JP2986559B2 - Method for manufacturing flat lightweight structure - Google Patents

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 flat, lightweight 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 a fiber reinforced resin (FRP) and the center is a lightweight layer.

[0002]

2. Description of the Related Art Various types of structural panels are known for buildings such as houses, transport vehicles such as aircraft, railways, automobiles, ships, and containers. Among them, lightweight, sound insulation,
There is a structural panel having characteristics such as heat insulating properties, in which a foam is used as a core body, and on both sides thereof, a surface layer of a thermosetting resin such as unsaturated polyester or epoxy reinforced with fiber such as glass fiber is used.

[0003] As a well-known technique, there is a method in which a plate-like rigid foam is sandwiched between prepregs of reinforcing fibers, and compression molding is performed. In addition, there is a portion where the adhesion at the interface between the core and the reinforcing fiber is not sufficient, and the quality tends to vary. It is not enough to obtain a sufficient bending strength, and as described in JP-B-54-14156,
Attempts have been made to put a rigid member in the core as a reinforcing member in order to increase the structural strength of this type of panel, but it is difficult to reliably adhere this member to the core. Panel fabrication becomes complicated.

[0004] Also, a method of filling a liquid crystal foaming curable resin into the voids of the honeycomb of the honeycomb sandwich structure (Japanese Patent Publication No. 60-21540) is known. In this case, the liquid foaming curable resin constitutes the foam and impregnates the fibrous sheet. For this reason, it is necessary to select a material having particularly good impregnating properties as the fibrous sheet. Not only is the physical property sacrificed, but the gas due to foaming remains on the fiber surface as voids, which reduces the strength of the structure and frees the pressure required to impregnate the fibrous sheet. The specific gravity of the foam portion formed is higher than that of foaming, and the molded panel is difficult to use in applications where lightness is important. In addition, liquid foaming resin such as polyurethane foams during injection,
Before the honeycomb material is pressed by the fibrous sheet to form a closed space, troubles such as overflow from the void are likely to occur.

[0005] Further, a method of filling expandable thermoplastic resin particles such as unexpanded polystyrene beads into the void portions of the honeycomb of the honeycomb sandwich structure is known. In this case, a fibrous sheet is prepreg-prepared in advance. It is necessary to bond the honeycomb with the honeycomb. If the fibrous sheet and the honeycomb material are pressed before the expansion of the expandable thermoplastic resin particles filled in the voids to form a closed space, there occurs a problem that there is no escape for gas when the expandable thermoplastic resin particles expand. Under conditions where the expandable thermoplastic resin particles filled in the voids are expanding,
Before the honeycomb material is pressed by the fibrous sheet to form a closed space, a trouble that overflows from the gap easily occurs. Furthermore, in this case, the specific gravity of the formed foam part is higher than that of the free foam in order to maintain the pressure necessary for obtaining sufficient adhesion between the fibrous sheet (prepreg) and the foam, and the molded panel is lighter. There are difficulties in applications where performance is important.

[0006]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and provides a simple and stable quality plate-shaped structure having light weight and sufficient bending strength. It is intended to provide a method that can be manufactured.

[0007]

SUMMARY OF THE INVENTION The object of the present invention is to provide a method for manufacturing a light-weight plate-like structure, which comprises the steps of (a) placing a light-weight solid substance in a gap between upper and lower fibrous sheets being fed in parallel. (B) applying a mixture of heat-expandable resin particles and a liquid thermosetting resin to the fibrous sheet and / or lightweight solid, (c) upper and lower fibrous sheets By guiding a molding member having a zone for holding and heating a partition member containing a lightweight solid material, the expansion of the thermally expandable resin particles by heating in the molding portion causes the upper and lower fibrous sheets and the partition member to expand. , And a part of the thermosetting resin is made to permeate into the upper and lower fibrous sheets to reach the surface layer portion and is cured, thereby achieving the present invention.

