JP2004099731A - Packed resin body for producing fiber-reinforced composite material and method for producing fiber-reinforced composite material using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a packed resin body in which an uncured resin for RFI (resin film infusion) molding having difficulty in film formation is subjected to RFI molding, and to provide a method for producing a fiber-reinforced composite material using the obtained packed resin body for RFI molding. <P>SOLUTION: In RFI molding, though the uncured resin film 5, which is impregnated into a reinforcing fiber or fiber woven fabric to give the matrix of a composite material, is formed into a film, the film is brittle and has weak strength and is packed into a baggy supporter composed of polyimide films 3 and 4. Since a great number of holes 7 are bored through at least one polyimide film 3, the uncured resin film 5 melted by rise in temperature flows out. The uncured resin film 5 having rigidity and difficulty in film formation is readily handled by packing/retaining the uncured resin film in the supporter 2 and is held in a fixed position/distribution. <P>COPYRIGHT: (C)2004,JPO

Description

【００２１】
未硬化樹脂フィルム５は、２枚のポリイミドフィルム３，４間に充填の後、融着フィルムによってポリイミドフィルム３，４の周囲部を融着して融着部６とすることにより、未硬化樹脂フィルム５を充填した内部が封止されている。ここで、一方のポリイミドフィルム３には、直径φ１ｍｍの孔７（一部にのみ符号を付す）が４ｍｍ間隔に穿けられている。孔径が小さいと、未硬化樹脂フィルム４を溶融したときの溶融樹脂の流れを阻害する。また、逆に孔径が大きすぎると、未硬化樹脂フィルム５にクラックが生じて細かく砕けた場合に、未硬化樹脂フィルム４の破片の脱落が生じるので、ポリイミドフィルム３，４の孔径および孔数については、十分な配慮が必要である。
【００２２】
樹脂充填体１の具体的な製作手順は下記の通りである。実施例１〜４では、表１の未硬化樹脂成形方法の欄に記してあるように、未硬化樹脂フィルムを粉末プレス成形によって成形した例である。まず、ポリアミック酸の熱イミド化反応によって得られたユーピレックスＡＤのイミドオリゴマー粉末を粉砕・分級して、平均粒径を約３０μｍ以下とした。このようにして得られた粉末を、プレス金型を用いて２００ｍｍ×２００ｍｍのフィルム状に成形した。このようにして成形された未硬化樹脂フィルム５を減圧下でポリイミドフィルム３，４中に真空パックし、ポリイミド融着フィルムを用いてポリイミドフィルム３，４の周囲部を融着して融着部６とし、樹脂充填体１を製作した。ポリイミドフィルム３，４を除いた樹脂フィルム部である未硬化樹脂フィルム５の厚さは、表１に示す通り、０．９４ｍｍ、１．８８ｍｍ、３．７５ｍｍである。
【００２３】
一方、実施例５〜８は、表１の未硬化樹脂成形方法の欄に記してあるように、未硬化樹脂フィルムをイミドオリゴマーの溶融成形によって製作した例である。熱イミド化が終了したユーピレックスＡＤのイミドオリゴマーを３００℃で溶融後これを金型に充填し、わずかに圧力をかけながら金型内で徐冷して、２００ｍｍ×２００ｍｍの平板状フィルムを得た。このようにして得られた未硬化樹脂フィルム５を、減圧下でポリイミドフィルム３，４中に真空パックし、ポリイミド融着フィルムを用いてポリイミドフィルム３，４を融着して樹脂充填体１を製作した。ポリイミドフィルム３，４を除いた未硬化樹脂フィルム５の厚さは、表１に示す通り、０．６８ｍｍ、１．３６ｍｍ、２．７３ｍｍである。いずれも、後述する複合材を製作するために必要なフィルムの面密度から、面密度が同じになるようにフィルム厚さを決定したため、粉末プレス法で成形された実施例１〜４の方が、溶融成形法で成形された実施例５〜８よりも厚くなった。なお、比較例１及び２は、それぞれ粉末プレス成形又は溶融成形によってフィルム化したイミドオリゴマーである。
【００２４】
