JPH10305440A - Mold surface material for in-mold foam molding and mold using the material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a mold surface material for the in-mold foam molding for forming a foam molded body of good appearance and also provide a mold using the material. SOLUTION: A reinforcing metal plate 3 is fixed on the back of a porous metal plate of a wire mesh, a punching metal or the like constituting a surface layer 2 of a mold surface material 1 by sintering to reduce remarkably a clearance between the porous metal plate and the reinforcing metal plate 3, and the strength and durability of the surface material 1 are improved by the reinforcing metal plate 3, and the installation of the surface material 1 on a mold is carried out easily. Although it is preferable to provide a vapor passing opening 3a on a position corresponding to a vapor opening of the mold on the reinforcing metal plate 3, it is not necessarily provided. The surface material 1 is installed on the hole or a part of the in-mold surface for the in-mold foam molding.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold surface material for in-mold foam molding, and a mold for in-mold foam molding using the surface material, and more particularly, to a thermoplastic resin and other materials for the surface material. Prevents or reduces the amount of additives, increases the strength of the surface layer to increase the durability of the surface material, and eliminates the crevices of the pre-expanded particles. The present invention relates to a mold surface material capable of providing a molded body, and a mold using the same.

[0002]

2. Description of the Related Art In-mold foam moldings such as olefin resins such as polyethylene and polypropylene, and polystyrene resins are filled with these pre-expanded particles in a molding die and heated with a heating medium such as steam. It is manufactured by foam fusion. However, the surface of the molded article obtained by molding the pre-expanded particles in the mold had a crevices pattern of the pre-expanded particles, and the appearance of the molded article surface was not good. Further, in order to uniformly heat the pre-expanded particles, it is necessary to provide a large number of steam holes in the inner surface member of the mold, which not only increases the cost of the mold, but also causes traces of the steam holes on the surface of the molded body. However, the appearance of the molded article was impaired because of the remaining, and the commercial value was reduced.

In order to solve this problem, Japanese Patent Publication No.
Japanese Patent Application Publication No. 11138 discloses a method in which a metal screen is mounted on an inner wall of a mold and molded. According to this method, although the above-mentioned problems of the prior art are solved, when the metal screen is attached to the inner wall of the mold by the attachment attached to the back surface, the attachment is welded to the back surface of the surface material. When the melted metal goes around the surface layer of the screen, this welding trace remains on the screen surface, resulting in welding traces appearing on the surface of the molded product and impairing the appearance.In addition, when screwing or bolting the metal screen from the surface In this case, the heads of the screws and bolts are transferred to the surface of the molded body, which also impairs the appearance of the molded body. Furthermore, in this method, when only one metal screen is used as the surface material, the strength when the metal screen is attached to the mold is weak, and the screen peels off at the end of the mold or the like. There is also a problem that it is not easy to attach to a mold because the material is thin. For this reason, the above method has not been put to practical use until now.

Therefore, in order to solve the problem that the metal screen is left attached to the mold in the above-mentioned method and to obtain a molded article having a good appearance, Japanese Patent Application Laid-Open Nos. H08-142061 and H08-142092. In the publication, a method is proposed in which a mold surface material made of a plurality of porous metal plates and made of a sintered body having pores through which a heating medium passes is molded using a mold attached to the mold inner wall. ing. According to this method, the problem that the trace of attachment of the metal screen to the mold remains can be solved.

[0005]

However, in this method, since a wire mesh or a punching metal as a porous metal plate is superimposed and mounted as a surface material, it adheres to a part of the thermoplastic resin or the resin. Part of the additive enters and adheres to the gaps in the wire mesh, etc., and grows as the molding is repeated.As a result, the gaps in the mesh are closed to prevent the passage of steam. An irregular pattern different from that of a metal mesh is developed, which causes a new problem of impairing the appearance. Therefore, the present invention further improves the above method, and provides a mold surface material for in-mold foam molding capable of providing a foam molded article having a good appearance, and a mold using the same. is there.

[0006]

In order to solve the above-mentioned problems, in the mold surface material of the present invention, a metal mesh forming a surface layer of the mold surface material or a back surface of a porous metal plate such as a punching metal is provided. By fixing the reinforcing metal plate by sintering, the gap between both the perforated metal plate and the reinforcing metal plate is significantly reduced, and the strength of the die surface material is improved by the reinforcing metal plate for durability. In addition, the process of attaching the surface material to the mold is facilitated. The reinforcing metal plate preferably has a steam passage hole at a position corresponding to the steam hole of the mold, but the steam passage hole is not necessarily provided. In addition, the mold for in-mold foam molding of the present invention has the surface material attached to all or a part of the inner surface of the mold.

