JPS5932301B2 - Hatsuposhi Toseizou Yourei Yakling - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cooling ring for manufacturing foam sheets.

Conventionally, a foamable thermoplastic resin is passed through an extruder and extruded into a cylindrical shape through an annular slit die provided at the tip of the extruder to start foaming. In a method of producing a foam sheet by blowing air through a slit die to expand the cylindrical body in the diametrical direction, the cylindrical body is taken to a cooling drum, and cooled and solidified. Airicida has been proposed as a cooling device to provide this.

However, in order to add a skin layer that suppresses foaming to the surface of the foam sheet by using the conventional air cider, the air cider is installed between the bubble growth force ν', that is, at a position close to the annular slit die. When cooling air is blown from the air slit die, for reasons that are unclear, the cylindrical body extruded from the annular slit die is moved from the position where foaming started to the position on the way to the cooling drum. Since ``undulations'' are generated in the diametrical direction, the cooling air blown from the air ferns cools the ``undulated'' portions, and the distance between the crest and bottom of the ``undulated'' portions from the air ferns is large. As a result, the resulting foam sheet has thick and thin skin layers that alternate in the extrusion direction in the form of bands. There were flaws.

On the other hand, when observing the occurrence of the above-mentioned "waving", even if the air cider is installed in a position where the "waving" has disappeared, simply blowing air has a poor cooling effect, and the resulting foam sheet does not have the same effect as the above-mentioned skin. Although no bands were observed due to the thickness of the layer, the bubbles on the surface were large, and the skin layer was extremely thin and easily broken.

In addition, in the conventional method using an air ring, the surface smoothness of the obtained foam sheet differs between the surface cooled by the air ring and the surface cooled by the cooling drum. There were also some drawbacks.

In addition, in the conventional method using an air ring, the obtained foam sheet has a high chargeability, and in the production method using flammable gas as a blowing agent, generation of electricity between the foam sheet and manufacturing equipment or workers There is a risk of fire caused by sparks caused by the discharge, and the foam sheet has the disadvantage that dust tends to adhere to it. In view of these drawbacks, the present inventors have devised a novel cooling ring that has a greater cooling effect than a simple air ring, and by its use, it is possible to obtain a foamed sheet free of the above-mentioned drawbacks. That is, the present invention provides (1) between an annular slit provided at the tip of a foam extruder and a cooling drum provided for the purpose of expanding and cooling the resin cylindrical body extruded from the annular slit; In the cooling ring installed so as to circumscribe the resin cylindrical body, the surface in contact with the resin cylindrical body is smooth, has an annular flow path through which a temperature regulating fluid can pass, and has an air supply. A cooling ring for manufacturing a foamed sheet, characterized by having a port, an annular air reservoir connected to the air supply port, and an air outlet directly connected to the air reservoir, (2) manufacturing the foamed sheet according to (1) above. In this cooling ring, a spray nozzle is connected to an air supply port, and an air introduction port and a water introduction port are arranged on the spray nozzle.

In the cooling ring according to the present invention, the angle of the smooth surface in direct contact with the resin cylinder with respect to the extrusion axis is slightly open toward the cooling drum, or the surface is a part of the inner surface of the cylinder. A certain shape is preferable, and the air outlet has a shape in which water droplets dispersed in a mist form by a spray nozzle aggregate in an air pool to form large water droplets, and the water droplets are sprayed as they are onto the surface of the cylindrical body. It is preferable to have a guide groove for the water droplets so as not to cause the water droplets to flow, and it is also effective to provide a baffle plate for the purpose of making the amount of air blown into the air pocket uniform over the entire circumference of the outlet. However, if the amount of water dispersed in the air blown out from the air ring is small, the guide groove described above may not be provided.

Next, typical embodiments of the present invention will be described with reference to the drawings.

In FIG. 1, a cooling ring 1 has an annular flow path 2 through which a cooling medium passes, and a baffle plate 6 that stores air supplied from an air supply port 3 and is directly connected to an air outlet 5 to equalize the flow of air. In addition, the annular flow path 2 has a partition wall with a cavity 10 passing through the central axis and having a smooth inner surface.

In addition, in FIG. 2, the cooling ring 1 has an annular flow path 2 through which a cooling medium passes, and an air introduction hole 8 at an air supply port 3.
and a water guide hole 9, and a groove 11 for discharging water droplets adhering to the inner wall surface of the air reservoir 4 at a portion connecting the air reservoir 4 and the air outlet 5, and annular flow path 2
The partition wall has a cavity that passes through the central axis and has a smooth inner surface.

Next, the production of a foam sheet using the cooling ring shown in FIG. 1 will be described.

In FIG. 3, the resin cylindrical body 20 extruded from the annular slit portion 33 of the die 32 starts foaming, and at the same time generates undulations 7 in the diametrical direction as shown in FIG.

Here, at the same time as the resin cylindrical body 20 is extruded from the annular slit 33, a blow-off hole 1 is provided at the tip of an air conduit 16 passing through the cooling drum 15 into the internal cavity 21 of the resin cylindrical body 20.
Air is blown through 7 to expand the resin cylindrical body 20 in the diametrical direction, making it easier to take it into the cooling drum 15 and at the same time reducing the waving 7 to some extent. In the above state, the resin cylindrical body 20 is brought into contact with the inner smooth surface of the cooling ring 1 whose temperature is controlled by a cooling medium such as water passing through the annular flow path 2 to prevent the growth of air bubbles on the surface. Then, the air supplied to the air pocket 4 is blown from the air outlet 5 and taken over so as to cover the cooling drum 15.

