surface layer. The surface layer and the surface treatment layer each consist of at least one resin layer, but can be composed of two or more resin layers of the same or different compositions.

[0057] From the viewpoint of texture, polyurethane resin is preferred for the resin constituting the surface treatment layer. From the viewpoint of abrasion resistance, the polyurethane resin preferably includes polycarbonate-based polyurethane resin. More preferably, the polyurethane resin constituting the surface treatment layer consists solely of polycarbonate-based polyurethane resin, however, additives such as smoothing agents, antifouling agents, and antibacterial agents may be optionally included.

[0058] The thickness of the surface treatment layer is not particularly limited, but is preferably 10 to 20 μm, and more preferably 10 to 15 μm. A surface treatment layer thickness greater than or equal to the lower limit results in good wear resistance. A surface treatment layer thickness less than or equal to the upper limit results in good bending resistance.

[0059] From the viewpoint of texture, polyurethane resin is preferred for the resin constituting the surface layer. From the viewpoint of durability, it is preferable that the polyurethane resin includes polycarbonate-based polyurethane resin. More preferably, the proportion of polycarbonate-based polyurethane resin in the polyurethane resin constituting the surface layer is 30% by mass or more.

[0060] The thickness of the surface layer is not particularly limited, but is preferably 30 to 60 μm, and more preferably 45 to 55 μm. A surface layer thickness above the lower limit results in good abrasion resistance. A surface layer thickness below the upper limit results in a lightweight synthetic leather.

[0061] From the viewpoint of texture, polyurethane resin is preferred as the resin constituting the adhesive layer. The polyurethane resin is not particularly limited, and examples include polyether-based polyurethane resin, polyester-based polyurethane resin, and polycarbonate-based polyurethane resin. These polyurethane resins can be used individually or in combination of two or more.

[0062] The thickness of the adhesive layer is not particularly limited, but is preferably 50 to 120 μm, and more preferably 75 to 100 μm. A thickness of the adhesive layer above the lower limit results in good abrasion resistance. A thickness of the adhesive layer below the upper limit results in a lightweight synthetic leather.

[0063] The synthetic leather according to this embodiment has a plurality of openings, as described above. The openings can be formed by conventionally known means such as needle punching. The openings are holes that penetrate from the surface of the resin layer to the fibrous substrate.

[0064] The opening has an opening periphery that is shaped so that the surface of the resin layer slopes downward toward the center of the opening. The opening angle of the opening periphery is not particularly limited and may be 100° to 170°, 110° to 165°, or 125° to 160°. Here, the opening angle of the opening periphery is the taper angle θ of the tapered opening periphery 71, as shown in Figures 1 and 2.

[0065] The depth of the opening periphery is not particularly limited and may be 5 to 225 μm or 30 to 110 μm. Here, the depth of the opening periphery is the depth H from the surface of the synthetic leather to the lower end of the tapered opening periphery 71, as shown in Figures 1 and 2.

[0066] Here, the opening angle and depth of the opening peripheral part can be obtained as follows. That is, the vertical cross-section of the synthetic leather is magnified 200 times with a microscope (for example, VHX-200 / 100F manufactured by Keyence Corporation) and observed to measure the opening angle and depth of the opening peripheral part. The opening angle and depth are measured at any five locations, and the average value is calculated.

[0067] The aperture ratio, which is the ratio (area ratio) occupied by the openings on the surface of the synthetic leather (i.e., the surface of the resin layer), is not particularly limited, but is preferably 5 to 13%. When the aperture ratio is at least the lower limit value, sufficient air permeability to eliminate stuffiness and stickiness can be obtained. On the other hand, when the aperture ratio is at most the upper limit value, it is excellent in terms of abrasion resistance, elongation, and strength. The aperture ratio is more preferably 5 to 12%, and even more preferably 5 to 8%. Here, the aperture ratio is the ratio of the total area of a plurality of openings (including not only through-holes but also openings including the opening peripheral part) existing in the surface to the total area of the surface including the openings when the surface of the synthetic leather is viewed planar.

