JP2006305867A - Manufacturing method of fiber reinforced plastic - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of an FRP capable of manufacturing a lightweight FRP having high strength and high rigidity with high productivity. <P>SOLUTION: In the manufacturing method of the FRP, a thermosetting resin which is liquid at a room temperature is formed into a predetermined shape in an uncured state and cooled/solidified to form a thermosetting resin preform, this solidified thermosetting resin preform is arranged in the state laminated on a reinforcing fiber base material to be charged in a mold, the mold is heated/pressurized to melt the thermosetting resin preform to infiltrate the thermosetting resin liquid in the reinforcing fiber base material and the thermosetting resin is subsequently cured. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing a lightweight, high-strength, high-rigidity fiber-reinforced plastic with high accuracy, low cost, and environmental friendliness.

  Fiber reinforced plastic (hereinafter abbreviated as FRP) is lightweight but has excellent mechanical properties such as rigidity, strength, and impact resistance. Therefore, spacecraft members, aircraft members, automobile members, railway vehicle members, ship members, Widely used in many fields such as sports equipment.

  In particular, FRP using a cured thermosetting resin as a matrix resin has many mechanical properties and environmental characteristics better than FRP using a thermoplastic resin as a matrix resin. Is often used as a matrix resin.

  For the production of FRP using a cured thermosetting resin as a matrix resin, a prepreg or SMC (an intermediate made of a high-viscosity, high-viscosity, uncured resin that does not flow in a semi-solid state at room temperature with a reinforcing fiber substrate Sheet molding compounds) are prepared, and these are laminated and heat cured. However, since manufacturing costs for intermediates such as prepregs and SMC sheets are required, the cost of the members is high, and it can be applied to the production of aircraft and high-grade sports components, but is not suitable for mass production of automobiles and the like. Furthermore, since the high-viscosity resin adheres to the reinforcing fiber at room temperature, the reinforcing fiber cannot be sufficiently deformed, and therefore it is very difficult to apply it to a member having a complicated shape.

  For this reason, a preform in which a reinforcing fiber not containing / adhering resin (referred to as a dry base material in the industry) is formed into a predetermined shape is manufactured and placed in a mold, and a low-viscosity liquid heat An RTM (resin transfer molding) method in which a curable resin is injected into a mold and cured by heating to form an FRP member has attracted attention (Patent Document 1). In the RTM method, since a dry base material is used, continuous reinforcing fibers can be shaped into a three-dimensional complicated shape. Since there is no need to cut the continuous fiber as in the prepreg molding, the physical properties of the member are also improved. Furthermore, in the RTM method, a liquid resin at room temperature is heated to about 100 ° C. and injected into the mold, so that the viscosity of the resin is reduced to several hundred centipoises or less, and the resin is impregnated to the inside of the reinforcing fiber. (Wide), lightweight members with few defects such as voids, cavities and unimpregnated can be manufactured. Furthermore, by using a process such as evacuating the inside of the mold, a high-quality structural member with fewer voids and cavities can be manufactured.

  However, since the RTM method requires a resin injection step, the mold is complicated and expensive, and molding auxiliary materials such as tubes and pipes used in the injection step are required. In addition, in addition to the resin that becomes the molded product, a lot of useless resin that remains in the injection path or the like is generated, resulting in a cost increase. Further, in the case of a thermosetting resin, the resin cannot be reused, and cleaning for each batch requires labor, resulting in an increase in cost. There is also a drawback that traces of the injection port and the suction port remain in the molded member. Furthermore, since liquid resin is handled at room temperature, there is a problem that the site is often contaminated with resin leaking from containers and piping.

  On the other hand, a resin film comprising a reinforcing fiber base and an uncured thermosetting resin is placed in a mold, and the reinforcing fiber base is impregnated with a thermosetting resin obtained by melting the resin film by heating, and then cured. An RFI (resin film infusion) method has been newly developed (Patent Document 2). Since a thermosetting resin that is liquid at room temperature is not used like RTM, the site is less likely to get dirty, and it is possible to save time and labor for resin preparation.

However, since the thermosetting resin used in the RFI method is in the form of a film, it is difficult to arrange a predetermined amount in a three-dimensional shape, and it is often used in a shape close to a flat plate. Furthermore, since the resin film is thin and does not stand on its own, it cannot be handled as it is in a three-dimensional shape, and it takes time and effort to place it in a mold. In addition, since the resin is solid at room temperature, the viscosity does not decrease sufficiently even when heated, and the resin impregnation into the reinforcing fiber base becomes insufficient, and a member with few defects such as voids can be obtained like RTM. There is no problem. In order to solve such a problem, a countermeasure (Patent Document 3) has been devised in which the reinforcing fiber base material and the thermosetting resin film are alternately laminated to shorten the resin impregnation distance. There is a problem that the cost increases as a result of taking too much.
Japanese Patent Laid-Open No. 2003-71856 JP 2003-011231 A JP-T-2002-529274

  In view of the problems of the background art, an object of the present invention is to provide an FRP manufacturing method capable of manufacturing a lightweight, high-strength, high-rigidity FRP with high productivity. According to the present invention, since the liquid thermosetting resin having a low viscosity at room temperature is impregnated, a molded product having a complicated shape can be easily formed, and the amount of resin and molding auxiliary material used can be reduced. It is possible to provide a molded body that can be significantly reduced from the conventional ones and has few defects such as voids.

