JP6218111B2 - Film formation method for straight tube lamp - Google Patents

Description

  The present invention relates to a film forming method for a straight tube lamp in which a metal oxide film is formed on the outer surface of a straight tubular glass bulb.

  Conventionally, as a straight tube type lamp using a straight tubular glass bulb, an ultraviolet lamp mainly emitting ultraviolet rays and used in the field of sterilization or the like is known. This ultraviolet lamp has a problem that ozone is generated by ultraviolet rays having a short wavelength of 185 nm. Thus, an ultraviolet lamp has been proposed that can suppress the amount of ozone generated within a specified range while maintaining the bactericidal effect (see, for example, cited document 4). In this ultraviolet lamp, electrodes are provided inside both ends of a quartz glass bulb that transmits ultraviolet rays and encloses rare gas and mercury, and a zirconium oxide film having a predetermined thickness is formed on at least one of the inner and outer surfaces of the bulb. The light passing through the bulb absorbs 185 nm ultraviolet light that generates ozone without reducing the 254 nm ultraviolet light intensity necessary for sterilization and the like, and suppresses the ozone generation amount within a specified level.

  In the case of forming a metal oxide film such as this zirconium oxide film on the surface of the bulb, methods such as a vacuum deposition method, an ion plating method, and a vapor phase forming method (CVD) are conceivable. However, the immersion pulling method (dip coating method) is most advantageous in terms of ease of manufacture, mass productivity, ease of equipment, heat resistance, and the like. This immersion pulling method is a method in which a bulb is dipped in a metal compound solution and the solution is applied to the outer surface of the bulb by pulling it up. In this immersion pulling method, the bulb is immersed and the solution is applied to the outer surface of the bulb and then pulled and dried, and then fired to form a metal oxide film on the outer surface of the bulb. A method of forming an incandescent bulb using this immersion pulling method has been proposed (see, for example, cited document 1).

  A metal alkoxide or a metal chelate compound is used as a material substance of the metal oxide film in this immersion pulling method, and a highly volatile organic solvent such as ethanol or ethyl acetate is used as a solvent. The film thickness of the thin film formed on the valve surface is determined depending on the pulling speed of the valve from the solution. Generally, the larger the pulling speed, the thicker the film thickness. In addition, the relationship between the pulling angle of the valve with respect to the liquid level and the film thickness is also known, and when the pulling angle is not vertical, a method of ensuring the uniformity of the film thickness by adjusting the pulling speed is also known (for example, , Cited reference 3).

  By the way, when a metal oxide film is formed on the surface of the bulb by such an immersion pulling method, if the bulb is a straight tube mainly used for an ultraviolet lamp or the like, the bulb is placed on the liquid surface. It is usual practice to pull it up vertically (see, for example, FIG. 4 of cited document 2). When a straight tubular valve is pulled vertically to the liquid surface, if the length of the valve is at most about several tens of centimeters, the distance that the valve moves in the solution immersion and pulling process is within several tens of centimeters. It is said that the size of the entire coating apparatus does not need to be increased.

Japanese Unexamined Patent Publication No. 57-74963 JP 58-102458 A Japanese Patent Laid-Open No. 7-21997 JP 2006-92800 A

  However, some UV lamps have a total length exceeding 1 m. Therefore, when a metal oxide film is formed on the outer surface of a bulb of an ultraviolet lamp consisting of a straight tube having a total length of 1 m or more by the dip pulling method, if the bulb is pulled up from the liquid surface in the vertical direction. Then, the moving distance of the valve in the dipping and pulling process also reaches 1 m or more in the vertical direction, and it is necessary to secure a few meters in the vertical direction of the coating apparatus. For this reason, since the coating apparatus used for this immersion pulling method enlarges, it is not realistic. In addition, it takes a predetermined time for such a relatively long valve to be set vertically and pulled up over the entire length, resulting in a problem that production efficiency deteriorates.

