JP4431368B2 - Coating apparatus and coating method - Google Patents

Description

  The present invention relates to a coating apparatus that applies a coating liquid to a continuously running belt-like web such as paper, cloth, or plastic film.

In a coating device that applies a coating liquid to a belt web that runs continuously, a part of the air layer that is entrained in the vicinity of the web that travels enters the device that feeds and attaches the coating liquid, and the application surface has streaks and pinholes. There is a so-called air entrainment phenomenon in which coating defects such as the above occur. In particular, when the coating speed is increased, the air entrainment phenomenon becomes remarkable, and the coating speed cannot be increased (so-called critical coating speed). Conventionally, as a method for suppressing the air entrainment phenomenon, a method has been proposed in which a decompression chamber is installed on the upstream side of an apparatus for supplying and adhering a coating liquid (see Patent Document 1).
Japanese Patent Laid-Open No. 2003-53228

  The present invention applies a coating solution to a continuously running belt-like web such as paper, cloth, plastic film, and the like, in a coating process in which a liquid coating layer is formed on a continuously running web, with simple and low cost. An object of the present invention is to provide a coating apparatus that can obtain a high-quality coated surface even when the coating speed is increased.

(1) A coating apparatus according to claim 1 of the present invention is a coating apparatus that applies a coating liquid to a web that continuously runs while being supported by a backing roll, and supplies the coating liquid to the web. And a flexible sheet provided on the partition on the upstream side of the coating liquid supply unit, and an interval provided between one end of the flexible sheet and the web surface supported by the backing roll is It is characterized by being smaller than the distance provided between the one end and the web surface supported by the backing roll.

(2) For example, the coating liquid supply unit is an open type liquid storage pan, and the flexible sheet is placed on the bottom plate of the liquid storage pan.

(3) The coating apparatus according to claim 3 of the present invention is a coating apparatus that applies a coating liquid to a continuously running web, and a coating liquid supply section that supplies the coating liquid to the web, and a coating liquid supply section The pressure reducing chamber provided adjacent to the upstream side of the pressure reducing chamber and the flexible sheet provided on the partition wall on the upstream side of the pressure reducing chamber, the space provided between one end of the flexible sheet and the web surface is It is characterized by being smaller than the distance provided between one end of the web and the web surface.

(4) A coating apparatus according to claim 4 of the present invention is a coating apparatus that applies a coating liquid to a web that continuously runs while being supported by a backing roll, and supplies the coating liquid to the web. Part, a decompression chamber provided adjacent to the upstream side of the coating liquid supply part, and a flexible sheet provided on at least one of the partition wall upstream of the coating liquid supply part or the partition wall upstream of the decompression chamber The distance provided between the one end of the flexible sheet and the web surface is smaller than the distance provided between the one end of the partition wall and the web surface.

(5) In each of the above-described coating apparatuses, the interval provided between one end of the flexible sheet and the web surface is preferably not more than half of the interval provided between one end of the partition and the web surface.

  As described above, according to the present invention, in the coating process for forming a liquid coating layer on a continuously running web, the air entrainment phenomenon is suppressed easily and at low cost, and a high-quality coating surface can be obtained even when the coating speed is increased. It is possible to provide a coating apparatus capable of obtaining the above.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a side view schematically showing a part of the open type coating apparatus according to the first embodiment of the present invention.

  The coating apparatus 10 of this embodiment has a cylindrical backing roll 11, and a belt-like web W is wound around the outer peripheral surface thereof. The backing roll 11 is rotated around a central axis L0 arranged horizontally, and feeds the web W in the longitudinal direction. That is, in FIG. 1, the backing roll 11 is rotated clockwise, and the web W is unwound from an unillustrated unwinding portion and fed into the backing roll 11 from the A direction (obliquely lower side). Thereafter, the web is fed out from the backing roll 11 in the B direction (obliquely upper side), and is wound on the winding unit through a drying unit (not shown), for example.

