Surface material

Abstract

The present invention aims to provide a surface material that prevents the back side from being visible through it. [Solution] (Composition 1) The nonwoven fabric contains, as constituent fibers, first fibers (hereinafter referred to as fine fibers) containing metal oxide particles having the smallest average fiber diameter, and second fibers (hereinafter referred to as thick fibers) containing metal oxide particles with a larger average fiber diameter. and, (Composition 2) The mass percentage of metal oxide particles contained in the fine fibers relative to the mass of the fine fibers is less than the mass percentage of metal oxide particles contained in the thick fibers relative to the mass of the thick fibers. The surface material, which has both of these components in its nonwoven fabric, is difficult to see through to the back side.

Description

[Technical Field]

[0001] The present invention relates to a surface material comprising a nonwoven fabric. [Background technology]

[0002] In recent years, there has been research into manufacturing interior and exterior materials (hereinafter collectively referred to as interior and exterior materials) by molding laminates, which are formed by bonding a base material and a surface material with an adhesive in between, using methods such as heat molding. However, in interior and exterior materials manufactured in this way, the adhesive present on the back side is sometimes visible through the main surface side derived from the surface material. As a result, the manufactured interior and exterior materials suffer from inferior aesthetic appeal.

[0003] As a conventional technology that can solve such problems, for example, Japanese Patent Publication No. 2003-328247 (Patent Document 1) discloses a nonwoven fabric in which fibers containing metal oxide particles such as titanium oxide particles are included in the constituent fibers. This nonwoven fabric has low visible light transmittance due to the presence of metal oxide particles. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2003-328247 [Overview of the project] [Problems that the invention aims to solve]

[0005] The applicant of this application has examined the invention described in Patent Document 1. However, in order to provide a low-cost surface material, or to provide a light interior and exterior material by reducing the weight of the surface material, for example, by reducing the content of metal oxide particles contained in the constituent fibers of the nonwoven fabric, or by reducing the weight of the nonwoven fabric, the total mass of metal oxide particles contained in the nonwoven fabric decreases, and the visible light transmittance of the nonwoven fabric increases. As a result, the surface material equipped with the nonwoven fabric becomes more transparent on the back side, and in interior and exterior materials manufactured using the surface material, the adhesive present on the back side can sometimes be seen through from the main surface side derived from the surface material.

[0006] Therefore, even when the total mass of metal oxide particles contained in the nonwoven fabric is reduced, there was a need to create a surface material that prevents the back side from being visible through the fabric. [Means for solving the problem]

[0007] The first invention is a surface material comprising a nonwoven fabric, The nonwoven fabric comprises a first fiber having the smallest average fiber diameter and a second fiber having a larger average fiber diameter than the first fiber. The first fiber and the second fiber contain metal oxide particles. The mass percentage of the metal oxide particles contained in the first fiber relative to the mass of the first fiber is less than the mass percentage of the metal oxide particles contained in the second fiber relative to the mass of the second fiber. "Surface material." Furthermore, the second aspect of the present invention is that "both the first fiber and the second fiber are fibers with a circular cross-sectional shape." The surface material described in claim 1. [Effects of the Invention]

[0008] As mentioned above, when the total mass of metal oxide particles contained in a nonwoven fabric (this total mass can be expressed as basis weight) is reduced, the surface material containing the nonwoven fabric tends to be more transparent and the back side is more easily visible.

[0009] Regarding that common technical knowledge, the applicant of this application stated: The nonwoven fabric contains, as constituent fibers, first fibers (hereinafter referred to as fine fibers) containing metal oxide particles with the smallest average fiber diameter, and second fibers (hereinafter referred to as thick fibers) containing metal oxide particles with a larger average fiber diameter. and, The percentage of the total mass of the fine fibers that is comprised of metal oxide particles is less than the percentage of the total mass of the thick fibers that is comprised of metal oxide particles. In the case of having both of these configurations, we found that even if the total mass of metal oxide particles contained in the nonwoven fabric decreases, the surface material having the nonwoven fabric is difficult to see through to the other side.

