JPH05111933A - Production of molded form of hardening resin - Google Patents

Abstract

PURPOSE:To obtain a method for producing a molded body of hardening resin lightweight. CONSTITUTION:In the case of molding hardening resin by resin injection molding, reaction injection molding and resin transfer molding or the like, a lightweight rigid foam is fixed to the inside of a mold as the core of a molded form and the hardening resin is molded. Thereby the molded body of hardening resin is excellent in mechanical characteristics. Moreover the molded form is made lightweight by a method easy in molding and excellent in productivity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to weight reduction of a curable resin molded product.

[0002]

2. Description of the Related Art Conventional methods for producing a curable resin molded product having a hollow structure include a filament winding method and
There are molding methods using honeycomb materials and prepregs, and these molded products are used as structural materials and large-sized molded products, but the manufacturing process is complicated and many manual work is required, so it is necessary to manufacture large-sized molded products and small-quantity products. Suitable, but unsuitable for mass production of the same.

Further, a method for producing a molded article by using a core material covered with a suitable reinforcing fiber such as glass fiber or carbon fiber in polystyrene foam or polyurethane foam (JP-A-1-317730, JP-A-2-47012). However, there is a drawback that the weight distribution cannot be controlled accurately because the resin or resin raw material melted during molding invades the core foam, and the core foam may be covered with reinforcing fibers. Further, there is a drawback that a post-treatment is required.

[0004]

The present inventors have overcome such drawbacks, have excellent productivity, have excellent mechanical properties,
Moreover, as a result of intensive studies aimed at reducing the weight of the curable resin molded product, the object was achieved by using the lightweight rigid foam as the core material without changing the usual injection molding machine, manufacturing method, and raw material, thus completing the present invention. did.

[0005]

That is, the present invention is characterized in that a lightweight rigid foam is used as a core material in molding a curable resin by resin injection molding, reaction injection molding, and resin transfer molding. It is to provide a method for producing a curable resin molded product.

The light and hard foam used in the present invention is a foam such as polymethacrylimide resin, polyimide resin, phenol resin, aramid resin, polysulfone resin, polyether sulfone resin, polyphenylene resin, and the like. The density is lower than the density of plastics used in the resin injection method, reaction injection molding method and resin transfer molding method, and has a closed cell structure, and the foamed material is molded under the molding temperature and molding pressure of these molding methods. It is preferably one that does not shrink or deform.
More preferably, the dimensional stability temperature measured according to DIN 53424 is 135 ° C. or higher, preferably 135 ° C. or higher.
It is a lightweight rigid foam having a closed cell structure of 300 ° C., a density measured according to DIN 53420 of 0.3 g / cm ³ or less, and an independent foaming structure, and the dimensional stability temperature of the lightweight rigid foam is less than 135 ° C. The foam is deformed when the resin is cured, and lowering the curing temperature undesirably increases the molding time. In addition, the density of lightweight rigid foam is 0.3
When it is more than g / cm ³ , the effect of reducing the weight of the curable resin molded product becomes small and the effect of the present invention cannot be achieved. By satisfying these conditions, penetration of a curable resin into the foam can be prevented, the weight distribution of the molded product can be controlled with high accuracy, and the mechanical strength of the molded product can be improved by the pseudo hollow structure. it can.

The curable resin used in the present invention includes:
Any curable resin used in resin injection molding, reaction injection molding, and resin transfer molding can be used, for example, polyurethane resin, unsaturated polyester resin, unsaturated polyesteramide resin, phenol resin. , Urea resin, etc.

When the molded article of the present invention is produced, the lightweight rigid foam may be fixed in the center of the mold and molded by a usual molding method. The molding can be performed under the conditions applicable to the resin used.

[0009]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.

(Example 1) A rigid foam having a closed cell structure made of polymethacrylimide resin cut out to a center of a 6 × 6 × 10 cm mold to a size of 4.8 × 5 × 9 cm, and a dimensional stability temperature of 180 ° C. , With a density of 0.110 g / cm ³ (Rohacell 110, sold by Daicel Chemical Industries, Ltd.),
Unsaturated polyester resin (Dainippon Ink and Chemicals, Inc.)
Made, polylite 8104) 30 parts, calcium carbonate 5
1.4 parts, 17 parts glass fiber, 1 part zinc stearate,
An injection temperature of 80 ° C., an injection pressure of 5.0 kgf / cm ² , was prepared by kneading 0.6 parts of benzoyl peroxide paste.
Resin injection molding was performed under the conditions of a mold temperature of 110 ° C., an injection time of 5 seconds, and a holding time of 20 minutes to manufacture a molded product. When the weight of the molded product is measured, it is 353 g.
The apparent density was 0.981 g / cm ³ . No air bubbles or unfilled parts were found in the polyester resin molded product either by nondestructive inspection by an X-ray transmission apparatus or by destructive inspection. No permeation of polyester resin or deformation of pores was observed in the foamed product.

(Comparative Example 1) The same mold as in Example 1 was used, the same resin was used, the same conditions were used, but only the injection time was 10 seconds, and resin injection molding was performed without using a foam. The weight of the molded product is 814 g (apparent density 2.261 g / cm
³ ) was.

[0012]

EFFECTS OF THE INVENTION According to the present invention, a curable resin molded product has excellent mechanical properties, is easy to mold, and can be made into a lightweight product by a method with excellent productivity. It can also be well controlled.

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Claims (2)

[Claims] 1. A method for producing a curable resin molded article, which comprises using a lightweight rigid foam as a core material in molding a curable resin by resin injection molding, reaction injection molding, and resin transfer molding. 2. The lightweight rigid foam of claim 1 is DIN 5
The dimensional stability temperature measured by 3424 is 135 ° C. or higher, and the density measured by DIN53420 is 0.
A method for producing a curable resin molded product, which has a closed cell structure of ³ g / cm ³ or less.