JP2005294049A - Fluorescent lamp manufacturing method and fluorescent lamp - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fluorescent lamp manufacturing method and a fluorescent lamp capable of improving the adhesion strength of a phosphor film without increasing the amount of a binder.
A fluorescent lamp manufacturing method including a manufacturing process of a phosphor suspension to be applied to an inner surface of a glass tube, wherein the manufacturing process of the phosphor suspension includes a phosphor powder and a thickener. A kneading step (S101) for mixing and kneading the contained solvent, and a stirring step (S102) for further adding and stirring a solvent containing a thickener and a binder after the kneading step.
[Selection] Figure 2

Description

  The present invention relates to a fluorescent lamp manufacturing method and a fluorescent lamp.

As a method of depositing a phosphor on the inner surface of a glass tube for a fluorescent lamp, a phosphor suspension is prepared by mixing and stirring phosphor powder and a solvent containing a binder and a thickener. Then, this suspension is applied to the inner surface of the glass tube, dried and fired (see, for example, Patent Document 1).
Japanese Patent Publication No.49-33871

However, in the above-described conventional phosphor suspension, aggregates are not sufficiently undissolved, and aggregates of phosphor particles are present in this liquid.
When such a fluorescent substance with aggregates is deposited on the inner surface of the glass tube, voids (voids) are generated between the contact portion between the fluorescent material and the inner surface of the glass tube and between the phosphor particles. For this reason, there exists a problem that the adhesion strength of a fluorescent substance film is not fully obtained.

If the deposition strength is low, the phosphor film may be peeled off due to vibrations received during the manufacturing process of the fluorescent lamp or during transportation of the finished product.
In recent years, mercury, which is a light-emitting substance of a fluorescent lamp, is sealed in the state of a compound impregnated with zinc or the like. Since this compound has a relatively high hardness, the phosphor film may be peeled off when it collides with the phosphor film formed on the inner surface of the glass tube. For this reason, it is required to further improve the deposition strength of the phosphor film.

In response to the above requirement, it is conceivable to increase the bonding strength by increasing the amount of the binder compared to the conventional case, thereby strengthening the bonding force between the phosphor particles or between the phosphor particles and the inner surface of the glass tube. However, since the binder usually blocks ultraviolet rays and visible light, an increase in the binder causes a decrease in the luminous flux of the fluorescent lamp.
The present invention has been made in view of the above problems, and the production of a fluorescent lamp capable of improving the adhesion strength of the phosphor film without increasing the amount of the binder as compared with the prior art. The object is to provide a method and a fluorescent lamp.

In order to achieve the above object, a method for manufacturing a fluorescent lamp according to the present invention is a method for manufacturing a fluorescent lamp including a step of manufacturing a phosphor suspension to be applied to the inner surface of a glass tube. The liquid manufacturing process includes mixing and kneading a phosphor powder and a solvent containing a thickener, and a kneading step;
After the kneading step, a stirring step of adding and stirring a solvent containing a thickener and a binder is further included.

The semi-solid body comprising the phosphor powder kneaded in the kneading step and the solvent containing a thickener has a viscosity in the range of 100 Pa · s to 10,000 Pa · s.
Further, the kneading step is performed using a kneader equipped with a kneading blade for performing planetary motion.

  The fluorescent lamp according to the present invention is manufactured by the above-described fluorescent lamp manufacturing method.

The method for producing a fluorescent lamp according to the present invention comprises a kneading step of mixing and kneading a phosphor suspension with a phosphor powder and a solvent containing a thickener, and a thickener after the kneading step. It is produced through a step of further adding a solvent containing a binder and stirring.
In the kneading step, the phosphor powder in the phosphor suspension can be pulverized and dispersed to primary particles, and the surface of the primary particles can be coated with a thickener. In the stirring step, the binder can be introduced between the phosphor particles dispersed to the primary particles without waste.

Thus, when the suspension is applied to a glass tube, the phosphor particles in the phosphor film can be densely arranged without gaps, and between the phosphor particles or between the inner surface of the glass tube and the phosphor particles. Bonding power can be increased.
Therefore, the deposition strength of the phosphor film can be improved without increasing the amount of the binder as compared with the conventional case.

