Patent Application
20080000418
Now, a preferred embodiment of a coating device and a coating method according to the present invention will be described with reference to the accompanying drawings.
The bar 12 is formed into a cylindrical shape, and rotatably supported by the bar support member 14. The bar 12 rotates around an axis in contact with the lower surface of the running web W. The rotational direction of the bar 12 is preferably opposite the running direction a of the web W, and the circumferential velocity of the bar 12 is set to 1% or lower of the running speed of the web W. The rotational direction of the bar 12 may be the same as the running direction a.
The bar 12 may have a smoothly finished surface, have grooves at circumferentially equally spaced intervals, or have a wire tightly wound therearound. The diameter of the wire wound around the bar 12 is preferably 0.07 to 1 mm, and more preferably 0.07 to 0.4 mm. For a bar having grooves or having a wire wound therearound, the depth of the grooves or the thickness of the wire is reduced to reduce a coating thickness of a photosensitive layer forming liquid, and the depth of the grooves or the thickness of the wire is increased to increase the coating thickness of the photosensitive layer forming liquid.
The diameter of the bar 12 is preferably 6 to 25 mm in terms of manufacture because vertical streaks rarely occur in a coating film of the photosensitive layer forming liquid formed on the web W. The bar 12 generally has a length longer than the width of the web W, but may have the length equal to the width of the web W.
The web W comes into contact with the bar 12 with tension at a predetermined lap angle. An angle θ1 formed by the web W on an upstream side and a horizontal surface (an angle of approach) is preferably 3° to 30°, and more preferably 5° to 10°. The angle of approach θ1 is set within such a range to prevent thick coating at the start and finish of coating and prevent friction of the bar 12 as described later. An angle θ2 formed by the web W on a downstream side and the horizontal surface (an ejection angle) is not limited, but set so that the lap angle calculated from θ1 and θ2 becomes a predetermined value.
The bar support member 14 is formed by assembling a plurality of blocks, and has an upper surface formed with an arcuate groove 14A. The bar 12 engages the groove 14A and is rotatably supported by the groove 14A. On an upstream side of the groove 14A in the running direction a of the web W (hereinafter, simply referred to as an upstream side), an upstream upper surface 14B inclined to the horizontal surface is formed. When an angle formed by the upstream upper surface 14B with respect to the horizontal surface is γ (see
On a downstream side of the groove 14A in the running direction a of the web W (hereinafter, simply referred to as a downstream side), a downstream upper surface 14C is formed. The downstream upper surface 14C is formed in a lower position than the upstream upper surface 14B. A wall surface 14D on an upstream side of the bar support member 14 is vertically formed, and the sheathing board 16 is placed to face the wall surface 14D on an upstream side thereof.
The sheathing board 16 is a plate-like member vertically provided, and has a lower end secured to the base 18. As shown in
The upper end 16A of the sheathing board 16 is formed in a straight line along the width of the web W, and parallelism of the upper end is set within 0.01 mm to 0.2 mm. Smaller parallelism increases advantages described later but increases machining costs, and thus the parallelism is preferably 0.01 mm or more, and more preferably 0.05 mm or more.
Because the upper end 16A of the sheathing board 16 is thus formed into an acute wedge in a straight line along the width of the web W, a contact line is formed in a straight line along the width of the web W and coating liquid passing through a clearance between the web W and the upper end 16A of the sheathing board is pressurized. This effectively prevents entrained air on the surface of the web from being brought into the coating liquid reservoir portion A (described in detail below) through the contact line. This allows stable coating without any defective coating when line speed of the web W (i.e. running speed of the web) is increased for high-speed coating.
In addition, it is preferable that an angle α formed by the tapered surface 16B formed in the sheathing board 16 and the web W is in the range of 45°≦α≦90°. The vertex angle δ of the sheathing board 16 may be changed to change the angle α. The angle α thus formed by the tapered surface 16B and the web W in the range of 45°≦α≦90° facilitates the escape of entrained air, which has been blocked at the contact line, downwardly along the tapered surface 16B, so that the effect of blocking entrained air at the contact line can be further improved. In addition, forming an L-shaped flow of entrained air escaping downwardly from the lower surface of the web W along the tapered surface 16B facilitates formation of stable beads of coating liquid in a clearance between the web W and the upper end 16A of the sheathing board 16. This stabilizes a flow of coating liquid passing through the clearance between the web W and the upper end 16A of the sheathing board 16, and subsequently, pressure of a coating liquid reservoir portion A.
