JPH0623838A - Production of sheet like article - Google Patents

Abstract

PURPOSE:To enhance the heat shrinkage factor and flatness of a sheet like article while preventing trouble such as a damage or breakage and achieving stable film formation by grasping both ends of the sheet like article to preheat and stretch the sheet like article while allowing the sheet like article to run through a stenter and subsequently thermally setting the stretched sheet like article to subject the same to relax treatment. CONSTITUTION:A sheet like article 2 is preheated, stretched and thermally set in a stenter 1 and subsequently subjected to relax treatment. Herein, the relax treatment consists of lateral relax treatment contracting the running passage of a pair of the clip chains 4 arranged on both sides of the sheet like article in the lateral direction thereof and longitudinal relax treatment pushing the joint part where chain links are mutually connected in a bendable manner between the adjacent clips of the clip chains 4 toward the center direction of a pair of the clip chains 4 by the guide rails 14 engaged with the joint part to contract the interval between the adjacent clips in the running direction of the sheet like article. As mentioned above, relax treatment is performed in both of the lateral and longitudinal directions of the sheet like article.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention runs a sheet material in an oven of a stenter while gripping the widthwise both sides of the sheet material with clips, and preheats and stretches the sheet material in the oven. The present invention relates to a method for producing a sheet-like material which is subjected to a relaxation treatment after heat setting.

[0002]

2. Description of the Related Art In the case of a sheet material, particularly a biaxially stretched film which is biaxially oriented, in order to maintain its dimensional stability and a low heat shrinkage ratio, it is usually stretched, heat set and then subjected to a certain temperature condition. Relaxation treatment is given in. 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 that grip the film at both ends in the width direction 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 the slack of its own weight becomes larger than the contraction stress in the thick film,
There is a problem that the loosened film comes into contact with each part of the stenter, such as the nozzle, and scratches the film. In order to avoid this slack, if it is received by the 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 lost and the oven 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 sheet-like material in the width direction and the longitudinal direction in the oven of the stenter while gripping the sheet-shaped material with the clip, and in both directions. An object of the present invention is to improve the heat shrinkage rate and flatness of the sheet-like material while achieving stable film formation by performing the relaxation treatment without causing troubles such as scratches and breaks in the sheet-like material.

[0008]

According to the method for producing a sheet-like article of the present invention which meets this object, a sheet-like article is formed in an endless annular shape with a large number of chain links arranged on both sides in the width direction of the sheet-like article. A sheet attached to clips connected to a pair of connected clip chains so that both ends of the clips are made to travel in a stenter, and in the stenter, preheating, stretching, heat fixing, and then relaxing treatment are performed. In the manufacturing method described above, (a) the relaxing process in the width direction of the sheet-like material, which is performed by reducing the traveling paths of the pair of clip chains in a tapering shape in the traveling direction, and (b) the clip. A joint portion formed by connecting chain links between adjacent clips of a chain so as to be bendable with each other is provided with a pair of guide rails engaging with the joint portion. By pressing in the central direction of the clip chain, the performed allowed reducing the spacing between adjacent clips in the direction of travel, the longitudinal relaxation process of said sheet comprises a method, characterized in that consist.

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 this joint portion is provided. By pushing the guide rails toward the center of the pair of clip chains, it is possible to bend the chain links on both sides of the joint portion and reduce the distance between the adjacent clips.

[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 interval 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 are set at appropriate zones in the oven of the stenter, that is, stretching and heat fixing zones. If it is installed in an appropriate zone thereafter, the inter-clip interval is reduced in the oven in the clip running direction, and the reduced sheet-like material is relaxed in the longitudinal direction in the oven while being held by the clip. Therefore,
The sheet material is preheated, stretched, and stretched in a stenter oven.
After heat fixing, the clip chain travel path is tapered in the travel direction in the same manner as in the conventional method to relax in the width direction and cut the sheet material in the oven in the longitudinal direction as well. Without being gripped by the clip, it is relaxed. Since it is relaxed while being held by the clip, the sheet does not loosen or come into contact with nozzles, etc., and is relaxed in both the width and length directions in an oven with a stable temperature. The target heat shrinkage rate and good flatness can be stably obtained.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the method for producing a sheet-like material of the present invention will be described below with reference to the drawings. 1 to 5 show a stenter used in a method according to an embodiment of the present invention, and show a case where the method of the present invention is applied to an apparatus for producing a plastic film as a sheet.