Hereinafter, embodiments of the present invention will be described in detail.
1. Fluorescent Lamp FIG. 1 is a schematic view in which a fluorescent lamp (hereinafter simply referred to as “lamp”) 10 is partially cut away.
A lamp (FL20SS) 10 having a rated power of 20 W includes a straight glass tube 4 and a base 2 attached to both ends of the glass tube 4. The glass tube 4 has a tube outer diameter of 28 mm and a tube length of 580 mm. A predetermined amount of mercury and rare gas (not shown) are sealed in the glass tube 4. In addition, electrodes (not shown) are sealed at both ends of the glass tube 4, and the base 2 is attached so as to be electrically connected to the electrodes.

The phosphor film 6 is formed by applying a phosphor suspension to the inner surface of the glass tube 4 before the base 2 is attached, and then performing drying and firing processes.
2. Method for Producing Phosphor Suspension Hereinafter, a method for producing the phosphor suspension will be described in detail with reference to the drawings.
FIG. 2 is a process diagram illustrating a method for producing a phosphor suspension, and FIG. 3A is a schematic diagram illustrating a planetary mixer 20 used in a kneading step described later. The planetary mixer 20 as a kneading machine includes kneading blades 22a and 22b capable of planetary movement and small stirring blades 23a and 23b that rotate at high speed. Moreover, FIG.3 (b) is a figure which shows the semi-solid body 9 in the kneading tank 21 in the middle of the kneading | mixing process mentioned later.

(1) Kneading step The kneading step is a kneading process in which the phosphor powder and the solvent containing the thickener are mixed until the semi-solid 9 is obtained, and then the semi-solid 9 is kneaded and kneaded. Processing (summation processing).
First, in a kneading tank 21 of the planetary mixer 20, 10 kg of a three-wavelength region-emitting phosphor powder having a color temperature of 7200K and a predetermined amount of ethyl cellulose (hereinafter referred to as “EC”) as a thickener component are contained. A small amount (1.5 to 2.0 liters) of butyl acetate solvent is added.

Next, a kneading step (S101) for several tens of minutes is performed by rotating the kneading blades 22a and 22b. The rotation speed of the kneading blades 22a and 22b is set to 10 to 100 rpm for rotation and 5 to 50 rpm for revolution, for example.
In this kneading step, first, about 10 minutes after the start of rotation, the phosphor powder and the solvent are gradually mixed to form a semi-solid state 9 (mixing process). The semi-solid body 9 is kneaded (kneading process).

In this kneading process, the semi-solid body 9 having a relatively high viscosity is kneaded, so that the shearing force by the kneading blades 22a and 22b is effectively applied to the aggregates of the phosphor particles in the semi-solid body 9. The agglomerates can be unwound and dispersed to primary particles. At the same time, the thickening agent can be coated on the particle surfaces of the individual primary particles.
(2) Stirring step Subsequently, about 6.2 liters of a butyl acetate solution containing EC and a binder component (barium oxide, calcium oxide, boron oxide, calcium phosphate) are added to the kneading tank 21 containing the semi-solid 9. About 1.5 liters of butyl acetate solution containing several hundred grams, etc., and both the kneading blades 22a and 22b and the stirring blades 23a and 23b are rotated for about 10 minutes, thereby stirring processing (stirring step: S102) is performed.

As described above, since the phosphor particles in the phosphor suspension that has undergone the kneading step are dispersed to the primary particles, in this stirring treatment, the binder is effectively allowed to enter between the phosphor particles. be able to.
3. Adhesion strength of the phosphor film When the phosphor suspension prepared through the kneading step and the agitation step is applied to a glass tube and deposited, the deposition strength of the phosphor film can be increased as compared with the prior art.

This will be described in detail with reference to FIG. FIG. 4A is a schematic view showing the inner surface of the glass tube on which the phosphor suspension according to the present embodiment is applied and deposited, and FIG. 4B is an application of the phosphor suspension according to the prior art. -It is a schematic diagram which shows the inner surface of the deposited glass tube. In the figure, the phosphor particles are indicated by white circles.
Conventionally, since there are aggregates of phosphor particles in the phosphor suspension, as shown in FIG. 4B, even after this suspension is applied and deposited on the inner surface of the glass tube, There are voids 8a between the phosphor particles and voids 8b between the inner surface of the glass tube and the phosphor particles. For this reason, sufficient deposition strength of the phosphor film cannot be obtained.