試作した樹脂充填体１の外観検査結果が表１の最右欄に示されている。まず、比較例１においては、未硬化樹脂フィルムに割れが生じ、樹脂充填体の成形は不可能であった。また、比較例２ではかろうじて未硬化樹脂フィルムが成形できたものの、これをハンドリング中に割れが発生し、ＲＦＩ成形用フィルムに適用することは、全く不適であることがわかった。一方、本発明による実施例においては、厚さが薄い場合には、パックされた未硬化樹脂フィルム５に割れなどは認められず、外観上良好な樹脂充填体１が得られた。しかしながら、実施例１〜４のプレス成形品、実施例５〜８の溶融成形品ともに、未硬化樹脂フィルム５の厚さが厚くなる（フィルム樹脂部分厚さの欄で３．７５ｍｍ又は２．７３ｍｍ）と、成形された未硬化樹脂フィルム５の一部に割れ（クラック）が観察された。樹脂を保持するポリイミドフィルム３，４が１００μｍ（樹脂保持用フィルムのフィルム仕様の欄）と厚い方が未硬化樹脂フィルム５の割れを抑制できる傾向が認められたが、逆に未硬化樹脂フィルム５の柔軟性は低下した。しかしながら、本発明による実施例においては、充填された未硬化樹脂フィルム５中にクラックが発生しても、これをポリイミドフィルム３，４の中にパッキングした樹脂充填体１としての形状保持性には全く問題はなく、ＲＦＩ成形に十分適用可能な形状保持性を有していることがわかった。
【００２５】
表１中の実施例９は、未硬化樹脂フィルム５の形状保持性を向上させた例である。図２は、実施例９に係る樹脂充填体の例を示す模式図である。実施例９に係る樹脂充填体１０は、図２に示すように、溶融成形によって製作された未硬化樹脂フィルム５を２００×２００ｍｍのサイズの区画１２に区画化し、保持体１１を構成するポリイミドフィルム３，４を各区画１２間において融着部６と同様の融着部１３によって融着して、全体として８００ｍｍ×８００ｍｍサイズに作製されている。このように、樹脂充填体１０の寸法が大きくなった場合には、樹脂充填体としての形状保持可能な大きさの複数の区画１２に分割して未硬化樹脂フィルム５をパッキングすることで形状保持性を向上させることにより、サイズ拡大化にも対応可能である。
【００２６】
表１中の実施例１０は、溶融成形によって得られたイミドオリゴマーから成る未硬化樹脂フィルム５をポリイミドフィルム３，４間にパッキングする際に、上下２枚のポリイミドフィルム３，４の端部を融着する代わりに、エポキシ樹脂系接着剤を用いて接着した樹脂充填体を示す。使用した接着剤は２００℃を越えると急激に強度が低下するため、未硬化樹脂フィルム５が溶融する温度（約２９０℃以上）ではポリイミドフィルム３，４の接着端部の接着力が急減し、封止力が低下した端部から溶融した未硬化樹脂を押し出す（又は吸い出し）によって容易に流出させることができる。この方法では、図１に示したような孔７をポリイミドフィルム３に穿ける必要がないという利点がある。
【００２７】
（実施例１１〜１３）
表２に示す実施例１１〜１３は、本発明によって得られたＲＦＩ成形用の樹脂充填体１を用いてＲＦＩ法による複合材平板の製造を行った例である。使用した強化材は、東レ（株）製の高強度炭素繊維Ｔ８００ＨＢ−６Ｋを強化繊維とする５枚朱子織物（織物目付は３１２ｇ／ｍ^２　）である。図３は、複合材平板をＲＦＩ成形する際の製造工程を示す模式図である。まず、金型２０の下型２１内に１６０×１６０ｍｍに裁断した炭素繊維織物を所定の枚数（８枚又は１６枚）積層してドライプリフォーム２５とした。この上に、実施例１に示した本発明による樹脂充填体１を、孔７が穿けられたポリイミドフィルム３が下側になるように設置した。織物１枚あたりの目標厚さを０．３ｍｍとし、積層枚数に対応した目標板厚（２．４ｍｍ又は４．８ｍｍ）を設定した。これらの実施例では、計算上の繊維体積率は約５８％である。
【表２】

【００２８】
図４は、実施例１１〜１３における複合材のグラフ化された成形プログラムである。成形工程中、金型２０内はロータリーポンプ２４を用いて常に減圧されている。未硬化樹脂であるユーピレックスＡＤ（分子量１６００バージョン）は、約２８０℃から溶融を開始し、３００℃で炭素繊維織物への含浸には十分な粘度（１０Ｐａ・ｓ）まで低下する。そこで３００℃に達してから徐々に金型２０の加圧（上型２２の加圧）を開始し、下型２１と上型２２との間に形成されるキャビティ２３内において、プリフォーム２５中へのポリイミド樹脂の含浸を行った。最大型締め圧１０ｔｏｎを負荷した状態で、更に温度を３７０℃まで昇温し、１時間保持することによってポリイミド樹脂（未硬化樹脂）を硬化させて複合材を成形した。実施例１１〜１３ともに、ポリイミド樹脂の含浸は良好であり、超音波探傷では欠陥は検出されなかった。また、製造した複合材平板から無孔圧縮試験片を切りだして圧縮強度を測定した結果も良好であった。
【００２９】
しかしながら、実施例１２のように、複合材の板厚が厚くなり、樹脂充填体１の厚さが増すとポリイミド樹脂が流出後の樹脂充填体１にシワが発生し、これが複合材表面に転写されるので、表面の平滑性が損なわれる。板厚が厚い場合には、実施例１３のように、プリフォーム２５の上下両側に樹脂充填体１，１を配置することによって各樹脂充填体１の厚さを薄くし、樹脂流出後の樹脂充填体１に発生するシワを抑制することが効果的である。
【００３０】
