JPH0852405A - Drying unit and coater - Google Patents

Abstract

PURPOSE:To obtain high-quality printed matter and coated material by matting the surface of the guide roller of a drying unit. CONSTITUTION:The surface of a metallic guide roller 2 is sandblasted or a layer of other materials is provided and matted to form a surface layer 9. A substrate sheet 6 mounted in a printing machine is delivered, sent into a printing unit, passed between a printing plate 5 and a presser drum and introduced into a drying unit 1 and guided by the guide roller 2 to be dried. Since the surface layer 9 of the roller 2 is matted, a way of escape for air is formed. Accordingly, unnuniform contact with the roller 2 caused by the corrugation of the sheet 6 due to the occlusion of air, etc., is prevented, and the adhesion state is stabilized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drying unit and a coating device. In particular, the present invention relates to a drying unit and a coating device which are extremely useful when performing printing and coating to form a film having uniform physical properties on a thin substrate.

[0002]

2. Description of the Related Art Conventionally, inks and coating liquids that are printed or coated on a substrate such as paper or plastic film in a coating device such as a gravure printing machine contain an organic solvent or a solvent such as water. As a drying unit used for drying this to obtain a dry coating film on a substrate, a hot air drying type drying unit is mainly used.

In this hot air drying type drying unit, various measures are taken to improve the drying efficiency because it is necessary to minimize the residual solvent in the coating so that the physical properties of the coating on the substrate are stable. ing. For example, dividing the drying unit into multiple zones, in order to prevent a large amount of solvent from boiling and forming bubbles in the coating at the beginning of drying, the drying temperature is lowered and the air volume is increased, and in the latter stage of drying the coating is dried. The drying temperature is raised and the air volume is lowered in order to drive out the solvent that is slightly left inside. In practical use, it is necessary to take into account conditions such as wanting to increase printing speed to improve productivity, and reducing the size of the drying unit due to restrictions such as machine installation conditions. In order to reduce the residual solvent in the coating at high speed, the drying temperature is set as high as possible.

[0004]

However, under a dry condition with hot air at a high temperature, and particularly when a thin substrate is printed / coated, a dried film having uniform physical properties is obtained. That was extremely difficult. For example, comparing a printing / coating product manufactured under conditions of high temperature and short drying time with a printing / coating product manufactured under conditions of low temperature and long drying time, the coating of ink / coating liquid is compared. Even though the amount of work and the amount of residual solvent are the same, the latter has uniform quality over the entire printing / coated surface and there is no problem in performance, whereas the former has, for example, stripes due to differences in surface conditions. Uneven gloss appears, or unevenness of physical properties (adhesiveness, releasability,
There was a quality problem that the transferability etc. appeared.

That is, there are portions where the adhesiveness between the ink and the base material is weak at approximately equal intervals in the width direction of the base material. As a result, weakly adhered parts are taken by the guide roller during printing and printing / painting. The problem that streak-shaped ink bleeding occurs parallel to the direction in which the substrate is transferred to the work surface, or similarly,
As a result of forming parts with different releasability on the ink surface, when two coated substrates are laminated and then peeled off, the part with reduced releasability does not peel off. there were. Alternatively, when printing or coating transfer foil or transferable ink, uneven transfer occurs, resulting in defective transfer or unevenness of the transferred ink density as stripes at approximately equal intervals parallel to the transfer direction of the substrate. There was a problem.

The present inventors have conducted intensive studies on the cause. As a result, it was found that the mechanism of drying had a problem. It affects not only the amount of heat transferred from the hot air during the drying of the ink / coating liquid printed / coated on the substrate, but also the amount of heat transferred from the guide roller heated by the hot air through the substrate, When the temperature inside the drying unit rises due to the rise in hot air temperature, the amount of heat transferred from the guide roller, which has a higher thermal conductivity than hot air, becomes more dominant in the drying of the ink / coating liquid.
Under such conditions, when contact irregularity between the base material and the roller occurs due to the corrugation of the base material on the roller, etc. The amount of heat transferred to the ink through the material will be different. This difference in the amount of heat transfer causes uneven drying of the ink, that is, a difference in the history of drying, which significantly deteriorates the quality of the printed matter / coated material.

