JPH02305884A - Seal member for oil seal and its manufacture - Google Patents

Abstract

PURPOSE:To easily obtain the title member exhibiting stable sealing performance by uniformly orienting and dispersing fine particles of a first polymer that is solid at room temperature in a second polymer that is incompatible with the first polymer and shows rubber-like elasticity at room temperature. CONSTITUTION:A polymer A that is solid at room temperature (e.g. polystyrene) is kneaded with a polymer B that is incompatible with the polymer A and shows rubber-like elasticity at room temperature (e.g. polyethyl acrylate) at a temperature above the melting points of both polymers, so that the fine particles of the polymer A are uniformly dispersed in the polymer B to produce a mixture having a micro-disperse phase formed therein. A vulcanizing agent is incorporated into this mixture and kneaded. This kneaded material is put in a mold, vulcanized and molded in a state wherein the fine particles of the polymer A uniformly dispersed in the polymer B are oriented by applying a shear stress at a temperature near the softening point of the polymer A, thus giving a seal member 1 for oil seal, which slides on the periphery of a rotating or traversing shaft 5 to serve as a seal between the oil side and the atmospheric side.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a sealing member for an oil seal and a method for manufacturing the same, and particularly to a sealing member for an oil seal that slides on the outer periphery of a rotating or reciprocating shaft and connects the oil side and the atmosphere side of the shaft. The present invention relates to a sealing member for an oil seal that seals an oil seal and a method for manufacturing the same.

[Prior art and problems to be solved]-a. As shown in FIG. a seal member 1 made of an elastic material and having an annular seal lip portion 2 that moves to seal the oil side and the atmosphere side of the shaft 5;
It is comprised of a spring 3 that applies a force to the seal lip portion 2 of the seal member 1 to hold it against the shaft 5, and a metal ring 4 that is embedded in the seal member 1 and reinforces the seal member 1.

The sealing member 1 is conventionally manufactured by vulcanizing and kneading a rubber material 1) serving as a base material, adding a filler 12, a vulcanizing agent, and other auxiliary agents, and kneading the mixture. The ability of the seal IIs as an oil seal is determined by the shape of the sliding surface of the seal lip portion 2 that contacts the outer periphery of the shaft 5;
That is, it is known that it depends on the particle size and shape of the filler 12 exposed on the sliding surface.

[To Nakamura Lab; Japan Rubber Association Journal, 62°74-8.3 (198
Refer to 9) Generally, flat-shaped natural inorganic compound fine particles are used as the filler 12, but these inorganic compound fine particles have a large particle size distribution and a wide aspect ratio distribution. Therefore, in a sealing member l in which fine particles of an inorganic compound are dispersed in the rubber material 1) as a filler 12, the fine particles of an inorganic compound exposed on the IS moving surface of the seal lip portion 2 are does not have a uniform particle size and aspect ratio, so it has been extremely difficult to vulcanize and mold with good reproducibility the desired sealing performance.

As shown in FIG. 4, the step of manufacturing the sealing member l by injection molding is as follows: 1) + A batch of kneading the weighed rubber material 1) and a filler 12 made of fine particles of an inorganic compound in a batch. a kneading step, (2) a roll kneading step of cooling the kneaded material obtained in step (1) above, adding a vulcanizing agent and kneading it with a roll, (3) a step of kneading the kneaded material obtained in step (2) above. It consists of a step of cooling the kneaded material and extruding it with an extruder to obtain a band-shaped dough rubber, and (4) a molding step of putting the band-shaped dough rubber obtained in step +3 above into an injection molding machine and vulcanization molding. ing.

However, in the manufacturing process of the sealing member l as described above, manual labor is required in the roll kneading process of (2) above, and there is a large risk of workers getting caught in the rolls. , When putting the dough rubber manufactured in step (3) into the injection molding machine in the next step (4), the work of transporting and feeding the dough rubber is complicated,
Furthermore, in the steps (2) to (4), the rubber material l
Filler 1 in a chemically and physically stabilized state
The operation of kneading and blending 2 is carried out by skilled workers based on their experience and acumen.The conventional manufacturing process for sealing members requires a large number of skilled workers, and the work is dangerous. Furthermore, since steps (1) to (3) are long steps of about 100 minutes, there was a problem in that the manufacturing process needed to be simplified and shortened. .