実施例１４は、本発明によるＲＦＩ成形用の樹脂充填体１を用いたＲＦＩ成形によって、補強構造を有する平板を一体成形した例である。図５は、本発明における強化繊維複合材料の製造方法によって、実施例１４に示す補強構造を有する平板の製作方法の一例を示す模式図である。実施例１４では、樹脂充填体１が相対的に厚く、また小さいため、孔７穿きフィルムではなく、実施例１０で示した接着剤による封止構造を採用したタイプの樹脂フィルムを用いた。金型３０は、図３に示した金型２０と同様に、下型３１、下型３１と共にキャビティ３３を形成する上型３２、キャビティ３３内のエアを吸引排気して負圧にするロータリーポンプ３４を備えている。上型３２は、プリフォーム３５の補強用の突起部３６を有する形状に合わせて、穴部３７が形成されている。補強構造を有する複合材の成形プログラムは、図４に示すプログラムと同様である。成形された補強平板は、超音波探傷の結果では特に欠陥は認められず、良好な結果が得られた。このように、本発明における樹脂充填体１を用いることによって、複雑な形状の複合材製品であっても容易に製造することが可能である。
【００３１】
（実施例１５）
実施例１５は、保持体を構成する柔軟な多孔質体の開気孔部に複合材のマトリクスとなる樹脂が充填された樹脂充填体の例である。多孔質体としては、多孔質ポリイミド（宇部興産（株）製ユーピレックスフォームＢＦ３０１、密度０．０１ｇ／ｃｍ^３　）を使用した。具体的な製作手順は下記の通りである。まず、ユーピレックスＡＤ（分子量約１６００）を３００℃で加熱溶融し、真空含浸法によって厚さ３ｍｍのユーピレックスフォームの開気孔部に充填させた。ユーピレックスフォームは発泡材ではあるが、壁厚が薄いため、ほとんどが外部に向かって開いた開気孔部となっており、樹脂の充填は良好であった。得られた樹脂充填体は、実施例１〜１０に示した樹脂充填体１と異なり、柔軟性には劣るが、含浸された未硬化樹脂の脱落はほとんどなく、ＲＦＩ成形の樹脂充填体として十分に使用可能であった。多孔質体は形状加工が容易であるため、複雑形状の複合材を製造する際に必要となる複雑形状の樹脂充填体を容易に製作できるという利点がある。図６に示す顕微鏡写真には、複合材のマトリクスとなる樹脂が充填される開気孔部が形成されている樹脂充填体の表面が撮影されている。
【００３２】
【発明の効果】
以上説明したように、本発明の繊維強化複合材料製造用の樹脂充填体によれば、強化繊維又は繊維織物に含浸されたときに複合材のマトリクスとなる未硬化樹脂を保持体内に充填させて成り、保持体は温度上昇によって溶融した未硬化樹脂を外部に流出可能であることから成っているので、従来は脆く強度の弱くフィルム化が不可能である未硬化樹脂に対しても、所定の位置に未硬化樹脂を保持することができ、未硬化樹脂が砕けたり破損すること等に気遣うことなく、取扱が非常に容易になる。また、未硬化樹脂のプリフォームに対する位置や分布も所定の位置や分布に維持することができる。上記の樹脂充填体のサイズが大きくなった場合には、樹脂充填体をいくつかの区画に分割し、かつ各区画間の２枚のフィルムを接着又は融着することにより、樹脂充填体の強度及び柔軟性を向上させることができる。更に、柔軟な多孔質体の開気孔部に複合材のマトリクスとなる樹脂を充填することにより、従来は未硬化樹脂のフィルム化が不可能である樹脂に対しても、また形状が複雑なプリフォームに対してもＲＦＩ法による複合材料の製造を提供することができる。
【００３３】
また、この発明による繊維強化複合材料の製造方法によれば、複合材料の強化繊維又は繊維織物と、保持体に複合材のマトリクスとなる未硬化樹脂を充填し保持した樹脂充填体とを複合材料成形用の型内に設置し、温度を上げることによって保持体に充填した未硬化樹脂を溶融させた後、溶融した樹脂を複合材料の強化繊維又は繊維織物に含浸させることによって複合材料を成形しているので、従来は脆く強度の弱くフィルム化が不可能である未硬化樹脂に対しても、所定の位置に未硬化樹脂を保持することができ、強化繊維や繊維織物のようなプリフォームに対して所定の分布で溶融樹脂を含浸させることができるので、ＲＦＩ法による複合材料を簡単に製造することができる。
【図面の簡単な説明】
【図１】本発明による樹脂充填体の一例（実施例１〜８）を示す模式図である。
【図２】本発明による樹脂充填体の別の例（実施例９）を示す模式図である。
【図３】本発明における実施例１０〜１２において複合材平板をＲＦＩ法によって成形する際の模式図である。
【図４】本発明における強化繊維複合材の製造方法における圧力と温度とで定められる成形プログラムを示した図である。
【図５】本発明における強化繊維複合材料の製造方法による補強平板（実施例１４）を製作する際の模式図である。
【図６】本発明による樹脂充填用の開気孔部を有する樹脂充填体の顕微鏡写真である。
【符号の説明】
１，１０　樹脂充填体　　　　　　　　　　２，１１　保持体
３　ポリイミドフィルム（孔穿き）　　　　４　ポリイミドフィルム
５　樹脂フィルムの融着部　　　　　　　　６，１３　溶着部
７　孔　　　　　　　　　　　　　　　　　１２　区画
２０，３０　ＲＦＩ成形用の金型
２１，３１　金型の下型　　　　　　　　　　２２，３２　金型の上型
２３，３３　キャビティ　　　　　　　　　　２４，３４　ポンプ
２５，３５　プリフォーム（炭素繊維織物）
３６　突起部　　　　　　　　　　　　　　　３７　穴部[0001]
[Industrial applications]
The present invention relates to a resin-filled body used in the production of a fiber-reinforced composite material by a resin film infusion method (RFI method), and a method for producing a fiber-reinforced composite material using the resin-filled body.
