JP2003340345A - Doctor blade for gravure coating and gravure coating method - Google Patents

Abstract

(57) [PROBLEMS] To provide a gravure that can be applied with a uniform coating amount immediately after the start of use of a doctor blade, and that the distribution of coating amount is less changed with time and that it is difficult to cause streaks and unevenness on the coated surface. A doctor blade for coating and a gravure coating method are provided. A gravure coating doctor blade (3) that presses across the width direction of a gravure roll (1) to which a coating liquid is supplied and scrapes off an excess coating liquid on the surface of the gravure roll (1). The doctor blade 3 has an inclined surface 3b along the width direction at the tip portion on the side pressed against the gravure roll 1, and the distribution range of the inclined surface length Lc of the inclined surface 3b with respect to the width direction with respect to the specified length. Within 30%, and the straightness of the doctor blade alone was less than 50 μm in the waviness in the width direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gravure coating doctor blade and a gravure coating method which are useful for applications where a uniform coating amount distribution is required.

[0002]

2. Description of the Related Art A gravure coating method is well known as a method for coating a coating solution on a film base. As an example of the gravure coating method, as shown in FIG. 12, the coating solution 2 is supplied to the surface of the gravure roll 1 which is rotationally driven, and the surplus of the surface of the gravure roll 1 is applied by the doctor blade 3 pressed against the surface of the gravure roll 1. After scraping off the coating liquid, the coating liquid in the cells of the gravure roll 1 is coated on the film base 4. The doctor blade 3 presses the surface of the gravure roll 1 from the time when the coating liquid 2 is supplied from the coating liquid storage unit 5 to the surface of the gravure roll 1 until it contacts the film base 4.
In FIG. 12, 6a to 6c are guide rolls, and 8 is a drying unit. The film base 4 runs in the arrow Y1 direction, and the gravure roll 1 rotates in the arrow Y2 direction.

The above-mentioned gravure coating method is an example of reverse gravure coating (kiss) in which the gravure roll 1 is rotated in the direction opposite to the transport direction of the film base 4, but in addition to this structure, the direct gravure coating shown in FIG. There is also a gravure coating method using gravure coating (direct). In the configuration using direct gravure coating, the backup roll 14 is arranged in parallel while nipping the gravure roll 1 via the film base 4, and the gravure roll 1 and the backup roll 14 are rotated in the forward direction with respect to the transport direction of the film base 4. It is a thing. The nip pressure between the backup roll 14 and the gravure roll 1 is adjusted by the cylinder 16 that presses the backup roll shaft.

By the way, in each of the above gravure coating methods, the gravure roll 1 is moved by the doctor blade 3.
Although the coating amount distribution in the width direction (axial direction) of the doctor blade 3 is made uniform, a more accurate coating amount distribution can be achieved and a stable coating amount distribution state can be obtained immediately after the doctor blade 3 starts to be used. In order to obtain it, many techniques for optimizing the shape and material of the doctor blade 3 have been proposed.

For example, in Japanese Unexamined Patent Publication No. 2000-202350, a doctor blade having an inclined surface formed at the tip is used, and the inclined surface is pressed against the surface of the gravure roll, whereby the excess coating liquid supplied to the surface of the gravure roll is used. A gravure coating method of scraping off the liquid is disclosed. In the doctor blade in this case, the tip angle (blade angle) of the inclined surface is set to 35 ° to 80 °, and the inclined surface of the doctor blade tip that contacts the gravure roll surface intersects with the tangent line of the gravure roll surface. The angle is set within ± 10 ° so that a stable coating amount distribution can be obtained immediately after the doctor blade starts to be used.

[0006]

In the gravure coating method proposed above, the inclined surface of the doctor blade is pressed as flat as possible against the surface of the gravure roll,
A stable coating amount distribution is obtained. However, this is a case where the doctor blade is pressed against the surface of the gravure roll at a relatively acute angle, and for this reason, it is difficult to obtain a uniform coating amount distribution unless the pressing pressure of the doctor blade is set relatively high. . Therefore, this method has a problem in that the progress of wear of the tip of the doctor blade is accelerated.

On the contrary, when the doctor blade is pressed against the surface of the gravure roll with a low pressure to use it at an acute angle,
The doctor blade may vibrate due to the rotating force of the gravure roll, causing uneven coating.

Further, in general, the doctor blade comes into contact with a gravure roll, and the tip part is abraded as the use time increases. However, if the abrading progresses too much, streaks occur on the coated surface, This causes a problem that the coating amount and the coating amount distribution change.

On the other hand, depending on the coating liquid and the coating conditions, the inclined surface of the doctor blade tip is pressed against the surface of the gravure roll at an obtuse angle to scrape off the coating liquid to apply the coating liquid. In this case, it is particularly effective to use the shearing force generated between the doctor blade and the gravure roll to destroy the solid content in the coating liquid or prevent the physical properties of the coating liquid from changing.

However, also in this case, if the coating amount distribution is to be made uniform, the inclined surface of the doctor blade tip is pressed flat against the gravure roll surface in the same manner as described above, and the tip angle of the inclined surface of the doctor blade tip is adjusted. 35 °
The following may also occur. Naturally, in such a case, the tip angle of the inclined surface of the doctor blade should be 3
The above-mentioned Japanese Patent Laid-Open No. 2000-20235 is set to 5 ° to 80 °
The technology of No. 0 cannot be applied, and since the contact angle between the doctor blade and the gravure roll becomes shallow, the coating liquid scraped up by the gravure roll easily slips through the gap between the tip of the doctor blade and slight turbulence. Therefore, the distribution of the coating amount is deteriorated, and streaks and unevenness are likely to occur in the state after coating. Such a problem cannot be improved even if the thickness of the doctor blade is changed or the pressure applied to the gravure roll is changed.

