JP2006002157A - Lubricating oil and lubricating grease for torque limiter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lubricating oil and a lubricating grease for a torque limiter in which variation in torque is small even under a high-temperature/high-humidity environment and development of chatter is suppressed by controlling metal to metal contact by the deficiency of an oil film to enable prolongation of service life of bearings, and which is excellent in resistance to chemical attack. <P>SOLUTION: The lubricating oil comprises a base oil composed of a synthesized saturated hydrocarbon oil having a kinematic viscosity at 40°C of 500-1,200 mm<SP>2</SP>/s and an emulsifier. The lubricating grease comprises the base oil, a thickening agent and an emulsifier. The emulsifier comprises a sulfonic acid metal salt dissolved in a solvent which does not cause chemical attack. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a lubricating oil and a lubricating grease used in a torque limiter used in an office machine or the like without being affected by a high-temperature and high-humidity environment that is severely lubricated and for stabilizing the generated torque and extending the bearing life. About.

There are torque limiters that use the radial binding force of the spring against the inner ring, and those that generate friction by pushing the friction plate against the friction plate in the thrust direction with the spring. Torque is generated. Many prior arts are known for the torque limiter (for example, Patent Documents 1 to 4).
Lubricating oil and lubricating grease are used to prevent the inner ring and spring or friction plate of the torque limiter, wear between the friction plate and the friction plate, abnormal heat generation, seizure noise, and the like. Further, the inner ring of the torque limiter is made of a metal sintered material, and has a lubricating mechanism that is used by impregnating lubricating oil.
Conventionally, as a lubricating oil and lubricating grease for torque limiters, mineral oils, aromatic compounds, esters, etc. are used as base oils and various additives such as antiwear agents are added depending on the application. Yes. The performance required for the torque limiter is to secure and maintain an oil film over a long period of time, and the performance of the torque limiter depends on how the metal contact can be suppressed and the friction coefficient can be stabilized. In particular, a torque limiter used in a paper feeding device such as a copying machine or a printer or a tension mechanism such as a ribbon or sheet is required to have a lubricant that is extremely small in torque fluctuation and does not generate metal contact noise.

Further, office machines such as copying machines using torque limiters are required to be usable without problems in various environments because of different usage environments. In particular, there is a demand for a lubricating oil that has extremely little torque fluctuation and does not generate metal contact noise in a high-temperature and high-humidity environment (for example, assuming 40 ° C. and a relative humidity of about RH 90%) where oil film formation is difficult. .
In addition, the peripheral parts of the torque limiter are made of resin such as polycarbonate resin or ABS resin, which has good processability, and the resin material is cracked by contact with oil or its vapor caused by leakage of lubricating oil used in the torque limiter. Cracks and surface roughness occur, and so-called chemical attack may occur. For example, a lubricating oil or the like using an ester or an aromatic compound as a base oil is known as a lubricating oil that has a high oil film forming ability and satisfies the torque performance required for a torque limiter. Lubricating oils mainly composed of base oils having aromatic rings or polar groups are likely to cause chemical attack, and ester base oils are prone to hydrolysis at high temperatures and high humidity.
In order to suppress chemical attack resistance, a rust preventive oil in which a rust preventive agent and an antioxidant are blended with a base oil is known. The base oil contains a polyolefin oil, and the anticorrosive oil contains the rust preventive oil. The rusting agent is at least one metal salt selected from a metal salt of a sulfonic acid and a metal salt of a monocarboxylic acid, and the antioxidant is a phenolic antioxidant (Patent Document 5).
Also, the base oil is synthesized as a lubricating oil and lubricating grease for torque limiters that have a small torque fluctuation and that can extend the service life of the torque limiter by suppressing metal contact due to oil film breakage. Torque, which is a saturated hydrocarbon compound and contains 1 to 8% by weight of at least one phosphoric ester selected from aliphatic phosphates and phosphites with respect to the total amount of lubricating oil A limiter impregnated bearing lubricating oil or lubricating grease is known (Patent Document 6).

