JPS6142611B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a reaction injection molding apparatus for synthetic resins such as polyurethane, and more particularly to a reaction injection molding apparatus for obtaining polyurethane filled with fillers such as glass fibers.

Reaction Injection Molding
is called RIM, and has recently attracted particular attention as a method for molding polyurethane. The RIM method is a molding method in which two liquid components are usually mixed under pressure and injected into a closed mold, and the liquid component mixture is cured in the mold and taken out. In the case of polyurethane, the liquid component consists of a component whose main component is an isocyanate compound having at least two isocyanate groups (hereinafter referred to as the first component) and at least two
It consists of a component (hereinafter referred to as the second component) whose main component is an active hydrogen compound having active hydrogen,
These are mixed and injected into a mold to form polyurethane within the mold. The RIM method uses not only polyurethane, but also synthetic resins that are cured by mixing two or more liquid components to form a synthetic resin.
For example, it is also used to mold polyester and polyamide.

In this RIM method, various studies have been conducted on molding synthetic resins filled with fillers, particularly reinforced synthetic resins filled with fibrous fillers such as glass fibers as fillers. In the RIM process for polyurethanes, fillers such as glass fibers are premixed with the first component, the second component, or both, and this filler-containing liquid component is mixed and injected in the RIM process. However, a liquid component containing a filler has an extremely high viscosity, which makes mixing and injection difficult. Therefore, in the RIM method using a high viscosity liquid component, it is necessary to use a special method to pressurize the liquid component.
For example, JP-A-53-9854 describes a method in which a highly viscous liquid component is pressurized with a controlled piston pump. However, even with this known method, if the amount of filler increases and the viscosity of the liquid component further increases, pressurization becomes difficult, and a synthetic resin with a high filler content cannot be obtained. A further drawback is that when the filler-containing liquid component is circulated, the surfaces of equipment such as piping and pumps that come into contact with the liquid component become severely abraded, making them more likely to malfunction.

In order to solve these problems, a third component containing a filler is used separately from the first component and the second component, and these three components are mixed and injected.
The RIM method can be considered. The first component and the second component are relatively low viscosity liquid components similar to conventional ones,
The third component is a relatively high viscosity liquid or fluidizable solid component and is not circulated. Therefore, not only can the third component be pressurized easily using a piston pump, etc.
Since the components are not circulated, there is less wear on pipes and equipment. Since the viscosity of the third component may be relatively high, for example, a polyol containing a relatively large amount of glass fibers can be used.

The problem with the RIM method using this third component is the problem of time adjustment for injecting the three components simultaneously. the first component and the second component,
Simultaneous injection can be easily achieved by using a valve piston as shown in the drawings of Japanese Patent Application Laid-Open No. 53-9854. This valve piston can circulate the first and second components respectively when they are not being injected, and when injecting them both are simultaneously injected into the mixing chamber formed in the cylinder at the tip of the valve piston. It is a typical mixing injection device for the RIM method. The third component is mixed with the first component and the second component at any position in the mixing chamber and the runner section leading from the mixing chamber to the mold,
In order not to inhibit the mixing of the first component and the second component, it is preferable that they be mixed at a position somewhat apart from the mixing chamber. If this third component is not injected simultaneously only when the first and second components are injected, the ratio of the third component to the first and second components will become uneven over time. .

As a result of studying various methods of temporally adjusting the injection of the third component with respect to the injection of the first component and the second component, the present inventor found that the valve piston for the injection of the first component and the second component We have found a way to control the injection of the third component with a second valve piston that is linked to the second valve piston.
The present invention is a device for the RIM method in which the injection of the first, second and third components is controlled by means of two interlocked valve pistons. That is,
The present invention provides a first component and a second component that quickly react when mixed with each other to form a synthetic resin, and a mixture of the first component and the second component. In a reaction injection molding device for mixing a third component and injecting the mixture into a mold,
a first valve piston for injecting and mixing the first and second components into a mixing chamber in its retracted position and for circulating each of the first and second components in its advanced position; A runner that connects the chamber and mold,
and a second valve piston coupled to the first valve piston, which in its retracted position injects a third component into the runner and in its advanced position communicates with the third component inlet aperture or the inlet aperture. a second valve piston that closes a passage for a third component. A specific example of the device of the present invention will be shown below to further explain the present invention.

