JP6160095B2 - Carbon fiber reinforced thermoplastic resin prepreg sheet or molded product - Google Patents
Carbon fiber reinforced thermoplastic resin prepreg sheet or molded product Download PDFInfo
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本発明は、炭素繊維強化熱可塑性樹脂からなるプリプレグシートまたは成形品に関する。詳しくは、強度や弾性率がたいへん高く、かつ成形品面内の各方向の線膨張係数が等方的で、かつその絶対値が非常に小さいことから、寸法精度が高く、かつ温度変化に対して寸法安定性の高いプリプレグシートまたは成形品に関する。 The present invention relates to a prepreg sheet or molded article made of a carbon fiber reinforced thermoplastic resin. Specifically, the strength and elastic modulus are very high, the linear expansion coefficient in each direction in the molded product surface is isotropic, and its absolute value is very small. It relates to a prepreg sheet or molded product having high dimensional stability.
近年、構造材用として開発された長繊維強化熱可塑性樹脂（例えば、非特許文献１参照）は、高い強度や剛性を有することから板状や梁状構造材として使用されるようになった。構造材として使用する場合、高い強度や剛性が要求されるばかりではなく、温度や湿度のような環境変化に対して、寸法精度が高いことが必要である。特に、板状で使用する成形品においては、どの方向に対しても、寸法変化が小さく、かつ方向による寸法変化の異方性が小さいことが要求される。長繊維強化熱可塑性樹脂は、繊維の軸方向の線膨張係数は大変小さいが、繊維の長さ軸に直交する方向に対しては、繊維の線膨張係数を抑える効果は活かされず、樹脂単体の線膨張係数よりむしろ線膨張係数は高くなるのが一般的である。結果として、繊維の長さ軸方向とその直交方向では、線膨張係数の差は大変大きくなり、大きな異方性を示す。線膨張係数の異方性による寸法差は、成形品の寸法の大きなバラツキや成形品のソリやねじれの原因となる。また繊維軸に対して直角方向の引っ張り変形に対しては、繊維の補強効果が活かされないので、繊維の軸方向に対して直角方向の強度や剛性は低く、従って、成形品の機械的性質の異方性が大変大きく、実用に当っては、構造材としての信頼性改善も課題であった。 In recent years, long fiber reinforced thermoplastic resins developed for structural materials (see, for example, Non-Patent Document 1) have been used as plate-like or beam-like structural materials because of their high strength and rigidity. When used as a structural material, not only high strength and rigidity are required, but also high dimensional accuracy is required against environmental changes such as temperature and humidity. In particular, a molded product used in a plate shape is required to have a small dimensional change in any direction and a small anisotropy of the dimensional change depending on the direction. The long fiber reinforced thermoplastic resin has a very small linear expansion coefficient in the axial direction of the fiber, but the effect of suppressing the linear expansion coefficient of the fiber is not utilized in the direction orthogonal to the longitudinal axis of the fiber. It is common for the linear expansion coefficient to be higher than the linear expansion coefficient. As a result, the difference in linear expansion coefficient between the longitudinal direction of the fiber and the direction orthogonal thereto is very large and exhibits great anisotropy. The dimensional difference due to the anisotropy of the linear expansion coefficient causes a large variation in the dimensions of the molded product, and warping or twisting of the molded product. Also, the tensile effect in the direction perpendicular to the fiber axis does not utilize the reinforcing effect of the fiber, so the strength and rigidity in the direction perpendicular to the fiber axis direction are low, and therefore the mechanical properties of the molded product. Anisotropy is very large, and improvement of reliability as a structural material has been an issue in practical use.
これまで、特開２００４−２３１６９７号公報（特許文献１）や特開２００６−２９１０７６号公報（特許文献２）に、線膨張係数の異方性が１．０〜２．５の材料が開示されている。しかし、線膨張係数の絶対値は低く限定されておらず、また線膨張係数の異方性も１．０近傍に限定されておらず、開示された材料は精密部品向けの高度な寸法精度や寸法安定性の要求にはマッチングしなかった。また特開平６−９８８８号公報（特許文献３）に、平均長０．０５〜１３ｍｍのガラス繊維と平均長０．０５ｍｍ〜１５ｍｍの炭素繊維と平均長５〜１２０μｍのチタン酸カリウムを配合した精密成形用組成物が開示されている。しかし、この組成物は、やはり本発明の狙いとは、線膨張係数の異方性や絶対値の要求値において大きな乖離が有り、目的に合わなかった。また特開２００９−１４９８２３号公報（特許文献４）に、ポリプロピレン系樹脂に炭素繊維０．５〜２０重量％を配合した組成物が開示されている。しかしやはり強度と寸法精度や寸法安定性のレベルにおいて本発明の狙いとは大きな乖離があり、精密部材に使用されるものでなかった。 So far, Japanese Patent Application Laid-Open No. 2004-231697 (Patent Document 1) and Japanese Patent Application Laid-Open No. 2006-291076 (Patent Document 2) have disclosed materials having anisotropy of linear expansion coefficient of 1.0 to 2.5. ing. However, the absolute value of the linear expansion coefficient is not limited to a low value, and the anisotropy of the linear expansion coefficient is not limited to around 1.0, and the disclosed material has high dimensional accuracy for precision parts and It did not match the requirements for dimensional stability. Moreover, the precision which mix | blended Unexamined-Japanese-Patent No. 6-9888 (patent document 3) the glass fiber of average length 0.05-13mm, the carbon fiber of average length 0.05mm-15mm, and potassium titanate of average length 5-120micrometer. A molding composition is disclosed. However, this composition did not meet the purpose of the present invention, because there was a great difference in the anisotropy of the linear expansion coefficient and the required value of the absolute value. Japanese Unexamined Patent Application Publication No. 2009-149823 (Patent Document 4) discloses a composition in which 0.5 to 20% by weight of carbon fiber is blended with a polypropylene resin. However, there is still a great difference from the aim of the present invention in the level of strength, dimensional accuracy and dimensional stability, and it was not used for precision members.
また特開２０１０−１８７２４号公報（特許文献５）のように、強化繊維として、異方性の小さい不織布状の強化繊維を使用し、強化繊維に切り込みを入れて金型を転写する程度の距離を流動することや、特開２００７−２６２３６０号公報（特許文献６）のように、ランダムに配置したチョップドストランドマットに樹脂を含浸してプリプレグシートを作製することが開示された。複合化効果を得るためには高い含浸性が必要であるが、繊維含有率が高くなると含浸が困難となるため、高い繊維含有率の成形品が得られず、本発明の狙いとする高強度の成形品は得られなかった。また得られた複合材の繊維補強効果が小さいため、樹脂の大きな熱膨張を抑制するには不十分であり、また強度や弾性率も構造材としての要求にかなり未達であった。また等方性の複合材を得るために、流動抵抗により繊維が配向しにくいように繊維の長さを短くすることも開示されたが、繊維が短いと補強効果が得られず物性が要求に未達であった。また特開２００５−３２４３４０号公報（特許文献７）のように、流動する不連続繊維強化層と殆ど流動しない連続繊維強化層を組み合わせることが開示された。しかし、連続繊維層は、繊維軸に対して垂直方向には流動しないことから、成形品に欠肉が発生するか、流れ込んだ不連続繊維強化層では強度的に要求に満たない欠陥が発生しやすく、特別な成形品以外の場合品質上問題があり、一般的では無かった。 Further, as disclosed in JP 2010-18724 A (Patent Document 5), a nonwoven fabric-like reinforcing fiber having a small anisotropy is used as the reinforcing fiber, and the distance is such that the reinforcing fiber is cut and the mold is transferred. It is disclosed that a prepreg sheet is produced by impregnating a resin into a randomly arranged chopped strand mat as disclosed in Japanese Patent Application Laid-Open No. 2007-262360 (Patent Document 6). In order to obtain a composite effect, high impregnation is necessary, but impregnation becomes difficult when the fiber content becomes high, so a molded product with high fiber content cannot be obtained, and the high strength targeted by the present invention No molded product was obtained. Further, since the fiber reinforcing effect of the obtained composite material is small, it is insufficient to suppress the large thermal expansion of the resin, and the strength and the elastic modulus are not sufficiently met with the requirements as a structural material. In addition, in order to obtain an isotropic composite material, it has been disclosed that the length of the fiber is shortened so that the fiber is not easily oriented by flow resistance, but if the fiber is short, a reinforcing effect cannot be obtained and physical properties are required. It was not achieved. Further, as disclosed in JP-A-2005-324340 (Patent Document 7), it has been disclosed to combine a discontinuous fiber reinforced layer that flows and a continuous fiber reinforced layer that hardly flows. However, since the continuous fiber layer does not flow in the direction perpendicular to the fiber axis, the molded product may be thinned, or the discontinuous fiber reinforced layer that has flowed in may have defects that do not meet the requirements in terms of strength. It was easy and there was a problem in quality in cases other than special molded products, and it was not common.