The undulation of the undulation of the substrate can be explained as follows. That is, while printing is in progress, an air layer on the surface of the base material is being conveyed along with the base material, and this air layer is present between the base material and the guide roller even at the contact portion, Try to keep it floating from the roller. On the other hand, since tension is applied to the base material, a force is exerted on the entire base material so as to bring it into close contact with the roller. Due to these contradictory forces, when the base material is focused in the width direction, the entire base material cannot be in a state of uniformly adhering or floating to the roller, and the base material has undulations and is not in contact with the roller. Stable with the contact area. As described above, FIG. 4 is a schematic diagram showing a contact state between a conventional guide roller having a flat surface and a substrate. FIG.
2 is a guide roller, 6 is a base material sheet, 13
Is a portion having a high thermal conductivity, 14 is a portion having a low thermal conductivity, and 15 is an ink layer.

The present invention has been made in view of the above circumstances, and is free from various problems such as uneven gloss on the surface of the dried film due to uneven drying of the ink / coating liquid and other uneven physical properties, and the residual solvent. High quality printed matter
It is an object of the present invention to provide a drying unit and a coating device that can obtain a coated product.

[0009]

The above object can be achieved by the present invention described below. That is, the present invention is a guide roller support type drying unit, wherein the surface of the guide roller is mat-shaped. In the present invention, the surface roughness of the guide roller having a matte surface is such that the center line average roughness Ra is 0.8 μm ≦ R.
a ≦ 35 μm or ten-point surface roughness Rz is 3.0 μm ≦ R
a drying unit with z ≦ 90 μm. Here, the center line average roughness Ra and the ten-point surface roughness Rz are measured values based on JIS-B0601 of the JIS standard (the same applies hereinafter). The present invention is also a coating apparatus in which a guide roller support type drying unit is installed, wherein the guide roller has a matte surface. In the present invention, the surface roughness of the guide roller having a matte surface has a center line average roughness Ra of 0.8 μm ≦ Ra ≦ 35.
μm or ten-point surface roughness Rz is 3.0 μm ≦ Rz ≦ 90
The coating device is μm.

[0010]

In the drying unit and coating apparatus of the present invention,
Since the surface of the guide roller in the drying unit is mat-shaped, an air escape path is created and unevenness of contact with the guide roller due to corrugation of the base due to air entrapment etc. does not occur, and the base guide roller The state of close contact with is extremely stable. Moreover, since the surface of the guide roller is mat-shaped, the contact area between the base material and the roller is small, and the amount of heat transferred from the roller to the base material is small. Therefore, the amount of heat transferred from the roller to the ink is small,
Even if contact unevenness occurs between the base material and the guide roller, the difference in heat transfer amount between the contact portion and the non-contact portion is small, and uneven drying of the ink and the coating liquid does not occur.

The surface roughness of the mat is the surface roughness of a conventional guide roller (for example, the surface roughness Ra = 0.1 μm, R
When the value is close to z = 1.1 μm, it is not possible to completely prevent the inclusion of air, and thus waviness of the base material may occur.
For this reason, it is preferable to make the surface of the guide roller matte, but the surface roughness of the matte surface is Ra = 0.8 μm.
By setting the above or Rz = 3.0 μm or more, it becomes possible to effectively prevent the inclusion of air. In addition, there are various methods for processing the surface of the guide roller into a matte shape, and the present invention is not limited by the method and material. For example, in addition to sandblasting, engraving, chemical etching, etc. on the surface of a conventional metal guide roller, a method of providing a matte layer on the surface of the guide roller by providing a layer of another material by ceramic spraying or the like can be considered.

