JP4355504B2 - Gravure coating method and apparatus - Google Patents

Description

【００４７】
表１はこの実験結果を示している。
塗布液を次のように調整した。
シクロヘキサン１０４．１ｇ、メチルエチルケトン６１．３ｇの混合溶媒に、エアディスパで撹拌しながら酸化ジルコニウム（粒径役３０ｎｍ）分散物含有ハードコード塗布液（商品名：ＫＺ−７９９１、ＪＳＲ（株）製）２１７．０ｇ、を添加し、さらにこの溶液に、平均粒径２μｍの架橋ポリスチレン粒子（商品名：ＳＸ−２００Ｈ、綜研化学（株）製）５ｇを添加して、高速デバイスにて５０００ｒｐｍで１時間撹拌、分散した後、孔径３０μｍのポリプロピレン製フィルタで濾過して塗布液を調製した。
厚さ８０μｍのＴＡＣフイルム（商品名：ＴＡＣ−ＴＤ８０Ｕ、富士写真フイルム（株）製）に、上記の塗布液を塗布し、１２０℃で乾燥の後、１６０Ｗ／ｃｍの空冷メタルハライドランプ（アイグラフィック（株）製）を用いて、照度４００ｍＷ／ｃｍ² 、照射量３００ｍＪ／ｃｍ²の紫外線を照射して塗布層を硬化させ、厚さ約１．５μｍの層（下層）を形成した。
表は表の上左から右にグラビアロールの外径、メッシュの大きさ、フィルムベースの走行速度（Ｖｂ）、とグラビアロール表面の回転速度（Ｖｇ）、その速度比（Ｖｂ／Ｖｇ）、グラビアロールの彫刻角度α、グラビアロールの彫刻模様（版目）が塗布面に出るか否か、を示している。表の縦は実験回数を示し、それぞれいずれかの要素の数値を変えて１８回実験している。
１）実験１〜３では、グラビア径５０ｍｍでメッシュ２００／インチ、Ｒが０．２８６のときのα（彫刻角度）を変えるとどうなるかを示している。αが４０度又は３０度のときは版目模様が出なかったが、αが５０度では版目模様が出た。
したがって、Ｒが０．２９前後ではαが４０度と５０度の間（例えば、４５度）にその境界があり、それ以下であればよいものと推察される。
【００４８】
２）実験４〜７では、グラビア径５０ｍｍでメッシュ１００、Ｒが１．０のときのαを変えるとどうなるかを示している。αが４０度又は３０度のときは版目模様が出たが、αが５０度では版目模様が出なかった。また、αが６５のときは版目模様が出た。
したがって、Ｒが１前後ではαが４０度と５０度の間（例えば、４５度）に下限が、またαが６０度にその上限があるものと推察される。
【００４９】
３）実験８〜１０では、グラビア径５０ｍｍでメッシュ１００、Ｒが３．０のときのαを変えるとどうなるかを示している。αが５０度のときは版目模様が出たが、αが６０度又は７０度では版目模様が出なかった。
したがって、Ｒが３前後ではαが６０度以上が良好であるものと推察される。
【００５０】
４）実験１〜１０ではグラビア径が５０ｍｍであったが、実験１１〜１８では、グラビア径１００ｍｍで、そのメッシュ１００のものを用い、Ｒを３種類選び、それぞれについてαを変えるとどうなるかを示している。
実験１１〜１３では、αが０．２８６のとき、αが４０度で版目模様が出なかったが、４５では版目模様が弱く出た。また、αが５０度では版目模様が出てしまった。
したがって、Ｒが０．２９前後ではαが４５度前後にその境界があるものと推察される。
【００５１】
５）実験１４〜１６では、グラビア径１００ｍｍでメッシュ２００、Ｒが０．６６７のときのαを変えるとどうなるかを示している。αが４０で版目模様が出たが、αが５０度では版目模様が出なかった。また、αが６５度では版目模様が出てしまった。
したがって、Ｒが０．６７前後ではαが４５〜６０度が適切であると推察される。
【００５２】
６）実験１７および１８では、グラビア径１００ｍｍでメッシュ１００、Ｒが２．５のときのαを変えるとどうなるかを示している。αが５０で版目模様が出たが、αが６０度では版目模様が出なかった。
したがって、Ｒが２．５前後ではαが６０度にその境界があるものと推察される。
【００５３】
以上のことから、おおよそ次のことが言える。
（１）Ｒ≦０．３の場合は、前記所定角度α≦４５度とし、
（２）０．３＜Ｒ≦２の場合は、４５＜α≦６０度とし、
（３）２＜Ｒの場合は、６０≦α、
とすることがよいことが判る。
【００５４】
また、グラビアロールについては、表１から、その外径が１５ｍｍ〜２５０ｍｍで、メッシュが♯１００〜１５００／インチであるのがよいと考えられる。
【００５５】
図９はロール円周方向に対して種々の彫刻角度αで平行に刻まれた多数の細い彫刻模様のグラビアロールを示す説明図で、（ａ）はα１＝８０度、（ｂ）はα２＝６０度、（ｃ）はα３＝４５度、（ｄ）はα４＝３０度、（ｅ）はα５＝２０度の平行溝をそれぞれ有するグラビアロールである。
本グラビア塗布装置では、このような種々のαを有するグラビアロールを多数用意しておき、フィルムベースの走行速度（Ｖｂ）とグラビアロール表面の回転速度（Ｖｇ）とからその速度比（Ｖｂ／Ｖｇ）Ｒを求め、その比Ｒが異なる毎に、上記関係を満たすグラビアロールを選んで用いるようにするとよい。
【００５６】
【発明の効果】
以上説明したように、グラビアロール１の表面にあるロール円周方向に対して所定の角度αで平行に刻まれた多数の細い彫刻模様がフィルムベースの走行速度（Ｖｂ）とグラビアロール表面の回転速度（Ｖｇ）との比（Ｖｂ／Ｖｇ）をＲとすると、
（１）Ｒ≦０．３の場合は、前記所定角度α≦４５度とし、
（２）０．３＜Ｒ≦２の場合は、４５＜α≦６０度とし、
（３）２＜Ｒの場合は、６０≦α、
とすることにより、塗布量１０ｃｃ／ｍ^２以下で塗布した時でもグラビアロールの彫刻模様の写りを塗布面に出ないようにすることができる。
【図面の簡単な説明】
【図１】グラビア塗布方法及び装置の説明図である。
【図２】従来のグラビア塗布方法の要部を示す概略説明図である。
【図３】従来のグラビア塗布方法の問題点を示す説明図である。
【図４】図３で示す問題点を模式的に示す説明図である。
【図５】従来の公知例によるブレードコーターの説明図である。
【図６】従来のブレードの当たり均一化対策を説明するための図である。
【図７】グラビアロールの軸支構造を示す説明図である。
【図８】ロール円周方向に対して所定の角度で平行に刻まれた多数の細い彫刻模様のグラビアロールを示す説明図である。
【図９】ロール円周方向に対して種々の角度で平行に刻まれた多数の細い彫刻模様のグラビアロールを示す説明図である。
【図１０】本発明の実施形態のグラビア塗布方法の説明図で、（ａ）は撓みを誇張して示す斜視図、（ｂ）は（ａ）図のＩｂ矢視図である。
【図１１】グラビア塗布方法を実施する際のグラビアロールの撓みの求め方を示す説明図である。
【図１２】グラビアロールの撓み計算に使用する条件の説明図である。
【図１３】グラビア塗布装置に使用するブレードホルダの側面図である。
【図１４】ドクターブレード先端部の拡大図である。
【図１５】グラビアロールにブレードホルダに狭持されたドクターブレードを押し当てている様子を示す斜視図である。
【符号の説明】
１ グラビアロール
２ 塗布液
３ ドクターブレード
３ａ 接触端
４ フィルムベース
５ 塗布液貯留部（塗布液供給部）
１１ グラビアロール表面に刻まれた彫刻斜線
２０，４０，５０ ブレードホルダ
２１，２２ 押え板
２１ａ，２２ａ 湾曲面
２３，２４ 金属ブロック
２３ａ，２４ａ 湾曲面
３３ 上下動機構（ホルダ撓み付与手段）
α グラビアロール表面に刻まれた彫刻斜線の円周方向に対する角度[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a gravure coating method and apparatus useful for applications that require a uniform coating amount distribution, and more particularly to a gravure roll having a number of thin engraving patterns parallel to each other on the surface.
