Fiber-reinforced resin hollow body and method for manufacturing same

Abstract

A fiber-reinforced resin hollow body includes an axial-direction fiber layer containing reinforcing fibers aligned parallel to an axial direction of the hollow body, and a non-axial-direction fiber layer provided on top of at least one of an internal and an external side of the axial-direction fiber layer, and containing reinforcing fibers oriented in a direction different from a direction in which the reinforcing fibers contained in the axial-direction fiber layer are aligned. The non-axial-direction fiber layer has end portions in a peripheral direction of the hollow body, the end portions overlapping each other.

Claims

1. A fiber-reinforced resin hollow body having an elongated shape comprising: an axial-direction fiber layer containing reinforcing fibers aligned parallel to an axial direction of the hollow body, the axial direction of the hollow body being the longitudinal direction thereof; a non-axial-direction fiber layer provided on top of at least one of an internal and an external side of the axial-direction fiber layer, and containing reinforcing fibers oriented in a direction different from a direction in which the reinforcing fibers contained in the axial-direction fiber layer are aligned; and a non-axial-direction fiber layer disposed at the innermost surface of the hollow body, and containing reinforcing fibers oriented in a direction different from a direction in which the reinforcing fibers contained in the axial-direction-fiber layer are aligned, wherein the non-axial-direction fiber layer provided on top of at least one of an internal and an external side of the axial-direction fiber layer is divided into four layers along the periphery of the hollow body, perpendicular to the axial direction of the hollow body, and an end portion of one of the four layers overlaps an end portion of a different one of the four layers along the periphery, the one and the different one being adjacent to each other, the non-axial-direction fiber layer disposed at the innermost surface of the hollow body is not divided into two or more fiber layers along the periphery of the hollow body, and end portions of the non-axial-direction fiber layer itself overlap each other.

2. The fiber-reinforced resin hollow body of claim 1, wherein the non-axial-direction fiber layer includes one or more fiber layers selected from the group consisting of a peripheral-direction fiber layer containing reinforcing fibers aligned parallel to the periphery of the fiber-reinforced resin hollow body, a non-aligned fiber layer containing reinforcing fibers not aligned in a specific direction, a woven fiber layer containing reinforcing fibers constituting a weave structure, a braided fiber layer containing reinforcing fibers constituting a braid structure, and a knitted fiber layer containing reinforcing fibers constituting a knit structure.

3. The fiber-reinforced resin hollow body of claim 1, wherein the non-axial-direction fiber layer provided on top of at least one of an internal and an external side of the axial-direction fiber layer is provided on top of both the internal and external sides of the axial-direction fiber layer.

4. The fiber-reinforced resin hollow body of claim 1, wherein the fiber-reinforced resin hollow body has a rectangular shape in the vertical cross-section with respect to the axial direction, and the end portions of the non-axial-direction fiber layer provided on top of at least one of an internal and an external side of the axial-direction fiber layer overlap each other at or near an angled portion of the rectangular shape.

5. The fiber-reinforced resin hollow body of claim 1, wherein the mass ratio of all the reinforcing fibers of the axial-direction fiber layer to all the reinforcing fibers of the non-axial-direction fiber layer is 100:20-100:200.

6. The fiber-reinforced resin hollow body of claim 1, wherein the non-axial-direction fiber layer includes one or more fiber layers extending along the periphery and one or more non-aligned fiber layers.

7. The fiber-reinforced resin hollow body of claim 6, wherein at least one of the one or more non-aligned fiber layers is disposed at a most peripheral surface of the fiber-reinforced resin hollow body.

8. The fiber-reinforced resin hollow body of claim 7, wherein the at least one of the one or more non-aligned fiber layers disposed at the most peripheral surface is disposed adjacent to at least one of the one or more peripherally extending fiber layers.

9. The fiber-reinforced resin hollow body of claim 6, wherein the mass ratio of all the reinforcing fibers of the axial-direction fiber layer to all the reinforcing fibers of the one or more peripherally extending fiber layers is 100:1-100:100, and the mass ratio of all the reinforcing fibers of the axial-direction fiber layer to all the reinforcing fiber of the one or more non-aligned fiber layers is 100:10-100:100.

10. The fiber-reinforced resin hollow body of claim 1, wherein the fiber-reinforced resin hollow body is impregnated with a curable resin.

11. The fiber-reinforced resin hollow body of claim 1, wherein the fiber-reinforced resin hollow body has a thickness of 1-20 mm.

12. The fiber-reinforced resin hollow body of claim 1, wherein the fiber-reinforced resin hollow body has an outer perimeter of 125-300 mm.

13. The fiber-reinforced resin hollow body of claim 1, wherein the fiber-reinforced resin hollow body is a member for directly or indirectly supporting and fixing an automotive instrument panel.

14. The fiber-reinforced resin hollow body of claim 13, wherein the member is a cross-car beam.

15. The fiber-reinforced resin hollow body of claim 1, wherein a breaking load measured by a bending test is 8000 N or more and 30000 N or less.

16. A method for manufacturing the fiber-reinforced resin hollow body of claim 1 by pultrusion.

17. The fiber-reinforced resin hollow body of claim 2, wherein the non-axial-direction fiber layer provided on top of at least one of an internal and an external side of the axial-direction fiber layer is provided on top of both the internal and external sides of the axial-direction fiber layer.

18. The fiber-reinforced resin hollow body of claim 2, wherein the fiber-reinforced resin hollow body has a rectangular shape in the vertical cross-section with respect to the axial direction, and the end portions of the non-axial-direction fiber layer provided on top of at least one of an internal and an external side of the axial-direction fiber layer overlap each other at or near an angled portion of the rectangular shape.

19. The fiber-reinforced resin hollow body of claim 4, wherein the end portions overlapping each other of the non-axial-direction fiber layer disposed at the innermost surface of the hollow body are disposed at a side portion in between the two adjacent angled portions of the rectangular shape.

20. The fiber-reinforced resin hollow body of claim 4, wherein the term “at or near an angled portion” with respect to an overlap portion in the vertical cross-section means that the distance between the vertex of the angled portion and the overlap portion is within 5 mm, the end portions overlapping each other of the non-axial-direction fiber layer disposed at the innermost surface of the hollow body are disposed at a side portion in between the vertexes of the two adjacent angled portions of the rectangular shape other than at or near the angled portion.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic diagram showing a rough cross-section perpendicular to an axial direction in an example fiber-reinforced resin hollow body of the present technology disclosed herein.

(2) FIG. 2 is a schematic diagram showing a rough cross-section perpendicular to an axial direction in an example fiber-reinforced resin hollow body of the present technology disclosed herein.

(3) FIG. 3 is a schematic diagram showing a rough cross-section perpendicular to an axial direction in an example fiber-reinforced resin hollow body of the present technology disclosed herein.

(4) FIG. 4 is a schematic diagram showing a rough cross-section perpendicular to an axial direction in an example fiber-reinforced resin hollow body of the present technology disclosed herein.

