WO2020165987A1

WO2020165987A1 - Electrostatic spraying method and electrostatic spraying device used for electrostatic spraying method

Info

Publication number: WO2020165987A1
Application number: PCT/JP2019/005238
Authority: WO
Inventors: 和昭佐藤; 秀俊石川; 昌大久保
Original assignee: アネスト岩田株式会社
Priority date: 2019-02-14
Filing date: 2019-02-14
Publication date: 2020-08-20

Abstract

Provided are an electrostatic spraying method and an electrostatic spraying device used for the electrostatic spraying method, the electrostatic spraying method comprising: a step for disposing an adsorption electrode (30) of an electrostatic spraying device (10) in a through-hole (50H) of an object (50) to be coated; and a step for generating an electrostatic force for spraying a liquid from a nozzle (22) of the electrostatic spraying device (10) only with the electrostatic force, by applying a voltage between the object to be coated (50) and a liquid spraying unit (20) and between the adsorption electrode (30) and the liquid spraying unit (20), while keeping the object to be coated (50) and the adsorption electrode (30) at the same potential, and spraying the liquid onto the object to be coated (50).

Description

Electrostatic spraying method and electrostatic spraying apparatus suitable for use in the electrostatic spraying method

The present invention relates to an electrostatic spraying method and an electrostatic spraying device suitable for use in the electrostatic spraying method.

Patent Document 1 discloses a method for coating the surface of a stent or the like and an apparatus used for the method.
In Patent Document 1, coating is performed while the nozzle of the dispenser is positioned along the outer surface of the mesh-shaped stent.

JP, 2009-240490, A JP, 2015-192961, A

However, it is very troublesome to apply the coating so that the nozzle of the dispenser is located along the outer surface of the reticulated stent having a very small size. In addition, a tubular shape having a through hole in the length direction such as a stent, and a plurality of holes penetrating from the outer surface to the inner surface defining the through hole are formed on the side wall, easily with respect to the outer surface of the object to be coated. The advent of methods of applying liquids to form coatings is desired.
In addition, it is desired that when applying the liquid, the applied state of the liquid applied to the inner surface can be made appropriate (for example, the state where the liquid is not applied to the inner surface or the state where the coating film has a predetermined film thickness). ..

In addition, as a method of spraying a liquid on a fine portion using only electrostatic force, there is one disclosed in Patent Document 2.
However, as far as the present inventors know, when applying a liquid to a stent or the like by a spraying method of spraying a liquid using only such electrostatic force, the applied state of the liquid applied to the inner surface is also appropriate. I have not found anything that can be done.

The present invention has been made in view of such circumstances, and is a tubular shape having a through hole in the length direction like a stent, and a plurality of sidewalls penetrating from the outer surface to the inner surface defining the through hole. An electrostatic spraying method capable of realizing a desired coating state of the liquid on each of the outer surface and the inner surface when a liquid is applied to an object to be coated with holes, and an electrostatic spraying method suitable for the electrostatic spraying method. An object is to provide a spraying device.

The present invention is grasped by the following configurations in order to achieve the above object.
In the electrostatic spraying method according to the embodiment of the present invention, a cylindrical shape having a through hole in the length direction, and a plurality of holes penetrating from an outer surface to an inner surface defining the through hole is formed on at least one side wall. An electrostatic spraying method for applying a liquid to an object to be coated,
Disposing a conductive or semi-conductive adsorption electrode of an electrostatic spraying device in the through hole of the object to be coated,
While maintaining the same potential as the object to be coated and the adsorption electrode, a voltage is applied between the object to be coated and the liquid spray section of the electrostatic spraying device and between the adsorption electrode and the liquid spray section, Generating the electrostatic force that sprays the liquid only by the electrostatic force from the nozzle of the liquid spraying unit by the voltage, and spraying the liquid toward the object to be coated.

In the arranging step, the adsorption electrode may be arranged in the through hole of the object to be coated so as not to contact the inner surface of the object to be coated.

The article to be coated may be a stent having at least one side wall of a mesh shape, and the liquid may be a solvent in which a biodegradable and absorbable polymer that is decomposed and absorbed in a living body is dissolved.

In the spraying step, the adsorption electrode may form a separation distance between the adsorption electrode and the inner surface where the liquid is not applied to the inner surface.

The electrostatic spraying device of the embodiment of the present invention,
Electrostatic for applying liquid to an object to be coated, which has a cylindrical shape having a through hole in the length direction and has a plurality of holes penetrating from the outer surface to the inner surface defining the through hole on at least one side wall. A spraying device,
The electrostatic spraying device,
A liquid spray section having a nozzle,
Located in the through-hole, a conductive or semi-conductive adsorption electrode,
While the potentials of the object to be coated and the adsorption electrode are the same, a voltage is applied between the object to be coated and the liquid spraying section and between the adsorption electrode and the liquid spraying section, and the voltage causes the nozzle to eject the liquid. Voltage applying means for generating an electrostatic force for spraying the liquid only by the electrostatic force.

The adsorption electrode may have a cross-sectional size of a portion arranged in the through hole of the object to be coated so as not to contact the through hole of the object to be coated.

The length of the adsorption electrode is preferably longer than the length of the article to be coated.

The adsorption electrode has a size such that a size of a cross section of a portion of the object to be coated, which is disposed in the through hole, forms a separation distance between the adsorption electrode and the inner surface for not applying the liquid to the inner surface. May be

According to the present invention, a liquid is applied to an article to be coated, which has a cylindrical shape having a through hole in the length direction such as a stent, and in which a plurality of holes penetrating from the outer surface to the inner surface defining the through hole is formed on the side wall. When applying, it is possible to achieve a desired application state of the liquid on each of the outer surface and the inner surface.

