JPH04312811A - Method of skin-integrated foam molding - Google Patents

Abstract

PURPOSE:To prevent the skin of a skin-integrated foam molding from becoming extraordinarily hard. CONSTITUTION:In a method of manufacturing a skin-integrated foam molding by the steps of setting a skin 6 laminated with a slab material in the inner surface of a permeable skin base material into a foaming mold, and foam-curing a foaming resin raw material injected in the inside of the skin in the foaming mold, for respective an upper mold 2 and lower mold 1 of the foaming mold, a foaming mold is used in which penetration holes 9,8,8 communicated from the outside of the mold to the cavity are provided and a communication pipe 3 is connected to these penetration holes. Gases of a skin inner surface side (the side of foam resin 10) moves to the skin outer surface side through the communication pipe 3 and, since the pressure differential on both sides of the skin becomes zero, resin is not impregnated with the slab material, with the result that the skin does not harden at all.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a skin-integrated foam molded product by carrying out foam molding with a skin set in a foam mold, a so-called skin-integrated foam molding method.

0002

2. Description of the Related Art Recently, skin-integrated foam molded products have been used for automobile seats, headrests, etc. Generally, this skin-integrated foam molded product is made by setting the skin in the lower mold of a foam mold, injecting the foamed resin raw material into the inside of the skin, then covering it with the upper mold, and placing the foamed resin raw material inside the closed mold. It is manufactured by foaming and curing.

[0003] When the skin-integrated foam molded product is an automobile seat, polyurethane foam has been conventionally used as the foamed resin, but vinyl chloride sheet, polyvinyl chloride sheet, etc.
In place of synthetic leather and the like, more luxurious fabrics (fiber knitted fabrics or woven fabrics) are increasingly being used.

[0004] When skin-integrated foam molding is performed using the fabric as the skin, since the fabric is breathable, a problem arises in that the foamed resin raw material oozes from the inside (back) side of the skin to the outside (front) side. . For this reason, a skin made by laminating slab material on the inner surface of the fabric is often used. Although the slab material has air permeability, it is sufficient to prevent the foamed resin raw material from reaching the fabric before it is foamed and hardened in the mold.

[0005] When automobile seats are manufactured by skin-integrated foam molding using a skin made by laminating a slab material on the inner surface of a fabric, the foamed resin raw material impregnates the slab material, and the resin is lost and the areas where this impregnation occurs ( Since the resin-impregnated layer (resin-impregnated layer) solidifies, a problem arises in that the surface layer of the automobile seat becomes extremely hard. When the foamed resin raw material is impregnated into the slab material, when the foamed resin raw material expands and expands, filling the mold and further foaming, the pressure on the foamed resin side is relatively lower than the pressure on the slab side (= atmospheric pressure). 5kPa (=0.05kg
/cm2).

[0006] As a method to solve the problem caused by impregnation of the foamed resin raw material into the slab material, methods such as pasting a film on the surface of the slab material or making the slab material thicker to make the impregnated layer less noticeable have been adopted. There is. Furthermore, as disclosed in Japanese Unexamined Patent Publication No. 1-118418, an attempt has been made to reduce impregnation by supplying compressed air from outside the mold to the outer surface of the skin during foam molding.

[0007]

[Problems to be Solved by the Invention] However, each method for dealing with the above-mentioned impregnation problem has problems. First, even if the thickness of the slab material is increased, it is difficult to completely eliminate the feeling of unusual hardness due to the presence of the resin-impregnated layer, and the problem of loss of resin raw material cannot be solved. Next, when applying a film to the slab material, the manufacturing cost will be high, and
Car seats lose their breathability, resulting in seats that tend to get stuffy with sweat. Finally, in the method of sending compressed air from outside the mold to the outer surface of the skin, it is necessary to control the pressure on the outer surface of the skin to be almost the same as the pressure on the inner surface of the skin, which changes from moment to moment, in order to prevent impregnation. This control is very difficult, and if a pressure higher than the pressure of the foamed resin is applied, the foamed cells will collapse and the molded product will be defective.

