JP5598659B2 - Corona discharge device and use thereof - Google Patents

Description

  The present invention relates to a corona discharge device, and more particularly to a corona discharge device capable of lowering the voltage applied to a discharge electrode.

  A continuous discharge caused by the generation of a non-uniform electric field around a pointed electrode (needle electrode) is generally referred to as corona discharge. Since this corona discharge can increase ions in the gas, it is applied to a dust collector or the like. Patent document 1 is mentioned as technical literature regarding a corona discharge generator. Patent Document 2 relates to an apparatus for producing ultrafine particles using corona discharge. Patent Documents 3 and 4 are cited as technical documents related to film formation using discharge.

JP 2007-35310 A Special table 2007-525321 gazette Special table 2008-519411 gazette Special table 2008-504442

  Usually, in order to generate a corona discharge by applying a DC voltage to an electrode under atmospheric pressure conditions, it is necessary to apply a high voltage to the electrode (discharge electrode). If the DC voltage applied to this electrode can be made lower, the applicability of corona discharge is further expanded, or it is meaningful because the usability is improved even in the field where corona discharge is conventionally used. An object of the present invention is to provide a technique capable of generating a corona discharge even with a lower applied voltage, and thus a corona discharge device to which the technique is applied.

  The present inventor has found that by applying a high-frequency electric field to the discharge electrode, the DC voltage at which corona discharge is generated from the electrode can be reduced, and the present invention has been completed based on such knowledge.

  The corona discharge device disclosed herein includes a discharge electrode having a tip having a shape capable of corona discharge. Moreover, it is connected to the said discharge electrode, The discharge voltage application means comprised so that a DC voltage could be applied to this electrode is provided. The discharge device further includes discharge assisting means that is not connected to the discharge electrode and configured to apply a high-frequency electric field to the electrode. Here, the discharge assisting unit includes a conductor disposed so as to surround a virtual line extending forward from the tip of the discharge electrode, and a high-frequency power source connected to the conductor.

  According to the apparatus having such a configuration, by applying a high-frequency electric field to the discharge electrode (typically, at least the tip of the electrode), a DC voltage applied to the discharge electrode (hereinafter also referred to as a discharge voltage) is further increased. Even if it is lowered, corona discharge can be generated from the tip of the electrode. Therefore, according to the corona discharge device, the lower limit value of the discharge voltage can be lowered as compared with the conventional corona discharge device that does not have the discharge assisting means.

  In one mode of the corona discharge device disclosed herein, the shape of the conductor is a ring shape or a coil shape. According to this aspect, the discharge voltage can be effectively reduced. Usually, an embodiment in which the conductor is disposed so that the virtual line passes through the approximate center of the ring or coil with respect to the discharge electrode can be preferably employed. This embodiment has an advantage that a more uniform corona discharge can be easily obtained.

  The corona discharge device disclosed herein can further include fluid supply means for supplying a fluid (a material exhibiting fluidity) to the tip of the discharge electrode. According to the apparatus having such a configuration, energy can be imparted to the fluid using the corona discharge generated from the tip. By this, for example, the fluid or its constituent components can be reacted (for example, crosslinking reaction, polymerization reaction, elimination reaction, etc.), or can be easily reacted (for example, excited state or activated state). .

  In a preferred embodiment of the corona discharge device provided with the fluid supply means, a fluid passage opening at the tip of the electrode is formed inside the discharge electrode. The fluid supply means is configured to supply fluid to the tip of the discharge electrode through the fluid passage. According to such a configuration, energy can be more efficiently applied to the fluid flowing out from the tip opening of the discharge electrode using the corona discharge.

  This specification also provides a method of manufacturing a coated article using any of the corona discharge devices disclosed herein. The method includes applying the DC voltage and the high frequency electric field to the discharge electrode to generate a corona discharge from the electrode. Moreover, it may include supplying a fluid containing a coating material used for forming the coating film to the tip of the discharge electrode. Moreover, it can include performing the process (corona discharge process) which makes the said coating-film raw material act the said corona discharge. Further, the method may include depositing the coating material subjected to the corona discharge treatment on a coating material (treatment target; hereinafter also referred to as a substrate) disposed at a position facing the tip of the discharge electrode. .