As shown in
The upper end 12A of the bar 12 is preferably placed in a higher position than the upper end 16A of the sheathing board 16: that is, the height difference H between the upper end 12A of the bar 12 and the upper end 16A of the sheathing board 16 is positive. The upper end 12A of the bar 12 thus placed in a higher position than the upper end 16A of the sheathing board 16 allows an excess coating liquid scraped off by the bar 12 to flow in the direction from the bar 12 to the sheathing board 16. This allows the coating liquid to flow oppositely from the direction of entrained air brought in, more effectively preventing entrained air from being brought into the coating liquid reservoir portion A.
The sheathing board 16 is provided in parallel with the wall surface 14D of the bar support member 14 with a predetermined clearance, and a slit-like supply channel 24 is formed therebetween. The slit width C3 of the supply channel 24 is preferably narrow because discharge pressure can be increased without changing a supply amount of the coating liquid (the photosensitive layer forming liquid).
As shown in
The temporary storage chamber 26 has the function of temporarily storing the supplied coating liquid, and preventing changes in flow rate of the coating liquid supplied from the supply channel 24 when a discharge amount of the pump P changes. The coating liquid supplied to the temporary storage chamber 26 flows through the supply channel 24 from the lower end to the upper end, and is discharged from the exit in the upper end of the supply channel 24 toward the lower surface of the web W. This forms the coating liquid reservoir portion A in a space surrounded by the lower surface of the web W, the upstream upper surface 14B of the bar support member 14, the bar 12, and the sheathing board 16. The coating liquid in the coating liquid reservoir portion A adheres to the surface of the web W, and thus coating is performed. In this case, when a coating width of the coating liquid coated on the web W is L and a vertical section area of the coating liquid reservoir portion A vertically cut in a web running direction is S, it is preferable that S/L≦0.15 mm is satisfied. The reason is that, with an excessively large vertical section area S of the coating liquid reservoir portion A with respect to a coating width L, the coating liquid reservoir portion A is not easily pressurized, as well as being pressurized unevenly.
The supply amount of the coating liquid is set according to running speed L (m/min) of the web W. The spray velocity of the coating liquid sprayed from the exit of the supply channel 24 toward the lower surface of the web W in a form of a curtain is preferably 2.5 m/min to 50 m/min. This forms a fluid wall of the sprayed coating liquid between the exit of the supply channel 24 and the lower surface of the web W, and the fluid wall can block entrained air. When the fluid wall is to be formed, it is also preferable that an angle α formed by the tapered surface 16B formed in the sheathing board 16 and the web W is in the range of 45°≦α≦90°.
As shown in
As shown in
The base 18 is supported by an unshown hoisting and lowering device, and is movable along the height. Thus, the bar 12 can be moved toward the web W (that is, moved upward) and brought into contact with the web W, or the bar 12 can be moved away from the web W (that is, moved downward) and separated from the web W. The running position of the web W may be changed by hoisting or lowering the pass rollers 20 and 22 instead of moving the base 18.
Next, operations of the coating device 10 according to the invention thus configured will be described with reference to
Before the start of the coating, the web W and the bar 12 are apart as shown in
Before the start of the coating, it is preferable that θ3<β is satisfied in terms of the relationship between an angle of approach θ3 of the web W and an angle β formed by a line connecting the upper end 12A of the bar 12 with the upper end 16A of the sheathing board 16 with respect to a horizontal surface.
