JP2764184B2 - Method for producing two-layer resin molded article having foam layer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a two-layer resin molded article having a foamed layer used for an interior material for an automobile, for example, a console box, a glove box lid, and the like.

(Prior Art) Conventionally, as a method for producing a two-layer resin molded product having a foamed layer, there is a production method disclosed in Japanese Patent Publication No. 63-27167.

The manufacturing method is such that a thermoplastic resin composition such as a resin powder is put into a heated slush molding die, a first resin layer is adhered to a mold surface, and an excess resin composition is discharged from the die, and then foamed. The resin composition containing the agent is charged into a slash molding die to form a foamable resin layer on the first resin layer, and the excess resin composition is discharged from the die. Is a method of melting the first resin layer and the foamable resin layer and foaming the foamable resin layer.

By the way, the introduction and attachment of the resin composition into the slush mold are usually performed as follows. That is, the slash mold is attached to the mold holding frame, the opening of the mold is directed downward, a bucket containing the resin composition is installed from the bottom into the opening of the slush mold, and the bucket and the slush mold are attached. This is performed by rotating the bucket 180 degrees to position the bucket upward, thereby dropping the resin composition in the bucket into the mold.

On the other hand, the surplus resin composition is discharged by rotating the bucket and the slush mold so that the bucket is positioned below the slush mold again, and the surplus resin composition in the mold is dropped into the bucket.

(Problems to be Solved by the Invention) However, since the mold surface of the slush molding mold has a mold surface portion for forming a product and a mold extension portion for attaching the mold, the resin composition is molded. When the resin composition is charged into the mold, the resin composition also adheres to the extension of the mold, and burrs are formed on the outer periphery of the product. Therefore, there is a disadvantage that not only the operation of removing the burrs is required but also the raw material loss is large. In addition, the heating of the slush mold has a structure in which only the mold surface portion constituting the product portion is heated to a predetermined temperature from the viewpoint of energy saving, and thus the temperature of the mold extension becomes lower than the predetermined temperature. Therefore, the resin composition adhered to the mold extension is not sufficiently melted and gelled, and a film having insufficient physical properties is formed on the mold extension. As a result, when the molded product is taken out, the film on the extension of the mold is often not peeled off from the extension of the mold, but is often broken from the product part and remains in the mold. Moreover,
The film having insufficient physical properties remaining on the mold surface may be mixed into the resin composition charged at the time of the next production, and the physical properties of the molded article obtained next may be reduced.

In particular, when the foamed resin layer protrudes from the first resin layer and is directly adhered to the mold extension, the foamed resin layer adhered to the mold extension becomes extremely poor in physical properties due to poor foaming caused by insufficient heating. Become. Therefore, not only does the foamed resin layer easily remain on the mold surface extension when the molded article is taken out, but also there is a problem in that the physical properties of the molded article obtained by repeated manufacturing thereafter are significantly reduced.

In view of the above, the present invention provides a method for producing a two-layer resin molded article having a foamed layer, which reduces unnecessary burrs and loss of raw materials and does not cause deterioration in physical properties of the molded article during repeated production. Is to be provided.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a first bucket in which a first resin powder is stored in an opening of a slash molding die, and the first resin powder is provided with the first bucket. The first resin layer is adhered to the surface of the heating mold by being dropped and poured into a slush molding mold, and after the excess first resin powder is discharged from the mold, the second resin powder containing a foaming agent is stored. The second bucket is placed in the opening of the slash molding die instead of the first bucket, and the second resin powder is dropped into the slush molding die and the second resin powder is dropped on the first resin layer. After forming a resin layer and discharging excess second resin powder, the first resin layer and the second resin layer are integrally melted and foamed by the heat held by the mold surface, and then the molded product is subjected to a slush molding die. By taking out from In a method for manufacturing a two-layer resin molded product having a foamed layer, a tip of a partition wall erected on a first bucket is brought into close contact with a die surface edge of a slash molding die to seal the portion, and a mold between the partition walls is formed. After the first resin powder is put into the inside, the first resin layer is attached and formed, and after the surplus first resin powder is discharged, the tip of the partition wall erected on the second bucket is closer to the mold than the sealing position. The first resin layer is brought into close contact with the edge surface of the first resin layer to seal the portion, and the second resin powder is poured into the mold between the partition walls, and the second resin is placed on the first resin layer. It was decided to deposit a layer.

(Operation) When the first resin powder is charged, the slash molding die is sealed at the edge of the mold surface by the partition wall erected on the first bucket, and the first resin powder is charged into the die between the partition walls. Is done. Therefore, the first resin layer is adhered only to the mold surface between the partition walls, and the first resin powder does not adhere to the mold extension where the mold surface temperature is equal to or lower than the predetermined temperature.

