JP2021167076A - Manufacturing method for fiber-reinforced resin molded products - Google Patents

Abstract

To provide a method for manufacturing fiber-reinforced resin molded products that can impregnate the fiber layer with resin of high quality while controlling the decrease in productivity.SOLUTION: A method for manufacturing a fiber-reinforced resin molded product that includes the process of impregnating a fiber layer with resin, supplying a first resin composition mixed with a main agent and a hardener to the fiber layer, and supplying a second resin composition mixed with a main agent, a hardener, and a hardening accelerator to the fiber layer when the first resin composition has reached or exceeded the curing start temperature.SELECTED DRAWING: Figure 3

Description

The present disclosure relates to a method for producing a molded product (fiber reinforced resin molded product) reinforced by a fiber layer impregnated with resin.

For example, a high-pressure tank for a fuel cell vehicle has a liner that forms an internal space of the high-pressure tank, and high strength is realized by arranging a fiber layer impregnated with resin on the outer periphery of the liner. ing. Further, not limited to the high-pressure tank for fuel cell vehicles, a fiber layer impregnated with resin may be arranged in order to realize high strength.

Patent Document 1 discloses a method for manufacturing a high-pressure tank, in which a preform provided with a fiber layer on the outer surface of a liner forming an internal space of the high-pressure tank is arranged in a mold, and the mold is provided. It is disclosed that the fiber layer is impregnated with the resin by rotating the preform in the circumferential direction in the mold with the central axis of the preform as the center of rotation while injecting the resin toward the preform arranged inside. Has been done.

Patent Document 2 discloses that a curing accelerator is applied when a fiber (fiber reinforcing member) impregnated with a resin is wound around a liner, and a unit of the fiber reinforcing member is applied according to the thickness of the reinforcing layer. It is described that the amount of the curing accelerator applied per volume is changed.

JP-A-2019-056415 Japanese Unexamined Patent Publication No. 2019-178702

When impregnating the formed fiber layer with resin, it may be difficult to uniformly impregnate the resin depending on the thickness and shape of the layer. On the other hand, if the resin is injected at a high pressure, the material to be molded may be deformed or the equipment may become large-scale due to the pressure. Further, it cannot be said that sufficient impregnation is possible even if the fiber layer is rotated during impregnation.
In particular, the high-pressure tank for a fuel cell vehicle has a thick fiber layer in order to secure strength, and its shape is a cylindrical shape long in the axial direction, so that the above problem is more remarkable.

On the other hand, the above problem may be alleviated by impregnating and curing over time, for example, by adjusting the temperature, but there is a problem that productivity is lowered. Further, if a resin that cures quickly is impregnated with a high pressure for productivity, the viscosity increases at an early stage of resin supply, and the impregnation property deteriorates, which causes quality deterioration.

The present disclosure has been made in view of these circumstances, and when the fiber layer is impregnated with the resin, the production of a fiber-reinforced resin molded product capable of impregnating the fiber layer with high quality while suppressing a decrease in productivity. The main purpose is to provide a method.

The present application is a method for producing a fiber-reinforced resin molded product including a step of impregnating a fiber layer with a resin, wherein the first resin composition in which a main agent and a curing agent are mixed is supplied to the fiber layer, and the first step. Fiber reinforcement including a step of supplying a second resin composition in which a main agent, a curing agent and a curing accelerator are mixed to a fiber layer when one resin composition reaches a curing start temperature or higher. Disclose a method for manufacturing a resin molded product.
Here, the "curing start temperature" means the temperature at which the polymerization reaction starts and a rapid temperature rise occurs.

According to the method for producing a fiber-reinforced resin molded product of the present disclosure, when the fiber layer is impregnated with the resin, high-quality impregnation can be performed while suppressing a decrease in productivity.