The present invention solves the problems of the conventional methods as described above, and instead of the conventional filler consisting of fine particles of a natural inorganic compound, a micro-dispersed phase is used in a polymer that exhibits rubber-like elasticity at room temperature. Using a polymer that is solid at room temperature as a filler, fine particles of the polymer that is solid at room temperature are uniformly dispersed in the rubber-like elastic polymer, and this microdispersed phase is oriented under predetermined conditions. By doing so, it is possible to control the particle size, dispersion state, aspect ratio, etc. of the fine particles of the polymer that is the filler in the manufacturing process, and it is possible to control the manufacturing process from kneading to vulcanization molding in an integrated manner, making it possible to control the manufacturing process. It is an object of the present invention to provide a sealing member for an oil seal that can be greatly simplified and a method for manufacturing the same.

[Means to solve the problem]

In order to achieve the above object, the seal member for an oil seal of the present invention is a seal member for an oil seal that slides on the outer periphery of a rotating or reciprocating shaft to seal the oil side and the atmosphere side of the shaft. This sealing member for an oil seal has fine particles of a first polymer that is solid at room temperature oriented in a second polymer that is incompatible with the first polymer and exhibits rubber-like elasticity at room temperature. The method of manufacturing the sealing member for an oil seal according to the present invention includes means for uniformly dispersing the oil seal, and the method for producing the sealing member for an oil seal of the present invention includes: a means for sliding on the outer periphery of a rotating or reciprocating shaft to connect the oil side and the atmospheric side of the shaft; A method for producing a sealing member for an oil seal that seals, wherein a first polymer that is solid at room temperature and a second polymer that is incompatible with the first polymer and exhibits rubber-like elasticity at room temperature are both polymers. to prepare a kneaded product in which fine particles of the first polymer are uniformly dispersed in a second polymer to form a microdispersed phase, and then a vulcanizing agent is added to this kneaded product. The vulcanizing agent is added and further kneaded, and then this vulcanizing agent-added kneaded product is placed in a mold.
The method includes means for applying shear stress near the softening point temperature of the first polymer to vulcanize and mold fine particles of the first polymer uniformly dispersed in the @2 polymer in an oriented state. .

[Effect]

By adopting the above means, the present invention provides a sealing member in which fine particles of the first polymer, which is solid at room temperature, have a substantially uniform particle size in the second polymer, which is a base material and exhibits rubber-like elasticity at room temperature. , and the fine particles of the first polymer that are dispersed in an oriented state and exposed on the sliding surface of the sealing member have a predetermined sealing function, and when manufacturing this sealing member, The particle size, dispersion state, and orientation state of the fine particles of the first polymer in the second polymer can be arbitrarily adjusted by adjusting the temperature, time, shear stress, etc. during kneading and molding in the manufacturing process. This means that it is possible to control and provide desired sealing performance.

〔Example〕

Embodiments of the present invention shown in the drawings will be described below.

FIG. 1 shows the manufacturing process of the sealing member for an oil seal of the present invention. First, a predetermined amount of a first polymer A that is solid at room temperature and a second polymer that exhibits rubber-like elasticity at room temperature are prepared. If! in a state in which a predetermined amount of B and Put it in the kneading machine.

Then, the first and second polymers A1B are heated to a temperature above the melting point temperature of both polymers A and B, and then
By the first kneading step of kneading with am, a kneaded product is prepared in which fine particles of the first polymer A form a microdispersed phase in which the fine particles of the first polymer A are uniformly dispersed in the second polymer B.

Next, after the temperature of the kneaded product obtained by U4i1 in this first kneading step is lowered to a predetermined temperature, a vulcanizing agent is added and kneaded in a second kneading step.

Furthermore, the vulcanizing agent kneaded product obtained by adding and kneading this vulcanizing agent is put into a molding machine such as a press molding machine or an injection molding machine, and sheared while being heated to around the softening point temperature of the first polymer A. Stress is applied to orient the fine particles of the first polymer A, which is a microdispersed phase dispersed in the second polymer B, and vulcanization molding is performed in this state.

The time from the first kneading step to before the vulcanization molding step is about 20 to 30 minutes.

The first polymer A that is solid at room temperature and the second polymer B that exhibits rubber-like elasticity at room temperature may each be composed of a plurality of polymers.

