Pearl-like leather sheet

Abstract

To provide a pearl-feeling leather-like sheet hard to discolor at a fold line part when the fold line part receives friction in the pearl-feeling leather-like sheet having high pearl feeling.MEANS: A pearl-feeling leather-like sheet is a leather-like sheet including: a fiber substrate; and a resin layer laminated on the fiber substrate, where the resin layer includes an intermediate layer including a first polyurethane, a skin layer laminated on the intermediate layer, and a surface coat layer that the skin layer is coated with, the skin layer is a layer of a thickness of 10-30 μm including a second polyurethane, and 30-45 pts.mass of a pearl pigment to 100 pts.mass of the second polyurethane, and the surface coat layer is a layer of a thickness of 2-5 μm including a third polyurethane having a 10% modulus of 5 MPa or more, and has a surface of Flop Index of 10 or more.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a leather-like sheet having a pearl-like grain surface layer that is excellent in both high pearly feel and abrasion resistance. [Background technology]

[0002] Leather-like sheets such as artificial leather having a grain-finish resin layer are used as materials for bags, clothing, shoes, etc. The grain-finish resin layer of the leather-like sheet is usually colored before use. As a variation of coloring, a pearl-finish leather-like sheet having a grain-finish resin layer imparted with a metallic feel using a pearl pigment is known.

[0003] For example, the following Patent Document 1 discloses a porous sheet having a good pearly feel, which is composed of a base layer (A) made of a fiber aggregate or a fiber aggregate filled with a polymer mainly made of polyurethane elastomer and a porous coating layer made of a polymer mainly made of polyurethane elastomer, a colored layer (B) made of a polymer mainly made of polyurethane elastomer containing 3% by weight to 500% by weight of a pigment or dye based on the polymer and having a thickness of 0.1 to 10 μm, a pearl layer (C) made of a polymer mainly made of polyurethane elastomer containing 10% by weight to 500% by weight of a pearl pigment and 0% by weight to 300% by weight of a dye based on the polymer, having a thickness of 0.2 to 10 μm, and a clear layer made of a polymer mainly made of polyurethane elastomer and having a thickness of 0.5 to 100 μm.

[0004] Furthermore, the following Patent Document 2 discloses a natural leather having a base coat layer, a first color coat layer, a second color coat layer and a top coat layer, all of which are mainly composed of synthetic resin, laminated in that order on the surface of a natural leather substrate, in which the first color coat layer contains 8 to 16% by weight of a chromatic pigment, the second color coat layer contains 3 to 8% by weight of a glittering pigment, 1 to 5% by weight of a chromatic pigment and a crosslinking agent, and the top coat layer contains a crosslinking agent.

[0005] Furthermore, the following Patent Document 3 discloses a grain-finished leather-like sheet comprising a fiber substrate and a polyurethane surface film laminated on the surface of the fiber substrate directly or via another polyurethane layer, the polyurethane surface film containing at least one of a diketopyrrolopyrrole red pigment or an α-phthalocyanine blue pigment, and further comprising a clear polyurethane film layer coating the polyurethane surface film, the clear polyurethane film layer containing a silicone-modified polyurethane. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 51-002785 [Patent Document 2] JP 2013-023646 A [Patent Document 3] WO2020 / 195850 issue Summary of the Invention [Problem to be solved by the invention]

[0007] In order to improve the design of pearlescent leather-like sheets, a higher pearlescent feeling is required. To improve the pearlescent feeling, it is necessary to blend a larger amount of pearl pigment. However, blending a larger amount of pearl pigment causes a problem of reduced abrasion resistance of the surface. In particular, the abrasion resistance of the folded portion is reduced, and there is a problem of discoloration of the folded portion when the folded portion is subjected to friction.

[0008] To provide a pearl-finished leather-like sheet having a high pearly feel, the folds of which are less likely to discolor when subjected to friction. [Means for solving the problem]

[0009] One aspect of the present invention is a fiber substrate and a resin laminated to the fiber substrate. Layer andThe resin layer includes an intermediate layer containing a first polyurethane, a surface layer laminated on the intermediate layer, and a surface coating layer attached to the surface layer, and the surface layer includes a second polyurethane and a surface coating layer containing ... The median diameter D50 is 4 to 20 μm. Cool face 30 to 45 parts by mass of the material, The surface coating layer is a layer of 10 to 30 μm thick containing 1, a clear polyurethane layer; The pearlescent leather-like sheet is a layer having a thickness of 2 to 5 μm, which contains a third polyurethane having a 0% modulus of 5 MPa or more, and has a surface with a FlopIndex of 10 or more. Such a pearlescent leather-like sheet is capable of retaining a surface with a high pearlescent feel, in which the folds are less likely to discolor when subjected to friction at the folds.

[0010] The Flop Index is a value that quantifies the flip-flop phenomenon, which is a phenomenon in which the brightness changes with the change in viewing angle. The Flop Index is the brightness (L * 15° , L * 45° and L * 110° ) to obtain the following formula (I):

[0011]

number

[0012] is required from.

