Base material of interior material for vehicle, method of manufacturing the same, and molded ceiling for vehicle

Abstract

To provide a base material of an interior material for a vehicle excellent in rigidity, moldability and sound absorbing property even if glass fiber is not used as a reinforcing layer.SOLUTION: The length direction of short fibers used for a base material 20 is dispersed in various directions from a vertical direction Wa to (d) on a plane including the vertical direction Wa of the base material 20, and a high density layer 20a is formed in a fiber body 35 itself of the base material 20, so that rigidity is secured and the base material 20 of the vehicular interior material having excellent sound absorbing performance is provided.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a base material for a vehicle interior material having excellent sound absorption and formability, a manufacturing method thereof, and a molded vehicle ceiling. Specifically, the present invention relates to a base material for a vehicle interior material such as a ceiling material, a rear package tray material, a door trim material, a floor insulator material, a trunk trim material, and a dash insulator material, a manufacturing method thereof, and a molded vehicle ceiling. [Background technology]

[0002] One example of a molded vehicle ceiling with excellent sound absorption properties is known, which includes a base layer made of reinforcing fibers made of glass fibers with a length of 10 to 80 mm and a fiber diameter of 10 to 20 μm and a polypropylene resin as a matrix fiber, with a polypropylene resin layer, a polyamide layer, and a polyethylene layer stacked in that order on the surface side of this base layer, with a skin layer further provided on the surface side and a nonwoven fabric on the back side (Patent Document 1).

[0003] Also known is a molded vehicle ceiling in which glass fiber layers are provided as reinforcing materials on both sides of a base layer, a decorative nonwoven fabric is provided on the front side, and an airtight layer is provided on the back side, and the base layer is made of inelastic crimped short fibers and heat-bondable composite short fibers arranged with the length directions of the fibers concentrated in the thickness direction Ta of the molded ceiling (Patent Document 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Registered Utility Model No. 3018995 [Patent Document 2] Japanese Patent Application Publication No. 2019-59273 Summary of the Invention [Problem to be solved by the invention]

[0005] As shown in Patent Documents 1 and 2, glass fibers used as reinforcing materials have an extremely excellent reinforcing effect and good stability of molded dimensions, and are therefore widely used as interior materials for vehicles, particularly as molded vehicle ceilings.

[0006] However, because glass fibers are used, they must be handled carefully to avoid being pierced by the glass fibers, which makes them inefficient to work with.Furthermore, products that use glass fibers as a reinforcing material have the disadvantage of being difficult to recycle.

[0007] For this reason, the present applicant has conducted extensive research into a substrate that has sufficient sound absorption properties, rigidity, and formability for use as a vehicle interior material, particularly a vehicle molded ceiling material, without using glass fibers as a reinforcing material. In particular, the present applicant has investigated a structure in which fibers are oriented approximately perpendicular to the sheet surface by folding a fiber web into a wave shape, as taught in Patent Document 2. As a result, in the structure disclosed in Patent Document 2, the length direction of the short fibers is concentrated in the vertical direction Wa of the substrate, so that while the structure exhibits high rigidity in the vertical direction Wa of the substrate, it lacks rigidity in other directions and formability varies depending on the molding direction, making it extremely difficult to eliminate glass fibers as a reinforcing material.

[0008] Therefore, the present invention has been made in consideration of the above-mentioned problems of the conventional technology, and aims to provide a base material for a vehicle interior material that has excellent rigidity and formability and excellent sound absorption properties even without using glass fiber as a reinforcing layer, a manufacturing method thereof, and a molded vehicle ceiling. [Means for solving the problem]

[0009] The present invention is characterized in that, without using glass fiber as a reinforcing material to maintain the rigidity and formability of the vehicle interior base material, the base material is devised so that the length directions of the short fibers used in the base material are evenly dispersed in various directions in a plane including the vertical direction Wa of the base material, and a high-density layer is formed in the fibrous body of the base material itself, thereby providing a base material for vehicle interiors that ensures rigidity and has excellent sound absorption properties, a manufacturing method thereof, and a molded vehicle ceiling.

[0010] The invention of claim 1 is a substrate for vehicle interior materials, which has a fibrous body formed by laminating webs having staple fibers, both of whose core and sheath portions are core-sheath composite staple fibers of a thermoplastic resin, and by arranging a rectangular original plate having a thickness direction Ta as the lamination direction of the webs and a longitudinal direction Tb and a width direction Tc perpendicular to the thickness direction Ta, such that the thickness direction Ta of the original plate is oriented in the left-right direction Wc of the substrate, the longitudinal direction Tb of the original plate is oriented in the up-down direction Wa of the substrate, and the width direction Tc of the original plate is oriented in the front-to-rear direction Wb of the substrate, and the length directions of the staple fibers of the fibrous body are evenly distributed and arranged from the up-down direction Wa to the front-to-rear direction Wb of the substrate, and by heating and pressurizing the upper surface side of the fibrous body, a high-density layer having a higher density than the remaining portions of the upper surface side is integrally formed in the upper surface side of the fibrous body.

[0011] The invention of claim 2 is characterized in that, in the base material of the vehicle interior material described in claim 1, the original plate is cut into strip-shaped divided members having a predetermined dimension in the longitudinal direction Tb, the thickness direction Ta of the original plate is set to the left-right direction Wc of the base material, and multiple divided members are lined up with the cut surfaces of the divided members as the upper and lower surfaces, and welded together to form the fibrous body.

[0012] The invention of claim 3 is characterized in that, in the base material of the vehicle interior material described in claim 1, the web has the core-sheath composite short fibers and mixed short fibers made of PET resin, the content of the core-sheath composite short fibers is 50% by weight to 100% by weight, and the content of the mixed short fibers is 0% by weight to 50% by weight.

[0013] The invention of claim 4 is characterized in that, in the base material of the vehicle interior material described in claim 3, when the distribution state of the short fibers in the length direction in the web is divided into ranges A up to 30° from the left-right direction Wc of the base material upward, B over 30° up to 60°, and C over 60° up to 90°, the proportions contained in A, B and C are all within the range of 20% to 40%.

[0014] The invention of claim 5 is characterized in that, in the base material of the vehicle interior material of claim 4, when A, B and C are further divided into A1 and A2, B into B1 and B2, and C into C1 and C2 within a range of 15°, the proportions contained in A1, A2, B1, B2, C1 and C2 are all within a range of 10% to 25%.

[0015] The invention of claim 6 is the base material of the vehicle interior material according to claim 1, wherein the high-density layer has a density of 65,000 g / m 3 ~500,000g / m 3 , basis weight: 130g / m 2 ~250g / m 2 , thickness: 0.5 mm to 2.0 mm, the ratio of the density of the high-density layer of the base material to the density of the layer other than the high-density layer is 1:0.15 to 1:0.7, and the base material has a basis weight of 400 g / m 2 ~1,500g / m 2 , and thickness: 2.0 mm to 40 mm.

[0016] The invention of claim 7 is characterized in that in a molded vehicle ceiling comprising a base material of a vehicle interior material described in any one of claims 1 to 6, the high-density layer of the base material faces the inside of the vehicle compartment, the side without the high-density layer faces the outside of the vehicle compartment, a skin layer is provided on the inside of the vehicle compartment side of the high-density layer, and a back layer having a non-air-permeable membrane layer is provided on the outside of the vehicle compartment side without the high-density layer.

[0017] The invention of claim 8 is a method for manufacturing a base material of a vehicle interior material according to any one of claims 1 to 6, comprising the steps of: entangling the staple fibers including the core-sheath type composite staple fibers to form the web; stacking a plurality of the webs in a thickness direction Ta of the web and heating and pressing the stacked webs to form the original plate in which the staple fibers are entangled; and cutting the original plate, in which the length directions of the staple fibers in the original plate are evenly distributed from the longitudinal direction Tb of the original plate to the width direction Tc of the original plate, in the thickness direction Ta of the original plate using a cutting tool to form pieces having a predetermined dimension in the longitudinal direction Tb of the original plate. a step of rotating the orientation of the first divided member by 90 degrees to form a second divided member in which the cut surfaces of the first divided member consist of an upper surface and a lower surface; and a step of heating the upper surface of one of the fibrous bodies in which the length direction of the short fibers of the second divided member is evenly dispersed from the vertical direction Wa of the second divided member to the front-to-back direction Wb of the second divided member and compressing the fibrous body from the vertical direction Wa of the base material to form the high-density layer on the upper surface side of the fibrous body while maintaining the other layer of the base material as a low-density layer.

