Patent Grant
6986916
1. Field of the Invention
The present invention relates to an apparatus and a method thereof for applying a coating solution on a continuous base (hereinafter web) with a solution in slide bead method for producing photographic film, photographic paper, photosensitive printing material, medical photosensitive material, micro film, magnetic recording tape, adhesive tape, pressure sensitive recording paper, thermosensitive recording paper, off-set printing material, film for liquid crystal display, and the like.
2. Description Related to the Prior Art
In a coating apparatus for applying a coating solution on a web in a slide bead method, a method for regulating a form of edges of the coating solution are disclosed in Japanese Patent Laid-Open Publications No. 55-84577, 10-128212, 10-151397, 10-165870, and 10-165872. In the method disclosed in the publications, a thickness of a coating layer at the edge is regularized by forming the best shape of an edge plate for regularizing a width of the solution on a slide surface, by blowing an air blow to the edge, and inserting a slot to the edges and the like.
However, the above mentioned coating apparatus has complex structure for which fine adjustments are necessary. When the coating apparatus is renewed, a difference of accuracy between the coating apparatuses causes to prevent from being in the best condition.
A method for solving the problem is disclosed in Japanese Patent No. 3-71185 and Japanese Patent Laid-Open Publication 7-502685. However, the coating apparatus described in the former publication often causes a defect of the edges of bead. Further an operation of the coating apparatus described in the latter publication is not so easy as to make a positional adjustment of an edge plate with a hopper edge guide device, and the determination of position of the edge plate is hard.
Further as shown in
An object of the present invention is to provide a coating apparatus having a simple structure for which adjustments are easily carried out.
Another object of the present invention is to provide a coating apparatus with which a difference in a distribution of applying a coating solution on a web is not so large that a defect in drying may not occur.
Still another object of the present invention is to provide a method of applying a coating solution on a continuously feeding web with a coating apparatus, in which adjustments of the coating apparatus are easily carried out.
Still another object of the present invention is to provide a method of applying a coating solution on a continuously feeding web with a coating apparatus, in which a difference in a distribution of applying a coating solution on the web is not so large that a defect in drying may not occur. When Db is a minimum thickness of bead at vena contracta and Ds is an upper limit of a height of said regulation portion, then Db and Ds are represented as follows,
Db(m)=1.03×h1−1.50×he×U−1/3+12800×he2×U
Ds(m)={3×η×q/(ρ×g×sin α)}1/3
Herein,
Further, a height of the regulate portion Dg may satisfy a condition 0.15 mm≦Dg≦5 mm. On the uppermost of the regulate portion is formed a side inclination portion which is inclined to the slide surface.
Otherwise, the edge member has a front end portion provided so as to be parallel to a tangent line at a lowest position of applying the coating solution on the web. A height of the end portion is lower than 0.6 mm. Further on the uppermost of the front end portion is formed a front inclination portion which is inclined to the slide surface.
In a method for coating a coating solution, a coating solution is applied on a web with a coating apparatus of slide bead type that has an edge member provided for regulating a width of the coating solution flowing on a slide surface. The regulate portion is provided to be perpendicular to the slide surface, and an edge of the regulate portion contacts to the slide surface. A height Dg of the regulate portion satisfies a condition Db≦Dg≦Ds, in which Db and Ds is represented as follows:
Db(m)=1.03×h1−1.50×he×U−1/3+12800×he2×U
Ds(m)={3×η×q/(ρ×g×sin α)}1/3.
Herein,
Further, a height of the regulation portion Dg may satisfy a condition 0.15 mm≦Dg≦5 mm.
Otherwise, the edge plate includes an end portion provided so as to be parallel to a tangent line at a lowest position of applying the coating solution on the web. A height of the end portion is lower than 0.6 mm.
The edge member may be constructed of a plate body and an end block attached to the plate body. In this case, it is preferable that the end block is fixed to the plate body with screws.
According to the invention, as the edge member of the coating apparatus is formed so as to satisfy the above conditions, the adjustments of the coating apparatus is easily made, and the difference in a distribution of applying a coating solution on a web is not large that a defect in drying may not occur.
The above objects and advantages of the present invention will become easily understood by one of ordinary skill in the art when the following detailed description would be read in connection with the accompanying drawings.
