Laminate and synthetic leather

Abstract

Provided is a laminate having: a surface treatment layer; a resin layer containing plant-derived fibers; and a resin layer containing a colorant. In the laminate, bubbles are not generated during a heated bubble generation test. In an image of the laminate, the number average major diameter of the plant-derived fibers is 0.3 to 1.0 mm, the number average minor diameter of the plant-derived fibers is 0.1 to 0.3 mm, and the number average aspect ratio (major diameter / minor diameter) of the plant-derived fibers is 1.5 to 10.

Description

Laminates and synthetic leather

[0001] The present invention relates to a laminate and synthetic leather.

[0002] Studies are underway to partially replace petroleum-derived products with plant-derived materials. Various studies are also being conducted in the field of synthetic leather, as described below. Patent Document 1 discloses a method for producing a formulation based on polyurethane and prickly pear mucilage for use in producing synthetic skin-like flexible coatings. Patent Document 2 discloses a composition for producing a laminate made of cellulose-containing plant material derived from apple waste, a method for producing a laminate from cellulose-containing plant material derived from apple waste, and a laminate produced by the method.

[0003] Patent Document 3 discloses artificial leather having a PVC layer containing coconut shell powder modified vermiculite powder. Patent Document 4 discloses the use of coconut fiber in combination with a rubbery binder for the production of vehicle seat cushions, mattresses, filters, or packaging materials.

[0004] However, none of these documents describe synthetic leather that can be used in applications requiring strength and durability, such as vehicle seats.

[0005] Furthermore, although products that use the technologies described in Patent Document 1 and Patent Document 2 are touted as sustainable products, users are unable to sense the presence of plant-derived materials.

[0006] There is a strong demand for synthetic leather that has a high level of design, allows the wearer to feel the presence of plant-derived materials, and at the same time, is strong and durable.

[0007] Patent Publication No. 2022-544741 US Patent Application Publication No. 2021 / 0189642 Chinese Patent Application Publication No. 112721364 International Publication No. 97 / 005313

[0008] The present invention aims to solve the above-mentioned problems of the prior art and achieve the following objective: to provide synthetic leather that has high design quality, allows the user to feel the presence of plant-derived materials, and at the same time, has strength and durability.

[0009] As a result of intensive research to achieve the above object, the inventors have discovered that a laminate having a surface treatment layer, a resin layer containing plant-derived fibers, and a resin layer containing a colorant, wherein the laminate does not generate bubbles in a heat bubble generation test, and wherein, in an image of the laminate, the plant-derived fibers have a number-average major axis of 0.3 mm to 1.0 mm, a number-average minor axis of 0.1 mm to 0.3 mm, and a number-average aspect ratio (major axis / minor axis) of the plant-derived fibers is 1.5 to 10, can provide a laminate and synthetic leather with a high level of design quality that allows the presence of plant-derived materials to be felt while at the same time providing strength and durability. Here, "a level of design quality" refers to a level that evokes an aesthetic sense and allows for a variety of design variations to be achieved by changing the color, dispersion state, etc. The number-average aspect ratio, number-average major axis, and number-average minor axis of the plant-derived fibers are values ​​measured from images of the laminate or synthetic leather.

[0010] The present invention is based on the above-mentioned findings of the present inventors, and provides the following means for solving the above problems: Namely, <1> A laminate having a surface treatment layer, a resin layer containing plant-derived fibers, and a resin layer containing a colorant, wherein the laminate does not generate bubbles in a heat bubble generation test, and an image of the laminate shows that the plant-derived fibers have a number average major axis of 0.3 mm or more and 1.0 mm or less, a number average minor axis of 0.1 mm or more and 0.3 mm or less, and a number average aspect ratio (major axis / minor axis) of the plant-derived fibers is 1.5 or more and 10 or less. <2> A method for producing a laminate, comprising: a pellet production step of stirring polyvinyl chloride (PVC), 50 parts by mass or more and 200 parts by mass or less of a plasticizer per 100 parts by mass of the polyvinyl chloride (PVC), and dried plant-derived fibers, and producing pellets using an extruder; a plant-derived fiber-containing resin layer formation step of forming a resin layer containing the plant-derived fibers from the pellets; and a laminate formation step of forming a laminate having a surface-treated layer, a resin layer containing the plant-derived fibers, and a resin layer containing a colorant.

[0011] According to the present invention, the above-mentioned problems of the prior art can be solved, the above-mentioned object can be achieved, and a synthetic leather can be provided which has a high level of design, allows the user to feel the presence of plant-derived materials, and at the same time has strength and durability.

[0012] FIG. 1 is a schematic diagram showing the layer structure of a laminate. FIG. 2 is a photograph of the laminate of Example 1. FIG. 3 is a diagram showing the results of a moisture absorption test of coconut-derived fibers. FIG. 4 is a photograph of an example in which no bubbles were generated in a heat bubble generation test. FIG. 5 is a photograph of an example in which a large number of bubbles were generated over the entire surface in a heat bubble generation test. FIG. 6 is a diagram showing the apparatus used in the constant-load low-temperature bending test. FIG. 7 is an image (part 1) obtained by processing using image processing analysis software. FIG. 8 is an image (part 2) obtained by processing using image processing analysis software. FIG. 9 is an image (part 3) obtained by processing using image processing analysis software. FIG. 10 is a schematic diagram of a resin layer containing plant-derived fibers for explaining the degree of envelopment. FIG. 11 is a photograph of a resin layer containing plant-derived fibers for explaining the degree of envelopment.

[0013] (Laminate) The laminate has a resin layer containing a colorant, a resin layer containing plant-derived fibers, a surface-treated layer, and may further have other layers. The laminate can be used for various purposes, and can also be used as synthetic leather containing plant-derived fibers.

[0014] In the laminate, a resin layer containing the plant-derived fiber can be provided on the resin layer containing the colorant, and the surface treatment layer can be provided on the opposite side of the resin layer containing the plant-derived fiber to the resin layer containing the colorant. The resin layer containing the plant-derived fiber and the surface treatment layer can be in direct contact with each other, or the other layer can be provided between the resin layer containing the plant-derived fiber and the surface treatment layer.

[0015] <Resin Layer Containing Colorant> The resin layer containing a colorant may contain a colorant, a resin, a plasticizer, a filler, and other components.

[0016] The resin layer containing the colorant can be produced by melt-kneading the above components and rolling them.

[0017] <<Colorant>> The colorant is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include pigments and dyes. These may be used alone or in combination of two or more. Among these, pigments are preferred in terms of coloring power and hiding power.

[0018] The pigment is not particularly limited and can be appropriately selected depending on the purpose, and may be an inorganic pigment or an organic pigment. These may be used alone or in combination of two or more kinds.

[0019] The inorganic pigment is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include carbon black, titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, chrome yellow, etc. The organic pigment is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include azo pigments, polycyclic pigments (e.g., phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, quinophthalone pigments, etc.), dye chelates (e.g., basic dye chelates, acid dye chelates, etc.), nitro pigments, nitroso pigments, aniline black, etc.

[0020] The content of the colorant in the resin layer containing the colorant is not particularly limited and can be selected appropriately depending on the purpose. However, from the viewpoint of producing a laminate and synthetic leather that has a high design quality and allows the presence of plant-derived materials to be clearly felt, the content is preferably 0.1% by mass or more and 30% by mass or less, and more preferably 0.5% by mass or more and 10% by mass or less.

[0021] The color of the colorant is not particularly limited and can be appropriately selected depending on the purpose, but black, white, brown, yellow, red, blue, green, or purple is preferred. An example of the black colorant is carbon black. An example of the white colorant is Pigment White 6. An example of the brown colorant is Pigment Red 101. An example of the yellow colorant is Pigment Brown 24 or Pigment Yellow 181. An example of the red colorant is Pigment Red 221 or Pigment Red 254. An example of the blue colorant is Pigment Blue 15. An example of the green colorant is Pigment Green 7. An example of the purple colorant is Pigment Violet 23. The above can also be mixed to produce grays and beiges.

[0022] <<Resin>> The resin is not particularly limited and can be appropriately selected depending on the purpose. Examples include polyvinyl chloride (PVC) (vinyl chloride resin), urethane resin, polyester resin, acrylic resin, vinyl acetate resin, styrene resin, butadiene resin, styrene-butadiene resin, acrylic-styrene resin, and acrylic-silicone resin. These may be used alone or in combination of two or more. Among these, polyvinyl chloride (PVC) (vinyl chloride resin) is preferred because it is durable and can be easily decorated in various ways.

[0023] The polyvinyl chloride (PVC) can be produced by a polymerization reaction of vinyl chloride (chloroethylene). Commercially available polyvinyl chloride (PVC) can also be used. The polymerization reaction is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include a suspension polymerization method and an emulsion polymerization method (paste polymerization method).

[0024] The properties of the polyvinyl chloride (PVC) are not particularly limited and can be appropriately selected depending on the purpose, but it is preferable that the polyvinyl chloride (PVC) has an average degree of polymerization of 800 or more and 2500 or less. The polyvinyl chloride (PVC) may be modified polyvinyl chloride (PVC).