It is a perspective view for explaining the electrostatic spraying device of the first embodiment according to the present invention. It is sectional drawing which showed only the liquid spraying part of 1st Embodiment which concerns on this invention. FIG. 3 is an enlarged cross-sectional view of the tip end side of the liquid spraying portion of FIG. 2, showing the case where the tip end surface of the mandrel is located rearward. FIG. 3B is an enlarged cross-sectional view of the tip side of the liquid spraying portion of FIG. 2, showing the case where the tip end surface of the mandrel is located forward of the state of FIG. 3A. FIG. 3 is a plan view showing only the adsorption electrode, the support portion, the holding portion, and the article to be coated according to the first embodiment of the present invention. It is a perspective view showing only an adsorption electrode, a supporting part, a holding part, and an article to be coated of a 1st embodiment concerning the present invention. It is a figure for demonstrating the state when the liquid sprayed from the nozzle of 1st Embodiment which concerns on this invention applies to a to-be-coated material, and is a figure which shows the case where an adsorption electrode is provided in a to-be-coated material. Is. It is a figure for demonstrating the state when the liquid sprayed from the nozzle of 1st Embodiment which concerns on this invention apply|coats to a to-be-coated object, when the adsorption electrode is not provided in the to-be-coated object. FIG.

Hereinafter, modes (hereinafter, embodiments) for carrying out the present invention will be described in detail with reference to the accompanying drawings.
The same elements are denoted by the same numbers or reference numerals throughout the description of the embodiments.

Unless otherwise specified, expressions such as “tip (edge)” and “front (edge)” indicate the direction of liquid spray in each member, and “rear (edge)” and “rear (edge)”. The expression such as “” represents the side opposite to the liquid spray direction in each member or the like.

(First embodiment)
FIG. 1 is a perspective view for explaining an electrostatic spraying device 10 of a first embodiment according to the present invention.
In the present embodiment, the object to be coated 50 has a tubular shape having a through hole 50H (see FIG. 5) in the length direction, and has a plurality of holes penetrating from the outer surface to the inner surface defining the through hole 50H on the side wall. As a typical example of the case of a medical stent having a cylindrical shape having a through hole 50H in the length direction and a mesh-shaped side wall, liquid is not applied to the inner surface of the stent while liquid is applied to the outer surface. Will be described to form a coating on the outer surface of the stent.

For example, in the case of a medical coronary stent, the inner diameter is about 2.25 mm to 4.00 mm, and the outer diameter is 2.75 mm to 4.50 mm (that is, the thickness of the material forming the stent is about 0.25 mm). ), and the length is approximately 8.00 mm or more and 38.00 mm or less, which is extremely fine.
However, in the drawings, the article to be coated 50 (medical stent), the adsorption electrode 30, and the like are shown in a larger size with respect to the liquid spray portion 20 so that the state of the stent or the like can be easily understood.

When a coating is formed on the outer surface of such a medical stent, the liquid used is a solvent in which a biodegradable and absorbable polymer that is decomposed and absorbed in vivo is dissolved. Typical examples thereof include poly-L-lactic acid (PLLA), poly-DL-lactic acid (PDLLA) and polycaprolactone (PCL), but the invention is not limited thereto.

The object 50 to be coated is not limited to a medical stent, but has a tubular shape having a through hole 50H in the longitudinal direction, and penetrates at least one side wall from the outer surface to the inner surface defining the through hole 50H. It is only necessary that a plurality of holes are formed, and in this case, a liquid such as a paint is also used according to the object 50 to be coated.

As shown in FIG. 1, the electrostatic spraying device 10 includes a liquid spraying section 20 having a nozzle 22, a semiconductive conductive electrode having a conductive or surface resistance of 10 ¹⁰ Ω or less, an article to be coated 50, and a liquid. A voltage application unit 40 that applies a voltage between the spray units 20 and between the adsorption electrode 30 and the liquid spray unit 20 is provided.

The voltage applying means 40 includes a voltage power supply 41, a first electric wiring 42 that electrically connects one electrode of the voltage power supply 41 and the liquid spraying section 20, and a suction electrode 30 that allows the suction electrode 30 to rotate and slide. A conductive supporting portion 43 having a receiving portion 43a for receiving one end side and supporting the adsorption electrode 30, and a second electric wiring 44 for electrically connecting the other electrode of the voltage power supply 41 and the supporting portion 43. And a holding unit 45 that holds the adsorption electrode 30 and the article to be coated 50 rotatably, and electrically connects the adsorption electrode 30 and the article to be coated 50 (sometimes referred to as a short circuit).
The holder 45 will be described later in detail.

Then, the adsorption electrode 30 is arranged so as to come into contact with the support portion 43 electrically connected to the other electrode of the voltage power supply 41 by the second electric wiring 44, so that the support portion 43 and the adsorption electrode 30 are separated from each other. Since the adsorption electrode 30 and the article to be coated 50 are short-circuited in the holding portion 45 as well as the short-circuited state, the voltage power supply 41 causes a space between the adsorption electrode 30 and the liquid spraying section 20 and between the article to be coated 50 and the liquid sprayer. When a voltage is applied between the parts 20, the article to be coated 50 and the adsorption electrode 30 have the same potential.

Therefore, the voltage applying unit 40 applies a voltage between the object 50 to be coated and the liquid spraying section 20 and between the adsorption electrode 30 and the liquid spraying section 20 while keeping the object 50 to be coated and the adsorption electrode 30 at the same potential. It has become a thing.
However, the voltage application means 40 is not limited to the above-described configuration, and the object 50 to be coated and the adsorption electrode 30 are kept at the same potential while the object 50 to be coated and the liquid spraying section 20 and between the adsorption electrode 30 and the liquid spraying section 20. Any voltage may be applied between the two.

In the present embodiment, the electrostatic spraying device 10 includes the grounding means 46, and the second electric wiring 44 is connected to the grounding means 46. Therefore, the article to be coated 50 and the attraction electrode 30 are grounded. It has become.
Although the grounding means 46 is not an indispensable requirement, a worker may touch the article 50 to be coated. Therefore, from the viewpoint of safety, the grounding means 46 is provided to ground the article 50 to be coated. It is preferable.

