JPH0764021B2 - Film manufacturing method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the production of a film in which the film is run in an oven while gripping both sides in the width direction of the film with clips, and the film is stretched in the oven and then subjected to a relaxation treatment. Regarding the method.

[0002]

2. Description of the Related Art A film, especially a biaxially stretched and biaxially oriented film, is usually subjected to a relaxation treatment under a certain temperature condition in order to maintain its dimensional stability and its heat shrinkage rate. For this relaxation process, normally, for relaxation in the width direction of the film, an oven (stenter device) that stretches the film in the width direction is used, and the distance between the clips holding the film at both ends in the width direction is shortened in the oven. Done. Regarding the relaxation in the longitudinal direction of the film, generally, the roll peripheral speed and the oven are provided between the outlet of the oven and the rolls on the downstream side (for example, the roll for film transport, the cooling roll, the roll for tension cutting, etc.). This is done by making a difference from the running speed of the clip that grips both ends of the film.

However, when the relaxing process is performed between the oven outlet and the rolls on the downstream side, the film being processed is exposed to the outside air (atmosphere), and the outside air temperature fluctuates due to seasonal fluctuations. It may not be possible to reach the target temperature. Therefore, there is a problem that the effect of the relaxation treatment varies, the thermal shrinkage rate of the obtained film in the longitudinal direction varies, and the dimensional stability is impaired.

In order to keep the heat shrinkage ratio in the longitudinal direction at a predetermined value and suppress variations, it is necessary to keep the processing temperature at a predetermined constant value under a predetermined relaxation rate. As a method for satisfying this need, there are known a method of heat treatment by a roll outside the oven instead of the inside of the oven, and a method of performing relaxation in the longitudinal direction of the film inside the oven (Japanese Patent Publication No. 57-54290). ). In this latter method, both ends of the film are cut and separated in the oven before reaching the outlet of the oven, so that the cut central product film portion is relaxed between the inside of the oven and the take-up process on the downstream side of the oven. It is the one. According to this method, the relaxation in the longitudinal direction of the film is performed mainly in the oven which is not affected by the outside air temperature, so that the heat shrinkage rate can be suppressed low and its variation can be suppressed.

[0005]

However, in the above roll heat treatment, the film being relaxed may shrink in the film width direction on the roll, or the film may become sticky to the roll. There is a problem that it causes fire. Further, since the roll heat treatment can perform only the relaxation treatment in the longitudinal direction, there is a problem that a dedicated relaxation treatment device must be provided in addition to the stenter.

On the other hand, the method disclosed in Japanese Examined Patent Publication No. 57-54290 is superior to the roll heat treatment in that it does not have the above problems. However, since the film is cut in the heated state, the tensile strength of the film becomes low, and in the thick film, the self-weight Talmi becomes larger than the contraction stress, and the slack film contacts the parts such as the nozzle of the stenter and becomes the film. There is a problem of scratches. In order to avoid this tarmi, if it is received by a roll in the oven, the problem of scratching due to contact with the roll surface will still occur, and if air floating support is adopted, the air pressure balance on the upper and lower sides of the film will be disrupted and the oven will be damaged. There is a risk that the uniformity of the temperature of the heated air inside will be impaired and the flatness of the film will rather deteriorate. Further, when a thin film is cut at a high temperature, it tends to break in the width direction of the film, which makes stable film formation impossible.

In view of the above-mentioned problems, the present invention makes it possible to relax the film in the width direction and the longitudinal direction while holding the film in the clip in the oven of the stenter, thereby causing scratches or breaks in the film. The purpose is to improve the heat shrinkage rate and flatness of the film without causing it.

[0008]

According to the method for producing a film of the present invention for this purpose, a clip chain in which a large number of chain links are connected in an endless ring shape is run in an oven, and the clip chain is continuously connected to the clip chain. Is a stenter having clips attached to both sides of a film conveyed to, and a joint portion is provided between adjacent clips of the clip chain so that the chain links are bendable with each other, and the joint portion is provided with the joint portion. A guide rail is provided which is provided with an engaging member which is displaced along with the displacement of the joint portion due to the bending, and which bends the chain links on both sides of the joint portion by engaging with the engaging member at a stationary portion in the stenter which does not travel. The film is supplied to the stenter provided with, and the joint part The bending rate of the chain link is adjusted, the relaxation rate in the longitudinal direction of the film is adjusted by adjusting the bending rate, and the longitudinal relaxation process of the film is performed in the stenter. .

