JPH05147048A - Production of frp product with built-in foamed polyurethane core - Google Patents

Abstract

PURPOSE:To prevent the penetration of a resin into a core even when a low density foamed polyurethane core further reduced in wt. is used at the time of the molding of an FRP product according to an S-RIM method or an RTM method. CONSTITUTION:A foamed polyurethane core 1 having a thin resin layer 3 preliminarily formed to the surface thereof is set to a mold along with a fiber base material and a resin solution for FRP is injected in the mold. The thin resin layer 3 is provided by a general film forming method coating the surface of the foamed polyurethane core 1 with thermosetting resin type paint such as unsaturated polyester resin, epoxy resin or polyurethane paint or solvent type paint based on a thermoplastic resin such as an acrylic resin and drying and curing the coating layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a FRP having a foamed polyurethane core, which can be used for manufacturing automobile body parts, bumpers, spoilers and the like with lightweight reinforced resin.
It relates to a method of manufacturing a product.

[0002]

2. Description of the Related Art As a molding method for FRP (fiber reinforced plastic) products, RI method (resin injection method),
RTM method (resin transfer molding method),
S-RIM method (Eslim method: structural reaction injec
tion molding) is known. According to these molding methods, the FRP product has a fiber base material that is a reinforcing material set in a mold, the mold is closed, and a resin liquid (a molten resin or one liquid or two liquids) is applied from a part of the mold by pump pressure or the like. Type curable resin or reactive monomer) to impregnate a fibrous base material and cure it at room temperature or under heating.

In order to reduce the weight of FRP products, it is most effective to make the inside of the products hollow (hollow), but the manufacturing method is often complicated and difficult to carry out. For this reason, FRP products incorporating a lightweight core material are being made. In particular, for FRP products that require impact resistance such as automobile bumpers, it is better to incorporate a lightweight core material such as polyurethane foam, polystyrene, or polypropylene, rather than hollowing the inside.

Such an FRP product with a built-in core has a lightweight core material formed by foam molding, and a reinforcing fiber layer is provided on the outer surface of the core material, as disclosed in JP-A-2-215519. After that, the reinforcing fiber layer is impregnated with a resin liquid and then cured, so that it is manufactured. Light-weight polyurethane foam is often used as the core material. The foamed molding produced for use as the core material is annealed, that is, heated in air at a temperature 5 to 10 ° C. lower than the heat distortion temperature of the material for several tens of minutes to several hours, and then gradually heated. It is used as a core material after the residual internal stress is removed and unreacted components are sufficiently hardened by a heat treatment for cooling.

[0005]

An FRP product with a built-in core manufactured by a molding method such as the S-RIM method using polyurethane foam as a core material is shown in FIG. 2 [part II in FIG. 3 below (dashed line part)]. As shown in FIG. 4], the cross-sectional structure is such that the periphery of the relatively thick polyurethane foam core 1 is sealed with the FRP layer 2. Even if the polyurethane foam is lightweight, the weight of the core portion in the whole FRP product with a built-in core is large because of its relatively large volume. For example, in a shaped article such as the automobile roof 5 shown in FIG. 3, the weight of the polyurethane core portion occupies 25% of the whole. Therefore, attempts have been made to further reduce the weight of FRP products by using a low-density foamed polyurethane, which has been further reduced in weight by increasing the expansion ratio, as a core material.

However, since the low-density foamed polyurethane has low strength, when it is used as the core material, the cell is broken by the pressure of the injected resin liquid, and as shown in FIG.
There was a problem that the P resin 4 penetrates into the polyurethane foam core 1. For this reason, it was not possible to achieve the desired weight reduction. This tendency is particularly remarkable when using open-cell polyurethane as the core material.

Further, the core 1 made of the foamed polyurethane foam has the low density portion 11 at the center and the high density portion 12 at the surface layer as shown in FIG.
When a foamed polyurethane foam is cut into a core, a low density portion 11 appears on the cut surface 10 as shown in FIG. 5 and the amount of resin that permeates into the core increases, so that the weight reduction effect of the core is impaired. .. The present invention has been made for the purpose of solving the above problems, and an object of the present invention is to provide an FRP product with a built-in core which is further reduced in weight by reducing the amount of resin that permeates into the polyurethane foam core. That is.

[0008]

The method for producing an FRP product having a foamed polyurethane core according to the present invention comprises forming a thin resin layer on the surface of a foamed polyurethane core and then setting the resin layer in a mold together with a fiber base material to form an FRP. The resin liquid for injection is injected.

As the foamed polyurethane as the core material, a closed-cell or open-celled soft-to-hard polyurethane foam is generally used. However, in the method of the present invention, a foamed foam having a foaming ratio as high as possible is used. Preferably. Further, a commercially available or manufactured slab material such as Scott foam may be cut and used as the core material.

The thin resin layer may be provided by a general coating film forming method such as spray coating, brush coating or dipping.
If the thickness of the resin layer is too thin, the effect is not obtained, and if it is too thick, the weight increases. Therefore, the thickness of the resin layer is preferably about 0.05 to 0.5 mm. The coating film is usually formed on the foamed polyurethane core after the annealing treatment, but the curing of the coating material and the annealing treatment may be performed simultaneously. As the material of the resin layer to be provided, a thermosetting resin-based paint such as unsaturated polyester resin, epoxy resin, polyvinyl ester, polyurethane or the like, or a solvent-based paint of thermoplastic resin such as acrylic resin is used. In addition, an emulsion paint or the like may be used in that it does not easily penetrate into the cells of the foamed polyurethane. From the viewpoint of adhesiveness, the same type of polyurethane paint is preferable.

