JP2882638B2 - Molding material - Google Patents

Description

The present invention relates to a prepreg material obtained by laminating and integrating a high-strength, high-modulus film layer and a fiber-reinforced thermosetting resin layer. Excellent mechanical strength such as tension and compression,
The present invention also relates to a thermosetting resin material for molding for producing a molded article having greatly improved impact resistance.

(Prior art and its problems) Conventionally, fiber-reinforced thermosetting resin layers have excellent specific strength and specific elastic modulus, and therefore are required to have high strength, light weight, corrosion resistance, etc., for example, aircraft structural members Alternatively, it is widely used for sports equipment such as racket frames and golf shafts. However, these materials generally have poor toughness, have problems with impact resistance, and furthermore have the drawback that once they undergo an impact fracture, the sharpened fracture surface exposed by the reinforcing fibers is exposed. Therefore, a thermosetting resin that is a matrix resin is modified with a rubber-like polymer,
Alternatively, improvement in toughness has been achieved by modifying the composition by adding a thermoplastic resin or the like, but a satisfactory product has not yet been obtained. Also, U.S. Pat.No. 3,472,730 or
Japanese Patent Application Laid-Open No. 60-63229 and the like have proposed a concept of a prepreg having an interleaf layer. Although it is worthy of attention as a technique for improving impact resistance, the strength and elastic modulus of the interleaf layer are higher than that of the fiber reinforced layer. Is caused by low
Reduction of the mechanical strength such as the tensile strength and bending strength of the molded article is a new problem, and no attention has been paid to the improvement of the broken state. Another problem of the fiber-reinforced thermosetting resin material is a large anisotropy of physical properties. Generally, although the pseudo-isotropy is performed by laminating by changing the orientation direction of the reinforcing fibers, A great deal of labor and effort is required from cutting out prepregs to accurate stacking.

(Problems to be Solved by the Invention) The present invention is a molding which has high mechanical strength such as tensile strength and bending strength, has excellent physical properties other than the fiber orientation direction, and further has high impact resistance. It is an object of the present invention to provide a thermosetting resin material for molding capable of producing a body.

(Means for Solving the Problems) That is, the present invention substantially consists of aramid having a melting point or a decomposition point of 300 ° C. or more, and has a length and width of 35%.
kg / mm ² or more tensile strength and 700 kg / mm ² or more tensile film layer having an elastic modulus and a thermosetting resin material for molding formed by laminating a fiber-reinforced thermosetting resin layer in an uncured, a .

The film used in the present invention needs the following requirements.

First, the film must be substantially composed of aramid, which has no melting point below 300 ° C. If the melting point is less than 300 ° C, it is not preferable because it melts or undergoes thermal deformation during the production process of the composite, such as curing of the resin. It is not preferable because it may decrease. It is necessary to use aramid from the viewpoint of good adhesion to a resin and easy development of high strength and high elastic modulus described below. Aramid includes those having structures represented by the following general formulas (I) and (II), and copolymers thereof.

Or (Wherein R ₁ , R ₂ and R ₃ are And these hydrogen atoms may be substituted with a functional group such as halogen, methyl, ethyl, methoxy, nitro, and nullphone. m and n are average degrees of polymerization and are about 50 to 10
00. The meaning that the film used in the present invention is substantially made of aramid means that components other than aramid may be contained in a small amount as long as the effects of the present invention are not impaired. This means that a small amount of a polymer, an organic low-molecular compound, an inorganic compound, or the like may be contained.

Next, the film used in the present invention needs to have a tensile strength of 35 kg / mm ² or more and a tensile modulus of 700 kg / mm ² or more.

It is clear that the properties of the film used in the present invention are outstanding in comparison with conventional general-purpose films, but the properties of the final molded article are lower than those of the fiber-reinforced thermosetting resin layer. to do as much as possible reduce, these requirements are not must be satisfied, preferably not to have a 45 kg / mm ² or more in tensile strength, or a 100 kg / mm ² or more tensile modulus It is that you are. The film may be a so-called tensilized type in which the tensile strength or tensile modulus is increased in the direction in which tensile strength is required as a composite product, but of course, the film has isotropic performance. The use of is preferred in that the resulting molded article has less directivity in mechanical strength and dimensional stability. In the present invention, the tensile strength and the tensile elastic modulus are arbitrarily selected in two directions orthogonal to each other, for example, the length direction,
That is, the average value in the width direction satisfies the above value.

In the present invention, it is preferable that the film and the thermosetting resin have a sufficient adhesive strength in order to sufficiently exhibit the reinforcing effect. A large adhesive strength is to roughen the surface of the film or tape (invention on film formation, physical or chemical etching after film formation, etc.), to introduce chemically active species to the surface (corona discharge treatment), plasma Treatment, chemical decomposition, etc.), pre-impregnation treatment for adhesion (epoxy compound, isocyanate compound, resorcinol / formalin / latex mixture, etc.), or a combination thereof are preferably used and achieved.