[0018] The invention of claim 9 is characterized in that, in the method for manufacturing a base material of a vehicle interior material described in claim 8, in the process of heating the upper surface of the fibrous body and compressing the fibrous body from the vertical direction Wa of the fibrous body, the lower surface side of the fibrous body is cooled.

[0019] The invention of claim 10 is characterized in that, in the method for manufacturing a base material of a vehicle interior material described in claim 8, in the step of cutting into first divided members having the specified dimensions, the first divided members are cut into multiple strips of the same width to form multiple first divided members, each first divided member is turned 90 degrees to form the second divided members arranged so that the cut surfaces of the first divided members form the upper and lower surfaces, the multiple second divided members are lined up and contacted so that the upper and lower surfaces of the second divided members form a single plane at the same height to form the fibrous body, and adjacent second divided members are maintained in a state of contact, and the entire body is heated to form the fibrous body in which the short fibers of the fibrous body are entangled and welded.

[0020] The invention of claim 11 is characterized in that, in the method for manufacturing a substrate for a vehicle interior material according to claim 10, one cut surface of the fibrous body is heated at 180°C to 240°C, and is pressed and held at a predetermined thickness for 0.5 seconds to 30 seconds, to form the high-density layer having a thickness of 0.05 mm to 2.0 mm and a basis weight of 50 g / m2 to 300 g / m2 on the one cut surface side of the fibrous body.

[0021] In the present invention, directions are defined as follows. The longitudinal direction Tb, thickness direction Ta, and width direction Tc of the original sheet are defined as follows: As shown in FIG. 6(1), during the process of manufacturing the original sheet, the web is folded and stacked while flowing. The direction in which the web flows and is folded is called the longitudinal direction Tb, the direction perpendicular to the flow direction of the web is called the width direction Tc, and the direction in which the web is stacked is called the thickness direction Ta. These directions are shown in FIG. 3(A). In other words, the thickness direction Ta of the original sheet is the stacking direction of the web, and the longitudinal direction Tb and width direction Tc of the original sheet are directions perpendicular to the thickness direction Ta of the original sheet. On the other hand, in the case of a fibrous body (or substrate), the original sheet is rotated 90 degrees, so that, as shown in FIG. 3(B), the thickness direction Ta of the original sheet is the left-right direction Wc of the fibrous body, the longitudinal direction Tb of the original sheet is the up-down direction Wa of the fibrous body, and the width direction Tc of the original sheet is the front-rear direction Wb of the fibrous body.

[0022] In the present invention, the term "evenly distributed" in "the length directions of the short fibers of the fibrous body are evenly distributed from the vertical direction Wa of the substrate to the front-to-back direction Wb of the substrate" means that when the direction of the short fibers of the substrate is measured as a vector in a plane from one surface side of the left-to-right direction We of the substrate, and the range from the vertical direction Wa of the substrate to the front-to-back direction Wb of the substrate is divided into predetermined angle ranges, the length directions of the fibers are included in each predetermined angular range at a predetermined ratio, as expressed above. [Effects of the Invention]

[0023] According to the present invention, it is possible to obtain a base material for a vehicle interior material that has excellent sound absorption properties and excellent rigidity and formability, and a molded ceiling using the base material, without having the problems associated with the prior art that uses glass fiber as a reinforcing material.

[0024] Furthermore, according to the present invention, since the length direction of the short fibers of the substrate is evenly dispersed from the vertical direction Wa of the substrate to the front-to-back direction Wb of the substrate, compared to when the length direction of the short fibers of the substrate is concentrated and biased in the vertical direction Wa of the substrate, it is possible to obtain a product that has excellent sound absorption properties as well as excellent rigidity and formability. Furthermore, by forming a high-density layer on the fibrous body of the substrate itself, it is not necessary to integrate the high-density layer and the substrate by adhesive or the like, and high rigidity is obtained, so that the product has excellent shape retention whether it is molded into a three-dimensional shape of an interior material or in a flat plate state before molding. [Brief explanation of the drawings]

[0025] [Figure 1] 1 is a perspective view of a vehicle equipped with a vehicle molded ceiling according to an embodiment of the present invention. [Figure 2] 1 is a cross-sectional view schematically showing a cross section of a substrate of the present invention. [Figure 3] (A) is a photograph of the original plate taken from diagonally above, (B) is a photograph of the fibrous body taken from diagonally above, and (C) is a photograph of the substrate with a high-density layer taken from diagonally above. [Figure 4] (A) is a microscopic enlarged photograph of the A side of FIG. 3(B), and (B) is a microscopic enlarged photograph of the B side of FIG. 3(B). [Figure 5] 1 is a table showing the blending ratio of each fiber for examples of the present invention and comparative examples. [Figure 6] 1 illustrates an example of a method for manufacturing a substrate according to an embodiment of the present invention. [Figure 7] 4 illustrates another example of a method for manufacturing a substrate according to an embodiment of the present invention. [Figure 8] 10 illustrates yet another example of a method for manufacturing a substrate according to an embodiment of the present invention. [Figure 9] FIG. 2 is a schematic diagram for explaining the angle when measuring the length direction (vector) of short fibers of a substrate. [Figure 10] 10 is a graph showing the angular distribution measured in FIG. 9. [Figure 11] 1 is a graph showing sound absorption properties of Examples and Comparative Examples. DETAILED DESCRIPTION OF THE INVENTION

[0026] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings. It should be noted that the following description of the preferred embodiments is merely exemplary in nature.

[0027] FIG. 1 shows a vehicle 1 in which a substrate 20 of the present invention is applied to a vehicle molded ceiling 10. FIG. 2 is a cross-sectional view that schematically shows a cross section of the substrate 20 of the present invention. As shown in FIG. 1, the vehicle molded ceiling 10 is disposed on the interior side of the roof panel 2 of the vehicle 1 and includes a panel-shaped ceiling material main body 11. As shown in FIG. 2, the ceiling material main body 11 includes a skin layer 40 provided on the interior side of the substrate 20, and a back surface layer 50 provided on the roof panel 2 side of the substrate 20 (i.e., the exterior side of the vehicle). Note that FIG. 2 shows a cross section of a portion of the ceiling material main body 11 in an exaggerated manner for clarity.

[0028] As shown in FIG. 2, the substrate 20 has a high-density layer 20a on the interior side (upper surface) and a low-density layer 20b on the exterior side (lower surface). The skin layer 40 has, in order from the substrate 20 side toward the interior side of the vehicle, an adhesive layer 41 and a skin material 42. The adhesive layer 41 is made of a polyethylene resin or the like commonly used in vehicle molded ceilings 10, and the skin material 42 is, for example, a knitted polyurethane resin or the like. The back surface layer 50 has, for example, an air-impermeable film layer 51 and a back surface material 52, in order from the substrate 20 side toward the exterior side of the vehicle. The air-impermeable film layer 51 includes, for example, a polyethylene resin film 51a, an air-impermeable polyamide resin film 51b, and a polyethylene resin film 51c toward the exterior side of the vehicle. The back surface material 52 is, for example, a nonwoven fabric made of a spunbond material of PET resin (polyethylene terephthalate resin).

[0029] FIG. 3 is a photograph illustrating the substrate 20 of the present invention. FIG. 3(A) shows the substrate 20 in the form of a base plate 31, FIG. 3(B) shows the substrate 20 in the form of a fibrous body 35, and FIG. 3(C) shows the substrate 20 in the form of a fibrous body 35, the fibrous body 35 including a high-density layer 20a and a low-density layer 20b. FIG. 4(A) is a 300x magnification micrograph of the A-side of the fibrous body 35 in FIG. 3(B), and FIG. 4(B) is a 300x magnification micrograph of the B-side of the fibrous body 35 in FIG. 3(B). As shown in FIGS. 3 and 4, the substrate 20 is formed by melting the sheath portions of the core-sheath composite short fibers 25 to bond the core portions, and in some cases, further dispersing and bonding the mixed short fibers 27. The substrate 20 integrally includes a high-density layer 20a on the interior side of the vehicle and a low-density layer 20b on the exterior side of the vehicle.