The material and manufacturing method of the fiber base material are not particularly limited,
From reinforcing fibers such as glass fiber, carbon fiber, aramid fiber (Kevlar fiber), ceramic fiber, metal fiber,
Polyethylene fiber, polypropylene fiber, saturated polyester fiber, polyamide fiber as a binder as required. It may be produced by mixing organic fibers such as polystyrene fibers to obtain a deposit, and subjecting the deposit to compression molding or suction filtration molding into a specific shape, or molding into a mat shape with a needle punch. The fiber base material may also be one laminated on the outer periphery of the expanded polyurethane core by a filament winding method.

In the FRP mentioned here, the matrix resin is an unsaturated polyester resin (UP) or an epoxy resin (E).
PRT, FRP which is a thermosetting resin such as phenol resin (PF), and FRT using a thermoplastic resin which can be cured at a low temperature such as methyl methacrylate and has a low viscosity.
Also includes P (Fiber reiforced thermoplastic resin).

[0013]

When the resin layer is provided on the surface of the foamed polyurethane core, the resin injected into the mold during the molding of the FRP product with the built-in core is prevented by the resin layer and does not penetrate into the core. When paint is applied to the core surface to provide a resin layer,
Since the coating material enters the cells of the core surface layer and hardens, the core surface layer is reinforced, and in the case of the open-cell cells, the opening is closed with resin. For this reason, it becomes possible to use foamed polyurethane having a lower density and lighter weight as the core material, and the weight reduction of the FRP product with a built-in core is achieved.

[0014]

EXAMPLES Examples of the present invention will be described below together with comparative examples. Example First, a 100 mm × 100 mm × 1000 mm prismatic polyurethane foam was foam-molded at a foaming ratio of 12 times, which is about 50% higher than that of a conventional one, and then this polyurethane foam which was reduced by about 30% was heated at 80 ° C. for 8 hours. And annealed over. Then, on the surface of the polyurethane foam, an unsaturated polyester resin liquid, styrene (crosslinking agent),
Unsaturated polyester resin paint consisting of benzoyl peroxide (catalyst) etc. is spray applied and the coating film is applied at room temperature to 80
Cured at ° C. The foamed polyurethane core thus produced had a resin layer having a thickness of 0.1 to 0.3 mm on the surface. After that, the fiber base material made by separate compression molding and the foamed polyurethane core are set in a molding die, and a two-part reactive resin material consisting of a liquid epoxy resin and a curing agent liquid is mixed and injected into the mold by a conventional method. A core built-in FRP molded product (test product) was manufactured by S-RIM molding.

Comparative Example 1 A core-built-in FRP molded product was manufactured according to a conventional method. That is, a FRP molding with a built-in core was carried out in the same manner as in the example except that a 100 mm × 100 mm × 1000 mm prismatic polyurethane foam was foam-molded with a foaming ratio of 8 and used as a core without forming a resin layer on the surface after annealing. Manufactured goods. Comparative Example 2 An FRP molded product with a built-in core was manufactured in the same manner as in Comparative Example 1 except that the expansion ratio was changed from 8 times to 12 times.

The weight of the FRP molded product with a built-in core manufactured by each of the methods of Example, Comparative Example 1 and Comparative Example 2 was measured.
The results shown in are obtained.

[Table 1]

As can be seen from Table 1, according to the method of Comparative Example 2, an FRP molded article which is 400 g heavier than the case of Comparative Example 1 can be obtained although the core is 400 g lighter. It was confirmed by investigating the cross section of the FRP molded product that the reason why the weight increased by about 800 g over the theoretical value was that the FRP matrix resin penetrated into the polyurethane core. On the other hand, in the FRP molded article obtained by the method of the example, even if the low-density foamed polyurethane with the expansion ratio increased by about 50% and the weight reduced by about 30% is used as the core material as in Comparative Example 2, As shown in FIG. 1, since there is the resin layer 3 for preventing permeation, the resin does not permeate into the core 1, and the weight reduction as designed was achieved.

[0018]

According to the manufacturing method of the present invention, since the resin layer is formed on the surface of the foamed polyurethane core, the FRP
The matrix resin does not penetrate into the expanded polyurethane core. Therefore, it is possible to manufacture a significantly lightweight core-containing FRP molded product by using a lightweight low-density foamed polyurethane core manufactured by increasing the expansion ratio as compared with the conventional one.

[Brief description of drawings]

FIG. 1 is a core-incorporated FRP manufactured according to an embodiment of the present invention.
It is a partial expanded sectional view showing a molded product.

FIG. 2 is a cross-sectional view of a II part (two-dot chain line part) of FIG.

FIG. 3 is a perspective view showing an automobile roof.

FIG. 4 is a partially enlarged cross-sectional view of a molded product manufactured using a low-density foamed polyurethane core by a conventional method.

FIG. 5 is a partial enlarged cross-sectional view of a molded product manufactured by using a foamed polyurethane core cut by a conventional method.

[Explanation of symbols]

 1 foamed polyurethane core 2 FRP 3 resin layer 4 permeated FRP resin

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Claims (1)

[Claims] 1. A foamed polyurethane core-containing FRP product, comprising forming a thin resin layer on the surface of a foamed polyurethane core, setting the thin resin layer in a mold together with a fiber substrate, and injecting a resin solution for FRP. Production method.