Napped Leather-Like Sheet-Shaped Article

The present invention relates to a napped leather-like sheet-shaped article.

Leather-like sheet-shaped articles have been used for, for example, vehicle interior material applications such as vehicle seats and door linings, interior material applications such as furniture and chairs, and fashion applications such as bags and shoes. Leather-like sheet-shaped articles are generally produced by applying a polymeric elastomer to a nonwoven fabric made of ultrafine fibers. A leather-like sheet-shaped article in which a knitted fabric or a woven fabric is used as its fibrous substrate, and a resin is applied thereto, has been known (see PTLs 1 and 2).

PTL 3 discloses an artificial leather including a polymeric elastomer applied to a fiber entangled body composed of ultrafine fibers and a woven fabric three-dimensionally intertangled together, the artificial leather having naps with a nap length of 200 to 600 μm and having a density of 0.50 to 0.85 g/cm. Then, according to the disclosure, as a result, an artificial leather having an upscale surface appearance with a dense construction, which also is excellent in mechanical properties and dimensional stability, is provided.

In the artificial leather of PTL 3, the short-fiber-length ultrafine fibers constituting the fiber entangled body are fixed with the polymeric elastomer that serves as a binder. It has been found that there are thus problems in that fluff loss occurs due to wear, or the surface conformability is inferior.

Meanwhile, in the case where a woven or knitted fabric is used as the fibrous substrate in order to solve the above problems, there are problems in that compared to a fiber entangled body or a nonwoven fabric, the denseness of naps is insufficient, or the structure line of the woven or knitted fabric appears on the surface, leading to a slightly inferior surface appearance.

The invention has been accomplished in light of this situation, and an objective thereof is to provide, using a woven fabric or a knitted fabric as a fibrous substrate, a napped leather-like sheet-shaped article that has a good surface appearance and is excellent in fluff loss resistance and surface conformability.

The invention includes the following embodiments.

Here, “structure point” refers to a point where yarns constituting the fibrous substrate cross or entangle with one another. That is, in the case where the fibrous substrate is a woven fabric, a structure point means a point where the warp and weft cross each other. In addition, in the case where the fibrous substrate is a knitted fabric, a structure point means a stitch where a sinker loop and a needle loop are entangled, and the structure points are calculated by counting each stitch as one point.

According to some embodiments of the invention, it is possible to provide, using a woven fabric or a knitted fabric as a fibrous substrate, a napped leather-like sheet-shaped article that has a good surface appearance and is excellent in fluff loss resistance and surface conformability.

A napped leather-like sheet-shaped article according to this embodiment (hereinafter also referred to simply as “sheet-shaped article”) is a napped leather-like sheet-shaped article including a fibrous substrate which is a woven fabric or a knitted fabric, and a resin applied to the fibrous substrate. The sheet-shaped article includes, on a front surface thereof, a napped surface having naps formed from fibers constituting the fibrous substrate, the naps having the resin adhering thereto. “Front surface” of a sheet-shaped article refers to, of the front and back of the sheet-shaped article, the surface that is visible when in use (design surface).

is a cross-sectional view schematically showing a napped leather-like sheet-shaped articleaccording to one example. The sheet-shaped articleincludes a fibrous substrate, which is a woven fabric or a knitted fabric. In this example, the fibrous substratehas a non-illustrated resin applied over its entirety. On a front surfaceof the sheet-shaped article, napsmade of a fiber constituting the woven fabric or the knitted fabric, which serves as the fibrous substrate, are provided. The napshave a resin adhering to the fiber surfaces thereof. The front surfaceof the sheet-shaped articlehas formed thereon a napped surfacehaving the resin-adhering naps. The sheet-shaped articlehas no nap formed on a back surfacethereof.

In this embodiment, the fibrous substrate is a woven fabric or a knitted fabric. Therefore, compared to the case of using a nonwoven fabric, fluff loss due to wear can be suppressed, and surface conformability can also be improved. In one embodiment, it is preferable that the fibrous substrate is composed only of a woven fabric or a knitted fabric.

