JPH04241935A - Manufacture of flat and light-weight structure - Google Patents

Abstract

PURPOSE:To provide strong bonding and manufacture a product of stabilized quality in the simple process by filling a mixture of thermal expansive resin particles and thermosetting resin between upper and lower fiber sheets, impregnating the fiber sheets with resin by means of internal pressure and applying uniform force thereon. CONSTITUTION:A lower side fiber sheet 1 as a forming element is drawn out of a roll and fed on a lower side conveyor 11. A mixture of thermal expansive particles and liquid thermosetting resin is applied for coating from a nozzle of an injector 22 onto the sheet 1. Successively said mixture is applied for coating from the nozzle of the injector 23 onto a parting component 3. Then the upper side fiber sheet 2 is drawn out and transferred to a heating zone 13 of a molding section while being pressed by an upper side conveyor 12 in the state of being covered over the parting component 3. At that time, a part of thermosetting resin is permeated into the upper and lower fiber sheets by the pressure generated by the expansion of resin particles and cured on the surface to manufacture a flat structure 4.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a lightweight flat structure. More specifically, the present invention relates to a method for continuously or intermittently manufacturing a flat laminated structure having a sandwich structure in which the surface layer is made of fiber-reinforced resin (FRP) and the center layer is a lightweight layer.

0002

2. Description of the Related Art Various structural panels are known for use in buildings such as houses, transportation vehicles such as aircraft, railways, automobiles, ships, etc., and containers. Among them, lightness, sound insulation,
There is a structural panel that has characteristics such as heat insulation, which uses foam as a core and has a surface layer of thermosetting resin such as unsaturated polyester or epoxy reinforced with fibers such as glass fiber on both sides.

[0003] A conventionally well-known technique is compression molding by sandwiching a plate-shaped rigid foam between reinforcing fiber prepregs, but since compression molding is used, pressure distribution is not possible on the surface to be pressed. , there may be areas where the adhesion is not sufficient at the interface between the core and reinforcing fibers, resulting in variations in quality. Furthermore, it is not sufficient to obtain sufficient bending strength, and as described in Japanese Patent Publication No. 54-14156,
In order to increase the structural strength of this type of panel, attempts have been made to insert a hard member into the core as a reinforcing member, but it is difficult to securely bond this member to the core. Manufacture of panels becomes complicated.

[0004] There is also a method of filling the voids of the honeycomb of a honeycomb sandwich structure with a liquid foamed curable resin (
Special Publication No. 60-21540) is known. In this case, the liquid foam curable resin constitutes the foam and is also impregnated into the fibrous sheet. Therefore, it is necessary to select a material with particularly good impregnation properties as the fibrous sheet, and the mechanical Not only are the physical properties sacrificed, but the strength of the structure is reduced because the gas from foaming remains as voids on the fiber surface, and the free space required to maintain the necessary pressure to impregnate the fibrous sheet is not only compromised. Compared to foaming, the specific gravity of the formed foam portion is heavier, making the molded panel difficult to use in applications where lightness is important. Furthermore, since a liquid foamed cured resin such as polyurethane foams during injection, problems such as overflowing from the voids are likely to occur before the honeycomb material is pressed down with the fibrous sheet to form a closed space.

[0005] Furthermore, a method is known in which the voids in the honeycomb of a honeycomb sandwich structure are filled with expandable thermoplastic resin particles such as unexpanded polystyrene beads. It is necessary to treat it as such so that it can be bonded to the honeycomb. If the fibrous sheet and honeycomb material are pressed down to create a closed space before the expandable thermoplastic resin particles filled in the voids expand, a problem arises in that there is no place for gas to escape when the expandable thermoplastic resin particles expand. Under conditions where the expandable thermoplastic resin particles filled in the voids are expanding, trouble may occur where they overflow from the voids before the fibrous sheet presses the honeycomb material to form a closed space. Furthermore, in this case as well, in order to maintain the pressure necessary to obtain sufficient adhesion between the fibrous sheet (prepreg) and the foam, the specific gravity of the foam portion formed is heavier than in free foaming.
Molded panels are difficult for applications where light weight is important.

