JP2000317247A - Gas absorption getter and method for producing the same - Google Patents

Abstract

(57) [Abstract] [Problem] A getter which is easy to be formed into various shapes and dimensions, and does not peel off or release alloy during handling up to assembling into equipment and during use in equipment. And a method for producing the same. A gas absorbing alloy powder is housed in the case and molded integrally with the case. The gas absorbing alloy is supplied to the outside air through an opening of the case, for example, a slit and a through hole. A gas-absorbing getter, which is capable of contacting with a getter. The getter can be easily manufactured by forming a thin metal plate into a cylindrical shape, filling the inside with a gas absorbing alloy powder, and rolling, drawing, pressing or cutting, or two or more of these steps.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to a container or device (hereinafter referred to as a closed device) whose inside is kept in a vacuum or an inert gas atmosphere, such as a thermos, a plasma display panel and the like. The present invention relates to a getter for absorbing air or impurity gas therein and a method for manufacturing the getter.

[0002]

2. Description of the Related Art A sealed device as described above is manufactured by evacuating the inside of the device with a vacuum pump and sealing it during production, or by filling an inert gas after evacuating the device. A gas absorbent (getter) is often sealed inside the device in order to prevent a reduction in the degree of vacuum during use or to absorb an impurity gas in an inert gas. Further, depending on the type of device and the manufacturing method, a desired degree of vacuum may be obtained only with a getter without using a vacuum pump.

[0003] For example, in a plasma display panel, an inert gas such as neon or xenon is sealed after evacuation, but oxygen, nitrogen, water vapor mixed in the gas, or methane generated inevitably in a panel manufacturing process. A getter is used for the purpose of absorbing and removing hydrocarbon gas such as. Since the impurity gas as described above has an adverse effect on the plasma generation intensity and stability when using the panel,
Its removal is essential. The plasma display panel is generally assumed to have a product life of about 10 years. If a small amount of the above-mentioned gas is generated from the component material during that period, the function will be degraded. Therefore, it is necessary that the getter encapsulated therein has no long-term decrease in gas absorption capacity, that is, has a long life.

[0004] As a getter material, for example,
As disclosed in JP-A-5-17293, alloys such as Zr-Fe-V, Zr-Al-based, Zr-Ni-based, and Zr-Fe-based have been developed. Since it is necessary to increase the reaction area of these alloys as much as possible, powders having an average particle diameter of 100 μm or less are usually formed into pellets for convenience of handling. No. 3,652,317 and U.S. Pat.
No. 3,856,709 discloses a method for manufacturing a deformed getter in which a granular material of a getter alloy is placed on a thin strip-shaped substrate and pressed.

[0005] Pellet getters are generally produced by press molding, but can only be produced up to about three times their thickness. Also, it is difficult to manufacture a tool having a diameter of 1 mm or less due to restrictions on manufacturing of a forming tool such as a die or a punch.

According to the above-mentioned US patent specification, a strip-shaped getter having a thickness of about 0.2 mm can be manufactured by the manufacturing method.
To a few mm. Furthermore, it is possible to make the slit narrower, but in that case, the yield is greatly reduced due to the cutting allowance, which is not suitable for industrial production. All of the above getters have no flexibility in shape change, and because the gas absorbing alloy is entirely exposed, it may collapse during handling during assembling work into equipment or during use in equipment. It may come off and come apart, causing unexpected damage to the equipment. In particular, in the plasma display panel, the loose powder moves to the front surface of the panel to inhibit the generation of plasma, and the shadow of the powder is reflected to deteriorate the image quality.

[0007]

DISCLOSURE OF THE INVENTION The present invention can be easily formed into various shapes and dimensions, and the alloy is not peeled or released during handling up to assembling into equipment and during use in equipment. An object of the present invention is to provide a getter that does not occur and a manufacturing method capable of mass-producing the getter at low cost.

[0008]

SUMMARY OF THE INVENTION The gist of the present invention is characterized in that it comprises a case having an opening, and a gas-absorbing alloy powder body contained in the case and integrally formed with the case. To get a gas absorption getter.

