Surface material

Abstract

This invention relates to a surface material that can be heat-molded to prepare various interior and exterior materials. [Solution] The ease with which a nonwoven fabric bends when attempting to bend it so that one (or the other) main surface forms a straight, ridged portion can be evaluated by the average value of the bending stiffness in the longitudinal direction and the bending stiffness in the transverse direction of the nonwoven fabric, which are measured when the nonwoven fabric is bent in this manner. Furthermore, both average values ​​were 1.10 gf·cm². 2 A surface material with a nonwoven fabric thickness of less than / cm is a surface material that is highly flexible on both sides. Therefore, the surface material according to the present invention makes it easy to prepare interior and exterior materials in which wrinkle formation is prevented.

Description

[Technical Field]

[0001] This invention relates to a surface material that can be heat-molded to prepare various interior and exterior materials. [Background technology]

[0002] Conventionally, various interior and exterior materials (hereinafter collectively referred to as interior and exterior materials) have been prepared by heat-molding surface materials. Specifically, interior and exterior materials are prepared by subjecting surface materials to a heat-molding process in which heat or heat and pressure are applied using heating means such as heating plates or heating rollers in molds, thereby bending and deforming them into the desired three-dimensional shape.

[0003] As an example of such a surface material, Japanese Patent Application Publication No. 2023-88222 (Patent Document 1) discloses a surface material made of a nonwoven fabric having a print on one of its main surfaces. Patent Document 1 also discloses the finding that if a surface material has the property of being easily bent, such a surface material is prone to wrinkling during the heat molding process. Therefore, in the invention of Patent Document 1, the average value of the bending stiffness of the surface material in the longitudinal and transverse directions, measured when the surface material is bent so that one of its main surfaces forms a straight peak, is 0.83 gf·cm. 2 By making the diameter larger than / cm, a surface material with excellent heat-molding properties is provided. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2023-88222 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, even when a surface material according to the prior art disclosed in Patent Document 1 was subjected to a heat molding process to prepare interior and exterior materials, wrinkles sometimes still existed in the prepared interior and exterior materials. This problem was particularly likely to occur when the surface material was heat-molded in a way that resulted in a shape with sharp angles or large irregularities (for example, when the surface material was heat-molded using a mold to achieve deep drawing).

[0006] Upon investigating the reasons for this problem, the applicant found that the surface material in the prior art is hard and difficult to bend, and that when bent along shapes with sharp angles or large irregularities, wrinkles tend to form in the valleys at the bent points. As a result, when the surface material is heat-molded while wrinkles are present, wrinkles are present in the prepared interior and exterior materials.

[0007] The present invention aims to provide a surface material that facilitates the preparation of interior and exterior materials in which wrinkle formation is prevented. [Means for solving the problem]

[0008] The first invention is a surface material comprising a nonwoven fabric, The average value of the bending stiffness in the longitudinal direction and the bending stiffness in the transverse direction of the nonwoven fabric, measured when the nonwoven fabric is bent so that one main surface of the nonwoven fabric forms a straight, ridged portion, The average value of the bending stiffness in the longitudinal direction and the bending stiffness in the transverse direction of the nonwoven fabric, measured when the nonwoven fabric is bent so that the other main surface of the nonwoven fabric forms a straight, ridged portion, is: All values ​​are 1.10 gf·cm². 2 It is less than / cm. A surface material comprising the aforementioned nonwoven fabric. [Effects of the Invention]

[0009] As a result of their consideration, the applicant obtained the following findings. When attempting to bend a surface material such that one major surface forms a linear ridge portion, and / or when attempting to bend the other major surface such that it forms a linear ridge portion (hereinafter sometimes collectively referred to as the bending ease of the front and back surfaces), if a surface material with both inferior bending ease is subjected to a thermoforming process, the surface material will be subjected to heat and pressure while remaining unable to deform sufficiently. Therefore, supplying a surface material with such physical properties to a thermoforming process will cause wrinkles to occur in the interior and exterior finishing materials. Furthermore, the physical properties of the surface material are affected by the physical properties of the non-woven fabric that constitutes the surface material. That is, supplying a surface material with a non-woven fabric having inferior bending ease on both the front and back surfaces to a thermoforming process will cause wrinkles to occur in the interior and exterior finishing materials.

