JPH11104552A - Heat treatment of long-sized web - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a sufficient heating effect without spending the time for heating down to the central part of winding by forming a winding body provided with spacings without the insertion of spaces between the webs of respective turns and subjecting the formed winding body to a heat treatment. SOLUTION: At the time of winding the long-sized web 3 on a core 1, the winding speed of the long-sized web 3 by the core 1 is made smaller than the supply rate of the long-sized web 3 to the core 1, by which the winding body is formed. For example, the long-sized web 3 may be formed by winding the long-sized web 3 on the core 1 at a speed smaller than the leading out speed of the long-sized web 3 from the tail of the coating and predrying stage of the long-sized web 3. The winding body provided with such spacings 2 is then heat treated. The rolled object free of the spacings 2 may be obtd. by rewinding at the time of product inspection after the heat treatment or winding up to the disappearance of the spacings 2 while applying tension to the terminal of the long-sized web 3, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat treatment process for a long web, and more particularly to a process and a technology for heat-treating a long web in a wound state.

[0002]

2. Description of the Related Art Conventionally, image recording media such as thermosensitive coloring films and photographic materials, magnetic recording materials and the like can be obtained by applying and drying a coating solution on a long film. In the manufacturing process of such a product, a heat treatment process may be provided after the coating and drying process. Its purpose is several. For example, removal of residual moisture and residual solvent from a coating film, or annealing, aging treatment, annealing treatment, and crosslinking promotion of a polymer material such as a coating binder can be mentioned. Such a process often requires a relatively long time to obtain a predetermined effect. Therefore, if a system in which the long web is continuously transported from the coating and drying process to the heat treatment process is used, the apparatus becomes extremely large. Alternatively, if the size of the apparatus is set to an appropriate size, the processing speed per hour becomes extremely low. From such a thing,
After winding the long web, it is practical and often the case to be heat-treated.

[0003] US Pat. No. 1,651,744 has proposed a device for processing a long web as it is wound. According to this method, the left and right ends of the web are subjected to a knurling process, so that a gap is provided between the webs at the time of winding, so that the heat treatment can be performed without the surface being in contact. However, in this method, since the gap is formed by deforming the web, the gap to be formed is limited to at most several tens of microns, and in the case of a wide web, there is a case where the web is partially contacted in the width direction. In some cases, a still unstable film after film formation may lead to adhesion between webs and generation of scratches due to the contact between the front and back surfaces of some webs as described above. Furthermore, in such a narrow gap, even if the effect is such that the web is not brought into contact, if the purpose of the heat treatment is to remove water or a solvent, the gap is narrow, so that the moisture or the solvent goes out of the winding. The passage is not secured and does not provide sufficient effects. In addition, since this method deforms the end face of the web, the deformation extends to the central portion, and the product portion is slightly affected.

Further, when winding a long web, the distortion may be accumulated little by little, and the winding itself may be greatly deformed. For these reasons, JP-B-47-16064 and JP-B-54-74862 have devised methods for minimizing the deformation of the end face. Also, Japanese Patent Publication No. Hei 5-19899,
JP-A-7-195551 and JP-A-8-220
Japanese Unexamined Patent Publication No. 694 proposes that a large gap is provided on the end face of the web, such as by applying a spacer or an adhesive. However, even when such a method is used to process a long web, problems such as deformation of the winding cannot be solved.

[0005] Therefore, the problems of efficient heat treatment of a conventional long web in a rolled state can be summarized as follows: (1) The voids that can be formed are small;
When the purpose of the heat treatment is drying, the effect of the heat treatment is not sufficient. (2) Since the gap is small, it takes time to heat up to the center of the winding. (3) The gap is small, and Since the heat treatment is performed in a stationary state, partial contact, fusion and damage may occur, and (4) the outer shape of the winding (the outer shape of the roll) may be deformed.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks and to heat up a central portion of a long web when the long web is efficiently heat-treated in a rolled state. Time is not required, sufficient heat treatment effect is obtained, the web surfaces are partially in contact with each other, there is no fusing or damage, and the winding outer shape (roll outer shape) is not deformed, Another object of the present invention is to provide a method for easily forming a long winding.

