JPH0120111Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an apparatus for depositing powder on the inner surface of an blown film within an blown bubble.

Conventionally, in order to give blown packaging films anti-rust and sterilizing effects, a method has been adopted in which a powdered vaporized rust preventive agent or a powdered sterilizer is attached to the inner surface of the blown film. .

In addition, in the conventional blown film method, when the blown film extruded from an inflation die is wound up with a roll, the two overlapping films adhere to each other and are difficult to peel off. It may become. This is called blocking, and in order to prevent this, a method is adopted in which a powdered anti-blocking agent is applied thinly to the inner surface of the inflation film.

Devices for this purpose include the electrostatic powder dispersion device disclosed in Japanese Utility Model Publication No. 47-34033 and Japanese Patent Publication No. 51-1454, and the closed-circuit blower air powder non-spreading device disclosed in Japanese Patent Application Laid-open No. 49-101488. However, none of these takes into account the powder that does not adhere to the film and falls onto the mandrel of the inflation die.

Japanese Utility Model Publication No. 47-34033 describes a powder dispersion device equipped with a tray to catch fallen powder, and JP-A-49-101488 describes a powder dispersion device equipped with a powder collection hood. However, as is clear from the drawings, there is always a gap between the tray or collection hood and the film, and powder can easily fall through this gap. If the gap between the film and the film is eliminated, the workability and moldability will be extremely poor. In other words, when the film is blown up for the first time, the tray etc. become very stiff and the workability becomes poor. Furthermore, it is possible that the formed film may be damaged by this saucer or the like.

In addition, the advantage of inflation film is that the fold diameter of the film can be changed freely, but in order to eliminate the gap between the film tray or collection hood and the film, it is necessary to adjust the tray or collection hood according to the fold diameter of the film. I have to prepare several.

When powder falls onto a mandrel, if the powder's thermal decomposition temperature is lower than the temperature of the mandrel, thermal decomposition will occur if left as is. Furthermore, even if the thermal decomposition temperature of the powder is higher than the temperature of the mandrel, if it is left at high temperatures for a long time, it will gradually deteriorate or thermally decompose. The deterioration or thermal decomposition products may cause coloring of the film or have an adverse effect on performance.

In addition, when dispersing using electrostatic methods, wind dispersion, or natural falling, there is a possibility that the powder will be charged with static electricity, and if the powder is flammable, there is a considerable risk of ignition or explosion due to static electricity. .

Also, Publication No. 46-26302 and Special Publication No. 43-
Publication No. 2583 discloses that in a device for extruding a powder-filled film using a downward inflation die, a rotating body is provided below a screw penetrating the mandrel at a considerable distance from the lower surface of the mandrel and hanging down. A device is described that places the powder on the top surface of the blown film and attaches the powder to the inner surface of the blown film, but this device does not require consideration of thermal deterioration or thermal decomposition of the powder due to the heat of the mandrel. In addition, since the powder that comes out of the rotating body and does not adhere to the inner surface of the film is not caught below and falls downward inside the inflation film due to gravity, the degree of powder adhesion to the inner surface of the film is low. At the same time, the powder tends to float inside the film, causing the explosion described above. Therefore, such a device for extruding a downward blown film cannot be directly applied to the commonly used upward blown film forming method of the present invention.

The present invention was developed in view of the above-mentioned drawbacks of the conventional technology, and its purpose is to pass a powder transport pipe through the mandrel portion of an inflation die in an upward inflation film forming apparatus, and to The opening end is formed near the upper surface of the central part of the mandrel inside the inflation bubble, and a screw for transporting powder is installed inside this powder transport pipe, and the powder is transported above the central part of the mandrel. A blade-like rotating body for feeding the inflation film from the surface to the inner surface of the blown film, which is the peripheral edge of the mandrel, is provided close to the top surface of the mandrel so as to be rotatable about the axis of the screw, and this blade-like rotation The body forms a powder movement passage space with the upper surface of the mandrel, and has a disk whose outer periphery is located near the resin outlet formed on the upper surface of the peripheral edge of the mandrel, and a lower surface of this disk for the powder movement. By constructing a plurality of blades installed radially in the passage space, the powder is transferred to the resin discharge part side of the inflation die inside the inflation bubble by the screw installed in the powder transport pipe. The powder is transported to the upper surface of the mandrel, and the powder is quickly and reliably conveyed to the inner surface of the blown film by the vane-like rotating body, so that the powder comes into contact with and adheres to the inner surface of the film. By minimizing the time that the powder remains on the heated die mandrel surface, thermal decomposition of the powder is prevented, and the scattering and floating of the powder into the inflation bubble is prevented. This effectively suppresses the risk of fire and explosion caused by floating powder.