1 to 4 are sectional views showing one example of the device of the present invention, in which FIG. 1 is a sectional view when the two valve pistons are in the forward position, and FIGS. 2 and 3 are in that case. FIG. 2 is a cross-sectional view taken in a direction perpendicular to the cross-sectional view of FIG. 1 through the first valve piston and the second valve piston of FIG. FIG. 4 is a cross-sectional view of FIG. 1 when the valve piston is in the retracted position.

First, FIGS. 1 to 3 will be described in the case where each component is not injected. The first valve piston 1 and the second valve piston 2 are connected to one hydraulic piston 3 and both move in conjunction. The first valve piston has a first groove 6 connecting the inlet hole 4 and the outlet hole 5 of the first component and a second groove 9 connecting the inlet hole 7 and the outlet hole 8 of the second component. and circulate the two components. The flow directions of the two components in this case are indicated by arrows in FIG. The second valve piston 2 is the third
The two inlet holes 10, 11 for the components of are closed.
There is a runner 12 at the tip of the first valve piston 1 and the second valve piston 2, and the second valve piston 2
A partition wall 13 is provided at the runner 12 portion at the tip. The runner 12 is formed between a base part 14 having a valve piston and a lid part 15, and can be separated from the lid part 15 of this base part 14. It is preferable that the base portion 14 and the lid portion 15 are integrated with or connected to each of the two-part mold, and are opened at the same time when the mold is opened. There is a mold on the left side of FIG. 1, and the runner 12 communicates with the inside of this mold. When the first valve piston 1 and the second valve piston 2 move back simultaneously from the state shown in FIG. 1, the state shown in FIG. 4 is reached. The first component and the second component are injected from the respective inlet holes 4 and 7 into a first mixing chamber 16 formed at the tip of the first valve piston 1, mixed, and flow into the runner 12. This mixture then flows into a second mixing chamber 17 formed at the tip of the second valve piston 2 by means of a runner section isolation 13, where it enters the third component inlet hole 1.
It is mixed with the third component injected from 0,11. The mixture of the three components flows through the runner 12 again in the direction indicated by the arrow and enters the mold. When injection is completed, the two valve pistons move forward and return to the state shown in FIG. 1. At this time, a mixture of the first and second components remains on the first valve piston side of the isolation 13 of the runner 12, and a mixture of the three components remains on the mold side and hardens.
The hardened synthetic resin of this runner 12 is
5 is opened and removed, and this is usually taken out at the same time as the molded product is taken out from the mold.

The apparatus of the present invention shown in FIGS. 1 to 4 can be modified in various ways. For example, partitions in the runner section may not be necessary. This partition wall is for improving the mixing of the mixture of the first component and the second component and the third component, and is for improving the mixing of the mixture of the first component and the second component.
The mixture with the third component flows into the second mixing chamber and violently collides with the third component to improve mixing. If there is no partition wall, the mixture of the first component and the second component and the third component will be mixed mainly in the runner section, but if sufficient mixing is achieved in this case, the partition wall is not necessary. Furthermore, injecting the third component from the two inlet holes in a direction in which they collide with each other is also to improve mixing in the second mixing chamber, and if mixing is mainly performed in the runner section, There may be one inlet hole for the third component.
Furthermore, the method of interlocking the valve pistons is not limited. As shown in Fig. 1, in addition to using a hydraulic machine built into the device, for example, there is a method in which the ends of two valve pistons are connected and driven by an external hydraulic machine, etc., and each of the two valve pistons is There is a method in which two cylinders are simultaneously driven by the same hydraulic system.
Furthermore, the second valve piston may not only open and close the outlet hole for the third component, but also open and close the flow path for the third component through which the outlet hole communicates. For example, when the valve piston is in the retracted position, the flow path provided inside the valve piston and the flow path leading to the outlet hole match, allowing the third component to flow, and when the valve piston is in the forward position, the flow paths do not match, causing the flow to flow. It can be stopped. In addition, the number of first valve pistons that control the flow of the third component is not only one, but also two.
There may be more than books. As described above, various modifications can be made as long as the device is provided with the second valve piston that operates in conjunction with the first valve piston and controls the flow of the third component, which is the gist of the present invention.