However, by further increasing the surface roughness of the mat surface, the effect of preventing the inclusion of air remains the same, but problems other than inclusion of air may occur depending on the material of the mat surface. That is, in the case of using a roller having a high surface hardness such as sandblasted, ceramic sprayed, engraved on the surface of the metal roller as described above, when the surface is extremely roughened, the surface irregularities scratch the base material. Sometimes. Therefore, in this embodiment, when the surface roughness was Ra = 35 μm or less or Rz = 90 μm or less, the inclusion of air and the damage to the substrate could be prevented, but Ra = 45 μm or Rz = 130 μm was set. The rollers prevented the inclusion of air, but scratched the base material. From the above, it is possible to prevent the inclusion of air and to prevent uneven drying.
The matte surface has a surface roughness of 0.8 μm ≦ Ra ≦ 35 μ in order to obtain a high-quality printed matter without other problems such as scratches.
It is preferable that m or 3.0 μm ≦ Rz ≦ 90 μm.

[0013]

The present invention will be described below based on the preferred embodiments. FIG. 1 is a side view showing a configuration of a drying unit of the present invention and a gravure printing machine having the drying unit.
In FIG. 1, 1 is a drying unit and 2 is a drying unit 1.
Guide rollers, 3 is a drying hood of the drying unit 1,
4 is a frame of the printing unit 1 of the gravure printing machine, 5 is a printing plate for gravure printing mounted on the frame 4, 6 is a base sheet, 7 is a motor for driving the printing machine, 8 is power to each printing unit It is the driving shaft.

The operation of the gravure printing machine having the above configuration will be described. The base material sheet 6 is mounted as a winding body on a shaft of a feeder of a gravure printing machine, one end thereof is a winding core of the winding body, and the other end thereof is a feed roller, a tension detecting roller, or a printing machine. It reaches the printing unit via a guide roller. After printing is performed by passing between the printing plate 5 and the impression cylinder, the drying unit 1 is entered and drying is performed.

The drying hood 3 is supported by a frame 4 or a beam fixed to the frame 4 so as to be openable and closable. When the drying hood 3 is opened, the base material sheet 6 is passed through and the drying unit 1 is guided. The roller 2 can be cleaned and the like, and the roller 2 is closed during the actual drying. The guide roller 2 is rotatably supported by the frame 4, and rotates along with the transfer of the base sheet 6 in contact with the guide roller 2. When the rotation resistance of the guide roller 2 becomes a problem when the base material sheet 6 is thin and not sufficiently strong, the guide roller 2 is adjusted so that the peripheral speed of the guide roller 2 matches the transfer speed of the base material sheet 6.
Is forcibly driven.

On the opposite side of the guide roller 2 of the drying unit 1 with respect to the base sheet 6, there is a hot air blowing nozzle integrally attached to the drying hood 3. That is, the guide roller 2 has a role as a transfer guide for the base sheet 6, and a role for preventing the position of the base sheet 6 from swinging by receiving the pressure of hot air blown from the nozzle during drying.

The hot air is generated by blowing air into the heater unit by a blower at a place different from but close to the drying unit 1. The hot air coming out of the heater unit is guided to the drying unit by the air supply duct and blown out from the nozzle provided in the duct. The hot air blown off is blown onto the surface of the base material sheet 6 to remove the solvent from the ink film and become hot air containing the solvent,
Collected in the exhaust duct. A part of the hot air containing the solvent in the exhaust duct is guided to the processing device, and the solvent is detoxified and deodorized and discarded. Further, a part of the hot air containing solvent in the exhaust duct is mixed with fresh air containing no solvent, guided by the duct, and again sent to the heater unit by the blower to generate hot air.

After leaving the drying unit 1, the substrate sheet 6 is
Transferred through the guide roller of the gravure printing machine,
Further processing is performed in another printing unit or the like. Finally, the base sheet 6 is passed through a gap between the drive roller and the nip roller, which pulls and transfers the base sheet 6, and is wound up in the winder unit of the gravure printing machine.
It becomes a processed roll.