Surface conformability refers to the ease of conforming to the shape of a surface when a sheet-shaped article is used as a skin material and attached to the surface of an object. Specifically, this means that when a sheet-shaped article is tensioned and attached to a seat, the sheet-shaped article moderately stretches under tension, and that after the attachment, wrinkling caused by the stretch due to tension not being sufficiently reversed can prevented. Therefore, a sheet-shaped article excellent in surface conformability is less likely to wrinkle when attached to the surface of an object.

Woven fabrics include, for example, plain weave, twill weave, and satin weave. Among them, satin weave is preferable, and examples thereof include 5-harness satin, 6-harness satin, 7-harness satin, 8-harness satin, and 12-harness satin. The woven fabric may be a single-ply woven fabric or a multi-ply woven fabric, and is preferably a single-ply woven fabric, a double-ply woven fabric using the face yarn and the back yarn as the warp, or a triple-ply woven fabric using the face yarn, the middle yarn, and the back yarn as the warp. In the case where the fibrous substrate is a woven fabric, it is preferable to use a satin-weave multi-ply woven fabric, and it is more preferable to use a 5-harness satin or 7-harness satin double-ply woven fabric.

The fibrous substrate is preferably a knitted fabric. From the viewpoint of surface conformability, the fibrous substrate is more preferably a weft knitting, and still more preferably a circular knitting. Further, a knit structure in which the connecting yarn forms needle loops and is interlaced with the face yarn and the back yarn is preferable. As such a knit structure, interlock knitting can be mentioned. Favorable examples of interlock knitting include a brush structure and a mockrody structure. Such a knit structure leads to an increase in the yarn fill rate in needle loops, making the needle loops resistance to deformation. Therefore, the improving effects on fatigue durability and fatigue strength can be enhanced. In addition, an increase in the constant load set rate is suppressed, and the improving effect on surface conformability can be enhanced.

The fibrous substrate may be colored with a dye or a pigment, or may also be uncolored.

Fiber materials for constituting the fibrous substrate are not particularly limited, and conventionally known natural fibers, regenerated fibers, semi-synthetic fibers, synthetic fibers, and the like can be used. They can be used alone, and it is also possible to use a combination of two or more kinds. Among them, from the viewpoint of durability, particularly of mechanical strength, heat resistance, and light resistance, the fiber material is preferably a synthetic fiber, more preferably a polyester fiber, and particularly preferably a polyethylene terephthalate fiber.

As the fibrous substrate, one having naps on its surface, that is, a fibrous substrate having a napped surface, is used. The fibrous substrate has naps formed on at least one surface thereof. It is preferable that naps are formed only on one surface of the fibrous substrate. The naps are formed from fibers constituting the woven fabric or the knitted fabric, and are bound by the weave structure or knit structure. Therefore, the improving effects on fluff loss resistance, wear resistance, and the surface conformability can be enhanced. Naps are hairs (fluff) on the surface of a fibrous substrate, and is also referred to as hairy. Naps can be formed, for example, by opening a knit or weave structure or by a raising treatment.

A fineness of fibers constituting the naps (single-fiber fineness) is not particularly limited, but is preferably 0.1 to 0.5 dtex, and more preferably 0.1 to 0.4 dtex. The single-fiber fineness of 0.1 dtex or more leads to good wear resistance. The single-fiber fineness of 0.5 dtex or less is advantageous in improving surface appearance and tactile sensation.

A fineness of yarns constituting the fibrous substrate (yarn fineness) is not particularly limited, but is preferably 50 to 250 dtex, and more preferably 50 to 200 dtex. As a result of the yarn fineness being 50 dtex or more, the improving effects on wear resistance, fluff loss resistance, fatigue durability, and fatigue strength can be enhanced. As a result of the yarn fineness being 250 dtex or less, the improving effects on surface appearance and texture can be enhanced.

A thickness of the fibrous substrate is not particularly limited and may be, for example, 600 to 1,500 μm. More specifically, in the case where the fibrous substrate is a woven fabric, the thickness of the fibrous substrate is preferably 600 to 1,500 μm, and more preferably 800 to 1,200 μm. In the case where the fibrous substrate is a knitted fabric, the thickness of the fibrous substrate is preferably 600 to 1,400 μm, more preferably 600 to 1,300 m, and still more preferably 800 to 1,200 μm. As a result of the thickness of the fibrous substrate being not less than the lower limit, the improving effects on wear resistance, fluff loss resistance, fatigue durability, and fatigue strength can be enhanced. As a result of the thickness of the fibrous substrate being not more than the upper limit, the improving effect on texture can be improved.