[0030] The high-density layer 20a and the low-density layer 20b of the substrate 20 are fibrous bodies 35 made of the same material, and although there are portions where the boundary between the high-density layer 20a and the low-density layer 20b is unclear after molding, in order to clearly distinguish between the high-density layer 20a and the low-density layer 20b, in this embodiment, the high-density layer (portion) formed when one surface (upper surface) of the substrate 20 is heated and pressurized is referred to as the high-density layer 20a, and the other layer (portion) having a lower density than the high-density layer 20a is referred to as the low-density layer 20b. In particular, the high-density layer 20a mainly plays a role in ensuring the rigidity of the substrate, and the low-density layer 20b mainly plays a role in increasing the sound absorption properties.

[0031] (Length direction of short fibers of base material) The length direction of the short fibers of the substrate 20 will be described with reference to FIGS.

[0032] Fig. 3 is a photograph of a part of the substrate 20 of the present invention, and is a perspective view illustrating the original plate 31 and the fibrous body 35. Fig. 4 is a photograph of the surface of Fig. 3(B).

[0033] As shown in Figures 3 and 4, the substrate 20 has as its initial material an original plate 31 in which a web 30 containing core-sheath composite short fibers 25, both of whose core and sheath portions are made of PET resin (polyethylene terephthalate resin), and mixed short fibers 27 are laminated in the vertical direction Wa.

[0034] Fig. 3(A) is a photograph showing the state of the original plate 31 of the substrate 20. In Fig. 3(A), the up-down direction Wa is the thickness direction Ta of the original plate, the direction from the center of the front side to the rear left is the longitudinal direction Tb of the original plate 31, and the direction from the center of the front side to the rear right is the width direction Tc of the original plate 31. On the right side and left side, what appears to be multiple thin layers in the up-down direction Wa indicates that the web 30 is multilayered.

[0035] FIG. 3(B) is a photograph showing the state of the fibrous body 35 of the substrate 20. In FIG. 3(B), the original plate 31 of FIG. 3(A) is cut into strips of a predetermined size, rotated 90 degrees, and joined together, which is referred to as the fibrous body 35 in the present invention. As shown in FIG. 3(B), the fibrous body 35 of the substrate 20 has the longitudinal direction Tb of the original plate 31 as the up-down direction Wa of the fibrous body 35, the thickness direction Ta of the original plate 31 as the left-right direction Wc of the fibrous body 35, and the width direction Tc of the original plate 31 as the front-back direction Wb of the fibrous body 35. Hereinafter, when describing the length direction of the fibers of the substrate 20, this refers to the direction of the fibrous body 35, and is described as the up-down direction Wa, the front-back direction Wb, and the left-right direction Wc, while the original plate 31 is described as the longitudinal direction Tb, the width direction Tc, and the thickness direction Ta. On the right side (side A) of FIG. 3(B), many vertical lines are seen, which indicate that many webs 30 are lined up and stacked in the vertical direction.

[0036] Fig. 3(C) is a photograph showing the substrate 20 provided with a high-density layer 20a on the upper surface of the fibrous body 35 in Fig. 3(B). In Fig. 3(C), the high-density layer 20a can be seen on the upper surface of the fibrous body 35, and the low-density layer 20b can be seen on the lower surface (below) thereof. Note that a thin film-like substance can also be seen on the lower surface of the fibrous body 35, but this is simply a thin film-like substance that was crushed during compression and is not the high-density layer 20a.

[0037] FIG. 4(A) is a 300x magnification micrograph of surface A of FIG. 3(B) (one end surface of the fibrous body 35 in the front-to-back direction Wb). FIG. 4(B) is a 300x magnification micrograph of surface B of FIG. 3(B) (one end surface of the fibrous body 35 in the left-to-right direction Wc). In FIG. 4(A), the white vertical lines are the lines of the sheath-core composite short fibers 25, and the slight inclination of the fibers at the upper and lower ends is due to compression from the up-down direction Wa. In FIG. 3(B), the white lines are the sheath-core composite short fibers 25, and the black lines are the blending short fibers 27. This sample is prototyped with white and black lines to distinguish between the sheath-core composite short fibers 25 and the blending short fibers 27. In actual use, it is expected that the sheath-core composite short fibers 25 and the blending short fibers 27 will be similar white fibers. Judging from surfaces A and B, on surface A, the web 30 of the fibrous body 35 is composed of multiple fiber bundles aligned in the vertical direction Wa, aligned in the horizontal direction Wc, and bonded to each other. Furthermore, looking at surface B, the length direction of the short fibers is not limited to the vertical direction Wa, but is dispersed in any direction within surface B. The short fibers do not face in a single linear direction, but rather meander and extend in various directions, and the fibers are entangled with each other. In the present invention, the length direction of the fibers is measured as a vector in a plane, and any meandering or three-dimensional directions along the way are ignored.

[0038] In this way, in the present invention, the length directions of the short fibers of the fibrous body 35 of the base material 20 are evenly dispersed and oriented from the vertical direction Wa to the front-to-back direction Wb of the fibrous body 35, and are overlapped in the left-to-right direction We of the fibrous body. Therefore, the base material has high rigidity from the vertical direction Wa to the front-to-back direction Wb, which prevents deformation during molding, and moldability can be maintained, so that a base material 20 for vehicle interior materials can be obtained that is easy to mold, has high rigidity, and has excellent sound absorption properties.

[0039] In the present invention, "evenly dispersed and oriented" means that "when the vector in the length direction of the fiber is measured, the distribution state from the vertical direction Wa to the front-to-back direction Wb within one plane is dispersed evenly from the vertical direction Wa to the front-to-back direction Wb," and also means that "the fiber is not oriented with a biased concentration in either direction," which, expressed numerically, means that the distribution is 20% to 40% in all ranges of 0 to 30°, 31° to 60°, and 61° to 90°.

[0040] (Sheath-core composite short fiber 25) The sheath-core composite staple fibers 25 that are the material of the substrate 20 are general sheath-core composite staple fibers, and detailed description thereof will be omitted here. The sheath-core composite staple fibers 25 use PET (polyethylene terephthalate) fibers for both the core and sheath.

[0041] The fineness of the sheath-core composite short fibers 25 is preferably 1.5 dtex to 15 dtex, particularly 3.0 dtex to 8.0 dtex, because a low fineness makes handling difficult and reduces productivity, while a high fineness makes the fibers themselves thicker, reducing the air resistance and deteriorating sound absorption.

[0042] The fiber length of the sheath-core composite short fibers 25 is preferably in the range of 10 mm to 100 mm, particularly 20 mm to 80 mm, in order to improve processing stability in the manufacturing process of the substrate 20 for vehicle interior materials. Furthermore, it is preferable to configure the fibers to have mechanical crimps, etc., so that more minute cells can be formed.

[0043] The melting point of the sheath portion of the sheath-core composite staple fibers 25 is preferably 90°C to 180°C. In particular, if the melting point of the sheath portion of the sheath-core composite staple fibers 25 is too high, the fibers will have insufficient fluidity when heated and press-molded, preventing the high-density layer 20a from following the molding direction and resulting in poor moldability. Conversely, if the melting point of the sheath portion of the sheath-core composite staple fibers 25 is too low, the fibers will melt too much, increasing the possibility of large holes being formed in the substrate 20. Therefore, the melting point of the sheath portion of the sheath-core composite staple fibers 25 is preferably 90°C to 180°C. On the other hand, the melting point of the core portion of the sheath-core composite staple fibers 25 must be such that the core portion does not melt when heated and press-molded, and therefore is preferably 30°C or more higher than the melting point of the sheath portion of the sheath-core composite staple fibers 25. Specifically, for example, the core portion of the sheath-core composite staple fibers 25 is preferably a PET fiber having a melting point of 220°C to 270°C.

