JPH08244098A - Film forming apparatus - Google Patents

Abstract

PURPOSE: To suppress generation or a flare within a specified range by providing a windbreak fence in the neighborhood of a cooling roll below the cooling roll. CONSTITUTION: A windbreak fence 5 has a flat sheet-like crosssection in the long direction of the width direction of a cooling roll 2 and is arranged approximately horizontally and the width is provided a little larger than the width of the cooling roll 2. Therefore, it is arranged in such a way that the central part is closest to the lowermost face of the cooling roll 2. By providing this windbreak fence 5, the cooling air blown from an air chamber 4 is stopped to advance as air resistance becomes larger at the narrow gap just below the cooling roll 2 and it is blown as a result to the opposite side from the gap of the windbreak fence 5. As the result, generation of a flare is suppressed within about 70mm and the film can be cooled uniformly over the width direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film forming apparatus for uniformly cooling and extruding a film extruded from a mold.

[0002]

2. Description of the Related Art In a conventional film forming apparatus, as shown in FIG. 3, a film f extruded downward from a mold 10 is wound around a cooling roll 20 for continuous cooling, and the cooling roll 20 is also used. Cooling air is blown out from the air chamber 30 provided on the lower side surface of the cooling roll 2
The surface of the film f wound around 0 is drawn by a drawing machine while being effectively cooled.

[0003]

However, in the conventional film forming apparatus described above, the air blown from the air chamber 30 is separated from the end of the film f, and the film f is separated from the winding of the cooling roll 20. In addition, since the behavior of the film f is such that it wraps around as shown by the arrow in the drawing to enter the inside and flows along the back side, and the central part of the film f is pressed, the central part of the film f is It bends like f ₁ and tries to curl inward, and so-called flare is generated. Due to the occurrence of flare, the obtained film lacks flatness and leaves a quality problem.

The present invention has been made in view of the above problems, and an object thereof is to solve these problems and suppress the occurrence of flare within 70 mm. The present invention provides a simple film forming apparatus.

[0005]

In the film forming apparatus of the present invention, a film extruded from a mold is wound around the lower half of a cooling roll, and air is supplied from an air chamber provided close to the cooling roll. In a film forming apparatus configured to be blown out and cooled while being uniformly pressed against a cooling roll and continuously drawn by a take-up machine, a windbreak fence is provided below the cooling roll and close to the cooling roll. Characterize.

[0006]

In the film forming apparatus of the present invention, since the windbreak fence is provided below the cooling roll and close to the cooling roll, it is possible to suppress the occurrence of flare within 70 mm.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The film forming apparatus of the present invention will be described below with reference to the drawings. FIG. 1 is a side view showing an example of the film forming apparatus of the present invention. In FIG. 1, reference numeral 1 denotes a film forming apparatus. In the film forming apparatus 1, an extrusion die 1 is provided above and a cooling roll 2 is provided below the extrusion die 1.

The film F continuously extruded from the extrusion die 1 travels downward and is wound around the lower half portion of the cooling roll 2, travels obliquely upward from the opposite side as shown in the drawing, and is guided by the guide roll. It is designed to be taken by a take-up machine (not shown) after passing through 3.

Reference numeral 4 denotes an air chamber. In this air chamber 4, a cooling air blow-out port 4a is formed on the side surface of the film F on which the film F has descended, along the surface of the cooling roll 2 around which the film F is wound. And is provided downward.

Reference numeral 5 is a cooling roll 2 just below the cooling roll 2.
It is a windbreak fence provided near the lower surface of the. This windbreak fence 5 has a flat plate-like cross-sectional shape in the longitudinal direction in the width direction of the cooling roll, and is installed substantially horizontally.
The width is set to be slightly larger than the width of the cooling roll 2. Therefore, the central portion is provided so as to be closest to the lowermost surface of the cooling roll 2.

Since the windbreak fence 5 is provided, the cooling air blown out from the air chamber 4 is
Since the air resistance is large in a small gap directly below the cooling roll 2, the forward movement is blocked, and as shown by the arrow in the figure, the air is blown out to the opposite side of the gap between the lower air chamber 4 and the windbreak fence 5. .

Therefore, unlike the conventional film forming apparatus, the cooling air does not come around from the side surface to press the film F from the upper surface to generate flare, and the film is uniformly cooled in the width direction, and A flat film without flare can be continuously taken up by a take-up machine.

[Embodiment 1] In the present embodiment, a flat plate-like windbreak fence having a width 6 cm wider than the cooling roll and a depth dimension of 10 cm is provided with a gap between the cooling roll and a portion directly below the cooling roll.
The film was formed by the T-die method using the film forming apparatus set to mm. A low-density polyethylene resin (LK-30 manufactured by Mitsubishi Petrochemical Co., Ltd.) was used as the resin material, and a film having a thickness of 60 μm was extrusion-molded. As a result of measuring this result with a flare measuring device as shown in FIG. 2, the flare value was 48 mm.

Example 2 A film having a thickness of 55 μm was extrusion-molded using the same film forming apparatus as in Example 1 and the same raw material resin. As a result, the flare value is 52.
mm. Example 3 A film having a thickness of 50 μm was extruded using the same film forming apparatus as in Example 1 and the same raw material resin. As a result, the flare value was 56 mm.

Comparative Example 1 A film having a thickness of 60 μm was extruded in the same manner as in Example 1 by using a film forming apparatus from which the windbreak fence of the above example was removed. As a result, the flare value was 86 mm.

The flare value is measured by using a flare measuring device as shown in FIG.
The film in which the iron bar 7 having the load of 10 is hung so that a uniform load is applied in the width direction is placed on the pedestal 6, and the reference line on the pedestal 6 and the projection line of the light projected from above are set. The maximum value D of the vertical distance was taken as the flare value.

As a result of the above test, it was possible to form a good film having a flare value of 70 mm or less in any of the examples.

The structure of the windbreak fence used in the film forming apparatus of the present invention may be any structure as long as it can prevent the cooling air from advancing from directly under the cooling roll to the front, and is not particularly limited to the examples. Instead, for example, an upright plate having a partition shape may be installed directly below the cooling roll, or even an edging shape having a gentle cross-section with a curved upper surface can be effectively used.

[0019]

In the film forming apparatus of the present invention,
Since the windbreak fence is provided below the cooling roll and close to the cooling roll, it is possible to suppress the occurrence of flare within 70 mm. Therefore, it is preferably used as a film forming apparatus.

[Brief description of drawings]

FIG. 1 is a side view showing an example of a film forming apparatus of the present invention.

FIG. 2 is a perspective view of a flare measuring device.

FIG. 3 is a side view showing an example of a conventional film forming apparatus.

[Explanation of symbols]

 1 Extrusion die 2 Cooling roll 3 Guide roll 4 Air chamber 5 Windbreak fence 6 Stand 7 Iron bar F film

Claims (1)

[Claims] 1. A film extruded from a mold is wound around a lower half of a cooling roll, and air is blown from an air chamber provided in the vicinity of the cooling roll to uniformly press the film against the cooling roll to cool the film. In the film forming apparatus, which is adapted to be continuously taken up by a take-up machine, a windbreak fence is provided below the cooling roll in the vicinity of the cooling roll.