JPS62218121A - Method of extruding resin film and device thereof - Google Patents

Abstract

PURPOSE:To suppress the neck-in and consequently to improve the product quality and production efficiency by a method wherein the side edges of a film are extended by means of local rotary flowing action and film sticking action. CONSTITUTION:Deckel holders 2, each of which contains an exterior type deckel 2a, are fixed at the tip parts of the lip 1a of a die 1. A rotary deckel 4 is arranged at the tip of the deckel holder 2 in such a manner that the peripheral surface contacts with the side edge of a resin film A. The diameter (d) and width (w) of the rotary deckel, the distance (l) between the center of the rotary deckel and the die lip and the like are determined on the basis of the molecular weight and viscoelasticity of resin, the resin output through the extruder die, an air gap, processing speed and the like. The side edges of the resin film A extruded through the die is, at first, extended by the exterior type deckel 2a and then extended again by the rotary flowing action produced between the film and the rotary deckel. Thus, the resin film A is extended in the state that the side ends of the extruded resin film are locally flowed rotarily in the width direction of the resin film. Consequently, the neck-in of the resin film A is suppressed.

Description

[Detailed description of the invention] [Industrial application field] In the present invention, thermoplastic resin is extruded from an extrusion die.

The present invention relates to extrusion molding technology for processing films, sheets, flat plates, etc. using cooling rolls, etc., and more specifically relates to technology for preventing the so-called neck-in phenomenon of extruded resin films.

[Prior Art] When the product width changes during extrusion coating, the die width can be adjusted and operation can be continued. At this time, the die width is set to 21
A die width adjustment device or die-width adjustment device is used for this purpose. There are internal and external types of Ditkel, and the internal type was previously used because of its simple structure and ease of changing the width during operation, but it was prone to resin leakage and the edges of the discharged film were unstable. External type Dickels have come to be used because they tend to cause problems (for example, Japanese Patent Application Laid-Open No. 1988-124 (ILA)).Furthermore, external type Dickels and internal type Dickels have also been used together. ing.

[While the invention is trying to solve', XJ] However,
At present, when conventional discels are used, the neck-in phenomenon cannot be sufficiently prevented. Therefore, various problems caused by the neck-in phenomenon occur. Namely.

(a) Parts with relatively different thicknesses are formed at both ends (edges) of the resin film, resulting in increased non-uniformity in the thickness of the extruded film (or extruded coating film).

(b) Due to this uneven thickness, when winding a long length into a roll, the winding becomes abnormally thick at both ends of the two-winding roll, resulting in misalignment of the first winding, elongation of the edge, etc. Defects such as making it difficult to remove are likely to occur.

(C) Because of this non-uniformity in thickness, it is common practice to cut (slit) the abnormally thick portions at both ends and then wind them up into a roll, but the cut portions do not become products and are discarded. This results in material loss and is extremely uneconomical.

In addition, the abnormally thick portions at both ends of the resin film have a large heat capacity.

Since the temperature decreases until it reaches the nip roll is small and fluidity is preserved, it becomes resistant to adhesion to the nip roll and is easily wound around, making it difficult to continue processing and even causing a situation where continuous operation is interrupted.

Against this technical background, the purpose of the present invention is to suppress the neck-in phenomenon as much as possible, and to solve various problems (a) (b) caused by this phenomenon.
) The objective is to eliminate (e) and thereby improve product quality and production efficiency.

[Means for Solving Problems According to the Invention] The present invention first provides a method for extrusion molding a resin film by locally rotating and flowing the side end portions of the extruded resin film in the width direction of the resin film.

Second, the present invention provides a resin film extrusion molding apparatus that is equipped with a rotating deckle near the resin film extrusion position.

