JPH0351567B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a cooling method and apparatus suitable for cylindrical thermoplastic resin products, particularly relatively thin ones, extruded from an annular slit of an extruder die. It is something.

(Prior Art and its Problems) As this type of cooling method, the following methods are conventionally known.

(a) Immediately after the cylindrical object of thermoplastic resin leaves the die and passes through a sizing ring, there is a method in which the cylindrical object is cooled in a water bath or by a shower. This method is suitable for cooling thick-walled pipes made by extruding hard vinyl chloride resin, but in the case of thin-walled thin film-like pipes made of soft resin, the shape is affected by the water pressure in the water tank. It is difficult to hold and wrinkles occur when winding up, making it unsuitable.

(b) A method of extruding a thermoplastic resin cylinder downward from a die and cooling it with water sprayed from a cooling ring surrounding it was disclosed in Japanese Patent Publication No. 55-47056.
has been disclosed. However, this method cannot be used for film-like thin cylindrical objects because it has disadvantages such as poor appearance due to water marks caused by sprayed water and unevenness in size due to shaking motion due to water pressure.

(c) Furthermore, there is a known cooling method in which a cylindrical thermoplastic resin is extruded downward from a die and drawn out of the tank by being wrapped around a roller provided in the tank or via a driven pinch roller. However, according to this method, if the distance from the die to the water surface of the water tank is long, the thermoplastic resin cylindrical object will oscillate until it is cooled, causing unevenness in the size of the cylindrical object. This tendency is particularly remarkable in the case of thin cylindrical objects. It is also conceivable to compensate for the drawbacks of the above method and to add a release agent for preventing internal adhesion as a pile agent to the lower part of the cylindrical object in order to keep the shape of the cylindrical object stable. However, even if a pile agent is injected into the cylindrical object using this method and the level of cooling water in the water tank is brought close to the die, the temperature of the extruded thermoplastic resin cylindrical object is around 200°C. Furthermore, even if the temperature of the cooling water in the water tank is low, the temperature of the pile agent will gradually rise, making it impossible to sufficiently cool the cylindrical object.
When the film was formed through the subsequent stretching process, its physical properties sometimes deteriorated.

Further, in the case where the cylindrical object is multi-layered, it contains many resins and the quenching must be done in a way that is compatible with the most sensitive resin, so special consideration must be given to the quenching.

(Means and effects for solving the problems) This invention was developed in view of the above-mentioned technical background, and it is possible to effectively and efficiently produce thermoplastic resin cylindrical objects without impairing the physical properties of the final product film. The purpose is to provide a method and apparatus for stable rapid cooling.

Regarding the cooling method, the present invention includes the following steps: While pulling out a cylindrical thermoplastic resin extruded from an annular slit of an extruder die with a pinch roller in a water tank disposed below the die,
In the method of cooling the cylindrical object between a die and a pinch roller, gas at a predetermined pressure is supplied into the cylindrical object through the core of the die, and the upper outer peripheral surface of the cylindrical object is brought into contact with cooling water. Immediately after, the inner circumferential surface of the guide tube, which is a short tube of a predetermined size, is brought into contact and guided, and after that, the gap formed between the cylindrical object and the long tube is formed below the position directly below the contact guide portion.
A predetermined flow rate of cooling water is introduced into the cylinder, forming a film on the outer peripheral surface of the cylindrical object, and causing the cooling water to flow down to the water tank. In a water tank equipped with a pinch roller that pulls out a thermoplastic resin cylindrical object extruded from an annular slit at a position below the die, the cylindrical object is surrounded at a position above the die and the pinch roller, and the cylindrical object is A weir with an overflow pipe is provided on the outer circumferential surface of the cylindrical body to allow the cooling water to flow down to the water tank in the form of a film of uniform thickness. The weir has an inner circumferential wall that is parallel to the cylindrical object and spaced therefrom, and an outer circumferential wall that has an upper edge on the outer periphery of the inner circumferential wall at a position higher than the upper edge of the inner circumferential wall. , a water supply pipe that supplies cooling water is connected to the space formed by the inner circumferential wall and the bottom wall that seals between the lower edge of the outer circumferential wall, and the inner circumferential wall of the weir contacts the cylindrical object at an upper position. It is formed by connecting a short tube to be guided and a long tube that maintains a gap with the cylindrical object below the short tube and has an opening at the top that communicates between the gap and the space inside the weir. configured.

