JPS59223797A - Composition for stabilization of lubricant film on friction material - Google Patents

Abstract

PURPOSE:To provide the titled compsn. consisting of a mixt. of an amorphous ethylene copolymer, a synthetic oil, a solid lubricant and a vulcanizing agent and forming a high quality lubricant film on friction material for motor with electromagnetic clutch brake. CONSTITUTION:The compsn. consists of (A) amorphous ethylene/alpha-olefin copolymer having an MW of 5X10<4> or higher, e.g. ethylene/propylene copolymer with an ethylene content of about 20-85mol%, and/or amorphous ethylene/alpha-olefin/ non-conjugated polyene copolymer, e.g. ethylene/propylene/dicyclopentadiene copolymer with an ethylene content of about 20-85mol%, (B) synthetic oil (having a kinematic viscosity of about 100 cSt or lower at 40 deg.C), (C) solid lubricant, e.g. graphite or molybudenum, and (D) at least one each of vulcanizing agent, e.g. cumene hydroperoxide, heat-polymerizable resin, e.g. epoxy resin, and drying oil.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to clutch linings for motors with electromagnetic clutches and brakes, such as those used to drive industrial sewing machines;
The present invention relates to a lubricating film stabilizing composition formed on the friction surface of a friction material used in brake linings.

Conventional configuration and its problems Figure 1 shows the main parts of a motor with an electromagnetic clutch/brake.At one end of the rotating shaft 1 of the drive motor, there is a Kura-Sochi disk 2, which is one of the clutch structures. A flywheel 3, which is an inertial body with a , Brakes tz
t, and also supports the flange shaft 11 via a bearing 8. This clutch shaft 11 has a pulley 9 for taking out an output at one end, and a sliding shaft portion (spline) 10 is formed at the other end. A clutch ring 14 holding a clutch lining (friction material) 13 and a brake ring 15 are supported so as to be movable in the axial direction on a sliding shaft 10 (relative movement in the rotational direction is not possible), and both are supported by an O ring 16 and a coupling 17. are connected.

Next, the operation of the electromagnetic clutch/brake will be explained.

The rotating shaft 1 is continuously rotating, and a flywheel 3 fixed to the end of the shaft is in a state where rotational energy is stored. Therefore, when the clutch winding 6a is energized, the electromagnetic force is extracted to the pulley 9 through the sliding shaft 10 and the clutch shaft 11. When stopping the brake winding 6a, electromagnetic force 6b is generated and the brake ring 15 is attracted to the brake ring 11, and the brake lining (friction material)
A braking force is generated between the sliding shaft 10 and a brake ring fixed to the end bracket 4 through the entire sliding shaft 10 and the clutch shaft 11 via the clutch shaft 13, and braking is performed.

Motors with electromagnetic clutches and brakes having the above configuration are widely used to drive industrial sewing machines that typically start and stop frequently. Rotational speeds up to 5000 rpm are used. In this case, as with ordinary friction materials for clutches and brakes, the noise generated during clutch and brake operation and the unpleasant odor from the friction surface are disliked. Furthermore, as a motor with an electromagnetic clutch/brake for driving a sewing machine, it can be operated approximately 10,000 times a day. Since a brake action is performed, a long-life friction material is required.

In order to satisfy the above requirements, as a friction material for a motor with an electromagnetic clutch/brake, for example, US Pat.
Cork is used, as known from No. 4472, and its counterpart material is usually highly ground carbon steel.

The above-mentioned cork is generally made by mixing cork particles obtained by crushing cork bark with a particle binder such as phenol resin, polyurethane resin, urea resin, or polyvinyl acetate resin, and then heating and compressing the mixture to produce pressed cork or fired cork. To tell.

The reason why cork is used as a friction material is that although cork is a natural plant product, it is free from oils, fats, and organic acids.
It is chemically stable against soaps, alkalis, and salts, and does not generate any odor and has sufficient heat resistance as a friction material for electromagnetic clutches and brakes where the friction surface temperature is up to about 80°C. This is because that. Furthermore, approximately 26 per d
It is soft and has a large damping property tan δ derived from the structure of about 10,000 minute air-filled cells, and has a large porosity, which produces a soft contact sound during clutch/brake operation, and is also a factor in friction characteristics such as the friction coefficient. This is because, due to the above-mentioned properties, it has the advantage of being a material that is less likely to squeal during clutch/brake operation.

