JPH0135228B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a spiral gasket that can exhibit high sealing performance even with low tightening surface pressure. As shown in FIGS. 1 and 2, a conventional general spiral gasket consists of stacking a tape-shaped filler material 1 and a tape-shaped metal hoop material 2 and winding them in a spiral shape. The winding terminal end 22 is fixed by spot welding or the like, and the filler material 1 and the metal hoop material 2 are bent in a "dog" shape at the center in the width direction thereof. Therefore, such a spiral gasket prevents gas leakage by the spring action of the metal hoop material 2 and the sealing action of the filler material 1, and is highly elastic and can withstand high tightening surface pressure. Therefore, it is used for general gas piping, but it requires a considerably high tightening surface pressure in order to obtain a high degree of sealing. By the way, as the filler material 1 for such a spiral gasket, general asbestos paper obtained by making paper from asbestos, a binding material (rubber, etc.) and a filling material (kaolin, clay, etc.), wax, etc. Asbestos paper that has been treated to be impermeable with oils and fats is used. However, the spiral gasket using general asbestos paper as the filler material 1 cannot be said to have sufficient sealing performance, while the spiral gasket using impermeable asbestos paper shows improvement in sealing performance. However, a tightening surface pressure of about 800 Kl/cm2 is required to fill the gap between the filler material 1 and the all-metal hoop material ² due to the flow of oil and fat, and if heat is applied, the oil and fat will flow out and decompose. Therefore, there were problems such as sometimes the sealing performance was inferior to that using ordinary asbestos paper. In view of the above problems, the present invention was made with the purpose of providing a spiral wound gasket that can exhibit high sealing performance even with low tightening surface pressure and has excellent heat resistance. The gist is that the surface is coated with a coating thin film made of a rubber elastic material containing an inorganic filler. Hereinafter, the present invention will be explained in detail based on FIG. 3 showing one embodiment. That is, as shown in the figure, the spiral gasket of the present invention is made by stacking a tape-shaped filler material 1 whose entire surface is covered with an elastic coating thin film 3 containing an inorganic filler and a tape-shaped metal hoop material 2. The gasket is wound in a spiral shape, and the starting end 21 and ending end 22 of the gasket are fixed by means such as spot welding in the same manner as the conventional gasket shown in FIG. 2 is bent in a "dog" shape at the center part in the width direction, and the coated thin film 3
The metal hoop material 2 and the mating bearing surfaces 4a and 4b on both sides of the gasket are in close contact almost entirely. The filler material 1 is a tape-shaped material made of the above-mentioned general asbestos paper, and preferably has a thickness of about 0.6 mm. The metal hoop material 2 is made of, for example, stainless steel, which is commonly used as a metal hoop material for gaskets in the past, and preferably has a thickness of about 0.2 mm. The coated thin film 3, which is a feature of the present invention, is made by blending an inorganic filler with an elastic binder, and adding a thickener and other auxiliary materials as necessary to coat the filler material 1 with a coating liquid. It is formed by coating the surface (i.e., the front, back, and both sides), and various synthetic rubbers such as natural rubber and styrene-butadiene latex are preferably used as the binding material depending on the purpose of the specification. For example, if oil resistance is particularly required, nitrile rubber is used, if corrosion resistance is required, fluororubber is used, and if cold resistance is also required, silicone rubber is appropriately selected and used. As the filler, clay minerals such as talc, kaolin, and mica, which have layered crystals and are smooth and easily arranged along the mating seating surfaces 4a, 4b and the metal hoop material 2, are preferably used. These clay minerals are also desirable because they have excellent heat resistance and chemical resistance. Further, as the thickener, for example, sodium polyacrylate or the like is preferably used. When preparing the coating liquid, add 10 parts of binder (parts by weight,
It is desirable that the filler be used in a proportion of 10 to 100 parts. When the proportion of filler becomes less than 10 parts and the proportion of binder increases relatively, sealing performance improves, but heat resistance and chemical resistance decrease, resulting in increased relaxation. On the other hand, if the proportion of the filler exceeds 100 parts, the sealing performance will deteriorate. The thickness of the coated thin film 3 to be formed is desirably about 1/10 or less of the thickness of the filler material 1, preferably about 5 to 50 μm. This is because if the coating thin film 3 becomes thicker than the above, the sealing performance will improve, but the disadvantage that relaxation will also increase will become more noticeable. In the spiral gasket of the present invention having the above structure, the entire surface of the filler 1 is coated with a coating thin film 3 made of a rubber elastic material containing an inorganic filler,
Even if a small tightening surface pressure is applied, this coated thin film 3
is in close contact with the metal hoop 2 and the mating seating surfaces 4a, 4b, so high sealing performance can be exhibited. In particular, the inorganic filler contained in the coated thin film 3 has layered crystals and is easily arranged in a plane, so the degree of adhesion of the coated thin film 3 is excellent. Contact surface leakage from the gap 4b,
Also, leakage from the contact surface from the gap between the filler material 1 and the metal hoop material 2 can be almost completely prevented. Moreover, unlike oils and fats, the inorganic filler contained in the coating thin film 3 does not leak out or decompose due to heat, so it can exhibit stable sealing performance even in a hot atmosphere and has excellent heat resistance. It is something that In order to prove the effects of the spirally wound gasket of the present invention, examples are given below. Experimental Example 1 A coating liquid having the proportions shown in Table 1 below was prepared and applied to the entire surface of a filler material made of general asbestos paper with a thickness of 0.6 mm to form a thin coated film. The thickness of this coated thin film was estimated to be 15 μm on average from the difference in weight of the filler material before and after coating. Next, the all-metal hoop material (SUS304) with a thickness of 0.2 mm and the filler material covered with the above-mentioned coating thin film are layered and wound into a spiral shape, and after spot welding the starting end and ending end of the winding, By bending the center part into a dogleg shape, the outer diameter is 110 mm and the inner diameter is 90 mm.
A spiral gasket without inner and outer rings with a width (gasket thickness) of 4.5 mm was manufactured. This spiral gasket was clamped between mating seating surfaces with a seating surface roughness of Z4S, and 20 kg/cm ² of nitrogen gas was loaded to measure the amount of leakage at room temperature at each tightening surface pressure. The results were as shown in Table 2 below. Next, the tightening surface pressure of this spiral gasket is 600
After measuring the leakage amount in kg/cm ² at room temperature under the same conditions as above, heating at 200℃ for 10 hours in an electric furnace,
The amount of leakage was measured at a tightening surface pressure of 600 kg/cm ² after heating. The results were as shown in Table 3 below. For comparison, we fabricated a spiral gasket of the same size using general asbestos paper as a filler material and a spiral gasket of the same size using impermeable treated asbestos paper, and tested them at room temperature in the same manner as above. The amount of leakage and the amount of leakage after heating were measured. The results were as shown in Tables 2 and 3 below.

