JP5029149B2 - Nitrocellulose solution, phosphor slurry and method for producing the same, phosphor film, and fluorescent lamp - Google Patents

Description

 The present invention relates to a nitrocellulose solution and a method for producing the same, a phosphor slurry and a method for producing the same, a phosphor coating, and a fluorescent lamp, and more specifically, a nitrocellulose solution capable of imparting an appropriate viscosity to the phosphor slurry and The present invention relates to a manufacturing method thereof, a phosphor slurry using the nitrocellulose solution, a manufacturing method thereof, a phosphor film formed using the phosphor slurry, and a fluorescent lamp provided with the phosphor film.

Conventionally, as a light source of a liquid crystal display (LCD) such as a liquid crystal monitor or a liquid crystal television, a cold cathode fluorescent discharge tube (cold cathode fluorescent lamp, CCFL) is used.
In this cold cathode fluorescent discharge tube, for example, a light emitting layer (phosphor film) made of a phosphor is formed on the inner surface of a translucent sealing tube in which both ends of a glass tube are sealed, and this translucent sealing is performed. Electrodes are provided on both ends of the tube, respectively, and an electron beam radioactive substance such as cesium oxide is attached to an arbitrary part in the translucent sealing tube, for example, an electrode. Further, mercury is contained in the translucent sealing tube. And a rare gas such as argon.
As a method of forming a phosphor film on the inner surface of the light-transmitting sealing tube, the glass tube forming the light-transmitting sealing tube is held vertically, and the lower end thereof is made into a slurry (phosphor slurry) containing the phosphor. A method of applying phosphor slurry to the inner surface of a glass tube by dipping and sucking it into the glass tube from its lower end is known.

  By the way, in recent years, it is necessary to make the cold cathode fluorescent discharge tube thinner and longer in accordance with the trend toward thinning and large screens of liquid crystal display devices. However, in the method of sucking up the phosphor slurry into the glass tube, the phosphor slurry is clogged in the glass tube, or the film thickness of the phosphor film formed in the glass tube becomes non-uniform. As a result, the cold cathode There has been a problem that variation in luminance and color difference of the fluorescent lamps of the type are increased.

In order to solve such a problem, the phosphor slurry is caused to flow from the upper end of the glass tube held vertically into the glass tube, and then a pressurized gas is introduced into the glass tube from the upper end of the glass tube. A method for forcibly discharging the clogged phosphor slurry is disclosed (for example, see Patent Document 1).
In addition, after applying phosphor slurry to the inner surface of the glass tube held vertically, air is blown to the lower end of the glass tube, and the air is allowed to flow at a high speed in the lateral direction at the lower end of the glass tube. Discloses a method of sucking the air in the glass tube and removing the phosphor slurry clogged at the lower end of the glass tube by the air flow sucked from the lower end (see, for example, Patent Document 2).

In addition, after applying the phosphor slurry to the inner surface of the glass tube, this glass tube is rotated with the central axis in the tube length direction as the rotation axis, thereby forming a phosphor film with a uniform film thickness on the inner surface of the glass tube. Is disclosed (see, for example, Patent Document 3).
Furthermore, a method for improving the uniformity of the phosphor film and the luminance of the fluorescent lamp by increasing the amount of nitrocellulose compounded as a viscosity imparting agent in the phosphor slurry is disclosed (for example, Patent Document 4). reference).
Japanese Patent Laid-Open No. 04-312741 Japanese Patent Laid-Open No. 06-349405 Japanese Patent No. 3381688 Japanese Patent No. 3336598

However, a method of forcibly discharging the phosphor slurry by injecting a pressurized gas into the glass tube, and removing the phosphor slurry clogged at the lower end by causing air to flow at a high speed in the lateral direction at the lower end of the glass tube. In the method and the method of rotating the glass tube to form a phosphor film having a uniform film thickness on the inner surface of the glass tube, it is necessary to modify the manufacturing apparatus or change the blending of the phosphor slurry. In addition, there was a problem that the manufacturing conditions had to be reviewed again.
In addition, by increasing the blending amount of nitrocellulose in the phosphor slurry to improve the uniformity of the phosphor coating and the brightness of the fluorescent lamp, increasing the blending amount of nitrocellulose increases the viscosity of the phosphor slurry. In addition, it is difficult not only to suck up the phosphor slurry into the glass tube, but the phosphor film formed by firing the phosphor slurry contains a large amount of residual organic substances, which reduces the luminance of the fluorescent lamp. There was a problem.