  In order to solve such problems, the straight tube-like valve is supported in a posture that is slightly inclined from the horizontal or horizontal with respect to the liquid surface, and the solution is immersed and pulled up in that posture. If it carries out, the dimension of the vertical direction of a coating apparatus will also become small, and it will be thought that the time concerning the raising is also shortened.

  However, in the dip pulling method, it is inevitable that the liquid pool of the solution is generated at the lower end of the valve after the pulling from the solution. For this reason, when a bulb having a straight tube shape is immersed and pulled up in a posture that is slightly inclined from the horizontal or horizontal with respect to the liquid surface, a liquid reservoir is formed on the lower surface within the effective light emission range of the bulb, and the liquid reservoir The liquid film (the thin film of the solution before the entire film is solid-phased by firing, referred to herein as “liquid film”) is considerably thicker than the liquid film on the surface of the other part of the valve. Therefore, the metal oxide film formed by subsequent firing is still thicker than other metal oxide films, the binding force is reduced, the film does not become normal, and it is still easy to peel off. Issues that should remain were left.

  An object of the present invention is to form a metal oxide film having a predetermined film thickness on the outer surface of a valve having a long straight tube shape by adopting a dip pulling method, but the metal oxide formed on the outer surface of the valve It is an object of the present invention to provide a method for forming a straight tube lamp that does not cause separation of the film.

  In the present invention, a straight glass bulb provided with electrodes at both ends is immersed in a metal compound solution, the solution is applied to the outer surface of the bulb, and then pulled up, dried, and baked to form a metal on the outer surface of the bulb. This is an improvement of a method for forming a straight tube lamp for forming an oxide film.

Its distinctive point performs immersion and raising of the solution in a state of tilting the valve against horizontal performs liquid film homogenizing step to obtain a uniform solution film thickness adhering to the valve before after pulling is completely dried By the way.

Liquid film homogenizing step, the step of the lifted valve in a state inclined relative horizontal or step of rotating around the tube axis, the lifted valve in an inclined state against the horizontal in a vertical posture Both of these may be performed. And it is preferable that the inclination with respect to the horizontal of the valve | bulb in immersion and pulling is 10 degrees or less.

The straight tube lamp film deposition method of the present invention, since the immersion and raising of the solution in a state of tilting the valve against horizontal, even valve that forms a relatively long straight tube, the valve There is no increase in the distance traveled by the valve during dipping and lifting. For this reason, the dimension of the vertical direction of the coating apparatus used for the method of this invention can be made small, and the enlargement of the apparatus can be suppressed. And if the inclination with respect to the horizontal of the valve | bulb in immersion and pulling up is 10 degrees or less, the enlargement of an apparatus can be prevented reliably and the time concerning pulling up of a valve | bulb can also be shortened.

  Further, in the film forming method of the straight tube lamp of the present invention, a liquid film homogenizing step is performed for making the film thickness of the solution adhering to the bulb uniform after pulling and before completion of drying. It is possible to avoid the accumulation of the solution in the part. Then, the film thickness of the liquid film around the valve after the pulling is made uniform and then fired, and the metal oxide film formed thereby becomes a normal film having a uniform thickness, which is removed from the valve. It is possible to prevent a situation such as peeling. Therefore, the present invention provides a dip pulling method that does not cause peeling of the metal oxide film formed on the outer surface of the bulb.

  Here, if the liquid film homogenization step is a step of rotating the pulled up valve around the tube axis, the solution is prevented from flowing down by its own weight by constantly changing the lower end portion of the valve in the circumferential direction, Thereby, it is possible to prevent the liquid pool of the solution from being generated in a part of the circumferential direction (lower surface). In addition, if the liquid film homogenization step is a step in which the valve that has been pulled up is set to a vertical posture, the liquid pool of the solution is generated in a part of the circumferential direction by setting the flow direction of the coating solution to the axial direction. Can be prevented. And if both of these are performed, generation | occurrence | production of a liquid pool can be prevented reliably.

It is a figure which shows the film-forming method of embodiment of this invention. It is a figure which shows another liquid film equalization process. It is sectional drawing which shows the straight tube | pipe type ultraviolet lamp.