Then, although a method of spraying the liquid will be described later, the voltage application unit 40 sets the potentials of the article to be coated 50 and the adsorption electrode 30 to the first potential that is the same potential, and the voltage of the liquid spraying unit 20. When the electric potential is the second electric potential, the electric potential difference between the first electric potential and the second electric potential causes an electrostatic force for spraying the liquid from the nozzle 22 only by the electrostatic force between the object to be coated 50 and the liquid spraying unit 20 and the adsorption electrode 30. A voltage is applied between the article to be coated 50 and the liquid spraying section 20 and between the adsorption electrode 30 and the liquid spraying section 20 so that the potential difference is generated between the liquid spraying section 20 and the liquid spraying section 20.

(Liquid spray part)
FIG. 2 is a cross-sectional view showing only the liquid spraying unit 20, and also illustrates a state in which the liquid is sprayed from the liquid spraying unit 20 as described later.

As shown in FIG. 2, the liquid spraying section 20 includes a body portion 21 made of an insulating material in which a liquid flow path 21b having a liquid supply port 21a for supplying a liquid is formed, and a liquid flow of the through hole having the body portion 21. A nozzle 22 provided at the tip of the body portion 21 so as to communicate with the passage 21b, and a mandrel 23 made of a conductive material arranged in the liquid flow passage 21b of the body portion 21 and in the through hole of the nozzle 22 are provided. There is.

The body portion 21 is provided with a hole portion 21c communicating with the liquid flow path 21b in order to take out the mandrel 23 to the rear end side, and a gap between the mandrel 23 is sealed in the hole portion 21c. A seal member 24 is provided to prevent liquid from leaking.
Although the O-ring is used as the seal member 24 in the present embodiment, the seal member 24 is not limited to the O-ring, and any sealable member may be used.

Further, a knob 23a made of an insulating material is provided at the rear end of the mandrel 23 located on the rear end side of the body 21 through the hole 21c, and is provided so as to penetrate almost the center of the knob 23a. An electric wiring connecting portion 23b made of the conductive material is provided.

As shown in FIG. 1, the electric wire connecting portion 23b is connected to the first electric wire 42 of the voltage applying means 40, and the electric wire connecting portion 23b is brought into contact with the mandrel 23 so that the mandrel 23 is electrically connected to the mandrel 23. The wiring connection portion 23b is electrically connected.

In the present embodiment, the mandrel 23 is used as the electrode on the liquid spraying section 20 side. However, for example, the nozzle 22 of the liquid spraying section 20 is made of a conductive material, and the first electricity of the voltage applying means 40 is applied to the nozzle 22. The nozzle 22 may be used as an electrode on the liquid spraying section 20 side so that the wiring 42 is connected.

In addition, as shown in FIG. 2, a female screw structure 21e for screw-connecting the knob 23a is provided on the inner peripheral surface of the rear end opening 21d of the body portion 21, while the tip of the knob 23a is provided. A male screw structure 23c is provided on the outer peripheral surface.

Therefore, the mandrel 23 is detachably attached to the body portion 21 by screwing the male screw structure 23c on the outer peripheral surface of the tip end of the knob portion 23a into the female screw structure 21e of the rear end opening 21d of the body portion 21.
Further, the mandrel 23 can be moved in the front-rear direction by adjusting the screwing amount of the knob 23a, and the position of the distal end surface 23d of the mandrel 23 can be adjusted in the front-rear direction.

In order to satisfactorily spray the liquid only with the electrostatic force, it is difficult to make the opening 22b of the nozzle 22 have a too large diameter, so that clogging may occur, but as described above, the mandrel 23 is used. Since the nozzle can be moved in the front-rear direction, even if the nozzle 22 is clogged, the clog can be eliminated by moving the mandrel 23.

3A and 3B are enlarged views in which the tip end side of the liquid spraying section 20 is enlarged, FIG. 3A shows a case where the tip end surface 23d of the mandrel 23 is located rearward, and FIG. 3B shows the state of FIG. 3A. This is also the case where the tip surface 23d of the mandrel 23 is located in the front.

As shown in FIG. 3A, the nozzle 22 has a tapered inner diameter portion (see range W1) in which the inner diameter is tapered toward the opening 22b side and the taper angle is α, and the mandrel 23 has a tip. It has a tapered portion (see range W2) in which the outer diameter decreases toward the surface 23d and the taper angle is β.

The taper angle α of the tapered inner diameter portion of the nozzle 22 is larger than the taper angle β of the tapered portion of the mandrel 23.
Further, the diameter of the front end surface 23d of the mandrel 23 is set to be smaller than the opening diameter of the opening 22b of the nozzle 22, but the tapered portion of the mandrel 23 gradually increases in diameter toward the rear end side. Therefore, the nozzle 22 is formed to have a portion having a diameter larger than the opening diameter of the opening 22b.

As described above, by forming the tip end side of the nozzle 22 and the mandrel 23, the nozzle 22 and the mandrel 23 are formed by moving the mandrel 23 in the front-rear direction, as can be seen by comparing FIGS. 3A and 3B. The width of the gap can be adjusted, and the amount of liquid discharged from the opening 22b of the nozzle 22 can be adjusted.

Further, by moving the mandrel 23 further to the front side than in the state shown in FIG. 3B, it is possible to bring the mandrel 23 into contact with the inner peripheral surface of the nozzle 22 and close the opening 22b of the nozzle 22.
Therefore, in a state where the liquid is not sprayed, the opening 22b of the nozzle 22 can be closed by the mandrel 23 and the liquid in the nozzle 22 can be prevented from drying, so that clogging of the nozzle 22 can be suppressed.

(Basic spray state of liquid)
Next, with reference to FIG. 2, first, a basic state in which the liquid is sprayed from the liquid spraying section 20 will be described, and then a state in which the liquid is applied to the article 50 will be described.

