JP3596927B2 - Method for producing foam molded article having design pattern - Google Patents

Description

[0001]
[Industrial applications]
The present invention relates to a method for producing a foamed molded article having a designable surface, and more specifically, to provide a designable pattern on an easily visible portion of the surface of the foamed molded article, and to form a foamed melt of pre-expanded particles appearing in the portion. The present invention relates to a method for producing a foamed molded article having a good appearance in which a turtle pattern caused by wearing is eliminated.
[0002]
[Prior art]
In a conventional method for producing a foamed molded article, pre-expanded particles are filled in a molding space defined by an inner wall of a molding die, and the pre-expanded particles are heated and fused by a heating medium such as steam. Thus, a foam molded article is formed.
However, on the surface of the obtained foamed molded article, not only a turtle pattern due to foam fusion of the pre-expanded particles appears, but also marks of steam holes, hot air holes, extrusion pins for mold release, etc. remain, and foam molding is performed. There is a problem that the appearance of the body is impaired and the commercial value is reduced.
[0003]
In addition, 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 takes time and effort in manufacturing a mold and causes an increase in cost.
In order to solve such a problem, Japanese Patent Publication No. 63-11138 proposes a method of manufacturing a foamed molded article in which a metal screen is molded using a mold mounted on the entire wall surface in a molding space. I have.
[0004]
[Problems to be solved by the invention]
However, in the manufacturing method described in the above-mentioned publication, among the above-mentioned screens, the screen mounted on the wall surface substantially parallel to the mold opening direction only makes it difficult to release the foam molded article due to unevenness of the surface. However, if the mold is forcibly released, the design pattern transferred from the screen to the surface of the foamed molded article may be broken in some cases, thereby deteriorating the appearance and significantly reducing the commercial value.
In addition, for example, when a fixture such as a bolt is welded to a screen, and the fixture is mounted on a mold wall surface through the fixture, molten metal turns around the screen surface. You will lose.
An object of the present invention is to improve the production method described in the above publication and to provide a production method capable of easily molding a foam molded article having a design surface.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the method for producing a foamed molded article having a design surface according to the present invention comprises a preliminary molding method in a molding space defined by an inner wall of a molding die including a core die and a cavity die. Filling the foamed particles, in the method for producing a foamed molded article by heating the pre-expanded particles by a heating medium and performing foam fusion, to form a foamed molded body, comprising a sintered body of a plurality of porous metal plates, A mold surface material that allows the passage of the heating medium is mounted on only a wall surface substantially perpendicular to the mold opening direction in the molding space to form a foam molded article.
The porous metal plate is preferably a wire mesh or a punched metal.
[0006]
[Action]
In the manufacturing method of the present invention, since the foam molding is molded by mounting the mold surface material only on the wall surface substantially perpendicular to the mold opening direction in the molding space, the surface of the mold surface material The unevenness does not make the mold release of the foam molded article difficult. Here, the wall surface substantially perpendicular to the mold opening direction is a wall surface having an inclination angle in the range of about 75 to 105 degrees with respect to the mold opening direction, in other words, a horizontal plane and an inclination angle with respect to the horizontal plane. Refers to a gentle slope up to about 15 degrees.
As a result of the above, the design pattern transferred from the mold surface material to the surface of the foamed molded product is not damaged during the release, remains in a perfect state after the release, and has a beautiful appearance. A foam molded article can be obtained.
[0007]
【Example】
As the foamed synthetic resin used in the present invention, polyethylene, polypropylene, polyolefin resins such as copolymers (random or block) of these monomers and other α-olefins, and polystyrene resins are preferably used.
Further, in the foam molded article produced by the method of the present invention, the design of the mold surface material is transferred to a substantially horizontal portion of the molded article, and the design is not substantially transferred to the vertical portion. The portion is easy to see, and the vertical portion is hard to see and becomes more difficult to store the product, and is suitable for various containers for housing the product and the like, in particular, case interior materials.
[0008]
An embodiment of the present invention will be described below with reference to FIGS.
FIG. 1 is a schematic cross-sectional view showing an example of an apparatus used to carry out the method of the present invention. The mold shown in FIGS. 1 shows an embodiment of the present invention.