According to the present invention as described above, the cylindrical object is stably maintained at a predetermined dimension on the guide surface, and the cooling water is maintained at a predetermined flow rate with an almost constant flow rate, so that the shape is always stable, that is, the shape is unstable. This means that a very wide area can be effectively cooled without being subject to any impact forces or fluctuations.

(Example) The cooling method and apparatus thereof based on the present invention will be described below with reference to Examples shown in the drawings.

FIG. 1 is a sectional view of an apparatus used in a first embodiment of the invention.

A weir 1 is disposed below the die 3, and a pinch roller 5 is disposed further below.

An annular slit (not shown) is provided at the bottom of the die 3, and a cylindrical object 4 of thermoplastic resin is extruded downward from the annular slit. Although not shown, the die 3 is provided with a core for guiding a gas supply pipe that feeds gas at a substantially constant predetermined pressure and volume into the cylindrical object 4. Therefore, the cylindrical object 4 has a stable cylindrical shape with a substantially constant volume.

The weir 1 is a double cylindrical tank with an open top, and an outer circumferential wall 12 is provided at a distance from an inner circumferential wall 11 in order to maintain a predetermined amount of water.
The upper edge is positioned higher than the upper edge of the inner peripheral wall 11. The bottom wall 13 has a
A water supply pipe 6 for supplying cooling water is connected to the space formed by the inner circumferential wall 11 and the outer circumferential wall 12, and furthermore, a water supply pipe 6 is connected to the upper end of the inner circumferential wall 11 so that the cooling water is maintained at a substantially constant level above the upper edge of the inner circumferential wall 11. An overflow pipe 7 with a positioned opening is connected.

The inner circumferential wall 11 of the weir is formed by an upper short cylinder 9S and a lower long cylinder 9L.

The short tube 9S guides the cylindrical object 4 in contact with the upper part thereof in order to keep the cylindrical object 4 in a stable state. The short cylinder 9S is a high temperature cylindrical object 4.
It is set at a position slightly lower than the water level of the cooling water in the weir 1 so that the short pipe 9S contacts the short pipe 9S after it has been cooled to some extent. This is because if the cylindrical object 4 is not cooled even a little before being guided, the cylindrical object 4 will be stuck to the short tube 9S and lose its shape. Note that it is desirable that the inner surface of the upper end of the short cylinder be chamfered to reduce resistance in guiding the cylindrical object.

The long cylinder 9L is for flowing cooling water in a film form between it and the cylindrical object 4, and has an inner diameter larger than the inner diameter of the short cylinder 9S so as to form a gap between the long cylinder 9L and the cylindrical object 4. It is somewhat large. The interval 〓 is determined by taking into consideration the holding stability of the cylindrical object and the amount of cooling water.

The short tube 9S and the long tube 9L may be connected as appropriate, but at least an opening must be provided in the upper part of the long tube so that the gap communicates with the inside of the weir. In terms of a preferred form, the two cylinders are preferably connected by a groove-shaped ring 10 that opens radially inward as shown in the figure. A large number of holes 15 are formed on the back surface of the groove-shaped ring 10 to facilitate the introduction of cooling water into the upper part of the long tube 9L, and a large number of holes 16 are formed on the upper surface of the groove-shaped ring 10. It is more desirable to allow the cooling water above to heat up and circulate without stagnation.

Furthermore, in order to allow more cooling water to flow down without making the distance between the long tube 9L and the cylindrical object 4 excessively large, it is preferable to cut a downward groove in the inner surface of the long tube 9L. If the groove is formed into a spiral shape, the residence time of the cooling water will be longer, and the cooling efficiency will be further improved.

Note that if the short tube 9S and/or the long tube 9L described above are each divided into two parts and connected to each other so as to be openable and closable with a hinge or the like, it becomes easier to pass a cylindrical object through the tube at the beginning of operation of the apparatus.