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. Reference numeral 16 is a width-direction relax zone in which the travel path of the clip chain 4 is tapered in the travel direction. Reference numeral 17 is a heat setting zone, 18 is a stretching 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. As shown in FIG. 1, the film 2 introduced into the stenter 1 (the film already stretched in the longitudinal direction in the previous step) is preheated to a predetermined temperature in the preheating zone 19 in the oven 3, and the width is stretched in the stretching zone 18. The film is stretched in a predetermined direction at a predetermined ratio and heat-set in the heat-setting zone 17 at a predetermined temperature. Then, in the widthwise relaxing zone 16, first, a relaxation treatment is performed in the widthwise direction. This relaxing process in the width direction is performed in the same manner as the conventional method, that is, by reducing the running path of the clip chain 4 in the running direction by tapering, the clips 6 holding the film 2 on both sides in the width direction are held. The width of the film 2 is shortened by a predetermined relaxation rate by shortening the distance between the two.

After the relaxation treatment in the width direction, the relaxation treatment in the longitudinal direction is performed in the longitudinal relaxation zone 15. In this longitudinal relaxation process,
Although the joint portion 8 is displaced, when the joint portion 8 is displaced, the chain links 7, 7 are bent to each other 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, that is, in the center direction of the pair of clip chains 4 arranged on both sides in the width direction of the film 2. In the zone where the guide rail 14 is not provided, the chain links 7 and 7 are in a state where they are fully extended by the tension due to the driving force for traveling 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 together, the distance between the chain links 9, 9 respectively connected to the chain links 7, 7 is reduced and the distance between the adjacent clips 6, 6 attached to the chain link 9, 9 is reduced. . The degree of shortening the interval between the adjacent clips 6 can be adjusted by adjusting the degree of bending of the chain links 7, 7, that is, the bending rate of the chain links 7, 7. The bending ratio of the chain links 7, 7 can be adjusted by adjusting the position of the guide rail 14 and by 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 kept in this zone 15.
Is longitudinally relaxed.

The width-direction relaxing process is carried out in the width-direction relaxing zone 16 and the longitudinal direction 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 6, that is, while maintaining a good flat state, a film having excellent flatness can be obtained.

[0022]

As described above, according to the method for producing a sheet-like article of the present invention, a relaxation treatment in two directions, the width direction and the longitudinal direction, is performed while holding both ends of the sheet-like article in the oven with clips. Therefore, the problem of slackening and scratching of a sheet-like material due to contact with a nozzle, etc. as in the conventional method is solved, and a sheet excellent in heat shrinkage and flatness is achieved while achieving stable film formation. It is possible to manufacture a product.

[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 as a sheet 3 Oven 4 Clip chain 5 Rail 6 Clip 7 Chain link 8 Joint part 9 Chain link to which the clip is attached 10 Bearing 11 Joint pin 12 Bearing as an engaging member 14 Guide rail 15 Longitudinal relaxation Treatment zone 16 Width direction relaxation treatment zone 18 Stretching zone 19 Preheating zone 20 Chain wheel

Claims (1)

[Claims] 1. A sheet-shaped object is gripped at both ends by a clip attached to a pair of clip chains, which are arranged on both sides in the width direction of the sheet-shaped object and in which a large number of chain links are connected in an endless annular shape. While running in the stenter, in the stenter, in the sheet-like material manufacturing method of preheating, stretching, then heat setting, and then relaxing treatment, the relaxing treatment includes (a) the pair of clip chains. Relaxing treatment in the width direction of the sheet-like material by tapering down the traveling path in the traveling direction, and (b) chain links between adjacent clips of the clip chain being bendably connected to each other. By pushing the joint portion toward the center of the pair of clip chains by the guide rails that engage with the joint portion, the adjacent clip And a relaxing treatment in the longitudinal direction of the sheet-shaped article, which is performed by reducing the distance between the groups in the running direction.