JP2003001692A - Flat die for manufacturing laminated film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flat die which is free from problems with known multi- layered dies such as a multi-manifold die and a feed block die, in the flat die for manufacturing a laminated film by laminating molten resin films over each other, especially provide a flat die capable of extruding two pieces of molten resin film from a position close to a vacuum molding roll, as a best-suited flat die for manufacturing a plastic expanded sheet. SOLUTION: This flat die is of such a structure that two resin flow channels (2A and 2B) and two resin manifolds (3A and 3B) are arranged side by side in a single die head (1). In addition, the die has two lips (4A and 4B) running in parallel with their individual openings formed. Especially, the openings of the two lips (4A and 4B) are positioned at different levels from each other in the discharge direction.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a flat die for producing a laminated film. Here, the "laminated film" is not limited to a film that is entirely laminated, but includes a partially laminated film such as a bubble sheet.

[0002]

2. Description of the Related Art There are various modes for producing a laminated film formed by laminating two or more layers of synthetic resin films. In the case of two layers for the sake of simplicity, they are in the molten state, just extruded from a T-die on one ready-made film, where two or more ready-made films are glued together. Another synthetic resin film is placed and fused or adhered, two films in a molten state are fused or adhered together, and two kinds of films are used inside the T-die by using a “multilayer die”. Either one is formed by laminating molten synthetic resins and extruded from one die lip. From the point of view of production efficiency, Ya is better than Ya.

Among the above, that is, the mode using the multi-layer die is further classified into a "multi-manifold" type and a "feed block" type. The former has two resin channels (2A, 2B) and manifolds (3A, 3B) in one die head (1) as shown in FIG. 1, and has one integrated lip (4). ) Is used. The latter has one manifold (3) as shown in FIG. 2, and is equipped with a facility called a “stacking plate” (5) at the upper part of the die for combining two kinds of resins introduced separately. Use a die.

Although the use of these multi-layer dies is a smart technology, it is often difficult to operate. The problem common to the two types is when starting and ending the operation of two extruders that melt-extrude different kinds of synthetic resins, and if the operation / stop timing is incorrect, one resin may flow back to the other. .
In order to prevent the problem at the time of stopping, it is sufficient to replace the contents of the two extruders with the same resin and then stop, but there is a drawback that a large amount of waste is generated.

What is the problem unique to each of the two types? First, in the multi-manifold type, since a manifold is provided for each layer, if the number of layers increases, the die head becomes larger and the weight becomes too large. It is a practical difficulty. Next, the feed block type can reduce the size of the die head and the problem of weight because the stacking plates can be stacked to form multiple layers, but since the structure does not have a manifold for each resin, the resin has very different physical properties. Means that they cannot be combined.

For example, when a "hard" resin, that is, a resin having a low fluidity, and a "soft" resin, that is, a resin having a high fluidity, are combined, each portion in the die is a laminate of molten resin having the same thickness. After being pushed out, the soft resin wraps around the outside of the hard resin,
A hard resin is thickened in the central portion, and a soft resin is thickened in the portions near both side edges to form a laminated film. Therefore, even if an attempt is made to produce a gas barrier film to form a laminate in which nylon is sandwiched between two polyethylene sheets, it is difficult to carry out with a feed block type multilayer die.

The inventors of the present invention have adhered a flat back film to a cap bottom portion of a cap film provided with a large number of caps by continuous vacuum forming of a plastic bubble sheet, that is, a film by a vacuum forming roll, by heat fusion. In a technique for producing a sheet having a large number of closed cells, a method for producing a sheet, in which a molten resin film discharged from a T-die is directly guided to a vacuum forming roll to perform the above-mentioned forming and bonding, is invented. , Have already proposed (Japanese Patent Application No. 2001-12745). In order to carry out this manufacturing method, it is necessary that the two molten resin films are extruded closely from a position close to the vacuum forming roll.

[0008]

SUMMARY OF THE INVENTION A general object of the present invention is to produce a laminated film, which is suitable for laminating molten resin films with each other with high production efficiency, and has a problem of known multilayer dies. To provide a flat die that avoids.

A particular object of the present invention is to provide two molten resin films from a position close to a vacuum forming roll, which is suitable for carrying out the above-mentioned method for producing a plastic foam sheet proposed by the inventors. It is to provide a flat die that can be extruded.

[0010]

A flat die for solving the general problems of the present invention has a structure for producing a laminated film by melt-extruding a synthetic resin as shown in the structure of a typical embodiment in FIG. It is a flat die, and two series of resin channels (2A, 2A, provided in parallel in one die head (1)
2B) and two series of resin manifolds (3A, 3B)
And a flat die having two lips (4A, 4B) running in parallel and opening separately.