The present invention has been made to solve the above problem, and the problem to be solved is that even if a fabric whose inner surface is laminated with a slab material is used as a skin, foaming due to pressure difference occurs. It is an object of the present invention to provide a method that prevents undesirable impregnation of a resin raw material into a slab material and obtains a skin-integrated foam molded product without abnormally hardened parts.

[0009]

[Means for Solving the Problems] In the skin-integrated foam molding method of the present invention, a skin in which a slab material is laminated on the inner surface (back side) of an air-permeable skin base material is set in a foam mold, and the inside of the skin is In a method of manufacturing a skin-integrated foam molded product by foaming and curing a foamed resin raw material injected into a foam mold in a foam mold, a through hole communicating with the cavity from outside the mold is provided in each of the upper and lower molds of the foam mold. In addition, the present invention is characterized by using a foaming mold in which communicating pipes are connected to these through holes.

[0010] The number and diameter of the through holes provided in the upper mold and the lower mold are not particularly limited. For example, for each upper and lower mold, φ1 to 2
Only one 0 mm through hole may be provided in the center, or two to several holes may be provided in an appropriate distribution. Note that many urethane foam molds are of the type in which a gas vent hole is provided in the upper mold, and this gas vent hole can be used as the above-mentioned through hole in the upper mold.

[0011] In this specification, the communication pipe refers to a pipe that airtightly connects the spaces of all the through holes provided in the upper mold and the lower mold to constitute one ventilation system, and for example, a flexible pipe such as a rubber hose. It may be made of a material rich in When the communication tube is made of a hard material such as a metal pipe or hard plastic, it is preferably attached removably to the outside of the mold so as not to interfere with opening and closing of the mold. In this case, a pipe connection means is attached to the periphery of the through hole in the mold, and a pipe joint is attached to the middle of the pipe as necessary.
Such pipe connection means and pipe joints may be appropriately selected from known ones, such as so-called G-well type, sleeve type,
It may be bellows type, fitted type, or screwed type.

Further, a regulating valve such as an opening/closing valve or a relief valve may be provided in the middle of the communication pipe. In this case, the more the regulating valve is adjusted so that ventilation can occur freely, the softer the surface of the molded product will be obtained, and the more difficult the ventilation is adjusted, the harder the surface layer of the molded product will be obtained. The skin and foamed resin raw materials to be used, the method of setting the skin, the method of injecting the raw materials, and the foaming curing conditions except for pressure are not particularly limited and may be the same as conventional ones.

[0013]

[Function] Through holes are provided in the upper and lower molds of the foam mold,
When a foaming mold is used in which communication pipes are connected to these through holes outside the mold, gas on the inner surface of the skin moves to the outer surface of the skin through the communication pipes, passes through the skin base material, and reaches the slab material. If the communication pipe is left ventilated, there will be no pressure difference across the skin inside the foam mold, so impregnation of the foam resin raw material into the slab material will not occur. By installing a regulating valve in the middle of the communication pipe and adjusting the ventilation level, the depth of resin impregnation into the slab material can be controlled by the pressure difference on both sides of the skin. Such control of the resin impregnation depth makes it possible to arbitrarily change the softness of the integrally foamed molded product.

[0014]

EXAMPLES Example 1 First, a foam mold used in this example will be explained using FIG. 1. This mold is for manufacturing automobile seats by the skin 6 integral foam molding method, and includes a lower mold 1 and an upper mold 2.
It consists of Through holes 9, 8, 8 are bored in one place in the upper mold 2 and in two places in the lower mold 1, and a communicating pipe 3 is connected to these through holes 9, 8, 8. A regulating valve 5 is installed in the middle of the communication pipe 3, and in this embodiment, the regulating valve 5 is always fully open. Through hole 9 of upper mold 2
The upstream pipe 3a of the communication pipe 3 connected to is detachably connected so as not to interfere with opening and closing of the upper mold 2. A rubber seal 4 can be placed between the contact surfaces (parting parts) of the upper mold 2 and the lower mold 1 as required.

