JPH0558370B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for manufacturing 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 powder resins 14 are welded together and attached to the mold surface to a predetermined thickness, and then the slush mold 12 is turned over. Excess powdered 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.

On the other hand, in order to manufacture a film-like molded product formed by laminating a non-foamed resin layer and a foamed resin layer,
As described in Japanese Patent No. 101014, first, powdered resin that does not contain a 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.

Incidentally, the film-like molded product having the foamed resin layer obtained as described above was originally formed using the slush mold 1.
The part below the A-A section in No. 2 is the product part. However, in order to obtain a homogeneous film-like molded product, the slush mold 12 is provided with an extended surface 13a that expands following the opening edge of the slush mold 12, and powdered resin is adhered to the mold surface and the extended surface 13a, and then heated in a series. It is melted and molded into a large film-like molded article.

The film-like molded product having the foamed resin layer produced in this way is then placed in a foam mold, and a liquid foam raw material such as a polyurethane foam raw material is injected into the inner surface of the film-like molded product, and integral foam molding is performed. served. At this time, the film-like molded product is held in the foaming mold by sandwiching the film extension formed by the mold surface extension surface 13a between the lower mold and the upper mold. After the foam molding, the extension part of the film-like molded product is cut off from A-A along with the protrusion (burr) of the foam, and the mold surface 1 of the slush mold
The film-like molded product formed in step 3 becomes the epidermis.

(Problems to be Solved by the Invention) Depending on the shape of the film-like molded product having a foamed resin layer, during the production of the film-like molded product,
There are cases where it is desired to partially suppress foaming of a powder resin layer containing a foaming agent.

For example, this is the case when manufacturing a film-like molded product having a foamed resin layer with a portion bent outward to have a substantially U-shaped cross section. In this case, a film-like molded product is manufactured in the same manner as described above using a slush mold 12 having a recess 15 on the mold surface that matches the bent shape. However, in the recess 15 of the slush mold, the powder resin foams and the foamed resin layer 17 approaches each other as shown in broken lines as shown in FIG. The surfaces of the foamed resin layer 17 may be welded to each other by drawing air 19 inside, forming a bridge 16. Even if the foamed resin layer in which the bridges 16 are formed shrinks due to subsequent cooling, the bridges 16 will not separate and will remain blocking the inside of the recess (inside the bent part of the film-like molded product). . As a result, even if an attempt is made to integrally foam the film-like molded product as a skin, the liquid foam raw material such as polyurethane foam raw material injected into the inner surface of the film-like molded product is blocked by the bridges 16 and It is not possible to enter the bent part of the film-like molded product, and only a defective skin-integrated foamed molded product is obtained that has no stiffness at the bent part or has a different feel (softness) between the bent part and other parts.

Therefore, an attempt is made to suppress the foaming of the powder resin layer in the recess 15 of the slush mold to prevent the formation of bridges 16 due to welding on the surface of the foamed resin layer.

However, in order to partially suppress the foaming of the powder resin layer, the heating temperature in a predetermined part of the slush mold is set lower than in other parts to suppress the thermal decomposition of the blowing agent contained in the powder resin adhered to that part. However, since the slush mold is made of metal or the like with excellent heat conductivity, it is not easy to partially lower the temperature of the slush mold.

Therefore, in the past, instead of partially lowering the temperature of the slush mold, the mold surface recess 1
By making the wall spacing d of 5 sufficiently large, the surface of the foamed resin layer is prevented from welding in the recess 15 and blocking the inside of the bend.

Therefore, the shape of the mold surface recess 15, ie, the shape of the film-like molded product having the foamed resin layer, is restricted, and the design of the entire molded product has low flexibility.

In addition to the above, depending on the use of a film-like molded product having a foamed resin layer, there are cases where it is desired to partially suppress the foaming of the powdered resin to partially reduce the thickness of the foamed resin layer. Even in that case, it was difficult to partially lower the mold surface temperature of the slush mold as described above, and therefore a molded product having the desired thickness change could not be obtained.

The present invention has been made in view of the above points, and is a film having a foamed resin layer that can be molded while suppressing foaming of the powdered resin layer attached to a predetermined portion in a slush mold compared to other portions. The present invention aims to provide a method for manufacturing shaped molded articles.

(Means for Solving the Problems) In order to achieve the above object, in the present invention, powdered resin containing a foaming agent is charged into a slush mold, and the powdered resin layer is heated. In a method of manufacturing a film-like molded product having a foamed resin layer by melting the powder and decomposing the foaming agent, air is blown onto the surface of a predetermined part of the powder resin layer when heating the powder resin layer to lower the temperature of the part. This allows molding to be carried out while suppressing foaming.

Furthermore, if there is a narrow recess on the mold surface of the slush mold, air is blown onto the surface of the powder resin layer adhering to the recess to lower the temperature of the surface of the powder resin layer in that area.

(Function) The powder resin layer containing the foaming agent that is put into the slush mold and adhered inside the slush mold is heated and melted, and the foaming agent is thermally decomposed and foamed, forming a film having a foamed resin layer. It becomes a shaped molded product. At this time, air is blown onto the surface of a predetermined portion of the powder resin layer so that the temperature thereof is lower than that of the surface of other portions, so that decomposition of the foaming agent is suppressed more than in other portions, and foaming is suppressed. As a result, the foamed resin layer formed by foaming the powdered resin layer has a thickness that is thinner in the portion where air is blown than in other portions.