On the other hand, the frictional characteristics of the cork generally tend to change due to external factors such as temperature and sliding speed unless a lubricating film is present on the friction surface, resulting in unstable clutch/brake operation. Furthermore, since dry cork itself has a high coefficient of friction, the coefficient of static friction is higher than the coefficient of kinetic friction, just like other materials with high friction coefficients. In such cases, stick-slip phenomena are likely to occur in the low speed range,
In this state, the rate of change in the coefficient of friction due to temperature is large, and squealing noise is likely to occur during clutch/brake operation. Furthermore, since cork itself has poor heat dissipation properties, frictional heat tends to accumulate on the friction surface, and as a result, the mechanical strength of the cork near the friction surface becomes smaller than the adhesive force with the other material, and a part of the cork Abnormal friction and wear may occur, such as transfer to the mating material or a portion of the material falling off. This abnormal wear phenomenon becomes noticeable especially when a clutch/brake operation is performed at high speed F, accompanied by a squealing noise.

To prevent the problems caused by the frictional characteristics of cork as described above and utilize the advantages of cork, for example, cork may be impregnated with grease as disclosed in U.S. Pat. No. 3,777.864, or There is also a friction material made of cork impregnated with lubricating oil. However, because cork is used as a waterproofing material and cork stopper, due to the resinous substance and uniform cell structure of cork itself, cork is used as a waterproofing material and cork stopper. Since it is difficult to directly infiltrate lubricating oil, it is actually infiltrated between the cork particles of pressed cork or fired cork.Furthermore, a friction material with a structure in which cork is impregnated with a portion of the base oil of grease. The reason why this type of friction material is more effective against abnormal wear phenomena and squealing noise during clutch/brake operation than when cork is used as a part of the material is that it provides lubrication on the friction surface. This is because a film is formed, which can improve problems caused by the frictional properties of cork.

Generally, when lubricating oil or grease exists on a friction surface and functions as a lubricating film, the coefficient of friction decreases. Since it is easy to secure a sufficient friction coefficient as a friction material for clutch/brake operation, it is also possible to secure a sufficient friction coefficient at a temperature of 2.
This is because the lubricating film can maintain a significantly stable friction coefficient of 8 (I) even against external factors such as surface pressure and sliding speed.Of course, lubricating oil or grease can lubricate the friction surface. If the film loses its function, it will not only cause squealing noise during clutch/brake operation, but also accelerate wear of the friction material, leading to the end of its service life.

Therefore, we have responded to the need to extend the lifespan of friction materials, which is an issue in motors with electromagnetic clutches and brakes that use porous materials such as cork as friction layers, and to create friction materials that are less likely to generate squealing noises during clutch and brake operation. Therefore, it is important to have a means for the lubricating oil or grease to maintain its function as a lubricating film on friction surfaces for a long period of time.

Purpose of the Invention The present invention maintains the function of the lubricating film of the friction material for a motor with an electromagnetic clutch/brake, and performs a stable latch/brake operation over a long period of time. The purpose is to suppress the phenomenon of a decrease in transmitted torque during clutch/brake operation, which is a disadvantage.

Structure of the Invention The present invention stabilizes a lubricating film formed by lubricating oil or grease on the friction surface of a soft porous material such as pressed cork or fired cork used as a friction material for a motor with an electromagnetic clutch or brake. 1 selected from the compounds listed in a to d below.
Seed-! or a mixture of two or more. a molecular weight is 6
X 104 or more amorphous ethylene-α-olefin copolymer, amorphous ethylene-α-olefin-nonconjugated polyene copolymer, b synthetic oil, mineral oil, C solid lubricant, d vulcanizing agent, thermopolymerizable resin , is a dry surface. In addition, various additives known as lubricating oil additives may be appropriately used in the synthetic oil and mineral oil (b).