  Next, the best mode for carrying out the present invention will be described with reference to the drawings.

  FIG. 3 shows a straight tube type ultraviolet lamp 10 having a metal oxide film obtained by the method of the present invention. The ultraviolet lamp 10 includes a straight tube bulb 11 made of quartz glass and a pair of electrodes 12 and 22 disposed opposite to both ends of the bulb 11. The bulb 11 is formed into a cylindrical shape having an inner diameter of 20 mm with quartz glass having a high ultraviolet transmittance, and its effective light emission length is 250 mm. And it consists of a pair of electrodes 12 and 22 arrange | positioned at the both ends.

  The pair of electrodes 12 and 22 are welded to one ends of tungsten core rods 13 and 23 extending in opposite directions, and the other ends of the tungsten core rods 13 and 23 are further welded to one ends of the metal foils 14 and 24. The other ends of the metal foils 14 and 24 are electrically connected to one end of, for example, tungsten lead wires 16 and 26 using connection means such as caulking. From the tungsten core rods 13 and 23 excluding the electrodes 12 and 22 to one end of the lead wires 16 and 26, the end of the bulb 11 is heated and sealed. The metal foils 14 and 24 may be any material that has a thermal expansion coefficient close to that of the quartz glass that forms the bulb 11, but molybdenum is used as a material that satisfies this condition. The bulb 11 is filled with mercury and argon gas.

  Although not shown, a zirconium oxide film that transmits light of 254 nm and absorbs light of 185 nm is formed on the outer surface of the bulb 11. If the film thickness of the zirconium oxide film 13 is too thin, it transmits UV light of 185 nm, and if it is too thick, it causes absorption of 254 nm UV light and peeling of the film, so that it is formed to be 0.1 μm or more and 2.0 μm or less. To do. This zirconium oxide film is formed on the entire surface of the effective light emission length at least between the pair of electrodes 12 and 22 of the bulb 11. Thus, transmission of light having a wavelength of 185 nm is suppressed, and light having a wavelength of 254 nm is transmitted.

  The zirconium oxide film is formed by the film forming method of the present invention which is a so-called dip pulling method. That is, as shown in FIG. 1, a straight tubular glass bulb 11 having electrodes 12 and 22 inside both ends is immersed in a metal compound solution 21, and the solution 21 is applied to the outer surface of the bulb 11 and then pulled up. Then, it is fired to form a zirconium oxide film that is a metal oxide film on the outer surface of the bulb 11.

  Specifically, the film forming method of the present invention will be described. First, as shown in FIG. 1A, a metal compound solution 21 is prepared. In this embodiment, since a zirconium oxide film is formed, for example, a solution 21 containing several wt% of an organic zirconium compound is stored in the immersion tank 22 and prepared. Here, examples of the solvent include ethanol and ethyl acetate. In the tank 22 for storing the solution 21, a tank having a size capable of being immersed in a horizontal state with the straight tubular glass bulb 11 provided with the electrodes 12 and 22 inside the both ends is used.

  Next, the straight tubular glass bulb 11 provided with the electrodes 12 and 22 inside both ends is immersed in the solution 21 in a state of being inclined horizontally or horizontally. In this immersion, the valve 11 is preferably supported by the jig 23. FIG. 1 shows a jig 23 that supports both ends of the bulb 11 outside the electrodes 12 and 22. The jig 23 is composed of a pair of hooks 23a and 23b that support the end of the valve 11 at the lower end and a connecting piece 23c that connects the upper ends of the hooks 23a and 23b.

  And the valve | bulb 11 supported in the state inclined with respect to the horizontal or horizontal with such a jig | tool 23 descend | falls with the jig | tool 23 in that state, and is immersed in the solution 21. FIG. In FIG. 1, although the jig | tool 23 which supports the valve | bulb 11 in the state inclined 2 degree | times with respect to the horizontal is used, the inclination is not restricted to 2 degree | times. However, the inclination is preferably set to 10 degrees or less with respect to the horizontal.