That is, in the conventional stenter, no joint is provided between the clips of the clip chain, but in the stenter used in the method of the present invention, a joint portion is further provided at this portion, and both sides of this joint portion are provided. By adjusting the bending rate of the chain link, the distance between adjacent clips can be adjusted.

[0010]

In the stenter used in the method of the present invention, the clip chain portion between the clips has a bendable link structure, and by bending the chain links on both sides of the joint portion, the distance between the adjacent clips can be shortened. Becomes Since the chain links on both sides of the joint portion are bent by engaging the engaging members provided in the joint portion with the guide rails, the guide rails can be bent at appropriate zones in the oven of the stenter, that is, after the stretching zone. In this zone, the distance between the clips is reduced in the oven in the running direction of the clip, and the reduced magnification film is relaxed in the longitudinal direction in the oven while being held by the clip. This relaxation rate is determined by the bending rate of the chain link, that is, how much the joint part (engaging member) is displaced (offset) by the guide rail, and can be arbitrarily adjusted and set within a certain range by setting the position of the guide rail. Is. Therefore,
The film can be relaxed in the longitudinal direction while it is held in the clip without being cut in the oven. In the width direction, it is relaxed by shortening the distance between the clips running on both sides of the film width direction as before. So the width direction in an oven with stable temperature,
Both longitudinal relaxation is possible and the intended purpose is achieved.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the film manufacturing method of the present invention will be described below with reference to the drawings. 1 to 5
Shows a stenter used in a method according to an embodiment of the present invention.

In the figure, reference numeral 1 denotes the entire stenter, and the film 2 is continuously conveyed to the stenter 1 in the direction of the arrow. The stenter 1 is provided with an oven 3 (for example, a hot air oven) and both sides of the film 2 in the width direction,
A clip chain 4 in which a large number of chain links are connected in an endless ring shape is provided. The clip chain 4 travels along rails 5 installed on both sides of the film 2 in the width direction, and the clip chain 4 is provided with a large number of clips 6 for gripping both sides of the film 2 in the width direction.

Although the clips 6 are arranged at an appropriate pitch, there is no clip chain joint between adjacent clips in conventional devices. However, in the stenter used in the method of the present invention, the joint portion 8 for connecting the chain links 7, 7 to each other in a bendable manner is provided between the adjacent clips 6.
Is provided. One of the chain links 7, 7 is connected to a chain link 9 to which a clip 6 having a U-shaped vertical cross section on the upstream side in the traveling direction is attached, and the other chain link 7 is a chain link on the downstream side in the traveling direction. It is connected to 9. The chain link 9 having a U-shaped vertical section travels along the rail 5 via the bearing 10, and therefore the clip 6 attached to the chain link 9 also travels along the rail 5.

In this embodiment, the chain links 7 and 7 are connected to both upper and lower sides of a chain link 9 having a U-shaped vertical cross section. The chain links 7, 7 form a joint portion 8 by being connected via a joint pin 11. Since the chain link 9 travels along the rail 5 via the bearing 10 as described above, the position of the chain link 9 is restricted by the rail 5 in the film width direction, but the joint portion 8 does not move relative to the rail 5. Not bound.

The joint portion 8 is provided with an engaging member 12 which is displaced along with the displacement of the joint portion 8 due to the bending of the chain links 7, 7. Engaging member 12
Is a bearing in this embodiment, and is rotatably attached around the axis of the joint pin 11.

The stationary member of the stenter 1 which does not run, for example, the support rail 13 which supports the rail 5 is engaged with the above-mentioned engaging member 12, and the chain links 7, 7 are engaged by the engagement.
A guide rail 14 is provided that can bend each other. The guide rail 14 extends in the direction along the rail 5 and is installed in a zone behind the stenter 1. This zone 15 is a longitudinal relaxation zone for relaxing the film 2 in the longitudinal direction. In addition, 16 is a width direction relaxation zone, 17 is a heat setting zone, 18 is a drawing zone, and 19 is a preheating zone.