  In addition, it seems that the said aggregate can be crushed, for example by making the stirring blade of a stirrer rotate at higher speed. However, according to the study by the present inventor, it was found that although the aggregates of the phosphor particles can be reduced by the high speed rotation, many phosphor particles are crushed and destroyed. When the phosphor particles are pulverized in this way, the conversion efficiency from ultraviolet rays to visible light is lowered.

  On the other hand, as described above, in the phosphor suspension of the present embodiment, the phosphor particles are crushed to primary particles, and the surface of each primary particle is coated with a thickener. Therefore, when applied to the inner surface of the glass tube, the bonding force between the phosphor particles and between the phosphor particles and the inner surface of the glass tube is higher than before. When the phosphor is applied to the inner surface of the glass tube by firing the glass tube coated with such a phosphor suspension, as shown in FIG. 4A, a conventional void 8a, 8b hardly exists, and the phosphor particles in the phosphor film can be densely arranged. Therefore, the deposition strength of the phosphor film can be increased as compared with the conventional case.

Moreover, in the phosphor film of the present embodiment, since there are almost no voids as in the prior art, ultraviolet rays can be efficiently converted into visible light, and luminous efficiency can be improved.
In addition, the phosphor film according to the present embodiment is more densely arranged by being pulverized / dispersed into primary particles than the conventional phosphor film, and the particles in the phosphor film are Since it is densely arranged, even if the amount of suspension applied is the same, it is about 10% thinner than the conventional film thickness (for example, 20 μm to 30 μm). Confirmed by electron micrographs.
4). Comparative Test Next, a test for comparing the characteristics of the phosphor suspension according to the present embodiment (the phosphor suspension of the example) and the conventional one was performed. In the phosphor suspension of the comparative example, 10 kg of phosphor powder and EC and a butyl acetate solution containing a binder component are put into a single-shaft stirrer, and the rotation speed of the stirring blades Was set at 1500 rpm and stirred for 30 minutes. The contents of EC and binder in the prepared phosphor suspension of the comparative example were adjusted to be the same as those in the example.

And both fluorescent substance suspensions were apply | coated to the inner surface of the glass tube 4 for lamp | ramp (FL20SS) 10 for rated power 20W, and it was made to adhere to the said inner surface through the known drying process and baking process.
Table 1 below shows the phosphor film coating of the lamp [Lamp (A)] coated with the phosphor suspension of the example and the lamp [Lamp (B)] coated with the phosphor suspension of the comparative example. It shows the results of measuring the wearing strength, the luminous flux, the presence or absence of voids, and the like.

(1) Phosphor film deposition strength A lamp filled with 10 mg of zinc impregnated with mercury was placed in a vibrator so that its tube axis substantially coincided with the horizontal direction, and this vibrator was accelerated at 1 G for 27 minutes. Vibrating in the vertical direction (frequency is about 5 to 50 Hz).

Then, when the presence or absence of peeling of the phosphor film from the inner surface of the glass tube was observed, it was judged that the film deposition strength was low because peeling of the phosphor film was observed in the lamp (b). On the other hand, in the lamp (A), since peeling of the phosphor film was hardly observed, it was judged that a higher film deposition strength than before was obtained.
(2) Luminous flux The comparison of the luminous flux of each of the five lamps (a) and lamp (b) showed that the average luminous flux in lamp (b) was 1395 (lm), whereas the lamp (b) ), The average luminous flux was 1410 (lm), an improvement of about 1%.

(3) Void In the lamp (b), since many voids of the phosphor particles were observed on the inner surface of the glass tube, the appearance of the glass tube was slightly inferior. On the other hand, in the lamp (A), almost no void was observed, so that a good appearance of the glass tube was obtained.
This void has also been observed in micrographs. 5A is an optical micrograph (magnification: 30 times) showing the inner surface of each glass tube 4 of the example, and FIG. 5B is a comparative example. In FIG. 5B, particularly conspicuous voids are surrounded by black circles.

As shown in FIG. 5, in the lamp with the phosphor of the comparative example, many voids exist. On the other hand, it can be seen that there are almost no voids in the lamps coated with the phosphors of the examples.
Each of the voids is fine, but when a large number of voids are present on the inner surface of the glass tube 4 as in the comparative example, the appearance of the glass tube is deteriorated.
5). Other Effects (1) Phosphor Application Amount FIG. 6 is a graph showing the relationship between the application amount per unit area of the phosphor inner surface of the phosphor and the luminous flux. The luminous flux is expressed as a relative value when the luminous flux when 3.3 (mg / cm ² ) phosphor is applied to the lamp (A) of the example is taken as 100%.