  As shown in FIG. 1B, the solution 21 is applied to the outer surface of the valve 11 by immersing the valve 11 in the solution 21. Then, after the solution 21 is applied in this way, the valve 11 is pulled up and dried. Even when the valve 11 is pulled up, the valve 11 is horizontally or tilted with respect to the horizontal.

  Thus, in the straight tube type lamp film forming method of the present invention, since the bulb 11 is immersed or pulled up in the solution 21 in a state where the bulb 11 is inclined horizontally or horizontally, the bulb 11 having a relatively long straight tube shape. Even so, the moving distance of the valve 11 when the valve 11 is immersed and pulled up is small. For this reason, the dimension of the vertical direction of the coating apparatus used for the method of this invention can be made small, and the enlargement of the apparatus can be suppressed. Here, even if the valve 11 in the dipping and pulling is tilted, if the tilt with respect to the horizontal is 10 degrees or less, it is possible to reliably prevent the apparatus from becoming large, and to shorten the time for lifting the valve 11. It becomes possible.

  And the characteristic point in the method of the present invention is that the valve 11 is immersed in the solution 21 and pulled up in a state where the valve 11 is tilted horizontally or horizontally, and the valve 11 is put into the valve 11 before the completion of drying after the lifting. A liquid film homogenization step is performed to make the attached solution film thickness uniform.

  As a specific liquid film homogenization step, as shown in FIG. 1C, the valve 11 pulled up in a state of being inclined horizontally or horizontally can be rotated about the tube axis. This liquid film homogenization process must be performed before the drying of the solution 21 attached to the outer surface of the valve 11 is completed. The liquid film homogenization process for rotating the valve 11 is performed immediately after the valve 11 is lifted. It is preferable to start the rotation until the drying is completed.

  When the bulb 11 is rotated around the tube axis, it is preferable that the bulb 11 is disposed through both ends of the bulb 11 outside the electrodes 12 and 22, avoiding the range of the effective light emission length between the electrodes 12 and 22. And if the valve | bulb 11 pulled up from the solution 21 is rotated centering on a pipe axis before the drying, the lower end part of the valve | bulb 11 inclined from horizontal or horizontal will always change in the circumferential direction, It is possible to prevent the solution 21 from flowing down due to its own weight, thereby preventing the pool of the solution 21 from being generated in a part (lower surface) of the valve 11 in the circumferential direction. Therefore, by continuing the rotation until the drying is completed, a liquid film having a uniform thickness can be formed around the bulb 11.

  Further, if the overall length of the valve 11 is relatively short and there is room in the upper space of the immersion tank 22, the liquid film is uniformed as shown in FIG. The valve 11 pulled up may be in a vertical posture. If the pulled-up valve 11 is in a vertical posture, the direction in which the solution 21 adhering to the outer surface of the valve 11 flows down is the axial direction, so that the solution 21 gathers in a part in the circumferential direction of the valve 11 by its own weight. It is possible to prevent a situation in which accumulation occurs. And since it will wait for drying immediately after pulling up, it will become very easy compared with the case where rotation is continued until drying is completed.

  In addition, when a more uniform thickness of the solution 21 attached to the outer surface is required, the liquid film homogenizing step is performed with the valve 11 pulled up in a state of being inclined horizontally or horizontally about the tube axis. It may be a step of rotating to a vertical posture. In this case, it is preferable that the valve 11 after being pulled up is immediately brought into a vertical posture, and then the valve 11 is rotated until drying is completed. However, the valve 11 may be rotated to a vertical posture. Thus, it is considered that the occurrence of a liquid pool around the valve 11 can be surely prevented by performing both rotation and vertical posture.

  After the solution 21 adhering to the outer surface of the bulb 11 is dried, firing is performed to form a metal oxide film on the outer surface of the bulb 11. Since this firing is the same as the conventional immersion pulling method, a detailed description is omitted. And in the film-forming method of this invention, since a liquid film equalization process is performed before the baking, after forming the film thickness of the liquid film around the valve | bulb 11 after raising, it will bake, and it forms by it. The metal oxide film becomes a normal film having a uniform thickness and high binding force, and does not cause peeling of the metal oxide film starting from a thick part.

