JP2000334811A - Casting apparatus for molding thin resin film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve product performance by preventing the entrainment of air between a thin film and a roll associated with the positional transfer of a vacuum box and preventing the vibration of the thin film. SOLUTION: A vacuum box 40 is composed of a housing 41 comprising upper walls 41a, 41b a rear wall 41c, and both side walls and labyrinth seals 42, 43, adheres to a casting roll 30, evacuates the inside, makes a space on the side of a suction port 40a vacuum, and increases the angle of a sheet 20 to the roll 30 to improve adhesion. A semicircular elastic seal member 50 is fitted to the upper wall 41a of the box 40. A silicon foam body 51a having a cavity part at the center is provided in the member 50, an insulating sheet is placed on the surface of the foam body 51a, and the whole is covered with a tetrafluoroethylene sheet. Even when the position of the box 40 is adjusted, a T-die 10 adheres to the upper wall 41a as shown by C by the elastic force of the seal member 50 to prevent the entrainment of air.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a casting machine for forming a thin film made of resin, which is provided with a vacuum box used for a film / sheet casting machine such as a biaxially stretched film machine, a non-stretched film machine and a sheet machine. Even if the position of the film is adjusted and changed, a seal portion is formed so as to reliably prevent air from entering between the casting roll and the thin film and prevent vibration of the film / sheet.

[0002]

2. Description of the Related Art FIG. 6 is a structural view showing a conventional film / sheet casting machine. A resin melted by an extruder (not shown) is fed from a T-die 101 to a film / sheet.
It is extruded as a sheet 102, wound tightly on a casting roll 103, and cooled. A vacuum box 104 is provided as an apparatus for stably adhering the film / sheet 102 to the casting roll 103. This vacuum box 104 is a vacuum pump 1
By suctioning at 05, the film / sheet 102 is provided immediately near the portion where the close contact with the casting roll 103 is started, and the air at the close contact portion is sucked from the gap provided over the entire width of the film / sheet 102, and the film / sheet is sucked. Air is prevented from being trapped between the sheet 102 and the casting roll 103, and the film / sheet 102 is stably adhered to the casting roll 103.

[0003]

According to experiments, when a film or sheet is formed by a casting machine using a vacuum box as shown in the above-mentioned conventional example, the type of material resin, the viscosity at the time of melting, the film The shape of the vacuum space formed by the molten film / sheet discharged from the T-die, the outer peripheral surface of the casting roll, and the tip of the vacuum box changes depending on conditions such as the thickness of the sheet and the molding speed. The presence or absence of inflow of outside air occurs. These influence the stable adhesion of the film / sheet, causing a problem that the film / sheet vibrates (oscillates) or is pulled into the vacuum box, and this effect is particularly large when molding at high speed.

Therefore, it is necessary to adjust the distance between the T-die and the casting roll or the distance between the film sheet and the tip of the vacuum box to set optimum conditions so as not to particularly cause the vibration of the film sheet. There is.
When this adjustment is made, a gap is created between the lower surface of the T-die and the upper surface of the vacuum box. If the gap is large, air flows through the gap to the suction port of the vacuum box, and due to this flow, the film / sheet vibrates. Therefore, there is a problem that it takes time to adjust the position of the vacuum box.

Accordingly, the present invention provides a casting apparatus for evacuating a thin film extruded from a die by winding it on a cooling roll by vacuuming with a vacuum box and bringing the thin film into close contact with the outer peripheral surface of the roll. It is an object of the present invention to provide a casting apparatus for forming a thin film made of resin, which has a vacuum box having a structure in which air does not flow between the lower surface of the die and the vacuum box even when the method is performed.

[0006]

The present invention provides the following means (1) and (2) to solve the above-mentioned problems.

