JP2002036333A - Film and sheet molding method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film and sheet molding method by which a sheet having satisfactory surface smoothness and high transparency and brightness and the like, especially a thin sheet of 0.2 mm or less thickness can be molded. SOLUTION: This film and sheet molding method using a plurality of arranged rolls comprises the following steps of making molten plastics discharged from a T-die flow through a space part formed between a main cooling roll and an outer cylinder as well as an inner cylinder in the same manner as is a cooling medium such as water or oil and further, guiding the same into a nip between touch rolls formed in such a fashion that the radial thickness of the outer cylinder is larger than that of the inner cylinder by about 1/2-1/10, and molding the molten plastics into a sheet passing through an auxiliary cooling roll and an annealing roll.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method in which molten plastic discharged from a T-die or the like is passed through a roll gap between a main cooling roll and a touch roll and then passed through a sub-cooling roll or thereafter through an annealing roll.
The present invention relates to a film having a plurality of rolls, such as rolls of three or four rolls, and a sheet forming method.

[0002]

2. Description of the Related Art Conventionally, this type of film / sheet (hereinafter simply referred to as "sheet") forming method will be described with reference to FIGS. 6 to 9. As shown in FIG. With a predetermined pressing force (10 to 30 kgf / cm), the main cooling roll 4 is pressed with a relatively large pressing force for a thin material and a small pressing force for a thick material. After passing through the roll gap δ, the annealing roll 5
Through the sheet 6 and sent to a winding device (not shown).

As shown in FIGS. 7 and 8, the main cooling roll 4, the annealing roll 5, and the touch roll 3 are reinforced by a thick outer tube 7 and a thinner inner tube reinforcing plate 8 for rigidity. A first shaft 12 and a second shaft 13 having through-holes 10 and 11 at the center, respectively, which rotatably support the outer cylinder 7 and the inner cylinder 9 at both ends in the width direction of the inner cylinder 9.
The cooling medium such as water or oil is supplied with a through-hole 10 as shown by an arrow a, a space 14 formed between the inner diameter of the outer cylinder 7 and the outer diameter of the inner cylinder 9, and the through-hole 11. The cooling roll which guides in the order of is comprised.

[0004]

However, as shown in FIG. 9, in the case of a sheet 6 that has passed through the roll gap δ, particularly in the case of a thin sheet having a thickness of 0.2 mm or less, the mirror surface (transparent sheet) of the roll surface of the touch roll 3 In the case of molding, the transfer of the matte surface (in the case of opaque sheet molding) cannot be performed, and the local portion that could not contact the roll surface has irregularities 15 or dust wrinkles, cloudiness, pock, etc. on the sheet surface, It appeared as a so-called touch omission phenomenon, and a good product could not be formed.

In general, a thin sheet having a thickness of 0.2 mm or less is formed by blowing cooling air onto a cooling roll from an outer side surface with an air knife or the like.
In this method, since the sheet surface on the air knife side does not contact the roll surface, the surface smoothness, transparency, gloss, and the like are poor, and as a result, a thin sheet having a thickness of 0.2 mm or less cannot be formed.

This is because the thickness of the outer cylinder is increased in order to provide rigidity to the touch roll, and the roll itself is not flexible, and the time required for the width in the width direction of the molten plastic originally supplied from the T-die is reduced. Due to lack of uniformity, the roll surface did not conform to the thin sheet surface, resulting in impaired transferability.

[0007] An object of the present invention is to provide the above-mentioned touch roll which is inflexible, the roll surface does not conform to the sheet surface, and therefore has no transferability on the roll surface, and particularly has a surface smoothness and transparency of 0.2 mm or less in thickness. Eliminating the drawback that thin sheets with good gloss were not formed, the touch roll fits well into the sheet surface, and forms a sheet of uniform thickness with good surface smoothness, transparency and gloss, etc. It is an object of the present invention to provide a sheet forming method capable of forming a sheet.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention relates to a method in which molten plastic discharged from a T-die is supplied to a space formed between a main cooling roll, an inner cylinder, and an outer cylinder with water or oil. While allowing the cooling medium to flow, the thickness of the outer cylinder is guided between the touch rolls having a thickness of about 1/2 to 1/10 that of the inner cylinder, and then the film / sheet is passed through the sub-cooling roll. A thin film / sheet forming method with a plurality of rolls to be formed was adopted.

The sub-cooling roll is configured to allow a cooling medium such as water or oil to flow through a space formed between the inner cylinder and the outer cylinder having the same structure as the above-mentioned touch roll, and to reduce the thickness of the outer cylinder. It is preferable that the thickness is about 1/2 to 1/10 of that of the inner cylinder.

According to the present invention, the touch roll is well adapted to the sheet at the roll gap δ, and the transfer property of the roll surface is good. As a result, a sheet having good surface smoothness, transparency and gloss can be formed. It is also possible to form a thin sheet having a thickness of 0.2 mm or less.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 1 to 4 by taking as an example a method of forming a relatively thick sheet having smoothness, transparency and gloss on the front and back surfaces of the sheet. I do. At the time of explanation, the present invention adds a touch roll and a sub-cooling roll of the conventional method,
The same members as those in the related art are denoted by the same reference numerals, and the description thereof will be omitted, and only newly added members will be described with the new numbers.