The present invention has been made in consideration of the above circumstances, and coating can be performed with a uniform coating amount immediately after the start of use of a doctor blade, and the coating amount distribution does not change with time, resulting in streaks and unevenness on the coating surface. It is an object of the present invention to provide a doctor blade for gravure coating and a gravure coating method capable of making it difficult to generate.

[0012]

In order to achieve the above object, the doctor blade for gravure coating according to claim 1 of the present invention is pressed against the surface in the width direction of a gravure roll having a coating solution supplied thereto, A doctor blade for gravure coating that scrapes off excess coating liquid on the surface of the gravure roll, wherein the doctor blade for gravure coating has an inclined surface at a tip end on the side to be pressed against the gravure roll, and an inclined surface of the inclined surface. The distribution range of the length in the width direction is within 30% with respect to the specified slope length, and the straightness of the doctor blade alone is less than 50 μm in the waviness in the width direction. .

In this gravure coating doctor blade, the distribution range of the inclination length of the inclined surface of the blade tip portion in the width direction of the gravure roll is within 30% of the specified inclination surface length, and the doctor blade alone is used. The straightness of the roll is 5 in the width direction of the gravure roll.
Since the thickness is less than 0 μm, the amount of the coating liquid on the surface of the gravure roll can be uniformly controlled in the width direction of the gravure roll, and the uniform coating amount distribution can be achieved with high accuracy. As a result, it is not necessary to lengthen the run-in from the initial stage when a new doctor blade is installed, and productivity can be improved.

The doctor blade for gravure coating according to claim 2 is characterized in that the blade has a plate thickness of 0.5 mm or less.

With this doctor blade for gravure application, the plate thickness of the blade is 0.5 mm or less, so that even if the surface of the gravure roll has a curved surface, the planar pressing surface can be pressed uniformly. .

The doctor blade for gravure coating according to a third aspect of the present invention is characterized in that the tip angle of the inclined surface of the blade tip portion is in the range of 5 ° to 80 °.

In this doctor blade for gravure coating, the workability of the inclined surface of the blade tip portion is impaired by making the entire inclined surface of the blade tip portion a tip angle within the above angle range over the width direction of the gravure roll. In addition, the problem of equipment such as interference between the doctor blade and other members is less likely to occur. Further, the warp of the doctor blade can be utilized to uniformly press the gravure roll in the width direction.

In the gravure coating method according to the fourth aspect, the coating solution is supplied to the gravure roll surface, the excess coating solution on the gravure roll surface is scraped off by a doctor blade pressed against the gravure roll surface, and then the gravure roll surface is removed. A gravure coating method for coating a film base with a coating liquid in a cell, wherein the doctor blade for gravure coating according to any one of claims 1 to 3 is used, and the gravure coating is in contact with the surface of the gravure roll. The angle of intersection of the sloping surface of the tip of the doctor blade and the tangent line at the contact position on the gravure roll surface is ±
The feature is that it is set within 5 °.

In this gravure coating method, the amount of the coating liquid on the surface of the gravure roll can be uniformly controlled in the axial direction of the gravure roll, and the coating amount distribution on the film base can be made uniform.

The gravure coating method according to claim 5 is characterized in that a gravure roll having a diameter of 15 mm or more is used.

In this gravure coating method, the diameter of the gravure roll is set to φ15 mm or more, so that when the diameter of the gravure roll is too small, the deflection of the gravure roll becomes too large and eccentric, and the gravure roll rotates periodically. It is possible to eliminate the problem of uneven application.

The gravure coating method according to claim 6 is 2
The number of grooves per 5.4 mm (1 inch) is 60 to 150
A gravure roll of 0 is used.

In this gravure coating method, the number of grooves is 60 to
When the gravure roll is 1500, the effect of uniformizing the coating amount of the present invention is particularly effectively exhibited.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of a doctor blade for gravure coating and a gravure coating method of the present invention will be described in detail below with reference to the drawings. FIG. 1 shows an explanatory view showing the relationship between the gravure roll and the doctor blade. (A) is a perspective view, (b) is a _Ib direction arrow line view. Hereinafter, the present invention will be described using the configuration of the reverse gravure coating method, but the present invention is not limited to this, and the present invention can be applied to other coating methods such as direct gravure coating.

The gravure coating method of this embodiment is shown in FIG.
As shown in the illustration of the gravure coating direction and coating device,
After the coating liquid 2 is supplied to the surface of the gravure roll 1 rotatably supported between the bearings, and the excess coating liquid on the surface of the gravure roll 1 is scraped off by the doctor blade 3 pressed against the surface of the gravure roll 1. In the method of applying the coating liquid in the cell of the gravure roll 1 to the film base 4, as shown by exaggerating the deflection in FIGS. Almost the same bending is applied to the doctor blade 3 to scrape off the excess coating liquid.

