JPS6311970B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to a method of cold molding plastics.

The present applicant has previously reported that in the inflation method, T-die method, etc. in molding plastic films or sheets, foaming of water or a foaming agent of an aqueous solution containing a surface modifier is applied to a still hot film or tube. Developed a method in which the film or tube is cooled by the latent heat of vaporization of the water bubbles, or an extremely thin film of a surface modifier is formed on the surface of the film or sheet at the same time as cooling.
The application was filed under No. 158864 (see Japanese Patent Application Laid-open No. 59-49937).

This invention is a further improvement of this method, in which the size of the bubbles is made almost uniform, secondary air is blown onto the bubbles to form a continuous film consisting of a large number of bubbles, and this is brought into contact with the plastic being molded. By doing so, the cooling speed can be adjusted and uniform plastics can be obtained. Another object of the present invention is to provide a method for cooling and molding plastics, in which a continuous and more uniform ultra-thin film made of a surface modifier can be molded simultaneously with cooling by containing a surface modifier in the foam.

The method of the present invention will be explained below with reference to the drawings. FIGS. 1 and 2 show an embodiment in which the present invention is applied to an inflation method.

First, to explain the device used in this invention, 1.
is an extruder, 2 is a ring die of this extruder 1, and 3 is a ring die of this extruder 1.
is an annular foam blowing device provided below the ring die 2; 4 is a stabilizing plate with an inverted "C" cross section provided below the foam blowing device 3; and 5 is a stabilizer plate provided below this stabilizing plate 4. A pinch roller 6 is an annular solution storage tank provided in the foam blowing device 3, and 7 is a small diameter pinch roller consisting of two closely facing plates extending from one side of the inner periphery of the solution storage tank 6 to the top. 8 is water that has entered the solution storage tank 6, and 9 is a primary air blower pipe, which enters the solution storage tank 6 through a hole bored in the wall between it and the lower part of the solution storage tank 6. Primary air is blown into the ivy water 8 to form foam. Reference numeral 10 denotes an annular air circulation chamber provided above the solution storage tank 6 of the foam blowing device 3, and this air circulation chamber 10 has a secondary air inlet 10a at an appropriate location on the upper part of the outer peripheral wall of the foam blowing device 3. The foam blowing device 3 has a blowing outlet 10b at the upper part of the entire inner circumference. The upper end opening of the narrow diameter portion 7 provided as described above is located facing the lower part of the air outlet 10b. Inside the air circulation chamber 10, an annular partition wall 10c hangs downward from the top plate, and the secondary air that enters the air circulation chamber 10 hits this partition wall 10c as shown by the arrow in FIG. It goes under the partition wall 10c and reaches the air outlet 10b. The air ventilation diameter l ₁ in this air circulation chamber 10 is extremely larger than the vertical width l ₂ of the outlet 10b. Reference numeral 11 denotes an annular foam receiving plate provided below the foam blowing device 3.

Next, to explain the method of the present invention, the tube 12 is extruded from the ring die 2 of the extruder 1, passes through the annular hole of the foam blowing device 3, is guided by the lower stabilizing plates 4, and is guided by the pinch roller 5, 5, at which point the tube 12 is folded flat and wound into a roll. On the other hand, air is sent from the primary air blowing pipe 9 into the water 8 in the solution storage tank 6 to create bubbles in the solution storage tank 6. This foam 13 rises inside the narrow diameter section 7 by the primary air and reaches the upper opening of the narrow diameter section 7. On the other hand, secondary air is sent into the air circulation chamber 10 from the secondary air inlet 10a. As described above, the secondary air flows in the air circulation chamber 10 as shown by the arrow in FIG. 2 and is blown out from the outlet 10b. Since it is small, the flow of secondary air at the outlet 10b is extremely fast and blows away the foam 13 discharged from the upper end opening of the narrow diameter portion 7. This results in foam 1
3 becomes a large number of minute foams 13, and this process is performed continuously to form a continuous film consisting of a large number of foams 13, which flows out from the entire inner circumference of the foam blowing device 3 like a waterfall. A continuous film made up of a large number of foams 13 comes into contact with the outer periphery of the tube 12 that passes through the inner periphery of the foam blowing device 3. The tube 12 is extruded from the ring die 2 and is still in a molten state, and the bubbles 13 on the surface of the continuous film evaporate immediately upon contact with the tube 12. The tube 12 is cooled by the latent heat of vaporization at this time, and this continues to cool the entire outer circumference of the tube 12.

In this invention, water is made into a foam made of an extremely thin film, and this is brought into contact with the tube 12, and the tube 12 is cooled using the latent heat of vaporization.
Of course, the amount of water used is extremely small and the cooling effect is high. In addition, in this invention, the foam 13 discharged from the upper end of the narrow diameter portion 7 is made into a large number of uniform micro foams 13 by secondary air, and a continuous film made up of the large number of foams 13 is formed, which flows out from the blower port 10b. Tube 1 of these continuous films
2, the periphery of the bubble 13 in contact with the tube 12 on the surface of the continuous membrane is covered with other bubbles 13, and since air is contained within the bubble 13, these act as a heat insulating material and the bubble 13 is The thin film evaporates extremely quickly. Although the heat absorption due to the vaporization of this thin film of foam 13 is small, the tube 12 is secretly cooled because a large number of foams 13 are vaporized continuously. As described above, in this invention, by adjusting the volume, speed, etc. of the secondary air, the size of the bubbles and the blowing speed can be controlled, and thereby the cooling speed can be adjusted, and the orientation of the molecules in the tube 12 can be adjusted. Further, as the tube 12 descends, a large number of bubbles forming a continuous film flow down, so that the contact range of the bubbles 13 becomes larger, and a larger number of bubbles 13 come into contact with the tube 12 and are vaporized.
Therefore, the outer periphery of the tube 12 is reliably cooled.
Furthermore, since the large number of bubbles that come into contact with the entire outer circumference of the tube 12 are uniform in size as described above, the tube 12 is uniformly cooled.