The liquid supplied to the liquid supply port 21a of the body portion 21 is supplied to the tip end side of the nozzle 22, and is applied between the object to be coated 50 and the mandrel 23 and the adsorption electrode 30 by the voltage applying means 40 (see FIG. 1). And the mandrel 23 are generated by a voltage applied between the object to be coated 50 and the mandrel 23 and between the adsorption electrode 30 and the mandrel 23. Atomize.

The state in which the liquid is separated and atomized will be described more specifically. As shown in FIG. 2, the liquid is separated from the tip surface 23d of the mandrel 23 and the outer peripheral edge 22a of the nozzle 22 by the surface tension and the adhesive force due to the viscosity. On the other hand, when the electrostatic force pulling the liquid forward balances, the liquid supplied to the tip side of the nozzle 22 forms a Taylor cone 60 having a conical shape at its tip.

The Taylor cone 60 is formed by the action of an electric field so that positive/negative charges are separated in the liquid, and the meniscus at the tip of the nozzle 22 charged with excess charges is deformed into a conical shape.
Then, the liquid is pulled straight from the tip of the Taylor cone 60 by the electrostatic force, electrostatic explosion occurs at the tip, and the liquid is separated/atomized, that is, atomized.

The sprayed liquid, that is, the liquid that has separated from the nozzle 22 and has become liquid particles has a dramatically larger area in contact with air than in the state before separation, so that vaporization of the solvent is promoted and the solvent Due to vaporization, the distance between charged electrons comes closer, and electrostatic repulsion (electrostatic explosion) occurs, causing the liquid particles to divide into smaller particles.

When this fragmentation occurs, the surface area in contact with air increases more than before the fragmentation, which accelerates the vaporization of the solvent and causes electrostatic explosion in the same manner as described above. Split into particles.
The liquid thus sprayed by the electrostatic explosion from the nozzle 22 is further atomized by repeating the electrostatic explosion even after spraying, and further atomization is promoted, and the liquid is applied to the object 50 to be coated in an extremely small particle state. become.

Next, after describing the configuration of the electrostatic spraying device 10 on the side of the article 50 to be coated, the state in which the liquid sprayed from the nozzle 22 is applied to the article 50 to be coated as described above will be described. ..

FIG. 4 is a plan view showing only the adsorption electrode 30, the support portion 43, the holding portion 45 and the article 50 to be coated, and FIG. 5 shows only the adsorption electrode 30, the support portion 43, the holding portion 45 and the article 50 to be coated. FIG.
Note that FIG. 4 is a plan view seen from the upper side.

As shown in FIGS. 4 and 5, the support portion 43 includes a first main body portion 43A in which a receiving portion 43a formed of a U-shaped notch opened to the upper side is formed, and both sides of the first main body portion 43A. And a pair of first mounting portions 43B provided so as to project from the first main body portion 43A and having screw holes 43b through which a screw for screw fixing is mounted on a mounting table (not shown).

Further, as shown in FIGS. 4 and 5, the holding unit 45 holds the adsorption electrode 30 and the article to be coated 50, and is provided with a rotation holding section 45 a that rotates together with the adsorption electrode 30 and the article to be coated 50. A main body portion 45A and screw holes 45b are provided on both sides of the second main body portion 45A so as to project from the second main body portion 45A, and a screw hole 45b for inserting a screw when fixing the screw on a mounting table (not shown) is formed. And a pair of second mounting portions 45B.

Then, as shown in FIG. 1, when the holding portion 45 holds the adsorption electrode 30, the one end portion side of the adsorption electrode 30 has a positional relationship such that it can be received by the receiving portion 43 a of the support portion 43. The support part 43 and the holding part 45 are fixed by screws on a mounting table (not shown) so that the support part 43 and the holding part 45 are located.
An insulating material is used, for example, in the portion where the support portion 43 and the holding portion 45 of the mounting table (not shown) are fixed.

The rotation holding portion 45a is fixed to the bearing portion 45aa (for example, a ball bearing) fixed to the center of the second main body portion 45A and the first through hole 45H1 in the center of the bearing portion 45aa by press fitting or the like, and the adsorption electrode 30 is It is provided with a cylindrical fitting portion 45ab having a second through hole 45H2 to be fitted, and a first holding body 45ac provided on the other side of the fitting portion 45ab and holding the article 50 to be coated.
Since the fitting portion 45ab is made of a conductive material, the suction electrode 30 is fitted to the fitting portion 45ab, and the fitting portion 45ab and the suction electrode 30 are brought into contact with each other, whereby the fitting portion 45ab. Is in a state of being electrically connected to the adsorption electrode 30 (sometimes called a short circuit).

As shown in FIG. 4, the fitting portion 45ab is provided so as to penetrate the second main body portion 45A when seen in a plan view from above, and the fitting portion 45ab protruding from the second main body portion 45A to one side. The end surface 45ab1 of the joining portion 45ab is a receiving surface for receiving the position restricting portion 31a of the adsorption electrode 30 described later.

Further, the fitting portion 45ab has an annular step along the outer periphery of the second through hole 45H2 into which the adsorption electrode 30 is fitted, on the end surface 45ab2 of the fitting portion 45ab protruding from the second main body portion 45A to the other side. The cylindrical first holding body 45ac made of an insulating material that holds one side of the through hole 50H (see FIG. 5) of the article to be coated 50 is press-fitted or the like into the stepped portion. It is fixed.

In the first holding body 45ac, the diameter (also referred to as the inner diameter) of the third through hole at the center is almost the same as the diameter (also referred to as the inner diameter) of the second through hole 45H2 (see FIG. 5) of the fitting portion 45ab. It has the same diameter.
Further, the first holding body 45ac has an outer diameter smaller than the outer diameter of the fitting portion 45ab, and specifically, the first holding body 45ac has a diameter (called an inner diameter) of the through hole 50H of the article 50 to be coated. In some cases, the outer diameter is approximately equal to or slightly larger than that.