  According to such a method, by applying energy to the coating material using corona discharge, at least a part of the coating material is reacted (for example, crosslinking reaction, polymerization reaction, elimination reaction, etc.), or reaction It can be in a state (for example, an excited state or an activated state) that is easily performed. By this, the effect of at least one of the ability to form a coating film more efficiently and the formation of a highly functional coating film can be realized.

  The corona discharge treatment can be performed, for example, so as to accelerate the curing of the coating material. This eliminates or simplifies the operation of curing the coating film raw material in a separate process after the coating film raw material is deposited on the substrate.

  In a preferred aspect of the method disclosed herein, a discharge electrode having a fluid passage that opens at the tip of the electrode is used as the discharge electrode. And it further includes supplying the liquid containing the said coating-film raw material to the said front-end | tip from the said fluid channel | path, providing an electrostatic force, and making it mist. According to this aspect, at the tip of the discharge electrode, the liquid can be misted (electrospray) using electrostatic force, and corona discharge can be efficiently applied to the coating film material contained in the mist. By this, the effect of at least one of the ability to form a coating film more efficiently and the formation of a highly functional coating film can be realized.

  According to this specification, a coated article manufactured by any of the methods disclosed herein is further provided. For example, an article with a coating film in which various functions (for example, one or more functions among water repellency, antibacterial property, antifouling property, hardness improvement, etc.) are provided to the substrate by the coating film can be provided.

It is explanatory drawing which shows typically the corona discharge apparatus which concerns on one Embodiment. It is explanatory drawing which shows typically the corona discharge apparatus which concerns on one modification. It is a top view which expands and shows a part of FIG. It is sectional drawing which expands and shows the structure of a discharge electrode. It is a perspective view which shows the other structural example of a discharge assistance means. It is a perspective view which shows the further another structural example of a discharge assistance means.

  Hereinafter, preferred embodiments of the present invention will be described. Note that matters other than matters specifically mentioned in the present specification and necessary for the implementation of the present invention can be grasped as design matters of those skilled in the art based on the prior art in this field. The present invention can be carried out based on the contents disclosed in this specification and the drawings and common general technical knowledge in the field. In the following drawings, members / parts having the same action are described with the same reference numerals, and redundant descriptions may be omitted or simplified.

  One embodiment of the corona discharge device disclosed herein will be described with reference to FIG. The corona discharge device 1 includes a discharge electrode 10, a discharge voltage applying means 30 that applies a DC voltage to the electrode, and a discharge auxiliary means 50 that applies a high-frequency electric field. Further, fluid supply means 20 connected to the discharge electrode 10 may be provided. The corona discharge device can further include a chamber 2 that houses at least the tip 10A of the discharge electrode 10.

  The discharge electrode 10 only needs to have a tip 10A having a shape capable of corona discharge (pointed shape). For example, the discharge electrode 10 may have a rod shape (needle shape) that narrows toward the tip, a thin line shape, or the like. Can be used. Although it does not specifically limit, the material of the discharge electrode 10 can be copper, aluminum, stainless steel, tungsten, tantalum, etc., for example. Usually, the tip diameter of the discharge electrode 10 is suitably about 0.4 mm (injection needle gauge number 27G) to 1.2 mm (injection needle gauge number 18G), for example. In an experimental example to be described later, as the discharge electrode 10, a stainless steel electrode having a rod shape in which the vicinity of the tip is narrowed toward the tip and a tip diameter of 0.71 mm (injection needle gauge number 22G) was used.

  The internal structure of the discharge electrode 10 may be hollow or solid. When it is intended to supply a fluid to the tip 10A of the electrode 10 and perform corona discharge treatment (for example, when performing electrospray and corona discharge treatment at the tip 10A), for example, as shown in FIG. The discharge electrode 10 in which the fluid passage 12 opening to 10A is formed can be preferably used. In a preferred embodiment, fluid supply means 20 is connected to the fluid passage 12. In an experimental example to be described later, the discharge electrode 10 having a fluid passage 12 having a circular cross-sectional shape with a diameter of 0.41 μm (inner diameter of the injection needle gauge number 22G) formed therein was used.