[0025] Examples of commercially available polyvinyl chloride (PVC) products include the TE series and TH series manufactured by Taiyo Vinyl Chloride Co., Ltd., the TK series manufactured by Shin-Etsu Chemical Co., Ltd., and the PSH series and PSM series manufactured by Kaneka Corporation.

[0026] <<Plasticizer>> The plasticizer is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include phthalate esters such as dialkyl phthalate, adipic acid esters, trimellitic acid esters, etc. These may be used alone or in combination of two or more.

[0027] The content of the plasticizer relative to the resin in the resin layer containing the colorant is not particularly limited and can be selected appropriately depending on the purpose. From the viewpoint of producing synthetic leather that has strength and durability, however, the content is preferably 50% by mass or more and 150% by mass or less, and more preferably 80% by mass or more and 120% by mass or less.

[0028] <<Filler>> The filler is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include alumina, titanium dioxide, zinc oxide, cerium dioxide, calcium carbonate, silica, talc, magnesium hydroxide, mica, barium sulfate, silicic acid, ammonium polyphosphate, aluminum dialkylphosphinate, poly(melamine phosphate), carbon black, carbon nanotubes, carbon fiber, etc. These may be used alone or in combination of two or more.

[0029] The content of the filler relative to the resin in the resin layer containing the colorant is not particularly limited and can be selected appropriately depending on the purpose. However, from the viewpoint of producing synthetic leather that has strength and durability, the content is preferably 3% by mass or more and 20% by mass or less, and more preferably 5% by mass or more and 10% by mass or less.

[0030] <<Other Components>> The other components are not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include stabilizers.

[0031] The thickness of the resin layer containing the colorant is not particularly limited and can be appropriately selected depending on the purpose. From the viewpoint of strength and durability, the thickness is preferably 20 μm or more and 1000 μm or less, more preferably 100 μm or more and 500 μm or less, even more preferably 150 μm or more and 350 μm or less, and particularly preferably 200 μm or more and 300 μm or less.

[0032] <Resin Layer Containing Plant-Derived Fibers> The resin layer containing plant-derived fibers may contain plant-derived fibers, resin, plasticizer, filler, and other components. The resin layer containing plant-derived fibers may also contain a colorant. The colorant content is 0% by mass or more and 5% by mass or less, preferably 0% by mass or more and 3% by mass or less. Coloring the resin layer containing plant-derived fibers may prevent the plant-derived fibers from being unnecessarily conspicuous, leading to a more natural impression. At the same time, this also has the effect of increasing the coloring power and hiding power of the entire laminate. The colorant is as described above in <Resin Layer Containing Colorant>.

[0033] The resin, plasticizer, filler, and other components are as described above in <Resin layer containing colorant>.

[0034] The resin layer containing the plant-derived fibers can be produced by pelletizing the plant-derived fibers immediately after drying, dispersing them in a base resin, and rolling them.

[0035] <Pellet> To prevent re-adsorption of moisture and deterioration during transportation, it is preferable to dry the plant-derived fibers and, immediately after drying, melt-knead the plant-derived fibers and the resin and other material powders to form pellets. The pelletization is carried out using a twin-screw extruder after mixing the material powders. The plant-derived fiber content in the pellets is not particularly limited and can be selected appropriately depending on the purpose, but is preferably 30% to 60% by mass. During pellet preparation, plasticizers, stabilizers, lubricants, and gelation accelerators may be added as needed. The gelation accelerators create a pseudo-crosslinked state with resin molecules, imparting melt elasticity. Acrylic polymers are used as gelation accelerators for polyvinyl chloride (PVC).

[0036] The pellets are not particularly limited and can be appropriately selected depending on the purpose, but pellets produced using an extruder are preferred, in which dried plant-derived fibers are immersed in a plasticizer (liquid) immediately after drying, and stirred while adding powder of a resin such as polyvinyl chloride (PVC).

[0037] The amount of plasticizer per 100 parts by mass of the resin is not particularly limited and can be selected appropriately depending on the purpose. However, from the viewpoint of preventing the plant-derived fibers from being pulverized during pellet formation and from the viewpoint of ensuring uniform dispersion of the plant-derived fibers without bias when the pellets are dispersed in the base resin, the amount is preferably 50 parts by mass or more and 200 parts by mass or less, and more preferably 80 parts by mass or more and 160 parts by mass or less.

[0038] <<Plant-derived fibers>> The plant-derived fibers are not particularly limited and can be appropriately selected from fibers made from plant materials depending on the purpose. These fibers may be used alone or in combination of two or more.

[0039] Although not necessarily an essential or academic classification, plants can be broadly divided into woody and herbaceous plants as follows: Woody: a group of plants that grow by accumulating xylem cells year after year Herbaceous: a group of plants that do not have xylem and die within one to several years Whether woody or herbaceous, any fibrous material that satisfies the aspect ratio, major axis, and minor axis ranges of the present invention can be used, but for reasons such as ease of procurement and processing, the fact that it is not an edible part, and the difficulty of using it for other purposes such as fuel, fibrous materials from the leaves, stems, and petals of herbaceous plants and non-woody leaves, fruits, petals, etc. of woody plants are preferred.

[0040] Specifically, examples of herbaceous plants include leaves of grasses, rice, wheat, barley, rye, etc., rice husks after threshing, corn leaves, husks, and beards (pistils), petals of ornamental plants, and evergreen perennials such as Erianthus and Miscanthus. Examples of fibrous materials such as non-woody leaves, fruits, and petals of woody plants include pine needles, cherry blossoms and leaves, fruit skins (coffee bean husks, apple, mandarin orange, banana peel, peanut shells and husks, walnut shells), bamboo leaves, bamboo leaves, and coconuts. Among these, coconut-derived fibers are particularly preferred, and coconut fiber is more preferred, as they are difficult to use for other purposes and are discarded in large quantities, and are said to generate greenhouse gases such as methane gas when decomposed.

[0041] The palm-derived fiber is a fiber derived from a plant belonging to the Arecaceae family. The plant belonging to the Arecaceae family is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include plants belonging to the subfamily Arecaceae, Acetoplastideae, Apoideae, Apoideae, and Apoideae. Among these, plants belonging to the Arecaceae subfamily are preferred from the viewpoint of producing a laminate in which the presence of plant-derived materials can be felt.

[0042] Plants belonging to the Areca subfamily are not particularly limited and can be appropriately selected depending on the purpose, and examples include plants belonging to the tribes Areca, Cocos, Euterpe, Geonom, Iriartea, Leoportiniae, Orania, Pelagodoxae, Podococcus, Reinhardtia, Leustonea, and Sclerosperma. Among these, plants belonging to the tribe Cocos are preferred in terms of producing a laminate that allows the presence of plant-derived materials to be felt.

[0043] The plant belonging to the Coconut family is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include coconut palm of the genus Coconut, oil palm of the genus Oil palm, Bactris chontaduro, etc. Among these, coconut palm of the genus Coconut is preferred from the viewpoint of producing a laminate in which the presence of plant-derived materials can be clearly felt.

[0044] There are no particular restrictions on the part of the plant belonging to the palm family, and it can be selected appropriately depending on the purpose, but from the viewpoint of producing a laminate that allows the presence of plant-derived materials to be felt, the fruit is preferred, and the fruit's outer skin (coconut fiber) is more preferred.

[0045] The method for producing the plant-derived fibers is not particularly limited and can be appropriately selected depending on the purpose. For example, there is a method in which a fiber raw material (long fiber) having a length of several tens of centimeters is crushed from the outer skin of the fruit of a plant belonging to the palm family (coconut fiber) using a cutter mill (φ2 mm screen), and then the crushed fiber is passed through a mesh with a desired mesh size and then dried.

[0046] The temperature for drying after the grinding is not particularly limited and can be selected appropriately depending on the purpose. However, from the viewpoint of preventing deterioration of the plant-derived fibers, the temperature is preferably 50°C or higher and 100°C or lower, more preferably 50°C or higher and 80°C or lower, and particularly preferably 50°C or higher and 70°C or lower.

[0047] The drying time after the pulverization is not particularly limited and can be appropriately selected depending on the purpose. However, from the viewpoint of producing a laminate in which no moisture remains, the drying time is preferably 2 hours or more and 100 hours or less, and more preferably 10 hours or more and 80 hours or less.

[0048] The moisture content of the plant-derived fiber is preferably 2.0% by mass or less, and particularly preferably 1.5% by mass or less. The moisture content of the plant-derived fiber is measured using an infrared moisture meter, FD-600 (manufactured by Kett Electric Laboratory Co., Ltd.).

[0049] The moisture content of the coconut-derived fiber can be reduced by appropriately adjusting the drying conditions and drying time. However, according to the studies of the present inventors, coconut-derived fiber re-adsorbs moisture at a very rapid rate even in a room temperature environment. Therefore, after drying, the fiber needs to be pelletized in order to control the re-adsorption of moisture until it is introduced into the melt-kneading process.

[0050] <Heating bubble generation test> The laminate preferably does not generate bubbles in a heating bubble generation test. That is, the bubble area ratio, which is a numerical value obtained by quantifying the bubble generation state in the heating bubble generation test, is preferably 0%. If the bubble area ratio, which is a numerical value obtained by quantifying the bubble generation state in the heating bubble generation test, exceeds 0.20%, the durability and strength required for a vehicle seat are not met. Furthermore, even if bubbles are generated on the bonding surface during the heat bonding process, even if they are slight, this significantly impairs the aesthetic appearance of the vehicle seat. For the purpose of preventing bubble generation in the heating bubble generation test, the above-mentioned pellets can be preferably used.