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 view of the steps showing one embodiment of the method of the present invention. In FIG. 1, a lower fibrous sheet (1), which is a molding material, is drawn out of a roll and provided to a lower conveyor (11), and a mixture of thermally expandable resin particles and a liquid thermosetting resin is injected into an injection machine. It is applied onto the fibrous sheet (1) through the nozzle of (22). Next, the plurality of partition members (3) containing light solids therein are sequentially set by the feeder (21) so as to be arranged on the fibrous sheet (1). Subsequently, a mixture of the heat-expandable resin particles and the liquid thermosetting resin is applied onto the partition member (3) through the nozzle of the injector (23).

Next, the upper fibrous sheet (2) is pulled out from the roll, and is pressed on the upper conveyor (12) in a state where it is placed on the partition member (3) while being heated by the heating zone (13) of the forming section. Sent to Heating zone (13)
The heat-curable resin particles previously applied are expanded by heating, and then solidified and then cured simultaneously with the thermosetting resin. At this time, at least a part of the thermosetting resin rises and falls due to the pressure caused by the expansion of the particles. Permeates into the fibrous sheet, hardens to the surface layer portion, becomes a light-weight structure (4) in the form of a flat plate, emerges from the molded portion, is taken off by a take-off device (not shown), and becomes an ear if necessary. It is cut to a fixed size after cutting both ends. The partition member (3) is shown in FIG.
As shown in the figure, a fiber mat (3a) is provided in the partition member.
And lightweight solids such as plastic foam (3b)
And built-in.

The heating zone (13) of the molding section may be one in which the upper and lower surfaces are merely constituted by endless belts, but there is a problem that resin or the like cured by molding comes out as burrs. In this case, as described in Japanese Patent Publication No. 60-21540, a cylindrical passage having an inlet and an outlet and having a plate-shaped cross section is formed, and the wall surface of the passage is an upper surface. -The lower surface and the left and right side surfaces may be constituted by endless belts.

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

FIG. 2 is a schematic view of a process showing another embodiment of the present invention. In FIG. 2, the lower fibrous sheet (5
1) is pulled out from the roll, supplied to the lower conveyor (61), and a mixture of the thermally expandable resin particles and the liquid thermosetting resin is applied onto the sheet via the nozzle of the injector (72). Next, using the feeder (71), a partition member (53) having a configuration as shown in FIG. 4 is sequentially set on the fibrous sheet. A lightweight solid such as polyimide foam having a specific gravity of 0.05 cut into a rectangular parallelepiped by the robot (74) is placed in each of the gaps of the partition members (53). A mixture of the heat-expandable resin particles and the liquid thermosetting resin is also applied to the partition member (53) via the nozzle of the injector (74). The upper fibrous sheet (52) is pulled out from the roll and is put on the lower fibrous sheet by the upper conveyor (62), and has a heating / cooling function, and is a laminate of the laminate to be obtained. It is pressed with heating by a press forming device (63) having a thickness control function for keeping the thickness constant. Due to this heating, the thermosetting resin is cured and the thermosetting resin is cured to form a molded body. At this time, due to the internal pressure due to the expansion of the particles, at least a part of the thermosetting resin is formed into upper and lower fibers. Into a light-weight plate-shaped structure (54) which penetrates the porous sheet to reach the surface layer and is hardened.
3) It is taken out by the take-up device (64), and if necessary, cut at both ends to be ears, and then cut to a fixed size.

The structure of the product 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 during and move while 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-forming device (63) works so as to heat it when it is closed, and adjusts the temperature so that cooling starts when the molding is finished. Even when the molded plate-shaped structure is cooled and taken out, when the quality becomes stable, the press molding device (63) opens and the structure moves.

In the present invention, if necessary, a preheating device is provided before (upstream of) the press molding device (63), and the temperature is raised to a temperature just before the thermally expandable resin particles expand. In addition, the time for press molding can be shortened.

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

For the purpose of improving the mechanical properties of the molded article together with these thermally expandable resin particles and imparting flame retardancy, inorganic hollow particles such as glass balloons and shirasu balloons, milled glass, silicon carbide and the like.・ Whisker,
Additives such as short fibers such as mica, iron powder, calcium carbonate and silica sand, powders 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, polyamide resins, and the like. 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.