[0068] The shape of the openings is not particularly limited, and it is possible to select from geometric patterns such as circles, triangles, and squares in consideration of design. From the perspective of durability, a circle is preferred. Also, the size of the openings is not particularly limited, for example, 0.60 to 1.30 mm 2 is also acceptable, and 0.64 to 1.14 mm 2 is also acceptable. Here, the size of the openings is the area of the openings on the surface of the synthetic leather, and when the shape of the openings is circular, it is the area calculated using the symbol D shown in FIGS. 1 and 2 as the opening diameter.

[0069] The air permeability of the synthetic leather according to this embodiment is preferably 58 cm 3 / cm 2 / s or more. When the air permeability is at least the lower limit value, sufficient air permeability to eliminate stuffiness and stickiness can be obtained.

[0070] The constant-load elongation rate of the synthetic leather according to this embodiment is preferably 10% or more in both the warp and weft directions, and more preferably 14% or more in both the warp and weft directions. Since the constant-load elongation rate is above the lower limit in both the warp and weft directions, suitable elongation characteristics for vehicle interior material applications are obtained. Therefore, wrinkles are less likely to occur when the synthetic leather is upholstered onto a seat, resulting in a synthetic leather with good upholstery properties. Here, the warp and weft directions of the synthetic leather are the same as those of the warp-knitted fabric.

[0071] The tear strength of the synthetic leather according to this embodiment is preferably 20 N or more in both the warp and weft directions, and more preferably 22 N or more in both directions. A tear strength above the lower limit in both the warp and weft directions satisfies sufficient strength for vehicle interior material applications and improves durability. The upper limit is not particularly limited, but is preferably 40 N or less.

[0072] The tensile strength of the synthetic leather according to this embodiment is preferably 50 N / cm or more in both the warp and weft directions, and more preferably 55 N / cm or more in both directions. Having a tensile strength above the lower limit in both the warp and weft directions satisfies sufficient strength for vehicle interior material applications and improves durability. The upper limit is not particularly limited, but is preferably 80 N / cm or less.

[0073] Next, a method for manufacturing synthetic leather will be described. The manufacturing method is not particularly limited, and in one embodiment, synthetic leather according to the embodiment can be manufactured by performing the following steps in order. That is, the manufacturing method is (1) The process of raising the nap of the warp-knitted fabric to form a pile, (2) A process of adjusting the pile warp knitted fabric to a desired density, (3) A process of wet impregnating a pile warp knitted fabric with a solvent-based polyurethane resin to obtain a fibrous base material, (4) A step of applying a resin liquid for the resin layer onto a release substrate to form a resin layer, (5) A process of bonding the resin layer and the fibrous substrate, (6) A step of peeling off the release material, (7) The process of drilling holes, Includes.

[0074] In step (1), the method for raising the nap of the warp-knitted fabric is not particularly limited, and examples include napping with a needle cloth or napping with sandpaper. In the case of napping with a needle cloth, the state of the raised nap can be appropriately set by selecting various conditions such as the density, length, angle, and tip shape of the needle cloth, the number of rotations of the needle cloth during napping, the contact pressure with the fibrous base material, and the number of contacts. Similarly, in napping with emery, the state of the raised nap can be appropriately set by selecting various conditions such as the paper mesh of the sandpaper and the number of contacts between the sandpaper and the fibrous base material during napping. If necessary, a nap straightening process may be provided after napping to adjust the nap.

[0075] In step (2), there are no particular limitations on the method for adjusting the pile warp-knitted fabric to a desired density. For example, it is preferable to perform so-called widthening and / or widthening in a heat treatment process such as heat setting. Specifically, by heat-treating the pile warp-knitted fabric fixed to a desired width at 90 to 150°C for 2 to 6 minutes, a pile warp-knitted fabric with a desired density (55 to 68 courses / 25.4 mm, 40 to 50 wells / 25.4 mm) can be obtained.

[0076] In step (3), a method for wet impregnating the pile warp-knitted fabric with a solvent-based polyurethane resin includes applying a solvent-based polyurethane resin solution to the pile warp-knitted fabric and immersing it in an aqueous medium to allow it to solidify, thereby obtaining a fibrous base material containing a mixed layer. By wet impregnation in this manner, it is possible to sufficiently restrain the pile while preventing the texture from becoming stiff.

