JPH08142061A - Surface material of mold for in-mold foam molding and mold using the same - Google Patents

Abstract

PURPOSE: To obtain a molded object characterized in that the attaching mark (welding mark) of a mold surface material is not developed and hexagonal patterns of foamed particles or steam pore marks are erased by the shape of the mold surface material and having a good appearance. CONSTITUTION: A bolt 13 is welded to the rear surface of a mold surface material 1 composed of a sintered element consisting of a plurality of perforated metal plates and having pores permitting a heating medium to pass to attach the mold surface material 1 to the inner surface 11a of a mold by the bolt 13.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an in-mold foam molding die surface material and an in-mold foam molding die using the surface material.
More specifically, it is easy to attach to the mold, the attachment mark does not remain on the surface of the molded body, and the hexagonal pattern of the pre-expanded particles is erased by the transfer of the design of the surface layer of the surface material. The present invention relates to a mold surface material that provides a good molded article and a mold using the same.

[0002]

2. Description of the Related Art In-mold foam moldings of polyolefin resins such as polyethylene and polypropylene and polystyrene resins are manufactured by filling these pre-expanded particles in a mold and heating and fusing with steam or the like. . However,
Not only the hexagonal pattern of pre-expanded particles appears on the surface of the obtained molded product, but also traces of steam holes, hot air holes and extrusion pins remain, which significantly impairs the appearance of the molded product and reduces the commercial value. . Further, in order to uniformly heat the pre-expanded particles, it is necessary to provide a large number of steam holes and hot air holes, which is troublesome and increases the cost of the mold.

In order to solve such a problem, Japanese Patent Publication No. 63-63
No. 11138 discloses a method of molding using a mold in which a metal screen is mounted on the inner wall of the mold.

[0004]

DISCLOSURE OF THE INVENTION Problem to be Solved by the Invention
According to the method described in Japanese Patent Laid-Open No. 11138, although the above-mentioned problems of the prior art are solved, when a metal screen is attached with a fixture on its back surface and the fixture is attached to the inner wall of the mold, the fixture is welded. At the time of welding, the molten metal circulates to the surface layer portion of the screen, and as a result of the welding traces remaining on the surface of the screen, the welding traces appear on the surface of the molded body and pose a new problem. Further, when the metal screen is fixed with screws or bolts from the surface, the heads of the screws or bolts are transferred to the surface of the molded body, and the appearance of the molded body is likewise impaired. Therefore, the above method has not been put to practical use until now.

The present invention solves the problem that a mark for attaching a metal screen to a mold remains, and provides a mold surface material and a mold using the same for providing a molded product having a good appearance. It is a thing.

[0006]

Means for Solving the Problems As a result of intensive research aimed at solving the above-mentioned problems, the present inventors have found that a plurality of porous metal plates are sintered and integrated, and the back surface of the metal plates is attached to the inner surface of the mold. The present inventors have completed the present invention by finding that the attachment mark does not appear on the surface of the die surface material, and therefore the attachment mark does not appear on the surface of the molded article, and that a molded article having a good appearance can be manufactured. That is, the first aspect of the present invention is a mold surface material for in-mold foam molding, which comprises a plurality of porous metal plates and is made of a sintered body having pores through which a heating medium passes. The contents are the in-mold foam molding dies in which the back surface of the die surface material is attached to all or part of the inner surface of the die.

[0007]

The mold surface material of the present invention is composed of a plurality of porous metal plates, and is composed of a sintered body having pores through which the heating container medium passes, and is attached to the inner surface of the mold by the back surface of the surface material. ,
That is, since it is made by the porous metal plate that constitutes the lower layer portion, for example, when the fixture is attached to the back surface of the die surface material by welding, the molten metal can be attached without turning to the surface layer portion of the surface material. Therefore, a molded product having a good appearance without the appearance of mounting marks can be obtained. Further, the pores on the back surface of the surface material of the portion where the fixture is attached are closed, but the pores from the upper layer portion to the surface are not closed, so that passage of the heating medium such as steam or hot air is hardly obstructed.
Therefore, a molded product having a good fusion property can be obtained. Furthermore, since it is not necessary to pay attention to the traces of welding on the surface layer of the die surface material, the work of attaching the fixture to the die surface material becomes easy, and in the end, the work of attaching the surface material to the die Efficiency is greatly increased. Further, by attaching the die surface material such that the end portion is laid under the die inner surface member or bited into the die inner surface member, the edge portion can be clearly exposed.

