JPH03102058A - Non-contact transport device for web - Google Patents

Abstract

PURPOSE:To stably float and transport a web without generation of wrinkles and without contact with nozzles, even if the web has low rigidity, by using gas blow-out nozzles having gas ejecting slits which one of two slits is closed at the center part in the width direction of the web. CONSTITUTION:A web 1 is wave-likely floated with gas blow-out nozzles 2 which are alternately arranged on the upper and lower side so as to pinchedly hold the web between. The respective gas blow-out nozzles 2 have respectively two gas ejecting slits 3 on both edges. One of the two gas ejecting slits 3 is provided with a baffle plate 4 on the center part in the width direction of the web so as to unify pressure distribution between the nozzle and the web in the width direction of the web. The baffle plate 4 is formed out of a plate having a certain thickness on the gas ejecting plane of the gas blow-out nozzle 2 so as to cover the gas ejecting slit.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a non-contact conveying device for a long strip-shaped support (hereinafter referred to as a "web") such as a plastic film or paper. In particular, photosensitive materials such as photographic film and photographic paper, photoengraving materials, magnetic recording materials such as magnetic recording tape, pressure-sensitive copying paper,
This paper relates to a non-contact transport device for continuously running webs for recording materials such as thermal copying paper. [Prior Art] Devices using rollers have been widely used as a method of conveying webs such as plastic films and paper. may cause scratches, wrinkles, etc., and damage the product. In addition, in the case of webs with coating films on both sides, the quality is particularly affected, so as a countermeasure, a device is used that blows gas against the web and uses the pressure of the gas to levitate the web and convey it without contact. ing. In these non-contact conveying devices for webs, static pressure support type gas blowing nozzles are arranged so as to sandwich both sides of the web in the traveling direction of the web, and the gas blowing out toward the web from the gas blowing nozzles causes A non-contact conveying device that conveys the web by continuously floating it in the direction of travel is commonly used (Special Publication No. 53-551, Japanese Patent Publication No. 53-551,
4-38525). The present applicant has published Japanese Patent Application Laid-Open No. 63-27360 as a non-contact conveying method for webs using this non-contact conveying device in terms of stabilization of floating and reduction of equipment and running costs.
Furthermore, in the non-contact conveyance method of the web, a web conveyance nozzle that can increase the flying height, prevent the web from fluttering, and stabilize the floating is disclosed in Japanese Patent Application No. 63-23259.
I applied for No. 2.

As shown in Fig. 4, static pressure support type gas blowing nozzles 2 are arranged at different positions so as to sandwich both sides of the web 1 in the traveling direction of the web 1, and the web 1 is floated in a continuous wave shape in the traveling direction. In the non-contact conveyance method for the web l, in which a convex portion 5 is provided between both green gas ejection slits 3 of the static pressure support type gas blow-off nozzle 2, the convex portion Wc in the web traveling direction of the convex portion is 30 to 70% of the distance W between the gas ejection slits 3 on the edge, and the rising height Hc from the ejection surface is 5 to 70%.
25■, the angle θ between the rising surface and the jetting surface is Z45゛ ~
Z135' is a web conveying nozzle characterized in that the length Lc in the direction of the web width is greater than or equal to the web width. [Problems to be Solved by the Invention] However, when the web is a buffy film (for example, the web is based on polyethylene terephthalate (PET) and
In the case of a thin film of ~20 II m or a thin film of 50 to 180 μm based on triacetyl cellulose (TAC), if an organic solvent is applied to the web, the web is swollen by the solvent, and the temperature is high. It becomes pia mater. ) During conveyance, a knick-like wrinkle may occur near the center of the web, which may cause the web to come into contact with the nozzle. The pressure distribution between the web and the nozzle in the web width direction is high at the center of the web and low at both ends (almost most of the gas flows out of the system from both ends).

When the web is a soft coat, the web undergoes deformation in the width direction of the web in accordance with this pressure distribution. This appears as a change in the flying height in the width direction of the web. That is, in the web above the upward gas blowing nozzle, a convex pattern deformation occurs in the width direction. On the other hand, a similar change occurs in the web with the downward gas blowing nozzle.1 At this time, a downward convex pattern deformation occurs in the width direction. In other words, an upwardly convex deformation and a downwardly convex deformation occur adjacent to each other in the floating web, and an unreasonable deformation occurs in the continuous portion of the two. At this time, a knick-like wrinkle occurs in the center of the web in the width direction, and there is a high possibility that the web will come into contact with the gas blowing nozzle, resulting in failure. In addition, these scratch-like wrinkles may remain in the final product, resulting in quality defects. This phenomenon cannot be solved by increasing the airflow. If the air volume is increased, the pressure distribution between the web and the nozzle in the width direction becomes higher at the center, and therefore the flying state of the web becomes convex, causing even larger knick-like wrinkles to occur on the web.