[0044] In this embodiment, the core portions of the sheath-core composite short fibers 25 are entangled with each other, and the sheath portions are melted and hardened to bond the core portions together. This allows the substrate 20 for vehicle interior materials to be easily and reliably molded into a three-dimensional shape, and the shape can be reliably maintained. Furthermore, the core portions of the sheath-core composite short fibers 25 exist as entangled fibers that constitute the substrate 20, retaining their fiber shape while being strongly bonded by the sheath fibers, which greatly helps to form more microscopic cells inside the substrate 20. As a result, a structure (approximately mesh-like structure) that can enhance the sound-absorbing performance of the substrate 20 can be easily formed.

[0045] (Short fiber for mixing 27) The sheath-core composite staple fibers 25 may be mixed with blending short fibers 27 similar to the sheath-core composite staple fibers 25. Replacing some of the sheath-core composite staple fibers 25 with general blending short fibers 27 can reduce costs. Even in this case, the blending short fibers 27 are preferably PET fibers, since they have good bondability and are preferable from the standpoint of recyclability if made of the same material as the sheath-core composite staple fibers 25. The fineness of the blending short fibers 27 is preferably in the range of 1.5 dtex to 15 dtex, particularly 3.0 dtex to 8.0 dtex, similar to the sheath-core composite staple fibers 25. The fiber length of the blending short fibers 27 is preferably in the range of 10 mm to 100 mm, particularly 20 mm to 80 mm. The melting point of the mixed short fibers 27, like the core portion of the core-sheath composite short fibers 25, is preferably 30°C higher than the melting point of the sheath portion of the core-sheath composite short fibers 25, specifically within the range of 220°C to 270°C, so that the mixed short fibers 27 do not melt when the sheath portion of the core-sheath composite short fibers 25 melts.

[0046] In addition, by using PET fibers for both the core-sheath composite short fibers 25 and the mixed short fibers 27, it becomes possible to easily mix the base material 20 of a used vehicle interior material as part of the material with the new material of the base material 20 of the vehicle interior material of this embodiment.

[0047] (proportion of each short fiber) The content of the core-sheath composite short fibers 25 contained in the entire web 30 is preferably 50% by weight to 100% by weight, more preferably 60% by weight to 90% by weight, and even more preferably 70% by weight to 85% by weight. If the content of the core-sheath composite short fibers 25 is less than 50% by weight, it becomes difficult to sufficiently maintain the shape stability of the substrate 20 of a vehicle interior material molded into a three-dimensional shape.

[0048] Furthermore, a portion of the sheath-core composite staple fibers 25 can be replaced with mixing staple fibers 27. In order for the staple fibers to fuse together, 50% by weight or more of the sheath portion of the sheath-core composite staple fibers 25 is required, and the maximum amount of the sheath-core composite staple fibers 25 that can be replaced with mixing staple fibers 27 is up to 50% by weight. Therefore, the content of mixing staple fibers 27 in the entire web 30 is preferably 0% to 50% by weight, more preferably 5% to 40% by weight. Since mixing staple fibers 27 can be obtained at a lower cost than sheath-core composite staple fibers 25, increasing the amount of mixing staple fibers 27 is effective in terms of cost. However, since the amount of sheath-core composite staple fibers 25 becomes relatively small and the sheath portion that fuses the staple fibers together becomes smaller, the amount of mixing staple fibers 27 can be set to an amount that does not result in insufficient welding strength or molding defects, taking into account the size and molding state of the substrate 20 of the vehicle interior material.

[0049] (High density layer 20a) The high-density layer 20a, a feature of this embodiment, is formed by using a core-sheath composite short fiber 25 as a substrate and applying heat and pressure to one side of the substrate to melt the sheath fibers. In other words, the high-density layer 20a is not formed by bonding a separate film material to the substrate. This eliminates the need to worry about adhesion to the substrate, and the high-density layer 20a can be manufactured integrally with the nonwoven fabric substrate, resulting in excellent productivity. In particular, since the high-density layer 20a and the substrate are made of the same material, it is possible to obtain a product that has good formability, increased strength, and excellent shape retention. Furthermore, since the high-density layer 20a is once formed and solidified, even if the entire product is heated to facilitate formability, the high-density layer 20a remains, resulting in a stable high-density layer 20a.

[0050] Furthermore, because the high-density layer 20a has a high density and high rigidity, the substrate 20 of the vehicle interior material can be easily molded into a three-dimensional shape without containing reinforcing members such as glass fiber, and has excellent deformation resistance after molding. The high-density layer 20a has a relatively high density, a low basis weight, and a thin thickness compared to the low-density layer 20b. Specifically, if the density of the high-density layer 20a is too high, the air permeability will increase, resulting in poor sound absorption in the high-frequency range and making molding difficult. If the density of the high-density layer 20a is too low, the rigidity of the substrate 20 as a vehicle interior material will be insufficient and moldability will be poor. Therefore, the density of the high-density layer 20a should be 65,000 g / m 3 ~500,000g / m 3 , especially 80,000 g / m 3 ~400,000g / m 3 , and even 100,000g / m 3 ~300,000g / m 3 It is preferable to set the following.

[0051] In the high-density layer 20a, the molten sheath portion closes some of the voids present in the core-sheath composite short fibers 25, reducing the air permeability and increasing the density, thereby making it possible to realize a base material 20 for vehicle interior materials that has better sound absorption performance, sound insulation performance, and rigidity.

[0052] If the thickness of this high-density layer 20a is too thick, it will have poor elongation and formability, and if it is too thin, it will have poor shape retention, so the thickness after molding is preferably 0.5 mm to 2.0 mm, particularly 0.7 mm to 1.5 mm. If it is less than 0.5 mm, not only will the high-density layer 20a be very prone to tearing, but it will also lack rigidity, resulting in poor formability and shape retention. Conversely, if it exceeds 2.0 mm, it will have insufficient fluidity when heated and press-molded, and the high-density layer 20a will not be able to follow the molding direction of the base material 20, which may result in poor formability.

[0053] The weight of the high density layer 20a is preferably 50 g / m 2 ~300g / m 2 , especially 100g / m 2 ~250g / m 2 50g / m 2If the weight per unit area of ​​the high-density layer 20a is less than 300 g / m, the thickness of the high-density layer 20a will be insufficient, resulting in thin portions and, in some cases, a portion where the layer itself does not exist. 2 If the value exceeds this, the sound absorption effect is likely to be impaired.

[0054] (Low density layer 20b) By leaving the low-density layer 20b other than the high-density layer 20a in the substrate 20, excellent sound absorption properties can be achieved. That is, the substrate 20 of the vehicle interior material can absorb noises such as engine noise, external noise, and road noise by the high-density layer 20a and the low-density layer 20b.

[0055] If the density of the low-density layer 20b is too high, the difference with the high-density layer 20a will be insufficient, resulting in excessive rigidity, and if it is too low, the sound absorption in the low-frequency range will be insufficient. 3 ~92,000g / m 3 , especially 10,000 g / m 3 ~70,000g / m 3 , and even 20,000 g / m 3 ~50,000g / m 3 It is preferable to set the following.

[0056] If the weight of the low-density layer 20b is too high, moldability will be poor, and if it is too low, sound absorption will be insufficient. 2 ~1,400g / m 2 , especially 200g / m 2 ~1,000g / m 2 , and even 250g / m 2 ~800g / m 2 It is preferable to set the following.

[0057] If the thickness of the low-density layer 20b is too thick, the high-density layer 20a will be relatively thin or the entire substrate 20 will be thick, making it difficult to mold and reducing shape retention, while if it is too thin, sound absorption properties will be unsatisfactory. Therefore, it is preferable that the thickness be 5 to 40 mm, particularly 7 mm to 30 mm, and even more preferably 7 mm to 20 mm.