[0051] The state of bubble generation in the heat bubble generation test is confirmed and measured by the following method.

[0052] - Heating bubble expansion step - The laminate test piece is heated at 170°C, 0.5 MPa, and for 5 minutes. If the coconut-derived fiber contains moisture, fine bubbles are generated by heating, and when observed under an optical microscope, the bubbles near the surface of the polyvinyl chloride (PVC) burst and appear as black dots, while the unburied internal bubbles appear as white dots.

[0053] - Image capture conditions - Digital images are acquired using an optical microscope (for example, a Keyence digital microscope). Figure 4 shows an example of a photograph of an example in which no bubbles were generated in the thermal bubble generation test. Figure 5 shows an example of a photograph of an example in which many bubbles were generated over the entire surface in the thermal bubble generation test.

[0054] - Image processing - Using image processing software capable of binarizing images, Mitani Corporation's image analysis software WinROOF2021 Standard, the image was binarized by dividing it into black dots where bubbles had burst and the rest of the image. The binarization process was performed in automatic binarization mode. The binarized image was then colored a different color to confirm that it overlapped with the black dots in the original image. The bubble area ratio (%) was calculated by dividing the total area of ​​the black dots by the total area of ​​the measurement range of the image.

[0055] The above-mentioned heat bubble generation test uses the area value of bubbles that burst and appear as black dots near the surface of the PVC, so the bubble generation state can be identified regardless of the thickness of the resin layer containing plant-derived fibers.

[0056] The plant-derived fiber-containing resin layer of the present invention is a thick, sheet-like layer made of a composite material in which highly hygroscopic fibers are dispersed in a hydrophobic resin. Existing moisture quantification methods, such as thermal analysis and the Karl Fischer method, make it difficult to quantitatively evaluate the moisture content of the resin layer itself, including the moisture held by the plant-derived fibers dispersed therein (i.e., the plant-derived fibers encapsulated in the binder). Therefore, when quantifying the moisture content of the plant-derived fiber-containing resin layer itself, it is necessary to express the bubble generation state in the heat-induced bubble generation test of the present invention using the bubble area ratio, which is quantified by image processing.

[0057] The number-average aspect ratio (major axis / minor axis) of the plant-derived fibers in the image of the laminate is not particularly limited as long as it is 1.5 or more and 10 or less, and can be appropriately selected depending on the purpose, but from the viewpoint of producing a laminate and synthetic leather that highlights the presence of plant-derived materials and creates an aesthetic impression, it is preferably 2 or more and 9 or less, more preferably 2 or more and 8 or less, even more preferably 3 or more and 8 or less, and particularly preferably 3 or more and 5 or less. If the number-average aspect ratio (major axis / minor axis) of the plant-derived fibers exceeds 10, the fibers will overlap and become entangled, creating a foreign-body feel. If the number-average aspect ratio (major axis / minor axis) of the plant-derived fibers is less than 1.5, the appearance of a natural fiber material will be diminished, creating a foreign-body feel.

[0058] The number average major axis of the plant-derived fibers in the image of the laminate is not particularly limited as long as it is 0.3 mm or more and 1.0 mm or less, and can be appropriately selected depending on the purpose. However, from the viewpoint of producing a laminate and synthetic leather that highlights the presence of plant-derived materials and evokes an aesthetic impression, the number average major axis is preferably 0.3 mm or more and 0.9 mm or less, and particularly preferably 0.4 mm or more and 0.8 mm or less.

[0059] In the image of the laminate, it is preferable that the plant-derived fibers do not contain any plant-derived fibers having a major diameter of 1.5 mm or more, and it is more preferable that the plant-derived fibers do not contain any plant-derived fibers having a major diameter of 2.0 mm or more. If the major diameter of the plant-derived fibers exceeds 1.5 mm, the fibers are long and give the impression of being a somewhat foreign body, which detracts from the aesthetic appeal. Furthermore, if the plant-derived fibers contain fibers having a major diameter of more than 2.0 mm, the durability and strength required for a vehicle seat are not met.

[0060] The number-average minor axis (thickness) of the plant-derived fibers in the image of the laminate is not particularly limited as long as it is 0.1 mm or more and 0.3 mm or less, and can be appropriately selected depending on the purpose. Due to the nature of plant-derived fibers, they tend to break along the fiber direction when crushed. Therefore, to obtain plant-derived fibers within the above-mentioned range of major axis, it is preferable to prepare them so that the average minor axis (thickness) is 1.0 mm or less. From the viewpoint of producing a laminate and synthetic leather that allows the presence of plant-derived materials to be felt in a highly design-oriented manner, a number-average minor axis (thickness) of 0.1 mm or more and 0.2 mm or less is particularly preferred. If the number-average minor axis (thickness) is less than 0.1 mm, it gives the impression of the presence of elongated foreign matter, which detracts from the aesthetic appeal.

[0061] In terms of the combination of the number-average aspect ratio, number-average major axis, and number-average minor axis of the plant-derived fibers in the image of the laminate, from the viewpoint of producing a laminate and synthetic leather that highlights the presence of the plant-derived material and evokes an aesthetic impression, a combination in which the number-average major axis is in the range of 0.3 mm to 1.0 mm, the number-average minor axis is in the range of 0.1 mm to 0.3 mm, and the number-average aspect ratio is in the range of 1.5 to 10 is preferred, and a combination in which the number-average major axis is in the range of 0.4 mm to 0.8 mm, the number-average minor axis is in the range of 0.1 mm to 0.2 mm, and the number-average aspect ratio is in the range of 2 to 8 is most preferred.

[0062] The number average major axis and number average minor axis of the plant-derived fibers in the raw material are determined by crushing the plant-derived fibers, passing a sample through a mesh having openings in a desired range, drying the sample, and then examining the sample with an optical microscope.

[0063] The number-average major axis and number-average minor axis of the plant-derived fibers in the image of the laminate were measured by observing the produced laminate with an optical microscope. In both cases, the major axis and minor axis of 300 particles were measured by comparing them with the scale lines in a photograph of the particle image taken at 30x magnification, and the arithmetic mean values ​​of the major axis, minor axis, and aspect ratio of the 300 particles were calculated. In this case, flake-like dust particles with a diameter of less than 0.10 mm and an aspect ratio of less than 1.5 were excluded from the measurement. The major axis was the length of the perpendicular line connecting two parallel lines tangent to the outline of the image of the plant-derived fiber particle, where the distance between the two parallel lines was the greatest. The minor axis was the length connecting the two intersections of a line parallel to the two parallel lines passing through a point halfway between the perpendicular line and the outline of the image of the plant-derived fiber particle.

[0064] As a method for adjusting the number-average major axis and number-average minor axis of the plant-derived fibers, when the particle size is reduced using a fine grinder with a classification mechanism (generally a grinder such as a jet mill aiming for a particle size of 10 μm or less), the number of times of processing in the grinder increases, and the aspect ratio tends to approach 1. However, the plant-derived fibers of the present invention having a number-average aspect ratio of 1.5 to 15, a number-average major axis of 0.2 mm to 3.0 mm, and a number-average minor axis of 0.03 mm to 1.0 mm can be produced by using a cutter mill and adjusting the screen size and the gap between the screen and the rotor, without using a fine grinder such as a jet mill.

[0065] Since fibrous materials easily pass through a screen in the direction of their major diameter, adjusting the clearance between the screen and the rotor to a wider value can produce coarsely pulverized material with a large major diameter. Alternatively, using a screen with a large mesh size can also produce coarsely pulverized material with a large major diameter. Due to the nature of plant-derived fibers, they tend to break along the fiber direction when pulverized, so increasing the number of times they are processed in a cutter mill tends to reduce their minor diameter (thickness). Therefore, even if the major diameter is the same, obtaining fibrous particles with a desired major diameter by a single coarse pulverization process can be achieved by processing in two stages, with the screen-rotor clearance narrowed in stages, resulting in a smaller minor diameter (thickness) in the latter case. This multi-stage process, in which the screen-rotor clearance is gradually changed, can produce fibrous particles with various combinations of major and minor diameters (thickness). A classification step may be provided in which the coarsely pulverized material is classified using a classifier such as an air classifier or an elbow jet to remove fine dust and separate particles by size, and the classification step may be provided between multiple pulverization steps. Since plant-derived fibers have a tendency to break easily along the fiber direction, it is preferable to prepare them so that the average minor diameter (thickness) is 1.0 mm or less; if the minor diameter (thickness) exceeds this range, it may be difficult to obtain fibrous particles with the desired major diameter.

[0066] Furthermore, coarse particles can be removed by passing the fibrous particles after pulverization or classification through a mesh. Since fibrous materials tend to pass through a screen in the long diameter direction, they may contain coarse particles with a large long diameter. However, by adjusting the vibration frequency and amplitude when passing through the mesh, such coarse particles can be removed. In this case, multiple meshes with different mesh openings can also be used. In this manner, fibrous particles with the desired aspect ratio, long diameter, and short diameter can be obtained. Similarly, fibers with a long diameter of 2.0 mm or more can be removed.

