JP2010053479A - Fiber-reinforced woven cloth and radome using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radome having excellent electric and mechanical properties by using a fiber-reinforced woven cloth that has high adhesion and shear strength and is easy to mechanically process, since when a low-dielectric-constant fiber such as an olefin fiber is used as a reinforcing fiber for FRP of radome, the olefin fiber has difficulty in mechanical processing because the olefin fiber has low adhesion to a matrix resin, easily causes a slippage, has low shear strength and high strength. <P>SOLUTION: An olefin fiber and a glass fiber are used as warp or weft and subjected to mixed weaving so as to make the glass fiber appear at least on one side of the woven cloth. Cloths including at least one fiber-reinforced woven cloth subjected to mixed weaving are piled so that a surface in which the glass fiber mainly appears is stuck close to a matrix resin and laminated along a mold of radome. The laminate is impregnated with the matrix resin and integrated to manufacture the radome. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

FRP (fiber reinforced resin) used for structural parts such as radomes that house radio wave devices such as antennas that transmit and receive radio waves and protect them from the external environment (wind, rain, snow, sand, ice, sunlight, etc.) ). FRP (fiber reinforced resin) is a resin reinforced by laminating a woven fabric having excellent electrical and mechanical properties and impregnating with a matrix resin. Such radomes are mainly used for aircraft, vehicles, ships and the like as communication and radar devices.

The radome must have a strength necessary to protect the radio wave device from the external environment without interfering with radio waves transmitted and received by the radio wave device housed therein. As a conventional radome having such characteristics, a core made of a low-density dielectric material such as a foam is provided between a first composite material surface plate having a fiber reinforced resin and a second opposing composite material surface plate. There is a thing using the sandwich structure board which sandwiched. By sandwiching a low-density dielectric, such a sandwich structure plate can reduce the overall dielectric constant and improve the radio wave permeability of the radome while maintaining the structural strength. Although glass fiber is generally used as the reinforcing fiber, it is also known to further reduce the dielectric constant by using a fiber having a low dielectric constant such as polyester-polyarylate fiber (for example, patent document). 1).

In addition, as shown in Patent Document 2, the Company applied for a patent for “radome and its manufacturing method”. In this patent, first, a glass fiber woven fabric is disposed on the inner side of the radome with respect to the olefin fiber woven fabric, and is laminated along a mold. Next, while the inside of the mold is in a vacuum state, the matrix resin is injected into the mold and cured to form an integrated FRP to produce a radome.
As a result, it is possible to manufacture a radome having excellent electrical and mechanical properties while ensuring high strength with a glass woven fabric while ensuring radio wave transmission with an olefin woven fabric having a low dielectric constant.
Special table 2007-519298 (page 1-12, Fig. 1) Japanese Patent Application No. 2007-316821 (page 1-13, Fig. 1)

However, when organic fibers with a low dielectric constant such as olefin fibers are used as reinforcing fibers, the adhesive strength with the matrix resin is weak, and slipping occurs easily when stress is generated at the interface between the olefin woven fabric and the matrix resin. It turned out that. For this reason, corona discharge treatment was performed on the surface of the olefin woven fabric, and the adhesion could be improved a little, but it was insufficient.
In addition, since the olefin fiber has high strength, it is difficult to perform machining such as drilling with a normal drill.

In order to solve this problem, the present invention uses olefin fibers and glass fibers as warp yarns or weft yarns, and interwoven so that the glass fibers mainly appear on at least one side (weave different fibers as warp yarns and weft yarns). At least one woven fabric that has been interwoven is included and stacked so that the surfaces on which the glass fibers mainly appear are in close contact with each other, and are stacked along the shape of the radome. The laminate is impregnated with a matrix resin and cured to produce a radome.

The present invention is a fiber excellent in electrical and mechanical properties by securing the strength required by glass fiber while ensuring the radio wave transmission required by radome by olefin fiber by interweaving olefin fiber and glass fiber. Reinforced woven fabric can be provided.
Further, since the glass fiber excellent in adhesion to the matrix resin appears mainly on at least one surface of the woven fabric, no slip occurs at the interface with the matrix resin, and the shear strength is improved.
Thirdly, since the woven fabric made only of olefin fibers has high strength, it is difficult to machine. However, it became possible to machine by interweaving olefin fiber and glass fiber.
Fourth, olefin fibers are very light with a density of only 38% of glass fibers (see FIG. 2). Therefore, there is an effect that the weight can be reduced by weaving many olefin fibers.

Embodiment 1 FIG.
FIG. 1 is an explanatory diagram of a radome 1 according to this embodiment. In FIG. 1, a radome 1 is fixed to a pedestal 2 with fixing bolts 4, and a radio wave device 3 including an antenna is housed inside the radome 1. The radome 1 protects the radio wave device 3 from the external environment (for example, natural environments such as wind, sunlight, rain, and seawater, impacts from outside, and dust) and transmits radio waves between the outside and the radio wave device 3. When transmitting and receiving, radio waves are transmitted.

