JP3036614B2 - High-strength resin-based composite material and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to SMC, BMC, F
The present invention relates to a resin-based composite material formed by FRP molding such as W and RIM, and a method for producing the same.

[0002]

2. Description of the Related Art A resin-based composite material using a glass fiber or a ceramic fiber as a reinforcing fiber base and a polyester resin, an epoxy resin or the like as a matrix resin is known. As a molding technique for forming the resin-based composite material, SMC (Sh
eet Molding Compound), BMC (Bulk Molding Compo)
und), FW (Filament Winding), RIM (Reaction)
Various molding methods such as Injection Molding) and continuous molding methods are known (refer to the revised and supplemented "FRP molding technology", Industrial Research Committee).

[0003] For example, in SMC, a prepreg obtained by impregnating an unsaturated polyester resin or an epoxy resin into a reinforcing fiber base material such as glass fiber is used. It is a resin-based composite. However, in the obtained molded body, the strength of the lamination interface between the prepregs was weak, and the mechanical strength as a whole such as interlayer shear strength and bending strength was insufficient.

In recent years, for the purpose of improving the mechanical strength of the resin-based composite material, there have been proposed methods such as a method using a three-dimensional woven fabric or a stitched preform as a reinforcing fiber substrate, and a method of forming an interlayer reinforcement using whiskers. Has been adopted. According to these means, a resin-based composite material in which the reinforcing fiber base material is three-dimensionally obtained is obtained, so that the interlaminar shear strength and the peel strength are remarkably improved.

[0005]

However, when the above-mentioned means is employed to improve the mechanical strength of the resin-based composite material, there are various problems such as productivity and cost, and it cannot be said that the method is satisfactory. . For example, in a method using a three-dimensional woven fabric, the amount of warp and weft yarns is restricted in order to maintain the shape, and depending on the direction in which the load acts, when a reinforcing fiber base material with a uniform fiber filling amount such as a mat is used. It is considered that the strength is inferior to that of. In addition, there is a problem that productivity is poor and costs are high due to restrictions on weaving technology.

In the method using a stitched preform, warp yarns and weft yarns cannot exist at a portion where a stitch yarn (vertical yarn) exists, and the vicinity of the portion becomes a defect, resulting in concentration of stress and reduction in strength. May be. Furthermore, the interlayer reinforcement molding method using whiskers requires a large amount of pretreatment and molding equipment for orienting the whiskers vertically between the layers, and the amount of whiskers that can be oriented is limited by the filling amount of the reinforcing fibers. There is.

[0007] The present invention has been made in view of such circumstances, and an object of the present invention is to further improve the mechanical strength by a simple method without impairing the characteristics of a reinforcing fiber base material that provides basic strength. And

[0008]

A second aspect of the present invention for solving the above-mentioned problems.
The method for producing a high-strength resin-based composite material according to the invention includes a step of mixing a heating medium that generates heat by high-frequency dielectric heating, a welding medium that is melted by heating of the heating medium, and a matrix resin to form an impregnated resin mixture; A step of impregnating the resin mixture in a liquid state between the reinforcing fiber substrates to form a resin-based composite material, and irradiating the resin-based composite material with high frequency to cause a heating medium to generate heat so that the welding medium is melted; Welding medium
And a step of cross-linking .

In a third aspect of the present invention, there is provided a method for producing a high-strength resin-based composite material, wherein a heating medium which generates heat by high-frequency dielectric heating and a welding medium which is melted by heating of the heating medium are mixed with a reinforcing fiber base material or a reinforcing fiber base. A step of bringing a fiber mixture into contact with a material, a step of impregnating the fiber mixture with a liquid matrix resin to form a resin-based composite material, and a step of irradiating the resin-based composite material with high frequency to generate heat to a heating medium, thereby forming a welding medium. And fusing the adjacent reinforcing fiber substrates with a welding medium to form a crosslink .