[0010] Furthermore, in addition to the above findings, the applicant of the present application The bending ease of the non-woven fabric when attempting to bend one major surface of the non-woven fabric so as to form a linear ridge portion can be evaluated by the average value of the bending rigidity value in the longitudinal direction and the bending rigidity value in the lateral direction of the non-woven fabric measured when the non-woven fabric is bent in such a manner. And similarly, The bending ease of the non-woven fabric when attempting to bend the other major surface of the non-woven fabric so as to form a linear ridge portion can be evaluated by the average value of the bending rigidity value in the longitudinal direction and the bending rigidity value in the lateral direction of the non-woven fabric measured when the non-woven fabric is bent in such a manner. The applicant has found the following.

[0011] Based on the above findings, a surface material provided with a non-woven fabric in which both of the above average values are less than 1.10 gf·cm 2 / cm is a surface material rich in bending ease on both the front and back surfaces. Therefore, it is easy to prepare interior and exterior finishing materials in which the occurrence of wrinkles is prevented using the surface material according to the present invention.

Embodiments 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] Because the surface material according to the present invention is a nonwoven fabric, it is easy to create a surface material that is highly flexible, prevents wrinkle formation, and is easy to prepare as an interior or exterior material.

[0014] The constituent fibers of nonwoven fabrics include, for example, polyolefin resins (e.g., polyethylene, polypropylene, polyolefin resins with a structure in which some hydrocarbons are replaced with nitrile groups or halogens such as fluorine or chlorine), polymethylpentene, styrene resins, polyvinyl alcohol resins, polyether resins (e.g., polyetheretherketone, polyacetal, modified polyphenylene ether, aromatic polyetherketone, etc.), polyester resins (e.g., polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polycarbonate, polyarylate, fully aromatic polyester resins, etc.), and polyimide resins. It can be constructed using known resins such as polyamide-imide resins, polyamide resins (e.g., aromatic polyamide resins, aromatic polyetheramide resins, nylon resins, etc.), resins having nitrile groups (e.g., polyacrylonitrile, etc.), urethane resins, epoxy resins, polysulfone resins (e.g., polysulfone, polyethersulfone, etc.), fluorine resins (e.g., polytetrafluoroethylene, polyvinylidene fluoride, etc.), cellulose resins, polybenzimidazole resins, and 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.).

[0015] These resins may consist of either linear or branched polymers, and may be block copolymers or random copolymers. Furthermore, there are no particular limitations on the three-dimensional structure or crystalline properties of the resins. In addition, mixed resins containing multiple resins are also acceptable.

[0016] When flame retardancy is required for the surface material, it is preferable that the constituent fibers of the nonwoven fabric contain a flame-retardant resin. Examples of such flame-retardant resins include modacrylic resin, vinylidene resin, polyvinyl chloride resin, polyvinylidene fluoride resin, novoroid resin, polyclar resin, polyester resin copolymerized with phosphorus compounds, acrylic resin copolymerized with halogen-containing monomers, aramid resin, and resins kneaded with halogen-based, phosphorus-based, or metal compound-based flame retardants. Alternatively, the fibers may be dyed fibers such as fibers prepared by kneading in pigments or dyed fibers. Furthermore, the flame retardant may be supported by using a binder or the like.

[0017] The constituent fibers may be composed of one type of resin or multiple types of resins. Fibers composed of multiple types of resins are generally referred to as composite fibers, and their cross-sections may take various forms, such as core-sheath type, sea-island type, side-by-side type, orange type, or bimetal type.

[0018] When a nonwoven fabric contains heat-fusible fibers as its constituent fibers, it is preferable to impart strength and dimensional stability to the nonwoven fabric by heat-fusing the constituent fibers together. Such heat-fusible fibers may be fully fusible heat-fusible fibers or partially fusible heat-fusible fibers in the form of composite fibers as described above. As the component (resin) that exhibits heat-fusibility in the heat-fusible fibers, for example, polyethylene resin or low-melting-point polyester resin can be used.

[0019] When a nonwoven fabric contains crimpable fibers, its elasticity increases, resulting in superior conformability to molds, which is desirable. As such crimpable fibers, for example, crimpable fibers that have exhibited crimping from latent crimpable fibers can be used.

