JPH0788023B2 - Mold form molding method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention is a reaction injection molding method used in the field of manufacturing mold foams for interior products such as automobile seat cushions, motorcycle seat cushions, head dresses, and furniture. (Hereinafter referred to as RiM method) and a so-called high speed cure-HR method.

[Conventional technology]

As shown in Fig. 6, the conventional mold forming method using the RiM method uses the hinge (3) as a fulcrum to support the upper die (1).
The flange surface (7) and the rubbed portion are brought into immediate contact with each other to close the mold (referred to as the one-step mold clamping method), and then the undiluted solution is injected by the runner and the film gate. The air and gas in the cavity after the stock solution is injected can be removed by the gas vent holes (hereinafter referred to as vent holes) shown in FIG.
(6) and / or only through a gas vent groove (hereinafter referred to as a vent groove) provided in the rubbed portion (5).

[Problems to be solved by the invention]

In the mold-form molding method using the RiM method, improving the yield (quality product yield) and reducing the injection loss of the undiluted solution are important requirements for reducing the product cost.

Conventionally, in the RiM method, 100% of air and gas in the cavity must be removed from the vent hole and / or the vent groove in order to inject the raw material after the mold is clamped. If the removal of air and gas is incomplete, the reaction of the undiluted solution proceeds and the air and gas remain in the cavity during the process of growing into a foam, which causes punctures from the vent hole and / or vent groove. It is less likely to occur and causes a drawback of collapsing (disintegration) in the mold form product.
Therefore, the product is almost defective. In addition, if the air and gas in the cavity are insufficiently removed, the internal pressure of the cavity will increase and the flow of the undiluted reactant will be impeded, causing problems such as lack of wall thickness on the vertical line (Fig. 6 (8)) and the back surface. Is likely to occur. Therefore, in the past, it was attempted to increase or enlarge the vent holes and vent grooves in order to completely eliminate the air and gas in the cavity, but in that case the raw material loss due to punctures increased and the product weight was reduced. The injection volume needed to be increased to match.

The present invention, by smoothly excluding air and gas in the mold cavity, to uniformly fill the undiluted reaction product into the mold, collapses, significantly reduce the occurrence of wall thickness, etc.,
At the same time, the aim is to reduce the material loss due to the injection amount and punctures as much as possible by making the vent holes and / or the vent grooves as small as possible and reducing the number, improving the yield and reducing the product cost. Is.

[Means for solving problems]

The present invention, in the mold form molding method by RiM method, using the mold clamping device by the pressing method or the simple pressing method, even after the undiluted solution injection between the upper mold and the lower mold evenly 1 mm or more, 100 mm or less It provides a mold form molding method in which the mold is clamped after holding the clearance for a certain period of time, and the injection of the stock solution into the mold is carried out directly from the high-pressure injection head via a single point injection method or a distributor for the injection of the stock solution. The injection method of is adopted. Furthermore, it is preferable that the mold clamping device of the present invention has a mold tilting mechanism (FIG. 4ABC), and the mold clamping device is tilted before or after starting the injection of the undiluted solution into the mold, or after the completion of the injection.

In order to maintain a clearance of 1 mm or more and 100 mm or less between both flange surfaces of the upper mold and the lower mold of the mold clamping device for a certain period of time in the present invention, for example, a lower mold lift-up mechanism is provided as shown in FIG. At the time of closing the upper mold of the mold clamping device, there is a uniform clearance [A (11) in FIG. 1] between the flange surfaces of the upper mold and the lower mold, and the mold is not completely clamped.
In this case, the same applies to a mechanism for fixing the lower mold and lowering the upper mold. The clearance needs to be 1 mm or more and 100 mm or less, preferably 2 mm or more and 10 mm or less. In this case, air and gas in the cavity can be sufficiently removed at the initial stage.