The case is desirably made of a metal having good heat resistance and workability, for example, a thin plate of iron, nickel, copper, aluminum, magnesium, titanium, cobalt, zirconium, or an alloy thereof. Further, this case may be a porous one having a large number of small-diameter through holes.

The overall shape of the getter of the present invention is linear, rod-like or band-like (including those cut into appropriate lengths), and its cross section (cross section perpendicular to the long axis) is circular or elliptical. Or any shape such as a polygon.

The present invention also provides a method of forming a thin metal plate into a cylindrical shape, filling the inside with a gas-absorbing alloy powder, and rolling, drawing, pressing or cutting, or working by two or more of these steps. The above-described method for manufacturing a getter ”is summarized.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1A to 1F are views showing some examples of a cross section perpendicular to the longitudinal direction of a getter 1 of the present invention (hereinafter simply referred to as a cross section). Each of the getters comprises a case 2 and a gas-absorbing alloy powder 3 filled in the case 2 (hereinafter referred to as "gas absorbent"). In the illustrated example, at least one portion of case 2 includes:
There is an opening for bringing the gas absorbent 3 into contact with the outside air.
This is achieved by using any one of the slits 4 provided at the joints at both ends of the case without making close contact with each other, a large number of through holes 4-1 provided in the case itself, the cutout 5 shown in FIG. 2, or a combination thereof. Good.

1 (a) shows a circular cross section, FIG. 1 (b) shows an elliptical cross section, FIG. 1 (c) shows a square cross section, FIG. 1 (d) shows a rectangular cross section, (E) is a triangle. The shapes (b) and (d) can be further flattened to form a so-called band (tape). Further, the opening may be enlarged as shown in FIG. In short, the cross-sectional shape can be variously changed depending on the use of the getter.

The getter is heat-treated at about 200 to 700 ° C. before use to activate the gas absorbent. Therefore, the material of the case 2 needs to have heat resistance that does not deform at that temperature. In addition, in order to perform a molding process described later, a material having high workability is desirable. Such materials include, but are not limited to, the metals or alloys described above.

The thickness of the case depends on the size of the getter but may be about 0.05 to 1 mm. The filling ratio of the gas absorbent can be increased as the case is relatively thin.

The type of the gas absorbent 3 is arbitrary. The aforementioned
Gas absorbing alloys such as Zr-Al, Zr-Ni, Zr-Fe and Zr-Fe-V can be used. Although powders and granules of these gas absorbing alloys are used, their shape and particle size are not particularly limited.
In the case of a spherical shape, the shape may be, for example, about 5 μm to 1 mm. Fine particles of less than 5 μm are easily oxidized and are difficult to handle in the air, and if they exceed 1 mm, the surface area is reduced and the gas absorption capacity is reduced. In the case of a flake shape, the thickness may be about 5 μm to 1 mm. Note that in order to increase the packing density, it is desirable that powders having different shapes and a shape close to a sphere are mixed as much as possible.

The slits 4 are for allowing the gas absorbent to come into contact with the outside atmosphere and exhibit its function (absorption of gas in the atmosphere). Therefore, many small holes (vents) may be provided instead of or in addition to the slits. The width of the slit or the diameter of the vent hole does not necessarily need to be smaller than the size of the gas absorbent to be filled. However, as shown in FIG.
It is desirable to fit inside the line L connecting the outer edges of the case.

Although the gas absorbing alloy is extremely hard, in the getter of the present invention, the particles of the gas absorbing alloy are not only entangled with each other in the process of being integrally formed with the case, but also bite into the portion in contact with the case. become. Therefore,
As shown in FIGS. 1 and 2, even if the opening is large, the gas absorbing alloy does not peel off. However, if the gas absorbent projects outside the line L connecting the outer edges of the case,
At the time of handling, there is a possibility that a part of the gas absorbent may fall off due to mutual contact of getters or contact with other objects.