FIG. 2 is a perspective view of the guide roller 2 used in the drying unit 1 of the present invention. Further, FIG. 3 is a side view of the guide roller 2 used in the drying unit 1 of the present invention as viewed from the axial direction. FIG. 3 (a) shows a guide roller in which the surface is matted by subjecting a metallic guide roller to sandblasting, and FIG. 3 (b) is a metallic guide roller provided with a layer of another material and matted. It is a guide roller. 2 and 3,
Reference numeral 9 is a surface layer of the guide roller 2, 10 is a pillar of the guide roller 2, 11 is a tapered portion at the end of the pillar 10, and 12 is a shaft of the guide roller 2.

The column 10 is usually a hollow cylindrical column, that is, a cylinder, and the material thereof is a light metal such as aluminum or a light alloy so that the rotational moment is small and sufficient strength is obtained. . The tapered portion 11 is fitted into the column 10 at a wide taper portion, and the shaft 12 is attached at a narrow taper portion. For example, the tapered portion 11 and the shaft 12 are integrally formed by cutting out from a cylindrical raw material. As the material of the taper portion 11 and the shaft 12, the same material as that of the pillar 10 or steel, stainless steel or the like having higher strength is used. Then, the surface layer 9 is formed on the surface of the pillar 10. The surface layer 9 is a layer having a matte surface, and may be a surface layer formed by treating the material surface of the pillar 10 itself or a surface layer formed by providing a layer different from the pillar 10. (See below).

In this way, trimming or embedding of a balance weight of lead or the like is performed on the side surface of the guide roller 2 so that the guide roller 2 thus manufactured can be rotationally balanced around the shaft 12. An inner ring of a ball bearing is fitted on the shaft 12 and fixed by a ring. Then, the outer ring of the ball bearing is supported by a holder in which a hole having a diameter slightly larger than the outer diameter of the outer ring of the ball bearing is supported, and the guide roller 2 is fixed to the frame 4.

The surface layer 9 of the guide roller 2 is characterized in that its surface is mat-shaped. With such a configuration, the contact state of the base material with the guide roller becomes extremely stable, and the heat transfer coefficient also becomes low. However, since the inclusion of air cannot be completely prevented with the surface roughness close to that of the conventional guide roller, the center line average roughness Ra is 0.8 μm or more, or the ten-point average roughness Rz is 3.0 μm or more. It is preferable. Further, when the unevenness of the roller may damage the base material due to the material of the mat surface or the like, if the surface roughness is increased, the scratches are likely to occur. In the case of the present embodiment, when the relationship between the surface roughness and the scratch was examined, no scratch was generated when Ra = 35 μm or less or Rz = 90 μm or less, but Ra = 45 μm or R
When z = 130 μm, the base material was scratched. From the above, the surface roughness of the matte surface is 0.8 μm ≦ Ra ≦ 35 μm or 3.0 μm ≦ in order to prevent uneven drying due to the inclusion of air and to obtain a high-quality printed matter without other problems such as scratches. It is preferable that Rz ≦ 90 μm.

There are various methods for obtaining such a mat-shaped surface of the guide roller 2, and the present invention is not limited by materials and methods. For example, in addition to sandblasting, engraving, and chemically etching the surface of a conventional metal guide roller, another material such as a ceramic layer is provided on the surface of the metal guide roller, for example, by ceramic spraying, or another synthetic resin or natural resin. A layer of various fibers, an inorganic material, or the like may be provided by a well-known method, and may be matted.

Next, the physical properties of the ink film printed by the drying unit of the present invention and the gravure printing machine will be described with reference to an example comparing the conventional physical properties. (Example 1) Printing conditions: Drying temperature: 2 levels of 50 ° C and 100 ° C Dry air flow rate: 20 m / min Drying time: 1.5 seconds Base material: Polyester film ink with a thickness of 6 μm; Dye ink (solvent system) evaluation; Visually judge the gloss unevenness of the ink film surface; measure the residual solvent per 1 m ²

Printing was carried out using the guide rollers of the surface layer shown in Table 1 below in the printing unit.