  The present invention has been made in view of the above circumstances, and can sufficiently adhere the phosphor slurry to the inner surface of the glass tube, and can provide a stable suspension state of the phosphor in the phosphor slurry. Nitrocellulose solution that can be maintained and method for producing the same, phosphor slurry using the nitrocellulose solution and method for producing the same, phosphor film formed using the phosphor slurry, and fluorescence provided with the phosphor film The purpose is to provide a lamp.

  As a result of intensive studies to solve the above problems, the present inventors prepared a nitrocellulose solution by sufficiently dissolving nitrocellulose in butyl acetate, and prepared a phosphor slurry using this nitrocellulose solution. Thus, it is possible to impart an appropriate viscosity to the phosphor slurry so that the phosphor slurry can sufficiently adhere to the inner surface of the glass tube, and in the phosphor slurry, the phosphor is stably suspended. Therefore, it was found that a phosphor film having a uniform film thickness can be formed using this phosphor slurry, and the present invention has been completed.

That is, nitrocellulose solutions of the present invention is a nitrocellulose solution used in the phosphor slurry containing a nitrocellulose solution and the phosphor contains a nitrocellulose, and butyl acetate, an average degree of polymerization of the nitrocellulose Is not less than 400 and not more than 2000, and the viscosity when the content of the nitrocellulose is 1% by weight is not less than 2 mPa · s and not more than 20 mPa · s.
It is good also as a nitrocellulose solution whose content rate of the said nitrocellulose is 1 to 2 weight%.

  The method for producing a nitrocellulose solution of the present invention is a method for producing a nitrocellulose solution containing nitrocellulose and butyl acetate, wherein the nitrocellulose and the butyl acetate are mixed to form a mixed solution, It is characterized by sonicating the solution.

  The phosphor slurry of the present invention contains nitrocellulose and butyl acetate, the average degree of polymerization of the nitrocellulose is 400 or more and 2000 or less, and the viscosity when the content of the nitrocellulose is 1% by weight is 2 mPa. A nitrocellulose solution having a concentration of s to 20 mPa · s and a phosphor is contained.

  The method for producing a phosphor slurry of the present invention is a method for producing a phosphor slurry containing a nitrocellulose solution containing nitrocellulose and butyl acetate and a phosphor, the nitrocellulose solution and The phosphors are mixed to form a mixture, and the mixture is subjected to ultrasonic treatment.

  The phosphor coating of the present invention comprises nitrocellulose and butyl acetate, the average degree of polymerization of the nitrocellulose is 400 or more and 2000 or less, and the viscosity when the content of the nitrocellulose is 1% by weight is 2 mPa. It is formed by using a phosphor slurry containing a nitrocellulose solution that is not less than s and not more than 20 mPa · s and a phosphor.

  The fluorescent lamp of the present invention contains nitrocellulose and butyl acetate, the average degree of polymerization of the nitrocellulose is 400 or more and 2000 or less, and the viscosity when the content of the nitrocellulose is 1% by weight is 2 mPa · a phosphor film formed by using a phosphor slurry containing a nitrocellulose solution of not less than s and not more than 20 mPa · s and a phosphor is provided inside the translucent sealing tube. Features.

According to the nitrocellulose solution of the present invention, a nitrocellulose solution used in a phosphor slurry containing a nitrocellulose solution and a phosphor, containing nitrocellulose and butyl acetate, the average degree of polymerization of the nitrocellulose Is not less than 400 and not more than 2000, and the viscosity when the content of the nitrocellulose is 1% by weight is not less than 2 mPa · s and not more than 20 mPa · s. Therefore, the nitrocellulose is sufficiently dissolved in butyl acetate. The viscosity of the phosphor slurry containing the nitrocellulose solution and the phosphor becomes moderate, and the phosphor slurry can be sufficiently adhered (coated) to the inner surface of the glass tube. Further, in this phosphor slurry, nitrocellulose can be sufficiently adsorbed to the phosphor, so that a stable suspended state of the phosphor can be maintained, and using this phosphor slurry, the film thickness is uniform. A phosphor coating can be formed.