The present invention employs the following means in order to solve such problems. That is,
(1) After forming a thermosetting resin preform by cooling and solidifying a thermosetting resin that is liquid at room temperature into a predetermined shape in an uncured state, the thermosetting resin preform After being placed in a form laminated to the material and loaded into the mold, the mold is heated and pressurized to melt and liquefy the thermosetting resin preform, and the curable fiber base A method for producing a fiber reinforced plastic, comprising impregnating a material and then curing the thermosetting resin.
(2) The method for producing a fiber-reinforced plastic according to (1), wherein the reinforcing fiber substrate is a reinforcing fiber substrate having an unimpregnated part at least in part.
(3) Either of the above (1) or (2), wherein the thermosetting resin preform is obtained by impregnating a carrier with a thermosetting resin liquid, shaping the carrier into a predetermined shape, and cooling and solidifying. The manufacturing method of the fiber reinforced plastic as described in 2.
(4) The method for producing a fiber-reinforced plastic according to any one of (1) to (3), wherein the thermosetting resin preform is covered with a dew condensation prevention material during transportation. .
(5) The method for producing a fiber-reinforced plastic according to any one of (1) to (4), wherein the thermosetting resin is an epoxy resin.
(6) The method for producing a fiber-reinforced plastic according to any one of (1) to (5), wherein the reinforcing fiber substrate includes at least carbon fiber.
(7) The method for producing a fiber-reinforced plastic according to (3), wherein a soft porous sheet is used as a carrier.
(8) A fiber-reinforced plastic manufactured using the method for manufacturing a fiber-reinforced plastic according to any one of (1) to (7).

  ADVANTAGE OF THE INVENTION According to this invention, FRP used suitably for many fields, such as a motor vehicle and sports equipment, can be provided under high productivity.

  The present invention has intensively studied the above-mentioned problem, that is, a method for producing FRP capable of producing a lightweight, high-strength, and high-rigidity FRP with high productivity. A thermosetting resin that is liquid at room temperature is determined in advance. A thermosetting resin preform is formed by cooling and solidifying into a shape of the same, and this cooled and solidified thermosetting resin preform is laminated on the reinforcing fiber base in the mold in the cooled and solidified state. After that, when the mold was heated and pressurized, the resin of the thermosetting resin preform was liquefied and impregnated, and then the thermosetting resin was cured. In addition to being able to solve all at once, it has been clarified that even a complex-shaped FRP can be easily provided with fewer defects such as voids.

  In the present invention, the room temperature is assumed to be a temperature that can normally be taken indoors, and is set to 5 to 40 ° C. That is, being liquid at room temperature means being liquid in the range of 5 to 40 ° C.

  Next, in the present invention, the liquid state means that when a piece of metal having a specific gravity of 7 or more in the same temperature state as the thermosetting resin to be measured is placed on the thermosetting resin and instantaneously buried by gravity, The thermosetting resin is defined as a liquid, and the solidified state is defined as a solidified state in which the thermosetting resin is not immediately buried by the same means. In the present invention, cooling is defined as lowering the temperature below room temperature.

  In addition, the predetermined shape means a shape imitating the product shape of a manufactured product of FRP, or a complicated shape when the product shape is complicated. A thermosetting resin preform that is substantially uncured and is in a predetermined shape after being cooled and solidified is defined as a thermosetting resin preform.

  In addition, that the thermosetting resin is uncured indicates that the curing reaction rate r of the thermosetting resin is 20% or less. However, the curing reaction rate r is the degree of progress of the curing reaction obtained by the following formula from the measured value measured using the calorific value by the differential scanning calorimetry (DSC) measurement.

Reaction rate r (%) = (Hi−Ht) / Hi × 100
Hi: Curing calorific value of the thermosetting resin immediately after mixing the thermosetting resin main component and the curing agent uniformly. Ht: Curing calorific value of the thermosetting resin. The differential scanning calorimetry (DSC) referred to here is a sample. And a thermally inactive reference substance in the same container, put them under equivalent conditions, and increase or decrease the ambient temperature at a constant rate, and the temperature difference between them (differential temperature) ) Is continuously measured, and the amount of absorption and heat generation is calculated from the area surrounded by the temperature difference-time curve from the temperature change of the sample. By using such a method, it is possible to measure the amount of heat generated by curing the thermosetting resin when the reaction is performed under predetermined reaction conditions. As measurement conditions, the rate of temperature rise is 10 ° C./min, and the measurement temperature range is 25 ° C. to 300 ° C.

  Many thermosetting resins that are liquid at room temperature used in the present invention are relatively inexpensive, and if these thermosetting resins can be used, the cost of FRP can be reduced. In addition, thermosetting resins that are liquid at room temperature have a lower viscosity when heated, so they are suitable for impregnation of reinforcing fiber bases, and lightweight members with few defects such as voids, cavities, and unimpregnated are used. Can be manufactured.

  However, in the method of injecting a liquid thermosetting resin into the reinforcing fiber substrate, the thermosetting resin main agent and the curing agent must be mixed immediately before injection, and since it is liquid, it is difficult to handle on site. Furthermore, if the temperature control at the time of mixing is not sufficiently performed, the reaction is accelerated by the self-reaction heat and may be cured.