[0013] In addition, it is preferable that the resin layer further comprises a cushion layer mainly made of porous polyurethane attached to the fiber base material, from the viewpoint of maintaining high surface properties such as abrasion resistance and bending resistance.

[0014] Furthermore, it is preferable that the intermediate layer contains 10 to 50 parts by mass of a color pigment per 100 parts by mass of the first polyurethane, since this makes it easy to form a colored surface having a high pearly feel.

[0015] In addition, the pearl-finish leather-like sheet was made by pressing the folded edge of the sheet in half against a pressure plate with plain weave cotton cloth 79A attached under a load of 2 lb using a custom-type woven fabric abrasion tester, and the sample stage was moved back and forth 1000 times to perform friction. The L * a * b * Lightness L in color system * Difference in brightness ΔL before and after friction * It is preferable that the value is 3 or less, since it is possible to obtain a pearlescent leather-like sheet in which the folds are less likely to discolor when subjected to friction. Effect of the Invention

[0016] According to the present invention, a pearl-finish leather-like sheet having a high pearly feel is obtained in which the folds are resistant to discoloration when subjected to friction. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a schematic cross-sectional view of a pearlescent leather-like sheet 10 according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] The pearlescent leather-like sheet according to the present invention will be described in detail below along with a manufacturing method thereof according to one embodiment.

[0019] 1 is a schematic cross-sectional view illustrating the layer structure of a pearlescent leather-like sheet 10, which is an example of the pearlescent leather-like sheet of this embodiment. The pearlescent leather-like sheet 10 is made of a fiber base material 1 and a resin layer laminated on the fiber base material 1. 2 and The leather-like sheet has a resin layer 2 including a cushion layer 3 mainly made of porous polyurethane that is applied and laminated on a fiber substrate 1, an intermediate layer 4 mainly made of a first polyurethane, a skin layer 5 laminated on the intermediate layer 4, and a surface coating layer 6 applied to the skin layer 5, and further includes a polyurethane adhesive layer 7 that bonds the cushion layer 3 and the intermediate layer 4. The skin layer 5 is made of a second polyurethane and a polyurethane adhesive layer 7 having a polyurethane adhesive layer 7 of 30 to 45 parts by mass per 100 parts by mass of the second polyurethane. The median diameter D50 of the Cool face Pigments (hereinafter simply referred to as pearl pigments) The surface coating layer 6 is a layer having a thickness of 10 to 30 μm and contains 1, a clear polyurethane layer; The layer is 2 to 5 μm thick and contains a third polyurethane having a 0% modulus of 5 MPa or more. The surface skin layer 5 may contain a coloring pigment 9 other than the pearl pigment 8 as necessary. Such a pearlescent leather-like sheet 10 has a highly pearlescent surface that exhibits a FlopIndex of 10 or more. The pearlescent leather-like sheet is not limited to such a layer structure, and the layer structure is not particularly limited as long as it is a leather-like sheet comprising a fiber base material and a resin layer laminated on the fiber base material, the resin layer including the intermediate layer, the surface skin layer, and the surface coat layer as described above.

[0020] As the fiber substrate, a nonwoven fabric, a woven fabric, a knitted fabric, or a substrate impregnated with polyurethane, such as a conventional artificial leather substrate used in the manufacture of artificial leather or a synthetic leather substrate used in synthetic leather, can be used without any particular limitation. The thickness of the fiber substrate is also not particularly limited, but is preferably, for example, about 0.3 to 3 mm, and more preferably, about 0.5 to 1.5 mm. The type of fiber forming the fiber substrate is also not particularly limited, and can be, for example, nylon fiber, polyester fiber, polyolefin fiber, polyurethane fiber, etc.

[0021] The fiber fineness and shape are not particularly limited. For example, the fiber fineness may be a regular fiber having a fineness of more than 1 dtex, or less than 1 dtex, or even an ultrafine fiber having a fineness of 0.0001 to 0.5 dtex. The fiber shape may be a solid fiber, or a fiber having voids such as a hollow fiber or a lotus root-like fiber.

[0022] The first polyurethane contained in the intermediate layer, the second polyurethane contained in the skin layer, the third polyurethane contained in the surface coat layer, the porous polyurethane contained in the cushion layer, and the polyurethane for the adhesive layer contained in the polyurethane adhesive layer 7 are obtained by reacting urethane raw materials including a polymer polyol, an organic polyisocyanate, and a chain extender. In the production of the pearlescent leather-like sheet, each polyurethane is prepared as an organic solvent solution (e.g., a solution of an organic solvent such as dimethylformamide, methyl ethyl ketone, acetone, or toluene), an aqueous dispersion, an emulsion, or a melt.