Then, the first holding body 45ac is fixed to the fitting portion 45ab such that the central axis of the third through hole is coaxial with the central axis of the second through hole 45H2 of the fitting portion 45ab.
Specifically, as described above, the first holding body 45ac includes the step portion formed on the end surface 45ab2 on the other side of the fitting portion 45ab from the end surface 45ab2 on the other side of the fitting portion 45ab to the other side. The outer diameter of the first holding member 45ac is smaller than the outer diameter of the fitting portion 45ab.

Although the reason will be described later, the amount of projection (projection length) from the other end surface 45ab2 of the fitting portion 45ab of the first holding body 45ac is the minimum necessary for holding the article to be coated 50. It's length.

Therefore, the other end surface 45ab2 of the fitting portion 45ab is present on the outer circumference of the first holding body 45ac, and the one end portion 50a of the article 50 is the other end surface 45ab2 of the fitting portion 45ab. When the article to be coated 50 is attached to the rotation holding portion 45a so that the first holding body 45ac is inserted into the through hole 50H of the article to be coated 50 until it comes into contact with the rotation holding portion 45a, as described above, the fitting portion 45ab becomes Since it is made of a conductive material, the attraction electrode 30 fitted to the fitting portion 45ab and the article 50 to be coated are short-circuited via the fitting portion 45ab.

On the other hand, the adsorption electrode 30 is provided on one side, and has a first rod-shaped portion 31 having an outer diameter larger than the diameter of the second through hole 45H2 of the fitting portion 45ab, and the other end from the other end surface of the first rod-shaped portion 31. And a second rod-shaped portion 32 having an outer diameter substantially equal to the diameter of the second through hole 45H2 of the fitting portion 45ab, and extending from the other end surface of the second rod-shaped portion 32 to the other side. And a third rod-shaped portion 33 having an outer diameter smaller than the diameter of the through hole 50H of the coating material 50.

Since the outer diameter of the second rod-shaped portion 32 is smaller than that of the first rod-shaped portion 31, the other end surface of the first rod-shaped portion 31 exists on the outer periphery of the second rod-shaped portion 32, and A position where the end surface abuts the end surface 45ab1 of the fitting portion 45ab and regulates the insertion position when the suction electrode 30 is inserted into the second through hole 45H2 in order to fit the adsorption electrode 30 into the fitting portion 45ab. It functions as the regulation unit 31a.

In addition, in the present embodiment, the electrostatic spraying device 10 includes a second holding body 47 that is attached to the other end of the adsorption electrode 30 and is formed of an insulating material that holds the article 50 to be coated. ..
Specifically, the second holding body 47 has a holding end portion 47a whose outer diameter on one side is substantially equal to or slightly larger than the diameter of the through hole 50H of the article to be coated 50, and the other holding end portion 47a. And a stop portion 47b extending from the side and having an outer diameter larger than the outer diameter of the holding end portion 47a and the diameter of the through hole 50H of the article 50 to be coated.

The stopper 47b abuts on the other end 50b of the object 50 to be coated, has a function of stopping the movement of the object 50 to the other side, and a gap between the adsorption electrode 30 and the object 50 to be coated. Fulfill the function of keeping.
Although the reason will be described later, the protruding amount (length) of the holding end portion 47a from the stopper portion 47b is set to a minimum length necessary to hold the article 50 to be coated.

The second holding body 47 has a fourth through hole 47c at the center, which has a diameter substantially equal to the outer diameter of the third rod-shaped portion 33 of the adsorption electrode 30, and is fitted into the third rod-shaped portion 33. It can be fixed.

Therefore, after the adsorption electrode 30 and the article to be coated 50 are held by the rotation holding portion 45a, the other end of the article to be coated 50 is further held so that the holding end portion 47a of the second holding body 47 holds the article to be coated 50. While inserting the holding end portion 47a of the second holding body 47 into the through hole 50H from the side, the second holding body 47 is fitted to the third rod-shaped portion 33 of the adsorption electrode 30, and the second holding body 47 is attached to the adsorption electrode. It can be fixed with respect to 30, and when it is fixed in this way, as shown in FIG. 1, the object 50 to be coated is rotatably held together with the adsorption electrode 30 in the holding portion 45.
As described above, when fixing the second holding body 47 to the adsorption electrode 30, the stop portion 47b of the second holding body 47 is brought into contact with the other end 50b of the article 50 to be coated.

By the way, although the reason will be described later, the outer diameter of the third rod-shaped portion 33 of the adsorption electrode 30, which is located in the through hole 50H of the article to be coated 50, is larger than the diameter of the through hole 50H of the article to be coated 50. More specifically, the size of the cross section of the third rod-shaped portion 33 is limited to a size that can be arranged in the through hole 50H so as not to sufficiently contact the through hole 50H of the article 50 to be coated.

For example, the outer diameter of the third rod-shaped portion 33 of the adsorption electrode 30 is a through hole of the article to be coated 50 so that a gap larger than the thickness of the liquid adhering to the article to be coated 50 is formed between the third rod-shaped portion 33 and the article to be coated 50. The diameter is made smaller by 0.1 mm or more with respect to the diameter of 50H so that the object to be coated 50 is not caught when the adsorption electrode 30 is pulled out.

However, as can be seen from the fact that when the outer diameter of the third rod-shaped portion 33 of the adsorption electrode 30 is reduced, the state similar to that without the third rod-shaped portion 33 of the adsorption electrode 30 is gradually approached. If the outer diameter of the third rod-shaped portion 33 of 30 is too small and the separation distance between the third rod-shaped portion 33 of the adsorption electrode 30 and the inner surface of the through hole 50H of the coating object 50 becomes too large, the coating object The liquid is applied to the inner surface of the through hole 50H of 50.
For this reason, the outer diameter of the third rod-shaped portion 33 of the adsorption electrode 30 is set to a small separation distance such that the liquid is not applied to the inner surface of the through hole 50H of the article 50 to be coated.

