JP6528476B2 - Coating apparatus and coating method - Google Patents

Description

  The present invention relates to a coating apparatus and a coating method.

  As a coating apparatus such as a coating apparatus, one including a liquid discharge means (droplet discharge means) such as a liquid discharge head (droplet discharge head) is known.

  For example, it is known that the coating liquid is discharged toward the center of the cylinder, which is the axis of rotation, to the rotating cylindrical object to be coated, and the droplets of the coating liquid are applied to the surface of the object to overlap. (Patent Document 1).

Japanese Patent Application Publication No. 11-19554

  However, in the configuration disclosed in Patent Document 1, when the number of rotations of the object to be coated is increased to realize application at higher speed, an air flow in the rotation direction is generated on the surface of the rotating body, and the air flow is generated by the air flow. Droplets that do not land on the coated material are generated, and coating unevenness occurs on the site. Therefore, there is a problem that the application speed can not be increased to increase the productivity.

  This invention is made in view of said subject, and it aims at improving productivity of application | coating operation, suppressing application | coating nonuniformity.

To solve the above problem, a coating apparatus according to the present onset Ming,
Liquid discharge means for discharging droplets of the application liquid to the application member;
The liquid discharge means is a member for applying the liquid droplet from the point where the droplet discharge direction intersects the straight line connecting the nozzle that discharges the droplet and the rotation center of the member to be coated and the application surface of the member to be coated. It is arranged in a state where it is directed to the upstream side in the rotational direction,
The liquid discharge means is disposed at a position where the liquid droplet lands on a normal to the rotation center of the application member.

  According to the present invention, the productivity of the coating operation can be improved while suppressing the coating unevenness.

It is a typical explanatory view seen from the rotation center direction of the application member in which it uses for explanation of one embodiment of the present invention. FIG. 7 is an explanatory view provided to explain an operation of the embodiment. FIG. FIG. FIG. It is an explanatory view provided for explanation of a comparative example with the embodiment. FIG. FIG. 21 is an explanatory view serving to explain another comparative example with the embodiment. FIG. It is a schematic explanatory drawing of the coating device which concerns on this invention. It is an expansion explanatory view of the movable part of the coating device. It is a typical explanatory view given to explanation of arrangement of a drop measurement means. FIG. 2 is a schematic explanatory view of an example of a liquid discharge head. It is plane explanatory drawing of the nozzle plate of the head. It is a plane explanatory view of a channel board similarly. FIG. 6 is a flowchart for explaining the rotational speed setting process of the member to be coated; FIG. 6 is a flowchart for describing control (process) related to a coating operation. FIG. 18 is a flow chart provided for explanation following FIG. 17; FIG. 18 is an explanatory view for explaining a coating state when the coating operation of FIG. 17 is performed. It is explanatory drawing which similarly demonstrates an application | coating state. It is explanatory drawing which similarly demonstrates an application | coating state. It is explanatory drawing which similarly demonstrates an application | coating state. It is explanatory drawing of the head specification used for description of specific Example 1 and Comparative Examples 1 and 2. FIG. It is an explanatory view which is provided for explanation of arrangement of a head of Example 1 and comparative examples 1 and 2 and a member to be coated, and a rotation direction. FIG. 7 is an explanatory view provided for explaining the operation of the first embodiment. FIG. 14 is an explanatory view for describing an operation of comparative example 2;

  Hereinafter, embodiments of the present invention will be described with reference to the attached drawings. One embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic explanatory view seen from the rotation center direction of the application member to be used for explaining the embodiment.

  The coating apparatus of the present embodiment is provided with a liquid discharge head 1 which is a liquid discharge means for discharging droplets 61 of a coating liquid on the circumferential surface of a member to be coated 51. The application member 51 is a cylindrical (including cylindrical) member that is rotated in the arrow direction (direction B).

Here, in the liquid discharge head 1, a straight line a connecting the nozzle 40 for discharging the droplet 61 and the rotation center O of the application member 51 is the circumferential surface (application surface) of the application member 51. Are arranged in a direction toward the upstream side in the rotational direction of the application member 51 from the point of intersection thereof.