[0077] For example, one method involves dipping a piled warp-knitted fabric into a solvent-based polyurethane resin solution, and then passing the dipped fabric through a coater with adjusted clearance to ensure a constant coating amount, thereby scraping off any excess solvent-based polyurethane resin solution. This prevents the pile from protruding from the surface of the mixed layer, and ensures that there is substantially no layer consisting solely of porous polyurethane resin on the surface of the mixed layer. Subsequently, the piled warp-knitted fabric impregnated with the solvent-based polyurethane resin solution is immersed in an aqueous medium such as water. This removes the solvent in the solvent-based polyurethane resin solution contained in the piled warp-knitted fabric by replacement with water (desolvation), and the polyurethane resin in the solvent-based polyurethane resin solution solidifies.

[0078] Next, a fibrous base material is produced by drying the piled warp-knitted fabric in which the polyurethane resin has been solidified. For example, a fibrous base material is produced by dewatering the piled warp-knitted fabric containing the solidified porous polyurethane resin and water using a mangle, and then drying it under hot air at 100°C to 120°C.

[0079] In step (4), various conventionally known methods can be used to apply the resin liquid for the resin layer onto the release substrate, and are not particularly limited. For example, methods using equipment such as a comma coater, reverse roll coater, spray coater, roll coater, and knife coater can be used. Among these, application by a comma coater or knife coater is preferred because it enables the formation of a uniform thin film layer. The coating thickness of the resin liquid for the resin layer can be set as appropriate as needed.

[0080] The release material is not particularly limited and can be any material that has release properties to resin, or a material that has been treated with a release agent. Examples of release materials include release paper, release treated cloth, water-repellent treated cloth, olefin sheets or films made of polyethylene resin or polypropylene resin, fluororesin sheets or films, and plastic films with release paper. The release material may have an uneven pattern, and by using such a release material, it is possible to impart design features to the surface of synthetic leather.

[0081] After applying the resin liquid for the resin layer to the release substrate, heat treatment is performed as necessary. The heat treatment is performed to evaporate the solvent in the resin liquid for the resin layer and dry the resin. In addition, when using a crosslinking agent that causes a crosslinking reaction by heat treatment, or when using a two-component curing type resin, heat treatment is performed to accelerate the reaction and form a film with sufficient strength.

[0082] Next, in step (5), the resin layer and the fibrous substrate are bonded together. Methods for bonding include conventionally known methods such as transfer bonding, heat fusion, heat compression bonding, and adhesive bonding. When using an adhesive (to form an adhesive layer), the adhesive is applied to the resin layer before bonding the fibrous substrate. Various known methods can be used for applying the adhesive, and are not particularly limited. For example, methods using equipment such as a comma coater, reverse roll coater, spray coater, roll coater, gravure coater, kiss roll coater, and knife coater can be used.

[0083] Next, in step (6), the release agent is peeled off from the resin layer. By peeling off the release agent, a laminate of the resin layer and the fibrous substrate is obtained.

[0084] When forming multiple resin layers, one method involves forming the resin layers on a release substrate, and then applying a resin liquid for the resin layer to the surface of the resin layer before applying the adhesive. For example, when forming an adhesive layer, a surface layer, and a surface treatment layer as resin layers, in step (6), the release substrate may be peeled off to obtain a laminate of the surface layer, adhesive layer, and fibrous substrate, and then a resin liquid for the surface treatment layer may be applied to the surface of the surface layer.

[0085] Various conventionally known methods can be used to apply the resin liquid for the surface treatment layer to the surface layer in order to form the surface treatment layer, and are not particularly limited. For example, methods using equipment such as rotary screen printers, reverse roll coaters, spray coaters, roll coaters, gravure coaters, kiss roll coaters, knife coaters, and comma coaters can be used. Among these, application by rotary screen printers and reverse roll coaters is preferred because it is possible to form a uniform thin film layer. The coating thickness of the resin liquid for the surface treatment layer should be set appropriately according to the required thickness of the surface treatment layer. Subsequently, heat treatment may be performed if necessary.