  The fluid supplied to the tip of the discharge electrode 10 is not particularly limited as long as it is liquid or gaseous as a whole. The concept of “fluid that exhibits a liquid state or a gas state as a whole” includes not only a uniform liquid or gas, but also a liquid fluid containing solid fine particles in the liquid, a gaseous fluid containing fine droplets (mist), A gaseous fluid containing solid particulates may be included. Preferable examples of the fluid include various fluids (typically liquids) used for conventional electrospray deposition or electrospinning.

  The discharge voltage applying means 30 includes a DC power source 32 that can generate a DC high voltage. The DC power supply 32 is typically connected to the electrode 10 such that the discharge electrode 10 becomes a positive electrode (that is, a positive corona can be generated from the electrode 10). The discharge voltage application means 30 preferably has a performance capable of applying a DC voltage of, for example, at least about 3 kV or more (typically about 3.5 kV to 5 kV) to the discharge electrode 10.

  The corona discharge device 1 according to the present embodiment can be configured to include a grounded counter electrode (ground electrode) 70 at a position facing the tip A of the discharge electrode 10. An object to be processed (for example, a material to be coated) 72 by the corona discharge device 1 may be held on the surface of the ground electrode 70, or the object to be processed itself may be used as the ground electrode 70. As the ground electrode 70, it is possible to preferably employ an electrode in which at least the surface facing the tip A is formed in a substantially flat shape (typically, the entire shape is substantially a flat plate).

  The distance (gap) from the tip 10A of the discharge electrode 10 to the surface of the ground electrode 70 or the processing object 72 can be set to, for example, about 5 cm to 30 cm, and usually about 10 cm to 20 cm. According to the corona discharge device disclosed herein, the degree of freedom in setting the gap can be made higher than that of a conventional device that does not have the discharge assisting means. For example, since the direct-current voltage (discharge voltage) applied to the discharge electrode can be further reduced, even if the gap is narrowed, it is difficult for spark discharge to occur between the discharge electrode and the counter electrode. The ability to narrow the gap in this way is advantageous, for example, when high-precision processing is performed on a part of the processing object. In addition, the conventional corona discharge is generated by a high voltage applied between the discharge electrode (needle electrode) and the ground electrode opposite to the discharge electrode (needle electrode), whereas the current discharge is the tip of the electrode to which the high voltage is applied. Since a high frequency electric field is generated in the discharge, the gap can be widened, and the discharge can be performed even when the voltage between the opposing ground electrodes is equal to or lower than the voltage at which conventional corona discharge occurs. Therefore, the gap can be made wider than in the prior art. The wide gap as described above can efficiently process a wider range of processing objects that can be easily applied to processing objects having more various shapes (for example, shapes having irregularities on the surface). , Etc. are advantageous.

  As shown in FIG. 1, the imaginary line L obtained by extending the front end of the discharge electrode 10 forward is defined with respect to the surface of the ground electrode 70 (and hence the processing object 72). It is preferably set so as to be substantially vertical. This can prevent or suppress the bias of corona discharge.

  The discharge assisting means 50 is a component that is not directly connected to the discharge electrode 10, and includes a conductor 52 disposed so as to surround the virtual line L, and a high-frequency power source 56 connected to the conductor. Including. By operating the high-frequency power source 56, a high-frequency electric field can be generated around the conductor 52. As shown in FIG. 1, a matching box 58 may be interposed between the high frequency power source 56 and the conductor 52.

  The conductor 52 has a shape and an arrangement in which at least a part thereof forms a conductive path extending in the circumferential direction of the virtual line L. In a preferred embodiment, the single conductor 52 continuously provides 0.5 or more laps (more preferably 0.7 or more, more preferably 0.9 or more, typically around the imaginary line L, typically A conductive path extending approximately (one round or more) is formed. According to this form, the DC voltage (corona discharge voltage) applied to the discharge electrode 10 can be effectively reduced. In the example shown in FIG. 1, the coil-shaped conductor 52 forms a conductive path that continuously goes around the imaginary line L about two times. The coiled conductor 52 is wound in a conical shape in which the radius R increases as the distance from the discharge electrode 10 increases. However, the coiled conductor 52 is not limited to such a shape. For example, the conical shape in which the radius R decreases as the distance from the discharge electrode 10 increases. Or may be wound into a cylindrical shape having a constant radius R.