However, the paper feeding unit of the copying machine or printer is used as a paper separating mechanism component by using the torque generated by the torque limiter. In a high temperature and high humidity environment, the viscosity of the lubricating oil decreases and the oil film thickness decreases, and moisture in the air drops into the lubricating oil and enters the lubricating oil, causing water to intervene on the lubricating surface. Therefore, there is a problem that oil film breakage occurs at an early stage, causing chatter (torque abnormality) and reducing the paper feeding function. In particular, there is a problem that chatter is likely to occur in a high humidity environment near the dew point temperature.
JP-A-8-270675 JP-A-7-301248 JP-A-6-235447 Japanese Utility Model Publication No. 5-8062 JP 2002-348688 A JP 2002-249794 A

  The object of the present invention is that a torque limiter used in an office machine or the like has a small torque fluctuation even in a high temperature and high humidity environment, and can extend the life of the bearing by suppressing metal contact due to oil film breakage. An object of the present invention is to provide a lubricating oil and a lubricating grease for torque limiters that are excellent in chemical attack resistance.

The lubricating oil for torque limiter of the present invention is characterized in that an emulsifier is blended in a base oil composed of a synthetic saturated hydrocarbon oil having a kinematic viscosity at 40 ° C. of 500 to 1200 mm ² / s.
The lubricating grease for torque limiter of the present invention is characterized in that an emulsifier and a thickener are blended with a base oil composed of a synthetic saturated hydrocarbon oil having a kinematic viscosity at 40 ° C. of 500 to 1200 mm ² / s.
The emulsifier used in the lubricating oil or lubricating grease for torque limiters is a sulfonic acid metal salt, and is a solution dissolved in a solvent that does not cause chemical attack.

The lubricating oil or lubricating grease for the torque limiter of the present invention uses a synthetic saturated hydrocarbon oil having a kinematic viscosity of 500 to 1200 mm ² / s as a base oil and a sulfonic acid metal salt as an emulsifier, so that water droplets enter the lubricant. Can be made into ultrafine water droplets with an emulsifier, and the oil film breakage can be suppressed due to the high viscosity. In addition, by using a synthetic saturated hydrocarbon oil and a sulfonic acid metal salt as main components, additives containing other polar components can be reduced, so that the chemical attack resistance to the resin material is excellent. For this reason, the torque limiter blended with the lubricating oil or lubricating grease for torque limiter of the present invention has little torque fluctuation even under high temperature and high humidity environment, and can obtain good torque stability.

  The base oil that can be used in the lubricating oil or lubricating grease of the present invention is a synthetic saturated hydrocarbon oil. Preferred are α-olefin oligomers, such as α-olefin polymers or copolymers of about 3 to 20 carbon atoms such as butene-1, isobutylene-1, α-octene, decene-1, etc. It is a normal temperature liquid oligomer. Examples of the copolymer include a copolymer of ethylene and the above α-olefin.

ここで、ｎは 4〜16 の整数、ｍは 1〜6 の整数である。

ここで、ｎは 1〜8 の整数、ｍは 1〜3 の整数、ｑは 1〜3 の整数、ｐはポリオレフィン油の粘度により異なる整数である。 Preferred base oils include poly-α-olefins represented by [Chemical Formula 1] or hydrides of ethylene-α-olefin copolymers represented by [Chemical Formula 2]. As the poly-α-olefin, an oligomer hydride of an α-olefin having 6 to 18 carbon atoms is preferably used. As the ethylene-α-olefin copolymer, a copolymer of ethylene and an α-olefin having 3 to 10 carbon atoms is used. Combined hydrides are preferably used.

Here, n is an integer of 4 to 16, and m is an integer of 1 to 6.

Here, n is an integer of 1 to 8, m is an integer of 1 to 3, q is an integer of 1 to 3, and p is an integer that varies depending on the viscosity of the polyolefin oil.