The thickness of the film used in the present invention is appropriately determined in consideration of the lamination structure with the fiber-reinforced thermosetting resin layer in the molded product, but is usually 5 to 100 μm, and preferably 10 to 50 μm.
μm. Depending on the desired properties of the molded article, a laminate of a plurality of film layers and one or more fiber-reinforced thermosetting resin layers may be laminated and used.

The fiber-reinforced thermosetting resin layer referred to in the present invention is a prepreg material obtained by impregnating a reinforcing fiber with a thermosetting resin.

As the reinforcing fibers used in the present invention, glass fibers,
Includes carbon fibers, aramid fibers, polybenzimidazole fibers, polybenzothiazole fibers, or those coated with metal (for example, nickel-plated carbon fibers), and inorganic fibers such as alumina fibers and silicon carbide fibers. In addition, two or more of these fibers can be used in combination.

In addition, the fibers are used in the form of a sheet aligned in one direction or in the form of a woven fabric, and in applications where isotropic mechanical properties are required, the fibers cut to an appropriate length are randomly oriented. It is also used in the form of a mat.

Thermosetting resin used in the present invention is not particularly limited, for example, epoxy resin, phenolic resin,
It is selected from polyimide resin, polyester resin and the like.
In addition, these resins include ultraviolet absorbers, flame retardants, antioxidants, lubricants, colorants, heat stabilizers, antioxidants, reinforcing short fibers, reinforcing powders, molding agents, thermoplastic resins, Elastomers, rubbery substances, and other ordinary resin additives may be added.

The molding material of the present invention can be prepared by various methods.

For example, there is a method in which a B-stage fiber reinforced thermosetting resin, that is, a prepreg and a film are pressed and manufactured. Alternatively, there is a method in which a reinforcing fiber sheet impregnated with a thermosetting resin and a film are press-bonded and then heated to form a B-stage. Alternatively, apply the thermosetting resin in a molten state to the film in advance, or apply it in the form of a solution or mixed solution using an appropriate solvent, and then remove the solvent by heating and press the reinforcing fiber against this. Thereafter, a method of heating can also be used.

On the other hand, with respect to the lamination structure, the film layer and the fiber-reinforced thermosetting resin layer as described above are laminated one by one, or a plurality of layers are further laminated, and a thermosetting resin is applied in advance, and then the B-stage A film layer obtained by laminating two or more formed films and a fiber-reinforced thermosetting resin layer may be pressure-bonded and laminated side-by-side, or the former may be laminated by sandwiching the latter in a sandwich form. In addition, a cylindrical material is manufactured by winding and laminating a fiber-reinforced thermosetting resin layer on a cylindrical mold, and then removing the mold by winding a film layer coated with a thermosetting resin on one surface. It is also possible.

The method of molding a molded article from the molding material of the present invention is not limited at all, and it can be processed into molded articles of various shapes by various methods.

(Example) Next, the present invention will be described in detail using examples.

Reference Example 1 Production of aramid film Logarithmic viscosity (dissolved in 98% concentrated sulfuric acid, C-0.5g / 100ml
(Measured at 30 ° C.), was dissolved 5.5% of poly-p-phenyleneterephthalamide (abbreviated as PPTA) in 99.5% sulfuric acid at a polymer concentration of 12% to obtain a dope having optical anisotropy. The dope is degassed under vacuum, filtered, extruded through a slit die through a gear pump, cast on a tantalum belt polished to a mirror surface, and heated to about 90 ° C. at a relative humidity of about 40%.
The casting dope was optically isotropic through a zone of an air atmosphere, and was introduced together with a belt into a 30% aqueous sulfuric acid solution at 20 ° C. to coagulate. Next, the coagulated film was peeled off from the belt, neutralized with an aqueous solution of sodium hydroxide, and washed with water. Without drying the washed film, stretch it about 1.15 times in the length direction with a roller, then stretch it 1.3 times in the width direction with a tenter, and while maintaining the fixed length, dry at 200 ° C. and further 300 times.
The sample was heat-treated at a constant temperature at ℃.

Under the above conditions, PPTA films of 10 μm and 25 μm were produced.

The resulting film is pale yellow and transparent and has a thermal analysis of 50
No transition temperature was observed below 0 ° C. Table 1 shows the mechanical properties of these films.

Reference Example 2 Production of fiber-reinforced thermosetting resin Epoxy resin (manufactured by Kasei Fiberlight Co., Ltd.^#7714
(Methyl ethyl ketone mixture, solid content 50% by weight)
PAN-based carbon fiber (Asahi Nippon Carbon
High carbon boron made by Ibar 12k) while impregnating this
On a 500mmφ drum around which silicone release paper is wound
I wiped it. Cut this in a direction perpendicular to the fiber direction,
The unidirectional prepreg was prepared by heating at 0 ° C. for 30 minutes. fiber
Had a volume content of 63% and a thickness of about 0.2 mm.

