JPH0367621A - Manufacture of double layer resin molded product having foamed layer - Google Patents

Abstract

PURPOSE:To eliminate generation of flashes, waste of raw materials and deterioration of physical properties at the time of repeated molding, by a method wherein a fringe part of a mold surface of a slush mold and the fringe part of the first resin layer are sealed respectively at the times of loading of the first and second resin powder. CONSTITUTION:The first resin powder 16 is loaded within a slush mold 10 which is provided in a bucket 18 in a standing state and a fringe part of a mold surface is sealed up with a partition wall 20, to begin with. Therefore, the first resin layer 23 is stuck to and formed on only a mold surface (a) between the partition walls 20 but not stuck to an outer stretched part (b) of the mold. Then after discharge of the surplus first resin powder 16, the second resin powder 24 is loaded within the mold 10 sealed with a partition wall 28 provided into the second bucket 26 which is more to the center of the mold surface than the firs partition wall 20. Therefore, the second resin layer 32 adheres to only a space between the partition walls 28. Both the resin layers 23, 32 are melted and foamed completely with potential heat of a mold surface. Then when a molded product is taken out of the slush mold 10, a resin molded product 34 of double layer 36, 38 having a desired foamed layer is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for manufacturing a two-layer resin molded article having a foam layer used for automobile interior materials, such as console boxes and glove box lids.

(Prior Art) Conventionally, f! was disclosed in Japanese Patent Publication No. 63-27167 etc. as a method for manufacturing a two-layer resin molded product having a foam layer.
There is an A method.

The manufacturing method is to put a thermoplastic resin composition such as resin powder into a heated slush mold and
After adhering the fat layer to the mold surface and discharging the excess resin composition from the mold, a resin composition containing a foaming agent is put into the slush mold to form a foamable resin layer on the first resin layer. This is a method in which the first resin layer and the foamable resin layer are melted by the heat retained on the mold surface, and the foamable resin layer is foamed, after the excess resin composition is discharged from the mold.

Incidentally, the resin composition is usually introduced into the slush mold and adhered thereto as follows. That is, a slush mold is attached to a mold holding frame with the opening of the mold facing downward, and a bucket containing the resin composition is installed from below into the opening of the slush mold.
This is done by rotating the bucket and slush mold 180 degrees to position the bucket upward, thereby causing the resin composition in the bucket to fall into the mold.

On the other hand, the excess resin composition is discharged by rotating the bucket and slush mold, positioning the bucket again below the slush mold, and letting the excess resin composition in the mold fall into the bucket. Ru.

(Problems to be Solved by the Invention) However, the mold surface of the slush mold is continuous with the mold surface part for forming the product and the mold outer part for attaching the mold. When it is poured into the mold, the resin composition also adheres to the outer part of the mold, forming flakes around the outer periphery of the product.Therefore, not only is it necessary to remove the flakes, but there is also a large loss of raw materials. There are drawbacks.

Furthermore, from the viewpoint of energy saving, the heating of the slush mold is such that only the mold surface portion constituting the product portion is heated to a predetermined temperature, so that the temperature of the outer extension of the mold is below the predetermined temperature. Therefore, melting of the resin composition attached to the mold outer extension part,
Gelification is not performed sufficiently, and a film with insufficient physical properties is formed on the outer part of the mold.

As a result, when the molded product is taken out, the film on the outer part of the mold is not peeled off from the outer part of the mold, and often breaks from the product part and remains in the mold. Furthermore, the film with insufficient physical properties remaining on the mold surface may be mixed into the resin composition to be added during the next manufacturing process, thereby reducing the physical properties of the molded product subsequently obtained.

In particular, if the foamed resin layer protrudes from the first resin layer and is directly attached to the mold extension, the foamed resin layer attached to the mold extension will have significantly poor physical properties due to poor foaming caused by insufficient heating. Become.

