JP2002292649A - Method for manufacturing molded object - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for inexpensively manufacturing a molded object without generating hue irregularity from an aspect of appearance, for example, even if a recycled resin is used. SOLUTION: The molded object 14 is manufactured through a process for arranging a layer forming material 10 along the inner surface of the cavity 6 of a mold 60 and a process for injecting a molten resin 12 in the layer forming material 10 from an extruder.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a molded article such as a false wood.

[0002]

2. Description of the Related Art In recent years, a pile, a fence or a pillar used in a park or the like has been made of a resin molded article having a tree-like appearance or color instead of concrete or wood. . As a method for producing this type of resin molded article, for example, a push molding method in which a molten resin extruded from a molten resin extruder is injected into a cavity of a mold is known (see Japanese Patent Application Laid-Open No. 2001-30271). ).

In the extrusion molding method, an extruder is used to inject a resin into a mold, so that a relatively high-viscosity molten resin is produced in a larger amount than injection molding in which a completely melted low-viscosity resin is injected. Can be injected. According to the indentation molding method, even a resin having a relatively high viscosity and a low temperature can hardly lower the temperature as a whole, so that it is possible to transfer the shape of the mold surface (for example, uneven shape) with good reproducibility. For these reasons, it can be said that the indentation molding method is suitable for the production of large molded articles such as artificial wood.

[0004] On the other hand, from the viewpoint of environmental problems, it is desired to use recycled resin as a molding material for various molded articles. However, it is difficult to use the recycled resin as a molding material for injection molding because the resin component tends to cause unevenness in the resin component and the viscosity may not be constant even at a constant temperature.
In contrast, in extrusion molding, the allowable range of usable resin viscosity is relatively wide, and recycled resin can be used.

[0005]

However, if the recycled resin is not sufficiently separated, the molded product is likely to be uneven even by the indentation molding method. In particular, color tone unevenness in appearance becomes a problem. By adding a coloring agent such as a pigment to the recycled resin, it is possible to make the color of the molded product constant, but if the object to be molded is a large product, a large amount of the coloring agent is required, and the production cost is reduced. Tended to be higher.

Further, in order to make the appearance of the molded article beautiful, it is necessary to apply a treatment such as painting to the molded article. However, such a post-treatment is troublesome, and eventually increases the production cost. In particular, in the case of a molded article having an uneven surface such as a pseudo-wood, it is often difficult to perform a treatment such as painting because the surface is uneven.

[0007] An object of the present invention is to provide a method for manufacturing a molded article which does not cause color tone unevenness in appearance even when a recycled resin is used and which can be produced at low cost. .

[0008]

Means for Solving the Problems To achieve the above object, a method for manufacturing a molded article according to the present invention comprises a step of arranging a layer forming material along an inner surface of a cavity of a mold; And injecting a molten resin using an extruder inside the forming material.

Preferably, the layer forming material is a synthetic resin,
The sheet is selected from a woven fabric, a nonwoven fabric and a pulp.

Preferably, a pattern is formed on the outside of the layer forming material.

Preferably, irregularities such as wood grain are formed on the inner surface of the cavity of the mold.

[0012]

In the method of manufacturing a molded article according to the present invention, first, a layer forming material is arranged along the inner surface of a cavity of a mold, and a molten resin is injected inside the layer forming material using an extruder.
At this time, the layer forming material receives the pressure of the molten resin from the inside thereof, so that it spreads along the inner surface of the cavity of the mold and adheres to the molten resin inside.

According to the present invention, since the molded body is manufactured by using the indentation molding method capable of transferring the shape of the mold surface with good reproducibility, for example, if irregularities such as wood grain are formed on the inner surface of the mold in advance, such a shape can be obtained. Irregularities can be easily transferred. Moreover, since the layer forming material is disposed between the inner surface of the mold and the molten resin to be pressed, it is easy to form a beautiful uneven surface on the molded body.

According to the present invention, since the molten resin is injected into the inside of the layer forming material after the arrangement, even if a recycled resin that is insufficiently separated is used, the recycled resin is not exposed on the surface. There is no unevenness of color tone on the appearance. In addition, unevenness in physical properties when a recycled resin is used can be easily improved by the strength of the layer forming material and the like. In addition, depending on the material of the layer forming material, it is easy to impart various characteristics such as ultraviolet light resistance and oxidation resistance.

The method of the present invention can be suitably used for the production of large molded products such as artificial wood, benches, tables and the like.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments shown in the drawings.

FIG. 1 is a schematic view of an apparatus for manufacturing a molded article according to one embodiment of the present invention, and FIGS. 2A to 2F are views for explaining a method of manufacturing a molded article according to one embodiment of the present invention. 3 (A) is a cross-sectional view taken along the line IIIA-IIIA of FIG. 2 (C), and FIG. 3 (B) is a cross-sectional view taken along the line IIIB-IIIB of FIG. 2 (D).

Before explaining a method for manufacturing a molded article according to one embodiment of the present invention, first, an apparatus for manufacturing a molded article for realizing the manufacturing method will be described.

