JPH04179026A - Manufacture of shadow mask - Google Patents

Abstract

PURPOSE:To eliminate a process by which a compound consisting of bismuth, a Group IV element and oxygen is synthesized by a method wherein water glass or/further a Group IV element therewith are added to ultra-atomized bismuth oxide powder mixture and a solution of those substances is applied to the electron beam impact side of a shadow mask and after air-drying of the solution, baking process is applied thereto. CONSTITUTION:Water glass or further a compound consisting of Group IV element therewith are added to ultra-atomized bismuth oxide, powder and a mixture solution those substances is applied to the electron beam impact side of a shadow mask, and after air-drying of the solution, the paint film of the solution is baked. In the baking process, therefore, the bismuth oxide powder reacts directly on SiO2 in the component of water glass so that bismuth silicon oxide(BSO), etc., are produced. The process to synthesize a compound of heavy metal (Bi) like BSO, etc., a Group IV element and oxygen becomes, therefore, unnecessary, and also after the baking process of a shadow mask, a stable thermal deformation suppression film having a composition of mixture with a compound of Bi2O3 and BSO, etc., can be manufactured.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for manufacturing a shadow mask, and more particularly to a method for forming a thermal deformation suppressing film formed on a shadow mask to improve the brightness of a cathode ray tube. It is something.

[Conventional technology]

Conventionally, the formation of a thermal deformation suppressing film on the shadow mask of a cathode ray tube has been disclosed in Japanese Patent Publication No. 1445/1983 filed by the inventors.
9, JP-A-62-281240, JP-A-6
Publication No. 2-281241.

JP-A No. 62-283525, JP-A No. 62-283,
This is done as shown in Japanese Patent Application Laid-Open No. 63-213236, Kohan et al.

That is, first, bismuth oxide (B i20s ) powder,
Or Biass and bismuth silicon oxide (B
A predetermined amount of alkaline water glass and water are added to the mixed powder with i 123 j 020) and mixed to a predetermined viscosity. Next, this liquid mixture is applied by spraying onto the shadow mask, and then allowed to air dry.

Thereafter, the shadow mask was positioned and fixed on the face panel of the cathode ray tube, and then both were fired at a heating temperature of 450 IC 9 for a heating time of 30 minutes. As a result, a thermal deformation control film is formed on the shadow mask. Here, the above baking is generally called pair baking.

In addition, the above B 112310□. (hereinafter abbreviated as BSO), B l 12G e 020 (hereinafter abbreviated as BSO)
(abbreviated as BGO) or B 11□T iO2゜ (hereinafter referred to as BT
Heavy metals (Bi) such as
Alternatively, a compound of Ti) and oxygen may be used,
Exactly the same performance is obtained. In this case, a compound of germanium or titanium is used in addition to water glass.

Here, the above-mentioned same performance means that, firstly, during the operation of the cathode ray tube, which generates excited fluorescence by bombarding the phosphor picture elements of the screen for image reproduction with electron beams, it collides with the shadow mask. This performance suppresses to about 70% the occurrence of thermal distortion caused by the shadow mask's temperature rising to 40 to 80 degrees Celsius due to the kinetic energy of the electron beam, contributing to clear image reproduction without color shift.

Furthermore, secondly, during the synthesis of BSO etc., by generating it by heating, the CO generated when pulverizing Bi20z is
The purpose is to separate the two compounds.

That is, when BixOs is pulverized, at least the phenomenon expressed by equation (1) occurs.

Bi2O2+co2→BL 02 COs...(1)
In addition, B120 containing this B it 02 CO3,
In the heat treatment after water glass is mixed with the powder, the phenomenon shown by equation (2) occurs.

6 B is Os COs +S i 02→B11
2sio2゜+6CO□↑...(2) The separation of CO7 due to this phenomenon is not limited to BSO.
The above B replaces Si, Ge or Ti in SO.
The same can be said about OO and BTO.

[Invention or problem to be solved]

However, BSO and the like to be mixed with Bi20z require a step of synthesizing them before mixing, and the time and cost required for this step cannot be ignored.

For example, before mixing BSO with B12o3, B120a and SiO□ powder are weighed in advance at a molar ratio of 6:1, mixed well, and then baked in air at a temperature of about 800°C for 2 to 6 hours. After fully reacting and synthesizing, it is ground again to make a fine powder, and the mixing 9
Three steps were required: synthesis and pulverization.

