JPH03133610A - Method for manufacturing composite articles - Google Patents

Abstract

PURPOSE:To shorten a curing time of a silicone resin material, by a method wherein a silicone resin material for molding thermosetting silicone rubber is preheated directly before injecting by a mold for secondary molding. CONSTITUTION:A preheating chamber 18 is provided at the position of the secondary molding gate part 15 in a mold 6 (stationary) for the secondary molding. The preheating chamber 18 is formed by burying a plurality of pipes 19 flowing a heating medium for temperature adjustment into a circumferential wall of the secondary molding gate port 15. All of the molds 5, 6, 8 and preheating chamber 18 are temperature-controlled by a device where the heating medium such as water or oil is caused to flow through pipes 17 and 19 or a heater is inserted into the pipes 17, 19. Since the reaction of the liquid silicone resin material is inhibited when a reaction inhibitor is added, when the same is preheated up to just before curing in the preheating chamber 18, the same is cured in a short time even with comparatively low mold temperature.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for manufacturing a composite article in which a plastic molded body as a primary molded product and a thermosetting silicone rubber as a secondary molded product are integrated. In particular, the present invention relates to a method for manufacturing a composite article that can be cured and molded in a short time even when the mold temperature during secondary molding is low.

Maenen's composite products include automobile-related resin parts such as cylinder head covers, timing belt covers, radiator cores, headlamp housings, and tail lamp covers, and electrical equipment such as wire noses, waterproof cracks, and inhibitor switches. medical equipment such as dialysis machines and baby bottles, daily necessities such as lunch boxes and various containers, electrical and electronic parts such as waterproof radios, waterproof speakers, rotor trimmers, floppy monitors, water meter covers, etc. Examples include parts.

[Conventional technology]

Conventionally, an apparatus shown in FIG. 8 is known for manufacturing a composite article in which a plastic molded body and a thermosetting silicone rubber are integrated by double injection molding. This consists of a primary molding section 1 consisting of a fixed mold 5 for primary molding fixed to a mold mounting plate 3, and a secondary molding section 2 consisting of a fixed mold 6 for secondary molding fixed to a mold mounting plate 4. and,
It is composed of a rotary mold 8 fixed to a rotary disk 7, and the rotary mold 8 is reversible between the primary molding section 1 and the secondary molding section 2 by the rotation of the rotary disk 7.

In use, first, - after the blow molding mold 5 and the rotary mold 8 are clamped, - the primary molding resin material is injected from the secondary injection bushing 9 through the primary injection gate 10 into the primary molding cavity 11. The cavity 11 is filled with a resin material, and then the resin material is cooled and solidified to form a plastic molded body 12 as a primary molded product.

Next, after opening the mold, the rotary mold 8 is inverted with the plastic molded product main body 12 in the mold, and moved to the primary molded product 2, and then clamped with the fixed mold 6 for secondary molding to produce the secondary molded product. A molding cavity 13 is formed. After that, liquid silicone rubber is injected from the secondary injection spool pusher Li2 into the secondary molding cavity 13 through the secondary molding gate 15, and the secondary molding cavity 13 is filled with the liquid silicone rubber, and then heated and cured. . After the rubber is sufficiently cured, the mold is opened to produce a composite article in which the plastic molded body X2 as a primary molded product and the thermosetting silicone rubber 16 as a secondary molded product are integrated. 17 is a pipe for controlling mold temperature.

[Problem that the invention seeks to solve]

However, in the above-mentioned known technology, it is necessary to lower the mold temperature, especially when the next molded product is a thermoplastic plastic. Otherwise, the next molded product will not be sufficiently cooled and solidified, resulting in deformation. However, if thermosetting liquid silicone rubber is to be cured at such a low temperature, the secondary molding section 2 requires an extremely long curing time compared to the primary molding section 1, resulting in a significant drop in mass productivity. become.

In order to solve this problem, it is possible to increase the curability of the liquid silicone rubber, but if the curability is increased too much, the pot life at room temperature will be extremely short and it will gel during molding.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for manufacturing a composite article that can shorten the curing time even at a low mold temperature and that improves the drawbacks of the above-mentioned known techniques.