Next, a state in which the liquid sprayed from the nozzle 22 is applied to the article 50 to be coated will be described.
6A and 6B are views for explaining a state in which the liquid sprayed from the nozzle 22 is applied to the article 50 to be coated, and FIG. 6A shows the adsorption electrode 30 (more specifically, inside the article 50 to be coated). 6B is a diagram showing a case where the third rod-shaped portion 33) is provided, and FIG. 6B shows a case where the adsorption electrode 30 (more specifically, the third rod-shaped portion 33) is not provided in the article 50 to be coated. FIG.

6A and 6B, the trajectory L of the liquid particles sprayed from the nozzle 22 and reaching the article 50 to be coated is schematically shown by a solid line and a dotted line, and the solid line is the stent 50 to be coated. Is a trajectory L of a liquid particle advancing toward the position of a hole penetrating in the side wall of the same, and a dotted line is a trajectory L of the liquid particle advancing so as to collide with the outer surface of the side wall of the stent or the like.

As described above, the liquid is so strongly charged that it is sprayed from the nozzle 22 by the electrostatic explosion, and thus is strongly attracted to the object 50 side by the electrostatic force.
For example, as shown in FIGS. 6A and 6B, even if the liquid particles have passed through the left and right outer sides (upper and lower outer sides in the state of FIG. 1) of the article to be coated 50 in FIGS. 6A and 6B, The liquid particles are strongly attracted to the object 50 side as they are attracted to the side.

Therefore, the liquid can be applied to the entire side wall of the object 50 in the circumferential direction without rotating the object 50, but the entire side wall of the object 50 in the circumferential direction can be applied. In order to uniformly apply the liquid to the target object 50, in the present embodiment, by rotating the rotation holding unit 45a (see FIG. 4), the liquid is applied to the target object 50 while rotating the adsorption electrode 30 and the target object 50. I'm trying to apply it.

Specifically, the rotation shaft of the motor and the fitting portion 45ab of the rotation holding portion 45a are connected by a belt so that the rotational force of the rotation shaft of the motor is transmitted to the fitting portion 45ab to rotate the rotation portion. By rotating the holding portion 45a, the adsorption electrode 30 and the article 50 to be coated are rotated.

However, the method of rotating the rotation holding portion 45a is not limited to transmitting the rotational force of the motor by the belt, but may be transmitted by a gear or the like, and the power source for generating the rotational force is the motor. It may be other than.

On the other hand, some of the liquid particles that are strongly attracted to the object 50 side are directed toward the position of the hole penetrating inside the side wall, and such liquid particles pass through the hole by force. However, it penetrates into the inside of the article 50 to be coated.

Since the liquid particles that have entered the inside of the article to be coated 50 are attracted toward the article to be coated 50 by the electrostatic force, as shown in FIG. 6B, the adsorption electrode 30 (more specifically, the inside of the article to be coated 50) is formed. If the third rod-shaped portion 33) does not exist, the inner surface of the article to be coated 50 will be coated.

On the other hand, as shown in FIG. 6A, when the adsorption electrode 30 (more specifically, the third rod-shaped portion 33) kept at the same potential as the coating object 50 is present in the through hole 50H of the coating object 50, adsorption is performed. Since the electrode 30 itself serves as a target to which liquid particles are applied, like the object 50 to be coated, the liquid particles that have passed through the holes in the side walls are adsorbed by the adsorption electrode 30 and applied to the inner surface of the object 50 to be coated. Is suppressed.

Further, since the adsorption electrode 30 does not come into contact with the inner surface of the article to be coated 50 as described above, when the adsorption electrode 30 is detached after the liquid spraying work is completed, It is possible to prevent the adsorbed liquid from adhering to the inner surface of the article 50 to be coated.

Further, since the object 50 to be coated and the adsorption electrode 30 have the same potential, it is possible to avoid the occurrence of sparks between the object 50 to be coated and the adsorption electrode 30 which are located close to each other.

On the other hand, as described above, since the second holding body 47 and the first holding body 45ac are formed of the insulating material, the surface thereof is also charged by the generated electrostatic force and repels the charged liquid particles. It is ready to go.
Therefore, in the portion where the holding end portions 47a of the first holding body 45ac and the second holding body 47 are inserted into the article 50 to be coated, the liquid particles toward the holes of the article 50 to be coated are repulsed by the repulsive force. Will be pushed back.

However, even if it is made of an insulating material, it may not be able to repel the liquid particles satisfactorily depending on the conditions such as humidity, and the liquid particles may be applied to the holding ends 47a of the first holding body 45ac and the second holding body 47. Then, when the article 50 to be coated is removed, the liquid adheres to the inner surface of the article 50 to be coated. Therefore, as described above, the holding ends 47a of the first holding body 45ac and the second holding body 47 are The length of the article to be coated 50 is limited to the minimum length required to hold it.

It should be noted that when the adsorption electrode 30 has a short length and there is a portion where the adsorption electrode 30 does not exist when viewed in the longitudinal direction of the article to be coated 50, the portion where the adsorption electrode 30 does not exist is shown in FIG. 6B. Since the liquid becomes attached to the inner surface of the article 50 to be coated, it is preferable that the length of the adsorption electrode 30 is longer than the length of the article 50 to be coated.

As described above, in the adsorption electrode 30 of the present embodiment, the outer diameter of the portion of the adsorption electrode 30 arranged in the through hole 50H of the article 50 to be coated is such that the liquid is not applied to the inner surface of the article 50 to be coated. The outer diameter is set so that the separation distance between the adsorption electrode 30 and the inner surface of the article 50 is reduced.

When the article 50 to be coated is a medical stent as in the present embodiment, the through hole 50H has a circular shape, but when the article 50 to be coated is other than the stent, the through hole 50H is Not necessarily circular.

In other words, in the present embodiment, in the case of the present embodiment, the adsorption electrode 30 has a cross-sectional size of a portion of the adsorption object 30 arranged in the through hole 50H of the object 50 to be coated with the liquid. Therefore, the size is set to be a separation distance between the adsorption electrode 30 and the inner surface of the object 50 to be coated so as not to apply the inner surface.