This invention was made to solve the above-mentioned problems.
To eliminate the need for the process of synthesizing a compound of a group III element and oxygen, and to obtain a stable thermal deformation suppressing film having a mixture composition of Bt20s and a compound such as BSO, as in the conventional method, after firing the shadow mask. The purpose of this invention is to obtain a method for manufacturing a shadow mask that allows for the production of shadow masks.

[Means for Solving the Problems] A method for manufacturing a shadow mask according to the present invention includes a film forming step of forming a thermal deformation suppressing film on the electron beam impact side of the shadow mask by pulverizing bismuth oxide particles into ultrafine particles. a second step of adding water glass or the like to ultrafine bismuth oxide powder to form a mixture thereof; and applying the mixture to the electron beam impact side of the shadow mask. and a fourth step of baking the coating film of the liquid mixture to form the thermal deformation suppressing film.

[Effect]

In this invention, water glass or a compound of group Ⅰ elements is added to ultra-fine bismuth oxide powder, the mixed solution is applied to the electron beam impact side of the shadow mask, and after air drying, the coating film is baked. Since the treatment is performed, in the firing treatment, bismuth oxide powder directly reacts with 5in2 in the water glass component to generate bismuth silicon oxide (BSo) and the like. This eliminates the need for a step of synthesizing a compound of bismuth such as BSO, group Ⅰ element, and oxygen before mixing this with BjtOs.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

1 to 3 are diagrams for explaining a method of manufacturing a shadow mask according to an embodiment of the present invention.

In this example, the Bi20z powder is an ultrafine B12C powder with a particle size of 1 μm or less, preferably 0.2 μm to 0.7 μm.
This method differs from conventional shadow mask manufacturing methods only in that L powder is used.

The main processes of a method for manufacturing a shadow mask according to an embodiment of the present invention will be described below.

First, Bi2O, which is the main material used to suppress thermal strain and has a particle size of 5 to 10 μm, is ground to 1 to 0.5 μm using, for example, a wet grinder. For grinding, add 7 ml of water to the container.
．． Add 6kg of 2p, B120x, and add about 10c of 1% ammonia water to suppress the increase in viscosity during crushing.
Add c and stir to mix.

This mixed solution was mixed with zirconia 80 having a diameter of 0.5 mm.
% aqueous solution and containing a perforated rotating stirring plate at a rate of approximately 200 cc/min, the rotating stirring plate being rotated at 1300 PPM. Then the diameter is 1~0.
BizOs ultrafinely pulverized to about 5 μm is obtained (first step). The preferable diameter of the ultrafine BizOz is 0.2 μm to 0.7 μm.

Next, B12o was ultra-finely powdered in water without adding water glass.
Mix potash-based water glass and sodium-based water glass in the slurry-like liquid in Step 3 at a ratio of 9.1, and the concentration of 5iOz is 21.
．． Add 1500g of 5% water glass and add SiO2
129.2g of powder is added.

This S i 02 of 129.2g is determined based on the following calculation.

Weight of BizCL (6000g) ÷ Atomic weight of Bit○3 (465,96) = 12.88 mol 5iOz (32
2,5g)÷5iCL atomic weight (60,08)=5.3
7 moles 6 B 120w1 +s jot -B i 12S i 02G (""B50) Therefore, the amount of SiO2 required for 12.88 moles of BizOz to produce BSO is 2.15 (12°88 moles/6) moles. From 5.37-2゜15 (=3.22) mol, 3.22 mol of SiO2 contributes to the bonding between BizOi and the shadow mask, that is, as an adhesive, and 2.15
Since the mole does not directly contribute to the bonding with the shadow mask,
129.2 g of this 2.15 mole is the amount of SiO2 powder to be added.

This coating liquid containing S i O2 was placed in a container with a rotatable lid and stirred for about 1 hour to ensure uniform mixing (
second step).

This coating liquid is then sprayed to a thickness of about 2 mg/ad on the electron beam impact side of the shadow mask and allowed to air dry (Third Reference).