[Means for solving problems]

In order to achieve the above object, the present invention provides a method for manufacturing a composite article in which a plastic molded body and a thermosetting silicone rubber are integrated, wherein the plastic molded body is first formed by double injection molding. In a method of injection molding a thermosetting silicone rubber onto the molded product body using a secondary mold after injection molding with a primary mold, the silicone resin used to mold the thermosetting silicone rubber is The material is preheated immediately before being injected into the secondary mold, thereby shortening the curing time of the silicone resin material.

Hereinafter, the present invention will be explained in detail using the accompanying drawings.

FIG. 1 is a cross-sectional view of a specific example of a double injection molding apparatus for carrying out the method of the present invention, and since the parts having the same structure as those in FIG. 8 are as described above, a description thereof will be omitted.

The apparatus shown in FIG. 1 is characterized in that a preheating chamber 18 is provided at the secondary forming gate opening 15 in the secondary forming mold 6 (fixed). Figure 3 shows the secondary molding part 2 in Figure 1.
FIG. 2 is an enlarged cross-sectional view of FIG. 1 , which clearly shows the preheating chamber 18 provided in the secondary mold 6 . Preheating chamber 1
8 is formed by embedding a plurality of pipes 19, 19, .

The temperature of both the mold 5.6.8 and the preheating chamber 18 described above is controlled by means such as flowing a heat medium such as water or oil into the pipe 17.19, or inserting a heater into the pipe 17.19. be done. For example, if the next molded product is a general-purpose plastic such as polyethylene, polypropylene, or ABS, it is controlled at a temperature range of 80 to 120°C, preferably 90 to 110°C.
In the case of engineering plastics such as S and PBT, the temperature is 110 to 150℃,
Preferably, the temperature is controlled within a temperature range of 120 to b'. Further, the temperature of the preheating chamber 18 is 40 to 90°C, preferably 5°C.
It is controlled within the temperature range of 0 to 70°C.

The aforementioned silicone resin material is made by mixing a liquid silicone polymer having an alkenyl group, a silicone polymer having a hydroxysilyl group, and a platinum catalyst, and is adjusted to cure in a very short time by an addition reaction. Further, in consideration of workability, a reaction inhibitor may be added in order to maintain the pot life at room temperature as long as possible. Examples of the inhibitor include acetylene compounds, hydrazines, triazoles, funafins, and mercaptans. When a reaction inhibitor is added to such a liquid silicone resin material, the reaction is suppressed up to 80°C, so if it is preheated in the preheating chamber 18 at a temperature of about 70°C to the point of hardening, it will be relatively stable. Cures quickly even at low mold temperatures.

FIG. 2 is a sectional view of another specific example of the device according to the present invention, which is of a sliding type. In Figure 2, −
The blow molding mold 5 and the secondary molding mold 6 are arranged in parallel, and
These are configured to be slidable by pressing the cylinder 20. In this use, first, a plastic molded body 12 as a primary molded product is injection molded using the blow molding mold 5 in the same manner as shown in FIG. The mold facing the mold 8 is replaced from the primary molding mold 5 to the secondary molding mold 6, and then injection molding is performed in the same manner as in FIG. 1 to produce a composite article according to the present invention. .

In addition, in the present invention, the preheating chamber 1B is located outside the secondary mold 6, as shown in FIG.
2 may be formed by burying the fifth
As shown in the figure, an injection nozzle 24 of an injection base 23 is located outside the secondary molding die 6 and injects the silicone resin material.
and the secondary injection spool bushing 14.

FIG. 6 is a sectional view of still another specific example of the device according to the present invention, which is of the core-back type. This device has a moving core 26 provided with a cylinder 25 for moving the core in a mold 6 for secondary molding. When using this, first, a plastic molded body 12 as a primary molded product is injection molded using the blow molding mold 5 in the same manner as shown in FIG. 1, and then the core moving cylinder 25 is activated. The movable core 26 is moved to form the secondary molding cavity 13, and then injection molding is performed in the same manner as in FIG. A composite article according to the invention integrated with silicone rubber 16 is manufactured. In this case, preheating is performed by providing a plunger pot chamber 21 similar to that shown in FIG. 5 outside the mold. Note that the secondary molding gate opening 15 is connected to both molds 5.
．． 6 is formed on the parting surface 27 of No. 6.

