JP2011089060A - Fiber-reinforced resin composite material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reinforcing short fiber capable of making a fiber-reinforced resin composite material having a high strength, high impact resistance and abrasion resistance without inhibiting the workability in the time of kneading raw materials and mold-processing, and to provide the fiber-reinforced resin composite containing the short fiber. <P>SOLUTION: The fiber-reinforced resin composite is characterized by including the fiber satisfying the following requirements. (a) The single fiber diameter is 20 to 100 μm, and the fiber length is 0.8 to 15 mm. (b) The tensile strength is ≥2,500 MPa, the tensile elastic modulus is ≥50 GPa and the elongation at break is within a 3 to 8% range. (c) The density is ≤1.5 g/cm<SP>3</SP>. (d) The thermal degradation-starting temperature is ≥300°C. (e) The fiber-mixing ratio is ≥1 vol.%. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a fiber reinforced resin composite used mainly in structures, mechanisms, and sliding members including automobiles and electric parts.

  Conventionally, metal materials such as steel have been generally used as materials for structures and mechanism parts including automobiles and electrical parts, especially in applications where high loads are applied. The demand for materials has become more and more strict as the performance and performance have improved, and recently, materials using fiber reinforced resin composites have been studied.

  The physical properties of the fiber reinforcing material of such a fiber reinforced resin composite include heat resistance that can withstand immersion in a lubricating oil at 100 to 130 ° C., such as a molding temperature during resin molding, or a timing gear used in an automobile engine. In recent years, since the load applied to the structural member for the vehicle is further increased, it is also required to have higher strength and higher shock absorption.

As such a fiber reinforcing material, conventionally, a textile fabric using a meta-type aromatic polyamide fiber is known (Patent Document 1), but the meta-type aromatic polyamide fiber is excellent in moldability. Since the strength is inferior, there is a problem in terms of safety in applications where high loads are applied.
In order to solve such a problem, a mixed woven fabric in which a meta-type aromatic polyamide fiber and a carbon fiber are combined is disclosed as a reinforcing material (Patent Document 2). However, since the carbon fiber has low impact strength, There has been a problem that the fiber reinforced resin composite is damaged during cutting or use.

Furthermore, a nonwoven fabric in which a meta-type aromatic polyamide fiber excellent in moldability and a high-strength para-type aromatic polyamide fiber are combined is disclosed as a reinforcing material (Patent Document 3).
Although it is certainly effective to some extent, when used as a gear for automobiles etc., it is not necessarily sufficient physical properties when used in a higher temperature atmosphere or increased load due to recent high-speed rotation, There existed a problem that the process of using a nonwoven fabric was needed and the yield fell.

JP-A-2-241729 Japanese Patent Laid-Open No. 5-240325 JP-A-7-113458

  Accordingly, an object of the present invention is to provide a fiber reinforced resin composite obtained by kneading with a resin without forming the fiber into a fiber structure such as a woven fabric or a nonwoven fabric.

  As a result of intensive studies, the present inventors have determined that a desired fiber-reinforced resin composite can be obtained by using a fiber having a specific fiber shape and mechanical properties as a reinforcing material. Reached.

That is, according to the present invention,
A fiber reinforced resin composite comprising fibers that satisfy the following requirements;
a) The single yarn fiber diameter is 20 to 100 μm, and the fiber length is 0.8 to 15 mm.
b) The tensile strength is 2500 MPa or more, the tensile modulus is 50 GPa or more, and the elongation at break is in the range of 3 to 8%.
c) The density is 1.5 g / cm ³ or less.
d) The thermal decomposition starting temperature is 300 ° C. or higher.
e) The fiber mixing rate is 1% by volume or more.
Preferably, a fiber reinforced resin composite in which the fiber is polyparaphenylene terephthalamide fiber and / or copolyparaphenylene 3,4'-oxydiphenylene terephthalamide fiber,
Is provided.

  The fiber reinforced resin composite of the present invention is a fiber reinforced resin composite imparted with high strength, high impact resistance, high heat resistance, and high wear resistance, and has a specific fineness and length (aspect ratio), By using fibers having strength and density, workability such as entanglement of the reinforcing fibers is not hindered during kneading and molding of the resin and fibers, and can be easily dispersed into a molded body.

The present invention is illustrated by the following preferred examples, but is not limited thereto.
The fiber length of the (reinforcing material) fiber used in the fiber-reinforced resin composite of the present invention is 0.8 to 15 mm, preferably 0.9 to 10 mm, more preferably 1 to 6 mm, and the fiber diameter is 20 to 100 μm, preferably Must be 30 to 80 μm, more preferably 40 to 70 μm. When the fiber length of the fiber is less than 0.8 mm or the fiber diameter exceeds 100 μm, the fibers are uniformly dispersed, but the adhesion with the resin is insufficient and the strength and durability are poor.
Conversely, if the fiber length exceeds 15 mm or the fiber diameter is less than 20 μm, the fibers are entangled, and the fibers are not uniformly present in the resin, so that a sufficient reinforcing effect cannot be obtained.