A flat die which solves a specific problem of the present invention has a structure as shown in FIG.
The above-mentioned one die head (1) is provided in parallel,
In a flat die having two series of resin flow paths (2A, 2B) and two series of resin manifolds (3A, 3B), and having two lips (4A, 4B) running in parallel and opening separately, The positions where the two lips (4A, 4B) are opened are flat dies arranged with a height difference in the ejection direction indicated by the arrow. In this figure,
Reference numeral (41) indicates a lip cover that forms a lip and allows adjustment of the slit gap, and reference numeral (6) indicates a choke bar for controlling the flow of the molten resin.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION FIG. 3 shows the production of a laminated film using the flat die of the present invention. The molten resin films from the two lips are attached to each other by the laminating roll (7) and the pressure bonding roll (8), and separated from the laminating roll by the peeling roll (9) to be taken up by a winding device (not shown). Go to

Whether a flat die that achieves a general purpose or a flat die that achieves a specific purpose, one or both of the two series is
It may have a structure of a laminated film of layers. As shown in FIG. 5, such a flat die has a stacking plate (5) on the upper part of the die head (1), and at least one series of resin flow paths and resin manifolds (one series in the illustrated example) have two types. It is a flat die configured such that a laminated film having three layers or four layers can be produced by making it possible to supply the synthetic resin of.

[0014]

By using the flat die of the present invention, all the problems of the above-mentioned multilayer die are eliminated in principle,
The operational difficulties are resolved. That is, the backflow of molten resin that may occur at the start and end of operation, and the waste of resin that occurs to prevent the backflow are eliminated, and a laminated film composed of two layers of two kinds of synthetic resins can be easily manufactured. You can

For a conventional simple structure T-die, 2
Although one or more must be used, each has a certain size, so there is naturally a restriction on arranging them in close proximity, and the distance until the two molten resin films merge is reduced. I can't. Therefore, the temperature of the resin falls below the range suitable for stacking before joining. If the extrusion temperature of the resin is increased in consideration of this, the deterioration of the resin will be caused.

If a stacking plate is provided on the upper portion, it is easier than the case where a multi-layer laminated film is used and a multi-manifold type die is used.
Also in this embodiment, the two kinds of molten resin integrated by the stacking plate must have similar physical properties, but there is no restriction that the physical properties of the molten resins passing through different resin flow paths and the manifold are close to each other. As compared with the case where a feed block type die is used, it is possible to give a variety to the combination of resins used as materials.

The flat die in which the opening positions of the two lips are arranged with a height difference with respect to the discharge direction of the molten resin, the side with the lower lips can be arranged closer to the vacuum forming roll, and thus two dies are arranged. The resin film can be extruded in close proximity, and can be brought into contact with the vacuum forming roll while keeping the distance from the lip short. This flat die is suitable for the improved method of manufacturing the plastic foam sheet described above. In this case, the difference in height between the two lips is determined mainly based on the radius of curvature of the vacuum forming roll.

[Brief description of drawings]

FIG. 1 is a conceptual cross-sectional view showing the structure of a multi-manifold type flat die in the conventional multi-layer die technology.

FIG. 2 is a conceptual cross-sectional view showing the structure of a feedblock type flat die in the conventional multi-layer die technology.

FIG. 3 is a conceptual cross-sectional view of an apparatus showing the structure of a flat die that achieves the general purpose of the present invention and using it to produce a laminated film.

FIG. 4 is a specific cross-sectional view showing the structure of a flat die that achieves a specific object of the present invention.

FIG. 5 is a conceptual cross-sectional view showing a modification of the flat die of the present invention.

[Explanation of symbols]

1 die head 2A, 2B resin flow path 3,3A, 3B manifold 4,4A, 4B Lip 41 lip cover 5 Stacking plate 6 chalk bars 7 laminated rolls 8 Crimping roll 9 Peeling roll

Claims (3)

[Claims] 1. A flat die for manufacturing a laminated film by melt-extruding a synthetic resin, comprising two series of resin flow paths and two series of resin manifolds provided in parallel in one die head. And a flat die with two lips that run in parallel and open separately. 2. The flat die according to claim 1, wherein the positions where the two lips are opened are arranged with a height difference in the discharge direction. 3. A stacking plate is provided on the upper part of the die head so that two kinds of synthetic resins can be supplied to at least one series of resin flow path and resin manifold.
The flat die according to claim 1 or 2, which is configured to be capable of producing a laminated film having three layers or four layers.