This mold comprises a core mold 21 and a cavity mold 22, as shown, and defines a molding space 25 between the inner walls 23, 24 of the two molds 21, 22. Both inner walls 23 and 24 have a large number of steam holes 26 for supplying a heating medium such as steam.
[0009]
First, the mold surface material 27 is attached to only the wall surface substantially perpendicular to the mold opening direction (the direction of arrow A) on the inner wall 23 of the core mold 21. The wall surface substantially perpendicular to the mold opening direction is, as described above, a wall surface having an inclination angle in the range of about 75 to 105 degrees with respect to the mold opening direction, in other words, a horizontal plane and a horizontal plane. Means a gentle slope up to about 15 degrees. If the inclined surface exceeds the above range, it is difficult to release the mold, and at the time of release, the transferred concavo-convex pattern is impaired, and a molded article with a beautiful appearance cannot be obtained.
[0010]
The mold surface material 27 is obtained by sintering and integrating a plurality of perforated metal plates such as a wire mesh or a punched metal, and allows passage of a heating medium such as steam or hot air. If the number of perforated metal plates is too large, the production efficiency deteriorates and the cost becomes high. The mesh of the wire mesh is about 4 to 100 mesh, preferably about 10 to 30 mesh, and the degree of perforation of the perforations of the perforated metal is about 10 to 2000, preferably about 15 to 250 per cm ^2. Good. If the degree of perforation of the meshes and pores is too large, traces thereof appear on the foamed molded article, and if it is too small, clogging occurs, and it becomes difficult for the pre-expanded particles 19 to disappear. Further, the surface layer portion of the mold surface material 27 that is in contact with the foam molded body may be a wire mesh or a punched metal, but the wire mesh is better in that the turtle pattern 19 can be effectively erased. It is not necessary that the metal mesh and the punching metal constituting the surface layer portion and the lower layer portion have the same mesh or the same perforation degree. The surface layer is preferably coated with a fluororesin for mold release.
[0011]
In order to attach the mold surface material 27 to the inner wall 23, a mounting tool 28 such as a bolt is welded to the back surface of the mold surface material 27, and the mounting tool 28 is inserted into a mounting hole 29 provided in the inner wall 23 to form a nut or the like. Is tightened by the fastener 20. If necessary, a screw 21 or the like may be used in combination. Since the mold surface material 27 is a sintered body, the welding of the fixture 28 is fixed to the lower layer of the mold surface material 27, so that the welding can be performed so that no trace of welding appears on the surface of the surface layer portion. Further, the fixture 28 is welded in advance to the porous metal plate constituting the lower layer or the back surface of the mold surface material 27, and then the porous metal plate and the porous metal plate constituting the surface layer or the upper layer are sintered. By integrating them, it is possible to completely prevent welding traces from appearing on the surface layer portion and attach the fixture 28 to the mold surface material 27.
[0012]
With the mold surface material 27 attached to the inner wall 23 as described above, the pre-expanded particles are filled into the molding space 25. When the filling is completed, the molds 21 and 22 are closed, and steam is supplied from the steam hole 26 into the molding space 25 to heat the pre-expanded particles. At this time, the pores on the back surface of the mold surface material 27 are partially closed by welding of the fixture 28, but the pores from the upper layer portion to the surface are not closed, so that the passage of water vapor does not occur. Almost no inhibition. The pre-expanded particles are foamed and fused by heating to form the interior material 13.
[0013]
Next, after cooling, the molds 21 and 22 are opened in the direction of arrow A, and the interior material 13 is released. At the time of mold release, since the mold surface material 27 is mounted only on the wall surface substantially perpendicular to the mold opening direction in the molding space 25, irregularities on the surface of the mold surface material 27 The mold release is not made difficult. Therefore, the mesh pattern of the wire mesh or the pore pattern of the punched metal transferred from the mold surface material 27 to the substantially horizontal surface of the interior material 13 is not removed during the mold release. It is not damaged and remains in a perfect state even after the release, resulting in a beautiful design pattern 18.
[0014]
As shown in FIGS. 3 and 4, the interior material 13 thus obtained not only has the design pattern 18 on the substantially horizontal surface thereof, but also has the pattern 19 of the pre-expanded particles and the steam pattern 19 appearing on the surface. Since the holes 26 are erased after the holes 26 and no trace of welding of the fixture 28 is recognized, the appearance is beautiful and the commercial value is high.
[0015]
FIG. 2 shows a state in which the interior material 13 is fitted inside the case exterior material 12. The lid 11 and the exterior material 12 constitute a box made of a hard synthetic resin, metal, wood, paper, or the like.
[0016]