Therefore, the problem arises that not only does the foamed resin layer tend to remain on the mold surface extension part when the molded product is taken out, but also that the physical properties of the molded product obtained by subsequent repeated manufacturing are significantly deteriorated.

Therefore, in view of the above points, this invention has been devised to produce a two-layer resin molded product having a foam layer, which reduces unnecessary foam and raw material loss, and does not cause deterioration of the physical properties of the molded product during repeated manufacturing. We aim to provide the following.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a first bucket containing a first resin powder in an opening of a slush mold, and a first bucket containing a first resin powder. A first resin layer is deposited on the heating mold surface by dropping it into a slush mold, and after expelling excess first resin powder from the mold, a second resin powder containing a foaming agent is stored. A second bucket is placed in the opening of the slush mold instead of the first bucket, and the second resin powder is dropped into the slush mold to form a second resin powder on the first resin layer. After the resin layer is adhered and formed and the excess second resin powder is discharged, the first resin layer and the second resin layer are melted and foamed together by the heat retained on the mold surface, and then the molded product is placed in a slush mold. In a method of manufacturing a two-layer resin molded product having a foam layer by removing the foam from the mold, the tip of the partition wall installed in the first bucket is brought into close contact with the edge of the mold surface of the slush mold to seal that part. , the first resin powder is poured into the mold between the partition walls to form a first resin layer, and after the excess first resin powder is discharged, the tip of the partition wall placed upright is placed in the second bucket. The edge surface of the first resin layer, which is closer to the center of the mold surface than the sealing position, is brought into close contact with the edge surface of the first resin layer to seal that part, and a second resin powder is poured into the mold between the partition walls, and the first resin powder is poured into the mold. The second resin layer was deposited on top of the layer.

(Function) When charging the first resin powder, the slush mold
The edges of the mold surface are sealed by the partition walls erected in the bucket, and the first resin powder is charged into the mold between the partition walls. Therefore, the first resin layer is adhered and formed only on the mold surface between the partition walls, and the first resin powder does not adhere to the mold outer extension where the mold surface temperature is below a predetermined temperature.

Furthermore, when introducing the second resin powder, the first resin powder is placed closer to the center of the mold surface than the sealing position by the partition wall of the first bucket.
The surface of the resin layer is sealed by a partition wall erected on the second bucket. Then, a second resin powder is poured into the mold between the partition walls of the second bucket. Therefore, the second resin layer adheres only to the surface of the first resin layer between the partition walls, and the second resin powder does not directly adhere to the mold extension portion outside the first resin layer.

In this way, both the first resin layer and the second resin layer are adhered and formed only on the mold surface that is heated to a predetermined temperature, so that both of the resin layers are completely melted by the heat retained by the mold surface. As the resin gels, the second resin layer is sufficiently foamed to form a two-layer molded product having a foamed layer on the mold surface. Therefore, the physical properties of the periphery of the molded product will not become insufficient, and moreover, there will be almost no formation of excess parts such as fringes.

If the molded product is then removed from the slush mold, a two-layer resin molded product having the desired foam layer is obtained. When the molded product is removed from the mold, since the molded product has sufficient physical properties up to the peripheral edge, the peripheral edge does not easily peel off from the mold surface and does not remain attached to the mold surface.

(Implementation rIA) FIGS. 1 to 7 are cross-sectional views showing manufacturing steps according to an embodiment of the present invention. The process will be explained below according to this process diagram.

The slush mold 10 to be used consists of a mold surface part a for molding a product, and a mold outer extension part for attaching the slush mold 10 to a frame 12, and the mold surface part a is attached to the outside surface of the mold. A heat medium circulation pipe 14 for heating to a predetermined temperature is provided.

As for attachment, the frame 12 holds the slush mold 10 and rotates or swings the slush mold 10 when charging or discharging the resin balater.

■ First resin layer adhesion forming process (Figs. 1 to 3) First, the slush mold 10 is mounted and fixed to the frame 12, and the opening 14 of the mold faces downward. The first resin powder 16 is housed from the bottom.
The bucket 18 is placed in the slush mold 10.