[0067] The content of the plant-derived fibers in the resin layer containing the plant-derived fibers is not particularly limited and can be appropriately selected depending on the purpose. However, in order to make the presence of the plant-derived fibers noticeable, to create an aesthetic impression, and to give a natural impression without giving a busy (messy) impression, the content is preferably 0.2% by mass to 10% by mass, more preferably 0.5% by mass to 8.0% by mass, and even more preferably 1.0% by mass to 4.0% by mass.

[0068] The average value of the area ratio of the plant-derived fibers in the image of the resin layer containing the plant-derived fibers (100 × area of ​​the part where the plant-derived fibers are present / total area of ​​the part where the plant-derived fibers are present and other parts) is not particularly limited and can be selected appropriately depending on the purpose, but from the viewpoint of creating an aesthetic impression and giving a natural impression, it is preferably 3.0% or more and 8.0% or less, and more preferably 4.0% or more and 6.0% or less.

[0069] The lower limit of the average value of the envelopment degree of the plant-derived fibers (an index representing the aggregation state of the plant-derived fibers: (convex perimeter (C PERI) (Convex Perimeter: the perimeter when connecting the convex parts of a figure) / (perimeter (PERI) (Perimeter: the perimeter of the figure)) in an image of the resin layer containing the plant-derived fibers is not particularly limited and can be appropriately selected depending on the purpose, but from the viewpoint of creating an aesthetic sense and giving a natural impression, it is preferably 98.0% or more, and more preferably 99.0% or more. The lower limit of the average value of the envelopment degree of the plant-derived fibers (an index representing the aggregation state of the plant-derived fibers: (convex perimeter (C PERI) (Convex Perimeter: the perimeter when connecting the convex parts of a figure) / (perimeter (PERI) (Perimeter: the perimeter of the figure)) in an image of the resin layer containing the plant-derived fibers is not particularly limited and can be appropriately selected depending on the purpose. There is no particular upper limit to the average value of (Perimeter: perimeter when connecting the convex portions of the graphic) / perimeter (PERI) (Perimeter: perimeter of the graphic), and it can be selected appropriately depending on the purpose. However, from the viewpoint of evoking a sense of beauty and giving a natural impression, it is preferably 99.9% or less. Among these, from the viewpoint of evoking a sense of beauty and giving a natural impression, it is preferably 98.0% or more and 99.9% or less. In the image of the resin layer containing the plant-derived fibers, the number ratio of particles having an average envelopment degree of the plant-derived fibers of 90% or less is preferably 3.0% or less, more preferably less than 3.0%, and even more preferably none.

[0070] An image of the resin layer is obtained under the following (image capturing conditions), and the occupied area ratio and envelopment degree of the plant-derived fiber are measured under the following (image processing conditions).

[0071] (Image capture conditions) Digital image acquisition optical microscope: Keyence digital microscope Magnification: 30x magnification when measuring the occupied area ratio, 50x magnification when measuring the envelopment ratio

[0072] (Image processing conditions) Size of processed image: When measuring the occupied area ratio (magnification 30 times), 7.35 mm x 9.80 mm When measuring the envelopment ratio (magnification 50 times), 4.41 mm x 5.88 mm

[0073] The calculation is performed using image processing and analysis software, WinROOF CLOUD, manufactured by Mitani Shoji Co., Ltd., by the following process.

[0074] <Sampling> 1. Monochrome Imaging If the image is a color image, it is converted to a monochrome image. Monochrome imaging can be performed by selecting monochrome imaging processing or RGB (red, green, blue) separation processing from the menu of the image analysis software WinROOF CLOUD manufactured by Mitani Corporation.

[0075] 2. Noise Removal Next, to remove fine noise that cannot be seen with the naked eye, the image is processed in noise removal mode under the condition that noise of 50 μm or less is removed.

[0076] 3. Density Conversion (Binarization) Next, the image density is adjusted by density conversion so that the outline of the area where the plant-derived fiber is present is clearly defined. (1) The area where the plant-derived fiber is present in the original image and (2) the outline of the image after density conversion (the area where the measurement sample (plant-derived fiber) is present is displayed in white on the screen) are visually confirmed to be completely overlapped. If the density conversion results in a lack of complete overlap (for example, if the outline of (2) is larger than that of (1) or if the outline of (1) is larger than that of (2)), the input image density range for density conversion is adjusted so that the area where the plant-derived fiber is present in the original image and the outline of the image after density conversion are completely overlapped.

[0077] 4. Binarization Next, binarization is performed. The areas where plant-derived fibers exist are binarized from the other areas, and complete overlap is confirmed visually between (1) the areas where plant-derived fibers exist in the original image and (2) the outline of the binarized image (the areas where the measurement sample (plant-derived fibers) exist are displayed in green on the screen). If there is no complete overlap in automatic binarization mode (for example, if the outline of (2) is larger than (1) or if the outline of (1) is larger than (2)), the sampling brightness range is adjusted so that the areas where plant-derived fibers exist in the original image and the outline of the binarized image completely overlap.

[0078] Figure 7 shows the original image at 50x magnification after processing using image processing analysis software. Figure 8 shows the image after 1. monochrome imaging, 2. noise removal, and 3. density conversion (binarization) after processing using image processing analysis software. Figure 9 shows the image after 4. binarization after processing using image processing analysis software.

[0079] <Exclusive Area Ratio> Particles are measured from the measurement menu of the image analysis software WinROOF CLOUD manufactured by Mitani Corporation, the data of the sampled particles is transferred to a spreadsheet software, and the total area value of particles having a circle equivalent diameter of 50 μm or more among the sampled particles is calculated and divided by the area of ​​the entire image to calculate the exclusive area ratio. The average value of the exclusive area ratio calculated from 10 images is used.

[0080] <Envelope Ratio> Particles are measured from the measurement menu of the image analysis software WinROOF CLOUD manufactured by Mitani Corporation, and the data of the sampled particles is transferred to a spreadsheet software. The envelope ratio is calculated from the perimeter and envelope perimeter for each of the sampled particles having a circle-equivalent diameter of 100 μm or more. The average value of the envelope ratios calculated from 10 images is used. At this time, sampling numbers are drawn on the images. This operation makes it possible to compare the data of each particle on the image with the data of each sampled particle by sampling number.

[0081] The degree of envelopment is defined by the following formula 1. Here, the denominator and numerator of Equation 1 will be explained.

[0082] <Perimeter (PERI)> The perimeter (PERI) is the perimeter of a graphic.

[0083] <Convex Perimeter (C PERI)> The convex perimeter (C PERI) is the perimeter (convex perimeter) when connecting the convex portions of a shape.

[0084] The degree of envelopment is 100% (maximum value) when all particles are separated, and decreases as the number of overlapping particles increases.

[0085] For example, in the particle group shown in Figure 10, when the particles are separated (the two particles on the left), the perimeter and the envelope perimeter are the same, so the degree of envelopment of each particle is 100%, but when the particles overlap (the two overlapping particles on the right), the envelope perimeter is the length of the dotted line portion, which is smaller than the perimeter, so the degree of envelopment is lower than 100%.

[0086] In the particle shown in Figure 11, which has a circle-equivalent diameter of 401 µm, two fibers are in contact, but the degree of envelopment is 69.5%. When two particles are in contact or overlapping, the perimeter becomes larger than the enveloping perimeter, and the degree of envelopment becomes lower. Particles with such a low degree of envelopment impair the aesthetic appearance and give the impression of a foreign object that is not a natural fiber material.

[0087] To bring the degree of enmeshment closer to 100, i.e., to bring the particles closer to a non-overlapping state, it is preferable to uniformly dilute the plant-derived fiber-containing pellets with the resin melt, and it is preferable to use plasticized pellets containing 50 to 200 parts by weight of a plasticizer per 100 parts by weight of the resin. Generally, when preparing a pellet-shaped masterbatch for the purpose of dispersing a colorant in a hard resin, a plasticizer is not used to impart a strong shear force. However, to obtain the plant-derived fiber-containing laminate of the present invention, in which the average degree of enmeshment (%) of the plant-derived fibers in an image of the resin layer containing the plant-derived fibers is 98.0 to 99.9%, and the number ratio of plant-derived fiber particles having a degree of enmeshment of 90% or less is 5.0% or less, it is preferable to add a plasticizer during pelletization to prepare relatively soft plasticized pellets, which are then uniformly diluted with the resin melt.

[0088] The thickness of the resin layer containing the plant-derived fibers is not particularly limited and can be appropriately selected depending on the purpose. From the viewpoint of strength and durability, the thickness is preferably 20 μm or more and 1000 μm or less, more preferably 100 μm or more and 500 μm or less, even more preferably 150 μm or more and 400 μm or less, and particularly preferably 200 μm or more and 300 μm or less.

[0089] The tensile strength and elongation of the resin layer containing the plant-derived fibers are preferably 90% or more, where the tensile strength and elongation of a reference sample (a polyvinyl chloride (PVC) layer containing no plant-derived fibers) in which no plant fibers are added to PVC is taken as 100%, and more preferably are equivalent to those of a reference sample (a polyvinyl chloride (PVC) layer containing no plant-derived fibers) in which no plant fibers are added to PVC.

