JP4213291B2 - Composite material, synthetic sleeper using the composite material, and method for producing composite material - Google Patents

Description

【００４７】
上記表１から、本発明の複合材料が、曲げ強度に優れ、層間剥離の問題もない優れた物性を示すことがよくわかる。
【００４８】
【発明の効果】
本発明にかかる複合材料は、以上のように構成されているので、より曲げ強度の向上が望めるとともに、長期的にみても層間の接着性に優れたものとなる。
したがって、合成枕木等に使用した場合、耐久性が向上するとともに、安全性も高まる。
【００４９】
また、本発明にかかる複合材料の製造方法は、上記複合材料を連続的生産性よく製造することができる。
【図面の簡単な説明】
【図１】本発明にかかる複合材料の１つの実施の形態をその長手方向の垂直面で切断した断面図である。
【図２】本発明にかかる複合材料の製造方法に使用する製造装置の１例を模式的にあらわす模式図である。
【符号の説明】
１ 複合材料
１１ 第１層（表面層）
１２ 第２層（中間層）
１３ 第３層（芯層）
３ 成形用型（成形用通路）
６２ 発泡性樹脂液
８２〜８４ 小長繊維原料群[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a composite material and a synthetic sleeper using the composite material.
[0002]
[Prior art]
Fiber-reinforced composite materials (thermosetting foamed resin molded products) that are very similar in appearance to natural wood and that have physical properties equivalent to or better than natural wood are building materials, structural members, sleepers, and waterboards It is used as a structure.
[0003]
As this type of composite material, a composite material that has been proposed to improve compressive strength and nailing performance by making a sandwich structure in which a core layer having excellent compressive strength is sandwiched between surface layers has already been proposed (Japanese Patent Laid-Open No. Hei 5-). 138797).
[0004]
That is, in this composite material, the reinforcing fibers are aligned substantially parallel to the longitudinal direction on the surface of a lightweight and high compressive strength core layer made of a thermosetting resin foam in which 50% by weight or less filler is dispersed. The surface layer is made of a thermosetting resin foam that is lined up and dispersed in a lightweight, rigid, and high-strength and tensile-strength layer. It is excellent in strength and can say nails like wood.
[0005]
However, in the case of this composite material, there is a clear interface between the core layer and the surface layer, and due to the difference in elastic modulus between the core layer and the surface layer, the longitudinal direction (surface layer long fiber) There is a problem that the interface between the surface layer and the core layer is distorted in the orientation direction) and the reliability of the long-term interlayer adhesion of peeling at the interface is poor.
[0006]
[Problems to be solved by the invention]
In view of such circumstances, the present invention can be expected to further improve the bending strength, and in the long term, a composite material excellent in interlayer adhesion, a synthetic sleeper using this composite material, and the manufacture of the composite material It aims to provide a method.
[0007]
[Means for Solving the Problems]
In order to achieve such an object, a composite material according to the invention of claim 1 of the present invention (hereinafter referred to as “composite material of claim 1”) is made of long fibers (A) oriented in the longitudinal direction and foamed. In the composite material made of the material including the resin (B) and the filler (C), a first layer that becomes a surface layer when in use, a second layer immediately below the first layer, and a third layer immediately below the second layer Each layer includes at least three layers, each layer containing the first layer of long fibers (A) (VA1)> second layer of long fibers (A) (VA2)> third layer of long fibers (A) content (VA2), first layer filler (C) content (VC1) <second layer filler (C) content (VC2) <third layer filler (C ) Content (VC3), the thickness t1 of the first layer as viewed in the vertical cross section in the longitudinal direction is T / 40 <t1 ≦ T / 5 with respect to the total thickness T, as viewed in the vertical cross section in the longitudinal direction. Thus, the thickness t2 of the second layer satisfies the condition of T / 40 <t2 ≦ T / 5 with respect to the total thickness T.