FIG. 1A is an exploded view illustrating the mold 20 and the preform 10, and FIG. 1B is a diagram in which the mold 20 and the preform 10 are combined. FIG. 2 is a diagram illustrating the configuration and relationship of the impregnation device 30, the mold 20, and the preform 10. FIG. 3 is a diagram illustrating the flow of the manufacturing method S10 of the fiber reinforced resin molded product. FIG. 4 is a diagram illustrating a step S11 of installation in a mold and deaeration. FIG. 5 is a diagram illustrating a step S12 of starting and stopping the primary supply. FIG. 6 is a graph showing an example of a temperature change of the first resin composition. FIG. 7 is a diagram illustrating the step S13 of changing to the unloading state. FIG. 8 is a diagram illustrating the step S14 of starting the secondary supply. FIG. 9 is a diagram illustrating the step S15 of changing to the tightened state.

[Manufacturing equipment for fiber reinforced plastic molded products]
1 (a) and 1 (b) schematically show a preform 10 to be molded and a mold 20 for impregnating the preform 10 with a resin. In FIGS. 1A and 1B, the mold 20 is represented by a cross section, the preform 10 is represented by a surface rather than a cross section, and the inner morphology is represented by a broken line. It may be expressed in the same way in the following figures.
FIG. 1A is an exploded view of the mold 20 and the preform 10. FIG. 1B is a diagram showing a state in which the preform 10 is installed on the mold 20.
Further, FIG. 2 schematically shows an apparatus for impregnation (impregnation apparatus 30).
As can be seen from the following description, the present disclosure is a so-called RTM (Resin Transfer Molding) in which a fiber layer provided in a preform is impregnated with a resin composition and then cured to form a reinforcing layer. It is related to the fiber reinforced resin molded product.

<Preform>
The preform 10 is an intermediate member that finally becomes a high-pressure tank, which is one aspect of the fiber-reinforced resin molded product, and is configured to have at least a liner 11 and a fiber layer 12. This embodiment is a high-pressure tank for fuel cell vehicles among high-pressure tanks.

The liner 11 is a hollow member that partitions the internal space of the high-pressure tank. The liner may be made of a material that can hold what is contained in the internal space without leaking, and a known material can be used. For example, nylon resin, polyethylene-based synthetic resin, or , It is made of metal such as stainless steel.

The fiber layer 12 is a layer in which fibers are wound around the outer surface of the liner 11 in a number of layers up to a predetermined thickness. The thickness of the fiber layer 12 is determined by the required strength and is not particularly limited, but is set to a thickness of about 10 mm to 30 mm. In particular, in a high-pressure tank for a fuel cell vehicle, it is necessary to form a thick fiber layer in order to secure the strength, which is highly difficult from the viewpoint of impregnating the fiber layer with resin. Of the fiber layers, the liner 11 side of half the thickness may be referred to as the "inner layer side", and the side of the fiber layer opposite to the liner 11 side of half the thickness may be referred to as the "outer layer side". May be described.
Carbon fibers are used as the fibers, and more specifically, they are band-shaped carbon fiber bundles in which carbon fibers are bundled and have a predetermined cross-sectional shape (for example, a rectangular cross section). A fiber layer is formed by wrapping such a carbon fiber bundle around the outer surface of the liner. Further, the fibers (bundles) are wound around the outer surface of the liner 11 by, for example, a filament winding method or the like.

The fiber layer 12 of the preform 10 is impregnated with resin, and if necessary, a protective layer made of glass fiber is further formed on the outer periphery thereof to form a high-pressure tank.

<Type>
The mold 20 is a mold for impregnating the fiber layer 12 of the preform 10 with a resin, and is configured to have an upper mold 21 and a lower mold 22 in this embodiment. By overlapping the upper mold 21 and the lower mold 22, an internal space along the shape of the preform 10 is formed inside the mold 20. This internal space can be evacuated and can form a closed space.

