JP5186854B2 - Preform manufacturing method - Google Patents

Description

  The present invention relates to a method for manufacturing a preform, and more particularly to a method for manufacturing a three-dimensional (three-dimensional) preform used as a reinforcing material for a fiber-reinforced composite material.

  Examples of the fiber used for the fiber-reinforced composite material include carbon fiber, glass fiber, and polyaramid fiber. The fiber is not a monofilament, but a strand (twisted yarn) in which long fibers are bundled or a tow (untwisted) in which a large number of monofilaments are bundled in an untwisted state is used. When handling tow or strands, the fibers are generally treated with a sizing agent in order to increase the convergence of the fibers or to suppress the fluffing of the strands. Moreover, when using glass fiber for a reinforcing material, in order to improve the adhesiveness of glass fiber and matrix resin, glass fiber is processed with coupling agents, such as a silane type, a titanium type, and a chromium type.

  Conventionally, as a fiber reinforced material used for fiber reinforced resin made of polyamide resin in which matrix resin is reaction injection molded, in order to increase the interfacial bond strength between fiber reinforced material and matrix resin RIM nylon, the surface of fiber reinforced material is cured. There has been proposed a fiber reinforcing material that has been surface-treated by adhering an epoxy resin (see Patent Document 1). In the example of Patent Document 1, a carbon fiber plain weave cloth is used, impregnated with an epoxy resin not containing a curing agent, 1.7% adhered to the surface as a sizing agent, and heat-treated at 300 ° C. for 6 hours to obtain a final epoxy. Carbon fiber plain weave cloth with 0.8% resin adhesion is prepared. Then, 20 layers of carbon fiber plain weave cloth are laminated on the mold and RIM nylon is injected to obtain a fiber reinforced resin.

  In addition, the glass fiber that can sufficiently and reliably improve the adhesion between the glass fiber and the resin to be reinforced, and the glass fiber suitable for the production of the glass fiber reinforced resin composite material having high strength and high elasticity can be obtained. A processing method has been proposed (see Patent Document 2). In this treatment method, when producing a glass fiber reinforced resin composite material containing a glass fiber coated with a sizing agent containing one kind of epoxy resin, acrylic resin, and unsaturated polyester as a film forming agent, and before the production, The glass fiber is heated at a temperature of 100 to 350 ° C.

  Conventionally, a method for producing a fiber-reinforced resin molded article having a good appearance in which a portion where the inorganic fiber reinforcing agent is present on the surface of the molded article is prevented from being browned has been proposed (see Patent Document 3). In the method of Patent Document 3, an inorganic fiber reinforcing material is placed in a cavity of a mold composed of an upper mold and a lower mold, the mold is closed, and then a liquid resin raw material is injected into the cavity and cured to complete the curing. Then, the inorganic fiber reinforcement heat-processed at 250-500 degreeC is used in the manufacturing method of the fiber reinforced resin molded object which opens a shaping | molding die and demolds a molded object.

  When the fiber reinforced composite material is plate-shaped, in the case of manufacturing the fiber reinforced composite material, particularly fiber reinforced resin, the mold is closed with the fibers arranged in the mold or the woven fabric laminated. A liquid matrix resin may be injected and cured. However, if the fiber reinforced composite material is not a simple plate shape, but the shape of the plate material is three-dimensionally folded, or a cylinder or container shape, the three-dimensional shape that directly corresponds to the shape of the product in the mold It is difficult to arrange the fiber structure. Therefore, after manufacturing a three-dimensional shape preform at a location different from the mold, the preform is placed in the mold, and then the mold is closed and a liquid matrix resin is injected.