[0086] Next, in step (7), a hole-punching process is carried out to form a plurality of openings. The hole-punching process is not particularly limited, and conventionally known methods such as needle punching can be used. Thus, the synthetic leather according to the embodiment is obtained.

[0087] The uses of the synthetic leather according to this embodiment are not particularly limited, but it can be used for various interior materials for vehicles, such as car seats, ceiling materials, dashboards, door trims, or steering wheels.

[0088] Furthermore, the various numerical ranges described in this specification can be any combination of their upper and lower limits, and all such combinations are described herein as preferred numerical ranges. Also, the description of a numerical range as "X~Y" means X or greater and Y or less. [Examples]

[0089] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0090] Each evaluation item was assessed according to the following method.

[0091] [Air permeability] The air permeability was measured at room temperature (23°C) in accordance with JIS L1096:2010 8.26.1 Method A (Fragile method). A higher measured value indicates higher air permeability.

[0092] [Tensile strength] Tensile strength is defined as the value (N / cm) obtained by dividing the maximum load (N) until the test specimen breaks under tension in the following tensile test by the width (cm) of the test specimen. Specifically, three test specimens, each 50 mm wide and 300 mm long, were taken from both the warp and weft directions. Under conditions of room temperature 20±2℃ and humidity 65±5%RH, both ends of the test specimen were clamped tightly with grips, and the maximum load (N) until the test specimen broke was measured using a tensile testing machine Autograph AG-100A (manufactured by Shimadzu Corporation) with a grip width of 50 mm, a grip spacing of 200 mm, and a grip movement speed of 200 mm / min. The maximum load (N) until the test specimen broke was measured, and this was divided by the width of the test specimen (50 mm) to obtain the maximum load per unit width (N / cm), and the average value was calculated. If the average tensile strength of synthetic leather is 50 N / cm or higher, it can be said that it has sufficient tensile strength for use as a vehicle interior material, and the higher the value, the better the tensile strength.

[0093] [Tear strength] Tear strength is defined as the maximum load (N) required to break the test specimen in the following tear test. Specifically, three test specimens, each 40 mm wide and 150 mm long, were taken from both the warp and weft directions. A 75 mm long cut was made in each specimen, running parallel to the long side from the center of the short side. Under conditions of room temperature (20 ± 2°C) and humidity (65 ± 5% RH), a tensile testing machine, Autograph AG-100A (manufactured by Shimadzu Corporation), was used. The cut side of the test specimen was attached to a pair of grips with the front and back sides reversed and a gripping distance of 10 mm, and the specimen was torn at a moving speed of 200 mm / min. The maximum load (N) required to break the test specimen was measured, and the average value was calculated. An average tear strength of 20 N or more for synthetic leather is considered sufficient for use as an interior material in vehicles, and a higher value indicates superior tear strength.

[0094] [Constant load elongation rate] Measurements were taken in accordance with JIS L1096:2010 8.16 Method D. Specifically, three test specimens, each 50 mm wide and 250 mm long, were taken from both the warp and weft directions. Gauge marks were marked at 100 mm intervals along the length of each specimen, centered in the longitudinal direction. Under conditions of room temperature 20 ± 2°C and humidity 65 ± 5% RH, the specimens were mounted tautly on the grips of a constant load elongation test apparatus (Martens type) (manufactured by Shilian Automotive Interior (Suzhou) Co., Ltd.) with a grip spacing of 150 mm. A load of 78.4 N was applied to the lower grips, including the lower grips. The distance between the gauge marks (L) was measured after 10 minutes, and the constant load elongation rate (%) was calculated using the following formula. The average values ​​were calculated for both the warp and weft directions. If the average constant-load elongation rate of synthetic leather is 10% or more in both the warp and weft directions, it can be said to have suitable elongation characteristics for use as a vehicle interior material and to be a synthetic leather with good tension properties. Constant load elongation rate (%) = L - 100