  Therefore, in the present invention, the thermosetting resin is cured by uniformly mixing the thermosetting resin main agent and the curing agent at a predetermined temperature, and then cooling and solidifying in an uncured state. In addition, it can be easily liquefied in an atmosphere of room temperature or higher, thereby achieving the effect of maintaining the impregnation performance of the reinforcing fiber base material in the same manner as when the RTM method is applied. It has the characteristics in that place.

  In addition, in the RTM method, the injection point into the mold is a point, but the reinforcing fiber base material to be impregnated with the resin is the surface, so it is necessary to devise the position of the injection hole and the position of the suction hole In contrast, in the present invention, since it is arranged in a form that is laminated on the reinforcing fiber base, the entire surface of the thermosetting resin preform is in contact with the reinforcing fiber base, so that the resin can be impregnated with high accuracy. It becomes.

  In the present invention, secondary materials such as tubes and pipes used in the injection process such as the RTM method are not necessary, and a medium for flowing a thermosetting resin far away (secondary material for ensuring a space where the resin can easily flow). In addition, there is an advantage that the amount of secondary materials to be used can be reduced.

  Next, the feature of the present invention is that when the thermosetting resin is cooled and solidified, it is shaped into a predetermined shape to form a thermosetting resin preform. That is, a thermosetting resin preform formed by uniformly shaping a thermosetting resin in which a liquid thermosetting resin main component and a curing agent are uniformly mixed at room temperature into a predetermined shape is cooled and solidified in an uncured state. It is.

  When this thermosetting resin preform is loaded into a mold, it can be positioned by simply laminating and arranging it together with a reinforcing fiber base material, and productivity can be significantly improved. Furthermore, if this thermosetting resin preform is used, the amount of resin to be impregnated into the reinforcing fiber base can be controlled, so that waste of resin can be dramatically reduced compared to the RTM method and the like. Vf (fiber volume content) unevenness and the like can be reduced, and a highly accurate FRP can be manufactured. In addition, since the thermosetting resin itself is liquid at room temperature or higher, it becomes difficult to maintain its shape over time, so it can be quickly loaded into a mold, impregnated, further cured, and made into FRP. Become important.

  In the present invention, when the thermosetting resin preform and the reinforcing fiber base material are laminated and loaded in a mold and the thermosetting resin preform is impregnated into the reinforcing fiber base material, Is characterized in that the resin preform is melted and liquefied by heating and pressurizing and further cured.

  For example, if a thermosetting resin preform is placed on a mold that does not have high thermal conductivity, such as an FRP mold, it becomes liquid at room temperature and can be impregnated. However, if you want to impregnate quickly or accelerate curing, use a metal mold with a heating means to quickly melt the thermosetting resin preform solidified by cooling and increase the resin viscosity. Can be reduced. A metallic mold has a high thermal conductivity, has little temperature unevenness, and can produce a high-quality FRP. Moreover, the impregnation into the reinforcing fiber base is promoted by applying pressure (including pressure reduction in the mold such as bagging).

  Such a thermosetting resin preform of the present invention may be prepared by cooling and solidifying a thermosetting resin that is liquid at room temperature to a temperature below the freezing point. In this case, the resin starts to melt during transportation in a room temperature environment, the rigidity is rapidly lost, and the handling becomes difficult. In addition, some resins containing alcohol and the like are difficult to solidify even at a low temperature below -20 ° C., and the thermosetting resin alone may not maintain rigidity during transportation. Therefore, after mixing a thermosetting resin that is liquid at a predetermined temperature and a curing agent, it is brought into contact with the carrier and cooled and solidified, so that even at a temperature above the freezing point of the thermosetting resin, a certain amount of Rigidity can be maintained, and even when a thermosetting resin preform is placed on the mold, even if the resin on the surface is liquefied, the rigidity is maintained by the combined effect of the solidified resin inside and the carrier. It becomes possible. After the molding is performed and the thermosetting resin is cured, the carrier may be separated from the FRP, or may be integrated as a part of the FRP. In other words, the carrier is defined as one that improves the rigidity as a skeleton of a thermosetting resin preform in order to improve transportability and handling.

  In particular, a soft porous sheet is easy to handle as a carrier. Such a porous sheet may be a non-woven fabric, but is preferably a resin foam, particularly an elastomer resin foam excellent in flexibility, especially polyurethane foam. In the present invention, the term “soft” means that the compressive elastic modulus between strains is 0.1 to 1% and is 10 MPa or less. A thermosetting resin preform can be easily obtained by sucking a thermosetting resin that is liquid at room temperature into a soft porous sheet, shaping, and cooling. The thermosetting resin preform thus obtained has excellent transportability, and once loaded into a mold and pressed, the porous sheet is easily deformed, and the molten thermosetting resin is squeezed out, The reinforcing fiber substrate is impregnated.