[0090] The tensile strength and elongation are measured in accordance with the JIS 6251 dumbbell test. Dumbbell-shaped test pieces are prepared in accordance with JIS K 6250, Section 8 (Collection and preparation of test pieces). The dumbbell test piece is attached to a tensile tester, and the maximum load (tensile strength) and elongation until the test piece breaks are measured. A reference sample (a polyvinyl chloride (PVC) layer containing no plant-derived fibers) is prepared and evaluated without adding plant fibers to the PVC.

[0091] The constant-load, low-temperature bending resistance of the polyvinyl chloride (PVC) layer containing plant-derived fibers is preferably 90% or more of the constant-load, low-temperature bending resistance of a reference sample (a polyvinyl chloride (PVC) layer containing no plant-derived fibers) to which no plant fibers are added, taken as 100%, and is more preferably equivalent to the reference sample (a polyvinyl chloride (PVC) layer containing no plant-derived fibers) to which no plant fibers are added.

[0092] The constant-load low-temperature flex test is performed using the device shown in Figure 6. The test temperature is -20±2°C, the load is 1.96 N, and the number of times until cracks appear in the resin layer is measured. A reference sample (a polyvinyl chloride (PVC) layer containing no plant-derived fibers) is prepared and evaluated, with no plant fibers added to the PVC.

[0093] <Surface Treatment Layer> The surface treatment layer may contain polyurethane.

[0094] The content of the polyurethane in the surface treatment layer is not particularly limited and can be appropriately selected depending on the purpose.

[0095] The thickness of the surface treatment layer is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 5 μm or more and 20 μm or less, and more preferably 10 μm or more and 20 μm or less.

[0096] <Other Layers> The other layers are not particularly limited and may be appropriately selected depending on the purpose. Examples thereof include a base fabric, an adhesive layer, and a skin layer (also referred to as a "surface layer").

[0097] <<Base Fabric>> The base fabric is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include nonwoven fabric, woven fabric, and knitted fabric.

[0098] The material for the base fabric is not particularly limited and can be selected appropriately depending on the purpose. Examples include polyester, polyethylene, nylon, acrylic, polyurethane, acetate, rayon, polylactic acid, cotton, linen, silk, wool, and glass fiber. These materials may be used alone or in combination of two or more. Among these, polyester is preferred. The base fabric may be composed of a fabric (fiber assembly) formed from fibers in the form of a nonwoven fabric, woven fabric, knitted fabric, or the like. Among these, woven fabric or knitted fabric is preferred because of its low cost and availability. In addition to the above materials, a sheet material having a porous structure obtained by impregnating a fabric with a synthetic resin such as a polyurethane resin may also be used as the base fabric. The base fabric functions to support and reinforce the layer formed on its front side. The presence of the base fabric can increase the strength and shape stability of the laminate sheet. The base fabric may be adhered to the layer formed on its front side with an adhesive.

[0099] The thickness of the base fabric is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 300 μm or more and 1,300 μm or less, and most preferably 400 μm or more and 700 μm or more.

[0100] The laminate may include a resin layer containing the colorant on the base fabric, and a resin layer containing the plant-derived fiber on the side opposite to the base fabric of the resin layer containing the colorant. The base fabric and the resin layer containing the colorant may be in direct contact with each other, or an adhesive layer may be provided between the base fabric and the resin layer containing the colorant.

[0101] <<Adhesive Layer>> The adhesive layer may be provided between the base fabric and the polyvinyl chloride (PVC) layer containing the plant-derived fibers.

[0102] The adhesive layer may include an adhesive, and the adhesive layer may bond the base fabric and the resin layer containing the colorant.

[0103] The thickness of the adhesive layer is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 80 μm or less.

[0104] <<Skin Layer (Surface Layer)>> The skin layer (surface layer) can be provided between the plant-derived fiber-containing polyvinyl chloride (PVC) layer and the surface treatment layer.

[0105] The skin layer (surface layer) may contain polyvinyl chloride or polyurethane. The content of polyvinyl chloride or polyurethane in the surface layer is not particularly limited and may be appropriately selected depending on the purpose.

[0106] The thickness of the surface layer is not particularly limited and can be appropriately selected depending on the purpose, but is preferably 15 μm or more and 30 μm or less.

[0107] The flex resistance of the laminate is preferably equivalent to the flex resistance of a reference vehicle seat in which no plant fibers are added to PVC (a reference vehicle seat having a polyvinyl chloride (PVC) layer that does not contain plant-derived fibers).

[0108] The flex resistance is tested in accordance with the flex resistance test of JIS K6545. After flexing the sheet 100,000 times at room temperature using a flex resistance tester specified in JIS K6545, the sheet is removed from the clamps and judged as pass / fail. The appearance after flexing (whitening of the flexed portion, degree of cracking) is evaluated in comparison with a reference vehicle seat in which no plant fibers are added to the PVC (a reference vehicle seat having a polyvinyl chloride (PVC) layer containing no plant-derived fibers).

[0109] Among the plant-derived fibers, palm-derived fibers are highly hygroscopic. The moisture absorbed by the palm-derived fibers reduces the strength of the resin layer or the laminate containing the plant-derived fibers. Furthermore, the moisture absorbed by the palm-derived fibers evaporates when heated to form bubbles (water vapor gas), which escape from the resin layer or the laminate, creating holes that reduce the strength of the resin layer or the laminate containing the plant-derived fibers. Even if no bubbles appear to be generated, it is presumed that the moisture absorbed by the palm-derived fibers impairs adhesion to polyvinyl chloride (PVC), reducing the strength of the resin layer containing the plant-derived fibers.

[0110] 1 is a diagram schematically illustrating the layer structure of a laminate 1 according to one embodiment. The laminate 1 can include, in this order, a base fabric 2, an adhesive layer 6, a resin layer 3 containing a colorant, a resin layer 4 containing plant-derived fibers, a skin layer 7, and a surface treatment layer 5.

[0111] (Method for manufacturing laminate) The method for manufacturing the laminate includes a pellet manufacturing step, a plant-derived fiber-containing resin layer forming step, and a laminate forming step, and may further include other steps as necessary. The laminate is as described above in (Laminate).

[0112] The pellet production process is a process in which polyvinyl chloride (PVC), a plasticizer in an amount of 50 parts by mass or more and 200 parts by mass or less per 100 parts by mass of the polyvinyl chloride (PVC), and dried plant-derived fibers are stirred together and pellets are produced using an extruder.

[0113] The plant-derived fiber is as described in the section "Plant-derived fiber" in the section "Resin layer containing plant-derived fiber" in the above-mentioned (Laminate). The plasticizer and polyvinyl chloride (PVC) are as described in the section "Resin layer containing colorant" in the above-mentioned (Laminate).

[0114] The method for stirring the polyvinyl chloride (PVC), the plasticizer, and the dried plant-derived fibers is not particularly limited and can be appropriately selected depending on the purpose. For example, a method may be used in which the dried plant-derived fibers are immersed in a plasticizer and stirred while polyvinyl chloride (PVC) powder is added.

[0115] The method for producing pellets using the extruder is not particularly limited and can be appropriately selected depending on the purpose. For example, a method in which the pellets are melt-kneaded at 150°C using a twin-screw extruder (MD-30 / 19 manufactured by Bausano), and then cut and cooled immediately after being discharged from the extruder can be used.

[0116] The plant-derived fiber-containing resin layer forming step is a step of forming a plant-derived fiber-containing resin layer from the pellets.

[0117] The method for forming a resin layer containing plant-derived fibers from the pellets is not particularly limited and can be selected appropriately depending on the purpose. For example, a method can be used in which all materials such as pellets, resin, plasticizer, and filler are simultaneously placed into a twin roll set to 150°C and sufficiently heated until the temperature stabilizes, followed by melt-kneading for 5 minutes at a set temperature of 150°C, and then rolling using a rolling mill.

[0118] The laminate formation step is a step of forming a laminate having a surface treatment layer, a resin layer containing the plant-derived fiber, and a resin layer containing a colorant.

[0119] The method for forming the laminate is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include a calendar method and a casting method.

[0120] The calendering method is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include a method in which a polyvinyl chloride (PVC) compound obtained by suspension polymerization (PVC) to which plant-derived fibers, plasticizers, fillers, etc. are added is rolled using a calender roll to form a polyvinyl chloride (PVC) compound, and the resulting polyvinyl chloride (PVC) layer is laminated on a base fabric.Specific examples include a method in which an adhesive is applied to one surface of the plant-derived fiber-containing resin layer, and the resulting layer is laminated with a base fabric to obtain a laminate having a plant-derived fiber-containing resin layer, an adhesive layer, and a base fabric in this order, a surface layer is applied to the surface of the plant-derived fiber-containing resin layer of the resulting laminate opposite the adhesive layer, and the resulting laminate is dried, and a surface treatment layer is applied to the surface of the surface layer opposite the plant-derived fiber-containing resin layer, and the resulting laminate is dried.

