JPH0767702B2 - Resin film heating device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating device capable of heating a belt-shaped resin film (or sheet) while continuously feeding it.

[0002]

2. Description of the Related Art When a thermoplastic resin film is continuously obtained by calendering, the edges (so-called "spots") on both sides of the film are often cut off because they do not have a specified thickness. It is made into a molding material again. The part that is cut and re-kneaded cannot be sufficiently kneaded until it is heated to an appropriate temperature (it causes defects in the molded product), so first send it to some heating device. To be

The heating device for the recycled film must be a device that can heat the strip-shaped film while continuously feeding it (preferably at the molding speed). This is because the cut film is usually a band having a width of about 200 mm and its length increases at the same speed as the production rate of the film by calender molding.

As a means for heating a belt-shaped resin film for such a purpose, there have been conventionally the following means.
That is, (a) a roll heating method in which a film is wound around the side surfaces of several heated rolls and the films are sequentially fed by rotating the rolls.

(B) A kneading extrusion method in which a film is placed in a continuous kneader having an extrusion screw, and the film is discharged to a kneading step with other materials while being heated by the shearing action of the screw.

C) An air heating method in which the film is sequentially fed into a natural convection type heating furnace (oven type) in which the internal air temperature is raised.

[0007]

The above-mentioned conventional heating means have the following disadvantages.

(A) In the roll heating method, the resin film is apt to adhere to the surface of the roll heated to a high temperature, so that the film may not be smoothly fed or may be cut. In addition, since the film stretches as it is heated and the temperature rises, it is necessary to delicately control the rotation speed of each roll in accordance with the stretching in each part. If the control is inadequate, the film becomes more prone to breakage, for the reasons given above.

(B) Since the kneading extrusion method heats a film based on shearing by an extrusion screw, it has low energy efficiency. In other words, a high-powered and expensive device is required as a screw drive source, and a considerable amount of energy (electric power, etc.) is consumed to drive the screw.
Both equipment and operating costs are high.

(C) The air heating method is advantageous in terms of equipment cost since the structure of the heating furnace is simple, but since the film is heated by natural convection heat transfer, the time required for heating becomes long. Therefore, it is not possible to feed the film at a desired speed, or an extremely long heating furnace is required. If the heating furnace becomes long, not only is it difficult to install, but special measures are required to prevent the film from sticking to the objects inside the furnace and to prevent the film from breaking. ) Is difficult to handle when passing through or when the film is cut.

An object of the present invention is to provide a heating device which does not have the above inconvenience.

[0012]

In the resin film heating apparatus according to claim 1 of the present invention , first, a) the furnace body is formed into a tubular shape, and b) along its longitudinal direction (axial length direction). A resin film feed-in port and a draw-out port are provided near each end in order to pass the resin film from the upstream side to the downstream side, and c) an inlet for hot air and an inlet for hot air, respectively. A discharge port is provided. The hot air here means high temperature gas forcedly flown into the furnace body.

With respect to this heating device, further, d) a resin film feeding port and a drawing port are provided at the most upstream end and the most downstream end of the furnace body so that the center lines of the openings coincide with the longitudinal direction of the furnace body. Each of them is formed, and e) a confluent pipe inclined so as to form an acute angle (about 30 ° or less) with the upstream side in the longitudinal direction of the furnace body is provided at the inlet of the hot air, and f) the outlet of the furnace is provided at the hot air outlet. A branch pipe that is inclined so as to form an acute angle (about 30 ° or less) with the downstream side in the longitudinal direction is provided.

Further, as described in claim 2 , the above
In addition to a), b), and c), g) make the longitudinal direction of the furnace body horizontal (not necessarily horizontal), and h)
Water passage (or other cooling medium passage) at the bottom of the furnace body
May be provided. Alternatively, as in claim 3, the above
This for a heating device according to claim 1 comprising a) to f).
It is also preferable to additionally equip g) and h).

Further, as in claim 4, the a).
In addition to b) and c), i) It is more preferable to provide a blowout port for compressed air toward the downstream side in the feeding port of the resin film. As described in claim 5, claims 1 to
This i) may be added to any of the three heating devices.