[0002]
[Prior 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. 1, the surplus of the surface of the gravure roll 1 is supplied by a doctor blade 3 that supplies the coating liquid 2 to the surface of the gravure roll 1 that is rotationally driven and presses against the surface of the gravure roll 1. After scraping off the coating solution, the coating solution in the cell of the gravure roll 1 is applied onto the film base 4. The doctor blade 3 presses the surface of the gravure roll 1 after the coating liquid 2 is supplied from the coating liquid reservoir 5 to the surface of the gravure roll 1 until it contacts the film base 4. In addition, in FIG. 1, 6a-6c is a guide roll, 8 is a drying part, 90 is an ultraviolet irradiation type curing apparatus. Further, the film base 4 travels in the direction of the arrow Y1, and the gravure roll 1 rotates in the direction of the arrow Y2. This is called the “reverse” gravure coating method.
[0003]
In this case, as shown in FIG. 2, the doctor blade 3 presses the straight tip edge against the surface of the gravure roll 1, but actually, as shown in FIG. Due to the bending, a non-uniform gap 7 is formed in the roll width direction between the contact end 3a of the doctor blade 3 and the gravure roll 1 as schematically shown in FIG. Therefore, the scraping amount by the doctor blade 3 becomes non-uniform in the roll width direction due to the influence, and as a result, the distribution amount distribution in the width direction with respect to the film base 4 (see FIG. 1) becomes non-uniform.
[0004]
The effect is particularly prominent when the coating amount on the film base 4 is small. For example, when a coating liquid that constitutes an antireflection film of a liquid crystal display is applied on a film base, the coating amount is 10 cc / m. ² Since there are few below, the request | requirement for uniformity of coating amount (film thickness) distribution is especially severe, and the countermeasure for uniform coating amount becomes essential.
[0005]
Various methods for equalizing the coating amount in the width direction of the film base have been developed for each coating method. For example, Japanese Patent Application Laid-Open No. 6-55124 discloses a technique for bending the tip edge 11a of the blade 11 in accordance with the deflection of the backup roll 12, as shown in FIG.
However, even if the tip edge of the doctor blade in the case of gravure application is curved by applying the technique of the above publication, the object to be brought into contact with the doctor blade is a metal gravure roll, and film or paper in the case of a blade coater In contrast, since it does not have flexibility, it is difficult to uniformly apply the doctor blade to the gravure roll to make the coating amount distribution uniform.
[0006]
Therefore, in practice, as a measure for equalizing the coating amount, the doctor blade 3 is pressed against the rotating gravure roll 1 at the initial stage of assembly of the doctor blade 3 as shown in FIG. The tip edge of No. 3 was worn by the gravure roll 1, and the method of making both hits accustomed had to be taken. In the figure, 9 indicates a portion scraped off by the leveling operation. However, when the gravure roll 1 has a large deflection, it has to take a long time to operate the doctor blade 3 until the tip of the doctor blade 3 is sufficiently scraped, which has been a factor of greatly reducing productivity. .