[0008]
The composite material according to the invention of claim 2 of the present invention (hereinafter referred to as “composite material of claim 2”) is a long fiber (A), a foamed resin (B) and a filler (C) oriented in the longitudinal direction. A first layer to be a surface layer, a second layer surrounded by the first layer from the outside, and a third layer surrounded by the second layer. Each layer, the content (VA1) of the long fibers (A) of the first layer> the content (VA2) of the long fibers (A) of the second layer> the content of the long fibers (A) of the third layer ( VA2), first layer filler (C) content (VC1) <second layer filler (C) content (VC2) <third layer filler (C) content (VC3) The total thickness tf of the first layer in the thickness direction as viewed in the vertical cross section in the longitudinal direction is T / 20 <tf ≦ 2T / 5 with respect to the total thickness T. The total thickness tc of the second layers in the thickness direction as viewed in the vertical cross section in the direction satisfies the condition of T / 20 <tc ≦ 2T / 5 with respect to the total thickness T.
[0009]
The composite material according to the invention of claim 3 of the present invention (hereinafter referred to as "composite material of claim 3") is the composite material of claim 1 or claim 2, wherein the first layer is a long fiber (A). 10 volume% or more and 40 volume% or less, and the filler (C) is contained 0 volume% or more and 20 volume% or less, and the third layer contains the filler (C) 20 volume% or more and 70 volume% or less. It was set as the structure.
[0010]
The composite sleeper according to claim 4 of the present invention uses the composite material according to any one of claims 1 to 3.
[0011]
The manufacturing method of the composite material according to the invention of claim 5 of the present invention (hereinafter referred to as “manufacturing method of claim 5”) is the composite to be obtained in obtaining the composite material of claim 1 or claim 2. While moving the long long fiber raw material constituting the long fibers (A) constituting each layer of the material into a plurality of small long fiber raw material groups and aligning them, they are advanced toward the inlet of the cylindrical mold, and these During the progress of the small-length fiber raw material group, from the upper side of each small-length fiber raw material group, at least the filler (C) is sprinkled on the small-length fiber group according to the amount of filler in each layer, and these small lengths While the fiber raw material group is in the process of progressing, the foamable resin liquid supplying step of sprinkling at least the foamable resin liquid corresponding to the foamed resin of each layer and the sprinkled foamable resin liquid from above each small-long fiber raw material group The fibers that make up each small length fiber raw material group After the impregnation step of impregnating, each small-length fiber raw material group impregnated with the foamable resin liquid is converged so as to be in the order of the layer structure of the composite material to be obtained, and guided into the mold, or foamed Among the small-length fiber raw material group impregnated with the conductive resin liquid, a filler (which becomes the innermost layer or the backmost layer further on the small-length fiber raw material group forming one surface side layer from the innermost layer or the backmost layer) C) and an innermost layer forming mixture or an innermost layer forming mixture comprising the foamable resin liquid, and each small fiber raw material group impregnated with the foaming resin liquid and the innermost layer forming mixture or the outermost layer forming The mixture was converged so as to be in the layer structure order of the molded body to be obtained and guided into the mold, and was heated and cured or melted in the mold to form a cross-sectional shape in the mold.
[0012]
In the present invention, the shape of the long fiber (A) is not limited as long as it has a function as a reinforcing fiber. For example, monofilaments, fibrils (things in which cocoon-like fibers protrude), Examples of the material include organic materials such as glass, carbon, and synthetic resin, and glass or carbon is preferable because it is reinforced and hardened.
[0013]
As the foamed resin (B), foamed rigid polyurethane resin having closed cells, urethane resin, phenol resin, polyester resin, epoxy resin, etc. Foamed phenolic resin, foamed epoxy resin, foamed urea resin, foamed methacrylic resin, etc., among which polyurethane foam has a relatively high mechanical strength and is non-water-absorbing to form closed cells when foamed And is preferably used.
[0014]
As filler (C), inorganic powder such as rock powder, glass powder, calcium silicate, cement concrete pulverized material, amorphous powder such as silica sand, inorganic short fiber such as sericite, wollastonite, etc. Examples thereof include inorganic powders having bubbles such as powder, vermiculite, pearlite, expanded shale, and fly ash hollow powder, and inorganic powders having a relatively small particle diameter such as calcium carbonate and fly ash. Also, organic powder particles such as resin chips and wood powder may be used.
[0015]
The composite material according to claim 1 may have four or more layers as long as it includes at least three layers of the first layer to the third layer.