[0020] These constituent fibers may include fibers with irregular cross-sections in addition to fibers with approximately circular or elliptical cross-sections. These irregular cross-section fibers may have cross-sections such as hollow shapes, polygonal shapes like triangles, alphabetic shapes like Y-shapes, irregular shapes, multi-lobed shapes, symbolic shapes like asterisks, or shapes formed by combining multiple such shapes.

[0021] The fineness of the constituent fibers of the nonwoven fabric can be adjusted as appropriate, but it is preferably 5 dtex or less, and more preferably 3 dtex or less, in order to realize a surface material that is easy to prepare for interior and exterior use while preventing wrinkle formation. On the other hand, the lower limit can be adjusted as appropriate, but it is practical to be 0.1 dtex or more.

[0022] Furthermore, the fiber length of the constituent fibers is adjusted as appropriate, but the short fibers can be cut to a specific fiber length in order to realize a surface material that makes it easy to prepare interior and exterior materials that prevent the occurrence of wrinkles. 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 that makes it easy to prepare interior and exterior materials that prevent the occurrence of wrinkles, 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).

[0023] The constituent fibers 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.

[0024] Nonwoven fabrics can be prepared, for example, by a dry method in which the fibers are entangled by feeding them to a carding device or air array device, or by a wet method in which the fibers are dispersed in a solvent and spun into a sheet and then entangled. Alternatively, they may be prepared by spinning 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 stream are discharged in parallel to each other (for example, the method disclosed in Japanese Patent Publication No. 2009-287138)), while simultaneously entangling and collecting the spun fibers.

[0025] Next, the constituent fibers can be entangled and / or integrated to prepare a nonwoven fabric. Examples of methods for entangling and / or integrating the constituent fibers include entanglement using needles or a water stream, and bonding or melting the constituent fibers together using a binder or adhesive fibers incorporated into the nonwoven fabric by subjecting it to heat treatment.

[0026] 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.

[0027] 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), polyvinylidene fluoride-hexafluoropropylene copolymer (PVdF-HFP), acrylic resins (such as acrylic acid ester resins and acrylonitrile styrene copolymer resins), and polyurethane resins. When the binder contains an acrylic resin, the nonwoven fabric containing the binder softens appropriately when heated and molded along the mold, resulting in a surface material that conforms well to the mold and has excellent heat-moldability, which is preferable.

[0028] 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 heat-moldability. 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.

[0029] 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.

[0030] The composition of the nonwoven fabric, such as its thickness and basis weight, is not particularly limited and can be adjusted as appropriate. The thickness of the nonwoven fabric can be 0.1-5 mm, 0.5-3 mm, or 0.8-1.9 mm. The basis weight of the nonwoven fabric can be, for example, 50-500 g / m².2 can be, 80 to 300 g / m 2 can be, 100 to 250 g / m 2 can be. In the present invention, the basis weight refers to the mass per 1 m 2 on the surface (main surface) having the largest area of the measurement object. Also, the thickness refers to the length in the vertical direction when a compressive load of 20 g / cm 2 is applied in the direction perpendicular to the main surface.

[0031] The non-woven fabric included in the surface material according to the present invention is When the non-woven fabric is bent so that one main surface of the non-woven fabric forms a linear ridge portion, the average value of the bending rigidity value in the warp direction and the bending rigidity value in the weft direction of the non-woven fabric, which is measured, and the other main surface of the non-woven fabric When the non-woven fabric is bent so as to form a linear ridge portion, the average value of the bending rigidity value in the warp direction and the bending rigidity value in the weft direction of the non-woven fabric, which is measured, are both 1.10 gf·cm 2 / cm or less.

