JPS6357224B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cooling device used in an inflation method for molding synthetic resin tubes.

In the conventional inflation method, the tube extruded from the die of an extruder is first cooled by air cooling, then secondarily cooled by air cooling or water cooling, and then pinch rollers pass through a stabilizer plate with a V-shaped cross section to cool the tube. The tube is stretched, folded in half, and rolled, but especially in the case of medium-pressure polyethylene, the temperature of the tube does not drop even after secondary cooling, and the surface that hits the stabilizer plate cools and solidifies, causing the stabilizer to Since the side that is not touched is stretched by the pinch roller, there is a drawback that a uniform tube cannot be obtained. This is a problem with the above cooling method. In the case of air cooling, it is necessary to blow a large amount of air around the tube, but the cooling effect is small. Furthermore, since the cooling speed is slow, the polymer tends to crystallize and become opaque. In addition, although the transparency of the one-set water-cooled type is good, since the cooling is done by absorbing heat from the water, it can only absorb heat by the amount of temperature rise of the cooling water. Therefore, a large amount of cooling water is required. Moreover, it is very difficult to continuously create a uniform layer of water that comes into contact with the tube surface, and if you try to create it at high speed, the water layer will not become flat. Furthermore, using large amounts of water is extremely dangerous.

This invention was made in view of these points, and relates to a cooling device not only for medium-pressure polyethylene but also for the inflation method when molding synthetic resin tubes. The object of the present invention is to provide a cooling device that has a high cooling effect, can uniformly cool the entire circumference of the tube, and can also apply a surface modifier or the like if necessary.

An embodiment of the present invention will be described below with reference to the drawings.

1 is a hollow annular cooler body with a substantially quadrilateral cross section; 2
3 is an annular liquid storage chamber divided by partition walls along the outer periphery of the cooler main body 1, and 3 is provided at appropriate intervals along the inner periphery of the liquid storage chamber 2 at the bottom of the storage chamber 2. The aerosol generator 3 is composed of a large number of aerosol generators, for example high-frequency generators. 4
Reference numeral 5 denotes the water that has entered the liquid storage chamber 2, and 5 is a ventilation chamber obtained by dividing the cooler main body 1 into two together with the liquid storage chamber 2. The ventilation chamber 5 has a key-shaped cross section and an annular shape. Reference numeral 6 denotes an annular air outlet provided at the lower part of one side of the air blowing chamber 5, and this annular air outlet 6 is located at the lower inner circumference of the cooler main body 1. Reference numeral 7 denotes a particle sorting tube whose upper end is fixed to the periphery of a hole bored in the top plate of the liquid storage chamber 2 at a position corresponding to each of the aerosol generators 3, and the lower end of this particle sorting tube 7 is close to the water surface of the water 4. However, the liquid storage chamber 2 and the ventilation chamber 5 communicate with each other through the particle sorting cylinder 7. 8 is a primary air blower pipe that blows air into the liquid storage chamber 2; 9 is a float switch that measures and detects the amount of water 4 in the liquid storage chamber 2; 1;
0 is a solution injection pipe that pours water 4 into the liquid storage chamber 2 upon detection of this float switch 9; 11 is a secondary air blowing pipe that sends secondary air into the ventilation chamber 5; is provided with an air volume control valve 11a. 12 is a drain storage tank provided at the bottom of the air outlet 6 and at the lower end of the inner circumference of the cooler main body 1;
is an outlet provided in this drain storage tank 11. Reference numeral 14 indicates a substantially cylindrical cover extending upward from the upper inner circumferential edge of the cooler main body 1, and reference numeral 15 indicates a plurality of suction devices provided at appropriate intervals around the upper edge of the cover.

Next, an example in which this cooling device is used for tube molding of medium pressure polyethylene will be explained with reference to FIG. The tube 18 extruded from the die 17 of the extruder 16 extends upward along the outer periphery of the guide rod 19, and is cooled by an air-cooled primary cooler 20.
Further, the tube 18 is stretched, passes through the cooling device according to the invention located above the frost line of the tube 18, is cooled by the cooling device, and is guided by the stabilizing plates 21, 21 having a V-shaped cross section. It is stretched by pinch rollers 22, 22, folded in half, and wound into a roll at a location not shown. In the above cooling device, the primary air blow pipe 8 is opened and a fixed amount of air is constantly blown into the liquid storage chamber 2. At the same time, the aerosol generator 3 is operated to generate an aerosol 23 consisting of a large number of water particles. This results in aerosol 2
3 enters the particle sorting tube 7 by the primary air, but large and heavy particles fall on the water surface 4, and only small and light particles rise inside the particle sorting tube 7 by the air and enter the ventilation chamber 5. . Because the secondary air pipe 11 is opened in advance and secondary air is sent into the ventilation chamber 5, the aerosol 23 that has entered the ventilation chamber 5 is sent to this secondary air and directed toward the annular outlet 6. blown away. Moreover, the interior of this ventilation chamber 5 is annular, and the aerosol 23 entering from a plurality of particle sorting cylinders 7 located at appropriate intervals along the circumference of this annular ventilation chamber 5 is diffused within the ventilation chamber 5. ,
The air is homogenized and blown out from an annular air outlet 6 provided along the inner circumference of the cooler body 1. As a result, the aerosol 23 uniformly hits the outer periphery of the tube 18. Since this tube 18 has heat, each aerosol 23 that hits this tube 18 immediately evaporates,
The tube 18 is cooled by the heat of vaporization during this evaporation. Since this aerosol 23 is extremely small (preferably 10μ or less), it evaporates immediately when it hits the tube 18, and a large number of aerosols 23
hits the outer circumference of tube 18 continuously, and tube 1
No. 8 is cooled around the entire circumference. The aerosol 23 that did not directly hit the tube 18 or evaporate floats inside the cylindrical cover 14, contacts the outer periphery of the tube 18 within the cover 14 and evaporates, or is sucked by the suction device 15. Exhaust to appropriate locations. Therefore, since a large number of aerosols 23 continuously come into contact with the tube 18 from the annular outlet 6 of the cooler main body 1 to the upper part of the cover 14, the aerosol 23 comes into uniform contact with the tube 18 passing through this area. cooled down.

