JPH06270279A - Production of synthetic resin molded product - Google Patents

Abstract

PURPOSE:To easily and well mold even a hollow object having a complicated shape by inserting a sublimable core member having a shape similar to that of a molded product in a cylindrical body and applying the pressure of the sublimited gas generated from the sublimable core member when a molding material is heated to molding temp. to the interior of the cylindrical body to expand and mold the cylindrical body. CONSTITUTION:A sublimable core member 10 is covered with a cylindrical body 9 being a silicone rubber tube and the cylindrical body 9 is covered with a molding material 8 in a thickness of about three layers and the whole is arranged in a mold 1 consisting of upper and lower molds 2, 4. When the mold is heated by a heater 7, the cylindrical body 9 is expanded by the gas generated from the sublimable core member 10 and the molding material 8 is pressed to cavities 3, 5. At this time, the molding material 8 and the cylindrical body 9 are arranged in the cavities 3, 5 in a state slackened so as to follow the shape of a product and, since the sublimable core member being a source generating gas applying inner pressure has a shape similar to that of the product, the molding material 8 uniformly and well follows the cavities 3, 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a synthetic resin molded article, and more particularly to a method for producing a hollow fiber-reinforced synthetic resin thermoplastic synthetic resin molded article by an internal pressure molding method.

[0002]

BACKGROUND OF THE INVENTION Fiber reinforced synthetic resin (FRP) is a thermosetting resin such as epoxy or unsaturated polyester, or polyethylene, polypropylene, polyamide, PPS, PE.
A thermoplastic resin such as EK is used as a matrix material, and glass fiber, carbon fiber, aramid fiber, etc. are used as a reinforcing fiber. Since it is lightweight and has excellent strength, it is familiar from the aerospace industry to construction and sports equipment. It is widely used for various products.

Centrifugal molding, pull-through molding, filament winding molding and the like are known as methods for molding FRP into a tubular or hollow shape.

In the centrifugal molding method, the inner surface of a rotating cylinder is
This is a molding method in which reinforcing fibers are wound around rollers arranged concentrically in the cylindrical body, and the reinforcing fibers are impregnated by spraying a synthetic resin for a matrix and then cured.

This molding method has a drawback that it has a relatively large diameter and can only produce a product having a simple shape, and that it requires a large apparatus and the production cost is high.

The pultrusion molding method is a method in which a reinforcing fiber base material is impregnated with a synthetic resin for a matrix and then drawn out using a mold, and the synthetic resin is cured to obtain a molded product. Only a straight pipe with the cross section of can be manufactured, and the equipment cost is high.

The filament winding molding method is a molding method in which reinforcing fibers impregnated with a synthetic resin for a matrix are wound around a mandrel, and the mandrel is pulled out after the synthetic resin is cured.

Since this molding method can increase the ratio of long fibers to reinforcing fibers, a hollow body having a relatively high strength can be obtained.
It has the drawback that only axisymmetric products can be manufactured and the equipment cost is high.

Further, since all of the above-mentioned molding methods were developed to utilize a thermosetting resin as a matrix resin, a molding material using a thermoplastic resin as a matrix resin, which has recently been actively developed. Not very suitable for molding.

Under these circumstances, it can be applied regardless of whether the synthetic resin for the matrix is thermosetting or thermosetting, and the hollow fiber-reinforced synthetic resin can be easily applied without requiring special large equipment. An internal pressure molding method has been developed as a method for molding a resin product.

The internal pressure molding method is a molding method in which a cylindrical molding material is placed in a cavity of a mold, the molding material is heated to a molding temperature, and then pressure is applied from the inside of the cylinder to inflate the material to bring it into close contact with the cavity.

In the internal pressure molding, a tubular molding material is wound around a bag formed of a material having flexibility and excellent heat resistance such as nylon or silicon rubber, or a core metal is used as a spare. Place this bag in the center of the formed molding material, place it in the mold cavity, heat the molding material to the molding temperature, and then send a pressurized fluid such as compressed air into the bag to expand the bag. The internal pressure is applied to the molding material.

[0013]

However, in the conventional internal pressure molding method, the pressure applied to the molding material depends on the expansion of the bag by the fluid for pressurization, so that the pressure cannot be locally adjusted.