[0007]

In the mold surface material of the present invention, since the porous metal plate and the reinforcing metal plate constituting the surface layer are sintered, there is little gap between the two and fine powder of the thermoplastic resin as a molding material. And the amount of fine powder of other additives adhering inside the surface layer is significantly reduced. In addition, since it is reinforced with a metal plate, there is no unevenness on the surface layer, and the appearance (surface properties) of the obtained molded body is improved. In addition, since the back surface of the surface material is formed of a metal plate, it is easy to weld a fixture for attaching to the mold, and the molten metal does not go to the surface layer, and a part of the surface layer is damaged at the time of welding. Don't worry. Further, in the case where the steam passage hole is provided in the reinforcing metal plate, the steam hole of the mold is not blocked by the reinforcing metal plate.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings, but they do not limit the present invention in any way.

FIGS. 1 and 2 show a typical embodiment of a mold surface material of the present invention. The mold surface material 1 has a reinforcing metal plate 3 fixed to the back surface of a porous metal plate (a wire mesh in the illustrated example) constituting the surface layer 2 by sintering. Attachment 4 to molding die
Is provided.

As the porous metal plate constituting the surface layer 2, a wire mesh or a punched metal can be used, but a wire mesh is more preferable because the reinforcing metal plate 3 is fixed to the back surface. In the case of a wire mesh, the pores of this wire mesh or punched metal are usually about 4 to 100 mesh, preferably 8 mesh.
About 30 mesh, in the case of punching metal,
The number of pores is preferably about 10 to 2000, preferably about 15 to 250 per cm ² . The size of the pores is selected in consideration of the particle size of the pre-expanded particles of the raw material to be used and the desired appearance of the molded article, but care should be taken as too large pore marks appear on the molded article surface. It is.

The reinforcing metal plate 3 is preferably a metal plate having a large number of holes 3a for allowing a heating medium such as water vapor to pass therethrough. It may be used, the steam passage hole 3a
Is preferably provided at a position corresponding to the steam hole provided in the mold without blocking the steam hole. The steam passage hole 3a has a diameter of about 2 to 20 mm and a diameter of about 5 to 30 mm.
mm interval, preferably about 2 to 10 mm in diameter and about 1 mm
It is desirable to provide at intervals of about 0 to 15 mm. If the vapor passage hole 3a is too large, the surface layer 2 made of a porous metal plate such as a wire mesh may be deformed. Therefore, it is necessary to determine the size of the steam passage hole 3a in consideration of the wire diameter of the wire mesh.
Depending on the shape and the mold of the molded product, for example, a heat amount that can be formed by indirect heating by steam through the reinforcing metal plate 3 of the surface material 1 is obtained, or a mold without the surface material 1 attached. In the case where the amount of heat required for forming can be obtained by steam from the steam holes provided on the surface, for example, a metal plate having no steam passage hole 3a is used as the reinforcing metal plate 3 as shown in FIG. In some cases.

The thickness of the reinforcing metal plate 3 is not particularly limited, and may be selected in consideration of the strength and workability as a mold surface material, ease of attachment to the mold, and the like. .6 ~
Those having a thickness of about 20 mm, preferably about 0.6 to 2 mm are used.

The above-mentioned mold surface material 1 is attached to the inner surface of the mold by attaching the surface material 1 to the mold surface member by welding, or by attaching to the back surface of the surface material 1 by welding or the like as shown in the figure. Suitably, the tool 4 is screwed with a nut.

As shown in FIG. 3, for example, the mounting member 4 is a rod-shaped body having a male screw portion 4a, one end of which is fixed to the back surface of the reinforcing metal plate 3 by welding. At this time, in the surface material 1 of the present invention, the fixture 4 is the reinforcing metal plate 3.
Therefore, even in the case of welding, the molten metal stays on the back surface of the reinforcing metal plate 3, so that there is no possibility that the molten metal will turn to the surface side of the surface material 1 and welding marks will appear on the surface layer 2.

Further, as shown in FIG. 4, the fixture 4 may be integrally fixed to the back surface of the reinforcing metal plate 3 by sintering.

It is desirable that the surface layer 2 of the mold surface material 1 be coated with a fluorine resin in order to improve the releasability of the molded body. Examples of the fluorine resin include a tetrafluoroethylene / hexafluoropropylene copolymer resin and a tetrafluoroethylene resin.

Next, a typical embodiment of the mold for in-mold foam molding of the present invention is shown in FIG. The mold 10 includes a core mold 11 and a cavity mold 12, and the core mold 11
Mold inner surface 11b at the horizontal portion of the mold inner surface member 11a
The mold surface material 1 of the present invention is attached to the mounting member 4, the nut 13, and the bolt 14 provided on the back surface. In the figure, reference numeral 15 denotes a steam hole, which is formed in the mold inner surface member 11a of the core mold 11 and the mold inner surface member 12a of the cavity mold 12 which form the molding space 16 in large numbers.