In this case, at least the doctor blade 3
So that the contact end 3a of the tip of the gravure roll 1 contacts the surface of the gravure roll 1, in particular, the same generatrix of the gravure roll surface (the axial line of the roll surface in the state without roll deflection). It suffices if the flexure is given to. The direction I _b in FIG. 1B is the maximum bending direction of the gravure roll 1 (substantially vertical direction).
It is a direction perpendicular to (approximately horizontal direction).

FIG. 2 is a perspective view of the doctor blade (a),
The distribution (b) of the inclination length of the inclined surface of the tip portion with respect to the blade longitudinal direction and the waviness (c) in the blade longitudinal direction are shown. In the doctor blade 3 of the present embodiment, the inclined length (the tip polishing surface length) Lc of the inclined surface 3b of the tip portion extends in the longitudinal direction of the doctor blade 3, that is, in the width direction (axial direction) of the gravure roll 1. , Its distribution range (hereinafter referred to as the distribution range) is 3 with respect to a specified length Lc ₀ such as a design value.
It is within 0%, and the straightness of the doctor blade 3 alone is less than 50 μm in terms of waviness in the gravure roll width direction.

The inclined surface 3b of the doctor blade 3 has a large change in coating thickness when the distribution range of the inclined length Lc in the width direction of the gravure roll exceeds 30%. This will be described with reference to FIG. FIG. 3 is an explanatory view in which the tip portion of the doctor blade and the surface of the gravure roll are enlarged. When the distribution range in the width direction of the gravure roll 1 having the inclined length Lc of the doctor blade tip exceeds 30%, the gravure roll surface 1a and the doctor blade 3
The pressure of the coating liquid 2a passing through between the inclined surface 3b of
The gravure roll 1 has a distribution in the width direction, and the coating thickness of the coating liquid changes greatly due to this pressure difference.
Further, if the straightness of the doctor blade alone is 50 μm or more in the entire width direction of the gravure roll 1, the distance between the inclined length Lc and the gravure roll surface cannot be ignored, as in the above. And the coating thickness changes significantly due to the pressure difference of the coating liquid 2a.

Further, the doctor blade 3 of this embodiment
Is an inclined surface 3b of the doctor blade 3 pressed against the gravure roll 1 as shown in FIG. 4 which is an explanatory view showing a state of a position where the doctor blade is pressed against the gravure roll.
And the intersection angle θ between the tangent line Cp of the surface of the gravure roll 1 at the pressing position P of the doctor blade 3 is −5 ° or more.
It is set to fit within the range of 5 °. By keeping the crossing angle θ within the above range, the change in the gap between the inclined surface 3b and the surface of the gravure roll 1 becomes negligibly small, and a uniform coating thickness can be stably obtained. become. On the other hand, if the crossing angle θ exceeds the above range,
In the area of the inclined surface 3b of the doctor blade 3 facing the surface of the gravure roll 1, the difference in the gap between the surface of the gravure roll 1 on the coating liquid inlet side 3c and the surface of the coating liquid outlet 3d becomes large, and within the area of the inclined surface 3b. Thus, the coating liquid has a pressure distribution, and it becomes difficult for the coating thickness to be constant.

The shape of the tip of the doctor blade 3 and the surface of the gravure roll 1 in FIGS. 3 and 4 are exaggerated in terms of curvature, gaps and the like for convenience of explanation, and are different from the actual shape. ing.

Next, how to obtain the deflection of the gravure roll 1 shown in FIG. 1 will be described with reference to FIG.
First, as the force for bending the gravure roll 1, the vertical component of the tension T of the film base 4 contacting the gravure roll 1, the vertical component of the pressing force P _B of the doctor blade 3 against the gravure roll 1, and the own weight of the gravure roll 1 are used. Exists. The doctor blade 3 is pressed against the surface of a point Q in the direction of an angle b ₁ with respect to the vertical line from the center of the gravure roll 1 at an inclination of an angle b ₂ with the horizontal line. However, each element is set so as to satisfy the following conditions.

(A) Gravure roll own weight> Doctor blade pressing force (b) 0 ° <b ₁ <90 ° (c) −45 ° <b ₂ <45 ° (d) a ₁ ≦ 30 °, a ₂ ≤30 °

That is, according to (a), since the pressing force of the doctor blade is smaller than the own weight of the gravure roll, the horizontal component of the pressing force of the doctor blade becomes sufficiently small. Further, according to (b), the angle b ₁ can be set within a range in which the horizontal force of the doctor blade does not increase and the blade can be easily scraped off. According to (c),
The horizontal component of the doctor blade pressing force can be made smaller than the vertical component. Then, according to (d), the horizontal component due to the tension of the film base can be reduced. Therefore, by satisfying the above conditions (a) to (d), the horizontal force acting on the gravure roll becomes sufficiently smaller than the vertical force and becomes substantially negligible. Also,
The tension of the film base is a ₁ > a ₂
, The horizontal component force is generated in the direction opposite to the horizontal component force due to the pressing force of the doctor blade, so that the force acting in the horizontal direction is substantially canceled. Even if there is a force in the horizontal direction that cannot be ignored, for example, by forming the contact end to the gravure roll described in JP-A-6-55124 into a curved blade shape, the gravure roll axial direction A uniform pressed state is obtained, and thereby the coating amount distribution is made uniform.

Now, it is considered that the maximum deflection of the gravure roll 1 occurs in the vertical direction perpendicular to the axis, and the deflection in the horizontal direction is negligible, and attention is paid only to the vertical force. Since the weight of the gravure roll 1 acts vertically downward, the force C is used as it is. The vertical force A acting on the gravure roll 1 by the tension T of the film base 4 is expressed by the equation (1).