As a modification, there is a discharge assisting means 50 including a ring-shaped conductor 54 as shown in FIG. FIG. 3 is a plan view of the conductor 54 shown in FIG. 2 as viewed from the discharge electrode 10 side. Moreover, the shape of the conductor is not limited to a linear shape, and may be, for example, a conductor 154 having a perforated plate shape (typically a perforated disk shape) as shown in FIG. Further, as shown in FIG. 6, a conductor 254 (in the example shown in FIG. 6, a perforated disk-like mesh material) made of a mesh material may be used.
In the example shown in FIG. 1, the entire coiled conductor 52 is disposed between the tip 10A of the discharge electrode 10 and the ground electrode 70. For example, a part of the conductor 52 is more than the tip 10A. You may arrange | position above FIG. In other words, the tip 10 </ b> A of the discharge electrode 10 may enter the coiled conductor 52. It suffices that at least a part of the conductor 52 is disposed in front of the tip 10A (on the ground electrode 70 side). Furthermore, the corona discharge device disclosed herein can be preferably implemented typically with a single conductor, but also with a plurality of conductors that form mutually independent conductive paths. Can be implemented.

  In a preferred embodiment, the ring-shaped or coil-shaped conductor is arranged so that the virtual line L passes through the space surrounded by the ring or coil. Usually, it is preferable to arrange the ring or coil so that the center of the ring or the coil substantially coincides with the virtual line L. This can prevent or suppress the corona discharge bias (typically, the bias of the virtual line L with respect to the circumferential direction).

  The distance R from the imaginary line L to the conductor (in the case of a ring-shaped or coil-shaped conductor, R) is usually suitably about 2 cm to 10 cm, for example, about 3 cm to 5 cm. . In the experimental example to be described later, in the configuration shown in FIG. 1, a corona discharge device including a coiled conductor 52 having a radius R (average value) of 4 cm in the circumference closest to the tip 10 </ b> A was used. The coiled conductor 52 is wound twice in a conical shape, and has a radius R (average value) of 10 cm in the second round (the circumference on the side far from the tip 10A).

  The distance D from the tip 10A of the discharge electrode 10 to the conductor (in the case of a coiled conductor, the average value at the circumference closest to the tip 10A) is usually about 2 cm to 8 cm. For example, it can be about 3 cm to 5 cm. In an experimental example to be described later, a corona discharge device having a distance D (average value) of 5 cm in the configuration shown in FIG. 1 was used.

  As the high-frequency power source 56, a frequency capable of generating atmospheric pressure plasma (for example, about 1 kHz to 400 MHz) can be preferably used. Usually, an RF (Radio Frequency) power source of 13.56 MHz, 27 MHz or 40 MHz can be suitably used, and among these, 13.56 MHz is preferable. In an experimental example to be described later, an RF power source of 13.56 MHz was used.

  The power of the high frequency power supply when the corona discharge device is used is such that the effect of facilitating the corona discharge from the tip of the discharge electrode is exhibited (for example, the corona discharge is generated compared to the case where the high frequency power supply is not operated). The lower limit of the DC voltage to be obtained can be set appropriately). In a preferred embodiment, the power of the high frequency power source can be about 50W to 300W. This output range can be preferably employed when, for example, a DC voltage of 3.5 kV is applied to the discharge electrode in air at atmospheric pressure, and an RF power source with a frequency of 13.56 MHz is used as the high frequency power source.

  In one aspect of the corona discharge device disclosed herein, the DC voltage applied to the discharge electrode is 5 kV or less (typically 3.5 kV to 5 kV in air at atmospheric pressure with the high-frequency power source operated. ), Corona discharge can be generated stably from the tip of the electrode. In a preferred embodiment, the lower limit value of the DC voltage that can cause such corona discharge can be set to 1/2 or less (1/3 or less in a more preferred embodiment) as compared with the case where the discharge assisting means is not operated. In the case where the liquid is misted (electrospray) at the tip of the discharge electrode using this direct current voltage, the direct current voltage is approximately 2 kV or higher (typically 3 kV or higher, preferably 3.5 kV or higher, for example, (Approx. 3.5 kV to 5 kV) is appropriate.