Further, in FIG. 5, the edge E indicated by an arrow is a relatively inconspicuous portion of the molded body, so that a clean edge may be provided as needed, but other edges are notable. It is desirable to make the edge easy and beautiful. Therefore, these edge portions are attached so that a part of the mold surface material 1 is laid (or bite) into the mold inner surface member 11a. When there is an inclined surface close to a horizontal plane on the mold inner surface 11b,
Since the inclined surface also affects the appearance of the molded body, it is preferable to attach the die surface material 1. Mold surface material 1
Similarly to the surface layer 2 described above, it is preferable that the inner surface of the mold to which the surface material 1 is not attached is also coated with a fluororesin.

The foamed synthetic resin used for molding with the mold for in-mold foam molding of the present invention includes polyethylene, polyethylene, and the like.
Polyolefin resins such as polypropylene, copolymers (random or block) of these monomers and other α-olefins, or polystyrene resins are exemplified.

[0020]

【Example】

(Example 1) As a mold surface material, one having the configuration shown in Fig. 1 was used. The mold surface material 1 has a thickness of 2 m as a reinforcing metal plate on the back surface of a surface layer 2 made of a single 16 mesh wire mesh.
The stainless steel plate 3 is fixed by sintering, and an attachment (bolt) 4 is provided on the back surface of the stainless steel plate 3 by welding. This surface material 1 is applied to the inner surface 11b of the inner surface member 11a of the core mold 11 in the mold 10 shown in FIG.
And fixed with nuts 13 and bolts 14. Holes of about 4 mmφ are formed in the stainless steel plate 3 as steam passage holes 3 a at intervals of about 20 mm. Further, the surface layer 2 of the surface material 1 was coated with a tetrafluoroethylene / hexafluoropropylene copolymer resin. Mold 1 other than surface material 1
0 was also coated with a tetrafluoroethylene / hexafluoropropylene copolymer resin. Next, polyolefin-based resin pre-expanded particles “Eperan PP (manufactured by Kanegafuchi Chemical Co., Ltd., expansion ratio: 30 times)” are placed in a pressure vessel in advance, and the internal pressure is increased to about 1.9 kg / cm ² by vapor pressure. The applied material was filled in the molding space 16 of the mold 10 and molded up to 300 shots at a heating maximum vapor pressure of about 3.5 kg / cm ² . As a result, a mesh pattern of a 16-mesh wire mesh was transferred to the surface of the obtained molded body, and the turtle pattern and traces of steam holes of the pre-expanded particles were not conspicuous, and had a beautiful appearance. No fine powder of the thermoplastic resin or additive was adhered.

(Example 2) As a mold surface material, one having the structure shown in FIG. 2 was used. The mold surface material 1 is made of a stainless steel plate having a thickness of 2 mm and fixed to the back of a surface layer 2 of a single 16 mesh wire mesh by sintering a reinforcing metal plate 3 having no vapor passage hole. The surface layer 2 is coated with the same fluorine-based resin as in the first embodiment, and is attached to the inner surface of the mold 10 in the same manner as in the first embodiment by using the fixture 4, the nut 13, and the bolt 14 on the back surface of the reinforcing metal plate 3. And stuck. Next, polyolefin-based resin pre-expanded particles “Eperan PP (manufactured by Kaneka Chemical Co., Ltd., expansion ratio: 30 times)” in Example 1
In the same manner as described above, a mold having an internal pressure of about 2.0 kg / cm ² was charged into the molding space 16 of the mold 10 and molded under the following conditions. On the other hand, heating: 1.2 Kgf / cm ² Heat retention: 5 seconds Heat retention: 5 seconds Pre-cooling: 3 seconds Vacuum: 550 mmHg Water cooling: 100 seconds Double-sided heating: 3.5 kgf / cm ² Cooling: 10 seconds The molded product had a beautiful appearance in which a 16-mesh wire mesh pattern was transferred to the surface of the molded product, and the crevices of the expanded particles and the traces of the vapor holes were hardly noticeable.

(Comparative Example 1) As a mold surface material, one having the structure shown in FIG. 6 was used. The mold surface material 1 ′ has a surface layer portion of a sintered body 2 ′ composed of three 16-mesh wire meshes 2 a to 2 c coated with the same fluororesin as in Example 1, and a mounting member 4 provided on the back surface. . This surface material 1 ′ was fixed to the inner surface of the mold 10 in the same manner as in Example 1. Next, polyolefin-based resin pre-expanded particles “Eperan PP (manufactured by Kaneka Chemical Co., Ltd., expansion ratio: 30 times)” in Example 1
In the same manner as in the above, a material having an internal pressure of about 1.9 kg / cm ² was charged into the molding space 16 of the mold 10 and molded to 300 shots at a heating maximum steam pressure of about 3.5 kg / cm ² . . The mesh pattern of the 16-mesh wire mesh was transferred to the surface of the obtained molded product, and the pre-expanded particles had a beautiful appearance with no noticeable turtle pattern or vapor holes. However, near 300 shots, fine powder of the thermoplastic resin and the like adhered to the inside of the wire mesh of the sintered body 2 ′ constituting the surface layer grew, and a portion of the mesh was closed to prevent the passage of steam, The mesh pattern was not transferred to the surface of that portion, and a difference in unevenness from the other surface occurred, resulting in impaired appearance of the molded article.