[0010] Therefore, the surface material of the present invention, which comprises a nonwoven fabric having both of the above-described configurations, can provide an interior and exterior material in which the back side is not visible.

[0011] Furthermore, if the nonwoven fabric of the surface material contains fine and thick fibers, which have a circular cross-sectional shape, as constituent fibers, then, as is clear from the examples, the surface material prevents the back side from being visible. [Modes for carrying out the invention]

[0012] In this invention, various configurations can be appropriately selected, such as the following configuration. Unless otherwise specified, the various measurements described in this invention are performed under normal pressure and a temperature of 25°C. Unless otherwise specified, the various measurement results described in this invention are obtained by measurement to a value one decimal place smaller than the desired value, and the desired value is calculated by rounding this value. For example, if the desired value is to be expressed to the first decimal place, the value is obtained to the second decimal place by measurement, and the obtained second decimal place value is rounded to the first decimal place, and this value is used as the desired value. In addition, the upper and lower limits exemplified in this invention can be combined arbitrarily.

[0013] The surface material according to the present invention includes a non-woven fabric. Therefore, it is rich in flexibility and has excellent formability such as being heat-moldable.

[0014] The constituent fibers of the non-woven fabric can be composed of, for example, polyolefin resins (e.g., polyethylene, polypropylene, polyolefin resins with a structure in which a part of hydrocarbons is substituted with a halogen such as a nitrile group, fluorine, or chlorine), polymethylpentene, styrene resins, polyvinyl alcohol resins, polyether resins (e.g., polyether ether ketone, polyacetal, modified polyphenylene ether, aromatic polyether ketone, etc.), polyester resins (e.g., polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polycarbonate, polyarylate, wholly aromatic polyester resin, etc.), polyimide resins, polyamideimide resins, polyamide resins (e.g., aromatic polyamide resins, aromatic polyether amide resins, nylon resins, etc.), resins having a nitrile group (e.g., polyacrylonitrile, etc.), urethane resins, epoxy resins, polysulfone resins (e.g., polysulfone, polyether sulfone, etc.), fluorine resins (e.g., polytetrafluoroethylene, polyvinylidene fluoride, etc.), cellulose resins, polybenzimidazole resins, acrylic resins (e.g., polyacrylonitrile resins copolymerized with acrylic acid esters or methacrylic acid esters, modacrylic resins copolymerized with acrylonitrile and vinyl chloride or vinylidene chloride, etc.), etc., using known resins.

[0015] Note that these resins may be composed of either linear polymers or branched polymers, and the resin may be a block copolymer or a random copolymer. Also, the three-dimensional structure or the presence or absence of crystallinity of the resin is not particularly limited. Furthermore, a mixed resin in which a plurality of resins are mixed may also be used.

[0016] When flame retardancy is required for the surface material, it is preferable that the constituent fibers of the non-woven fabric contain a flame-retardant resin. Examples of such flame-retardant resins include, for example, modacrylic resin, vinylidene resin, polyvinyl chloride resin, polyvinylidene fluoride resin, novoloid resin, polyvinyl chloride resin, polyester resin copolymerized with a phosphorus compound, acrylic resin copolymerized with a halogen-containing monomer, aramid resin, and resin kneaded with a halogen-based, phosphorus-based or metal compound-based flame retardant.

[0017] The constituent fibers of the non-woven fabric may be composed of one type of resin or a plurality of types of resins. As fibers composed of a plurality of types of resins, for example, fibers generally called composite fibers, such as fibers having a core-sheath type, sea-island type, side-by-side type, orange type, bimetal type, etc. in the fiber cross-section can be adopted.

[0018] When the non-woven fabric contains heat-sealable fibers in the constituent fibers, it is preferable to impart strength and form stability to the non-woven fabric by heat-sealing the constituent fibers to each other. Such heat-sealable fibers may be fully heat-sealable fibers or partially heat-sealable fibers in the form of the above-described composite fibers. As a component that exhibits heat-sealability in the heat-sealable fibers, for example, a polyethylene resin or a low-melting-point polyester resin can be used.

[0019] The non-woven fabric according to the present invention includes, as constituent fibers, a first fiber (fine fiber) having the smallest average fiber diameter and a second fiber (thick fiber) having a larger average fiber diameter than the first fiber.