国際公開ＷＯ２００７／２０９１０号公報（特許文献８）のように、長繊維を長さ方向に配向して、含浸して得られたテープを短冊状に切断し、ランダムに積層して、異方性の小さいシート状予備成形体を作製する方法が提案された。再成形前は、繊維配向は擬似ランダム状態に散布しているから、プリプレグと再成形品の面積比を小さくすることで異方性の小さい成形品が得られるようになった。しかし、使用環境温度変化に対して、線膨張係数に相当する寸法変化を示すことから、寸法変化や界面で内部応力が発現しやすく、使用環境が大きく変化する用途の精密部品において、局所的な寸法変化差による寸法精度や形状精度が問題となり、適用できない場合が多々あった。また特開２０１１−１８９７４７号公報（特許文献９）に、長さ分布の異なる強化繊維を組み合わせることで、線膨張係数のような物性を等方化することが開示されている。短い繊維が、流動で配向しにくい効果を狙ったものである。しかし、射出成形用の短繊維強化熱可塑性樹脂で当業界ではよく知られているように、繊維の補強効果が得られる長さ／繊維径が１００以上となる強化繊維からなるプリプレグを流動させた場合、やはり流動抵抗の影響を受け易く、繊維は配向し、また繊維の長さは短くても流動による配向の乱れ効果はたいへん小さく、１．３倍超えて流動させた場合、その効果は全く不十分であった。また、特開２０１１−１１３６２号公報（特許文献１０）に開示されたように、複数の一方向性に配向した繊維を配置して、例えば直交に配列して擬似等方性を保持することが開示されている。しかし、この場合、繊維の軸方向に繊維強化された樹脂は殆ど流動しなく、金型の転写性が悪く、投影面積の広い成形品には適用し難かった。
一方、長繊維強化の熱可塑性複合材料は、単位重量当りの強度や剛性が高いことから、自動車軽量化のために使用したい市場の根強い希望があり、等方的で高い流動性を有し、容量の小さい成形機で成形が可能であり、かつ使用環境変化が大きい場合においても、寸法変化や内部応力の小さい構造材やそれが得られる成形方法の強い開発要請があった。
As in International Publication No. WO2007 / 20910 (Patent Document 8), tapes obtained by orienting long fibers in the length direction and impregnated are cut into strips, laminated randomly, and anisotropic. A method for producing a small sheet-shaped preform was proposed. Prior to re-molding, the fiber orientation was dispersed in a pseudo-random state, so that a molded product with low anisotropy can be obtained by reducing the area ratio between the prepreg and the re-molded product. However, because it shows a dimensional change corresponding to the linear expansion coefficient with respect to changes in the operating environment temperature, internal stress is likely to appear at the dimensional change and interface, and in precision parts for applications where the operating environment changes greatly, There are many cases where dimensional accuracy and shape accuracy due to dimensional change differences are problematic and cannot be applied. Japanese Unexamined Patent Application Publication No. 2011-189747 (Patent Document 9) discloses that physical properties such as a linear expansion coefficient are made isotropic by combining reinforcing fibers having different length distributions. A short fiber aims at the effect that it is hard to orient by flow. However, as is well known in the art for short fiber reinforced thermoplastic resins for injection molding, a prepreg made of reinforcing fibers having a length / fiber diameter of 100 or more that can provide a fiber reinforcing effect was flowed. In this case, it is still susceptible to flow resistance, the fibers are oriented, and even if the length of the fibers is short, the effect of disturbance of orientation due to flow is very small. It was insufficient. Further, as disclosed in Japanese Patent Application Laid-Open No. 2011-11362 (Patent Document 10), it is possible to arrange a plurality of unidirectionally oriented fibers and arrange them orthogonally, for example, to maintain pseudo-isotropicity. It is disclosed. However, in this case, the resin reinforced with fiber in the axial direction of the fiber hardly flows, the transferability of the mold is poor, and it is difficult to apply to a molded product having a large projected area.
On the other hand, thermoplastic composites reinforced with long fibers have high strength and rigidity per unit weight, so there is a strong desire in the market to use for automobile weight reduction, isotropic and high fluidity, Even when molding is possible with a molding machine having a small capacity, and there is a great change in usage environment, there has been a strong demand for development of a structural material with small dimensional change and internal stress and a molding method for obtaining the structural material.
本発明の狙いは、寸法安定性が必要な板状や梁状構造材として使用される、高い強度や剛性を有し、温度のような環境変化に対して、寸法変化が小さく、かつ方向による寸法変化の異方性が小さい寸法精度が高い複合材を提供することである。 The aim of the present invention is to be used as a plate-like or beam-like structural material that requires dimensional stability, has high strength and rigidity, has little dimensional change with respect to environmental changes such as temperature, and depends on the direction. It is to provide a composite material with small dimensional change anisotropy and high dimensional accuracy.
本発明者らは、長繊維強化熱可塑性樹脂複合材において、変形方向や場所によらず高い強度や剛性が高く、さらに寸法精度と寸法安定性が高い成形品を得るべき鋭意検討した結果、以下に示す手段により、上記課題を解決できることを見出し、本発明に到達した。
すなわち、本発明は、以下の構成からなる。
１．熱可塑性樹脂２５〜５０質量％と長さ７．５ｍｍ〜１００ｍｍの炭素繊維５０〜７５質量％を含有するプリプレグシートまたは成形品であって、そのプリプレグシートまたは成形品の面内の任意の直交する２方向の線膨張係数が、共に−０．５×１０−５〜０．５×１０−５ｃｍ／ｃｍ／Ｋの範囲であることを特徴とする炭素繊維強化熱可塑性樹脂プリプレグシートまたは成形品。
２．プリプレグシートまたは成形品の厚さ方向断面（１ｍｍ×１ｍｍ）内において、炭素繊維の断面における長軸ｍに対する短軸ｎの比で表される楕円度ｎ／ｍが（１）式、（２）式、及び（３）式をそれぞれ満たす異方向に配向した単繊維を、それぞれ１００本以上含む繊維束領域を含有することを特徴とする前記１．に記載の炭素繊維強化熱可塑性樹脂プリプレグシートまたは成形品。
０．８≦ｎ／ｍ≦１．０ （１）
０．４≦ｎ／ｍ≦０．６ （２）
０．０１≦ｎ／ｍ≦０．２ （３）
３．熱可塑性樹脂がポリオレフィン樹脂、ポリアミド樹脂、ポリフェニレンスルフィド樹脂から選ばれた１種以上の樹脂からなることを特徴とする前記１．又は２．記載の繊維強化熱可塑性樹脂プリプレグシートまたは成形品が好ましい態様である。
As a result of intensive studies to obtain a molded product having high strength and rigidity, high dimensional accuracy and dimensional stability, regardless of the deformation direction and location, the present inventors have obtained the following results in the long fiber reinforced thermoplastic resin composite material. It has been found that the above-mentioned problems can be solved by the means shown in the above, and the present invention has been achieved.
That is, this invention consists of the following structures.
1. A prepreg sheet or molded product containing 25 to 50% by mass of a thermoplastic resin and 50 to 75% by mass of carbon fibers having a length of 7.5 to 100 mm, and is orthogonal to each other in the plane of the prepreg sheet or molded product Carbon fiber reinforced thermoplastic resin prepreg sheet or molded product characterized in that linear expansion coefficients in both directions are in the range of −0.5 × 10 −5 to 0.5 × 10 −5 cm / cm / K. .