(1) A die for extruding a molten resin as a thin film, a cooling roll for drawing the thin film extruded from the die onto an outer peripheral surface, cooling and sending the same, and a die independently of the die and for the cooling roll. A resin chamber, which is installed with a required seal gap therebetween and has a suction chamber for sucking air between the thin film and the cooling roll so that the thin film is in close contact with the cooling roll. In the casting apparatus for forming a thin film, a circumferential moving mechanism for moving the suction chamber along the circumferential direction of the cooling roll while maintaining the required sealing gap, and a width exceeding the entire width of the thin film attached to the suction chamber. And a semi-annular elastic sealing member body pressed against the die with elastic force, and an attachment for gripping lower portions at both ends of the elastic sealing member body. A resilient sealing member body, a base strip attached to the suction chamber, a semi-annular silicon foam fixed on the base strip and having a cavity in the center, and the silicon A gap between the upper surface of the suction chamber and the lower surface of the die, which is constituted by a heat insulating member surrounding the outer periphery of the foam and a Teflon sheet covering the entire surface of the heat insulating member. A casting device for forming a thin film made of a resin, characterized in that the sealing device is closed.

(2) In the casting apparatus for forming a thin film made of resin having the same configuration as described above, a circumferential moving mechanism for moving the suction chamber along the circumferential direction of the cooling roll while maintaining the required sealing gap. An annular elastic seal member body attached to the suction chamber, arranged over a width exceeding the entire width of the thin film, and brought into press contact with the die with elastic force; and a circular outer peripheral surface of the elastic seal member body. The elastic seal member body has an annular silicon foam having a cavity in the center, a heat insulating member surrounding the outer periphery of the silicon foam, A gap between the upper surface of the suction chamber and the lower surface of the die when the elastic seal member comes into contact with the die. The thin resin film molding casting apparatus characterized by closing the.

In (1) of the present invention, when the suction chamber is moved by the circumferential movement mechanism to adjust the position, the distance between the die and the upper surface of the suction chamber changes, but the suction chamber has a semi-annular shape. The elastic seal member main body is fixed by a mounting bracket, and the upper end thereof is pressed against the lower surface of the die with elastic force. Therefore, when the interval is widened, the silicone foam expands and maintains the contact. In addition, when the interval becomes narrow, the elastic seal member main body is further compressed and the contact is maintained. Therefore, the gap between the lower surface of the die and the upper surface of the suction chamber is constantly closed, so that air does not enter the gap from the outside, vibration of the thin film due to this is prevented, and a silicon foam is used. The service life of the elastic seal member body is prolonged by the heat insulating member made of the elastic body, the glass cloth material covering the surface, and the like, and the coating layer using the Teflon sheet covering the entire surface.

In (2) of the present invention, the main body of the elastic seal member has a ring shape, and the mounting member holds the outer periphery of the main body from both sides with a member having a curved surface conforming to the circular shape. Since the elastic seal member main body is fixed, the same effect as the effect of the invention (1) can be obtained, and the structure can be simplified.

[0011]

Embodiments of the present invention will be specifically described below with reference to the drawings. 1 to 4 are views showing a casting apparatus for forming a resin thin film according to a first embodiment of the present invention, and FIGS. 1 and 2 show a conventional example of FIG.
FIG. 3 is a detailed cross-sectional view of a portion where the vacuum box of the present invention is mounted, FIG. 3 is a perspective view near the side end of the vacuum box, and FIG. Will be described in detail.

FIG. 1 is a sectional view when the distance L between the T-die and the casting roll is small, and FIG. 2 is a sectional view when the distance L is large. In these figures, 10 is a T-die, 20 is a film / sheet, 30 is a casting roll, 40
Is a vacuum box, 50 is a vacuum box (suction chamber)
An elastic seal member (having a different size in FIGS. 1 and 2 but having the same number for convenience of explanation) attached to the upper surface of 40, and a suction duct 60.

The lower shape of the T-die 10 generally has a gradient that extends outward from a horizontal plane near the exit of the film sheet 20 as shown in FIG. 6 of the conventional example. Although a case is shown in which there is a gradient, there is no significant difference between the two.

The vacuum box 40 has upper walls 41a and 41a.
b, a housing 41 surrounded by a rear wall 41c and both side walls 41d (see FIG. 3), and labyrinth packings 42 and 43 (two pieces) fixed to lower portions of outer surfaces of the rear wall 41c and both side walls 41d (see FIG. 3). 3), and the front is open and the suction port 40 is formed by the outer peripheral surface of the casting roll 30.
The lower part is closed by the outer peripheral surface of the casting roll 30 to form a suction chamber 40b.