After that, this shadow mask is positioned and fixed on the face panel of the cathode ray tube, and then both are pair-baked at a heating temperature of 450°C and a heating time of 30 minutes (fourth step).
.

Next, the effects will be explained.

Conventionally, the BSO synthesis process involved 800
It requires heat treatment for several hours at around ℃, and conventional B
Among the SO production reactions, the inventors have revealed one BSO production reaction that goes through a decomposition reaction of Bi20zCO2 (hereinafter abbreviated as BOC). That is, the reaction is shown below.

6B 1202C(L +S 102-B i 12
s i 020+6 CO2 ↑ However, the B50ji produced through this reaction ultimately depends on the amount of BOC produced during the production process, and was only 10% of it.

On the other hand, when ultrafine Bi2O powder is used as in this example, the Bi2's powder reacts directly with 5ins in the water glass component under bare bake baking conditions of 450°C, producing BSO. will be generated. As a result, the 830 synthesis step, which requires a long processing time, can be eliminated, and since the amount of BSO produced depends on the ultrafine particle size of the B12o3 powder, Bi
By controlling the ultrafine particle size of 2's powder, BSO
The amount of production can be controlled arbitrarily.

In addition, since a shadow mask with a thermal deformation suppressing film as described above is incorporated into the color cathode ray tube, there is no thermal distortion, and the suction action of B12CL prevents C during operation inside the tube.
Floating of O□ can be suppressed.

The measurement results that are the basis for the direct reaction between the Bj20s powder and SiO2 will be shown below.

FIG. 1 shows the change in film composition before and after firing using an infrared absorption spectrum, with solid line A showing the spectrum before firing and dotted line B showing the spectrum after firing. In the figure, before firing, carbonates such as BOC are present near 1450 cm-'.
Water glass (S 102) near 105105O',
Absorption of Bi2O3 is clearly visible near 450 an-'. Furthermore, after firing, the formation of BSO appears at around 830 mark -1, and the absorption of BOC is considerably reduced. Until such changes, there is no big difference from the conventional one, but the film of this invention has a remarkable absorption of BSO. Specifically, the BSO production rate of this sample can be determined from the powder X-ray diffraction results described below. 30% or else the absorption peak of water glass is reduced to below 1000 an-' and B 120
．． It is remarkable that the absorption peak of It can be said that consumption (extinction) is clearly indicated.

That is, as a result of the consumption of the Si○2 component from the water glass, the bonding force in the water glass decreases, which appears as a decrease in the wave number of the 3102 absorption band.

On the other hand, the binding force of the B1-0 absorption band increases due to the solid solution of 5102, and therefore appears as an increase in the wave number of the absorption band.

Next, a method for determining the amount of BSO produced using powder X-ray diffraction method or infrared absorption method will be explained.

FIG. 2 shows the X-ray diffraction results of the BitO-/BSO mixed sample, where the horizontal axis is the X-ray diffraction angle and the vertical axis is the X-ray diffraction intensity. Among the X-ray diffraction intensity peaks ■ to ■ in the figure, peaks ■ and ■ are common to BltO2 and BSO, peaks ■ and ■ are for BSO alone, and peak ■ is for Bi,
O, it is a standalone item.

In the B501O, 0% sample, the peak ■ is the peak ■
(37mm), so the height of peak ■ based on B30 minutes is 37m.
mX4.14=153mm, and Mari B i, O,
In the 0% lO sample, Bi2° and min are 184 mm from the highest peak (2), so the amount of BSO produced can be obtained as follows.

BitOs=184/(184+153)=0.5
5 BSO=153/(184+153) =0.45 On the other hand, in the infrared absorption method, the absorbance of the characteristic absorption band (832 cm-') of BSO after firing and the characteristic absorption band (470 cm-') of (Bi20,)' The absorbance of BSO is determined by the baseline method, and the relative absorbance of BSO is determined based on the absorbance of Bi2O3 before firing.

Figure 3 is a log-log plot diagram showing the relationship between the BSO production amount determined from X-ray diffraction and the BSO relative absorbance determined from infrared absorption. I understand that.