2. In the cross section (1 mm × 1 mm) in the thickness direction of the prepreg sheet or molded product, the ellipticity n / m represented by the ratio of the short axis n to the long axis m in the cross section of the carbon fiber is the formula (1), (2) 1. A fiber bundle region containing 100 or more single fibers oriented in different directions respectively satisfying the formula (1) and the formula (3). The carbon fiber reinforced thermoplastic resin prepreg sheet or molded article described in 1.
0.8 ≦ n / m ≦ 1.0 (1)
0.4 ≦ n / m ≦ 0.6 (2)
0.01 ≦ n / m ≦ 0.2 (3)
3. The thermoplastic resin is composed of one or more resins selected from polyolefin resins, polyamide resins, and polyphenylene sulfide resins. Or 2. The described fiber-reinforced thermoplastic resin prepreg sheet or molded article is a preferred embodiment.
高い繊維補強効果と寸法安定性という相反する物性を両立する本発明の狙いが、なぜ達成されたかはまだ明確ではないが、（１）強化繊維として極小または負の線膨張係数を有する炭素繊維を使用したこと、（２）繊維含有率がたいへん高く、熱可塑性樹脂分率が大変低い状態で複合化できたこと、（３）炭素繊維の長さ軸が局所的に高度に配向し繊維束状態をとることにより、引張り方向と共に圧縮方向においても高い補強効果を有すること、（４）炭素繊維の長さ軸の分布が厚さ軸方向や面内の多軸方向で平均化し、擬似ランダム化できる条件がすべて満たされた効果によるもの考察される。 It is not yet clear why the aim of the present invention that achieves both the high fiber reinforcing effect and the contradictory physical properties of dimensional stability has been achieved, but (1) a carbon fiber having a minimal or negative linear expansion coefficient as a reinforcing fiber. (2) The fiber content was very high and the thermoplastic resin fraction was able to be composited in a very low state, (3) The carbon fiber length axis was locally highly oriented and the fiber bundle state (4) The distribution of the length axis of the carbon fiber can be averaged in the thickness axis direction or in the in-plane multiaxial direction, and can be pseudo-randomized. All the conditions will be considered due to the fulfilled effect.
本発明のプリプレグや成形品は、線膨張係数の絶対値が大変小さいことから、環境温度の変化による寸法変化が極めて小さく、寸法安定性がすぐれている。また線膨張係数の方向による差も小さいことから、環境温度変化による成形品の変形やソリの発生は極めて抑制されており、形状安定性に優れている。本発明により、環境温度変化に対して、寸法や形状が安定している成形品の提供が可能になり、寸法精度が高い構造材や精密工業部品が得られる。 Since the absolute value of the linear expansion coefficient of the prepreg or molded product of the present invention is very small, the dimensional change due to a change in environmental temperature is extremely small, and the dimensional stability is excellent. Further, since the difference depending on the direction of the linear expansion coefficient is small, the deformation of the molded product and the generation of warp due to the environmental temperature change are extremely suppressed, and the shape stability is excellent. According to the present invention, it is possible to provide a molded product having a stable dimension and shape against environmental temperature changes, and a structural material and a precision industrial part with high dimensional accuracy can be obtained.
成形品断面写真のモデル図である。繊維の長さ軸の配向により、炭素繊維断面の楕円度が異なる。断面における同じ楕円度を示す集合状態は、炭素繊維が繊維束をなして、長さ軸は配向していることを示している。 It is a model figure of a molded article sectional photograph. Depending on the orientation of the fiber length axis, the ellipticity of the carbon fiber cross section varies. The aggregated state showing the same ellipticity in the cross section indicates that the carbon fibers form a fiber bundle and the length axis is oriented.
以下、本発明を詳述する。
本発明のシートまたは成形品における線膨張係数とは、シートまたは成形品の平面・立面・側面の投影面積の中で、その面積が最大となる成形品の面に関し、その面の重心近傍で面積が１ｃｍ２以上で厚さが均一な部分について代表され、そこから採取された試験片について、２０℃と１２０℃間の線膨張係数の平均値を意味する。
本発明には炭素繊維が使用される。本発明に使用される炭素繊維は特に限定されないが、負の線膨張係数、さらに好ましくはその絶対値が１．０×１０−６ｃｍ／ｃｍ／Ｋ以下の線膨張係数を有する炭素繊維が好ましい。炭素繊維の線膨張係数が正であると、樹脂の線膨張係数と複合して寸法安定性が低下するから好ましくない。本発明に使用される炭素繊維は、その前駆体や製造法に特に制限されないが、ポリアクリロニトル繊維やセルロース繊維などの繊維を空気中で２００〜３００℃にて処理した後、不活性ガス中で１０００〜３０００℃以上で焼成され炭化製造された引っ張り強度２０ｔ／ｃｍ２以上、引っ張り弾性率２００ＧＰａ以上の炭素繊維が好ましい。本発明に使用される単繊維径は、特に制限されないが、複合化の製造ライン工程から３〜２０μｍが好ましく、特に４〜１５μｍ好ましい。３μｍ未満では、含浸や脱泡が難しく、２０μｍを超えると、比表面積が小さくなり、複合化の効果が小さくなり好ましくない。本発明に使用される炭素繊維は、空気や硝酸による湿式酸化、乾式酸化、ヒートクリーニング、ウイスカライジングなどによる接着性改良のための処理されたものが好ましい。また本発明の複合材料製造に使用される炭素繊維は、作業工程の取り扱い性から、１２０℃以下で軟化する収束剤により収束されていることが好ましい。収束フィラメント数には特に制限ないが、１０００〜３００００フィラメント、好ましくは、５０００〜２５０００フィラメントが好ましい。
The present invention is described in detail below.
The linear expansion coefficient in the sheet or molded product of the present invention refers to the surface of the molded product that has the maximum area among the projected areas of the plane, elevation, and side surfaces of the sheet or molded product, and is near the center of gravity of the surface. This is represented by a portion having an area of 1 cm 2 or more and a uniform thickness, and means the average value of the linear expansion coefficient between 20 ° C. and 120 ° C. for a test piece taken therefrom.
Carbon fiber is used in the present invention. The carbon fiber used in the present invention is not particularly limited, but a carbon fiber having a negative linear expansion coefficient, more preferably a linear expansion coefficient whose absolute value is 1.0 × 10 −6 cm / cm / K or less is preferable. . When the linear expansion coefficient of the carbon fiber is positive, it is not preferable because it is combined with the linear expansion coefficient of the resin and the dimensional stability is lowered. The carbon fiber used in the present invention is not particularly limited by its precursor and production method, but after treating fibers such as polyacrylonitrile fiber and cellulose fiber in air at 200 to 300 ° C., in an inert gas Carbon fibers having a tensile strength of 20 t / cm 2 or more and a tensile modulus of 200 GPa or more that are calcined and produced by carbonization at 1000 to 3000 ° C. are preferable. The diameter of the single fiber used in the present invention is not particularly limited, but is preferably 3 to 20 μm, particularly preferably 4 to 15 μm, from the production line step of the composite. If it is less than 3 μm, impregnation and defoaming are difficult, and if it exceeds 20 μm, the specific surface area becomes small, and the effect of compositing becomes small. The carbon fiber used in the present invention is preferably treated for improving adhesion by wet oxidation with air or nitric acid, dry oxidation, heat cleaning, whiskerizing, or the like. Moreover, it is preferable that the carbon fiber used for composite material manufacture of this invention is converged by the sizing agent which softens at 120 degrees C or less from the handleability of a work process. Although there is no restriction | limiting in particular in the number of converging filaments, 1000-30000 filaments, Preferably 5000-25000 filaments are preferable.
