JPH03183511A - Manufacture of composite molded product - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to the production of a lightweight sandwich-shaped composite molded product whose surface layer (skin) is made of a tough reinforcing material and whose core is made of a foam. It is about law.

[Prior Art] Sandwich-like fiber-reinforced resin composite molded products having a foam core have excellent lightness and toughness, and are therefore used in a wide variety of applications such as surfing boards and turbine blades.

A method for manufacturing a 188-reinforced resin (hereinafter sometimes referred to as "RP") composite molded product having a foam core in the core is, for example, by pre-molding a foam core as the core, wrapping it with l1la as a reinforcing material, and then , a method in which the outer shell is formed by inserting it into the mold again and injecting liquid molding resin (Japanese Patent Laid-Open No. 55-82
No. 612, JP-A-61-279517, JP-A-63-
162207), or a method in which the outer shell of FRP is pre-molded, and a foamable urethane resin or the like is injected into the void in the center to foam within the void (see Japanese Patent Application Laid-Open No. 1-2).
55530) etc. are known.

However, all of these methods have the problem that the steps are diverse and the operations are complicated, and as a result, the production efficiency of molded products is low and costs are inevitably high.

On the other hand, there is a method in which a skin is placed on the cavity surface of a mold and a foamable liquid molding resin such as foamable urethane is injected into the inside of the skin to produce a foam with a skin in one step. In the method, the density is low (e.g. density 0.
89/clJ or less), it is difficult to use foaming pressure during molding to press the reinforcing material against the inner wall of the mold to give it a -C shape. Therefore, in practice, this method can be used for molding soft pads for automobiles using skin materials with sufficient extensibility, which can be applied at low foaming pressure, or for molding skin materials that have been given a shape faithfully to the mold in advance. Limited.

Another method is to use expandable thermoplastic resin particles such as boristyrene instead of the expandable liquid molding resin, soften the skin of the particles by heating, and form a foam core through volume expansion and mutual fusion. The problem with molded products is that when the usage conditions approach the molding temperature, the foam core softens, resulting in a lack of stable toughness as a molded product.

[Problems to be Solved by the Invention] The present invention solves the problem described in 1. In manufacturing a sandwich-like composite molded product having a low-density foam core in the core, the present invention solves the problem described in 1. The purpose of the present invention is to provide a method that can simultaneously form a surface layer including the following in one step, and can efficiently produce a lightweight, rigid composite molded article of any shape.

[Means for solving the problem] The above problem is a lightweight composite molded product in which the surface layer is made of a strong reinforcing material and the core is made of a foam core, and the density of the foam core is When manufacturing products of 0.89/d or less, (1) installing a reinforcing material that constitutes the surface layer of the molded product on the cavity surface of the mold; The foamable resin particles are heated and foamed by making the foamable resin particles and the liquid molding resin exist, by heating a predetermined region of the +C1 type to a sufficiently high temperature, and/or by heating the foamable resin particles to a temperature higher than that due to the reaction heat of the liquid molding resin. (d+ Curing the liquid molding resin, and θ
) is achieved by the method of the invention, which is characterized in that the composite molded article obtained is removed from the mold.

According to the method of the present invention, a mold for molding is first prepared. This mold is appropriately selected from metal molds, wooden molds, resin molds, etc., depending on the molding temperature. A reinforcing material is installed inside this mold, that is, along the inner surface of the cage of this mold. Reinforcing materials include airtight sheets such as paper and film, and generally FR.
Mill sheets (for example, woven or knitted fabrics, non-woven fabrics, etc.) made of organic fibers, inorganic SI fibers, gold l1141 fibers, etc., which are reinforcing materials used in P, are used. These reinforcing materials may be colored, patterned, or printed in advance. Also,
Two or more types of sheets may be stacked and used. The reinforcing material can also be made into a preform or treated with a resin in the form of prepreg. In this case, it is advantageous for the preform to have appropriate flexibility and to be able to be spread over the inner wall of the mold by the expansion force of the expandable resin particles.

In the method of the present invention, foamable resin particles and a curable liquid molding resin are added to the part where the foam core is to be formed in the cavity of the mold in which at least the reinforcing material is installed along the inner surface as described above. Add a third component as described below.

In this case, it is preferable that both components and the third component are mixed in advance and injected. Injections are usually performed at room temperature.

When injecting, if the mixture is fluid, it may be carried out with the inside of the mold under atmospheric pressure, but if it is injected under reduced pressure, the mixture can be uniformly distributed throughout the inside of the mold. .