In the above embodiment, the preferred dimensions of each part are as follows:
The distance between the cylindrical object and the inner peripheral wall (long cylinder) is 1 to 15 mm,
It was confirmed through experiments that the length of the short tube was 1 to 30 mm, and the interval between the short tube and the long tube was 1 to 20 mm.

Note that air is usually sufficient as the gas to be pressurized into the thermoplastic resin cylinder, but inert gas is more preferable. Further, the outer diameter of the cylindrical object is detected by a diameter detector 17, and the signal is negatively fed back to the control valve for the gas to be pressurized to keep the shape (diameter) of the cylindrical object constant at a set value. Preferably controlled.

A pair of pinch rollers 5 are arranged below the weir 1 mentioned above. The pinch rollers 5 are used to feed the cooled cylindrical object 4 into a bag band shape. Then, after the inflation process, both edges of the bag strip-like material are cut off and then peeled off to obtain two films. A pile agent 8 as a release agent is originally supplied from above. And the pile agent 8 is the cylindrical object 4
The pinch roller 5 is placed in the water tank 2 under such conditions that its shape will not be distorted by the pressure of gas such as air applied from inside the tank.
The water level in the water tank 2 is set to a predetermined level by setting the opening position of the upper end of the overflow pipe 2F attached to the water tank 2. This is to cope with the problem that cooling water from above flows down into the water tank 2 and the water level becomes unstable. The liquid level in the pile 8 is detected by a sensor (not shown), and the liquid is always supplied from a supply pipe (not shown) arranged in the die 3 so as to be at the same level as the water level in the water tank 2.

According to the device of this embodiment, the cylindrical object 4, which is pulled out downward while inflated by the internal air pressure, is
After entering the water surface in the weir 1 and being initially cooled, it is sufficiently cooled by the cooling water flowing down in a film form between the long tube 9L and the long tube 9L while being guided by the short tube 9S. After the cooling water flows into the groove ring 10 through the holes 15 and 16, it flows into the gap from the annular opening between the short tube 9S and the long tube 9L.

At this time, even if the amount of water supplied from the water supply pipe 6 and the amount of water flowing down along the cylindrical object 4 are not equal, the excess water will overflow from the overflow pipe 7, so the level in the weir 1 will always be maintained. The cooling water becomes constant, and the flowing cooling water also forms a stable film shape. Therefore, in cooling the cylindrical object 4, rapid cooling is possible because the cooling area is extremely sufficient, and the cooling water flows down along the outer surface of the cylindrical object all the way to the water tank for a long period of time, making it possible to cool the cylindrical object 4. No water pressure or impact pressure is applied to the object 4, the film remains constant, and the cooled cylindrical object remains stable without damaging its appearance.

In this way, the cylindrical object 4 is rapidly cooled by the cooling water flowing down, and is then shaped into a bag band by the pinch rollers 5 and sent to the next process. Since the pile liquid level and the water level in the water tank 2 are maintained at approximately the same level, when the cylindrical object 4 is sandwiched between the pinch rolls 5, its shape is extremely stable and wrinkles do not occur.

(Effects of the Invention) As described above, the present invention allows a large amount of cooling water to be formed on the outer circumferential surface of the cylindrical object while guiding the cylindrical object for a long time and without applying any water pressure or impact pressure. Not only is cooling effective, but even if the cylindrical object is a thin film, its shape and shape will be maintained during cooling.
Dimensions and appearance will not be damaged. Particularly when the cylindrical object is made up of multiple layers, effective quenching can be performed, so that a film with good physical properties can be obtained after stretching, and the effect is remarkable.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an apparatus according to an embodiment of the present invention. 1...Weir, 2...Aquarium, 3...Dice, 4...
Thermoplastic resin cylindrical object, 5...Pinch roller, 6
... Water supply pipe, 7 ... Overflow pipe, 8 ... Pile agent, 9
S...Short tube, 9L...Long tube, 10...Groove ring, 1
1...Inner peripheral wall, 12...Outer peripheral wall, 13...Bottom wall,
15, 16...hole.