In the present invention, although the detailed mechanism for eliminating neck-in is unknown, the side edges of the resin film are expanded upon contact with the 9-rotating body and restore their original shape when separated from the 1-rotating body, and through this action, the side edges of the resin film are It is thought that the neck-in problem will be resolved. Considering from the perspective of the pressure exerted on the membrane, the pressure from the rotating body increases from the start of contact between the rotating bodies until the center of the contact rotation path, and then decreases until it leaves the rotating body.
External pressure becomes zero due to Is release. Approximately corresponding to this, internal stress is generated (increases and decreases) at the side edges of the membrane.

The method of the present invention is characterized in that the membrane side edges are expanded by a local rotational flow effect and a membrane viscosity effect, and is essentially different from the conventional method in which the membrane lateral edge is expanded only by a membrane adhesive effect. However, this rotational flow action includes both a case where the side edge of the resin film immediately starts to expand, and a case where the side edge of the resin film once contracts and then shifts to expansion. In the former case, the two-turn Dickskel is placed so that its side surface is in contact with the surface of the resin film, and the rotational flow effect of the side surface of the one-turn Dickskel is utilized.In the latter case, the one-turn Dickskel is placed so that its peripheral surface It is placed in contact with the side edge of the resin film, and utilizes the rotational flow effect of the circumferential surface of the one-turn Dickel.

The rotating discs are preferably arranged on both sides of the resin film. The contact surface of the rotary disc is preferably a uniform cylindrical outer peripheral surface, but it may also be a curved surface or a part of a spherical surface. When the side surface of the rotary disc is used as a contact surface, it is preferable that the contact surface is a disc-shaped or conical surface. The rotating Dickel is rotated by the driving force or the extrusion force of the resin film. The rotation speed is controlled by a predetermined rotation adjustment mechanism. It is preferable that the peripheral speed of the rotating Dickel is approximately equal to the extrusion speed of the 6 parts in the membrane. The rotary disk is disposed close to the die extrusion port or at a predetermined distance away (a position where it can effectively receive the rotary flow action). Further, the one-rotation disk may be partially or entirely located inside the die. In relation to the side edge of the resin film, it is necessary that the outer circumferential surface of the one-turn Ditzkel comes into contact with at least the side edge of the resin film, and in order to effectively exert the two effects, it is necessary to position it at a position where approximately half the circumferential surface or more is in contact. preferable.

Several rotating Dickels may be arranged on one side edge of the resin film. The rotary diskel is generally made of the same metal material used for dies and the like (eg, mechanical structural steel), but other materials may be used as long as they have low adhesion to the membrane. The temperature of the rotating deckle does not require particular control in the case of a metal deckle, but it can be kept warm or heated if necessary.

The rotating Dickel of the present invention is different from the conventional fixed Dickel (
Although it can be used in place of the internal type or external type, it is also preferable to use it in combination with a fixed type. When used in combination, it is preferred that the membrane exerts the action of a rotating deckle after it has left the fixed deckle.

[Embodiment] Figures 1 and 2 show the first embodiment,
In each figure, 1 is a die, and A is a resin film extruded from the die. A Ditzkel holder 2 containing an external Ditzkel 2a is fixed to the tip of the lip 1a of the die 1 with a bolt 3, so that the side edge of the resin film A and the tip of the Ditzkel holder 2 face each other. There is. A rotary deckle 4 rotated by a drive motor (not shown) fixedly supported by the deckle holder 2 is provided at the tip of the deckle holder 2. The side edges of the base are in contact with each other. Reference numeral 5 denotes a protrusion extending from the deckle holder 2 and serving as a means for promoting separation of the resin film from the deckle 4 during one rotation, and the state of expansion can be adjusted by the position of this tip.

Here, d is the diameter of the rotating Dickels.

31-40III11. Yori better <ha 5~20mf
It is preferable to set it in a range of about f1. The key is to select the coating width as close as possible to the resin extrusion width, that is, the die width. Therefore, the width of the resin film may become wider than the width of the discharge port of the die due to expansion by one rotation of the disk. W is the width of the rotating Dietkel, 0.5 ~
5IIIm, ,,t: Favorite L<Ha l"~3"fW
It is preferable to set it within the range of If. The outer peripheral surface shape of the rotary disk may be flat or curved along the width direction. Diameter d and width W1 of rotating Dietkel
The distance between the rotating Ditzkel center and the grip, etc. is actually the molecular mouth of the resin.