In a fourth aspect of the present invention, there is provided a method for producing a high-strength resin-based composite material, comprising mixing a heating medium which generates heat by high-frequency dielectric heating and a welding medium which is melted by heating of the heating medium with a reinforcing fiber base material or a reinforcing fiber base. a step of contacting the wood and fiber mixture, by heating the heating medium is irradiated with high-frequency to the fiber mixture to melt the welding medium, welding the reinforcing fiber substrate to each other adjacent to crosslinked by welding medium fibers And a step of impregnating the welded fibrous body with a liquid matrix resin to form a resin-based composite material.

[0011] The high-strength resin-based composite material of the first invention obtained by the above-mentioned production method comprises a matrix resin
A resin-based composite reinforced fibers by a reinforcing fiber base and a fiber base, the reinforcing fiber base material said solidified after melting
It is characterized by being contained in the matrix resin in a state of being cross-linked to each other by a welding medium separate from the matrix resin . Examples of the heat generating medium that generates heat by high-frequency dielectric heating include carbon powder, carbon fiber, and metal powder. For example, it is preferable to use a needle-like powder obtained by pulverizing carbon fibers, since cross-linking becomes possible even if the reinforcing fiber bases are separated to some extent.

Examples of the welding medium that is melted by the heat generated by the heating medium include glass powder, metal powder, and thermoplastic resin. If metal powder is used, it can also serve as the heating medium, and one type of powder can serve two roles. In addition, if a fusible material such as glass fiber is used as the reinforcing fiber base, the reinforcing fiber base itself can be partially melted by the heating medium, and the reinforcing fiber bases are crosslinked without using a welding medium. Can be done.

In the second and third inventions, the high frequency irradiation
It may be carried out after the matrix resin in the composite material has solidified, but is preferably carried out before the solidification. In this case, if pressure is applied at the same time as irradiation, the welding strength between the reinforcing fiber substrates is further improved. As the matrix resin, either a thermosetting resin or a thermoplastic resin is used, but in the case of the second and third inventions, a resin having high heat resistance is desirable.

The heat-generating medium and the welding medium can be used in the form of powder or the like by mixing and contacting each other. However, if the heat-generating medium is coated with the welding medium and used, the welding medium can be melted more efficiently. To coat the heating medium with the welding medium,
Examples include dipping into a molten welding medium, thermal spraying, CVD or PVD, and sol-gel.

[0015]

According to the manufacturing method of the second and third aspects of the present invention, as shown in FIGS.
, A welding medium 2 and a heating medium 3. Then, the resin-based composite material is irradiated with high frequency. Then, as shown in FIG. 2, the heating medium 3 generates heat by high-frequency dielectric heating, and the heat is transmitted to the welding medium 2 existing near the heating medium 3, and the welding medium 2 is melted. Then, the reinforcing fiber base material 1 adjacent to the vicinity of the welding medium 2 is welded by the molten welding medium 2. In some cases, the reinforcing fiber base 1 itself is melted and the reinforcing fiber bases 1 or the reinforcing fiber base 1 and the heating medium 3 are welded to each other.

Further, in the manufacturing method of the fourth invention, a high frequency is irradiated to the fiber mixture comprising the reinforcing fiber base, the welding medium and the heat generating medium. Weld and bond. Thereafter, a matrix resin is impregnated into a high-strength resin-based composite material. Therefore, in the fourth invention, the matrix resin is prevented from being irradiated with the high frequency, so that the matrix resin is not likely to be degraded by heat and the degree of freedom in selecting the resin material is high. Further, since there is no interposition of the matrix resin, the heat generating medium and the welding medium are more easily brought into contact with each other, and can be efficiently melted.

In the high-strength resin-based composite material thus obtained, since the reinforcing fiber base materials are welded to each other, they are three-dimensionally cross-linked and have high mechanical strength.

