JPH0225775B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a resin cooling device used in manufacturing sheets or films of thermoplastic resin, and particularly to a resin cooling device that increases the flow rate of a cooling liquid and This invention relates to a resin cooling device that eliminates stagnation, improves cooling efficiency, and improves quality such as transparency.

[Prior art] Crystalline resins such as polypropylene are used as thermoplastic resins when extruding thermoplastic resins using a T-die or inflation die of an extrusion molding machine to produce various sheets or films. In this case, a transparent sheet or film cannot be obtained unless crystallization is prevented by rapid cooling below the melting point of the resin. For this reason, the resin cooling step has been an essential step in producing sheets or films. As a cooling means in this cooling process, a water cooling method is often adopted.

However, although this water cooling method has a relatively large cooling effect compared to other conventional cooling methods, when the high temperature resin extruded from the die comes into contact with cooling water, the water partially boils and evaporates. However, there are drawbacks such as partial cooling, uneven cooling due to ripples and shaking of the water surface, occurrence of haze spots due to insufficient cooling, and uneven or decreased thickness, transparency, and gloss.

Therefore, in order to eliminate the drawbacks of the above-mentioned water cooling method, cooling water is poured into the slit or into the cylindrical part.
Various apparatuses have been proposed for water cooling in which the molten resin is cooled by passing it through the slit or the cylindrical part. The present applicant also proposed this type of cooling device in Japanese Patent Application Laid-Open No. 60-236719.

[Problems to be solved] However, in the cooling equipment for carrying out the above-mentioned water cooling method, it is difficult to control the cooling liquid to prevent it from stagnation, and it is difficult to control the cooling liquid to prevent it from stagnation. It was difficult to obtain film. In addition, the cooling device proposed by the applicant is
Although it has an excellent effect when the flow rate of the cooling liquid is slow, that is, when cooling thin sheets or films, the cooling effect is insufficient when producing thick sheets at high speed. Therefore, it was not always possible to achieve satisfactory cooling.

The present invention has been made in view of the above-mentioned circumstances.It is an object of the present invention to significantly improve cooling efficiency by smoothly and rapidly flowing down the cooling liquid, and to perform sufficient cooling even with thick sheets. The purpose is to provide a resin cooling device that can

[Means for Solving the Problems and Effects] In order to achieve the above object, the resin cooling device of the present invention is a device that cools the resin extruded from the extruder die by bringing it into contact with the cooling liquid flowing down in the lower part of the cooling liquid flow. , the channel for supplying the coolant to the lower part of the coolant flow is formed in an inclined manner, and the inclined channel is provided with a porous flow regulator, and if necessary, the channel can be formed into a V-shape or a funnel-shape. It is formed in

With this configuration, the resin can be efficiently cooled in a stable state, and a sheet with high transparency and excellent surface properties, especially a thick sheet, can be obtained.

There are no particular restrictions on the resin that can be used in this cooling device, and examples include polypropylene, random copolymers of propylene and other α-olefins, high-density polyethylene, low-density polyethylene, and ethylene-α-olefin copolymers. Examples include crystalline resins such as LLDPE, polyester, and polyamide.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows a cooling device of a first embodiment for cooling a film-like thermoplastic resin extruded from a T-die.

In FIG. 1, 1 is a film-like thermoplastic resin, which is extruded from a T-die 2 in a molten state.
Reference numeral 10 denotes an upper water tank, which is composed of a first water tank 11 having a V-shape as a whole, and a second water tank 15 provided below the first water tank 11. First water tank 11
is provided with a first slit 12 in its center for passing the thermoplastic resin film 1 therethrough. This first slit 12 forms the lower part of the coolant flow, and in order to allow the coolant to flow sufficiently without causing turbulence, as shown in FIG.
The opening degree b should be in the range of 1 mm to 20 mm, and the length h should be in the range of 20 mm to 20 mm.
It is formed to be 200 mm, preferably within the range of 30 mm to 100 mm.

The flow path portion of the first water tank 11 through which the cooling liquid flows is formed by two inclined plates 13 that face each other with the first slit 12 in the center and are lowered toward the first slit 12 side. Inclination angle θ of this inclined plate 13
The temperature may be within the range of 2 degrees to 60 degrees. If this range is set, the cooling liquid can flow rapidly without turbulence, and the thermoplastic resin 1 introduced into the first slit 12 can be You can flow without hitting too hard. To make this more reliable, the inclined plate 1
It is preferable that the inclination angle θ of No. 3 is within the range of 3 degrees to 30 degrees. Furthermore, it is preferable that the two inclined plates 13 have the same inclination angle in order to maintain a balance in the flow rate, flow velocity, etc. of the cooling liquid flowing into the first slit 12.