Therefore, it is preferable that the hollow body to be molded has a simple pipe shape, but if the hollow body has a complicated shape, the internal pressure received by the molding material becomes partially uneven, and the wall thickness of the molded product becomes uniform. There is a drawback that does not become.

Further, if the shape of the molded product is complicated, the bag may locally expand excessively and the bag may burst.

Further, when a complicated shape is formed, the reinforcing material, which has been oriented at a predetermined degree at the portion where the molding material largely expands and deforms, faces in one direction, and the original reinforcing effect is obtained. At the same time, the matrix resin also stretched in one direction, and the molded product was partially thinned or had holes.

An object of the present invention is to solve the above-mentioned drawbacks of the prior art and to provide an internal pressure molding method capable of molding a hollow body having a complicated shape easily and in good quality.

[0018]

[Means for Solving the Problems] That is, according to the present invention, a molding material made of a fiber-reinforced synthetic resin is placed in a molding die by covering a cylindrical body made of a material having excellent flexibility and heat resistance. In the method for producing a fiber-reinforced synthetic resin molded product in which after heating to the molding temperature, the cylinder is expanded by applying internal pressure and pressed against the cavity surface, a sublimable core body similar in shape to the molded product is inserted into the cylinder. The method for producing a synthetic resin molded article is characterized in that an internal pressure is applied to a cylindrical body to expand it by the pressure of a sublimation gas generated from a sublimable core body when the molding material is heated to a molding temperature and the molded body is molded.

The tubular body which expands to give an internal pressure to the molding material is covered with a sublimable core body having a shape similar to that of the molded product in a state in which the portion which largely expands following the shape is slightly slackened, and the tubular body Similarly to the cylindrical body, the molding material to be overlaid is slightly slackened on the portion that is largely deformed following the shape of the core body.

As a result, the tubular body will not be excessively expanded and torn at the portion where it has to be largely deformed, and the molding material is also largely deformed to disturb the orientation of the reinforcing fibers. Good molding can be performed because there is no hole or hole.

Further, when the molding material is heated to the molding temperature, sublimation gas is generated from the core body, and the pressure of this gas can apply an internal pressure to the molding material via the cylinder body, so that the pressurizing fluid is purposely used. There is no need to pour it into the body, and since the core body that is the source of the pressurizing gas has a shape similar to the product, that is, the cavity, uniform pressure is applied to the entire molding surface, and the wall thickness is uniform. Good molding can be performed without defects such as voids.

[0022]

Embodiments of the present invention will now be described with reference to the drawings.

In this embodiment, a Ny6-CF round punching blade material obtained by mixing 50% continuous carbon fibers as reinforcing fibers with continuous fibers of nylon resin as a matrix resin and assembling is used as a molding material, Mold a pipe-shaped molded product with a large diameter.

FIG. 1 shows a state before molding in which a molding material is placed in a mold, 1 is a mold made of an aluminum alloy, and the mold 1 is an upper mold 2 having a cavity 3 formed thereon. A lower mold 4 having a cavity 5 formed therein, and a cooling pipe 6 for flowing cooling water and a heater 7 for heating both upper and lower molds 2 and 4.
And are buried.

Reference numeral 8 is a molding material covered on the outside of the tubular body 9, 10 is put in the tubular body 9, and a sublimable core having a shape similar to the product shape defined by the cavities 3 and 5 of the mold 1. It is the body.

A method of arranging the molding material 8 in the mold 1 will be described. First, a silicon rubber tube, which is a rubber material having excellent heat resistance and flexibility, is used as the cylinder 9, and the cylinder 9 is sublimable. The core body 10 is made to follow the shape of the core body 10 while being appropriately sagged.

Thereafter, in the same manner as when the tubular body 9 is covered with the sublimable core body 10, the molding material 8 is made to follow the shape of the sublimable core body 10 on the tubular body 9 and is appropriately sagged and strengthened. The fibers are covered with a thickness of about 3 layers while the orientation direction of the fibers is appropriate.

In this manner, the sublimable core body 10 is first covered with the cylindrical body, and then the molding material 8 is covered on the cylindrical body. Then, both ends of the cylindrical body 9 are fitted into the jig 11, and in this state. The upper and lower molds 2 and 4 are placed in a closed mold 1.

Next, the sublimable core body 10 will be explained. Although there are many sublimable substances as materials for forming the sublimable core body 10, when the molding material is heated, it is formed into a solid state for as long as possible. Since it is preferably maintained, the melting point is preferably 200 ° C. or higher, though it depends on the molding temperature.