As described above, in this invention, ultrafine Bi2O3 directly reacts with 5iOz in water glass to generate BSO, so 3102 in water glass is consumed, and ultimately the intended composition of water glass is The (SiO2/alkali metal) ratio varies depending on BSO formation. Changes in water glass composition increase the amount of outgassing, which in turn affects the life characteristics of the CRT, so if the amount of BS○ produced is large, the consumption
It is desirable to compensate for 102 minutes.

Now, assuming that the amount of BSO produced is 5゜wt% of the raw material bismuth oxide, and calculating the amount of S s O2 consumed, it is 6k.
Since 3 kg of Bt20z out of g of BizOz is converted to BSO, the required number of moles of 5i02 is calculated from the following formula: 6E3i20s +5iOz→B 1 +zS j 0
2°Bit'2 6.438 (=3000/465.9
6) Since it is 6.438/6 mole for mole, 5iO
The amount of z is 64°38 (= 60 x (6,438/
6)) g.

Therefore, if the amount of BS○ produced is calculated proportionally, the required amount of SiOx will be as shown in the table below.

In this table, BizOz is 6 kg.

Normally, the amount of BSO produced is between 20 and 80 wt%, so
The amount of 5int consumed is between 26 and 103g. Therefore, add S to compensate for the consumed 5i02 minutes.
io 2 minutes is also between 26 and 103g. S to be added
In addition to Sin and powder, iO2 can be added in the form of water glass that does not contain alkali metals, such as Ludox (manufactured by DuPont), and the amount to be added may be determined based on the solid content.

Table Amount of BSO generated and required amount of SiO2 [Effects of the invention] As described above, according to the method for producing a shadow mask according to the present invention, water glass or a compound of a group (III) element is added to ultrafine bismuth oxide powder. The mixed solution was applied to the electron beam impact side of the shadow mask, and after air drying, the coating film was baked.
Directly reacts with O2 to form bismuth silicon oxide (BS
O) etc. will be generated. As a result, a compound of bismuth, group Ⅰ element, and oxygen such as BSO can be mixed with B12.
There is no need for a step of synthesis before mixing with o3, and a shadow mask having a highly stable thermal deformation suppressing film can be manufactured using the same production process as the conventional method.

[Brief explanation of drawings]

FIG. 1 is an infrared absorption spectrum diagram of a thermal deformation suppressing film in a method for manufacturing a shadow mask according to an embodiment of the present invention;
FIG. 2 shows the amount of Bi used in the thermal deformation suppressing film. /BSO
Figure 3 shows the X-ray diffraction pattern for the mixed sample.
Based on the BSO production amount based on the linear diffraction method and the infrared absorption method <B
It is a figure showing the relationship with relative absorbance of SO. In the figure, A is the infrared spectrum before firing, B is the infrared spectrum after firing, ■, ■ are B i20, and BSO
Diffraction intensity peak common to ■. (2) is the peak of the diffraction intensity of BS○ alone, and (2) is the peak of the diffraction intensity of Bi2O alone. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (4)

[Claims] (1) A method for manufacturing a shadow mask, which includes a film forming step of forming a thermal deformation suppressing film having a mixture composition of a heavy metal oxide and a compound of the heavy metal, group IV element, and oxygen on the electron beam impact side of the shadow mask. In this case, the above-mentioned film forming step includes a first step of pulverizing the heavy metal oxide particles into ultra-fine particles, and a first step of adding water glass to the ultra-fine-grained heavy metal oxide powder to create a mixed solution thereof. a third step of applying the mixed solution to the electron beam impact side of the shadow mask and drying it naturally; and a third step of baking the coated film of the mixed solution to form the thermal deformation suppressing film. 4. A method for manufacturing a shadow mask, comprising the steps of step 4. (2) The method of manufacturing a shadow mask according to claim 1, wherein the heavy metal oxide is bismuth oxide, and the ultrafine particles of the oxide have a diameter of 0.2 to 1 μm. (3) The above water glass is silicon oxide powder corresponding to 0.3 to 1.7 weight % of the heavy metal oxide, or equivalent to 0.3 to 1.7 weight % of the heavy metal oxide as a solid content. 2. The method for producing a shadow mask according to claim 1, wherein the shadow mask is made of neutral water glass containing silicon oxide. (4) The method for manufacturing a shadow mask according to claim 1, wherein the water glass is alkaline water glass made of sodium water glass or a mixed water glass of sodium water glass and potassium water glass.