  According to the method for producing a nitrocellulose solution of the present invention, the nitrocellulose and the butyl acetate are mixed to form a mixed solution, and the mixed solution is subjected to ultrasonic treatment. Since the viscosity of the cellulose solution is reduced, in the phosphor slurry formed by mixing this nitrocellulose solution and the phosphor, the nitrocellulose can be sufficiently adsorbed on the phosphor, and the phosphor is kept in a stable suspended state. be able to.

  According to the phosphor slurry of the present invention, it contains nitrocellulose and butyl acetate, the average degree of polymerization of the nitrocellulose is 400 or more and 2000 or less, and the viscosity when the content of the nitrocellulose is 1% by weight. Since it contains a nitrocellulose solution of 2 mPa · s or more and 20 mPa · s or less and a phosphor, it has an appropriate viscosity and can be sufficiently adhered (coated) to the inner surface of the glass tube. Further, since nitrocellulose is sufficiently adsorbed to the phosphor, a stable suspended state of the phosphor can be maintained, and a phosphor film having a uniform film thickness can be formed.

  According to the phosphor slurry manufacturing method of the present invention, the nitrocellulose solution and the phosphor are mixed to form a mixture, and the mixture is subjected to ultrasonic treatment, so that the nitrocellulose can be sufficiently adsorbed to the phosphor. , A stable suspended state of the phosphor can be maintained.

  According to the phosphor coating of the present invention, it contains nitrocellulose and butyl acetate, the average degree of polymerization of the nitrocellulose is 400 or more and 2000 or less, and the viscosity when the content of the nitrocellulose is 1% by weight. Is formed using a phosphor slurry containing a nitrocellulose solution of 2 mPa · s or more and 20 mPa · s or less and a phosphor, so that the film thickness becomes uniform and this phosphor film is provided. A fluorescent lamp can provide sufficient brightness.

  According to the fluorescent lamp of the present invention, it contains nitrocellulose and butyl acetate, the average polymerization degree of the nitrocellulose is 400 or more and 2000 or less, and the viscosity when the content of the nitrocellulose is 1% by weight is A phosphor film formed using a phosphor slurry containing a nitrocellulose solution of 2 mPa · s or more and 20 mPa · s or less and a phosphor is provided inside the translucent sealing tube. Therefore, since the phosphor film has a uniform film thickness, it has sufficient luminance as a fluorescent lamp.

The best mode of the nitrocellulose solution and the production method thereof, the phosphor slurry and the production method thereof, the phosphor coating and the fluorescent lamp of the present invention will be described.
This embodiment is specifically described for better understanding of the gist of the invention, and does not limit the present invention unless otherwise specified.

"Nitrocellulose solution"
The nitrocellulose solution of the present invention is a nitrocellulose solution containing nitrocellulose and butyl acetate, wherein the average polymerization degree of the nitrocellulose is 400 or more and 2000 or less, and the content of the nitrocellulose is 1 weight. %, The viscosity is 2 mPa · s or more and 20 mPa · s or less.

In the nitrocellulose solution of the present invention, the average degree of polymerization of nitrocellulose is 400 or more and 2000 or less, preferably 600 or more and 1000 or less.
The reason for setting the average degree of polymerization of nitrocellulose to 400 or more and 2000 or less is that when the average degree of polymerization of nitrocellulose is less than 400, the viscosity of the nitrocellulose solution is low, and sufficient viscosity cannot be imparted to the phosphor slurry. On the other hand, when the average degree of polymerization exceeds 2000, the fluidity of the phosphor slurry decreases due to the high viscosity of the nitrocellulose solution, and it is applied to the glass tube. This is because it becomes difficult.