  In addition, the liquid discharge head 1 is disposed in a state in which the droplet discharge direction is a direction directed downward in the gravity direction (vertical direction).

  Further, in the liquid discharge head 1, when the rotation direction of the application member 51 is clockwise, the nozzle 40 is disposed in the second quadrant. At this time, in the liquid discharge head 1, the nozzle 40 is at a position lower than the highest position c or the position c in the direction of gravity.

  In addition, the liquid discharge head 1 is disposed at a position where the droplet 61 lands from above the normal line d to the rotation center O of the application member 51. Here, the droplet discharge speed of the droplet 61, the rotation speed of the application member 51, and the position of the liquid discharge head 1 are set so that the droplet 61 lands on the normal line d.

  Next, the operation of the embodiment configured as described above will be described.

  First, the behavior of the droplet 61 discharged from the liquid discharge head 1 until the droplet 61 lands on the circumferential surface (application surface) of the application member 51 will be described.

  The droplets 61 ejected from the nozzles 40 of the liquid ejection head 1 fly in a direction perpendicular to the surface on which the nozzles 40 are formed (vertically downward in FIG. 1).

  At this time, an air flow in the rotational direction is generated in the vicinity of the coated surface of the application member 51 due to the rotation of the application member 51.

  As a result, as the droplet 61 approaches the coating surface of the application member 51, the air flow generated by the rotation of the application member 51 gradually flows in the air flow direction indicated by a thick arrow in FIG.

  At this time, assuming that the discharge direction from the nozzle 40 is directed to the rotation center O of the application member 51, the droplets flowed in the air flow are moved away from the application member 51. When the speed of the air flow is equal to or higher than a certain speed, the air does not land on the application member 51.

  Actual droplets have variations in droplet velocity and droplet amount, so as the air flow becomes faster, the amount of landing drops gradually increases, which causes application unevenness.

On the other hand, in the coating apparatus according to this embodiment shown in FIG. 1, the droplet discharge direction A is a straight line connecting the nozzle 40 for discharging the droplets 61 and the rotation center O of the application member 51 By setting the direction toward the upstream side in the rotational direction of the application member 51 with respect to the point intersecting with the circumferential surface (application surface) of 51, the droplet 61 is rather applied By approaching the member 51, the landing rate of the droplet 61 on the application member 51 is dramatically increased. This enables high-speed application without coating unevenness.

  In addition, since the liquid discharge head 1 is disposed in a state in which the droplet discharge direction is directed downward in the gravity direction (vertical direction), the action direction of the air flow is against the gravity, so that the air flow is faster. Even if (the rotational speed of the application member 51), the landing rate can be maintained.

  Further, the liquid discharge head 1 sets the droplet 61 above the discharge position (nozzle 40) by setting the nozzle 40 at a position lower than the highest position c or position c of the application member 51 in the gravity direction. As long as the air flow is not strong enough to fly, the ink can be landed on the application member 51 with certainty.

  In addition, when the droplet 61 is discharged from the liquid discharge head 1, as shown in FIG. 1, a minute mist 62 may be generated, but the light weight mist 62 is a rotation of the application member 51. It is made to flow by the air flow which arises by this, and is blown off, without landing on the application surface of application member 51. As a result, the droplets 61 can be landed reliably, and the mist 62 can not be landed, thereby enabling uniform coating.

  Furthermore, here, the liquid discharge head 1 is disposed such that the droplets 61 made to flow by the air flow land on the coated surface of the application member 51 in the normal direction.

  Thereby, as shown in FIG. 2, the droplet 61 starts contacting the droplet 61 almost perpendicularly to the coated surface, and at the same time the coated member 51 is rotated, as shown in FIG. It is thinly stretched in the rotational direction of the application member 51. Then, as shown in FIG. 4 and FIG. 5, when the landing of the droplets 61 is completed, it is possible to make the coated droplet 67 thinly drawn to a substantially uniform thickness on the coating surface.

  On the other hand, the landing state in the case where the droplet 61 does not land on the application surface in the normal direction of the application member 51 will be described with reference to FIGS. 6 to 9.