[0007]
It is also conceivable to make the coating amount distribution uniform by making the gravure roll 1 itself difficult to bend. Specifically, as shown in FIG. 7, in the structure in which the gravure roll 1 is pivotally supported by fitting a journal portion 1 a formed at the end of the gravure roll to the bearing portion 10, the inter-bearing distance L <b> 1 of the gravure roll 1. The gravure roll 1 by means such as narrowing the diameter dj of the journal part 1a, increasing the distance L2 between the base end part of the journal part 1a and the bearing part 10, or increasing the diameter dG of the gravure roll 1. Can be suppressed. However, even if such various measures are taken, the bending of the gravure roll 1 cannot be completely eliminated. Therefore, the problem that the coating amount distribution becomes nonuniform due to the remaining bending amount cannot be solved. .
[0008]
In consideration of the above circumstances, even when the amount of gravure coating is extremely small, the distribution of the coating amount in the circumferential direction of the gravure roll can be made uniform immediately after the start of use of the doctor blade. There is a gravure coating method and apparatus that can obtain a good uniform coated surface even when applying a very small amount of gravure without requiring much operation, and can greatly reduce the coating time and improve productivity. It was sought after.
Therefore, in the gravure coating method according to the prior invention of the present applicant (see, for example, Patent Document 1), as will be described later, the gravure roll is supplied with a coating liquid, and gravure is applied by a doctor blade pressed against the gravure roll surface. A gravure coating method in which the coating liquid in the cell of the gravure roll is applied to the film base after scraping off the excess coating liquid on the roll surface, and the doctor blade has a deflection substantially equivalent to the axial vertical deflection of the gravure roll. The excess coating liquid is scraped off.
[0009]
[Patent Document 1]
Japanese Patent Application No. 2002-63792
[0010]
According to this gravure coating method, since the deflection equivalent to that of the gravure roll is preliminarily applied to the doctor blade, the doctor is applied to the surface of the gravure roll that has been bent by its own weight from the initial stage of assembly of the doctor blade. The contact end of the blade can be uniformly applied over the roll axis direction. Therefore, the amount of the coating liquid on the surface of the gravure roll can be controlled uniformly in the roll axis direction, and the coating amount distribution on the film base can be made uniform. In addition, since the doctor blade can be uniformly applied to the surface of the gravure roll from the initial stage when the doctor blade is newly installed, it is possible to improve the productivity even if the running time is not extended for a long time. .
[0011]
[Problems to be solved by the invention]
The gravure roll 1 plate (mesh) used in the gravure coating has various shapes such as diagonal lines (hatched cups), lattices (trapezoidal cups), pyramids (pyramid cups).
However, when the application amount is small by such a gravure application method, the paint applied on the base may form a pattern as in the gravure plate shape. In addition, when the coating film is formed thinly, the amount of paint held in each cell is reduced, so that the paint is more easily removed. As a result of various experiments, the gravure sculpture shape in gravure is a large number of slender sculpture patterns (saw-toothed cross section) engraved in parallel at a predetermined angle α with respect to the roll circumferential direction It turned out to be superior to other shapes. FIG. 8 shows an example of a gravure roll having a large number of thin engraving patterns carved in parallel. In this case, it has been found that the effect of the mesh size is also great in the range of, for example, # 50 to # 500 / inch.
[0012]
However, the wet coating amount is 10 cc / m. ² In the following, when a large number of gravure rolls engraved in parallel with the roll circumferential direction at a predetermined angle α are used, a sculpture pattern (platelet) appears on the coated surface. I found out. This plate pattern was more noticeable as the coating amount on the film base was smaller. In particular, it was found that when the coating solution contains fine particles, the fine particles are likely to be arranged in a sculpture pattern. In particular, when a liquid containing fine particles is applied on a film and the width of the sculpture pattern is several hundred μm, the sculpture pattern itself is difficult to see with the naked eye, but it is stacked on equipment with patterns of the same type. It was found that interference fringes are generated depending on the overlapping angle.
Therefore, the applicant has dealt with this by increasing the coating amount and increasing or decreasing the viscosity in proportion to the coating amount, but increasing the coating amount increases unevenness due to wind, drying load, and viscosity. When moving up and down, another problem has arisen, such as streaks being likely to occur, and the coating speed has to be reduced as a countermeasure.
[0013]
The object of the present invention has been made in consideration of the above-mentioned circumstances. ² It is to prevent the gravure roll sculpture pattern from appearing on the coated surface even when applied below.
[0014]
[Means for Solving the Problems]
To achieve the above purpose, Of the present invention The gravure coating method rotates a gravure roll having a mesh parallel to the roll circumferential direction at a predetermined angle α on the surface of the gravure roll. 0.1-20 cP containing particles with a particle size of 10 μm or less Scrape off the excess coating liquid on the surface of the gravure roll by a doctor blade that supplies the coating liquid and pressed against the surface of the gravure roll, Plastic film In a state where the gravure roll is pressed against the rotation direction of the gravure roll. Plastic film By running the coating liquid in the engraving pattern Plastic film Application amount 10cc / m ² In the gravure coating method applied below,
Above Plastic film When the traveling speed of Vb is Vb and the rotational speed of the gravure roll surface is Vg, the relationship between the ratio R = Vb / Vg and the predetermined angle α is any of the following (1) to (3) One A gravure coating method characterized by satisfying:
(1) When R ≦ 0.3, the predetermined angle α ≦ 45 degrees.
(2) If 0.3 <R ≦ 2, 45 <α ≦ 60 degrees
(3) If 2 <R, 60 ≦ α.
The gravure coating method further includes: The gravure roll has an outer diameter of 15 mm to 250 mm and a mesh of # 100 to 500 / inch.