Claims (1)

[Scope of Claims] 1. A cylindrical object of thermoplastic resin extruded from an annular slit of a die of an extruder is pulled out by a pinch roller in a water tank disposed below the die, and the cylindrical object is moved through the die. In this method, gas at a predetermined pressure is supplied to the inside of the cylindrical object through the core of the die, and immediately after contact with the cooling water, the upper outer peripheral surface of the cylindrical object is cooled with a short cut of a predetermined size. Contact guidance is made on the inner peripheral surface of the guide tube consisting of a cylinder, and then a gap is formed between the cylindrical object and the long tube below the position directly below the contact guide portion.
A method for cooling a thermoplastic resin cylindrical object, comprising: flowing a predetermined flow rate of cooling water into the cylindrical object, forming a film on the outer peripheral surface of the cylindrical object, and causing the cooling water to flow down to the water tank. 2. Supply the pile agent at a predetermined level into the cylindrical object at the entry point to the pinch roller, and place the pile agent retention area in the cylindrical object into a water tank that stores water at approximately the same water level as the pile agent. A method for cooling a thermoplastic resin cylindrical object according to claim 1, characterized in that the cooling method comprises: 3 In an extruder equipped with a pinch roller in a water tank that pulls out a thermoplastic resin cylindrical object extruded from an annular slit of a die at a position below the die, the cylindrical object is placed above the die and the pinch roller. The cylindrical body is surrounded by a weir having an overflow pipe so that the cooling water flows down to the water tank in the form of a film of uniform thickness on the outer circumferential surface of the cylindrical body, and the die supplies gas at a predetermined pressure into the cylindrical body. The weir has an inner circumferential wall parallel to the cylindrical object with a gap therebetween, and an outer circumference of the inner circumferential wall at a position higher than the upper edge of the inner circumferential wall. A water supply pipe that supplies cooling water is connected to a space formed by an outer circumferential wall having an edge and a bottom wall sealing between the inner circumferential wall and the lower edge of the outer circumferential wall, and the inner circumferential wall of the weir has a cylindrical shape. It is formed by connecting a short tube that contacts and guides an object at an upper position, and a long tube that maintains a gap with the cylindrical object below the short tube and has an opening at the top that communicates between the gap and the space inside the weir. A cooling device for a thermoplastic resin cylindrical object, characterized in that: 4 A pinch roller is placed in a water tank maintained at a constant water level, and a pile agent is stored in the lower part of the cylindrical object, and the liquid level of the pile agent is adjusted based on a sensor that detects this. The cooling device for a thermoplastic resin cylindrical object according to claim 3, wherein the cooling device is maintained at the same level as the water surface. 5. The thermoplastic resin cylindrical shape according to claim 4, wherein the short cylinder and the long cylinder are connected by a groove-shaped ring that opens in a radial inward direction and is disposed between the two cylinders. Cooling device for things. 6. The cooling device for a thermoplastic resin cylindrical object according to claim 4 or 5, wherein the short cylinder has a chamfered inner surface at its upper end. 7. The cooling device for a thermoplastic resin cylindrical object according to claim 5, wherein the groove-shaped ring has a plurality of holes bored on its back surface. 8. The cooling device for a thermoplastic resin cylindrical object according to claim 5, wherein the groove-shaped ring has a plurality of holes bored in its upper surface. 9. Claim 4 or 5, characterized in that the long tube has a downward groove cut on its inner surface.
A cooling device for a cylindrical thermoplastic resin article as described in 2. 10. The cooling device for a thermoplastic resin cylindrical object according to claim 9, wherein the groove on the inner surface of the long cylinder is spiral-shaped. 11 The distance between the cylindrical object and the inner peripheral wall of the weir is 1 to 15 mm.
A cooling device for a thermoplastic resin cylindrical object according to claim 3 or 4, characterized in that: 12. The cooling device for a thermoplastic resin cylindrical object according to any one of claims 4 to 6, wherein the short cylinder has a length of 1 to 30 mm. 13 Claim 4, characterized in that the short tube and the long tube are connected with a distance of 1 to 20 mm.
A cooling device for a thermoplastic resin cylindrical object according to item 1 or 5. 14. Claims 4, 5, 6, 9, 10, 12, and 13, characterized in that the short tube and the long tube are each divided into two parts. A cooling device for a thermoplastic resin cylinder according to any one of the items.