  Even when the liquid discharge head 1 is disposed as in the embodiment, for example, when the rotational speed of the application member 51 is high (or the drop speed is low), the flight path of the droplet 61 is shown in FIG. It will be. That is, the droplet 61 intrudes at an acute angle from the upstream side to the downstream side in the rotational direction with respect to the application surface and lands there.

  At this time, since the velocity difference between the application surface and the droplet 61 is small in the moving direction of the application surface, as shown in FIG. 7, the degree of stretching of the landed droplet 61 becomes small and the film thickness becomes thick. It becomes difficult to form a uniform thin film.

  On the other hand, for example, when the rotational speed of the application member 51 is low (or the drop speed is high), the flight path of the droplet 61 is as shown in FIG. That is, the droplet 61 intrudes at an acute angle from the downstream side to the upstream side in the rotational direction with respect to the application surface and lands there.

  At this time, the flight direction of the droplets 61 and the rotation direction of the application member 51 are substantially opposite to each other, and the relative velocity between them becomes extremely large. The droplet 61 landed on the application member 51 in such a state is distorted in the landing shape as shown in FIG. 9 and the uniformity of the film thickness is slightly reduced.

  In addition, when the rotational speed of the application member 51 is reduced, the air flow around the application member 51 also decreases, and therefore the mist 62 generated when discharging the droplet 61 may land on the application surface. . In this case, the uniformity of the film thickness will be further reduced.

  As described above, when the droplets 61 land on the coated surface of the application member 51 in the normal direction, uniform thin film application to the application member 51 can be performed.

  Next, a coating apparatus according to the present invention will be described with reference to FIGS. 10 to 12. FIG. 10 is a schematic explanatory view of the coating apparatus, FIG. 11 is an enlarged explanatory view of a movable part of the coating apparatus, and FIG. 12 is a schematic explanatory view for explaining the arrangement of the drop measuring means.

  The coating liquid is supplied to the liquid discharge head 1 from a liquid tank (not shown) that stores the coating liquid. A trigger sensor 58 is disposed corresponding to the liquid discharge head 1.

  The work stage 54 is disposed to be reciprocally movable in the arrow direction with respect to the liquid discharge head 1.

  The work stage 54 includes, on the stage 57, rotatable holders 56, 56 for supporting the application member 51 at both axial ends, and a drive motor 57 for rotating the application member 51 via the holder 56. ing.

  Further, on the bottom side of the stage 57, sensor dogs 52 and 53 detected by the trigger sensor 58 are provided. The trigger sensor 58 detects the edges 52R, 52L, 53R, 53L of the sensor dogs 52, 53 to control the application start and the application end.

  Further, as shown in FIG. 12, the camera includes a camera 70 for measuring the flying speed and direction of the droplets 61 discharged from the liquid discharge head 1 and a droplet measuring means constituted by illumination not shown.

  Next, an example of the liquid discharge head will be described with reference to FIG. 13 to FIG. FIG. 13 is a schematic explanatory view of the liquid discharge head, FIG. 14 is a plan explanatory view of a nozzle plate of the same head, and FIG. 15 is a plan explanatory view of a flow path plate.

  The liquid discharge head 1 includes a drive unit 3 and a liquid chamber unit 2 joined to the drive unit 3.

  The drive unit 3 is formed by alternately arranging a plurality of piezoelectric element drive units (hereinafter referred to as drive units) 14a and columns 14b on a substrate 15, and the drivers 14a and columns 14b are spaced apart from each other by a predetermined distance. It is joined to 15.

  The liquid chamber unit 2 corresponds to a nozzle plate 11 having a plurality of nozzles 40 for discharging the droplets 61, a flow path plate 12 in which an individual liquid chamber 30 to which the nozzles 40 communicate is formed, and an individual liquid chamber 30; In addition, the diaphragm unit 13 is configured to transmit the vibration of the drive unit 14 a of the drive unit 3 to the individual liquid chamber 30.

  The nozzle plate 11, the flow path plate 12, and the diaphragm 13 that constitute the liquid chamber unit 2 apply the adhesive 16 on the upper surface of the flow path plate and are joined with high accuracy via the adhesive 16.

  In addition, the liquid chamber unit 2 is bonded with high precision to the upper surfaces of the piezoelectric element drive portions 14 a and the support portions 14 b of the drive unit 3 via the adhesive 16.