In addition, when the second resin powder is charged, the surface of the first resin layer closer to the center of the mold surface than the sealing position of the partition of the first bucket is sealed by the partition erected on the second bucket. Then, the second resin powder is put into a mold located 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 outside the first resin layer.

As described above, since both the first resin layer and the second resin layer are adhered only to the mold surface portion heated to the predetermined temperature, both resin layers are completely melted by the mold surface holding heat. As the gel is formed, the second resin layer further foams sufficiently to form a two-layer molded article having a foam layer on the mold surface. Therefore, the physical properties of the periphery of the molded product do not become insufficient, and an extra portion such as a burr is hardly formed.

Thereafter, if the molded product is taken out of the slush mold, a two-layer resin molded product having a desired foamed layer is obtained. At the time of the mold release, the molded product has sufficient physical properties up to the peripheral portion, so that the peripheral portion does not easily peel off from the mold surface and does not remain attached to the mold surface.

(Embodiment) FIGS. 1 to 7 are cross-sectional views showing manufacturing steps according to an embodiment of the present invention. Hereinafter, description will be made in accordance with this process chart.

The slash mold 10 to be used has a mold surface portion a for molding a product, and a frame on which the slash mold 10 is mounted.
The mold has an extension part b for attachment to the mold 12, and a heat medium circulation pipe 14 for heating the mold surface part a to a predetermined temperature is provided on the outer surface of the mold.

The mounting frame 12 holds the slush molding die 10 and rotates or swings the slush molding die 10 when the resin powder is charged or discharged.

First resin layer adhesion forming step (FIGS. 1 to 3)
First, the slash mold 10 is fixed to the mounting frame 12, the opening 14 of the mold is turned downward, and the first bucket 18 containing the first resin powder 16 is slashed from below the opening 14. It is set in the molding die 10.

The first bucket 18 has a peripheral wall portion 19 serving as a fixing portion to the slush mold, and an inner bottom surface having an interval c which is equal to or slightly larger than the width of the mold surface portion a of the slash mold. A partition wall 20 is provided upright. The first resin powder is stored between the partition walls 20. The partition wall 20 of the bucket has a tip portion that is in close contact with the edge of the mold surface of the slush molding die and is used for sealing the contact portion. A sealing material 22 made of foamed silicone rubber is provided.

First resin powder 16 stored in first bucket
The thermoplastic resin powder used for ordinary powder slush molding is used. For example, a powder mainly composed of a vinyl chloride resin is used. In addition, a plasticizer, a filler, a coloring agent, and the like are usually mixed in the resin powder.

Then, heating oil or the like is passed through the heat medium circulating pipe 14 of the slash molding die, and the mold surface portion a
Is heated to 140 to 200 ° C., and the slash mold 10 and the first bucket 18 are rotated by 180 ° in the heated state, and the first bucket is positioned above the slush mold 10. As a result, the first resin powder 16 in the first bucket falls into the mold surface portion a of the slash molding die 10 surrounded by the partition wall 20 of the bucket and is injected.
The supplied first resin powder adheres to the mold surface portion a by heat on the mold surface, and the first resin layer 23 is formed on the mold surface portion a. In addition, since the mold surface portion a is sealed by the partition wall 20, the first resin powder 16 does not adhere to the mold extension portion b.

In addition, depending on the mold surface shape of the slash molding die 10, etc.
Simply inverting the slash mold 10 and the bucket 18 may not be able to perform the adhesion formation of the first resin layer satisfactorily and uniformly. In this case, the slash mold 10 and the bucket 18 are swung or rotated. Is preferred.

Next, the slash mold 10 and the first bucket 18
Is rotated 180 ° so that the first bucket 18 is again below the slush molding die 10, and the excess first resin powder 16 that has not adhered to the mold surface is discharged from the slash molding die and collected in the bucket 18. I do.

Steps for forming the second resin layer (see FIGS. 4 to 6)
Figure) Second bucket 26 containing second resin powder 24
Is mounted on the opening of the slash mold 10 in place of the first bucket 18.

The first bucket is provided on the inner bottom surface of the second bucket 26.
Partition walls 28 are erected at a distance d slightly smaller than the distance c between the partition walls 20 of 18 and a second resin powder is interposed between the partition walls 28.
24 are stored. The partition wall 28 has a sealing material 30 at the tip, and the sealing material 30 is in close contact with the edge of the first resin layer 23 to seal the portion.

As the second resin powder 24, a thermoplastic resin material containing a foaming agent is used. As the thermoplastic resin raw material, the same as the first resin powder can be used, and as the foaming agent, an organic or inorganic thermal decomposition type foaming agent which decomposes and foams at the time of slush molding, for example, azodicarbonate Amides, 2,2'-azobisisobutyronitrile, sodium bicarbonate, ammonium carbonate and the like can be used.