[0095] [Peel strength] The peel strength is defined as the value (N / cm) obtained by dividing the maximum load (N) required to peel the test specimen by the width (cm) of the test specimen in the following peel test. Specifically, three test specimens, each 30 mm wide and 120 mm long, were taken from both the warp and weft directions. The resin layer and fibrous base material were peeled 40 mm from one end of the short side of the test specimen. Under conditions of room temperature 20±2℃ and humidity 65±5%RH, the resin layer and fibrous base material were held tautly with grips, and the resin layer was peeled using a tensile testing machine Autograph AG-100A (manufactured by Shimadzu Corporation) with a grip width of 30 mm and a grip movement speed of 200 mm / min. The maximum load (N / cm) at the time of peeling was measured, and the average value was taken as the peel strength. A measured value of 5 N / cm or higher indicates sufficient peel strength for synthetic leather, and a higher value indicates superior peel strength.

[0096] [Abrasion resistance] One piece of cotton canvas (equivalent to JIS L 3102 No. 6) measuring 30 mm in width and 250 mm in length was taken from the weft direction and fixed to a JSPS-type abrasion tester RT-300S (manufactured by Daiei Kagaku Seiki Seisakusho Co., Ltd.). After taking one test piece measuring 10 mm in width and 100 mm in length from both the warp and weft directions, a material measuring 10 mm in width and 100 mm in length with a density of 0.030 g / cm³ was applied to the back side. 3 A friction element was fabricated by attaching a 4mm thick urethane foam sheet. A load of 9.8N was applied to the friction element to rub against cotton canvas. The friction element was moved back and forth a maximum of 30,000 times at a speed of 30 back-and-forth cycles per minute over a distance of 100mm above the surface of the cotton canvas. The number of wear cycles until the test piece broke was confirmed and judged according to the following criteria. (Judgment criteria) A: Over 30,000 times B: 20,000 times or more, less than 30,000 times C: Less than 20,000 times

[0097] [Example 1] Using a 32-gauge tricot knitting machine with two reeds, the back side was knitted with 75dtex / 36f polyester multifilament yarn in a 1-0 / 1-2 denbi knit structure, and the front side was knitted with 75dtex / 36f polyester multifilament yarn in a 1-0 / 3-4 cord knit structure. The fabric was then knitted on the machine to a width of 165cm and 62 courses / 25.4mm to obtain a tricot knitted fabric.

[0098] Next, the sinker loop surface of the tricot knit fabric was subjected to a napping treatment. The napping treatment was performed using a needle fabric napping machine equipped with three needle fabric rolls, each having 12 pile rollers and 12 counterpile rollers. The needle fabric roller torque was 2.5 MPa and the fabric speed was 12 m / min, and the napping was performed 13 times alternately from the end direction and the beginning direction of knitting, resulting in a napped surface of the knit fabric.

[0099] Next, using a heat setter, the fabric was heat-treated in sections 1 (90°C, 7.5m), 2 (120°C, 7.5m), 3 (150°C, 7.5m), and 4 (140°C, 7.5m) with a pin width of 150cm at a rate of 5.5m / min to obtain a pile warp-knitted fabric. The pile warp-knitted fabric has a weight of 225g / m².2 This is a tricot knit fabric, with a fiber fineness (single fiber fineness) of 2.08 dtex and a pile density of 205,344 fibers / (25.4 mm). 2 The pile length was 0.7 mm, density was 62 courses / 25.4 mm and 46 wells / 25.4 mm, tensile strength was 110 N / cm in the warp direction and 116 N / cm in the weft direction, and constant load elongation was 17% in the warp direction and 50% in the weft direction. Here, the density of the pile was calculated as (number of filaments of napped yarn) × (course density) × (well density) × 2, since it was a full-cut napped yarn.