Further, in the composite material according to claim 1, the thickness t1 of the first layer as viewed in the longitudinal section in the longitudinal direction is T / 40 <t1 ≦ T / 5 with respect to the total thickness T, and the thickness as viewed in the longitudinal section in the longitudinal direction. It is essential that the thickness t2 of the two layers satisfies the condition of T / 40 <t2 ≦ T / 5 with respect to the total thickness T. The reason is that the thickness t1 of the first layer and the second layer When the thickness t2 of the fiber is T / 40 or less, the bending characteristics are deteriorated, and when t1 and t2 exceed T / 5, the ratio of the total length of the long fibers (A) is large, which is not economical. It is.
[0016]
On the other hand, in the composite material according to claim 2, the total thickness tf of the first layer in the thickness direction as viewed in the vertical cross section in the longitudinal direction is T / 20 <tf ≦ 2T / 5 with respect to the total thickness T, It is essential that the total thickness tc of the second layers in the thickness direction in the vertical cross section satisfies the condition of T / 20 <tc ≦ 2T / 5 with respect to the total thickness T. When the total thickness tf of the first layer and the total thickness tc of the second layer are T / 20 or less, the bending characteristics are deteriorated. When tf and tc exceed 2T / 5, the entire long fiber (A) is formed. This is because it accounts for a large proportion and is not suitable in terms of economy.
[0017]
In the composite material according to claim 1 and claim 2, each layer has a long fiber (A) content (VA1) of the first layer> a long fiber (A) content (VA2) of the second layer> third. Layer long fiber (A) content (VA2), first layer filler (C) content (VC1) <second layer filler (C) content (VC2) <third layer The content (VC3) of the filler (C) is also indispensable because the elastic modulus between the layers does not change greatly and the long fibers (A) are aligned in this way. This is because the strain between the layers can be reduced under the bending load.
In addition, about the elasticity modulus of each layer, 1st layer> 2nd layer> 3rd layer is preferable, and when using as a sleeper like Claim 4, the elasticity modulus of 1st layer is 6000 Mpa or more, More preferably, the elastic modulus is 1000 MPa or more, and the elastic modulus of the third layer is 300 MPa or more.
[0018]
Furthermore, in the composite material according to claim 1 and the composite material according to claim 2, in the composite material according to claim 3, the first layer comprises 10% to 40% by volume of the long fibers (A) and 0% to 20% by volume. It is preferable that the filler (C) is contained in a volume% or less and that the third layer contains a filler (C) in a volume of 20 volume% or more and 70 volume% or less, because the length in the first layer If the content of the fiber (A) is less than 10% by volume, it is difficult to obtain an elastic modulus enhancement effect by reinforcing the long fiber regardless of the density of the foamed resin, and if it exceeds 40% by volume, poor dispersion with the weight occurs. If the content of the filler in the third layer is less than 20% by volume, it is difficult to expect economic improvement and compressibility of the third layer. If it exceeds 70% by volume, This is because poor dispersion with the resin may occur and the reinforcing effect may be deteriorated.
[0019]
The composite materials of claims 1 to 3 are preferably manufactured continuously as in the manufacturing methods of claims 5 and 6 in consideration of productivity, but may be manufactured in a batch manner. Absent.
In the manufacturing method according to claim 5, any one of the filler supply step and the foamed resin liquid supply step may be performed first or simultaneously. In other words, the filler can be supplied simultaneously by previously mixing the filler with the foamable resin liquid. Further, after the filler is sprinkled in a state where the filler is mixed in advance with a small amount of the foamable resin liquid in the filler supply step, the foamable resin liquid may be sprinkled separately.
In the manufacturing method of claim 5, the term “converging” includes the case of converging so as to be layered only in the thickness direction, or the case of converging so that the inner layer is sequentially surrounded by the outer layer.