Furthermore, since steam and hot air are uniformly introduced into the mold through the pores of the surface material of the mold to heat the pre-expanded particles, it is possible to obtain a molded product having good fusion property without uneven heating. Further, since it is possible to perform uniform heating without providing a large number of steam holes and hot air holes in the mold unlike the conventional case, it is possible to reduce the mold cost.

[0009]

EXAMPLES The porous metal plate used in the present invention has a large number of pores through which a heating medium such as steam or hot air can pass. For example, a wire mesh or a metal plate is provided with a large number of pores. Punching metal etc. are mentioned.

The pores of the wire mesh and punching metal depend on the number of sintered and integrated pieces, but usually about 4 to 100 mesh, preferably about 10 to 30 mesh wire mesh, 1 cm ²
About 10 to 2000 pieces, preferably 15 to 250 pieces
It is desirable that the holes be provided with about several pores. If the pores are too large, traces of pores will appear in the molded product, and if the pores are too small, the pores will be easily clogged, and the hexagonal pattern will be hard to disappear.

The thickness of the wire netting and punching metal is not particularly limited, and in consideration of the strength of the die surface material, the ease of mounting, etc., an appropriate number of sheets can be sintered and integrated to obtain a desired thickness. Good. The surface layer portion in contact with the molded body of the die surface material may be a wire net or a punching metal, but the wire net is preferred because the irregularities of the wire net can effectively eliminate the hexagonal pattern of the particles. The lower layer is made of wire mesh, punching metal, or a combination of both. The wire mesh and punching metal forming the surface layer portion and the lower layer portion may have the same mesh or different meshes, and may have the same degree of perforation or different degree of perforation.

As described above, the number of wire nets and / or punching metals to be sintered and integrated may be appropriately selected so as to have a desired thickness in view of strength as a die surface material, ease of attachment, and the like. In the case of a united body, it is necessary to have at least pores through which a heating medium such as steam or hot air can pass. If the number of sheets is too large, the manufacturing efficiency becomes poor and the cost becomes high. Therefore, it is desirable to select from about 2 to 6 sheets.

The die surface material as described above is attached to the inner surface of the die by attaching means such as welding. In this case, it is preferable to attach a mounting tool such as a bolt to the back surface of the die surface material by welding or the like, and attach it to the inner surface of the die with a nut or the like.

An embodiment of the present invention will be described below with reference to the drawings. In the die surface material 1 of FIG. 1, a surface layer portion made of a wire mesh 2 and a lower layer portion made of a punching metal 3 are sintered and integrated. The mold surface material 1 of FIG. 2 includes a surface layer portion composed of a metal mesh 2a, a metal mesh 2b having the same mesh as the metal mesh 2a,
The lower layer portion composed of 2b is sintered and integrated. The mold surface material 1 of FIG. 3 includes a surface layer portion composed of a wire mesh 2a and a wire mesh 2a.
The metal meshes 2b, 2b and 2b having different meshes are sintered and integrated.

The surface material of the die is preferably coated with a fluorine resin on the surface layer of the surface material in order to improve the releasability of the molded product. Examples of such a fluorine resin include tetrafluoroethylene / hexafluoropropylene copolymer resin, tetrafluoroethylene resin and the like.

