JPS58103744A - Manufacturing method for fluorescent lamp - Google Patents

Abstract

PURPOSE:To obtain a fluorescent lamp without any ununiformities on a coated layer surface even when polyethylene oxide is used as a binder by spraying warm air with a specified range of temperature and air velocity from the top of a glass tube after coating process. CONSTITUTION:While a coated layer is being dried within at least 10% of the full length of a coated glass tube 6 from the top of the coated glass tube 6, the air sprayed on the coated glass tube 6 must have temperature (t) of 40 deg.C<=t <=80 deg.C and the warm air with its velocity (v) of 2m per second <=v<=15m per second is required to obtain an external view within the grade of a good product. Besides, to obtain the external view of the good product, the warm air of 50 deg.C<=t<=70 deg.C and of 4m per second <=v<= 14mper second is required. In this case, air velocity is measured by locating an anemothermometer at a position separated from a nozzle 5 approximately by 5mm.. This nozzle 5 is located at a position 5 to 15mm. from the top of the coated glass tube 6.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improvements in a method for manufacturing fluorescent lamps, and more particularly to the step of forming a phosphor layer on the inner surface of a glass tube in this method.

The coating method for the phosphor in a fluorescent lamp is to form a coating layer by pouring a coating liquid in which the phosphor is dispersed and suspended in a binder solution over the top of a glass tube vertically, and then applying a coating layer to the top of the tube. The coating layer is dried by blowing air. In general aqueous coating solutions for fluorescent lamps, carboxymethyl cellulose (CMC), hydroxyalkyl cellulose (hydroxyethyl cellulose, hydroxypropyl cellulose, etc.), methacrylic acid amo7, etc. are used as binders. Regarding the drying conditions for these aqueous coating liquids, the hot air temperature should preferably be as high as 90 C or more, and the wind speed should be as high as 10 m/s or more, from both the appearance of the coating layer and the shortening of the drying time.

However, in the case of an aqueous coating liquid using polyethylene oxide as a binder, under the above-mentioned drying conditions, unevenness occurs on the surface of the coating layer, resulting in poor appearance (9), so some kind of countermeasure is desired.

Therefore, an object of the present invention is to provide a method for manufacturing a fluorescent lamp that does not cause unevenness on the surface of the coating layer even when polyethylene oxide is used as a binder.

In order to achieve the above object, in the present invention, a coating liquid in which a phosphor is dispersed in an aqueous solution containing polyethylene oxide as a binder is poured above a glass tube held vertically, thereby forming a coating layer on the inner surface of the glass tube. After this coating process, the temperature is increased from the top of the glass tube to "C".
When the wind speed is Vm/sec, 40≦t≦80, and
A coating layer applied to the inner surface of a glass tube by blowing warm air in the range of 2≦V≦15 from the upper part of the glass tube until the coating layer in a range of at least 10% of the total length of the glass tube dries. The fluorescent lamp is manufactured by a manufacturing process comprising a drying step of drying the fluorescent lamp.

Due to the characteristic structural method of the present invention, even when a phosphor coating layer is formed using polyethylene oxide as an inder, there is almost no unevenness on the surface. As a result, it has become possible to reliably provide a fluorescent lamp with a good appearance.

Hereinafter, the present invention will be explained in detail with reference to Examples.

Prepare 170 m/ml of a 0°8% aqueous solution of polyethylene oxide with a molecular weight of 4 million or more, add 100 g of calcium halophosphate phosphor and 20 pI of a surfactant).
A coating liquid is prepared by adding m and suspending this. This coating liquid has a specific gravity of 1.37 when the liquid temperature is 25C.
The viscosity is 150 centipoise. A coating layer is formed on the inner surface of the glass tube by flowing this coating liquid upwardly onto the glass tube held vertically. After this coating process, as shown in Figure 1 (
The coating layer formed on the inner surface of the glass tube is dried using a dryer as shown in a) and (b). To be more specific, FIG. 1(a) shows the basic structure of the dryer, and FIG. 1(b) shows its side structure. The coating glass tube 6 sent from the above-mentioned coating process, which is the previous process, is transferred to an apparatus main body 7 that moves this glass tube 6.
It is held vertically by a tube chuck 8 protruding from the top.

The hot air for drying is generated by heating the air sent from the blower 1 to an optimum temperature using the heat exchanger 2. This hot air is passed through a blower duct 3, and its wind speed is adjusted by a damper 4. This hot air is then blown from the nozzle 5 into the coated glass tube 6. Note that 9 indicates the outer wall of the dryer, and 10 indicates an exhaust duct for humid air after drying.

Now, using the dryer described above, an experiment was conducted to dry the coated glass tube 6 by variously changing the hot air temperature tC1 and the wind speed v m 7 seconds, and to check whether the appearance was good or bad.

Here, "drying" is carried out by irradiating light onto the application tube 6 and adjusting the amount of transmitted light.In other words, in the undried state, the amount of transmitted light is small, but when it becomes dry, it decreases greatly. Note that the inner diameter of the coated glass tube 6 at this time is 2
7, the inner diameter of the nozzle 5 is 13 mm, and the coating glass tube 6
The total length of the temple is 600 temples. After the coating layer within 100wn from the top of the coated glass tube 6 has dried, t=9
07::, v = l Drying was performed with hot air at 6 m/sec. Further, the ambient temperature of the coated glass tube 6 during drying was 40 tZ'.