[0058] If the density ratio between the high density layer 20a and the low density layer 20b is too high, the moldability and sound absorption properties will be insufficient, and if it is too low, the moldability and sound absorption properties will be poor. Therefore, it is preferable that the density ratio of the high density layer 20a:low density layer 20b be within the range of 1:0.15 to 1:0.7.

[0059] If the ratio of the basis weight of the high density layer 20a to the low density layer 20b is too high or too low, sound absorption properties and moldability will be deteriorated, so it is preferable to set it within the range of 1:1.5 to 1:5.0.

[0060] If the thickness ratio of the high density layer 20a to the low density layer 20b is too high, the high density layer 20a will be insufficient, and if it is too low, the low density layer 20b will be insufficient, so it is preferable that the ratio is within the range of 1:4 to 1:20.

[0061] (The entire base material for automotive interior materials) If the total basis weight of the substrate 20 including the high-density layer 20a and the low-density layer 20b is too low, the effects of sound absorption and sound insulation cannot be expected, and conversely, if it is too high, the bonding strength of the core portion of the core-sheath type composite short fiber 25 decreases. Therefore, the total basis weight of the substrate 20 including the high-density layer 20a is set to 400 g / m 2 ~1,500g / m 2 , especially 500g / m 2 ~1,400g / m 2 , and even 700g / m 2 ~1,300g / m 2 It is preferable to set the following.

[0062] If the overall density of the substrate 20 is too high, the rigidity becomes too strong and the formability becomes poor, and if it is too low, the rigidity becomes insufficient. 3 ~750,000g / m 3 , especially 30,000 g / m 3 ~600,000g / m 3 , and even 40,000 g / m 3 ~500,000g / m 3 It is preferable to set the following.

[0063] The overall thickness of the substrate 20 is preferably 2.0 mm to 40 mm, particularly 3.0 mm to 30 mm, and further preferably 4.0 mm to 20 mm. If the overall thickness is less than 2.0 mm, the substrate 20 will not be able to sufficiently ensure rigidity and shape retention. Furthermore, it will be impossible to form a large number of cells, and a sufficient sound absorption effect will not be achieved. Conversely, if the thickness exceeds 40 mm, the substrate 20 will be difficult to mold, making it impossible to reduce the weight and increasing costs.

[0064] (Vehicle ceiling molding 10) In the case of a molded vehicle ceiling 10 as an example of a product, if the basis weight of the molded vehicle ceiling 10 is too high, it will be heavy and cost will increase, and if it is too low, the effects of sound absorption and sound insulation cannot be expected. Therefore, 2 ~2,000g / m 2 , especially 800g / m 2 ~1,800g / m 2 , and even 900g / m 2 ~1,500g / m 2 It is preferable to set the following.

[0065] If the thickness of the vehicle molded ceiling 10 is too thick, it will be heavy and costly, and if it is too thin, sound absorption properties cannot be expected, so it is preferable that the thickness is 2.5 to 42 mm, particularly 5 to 30 mm, and even more preferably 8 to 20 mm.

[0066] A method for manufacturing the substrate 20 of the vehicle interior material of this embodiment will be described with reference to FIG. (1) As shown in FIG. 6(a), in a carding machine 110 having a carding machine 111 and a cross layer 112, core-sheath composite short fibers 25 (or short fibers further containing mixed short fibers 27) that will become the substrate 20 are entangled to form a web 30, and these webs 30 are stacked in the thickness direction Ta of the webs 30 to obtain a base plate 31 consisting of a laminate of webs 30. In this process, the length directions of the short fibers are distributed almost evenly in various directions from the longitudinal direction Tb to the width direction Tc of the web 30. These webs 30 are stacked in the thickness direction Ta of the webs 30 to obtain a base plate 31 consisting of a laminate of webs 30. For example, approximately 10 to 30 webs each having a thickness of 0.5 mm to 1.5 mm are stacked and heated and compressed to form a base plate 31 having a thickness of approximately 5 mm to 45 mm. In this state, the length directions of the short fibers are distributed almost evenly from the longitudinal direction Tb to the width direction Tc of the original plate 31.

[0067] (2) Next, as shown in Fig. 6(b), this raw plate 31 is heated and pressurized in a first heating and pressurizing device 120 to bond the sheath and core portions of the sheath-core composite short fibers 25 in the raw plate 31 and / or the mixed short fibers 27. The heating conditions vary depending on the material of the sheath-core composite short fibers 25, the thickness of the raw plate 31, the number of overlapping webs 30, etc., but are, for example, 110°C to 150°C for about 0.5 to 3 minutes.

[0068] In the original plate 31 in this state, as shown in Fig. 6(c), the length directions of the short fibers are distributed almost evenly in various directions from the longitudinal direction Tb to the width direction Tc of the original plate 31. On the paper surface of Fig. 6(c), the up-and-down direction is the thickness direction Ta, the sideways direction is the longitudinal direction Tb, and the direction from the front to the right rear is the width direction Tc.

[0069] (3) Then, as shown in Fig. 6(d), a cutting tool 130 such as a cutter having a blade in the thickness direction Ta of the original plate 31 is lowered from above onto the original plate 31 to divide it into strip-shaped members (first divided members 32) each consisting of an elongated rectangular parallelepiped having a fixed dimension in the longitudinal direction Tb of the original plate 31. The fixed dimension varies depending on the vehicle model and part to be used, the thickness of the first divided member 32, etc., but is set within a range of 5 mm to 30 mm, for example.

[0070] (4) Then, as shown in Figure 6(e), first divided member 32 is rotated 90 degrees as if rolling, so that the top and bottom surfaces 32a and 32b of first divided member 32 become the side surfaces 33b of second divided member 33, and the cut surfaces 32b of first divided member 32 become the top and bottom surfaces 33a and 33b of second divided member 33. After the 90-degree rotation in Figure 6(e), the horizontal direction on the paper is the thickness direction Ta, the vertical direction is the longitudinal direction Tb, and the direction from the front to the right rear is the width direction Tc.

[0071] (5) Next, as shown in Figure 6(f), a predetermined number of these second divided members 33 are lined up in a row to form a parallel member 34. The second divided members 33 of the parallel member 34 in Figure 6(f) are rotated 90 degrees relative to the orientation of the first divided members 32 in Figure 6(e), so that the longitudinal direction Tb of the original plate 31 corresponds to the up-down direction Wa of the parallel member 34, the width direction Tc corresponds to the front-back direction Wb, and the thickness direction Ta corresponds to the left-right direction Wc. Therefore, the length directions of the short fibers of the parallel member 34 are distributed almost evenly and evenly in various directions from the up-down direction Wa to the front-back direction Wb of the parallel member 34.

[0072] (6) As shown in FIG. 6(g), the parallel members 34 are heated and pressurized in a second heating and pressing device 122. Specifically, the parallel members 34 are placed in the second heating and pressing device 122 while being pressed from the left-right direction Wc by a pressing tool 124, and heated for a predetermined time to fuse the short fibers of the parallel members 34, thereby obtaining a fibrous body 35. The heating conditions vary depending on the material of the sheath-core composite short fibers 25 and the thickness of the fibrous body 35, but are, for example, 1110°C to 150°C for approximately 0.5 to 3 minutes. In particular, when the length direction of the short fibers of the fibrous body 35 is viewed as a vector, they are dispersed almost evenly throughout the fibrous body 35 from the up-down direction Wa to the front-back direction Wb. However, there are also many short fibers oriented in the left-right direction of the fibrous body 35. These short fibers are compressed in the left-right direction, which causes the short fibers to become well entangled with each other, resulting in a unified fibrous body 35.

[0073] (7) As shown in Figure 6(h), the fibrous body 35 is pressed between rollers 140. At this time, the upper heating roller 141 is heated by a heater (not shown) or the like, while the lower cooling roller 142 is cooled with cooling water (not shown) or the like while pressing. Due to this temperature difference, a high-density layer 20a is formed on the upper surface of the fibrous body 35 at a predetermined density and a predetermined thickness, and the layers from the middle to the lower part are stably and reliably maintained as low-density layers 20b in a state approximately equal to the low density of the web 30.