(Comparative Example 2) As a mold surface material, one having the structure shown in FIG. 7 was used. The mold surface material 1 ″ is formed by coating the surface layer of a surface layer 2 ″ made of one 16-mesh wire mesh with the same fluorine-based resin as in Example 1, and mounting the fixture 4 on the back surface.
Is provided. This surface material 1 ″ was fixed to the inner surface of the mold 10 in the same manner as in Example 1. Next, the polyolefin resin pre-expanded particles “Eperan PP (manufactured by Kaneka Chemical Co., Ltd., expansion ratio: 30 times) )) Was applied in the same manner as in Example 1 to give a forming internal pressure of about 1.9 kg / cm ^2, which was filled into the molding space 16 of the mold 10 and heated to a maximum vapor pressure of about 3.5 kg / cm ^2. To form up to 300 shots.
The mesh pattern of the 16-mesh wire mesh was transferred to the surface of the obtained molded body, but due to the deformation of the surface layer 2 ″, due to the wave pattern and the growth of fine powder of thermoplastic resin or the like attached to a part of the surface layer, 300 μm. From the vicinity of the shot, irregularities other than the mesh pattern appeared on the surface of the molded body, and the appearance of the molded body was significantly impaired.

[0024]

The mold surface material for in-mold foam molding according to the present invention has a reinforcing metal plate fixed to the back surface of one surface layer made of a porous metal plate by sintering. The drawback is that clogging due to the adhesion of raw resin and additives to the surface layer due to fine powder can be prevented, the pattern of the surface layer is stably transferred to the surface of the molded product, and the pattern of the pre-expanded beads is inconspicuous. A molded article having a beautiful appearance is obtained. Also, even if the fine powder adheres, the amount of the fine powder is small, the fine powder can be easily removed, and the maintenance of the mold becomes easy.
Further, the strength of the mold surface material is increased by the reinforcing metal plate on the back surface, and troubles such as turning up of a perforated metal plate such as a wire mesh or a punching metal constituting the surface layer are reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment of a mold surface material for in-mold foam molding of the present invention.

FIG. 2 is a sectional view showing another embodiment of the mold surface material of the present invention.

FIG. 3 is a cross-sectional view of a main part showing a structural example of a fixture for a mold surface material.

FIG. 4 is a cross-sectional view of a main part showing another structural example of a fixture for a mold surface material.

FIG. 5 is a sectional view showing an embodiment of a mold for in-mold foam molding of the present invention.

FIG. 6 is a cross-sectional view showing a conventional mold surface material used in a comparative example.

FIG. 7 is a sectional view showing another conventional mold surface material used in the comparative example.

[Explanation of symbols]

 1: Mold surface material 2: Surface layer 3: Reinforcement metal plate 3a: Vapor passage hole 4: Mounting tool 10: Molding die 11: Core die 11a: Die inner surface member 11b: Die inner surface 12 : Cavity mold 13: Nut 14: Bolt 15: Steam hole 16: Molding space E: Edge

Claims (8)

[Claims] 1. A reinforcing metal plate is fixed to the back surface of a surface layer made of a porous metal plate by sintering, and a steam passage hole is provided in the reinforcing metal plate at a position corresponding to a steam hole provided in a mold. Mold surface material for in-mold foam molding. 2. An in-mold foam molding die surface material obtained by fixing a reinforcing metal plate having no vapor passage hole on the back surface of a surface layer made of a porous metal plate by sintering. 3. The mold surface material for in-mold foam molding according to claim 1, wherein an attachment to the mold is provided on the back surface of the reinforcing metal plate. 4. The foam molding die surface material according to claim 1, wherein the porous metal plate is a metal mesh. 5. The mold surface material for in-mold foam molding according to claim 1, wherein the surface layer is coated with a fluororesin. 6. A mold for in-mold foam molding, wherein the mold surface material according to any one of claims 1 to 5 is attached to all or a part of the mold inner surface. 7. The mold surface material is attached to the inner surface of the mold via a fixture provided on the back surface of the reinforcing metal plate.
The in-mold foaming mold according to the above. 8. The mold for in-mold foam molding according to claim 6, wherein the mold surface material is attached such that an end thereof is laid or bitten under the mold inner surface member. .