The object of the present invention is to solve the above-mentioned problems, and to provide a stable system that enables the production of high-quality products without the risk of knick-like wrinkle failure or contact between the web and the gas blowing nozzle even in extremely soft webs. The purpose of this invention is to provide a contactless web conveyance device. [Means and actions for solving the problem]
The above objects of the present invention are (1) static pressure support type gas blowing nozzles having one gas blowing slit on each edge are arranged alternately in the web traveling direction and on both sides of the web to advance the web. In a non-contact conveying device for a web that floats and conveys a web in a continuous wave pattern, one of the two gas blowing slints of the gas blowing nozzle is closed at the center in the width direction of the web. A non-contact web conveyance device featuring: (2) The non-contact conveyance device for a web according to claim (1), characterized in that one of the gas jetting slits is closed by 5 to 25% of the width of the web at the center of the web in the web direction. .

It is achieved by To explain the present invention using the drawings, a web floated by a static pressure type gas blowing nozzle has a pressure distribution between the web and the nozzle in the width direction as shown in FIG. 2(a). That is, the pressure is maximum at the center of the web, and O (atmospheric pressure) at the side edges of the web. At this time, if the web is thin or has a high temperature and has extremely low web rigidity, the web deforms according to the pressure distribution described above. (At this time, the pressure distribution is absorbed by the deformation of the web and becomes fairly uniform in the width direction).

When nozzles are placed alternately and consecutively above and below the web, the web will be deformed so that it is convex upward when floating on the nozzle facing upward, and convex downward when floating on the nozzle facing downward. ．． At this time, the deformation of the web becomes difficult at the continuous portion of the upwardly convex and downwardly convex portions, and a knick-like wrinkle occurs in the center of the web in the width direction. These knick-like wrinkles do not occur at an intermediate point in the upwardly convex and downwardly convex web transport directions, but rather occur in the vicinity of the downwardly directed gas blowing nozzle.

This is due to the following reasons. In the case of a downward nozzle, the weight of the web does not act against the nozzle side. Therefore, the pressure between the web and the nozzle is smaller than in the case of an upward nozzle. As a result,
The tendency for convexity is smaller for downward nozzles than for upward nozzles. As a result, the wrinkles that appear on the web occur in the vicinity of the downward nozzle that moves from the upward nozzle to the downward nozzle. There are two possible countermeasures: making the widthwise pressure distribution uniform between the web and nozzle, or increasing the flying height of the knick-like wrinkles with a downward-facing nozzle to reduce contact with the nozzle. Increasing the overall air volume with downward facing nozzles will strongly shape the pressure distribution between the web and the nozzles in the web width direction. In addition, increasing the air volume only at the wrinkled part can prevent wrinkles,
Although this method is effective in preventing nozzle contact, it is difficult in practice because it is impossible to predict the location where the wrinkles will occur, and the method of increasing air volume is undesirable in terms of energy costs.

The most effective countermeasure is to make the pressure distribution between the web and nozzle uniform in the width direction. At this time, it is effective to reduce the amount of gas ejected at the center of the web, but reducing the amount of air at the center for both the two slits of the nozzle means that the nozzle and web This tends to cause a sudden drop in the pressure between the two, and even slight changes or fluctuations in conditions can make it easier for the center to come into contact. There is also a high possibility that uneven drying will occur in the center. Of the two gas ejection slits on both edges of the gas ejection nozzle, a wind shield plate is provided in the center of only one of the gas ejection slits in the width direction of the web.
Uniform pressure distribution between the webs and stability against condition changes and fluctuations can be achieved.

Figure 1 shows an embodiment of the gas blowing nozzle of the present invention having a wind shield plate in the center of the web in the width direction. In FIG. 1(a), a web 1 is floated in a wave-like manner by gas blowing nozzles 2 which are alternately arranged above and below with the web 1 in between. Each gas blowing nozzle 2 has two gas blowing slits 3 on both edges.
has.

A wind shielding plate 4 is provided at the center of one of the two gas ejection slits in the web width direction in order to equalize the pressure distribution between the nozzle webs in the web width direction.

As shown in Figure 1), the wind shield tllj4 is constructed of a thick plate on the gas ejection surface of the gas ejection nozzle 2 so as to cover the gas ejection slit 3. The wind shield plate 4 may be provided at the same height as the gas ejection surface or inside the gas ejection slit, or one slit may be provided from the beginning at the center in the width direction of the web as shown in FIG. Although it is possible to use a material without slits, it is more stable in terms of levitation if the slit is covered by a plate with a thickness that is convex from the gas ejection surface. This is because when the gas existing between the gas blowing nozzle and the web flows out from the wind shield by providing a wind shield over the gas jet slit, negative pressure is generated on the wind shield.
The web may be sucked in and the flying height of the web may decrease, but if the wind shield is thick, the outflowing gas will be temporarily blocked by the wind shield, and an airflow will be generated from the nozzle toward the web, causing it to float. This is thought to be because the decrease in volume is suppressed and the levitation becomes more stable. The thickness of the wind shield plate is preferably 3 to 15 mm, more preferably 5 to 10 mm. If it is too thick, the wind shield and web will come into contact. Also, the wind shield plate does not have to block the wind 100%. It would be good if it could block most of the wind. Therefore, a porous material can also be used as the wind shield.