  When manufacturing a three-dimensional fiber structure having a three-dimensional shape, it takes time and effort to directly arrange the fibers into a plurality of layers so as to obtain a target three-dimensional shape and to bond the layers with a thread in the thickness direction. On the other hand, if a method is adopted in which the fibers are arranged in a plurality of layers in a plate shape and then deformed into a target three-dimensional shape by pressing, the labor is less than in the case where the fibers are directly arranged in the target three-dimensional shape. However, in that case, if not joined with the thread in the thickness direction, the three-dimensional three-dimensional fiber structure is moved and placed in a shape-retaining state in order to place it in the mold for injecting the matrix resin. Is difficult. When the thickness direction yarn is inserted in a plate-like state, if the insertion density of the thickness direction yarn becomes high, it becomes difficult to be deformed into a three-dimensional fiber structure of the desired shape by pressing, and the thickness direction yarn When the insertion density is lowered, it becomes difficult to maintain the shape when handling the three-dimensional fiber structure.

Conventionally, after forming a three-dimensional fiber structure with carbon fibers, the shape is maintained by treating the three-dimensional fiber structure with a treatment agent made of rubber or elastomer mixed with tackifier (tackifier). .
JP-A-9-227694 JP 7-33884 A Japanese Patent Laid-Open No. 5-116171

  In order to maintain the shape of the three-dimensional fiber structure, when the three-dimensional fiber structure is treated with a treating agent containing a tackifier, the strength of the product is reduced if it exists in the final product in the state of the tackfire. It is necessary to let When such a high temperature treatment is performed, it becomes difficult to use glass fibers or organic fibers as the fibers.

  In Patent Document 1 and Patent Document 2, it is disclosed that a surface treatment is performed by attaching a cured epoxy resin to the surface of the fiber reinforcement in order to increase the interfacial adhesion strength between the fiber reinforcement and the matrix resin. No consideration is given to shape retention when a three-dimensional fiber reinforcement is formed. Further, in Patent Document 3, since the sizing agent and binder contained in the inorganic fiber reinforcing material have an unstable component at the mold temperature normally employed in the structural RIM, in order to remove it, 250 to The inorganic fiber reinforcing material is heat-treated at 500 ° C., and no consideration is given to shape retention when a three-dimensional fiber reinforcing material is formed with fibers.

  The present invention has been made in view of the above problems, and its purpose is to use a sizing agent and a coupling agent contained in the fiber to form a three-dimensional fiber structure having a three-dimensional shape. An object of the present invention is to provide a method for producing a preform that can easily secure the retainability.

In order to achieve the above object, the invention according to claim 1 includes a step of forming a three-dimensional fiber structure by arranging fiber bundles surface-treated with a reactive surface treatment agent, and the three-dimensional fiber structure. And heat-treating the surface treatment agent without thermally decomposing it . In the present invention, as the fiber bundle, a strand (twisted yarn) in which long fibers are bundled or a tow (untwisted) in which a large number of monofilaments are bundled in an untwisted state is used. Generally, a sizing agent for bundling fibers is added to these fiber bundles. When a fiber bundle is arranged to form a three-dimensional fiber structure having a shape corresponding to a three-dimensional fiber reinforced composite material product, the fiber bundle surface-treated with a reactive surface treatment agent is used. Some sizing agents are reactive such as epoxy resins and unsaturated polyesters. When a reactive sizing agent is added to the fiber bundle, the fiber is treated with a reactive surface treatment agent such as a sizing agent or a coupling agent in the case of a fiber bundle without a reactive sizing agent. A bundle is used to form a three-dimensional fiber structure. Thereafter, when the three-dimensional fiber structure is heat-treated and the surface treatment agent is reacted and cured, the fiber bundles are bonded to each other through the surface treatment agent, and necessary shape retention can be ensured. Therefore, it is easy to maintain the shape of the three-dimensional fiber structure without increasing the density of the thread in the thickness direction for maintaining the shape of the three-dimensional fiber structure or performing treatment with a shape retention agent including a tack fire. Sex can be secured. The three-dimensional fiber structure here refers to a fiber in which the fibers are not bonded to each other, and if the matrix resin is poured into the mold as it is, there is a risk of misalignment or deformation. is there.