When a long getter manufactured continuously by a roll forming method or the like to be described later is used after being cut to an arbitrary length, the cut end has an open shape as shown in FIG. . In this case, the opening (cut) 5 serves as a vent. In addition, even if there is an opening at the end, if the filled gas absorbent is prevented from being exposed to the outside from the end face of the case, there is no danger of peeling, but for example, FIG.
As shown in (2), the end of the case may be swaged. In addition, the getter as shown in FIG. 2 does not necessarily need the slit or the through hole of the case, but may provide them.

The getter of the present invention can be manufactured by various methods. For example, a hollow material (pipe) serving as a case is first prepared, a gas absorbent is filled therein, and the resultant is compressed and integrated by a press or the like. May be. In this case, the pipe is previously provided with a vent or / and a slit. If it is used as it is (without subsequent processing) as a getter, no particular workability is required for the material of the case, and the material may be ceramics or glass.

A preferable manufacturing method from the viewpoint of the production efficiency and the variability of the getter shape is the roll forming method described below.

The roll forming method is a method used for manufacturing an electric resistance welded steel pipe or the like. As shown in FIG. 3, a belt-like thin plate (case material) 6 is formed into a drum-shaped roll 8, a drum-shaped roll 9, 10
This is a method of gradually forming a cylindrical shape by the method described above. During the molding, the filler (gas absorbent) 3 is supplied from the hopper 7 to the inside, and finally a long getter of a predetermined shape can be continuously manufactured.

FIG. 4 schematically shows a cross section of the getter in the forming process of roll forming. Forming up to the same figure (b) by roll forming method, then
By a drawing method (drawing method) or the like, it may be processed into a small diameter as shown in (c). Furthermore, a flat shape (a band shape) such as an ellipse can be formed by rolling, pressing, or the like. Cut the long material obtained in this way to any length,
Product getter.

If a metal plate provided with a vent hole in advance is used as the material of the case, the slit of the molded product getter may not be necessarily provided.

[0025]

[Example] A gas absorbing alloy having a composition of V: 18 wt%, Ni: 1.5 wt%, Fe: 3.5 wt%, balance: Zr was melted in a vacuum induction furnace, ingoted in a vacuum, and pulverized in an argon atmosphere. Average particle size 50
μm powder (gas absorbent).

As a case material, a plate of pure nickel having a width of 7 mm and a thickness of 0.5 mm is used, and is formed into a cylindrical shape by a roll forming method.
It was molded to an outer diameter of 2.2 mm. The slit width at the joint of the case was about 0.1 mm. From the molded material, the following test materials were produced.

(1) Specimen 1 The above molded material was subjected to wire drawing to produce a getter having an outer diameter of 0.8 mm (case thickness of 0.2 mm). In this state, the filling amount of the gas absorbent was 0.73 g / m. This getter was cut into a length of 50 mm to obtain a test material. In addition, this test material has a slit having a width of about 30 μm at the joint of the cases.

(2) Specimen 2 The above molded material was subjected to press working to 2.3 mm in width and 1.5 mm in thickness.
And cut into a length of 50 mm to obtain a test material. At this time, the filling amount of the gas absorbent was 4.3 g / m, and the width of the slit at the joint of the case was about 0.6 mm.

(3) Specimen 3 The above molded material was rolled with a roll having a diameter of 250 mm so that the joint (slit) of the case was in contact with the roll, and the width was 3.7 mm.
The specimen was cut into a flat shape having a thickness of 0.5 mm and a thickness of 0.5 mm, and cut into a length of 50 mm. At this time, the filling amount of the gas absorbent is 2.6 g / m, and the slit of the joint of the case is enlarged to expose the gas absorbent over the entire width (however, the gas absorbent projects outside the extended line outside the case). Not).

The following test materials were prepared separately for comparison.

(4) Specimen 4 The above gas absorbent was filled in a mold having an inner diameter of 3 mm, and was filled with 5 t / cm ²
To obtain a test piece in the form of a pellet (small column) having a diameter of 3 mm and a length of 4 mm.