Examples of such sublimable substances include aceanthrenequinone, acetamidobenzoic acid, acetophenonecarboxylic acid, acetonaphthenequinone, azonaphthalene,
Aminonaphthol, isovanillic acid, phenylhydrazine hydrochloride, oxyanthraquinone, oxycoumarin, oxytoluic acid, oxypyridine, cantharidin, quinophthalone, chrysoquinone, chlorobenzoic acid, dioxyacetophenone, dioxyanthraquinone and many other substances. .

In order to form a core body similar in shape to a product using such a sublimable substance, of course, a solid material may be machined, but as shown in FIG. 3, it is injection molded or not shown. It is easy according to casting.

FIG. 3 (a) shows a core molding consisting of upper and lower molds 13 and 15 having cavities 14 and 16 in which the molding material and the thickness of the cylindrical body are reduced by 10 to 20% from the product shape. A state in which the sublimable material 17 is injected into the mold 12 is shown, and the sublimable core body 1 is shown in FIG.
The state of removal from the 0 mold is shown.

After the molding material 8 is placed in the mold 1 as described above, the upper and lower molds 2 and 4 are heated by the heater 7 for heating to mold the molding material 8 at 240 ° C. in this embodiment. The mixture is heated to the temperature and held at that temperature for about 1 hour.

Then, as shown in FIG. 2, the tubular body 9 is inflated by the gas generated from the sublimable core body 10, whereby the molding material 8 is pressed toward the cavities 3 and 5.

At this time, as described above, since the molding material 8 and the cylindrical body 9 are arranged in the cavities 3 and 5 in a state of appropriately sagging according to the product shape, the molding material 8
Also, neither the cylindrical body 9 nor the cylindrical body 9 is inflated by force, and since the sublimable core body 10 that is a source of the gas that gives the internal pressure has a shape similar to that of the product, the cylindrical body is formed at the time of molding. Not only does it not rupture, but the molding material 8 follows the cavities 3 and 5 in a uniform state, and a good molded product 18 having a uniform thickness and no voids is formed.

When the molding is completed, the gas in the cylindrical body 9 is discharged from the gas vent holes provided in the jig 11 and the mold 1 (not shown), and at the same time, the cooling water is passed through the cooling pipe 6 to form the upper and lower molds 2. And 4 are cooled, then the mold is opened and the molded product 18 is taken out together with the cylindrical body 9.

When the molding is completed, the sublimable core body 1
Since 0 is reduced by sublimation, the tubular body 9 can be easily pulled out from the molded product 18.

Further, since the cylindrical body 9 is hardly damaged by this molding, it can be used again in the next molding, which is convenient.

[0039]

EFFECTS OF THE INVENTION The present invention has the constitution and operation as described above, and when a hollow FRP product is produced by internal pressure molding, no matter how complicated the shape is, the cylindrical body is applied when the internal pressure is applied. It does not break, the molded product is in a good condition without variations in wall thickness, the orientation of the reinforcing fibers is disturbed, holes are not formed, and voids are not present.

Further, this molding method is extremely simple and does not require a device for injecting compressed air, an inert gas or the like for applying an internal pressure into a mold as in the conventional case, and expands for applying an internal pressure. The cylinder is not damaged during molding, so it can be used repeatedly.

[Brief description of drawings]

[Fig. 1] Arrangement of molding material in a mold,

[Figure 2] Internal pressure molding state of molding material,

FIG. 3 shows a molded state of a sublimable core body.

[Explanation of symbols]

 1 Mold 3,5 Cavity 8 Molding material 9 Cylindrical body 10 Sublimable core body

Claims (1)

[Claims] 1. A molding material made of a fiber reinforced synthetic resin is placed in a molding die by covering a cylinder made of a material having excellent flexibility and heat resistance, and the molding material is heated to a molding temperature, and then the cylinder is molded. In the method for producing a fiber-reinforced synthetic resin molded product that is expanded by applying internal pressure and pressed against the cavity surface, a sublimable core body having a similar shape to the molded product is inserted into the cylinder, and the molding material is heated to the molding temperature. A method for producing a synthetic resin molded article, which comprises applying an internal pressure to a cylinder to expand it by the pressure of a sublimation gas generated from a sublimable core when heated, and molding.