Further, the upper mold 21 can be moved relative to the lower mold 22 as shown by a straight arrow in FIG. 1 (b), whereby the preform 10 can be installed on the mold 20 and from the mold 20. In addition to being able to release (release) the preform 10, it is also possible to move the preform 10 so as to apply pressure, and to remove the applied pressure. More specifically, the mold 20 can be in the open state, the tightened state, and the unloading state as follows.
The open state is a state in which the upper die 21 is completely separated from the lower die 22 and the upper surface of the lower die 22 is exposed and opened (not shown). In this state, the preform 10 is installed on the lower mold 21 and the preform 10 is separated from the mold 20 (released) after impregnation.
The tightened state is a state in which the preform 10 is installed in the mold 20, and the upper mold 21 and the lower mold 22 are completely connected and tightened (see FIGS. 1 (b) and 4). Even in this tightened state, it is preferable that a slight gap is formed between the fiber layer 12 of the preform 10 before impregnation and the surfaces of the upper mold 21 and the lower mold 22. This gap is taken into consideration that the volume of the fiber layer 12 after impregnation becomes larger than the volume before impregnation due to the impregnation of the resin composition. This gap is the same for the upper mold 21 and the preform 10 and the lower mold 22 and the preform 10.
The unloading state is a state in which the preform 10 is installed in the mold 20 and the upper mold 21 and the lower mold 22 are slightly separated from each other in the tightened state (see FIG. 7). The unloading state is achieved, for example, by slightly raising the upper die 21 with respect to the tightened state. At this time, the gap between the upper mold 21 and the preform 10 is larger than the gap between the lower mold 22 and the preform 10. Even in this unloading state, the sealed state is maintained so that the resin composition for impregnation supplied inside does not leak out of the mold 20.

Further, the upper mold 21 is provided with a flow path 21a that reaches from the outside to the fiber layer 12 of the installed preform 10. By flowing the resin composition through the flow path 21a, the resin composition is supplied to the fiber layer 12 and impregnated.
Further, the mold 20 is also provided with an air flow passage for evacuating (vacuum deaeration) in the formed internal space.

Further, the mold 20 is configured so that the temperature can be maintained at a desired temperature by a temperature control device (not shown), and the mold 20 is to grasp the temperature of the installed preform 10. The temperature sensor 23 is arranged so that the temperature sensor 23 can be used.

The material used for the mold 20 is not particularly limited, but as usual, a metal is preferably used, and the mold 20 is a so-called mold.

<Immersion device>
The impregnation device 30 is a device that supplies the resin composition to be impregnated to the mold 20 in which the preform 10 is installed. As can be seen from FIG. 2, the impregnation device 30 of the present embodiment includes a main agent tank 31, a main agent pump 32, a curing agent tank 33, a curing accelerator tank 34, a switching valve 35, a curing agent pump 36, and a mixer 37. have.

The main agent tank 31 is a tank in which the main agent of the composition to be impregnated is stored. The main agent will be described later.
The main agent pump 32 is a pump that supplies the main agent stored in the main agent tank 31 to the mixer 37.
Therefore, the main agent tank 31 and the main agent pump 32 are connected by a pipe, and the main agent pump 32 and the mixer 37 are connected by a pipe.

The curing agent tank 33 is a tank in which the curing agent is stored, and the curing accelerator tank 34 is a tank in which the curing accelerator is stored. The curing agent and curing accelerator will be described later.
The switching valve 35 is connected to the curing accelerator tank 34, and is configured to be able to switch whether or not the curing accelerator is supplied to the mixer 37 by the curing agent pump 36.
Therefore, the curing agent tank 33 and the curing agent pump 36 are connected by piping, the curing accelerator tank 34 and the switching valve 35 are connected by piping, and the switching valve 35 and the curing agent pump 36 are connected by piping. ing. The curing agent pump 36 and the mixer 37 are connected by piping.

The mixer 37 is a device that mixes the supplied main agent and a curing agent (further curing accelerator depending on the process as described later) and sends the resin composition formed by the mixing to the mold 20. Specifically, the mixer 37 is connected to the flow path 21a of the mold 20 (see FIGS. 1 (a) and 1 (b)) by a pipe, and the sent resin composition passes through the pipe to the flow path of the mold 20. Enter 21a. As described above, since the flow path 21a is connected to the fiber layer 12 of the installed preform 10, the resin composition is supplied to the fiber layer 12 and impregnated by flowing the resin composition through the flow path 21a. Can be done.

[Manufacturing method of fiber reinforced plastic molded products]
Next, a method for manufacturing a fiber-reinforced resin molded product will be described. Here, for the sake of clarity, a high-pressure tank is given as a preferable example of the fiber-reinforced resin molded product, and its mold and impregnation device will be described using the mold 20 and the impregnation device 30. However, the present invention is not limited to the use of these molds 20 and the impregnation device 30.

