JPH0558369B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for producing a film-like molded product having a foamed resin layer, which is used as a skin material for automobile interior materials, furniture, and other products.

(Prior Art) Conventionally, the following powder slush molding method has been used as a method for producing a film-like molded product having the above-mentioned foamed resin layer.

First, as shown in FIG. 4, a powdered resin 14 containing a foaming material is charged into a slush mold 12 having an opening 10. Then, by heat transfer from the mold surface 13 of the preheated slush mold 12, the powdered resin 14 is welded to a predetermined thickness and adhered to the mold surface, and then the slush mold 12 is turned over. Then, the excess powder resin 14 that did not adhere to the mold surface is discharged from the slush mold 12. Thereafter, the powdered resin layer on the mold surface is further heated to melt the powdered resin and decompose the foaming agent to cause foaming, thereby obtaining a film-like molded product having a foamed resin layer.

At that time, the heating of the powder resin layer attached to the mold surface is
This is accomplished by housing the slush mold in a heating oven, by passing a heat medium through a circulating pipe connected to the slush mold, or by immersing the slush mold in a fluidized bed of heat medium.

In addition, in order to manufacture a film-like molded product formed by laminating a non-foamed resin layer and a foamed resin layer, it is necessary to
As described in Japanese Patent No. 101014, first, a powdered resin containing no foaming agent is put into a slush mold, adhered to the mold surface, and heated and melted to form a non-foamed resin layer. Thereafter, in the same manner as described above, a powdered resin containing a foaming agent is put into a slush mold and melted and foamed by heating to form a foamed resin layer on the non-foamed resin layer.

The film-like molded product thus produced is then placed in a foaming mold, and a liquid foaming raw material such as polyurethane foam is injected into the inner surface of the film-like molded product to perform integral foam molding. As a result, a desired foam molded product, such as a pillar garnish, is formed in which the foam is integrated with the inner surface of the film-like molded product.

(Problem to be Solved by the Invention) By the way, when the film-like molded product is used as a skin material for a pillar garnish or door trim in an automobile, the end of the film-like molded product is not shaped into a rolled-up shape. Most of them are. The molding of a film-like molded product with such a rolled-up shape is
The same process as described above is carried out using the slush mold 12 shown in FIG. 4, that is, the slush mold 12 having an undercut 18 for the opening 10. At this time, if the slush mold is simply turned over, excess powder resin that did not adhere to the mold surface will accumulate inside the undercut 18 and will be difficult to discharge from the slush mold. is used to blow off the powdered resin that has accumulated in the undercut area. Note that the film-like molded product obtained in this way is originally
Although the part below the part is the product part, in order to obtain a homogeneous film-like molded product, the slush mold 12
An extension surface 13a that expands following the opening edge is provided,
Powdered resin is attached to the mold surface and the extended surface 13a, and a large film-like molded article is formed by successively heating and melting the resin. Then, the extension surface 1
3a (15 in Figure 5)
a) As shown in FIG. 5, the lower mold 16 and the upper mold 17
The film-like molded product 15 is held in place during foam molding. After this foam molding, the film extension part 15a of the film-like molded product is cut off from A-A along with the protrusion (burrs) of the foam, and the film-like molded product molded by the mold surface 13 of the slush mold becomes the skin. Become.

However, in the above manufacturing method, even if the powder resin adheres uniformly to the mold surface, the inside of the rolled-up part (undercut part 18 of the mold surface) has a large curvature, so the powder resin on the inside of the rolled-up part foams toward the center of curvature, and swells up to fill the inside of the rolled-up portion. Therefore, the thickness of the rolled-up portion becomes larger than other portions, and sometimes the narrow portion leading to the undercut portion may be closed. As a result, even if the film-like molded product is placed in a foam mold, a polyurethane foaming raw material is injected, and a pillar garnish, etc. is integrally foam-molded, the polyurethane foam may not be filled into the wrapped portion. However, because the film at the rolled-up part is thick, the hardness of the product may be different from other parts.

On the other hand, in order to promote the melting and foaming of the powder resin layer attached to the mold surface, a method has been proposed in which hot air is applied to the surface of the powder resin layer, such as in Japanese Patent Application Laid-Open No. 62-7517. Although the surface of the resin layer that is in contact with the resin layer is heated to a predetermined temperature, the further back from the surface (toward the mold surface side) the less heat is transmitted and the resin layer becomes more difficult to heat. Moreover, since the foaming of the powder resin layer increases the heat insulating properties of the resin layer, heat is no longer transmitted to the inside. In addition, when producing a film-like molded product in which a non-foamed resin layer and a foamed resin layer are laminated as described above, the non-foamed resin layer is interposed between the powder resin layer containing a foaming agent and the mold surface. Therefore, the inside of the powder resin layer containing the foaming agent is in a state where it is difficult to be heated even from the mold surface.

As a result, the foamed state of the foamed resin layer becomes non-uniform, and there is a problem that a film-like molded product having a good soft feel cannot be obtained.

Therefore, the present invention aims to provide a method for manufacturing a film-like molded product having a foamed resin layer that solves the above-mentioned problems.

