JPS60260415A - Expanded graphite material - Google Patents

Abstract

PURPOSE:To obtain an expanded graphite material having improved strength and corrosion resistance by coating the surface of expanded graphite with the mixture of molten fluororesin with inorg. powder. CONSTITUTION:Expanded graphite is preburned at a prescribed temp., and a mixture of molten fluororesin with inorg. powder is uniformly sprayed on the whole surface of the graphite and burned in a high temp. atmosphere to obtain the desired expanded graphite material. Perfluoroalkoxy resin, tetrafluoroethylene-ethylene copolymer resin or the like are used as the fluororesin, and powder of talc, mica, silica or the like as the inorg. powder. The expanded graphite material is not unexpectedly damaged even when influenced from the outside during transportation of fixing, so the handling property is improved.

Description

[Detailed Description of the Invention] B) Technical Field of the Invention The present invention relates to an expanded graphite material used for sealing members such as gaskets and gasstats, or sealing tapes, and more specifically relates to an expanded graphite material used in melting the expanded graphite material. This invention relates to an expanded graphite material that is coated and protected with a coating material that is a mixture of fluororesin and inorganic powder.

(B) Background of the Invention It has been known that the expanded graphite material described above is particularly suitable for sealing members because it has appropriate elasticity and flexibility in addition to heat resistance.

However, on the other hand, this expanded graphite material has brittle properties, so it often cracks or chips during transportation, installation, or handling. A great deal of care must be taken in handling, and especially when the mounting operation is mechanized, it is easy to be damaged by the vibrations of the machine, the gripping force of the robot, etc.

In addition, expanded graphite material is inherently corrosion resistant, but not only does it have poor corrosion resistance against strong acids, but when it is used attached to -q equipment, when it is removed, the contact surface of the equipment may be damaged. The problem was that the surface was partially peeled off and could not be reused because it adhered due to baking etc.

(c) Purpose of the Invention Therefore, the object of the present invention is to provide an expanded graphite material free of causes such as damage caused by external forces, decrease in corrosion resistance, increase in sliding resistance during use, and impossibility of reuse.

(D) Summary of the Invention The present invention is an expanded graphite material in which a part or all of the surface of the expanded graphite is coated with a coating made of a mixture (blended) of a molten fluororesin and an inorganic powder. In this case, the molten fluororesin includes perfluoroalkoxy resin (PFA), tetrafluoroethylene-ethylene copolymer resin (ETFE), vinylidene fluoride resin (PVdF), etc. Powder is talc,
It means a powder made of mu-free materials such as mica and silica.

(E) Effects of the Invention According to this invention, since the surface of expanded graphite is protected by a covering material ``Q'' made of a mixture of molten fluororesin and inorganic powder, the strength of this expanded graphite material itself is This improves handling properties and prevents unexpected damage even if the product is subjected to external influences such as vibration or impact during transportation, installation, or handling.

Furthermore, since the above-mentioned coating material with good chemical resistance can withstand strong acids, the expanded graphite is always used in a protected state, and its corrosion resistance is reliably improved. moreover,
The non-adhesive properties of this coating material do not damage the surface even when it is attached and removed, making it not only reusable but also
Low friction properties reduce sliding resistance with mating parts,
Moreover, since the strength of the coating material is increased by the mixed inorganic powder, peeling and peeling of the coating material can be eliminated, and the sliding resistance strength is increased, making it particularly suitable as a sealing member.

(f) Examples of the invention An example of the present invention will be described in detail below based on the drawings.

The drawing shows an expanded graphite material used for a sealing member, and in FIG. It is formed into an inner and outer double structure with a covering material 3 that protects the covering.

This coating material 3 was made of 50 wt% PFA (trade name MP-10 manufactured by Mitsui Fluorochemical Co., Ltd. was used as PFA). ] and Tatag 550wt% talc manufactured by Nippon Talc Co., Ltd. were used. ] was used. Incidentally, talc is originally a low-friction material like ETFE, but by blending talc as in Coating Material 3, the mechanical strength (resistance to peeling) is increased compared to that of only ETFE. ) can be increased by about 3 times.