(5) FIG. 5 is a schematic diagram showing a rough configuration of an example manufacturing apparatus for manufacturing, by pultrusion, the fiber-reinforced resin hollow body of the present technology disclosed herein.

(6) FIG. 6 is a schematic diagram showing a rough cross-section perpendicular to an axial direction of a conventional fiber-reinforced resin hollow body.

(7) FIG. 7A is a diagram for describing a procedure for a bending test that was carried out using specimens of examples and comparative examples.

(8) FIG. 7B is a diagram for describing a procedure for a bending test that was carried out using specimens of examples and comparative examples.

(9) FIG. 7C is a diagram for describing a procedure for a bending test that was carried out using specimens of examples and comparative examples.

(10) FIG. 8 is a diagram showing shapes and dimensions of specimens of examples and comparative examples.

(11) FIG. 9 is a diagram showing materials used in specimens of examples and comparative examples.

(12) FIG. 10A is a diagram for describing a configuration of a specimen of Comparative Example 1.

(13) FIG. 10B is a diagram for describing a configuration of a specimen of Example 1.

(14) FIG. 10C is a diagram for describing a configuration of a specimen of Example 2.

(15) FIG. 10D is a diagram for describing a configuration of a specimen of Example 3.

(16) FIG. 11 is a graph showing breaking loads of the specimens of Examples 1-3 and Comparative Example 1.

(17) FIG. 12 is a graph showing flexural moduli of the specimens of Examples 1-3 and Comparative Example 1.

DESCRIPTION OF EMBODIMENTS

(18) Embodiments of the present technology disclosed herein will now be described in detail with reference to the accompanying drawings. The embodiments described below are merely preferred examples in nature and are not intended to limit the present technology disclosed herein, application, or uses.

(19) [Fiber-Reinforced Resin Hollow Body]

(20) A fiber-reinforced resin hollow body according to the present technology disclosed herein will be described in detail with reference to the drawings. Parts shown in the drawings are merely schematically shown for ease of understanding the present technology disclosed herein, and may not be to scale and have external appearances different from actual ones. Note that the term “vertical direction” directly or indirectly used herein refers to the vertical direction in the drawings. Unless otherwise specified, like members, portions, dimensions, or regions are indicated by like reference characters throughout the drawings.

(21) A fiber-reinforced resin hollow body (may also be hereinafter simply referred to as a “hollow body”) according to the present technology disclosed herein is a body having an elongated shape and impregnated with a curable resin, more specifically an elongated molded body having a hollow shape and including fiber layers containing reinforcing fibers and a curable resin permeating the fiber layers and cured. The longitudinal direction of the hollow body is referred to as an “axial direction.”

(22) (Fiber Layers)

(23) The fiber layers containing reinforcing fibers in the hollow body of the present technology disclosed herein include at least an axial-direction fiber layer and a non-axial-direction fiber layer provided on top of at least one of the internal side and external side of the axial-direction fiber layer. Although, for example, a hollow body 10 of the present technology disclosed herein shown in FIG. 1 has an axial-direction fiber layer 1, and non-axial-direction fiber layers 2 and 3 on both the internal and external sides of the axial-direction fiber layer 1, a non-axial-direction fiber layer is provided on at least one of the internal and external sides of the axial-direction fiber layer 1. The hollow body 10 preferably has a non-axial-direction fiber layer on at least the internal side of the axial-direction fiber layer 1, more preferably on both the internal and external sides, in terms of the strength of the hollow body. A non-axial-direction fiber layer provided on top of the internal side of the axial-direction fiber layer 1 may also be herein referred to as an “internal non-axial-direction fiber layer,” and is indicated by a reference character “2” in FIG. 1. A non-axial-direction fiber layer provided on top of the external side of the axial-direction fiber layer 1 may also be herein referred to as an “external non-axial-direction fiber layer,” and is indicated by a reference character “3” in FIG. 1.

(24) The axial-direction fiber layer 1 refers to a fiber layer that mainly contains reinforcing fibers aligned parallel to the axial direction (longitudinal direction) of the hollow body. In the present technology disclosed herein, the axial-direction fiber layer 1 preferably contains only reinforcing fibers aligned parallel to the axial direction of the hollow body. Such a preferable axial-direction fiber layer does not necessarily contain exactly only reinforcing fibers aligned parallel to the axial direction of the hollow body. In such a preferable axial-direction fiber layer, 95 mass % or more, preferably 98 mass % or more, of the reinforcing fibers contained therein are aligned substantially parallel to the axial direction of the hollow body. As used herein, the term “substantially parallel” with respect to reinforcing fibers and the axial direction of the hollow body means that the angle between the reinforcing fibers and the axial direction of the hollow body falls within the range of ±10°.

(25) The reinforcing fibers constituting the axial-direction fiber layer 1 may be any fibers that have been conventionally used in the fiber-reinforced plastic field. Examples of the reinforcing fibers constituting the axial-direction fiber layer 1 include glass fibers and carbon fibers. The reinforcing fibers constituting the axial-direction fiber layer 1 are preferably glass fibers. Rovings (bundles of glass fibers) of the reinforcing fibers constituting the axial-direction fiber layer 1 typically fall within the range of 500-5000 tex (g/km). Although the axial-direction fiber layer 1 may contain other fibers in addition to the reinforcing fibers, the reinforcing fibers preferably accounts for 95 mass % or more, more preferably 98 mass % or more, of all the fibers contained in the axial-direction fiber layer 1.

(26) Specifically, for example, the axial-direction fiber layer 1 may contain rovings (bundles of glass fibers), and the number of glass fibers constituting the axial-direction fiber layer 1 is preferably uniform in a peripheral direction of the hollow body. The term “peripheral direction” with respect to the hollow body means a peripheral direction of a cross-section of the hollow body perpendicular to the axial direction of the hollow body.

(27) The amount of the fibers in the axial-direction fiber layer 1 is determined according to the desired strength and dimensions of the hollow body. For example, when the hollow body is used as a member for supporting and fixing an automotive instrument panel (a square-tube member having a size of 3-10 cm×3-10 cm), the amount of the fibers in the axial-direction fiber layer 1 per meter of the length of the hollow body is typically 50-1000 g/m.

(28) The non-axial-direction fiber layers 2 and 3 may be any fiber layer that contains reinforcing fibers aligned or oriented in a direction different from that in the axial-direction fiber layer 1. The term “aligned or oriented in a direction different from that in the axial-direction fiber layer 1” with respect to reinforcing fibers contained in a non-axial-direction fiber layer means that the reinforcing fibers contained in the non-axial-direction fiber layer are aligned in a specific direction (e.g., the peripheral direction of the hollow body) that is not parallel to the direction in which the reinforcing fibers of the axial-direction fiber layer 1 are aligned, or are oriented in directions that are not limited to any specific direction (e.g., are randomly oriented). Note that the random orientation encompasses irregularly random orientation and regularly random orientation.