Example 1 A 10 μm-thick PPTA film was pressure-bonded with a carbon fiber unidirectional prepreg and each layer by a hot laminator roll to obtain a molding material.

This is cut out to a size of 150 mm x 150 mm, and 18 layers are laminated so that the fiber direction of the carbon fiber becomes one direction. In an autoclave, it is cured at 140 ° C for 3 hours under a nitrogen pressure of 4 kg / cm ² for 3 hours. A flat plate having a thickness of about 3 mm was obtained.

A 12.7 mm wide and 150 mm long 0 ° bending test piece was cut out from the flat plate, and the bending fracture strength was measured with a universal testing machine AG-10TA manufactured by Shimadzu Corporation.

The broken test piece broke into two pieces, but did not scatter.
Table 2 shows the flexural fracture strength.

Example 2 The carbon fiber prepreg used in Example 1 was 150 mm × 150 mm
25μm PPTA with 10μm thickness coated in advance with ^# 7714 epoxy on both sides, 10 layers laminated so that the fiber direction of carbon fiber is one direction
The film was pressed with a laminator roll for each of the four layers to obtain a sandwich-type molding material.

This was cured and molded under the same conditions as in Example 1 to obtain a flat plate having a thickness of about 2 mm, and a 0 ° bending test piece having a width of 12.7 mm and a length of 100 mm was cut out.

The test piece after bending fracture was bent in a square shape, but did not break. Table 2 shows the flexural fracture strength.

Comparative Example 1 A carbon fiber prepreg was cut into 150 mm × 150 mm, laminated in 19 layers, and autoclaved under the same conditions as in Example 1.
A flat plate was obtained and subjected to a 0 ° bending test.

The test with bending failure completely broke and scattered around. Table 2 shows the flexural fracture strength.

Example 3 A carbon fiber prepreg was wound around a stainless steel cylindrical mold having a diameter of 9 mm by winding a Teflon film so that the fiber axis coincided with the length direction, and then the same epoxy as in Example 2 was used. Four or ten layers of the coated PPTA film were wound, and the mold was removed to obtain two types of cylindrical molding materials.

Wrap a Teflon film around this, push it into a stainless steel tube with an inner diameter of 12 mm, and pressurize it from inside with an airbag (4 kg / cm
² ) While being heated and cured at 140 ° C. for 2 hours, a tube having an inner diameter of about 10 mm and a wall thickness of about 1 mm was obtained.

This was cut out to a length of 65 mm and subjected to an Izod impact test with a weighing weight of 150 kg · cm (hammer weight 3.874 kg, swing angle 135 °). As a result, the energy consumption was as shown in Table 3.

Although the test specimen after the Izod impact test buckles in a square shape and the internal carbon fiber reinforced layer breaks along the fiber axis,
The outer layer did not break, and thus no sharp fracture surface was exposed.

In addition, a part of the molded body was cut out to a length of 15 mm, and compression tests in the longitudinal direction and the radial direction of the tube were performed at a compression speed of 1 mm / min to determine the compressive breaking strength (axial compression strength and surface compression strength). It was measured.

 Table 3 shows the results.

Comparative Example 2 Only the carbon fiber prepreg was placed in the same mold as
The layer and the fiber axis were wound so that they coincided with the length direction, and formed into a molding material under the same conditions as in Example 3 to obtain two types of tubes. Table 3 shows the results of the Izod impact and compression tests.

During the test, these tubes broke apart and scattered along the fiber orientation direction.

Comparative Example 3 Six layers of carbon fiber prepreg only, 45 in the length direction
A cylindrical material was obtained by laminating at a lamination angle of, and molded under the same conditions as in Example 3 to prepare a tube. Table 3 shows the results of the Izod impact and compression tests.

The test broke the tube in two, exposing the sharp fracture surface of the carbon fiber.

(Effect of the Invention) Since the molding material of the present invention is obtained by integrating a reinforcing fiber with a film layer having an extremely large tensile strength and elastic modulus and excellent heat resistance, a molded article molded by this is used. Shows an extremely excellent effect of having excellent mechanical strength and having an unprecedentedly high impact resistance. Further, an isotropic effect of mechanical properties by the angle ply lamination, which requires extremely labor and technology, can be easily achieved, and has great significance in industrial production.

Therefore, the molding material of the present invention can be formed into various shapes by utilizing these characteristics, for example, in the field of sports and leisure such as a golf club shaft and a tennis racket frame, and also in the aerospace field such as a structural member of an aircraft. It is very preferably used.

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Claims (1)

(57) [Claims] 1. An aramid having a melting point or decomposition point of 300 ° C. or more, which is substantially 35 kg / mm ^{2 in} both length and width directions.
A thermosetting resin material for molding formed by laminating a film layer having the above tensile strength and a tensile modulus of 700 kg / mm ² or more and an uncured fiber-reinforced thermosetting resin layer.