JPH0428218B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention involves running a sheet-like article into an oven while gripping both widthwise sides of the sheet-like article with clips. This invention relates to the structure of a stent that performs treatments such as stretching and relaxing.

[Prior Art] Sheet materials, particularly biaxially stretched and biaxially oriented films, are usually subjected to a relaxation treatment under certain temperature conditions in order to maintain their dimensional stability and keep their thermal shrinkage rates low. . In this relaxing process, an oven (stenter device) that stretches the film in the width direction is usually used to relax the film in the width direction, and the distance between the clips that grip the film at both ends in the width direction is shortened in the oven. It will be done. Relaxation in the longitudinal direction of the film is generally determined by adjusting the circumferential speed of the rolls and the rolls installed in the oven between the oven exit and the rolls downstream thereof (for example, film transport rolls, cooling rolls, tension cutting rolls, etc.). This is done by creating a difference in the running speed of the clips that grip both ends of the film.

However, when relaxing processing is performed between the oven outlet and the roll downstream from the oven outlet, the film being processed is exposed to the outside air (atmosphere), and the outside temperature varies due to seasonal fluctuations, so it is difficult to set the target processing temperature. It may not be possible to reach the desired temperature. Therefore, there are problems in that the effect of the relaxing treatment varies, the thermal shrinkage rate of the obtained film in the longitudinal direction varies, and dimensional stability is impaired.

In order to keep the thermal contraction rate in the longitudinal direction within a predetermined value and suppress variations, it is necessary to maintain the processing temperature at a predetermined constant value under a predetermined relaxation rate. As methods to meet this need, there are two known methods: heat treatment using rolls outside the oven rather than inside the oven, and a method that also involves relaxing the film in the longitudinal direction inside the oven.
57-54290). In this latter method, both ends of the film are cut and separated in the oven before reaching the oven outlet, and the cut central product film is allowed to relax between the inside of the oven and the take-up process downstream of the oven. This is what I did.
According to this method, relaxation in the longitudinal direction of the film is mainly performed in an oven that is not affected by outside temperature, so that the thermal shrinkage rate can be kept low and its variation can be suppressed.

[Problems to be solved by the invention] However, first, in the roll heat treatment,
During the relaxation process, the film shrinks in the film width direction on the roll, and the film tends to stick to the roll, resulting in wrinkles in the film. Further, since roll heat treatment can only provide relaxation treatment in the longitudinal direction, there is a fundamental problem in that a dedicated relaxation treatment device must be provided in addition to the stenter.

On the other hand, the method disclosed in Japanese Patent Publication No. 57-54290 is superior to roll heat treatment in that it does not have the above-mentioned problems. However, since the film is cut under heating, the tensile strength of the film becomes low, and for thick films, the self-weight sag becomes larger than the shrinkage stress, and the sagging film comes into contact with various parts such as the nozzle of the stent, causing the film to break. There is a problem that scratches occur. To avoid this sagging,
If the film is supported by a roll in the oven, there will still be the problem of scratches due to contact with the roll surface.If air floating support is used, the air pressure balance between the top and bottom sides of the film will be disrupted and the heated air in the oven will be affected. Temperature uniformity may be impaired, and the flatness of the film may actually deteriorate. Furthermore, if a thin film is cut at a high temperature, it will easily break in the width direction of the film, making stable film formation impossible.

In view of the above-mentioned problems, the present invention makes it possible to perform relaxation treatment in both the width direction and the longitudinal direction while the sheet-like object is held by the clip in the oven of the stenter, thereby preventing scratches or breaks on the sheet-like object. The purpose is to improve the heat shrinkage rate and flatness of sheet-like products without causing any problems.

[Means for Solving the Problems] The stenter of the present invention that meets this objective runs a clip chain in which a large number of chain links are connected in an endless ring in an oven, and is continuously conveyed to the clip chain. In a stentter equipped with clips for gripping both sides of a sheet-like object, a joint portion is provided between adjacent clips of the clip chain to connect the chain links in a bendable manner, and the joint portion is provided with a joint portion that bends the chain links together. An engaging member that displaces with the displacement of the joint part is provided, and a guide rail is provided at a fixed part in the stenter that does not travel, which bends the chain links on both sides of the joint part by engaging with the engaging member. Become.

That is, in the conventional stenter, no joint was provided between the clips of the clip chain, but in the present invention, a joint is further provided in this region.

[Function] In such a stentter, the clip chain portion between the clips has a bendable link structure, so by bending the chain links on both sides of the joint portion to each other, it is possible to shorten the distance between adjacent clips. Become. The chain links on both sides of the joint are bent by engaging the engagement members provided on the joint with the guide rail, so if the guide rail is installed in an appropriate zone in the oven of the stenter, it will be bent. The distance between the clips is reduced in the direction in which the clips travel, and the sheet material is relaxed in the longitudinal direction in an oven while being held by the clips by the reduced magnification. 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 set arbitrarily within a certain range by setting the position of the guide rail. It is. Therefore, it is possible to relax the sheet material in the longitudinal direction while it is held in the clips without cutting it in the oven, and in the width direction, the distance between the clips running on both sides in the width direction of the sheet material is the same as in the conventional method. Since the relaxation treatment is performed by shrinking the material, it is possible to perform the relaxation treatment in both the width direction and the longitudinal direction in an oven at a stable temperature, thereby achieving the desired purpose.

[Embodiments] Preferred embodiments of the stenter of the present invention will be described below with reference to the drawings.

FIGS. 1 to 5 show a stenter according to an embodiment of the present invention, in which the present invention is applied to a stenter for plastic film as a sheet-like product.