However, when the amount of expandable resin particles and the third component increases, the mixture often becomes a paste-like or lumpy substance with low fluidity, and in that case, it is necessary to inject or pack them into the mold while the mold is open. :Wear.

Alternatively, the reinforcing material may be made in advance into a bag shape to fit the mold, and a mixture of expandable resin particles, liquid molding resin, etc. may be placed in the bag and then placed in the mold.

The expandable resin particles used here have a volume that increases by at least 2 times, preferably 3 to 6 times, more preferably 6 times or more when heated, and do not dissolve in the liquid curable resin used. .

In addition, in order to prevent liquid resin from entering the foaming space, it is preferable to use a material that foams into closed cells.

Such expandable resin particles include, for example, polyurethane,
Curable foams such as phenol, polyurea, melamine, polyimide and their precursors, polyvinyl chloride, polyvinylidene chloride, polyacrylonitrile, polystyrene, polyethylene, polypropylene, PPO, polyamide, polycarbonate 1-. Examples include those made of thermoplastic resins such as PBT and polyimide. For foaming the expandable resin particles, any method such as a blowing agent decomposition method, a solvent aeration method, a chemical reaction method, or a gas mixing method can be applied. In this, foaming agent 1
1r method or solvent gas r11. The method is preferably used.

In the present invention, it is preferable that the shape of the expandable resin particles is appropriately fine because it allows mixing with the liquid molding resin and improves the homogeneity of the molded product, but considering the relationship with cost. The particle size should be selected according to the purpose. Hollow heat-expandable resin particles, such as expandable beads or microcapsules, are unfoamed to begin with as fine particles, and foaming occurs due to the expansion of the hollow space of beads or capsules, so they are closed-celled. Therefore, it is preferably used in the present invention.

On the other hand, epoxy resin is a liquid molding resin.

Unsaturated polyester resin, vinyl ester resin.

Generally well-known curable liquid molding resins such as dicyclopentadiene resin and urethane resin are preferably used. The resin may be used as a raw material before reaction and curing.

The blending ratio of expandable resin particles and liquid molding resin varies depending on the density, toughness, ease of molding, etc. of the molded product obtained, but is generally 5/95 to 60/40 in terms of weight ratio.
A range of is preferred. In addition to the above two components, this mixture also contains silica balloons as a third component.

Non-expandable inorganic hollow particles like Shirasu balloons.

Non-thermally expandable elastic particles, pigments, etc. may be mixed.

We also use carbon imm, aramid fiber, silicon carbide, and potassium titanate to increase the strength of molded products.

Fibers such as boron and whiskers can also be added. Furthermore, tit agents, stabilizers, etc. can be added as necessary.

The amount of the above mixture to be injected or packed into the mold should be appropriately selected in consideration of the blending ratio of the expandable resin particles and the coefficient of volumetric expansion during heating.

Next, the temperature of this mold is increased by heating from the outside or by curing heat of the liquid molding resin, or both, and the expandable resin particles in the cavity are expanded in volume by foaming or the like.

At this time, by causing the body fa expansion of the expandable Ifi4 fat particles while the liquid molding resin maintains its fluidity, the reinforcing material is pressed against the inner surface of the mold by the expansion pressure of the expandable resin particles. , it is pushed toward the skin side of the molded product to form the desired molded product. Curing is usually performed by heating a predetermined portion of the mold to a temperature higher than the curing temperature of the liquid molding resin, and depending on the type of liquid molding resin, post-curing may be performed.

At this time, if a fiber sheet impregnated with a curable liquid resin is used as a reinforcing material, the resin impregnates inside the reinforcing material and hardens due to the expansion pressure of the expandable resin particles, and the surface layer of the molded product becomes F
It becomes RP.

In this way, the surface layer 811 (skin) is made of a strong reinforcing material (if the reinforcing material is an m-fiber sheet, it is made of FRP).
A sandwich-like lightweight composite molded product is obtained, in which the core portion is composed of a foamed core having a density of 0.897 Cd or less.