  Returning to FIG. 3, after the zirconium oxide film is formed around the bulb 11 in this manner, the coated lead wires 17 and 27 are connected to the other ends of the lead wires 16 and 26, and the connecting portion is made of ceramic. Covered by the caps 18 and 28. For this reason, the anode electrode 12 and the cathode electrode 22 are configured to be connectable to the lighting circuit through the coated lead wires 17 and 27 electrically connected inside the ceramic bases 18 and 28. In this way, the straight tubular ultraviolet lamp 10 is manufactured.

  In the above-described embodiment, the case where the straight tube lamp is an ultraviolet lamp in which a zirconium oxide film is formed around the bulb 11 has been described. However, the metal oxide film formed around the bulb 11 is not limited to the zirconium oxide film, and the oxide film material and the thickness thereof are appropriately changed depending on the use of the lamp and the required spectral transmittance characteristics. Shall.

  Further, the oxide film may be formed a plurality of times around the bulb 11 to be formed, and further, it may be configured as a multilayer film of two or more layers composed of a plurality of types of metal oxide films. In this case, it is possible to always form an oxide film without peeling by performing a liquid film homogenizing process every time an oxide film is generated.

  Next, examples of the present invention will be described together with comparative examples.

<Example 1>
As shown in FIG. 3, the glass bulb | ball 11 which comprised the straight tube shape shape | molded by the cylindrical shape with an internal diameter of 20 mm, and was equipped with the electrodes 12 and 22 inside both ends was prepared. The effective light emission length between the electrodes 12 and 22 of the bulb 11 was 250 mm. The pair of electrodes 12 and 22 are welded to one end of the metal foils 14 and 24 via tungsten core rods 13 and 23 extending in opposite directions, and the other ends of the metal foils 14 and 24 are connected to the lead wires 16 and 26 made of tungsten. The one end of each was electrically connected using a connecting means such as caulking. Then, from the tungsten core rods 13 and 23 to one end of the lead wires 16 and 26, the end portion of the bulb 11 was heated and sealed.

  On the other hand, as shown in FIG. 1A, a solution 21 containing several wt% of an organic zirconium compound was stored in a dipping tank 22 and prepared. Ethanol was used as the solvent, and adjustment was made so that drying was completed in about 30 seconds when applied to the surface of the bulb 11. In the tank 22 for storing the solution 21, a tube having a total length of 500 mm was used so that the straight tubular glass bulb 11 provided with the electrodes 12 and 22 at both ends was placed in a horizontal state and immersed. .

  Next, both ends of a straight tubular glass bulb 11 provided with electrodes 12 and 22 inside both ends are supported by hooks 23a and 23b of a jig 23, and the bulb 11 is inclined twice with respect to the horizontal. And supported by the jig 23. Then, the valve 11 was lowered together with the jig 23 in that state and immersed in the solution 21. As shown in FIG. 1B, the solution 21 is applied to the outer surface of the valve 11 by this immersion, and after 5 seconds, the valve 11 to which the solution 21 is applied at a rate of 2 mm per second is tilted by 2 degrees with respect to the horizontal. Pulled up while maintaining the state.

  As shown in FIG. 1 (c), the pulled-up valve 11 was rotated about the tube axis simultaneously with the pulling, and the rotation was continued for 30 seconds to complete the drying of the solution 21. The rotation speed was set to a rotation speed of about 20 rotations during the 30 seconds. The bulb 11 was rotated by the tester holding and rotating both ends of the bulb 11 outside the electrodes 12 and 22.

  After the drying of the solution 21 is completed, the bulb 11 is temporarily baked at 200 ° C. for 20 minutes and further baked at 1000 ° C. for 1 hour, and a zirconium oxide film as a metal oxide film is formed on the outer surface of the bulb 11. Formed. Ten such valves 11 were manufactured, and these ten valves 11 were taken as Example 1.