[0023] Specific examples of polymer polyols include polyether polyols such as polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and poly(methyltetramethylene glycol); polycarbonate polyols such as polyhexamethylene carbonate diol, poly(3-methyl-1,5-pentylene carbonate) diol, polypentamethylene carbonate diol, and polytetramethylene carbonate diol; polyester polyols such as polyethylene adipate diol, polybutylene adipate diol, polypropylene adipate diol, polybutylene sebacate diol, polyhexamethylene adipate diol, poly(3-methyl-1,5-pentylene adipate) diol, poly(3-methyl-1,5-pentylene sebacate) diol, and polycaprolactone diol, or copolymers thereof. These may be used alone or in combination of two or more.

[0024] Specific examples of organic polyisocyanates include diisocyanates that are difficult to yellow, such as aromatic diisocyanates such as 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, and xylylene diisocyanate polyurethane; non-yellowing diisocyanates such as aliphatic or alicyclic diisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, norbornene diisocyanate, and 4,4'-dicyclohexylmethane diisocyanate. If necessary, polyfunctional isocyanates such as trifunctional isocyanates and tetrafunctional isocyanates may be used in combination. These may be used alone or in combination of two or more.

[0025] Specific examples of the chain extender include diamines such as hydrazine, ethylenediamine, propylenediamine, hexamethylenediamine, nonamethylenediamine, xylylenediamine, isophoronediamine, piperazine and its derivatives, adipic acid dihydrazide, and isophthalic acid dihydrazide; triamines such as diethylenetriamine; tetramines such as triethylenetetramine; diols such as ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,4-bis(β-hydroxyethoxy)benzene, and 1,4-cyclohexanediol; triols such as trimethylolpropane; pentaols such as pentaerythritol; amino alcohols such as aminoethyl alcohol and aminopropyl alcohol. These may be used alone or in combination of two or more. During the chain extension reaction, monoamines such as ethylamine, propylamine, and butylamine; carboxyl group-containing monoamine compounds such as 4-aminobutanoic acid and 6-aminohexanoic acid; and monools such as methanol, ethanol, propanol, and butanol may be used in combination with the chain extender.

[0026] In the pearlescent leather-like sheet 10, the resin layer 2 includes a cushion layer 3 mainly made of porous polyurethane, an intermediate layer 4 mainly made of a first polyurethane, a skin layer 5 laminated on the intermediate layer 4, and a surface coating layer 6 applied to the skin layer 5, and further includes a polyurethane adhesive layer 7 that bonds the cushion layer 3 and the intermediate layer 4 together.

[0027] The cushion layer is formed, for example, by applying a wet-coagulating polyurethane solution to the surface of the fiber substrate, and then immersing the fiber substrate in an aqueous coagulation bath to coagulate the porous polyurethane. The cushion layer may be permeated into the fiber substrate for the purpose of imparting shape stability to the fiber substrate. In this case, the fiber substrate is impregnated with a polyurethane solution in advance, and then coated with the polyurethane solution, and then immersed in an aqueous coagulation bath to coagulate the polyurethane, thereby imparting the porous polyurethane to the inside of the fiber substrate. The thickness of the cushion layer is not particularly limited, but is preferably, for example, about 100 to 600 μm, and more preferably about 200 to 400 μm. The cushion layer may be a non-porous polyurethane layer.

[0028] The intermediate layer 4 and the skin layer 5 are formed by adhering them to the surface of the cushion layer 3, for example, by a dry surface-making method as follows.

[0029] A polyurethane film for forming the surface layer 5 is formed on the release paper. Then, a polyurethane film for forming the intermediate layer 4 is formed on the polyurethane film of the surface layer 5. In this manner, the intermediate layer 4 formed on the release paper and the surface layer 5 laminated on the intermediate layer 4 are formed. The intermediate layer 4 may be a layer consisting of only a single layer, or may have a laminated structure in which multiple layers containing different polyurethanes are laminated.

[0030] A polyurethane adhesive is then applied to the intermediate layer 4, the solvent is completely or incompletely removed and the layer is dried to form a semi-cured adhesive layer, the semi-cured adhesive layer is bonded to the surface of the cushion layer 3 and pressed, and the semi-cured adhesive layer is then cured to form a laminated structure of the cushion layer 3, the intermediate layer 4, and the skin layer 5 via the polyurethane adhesive layer 7. The release paper is then peeled off from the surface of the skin layer 5 to obtain a base material for a pearlescent leather-like sheet comprising the fiber base material, the cushion layer 3 laminated on the fiber base material, the intermediate layer 4, and the skin layer 5.

[0031] The surface layer 5 is a polyurethane layer having a thickness of 10 to 30 μm, which contains a second polyurethane and 30 to 45 parts by mass of a pearl pigment per 100 parts by mass of the second polyurethane, and is used to impart a pearlescent feel to the surface. By using such a polyurethane layer as the surface layer, it is possible to obtain a pearlescent leather-like sheet having a surface with a high pearlescent feel, which exhibits a Flop Index of 10 or more, as described below.