[0002]
[Prior art]
Conventionally, materials for aerospace are required to have high strength and light weight. As a material used for these applications, there is an advanced composite material using a heat-curable resin as a matrix. As a method of manufacturing an advanced composite material, a prepreg in which fibers or a fiber woven fabric is pre-impregnated with an uncured resin serving as a matrix is manufactured, and the prepreg is laminated on a molding die or inside a die. The prepreg molding method of heating and pressurizing is the most common. An autoclave is generally used for the heating / pressing step of the prepreg, but a hot press or the like is used for a simple shape.
[0003]
On the other hand, as another method for producing an advanced composite material, a preform of fiber or fiber woven fabric is installed in a closed mold, and an uncured resin serving as a matrix is pressed into the preform in the mold from outside to form a preform. There is an RTM method (resin transfer molding method) in which the resin is cured by heating and pressing after impregnating the resin. The RTM method is characterized in that a product with good dimensional accuracy and finish roughness can be manufactured at low cost, and its application has been recently expanded, especially for aerospace applications.
[0004]
As a method similar to the RTM method, a preform made of fibers and woven fabric and an uncured resin film serving as a matrix are placed in a closed mold, and the resin is melted by heating the entirety. There is an RFI method (resin film infusion method) in which a resin is impregnated into a preform by depressurization and external pressure, and is further heated and cured. Unlike the RTM method, the RFI method does not require equipment for feeding and injecting resin from the outside, and a preform made of fibers and a woven fabric and an uncured resin film serving as a matrix are stacked and arranged in a mold. The feature is that the amount of resin impregnated in the preform per unit area can be accurately controlled by the film thickness, and a component having high dimensional accuracy and good flatness can be manufactured similarly to the RTM method. .
[0005]
However, an important technical problem in the RFI method is to make an uncured resin into a film. In the RFI method, an uncured resin film is required which has flexibility and strength so that the resin is uncured, but is not damaged by handling when manufacturing a composite material or pressure applied during molding. . However, it is known that it is not easy to produce a film applicable to the RFI method even with the most common epoxy resin because the resin in an uncured state generally has low strength and is brittle. In particular, in the case of a resin such as a thermosetting polyimide having a low molecular weight in an oligomer state and a glass transition temperature much higher than room temperature, it is practically impossible to produce a film from an uncured resin. It was impossible to apply.
[0006]
[Non-patent document 1]
B. Qi et al., "Resin Film Infusion (RFI) Process for Manufacturing Advanced Composite Structures", Composite Structures, Elsevier Science Ltd., 1999, No. 47. Vol., P. 471-476
[0007]
[Problems to be solved by the invention]
Therefore, the strength and low brittleness of the uncured resin, which is easily damaged by the pressure applied during molding and handling during the production of the composite material even if it is formed into a film, is maintained substantially in the predetermined shape and distribution of the uncured resin. However, there is a problem to be solved in that a structure capable of substantially maintaining a predetermined distribution with respect to a preform made of a reinforcing fiber or a fiber fabric can be used to manufacture a composite material.
[0008]
An object of the present invention is to provide a resin filler capable of being subjected to RFI molding for an uncured resin, which is difficult to be formed into a film for RFI molding, with respect to the above-mentioned prior art, and obtained by the method. To provide a method for producing a reinforcing fiber composite material using a resin filler for RFI molding.
[0009]
[Means for Solving the Problems]
In order to solve the above-described problems, a resin filler for producing a fiber-reinforced composite material according to the present invention is formed by filling an uncured resin which becomes a matrix of a composite material when impregnated with a reinforcing fiber or a fiber woven fabric into a holding body. The holder is configured so that the uncured resin melted by the temperature rise can flow out.
[0010]
According to the resin filler for producing a fiber-reinforced composite material, the uncured resin is filled and held in a thermally stable holder, and the holder bears mechanical strength and flexibility. Therefore, it does not depend on the strength of the uncured resin serving as the matrix of the composite material. Since the cured resin is filled and held in the holding body, even when the cured resin is brittle and its strength is low, the relative position with respect to the preform made of the reinforcing fiber or the fiber fabric may be largely shifted from a predetermined position. In addition, the preform can be impregnated with the uncured resin melted by the temperature rise by a predetermined amount in a predetermined distribution. Optimum materials for these holders include fluorinated ethylene resin and polyimide resin, but no specific material is specified.
[0011]
In this resin-filled body for producing a fiber-reinforced composite material, the holding body is made of the resin film that can be filled with the uncured resin, and at least a peripheral portion of the resin film is bonded or fused. Can be. Since the resin film can have the required mechanical strength and flexibility, when the uncured resin is formed into a thin film or film, it is accommodated by sandwiching such uncured resin between Can be maintained. By bonding or fusing at least the peripheral portion of the resin film, for example, a bag-shaped or shallow tray-shaped container can be formed, and even a low-strength uncured resin can be sufficiently held and communicated with the outside. Can be controlled. The resin film may be, for example, an arrangement in which one film is folded or two films are overlapped, and the inside is formed as an accommodating portion capable of accommodating an uncured resin by bonding or fusing the peripheral portion.