[0016]

The heating device according to claim 1 of the present invention has the above a).
As described in b), the resin film is heated by passing it through a cylindrical furnace body, and has a portion common to the conventional air heating method (shown in (c) above). Therefore, unlike the roll heating method (above)), the resin film rarely adheres to the roll or breaks, there is no difficulty in control, and it is different from the kneading extrusion method (above)). Equipment costs and operating costs are low.

In this heating device, an inlet and an outlet for hot air are provided as shown in c) so that the hot air can flow in the same direction as the resin film is sent. Therefore, 1) the resin film is heated quickly by forced convection heat transfer, which is significantly advantageous over the conventional air heating method (above C) in terms of heating efficiency and furnace compactness, and 2) furnace body Since the resin film can be smoothly fed regardless of whether the (longitudinal direction) is horizontal or vertical, it is unlikely that the resin film will break or that the films will adhere to each other or to other objects in the furnace. The hot air is obtained by heating the air with a dedicated heater or using waste heat from other equipment, and is forcibly sent to the inlet of the furnace body by applying an appropriate pressure with a fan or the like.

[0018] In the case of the heating apparatus according to claim 1, since the was carried over port and outlet of the resin film is provided as described above d), the film path before and after and the interior of the furnace body It is passed almost straight without bending. This means that the film, including the handling of the end portion (starting portion, that is, the lead portion of the film), can be passed through the furnace extremely smoothly.

Another function of the heating device of claim 1 is as follows.
As described above, despite the fact that the inlet and outlet of the resin film are open at the most upstream end and the most downstream end of the furnace body, there is little entrainment of outside air other than hot air and outflow of hot air. This is as in e) and f) above.
This is because the hot air inlet / outlet is formed as a confluent conduit that makes an acute angle with the longitudinal direction of the furnace body. Based on the fluid dynamics, when the inclination of the hot air inlet / outlet with respect to the longitudinal direction of the furnace body is about 30 ° or less, even if there is an opening at the most upstream end and the most downstream end of the furnace body, the outside air ( The amount of entrained cold air) and the amount of hot air leaked to the outside can be extremely reduced.

The heating device according to the second or third aspect of the invention is configured so as to avoid the adhesion of the resin film inside while facilitating the placement of the furnace body. That is, in this heating device, since the longitudinal direction of the furnace body is horizontal as described in g), it is easy to install the furnace body itself, and there is no need for a large height difference in the supply path of the resin film including the furnace body. Easy equipment layout. In a furnace body whose longitudinal direction is horizontal, the resin film tends to hang down and adhere to the bottom of the furnace body even when hot air is sent, but this device prevents the adhesion as described in h) above. This is because a water passage was provided at the bottom. If a cooling medium such as water is allowed to flow in this water passage, the temperature rise at the bottom is suppressed, and the resin film does not adhere even if it contacts the bottom.

In the heating device according to the fourth or fifth aspect of the invention, the end portion of the resin film can be easily passed through the furnace body by utilizing the compressed air outlet described in i). If you insert even a little edge of the film into the feed-in port and then forcefully blow compressed air from the above outlet (it is also effective to introduce hot air at the same time), the film edge will be that air (and hot air). This is because it reaches the outlet on the downstream side so as to be sent by. This action is useful not only in the end portion of the film but also in the case where the film is cut in the middle of the furnace body and when the cut portion is passed to the outlet. In such a device without a blow-out port, for example, 1) increase the amount of hot air when passing the end of the film, and send the end of the film to the downstream side of the furnace body by the blowing action of the hot air; It is possible to open the body once and grab the edge of the film with a hand and pass it through the furnace. However, in the case of 1), there is a disadvantage that a fan for hot air or the like requires a considerable spare capacity and the equipment cost is high, and in the case of 2), the manual work of the operator is complicated.

[0022]

1 to 3 show an embodiment of the present invention. This example relates to a production line for obtaining a PVC (vinyl chloride) film by calendering, and a heating device 10 is installed in a part of the line as shown in FIG.