To apply the mixture of the heat-expandable resin particles and the liquid thermosetting resin, the mixture is applied to the upper and lower fibrous sheets on the side (inside) in contact with the partition member, or a lightweight solid is applied. Apply to the surface of the contained partition member. These means can be used in combination. In short, it suffices to apply the mixture so that the mixture is present in the vicinity of both joints between the upper and lower fibrous sheets and the partition member containing the lightweight solid material during molding. As an application method, any means such as spraying, roller coating, and application by a brush can be adopted.

As the fibrous sheet, those known as having a function as a reinforcing material are used. Specific examples of the material include glass fiber, carbon fiber, silicon carbide fiber, and metal fiber. , Aramid fibers, polyarylate fibers, polyolefin fibers, and mixed fibers of two or more thereof are preferred. In addition to these fibers, polyester fibers, polyamide fibers, viscose fibers, natural fibers, asbestos, and the like can also be used. These fibers may be short fibers or long fibers, and may be whiskers, but continuous fibers are particularly preferable. These are used in the form of a sheet such as a woven fabric, a knitted fabric, a nonwoven fabric, a roving, a web, a mat, and a paper.

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 be laminated and used. Can be used in a laminated state.

When the sheets are laminated in two or more layers, at least one of the upper and lower fibrous sheets is in contact with the mixture of the heat-expandable resin particles and the liquid thermosetting resin on the side of the heat-expandable resin after expansion. By arranging a porous sheet that does not substantially pass the particles but allows the liquid thermosetting resin to pass, only the liquid thermosetting resin permeates the fibrous sheet constituting the reinforcing material and reaches the surface layer portion. By tightening and curing, the surface layer portion of the molded body can be a dense fiber reinforced resin containing no thermally expandable resin particles, and can cope with a case where a high mechanical property is particularly required for the product. . As the porous sheet, a woven fabric, a knitted fabric, a nonwoven fabric, a web, a paper, a wire mesh, or a porous film having a small opening is used.

Further, a film may be provided on each or one of the upper and lower fibrous sheets, or on one or both sides of the opposite surface which is in contact with the mixture of the thermally expandable resin particles and the liquid thermosetting resin.

As a film, when it comes out from a press as a flat plate-shaped lightweight structure by the method of the present invention,
A release film that improves 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 as a product. There is something excellent. The material of the film may be selected from metals such as plastic, aluminum, and iron, paper, and those obtained by coating the surface of a cloth with a resin, if necessary.

As for the structure of the partition member used in the present invention, those having a fine partition which can be expected to have a greater reinforcing effect are reduced in the size of the flat lightweight solid material entering each partitioned section. , Handling may be troublesome. Therefore, in the case of a plate-like material, a partition can be selected from a so-called honeycomb core material having a hexagonal partition, and a partition that divides the partition vertically and horizontally as shown in FIG.

The material of the partition member is not particularly limited, and paper, plastic, metal such as aluminum, wood, or the like is used as the material.

A preferable condition for the partition member is that the reinforcing material of both surface layers is vertically connected by the partition member through the core portion in the finished flat plate-shaped lightweight structure. For this reason, it is preferable that the height of the partition member is equal to or higher than the height of the lightweight solid that fills the gap.

The lightweight solid material to be contained in the partition member can be appropriately selected from light wood such as foam, hollow body and balsa regardless of organic, inorganic or metal.
Further, the number of the solid matter is not limited to one for each partition of the partition member, and may be plural. Also, the shape does not have to match the shape of the section.

When it is particularly important to reduce the weight of the structure to be formed, the solid itself is as light as possible (for example, when the specific gravity is 0.1 mm).
2 or less), and when the liquid thermosetting resin penetrates to the inner central part by the expansion pressure generated by the expansion of the heat-expandable resin particles, more liquid thermosetting resin Since a resin is required and the weight increases, a structure that is difficult to penetrate is preferable. In the case of foams, foams with closed cells are preferred over foams with open cells. However, these are not required.

When it is necessary to partially add necessary functions to a product structure, for example, it is used as a panel,
When a screw is to be screwed into a specific portion, as shown in FIG. 3, an appropriate material such as a fiber mat, a three-dimensional woven fabric, or a knitted fabric can be put in the space of the partition member at a corresponding position instead of a lightweight solid material. . When a special concentrated load is applied, metal can be inserted and reinforced only in the gap of the partition member at the corresponding position.