FIG. 3 is almost the same as the embodiment shown in FIG. 1, but the outer periphery of the tube 12 extruded from the ring die 2 of the extruder 1 is cooled by an air-cooled primary cooler 14, and the portions of the tube 12 after the frost line are cooled. The above-mentioned foam blowing device 3 is installed in the tube 12, which is solidified on the outside but still has heat inside (for example, in the case of polyethylene, the temperature is above the second order dislocation point).
It is for cooling. Further, FIG. 4 shows a forming method in which a film 17 extruded from a die 16 of an extruder 15 is pulled with a pinch roller 18 and wound into a roll shape in a T-die method.
A box-shaped foam blowing device 3' and a plate-shaped foam receiving plate 11' are provided on both sides of the film 17 extruded from the film 17, thereby bringing bubbles into contact with both sides of the film 17 and cooling the film 17. be. In addition, in this T-die method, the die 1 of the extruder 15
The foam blowing device 3' and the foam receiving plate 11' may be provided only on one side of the film 17 extruded from the film 17, and the film 17 may be cooled only from one side. Further, in FIG. 5, the foam blowing device 3' and the foam receiving plate 11' are provided on both sides of the plastic filament 22 extruded from the die 21 of the extruder 20, thereby reducing the heat during molding. The filament 22 is cooled.

Of course, the embodiments shown in FIGS. 3 to 5 described above have the same effects as the embodiments shown in FIGS. 1 and 2 described above.

In addition, an aqueous solution or aqueous dispersion containing a surface modifier such as an antistatic agent is put into the solution storage tank 6, and this is made into a large number of foams, and the plastic film, tube, and the like that are being molded in the same manner as in the above embodiments. It is also possible to form a continuous film consisting of a large number of these bubbles on a filament, etc., and bring it into contact with the surface of the plastic, and simultaneously form a film made of the above-mentioned surface modifier on the surface of the plastic while cooling. In other words, when the foam containing the surface modifier comes into contact with the film, tube, filament, etc., the moisture therein instantly evaporates as described above, and the surface modifier is applied to the surface of the film, tube, filament, etc. at the same time as it cools. is attached. Because of the continuous film, a large number of bubbles come into continuous contact with the entire surface of the film, tube, filament, etc., so a uniform and continuous film made of the surface modifier is formed on the surface of the film, tube, filament, etc. . In this case as well, according to the method of the present invention, the contacting bubbles are uniform in size and are brought into contact continuously, so that the coating made of the surface modifier also becomes more uniform.

The surface modifier herein includes various agents such as an antifogging agent, a fungicide, and a rust preventive agent in addition to an antistatic agent.

In addition, in the above examples, in order to make a large number of foams from an aqueous solution or aqueous dispersion containing water and a surface modifier, a foaming agent such as a surfactant is mixed in, and the mixture is stirred at high speed with a machine or a gas such as air is added. There are ways to blow it in.

As described above, in this invention, foam made of water or the like passes through a narrow diameter part and is discharged from the opening of this narrow diameter part, and is blown away by secondary air, so that the foam becomes many small bubbles and flies. A continuous film consisting of a large number of bubbles is formed by continuing the process. Because this continuous film is brought into contact with the plastic being molded, the foam that comes into contact with the plastic is covered with other surrounding foam and the air inside the foam, which acts as a heat insulator and prevents the foam from vaporizing. promoted. Therefore, the cooling speed can be accelerated, and by adjusting the volume and speed of the secondary air, the molecular orientation of the plastic can be adjusted. Moreover, when the foam contains a surface modifier, a film made of the surface modifier is formed on the surface of the plastic at the same time as the cooling, but since the foam is uniform in size, the film formed is uniform. Become something.

[Brief explanation of the drawing]

FIG. 1 is a partial end front view showing an embodiment of this invention, FIG. 2 is a sectional view of a main part showing an apparatus used in this invention, and FIGS. 3 to 5 are respective examples of other embodiments of this invention. FIG. In the figure, 1 is an extruder, 3 is a foam blowing device, 6 is a solution storage tank, 7 is a narrow diameter part, 8 is water, 9 is a primary air blowing pipe, 10 is an air circulation chamber, 10b is an air blowing outlet, 12 is tube and 13 is foam.

Claims (1)

[Claims] 1. Water is made into a large number of bubbles by an appropriate method, these bubbles are discharged from an opening at the upper end of the narrow diameter part through a narrow diameter part, and a second wave is generated from a direction substantially perpendicular to this opening. Plastics characterized by cooling the plastic by blowing air to form a continuous film consisting of a large number of bubbles blown away and bringing this continuous film into contact with the surface of the plastic that is still hot during molding. cooling molding method. 2. Aqueous solution or aqueous dispersion containing an appropriate surface modifier is made into a large number of foams by an appropriate method, these foams are passed through the narrow diameter part and discharged from the upper end opening of the narrow diameter part, and the foam is discharged from the opening at the upper end of the narrow diameter part. Secondary air is blown from a perpendicular direction to form a continuous film consisting of a large number of blown bubbles, and the continuous film is brought into contact with the surface of the plastic, which is still hot during molding, thereby cooling the plastic at the same time. A cooling molding method for plastics, characterized by forming a film made of the above-mentioned surface modifier on the surface.