[0032] The type of the second polyurethane is not particularly limited, but a polycarbonate polyurethane containing a polycarbonate polyol as a polymer polyol unit and an aliphatic diisocyanate as an organic polyisocyanate unit, particularly a silicone-modified polycarbonate polyurethane, is preferred from the viewpoint of excellent abrasion resistance. The modulus of the second polyurethane is also not particularly limited, but for example, the 100% modulus is preferably about 2 to 8 MPa.

[0033] Pearl pigments are thin-plate pigments that exhibit pearlescent luster accompanied by interference colors due to multiple reflections of light. Specific examples include thin-plate mica-based pearl pigments (e.g., Iriodin (registered trademark) manufactured by Merck) in which the surface of thin-plate particles of natural or synthetic mica is coated with metal oxides such as titanium dioxide, silicon oxide, and iron oxide, resin-based pearl pigments in which two or more resin layers with different refractive indices are laminated, pearl powder, powder of the inner wall of a shell, fish scale foil, etc. Particle diameter of pearl pigments teeth, The median diameter D50 is preferably selected from the range of 4 to 20 μm.

[0034] The content of the pearl pigment in the surface layer is 30 to 45 parts by mass, preferably 35 to 40 parts by mass, based on 100 parts by mass of the second polyurethane. By including the pearl pigment in the surface layer at such a relatively high ratio, the surface of the pearl-finished leather-like sheet can be given a pearly feel with a Flop Index of 10 or more as described above. If the content of the pearl pigment in the surface layer is less than 30 parts by mass based on 100 parts by mass of the second polyurethane, it becomes difficult to obtain a surface with a Flop Index of 10 or more, and if it exceeds 45 parts by mass, the bending resistance and abrasion resistance of the surface decrease.

[0035] The skin layer has a thickness of 10 to 30 μm, preferably 15 to 25 μm. If the skin layer is more than 30 μm thick, the colored intermediate layer is concealed and the color becomes whitish, and if the skin layer is too thin, the abrasion resistance decreases and it becomes difficult to obtain a surface exhibiting a Flop Index of 10 or more.

[0036] The pearlescent leather-like sheet of this embodiment, by being provided with such a skin layer, can realize a surface showing a Flop Index of 10 or more. The Flop Index is high when the thin-plate-like pearl pigment covers and conceals the surface of the skin layer to a high degree, and the pearl pigment does not form irregularities on the surface of the skin layer, resulting in high smoothness. To obtain such a surface, the thickness of the skin layer and the blending ratio of the pearl pigment are adjusted to the above-mentioned values.

[0037] The content of pearl pigment in the surface layer per unit area is 3 to 10 g / m 2 , and even 5 to 8 g / m 2 This is preferable because it is easier to obtain a surface that exhibits a Flop Index of 10 or more.

[0038] The surface layer may contain other color pigments other than the pearl pigment, so long as they do not impair the effects of the present invention. The type of other color pigment is not particularly limited, but organic pigments that do not impair the brightness of the pearl pigment are preferred. Specific examples include diketopyrrolopyrrole pigments such as diketopyrrolopyrrole red pigments, anthraquinone pigments, perylene pigments, and phthalocyanine pigments such as α-phthalocyanine blue pigments. When the surface layer contains a color pigment, the total content of the color pigment and the pearl pigment in the surface layer is preferably 50 parts by mass or less, and more preferably 45 parts by mass or less, relative to 100 parts by mass of the second polyurethane, from the viewpoint of preventing a decrease in abrasion resistance.

[0039] The intermediate layer 4 contains a first polyurethane, and preferably contains a color pigment. Such an intermediate layer is a layer that adjusts the color visible from the surface and provides cushioning properties without blending a large amount of color pigment in the surface layer.

[0040] The type of the first polyurethane is not particularly limited, but is preferably a polyether polyurethane containing a polyether polyol as a polymer polyol unit and an aromatic diisocyanate as an organic polyisocyanate unit, which is difficult to yellow, from the viewpoint of flexibility and durability. The modulus of the second polyurethane is not particularly limited, but is preferably, for example, about 2 to 5 MPa.

[0041] When the intermediate layer contains a color pigment, the type of the color pigment contained in the intermediate layer is not particularly limited. Specific examples of the color pigment include diketopyrrolopyrrole pigments such as diketopyrrolopyrrole red pigments, anthraquinone pigments, perylene pigments, and phthalocyanine pigments such as α-phthalocyanine blue pigments.

[0042] When the intermediate layer contains a coloring pigment, it is preferable for the intermediate layer to contain 10 to 50 parts by mass, or even 20 to 30 parts by mass, of the coloring pigment per 100 parts by mass of the first polyurethane, in order to sufficiently adjust the color visible from the surface.

[0043] The thickness of the intermediate layer is not particularly limited, but is preferably 10 to 50 μm, and more preferably 20 to 30 μm.

[0044] Moreover, the polyurethane adhesive layer 7 is a layer containing polyurethane for adhering the cushion layer 3 and the intermediate layer 4. The thickness of the polyurethane adhesive layer is not particularly limited, but it is preferable that the thickness be 20 to 60 μm, and preferably 30 to 50 μm, in order to obtain sufficient adhesion.