In addition, although Japanese Patent Publication No. 50-9012 describes that the powder is mechanically transported into an inflation bubble using a screw built into the powder transport pipe in order to disperse the powder, this publication does not As described in the detailed description of the invention, it is difficult to uniformly adhere the powder to the inner surface of the film just by transporting it. However, the present invention makes this possible and enables efficient and uniform adhesion.

Hereinafter, the present invention will be explained in more detail based on embodiments shown in the drawings.

In FIG. 1, reference numeral 1 indicates an inflation die, and reference numeral 15 indicates a mandrel for the die 1. A gap 16 is continuously formed in the circumferential direction between the die 1 and the mandrel 15 for feeding the molten synthetic resin, and the synthetic resin rises through this gap 16 and is formed on the upper surface 18 of the die 1. It is extruded upward from the outlet 17 in a cylindrical shape.

A powder transport pipe 2 is provided vertically through the center of the mandrel 15, and its upper end opens at a position slightly above the upper surface of the mandrel 15. A powder transport screw 3 is rotatably installed inside the powder transport pipe 2.

A blade-like rotating body 8 is connected to the upper end of the cylindrical screw shaft of the powder transport screw 3.
This vane-like rotating body 8 is the upper surface 1 of the mandrel 15.
8. Therefore, the blade-like rotating body 8 rotates as the powder transporting screw 3 is driven. The blade-like rotating body has several blades 8b arranged radially at appropriate intervals in the circumferential direction of the lower surface of a disk 8a located near the resin outlet 17 formed on the upper surface of the peripheral edge of the mandrel 15. The mounting blades 8b may be linear or curved, and may have any shape as long as they can transport the powder 7 toward the outer circumference. Disk 8
The space between a and the upper surface 18 of the mandrel 15 is used as a powder moving passage, and the lower end of the blade 8b is located slightly apart from the upper surface 18 of the mandrel 15.

Furthermore, a gas supply pipe 4 for expanding the blown film is provided penetrating inside the powder transporting screw 3, the upper part of which passes through the vane-like rotating body 8, and the upper end 4a of the gas supply pipe 4 for expanding the blown film. is opened at the top of the vane-like rotating body 8.

The molten synthetic resin extruded upward in a cylindrical shape from the outlet 17 formed on the upper surface 18 of the die 1 is expanded by the gas ejected from the open end 4a of the gas supply pipe 4, and the inflation film 5 is formed. is formed.

FIG. 2 shows an embodiment in which a vane-like rotating body 8 is attached to the upper end of a drive shaft 9 independent of the screw 3 in close proximity to the upper surface 18 of a mandrel 15. This drive shaft 9 passes through the inside of the screw 3 and is rotatably supported, and further, a gas supply pipe 4 for expanding the inflation film is provided through the inside of this drive shaft 9. .

With the above configuration, the powder 7 is transported to the upper surface 18 of the central part of the mandrel 15 of the die 1 inside the inflation bubble 6 by the screw 3 installed in the powder transport pipe 2. is moved toward the inner surface of the blown film 5 in the passage space between the disk 8a and the upper surface portion 18 of the mandrel 15 by the action of the vane-like rotating body 8, particularly the blades 8b, and the powder is 7 is brought into contact with the inner surface of the inflation film 5 to be attached to the inner surface of the inflation film 5. At this time, the powder 7 is always moved toward the inner surface of the inflation film while being insulated from the upper interior of the inflation bubble 6 by the disc 8a of the vane-like rotating body 8. In addition, since the outer periphery of the disk 8a is located near the resin outlet 17 on the upper surface of the peripheral edge of the mandrel 15, the powder can be discharged near the inner surface of the blown film 5. body 7
The powder particles 7 can be more reliably prevented from scattering and floating into the inflation bubble 6, and the powder 7 can be more reliably attached to the inner surface of the inflation film 5.

It goes without saying that the diameter of the rotor 8 should be such that the outer periphery of the blade-like rotor 8 does not come into contact with the inflation bubble 6.