It is preferable to determine it experimentally depending on the viscoelasticity, the amount of resin extruded through the die, the air gap processing speed, etc. Regarding the circumferential speed V of the rotating Dickel, it is preferable that the speed be approximately the same as the resin flowing down and stretching speed (processing speed ■) (for example, ±l
Slightly slower or faster speeds within 0% are acceptable)
.

Regarding the relationship between the width W of the rotating Dickel and the die gap t, in order to ensure expansion.

It is better to set w>t. The distance #I depends on the diameter of the one-rotation deckle, but in the case of using the externally fixed deckle shown in Fig. 1, it is preferable to keep the resin film within a range that does not separate from the fixed deckle 2, and the resin used Although it varies depending on the operating conditions, generally J-40 to GO City is adopted.

According to such a die device, the side edge of the resin film A extruded from the die is first expanded by the external fixed deckle 2a, and then expanded by +1f degree by the rotational flow action with the rotating deckle. This suppresses the neck-in phenomenon regarding the resin film A as much as possible.

FIG. 3 shows a second embodiment, in which the same components as those of the previous embodiment are given the same reference numerals, and the explanation thereof will be omitted. In this case, one revolution is 4 dekels.

The upper end thereof is arranged to correspond to the lower end of the die lip 1a,
The resin film A extruded from the die 1 is subjected to the spreading action by the rotating disk 4 immediately after extrusion. In a case like this embodiment, the distance between the tip of the grip 1a and the rotational Dickels center is (-, where d is the Dickels diameter of one rotation, d/2≦β', and generally (-15 to 5
It should be approximately 0 mm.

[Example] In the film processing apparatus shown in FIG. 4, actual extrusion molding was carried out using the resin width adjusting device shown in FIG. 6 is a motor that drives the rotary disc; 7 is a cooling drum; 8
9 is a nip roll, and 9 is a peeling roll. In this example, one rotation of Dickel 4 is d: 12mm, w;
2mm, located at p 4o mff1, low density PE resin discharged at 300°C1 i7t48kg/br,
It was processed into a film with an average thickness of 20 μm in 7 minutes at a die width of 400”, an air gap of 12011°, and a processing speed of 100 m for 7 minutes. The circumferential speed of the one-rotation Dickel 4 was set at 96 m/min. The results are shown in the table.

As a comparative example, a device with an externally fixed Dickel was used (
Figure 5) shows a film processed under the same conditions.

As is clear from the above table, according to the examples, neck-in was reduced compared to the comparative examples, and the non-uniformity of the resin film thickness at both ends could be significantly improved. In addition, when the processed film was wound up into a roll, in the case of the example, it was possible to roll up to 2000 inches, but in the case of the comparative example, both edges of the roll became convex when wound up to 500 inches, resulting in a shift of one roll. In addition, in FIGS. 3 and 5, the neck-in width on one side is indicated by Nl.

[Effects of the Invention] According to the present invention, the neck-in phenomenon can be reduced and the above-mentioned objects can be achieved, so that the present invention is extremely important in the field of extrusion technology.

[Brief explanation of drawings]

FIG. 1 is a schematic front view showing a first embodiment of the present invention. FIG. 2 is a sectional view taken along the line ■-■ in FIG. FIG. 3 is a schematic front view showing another embodiment of the present invention. FIG. 4 is a schematic diagram of a film processing apparatus equipped with the apparatus of the present invention, and FIG. 5 is a schematic front view of a conventional example (equipped with an external deckle). 1... Extrusion die 4... Rotating Dietkel A... Resin film

Claims (2)

[Claims] (1) A method for extruding a resin film, in which the side ends of the extruded resin film are locally rotated and flowed in the width direction of the resin film. (2) A resin film extrusion molding device comprising a rotating deckle near the resin film extrusion position.