  The invention according to claim 2 is the invention according to claim 1, wherein the surface treatment agent is a sizing agent or a coupling agent. Generally, a sizing agent for bundling fibers is added to a fiber bundle used as a reinforcing material for fiber reinforced resin. Further, when the fiber is glass fiber, a coupling agent is added. In general, some of them remain unreacted. In this invention, since the surface treatment agent is a sizing agent or a coupling agent, it is not necessary to bother to add the surface treatment agent.

According to a third aspect of the invention, in the invention of the first or second aspect, the fiber bundle is made of glass fiber. In this invention, when the glass fiber currently widely used as a fiber reinforcement is used, there exists an effect of Claim 1 or Claim 2.
According to a fourth aspect of the invention, in the invention of the first or second aspect, the fiber bundle is made of carbon fiber.

  According to the present invention, using a sizing agent or a coupling agent contained in a fiber, it is possible to easily ensure the form retainability of a preform composed of a three-dimensional three-dimensional fiber structure.

Hereinafter, an embodiment in which the present invention is embodied in a preform as a fiber reinforcement of a fiber reinforced resin will be described with reference to FIGS.
As shown in FIG. 1, the preform manufacturing method is a continuous fiber arraying step in which fiber bundle layers formed by arraying fiber bundles in one direction are stacked to form a flat laminated fiber group having at least biaxial orientation. S1 and a thickness direction thread insertion step S2 for inserting a thickness direction thread as a binding thread in the thickness direction of the flat laminated fiber group. The preform manufacturing method further includes a pressure deformation step S3 in which the laminated fiber group is subjected to pressure deformation using a pressure unit to form a three-dimensional three-dimensional fiber structure, and the three-dimensional fiber structure is heat-treated. And a heat treatment step S4.

  The fiber bundle is made of glass fiber, and as the fiber bundle, a strand (twisted yarn) in which long fibers are bundled or a tow in which a large number of monofilaments are bundled in an untwisted state is used. The fiber bundle is surface-treated with a reactive surface treatment agent. Since commercially available glass fibers are generally surface-treated with a sizing agent and a coupling agent, commercially available glass fibers can be used as they are. In the case of glass fibers that have not been surface-treated, the surface treatment is performed with a sizing agent and a coupling agent prior to the arrangement of the fiber bundles. As the sizing agent, a sizing agent that is reactively cured by heat treatment, for example, an epoxy resin, an unsaturated polyester resin, or an acrylic resin is used. Examples of coupling agents include silane, titanate, and chromium. The amount added is, for example, 0.1 to several percent.

  In the continuous fiber arranging step, as shown in FIG. 2A, a jig 11 in which pins 11a and 11b as regulating members are arranged at a predetermined pitch is used. The jig 11 is formed in a rectangular frame shape, and the pins 11a and 11b are detachably installed. The continuous fibers 12a are arranged between the pins 11a so as to engage with the pins 11a and be folded back on the jig 11, and a 0 degree fiber layer 13a as a fiber layer having an arrangement angle of 0 ° is formed. Further, the continuous fibers 12b are arranged between the pins 11b so as to engage with the pins 11b and bend back, thereby forming a 90-degree fiber layer 13b as a fiber layer having an arrangement angle of 90 °. A plurality of 0-degree fiber layers 13a and 90-degree fiber layers 13b are alternately laminated to form a laminated fiber group 13 that is biaxially oriented. In FIG. 2A, the arrangement intervals of the continuous fibers 12a and 12b are widely illustrated, but the continuous fibers 12a and 12b are arranged in a state where the adjacent continuous fibers 12a and 12b are in contact with each other.

  After the fiber arranging step, the thickness direction yarn inserting step is performed in a state where the laminated fiber group 13 is held by the jig 11. The insertion of the thickness direction thread 14 is performed, for example, in the same manner as the method disclosed in JP-A-8-218249. More specifically, as shown in FIG. 2B, an insertion needle (not shown) having a hole at the tip and a thread 14 in the thickness direction is inserted in the thickness direction of the laminated fiber group 13 as shown in FIG. The insertion needle advances until the hole in which the thickness direction thread 14 is hooked penetrates the laminated fiber group 13. Thereafter, the insertion needle is slightly retracted. As a result, the thickness direction thread 14 is in a state where a U-shaped loop is formed.