Also, The invention of a gravure coating apparatus is a gravure roll for applying a coating liquid to a film base, and has a number of fine engraving patterns engraved on the surface at a predetermined angle α with respect to the roll circumferential direction, and The coating liquid supply unit that supplies the coating liquid to the surface of the gravure roll and the gravure roll surface scraped off the excess coating liquid by being pressed against the surface of the gravure roll from when the coating liquid is supplied until it contacts the film base A doctor blade; and a film base supply means for running the film base in a direction opposite to the rotation direction of the gravure roll, and the coating amount in the engraving pattern is applied to the film base at a rate of 10 cc / m. ² In the gravure coating apparatus to be applied below, the gravure roll is a gravure roll with the predetermined angle α ≦ 45 degrees, a gravure roll with 45 <α ≦ 60 degrees, ≦ It is characterized by comprising at least three types of gravure rolls of α.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, in the gravure coating method and apparatus to which the present invention is applied, first, the amount of coating liquid on the surface of the gravure roll can be controlled uniformly in the roll circumferential direction, and the coating amount distribution on the film base can be made uniform. The technique of the applicant's prior invention that can be achieved will be described with reference to the drawings.
FIG. 10 is an explanatory diagram showing the relationship between the gravure roll and the doctor blade. (A) is a perspective view, (b) is an Ib arrow view. Reference numeral 1 denotes a gravure roll targeted by the present invention, and 3 denotes a doctor blade which is handled by a prior invention. In FIG. 10, the coating liquid 2 (FIG. 1) is supplied to the surface of the gravure roll 1 rotatably supported between the bearings, and the surface of the gravure roll 1 is pressed by the doctor blade 3 pressed against the surface of the gravure roll 1. After scraping off the excess coating solution, the coating solution in the cell of the gravure roll 1 is applied to the film base 4 (FIG. 1). As shown in FIGS. 10 (a) and 10 (b), the deflection is exaggerated. The surplus coating liquid is scraped off by imparting to the doctor blade 3 a deflection substantially equivalent to the deflection in the direction perpendicular to the axis of the gravure roll 1.
[0016]
In this case, at least the contact end 3a with respect to the gravure roll 1 at the tip of the doctor blade 3 is surely placed on the surface of the gravure roll 1, in particular, on the same generatrix (the axial line of the roll surface in the state without roll deflection). It is only necessary that the doctor blade 3 be bent so as to come into contact. In addition, the Ib direction of FIG.10 (b) is a direction (substantially horizontal direction) orthogonal to the maximum bending direction (substantially vertical direction) of the gravure roll 1. FIG.
[0017]
Here, how to obtain the bending of the gravure roll 1 will be described with reference to FIG. First, the force that gives the gravure roll 1 deflection includes the vertical component of the tension T of the film base 4 that contacts the gravure roll 1, the vertical component of the pressing force PB of the doctor blade 3 against the gravure roll 1, and the gravure roll 1 's own weight. Exists. The doctor blade 3 is pressed against the surface of the point Q in the direction of the angle b1 with respect to the vertical line from the center of the gravure roll 1 with an inclination of the angle b2 formed with the horizontal line. However, each element is set so as to satisfy the following conditions.
[0018]
(A) Gravure roll's own weight> Doctor blade pressure
(B) 0 ° <b1 <90 °
(C) -45 ° <b2 <45 °
(D) a1 ≦ 30 °, a2 ≦ 30 °
[0019]
That is, according to (a), since the pressing force of the doctor blade is smaller than the gravure roll's own weight, the horizontal component of the pressing force of the doctor blade becomes sufficiently small. Further, according to (b), the angle b1 can be set in a range where the horizontal force by the doctor blade does not increase and the scraping performance of the blade is good, and according to (c), the pressure of the doctor blade is reduced. The horizontal component can be made smaller than the vertical component. And according to (d), the horizontal component by the tension | tensile_strength of a film base can be made small. Therefore, by satisfying the above conditions (a) to (d), the horizontal force acting on the gravure roll becomes sufficiently small with respect to the vertical force, and only the vertical force is taken into consideration. Even if the deflection is calculated, it is at a level where there is substantially no problem. In addition, if the film base has a relationship of a1> a2, the generated horizontal component force is generated in a direction opposite to the horizontal component force caused by the pressing force of the doctor blade. The force to do is almost offset. Even if there is a force in the horizontal direction that cannot be ignored, for example, the blade shape shown in FIG. 16 described in JP-A-6-55124 can provide a uniform pressing state along the gravure roll axis direction. As a result, the coating amount distribution is made uniform.
[0020]
Now, the maximum bending of the gravure roll 1 occurs in the vertical direction in the vertical direction of the axis, and the bending in the horizontal direction is considered negligible, and attention is paid only to the force in the vertical direction. Since the gravity 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 due to the tension T of the film base 4 is expressed by the equation (1).
[0021]
A = Tsina1 + Tsina2 (1)
However, a1 is an angle made with the horizontal line on the entrance side of the film base 4, and a2 is an angle made with the horizontal line on the exit side of the film base 4. Further, the vertical component force B of the pressing force PB of the doctor blade 3 against the gravure roll 1 is expressed by the equation (2).
[0022]
B = PBcosb2 (2)
Since the resultant force of these A, B, and C acts in the vertical direction, the force P in the vertical direction is
P = A + B + C (3)
Then, the bending in the vertical direction, which is the axis-perpendicular direction, of the gravure roll 1 is obtained by Equation (4) as the bending due to the equal load on the both-end support beams shown in FIG.