Then, such an adsorption electrode 30 is arranged in the through hole 50H of the article 50 to be coated, and while keeping the article 50 and the adsorption electrode 30 at the same potential, between the article 50 and the liquid spraying section 20 and Between the adsorption electrode 30 and the liquid spraying section 20, a voltage is applied from the nozzle 22 of the liquid spraying section 20 to generate an electrostatic force for spraying the liquid only by the electrostatic force, and the liquid is applied toward the object 50 to be coated. By spraying the liquid, it is possible to easily apply the liquid to the outer surface of the article to be coated 50 while preventing the liquid from being applied to the inner surface of the article to be coated 50. It is suitable when a state in which almost no liquid is applied to the liquid is required to be applied to the liquid.

In this manner, the liquid is applied to the inner surface of the article to be coated 50 having a cylindrical shape having the through hole 50H in the lengthwise direction and having the plurality of holes penetrating from the outer surface to the inner surface defining the through hole 50H on the side wall. The electrostatic spraying method for applying the liquid to the outer surface of the article to be coated 50 without applying it is not limited, but in a stent or the like, it may not be desired to apply the liquid to the inner surface. In the electrostatic spraying method of the present embodiment, when the article 50 to be coated is a type of stent that does not require application of liquid to the inner surface, the outer surface of the mesh-like side wall of the stent is decomposed and absorbed by the solvent in vivo. It is particularly suitable for applying a liquid in which a biodegradable and absorbable polymer is dissolved.

The holding part 45 described in the above embodiment holds the article 50 to be coated, and is arranged in the through hole 50H of the article 50 to prevent the adsorption electrode 30 from coming into contact with the article 50. This is only an example, and for example, a configuration for holding the article to be coated 50 and a configuration for disposing the adsorption electrode 30 in the through hole 50H of the article to be coated 50 so as not to contact the article to be coated 50 It may be provided separately.

Further, depending on the method of holding the adsorption electrode 30, there is no problem even if the adsorption electrode 30 is a rod-shaped body whose outer diameter does not change in the lengthwise direction. Accordingly, the adsorption electrode 30 may have a polygonal shape such as a rectangular shape in cross section.

In addition, the target article 50 to be coated is also tubular with a through hole 50H in the length direction, and has a plurality of holes formed in the side wall from the outer surface to the inner surface defining the through hole 50H. It is sufficient that the cylindrical shape does not need to be cylindrical.
That is, the article to be coated 50 is a tubular body having a polygonal shape such as a rectangular outer shape, and a plurality of holes penetrating from the outer surface to the inner surface defining the through hole 50H is formed on the side wall thereof. It may be.

(Second embodiment)
In the first embodiment, the case where the liquid is not applied to the inner surface of the article 50 to be coated has been described. However, in a medical stent or the like, the liquid is applied to the inner surface and the biodegradable and absorbable polymer is also applied to the inner surface. In some cases, it may be required to form a layer of

Here, if the adsorption electrode 30 is not provided, it is possible to apply the liquid to the inner surface of the article 50 as described above with reference to FIG. 6B.
However, in this case, the amount of the liquid to be applied to the inner surface of the article to be coated 50 is determined according to the condition for applying the liquid to the outer surface of the article to be coated 50, and the application of the liquid to the inner surface is decided. It is difficult to control the amount (coating thickness).

On the other hand, by using the adsorption electrode 30, it is possible to control the amount of liquid applied to the inner surface of the article 50 (thickness of the coating film), and to properly adjust the liquid applied state to the inner surface. It can be anything.

Therefore, in the following, as the second embodiment, the adsorption electrode 30 is used to control the amount of the liquid applied to the inner surface of the object 50 to be coated so that the liquid is applied to the inner surface of the object 50. The case of applying will be described.

Note that, also in the second embodiment, the configuration of the electrostatic spraying device 10 is almost the same as that in the first embodiment, and therefore, the following description will be made mainly regarding different points, and the same points as in the first embodiment will be described. May be omitted.

In the first embodiment, as described with reference to FIGS. 4 and 5, the rotation holding portion 45a includes the first holding body 45ac that holds the article to be coated 50 provided on the other side of the fitting portion 45ab. Although provided, in the second embodiment, the first holding body 45ac is omitted, and the one end 50a of the article 50 is merely in contact with the other end surface 45ab2 of the fitting portion 45ab. To be in a state.
A specific method for rotatably holding the article to be coated 50 by omitting the first holding body 45ac will be described later.

In addition, in the first embodiment, the second holding body 47 includes the holding end portion 47a, but the holding end portion 47a is also omitted, and the second holding body has only the stopping portion 47b. The other end 50b of the article 50 is only in contact with the stopper 47b.

Then, when the second holding body 47 is fitted and fixed to the third rod-shaped portion 33 of the adsorption electrode 30, the object 50 to be coated is slightly moved so that the object 50 does not deform. Fix so as to press in the direction of.
By doing so, the article 50 is rotatably sandwiched between the fitting portion 45ab and the second holding body 47 together with the fitting portion 45ab.
As described above, since the first holding body 45ac and the holding end portion 47a are omitted, the liquid is applied to the inner surfaces of both ends of the article 50 by these as in the first embodiment. Is not disturbed.

However, as described above, since the holding of the article to be coated 50 is a holding with a force that does not deform the article to be coated 50, the article to be coated 50 can be held like the first embodiment. If it is arranged in the horizontal direction, the article 50 to be coated may move during rotation.

Therefore, in the second embodiment, the article 50 is arranged in the vertical direction such that the second holding body 47 is located on the lower side in the vertical direction and the holding portion 45 and the support portion 43 are located on the upper side in the vertical direction. I am trying to do it.

Then, the outer diameter of the third rod-shaped portion 33 of the adsorption electrode 30 is made smaller than that in the first embodiment, and the separation distance between the third rod-shaped portion 33 of the adsorption electrode 30 and the article 50 is increased. To do so.