  Furthermore, when the thermosetting resin preform of the present invention is transported, it is preferably transported while being covered with a dew condensation prevention material. That is, since such a thermosetting resin preform is cooled to room temperature or lower, when left in a room with high humidity, water droplets adhere to the surface. In the case of using a resin having a high affinity for water, for example, a phenol resin, it may not be a problem, but usually the presence of water often causes uncured properties and deterioration of physical properties and quality. Preferably, the molding should be performed in an environment with low humidity, but there are many cases where the molding must be carried out in a high temperature and high humidity environment. It is not easy to manage the humidity of all large workplaces. In particular, by taking out the thermosetting resin preform from the cooling device and providing a material for preventing condensation so that water droplets do not adhere to the thermosetting resin preform due to condensation before being transported to the mold. The FRP can be produced with high accuracy without water droplets coming into contact with the thermosetting resin preform.

  The FRP of the present invention is composed of a thermosetting resin and a reinforced fiber base material. The thermosetting resin is an epoxy resin, and the reinforced fiber base material contains at least carbon fibers. It is preferably composed of a base material.

  That is, among such FRPs, CFRP (carbon fiber reinforced plastic) made of a combination of a reinforced fiber base material containing carbon fibers and an epoxy resin is most desired to have a light weight effect. That is, carbon fiber is excellent in specific strength and specific rigidity, has a good compatibility with a relatively high rigidity epoxy resin, and can produce a high-performance FRP.

  Next, an example of the manufacturing method of FRP of this invention is demonstrated, referring drawings. FIG. 1 is a diagram showing an example of the procedure of the method for producing FRP in the present invention, and the steps continue in the order of A), B), C), D), E), and F).

  The process shown in FIG. 1A) is a process of preparing the thermosetting resin 2 by mixing the thermosetting resin main component 1a that is liquid at a predetermined temperature with the curing agent 1b. It is preferable to mix uniformly before the curing reaction proceeds so much. Further, the thermosetting resin 1a and the curing agent 1b may be defoamed in advance. By not including air in the thermosetting resin 2, the final FRP molded product can be improved in quality. As the thermosetting resin, epoxy resin, unsaturated polyester resin, vinyl ester resin, phenol resin, maleimide resin, cyanate resin and the like are used.

  In the step shown in FIG. 1B), the uncured thermosetting resin 2 prepared in the step shown in FIG. 1A) is shaped. In the figure, the liquid thermosetting resin 2 is poured into the shaping mold 3 and shaping is performed. In addition, the thermosetting resin 2 cooled and solidified below the freezing point is crushed and shaped with a cold press. The thermosetting resin 2 cast into a flat plate shape, cooled and solidified can be slightly softened at room temperature and shaped by a press.

  In this step, the thermosetting resin 2 alone can be used for shaping, but the thermosetting resin 2 and the carrier can be brought into contact with each other for shaping. The support itself has already been shaped, and the thermosetting resin preform can be shaped by soaking the thermosetting resin 2. As the support, a soft porous foam, a film-like material, a mesh-like material, a spherical or fibrous filler and the like are preferable. The flexible porous foam can be shaped by impregnating the liquid thermosetting resin 2. The film-like material and the mesh-like material are arranged in the shaping mold, and by pouring the liquid thermosetting resin 2, they are integrated after cooling and have rigidity. By pouring a spherical or fibrous filler into the shaping mold together with the liquid thermosetting resin 2, it is integrated after cooling and has rigidity. In any case, it is possible to maintain a certain degree of rigidity even at a temperature higher than the freezing point of the thermosetting resin, rather than making the thermosetting resin preform 6 with only the thermosetting resin 2.

  In the step shown in FIG. 1C), the shaping molds put in the step shown in FIG. 1B) are put in the refrigerator. Since it is only necessary to maintain the shape until the uncured thermosetting resin 2 is solidified by cooling, depending on the manufacturing method, it may not be necessary to place the shaping mold in the refrigerator. The temperature of the refrigerator is preferably equal to or lower than the freezing point of the thermosetting resin, but if difficult, the rigidity is improved by using a carrier or the like together.

  When the thermosetting resin preform 6 thus produced preferably has a reaction rate of less than 10%, the usable time of the resin becomes long, and the impregnation property to the reinforcing fiber base during molding is enhanced. Since the thermosetting resin preform 6 normally dislikes moisture, it is preferable to perform molding in a low humidity environment. However, it is not easy to control the humidity in all of the wide workplaces, and molding is performed in a high temperature and high humidity environment. When it is unavoidable, when transporting the thermosetting resin preform 6, it is preferable to provide a material for preventing condensation so that water droplets do not adhere to the thermosetting resin preform due to condensation. . FIG. 2 shows examples of A), B) and C) as materials for preventing condensation.

  The example shown in FIG. 2A) prevents condensation on the sealed thermosetting resin preform 6 by using the shaping mold 3 used in the step of FIG. 1B as a material for preventing condensation. In the example shown in FIG. 2B, the film-like dew condensation prevention material 10 is attached to the surface of the thermosetting resin preform 6. By stripping the film immediately before being placed in the mold, condensation on the thermosetting resin preform 6 is kept to a minimum. In the example shown in FIG. 3C, the thermosetting resin preform 6 is placed in the sealed container-like dew condensation prevention material 11 to block the outside air. At this time, in order to make it difficult for heat to be transmitted to the cooled thermosetting resin preform 6, the contact area of the fixing jig is small, and the sealed container-shaped dew condensation prevention material 11 is made of a material with low heat conduction. It is preferable.