[0121] The casting method is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include a method in which a vinyl chloride paste sol obtained by adding plant-derived fibers, plasticizers, fillers, etc. to polyvinyl chloride (PVC) obtained by emulsion polymerization (paste polymerization) is coated on release paper or the like, and the polyvinyl chloride (PVC) layer obtained by heat gelation is laminated on a base fabric. Even by casting, it is possible to produce the laminate of the present invention by sequentially laminating on release paper, etc., but for efficient mass production, the specific calendar method described above is preferably used.

[0122] (Synthetic Leather) The synthetic leather of the present invention comprises the laminate of the present invention and a base fabric.

[0123] The laminate (the laminate of the present invention) is as described above in (Laminate). The base fabric is as described above in <<Base fabric>> of <<Other layers>> of (Laminate).

[0124] (Car seat) The car seat of the present invention comprises the synthetic leather of the present invention. The synthetic leather (synthetic leather of the present invention) is as described above in (Synthetic Leather). The vehicle seat of the present invention comprises the laminate of the present invention. The laminate of the present invention is suitable for use as a vehicle seat when it exhibits a bending resistance test at a level equivalent to that of a reference vehicle seat in which no plant fibers are added to PVC (a reference vehicle seat having a polyvinyl chloride (PVC) layer containing no plant-derived fibers).

[0125] The vehicle seat is a synthetic leather containing plant-derived fibers. The vehicle seat may include, on the base fabric, a resin layer containing the colorant and a resin layer containing the plant-derived fibers, and a surface treatment layer may be provided on the opposite side of the resin layer containing the plant-derived fibers from the base fabric. The resin layer containing the plant-derived fibers and the surface treatment layer may be in direct contact with each other, or the other layer may be provided between the resin layer containing the plant-derived fibers and the surface treatment layer.

[0126] The base fabric, the resin layer containing the colorant, the resin layer containing plant-derived fibers, the surface treatment layer, and the other layers are as described above in (Laminate).

[0127] Examples of the present invention will be described below, but the present invention is not limited to these examples in any way.

[0128] Production Example 1: Production of Plant-Derived Fiber 1 A coconut fiber raw material (long fiber) several tens of centimeters in length was screened using a cutter mill with a φ2 mm screen pass, then screened using a cutter mill with a φ0.5 mm screen pass, and then passed twice through a mesh with an opening of 318 μm. The resulting particles (Plant-Derived Fiber 1) had a number-average major axis (number-average major axis of the plant-derived fibers in the raw material) of 0.65 mm and a number-average minor axis (number-average minor axis of the plant-derived fibers in the raw material) of 0.21 mm.

[0129] The obtained plant-derived fiber 1 (coconut fiber powder) was dried for 70 hours in a dryer set at a temperature of 110° C. The moisture content of the plant-derived fiber (coconut fiber powder) immediately after drying was 1.03% by mass, as measured using an infrared moisture meter, FD-600 (manufactured by Kett Electric Laboratory Co., Ltd.).

[0130] <Test Example 1-1: Moisture absorption test 1 of plant-derived fiber> 1. The tare of the weighing container was weighed, and the plant-derived fiber 1 produced in Production Example 1 was weighed. 2. The fiber was dried for 2.5 hours in a dryer set to a temperature of 105°C. 3. After drying, the fiber was weighed. 4. The fiber was placed in a thermostatic chamber set to a temperature of 20°C and a humidity of 45%. 5. The fiber was weighed on a balance inside the thermostatic chamber (including the tare). 6. The initial value was measured and recorded. 7. Thereafter, the weighed value was recorded every minute. 8. The weighed value was recorded until it stabilized and no longer changed. 9. After 141 minutes had passed, the fiber was dried for 45 minutes in a dryer set to a temperature of 105°C. The moisture content (moisture absorption rate) was calculated from each weighed value, and the results are shown in Figure 3 (45%).

[0131] Test Example 1-2: Moisture absorption test 2 of coconut fiber powder A moisture absorption test was carried out in the same manner as Test Example 1-1, except that the temperature of the thermostatic chamber was set to 20° C. and humidity to 65%, and after 101 minutes, the powder was dried for 2.5 hours in a dryer set to a temperature of 105° C. The results are shown in Figure 3 (65%).

[0132] Test Example 1-3: Moisture absorption test 3 of coconut fiber powder A moisture absorption test was carried out in the same manner as Test Example 1-1, except that the temperature of the thermostatic chamber was set to 20° C. and humidity to 80%, and after 171 minutes had elapsed, the powder was dried for 1.1 hours in a dryer set to a temperature of 105° C. The results are shown in Figure 3 (80%).

[0133] 3, at a humidity of 45%, the moisture absorption rate reached 7.92% by mass after 140 minutes, and then reached 0.90% by mass after 45 minutes of drying; at a humidity of 65%, the moisture absorption rate reached 12.49% by mass after 100 minutes, and then reached 0.63% by mass after 2.5 hours of drying; and at a humidity of 80%, the moisture absorption rate reached 16.59% by mass after 170 minutes, and then reached 0.33% by mass after 1.1 hours of drying. These results demonstrate that coconut fiber powder is highly hygroscopic, and exhibits extremely high moisture absorption in a short period of time (10% by mass in approximately 30 minutes under conditions of a temperature of 20°C and a humidity of 45%).

[0134] <Production of Pellets> Pellets 1 were produced using the following materials: PVC TK-1300 (manufactured by Shin-Etsu Chemical Co., Ltd.) 100 parts by mass Plasticizer: dialkyl phthalate 100 parts by mass Plant-derived fiber 1 produced in Production Example 200 parts by mass (equivalent to 50% by mass) The dried plant-derived fiber 1 was immersed in the plasticizer, stirred while the polyvinyl chloride (PVC) powder was added, and melt-kneaded at 150°C using a twin-screw extruder (MD-30 / 19 manufactured by Bausano), and immediately after being discharged from the extruder, the pellets were cut and cooled to obtain polyvinyl chloride (PVC) pellets 1 containing plant-derived fiber.

[0135] Production Example 2: Production of Plant-Derived Fibers 2 to 9, and Production of Pellets 1 to 11 By changing the conditions, such as changing the screen opening of the cutter mill and gradually narrowing the clearance between the screen and the rotor, plant-derived fibers 2 to 9 with different number-average major diameters and number-average minor diameters were obtained in the same manner as in Production Example 1. In the same manner as in Production Example 1, plant-derived fibers with different number-average major diameters (number-average major diameter of the plant-derived fibers in the raw materials) and number-average minor diameters (number-average major diameter of the plant-derived fibers in the raw materials) were pelletized to obtain pellets 1 to 11. Note that for pellets 6 and 7, the amount of plasticizer shown in Table 1 was used. A list of pellets 1 to 11 is shown in Table 1.

[0136]

[0137] Example 1: Production of Resin Layer 1 Containing Plant-Derived Fibers Production of Resin Layer 1 Containing Plant-Derived Fibers All of the following materials were simultaneously charged into a twin roll set to 150°C and sufficiently heated until the temperature stabilized, and melt-kneading was initiated. After charging, the materials were melt-kneaded for 5 minutes at a set temperature of 150°C, and then rolled using a rolling mill to produce a resin layer (thickness 250 μm) containing plant-derived fibers. PVC TK-1300 (manufactured by Shin-Etsu Chemical Co., Ltd.) 100 parts by mass Plasticizer: dialkyl phthalate 90 parts by mass Filler: calcium carbonate 10 parts by mass Pellet 1 8.2 parts by mass (equivalent to a plant-derived fiber content of 1.96% by mass)

[0138] <Production of Resin Layer A Containing Colorant> A resin layer (thickness 250 μm) containing a colorant was produced using the following materials: PVC TK-1300 (manufactured by Shin-Etsu Chemical Co., Ltd.) 100 parts by mass, Plasticizer: Dialkyl phthalate 90 parts by mass, Filler: Calcium carbonate 10 parts by mass, Flame retardant: Antimony trioxide 10 parts by mass, Carbon black 18 parts by mass

[0139] <Production of Laminate> A resin layer 1 containing plant-derived fibers and a resin layer A containing a colorant were prepared, and a base fabric (a polyester fabric), the resin layer 1 containing plant-derived fibers, and the resin layer A containing a colorant were rolled up (raw roll). The following steps were continuously carried out by supplying the raw roll.

[0140] An adhesive was applied to the surface of the base fabric, and a resin layer A containing a colorant was attached thereto. Next, a resin layer 1 containing plant-derived fibers was further superimposed on the surface of the resin layer A containing the colorant, and two rolls were added to apply heat and pressure (the resin layer A containing the colorant and the resin layer 1 containing plant-derived fibers were bonded together by the action of heat and pressure, without using an adhesive).

[0141] By the above operation, a laminate having, in this order, a plant-derived fiber-containing resin layer 1, a colorant-containing resin layer A, an adhesive layer, and a base fabric was obtained. A surface layer (polyurethane) was applied to the surface of the plant-derived fiber-containing resin layer 1 of the obtained laminate opposite the adhesive layer and dried at 80°C to 100°C. Furthermore, a surface treatment layer (polyurethane) was applied to the surface of the surface layer opposite the plant-derived fiber-containing resin layer 1 and dried, thereby producing a laminate 1.