The thickness of the fibrous substrate is a value measured in accordance with JIS L 1096:2010 8.4 Method A (JIS method) using a constant pressure thickness gauge (e.g., manufactured by Ozaki Mfg. Co., Ltd.: PEACOCK Dial Gauge H-30), and is a thickness measured including the napped portion.

Incidentally, the single-fiber fineness, the yarn fineness, and the thickness of the fibrous substrate described above are the single-fiber fineness, the yarn fineness, and the thickness regarding the fibrous substrate before the application of a resin. It is also possible that in a napped leather-like sheet-shaped article after resin application, the single-fiber fineness, the yarn fineness, and the thickness of the fibrous substrate (i.e., the thickness of the napped leather-like sheet-shaped article) are set within such ranges.

The resin applied to the fibrous substrate adheres to the surface of fibers constituting the fibrous substrate. As a result of applying a resin to the fibrous substrate, smoothness can be imparted to the front surface of the napped leather-like sheet-shaped article, providing the sheet-shaped article with a good texture.

In order to impart a good texture and wear resistance, the resin is present at least on the front surface side where naps are present in the thickness direction of the fibrous substrate (i.e., the napped surface side). The resin may also be present over the entire thickness of the fibrous substrate. In this case, the resin does not cover the entire napped surface of the fibrous substrate like a film (i.e., not like grain leather), but is applied to the fibrous substrate while reserving the naps. As a result, a napped leather-like sheet-shaped article having a suede-like or nubuck-like appearance and tactile sensation can be obtained.

As resins to be applied to the fibrous substrate, for example, a silicone resin, a polyurethane resin, a polyester resin, an acrylic resin, and the like can be mentioned. They can be used alone, and it is also possible to use a combination of two or more kinds as a mixture. Among them, it is preferable to use a silicone resin from the viewpoint of texture or a polyurethane resin from the viewpoint of wear resistance, and it is more preferable to use a mixture of them. As a result of using a silicone resin to impart smoothness to the front surface of the sheet-shaped article, a good texture is achieved, and, in addition, the load on structure points due to wear can be reduced. In addition, use of a polyurethane resin can prevent the silicone resin from coming off during the production process, allowing the silicone resin to sufficiently exhibit its effects described above.

Silicone resins are not particularly limited, and, for example, a methyl hydrogen silicone resin, an amino-modified silicone resin, a (meth)acrylic-modified silicone resin, and the like can be mentioned. They can be used alone, and it is also possible to use a combination of two or more kinds. Among them, from the viewpoint of wear resistance and texture, a methyl hydrogen silicone resin is preferable. Here, a (meth)acrylic-modified silicone resin means an acrylic-modified silicone resin and/or a methacrylic-modified silicone resin.

As polyurethane resins, for example, a polyether-based polyurethane resin, a polyester-based polyurethane resin, a polycarbonate-based polyurethane resin, and the like can be mentioned. They can be used alone, and it is also possible to use a combination of two or more kinds. Among them, from the viewpoint of wear resistance, a polycarbonate-based polyurethane resin is preferable.

A mass ratio between the silicone resin and the polyurethane resin applied to the fibrous substrate (in terms of solid content) is not particularly limited and may be, for example, silicone resin:polyurethane resin=1:2 to 1:52, or 1:2 to 1:40.

Without interfering with the effects of the invention, the resin may have added thereto various additives such as catalysts, delustering agents, lubricating agents (e.g., silicone oil), surfactants, fillers, leveling agents, thickening agents, crosslinking agents, and penetrating agents.

An amount of resin adhering to the fibrous substrate is not particularly limited. In one embodiment, the amount of resin adhering to the fibrous substrate is, in terms of solid content, preferably 10 g/mor more from the viewpoint of wear resistance and fluff loss resistance and, in addition, preferably 40 g/mor less from the viewpoint of texture. The adhesion amount is more preferably 15 to 25 g/min terms of solid content. Here, the resin adhesion amount does not include the amount of the above additives. In addition, the resin adhesion amount does not include the amount of resin contained in the below-described backing. That is, the above resin applied to at least the front surface side where naps are present in the thickness direction of the fibrous substrate is considered as a first resin and distinguished from a binder resin contained in the backing, which is applied only to the back surface of the sheet-shaped article (second resin). Therefore, the resin adhesion amount is the adhesion amount of the first resin to the fibrous substrate.