[0023]
Deflection = {L4P / (2EI)}
[1/2 · {(Lx) / L} 2-11 / 12 · {(Lx) / L} 4]
... (4)
However,
P: Force that gives deflection to the gravure roll (equal load)
E: Longitudinal elastic modulus of gravure roll
I: Sectional moment of gravure roll
L: Gravure roll surface length (distance between bearings) / 2
x: Distance from center point in gravure roll axial direction
[0024]
Therefore, a deflection substantially equivalent to the deflection generated in the gravure roll 1 is applied to the doctor blade 3 based on the equation (4). Thereby, the contact end 3a of the doctor blade 3 is uniformly applied along the roll axial direction to the surface of the gravure roll 1 in a state of being bent by its own weight or the like from the initial stage of assembly of the doctor blade 3. 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. It can apply | coat uniformly over the width direction of the film base 4. FIG. In addition, from the initial stage when the doctor blade 3 is newly incorporated, it is not necessary to perform a break-in operation for a long time, and productivity can be improved.
[0025]
The deflection amount distribution of the above formula (4) to be applied to the doctor blade 3 is not limited to this, and the deflection amount distribution can be set by approximating it with a quadratic or cubic curve. The effect of. Further, the bending imparted to the doctor blade 3 may be plastic deformation of the doctor blade 3 in advance so as to draw the same curve as the bending amount obtained from the calculation, in addition to the bending by the external force described above. That is, in this specification, the bending imparted to the doctor blade 3 includes both those imparted by elastic deformation and those imparted by plastic deformation. Further, even if the bending of the gravure roll 3 is substantially equal to the bending curve obtained, there is substantially no problem as long as it is within an error range of ± 30%.
[0026]
Next, a gravure coating apparatus for realizing the gravure coating method will be described in detail.
As shown in FIG. 1, the gravure coating apparatus 100 is a gravure roll 1 that is rotationally driven by a driving means (not shown) to apply a coating liquid 2 to a film base 4 and a coating that supplies the coating liquid 2 to the surface of the gravure roll 1. The surplus coating liquid on the surface of the gravure roll 1 is scraped by being pressed against the surface of the gravure roll 1 from when the liquid supply part (coating liquid storage part 5) is supplied to the film base 4 after the coating liquid 2 is supplied. A doctor blade 3 to be dropped is provided, and as shown in FIG. 1, at least the contact end 3 a of the doctor blade 3 with respect to the gravure roll 1 is given a deflection substantially equivalent to the axial vertical deflection of the gravure roll 1.
[0027]
The gravure coating apparatus 100 includes a blade holder as means for holding the doctor blade 3. FIG. 13 shows a cross-sectional view of the blade holder. The blade holder 20 includes two pressing plates 21 and 22 that sandwich the proximal end portion of the doctor blade 3, and two metal blocks 23 that exert a clamping force on the doctor blade 3 through the two pressing plates 21 and 22. 24 and fastening bolts 25 and nuts 26 for fastening the metal blocks 23 and 24 to each other. Instead of the fastening bolt 25 and the nut 26, it is possible to obtain a clamping force (a clamping force with respect to the presser plate) with fluid pressure, and the type for obtaining the clamping force of the doctor blade 3 is not particularly limited.
[0028]
The length Lb of the doctor blade 3 protruding from the presser plate 21 of the blade holder 20 is set to 1 mm to 50 mm, preferably 3 mm to 20 mm, so that the bending curved surface in the blade longitudinal direction set on the blade holder 20 side is obtained. It 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 blade length in the longitudinal direction is larger, and is set to 30 to 200 mm in order to ensure handling. As shown in the enlarged view of the blade tip portion in FIG. 14, the doctor blade 3 has a tip angle set to an acute angle of about 5 ° to 80 °, and the tangent line of the gravure roll surface to be pressed against the inclined surface 3b of the blade tip portion. The angle is set to ± 5 ° or less. As a result, the inclined surface 3b at the blade tip and the gravure roll surface are pressed flat against each other, and the coating liquid can be stably coated immediately after the start of coating. Further, the plate thickness t of the doctor blade 3 is 0.05 mm to 0.5 mm, preferably 0.05 mm to 0.3 mm, and those having appropriate rigidity and flexibility are appropriately used. The presser plates 21 and 22 have a thickness of 0.3 mm to 3 mm.
[0029]
In this gravure coating apparatus 100, the blade holder 20 itself is bent to give the doctor blade 3 the same bending as the gravure roll 1. That is, as shown in FIG. 15 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 bodies 31 and 31 so that the entire blade holder 20 is The central portion bends in the vertical direction over the longitudinal direction. The blade holder 20 is bent downward (in some cases upward) by applying an external force to the central portion by a vertical movement mechanism 33 as a holder bending imparting means, whereby the doctor blade 3 sandwiched by the blade holder 20 The gravure roll 1 is bent substantially in the same direction as the axial vertical direction. The weight of the blade holder 20 itself is also considered as a part of the external force here. The point of action for applying the external force is not limited to one place in the central portion of the blade holder 20 in the longitudinal direction, but may be provided at a plurality of places at predetermined intervals to set the bending shape more precisely. As the vertical movement mechanism 33, an arbitrary type such as a screw type or a fluid pressure type can be adopted.
[0030]
Although not shown in the drawing, the blade holder 20 has a mechanism for attaching and detaching the doctor blade 3 to and from the gravure roll 1. For example, the blade holder 20 is moved back and forth by an air cylinder, and the doctor blade 3 is moved. It is the structure which can perform separation operation | movement from the surface of the gravure roll, and contact operation.
[0031]
As described above, 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.
[0032]
The doctor blade 3 may be made of any material such as metal, for example, SK material (carbon tool steel JIS G 4401), or polypropylene. When it is made of metal, it can exhibit sufficient wear resistance and high rigidity, so that the scraping property of the surplus coating liquid becomes good, and a highly accurate coating amount distribution can be secured stably. Moreover, when comprised with resin, there is no possibility of scratching the gravure roll.