[0018]

The present invention will be specifically described below with reference to examples. (Example 1) As shown in FIGS. 3 and 4, a unidirectionally reinforced prepreg 5 in which a 14 μm-diameter glass fiber base material (“T glass” manufactured by Nitto Boseki Co., Ltd.) was impregnated with an epoxy resin was used. Amount of 300 to 400 g / m ² resin content; RC3
(0 to 35 wt%) were prepared, and the glass beads 6 and the carbon powder 7 were laminated on each lamination interface while being sprayed at a weight ratio of 1: 1. The glass beads 6 used had an average particle size of 10 μm, and the carbon powder 7 used was short carbon fibers obtained by pulverizing carbon fibers (“T300” manufactured by Toray Industries, Inc.) in a mortar. The average spraying amount is 1.2 mg in total of the glass beads 6 and the carbon powder 7 per 1 cm ² of the surface area of the prepreg 5.

That is, at the lamination interface of the laminate, the glass fiber substrate 1, the glass beads 6, and the carbon powder 7 are pressed against each other as shown in FIG. 4 to form the fiber mixture according to the present invention. The obtained laminate was heated at 130 ° C. for 2 hours under a pressure of 10 kgf / cm ² , and the epoxy resin was cured to obtain a FRP molded product by the SMC method.

Next, with the FRP molded body immersed in water, microwaves were irradiated for 2 minutes using a household microwave oven. Here, the irradiation in water is performed to prevent oxidation of the matrix resin by blocking the air and increasing the cooling efficiency. About the obtained high-strength resin-based composite material, a three-point bending strength test of t = 3 mm and L / h = 16 was performed a plurality of times, and the flexural modulus and the maximum value of the flexural strength were measured. Then, the fracture surface was observed to determine whether the fracture was interlayer shear fracture or bending fracture. Table 1 shows the results
Shown in (Comparative Example 1) Example 1 except that the prepreg was laminated as it was without spraying glass beads and carbon powder.
In the same manner as in the above, an FRP molded body was obtained by prepreg lamination compression molding. Then, without microwave irradiation, 3
Table 1 shows the results of the point bending strength test. (Comparative Example 2) The same as Example 1 except that microwave irradiation was not performed, and glass beads and carbon powder were interposed at the interface of the laminate. This FRP molded body was also subjected to a three-point bending strength test in the same manner as in Example 1, and the results are shown in Table 1. (Comparative Example 3) An FRP molded body was formed in the same manner as in Comparative Example 1, and was irradiated with microwaves in the same manner as in Example 1. Table 1 shows the results of the three-point bending strength test performed in the same manner as in Example 1.

[0021]

[Table 1] (Evaluation) A comparison between Example 1 and Comparative Example 2 shows that the bending strength is greatly improved depending on the presence or absence of microwave irradiation, and that the fracture modes are interlaminar shear fracture and cohesive fracture, which are fundamentally different. . This means that a cross-link was formed between the prepregs by microwave irradiation.

Further, from the comparison between Example 1 and Comparative Example 3, even when microwaves are irradiated in the absence of glass beads and carbon powder, the bending strength is hardly improved, and the breaking mode is not improved. Furthermore, a comparison between Comparative Example 1 and Comparative Example 2 reveals that merely interposing glass beads and carbon powder slightly improves the bending strength but does not reach that of Example 1, and the bending elastic modulus is lower than that of Example 1. There is no improvement in destruction mode.

That is, by irradiating microwaves in the presence of glass beads and carbon powder, it is clear that crosslinks are formed between the prepregs and the strength is improved. In addition, when the cross section of the high-strength resin-based composite material of Example 1 was observed by SEM, a state in which the glass beads were welded to the glass fiber was observed as shown in FIG. Further, as shown in FIG. 6, a state in which short carbon fibers were welded to a plurality of glass fibers and crosslinked was also observed. That is, the carbon powder generates heat by microwave irradiation,
It is clear that the glass beads and the glass fibers were melted and welded, supporting the estimation based on the results of the three-point bending strength test. Example 2 Glass beads having an average particle size of 10 μm and carbon black having an average particle size of 400 ° were respectively added to an epoxy resin (“Araldite” manufactured by Ciba-Geigy) for 25 minutes.
% By volume to obtain an impregnated resin mixture. Using this impregnated resin mixture, FW molding was performed with 4 ply yarns of a 2200 tex glass fiber base material (“T glass” manufactured by Nitto Boseki Co., Ltd.), and heated at 100 ° C. for 2 hours to obtain an FRP molded body. .