(29) The reinforcing fibers constituting the non-axial-direction fiber layers 2 and 3 may each independently be any fibers that have been conventionally used in the fiber-reinforced plastic field, as with the reinforcing fibers constituting the axial-direction fiber layer 1. Examples of the reinforcing fibers constituting the non-axial-direction fiber layers 2 and 3 include glass fibers and carbon fibers. The reinforcing fibers constituting the non-axial-direction fiber layers 2 and 3 are preferably glass fibers. The reinforcing fibers constituting the non-axial-direction fiber layers 2 and 3 have a diameter falling within a range similar to that of the reinforcing fibers of the axial-direction fiber layer. Although the non-axial-direction fiber layers 2 and 3 may contain other fibers in addition to the reinforcing fibers, the reinforcing fibers preferably accounts for 95 mass % or more, more preferably 98 mass % or more, of all the fibers contained in the non-axial-direction fiber layers 2 and 3.

(30) The weights (per unit area) of the non-axial-direction fiber layers 2 and 3 are each independently determined according to the desired strength and dimensions of the hollow body. For example, when the hollow body is used as a member for supporting and fixing an automotive instrument panel (a square-tube member having a size of 3-10 cm×3-10 cm), the weights (per unit area) of the non-axial-direction fiber layers 2 and 3 of the hollow body are each independently typically 10-1000 g/m.sup.2, preferably 100-500 g/m.sup.2.

(31) The mass ratio of all the reinforcing fibers of the axial-direction fiber layer to all the reinforcing fibers of the non-axial-direction fiber layers is typically 100:20-100:200, and in terms of the strength of the hollow body, preferably 100:30-100:150, more preferably 100:50-100:120. All the reinforcing fibers of the non-axial-direction fiber layers refers to all the reinforcing fibers of the internal non-axial-direction fiber layer 2 and the external non-axial-direction fiber layer 3.

(32) Specifically, the non-axial-direction fiber layers 2 and 3 may each independently, for example, be selected from the group consisting of peripheral-direction fiber layers, non-aligned fiber layers, woven fiber layers, braided fiber layers, and knitted fiber layers.

(33) The peripheral-direction fiber layer refers to a fiber layer containing reinforcing fibers aligned parallel to the peripheral direction of the hollow body. In the present technology disclosed herein, the peripheral-direction fiber layer preferably contains only reinforcing fibers aligned parallel to the peripheral direction of the hollow body. Such a preferable peripheral-direction fiber layer does not necessarily contain exactly only reinforcing fibers aligned parallel to the peripheral direction of the hollow body. In such a preferable peripheral-direction fiber layer, 95 mass % or more, preferably 98 mass % or more, of the reinforcing fibers contained therein are aligned substantially parallel to the peripheral direction of the hollow body. As used herein, the term “substantially parallel” with respect to reinforcing fibers and the peripheral direction of the hollow body means that the angle between the reinforcing fibers and the peripheral direction of the hollow body falls within the range of ±10°.

(34) As a specific example of the peripheral-direction fiber layer, for example, a so-called cord-fabric reinforcing fiber sheet is preferably used. The cord-fabric reinforcing fiber sheet refers to a fiber sheet containing a plurality of reinforcing fiber bundles (e.g., each bundle contains 8-120 reinforcing fibers) that are arranged side by side and substantially equally spaced with each bundle running parallel to a first direction (e.g., the peripheral direction of the hollow body), and are tied together using linking threads in a second direction perpendicular to the first direction. The linking thread may be formed of either a thermoplastic polymer or reinforcing fibers. A roving of reinforcing fibers (a bundle of glass fibers) contained in the peripheral-direction fiber layer is typically within the range of 100-1000 tex (g/km).

(35) The non-aligned fiber layer refers to a fiber layer containing reinforcing fibers that are not aligned in any specific direction (e.g., reinforcing fibers are irregularly randomly oriented). Examples of the non-aligned fiber layer include nonwoven fabric layers of reinforcing fibers, and peripheral direction fiber-containing nonwoven fabric layers of reinforcing fibers.

(36) As the nonwoven fabric layer, for example, a so-called chopped strand mat of reinforcing fibers is preferably used. The chopped strand mat of reinforcing fibers refers to a nonwoven fabric layer containing chopped reinforcing fibers having a fiber length of 6-66 mm that are bonded together using a binder resin. A chopped strand mat used as the nonwoven fabric layer of the peripheral direction fiber-containing nonwoven fabric layer of reinforcing fibers may be formed by randomly sewing chopped reinforcing fibers on the cord-fabric reinforcing fiber sheet. The binder typically includes a thermoplastic polymer.

(37) The peripheral direction fiber-containing nonwoven fabric layer may be a composite fiber layer obtained by bonding a plurality of reinforcing fiber bundles (peripheral direction fiber bundles) (e.g., each bundle contains 8-120 reinforcing fibers) to the nonwoven fabric layer of reinforcing fibers such that the bundles are aligned parallel to the peripheral direction of the hollow body and equally spaced. Alternatively, the peripheral direction fiber-containing nonwoven fabric layer may be a composite fiber layer obtained by randomly sewing and fixing chopped reinforcing fibers having a fiber length of 6-66 mm on the cord-fabric reinforcing fiber sheet. As the peripheral direction fiber-containing nonwoven fabric layer, for example, a chopped strand mat cord fabric is preferably used. The chopped strand mat cord fabric refers to a composite mat obtained by randomly sewing chopped reinforcing fibers having a fiber length of 6-66 mm on the cord-fabric reinforcing fiber sheet. The sewing thread may be either a thread of a thermoplastic polymer or a thread of reinforcing fibers. The mass ratio of all the reinforcing fibers of the nonwoven fabric layer to all the reinforcing fibers as the peripheral direction fibers is typically 100:20-100:200, and in terms of the strength of the hollow body, preferably 100:30-100:150, more preferably 100:50-100:120.

(38) The woven fiber layer may be any fiber layer containing reinforcing fibers that form a weave structure. Examples of the weave structure include plain weave, twill weave, satin weave, and double weave. The reinforcing fibers of the woven fiber layer are regularly randomly oriented.

(39) The braided fiber layer may be any fiber layer containing reinforcing fibers that form a braid structure. The reinforcing fibers of the braided fiber layer are regularly randomly oriented.

(40) The knitted fiber layer may be any fiber layer containing reinforcing fibers that form a knit structure. Examples of the knit structure include weft knit and warp knit. The reinforcing fibers of the knitted fiber layer are regularly randomly oriented.

(41) In the present technology disclosed herein, the non-axial-direction fiber layers overlap each other at end portions in the peripheral direction thereof. Specifically, as shown in FIG. 1, in a cross-section taken in a direction perpendicular to the axial direction of the hollow body (may also be hereinafter simply referred to as a “vertical cross-section”), a first end portion of the non-axial-direction fiber layer (2, 3) is disposed on top of a second end portion at a joint portion of these end portions, so that an overlap portion 4a, 4b is formed. The overlap portion is formed continuously in the axial direction of the hollow body. As a result, the hollow body can acquire a sufficiently high strength. Unless the overlap portion is not formed at the end portions, the end portions relatively easily initiate the breaking of the fiber layer.