Polyolefin oil when used as a base oil in order to generate a stable torque in a torque limiter in a state where minute water droplets are emulsified in lubricating oil or lubricating grease in a high-humidity environment where dew condensation occurs is 40 kinematic viscosity at ℃ is 500~1200mm ² / s, preferably 700~900mm ² / s. When the kinematic viscosity is less than 500, oil film breakage is likely to occur in a high-temperature and high-humidity environment where fine water droplets are emulsified, and the initial torque reduction amount increases when it exceeds 1200 mm ² / s.
As the above base oil, poly-α-olefin is particularly preferably used. In order to obtain a predetermined base oil viscosity, two or more types of poly-α-olefins having different viscosities can be mixed and used alone. Is preferred.

  Since the above base oil has a high viscosity, the oil film forming ability is high. Therefore, the effect of suppressing the chatter of the torque limiter and the wear of the bearing is great, and the life of the bearing can be extended. Since these base oils are excellent in chemical attack resistance, no chemical attack occurs even when the lubricating oil composition leaks outside the torque limiter due to some cause or when it comes into contact with the synthetic resin molded product of the peripheral part.

As the emulsifier used in the present invention, any emulsifier can be used as long as it can emulsify minute water droplets mixed in a synthetic saturated hydrocarbon oil in a high-humidity environment in which condensation occurs. Suitable emulsifiers for the present invention include sulfonic acid metal salts represented by the following [Chemical Formula 3].
[Chemical formula 3]
(RSO ₃ ) nM
In [Chemical Formula 3], R is an alkyl group, an alkenyl group, or an alkylbenzene, M represents a metal, and an alkaline earth metal or alkali metal is preferable. Specifically, calcium, barium, magnesium, sodium and the like can be exemplified. n is 1 or 2. In the present invention, two or more of the above can be used in combination.

  As an effect | action of said emulsifier, the effect which prevents the oil film breakage is calculated | required by rapidly emulsifying the water which infiltrated into the lubricant. Therefore, the emulsifier needs to have a structure having both a hydrophobic group having an appropriate molecular weight and a highly polar hydrophilic group in the molecule. When water is present in a lubricant having a low viscosity, the oil film forming ability of the lubricant is low, so that the oil film is cut under the influence of emulsified water. However, when water is present in a lubricant having a high viscosity, the oil film forming ability of the lubricant is high, so that it is not easily affected by the emulsified water and the oil film is not easily cut.

  The compounding amount of the sulfonic acid metal salt as the emulsifier is 0.5 to 12% by weight based on the total amount of the base oil as the compounding amount of the sulfonic acid metal salt. If the blending amount is less than 0.5% by weight, the emulsifying properties are not effective, and if the blending amount exceeds 12% by weight, the solubility in the base oil, torque stability and chemical attack resistance are adversely affected. Considering the performance of the torque limiter in a high humidity environment and the chemical attack resistance, a more preferable blending amount is 1 to 8% by weight.

The emulsifier is preferably dissolved in a solvent excellent in chemical attack resistance, which will be described later, in order to improve compatibility with other oils and additives and promote emulsification. As the solvent excellent in chemical attack resistance, a nonpolar solvent is preferable, and examples thereof include mineral oil and synthetic saturated hydrocarbon oil.
The concentration of the sulfonic acid metal salt in the mineral oil or synthetic saturated hydrocarbon oil solution of the sulfonic acid metal salt is 20 to 80% by weight, preferably 30 to 70% by weight. For this reason, the compounding quantity of sulfonate metal salt mineral oil etc. becomes 2.5 to 15 weight% with respect to the base oil whole quantity.

Moreover, in this invention, it can be used as lubricating grease by mix | blending a thickener with the lubricating oil which contains the sulfonic acid metal salt as said base oil and an emulsifier as an essential component.
Thickeners used in lubricating greases are dispersed in base oil and take the role of forming a micelle structure and exhibiting a semi-solid state. Sodium soap, lithium soap, calcium soap, barium soap, calcium complex soap Metal soap such as aluminum complex soap, lithium complex soap, barium complex soap, etc. and benton, silica aerogel, sodium terephthalate, urea, polytetrafluoroethylene, hydroxyapatite, polyethylene powder and other inorganic substances, urea compounds, waxes, etc. Non-soap systems can be used. Preferably, a thickener such as a lithium-based soap or a urea compound having a balanced performance such as mechanical stability, heat resistance, and water resistance is suitable.