In the nitrocellulose solution of the present invention, the content of nitrocellulose is 1% by weight or more and 2% by weight or less, preferably 1% by weight or more and 1.5% by weight.
When the content of nitrocellulose is less than 1% by weight, the phosphor slurry containing the nitrocellulose solution of the present invention and the phosphor cannot obtain a sufficient viscosity, and this phosphor slurry is sufficiently applied to the inner surface of the glass tube. Cannot adhere (apply). In addition, in this phosphor slurry, the nitrocellulose cannot be sufficiently adsorbed to the phosphor, and a stable suspension state of the phosphor cannot be maintained. A uniform phosphor film cannot be formed. On the other hand, when the content of nitrocellulose exceeds 2% by weight, the phosphor slurry containing the nitrocellulose solution of the present invention and the phosphor becomes too viscous and maintains a stable suspended state of the phosphor. Therefore, a phosphor film having a uniform film thickness cannot be formed using this phosphor slurry.

In the nitrocellulose solution of the present invention, the viscosity when the content of nitrocellulose is 1% by weight is 2 mPa · s or more and 20 mPa · s or less, preferably 10 mPa · s or more and 20 mPa · s or less.
The reason why the viscosity when the content of nitrocellulose is 1% by weight is 2 mPa · s or more and 20 mPa · s or less is that the viscosity when the content of nitrocellulose is 1% by weight is less than 2 mPa · s. This is because sufficient viscosity cannot be imparted to the slurry and the amount of phosphor attached to the glass tube becomes insufficient. On the other hand, when the viscosity when the content of nitrocellulose is 1% by weight exceeds 20 mPa · s, Since the phosphor slurry containing the nitrocellulose solution of the present invention and the phosphor cannot be kept in a stable state, the phosphor slurry containing the nitrocellulose solution of the present invention cannot be maintained in a stable state. This is because a phosphor film having a uniform film thickness cannot be formed.

 According to the nitrocellulose solution of the present invention, the average degree of polymerization of nitrocellulose is 400 or more and 2000 or less, and the viscosity when the content of nitrocellulose is 1% by weight is 2 mPa · s or more and 20 mPa · s or less. Since nitrocellulose is sufficiently dissolved in butyl acetate, the phosphor slurry containing the nitrocellulose solution and the phosphor of the present invention has an appropriate viscosity, and this phosphor slurry is sufficiently applied to the inner surface of the glass tube. Can be attached (coated). Further, in this phosphor slurry, nitrocellulose can be sufficiently adsorbed to the phosphor, so that a stable suspended state of the phosphor can be maintained, and using this phosphor slurry, the film thickness is uniform. A phosphor coating can be formed.

"Production method of nitrocellulose solution"
The method for producing a nitrocellulose solution of the present invention comprises mixing nitrocellulose and butyl acetate at a predetermined ratio, stirring and mixing to obtain a mixed solution, and sonicating the mixed solution to sufficiently add nitrocellulose to butyl acetate. A nitrocellulose solution having a viscosity of 2 mPa · s or more and 20 mPa · s or less when the content of nitrocellulose is 1% by weight is prepared.

 The ultrasonic treatment of the mixed solution of nitrocellulose and butyl acetate is preferably performed at a frequency of 20 kHz to 200 kHz for 10 seconds to 1000 seconds with respect to 100 g of nitrocellulose, and at a frequency of 20 kHz to 50 kHz for 30 seconds to 300 seconds. More preferably.

 The ultrasonic treatment of the mixed solution of nitrocellulose and butyl acetate is performed when nitrocellulose is dissolved in butyl acetate or immediately before the phosphor slurry is produced using the nitrocellulose solution of the present invention.

 According to the method for producing a nitrocellulose solution of the present invention, nitrocellulose and butyl acetate are mixed to form a mixed solution, and this mixed solution is subjected to ultrasonic treatment, so that nitrocellulose is sufficiently dissolved in butyl acetate, In the phosphor slurry containing the nitrocellulose solution and the phosphor, the viscosity when the nitrocellulose content is 1% by weight is 2 mPa · s or more and 20 mPa · s or less. Nitrocellulose can be sufficiently adsorbed to the phosphor, and a stable suspended state of the phosphor can be maintained. In addition, in the nitrocellulose solution, if the nitrocellulose is not sufficiently dissolved in acetic acid, the apparent molecular weight of the nitrocellulose increases due to the entanglement between the nitrocellulose molecules, and as a result, the viscosity of the nitrocellulose solution increases. . Then, in the phosphor slurry formed by blending this nitrocellulose solution and the phosphor, it becomes impossible to maintain a stable suspended state of the phosphor.