  On the shoulder of the backing roll 11 around which the web W is wound, there is a liquid reservoir bed 12 for storing the coating liquid L, and a doctor for measuring the coating amount of the coating liquid L on the web W (the thickness of the coating film F). A knife 15 is arranged. The liquid reservoir bed 12 is surrounded by a liquid reservoir pan 13 composed of a three-dimensionally shaped thin plate, a backing roll 11, and a doctor knife 15, and the upper part thereof is open.

  The liquid storage pan 13 includes, for example, a bottom plate portion (partition wall) 13a and a back plate 13b. The liquid storage pan has two sidewalls (not shown) parallel to the paper surface of FIG. No plate is provided on the backing roll 11 side, and the coating liquid L is supported by the web itself supported by the backing roll 11. A gap d0 is provided between the surface of the web W and one end of the bottom plate portion 13a. The web W enters the liquid storage bed 12 as the backing roll 11 rotates. The outer circumferential surface of the web W that has entered the liquid reservoir bed 12 contacts the coating liquid L in the liquid reservoir bed 12, and the coating liquid L is applied to the surface of the web W.

  The doctor knife 15 is fixed at a predetermined distance from the backing roll 11 on the downstream side of the liquid storage pan as is well known in the art, and its axis is kept parallel to the central axis L0 of the backing roll 11. The web W passes between the doctor knife 15 and the backing roll 11 and is fed out in the B direction. At this time, the thickness of the coating film F made of the coating liquid L attached to the web W by the doctor knife 15 becomes a predetermined thickness. Weighed. In addition, the coating liquid amount in the liquid reservoir bed 12 is kept constant by a conventionally known method (for example, supplying a coating liquid corresponding to the coating amount from the open portion).

  A distance d0 between one end of the bottom plate portion 13a and the surface of the web W supported by the backing roll 11 is about 2 to 10 times the thickness of the web W. This is because the surface of the web W should have wrinkles and deposits (powder falling, fluffing, etc.), especially when there is a seam in the web W, the seam of the web W is between the bottom plate portion 13a and the backing roll 11. This is to prevent it from being pinched. For this reason, the interval d0 cannot be set very small. Therefore, in the conventional open type coating apparatus, since the interval d0 is wide, the entrained air layer in the vicinity of the web W is mixed into the liquid reservoir bed 12 to form bubbles, and coating defects such as coating stripes and pinholes are formed on the coating surface. The problem that occurs. Further, if the distance d0 is wide, the coating liquid may leak out from this gap when the viscosity of the coating liquid L is low.

  Also, in the case of a conventional coating apparatus that suppresses the generation of bubbles due to air entrainment using a decompression chamber, for the same reason as described above, the distance between one end of the upstream wall of the decompression chamber and the web is reduced. Since it cannot be set to a minute value, in order to suppress the generation of bubbles due to the air entrainment phenomenon, it is necessary to increase the amount of air to be sucked in order to maintain a predetermined degree of decompression, and there is a problem that the decompression power becomes large. appear.

  Due to the problems of the conventional apparatus as described above, in the present embodiment, a flexible sheet such as a polyethylene terephthalate film (for example, a thickness of about 50 μm) is formed on the bottom plate portion 13a of the liquid pan 13 on the upper surface (FIG. 1), for example. 16 is placed. A gap d1 is provided between one end of the flexible sheet 16 and the surface of the web W supported by the backing roll 11, and the gap d1 is supported by one end of the bottom plate portion 13a and the backing roll 11. It is set to be smaller than the distance d0 with the surface of the web W that is on. More preferably, the interval d1 is set to half or less of the interval d0.

  Since the flexible sheet 16 has flexibility, the gap d <b> 1 can be set to be minute even if there are wrinkles, deposits, or seams on the web. That is, even when a seam or the like having a thickness larger than the distance d1 passes through the web entrance E1, the flexible sheet 16 can bend downstream, so that such a part can pass without any problem. can do.