本発明は、長さ７．５ｍｍ〜１００ｍｍ、好ましくは２５ｍｍ〜７５ｍｍの炭素繊維を含有するプリプレグシート（予備成形体）または成形品である。炭素繊維の長さが７．５ｍｍ未満では、補強効果は小さく高い強度が得られず本発明の目的に適合しない。また１００ｍｍを超えると、金型内での流動抵抗が高く、成形上好ましくない。また本発明は、５０〜７５質量％、好ましくは、５５〜７０質量％の炭素繊維を含有したプリプレグシート（予備成形体）または成形品に関する。５０質量％未満では、構造材としての高い強度が得られず本発明の目的に適合しない。また７５質量％を超えると、樹脂流動に伴い、繊維間の絡み合いがおこりやすく成形性が低下して好ましくない。 The present invention is a prepreg sheet (preliminary molded article) or molded article containing carbon fibers having a length of 7.5 mm to 100 mm, preferably 25 mm to 75 mm. If the length of the carbon fiber is less than 7.5 mm, the reinforcing effect is small and a high strength cannot be obtained, which is not suitable for the purpose of the present invention. Moreover, when it exceeds 100 mm, the flow resistance in a metal mold | die is high and is unpreferable on a shaping | molding. The present invention also relates to a prepreg sheet (preliminary molded article) or molded article containing 50 to 75% by mass, preferably 55 to 70% by mass of carbon fiber. If it is less than 50% by mass, high strength as a structural material cannot be obtained, and this does not meet the object of the present invention. On the other hand, if it exceeds 75% by mass, entanglement between fibers tends to occur with resin flow, and the moldability is lowered, which is not preferable.
本発明において、圧縮成形して得られた成形品の厚さ方向１ｍｍ×１ｍｍ断面において、炭素繊維の断面において、ｍは繊維断面の長径、ｎは短径とした場合、その楕円度ｎ／ｍがそれぞれ０．８〜１．０からなる領域と、０．４〜０．６からなる領域と、０．０１〜０．２からなる領域があり、それぞれの領域で１００本以上、より好ましくは２００本以上、特に５００本以上が隣接する単繊維を含有する繊維束領域を持つことが好ましい態様である。領域は層と見ることもできる。断面の単繊維の楕円度は、単繊維軸の配向の尺度である。楕円度が１の場合は、単繊維は成形品断面に垂直に配向していることを意味する。また楕円度が小さい程、実質的には０．１未満では単繊維が成形品断面に平行に配向していることを意味する。０．１４の場合は、成形品断面に対して４５度の、０．５の場合、成形品断面に対して６０度に配向していることを意味する。隣接する単繊維の楕円度差が、平均楕円度の１０％以下である繊維の長さ軸が揃った単繊維束群が領域を形成していることが好ましい態様である。各領域に含まれる単繊維が１００本未満では、繊維束としての流動性や剛性を示さないから、本発明には好ましくない。また、成形品厚さ方向断面１ｍｍ×１ｍｍ内に、楕円度が大きく異なる繊維束領域があるということは、配向軸が異なる繊維束を含有し、複合効果により厚さ方向に線膨張係数を平均化することを意味している。
本発明の炭素繊維の断面の短径ｎは、４〜１０μｍ、好ましくは５〜９μｍであることが好ましい態様である。４μｍ未満では、単繊維の剛性が低く、繊維軸が湾曲しやすく好ましくない。また１０μｍを超えると繊維の強度が低く、本発明の効果が小さく、好ましい態様とならない。この理由はまだ明確ではないが、本発明は、繊維軸の方向が揃った隣接する繊維束の周囲を樹脂層で覆われていると達成されやすい。成形時の流動中に炭素繊維が絡み合いや切断することを抑制される効果と考察される。この効果は、実験データから、樹脂層の厚さが単繊維径の２倍以上必要であると推察される。一方で高強度・高剛性を得るために、高い繊維分率・低樹脂分率が必要であることから、繊維束を覆う樹脂層の厚さは、８〜３０μｍ、好ましくは、１０〜２０μｍである。従って、本発明には、単繊維の直径が５〜１０μｍである炭素繊維が、本発明の達成に好ましい態様である。
In the present invention, in a 1 mm × 1 mm cross section in the thickness direction of a molded product obtained by compression molding, in the carbon fiber cross section, m is the major axis of the fiber cross section, and n is the minor axis, its ellipticity n / m Each having a region of 0.8 to 1.0, a region of 0.4 to 0.6, and a region of 0.01 to 0.2, more preferably 100 or more, more preferably It is a preferable embodiment that 200 or more, particularly 500 or more have a fiber bundle region containing adjacent single fibers. A region can also be viewed as a layer. The ellipticity of a single fiber in cross section is a measure of the orientation of the single fiber axis. When the ellipticity is 1, it means that the single fiber is oriented perpendicular to the cross section of the molded product. Further, the smaller the ellipticity is, the substantially less than 0.1 means that the single fibers are oriented parallel to the cross section of the molded product. The case of 0.14 means 45 degrees with respect to the cross section of the molded product, and the case of 0.5 means that it is oriented at 60 degrees with respect to the cross section of the molded product. It is a preferable aspect that a single fiber bundle group in which the length axes of fibers having an ellipticity difference between adjacent single fibers is equal to or less than 10% of the average ellipticity forms a region. If the number of single fibers contained in each region is less than 100, fluidity and rigidity as a fiber bundle are not exhibited, which is not preferable for the present invention. In addition, there is a fiber bundle region in which the ellipticity is greatly different within a cross section of 1 mm × 1 mm in the thickness direction of the molded product. It means to become.
The short axis n of the cross section of the carbon fiber of the present invention is 4 to 10 μm, and preferably 5 to 9 μm. If the thickness is less than 4 μm, the rigidity of the single fiber is low, and the fiber axis tends to be bent, which is not preferable. On the other hand, if it exceeds 10 μm, the strength of the fiber is low, the effect of the present invention is small, and it is not preferable. The reason for this is not clear yet, but the present invention is easily achieved when the periphery of adjacent fiber bundles in which the directions of the fiber axes are aligned is covered with a resin layer. This is considered to be an effect of suppressing the entanglement and cutting of the carbon fiber during the flow during molding. This effect is presumed from the experimental data that the thickness of the resin layer needs to be twice or more the single fiber diameter. On the other hand, in order to obtain high strength and high rigidity, a high fiber fraction and a low resin fraction are required. Therefore, the thickness of the resin layer covering the fiber bundle is 8 to 30 μm, preferably 10 to 20 μm. is there. Therefore, in the present invention, a carbon fiber having a single fiber diameter of 5 to 10 μm is a preferable embodiment for achieving the present invention.
本発明には、熱可塑性樹脂２５〜５０質量％、好ましくは、３０〜４５質量％を含有する。５０質量％を超えると、炭素繊維の含有率が低くなり、複合した構造材の狙いの強度や弾性率に未達となるので好ましくない。また２５％未満では、炭素繊維の含浸不足となり、繊維の補強効果が発揮されず好ましくない。
本発明に使用される熱可塑性樹脂としては、線膨張係数が小さく、好ましくは１０×１０−５ｃｍ/ｃｍ/Ｋ以下であれば特に限定されない。例えば、ポリプロピレン、ポリメチルペンテン、ポリアミド６、ポリアミド６６、ポリアミドＭＸＤ６，ポリアミド１２、ポリアミド１１、ポリアミド６Ｔ共重合体、ポリフェニレンサルファイド、シンジオタクチックポリスチレン、ポリブチレンテレフタレート、ポリエチレンテレフタレート、ポリケトンやこれらの共重合体やポリマーアロイ体などが挙げられる。これらの中では、結晶部を含有するポリプロピレンやポリメチルペンテンのようなポリオレフィン樹脂やポリアミド６、ポリアミド６６、ポリアミドＭＸＤ６、ポリアミド６Ｔ共重合体などのポリアミド樹脂やポリフェニレンサルファイド樹脂が好ましい態様である。母相を成す熱可塑性樹脂の線膨張係数が高いと、複合材の局所的に、ある方向の寸法安定性が低下し、局所的寸法バラツキが大きくなり、内部応力を発現するので好ましくない。
In this invention, 25-50 mass% of thermoplastic resins, Preferably, 30-45 mass% is contained. If it exceeds 50% by mass, the carbon fiber content will be low, and the targeted strength and elastic modulus of the composite structural material will not be achieved. If it is less than 25%, carbon fiber impregnation is insufficient, and the reinforcing effect of the fiber is not exhibited, which is not preferable.