[0007]

SUMMARY OF THE INVENTION The object of the present invention is to provide a method for heat treating a wound body obtained by winding a long web around a winding core according to the present invention. A heat treatment method for a long web, wherein a wound body having a gap is formed without inserting a web, and the formed wound body is heat-treated. The method according to the above item (1), wherein the long web is formed by winding the long web around the winding core at a speed smaller than a speed at which the long web is taken out from the end of the pre-drying step. Heat treatment method for a long web ", (3)" wherein the heat treatment is performed by rotating a winding core of the winding body during the heat treatment and moving a portion of the gap of the web of the winding body. Heat treatment of the long web according to the item (1) or (2). Method, (4) "a method for heat treating a long web according to the above (3), characterized in that the rotation direction is reversed", (5) "supplying an air flow from the end face of the wound body. (1), (2)
Item, the method for heat treating a long web according to any one of the items (3) and (4) ”, (6)“ the supercritical carbon dioxide is present during the heat treatment ”. (1)
, (2), (3) or (4).

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings. FIG. 1 shows an outline of an example of a wound body used in the heat treatment method of the present invention. In FIG. 1, (1) is a core for winding a long web. (2) is a long web. (3) is the formed gap. When the long web (2) is wound around the core (1), the winding speed of the long web (2) by the core (1) is set to be long. It can be easily formed by making the speed of feeding the web (2) to the core (1) smaller than the feeding speed of the web from the end of the coating and pre-drying process of the web. It can be easily formed by winding the long web around the winding core at a low speed. And such a winding body with a gap,
After the heat treatment, the roll can be easily formed into a gap-free roll by rewinding at the time of product inspection, or winding up tightly while removing tension while applying tension to the end of the web.

In the heat treatment method of the present invention, an air flow can be supplied from the end face of the winding body to positively replace air flowing in the gap between the webs. In addition, the present heat treatment method can be combined with another method, for example,
The present invention can be applied to a supercritical extraction method that has a great effect on solvent removal. The supercritical extraction method will be briefly described by taking as an example a case where carbon dioxide is used as a commonly used extractant. Carbon dioxide is in a gaseous state at normal temperature and normal pressure, but at a temperature and pressure above the critical point (31.1 ° C., 7.38 MPa), it becomes a supercritical fluid that is neither gas nor liquid. Since carbon dioxide in a supercritical state shows solubility in various substances due to changes in temperature and pressure, it is possible to extract a target substance by using this solubility. An example of applying supercritical extraction to the removal of substances is Masuoka et al.'S removal of residual solvent in polymer resins (Chemical Engineering Transactions, 1
6, 1020 (1990)). When supercritical carbon dioxide is used as the extractant, the extract is a solvent, and the extraction is rapid, and the removal of the extractant dissolved in the polymer resin is faster than when using other extractants. Is very easy.

Further, the heat treatment method of the present invention is applied to
It can also be combined with the solvent removal promoting method devised by As et al. A brief description of the method of promoting solvent removal by Vrentas et al. Vrentas et al. App. P
Olly Sci, 30, 4499 (1985) proposes a method of introducing a second solvent in order to promote the removal of the solvent from the coating film. This method is intended to remove a small amount of a high-boiling solvent remaining in a polymer resin at a relatively low temperature. Factors that make it difficult to remove the high-boiling solvent remaining in the polymer resin are mainly the following two points. (1) As the amount of solvent remaining in the polymer resin decreases, the diffusion coefficient of the solvent in the polymer resin sharply decreases. (2) The diffusion coefficient of the solvent in the polymer resin decreases as the size (molecular volume) of the molecules of the solvent itself increases (the high-boiling point solvent has a relatively large molecule and therefore a small diffusion coefficient).

[0011] The method of Vrentas et al. Is directed to a polymer resin film in which a very small amount of a high boiling solvent (first solvent) remains.
The following processing is performed. The substrate is exposed to and heated in a second solvent vapor having a smaller molecular volume than the high boiling point solvent. Remove from the second solvent vapor atmosphere and heat. Is to introduce a second solvent into the system. Thereby, the diffusion coefficient of the solvent (both the first solvent and the second solvent) in the resin film is increased, and the first solvent that is difficult to remove is replaced with the second solvent. The operation of removing the second solvent remaining in the resin film. According to Vrentas et al., The removal time of the solvent is shorter than the time required for simply removing the first solvent remaining in the polymer resin by simply heating the first solvent. Things. Therefore, the method of Vrentas is substantially an operation of heating in a solvent vapor.

