JPS5849656A - Composite seal material containing swellable graphite - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] The present invention relates to a pagination of expanded graphite sealing material.

Conventionally, expanded graphite molded bodies are known in the form of sheets, tapes, and sheets with metal reinforcing plates, and all of them have good sealing effects on static sealing surfaces, but they are difficult to seal on dynamic parts. As for the material, the expanded graphite molded body is mainly based on mechanical entanglement between expanded graphite particles, so it is insufficient in terms of strength. Since the particles have a small bulk density, there is a large amount of bulk when filling the mold, making it difficult to mold thick products.

On the other hand, conventional sealing materials machined from carbon materials have high rigidity and do not have the same compressive recovery properties as expanded graphite, so they are inferior in terms of sealing effectiveness, and the rounding process of cutting from lumps increases. There was a problem.

An object of the present invention is to solve the problems of the conventional products mentioned above.

The present inventor has discovered that by mixing a small amount of organic binder with expanded graphite particles crushed to a bulk density i of 0.08 f/C1n" or higher and heat-treating them after molding, the mechanical strength is increased, and this is applied to dynamic seal parts. found that it is possible.

The present invention relates to a composite sealing material containing expanded graphite, which is formed by mixing crushed expanded graphite particles and an organic binder, molding the mixture, and curing the molded material by heating.

The expanded graphite used in the present invention is natural scaly graphite.

Graphite intercalation compound g-/C is obtained by treating pyrolytic graphite etc. with strong acid.
m” is used.

Expanded graphite can be ground to a bulk density of 0.08 to 0.4' using a high-speed rotary blade such as a Henschel mixer or a non-mer type grinder. /Cm''. If the bulk density is less than 0.08 y-A, it will be difficult to mold thick products and the mixability with the organic binder will be insufficient.

The organic binder is added in an amount of 3 to 15 parts by weight, preferably 5 to 10 parts by weight, to the pulverized expanded graphite particles and mixed well.

If the amount of organic binder added is too small, the increase in strength will be insufficient, and if it is too large, the advantages of expanded graphite will be impaired, such as a decrease in compression recovery properties. The organic binder can be used in either powder or liquid form, but from the viewpoint of workability, powder form is preferred. There are no particular restrictions on the type, but phenolic resin,
Thermosetting resins such as epoxy resins and melamine resins are preferred.

In the present invention, it is preferable to add short carbon fibers of 0.5 to 5 mm when mixing the expanded graphite and the organic binder because this increases mechanical strength and improves wear resistance as a seal.

The carbon fiber used may be either polyacrylonitrile type or tar pitch type. When carbon fibers are added, it is preferable to use a Henschel mixer for the mixing operation since uniform mixing can be achieved.

The mixture is weighed to a predetermined weight xIi' and placed in a mold under a surface pressure of 100~
500 Ky/cm" pressure fA type 4 tL.M
Pressure molding is also possible, but from the viewpoint of efficiency, it is preferable to perform cold molding and then heat treatment to harden the organic binder. For heat treatment, the molded body is placed in a heat curing furnace and the temperature is raised from room temperature to 150°C over about 1 hour, held at that temperature for 30 minutes, and then raised to 200°C within 30 minutes. , store at that temperature for 30 minutes, and then lower the temperature to below 50°C over an hour or more. The firing conditions are appropriately set depending on the shape of the product, the amount of organic binder, etc.

Next invention? lI-Explained by example.

Example 1 Expanded graphite 300 with bulk density 0.026 y-/(7)8
I was crushed for 2 minutes using a Henschel mixer to obtain a bulk density of 0.
A pulverized expanded graphite of 12Y/Cm8 was obtained. 1 for this crushed material
Novolac type phenol resin powder No. 51 (SM-107A manufactured by Mitsubishi Gas Chemical Co., Ltd.) was added and mixed uniformly for 10 minutes using a V-type blender. This mixture 20y- was put into a cylindrical mold with an outer diameter of 40φ and an inner diameter of 32φ, and the surface pressure was 400Kp/
A molded body with a height of 25 quakes was obtained by pressurizing with crn'. After holding the molded body at 70°C for 60 minutes.

The temperature was raised to 160°C in about 30 minutes and held for 30 minutes.

Next, the temperature was raised to 200°C for about 30 minutes and held for 30 minutes.

The temperature was lowered to 50°C in about 60 minutes and then taken out. The expanded graphite resin composite sealing material thus obtained had a compressive fracture strength approximately 23 times as strong as an expanded graphite molded product of the same shape, and did not cause any problems during normal handling. Furthermore, as a result of a 500-hour durability test in which Motoichi was installed as a mechanical seal, it showed good performance with no leakage or galling of the shaft or mating material.

Example 2 Expanded graphite 300 with bulk density o, 01 sy/cm"
0.09 t of y- in a swing mill mill
/C1n'' expanded graphite pulverized product was obtained.
Add novolac type phenolic resin powder (5-8M-102A, manufactured by Mitsubishi Gas Chemical Co., Ltd.) of F, and further chop it into 3 lengths of 15I, and then add carbon fiber (C.103, manufactured by Kureha Chemical Co., Ltd.) lJIL.
The mixture was mixed for 3 minutes using a Henschel mixer to obtain a homogeneous mixture. This mixture was molded in the same mold as in Example 1 under the same conditions to obtain a molded product with -g of 2610 m.

This molded body was heated and cured under the same curing conditions as in Example 1 to obtain an expanded graphite resin composite sealing material. The strength of Motoichi was about 1.7 times that of the sealing material obtained in Example 1.

The results of the seal property test conducted by Motoichi showed good results, with no leakage or impact on the mating material. In terms of abrasion resistance, this product tended to be much better than the sealing material of Example 1, which did not contain carbon fibers.

The sealing material containing expanded graphite according to the present invention has significantly increased mechanical strength compared to the conventional molded product made of expanded graphite alone, so it can be applied to dynamic sealing parts in addition to static parts. Become.

Therefore, static backings that are subject to strong vibrations, such as automobile exhaust tubes, pumps, etc.

It can be expected to have excellent effects as a packing material for stuffing boxes in structures such as valves, or as a mechanical sealing material for general machinery.

7- =321-

Claims (1)

[Claims] 1. A composite sealing material containing expanded graphite that is obtained by mixing crushed expanded graphite particles with an organic binder, molding it, and curing it by heating.