This production line is generally composed of a kneading machine, a molding machine, and a recycling material collecting machine. First, as equipment for kneading, as shown in FIG. 1, a Banbury (kneading machine) 1, a drop roll (warmer roll or kneading machine) 2, a strainer 3 and the like are installed, and by these, about 160 ° C. (about 430K ) PVC kneaded material Aa is prepared. Following the strainer 3, a calendar roll 4, a take-off roll 5, a cooling drum 6 and the like are arranged as molding equipment. By these, the kneaded material Aa is formed into a film and cooled to room temperature. Since the thickness of the formed PVC film material is uneven on both sides, that is, at the widthwise both ends of the PVC film material having a width of about 200 mm,
It is cut at the end of the drum 6a, and only the middle portion is wound up on the winder 7 as the PVC film product Ab.

The cut portion of the above-mentioned Mimi becomes a band-shaped film Ac, which is collected as a recycled material and returned to the above-mentioned drop roll 2. As a device for collecting this (two sets are arranged in parallel corresponding to the Mimi on both sides), there are a transport duct 8 and a transport roll 9, but at a position immediately before the drop roll 2 is 20 ° C. (about 290 K). A heating device 10 is arranged to heat the front and rear films Ac to 100 ° C. (about 370 K) or more. In addition, in this example, the portion of Mimi has a width of about 200 mm (above), a thickness of about 0.1 mm, a specific gravity of 1.4, and a specific heat of 0.25 kcal / kg · ° C.

The heating device 10 is, so to speak, a forced convection type air heating method, and has a cylindrical furnace body 11, a take-up means 16 behind it (downstream according to the flow of the film Ac), and the inside of the furnace body 11. 1 to send hot air to the room (forced convection)
7 and the heater 18 and the like. The film Ac is passed inside the furnace body 11 together with the hot air of about 180 ° C. (about 450 K), and the film Ac is rapidly heated by the forced convection heat transfer from the hot air. The heating device 10 will be described in detail below.

First, the furnace body 11 was installed so that the longitudinal direction (axial direction of the cylinder) was horizontal. Because the total length of the furnace body 11 is about 5 meters, it fits comfortably on the production line even if it is horizontal, and the horizontal installation is easier and more stable. According to the calculation by the inventors, it has been found that the length of the heating furnace needs to be 20 meters or more when the conventional natural convection air heating method is applied to the production line equivalent to this embodiment.

A film Ac feeding port 12 (see FIG. 2) is provided at the most upstream end of the cylindrical furnace body 11, and the most downstream end is a full-open film without end plates attached to the end. The outlet 13 for Ac was used. The film Ac that is cut and then conveyed by the duct 8 or the roll 9 is
It enters into the furnace body 11 through the feed-in port 12, is heated in the furnace body 11, and is drawn out through the outlet port 13. Since the feed-in port 12 and the pull-out port 13 are opened on the axis of the cylindrical furnace body 11 and their respective center lines coincide with the axial length direction of the furnace body 11, the film Ac passed through the furnace body 11 is bent. There is no need, and the inside of the furnace body 11 can be fed very smoothly.

The hot air sent from the fan 17 and the heater 18 is introduced into the furnace body 11 from the inlet 14 on the upstream side, discharged from the outlet 15 on the downstream side, and circulated again to the heater 17 and the fan 18. The hot air was made to flow in the furnace body 11 along the flow of the film Ac from the upstream side to the downstream side at a flow rate of about 10 m / s, so as to promote smooth feeding of the film Ac.

The hot air is circulated because the thermal efficiency (the degree to which the amount of heat is effectively used for heating the film Ac) is higher than that of discharging it from the discharge port 15 to the outside. It is important not to enter the furnace body 11 and to prevent hot air from flowing to the outside as much as possible. With respect to the furnace body 11 having openings (feeding-in opening 12 and drawing-out opening 13) for the film Ac at the most upstream end and the most downstream end, it is necessary to pay particular attention to this point. Therefore, in this heating device 10, the introduction port 14
2 is configured as shown in FIG. 2, and the discharge port 15 is similarly configured (the inlet port 14 is inverted toward the downstream side).