"Phosphor slurry"
The phosphor slurry of the present invention contains nitrocellulose and butyl acetate, the average degree of polymerization of the nitrocellulose is 400 or more and 2000 or less, and the viscosity when the content of the nitrocellulose is 1% by weight is 2 mPa. A slurry containing a nitrocellulose solution that is greater than or equal to s and less than or equal to 20 mPa · s and a phosphor.

 In the phosphor slurry of the present invention, the nitrocellulose solution of the present invention described above is used as the nitrocellulose solution.

Examples of the phosphor include red light emitting phosphors such as Y ₂ O ₃ : Eu, blue light emitting phosphors such as (SrCaBaMg) ₅ (PO ₄ ) ₃ Cl: Eu, and green light emitting materials such as LaPO ₄ : Ce and Tb. A mixture of phosphors is used.

In the phosphor slurry of the present invention, the content of the nitrocellulose solution is preferably 10% by weight or more and 90% by weight or less, more preferably 30% by weight or more and 50% by weight.
The reason why the content of the nitrocellulose solution is preferably 10% by weight or more and 90% by weight or less is that when the content of the nitrocellulose solution is less than 10% by weight, the phosphor slurry cannot obtain a sufficient viscosity. The phosphor slurry cannot be sufficiently adhered (applied) to the inner surface of the glass tube, and the phosphor slurry cannot sufficiently adsorb nitrocellulose to the phosphor slurry. This is because a turbid state cannot be maintained, so that there is a possibility that a phosphor film having a uniform film thickness cannot be formed using this phosphor slurry, while the content of the nitrocellulose solution is 90% by weight. Exceeding this value, the phosphor slurry becomes too viscous to maintain a stable suspended state of the phosphor. Te is because it may become impossible to form a uniform phosphor coating thickness.

In the phosphor slurry of the present invention, the phosphor content is preferably 10 wt% or more and 90 wt% or less, more preferably 30 wt% or more and 50 wt%.
The reason why the phosphor content is preferably 10% by weight or more and 90% by weight or less is that when the phosphor content is less than 10% by weight, it has a phosphor film formed using this phosphor slurry. This is because the fluorescent lamp does not provide sufficient luminance. On the other hand, when the phosphor content exceeds 90% by weight, the content of the nitrocellulose solution in the phosphor slurry is relatively reduced, and the phosphor is sufficiently charged. This is because it is impossible to impart a proper viscosity.

The phosphor slurry of the present invention may contain a binder, a solvent, a dispersant and the like depending on the application and specifications.
As the binder, a dispersion obtained by dispersing aluminum oxide (Al ₂ O ₃ ) particles in butyl acetate, a butyl acetate dispersion of low-melting glass particles, or the like is used.

The solvent is water and / or an organic solvent, but other organic polymers such as polymer monomers and oligomers alone or a mixture thereof are also preferably used.
Examples of the organic solvent include alcohols such as methanol, ethanol, 2-propanol, butanol, diacetone alcohol, furfuryl alcohol, ethylene glycol, and hexylene glycol; esters such as methyl acetate and ethyl acetate; diethyl ether , Ethers such as ethylene glycol monomethyl ether (methyl cellosolve), ethylene glycol monoethyl ether (ethyl cellosolve), ethylene glycol monobutyl ether (butyl cellosolve), diethylene glycol monomethyl ether, diethylene glycol monoethyl ether; acetone, methyl ethyl ketone, acetylacetone, acetoacetate Ketones such as: one or more of aromatic hydrocarbons such as toluene and xylene It can be used.

 According to the phosphor slurry of the present invention, it contains nitrocellulose and butyl acetate, the average degree of polymerization of nitrocellulose is 400 or more and 2000 or less, and the viscosity when the content of nitrocellulose is 1% by weight is 2 mPa. Since it contains a nitrocellulose solution of not less than s and not more than 20 mPa · s and a phosphor, the phosphor slurry of the present invention has an appropriate viscosity and is sufficiently adhered to the inner surface of the glass tube (coating) )can do. Further, since nitrocellulose is sufficiently adsorbed to the phosphor, a stable suspended state of the phosphor can be maintained, and a phosphor film having a uniform film thickness can be formed.