As shown in
Note that the temperature of the web 15 is adjusted by a temperature adjustment device 80 before applied with the coating solution 17, such that the temperature may be 30–40° C. when receiving the coating solution 17.
The feeding velocity U of the web 15 is between 1–6 m/s, preferably. Further the die 11 includes a vacuum chamber 81 for sucking or aspirating an air below the bead 18, such that the pressure Pb below the bead 18 becomes smaller than the normal pressure P0 above the bead 18. Note that a difference P0–Pb is preferable to be between 300 and 1000 Pa, particularly between 400 and 700 Pa.
The web 15 coated with the coating layer 19 is fed to a drying section (not shown) by a feed roller 82. In the drying section, the solvent in the coating layer 19 evaporates and dries to form a product.
[Web]
The web 15 is for example, a paper, a plastic film, a resin coated paper, a synthesized paper and the like. However the web is not restricted in them. Materials of the plastic film are for example polyolefine (polyethylene, polypropyrene, and the like), and vinyl polymer (vinyl acetate, polyvinylchloride, polystyrene and the like). Further, there are polyamide (nylon-66, nylon-6 and the like), polyester (polyethylene terephthalate, polyethylene-2,6-naphthalate, and the like), polycarbonate, and cellulose acetate (cellulosetriacetate (hereinafter TAC), cellulose diacetate and the like). Preferably, under-layer of gelatin and the like is formed on a surface of the web 15. In this case the coating solution is smoothly and effectively applied on the web 15. As a resin for the resin coated paper, the polyolefine, such as polyolefine is usually used. However, it is not restricted.
[Coating Solution]
There are a lot of types of the coating solution used for the present invention. For example, in producing a photosensitive material, the coating solution is used for forming a photosensitive emulsion layer, a under layer, a protective layer, a back layer and the like. Further the coating solution may be used, which forms the adhesive layer, coloring layer, anticorrosion layer, and the like. It is preferable the coating solution contains a water soluble binder or an organic binder. Particularly, the main component of the coating solution is gelatin, latex, polyvinylalchohol, styrene butadiene rubber, and the like, and especially gelatin. However, the coating solution of the present invention is not restricted in it.
[Coating Apparatus]
In
In
In the coating solution has a surface tension to make the size of a surface of the coating solution minimum. The tension causes the vena contracta in the coating solution, and is at the maximum in the bead. The reason is as follows:
As shown in
In order to make the coating of the solution 17 adequately, it is preferable to satisfy the condition Df≦Db. Further, it is preferable the height Df of the end face 20 satisfies the condition 0 mm<Df≦0.6 mm. However, the height Df is not restricted in this condition.
The minimum thickness Db of the bead 18 can be calculated. As shown in
R=2×he×{σ/(η×U)}1/3, (1)
herein he is the thickness (mm), σ is a surface tension, η is a average of viscosity (mPa·S) of coating solution at a share rate in flowing on the slide surface, and U is a feed velocity (m/s) of the web 15. Further, the line O-F is extended toward the web 15 and the extended line reaches the web 15 at a point A. The point A is represented as (−R−he,0). Note that the radius of the back-up roller is much larger than the radius R of the bead 18a and the thickness he. Accordingly, part of the periphery illustrated in
At a point B, a lower meniscus 18b of the bead 18 contacts to the web 15 in
Yb=0.383×(ρ×U×he2/η). (2)
At point C, the coating solution 17 leaves the uppermost of the lip 14. A line B-C between the point B and the point C reaches the horizontal line at an angular β. Accordingly, the point C is represented as (−R−he+h1, −Yb−h1×tan β) in the Cartesian coordinate.
A line O-Dr is perpendicular to the slide surface 13, and crosses with an upper meniscus 18a of the bead 18 at a point E. Accordingly, the length of a line Dr-E is determined as a minimum thickness Db of the bead 18, and a length from a front end of the slide surface to the minimum thickness position Dr of bead is determined as the length Lr of a line C-Dr. The minimum thickness position Dr of bead is represented as (Dx, Dy) in Cartesian coordinate, and Dx and Dy are calculated as follows.
