JPH0419255B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] When using a sealing material for a bearing, the present invention always supplies oil to the tip of the lip to ensure smooth rotation.
The present invention relates to a bearing sealing material that reduces torque fluctuation, prevents seizure, and improves wear resistance, and a method for manufacturing the same.

[Conventional technology]

Conventionally, sealing materials for bearings are installed in a predetermined position, and the tip of the seal lip slides to prevent water, mud, sand, etc. from entering from the outside, as well as preventing internal grease, etc. from flowing out. played a role.

However, the oil flow to the seal lip, which improves sealing performance, is cut off, and when used for long periods of time or at high speeds, the seal lip may seize, and the torque fluctuation range becomes large, causing noise due to uneven rotation. It was hot.

For this reason, the rubber compound that makes up the bearing sealant is impregnated with oil, and oil is automatically supplied to the seal lip to lower the coefficient of friction and prevent seizure.
Methods have been used to improve wear resistance and prevent noise. However, even if oil is added to the rubber compound to impregnate the rubber compound, during the work process of roll kneading and molding with a molding press,
The oil may cause uneven kneading, and the added oil may flow out due to pressure, and the amount of oil impregnated is very small at 1 to 5 parts by weight, and it is impossible to control the amount. Even if the material is used, the desired purpose is achieved initially, but as the oil supply gradually decreases, many problems occur, such as the seal lip seizing and poor adhesion to the core metal during molding. There were flaws.

Therefore, the inventor has developed a sealing material for bearings that eliminates these drawbacks, constantly supplies oil to the seal lip, smoothes rotation, reduces torque fluctuations, prevents seizure, and improves wear resistance. In order to provide a method, as previously described in detail in JP-A-60-30826, a rubber compound in which microcapsules containing a lubricant are dispersed is used and molded into a desired shape. We have invented a method for producing a sealing material for bearings, and a sealing material for bearings in which the microcapsules are dispersed.

[Problem that the invention seeks to solve]

However, the inventor filed an earlier application for JP-A-60-
No. 30826 (Japanese Patent Application No. 139230/1982) states that thermoplastic resins such as polyamide resins and polyacrylic resins are the most suitable resins for the purpose of the present invention for the microcapsules, and examples thereof are also given. , the thermoplastic resin microcapsules are destroyed by heat, but as they are gradually destroyed by the temperature rise, sufficient destruction is not achieved, and the surface portion is destroyed, but the inside is destroyed. It has the disadvantage that strict temperature control is required when molding it into a sealant.

The present invention eliminates these drawbacks, and the microcapsules containing the lubricant are not destroyed when kneaded with a rubber compound, but are easily destroyed when molded into a bearing sealant, and the lubricant oozes out. To provide a sealing material for bearings that allows oil to flow out and constantly supplies oil to the seal lip, smoothes rotation, reduces torque fluctuations, prevents seizure, and greatly improves wear resistance. .

[Means for solving problems]

The present invention is a method for manufacturing a sealing material for a bearing, which is characterized in that it is molded into a desired shape using a rubber compound in which microcapsules containing a lubricant are dispersed, the microcapsules being melamine-based. This is a method for producing a sealing material for a bearing, which is characterized by being made of a thermosetting resin such as resin, phenolic resin, or urea resin.

In this case, the optimal size of the microcapsules is about 5 to 20 microns, but there is no particular limitation. Lubricating oil is encapsulated in these microcapsules, and when kneading the rubber dough and compounding agents, the microcapsules are mixed in and kneaded with a roll to disperse into the rubber compound to obtain the desired composition for molding. The interposed material is vulcanized and molded using a normal bearing sealing press to obtain a desired bearing sealing material.

[Function] A thermosetting resin such as a melamine resin, a phenol resin, or a urea resin is used for the outer skin of the microcapsules in order to exhibit workability and the various functions and effects mentioned above. Although it does not break down below 140°C, it rapidly breaks down when the temperature exceeds 140°C, and during the kneading process, the microcapsules containing oil will be destroyed despite the roll pressure. It is almost uniformly dispersed within the rubber fabric.

