JPH03180317A - Cooling and solidifying device for sheet or film - Google Patents

Abstract

PURPOSE:To make it possible to form high quality resin sheet, both the sides of which are excellent in flatness and lustrousness, by a method wherein both the sides of the sheet are simultaneously cooled by being given, for example, cooling medium over the whole region of the outer peripheral surface of the tightly contacting region of the sheet on a second cooling roll. CONSTITUTION:Resin, which is melted with an extruder, is extruded through a die 1 in sheet form. The molten sheet 2 comes into contact with the surface of a rotating first cooling roll 4. A second cooling roll 5 is arranged below the first cooling roll 4 by the predetermined interval. Some part of the second cooling roll 2 is immersed in the cooling water in a cooling tank 10. In a zone ranging from a nip point (c) to the starting point (d) of the immersion in the cooling water in the cooling tank 10, liquid spray generators 11 are provided so as to spray cooling liquid over the whole surface of the sheet on its side opposite to the second cooling roll. In order to prevent the surface of the sheet on its side opposite to the second cooling roll 5 from being re-melted by the heat flow fed from the interior of the sheet in said zone, cooling liquid is sprayed from the liquid spray generators 11 over the surface of the sheet on its side opposite to the second cooling roll for forced cooling, resulting in cooling the sheet effectively.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to molded sheets and films (hereinafter referred to as sheets) that are applied to thermoplastic resin sheet and film manufacturing equipment, raw fabric forming equipment of biaxial stretching machines, etc. This relates to the cooling and solidification equipment of .).

(Prior Art) FIGS. 3 and 4 show an example of a cooling and solidifying device used in a conventional thermoplastic resin sheet manufacturing process. FIG. 3 shows an example in which two or more cooling rolls are used, and FIG. 4 shows an example in which one cooling roll is used.

In FIG. 3, a resin melted by an extruder (not shown) is extruded into a sheet form from a die 1 and comes into contact with the surface of a rotating first cooling roll 4.

At this time, air is blown by the air knife 3 to the surface of the molten sheet 2 opposite to the contact surface of the roll 4 near the contact point, and the air that is about to be caught between the molten sheet 2 and the first cooling roll 4 is is excluded. The molten resin sheet 2 in close contact with the first cooling roll 4 is sequentially passed through the following second cooling roll 5 and third cooling roll 6 to be solidified, and then transferred to the next process via the nip roll 8.

In FIG. 4, a resin melted by an extruder (not shown) is extruded from a die 1 into a sheet, and the molten sheet 2 contacts the surface of a rotating cooling roll 4. At this time, air is blown by the air knife 3 to the surface of the melting sheet 2 on the opposite side of the contact surface of the roll 4 near the contact point, and air that is about to be caught between the melting sheet 2 and the cooling roll 4 is removed. be done. Here, a part of the lower part of the cooling roll 4 is immersed in a cooling water tank 10, and therefore, the molten sheet 2 is passed through the cooling water while traveling along with the cooling roll 4, thereby improving the cooling ability of the surface on the opposite side of the roll. After the resin sheet is rapidly cooled and solidified, it is transferred to the next step via nip rolls 8.

(Problem B to be solved by the invention) In the sheet forming method using multiple rolls shown in Fig. 3, since both sides of the sheet are in close contact with the rolls in a molten state, flatness and
It is possible to form sheets with excellent gloss. However, with this forming method, when forming at high speed or under forming conditions where the sheet thickness is thick, the cooling capacity of the sheet surface on the opposite roll side when passing through the second and third cooling rolls is insufficient, and the sheet There is a problem with remelting.

On the other hand, when the sheet is continuously immersed in a cooling water tank as shown in Fig. 4, the surface of the sheet on the opposite roll side is flat and glossy compared to the formability using multiple rolls as shown in Fig. 3. It will be extremely inferior.

The present invention has been made to solve these problems,
The object of the present invention is to provide a sheet cooling/solidifying device that has excellent flatness and gloss on both sides of the sheet and is capable of rapid cooling at the same time.

(Means for Solving the Problems) For this reason, the present invention provides that the surface of a sheet-like or film-like thermoplastic molten resin sheet extruded from a die is alternately passed between cooling rolls provided in a plurality of rows perpendicular to the feeding direction. In a thermoplastic resin sheet molding device that cools and solidifies by contact, at least two cooling rolls are used to alternately bring the molten sheet surface into close contact with the rolls to maintain flatness and gloss on both surfaces of the sheet. , immediately after the sheet is transferred to the second cooling roll, e.g. a liquid spray generator,
The sheet surface on the opposite roll side is cooled using a liquid jet generator, a gas jet generator, etc., and the surface portion is continuously immersed in cooling water without remelting, or, for example, the liquid spray generator described above is used. A large number of cooling liquids are arranged along the length of the sheet along the cooling roll, and a cooling liquid is injected over the entire surface of the sheet on the side opposite to the roll, so that the sheet is rapidly cooled in the second cooling roll section. is the solution to the above problem.