[0045] The release paper is then peeled off to expose the surface of the skin layer on the surface of the substrate of the pearl-finish leather-like sheet thus obtained, and an ink containing a third polyurethane having a 10% modulus of 5 MPa or more is applied by a coating means such as gravure printing and then dried to form a surface coating layer having a thickness of 2 to 5 μm adhered to the skin layer.

[0046] The surface coat layer is a clear polyurethane layer that is applied to the skin layer, does not substantially contain color pigments or pearl pigments, and is mainly composed of a third polyurethane with a 10% modulus of 5 MPa or more, and has a thickness of 2 to 5 μm. By applying such a surface coat layer to the skin layer, a pearl-finished leather-like sheet is obtained in which the folded parts are less likely to discolor when subjected to friction at the folded parts, even if the skin layer contains a high proportion of pearl pigment.

[0047] The type of the third polyurethane is not particularly limited as long as its 10% modulus is 5 MPa or more. The 10% modulus of the third polyurethane is preferably 5 to 15 MPa. The 100% modulus of the third polyurethane is preferably 8 to 20 MPa, more preferably 9 to 17 MPa. By having the 10% modulus of the third polyurethane be 5 MPa or more, even if the surface layer contains a high proportion of pearl pigment, the fold portion is less likely to discolor when subjected to friction at the fold portion. On the other hand, if the 10% modulus of the polyurethane contained in the surface coat layer is less than 5 MPa, the fold portion is more likely to discolor when subjected to friction at the fold portion.

[0048] The surface coating layer has a thickness of 2 to 5 μm. If the thickness of the surface coating layer is less than 2 μm, the effect of preventing the fold portion from discoloring when subjected to friction is reduced. If the thickness of the surface coating layer is more than 5 μm, the texture becomes hard and the flex resistance is reduced.

[0049] In this way, the pearlescent leather-like sheet of this embodiment is obtained. By providing the resin layer having the layer structure described above, the pearlescent leather-like sheet of this embodiment is less likely to discolor the folded portion when subjected to friction, even if the flop index of the surface is 10 or more.

[0050] Here, a surface showing a Flop Index of 10 or more is a surface of a surface coating layer of a pearl-finish leather-like sheet, which is measured at angles of 15 degrees, 45 degrees, and 110 degrees using a multi-angle spectrophotometer. * a * b * Lightness L calculated from the coordinate values ​​of the color system * Value (L * 15° , L * 45° and L * 110° ) to obtain the following formula (I):

[0051]

number

[0052] The Flop Index of the surface of the pearlescent leather-like sheet of this embodiment is 10 or more, and preferably 10.5 or more. The flop index is high because the thin plate-like pearl pigment covers and conceals the inner surface of the skin layer to a high degree, and the pearl pigment does not form irregularities on the surface of the skin layer, resulting in high smoothness.

[0053] The pearlescent leather-like sheet of this embodiment has a resin layer having the layer structure described above, so that the folds in the pearlescent leather-like sheet, which has a high pearly feel, are less likely to discolor when subjected to friction at the folds.

[0054] The degree to which the folds are less likely to discolor when subjected to friction at the folds is, for example, the L value when the edge of the fold of a pearl-finish leather-like sheet is pressed against a pressure plate with a thick cotton weave (plain weave cotton cloth 79A) attached with a load of 2 lb when folded in half and the sample stage is moved back and forth 1000 times to cause friction. * a * b * Lightness L in color system * The difference in brightness ΔL * It is preferable that the lightness difference ΔL is 3 or less, and more preferably 2 or less. In such a test, the pearlescent leather-like sheet of the present embodiment has a small lightness difference ΔL * By adjusting the color of the fold to show the above-mentioned characteristic, the fold is less likely to discolor when subjected to friction.

[0055] Leather-like sheets are processed into products of various shapes, such as by folding them into a box shape or molding them into a pipe shape. The folds formed by processing in this way have a problem in that discoloration is noticeable when they rub against floors, clothes, other parts of the product, etc., and the product quality is easily impaired. The pearl-finish leather-like sheet of this embodiment described above is preferably used as a material for bags such as school bags, which require a high pearly feel and are preferred for the folds not to discolor when subjected to friction. EXAMPLES

[0056] The present invention will be described in more detail below with reference to examples, although the scope of the present invention is not limited to these examples in any way.