FIG. 3 shows a cooling device of the present invention provided on the outer periphery of the tube 18 below the frost line, in place of the above embodiment. In this case, as in the above embodiment, the aerosol 23 is distributed around the entire circumference of the tube 18.
is sprayed evenly and makes contact. tube 18
Because it is still in a molten state, the aerosol that comes into contact with it 23
vaporizes instantly, and the heat of vaporization at that time takes away the heat from tube 18. Therefore, when the tube 18 passes through this cooling device, it is reliably cooled, and in this embodiment, it is possible to arrange the molecules in a manner close to a molten state.
Therefore, the molded tube 18 has improved transparency and strength compared to conventional tubes, and furthermore, the tube 18 has a biaxially balanced strength.

In this way, the cooling device of the present invention differs from the conventional water-cooled cooling system, which uses water to absorb heat. That is, when absorbing heat from water in a conventional water-cooled system, for example, even if 1 c.c. of water goes from 25°C to 35°C, only 5 cal of heat can be absorbed. If 1 c.c. of water at 25°C is evaporated, 25°C
When the temperature increases from 100℃ to 100℃, there is an endotherm of 75cal, and when water at 100℃ is evaporated, it becomes 540cal. therefore total
An endotherm of 615 cal takes place. Therefore, the latent heat of vaporization system of this invention absorbs more than 100 times more heat than the conventional water-cooled system. Therefore, the cooling efficiency is extremely high, and the amount of water is 1/100 compared to conventional water cooling systems.
~1/200 amount is fine.

Using the device of this invention, this was actually done with a width of 250 mm.
A medium-pressure polyethylene tube with a thickness of 50 μm was molded by the inflation method, but the amount of water used was 2/h, and the temperature decreased from 70°C to 42°C. When a tube that had been kept at a temperature of around 70°C as in the past was bent, the orientation of the internal molecules changed, resulting in a decrease in strength and the so-called selvedge phenomenon. However, in the case of the above example, since the temperature of the tube had dropped to 42°C, there was almost no difference in the strength of the bent portions at both ends of the tube due to the pressure during removal with the pinch roller compared to the flat plate portion, and the above-mentioned ear-sagging phenomenon was observed. It's gone. In addition, the opening property is good, and the degree of mixing of additives such as slip agents into the raw material during tube molding can be reduced. In addition, in the case of conventional air-cooled cooling, the temperature in the work room may exceed 40℃ in the summer, and in this case warm air must be blown into the tube, and in the winter
The temperature will be around 10℃. This temperature difference creates variations in the cooling effect. In this regard, in the case of this invention,
Because the cooling is performed using uniform fine water droplets, the cooling effect is stable without being affected by temperature changes within the work room. Furthermore, the temperature inside the device is kept constant due to the heat of vaporization when the water 4 in the solution storage chamber 2 is aerosolized.

Furthermore, in this invention, when water is aerosolized and sent to the ventilation chamber 5, only the light particle aerosol 23 is made to rise inside the particle sorting tube 7 by the primary air, and heavy and large particles are not allowed to rise inside the tube 7. figure,
As a result, particles are sorted, and only small particles are sent to the ventilation chamber 5. Therefore, the fine particles of the aerosol 23 sprayed onto the tube 18 have a uniform size. The size of the particles to be sorted can be arbitrarily selected by adjusting the pressure of the primary air or adjusting the length of the particle sorting cylinder 7. Moreover, by adjusting the volume of secondary air sent into the blowing chamber 5 using the control valve 11a of the secondary air blowing pipe 11, the concentration and speed of the aerosol 23 blown out from the annular outlet 6 of the blowing pipe 5 can be adjusted. Furthermore, the aerosol 23 sent by this secondary air
Since the air blowing chamber 5 is annular, the air is diffused and uniformized in an annular shape, and is then blown out from the annular outlet 6. Therefore, the aerosol 23 is uniformly attached to the outer periphery of the tube 18, and the size of each attached particle is also uniform, so that the tube 18 is cooled more reliably and uniformly. Moreover, as described above, the concentration and spraying speed of the aerosol 23 can be freely adjusted, and the cooling speed can be increased.