(42) Like the internal non-axial-direction fiber layer 2 of FIG. 1, a non-axial-direction fiber layer may be a single fiber layer, i.e., is not divided into two or more fiber layers in the peripheral direction of the hollow body, and end portions of the fiber layer itself may overlap each other to form an overlap portion 4a. In FIG. 1, end portions of the internal non-axial-direction fiber layer 2 itself overlap each other to form a single overlap portion 4a in the peripheral direction.

(43) Like the external non-axial-direction fiber layer 3 of FIG. 1, a non-axial-direction fiber layer may is divided into two or more layers in the peripheral direction of the hollow body, and end portions in the peripheral direction of adjacent ones of the two or more fiber layers may overlap each other to form an overlap portion 4b. In FIG. 1, the external non-axial-direction fiber layer 3 is divided into four layers in the peripheral direction of the hollow body, and end portions in the peripheral direction of adjacent ones of the four fiber layers overlap each other to form a total of four overlap portions 4b in the peripheral direction.

(44) Although the hollow body 10 has a square shape in the vertical cross-section of FIG. 1, the present disclosure is not limited to this as long as the hollow body 10 has a hollow shape. Specific examples of the vertically cross-sectional shape of the hollow body 10 include rectangular shapes, circular shapes, elliptical shapes, pentagonal or higher polygonal shapes, and composite shapes thereof. Rectangular shapes may include any suitable quadrilateral shapes, such as square shapes and rectangular shapes. In automotive applications, the hollow body preferably has a rectangular shape, particularly a square shape, in terms of ease of attachment to various members.

(45) The position where the overlap portion is formed is not particularly limited.

(46) In the case where the vertical cross-section of the hollow body has, for example, a rectangular shape or polygonal shape, end portions of the non-axial-direction fiber layer 3 preferably overlap each other at or near an angled portion of that shape in terms of improvement in design. This is because the overlap is not very noticeable if it is positioned at or near an angled portion of these shapes. Therefore, for a similar reason, in the case where the hollow body has a rectangular shape or polygonal shape, the non-axial-direction fiber layer preferably is divided into two or more layers (particularly, 2-4 fiber layers) in the peripheral direction of the hollow body with each end portion thereof in the peripheral direction of the hollow body being positioned at or near an angled portion, like the external non-axial-direction fiber layer 3 of FIG. 1. As a result, end portions in the peripheral direction of adjacent ones of the two or more (particularly, 2-4) fiber layers overlap each other at or near angled portions, so that overlap portions 4b are formed at or near the angled portions. Note that the term “at or near an angled portion” with respect to an overlap portion in the vertical cross-section means that the distance between the vertex of the angled portion and the overlap portion is within 5 mm. For example, the distance is preferably 0 mm, like the overlap portions 4b of FIG. 1.

(47) The internal non-axial-direction fiber layer(s) 2, particularly a non-axial-direction fiber layer disposed at the innermost surface of the hollow body, is preferably a single fiber layer, i.e., is not divided into two or more fiber layers in the peripheral direction of the hollow body, and end portions of that fiber layer 2 itself preferably overlap each other, in terms of use of the cavity of the hollow body for transport.

(48) An overlap width t of the overlap portion in the vertical cross-section is not particularly limited as long as the advantage of the present technology disclosed herein is obtained. For example, the overlap width t is typically 0.01×d to 0.5×d, preferably 0.1×d to 0.2×d, where d is a dimension of the hollow body. In the case where the hollow body has a rectangular shape, the dimension d of the hollow body is ¼ of the entire outer perimeter of the vertical cross-section of the hollow body. In the case where the hollow body has a circular shape, the dimension d of the hollow body is the outer diameter of the vertical cross-section. In the case where the hollow body has an elliptical shape, the dimension d of the hollow body is (the major axis length+minor axis length of the outer perimeter of the vertical cross-section)/2. In the case where the hollow body has a polygonal shape, the dimension d of the hollow body is the outer diameter of a circle approximating to the polygonal shape, i.e., a circle having the same area as that of the polygonal shape.

(49) In the present technology disclosed herein, not all end portions of the non-axial-direction fiber layers need to form an overlap portion. At least one pair of end portions in the peripheral direction of the non-axial-direction fiber layers overlap each other in the vertical cross-section. All the end portions preferably form an overlap portion in the vertical cross-section of the hollow body, in terms of further improvement in the strength of the hollow body.

(50) The value (average value) of a breaking load (N) of the hollow body 10 as measured in a bending test described below varies depending on the proportions of materials for each layer of the hollow body 10, etc., and therefore, is not particularly limited. In terms of imparting a sufficiently high strength to the hollow body 10, the value of the breaking load is preferably 8000 N or more 30000 N or less, more preferably 9000 N or more 20000 N or less, and particularly preferably 10000 N or more 15000 N or less.

(51) The value (average value) of a flexural modulus (GPa) of the hollow body 10 as measured in a bending test described below varies depending on the proportions of materials for each layer of the hollow body 10, etc., and therefore, is not particularly limited. In terms of imparting good workability to the hollow body 10, the value of the flexural modulus is preferably 18 GPa or more 50 GPa or less, more preferably 24.5 GPa or more 40 GPa or less, and particularly preferably 25 GPa or more 30 GPa or less.

(52) Concerning the values of the breaking load and flexural modulus, it is desirable that the breaking load should fall within the above range. More preferably, both the values of the breaking load and flexural modulus desirably fall within the above respective ranges in terms of obtaining the hollow body 10 simultaneously having a high strength and good workability.

Embodiment of FIG. 2

(53) Other embodiments of the present technology disclosed herein will now be described in detail. Note that, in the description of these embodiments, the same parts as those of the embodiment of FIG. 1 are indicated by the same reference characters and will not be described in detail.

(54) In FIG. 1, the non-axial-direction fiber layers 2 and 3 (the internal non-axial-direction fiber layer 2 and the external non-axial-direction fiber layer 3) each include a single fiber layer, or alternatively, may each independently include two or more fiber layers as shown in FIG. 2. Specifically, the non-axial-direction fiber layers 2 and 3 may each independently, for example, include two or more fiber layers selected from the group consisting of the above peripheral-direction fiber layers, non-aligned fiber layers, woven fiber layers, braided fiber layers, and knitted fiber layers. In this case, the mass ratio of all the reinforcing fibers of the axial-direction fiber layer to all the reinforcing fibers of all the non-axial-direction fiber layers is within the above range. Although the internal non-axial-direction fiber layer 2 and the external non-axial-direction fiber layer 3 of the hollow body of FIG. 2 both include two or more fiber layers, only one of the internal non-axial-direction fiber layer 2 and the external non-axial-direction fiber layer 3 may include two or more fiber layers.