As mentioned above, the first component and the second component are components that quickly react when mixed with each other to form a synthetic resin. For example, in the case of forming polyurethane, one component contains an isocyanate compound as the main component. The other is a component whose main component is an active hydrogen compound, such as a polyether polyol or a polyester polyol. These include:
Various additives, such as catalysts, stabilizers, blowing agents,
Foam stabilizers, crosslinkers, colorants, etc. can be added, and relatively small amounts of fillers can be added. These first and second components preferably have a relatively low viscosity and are easy to flow compared to the third component.

The third component is preferably a relatively high viscosity component containing a relatively large amount of filler, but may also be a filler-free component, such as a high viscosity active hydrogen compound. Since the filler alone does not flow, it is usually either the first component or the second component, or a first component such as an isocyanate compound or an active hydrogen compound that is different from these or a component thereof, or the first component or the second component. A liquid component that is mixed with and reacts with the second component or a mixture thereof is preferred. However, it may also be a non-reactive liquid such as a lubricating oil or a liquid plasticizer. The third component may also be a liquid or a solid such as a gel that can be fluidized under pressure. A particularly preferred third component is a mixture of a filler and an active hydrogen compound.

Fillers are inorganic or organic solids,
It has a shape such as powder, fiber, flat, granule, etc. In particular, fibrous or flat fillers that improve the physical properties of synthetic resins are preferred. For example, fibrous fillers made of chopped strands or milled fibers such as glass fibers, carbon fibers, and synthetic fibers, and flat fillers such as mica are preferred. Chopped strands of glass fibers and milled fibers are particularly suitable. The content of these fillers in the third component is not particularly limited, but is usually 20 to 90% by weight.

The apparatus of the present invention can mold not only filler-containing synthetic resins but also filler-free synthetic resins.
Polyurethane is the most suitable synthetic resin. For example, molded products such as polyurethane elastomers, hard resins, and foams can be obtained. In particular, synthetic resins filled with glass fibers have excellent physical properties and are suitable for automobile parts.

[Brief explanation of the drawing]

1 to 4 are cross-sectional views showing one example of the device of the present invention. FIG. 1 is a cross-sectional view when two valve pistons are in the forward position, and FIGS. FIG. 2 is a cross-sectional view of the valve piston and the second valve piston, taken in a direction perpendicular to the cross section of FIG. 1; FIG. 4 is a cross-sectional view of FIG. 1 when the valve piston is in the retracted position. DESCRIPTION OF SYMBOLS 1...First valve piston, 2...Second valve piston, 4...First component inlet hole, 7...Second component inlet hole, 11...Third component inlet hole ,1
2... Runner, 13... Partition wall, 16... First mixing chamber, 17... Second mixing chamber.

Claims (1)

[Claims] 1. A first component and a second component that quickly react to form a synthetic resin when mixed with each other, and a mixture of the first component and the second component. In a reaction injection molding device that mixes a third component to be mixed and injects the mixture into a mold, the first component and the second component are injected into a mixing chamber at a retracted position,
a first valve piston that circulates each of the first and second components in its advanced position; a runner that connects the mixing chamber and the mold; and a second valve that is interlocked with the first valve piston. a piston injecting a third component into the runner in its retracted position;
a second valve piston that in its advanced position closes the third component inlet hole or the third component flow path leading to the third component inlet hole. 2 A mixture of the first component and the second component flows from the runner into the second mixing chamber formed at the tip of the second valve piston in its retracted position, is mixed with the third component, and returns to the runner again. 2. The device according to claim 1, wherein a partition wall is provided at the runner portion at the tip of the second valve piston.