A = Tsin a ₁ + Tsin a ₂ (1) where a ₁ is an angle with the horizontal line on the entrance side of the film base 4, and a ₂ is an angle with the horizontal line on the exit side of the film base 4. Is. Further, the vertical component force B of the pressing force (pressing pressure) P _B of the doctor blade 3 against the gravure roll 1 is represented by the formula (2).

B = P _B cos b ₂ (2) Since the resultant force of A, B, and C acts in the vertical direction, the vertical force P is P = A + B + C (3) For example, the bending in the vertical direction, which is the direction perpendicular to the axis of the gravure roll 1, is obtained by the equation (4) as the bending due to the uniform load on the both-ends supporting beams shown in FIG.

[0037] Deflection ^{= {L 4 P / (2EI} )} [1/2 · {(L-x) / L} 2 -1/12 · {(L-x) / L} 4 ] (4 ) However, P: force that gives flexure to the gravure roll (equal load) E: longitudinal elastic modulus of the gravure roll I: second moment of area of the gravure roll L: gravure roll surface length (bearing distance) / 2 x: gravure roll Distance from axial midpoint

Therefore, the doctor blade 3 is provided with a bending substantially equal to the bending generated in the gravure roll 1 based on the equation (4). As a result, from the initial stage of assembling the doctor blade 3, the contact end 3 of the doctor blade 3 is attached to the surface of the gravure roll 1 which is bent by its own weight or the like.
a is uniformly applied along the roll axial direction. Therefore,
The amount of the coating liquid on the surface of the gravure roll 1 becomes uniform in the roll axis direction, so that the coating amount of the coating liquid can be controlled to a constant amount with high accuracy. 4 can be applied uniformly over the width direction. Further, from the initial stage of newly incorporating the doctor blade 3, it is not necessary to lengthen the run-in operation, and the productivity can be improved.

The deflection amount distribution of the above formula (4) given to the doctor blade 3 is not limited to this, and the deflection amount distribution can be set by approximating with a quadratic or cubic curve. In this case, Also has the same effect as above.

Next, a gravure coating apparatus for realizing the above gravure coating method will be described in detail.

As shown in FIG. 12, the gravure coating apparatus 100 is rotatably driven by a driving means (not shown) to apply the coating liquid 2 to the film base 4, and the coating liquid 2 to the surface of the gravure roll 1. The coating liquid supply unit (the coating liquid storage unit 5) to be supplied and the gravure roll 1 by being pressed against the surface of the gravure roll 1 between the time when the coating liquid 2 is supplied and the time when the coating liquid 2 contacts the film base 4.
It has a doctor blade 3 for scraping off the excess coating liquid on the surface. Then, as shown in FIG. 2, the inclination length Lc of the inclined surface 3b of the doctor blade 3 is a distribution range (hereinafter referred to as a distribution range) in the longitudinal direction, that is, in the gravure roll width direction (axial direction). The specified length Lc ₀
Within 30%, and the straightness of the doctor blade 3 alone is less than 50 μm due to the waviness in the width direction of the gravure roll.

Further, as shown in FIG. 4, the angle of intersection θ between the inclined surface 3b of the doctor blade 3 pressed against the gravure roll 1 and the tangent line Cp of the surface of the gravure roll 1 at the pressing position P of the doctor blade 3 is −. It is set so that it falls within the range of 5 ° to 5 °.

Further, the doctor blade 3 is replaced by the one shown in FIG.
As shown in FIG. 5, at least the contact end 3a of the doctor blade 3 with respect to the gravure roll 1 is provided with a bending substantially equal to the bending in the direction perpendicular to the axis of the gravure roll 1. As a result, the inclined surface 3b at the tip of the blade and the surface of the gravure roll are pressed flat against each other, and the application liquid can be stably applied immediately after the start of the application.

Further, the gravure coating apparatus 100 is provided with a blade holder as a means for holding the doctor blade 3. FIG. 7 shows a sectional view of the blade holder. The blade holder 20 includes two holding plates 21 and 22 that sandwich the base end portion of the doctor blade 3 and two metal blocks 23 that exert a holding force on the doctor blade 3 via the two holding plates 21 and 22. 24 and metal block 2
Fastening bolt 25 and nut 2 for fastening 3, 24 to each other
It is composed of 6 and. Instead of the fastening bolts 25 and the nuts 26, a fluid pressure may be used to obtain a tightening force (a holding force for the pressing plate), and the method for obtaining the holding force for the doctor blade 3 is not particularly limited.
If the accuracy of the holder 20 is sufficient, the doctor blade 3
May be directly sandwiched between the holders 20. The pressing plates 21 and 22 having a thickness of 0.2 to 2 mm can be used.

The length Lb of the doctor blade 3 protruding from the pressing plate 21 of the blade holder 20 is 2 mm to 5 mm.
0 mm, preferably in the range of 3 mm to 20 mm, the type of coating liquid (viscosity, specific gravity, surface tension), process conditions (coating speed,
By setting an appropriate value according to the gravure roll diameter, mesh type, etc., the bending curved surface in the axis vertical direction set on the blade holder 20 side can be faithfully reproduced at the contact end 3a of the doctor blade 3. Further, the width Wb of the doctor blade 3 is set wider as the length in the blade longitudinal direction is larger, and is set to 30 to 200 mm in order to ensure handleability.

