JPH04241936A - Preparation of plate-shape composite material having foam core - Google Patents

Abstract

PURPOSE:To obtain a composite material strongly bonded by uniform internal pressure and having stable quality by such a simple process that a plate-shape foam material is sandwiched between upper and lower fiber sheets and a mixture of heat-expansible resin particles and a thermosetting resin is applied to the sheets and the foam material to heat the whole. CONSTITUTION:A lower fiber sheet 51 is supplied to a lower conveyor 61 and a mixture of heat-expansible resin particles and a liquid thermosetting resin is applied to the sheet from the nozzle of an injector 72. Next, a plate-shape foam material 53 is set on the fiber sheet by a feeder 71 and the aforementioned mixture is applied to the foam material 53 from the nozzle of an injector 73. Subsequently, an upper fiber sheet 52 is superposed on the plate-shape foam material 53 arranged on the lower fiber sheet 53 and the whole is heated and pressed by a press molding apparatus 63. At this time, the thermosetting resin is partially infiltrated into the upper and lower fiber sheets by the pressure due to the expansion of the resin particles to be cured.

Description

[Detailed description of the invention]

0001

[Industrial Application Field] The present invention is a lightweight plate-like composite material in which a foam, a surface material of a fiber-reinforced resin layer sandwiching the foam, and a backing material are integrally laminated together and molded continuously or intermittently. It's about how to do it.

0002

[Prior Art] A plate-like composite material in which a fiber-reinforced resin layer is used as a surface material and a lining material, and a foam is sandwiched between the layers, is used as an exterior wall material, lining material, roofing material for buildings, automobiles, railways, etc. It is widely used as it is suitable for the outer layer of transportation equipment such as ships, as well as containers for land and sea.

Conventionally well-known methods for manufacturing this type of plate-shaped composite material include a method in which a plate-shaped foam material is sandwiched between fiber-reinforced resin plates, an adhesive is applied, and compression molding is performed; There is a method in which a plate-shaped foam material is sandwiched between reinforced fiber prepregs and compression molded, but both require a step in which fiber-reinforced resin plates or prepregs are made in advance. In addition, the reinforcing fiber prepreg must be carefully made so that the reinforcing fibers are sufficiently impregnated with resin and there are no air bubbles. Otherwise, air bubbles will remain in the surface layer material of the finished plate-shaped composite material, which will not only have a poor appearance but also usually not have sufficient mechanical properties such as strength. Furthermore, in either case, pressure distribution occurs on the pressed surface due to compression molding, and there are areas where adhesion is insufficient at the interface between the core and the upper and lower surface layers, which tends to cause variations in quality.

0004

[Problems to be Solved by the Invention] The present invention solves the above-mentioned problems and makes it possible to easily and efficiently produce molded products made of plate-shaped composite materials having a foam core with stable quality. This is an attempt to provide a method that allows you to do so.

[0005]

[Means for solving the problem] The above problem is solved when manufacturing a plate-like composite molded product having a foam core.
a) sandwiching a flat foam material between upper and lower fibrous sheets that are being fed in parallel; (b) inserting a mixture of thermally expandable resin particles and liquid thermosetting resin into the fibrous sheet and/or the foam material; (c) The flat foam sandwiched between upper and lower fibrous sheets is introduced into a molding section equipped with a heating zone, and the thermally expandable resin particles expand due to heating in the molding section. This is achieved by the method of the present invention, which is characterized in that a portion of the thermosetting resin is infiltrated into the upper and lower fibrous sheets to reach the surface layer and harden.

Next, specific embodiments of the method of the present invention will be explained with reference to the drawings. However, it goes without saying that the present invention is not limited to these embodiments.

FIG. 1 is a schematic diagram of steps illustrating one embodiment of the method of the present invention. In FIG. 1, a fibrous sheet (1) of the lower molding material is pulled out from a roll and supplied to a lower conveyor (11), and a mixture of thermally expandable resin particles and liquid thermosetting resin is injected into an injection machine (22). ) is applied onto the sheet (i.e. the side in contact with the foam) through a nozzle. Next, a plurality of flat forms (3) are fed to a feeding machine (21).
are sequentially set on top of this fibrous sheet. A mixture of thermally expandable resin particles and liquid thermosetting resin is applied onto the set flat form (3) through the nozzle of the injection machine (23).

Next, the upper fibrous sheet (2) is pulled out from the roll, placed over the flat foam (3), and pressed on the upper conveyor (12) while passing through the heating zone (13). It is sent to the equipped molding section. Due to the heating, the thermally expandable resin particles expand and solidify, and the thermosetting resin is cured. At this time, due to the expansion force of the particles, at least a part of the thermosetting resin becomes fibrous. It penetrates into the sheet and reaches the surface layer, and comes out from the molded part as a plate-shaped composite material (4) in which the fiber-reinforced resin layer on the surface layer and the foam core in the center are integrally molded. The paper is picked up by a pick-up device, and if necessary, both ends that will become ears are cut off and then cut into regular lengths.