[Table 1] Here, the center line average roughness Ra and the ten-point surface roughness Rz are
It is a measured value based on JIS-B0601 of JIS standard.

The results of printing using the above guide rollers are shown in Table 2 below.

[Table 2] When full solid transfer is performed with low energy (voltage of 70% of standard energy) with a printer for evaluation, gloss unevenness ∘: the entire screen has a uniform density. X: A streak-like portion with different density appeared in the marked screen. Scratch of base material ○: No scratch is found on the base material. B: The base material was scratched.

Although the present invention has been described with reference to the embodiment, the present invention is not limited to this embodiment, and all modifications made within the spirit and technical idea of the present invention are also included in the present invention. Needless to say, it is included in. For example, although an example of a gravure printing machine was shown as a coating apparatus in the examples, if the apparatus uses a drying unit of a hot air drying system, the present invention is not limited to a printing machine in a narrow sense and the type of coating apparatus. It is clear that it can be applied. In the present invention, the difference between the printing machine and the coating apparatus is simply the presence or absence of the need for the ink film to form a pattern, and even in the gravure printing machine, the coating apparatus can be used if printing is performed with a uniform amount of ink over the entire surface. Is no different. Therefore, the printing machine referred to in the present invention includes a coating device.

[0028]

According to the present invention, since the surface of the guide roller in the drying unit is formed in a matte shape, an air escape path is formed and uneven contact with the roller due to corrugation of the base material due to air entrapment etc. does not occur. The contact state of the base material with the guide roller becomes extremely stable. As for the surface roughness of the guide roller having a matte surface, the center line average roughness Ra was 0.8 μm ≦ Ra ≦ 35 μm, or the ten-point average roughness Rz was 3.0 μm ≦ Rz ≦ 90 μm. The amount of heat transferred from the surface of the base material to the base material is an appropriate amount, contact unevenness between the base material and the guide roller does not occur, and there is no drying unevenness of the ink / coating liquid. Even if contact unevenness between the base material and the guide roller occurs, the amount of heat transferred from the guide roller to the base material is small and the unevenness of drying of the ink and the coating liquid does not occur. Therefore, according to the present invention, there are no problems such as uneven gloss on the surface of the dried film due to uneven drying of the ink / coating liquid and other unevenness in physical properties, and it is possible to raise the hot air temperature and reduce the residual solvent. A drying unit and a coating device capable of obtaining a printed matter / coated matter of high quality.

[Brief description of drawings]

FIG. 1 is a side view showing a configuration of a drying unit of the present invention and a gravure printing machine including the drying unit.

FIG. 2 is a perspective view of a guide roller 2 used in the drying unit 1 of the present invention.

FIG. 3 is a side view of the guide roller 2 used in the drying unit 1 of the present invention as seen from the axial direction.

FIG. 4 is a schematic view showing a contact state between a conventional guide roller having a flat surface and a substrate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Drying unit 2 Guide roller 3 Drying hood 4 Frame 5 Printing plate 6 Base material sheet 7 Motor 8 Driving shaft 9 Surface layer 10 Struts 11 Tapered part 12 Shaft 13 High thermal conductivity part 14 Low thermal conductivity part 15 Ink layer

Claims (4)

[Claims] 1. A guide roller support type drying unit, wherein the surface of the guide roller is mat-shaped. 2. The surface roughness of the guide roller having a matt surface according to claim 1, wherein the center line average roughness Ra is 0.8 μm ≦ Ra ≦ 35 μm, or the ten-point surface roughness Rz is 3.0 μm. Drying unit characterized in that ≦ Rz ≦ 90 μm. 3. A coating apparatus in which a guide roller support type drying unit is installed, wherein the surface of the guide roller is mat-shaped. 4. The surface roughness of the guide roller having a matt surface according to claim 3, wherein the center line average roughness Ra is 0.8 μm ≦ Ra ≦ 35 μm, or the ten-point surface roughness Rz is 3.0 μm. ≦ Rz ≦ 90 μm, a coating apparatus.