Further, the connecting portion between the first slit 12 and the inclined plate 13 is set at a right angle or rounded with a small diameter, that is, the connecting portion diameter R is set to 0 to 10 mm. At this time, the water level of the coolant flowing into the first slit 12, which is the lower part of the coolant flow in the first water tank mentioned above, is set in the range of 2 mm to 10 mm, and is generally preferably 7 mm or less. In this way, the inclined plate 1
The cooling liquid flowing from the first slit 12 smoothly changes its direction in the same direction as the introduction direction of the film-like thermoplastic resin at the slit introduction part, and flows parallel to the film-like resin 1 into the inside of the first slit 12 without stagnation. flows smoothly into the If the water level of the coolant exceeds 10 mm, boiling spots, haze spots, curls, etc. will occur on the sheet, and the total haze will also increase, resulting in unfavorable results.

Furthermore, the first water tank 11 is provided with multiple porous flow regulators 14 to prevent the cooling liquid supplied to the first slits 12 from undulating or shaking, and to ensure that the thermoplastic resin film 1 is uniformly distributed without any undulations. It is designed so that a suitable water flow and amount of water can be obtained.

The second water tank 15 has a first slit 1 in its center.
A second slit 16 is provided which is continuous with the second slit 2. The second slit 16 has a wider opening than the first slit 12 and is formed to surround the tip of the first slit 12. In the second slit 16, new cooling fluid is added to the cooling fluid that has flowed down the first slit 12, and the thermoplastic resin film 1 is subjected to secondary cooling. Note that the same type of cooling liquid is used to flow into the first slit 12 and the second slit 16. 17 is a film-like thermoplastic resin 1 placed in an upper water tank 1.
This is a guide roll for pulling out from zero.

20 is a lower water tank, which is provided below the upper water tank 10. A narrow pressure roll 21 is disposed in the lower water tank 20, which compresses the thermoplastic resin film 1 to remove the film of water on the sheet surface, and constantly slits the thermoplastic resin film 1. Position it in the center and run at a constant speed. As the narrow pressure roll 21, a metal roll, a rubber roll such as silicone rubber, or a combination thereof is used.

22 is a take-up roll that pulls out the cooled thermoplastic resin film 1 from the lower water tank 20 and sends it to a secondary process. 23 is an overflow plate installed in the lower water tank 20,
The coolant level in the water tank 20 is kept constant. 24
is a pump that circulates the cooling liquid cooled to a predetermined temperature by the cooler 25 to the first water tank 11 and the second water tank 15 of the upper water tank 10.

Next, a method using the apparatus of the first embodiment will be explained.

A thermoplastic resin film 1 extruded from a T-die 2 is introduced into a first slit 12 of a first water tank 11 through which a cooling liquid is flowing. As described above, when the coolant is poured into the first water tank 11 at a water level of 2 mm to 10 mm, the coolant flows smoothly at the contact position with the film-like thermoplastic resin 1 without stagnation. Note that water is generally used as the coolant, and additives such as freezing point depressants, surfactants, thickeners, and rust preventives are mixed therein as necessary.
The temperature of the cooling liquid is 50°C or less, and from the viewpoint of cooling efficiency, it is preferably 20°C or less.

The thermoplastic resin film 1 undergoes primary cooling while passing through the first slit 12. That is,
Heat is absorbed by the cooling liquid flowing parallel to both sides of the film-shaped thermoplastic resin 1, and cooling is performed. In this case, since a large amount of cooling liquid can flow, the cooling efficiency is very high. The flow rate of the coolant flowing through the first slit 12 is preferably the same as or faster than the traveling speed of the film-like thermoplastic resin 1, preferably at least 1.5 times the traveling speed.

When the film-like thermoplastic resin 1 passes through the first slit 12 and is sent below the first slit 12,
Secondary cooling takes place in the second slit 16. That is, the cooling fluid that has flowed through the first slit 12 and the new cooling fluid that has flowed through the second water tank 15 contact both surfaces of the film-shaped thermoplastic resin 1 in a mixed flow state to perform cooling. In this case, the coolant that has flowed through the second slit 16 is lower in temperature than the coolant that has flowed through the first slit 12, so the secondary coolant in which they are mixed is also lower in temperature than the coolant that has flowed through the first slit 12. , further increasing cooling efficiency.

As described above, the thermoplastic resin film 1 cooled in the upper water tank 10 is passed through the cooling liquid in the lower water tank 20 by the narrow pressure roll 21 and the take-up roll 22 to perform tertiary cooling. . After that, it is sent to a secondary process, where after draining the cooling liquid (water), heat treatment, light stretching, rolling, etc. are performed as necessary.

A more specific summary of the results obtained by the method using the above device is as follows.