[0074] In the parallel members 34, the fibrous body 35 made of the parallel members 34, and the substrate 20 made of the fibrous body 35 obtained as described above, the thickness direction Ta of the original plate 31 is aligned with the left-right direction Wc of the substrate 20, the longitudinal direction Tb of the original plate 31 is aligned with the up-down direction Wa of the substrate 20, and the width direction Tc of the original plate 31 is aligned with the front-to-back direction Wb of the substrate 20.

[0075] In the above embodiment, an example of manufacturing the web 30 by the carding machine 110 has been shown, but the manufacturing method is not limited to this. For example, the method of forming the web 30 can be, for example, to form the web 30 consisting of fiber bundles by discharging staple fibers including the core-sheath composite staple fibers 25 by an air laying method, or to form the web 30 by entangling the fibers using a fiber spreader or a carding machine.

[0076] Another manufacturing method will be described below with reference to FIG. 7. Only the differences from FIG. 6 will be explained. In this example, the separate steps shown in FIGS. 6(d) and (e) are performed as a single process in FIG. 7(d). Specifically, while the original sheet 31 is conveyed on the first conveyor 161, it is cut into first divided members 32 of a predetermined size in the longitudinal direction Tb by a cutting tool 130. The first divided members 32 are conveyed on the first conveyor 161 as they pass through an inverting device 165, where they are rotated 90 degrees and become second divided members 33. A predetermined number of second divided members 33 are removed from the second conveyor 162, resulting in the production of parallel members 34 as shown in FIG. 7(e). Subsequently, the steps shown in FIGS. 7(f) and (g) are performed, similar to those shown in FIGS. 6(g) and (h), to produce a fibrous body 35.

[0077] Another manufacturing method will be described below with reference to FIG. 8. Only differences from FIG. 6 will be explained. In the manufacturing method of FIG. 8, for example, as shown in FIG. 8(a), multiple webs 30 are stacked, resulting in a significantly increased number of webs 30 compared to the usual number. Then, as shown in FIG. 8(b), the webs are heated at this thickness and pressed with a press 125 or the like to obtain an integrated base plate 31a as shown in FIG. 8(c). For example, the base plate 31a is 500 to 1,800 mm thick. Next, as shown in FIG. 8(d), a cutting tool 130 cuts the base plate 31a in the vertical direction Wa into short fibrous bodies 35a of a predetermined size in the longitudinal direction Tb. When viewed from a perspective view of the cut surface of the fibrous bodies 35a as shown in FIG. 8(e), the length of the short fibers is evenly distributed from the vertical direction Wa to the front-to-back direction Wb. Next, the cut fibrous body 35a is turned 90 degrees horizontally from the state shown in Figure 8(e) and enters the roller 140 from the left-right direction Wc of the fibrous body 35a, forming a high-density layer 20a on one surface (upper surface). In this manufacturing method, the fibrous body 35 can be obtained directly from the original plate 31 without manufacturing the first divided member 32 or the second divided member 33. Note that, because the heating and compression equipment is large-scale, this method is more suitable for small products such as door trims, tonneau boards, and trunk room trims than for large products such as a vehicle molded ceiling 10.

[0078] (Method of manufacturing a molded vehicle ceiling 10) The substrate 20 is manufactured by the above-mentioned method, the surface layer 40 and the back surface layer 50 are prepared, the surface layer 40 is placed on the high density layer 20a side of the substrate 20, and the back surface layer 50 is placed on the low density layer 20b side, and the substrate 20 is heated to make it easy to form, and then pressed in a mold for the vehicle roof 10 to manufacture the vehicle roof 10. A cold forming mold is used as the mold.

[0079] The heating temperature, heating time, mold clearance, etc. can be appropriately selected and set depending on the thickness of the substrate 20, the fibers of the nonwoven fabric, or the intended use, but it is preferable that the heating temperature be 150°C to 220°C, the mold clearance be 5 to 20 mm, and the heating time be 5 to 30 seconds.

[0080] Although the above description has been given of an example in which molding is performed using a cold press mold, the manufacturing method is not limited to this, and molding may also be performed using a hot press mold, for example.

[0081] (Manufacturing conditions for the substrate 20) The method of laminating a web 30 from core-sheath composite short fibers 25 (or a mixture of short fibers 27 for incorporation) to obtain a base plate 31 is similar to the manufacturing method and manufacturing conditions for a general base plate, and detailed explanation will be omitted here.

[0082] (Conditions for forming high density layer 20a) If the heating temperature for forming the high-density layer 20a is too low, the required high-density layer 20a will not be formed. Conversely, if it is too high, the film thickness will be too thick, resulting in poor elongation and poor formability. Therefore, the heating temperature of the heating press is preferably 150°C to 220°C, particularly 160°C to 200°C. When using a heating press, the clearance is preferably 5.0 to 20 mm, particularly 7.0 to 15 mm, and the heating time is preferably 5 to 30 seconds, particularly 8 to 25 seconds. If the material is passed between rollers with one side heated rather than using a press, the heating time is shorter, so a higher heating temperature is possible. If the material is passed between rollers with one side heated, the time is shorter, so a narrower roller gap is preferable. The clearance is preferably 0.3 to 10 mm, particularly 0.5 to 8 mm, and the linear speed is preferably 1 to 8 m / min, particularly 2 to 7 m / min. Whether passing between heated rollers or using a press mold, the unheated side must be cooled with a coolant or the like to maintain room temperature. By heating one side and cooling the other, it is possible to reliably ensure a density difference between the heated side and the unheated side, and to control not only the density and thickness of the high-density layer 20a, but also the basis weight and thickness of the low-density layer 20b. In particular, by controlling the heating temperature, heating time, pressure, pressure gap, etc., it is possible to adjust the thickness and strength of the high-density layer 20a while ensuring the basis weight of the low-density layer 20b, making it easy to adjust the properties according to the intended use, etc.

[0083] (Molding conditions for vehicle ceiling 10) To mold the plate-shaped substrate 20 into a predetermined shape (e.g., rectangular), the substrate 20 is heated in a heating furnace or the like to facilitate molding (deformation), and the heated substrate is then placed in a cold press mold of the predetermined shape for molding. In this case, it is preferable to cool the substrate 20 as quickly as possible after molding into the predetermined shape in the press mold so that the shape can be maintained. Therefore, cooling air may be blown from the surface of the press mold to cool the heated substrate 20 while molding. The heating temperature should be such that the plate-shaped substrate 20 is easily moldable. It is sufficient that the temperature is higher than the melting point of the sheath portion of the core-sheath composite short fibers 25, but it does not need to be very high. The heating temperature is preferably within a range of, for example, 150°C to 220°C, particularly 160°C to 200°C. The heating time should also be sufficient to achieve a moldable state, and is preferably within a range of 5 to 30 seconds, particularly 10 to 25 seconds, and even more preferably 15 to 20 seconds.

[0084] The mold clearance of the cold press mold can be appropriately selected and set depending on the thickness of the substrate 20, the fibers of the nonwoven fabric, the intended use, etc., but a practical range is 5.0 mm to 20 mm, and in particular, about 4.0 mm to 15 mm. Note that although the above describes an example of molding using a cold press mold, the manufacturing method is not limited to this, and molding may also be performed using a hot press mold, for example. [Example]

[0085] FIG. 5 is a table showing the blending ratio of each fiber for the examples of the present invention and the comparative examples. EXAMPLES The present invention will be specifically described below with reference to examples. The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[0086] Example 1 The core and sheath of the core and sheath of the sheath composite staple fiber 25 were made of PET resin staple fibers with a fineness of 6.6 dtex and a fiber length of 51 mm, with the core and sheath having a melting point of 240°C and 110°C, respectively. The blending staple fiber 27 was made of PET resin staple fibers with a melting point of 240°C, a fineness of 6.6 dtex, and a fiber length of 51 mm. The blending staple fibers were a mixture of 80% by weight of the sheath core composite staple fiber 25 and 20% by weight of the blending staple fiber 27, with a total basis weight of 600 g / m. 2 A carding machine 110 was used to prepare a base plate 31 made of a sheet as shown in FIG. 3(A). This base plate 31 was then processed to form a fibrous body 35 as shown in FIG. 3(B). One roller surface of this fibrous body 35 was then heated (heating temperature: approximately 220°C, heating time: 5 seconds) while the other was cooled to room temperature with cooling water. The fibrous body 35 was then passed through a roller gap of 0.5 mm at a linear speed of 7 m / min under pressure, forming a substrate 20 having a high-density layer 20a on the upper surface of the fibrous body 35 and a low-density layer 20b on the remaining portion, as shown in FIG. 3(C). The density, basis weight, thickness, density ratio, basis weight ratio, and thickness ratio of the substrate 20, high-density layer 20a, and low-density layer 20b at this time are shown in FIG. 5. It should be noted that the thickness of the high density layer 20a and the low density layer 20b is not constant, so the thickness is averaged over the entire area, but it may be averaged over the majority of the thickness.