As an example of the combination of the first polymer 8 and the second polymer B, polystyrene (P
S) and polyethyl acrylate (PEA) as the second polymer B, polypropylene (PP) as the first polymer A and ethylene-propylene rubber (EPDM) as the second polymer B, as the first polymer A polystyrene (PS) and polydimethylsiloxane (PDMS) as the second polymer B, polyethylene (PE) as the first polymer = A and second polymer B
isoprene rubber (IR) or butadiene rubber (BR) as first polymer A, polyethylene (P
E) and ethylene-propylene rubber (EPDM) as the second polymer B, a mixture of fluororubber and polystyrene as the first polymer A, and the second polymer B
Typical examples include polyethylene (PE).

In addition, the mixing ratio of the first polymer 8 and the second polymer B is such that the first polymer A is in the second polymer B.
Any ratio may be used as long as the fine particles are dispersed and blended in a phase-separated state to form a micro-dispersed phase, but the ratio of the second polymer B to the total amount of both polymers A and B is 60% by weight. or more, preferably 70! I! The amount is at least 70 parts by weight, more preferably 70 to 85 parts by weight.

The kneading temperature and shear stress in the first kneading step are determined based on the intrinsic viscosity of each of the first polymer A and the second polymer B in their molten state, the target particle size of the first polymer A fine particles, etc. Appropriate conditions can be selected taking into consideration.

After the first kneading step, the temperature of the kneaded product is lowered to a predetermined temperature before adding the vulcanizing agent, and the temperature at this time is such that the state of dispersion of the fine particles in the first polymer in the kneaded product is stable. The temperature is maintained at a temperature at which the vulcanizing agent can be kneaded and blended, and the method of lowering the temperature is to lower the temperature in a short period of time rather than gradually lowering the temperature to prevent agglomeration of the fine particles of the first polymer A. is preferred.

Therefore, the kneading temperature and shear stress in the second kneading step after adding the vulcanizing agent are determined as appropriate within the range where the vulcanizing agent is kneaded and the fine particles of the first polymer A are maintained in a dispersed state. Conditions can be selected.

In the vulcanization molding step, shear stress is applied to the vulcanizing agent-added kneaded product while it is heated to around the softening point temperature of the first polymer A, and the magnitude of the shear stress at this time is equal to It is sufficient that the shear stress has a size that orients the fine particles of the first polymer A in the polymer B of No. 2, and an appropriate size of shear stress should be selected depending on the desired degree of orientation and taking into account temperature, etc. As a specific means for applying shear stress, orientation can also be achieved by using a two-wheel or axle extrusion molding machine, and applying extrusion pressure when loading the vulcanizing agent InW into the molding machine. Alternatively, the portion within the molding machine that forms the sliding surface of the seal lip portion 2 may be made rotatable, and the shearing stress may be applied by the rotational force.

In the sealing member for an oil seal according to the present invention manufactured by the above steps, in the first kneading step, the second polymer B, which is a base material and exhibits rubber-like elasticity at room temperature, is mixed with a polymer that is solid at room temperature. As shown in Fig. 2+al, the fine particles of Polymer A of No. 1 are uniformly dispersed as a microdispersed phase with a substantially uniform particle size, and this state is maintained in the next second kneading step, and then, In the final vulcanization molding step, shear stress that deforms and orients the fine particles of the first polymer A acts, causing the fine particles of the first polymer A to form flat, uniform shapes, as shown in Figure 2. In this state, the sliding surface of the obtained sealing member l according to the present invention has fine particles in the first polymer in the second polymer B. They are uniformly dispersed in a flatly deformed and oriented state, and have a predetermined and stable sealing function when sliding on the outer periphery of the shaft 5.

In addition, in the method of manufacturing a sealing member for an oil seal of the present invention, compared to a conventional sealing member for an oil seal containing fine particles of a natural inorganic compound as a filler, the sealing member as a sealing member for an oil seal is The particle size, dispersion state, and aspect ratio of the fine particles of the first polymer A, which is a filler that affects performance, are determined by the temperature in the kneading process, the magnitude of shear stress, the kneading time, and the magnitude of shear stress in the vulcanization molding process. Since it can be reliably controlled by changing the factors such as the experience of experienced workers, there are no uncertain factors such as kettle, etc., and it is possible to stably supply sealing members with constant quality and stable sealing performance. It becomes possible.

Furthermore, the manufacturing process of the sealing member for oil seals of the present invention does not require operations such as manually transporting the roll-shaped kneaded material or carrying it into the molding machine, and wasteful time in the process can be omitted. Not only can it be simplified, but the safety of the process can be improved as there is no risk of the makikomya being caught between the rollers during roll kneading, and the process can be manufactured using an integrated production line from kneading to vulcanization molding, so it is possible to introduce robots into the manufacturing process. It is easy to unattend the manufacturing process, and the process can be greatly simplified. Furthermore, the time from the first kneading process to the vulcanization molding process is about 20 to 30 minutes, compared to conventional manufacturing. It is possible to significantly shorten the process compared to other processes.