The thermoplastic resin used in the present invention is not particularly limited as long as it has a small linear expansion coefficient, preferably 10 × 10 −5 cm / cm / K or less. For example, polypropylene, polymethylpentene, polyamide 6, polyamide 66, polyamide MXD6, polyamide 12, polyamide 11, polyamide 6T copolymer, polyphenylene sulfide, syndiotactic polystyrene, polybutylene terephthalate, polyethylene terephthalate, polyketone and their co-polymers Examples include coalescence and polymer alloy. Among these, preferred are a polyolefin resin such as polypropylene and polymethylpentene containing a crystal part, a polyamide resin such as polyamide 6, polyamide 66, polyamide MXD6, and polyamide 6T copolymer, and a polyphenylene sulfide resin. When the linear expansion coefficient of the thermoplastic resin constituting the matrix is high, the dimensional stability in a certain direction of the composite material is locally lowered, the local dimensional variation is increased, and internal stress is generated, which is not preferable.
また本発明に使用される熱可塑性樹脂は、炭素繊維との接着性を高めるために、炭素繊維表面の活性基との化学反応性基や極性基を含有することが好ましい。例えば、極性基を有しないポリプロピレンやポリメチルペンテンやシンジオタクチックポリスチレンの場合、無水マレイン酸やイタコン酸のような不飽和酸やグリシジルメタクリレートのような不飽和エポキシによって変性されたものが好ましい。 In addition, the thermoplastic resin used in the present invention preferably contains a chemically reactive group or a polar group with an active group on the surface of the carbon fiber in order to enhance the adhesion to the carbon fiber. For example, in the case of polypropylene, polymethylpentene or syndiotactic polystyrene having no polar group, those modified with an unsaturated acid such as maleic anhydride or itaconic acid or an unsaturated epoxy such as glycidyl methacrylate are preferred.
更に、詳しくは、ポリプロピレンとしては、アイソタクチックポリプロピレンのホモタイプ、ブロックタイプ、シンジオタクチックポリプロピレンなどが使用される。結晶性の低いアタクチックポリプロピレンは、複合材の成形加工性に劣るので本発明には好ましくない。ポリプロピレンにポリエチレンやポリブテンなど他のポリオレフィンがブロック共重合されたブロックタイプポリプロピレンも本発明に使用される。特に、耐衝撃性が要求される構造材用複合材料には好ましい態様である。本発明の複合材料においては、さらに未変性ポリプロピレンを配合することでも本発明の目的は達成される。特に、使用される無水マレイン酸変性ポリプロピレンのメルトフローレートが１００ｇ／１０ｍｉｎを越える場合、より高分子量の未変性ポリプロピレンをブレンドすることにより、混合体のメルトフローレートを３０〜１２０ｇ／１０ｍｉｎに、好ましくは４０〜１００ｇ／１０ｍｉｎに調節することが好ましい。工業的に好ましい態様である。変性体と未変性体の合計質量に対して、無水マレイン酸変性量は、０．０１〜４質量％、好ましくは０．０２〜３質量％であり、変性体と未変性体の比率は、４：６〜０．５：９．５が、さらに好ましくは、２：８〜０．７：９．３である。変性体に対する未変性体の比が４：６未満では経済的効果が小さく、０．５：９．５を超えると炭素繊維とポリプロピレンの界面に対して変性体が不足して欠陥点となることがあり好ましくない。 More specifically, isotactic polypropylene homotype, block type, syndiotactic polypropylene and the like are used as polypropylene. Atactic polypropylene having low crystallinity is not preferable for the present invention because it is inferior in molding processability of the composite material. A block type polypropylene obtained by block copolymerization of other polyolefin such as polyethylene and polybutene with polypropylene is also used in the present invention. In particular, it is a preferred embodiment for composite materials for structural materials that require impact resistance. In the composite material of the present invention, the object of the present invention can also be achieved by further blending unmodified polypropylene. In particular, when the melt flow rate of the maleic anhydride-modified polypropylene used exceeds 100 g / 10 min, the melt flow rate of the mixture is preferably 30 to 120 g / 10 min by blending higher molecular weight unmodified polypropylene. Is preferably adjusted to 40 to 100 g / 10 min. This is an industrially preferred embodiment. The maleic anhydride modification amount is 0.01 to 4% by mass, preferably 0.02 to 3% by mass, based on the total mass of the modified product and the unmodified product. 4: 6 to 0.5: 9.5 is more preferably 2: 8 to 0.7: 9.3. If the ratio of the unmodified product to the modified product is less than 4: 6, the economic effect is small, and if it exceeds 0.5: 9.5, the modified product is insufficient with respect to the interface between the carbon fiber and the polypropylene, resulting in a defect point. Is not preferable.
本発明に使用される熱可塑性樹脂は、融点より３０℃高い温度における２１．２Ｎ荷重下のメルトフローレートが、３０〜１５０ｇ／１０ｍｉｎが好ましく、５０〜１４０ｇ／１０ｍｉｎが特に好ましい。３０ｇ／１０ｍｉｎ未満では、繊維への含浸性が低く、空隙率が高くなり好ましくない。また１５０ｇ／１０ｍｉｎを超えると、複合材料の溶融加工時、樹脂と繊維が分離しやすく好ましくない。 The thermoplastic resin used in the present invention preferably has a melt flow rate under a 21.2N load at a temperature 30 ° C. higher than the melting point of 30 to 150 g / 10 min, particularly preferably 50 to 140 g / 10 min. If it is less than 30 g / 10 min, the impregnation property to the fiber is low, and the porosity is high, which is not preferable. Moreover, when it exceeds 150 g / 10min, at the time of the melt processing of a composite material, it is easy to isolate | separate resin and fiber, and is not preferable.
熱可塑性樹脂と炭素繊維の複合化の方法は特に限定されない。炭素繊維束と熱可塑性樹脂フイルムを積層し、フイルムを加熱溶融して炭素繊維束に含浸する方法や、開繊した炭素繊維束を引き揃えて、その表面に押出機のダイヘッドから溶融樹脂に供給し、加圧含浸することでプリプレグテープやプリプレグストランドとする方法などが例示される。
プリプレグテープやプリプレグストランドを、７．５ｍｍ〜１００ｍｍにカットして得られる短冊やペレットを平板成形用金型内にランダムにばら撒き、加熱・圧縮してプリプレグシート化する。また予め炭素繊維束を７．５ｍｍ〜１００ｍｍにカットしてチョップドストランドを、平面上にランダムにばら撒き、部分的にサイジング剤を溶融して得られたチョップドストランドマットに、熱可塑性樹脂フイルムを積層し、加熱圧縮し、含浸した後、冷却固化する方法や、チョップドストランドマット表面に押出機やニーダーで加熱溶融した熱可塑性樹脂を供給し、加圧含浸してプリプレグシート化する方法などが上げられる。
プリプレグシート層とプリプレグテープやプリプレグストランドを一軸方向や直交に、多軸方向に並べた層や織った層を組み合わせ積層した複合材とすることもできる。
The method for combining the thermoplastic resin and the carbon fiber is not particularly limited. A method of laminating a carbon fiber bundle and a thermoplastic resin film, heating and melting the film to impregnate the carbon fiber bundle, and arranging the opened carbon fiber bundle together on the surface and supplying the molten resin from the die head of the extruder And the method etc. which are made into a prepreg tape or a prepreg strand by carrying out pressure impregnation are illustrated.
Strips and pellets obtained by cutting a prepreg tape or prepreg strand to 7.5 mm to 100 mm are randomly dispersed in a flat plate mold, heated and compressed to form a prepreg sheet. The thermoplastic fiber film is laminated on the chopped strand mat obtained by cutting the carbon fiber bundle to 7.5 mm to 100 mm in advance and randomly dispersing the chopped strands on a flat surface and partially melting the sizing agent. The method of cooling and solidifying after heat compression and impregnation, the method of supplying a thermoplastic resin heated and melted by an extruder or kneader to the chopped strand mat surface, and pressurizing and impregnating to a prepreg sheet, etc. .
A prepreg sheet layer, a prepreg tape, and a prepreg strand may be combined and laminated in a uniaxial direction or a perpendicular direction and a multi-axial layer or a woven layer.
