JPH0425414A - Manufacture of foamed product - Google Patents

Abstract

PURPOSE:To manufacture a foamed product of uniform hardness by providing a communicating component of foamed shape with a number of communicating paths on an open section of an insert, injecting foamed resin through communication components, impregnating the communicating components with foamed resin at the time of foaming and blocking the open section. CONSTITUTION:An insert 1 is disposed in a top force 2 in a manner that an open section 10 is communicated with a runner 20 and foamed resin is in injection from the runner 20 with the pressure of approximately 2kg/cm<2> after closing mold. Then, the foamed resin passed through a number of communicating paths of communicating components 6 and can be injected easily between the insert 1 and a skin material 4. When the give quantity of foamed resin is injected, the injection of foamed resin is discontinues and the foamed resin starts to foam. Reaction is advanced together with foaming to increase molecular weight, and the foamed resin impregnating the communicating components 6 starts to be solidified. Together with the advancement of foaming, therefore, the communicating paths of communicating components 6 are blocked to prevent gas from exhausting from the open section 10 to the runner 20, and cells are prevented from getting broken to make the whole uniform hardness.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to a method for manufacturing foamed products such as automobile instrument panels, armrests, console box lids, etc. The present invention relates to a method of manufacturing a foamed product in which foamed resin is injected through an opening formed by foaming.

[Prior Art] For example, to manufacture an automobile instrument panel, a resin insert and a skin material each formed into a predetermined shape are placed in a split mold, and the insert is inserted from a runner through an opening provided in the insert. Then, inject a specified amount of foamed resin between the insert and the skin material. Then, the skin material is pressed against one mold surface of the split mold by the pressure of foaming the foamed resin, and an instrument panel having a predetermined shape is formed in which the skin material, the insert, and the foam are integrally combined. In the resulting instrument panel, the insert provides overall strength and maintains its shape, the skin material forms the surface design, and the elasticity of the foam provides a soft feel.

Incidentally, the insert is provided with an opening for introducing the foamed resin, and communicates with the split-type runner. However, a problem has occurred in that the foam near the skin material in the portion facing the opening has a different hardness than the surrounding foam. The following two reasons were thought to be the main reasons for this. That is, the resin injected from the runner first collides with the back side of the skin material facing the opening, and then spreads between the insert and the skin material. Here, the foamed resin is generally a two-liquid type, and at the initial stage of injection,
In many cases, the liquids are insufficiently mixed, and therefore, the portion where the mixing is insufficient is concentrated in the portion facing the opening, and the degree of foaming in that portion becomes different from that in other portions. Further, since no insert is present only in the opening portion, it is difficult to hold the foam from the back side, resulting in a problem that the hardness is partially non-uniform.

Therefore, Japanese Unexamined Patent Publication No. 62-253415 discloses a manufacturing method using an insert having an opening divided into a plurality of ribs. According to this manufacturing method, since the foamed resin is injected after first colliding with the ribs, there is an effect that the foamed resin is mixed at the time of collision. The ribs also hold the foam from the back side. Therefore, the resulting foamed product is said to be able to prevent problems such as the hardness of the part facing the opening being different from that of other parts.

[Problems to be Solved by the Invention] However, even with the above manufacturing method, the hardness of the part facing the opening is slightly different from other parts, and further improvement is required in products that require high quality. There is. Therefore, the inventor of the present application conducted further research into the causes of the different hardness. It is also clear that even if a static mixer is installed at the tip of the foaming machine nozzle to ensure mixing, the slight difference in hardness cannot be improved, and that even if the opening of the insert is closed with a hard plug after foaming is completed, there is little improvement. It became. Furthermore, when the opening of the insert was immediately plugged with an injection plug after injecting the foamed resin, they discovered that the hardness became completely uniform. It was discovered that gas leakage from the opening to the runner side causes the cells near the opening to collapse and the foam density to change. Therefore, it was found that the cause of the different hardness was mainly due to the handling of gas.

The present invention was made based on this knowledge, and an object of the present invention is to further prevent different hardness by improving the structure of the opening of the insert.

[Means for Solving the Problems] A method for manufacturing a foamed product of the present invention that solves the above problems includes arranging an insert on one mold surface of a split mold,
In a method of manufacturing a foamed product in which foamed resin is injected between the insert and the other mold surface of a split mold through an opening provided in the insert from a provided runner and integrally foam-molded, the opening of the insert is It has a foam-like communication member with a large number of communication paths, and the foamed resin is injected through the communication member, and when foaming, the foamed resin impregnates the communication member and closes the opening.

The most important feature of the present invention is the provision of a foam-like communication member in the opening of the insert. This communication member has a large number of communication passages, and when foamed resin is injected, the foamed resin is easily injected through the communication passages. Further, during foaming, as the reaction progresses, the foamed resin impregnated into the communication member solidifies and closes the opening. Therefore, gas is prevented from flowing toward the runner from the opening, and the pressure of foaming is uniformly transmitted throughout, thereby reliably preventing different hardness. Further, after the foaming is completed, the communication member impregnated with the foamed resin and solidified holds the foam from the back side of the opening.