The vane-like rotating body 8 quickly transports the powder 7, which has been transported to the upper surface of the mandrel 15 by the powder transport pipe 2, to the inner surface of the inflation film 5. The rotational speed of the vane-like rotating body 8 is set within a range where the rotational speed is too low and the powder 7 is not transported, and the rotational speed is too high and the powder 7 is scattered and suspended in the inflation bubble 6. It is necessary to set it. If the rotational speed of the screw 3 installed in the powder transport pipe 2 falls within this range, the screw 3 should be connected to the blade-like rotating body 8 as shown in FIG. 1 or as shown in FIG. 3 to be described later. can be done. If the number of rotations of the screw 3 does not fall within this range, the blade-like rotating body 8 is attached to the rotational drive shaft 9 independent of the screw 3, as shown in FIG. 2 or as shown in FIG. 4, which will be described later. Install it so that you can set the desired rotation speed.

3 and 4, the powder transport pipe 2 is located at the outer periphery of the upper end of the powder transport pipe 2, and a heat medium circulation part 14a for temperature adjustment is provided on the upper surface of the mandrel 15.
In addition, the powder transport pipe 2 is provided with a heat medium circulation part 14b for temperature adjustment on the outer periphery of the part of the powder transport pipe 2 that penetrates the mandrel 15, and the mandrel 15 is connected to the upper surface of the mandrel 15 and the powder of the mandrel 15. A heat insulating portion 1 is provided on the inner surface of the through hole of the transport pipe 2.
An example of a mandrel having 2a and 12b is shown.

A space 13 was formed between the heat insulating part 12 and the heat medium circulation part 14 for temperature adjustment. This space 13 also effectively acts as a heat insulator. Feather-like rotating body 8
was provided close to the upper surface of the heat medium circulation section 14a located on the upper surface of the mandrel 15. and,
The powder 7 is transported to the upper surface of the heat medium circulation section 14a by the screw 3 installed in the powder transport pipe 2, and further transferred to the inner circumferential surface of the inflation film 5 by the blade-like rotating body 8.

In this way, the heat insulating section 12 and the heat medium circulation section 14
If installed, it is more effective to prevent heat from being transmitted from the mandrel 15 to the powder 7, and to prevent deterioration and decomposition of the powder 7 due to heat. The temperature adjusting heat medium supplied to the heat medium circulation section 14 is used for cooling. The medium may be water or air. However, if the temperature is too low and the temperature of the mandrel 15 decreases, a temperature-controlled heating medium may be circulated. The heat medium is supplied from the heat medium inlet 14c provided at the lower part of the heat medium circulation section 14, circulated in the upper circulation sections 14b and 14a, and then passed through the heat medium outlet 14d.
discharge from.

Furthermore, if necessary, these heat insulating parts 12
The heat medium circulation section 14 may include only the heat insulating section 12a on the top surface of the mandrel 15 and the heat medium circulation section 14a located on the top surface of the heat insulating section 12a, or the powder transport pipe 2 of the mandrel 15.
The heat-insulating portion 12b may be provided only on the inner surface of the hole through which the mandrel 15 passes, and the heat medium circulating portion 14b may be provided on the outer periphery of the powder transport pipe 2 at the portion where the powder transport pipe 2 passes through the mandrel 15.

Although the case where the heat insulating section 12 and the heat medium circulation section 14 are provided together has been described above, it goes without saying that only one of them may be provided as necessary.

In addition, in FIG. 3, the blade-like rotating body 8 is
FIG. 4 shows an embodiment in which the vane-like rotating body 8 is attached to a rotary drive shaft 9 independent of the screw 3.

Further, a known drive device was used for the drive shaft 9 of the screw 3 and the blade-like rotating body 8 which was made independent of the screw 3.

In all of the examples shown in FIGS. 1 to 4, an inflation die (die diameter: 120 mm) equipped with a powder transport tube containing a powder transport screw was used.

The resin used was low-density polyethylene (UBE polyethylene F522), and the powder was dicyclohexial ammonium nitrite (DICHAN), a volatile rust inhibitor. It is stated in the literature that this compound decomposes at about 171°C in response to heat.
As a comparative example, the powder left on the upper surface of the mandrel of a die at a die temperature of 150° C. started to color in about 10 minutes. Furthermore, at higher die temperatures, the time required for the powder to begin coloring becomes shorter.

In the embodiments shown in Figures 1 to 4, the die temperature during inflation film forming was
Although the temperature was 150°C, the powder could be adhered to the inner surface of the film without coloring.

In the embodiments of FIGS. 3 and 4, the die temperature is
Even when inflation film molding was performed at 180°C, the powder did not become colored and could be adhered to the inner surface of the film.