"Production method of phosphor slurry"
The method for producing a phosphor slurry of the present invention comprises mixing a nitrocellulose solution containing nitrocellulose and butyl acetate and a phosphor at a predetermined ratio, stirring and mixing to form a mixture, and ultrasonically mixing the mixture. By performing the treatment, the phosphor is sufficiently dispersed in the nitrocellulose solution, and the phosphor is sufficiently adsorbed to prepare a phosphor slurry.

 The ultrasonic treatment of a mixed solution of nitrocellulose and butyl acetate is preferably performed at a frequency of 20 kHz to 200 kHz for 10 seconds to 1000 seconds with respect to 100 g of nitrocellulose, and is performed at a frequency of 20 kHz to 50 kHz for 30 seconds to 300 seconds. It is more preferable.

 According to the method for producing a phosphor slurry of the present invention, a nitrocellulose solution and a phosphor are mixed to form a mixture, and this mixture is subjected to ultrasonic treatment, so that the nitrocellulose can be sufficiently adsorbed on the phosphor, A stable suspension of the body can be maintained.

"Phosphor coating"
The phosphor film of the present invention contains nitrocellulose and butyl acetate, the average degree of polymerization of nitrocellulose is 400 or more and 2000 or less, and the viscosity when the content of nitrocellulose is 1% by weight is 2 mPa · s. This is a film formed by using a phosphor slurry containing a nitrocellulose solution having a concentration of 20 mPa · s or less and a phosphor.

 In the phosphor film of the present invention, the phosphor slurry of the present invention described above is used as the phosphor slurry.

In order to produce the phosphor coating of the present invention, the phosphor slurry of the present invention is coated on a substrate to form a coating film, and then the coating film is dried or dried / heat treated in the air. .
As a base material, what is necessary is just a base material which can endure heat processing temperature, and a glass base material, a translucent ceramic base material, etc. are used suitably.
In particular, when this phosphor coating is applied to a fluorescent lamp, a glass tube that can meet the specifications of the fluorescent lamp is preferably used.

When applying the phosphor slurry, it is preferable to set the coating amount so that the film thickness of the phosphor coating film formed is 0.1 μm to 10 μm, particularly preferably 0.3 μm to 3 μm.
As a method for applying the phosphor slurry, since it can be used with a flat backlight, a spin coating method, a roll coating method, a spray coating method, a bar coating method, a dip coating method, a meniscus coating method, a suction coating method, a flow coating method, etc. A normal wet coating method can be used. In particular, when a phosphor film is formed on the inner surface of a glass tube like a fluorescent lamp, a suction coating method, a flow coating method, or the like is preferably used.

The drying temperature of the coating film may be a temperature at which the solvent contained in the phosphor slurry is sufficiently dissipated, for example, from room temperature to 150 ° C.
In this drying step, the coating film only needs to be sufficiently dried, may be dried only by heating, or may be blown with air. Specifically, hot air may be blown by air blow at normal temperature.
The heat treatment of the coating film is performed at a temperature in the range of 300 ° C. to 1000 ° C. for a predetermined time in a range where no defect occurs in the phosphor film.
Further, this heat treatment may be performed simultaneously with the protective film when the protective film and the phosphor film of the present invention are sequentially formed on the substrate.
In this way, the phosphor coating of the present invention is obtained.

  According to the phosphor coating of the present invention, nitrocellulose and butyl acetate are blended, the average degree of polymerization of nitrocellulose is 400 or more and 2000 or less, and the viscosity when the content of nitrocellulose is 1% by weight is 2 mPa. Since it is formed using a phosphor slurry containing a nitrocellulose solution that is not less than s and not more than 20 mPa · s and a phosphor, the film thickness is uniform, and the fluorescence provided with this phosphor film The lamp has sufficient brightness.

"Fluorescent lamp"
FIG. 1 shows an embodiment of the fluorescent lamp of the present invention, and is a schematic cross-sectional view along the longitudinal direction of the fluorescent lamp. FIG. 2 is a schematic cross-sectional view taken along line AA in FIG.