  In the step shown in FIG. 1D), the cooled and solidified thermosetting resin preform 6 and the reinforcing fiber base 7 created in the step shown in FIG.

  As the reinforcing fiber substrate used here, it is possible to use a reinforcing fiber substrate using glass fibers, aramid fibers, carbon fibers, boron fibers, basalt fibers, polyethylene fibers, natural fibers, modified natural fibers, etc. as fibers. The FRP made of such a reinforcing fiber substrate is suitable as a structural FRP.

  As the form of the reinforcing fiber base, there are a fabric and a reinforcing fiber preform formed into a predetermined shape directly from the fiber. The former is a woven, knitted, braided, stitched, non-woven fabric, etc. The latter is a fiber placement that creates a preform by placing a pin on the edge of the shaping mold and drawing it around the pin. JP 2004-218133), P4 (Programmable Powder Preform Process) (Gerald, JH et al., “Owens-”), in which a chopped fiber and a binder are sprayed together on a shaping mold and fixed by heating. Corning P-4 Technology--The Latest on this New Process ", 48. sup.th Annual Conferencing Composites Institute, The Society Of The Plastic. s Industry, Inc., Feb. 8-11, 1993, pp. 1-9.).

  The mold 8 may be a double-sided mold as shown in FIG. 1D) or a single-sided mold as shown in FIG. As such a mold, an FRP mold or the like can be used, but it is preferable to use a metal mold having a heating means and high thermal conductivity. That is, according to such a metal mold, the thermosetting resin preform solidified by cooling can be quickly melted and the viscosity of the resin liquid can be lowered, which is advantageous for impregnation and curing. Further, by reducing the pressure in the mold by pressurization or bagging, it is possible to prevent voids from being mixed into the molded body and unimpregnated, and further, impregnation into the reinforcing fiber base is promoted.

  The positional relationship of the arrangement of the thermosetting resin preform 6 and the reinforcing fiber base 7 in the molding die may be any of up / down / left / right and lamination. Further, the thermosetting resin preform 6 and the reinforcing fiber base 7 may be brought into direct contact, or a peel ply (a release agent is applied for the purpose of separating the carrier contained in the thermosetting resin preform). The woven fabric may be contacted via an auxiliary material such as an auxiliary material that allows the resin to pass through and can be easily peeled off after molding. When the shape of the manufactured product is complicated, the thermosetting resin preform 6 itself has a shape obtained by dividing the shape of the manufactured product into several parts, and they can be distributed in a distributed manner. For example, the shape of the thermosetting resin preform 6 is made slightly smaller than that of the reinforcing fiber base 7, and the resin is sucked from the end of the reinforcing fiber base 7, or the thermosetting resin preform 6 and the reinforcing fiber base 7 are It is possible to employ a technique such as arranging the resin on either the upper or lower side and sucking the resin from the reinforcing fiber base 7 side.

  In the step shown in FIG. 1E), the thermosetting resin preform 6 is dissolved and impregnated into the reinforced fiber base 7 with a liquid, uncured thermosetting resin, and cured. As described above, impregnation and curing are promoted by using means such as heating and pressurization.

  In the step shown in FIG. 1F), the molded product is removed from the mold 8, and the target FRP 9 is manufactured.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not specifically limited to this.

  According to the conventionally known Va-RTM method, an FRP having high mechanical properties can be manufactured with high quality. On the other hand, when the method of the present invention is applied, it is shown that an FRP having high mechanical properties and good quality can be manufactured with high efficiency and, in some cases, with a substantial reduction in auxiliary materials.

  All examples were carried out under the following common conditions.

The target FRP has a hat shape and is achieved by using a single-sided type or a double-sided type. As the reinforcing fiber substrate, a carbon fiber plain fabric BT70-30 (manufactured by Toray Industries, Inc., carbon fiber basis weight 300 g / m ² ) was used. Cut out according to the shape of the target FRP and laminated in the same direction of 4 layers. As the thermosetting resin, TR-C32 (manufactured by Toray Industries, Inc.) which is an epoxy resin composition was used. TR-C32 is a two-pack type epoxy resin composition in which a main agent mainly composed of an epoxy resin and a curing agent are prepared before use. A thermosetting reaction suitably occurs by blending the main agent of TR-C32 and the curing agent at a weight ratio of 100: 32. It is liquid at room temperature and has a viscosity of about 100 poise at 25 ° C., and the viscosity decreases to 100 centipoise or less at 70 ° C., which is the temperature for impregnation and curing.

  A bending strength test piece having a length of 60 mm and a width of 25 mm was cut out from the flat portion of the obtained hat-shaped bottom in parallel with the weave of the reinforcing fiber base. According to the test method specified in ASTM D-790, using a three-point bending test jig (indenter diameter 10 mm, fulcrum diameter 10 mm), the support span is set to 40 mm, and the bending strength is measured at a crosshead speed of 1.0 mm / min. did. In this example, an Instron (R) universal testing machine 4201 type was used as a tester. The number of measurements was n = 5, and the average value was the bending strength. Furthermore, by observing the cross section of the bending strength test piece with an optical microscope, the presence or absence of voids and the state of resin impregnation into the reinforcing fiber substrate were evaluated. The situation where no voids and unimpregnated portions were observed was judged good, the state where minute voids were observed inside the fiber bundle was acceptable, and the state where voids and unimpregnated portions were observed inside the fiber bundle was judged as poor.