[0012]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. Example 1 A long web before heat treatment is described. PET
(Polyethylene terephthalate) Film (thickness: 50 μm, width: 250 mm) is coated with a coating liquid A mainly containing polyvinyl chloride-vinyl acetate copolymer resin by a wire bar coater and dried.
g / m ^2, and the drying was performed in a drying box (2 m) in which nozzles having a slit width of 4 mm were arranged vertically at a pitch of 250 mm. The nozzle wind speed at this time is 15m
/ S at a temperature of 60 ° C. for 2 minutes (coating speed is 1 m /
min). As described above, a long web before heat treatment was prepared. Coating liquid A PVC-vinyl acetate copolymer resin 18 parts by weight (Union carbide VYNS-3) Methyl ethyl ketone 62 parts by weight Toluene 20 parts by weight A long web before heat treatment is made into a core (paper, 3 inch inside diameter, wall thickness 11 mm) ) To form a roll so that the gap between the webs is about 1 mm. The length of the wound web was about 100 m. This was heat-treated for 24 hours in a 60 ° C. hot air circulation dryer. Meanwhile, the winding core was rotated. The rotation speed at this time was 3 rpm.

Example 2 Hot air heated to 60 ° C. by a hot air generator (TSK-20 manufactured by Taketsuna Seisakusho) was applied to the end face of the wound body prepared in the same manner as in Example 1. Hot air was supplied uniformly to the end surface of the winding body, and the wind speed was 5 m / s at the winding end surface.

Example 3 The width of a long web prepared in the same manner as in Example 1 was 100
mm. This was wound around a core (made of aluminum, inner diameter 20 mm, wall thickness 2 mm), and a wound body was prepared in the same manner as in Example 1 so that the gap between the webs was about 1 mm. The length of the wound web was about 12 mm. This wound body is placed in a cylindrical pressure vessel (inner diameter 150 m).
m). Fix the end of the core to the bottom of the pressure vessel, cover it and compress carbon dioxide to 100 atm.
The pressure vessel was sealed and immersed in a water bath at 40 ° C. for 10 minutes so that the cylindrical side surface was substantially horizontal. During this time,
The pressure vessel was alternately rotated three times on each side. afterwards,
The pressure vessel was taken out and the pressure was released.

Comparative Example A tape having a width of 12 mm (Scotch Mending Tape 810-1-12) attached to both ends in the width direction of a long web before heat treatment prepared in the same manner as in Example 1 was wound around a core. Example 1 except that the winding was stopped all the time
The heat treatment was performed under the same conditions as described above.

Evaluation The evaluation of the wound body after the heat treatment was made based on whether there was a scratch on the surface of the coating film or whether there was any evidence that the web was bonded to the web. The effect of the heat treatment was performed by comparing the residual solvent amount of the coating film before the heat treatment with the residual solvent amount after the treatment. For the evaluation of the residual solvent, a part of the coating film was sampled, and its weight was measured with a precision electronic balance. Next, this sample was wrapped in Pyrofoil f358 (manufactured by Nippon Kagaku Kogyo) and heated with a Curie Point Pyrolyzer JHP-3 (manufactured by Nippon Kagaku Kogyo) for 15 seconds to evaporate the contained solvent. This was introduced into a gas chroma HP5980II (manufactured by Yokokawa Analytical Systems) to obtain chromatography.
The residual solvent amount was calculated from the chromatography.

Evaluation Results Table 1 summarizes the evaluation results. As shown in Table 1, in each of the examples, there was no adhesion between the front and back of the web, and the residual solvent concentration as a result of the heat treatment showed a low value irrespective of the position in the winding, while the comparative example Although there was some adhesion and the amount of the residual solvent was low to some extent near the outside, there was almost no change from the beginning when approaching the core.