  As described above, according to the open-type coating apparatus according to the first embodiment of the present invention, the distance between the web surface and the web surface can be set very small, so that the entrained air layer in the vicinity of the web enters the liquid storage pan. And the generation of bubbles due to the air entrainment phenomenon can be sufficiently suppressed. Moreover, since the space | interval with a web surface can be set very minutely, even when the viscosity of a coating liquid is low, it can prevent that a coating liquid leaks from the clearance gap between web surfaces.

  Therefore, a coating liquid having a lower viscosity can be used even in the coating process in which the web having a seam is continuously run, and the coating liquid viscosity range that can be applied can be expanded. Moreover, it becomes possible to improve the critical coating speed at which air entrainment does not occur due to a decrease in the coating liquid viscosity.

  In the first embodiment, the flexible sheet 16 is placed on the upper surface in FIG. 1 of the liquid storage pan bottom plate portion 13a. However, the flexible sheet 16 is further placed continuously on the inner surface of the back plate 13b. Can be easily attached, and the liquid storage pan can be prevented from being soiled, thereby improving workability. Moreover, you may mount the flexible sheet | seat 16 in the lower surface in FIG.

  Next, a coating apparatus using a decompression chamber according to the second embodiment of the present invention will be described with reference to FIG. FIG. 2 is a side view schematically showing a part of a coating apparatus using the decompression chamber of the second embodiment. Note that the same reference numerals are used for configurations common to the first embodiment.

  The coating device 20 of the second embodiment is of a type that travels on the web W using the backing roll 11, as in the open type coating device 10 of the first embodiment, but the liquid reservoir bed of the first embodiment. An application head 21 is used in place of 12 and the doctor knife 15. Examples of the coating head 21 include a slot die coating head, a slide die coating head, and a curtain die coating head. Note that when the coating apparatus is operated, a predetermined amount of coating liquid L is always supplied to the coating head 21 from a coating liquid supply system (not shown).

  Further, a decompression chamber 22 is provided adjacent to the upstream side of the coating head 21, that is, the lower side, and the air in the decompression chamber 22 is sucked and discharged from the air suction port 23 to the outside through a duct (not shown). Is done. A gap d ′ 0 is provided between one end of the upstream wall 22 a that defines the housing of the decompression chamber 22 and the surface of the web W supported by the backing roll 11. Further, the flexible sheet 16 is provided on the lower surface of the wall 22a, for example, and a gap d ′ is provided between one end of the flexible sheet 16 and the surface of the web W supported by the backing roll 11. 1 gap is provided. The web W traveling by the rotation of the backing roll 11 enters the decompression chamber 22 through the web entrance E <b> 2, and the coating liquid L is applied to the surface of the coating head 21. At this time, since the air layer entrained in the vicinity of the surface of the web W is peeled off from the web W by the flexible sheet 16 and the decompression chamber 22, the problem associated with air entrainment is greatly improved. The intervals d′ 0 and d′ 1 in the second embodiment are set under the same conditions as the intervals d0 and d1 in the first embodiment, for example.

  As described above, according to the coating apparatus according to the second embodiment of the present invention, the depressurization power for maintaining the same depressurization degree is reduced, or the absolute value of the depressurization degree obtained with the same depressurization power is improved. Moreover, the air entrainment suppression effect can be enhanced and the critical coating speed can be improved.

  Next, a coating apparatus using a decompression chamber according to a third embodiment of the present invention will be described with reference to FIG. FIG. 3 is a side view schematically showing a part of a coating apparatus using the decompression chamber of the third embodiment. Note that the same reference numerals are used for configurations common to the first and second embodiments.

  The coating device 30 of the third embodiment is a coating device that uses, for example, a tension web method, and applies the coating liquid L to the surface of the belt-like web W that continuously travels in a plane using the coating head 31. . In the present embodiment, the web W is depicted as traveling in the left-right direction in the figure, but it may be traveling in the up-down direction.