[0057] [Example 1] An islands-in-sea composite fiber containing 45 parts by mass of 6-nylon (sea component) and 55 parts by mass of polystyrene (island component) was melt spun, stretched 3 times, treated with a fiber oil, mechanically crimped, and then dried. The crimped fiber was cut to 51 mm and made into a 3 dtex staple, which was then formed into a web, which was then alternately combined from both sides to form a web with approximately 500 punches / cm. 2 The nonwoven fabric had a basis weight of 350 g / m 2 The apparent specific gravity was 0.17. This entangled nonwoven fabric was treated with a 4% aqueous solution of polyvinyl alcohol, compressed and fixed to a thickness of approximately 1.3 mm, and the surface was buffed to make it smooth. The fabric was then impregnated with a 13% concentration solution of polyurethane, mainly composed of polyester-based polyurethane, in dimethylformamide (hereinafter referred to as DMF). The surface was then further impregnated with the same polyurethane solution at a solid content of 100 g / m2. 2 After applying the amount of polyurethane to the fiber, the fiber was immersed in a mixture of DMF and water to wet-solidify the porous polyurethane. The islands were then dissolved and removed in hot toluene to convert the islands-in-the-sea composite fiber into a hollow fiber. In this way, a fiber substrate was obtained in which the cushion layer was laminated on the surface. The thickness of the cushion layer was 300 μm.

[0058] Next, a polyurethane composition solution containing 100 parts by mass of a 20% solution of the second polyurethane, 8 parts by mass of a pearl pigment, and 0.2 parts by mass of a red pigment was applied to the surface of a release paper (R-70 manufactured by Lintec Corporation) so that the thickness after drying was 20 μm, and then dried to form a skin layer. The second polyurethane was a silicone-modified polycarbonate-based polyurethane containing a polycarbonate-based polyol as a polymer polyol unit and an aliphatic diisocyanate as an organic polyisocyanate unit.

[0059] Then, a polyurethane composition solution containing 100 parts by mass of a 30% solution of the first polyurethane, 30 parts by mass of a red vehicle containing 10% by mass of anthraquinone pigment, 10 parts by mass of a white vehicle containing titanium dioxide, 30 parts by mass of DMF, and 30 parts by mass of methyl ethyl ketone was applied to the surface of the skin layer formed on the release paper so that the thickness after drying was 20 μm, and then dried to form an intermediate layer having a thickness of 20 μm. The first polyurethane was a polyether-based polyurethane that was resistant to yellowing and contained a polyether-based polyol as a polymer polyol unit and an aromatic diisocyanate as an organic polyisocyanate unit.

[0060] Then, a polyurethane adhesive was applied to the surface of the intermediate layer formed on the release paper, and the adhesive layer was dried at 120°C for 2 minutes to evaporate the solvent, forming a semi-cured adhesive layer with a thickness of 50 μm. The semi-cured adhesive layer formed on the release paper was then attached to a cushion layer laminated on a fiber substrate to produce a laminated intermediate body. The polyurethane adhesive contains 100 parts by mass of a crosslinking polyurethane adhesive plus a crosslinking agent and a crosslinking accelerator as adhesive components, and contains 5 parts by mass of DMF and 10 parts by mass of ethyl acetate as solvents. The semi-cured adhesive layer was then infiltrated into the cushion layer while being pressed by a roll having a clearance of about 65% of the total thickness of the laminated intermediate body, 1.6 mm. The laminated intermediate body was then dried at 130°C for 3 minutes, aged at 50°C for 3 days, and then the release paper was peeled off to obtain a pink pearlescent leather-like sheet substrate.

[0061] A coating solution containing a third polyurethane was applied to the surface of the epidermis layer of the substrate of the pearlescent leather-like sheet so that the thickness after drying was about 2 μm, and then dried to form a surface coat layer. The coating solution containing the third polyurethane was SP-215NS manufactured by Dainichi Seika Chemicals Co., Ltd., which contains a polyester-based polyurethane with a 10% modulus of 5.4 MPa and is difficult to yellow. In this way, a pearlescent leather-like sheet was obtained.

[0062] The resulting pearlescent leather-like sheet was evaluated as follows.

[0063] (Measurement of polyurethane modulus) A polyurethane film of about 400 μm in thickness was prepared from the polyurethane used in each Example and Comparative Example, and cut into a 2.5 cm width to measure strength and elongation using a precision universal testing machine (autograph). The strengths at 10%, 20%, and 100% elongation of the obtained SS curve were read and divided by the cross-sectional area obtained from the film thickness and 2.5 cm width to calculate the 10% modulus, 20% modulus, and 100% modulus (MPa).

[0064] (Measurement of thickness of each layer) The cross section of the pearlescent leather-like sheet in the thickness direction was observed with a scanning electron microscope at 800x magnification, and the images were saved. The images were taken at five randomly selected locations. The thickness of each layer was measured for the five images obtained.

[0065] (Measurement of Flop Index) The surface of the surface coating layer of the pearlescent leather-like sheet is measured at angles of 15 degrees, 45 degrees, and 110 degrees using a multi-angle spectrophotometer. * a * b * Lightness L calculated from the coordinate values ​​of the color system * Value (L * 15° , L * 45° and L * 110° ) to obtain the following formula (I):

[0066]

number

[0067] was obtained from.