[0018]

[Table 1]

[0019]

As is apparent from the detailed and specific description above, according to the method for winding a long web of the present invention, no special processing is applied to the end face in the width direction of the web, so that The central part is not deformed under the influence.
Also, instead of increasing the thickness of the web end surface and leaving a gap, it is easy to widen the gap because the winding method is devised, and the first winding is slightly larger than the circumference of the core with respect to the winding core. By wrapping the long web loosely, the second wrapping the web slightly longer than the first wrap, and then winding in this way, the long web takes the form as shown in FIG. If
At least the web at the bottom of the winding core can maintain a gap without the front and back contacting each other, and since the gap to be formed is sufficiently wide, when the purpose of the heat treatment is to remove moisture or a solvent, Can achieve high removal efficiency. This is for the following reasons. The effect of removing water and solvent has a close relationship with the size of the formed gap.
This relationship is particularly important when the width of the web is wide.Water or solvent molecules discharged from the web in the gaseous phase at the center in the width direction of the web diffuse mainly through the gaps in the width direction to be wound up. It diffuses out from the end face. At this time, a narrow gap means that a passage for diffusion is narrow, and the water or solvent removal rate becomes slow. Further, in some cases, once vaporized, it may be recondensed in a part of the width direction. In such a case, traces may be left on the web surface after condensation, but according to the present invention, such inconvenience can be avoided. When heating a winding without a gap, heat is mainly transmitted by heat conduction from the outer surface of the winding, whereas in the case of the present invention, the gap between each web of the winding body is sufficiently large, Since air can flow through the gap, there is an effect of convective heat transfer in addition to heat conduction, and the temperature distribution in the winding is reduced with an increase in heat transfer speed.

On the other hand, the portion of the web above the winding core where the weight of the web is applied comes into contact with the front and back of the web. If heat treatment is performed for a long period of time without this, the original effect may not be obtained in this portion. In the invention, the position of the upper part of the core can be updated by rotating the core, and in many cases, short-time contact between the front and back of the web does not become a problem. Can be obtained.

Further, when performing the heat treatment after the completion of the winding, the rotation direction of the winding core may be one direction, but if the rotation is performed in one direction for a long time, the winding may be loosened. This can be prevented by periodically reversing the rotation direction of the winding. Still further, according to the present invention, since the gap between the web is sufficiently large, it is possible to apply an airflow from the winding end face, and to allow the airflow from the end face to flow through the gap, to remove water and solvent, The effect of keeping the temperature distribution of the entire winding uniform can be further ensured.

The supercritical extraction method is effective for removing the solvent. However, even if the winding without gaps is subjected to the supercritical treatment, the supercritical fluid cannot enter the inside of the winding. Although it was effective only in the portion close to the end face of the winding, when the heat treatment method of the present invention was combined with the supercritical extraction method, a large gap was taken, so that the flow of the supercritical fluid was smooth and the solvent removal was large. The effect can be expected.

Further, in order to realize the solvent removal accelerating method of Vrentas et al., It is necessary to precisely control the amount of vapor in the vapor phase for heating the material to be dried. However, the web is continuously conveyed. In such a case, complicated equipment such as an inert dryer was required due to the explosiveness of the solvent vapor. The heat treatment method of the present invention
When combined with the solvent removal promotion method of rentas et al.
Since it can be operated in a closed system, complicated devices are not required.

In the usual heat treatment method for a roll of a long web, the winding core is rotated with a gap in the web during the heat treatment. Although wrinkles may be generated, it was confirmed that no wrinkles were generated when a PET film having a thickness of 50 μm or more was used as a substrate according to the method of the present invention.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a long web wound body of the present invention.

[Explanation of symbols]

 1 core 2 gap 3 web

Claims (5)

[Claims] 1. A method for heat-treating a wound body obtained by winding a long web around a winding core, wherein a wound body is provided with a gap without inserting a spacer between the webs of each round. And heat-treating the formed wound body. 2. The long structure according to claim 1, wherein the heat treatment is performed by rotating a take-up core of the take-up body during the heat treatment and moving a portion of the gap of a web of the take-up body. Web heat treatment method. 3. The method for heat treating a long web according to claim 2, wherein the rotation direction is reversed. 4. The heat treatment method for a long web according to claim 1, wherein an air flow is supplied from an end face of the winding body. 5. The method for heat treating a long web according to claim 1, wherein supercritical carbon dioxide is present during the heat treatment.