  The web W passes through a guide roller (not shown) arranged on the left side in the drawing, and then is sent in the right direction (arrow C) in the drawing via a guide roller (not shown) arranged on the right side. . The coating head 31 is disposed at a position where the web W is stretched between the left and right guide rollers. As in the second embodiment, the application head 31 includes a doctor knife application head, a slot die application head, a slide die application head, a curtain die application head, and the like. Is always supplied with a predetermined amount of coating liquid L from a coating liquid supply system (not shown).

  As in the second embodiment, a decompression chamber 32 is disposed adjacent to the upstream side (left side in the drawing) of the coating head 31. That is, the air in the decompression chamber 32 is sucked and discharged from the air suction port 23 to the outside by a suction device through a duct (not shown). A distance d'0 is set between one end of the upstream wall 32a defining the housing of the decompression chamber 32 and the surface of the web W (coating head surface). Further, the flexible sheet 16 is provided on the upstream surface (the left surface in the figure) of the wall 32a, and the distance d'1 is set between one end of the flexible sheet 16 and the surface of the web W. Is done.

  Similar to the second embodiment, the air layer entrained in the vicinity of the surface of the web W is peeled off from the web W by the flexible sheet 16 and the decompression chamber 32. Further, the intervals d′ 0 and d′ 1 in the third embodiment are set under the same conditions as the intervals d0 and d1 in the first embodiment, for example.

  As described above, also in the coating apparatus according to the third embodiment of the present invention, the same effect as in the second embodiment can be obtained.

  Note that a decompression chamber may be provided on the upstream side (lower side) of the liquid storage pan of the first embodiment. In the second or third embodiment, a flexible sheet may be provided on the wall surface that defines the coating head and the decompression chamber, and the entrance of the web to the coating head may be set minutely.

  Hereinafter, the effects of the first to third embodiments of the present invention will be described by giving examples together with comparative examples.

  In the following comparative examples and examples, a doctor knife type coating method was used. A solvent-type adhesive solution was used that was close to Newtonian fluid, and a shear thinning fluid was used for the emulsion-type adhesive solution. Further, a 50 μm polyethylene terephthalate film was used for the flexible sheet, and the thickness of the web was 50 μm. Further, the distance d1 between one end of the flexible sheet and the web surface was 30 μm. In addition, the space | interval d0 between the one end of the bottom plate part of a liquid storage pan and the web surface is described in each Example. Moreover, in the web which has a seam, the adhesive tape of polyethylene terephthalate 50 micrometers was stuck on the single side | surface of the web.

  Examples 1 to 6 are experimental results in the coating apparatus of the first embodiment, and correspond to the results of Comparative Examples 1 to 6 in a conventional coating apparatus that does not use a vacuum chamber. Example 7 is an experimental result with respect to the coating apparatus of the second embodiment, and corresponds to the experimental result of Comparative Example 7 in a conventional coating apparatus using a vacuum chamber. In Example 8, in the coating apparatus of the second embodiment, in addition to the flexible sheet provided on the upstream surface of the decompression chamber, the flexible sheet was provided on the downstream wall surface of the decompression chamber. It is an experimental result with respect to a coating device.

(Comparative Example 1 and Example 1)
Coating liquid used: Solvent-based adhesive solution (shear viscosity 1500 mPa · s)
Web: seamless interval d0: 100 μm
Under the above conditions, the critical coating speed in Comparative Example 1 (maximum coating speed without causing air entrainment) was 70 m / min, whereas the critical coating speed in Example 1 was Was 90 m / min.

(Comparative Example 2 and Example 2)
Coating liquid used: Solvent-based adhesive solution (shear viscosity 1500 mPa · s)
Web: There is a joint Interval d0: 200 μm
Under the above conditions, the critical coating speed in Comparative Example 2 was 60 m / min, whereas the critical coating speed in Example 2 was 90 m / min.