(55) Unless otherwise specified, a hollow body 10a of FIG. 2 is similar to the hollow body of FIG. 1. For example, the hollow body 10a of FIG. 2 is similar to the hollow body of FIG. 1, except that the internal non-axial-direction fiber layer 2 and the external non-axial-direction fiber layer 3 both include two or more fiber layers. Specifically, the hollow body 10a of FIG. 2 has a vertical cross-section having a rectangular shape, and has an axial-direction fiber layer 1, a first internal non-axial-direction fiber layer 21a and a second internal non-axial-direction fiber layer 22a that are provided on top of the internal side of the axial-direction fiber layer 1, and a first external non-axial-direction fiber layer 31a and a second external non-axial-direction fiber layer 32a that are provided on top of the external side of the axial-direction fiber layer 1. In FIG. 2, the axial-direction fiber layer 1 is similar to one that has been described above. The first internal non-axial-direction fiber layer 21a, the second internal non-axial-direction fiber layer 22a, the first external non-axial-direction fiber layer 31a, and the second external non-axial-direction fiber layer 32a are each independently selected from a range similar to that of the non-axial-direction fiber layers 2 and 3 described above.

(56) Even in the case where a non-axial-direction fiber layer includes two or more fiber layers, not all end portions of the non-axial-direction fiber layer need to form an overlap portion. At least one pair of end portions in the peripheral direction of the non-axial-direction fiber layer overlap each other in the vertical cross-section. In particular, in the case where a non-axial-direction fiber layer includes two or more fiber layers, at least one pair of end portions in the peripheral direction preferably overlap each other for each fiber layer. All the end portions preferably form an overlap portion in the vertical cross-section of the hollow body, in terms of further improvement in the strength of the hollow body. Unless otherwise specified, the overlap portion formation position, overlap width t, separation form, shape in the vertical cross-section of the hollow body, etc., of each fiber layer included in the non-axial-direction fiber layer are similar to the above case where the non-axial-direction fiber layers include a single fiber layer.

(57) For example, end portions in the peripheral direction of each of the first internal non-axial-direction fiber layer 21a, the first external non-axial-direction fiber layer 31a, and the second external non-axial-direction fiber layer 32a preferably overlap each other. In terms of further improvement in the strength of the hollow body, each non-axial-direction fiber layer more preferably is divided into four layers in the peripheral direction of the hollow body with end portions thereof being positioned at or near angled portions, as shown in FIG. 2. As a result, in each of the first internal non-axial-direction fiber layer 21a, the first external non-axial-direction fiber layer 31a, and the second external non-axial-direction fiber layer 32a, end portions in the peripheral direction of adjacent ones of the four fiber layers overlap each other, so that four overlap portions 4b are formed at or near angled portions. End portions in the peripheral direction of the innermost internal non-axial-direction fiber layer, i.e., the second internal non-axial-direction fiber layer 22a, also preferably overlap each other. More preferably, as shown in FIG. 2, the second internal non-axial-direction fiber layer 22a is a single fiber layer, i.e., is not divided into two or more fiber layers in the peripheral direction of the hollow body, and end portions of that fiber layer 22a itself preferably overlap each other, in terms of use of the cavity of the hollow body for transport.

(58) In the case where a non-axial-direction fiber layer includes two or more fiber layers, the non-axial-direction fiber layer (at least one of, preferably both of, the internal non-axial-direction fiber layer 2 and the external non-axial-direction fiber layer 3) preferably includes one or more peripheral-direction fiber layers and one or more non-aligned fiber layers in terms of further improvement in the strength of the hollow body. This is because reinforcing fibers of a peripheral-direction fiber layer adjacent to a non-aligned fiber layer are allowed to be more easily aligned parallel to the peripheral direction, so that the strength of the hollow body is further improved. For example, as shown in FIG. 2, the non-axial-direction fiber layers 2 and 3 each preferably include one or more peripheral-direction fiber layers and one or more non-aligned fiber layers.

(59) In the case where a non-axial-direction fiber layer includes one or more peripheral-direction fiber layers and one or more non-aligned fiber layers, either a non-aligned fiber layer or a peripheral-direction fiber layer may be disposed at a most peripheral surface of the hollow body 10, i.e., an outermost surface or an innermost surface. Note that, in terms of improvement in the design of the external appearance, a non-aligned fiber layer is preferably disposed at a most peripheral surface of the hollow body. In this case, the non-aligned fiber layer is preferably adjacent to a peripheral-direction fiber layer. If a non-aligned fiber layer is disposed at a most peripheral surface, a direct influence of a die on a peripheral-direction fiber layer is reduced, and therefore, in the peripheral-direction fiber layer adjacent to the non-aligned fiber layer, reinforcing fibers are more easily aligned parallel to the peripheral direction, resulting in improvement in the design of the external appearance of the hollow body. Here, the term “non-aligned fiber layer is disposed at a most peripheral surface of the hollow body” means that the non-aligned fiber layer is disposed at the innermost surface of the hollow body in the internal non-axial-direction fiber layer 2, or as the outermost surface of the hollow body in the external non-axial-direction fiber layer 3. For example, as shown in FIG. 2, the first internal non-axial-direction fiber layer 21a and the first external non-axial-direction fiber layer 31a are preferably a peripheral-direction fiber layer, and the second internal non-axial-direction fiber layer 22a and the second external non-axial-direction fiber layer 32a are preferably a non-aligned fiber layer, particularly a peripheral direction fiber-containing nonwoven fabric layer. Also, for example, in a preferred embodiment shown in FIG. 3 described below, a fourth internal non-axial-direction fiber layer 24b is preferably a non-aligned fiber layer, particularly a peripheral direction fiber-containing nonwoven fabric layer. Also, for example, in a preferred embodiment shown in FIG. 4 described below, a fourth external non-axial-direction fiber layer 34c is a non-aligned fiber layer, particularly a peripheral direction fiber-containing nonwoven fabric layer. Note that the above arrangement of fiber layers in the hollow body is based on the assumption that the curable resin is not included.

(60) In particular, in the case where a peripheral direction fiber-containing nonwoven fabric layer, which is a non-aligned fiber layer, is disposed at a most peripheral surface of the hollow body, a nonwoven fabric layer of the peripheral direction fiber-containing nonwoven fabric layer is preferably disposed at a most peripheral surface of the hollow body. Specifically, concerning the peripheral direction fiber-containing nonwoven fabric layer, the internal non-axial-direction fiber layer 2 is more preferably used with a nonwoven fabric layer thereof being disposed at the innermost surface of the hollow body, and the external non-axial-direction fiber layer 3 is more preferably used with a nonwoven fabric layer thereof being disposed at the outermost surface of the hollow body. This is because reinforcing fibers of a peripheral-direction fiber layer adjacent thereto are allowed to be more easily aligned parallel to the peripheral direction, resulting in improvement in the design of the external appearance of the hollow body. For example, in FIG. 2, a peripheral direction fiber-containing nonwoven fabric layer as the second internal non-axial-direction fiber layer 22a is preferably used with the nonwoven fabric layer thereof being disposed at the innermost surface of the hollow body. A peripheral direction fiber-containing nonwoven fabric layer as the second external non-axial-direction fiber layer 32a is preferably used with the nonwoven fabric layer thereof being disposed at the outermost surface of the hollow body. Also, for example, in a preferred embodiment shown in FIG. 3 described below, a peripheral direction fiber-containing nonwoven fabric layer as the fourth internal non-axial-direction fiber layer 24b is preferably used with the nonwoven fabric layer thereof being disposed at the innermost surface of the hollow body. Also, for example, in a preferred embodiment shown in FIG. 4 described below, a peripheral direction fiber-containing nonwoven fabric layer as the fourth external non-axial-direction fiber layer 34c is preferably used with the nonwoven fabric layer thereof being disposed at the outermost surface of the hollow body.