[0006]

[Problems to be Solved by the Invention] The present invention solves the above-mentioned problems, and makes it possible to easily and efficiently produce a flat plate-shaped structure that is lightweight and has sufficient bending strength. The aim is to provide a method that can produce

[0007]

[Means for solving the problem] The above problem is solved by (a) placing a lightweight solid material in the gap between the upper and lower fibrous sheets that are being fed in parallel; (b) applying a mixture of thermally expandable resin particles and liquid thermosetting resin to the fibrous sheet and/or the lightweight solid; (c) upper and lower fibrous sheets; The partition member containing the lightweight solid material is sandwiched and guided to a molding section having a heating zone, and the expansion of the thermally expandable resin particles due to heating in the molding section causes the upper and lower fibrous sheets and the partition member to separate. This is achieved by the method of the present invention, which is characterized in that the thermosetting resin fills a closed space surrounded by a thermosetting resin, and a part of the thermosetting resin is infiltrated into the upper and lower fibrous sheets to reach the surface layer and harden.

Next, two specific embodiments of the method of the present invention will be described with reference to the drawings, but the scope of the present invention is not limited thereto.

FIG. 1 is a schematic diagram of steps illustrating one embodiment of the method of the present invention. In FIG. 1, a lower fibrous sheet (1), which is a molding material, is pulled out from a roll and provided to a lower conveyor (11), and a mixture of thermally expandable resin particles and liquid thermosetting resin is fed into an injection machine. It is applied onto the fibrous sheet (1) via the nozzle (22). Next, a plurality of partition members (3) containing lightweight solid materials are successively set by the feeder (21) so as to be lined up on the fibrous sheet (1). Subsequently, a mixture of thermally expandable resin particles and liquid thermosetting resin is applied onto the partition member (3) via the nozzle of the injection machine (23).

Next, the upper fibrous sheet (2) is pulled out from the roll and placed over the partition member (3) while being pressed on the upper conveyor (12) and placed in the heating zone (13) of the forming section. sent to. Heating zone (13)
The heat-expandable resin particles previously applied expand and solidify due to heating, and at the same time the thermosetting resin hardens. At this time, at least a portion of the thermosetting resin moves up and down due to the pressure caused by the expansion of the particles. It penetrates into the fibrous sheet, hardens as it reaches the surface layer, and comes out of the molding section as a flat plate-shaped lightweight structure (4), which is picked up by a pulling device (not shown) and becomes ears if necessary. Both ends are cut and then cut to length. The above partition member (3) is shown in Figure 3.
As shown in FIG.
and lightweight solid materials such as plastic foam (3b)
It has a built-in.

[0011] The heating zone (13) of the molding section may simply consist of endless belts on the upper and lower surfaces, but the problem is that the resin hardened during molding comes out as burrs. In this case, as described in Japanese Patent Publication No. 60-21540, it is a cylindrical passage having an inlet and an outlet and having a plate-like cross-sectional shape, and the wall surface of the passage is・It is possible to use a device whose bottom surface and left and right sides are made up of endless belts.

[0012] In the method of the present invention, a cooling zone (not shown) may be provided as necessary after the heating zone (downstream side) in order to lower the temperature of the compact.