  The liquid discharge head 1 supplies the application liquid from a storage tank (not shown) to fill the individual liquid chamber 30 and selectively drives the drive unit 14 a to discharge droplets 61 from the nozzle 40.

  Here, as shown in FIG. 1 described above with respect to the application target member 51 held by the work stage 54, the liquid discharge head 1 is second in a quadrant in a cross section orthogonal to the rotation center axis of the application target member 51. It is arranged in the quadrant. Thus, the nozzle array in which the plurality of nozzles 40 of the liquid discharge head 1 are arranged is positioned obliquely above the rotation center axis of the application member 51, and the rotation center in the direction along the rotation center axis of the application member It is parallel to the axis, and is further disposed in a state where the discharge direction of the droplets 61 is vertically downward.

  Next, the coating operation in the coating apparatus configured as described above will be described.

  First, a drive waveform to be applied to the piezoelectric element drive unit 14 a necessary for control of vertically depositing the droplets 61 discharged from the liquid discharge head 1 on the coated area 65 of the application member 51 is set.

  The viscosity of the coating liquid discharged as droplets 61 changes with the elapsed time after generation. Therefore, in order to discharge the droplets 61 at a constant droplet velocity and droplet size, the drive waveform applied to the piezoelectric element drive unit 14a is adjusted according to the elapsed time after the formation of the coating solution (for example, the drive voltage is increased Needs to be

  Therefore, the elapsed time after the generation of the coating liquid and the data of the drive waveform are tabulated in advance and stored and held in storage means of a control unit (not shown).

  Next, the rotational speed setting process of the member to be coated will be described with reference to the flow chart of FIG.

  First, the dummy application member 51 to be used for setting the rotational speed is set on the work stage 54 and rotationally driven by the motor 55 at the maximum speed of the coating apparatus.

  Then, the liquid discharge head 1 is driven with a drive waveform and a constant drive frequency corresponding to the elapsed time after the generation of the coating liquid, which correlates with the viscosity of the coating liquid. As a result, the droplets 61 are continuously ejected from the liquid ejection head 1 at a constant frequency and at a constant droplet ejection speed and droplet size.

  At this time, the impact direction of the discharged droplets 61 is measured by the camera 70. If the landing direction of the droplets 61 is not perpendicular (normal direction) to the application surface, the rotational speed of the dummy application member 51 is reduced by a constant speed obtained in advance by experiment or the like.

  Similarly, the measurement of the impact direction of the droplet 61 and the reduction of the rotational speed are repeated until the impact direction of the droplet 61 with respect to the application surface is perpendicular to the application surface (normal direction).

  Then, the rotational speed when the landing direction of the droplets 61 becomes perpendicular to the application surface is stored and stored in the storage unit of the control unit (controller) (not shown).

  Next, control (process) related to the coating operation will be described with reference to the flow charts of FIG. 17 and FIG. 18 and the explanatory views of FIG. 19 to FIG.

  The application member 51 is set on the work stage 54 of the application apparatus, and the motor 55 is driven to set the application member 51 as described above and rotate it at the rotational speed.

  Then, the scanning motor (not shown) starts moving the work stage 54 to a position where droplets are discharged by the liquid discharge head 1 at a set speed determined and set in advance by experiments or the like.

  Thereafter, when the edge 52L (see FIG. 11) of the sensor dog 52 is detected by the trigger sensor 58, as shown in FIG. 19, the coating liquid from the first nozzle 40 (40-1) of the liquid ejection head 1 Discharge of the droplets 61 is started with a drive waveform corresponding to an elapsed time after generation and a fixed discharge cycle (see FIG. 19).

  Then, when the work stage 54 moves by the distance between the nozzles, discharge from the second nozzle 40 (40-2) is started in the discharge cycle. Similarly, while moving the work stage 54 at a constant speed, discharge from the nozzles 40 is sequentially started every movement of the distance between nozzles. An example of the state of the application surface of the application member 51 at this time is shown in FIG. 20 and FIG.