The inclined surface 3b of the doctor blade 3
The tip angle β is set to 5 ° to 80 °, more preferably 10 to 45 °, as shown in FIG. When the tip angle β of the inclined surface 3b of the doctor blade 3 is less than 5 °, it is extremely difficult to uniformly process the entire inclined surface 3b of the angled blade tip portion in the width direction of the gravure roll 1. In addition, the blade holder 20 of the doctor blade 3 and the liquid supply portion of the gravure roll 1 interfere with each other, which causes a problem in equipment. On the other hand, when the tip angle β exceeds 80 °, it becomes difficult to uniformly press the doctor blade 3 in the width direction of the gravure roll by utilizing the warp of the doctor blade 3.

The plate thickness t of the doctor blade 3 is 0.
05 mm to 0.5 mm, preferably 0.1 mm to 0.3
mm, and those having appropriate rigidity and flexibility are appropriately used.

[0048] Further, as the pressing pressure of the doctor blade 3, the range of ^{0.01kg / cm 2 ~1kg / cm 2} , more preferably 0.05kg / cm ² ~0.5kg
It is preferable to use in the range of / cm ² .

In the gravure coating apparatus 100,
By bending the blade holder 20 itself, the doctor blade 3 is bent in the same manner as the gravure roll 1. That is, as shown in FIG. 8 in which the doctor blade held by the blade holder is pressed against the gravure roll, both ends of the blade holder 20 are supported by the support members 31, 31.
By supporting the blade holder 20, the central portion of the blade holder 20 is bent in the vertical direction over the longitudinal direction. An up-and-down moving mechanism 3 as a holder bending imparting means in the central portion thereof.
The blade holder 20 is bent downward (in some cases, upward) by applying an external force to the doctor blade 3 so that the doctor blade 3 sandwiched by the blade holder 20 is bent in a direction substantially equal to the bending of the gravure roll 1 in the direction perpendicular to the axis. Is giving. The own weight of the blade holder 20 itself is considered as a part of the external force here. The point of action for applying the external force is not limited to one location in the central portion of the blade holder 20 in the longitudinal direction, but it is preferable to provide it at a plurality of locations at a predetermined interval to more accurately set the bending shape. As the vertical movement mechanism 33, an arbitrary one such as a screw type or a fluid pressure type can be adopted.

Although not shown, the blade holder 20 has a mechanism for attaching / detaching the doctor blade 3 to / from the gravure roll 1. For example, by moving the blade holder 20 back and forth with an air cylinder, The doctor blade 3 can be moved away from the surface of the gravure roll and contacted.

In this way, when the doctor blade 3 is bent by bending the blade holder 20, the bending curve of the doctor blade 3 can be easily changed arbitrarily.

As a method of imparting bending to the doctor blade 3, various methods other than the method of bending the blade holder 20 itself shown in FIG. 9 can be selected. Other methods will be described with reference to FIGS. 10 and 11.

In the blade holder 40 of FIG. 10, the upper and lower metal blocks 23, 24 have a predetermined curvature along the longitudinal direction of the doctor blade 3 on the surfaces 23a, 24a on which the pressing plates 21, 22 are sandwiched. By forming the curved surface, the doctor blade 3 and the pressing plate 21,
22 is bent to give a bending substantially equal to the bending in the direction perpendicular to the axis of the gravure roll 1.

In the blade holder 50 shown in FIG. 11, the pressing plates 21 and 22 change the thickness along the longitudinal direction of the doctor blade 3 so as to form a bending substantially equivalent to the bending in the direction perpendicular to the axis of the gravure roll 1. Have Due to this change in thickness, the surfaces 21a and 22a of the upper and lower holding plates 21 and 22 for holding the base end portions of the doctor blade 3 are formed as curved surfaces, and the doctor blade 3 sandwiched between the holding plates 21 and 22 is forcibly forced. Bending that is substantially the same as the bending in the direction perpendicular to the axis of the gravure roll 1 is imparted.

When the doctor blade 3 is forcibly bent by the metal blocks 23 and 24 and the pressing plates 21 and 22 as in the examples of FIGS. 10 and 11, the structure is simple.
The doctor blade 3 can be stably and accurately bent. Then, by preparing a plurality of types of the metal blocks 23, 24 and the holding plates 21, 22 in advance, it is possible to select and use an appropriate metal block or holding plate according to the target bending curve of the doctor blade 3. The desired deflection curve can be easily obtained.

In this way, when the doctor blade 3 is preliminarily provided with a deflection equivalent to the deflection of the gravure roll 1 by the deflection imparting means such as the vertical movement mechanism 33, the metal blocks 23 and 24, and the pressing plates 21 and 22, the doctor blade 3 3 from the initial stage of assembling, the contact end 3a of the doctor blade 3 on the surface of the gravure roll 1 which is bent by its own weight or the like.
Can be pressed uniformly along the roll axis direction. Therefore, the amount of the coating liquid on the surface of the gravure roll can be uniformly controlled in the roll width direction.
It is possible to make the distribution of the coating amount uniform with respect to. In addition, since the doctor blade 3 can be pressed uniformly against the surface of the gravure roll 1 from the initial stage of newly incorporating the doctor blade 3 without requiring a long run-in operation, the productivity can be improved. it can.