In addition, when the heat-expandable resin particles expand from the side surface during molding, the thermosetting resin accompanied by air and gas generated in the replaced voids oozes out and becomes burrs during operation. In order to prevent troubles, for example, a braid made of high-density glass fiber has a square cross section, and it is hardened with resin while keeping the mesh not to be completely crushed. Can be provided on either side surface of the upper and lower fibrous sheets. In this case, the object can be achieved by that the thermosetting resin accompanied by the gas oozes out of the blade surface in contact with the inside and stops inside the blade. After molding, this part is cut off as an ear and removed.

[0032]

As described above, according to the method of the present invention, a mixture of the heat-expandable resin particles and the thermosetting resin is formed between the upper and lower fibrous sheets by utilizing the expansion pressure of the heat-expandable resin particles during molding. And, after filling the voids present in the sheet, the upper and lower reinforcing fiber parts are pressed against the wall surface of the molded part by the internal pressure, and a part of the thermosetting resin is impregnated into the upper and lower fibrous sheets,
A uniform force acts on the whole, and a strong connection can be obtained. Particularly, on the side of the upper and lower fibrous sheets that are in contact with the mixture of the thermo-expandable resin particles and the liquid thermosetting resin, the heat-expandable resin particles after expansion are not substantially passed, but the liquid thermosetting resin is passed through. When the quality sheets are laminated, the upper and lower fibrous sheets become dense FRP with a high density of reinforcing fibers.

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

[Brief description of the drawings]

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

FIG. 2 is a schematic process diagram illustrating another embodiment of the method of the present invention.

FIG. 3 is a plan view showing an example of a partition member containing a lightweight solid substance.

FIG. 4 is a plan view showing another example of a partition member that does not include a light-weight solid substance.

[Explanation of symbols]

1, 2, 51, 52 Fibrous sheet 3 Partitioning member incorporating light solids 3a Fiber mat 3b Foam which is a light solid 4 Flat plate / light structure 11, 61 Lower conveyor 12, 62 Upper conveyor 13 Heating zone 21, 71 Partition member feeder 22, 23, 72, 73 Injector for thermally expandable particles and thermosetting resin 51, 52 Fibrous sheet 53 Partition member having a hollow section 63 Press-forming device 64 Pick-up device 74 Robot that puts lightweight solid matter into partition member

Claims (5)

(57) [Claims] (1) When manufacturing a flat lightweight structure, (a) installing a partition member containing a lightweight solid substance in a gap between upper and lower fibrous sheets being fed in parallel; b) applying a mixture of the heat-expandable resin particles and the liquid thermosetting resin to the fibrous sheet and / or the lightweight solid; and (c) a partition containing the lightweight solid by the upper and lower fibrous sheets. Guided to a molding section having a zone for sandwiching and heating the member, and by expanding the thermally expandable resin particles by heating in the molding section, fill the closed space surrounded by the upper and lower fibrous sheets and the partition member, A manufacturing method characterized in that a part of a thermosetting resin is penetrated into upper and lower fibrous sheets to reach a surface layer portion and is cured. 2. The method according to claim 1, wherein the upper and lower fibrous sheets do not substantially pass through the heat-expandable resin particles after expansion on the surfaces in contact with the mixture of the heat-expandable resin particles and the liquid thermosetting resin. 2. The method according to claim 1, wherein a porous sheet through which the resin passes is arranged. 3. A film is disposed on each of one or both of the upper and lower fibrous sheets on the side not in contact with the mixture of the thermally expandable resin particles and the liquid thermosetting resin. The method according to claim 2. 4. A structure in which the specific gravity of a light-weight solid material sandwiched between voids between fibrous sheets is 0.2 or less, and a liquid thermosetting resin does not easily penetrate into the center of the interior. The method according to claim 1, 2 or 3, wherein: 5. A material, such as a fiber mat, a three-dimensional woven fabric, or a knitted material, is inserted into a specific portion of the partition member in place of a lightweight solid material. Or the manufacturing method according to claim 4.