本発明のプリプレグシート（予備成形体）や複合材は、赤外線加熱や高周波加熱して、樹脂を加熱溶融して、圧縮成形機の金型に供給して、賦形冷却後脱型して構造材の部品（成形品）が成形される。その成形条件は特に限定されない。たとえば予備成形体を母相の融点や軟化点以上、好ましくは、その温度より３０℃以上、好ましくは４０℃以上まで加熱し、それを母相の融点や軟化点以下、好ましくはその温度より３０℃以下、好ましくは４０℃以下の圧縮成形用金型に供給し、冷却固化する方法が好ましい態様である。また母相の融点未満の予備成形体を融点以上に加熱された金型に供給し、金型からの伝熱で予備成形体を加熱し圧縮成形後、金型を融点以下まで冷却して成形品を取り出すこともできる。いずれの方法においても、本発明の効果は発揮される。 The prepreg sheet (preliminary molded body) and composite material of the present invention have a structure in which infrared heating or high-frequency heating is performed, the resin is heated and melted, supplied to a mold of a compression molding machine, and is removed after shaping cooling. A material part (molded product) is formed. The molding conditions are not particularly limited. For example, the preform is heated to a melting point or softening point of the parent phase or higher, preferably 30 ° C. or higher, preferably 40 ° C. or higher from the temperature. A preferred embodiment is a method in which the mixture is supplied to a compression mold at a temperature of ℃ or less, preferably 40 ℃ or less, and is cooled and solidified. Also, a preform with a melting point lower than the melting point of the matrix phase is supplied to a mold heated to a temperature higher than the melting point. After the preform is heated by heat transfer from the mold and compression molding is performed, the mold is cooled to below the melting point and molded. Goods can be taken out. In any method, the effect of the present invention is exhibited.
本発明によるプリプレグシートは、等方的に高い流動性を有するから、成形前のブランクの形状は特に限定されず、自由度が高いことも本発明の特徴のひとつである。本発明の狙いを効果的に達成するには、プリプレグシートの水平投影面積は、目的とする成形品の水平投影面積の０．７〜０．９９倍、好ましくは０．８５〜０．９９倍が好ましい。特に０．９０から０．９９が好ましい。０．７倍未満では、金型内での流動距離が長くなり、炭素繊維の長さ軸方向が配向することで異方性が発現することがあり、好ましくない。また０．９９を超えると、成形時、成形圧の上昇が速く、内部の均一化が進みにくく好ましくない。またリブやボスのある箇所や立ち面のある成形品においては、その近傍にプリプレグシートを追加することが好ましい。
プリプレグシートの厚さは、１ｍｍ〜１０ｍｍ、好ましくは１．２〜７ｍｍである。１ｍｍ未満では、流動抵抗が大きく好ましくなく。また１０ｍｍを超えると、成形前予備過熱した場合、内部と表層部の温度差が大きく、流動が不均一となりやすく好ましくない。
Since the prepreg sheet according to the present invention has isotropic high fluidity, the shape of the blank before molding is not particularly limited, and a high degree of freedom is also one of the features of the present invention. In order to effectively achieve the aim of the present invention, the horizontal projection area of the prepreg sheet is 0.7 to 0.99 times, preferably 0.85 to 0.99 times the horizontal projection area of the target molded product. Is preferred. In particular, 0.90 to 0.99 is preferable. If it is less than 0.7 times, the flow distance in the mold becomes long, and anisotropy may be manifested by orienting the longitudinal direction of the carbon fiber, which is not preferable. On the other hand, if it exceeds 0.99, the molding pressure rises rapidly during molding, and internal homogenization is difficult to proceed. In addition, in a molded product having a rib or boss or a standing surface, it is preferable to add a prepreg sheet in the vicinity thereof.
The thickness of the prepreg sheet is 1 mm to 10 mm, preferably 1.2 to 7 mm. If it is less than 1 mm, the flow resistance is unfavorably large. On the other hand, if it exceeds 10 mm, when preheating is performed before molding, the temperature difference between the inside and the surface layer is large, and the flow tends to be nonuniform, which is not preferable.
本発明のプリプレグシートには、上記の必須成分の他に物性改良・成形性改良、耐久性改良を目的として、結晶核剤・離型剤、滑剤、酸化防止剤、難燃剤、耐光剤、耐候剤などが配合できる。 In addition to the above essential components, the prepreg sheet of the present invention has a crystal nucleating agent / mold releasing agent, a lubricant, an antioxidant, a flame retardant, a light resistance agent, a weather resistance, for the purpose of improving physical properties, moldability, and durability. Agents can be added.
本発明のプリプレグシート（予備成形体）や複合材から得られた成形部品は、自動車のフレーム、二輪車のフレーム、農機具のフレーム、ＯＡ機器のフレーム、機械部品など高い強度と剛性の必要な部品に利用される。 Molded parts obtained from the prepreg sheet (preliminary molded product) or composite material of the present invention can be used for parts that require high strength and rigidity, such as automobile frames, motorcycle frames, agricultural equipment frames, OA equipment frames, and machine parts. Used.
以下に実施例を示して本発明を具体的に説明するが、本発明は実施例に限定されるものではない。 EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the examples.
［１］成形品断面の単繊維切り口の楕円度観察方法
成形品断面の繊維の分布状態や繊維軸の配向状態は、３００×３００×３ｍｍの成形品中央部から１０×１０ｍｍの大きさに切り出し、厚さ方向の断面を上に水平になるようにセットしエポキシ樹脂（シェル化学社製エポン８１２）で包埋した。エポキシ樹脂が硬化したあと、この上面をリファインテック社製ＡＰＵ１３８型を使用して、回転砥石で研磨し断面を平滑にした。得られた平滑面について、デジタルマイクロスコープＶＨ−Ｚ１００Ｒ型（キーエンス社製）を使用して、落射照明により４００倍に拡大して断面を厚さ方向に線状トレースして写真撮影した。単繊維断面がほぼ同じ楕円度を持つ範囲を仕分け、それを１層と数え、１層内の本数が１００本以上有するか数えた。各層毎に１００本以上の単繊維断面の短径と長径を測定し、単繊維毎の楕円度（短径／長径）を求め、その平均をその繊維束の楕円度とした。平均楕円度が（１）〜（３）式に該当する繊維束の有無または繊維束数（層数）を数えた。
[1] Method for observing ellipticity of single fiber cut surface of molded product cross section Fiber distribution state and fiber axis orientation state of the cross section of molded product are cut out to a size of 10 × 10 mm from the center of the molded product of 300 × 300 × 3 mm Then, the cross section in the thickness direction was set so as to be horizontal, and embedded in an epoxy resin (Epon 812 manufactured by Shell Chemical Co., Ltd.). After the epoxy resin was cured, the upper surface was polished with a rotating grindstone using an APU138 type manufactured by Refine Tech Co., Ltd. to smooth the cross section. Using the digital microscope VH-Z100R type (manufactured by Keyence Corporation), the obtained smooth surface was magnified 400 times by epi-illumination, and the cross section was linearly traced in the thickness direction and photographed. A range in which the single fiber cross-sections have approximately the same ellipticity was sorted, counted as one layer, and counted whether there were 100 or more in one layer. For each layer, the short diameter and long diameter of 100 or more single fibers were measured, the ellipticity (short diameter / long diameter) of each single fiber was determined, and the average was defined as the ellipticity of the fiber bundle. The presence or absence of fiber bundles or the number of fiber bundles (number of layers) corresponding to the average ellipticity in the formulas (1) to (3) were counted.
［２］線膨張係数測定
プリプレグシートまたは成形品の中央部から縦方向約８ｍｍ×横方向約８ｍｍを切削した。それぞれの成形品の縦方向や横方向の両断面が平行になるように、１０００番のサンドペーパーにて研磨し、線膨張係数測定の試験片とした。
切り出した試験片を２３℃に温度調節された試験室中のデシケーター中で４８時間保管した後、試験規格ＩＳＯ１１３５９−２に準じ、理学電機社製熱物理試験機ＴＭＡを使用し、１ｍｍφのプローベ上に３ｇの荷重を掛け、０℃まで冷却後１０℃／分にて１２０℃まで加熱し、プローベの変位を測定した。
２０℃から１００℃間の変位から次式により線膨張係数を求めた
β＝（Ｘ１２０−Ｘ２０）／（１２０−２０）／Ｌ
ここで、β：線膨張係数、Ｌ：試験片高さ、Ｘ１２０：１２０℃におけるプローベ位置、Ｘ２０：２０℃にけるプローベ位置である。
[2] Linear expansion coefficient measurement About 8 mm in the vertical direction × about 8 mm in the horizontal direction was cut from the center of the prepreg sheet or molded product. Each molded product was polished with sand sand No. 1000 so that both the vertical and horizontal cross sections thereof were parallel to each other, and a test piece for measuring the linear expansion coefficient was obtained.
