JPH084275Y2 - Film fixing device - Google Patents

Description

[Detailed description of the device]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film fixing device used for producing a plastic film by T-die extrusion.

[0002]

2. Description of the Related Art Conventionally, a so-called T-die film forming method has been known in which a molten thermoplastic resin is extruded from a T-die and is brought into contact with a cooling roll to be solidified. Gas suction which has a wide slit extending in the length direction of the T-die surface on the back side of the molten film extruded from the T-die in order to stabilize the fixing to the cooling roll, stabilize the quality and achieve high-speed film formation. A means is provided to suck the gas caught between the molten film and the cooling roll to improve the adhesion of the film to the cooling roll (for example,
(See Japanese Patent Publication Nos. 40-17907 and 41-13626 and JP-A-2-52721).

[0003]

[Problems to be Solved by the Invention] In the above conventional method,
When producing a wide flexible film, if the suction force of the gas is non-uniform in the surface length direction, there will be a difference in the fixing of the film, the quality will not be stable due to the difference in cooling speed, and the temperature difference of the film will also occur. Making high-speed film formation difficult. If the fixing of the film to the cooling roll is not uniform, not only the optical characteristics of the film and various characteristics such as thickness and strength may vary, but also the film is easily corrugated due to the difference in cooling speed. It wraps around rolls, which hinders stable production and higher speed.

Therefore, as in Japanese Patent Publication No. 40-17907, there is a method in which the suction chamber is adjusted by a wall and the partition pressure is adjusted by a valve.
However, this method has a complicated structure for incorporating the valve inside, and is a large-scale device for a wide film, which is not practical.

The present invention improves the quality of the product by preventing the inconvenience that occurs when the wide film in the molten state is fixed to the cooling roll, and enables high-speed film formation.
It is an object of the present invention to provide a fixing device for a die extruded film.

[0006]

In order to achieve the above object, the present invention provides a T-die film forming apparatus provided with a cooling roll and a gas suction port, in which the gas suction port is extruded from the T-die.
Provided on the back side of the film, and a book of the gas suction port
The body is configured to have a plurality of suction pipes with pressure regulating valves in the T-die surface length direction.

The thermoplastic resin used in the present invention includes, for example, polyvinyl chloride, polyvinyl chloride copolymer, polyethylene , polypropylene, polyethylene terephthalate or polycarbonate.

This will be described below with reference to FIGS. 1 and 2. 1 is an explanatory view of a film manufacturing apparatus by T die extrusion, and FIG. 2 is a schematic plan view of piping of a film fixing apparatus according to the present invention attached to the apparatus of FIG.

FIG. 1: A resin melted by an extruder (not shown) is extruded in a film form by a T-die 1 and introduced onto a cooling roll 2 provided close to the film. At this time, the film 3 is fixed to the cooling roll 2 by the melted film extruded from the T die 1.
It is controlled by the negative pressure generated in the suction port 4 provided on the back side . A felt 5 is provided between the cooling roll 2 and the suction port 4 so as to be in contact with the cooling roll 2, and a silicone rubber 6 is used between the T-die 1 and the suction port 4 to close a gap to block invasion of outside air. Then, the suction ability is improved.

FIG. 2: The suction port 4 is connected to a suction blower (not shown) by a plurality of pipes 8. The number of pipes is determined by the surface length of the suction port 4 and the degree of demand for equalizing the suction force. A negative pressure generated from the suction port 4 can be easily equalized in the surface length direction by providing the adjusting valve 7 on each pipe and adjusting the pressure of each pipe 8.

By providing a plurality of pipes with an adjusting valve at the gas suction port for the T-die surface length, the suction control range per unit is narrowed and a fine measure can be taken. For example, if a cooling shortage occurs partially during manufacturing, open the adjusting valve of some piping to increase the suction force and partially revise the pressure bonding of the film to the cooling roll to stabilize the manufacturing. . For a wide film, it is effective to determine the minimum required control range and then increase the number of pipes.

[0012]

EXAMPLE As 100 parts by weight of polyvinyl chloride resin, 40 parts by weight of adipic acid ester such as diisononyl adipate as a plasticizer, 10 parts by weight of epoxidized soybean oil,
As the heat stabilizer, a mixture of 1 part by weight of a calcium-zinc composite stabilizer and 2 parts by weight of an antifogging agent was melted at 200 ° C., and 300 kg / hr was applied from a T die having a face length of 2500 mm.
The sheet is extruded into a sheet with a molten roll, and the molten film is cooled with water having a temperature of 40 ° C. by a negative pressure generated from a gas suction port, and a cooling roll having a diameter of 350 mm rotating at a surface speed of 100 m / min. After being guided to the upper side and cooled and solidified, it was further wound by a winder through several cooling rolls.

Here, the gas suction port is connected to the blower by seven pipes, and a valve for adjusting the pressure is attached to each pipe. By adjusting each valve to make the suction force uniform, the film was stably fixed over the entire width and was able to be continuously operated for a long time. Further, since the gas suction port and the suction blower are connected by a pipe, the gas suction port itself has a simple structure, so that the mounting is easy and the pressure adjustment is easy.

[0014]

[Comparative Example] The number of pipes connecting the gas suction port and the blower is 250 depending on the surface length and the uniformity of suction force.
In a 0 mm T-die, if the number of pipes is three, a large temperature difference occurs due to insufficient fixation of the film on the cooling roll due to variation in suction force in the surface length direction, and the physical properties of the film such as transparency and thickness accuracy are increased. There was a difference. Also,
The film was wavy and difficult to stabilize.

[0015]

The film fixing device having the above-described structure according to the present invention has a simple and compact structure, so that it is inexpensive and easy to install. Since it is connected to the blower by a pipe having a suction force adjusting valve, it is possible to increase or decrease the number of pipes at a relatively low cost depending on the degree of demand for equalizing the surface length and the suction force. Further, in T-die film formation, the film at both ends is thick and difficult to cool, and when the temperature is high and it is easy to wind around the roll, the suction force at both ends is increased and the adhesion to the cooling roll is strengthened, so that stable production is achieved. It is possible. Further, since the valve is provided in the middle of the pipe, a commercially available one can be selected. Further, since there are a plurality of suction ports and each of them is provided with a regulating valve, the suction force can be controlled within a narrower range than before. Furthermore, the adhesion of the molten resin to the cooling roll becomes uniform, the quality is stabilized, and it is also effective for producing a wide film.

Further, in the production of a thin film such as a soft polyvinyl chloride resin containing a large amount of a plasticizer, the apparatus of the present invention enables continuous operation of a wide film with stable quality for a long time. It was

[Brief description of drawings]

FIG. 1 is a cross-sectional explanatory view of a film manufacturing apparatus by T-die extrusion according to the present invention.

FIG. 2 is a piping diagram of a film fixing device attached to the device of FIG.

[Description of sign]

 1 T-die 2 Cooling roll 3 Film 4 Suction port 5 Felt 6 Silicone rubber 7 Adjustment valve 8 Piping

Claims (1)

[Scope of utility model registration request] 1. In a T-die film forming apparatus provided with a cooling roll and a gas suction port, the gas suction port is extruded from the T-die.
A film fixing device provided on the back side of a molten film, wherein the main body of the gas suction port has a plurality of suction pipes with pressure adjusting valves in the T-die surface length direction.