In the case of the gravure coating apparatus 100, the effectiveness can be particularly exhibited when the diameter of the gravure roll 1 is φ15 mm or more. For example, when the diameter of the gravure roll 1 is less than φ15 mm, pressing the doctor blade 3 against the gravure roll 1 causes the flexure of the gravure roll 1 to become too large and eccentric, resulting in periodic coating unevenness due to rotation of the gravure roll 1. May occur. Therefore, when the diameter of the gravure roll 1 is 15 mm or more, the effect of uniformizing the coating amount in the film base width direction (gravure roll axial direction) by the gravure coating method of the present invention is particularly remarkable.

Also, the gravure roll 1 plate (mesh)
There are various shapes such as diagonal lines (diagonal cups), lattices (trapezoidal cups) and pyramids (pyramid cups), but the above effect can be expected regardless of the shape of the plate. Also,
Regarding the size of the mesh, for example, the number of grooves per 25.4 mm (1 inch) can be freely selected within the range of 60 to 1500. If the mesh is too coarse, the coating amount increases, and the coating amount distribution in the width direction becomes relatively small. However, the effect of the present invention is not lost because the mesh is basically too fine.

The material of the doctor blade 3 is metal such as SK material (carbon tool steel JIS G 440).
Any of 1), Swedish steel, and resins such as polypropylene can be used. If made of metal,
By exhibiting sufficient abrasion resistance and high rigidity, the scraping property of the excess coating liquid becomes good,
A highly accurate coating amount distribution can be stably ensured. Further, when it is made of resin, there is no possibility of damaging the gravure roll.

Further, the contact between the doctor blade 3 and the gravure roll 1 is such that the tangent to the roll surface at the contact point with the gravure roll 1 and the crossing angle of the doctor blade are 4 degrees.
It is preferably 5 ° or less, and in this case, good scraping property can be obtained.

The gravure roll 1 is basically made of metal. However, as a ceramic gravure roll in which the surface of the metal roll is covered with a ceramic coating for preventing wear and a mesh (mesh) is formed on the surface. Good.

The film base 4 may be in the form of a sheet,
It may be a strip-shaped continuous film or a paper base. The width of the film base used is about 3 m at maximum, and the thickness is 5 to 5.
The thickness of 300 μm is preferable, but it is not limited thereto.

Further, as the film base 4, a preferable one is appropriately selected according to its use, and specifically, a transparent support is used. As the transparent support, it is preferable to use a plastic film. As the polymer forming the plastic film, cellulose ester (eg, triacetyl cellulose, diacetyl cellulose), polyamide, polycarbonate, polyester (eg, polyethylene terephthalate, polyethylene naphthalate),
Examples include polystyrene and polyolefin.

The coating solution is not particularly limited, but if the solid content concentration is 0.01 to 50% by weight, the viscosity is 0.1 to 30 cP, and the coating amount is 30 cc / m ² or less, the effect of the present invention can be easily obtained. It may be water-based or organic solvent-based. As the aqueous binder, any binder such as gelatin or PVA that dissolves in water and forms a film after drying may be used. The solvent-based binder may be a monomer or a polymer,
For example, in the case of a monomer, a monomer having two or more ethylenically unsaturated groups, an ester of a polyhydric alcohol and (meth) acrylic acid (eg, ethylene glycol di (meth) acrylate, 1,4-cyclohexanediacrylate, pentaerythritol) Tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolethane tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, Dipentaerythritol hexa (meth) acrylate, 1,2,3-cyclohexanetetramethacrylate, polyurethane polyacrylate, polyester polyacrylate), vinylbenzene and its Derivatives (eg 1,4-divinylbenzene, 4-vinylbenzoic acid-2-acryloylethyl ester, 1,4-divinylcyclohexanone), vinyl sulfone (eg divinyl sulfone), acrylamide (eg methylenebisacrylamide) and methacryl Includes amide.

Further, a crosslinkable group may be introduced instead of or in addition to the monomer having two or more ethylenically unsaturated groups. Examples of the crosslinkable functional group include an isocyanate group, an epoxy group, an aziridine group, an oxazoline group, an aldehyde group, a carbonyl group, a hydrazine group, a carboxyl group, a methylol group and an active methylene group. Vinyl sulfonic acid, acid anhydride, cyanoacrylate derivative,
Melamine, etherified methylol, esters and urethanes, metal alkoxides such as tetramethoxysilane,
There may be a block isocyanate group. When using a compound having such a cross-linking group, it is necessary to cross-link by heat after coating. Other examples include bis (4-methacryloylthiophenyl) sulfide, vinylnaphthalene, vinylphenyl sulfide, 4-methacryloxyphenyl-4′-methoxyphenylthioether and the like.

Further, the following inorganic ultrafine particles can be added.

Ultrafine particles of oxides of titanium, aluminum, indium, zinc, tin, antimony and zirconium and having a particle size of 100 nm or less, preferably 50 nm or less. Examples of such ultrafine particles include Ti
O ₂ , Al ₂ O ₃ , In ₂ O ₃ , ZnO, SnO ₂ , S
_{b 2 O 2, ITO, ZrO} 2 and the like.

The content of the fine particles in the binder is preferably 10 to 90% by weight based on the total weight of the coating liquid,
It is more preferably 20 to 80% by weight.