The cut specimen is stored for 48 hours in a desiccator in a test room whose temperature is adjusted to 23 ° C., and then on a 1 mmφ probe using a thermal physical testing machine TMA manufactured by Rigaku Corporation in accordance with test standard ISO11359-2. A load of 3 g was applied to the sample, cooled to 0 ° C., heated to 120 ° C. at 10 ° C./min, and the probe displacement was measured.
The coefficient of linear expansion was calculated from the displacement between 20 ° C. and 100 ° C. by the following equation: β = (X 120 −X 20 ) / (120−20) / L
Here, β: linear expansion coefficient, L: test piece height, X 120 : probe position at 120 ° C., X 20 : probe position at 20 ° C.
実施例１
６０００本の炭素繊維からなるロービング（東邦テナックス社ＩＭＳ４０）を４ｋｇ／Ｈになる速度で拡張開繊して含浸台のダイヘッドに供給した。変性ポリプロピレン樹脂ＭＡＨ００３（２３０℃、２１．２Ｎ荷重下のメルトフローレート５０ｇ／１０ｍｉｎ）を，２６０℃に温度調節されたスクリュー式押し出し機のホッパーに投入し、溶融樹脂をギアポンプにより２ｋｇ／Ｈを計量して、含浸台のダイヘッドに供給した。含浸台で加圧含浸、脱泡後、幅１０ｍｍ・高さ０．２ｍｍのダイから含浸被覆されたテープ状プリプレグを押し出し、空冷固化した後、枷に巻き取った。（炭素繊維 ５５質量％、樹脂４５質量％）
得られたプリプレグテープを３５ｍｍにカットし、短冊状のプリプレグテープを３００ｍｍ×３００ｍｍの平板状の型内にランダムにばらまき供給した。型を２８０℃まで加熱した後、圧縮し、３分間保持後、型を１２０℃低温まで冷却して、炭素繊維がランダム配向したプリプレグシートを得た。
強化材がランダム配向した厚さ３．１ｍｍのプリプレグシートの中央部から、２９０ｍｍ×２９０ｍｍのブランクを切削した。このブランクを、予め遠赤外線ヒータにて２５０℃まで予熱し、圧縮成形機（神藤金属工業所製、５０ｔ）に取り付け、予め１５０℃に温度調節した３００ｍｍ×３００ｍｍのキャビティを有する金型に供給し、３０ＭＰａにて３分間圧縮成形し、３００×３００×３ｍｍの平板成形品を得た。
圧縮成形により得られた平板成形品１０枚のそれぞれの中央部から縦方向約８ｍｍ×横方向約８ｍｍを切削した。それぞれの成形品の縦方向や横方向の両断面が平行になるように、１０００番のサンドペーパーにて研磨し、線膨張係数評価用試験片とした。
上記［１］により、断面の短繊維の楕円度を求めて、各層の繊維束に短繊維が１００本以上有することを確認し、該当楕円度の有無及び各層の数を数えた。また上記［２］により２０℃から１００℃間の変位から次式により線膨張係数を求めた。
成形品の直交する２方向の線膨張係数は、−０．０３×１０−５ｃｍ／ｃｍ／Ｋと−０．０４×１０−５ｃｍ／ｃｍ／Ｋとほぼ０に近く，２０℃と１２０℃の寸法は殆ど変わっていなかった。
Example 1
A roving made of 6000 carbon fibers (Toho Tenax Co., Ltd. IMS40) was expanded and opened at a rate of 4 kg / H and supplied to the die head of the impregnation table. Modified polypropylene resin MAH003 (230 ° C, melt flow rate under 21.2N load 50g / 10min) is put into the hopper of a screw-type extruder adjusted to 260 ° C, and the molten resin is weighed 2kg / H with a gear pump. Then, it was supplied to the die head of the impregnation table. After pressure impregnation and defoaming on an impregnation stand, the tape-like prepreg coated with impregnation was extruded from a die having a width of 10 mm and a height of 0.2 mm, air-cooled and solidified, and then wound on a basket. (55% carbon fiber, 45% resin)
The obtained prepreg tape was cut into 35 mm, and the strip-shaped prepreg tape was randomly distributed and supplied into a plate-shaped mold of 300 mm × 300 mm. The mold was heated to 280 ° C., compressed, held for 3 minutes, and then the mold was cooled to a low temperature of 120 ° C. to obtain a prepreg sheet in which carbon fibers were randomly oriented.
A blank of 290 mm × 290 mm was cut from the center of a prepreg sheet having a thickness of 3.1 mm in which reinforcing materials were randomly oriented. This blank is preheated to 250 ° C. with a far-infrared heater in advance, attached to a compression molding machine (manufactured by Shinfuji Metal Industry Co., Ltd., 50 t), and supplied to a mold having a 300 mm × 300 mm cavity whose temperature is adjusted to 150 ° C. And compression molding at 30 MPa for 3 minutes to obtain a 300 × 300 × 3 mm flat plate molded product.
About 10 mm in the vertical direction and about 8 mm in the horizontal direction were cut from the center of each of the 10 flat molded articles obtained by compression molding. The molded product was polished with sandpaper No. 1000 so that both the vertical and horizontal cross-sections of each molded product were parallel to obtain a test piece for evaluating the linear expansion coefficient.
According to the above [1], the ellipticity of the short fibers of the cross section was obtained, and it was confirmed that the fiber bundle of each layer had 100 or more short fibers, and the presence or absence of the corresponding ellipticity and the number of each layer were counted. Further, the linear expansion coefficient was obtained from the displacement between 20 ° C. and 100 ° C. by the following equation according to [2].
The linear expansion coefficients of the two orthogonal directions of the molded product are −0.03 × 10 −5 cm / cm / K and −0.04 × 10 −5 cm / cm / K, which are close to 0, 20 ° C. and 120 ° C. The dimensions in degrees Celsius were almost unchanged.
実施例２〜７
プリプレグ用の熱可塑性樹脂の種類と分率や該プリプレグシートやプリプレグストランドを積層し成形して得られた成形品の各積層面における繊維軸の配向の厚さ方向の組み合わせの構成（ランダム：面内で繊維軸がランダム配向、直交：ある層の繊維軸に対して他層の繊維は直交している、一方向：各層の繊維軸は同じ方向になっている）を表１に示したように変更した以外は、実施例１と全く同様にプリプレグを作製した後、平板成形品を成形した。平板成形品から実施例１と全く同様に，試験片を切削し、表面を研磨後、実施例１と全く同様にして線膨張係数を測定し、表１に示した。
成形品中の直交する２方向の線膨張係数はすべて−０．１１〜−０．４４×１０−５ｃｍ／ｃｍ／Ｋの範囲にあった。
Examples 2-7
Composition of the thickness direction of the orientation of the fiber axis on each laminated surface of the molded product obtained by laminating and molding the prepreg thermoplastic resin for the prepreg and the prepreg sheet or prepreg strand (random: surface In Table 1, the fiber axes are randomly oriented, orthogonal: the fibers of the other layer are orthogonal to the fiber axis of one layer, and one direction: the fiber axes of each layer are in the same direction. A prepreg was produced in the same manner as in Example 1 except that the flat molded product was formed. A test piece was cut from a flat molded product in the same manner as in Example 1, and after polishing the surface, the linear expansion coefficient was measured in the same manner as in Example 1 and shown in Table 1.
The linear expansion coefficients in two orthogonal directions in the molded product were all in the range of −0.11 to −0.44 × 10 −5 cm / cm / K.