FIG. 2 is a schematic process diagram illustrating another embodiment of the present invention. In Figure 2, the lower fibrous sheet (5
1) is pulled out from the roll and fed to the lower conveyor (61), and a mixture of thermally expandable resin particles and liquid thermosetting resin is applied onto the sheet via the nozzle of the injection machine (72). Next, using the feeder (71), partition members (53) configured as shown in FIG. 4 are sequentially set on the fibrous sheet. A lightweight solid material such as polyimide foam having a specific gravity of 0.05 and cut into a rectangular parallelepiped using a robot (74) is placed in each of the gaps of each partition member (53). A mixture of thermally expandable resin particles and liquid thermosetting resin is also applied onto the partition member (53) via the nozzle of the injection machine (74). The upper fibrous sheet (52) is pulled out from the roll and placed over the lower fibrous sheet by the upper conveyor (62), and has heating and cooling functions to control the laminate to be obtained. It is heated and pressed using a press molding device (63) that has a thickness control function to keep the thickness constant. Due to this heating, the thermally expandable resin particles expand, and then the thermosetting resin hardens to form a molded body. At this time, due to the internal pressure caused by the expansion of the particles, at least a portion of the thermosetting resin is transferred to the upper and lower fibers. The sheet penetrates into the surface layer and hardens into a flat plate-shaped lightweight structure (54).
) and is picked up by the picking up device (64),
If necessary, cut off both ends to form ears and then cut to length.

[0014] The product structure is pulled out by the interlocking of the take-up device (64) and the upper and lower conveyors (61), (62), or moved by other methods, and the press-forming device (63) is closed. Stop while it's open and move while it's open. The moving distance is preferably shorter than the effective length of the press plate of the press forming device (63) in the flow direction. The press molding device (63) operates to heat the molding device when it is closed, and adjusts the temperature so that it starts cooling after molding is completed. When the molded flat structure is cooled and its quality is stable even when taken out, the press molding device (63) is opened and the structure is moved.

[0015] In the present invention, if necessary, a preheating device is provided before (upstream side) of the press molding device (63), and the temperature is raised here to the point where the thermally expandable resin particles are on the verge of expanding. , it is also possible to shorten the press molding time.

The thermally expandable resin particles used in the method of the present invention are resin particles that expand in volume in a short period of time when heated, such as polystyrene, polyvinylidene chloride, polyolefin, and polyphenylene, which are known as expandable thermoplastic resin particles. Particles such as oxides and their copolymers,
Porous elastic particles are compressed under pressure and the surface is softened by heat and coated with a resin that melts or dissolves in a liquid thermoplastic resin. However, the material is not limited to these.

[0017] Together with these thermally expandable resin particles, inorganic hollow particles such as glass balloons and shirasu balloons, milled glass, and silicon carbide are used to improve the mechanical properties of the molded product and to impart flame retardancy.・Whisker,
Additives such as short fibers such as mica, iron powder, calcium carbonate, and silica sand, powder and granules, and liquids can also be added.

On the other hand, the liquid thermosetting resin used in the method of the present invention includes epoxy resin, polyurethane resin,
Examples include, but are not limited to, unsaturated polyester resins, polyvinyl ester resins, polyimide resins, phenol resins, and polyamide resins. This resin is preferably liquid at room temperature, but may be solid (particles, powder, etc.) as long as it becomes liquid at the molding temperature.

[0019] To apply the mixture of thermally expandable resin particles and liquid thermosetting resin, either apply it to the side (inside) of the upper and lower fibrous sheets that contact the partition member, or apply a lightweight solid material. Apply to the surface of the partition member that is stored. These means can also be used in combination. In short, it is sufficient to apply the mixture so that it is present near both joints of the upper and lower fibrous sheets and the partition member containing the lightweight solid material during molding. As the method of application, any means such as spraying, roller coating, application with a brush, etc. can be adopted.

[0020]Furthermore, as the fibrous sheet, those known to have a function as a reinforcing material are used, and specific materials include glass fiber, carbon fiber, silicon carbide fiber, and metal fiber. , aramid fibers, polyarylate fibers, polyolefin fibers, and mixed fibers of two or more of these are preferred. In addition to these fibers, polyester fibers, polyamide fibers, viscose fibers, natural fibers or asbestos can also be used. These fibers may be short fibers, long fibers, or whiskers, but long fibers, particularly continuous fibers, are preferred. These are used in sheet forms such as woven fabrics, knitted fabrics, nonwoven fabrics, rovings, webs, mats, and papers.

In the method of the present invention, the above-mentioned fibrous sheets can be used alone as the upper and lower fibrous sheets, but other types of fibrous sheets can also be used in a stacked manner. It can also be used by laminating the sheets.