The coating thickness varies depending on the application, but is usually 20
It is suitable to set it to about 20C1m.

For example, if only ease of handling is considered, this is 20
A coating thickness of approximately 50 μm is suitable, and in cases where there is a risk of inducing pitting corrosion, a coating thickness of approximately 50 μm can solve the problem.In addition, in cases where there is a possibility of inducing pitting corrosion, a coating thickness of approximately 200 μm can solve the problem. can.

Next, a case where electrostatic powder coating is used will be described as an example of the coating means.

As shown in Fig. 2, first, an expanded graphite 2 provided in the shape of a disc-shaped sealing member is placed in a high temperature atmosphere of 500°C for 30 minutes.
After baking for 0 minutes, as shown in FIG. 3, the powder of the coating material 3 is sprayed uniformly over the entire outer surface of the coating material 3, as shown in FIG.
Thereafter, the sea urchin shown in FIG. 4 is baked by leaving it in a high temperature atmosphere of about 300° C. for about 20 minutes, and then it is naturally cooled or forcedly cooled, and the coating operation is completed and covered. In this way, the desired expanded graphite material can be obtained.

In this invention, electrostatic powder coating is preferred as a method for coating the expanded graphite 2 with the coating material 3.[Extrusion is preferred because it allows easy blending of inorganic powder and provides a uniform coating thickness. This is because it is easy to obtain. .

The expanded graphite material configured in this manner exhibits both the heat resistance, elasticity, and flexibility of the expanded graphite 2 and the various properties of the coating material 3, such as chemical resistance and low coefficient of friction. This results in a high-performance sealing member, and since the coating does not cause damage or damage, it is certainly easy to handle.

FIGS. 5 to 7 show other embodiments of the present invention, and FIG. 5 shows only both end surfaces of the expanded graphite 52 having contact dimensions.
50 wt% [Afron COP, a trade name manufactured by Asahi Glass Co., Ltd., was used as ETFE.

] and 5 Qwt% silica are shown, showing an expanded graphite material 51 as a gasket which is reusably coated and protected by a coating material 53 of 20 to 50 μm, and by disposing silica, flow and slippage of the seat surface can be suppressed. Can be done. Figure 6 shows the ETF for only the inner peripheral surface of expanded graphite 62 for stem torque.
This shows a monoexpanded graphite material 61 suitable as a valve plug, which is coated with a coating material 63 of 20 μm thick and made of a mixture of E20wt:% and 80wt% talc to reduce the frictional resistance of sliding parts. The figure shows ETFE5Qw, t% in the filler 72 of the spiral gas stand door 1 using expanded graphite material.
An example of use will be shown in which a covering material 73 made of a mixture of 20 wt % of talc and 30 wt % of silica is coated and protected by 20 μm to improve workability.

In addition, in this invention, the blending amount of the inorganic powder blended into the coating material is preferably in the range of 10 to 80 wt%. This is because when the inorganic powder becomes 10 wt % unvortexed, the influence of only the molten fluororesin tends to appear, and when it exceeds sowt %, the advantages of the molten fluororesin cannot be utilized.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, FIG. 1 is a longitudinal cross-sectional view of expanded graphite material used for the sealing member, FIGS. 2 to 4 are explanatory diagrams showing the manufacturing process, and FIGS. 5 to 4
FIG. 7 is a longitudinal sectional view showing another embodiment of the invention. 1.5j, 61... Expanded graphite material 2.52.62... Expanded graphite 3.53.63.73... Covering material 71... Spiral gasket 72... Filler Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 1 Figure 6 1 Figure 7 1

Claims (1)

[Scope of Claims] 1. An expanded graphite material characterized in that the surface of expanded graphite is coated with a coating material made of a mixture of molten fluororesin and inorganic powder.