The lubricating oil or lubricating grease of the present invention can contain a phosphate ester as an antiwear agent.
As the phosphate ester, one represented by the following [Chemical Formula 4] is used.
[Chemical formula 4]
(RO) ₃ P = O
In the above [Chemical Formula 4], examples of R include an alkyl group, an alkenyl group, and an aryl group.

  As a compounding amount of the phosphoric acid ester as the antiwear agent, 1 to 8% by weight is blended with respect to the total amount of the lubricating oil. When the blending amount is less than 1% by weight, there is no effect in reducing wear and improving the torque stability, and when the blending amount exceeds 8% by weight, the chemical attack resistance is adversely affected. Considering the performance of the torque limiter and the chemical attack resistance, a more preferable blending amount is 3 to 5% by weight.

An example of a torque limiter using the lubricating oil or lubricating grease will be described. The above-described lubricating oil or lubricating grease is used to prevent the inner ring and spring or friction plate of the torque limiter, wear between the friction plate and the friction plate, abnormal heat generation, seizure noise, and the like.
The torque limiter shown in FIG. 1 is a friction type limiter that generates torque by the binding force of the coil spring 2 to the inner ring 1. The torque limiter is provided with a coil spring 2 having a large-diameter portion and a small-diameter portion on the outer side of the metal inner ring 1, and is locked to the lid 3 and the mantle 4 by spring hooks 2a and 2b. By rotating the lid 3 press-fitted into the outer cannula 4, the tightening force of the spring 2 against the inner ring is continuously changed, so that the torque can be freely adjusted. This is a one-way rotational torque limiter in which the rotation direction of the inner ring is limited by the winding direction of the spring.

  The torque limiter shown in FIG. 2 is provided with a cylindrical coil spring 2 on the outside of a metal inner ring 1 and is locked to the outer sleeve 4 by a hook 2b of the spring. In addition, since it is a cylindrical spring, torque adjustment cannot be performed, but by combining the ones with different tightening allowances for the inner ring, the spring tension changes, the torque value is determined, and torque adjustment is possible. This shape is also a one-way rotational torque limiter in which the rotation direction of the inner ring is limited by the winding direction of the spring.

  The torque limiter shown in FIG. 3 is provided with a cylindrical coil spring 2 on the outside of a separate metal inner ring 1 as in FIG. Further, since the spring is cylindrical, torque adjustment cannot be performed, but the torque value is determined by the tightening margin of the spring with respect to the inner ring. Also in this shape, the rotation direction of the inner ring is limited by the winding direction of the spring.

  The torque limiter shown in FIG. 4 has a friction plate 5 pressed against a metal inner ring 1 by a spring 2 and generates torque by a frictional force acting between the inner ring and the friction plate. Since the frictional force can be changed by the pressing force of the spring 2, torque adjustment is possible. In this shape, the rotation direction of the inner ring does not depend on the winding direction of the spring.

Examples 1 to 15 and Comparative Examples 1 to 23
Next, the torque limiter lubricating oil and the lubricating grease will be specifically described with reference to examples. Abbreviations for each component used in Examples and Comparative Examples are as follows. Further, the blending ratio is indicated by weight%. EM1-EM3 used the solution as it was.
PAO1: Poly-α-olefin oil (40 ° C. kinematic viscosity: 200 mm ² / S)
PAO2: Poly-α-olefin oil (kinematic viscosity at 40 ° C .: 900 mm ² / S)
TCP: tricresyl phosphate EM1: sulfonic acid metal salt-based emulsifier 1 (manufactured by Matsumura Oil Co., Ltd., Sulhol CA-45N, containing 45% by weight as sulfonic acid metal salt)
EM2: sulfonic acid metal salt emulsifier 2 (manufactured by Matsumura Oil Co., Ltd., Sulhol BA-30N, 31% by weight as sulfonic acid metal salt)
EM3: sulfonic acid metal salt-based emulsifier 2 (manufactured by Matsumura Oil Co., Ltd., Sulhol 400, 62% by weight as sulfonic acid metal salt)

Lubricating compositions in which the respective components were blended at the ratios shown in Table 1 and Table 2 were produced. Table 1 shows an example of an oily lubricating oil, and Table 2 shows an example of a lubricating grease using lithium soap (containing 20% by weight based on the whole grease) as a thickener. Note that “BaI” in Tables 1 and 2 represents the remaining amount other than the numerical value (% by weight) displayed with the whole as 100% by weight.