When laminating two or more sheets, the expanded thermally expandable resin is applied to at least one of the upper and lower fibrous sheets on the side that is in contact with the mixture of thermally expandable resin particles and liquid thermosetting resin. By arranging a porous sheet that practically does not allow particles to pass through but allows liquid thermosetting resin to pass through, only the liquid thermosetting resin can penetrate into the fibrous sheet that makes up the reinforcing material and reach the surface layer. By tightening and curing, the surface layer of the molded product can be made into a dense fiber-reinforced resin that does not contain thermally expandable resin particles, and can be used in cases where high mechanical properties are particularly required for the product. . As this porous sheet, a woven fabric, knitted fabric, nonwoven fabric, web, paper, wire mesh, or porous membrane with small openings is used.

Furthermore, a film may be disposed on each or one of the upper and lower fibrous sheets on the opposite side that is in contact with the mixture of thermally expandable resin particles and liquid thermosetting resin.

As for the film, when it comes out of the press as a flat plate-shaped lightweight structure by the method of the present invention,
A release film that improves mold release from the conveyor and protects the product, a pre-printed film that becomes the surface layer of the product, and a material that is preferred for products and has adhesive properties with the thermosetting resin used. There is something excellent. Materials for the film can be selected from metals such as plastic, aluminum, and iron, paper, and cloth coated with a resin, depending on the needs.

[0025] Regarding the structure of the partition member used in the present invention, one having fine partitions that can be expected to have a greater reinforcing effect is because the size of the flat, lightweight solid material that enters each partitioned compartment is small. , handling may be troublesome. Therefore, in the case of a plate-shaped material, in addition to a so-called honeycomb core material having hexagonal partitions, a material having partitions vertically and horizontally as shown in FIG. 4 can be selected.

The type of material for the partition member is not particularly limited, and paper, plastic, metal such as aluminum, wood, etc. can be used as the material.

[0027] A preferable condition for the partition member is that in the completed lightweight structure in the form of a flat plate, the reinforcing materials on both surface layers are vertically connected to each other by penetrating the core portion with the partition member. For this reason, it is preferable that the height of the partition member be equal to or higher than the height of the lightweight solid material filling the void.

[0028] The lightweight solid material to be placed in the partition member may be appropriately selected from foam, hollow material, and lightweight wood such as balsa, regardless of whether it is organic, inorganic, or metal. Furthermore, the number of solid objects is not limited to one per section of the partition member, but may be plural. Further, its shape does not have to match the shape of the partition.

If it is particularly important to reduce the weight of the structure to be molded, the solid material itself should be as light as possible (for example, with a specific gravity of 0.
2 or less) is important, and furthermore, when the liquid thermosetting resin penetrates to the center of the interior due to the expansion pressure generated by the expansion of the thermally expandable resin particles, more liquid thermosetting resin Since it requires resin and increases weight, it is preferable to have a structure that is difficult to penetrate. For foams, foams with closed cells are preferred over foams with open cells. However, these are not essential conditions.

[0030] When it is necessary to partially impart a necessary function to the structure that has become a product, for example, when it is used as a panel,
If you want to screw a screw into a specific location, you can insert an appropriate material such as a fiber mat, three-dimensional fabric, or knitted fabric into the gap in the partition member at the corresponding location instead of a lightweight solid material, as shown in Figure 3. . If a special concentrated load is applied, metal can be inserted and reinforced only in the gap in the partition member at the corresponding position.

[0031] Furthermore, as the thermally expandable resin particles expand from the side during molding, the thermosetting resin along with the air existing in the replaced voids and the generated gas oozes out, forming burrs and causing damage during operation. In order to prevent problems from occurring, for example, a blade made of densely woven glass fibers is made into a square cross section, and the mesh is cured with resin while maintaining the mesh to the extent that it does not collapse completely, giving it strength and preventing overflow. It can be provided as a strip material on either both sides of the upper and lower fibrous sheets. In this way, the thermosetting resin accompanied by gas oozes out from the blade surface in contact with the inside and stays inside the blade, thereby achieving the objective. After forming, this part is cut and removed as an ear.