Here, the shape of the radome 1 needs to prevent the radome 1 and the radio wave device 3 from interfering when the radio wave device 3 is movable. The radome 1 is shaped such that the distance from the center of the radio wave device 3 to the radome 1 is as equal as possible to the radio wave output direction of the radio wave device 3 and the radio wave is incident on the radome 1 perpendicularly. .
Further, in order to easily transmit radio waves through the radome 1, it is necessary to use a material having a low dielectric constant and a low dielectric loss. FIG. 2 shows mechanical and electrical characteristic values of olefin fiber (Dyneema) and glass fiber, which are fibers used for FRP in the present invention.
Dyneema is a trade name commercially available from Toyobo Co., Ltd. Among olefin fibers, it is called an ultra high molecular weight polyethylene fiber, and is an excellent fiber having a low dielectric constant, a high elastic modulus, a high strength and a light weight. E-glass is a common glass fiber manufactured by Nitto Boseki Co., Ltd. NE-glass is also a glass fiber with a low dielectric constant, manufactured by Nitto Boseki Co.

FIG. 3 is a schematic cross-sectional view of a warp double woven fabric 5 as a typical example of the woven fabric used in the present embodiment. In the figure, glass fiber is used for the warp yarn 6 and the back warp yarn 8, and olefin fiber is used for the weft yarn 7. As a result, since glass fibers mainly appear on both the front and back surfaces, the olefin fibers that are the weft yarns 7 are almost covered with the glass fibers on both the front and back surfaces. Accordingly, the glass fibers are always in close contact with the interface with the matrix resin to be impregnated.
Since the glass fiber has good adhesion to the matrix resin, the resin reinforced by the main woven fabric has no shear and high shear strength unlike the olefin woven fabric which easily slips and has low shear strength. In addition, since the olefin fiber covered with glass fiber has a low dielectric constant and low dielectric loss, the radio wave transmission is good and the characteristics of the radome are improved.

If the thickness is the same, the blending ratio of the olefin fiber and the glass fiber is about 1: 2. However, in order to improve the radio wave transmittance, the weft yarn 6 is manufactured by increasing the blending ratio of the olefin fibers by increasing the number of twisted olefin fibers. In the case of improving the mechanical strength, it can be similarly controlled by increasing the blending ratio of the glass fibers.

FIG. 4 shows an example of a radome cross-sectional structure diagram. For example, two layers of the double woven fabric 9 are laminated along the shape of the radome 1. The laminate is impregnated with a matrix resin 10 and cured to produce a radome 1. 11 is a radome outer surface, and 12 is a radome inner surface.

As the olefin fiber, ultra high molecular weight polyethylene fiber is used. With this fiber, the excellent tensile strength and elastic modulus can be reflected in the characteristics of the radome 1. As the ultrahigh molecular weight polyethylene fiber, for example, Dyneema (relative permittivity: 2.2, molecular weight: 4 million) commercially available from Toyobo Co., Ltd. can be used.

As an example of the glass fiber used in the present embodiment, NE-glass (manufactured by Nitto Boseki Co., Ltd., relative dielectric constant: 4.7) which is a low dielectric property glass fiber can be given. Moreover, since glass fiber generally has many hydroxyl groups and surface treatment such as coupling agent treatment is easy to improve adhesion to the matrix resin 7, E-glass, D-glass Glass fibers such as T-glass can also be used.

The matrix resin 10 is preferably a liquid thermosetting resin capable of ensuring impregnation properties in an uncured state in consideration of manufacturability of the radome 1. Moreover, what has a high density of hydroxyl groups after hardening and forms a hydrogen bond easily is preferable. Examples of such matrix resin 10 include epoxy resin, vinyl ester resin, unsaturated polyester resin, and silicone resin.
The curing agent for the matrix resin 10 is not particularly limited, and those known in the technical field can be used. Examples of such curing agents include organic oxides and acid anhydrides. Further, the blending amount of the curing agent is not particularly limited.

In this embodiment, by interweaving olefin fiber and glass fiber, while ensuring radio wave permeability required as a radome by olefin fiber, it ensures the strength required by glass fiber, and has excellent electrical and mechanical properties. FRP can be provided.
Secondly, since glass fibers excellent in adhesion to the matrix resin 10 mainly appear on both sides of the woven fabric, slip does not occur at the interface with the matrix resin, and the shear strength is improved. To do.
Thirdly, since the woven fabric made only of olefin fibers has high strength, it is difficult to machine. However, it became possible to machine by interweaving olefin fiber and glass fiber.
Fourth, olefin fibers are very light with a density of only 38% of glass fibers (see Table 1). Therefore, there exists an effect which can be reduced in weight by using many olefin fibers.
Embodiment 2. FIG.

FIG. 5 shows an example of satin weaving as a second embodiment. The satin weave is composed of 5 or more warps and wefts, and the complete structure is made. The intersections are arranged at regular intervals and not adjacent to each other. It is a structure in which either the warp or the weft is very little floating, and only the warp or the weft appears to appear mainly.
When weft weaving with olefin fiber as weft 13 and glass fiber as warp 14, a surface where glass fiber mainly appears and a surface where mainly olefin fiber appears are formed. Since the glass fiber has good adhesion to the matrix resin, it is necessary to laminate it with another layer in a state where the surface on which the glass fiber appears mainly is in close contact.
In addition, as long as the glass fiber appears on one side (texture) (texture), it is also possible to use oblique weave, warp double weave, weft double weave, warp double weave, and other structures.