(Comparative Example 3 and Example 3)
Coating liquid used: Solvent-based adhesive solution (shear viscosity 500 mPa · s)
Web: There is a joint Interval d0: 200 μm
Under the above conditions, in Comparative Example 3, liquid leakage occurred and coating was impossible. On the other hand, in Example 3, liquid leakage did not occur and the critical coating speed was 100 m / min.

(Comparative Example 4 and Example 4)
Used coating solution: Emulsion-type adhesive solution
10000 mPa · s when the shear viscosity is a shear strain rate of 10 s ⁻¹
500 mPa · s at a shear strain rate of 1000 s ^-1
Web: seamless interval d0: 100 μm
Under the above conditions, the critical coating speed in Comparative Example 4 was 50 m / min, whereas the critical coating speed in Example 4 was 70 m / min.

(Comparative Example 5 and Example 5)
Used coating solution: Emulsion-type adhesive solution
10000 mPa · s when the shear viscosity is a shear strain rate of 10 s ⁻¹
500 mPa · s at a shear strain rate of 1000 s ^-1
Web: There is a joint Interval d0: 200 μm
Under the above conditions, the critical coating speed in Comparative Example 5 was 40 m / min, whereas the critical coating speed in Example 5 was 70 m / min.

(Comparative Example 6 and Example 6)
Used coating solution: Emulsion-type adhesive solution
The shear viscosity is 5000 mPa · s when the shear strain rate is 10 s ^−1.
250 mPa · s at a shear strain rate of 1000 s ^-1
Web: There is a joint Interval d0: 200 μm
Under the above conditions, in Comparative Example 6, when the coating speed exceeded 30 m / min, liquid leakage occurred and coating was impossible. On the other hand, in Example 6, the critical coating speed was 70 m / min.

(Comparative Example 7 and Example 7)
Used coating solution: Emulsion-type adhesive solution
10000 mPa · s when the shear viscosity is a shear strain rate of 10 s ⁻¹
500 mPa · s at a shear strain rate of 1000 s ^-1
Web: seamless interval d′ 0: 100 μm
Interval d′ 1: 30 μm
Decompression degree: -500 Pa
Under the above conditions, the critical coating speed in Comparative Example 7 was 80 m / min, whereas the critical coating speed in Example 7 was 95 m / min.

(Example 8)
Used coating solution: Emulsion-type adhesive solution
10000 mPa · s when the shear viscosity is a shear strain rate of 10 s ⁻¹
500 mPa · s at a shear strain rate of 1000 s ^-1
Web: seamless distance d0, d′ 0: 100 μm
Interval d1, d′ 1: 30 μm
Decompression degree: -500 Pa
The experimental conditions of Example 8 in the above are the same as those of Comparative Example 7 except for the conditions relating to the flexible sheet. Here, d0 is the distance between the surface of the web W and one end of the downstream wall 22b in the decompression chamber 22, and d1 is the surface of the web W and one end of the flexible sheet provided on the wall 22b. Corresponds to the distance between. As described above, the critical coating speeds in Comparative Example 7 and Example 7 were 80 m / min and 95 m / min, whereas in Example 8, the critical coating speed increased to 110 m / min.

  As described above, in any of the Examples, the critical coating speed is remarkably improved and problems such as liquid leakage are solved as compared with the comparative example using the conventional coating apparatus.

It is a side view which shows typically a part of open type coating device which is 1st Embodiment of this invention. It is a side view which shows typically a part of coating device using the pressure reduction chamber which is 2nd Embodiment of this invention. It is a side view which shows typically a part of coating device using the pressure reduction chamber which is 3rd Embodiment of this invention.