[0100] A solvent-based polyurethane resin solution was prepared by adding dimethylformamide solution to a polyether-based polyurethane resin so that the solid content was 23% by mass. After dipping a pile warp-knitted fabric into this resin solution, the excess resin solution was scraped off by passing it through a knife coater with a clearance adjusted to 1.0 mm. Next, the pile warp-knitted fabric impregnated with the resin solution was immersed in a 20% by mass aqueous solution of dimethylformamide to solidify the polyurethane resin. After dewatering with a mangle, the fabric was heat-treated using a heat setter at a rate of 5.0 m / min for sections 1 (90°C, 5 m), 2 (120°C, 5 m), 3 (150°C, 5 m), and 4 (140°C, 5 m) with a pin width of 145 cm, to obtain a fibrous substrate coated with porous polyurethane resin. The resulting fibrous substrate had a pile length of 0.7 mm, a mixed layer thickness of 0.7 mm, a density of 62 courses / 25.4 mm and 46 wells / 25.4 mm, tensile strength: 129 N / cm in the warp direction and 108 N / cm in the weft direction, constant load elongation: 10% in the warp direction and 62% in the weft direction, and a basis weight of 376 g / m². 2 The amount of porous polyurethane resin impregnating the fibrous substrate was 67% by mass relative to the mass of the napped warp-knitted fabric. No pile protruding from the surface of the mixed layer was observed in the fibrous substrate. Furthermore, the thickness of the porous polyurethane resin layer without pile on the mixed layer was 30 μm.

[0101] A surface resin solution was prepared by adding 84 parts by mass of dimethylformamide, 7 parts by mass of isopropyl alcohol, 33.5 parts by mass of methyl ethyl ketone, and 4 parts by mass of pigment to 34 parts by mass of polycarbonate polyurethane resin and adjusting the viscosity to approximately 2500 mPa·s. The surface resin solution was coated onto release paper using a comma coater to a coating thickness of 50 μm after drying, and then dried at 130°C for 2 minutes to form the surface layer.

[0102] To 36 parts by mass of polyether polyurethane resin and 9 parts by mass of polyester polyurethane resin, 85 parts by mass of dimethylformamide, 30 parts by mass of methyl ethyl ketone, 10 parts by mass of flame retardant, 2 parts by mass of curing agent, and 0.1 parts by mass of pigment were added, and the viscosity was adjusted to approximately 5000 mPa·s to prepare an adhesive. The adhesive was coated onto the surface layer formed above using a comma coater so that the coating thickness after drying was 100 μm, and then dried at 60°C for 2 minutes to form an adhesive layer. The obtained adhesive layer and the fibrous substrate were combined and pressed together under 0.3 MPa conditions for 1 second to obtain a laminate.

[0103] The laminate was peeled from the release substrate, and a resin solution for the surface treatment layer was coated onto the surface of the surface layer using a reverse roll coater so that the coating thickness after drying was 13 μm. As the resin solution for the surface treatment layer, a dimethylformamide solution prepared so that the solid content of the polycarbonate-based polyurethane resin was 20% by mass was used. After the above coating, it was dried at 130°C for 2 minutes to form a surface treatment layer on the surface layer, and synthetic leather was obtained.

[0104] The obtained synthetic leather was punched using a punching machine, with holes punched on the surface side. The punching was performed by placing punching pins with a hole diameter (inner diameter) of 1.0 mm at intervals of 5 mm (distance between the centers of the pins) in both the vertical and horizontal directions. This resulted in synthetic leather having multiple openings, each with an opening periphery that slopes downwards towards the center of the opening. In the obtained synthetic leather, the average opening diameter of the openings on the resin layer surface was 1.05 mm, the opening ratio was 6.9%, the opening angle of the opening periphery was 156°, and the depth of the opening periphery was 75.4 μm. Furthermore, when the thickness of each part of the resin layer in the obtained synthetic leather was measured, the thickness of the surface treatment layer was 13 μm, the thickness of the surface layer was 50 μm, the thickness of the adhesive layer was 80 μm, and the total thickness of the resin layer was 143 μm.