[0020] In order to be a surface material that prevents the back side from being seen through, the average fiber diameter of the fine fibers is preferably 15 μm or less, more preferably 13 μm or less. On the other hand, the lower limit value can be adjusted as appropriate, but 3 μm is realistic. Also, the average fiber diameter of the thick fibers is preferably 15 μm or more, more preferably 17 μm or more. On the other hand, the upper limit value can be adjusted as appropriate, but 70 μm is realistic. The average fiber diameter referred to here can be confirmed by the following method.

[0021] (How to determine the average fiber diameter) If the manufacturing process of the nonwoven fabric is known, the average fiber diameter of the fiber type (e.g., fine fibers or coarse fibers) used to manufacture the nonwoven fabric can be calculated from the fineness and specific gravity of that fiber type.

[0022] On the other hand, if the manufacturing process of the nonwoven fabric is unknown, it can be determined by the following method. Prepare the nonwoven fabric that makes up the surface material. In this case, the nonwoven fabric that makes up the surface material may be prepared by removing components other than the nonwoven fabric from the surface material. Then, cut out and collect a sample from the nonwoven fabric. Next, scanning microscope images (magnification: 500x or 1000x) are taken of the exposed cross-section of the collected sample. Then, 100 fibers of the fiber species for which the average fiber diameter is to be determined are randomly selected from the scanning microscope images. Next, the fiber diameter of each of the 100 selected fibers is determined. Note that fiber diameter refers to the diameter of a circle with the same area as the fiber cross-section captured in a scanning microscope image. Finally, the arithmetic mean of the determined fiber diameters is calculated and used as the average fiber diameter for the fiber species for which the average fiber diameter is to be determined.

[0023] The difference between the average fiber diameter of the fine fibers and the average fiber diameter of the thick fibers is adjusted as appropriate to create a surface material that is not easily visible through to the reverse side. This difference is preferably 1 μm or more, more preferably 2 μm or more, and most preferably 3 μm or more. On the other hand, the upper limit can be adjusted as appropriate, but 10 μm is preferred.

[0024] Furthermore, to prevent the reverse side from being more visible through the surface material, it is preferable that fine and thick fibers are mixed in the nonwoven fabric. Such a nonwoven fabric can be prepared by feeding a fiber group, which is made by mixing fine and thick fibers, into a carding machine and using the resulting fiber web.

[0025] When a nonwoven fabric contains crimpable fibers as its constituent fibers, its elasticity increases, resulting in superior conformability to molds, which is desirable. As such crimpable fibers, for example, crimpable fibers that have undergone crimping from latent crimpable fibers can be used.

[0026] The constituent fibers of the nonwoven fabric may include fibers with irregular cross-sections in addition to fibers with approximately circular or elliptical cross-sections. These irregular cross-sections may include fibers with hollow cross-sections, polygonal shapes such as triangles, alphabetical shapes such as Y-shapes, irregular shapes, multi-lobed shapes, symbolic shapes such as asterisks, or shapes formed by combining multiple such shapes. However, in order to effectively prevent the back side from being visible through the surface material, it is preferable that the cross-sectional shape of the fine and thick fibers be circular. Whether or not the cross-sectional shape of the fibers is circular can be confirmed by the following method.

[0027] (Method for determining whether the cross-sectional shape of a fiber is circular or not) If the manufacturing process for the nonwoven fabric is known, 100 fibers of the type of fiber used to manufacture the nonwoven fabric (e.g., fine fibers or thick fibers) are randomly selected. Scanning microscope images of the cross-section of each selected fiber are then taken. Next, the longest line segment A is drawn on the fiber cross-section captured in the scanning microscope image. At this time, all drawn line segments A are made to overlap on the fiber cross-section. The length A of the line segment A is also measured. Then, the longest line segment B that is perpendicular to the drawn line segment A and whose ends lie on the contour of the fiber cross-section is drawn on the scanning microscope image. The length B of this line segment B is also measured. In this case, if, for any of the 100 selected fibers, the entire drawn line segment B overlaps the fiber cross-section, and the value obtained by dividing length A by length B is between 1.0 and 2.0, then it is determined that the fiber cross-sectional shape of the fiber type being measured (e.g., fine fiber or thick fiber) is circular. Conversely, if, for any of the 100 selected fibers, the drawn line segment B has a portion that does not overlap with the fiber cross-section, or if the entire drawn line segment B overlaps with the fiber cross-section but the value obtained by dividing length A by length B is greater than 2.0, then it is determined that the cross-sectional shape of the fiber type being measured (e.g., fine fiber or thick fiber) is not circular.

