JP2003048223A - Frp manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an FRP manufacturing method capable of obtaining FRP excellent in quality hard to form an unimpregnated part, voids or the like at a low cost in a high yield. SOLUTION: The FRP manufacturing method comprises at least a setting process (A) for arranging a preform comprising at least a reinforcing fiber substrate on the surface of a mold, a hermetically closing process (B) for covering at least the molding part of a mold with a bag material and providing at least a pressure reducing suction port and a resin injection port to hermetically close them, a pressure reducing process (C) for reducing the internal pressure of the molding part from the a pressure reducing suction port, a heating process (D) for heating the molding part inclusive of the mold, an injection process (E) for injecting a resin in the mold from the resin injection port when the temperature Tm of the mold and the temperature Tv of the bag material are together not less than room temperature and the temperature difference ΔT between both temperatures is 10 deg.C or lower to impregnate at least the reinforcing fiber substrate with the resin and a solidifying process (F) for holding the molding part to a predetermined temperature Tpc higher than room temperature inclusive of the mold to solidify the resin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a fiber reinforced plastic (hereinafter referred to as "FRP") having excellent quality with high productivity. More specifically, the present invention relates to a method for producing an FRP, in which unimpregnated portions, voids and the like are less likely to be formed and FRP having excellent quality can be obtained at low cost and with high yield.

[0002]

2. Description of the Related Art FRP, especially carbon fiber reinforced plastics (hereinafter C
FRP) has been mainly used for materials for space / aviation and sports fields. The technical problem in the above field has been mainly to improve the mechanical properties of FRP until now, but the recent problem is to thoroughly reduce the manufacturing cost of FRP. In addition, the field of application in which FRP is used is
Along with widespread use in general transportation equipment (rail cars, automobiles, ships, etc.) and general industries (wind power generation, civil engineering / construction, etc.), further cost reduction of FRP is strongly required.

An autoclave molding method is known as a typical manufacturing method of these FRPs. In such an autoclave molding method, prepregs in which reinforcing fibers are impregnated with a matrix resin in advance are stacked in a molding die and heated and pressed to mold an FRP. The prepreg which is the intermediate base material used here has a very high quality F
Although there is an advantage that RP can be obtained, FRP cannot be obtained with high productivity because not only high cost is required for manufacturing and storing the prepreg, but also large molding equipment is required.

On the other hand, a resin transfer molding method (RTM) is mentioned as a molding method which is excellent in FRP productivity. In such an RTM, reinforcing fibers that are not impregnated with matrix resin (dry) are placed in a complicated mold and the matrix resin is forcibly injected to impregnate the reinforcing fibers with the matrix resin. FR
Mold P.

However, according to the RTM, unimpregnated parts and voids may be generated due to variations in the viscosity of the matrix resin and slight differences in the manufacturing conditions, resulting in a low FRP molding yield and conversely in productivity. There was a problem of lowering. In addition, since the non-impregnated portion and the location where voids are generated are different for each manufacturing condition where there is no slight difference, the quality of the manufactured FRP is also lowered.

[0006]

DISCLOSURE OF THE INVENTION An object of the present invention is to provide an FR which is excellent in quality because it is difficult to form unimpregnated parts and voids.
It is possible to obtain P with low cost and high yield F
It is to provide a manufacturing method of RP.

[0007]

The present invention employs the following means in order to solve the above problems. That is, (1) a method for producing FRP, which comprises at least the following steps (A) to (F).

(A) a setting step of arranging a preform comprising at least a reinforcing fiber base material on a molding surface mold; (B)
A sealing step of covering at least the molding part of the molding die with a bag material and at least providing a decompression suction port and a resin injection port for sealing, (C) a decompression process of decompressing the molding part by suction from the decompression suction port, (D) a molding die (E) When the temperature Tm of the mold and the temperature Tv of the bag material are both room temperature or higher and the temperature difference ΔT is within 10 ° C., the resin is injected from the resin injection port. Injecting at least the reinforcing fiber base material with a resin, and (F) a solidifying step of solidifying (curing or polymerizing) the resin by keeping the molding part including the molding die at a predetermined temperature Tpc higher than room temperature.

