JPS6144624A - Air cooling apparatus for forming tubular film - Google Patents

Abstract

PURPOSE:To make it possible to increase a film forming speed without lowering quality, by providing a plurality of air cooling chambers to a tubular film forming apparatus and providing an exhaust chamber to a primary air cooling chamber while providing an air supply chamber to a secondary air cooling chamber and making the wind directions and wind amounts of respective chambers adjustable. CONSTITUTION:An air ring 2 and an air cooling cylindrical chamber 4 are provided at the position surrounding the passage of the tubular resin 3 extruded from the ring shaped slit of a die 1. This chamber 4 is divided into the primary air supplying first chamber 4a positioned at the upper part of the air ring 2 and a secondary air supplying second chamber 4b positioned above said chamber 4a and formed as a gathering of plural chambers. These chambers are partitioned by an iris 5 being a boundary. An exhaust chamber 6 communicated with an exhaust port 7 is provided to the upper part of the first chamber 4a and air supply chamber 8 is provided to the lower part of the second chamber 4b.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical field to which the invention pertains] The present invention relates to an air cooling device for tubular film forming (extruding resin from a die into a cylindrical shape to form a tubular resin product).

[Prior art and its problems]

Conventionally, in order to mold a film tube from thermoplastic resin by the inflation method, the raw resin is heated and melted and extruded through an annular slit of a die to form a bubble, while air is blown from an air cooling ring to cool and crystallize. It passes through a folding device and is folded and taken out. The transparency of the film tube obtained by such an inflation method depends on the degree of cooling of the bubble.

However, if you increase the air volume of the air ring and rapidly cool the pull, you can obtain a film with good transparency, but for polyethylene, etc., which has a low melt tension, increasing the air volume increases the vibration of the bubbles, which tends to cause wrinkles. A high quality product is f! There was a ht point that could not be uploaded.

Therefore, there are attempts to provide air rings in two stages, upper and lower, to intensively cool the area near the solidification line as much as possible (for example, Japanese Patent Application Laid-Open No. 53-146764-F3). However, it is not possible to respond quickly to changes in the film size or expansion ratio, and the cooling air volume and temperature cannot be adjusted as desired, and the cooling efficiency is poor.

To solve this problem, we added a cylindrical chamber to the bottom annular air ring, and used an iris (a ring-shaped guide plate whose inner diameter can be increased or decreased) on its inner diameter plate to effectively cool the air with a small amount of air, while changing the inner diameter. By doing so, it is possible to cope with changes in film tube size and expansion ratio without changing the air ring, for example, in JP-A-59-39.
No. 524 exists.

This has the advantage that the chamber is also expandable and retractable in the height direction, and the upper end of the chamber can be approximately aligned with the solidification line position of the bubble, but the chamber surrounding the film tube is one chamber, i.e., a single chamber. Since it is formed only by a space, the cooling air blown from the bottom air ring is heated and heated by the high temperature molten resin extruded from the die, and the space between the cylinder and the molten resin of the film tube forming the chamber is heated. Convection occurs,
Cooling was insufficient, greatly affecting high-speed moldability and physical properties of the product. This causes problems in that the transparency and gloss of the film are poor during high-speed molding, and the impact strength of the film is reduced.

[Purpose of the invention]

The purpose of the present invention is to eliminate the disadvantages of the conventional example, and to divide the cooling air into primary air and secondary air in a detailed manner and to allocate the necessary parts when efficiently cooling with a small amount of air by using a chamber. Furthermore, the wind direction and volume of each air, as well as the cooling temperature, can be freely controlled, so the take-up speed can be increased while maintaining the physical properties of the film, and the blow-up ratio can be freely adjusted without reducing the physical properties of the film. The purpose of the present invention is to provide an air cooling device using tubular film that can be changed to

[Key points of the invention]

However, according to the present invention, in the case where a chamber for air cooling is provided to surround the tube-shaped resin discharged from the die, a plurality of chambers are formed so as to supply primary and secondary cooling air, and This is accomplished by providing an exhaust chamber in the primary air supply chamber and an air supply chamber in the secondary and lower air supply chambers so that the direction and volume of the air can be variably controlled.

[Specific examples of the invention]

Hereinafter, specific examples of the present invention will be described in detail with reference to the drawings.

Fig. 1 is a schematic diagram showing the air cooling device for tubular membrane production of the present invention! FIG. 2 is a plan view of the iris section, in which 1 is an annular die for discharging the resin melted and kneaded by an extruder (not shown), and 2 is an annular die installed on the die 1 to blow cooling air. Shows the air ring that comes out.

Furthermore, 3 in the figure is a tube that is melted and extruded from the die 1 into a tubular shape, and internal pressure is applied by air pumped from an air outlet (not shown). A shaped chamber 4 is provided.

In the device of the present invention, this chamber 4 includes a first chamber 4a for supplying primary air located above the air ring 2;
The book is divided into a first room 4a and a second room 4b for supplying secondary air located above the first room 4a, and is formed as a set of a plurality of books.

Both the first chamber 4a and the second chamber 4b are configured with a double wall whose side walls are slidable, so that they can be expanded and contracted in the height direction, and are continuous with each other with the iris 5 as a boundary.