[0028] On the other hand, if the manufacturing process of the surface material is unknown, it can be confirmed using the following method. First, prepare the nonwoven fabric that makes up the surface material. Alternatively, this can be done by removing components other than the nonwoven fabric from the surface material. Then, cut and collect a sample from the nonwoven fabric. Next, scanning microscope images (magnification: 500x or 1000x) are taken of the exposed cross-section of the collected sample. Then, from the scanned microscope images, 100 fibers of the target fiber type (e.g., fine fibers or thick fibers) that are visible from the fiber cross-section are randomly selected. Then, the longest line segment A is drawn on the fiber cross-section captured in the scanning microscope image. At this time, all drawn line segments A are made to overlap on the fiber cross-section. The length A of the line segment A is also measured. Furthermore, the longest line segment B, which is perpendicular to the drawn line segment A and whose ends lie on the contour of the fiber cross-section, is drawn on the fiber cross-section captured in the scanning microscope image. Then, the length B of the line segment B is measured. In this case, if, for any of the 100 selected fibers, the entire drawn line segment B overlaps the fiber cross-section, and the value obtained by dividing length A by length B is between 1.0 and 2.0, then it is determined that the fiber cross-sectional shape of the fiber type being measured (e.g., fine fiber or thick fiber) is circular. Conversely, if, for any of the 100 selected fibers, the drawn line segment B has a portion that does not overlap with the fiber cross-section, or if the entire drawn line segment B overlaps with the fiber cross-section but the value obtained by dividing length A by length B is greater than 2.0, then it is determined that the cross-sectional shape of the fiber type being measured (e.g., fine fiber or thick fiber) is not circular.

[0029] Furthermore, the constituent fibers of the nonwoven fabric may be dope-dyed fibers, such as fibers prepared by kneading in pigment or dyed fibers. In addition, a flame retardant may be supported on the constituent fibers of the nonwoven fabric by using a binder or the like.

[0030] The fiber length of the constituent fibers of the nonwoven fabric is adjusted as appropriate, but it can be short fibers cut to a specific fiber length in order to realize a surface material with good moldability, such as being heat-moldable. The fiber length is preferably 20 mm or more, more preferably 25 mm or more, and even more preferably 30 mm or more. On the other hand, if the fiber length exceeds 110 mm, it may become difficult to realize a surface material with good moldability, such as being heat-moldable, so it is preferably 110 mm or less, and more preferably 60 mm or less. Note that "fiber length" refers to the value measured in accordance with JIS L1015 (2010), 8.4.1c) direct method (Method C).

[0031] The nonwoven fabric according to the present invention contains metal oxide particles in both its constituent fine and coarse fibers. The type of metal oxide particles can be appropriately selected and used to create a surface material that prevents the back side from being visible. For example, titanium oxide particles can be used as the metal oxide particles.

[0032] The present invention is characterized in that the mass percentage of metal oxide particles contained in the fine fibers relative to the mass of the fine fibers (hereinafter sometimes referred to as Percentage A) is less than the mass percentage of metal oxide particles contained in the mass of the thick fibers (hereinafter sometimes referred to as Percentage B). As will be clear from the examples described later, the surface material of the present invention has this configuration, making it possible to realize a surface material that is less likely to show through to the other side.

[0033] Percentage A is adjusted to be less than percentage B, but percentage A can be less than 1.5 mass%, 1.0 mass% or less, 0.7 mass% or less, 0.5 mass% or less, or 0.3 mass% or less. The lower limit is adjusted as appropriate, but 0.1 mass% is preferred.