In the figure, 1 indicates the entire stenter,
A 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 a clip chain 4 provided on both sides in the width direction of the film 2 and having a large number of chain links connected in an endless ring shape. The clip chain 4 runs along rails 5 installed on both sides in the width direction of the film 2, and a large number of clips 6 are attached to the clip chain 4 for gripping both sides of the film 2 in the width direction, respectively.

The clips 6 are arranged at a suitable pitch, but in conventional devices there is no clip chain joint between adjacent clips. However, in the present invention, a joint portion 8 is provided between adjacent clips 6 to connect the chain links 7 to each other in a bendable manner. One chain link 7 of the chain links 7, 7 is connected to a chain link 9 on the upstream side in the running direction to which a clip 6 having a U-shaped longitudinal section is attached, and the other chain link 7 is connected to a chain link 7 on the downstream side in the running direction. It is connected to 9. The chain link 9, which has a U-shaped longitudinal section, runs along the rail 5 via a bearing 10, and therefore the clip 6 attached to the chain link 9 also runs along the rail 5.

In this embodiment, the chain links 7, 7 are connected to both upper and lower sides of a chain link 9 having a U-shaped longitudinal section. Chain links 7, 7 are joint pins 1
1, the joint portion 8
It consists of Since the chain link 9 runs along the rail 5 via the bearing 10 as described above, its position is restrained by the rail 5 in the film width direction, but the joint portion 8 is is not positionally constrained.

This joint part 8 has chain links 7, 7.
An engaging member 12 is provided which is displaced along with the displacement of the joint portion 8 as the joint portion 8 is bent. In this embodiment, the engaging member 12 is a bearing, and is rotatably mounted around the axis of the joint pin 11.

A guide rail that engages with the engagement member 12 at a fixed portion of the stent 1 that is not run, such as the support rail 13 that supports the rail 5, and is capable of bending the chain links 7, 7 to each other by the engagement. 14 are provided. Guide rail 14
extends in the direction along the rail 5 and is installed in the rear zone of the stenter 1. This zone 15 serves as a longitudinal relaxation zone in which the film 2 is relaxed in the longitudinal direction. In addition, 16 is a width direction relaxation zone, 17 is a heat setting zone, 18 is a stretching zone, and 19 is a preheating zone.

In addition, FIG. 5 shows the chain wheel part at the stenter outlet (inlet) part, and the chain wheel 2
No teeth are provided in the portion 21 corresponding to the joint portion 8 of No. 0, and teeth 22 are provided only in the portion of the chain link 9.
is provided.

The operation of the embodiment device configured as described above will be explained below.

When the joint portion 8 is displaced, the chain links 7, 7 are bent toward each other as shown in FIG.
The displacement of the joint part 8 occurs when the engaging member 12 engages with the guide rail 14 and the joint part 8 engages with the clip 6.
In the zone where the guide rail 14 is not provided, the chain links 7, 7 are in a fully extended state due to the tension caused by 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 running line, and the chain links 7, 7 are bent to each other. .

When the joint portion 8 is displaced and the chain links 7, 7 are bent to each other, the distance between the chain links 9, 9 connected to the chain links 7, 7 is shortened, and the clips attached to the chain links 9, 9 are shortened. The distance between 6 is shortened. This shortening of the distance between the clips 6 means that the film 2 is attached to the clip 6.
while holding the longitudinal relaxation zone 15.
In this zone 15, the film 2 is relaxed in the longitudinal direction.
The width direction relaxation treatment is performed in the width direction relaxation zone 16, and the longitudinal direction relaxation treatment is performed in the longitudinal direction relaxation zone 15, both of which are performed in an area with stable temperature distribution in the oven 3 while the film 2 is being gripped. It is possible to uniformly and predetermined relaxation treatment without causing scratches or tears on 2.

[Effects of the Invention] As explained above, when using the stenter of the present invention, it is possible to perform longitudinal relaxation treatment on the sheet-like object while it is held in the oven by the clips. This makes it possible to perform the specified longitudinal relaxation treatment without causing quality defects or process troubles such as scratches or breaks, and it is possible to easily obtain the target low longitudinal heat shrinkage rate, as well as to improve the flatness of the sheet material. This has the effect of improving sexual performance.

[Brief explanation of drawings]

1 is a plan view of a stenter according to an embodiment of the present invention, FIG. 2 is an enlarged partial plan view of the clip chain part of the device shown in FIG. 1, FIG. 3 is a front view of the device shown in FIG. 2, and FIG. The figure is a longitudinal sectional view of the device shown in FIG. 2, FIG. 5 is an enlarged partial plan view of the chain wheel section of the device shown in FIG. 1, and FIG. 6 shows the state when the chain link of the device shown in FIG. 2 is bent. FIG. DESCRIPTION OF SYMBOLS 1...Stenter, 2...Film as a sheet-like material, 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, 1
5... Longitudinal relaxation treatment zone, 16...
Width direction relaxation treatment zone, 18...stretching zone, 20...chain wheel.

Claims (1)

[Claims] 1. In a stenter, a clip chain in which a large number of chain links are connected in an endless ring is run in an oven, and clips are attached to the clip chain to grip both sides of a sheet-like object that is continuously conveyed. A joint part is provided between the clips to bendably connect the chain links to each other, and an engaging member is provided in the joint part to be displaced along with the displacement of the joint part due to the bending, and the joint part is provided with an engaging member that is displaceable in accordance with the displacement of the joint part due to the bending. A stent, characterized in that a guide rail is provided at a portion thereof to bend the chain links on both sides of the joint portion by engaging with the engaging member.