(Means for solving problems) The gist of this invention is as follows.

1 Powdered resin containing a foaming agent is put into a slush molding mold that has an undercut for the opening, and the powdered resin layer is heated from both the mold surface and the surface of the powdered resin layer to melt the powdered resin. At the same time, in the method of manufacturing a film molded product having a foamed resin layer by decomposing the foaming agent, by using far infrared rays as the heating means from the surface of the powdered resin layer, the protrusions constituting the undercut are removed at the undercut portion. A method for manufacturing a film-like molded product having a foamed resin layer, characterized in that the molding is performed while substantially shielding far infrared rays in the undercut and suppressing foaming of powdered resin within the undercut.

2. Film-like molding having a foamed resin layer according to 1 above, characterized in that the undercut part of the mold is kept at a lower temperature than other parts to reduce the amount of powdered resin adhering to the undercut part in advance. method of manufacturing the product.

3. The method for manufacturing a film-like molded product having a foamed resin layer according to 1 or 2 above, characterized in that far-infrared heating is performed from outside the opening of the mold.

(Function) The layer of powdered resin that is put into the slush mold and adheres to the slush mold is heated not only by the mold surface but also by the far infrared rays irradiated onto the surface, melting it and decomposing the foaming agent. The foam is then foamed to form a foamed resin layer. At this time, in the undercut part of the slush mold, the far infrared rays that propagate toward the inside of the undercut are almost completely blocked by the protrusions that make up the undercut part.
Only a small amount of far infrared rays hits the powdered resin within the undercut portion. As a result, the powdered resin in the undercut portion is heated at a lower temperature than the powdered resin in other portions, and foaming is suppressed. Thereby, the thickness of the foamed resin layer formed within the undercut portion can be prevented from becoming thicker than the thickness of other portions.

In addition, by keeping the undercut at a lower temperature than other parts and reducing the amount of powdered resin adhering to the undercut in advance, the thickness of the foamed resin layer within the undercut can be more effectively reduced. This can be controlled and the increase in thickness in the area can be suppressed more reliably.

Furthermore, far-infrared rays have the property of heating an irradiated object not only from the irradiated surface but also from within as it penetrates into the object. Therefore, the powder resin layer heated by far-infrared ray irradiation foams uniformly inside the powder resin layer (on the mold surface side), and a film-like molded product having a foamed resin layer with a uniform expansion ratio is obtained. Moreover, since the foam is formed by heating from the inside and outside, the surface of the foamed resin layer becomes a uniform surface.

(Example) The present invention will be described below using as an example a film-like molded product in which a non-foamed resin layer and a foamed resin layer are laminated.

The powdered resin that forms the non-foamed resin layer (hereinafter referred to as the first powdered resin) is usually a powdered thermoplastic resin such as vinyl chloride resin and auxiliaries such as stabilizers, plasticizers, and flame retardants. is used.

Further, the powdered resin (referred to as the second powdered resin) forming the foamed resin layer is the first powdered resin composition containing a foaming agent. The blowing agent is one that is decomposed by heat, and for example, an azo compound such as azodicarbonamide, a sulfonyl hydrazide compound such as benzenesulfonyl hydrazide, or other organic or inorganic blowing agent is used.

FIG. 1 is a sectional view of a slush mold 20 used in one embodiment of the present invention.

This slush mold 20 has a protrusion 24 forming an undercut 22 with respect to an opening 21 on the inner surface of the mold, and a pipe 26 for circulating a heat medium for heating the mold surface on the outer surface of the mold. It is.

First, the opening 21 of the slush mold 20
is closed with the bucket 28 housed in the first powdered resin 30, and the slush mold 20 and the bucket 28 are rotated while the mold surface is preheated to 140 to 250°C with heated oil passing through the circulation pipe 26 on the outside of the mold. , the first powdered resin 30 in the bucket is attached to the mold surface of the slush mold 20. During the rotation, each time the slush mold 20 comes to the upper position, vibration is applied to the slush mold 20 using an air knocker (not shown), etc., and excess powder resin 30 not attached to the mold surface is slush molded. Type 20
to uniformly adhere the powdered resin to the mold surface. Removal of excess powdered resin by this air knocker is more efficient than conventional removal by blowing air, and is also superior in terms of maintenance.

After continuing to rotate until a predetermined amount of the first powder resin adheres to the mold surface, the excess powder resin is poured into a bucket with the opening 21 of the slush mold facing downward.
8, and then the bucket 28 is removed from the slush mold 20, and the first powder resin adhering to the mold surface is further heated by the circulation of the heated oil. As a result, the first powdered resin adhering to the mold surface is melted, and a non-foamed resin layer is formed on the mold surface.

Note that the above steps are not necessary when manufacturing a film-like molded product consisting only of a foamed resin layer.

Next, the opening 21 of the slush mold 20 is closed with a bucket containing a second powdered resin containing a foaming agent (not shown). A predetermined amount of the second powder resin is adhered to the surface of the non-foamed resin layer by the heat retained in the foamed resin layer. Note that when there is no non-foamed resin layer, the second powder resin adheres to the mold surface due to the heat of the mold surface. After the second powdered resin that has not adhered is stored in the bucket, the bucket is removed from the slush mold. During this time, the temperature of the slush mold is maintained below the decomposition temperature of the blowing agent.