FIG. 3 shows the flow of the fiber-reinforced resin molded product manufacturing method S10 according to one example. As can be seen from FIG. 3, the method S10 for manufacturing the fiber-reinforced resin molded product according to the present embodiment includes a step S11 for installation and deaeration in the mold, a step S12 for starting and stopping the primary supply, and a change to the unloading state. Step S13, a step S14 for starting the secondary supply, a step S15 for changing to the tightening state, a step S16 for stopping the secondary supply, and a step S17 for removing the mold. Hereinafter, each step will be described.

<Step of installation in mold and deaeration S11>
In the step S11 of installation and degassing in the mold (may be referred to as “step S11”), as shown in FIG. 4, the preform 10 is installed in the mold 20 and degassed by vacuuming. .. By this degassing, the impregnated resin composition easily permeates into the fiber layer 12, and the impregnation is performed more smoothly.

More specifically, in this embodiment, the preform 10 is installed on the lower mold 22 in which the mold 20 is opened and the upper surface is largely exposed, and then the lower mold 22 and the preform 10 installed here are installed. The upper mold 21 is arranged so as to cover the surface, and is in a tightened state. Then, the vacuum is degassed by a vacuum pump.
The vacuum degassing is completed before the first resin composition, which is carried out in the next step, is supplied to the fiber layer 12.

<Step S12 of starting and stopping the primary supply>
In the first supply start and stop step S12 (may be referred to as "step S12"), the first resin composition in which the main agent and the curing agent are mixed is supplied to the fiber layer 12, and then the said. Stop supply.

(Main agent)
The main agent is a material capable of strengthening the fiber layer by impregnating the fiber layer 12 and hardening, and an appropriate material can be used as long as it is used. In this embodiment, it is an epoxy resin, but other examples include polyurethane resin, phenol resin, and melamine resin.

(Curing agent and first resin composition)
A curing agent is a material that cures the main agent by mixing with the main agent. The curing agent is mixed with the main agent to form the first resin composition. Therefore, in this embodiment, the curing agent is composed of a material capable of curing the epoxy resin.
The first resin composition is not necessarily limited, but is configured so that it takes a long time to cure and can continue to maintain fluidity until it reaches the layer of the fiber layer 12 in contact with the liner 11. Is preferable. This allows for even faster impregnation. For the first resin composition for that purpose, a temperature higher than the temperature of the mold 20 may be set as the curing start temperature.
Here, the "curing start temperature" means the temperature at which the polymerization reaction starts and a rapid temperature rise occurs.

The type of curing agent is not particularly limited as long as it can be used as the first resin composition satisfying the above, and examples thereof include aromatic polyamines such as dicyandiamide and meta-phenylenediamine. In addition, aliphatic polyamines such as xylene diamine and diethylenetriamine can also be used.

The supply amount of the first resin composition is not particularly limited, but is 50% by mass or more and 67% by mass or less with respect to the total amount of the first resin composition and the second resin composition described later. It is preferable to have. If the supply amount of the first resin composition is less than 50% by mass, the amount of the first resin composition reaching the layer on the liner 11 side of the fiber layer 12 may be small, and the first resin composition If the amount of the substance is more than 67% by mass, it takes a long time to cure the outer layer side required for mold release, which may affect the productivity.

(Supply suspension of the first resin composition)
The supply of the first resin composition is stopped at a temperature at which the first resin composition starts curing, that is, at a temperature at which the polymerization reaction starts and a rapid temperature rise occurs.