[0068] (L of fold wear * (measurement of value) The fold abrasion was measured using a custom-type fabric abrasion tester based on JIS L1096 general fabric testing method. The edge of a pearl-finish leather-like sheet folded in half was pressed against a pressure plate equipped with thick cotton fabric (plain weave cotton cloth 79A) with a load of 2 lb, and the sample stage was moved back and forth 1000 times to cause friction.

[0069] The color measurements were performed using a spectrophotometer in accordance with JIS Z 8722:2009 (Geometric methods of color - Reflective and transmitted object color, 5. Spectrophotometric methods) and JIS Z 8781-4:2013 (Colorimetry - Part 4: CIE 1976 L * a * b * Using the formulas (1) to (9) shown in "4.1 Basic Coordinates" of the color space, * a * b * The measurements were performed three times, and the average value was shown as the result.

[0070] (Bending resistance) A flex test was performed with a flexometer at 20°C using a pearlescent leather-like sheet, and the occurrence of surface cracks was confirmed every 100,000 cycles of bending. The cracks were visually confirmed using a magnifying glass. If cracks were confirmed at 100,000 cycles, it was judged as "less than 100,000 cycles," if cracks were confirmed at 200,000 cycles, it was judged as "100,000 cycles," and other judgments were made at each "100,000 cycles" in the same manner. The test was terminated at 500,000 cycles, and if no cracks were confirmed, it was judged as 500,000 cycles or more.

[0071] (Wear resistance) A test piece was prepared by attaching double-sided tape to the back side of the pearl-finished leather-like sheet and cutting it into a circle with a diameter of 10.6 cm, and then weighed precisely on a specified balance. Next, the test piece was set on a turntable and attached to the vertical drive shaft of a Taber abrasion tester. Then, an arm equipped with an abrasive wheel (H-22 (manufactured by Daito Electron Co., Ltd.)) was lowered onto the measurement surface, and the pearl-finished surface of the test piece was abraded under conditions of a load of 1 kg and a rotation speed of 1000 times. After abrasion up to 1000 rotations, the test piece was removed, the abrasion debris attached to the test piece was thoroughly removed with a brush, and the test piece was weighed precisely on a specified balance, and the abrasion loss (mg) was measured. The abrasion loss was calculated as the difference in weight before and after abrasion. The average value of the results of three measurements was taken as the abrasion loss of the pearl-finished leather-like sheet.

[0072] The results are shown in Table 1 below.

[0073] [Table 1]

[0074] [Example 2] A pearlescent leather-like sheet was obtained and evaluated in the same manner as in Example 1, except that a coating solution containing a non-yellowing polycarbonate-based polyurethane with a 10% modulus of 12.3 MPa (SSTC-7 manufactured by Dainichi Seikagaku Kogyo Co., Ltd.) was used as the third polyurethane-containing coating solution in Example 1. The results are shown in Table 1.

[0075] [Example 3] A pearlescent leather-like sheet was obtained and evaluated in the same manner as in Example 1, except that a coating solution containing a non-yellowing silicone-modified polycarbonate-based polyurethane with a 10% modulus of 6.9 MPa (Leatheroid LU-587 manufactured by Dainichi Seika Chemicals Mfg. Co., Ltd.) was used as the third polyurethane-containing coating solution in Example 1. The results are shown in Table 1.

[0076] [Example 4] A pearlescent leather-like sheet was obtained and evaluated in the same manner as in Example 1, except that the thickness of the surface coating layer was changed from 2.3 μm to 5 μm. The results are shown in Table 1.

[0077] [Example 5] A pearlescent leather-like sheet was obtained and evaluated in the same manner as in Example 2, except that the amount of pearl pigment was changed from 40 parts by mass to 45 parts by mass in Example 2. The results are shown in Table 1.

[0078] [Example 6] A pearlescent leather-like sheet was obtained and evaluated in the same manner as in Example 2, except that the amount of pearl pigment was changed from 40 parts by mass to 30 parts by mass in Example 2. The results are shown in Table 1.

[0079] [Example 7] A pearl-finish leather-like sheet was obtained and evaluated in the same manner as in Example 1, except that the thickness of the surface layer was changed from 20 μm to 10 μm. The results are shown in Table 1.

[0080] [Example 8] A pearl-finish leather-like sheet was obtained and evaluated in the same manner as in Example 1, except that the thickness of the surface layer was changed from 20 μm to 30 μm. The results are shown in Table 1.

[0081] [Comparative Example 1] A pearl-finish leather-like sheet was obtained and evaluated in the same manner as in Example 1, except that the surface coating layer was not formed. The results are shown in Table 1.

[0082] [Comparative Example 2] A pearlescent leather-like sheet was obtained and evaluated in the same manner as in Example 1, except that a coating solution containing a non-yellowing silicone-modified polycarbonate-based polyurethane with a 10% modulus of 2.2 MPa (NY-324 manufactured by DIC Corporation) was used as the third polyurethane-containing coating solution in Example 1. The results are shown in Table 1.