Results obtained by the method using the example device Conditions: Homopolypropylene resin (density 0.91
g/cm ³ , MI2g/10min, manufactured by Idemitsu Petrochemical Co., Ltd. Product name: Idemitsu Polypro F200 S) using a T-die extrusion device (extruder 90mmφ, L/D28, die width 730mm, die lip opening 2mm, lip heater included) Melt and knead at a resin temperature of 240℃ and a die lip temperature of 280℃ using
A transparent molten resin film (film-like thermoplastic resin) was extruded. Next, this molten resin film is poured into the first water tank 11 (first slit: length h = 50 mm) in the upper water tank 10.
mm, opening b=3mm, coolant: normal water, water level 5mm,
Water temperature 4℃, porous fluid regulation: 60 mesh wire mesh, 2 layers, 4 layers Inclined plate: Incline angle θ = 30 degrees, connection diameter R = 3
mm) and quenched, then heat treated at 120℃, polypropylene sheet (thickness 0.5mm)
was obtained at a molding speed of 8 m/min.

Result: As a result, a sheet with a haze level of 8.0% (internal haze level 6.0%) according to the ASTM D 1003 standard could be obtained.

Comparative Example Results A polypropylene sheet was obtained in the same manner as above except that the angle of inclination θ of the inclined plate of the first water tank was set to 0, that is, horizontal. As a result, the haze level of the sheet was 13.0% (internal haze level 8.0%).

As described above, by using the device of this embodiment, the cooling liquid can be rapidly flowed without stagnation, and the film-like thermoplastic resin can be cooled with a large amount of cooling liquid, thereby significantly improving the cooling efficiency. It is possible to obtain a sheet with high transparency and excellent surface properties. It is particularly effective for thick sheets and can increase the production speed. FIG. 3 shows a cooling device according to a second embodiment of the present invention used in the blown film production process.

In the case of this device example, the water tank 30 is formed into a funnel shape, and a cylindrical portion 31 is provided in the center thereof through which the inflation tube (bubble) extruded from the inflation die 4 passes. . This cylindrical portion 31 forms a lower part of the coolant flow, and is configured to allow the coolant to flow sufficiently without causing turbulence. The flow path portion of the water tank 30 through which the cooling liquid flows is formed by an annular inclined plate 32 that becomes lower toward the cylindrical portion 31 at the center. This inclined plate 32 also has an inclination that is substantially the same as that of the inclined plate 13 in the device of the first embodiment, and the connection portion with the cylindrical portion 31 has a diameter that is substantially the same as that of the device of the first embodiment. Thereby, the coolant can flow rapidly without causing turbulence, and can also flow without strongly hitting the bubbles 3 introduced into the cylindrical portion 31.

The water tank 30 also includes an annular porous fluid regulator 33.
are provided in multiple layers so as to surround the cylindrical portion 31.
This prevents the coolant supplied to the cylindrical portion 31 from undulating or shaking, and allows a uniform water flow and amount of water to be obtained with respect to the valve 3 without any undulations. In addition, in FIG. 3, 34 is an air ring for uniformly blowing air around the valve 3.

When cooling was carried out using the blown film cooling device constructed in this way under almost the same operating conditions as the first embodiment, it was found that the cooling efficiency was high and that the cooling liquid did not accumulate. Nakatsuta. As a result, as in the case of the apparatus of the first embodiment, a blown film with high transparency and excellent surface properties could be obtained.

The resin cooling device of the present invention can also be applied as a cooling device for various sheets and films other than the above-mentioned sheets and films.

[Effects of the Invention] As described above, according to the apparatus of the present invention, the flow of the coolant at the contact position between the molten resin and the coolant becomes extremely smooth, and the coolant can flow rapidly while preventing stagnation. This can significantly improve cooling efficiency.

[Brief explanation of drawings]

FIG. 1 shows a device diagram of a first embodiment of the present invention, FIG. 2 shows an enlarged view of the main parts of FIG. 1, and FIG. 3 shows a device diagram of a second embodiment of the present invention. 1, 3: Resin, 2, 4: T die, 10: Upper water tank, 11: First water tank, 12: First slit, 1
3: inclined plate, 14: porous rectifying plate, 15: second water tank, 16: second slit, 30: water tank, 31: cylindrical part, 32: inclined plate, 33: porous flow regulating plate.

Claims (1)

[Claims] 1. In an apparatus for cooling a resin extruded from an extruder die by bringing it into contact with a cooling liquid flowing down in a cooling liquid flow area, the flow path for supplying the cooling liquid to the cooling liquid flow area is inclined. 1. A resin cooling device characterized in that the slanted flow path is formed with a porous flow regulator. 2. The resin cooling device according to claim 1, wherein the cooling liquid flow lower part is formed in a slit shape. 3. The resin cooling device according to claim 1 or 2, wherein the inclined flow path is formed in a V shape. 4. The resin cooling device according to claim 1, wherein the inclined flow path is formed in a funnel shape. 5. The resin cooling device according to claim 1, 2, 3, or 4, characterized in that porous flow regulators are provided in multiple stages.