Example 1
The main component of TR-C32 is vacuum degassed at 50 ° C. for 30 minutes, and then uniformly mixed so that the curing agent of TR-C32 and air are not mixed at room temperature to prepare an uncured thermosetting resin. did.

  On the other hand, an upper mold and a lower mold of the shaping mold are cut and bent by Trefan (R) (manufactured by Toray Industries, Inc.), which is a plastic film with a thickness of 0.5 mm and is shaped like an FRP manufactured product. It was created. The aforementioned uncured thermosetting resin was poured into the lower mold of the shaping mold thus prepared, and the thickness of the thermosetting resin preform was regulated by the upper mold. The required thickness of the thermosetting resin preform was determined based on the basis weight of the reinforcing fiber substrate, assuming that the target Vf of the FRP to be created was 55%.

  The uncured thermosetting resin thus integrated by the shaping mold was put into a −50 ° C. freezer together with the shaping mold, and cooled and solidified. After solidifying, the thermosetting resin preform 6 consisting only of the shaping mold and the uncured thermosetting resin was separated in a freezer.

  The mold 8 shown in FIG. 4 is a mold and is a fluorine-based mold release agent for separating from the FRP after the periphery of the mold is covered with a sealant (the film and the mold are in close contact with each other and the inside of the mold is sealed) 14. A certain die-free (R) GA-6010 (manufactured by Daikin Industries) was applied to the mold surface. The reinforcing fiber base material 7 was loaded into a mold, and a bleeder (acting as a spacer to serve as a passage for air and resin) 13 made of a thick non-woven fabric was disposed on the end portion. It is connected to a vacuum pump through a tube connected to the bleeder 13 to enable deaeration. The mold 8 is heated in an oven adjusted to 70 ° C., and when the temperature of the mold 8 is stabilized at 70 ° C., the thermosetting resin preform 6 is taken out of the freezer and reinforced fiber base material is used. 7 is loaded in the upper part, completely sealed with the bagging film 12 quickly, the vacuum pump is operated, and the inside of the mold surrounded by the bagging film 12 is deaerated, so that the molded body is pressurized at atmospheric pressure. It was. Immediately, the thermosetting resin preform 6 was dissolved, and the uncured thermosetting resin started to impregnate and cure the reinforcing fiber substrate. After 2 hours, the curing of the thermosetting resin was completed, and the FRP as the molded product was removed from the mold 8.

  The surface quality of the FRP was good, very light, and the bending strength was 650 MPa, which was not as high as that of Comparative Example 1, but showed high physical properties. Moreover, according to cross-sectional observation, the resin-impregnated state was acceptable. Only the amount of resin required for the FRP molded product needs to be prepared as a thermosetting resin preform, the resin can be used without waste, and there is almost no burrs at the end, and trimming is not performed. FRP could be created in the shape.

Example 2
Similar to Example 1, a thermosetting resin preform 6 made only of an uncured thermosetting resin was prepared.

The mold 8 shown in FIG. 5 is a mold, and each is attached to a press machine and is temperature-controlled at 70 ° C. In order to separate from FRP, Die Free (R) GA-6010, which is a fluorine-based release agent, was applied to the surface of the mold 8. The reinforcing fiber base material 7 is loaded into a mold, and the thermosetting resin preform 6 is taken out from the freezer and loaded on the upper part of the reinforcing fiber base material 7, and the mold is quickly moved up and down to pressurize 6 kg / cm ² . Was added. Immediately, the thermosetting resin preform 6 was dissolved, and the uncured thermosetting resin started to impregnate and cure the reinforcing fiber substrate. After 2 hours, curing of the thermosetting resin was completed, the mold was opened, and the FRP as a molded product was removed from the mold.

  The surface quality of the FRP was good, very light, and the bending strength was 624 MPa, which was not as high as that of Comparative Example 1, but showed high physical properties. Moreover, according to cross-sectional observation, the resin-impregnated state was acceptable. Only the amount of resin required for the FRP molded product needs to be prepared as a thermosetting resin preform, the resin can be used without waste, and there is almost no burrs at the end, and trimming is not performed. FRP could be created in the shape. In addition, compared with Example 1, it was possible to further reduce auxiliary materials such as bagging films, bleeders, sealants, and the amount of work was greatly reduced.

Example 3
A thermosetting resin preform 6 made of only an uncured thermosetting resin was prepared in the same manner as in Examples 1 and 2.

The mold 8 shown in FIG. 6 is a mold, and each is attached to a press machine and is temperature-controlled at 70 ° C. In order to separate from FRP, Die Free (R) GA-6010, which is a fluorine-based release agent, was applied to the surface of the mold 8. The reinforcing fiber base material 7 is loaded into a mold, and the thermosetting resin preform 6 is taken out of the freezer from above and loaded onto the upper portion of the reinforcing fiber base material 7, and the reinforcing fiber base material 7 is further loaded thereon. The mold was quickly moved up and down and a pressure of 6 kg / cm ² was applied. Immediately, the thermosetting resin preform 6 was dissolved, and the uncured thermosetting resin started to impregnate and cure the reinforcing fiber substrate 7. After 2 hours, curing of the thermosetting resin was completed, the mold was opened, and the FRP as a molded product was removed from the mold.