(Function) The molten resin sheet extruded from the die advances while its surface is brought into close contact with the surface of the first rotating cooling roll, and then the sheet surface on the opposite side is brought into close contact with the second cooling roll. Like being guided through a nimp point.

When the sheet is guided to the second cooling roll, a cooling medium is applied to the surface of the sheet opposite to the roll from a cooling medium application means such as a cooling water jetting device, which is disposed over the entire outer peripheral surface of the sheet contact area of the second cooling roll. applied and cools both sides of the sheet simultaneously.

As a result, remelting of the sheet surface is eliminated, and smoothness and gloss on both sides of the sheet due to roll contact are ensured.

(Example) Hereinafter, the present invention will be explained in detail based on illustrated embodiments.

FIG. 1 shows a first embodiment of the present invention.

In the figure, resin melted by an extruder (not shown) is extruded into a sheet from a die 1, and the molten sheet 2 contacts the surface of a rotating first cooling roll 4. At this time, air is blown by the air knife 3 to the surface of the molten sheet 2 opposite to the contact surface of the roll 4 near the contact point, and the air that is about to be caught between the molten sheet 2 and the first cooling roll 4 is is excluded.

A second cooling roll 5 is installed below the first cooling roll 4 at a predetermined interval, and a portion of the second cooling roll 5 is immersed in cooling water in a cooling water tank IO. The sheet 2, which is fed as the roll rotates while contacting the surface of the first cooling roll 4, is nipped at point C by the second cooling roll 5, and thereafter is nipped at point C while contacting the surface of the second cooling roll 5. It is transferred within the cooling water tank 10 as the roll 5 rotates.

In this case, the surface temperature of the opposite-roll side of the sheet 2 in contact with the first cooling roll 4 up to the nip point C is kept above the solidification temperature, and the sheet 2 is brought into close contact with the roll surface of the second cooling roll 5 in a molten state. ing.

Further, the roll side surface temperature of the sheet 2 in contact with the first cooling roll 4 is cooled to below the solidification temperature before reaching the nip point C in order to maintain the flatness and gloss of the sheet 2.

In the section from the nip point C to the starting point d where the sheet 20 is immersed in the cooling water of the cooling water tank 10, a liquid spray generator 11 is disposed so that the cooling liquid is sprayed over the entire surface of the sheet 20 on the opposite roll side. In order to prevent remelting of the sheet surface on the opposite roll side of the second cooling roll 5 due to heat flow from inside the sheet, cooling liquid is injected from the liquid spray generator 11 to the sheet surface on the opposite roll side to perform forced cooling, thereby effectively Cool the sheet.

After passing the immersion start point d, the sheet 2 is placed in the cooling water tank 10.
It is cooled and solidified in the process of being continuously immersed in cooling water, and is transferred to the next process via nip rolls 8. here,
In place of the liquid spray generator 11 shown in FIG. 1, it is also possible to provide a liquid jet generator or a gas jet generator to prevent remelting on the sheet surface on the opposite roll side of the second cooling roll 5. .

FIG. 2 shows a second embodiment of the invention. In the above embodiment shown in FIG. 1, the sheet 2 was rapidly cooled using the cooling water tank 10, but in this embodiment, as shown in FIG. By arranging the liquid spray generators 11 over the entire area, it is possible to ensure a heat transfer coefficient comparable to that of the first embodiment.

(Effects of the Invention) As described above in detail, the cooling and cooling of the sheet according to the present invention
The solidification device not only enables rapid cooling of the thermoplastic molten resin sheet, but also enables the bottom shape of a high-quality resin sheet with excellent flatness and gloss on both sides of the sheet.

[Brief explanation of drawings]

FIG. 1 is a sectional view schematically showing a sheet cooling/solidifying apparatus according to a first embodiment of the present invention, and FIG. 2 is a sectional view schematically showing a sheet cooling/solidifying apparatus according to a second embodiment. 3 and 4 are cross-sectional views schematically showing different conventional sheet cooling and solidifying devices. Explanation of main parts of the diagram 1 - Die 2 - Sheet 4 - First cooling roll Second cooling roll 10 - Cooling water tank 11 - Liquid spray generator Fig. 1 Fig. 2 Fig. 3 Fig. 4

Claims (1)

[Claims] A thermoplastic resin sheet or film that is cooled and solidified by bringing the surface of a sheet-like or film-like molten resin extruded from a die into contact with two or more rotating cooling rolls installed perpendicular to the feeding direction. A sheet or film cooling/solidifying device characterized in that a cooling medium application means for cooling the surface of the sheet or film on the opposite roll side that is in close contact with the cooling roll is provided around at least the second cooling roll.