Description of Examples The amorphous ethylene-α-olefin copolymer referred to in the present invention is an amorphous copolymer of ethylene and α-olefin. Examples of Oa-olefin include propylene, butene-
1, hexene-1, and the like. Particularly preferred polymers are ethylene-propylene copolymer and ethylene-butene-1 copolymer. The ethylene content in the copolymer is between 20 and 86 moles, preferably between 30 and 80 moles. Further, the amorphous ethylene-a-olefin-nonconjugated polyene copolymer is a low unsaturated amorphous copolymer consisting of ethylene, α-olefin, and nonconjugated polyene.

Examples of α-olefins are propylene, butene-1,
Examples include hexene-1. % propylene and butene-1 are preferred. A non-conjugated polyene is a cyclic polyene containing two or more non-conjugated double bonds. It is an acyclic polyene, such as acyclic conjugated dienes such as hexadiene-1,4, hexadiene-1,6, hewotadie-7-1.6.2-methyl-pentadiene-1,4, and octatriene-1. , 4,7, etc., ethylidenenorbornene, synchlopentadiene, cyclooctacy, T-7-1,4, cyclooctadiene-1,5,
Cyclododecadiene 7-1,6, Cyclododecadiene-1
, 7, cycloheptadiene-1,4, cyclohexadiene-1,4, and cyclododecatriene-1,5,9. Among them, cyclic non-conjugated dienes are preferred;
Synchropentagene and ethylidene norbornene are particularly favorable. Particularly preferred amorphous ethylene-α-olefin nonconjugated polyene copolymers are ethylene-propylene dicyclopentadiene copolymer and ethylene-propylene-ethylidene norbornene copolymer. The ethylene content in the copolymer is 20 to 86 mol, preferably 30
~80 molar ratio, and the content of non-conjugated polyene is ~0.1~
The amount is 20 mol, preferably 0.1 to 16 mol.

In addition, the mineral oil or synthetic oil referred to in the present invention is generally used as a base oil for grease, etc., but in order to reduce the friction coefficient of the friction material to 0.5 or less, the kinematic viscosity at 40 ° C. Preferably, it is 100 cst or less.

Moreover, the vulcanizing agent referred to in the present invention refers to an organic peroxide represented by the general formula R-00H. However, R may be an aliphatic or cycloaliphatic residue, or an aromatic residue, and these may have a substituent.

Specific examples include bromo-1-butyl hydroperoxide, cumene hydroperoxide, and t-amyl hydroperoxide.

It also includes the case where a solution of a transition metal salt of an organic carboxylic acid having 7 or less carbon atoms in a polar organic solvent is used in combination with a compound having a carbon-carbon double bond as a vulcanization accelerator. Furthermore, as an alternative to the vulcanizing agent, epoxy resin, phenol resin,
One or more thermopolymerizable resins selected from the group consisting of acrylic resins, and even a drying oil may be used. These vulcanizing agents or thermopolymerizable resins are preferably liquid and crosslinkable at low temperatures.

In addition, the solid lubricants referred to in the present invention include graphite, molybdenum disulfide, tungsten disulfide, metal iodides such as nickel iodide, carbon fluoride, etc., and one or more of these are used as appropriate. be done.

In the present invention, in addition to the above, organic solvents such as methanol, ethanol, ethylene glycol, octane, hexane, toluene, xylene, acetone, methyl ethyl ketone, methyl isobutyl ketone, and dimethyl acetamide can also be used in combination.

The above-mentioned lubricating film function stabilizer consisting of the amorphous copolymer, mineral oil, synthetic oil, vulcanizing agent or thermopolymerizable resin composition, drying oil, solid lubricant, and diluent can be easily mixed uniformly. can be manufactured.

In particular, the amorphous ethylene-a-olefin copolymer or amorphous ethylene-a-olefin-nonconjugated polyene copolymer used in the present invention has a molecular weight of 5.times.10 or more. This has a higher shear stability than, for example, polyisobutylene with a molecular weight of 1 to 1.5 x 104 and polymethacrylate (methacrylic acid ester polymer) with a molecular weight of 5 x 10 to 2.0 x 10, which are generally used as lubricating oil viscosity index improvers. It has excellent thermal stability.

Next, details of the present invention will be specifically explained while comparing with comparative examples. The friction properties of the friction material used in the following explanation are based on JI
Compliant with S-D4411, the mating material has a surface roughness of 3.
It is a carbon steel plate ground to S, and the sliding speed is 2 m /
sec, the surface pressure of friction 4 is □1, 8kg1
/aj condition.