The interior material 13 is for fixing the product or the like by filling a gap formed around the product or the like housed in the case. On the upper surface of the interior material 13, a concave-shaped accommodation portion for accommodating the product or the like is provided. 14 is open, and a step portion 15 is formed inside the accommodating portion 14. The upper end surface of the peripheral wall 16 and the upper surface of the bottom plate 17 are horizontal surfaces, and the upper surface of the step portion 15 is a gently inclined surface having an inclination angle of up to about 15 degrees. A mesh pattern of a wire mesh or a pore pattern of a punched metal is transferred as a design pattern 18 by the above-described manufacturing method.
[0017]
In addition, since the design pattern 18 is not provided on the inner and outer vertical surfaces of the peripheral wall 16, the vertical surface of the step portion 15, and the lower surface of the bottom plate 17, a turtle pattern 19 of the pre-expanded particles foamed and fused appears. .
[0018]
In the case having the above-described configuration, when the lid 11 is opened in a state in which a product or the like is stored in the storage portion 14, the design pattern 18 is provided on the upper end surface of the peripheral wall 16 that is easily visible, so that the appearance is beautiful. The product value of products etc. increases. At this time, since the inner vertical surface of the housing portion 14 is hidden by a product or the like, the turtle pattern 19 existing on the inner vertical surface is not visible from the outside, and does not impair the appearance.
[0019]
In addition, since the outer peripheral surface of the peripheral wall 16 and the lower surface of the bottom plate 17 are completely hidden by the exterior material 12, the tortoiseshell pattern 19 existing on those surfaces has no effect on the appearance.
Also, when a product or the like is taken out of the housing portion 14, an inner vertical surface of the housing portion 14 appears to the outside. However, since the design pattern 18 is provided on the bottom plate 17 and the upper surface of the step portion 15 which are easily visible, The vertical planes are not so noticeable as the horizontal planes, and there is no risk that the appearance of the turtle pattern 19 on these vertical planes will significantly impair the appearance.
In the above example, the interior material is fitted only to the exterior material constituting the container body, but it goes without saying that the interior material can also be fitted to the lid if necessary.
[0020]
【The invention's effect】
As described above, according to the manufacturing method of the present invention, the mold surface material is mounted and molded only on the wall surface substantially perpendicular to the mold opening direction in the molding space. The unevenness of the surface does not make it difficult to release the foam molded article. Therefore, the design pattern transferred from the mold surface material onto the substantially horizontal surface of the foamed molded article remains in a perfect state even after the mold release of the foamed molded article, and the pre-expanded particles appearing on the face are removed. The turtle pattern and the trace of the steam hole are erased. Therefore, the obtained foam molded article has a beautiful appearance and high commercial value.
[0021]
In addition, since the mold surface material is a sintered body of a plurality of perforated metal plates, when welding the fixture to the back surface of the mold surface material, make sure that welding traces do not appear on the surface of the mold surface material. Can be welded. Therefore, it is possible to obtain a foam molded article having a good appearance in which no trace of welding of the mounting tool appears.
[0022]
Further, the heating medium is uniformly introduced into the molding space through the pores of the mold surface material, and since the introduction of the heating medium is not substantially hindered by the attachment of the fixture, it is possible to obtain a heat-sealing property without uneven heating. A good foam molded article can be obtained, and even heating can be performed without providing a large number of heating medium supply holes as in the related art, and the manufacturing cost of the mold can be reduced.
[Brief description of the drawings]
FIG. 1 is a schematic sectional view showing one embodiment of a mold used to carry out the method of the present invention.
FIG. 2 is a perspective view showing one embodiment of a case fitted with an interior material foam-formed by the manufacturing method of the present invention.
FIG. 3 is a plan view of an interior material used for the case of FIG. 2;
FIG. 4 is a sectional view taken along line III-III in FIG. 3;
[Explanation of symbols]
18 Design pattern 21 Core mold 22 Cavity mold 23 Inner wall of core mold 24 Inner wall of cavity mold 25 Molding space 27 Mold surface material

Claims (2)

The pre-expanded particles are filled in the molding space defined by the inner wall of the molding die composed of the core mold and the cavity mold, and the pre-expanded particles are heated by a heating medium to foam and fuse. In the method for producing a foamed molded article for molding a molded article, a mold surface material made of a sintered body of a plurality of porous metal plates and allowing the heating medium to pass therethrough in a mold opening direction in the molding space. A method for producing a foamed molded article having a design pattern, wherein the foamed molded article is molded by being mounted on only a substantially vertical wall surface. The method according to claim 1, wherein the perforated metal plate is a metal mesh and / or a punched metal.

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