In addition, when the part to which air is blown is the surface of the powder resin layer attached to the narrow recess on the mold surface of the slush mold, and the temperature of the powder resin in this part is lowered to suppress foaming of the powder resin layer, Since the swelling of the foamed resin layer formed by the foaming can be reduced, the surface of the foamed resin layer does not come into close contact with the concave portions,
The recess is never blocked.

(Example) Hereinafter, a case will be described in which a film-like molded product formed by laminating a non-foamed resin layer and a foamed resin layer is manufactured using a slush mold having a narrow recess on the mold surface.

First, the powdered resin forming the non-foamed resin layer and the foamed resin layer will be explained. The powdered resin (hereinafter referred to as the first powdered resin) forming the non-foamed resin layer is:
Usually, a powdered thermoplastic resin such as vinyl chloride resin is used, with auxiliary agents such as stabilizers, plasticizers, and flame retardants added. 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 forming side 20 used in one embodiment of the present invention.

This slush mold 20 has a narrow recess 22 formed at a predetermined portion of the mold surface, and has a pipe 24 for circulating a heat medium on the outer surface of the mold for heating the mold surface.

First, the opening of the slush mold 20 is inserted into the bucket 28 housed in the first powdered resin 26.
The slush mold 20 and bucket 28 are rotated while the mold surface is preheated to 140 to 250°C by heated oil passing through the circulation pipe 24 on the outside of the mold, and the first powder resin 26 in the bucket is It 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 26 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 of the slush mold 20 is closed with a bucket (not shown) containing a second powdered resin containing a foaming agent. 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.

Then, as shown in FIG. 2, a far-infrared heater 30 is placed above 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 from the surface. do. 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. Heating temperature is usually 160-250℃
That's about it. Also, when heating from both sides, the second powder resin layer 32a adheres to the narrow recess 22 of the mold surface.
Air 35 is blown onto the surface to lower the temperature of the area. Note that the heating means is not limited to heating oil or far infrared rays, but may be other known means.

By the heating, the second powder resin is melted and the foaming agent is thermally decomposed and foamed, thereby forming a foamed resin layer on the non-foamed resin layer. At this time, the surface of the foamed resin layer approaches the mold surface recess 22 in a direction that closes the recess. However, in the recess, the temperature of the second powdered resin layer is lowered by the air blowing, so thermal decomposition of the foaming agent is suppressed and foaming is suppressed, so that the surface of the foamed resin layer is in close contact with each other. It doesn't reach that point. As a result, the obtained film-like molded product having the foamed resin layer has the shape of the recess 22.
The bent portion formed by the foamed resin layer is not covered by the foamed resin layer.

The film-like molded product having the foamed resin layer formed in this manner is removed from the slush mold after being cooled.

FIG. 3 is a sectional view of a film-like molded product 36 obtained in the above example. The molded product 36 is formed by laminating a foamed resin layer 38 on the back side of a non-foamed resin layer 33, and the surface of the foamed resin layer 38a is It is not welded and is not closed within the bent portion 40.

On the other hand, when molding is carried out by blowing air onto the surface of the powder resin resin layer containing a foaming agent adhering to a predetermined part of the mold surface other than the narrow concave part and lowering the heating temperature of the part, foaming of the part The resin layer is thinner than other parts. Note that the details can be easily understood from the above explanation, and will be omitted to avoid redundant explanation.

(Effects) The present invention has the above-described configuration, and is capable of suppressing foaming of the powder resin layer containing a foaming agent adhering to the inside of the slush mold in a desired portion. Therefore, restrictions on the mold surface shape of the slush mold, that is, restrictions on the shape of the molded product, are reduced, and there is an effect that the degree of freedom in design of the molded product can be increased. Further, there is also the effect that the thickness of the foamed resin layer can be set to the optimum thickness at a desired portion depending on the purpose and the like.

[Brief explanation of the drawing]

Figures 1 and 2 are cross-sectional views explaining one embodiment of the present invention, Figure 3 is a cross-sectional view of a film-like molded product having a foamed resin layer obtained by implementing the present invention, and Figure 4 is a powder A cross-sectional view explaining the slush molding method, and FIGS. 5 and 6 are partial cross-sectional views showing conventional manufacturing. 20... Slush mold, 22... Mold surface recess, 38... Foamed resin layer.

Claims (1)

[Claims] 1. Powdered resin containing a foaming agent is put into a slush mold, and the powdered resin layer adhering to the mold is heated to melt the powdered resin and decompose the foaming agent. In the method for manufacturing a film-like molded product having a foamed resin layer, air is blown onto the surface of a predetermined part of the powdered resin layer when the powdered resin layer is heated, thereby reducing the temperature of the part and suppressing foaming. A method for producing a film-like molded product having a foamed resin layer, the method comprising molding. 2 In claim 1, the part that blows air is
A method for manufacturing a film-like molded product having a foamed resin layer, characterized in that the powder resin layer is attached to the surface of a narrow concave portion of a slush mold.