[0032] In the present invention, the average value of the bending rigidity value in the warp direction and the bending rigidity value in the weft direction of the non-woven fabric, which is measured when the non-woven fabric is bent so that one main surface of the non-woven fabric forms a linear ridge portion, can be obtained by the following method. (Method for obtaining the average value of the bending rigidity value) (Step 1) Prepare a non-woven fabric constituting the surface material. At this time, the non-woven fabric constituting the surface material may be prepared by removing components other than the non-woven fabric from the surface material. (Step 2) From the prepared non-woven fabric, collect 4 samples having a square shape with a side of 10 cm and having two opposing sides parallel to the production direction thereof. Any of the samples has two opposing sides (two sides having the warp direction) parallel to the production direction of the non-woven fabric and two opposing sides (two sides having the weft direction) orthogonal to the warp direction. (Step 3) Place one of the collected samples into a pure bending test machine (Kato Tech Co., Ltd., KES-FB2). At this time, one main surface of the sample should be positioned facing the side where the peak portion will be formed when the sample is bent by the pure bending test machine. The sample should also be gripped by two chucks on the pure bending test machine, spaced 1 cm apart and 10 cm wide. At this time, the direction connecting the chucks by the shortest distance should be parallel to the two sides of the sample that have a vertical direction. (Step 4) The sample held by the two chucks is moved by moving one of the chucks, with a curvature K = 0 to 2.5 cm. -1 Within the range of constant velocity (deformation speed 0.5 cm) -1 The sample is bent at a rate of ( / sec). At this time, the sample held by the two chucks is bent along an arc with a radius equal to the distance between the chucks. The bending stiffness value measured while the sample is being bent is determined, and the maximum value of the bending stiffness value a1 (unit: gf·cm) is selected. 2 The value of the bending stiffness ( / cm) is determined. The maximum value a1 of the bending stiffness obtained in this way is the bending stiffness value in the longitudinal direction of the nonwoven fabric, measured when the nonwoven fabric is bent so that one main surface of the nonwoven fabric forms a straight peak. (Step 5) Another sample from the collected samples is subjected to the above-mentioned (Steps 3-4) to obtain the maximum value a2 (unit: gf·cm) of the bending stiffness measured while the sample is being bent. 2 The value (in cm) is calculated. When setting the sample on the pure bending test machine, the direction connecting the chucks along the shortest distance is parallel to the two sides of the sample that have a transverse direction. The maximum value a2 of the bending stiffness obtained in this way is the lateral bending stiffness value of the nonwoven fabric, measured when the nonwoven fabric is bent so that one of its main surfaces forms a straight, ridged portion. (Step 6) The average of the maximum value a1 and the maximum value a2 obtained as described above is calculated as the average of the bending stiffness value in the warp direction and the bending stiffness value in the weft direction of the nonwoven fabric, measured when the nonwoven fabric is bent so that one main surface of the nonwoven fabric forms a straight peak (unit: gf·cm). 2 Let's assume it's / cm.

[0033] Furthermore, if the manufacturing process and production direction of the object to be measured, such as nonwoven fabric, are unknown, the production direction of the object to be measured can be confirmed by the following method. (Method for confirming the production direction of the object being measured) (Step 1) Take six or so rectangular samples (long side length: longer than 10 cm, short side length: 10 cm) from the object to be measured, such that the long sides are 30° apart from each other in the direction parallel to the main surface of the object to be measured. (Step 2) Place one of the collected samples into a pure bending test machine (Kato Tech Co., Ltd., KES-FB2). At this time, one main surface of the sample should be positioned facing the side where the peak portion will be formed when the sample is bent by the pure bending test machine. The sample should also be gripped by two chucks on the pure bending test machine, spaced 1 cm apart and 10 cm wide. At this time, the direction of the shortest distance between the chucks should be parallel to the direction of the long side of the sample. (Step 3) The sample held by the two chucks is moved by moving one of the chucks, with curvature K = 0 to 2.5 cm -1 Within the range of constant velocity (deformation speed 0.5 cm) -1 The sample is bent at a rate of ( / sec). At this time, the sample held by the two chucks is bent along an arc with a radius equal to the distance between the chucks. The bending stiffness value measured while the sample is being bent is determined, and the maximum value of the bending stiffness value (unit: gf·cm) is then determined. 2 Calculate the value of ( / cm). (Step 4) The remaining sample collected is subjected to the steps described above (Steps 2-3) in the same manner, thereby obtaining the maximum value of the bending stiffness measured while the sample is being bent (unit: gf·cm). 2 Calculate each of the values ​​( / cm). The maximum values ​​of each bending stiffness obtained as described above are compared, and the sample with the highest maximum bending stiffness value is selected. Then, the direction parallel to the long side direction of the sample in the object being measured is determined to be the production direction of the object being measured.