[0020]
In addition, as a method for producing the composite material according to claim 1 in a batch method, for example, a foamable resin liquid is dispersed and mixed in a long fiber raw material with respect to a molding die in which one of four surfaces surrounding the longitudinal direction is opened. Or a mixture obtained by dispersing and mixing a filler and a foamable resin liquid in a long fiber material, or a mixture obtained by dispersing and mixing a filler and a foamable resin liquid. Set in a mold with a laminated body in which a preformed body b that becomes two layers and a preformed body c that becomes the third layer are sequentially laminated, and before the foamable resin liquid is foam-cured, the open surface of the mold is A method of foaming and curing a foamable resin after closing is mentioned.
[0021]
As a method for manufacturing the composite material according to claim 2, for example, two laminated bodies obtained by preforming the preforms a, b, and c in the same manner as described above are preformed in a mold. A method in which the foamed resin is heated and foam-cured after being set in the mold so that the bodies c are in contact with each other and closing the open surface of the mold before the foamable resin liquid is foam-cured. Is mentioned.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below in detail with reference to the drawings.
FIG. 1 shows one embodiment of a composite material according to the present invention.
[0023]
As shown in FIG. 1, the composite material 1 is made of a material including long fibers (A) oriented in the longitudinal direction, a foamed resin (B), and a filler (C), and a first layer 11 as a surface layer. And the second layer 12 as an intermediate layer and the third layer 13 as a core layer.
Each layer has a long fiber (A) content of the long fiber (A) of the first layer 11 (VA1)> the long fiber (A) content of the second layer 12 (VA2)> third layer. 13 of the long fiber (A) content (VA2) is satisfied, the filler (C) content is O, the filler content (VC1) of the first layer 11 is O, and 0 < The content of the second layer filler (C) (VC2) <the content of the third layer filler (VC3) is satisfied.
[0024]
In addition, the first layer 11 contains 10% by volume to 40% by volume of the long fibers (A) and 0% by volume to 20% by volume of the filler, and the third layer has a filler. Is contained in a ratio of 20% by volume to 70% by volume.
In addition, the thickness of each layer is such that the total thickness tf of the first layer 11 in the thickness direction (the arrow direction in FIG. 1) in the vertical cross section in the longitudinal direction is T / 20 <tf ≦ 2T / 5 with respect to the total thickness T. The total thickness tc of the second layer 12 satisfies the condition of T / 20 <tc ≦ 2T / 5 with respect to the total thickness T.
[0025]
As described above, since the composite material 1 contains a large amount of the long fibers (A) on both the uppermost surface and the lowermost surface in the thickness direction, the durability of the composite material 1 with respect to two directions perpendicular to the thickness direction is long. Will be expensive. In addition, the elastic modulus between the layers does not change greatly, and the effect of reducing the strain between the layers in the bending load along the long fiber (A) is obtained.
Therefore, the reliability of long-term interlayer adhesion is high, and it can be used effectively as a synthetic sleeper.
[0026]
Next, a method for manufacturing the composite material 1 will be described in detail with reference to FIG.
FIG. 2 schematically shows a manufacturing apparatus for manufacturing the composite material 1.
[0027]
As shown in FIG. 2, the manufacturing apparatus 2 includes two first layer raw material lines 2a and 2a, two second layer raw material supply lines 2b and 2b, and one third layer raw material supply line 2c. And a molding die (molding passage) 3 and a take-up machine 4.
The third layer raw material supply line 2c is provided at the center of the five lines, and the long fiber raw material 81 is a small long fiber for the third layer 13 by the take-up force of the take-up machine provided behind the molding die 3. While being arranged as a raw material group 82, it proceeds in the direction of the take-up machine 4 through the molding die 3, and includes a filler supply device 5, a resin liquid supply device 6, and an impregnation device 7. I have.
[0028]
The second layer raw material supply line 2b is provided so as to sandwich the third layer raw material supply line 2c from above and below, and the long fiber raw material 81 is for the upper part or the lower part in the thickness direction of the second layer 12, respectively. The small length fiber raw material groups 83 and 83 are arranged in the same manner as the third long length fiber raw material group 82, and proceed to the take-up machine 4 through the molding die 3 in the same manner as the third layer small length fiber raw material group 82. , A filler supply device 5, a resin liquid supply device 6, and an impregnation device 7 are provided.