[0012]
In this resin-filled body for producing a fiber-reinforced composite material, the holder is divided into a plurality of sections, and the resin films can be bonded or fused to each other at a partition between adjacent sections. When the size of the resin filler increases, it may be difficult to maintain the shape as the resin filler. In such a case, the resin filler is divided into a plurality of sections having a size capable of maintaining the shape, the uncured resin is accommodated in each section, and the resin films between the sections are bonded or fused. Thereby, the strength and flexibility of the resin filler can be improved in response to an increase in size. The size of the section varies depending on the purpose of use, the thickness of the film, the type of the resin, and the like, but details are not specified.
[0013]
In a resin filler for manufacturing a fiber-reinforced composite material in which a holding body is formed from a resin film, at least one hole is formed in at least one of the resin films so that the molten uncured resin flows out. Can be. The resin film filled with the uncured resin needs a path for flowing out the resin melted by heating. For this purpose, for example, when the holding body is formed from two resin films, at least one of the resin films may be provided with at least one hole through which the molten resin passes. These holes can be drilled in advance in the resin film, or can be drilled immediately before installation in the mold. The present invention does not specify a specific perforation method for a resin outflow path.
[0014]
In a resin-filled body for producing a fiber-reinforced composite material in which a holding body is formed from a resin film, the peripheral portion or the partition portion has an unbonded or unfused part that can be partially connected to the outside or the adjacent section. State. At the end of the resin-filled body where the resin film is fused or bonded, a part of the resin-filled film is left unbonded or unfused from the beginning of the production of the resin-filled film, so that the unbonded or unfused part is formed. Can be used as a path for causing the resin melted by heating to flow out.
[0015]
In the resin-filled body for manufacturing a fiber-reinforced composite material in which the holding body is formed from a resin film, the peripheral portion or the partition portion is formed by bonding the resin film, and the strength of the bonding is the peripheral portion or the Part or all of the partition part can be set to have a strength that decreases in the melting temperature range of the resin. Another method of discharging the melted resin is to lower the bonding strength of a part or all of the bonding ends of the upper and lower two films filled with the resin in a temperature range where the filled resin is melted. Thus, it is also possible to allow the resin to flow out by intentionally peeling off the adhesive end of the film in a required temperature range.
[0016]
In this resin filler for producing a fiber-reinforced composite material, the uncured resin may be an uncured imide oligomer formed into a film by powder press molding or melt molding. Even for a polyimide that is difficult to mold, it can be heated and melted and impregnated into a preform by filling and holding it in a resin film.
[0017]
In the resin-filled body for producing a fiber-reinforced composite material, the holding body is a flexible porous body having a large number of open pores, and the uncured resin melts due to a rise in temperature. Is filled in the open pore portion so as to be able to flow out from the outside. A resin-filled body in which the open pores of the flexible porous body are filled with an uncured resin serving as a matrix of the composite material is placed in a composite material molding die together with the composite material reinforcing fiber or fiber woven fabric, and the temperature is reduced. When the resin filled in the open pores is melted by raising, the molten resin can be impregnated into the reinforcing fiber or the fiber fabric of the composite material for forming the composite material. The uncured resin is filled in the open pores of the thermally stable porous body, and since the mechanical strength and flexibility are provided by these porous bodies, they do not depend on the strength of the uncured resin. Since the porous body can be easily shaped, it is easy to manufacture a resin filler having a complicated shape, which is necessary when manufacturing a composite material having a complicated shape. For these holding films, a fluoroethylene resin, a polyimide resin, a silicone resin and the like are optimal, but specific materials are not specified.
[0018]
In the method for producing a fiber-reinforced composite material according to the present invention, a reinforcing fiber or a fiber woven fabric and the resin filler according to any one of claims 1 to 8 are installed in a composite material molding die, and the temperature is increased. In this way, the uncured resin filled in the resin-filled body is melted, and the molten uncured resin is impregnated into the reinforcing fibers or the fiber fabric.
[0019]
According to the method for producing a reinforcing fiber composite material, a reinforcing fiber or a fiber woven fabric of the composite material and a resin filler filled with an uncured resin serving as a matrix of the composite material are placed in a mold for forming a composite material. By raising the temperature, the uncured resin filled in the resin filler is melted, and the molten resin is impregnated into the reinforcing fibers of the composite material to form the composite material. In addition, at least a part of the resin film constituting the resin filler, in order to allow the molten uncured resin to flow out, at least one or more holes are pre-drilled or filled into a composite material molding die. It can be pierced just prior to dosing and placed in a composite molding die along with the reinforcing fibers or fiber fabric.
[0020]
【Example】
Hereinafter, embodiments of the present invention will be specifically described.
(Examples 1 to 9)
Examples of the present invention are shown in Table 1 and FIG. FIG. 1 is a schematic diagram illustrating an example of a resin filler. As shown in FIG. 1, the resin-filled body 1 shown in Examples 1 to 8 is composed of two polyimide films 3 and 4 (upilex manufactured by Ube Industries, Ltd.) as a resin film forming the holder 2 according to the present invention. (S, thickness 25 μm or 100 μm) in which an uncured imide oligomer film (hereinafter referred to as “uncured resin film”) 5 as an uncured resin according to the present invention is packed. The uncured resin film 5 is formed by molding a thermosetting polyimide (UPILEX AD, manufactured by Ube Industries, Ltd., average molecular weight MW: 1600 g / mole).
