JPS6362376B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Field of Application> The present invention relates to an apparatus for producing a single-layer blown film made of a different color or a different type of synthetic resin.

<Conventional technology> Conventionally, resins of different colors or different types are separated and guided from each extruder to an annular slit in a die.
The technique of subsequently extruding a cylindrical film through an annular slit by merging resins of different colors or different types is as follows.
For example, this technique is known in Japanese Utility Model Publication No. 49-3637 (hereinafter referred to as the first known technique) and Japanese Patent Publication No. 52-10142 (hereinafter referred to as the second known technique).

<Problems to be Solved by the Invention> When extrusion molding different colored or different types of resins like this, it is important that the merging boundary line between the different colored or different types of resins is clear and the fusion adhesive strength is high. If the boundary line is unclear, the appearance of the product will be impaired, and if the fusion adhesive strength is insufficient, it will tear from the boundary line.

In order to clarify this boundary line and increase the fusion adhesive strength, it is necessary to smoothly flow a sufficient amount of resin until the resins of different colors or types reach the confluence point.

If the flow of the resin to the confluence point is poor, the resin will stagnate and deteriorate in quality, resulting in deterioration of the fusion adhesive strength.
Furthermore, if the resin flow rate is insufficient at the merging point, sufficient merging and fusion cannot be obtained, the boundary line becomes unclear, and the fusion adhesive force becomes weak.

By the way, neither of the first and second known techniques described above satisfies the above-mentioned problems. That is, in the case of the first known technique, the molten resin extruded directly from the extruder into the valley bottoms of the mountain-shaped partition walls rises directly between the partition walls, spreads from side to side, and flows along the partition walls. Therefore, by the time the resin spreads from side to side and reaches the dividing wall, the flow velocity is reduced due to resistance, and the flow of the resin along the dividing wall becomes poor. In addition, since the resin passages between the partition walls are all gaps having the same thickness, the flow rate of the resin flowing along the partition walls is poor, and a sufficient amount of resin does not flow.

Furthermore, there is also a demand for products in which the width of different colors or different types of resins is greatly or slightly changed. The second known technique accomplishes this by changing the position of a movable separator and varying the amount of resin extruded by an extruder.

In order to vary the amount of resin extruded by this extruder, the rotational speed of the screw of the extruder is slow controlled, but in this type of case that requires delicate flow rate adjustment, it is necessary to adjust the amount of resin extruded by the extruder. It is not easy to set up.

In addition, to change the separator position, you must not only loosen and tighten the separator fixing bolts, but also remove peripheral parts such as the holding plate and slit adjustment ring.
There is a problem in that it requires troublesome assembly work, and during that time the extruder must be stopped.

The purpose of the present invention is to solve the above-mentioned conventional problems,
The object of the present invention is to provide a device that satisfies the above-mentioned problems.

<Means for Solving the Problems> The feature of the present invention for achieving the above object is to have an annular slit for extrusion molding a cylindrical film, and a plurality of resins each having a different color or type. The extruder has a plurality of resin passages introduced from the extruder, and from each resin passage to the annular slit, the slit extends and tilts in the direction of travel of the resin to separate different colors or different types of resin, and immediately before the annular slit, A synthetic resin film manufacturing apparatus is provided with a die in which a mandrel is provided with a mandrel formed with a mountain-shaped partition wall having a pointed tip for merging. A concave groove is formed along the wall, the depth of which gradually becomes shallower as it reaches the confluence of the tips of the partition walls, and each resin passage is provided with a check valve.

<Function> With the above configuration, the present invention allows the resin flowing along the partition wall to flow at a higher resin flow rate than other parts without stagnation in the groove and reach the confluence point, ensuring fusion adhesive strength and Make boundaries clear.

In addition, to change the width of different colors or different types of resin, the width can be adjusted based on the operating condition of the extruder by adjusting the opening of each check valve provided on the die. It is something.

<Examples> Examples of the present invention will be described below based on the drawings. In FIG. 1, 1 is a die, which has an annular slit 2 for extruding a single-layer cylindrical film;
It has an air inlet 3 and an air ejection hole 4 for expanding the cylindrical film extruded from the annular slit 2.

Furthermore, a first extruder 5a and a second extruder 5b are connected to the die 1. Both extruders 5a,
The resin extruded from 5b is a different color or different type of resin.

FIG. 2 is a longitudinal sectional view of the die 1, which has a first resin inlet 6 connected to the first extruder 5a and a second resin inlet 7 connected to the second extruder 5b. As shown in FIG. 3, first resin passages 8a and 8b lead from the first resin inlet 6 to the mandrel 9.
Further, second resin passages 11a and 11b are provided which connect from the second resin inlet 7 to the mandrel 9 via a branch passage 10.

As shown in FIGS. 4 to 6, the mandrel 9 separates the different color or different type of resin introduced into the mandrel 9 from the first resin passages 8a, 8b and the second resin passages 11a, 11b up to just before the annular slit 2. A mountain-shaped dividing wall 12 is formed, and the dividing wall 1
It has a structure in which two vertices a, a', b, and b' are formed at a plurality of locations around the circumference, and the apexes a, a', b, and b' are meeting points of different colors or different types of resin.

In the present invention, confluence points a, a', b, A groove 13 is formed whose depth gradually becomes shallower as it reaches b'.