[0034] Furthermore, percentage B can be greater than 0.3 mass%, 0.5 mass% or more, 0.7 mass% or more, 1.0 mass% or more, and 1.5 mass% or more. The upper limit can be adjusted as appropriate, but 3 mass% is preferable.

[0035] The percentage of the total mass of the fiber that is comprised of metal oxide particles is determined by the following method.

[0036] (How to calculate mass percentage) If the manufacturing process of the nonwoven fabric is known, and the mass percentage of metal oxide particles contained in the fibers (e.g., fine fibers or coarse fibers) used to manufacture the nonwoven fabric is known, then that mass percentage shall be used as the mass percentage of metal oxide particles contained in the fibers relative to the mass of the fibers. On the other hand, if the manufacturing process of the surface material is unknown, it can be determined by the following method. First, several fibers of the target fiber type (fine or thick fibers) are collected from the nonwoven fabric. Next, the mass of the collected fibers is measured. Then, a test solution is prepared by dissolving the fibers and subjected to an ICP emission spectrometer (ICP-OES) to measure the type of metal oxide particles contained in the collected fibers and the total mass of metal oxide particles contained in the multiple collected fibers. Finally, the percentage of the total mass of metal oxide particles contained in the collected fibers relative to the total mass of the collected fibers is calculated and expressed as the percentage of the mass of metal oxide particles contained in the fibers relative to the total mass of the fibers.

[0037] Such fine or thick fibers containing metal oxide particles can be produced by mixing the metal oxide particles into a resin capable of forming fine or thick fibers, and then subjecting the resin to a known method for producing fibers, as described later.

[0038] The ratio of the mass of fine fibers to the mass of coarse fibers that make up the nonwoven fabric is adjusted as appropriate to create a surface material that prevents the back side from being seen through as much as possible. Specifically, it is preferable that the ratio of fine fibers to coarse fibers is 10%:90% to 90%:10%, and more preferably 30%:70% to 70%:30%.

[0039] Furthermore, the nonwoven fabric according to the present invention may also contain fibers that do not contain metal oxide particles (for example, fibers composed only of the resin described above without containing metal oxide particles). However, it is preferable that the nonwoven fabric consists only of fine fibers and thick fibers in order to have a surface material that is less transparent to the reverse side.

[0040] The constituent fibers of nonwoven fabrics can be obtained by known methods such as melt spinning, dry spinning, wet spinning, direct spinning (meltblown, spunbond, electrostatic spinning, etc.), methods for extracting fine fibers by removing one or more resin components from composite fibers, and methods for obtaining divided fibers by beating the fibers.

[0041] For example, nonwoven fabrics can be prepared using fiber webs obtained by a dry method in which the fibers are intertwined by feeding them to a carding device or air array device, or by using fiber webs obtained by a wet method in which the fibers are dispersed in a solvent, formed into a sheet, and intertwined. Alternatively, nonwoven fabrics can be prepared using fiber webs obtained by spinning and collecting fibers using a direct spinning method (such as the melt-blown method, spunbond method, electrostatic spinning method, or a method in which a spinning stock and a gas flow are discharged in parallel (for example, the method disclosed in Japanese Patent Publication No. 2009-287138)).

[0042] Furthermore, it is preferable that the constituent fibers of the nonwoven fabric are entangled and integrated with each other. As a method for entangling and integrating the constituent fibers, for example, a needle punch treatment or a water jet entanglement treatment can be applied to the fiber web prepared as described above.

[0043] Furthermore, the constituent fibers of the nonwoven fabric may be bonded together. If the fiber web contains a binder, the constituent fibers may be bonded together and integrated by the binder, for example, by subjecting it to a heat treatment. Alternatively, if the fiber web contains heat-fusible fibers, the constituent fibers may be bonded together and integrated by melting the heat-fusible fibers and then solidifying them.

[0044] The heat treatment method can be selected as appropriate, but for example, it can be a method of heating or heating and pressurizing with a roll, a method of subjecting to a heating device such as an oven dryer, far-infrared heater, dry heat dryer, or hot air dryer, or a method of heating the contained resin by irradiating it with infrared rays under no pressure.