[Table 1]

[0021]
After the uncured resin film 5 is filled between the two polyimide films 3 and 4, the peripheral portions of the polyimide films 3 and 4 are fused with a fusion film to form a fused portion 6, so that the uncured resin film 5 is formed. The inside filled with the film 5 is sealed. Here, one polyimide film 3 is provided with holes 7 having a diameter of 1 mm (only some of them are denoted by reference numerals) at intervals of 4 mm. If the pore size is small, the flow of the molten resin when the uncured resin film 4 is melted is hindered. On the other hand, if the pore size is too large, cracks occur in the uncured resin film 5 and when the uncured resin film 5 is crushed finely, fragments of the uncured resin film 4 fall off. Needs careful consideration.
[0022]
The specific manufacturing procedure of the resin filler 1 is as follows. Examples 1 to 4 are examples in which an uncured resin film was molded by powder press molding as described in the column of uncured resin molding method in Table 1. First, the imide oligomer powder of Upilex AD obtained by the thermal imidization reaction of the polyamic acid was pulverized and classified to have an average particle size of about 30 μm or less. The powder thus obtained was formed into a 200 mm × 200 mm film using a press die. The uncured resin film 5 thus formed is vacuum-packed in the polyimide films 3 and 4 under reduced pressure, and the peripheral portions of the polyimide films 3 and 4 are fused using a polyimide fusion film to form a fused portion. 6, and the resin-filled body 1 was manufactured. As shown in Table 1, the thickness of the uncured resin film 5, which is the resin film portion excluding the polyimide films 3 and 4, is 0.94 mm, 1.88 mm, and 3.75 mm.
[0023]
On the other hand, Examples 5 to 8 are examples in which an uncured resin film was produced by melt molding of an imide oligomer, as described in the column of the uncured resin molding method in Table 1. After melting the imidized oligomer of Iupirex AD at 300 ° C. after completion of the thermal imidization, this was filled in a mold, and gradually cooled in the mold while slightly applying pressure, to obtain a 200 mm × 200 mm plate-like film. . The thus-obtained uncured resin film 5 is vacuum-packed into the polyimide films 3 and 4 under reduced pressure, and the polyimide films 3 and 4 are fused using the polyimide fusion film to form the resin-filled body 1. Made. As shown in Table 1, the thickness of the uncured resin film 5 excluding the polyimide films 3 and 4 is 0.68 mm, 1.36 mm, and 2.73 mm. In any case, since the film thickness was determined so that the areal density was the same from the areal density of the film necessary for manufacturing a composite material described later, Examples 1 to 4 molded by the powder pressing method were better. And thicker than Examples 5 to 8 formed by the melt molding method. Comparative Examples 1 and 2 are imide oligomers formed into films by powder press molding or melt molding, respectively.
[0024]
The appearance inspection results of the prototype resin filler 1 are shown in the rightmost column of Table 1. First, in Comparative Example 1, cracks occurred in the uncured resin film, and it was impossible to form a resin filler. Also, in Comparative Example 2, although an uncured resin film was barely formed, cracking occurred during handling, and it was found that application to an RFI molding film was completely unsuitable. On the other hand, in Examples according to the present invention, when the thickness was small, cracks and the like were not observed in the packed uncured resin film 5, and the resin filler 1 having good appearance was obtained. However, the thickness of the uncured resin film 5 increases in both the press-molded products of Examples 1 to 4 and the melt-molded products of Examples 5 to 8 (3.75 mm or 2.73 mm in the column of the film resin partial thickness). ) And a crack was observed in a part of the formed uncured resin film 5. The thicker polyimide films 3 and 4 holding the resin having a thickness of 100 μm (film specification for resin holding film) tended to be able to suppress cracking of the uncured resin film 5. Flexibility decreased. However, in the embodiment according to the present invention, even if a crack occurs in the filled uncured resin film 5, the shape retention as the resin filler 1 in which the crack is packed in the polyimide films 3 and 4 is not improved. There was no problem at all, and it was found that it had a shape retention property that was sufficiently applicable to RFI molding.
[0025]
Example 9 in Table 1 is an example in which the shape retention of the uncured resin film 5 is improved. FIG. 2 is a schematic diagram illustrating an example of a resin filler according to Example 9. As shown in FIG. 2, the resin-filled body 10 according to the ninth embodiment divides the uncured resin film 5 manufactured by melt molding into sections 12 each having a size of 200 × 200 mm, and forms a polyimide film constituting the holder 11. The sections 3 and 4 are fused between the sections 12 by the fusion section 13 similar to the fusion section 6, so that the overall size is 800 mm × 800 mm. As described above, when the size of the resin filler 10 is increased, the shape is maintained by dividing the uncured resin film 5 into a plurality of sections 12 having a size capable of retaining the shape as the resin filler. By improving the performance, it is possible to cope with an increase in size.