In FIG. 6B, for the sake of clarity, it is illustrated that the liquid particles that have penetrated into the through holes 50H of the article to be coated 50 are applied to the inner surface facing the invading side. Among the invading liquid particles, the liquid particles having a low invasion speed are attracted to and adhere to the inner surface of the article to be coated 50 existing near the invading portion.
It should be noted that the attraction and coating on the inner surface of the article to be coated 50 existing near the invaded portion in this manner may be referred to as return adhesion hereinafter.

In the first embodiment, the outer diameter of the third rod-shaped portion 33 of the adsorption electrode 30 is large, and the surface of the third rod-shaped portion 33 of the adsorption electrode 30 is close to the inner surface of the article to be coated 50. Liquid particles having a slow penetration speed are also adsorbed by the adsorption electrode 30, so that back adhesion does not occur and the liquid particles are prevented from adhering to the inner surface of the article 50 to be coated.

On the other hand, in the second embodiment, by making the outer diameter of the third rod-shaped portion 33 of the adsorption electrode 30 small so that the return adhesion occurs, the liquid is applied to the inner surface of the article 50 to be coated. ing.
In the second embodiment as well, liquid particles having a high penetration speed are adsorbed by the adsorption electrode 30 as in the first embodiment.

Then, the amount of returning and adhering liquid particles changes depending on how small the outer diameter of the third rod-shaped portion 33 of the adsorption electrode 30 is made.
Therefore, the amount of the liquid applied to the inner surface of the object 50 to be coated can be controlled by setting the outer diameter of the third rod-shaped portion 33 of the adsorption electrode 30 to what outer diameter.

Since the liquid is applied while rotating the article to be coated 50, the thickness of the coating film formed on the inner surface of the article to be coated 50 when viewed in the circumferential direction also becomes uniform. According to the electrostatic spraying method of the second embodiment, the thickness of the coating film formed on the inner surface is controlled to be a predetermined thickness, and a coating film having a uniform film thickness in the circumferential direction is formed. It is possible.

Although the electrostatic spraying device 10 of the present invention has been described above based on the specific embodiments, the present invention is not limited to the above specific embodiments, and appropriate modifications and improvements are made. What has been done is also included in the technical scope of the present invention, and it is obvious to those skilled in the art from the description of the claims.

DESCRIPTION OF SYMBOLS 10 Electrostatic spraying device 20 Liquid spraying part 21 Body part 21a Liquid supply port

21b Liquid channel

21c Hole part 21d Rear end opening 21e Female screw structure 22 Nozzle 22a Tip outer peripheral edge 22b Opening 23 Mandrel 23a Picking part 23b Electrical wiring connection Part 23c Male screw structure 23d Tip surface 24 Sealing member 30 Adsorption electrode 31 First bar-shaped part 31a Position regulating part 32 Second bar-shaped part 33 Third bar-shaped part 40 Voltage applying means 41 Voltage power supply 42 First electric wiring 43 Support part 43A 1 main body part 43a receiving part 43B first mounting part 43b screw hole 44 second electric wiring 45 holding part 45A second main body part 45a rotation holding part 45aa bearing part 45H1 first through hole 45ab fitting part 45ab1, 45ab2 end face 45ac first Holding body 45B Second mounting portion 45b Screw hole 45H2 Second through hole 46 Grounding means 47 Second holding body 47a Holding end portion 47b Stopping portion 47c Fourth through hole 50

Coated object

50a, 50b End portion 50H Through hole 60 Taylor cone

Claims

Electrostatic for applying liquid to an object to be coated, which has a cylindrical shape having a through hole in the length direction and has a plurality of holes penetrating from the outer surface to the inner surface defining the through hole on at least one side wall. A spraying method,
Disposing a conductive or semi-conductive adsorption electrode of an electrostatic spraying device in the through hole of the object to be coated,
While maintaining the same potential as the object to be coated and the adsorption electrode, a voltage is applied between the object to be coated and the liquid spraying section of the electrostatic spraying device and between the attraction electrode and the liquid spraying section, Generating an electrostatic force that sprays the liquid only by the electrostatic force from a nozzle of the liquid spraying unit by a voltage, and spraying the liquid toward the object to be coated.
The electrostatic spray according to claim 1, wherein, in the disposing step, the adsorption electrode is disposed in the through hole of the coating object so as not to contact the inner surface of the coating object. Method.
The article to be coated is a stent in which the at least one side wall is a mesh,
The electrostatic spraying method according to claim 1 or 2, wherein the liquid is a solvent in which a biodegradable and absorbable polymer that is decomposed and absorbed in a living body is dissolved.
4. In the step of spraying, the adsorption electrode forms a separation distance between the adsorption electrode and the inner surface where the liquid is not applied to the inner surface. The electrostatic spraying method described in.
Electrostatic for applying liquid to an object to be coated, which has a cylindrical shape having a through hole in the length direction and has a plurality of holes penetrating from the outer surface to the inner surface defining the through hole on at least one side wall. A spraying device,
The electrostatic spraying device,
A liquid spray section having a nozzle,
Located in the through-hole, a conductive or semi-conductive adsorption electrode,
While the potentials of the object to be coated and the adsorption electrode are the same, a voltage is applied between the object to be coated and the liquid spraying section and between the adsorption electrode and the liquid spraying section, and the voltage causes the nozzle to eject the liquid. An electrostatic spraying device comprising: a voltage applying unit that generates an electrostatic force that sprays the liquid only by the electrostatic force.
The said adsorption electrode is the size of the cross section of the part arrange|positioned in the said through-hole of the said to-be-coated object which does not contact the said through-hole of the to-be-coated object, The said 5 characterized by the above-mentioned. Electrostatic spraying device.
The electrostatic spraying device according to claim 5 or 6, wherein the adsorption electrode has a length longer than the length of the object to be coated.
In the adsorption electrode, a size of a cross section of a portion of the object to be coated, which is disposed in the through hole, forms a separation distance between the adsorption electrode and the inner surface for not applying the liquid to the inner surface. The electrostatic spraying device according to claim 5, wherein the electrostatic spraying device has a size.