With the FRP molded body immersed in water, microwaves were irradiated for 5 minutes using a household microwave oven. For the obtained high-strength resin-based composite material, the maximum value of the tensile strength in the direction perpendicular to the fiber (90 ° tension) and the maximum value of the tensile strength in the fiber parallel direction (0 ° tension) were measured, and the results are shown in Table 2. . (Comparative Example 4) An FRP molded body by the FW method was obtained in the same manner as in Example 1 except that FW molding was performed using only an epoxy resin without adding glass beads and carbon powder. Table 2 shows the results of the same tensile strength test as in Example 2 without irradiation with microwaves. (Comparative Example 5) The same as Example 2 except that the microwave was not irradiated. This FRP molded body was also subjected to a tensile strength test in the same manner as in Example 2, and the results are shown in Table 2. Comparative Example 6 An FRP molded body was formed in the same manner as in Comparative Example 4, and was irradiated with microwaves in the same manner as in Example 2. Table 2 shows the results of the tensile strength test performed in the same manner as in Example 2.
Shown in

[0025]

[Table 2] (Evaluation) Table 2 shows that although the 0 ° tensile strength is almost the same, the 90 ° tensile strength is remarkably improved only when both powder addition and microwave irradiation are performed. This is a result of an increase in the bonding strength between the fibers, and is an indirect proof that cross-linking has occurred between the reinforcing fiber substrates as in Example 1. (Example 3) Milled fiber of carbon having an average fiber length of 40 µm ("HTA-CM
F-0040-E "(manufactured by Toho Rayon Co., Ltd.) was mixed at 50% by volume, and the mixture was stirred and solidified by cooling. This is crushed and passed through a sieve,
Further, the beads were blown up in a furnace at 850 ° C. to produce beads. Then, sieving was performed again to obtain welded beads having a diameter of 10 μm or less.

Next, 1-2 mg of the above-mentioned welded beads were scattered per 1 cm ² between plain woven glass cloths (manufactured by Nitto Bo Co., Ltd.) having a glass weight of 400 g / m ² , and seven sheets were laminated to form a fiber mixture. . Thereafter, microwaves were irradiated for 1 minute in the air to obtain a welded fibrous body. After that, put the welded fibrous body in a nylon bag, suction it with a vacuum pump from one side and epoxy resin (“Araldite LY556”) from the other side.
Ciba-Geigy Corporation) was injected to impregnate the welded fibrous body with the matrix resin. Then, it was cured with a press at a pressure of 15 kgf / cm and 130 ° C. for 2 hours to obtain an FRP molded body.

The obtained FRP molded article also had the same strength as the other examples, and it was clear that the glass fibers were crosslinked by melting the coated glass layer of the welded beads. In the present embodiment, a milled fiber made of carbon was used. However, for example, "Denka Black" (Denka Corporation)
, 400 °). Further, molten aluminum may be used instead of molten glass.

In this embodiment, the molten glass is coated on the carbon milled fiber. However, glass as a welding medium can be adhered as follows. In other words, for example, continuous filaments of carbon fiber ("T300 6K" manufactured by Toray Industries, Inc.) as a heating medium are arranged, and "Araldite LY556" Ciba-Geigy, Inc.
After spraying an epoxy resin such as made from
Sprinkle with glass beads. Then, by curing the epoxy resin, a carbon fiber coated with glass beads as a welding medium is obtained. If you cut this,
It can be used similarly to the above beads. In this case, the epoxy resin functions as an adhesive.