[Effect of the invention] In the method for manufacturing a composite molded article of the present invention as described above,
In manufacturing a foam-like molded product with a skin in one step, by using a combination of foamable resin particles and liquid molding resin as a foam core, (1) Foaming liquid molding such as foamable urethane 11 resin can be used. Compared to the case where resin is used, a foam core with a low density can be formed with the high pressure required to press the reinforcing material against the inner wall of the mold by taking advantage of the properties of the expandable resin particles, and when the expandable resin particles are used alone Compared to the case where the expanded foamable resin particles are surrounded by a hardened thermosetting resin, the foamed core becomes a foamed core that is stable even when exposed to temperatures near the molding temperature again. (2) It is possible to efficiently and economically produce a strong light 11-1 cup sandwich foam core composite molded product, which has been difficult to produce using conventional methods.

Such composite molded products can be widely used in fields such as various lightweight structural materials, sporting goods, vehicle and aircraft parts, mechanical parts, electrical parts, and civil engineering materials.

[Examples] Hereinafter, the method of the present invention will be explained in detail by Examples with reference to the drawings, but the present invention is not limited to the Examples.

Example 1 As shown in FIG. 1, a polypropylene-based synthetic paper 3 is placed in the opening 1 of a mold. At this time, the synthetic paper 3 does not necessarily need to be brought into close contact with the inner surface of the cavity. on the other hand,
A brief form 5 made of chopped glass and shaped along the core of the mold is installed on the core 2 of the mold. Next, polystyrene foam particles ("Eslen Beads" mouth E type manufactured by Tsukiki Kaseihin Co., Ltd.) and epoxy resin ("Epicoat J" manufactured by Yuka Shell Epoxy Co., Ltd.
"Evomate J 100/31 mixture)" in a weight ratio of 5
Composition 4 mixed at 0150 was injected and the mold was closed.

As the polystyrene foam particles expand due to the heat from the mold, the epoxy resin reacts and hardens. The molded product is removed from the mold, the paris is removed, and the outer skin made of synthetic paper 11. A product having a cross section shown in FIG. 2, which includes a core portion 12 made of foam and a glass iam reinforced resin layer 13, is obtained.

Example 2 Using the same mold as in Example 1, a three-dimensional knitted fabric of glass IIN was woven to match the shape of the skin of a molded product in which a polyvinyl chloride sheet was attached to the skin with adhesive, and the sheet surface was placed in the cavity of the mold. Install it so that it faces the cavity mold. At this time, it is not necessarily necessary to bring it into close contact with the cavity. After closing the mold, polyacrylonitrile foam resin particles (Matsumoto Microsphere, manufactured by Matsumoto Yushi Pharmaceutical Co., Ltd.) are placed on the knitted fabric.
and inorganic hollow microspheres ("Silica Balloon Co0-CEL" manufactured by Asahi Glass Co., Ltd.) and epoxy resin ("Epicoat" / "Evomate" 100/31 mixture manufactured by Yuka Shell Epoxy Co., Ltd.) were mixed at a weight ratio of 15:15 near 0. Inject something. Next, the expandable particles of polyacrylonitrile expand due to heat from the mold, and the epoxy resin reacts and hardens. The molded product is removed from the mold, the paris is removed, and the product is soaked.

[Brief explanation of drawings]

FIG. 1 shows one embodiment of the present invention, and is a simplified cross-sectional view showing a state in which raw material etc. are placed in a mold,
FIG. 2 is a simplified cross-sectional view of a lightweight composite molded product obtained in Example B of FIG. 1. In the figure, 1...Cavity type, 2...Core type, 3...Synthetic paper. 4...Mixture of expandable resin particles and liquid molding resin. 5... Preform made of glass fiber. 11...Skin made of synthetic paper. 12... Core portion consisting of foam. 13...Glass msi reinforced resin shoes

Claims (3)

[Claims] (1) A lightweight composite molded product in which the surface layer is made of a strong reinforcing material and the core is made of a foam core, and the density of the foam core is 0.8 g/cm^3 or less. During manufacturing, (a) a reinforcing material constituting the surface layer of the molded product is installed on the cavity surface of the mold, and (b) foamable resin particles and liquid molding resin are added to the part that will become the foam core after molding. (c) by heating a predetermined region of the mold to a sufficiently high temperature and/or by increasing the temperature due to the reaction heat of the liquid molding resin, the foamable resin particles are heated and foamed to cause volume expansion, and foaming is performed. (d) curing the liquid molding resin; (e) molding the resulting composite molded article; A method for producing a composite molded product, characterized by: (2) The manufacturing method according to claim (1), wherein the expandable resin particles are hollow thermally expandable resin particles. (3) The manufacturing method according to claim (1), wherein the liquid molding resin is a thermosetting resin composition that is liquid at room temperature.