The technique disclosed herein can be preferably used, for example, in a form in which corona discharge is generated under a pressure condition near atmospheric pressure, but the use form of the technique is not limited to this. For example, it can be applied to corona discharge under pressure conditions of about 1 × 10 ⁻² Pa to 1 × 10 ⁶ Pa (typically 0.1 × 10 ^{5 to} 5 × 10 ⁵ Pa). The discharge atmosphere may be in air or a gas atmosphere (inert gas, oxidizing gas, reducing gas, reactive gas, etc.) according to the purpose. In one aspect of the corona discharge device disclosed herein, the device comprises a chamber that houses at least the tip of the discharge electrode. According to this configuration, the pressure conditions during corona discharge, the atmospheric gas composition, and the like can be easily adjusted as necessary.

  The corona discharge device disclosed herein is used for modifying the surface of a processing object (for example, introducing a polar functional group into the surface), for use in decomposing and removing dirt on the surface of the processing object, and the processing object. For applications that form a coating film on the surface of the metal, for supplying ions into the discharge atmosphere (for example, to make it easier to ionize and collect dust in the atmosphere), and other various applications similar to conventional corona discharge devices It can be preferably used. The material of the object to be treated is not particularly limited, and may be various resins, paper, cloth, glass, ceramics, metal and the like.

  As an example of a preferable use, it can be grasped also as an application (a method of forming a coating film on the surface of an article, or a manufacturing method of a coating film) in which an article with a coating film is formed by forming a coating film on the surface of an object to be treated. ). For such use, for example, a discharge electrode 10 (see FIG. 3) in which a fluid passage 12 opening in the tip 10A is provided, and a fluid supply means 20 (see FIGS. 1 and 2) connected to the discharge electrode 10 The corona discharge device 1 having the above can be preferably used. When the fluid is a liquid, the fluid supply means 20 may include a tank for storing the liquid, a pump for sending the liquid to the fluid passage 12, a flow meter for detecting the supply speed, and the like as necessary. .

  Manufacture of the article with a coating film using the corona discharge apparatus 1 shown in FIG. 1 can be performed as follows, for example. That is, the corona discharge is generated from the tip 10 </ b> A of the electrode 10 by operating the high-frequency power supply 56 while applying a DC voltage from the DC power supply 32 to the discharge electrode 10 in atmospheric pressure air. While maintaining this corona discharge, a liquid obtained by dissolving a coating material (typically liquid) in an appropriate solvent is supplied from the fluid passage 12 to the tip 10A of the electrode 10 using the fluid supply means 20. And while making the said liquid mist using the DC voltage applied to the discharge electrode 10, discharge energy is provided to this mist. As a result, the solvent is volatilized from the liquid, and at least a part of the coating film raw material is reacted, or the reaction is made easy. The coating film raw material is deposited on the surface of the base material 72 disposed on the ground electrode 70 to form a coating film.

  In a preferred embodiment disclosed herein, the coating material that has been subjected to the corona discharge treatment is deposited on the surface of the substrate 72, so that the deposited coating material is subjected to a separate curing treatment (for example, discharge energy after deposition). The cured film is formed without the necessity of application of UV light, irradiation of ultraviolet rays, heating, or the like. That is, the corona discharge treatment can assist (promote) the curing of the coating material. However, even in such an embodiment, it is not particularly hindered to perform further curing treatment as necessary after depositing the coating material.

  Hereinafter, several examples related to the present invention will be described, but the present invention is not intended to be limited to the specific examples.

<Experimental example 1>
Using the corona discharge device 1 having the configuration shown in FIG. 1, an experiment was conducted to examine the effect of application of a high-frequency electric field on the corona discharge start voltage. This experiment was performed without arranging the workpiece 72 on the ground electrode 70 and without supplying the liquid to the fluid passage 12.

  That is, when a DC voltage of 3.5 kV was applied from the DC power source 32 to the discharge electrode 10 in air at atmospheric pressure, no corona discharge was observed at the tip 10A of the discharge electrode 10. Next, with the DC voltage (3.5 kV) applied, the high-frequency power source 56 (13.58 MHz RF power source) was turned on, and the power was gradually increased. As a result, it was recognized that corona discharge started at the tip 10A of the discharge electrode 10 when the power of the high-frequency power source 56 was increased to 60 W to 70 W (60 W in the first experiment and 68 W in the second experiment). . In other words, it was confirmed that corona discharge can be started at a discharge voltage of 3.5 kV by applying a high frequency electric field of 13.58 MHz and 60 W to 70 W.