In addition, instead of the water 4 in the liquid storage chamber 2 of the cooling device in the above embodiment, a solution containing a surface modifier such as a surfactant and an antistatic agent is added to a solvent such as water, thereby simultaneously cooling the tube 18. tube 1
A surface modifier can be applied to the surface of 8.
In this case, since the aerosol 23 is sprayed onto the tube 18 as in the above embodiment, the tube 1
The water in the aerosol 23 that has come into contact with the tube 18 is vaporized by the heat of the tube 18, and the surface modifier is transferred to the tube 1.
8. Adheres to surfaces. Since a large number of aerosols adhere to each other continuously, an extremely thin film made of the surface modifier is formed on the surface of the tube 18. At this time, since a surfactant is added to the above solution, the surface tension is reduced, and when the aerosol 23 adheres to the tube 18, the aerosol 23 spreads on the surface of the tube 18, forming a continuous extremely thin film. .

At the same time, the tube 18 is cooled by the evaporation of water in the aerosol 23.

Such application of the surface modifier at the same time as cooling can be performed in any of the embodiments shown in FIGS. Since the surface modifier can be uniformly sprayed onto the tube 18, the extremely thin film made of the surface modifier formed on the tube 18 is also uniformly formed. Furthermore, the surface modifier is automatically applied at the same time as cooling during tube molding, which is extremely convenient.

Note that the surface modifier herein includes antistatic agents, antifogging agents, antifungal agents, antirust agents, and the like.

In addition, when the above water is aerosolized, cover 1
By opening the upper part of the cooler 4, it is not necessary to provide the suction device 15, and the amount of aerosol generated and the pressure of the air can be adjusted, thereby suppressing the discharge of aerosol to the outside of the cooler body 1 or 1'. Furthermore, in an embodiment in which a solution containing a surfactant and a surface modifier is aerosolized, the suction device 15 is not provided, and the upper end of the cover 14 is bent to be close to the outer surface of the tube 18, so that only water vapor leaks from the upper part of the cover 14. By providing a mesh or the like, the aerosol 23 inside the cover 14 becomes denser, ensuring that the aerosol 23 containing the surface modifier contacts and adheres to the tube 18, resulting in a more uniform ultra-thin film of the surface modifier. It will be done.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention, and FIG. 1 is an enlarged sectional view of a main part showing how the invention is used, and FIGS. 2 and 3 show how the invention is used. In the figure, 1 is a cooler main body, 2 is a liquid storage chamber, 3 is an aerosol generator, 5 is a blower chamber, 6 is an annular outlet, 7 is a particle sorting cylinder, and 8 is a primary air blower pipe.

Claims (1)

[Scope of Claims] 1. An annular cooling machine body into which a tube extruded from an extruder in the inflation method of synthetic resin molding is inserted is provided, an annular ventilation chamber is provided in the upper part of this cooling machine body, and this ventilation An annular air outlet of the ventilation chamber is provided on one side of the chamber, that is, on the inner periphery of the cooler body,
A liquid storage chamber is provided below the ventilation chamber, water is poured into the lower part of the liquid storage chamber, and an appropriate means is provided to turn this water into an aerosol, the lower end of which opens above the water surface, and the upper end of which opens into the ventilation chamber. A suitable number of particle sorting tubes are provided at intervals along the annular shape of the cooler body, and a primary air blowing pipe port is provided in the liquid storage chamber to send aerosol into each of the particle sorting tubes, and each of the particle sorting tubes is A secondary air blowing pipe opening is provided on the outer periphery of the blowing chamber to transfer the aerosol rising from the tube into the blowing chamber to the annular blowing outlet, and a secondary air blowing pipe opening is provided along the outer periphery of the tube that encloses the annular blowing outlet and is inserted through the main body of the cooler. 1. A cooling device comprising a cover having a constant length in the direction of movement of the tube. 2. An annular cooler body is provided through which the tube extruded from the extruder in the inflation method of synthetic resin molding is inserted, an annular ventilation chamber is provided in the upper part of the cooler body, and one side of this ventilation chamber, i.e. An annular outlet for the ventilation chamber is provided on the inner circumference of the cooler body,
A liquid storage chamber is provided below this ventilation chamber, a solution of a surface modifier added to a solvent such as water is placed in the lower part of this liquid storage chamber, and an appropriate means is provided to turn this solution into an aerosol. A suitable number of particle sorting cylinders are provided at intervals along the annular shape of the cooler body, and the lower end thereof is open, and the upper end thereof is open to the above-mentioned ventilation chamber, and the aerosol is sent to each of the above-mentioned particle sorting cylinders in the liquid storage chamber. A primary air blowing pipe opening is provided, and a secondary air blowing pipe opening is provided on the outer periphery of the blowing chamber for transferring the aerosol rising into the blowing chamber from each of the particle sorting tubes to the annular blowing outlet, and the annular blowing outlet is enclosed therein. ,
A cooling device characterized in that a cover having a constant length in the direction of movement of the tube is provided along the outer periphery of the tube inserted through the cooling device main body.