Lubricating oil and lubricating grease were evaluated by the following methods. The results are shown in Table 3 and Table 4.
<Torque stability test>
The test machine used was made in-house, and the torque limiter used for the evaluation was NTS18 made by our company. FIG. 5 is a diagram for explaining the structure of the torque stability tester, which is composed of a motor 6 for rotating the shaft, a load cell 7 for detecting torque, a coupling 8, a strain gauge 9, and a recorder 10. By setting the torque limiter 11 using a sintered inner ring impregnated with each sample oil on the rotating shaft and rotating it in the torque generating direction of the limiter, the generated torque is transmitted to the load cell and recorded by a recorder. The low-speed motor 12 is used by switching to the high-speed motor 6. Further, the left side of FIG. 5 is a view from above.
The test conditions were set torque 500 gf · cm, rotation speed 50 rpm, operation cycle 15 seconds of operation-1 second stop intermittent operation, ambient temperature: 40 ° C., humidity: 90%, test time 400 hours, and measurement items after test Changes in torque (time change, torque fluctuation for 1 minute) every hour, 200 hours, and 400 hours, and confirmation of chatter during operation were performed. Torque was measured every hour using a torque measurement tester shown in FIG. Test results ○ and X in Table 3 are symbols representing the results of the torque stability test. As a result of torque measurement for 1 minute, the torque drop is less than 30 gf · cm, “○”, and more than 30 gf · cm It was set as “x”. For items other than that, “○” was given to those that had a good hand feeling after the test, and “X” was given to those that were poor.

<Chemical attack resistance test>
Peripheral parts of the torque limiter are made of PC (polycarbonate) resin or ABS resin with good workability, and the resin material is cracked by contact with lubricating oil or lubricating grease due to leakage of the lubricant used in the torque limiter. And cracks may occur. Therefore, in order to confirm the chemical attack resistance of the lubricating oil of the present invention, a chemical attack resistance test was conducted using PC (polycarbonate) resin and ABS resin.
The chemical attack resistance can be evaluated by a bending test method in which the surface of the resin plate after applying mechanical stress to the polycarbonate resin plate and the ABS resin plate coated with lubricating grease or the like is observed.
The bending test method will be described.
(1) Test apparatus The schematic diagram of a bending test apparatus is shown in FIG.
The test apparatus 13 includes a test piece 14 that is supported so as to be movable at both ends at a predetermined test piece support point distance (L), a test table 15 on which the test piece 14 can be placed, and a deflection amount of the test piece 14. The probe 16 is provided with (B), and a deflection amount adjusting device 17 that supports the probe 16 and allows the probe 16 to move forward and backward.
(2) Test conditions Bending test piece: 127 mm (length) x 12.7 mm (width) x 6.5 mm (plate thickness)
Test piece support point distance: 100 mm
Specimen deflection amount (amount of deflection at the center of the distance between the support points): 3.5 mm
Test temperature: 70 ° C
Holding time: 3 hours Test piece material 1: Iupilon S2000R (PC resin; manufactured by Mitsubishi Engineering Plastics)
Specimen material 2: Stylac 321 (ABS resin; manufactured by Asahi Kasei Corporation)
(3) Test method Based on a three-point bending test. Lubricating oil or lubricating grease is applied to the surface of a bending test piece annealed at 120 ° C. for 2 hours, supported at the above-mentioned support point distance, and given a deflection amount from the back surface of the coated surface. Hold. The presence or absence of cracks after holding is visually confirmed. When the test piece was not cracked or cracked, “◯” was given, and when the test piece was cracked or cracked, “x” was given.