(2) The method for producing an FRP as described in (1) above, wherein the preform comprises at least a reinforcing fiber base material and a resin diffusion passage forming member.

(3) The resin diffusion passage forming member is a core material in which a groove for a resin passage is formed, and the core material is left in the FRP even after the solidifying step (F). The manufacturing method of FRP as described in 1).

(4) The resin diffusion passage forming member is a mesh sheet, and the resin diffusion passage forming member of the mesh sheet is peeled off from the FRP after the solidifying step (F). ) Or the method for producing FRP according to (3).

(5) The method for producing an FRP according to any one of (1) to (4) above, wherein the reinforcing fiber base material contains carbon fibers (6) In the heating step of (D) The heating medium is hot air (1)
~ The method for producing an FRP according to any one of (5).

(7) In the injection step (E), the temperature Tm of the mold or the temperature Tv of the bag material is 50 to 50.
Any of the above (1) to (6), wherein the temperature is in the range of 160 ° C., and the predetermined temperature Tpc of the molding portion is in the range of 80 to 180 ° C. in the solidifying step (F). A method for producing an FRP according to item 1.

(8) In the injection step of (E), the resin injected has a resin viscosity ηp of 50 at the lower temperature of the molding die temperature Tm or the bag material temperature Tv.
The difference Δη between the resin viscosity at the temperature Tm of the mold and the resin viscosity at the temperature Tv of the bag material is 200 mPa · s or less, and the difference (η) is within 200 mPa · s. ) Any one of FRP
Manufacturing method.

(9) In the injection step (E), suction is continued from the reduced pressure suction port until the injected resin gels, and any one of the above (1) to (8) is provided. FRP manufacturing method.

(10) The method according to any one of (1) to (9) above, which further comprises at least the following steps (G) and (H) after the solidification step (F). FRP manufacturing method.

(G) Taking out the solidified FRP, (H) keeping the taken out FRP at a predetermined temperature Tac higher than the predetermined temperature Tpc of the molding part and not lower than 100 ° C. to completely remove the resin. Complete solidification process of solidifying (curing or polymerization).

(11) The method for producing an FRP according to any one of (1) to (10) above, which comprises molding an FRP having a maximum length of 3 m or more.

(12) F used as a primary structural member, a secondary structural member, an exterior member, an interior member or their parts in transportation equipment for aircraft, automobiles or ships
(1) to (11), characterized in that RP is molded
The method for producing FRP according to any one of 1.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below in detail based on preferred embodiments.

The method for producing FRP of the present invention comprises at least the following steps (A) to (F). (A) Setting step This is a step of cutting the reinforcing fiber base material into a predetermined size and shape, and arranging a preform, which is laminated as necessary, on the molding die surface.

Here, the preform may be formed on a forming die and arranged as it is, or may be formed by a preform die different from the forming die and transported and arranged on the forming die.

The preform may be fixed and further densified in order to prevent displacement and disorder of each reinforcing fiber base material. As the fixing means, for example,
It is possible to use a means of spraying adhesive particles in a pinpoint manner, in a line shape or entirely, or by arranging adhesive fibers, and then thermally adhering them. Also,
As the densification means, it is possible to use, for example, a press while heating, a means for sucking in a closed space and pressurizing at atmospheric pressure, or the like.

Further, it is preferable that the preform is made of a resin diffusion passage forming member in addition to the reinforcing fiber base material because the resin can be easily impregnated in the injection step (E) described later. Examples of the resin diffusion passage forming member include a core material having a predetermined groove processing, a mesh sheet material having low resin flow resistance, and the like. If the core material is left in the FRP even after molding using such a core material, the sandwich structure F
RP is obtained, and FRP having a skin structure is obtained by peeling and removing after molding using such a mesh sheet. In the latter case, when a release woven fabric (peel ply) is placed between the resin diffusion passage forming member and the reinforcing fiber base material,
It is preferable because the resin diffusion passage forming member can be easily peeled off from the FRP after molding.