As shown in FIG. 1, the molded article manufacturing apparatus 2 according to the present embodiment has an extruder 4 and a molding machine 6, and the extruder 4 and the molding machine 6 are provided with a resin introduction pipe 8 Connected through.

As shown in FIG. 2C, the extruder 4
A single screw shaft 42 is rotatably mounted in a barrel 44. A heat medium flow passage (not shown) is provided in the barrel 44.
Are formed, and the temperature inside the barrel 44 can be adjusted. A molding material is supplied to the inside of the barrel 44 from a hopper (not shown), and the molding material is melted and kneaded by the rotation of the screw shaft 42 to become a molten resin 12 described later. To be sent out. An adapter 46 is attached to the discharge port 45 of the extruder 4 so that the flow of the molten resin 12 extruded by the screw 42 can be restricted.
The discharge side of the adapter 46 is connected to the molding machine 6 through the resin introduction pipe 8. A heater (not shown) for preventing cooling of the molten resin 12 in the resin introduction tube 8 may be mounted around the resin introduction tube 8.

The molding machine 6 has a mold 60. Mold 60
In the present embodiment, the upper mold 62 and the lower mold 64 are configured so that the upper mold 62 and the lower mold 64 are relatively freely movable toward and away from each other, and are combined with each other to form a cavity therein. 65 (see FIG. 2A). For example, irregularities such as wood grain may be formed on the inner surfaces of the molds of the upper mold 62 and the lower mold 64.
The size and shape of the mold 60 may be appropriately selected depending on the purpose.

As shown in FIG. 1, in this embodiment, the upper die 62 is driven by a pressure cylinder 66 such as a hydraulic cylinder, so that the die can be clamped and opened.

As shown in FIG. 2C, the left side of the mold 60 is closed, and the right side of the mold 60 is formed with an inlet 67 through which the molten resin is introduced. The resin inlet tube 8 is connected to the inlet 67.

Next, a method for manufacturing a molded article according to one embodiment of the present invention will be described.

First, as shown in FIG.
The layer forming material 10 is disposed between the upper mold 62 and the lower mold 64, and thereafter, the pressure cylinder 66 shown in FIG. 1 is driven, and as shown in FIGS. 2 (C) and 3 (A), By combining the upper mold 62 close to the lower mold 64, the layer forming material 10 is arranged along the inner surface of the cavity 65.

The layer forming material 10 may be arranged in any manner as long as the layer forming material 10 is pressed against the inner surface of the mold by the molten resin extruded from the extruder 4 and can be formed into the shape of the inner surface of the mold. There is no need to adhere to the inner surface.

The layer forming material 10 is not particularly limited as long as it can be formed by being pressed by a molten resin and reproducing the unevenness of the inner surface of the mold in the press molding. It is preferred that the sheet be selected.

Examples of the synthetic resin sheet include a foamed sheet, synthetic leather, synthetic paper, and a sheet containing a filler such as wood flour. The material is not particularly limited, but is preferably a polyolefin resin, a styrene resin, an acrylic resin, or the like. The thickness is preferably 0.1 to 2 mm, more preferably 0.5 to 1 mm.

The material of the woven or non-woven fiber sheet is
Preferably polyester resin, polyamide resin, polyolefin resin and the like, the weight of which is preferably 50 to
It is about 500 g / m ³ . The thickness is preferably 0.
It is about 5 to 2 mm, more preferably about 0.7 to 1.5 mm.

The pulp sheet is preferably paper,
Cork sheets and the like. The thickness is preferably 0.05
mm to 2 mm, more preferably about 0.1 to 1 mm.

Various additives such as a coloring agent, an ultraviolet absorber and an antioxidant may be added to the layer forming material 10.

Various patterns may be formed on the outer surface of the layer forming material 10 by, for example, printing, or may be colored.

Next, as shown in FIG. 2C, the extruder 4 and the mold 60 are connected by a resin introduction tube 8.

Next, as shown in FIGS. 2 (D) and 3 (B), the molten resin 12 is supplied from the extruder 4 to the cavity 6.
5 (see FIG. 2A) is injected into the inside of the layer forming material 10 arranged along the inner surface.

A molten resin 12 in which a molding material is melt-kneaded.
The type of is not particularly limited, but is preferably a polyolefin resin, a styrene resin, more preferably a polyolefin resin, further preferably a polypropylene resin or a polyethylene resin, and these may be recycled resins. Even if a recycled resin is used, according to the method of the present invention, there is no unevenness in appearance of the molded article. The molten resin 12 may contain a ground paper, a thermosetting resin ground, an FRP ground, or the like. In this case, the addition amount is preferably 200 parts by weight or less based on 100 parts by weight of the resin.

Then, as shown in FIGS. 2 (E) and 2 (F), after injecting the resin and cooling for a predetermined time, the molding machine 6
The mold 60 is opened to obtain the molded body 14.