The mold surface material as described above is attached to all or a part of the inner surface of the mold with which the molded body is in contact. As a mounting method, a method of welding a bolt to the back surface of the die surface material, inserting the bolt into a bolt hole provided on the inner surface of the die, and tightening it with a nut is preferable. If necessary, screws can be used together. Since the die surface material of the present invention is made of a sintered body, it can be attached without causing the welding trace to remain in the lower layer portion of the surface material and appear on the surface of the surface layer portion as described above. Also, a method of attaching bolts to the lower part or the back part that constitutes the surface material of the mold by welding in advance and then sintering and integrating this with the surface part or the upper part also ensures that welding traces appear on the surface part of the surface part. It is a preferable method for preventing the above. When it is attached to a part of the inner surface of the mold, it is preferably attached to the horizontal portion of the inner surface of the die and an inclined portion close to the horizontal portion. This is because this portion forms a horizontal portion of the molded body or an inclined portion close to the horizontal portion, which greatly affects the appearance of the molded body.

When the die surface material is attached to the inner surface of the die, if the end portion of the die surface material is attached so as to contact the inner surface member of the die to be attached, the edge portion formed by both is clearly exposed. If it is not, it will be in a partially collapsed state, and a molded product with a deteriorated appearance tends to be formed. In order to avoid this, it is desirable that at least the end portion of the die surface material is laid under the die inner surface member or attached so as to bite into the die inner surface member.

4 to 6 are schematic sectional views showing an example in which the mold surface material of the present invention is partially attached to the mold. In these figures, 11 is a core mold, 12 is a cavity mold, and the mold surface material 1 is attached to the horizontal portion 11a of the inner surface of the core mold 11 with bolts, nuts 13 and screws 14. There is. Reference numeral 15 is a steam hole, and 16 is a molding space.

Incidentally, for example, in the edge portion E shown by the arrow in FIG. 4, the mold surface material is not laid on the mold surface member, but since these parts are not so conspicuous parts of the molded body, there is usually a problem. Does not mean Of course, when it is desired to form a clean edge also in these edge portions, it may be mounted so that a part of the die surface material is laid on or dig into the die inner surface member.

Further, for example, in FIGS. 5 and 6, the portion of the die surface material 1a slightly reduces the passage of steam and hot air in the portion of the die surface material 1b, and the supply of the cooling water becomes poor. In some cases, the molded product in the portion may be insufficiently cooled or may be poorly cooled, which may cause sink marks, defective dimensions, or poor appearance of the molded product. Therefore, in the case of a resin or a molded body in which such a problem is feared, it is preferable to use a mold that does not have such a problem as shown in FIG.

The present invention will be described in more detail based on the following examples, but they are not intended to limit the present invention.

Example 1 A sintered body composed of five 16-mesh wire nets (thickness: 2.5 m
The surface layer of m) is coated with a tetrafluoroethylene / hexafluoropropylene copolymer resin, and the mold surface material is partially attached to the inner surface of the core mold with bolts, nuts and screws, and the structure shown in FIG. Got the mold. Next, pre-expanded polyolefin resin particles "Eperan PP (Kanebuchi Chemical Industry Co., Ltd., foaming ratio: 30 times)" were placed in a pressure vessel in advance and an internal pressure of 2 kg / cm ² was given by vapor pressure. After the crack was filled in the molding space with the gap between the core mold and the cavity mold of the mold being 7 mm, both the core mold and the cavity mold were clamped and molded under the following conditions.

One-side heating 1.0 kg / cm ² Reverse one-side heating 1.2 〃 Double-sided heating 3.4 〃 Heat retention 5 seconds Pre-cooling 3 〃 Water cooling 110 〃 Cooling 10 〃 The obtained molded body is a 16 mesh wire mesh The mesh was transferred to the surface of the molded product, and the hexagonal pattern of the foamed particles and traces of steam holes were hardly noticeable, and the bolt had a beautiful appearance with no trace of welding.