The first bucket 18 has a surrounding wall portion 19 that is fixed to the slush mold, and has an inner bottom surface with a gap C that is equal to or slightly larger than the width of the mold surface portion a of the slush mold. A partition wall 20 is erected. The bulkhead 2
A first resin powder is stored between the holes. The partition wall 20 of the bucket is for the purpose of closely contacting the edge of the mold surface of the slush mold to seal the contact area, and the partition wall tip is made of a flexible material with excellent heat resistance,
A sealing material 22 made of, for example, foamed silicone rubber is provided.

The first resin powder 16 stored in the first bucket is a thermoplastic resin powder used in normal powder slush molding. For example, it is a powder mainly composed of vinyl chloride resin. Note that the resin powder usually contains a plasticizer, a filler, a coloring agent, and the like.

Then, heated oil or the like is passed through the heat medium circulation pipe 14 of the slush mold, and the surface portion a of the slush mold 1° is heated to 140 to 200°C, and the slush mold 10 and the first bucket are heated in this heated state. 18 to 180
'' to position the first bucket above the slush mold lO. As a result, the first resin powder 16 in the first bucket is transferred to the partition wall 2 of the bucket.
The mold surface portion a of the slush mold 10 surrounded by 0
It falls and is thrown in.

The charged first resin powder adheres to the mold surface portion a due to the heat of the mold surface, and the first resin layer 23 is formed on the mold surface portion a. Furthermore, since the mold surface portion a is sealed by the partition wall 20, the first resin powder 16 is applied to the mold outer extension portion.
will not stick to the surface.

In addition, depending on the mold surface shape of the slush mold 10,
If the slush mold 10 and the bucket 18 are simply placed upside down on the floor, the first resin layer may not be formed well and uniformly, and in that case, the slush mold 1
0 and the bucket 18 are preferably rocked or rotated.

Next, the slush mold 10 and the first bucket 18
is rotated 180° and the first bucket 18 is placed below the slush mold 10 again, and the excess first resin powder 16 that did not adhere to the mold surface is discharged from the slush mold and collected into the bucket 18. do.

■ Second resin layer adhesion formation process (Figures 4 to 6) Second bucket 2 containing second resin powder 24
6 is replaced with the first bucket 18 and the slush mold 1 is used.
Attach it to the opening of 0.

A partition wall 28 is erected on the inner bottom surface of the second bucket 26 with a spacing d slightly smaller than the spacing C between the partition walls 20 of the first bucket 18, and a second resin powder is placed between the partition walls 28. 24 are stored. The partition wall 28 has a sealing material 30 at its tip, and the sealing material 30 closely contacts the edge of the first resin layer 23 to seal that portion.

The second resin powder 24 is a thermoplastic resin raw material containing a foaming agent. As the thermoplastic resin raw material, the same material as the first resin powder can be used, and as the blowing agent, an organic or inorganic pyrolyzable blowing agent that decomposes and foams during slush molding, such as azodicarbonate, can be used. Amide, 2.2°-azobisisobutyronitrile, sodium bicarbonate, ammonium carbonate, etc. can be used.

Then, the slush mold 10 and the second bucket 2
6 is rotated 1800 times to position the second bucket 26 above the slush mold 10. As a result, the second resin powder 24 is dropped and introduced into the mold between the partition walls 28. At this time, since the edge of the first resin layer 23 is sealed by the partition wall 28 of the second bucket 26, the second resin powder 24 adheres only to the surface of the first resin layer 23 and the second resin Layer 32 is formed.

At this time, as described in the formation of the first resin layer, the slush mold 10 and the second bucket 26 are oscillated and rotated as necessary.

After that, the slush mold 10 and the second bucket 2
6 is rotated 180'' to place the second bucket 26 below the slush mold 10, and the excess second resin powder 24 is discharged from the slush mold 10 and stored in the second bucket 26.