[0029]

That is, according to the high-strength resin-based composite material of the present invention, the mechanical strength is further improved without impairing the properties of the reinforcing fiber base material which is responsible for the basic strength. Further, even if the fiber base material is partially damaged during use or the like, the fiber base material can be re-adhered only by irradiating high frequency.

According to the production method of the present invention, a high-strength resin-based composite material can be produced extremely easily only by irradiating the resin-based composite material with high frequency, and disadvantages in productivity and cost are reduced. Absent. Further, according to the method of irradiating the fiber mixture with a high-frequency wave to form a welded fibrous body and then impregnating the matrix resin with the matrix resin as in the fourth invention, the high-frequency wave can be irradiated in the air, so that the process can be simplified, At the time of high-frequency irradiation, the matrix resin does not exist, so that there is no deterioration of the matrix resin due to heat.

Further, in the case of molding a thick product, it is assumed that high frequency does not easily reach the inside. However, in this method, high frequency irradiation is performed by first stacking several fiber mixtures, and further performing fiber mixing. It is also possible to form a thick welded fibrous body by repeatedly irradiating several bodies and repeating the irradiation, and impregnating it with a matrix resin to produce a thick molded body.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a configuration in a resin-based composite material according to the present invention.

FIG. 2 is an explanatory view showing a configuration in a resin-based composite material after high-frequency irradiation.

FIG. 3 is an explanatory diagram showing a configuration of a laminated body according to one embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a configuration of a lamination interface of a laminate in one embodiment of the present invention.

FIG. 5 is an SEM photograph showing a structure inside a high-strength resin-based composite material formed in one example of the present invention.

FIG. 6 is an SEM photograph showing a particle structure inside a high-strength resin-based composite material formed in one example of the present invention.

[Explanation of symbols]

1: reinforcing fiber base material 2: welding medium 3: heating medium 4: matrix resin 5: prepreg 6: glass beads (welding medium) 7: carbon powder (heating medium)

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-182309 (JP, A) JP-A-5-269866 (JP, A) JP-A-51-579 (JP, A) JP-A-62-1987 117731 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B29B 11/14 B29C 43/20

Claims (4)

(57) [Claims] 1. A method comprising a matrix resin and a reinforcing fiber base material.
A resin-based composite reinforced fibers by looking reinforcing fiber substrate, the said reinforcing fiber base is solidified after melting Matori'
A high-strength resin-based composite material which is contained in the matrix resin in a state of being cross-linked to each other by a welding medium separate from the matrix resin . 2. A step of mixing a heating medium that generates heat by high-frequency dielectric heating, a welding medium that melts due to the heat generation of the heating medium, and a matrix resin to form an impregnated resin mixture, and strengthening the impregnated resin mixture in a liquid state. A step of impregnating between the fiber base materials to form a resin-based composite material, and irradiating the resin-based composite material with high frequency to cause the heating medium to generate heat so that the welding medium is melted. Cross-linking with said welding medium . A method for producing a high-strength resin-based composite material, comprising: 3. A step of mixing a heating medium that generates heat by high-frequency dielectric heating and a welding medium that is melted by heating of the heating medium with a reinforcing fiber base or contacting the reinforcing fiber base to form a fiber mixture; A step of impregnating the fiber mixture with a liquid matrix resin to form a resin-based composite material; and irradiating the resin-based composite material with a high-frequency wave to generate heat in the heating medium, thereby melting the welding medium, and adjoining the reinforcing fiber. Cross-linking the substrates with each other with the welding medium . A method for producing a high-strength resin-based composite material, comprising: 4. A step of mixing a heating medium that generates heat by high-frequency dielectric heating and a welding medium that is melted by heating of the heating medium with a reinforcing fiber base or contacting the reinforcing fiber base to form a fiber mixture; Irradiating the fiber mixture with high frequency to cause the heat generating medium to generate heat to melt the welding medium, and cross-link the adjacent reinforcing fiber substrates with the welding medium to form a welded fibrous body; A method of impregnating a fibrous body with a liquid matrix resin to form a resin-based composite material.