(61) In the case where a peripheral direction fiber-containing nonwoven fabric layer, which is a non-aligned fiber layer, is disposed at a portion other than a most peripheral surface of the hollow body, the peripheral direction fiber-containing nonwoven fabric layer may be used with the nonwoven fabric layer thereof either facing the axial-direction fiber layer 1, or facing in an opposite direction from the axial-direction fiber layer 1.

(62) In addition, two or more non-aligned fiber layers may be successively disposed.

(63) In the case where a non-axial-direction fiber layer includes two or more peripheral-direction fiber layers, two or more of the peripheral-direction fiber layers may be successively disposed, or a non-aligned fiber layer may be provided between the peripheral-direction fiber layers.

(64) In the case where a non-axial-direction fiber layer contains one or more peripheral-direction fiber layers and one or more non-aligned fiber layers, the mass ratio of all the reinforcing fibers of the axial-direction fiber layer to all the reinforcing fibers of the peripheral-direction fiber layer(s) is typically 100:1-100:100, and in terms of the strength of the hollow body, preferably 100:10-100:100, more preferably 100:20-100:80, and even more preferably 100:30-100:70. All the reinforcing fibers of the peripheral-direction fiber layer(s) means all the reinforcing fibers of all peripheral-direction fiber layer(s) included in the hollow body. In the case where a peripheral direction fiber-containing nonwoven fabric layer is used as a non-aligned fiber layer, reinforcing fibers serving as peripheral direction fibers contained in the peripheral direction fiber-containing nonwoven fabric layer are also included.

(65) In a similar case, the mass ratio of all the reinforcing fibers of the axial-direction fiber layer to all the reinforcing fibers of the non-aligned fiber layer(s) is typically 100:10-100:100, and in terms of the strength of the hollow body, preferably 100:10-100:70, more preferably 100:20-100:50. All the reinforcing fibers of the non-aligned fiber layer(s) means all the reinforcing fibers contained in all non-aligned fiber layer(s) constituting the hollow body. In the case where a peripheral direction fiber-containing nonwoven fabric layer is used as a non-aligned fiber layer, reinforcing fibers constituting a nonwoven fabric layer contained in the peripheral direction fiber-containing nonwoven fabric layer are included, and reinforcing fibers serving as peripheral direction fibers of the peripheral direction fiber-containing nonwoven fabric layer are not included.

(66) Other embodiments in which a non-axial-direction fiber layer includes two or more fiber layers are shown in FIGS. 3 and 4. In terms of further improvement in the strength of the hollow body, the embodiment of FIG. 2 described above and an embodiment of FIG. 3 described below are preferable, more preferably the embodiment of FIG. 2.

Embodiment of FIG. 3

(67) FIG. 3 shows a hollow body 10b that has a vertical cross-section having a rectangular shape, and has an axial-direction fiber layer 1, a first internal non-axial-direction fiber layer 21b, a second internal non-axial-direction fiber layer 22b, a third internal non-axial-direction fiber layer 23b, and a fourth internal non-axial-direction fiber layer 24b that are provided on top of the internal side of the axial-direction fiber layer 1. In FIG. 3, the axial-direction fiber layer 1 is similar to one that has been described above. The first internal non-axial-direction fiber layer 21b, the second internal non-axial-direction fiber layer 22b, the third internal non-axial-direction fiber layer 23b, and the fourth internal non-axial-direction fiber layer 24b are each independently selected from a range similar to that of the non-axial-direction fiber layers 2 and 3 described above.

(68) In this embodiment, the second internal non-axial-direction fiber layer 22b and the third internal non-axial-direction fiber layer 23b are each independently preferably a peripheral-direction fiber layer.

(69) The first internal non-axial-direction fiber layer 21b is not particularly limited, and is, for example, a non-aligned fiber layer, particularly a peripheral direction fiber-containing nonwoven fabric layer.

(70) The fourth internal non-axial-direction fiber layer 24b is preferably a non-aligned fiber layer, particularly a peripheral direction fiber-containing nonwoven fabric layer.

(71) A peripheral direction fiber-containing nonwoven fabric layer as the first internal non-axial-direction fiber layer 21b may be used with the nonwoven fabric layer thereof being disposed in contact with the second internal non-axial-direction fiber layer 22b, or with the nonwoven fabric layer thereof being disposed in contact with the axial-direction fiber layer 1. A peripheral direction fiber-containing nonwoven fabric layer as the fourth internal non-axial-direction fiber layer 24b may be used with the nonwoven fabric layer thereof being disposed at the innermost surface of the hollow body, in terms of alignment of a peripheral-direction fiber layer as the third internal non-axial-direction fiber layer 23b.

(72) Also in this embodiment, at least one pair of end portions in the peripheral direction of the non-axial-direction fiber layer(s) overlap each other in the vertical cross-section. In terms of further improvement in the strength of the hollow body, the first internal non-axial-direction fiber layer 21b, the second internal non-axial-direction fiber layer 22b, and the third internal non-axial-direction fiber layer 23b each preferably is divided into four fiber layers in the peripheral direction of the hollow body with having end portions thereof being positioned at or near angled portions, as shown in FIG. 3. As a result, in each of the first internal non-axial-direction fiber layer 21b, the second internal non-axial-direction fiber layer 22b, and the third internal non-axial-direction fiber layer 23b, end portions in the peripheral direction of adjacent ones of the four fiber layers preferably overlap each other, and the resultant four overlap portions 4b are preferably positioned at or near angled portions.

(73) In this embodiment, the fourth internal non-axial-direction fiber layer 24b is preferably a single fiber layer, i.e., is not divided into two or more fiber layers in the peripheral direction of the hollow body, and end portions of the fiber layer 24b itself preferably overlap each other, in terms of use of the cavity of the hollow body for transport.

Embodiment of FIG. 4

(74) FIG. 4 shows a hollow body 10c that has a vertical cross-section having a rectangular shape, and has an axial-direction fiber layer 1, a first external non-axial-direction fiber layer 31c, a second external non-axial-direction fiber layer 32c, a the third external non-axial-direction fiber layer 33c, and a fourth external non-axial-direction fiber layer 34c that are provided on top of the external side of the axial-direction fiber layer 1. In FIG. 4, the axial-direction fiber layer 1 is similar to one that has been described above. The first external non-axial-direction fiber layer 31c, the second external non-axial-direction fiber layer 32c, the third external non-axial-direction fiber layer 33c, and the fourth external non-axial-direction fiber layer 34c are each independently selected from a range similar to that of the non-axial-direction fiber layers 2 and 3 described above.

(75) In this embodiment, the second external non-axial-direction fiber layer 32c and the third external non-axial-direction fiber layer 33c are each independently preferably a peripheral-direction fiber layer.