As shown in the figure, when the same amount of phosphor is applied, the luminous flux is higher in the lamp (A) of the example than in the lamp (B) of the comparative example. For this reason, if the same luminous flux as the conventional one is desired, the coating amount can be reduced, which is advantageous in terms of cost. For example, in the conventional lamp (b), since the coating amount is generally set to 3.0 (mg / cm ² ), if a similar luminous flux is desired, the lamp of the embodiment In (A), the coating amount can be reduced to 2.9 (mg / cm ² ).

(2) Tube end color difference Normally, a fluorescent lamp contains three types of phosphors corresponding to each of the red, blue, and green wavelength regions in the phosphor suspension. The wettability and the tendency of aggregation of the surface of each color phosphor are different. For this reason, when the phosphor suspension is applied in a state where the glass tube is erected, a phosphor having a high specific gravity or a phosphor that has low wettability and tends to aggregate is gathered under the glass tube, There is a color difference between both ends (tube end color difference).

In the present embodiment, the phosphor particles are dispersed up to the primary particles and the surface is covered with a thickener, so that the surface states are substantially the same. Therefore, the color difference at the end of the tube due to the difference in the wettability and the tendency of aggregation of the phosphors of the respective colors can be suppressed.
Table 2 is a table showing the results of measuring the tube end color difference between the E side (exhaust side) and the C side (sealing side) of the tube based on the CIE chromaticity coordinates. Note that the color differences ΔX and ΔY are multiplied by 10 ³ to make them easy to understand. In the examples and comparative examples, the phosphor suspensions were applied by flowing down (flushing) from the C-side ends of three 40 W straight tube lamp glass tubes. Is about 1.45 g.

As shown in the table, the average values (ave.) Of the tube end color differences of the three lamps in which the phosphors are applied to the examples are ΔX = 46 and ΔY = 86, which are significantly larger than those of the comparative example. It turns out that it is improving.
(3) Reduction of binder As described above, since the phosphor suspensions of the examples have a high bonding force between particles, the binder can efficiently enter between the particles in the firing step. For this reason, it becomes possible to reduce a binder compared with the past.

  The inventor reduced the amount of the binder (barium oxide, calcium oxide, boron oxide, calcium phosphate) added during the stirring process from 6% by weight of the lamp (ii) to 4% by weight ( C), the film deposition strength of the lamp (c) was similar to that of the lamp (b). Thus, even if the amount of the binder is slightly reduced, it is possible to obtain a film deposition strength with no practical problem.

As described above, four lamps (c) and lamps (a) with reduced binder were prepared and subjected to a lighting test. The average luminous flux maintenance factor after 1000 hours of lighting was determined to be that of lamp (c). Was 93.8%, and lamp (A) was 92.8%. As described above, in the lamp (c) in which the amount of the binder was reduced, the luminous flux maintenance factor was improved.
The reason for this is as follows. Originally, in the firing process, the low melting point glass (binder) must be melted after burning the thickener alone, but in actuality, the burning and melting of the thickener and the low melting point glass proceed simultaneously. However, both combine to produce an organic compound. The organic compound remaining in the phosphor film is gradually decomposed during lighting and generates an impure gas such as CO or CO ₂ in the discharge space, so that the luminous flux is gradually deteriorated.

That is, in the lamp (c), the amount of the binder is reduced compared to the lamp (a), so that the organic compound can be reduced, and the decrease in the luminous flux maintenance factor due to the presence of the organic compound can be suppressed. It was.
(4) Particle Size Distribution FIG. 7 is a graph showing the particle size distribution of the particle size of the particles measured by the laser scattering method. In the figure, the particle size is relatively represented with the magnitude of the peak value of the distribution of the comparative example being 100.

The particle diameter here is not the diameter of individual primary particles but the diameter of primary particles and aggregates of particles constituting the powder.
As shown in the figure, since the phosphor particles in the phosphor suspension of the example are mostly crushed into primary particles, the particle diameter is larger than that of the comparative example. For example, the particle size of the peak value of the distribution is about half.

