JPS5921297B2 - Manufacturing method of resin molded product with wood grain pattern - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a thermoplastic resin molded article having a wood grain pattern.

Conventionally, granular thermoplastic resin particles or powder that serve as a base material have been added to granular thermoplastic resin particles that are the same or different from the base resin and colored darker or different than the base resin (hereinafter referred to as color pellets). It is well known that a resin molded product having a wood grain pattern can be produced by extrusion molding by adding color pellets (referred to as ) or extrusion molding by charging only color pellets from the vent hole of an extruder.

However, in the conventionally known methods, the wood grain pattern simply utilizes the flow inside the extruder, so it is not possible to change the pattern deviation at will.

This can be clearly seen from the following.

That is, this method, which was separately invented by the present inventors and others, makes wood grain patterns appear on the surface of an extruded product with a desired size and number. Extrusion molding is performed by attaching a flow regulating plate having at least one slit along the outer edge of the flow path to the flow path.

An example of this flow regulating plate is shown in FIG. 10, and an example of another flow regulating plate is shown in FIG.

In the figure, 11 is a flow regulating plate, 12 is a slit provided in the flow regulating plate, and 13 is a small circular hole normally provided in a breaker plate for rectifying the flow and generating back pressure in the cylinder.

That is, what is shown in FIG. 10 is a flow regulating plate that also serves as a breaker plate, and is installed in the same manner and at the same position as a normal breaker plate.

The flow regulating plate shown in FIG. 11 is installed separately from the breaker plate at an appropriate location in the resin flow path from the cylinder head to the Guiland inlet in a direction perpendicular to the resin flow.

When a sheet having a wood grain pattern is extruded using the flow control plate shown in FIG. 10, since there is only one slit, the wood grain pattern shown in a and l of FIG. 1 is obtained.

When a sheet is similarly extruded using the flow control plate shown in FIG. 11, three wood grain patterns appear on the sheet surface because there are three slits.

If extrusion molding is carried out using such a flow regulating plate, the problem of uneven wood grain pattern in extrusion molding will be easier to understand. I will explain this in case it happens.

However, as mentioned above, in the conventionally known methods, the wood grain pattern simply utilizes the flow within the extruder, and therefore the deflection of the pattern, that is, the bias cannot be changed arbitrarily.

If the resin ideally exhibits a precise flow pattern in the extruder, a wood grain pattern like that shown in Figure 1a would be obtained, but in reality, in many cases, the wood grain pattern, for example, as shown in Figure 1 b, would be obtained. The pattern is usually biased to one side.

This is thought to be due to the eccentricity of the screw of the extruder, the clearance between the screw and the barrel, and the clearance between the screws in the case of a multi-screw extruder.

In normal extrusion molding, these slight deviations do not pose a problem, but they become a fatal problem when a flow pattern of the resin is used to form a wood grain pattern.

In other words, if the patterns are inconsistent depending on the extruder, or even if the same extruder has a pattern that changes after repair due to trouble, commercialization will be hindered.

In view of the current situation, the inventors of the present invention have completed the present invention after repeated studies to correct the eccentricity of the wood grain pattern in extrusion molded products.

In manufacturing an extrusion molded product with a wood grain pattern from a thermoplastic resin, the present invention not only displaces the wood grain pattern appearing on the surface of the molded product at will, but also corrects the bias caused by the extruder itself. Furthermore, the purpose is to provide a method for making a wood grain pattern appear in a desired position, and its gist is to mix a base resin and a resin of a different color from this resin, and heat extrude the mixture. In the method for manufacturing a molded product having a wood grain pattern, a flow regulating plate having at least one slit and a twisting blade are arranged in parallel at the mouth inlet of the extruder along the outer edge of the resin flow path, and the above-mentioned method is provided. The present invention resides in a method for producing a thermoplastic resin molded article having a wood grain pattern, characterized in that the flow direction of the wood grain pattern produced by extrusion of a mixed resin is adjusted by the above-mentioned twisting blade.

Hereinafter, the present invention will be explained in detail with reference to the accompanying drawings.

In the method of the present invention, any conventionally known type of extrusion molding machine can be used.

A flow regulating plate having at least one slit and a twisting blade are arranged in parallel at the mouthpiece inlet of the extruder (in a specific example, between the barrel and the mouthpiece) along the outer edge of the resin flow path.

Specifically, this flow regulating plate may have a structure as shown in FIG. 10 or FIG. 11 described above.