That is, the inlet 14 is a box-shaped header 14
The inside of the header 14a is connected to the inside of the furnace body 11 through the four merging pipes 14b that are inclined vertically and horizontally. Since the inclination angle of each of the confluent pipes 14b with respect to the upstream side in the longitudinal direction of the furnace body 11 was set to 30 °, the hot air introduced via these flows back to the upstream side of the furnace body 11 and exits from the feeding port 12. The rate at which the outside air is sucked in reverse is extremely low in terms of hydrodynamics. According to the experiments conducted by the inventors, when the upstream end of the furnace body 11 is a full-face opening, the outflow amount of hot air or the inflow amount of outside air from the open end is about 10% of the total hot air amount, which is the same as in the present embodiment. When the feed-in port 12 having a small cross-sectional area is provided at the upstream end, it becomes smaller than that.

Regarding the discharge port 15 (detailed view is omitted),
Similarly, since the branch pipe that forms 30 ° with respect to the downstream side in the longitudinal direction of the furnace body 11 is provided together with the header, the flow of hot air from the downstream end (drawing port 13) is also small in a hydrodynamic manner. According to the experiment, the outflow rate is still about 10% of the total hot air volume. From the above points, the hot air (the amount of heat thereof) is effectively used to heat the film Ac, so that the heater 18 having a capacity of about 15 kW is sufficient. The fan 17
A 2.2 kW motor (not shown) is used to drive the motor, but when applying the conventional kneading and extruding method to a production line equivalent to this embodiment, it is necessary to drive the screw of the kneader 9
Since the power of 0 kW is required, it can be said that this heating device 10 is obviously excellent in energy saving characteristics.

As the furnace body 11 is installed horizontally, the bottom surface 11a of the furnace body 11 on which the film Ac easily hangs and has a contact has a water cooling structure as shown in FIG. That is, the water passage 11b is provided outside the bottom surface 11a, and the water injection port 11c and the drainage port (not shown) are provided integrally therewith. By filling and flowing water into this water passage 11b, the bottom surface 11a
Keep the temperature around 70 ° C (343K). In this way, the film Ac does not adhere to the bottom surface 11a, and smooth continuous operation can be continued.

A blowing means for compressed air is also provided at the feeding port 12. That is, as shown in FIG. 2, a plurality of outlets 12a that are inclined (however, the inclination angle is about 20 °) are opened on the inner wall surface that continues from the feed-in port 12 and the outer circumference is surrounded by a box 12b. Further, a pipe 12c for compressed air (about 7 kg≈0.7 MPa) was connected. This blowing means is provided so that the end portion (lead portion or cut end) of the film Ac is placed on the air flow and sent from the feeding port 12 to the drawing port 13.
A valve 12d attached to the pipe 12c by inserting the end of the film Ac into the inside of the pipe 12c.
When (Fig. 1) is opened, air is forced into the furnace body 11 (about 7
flowed at a flow rate of m / s) and deposited on the film Ac
Is sent to the outlet 13.

Immediately outside (downstream side) the pull-out port 13 of the film Ac, a take-up means 16 shown in FIG. 3 is arranged. This means 16 has a predetermined speed (about 80 m / min≈
Pinch roll (holding roll 16a and drive roll 16b) that pulls out the film Ac at 1.3 m / s)
And an impeller 16c and the like behind it are provided on the frame 16d. The pinch rolls 16a and 16b are
The film Ac is rotated at a line speed, that is, a speed (control speed) corresponding to the production speed of the film product Ab to continuously and smoothly draw out the film Ac. And the impeller 16c is about 105
The film Ac is supplied onto the drop roll 2 while rotating at a surface speed higher than the speed of the film Ac, that is, the speed of the roll 16b so that the film Ac heated to 0 ° C. (about 380 K) does not adhere to the surface.

Although not shown, the take-up means 1 is also provided.
It is advisable to place a film Ac detection means before and after the film No. 6. As the detection means, for example, an optical sensor that can know whether or not the film Ac is passing in front of it can be used. If it is determined that the film Ac has not passed, it is judged that the film Ac has been cut in the furnace body 11, compressed air is blown out by opening the valve 12d, and the cut end in the furnace is extended to the outlet 13 and the take-up means 16. Once sent, continuous operation will be possible again.

The transport duct 8 is configured to transport the film Ac by the action of compressed air, like the furnace body 11. That is, in the transport duct 8, the same outlet as compressed air as shown in FIG. 2 is formed at the upstream end 8a of the tubular duct together with the passage of the film Ac.