In the fluorescent lamp 10 of this embodiment, a phosphor coating 13 formed using the phosphor slurry of the present invention is provided inside a translucent sealing tube 11.
The translucent sealing tube 11 includes a glass tube 16 and sealing members 17 and 17 that seal both ends thereof.
The protective film 12 is formed on the entire inner wall (inner surface) of the translucent sealing tube 11 and has an electron emission function.

The phosphor film 13 is formed on the protective film 12.
The electrodes 14 are provided on both end sides in the translucent sealing tube 1, respectively.
The lead wire 15 is electrically connected to each electrode 14.
The sealed gas G is a gas sealed in the translucent sealing tube 1, and the sealed gas G is composed of a rare gas such as mercury or argon and an inert gas such as nitrogen.

  In this fluorescent lamp 10, the phosphor coating 13 formed using the phosphor slurry of the present invention is provided inside the translucent sealing tube 11, so that the phosphor coating 13 has a uniform film thickness. Therefore, it has sufficient luminance as a fluorescent lamp.

  In the fluorescent lamp 10 of this embodiment, a protective film 12 having an electron emission function is formed on the entire inner wall of the translucent sealing tube 11, and the phosphor film 13 is formed on the protective film 12 having the electron emission function. However, a three-layer structure in which a protective film 12 having an electron emission function is further formed on the phosphor coating 13 may be used, and the entire inner wall of the translucent sealing tube 11 is fluorescent. The body coating 13 may be formed, and the protective film 12 having an electron emission function may be formed on the phosphor coating 13.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited to a following example.

"Example 1"
(Preparation of nitrocellulose solution)
1 part by weight of nitrocellulose (average degree of polymerization: about 800, HI-2000, manufactured by Asahi Kasei Co., Ltd.) and 99 parts by weight of butyl acetate were blended and stirred for 24 hours to prepare a nitrocellulose solution.
100 g of this nitrocellulose solution was sonicated with an ultrasonic generator at 20 kHz for 30 seconds.

(Preparation of phosphor slurry)
35 parts by weight of a phosphor, 55 parts by weight of the above nitrocellulose solution, and 10 parts by weight of a binder were blended and stirred to prepare a phosphor slurry.
As phosphors, red light emitting phosphors: Y ₂ O ₃ : Eu, blue light emitting phosphors: (SrCaBaMg) ₅ (PO ₄ ) ₃ Cl: Eu, green light emitting phosphors: LaPO ₄ : Ce, Tb A mixture was used.
As the binder, a dispersion liquid (manufactured by Sumitomo Osaka Cement Co., Ltd.) obtained by dispersing 10 parts by weight of aluminum oxide (Al ₂ O ₃ ) particles in 90 parts by weight of butyl acetate was used.

(Preparation of glass tube with phosphor coating)
A straight tube glass having an inner diameter of 2 mm, an outer diameter of 4 mm, and a length of 100 mm is prepared. After immersing the lower end of the glass tube in the phosphor slurry, the phosphor slurry is sucked into the glass tube to form an inner surface of the glass tube. A phosphor slurry was applied.
Next, excess phosphor slurry was discharged out of the glass tube by its own weight, and then fired at 600 ° C. for 60 minutes in a firing furnace to obtain a glass tube with a phosphor coating.

"Example 2"
A glass tube with a phosphor coating was obtained in the same manner as in Example 1 except that the ultrasonic treatment time of the nitrocellulose solution by the ultrasonic generator was 45 seconds.

"Example 3"
A glass tube with a phosphor coating was obtained in the same manner as in Example 1 except that the ultrasonic treatment time of the nitrocellulose solution by the ultrasonic generator was set to 60 seconds.

Example 4
A glass tube with a phosphor coating was obtained in the same manner as in Example 1 except that the ultrasonic treatment time of the nitrocellulose solution by the ultrasonic generator was changed to 300 seconds.

“Comparative Example 1”
A glass tube with a phosphor coating was obtained in the same manner as in Example 1 except that the nitrocellulose solution was not subjected to ultrasonic treatment using an ultrasonic generator.