Example 2 Two 16-mesh wire nets (thickness: 0.55 mm) and punching metal (hole diameter: 10 mm, pitch: 13, thickness 2)
mm), the surface layer (metal mesh) of a sintered body is coated with a tetrafluoroethylene / hexafluoropropylene copolymer resin, and is used as a pre-expanded polyolefin resin particle "Eperan XL (Kanebuchi)". Made by Chemical Industry Co., Ltd.
Foaming ratio: 38 times) "was used and the molding was carried out in the same manner as in Example 1 except that the molding conditions were as follows.

One-side heating 0.4 kg / cm ² Reverse one-side heating 0.6 〃 Double-sided heating 1.2 〃 Heat retention 5 seconds Pre-cooling 3 〃 Water cooling 70 〃 Cooling 5 〃 Similarly, it had a beautiful appearance.

Example 3 Punching metal (hole diameter: 0.5 mm, pitch: 1.1)
mm, thickness 0.4 mm) 1 layer, 2 pieces of 32 mesh wire mesh and 2 pieces of 16 mesh wire mesh The surface layer part (punching metal) of a sintered body is made of tetrafluoroethylene / hexafluoropropylene copolymer resin. Molding was performed in the same manner as in Example 1 except that the coated die surface material was used. In the obtained molded body, the pores of punching metal are transferred to the surface of the molded body,
Similar to Example 1, it had a beautiful appearance.

Comparative Example 1 Molding was carried out in the same manner as in Example 1 except that a mold in which a 16-mesh wire net (thickness: 0.55 mm) was attached in the same manner as in Example 1 was used. The obtained molded body had a 16 mesh wire mesh transferred to the surface of the molded body, and the hexagonal pattern of the foamed particles and traces of steam holes were hardly noticeable, but welding traces of bolts appeared and the appearance was poor. It was

Comparative Example 2 In Example 2, the two wire nets and the one punching metal were not used as the sintered body, but the two wire nets and the one punching metal were integrated in a state of being simply superposed. It was attached to a mold and molded in the same manner as in 2. In this case,
Since it is necessary to weld and integrate the surface layer portion, the molten metal circulates to the surface layer portion, and the obtained molded body has the weld trace of the bolt as in the case of Comparative Example 1 and has an inferior appearance. It was

[0029]

As described above, according to the present invention, molding with a beautiful appearance and high commercial value, in which not only the hexagonal pattern of the expanded particles but also the traces of welding (welding traces) of the die surface material, do not appear. The body can be provided.

[Brief description of drawings]

FIG. 1 is a schematic view showing an example of a die surface material of the present invention.

FIG. 2 is a schematic view showing another embodiment of the die surface material of the present invention.

FIG. 3 is a schematic view showing still another embodiment of the die surface material of the present invention.

FIG. 4 is a schematic view showing an embodiment of a mold of the present invention.

FIG. 5 is a schematic view showing an embodiment of a mold of the present invention.

FIG. 6 is a schematic view showing an embodiment of the mold of the present invention.

[Explanation of symbols]

 1, 1a, 1b Mold surface material 2, 2a, 2b Wire mesh 3 Punching metal 11 Core mold 12 Cavity mold 13 Bolts and nuts 14 Screws 15 Steam holes 16 Molding space

Claims (7)

[Claims] 1. An in-mold foam molding die surface material comprising a sintered body comprising a plurality of porous metal plates and having pores through which a heating medium passes. 2. The mold surface material according to claim 1, wherein the porous metal plate is a wire mesh or a punching metal. 3. The mold surface material according to claim 1, wherein the surface layer portion is a wire mesh. 4. The mold surface material according to claim 1, wherein the surface layer portion is coated with a fluorine-based resin. 5. A mold for in-mold foam molding, wherein the back surface of the mold surface material according to claim 1 is attached to all or part of the inner surface of the mold. 6. The in-mold foam molding die according to claim 5, wherein the die surface material is attached so that an end portion of the die surface material is laid under the die inner surface member or bited into the die inner surface member. Type. 7. The in-mold foam molding die according to claim 5, wherein a fixture is welded to the back surface of the die surface material and attached to the inner surface of the die.