<Example 2>
Immediately after the valve 11 was pulled up, the valve 11 was set in a vertical posture as shown in FIG. Except for this, 10 valves 11 having a metal oxide film formed on the outer surface were obtained by the same material and the same procedure as in Example 1. These ten valves 11 were set as Example 2.

  In FIG. 2, the posture of the valve 11 is changed by the jig 23, but not limited to this, the valve 11 is removed from the jig 23 by hand immediately after being pulled up, and the posture of the valve 11 is made vertical by holding it by hand. Also good.

<Comparative Example 1>
After the valve 11 was lifted, the valve 11 was maintained in a state of being inclined twice with respect to the horizontal without rotating or moving until the solution 21 applied to the outer surface was completely dried. Except for this, 10 valves 11 having a metal oxide film formed on the outer surface were obtained by the same material and the same procedure as in Example 1. These ten valves 11 were used as Comparative Example 1.

<Comparative test and results>
The periphery of each of the ten bulbs 11 in Example 1 and Example 2 and the ten bulbs 11 in Comparative Example 1 in the range of each effective light emission length was visually observed using a 10 to 20 times magnifier. This observation was performed for the purpose of confirming whether or not the oxide film formed on the outer surface of the bulb 11 was peeled off and its range.

  As a result, in the bulb 11 of Comparative Example 1, the fact of peeling was confirmed in the oxide films formed on the outer surface of the bulb 11 in all ten, and the range was the full length of the effective light emission length in the longitudinal direction of the bulb 11. Confirmed in

  On the other hand, in the valve 11 of Example 1 and Example 2, in any case, the fact of peeling was not confirmed in the oxide film formed on the outer surface.

<Evaluation>
In Comparative Example 1, the fact that the oxide film was peeled was confirmed because the bulb 11 was immersed and pulled up in a posture that was slightly inclined from the horizontal or horizontal with respect to the liquid surface. It is considered that the metal oxide film formed by the formation of the reservoir and then firing was thicker than other metal oxide films, resulting in poor binding force, and did not become a normal film. .

  On the other hand, the fact that the oxide film was not peeled in Example 1 was confirmed because the pulled-up valve 11 was rotated around the tube axis, so that the lower end of the valve 11 always changed in the circumferential direction. This is probably because the liquid 21 did not accumulate in a part of the circumferential direction.

  Moreover, the fact that the oxide film was not peeled in Example 2 was not confirmed because the pulled-up valve 11 was immediately brought into a vertical posture, so that the flow direction of the metal compound solution 21 became the axial direction, and the circumferential direction This is probably because the liquid 21 did not accumulate in a part of the liquid.

10 UV lamp (straight tube lamp)
11 Valve 12, 22 Electrode 21 Metal compound solution

Claims (5)

A straight glass bulb (11) provided with electrodes (12, 22) inside both ends was immersed in a metal compound solution (21), and the solution (21) was applied to the outer surface of the bulb (11). In a method for forming a straight tube lamp, which is later pulled up and dried, and fired to form a metal oxide film on the outer surface of the bulb (11).
Perform immersion and raising of the the solution (21) wherein the valve (11) in a state tilted relative to horizontal,
A film forming method for a straight tube lamp, characterized in that a liquid film homogenizing step is performed for making the film thickness of the solution adhering to the bulb (11) uniform before completion of drying after pulling up. Liquid film homogenization film formation method of the straight-tube lamp according to claim 1, wherein the step of rotating the valve was pulled in an inclined state relative to the horizontal (11) around the tube axis. Liquid film homogenization is straight-tube lamp film forming method according to claim 1, wherein the step of the valve (11) lifted state to a vertical posture inclined with respect to horizontal. Formation of liquid film homogenizing step is a step to rotate and vertical posture lifted the valve (11) in the state around the tube axis inclined with respect to horizontal claim 1 straight-tube lamp according Method.   The film forming method for a straight tube lamp according to any one of claims 1 to 4, wherein the inclination of the bulb (11) with respect to the horizontal in dipping and pulling is 10 degrees or less.

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