The labyrinth packings 42 and 43 are opposed to the outer peripheral surface of the casting roll 30 with a slight gap therebetween, and suppress the inflow of air from the lower portions of the rear wall 41c and the side walls 41d. However, the labyrinth packings 42 and 43 can arbitrarily adjust the gap with the outer peripheral surface of the casting roll 30.

The suction chamber 40b is connected to a vacuum pump (not shown in FIG. 6) via a duct 60 fixed to the upper wall 41b.
The entire vacuum box 40 is rotatably supported concentrically with the casting roll 30, though not shown in detail, so that it can be rotated along the outer peripheral surface of the casting roll 30. ing.

The elastic sealing member 50 is, as shown in FIG.
The seal member body 51 has a structure having excellent heat resistance, a large rebound resilience, and a small compressive residual strain. It will be described later. The lower portion of the elastic seal member 50 is sandwiched between rising portions of the mounting brackets 52 and 53, and is screwed to the upper wall 41 a of the vacuum box 40 with the mounting bolt 55 through the washer 54. In addition,
The female screw on the side of the upper wall 41a to be screwed with the mounting bolt 55 is blind screwed by the back plate 41e. The mounting screws 52 and 53 are attached to the mounting brackets 52 and 53 in order to replace and mount the sealing member body 51 having a different size. Slots 52a and 53a (see FIG. 3) are provided for 55.

Referring to FIG. 4, the internal structure of the elastic seal member 50 and details of the mounting bracket will be described more specifically. The elastic seal member 50 includes the seal member main body 51 and the mounting brackets 52 and 53 as described above. The seal member main body 51 includes a semicircular silicon foam body 51a having a hollow central portion, and a silicon foam body 51a. A semi-circular heat insulating member having an inner peripheral portion closely adhered to the outer periphery of the foam 51a, for example, a heat insulating sheet 51b made of glass cloth, a base strip 51c and a Teflon sheet 51d, and a silicon foam 51a
And the bottom surface in the circumferential direction of each of the heat insulating sheets 51b are:
The structure is such that it is placed on the center of a silicon rubber base strip 51c, which is slightly wider than the diameter of the heat insulating sheet 51b, and is entirely covered with a Teflon sheet 51d. The silicone foam 51a and the base strip 51c are bonded with an appropriate heat-resistant adhesive, and both ends of the heat insulating sheet 51b and the Teflon sheet 51d in the longitudinal direction are closed.

FIG. 5 is a cross-sectional view of a casting apparatus for forming a thin film made of resin according to a second embodiment of the present invention, showing the internal structure of a resilient seal member and mounting hardware. In the figure, an elastic seal member 150 is composed of a seal member main body 151 and mounting brackets 152 and 153. The seal member main body 151 has an annular silicon foam 151a having a hollow central portion, and the silicon foam 151a. A heat insulating sheet 151b made of, for example, a glass cloth and a concentric heat insulating member closely contacting the outer periphery of the Teflon sheet 1;
The Teflon sheet 151d has a structure that covers the whole, and both ends of the heat insulating sheet 151b and the Teflon sheet 151d in the longitudinal direction are closed.

The tip of the mounting bracket 152 is the seal member body 1
The mounting bracket 153 rises at an appropriate length with a radius slightly larger than the outer diameter of the seal member 51, and the mounting bracket 153 rises at a right angle in front of the seal member body 151, and the upper end has an appropriate length on the front side with a radius slightly larger than the outer diameter of the seal member body 151. The seal member main body 151 is held by the arc portions of both the mounting bracket 152 and the mounting bracket 153, and does not interfere with the lower surface of the T-die 10. The other parts are the mounting parts shown in FIG. Same as the bracket.

The structure of the seal member main body 51 of the first embodiment and the seal member main body 151 of the second embodiment described above enhances the strength against heat and friction of the outer peripheral portion by the above-described structure, and furthermore, the internal foaming. This helps to increase the repulsion of the part against permanent deformation.