In the above embodiment, two sets of recovery devices such as the heating device 10 are arranged in parallel in correspondence with the fact that two strips of film Ac can be formed, but two sets are not necessarily indispensable. For example, by heating the furnace body 11 to have a wide width (through which two strips of the film Ac can pass), the heating device 1
This is because it is possible to set 0 as one set. Further, the heating device according to the present invention is not limited to the calendering line as in the examples. It can also be widely used when continuously heating a belt-shaped resin film (or sheet) for purposes other than those described.

[0038]

The heating device according to the first aspect of the present invention has the following effects. That is, 1) It is rare that the resin film is smoothly fed, the films are adhered to each other or the film and another object, or the film is cut.

2) There is no need for special equipment costs and operating costs, and there is no particular difficulty in control technology.

3) Since the resin film is rapidly heated, the film feeding speed can be increased and the furnace body can be made compact.

Furthermore, 4) Since the resin film can be passed substantially straight in the front and rear and inside of the furnace body without being bent, the feeding can be performed more smoothly.

5) Since the outside air other than the hot air is not entrained and the hot air is less outflowed, the thermal efficiency is excellent and the influence on the working environment such as the outside air temperature is small.

According to the heating device of claims 2 and 3, 6) the furnace body can be easily arranged, and the resin film is prevented from adhering to the inner surface (bottom surface) of the furnace body.

In the heating device according to the fourth and fifth aspects of the present invention, 7) The compressed air can be used to easily pass the end portion (lead portion or cut end) of the resin film into the furnace body.

[Brief description of drawings]

FIG. 1 is a drawing related to an embodiment of the present invention, and is an overall schematic diagram showing a PVC film production line including a heating device 10.

FIG. 2 is a cross-sectional view showing the structure of the heating device 10 near the upstream end thereof.

FIG. 3 is a side view showing the structure of the heating device 10 near the downstream end.

[Explanation of symbols]

 10 Heating Device 11 Furnace Body 11b Water Channel 12 Inlet Port 12a (Compressed Air) Outlet Port 13 Outlet Port 14 Inlet Port 14b Joining Pipe 15 Discharge Port Ac Resin Film

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-2-270539 (JP, A) JP-A-62-140672 (JP, A) JP-A-59-101390 (JP, A)

Claims (5)

[Claims] 1. A furnace body is formed in a tubular shape, and a resin film feed-in port and a draw-out port are provided in the vicinity of each end in order to pass the resin film through from the upstream side to the downstream side along the longitudinal direction thereof. In addition, a hot air inlet and a hot air outlet are provided on the upstream side and the downstream side, respectively , and a resin film feeding port and a drawing port are provided for each opening.
The top of the furnace body is aligned so that the center line is aligned with the longitudinal direction of the furnace body.
It is formed at the flow end and the most downstream end, and the hot air inlet is inclined at an acute angle to the upstream side in the longitudinal direction of the furnace body.
A confluent pipe is installed and the hot air exhaust port is located at the bottom of the furnace in the longitudinal direction.
A heating device for a resin film, characterized in that a branch pipe that is inclined at an acute angle to the flow side is provided . 2. A furnace body is formed in a cylindrical shape and is arranged along the longitudinal direction thereof.
The resin film inside from the upstream side to the downstream side.
In order to ensure that the resin film feed-in and
Provided near the section, and on the upstream side and the downstream side,
An inlet and an outlet for hot air are provided to make the longitudinal direction of the furnace body horizontal, and
The resin film is characterized by having a water passage in the bottom.
Heating device. 3. The heating apparatus for a resin film according to claim 1 , wherein the furnace body is made horizontal in the longitudinal direction and a water passage is provided at the bottom of the furnace body. 4. The furnace body is formed into a cylindrical shape and is arranged along the longitudinal direction thereof.
The resin film inside from the upstream side to the downstream side.
In order to ensure that the resin film feed-in and
Provided near the section, and on the upstream side and the downstream side,
An apparatus for heating a resin film, characterized in that an inlet for hot air and an outlet for hot air are provided, and an inlet for compressed resin is provided with an outlet for compressed air toward the downstream side. 5. A resin film feed-in port is provided on the downstream side.
4. A blowout port for compressed air directed to
A heating device for the resin film according to any one of claims.