(Specific aspect in this embodiment)
Specifically, in this embodiment, as shown in FIG. 5, the main agent stored in the main agent tank 31 is supplied to the mixer 37 by the main agent pump 32. On the other hand, the curing agent stored in the curing agent tank 33 is supplied to the mixer 37 by the curing agent pump 36. At this time, the switching valve 35 is in a state of shutting off the supply of the curing accelerator from the curing accelerator tank 34.
In the mixer 37, the supplied main agent and curing agent are mixed to form the first resin composition, and the mixer 37 supplies the produced first resin composition to the flow path 21a of the mold 20. .. The supplied first resin composition reaches the outer peripheral portion of the fiber layer 12 of the preform 10 installed in the mold 20 and is further impregnated by penetrating into the fiber layer 12.
At this time, if the temperature of the mold 20 is lower than the curing start temperature of the first resin composition, the fiber layer 12 in which the first resin composition is in contact with the liner 11 while maintaining high fluidity. It becomes easier to reach the layer of.

Further, the temperature of the fiber layer 12 is grasped by the temperature sensor 23 provided on the mold 20, and for example, if time is taken on the horizontal axis and temperature is taken on the vertical axis, a graph as shown in FIG. 6 can be obtained. Then, when the temperature is measured by the temperature sensor 23 and reaches a temperature at which it can be determined that the polymerization reaction has started and a rapid temperature rise has occurred as shown by P in FIG. 6, the first step is taken. Stop the supply of the resin composition. However, it is preferable to consider that the supply amount falls within the above range.

As described above, in this step, it is preferable not to lose the fluidity until the first resin composition reaches the innermost layer side of the fiber layer. As a result, even when the fiber layer is thick, the resin is more reliably impregnated up to the inner layer side of the fiber layer. Further, according to this, when the first resin composition is impregnated, a state of high fluidity can be maintained for a long time, so that the supply pressure at the time of impregnation can be suppressed to a low level. It is also possible to reduce the size and cost of the equipment.

<Process of changing to unloading state S13>
In step S13 (sometimes referred to as “step S13”) of changing to the unloading state, the upper die 21 and the lower die 22 are slightly separated from each other after the primary supply is stopped in step S12. The force for pressing the preform 10 is relaxed, and a slight gap is provided between the upper die 21 and the preform 10. The degree of the gap is not particularly limited, but may be about 10% of the thickness of the fiber layer.
In this embodiment, as shown by the straight arrow in FIG. 7, the upper die 21 is raised to change to this unloading state.

<Step S14 for starting secondary supply>
In step S14 (sometimes referred to as “step S14”) of starting the second supply, the second resin composition in which the main agent, the curing agent, and the curing accelerator are mixed is unloaded from the mold 20. Supply to. The remaining supply amount of the second resin composition is determined by the supply amount of the first resin composition.

(Main agent)
The main agent is a material capable of strengthening the fiber layer by impregnating the fiber layer 12 and hardening, and an appropriate material can be used as long as it is used. In this embodiment, it is the same epoxy resin as the main component of the first resin composition. By making the main agent of the first resin composition and the main agent of the second resin composition the same, the difference in physical properties can be reduced, so that problems such as strength and delamination are less likely to occur. Become. However, if there is no problem with such performance, it does not prevent the use of a different base material.

(Hardener)
A curing agent is a material that cures the main agent by mixing with the main agent. Therefore, in this embodiment, the curing agent is composed of a material capable of curing the epoxy resin. In this embodiment, it is the same curing agent as the curing agent of the first resin composition. As a result, the types of required materials can be reduced and the cost can be suppressed.
However, this does not prevent the use of a curing agent different from the curing agent used in the first resin composition. For example, a curing agent that starts curing at a lower temperature than the first resin composition may be used for the second resin composition. According to this, it is possible to cure the outer layer side faster.

(Curing accelerator)
The curing accelerator accelerates the curing of the main agent mixed with the curing agent. By mixing a curing accelerator with a curing agent and supplying it to the main agent, faster curing becomes possible.
The type of the curing accelerator is not particularly limited, and examples thereof include tertiary amines, imidazoles, and phosphorus compounds.

