JP3714550B2 - Web or sheet drying equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a web or sheet drying apparatus, and in particular, when a web-like or sheet-like plastic film, paper, cloth (hereinafter referred to as “web”) is dried while being conveyed, the width direction of the web is a pin or a clip. It is related with the drying apparatus of the web or sheet | seat which dries while conveying the web stretched in the width direction by hold | maintaining with the holding means.
[0002]
[Prior art]
There is a solution film forming method as a method of forming a film by spreading a dope into a thin film. The web formed by the solution casting method contains a high-concentration solvent, and when the web is dried while being conveyed, the web generally shrinks as it is dried. In such web conveyance / drying, the widthwise direction of the web is stretched by holding the web by holding a plurality of holding means such as pins and clips at both side edges in the widthwise direction of the web. A drying apparatus that dries while being conveyed is known (Japanese Patent Publication No. 39-29211).
[0003]
The web drying apparatus can suppress the shrinkage of the web in the width direction due to heat during drying, and can prevent wrinkles due to the shrinkage from occurring on the dried web. Incidentally, the contraction of the web occurs not only in the width direction of the web but in all directions, but the transport tension acts in the transport direction of the web, and has an effect of suppressing the contraction. In this way, when the web is dried, it is transported using a web or sheet drying device, thereby ensuring the strength and flatness required for the dried web.
[0004]
[Problems to be solved by the invention]
Incidentally, the web is usually dried at a temperature of several tens of degrees C. to 100 degrees C. However, the temperature is further increased with the recent increase in the speed of conveyance. When the holding means such as the pin or clip is also heated by the increase in the drying temperature in this way, the temperature of the holding means becomes equal to or higher than the foaming temperature of the web, and the holding means is near the holding portion that holds the web. Foaming occurs on the web surface. When foaming occurs, the foamed web strongly adheres to the holding means, and it becomes difficult to remove the web from the holding means. Moreover, there is a problem that if the web is detached with a large force, the web breaks.
[0005]
Further, the web fixed to the holding means by foaming remains on the holding means even after the web is detached from the holding means. As a result, there is a problem that the web remaining on the holding means falls and contaminates the inside of the drying apparatus or makes it difficult to use the equipment.
[0006]
Furthermore, in the case of a web having a high solvent content before drying (for example, in the 70% range), when the web is bitten into the holding means, a thin film of the web is formed on the surface of the holding means, and this thin film holds the web. When it leaves the means, it generates dust and adheres to the surface of the web. Accordingly, there is a problem that the web becomes unusable as a product and product loss occurs. As a measure against this dust generation, it was also considered to provide a vacuum type dust removing device at the separation position where the web is detached from the holding means, but complete dust removal was difficult.
[0007]
Thus, the conventional web or sheet drying apparatus has not been sufficiently satisfactory for the user.
[0008]
The present invention has been made in view of such circumstances, and prevents foaming of the web when drying the web to improve the detachability of the web from the holding means, and also provides a high solvent content before drying. Even in such a case, an object of the present invention is to provide a web or sheet drying apparatus in which a web thin film is formed on the surface of the holding means and does not generate dust when the web is held by the holding means.
[0009]
[Means for solving the problems]
In order to achieve the above object, the present invention provides a drying apparatus for drying with a drier while holding and conveying both edges of the web with a clip or pin holding means, wherein the hot air of the drier is applied to both edges of the web. So that the width of the dryer is shorter than the width of the web, and a pair of coolers are provided in parallel on both sides of the dryer to blow cold air toward the holding means. Thus, cooling is performed so that the temperature of the holding means is lower than the foaming temperature of the web .
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of a web or sheet drying apparatus according to the present invention will be described in detail with reference to the accompanying drawings.
[0011]
FIG. 1 is an overall configuration diagram of a web or sheet (hereinafter simply referred to as “web”) drying apparatus according to the present invention, and FIG. 2 is a front sectional view of FIG. As shown in these drawings, the drying apparatus 10 of the present invention mainly uses a holding means 14 such as a pin or a clip (hereinafter referred to as an example of the pin 14) in the width direction of the web 12 formed by the solution casting method. And a drier 18 that heats the web 12 conveyed by the conveyer 16 by applying heat such as hot air or infrared rays (hereinafter, described with an example of hot air) and drying it. , And a cooler 20 that cools the pin 14.