Examples of other binders include crosslinkable fluoropolymer compounds, such as perfluoroalkyl group-containing silane compounds (eg (heptadecafluoro-1,
In addition to 1,2,2-tetradecyl) triethoxysilane) and the like, a fluorine-containing copolymer containing a fluorine-containing monomer component and a monomer component for imparting a crosslinkable group as constituent components can be mentioned.

Specific examples of the above-mentioned fluorine-containing monomer component include, for example, fluoroolefins (for example, fluoroethylene, vinylidene fluoride, tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, perfluoro-2,2-dimethyl-1, 3-dioxole, etc., partially or fully fluorinated alkyl ester derivatives of (meth) acrylic acid (eg, biscoat 6FM)
(Osaka Organic Chemicals) and M-2020 (Daikin)
Etc.), fully or partially fluorinated vinyl ethers and the like.

As a monomer component for imparting a crosslinkable group, in addition to a (meth) acrylate monomer having a crosslinkable functional group in the molecule in advance such as glycidyl methacrylate,
Examples thereof include (meth) acrylate monomers having a carboxyl group, a hydroxyl group, an amino group, a sulfonic acid group, etc. (for example, (meth) acrylic acid, methylol (meth) acrylate, hydroxyalkyl (meth) acrylate, allyl acrylate, etc.). It is known in JP-A-10-25388 and JP-A-10-147739 that the latter can introduce a crosslinked structure after copolymerization.

Further, not only a polymer having the above-mentioned fluorine-containing monomer as a constituent unit, but also a copolymer with a monomer not containing a fluorine atom may be used.

The monomer units that can be used in combination are not particularly limited, and examples thereof include olefins (ethylene, propylene, isoprene, vinyl chloride, vinylidene chloride, etc.), acrylic acid esters (methyl acrylate, ethyl acrylate, acrylic acid 2- Ethylhexyl), methacrylic acid esters (methyl methacrylate, ethyl methacrylate, butyl methacrylate, ethylene glycol dimethacrylate, etc.), styrene derivatives (styrene, divinylbenzene,
Vinyltoluene, α-methylstyrene, etc.), vinyl ethers (methyl vinyl ether, etc.), vinyl esters (vinyl acetate, vinyl propionate, vinyl cinnamate, etc.), acrylamides (N-tert butyl acrylamide, N-cyclohexyl acrylamide, etc.) , Methacrylamides, acrylonitrile derivatives and the like.

Alcohols and ketones are mainly used as the solvent. As alcohols, methanol, ethanol,
Propanol, isopropanol, butanol, etc. are mainly used. As the ketone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, etc. are mainly used. Others such as toluene and acetone are also used. These may be used alone or in a mixture.

The gravure coating apparatus 10 of this embodiment
In 0, the doctor blade 3 is provided with a bending equivalent to the bending that occurs in the gravure roll 1, but the present invention is not limited to this, and even if the doctor blade 3 is pressed in a straight line, Even if the contact end of the front end of the doctor blade 3 is formed in a curved shape, the doctor blade 3 can be applied in the same manner, and the effect of uniforming the coating amount on the gravure roll can be obtained.

[0076]

EXAMPLES Next, the measurement results of the coating amount distribution in the width direction of the film base when the acrylic resin type coating liquid is gravure coated on the film base will be described.

As the film base, a polyethylene terephthalate film (Lumirror 100 μm, manufactured by Toray Industries, Inc.) was used, and widths of 500 mm and 1500 mm were prepared. Also, as a gravure roll, the roll diameter is φ40 mm, φ50 mm, φ200 mm, 25.4 m.
60,10 mesh grooves per m (1 inch)
The thing of 0,150,200 was prepared. Furthermore, as a doctor blade, the blade tip angle α is 10 °, 3
The ones of 0 °, 35 ° and 50 ° were prepared.

In the comparative example, the distribution range of the inclination length of the inclined surface of the doctor blade in the width direction of the gravure roll exceeds 30%, or the tangent line between the inclined surface of the doctor blade and the surface of the gravure roll contacting the surface of the gravure roll. It was set under the condition that the intersection angle θ with and exceeds ± 5 °.

In the embodiment according to the present invention, the distribution range of the inclination length of the inclined surface of the doctor blade is within 30%, and the waviness of the doctor blade alone in the gravure roll width direction is less than 50 μm. The intersection angle θ between the inclined surface of the doctor blade contacting the gravure roll surface and the tangent to the gravure roll surface was set within ± 5 °. In each case, the coating width is set to -10 mm to -50 mm with respect to the width of the film base.

The measurement results of each Example and Comparative Example are shown in Table 1 below.
Shown in. In each of the examples and the comparative examples, the evaluation at the start of coating is that ⊚ is uniform, ∘ is a little difficult but there is no problem, Δ is partly uneven streaks, and x is unevenness on the entire surface.

[0081]

[Table 1] As in Examples 1 to 6, the distribution range of the inclination length of the inclined surface of the doctor blade 3 in the gravure roll width direction is 30%.
And the straightness of the doctor blade 3 is less than 50 μm in the waviness in the gravure roll width direction, and
If the angle of intersection θ between the inclined surface of the doctor blade that contacts the gravure roll surface and the tangent to the gravure roll surface is within ± 5 °, even if the tip angle β of the inclined surface of the doctor blade is reduced to 10 ° Immediately after the start of use of the doctor blade, the coating amount distribution in the width direction of the gravure roll was stably made uniform, and good results were obtained in which the change with time was small as seen in the coating amount distribution after 8 hours of continuous coating.