Next, a method for laminating the woven fabric will be described using the cross-sectional structure of the radome shown in FIG.
The two satin woven fabrics and the one glass fiber woven fabric are laminated so that the surfaces on which the glass fibers mainly appear are closely adhered. That is, the glass fiber woven fabric 17 is located in the center, and the satin weave woven fabrics 15 and 16 are laminated on both sides thereof with the surfaces 15a and 16a on which the glass fibers mainly appear adhered to each other. When laminated in this manner, the glass fiber has good adhesion to the matrix resin, so that slip does not occur at the interface with the matrix resin and the shear strength is improved.
If the required strength can be obtained, the glass fiber woven fabric can be removed.
Alternatively, the warp double woven fabric of the first embodiment can be used instead of the glass fiber woven fabric.

FIG. 7 shows a schematic cross section of a warp double weave 18 as another example of the first embodiment.
Both the warp yarn 19a and the weft yarn 19b are plain woven using olefin fibers, and the back woven fabric 20 is plain woven using both the warp yarn 20a and the weft yarn 20b using glass fibers. However, a part of the back warp yarn 20a is hung on the front weft yarn 19b to join the front woven fabric 19 and the back woven fabric 20, the surface is covered with olefin fibers, and the back surface is covered with glass fibers. Therefore, since this is a weaving method in which glass fibers mainly appear on one side, this structure may be used.

In this Embodiment 2, since it comprised so that many (about half) olefin fibers might be included, as a woven fabric which interwoven, radio wave permeability is favorable and weight reduction can also be performed.
Further, compared with the warp double weave used in the first embodiment, since a general simple structure (eg, satin weave) is used, it can be easily manufactured.
Embodiment 3 FIG.

It is also possible to superimpose an olefin fiber woven fabric as a front fabric and a glass fiber woven fabric as a back fabric and sew together using glass fiber threads so that the two woven fabrics do not slip.
For this, since a woven fabric made of only olefin fibers and a woven fabric made of only glass fibers are used, there is no need to interweave and it can be manufactured by a relatively simple sewing operation. Further, slip at the interface between the olefin fiber and the matrix resin 10 can be eliminated, and the shear strength can be improved.

Radome explanatory drawing which shows Embodiment 1 of this invention Dyneema showing the first embodiment of the present invention, mechanical and electrical characteristic values of glass fiber 1 is a schematic cross-sectional view of a warp double woven fabric showing Embodiment 1 of the present invention. Sectional structure of radome showing Embodiment 1 of the present invention Schematic structural diagram of satin weaving woven fabric showing Embodiment 2 of the present invention Sectional structure of radome showing embodiment 2 of the present invention Schematic sectional view of a warp double weave woven fabric showing Embodiment 2 of the present invention

Explanation of symbols

1 radome, 2 pedestals, 3 radio wave equipment, 4 fixing bolts, 5 vertical double woven fabric,
6 warp yarn (glass fiber), 7 weft yarn (olefin fiber),
8 Back warp yarn (glass fiber), 9 Warp double woven fabric, 10 Matrix resin,
11 radome outer surface, 12 radome inner surface,
13 weft yarn (olefin fiber), 14 warp yarn (glass fiber),
15 satin weaving woven fabric, 15a satin weaving weaving surface 15 on which glass fiber mainly appears,
16 satin weaving woven fabric, 16a surface of satin weaving weaving fabric 16 on which glass fiber mainly appears,
17 Glass fiber woven fabric, 18 Vertical woven fabric,
19 front woven fabric (olefin fiber), 20 back woven fabric (glass fiber),
19a Front warp yarn (olefin fiber), 19b Front weft yarn (olefin fiber),
20a Back warp yarn (glass fiber), 20b Back weft yarn (glass fiber).

Claims (7)

A fiber-reinforced woven fabric characterized by cross-weaving olefin fiber and glass fiber as warp or weft. A fiber-reinforced woven fabric, wherein the glass fibers are warps on the front and back surfaces, the olefin fibers are wefts, and are interwoven so that the glass fibers mainly appear on both the front and back surfaces. A fiber-reinforced woven fabric, which is interwoven so as to have a surface on which the olefin fiber mainly appears and a surface on which the glass fiber mainly appears. A fiber-reinforced woven fabric, wherein a surface fabric of the olefin fiber woven fabric and a backing fabric of the glass fiber woven fabric are stitched together using the yarn of the glass fiber. The fiber-reinforced woven fabric according to any one of claims 1 to 4, wherein the olefin fiber is an ultrahigh molecular weight polyethylene fiber. The fiber-reinforced woven fabric according to any one of claims 1 to 4, wherein the glass fiber is a low dielectric constant glass fiber. A fiber comprising at least one fiber-reinforced woven fabric according to any one of claims 1 to 6 and impregnated with a matrix resin in a laminate in which glass fibers are mainly brought into close contact with each other and stacked. A radome characterized by using reinforced resin as a structural material.

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