  The fiber used in the fiber reinforced resin composite of the present invention needs to have a high strength, a high elastic modulus, and an appropriate elongation at break. Specifically, the tensile strength of the fiber is 2500 MPa. As described above, it is preferable that the tensile elastic modulus is 50 GPa or more and the elongation at break of the fiber is in the range of 3 to 8%.

  If the tensile strength of the fiber is less than 2500 MPa or the tensile elastic modulus is less than 50 GPa, the bending strength of the fiber reinforced resin composite decreases, and when the load is applied to the fiber reinforced resin composite, the fiber breaks. The shock cannot be absorbed sufficiently. Conversely, in order to obtain a predetermined reinforcing effect, the amount of added fiber must be increased, and the fiber dispersion state becomes non-uniform. The tensile strength of the fiber is preferably 3000 MPa or more, and the tensile elastic modulus is 60 GPa or more.

  If the breaking elongation of the fiber is less than 3%, the toughness of the fiber-reinforced resin composite is not sufficient. Further, if the elongation at break exceeds 8%, the difference in elongation from the resin as the base material becomes too large, and the interfacial adhesion in the vicinity of the fracture surface of the fiber reinforced resin composite due to the decrease in the thickness of the single fiber due to elongation. Partial peeling easily occurs at the portion, and the reinforcing effect cannot be sufficiently exhibited.

The density of the fiber is preferably less than 1.5 g / cm ³ from the viewpoint of weight reduction of the fiber reinforced resin composite. In addition, when fibers of the same fiber diameter and fiber length as those used in the past are mixed in the same volume in the resin, the smaller the density, the greater the number of fibers and the more effective the superior reinforcing performance. Expression is expected.

  Fibers used in the fiber reinforced resin composite include inorganic fibers such as carbon fiber, glass fiber, ceramic fiber, steel fiber, asbestos fiber, aramid fiber, vinylon fiber, polypropylene fiber, polyethylene fiber, polyarylate fiber, polybenz Any of organic fibers such as oxazole (PBO) fiber, nylon fiber, polyester fiber, polyketone fiber, acrylic fiber, vinyl chloride fiber, cellulose fiber, and pulp fiber can be used. Of these, fibers made of para-type aramid are preferable because they have a greater reinforcing effect than other fibers. Especially, copolyparaphenylene-3,4'oxydiphenylene-terephthalamide fibers are excellent in chemical resistance and can be used in high-temperature and high-pressure atmospheres. Even if it is held for a long time, the deterioration of the mechanical properties is small and it is preferable because it has a high strength retention.

  Further, the fiber mixing ratio of the fibers can be determined in consideration of the moldability and processability of the fiber reinforced resin composite, but it is necessary to be 1% by volume or more. If the fiber mixing rate is less than 1% by volume, the strength and impact resistance may not be sufficient. Preferably, the fiber mixing rate is 5% by volume or more, more preferably 10% by volume or more.

Here, the fiber mixing ratio (Vf: fiber volume fraction) in the present invention is the following formula: Vf = (V1 / V2) × 100 (I)
(In the formula, V1 indicates the volume (liter) of the reinforcing fiber mixed in the unit volume (1 liter) of the fiber-reinforced resin composite containing fibers, and V2 indicates the unit volume (1 liter of the fiber-reinforced resin composite). ) (Volume%).

  Furthermore, various surfactants are attached to the above fibers in order to improve the adhesion between the reinforcing material fibers and the resin, and the oils and scouring agents that are originally attached to the fibers (both are interfaces) Adhesiveness with the resin can also be improved by leaving a trace amount of the compound containing an activator) without thoroughly washing it.

  The resin used for the fiber reinforced resin composite is phenol resin, epoxy resin, polyester resin, polyamide resin, polyimide resin, polyaminoamide resin, PES (polyethersulfone) resin, PEEK (polyetheretherketone) resin, CP Thermosetting resins or thermoplastic resins such as resins (cross-linked polyester amide, cross-linked polyamino amide) are exemplified, and these can be used as one kind or a mixture of one or more kinds.

  The method of making a fiber reinforced resin composite into a molding material is to blend resin, fibers, fillers, additives, etc., heat melt knead using rolls, kneaders, extruders, etc., and then pelletize or crush after cooling Or by adding a resin varnish to the filler and additives, and then impregnating the resin with the filler by stirring using a Henschel mixer, super mixer, etc., then removing the solvent and molding There is a method to make it into a material. The molding material of the fiber reinforced resin composite obtained by the above method is heated and pressurized with a predetermined mold and cured or heated and plasticized, and then cooled and cured, so that excellent strength, impact resistance, In addition, a molded article having wear characteristics is obtained.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.
In addition, various physical-property evaluation in an Example was measured as follows.

(1) Fiber length and fineness Measured according to JIS-L-1015.

(2) Thermal decomposition start temperature of fiber It measured using the thermal-analysis apparatus (Rigaku Corporation TAS-200).

(3) Tensile strength of fiber It measured based on JIS L-1013.

(4) Tensile modulus of fiber Measured based on JIS L-1013.