(5) Viscosity of phosphor suspension Despite the same amount of phosphor powder and thickener in the phosphor suspension, the viscosity of the phosphor suspension of the produced example is 20 The viscosity of the phosphor suspension of the comparative example was 31.8 × 10 ⁻³ Pa · s, whereas it was 5 × 10 ⁻³ Pa · s. Was lower.

This is because, in the phosphor suspensions of the examples, the surface of each phosphor particle is sufficiently coated with the thickener, so the amount of the thickener floating in the liquid is the same as that of the comparative example. It is thought that it is because it is less compared to things.
Further, when the inner surface of the phosphor film in the phosphor suspension of the above example was observed with an electron micrograph, the outline of the phosphor particles of the example was clear. On the other hand, the outline of the comparative example was blurred. This is presumably because the phosphor particles were not sufficiently coated with the thickener, and the thickener was attached in a thin film on the surface of the phosphor film.
6). Others (1) Planetary Mixer In the kneading step of the above embodiment, the planetary mixer 20 is used as a kneading machine. Since the planetary mixer 20 has two kneading blades 22a and 22b that perform planetary motions of rotation and revolution, the kneading blades 22a and 22b and the aggregates of the phosphor particles or the aggregates collide with each other. Thus, a shearing force can be applied, and the agglomerates can be efficiently crushed to primary particles.

In addition to the kneading blades 22a and 22b, the planetary mixer 20 according to the present embodiment includes the stirring blades 23a and 23b, so that the mixing / kneading process and the stirring process are performed from the kneading tank 21 to a semi-solid body. This is very efficient because it can be carried out as it is without taking out materials such as 9 and solvent.
(2) Viscosity of the semi-solid 9 during the kneading process In the kneading process, in order to effectively apply a shearing force to the aggregates of the phosphor particles in the semi-solid 9, the semi-solid body during the kneading process. The viscosity of 9 is preferably in the range of 100 to 10000 Pa · s, and more preferably in the range of 400 to 1000 Pa · s.
7). Modifications (1) In the present embodiment, butyl acetate, which is an organic solvent, is used as a solvent containing a thickener component. However, the organic solvent is not limited to water, for example, water or alcohol. An organic solvent may be used.

  (2) In this embodiment, a three-wavelength light emitting phosphor for a color temperature of 7200K is used. However, even if a three-wavelength light emitting phosphor for a color temperature of 3200K or 5000K is used, the embodiment is used. It has been confirmed through experiments that the same effect as can be obtained.

  According to the fluorescent lamp manufacturing method of the present invention, it is possible to obtain a fluorescent lamp in which the deposition strength of the phosphor film is improved as compared with the related art.

It is the schematic which notched some fluorescent lamps. It is process drawing which shows the preparation methods of fluorescent substance suspension. (A) is a schematic diagram which shows the planetary mixer used in the case of a kneading | mixing step, (b) is a figure which shows the semi-solid body in the kneading tank in the middle of a kneading | mixing process. (A) is related with this Embodiment, (b) is a schematic diagram which shows the inner surface of the glass tube which apply | coated the phosphor suspension based on a prior art. (A) is an optical micrograph of the glass tube inner surface of an Example and (b) of a comparative example. It is a graph which shows the relationship between the coating amount per unit area of the glass tube inner surface of fluorescent substance, and emitted light flux. It is a graph which shows the particle size distribution of fluorescent substance particles.

Explanation of symbols

4 Glass tube 6 Phosphor 9 Semi-solid 10 Fluorescent lamp 20 Planetary mixer 22a, 22b Kneading blade

Claims (4)

A method of manufacturing a fluorescent lamp including a manufacturing process of a phosphor suspension applied to the inner surface of a glass tube,
The phosphor suspension manufacturing process includes:
A kneading step of mixing and kneading the phosphor powder and a solvent containing a thickener;
A method of manufacturing a fluorescent lamp, comprising: a stirring step of further adding and stirring a solvent containing a thickener and a binder after the kneading step.   The viscosity of a semi-solid body comprising the phosphor powder to be kneaded in the kneading step and the solvent containing a thickener is in the range of 100 Pa · s to 10,000 Pa · s. The manufacturing method of the fluorescent lamp as described in any one of.   The method of manufacturing a fluorescent lamp according to claim 1 or 2, wherein the kneading step is performed using a kneader equipped with a kneading blade that performs planetary motion.   A fluorescent lamp manufactured by the method for manufacturing a fluorescent lamp according to any one of claims 1 to 3.