[0012]
Here, the solution casting method is a method of casting a dope (a high-viscosity solution containing a solvent) on the surface of a band or drum to form a film-like web 12, and then peeling the web 12 from the surface of the band or drum. It is the method of forming into a film by taking. And the strength and flatness required for the web 12 can be secured by drying the web 12 before drying formed by the solution casting method.
[0013]
The conveyor 16 is suspended between a pair of drive pulleys 24 and 24 fitted to both ends of the rotary drive shaft 22 and a pair of driven pulleys 28 and 28 fitted to both ends of the rotary driven shaft 26. A pair of endless belts 30, 30, and pin plates 34, 34 supported by a plurality of support members 32, 32... Arranged in a line along the rotational direction of the endless belt 30. As shown in FIG. 3, a large number of pins 36, 36... Planted on the pin plate 34, and biting that bites the pins 36 into both side edges of the web 12 at the transfer start position of the web 12. It is comprised with the roller 38,38. Accordingly, the web 12 held by the pin 36 on the pin plate 34 is held in a state where the width direction is stretched, and the forward path of the conveyor 16 (endless in FIG. 1) is accompanied by the movement of the endless belt 30. The pin 36 is removed by the reversing operation of the pin plate 34 at the position of the drive pulley 24. After the web 12 is detached, the pin plate 34 moves on the return path of the conveyor (the lower portion of the endless belt 30 in FIG. 1), and is further reversed by the driven pulley 28 to return to the forward path.
[0014]
The dryer 18 includes an upper dryer 18A disposed above the web 12 conveyed on the forward path of the conveyor 16 and a lower dryer 18B disposed below the web 12. Hot air is blown onto both surfaces of the web 12. Further, the width of the dryer 18 is slightly shorter than the width of the web 12 so that the hot air from the dryer does not hit the side edges of the web 12.
[0015]
The cooler 20 is arranged in parallel with the upper dryer 18A on both sides of the upper dryer 18A arranged in the forward path of the conveyor 16 and cools the cooler 20 toward the pin plate 34 that holds both side edges of the web 12. A pair of blow-out type coolers 20A and 20A that are blown out, and a pair of duct-type coolers 20B that are arranged in the return path of the conveyor 16 and that cool the pins 36 by moving the pin plate 34 in a duct to which cold air is supplied, 20B. In the duct type cooler 20B, a long opening 40 is formed from one end to the other end along the longitudinal direction of the duct type cooler 20B on one side surface of the square tube shape, and the pin plate 34 passes through the opening 40. The duct type cooler 20B is moved.
[0016]
The blowout type cooler 20 </ b> A cools the web 12 so that the temperature of the pins 36 of the pin plate 34 is maintained below the foaming temperature of the web 12 while the web 12 is being dried by the dryer 18. FIG. 4 is a relationship diagram of the solvent content of the web 12 before drying and the foaming temperature of the web 12. The higher the solvent content, the lower the foaming temperature of the web 12.
[0017]
On the other hand, the duct type cooler 20B cools so that the temperature of the pin 36 when the web 12 is bited into the pin 36 by the biting roller 38 is equal to or lower than the gelation temperature of the dope + 15 ° C.
[0018]
Next, the operation of the web or sheet drying apparatus configured as described above will be described using an example in which a web having a solvent content of 70% before drying is dried to a solvent content of 10%.
[0019]
The web 12 before drying formed by the solution casting method is held by the both-side edges of the web 12 being bitten into the pins 36 by the biting rollers 38 arranged at the drying start position. Thereby, the web 12 is conveyed in a state where both side edges thereof are stretched. The web 12 before drying, whose both edges are held by the pins 36, is dried by blowing high-temperature drying air from above and below the web 12 by the upper dryer 18A and the lower dryer 18B. When the web 12 is dried, the web 12 between the pin plates 34 is dried with both side edges held by the pins 36, so that the strong contraction force generated by the drying tightly tightens the pins. It becomes a state. As a result, since the internal pressure for causing foaming in the web 12 becomes larger, foaming is suppressed and foaming does not occur at the foaming temperature shown in FIG. However, the web 12 of the pin 36 portion, which is both side edges of the web 12, is a free end where the end of the web 12 is not held at all, and the shrinkage force caused by drying is reduced, so foaming is performed at the foaming temperature shown in FIG. Resulting in. When the web 12 is foamed, the web 12 is firmly fixed to the pin 36, and the web 12 cannot be easily detached from the pin 36. Further, if the web 12 is forcibly detached from the pin 36 with a large force, the web 12 is broken at the time of separation. In addition, the fragments of the web 12 remaining on the pins 36 after falling off may contaminate the inside of the drying apparatus or make it difficult to use the apparatus. For this reason, it is necessary to intensively cool the pin 36 portion.