[0029]
The first layer raw material supply line 2a is arranged such that one is located at the top of each line and the other is located at the bottom of each line, and the long fiber raw material 81 is an upper portion in the thickness direction of the first layer 11, respectively. Alternatively, while being arranged as a small-length fiber raw material group 84, 84 for the lower part, it proceeds in the direction of the take-up machine 4 through the molding die 3 in the same manner as the small-length fiber raw material group 82 for the third layer. And a resin liquid supply device 6 and an impregnation device 7 are provided.
[0030]
The filler supply device 5 is adapted to sprinkle from above the small-length fiber raw material group 83 (84) arranged in a predetermined amount in a state where the filler is previously mixed with the foamable resin liquid.
The resin liquid supply device 6 mixes the raw materials in the raw material tank (not shown) in the discharge device 61 and arranges the raw material groups 82 (83, 83) as foamable resin liquids 62. 84) is sprinkled from above.
[0031]
The impregnation apparatus 7 includes an impregnation plate 71 and an impregnation base (not shown) for receiving the impregnation plate 71, and the impregnating plate 71 and the impregnation base for the small-length fiber raw material group 82 (83, 84) supplied with the foamable resin liquid 62. And the impregnated plate 71 are slid to sandwich the small-length fiber raw material group 82 (83, 84) between the impregnated plate 71 and the impregnation table, and the small-long fiber raw material group 82 (83, 84) is The foamable resin liquid and the filler are uniformly impregnated and dispersed between the constituent fibers.
[0032]
The molding die 3 is formed in a cylindrical shape with a rectangular cross section by combining four endless belts 31 (only two are shown in the figure) that are rotationally driven in the same direction by a driving means, although not shown in the figure. The foamable resin liquid impregnated in the long fiber raw material group continuously fed into the molding die 3 is foamed and cured, and is molded into the inner shape of the molding die 3. .
[0033]
That is, the manufacturing apparatus 2 uses the long fiber raw material of the composite material 1 as a small fiber raw material group 84 serving as a reinforcing fiber for the upper portion in the thickness direction of the first layer 11 and the upper portion of the second layer 12 in the thickness direction. A small fiber raw material group 83 serving as a reinforcing fiber, a small fiber raw material group 82 serving as a reinforcing fiber of the third layer 13, a small fiber raw material group 83 serving as a reinforcing fiber in a lower portion of the second layer 12 in the thickness direction, The first layer 11 is advanced in the direction of the molding die 3 while being divided and aligned with the small fiber raw material group 84 which is the reinforcing fiber of the upper portion in the thickness direction of the first layer 11.
[0034]
Then, in the state of being divided into the respective small-length fiber raw material groups 82 (83, 84), the foamable resin liquid and / or the filler corresponding to each layer is placed in front of the molding die 3, and the small-long fiber raw material group 82, After sprinkling 83 and 84 from above, the impregnating apparatus 7 uniformly impregnates and disperses the foamable resin liquid and the filler.
Next, the respective small long fiber raw material groups 82 (83, 84) impregnated with the resin are converged so as to have a layer structure of the composite material to be obtained and placed in the molding die 3, and foamed in the molding die 3. The composite material 1 consisting of three layers is continuously manufactured by foaming and curing the conductive resin liquid.
[0035]
This manufacturing method can manufacture the composite material 1 continuously with good productivity as described above.
Also, since the first layer small long fiber raw material group 82 having a large proportion of long fibers (A) and no filler is arranged on the lowermost side, a part of the impregnated bundle of other layers after the resin impregnation falls. It will surely be fed into the mold without causing any problems. That is, it has excellent molding accuracy.
[0036]
The composite material and the manufacturing method thereof according to the present invention are not limited to the above embodiment. For example, in the composite material 2 of the above embodiment, the filler is not supplied to the first layer 11, but a small amount of filler may be supplied to the first layer.
In the above composite material, the third layer 13 which is the innermost layer also contains the long fibers (A). However, the innermost layer may be a layer made of only the filler (C) and the foamed resin (B). I do not care.
In order to provide such a layer consisting only of the filler (C) and the foamed resin (B) in the innermost layer, the foaming process has been carried out for the second layer 12 before the molding die. After supplying the mixture of the filler (C) having the composition of the innermost layer and the foamable resin liquid on the small-long fiber raw material group impregnated with the conductive resin liquid, What is necessary is just to make it converge so that it may become the layer structure order of the molded object which is going to obtain the innermost layer formation mixture.
