JPS5857924A - Air ring for cooling bubble in inflation type film forming device - Google Patents

Abstract

PURPOSE:To form excellently transparent film which is appropriately adjustable in inner diameter regardless of change of film diameter and inflation ratio by installing a device capable of changing an inner diameter in an upper air ring of the air rings equipped at two stages, upper and lower. CONSTITUTION:A ring device A comprises a stop mechanism made of blades 12 which are equipped between a ringed holder 10 of an upper air ring 4 and a ringed rotary plate 11 with the same inner diameter as the holder 10 and move to or from the center by the turning operation of the rotary plate 11. In the stop mechanism, a suitable number of arch blades 12 are combined and arranged in the circumferential direction and in piles between the ringed holder 10 and the rotary plate 11. One end of the arch blade is pivoted rotatively about a spindle 13 on the holder 10 and a spindle 14 pivoted to the other end thereof is fitted slidably and loosely to the guide grooves 16 on the rotary plate 11. Therefore, when the rotary plate 11 is revolved in any direction the spindles 14 slide in the guide grooves and the blades 12 turn above the spindles to change the inner diameter D.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an air link used for cooling a bath melt bubble formed by extruding a tubular I from a die during film forming by the inflation and scoring method.

The transparency of the film obtained by the inflation method depends on the degree of cooling of the bubble. However, if the air link Jjt7 is increased and the bubble is rapidly cooled, a film with good transparency can be obtained, but the melt tension tJz';5
For example, medium-low pressure method, polyethylene or ethylene-a-
For olefin copolymers, etc., when the air volume is increased, the vibration of the bubbles increases, making it more likely to wrinkle, making it difficult to maintain a high quality product.

During this time, in order to deal with Mjζ, air links are provided in two stages, upper and lower, and the bubble is preliminarily cooled in the first air ring, and then cooled and solidified in the second air ring. I proposed 3-7 ¥≦764 by issue.

In order to enhance the cooling effect of the bubble and obtain a film with good transparency, it is also necessary to reduce the gap between the lip of the air ring and the tubular film.
In the case where the air ring is provided in two stages, upper and lower, as shown in No. 74, transparency can be improved if the gap between the upper air ring glue 9 and the tubular film is within a small and appropriate range. It was discovered that a good film could be obtained.

However, with this air ring, if the size of the tubular film is changed by changing the die, or the expansion ratio is changed and the gap between the tubular film and the tubular film increases beyond the appropriate range, the cooling effect will be impaired, Even if the film was provided in stages, a film with good transparency could not be obtained, and the bubbles swayed violently, making the molding unstable. Therefore, when the size of the tubular film changes or the swelling ratio changes, the moldability will not be affected.
In order to obtain a good film for the gate pillar, it would have been necessary to replace it with an air ring with a lip diameter that matched the film, but this would have required a considerable amount of time and effort, and the loss caused by this would have increased the equipment size. It tended to get bigger. Moreover, the molding machine was stopped while the air ring was replaced, resulting in a decrease in production and loss of raw materials.

In order to solve the above problem, the present invention installs a device that can easily change the inner diameter in the upper air ring of the upper and lower air rings provided in upper and lower air rings, so that the size and expansion ratio of the tubular film change due to kneading. This makes it possible to always obtain a film with good transparency without having to replace the air ring.

To explain the stiffness with reference to Figure 1, a thermoplastic resin melt-kneaded with an extruder (not shown) is extruded into a tube shape from a die 1, and the molten bubble 2 formed by expanding with compressed air is first tied. The first air ring 3 provided above the first air ring 3 preferably faces diagonally upward, particularly preferably the first air ring 3 provided above the first air ring 3.
Preliminary cooling is performed with cooling air blown out at an angle of 0, and then the second air ring 4 provided above the first air ring is directed upwardly or diagonally upward, preferably 4t! In an inflation film forming apparatus in which the air ring is cooled and solidified by cooling air blown out at an angle of 0, the film is folded by a stabilizer plate 5, and then wound around a pinch roll 6. It is equipped with a ring device that can be easily changed.

By adjusting the inner diameter according to the diameter of the bubble, the ring device A can not only improve the cooling effect but also contribute to the stabilization of the bubble.

In addition, from the perspective of bubble stabilization, the above ring device is the first
It is more effective if it is also provided on the lower side of the air ring 4 as shown in the figure.

Next, the structure of the ring device fiA will be explained with reference to FIGS.

The ring device is installed between an annular stand 10 attached to the air ring 4, an annular rotary plate 11 having the same inner diameter as the iron stand, and the rotary plate stopper stand, and is capable of rotating the rotary plate 11. It consists of a diaphragm mechanism consisting of blades 12 configured to advance and retreat toward the center. The aperture mechanism also includes a ring-shaped base 10 and a rotating plate 11, with one end rotatably attached to the base by a shaft 13, and a shaft 1 rotatably attached to the other end.
4 is slidably fitted into the guide r416 of the rotary plate, arch-shaped blades 12 are arranged so as to overlap each other in an appropriate number of circumferential directions, and the rotary plate can be rotated in one direction. When operated, the blade #114 slides in the guide groove 16, pivoting the blade, and changing the inner diameter D.

In this case, instead of providing the guide groove 16 on the rotary plate and the shaft on the blade, a shaft may be attached to the rotary plate and the shaft may be loosely fitted into the guide groove formed on the blade. It may be replaced by a slider of known shape that slidably fits into the groove.

In order to simplify the structure and make it easier to understand, the figure shows the number of blades reduced and enlarged.In actual use, the shape of the blades will be closer to the polygon or circle formed by the blades. It is desirable to increase the number of blades and to make the width of the blades relatively small so that the inner diameter becomes large.

According to this ring device, in addition to obtaining the same effects as the above-mentioned ring device, there is also the advantage that the inner diameter can be adjusted steplessly. Figure 6 shows another example of a ring device.The required number of ring plates, each with a different inner diameter, is divided into several parts in the circumferential direction, preferably into two parts, and prepared so that the film diameter or expansion ratio can be changed. Then, each arc-shaped piece of the ring plate that is suitable for this is selected, and the straws are arranged and assembled in an annular shape on the air ring 4. According to this method, the structure of the ring device becomes extremely simple.

7 to 72 show still another embodiment, in which 21 is formed by an upper surface or a horizontal part 211 and an inclined part 21b, and is preferably placed on the air link 4 in a close contact state. A trapezoidal support stand 22 is attached, and when it is piled up on the inclined part 21b of the support stand, each lower end surface 22a is flush with the bottom surface of the support stand 21, and each upper end Or the three funnel-shaped plates located on the extension of the horizontal part 21a are divided into four, and each of the intermediate and lower layer lips, excluding the one-layer slide plate, is an individual slide plate or a slide plate each having a quarter-circular cross section. At the upper end of the board, there are several protrusions 23 at appropriate places except for the center part, which protrude upward. Raised upper station side end surface 221)
When it hits the protrusion 23 of the lower slide plate and is stopped (Fig. 2), the center part of the upper end face 22b of each slide plate is aligned (Fig. 2) and the upper side with a smaller inner diameter. The lower end of the sliding plate is located on both sides or on the same level as the minimum diameter part (lower end) of the lower sliding plate (Fig. 10.11), or on the outer side of the lower sliding plate, and is located on the inside of the lower sliding plate. Make sure it doesn't stick out. In FIG. 9, a recess may be formed in the upper circumferential end surface of the slide plate on the -h side, and the protrusion 23 of the lower slide plate may be fitted into the recess.

Figures r to θ show the state when the inner diameter is at its maximum diameter, and when reducing the inner diameter from this point, the entire slide plate stacked in three layers is first placed on the inclined part 21b of the support base. Slide it down to the bottom 4-).

The slide plates are joined together to form a ring shape.
When the descent is stopped, the lower end surface 22a becomes flush with the bottom surface of the support base, and the first step of diameter reduction is performed.Then, the middle and upper layer blind plates are similarly pushed out, and the middle slide Whether the diameter is reduced in the second stage when the plates are joined together to form a ring shape, or the third stage is finally reduced by the slide plate of the slippers, and the manufacturing error of each member. In order to prevent unevenness of the lower end surface caused by wear and tear or due to uneven lowering of each slide plate toward the center, the lower end surface 22 a of each slide plate is used.
A concave portion is provided at the appropriate position at the rear of the slide plate, and a convex portion is provided at the lower end of the intermediate and lower sliding plate and the inclined portion 21b of the support h and corresponding to the above. It is desirable that the lower end surfaces of each slide plate be flush with each other when the plate stops descending.

As described above, the moving rod 2 is connected to the center of the upper circumferential end surface of the slide plate to push the slide plate down in order to extend the slide plate and reduce the inner diameter in stages.
Four pieces corresponding to the slide plates divided into five or four parts are installed radially on the horizontal part 21a of the support stand 21, and are slidable only in the radial direction with respect to the support stand. The moving rod 25 can be moved by rotating a rotary ring 26 provided on the moving rod by screwing it into the opening 7 in the horizontal direction, for example, by grasping a handle (not shown) protruding from the outer circumferential surface of the ring. It moves forward and backward in the radial direction.

Reference numeral 28 designates a return pin that is attached to the upper circumferential end surface 22b of the upper layer slide plate at a position where it is impossible to operate the moving rod. It is biased to pull it up in the direction. Then, when the upper slide plate is biased diagonally upward, the upper circumferential end surface 22b of the slide plate engages with the protrusion 23 of the intermediate slide plate, pushing up the intermediate slide plate, and the lower 1- The slide plate is similarly pushed up, and the center portion of the upper circumferential end surface comes into elastic contact with the moving rod. The moving rod 25 is rotated by rotating the rotating ring 26 by kneading.
When the inner diameter is retracted in the radial direction, the inner diameter is not raised sequentially from the upper slide plate, but the diameter is enlarged step by step, contrary to the case where the inner diameter is reduced. In this case, it is a good idea to provide return pins symmetrically on both sides of the moving rod so that the slide plate can be pulled up smoothly with a stable shape in the radial direction. 29 is designed to ensure that the slide plate 29 slides reliably in the radial direction without tilting when the slide plate protrudes against the action of the above-mentioned spring, and that the intermediate and lower slide plates and the support stand slide reliably in the radial direction. Slope part 2 of middle and lower slide plate and support base
This is a guide that engages both ends of the upper slide plate that is protrudingly placed on both ends of 1b and guides the wire part (the first
(See Figure 1).

Adjustment of the inner diameter by this device is carried out in stages by rotating the rotary ring 16 and moving the movable rod 15 forward and backward in the radial direction. When reducing the diameter from the inner diameter or the maximum diameter as shown in Figures 2 to 3, first move the norod 25 inward by rotating one of the upper and lower rotary rings. (see figure 2A), the lower slide plate 22 is pushed and stacked. When the lower slide plates 22 are stacked together and protrude together with the aiming block, and the lower slide plates are joined to each other to form a link shape (at this time F end face 2 of each slide plate
2a is flush with the bottom surface of the support base), and the diameter of the first stage is reduced (see Figure 12B).

When the moving rod 25 is pushed further inward, it will protrude together with the middle slide plate or the slide plates stacked on the outside of it, and each slide plate will become ring-shaped like the lower slide plate, and then it will become two stages. The diameter of the eye is reduced (
(See Figure 7.2C).

Thereafter, the diameter is reduced by the upper slide plate in the same manner (see Fig. 72D). When increasing the inner diameter, the rotating ring 25 is rotated in the opposite direction to that described above to move the moving rod backward.

In the illustrated embodiment, the inner diameter is smaller than DO
The inner diameter can be adjusted in four stages, or by increasing the number of slide plates that can be stacked, the inner diameter can be adjusted in even more stages.

As described above, this ring device can change its inner diameter, so even if the film diameter or swelling ratio changes, it can be easily dealt with and always obtain a film with good transparency. As such, there is no need to replace the air ring with one that fits the stiffness each time. Moreover, this ring device is extremely easy to install because it only needs to be placed on the existing air ring.

Is it possible to always obtain a film with good transparency even when the film diameter or swelling ratio changes using the ring device described above?Is it even more effective if the film is manufactured under the conditions described below? be.

The raw materials used include the following thermoplastic resins commonly used in inflation molding equipment: low density polyethylene (high pressure method, medium pressure method, low pressure method), medium density polyethylene, high density polyethylene, polypropylene (homo, Polyolefins such as poly(1-butene, ethylene and vinyl acetate copolymers), polystyrene, polyvinyl chloride, polyvinylidene chloride, polyamides, polyesters, etc. are used, and low-density polyethylene and Medium-density polyethylene is suitable because it can be used for two-stage cooling to obtain a film with good transparency.

111, low-density polyethylene and medium-density polyethylene produced by medium and low pressure methods are ethylene and 3 to 20 carbon atoms.
a-olefins such as propylene, 1-butene, 1
-Pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-7"ene, ■-tetradecene, 1
A copolymer with -octadecene and, among others, a copolymer with an α,-olefin having 4 to 20 carbon atoms is preferable because a copolymer with excellent transparency can be obtained by a two-stage cooling method.

The distance between the inner peripheral surface of the ring device and the film is 20 to 6
The value is 0+11.

An example of an experiment conducted based on the above conditions is shown below.

In 4 actual examples, ethylene and α-olefin were co-extruded using an extruder (product name: ULTZEX 302/F, manufactured by Mikata Petrochemical Industry Co., Ltd.)
was melted at 77°C and extruded into a tube through a die with a slit diameter/θθφ. Next, the cooling air from the first air ring provided above the die is directed diagonally upward and blown out at an angle of 5 degrees, and then the cooling air is directed diagonally upward from the second air ring provided above the first air ring y3. Blown out at an angle of °. Then, the transparency of the obtained film was measured by adjusting the inner diameter of a diaphragm-type ring device provided in close contact with the upper side of the second air ring. The results are shown in the table below.

The degree of haze was measured according to the method of ASTM-1)-/θθ3.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram of the inflation film forming device. Figure 2 is a plan view of the ring device, and Figure 3 is the A-
A sectional view taken along line A, FIG. 9 a principle diagram of the aperture mechanism, and FIG. 5 showing another example of the ring device, and a plan view shown in FIG. 6! Fig. 2 is a plan view showing yet another example of the ring assembly, Fig. 2 is a sectional view taken along the line A-A of Fig. 2, and Fig. 9 is a cross-sectional view taken along the line C-C of Fig. 2.
The 1st θ is a sectional view taken along the line C-C, and the 1st θ is a plan view of the slide when the slide is pulled up.
2A-2D are diagrams showing the order of operations when changing the inner diameter. A "Ring equipment f3 - First air ring 40 Second air ring 100 units 11... Rotating plate 12... Vane
13J4...Shaft 160 Guide groove 21...Support stand 22...
Slide plate 230 protrusions 250 moving rod 260 rotating ring Ah - Return pin agent Patent attorney Akira Sa Katsu -

Claims (1)

[Claims] (1) The bubble 2 formed by extruding it into a tube shape from the die 1 is first preliminarily cooled with cooling air blown from a first air ring 3 provided above the die 1, and then The above-mentioned blown film forming device is a blown film forming device in which the film is cooled and solidified by cooling air blown upwardly, or diagonally upwardly, from a second air ring 4 provided above the first air ring, and then folded and rolled up. A ring device A is provided above the second air ring, and the ring device A can be changed so that the gap between the bubble and the inner periphery of the ring device is within an appropriate range when the inner diameter or bubble diameter is changed. Air ring (2) ring device [A is a ring-shaped table 1o and a table 1 that is stacked concentrically on the kneading surface and is mounted so as to be slidable in the circumferential direction.
0 and a ring-shaped rotary plate 11 having the same inner diameter as that of guide means 14, which has one end pivoted to the table 10 and the other end provided between the table 10 and the rotary plate 11. Claim 1, which comprises an aperture rod structure comprising a suitable number of blades 12 which are engaged with the rotary plate by 16 and arranged so as to move in a constant locus in a circumferentially overlapping manner. Air link (3) The guide means consists of a guide groove 16 provided on one side of the blade and the rotary plate, and a slider 4 attached to the other side and slidably fitted in the groove. Air ring (4) according to Claim 1 The air ring (6) according to Claim 1, wherein the ring assembly fiA is formed by arranging arcuate pieces having a center of curvature larger than the film diameter in the circumferential direction to form an annular shape. ) The ring device A has a trapezoidal supporting base 21 consisting of an upper surface, a horizontal portion 21 & a sloped portion 21b, and a stop that is flush with the lower end surface or the bottom surface of the support when stacked on the sloped portion of the iron base. A suitable number of funnel-shaped plates, both of which are located at the upper end or an extension of the horizontal part 21a, are divided into several pieces, each of which is divided into individual pieces or slide plates 22 each having an arcuate cross section, and the slide plates 22 are stacked. A spring biases the uppermost slide plate to move radially outward along the inclined surface of the lower slide plate, and a spring biases the upper slide plate of the vertically adjacent slide plates to the lower side. Move the slide plate radially outward along the slope of the plate so that both ends of the lower end, which is the minimum diameter part of the upper slide plate, have the same diameter as the minimum diameter part of the lower slide plate. , and when the upper and lower slide plates are aligned in a straight line at the center of the upper circumferential end surfaces, they will ride as one following the above movement of the lower slide plate or the upper slide plate. It consists of a moving rod 5 connected to the center of the upper circumferential end surface of the plate, and an operating device for moving the moving rod forward and backward in the radial direction, and the spring,
'A stopper means and a moving rod are provided respectively corresponding to the divided individual slide plates. When the moving rod is moved toward the center by the above-mentioned operating device, the slide plate is sequentially extended from the lower part to the upper part, and the inner diameter is gradually reduced, while the moving rod is moved back. The air compressor according to claim 1, further comprising a ring device A, which is configured to gradually extend the sliding plate from the upper part to the lower part by the action of the spring, thereby increasing the inner diameter in stages. Ring (6) A stopper means is provided at a location that does not interfere with the moving rod 25 at the upper end of each slide plate except the top layer slide and plate. l The air ring (γ) operating device 26 according to claim 1 is supported by a protrusion 23 formed on the upper circumferential end face of the adjacent slide plate or on the end face and capable of being locked in a recess. A rotating ring is screwed onto the moving rod 25 arranged radially on the horizontal portion 21a of the table 21, and is adapted to move the moving rod forward and backward by rotating in the horizontal direction. The air ring (8) spring described in claim 8, which is added, is a pair of springs provided symmetrically on both sides of the moving rod 25. First # desired range! Air link described in section