[0020]
Therefore, according to the web or sheet drying apparatus of the present invention, during the drying of the web 12, the temperature of the pins 36 that hold both side edges of the web 12 is blown out from the blow-out type cooler 20A toward the pin plate 34. It was made to maintain below the foaming temperature of the web 12 by the cold air which is. Thereby, it can prevent that foaming arises on the web 12 surface of the pin 36 part. When the drying air temperature of the web 12 is not so high, vertical wind shields are provided at both side edge portions of the web 12 in place of the blowout type cooler 20A so that the high temperature drying air is applied to the pins 36. There is a way to avoid direct hits.
[0021]
Further, when the web 12 having a high solvent content before drying of 70% is entrapped into the pin 36 by the entrapping roller 38, a thin film of the web 12 is formed on the surface of the pin 36, and this thin film forms the web 12. When it separates from the pin 36, it generates dust and adheres to the surface of the web 12. As a result, the flatness of the surface of the web 12 is impaired, so that there is a problem that the web 12 becomes unusable as a product and product loss occurs. As a result of earnestly examining the solution of this problem by experiments or the like, the present inventor has obtained the knowledge that the temperature of the pin 36 immediately before it bites into the web 12 must be determined based on the gelation temperature of the dope. . That is, in the solution casting method, the dope cooled on the surface of the drum below the gelling temperature of the dope becomes a web 12 having a strength capable of forming a film by gelling, but the temperature of the pin 36 that bites into the web 12. If the temperature is higher than the gelation temperature of the dope, the gelation of the web 12 in the pin 36 portion is loosened and becomes liquid. As a result, it was found that the web 12 adhered to the pin 36 as a thin film. From this, it is ideal that the temperature of the pin 36 immediately before biting into the web 12 is equal to or lower than the gelation temperature of the dope, but actually, the dope at the time of biting is slightly in the state of the web 12. Since the drying of is progressing, it may be slightly higher than the gelation temperature of the dope. From the results of many tests, it was found from the results of many tests that when the temperature is up to the gelation temperature + 15 ° C., the web 12 does not adhere to the pin 36 as a thin film when the web 12 is bitten. Therefore, in the case of the present embodiment, since the gelation temperature of the dope is 5 ° C., the temperature of the pin 36 just before biting into the web 12 may be set to 20 ° C. or less.
[0022]
Therefore, according to the web or sheet drying apparatus of the present invention, the duct type cooler 20B is provided in the return path of the conveyor 16 after the web 12 is detached from the pin 36, and the pin plate 34 is disposed in the duct type cooler 20B. It was made possible to cool so that the pin temperature was 20 ° C. or lower during the movement. As a result, even when the web 12 before drying has a high solvent content, when the web 12 is bitten into the pin 36 by the biting roller 38, the thin film of the web 12 is formed on the surface of the pin 36. Can be prevented.
[0023]
In the present embodiment, the duct type cooler 20B is used for cooling the pins 36 in the return path of the transport conveyor 16, but a volatile liquid is sprayed and applied to the pins 36 as shown in FIG. And the cooler 21B using the evaporation soot may be used. In the present embodiment, the cooling of the pin 36 in the duct type cooler 20B is set to 20 ° C. or less. However, the gelation temperature of the dope varies depending on the dope prescription, and accordingly the pin 36 at the time of biting It is also necessary to change the cooling temperature. In the present embodiment, the pin 36 is described as an example of the holding unit, but the same applies to the case of a clip.
[0024]
【Example】
Hereinafter, examples carried out using the web or sheet drying apparatus described in this embodiment will be described.
[0025]
The dope composition, web drying conditions, pin cooling conditions, and the like in this example are as follows.