Further, the dicyclohexylammonium nitrite used in the form of powder is flammable and combusts explosively when suspended. However, in the apparatus shown in FIGS. 1 to 4 of the example, there was almost no powder floating in the inflation bubble, and there was no risk of ignition or explosion.

As is clear from the above explanation, since the present invention has the structure as described in the claims of the utility model registration, the powder transported by the screw to the upper surface of the central part of the mandrel of the die is transferred to the vane-like rotating body. By this action, the powder can be quickly and reliably sent on the upper surface of the mandrel to the inner surface of the blown film, which is the peripheral edge of the mandrel, and can be brought into contact with and adhered to the inner surface of the film. Therefore, the time that the powder remains on the heated die mandrel surface can be extremely shortened, preventing powder deterioration or thermal decomposition, preventing film discoloration and equipment performance deterioration. can do. Further, the powder is transported from the center to the periphery of the mandrel with the disc insulating the powder from the interior above the inflation bubble in the space between the disc of the vane-like rotating body and the upper surface of the mandrel. Since it can be transferred to the inner surface of the blown film and discharged near the inner surface of the blown film, it is possible to more reliably suppress the generation of powder scattered and suspended within the blown bubble. In addition, the risk of ignition or explosion due to the flying powder can be extremely reduced, and the powder can be reliably attached to the inner surface of the inflation film.

In addition, deterioration or thermal decomposition of the powder can be further ensured by providing an appropriate heat insulating section or heat medium circulation section for temperature adjustment between the mandrel and the powder passage part to prevent the heat of the mandrel from being transmitted to the powder. This makes it possible to more effectively prevent coloring of the film.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view showing one embodiment of the present invention, and FIGS. 2 to 4 are longitudinal cross-sectional views showing other different embodiments of the present invention. 1... Inflation die, 2... Powder transport tube, 3... Powder transport screw, 4... Expansion gas supply pipe, 5... Inflation film, 6... Inflation bubble. Inside, 7...
Powder, 8... vane-shaped rotating body, 9... independent drive shaft,
12... Heat insulating part, 13... Space included in the heat insulating part, 14... Heat medium circulation part for temperature adjustment, 15... Mandrel.

Claims (1)

[Claims for Utility Model Registration] (1) A powder transport tube is passed through the mandrel portion of the inflation die, and its open end is formed near the upper surface of the center of the mandrel within the inflation bubble. A screw for transporting powder is installed inside the powder transport pipe, and a blade-shaped screw is provided for transporting the powder from the upper surface of the central part of the mandrel to the inner surface of the inflation film that is the peripheral part of the mandrel. a rotating body is provided close to the upper surface of the mandrel so as to be rotatable about the axis of the screw;
This vane-like rotating body forms a powder moving passage space between the upper surface of the mandrel, and a disk whose outer periphery is located near the resin outlet formed on the upper surface of the peripheral edge of the mandrel, and a lower surface of this disk. A device for attaching powder to the inner surface of a blown film, characterized in that the device comprises a plurality of blades installed radially in the powder moving passage space. (2) The above-mentioned powder transport pipe is a powder transport pipe having a heating medium circulation section for temperature adjustment located on the outer periphery of the upper end of the powder transport pipe and provided on the upper surface of the mandrel, and the above-mentioned mandrel is An apparatus for applying powder to the inner surface of a blown film as claimed in claim 1, characterized in that the mandrel has a heat insulating portion on its upper surface. (3) The powder transport pipe is a powder transport pipe that has a heat medium circulation part for temperature adjustment on the outer periphery of the mandrel penetrating part of the powder transport pipe, and the mandrel has a heat insulating part on the inner surface of the through hole of the powder transport pipe. An apparatus for applying powder to the inner surface of an blown film according to claim 1, characterized in that the mandrel has a mandrel having: (4) The above-mentioned powder transport pipe is located on the outer periphery of the upper end of the powder transport pipe, and is connected to the heat medium circulation part for temperature adjustment provided on the upper surface of the mandrel, and also to the outer periphery of the mandrel penetrating part of the powder transport pipe. A utility model registration claim characterized in that the mandrel is a powder transport pipe having a heating medium circulation part for temperature adjustment, and the mandrel is a mandrel having a heat insulating part on the upper surface of the mandrel and on the inner surface of the through hole of the powder transport pipe. A device for adhering powder to the inner surface of an blown film according to item 1.