The air blown into the cavity 21 in this way assists the expansion of the cylindrical body 20 and works to strengthen the contact between the cylindrical body 20 and the cooling ring 1, and furthermore, the air blown into the cavity 21 acts to strengthen the contact between the cylindrical body 20 and the cooling drum 15 and the cylindrical body. It acts as a lubricant between the bodies 20. Since the amount of air required to act as a lubricant is very small, it is adjusted by an exhaust valve 18 provided at the rear end of the cooling drum 15. The resin cylindrical body 20 thus taken up by the cooling drum 15 is indirectly cooled and solidified by a cooling medium such as water passing through the conduit 19, and smoothness is imparted to the inner surface. It is cut open by a blade (not shown) provided at the rear end and rolled up as a foam sheet.

The foamed sheet obtained by the above method has a skin layer uniformly applied over the entire surface of the sheet and has smooth surfaces on both the front and back surfaces.

Next, when a foam sheet is manufactured using a cooling ring as shown in Figure 2, not only can a thicker skin layer be added by blowing air containing water droplets onto the cylindrical body, but also the static electricity generated is discharged through the water droplets, resulting in a foamed sheet with little charge.

Next, an example in which a foamed sheet was manufactured using the cooling ring according to the present invention will be described.

Example 1 100 parts of polystyrene pellets containing 6% by weight of pentane were mixed with 1 part of talc and 0 each of sodium bicarbonate and taenoic acid.
．． Transfer 5 parts to a screwdriver with a diameter of 50 m and 1 L. The mixture was melt-kneaded in an extruder of L/D24 and extruded into a cylindrical body through a TfL0 annular slit die with a slit width of 0.5 mm and a slit diameter of 60 m provided at the tip of the extruder.

Next, air is blown into the inner cavity of the cylindrical body through a cooling drum to expand the cylindrical body in the diametrical direction, and then the resin is placed on the inner surface of a cooling ring with an inner diameter of 120 ml whose temperature is controlled by cooling water. The outer surfaces of the cylindrical bodies were brought into contact with each other, and air was blown from a cooling ring to suppress foaming on the surface of the resin cylindrical bodies, and the resin cylindrical bodies were taken to a cooling drum having an outer diameter of 150 mm. child\
The cylindrical body was cooled and solidified by circulating cooling water through the cooling drum, and the cylindrical body was cut open with a blade provided at the rear end of the cooling drum and wound up into a roll. The foam sheet thus obtained has a thickness of 1.0m7! It was a foam sheet with a foaming ratio of 10 times and a thick skin layer uniformly provided on both sides. Example 2 In Example 1, using the cooling ring shown in Figure 2, foaming was carried out by blowing air in which 409 water per cubic meter of air was dispersed in the form of a mist onto the cylindrical body. The sheet was manufactured.

The foam sheet obtained in this way has less static electricity during manufacturing,
Therefore, no electrical discharge occurred between the foam sheet and manufacturing equipment or workers, and no danger was felt even when flammable gas was used as a foaming agent.

Furthermore, the foamed sheet had a thickness of 0.6 mm, an expansion ratio of 8 times, skin layers of equal thickness on both sides, and a smooth surface.

Furthermore, when the front and back sides of the foamed sheet were printed separately using a gravure printing machine, the printing was extremely clear, with no breakage due to tension or bending during printing on both sides.

As described above, by using the cooling ring for producing a foamed sheet of the present invention, a thick and uniform skin layer can be provided to the foamed sheet, and the surface can also be made to have excellent smoothness.

Furthermore, according to the present invention, there is little static electricity during the production of foam sheets, and the risk of fire caused by discharge sparks is extremely low, making it possible to safely use flammable gas as a foaming agent. It's something you get.

[Brief explanation of the drawing]

FIG. 1 shows a cross section and a side surface of an example of a cooling ring according to the present invention in half, and FIG. 2 is a sectional view of only the main part of another embodiment according to the present invention. FIG. 3 shows a part of an apparatus for manufacturing a foam sheet using a cooling ring according to the present invention in a cross-sectional view and a side view, respectively;
FIG. 4 shows a cross section taken along the line AA' in FIG. 3. 1... Cooling ring, 2...
Annular flow path, 3...Air supply port, 4...
Air pocket, 5...Blowout port, 6...Baffle plate, 7...Spray nozzle, 8...Air introduction hole, 9...・Water introduction hole, 10...Cavity, 11...Groove, 15...Cooling drum,
16...Conduit, 17...Blowout hole, 18
... Exhaust valve, 19 ... Conduit, 20 ...
... Resin cylindrical body, 21 ... Cavity, 32 ...
...Die, 33...Annular slit.

Claims (1)

[Claims] 1. Expanding an annular slit provided at the tip of a foam extruder and a resin cylindrical body extruded through the annular slit,
A cooling ring installed externally on the resin cylindrical body between the cooling drum provided for the purpose of cooling, and having a smooth surface in contact with the resin cylindrical body, manufacturing a foamed sheet characterized by having an annular flow path through which air can pass, an air supply port, an annular air pocket connected to the air supply port, and an air outlet directly supplied to the air pocket. cooling ring. 2 Expanding the annular slit provided at the tip of the foam extruder and the resin cylindrical body extruded through the annular slit,
A cooling ring installed between a cooling drum provided for the purpose of cooling and circumscribing the resin cylindrical body has a smooth surface in contact with the resin cylindrical body, and has a temperature regulating fluid. has an annular flow path through which air can pass, and has an air supply port, an annular air reservoir connected to the air supply port, and an air outlet directly connected to the air reservoir, and a spray nozzle is connected to the air supply port. 1. A cooling ring for producing a foamed sheet, characterized in that the spray nozzle is connected with an air introduction hole and a water introduction hole.