Further, the contact of the doctor blade 3 with the gravure roll 1 is preferably such that the angle of intersection between the tangent at the contact point with the gravure roll 1 and the doctor blade is 45 ° or less, and in this case, good scraping properties are obtained. It is done.
[0033]
The gravure roll 1 is basically made of metal, but may be a ceramic gravure roll in which the surface of the metal roll is covered with a ceramic coating for preventing wear and a plate (mesh) is formed on the surface.
The film base 4 may be in the form of a sheet, or may be a strip-like continuous film or a paper base. For example, the maximum width of the film base to be used is about 3 m and the thickness is preferably 5 to 300 μm, but is not limited thereto.
[0034]
The film base 4 is appropriately selected depending on its use, and specifically, a transparent support is used. As the transparent support, it is preferable to use a plastic film. Examples of the polymer forming the plastic film include cellulose ester (eg, triacetyl cellulose, diacetyl cellulose), polyamide, polycarbonate, polyester (eg, polyethylene terephthalate, polyethylene naphthalate), polystyrene, and polyolefin.
[0035]
The coating solution is not particularly limited, but has a solid content concentration of 0.01 to 80% by weight, a viscosity of 0.1 to 20 cP, and a coating amount of 10 cc / m. ² It may be as follows, and may be water-based or organic solvent-based. Any aqueous binder may be used as long as it dissolves in water such as gelatin or PVA and forms a film after drying. 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, dipenta Erythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,2,3-cyclohexanetetramethacrylate, polyurethane poly Acrylate, 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 methacrylamide.
[0036]
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. There may be vinyl sulfonic acid, acid anhydride, cyanoacrylate derivative, melamine, etherified methylol, ester and urethane, metal alkoxide such as tetramethoxysilane, and block isocyanate group. When using these compounds having a crosslinking group, it is necessary to crosslink by application of heat or the like. Other examples include bis (4-methacryloylthiophenyl) sulfide, vinyl naphthalene, vinyl phenyl sulfide, 4-methacryloxyphenyl-4′-methoxyphenyl thioether, and the like.
[0037]
In addition, inorganic ultrafine particles, organic and inorganic fine particles, a photoreaction initiator, a surfactant, and the like may be included. The inorganic ultrafine particles are ultrafine particles having a particle diameter of 100 nm or less, preferably 50 nm or less, composed of oxides of titanium, aluminum, indium, zinc, tin, antimony and zirconium. Examples of such ultrafine particles include TiO2, Al2O3, In2O3, ZnO, SnO2, Sb2O2, ITO and ZrO2.
The content of the inorganic ultrafine particles in the binder is preferably 10 to 90% by weight, more preferably 20 to 80% by weight, based on the total weight of the coating solution.
[0038]
In addition, inorganic fine particles or polymer fine particles having a particle diameter of 10 μm or less may be added to the coating solution. Inorganic fine particles include silica beads. Examples of the polymer fine particles include polymethyl methacrylate acrylate beads, polycarbonate beads, polystyrene beads, polyacryl styrene beads, and silicone beads.
[0039]
Examples of other binders include cross-linkable fluoropolymer compounds, and other than perfluoroalkyl group-containing silane compounds (for example, (heptadecafluoro-1,1,2,2-tetradecyl) triethoxysilane), Examples thereof include a fluorine-containing copolymer having a fluorine-containing monomer component and a monomer component for imparting a crosslinkable group as constituent components.
[0040]
Specific examples of the fluorine-containing monomer component include, for example, fluoroolefins (for example, fluoroethylene, vinylidene fluoride, tetrafluoroethylene, hexafluoroethylene, hexafluoropropylene, perfluoro-2,2-dimethyl-1,3-dioxole) Etc.), (meth) acrylic acid partial or fully fluorinated alkyl ester derivatives (for example, Biscoat 6FM (manufactured by Osaka Organic Chemical Co., Ltd.) and M-2020 (manufactured by Daikin)), fully or partially fluorinated vinyl ethers and the like.
[0041]
The monomer component for imparting a crosslinkable group has a carboxyl group, a hydroxyl group, an amino group, a sulfonic acid group, etc. in addition to a (meth) acrylate monomer having a crosslinkable functional group in advance in the molecule like glycidyl methacrylate And (meth) acrylate monomers (for example, (meth) acrylic acid, methylol (meth) acrylate, hydroxyalkyl (meth) acrylate, allyl acrylate, etc.). It is known from JP-A-10-25388 and JP-A-10-147739 that the latter can introduce a crosslinked structure after copolymerization.
[0042]
Further, not only a polymer having the above-mentioned fluorine-containing monomer as a structural unit but also a copolymer with a monomer not containing a fluorine atom may be used.
[0043]
There are no particular limitations on the monomer units that can be used in combination, such as olefins (ethylene, propylene, isoprene, vinyl chloride, vinylidene chloride, etc.), acrylic esters (methyl acrylate, ethyl acrylate, 2-ethylhexyl acrylate), Methacrylic esters (methyl methacrylate, ethyl methacrylate, butyl methacrylate, ethylene glycol dimethacrylate, etc.), styrene derivatives (styrene, divinylbenzene, vinyl toluene, α-methylstyrene, etc.), vinyl ethers (methyl vinyl ether, etc.), Vinyl esters (vinyl acetate, vinyl propionate, vinyl cinnamate, etc.), acrylamides (N-tertbutylacrylamide, N-cyclohexylacrylamide, etc.), methacrylamides, acrylonitrile derivatives Mention may be made of the body or the like.
[0044]
As the solvent, alcohols and ketones are mainly used, and methanol, ethanol, propanol, isopropanol, butanol and the like are mainly used as alcohols. As the ketone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone and the like are mainly used. In other cases, toluene, acetone or the like is used. These may be used alone or mixed and used.