In this state, the web W is run in the running direction a, the bar 12 is rotated in the direction of arrow, and the coating liquid is discharged from the supply channel 24. At this time, the upper end 16A of the sheathing board 16 is placed in the higher position than the upstream upper end 14E in the upstream upper surface 14B of the bar support member 14, and thus the coating liquid discharged from the supply channel 24 is stored in the discharge port of the supply channel 24. Further, the upper end 12A of the bar 12 is placed in the higher position than the upper end 16A of the sheathing board 16, and thus the supplied coating liquid flows over the upper end 16A of the sheathing board 16 to the upstream side. This prevents the coating liquid from flowing over the bar 12 to the downstream side.
At the start of the coating, the base 18 (see
When such coating liquid is coated on the web W, it is preferable that the spray velocity of the coating liquid sprayed from the exit of the supply channel 24 is 2.5 m/min to 50 m/min and the coating liquid is sprayed from the supply channel 24 toward the lower surface of the web W in a form of a curtain. The reason is that this can form a fluid wall of the coating liquid between the exit of the supply channel 24 and the lower surface of the web W, and the fluid wall can also block entrained air.
In this case, the fluid wall forms an upstream end in the coating liquid reservoir portion A, so that coating liquid from one supply channel 24 can both form a fluid wall and coat the web via the coating liquid reservoir portion A.
On the other hand, because the upper end 12A of the bar 12 is placed in a higher position than the upper end 16A of the sheathing board 16, an excess coating liquid scraped off by the bar 12 flows in the direction opposite to the running direction a, and flows down over the upper end 16A of the sheathing board 16. This flow of the coating liquid generates dynamic pressure in the direction opposite to the running direction a, and thus a film of entrained air carried with the web W in the running direction a is forced out to the upstream side at the position of the upper end 16A of the sheathing board 16. This prevents the film of the entrained air from being brought into the coating liquid reservoir A.
In the embodiment, the upper end 16A of the sheathing board 16 is formed into an acute wedge, thus a portion in which the web W first comes into contact with the coating liquid (hereinafter referred to as a contact line) is formed in a straight line along the width of the web W, and in the contact line, the coating liquid passing through the clearance between the web W and the sheathing board 16 is significantly pressurized. This can effectively prevent the entrained air on the surface of the web W from being brought into the coating liquid reservoir through the contact line. Such a configuration also allows the internal pressure of the coating liquid reservoir A to be increased. Specifically, when the upper end of the sheathing board 16 is formed into a flat shape or an arcuate shape as is conventional, the increase in the internal pressure of the coating liquid reservoir A causes uneven pressure along the width in the clearance between the sheathing board and the web, and the entrained air is easily brought into the liquid reservoir, but this can be prevented by the embodiment.
In the embodiment, when a coating width of the coating liquid coated on the web W is L and a vertical section area of the coating liquid reservoir portion vertically cut in a web running direction is S, S/L≦0.15 mm is satisfied, thereby increasing the internal pressure of the coating liquid reservoir portion A, and effectively preventing entrained air from being brought into the coating liquid reservoir portion A. This can reliably prevent entrained air from being brought into the liquid reservoir even if the running speed L of the web W is increased to cause the entrained air to be easily brought into the liquid reservoir.
The embodiment can also prevent thick coating at the start of the coating.
Specifically, before the start of the coating, because θ3<β is satisfied and the upper end 12A of the bar 12 is placed in a higher position than the upper end 16A of the sheathing board 16, the upper end 12A of the bar 12 first comes into contact with the web W, and thereafter, the upper end 16A of the sheathing board 16 is brought close to the web W to form the coating liquid reservoir portion A, thereby starting the coating. This can eliminate an excess coating liquid insufficiently: scraped off by the bar 12 and prevent thick coating at the start of coating.
In addition, before the start of the coating, the coating liquid-flows over the upper end 16A of the sheathing board 16 down to the upstream side, and the web W is run in a specified position (that is, the position along the dash-double-dot line) to increase the internal pressure of the coating liquid reservoir portion A, and the coating is started. Thus, the coating is not started before the internal pressure of the coating liquid reservoir portion A increases, thereby preventing thick coating at the start of the coating. Specifically, if the coating is started before the increase in the internal pressure of the coating liquid reservoir portion A, the web W passes through the bar 12 with the coating liquid having adhered to the web W being insufficiently scraped off by the bar 12, possibly causing thick coating, but this can be prevented by the embodiment. Thus, the coating liquid coated on the web W can be reliably dried in a downstream drying device, thereby preventing problems caused by transfer of an undried coating liquid as at the occurrence of thick coating. Thus, according to the embodiment, thick coating at the start of the coating can be prevented.