[0045] The type of binder that can be used is selected as appropriate, but examples include polyolefins (such as modified polyolefins), ethylene vinyl alcohol copolymers, ethylene-acrylate copolymers such as ethylene-ethyl acrylate copolymers, various rubbers and their derivatives (such as styrene-butadiene rubber (SBR), fluororubber, urethane rubber, ethylene-propylene-diene rubber (EPDM)), cellulose derivatives (such as carboxymethylcellulose (CMC), hydroxyethylcellulose, hydroxypropylcellulose), polyvinyl alcohol (PVA), polyvinyl butyral (PVB), polyvinylpyrrolidone (PVP), epoxy resins, polyvinylidene fluoride (PVdF), vinylidene fluoride-hexafluoropropylene copolymer (PVdF-HFP), acrylic resins (such as acrylic ester resins and acrylonitrile styrene copolymer resins), and polyurethane resins. It is preferable that the binder contains an acrylic resin, as this can result in a surface material with excellent conformability during molding.

[0046] The basis weight of the binder included in the nonwoven fabric should be selected as appropriate, but a higher binder content may make it more difficult to achieve a surface material with good moldability, such as heat molding. Therefore, the binder basis weight should be 50 g / m². 2 Preferably, it is 30 g / m 2 Preferably, it is 10 g / m 2 Below (ideally 0g / m 2 It is preferable that it be the case.

[0047] In addition to the resins mentioned above, the binder may also contain additives such as flame retardants, fragrances, pigments, antibacterial agents, antifungal agents, photocatalytic particles, emulsifiers, dispersants, surfactants, and thickeners.

[0048] The composition of the nonwoven fabric, such as its basis weight and thickness, is not particularly limited and can be adjusted as appropriate. For example, the basis weight of the nonwoven fabric can range from 30 to 500 g / m². 2 It can be 50-300g / m 2 It can be 80-250g / m² 2It can be. Note that the basis weight refers to the mass per 1 m 2 on the surface (main surface) having the largest area.

[0049] Also, the thickness of the non-woven fabric can be 0.1 to 5 mm, can be 0.5 to 3 mm, and can be 0.8 to 1.9 mm. Note that in the present invention, the thickness refers to the length in the vertical direction when a compressive load of 20 g / cm 2 is applied to the main surface.

[0050] In addition, the non-woven fabric may be provided with a print composed of a pigment and a binder on one of its main surfaces. The mode of the print can be adjusted as appropriate, and it may be provided with a print on the entire surface of one of the main surfaces, or may be provided with a print so as to form a pattern on a part of one of the main surfaces.

[0051] Next, a method for manufacturing the surface material of the present invention will be described. Note that the description will be omitted for the points having the same items and configurations as described above. The method for manufacturing the surface material according to the present invention can be appropriately selected. As an example, (Step 1) A step of preparing thick fibers containing metal oxide particles at a percentage B, (Step 2) A step of preparing fine fibers having an average fiber diameter smaller than that of the thick fibers and containing metal oxide particles at a percentage A smaller than the percentage B, (Step 3) A step of preparing a fiber web in which the fine fibers and the thick fibers are mixed and carded, (Step 4) A step of preparing a non-woven fabric by subjecting the prepared fiber web to needle punching treatment to entangle and integrate the fine fibers and the thick fibers, A manufacturing method of a surface material including a non-woven fabric having the above can be adopted.

[0052] In the above-described method for manufacturing the surface material, various secondary processes such as a step of laminating other constituent members on the prepared non-woven fabric and a step of processing the shape by punching the non-woven fabric according to the use and usage mode may be provided. Further, a pressing process step for smoothing the surface, such as a resilient press treatment, may be provided for the prepared non-woven fabric. Further, a step of applying a print to the non-woven fabric may be provided.

[0053] The nonwoven fabric prepared in this manner can be used as a surface material on its own. Alternatively, it may be a surface material formed by laminating other components such as a porous body, film, or foam onto the nonwoven fabric. The lamination method can be selected as appropriate, but for example, methods such as lamination and integration by subjecting the fabric to needle punching or water entanglement treatment, lamination and integration by bonding with a binder, or lamination and integration by melting the heat-fusible fibers of the nonwoven fabric or the constituent resins of other components and then solidifying them can be employed.