On the other hand, as in Comparative Examples 1, 2, 3, 5, 7, and 8, when the distribution range of the inclination length of the inclined surface of the doctor blade in the width direction of the gravure roll exceeds 30%, or in Comparative Examples. When the angle of intersection θ between the inclined surface of the doctor blade contacting the gravure roll surface and the tangent line of the gravure roll surface exceeds ± 5 °, as in 4, 6, 8 part or all of the coating surface Streaks and the like occurred, which resulted in unbearable practical use. Further, when the waviness of the blade in the width direction is 50 μm or more, a good coating state cannot be obtained.

As described above, the larger the distribution range of the inclination length of the inclined surface of the doctor blade tip and the larger the intersection angle between the inclined surface of the blade tip and the tangent line of the gravure roll, the larger the coating amount distribution. However, if the distribution range of the inclination length is within 30% and the crossing angle θ is within ± 5 °, the distribution range of the coating amount can be reduced and the change of the coating amount distribution with time can be reduced.

[0084]

As described above, according to the doctor blade for gravure coating and the gravure coating method of the present invention, coating can be performed with a uniform coating amount immediately after the start of use of the doctor blade, and the variation of the coating amount distribution with time. It is possible to reduce the occurrence of streaks and unevenness on the coated surface. As a result, it is not necessary to lengthen the run-in from the initial stage when a new doctor blade is installed, and productivity can be improved.

[Brief description of drawings]

1A and 1B are explanatory views of a gravure coating method according to an embodiment of the present invention, in which FIG. 1A is a perspective view exaggerating flexure and FIG. 1B is I _b.
FIG.

FIG. 2A is a perspective view of a doctor blade, and FIG. 2B is an explanatory view showing a distribution (b) of the inclination length of the inclined surface of the tip portion with respect to the blade longitudinal direction and a waviness (c) of the blade.

FIG. 3 is an explanatory diagram in which a front end portion of a doctor blade is enlarged.

FIG. 4 is an explanatory view showing a state of a position where a doctor blade is pressed against a gravure roll.

FIG. 5 is an explanatory diagram showing how to obtain the deflection of the gravure roll when the gravure coating method is performed.

FIG. 6 is an explanatory diagram of conditions used for calculation of deflection of a gravure roll.

FIG. 7 is a side view of a blade holder used in the gravure coating device.

FIG. 8 is a perspective view showing a state in which a doctor blade held by a blade holder is pressed against a gravure roll.

FIG. 9 is an explanatory diagram showing an example of a method of bending a doctor blade in a gravure coating apparatus.

FIG. 10 is an explanatory diagram showing an example of another method of bending a doctor blade by a blade holder.

FIG. 11 is an explanatory view showing an example of another method of bending the doctor blade by the pressing plate.

FIG. 12 is an explanatory diagram of a gravure coating method and apparatus.

FIG. 13 is a configuration diagram of a main part of a coating device by direct gravure coating.

[Explanation of symbols]

1 gravure roll 2 coating liquid 3 doctor blade 3b inclined surface 4 film base Lb slope length θ crossing angle

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tomonari Ogawa             200, Onakazato, Fujinomiya City, Shizuoka Prefecture Fuji Photo             Within Film Co., Ltd. (72) Inventor Takayuki Nakanishi             No. 3 Soba Town, Shizuoka City, Shizuoka Prefecture             Tomagawa Paper Mill Business Headquarters F-term (reference) 4D075 AC25 AC34 AC93 CA48 DA04                       DB33 DB36 DB48 DB53 DB55                       EA05 EA10 EB16 EB19 EB20                       EB22 EB38 EB39 EB56                 4F040 AA22 AA31 AB04 AC01 BA26                       CB06 CB33 CB38                 4F042 AA22 AB00 BA06 BA10 BA25                       BA27 CA03 DD07 DD17

Claims (6)

[Claims] 1. A doctor blade for gravure coating, which presses the surplus coating solution on the surface of the gravure roll by pressing it across the width of the gravure roll to which the coating solution is supplied, the doctor for gravure coating The blade has an inclined surface at the tip end on the side to be pressed against the gravure roll, and the distribution range of the inclined surface length of the inclined surface in the width direction is within 30% of the specified inclined surface length, and The doctor blade for gravure application, wherein the straightness of the doctor blade alone is less than 50 μm in terms of waviness in the width direction. 2. The doctor blade for gravure coating according to claim 1, wherein the blade has a plate thickness of 0.5 mm or less. 3. The doctor blade for gravure coating according to claim 1, wherein the tip angle of the inclined surface of the blade tip portion is in the range of 5 ° to 80 °. 4. A coating solution is supplied to the surface of the gravure roll,
A gravure coating method for coating a film base with the coating liquid in the cells of the gravure roll after scraping off the excess coating liquid on the gravure roll surface with a doctor blade pressed against the surface of the gravure roll. While using the doctor blade for gravure coating according to any one of paragraphs 3, the inclined surface of the tip of the doctor blade for gravure coating that contacts the gravure roll surface and the tangent line at the contact position on the gravure roll surface. A gravure coating method characterized by setting a crossing angle within ± 5 °. 5. The gravure coating method according to claim 4, wherein a gravure roll having a diameter of 15 mm or more is used. 6. The gravure coating method according to claim 4 or 5, wherein a gravure roll having a number of grooves per 25.4 mm (1 inch) of 60 to 1500 is used.