(1) Dope composition: for 100 parts of cellulose triacetate,
Triphenyl phosphate 15 parts Methylene chloride 290 parts Methanol 40 parts Butanol 20 parts
(2) Web types: Cellulose acetate film for photographic film
(3) Film formation of the web: A dope having the above composition was cast on a cooling drum to form a film-like web, and then the web was peeled off from the cooling drum to form a film. Dry with the web or sheet dryer of the invention.
(4) The solvent content of the web before drying: 73% (weight percent by weight)
(5) The solvent content of the web after drying ... 8% (wet basis weight%)
(6) Dry air temperature: 80 ° C to 100 ° C
(7) Cooling air temperature of the blowout type cooler: 0 ° C to 20 ° C (set to be below the foaming temperature in Fig. 4)
(8) Cold air temperature in the duct type cooler: -5 ° C to 0 ° C
As a comparative example, a conventional web or sheet drying apparatus without a blowout type cooler and a duct type cooler was used.
[0026]
As a result, when using the web or sheet drying apparatus of the present invention,
(1) During the drying of the web, there was no foaming of the web at the pin portion, and it was very easy to remove the web from the pin, and the web did not break.
{Circle around (2)} When the pin is engulfed in the web, the web thin film does not adhere to the pin, so there is no dust generation at the time of detachment and no problems such as product loss occur.
(3) Since the thin film of the web did not adhere to the pin, the pin was not soiled, and the drying apparatus could be used for a long time in a stable state.
[0027]
On the other hand, when using a conventional web or sheet drying device,
(1) During the drying of the web, foaming of the web occurred in the vicinity of the pin, and it was difficult to remove the web from the pin.
{Circle around (2)} Further, the force required for the separation is about three times that in the case of this embodiment, and the web may break due to an excessive separation force.
(3) When a pin is engulfed in the web, a thin film of the web adheres to the pin, and when it is detached, the thin film is generated as dust and adheres to the web surface, which causes a product loss.
{Circle around (4)} The web pieces and thin films fixed to the pins at the time of detachment tend to fall into the drying device and contaminate the drying device, and the drying device needs to be cleaned regularly.
[0028]
【The invention's effect】
As described above, according to the web or sheet drying apparatus of the present invention, since the holding means does not become hot with the drying heat during the drying of the web, there is no foaming of the web at the holding means portion during the web drying, When the web is held by the holding means, the web thin film does not adhere to the holding means.
[0029]
Thereby, since the web does not foam during drying, the web is not firmly fixed to the pin. Therefore, the web is easily detached from the pin, and the web is not broken.
[0030]
Further, since the thin film of the web does not adhere to the holding means, the thin film is generated at the time of separation and adheres to the web surface, which does not cause a product loss. Furthermore, since the holding means is not soiled by the adhesion of the thin film, the drying apparatus can be used for a long time in a stable state.
[Brief description of the drawings]
FIG. 1 is a side view of a web or sheet drying apparatus of the present invention. FIG. 2 is a front sectional view of a web or sheet drying apparatus of the present invention. FIG. 4 is a diagram illustrating the relationship between the solvent content of the web before drying and the foaming temperature of the web. FIG. 5 is a diagram illustrating the web of the present invention. Front sectional view for explaining another embodiment of sheet drying apparatus
DESCRIPTION OF SYMBOLS 10 ... Drying device, 12 ... Web, 16 ... Conveyor, 18A ... Upper dryer, 18B ... Lower dryer, 20A ... Blow type cooler, 20B ... Duct type cooler, 24 ... Drive pulley, 28 ... Drive pulley , 30 ... endless belt, 34 ... pin plate, 36 ... pin, 38 ... bite roller

Claims (3)

In a drying device that dries in a dryer while holding and conveying both edges of the web with a clip or pin holding means,
The dryer has a width shorter than the width of the web so that hot air from the dryer does not hit both edges of the web, and a pair of coolers are provided in parallel on both sides of the dryer. The drying device is characterized in that cooling is performed so that the temperature of the holding means becomes lower than the foaming temperature of the web by blowing cool air toward the holding means .   2. A drying apparatus according to claim 1, wherein the web is cellulose triacetate.   The drying apparatus according to claim 1 or 2, wherein the temperature of the hot air is 80 to 100 ° C.

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