Furthermore, the temperature at which the microcapsules are destroyed is
The temperature is about 140℃, so when the rubber fabric and core metal are heated in a vulcanization press to vulcanize and mold a sealing material for a bearing in the desired shape, the membrane of the microcapsules is destroyed by the molding heat, and the inner encapsulation is destroyed. It is possible to obtain a bearing sealing material in which the oil is appropriately dispersed in the rubber compound. In addition, the melamine resin, phenol resin, urea resin, etc. have good compatibility with nitrile rubber, acrylic rubber, etc., which are often used as sealing materials for bearings, and the microcapsule outer skin remains in the form that remains after molding. However, the thin outer skin is easily destroyed by frictional heat during use of the bearing sealant, and serves to extract the lubricating oil contained therein and smoothen rotation. As described above, the resin of the present invention used for the outer skin of microcapsules exhibits pressure resistance against the pressure during rolling operation, but when vulcanizing and molding the rubber compound together with the core metal into the desired shape, it is necessary to In this case, the microcapsules are destroyed and the purpose of the present invention can be fully achieved.

The thickness of the outer skin of the microcapsules may be freely adjusted, and may be set to such a thickness that the microcapsules are completely destroyed by heat during rubber vulcanization molding.
Alternatively, a suitable number may be maintained in the form of a thin film without being destroyed, and destroyed by friction during use. In this case as well, thermosetting resins are very advantageous because they can be easily controlled.

Furthermore, in microcapsules containing a lubricant, by adding a small amount of thermoplastic resin, such as polyamide resin, polyacrylic resin, etc. It is more effective because it provides strong strength and can cover the fragility of thermosetting resin alone. In addition, in order to obtain appropriate strength as microcapsules, the optimum ratio of thermoplastic resin to thermosetting resin is about 20%.
An appropriate amount may be selected depending on the roll working conditions and vulcanization conditions during molding.

In addition, when lubricating oil is encapsulated in microcapsules, microcapsulation is facilitated by gelling the lubricant and encapsulating it in microcapsules. The particle size of microcapsules particularly suitable for the purpose of the present invention is between 5 and 20 microns, but
It would be very troublesome to incorporate liquid lubricant into this, but by gelling the lubricant, microcapsules can be easily created. Since it also has pressure resistance, it has the advantage that the outer skin of the microcapsules can be made thinner to withstand rolling operations, and the action of destroying the microcapsules due to temperature can be made easier. At this time, to gel the lubricant, a general oil gelling agent may be used, but for example, if silicic anhydride is used, it will not adversely affect the physical properties of the rubber since it is also used in the compounding of rubber. You can reach your goal.

[Effects of the Invention] In this way, the microcapsules containing the lubricant, which are ideally dispersed almost uniformly in the rubber compound, are destroyed or weakened during molding of the bearing sealant. Oil is dispersed inside the
When this oil is used as a bearing sealant, it gradually oozes out and helps smooth rotation. In this case, the optimal lubricant content is 15 to 20 parts by weight, but it was previously impossible to contain this amount.
According to the present invention, not only can it be easily contained, but also a larger amount can be contained if desired, and the amount can be freely controlled, and only the desired amount can be contained, so that it can be used in accordance with the conditions of use. It is very easy to set the optimum content according to the following. At this time, if the size of the microcapsule, the thickness of the outer skin, the breaking temperature, the molding time, etc. are combined, the optimum conditions can be met, and the rotation of the sealing material for the bearing can be made smooth, and the rotation can be made for a long period and at high speed. The present invention provides a method for producing an ideal sealing material for a bearing, which has excellent effects such as durability, no torque fluctuation, and no noise caused by uneven rotation.

Claims (1)

[Scope of Claims] 1. A method for producing a sealing material for a bearing, characterized in that it is molded into a desired shape using a rubber compound in which microcapsules containing a lubricant are dispersed; A method for manufacturing a bearing sealing material characterized by being made of a curable resin. 2. The method for manufacturing a bearing sealing material according to claim 1, wherein the microcapsules encapsulating a lubricant are made by adding a small amount of thermoplastic resin to a thermosetting resin. 3. The method for manufacturing a bearing sealing material according to claim 1, characterized in that the lubricant is gelled and encapsulated in microcapsules containing the lubricant.