[0037]
【Example】
In the following, embodiments of the present invention will be described in more detail.
[0038]
Example 1
The production apparatus 2 of FIG. 2, a glass monofilament strand (17 μm) as a long fiber raw material, a thermosetting urethane liquid as a foaming resin liquid (120 parts by weight of polyphenylmethane diisocyanate, 100 parts by weight of a propylene oxide-added polyether polyol, 1 part by weight of a silicone oil foam stabilizer, 1 part by weight of water, 0.5 part by weight of dibutyltin laurate), a silica sand No. 3 as a filler, and a first layer which is a surface layer as shown in FIG. A composite material composed of three layers of a second layer as a layer and a third layer as a core layer was obtained.
[0039]
The first layer has a thickness of 20 mm, a total thickness tf of 40 mm, a width of 150 mm, and a volume ratio of long fibers (A): foamed resin. (B): Filler (C) = 14: 86 (bubble ratio 0.6): 0.
[0040]
The thickness of the second layer of the composite material in the thickness direction is 10 mm for the upper surface portion and 10 mm for the lower surface portion, the total thickness tc is 20 mm, and the volume ratio is long fiber (A): foamed resin (B): filler. (C) = 5: 70 (bubble ratio 0.6): 25.
The third layer had a thickness of 40 mm, and the volume ratio was long fiber (A): foamed resin (B): filler (C) = 2: 50 (cell ratio 0.6): 48.
[0041]
(Example 2)
A glass monofilament strand (13 μm) as a long fiber material, a thermosetting urethane liquid similar to that of Example 1, a glass foam (particle size 3 mm) as a filler, and a first layer that becomes a surface layer in a batch system, A plate-like composite material consisting of three layers, a second layer serving as an intermediate layer and a third layer serving as a back layer, was obtained.
The first layer has a thickness of 20 mm, a width of 150 mm, and a volume ratio of long fiber (A): foamed resin (B): filler (C) = 12: 88. (Bubble ratio 0.5): 0.
[0042]
The thickness of the second layer of the composite material in the thickness direction is 10 mm for the upper surface portion and 10 mm for the lower surface portion, the total thickness tc is 20 mm, and the volume ratio is long fiber (A): foamed resin (B): filler. (C) = 10: 60 (bubble ratio 0.5): 30.
The third layer had a thickness of 80 mm and a volume ratio of long fiber (A): foamed resin (B): filler (C) = 8: 40 (cell ratio 0.6): 52.
[0043]
(Comparative Example 1)
Two layers including the first layer of Example 1 which is a surface layer and the third layer of Example 1 which is a core layer in the same manner as Example 1 except that the second layer which is an intermediate layer is not provided. A composite material of structure was obtained.
[0044]
(Comparative Example 2)
Two layers including the first layer of Example 1 which is a surface layer and the third layer of Example 2 which is a back surface layer in the same manner as Example 2 except that the second layer which is an intermediate layer is not provided. A composite material of structure was obtained.
[0045]
The composite materials obtained in Examples 1 and 2 and Comparative Examples 1 and 2 were subjected to a bending test and a fatigue test, respectively, and the results are shown in Table 1.
The bending strength is measured using the method of JIS Z 2101, and the fatigue test is performed by applying a load that is 60% of the bending strength at a frequency of 3 Hz 1,000,000 times, The broken and interfacial peeled materials were indicated with ×, and the ones that did not occur were indicated with ○.
[0046]
[Table 1]

[0047]
From Table 1 above, it can be seen that the composite material of the present invention exhibits excellent physical properties with excellent bending strength and no problem of delamination.
[0048]
【The invention's effect】
Since the composite material according to the present invention is configured as described above, it can be expected to further improve the bending strength, and has excellent adhesiveness between layers even in the long run.
Therefore, when used for synthetic sleepers, the durability is improved and the safety is also increased.
[0049]
Moreover, the manufacturing method of the composite material concerning this invention can manufacture the said composite material with sufficient continuous productivity.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of one embodiment of a composite material according to the present invention, cut along a vertical plane in its longitudinal direction.