Next, returning to FIGS. 1 and 2, the operation of the vacuum box 40 having the above configuration will be described. Molten resin is T die 10
, And formed into a film / sheet 20 and wound around a casting roll 30 to be cooled and formed. When the vacuum box 40 is not used, the molten film / sheet 20 is drawn by the casting roll 30 and runs in the direction indicated by the two-dot chain line A in FIG. 1 or FIG. Inconvenient such as entrainment or delay in contact with the casting roll 30 occurs, and the quality of the film / sheet 20 is reduced.

In order to prevent this problem, the rear side (the right side in FIGS. 1 and 2) of the film sheet 20 is set to a negative pressure, and the film sheet 20 is pulled rearward by a pressure difference from the front side to establish an attitude. The angle at which the film / sheet 20 enters the casting roll 30 is increased. In order to create a negative pressure on the rear side, a partition is formed on the rear side of the film sheet 20, and air between the film sheet 20 and the vacuum sheet 40 is sucked by the vacuum box 40. Otherwise, an unstable phenomenon occurs in which the film / sheet 20 and the air vibrate, and especially air flows in from the rear side (arrow B in FIG. 2).
If it does, it tends to be unstable.

For this reason, the vacuum box 40 is moved along the outer peripheral surface of the casting roll 30, and the tip is adjusted to an optimum position where the unstable phenomenon hardly occurs. For this adjustment, the position of the vacuum box 40 is changed. However, it is necessary to close the passage for inflow of air from outside into the space.

The elastic seal members 50 and 150 of the present invention
Plays a role of elastically deforming and automatically closing the gap even when the vacuum box 40 moves and the gap between the upper surface of the vacuum box 40 and the lower surface of the T-die 10 changes. The chain line C in FIGS. 1 and 2 indicates the moved elastic seal member 5.
Indicates 0.

As shown in FIGS. 1 and 2, when the relative position between the T-die 10 and the casting roll 30 is largely changed, the elastic sealing member 50 of the first embodiment or the elastic sealing member of the second embodiment is used. The member 150 is adjusted by replacing the member 150 with another one having a different size.

[0027]

The casting apparatus for forming a thin film made of resin according to the present invention comprises: (1) a die for extruding a molten resin as a thin film, and a cooling roll for drawing the thin film extruded from the die onto an outer peripheral surface, cooling and sending the thin film. And a gap between the thin film and the cooling roll so that the thin film adheres to the cooling roll while being installed independently of the die and with a required seal gap between the cooling roll and the die. A casting apparatus for forming a thin film made of resin, comprising: a suction chamber for sucking air; a circumferential moving mechanism for moving the suction chamber along a circumferential direction of the cooling roll while maintaining the required sealing gap; A semi-annular elastic seal member body attached to the suction chamber, arranged over a width exceeding the entire width of the thin film, and brought into pressure contact with the die with elastic force. Mounting brackets for gripping lower ends of both ends of the elastic seal member main body, wherein the elastic seal member main body has a base strip mounted on the suction chamber, and a hollow portion at the center fixed on the base strip. A semi-annular silicon foam having: a heat insulating member surrounding the outer periphery of the silicon foam; and a Teflon sheet covering the entire surface of the heat insulating member. Is used to close the gap between the upper surface of the suction chamber and the lower surface of the die. With such a configuration, even when the position of the suction chamber is changed by the circumferential movement mechanism in the adjustment of the position of the suction chamber for finding the optimum conditions to be performed prior to the start of the production operation of each thin film, the upper surface of the suction chamber is changed. The gap between the die and the lower surface of the die is automatically and reliably closed by the elastic sealing member body, and the film and
The vibration of the seat is prevented, the adjustment work is facilitated, and the production operation can be continued.

Further, the life of the elastic sealing member main body can be extended by the elastic portion using the silicone foam, the heat insulating member covering the surface of the silicone foam, and the covering layer using the Teflon sheet covering the whole.