If the clearance is less than 1 mm, the effect of eliminating air and gas is small, and if the clearance exceeds 100 mm, it becomes difficult to design and manufacture the mold clamping device, and the manufacturing cost of the mold clamping device of the present invention is high. Yes, both cannot be adopted in the present invention.

Further, if the clearances are not uniform, the generation of air and gas cannot be balanced, resulting in defects such as collapse and lack of thickness.

It is necessary to perform mold clamping at the timing when the undiluted reaction product does not overflow from the parting line [Fig. 1 (8)], and the clearance retention time is determined by the size, shape and injection conditions of the product. It is possible to set the time freely according to them. Elimination of air and gas after mold clamping is sufficiently effective with a small number of vent holes and / or vent grooves. In some cases, vent holes or grooves may not be needed. Further, in the present invention, it is necessary to adopt the one-point injection method directly below the high-pressure injection head as shown in FIG. 2 or the injection method using a concentrate injection distributor as shown in FIG. 3 for the injection of the stock solution. In the mold-form molding method of the present invention, since there is a clearance also in the mating portion of the mold during the injection of the undiluted solution, the injection by the runner and the film gate as in the conventional method is impossible.

The press type or simple press type mold clamping device used in the present invention preferably has a mold inclining mechanism. For example, as shown in FIGS. 4A, 4B, and 4C, the mold is actuated and tilted so that the undiluted solution is uniformly dispersed in the lower mold, and the defects such as air pockets are remarkably reduced.

The present invention is also suitable for a mold form molding method using a so-called high-speed cure HR method in which a high-pressure foaming machine is used and a reaction injection molding is performed in a temperature-adjustable mold with a variable angle having a good friction for a high-speed reaction mixture. Used for.

〔Example〕

The high-pressure foaming machine used in the present invention is a high-pressure foaming machine manufactured by Klaus Mathuai, and the injection conditions are discharge rate, 500 g / sec, injection pressure, polyol 100 Kg / cm ² , isocyanate 80 Kg / cm ² ,
Liquid temperature is 28 ℃ for both polyol and isocyanate, mold temperature
60 ° C, curing time is 2 minutes. The cross-sectional area of the cleaning piston of the high-pressure injection head is 16 mm. Examples,
The molding conditions of the comparative example are shown in Table 1.

Examples 1 to 4 By using the high speed cure-HR method, the seat cushion for an automobile shown in FIG. 5 is used with a mold clamping device having a lower mold lift up mechanism as shown in FIGS. 1A and 1B. By selecting the single point injection method as shown in Fig. 2 and by the steps shown in Fig. 4, A, B, and C, the initial mold angle is -25 degrees, and the mold tilt start time is 1 second after the start of reaction injection. The mold angle was +35 degrees when the tilting was completed, the tilting time was 4 seconds, and the stock solution injection position was molded under the conditions shown in Table 1 in Fig. 5 (15).

The target proper product weight is 1200g.

Comparative Example 1 Molded in Example 1 by the one-step mold clamping method.

Comparative Example 2 In Comparative Example 1, the injection amount was changed as in the conditions shown in Table 1 for molding.

Comparative Examples 3 to 4 In Comparative Example 1, the vent hole was molded under the conditions shown in Table 1.

Comparative Example 5 In Comparative Example 4, the injection amount was changed as in the conditions in Table 1 for molding.

Comparative Example 6 In Example 1, molding was performed by changing the clearance between the upper and lower mold flanges as in the conditions of Table 1.

Table 2 shows the results of mold form molding in Examples and Comparative Examples.

As is apparent from Table 2, according to the present invention, the mold formability is improved, the yield is improved, the raw material loss rate is reduced, the drawbacks of the prior art are eliminated, and the dramatic improvement of the prior art is achieved. Was done.

〔The invention's effect〕

 The effects of the present invention are summarized as follows.

(A) In the conventional technology, the exclusion of air and gas in the cavity is insufficient, and the pressure inside the cavity increases, so that the flow of the undiluted reactant in the mold is obstructed, and the parting line and the back surface of the product are not However, in the present invention, after injection of the undiluted solution, air and gas in the cavity are smoothly and sufficiently removed in the process in which the reaction progresses and grows to form a defect such as collapse and lack of meat. Does not occur.