The following tests were performed using the above test materials 1 to 4. That is, the test material was placed in a tube having an inner diameter of 5 mm and a length of 150 mm, and argon gas (containing 3000 ppm of N ₂ and 1000 ppm of CH ₄ as impurities) was supplied from one end of the tube heated to 450 ° C. at 10 ml / min. At a rate of The test materials are
The amount of the gas absorbent inside was adjusted so as to be all the same (1 g). During this test, impurity gas contained in the gas discharged from the outlet of the tube was analyzed by gas chromatography. Table 1 shows the results.

In addition, in order to evaluate the strength of the getter (test material), the length of the test materials 1 to 3 was adjusted to 4 mm, which is the same as that of the test material 4, and the rattra value was obtained. The method is as follows.

The weight (A) of each of the five test materials 1 to 4 was measured. Next, these were put into a basket of a rattling machine and rotated 100 times at a rotation speed of 90 rpm. Thereafter, the test material was taken out of the basket and the total weight (B) was measured. The rattra value (S) is obtained by the following formula. The smaller this value is, the smaller the powder particles of the gas-absorbing alloy that have fallen from the test material. The test results are also shown in Table 1.

S = {(AB) / A} × 100 (%)

[0036]

[Table 1]

As shown in Table 1, there is almost no difference between the gas absorption capacities of the test materials 1 to 4. However, the test material 4 (pellet-shaped getter in which the gas-absorbing alloy is exposed) has a rattling value of 5.5, whereas the getter of the present invention (test materials 1 to 3) is significantly smaller. In addition, since the above-mentioned rattra test is a test which is extremely severe compared with the conditions of handling and use of the getter, a rattra value of about 1% poses no practical problem at all.

As described above, although the getter of the present invention is housed in a case, it has the same gas absorption capacity as a conventional pellet-type getter, and has much more durability (peeling resistance). Beats.

[0039]

Since the getter of the present invention is housed in a case and integrally formed, the gas absorbent does not peel off or separate during handling and use. Moreover, since it can be formed into a desired shape, it can be formed into various shapes according to the purpose of use. The getter of the present invention exhibits its function stably for a long time as a getter that is placed in a sealed device such as a plasma display panel and absorbs gas inside. This getter can be manufactured by various methods, but can be mass-produced at a low cost, particularly when manufactured by a roll forming method.

[Brief description of the drawings]

FIG. 1 is a view schematically showing several examples of the cross-sectional shape of a getter of the present invention.

FIG. 2 is a view schematically showing several examples of the longitudinal sectional shape of the getter of the present invention.

FIG. 3 is a diagram illustrating a roll forming method for manufacturing a getter of the present invention.

FIG. 4 is a diagram showing a cross-sectional shape in a manufacturing process of the getter of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Getter, 2 ... Case, 3 ... Gas absorption alloy, 4 ... Opening (slit), 4-1 ... Opening (through hole) 5 ... Opening (cut), 6 ... Case material (metal thin plate) 7 ... Hopper, 8: drum-shaped roll, 9: drum-shaped roll, 10: drum-shaped vertical roll

Continued on the front page F term (reference) 4D020 AA02 AA08 AA10 BA01 BA03 BA04 BA05 BA06 BB01 CA05 CC06 CC14 DA01 DA02 DA03 DB01 DB02 DB03 DB04 DB07 DB10 DB20 4G066 AA15B AA16B AA20B AA23B AA27B BA12 CA37 CA43 FA51 FA20 A20 FA20 FA25 5C035 JJ05 JJ11 JJ15 5C040 HA08 MA26

Claims (4)

[Claims] 1. A gas-absorbing getter comprising a case having an opening, and a gas-absorbing alloy powder contained in the case and integrally formed with the case. 2. The getter according to claim 1, wherein the case is made of a thin metal plate. 3. The getter according to claim 1, wherein the overall shape is a line, a bar, or a band, and the cross section perpendicular to the major axis is a circle, an ellipse, or a polygon. 4. A method in which a metal thin plate is formed into a cylindrical shape, and the inside thereof is filled with a gas absorbing alloy powder, and processed by rolling, drawing, pressing or cutting, or two or more of these steps. A method for manufacturing a getter according to claim 3.