  The surface quality of FRP was good, very light, and the bending strength was 608 MPa, which was not as high as that of Comparative Example 1, but showed high physical properties. Moreover, according to cross-sectional observation, the resin-impregnated state was acceptable. Only the amount of resin required for the FRP molded product needs to be prepared as a thermosetting resin preform, the resin can be used without waste, and there is almost no burrs at the end, and trimming is not performed. FRP could be created in the shape. In addition, compared with Example 1, it was possible to further reduce auxiliary materials such as bagging films, bleeders, sealants, and the amount of work was greatly reduced. It was shown that molding is possible even if a reinforcing fiber base and a thermosetting resin preform are laminated.

Example 4
After defoaming the main component of TR-C32 at 50 ° C. for 30 minutes, uniformly mix the TR-C32 curing agent and air so as not to mix at room temperature to prepare an uncured thermosetting resin. did.

  On the other hand, Trefan (R) having a shape resembling a manufactured product of FRP and a 0.5 mm-thick plastic film having good releasability was cut and bent to create an upper mold and a lower mold of the shaping mold. The aforementioned uncured thermosetting resin was poured into the lower mold of the shaping mold thus prepared, and the thickness of the thermosetting resin preform was regulated by the upper mold. The required thickness of the thermosetting resin preform was determined based on the basis weight of the reinforcing fiber substrate, assuming that the target Vf of the FRP to be created was 55%.

  It put into the -20 degreeC freezer, and it was made to cool and solidify. Since -20 ° C is higher than the freezing point of this epoxy resin, it is hard enough to be deformed when pressed by hand, but the rigidity is increased by using the shaping mold as it is. .

The thermosetting resin preform is transported to the molding die 8 shown in FIG. 7 while being integrated by the shaping die, the shaping lower die is removed, and the thermosetting resin leaving the shaping upper die as a carrier is left as it is. The preform 6 was placed on the reinforcing fiber base 7. The mold was quickly moved up and down and a pressure of 6 kg / cm ² was applied. Immediately, the thermosetting resin preform 6 was dissolved, and the uncured thermosetting resin started to impregnate and cure the reinforcing fiber substrate. After 2 hours, curing of the thermosetting resin was completed, the mold was opened, and the FRP as a molded product was removed from the mold. Since the shaping upper mold as the carrier had good releasability, it could be easily removed from the FRP after molding.

  The surface quality of the FRP was good, very light, and the bending strength was 689 MPa, which was as high as that of Comparative Example 1. Moreover, according to cross-sectional observation, the resin impregnation state was good. Only the amount of resin required for the FRP molded product needs to be prepared as a thermosetting resin preform, the resin can be used without waste, and there is almost no burrs at the end, and trimming is not performed. FRP could be created in the shape. In addition, compared with Example 1, it was possible to further reduce auxiliary materials such as bagging films, bleeders, sealants, and the amount of work was greatly reduced. In addition, compared to Examples 1, 2, and 3, since the thermosetting resin preform is surrounded by the shaping mold during transportation, the physical properties are improved without being affected by water droplets, and the shaping mold is a carrier. Therefore, the handling property was improved when the thermosetting resin preform was transported and placed on the mold.

Example 5
After defoaming the main component of TR-C32 at 50 ° C. for 30 minutes, uniformly mix the TR-C32 curing agent and air so as not to mix at room temperature to prepare an uncured thermosetting resin. did.

  On the other hand, Trefan (R) having a shape resembling a manufactured product of FRP and a 0.5 mm-thick plastic film having good releasability was cut and bent to create an upper mold and a lower mold of the shaping mold. The uncured thermosetting resin described above was absorbed in a soft urethane foam material as a carrier, and then set in a shaping mold. In the same manner as in Example 4, it was put in a freezer at −20 ° C. and cooled and solidified.

The thermosetting resin preform was conveyed to the molding die 8 shown in FIG. 8 while being integrated by the shaping die, the shaping upper die and the lower die were removed, and the thermosetting resin preform 6 was taken out. A peel ply 15 is disposed on the reinforcing fiber base 7 in order to separate the FRP from the porous foam used in the post-molding thermosetting resin preform 6, and the thermosetting resin preform 6 is further formed thereon. Loaded. The mold was quickly moved up and down and a pressure of 6 kg / cm ² was applied. Immediately, the thermosetting resin preform 6 was crushed, and the uncured thermosetting resin started to melt, and impregnation and curing were started on the reinforcing fiber substrate. After 2 hours, curing of the thermosetting resin was completed, the mold was opened, and the FRP as a molded product was removed from the mold. Since the shaping upper mold as the carrier had good releasability, it could be easily removed from the FRP after molding.

  The surface quality of the FRP was good, very light, and the bending strength was 705 MPa, which was as high as that of Comparative Example 1. Moreover, according to cross-sectional observation, the resin impregnation state was good. Only the amount of resin required for the FRP molded product needs to be prepared as a thermosetting resin preform, the resin can be used without waste, and there is almost no burrs at the end, and trimming is not performed. FRP could be created in the shape. In addition, compared with Example 1, it was possible to further reduce auxiliary materials such as bagging films, bleeders, sealants, and the amount of work was greatly reduced. In addition, compared with Examples 1, 2, and 3, since the thermosetting resin preform is surrounded by the shaping mold during transportation, the physical properties are improved without being affected by water droplets, and the porous foam is a carrier. Therefore, the rigidity is sufficiently maintained even at a low temperature of about −20 ° C., and the handling property is improved when the thermosetting resin preform is transported and placed on the mold.