It is preferable that such a core material has heat resistance such that the shrinkage rate is 5% or less when a vacuum pressure is applied at 100 ° C. (preferably 120 ° C.). The core material may be either porous or solid, but it is important that the resin does not penetrate from the outer peripheral surface.
In the case of a foam material, it is preferably a closed cell foam. In addition, a material having low hygroscopicity (for example, a swelling ratio after moisture absorption is 5% or less) may be required depending on the application. As a specific material, a foam core made of vinyl chloride (for example, "Kreguesell" (trade name)) or polymethacrylimide (for example, "Rohacell" (trade name)), or a foam core thereof is packed. Examples include honeycomb cores made of aluminum or aramid. In addition, wooden cores and balsa cores are also applicable.

Particularly in the case of manufacturing a sandwich structure FRP, a pressing plate having a relatively high rigidity is provided between the reinforcing fiber base material and the bag material (for example, a resin having a thickness of about 1 to 2 mm reinforced with a glass fiber base material). It is also possible to exhibit smoothness by arranging the plate (made) on the non-mold surface side.
A plurality of pressing plates may be provided and connected while being arranged.

Examples of such reinforcing fiber base material include woven fabrics, knitted fabrics, braids, etc. having two-dimensional unidirectionality, bidirectionality, more multidirectionality, or three-dimensional multidirectionality. A plurality of them may be integrated by stitch threads or knot threads. Particularly when used as a structural member of transportation equipment (particularly aircraft and automobiles), it is preferable to select a unidirectional (or bidirectional, multiaxial) woven fabric.

Examples of the reinforcing fiber include glass fiber, organic (aramid, PBO (paraphenylenebenzobisoxazole), PVA (polyvinyl alcohol), PE (polyethylene), etc.) fiber, carbon fiber (PAN type, pitch type, etc.), etc. Can be used.

Carbon fibers are excellent in specific strength and specific elastic modulus and hardly absorb water, so that they are preferably used as reinforcing fibers for structural materials for aircraft and automobiles. Among them, the following high-toughness carbon fiber yarn has a large impact absorption energy of FRP, and thus can be easily applied as a structural member of an aircraft. That is, the tensile elastic modulus E (GPa) measured according to JIS R7601 is 210 GPa or more and the fracture strain energy W (MJ / m ³ = 10 ⁶ × J / m ³ ) is 40.
It is preferably MJ or more. More preferably, the tensile elastic modulus is more than 240 and less than 400 GPa, and the breaking strain energy is 50 MJ / m ³ or more. Here, the breaking strain energy is calculated by the following equation (W using the tensile strength σ (GPa) measured according to JIS R7601 and the above E value.
= Σ ² / 2E). (B) Sealing Step After the preform and, if necessary, auxiliary materials such as a resin diffusion passage forming member and a release woven cloth are arranged on the molding die surface, for example, a sealing adhesive is applied on the outer periphery of the die surface. Adhesive tape or sealant is adhered, and a bagging film, for example, is disposed as a bag material on the adhesive tape or sealant, and at least the molding portion on the molding die is covered and sealed. Further, in the case of further improving the volume content of the reinforcing fiber base material, in order to exert the effect of preventing the pressure increase in the bag after the resin injection, another bagging film is provided outside the bagging film. It may be covered with or may be left standing for an appropriate time while heating the molding portion while bagging and compressing by utilizing atmospheric pressure. In addition, a reusable rubber sheet made of silicone rubber or the like may be used as the bag material in order to improve economy. In addition, a rubber sheet with a built-in heater may be more effective in heating and heat retention.