Furthermore, the first chamber 4a has an exhaust chamber 6 in its upper part that communicates with the exhaust lower, and the second chamber 4b has an air supply chamber 8 in its lower part that communicates with the air supply port 9; The size of the air supply chamber 8 can be changed by the iris 5 and the iris 10 arranged in parallel below the iris 5, and by the iris 11 arranged in parallel above the iris 5. Further, the iris 12 is also used on the upper end plate of the second chamber 4b.

These irises 5, 10, 11, and 12 all have the same structure. Taking the iris 5 as an example, as shown in FIG. This is a ring-shaped guide plate that utilizes an aperture mechanism formed by stacking a large number of shaped blades 5b in the circumferential direction.

In addition to using such an iris mechanism as another embodiment, it is also conceivable to adopt another diaphragm mechanism capable of changing the inner diameter, such as a sliding plate protrusion method.

In the illustrated example, the chamber 4 is divided into only two chambers, the first chamber 4a and the second chamber 4b, but a third and subsequent chambers may be provided, such as tertiary air and quaternary air. In this case, all the secondary and lower air supply chambers have an air supply chamber like the second chamber 4b.

Next, the usage and operation of the device will be explained.

The cold air blown from the air ring 2 flows as primary cooling air in the first chamber 4a so as to form a bubble shape of the tubular resin extruded from the die l, and is discharged from the exhaust lower of the exhaust chamber 6. However, the amount of exhaust air and the direction of the airflow are adjusted by changing the opening diameter of the iris 5.10 and adjusting the size of the exhaust chamber 6 using the temperature of the exhaust air as a guide.

In addition, the air forced into the second chamber 4b from the air supply port 9 through the air supply chamber 8 or by natural suction is used as secondary cooling air in an amount that does not make the resin shape of the duplex 3 unstable. Frost line 13 of tube 3 as maximum amount
Rapidly cool the vicinity.

This secondary air is discharged from between the tube 3 and the iris 12, and the wind direction and air volume within the second chamber 4b can be adjusted by appropriately adjusting the opening diameter of the iris 5.11 and the opening diameter of the iris 12. can.

It is preferable that the difference between the diameter of the film tube 3 and the aperture diameter of the iris 10 be adjusted to 100 m* to 150 m, and the difference between the diameter of the tube 3 and the aperture diameter of the iris 5 to be adjusted to 10+m to 100 m.

The main objects to be cooled in the apparatus of the present invention are the following commonly used thermoplastic resins: low-density polyethylene, medium-density polyethylene, high-density polyethylene,
Polypropylene, poly-1-butene, ethylene, 1ffi
it: polyolefins such as acid-vinyl copolymers, polystyrene, polyvinyl chloride, polyvinylidene chloride, polyamide, polyester, etc.

In addition to tube forming using the above-mentioned inflation method, the apparatus of the present invention can also be applied to other forming methods such as the deflation method, the bottom blowing method, the top blowing method, and the internal water cooling method. It is applicable as long as it does not change.

〔Example〕

Wire low density polyethylene (density = 0.924g/ant, old = Ig/1) using a 500 Yongzhong circular die.
The total length of the cylinder forming chamber 4 is 3.
50 mm, cylinder internal f'fi is 1000 m+a, opening t'li of iris 12 is 900 tm, iris 11,5
．． The opening diameters of 10 are 850 m+a and 680 m, respectively.
The heights of the iris 11, 5.10 are 200 mm, 150 mm, and 100 mm, respectively, the bubble diameter is 1100 mm, the blow-up ratio is 2.2, and the take-up speed is 1.
A blown film with a thickness of 30 μm was molded at a speed of 00 m/min. The resulting film has a haze of 4.5
% and good brightness was obtained.

When a blown film with a thickness of 30 μm was similarly molded in the case where Iris 11, 5, and 10 were not used for the ratio 1 bite, the heath was 9% at a take-up speed of 20 m/min.

[Results of invention]

As described above, the air cooling device for the tubular MIIA of the present invention separates the cooling air into primary and secondary air when providing an air cooling chamber surrounding the naube-shaped fat discharged from the die. The amount that is insufficient in the primary cooling air is filled with secondary cooling air and below.
In addition, by exhausting the primary air that has been overheated by the molten resin, the frost line can be efficiently and rapidly cooled, and by adjusting the iris diameter and the blower air volume, each primary air can be adjusted in direction and volume. As a result, the cooling temperature can be freely controlled. As a result, the take-up speed can be increased while maintaining one physical property of the film, and the blow amplifier ratio can be freely changed without deteriorating the physical properties of the film.

[Brief explanation of drawings]

FIG. 1 is a schematic vertical side view showing an embodiment of the air cooling device for tubular film production of the present invention, and FIG. 2 is a front view of the iris portion. ■...Dice 2...Air ring 3...
・Film tube 4...Channo\45...1st
Room 4b...2nd room 5, 10.11.12.
...Iris 5a... Rotating plate 5b... Vane 6... Exhaust chamber 7... Exhaust port 8... Air supply chamber 9... Air supply port 13... Frost line

Claims (2)

[Claims] (1) In the case where an air cooling chamber is provided to surround the tube-shaped resin discharged from the die, a plurality of such chambers are formed to supply primary and secondary cooling air, and the chamber is provided for supplying primary air. The chamber has an exhaust chamber,
An air cooling device made of tubular film, characterized in that each of the secondary and lower air supply chambers is provided with an air supply chamber that can be variably controlled to control the wind direction and air volume. (2) The tubular membrane air cooling device according to claim 1, wherein the exhaust chamber and the air supply chamber are formed by an iris.