(B) In the prior art, a large number of vent holes and / or vent grooves are required to remove the air and gas in the cavity, but even in that case, the internal pressure of the cavity is high and the loss of undiluted solution as banks occurs. It was necessary to increase the injection amount in order to secure a fairly large and appropriate product weight. However, in the present invention, air and gas are sufficiently removed at the initial stage, so vent holes and vent grooves are conventionally used. The number of injections and the loss rate of raw materials can be greatly reduced because the number of punctures is uniform and stable, and the stable product weight is secured.

(C) In the present invention, the internal pressure of the cavity is suppressed to be small, so that the load on the mold and the mold clamping device is reduced and the durability is improved.

(D) Since the mold clamping device used in the present invention is a press system or a simple press system, there is no unbalanced load on the rubbed portion as seen in the conventional one-stage mold clamping method, and the durability of the mold is significantly improved. To do.

As described above, according to the present invention, dramatic improvement in moldability and yield, and significant reduction of raw material loss have been achieved.

[Brief description of drawings]

FIGS. 1A and 1B show an embodiment of a mold clamping device of the pressing method or the simple pressing method used in the present invention. A is a mold clamping completion diagram when a clearance is provided and B is a lower mold lift-up, Two
FIG. 3 is a diagram of an embodiment of the single-point injection method used in the present invention, FIG. 3 is a mounting view of a distributor for injecting a stock solution used in the present invention, FIG. 4A,
B and C are diagrams showing a working process using a mold clamping device having a mold inclining device according to an embodiment of the present invention, in which A indicates injection of a stock solution, B indicates inclination completion, and C indicates mold clamping completion. 5A and 5B are views showing an example of the mold form product manufactured according to the present invention, where A is a front view and B is a side view. FIG. 6 shows a view of a mold clamping device in the prior art. 1 ... Upper mold, 2 ... Lower mold 3 ... Hinge, 4 ... High-pressure injection head 5 ... Lattling part, 6 ... Vent hole 7 ... Flange, 8 ... Parting line 9 ... Upper mold mounting Frame, 10 …… Lower mold mounting frame 11 …… Clearance, 12 …… Inlet tube 13 …… Cleaning piston, 14 …… Distributor for undiluted solution injection 15 …… Undiluted solution injection position

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical display location B29C 45/64 7365-4F // B29K 75:00 (72) Inventor Junji Yamamoto Kakogawa, Kakogawa, Hyogo Prefecture 374-3, Ono Machi (72) Masahiro Ushio 2-9-10 Kaminakajo, Ibaraki-shi, Osaka (72) Inventor Isamu Nishida 28-11 Tamase-cho, Ibaraki-shi, Osaka

Claims (4)

[Claims] 1. A mold form molding method using a reaction injection molding method (hereinafter referred to as RiM method), which uses a mold clamping device by a pressing method or a simple pressing method, and the flange surfaces of the upper mold and the lower mold even after injection of the undiluted solution. A mold-form molding method characterized in that a clearance of 1 mm or more and 100 mm or less is uniformly held between the molds and then the mold is clamped. 2. A molding according to claim 1, which is based on a so-called high-speed cure HR method in which a high-pressure foaming machine is used to perform reaction injection molding into a temperature-adjustable mold having a variable angle and having a good fit for high-speed reaction compounding. Forming method. 3. The RiM method, wherein the injection of the undiluted solution into the mold is a direct injection type one-point injection method from a high-pressure injection head or an injection method through a distributor for undiluted solution injection.
Item 3. The mold form molding method according to Item 2 or Item 2. 4. The method according to claim 1, 2, 3 or 4, wherein the mold clamping device of the press system or the simple press system performs the molding by arbitrarily tilting the mold by a mold tilting mechanism. Mold form molding method.