A fill rate of the resin (first resin) to the fibrous substrate is not particularly limited. In one embodiment, the fill rate of the resin to the fibrous substrate is preferably 0.5 to 2.8% in the napped part, more preferably 0.5 to 2.5%, and is preferably 3 to 9% in the ground structure part. Within a range not less than the lower limit, the improving effects on wear resistance and fluff loss resistance can be enhanced. Within a range not more than the upper limit, a good texture is likely to be obtained. Here, the resin fill rate is the proportion of resin cross-sections per area in a cross-section of the napped part or the ground structure part of the sheet-shaped article. The napped part refers to the area where naps are present in the thickness direction of the sheet-shaped article. The ground structure part refers to the body part of the fibrous substrate, which is located below the napped part and constitutes the weave structure or the knit structure.

A density of the fibrous substrate is not limited. In the case where the fibrous substrate is a woven fabric, the density of the fibrous substrate is preferably such that it has a warp density of 200 to 500 yarns/25.4 mm and a weft density of 50 to 150 yarns/25.4 mm, more preferably a warp density of 250 to 400 yarns/25.4 mm and a weft density of 50 to 100 yarns/25.4 mm. In the case where the fibrous substrate is a knitted fabric, the density of the fibrous substrate is preferably such that it has 40 to 110 courses/25.4 mm and 30 to 70 wales/25.4 mm, more preferably 60 to 90 courses/25.4 mm and 30 to 50 wales/25.4 mm. As a result of the density of the fibrous substrate being not less than the lower limit, an excellent surface appearance where the structure line of the woven fabric or the knitted fabric is not visible is likely to be obtained. In addition, this is advantageous in improving tactile sensation, wear resistance, fluff loss resistance, fatigue durability, and fatigue strength. As a result of the density of the fibrous substrate being not more than the upper limit, a good texture is likely to be obtained. Incidentally, the density regarding the fibrous substrate described above is the density in a napped leather-like sheet-shaped article with a resin applied thereto. It is also possible that the density before the application of a resin is set within the same ranges as above.

In this embodiment, a number of structure points of yarns constituting the fibrous substrate per unit area of the sheet-shaped article is set as follows. That is, in the case where the fibrous substrate is a woven fabric, the number of structure points per 24.5 mm square of the sheet-shaped article is 1,500 to 10,000, preferably 1,800 to 7,000, and more preferably 2,000 to 4,500, and may also be 3,000 to 7,000. In addition, in the case where the fibrous substrate is a knitted fabric, the number of structure points per 24.5 mm square of the sheet-shaped article is 3,000 to 9,000, preferably 3,500 to 9,000, more preferably 3,500 to 7,700, still more preferably 4,000 to 6,000, and particularly preferably 4,500 to 5,500, and may also be 3,500 to 5,500. As a result of the structure points being not less than the lower limit, the fibrous substrate has an increased density. Accordingly, an excellent surface appearance, where the structure line of the woven fabric or the knitted fabric is not visible, and good tactile sensation are achieved, and the resulting wear resistance, fluff loss resistance, fatigue durability, fatigue strength, and surface conformability are also excellent. As a result of the structure points being not more than the upper limit, a good texture is achieved. Incidentally, the number of structure points described above is the number of structure points in a napped leather-like sheet-shaped article with a resin applied thereto. It is also possible that the number of structure points before the application of a resin is set within the same ranges as above.

As used herein, “per 24.5 mm square of a sheet-shaped article” refers to per square area measuring 25.4 mm in the warp direction and 25.4 mm in the weft direction (25.4×25.4 mm) of the sheet-shaped article. The warp direction and the weft direction of a sheet-shaped article refer to, in a woven fabric, the directions in which the warp and weft run, respectively. In a knitted fabric, the terms refer to the length direction and the width direction at the time of knitting, respectively.