[0009] The heating zone for molding may simply consist of endless belts on the upper and lower surfaces, but if the problem is that resin hardened during molding comes out as burrs, 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 section, and the walls of the passage are the upper and lower surfaces. Also, it is possible to use one in which the left and right sides are made up of endless belts.

[0010] Furthermore, in order to lower the temperature of the compact after passing through the heating zone, a cooling zone may be provided downstream of the heating zone to actively cool the compact.

FIG. 2 is a process diagram illustrating another embodiment of the present invention. In FIG. 2, a lower fibrous sheet (51), which is a molding material, is pulled out from a roll and supplied to a lower conveyor (61), and a mixture of thermally expandable resin particles and liquid thermosetting resin is injected into an injection machine (72). ) is applied onto the sheet through a nozzle. Next, a plurality of flat forms (53
) are sequentially set on this fibrous sheet using a feeder (71). A mixture of thermally expandable resin particles and liquid thermosetting resin is placed on top of the flat form (53) using an injection machine (
73) is applied through the nozzle.

Next, the upper fibrous sheet (52) is pulled out from the roll and passed through the upper conveyor (62) to the flat foam (53) arranged on the lower fibrous sheet (51).
), and then heated and pressed in a press molding device (63) which has heating and cooling functions and has a thickness control function to make the thickness of the composite material constant. Due to the heating, the thermally expandable resin particles expand and then solidify, and the thermosetting resin also hardens. At that time, due to the expansion force of the particles, at least a part of the liquid thermosetting resin penetrates the upper and lower fibrous sheets, reaches the surface layer, and hardens. A composite material (54) having a shaped foam core comes out of the press molding device (63), is taken up by a take-off device (64), and if necessary, both ends to form ears are cut and then cut to a regular length. be done.

[0013] The composite material (54) of the product is transferred to a take-up device (64).
) and the upper and lower conveyors (61) and (62) are interlocked to pull out or move by other methods,
It stops while the press molding device (63) is closed, and moves while it is open. The moving distance is determined by press molding equipment (63
) is preferably shorter than the effective length in the machine direction of the press plate. 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 composite material is cooled and its quality is stable even when taken out, the press molding device (63) is opened and the composite material is moved.

[0014] If necessary, press molding equipment (63
It is also possible to shorten the press molding time by providing a preheating device (not shown) in front of ) to heat the thermally expandable resin particles until just before they expand.

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

[0016] Together with these thermally expandable resin particles, inorganic hollow particles such as glass balloons and slushy 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 be added.

[0017] As the liquid thermosetting resin, epoxy resin, polyurethane resin, unsaturated polyester resin, polyvinyl ester resin, polyimide resin, phenol resin, polyamide resin, etc. can be used, but the resin is not limited to these. It should be noted that these resins are preferably liquid at room temperature, but may be liquid at the molding temperature, and solid at room temperature can also be used.

As the fibrous sheet, those known to have a function as a reinforcing material are used. Specifically, the materials include glass fiber, carbon fiber, silicon carbide fiber, metal fiber, and aramid. Preferred are fibers, polyarylate fibers, polyolefin fibers, and mixed fibers of two or more of these fibers. 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, knitted, nonwoven, roving, web, mat, and paper.

[0019] The fibrous sheet may be used alone, but
It can be used by laminating sheets of the same type or different types, and can also be used by laminating films, sheets, etc. other than fiber sheets.

In the case of such lamination, the expanded thermally expandable resin particles are not substantially allowed to pass through the surfaces of the upper and lower fibrous sheets that are in contact with the thermally expandable particles and the liquid thermosetting resin (that is, the inner surface side), but the liquid By placing a porous sheet through which the thermosetting resin can pass, only the liquid thermosetting resin can penetrate into the fibrous sheet that makes up the reinforcing material, reach the surface layer, and harden. Since the surface layer portion of the molded body can be made into a dense fiber-reinforced resin layer that does not contain thermally expandable resin particles, it is also possible to cope with cases where mechanical properties are particularly required of the molded body. As this porous sheet,
Examples include woven fabrics, knitted fabrics, nonwoven fabrics, webs, paper, wire mesh, and porous membranes.

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

[0022] The film may include a release film that improves release properties from the conveyor and protects the product when it comes out of the press as a plate-shaped foam core composite;
There are pre-printed films that become the surface layer of products, and materials that are preferred for products and have excellent adhesion to the thermosetting resin used. The material for the film can be selected from metals such as plastic, aluminum, and iron, paper, and cloth coated with a resin, as required.

In the method of the present invention, the material of the flat foam material sandwiched between the upper and lower fibrous sheets may be organic, inorganic, or metal. However, when used as a structural panel, the use of flexible foams with closed cells may be undesirable as it results in a composite material with poor mechanical properties.