The above-mentioned twisting vanes are arranged in parallel with the above-mentioned flow regulating plate on the downstream side of the resin flow, but these torsion vanes are shaped like twisted flat plates. In other words, it has a shape that is twisted in the direction of rotation of the clock's hands, and FIG. 3 shows the twisting blade 1 being inserted into the inner wall of the barrel 2 at an appropriate location between the barrel 2 and the mouthpiece. FIG.

The breaker plate is usually located closer to the barrel than the torsion vanes.

In Figure 2, the edges in contact with the flow of resin are made angular to make it easier to understand, but in general, they are curved to eliminate areas where the resin stagnates, and they are also streamlined over the entire surface to reduce the resistance of the resin flow. It is better to do so.

In addition, although the blade shown in Fig. 2 has twisted blades twisted to the right, it is of course possible to use blades twisted in the opposite direction, that is, to the left.
If this is used, the woodgrain pattern will be biased to the opposite side compared to when using twisted root blades twisted to the right.

Next, the twisting angle of the twisting blade used in the method of the present invention will be explained.

Figure 4 is a drawing for explaining the twist angle of the simplest type of torsion blade, in which figure a is a perspective view of a flat plate before twisting, and figure b is a figure with the center axis of the torsion blade made from this flat plate. It is a front schematic view seen from the direction of l.

In the figures, A-D, A'-D', 0, 0' are the symbols to indicate the corner positions and center positions of the flat plate and the torsion blade, respectively, and the flat plate in figure a is the central axis l. is twisted around to obtain what is shown in figure b, AC and A/c
The angle θ1 formed with / is the twisting angle of the twisting blade.

To explain the action of the installed twisting blades, in Figure 5, figure a shows the flow of resin in the extruder barrel and mouth in the case where the twisting blades are not installed, and figure b shows the breaker of the same extruder. - This is a drawing showing the flow of resin in the cap when twisting blades are installed between the plate (note: one that has a flow adjustment effect as shown in FIG. 10) and the cap.

In the figure, 1 is the torsion blade, 1' is a side view of the torsion blade 1, 3 is the molten resin in the barrel, 3' is the wood grain pattern part of the resin 3, 4 is the breaker plate, and 5 is the molten part in the mouthpiece. resin, 5' is the wood grain pattern part in the molten resin 5,
6 is the molten resin in the mouthpiece when the torsion blade 1 is provided, 6
' is a wood grain pattern portion in the molten resin 6.

In Fig. 5a, in the screw head section indicated by 3,
The influence of screw rotation is strong, and the pattern is biased to one side due to the eccentricity of the screw, the gap in the clearance between the screw and the barrel, etc., and the line F' connecting the vertices of the wood grain pattern is inclined at an angle with the center line F.

In Figure a, after passing through the breaker plate 4, there is no effect of screw rotation, and the lines connecting the vertices of the wood grain pattern have no inclination, but are biased to one side from the center line.

However, as shown in Figure b, when inserting a twisting blade (twisted in the right direction) between the breaker plate 4 and the base according to the method of the present invention, the point connecting the vertices of the wood grain pattern is centered. approach the line.

In other words, as mentioned above, the flow of molten resin that is biased due to the eccentricity of the screw is twisted back by the twisting blades,
The pattern will be symmetrical.

By utilizing the action of the twisting blades, the position of the wood grain pattern can be changed at will by appropriately changing the twisting direction and twisting angle of the twisting blades.

Furthermore, it is not essential that the torsion blades be installed horizontally as shown in Figure 3; they may be installed at an angle, but it is necessary to fix the torsion blades so that they do not rotate in the circumferential direction of the barrel 2. It is.

The above description has been made regarding the case where a flow regulating plate as shown in FIG. 10 is installed in the molten resin flow path of the extruder.

The base resin and color pellet resin used in the method of the present invention may be the same or different, and such resins include styrene resins (e.g. polystyrene, rubber-modified polystyrene, ABS resin, etc.), vinyl resins (vinyl chloride resin, vinyl chloride copolymer resin, etc.), polyolefin (polyethylene, polypropylene, etc.), acrylic resin (methyl methacrylate resin, methyl acrylate resin, etc.)
Examples include.

Next, the present invention will be explained in detail.

In these Examples, a flow regulating plate shown in FIG. 10 was used as a breaker plate of the extruder.