(Specific aspect in this embodiment)
Specifically, in this embodiment, as shown in FIG. 8, the main agent stored in the main agent tank 31 is supplied to the mixer 37 by the main agent pump 32. On the other hand, the curing agent stored in the curing agent tank 33 and the curing accelerator stored in the curing accelerator tank 34 are supplied to the mixer 37 by the curing agent pump 36. At this time, the switching valve 35 opens the flow path by the pipe from the curing agent accelerator tank 34.
In the mixer 37, the supplied main agent, curing agent and curing accelerator are mixed to form a second resin composition, and the mixer 37 transfers the produced second resin composition to the flow path 21a of the mold 20. And supply. The supplied second resin composition reaches the outer peripheral portion of the fiber layer 12 of the preform 10 installed in the mold 20. At this time, the mold 20 is put into the unloading state by the step S13, the pressure on the preform 10 by the mold 20 is suppressed, and a gap is formed between the upper mold 21 and the preform 10. The resistance can be suppressed when the second resin composition flows. Therefore, the supplied second resin composition is smoothly filled between the upper mold 21 and the preform 10.

<Step S15 for changing to the tightened state>
In the step S15 of changing to the tightened state (sometimes referred to as “step S15”), the upper die 21 and the lower die 22 are moved so as to be close to each other, and the die is brought into the tightened state. As a result, the pressure received by the second resin composition from the mold 20 is increased, the impregnation of the second resin composition is promoted, and the second resin composition is located near the outer surface of the fiber layer 12. Is leveled and the surface becomes smooth.
In this embodiment, as shown in FIG. 9, the upper die 21 is brought closer to the lower die 22.

<Second supply stop process S16>
In the second supply stop step S16 (may be referred to as “step S16”), the tightening state is changed in step S15, the fiber layer is sufficiently impregnated with the second resin composition, and the desired supply amount is obtained. Is filled, the supply of the second resin composition is stopped. Then, it waits for the second resin composition to cure.
In the present disclosure, by supplying the second resin composition as described above as a secondary supply, it is possible to accelerate the curing of the outer layer side required for mold release, so that the productivity can be improved. Further, since the second resin composition is cured quickly by the curing accelerator, the heat associated with the reaction tends to be high, and this heat can accelerate the curing of the first resin composition impregnated in advance. It is also possible to accelerate the curing of the entire impregnated resin.

<Release process S17>
In the mold release step S17 (may be referred to as "step S17"), at least the second resin composition is cured in the step S16, and the resin composition on the outer layer side of the fiber layer 12 is cured. The preform 10 impregnated with the resin is separated from the mold 20.
In this embodiment, the upper mold 21 of the mold 20 is separated from the lower mold 22 to open the mold 20 to release the mold.

[Effects / Others]
A resin-impregnated preform 10 can be obtained by a manufacturing method including each of the above steps, a mold for that purpose, and an impregnation device. A high-pressure tank can be formed by forming a layer of glass fibers impregnated with the resin on the preform 10 impregnated with the resin, if necessary.
According to the present disclosure, when the fiber layer is impregnated with the resin by the RTM impregnation technique, a plurality of types of resin compositions having different curing rates are used in order. Specifically, the first resin composition whose curing rate is delayed is used on the inner layer side, and the second resin composition whose curing rate is increased by the curing accelerator is used on the outer layer side for impregnation. Therefore, even if the fiber layer is thick, the first resin composition can be impregnated up to the inner layer side, so that appropriate impregnation is performed. On the other hand, since the second resin composition is impregnated on the outer layer side, the outer layer side can be rapidly cured and released from the mold. Further, the heat generated during the curing of the second resin composition accelerates the curing of the first resin composition.
As a result, both homogeneous impregnation and high-speed curing required for mold release can be achieved, and cost reduction by improving productivity and high performance and high quality by homogeneous impregnation can be realized at the same time. Can be done.

10 Preform 11 Liner 12 Fiber layer 20 type 21 Upper type 22 Lower type 30 Impregnation device 31 Main agent tank 33 Hardener tank 34 Hardener accelerator tank 35 Switching valve 37 Mixer

Claims (1)

A method for manufacturing a fiber-reinforced resin molded product, which comprises a step of impregnating a fiber layer with a resin.
A step of supplying the first resin composition in which the main agent and the curing agent are mixed to the fiber layer, and
A step of supplying a second resin composition in which a main agent, a curing agent and a curing accelerator are mixed to the fiber layer when the first resin composition reaches a curing start temperature or higher is included. ,
A method for manufacturing a fiber-reinforced resin molded product.

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