[0054] Interior and exterior materials can be manufactured by bonding a substrate and a prepared surface material with an adhesive in between to form a laminate, and then subjecting the laminate to a heat molding means such as a heated mold. If the surface material is a nonwoven fabric prepared by needle punching from only one side, the main surface on the needle-punched side may face the substrate side, or the main surface on the opposite side may face the substrate side.

[0055] The type of base material and adhesive used will be adjusted as appropriate depending on the desired physical properties of the interior and exterior materials. For example, fabrics (nonwoven, woven, or knitted), films, or foams can be used as base materials. Furthermore, polymer isocyanate adhesives such as polyurethane resin can be used as adhesives.

[0056] In particular, when the adhesive is polyurethane resin, exposure to ultraviolet light can cause the isocyanate contained in the polyurethane resin, or the unreacted isocyanate remaining after being used to form the polyurethane resin, to turn brown. Therefore, if the adhesive on the back of the surface material of interior and exterior materials turns brown (i.e., the isocyanate or the polyurethane resin containing it turns brown), the back of the surface material becomes more visible, resulting in an inferior aesthetic appearance for the manufactured interior and exterior materials.

[0057] However, the surface material according to the present invention prevents the back side from being visible. Therefore, even when a laminate in which polyurethane resin is interposed between a base material and the surface material according to the present invention is molded, such as by heat molding, to produce interior and exterior materials, the manufactured interior and exterior materials are prevented from being visible on the back side, thus preventing them from being inferior in terms of design. [Examples]

[0058] The present invention will be specifically described below with reference to examples, but these examples are not intended to limit the scope of the present invention.

[0059] (Preparation of constituent fibers) The following types of fibers were prepared, each containing titanium dioxide particles with an average particle diameter of 210 nm and a fiber length of 51 mm. All of these fibers had a circular cross-sectional shape. Solution-dyed polyester fiber A: Average fiber diameter: 11.0 μm, Percentage of metal oxide particles contained in the fiber relative to the total fiber mass: 0.3% by mass Solution-dyed polyester fiber B1... Average fiber diameter: 14.3 μm, Mass percentage of metal oxide particles contained in the fiber relative to the total fiber mass: 0.3% by mass Solution-dyed polyester fiber B2... Average fiber diameter: 14.3 μm, Mass percentage of metal oxide particles contained in the fiber relative to the total fiber mass: 0.7% by mass Solution-dyed polyester fiber C1... Average fiber diameter: 17.5 μm, Mass percentage of metal oxide particles contained in the fiber relative to the total fiber mass: 0.3% by mass Solution-dyed polyester fiber C2... Average fiber diameter: 17.5 μm, Mass percentage of metal oxide particles contained in the fiber relative to the total fiber mass: 1.5% by mass

[0060] (Comparative Examples 1-5, Example 1) The fiber groups, blended to match the fiber composition shown in Table 1, were fed into a carding machine and opened to form a fiber web. Then, a needle density of 400 needles / m was applied from one side of the fiber web. 2 Needle punching was performed to prepare the nonwoven fabrics of Comparative Examples 1-5 and Example 1, respectively.

[0061] The nonwoven fabrics prepared as described above were used as surface materials. Each surface material (nonwoven fabric) was then subjected to the following evaluation method to evaluate the opacity index of the surface material, and the results, along with the composition of each surface material (nonwoven fabric), are summarized in Table 1.

[0062] In the following tables, the values ​​in parentheses indicate the type of solution-dyed polyester fiber, specifically the average fiber diameter (in μm) and the percentage of the fiber's mass that contains metal oxide particles (in mass%).

[0063] Furthermore, the total mass of metal oxide particles contained in the nonwoven fabric (unit: g / m²) 2 ) is the fiber mass (expressed in basis weight, unit: g / m²) that makes up the nonwoven fabric. 2 The total mass (unit: g / m²) of the surface material (nonwoven fabric) prepared in Example 1 can be calculated by multiplying this by the mass percentage (unit: mass%) of the metal oxide particles contained in the constituent fibers relative to the total mass of the constituent fibers. 2 ) can be calculated by calculating 120 × {(0.3 / 100) × (50 / 100) + (0.7 / 100) × (50 / 100)}.