An adhesive layer (not shown) may be formed on the contact surface between the layer forming material 10 and the molten resin 12 in advance. By forming the adhesive layer, the adhesiveness between the layer forming material 10 and the molten resin 12 is improved, and the possibility of inconvenience such as peeling when the molded body 14 is used is further reduced. The adhesive layer is not particularly limited, but a pressure-sensitive adhesive, a hot-melt adhesive, a film-like binder, or the like can be used. The thickness of the adhesive layer is preferably 30 to
It may be about 200 g / m ² .

According to the manufacturing method of the molded body 14 according to the present embodiment, the molded body is manufactured by using the press molding method capable of transferring the shape of the mold surface with good reproducibility. If formed on the inner surfaces of the lower mold 62 and the lower mold 64, such irregularities can be easily transferred. Moreover, upper die 6
2 and the inner surface of the lower mold 64 and the molten resin 12
Since the layer forming material 10 is disposed between the molded body 14 and the base member 10, a beautiful uneven surface can be formed on the molded body 14.

Further, according to the method of manufacturing the molded body 14 according to the present embodiment, the molten resin is injected into the inside of the layer-forming material 10 after the arrangement, so that even if a recycled resin which is insufficiently separated is used. The recycled resin is not exposed on the surface, and there is no unevenness of color tone in appearance.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments at all, and may be implemented in various modes without departing from the gist of the present invention. Of course.

[0041]

EXAMPLES Hereinafter, the present invention will be described based on more detailed examples, but the present invention is not limited to these examples.

Example 1 A 100 mmφ × 1 with an inner surface dug like Kunugi
After disposing a 0.5 mm thick high-density polyethylene sheet, which is toned in a substantially brown color, over the entire inner circumference of a log mold having a length of 000 mm as shown in FIGS. 2 (C) and 3 (A). The tip of the extruder was attached to the inside of the sheet after the placement. Next, the polyolefin (80% and other resin 20%) separated from the municipal general waste was melt-kneaded at a barrel temperature of 190 ° C. and a head temperature of 200 ° C. using an extruder, and injected into the sheet after being placed. Thereafter, the molded product was cooled to room temperature to obtain a molded body having beautifully formed rugged-like irregularities on the surface. The obtained molded product was subjected to a UV exposure test for 2000 hours, and no discoloration was observed.

Example 2 The inner surface of the mold was smoothed, and instead of a polyethylene sheet, a substantially birch pattern was applied to the contact surface of the mold, and a hot melt adhesive of 100 g / m ² was applied to the contact surface of the molten resin. A birch-like log was obtained in the same manner as in Example 1, except that a polymethyl methacrylate sheet having a thickness of 0.5 mm was used. The obtained molded article was subjected to the same UV exposure test as in Example 1, but no discoloration was observed.

Comparative Example 1 Polyolefin (80% and other resin 20%) separated from municipal waste without placing a sheet on the inner surface of the mold
A molded article was obtained in the same manner as in Example 1, except that a resin composition containing a brown pigment was injected into a mold. On the surface of the obtained molded body, rugged-like irregularities were formed,
Non-uniform resin flow and spots were confirmed on the surface of the molded body.
In this respect, the superiority of Example 1 was confirmed. Further, when the obtained molded article was subjected to an ultraviolet exposure test for 1000 hours, a whitening phenomenon occurred. In this respect, the superiority of Examples 1 and 2 was confirmed.

[0045]

As described above, according to the present invention, even if a recycled resin is used, for example, a molded article can be produced at low cost without causing color tone unevenness in appearance. Can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic view of an apparatus for manufacturing a molded article according to an embodiment of the present invention.

2 (A) to 2 (F) are process diagrams for explaining a method for manufacturing a molded article according to one embodiment of the present invention.

3A is a cross-sectional view taken along the line IIIA-IIIA of FIG. 2C, and FIG. 3B is a cross-sectional view taken along the line IIIB-IIIB of FIG. 2D.

[Explanation of symbols]

 2 ... Molding device manufacturing apparatus 4 ... Extruder 42 ... Single screw shaft 44 ... Barrel 45 ... Discharge port 46 ... Adapter 6 ... Molding machine 60 ... Mold 62 ... Upper mold 64 ... Lower mold 65 ... Cavity 66 ... Pressure Cylinder 67 ... Inlet 8 ... Resin introduction tube 10 ... Layer forming material 12 ... Molten resin 14 ... Molded body

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[Procedure amendment]

[Submission date] March 30, 2001 (2001.3.3)
0)

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] Figure 2

[Correction method] Change

[Correction contents]

FIG. 2

[Procedure amendment 2]

[Document name to be amended] Drawing

[Correction target item name] Figure 3

[Correction method] Change

[Correction contents]

FIG. 3

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Claims (4)

[Claims] 1. A molded article having a step of disposing a layer forming material along an inner surface of a cavity of a mold, and a step of injecting a molten resin using an extruder into the layer forming material after the disposition. Production method. 2. The method according to claim 1, wherein the layer forming material is in a sheet shape selected from a synthetic resin, a woven fabric, a nonwoven fabric, and a pulp. 3. The method according to claim 1, wherein a pattern is formed outside the layer forming material. 4. The method according to claim 1, wherein the inner surface of the cavity of the mold has irregularities.