[0026]
Example 10 in Table 1 shows that when the uncured resin film 5 composed of the imide oligomer obtained by melt molding is packed between the polyimide films 3 and 4, the ends of the upper and lower two polyimide films 3 and 4 are removed. 3 shows a resin filler bonded using an epoxy resin-based adhesive instead of fusion. Since the strength of the used adhesive rapidly decreases when the temperature exceeds 200 ° C., the adhesive force of the bonding ends of the polyimide films 3 and 4 is rapidly reduced at a temperature at which the uncured resin film 5 melts (about 290 ° C. or higher), The molten uncured resin can be easily flowed out (or sucked out) from the end where the sealing force is reduced. In this method, there is an advantage that it is not necessary to make holes 7 as shown in FIG.
[0027]
(Examples 11 to 13)
Examples 11 to 13 shown in Table 2 are examples in which composite material flat plates were manufactured by the RFI method using the RFI molding resin filler 1 obtained according to the present invention. The reinforcing material used was a 5-sheet satin woven fabric having a high-strength carbon fiber T800HB-6K manufactured by Toray Industries, Inc. (the fabric weight is 312 g / m2). ² ). FIG. 3 is a schematic diagram showing a manufacturing process when the composite flat plate is subjected to RFI molding. First, a predetermined number (8 or 16) of carbon fiber fabrics cut into 160 × 160 mm were laminated in the lower mold 21 of the mold 20 to obtain a dry preform 25. On top of this, the resin-filled body 1 according to the present invention shown in Example 1 was placed so that the polyimide film 3 in which the holes 7 were formed was on the lower side. The target thickness per woven fabric was set to 0.3 mm, and the target plate thickness (2.4 mm or 4.8 mm) corresponding to the number of layers was set. In these examples, the calculated fiber volume fraction is about 58%.
[Table 2]

[0028]
FIG. 4 is a graphed molding program of the composite material in Examples 11 to 13. During the molding process, the pressure inside the mold 20 is constantly reduced by using the rotary pump 24. Iupirex AD (molecular weight 1600 version), which is an uncured resin, starts melting at about 280 ° C and drops at 300 ° C to a viscosity (10 Pa · s) sufficient for impregnation into a carbon fiber fabric. Then, after the temperature reaches 300 ° C., the pressurization of the mold 20 (pressurization of the upper mold 22) is started gradually, and the preform 25 is pressed in the cavity 23 formed between the lower mold 21 and the upper mold 22. Was impregnated with a polyimide resin. With the maximum clamping pressure of 10 ton applied, the temperature was further raised to 370 ° C. and held for one hour to cure the polyimide resin (uncured resin) to form a composite material. In all of Examples 11 to 13, the impregnation of the polyimide resin was good, and no defect was detected by ultrasonic testing. In addition, a non-porous compression test piece was cut out from the produced composite flat plate, and the compression strength was measured. The result was also good.
[0029]
However, as in Example 12, when the thickness of the composite material is increased and the thickness of the resin filler 1 is increased, wrinkles are generated in the resin filler 1 after the polyimide resin flows out, and this is transferred to the surface of the composite material. Therefore, the smoothness of the surface is impaired. In the case where the plate thickness is large, the thickness of each resin filler 1 is reduced by disposing the resin fillers 1, 1 on the upper and lower sides of the preform 25 as in the thirteenth embodiment. It is effective to suppress wrinkles generated in the filling body 1.
[0030]
Example 14 is an example in which a flat plate having a reinforcing structure is integrally formed by RFI molding using the resin filling 1 for RFI molding according to the present invention. FIG. 5 is a schematic diagram illustrating an example of a method of manufacturing a flat plate having a reinforcing structure according to Example 14 by the method of manufacturing a reinforcing fiber composite material according to the present invention. In Example 14, since the resin filler 1 was relatively thick and small, a resin film of the type employing the sealing structure with the adhesive shown in Example 10 was used instead of the film having the holes 7 perforated. The mold 30 is, like the mold 20 shown in FIG. 3, a lower mold 31, an upper mold 32 that forms a cavity 33 together with the lower mold 31, and a rotary pump that sucks and exhausts air in the cavity 33 to create a negative pressure. 34. The upper die 32 has a hole 37 formed in conformity with the shape of the preform 35 having the reinforcing projections 36. The forming program of the composite material having the reinforcing structure is the same as the program shown in FIG. The formed reinforcing plate did not show any particular defect as a result of the ultrasonic inspection, and good results were obtained. As described above, by using the resin-filled body 1 of the present invention, it is possible to easily manufacture a composite material product having a complicated shape.
[0031]
(Example 15)
Example 15 is an example of a resin-filled body in which a resin serving as a matrix of a composite material is filled into open pores of a flexible porous body constituting a holding body. As the porous body, porous polyimide (UPILEX Foam BF301 manufactured by Ube Industries, Ltd., density 0.01 g / cm) ³ )It was used. The specific manufacturing procedure is as follows. First, Iupirex AD (molecular weight: about 1600) was heated and melted at 300 ° C., and was filled into the open pores of a 3 mm thick Iupirex foam by a vacuum impregnation method. Although Iupirex foam is a foam material, the wall thickness is thin, so most of the Iupirex foam has open pores open to the outside, and the resin is filled well. The obtained resin-filled body is inferior in flexibility, unlike the resin-filled body 1 shown in Examples 1 to 10, but hardly falls off the impregnated uncured resin, and is sufficient as a resin-filled body for RFI molding. Could be used. Since the porous body is easy to shape, there is an advantage that a complicated-shaped resin filler required for manufacturing a complex-shaped composite material can be easily manufactured. In the micrograph shown in FIG. 6, the surface of the resin-filled body in which the open pores filled with the resin serving as the matrix of the composite material are formed is photographed.