[0034] Furthermore, the bending stiffness values ​​a3 in the longitudinal direction and a4 in the transverse direction of the nonwoven fabric, as defined in this invention, which are measured when the nonwoven fabric is bent so that the other main surface of the nonwoven fabric forms a straight ridge, are obtained in steps 3 to 5 of the above-described (Method for determining the average value of bending stiffness) by setting the other main surface of the sample toward the side where the ridge is formed when the sample is bent using a pure bending test machine, and performing a bending test. Then, the average of the maximum value a3 and the maximum value a4 obtained as described above is calculated as the average value of the bending stiffness values ​​in the longitudinal direction and the transverse direction of the nonwoven fabric, which are measured when the nonwoven fabric is bent so that one main surface of the nonwoven fabric forms a straight ridge (unit: gf·cm). 2 Let's assume it's / cm.

[0035] The nonwoven fabric according to the present invention has an average value of 1.10 gf·cm² obtained as described above. 2 The value is less than / cm. Surface materials with nonwoven fabrics possessing such physical properties are highly flexible on both sides. To facilitate the preparation of interior and exterior materials with better wrinkle prevention, the average values ​​of both sides of the nonwoven fabric of the surface material are both 1.05 gf·cm. 2 Preferably, it should be less than or equal to 1.02 gf·cm. 2 Preferably less than / cm, and 0.86 gf·cm 2 It is more preferable that the value be less than or equal to / cm. The lower limit can be adjusted as appropriate, but 0.1gf·cm is preferable. 2 Preferably, it should be 0.3 gf·cm or more, and 0.3 gf·cm 2 It is more preferable to be 0.53 gf·cm or more, and 0.53 gf·cm 2 A value of / cm or greater is most preferable.

[0036] Furthermore, the nonwoven fabric may have a print made of pigment and binder on one of its main surfaces. The manner of the print can be adjusted as appropriate, but the print may cover the entire surface of one of the main surfaces of the nonwoven fabric, or it may be printed to form a pattern on only a portion of the main surface.

[0037] For example, a nonwoven fabric with a print on one main surface can be prepared by applying a print solution, in which a pigment and binder are dispersed in a dispersion medium, to one main surface using a spray or gravure roll, either as is or in a foamed state. Alternatively, a nonwoven fabric with a print on one main surface can be prepared by impregnating one main surface with the print solution.

[0038] Nonwoven fabric can be used as a surface material on its own. Alternatively, other components such as porous materials, films, or foams may be laminated onto the surface material. The lamination method can be selected as appropriate, but methods such as lamination and integration by subjecting the material to fiber entanglement treatment such as needle punching or water flow entanglement, lamination and integration by bonding with a binder, or lamination and integration by melting the adhesive fibers of the nonwoven fabric or the adhesive components of other components and then solidifying them can be employed.

[0039] The surface material can be subjected to a heat molding process, such as directly into a heated mold, to prepare the interior and exterior materials. However, it may also be subjected to various secondary processes, such as punching out shapes according to the application and usage, or adjusting various physical properties such as thickness and surface smoothness through processes like reliable press treatment, before being subjected to the thermoforming process.

[0040] Next, the method for manufacturing the surface material of the present invention will be described. Note that explanations of points that are the same as those described above will be omitted. The method for manufacturing the surface material according to the present invention can be appropriately selected, but as an example, (Step 1) A process in which fibers are fed into a carding machine, opened, and a fiber web is formed. (Step 2) A step in which the fiber web is made less susceptible to shrinkage in the transverse direction perpendicular to its production direction, and the fiber web is heated while in that state. (Step 3) A step to prepare a nonwoven fabric by cooling the heated fiber web in the same state. A method for manufacturing a surface material comprising a nonwoven fabric can be employed. The applicant of this application has found that by using the manufacturing method described above, both average values ​​defined in this invention are 1.10 gf·cm³.2 We discovered that it is possible to prepare a nonwoven fabric with physical properties of less than / cm.