"Comparative Example 2"
A phosphor-coated glass tube was obtained in the same manner as in Example 1 except that the ultrasonic treatment time of the nitrocellulose solution by the ultrasonic generator was 2000 seconds.

[Evaluation]
For each of Examples 1 to 4 and Comparative Examples 1 and 2, the viscosity of the nitrocellulose solution and the uniformity of the film thickness of the phosphor film in the glass tube with the phosphor film were evaluated by the following methods.
(1) Viscosity of the nitrocellulose solution After measuring the kinematic viscosity of the nitrocellulose solution with an Ubbelohde viscometer and measuring the specific gravity of the nitrocellulose solution with a flotation method, The viscosity was calculated.

(2) Uniformity of phosphor coating film thickness Uniformity of the phosphor coating film thickness formed on the inner surface of the glass tube was visually confirmed.
These evaluation results are shown in Table 1.

According to these evaluation results, in Examples 1 to 4, since the viscosity of the nitrocellulose solution is within an appropriate range (2 mPa · s or more and 20 mPa · s or less), the fluorescence prepared using this nitrocellulose solution. Since the nitrocellulose was sufficiently adsorbed on the phosphor in the body slurry, it was found that the phosphor film formed by this phosphor slurry had a uniform film thickness.
On the other hand, in Comparative Example 1, since the viscosity of the nitrocellulose solution is 23 mPa · s, the phosphor slurry prepared using this nitrocellulose solution does not sufficiently adsorb nitrocellulose to the phosphor. It was found that the phosphor film formed from the slurry was not uniform in film thickness.
In Comparative Example 2, since the viscosity of the nitrocellulose solution is 1.5 mPa · s, the phosphor slurry prepared using this nitrocellulose solution does not sufficiently adsorb nitrocellulose to the phosphor. It was found that the phosphor film formed from the phosphor slurry was not uniform in film thickness.

1 is a schematic cross-sectional view showing a fluorescent lamp according to an embodiment of the present invention along a longitudinal direction of the fluorescent lamp. It is a schematic sectional drawing in alignment with the AA of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Fluorescent lamp 11 Translucent sealing tube 12 Protective film 13 having an electron emission function Phosphor layer 14 Electrode 15 Lead wire 16 Glass tube 17 Sealing member G Sealed gas

Claims (6)

A nitrocellulose solution used in a phosphor slurry containing a nitrocellulose solution and a phosphor,
It contains nitrocellulose and butyl acetate , the average degree of polymerization of the nitrocellulose is 400 or more and 2000 or less, and the viscosity when the content of the nitrocellulose is 1% by weight is 2 mPa · s or more and 20 mPa · s or less. A nitrocellulose solution characterized by being. The nitrocellulose solution according to claim 1, wherein the content of the nitrocellulose is 1% by weight or more and 2% by weight or less.   Containing nitrocellulose and butyl acetate, the average degree of polymerization of the nitrocellulose is 400 or more and 2000 or less, and the viscosity when the content of the nitrocellulose is 1% by weight is 2 mPa · s or more and 20 mPa · s or less. A phosphor slurry comprising a nitrocellulose solution and a phosphor. A method for producing a phosphor slurry comprising a nitrocellulose solution containing nitrocellulose and butyl acetate, and a phosphor,
A method for producing a phosphor slurry, comprising mixing the nitrocellulose solution and the phosphor to form a mixture, and subjecting the mixture to ultrasonic treatment.   Containing nitrocellulose and butyl acetate, the average degree of polymerization of the nitrocellulose is 400 or more and 2000 or less, and the viscosity when the content of the nitrocellulose is 1% by weight is 2 mPa · s or more and 20 mPa · s or less. A phosphor film formed by using a phosphor slurry containing a nitrocellulose solution and a phosphor.   Containing nitrocellulose and butyl acetate, the average degree of polymerization of the nitrocellulose is 400 or more and 2000 or less, and the viscosity when the content of the nitrocellulose is 1% by weight is 2 mPa · s or more and 20 mPa · s or less. A fluorescent lamp characterized in that a phosphor film formed using a phosphor slurry containing a nitrocellulose solution and a phosphor is provided on the inner surface of a translucent sealing tube.

Images