  Next, the stopper thread needle (not shown) stops when it passes through the U-shaped loop and reaches the end of the laminated fiber group 13. At this time, the retaining thread 15 is hooked on the tip of the retaining thread needle. Then, the retaining thread needle is pulled back, and the retaining thread 15 is inserted into the U-shaped loop of the thickness direction thread 14. In this state, the insertion needle is pulled back, the retaining thread 15 is tightened by the thickness direction thread 14, and the laminated fiber group 13 is coupled.

  Next, a pressure deformation process is performed in which the laminated fiber group 13 is subjected to pressure deformation to form a three-dimensional three-dimensional fiber structure. In the pressure deformation process, as shown in FIG. 3, the flat laminated fiber group 13 is gripped by a plurality of clamping devices 16 and 17, and a pressing surface having a predetermined shape is applied in a state where a predetermined range of tension is applied. It is shaped by pressing with a fixed mold 18 and a movable mold 19 as pressurizing means. The movable die 19 is fixed to the tip end of the piston rod 20a of the cylinder 20 provided in a state extending in the vertical direction. The fixed mold 18 is divided into two pieces and is configured to be openable in the horizontal direction.

  The clamp devices 16 and 17 are provided with an air cylinder 21 disposed horizontally and a grip portion 22 provided at the tip of the piston rod 21a. The clamp devices 16 and 17 are configured to be able to pull the laminated fiber group 13 with a predetermined range of tension by the air cylinder 21 in a state where the end portion of the laminated fiber group 13 is held by the holding part 22. As shown in FIG. 3 (b), the movable mold 19 presses the laminated fiber group 13 in cooperation with the fixed mold 18 having the mold surface 18a corresponding to the outer shape of the three-dimensional fiber structure 23 to be formed. The original fiber structure 23 is formed.

  Next, a heat treatment step is performed in which the three-dimensional fiber structure 23 obtained in the pressure deformation step is subjected to heat treatment. The heat treatment is performed in a vacuum oven or a nitrogen atmosphere at a temperature at which the sizing agent and the coupling agent are reactively cured for a predetermined time. By the heat treatment, the sizing agent and the coupling agent attached to the continuous fibers 12a and 12b constituting the three-dimensional fiber structure 23 are reaction-cured, and the fibers are stiffened and the entanglement between the fibers is maintained. Or the fibers are joined to each other via a sizing agent or a coupling agent, so that a preform 24 having a form retaining property is formed.

  The preform 24 is used as a fiber reinforcing material of a fiber reinforced resin molded body. For impregnation of the preform 24 with the matrix resin, for example, a resin transfer molding (RTM) method is employed. In the RTM method, the preform 24 is placed in a resin-impregnated mold (molding mold). And after inject | pouring resin into a shaping die and making it impregnate into the preform 24 and making it harden | cure by heating, a fiber reinforced resin molding is obtained by cooling a shaping die.

  As an example, the heat treatment in the heat treatment step was performed under different conditions. Specifically, two conditions of 250 ° C. for 5 hours and 24 hours and two conditions of 300 ° C. for 5 hours and 24 hours were performed in vacuum. In a nitrogen atmosphere, two conditions of 300 ° C. for 5 hours and 24 hours and one condition of 450 ° C. for 5 hours were performed. As a result, the same form retention was obtained under any heat treatment conditions. In addition, the A4 size thing was formed as the flat laminated fiber group 13. FIG.