[0105] The breathability of synthetic leather is 66 cm. 3 / cm 2 The material had a viscosity rating of / s, which eliminated stuffiness and stickiness when used for extended periods as an interior material for vehicles. Furthermore, its tensile strength was 71 N / cm in the warp direction and 69 N / cm in the weft direction, its tear strength was 23 N in the warp direction and 26 N in the weft direction, its constant load elongation was 15% in the warp direction and 68% in the weft direction, and its peel strength was 7 N / cm in the warp direction and 8 N / cm in the weft direction, demonstrating sufficient strength and elongation characteristics suitable for vehicle interior material applications. In addition, its abrasion resistance was rated A in both the warp and weft directions, indicating excellent abrasion resistance for vehicle interior material applications. Moreover, there was no fiber protrusion from the openings, resulting in a superior appearance. When this synthetic leather was upholstered in a vehicle seat, wrinkle formation was suppressed, and it exhibited excellent upholstery.

[0106] [Example 2] Regarding the hole punching conditions using a punching machine, the hole diameter of the punching pins was set to 1.2 mm, and their arrangement was changed to a 4.5 mm interval in both the vertical and horizontal directions, thereby changing the opening ratio of the synthetic leather to 12.1%. The synthetic leather of Example 2 was obtained by otherwise performing the same procedure as in Example 1.

[0107] In the obtained synthetic leather, the average opening diameter of the openings on the resin layer surface was 1.25 mm, the opening ratio was 12.1%, the opening angle of the opening periphery was 140°, and the depth of the opening periphery was 105.3 μm. The air permeability of the synthetic leather was 124 cm². 3 / cm 2 The breathability was higher than in Example 1, with a value of / s. The tensile strength was 55 N / cm in the warp direction and 51 N / cm in the weft direction, the tear strength was 22 N in both the warp and weft directions, and the peel strength was 6 N / cm in both the warp and weft directions. Although the strength was lower than in Example 1, it had sufficient strength for use as a vehicle interior material. Furthermore, the constant load elongation was 24% in the warp direction and 70% in the weft direction, exhibiting elongation characteristics suitable for vehicle interior material use. In addition, the abrasion resistance was evaluated as B in both the warp and weft directions, which was inferior to Example 1, but still excellent for use as a vehicle interior material. Moreover, there was no fiber protrusion from the openings, resulting in a superior appearance. When this synthetic leather was upholstered in a vehicle seat, wrinkle formation was suppressed, and the upholstery was excellent.

[0108] [Comparative Example 1] A synthetic leather of Comparative Example 1 was obtained in the same manner as in Example 1, except that no napping treatment was applied. Specifically, the tricot knit fabric of Example 1 (knitted on the machine to a width of 165 cm and 62 courses / 25.4 mm) was subjected to density adjustment by heat setting without napping treatment. A porous polyurethane resin was impregnated into the obtained warp-knitted fabric in the same manner as in Example 1 to produce a fibrous base material. The obtained fibrous base material had a density of 56 courses / 25.4 mm, 42 wells / 25.4 mm, tensile strength: warp direction 208 N / cm, weft direction 197 N / cm, constant load elongation: warp direction 15%, weft direction 70%, and basis weight 281 g / m 2 The amount of porous polyurethane resin impregnating the fibrous substrate was 52% by mass relative to the mass of the warp-knitted fabric. In the fibrous substrate, a porous polyurethane resin layer with a thickness of 20 μm was formed on the warp-knitted fabric, but no mixed layer was formed.

[0109] A synthetic leather of Comparative Example 1 was obtained by forming a resin layer on the above fibrous substrate in the same manner as in Example 1 and then performing a perforation process. In the obtained synthetic leather, the average opening diameter of the openings on the surface of the resin layer was 1.0 mm, the opening ratio was 6.3%, and no peripheral openings were formed. The air permeability of the synthetic leather was 68 cm². 3 / cm 2 The breathability was 20% in the warp direction and 72% in the weft direction, indicating sufficient breathability for vehicle interior material applications, similar to Example 1. The tensile strength was 93 N / cm in the warp direction and 86 N / cm in the weft direction, the tear strength was 27 N in both the warp and weft directions, and the peel strength was 11 N / cm in both the warp and weft directions, indicating higher strength than Example 1. Furthermore, the constant load elongation was 20% in the warp direction and 72% in the weft direction, indicating elongation characteristics suitable for vehicle interior material applications. However, the abrasion resistance was evaluated as C in both the warp and weft directions, indicating poor abrasion resistance for vehicle interior material applications. In addition, there was no fiber protrusion from the openings, resulting in an excellent appearance.