Upon sealing, a decompression (vacuum) suction port and a resin injection port are set, and specifically, a line-shaped device having an opening (for example, an aluminum C-type channel material) is reinforced fiber base material. Is arranged around the end portion of, and a resin tube or the like is communicated with the end portion of the line-shaped equipment. (C) Pressure-reducing step The pressure of the molding portion is reduced by suction from the pressure-reducing suction port using, for example, an oil diffusion type vacuum pump. It is preferable to discharge the air that causes voids as much as possible by such decompression, and to press the base material by the atmospheric pressure to increase the reinforcing fiber volume content Vpf of the reinforcing fiber base. The fiber volume content Vpf Is 45% or more, preferably 50
It is preferable to set it to be at least%. In this case, in the heating step (D) described later, if the adhesive particles or the adhesive fibers are heated to a temperature of room temperature or higher at which they can be thermally adhered and kept for a certain period of time, Vpf becomes more stable. Can be higher. (D) Heating Step The molding section including the molding die is heated. In such heating, it is preferable to use hot air as the heating medium. That is, it is preferable to apply hot air that heats the entire mold as a heat source. For example, the method in which the entire molding die is put into a heating oven and hermetically sealed, and the method of circulating hot air in the oven has the highest thermal efficiency and is most preferable. However, a simple room is made of a heat insulating material to cover the entire molding die, A method of blowing hot air with a blower may be used. In any case, when hot air is used as the heating medium, the molding die can be inexpensively and easily placed within a range of ± 5 ° C or less (desirably ± 2 ° C or less) with respect to a predetermined temperature Tm described later. By heating with hot air, higher economic efficiency can be achieved compared to an autoclave. However, when the existing autoclave can be used as it is, an autoclave excellent in terms of temperature unevenness may be used. (E) Injection step The temperature Tm of the mold and the temperature Tv of the bag material are both room temperature or higher, and the temperature difference ΔT between Tm and Tv is 1
When the temperature is within 0 ° C. (more preferably within 8 ° C., further preferably within 5 ° C., particularly preferably within 3 ° C.), the liquid resin contained in a container which has been degassed in advance is preferably used, for example. While continuing the vacuum (vacuum) suction, the tube end communicating with the resin injection port is put into the resin of the container, and the resin is injected into the molding portion of the molding die in which the reinforcing fiber base material is arranged. In some cases, mechanical pressure higher than atmospheric pressure may be loaded to forcefully inject.

When the Tm and Tv are in the range of 50 to 160 ° C., the resin to be described later has a low viscosity, so that not only the impregnation of the resin becomes easier but also the range of selection of the resin itself is widened and the mechanical properties are improved. It is preferable because a high-performance resin having excellent properties can be selected and used.

The ΔT will be described in detail with reference to the drawings. FIG. 1 is a schematic diagram showing the temperature dependence of resin viscosity in an example of resin used in the present invention. When ΔT exceeds 10 ° C., the difference in resin viscosity between the bag material surface and the molding die surface becomes too large, and a remarkable difference in the flow behavior of the resin appears to impair the flow balance, resulting in a preform in the worst case. This causes defects such as unimpregnated parts remaining, and high-quality FRP cannot be stably obtained with high productivity. In particular, when a FRP having a sandwich structure is molded using a core material as a resin diffusion passage forming member, the core material often has a lower thermal conductivity than the reinforced fiber base material, which impedes heat transfer between the molding die and the bag material. Then, the temperature of the reinforcing fiber base material is greatly different, and this phenomenon becomes more remarkable.

The situation of occurrence of ΔT will be described more specifically. For example, when heated with hot air, the reinforcing fiber base material arranged on the bag material side is heated via the bag material, and the reinforcing fiber base material arranged on the molding die side also passes through the molding die. And then heated. However, due to the difference in thickness and material between the mold and the bag material, the heat transfer coefficient and the heat capacity are greatly different, and due to the circulation path of the hot air, when heating is started at the same time, the temperature rises to a predetermined temperature. Unexpectedly large difference occurs in the time to warm. Generally, the bag material has a smaller heat capacity,
The temperature of the reinforcing fiber base material on the bag material side quickly reaches a predetermined temperature, and the above ΔT occurs. Of course, depending on the circulation path of the hot air, the temperature of the reinforcing fiber base material on the molding die side may reach a predetermined temperature quickly.

That is, according to the present invention, there is a relatively large temperature difference between the actual temperature Tm of the mold and the temperature Tv of the bag material due to the difference in the heat transfer path during heating. It was clarified that high quality FRP could not be obtained stably with high productivity, and the problem was solved by the above method.

Here, the Tm may be measured by measuring the temperature in the mold with a thermocouple or the like. In particular, when the mold is a FRP type or a wood type having poor heat conductivity, in the sense of more strictly reflecting the temperature of the reinforcing fiber base material, the measurement point in the molding part is within 5 mm from the surface of the mold, more preferably It is preferable to measure on the surface of the mold.