[0041] (Step 2) will be explained. The method for making the fiber web less susceptible to shrinkage in the transverse direction perpendicular to its production direction can be adjusted as appropriate. For example, methods include fixing both ends of the fiber web on the transverse side perpendicular to the production direction with pins or clips, sandwiching the fiber web between two parallel flat plates or meshes, or maintaining tension in the transverse direction of the fiber web by pulling it in the transverse direction perpendicular to its production direction.

[0042] Next, the fiber web is heated in that state. The lower limit of the heating temperature is adjusted as appropriate, but it is preferable to set the heating temperature to be equal to or higher than the glass transition temperature of the resin with the lowest glass transition temperature among the resins that make up the fibers of the fiber web. Note that the glass transition temperature in this invention refers to the midpoint glass transition temperature (Tmg) read from the DSC curve drawn in accordance with JIS K7121 (1987). Furthermore, the upper limit of the heating temperature is adjusted as appropriate to prevent the components constituting the surface material from melting and to prevent their functions from being unintentionally reduced.

[0043] The fiber web can then be heated using the heat treatment method described above. In this process, the thickness of the fiber web may be adjusted by applying pressure simultaneously with heating the fiber web. The method for doing so can be adjusted as appropriate, but one example is to place the fiber web between heated rolls with a prepared gap.

[0044] (Step 3) will be explained. The method for cooling the heated fiber web while maintaining a state where it is less likely to shrink in the transverse direction perpendicular to its production direction can be adjusted as appropriate. Methods such as air cooling at room temperature or cooling using a cooling device can be employed.

[0045] By going through the above steps, both average values ​​as defined by this invention will be 1.10 gf·cm. 2 By preparing a nonwoven fabric with physical properties of less than / cm, a surface material with excellent flexibility on both sides can be provided. [Examples]

[0046] 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.

[0047] (Preparing the fiber web) Solution-dyed polyester fibers (fineness: 3.3 dtex, fiber length: 38 mm, melting point: 250°C, glass transition temperature: 70°C) were fed into a carding machine and opened to form a fiber web. Then, a needle density of 400 fibers / m was applied from one main surface side of the fiber web. 2 Needle punching was performed to prepare the needle-punched web. Then, a square-shaped sample (length in the vertical direction: 20 cm, length in the horizontal direction: 20 cm) was taken from the needle-punched web. At this time, five samples were taken from the needle-punched web so that the vertical direction was parallel to the production direction of the needle-punched web.

[0048] (Comparative Example 1) The sample was placed between heated rolls (gap spacing: 0.4 mm, roll heating temperature: 165°C) while in a free state, and the thickness was adjusted while heating to prepare a nonwoven fabric. The nonwoven fabric, which had been heat-treated in this manner, was used as the surface material.

[0049] (Example 1) The sample was fixed by pinning both ends on the lateral side perpendicular to the production direction, thereby making it difficult for the sample to shrink laterally. Then, while maintaining that state, the sample was placed between heated rolls (gap spacing: 0.4 mm, roll heating temperature: 165°C) to heat it and adjust its thickness, thereby preparing a nonwoven fabric. The nonwoven fabric, which had been heat-treated in this manner, was used as the surface material.

[0050] (Example 2) By applying tension to the sample in a lateral direction perpendicular to its production direction, the sample was made less susceptible to lateral contraction than in Example 1. Then, while maintaining that state, the sample was placed between heated rolls (gap spacing: 0.4 mm, roll heating temperature: 165°C) to heat it and adjust its thickness, thereby preparing a nonwoven fabric. The nonwoven fabric, which had been heat-treated in this manner, was used as the surface material.

[0051] (Example 3) The sample was pulled with a stronger force in the lateral direction perpendicular to its production direction, making it less susceptible to lateral contraction than in Example 2. Then, while maintaining that state, the sample was placed between heated rolls (gap spacing: 0.4 mm, roll heating temperature: 165°C) to heat it and adjust its thickness, thereby preparing a nonwoven fabric. The nonwoven fabric, which had been heat-treated in this manner, was used as the surface material.

[0052] (Example 4) The sample was pulled with a stronger force in the lateral direction perpendicular to its production direction, making it less susceptible to lateral contraction than in Example 3. Then, the sample was placed between heated rolls (gap spacing: 0.4 mm, roll heating temperature: 165°C) in its original state to heat it and adjust its thickness, thereby preparing a nonwoven fabric. The nonwoven fabric, which had been heat-treated in this manner, was used as the surface material.