[0083] [Comparative Example 3] A pearlescent leather-like sheet was obtained and evaluated in the same manner as in Example 1, except that a coating solution containing a non-yellowing polycarbonate-based polyurethane with a 10% modulus of 2.7 MPa (NY-360 manufactured by DIC Corporation) was used as the third polyurethane-containing coating solution in Example 1. The results are shown in Table 1.

[0084] [Comparative Example 4] A pearlescent leather-like sheet was obtained and evaluated in the same manner as in Example 1, except that a coating solution containing a polycarbonate-based polyurethane with a 10% modulus of 1.4 MPa and low yellowing was used as the third polyurethane-containing coating solution (SSTC-8014 manufactured by Dainichiseika Chemicals Mfg. Co., Ltd.). The results are shown in Table 1.

[0085] [Comparative Example 5] A pearlescent leather-like sheet was obtained and evaluated in the same manner as in Example 1, except that the thickness of the surface coating layer in Example 2 was changed from 2.5 μm to 1.0 μm. The results are shown in Table 1.

[0086] [Comparative Example 6] An artificial leather was obtained and evaluated in the same manner as in Example 1, except that the amount of the pearl pigment was changed from 40 parts by mass to 20 parts by mass in Example 1. The results are shown in Table 1.

[0087] [Comparative Example 7] An artificial leather was obtained and evaluated in the same manner as in Example 1, except that the amount of the pearl pigment was changed from 40 parts by mass to 50 parts by mass in Example 1. The results are shown in Table 1.

[0088] [Comparative Example 8] A pearlescent leather-like sheet was obtained and evaluated in the same manner as in Example 1, except that the thickness of the surface coating layer was changed from 2.3 μm to 8 μm. The results are shown in Table 1.

[0089] Referring to Table 1, the pearlescent leather-like sheets obtained in Examples 1 to 8 all had a surface with a high pearlescent feel, with a Flop Index of 10 or more, and the brightness difference (ΔL * ) was small, and the folds were less likely to discolor when subjected to friction.

[0090] On the other hand, the pearlescent leather-like sheets obtained in Comparative Example 1, in which no surface coating layer was formed, and Comparative Examples 2 to 4, in which the 10% modulus of the third polyurethane contained in the surface coating layer was less than 5 MPa, all had a surface with a high pearlescent feel with a Flop Index of 10 or more, but the brightness difference (ΔL * ) was large, and the folds were easily discolored when subjected to friction. In addition, the pearlescent leather-like sheet obtained in Comparative Example 5, in which the surface coating layer was too thin, also had a low lightness difference (ΔL * ) was large, and the folds were easily discolored when subjected to friction. In addition, the pearlescent leather-like sheet obtained in Comparative Example 6, in which the content of the pearl pigment in the surface layer was low, had a low brightness difference (ΔL * ) was small, but did not have a high pearly feel with a Flop Index of 10 or more. The pearlescent leather-like sheet obtained in Comparative Example 7, in which the content of the pearl pigment in the surface layer was too high, had low abrasion resistance. The pearlescent leather-like sheet obtained in Comparative Example 8, in which the surface coating layer was too thick, had a hard surface and low flex resistance. [Explanation of symbols]

[0091] 1. Fiber base material 2 Resin layer 3 Cushioning layer 4. Middle Tier 5 Epidermal layer 6 Surface coating layer 7 Polyurethane adhesive layer 8 Pearl Pigments 9. Color Pigments 10 Pearl leather-like sheet

Claims

1. A leather-like sheet comprising a fiber substrate and a resin layer laminated on the fiber substrate, the resin layer includes an intermediate layer including a first polyurethane, a surface layer laminated on the intermediate layer, and a surface coating layer applied to the surface layer, the surface layer is a layer having a thickness of 10 to 30 μm, which contains a second polyurethane and 30 to 45 parts by mass of a pearl pigment having a median diameter D50 of 4 to 20 μm per 100 parts by mass of the second polyurethane; the surface coating layer is a clear polyurethane layer, which is a layer having a thickness of 2 to 5 μm and contains a third polyurethane having a 10% modulus of 5 MPa or more; A pearlescent, silver-finished leather-like sheet having a surface with a Flop Index of 10 or more.

2. 2. The pearlescent grain-finished leather-like sheet according to claim 1, wherein the resin layer further comprises a cushion layer mainly made of porous polyurethane and coated on the fiber base material.

3. 3. The pearlescent grain-finished leather-like sheet according to claim 1, wherein the intermediate layer contains 10 to 50 parts by weight of a coloring pigment based on 100 parts by weight of the first polyurethane.

4. Using a custom type woven fabric abrasion tester, the edge of the folded fabric was pressed against a pressure plate with a plain woven cotton cloth 79A attached with a load of 2 lbs. The sample stage was moved back and forth 1000 times to perform friction. The L ＊ a ＊ b ＊ Lightness L in color system ＊ Difference in brightness ΔL between before and after friction ＊ 4. The pearlescent grain-finished leather-like sheet according to claim 1, wherein the grain-finished leather-like sheet has a grain-finished ...

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