  On the other hand, when the start of corona discharge was attempted by gradually increasing the DC voltage applied to the discharge electrode 10 with the high-frequency power source 56 turned off, it was confirmed that the corona discharge did not start until at least 10 kV. That is, by applying the high frequency electric field, the start voltage of corona discharge could be reduced to 1/2 or less (about 1/3).

<Experimental example 2>
Using the corona discharge device 1 having the configuration shown in FIG. 1, a coating film was formed on the surface of the substrate 72 held on the ground electrode 70 in air at atmospheric pressure. As the base material, a glass plate having a thickness of 0.8 mm (a slide glass manufactured by Matsunami Glass Industry, product name “White Edge Polish No. 1”) was used. The distance H from the tip A of the discharge electrode 10 to the surface of the glass plate (base material 72) was 23 cm. Hexamethyldisiloxane ((CH ₃ ) ₃ SiOSi (CH ₃ ) ₃ ; hereinafter sometimes referred to as “HMDSO”) was used as the coating material. This HMDSO is diluted with the same volume of ethanol containing 0.08 to 0.10% by mass of silver (Ag) fine particles having an average particle diameter of 100 nm (that is, the volume of HMDSO and the Ag particle-containing ethanol is 1: 1). The liquid having a viscosity suitable for electrospray (coating material solution) was prepared.

(Preparation of sample B1)
A DC voltage of 3.5 kV was applied to the discharge electrode 10, the power of the RF power source 56 (high frequency power supplied to the conductor 54) was set to 60 W, and corona discharge was generated from the tip 10 </ b> A of the discharge electrode 10. While continuing the corona discharge, the coating material solution was introduced into the fluid passage 12 at a supply rate of 4.2 × 10 ⁻³ mL / second using the fluid supply means 20. As a result, spraying of the coating material solution was continuously generated from the tip 10A of the discharge electrode 10 during corona discharge. The spray was deposited on the substrate 72 for 15 seconds. Thus, sample B1 (glass plate with a coating film) in which the coating film raw material that was electrosprayed and subjected to the corona discharge treatment was deposited on the glass plate was obtained. When the surface of this sample B1 was pressed with a finger, it was confirmed that the coating film material did not adhere to the finger or the coating film did not have a mark touched with the finger, and was a hard coating film. . It was 0.1 micrometer when the thickness of this coating film was measured by AFM method.

(Preparation of sample B2)
While the DC voltage of 3.5 kV is applied to the discharge electrode 10 and the RF power source 56 is turned off (therefore, no corona discharge is generated from the tip 10A), the above-mentioned coating material solution is 4.2 × 10 ^{− It} was introduced into the fluid passage 12 at a feed rate of ³ mL / sec. The coating material solution was sprayed at the tip 10A of the discharge electrode 10 and deposited on the substrate 72. After 15 seconds from the start of spraying, the supply of the coating material solution was stopped. Thus, sample B2 (glass plate with a coating film) in which the electrosprayed coating material (but not subjected to corona discharge treatment) was deposited on the glass plate was obtained. When the surface of this sample B2 was pressed with a finger, it was confirmed that the coating film was a highly viscous liquid (uncured or low cured).

  For the surfaces of Sample B1 and Sample B2 (the surface on which the coating material was deposited) and the surface of the untreated glass plate, the static contact angle of distilled water was measured using the droplet method (droplet diameter of about 25 ° C) in an atmosphere of 25 ° C. 2 mm). For this contact angle measurement, a contact angle measuring device (model “CA-X150”) manufactured by Kyowa Interface Science Co., Ltd. was used. As a result, the contact angle of sample B1 was 64 to 65 degrees, whereas in sample B2 and the untreated glass plate, the liquid droplets spread in a planar shape, and the contact angle could not be measured.