[0045]
Next, in the gravure coating method which is the object of the present invention, the coating amount is 10 cc / m. ² A method for preventing the gravure roll engraving pattern from appearing on the coated surface even when applied below will be described.
As described with reference to the gravure roll of FIG. 8, the surface of the gravure roll 1 is engraved with a large number of thin engraving patterns that are engraved in parallel with the roll circumferential direction at a predetermined angle α. The cross section of the sculpture pattern has a saw blade shape. Until now, the predetermined angle α seemed to be optimal around 45 degrees.
However, as a result of various examinations by the applicant, it has been found that this is not always the case. That is, the coating liquid is supplied to the surface of the gravure roll as in the present invention, the excess coating liquid on the surface of the gravure roll is scraped off by a doctor blade, and the rotation direction of the gravure roll is reversed with the film base pressed against the gravure roll. The film base travels in the direction of the coating, and the coating liquid in the engraving pattern is applied to the film base at 10 cc / m. ² In the case of application below, depending on the angle α, the speed of the traveling base, and the rotation speed of the gravure roll, the gravure roll image may or may not appear on the coated surface.
As a result of various experiments, the present applicant has found that the following relationship exists between the running speed (Vb) of the film base and the rotational speed (Vg) of the gravure roll surface. That is, when the speed ratio (Vb / Vg) is R,
(1) When R ≦ 0.3, the predetermined angle α ≦ 45 degrees,
(2) If 0.3 <R ≦ 2, 45 <α ≦ 60 degrees,
(3) If 2 <R, 60 ≦ α,
It is good to do.
[0046]
[Table 1]

[0047]
Table 1 shows the results of this experiment.
The coating solution was adjusted as follows.
A hard cord coating solution containing a dispersion of zirconium oxide (particle size: 30 nm) in a mixed solvent of 104.1 g of cyclohexane and 61.3 g of methyl ethyl ketone while stirring with an air disperser (trade name: KZ-7991, manufactured by JSR Corporation) In addition, 5 g of a crosslinked polystyrene particle having an average particle diameter of 2 μm (trade name: SX-200H, manufactured by Soken Chemical Co., Ltd.) was added to this solution, and the mixture was stirred at 5000 rpm for 1 hour with a high-speed device. After dispersion, the solution was filtered through a polypropylene filter having a pore size of 30 μm to prepare a coating solution.
The above coating solution was applied to a TAC film (trade name: TAC-TD80U, manufactured by Fuji Photo Film Co., Ltd.) having a thickness of 80 μm, dried at 120 ° C., and then a 160 W / cm air-cooled metal halide lamp (eye graphic ( Illuminance 400 mW / cm ² , Irradiation amount 300mJ / cm ² Was applied to cure the coating layer to form a layer (lower layer) having a thickness of about 1.5 μm.
The table shows the gravure roll outer diameter, mesh size, film base running speed (Vb), gravure roll surface rotation speed (Vg), speed ratio (Vb / Vg), gravure It indicates whether the engraving angle α of the roll and the gravure roll engraving pattern (printed surface) appear on the coating surface. The vertical column of the table shows the number of experiments, and each experiment is performed 18 times with different numerical values.
1) Experiments 1 to 3 show what happens when α (engraving angle) is changed when the gravure diameter is 50 mm, the mesh is 200 / inch, and R is 0.286. When α was 40 degrees or 30 degrees, no print pattern appeared, but when α was 50 degrees, a print pattern appeared.
Therefore, when R is around 0.29, α has a boundary between 40 degrees and 50 degrees (for example, 45 degrees), and it is presumed that it may be less than that.
[0048]
2) Experiments 4 to 7 show what happens when α is changed when the gravure diameter is 50 mm and the mesh 100 and R is 1.0. When α was 40 degrees or 30 degrees, a print pattern appeared, but when α was 50 degrees, a print pattern did not appear. Further, when α was 65, a print pattern appeared.
Therefore, when R is around 1, it is assumed that α has a lower limit between 40 degrees and 50 degrees (for example, 45 degrees), and α has an upper limit at 60 degrees.
[0049]
3) Experiments 8 to 10 show what happens when α is changed when the gravure diameter is 50 mm and the mesh 100 and R is 3.0. When α was 50 °, a print pattern appeared, but when α was 60 ° or 70 °, no print pattern appeared.
Therefore, it is presumed that when R is around 3, α is 60 ° or more.
[0050]
4) In Experiments 1-10, the gravure diameter was 50 mm. In Experiments 11-18, the gravure diameter was 100 mm, the mesh 100 was used, three types of R were selected, and what happens when α was changed for each. Show.
In Experiments 11 to 13, when α was 0.286, α was 40 degrees and no print pattern appeared, but at 45, the print pattern was weak. In addition, when α was 50 degrees, a print pattern appeared.
Therefore, when R is around 0.29, it is assumed that α has a boundary around 45 degrees.
[0051]
5) Experiments 14 to 16 show what happens when α is changed when the gravure diameter is 100 mm and the mesh 200 and R is 0.667. A print pattern appeared when α was 40, but no print pattern appeared when α was 50 degrees. In addition, when α was 65 degrees, a print pattern appeared.
Therefore, when R is around 0.67, it is inferred that α is appropriately 45 to 60 degrees.
[0052]
6) Experiments 17 and 18 show what happens when α is changed when the gravure diameter is 100 mm and the mesh 100 and R is 2.5. A print pattern appeared when α was 50, but no print pattern appeared when α was 60 degrees.
Therefore, when R is around 2.5, it is assumed that α has a boundary at 60 degrees.
[0053]
From the above, the following can be said roughly.
(1) When R ≦ 0.3, the predetermined angle α ≦ 45 degrees,
(2) If 0.3 <R ≦ 2, 45 <α ≦ 60 degrees,
(3) If 2 <R, 60 ≦ α,
It turns out that it is good.