At the finish of the coating, the base 18 (see
One surface of an aluminum web having a width of 1 m was roughened, then anodic oxidation was performed to manufacture a substrate web W. A photosensitive substance, a binder, an activator, a dye, and a viscosity improver were dissolved in an organic solvent to prepare photosensitive layer forming liquids. The photosensitive layer forming liquids having the viscosity of 25 cp and the viscosity of 50 cp were prepared. Then, the bar coater 10 in
In Example 1, an examination was conducted to determine how an angle α formed by the tapered surface 16B of the sheathing board 16 and the web W affects speed at which no defective coating occurs (coating limit speed). The angle α was changed by the vertex angle δ of the sheathing board 16 while the angle of approach θ1 was constant. The slit width in the direction of web width of the supply channel 24 was 1 m, and the slit clearance was 0.5 mm. The test results are shown in Table 1.
As a result, as can be seen from Tests 1 to 5, with the increase of the angle α from 5°, the coating limit speed is also increased. Specifically, when the angle α was 5° in Test 1, the coating limit speed was 70 m/min: however, it reached the maximum, or 150 m/min, when the angle α was 45° in Test 3, and the maximum was maintained up to 80° of the angle α in Test 5. Although tests were not conducted on the angle α of more than 80°, the maximum may be considered to remain up to near 90° that is a limit for fabrication of the sheathing board. Therefore, the preferred range of the angle α is preferably 45°≦α≦90°.
In Example 2, a relationship between C1/C2 and the coating limit speed was examined, where in relation to a parallel line 17 that passes the upper end 16A of the sheathing board 16 and is in parallel with the web W, C1 is a distance from the web W to the parallel line 17 and C2 is a distance from the parallel line 17 to an upstream upper surface 14B of the bar support member 14. The slit width in the direction of web width of the supply channel 24 was 1 m, and the slit clearance was 0.5 mm. The test results are shown in Table 2.
In Table 2, Tests 6 to 11 show the relationship between C1/C2 and the coating limit speed, and Tests 12 to 14 were conducted to determine how narrow the clearance distance C1 can be between the web W and the upper end 16A of the sheathing board 16.
From the results in Table 2, the coating limit speed increases with the reduction of C1/C2: however, the coating limit speed tends to decrease again with excessively small C1/C2. Specifically, when C1/C2 was in the range of 0.17 to 5, the coating limit speed was 150 to 200 m/min and high-speed coating could be performed. Therefore, high-speed coating can be performed without any defective coating within the range of 0.2≦C1/C2≦5.
The Tests 12 to 14 was conducted using the value of C2 in Test 8 whose coating limit speed was the largest among Tests 6 to 12. As can be seen from Test 13, with excessively narrow C1, the web W was brought into contact with the upper end 16A of the sheathing board 16, causing scratches on the web W. However, when C1 is 0.1 mm as shown in Test 14, the coating limit speed increases without scratches on the web W, and therefore, it is required that C1 is not less than 0.1 mm. Incidentally, with excessively large C1 as shown in Test 12, the pressure in the coating liquid reservoir portion A is not easily raised and the coating limit speed tends to decrease.
In Example 3, a relationship between the difference H between the height of the upper end 12A of the bar 12 and the height of the upper end 16A of the sheathing board 16 and the coating limit speed was examined. The distance C1 between the web W and the upper end 16A of the sheathing board 16 was consistently 0.5 mm. The slit width in the direction of web width of the supply channel 24 was 1 m, and the slit clearance was 0.5 mm. The test results are shown in Table 3.