FIG. 5 shows the chain wheel portion at the exit (entrance) of the stenter. No teeth are provided in the portion 21 corresponding to the joint portion 8 of the chain wheel 20, and it corresponds to the chain link 9. The teeth 22 are provided only on the part.

The method of the present invention is carried out as follows using the apparatus configured as described above. When the joint portion 8 is displaced, the chain links 7, 7 are bent together as shown in FIG. The displacement of the joint portion 8 is determined by the engagement member 12
Is engaged with the guide rail 14 and the joint portion 8 is pushed in the clip 6 direction.
In the zone where is not provided, the chain links 7 and 7,
They are in a state where they are fully extended by the tension of the driving force for running the clip chain. When the bearing as the engaging member 12 starts rolling along the guide rail 14, the joint portion 8 is offset inward in the width direction of the film 2 with respect to the chain traveling line, and the chain links 7 and 7 are bent to each other. .

The joint portion 8 is displaced and the chain link 7,
When 7 bends to each other, the distance between the chain links 9, 9 connected to the chain links 7, 7 respectively is reduced and the clip 6 attached to the chain links 9, 9 is reduced.
The distance between them is shortened. The degree of shortening the distance between the clips 6 is the degree of bending of the chain links 7, 7, that is,
It can be adjusted by adjusting the bending rate of the chain links 7, 7. The bending ratio of the chain links 7 and 7 is the guide rail 14
The position adjustment can be adjusted depending on how much the joint portion 8 is displaced. The shortening of the distance between the clips 6 is maintained over the entire region of the longitudinal relaxing zone 15 while the clip 6 holds the film 2, so that the film 2 is relaxed in the longitudinal direction in this zone 15. .

The width relaxing process is carried out in the width relaxing zone 16 and the longitudinal relaxing process is carried out in the longitudinal relaxing zone 15, both of which are carried out in a stable temperature distribution area in the oven 3 while holding the film 2. It is possible to perform a uniform predetermined relaxing treatment without causing scratches or tears on 2. A uniform predetermined relaxation treatment ensures that the target heat shrinkage rate is obtained. Further, since the relaxation treatment is performed while being stretched on the clip, that is, while maintaining a good flat state, a film having excellent flatness can be obtained.

[0021]

As described above, according to the method for producing a film of the present invention, since the two sides of the film can be relaxed in the width direction and the longitudinal direction while the both ends of the film are held by the clips in the oven, Problems such as slack and film scratches due to contact with a nozzle, which are caused by the conventional method, are solved, and a film having excellent heat shrinkage and flatness can be manufactured.

[Brief description of drawings]

FIG. 1 is a plan view of a stenter used for carrying out a method according to an embodiment of the present invention.

FIG. 2 is an enlarged partial plan view of a clip chain portion of the apparatus shown in FIG.

FIG. 3 is a front view of the device of FIG.

4 is a longitudinal sectional view of the device of FIG.

5 is an enlarged partial plan view of a chain wheel portion of the apparatus shown in FIG. 1. FIG.

6 is a plan view showing a state when the chain link of the apparatus of FIG. 2 is bent.

[Explanation of symbols]

 1 Stenter 2 Film 3 Oven 4 Clip chain 5 Rail 6 Clip 7 Chain link 8 Joint part 9 Chain link to which clip is attached 10 Bearing 11 Joint pin 12 Bearing as an engaging member 14 Guide rail 15 Longitudinal relaxation zone 16 Width direction Relaxation zone 18 Stretching zone 20 Chain wheel

Claims (1)

[Claims] 1. A stenter in which a clip chain in which a number of chain links are connected in an endless ring shape is run in an oven, and clips for gripping both sides of a continuously conveyed film are attached to the clip chain. And a joint portion for connecting the chain links to each other in a bendable manner is provided between the adjacent clips of the clip chain, and the joint portion is provided with an engagement member that is displaced along with the displacement of the joint portion due to the bending. Installing the guide rail to the stenter provided with a guide rail that bends the chain links on both sides of the joint portion by engaging with the engaging member at a fixed portion in the stenter that does not run, and installs the guide rail. The bending rate of the chain links on both sides of the joint is adjusted depending on the position, and the flap is adjusted by adjusting the bending rate. A method for producing a film, wherein a relaxation rate in the longitudinal direction of the film is adjusted to perform a relaxation treatment in the longitudinal direction of the film in the stenter.