Furthermore, the first resin passages 8a, 8b are provided with check valves 15a, 15b for controlling the resin flow rate, and the second resin passages 11a, 11b are also provided with similar check valves 14a, 14b. If necessary, as shown in FIG. 2, an annular groove 17 is formed on the inner peripheral surface of the film thickness adjusting ring 20 forming the annular slit 2.

Since the present invention is as described above, for example, the first
To explain the case where the resin in the extruder 5a is white and the resin in the second extruder 5b is red, the white resin flows from the first resin inlet 6 through the first resin passages 8a and 8b to the partition wall 12 of the mandrel 9. confluence point a-b,
a'-b', and the red resin is introduced from the second resin inlet into the branch passage 10 and the second resin passage 11a,
11b, the mandrel 9 is introduced between the confluence points a-a', b-b' of the dividing wall 12, and is divided until it enters the annular slit 2, and the confluence points a-a', b-
They merge and fuse to form one ring within the annular slit 2 while maintaining the interval b', and form a confluence point a as shown in Fig. 7.
The part that passed between -a' and b-b' is red film 1
6a and 16a', and the portions passing between the confluence points a-b and a'-b' are extruded into white films 16b and 16b'.

Therefore, the present invention provides the first resin passages 8a, 8.
The resin flowing along the partition wall 12 from the second resin passages 11a and 11b passes through the concave groove 13 provided along the partition wall 12 and reaches the confluence points a, a',
b, b'. As shown in FIG. 5 and FIG.
From the vicinity of b, 11a, 11b to the confluence a, a',
It has a shape in which the depth gradually becomes shallower as it reaches b and b'. Therefore, the amount of resin flowing through this groove 13 is larger than that in other parts, which improves the flow and ensures a sufficient resin flow rate at the confluence points a, a', b, and b'. Therefore, it prevents resin deterioration, improves the fusion adhesive strength of different colors or different types of resins, and makes their boundaries clear.

In addition, when adjusting the ratio of the width of the red films 16a, 16a' and the width of the white films 16b, 16b', the check valves 14a, 14b, 15a, 15b
This can be obtained by adjusting the opening degree of the In this case, the opening degree for narrowing the width is reduced, and the opening degree for widening the width is proportionally increased. Therefore, the extruders 5a and 5b remain in operation, and the check valve 14 is closed.
Width adjustment can be achieved simply by operating a, 14b, 15a, and 15b, and fine adjustments can also be made easily.

As shown in FIG. 8, the single-layer cylindrical film 16 of a different color or different kind obtained above is flattened with two parallel rows of fasteners 19 in the center, and the center between the fasteners 19 is aligned in the longitudinal direction A-A. By welding and cutting along B--B perpendicular to this, a single bag 18 having a single color and different types of films can be obtained.

<Effects of the Invention> As described above, according to the present invention, a synthetic resin film manufacturing apparatus is provided in which a mountain-shaped dividing wall is formed on the mandrel in the die, and resins of different colors or different types are merged at the tip of the dividing wall. In this configuration, concave grooves are formed on the left and right sides of the resin flow interval between each of the partition walls, the depth of which gradually becomes shallower as the resin passage runs along the partition walls to the merging point of the tips of the partition walls. The amount of resin flowing toward the point is larger than other parts, improving the flow, and the resins are merged at the merging point with a sufficient flow rate, making the merging boundary line clear and improving the fusion adhesive strength.

In addition, the resin film width between the partition walls is adjusted by controlling the opening degree of the resin passage using a check valve installed in the die, so compared to the conventional method in which the amount of resin extruded by an extruder is varied, the adjustment is easier. It is easy to operate and fine adjustments can be made easily. Further, since the adjustment can be made while the extruder is in operation, there is no adverse effect on manufacturing efficiency.

[Brief explanation of drawings]

The drawings show embodiments of the present invention.
Figure 2 is a plan view of the overall configuration, Figure 2 is a longitudinal sectional view of the die, Figure 3 is a plan view of the die, Figure 4 is a side view of the mandrel, Figure 5 is a sectional view taken along the line 4 - 6. The figures are a cross-sectional view taken along the line shown in FIG. 4, FIG. 7 is a side view of the extruded state, and FIG. 8 is a perspective view of an extruded cylindrical film made of a different color or different type of synthetic resin. 1... Dice, 2... Annular slit, 5a...
First extruder, 5b... Second extruder, 6... First resin inlet, 7... Second resin inlet, 8a, 8b...
...First resin passage, 9...Mandrel, 11a, 1
1b...Second resin passage, 12...Dividing wall, 13...
...Concave groove, 14a, 14b, 15a, 15b...Chiyoke valve, a, a', b, b'...Confluence point (apex).

Claims (1)

[Scope of Claims] 1. It has an annular slit for extrusion molding a cylindrical film, and includes a plurality of resin passages into which resins of different colors or types are respectively introduced from a plurality of extruders, and each of the resin passages A mandrel is installed inside the mandrel, which forms a mountain-shaped partition wall that spreads out and slopes in the direction of travel of the resin from to the annular slit to separate different colors or different types of resin, and has a pointed tip that joins the resin just before the annular slit. The synthetic resin film manufacturing apparatus is equipped with a die, and the resin flow gap between the respective partition walls has a resin flow gap on the left and right sides from the resin passage along the partition walls to a confluence point of the tips of the partition walls, the depth of which gradually increases. 1. An apparatus for producing a single-layer, different color or different type of synthetic resin film, characterized in that a concave groove with a shallow depth is formed, and a check valve is provided in each of the resin passages.