[0142] The thickness of the base fabric was 490 μm, the thickness of the resin layer 1 containing plant-derived fibers was 250 μm, the thickness of the resin layer A containing a colorant was 250 μm, the thickness of the surface layer was 20 μm, and the thickness of the surface treatment layer was 10 μm. A photograph of the laminate of Example 1 is shown in Figure 2.

[0143] Examples 2 to 5 Laminates were produced in the same manner as in Example 1 using the combinations shown in Table 2, except that pellet 1 in Example 1 was replaced with pellets 2 to 5, respectively.

[0144] <Example 6> A laminate was produced in the same manner as in Example 1, except that in producing the resin layer containing plant-derived fibers, 3.82 parts by mass of pellet 1 was used to adjust the plant-derived fiber content of the resin layer containing plant-derived fibers to equivalent to 0.94% by mass.

[0145] <Example 7> A laminate was produced in the same manner as in Example 1, except that in producing the resin layer containing plant-derived fibers, 16.7 parts by mass of pellet 1 was used to adjust the plant-derived fiber content of the resin layer containing plant-derived fibers to equivalent to 3.85% by mass.

[0146] Example 8 A laminate was produced in the same manner as in Example 1, except that 7.18 parts by mass of pellet 6 was used in producing a resin layer containing plant-derived fibers, and the amount of dialkyl phthalate used as a plasticizer was changed from 90 parts by mass to 91 parts by mass in order to adjust the plant-derived fiber content in the resin layer to a value equivalent to 1.96% by mass.

[0147] Example 9 A laminate was produced in the same manner as in Example 1, except that 10.25 parts by mass of pellet 7 was used to produce a resin layer containing plant-derived fibers, and the amount of dialkyl phthalate used as a plasticizer was changed from 90 parts by mass to 87.9 parts by mass in order to adjust the plant-derived fiber content in the resin layer to a value equivalent to 1.96% by mass.

[0148] Comparative Example 1 A laminate was produced in the same manner as in Example 1, except that wood chips (number-average aspect ratio 1.1, number-average major axis 0.23 mm, number-average minor axis 0.21 mm) pulverized by a jet mill were used instead of pellets 1 used in Example 1.

[0149] Comparative Example 2 A laminate was produced in the same manner as in Example 1, except that a transparent layer containing no colorant was used instead of the resin layer A containing the colorant used in Example 1.

[0150] Comparative Example 3 A laminate was produced in the same manner as in Example 1 (adjusting the amount of added fiber to be 1.96% by mass), except that instead of pellets 1 used in Example 1, white plastic pieces (white PET film with a thickness of 0.09 mm cut to have a number-average aspect ratio of 2.0, a number-average major axis of 0.6 mm, and a number-average minor axis of 0.3 mm) were used.

[0151] Comparative Examples 4 to 7 Laminates were produced in the same manner as in Example 1 using the combinations shown in Table 2, except that pellet 1 in Example 1 was replaced with pellets 8 to 11, respectively.

[0152] Comparative Example 8 A laminate was produced in the same manner as in Example 1, except that a resin layer containing plant-derived fibers was produced according to the following recipe without using pellets. The plant-derived fibers produced in Production Example 1 were used after being left to stand at room temperature and humidity for 1 hour. PVC TK-1300 (manufactured by Shin-Etsu Chemical Co., Ltd.) 100 parts by mass Plasticizer: dialkyl phthalate 90 parts by mass Filler: calcium carbonate 10 parts by mass Plant-derived fibers produced in Production Example 1 4 parts by mass (equivalent to 1.96% by mass)

[0153] Comparative Example 9 A laminate was produced in the same manner as in Example 1, except that no pellets were used and 16.7 parts by mass of the plant-derived fiber produced in Production Example 1 was used to adjust the plant-derived fiber content to a value equivalent to 3.85% by mass. The plant-derived fiber produced in Production Example 1 was left to stand at room temperature and humidity for 1 hour before use.

[0154] Comparative Example 10 A laminate was produced in the same manner as in Example 1, except that pellets were not used and 49 parts by mass of the plant-derived fiber produced in Production Example 1 was used to adjust the plant-derived fiber content to a value equivalent to 9.98% by mass. The plant-derived fiber produced in Production Example 1 was left to stand at room temperature and humidity for 1 hour before use.

[0155] <Tensile Strength and Elongation> Using the resin layers containing plant-derived fibers of Examples 1 to 10 and Comparative Examples 1 to 10, tensile strength and elongation were tested according to the dumbbell test of JIS K 6251, and evaluated using the following indices. Dumbbell-shaped test pieces were prepared in accordance with JIS K 6250, Section 8 (Collection and Preparation of Test Pieces). The dumbbell test pieces were attached to a tensile tester, and the maximum load (tensile strength) and elongation until the test pieces broke were measured. A reference sample (polyvinyl chloride (PVC) layer containing no coconut-derived fibers) was prepared without adding coconut fibers to the PVC, and evaluated according to the following criteria. The results are shown in Table 2. ○: Equivalent to the reference sample △: Less than to 90% of the reference sample ×: Less than 90% of the reference sample

[0156]

[0157] <Constant Load Low Temperature Bending> Using the plant-derived fiber-containing resin layers of Examples 1 to 9 and Comparative Examples 1 to 10, a constant load low temperature bending test was conducted using the device shown in Figure 6, and the test was evaluated according to the following criteria. The test temperature was -20±2°C, the load was 1.96 N, and the number of bending cycles until cracks appeared in the resin layer was measured. A reference sample (a polyvinyl chloride (PVC) layer containing no plant-derived fiber) was prepared without adding coconut fiber to the PVC, and evaluated according to the following criteria. The results are shown in Table 2. ○: Equivalent to the reference sample △: Less than to 90% of the reference sample ×: Less than 90% of the reference sample

[0158] <Flexibility> Using the laminates of Examples 1 to 9 and Comparative Examples 1 to 10, the laminates were flexed 100,000 times at room temperature using a flex resistance tester specified in JIS K6545, after which the laminates were removed from the clamps and judged for pass / fail. In comparison with a reference vehicle seat in which coconut fiber was not added to the PVC (a reference vehicle seat having a polyvinyl chloride (PVC) layer containing no coconut-derived fiber), the appearance after flexion (whitening of the flexed portion, degree of cracking) was evaluated according to the following criteria. The results are shown in Table 2. ○: Equivalent to the reference vehicle seat △: Slightly inferior to the reference vehicle seat ×: Inferior to the reference vehicle seat

[0159] The number-average major axis and number-average minor axis of the plant-derived fibers in the laminate images of Examples 1 to 10 and Comparative Examples 1 to 10 were measured by observing the prepared laminates with an optical microscope. From a photograph of particle images taken at 30x magnification, the number-average major axis (number-average major axis of the plant-derived fibers in the laminate image) and the number-average minor axis (number-average minor axis of the plant-derived fibers in the laminate image) were measured for 300 particles by comparing them with the scale lines, and the arithmetic mean values ​​of the number-average major axis (number-average major axis of the plant-derived fibers in the laminate image), number-average minor axis (number-average minor axis of the plant-derived fibers in the laminate image), and aspect ratio (aspect ratio of the plant-derived fibers in the laminate image) for the 300 particles were calculated. In this case, flake-like dust particles with a diameter of less than 0.10 mm and an aspect ratio of less than 1.5 were excluded from the measurement.

[0160] The major axis is the length of the perpendicular line connecting two parallel lines tangent to the outline of the plant-derived fiber particle image when the distance between the two parallel lines is the largest. The minor axis is the length connecting two intersections of a line parallel to the two parallel lines passing through a half point of the perpendicular line with the outline of the plant-derived fiber particle image. The results are shown in Table 3.

[0161]

[0162] For the laminates of Examples 1 to 10 and Comparative Examples 1 to 10, images of the resin layer containing the plant-derived fibers were taken, and the occupied area ratio, envelopment degree, and number ratio (%) of plant-derived fibers with an envelopment degree of less than 90% were measured. The results are shown in Table 4.

[0163] An image of the resin layer was obtained under the following (image capturing conditions), and the occupied area ratio and envelopment degree of the plant-derived fiber were measured under the following (image processing conditions).

[0164] (Image capture conditions) Digital image acquisition optical microscope: Keyence digital microscope Magnification: 30x magnification when measuring the occupied area ratio, 50x magnification when measuring the envelopment ratio

[0165] (Image processing conditions) Size of processed image: When measuring the occupied area ratio (magnification 30 times), 7.35 mm x 9.80 mm When measuring the envelopment ratio (magnification 50 times), 4.41 mm x 5.88 mm

[0166] The calculation was carried out by the following process using image processing analysis software, WinROOF CLOUD, manufactured by Mitani Shoji.

[0167] <Sampling> 1. Monochrome Imaging When the image was a color image, it was converted into a monochrome image. Monochrome imaging was performed by selecting monochrome imaging processing or RGB (red, green, blue) separation processing from the menu of the image analysis software WinROOF CLOUD manufactured by Mitani Corporation.

[0168] 2. Noise Removal Next, in order to remove fine noise that cannot be seen with the naked eye, processing was performed in noise removal mode under conditions that removed noise of 50 μm or less.