Next, the molding method will be explained. Upper mold 2
The skin 6 is set on the lower mold 1 with it opened. The skin 6 used is a skin base material (fabric) laminated with a slab material. After setting the skin 6 so that the slab material side faces upward, a urethane foaming raw material solution is injected into the inside of the skin 6. Next, a slab piece 11 is attached to the inner surface of the upper mold so as to close the through hole 9 provided in the upper mold 2, and then the upper mold 2 is covered. Immediately after the mold is closed, the upper mold 2 is closed.
The upstream pipe 3a is connected to the through hole. As the foaming/polymerization reaction of the urethane foam raw material liquid progresses, the foamed resin 10 expands and fills the mold, but the urethane foam raw material liquid does not flow out from the through hole because it is blocked by the slab piece 11.

Since the slab piece 11 for preventing urethane outflow allows gas to pass through, the gas on the inner surface of the skin easily enters between the lower mold 1 and the skin 6 through the pipe. The presence of the rubber seal 4 prevents the gas accumulated between the lower mold 1 and the skin 6 from flowing out from the mold parting part. Therefore, no pressure difference occurs on both sides of the skin 6, and the urethane foaming raw material liquid does not impregnate the slab material of the skin 6 due to the pressure on the inner surface of the skin. No abnormal hardness was observed in the full-pad type automobile seat obtained by demolding after foaming and curing.

Example 2 In Example 1, the urethane foaming raw material liquid was injected before the mold was closed, but in this example, the skin was set in the mold, and the urethane foaming raw material liquid was injected with the mold closed. As shown in FIG. 2, the mold is provided with a raw material liquid injection port 7, and after a predetermined amount of urethane foaming raw material liquid is injected through the injection port 7, the lid 12 is closed. A regulating valve 5 provided in the middle of the piping that communicates the through holes of the upper mold 2 and the lower mold 1 opens when the pressure difference between the upstream pipe 3a and the downstream pipe 3b exceeds a certain level. It is set as. Therefore, within the mold, a predetermined pressure difference remains between the inner and outer surfaces of the skin, and the foaming raw material liquid is impregnated to a predetermined depth. In this way, a car seat with appropriate softness and comfort can be obtained.

[0018]

[Effects of the Invention] As can be seen from the above explanation, according to the skin-integrated foam molding method of the present invention, it is possible to prevent the foamed resin raw material from deeply impregnating the skin slab material and making the molded product excessively hard. can. In addition, by installing an adjustment valve in the middle of the communication pipe, you can not only eliminate the resin impregnated layer but also freely change the thickness of the impregnated layer, and freely adjust the hardness of the surface layer of the skin-integrated foam molded product. It becomes possible to do so. Furthermore, compared to known methods that use a separate compressor or the like to send compressed air from the lower mold, the method of the present invention ensures that the pressure of the gas sent to the outer surface of the skin is never higher than the pressure on the inner surface of the skin, resulting in molding such as cell collapse. Do not cause defects.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of an embodiment of the method of the present invention.

FIG. 2 is a cross-sectional view schematically showing an integral foaming mold used in another example.

[Explanation of symbols]

1 Lower mold 2 Upper mold 3 Communication pipe 3a Upstream pipe 3b Downstream pipe 5 Adjustment valve 6 Epidermis 8,9 Through hole

Claims (1)

[Claims] Claim 1: A skin in which a slab material is laminated on the inner surface of a breathable skin base material is set in a foam mold, and a foamed resin raw material injected into the inside of the skin is foamed and hardened in the foam mold. In a method for manufacturing a skin-integrated foam molded product, a foam mold is used in which the upper mold and the lower mold are each provided with through holes that communicate with the cavity from outside the mold, and communicating pipes are connected to these through holes. A skin-integrated foam molding method characterized by: