JPS61160223A - Transversely drawing device of film - Google Patents

Abstract

PURPOSE:To reduce the breakage of a film at transversely drawing process and simultaneously to prevent the trouble of secondary breakage by a method in which the material adhering to clips is sucked, fitting suction mouthes to a transverse drawing device, and the device stopping the suction function simultaneously with its breakage by linking with a breakage detecting signal, is provided. CONSTITUTION:When a transversely drawing device is operated, the suction device connected to suction mouthes 56 has been operated. Then, the material adhering to clips 28 is separated from the clips 28, when the clips pass the adjacency of the suction mouthes 56, and it is extracted outward of the device through the suction mouthes 56 and ducts 58. A film breakage detecting device is provided, and when the breakage of the film is detected, the suction device is quickly stopped and simultaneously. A cover 46a is opened, whereby the winding into of the film is prevented and the secondary breakage of the film is surely prevented.

Description

Detailed Description of the Invention [Industrial Application Field 1] The present invention relates to a film stretching device, and more specifically, a transverse stretching device that performs stretching in a direction perpendicular to the longitudinal direction when producing a biaxially stretched film according to the defter method. The present invention relates to a stretching device that has been improved so as to eliminate troubles caused by breakage and to eliminate foreign matter from entering the film, thereby stably producing a high-quality biaxially stretched film. Note that this lateral stretching device is sometimes referred to as a tenter.

[Conventional technology 1] Today, biaxially stretched films have strong strength, can withstand severe pressure, good dimensional stability, stable quality after processing, and electrical properties and gas barrier properties. Because of its excellent properties, it is used in a wide range of industrial fields, such as for food packaging, magnetic tape, photolithography, and electrical insulation. In addition, the raw materials used are polyester, polystyrene, polypropylene,
There are a wide variety of products including nylon (trademark).

To produce biaxially stretched film according to the tenter method,
Generally, the raw materials are first dried and then melted in an extruder. Then, after passing through a filter etc., it is extruded from a die,
Form into an amorphous sheet using a casting roll or water cooling method. Thereafter, the film is stretched in the longitudinal direction using a longitudinal stretching device, and further stretched in a direction perpendicular to the longitudinal direction while gripping both ends of the film using a horizontal stretching device. Then, it is made into a product by imparting dimensional stability through heat treatment or the like.

FIG. 2 is a diagram showing a schematic configuration of a biaxial stretching apparatus used for this stretching, in which (a) is a side view and (C) is a plan view. Further, (b) is a process diagram, in which the respective processes shown in figures (a) and (e) are shown in correspondence with broken lines.

In FIG. 2, IO is an extruder, and this extruder l
The film l that has undergone the extrusion step ll) from O is sent to a film casting section 13 equipped with a cooling roll 12,
Next, after being longitudinally stretched in a longitudinal stretching device 14 equipped with a heating roll 14a and a stretching roll 14b (step 15), it is laterally stretched in a lateral stretching device 16 (step 17), and then stretched in a winder 18.
The film is wound up (step 19).

The lateral stretching device 16 is movable in synchronization with the oven 20 through which the film 1 is passed and the film 1, and grips both sides of the film 1 as the film 1 passes through the oven 20. It is equipped with a clip that pulls in the width expanding direction (lateral direction). In the figure, reference numeral 22 indicates a clip connection body formed by endlessly connecting clips, and this clip connection body 22 is guided by turntables 24 and 26 installed at the entrance and exit sides of the oven 20.

Note that the clip connectors 22 are installed on both sides of the film l.

The film introduction side of the oven 20 is a heating zone for heating the film l, and the film exit side is a heating zone for heating the film l.
This is a cooling zone for cooling the film 1 after lateral stretching.

[Problems to be Solved by the Invention] As described above, the process of manufacturing biaxially stretched film consists of a combination of many devices, and moreover, it involves two steps of stretching the film in the longitudinal direction and in the transverse direction perpendicular to the longitudinal direction. Due to the harsh stretching operation, it is extremely difficult to form a film without breaking it.

The causes of breakage are: - Air bubbles are mixed into the film due to air being drawn into the screen in the extruder.

■ The molten polymer remains in the melt line and decomposed products are generated, and these decomposed products enter the film.

■ During the casting process, the adhesion between the molten sheet and the drum deteriorates, the extrusion of the molten sheet becomes unstable, and the thickness at both ends of the amorphous sheet becomes irregular.

- In the longitudinal stretching process, the stretching conditions change due to dirt on the rolls over time, the neck-in condition changes and the film width fluctuates.

etc. are possible. Also, ■ If the clip operation becomes defective during the horizontal stretching process, rupture may also occur.

Among these causes, the causes of breakage in the extrusion process, casting process, and longitudinal stretching process (■ to ■) are clear, so for example, the screw structure should be improved, the filter maintenance method, and some parts of the filter should be improved. Some measures can be taken by considering the structure and optimizing the conditions.

Regarding the breakage in the transverse stretching step (2), the main cause of the breakage was poor gripping with the clip.

That is, since the heating zone of the oven 20 is at a relatively high temperature (approximately 230° C. in the case of a polyester film), sublimable low molecular weight substances within the film 1 are likely to precipitate on the film surface.

This low-molecular-weight substance becomes powder in the cooling zone within the oven 20 and adheres to clips and the like.

Furthermore, the lubricating oil in the clip also deteriorates due to heat, and products of the deterioration adhere to the clip.

If such deposits become sticky, the clip may not be gripped properly and the film is likely to break.

Furthermore, if the adhesion lasts for a long time, the adhesion may partially peel off and scatter on the film, resulting in a negative effect of degrading the film quality.

Therefore, any deposits on the clip should be removed promptly. However, in reality, it takes a lot of time and money to maintain the clips, so it is difficult to maintain them once or twice.
This can only be done once a year, so it is not enough to deal with it. Therefore, during this time, substances such as degraded lubricating oil and low molecular weight substances precipitated from the film adhere to the clip, and the operating condition gradually deteriorates, making it impossible to grip the clip sufficiently and increasing the frequency of breakage.

To date, there have been various proposals for modifying the clip mechanism for the purpose of stabilizing the gripping of the clip, but there has been no effective proposal for a method to stably support the operating state of the clip over a long period of time. It was not possible to reduce the breakage.

Furthermore, in the transverse stretching process, some fractures may be induced by fractures caused by causes other than malfunction of the clip. That is,
When the film breaks due to some other cause, the broken pieces enter the clip gripping portion, making it impossible to grip the film sufficiently, causing the clip to become dislodged, resulting in a larger secondary break.

By the way, users who process these biaxially stretched films have been increasing the size of their processing equipment, and the use of high-precision processing has also increased. As a result, wide, long, and seamless products are now required, and when breakage occurs, productivity is significantly reduced.

Furthermore, in recent years, film forming equipment has become larger, and the equipment has also become increasingly complex in order to apply coatings on reline lines that produce films with high resistant properties. It takes a considerable amount of time to return, and eliminating breakage has become a major problem in improving productivity.

Furthermore, if sublimable substances such as low-molecular acid substances adhere to and accumulate on the clip, they may fall off and get mixed into the film when the clip makes a sudden movement (turn) at the turn section of the clip. . If foreign matter gets mixed into the product in this way, there is a risk that it will cause trouble in the processing process when the film is processed into various products, or that the quality of the processed product will deteriorate.

The present invention solves the above-mentioned conventional problems, and provides a film stretching device that can reduce breakage in the transverse stretching process, prevent secondary breakage troubles, and further prevent sublimates from being mixed into the film. is intended to provide.

Means for Solving Problem E] The present invention includes attaching a suction port to the lateral stretching device to suction the deposits on the clip, and further installing equipment that works in conjunction with a break detection signal to stop the suction function at the same time as the break occurs. According to
The structure is such that the operation of the clip can always be maintained normally, thereby greatly reducing breakage, reducing the frequency of foreign matter entering the film, and significantly improving the quality of the product.

That is, the present invention has an endless clip connecting body formed by endlessly connecting a large number of clips for gripping the side of the film, and this connected body is configured to grip the side of the film along the side of the film fed in the longitudinal direction. In a film transverse stretching device that is installed to be able to travel at the same speed as the film feed speed, a suction device is installed, and the suction port of the suction device is connected to the clip opening/closing portion of the inlet and/or outlet of the transverse stretching device. A film lateral stretching device characterized in that it is provided in.

and an endless clip connection body formed by endlessly connecting a number of clips for gripping the sides of the film, and this connection body moves along the sides of the film fed in the longitudinal direction at the same speed as the film feeding speed. In a film transverse stretching device that is installed to be able to run at high speed, a suction device is installed, and a suction port of the suction device is provided in the input part and/or the clip opening/closing part of the exit part of the horizontal stretching device. , a film lateral stretching device, characterized in that a film break detection device is installed, and the suction function of the suction device is stopped by a break detection signal from the break detection device. It is.

[Function] The main causes of breakage in the transverse stretching process of biaxial stretching equipment are due to the oil used for clip lubrication adhering to the clip and deteriorating, or the above-mentioned sublimable low molecular acid substances adhering to the clip. This is due to the clip not working properly and not being able to grip it properly.

Furthermore, if the operation continues without removing these deposits, they will gradually solidify and adhere to the clip surface in a layered manner, making it extremely difficult to remove them. If it continues for a longer period of time, it will start to peel off partially and scatter on the film.

According to the present invention, such adherents are removed before they solidify. Therefore, the clip always operates normally. It also prevents deterioration in film quality due to peeled objects.
be done.

Furthermore, according to the present invention, even if a piece of film gets into the clip, it can be removed immediately, so that poor gripping caused by broken film pieces getting into the gripping part and secondary breakage caused by this can be prevented. I can do it.

[Example] Examples will be described below with reference to the drawings.

FIG. 1 is a schematic plan view of a lateral stretching device according to an embodiment of the present invention. The configuration of the main parts of Figure 1 is shown in Figure 2 (C
), the oven 20 extends in the feeding direction of the film 1, and the film 1 is passed through the oven 20;
The clips are connected in an endless manner, and are provided with clip connecting bodies 22 installed on both sides of the film 1 to pull the film 1 in the lateral direction, and turntables 24 and 26 guiding the clip connecting bodies 22 to be sent back.

Inside the oven 20, from the entrance side of the film l,
It is divided into a preheating zone A, a stretching zone B, a heat treatment zone C, and a cooling zone.

As shown in FIG. 3, the clip connecting body 22 has a large number of clips 28 connected endlessly by a chain 30, and is driven by a turntable 24, 26 and moves along the film l as shown by the arrow. Travels in the feed direction.

□The clip 28 includes a clip main body 32 and a lever 34 pivotally supported by the clip main body 32, as shown in FIG.
One end 32a of the clip body 32 and the tip 34a of the lever 34 are biased in the clamping direction by an elastic member (not shown) such as a spring, and the one end 32a of the clip body 32 and the tip 34a of the lever 34 are Grip the sides of the film 1 between them.

When starting to grip the film or releasing the gripped film, the rear end 34b of the lever 34 is pushed downward in the figure to separate one end 32a of the clip body from the lever tip 34a. Although not shown, an opener for pushing down the rear end 34b of the lever 34 is provided at the part of the inlet side turntable 24 that meets the film l and the part of the outlet side turntable 26 that separates from the film l. A lever actuation mechanism is provided.

FIG. 5 is a horizontal cross-sectional view showing the internal structure of the oven 20. As shown, the clip 28 is attached to a guide rail 36
．． 38 is sliding. Then, the stretching band B of the film L
In this case, the guide rails 36 and 38 are installed so as to gradually move away from each other in the film feeding direction.
The clip 28 that is moved on this stretching band is attached to the guide rail 3
6. Guided by 38, forcibly shifted in the direction of separation,
This causes the film 1 to be stretched in the transverse direction. In addition,
Outside the stretch band B, the guide rails 36, 38 are substantially parallel.

As schematically shown in FIG. 5, in the oven 20, air blowers 40 and 42 are installed vertically facing each other for blowing hot air or cooling air toward both the upper and lower surfaces of the film 1. In the preheating zone A, stretching zone B, and heat treatment zone C, the film is heated to a predetermined temperature using hot air.
heat up.

In addition, in the cooling zone downstream of the heat treatment zone C in the film feeding direction, cooling air is blown out instead of the hot air for 1 hour.

In this embodiment, the clip connector 22 is inserted into the cover 44, as shown in FIGS. 5 and 6. This cover 44 consists of a side cover 46 and a lower side cover 48 (see Fig. 5), and the -1- side cover 46 is divided into two halves long in the film feeding direction, and is connected to a connecting member 50 such as a hinge. It consists of half bodies 46a and 46b that are tied together (see diagram ilRB).

As shown in FIGS. 6 and 7, a cylinder mount 52 is installed on the -L surface of the half body 46b located on the outside in the film transverse direction, and a cylinder 54 is pivotally supported.

The cylinder 54 is installed in the transverse direction of the film, that is, in the short direction of the cover, and the tip of the rod 54a is pivotally attached to the L-plane end of the other half body 46a. Therefore, when the cylinder 54 is actuated to retract the rod 54a, the cover half body 46a opens upward with the connecting member 50 as the center of rotation.

On the other hand, in the device of this embodiment, as shown in FIGS. 1, 6, and 8, suction ports 56 are provided in the clip opening/closing portions at both ends of the cover 44. It is connected via a duct 58 to a suction device (not shown). (Incidentally, an annual production device may be installed on the second-stream side and/or downstream side of the suction device.) Furthermore, in the device of this embodiment, a device for detecting breakage of the film l is installed, and When a break is detected, the suction device is stopped. At the same time, the cylinder 54 is actuated, and the cover half body 46a opens upward with the connecting member 50 as the center of rotation. In this embodiment, the film breakage detection device uses a mechanism that constantly measures the stretching load of the transverse stretching device and detects a state in which the stretching load becomes less than a predetermined value to detect breakage. This mechanism is quick to respond. Of course, other mechanisms may be used, for example, film sensing means such as phototubes may be provided before and after the oven 20, and the film sensing means may be configured to detect the occurrence of a break by checking the presence or absence of the film. Equipment etc. may also be adopted.

Next, the operation of the apparatus according to the embodiment will be explained.

The film l stretched in the longitudinal direction by the longitudinal stretching machine is introduced into the oven 20 with its both sides held by the clips 28 of the endless clip connector 22 . After being preheated in the preheating zone A in the oven 20, the film is stretched in the transverse direction (film width direction) in the stretching zone B. Next, after being subjected to heat treatment in heat treatment zone C and cooling treatment in cooling zone,
Exit oven 20.

After the film l has left the oven 20, the clips 28 that were gripping both sides of the film l are disengaged from the clips 28 by rotating the lever 34 in the opposite direction by an opener (not shown). It is sent to the winding process.

When this lateral stretching device is operated to face the patient, a suction device (not shown) connected to the suction port 56 is operated. Then, the substance attached to the clip 28 is
When the clip 28 passes near the suction port 56, it is separated from the clip 28, and the suction port 56 and the duct 58 are separated.
It is extracted from the inside of the cover 44 to the outside of the apparatus. As mentioned above, these deposits are the sublimable low molecular weight substances in the film 1 that are precipitated into powder by heating the film 1, or the deterioration of the lubricating oil, and if left for a long time, According to the present invention, this deposit, which causes a hindrance to the gripping operation of the clip, is quickly removed.
Malfunction of the clip caused by this is prevented.

Furthermore, if these deposits were attached to the clip 28 for a long period of time, they would peel off in layers and scatter, adhering to the film l and degrading its quality. However, according to the present invention, the deposits can be removed. Since it is quickly removed, such deterioration in film quality is also avoided.

The breakage of the film 1 was also caused by causes other than the above-mentioned deposits. In other words, if a break occurs due to some other reason, the gripping part of the film breaks and is brought into the clip (gripping part), or if the film is thin, especially 61L or less, the film has no stiffness and the film may not be able to fit inside the cover. This is a secondary fracture that occurs when the material gets caught up and enters the gripping part. These film entanglements were facilitated by the fact that the clip ran inside the cover at high speed, causing the inside of the cover to be slightly depressurized, but in the present invention, the inside of the cover 44 is suctioned by a suction device. There is a possibility that such secondary fractures will increase.

However, in this embodiment, a film breakage detection device is provided, and when a breakage of the film l is detected, the suction device is immediately stopped and the cover 46a is opened, so that the above-mentioned film entrainment is prevented. , secondary breakage is also reliably prevented.

In addition, in the present invention, it is more effective if the specifications are determined so that the pressure near the suction port is 150 mmAq or more lower than atmospheric pressure and the suction air volume is 30 rn"/min or more. .

Furthermore, the apparatus of the present invention is extremely effective for producing films with a thickness of 121 Lm or less, especially 6 gm or less.

Using the device of the present invention as a transverse stretching device of a polyester biaxial stretching device, films with a thickness of 5 to 27 Lm were produced for about one year, but no sublimable low molecular weight substances were found to be attached to the clips, and conventional clips After 6 months of maintenance, the breakage that had been occurring once a day stopped, and it has been able to be used stably for about a year. In addition, the frequency of secondary fractures has decreased significantly, from an average of 23 fractures per month to 5 71 fractures per month. At the same time, the amount of foreign matter mixed into the film was significantly reduced, and a significant improvement was seen in terms of quality.

[Effects] As detailed above, according to the transverse stretching apparatus of the present invention, breakage of the film can be prevented, and productivity is dramatically improved. Furthermore, the quality of the film is also improved.

[Brief explanation of the drawing]

FIG. 1 is a plan view of an apparatus according to an embodiment of the present invention. Figure 2 shows the configuration of the biaxial stretching device.
&) is a side view, Figure 2 (b) is a block diagram, Figure 2 (C
) is a plan view. 3 and 6 are enlarged views of the main parts of the embodiment device, FIG. 4 is a side view of the clip 28, FIG. 5 is a cross-sectional view of the main parts of the embodiment device, and FIG.
FIG. 8 is a cross-sectional view taken along the line ■-■ in FIG. 6, and FIG. 8 is a cross-sectional view taken along the line ■--■ in FIG. 16... Lateral stretching device, 20... Oven, 22
...Endless clip connection body, 28...Clip, 34...Lever, 44
...-) J/<+, 54... cylinder, 56...
Suction port.

Claims (3)

[Claims] (1) It has an endless clip connection body formed by endlessly connecting a large number of clips for gripping the sides of the film, and this connection body moves the film forwarding speed along the sides of the film fed in the longitudinal direction. A suction device is installed in a film lateral stretching device that is installed to run at the same speed as the lateral stretching device, and the suction port of the suction device is provided at the clip opening/closing portion of the inlet and/or outlet of the lateral stretching device. A film lateral stretching device characterized by: (2) The film lateral stretching apparatus according to claim 1, wherein the endless clip connector is covered with a cover, and the suction port is opened in the cover. (3) It has an endless clip connecting body formed by endlessly connecting a large number of clips for gripping the side of the film, and this connected body moves along the side of the film fed in the longitudinal direction at the film feeding speed. In a film transverse stretching device that is installed to be able to travel at the same speed as the horizontal stretching device, a suction device is installed, and a suction port of the suction device is provided at a clip opening/closing portion of the inlet and/or outlet of the horizontal stretching device; 1. A film transverse stretching apparatus, characterized in that a film break detection device is installed, and the suction function of the suction device is stopped by a break detection signal from the break detection device.