If the point C is represent as (Cx, Cy), the formula of the line C-Dr is:
Y=tan α×(x−Cx)+Cy. (3)
According to the line O-Dr:
tan α=−x/y, therefore:
y=−x/tan α. (4)
The formula (3) and (4) are solved according to (x, y):
x=sin α×cos α×(Cx×sin α/cos α−Cy)=Dy (5)
when the above formula (5) is solved according to y:
y=−cos2α×(Cx×sin α/cos α−Cy)=Dy (6)
Herein, in order to obtain formulae representing Dx and Dy, the coordinate of Cx and Cy are used:
(Cx,Cy)=(−R−he+h1,−Yb−h1×tan β). (7)
As “R” and “Yb” can be diminished from the formula (7) and (1),
Cx and Cy are represented as follows.
Cx=h1−he×[1+2×{σ/(η×U)}1/3] (8)
Cy=−0.383×(ρ×U×he2/η)−h×tan β (9)
As shown in
r=(Dx2+Dy2)1/2 (10)
Db=(Dx2+Dy2)1/2−R (11)
In order to solve according to Dx2+Dy2, the formula (10) is solved from the formula (5) and (6) as follows:
Dx2+Dy2=cos2 α×(Cx×sin α/cos α−Cy)2 (12)
From the formula (11) and (13):
Db=Cx×sin α−Cy×sin α−R (13)
From the formula (8), (9) and (13):
Db =(sin α+tan β×cos α)×h1−sin α×he−2×(sin α+1)×(ρ/η)1/3×he×U−1/3+0.383×cos α×(ρ/η)×he2×U (14)
Further, considering the following conditions:
b1=(sin α+tan β×cos α)
b2=−sin α
b3=−2×(sin α+1)×(σ/η)1/3
b4=0.383×cos α×(ρ/η)
the formula (14) is represented with use of b1–b4 as follows:
Db=b1×h1−b2×he−b3×he×U−1/3+b4×he2×U (15)
In the formula (14), regions of value of α, β, σ, ρ, η are as follows:
b1–b4 has the following values when in using the value of α, β, σ, ρ and η:
b1=0 to 1.03
b2=−0.5 to (−0)
b3=−4 to (−1.5)
b4=6634 to 12767
Considering the significant digit,
b1=1.03, b2=−0(=0), b3=−1.50, b4=12800,
then,
Db=1.03×h1−1.50×he×U−1/3+12800×he2×U (16)
When the minimum thickness Db of the perpendicular wall 22 is enough large, the contraction is prevented. However, when the minimum thickness Db is too large, the thickness of the coating layer 19 on the web 15 becomes inconstant in the widthwise direction. The reason therefor is that the boundary layer of Blasius develops more on the slide surface. In order to prevent it, it is preferable that almost of the coating solution flows in lower part of a top of the perpendicular wall 22 on the slide face 13.
An upper limit Ds of the height Dg of the perpendicular wall 22 is calculated from the following formula shown in “Transport Phenomena (Willey; 1960) P. 35–40” by R. B. Bird et al.
Ds(m)={3×η×q/(ρ×g×sin α)}1/3 (17)
herein, η is averaged viscosity of the coating solution at sharing rate when in flowing on the slide surface, q is a total amount of the flowing coating solution for a predetermined width, ρ is a averaged density of coating solution, and g is the acceleration of gravity.
Now, the minimum thickness position Dr of bead is calculated. According to the formula cos α=(Dx−Cx)/Lr:
Lr=(Dx−Cx)/cos α (21)
The formula 5 is put into Dx of the formula (21), then
Lr={sin α×cos α×(Cx×sin α/cos α−Cy)−Cx}/cos α (22)
therefore,
Lr=−Cx×cos α−Cy×sin α (23)
The formulae (8) and (9) are put into Cx and Cy of the formula (23) respectively, then
Lr=−cos α[h1−he×{1+2(σ/(η×U))1/3}]−sin α×{−0.383×(ρ×U×he2/η)−h1×tan β} (24)
The formula (24) is transformed as follows:
Lr=(−cos α+sin α×tan β)×h1+cos α×he+2×cos α×(σ/η×U)1/3×he×U−1/3+0.383×sin α(ρ/η)×U×he2 (25)
herein h1 is the distance between the web and the die, he is the thickness of the coating layer, and U is a moving velocity of the web.