According to this embodiment, the following effects can be obtained.
(1) The manufacturing method of the preform 24 includes a step of forming a three-dimensional fiber structure 23 by arranging fiber bundles surface-treated with a reactive surface treatment agent, and a heat treatment of the three-dimensional fiber structure 23 And a step of reacting and curing the surface treatment agent. Therefore, the three-dimensional fiber structure 23 can be easily formed without increasing the density of the thickness direction yarns 14 for maintaining the shape of the three-dimensional fiber structure 23 or performing a treatment with a form retention agent including a tack fire. The form retainability can be ensured.

  (2) The fiber bundle is made of glass fiber. Therefore, compared with the case of using carbon fiber, high-strength / high-elasticity polyaramid fiber, polyparaphenylene benzobisoxazole fiber (PBO fiber), etc., the fiber bundle can be easily obtained and the manufacturing cost can be reduced.

  (3) A sizing agent and a coupling agent are used as the surface treatment agent, and a sizing agent and a coupling agent added by the manufacturer of the fiber bundle are used as they are. Therefore, it is not necessary to bother the fiber bundle with the surface treatment agent before arranging the fiber bundle.

  (4) The step of forming a three-dimensional fiber structure includes a step of laminating fiber bundle layers formed by arranging fiber bundles in one direction to form a flat laminated fiber group 13 having at least biaxial orientation, A pressurizing and deforming step of subjecting the laminated fiber group 13 to pressurization and deformation using a fixed mold 18 and a movable mold 19 as pressurizing means to obtain a desired three-dimensional three-dimensional fiber structure 23. Therefore, compared with the case where the three-dimensional fiber structure 23 is formed by arranging the fiber bundles so as to obtain the desired three-dimensional shape of the three-dimensional fiber structure 23 from the beginning, the three-dimensional fiber structure 23 is formed. It becomes easy.

  (5) The step of forming the flat laminated fiber group 13 includes the step of inserting the thickness direction yarn 14 as a binding yarn into the flat laminated fiber group 13 in the thickness direction. Therefore, the operation of inserting the thickness direction thread 14 into the laminated fiber group 13 constituting the three-dimensional fiber structure 23 is simplified as compared with a case where the operation is performed in a state of being transformed into a three-dimensional structure.

  (6) In the pressure deformation step, the flat laminated fiber group 13 is held by the plurality of clamp devices 16 and 17 and pressed by the movable die 19 having a pressing surface of a predetermined shape in a state where a predetermined range of tension is applied. And form. Therefore, the bending process is easily performed without difficulty.

The embodiment is not limited to the above, and may be embodied as follows, for example.
The heat treatment conditions are not limited to the conditions of the above embodiment, and may be any temperature and time at which the surface treatment agent undergoes reaction hardening without thermal decomposition during the heat treatment.

  ○ The surface treatment agent that is added to the fiber bundle from the beginning is not used as it is, but at least one of a sizing agent and a coupling agent may be added to the fiber bundle. Moreover, in the case of the glass fiber to which only the sizing agent is added, after adding a coupling agent, you may perform a continuous fiber arrangement | sequence process.

  ○ Fibers constituting the fiber bundle are not limited to glass fibers. For example, using other inorganic fibers such as carbon fibers, using high-strength organic fibers such as aramid fibers, ultra-high molecular weight polyethylene fibers and polyparaphenylene benzobisoxazole fibers (PBO fibers), and required physical properties Depending on the case, polyester fiber or the like may be used.

  The laminated fiber group 13 is not limited to the two types of fiber layers 13a and 90 ° fiber layers 13b as the fiber layers composed of continuous fibers arranged in one direction, but the 0 ° fiber layers 13a and 90 ° fibers. In addition to the layer 13b, for example, there may be a configuration in which a fiber layer formed by continuous fibers arranged at an orientation angle of +45 degrees and an orientation angle of -45 degrees exists.

  The flat laminated fiber group 13 is not limited to the case of being composed only of continuous fibers arranged in one direction, but continuous fibers arranged in a plurality of directions such as plain fabrics and twill fabrics are mutually connected. The woven fabric having a configuration bonded to the knitted fabric may be laminated, or the knitted fabric may be laminated.