Example 1 100 parts of pale yellow vinyl chloride resin (parts by weight, same below)
was fed into the hopper of the extruder from the vent hole at a ratio of 3 parts of brown methyl methacrylate resin color pellets, and a plate with a thickness of 20 mm and a width of 90 mm was extruded, as shown in Figure 6 a. A wood grain pattern was obtained.

The line (dotted line) connecting the vertices of the wood grain pattern is offset about 35 degrees to the left from the center line when viewed from the extruder.

Next, using the same extruder, a twisting blade twisted 20 degrees to the right was installed between the flow adjustment plate/breaker plate and the mouthpiece inlet, and extrusion molding was performed, resulting in a symmetrical wood grain as shown in Figure b. A pattern was obtained.

Example 2 100 parts of brown polystyrene was fed into a hopper at a ratio of 5 parts of white ABS resin color pellets from the vent, and a sheet with a thickness of 200 μm and a width of 600 mm was extruded, as shown in Figure 7a. A wood grain pattern was obtained.

The line connecting the vertices of the wood grain pattern was deviated approximately 150 degrees to the right from the center line when viewed from the extruder.

Next, using the same extruder, a twisting blade twisted 10 degrees to the left was installed between the flow adjustment plate/breaker plate and the mouthpiece inlet, and as a result, a symmetrical wood grain was formed as shown in Figure b. A pattern was obtained.

Example 3 100 parts of white polypropylene was fed into a hopper at a ratio of 3 parts of black polyethylene to the hopper, and a plate having a thickness of 10 mm and a width of 200 mm was extruded.
A pattern as shown in (a) was obtained.

The line connecting the vertices of this wood grain pattern, viewed from the extruder,
It was offset about 80 mw to the left from the center line.

When using the same extruder and extruding with a twisting blade twisted 20° to the left between the flow adjustment plate/breaker plate and the mouthpiece inlet, the extrusion was even more biased to the left as shown in Figure b. A pattern was obtained.

Example 4 100 parts of pale yellow vinyl chloride resin was fed into a hopper and 2 parts of brown vinyl chloride resin color pellets were fed from the vent hole to extrude a deck material with a wall thickness of 2.5 mm and a width of 1807 nm. As a result, a wood grain pattern as shown in FIG. 9a was obtained.

The line connecting the vertices of the wood grain pattern was offset about 60 degrees to the left from the center line when viewed from the extruder.

Next, using the same extruder, a twisting blade twisted 15 degrees to the right was installed between the flow adjustment plate/breaker plate and the mouthpiece inlet, and extrusion was performed, resulting in a symmetrical pattern as shown in Figure b. Obtained.

As described above, according to the present invention, various wood grain patterns can be created by changing the number, size, and position of the slits in the flow regulating plate having at least one slit hole along the outer edge of the resin flow path. In addition, since twisting blades are arranged in parallel to this flow adjustment plate, it is possible to easily and at will adjust the deviation of the wood grain pattern revealed by the flow adjustment plate. It is something that can be done.

It should be noted that the above description shows preferred examples of the method of the present invention, and the present invention is not limited thereto, but is restricted only by the scope of the claims.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram for explaining the pattern produced when a wood grain pattern is produced by extrusion molding, FIG. 2 is a perspective view illustrating the basic form of the torsion blade used in the method of the present invention, and FIG. A front view showing the blades attached to the extruder, Figure 4 is an explanatory diagram for explaining the twist angle of the twisted blades, and Figure 5 is the screw head and mouthpiece of the extruder when extruding a woodgrain pattern molded product. 6 to 9 are diagrams showing the displacement results of the wood grain pattern when no twisting blades are provided and when twisting blades are installed according to the method of the present invention, 10 and 11 are front views of examples of flow baffle plates used in the method of the present invention. In the figure, 1 is a twisting blade, 2 is a barrel, 3 is a molten resin near the screw head of the extruder, 4 is a breaker plate, 5 and 6 are molten resin in the mouthpiece, 11 is a flow adjustment plate, and 12 is a flow adjustment This is a slit in the board.

Claims (1)

[Claims] 1 In a method of manufacturing a molded product having a wood grain pattern by mixing a base resin and a resin of a different color from this resin and heating and extruding the mixture, a molded product having a wood grain pattern is produced by mixing a base resin and a resin having a different color from this resin, and by heating and extruding the mixture. A thermoplastic having a wood grain pattern, characterized in that a flow regulating plate having at least one slit hole and a twisting blade are arranged in parallel, and the flow direction of the wood grain pattern produced by extrusion of the mixed resin is adjusted by the twisting blade. Manufacturing method for resin molded products.