【table】

【table】

[Table] From Table 2 above, it can be seen that the spiral gasket of ^the present invention has a leakage amount of
1/10th of the conventional gasket using impermeable asbestos paper
Below, 1/200 ~ of gaskets using general asbestos paper
It can be seen that it exhibits extremely excellent sealing performance even under low tightening surface pressure, which is less than 1/300. From Table 3 above, it can be seen that the spirally wound gasket of the present invention can exhibit unchanged sealing performance even after heating and has excellent heat resistance. In addition, in the present invention, the filler of the spiral gasket is
Although we have explained the case of asbestos paper as the material, filler materials other than asbestos paper, such as glass fiber, rock wool, metal fiber, inorganic fiber such as carbon fiber, phenolic resin fiber, aromatic preamide fiber, polyester fiber, rayon, etc. For fiber materials made of a single or a combination of organic fibers such as fibers and vegetable fibers,
By blending binder and solid plugging material, paper making method or
It is also applicable and effective to asbestos-free filler materials obtained by hot roll forming.

[Brief explanation of drawings]

Fig. 1 is an enlarged partially cutaway front view of a conventional spiral gasket, Fig. 2 is a plan view of the same gasket, and Fig. 3 is a partially cutaway enlarged front view of a conventional spiral gasket.
The figure is an enlarged partially cutaway front view of one embodiment of the spiral gasket of the present invention. 1...Filler material, 2...Metal hoop material, 3...
...Coating thin film, 4a, 4b...Mating bearing surface.

Claims (1)

[Claims] 1. In a spiral gasket in which a tape-shaped filler material and a tape-shaped metal hoop material are stacked and wound in a spiral shape, the entire surface of the filler material is covered with a thin coated film made of a rubber elastic material containing an inorganic filler. A spiral gasket characterized by being coated with.