<Emulsification test>
An emulsification test was conducted according to JIS K 2520. The torque limiter lubricating oil and water were mixed and stirred at a weight ratio of 1: 1 to measure the degree of emulsification. For the lubricating grease for torque limiters, the degree of emulsification of the base oil with water was measured. As a result of the test, the emulsified product was designated as “◯”, and the product separated into water and lubricating oil was designated as “x”.

In order to satisfy the two requirements of maintaining good torque performance as a torque limiter in a high temperature and high humidity environment and excellent chemical attack resistance, as seen in each example shown in Table 3 and Table 4. It is necessary to use a predetermined amount of an emulsifier and a base oil (viscosity 900 mm ² / S) of a saturated synthetic hydrocarbon compound excellent in chemical attack resistance. Also preferred is the use of phosphate esters.
From the torque stability test of this test, it is necessary to emulsify water in the oil adhering to the bearing surface in order to achieve torque stability of the torque limiter particularly in a high humidity environment. It was suggested that the found emulsifiers are greatly related to their action. In Comparative Examples 5, 6, and 17 that do not contain an emulsifier, water that cannot be emulsified is mixed into the base oil, causing an oil film breakage, resulting in poor torque performance. As shown in each comparative example, even when the added amount of the emulsifier is 3 to 15% by weight as a solution, when the base oil viscosity is low, the oil film forming ability is low, so water enters the oil. Even if emulsified, chattering occurs. On the other hand, if the emulsifier exceeds 15% by weight as a solution, a problem of solubility in the base oil and a problem of long-term torque stability occur, and the chemical attack resistance is also adversely affected (Comparative Examples 12 and 22). Furthermore, there is an optimum amount of phosphate ester used as an anti-wear agent. If the amount used is less than 1% by weight, the torque stabilizing effect is poor, and if it exceeds 8% by weight, chemical attack resistance other than its performance is prevented. It adversely affects sex (Comparative Examples 13 and 23).
From the above results, the base oil is a synthetic hydrocarbon compound as a lubricating oil or lubricating grease for torque limiter that has excellent torque stability performance and excellent chemical attack resistance even in high temperature and high humidity environments. It is considered suitable that 1 to 8% by weight of the phosphate ester is blended with respect to the weight%, and 3 to 15% by weight of the sulfonate as a solution is blended with 100% by weight of the base oil as an emulsifier.

  The lubricating oil or lubricating grease for the torque limiter of the present invention has a low torque fluctuation and high torque stability even in a high temperature and high humidity environment, and is excellent in chemical attack resistance. It can be suitably used for a torque limiter used in a high humidity environment.

It is sectional drawing which shows an example of a torque limiter. It is sectional drawing which shows another example of a torque limiter. It is sectional drawing which shows another example of a torque limiter. It is sectional drawing which shows another example of a torque limiter. It is a schematic diagram of a torque stability test. It is a schematic diagram of a bending test apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inner ring 2 Coil spring 3 Cover 4 Mantle 5 Friction plate 6 High-speed motor 7 Load cell 8 Coupling 9 Strain meter 10 Recorder 11 Torque limiter 12 Low-speed motor 13 Bending test device 14 Test piece 15 Test stand 16 Probe 17 Deflection adjustment apparatus

Claims (6)

A lubricating oil for torque limiters, wherein an emulsifier is blended in a base oil composed of a synthetic saturated hydrocarbon oil having a kinematic viscosity at 40 ° C of 500 to 1200 mm ² / s.   The lubricating oil for torque limiter according to claim 1, wherein the emulsifier is a sulfonic acid metal salt.   The lubricating oil for torque limiter according to claim 1 or 2, wherein the emulsifier is a solution dissolved in a solvent that does not cause chemical attack. Lubricating grease for torque limiters, characterized in that an emulsifier and a thickener are blended in a base oil composed of a synthetic saturated hydrocarbon oil having a kinematic viscosity at 40 ° C. of 500 to 1200 mm ² / s.   5. The lubricating grease for torque limiter according to claim 4, wherein the emulsifier is a sulfonic acid metal salt.   6. The lubricating grease for torque limiter according to claim 4, wherein the emulsifier is a solution dissolved in a solvent that does not cause chemical attack.

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