[0053] Each surface material (nonwoven fabric) was subjected to the following evaluation method to determine whether or not it was a surface material with good heat-moldability. (Evaluation of wrinkle formation) (Step 1) Place the surface material on a smooth board. (Step 2) With the side of the sample C in contact with the smooth plate, the side of the sample A is lifted from the smooth plate and the sample is folded so that a perpendicular valley is formed between the two opposing sides (side A and side C) that are parallel to the vertical direction on all four sides of the surface material. At this time, the folded sample will have a straight valley forming a 90° angle, resulting in a shape resembling the letter "」". A straight peak will be formed on the main surface opposite to the main surface where the valley is formed. (Step 3) Visually inspect the shape of the valley portion in the folded sample as described in (Step 2). Then, the number of wrinkles observed visually in the valleys was used as a criterion to evaluate whether the surface material was prone to wrinkling in bent areas. A smaller number of wrinkles indicates that the surface material is easier to prepare for interior and exterior applications where wrinkle formation is prevented. ×: Five or more wrinkles were present, each longer than 0 cm but less than or equal to 5 cm in length. Additionally, wrinkles longer than 5 cm were present in the valleys. ○: 1 to 4 wrinkles were present, each longer than 0 cm but less than 5 cm in length. No wrinkles longer than 5 cm were present in the valleys. ◎: No wrinkles longer than 0 cm but less than 5 cm were observed. Furthermore, no wrinkles longer than 5 cm were observed in the valleys.

[0054] Table 1 summarizes the physical properties of the surface materials (nonwoven fabrics) produced in the comparative examples and examples.

[0055] [Table 1]

[0056] From the results above, it was found that the surface material (nonwoven fabric) of Comparative Example 1 was prone to wrinkles at the bent points. Therefore, the interior and exterior materials with steep angles prepared using this surface material (nonwoven fabric) exhibited the most wrinkles. Furthermore, the average value of the bending stiffness of the surface material (nonwoven fabric) in the longitudinal direction and the bending stiffness of the surface material (nonwoven fabric) in the transverse direction, measured when the surface material (nonwoven fabric) of Comparative Example 1 is bent so that one main surface forms a straight peak, The average value of the bending stiffness of the surface material (nonwoven fabric) in the longitudinal direction and the bending stiffness in the transverse direction, measured when the surface material (nonwoven fabric) is bent so that the other main surface forms a straight, ridged portion, is: All values ​​are 1.10 gf·cm². 2 It was not less than / cm.

[0057] In contrast, the surface material of the embodiment according to the present invention was less prone to wrinkles at the bent portion. Therefore, the interior and exterior materials with steep angles prepared using this surface material (nonwoven fabric) showed less wrinkle formation than the interior and exterior materials prepared in Comparative Example 1. Furthermore, the average value of the bending stiffness of the surface material (nonwoven fabric) in the longitudinal direction and the bending stiffness of the surface material (nonwoven fabric) in the transverse direction, measured when the surface material (nonwoven fabric) in Examples 1 to 4 is bent so that one main surface forms a straight peak, The average value of the bending stiffness of the surface material (nonwoven fabric) in the longitudinal direction and the bending stiffness in the transverse direction, measured when the surface material (nonwoven fabric) is bent so that the other main surface forms a straight, ridged portion, is: All values ​​are 1.10 gf·cm². 2 It was less than / cm.

[0058] From the above, the surface material according to the present invention facilitates the preparation of interior and exterior materials in which wrinkle formation is prevented. [Industrial applicability]

[0059] 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

[Claim 1] A surface material comprising a nonwoven fabric, The average value of the bending stiffness in the longitudinal direction and the bending stiffness in the transverse direction of the nonwoven fabric, measured when the nonwoven fabric is bent so that one main surface of the nonwoven fabric forms a straight, ridged portion, The average value of the bending stiffness in the longitudinal direction and the bending stiffness in the transverse direction of the nonwoven fabric, measured when the nonwoven fabric is bent so that the other main surface of the nonwoven fabric forms a straight, ridged portion, is: All values ​​are 1.10 gf·cm. ２ / cm is less than A surface material comprising the aforementioned nonwoven fabric.

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