Furthermore, by using, for example, a mixture of two types of resin materials, ie, a resin material with good low-temperature properties and a resin material with good wear resistance properties, as the first polymer A, a sealing member excellent in both properties can be obtained. It also becomes possible.

The present invention will be explained in more detail below using experimental examples.

Experimental example As the first polymer A, the average molecular weight? , 75X1
0' monodispersed polystyrene (melting point: about 200°C, softening point: about 180°C) (manufactured by Toso Corporation) and 20 parts by weight of the second polymer B, a polystyrene with an average molecular fit of 1.0XIO'' without crosslinking sites was prepared. Ethyl acrylate (melting point approx. 1) 0℃)
(manufactured by Nippon Metatron Co., Ltd.) and all 80 weights were melted at 200° C. under a nitrogen atmosphere, put into an internal mixer, and kneaded at 4 Q rpm for about 10 minutes at a kneading temperature of 200° C. (The total amount of the first and second polymers was 80% of the capacity of the internal mixer.) The particle size of the fine particles added to the first polymer in the obtained kneaded product was determined to be 8 to 20 μm by observation with an optical microscope. It was confirmed that the fine particles of the first polymer A had a microphase-separated structure in the second polymer B in an incompatible state.

Next, after the temperature of the kneaded product was lowered to 100°C, 0.3 parts by weight of sulfur, 0.5 parts by weight of sodium stearate, and 0 parts by weight of potassium stearate were added to the kneaded product as a vulcanizing agent and a vulcanization accelerator. .5 overlapping parts were added and kneaded at 100°C for 10 minutes.

Next, the above-mentioned vulcanizing agent-added kneaded product is put into a twin-screw or J4i-shaft extrusion molding machine, and by this twin-screw or axle-shaft extrusion molding machine, the kneaded product with the addition of a vulcanizing agent is produced at a rate of 0.7 kg/m or more (in terms of torque value), preferably 0.7 kg/m or more. After applying a shear stress of ~1.2 kg/m,
Vulcanization molding was performed at 180°C for 5 minutes.

The cross section and sliding surface of the seal lip portion 2 of the oil seal sealing member 1, which is the vulcanized product obtained above, are
As shown in Figure (color), fine particles of the first polymer A, which is solid at room temperature, were uniformly dispersed in an oriented state in the second polymer B, which exhibits rubber-like elasticity at room temperature.

〔Effect of the invention〕

Since the present invention is configured as described above, the sliding surface of the seal member of the present invention contains a filler, compared to a conventional seal member for an oil seal containing fine particles of a natural inorganic compound as a filler. Since the fine particles of the first polymer are dispersed with a substantially uniform particle size and in an oriented state, a stable seal 4! The particle size, dispersion state, and aspect ratio of the first polymer fine particles, which have S1 properties and are the filler that influences the sealing performance of this oil seal sealing member, are controlled by the temperature and shear stress in the kneading process. It can be reliably controlled by changing the size, kneading time, and shear stress in the vulcanization process, so there are no uncertainties such as the experience of skilled workers, and a stable seal with constant quality can be achieved. It is possible to stably supply a sealing member with high performance, and furthermore, there is no need to manually transport the roll-shaped a mixture or carry it into the molding machine, which reduces the process time. Wasted time can be omitted and the process can be simplified, and the safety of the process can be improved since there is no danger of the makikomya being caught by the rollers during roll kneading.

In addition, since it can be manufactured on an integrated production line from kneading to vulcanization molding, the manufacturing process can be easily automated by introducing robots/ ), making it possible to significantly simplify the process. It has excellent effects such as being able to significantly shorten the manufacturing process compared to the manufacturing process.