(5) Raw material kneadability and fiber dispersibility of fiber reinforced resin composite 500 g of powdered phenol resin (manufactured by Sumitomo Bakelite Co., Ltd.) and fiber are mixed into an Eirich mixer (Nippon Eirich Co., Ltd., R-02 type, capacity: 5 L). The kneadability of the raw material obtained by kneading for about 1 minute at a stirring speed of 1000 rpm using is good when there is no entanglement between the fibers and does not hinder the mold filling operation at the time of molding, and the entanglement of the fibers Yes, if it hinders work during molding.

(6) Flexural strength and impact absorbability of fiber reinforced resin composite After filling 170 g of the mixture obtained above into a molding die of length 130 mm × width 130 mm, 110 ° C., 1 ton, 5 using a predetermined press machine Molded in a semi-hot press for 1 minute. Thereafter, the mold was removed from the molding die and further fired at 200 ° C. for 5 hours. The molded product thus obtained was cut into a width of 10 mm, a height of 4 mm, and a length of 80 mm using a diamond cutter to prepare a specimen of a fiber reinforced resin composite.
For the bending strength measurement, the specimen was measured according to ISO 178 three-point bending measurement method. That is, using a tensile compression tester for 10 tons (manufactured by TOYO BALDWIN, UNIVERSAL TESTING INSTRUMENT MODEL UTM 10t), compress the center of the distance between the fulcrums of 64 mm at a speed of 2 mm / min, and obtain the bending strength from the highest point of stress. It was.
Moreover, about the impact absorptivity, the said test body was measured based on the test of JIS-K-7701 Charpy impact strength. That is, using a Charpy impact tester (Toyo Seiki, DG-CB type), place the test piece so that the tip of the 2.0 J pendulum strikes the blade at the center of the test piece, and measure the impact energy. The value of was obtained from the difference between the potential energy before the pendulum was swung down and the energy of the pendulum left after the test piece was destroyed.
A bending strength of 150 N / mm ² or more and an impact absorption energy of 5 kJ / m ² or more were considered good, and a bending strength of 150 N / mm ² or an impact absorption energy of less than 5 kJ / m ² was judged as defective.

(7) Abrasion resistance of fiber reinforced resin composites Tested based on JIS K-7218 “Plastic sliding wear test method”, load 20 kg, peripheral speed 50 mm / min, when the metal used as the rotating body is aluminum The worn weight of the fiber reinforced resin composite and the metal rotating body was measured.
When the wear amount of the fiber reinforced resin composite was 20 g or less and the wear amount of the aluminum rotator was 10 g or less, the wear amount of the fiber reinforced resin composite was 20 g or the wear amount of the aluminum rotator was over 10 g.

[Example 1]
A fiber reinforced resin composite was prepared at the blending ratio shown in Table 1, and aramid fiber (“Technola” manufactured by Teijin Techno Products Limited (density 1.39 g / cm ³ , fiber diameter 45 μm, length 3 mm, tensile strength 3410 MPa) was prepared as the fiber. The tensile modulus of elasticity was 74 GPa, the elongation at break was 4%, and the thermal decomposition temperature was 500 ° C. The raw material kneadability, bending strength, impact absorption, and wear test of the fiber reinforced resin composite were carried out, and the evaluation results are shown in Table 2. Shown in

[Examples 2 to 5, Comparative Examples 1 to 8]
In Example 1, the blending ratio, fiber type, fiber volume mixing ratio, fiber diameter, fiber length, tensile strength, tensile elastic modulus, elongation at break and thermal decomposition temperature of the fiber reinforced resin composite were changed as shown in Table 1. Then, the fiber reinforced resin composite was prepared, and the raw material kneadability, bending strength, impact absorbability, and wear test of the fiber reinforced resin composite were carried out, and the evaluation results are shown in Table 2.
In the fiber reinforced resin composite of the present invention, the fibers are uniformly dispersed without impairing the good kneadability of the raw materials and workability during molding. In addition, the obtained specimen does not cause rapid fiber breakage even when the applied stress increases, the bending stress does not decrease, and has excellent durability compared to a resin composite not reinforced with the fiber, Impact resistance and wear resistance were recognized. In the three-point bending test, it is clear that the bending stress is 150 N / mm ² and the impact absorption energy is 5 kJ / m ² or more.

  The fiber reinforced resin composite of the present invention has light weight, high heat resistance, high strength, and high impact resistance, and is useful as a structural member for automobiles and electrical parts.

Claims (2)

A fiber reinforced resin composite comprising fibers satisfying the following requirements.
a) The single yarn fiber diameter is 20 to 100 μm, and the fiber length is 0.8 to 15 mm.
b) Tensile strength is 2500 MPa or more, tensile elastic modulus is 50 GPa or more, and elongation at break is in the range of 3 to 8%.
c) The density is 1.5 g / cm ³ or less.
d) The thermal decomposition starting temperature is 300 ° C. or higher.
e) The fiber mixing rate is 1% by volume or more.   The fiber-reinforced resin composite according to claim 1, wherein the fiber is a polyparaphenylene terephthalamide fiber and / or a copolyparaphenylene 3,4'-oxydiphenylene terephthalamide fiber.