[0064] (How to determine the opacity index of surface materials) The surface material (nonwoven fabric) was subjected to Method 8.2 B (instrumental method) of JIS L1923:2017 "Method for Evaluating the Transparency of Textile Products". The value obtained by this evaluation method was rounded up to the first decimal place to calculate the transparency index of the surface material. A higher value of the calculated transparency index indicates that the surface material is less transparent to the reverse side, while a lower value indicates that the surface material is more transparent to the reverse side.

[0065] [Table 1]

[0066] From the results of comparing Comparative Examples 1 and 2, the following finding 1 was obtained. (Finding 1) When the total mass of metal oxide particles contained in the nonwoven fabric was reduced, the opacity index of the surface material containing the nonwoven fabric decreased, making the back side more visible.

[0067] Furthermore, the following finding 2 was obtained from comparing Comparative Examples 3 and 4. (Finding 2) If the total mass of metal oxide particles contained in the nonwoven fabric is the same, the opacity index of the surface material comprising the nonwoven fabric did not change even if the constituent fibers included fine fibers. In other words, the transparency of the reverse side did not change.

[0068] Based on the findings 1-2 above, it was hypothesized that, as long as a surface material is prepared using a nonwoven fabric with a small total mass of metal oxide particles, the opacity index of the surface material will decrease, making the back side more easily visible, regardless of whether the nonwoven fabric contains fine fibers as constituent fibers.

[0069] However, contrary to the above assumption, a comparison of Comparative Example 5 and Example 1 revealed that, despite a decrease in the total mass of metal oxide particles contained in the nonwoven fabric, the surface material prepared in Example 1 showed a higher opacity index and was less transparent to the reverse side compared to the surface material prepared in Comparative Example 5.

[0070] From the above, The nonwoven fabric contains fine and coarse fibers that include metal oxide particles as its constituent fibers. and, The percentage of the total mass of the fine fibers that is comprised of metal oxide particles is less than the percentage of the total mass of the thick fibers that is comprised of metal oxide particles. It was found that a surface material comprising a nonwoven fabric having both of these configurations makes it difficult to see through to the other side, even when the total mass of metal oxide particles contained in the nonwoven fabric is reduced. Therefore, the surface material of the present invention provides interior and exterior materials in which the back side is not visible through the surface.

[0071] (Examples 2-4) The fiber groups, blended to match the fiber composition shown in Table 2, were fed into a carding machine and opened to form a fiber web. Then, a needle density of 400 needles / m was applied from one side of the fiber web. 2 The nonwoven fabrics of Examples 2 to 4 were prepared by needle punching.

[0072] The nonwoven fabrics prepared as described above were used as surface materials. The composition and physical properties of each surface material (nonwoven fabric) are summarized in Table 2. In addition, the results of Example 1 are also included in Table 2 for easier understanding.

[0073] [Table 2]

[0074] Examples 1 to 4 are surface materials comprising a nonwoven fabric having both of the above-described configurations. Therefore, even if the total mass of metal oxide particles contained in the nonwoven fabric is reduced due to the light weight of the nonwoven fabric, the surface material is less likely to show through to the other side. [Industrial applicability]

[0075] The surface material of the present invention can be suitably used for automotive applications such as ceilings, door sides, pillar garnishes, and rear packages; for interior applications such as partitions; and for building materials such as wall coverings.

Claims

1. A surface material comprising a nonwoven fabric, The nonwoven fabric comprises a first fiber having the smallest average fiber diameter and a second fiber having a larger average fiber diameter than the first fiber. The first fiber and the second fiber contain metal oxide particles. The mass percentage of the metal oxide particles contained in the first fiber relative to the mass of the first fiber is less than the mass percentage of the metal oxide particles contained in the second fiber relative to the mass of the second fiber. Surface material.

2. Both the first fiber and the second fiber have a circular cross-sectional shape. The surface material according to claim 1.

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