Furthermore, it is not necessary to provide wind shields to all gas blowing nozzles. It is sufficient to perform the process on an upward gas blowing nozzle where the weight of the web acts and the pressure distribution between the nozzle and the web becomes more convex.

In the present invention, the web refers to paper, plastic film,
Contains resin-coated paper, Hewei paper, etc. The material of the plastic film is, for example, polyolefin such as polyethylene, polypropylene, polyvinyl acetate, polyvinyl chloride; vinyl polymer such as polystyrene; 6.6
-Nylon. 6-Boria such as nylon, polyethylene terephthalate. Polyester such as polyethylene-2,6-naphthalate, polycarbonate. Cellulose triacetate. Cellulose acetates such as cellulose diacetate are used. Further, the resin used for resin-coated paper is typically polyolefin such as polyethylene, but it is not necessarily limited to this. Web thickness is 10μm to 300μm
Applies to a maximum temperature of 160°C within the range of 160°C. [Embodiment] An embodiment of the gas blowing nozzle used in the non-contact web conveying device of the present invention will be described with reference to FIG.・Convergence of web 1: 1000cm ・Thickness of web 1: 100lIm ・Material of web 1: Cellulose triacetate ・Wind shield length L
100 ■ - Height of the wind shield H: 5 - Width of the wind shield W: 50 ■ - Gas blowout slit width: 4 cabinets - Web temperature: 100°C This allows the gap between the nozzle and the web in the upward gas blowing nozzle in the web width direction. The pressure distribution is shown in Figure 2 (
(al to medium), the occurrence of wrinkles disappeared, and failures caused by contact between the nozzle and the web and deformation of wrinkles were also resolved. Also, uneven drying of the web did not become a problem at this time. The size of the windshield plate 4 is important.
If it is small, the effect is insufficient, and if it is large, the flying height at the center becomes small, making it easier for the nozzle and the web to come into contact. Furthermore, when transporting multiple types of webs, the size of this temporary wind shield is also important. For webs with thin pia coat and low stiffness, the size of the wind shield that is sufficiently effective is a web with higher rigidity, a nearly uniform floating pattern in the width direction, and less convex deformation in the width direction. On the contrary, the effect is too great, and there is a possibility of contact with the wind shield. In other words, the size of the wind shield must be determined with due care, not only in terms of effectiveness and stability for a single type of web, but especially when using multiple types of webs. Although there is a method of changing the size of the wind shield depending on the type of web, this method is inefficient and requires complicated and expensive equipment, which is not desirable. As a result of conducting experimental analyzes and evaluations under the above conditions, it was found that the size of the wind shield plate is preferably in the range of 5 to 25% of the web width. [Effects of the Invention] By using the web flotation nozzle of the present invention, (1) Even webs with extremely low rigidity due to thinness or high temperature can be stably floated and conveyed without worrying about contact with the nozzle. It's now possible.

(2) It was possible to prevent the aforementioned knick-like wrinkles that may occur during conveyance of the web, and to prevent web failure (residual deformation) caused by this. The above improvements improved the quality of the product, which made it possible to speed up the coating process and also contributed to cost reduction.

[Brief explanation of drawings]

Figure 1 shows a layout diagram (a) and a perspective view (c) of the gas blowing nozzle of the non-contact conveying device of the present invention, and Figure 2 shows a draft of the pressure distribution diagram between the web and the nozzle in the web width direction. Before installation (a) and after installation of the windshield plate (b), FIG. 3 is a perspective view with one slit discontinuous among the two slits on the gas jet nozzle used in the present invention, and FIG. 4 is a perspective view of a conventional gas blowing nozzle for increasing flying height, preventing web flapping, and stabilizing flying. l... Web 3... Gas blowing slit 4... Wind shielding part convex part 5... Convex part (3 idiots) 2... Gas blowing nozzle

Claims (2)

[Claims] (1) Static pressure support type gas blowing nozzles having one gas blowing slit on each edge are arranged alternately in the web traveling direction and on both sides of the web, so that the web is formed in a continuous wave shape in the traveling direction. A non-contact conveying device for a web that is conveyed by floating, characterized in that one of the two gas blowing slits of the gas blowing nozzle is closed at the center in the width direction of the web. Contact conveyance device. (2) The non-contact conveyance device for a web according to claim 1, wherein one of the gas ejection slits is closed by 5 to 25% of the width of the web at a central portion in the width direction of the web.