Further, the temperature Tv of the bag material may be measured by measuring the surface temperature of the bag material in the molding portion with, for example, a thermocouple. Since the bag material is much thinner than the mold, the surface temperature of its outer surface relatively accurately reflects the temperature of the reinforcing fiber substrate even if the heat conduction is poor. Of course, in the sense of more strictly reflecting the temperature of the reinforcing fiber base material, it is preferable to measure the surface temperature of the inner surface of the bag material in the molding part.

The Tm and Tv are measured by
It is preferable that they are opposed to each other in the thickness direction because the flow behavior of the resin can be more accurately predicted. in this case,
Measure at multiple points, and use the Δ
It can be said to be one of the most preferable modes because it can be predicted more accurately within the range of T.

From another point of view, the Tm or T
The resin viscosity ηp at the lower temperature of v is 500 mPa
It is preferable that the difference Δη between the resin viscosity at Tm and the resin viscosity at Tv be within 200 mPa · s. More preferable resin viscosity ηp is 3
50 mPa · s or less, more preferably 200 mPa · s
s or less, more preferable viscosity difference Δη is 150 mPa
· Within s, more preferably within 100 mPa · s. Here, the reason why the above range is preferable is that the above-mentioned temperature difference Δ
It is similar to the case of T. Here, the resin viscosity refers to that measured at the same shear rate using an E-type viscometer (TVE30H manufactured by TOKIMEC).

The resin that has flowed into the cavity flows in the groove processed into the core material in the case of the sandwich structure, particularly in the case of using the resin diffusion passage forming member, and in the resin diffusion passage forming member in the case of the skin structure. It is preferable because the reinforcing fiber base material is impregnated into the reinforcing fiber base material by flowing in the surface direction and diffusing and penetrating into the reinforcing fiber base material in the thickness direction to impregnate the resin efficiently and quickly. When the impregnation of the reinforcing fiber base material is completed, the resin eventually flows out to the vacuum suction port.

According to the production method of the present invention, the resin can be impregnated efficiently and quickly, which is suitable for producing a large FRP having a length of 3 m or more. When molding such a large FRP having a length of 3 m or more, the resin injection speed is lowered below a predetermined level so that the resin does not start gelling before the impregnation of the resin into the whole is completed. Often there are multiple lines. Similarly, there may be a plurality of vacuum suction lines. When a plurality of lines are provided in such a manner, the timing of flowing the resin in each resin injection line is not necessarily constant or simultaneous, and it is preferable to make a judgment while observing the flow state of the resin so that an unimpregnated portion does not occur. If the bag material is transparent or translucent, the flow state of the resin can be easily observed.

It is preferable that the vacuum (vacuum) suction is continued until the injected resin gels, in order to suppress the generation of defects such as unimpregnated portions and voids as much as possible.

As the resin used in the present invention, it is preferable to select a thermosetting resin having a high heat resistance, particularly a resin having a glass transition temperature Tg of 100 ° C. or higher, preferably 150 ° C. or higher by heating. Further, the tensile elongation at room temperature of the resin is preferably 3% or more, more preferably 4.5% or more, from the viewpoint of impact resistance and fatigue characteristics. Examples of such resins include epoxy, phenol (resole type), polybenzimidazole, benzoxazine, cyanate ester, unsaturated polyester, vinyl ester, urea melamine, bismaleimide, polyimide,
It is possible to use polyamide imide and the like, copolymers, modified products thereof and resins prepared by blending two or more kinds thereof, and further resins containing an elastomer or rubber component, a curing agent, a curing accelerator, a catalyst and the like. The thermosetting resin as described above may be divided into a main component and a curing agent, but in that case, it is preferable to degas by vacuum mixing and stirring each of them immediately before injection. When defoaming, heating can be performed to improve the defoaming. (F) Solidification Step It is preferable to stop the resin injection after the impregnation is completed and completely close the resin injection port so that air does not flow into the resin injection port. In that state, the molding part including the molding die is maintained at a predetermined temperature Tpc of room temperature or higher for a predetermined time, and the impregnated resin is solidified (cured or polymerized). Such Tp
When c is in the range of 80 to 180 ° C., solidification of the resin is efficiently promoted and the molding cycle can be shortened, which is preferable.