Such communicating members include foams with open cells,
Examples include nonwoven fabrics, woven fabrics, and net-like bodies, and the size of the communicating passages can be variously selected depending on the viscosity of the foamed resin, injection pressure, etc. In the case of molding with general urethane foam, the diameter of the communicating path is preferably 0.5 to 10 mm, particularly preferably 1 to 6 mm. If it is smaller than 0.5 mm, the injection pressure will become extremely high, which is not a good idea. Moreover, if it is larger than 10 mm, it will be difficult to impregnate the urethane foam, and gas leakage will occur. Further, it is desirable that the thickness of the communication member be 2 mm or more (particularly preferably 3 mm or more) within the product wall thickness. If it becomes too thin, it will be difficult to develop the effect. Although the insert and the communication member are integrally fixed, bonding, mechanical fixing, or integral molding can be used as a fixing method.

The insert material can be the same as the conventional one, and the split mold can also be the same as the conventional one. It is also preferable to place a soft skin material such as vinyl chloride resin on the other mold surface of the split mold and integrally mold it together with the insert.

[Operation] In the manufacturing method of the present invention, first, an insert is placed on one mold surface of a split mold. At this time, the runner and the opening of the insert are arranged so as to communicate with each other.

Then, the split mold is clamped, and foamed resin is injected from the runner through the opening between the insert and the other mold surface of the split mold. At this time, the foamed resin is easily injected through the communication path of the communication member.

Thereafter, it is maintained at a predetermined temperature for a predetermined time. Then, the foamed resin foams and fills the inside of the cavity, and also impregnates the communication member and solidifies. Therefore, since the opening is closed by the communicating member impregnated with the foamed resin, gas escape is prevented, the foaming pressure becomes uniform throughout, and cell soaking is prevented.

When the split mold is opened after foaming is completed, the insert and foam are integrally bonded, resulting in a foamed product with uniform hardness.

[Effects of the Invention] That is, according to the method for manufacturing a foamed product of the present invention, opening and closing of the opening can be controlled by simply performing the foaming resin injection process and foaming process as in the past, and gas handling from the opening to the runner can be controlled. Injuries are prevented, cells are prevented from soaking, and the foaming pressure is uniform throughout. Therefore, a foamed product with uniform hardness can be easily and reliably manufactured with the same number of steps as in the conventional method.

[Example] Hereinafter, this will be explained in detail using examples.

In this example, the present invention is applied to manufacturing an automobile instrument panel. That is, as shown in FIG. 1, in this manufacturing method, a plate-shaped resin insert 1 previously formed into a predetermined shape is placed along an upper mold 2, and a vinyl chloride resin is placed on the mold surface of a lower mold 3. A made skin material 4 is placed. Next, after clamping the upper mold 2 and the lower mold 3, foamed urethane resin is injected between the insert 1 and the skin material 4 from the runner 20 of the upper mold 2 through the opening 10 provided in the insert 1. Then, the skin material 4 is pressed along the mold surface of the lower mold 3 by the foaming pressure of the foamed urethane resin, and an instrument panel in which the insert 1, the foam 5, and the skin material 4 are laminated and joined together is manufactured. Ru.

FIGS. 2 to 4 show the insert 1 used in this example. The insert 1 is made of hard resin such as PP or ABS and has a thickness of 3 mm, and has a circular opening 10 with a diameter of 20 mm at a position where it contacts the runner 20. A communication member 6 is fixed to the opening end surface of the opening 10 on the side facing the skin material 4 by adhesive. This communication member 6 is formed from a skeletal form ([Everlight Scotto HR-08J manufactured by Brideston Co., Ltd., number of cells: 8/25 mm] that is generally used as a skeletal material for impregnation, and has a size of 40 mm x 4 Q mm x 5 mm. .

The insert 1 is placed in the upper mold 2 so that the opening 10 communicates with the runner 20, and after the mold is clamped, foamed resin is injected from the runner 20 at a pressure of 2 kg/cm2. Then, the foamed resin is easily transferred and injected between the insert 1 and the skin material 4 through the many communication passages of the communication member 6.

When a predetermined amount of foamed resin is injected, the injection of the foamed resin is stopped and the foamed resin begins to foam. As the foaming progresses, the reaction progresses, the molecular weight increases, and the foamed resin impregnated into the communication member 6 begins to solidify. Therefore, as the foaming progresses, the communication path of the communication member 6 is closed, and gas is prevented from escaping from the opening 10 to the runner 20, thereby preventing the cells from collapsing and making the foaming pressure uniform throughout. Further, the communication member 6 impregnated with foamed resin supports and reinforces the foamed body 5 from the back side at the position of the opening 10. Therefore, the opening 10
The portion of the foam 5 that faces the other portions has the same hardness as the other portions, and the entire portion has a uniform hardness.

[Brief explanation of the drawing]

Figures 1 to 3 relate to a method for manufacturing a foamed product according to an embodiment of the present invention, in which Figure 1 is a sectional view of the mold at the end of molding, and Figure 2 is a perspective view of the main parts of the insert used. , FIG. 3 is a sectional view taken along line AA in FIG. 2. 1... Insert 2... Upper mold 3... Lower mold 4... Skin material 5... Foam
6...Communication member 10...Opening part 20
...Runner patent applicant Tokai Kasei Kogyo Co., Ltd. agent Patent attorney Hiroshi Okawa Figure 1 Figure 3

Claims (1)

[Claims] (1) An insert is placed on one mold surface of the split mold, and a runner provided on one of the split molds connects the insert with the other mold surface of the split mold through an opening provided in the insert. In a method for manufacturing a foamed product in which a foamed resin is injected between the inserts and integrally foamed, the opening of the insert has a foam-like communication member having a large number of communication paths, and the foamed resin is injected through the communication member. A method for manufacturing a foamed product, characterized in that during foaming, the foamed resin impregnates the communication member and closes the opening.