Then, the slash mold 10 and the second bucket 26
Is rotated 180 ° to position the second bucket 26 above the slush mold 10. As a result, the second resin powder 24 is dropped and put 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 Layer 32 is formed.

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

Thereafter, the slash mold 10 and the second bucket 26
Is rotated 180 ° so that the second bucket 26 is positioned below the slush molding die 10, and the surplus second resin powder 24 is discharged from the slash molding die 10 and stored in the second bucket 26.

Melting and Foaming Step After forming the second resin layer 32, the mold surface temperature of the slush molding die 10 is usually heated to 160 to 250 ° C. to melt and gel the first resin layer 23 and the second resin layer 32. Is performed, and the second resin layer 32 is foamed. As a result, a two-layer molded product in which the film made of the first resin layer and the foamed layer made of the second resin layer are integrated, is formed on the mold surface. At this time, the first resin layer 23 adheres only to the mold surface portion heated to a predetermined temperature,
Further, since the second resin layer 32 adheres only to the surface of the first resin layer 23 and does not adhere to the mold extension portion having a low temperature, the second resin layer 32 is heated to a predetermined temperature and completely melted.
It gels and foams to form a molded article having good physical properties.

Step of Removing Molded Product (FIG. 7) The two-layer molded product is peeled off from the surface of the slush molding die 10, and a two-layer resin molded product 34 having a desired foamed layer is removed. At this time, since the film 36 composed of the first resin layer is completely melted and gelled and has good physical properties, it does not break and remain in the mold while adhering to the mold surface. Since the foamed layer 38 composed of a layer is integrated with the surface of the film 36 having good physical properties and is not directly adhered to the mold surface, the foam layer 38 is peeled off from the mold surface together with the film, and adheres to the mold surface due to breakage or the like. Will not remain in.

FIG. 8 is a sectional view of a two-layer resin molded product 34 having a foam layer obtained in this manner. The resin molded product 34
Since there are almost no burrs, no burrs are required, and even if there are very few burrs, the burrs can be easily removed.

(Effect) The present invention provides the first resin powder and the second resin powder as described above.
The resin powder of the present invention is sequentially charged and discharged into a slush molding die to form a two-layer resin molded product having a foamed layer, and the slush molding die is sealed at the time of charging the first resin powder. In addition, when the second resin powder is charged, the edge of the first resin layer is sealed.

Therefore, the resin powder can be adhered only to the mold surface as a product forming portion, and no waste of raw materials occurs.

In addition, since the resin powder does not adhere to the outer peripheral portion of the mold where the mold surface temperature is equal to or lower than the predetermined temperature, there is no occurrence of poor physical properties of the edge of the molded product due to insufficient heating. As a result, when the molded article is taken out, the defective property part is not broken and remains on the mold surface, and even when the molding is repeated thereafter, the physical property of the molded article obtained by mixing the defective property part into the resin powder is obtained. There is no danger of lowering.

[Brief description of the drawings]

1 to 7 are cross-sectional views showing a 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 foamed layer obtained by carrying out the present invention. . 10: slush mold, a: mold surface portion, b: mold extension, 16: first resin powder, 18: first bucket, 20, 28: partition, 22,30: sealing material, 24: second Resin powder, 26: second bucket, 32: second resin layer, 34: two-layer resin molded product having foam layer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI B29L 31:58

Claims (1)

(57) [Claims] 1. A first bucket containing a first resin powder is installed in an opening of a slush molding die, and the first resin powder is dropped into the slush molding die to form a first bucket on a heating die surface. The first resin layer is adhered and formed.
After discharging the resin powder from the mold, the second bucket containing the second resin powder containing the foaming agent is installed in the opening of the slash molding die in place of the first bucket, and the second bucket is provided. After dropping the resin powder into the slush molding die to form a second resin layer on the first resin layer and discharging the surplus second resin powder, the first resin is heated by the heat held by the mold surface. A method of manufacturing a two-layer resin molded product having a foamed layer by melting and foaming the layer and the second resin layer integrally, and then removing the molded product from the slash molding die, The tip of the partition wall, which has been brought into close contact with the edge of the mold surface of the slush molding die, is sealed, and the first resin powder is poured into the mold between the partition walls to adhere and form the first resin layer, After discharging excess first resin powder The tip of the partition wall erected on the second bucket is brought into close contact with the edge surface of the first resin layer closer to the center of the mold surface than the sealing position to seal the portion, and the mold is placed between the partition walls. A method for producing a two-layer resin molded article having a foamed layer, comprising charging a second resin powder and forming a second resin layer on the first resin layer.