[Effect]

In the present invention, since the silicone resin material is preheated to a state on the verge of hardening immediately before being injected into the secondary mold, the material can be cured in an extremely short curing time even at a relatively low mold temperature. Therefore, a composite article is formed in which the plastic molded body as a primary molded product and the thermosetting silicone rubber as a secondary molded product are integrated in a cycle that is close to or shorter than the molding cycle of the blow molding section. It is possible to mass produce at low production cost.

[Embodiments of the invention]

A molding experiment was conducted using the apparatus shown in the first figure, and a round flange model 28 shown in the seventh figure was formed. The mold clamping force was 160t.

The dimensions of the round flange model 28 are flange outer diameter 110cm,
Inner diameter 68mm, height 35mm, inner thickness 2.5m mark,
Thermosetting silicone rubber 16 has a height of 5.511II11
, is ring-shaped with a width of 3 mm and an inner diameter of 72 mm. The silicone resin material used is ThreeBond 1 made by ThreeBond.
It is 270. In addition, polyethylene resin was used for the plastic molded body 12 as a second molded product.

The mold temperature was 90° C., the preheating chamber temperature was 75° C., the preheating chamber capacity was 5.5 cc, the secondary injection molding capacity was 5.5 cc, the blow molding cycle was 30 seconds, and the secondary molding curing time was 35 seconds.

Furthermore, when molding was carried out under the same conditions as described above using the apparatus shown in Figure 8 without a preheating chamber, the secondary molding curing time was 300 seconds, and the example according to the present invention was much more cured. It can be seen that the time is shortened.

Furthermore, polypropylene, ABS, as blow molding resin;
PBT (CF30%), PA-66 (CF30%
), PA-6 (CF30%), and PC were used, respectively.
In addition to the silicone resin material mentioned above, K E 1940 manufactured by Shin-Etsu Chemical Co., Ltd. was used, and the preheating temperature was set to 6.
When molding was carried out in the same manner as described above except that the temperature was set in the range of 0 to 80°C, the secondary molding curing time was within the range of 20 to 35 seconds.

In FIG. 7, 29 is a primary molded gate, 30 is a secondary molded sprue, 31 is a hole hole, and 32 is a secondary molded fan gate.

〔Effect of the invention〕

As is clear from the above examples, the curing time can be significantly shortened by providing a preheating chamber and preheating the silicone resin material until just before curing before injection. This greatly shortens the entire molding cycle, resulting in excellent mass production and low cost. Furthermore, it has become possible to mass-produce practical level general-purpose plastics such as composite molded PE, PP, and ABS, which were previously only practical with engineering plastics such as PA-6 and PA-66, which have high heat distortion temperatures. . In addition to being used as a sealing material, it can also be used for anti-slip, cushioning, vibration-proofing, sound-proofing, rubber rolls, etc.
Also used for keyboards, rubber switch anode caps, etc.

[Brief explanation of the drawing]

1, 2 and 6 are sectional views of specific examples of injection molding equipment for carrying out the method of the present invention, and FIGS. 3, 4 and 5 are respectively sectional views of the secondary molding section. FIG. 7 is a perspective view of a specific example of the composite article according to the present invention, and FIG. 8 is a sectional view of a known double injection device. 23... Injection group, 24... Injection nozzle, 25.
... Core moving cylinder, 26... Moving core, 2
8...Round flange model.

Claims (4)

[Claims] (1) A method for manufacturing a composite article in which a plastic molded body and a thermosetting silicone rubber are integrated, wherein the plastic molded body is first injection molded in a primary mold by double injection molding, and then, In the method of injection molding thermosetting silicone rubber onto the plastic molded body using a secondary molding mold, a silicone resin material for molding the thermosetting silicone rubber is injected into the secondary molding mold. A method for producing a composite article, characterized in that the silicone resin material is preheated immediately before the curing process, thereby shortening the curing time of the silicone resin material. (2) The method according to claim 1, wherein a preheating section is provided in the secondary mold, and the silicone resin material is preheated by the preheating section. (3) In the method according to claim 1, a preheating section is provided in a plunger pot chamber for injecting the silicone resin material into the secondary mold, whereby the silicone resin material is injected into the secondary mold. A manufacturing method characterized by preheating. (4) In the method according to claim 1, a preheating section is provided between an injection nozzle that injects the silicone resin material and a sprue bush of the secondary mold, whereby the silicone resin material A manufacturing method characterized by preheating.