In the case where the fibrous substrate is a woven fabric, a structure point is the point where the warp and weft cross each other as described above. For example, in the complete weave of a 7-harness satin double-ply woven fabric shown in, structure points are points shown in white in the warp row marked “face” (face yarn) and also points shown in black in the warp row marked “back” (back yarn).

In the case of a woven fabric, the number of structure points per 24.5 mm square is calculated by the following formula (1).

In the formula, n represents the number of structures of an n-ply weave structure, and is an integer of 1 to 3, for example. The integer n=1 in the case of a single-ply woven fabric, n=2 in the case of a double-ply woven fabric, and n=3 in the case of a triple-ply woven fabric.

Arepresents the warp density (yarns/25.4 mm) of the kwarp. In particular, in the case of a single-ply woven fabric, Adirectly represents the warp density of the woven fabric. In the case of a double-ply woven fabric, the kwarp represents the face yarn or the back yarn; Arepresents the warp density of the face yarn (first warp), and Arepresents the warp density of the back yarn (second warp). In the case of a triple-ply woven fabric, the kwarp represents the face yarn, the middle yarn, or the back yarn; Arepresents the warp density of the face yarn (first warp), Arepresents the warp density of the middle yarn (second warp), and Arepresents the warp density of the back yarn (third warp).

Brepresents the number of crossings with the weft per kwarp yarn in the weft repeating unit (crossings/yarn) and can be determined from the structure diagram of the weave structure. Here, the weft repeating unit refers to the number of weft yarns forming a complete weave and can be determined from the structure diagram of the weave structure. For example, in the case of the structure diagram shown in, the weft repeating unit is 14 yarns, and Band Bare each 2 crossings/yarn.

C represents the weft density (yarns/25.4 mm). D represents the weft repeating unit (yarns).

In the case where the fibrous substrate is a knitted fabric, a structure point means a stitch where a sinker loop and a needle loop are entangled as described above. That is, in, the portion encircled by a dotted line is a stitch where a sinker loop and a needle loop are entangled (structure point), and the structure points are calculated by counting each stitch as one point.

In the case of a knitted fabric, the calculation formula for structure points differs depending on the knit structure. Therefore, the calculation formula for structure points may be derived from each structure diagram, and the number of structure points is calculated from the obtained calculation formula. For example, in the case of interlock knitting, the number of structure points per 24.5 mm square is calculated by the following formula (2).

In the formula, Grepresents the course density on the front surface (courses/25.4 mm). Hrepresents the existence probability of structure points in the warp direction (length direction) on the front surface. Irepresents the wale density on the front surface (wales/25.4 mm). Jrepresents the existence probability of structure points in the weft direction (width direction) on the front surface. Grepresents the course density (courses/25.4 mm) on the back surface. Hrepresents the existence probability of structure points in the warp direction on the back surface. Irepresents the wale density (wales/25.4 mm) on the back surface. Jrepresents the existence probability of structure points in the weft direction on the back surface.

For example, in the case of a brush structure, the structure diagram is represented by, and the simplified knitted construction as seen from the front surface is as shown in. In this case, with respect to the existence probability Hof structure points in the warp direction on the front surface, as shown in, in the warp direction, out of the three courses, structure points are present for three courses, that is, structure points are present for Gout of G, and thus H=G/G. Similarly, the existence probability Hof Structure points in the warp direction on the back surface is also H=G/G. With respect to the existence probability Jof structure points in the weft direction on the front surface, as shown in, in the weft direction, out of the three wales, structure points are present for three wales, that is, structure points are present for Iout of I, and thus J=I/I. Similarly, the existence probability Jof structure points in the weft direction on the back surface is also J=I/I. Therefore, in the case of a brush structure, the number of structure points is represented by the following formula (2-1).

In the case of a mockrody structure, the structure diagram is represented by. According to the structure diagram, on the front surface, the face yarn and the connecting yarn alternately form courses or wales. In addition, on the back surface, the back yarn and the connecting yarn alternately form courses or wales. According to the structure diagram, the existence probabilities H, J, H, and Jare the same as in the case of a brush structure, that is, H=G/G, J=I/I, H=G/G, and J=I/I. Therefore, the number of structure points in the case of a mockrody structure is represented by the above formula (2-1).