The molten plastic 2 discharged from the T-die 1 is pressed against the main cooling roll 4 by a predetermined pressing force (100 to 100).
The roll gap δ between the touch roll 20 and the main cooling roll 4 pressed at 300 N / cm) is set to the first bank 21.
After forming the second bank 23, the roll gap between the main cooling roll 4 and the sub cooling roll 22 is
Is formed, passes through an annealing roll 5 and becomes a sheet 24 to be sent to a post-processing device (not shown).

As shown in FIG. 2, the touch roll 20 has an inner cylinder reinforcing plate 25 and an inner cylinder 26 having rigidity with a thickness T, and about 1/2 to 1/10 of the thickness T of the inner cylinder 26. Outer cylinder 2 with thick wall
7 and a first shaft 32 and a second shaft 33 having through holes 30 and 31 provided at the center rotatably supported by bearings 28 and 29 at both ends in the width direction, respectively.
A cooling medium such as water or oil is passed through the through hole 30, the space 34 formed between the inner cylinder 26 and the outer cylinder 27, and then the through hole 31 as shown by the arrow b.

As shown in FIG. 4, the roll surface C of the roll 20 is provided with a crowning such that the sheet is linearly flexible in the width direction by the pressing force of the roll 20 against the main cooling roll 4. The amount is calculated by the pressing force,
If the maximum diameter D and the minimum diameter d are (D−d), the roll surface C is smoothly connected with a predetermined radius R.

The embodiment described above is an example in which four vertical rolls are combined. As shown in FIG. 5, as shown in FIG. The combination of the four rolls of the cooling roll 22 and the annealing roll 5 may be a horizontal type, and the sub-cooling roll 22 may be a roll 36 whose outer cylinder having the same configuration as the touch roll 32 of the present invention is thinner than the inner cylinder. good. Furthermore, not only by the combination of four rolls,
The present invention is also effective for forming a thin sheet to a thick sheet using a plurality of rolls.

As described above, since the touch roll has a thin outer cylinder and is easy to bend, the touch roll surface is melted even if the molten plastic supplied from the T die is thin at the roll gap δ. The roll was well adapted to plastic, and the transferability of the roll was improved. As a result of a molding test, a thin sheet having a good surface could be molded.
Next, the molding data of the molding test will be described. Raw material: PET (intrinsic viscosity 0.8) Extrusion amount: 100 kg / h Molding speed: 15 m / min Sheet thickness: 100 μm (0.1 mm) Sheet width: 760 mm Touch roll pressing linear pressure: 164 N / cm Touch-out phenomenon: None Sheet Thickness accuracy: ± 6% Sheet surface: good

[0017]

According to the present invention, the molten plastic discharged from the T-die, which has been initially listed, is passed between a plurality of rolls so that the sheet surface is smooth, and the sheet has good transparency and gloss. In particular, the drawback that a thin sheet with a thickness of 0.2 mm or less could not be formed has been removed, and in the roll gap, the touch roll has become familiar with the sheet surface, and it has become possible to form a glossy sheet having a good surface. .

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a sheet forming method according to an embodiment of the present invention.

FIG. 2 is an explanatory view of a touch roll used in a sheet forming method according to an embodiment of the present invention, and is a sectional view in the axial direction.

FIG. 3 is an explanatory view of a touch roll used in a sheet forming method according to an embodiment of the present invention, and is a cross-sectional view along AA in FIG. 2;

FIG. 4 is an explanatory diagram of a touch roll used in a sheet forming method according to an embodiment of the present invention, and is a diagram illustrating an outer shape thereof.

FIG. 5 is an explanatory view showing a sheet forming method according to another embodiment of the present invention, and is an explanatory view when a roll is used in a lateral direction.

FIG. 6 is an explanatory view showing a conventional sheet forming method.

FIG. 7 is an explanatory view of a touch roll used in a conventional sheet forming method, and is a sectional view in the axial direction.

FIG. 8 is an explanatory view of a touch roll used in a conventional sheet forming method, and is a cross-sectional view taken along the line BB of FIG. 7;

FIG. 9 is a view as viewed in the direction of the arrow in FIG. 6, and is an explanatory diagram showing a relationship between a touch-out phenomenon and a sheet surface.

[Explanation of symbols]

 Reference Signs List 1 T die 2 molten plastic 4 main cooling roll 5 annealing roll 20, 32 touch roll 21 first bank 22, 36 sub cooling roll 23 second bank 24 sheet 25 inner cylinder reinforcing plate 26 inner cylinder 27 outer cylinder 28, 29 Bearings 30, 31 Through holes 32 First shaft 33 Second shaft 34 Space

Claims (2)

[Claims] 1. A molten plastic discharged from a T-die is made to flow a cooling medium such as water or oil into a space formed between a main cooling roll and an inner cylinder and an outer cylinder. Is formed between a plurality of touch rolls having a thickness of about 1/2 to 1/10 of that of the inner cylinder, and then formed into a film and a sheet through a sub-cooling roll. 2. The sub-cooling roll allows a cooling medium such as water or oil to flow through a space formed between the inner cylinder and the outer cylinder, and the thickness of the outer cylinder is set to be smaller than that of the inner cylinder by one. 2. The film and sheet forming method according to claim 1, wherein the thickness is about 1/2 to 1/10.