[0110] [Comparative Example 2] A synthetic leather of Comparative Example 2 was obtained in the same manner as in Example 1, except that the mixed layer of fibrous base material was buffed with an emery napping machine to make the pile protrude 0.1 mm above the mixed layer. Specifically, in Example 1, a porous polyurethane resin was impregnated and then the mixed layer was buffed. The resulting fibrous base material had a pile length of 0.7 mm, a mixed layer thickness of 0.6 mm, a density of 62 courses / 25.4 mm, 46 wells / 25.4 mm, tensile strength: 118 N / cm in the warp direction, 102 N / cm in the weft direction, constant load elongation: 13% in the warp direction, 68% in the weft direction, and a basis weight of 293 g / m². 2 The amount of porous polyurethane resin impregnated into the fibrous substrate was 62% by mass relative to the mass of the napped warp-knitted fabric. In the fibrous substrate, the nap protruded 0.1 μm from the surface of the mixed layer.

[0111] A synthetic leather of Comparative Example 2 was obtained by forming a resin layer on the above fibrous substrate in the same manner as in Example 1 and then performing a perforation process. In the obtained synthetic leather, the average opening diameter of the openings on the surface of the resin layer was 1.05 mm, the opening ratio was 6.9%, the opening angle of the opening periphery was 158°, and the depth of the opening periphery was 72.6 μm. The air permeability of the synthetic leather was 60 cm². 3 / cm 2 The air permeability was lower than in Example 1, but still sufficient for use as a vehicle interior material. The tensile strength was 66 N / cm in the warp direction and 62 N / cm in the weft direction, and the tear strength was 21 N in the warp direction and 23 N in the weft direction, which was lower than in Example 1. The constant load elongation was 19% in the warp direction and 73% in the weft direction, which had elongation characteristics suitable for use as a vehicle interior material. The abrasion resistance was evaluated as B in both the warp and weft directions. However, there was some fiber protrusion from the openings, resulting in a poor appearance.

[0112] Table 1 summarizes the configurations and results of Examples 1 and 2 and Comparative Examples 1 and 2. [Table 1] [Explanation of Symbols]

[0113] 1. 10... Synthetic leather, 2... Fibrous base material, 3... Resin layer, 31... Adhesive layer, 32... Surface layer, 33... Surface treatment layer, 4... Warp knitted fabric, 41... Base fabric, 42... Raised pile, 5... Porous polyurethane resin, 6... Mixed layer, 7... Opening, 71... Peripheral edge of opening, 72... Penetration part

Claims

1. A synthetic leather comprising a fibrous base material and a resin layer provided on the fibrous base material, Multiple openings are provided that penetrate the fibrous substrate from the surface of the resin layer. The plurality of openings have an opening periphery that is inclined such that the surface of the resin layer slopes downward toward the center of the opening. The fibrous base material is Warp knitted fabric including ground fabric and standing pile, The device comprises a mixed layer provided between the base structure and the resin layer, in which the bristles and porous polyurethane resin are mixed, The bristles do not protrude from the surface of the mixed layer on the resin layer side. Synthetic leather.

2. The synthetic leather according to claim 1, wherein the layer of porous polyurethane resin without the pile is substantially absent on the resin layer side of the mixed layer, where substantially absent means that the layer without the pile is absent or, if present, the thickness of the layer without the pile is less than 50 μm.

3. The synthetic leather according to claim 1 or 2, wherein the thickness of the resin layer is 90 to 200 μm.

4. The synthetic leather according to claim 1 or 2, wherein the opening ratio on the surface of the synthetic leather is 5 to 13%.

5. The synthetic leather according to claim 1 or 2, wherein the porous polyurethane resin is impregnated into at least a portion of the base material in the fibrous base material.

6. The synthetic leather according to claim 1 or 2, wherein the resin layer comprises, in this order, an adhesive layer, a surface layer, and a surface treatment layer on the fibrous substrate.

7. The synthetic leather according to claim 1 or 2, wherein the thickness of the mixed layer is 0.4 to 1.2 mm.

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