According to a second aspect of the present invention, in the casting apparatus for forming a thin film made of resin, which is a premise of the first aspect, the suction chamber is moved along the circumferential direction of the cooling roll while maintaining the required sealing gap. A circumferential moving mechanism for moving, a ring-shaped elastic seal member main body attached to the suction chamber, arranged over a width exceeding the entire width of the thin film, and brought into pressure contact with the die with elastic force; and the elastic seal member. The elastic sealing member main body includes an annular silicon foam having a hollow center portion, and an outer peripheral surface of the silicon foam, the mounting member being in contact with a circular outer peripheral surface of the main body and gripping the main body from both sides. And a Teflon sheet coated on the entire surface of the heat insulating member, and the upper surface of the suction chamber is brought into contact with the die of the elastic seal member body. It is characterized by closing the gap between the lower surface of the i. With such a configuration, the same effect as the above (1) can be obtained, and further, the elastic seal member main body is annular, the shape is simplified, and the overall configuration of the apparatus is simplified.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a vacuum box in a casting apparatus for forming a thin film made of resin according to a first embodiment of the present invention, showing a case where a distance between a die and a casting roll is small.

FIG. 2 is a sectional view of a vacuum box in the casting apparatus for forming a thin film made of resin according to the first embodiment of the present invention, showing a case where a distance between a die and a casting roll is large.

FIG. 3 is a perspective view of a vacuum box in the casting apparatus for forming a thin film made of resin according to the first embodiment of the present invention.

FIG. 4 is a detailed sectional view of a vacuum box according to the first embodiment of the present invention.

FIG. 5 is a detailed sectional view of a vacuum box in a casting apparatus for forming a thin film made of resin according to a second embodiment of the present invention.

FIG. 6 is a configuration diagram of a conventional casting device.

[Explanation of symbols]

 Reference Signs List 10 T die 20 Film / sheet 30 Casting roll 40 Vacuum box 50, 150 Elastic seal member 51, 151 Seal member main body 51a, 151a Silicon foam 51b, 151b Heat insulating sheet 51c Base strip 51d, 151d Teflon sheet 52, 53, 152, 153 Mounting bracket

Claims (2)

[Claims] 1. A die for extruding a molten resin as a thin film,
A cooling roll that pulls the thin film extruded from the die onto an outer peripheral surface and cools and sends the thin film, and is installed independently of the die and with a required seal gap between the cooling roll and the cooling roll. A casting chamber for forming a thin film made of resin, comprising a suction chamber for sucking air between the thin film and the cooling roll so as to bring the thin film into close contact with the cooling roll; A circumferential moving mechanism for moving the suction chamber along the circumferential direction of the cooling roll while being disposed over a width exceeding the entire width of the thin film attached to the suction chamber and pressed into contact with the die with elastic force. A semi-annular elastic seal member main body, and mounting brackets for gripping lower ends of both ends of the elastic seal member main body. A base strip attached to the chamber, a semi-annular silicon foam fixed on the base strip and having a cavity in the center, a heat insulating member surrounding the outer periphery of the silicon foam, and an entire surface of the heat insulating member And a sealing device for closing the gap between the upper surface of the suction chamber and the lower surface of the die by contacting the elastic sealing member body with the die. 2. A die for extruding a molten resin as a thin film,
A cooling roll that pulls the thin film extruded from the die onto an outer peripheral surface and cools and feeds the thin film, and is installed independently of the die and with a required sealing gap between the cooling roll and A casting chamber for forming a thin film made of resin, comprising: a suction chamber for sucking air between the thin film and the cooling roll so that the thin film is brought into close contact with the cooling roll; A circumferential moving mechanism for moving the suction chamber along the circumferential direction of the cooling roll while being disposed over a width exceeding the entire width of the thin film attached to the suction chamber and pressed into contact with the die with elastic force. An annular elastic seal member main body, and a mounting bracket which is in contact with the circular outer peripheral surface of the elastic seal member main body and grips the main body from both sides. The material body is composed of an annular silicon foam having a hollow portion at the center, a heat insulating member surrounding the outer periphery of the silicon foam, and a Teflon sheet covering the entire surface of the heat insulating member. A casting apparatus for forming a thin film made of resin, wherein a gap between an upper surface of the suction chamber and a lower surface of the die is closed by contact of the seal member body with the die.