[0087] The surface layer 40 was overlaid on the interior side of the high-density layer 20a, and the back surface layer 50 was overlaid on the exterior side of the low-density layer 20b, and the layers were heated to facilitate molding and pressed in a cold press mold shaped for the molded ceiling to produce the molded vehicle ceiling 10. The surface layer 40 was made of a polyethylene resin adhesive layer 41 with a thickness of 40 μm and a basis weight of 315 g / m from the substrate 20 side. 2 The back surface layer 50 is made of a non-breathable film layer 51 made of a polypropylene resin film having a thickness of 20 μm, a polyamide resin film having a thickness of 10 μm, and a polyethylene resin film having a thickness of 7 μm, and a basis weight of 12 g / m. 2 The backing material 52 is made of a PET resin spunbond nonwoven fabric.

[0088] Specifically, before being placed in the cold press mold, the substrate 20, the surface layer 40, and the back surface layer 50 are all heated in a heating furnace (heating temperature: approximately 200°C, heating time: 20 seconds) to soften them for easy molding. Then, they are pressed in a cold press mold with a gap of 10.5 mm to form them into the shape of the molded vehicle headliner 10. The molded vehicle headliner 10 obtained after molding has a basis weight of 1,000 g / m 2 The dimensions were 1,200mm x 1,600mm x total thickness (total thickness) of 10.5mm.

[0089] Example 2 In Example 2, only the differences from Example 1 will be described, and a description of the common parts will be omitted. Example 2 differs from Example 1 in the density, basis weight, thickness, density ratio, basis weight ratio, thickness ratio, etc. of the substrate 20, high-density layer 20a, and low-density layer 20b. These values ​​are shown in Figure 5. The manufacturing method differs in that a press machine was used instead of a roller to form the high-density layer 20a. The press machine maintained a pressure state with a clearance of 10 mm for 20 seconds. The surface of the upper mold of this press mold was heated to 200°C, and the lower mold was cooled with cooling water to maintain approximately room temperature.

[0090] Example 3 In Example 3, only the differences from Example 1 will be described, and a description of the common parts will be omitted. Example 3 differs from Example 1 in the density, basis weight, thickness, density ratio, basis weight ratio, thickness ratio, etc. of the substrate 20, high-density layer 20a, and low-density layer 20b. These values ​​are shown in Figure 5.

[0091] (Comparative Example 1) Polypropylene resin is mixed with 50% by weight of glass fiber with a fineness of 6.6 dtex and a fiber length of 51 mm at 50% by weight, and the weight is 705 g / m 2 A polyethylene resin film having a thickness of 40 μm and a basis weight of 315 g / m was applied to one surface of the resin sheet. 2 On the other surface, a 30 μm thick polypropylene resin film, a 20 μm thick polyamide resin film, and a weight of 15 g / m2 The PET resin spunbond nonwoven fabrics were layered, heated to facilitate molding, and pressed in a cold molding die to produce a molded vehicle ceiling 10. 2 A molded ceiling measuring 1,200mm x 1,600mm x 10.5mm thick (total thickness including all materials that make up the molded ceiling) was manufactured.

[0092] (Comparative Example 2) A base plate was prepared by laminating a web containing 80% by weight of PET resin staple fibers with a core and sheath of 4.4 dtex and 51 mm length, each having a melting point of 240°C at the core and 110°C at the sheath, and 20% by weight of PET resin staple fibers with a melting point of 240°C, a fineness of 6.6 dtex, and a fiber length of 51 mm. The base plate was folded in an accordion shape as shown in Figure 2 of JP 2019-59273 A, so that the length direction of the staple fibers in the base plate was the thickness direction (Ta). A fiber structure was produced by heating one side of the folded portion of the fiber structure to form a high-density layer. A skin layer was then layered on this high-density layer, and a back layer was then layered on the other side of the folded portion of the fiber structure. The resulting product was then heated to facilitate molding, and molded into a molded ceiling using a cold molding die.

[0093] The surface layer and back surface layer were the same as those used in Example 1. The basis weight of the fiber structure of Comparative Example 2 was 700 g / m 2 The moulded ceiling has a weight of 1,100g / m 2 The thickness of the molded ceiling was 10.5 mm.

[0094] (1) Measurement in the longitudinal direction of the fiber The fibrous body of Example 1 was cut in the vertical direction Wa to prepare a sample measuring 50 mm x 50 mm and 10 mm thick. From this sample, the direction in which the length direction of the short fibers of the fibrous body 35 points upward from the left-right direction Wc of the fibrous body 35 (i.e., vector) was defined as "θ" as shown in FIG. 9, and the number of fibers was counted in increments of θ = 15°. As a result, of the 3,000 fibers, 559 were at angles of 0° to 15°, 571 at angles of 16° to 30°, 566 at angles of 31° to 45°, 751 at angles of 46° to 60°, 467 at angles of 61° to 75°, and 486 at angles of 76° to 90°. The number of fibers was measured at 10 random locations using a nanofocus X-ray CT scanner manufactured by Rigaku Corporation and ExFact analysis software manufactured by Nippon Visual Science Co., Ltd. The average value of the 10 locations was used as the number of fibers.

[0095] The longitudinal proportion of short fibers in the fibrous body 35 is in the range of 20% to 45%, particularly 25% to 40%, when the longitudinal direction of the fibers is divided into three ranges in 30° increments, proving that the proportion is evenly distributed without bias or concentration in any particular direction. In particular, as shown in Figure 10, when the longitudinal direction is divided into six ranges in 15° increments, the proportion is in the range of 10% to 25%, particularly 13% to 24%, proving that the proportion is evenly distributed without bias or concentration in any particular direction.

[0096] (2) Sound absorption The sound absorption coefficient in the tube was measured for the example of the present invention and comparative examples 1 and 2. The results are shown in Fig. 10. The sound absorption coefficient in the tube was measured in accordance with JIS A 1405-2, with sound waves incident perpendicularly to the surface on the skin layer 40 side, and with an air gap of 0 mm on the back layer 50 side.

[0097] For the examples of the present invention and comparative examples 1 and 2, samples were prepared by cutting out a circle with a diameter of 29 mm. The normal incident sound absorption coefficient of these samples was measured. The normal incident sound absorption coefficient was measured according to JIS A 1405-2 (ISO 10534-2).

[0098] 11, there appears to be no significant difference in sound absorption properties when comparing Example 1 with Comparative Examples 1 and 2. These results show that, compared to Comparative Examples 1 and 2 which contain glass fiber as a reinforcing material, the present invention can provide sound absorption properties comparable to those containing glass fiber by adjusting the length direction of the short fibers used in the substrate 20, even without containing glass fiber.

[0099] Furthermore, looking at the average sound absorption coefficient from 500 Hz to 5,000 Hz, Example 1 of the present invention was 0.61, Comparative Example 1 was 0.49, and Comparative Example 2 was 0.59, with Example 1 showing the best result.

[0100] (3) Bending rigidity The size of sample S was 50 mm x 150 mm, the span was 100 mm, and the test speed was 50 mm / min. The bending rigidity was measured in accordance with JIS K 7171.