[0054]
As for the gravure roll, from Table 1, it is considered that the outer diameter is preferably 15 mm to 250 mm and the mesh is # 100 to 1500 / inch.
[0055]
FIG. 9 is an explanatory view showing a number of thin engraving gravure rolls engraved in parallel at various engraving angles α with respect to the roll circumferential direction, (a) α1 = 80 degrees, (b) α2 = 60 °, (c) is a gravure roll having parallel grooves of α3 = 45 °, (d) is α4 = 30 °, and (e) is α5 = 20 °.
In this gravure coating apparatus, a large number of such gravure rolls having various αs are prepared, and the speed ratio (Vb / Vg) is determined from the film base running speed (Vb) and the gravure roll surface rotation speed (Vg). ) R is obtained, and every time the ratio R is different, a gravure roll satisfying the above relationship is selected and used.
[0056]
【The invention's effect】
As described above, a number of thin engraving patterns carved in parallel at a predetermined angle α with respect to the circumferential direction of the roll on the surface of the gravure roll 1 are the film base traveling speed (Vb) and the rotation of the gravure roll surface. When the ratio (Vb / Vg) to the speed (Vg) is R,
(1) When R ≦ 0.3, the predetermined angle α ≦ 45 degrees,
(2) If 0.3 <R ≦ 2, 45 <α ≦ 60 degrees,
(3) If 2 <R, 60 ≦ α,
The coating amount is 10 cc / m ² Even when applied below, it is possible to prevent the gravure roll from appearing on the coated surface.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a gravure coating method and apparatus.
FIG. 2 is a schematic explanatory view showing a main part of a conventional gravure coating method.
FIG. 3 is an explanatory view showing a problem of a conventional gravure coating method.
4 is an explanatory view schematically showing the problem shown in FIG. 3. FIG.
FIG. 5 is an explanatory view of a conventional blade coater according to a known example.
FIG. 6 is a diagram for explaining a conventional measure for uniformizing the contact of a blade.
FIG. 7 is an explanatory view showing a shaft support structure of a gravure roll.
FIG. 8 is an explanatory view showing a large number of thin sculptured gravure rolls engraved in parallel at a predetermined angle with respect to the roll circumferential direction.
FIG. 9 is an explanatory view showing a large number of thin gravure patterns engraved in parallel at various angles with respect to the roll circumferential direction.
10A and 10B are explanatory diagrams of a gravure coating method according to an embodiment of the present invention, in which FIG. 10A is a perspective view exaggerating bending, and FIG. 10B is a view taken along the arrow Ib in FIG.
FIG. 11 is an explanatory view showing how to obtain the deflection of the gravure roll when the gravure coating method is carried out.
FIG. 12 is an explanatory diagram of conditions used for calculating the deflection of the gravure roll.
FIG. 13 is a side view of a blade holder used in the gravure coating apparatus.
FIG. 14 is an enlarged view of a doctor blade tip.
FIG. 15 is a perspective view showing a state in which a doctor blade held by a blade holder is pressed against a gravure roll.
[Explanation of symbols]
1 Gravure roll
2 Coating liquid
3 Doctor blade
3a Contact end
4 Film base
5 Coating solution reservoir (coating solution supply unit)
11 Diagonal sculpture carved on the gravure roll surface
20, 40, 50 Blade holder
21, 22 Presser plate
21a, 22a Curved surface
23, 24 Metal block
23a, 24a Curved surface
33 Vertical movement mechanism (holder bending imparting means)
α of the sculpture oblique line carved on the surface of the gravure roll Circumference Angle to direction

Claims (3)

A gravure roll having a mesh parallel to the roll circumferential direction at a predetermined angle α is rotated, and a 0.1 to 20 cP coating solution containing particles having a particle size of 10 μm or less is supplied to the gravure roll surface. The doctor film pressed against the surface of the gravure roll scrapes off the excess coating liquid on the surface of the gravure roll, and the plastic film travels in the direction opposite to the rotation direction of the gravure roll in a state where the plastic film is pressed against the gravure roll. In the gravure coating method of coating the coating liquid in the engraving pattern on the plastic film at a coating amount of 10 cc / m ² or less,
When the traveling speed of the plastic film is Vb and the rotational speed of the gravure roll surface is Vg, the relationship between the ratio R = Vb / Vg and the predetermined angle α is any of the following (1) to (3) A gravure coating method characterized by satisfying one .
(1) When R ≦ 0.3, the predetermined angle α ≦ 45 degrees (2) When 0.3 <R ≦ 2, 45 <α ≦ 60 degrees (3) When 2 <R, 60 ≦ α.   2. The gravure coating method according to claim 1, wherein the outer diameter of the gravure roll is 15 mm to 250 mm and the mesh is # 100 to 500 / inch. A gravure roll for applying a coating liquid to a film base, and having a large number of fine engraving patterns on the surface engraved in parallel at a predetermined angle α with respect to the roll circumferential direction;
A coating liquid supply unit for supplying the coating liquid to the surface of the gravure roll;
A doctor blade that scrapes off the excess coating liquid on the surface of the gravure roll by being pressed against the surface of the gravure roll from when the coating liquid is supplied until it contacts the film base;
Gravure coating comprising: a film base supply means for running the film base in a direction opposite to the rotation direction of the gravure roll, and applying the coating liquid in the engraving pattern to the film base at a coating amount of 10 cc / m ² or less. In the device
The gravure roll is composed of at least three types of gravure rolls, the gravure roll with the predetermined angle α ≦ 45 degrees, the gravure roll with 45 <α ≦ 60 degrees, and the gravure roll with 60 ≦ α. Gravure coating device characterized by this.

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