  Thereafter, when the edge 53L of the sensor dog 53 is detected by the trigger sensor 58, the discharge from the first nozzle 40 (40-1) is stopped. Then, when the work stage 54 moves by the distance between the nozzles, the discharge from the second nozzle 40 (40-2) is stopped. Similarly, the discharge of all the nozzles 40 is stopped while the movement of the work stage 54 at a constant speed is continued. An example of the state of the application surface of the application member 51 at this time is shown in FIG.

  Then, the movement of the work stage 54 on the forward path is stopped. As a result, as shown in FIG. 22B, the application liquid is applied to the application member 51 in the forward path.

  Thereafter, the movement of the work stage 54 in the opposite direction (return direction) to the above-described forward direction is started, and the edge 53R (see FIG. 11) of the sensor dog 53 is detected by the trigger sensor 58. Starting from 40-N), the discharge of the droplets 61 is started each time the nozzle distance is moved. Then, similarly, when the edge 52R of the sensor dog 52 is detected by the trigger sensor 58, the ejection of the droplets 61 is sequentially stopped from the last nozzle 40 (40-N) for each movement of the inter-nozzle distance. After the discharge from all the nozzles 40 and the discharge stop are performed, the movement of the work stage 54 in the return path is stopped.

  Thereby, the application is performed on the coating film applied in the forward pass as well as in the forward pass, and the application to the application region 65 of the application member 51 is completed.

  Therefore, the application member 51 is removed from the coating apparatus.

  Next, the operation and effects of the present invention will be described with reference to FIGS.

  Coating was performed on a member to be coated under the following coating conditions using the coating devices of Example 1 and Comparative Examples 12 and 3 in which the following liquid discharge head, coating liquid, and member to be coated were incorporated.

<Liquid discharge head>
One having the head specifications of the shape characteristics / components, the ejection characteristics, and the ink requirement characteristics shown in FIG. 23 was used.
<Coating solution>
Viscosity: 5.06 mPa · s
<Application member>
(1) Outer diameter: φ12.7 mm
(2) Application range: 345 mm
<Painting conditions>
(1) Rotation speed of the object to be coated: 2000 rpm
(2) Object feed speed: 29 mm · s
(3) Head ejection frequency: 6000 Hz
(4) Droplet flight distance discharged from head: 2 mm
(5) Film thickness: 10 μm

Example 1
As shown in FIG. 24A, the liquid discharge head 1 is disposed at a position offset by 3 mm from the normal to the rotation center 0 of the application member 51, and the direction in which the application liquid is discharged is the head 1 and the application member 51. The coating was performed by arranging in a direction toward the rotation direction (direction of arrow B) of the application member 51 from the point where the straight line connecting the rotation centers of these and the application surface of the application member 51 intersects.

Comparative Example 2
As shown in FIG. 24 (b), the coating was performed under the condition that the liquid discharge head 1 was disposed at the normal position of the rotation center 0 of the application member 51. The rotation direction of the application member 51 was the reverse direction (the arrow C direction) to that of the first embodiment.

Comparative Example 3
As shown in FIG. 26, the liquid ejection head 1 is disposed at a position 3 mm offset from the normal to the rotation center 0 of the application member 51, and the direction of ejection of the application liquid is the rotation center of the head 1 and the application member 51. The coating was performed in a direction toward the downstream of the rotational direction of the application member 51 from the point where the straight line connecting the two and the application surface of the application member 51 intersect. That is, the coating was performed by setting the rotation direction of the application member 51 as the reverse direction (the direction of the arrow C) to that of the first embodiment.

  The coating efficiency in Example 1 and Comparative Examples 1 and 2 was calculated by measuring the weight remaining on the coated member 51 based on the weight of the coating liquid required to coat one coated member 51.

First of all,
(1) The discharge was performed under the same conditions as the case where one coating member 51 was coated, and the container received the entire amount of the discharged coating liquid.
(2) The weight difference between the containers before and after the discharge was measured to determine the weight G3 of the discharged coating liquid.
(3) Subsequently, the container containing the coating liquid was placed in a baking furnace, and the weight after baking was measured.
(4) The dry weight G5 of the discharged coating liquid was determined from the difference from the initial weight of the container.

next,
(5) The member to be painted 51 was painted under the three conditions of Example 1, Comparative Example 1 and Comparative Example 2.
(6) The weight difference between before and after painting of the member to be painted 51 was measured, and the weight G31 of the coating liquid applied to the member to be painted 51 was determined.
(7) Then, the to-be-coated member 51 to which the coating liquid was applied was put into a baking furnace, and the weight after baking was measured.
(8) The dry weight G51 of the coating liquid applied to the coated member 51 was determined from the difference from the initial weight of the coated member 51.