Comparative Example 1
FRP was produced by a conventionally known Va-RTM method.

  The mold 8 shown in FIG. 3 is a mold, and after covering the periphery of the mold with a sealant 14, a die-free (R) GA-6010, which is a fluorine-based mold release agent, is separated on the mold surface in order to separate from the FRP. Applied. Next, the reinforcing fiber base material 7 is loaded into a mold, and a medium (resin diffusion medium, which uses a mesh base material in this example) 16 serving as a path for the liquid resin is placed thereon, and after molding, FRP and In order to make the media 16 separable, a peel ply 15 is disposed between the reinforcing fiber substrate 7 and the media 16. A bleeder 13 was provided at the end of the reinforcing fiber base 7. On the bleeder 13, an aluminum C-type channel (a C-shaped cross section aluminum square material for physically securing the passage of air and resin) 17 is arranged. In FIG. 3, the left aluminum C-type channel 17 is directly connected to a vacuum pump. The deaeration tube thus connected was connected, and a resin injection tube was connected to the right aluminum C-type channel 17 and then sealed with a bagging film 12. The mold 8 was placed in an oven adjusted to 70 ° C., and evacuation was performed using the degassing tube on the left side in FIG. In addition, after the above-mentioned TR-C32 main agent is vacuum degassed at 50 ° C. for 30 minutes, the TR-C32 curing agent and the air-curing thermosetting resin are mixed uniformly so as not to mix air. Prepared. After the mold temperature of the mold 8 was stabilized at 70 ° C., uncured thermosetting resin was injected from the resin injection tube on the right side in FIG. The injected resin flowed along the media 16 and impregnated the reinforcing fiber base 7. After 2 hours, the curing of the thermosetting resin was completed, and the FRP as the molded product was removed from the mold 8.

  The surface quality of the FRP was good, very light, and the bending strength was as high as 729 MPa. Moreover, according to cross-sectional observation, the resin impregnation state was good. On the other hand, in the comparative example, the amount of resin remaining in the tube or media used for injection is wasted, and the peel ply 15, media 16, aluminum C-type channel 17 and tube, etc., must be discarded after molding. There wasn't. In addition, excess resin was generated as burrs at the ends of the reinforcing fiber base.

It is a figure which shows an example of the procedure of the manufacturing method of FRP in this invention. In the manufacturing method of FRP of this invention, it is a figure which shows an example of the method of preventing dew condensation during conveyance of a thermosetting resin preform. It is a figure which shows an example of Va-RTM method which is a comparative example of this invention. It is a figure which shows an example of the manufacturing method of FRP in this invention. It is a figure which shows an example of the manufacturing method of FRP in this invention. It is a figure which shows an example of the manufacturing method of FRP in this invention. It is a figure which shows an example of the manufacturing method of FRP in this invention. It is a figure which shows an example of the manufacturing method of FRP in this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1a Thermosetting resin main ingredient 1b Curing agent 2 Thermosetting resin 3 Shaping mold 4 Shaping mold 5 which put the resin into mold 5 Cooler 6 Thermosetting resin preform 7 Reinforced fiber base material 8 Mold 9 Manufactured by the present invention FRP
10 Film-like Condensation Prevention Material 11 Sealed Container-like Condensation Prevention Material 12 Bagging Film 13 Breeder 14 Sealant 15 Peel Ply 16 Media 17 Aluminum C Type Channel

Claims (8)

After forming a thermosetting resin preform by cooling and solidifying the thermosetting resin that is liquid at room temperature into a predetermined shape in an uncured state, the thermosetting resin preform is laminated on the reinforcing fiber substrate. After being placed in a mold and loaded into the mold, the mold is heated and pressurized to melt the thermosetting resin preform and impregnate the reinforced fiber base material with the thermosetting resin. And then curing the thermosetting resin. The method for producing a fiber-reinforced plastic according to claim 1, wherein the reinforcing fiber substrate is a reinforcing fiber substrate having an unimpregnated portion at least partially. 3. The fiber-reinforced plastic according to claim 1, wherein the thermosetting resin preform is obtained by impregnating a carrier with a thermosetting resin liquid, shaping the carrier into a predetermined shape, and cooling and solidifying the preform. Manufacturing method. The method for producing a fiber reinforced plastic according to any one of claims 1 to 3, wherein the thermosetting resin preform is covered with a dew condensation prevention material during transportation. The method for producing a fiber-reinforced plastic according to any one of claims 1 to 4, wherein the thermosetting resin is an epoxy resin. The method for producing a fiber-reinforced plastic according to any one of claims 1 to 5, wherein the reinforcing fiber substrate contains at least carbon fiber. The manufacturing method of the fiber reinforced plastics of Claim 3 which uses a soft porous sheet as a support body. A fiber-reinforced plastic produced using the method for producing a fiber-reinforced plastic according to claim 1.

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