[Brief explanation of the drawing]

FIG. 1 is a process explanatory diagram showing the manufacturing process of the sealing member for an oil seal of the present invention, FIG. The figure is a diagram illustrating the structure of the -IW oil seal, and FIG. 4 is a process explanatory diagram illustrating the manufacturing process of a conventional sealing member for an oil seal. 1... Seal member 2... Seal lip portion 3... Spring 4... Metal ring 5... Shaft 6...・Housing A...ml Polymer B...Second polymer 1)...Rubber material 12...Filler (inorganic compound) Patent application Figure 1, Figure 6, Figure 2 (b) Tsutomu Wako Magakata - Procedural amendment (bladder ■, case description, 1999 patent application No. 12)
6488 No. 2, Title of the invention Seal member for oil seals and method for manufacturing the same 3, Relationship with Amendr Hanyu Patent applicant. Address 1-12-15 Shiba Daimon, Minato-ku, Tokyo Name N.O.K. Research Institute of Technology 4, Agent ■1021 Kujira 262-4761
)Address: 8-13-5 Kudanminami 3-chome, Chiyoda-ku, Tokyo Date of amendment order Voluntary 7 Contents of amendment (1) The scope of claims in the specification
Correct. (2) In the same book, page 7, line 3, “uniformly dispersed in the state” [
Minute ti with 4 pieces! t, , J. (3) In the second line of the same page of the same book, "uniformly inside" is corrected to "inside." (4) In the second line of the same page of the same book, "uniformly inside" is corrected to "inside." (5) "Mixture of fluorine rubber and polystyrene" in the first line of page 1 of the same book is corrected to "polystyrene or polyethylene." (6) “Polyethylene (PE)” in the second line of the same page of the same book
Correct J to "fluororubber". (7) In the same book, page 16, line 6, "without a crosslinking site" is amended to "having a crosslinking site". (8) Add r (PA401)J after "polyethyl acrylate" in lines 2 to 7 of the same page of the same book. (9) In the same book, page 17, lines 6 to 8, ro, 7,
g/m or more ~ 0.7 to 1.2 kg/ml at "revolutions 14
Orpm corrects the total energy to 300 MJ/m'J. 8. List of attached documents fl) Attached sheet......1 attached sheet Claims (1) Sliding on the outer periphery of the rotating or reciprocating shaft (5), the oil side of the shaft (5) and the atmosphere A sealing member (1) for an oil seal sealing the sides, the sealing member (1) for an oil seal is made of a first polymer (A) that is solid at room temperature.
) are dispersed in an oriented state in a second polymer (B) that is incompatible with the first polymer (A) and exhibits rubber-like elasticity at room temperature. Seal material for use. (2) A method for manufacturing an oil seal seal member (1) that slides on the outer periphery of a rotating or reciprocating shaft (5) to seal the oil side and the atmosphere side of the shaft (5), the method comprising: A solid first polymer (A);
) and an incompatible second polymer (B) that exhibits rubber-like elasticity at room temperature are kneaded at a temperature higher than the melting point temperature of both polymers (A) and (B), and the fine particles of the first polymer (A>) are kneaded. A kneaded product is prepared by dispersing in the second polymer (B) to form a micro-dispersed phase, then a vulcanizing agent is added to this kneaded product and further kneaded, and then this vulcanizing agent addition kneading Shearing stress is applied to the object in a mold at a temperature near the softening point of the first polymer (A) to orient the fine particles of the first polymer (A) dispersed in the second polymer (B). A method for manufacturing a sealing member for an oil seal, characterized by vulcanization molding in a state of

Claims (2)

[Claims] (1) An oil seal seal member (1) that slides on the outer periphery of a rotating or reciprocating shaft (5) to seal the oil side and the atmosphere side of the shaft (5), the oil seal seal Member (1) includes fine particles of a first polymer (A) that is solid at room temperature in a second polymer (B) that is incompatible with the first polymer (A) and exhibits rubber-like elasticity at room temperature. A seal member for an oil seal, characterized in that the seal member is uniformly dispersed in an oriented state. (2) A method for manufacturing an oil seal sealing member (1) that slides on the outer periphery of a rotating or reciprocating shaft (5) to seal the oil side and the atmosphere side of the shaft (5), the method comprising: A first polymer (A) that is solid and a second polymer (B) that is incompatible with the first polymer (A) and exhibits rubber-like elasticity at room temperature.
) are kneaded at a temperature higher than the melting point temperature of both polymers (A) and (B), and the fine particles of the first polymer (A) are uniformly dispersed in the second polymer (B) to form a microdispersed phase. Next, a vulcanizing agent is added to this kneaded material and further kneaded, and then this vulcanizing agent-added kneaded material is placed in a mold to soften the first polymer (A). An oil seal characterized in that vulcanization is performed in a state in which fine particles of the first polymer (A) are oriented and uniformly dispersed in the second polymer (B) by applying shear stress near a point temperature. A method for manufacturing a seal member for use.