[0169] 3. Density Conversion (Binarization) Next, the image density was adjusted by density conversion so that the outline of the area where the plant-derived fiber was present was clearly defined. It was visually confirmed that (1) the area where the plant-derived fiber was present in the original image and (2) the outline of the image after density conversion (the area where the measurement sample (plant-derived fiber) was present was displayed in white on the screen) completely overlapped. If the density conversion did not result in complete overlap (for example, if the outline of (2) was larger than that of (1) or if the outline of (1) was larger than that of (2)), the range of the input image density for density conversion was adjusted so that the area where the plant-derived fiber was present in the original image and the outline of the image after density conversion completely overlapped.

[0170] 4. Binarization Next, a binarization process was performed. The areas where plant-derived fibers were present were binarized from the other areas, and complete overlap was confirmed visually between (1) the areas where plant-derived fibers were present in the original image and (2) the outline of the binarized image (the areas where the measurement sample (plant-derived fibers) were present were displayed in green on the screen). In automatic binarization mode, if there was no complete overlap (for example, if the outline of (2) was larger than (1) or if the outline of (1) was larger than (2)), the sampling brightness range was adjusted so that the areas where plant-derived fibers were present in the original image and the outline of the binarized image were completely overlapped.

[0171] <Exclusive Area Ratio> Particles were measured from the measurement menu, and the data of the sampled particles was transferred to a spreadsheet software. The total area value of particles having a circle-equivalent diameter of 50 μm or more among the sampled particles was calculated, and this was divided by the area of ​​the entire image to calculate the exclusive area ratio. The average value of the exclusive area ratio calculated from 10 images was used.

[0172] <Envelope Ratio> Particles were measured from the measurement menu, and the data of the sampled particles was transferred to a spreadsheet software. The envelope ratio was calculated from the perimeter and envelope perimeter for each of the sampled particles with a circle-equivalent diameter of 100 μm or more. The average value of the envelope ratios calculated from 10 images was used. At this time, sampling numbers were drawn on the images. This operation made it possible to compare the data of each particle on the image with the data of each sampled particle by sampling number.

[0173] The degree of envelopment is defined by the following formula 1.

[0174]

[0175] The laminates of Examples 1 to 10 and Comparative Examples 1 to 10 were subjected to a heat bubble generation test to measure the presence or absence of bubbles and the area ratio (%). The results are shown in Table 4.

[0176] The heat bubble generation test was performed as follows. The laminate test piece was heated under conditions of 170°C, 0.5 MPa, and 5 minutes, and a digital image was obtained using an optical microscope (Keyence Digital Microscope). Using image processing software capable of binarizing the acquired image, Mitani Corporation's image analysis software WinROOF2021Standard, the image was binarized by dividing it into black dots where bubbles had burst and the rest of the image. The binarization process was performed in automatic binarization mode. The binarized image was colored in a different color to confirm that it overlapped with the black dots in the original image. The bubble area ratio (%) was calculated from the total area of ​​the black dots divided by the total area of ​​the measurement range of the image.

[0177] Forty office workers were selected as panelists, and a taste-based sensory test was conducted to determine whether they could recognize the presence of the added powder in the laminate and whether they felt the laminate was beautiful. The results are shown in Table 5.

[0178]

[0179] The results in Tables 2 to 5 demonstrate that a laminate having a surface-treated layer, a resin layer containing plant-derived fibers, and a resin layer containing a colorant, in which no bubbles are generated in a heat bubble generation test, and in which, in an image of the laminate, the number-average major axis of the plant-derived fibers is 0.3 mm to 1.0 mm, the number-average minor axis of the plant-derived fibers is 0.1 mm to 0.3 mm, and the number-average aspect ratio (major axis / minor axis) of the plant-derived fibers is 1.5 to 10, can provide a laminate that allows the presence of plant-derived materials to be felt in a highly designable manner while at the same time providing strength and durability. Furthermore, it was found that the use of the pellets of the present invention can provide a car seat that is free of bubbles, satisfies strength and durability requirements, and also satisfies envelopment requirements, resulting in an aesthetically pleasing appearance.

[0180] Examples of aspects of the present invention include the following: <1> A laminate having a surface treatment layer, a resin layer containing plant-derived fibers, and a resin layer containing a colorant, wherein the laminate does not generate bubbles in a heat bubble generation test, and wherein an image of the laminate shows that the plant-derived fibers have a number-average major axis of 0.3 mm or more and 1.0 mm or less, a number-average minor axis of 0.1 mm or more and 0.3 mm or less, and a number-average aspect ratio (major axis / minor axis) of the plant-derived fibers is 1.5 or more and 10 or less. <2> The laminate according to <1> above, which does not contain plant-derived fibers having a major axis of 2.0 mm or more. <3> The laminate according to <1>, wherein, in an image of the plant-derived fiber-containing resin layer, the average value of the occupied area ratio of the plant-derived fiber (100 × area of ​​the portion where the plant-derived fiber is present / total area of ​​the portion where the plant-derived fiber is present and other portions) is 3.0% or more and 8.0% or less, the average value of the envelopment degree of the plant-derived fiber (envelopment perimeter (C PERI) / perimeter (PERI)) is 98.0% or more and 99.9% or less, and the number ratio of particles of the plant-derived fiber having an envelopment degree of 90% or less is 3.0% or less. <4> The laminate according to <1>, wherein the plant-derived fiber-containing resin layer contains polyvinyl chloride (PVC). <5> The laminate according to <1>, wherein the plant-derived fiber is palm-derived fiber. <6> A synthetic leather comprising the laminate according to any one of <1> to <5> and a base fabric. <7> A car seat comprising the synthetic leather according to <6>. <8> A method for producing a laminate, comprising: a pellet production step of stirring polyvinyl chloride (PVC), a plasticizer in an amount of 50 parts by mass or more and 200 parts by mass or less per 100 parts by mass of the polyvinyl chloride (PVC), and dried plant-derived fibers, and producing pellets using an extruder; a plant-derived fiber-containing resin layer formation step of forming a resin layer containing the plant-derived fibers from the pellets; and a laminate formation step of forming a laminate having a surface-treated layer, a resin layer containing the plant-derived fibers, and a resin layer containing a colorant.<9> The method according to <8>, wherein the laminate does not generate bubbles in a heating bubble generation test, and an image of the laminate shows that the plant-derived fibers have a number-average major axis of 0.3 mm or more and 1.0 mm or less, a number-average minor axis of 0.1 mm or more and 0.3 mm or less, and a number-average aspect ratio (major axis / minor axis) of the plant-derived fibers is 1.5 or more and 10 or less.

[0181] REFERENCE SIGNS LIST 1 Laminate 2 Base fabric 3 Resin layer containing colorant 4 Resin layer containing plant-derived fibers 5 Surface treatment layer 6 Adhesive layer 7 Skin layer 8A Separated plant-derived fibers 8B Overlapping plant-derived fibers

Claims

A laminate having a surface-treated layer, a resin layer containing plant-derived fibers, and a resin layer containing a colorant, The laminate did not generate bubbles in a heat bubble generation test, In the image of the laminate, The number average major axis of the plant-derived fibers is 0.3 mm or more and 1.0 mm or less, The number average minor axis of the plant-derived fibers is 0.1 mm or more and 0.3 mm or less, A laminate characterized in that the plant-derived fibers have a number-average aspect ratio (major axis / minor axis) of 1.5 or more and 10 or less. The laminate according to claim 1 , which does not contain plant-derived fibers having a major diameter of 2.0 mm or more. 　 In the image of the resin layer containing the plant-derived fiber, the average value of the exclusive area ratio of the plant-derived fibers (100 × area of ​​the portion where the plant-derived fibers are present / total area of ​​the portion where the plant-derived fibers are present and other portions) is 3.0% or more and 8.0% or less, the plant-derived fiber has an average envelopment degree (envelopment perimeter (C PERI) / perimeter (PERI)) of 98.0% or more and 99.9% or less; The laminate according to claim 1 , wherein the ratio of the number of particles of the plant-derived fibers having an envelopment degree of 90% or less is 3.0% or less. 　 The laminate according to claim 1 , wherein the resin layer containing plant-derived fibers comprises polyvinyl chloride (PVC). 　 The laminate according to claim 1 , wherein the plant-derived fibers are palm-derived fibers. 　 A synthetic leather comprising the laminate according to any one of claims 1 to 5 and a base fabric. 　 A car seat comprising the synthetic leather according to claim 6. 　 a pellet production step of stirring polyvinyl chloride (PVC), a plasticizer in an amount of 50 parts by mass or more and 200 parts by mass or less per 100 parts by mass of the polyvinyl chloride (PVC), and dried plant-derived fibers, and producing pellets using an extruder; a plant-derived fiber-containing resin layer forming step of forming a resin layer containing plant-derived fibers from the pellets; a laminate formation step of forming a laminate having a surface treatment layer, a resin layer containing the plant-derived fiber, and a resin layer containing a colorant. 　 The laminate did not generate bubbles in a heat bubble generation test, In the image of the laminate, The number average major axis of the plant-derived fibers is 0.3 mm or more and 1.0 mm or less, The number average minor axis of the plant-derived fibers is 0.1 mm or more and 0.3 mm or less, The method according to claim 8, wherein the plant-derived fibers have a number-average aspect ratio (major axis / minor axis) of 1.5 or more and 10 or less.

Images