Explanation of symbols

10, 20, 30 Coating device 11 Backing roll 13 Liquid storage pan (coating liquid supply unit)
13a Bottom plate (partition)
16 Flexible sheet 21, 31 Application head (coating liquid supply part)
22, 32 Depressurization chamber W Web F Coating film

Claims (11)

A coating device that applies a coating liquid to a web that runs continuously while being supported by a backing roll,
A coating liquid supply unit for supplying the coating liquid to the web;
A flexible sheet provided on the partition on the upstream side of the coating liquid supply unit,
An interval provided between one end of the flexible sheet and the web surface is less than half of an interval provided between the one end of the partition and the web surface, and the one end of the partition and the web surface The coating apparatus is characterized in that the distance between the two is 2 to 10 times the thickness of the web .   The coating apparatus according to claim 1, wherein the coating liquid supply unit is an open-type liquid storage pan, and the flexible sheet is placed on a bottom plate portion of the liquid storage pan. The coating apparatus according to claim 2, wherein the flexible sheet is continuously placed from a bottom plate portion of the liquid storage pan to an inner surface of a back plate of the liquid storage pan. An application device for applying a coating liquid to a continuously running web,
A coating liquid supply unit for supplying the coating liquid to the web;
A decompression chamber provided adjacent to the upstream side of the coating liquid supply unit;
A flexible sheet provided on the upstream partition wall of the decompression chamber,
An interval provided between one end of the flexible sheet and the web surface is less than half of an interval provided between the one end of the partition and the web surface, and the one end of the partition and the web surface The coating apparatus is characterized in that the distance between the two is 2 to 10 times the thickness of the web . A coating device that applies a coating liquid to a web that runs continuously while being supported by a backing roll,
A coating liquid supply unit for supplying the coating liquid to the web;
A decompression chamber provided adjacent to the upstream side of the coating liquid supply unit;
A flexible sheet provided on at least one of the upstream partition wall of the coating liquid supply unit or the upstream partition wall of the decompression chamber;
An interval provided between one end of the flexible sheet and the web surface is less than half of an interval provided between the one end of the partition and the web surface, and the one end of the partition and the web surface The coating apparatus is characterized in that the distance between the two is 2 to 10 times the thickness of the web . The interval provided between one end of the flexible sheet and the web surface is 30% or less of the interval provided between the one end of the partition and the web surface. The coating apparatus according to any one of 5. The space provided between one end of the flexible sheet and the web surface is 15% or less of the space provided between the one end of the partition and the web surface. 4. The coating apparatus according to any one of 3. The coating apparatus according to claim 1, wherein an interval provided between one end of the flexible sheet and the web surface is 30 μm. An application method for applying a coating liquid to a web that continuously runs while being supported by a backing roll,
Supplying the coating liquid from the coating liquid supply unit to the web;
Providing a flexible sheet on the upstream partition wall of the coating liquid supply unit;
The interval provided between one end of the flexible sheet and the web surface is set to be equal to or less than half of the interval provided between the one end of the partition and the web surface, and the one end of the partition and the web Set the spacing between the surfaces to 2-10 times the thickness of the web
The coating method characterized by the above-mentioned. An application method for applying a coating liquid to a continuously running web,
Supplying the coating liquid from the coating liquid supply unit to the web;
A decompression chamber is provided adjacent to the upstream side of the coating liquid supply unit,
Providing a flexible sheet on the upstream partition wall of the decompression chamber;
The interval provided between one end of the flexible sheet and the web surface is set to be equal to or less than half of the interval provided between the one end of the partition and the web surface, and the one end of the partition and the web Set the spacing between the surfaces to 2-10 times the thickness of the web
The coating method characterized by the above-mentioned. An application method for applying a coating liquid to a web that continuously runs while being supported by a backing roll,
Supplying the coating liquid from the coating liquid supply unit to the web;
A decompression chamber is provided adjacent to the upstream side of the coating liquid supply unit,
A flexible sheet is provided on at least one of the upstream partition wall of the coating liquid supply unit or the upstream partition wall of the decompression chamber,
The interval provided between one end of the flexible sheet and the web surface is set to be equal to or less than half of the interval provided between the one end of the partition and the web surface, and the one end of the partition and the web Set the spacing between the surfaces to 2-10 times the thickness of the web
The coating method characterized by the above-mentioned.

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