Here, it is preferable to use hot air as the heating medium. That is, it is preferable to apply hot air that heats the entire mold as a heat source. Here, the reason why hot air is preferable is the same as in the above-mentioned (D) heating step.

In the method for producing FRP of the present invention, the following steps may be carried out after the (F) solidification step, if necessary. (G) Take-out step After the resin is solidified, it is confirmed that the resin has rigidity until it is not deformed at the time of demolding, and the bagging film and the rubber sheet are removed, and the FRP molded body is demolded from the molding die. Take out. The resin diffusion passage forming member, especially the core material, can be left as it is in the molded product, or if necessary,
It is also possible to peel and remove the resin diffusion passage forming member, especially the mesh sheet, from the FRP molded body after molding. In the latter case, if a peel ply (having poor compatibility with the resin to be used, for example, a polyester woven cloth when an epoxy resin is used as the resin) is previously interposed between the reinforcing fiber base material and the reinforcing fiber base material. It can be easily peeled and removed. (H) Complete Solidification Step The FRP molded body taken out is further solidified (cured or polymerized) while being kept at a predetermined temperature Tac higher than the temperature Tpc and not lower than 100 ° C. By this treatment, the resin is completely cured and its glass transition temperature T
Since g can be further increased and FRP can be used for, for example, aircraft members that require heat resistance, it is preferable.

The FRP obtained by the method for producing an FRP of the present invention has not only excellent quality but also high mechanical properties and is lightweight, so that its application is a structure in transportation equipment for aircraft, automobiles and ships. It is preferable that the member is a member, an exterior member, an interior member, or any of these parts. Especially suitable for aircraft structural members,
In addition to secondary structural materials such as various fairings, main landing gear doors, tail cones, engine nacelles, control surfaces, etc., primary structures such as main wings, floor support girders, fuselage, vertical stabilizers, horizontal stabilizers, wing boxes, keels, etc. It is preferable that the material is molded by the FRP manufacturing method of the present invention.

[0046]

EXAMPLE A more specific example will be described below. First, the following examples and comparative examples were carried out on the molding conditions and the configuration specifications of the molding apparatus. (1) Structure: A flat body having a sandwich structure almost entirely, a skin structure having 100 mm of end portions of the entire circumference, a length of about 5 m, and a width of about 3 m (secondary structural member for aircraft, for example, fairing is assumed). (2) Structure of reinforcing fiber base material: (2-1) Sandwich structure plane portion (both upper and lower side surfaces);
"Torayca" bi-directional fabric manufactured by Toray Industries, Inc. (200 g / m ²
X6ply) (2-2) Sandwich structure web portion; Toray Industries, Inc.
"Torayca" bidirectional fabric (200g / m ² × 8pl
y) (2-3) Skin structure part at the peripheral edge; “Torayca” bidirectional woven fabric (300 g / m ² × 10ply) manufactured by Toray Industries, Inc. (3) Core material: Polymethacrylimide foam core (“Rohacell”) "); 15 times foaming x thickness 25 mm A rectangular groove (3 mm x 3 mm, 25 mm pitch) is formed in a zigzag pattern in the width direction on the upper and lower surfaces of the core. (4) Mold: A CFRP mold having a thickness of 10 mm and made of carbon fiber and epoxy resin was used, and the frame was a frame structure made of an angle material.