[0024] Rigid foams are therefore often preferred. In addition, when weight reduction is particularly important, it is important that the flat form itself is as light as possible, and furthermore, the expansion pressure generated by the expansion of the thermally expandable resin particles causes the liquid thermosetting resin to When it penetrates to the
Since it requires more liquid thermosetting resin and increases weight, it is preferable to have a structure that is difficult to penetrate. That is, foams with closed cells are preferable to foams with open cells. Therefore, even in the case of flexible foam, closed cell foams are particularly suitable. However, this is not an essential requirement.

[0025] A foam formed by embedding an appropriate material in a specific position of a flat foam material depending on the purpose, or by mixing short fibers, lightweight hollow particles, other additives, fillers, etc. during molding of the foam material. Materials can also be used.

In other words, when it is necessary to partially impart a necessary function to a composite material that has become a product, for example, when using it as a panel and wanting to screw a screw into a specific part, it is necessary to specify the form at the corresponding position. You can hollow out the parts and fill them with suitable materials such as fiber mats, 3D woven fabrics, or knitted fabrics. If a special concentrated load is to be applied, specific parts of the foam can be hollowed out and reinforced with metal.

[0027]Although the flat foam material may be cut into appropriate dimensions in advance as shown in the figure, continuous length foam material may also be used. In the latter case, a flexible foam having continuous lengths of closed cells may be provided in much the same way as a fibrous sheet.

[0028] When applying the mixture of thermally expandable particles and liquid thermosetting resin to a fibrous sheet, it may be applied to both the upper and lower sheets, or it may be applied to only one side. good. Alternatively, it may be applied only to the front and back sides of the foam material. In either case, it should be applied to the side where the upper and lower fibrous sheets and the foam material contact (ie, the inside when formed into a molded product). The coating amount may be appropriately selected within a range that allows the resin to sufficiently penetrate into the fiber sheet during molding.

[0029]

Effects of the Invention As described above, according to the method of the present invention, when molding a plate-like composite material having a foam core, a reinforcing fiber sheet is processed in advance to make a fiber-reinforced resin board or a prepreg. No process required.

In the method of the present invention, the applied mixture of thermally expandable resin particles and thermosetting resin fills the voids existing in the upper and lower reinforcing fiber sheets by utilizing the expansion pressure of the thermally expandable resin particles generated by heating. The reinforcing fiber portions are pressed against the wall of the molding section using internal pressure while pushing out air bubbles. At the same time, the thermosetting resin is pressed against the foam by the same internal pressure and acts as the force necessary for adhesion. In other words, the method of the present invention is not compression molding in which pressure distribution is created on the surface to be pressed by external pressure, but the pressure generated by the expansion of countless thermally expandable resin particles acts as a uniform force over the whole, making it strong and strong. You can get a bond. Moreover, since the pressure required for the press is low since the internal pressure is used, equipment costs can be reduced. This is especially effective when making wide composite materials.

Furthermore, on the side of the upper and lower fibrous sheets in contact with the mixture of thermally expandable resin particles and liquid thermosetting resin,
When laminating porous sheets that substantially do not allow the thermally expandable resin particles to pass through after expansion, but allow the liquid thermosetting resin to pass through,
The upper and lower fibrous sheets can be made of dense reinforcing fibers with a high density.

[0032] Therefore, according to the method of the present invention, products of stable quality, to which functions and performances have been partially imparted as necessary, can be produced using relatively inexpensive press equipment.
It can be produced continuously or intermittently.

[Brief explanation of the drawing]

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

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

[Explanation of symbols]

1, 2, 51, 52 Fibrous sheet 3, 53 Flat foam material 4, 54 Platy composite material with foam core 11, 6
1 Lower conveyor 12, 62 Upper conveyor 13 Heating zone 21, 71 Foam material feeder 22, 23, 72, 73 Applicator for a mixture of thermally expandable particles and thermosetting resin 63 Press molding device 64 Taking-off device

Claims (4)

[Claims] Claim 1: When producing a plate-shaped composite molded product having a foam core, (a) a plate-shaped foam material is sandwiched between upper and lower fibrous sheets that are being fed in parallel; (b)
(c) applying a mixture of thermally expandable resin particles and a liquid thermosetting resin to the fibrous sheet and/or the foam material; (c) heating the flat foam sandwiched between the upper and lower fibrous sheets; A part of the thermosetting resin is introduced into the molding section provided, and a part of the thermosetting resin is infiltrated into the upper and lower fibrous sheets by expanding the thermally expandable resin particles by heating in the molding section.
1. A method for producing a plate-like composite material having a foam core, the method comprising: allowing the surface layer to reach the surface layer and curing the composite material. [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 item 2. 4. The manufacturing method according to claim 1, 2 or 3, wherein a material such as a fiber mat, a three-dimensional woven fabric, or a knitted fabric is embedded in the foam material.