(76) The first external non-axial-direction fiber layer 31c is not particularly limited, and is, for example, a non-aligned fiber layer, particularly a peripheral direction fiber-containing nonwoven fabric layer.

(77) The fourth external non-axial-direction fiber layer 34c is preferably a non-aligned fiber layer, particularly a peripheral direction fiber-containing nonwoven fabric layer.

(78) A peripheral direction fiber-containing nonwoven fabric layer as the first external non-axial-direction fiber layer 31c may be used with the nonwoven fabric layer thereof being disposed in contact with the second external non-axial-direction fiber layer 32c, or the nonwoven fabric layer thereof being disposed in contact with the axial-direction fiber layer 1. A peripheral direction fiber-containing nonwoven fabric layer as the fourth external non-axial-direction fiber layer 34c is preferably used with the nonwoven fabric layer thereof being disposed at the outermost surface of the hollow body, in terms of alignment of a peripheral-direction fiber layer as the third external non-axial-direction fiber layer 33c.

(79) Also in this embodiment, at least one pair of end portions in the peripheral direction of the non-axial-direction fiber layer(s) overlap each other in the vertical cross-section. In terms of further improvement in the strength of the hollow body, the first external non-axial-direction fiber layer 31c, the second external non-axial-direction fiber layer 32c, the third external non-axial-direction fiber layer 33c, and the fourth external non-axial-direction fiber layer 34c each preferably is divided into four fiber layers in the peripheral direction of the hollow body with end portions thereof being positioned at or near angled portions, as shown in FIG. 4. As a result, in each of the first external non-axial-direction fiber layer 31c, the second external non-axial-direction fiber layer 32c, the third external non-axial-direction fiber layer 33c, and the fourth external non-axial-direction fiber layer 34c, end portions in the peripheral direction of adjacent ones of the four fiber layers preferably overlap each other, and the resultant four overlap portions 4b are preferably positioned at or near angled portions.

(80) (Other Materials)

(81) The hollow body of the present technology disclosed herein includes the above fiber layers, and in addition, a curable resin permeating the fiber layers. As the curable resin, any one that has been conventionally used in fiber-reinforced resin hollow bodies can be used. Specific examples of the curable resin include thermosetting resins, such as unsaturated polyester resins, epoxy resins, vinyl ester resins, and phenolic resins.

(82) The curable resin may contain an additive, such as a commonly used catalyst, release agent, pigment, shrinkage inhibitor, or silane coupling agent.

(83) (Dimensions)

(84) The hollow body of the present technology disclosed herein may have any suitable thickness, which may be determined, as appropriate, according to an application thereof. The hollow body of the present technology disclosed herein has a thickness of, for example, 1-20 mm, particularly 1-10 mm, and preferably 1-3 mm. The thickness of the hollow body refers to a wall thickness of the hollow body.

(85) The hollow body of the present technology disclosed herein may have any suitable outer perimeter, which may be determined, as appropriate, according to an application thereof. The hollow body of the present technology disclosed herein has an outer perimeter of, for example, 125-300 mm. The outer perimeter of the hollow body refers to an outer perimeter of the hollow body in a vertical cross-section thereof. In the case where the vertically cross-sectional shape of the hollow body is a rectangular shape, the length of one side thereof is not particularly limited, and is, for example, 45-75 mm. In the case where the vertically cross-sectional shape of the hollow body is a circular shape, the diameter thereof is not particularly limited, and is, for example, 45-75 mm.

(86) [Method for Manufacturing Fiber-Reinforced Resin Hollow Body]

(87) The fiber-reinforced resin hollow body of the present technology disclosed herein can be manufactured by pultrusion. In pultrusion, as specifically shown in FIG. 5, initially, reinforcing fibers 51 for constituting the axial-direction fiber layer 1 are impregnated with a curable resin 50. Next, the reinforcing fibers 51 impregnated with the curable resin joins a fiber sheet(s) (fiber layer) 52 for constituting the internal non-axial-direction fiber layer 2. Next, the reinforcing fibers 51 and the fiber sheets 52 join a fiber sheet(s) 53 for constituting the external non-axial-direction fiber layer 3. The number of the fiber sheets 52 is adjusted, as appropriate, according to the type and number of fiber layers constituting the internal non-axial-direction fiber layer 2. The number of the fiber sheets 53 is adjusted, as appropriate, according to the type and number of fiber layers constituting the external non-axial-direction fiber layer 3. Thereafter, these fibers and fiber sheets are guided by a guide 54 while being arranged such that a predetermined layered structure is obtained in the vertical cross-section. The fiber sheets 52 and the fiber sheets 53 are impregnated with the curable resin permeating the reinforcing fibers 51. The layered structure is pulled into a die 55 from one end thereof. At this time, the fiber sheets 52 and 53 are adjusted by the guide 54 such that end portions in the peripheral direction thereof overlap each other. In the die 55, the curable resin is sufficiently cured by heating to obtain the fiber-reinforced resin hollow body 10. The resultant fiber-reinforced resin hollow body 10 is continuously pulled out of the die 55 using a pulling device 56 (e.g., the double gripper technology), and is subjected to a subsequent process, such as cutting into a predetermined length using a cutter 57.

EXAMPLES

(88) Next, examples that were specifically carried out will be described.

(89) (Bending Test)

(90) A three-point bending test was carried out on specimens of fiber-reinforced resin hollow bodies according to examples and a comparative example using a procedure described below, to calculate the breaking load and flexural modulus of each specimen.

(91) Specifically, as shown in FIG. 7A, each specimen (fiber-reinforced resin hollow body) 10 having a length of 1400 mm described below was placed on a U-shaped flexure 61 having a support span k of 800 mm Thereafter, a load was applied to a center portion of the specimen 10 until it broke, using a testing jig 62 with a cover member (U-shaped jig) 11 being interposed between the specimen 10 and the testing jig 62, at a crosshead speed of 20 mm/min. The vertical deflection of the center portion to which the load was applied, i.e., the vertical deflection of the crosshead, and the value of the load, were measured. The breaking load and flexural modulus of the specimen was calculated from the vertical deflection and the load value. Note that FIGS. 7B and 7C are cross-sectional views taken along B-B and C-C, respectively, of FIG. 7A.

(92) The cover member 11 was made of steel, and had a thickness (t1=t2=t3) (see FIG. 7B) of 10 mm, a cover depth (h1=h2) (see FIG. 7B) of 38.8 mm, and an axial direction length (j) (see FIG. 7A) of 100 mm. The specimen 10 was not joined to the cover member 11 using a bolt or the like.

(93) Note that the bending test was carried out on lots of four specimens having the same configuration. After the breaking loads of each lot were calculated, the average of the four calculated values of each lot was calculated, and the average value was regarded as the breaking load of each specimen. This is true of the flexural modulus of each specimen.

(94) (Specimens)

(95) Hollow body specimens of the examples and comparative example were prepared using the above method for manufacturing the fiber-reinforced resin hollow body. FIG. 8 shows the shapes and dimensions of the specimens. Note that the unit of the numerical values in FIG. 8 is “mm.”