(Comparative Example) Figure 2 shows the relationship between friction surface temperature and dynamic friction coefficient. In the figure, A is pressed cork obtained by adding 20 parts by weight of a polyurethane resin as a binder to 100 parts by weight of cork particles of 14 to 35 mesh, and heating and compressing the material to an apparent density of about 0.6 GLCR.

Bid A is impregnated with a lubricating oil with a kinematic viscosity of 85 cst at 40°C, and C has a kinematic viscosity of 465 cs at 40"C.
The friction material is impregnated with a lubricating oil of 0.0 The characteristic curve in Figure 2A shows that when pressed cork, fired cork, or other cork is used as it is as a friction material, the coefficient of dynamic friction changes with temperature. Larger, this makes the clutch
It is obvious that squealing noise is likely to occur during brake operation. In this case, although the value of the dynamic friction coefficient varies somewhat depending on the type and amount of the binder in the cork particles, it remains the same with respect to changes due to temperature. Therefore, U.S. Patent Nos. 3 and 7
77.

We will focus on B and C, which correspond to friction materials made of cork impregnated with lubricating oil, as also known as No. 86. When a lubricating film is formed on the friction surface by the lubricating oil impregnated into cork as in this case, the rate of change in the coefficient of dynamic friction due to temperature becomes extremely stable. Further, as inferred from the value of the dynamic friction coefficient, it is also possible to adjust the friction material to have a desired friction coefficient by appropriately selecting the base oil viscosity of the lubricating oil or grease that forms the lubricating film. In the case of C, since the coefficient of dynamic friction is high, it can be inferred that squealing noise is likely to occur during clutch/brake operation.

FIG. 3 is a characteristic diagram showing changes in the dynamic friction coefficient and the amount of friction with respect to the friction distance. Table 1 shows the structure of the friction material shown in FIG.

In Table 1 and FIG. 3, the dynamic friction coefficients of friction materials C, D, and H exhibit a maximum change with respect to the friction distance. In this phenomenon, the coefficient of dynamic friction increases as the lubricating oil forming a lubricating film on the friction surface is consumed, and as a result, some of the cork particles near the friction surface fall off. Then, the lubricating oil present inside the friction material, that is, between the cork particles, flows out from that part onto the friction surface and forms a lubricating film, so that the coefficient of dynamic friction decreases again. However, since it is not possible to secure a sufficient lubricant film between cork particles near the friction surface due to the effects of temperature, surface pressure, etc., the coefficient of dynamic friction remains highly stable.
The brakes tend to squeal when operating the brakes. Also,
When such a coefficient of dynamic friction shows a maximum, an abnormal friction state occurs, which has the drawback of extremely shortening the life of the friction material. Even if the oil content of friction material C is increased as shown in H, or even if grease is applied to the friction surface, the maximum point of change in the coefficient of dynamic friction and the corresponding abnormal wear phenomenon will be slightly shifted to the long distance side. Only.

As mentioned above, even if lubricating oil is impregnated between cork particles and a lubricating film is formed on the friction surface, or grease is applied to supplement the amount of lubricating oil that forms the lubricating film, it will not last for a long time. It is insufficient as a friction material for stable clutch/brake operation. This is because the space between the cork particles near the friction surface is narrowed by surface pressure or frictional heat, so the lubricating oil present inside the friction material does not function effectively on the friction surface.

(Example) Next, an example of the friction material lubricating film stabilizing composition according to the present invention will be described.