When the following substitutions are used;
r1=(−cos α+sin α×tan β)
r2=cos α
r3=2×cos α×(σ/η)1/3
r4=0.383×sin α×(ρ×η)
then the formula (25) is transformed as follows:
Lr=r1×h1+r2×he+r3×he×U−1/3+r4×U×he2 (26)
Further, regions of value of α, β, σ, ρ, η are as follows in the formulae representing r1 to r4:
Considering the significant digit of the above values, the formula (26) is:
Lr=−0.270×h1+1.00×he−1.30×he×U−1/3+5320×U×he2 (27)
The tensional rate of surface of the coating solution is the highest at the minimum thickness position Dr of bead where the distance between the upper meniscus and the slide surface is the smallest. Accordingly, the substitutive force of the upper meniscus of the bead tense to the edge plate is most effectively applied at the minimum thickness position Dr of bead. Thereafter, when reaching the web, the coating solution is tensed furthermore. However, the tensional rate is lower than at the minimum thickness position Dr of bead. Accordingly, it is necessary for preventing the contraction that the minimum thickness Db of bead is smaller than the height Dg, and that the edge plate is provided at the minimum thickness position Dr of bead. Therefore, it is required to satisfy the following condition:
Db≦Dg≦Ds (31)
The coating solution is applied without generating contraction by using the edge plate which satisfies the condition of the formula (31).
When the condition of the formula (31) is satisfied, the end face 20 of the edge plate 12 may be retracted from the lip 14 of the die 11. In
As shown in
The averaged viscosity η of coating solution at the share rate in flowing on the slide surface is 30 (mPa·S), a total amount q of the flowing coating solution for a predetermined width is 0.001 {m3/(m×sec)}, the angle α of the slide surface is 15°, the averaged density ρ of coating solution is 1000 (kg/m3), the acceleration of gravity is 9.8 (m/sec2).
When these values are put into the formula (17), the upper limit Ds is 1.5 mm. Accordingly, the height Dg of the perpendicular wall can be 0.15 mm≦Dg≦5 mm, preferably 0.2 mm≦Dg≦1.5 mm. However, in the present invention, the height Dg of the perpendicular wall is not restricted in the region of value.
In
As the fine processing is made on an inner side in a forward part of the edge plate, the forward part is easily broken. As shown in
In
In
Considering heat deformation, it is preferable to form the screw 50 with the same material as the die 11. The material may be metal such as stainless and the like, polymers such as fluoride resin, acetal resin, acryl resin, and another nonmetals. Further, the number of the screw 50 for fixing the edge plate 12 on the die 11 is not restricted in four, which is shown in
The material for forming the edge plate 12 is not especially restricted. However, it is preferable that the perpendicular wall 22 and the inclined wall 23 are formed of a nonmetal such as polymers, in order to prevent the corrosion. It is especially preferable to use the fluoride resin which is excellent in a anticorrosion.
Note that the die 11 has three manifolds 55a, 55b, 55c connected with the slits 41. Three solution elements 19a, 19b, 19c of the coating solution 17 are filled in the manifolds 55a–55c, respectively.
As shown in
Preferably the width L5 is 20 to 100 mm. When the width L5 is less than 20 mm, it is hard to fit the heartwood 26 in the edge plate 12. However the width L5 is not restricted in this description.
Note that the shape of the perpendicular wall 22 is not restricted in the above embodiment. Further, a coating apparatus 60 illustrated in
Also a coating apparatus 70 illustrated in
In followings, examples of the present invention are described. However, the present invention is not restricted in them.
<Experiment 1>
In Experiment 1, there are examples 1–9 and comparisons 1 and 2, in which respective conditions are determined when in applying the coating solution. At first, an explanation about the example 1 is made in detail. In explanations about examples 2–9 and the comparisons 1 and 2, the same is omitted.