[0032]

As described above, according to the method of the present invention, the expansion pressure of the thermally expandable resin particles is used during molding to spread the mixture of the thermally expandable resin particles and the thermosetting resin between the upper and lower fibrous sheets. After filling the voids existing in the sheet, the upper and lower reinforcing fiber parts are pressed against the wall surface of the molding part using internal pressure, and a portion of the thermosetting resin is impregnated into the upper and lower fibrous sheets.
A strong bond can be obtained by applying uniform force throughout. In particular, on the side of the upper and lower fibrous sheets that are in contact with the mixture of thermally expandable resin particles and liquid thermosetting resin, porous holes are formed that substantially prevent the expanded thermally expandable resin particles from passing through, but allow the liquid thermosetting resin to pass through. When the fiber sheets are stacked, the upper and lower fibrous sheets are made of dense FRP with a high density of reinforcing fibers.

Thus, according to the present invention, a lightweight plate-like structure with excellent mechanical properties, to which performance is partially imparted as required, can be produced with the desired stable quality through a simple process. can be produced continuously or intermittently.

[Brief explanation of the drawing]

FIG. 1 is a process schematic diagram illustrating one embodiment of the method of the present invention.

FIG. 2: Process schematic diagram illustrating another embodiment of the method of the invention.

[Fig. 3] A plan view showing an example of a partition member containing a lightweight solid object.

[Fig. 4] A plan view showing an example of another partition member that does not have a built-in lightweight solid object.

[Explanation of symbols]

1, 2, 51, 52 Fibrous sheet 3 Partition member 3a containing lightweight solid matter Fiber mat 3b Foam 4 which is lightweight solid matter Flat plate-shaped lightweight structure 11, 61 Lower conveyor 12, 62 Upper conveyor 13 Heating zone 21, 71 Partition member feeder 22, 23, 72, 73 Injector 51, 52 for thermally expandable particles and thermosetting resin Fibrous sheet 53 Partition member 63 with hollow compartment Press molding device 64 Taking device

Claims (5)

[Claims] [Claim 1] When manufacturing a flat plate-like lightweight structure, (a) installing a partition member containing a lightweight solid substance in the gap between the upper and lower fibrous sheets that are being fed in parallel;
(b) applying a mixture of thermally expandable resin particles and liquid thermosetting resin to the fibrous sheet and/or the lightweight solid; (c) enclosing the lightweight solid by the upper and lower fibrous sheets; The partition member is sandwiched and guided to a molding section equipped with a heating zone, and the thermally expandable resin particles are expanded by heating in the molding section to fill the closed space surrounded by the upper and lower fibrous sheets and the partition member. , a part of the thermosetting resin is infiltrated into the upper and lower fibrous sheets to reach the surface layer,
A manufacturing method characterized by curing. [Claim 2] The surface side of the upper and lower fibrous sheets that is in contact with the mixture of the thermally expandable resin particles and the liquid thermosetting resin is made of a liquid thermosetting resin that substantially does not allow the expanded thermally expandable resin particles to pass through. 2. The manufacturing method according to claim 1, further comprising disposing a porous sheet through which the resin passes. 3. A film is disposed on the side of each or one of the upper and lower fibrous sheets that does not come into contact with the mixture of thermally expandable resin particles and liquid thermosetting resin. The manufacturing method according to claim 2. [Claim 4] The lightweight solid material sandwiched between the fibrous sheets has a specific gravity of 0.2 or less, and the liquid thermosetting resin has a structure that makes it difficult for the liquid thermosetting resin to penetrate to the center of the interior. The manufacturing method according to claim 1, claim 2, or claim 3, characterized in that: 5. Claims 1, 2, and 3, characterized in that a material such as a fiber mat, three-dimensional woven fabric, or knitted fabric is inserted into a specific portion of the partition member instead of a lightweight solid material. Or the manufacturing method according to claim 4.