Table 1 shows the quality of the appearance of the coated glass tube 6, with ○ indicating a good product (with no uneven coating layer), △ indicating a good product (with some unevenness in the coating layer but no problem in actual use), and △ indicating a defective product (with no unevenness in the coating layer). The results are shown in which non-defective products (those with excessive coating layer unevenness and unsuitable for practical use) are indicated as x.

The following can be seen from Table 1. That is, at least 10% of the total length of the coated glass tube 6 from the top of the coated glass tube 6
Until the coating layer in the range dries, the air blown onto the coated glass tube 6 is warm air with a temperature t of 4 (1≦t≦SOC and a wind speed V i) of 12 m/sec≦V≦15 m/sec. is necessary to obtain an appearance within the acceptable limits. Furthermore, in order to obtain the appearance of a non-defective product, it is necessary that 50C≦t≦70tr and warm air of 4 m/sec≦V≦14 m/sec. Incidentally, the wind speed was measured by placing an anemometer (anemothermometer) at a position approximately 5 mm away from the nozzle 5.

This nozzle 5 is located 5 to 15 mm from the top of the coating glass tube 6.
It is located at

Further, as described above, the inner diameter of the nozzle 5 is the same as that of the coating glass tube 6.
It is desirable that the inner diameter of the tube is also smaller. Usually, the inner diameter of the coating glass tube 6 is in the range of 15mm to 38mm, so the nozzle 5
It is desirable that the inner diameter of the inner diameter is in the range of 10w to 30+++m. The dry air flow rate is 5 in the coated glass tube 6.
Although 0 to 150 t/min is desirable, when this value is converted to a wind speed at a position approximately 5 m away from the nozzle 5, it corresponds to 2 to 15 m/sec.

Now, if the temperature of the warm air is below 40C, even if you adjust the wind speed,
Further, even if the concentration of the coating liquid is increased, drying is slow and the coating liquid flows down, resulting in a thin coating layer on the upper part of the coated glass tube 6. As a result, when used as a fluorescent lamp, the internal electrodes become transparent, resulting in poor appearance. Additionally, if the temperature of the hot air exceeds 80C, the balance between the drying speed being too fast and the coating fluid rapidly warming up and the viscosity rapidly decreasing resulting in a faster flow rate will be lost even if the wind speed is adjusted. .

As a result, the coating layer may have uneven shading, pinholes, or unevenness due to partial repelling of the coating layer, resulting in poor appearance. Further, if the wind speed is less than 2 m/7 seconds, even if the temperature is adjusted, the coating layer on the upper part of the coated glass tube 6 will not be thin due to the same reason as when the air blowing temperature is too low, resulting in poor appearance. If the wind speed exceeds 15 m/s, the drying speed will be faster, but even if you adjust the temperature, the undried coating layer (the one that has dried slightly and is about to harden) will be forcibly moved. As a result, defects in the form of small vertical stripes occur, resulting in poor appearance. It should be noted that if the temperature around the coated glass tube 60 during drying is too high, there will be an adverse effect of accelerating the appearance defect phenomenon that occurs when the temperature of the hot air is too high. Therefore, it is desirable that the ambient temperature is 50C or less.

Now, in the drying method described above in which the coated glass tube 6 is held vertically and dried, the coated liquid flows down the inner surface of the coated glass tube 6 due to gravity, and hot air is blown upward from the coated glass tube 6. As the coating dries from the top of the glass tube 6,
Generally, the coating amount is thinner in the upper part of the coated glass tube 6, and tends to become thicker toward the lower part. The thickness of this coating layer can be adjusted by adjusting the concentration (specific gravity) of the coating liquid. Also, 10% from the top of the coated glass tube 6
After drying, in other words, if the coating liquid stops flowing down and the coating liquid no longer drips from the coating glass tube 6, even if the temperature of the hot air is increased to exceed 80C, the wind speed is
Even if the speed exceeds 5 m/sec, the appearance of the coated layer will not deteriorate, and in fact, by doing so, the drying time can be shortened. Furthermore, after the upper part of the coated glass tube 6 has dried by 930%, even if the undried part of the coated glass tube 6 is heated directly from the outside (using a gas burner, etc.), no defects will occur in the coated layer; By doing so, the drying time can be further shortened.

As described above, according to the present invention, even when a phosphor coating layer is formed using polyethylene oxide as a binder, unevenness does not occur on the surface thereof, and a fluorescent lamp with a good appearance can be reliably provided. It became so.

[Brief explanation of the drawing]

FIGS. 1(a) and 1(b) are a front view and a side view of a dryer for carrying out the method of manufacturing a fluorescent lamp according to the present invention. DESCRIPTION OF SYMBOLS 1... Prower 12... Heat exchanger, 3... Air duct, 4... Damper, 5... Nozzle, 6... Coated glass tube, 7... Dryer main body, 8 ...Pipe chuck, 9...Dryer outer wall, 10...Exhaust duct.

Claims (1)

[Claims] 1. A coating layer is formed on the inner surface of the glass tube by flowing a coating liquid in which a phosphor is dispersed in an aqueous solution containing polyethylene oxide as a binder above the glass tube held vertically. During the coating process and after the above coating process, the temperature at the top of the glass tube was set to 40°C when the wind speed was set to vm/sec.
By blowing hot air in the range of ≦t≦80 and 2≦V≦15 from the upper part of the glass tube until the coating layer in a range of at least 10% of the total length of the glass tube is dried. A method for manufacturing a fluorescent lamp, comprising a drying step of drying the coating layer applied to the inner surface of the glass tube. 2. The warm air blown onto the coating layer is 50≦t≦70
2. The method for producing a fluorescent rung according to item 1, wherein the hot air is in a range of 4≦V≦14. (1)