  The flat laminated fiber group 13 does not hold the 0-degree fiber layer 13a and the 90-degree fiber layer 13b by inserting the thickness direction thread 14, and retains the shape only by the effect of curing the surface treatment agent by heat treatment. You may do it.

  The shape of the preform 24 is not limited to a shape in which a flat plate is bent at a plurality of locations. For example, as shown in FIG. 5, a flat plate is wound in a laver shape, or as shown in FIGS. 6 (a) and 6 (b), a recess is formed in a part of the flat laminated fiber group 13 by drawing press processing. 25 may be formed. The thing of FIG. 5 heats in the state which temporarily fastened with the fiber thread | yarn and hold | maintained the shape. In addition, when resin is poured into a mold while temporarily fixed, misalignment may occur. However, since fibers are bonded by heating, misalignment does not occur.

  ○ Depending on the shape of the preform, instead of deforming the flat laminated fiber group 13 by pressing to obtain the desired three-dimensional shape, the fiber bundles are arranged so that the three-dimensional shape is formed from the beginning, and the laminated fiber group 13 is formed. You may form. When forming a cylindrical preform, the fiber bundles may be arranged by dry filament winding. In this case, when the heat treatment is performed in a state where the cylindrical laminated fiber group 13 is held by the decomposable mandrel, the form retainability is secured. And a cylindrical preform is completed by disassembling and removing a mandrel.

  The matrix resin is not limited to a thermosetting resin and may be a thermoplastic resin. When a thermoplastic resin is used as a matrix resin, a method of injecting an unpolymerized resin liquid into a mold and heat-curing, and a method of injecting a thermoplastic polymer into a mold in a state of being heated and melted to make it solid by cooling There is a way. As the thermosetting resin, for example, an epoxy resin or a vinyl ester resin is used. As the thermoplastic resin, engineering plastics such as polyamide, polycarbonate, pobutylene terephthalate and polyacetal are used.

The following technical idea (invention) can be understood from the embodiment.
(1) Before Symbol fiber bundle is made of glass fibers, both sizing agent and coupling agent as the surface treatment agent is used.

(2) Before Symbol forming a three-dimensional fiber structure, the step of forming a flat laminated fiber group at least biaxially oriented by laminating the fiber bundle layer formed by arranging the fiber bundle in one direction And a pressurizing and deforming step of pressurizing and deforming the laminated fiber group using a pressurizing unit to form the three-dimensional fiber structure.

(3) before Symbol forming a flat laminated fiber group comprises a step of inserting binding threads in the thickness direction of the plate-shaped laminated fiber group.

(4) with gripping by a plurality of clamping devices of the tabular laminated fiber group before asked pressure deformable step, in a state of tension in a predetermined range, in the movable mold and the stationary mold having a pressing surface of a predetermined shape Press to shape.

The flowchart which shows the manufacture procedure of preform. (A) is a schematic plan view which shows the arrangement | sequence state of a jig | tool and a continuous fiber, (b) is a schematic cross section which shows the relationship between a laminated fiber group and a thickness direction thread | yarn. (A), (b) is a schematic diagram which shows the state of a pressurization deformation process. The model perspective view of preform. The model perspective view which shows the shape of the preform in another embodiment (A), (b) is a model perspective view which shows the pressurization deformation process of the preform in another embodiment.

Explanation of symbols

  12a, 12b ... Continuous fibers as a fiber bundle, 23 ... Three-dimensional fiber structure, 24 ... Preform.

Claims (4)

A process of forming a three-dimensional fiber structure by arranging fiber bundles surface-treated with a reactive surface treatment agent, and reacting without heat-decomposing the surface treatment agent by heat- treating the three-dimensional fiber structure And a step of curing the preform.   The method for producing a preform according to claim 1, wherein the surface treatment agent is a sizing agent or a coupling agent.   The preform manufacturing method according to claim 1, wherein the fiber bundle is made of glass fiber.   The preform manufacturing method according to claim 1, wherein the fiber bundle is made of carbon fiber.

Images