[0101] In Examples 1 to 3, the bending rigidity was 24 N, 16 N, and 10 N in the front-rear direction Wb, and 11 N, 8 N, and 5 N in the left-right direction Wc. On the other hand, in Comparative Examples 1 and 2, the bending rigidity was 15 N and 17 N in the front-rear direction Wb, and 11 N and 14 N in the left-right direction Wc. All of these values ​​were 5 N or more, which satisfied the bending rigidity requirements. This Example has the same level of rigidity as Comparative Examples 1 and 2, and therefore it was proven that it can be used as a vehicle interior material, particularly a vehicle molded ceiling 10, even if it does not contain glass fiber as a reinforcing material.

[0102] (4) Formability The expansion rate of the sample was measured as an indicator of formability. A number of circular stamps with a diameter of 50 mm were attached to the backside of a flat substrate, and the substrate was deep-drawn 30 mm in a 150 mm x 150 mm deep-drawing mold to create a recess on the front side of the substrate. After this deep-drawing, the length of the elliptical circle was measured to calculate the expansion rate. For example, if a diameter of 50 mm before forming expanded to 60 mm after forming, the expansion rate was calculated as 120%.

[0103] In Examples 1 to 3, the values ​​in the front-rear direction Wb were 170, 160, and 150, and the values ​​in the left-right direction Wc were 150, 142, and 135. On the other hand, in Comparative Examples 1 and 2, the values ​​in the front-rear direction Wb were 140 and 170, and the values ​​in the left-right direction Wc were 130 and 160. All of these values ​​were within the range of 130 to 200, and the moldability required for vehicle interior materials was achieved. [Industrial Applicability]

[0104] The present invention is applicable to base materials for vehicle interior materials such as ceiling materials, rear package tray materials, door trim materials, floor insulator materials, trunk trim materials, and dash insulator materials, manufacturing methods thereof, and molded vehicle ceilings. [Explanation of symbols]

[0105] 1 vehicle 10. Molded headliner for vehicle 20 Base material 20a high density layer 20b low density layer 25 Core-sheath composite short fiber 27 Short fibers for mixing 30 Web 31 Original Plate 32 First divided member 32b Cut surface 33 Second divided member 35 Fibrous body 40 Epidermal layer 50 Back layer 51 Non-breathable membrane layer

Claims

1. A substrate for a vehicle interior material, a fibrous body formed by laminating webs each having staple fibers containing core-sheath composite staple fibers of a thermoplastic resin in both the core portion and the sheath portion, and arranging a rectangular original plate having a thickness direction Ta as the lamination direction of the webs and a longitudinal direction Tb and a width direction Tc as directions perpendicular to the thickness direction Ta, the thickness direction Ta of the original plate being directed to the left-right direction Wc of the substrate, the longitudinal direction Tb of the original plate being directed to the up-down direction Wa of the substrate, and the width direction Tc of the original plate being directed to the front-rear direction Wb of the substrate; A substrate for a vehicle interior material, characterized in that the length direction of the short fibers of the fibrous body is evenly distributed and arranged from the vertical direction Wa of the substrate to the front-to-rear direction Wb of the substrate, and by heating and pressurizing the upper surface side of the fibrous body, a high-density layer which is higher in density than the remaining part of the upper surface side of the fibrous body is integrally formed.

2. The substrate of the vehicle interior material according to claim 1, The base material for a vehicle interior material is characterized in that the original plate is cut into rectangular divided members having a predetermined dimension in the longitudinal direction Tb, and the thickness direction Ta of the original plate is aligned with the left-right direction Wc of the base material, and the cut surfaces of the divided members are arranged on the upper and lower surfaces, and are welded together to form the fibrous body.

3. The substrate of the vehicle interior material according to claim 1, the web includes the core-sheath type composite staple fibers and mixed staple fibers made of a PET resin, The content of the core-sheath type composite short fiber is 50% by weight to 100% by weight, A base material for vehicle interior materials, characterized in that the content of the short fibers to be mixed in is 0 to 50% by weight.

4. The substrate of the vehicle interior material according to claim 3, A substrate for a vehicle interior material, characterized in that when the distribution state of the short fibers in the web in the length direction is divided into ranges A up to 30° from the left-right direction Wc of the substrate upward, B over 30° to 60°, and C over 60° to 90°, the proportions contained in A, B and C are all within the ranges of 20% to 40%.

5. The substrate of the vehicle interior material according to claim 4, When A, B, and C are further divided into A1 and A2, B into B1 and B2, and C into C1 and C2 within a range of 15°, the proportions of A1, A2, B1, B2, C1, and C2 are all within a range of 10% to 25%.

6. The substrate of the vehicle interior material according to claim 1, The high-density layer has a density of 65,000 g / m ３ ~500,000g / m ３ , basis weight: 130g / m ２ ~250g / m ２ , thickness: 0.5 mm to 2.0 mm; a ratio of the density of the high-density layer of the base material to the density of the layer other than the high-density layer is 1:0.15 to 1:0.7; The substrate has a basis weight of 400 g / m ２ ~1,500g / m ２ and a thickness of 2.0 mm to 40 mm.

7. A molded vehicle ceiling comprising the base material of the vehicle interior material according to any one of claims 1 to 6, A molded ceiling for a vehicle, characterized in that the high-density layer of the base material faces the inside of the vehicle compartment, the side without the high-density layer faces the outside of the vehicle compartment, a skin layer is provided on the inside of the vehicle compartment side of the high-density layer, and a back layer having a non-air-permeable membrane layer is provided on the outside of the vehicle compartment side without the high-density layer.

8. In the method for manufacturing a substrate of a vehicle interior material according to any one of claims 1 to 6, entanglement of the staple fibers, including the core-sheath composite staple fibers, to form the web; a step of stacking a plurality of the webs in a thickness direction Ta of the webs and heating and pressing the stacked webs to form the base plate in which the short fibers are entangled; cutting the raw plate, in which the length directions of the short fibers in the raw plate are evenly dispersed from the longitudinal direction Tb of the raw plate to the width direction Tc of the raw plate, in the thickness direction Ta of the raw plate using a cutting tool to process the raw plate into first divided members each having a predetermined dimension in the longitudinal direction Tb of the raw plate; rotating the first divided member by 90 degrees to form a second divided member having an upper surface and a lower surface as cut surfaces of the first divided member; a step of heating the upper surface of one of the fibrous bodies, in which the length direction of the short fibers of the second divided member is evenly dispersed from the vertical direction Wa of the second divided member to the front-rear direction Wb of the second divided member, and compressing the fibrous body from the vertical direction Wa of the base material, to form the high-density layer on the upper surface side of the fibrous body and maintain the other layer of the base material as a low-density layer; A method for manufacturing a substrate for a vehicle interior material, comprising:

9. 9. The method for manufacturing a substrate for a vehicle interior material according to claim 8, A method for manufacturing a base material for vehicle interior materials, characterized in that in the process of heating the upper surface of the fibrous body and compressing the fibrous body in the vertical direction Wa of the fibrous body, the lower surface side of the fibrous body is cooled.

10. 9. The method for manufacturing a substrate for a vehicle interior material according to claim 8, In the step of cutting into the first divided members having the predetermined dimensions, the first divided members are formed by cutting into a plurality of strips having the same width; The second divided members are formed by turning each of the first divided members by 90 degrees so that the cut surfaces of the first divided members are the upper and lower surfaces, The fibrous body is formed by arranging a plurality of the second divided members in contact with each other so that the upper surface and the lower surface of each of the second divided members are in a single plane at the same height; A method for manufacturing a base material for vehicle interior materials, characterized in that adjacent second divided members are maintained in a contacting state, and the entire body is heated to form the fibrous body by entangling and welding the short fibers of the fibrous body.

11. The method for manufacturing a substrate for a vehicle interior material according to claim 10, One cut surface of the fibrous body is heated at 180°C to 240°C, and is pressed and held at a predetermined thickness for 0.5 seconds to 30 seconds to form a fibrous body having a thickness of 0.05 mm to 2.0 mm and a basis weight of 50 g / m on one cut surface side of the fibrous body. ２ ~300g / m ２ 10. A method for manufacturing a substrate for a vehicle interior material, comprising forming the high-density layer comprising:

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