And
(9) Calculation of G51 / G5 × 100 (%) was performed to determine the coating efficiency under each condition of Example 1, Comparative Example 1, and Comparative Example 2.

  In addition, since the weight before baking changes under the influence of the volatilization state of a solvent, it is a reference value to the last.

  The application efficiency calculated as described above was 80% in Example 1, 45% in Comparative Example 1, and 15% in Comparative Example 2.

  From this, in Example 1, it can be confirmed that the scattering of the coating liquid is small, and as described above, the application efficiency is very good.

  This is because, as shown in FIG. 25B, the configuration of the first embodiment causes the force P1 by the air flow 301 during the rotation of the application member 51 applied to the droplet 300 and the driving force and gravity of the droplet 300. The resultant force P due to the sum value P2 of Therefore, as indicated by an arrow 303 in FIG. 25A, it is assumed that the ejected droplet 300 stably flies, and is an effect by going straight toward the coated surface of the application member 51. .

  On the other hand, in Comparative Example 1, scattering of the coating solution is larger than in Example 1, and as described above, the coating efficiency is also reduced as compared with Example 1.

  Moreover, in the comparative example 2, it is confirmed that there is much scattering of a coating liquid, and as above-mentioned, a deposition efficiency will be a very bad result.

  This is because, as shown in FIG. 26B, the combined force P by the sum P2 of the force P1 by the air flow 302 applied to the droplet 300 during rotation of the application member 51 and the propelling force of the droplet 300 and gravity is It is oriented in the direction along the peripheral surface of the application member 51, and when the application member 51 has a small diameter and is applied at high speed, airflow around the liquid discharge head 1 and the application member 51 is strongly generated. . Therefore, as indicated by an arrow 304 in FIG. 26A, it is presumed that the discharged droplet 300 gets on the air flow 302 and flows along the circumferential surface of the application member 51 and does not land on the coated surface. .

1 ... liquid ejection head 11 ... nozzle plate 40 ... nozzle 51 ... application member 54 ... work stage 55 ... motor 56 ... holder 57 ... stage 58 ... trigger sensor 61 ... droplet 62 ... mist 67 ... coating droplet after landing

Claims (6)

Liquid discharge means for discharging droplets of the application liquid to the application member;
The liquid discharge means is a member for applying the liquid droplet from the point where the droplet discharge direction intersects the straight line connecting the nozzle that discharges the droplet and the rotation center of the member to be coated and the application surface of the member to be coated. It is arranged in a state where it is directed to the upstream side in the rotational direction,
The coating device according to claim 1, wherein the liquid discharging means is disposed at a position where the droplet lands on a normal to the rotation center of the application member. The coating apparatus according to claim 1, wherein the liquid discharge unit is disposed in a state in which the droplet discharge direction is downward in the gravity direction. The coating apparatus according to claim 1, wherein the liquid discharge unit is disposed in a state in which the droplet discharge direction is a direction directed downward in the gravity direction. The application according to any one of claims 1 to 3, wherein the liquid discharging means is disposed in a state where the nozzle is lower than the highest position of the application member in the gravity direction. apparatus. The coating device according to any one of claims 1 to 4, wherein the nozzle is disposed in a second quadrant when the liquid discharging means sets the rotation direction of the application member clockwise. . A method of applying a coating liquid to a member to be coated by discharging a droplet of the coating liquid from a liquid discharge unit to the member to be coated,
The rotational direction upstream of the application member from the point at which the normal line connecting the nozzle for discharging the liquid droplets from the liquid ejection means and the rotation center of the application member intersects the application surface of the application member A coating method comprising: discharging the droplet with a direction toward the side being a droplet discharge direction, and causing the droplet to land from a normal to the rotation center of the member to be coated.

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