However, friction material F contains 15 parts by weight of an amorphous ethylene-propylene copolymer with a molecular weight of about 7 x 10, 0.5 parts by weight of a mixture of cumene hydroxyperoxide and ethylene glycol dimethacrylate, 10 parts by weight of molybdenum disulfide, and 40°C. Alkylbenzene 8o with a kinematic viscosity of 28cst
A friction material lubricating film stabilizing composition consisting of parts by weight was applied to the friction surface of friction material C shown in Table 1. Further, G is 15 parts by weight of an amorphous ethylene-propylene-dicyclopentadiene copolymer with a molecular weight of about 7 x 104, 8 parts by weight of phenolic resin, 10 parts by weight of molybdenum disulfide, and 40 parts by weight of molybdenum disulfide.
A friction material lubricant film stabilizing composition comprising 80 parts by weight of alkylbenzene having a kinematic viscosity of 28 cst at °C was similarly applied to the friction surface of friction material C.Friction material E is a friction material lubricant film according to the present invention described above. As a comparative example of the stabilizing composition, grease was applied to the friction surface with a friction amount of C. However, the grease was composed of 15 parts by weight of polyisobutylene having a molecular weight of about 5 x 103, 10 parts by weight of molybdenum disulfide, 9.5 parts by weight of lithium stearate, and 8Q parts by weight of alkylbenzene having a kinematic viscosity of 28 cst at 40'C.

In both F and G in Figure 3, the fluctuation of the dynamic friction coefficient is extremely small compared to the amount of friction ~G, and the value is also at the stage of C when the friction distance is still small, that is, when the lubricating oil forms a lubricating film on the friction surface. It is equivalent to the value of the coefficient of kinetic friction when the function is fully fulfilled. This clearly shows that the friction material lubricating film stabilizing composition according to the present invention does not inhibit the lubricating film function of the lubricating oil in any way, and moreover works to stabilize that function over a long period of time. Incidentally, in the case of friction material E shown as a comparative example, although it has a similar structure to friction materials F and G, the above-mentioned effects that are clearly observed in F and G are not realized.

Next, the case where the above-mentioned friction material F (example) and friction material H (comparative example) are attached to the motor with an electromagnetic clutch and brake shown in FIG. 1 will be described.

FIG. 4 is a characteristic diagram showing the number of clutch/brake operations, wear of the friction material, and changes in transmitted torque when clutch/brake operations are performed every 1.5 SeC. As described above, according to the present invention, the life of the friction material is more than doubled, and the transmission torque is also doubled.
It can be improved by 0% or more.

FIG. 6 is a characteristic diagram showing the relationship between the transmission torque and the same structure as the friction material F using amorphous ethylene-propylene copolymers with different molecular weights. As described above, when the molecular weight of the amorphous copolymer is 104 or more, the transmission torque is significantly improved.

As a comparative example, a sufficient improvement in transmission torque was not observed when polyisobutylene having a molecular weight of 10,000 to 15,000 and polymethacrylate having a molecular weight of 6,000 to 20,000 were substituted with an amorphous copolymer.

, Effects of the Invention As described above, a friction material lubricant mainly composed of an amorphous ethylene α-olefin copolymer having a molecular weight of 6×10 4 or more or an amorphous ethylene-α-olefin-nonconjugated polyene copolymer according to the present invention. The use of membrane function stabilizing compositions enables stable clutch and brake operation over a long period of time.

[Brief explanation of drawings]

Figure 1 is a sectional view showing the configuration of the main parts of a motor with an electromagnetic clutch/brake, Figure 2 is a characteristic diagram showing the relationship between friction surface temperature and dynamic friction coefficient, and Figure 3 is a diagram showing comparative examples C, D, E and the present invention. A characteristic diagram showing the coefficient of dynamic friction and wear versus friction distance for Invention Examples F and G. Figure 4 shows the friction materials of Comparative Example E and Invention Example F installed in the motor with electromagnetic clutch and brake shown in Figure 1. FIG. 5 is a characteristic diagram showing the relationship between the number of clutch/brake operations, friction, and transmitted torque in each case. FIG. 5 is a characteristic diagram showing the relationship between the molecular weight of an amorphous copolymer and transmitted torque. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 20 40 60 110 10o 120 Friction surface temperature, b Figure 3 4 Kashi distance K? 7L Figure 4 Tarana flake operation number xto4

Claims (1)

[Claims] a amorphous ethylene-α-olefin copolymer or amorphous ethylene-a-olefin non-conjugated polyene copolymer with a molecular weight of 5 x 10 or more, b synthetic oil, C solid lubricant, d
Consisting of a vulcanizing agent, a thermopolymerizable resin, and a drying oil, the above a =
A friction material lubricating film stabilizing composition comprising one or a mixture of two or more selected from each group d.