Next, as shown in FIG. 2, a far-infrared heater 31 is placed outside and above the opening 21 of the slush mold, and the surface of the second powder resin layer 32 is irradiated with far-infrared rays 34 to heat the second powder resin. Layer 32 is heated from the surface. At the same time, the second powder resin layer 32 is heated from the mold surface via the non-foamed resin layer 33 by the heated oil passing through the circulation pipe. Note that if there is no non-foamed resin layer, the second powder resin layer 32 will be heated directly from the mold surface. By this,
The second powdered resin melts and the foaming agent decomposes and foams to form a foamed resin layer. The heating temperature is usually about 160 to 250°C. At this time, the inside of the undercut 22 of the slush mold 20 is shaded by the projection 24 forming the undercut, so the far infrared rays 34 are almost blocked by the projection 24, and the second powder inside the undercut 22 is hidden. It is in a state that it hardly reaches the surface of the resin layer 32.
Therefore, the second powder resin adhering to the undercut 22 is heated to a lower degree than the second powder resin adhering to other parts, and foaming is suppressed. As a result, undercut 22
It is possible to prevent the thickness of the foamed resin layer from increasing within the section, and it is possible to obtain a film-like molded product with a uniform thickness.

Furthermore, when attaching the powdered resin containing the foaming agent (second powdered resin), the temperature of the oil flowing through the circulation pipe 26a located outside the undercut portion 22 is adjusted to the temperature of the oil flowing through the other circulation pipes. By keeping the undercut portion 22 at a lower temperature than the other portions, the amount of powder resin deposited on the undercut portion can be made smaller than the amount on other portions. Thereby, it is possible to more effectively suppress an increase in the thickness of the foamed resin layer at the undercut portion.

Note that the means for heating the mold surface is not limited to the circulation of the heating oil, but may be other known means.

The film-like molded product thus formed is removed from the slush mold after cooling.

FIG. 3 is a partial sectional view of a film-like molded product 36 obtained in the above example. The molded product 36 is
A foamed resin layer 38 is laminated on the back side of a specific foamed resin layer 33, and has rolled-up portions 39 formed by the undercut portion of the slush mold at both ends with approximately the same thickness as other portions. be. Further, the foamed resin layer 38 is foamed almost uniformly, and has a skin layer 38a on its surface. The skin layer 38a is first formed by heating the powdered resin layer containing a foaming agent from the inside with far infrared rays as described above.

(Effects) Since the present invention has the above-described configuration, it was possible to obtain a film-like molded product in which the thickness of the rolled-up portion, etc., which becomes an undercut, is not thicker than other portions. As a result, when the film-like molded product is placed in a foaming mold and polyurethane foaming raw material is injected and integrally molded, it is difficult to fully infiltrate the polyurethane foaming raw material into narrow areas such as the rolled-up part. This made it possible to produce products with no difference in hardness.

In addition, by heating the layer of powdered resin containing a foaming agent from the inside and outside using far infrared rays, it is possible to form a foamed resin layer with a uniform foaming state, resulting in a film-like molded product with a better soft feel. There are also benefits that can be gained.

Furthermore, since the surface of the foamed resin layer of a film-like molded product is a uniform surface layer, when a foamed molded product is integrally molded using the film-like molded product, the foam made from the liquid foam raw material has a uniform surface layer. It also has the advantage that the soft feel of the film-like molded product that becomes the skin is not impaired.

[Brief explanation of drawings]

FIGS. 1 and 2 are cross-sectional views explaining one embodiment of the present invention, FIG. 3 is a partial cross-sectional view of a film-like molded product having a foamed resin layer obtained by implementing the present invention, and FIG. FIG. 5 is a cross-sectional view illustrating the powder slush molding method. FIG. 5 is a cross-sectional view when a film-like molded product having a foamed resin layer is placed in a foam mold and foam-molded. 20... slush mold, 21... opening,
22...Undercut portion, 24...Protrusion, 34
...far infrared rays.

Claims (1)

[Claims] 1. Powdered resin containing a foaming agent is placed in a slush mold having an undercut for the opening, and the powdered resin layer is heated from both the mold surface and the surface of the powdered resin layer. In the method of manufacturing a film-like molded product having a foamed resin layer by melting the powdered resin and decomposing the foaming agent, the undercut portion is A method for producing a film-like molded product having a foamed resin layer, characterized in that the protrusions constituting the undercut substantially block far infrared rays and molding is performed while suppressing foaming of powdered resin within the undercut. 2. A film-like film having a foamed resin layer according to claim 1, characterized in that the undercut part of the mold is kept at a lower temperature than other parts, and the amount of powdered resin adhered to the undercut part is reduced in advance. Method of manufacturing molded products. 3. According to claim 1 or 2, the far-infrared heating is performed from outside the opening of the mold,
A method for producing a film-like molded product having a foamed resin layer.