<Example> A CFRP skin layer having a length of 5 m and a width of 3 m or more.
A flat body having an RP sandwich structure was molded by the following method. (A) After the reinforcing fiber base material is cut into a predetermined size and shape so as to have the above-mentioned structure and laminated, the adhesive particles (previously applied to the reinforcing fiber base material at a position where morphological stability is important) A thermosetting resin and a curing agent were mixed and powdered) to melt by heating, and the laminated reinforcing fiber base materials were fixed to each other in the thickness direction. I prepared two sets of it. As shown in FIG. 2, which shows a transverse cross section perpendicular to the longitudinal direction, one obtained by laminating a reinforcing fiber base material on the surface of such a mold is
The reinforcing fiber base material 11, the core material 12, and the base material 11 were arranged in this order. Then, a glass fiber reinforced plastic pressing plate 21 (thickness: 1.5 mm) was arranged thereon, and then resin injection ports 16a, 16b and a vacuum suction port 17 were formed. (B) After that, the entire molding portion of the molding die 20 is covered with the bag material 23.
Covered with adhesive tape 22a, 22b for sealing
It was sealed with. (C) Then, the molding portion was sucked by the vacuum pump 29 through the vacuum suction tube 27 and the vacuum trap 28 which communicated with the vacuum suction port 17. The inside reached a vacuum degree of about 0.8 kPa. (D) Next, the entire molding die 20 including the gantry 31 was heated by hot air of 150 ° C. blown by the hot air generator 33. The entire periphery of the molding die 20 is covered with a heat insulation box 32 including a heat insulation board having a high heat insulation effect and a supporting frame made of a steel thin tube for supporting the heat insulation board. And the hot air generator 3
In order to effectively use the amount of heat of the hot air generated from 3 and blown into the heat insulation box 32, the hot air emitted from the exhaust port 34 of the heat insulation box 32 passes through a heat insulation exhaust duct (not shown). It is configured to return (circulate hot air) to the hot air generator 33. (E) Then, the thermocouple 14a and the temperature indicator 15a
The temperature Tv of the bag material monitored at
Moreover, the temperature Tm of the mold monitored by the thermocouple 14b and the temperature indicator 15b is 75 ° C. (that is, ΔT is 5
(° C), the epoxy resin 24a prepared in the resin tank was mixed with the main agent and the curing agent, defoamed in advance, and was injected into the resin tank at the atmospheric pressure by opening the valve 26a. . However, the resin 24a was placed at a position higher than the molding die 20 and, more precisely, was injected at a pressure higher than atmospheric pressure. The thermocouple 14b was located 3 mm inside the molding surface of the molding part.

The resin 24a gradually flows from the resin injection port 16a through the groove 13 formed in the core material toward the decompression suction port 17, gradually impregnating the reinforcing fiber base material, and eventually another resin injection port. Resin 16 by the time it reaches 16b
The flow velocity of a dropped considerably. Therefore, next, resin injection port 1
Almost at the same time as closing the valve 26a on the 6a side, the valve 26b was opened to start the injection of the resin 24b from the resin injection port 16b. Then, the resin 24b flowing in from the resin injection port 16b eventually reached the reduced pressure suction tube 28 via the reduced pressure suction port 17. After confirming this, the valve 26b on the resin injection port 16b side was also closed and the resin injection was stopped. (F) After that, from the vacuum suction port 17 to the vacuum pump 29
The temperature Tpc of the mold is about 13 while continuing to reduce the pressure.
The resin with which the reinforcing fiber base material was impregnated was cured by maintaining the hot air temperature for about 3 hours while controlling the hot air temperature so as to maintain 0 ° C. (G) After confirming that the resin has hardened to a demoldable state, remove the secondary materials such as tubes and bag materials, and
The RP molded body was taken out from the molding die.

When the FRP molded product was inspected, pinholes and voids were not found anywhere, demonstrating that extremely good molding was performed.

<Comparative Example> In the above item (e), although the temperature Tv of the bag material reached 80 ° C., the temperature T of the molding die was changed.
When m is 65 ° C. (that is, ΔT is 15 ° C.),
Molding was performed in the same manner as in the example except that the injection of the resin was started in the same manner.

When the FRP molded product was inspected, unimpregnated parts and voids were generated at several places, the quality was poor and it could not be said that molding was performed well.

[0052]

As described above, according to the FRP manufacturing method of the present invention, unimpregnated portions, voids and the like are hardly formed, and FRP having excellent quality can be manufactured at low cost with high yield. Such FRP is used for structural members, exterior members, and the like in transportation equipment such as aircrafts, automobiles, and ships.
It is suitable for interior members or parts thereof.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing the temperature dependence of resin viscosity in an example of resin used in the present invention.

FIG. 2 is a schematic cross-sectional view of a molding apparatus showing a method for manufacturing an FRP according to an embodiment of the present invention.

[Explanation of symbols]

Tm: Mold temperature Tv: Bag material temperature ΔT: Difference between mold temperature and bag temperature ηp: Viscosity of resin at lower temperature of Tm or Tv Δη: Resin viscosity at Tm and resin at Tv Difference from viscosity 11: Reinforcing fiber substrate 12: Core material 13: Grooves 14a, 14b: Thermocouples 15a, 15b: Temperature indicators 16a, 16b: Resin injection port 17: Decompression suction port 20: Mold 21: Press plate 22a, 22b: Adhesive tape for sealing 23: Bag materials 24a, 24b: Liquid resin 25a, 25b: Resin injection tubes 26a, 26b: Valve 27: Vacuum suction tube 28: Vacuum trap 29: Vacuum pump 31: Stand 32 : Heat insulation box 33: Hot air generator 34: Exhaust port

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) B29K 307: 04 B29K 307: 04 F term (reference) 4F204 AA36 AD16 AD23 AK01 AM26 AM28 AR06 EA03 EB01 EB11 EF01 EF05 EF27 EF30 EK09 EK13 EW02 EW06

Claims (12)

[Claims] 1. A method for producing FRP, comprising at least the following steps (A) to (F): (A) A setting step of arranging a preform made of at least a reinforced fiber base material on the surface of the molding die, (B) at least the molding portion of the molding die is covered with a bag material, and at least a reduced pressure suction port and a resin injection port are provided and sealed. Sealing step, (C) depressurizing step of depressurizing the molding part by suction from the depressurizing suction port, (D) heating step of heating the molding part including the molding die, (E) temperature Tm of the molding die and temperature Tv of the bag material And are both room temperature or higher and the temperature difference ΔT is within 10 ° C., a step of injecting a resin from a resin injection port and impregnating at least the reinforcing fiber base with the resin, (F) including a mold Predetermined temperature Tp above room temperature
A solidification step in which the resin is solidified while being held at c. 2. The FRP manufacturing method according to claim 1, wherein the preform comprises at least a reinforcing fiber base material and a resin diffusion passage forming member. 3. The resin diffusion passage forming member is a core material in which a groove for a resin passage is formed, and the core material is left in the FRP even after the solidifying step (F). A method for producing the described FRP. 4. The resin diffusion passage forming member is a mesh sheet, and the resin diffusion passage forming member of the mesh sheet is peeled off from the FRP after the solidifying step (F). The method for producing FRP according to item 3. 5. The method for producing an FRP according to claim 1, wherein the reinforcing fiber base material contains carbon fiber. 6. The method for producing FRP according to claim 1, wherein the heating medium in the heating step (D) is hot air. 7. The temperature Tm of the molding die or the temperature Tv of the bag material is 50 to 160 in the step (E) of injecting.
It is in the range of 0 ° C, and the predetermined temperature Tpc of the forming part is in the range of 80 to 180 ° C in the solidifying step of (F), according to any one of claims 1 to 6. FRP manufacturing method. 8. In the step (E) of injecting, the resin to be injected has a resin viscosity ηp of 500 mP at the lower temperature of the molding die Tm or the bag material temperature Tv.
8. The difference Δη between the resin viscosity at the temperature Tm of the mold and the resin viscosity at the temperature Tv of the bag material is 200 mPa · s or less, which is less than or equal to a · s. A method for producing an FRP according to item 1. 9. The FR according to claim 1, wherein in the step (E), the suction is continued from the reduced pressure suction port until the injected resin gels.
Manufacturing method of P. 10. The method for producing FRP according to claim 1, further comprising at least the following steps (G) and (H) after the solidification step of (F). . (G) Step of taking out the solidified FRP, (H) Keeping the taken-out FRP at a predetermined temperature Tac higher than the predetermined temperature Tpc of the molding part and not less than 100 ° C. to completely solidify the resin Complete solidification process. 11. The FRP according to claim 1, wherein an FRP having a maximum length of 3 m or more is molded.
RP manufacturing method. 12. A FRP used as a primary structural member, a secondary structural member, an exterior member, an interior member, or a component thereof in a transportation device of an aircraft, an automobile, or a ship, is molded. The method for producing FRP according to any one of 1.