The first to third solution elements of the coating solution were prepared for forming the lowest, middle and uppermost sub-layer, respectively. The first solution element contained gelatin (4%), and the viscosity thereof was 80 mpa·s, and the amount of coating was 20 ml/m2. The second solution element contained gelatin (8%), and the viscosity thereof was 150 mpPa·s, and the amount of coating was 100 ml/m2. The third solution element contained gelatin (6%), and the viscosity thereof was 40 mPa·s, and the amount of coating was 10 ml/m2. The viscosity of each of the three solution elements was adjusted by adding the polyvinyl sulfonic acid. A dyne was added into the second solution element for the middle sub-layer, and thickness of the coating layer formed on the web was evaluated from an optical density. An aerosol OT was added in the third solution element for the uppermost sub-layer, to adjust the surface tension to 27×10−3 (N/m).
In order to apply the above coating solution on the web, the coating apparatus 10 illustrated in
The velocity of coating of the coating solution was 2 m/s. The temperature of the coating the coating solution was 35° C. Thereby the averaged density ρ of the coating solution was 1000 kg/m3. The total flowing amount q of the coating solution in a predetermined width was 3×10−4 m3/(m×sec). The viscosity η of the coating solution at the share rate on the slide surface was 100 mPa·s. The upper limit Ds of the height Dg of the perpendicular wall 22 was calculated from these conditions of ρ, q, η, the angle α of the slide surface and the acceleration g (m/sec2) of gravity, to be 3.288 mm.
Note that a TAC was used as the web 15. According to the coating condition, the moving velocity U of the web was 2 m/sec, the distance h1 between the lip and the web was 0.20 mm. The thickness he of the coating layer 19 was 0.15 mm. The minimum thickness Db of bead was calculated by putting these values of U, h1 and he into the formulae (15) and (16). The minimum thickness Db of bead was 0.181 mm.
The thickness of coating layer of each sample film was measured at a position 10 mm from edges. The thickness at the position was compared with the thickness at the middle position in the widthwise direction of the sample film. In the experiment 1, the difference of the thickness between at the position and the middle position was less than 1%. Further, conditions in the edges of the coating layer were checked with eyes. The result thereof was “good”.
In Examples 2–9 and Comparisons 1 and 2, some conditions is changed.
The conditions of Examples 1–9 and Comparisons 1 and 2 are shown in Tables 1–4 for easily understanding. In table 1 and 4, the distance De between the end face and the lip of the die has a negative value when the end face protrudes from the lip as shown in
In Table 3, the estimation was positive or good (describes as “P”) when the coating layer is formed on the web without problem, and was negative (describes as “N”) when the coating layer is formed on the web with problem.
Table 4 teaches the relation between the estimation in Table 3 and conditions of Db, Dg and Ds in Tables 1–3.
When the condition Db≦Dg≦Ds was satisfied, the estimation of the coating layer formed on the web is positive.
<Experiment 2>
In Experiment 2, the edge plate was attached to the die (Example 10), and the end block is changed (Example 11). However, a method of attachment of the edge plate to the die and that of change of the end block were not restricted in the following Examples 10 and 11.
As shown in
[Comparison 3]
The edge plate is formed of fluoride resin only. The screws were tightened to fix the edge plate on the die at a predetermined position, such that there may be no space between the edge plate and the die. Thereby the end of the edge plate moves for 500 μm forwards. Then the coating of the coating solution was carried out, the edge plate touched and damaged the web. Further, an forward end of the edge plate is broken.
[Experiment 11]
The edge plate used in Experiment 11 had the plate body 12a and the end block 12b as illustrated in
Various changes and modifications are possible in the present invention and may be understood to be within the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2002-016017 | Jan 2002 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 5332440 | Hirshburg | Jul 1994 | A |
| 5837324 | Yapel et al. | Nov 1998 | A |
| Number | Date | Country |
|---|---|---|
| 3037612 | May 1982 | DE |
| 1061412 | Dec 2000 | EP |
| 55-84577 | Jun 1980 | JP |
| 59203666 | Nov 1984 | JP |
| 61057260 | Mar 1986 | JP |
| 3-71185 | Nov 1991 | JP |
| 10-128212 | May 1998 | JP |
| 10-151397 | Jun 1998 | JP |
| 10-165870 | Jun 1998 | JP |
| 10-165872 | Jun 1998 | JP |
| WO 9408272 | Apr 1994 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 20030180465 A1 | Sep 2003 | US |