FIG. 2 is a schematic view schematically showing an example of a manufacturing apparatus used in the method for manufacturing a composite material according to the present invention.
[Explanation of symbols]
1 Composite material 11 First layer (surface layer)
12 Second layer (intermediate layer)
13 Third layer (core layer)
3 Mold (molding passage)
62 Foamable resin liquids 82-84 Small fiber raw material group

Claims (5)

In a composite material made of a material including long fibers (A) oriented in the longitudinal direction, foamed resin (B), and filler (C), a first layer that becomes a surface layer in use, and a first layer immediately below the first layer 2 layers and at least three layers of a third layer immediately below the second layer, and each layer has a content of the long fibers (A) of the first layer (VA1)> long fibers of the second layer (A) Content (VA2)> Content (VA2) of long fiber (A) in the third layer, Content (VC1) of filler (C) in the first layer <Content of filler (C) in the second layer (VC2) <content of the filler (C) in the third layer (VC3), the thickness t1 of the first layer as viewed in the longitudinal section in the longitudinal direction is T / 40 <t1 ≦ T / 5 with respect to the total thickness T A composite material characterized in that the thickness t2 of the second layer satisfies the condition of T / 40 <t2 ≦ T / 5 with respect to the total thickness T when viewed in a vertical cross section in the longitudinal direction. In a composite material made of a material including a long fiber (A) oriented in the longitudinal direction, a foamed resin (B), and a filler (C), a first layer serving as a surface layer is surrounded from the outside by the first layer. It is composed of at least three layers of a second layer and a third layer surrounded by the second layer, and each layer has a content (VA1) of long fibers (A) of the first layer> long fibers of the second layer ( A) content (VA2)> third layer long fiber (A) content (VA2), first layer filler (C) content (VC1) <second layer filler (C) Content (VC2) <content of the filler (C) of the third layer (VC3), and the total thickness tf of the first layer in the thickness direction as viewed in the vertical cross section in the longitudinal direction is T / 20 <tf ≦ 2T / 5, the total thickness tc of the second layer in the thickness direction as seen in the vertical cross section in the longitudinal direction is T / 20 with respect to the total thickness T. <Tc ≦ 2T / 5 satisfies the condition. The first layer contains 10% to 40% by volume of the long fibers (A) and 0% to 20% by volume of the filler (C), and the third layer contains the filler (C). The composite material according to claim 1 or 2, which is contained in an amount of 20% by volume to 70% by volume. A synthetic sleeper using the composite material according to any one of claims 1 to 3. In obtaining the composite material according to claim 1 or 2, the long long fiber raw material to be the long fibers (A) constituting each layer of the composite material to be obtained is divided into a plurality of small long fiber raw material groups. While aligning, advance in the inlet direction of the cylindrical mold,
During the progress of these small-length fiber raw material groups, from above each small-length fiber raw material group, at least a filler (C) is sprinkled on the small-long fiber group according to the amount of filler in each layer;
During the progression of these small-length fiber raw material groups, from above each small-length fiber raw material group, at least a foamable resin liquid supply step of sprinkling a liquid amount corresponding to the foamed resin of each layer,
After undergoing an impregnation step of impregnating the sprinkled foamable resin liquid between the fibers constituting each small-length fiber raw material group,
Each small fiber raw material group impregnated with the foamable resin liquid is converged so as to be in the layer configuration order of the composite material to be obtained and guided into the mold, or
Among the small-length fiber raw material group impregnated with the foamable resin liquid, a filler that becomes the innermost layer or the backmost layer further on the small-length fiber raw material group that forms one surface side layer from the innermost layer or the backmost layer. The innermost layer forming mixture or innermost layer forming mixture or innermost layer forming mixture formed by supplying the innermost layer forming mixture or the outermost back layer forming mixture comprising (C) and the foaming resin solution and impregnated with the expanding resin solution The mixture is made to converge in the order of the layer structure of the molded body to be obtained, and led into the mold,
A method for producing a composite material, wherein the composite material is molded into a cross-sectional shape in a mold by heat curing or heat melting in the mold.

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