(96) FIG. 9 shows materials used in the specimens of the examples and comparative example.

(97) Table 1, Table 2, FIGS. 10A-10D, FIG. 11, and FIG. 12 show the configurations of specimens D-1, D-2, D-3, and D-4 of Examples 1-3 and Comparative Example 1, and their breaking loads and flexural moduli resulting from the bending test.

(98) TABLE-US-00001 TABLE 1 Comparative Example 1 Example 1 Example 2 Example 3 Specimen (D-1) (D-2) (D-3) (D-4) Layered Internal First layer Single stitched cord-fabric mat layer (mat layer structure non-axial Q1 disposed at innermost surface) direction Second layer Single S2 cord fabric layer fabric layer Q2 Axial direction fabric Rovings layer Q3 External First layer Single S2 cord fabric layer non-axial Q4 direction Second layer Single stitched cord-fabric mat layer (mat layer fabric layer Q5 disposed at outermost surface) Cross-sectional view of FIG. 10A FIG. 10B FIG. 10C FIG. 10D molded article

(99) TABLE-US-00002 TABLE 2 Material proportions Flexural Amounts of glass fibers (g/m) Mass of Length of Mass of Mass per Breaking modulus Peripheral Axial Random resin product product unit load (N) (GPa) Specimens direction direction directions Total (g/m) (mm) (kg) (kg/m) Average Average Comparative 209.3 549.2 164.4 922.9 337.1 1402 1.76 1.26 8594 24.33 Example 1 (D-1) Example 1 229.2 549.2 180.0 958.4 311.6 1.78 1.27 10132 25.49 (D-2) Example 2 233.4 549.2 166.8 949.4 320.6 10966 25.39 (D-3) Example 3 239.2 549.2 180.0 968.4 301.6 1402 1.78 1.27 11027 26.20 (D-4)

(100) As shown in Table 2 and FIGS. 11 and 12, the specimens D-2-D-4 of Examples 1-3 having overlap portions had both a good breaking load and flexural modulus compared to the specimen D-1 of Comparative Example 1 having no overlap portion.

(101) Concerning the value of the breaking load, comparison between the specimens D-2-D-4 of Examples 1-3 demonstrates that Example 2 (D-3) and Example 3 (D-4) in which all pairs of end portions had an overlap portion had further better results than those of the specimen D-2 of Example 1 having overlap portions only in a lower portion thereof. Example 3 (D-4) in which a single fiber layer was disposed at the innermost surface had a slightly better result than that of Example 2 (D-3) in which the innermost surface had overlap portions at the four corners thereof. Note that, concerning the flexural modulus, Example 1 (D-2) and Example 2 (D-3) had almost the same value, and Example 3 (D-4) had a slightly better value than those of Examples 1 and 2.

(102) Next, specimens having configurations shown in Tables 3 and 4 were prepared for the fiber-reinforced resin hollow bodies 10 of FIGS. 2-4. The above bending test was carried out on the specimens. As a result, breaking loads and flexural moduli shown in Table 4 were obtained.

(103) TABLE-US-00003 TABLE 3 Specimen Example 4 Example 5 Example 6 Layered structure Internal non-axial — 24b: composite layer A (mat layer — direction fabric layer disposed at innermost surface) 23b: cord-fabric layer A 22a: composite layer A (mat layer 22b: cord-fabric layer A disposed at innermost surface 21a: cord-fabric layer A 21b: composite layer A (mat layer facing roving layer A) Axial direction fabric 1: roving layer A layer External non-axial 31a: cord-fabric layer A — 31c: composite layer A (mat direction fabric layer layer facing roving layer A) 32a: composite layer A (mat layer 32c: cord-fabric layer A disposed at outermost surface) — 33c: cord-fabric layer A 34c: composite layer A (mat layer disposed at outermost surface) Cross-sectional view of FIG. 2 FIG. 3 FIG. 4 molded article

(104) TABLE-US-00004 TABLE 4 Material proportions Flexural Amounts of glass fibers (g/m) Mass of Length of Mass of Mass per Breaking modulus Peripheral Axial Random resin product product unit load (N) (GPa) Specimens direction direction directions Total (g/m) (mm) (kg) (kg/m) Average Average Example 4 239.2 488.0 180.0 907.0 312.8 1403 1.72 1.23 12170 22.69 Example 5 10360 19.67 Example 6 1.71 1.22 8390 22.58

(105) In Table 3, a composite layer A included only a single “stitched cord-fabric mat” layer shown in FIG. 9, and the mat layer was disposed as indicated in Table 3. A cord-fabric layer A included only a single “S2 cord-fabric” layer shown in FIG. 9. A roving layer A included a “roving” shown in FIG. 9. Note that, as shown in Table 4, specimens of Examples 4-6 contained materials at proportions different from those of Examples 1-3 and Comparative Example 1 shown in Table 2.

(106) In the specimen of Example 4, a non-axial-direction fiber layer was provided on both the internal and external sides of an axial-direction fiber layer. In the specimens of Examples 5 and 6, a non-axial-direction fiber layer was provided on only one of the internal and external sides of an axial-direction fiber layer. It was found that the specimen of Example 4 had both a good breaking load and flexural modulus compared to the specimens of Examples 5 and 6.

(107) As described above, the present technology disclosed herein can provide a fiber-reinforced resin hollow body having a sufficiently high strength.

INDUSTRIAL APPLICABILITY

(108) The fiber-reinforced resin hollow body of the present technology disclosed herein is useful as various members for use in a variety of fields, such as the fluid transport field, architecture field, and automotive field. The fiber-reinforced resin hollow body of the present technology disclosed herein is particularly useful as a member for directly or indirectly supporting and fixing an automotive instrument panel. Examples of such a member include, in the automotive field, cross-car beams, center members, brake pedal rearward displacement preventing brackets, cowl brackets, steering bracket uppers, and steering bracket lowers.

DESCRIPTION OF REFERENCE CHARACTERS

(109) 1 AXIAL-DIRECTION FIBER LAYER 2 NON-AXIAL-DIRECTION FIBER LAYER 3 NON-AXIAL-DIRECTION FIBER LAYER 4a, 4b OVERLAP PORTION 10, 10a, 10b, 10c FIBER-REINFORCED RESIN HOLLOW BODY 21a, 21b FIRST INTERNAL NON-AXIAL-DIRECTION FIBER LAYER 22a, 22b SECOND INTERNAL NON-AXIAL-DIRECTION FIBER LAYER 23b THIRD INTERNAL NON-AXIAL-DIRECTION FIBER LAYER 24b FOURTH INTERNAL NON-AXIAL-DIRECTION FIBER LAYER 31a, 31c FIRST EXTERNAL NON-AXIAL-DIRECTION FIBER LAYER 32a, 32c SECOND EXTERNAL NON-AXIAL-DIRECTION FIBER LAYER 33c THIRD EXTERNAL NON-AXIAL-DIRECTION FIBER LAYER 34c FOURTH EXTERNAL NON-AXIAL-DIRECTION FIBER LAYER