As can be seen from Test 15, when the difference H is a positive value such as 0.2 mm so that the upper end 12A of the bar 12 can be slightly higher than the upper end 16A of the sheathing board 16, the coating limit speed increases to 150 m/min. On the other hand, as can be seen from Tests 16 and 17, when the difference H is zero or a negative value such as −0.2 mm so that both the upper end 12A of the bar 12 and the upper end 16A of the sheathing board 16 have the same height or the upper end 16A of the sheathing board 16 can be slightly higher than the upper end 12A of the bar 12, the coating limit speed decreases to 50 to 70 m/min.
Therefore, It is also preferable that the height difference H between the upper end 12A of the bar 12 and the upper end 16A of the sheathing board 16 is positive to increase the coating limit speed.
In Example 4, an examination was conducted to determine how a relationship between θ3 and β affects thick-coating at the start and finish of coating, where θ3 is an angle of approach of the web W to the bar 12 before the start of coating with respect to a horizontal surface and β is an angle formed by a line connecting the upper end 12A of the bar 12 with the upper end 16A of the sheathing board 16 with respect to a horizontal surface. The slit width in the direction of web width of the supply channel 24 was 1 m, and the slit clearance was 0.5 mm. In this case, the angle β was consistently 20° and the angle of approach θ3 of the web before the start of coating was changed. In Table 4, “Good” indicates occurrence of no thick coating and “Poor” indicates occurrence of thick coating.
As a result, as can be seen from Tests 18 to 19, thick coating could not be prevented at both the start and finish of coating when θ3≧β. However, as shown in Tests 20 to 22, satisfying θ3<β could prevent thick coating from occurring at both the start and finish of coating.
In Example 5, preferred spray velocity was examined when the coating liquid was sprayed from the exit of the supply channel 24 toward the lower surface of the web W to form a fluid wall. The spray velocity was changed by changing the slit clearance of the supply channel 24. The test results are shown in Table 5.
As a result, a good fluid wall was formed at spray velocity of 2.5 m/min or more, and the coating limit speed could be increased up to 150 r/min. Although not shown in Table 5, spray velocity more than 50 m/min caused the impulse of the spray that is too strong to perform coating due to fluttering of the web W. Therefore, spray velocity of the coating liquid sprayed from the exit of the supply channel 24 toward the lower surface of the web W is preferably 2.5 m/min to 50 m/min.
In Example 6, an examination was conducted to determine how θ1/γ affects the coating limit speed, where θ1 is an angle of approach of the web W to the bar 12 in the course of coating with respect to a horizontal surface, and γ is an angle formed by the upstream upper surface 14B of the bar support member 14 with respect to a horizontal surface. The slit width in the direction of web width of the supply channel 24 was 1 m, and the slit clearance was 0.5 mm. The test results are shown in Table 6.
As a result, θ1/γ of less than 0.5 or more than 2 could only achieve the coating limit speed on the order of 100 m/min: while θ1/γ defined within a range of 0.5≦θ1/γ≦2 could result in the coating limit speed of 150 to 200 m/min and high-speed coating could be performed.
In Example 7, a relationship between P/P0 and the coating limit speed was examined, where P is fluid pressure at the exit of the supply channel 24 and P0 is atmospheric pressure. The test results are shown in Table 7.
As a result, P/P0 of 1.0 in Test 31 resulted in the coating limit speed of 100 m/min: while P/P0 of 1.1 increased the coating limit speed up to 120 m/min and P/P0 of 1.2 increased the coating limit speed up to 150 m/min. Therefore, P/P0 is preferably 1.1 or more in order to perform high-speed coating so that no defective coating may occur.
In Example 8, a relationship between a ratio of a vertical section area S of the coating liquid reservoir portion A to a coating width L (S/L) and the coating limit speed was examined. In the case of Example 8, the coating width L was consistently 200 mm and the vertical section area S was changed. Therefore, the slit width in the direction of web width of the supply channel 24 was reduced according to the coating width L, and the slit clearance was 0.5 mm as described above. The test results are shown in Table 8.
As a result, with the reduction of S/L, the coating limit speed tended to increase and was 100 m/min when S/L was 0.15: however, it increased up to 120 m/min when S/L was 0.10 and up to 150 m/min when S/L was 0.08. Therefore, it is preferable that S/L≦0.15 mm is satisfied.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2006-179772 | Jun 2006 | JP | national |