比較例１〜７
強化繊維として、ガラス繊維を使用することや、繊維分率を変更した以外は、実施例１と全く同様にしてプリプレグテープを得た。そのプリプレグテープやこれに強化繊維の一軸や直交や多軸配向品を組み合わせ、実施例１と全く同様に成形して、平板成形品を得、同様にその線膨張係数を測定し、表２に示した。
比較例１や２において、炭素繊維をガラス繊維に変更すると、直交する線膨張係数は、共に０．５×１０−５ｃｍ／ｃｍ／Ｋを超え、寸法変化が大きくなった。比較例３において、樹脂分率が５５質量％となると、線膨張係数は０．６４×１０−５ｃｍ／ｃｍ／Ｋと０．６７×１０−５ｃｍ／ｃｍ／Ｋと高くなった。また比較例４において、樹脂分率が２０質量％となると、−０．６０×１０−５ｃｍ／ｃｍ／Ｋ以上となり大きな収縮を示した。比較例５において、一方向性積層の場合、繊維方向は−０．７８×１０−５ｃｍ／ｃｍ／Ｋ、直角方向は５．５７×１０−５ｃｍ／ｃｍ／Ｋとそれぞれ正負の高い線膨張係数を示し、大きな異方性を示した。また非強化の場合、直交する両方向共８×１０−５ｃｍ／ｃｍ／Ｋ以上と高い線膨張係数を示した。
Comparative Examples 1-7
A prepreg tape was obtained in the same manner as in Example 1 except that glass fiber was used as the reinforcing fiber and the fiber fraction was changed. The prepreg tape and the uniaxial, orthogonal or multiaxially oriented product of the reinforcing fiber are combined with the prepreg tape and molded in exactly the same manner as in Example 1 to obtain a flat molded product. Similarly, the linear expansion coefficient is measured, and Table 2 shows Indicated.
In Comparative Examples 1 and 2, when the carbon fiber was changed to glass fiber, the orthogonal linear expansion coefficients both exceeded 0.5 × 10 −5 cm / cm / K, and the dimensional change was large. In Comparative Example 3, when the resin fraction was 55% by mass, the linear expansion coefficients were as high as 0.64 × 10 −5 cm / cm / K and 0.67 × 10 −5 cm / cm / K. Further, in Comparative Example 4, when the resin fraction was 20% by mass, it was −0.60 × 10 −5 cm / cm / K or more, indicating a large shrinkage. In Comparative Example 5, in the case of unidirectional lamination, the fiber direction is −0.78 × 10 −5 cm / cm / K, and the perpendicular direction is 5.57 × 10 −5 cm / cm / K, which is a high positive and negative line. It showed an expansion coefficient and a large anisotropy. In the case of non-strengthening, the linear expansion coefficient was as high as 8 × 10 −5 cm / cm / K or more in both orthogonal directions.
実験に使用した原料と記号：
Ｔ８０２：ポリアミド樹脂 ＰＡ６（東洋紡社製、２５０℃におけるＭＦＲ ７３ｇ／１０ｍｉｎ，融点２２７℃）
ＭＡＨ００３：ポリプロピレンＷ１０１（住友化学社製）９８．５質量部に、ジクミルパーオキサイド（日本油脂社製パークミルＤ）０．５質量部、粉末化した無水マレイン酸（ナカライテスク社製）２質量部を予備混合して、１９０℃に温度調節された二軸押出機のホッパーに供給して、スクリュウ８０回転／分にて溶融反応して得たストランドを水槽で冷却固化して得られた無水マレイン酸変性ポリプロピレン（ＭＦＲ５０ｇ／ｍｉｎ）、融点１６５℃
ＥＭＣ７００：ポリブチレンテレフタレート（東洋紡社製、２５０℃におけるＭＦＲ６０ｇ／１０ｍｉｎ、融点２２５℃）
ＴＳ００１：ポリフェニレンスルフィド（東洋紡社製、３００℃におけるＭＦＲ７８ｇ／１０ｍｉｎ，融点２８４℃）
ＧＦ−Ｒ：ガラス繊維ロービング、(日本電気硝子社製、ＡＲ２５００Ｈ−１０３，３１ストランド)
ＣＦ−Ｒ：炭素繊維、帝人社製東邦テナックス ＩＭＳ４０（単繊維径６．４μｍ、６０００フィラメント）
Raw materials and symbols used in the experiment:
T802: Polyamide resin PA6 (manufactured by Toyobo Co., Ltd., MFR at 250 ° C. 73 g / 10 min, melting point 227 ° C.)
MAH003: Polypropylene W101 (manufactured by Sumitomo Chemical Co., Ltd.) 98.5 parts by mass, dicumyl peroxide (Nippon Yushi Co., Ltd. Park Mill D) 0.5 parts by mass, powdered maleic anhydride (manufactured by Nacalai Tesque) 2 parts by mass An anhydrous maleate obtained by cooling and solidifying a strand obtained by melting and reacting with a screw at a speed of 80 revolutions / minute by feeding to a hopper of a twin screw extruder whose temperature is adjusted to 190 ° C. Acid-modified polypropylene (MFR 50 g / min), melting point 165 ° C.
EMC700: Polybutylene terephthalate (Toyobo Co., Ltd., MFR 60 g / 10 min at 250 ° C., melting point 225 ° C.)
TS001: Polyphenylene sulfide (manufactured by Toyobo Co., Ltd., MFR 78 g / 10 min at 300 ° C., melting point 284 ° C.)
GF-R: Glass fiber roving (manufactured by Nippon Electric Glass Co., Ltd., AR2500H-103, 31 strands)
CF-R: carbon fiber, Toho Tenax IMS40 manufactured by Teijin Ltd. (single fiber diameter 6.4 μm, 6000 filament)
本発明により、高い強度や弾性率を有するにも関わらず、面内の線膨張係数が等方であり、かつ絶対値が極めて小さく、高い寸法精度と熱に対する寸法安定性を有する高強度成形品が提供される。従って、これまでできなかった金属製精密機械部品や構造部材の樹脂化が可能になった。 According to the present invention, in spite of having high strength and elastic modulus, the in-plane linear expansion coefficient is isotropic, the absolute value is extremely small, and high strength molded product having high dimensional accuracy and dimensional stability against heat. Is provided. Accordingly, it has become possible to convert metal precision mechanical parts and structural members that have not been possible until now.
Claims (2)
前記熱可塑性樹脂と前記炭素繊維の繊維束からなるプリプレグテープまたはプリプレグストランドを、一軸方向に並べた層、直交方向に並べた層、または織った層を
組合せた成形品であって、その成形品の面内の任意の直交する２方向の線膨張係数が、共に−０．５×１０−５〜０．５×１０−５ｃｍ／ｃｍ／Ｋの範囲であり、
成形品の厚さ方向断面（１ｍｍ×１ｍｍ）内において、炭素繊維の断面における長軸ｍに対する短軸ｎの比で表される楕円度ｎ／ｍが（１）式、（２）式、及び（３）式をそれぞれ満たす異方向に配向した単繊維を、それぞれ１００本以上含む繊維束領域を含有することを特徴とする炭素繊維強化熱可塑性樹脂成形品。
０．８≦ｎ／ｍ≦１．０ （１）
０．４≦ｎ／ｍ≦０．６ （２）
０．０１≦ｎ／ｍ≦０．２ （３） A layer of a prepreg sheet containing 25 to 50% by mass of a thermoplastic resin and 50 to 75% by mass of carbon fibers having a length of 7.5 to 100 mm ;
A layer in which the prepreg tape or prepreg strand comprising the thermoplastic resin and the carbon fiber bundle is arranged in a uniaxial direction, a layer arranged in an orthogonal direction, or a woven layer.
A molded article in combination, any of the linear expansion coefficient of the two orthogonal directions in the plane of that formed molded article are both -0.5 × 10 -5 ~0.5 × 10 -5 cm / cm / range der of K is,
Within the cross section (1 mm × 1 mm) in the thickness direction of the molded product, the ellipticity n / m represented by the ratio of the short axis n to the long axis m in the cross section of the carbon fiber is expressed by the formulas (1), (2), and (3) the single fibers oriented in different directions meet each carbon fiber reinforced thermoplastic tree AburaNaru molded article characterized that you containing fiber bundle region containing more than 100, respectively.
0.8 ≦ n / m ≦ 1.0 (1)
0.4 ≦ n / m ≦ 0.6 (2)
0.01 ≦ n / m ≦ 0.2 (3)
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| JP2019508292A (en) * | 2016-02-19 | 2019-03-28 | カーボン コンバージョンズ インコーポレイテッド | Thermoplastic bonded preform and thermosetting matrix formed using the same |
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