[0032]
【The invention's effect】
As described above, according to the resin filler for producing a fiber-reinforced composite material of the present invention, the uncured resin serving as a matrix of the composite material when impregnated into the reinforcing fibers or the fiber woven fabric is filled in the holding body. Since the holding member is configured to allow the uncured resin melted by the temperature rise to flow to the outside, a predetermined strength is required even for an uncured resin which is conventionally brittle and has a weak strength and cannot be formed into a film. The uncured resin can be held at the position, and handling becomes very easy without concern for the uncured resin being crushed or broken. Also, the position and distribution of the uncured resin with respect to the preform can be maintained at predetermined positions and distributions. When the size of the resin filler increases, the resin filler is divided into several sections, and the two films between the sections are bonded or fused to each other to obtain the strength of the resin filler. And flexibility can be improved. Furthermore, by filling the open pores of the flexible porous body with a resin that serves as a matrix of the composite material, it is possible to form a resin having a complicated shape even with a resin that cannot be formed into a film of an uncured resin. The production of a composite material by the RFI method can also be provided for a reform.
[0033]
Further, according to the method for producing a fiber-reinforced composite material according to the present invention, a reinforcing material or a fiber woven fabric of the composite material, and a resin-filled body in which an uncured resin serving as a matrix of the composite material is filled and held in a holding body After placing in a mold for molding and melting the uncured resin filled in the holder by raising the temperature, the molten resin is impregnated into the reinforcing fiber or fiber woven fabric of the composite material to form the composite material. As a result, it is possible to hold the uncured resin in a predetermined position even for an uncured resin that is conventionally brittle and weak in strength and cannot be formed into a film, and it can be used for preforms such as reinforcing fibers and fiber fabrics. On the other hand, since the molten resin can be impregnated with a predetermined distribution, a composite material by the RFI method can be easily manufactured.
[Brief description of the drawings]
FIG. 1 is a schematic view showing one example (Examples 1 to 8) of a resin filler according to the present invention.
FIG. 2 is a schematic view showing another example (Example 9) of a resin filler according to the present invention.
FIG. 3 is a schematic diagram when a composite flat plate is formed by the RFI method in Examples 10 to 12 of the present invention.
FIG. 4 is a diagram showing a molding program defined by pressure and temperature in the method for producing a reinforcing fiber composite material according to the present invention.
FIG. 5 is a schematic diagram when a reinforcing flat plate (Example 14) is manufactured by the method of manufacturing a reinforcing fiber composite material according to the present invention.
FIG. 6 is a micrograph of a resin-filled body having open pores for resin-filling according to the present invention.
[Explanation of symbols]
1,10 Resin filled body 2,11 Holder
3 Polyimide film (perforated) 4 Polyimide film
5 Welding part of resin film 6, 13 Welding part
7 holes 12 sections
20,30 Mold for RFI molding
21,31 Lower mold 22,32 Upper mold
23,33 cavity 24,34 pump
25,35 preform (carbon fiber fabric)
36 Projection 37 Hole

Claims (9)

An uncured resin that becomes a matrix of a composite material when impregnated into a reinforcing fiber or a fiber woven fabric is filled in a holding body, and the holding body can flow out the uncured resin melted by a rise in temperature to the outside. A resin-filled body for producing a fiber-reinforced composite material, comprising: 2. The fiber-reinforced composite material according to claim 1, wherein the holder is made of a resin film in which the uncured resin can be filled, and at least a peripheral portion of the resin film is adhered or fused. 3. Resin filler for manufacturing. 3. The fiber-reinforced composite material according to claim 2, wherein the holder is divided into a plurality of sections, and the resin films are bonded or fused to each other at a partition between the adjacent sections. Resin filling. The resin for producing a fiber-reinforced composite material according to claim 2, wherein at least a part of the resin film has at least one or more holes through which the molten uncured resin flows out. 5. Filled body. The fiber according to any one of claims 2 to 4, wherein the peripheral portion or the partition portion is in an unbonded or unfused state in which a part thereof can communicate with the outside or the adjacent section. Resin filler for reinforced composite material production. The peripheral portion or the partition portion is formed by bonding the resin film, and the strength of the bonding is such that the peripheral portion or the partition portion is partially or wholly reduced in a melting temperature range of the resin. The resin filler for producing a fiber-reinforced composite material according to claim 2, which is set. 2. The resin filler according to claim 1, wherein the uncured resin is an uncured imide oligomer formed into a film by powder press molding or melt molding. 3. The holding body is a flexible porous body having a large number of open pores, and the uncured resin is filled into the open pores so as to be able to flow out of the open pores when melted due to a rise in temperature. A resin filler for producing a fiber-reinforced composite material according to claim 1, comprising: The reinforcing fiber or fiber woven fabric, and the resin-filled body according to any one of claims 1 to 8 is installed in a mold for forming a composite material, and the resin-filled body is filled by raising the temperature. A method for producing a fiber-reinforced composite material, comprising melting an uncured resin and impregnating the molten uncured resin into the reinforcing fibers or the fiber fabric.

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