  In addition, except that the distance H from the tip A of the discharge electrode 10 to the surface of the glass plate was 15 cm, the coating material that was electrosprayed and corona discharged was deposited on the glass plate in the same manner as the sample B1. Sample B3 having the applied coating film was prepared. This coating film was cured in the same manner as Sample B1. Both the coating films of Samples B1 and B3 had high transparency. Moreover, it was confirmed by evaluation using a spectrocolorimeter that these coating films are almost colorless.

<Experimental example 3>
Similar to the preparation of Sample B1, except that paper (quality paper) was used as the substrate instead of the glass plate, and the distance H from the tip of the discharge electrode to the surface of the paper was 15 cm, except for the spray time. Was three levels of 5 seconds, 10 seconds, and 20 seconds, and three types of samples (coated paper) were obtained in which the coating material that was electrosprayed and treated with corona discharge was deposited on the surface of the paper. These samples are referred to as samples C1 (spray time 5 seconds), C2 (10 seconds), and C3 (20 seconds) in order from the shortest spray time. When the surfaces of Samples C1 to C3 were pressed with a finger, it was confirmed that a hard coating film was formed as in Sample B1. Moreover, when water droplets were attached to these coating films, it was confirmed that all showed good water repellency.

  The antibacterial effect of the coating film (water repellent film having Ag fine particles) according to the samples C1 to C3 was evaluated as follows. That is, about 3,000 cells of Escherichia coli were added to a culture solution (LB (Luria-Bertani) medium) in which the test pieces were immersed, and cultured at 37 ° C. for 24 hours. After culturing, the test piece was taken out and subjected to a first rinsing with 100 mL of phosphate buffered saline to remove E. coli that was weakly attached or laminated. The test piece after the first rinse was further rinsed with 10 mL of phosphate buffered saline, and could not be removed by the first rinse (Escherichia coli adhered firmly to the test piece) Removed. The multiplication density of the E. coli density on each test piece was compared by counting the bacterial density of the E. coli peeled from the test piece by the second rinse and making a relative comparison.

  As shown in Table 1, all of Samples C1 to C3 showed clear antibacterial properties compared to untreated paper. A higher antibacterial effect was obtained as the spray time increased.

  Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.

DESCRIPTION OF SYMBOLS 1 Corona discharge apparatus 2 Chamber 10 Discharge electrode 10A Tip 12 Fluid passage 20 Fluid supply means 30 Discharge voltage application means 32 DC power supply 50 Discharge auxiliary means 52 Coiled conductor (conductor)
54 Ring-shaped conductor (conductor)
56 High frequency power supply 58 Matching box

Claims (6)

A discharge electrode having a tip having a shape capable of corona discharge;
A discharge voltage applying means connected to the discharge electrode and configured to apply a DC voltage to the electrode;
Discharge auxiliary means configured so as to be disconnected from the discharge electrode and capable of applying a high-frequency electric field to the electrode;
A corona discharge device comprising:
Said discharge aid is seen containing a arranged conductors to surround an imaginary line extending forward from the tip of the discharge electrode, and a high frequency power source connected to said conductor,
Fluid supply means for supplying fluid to the tip of the discharge electrode;
A fluid passage opening at the tip of the electrode is formed inside the discharge electrode, and the fluid supply means is configured to supply fluid to the tip of the discharge electrode through the fluid passage. apparatus.   The apparatus according to claim 1, wherein the conductor is in a ring shape or a coil shape, and is arranged so that the virtual line passes through a space surrounded by the ring or coil. A method for producing an article with a coating film using the apparatus according to claim 1 or 2 ,
Applying the DC voltage and the high frequency electric field to the discharge electrode to cause a corona discharge from the electrode;
Supplying a fluid containing a coating material used for forming the coating film to the tip of the discharge electrode;
Applying a corona discharge treatment that causes the corona discharge to act on the coating material; and
Depositing the corona discharge treated coating material on a coating material disposed at a position facing the tip of the discharge electrode;
A method for producing an article with a coating film, comprising: The said corona discharge process is a method of Claim 3 performed so that hardening of the said coating-film raw material may be accelerated | stimulated. A liquid containing a pre Kinurimaku material supplied to the tip from the fluid passage, further encompass the mist by applying an electrostatic force, the method according to claim 3 or 4. An article with a coating film produced by the method according to any one of claims 3 to 5 .

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