■ Melting and foaming process After forming the second resin layer 32, the mold surface temperature of the slush mold lO is heated to usually 160 to 250°C to melt and gel the first resin layer 23 and the second resin layer 32. At the same time, the second resin layer 32 is foamed. As a result, a two-layer molded product is formed on the mold surface, in which the foam layer made of the second resin layer is integrated with the film made of the first resin layer. At this time, the first resin layer 23 adheres only to the mold surface portion heated to a predetermined temperature, and the second resin layer 32 adheres only to the surface of the first resin layer 23, both of which are heated to a predetermined temperature. Since it does not adhere to the mold outer part where the temperature is low, it is heated to a predetermined temperature and completely melts, gels, and foams, forming a molded product with good physical properties.

■ Removal process of molded product (Fig. 7) The two-layer molded product is peeled off from the mold surface of the slush mold 10 and the two-layer resin molded product 34 having the desired foam layer is taken out. At this time, the first Since the film 36 made of the resin layer is completely melted and gelled and has good physical properties, it does not tear and remain in the mold adhering to the mold surface, and the foamed layer 38 made of the second resin layer is a film 3 with good physical properties.
Since it is integrated with the 6 surface and does not directly adhere to the mold surface, it is peeled off from the mold surface together with the film, and does not remain in the mold while adhering to the mold surface due to breakage or the like.

FIG. 8 is a sectional view of a two-layer resin molded product 34 having a foamed layer thus obtained. The resin molded product 34 has almost no paris, so there is no need for paris removal work.
Moreover, even if there is paris, it is extremely small and can be easily removed.

(Effects) The present invention provides a method for slush molding a two-layer resin molded product having a foam layer by sequentially introducing and discharging a first resin powder and a second resin powder into a slush mold as described above. , the edge of the mold surface of the slush mold is sealed when the first resin powder is introduced, and the edge of the first resin layer is sealed when the second resin powder is introduced.

Therefore, the resin powder can be applied only to the mold surface, which is the product forming area, and no raw materials are wasted.

Further, since the resin powder does not adhere to the mold outer extension where the mold surface temperature is below a predetermined temperature, physical property defects at the edges of the molded product due to insufficient heating will not occur. As a result, when the molded product is removed, the parts with poor physical properties do not tear and remain attached to the mold surface, and even when molding is repeated afterwards, the parts with poor physical properties are mixed into the resin powder and the resulting molded product has good properties. There is no risk of a decline.

[Brief explanation of drawings]

1 to 7 are cross-sectional views showing the manufacturing process according to an embodiment of the present invention, and FIG. 8 is a cross-sectional view of a two-layer resin molded product having a foam layer obtained by implementing the present invention. .

Claims (1)

[Claims] A first bucket containing a first resin powder is installed in the opening of a slush mold, and the first resin powder is dropped into the slush mold and applied to the surface of the heating mold. After the first resin layer is deposited and the excess first resin powder is discharged from the mold, a second bucket containing a second resin powder containing a foaming agent is substituted for the first bucket. The device is placed in the opening of the slush mold, and the second
of resin powder is dropped into a slush mold to form a second resin layer on the first resin layer, and the excess second resin layer is deposited on the first resin layer.
After discharging the resin powder of In the method for manufacturing a resin molded product, (1) the tip of the partition wall erected in the first bucket,
The slush mold is brought into close contact with the edge of the mold surface to seal this part, and a first resin powder is introduced into the mold between the partition walls to form a first resin layer, (2) excess After discharging the first resin powder, the tip of the partition wall installed in the second bucket is brought into close contact with the edge surface of the first resin layer, which is closer to the center of the mold surface than the sealing position, to seal that part. , manufacturing a two-layer resin molded product having a foam layer, characterized in that a second resin powder is put into a mold between the partition walls, and a second resin layer is adhered and formed on the first resin layer. Method.