JPS6031598A - Grease composition for ball joint - Google Patents

Abstract

PURPOSE:To provide the titled grease compsn. which shows a consistently appropriate and low operating torque both at high and low temps. and does not flow out even when joint shaft is turned downward or sideways, prepd. by adding a specified thickener and a wax to a high-viscosity poly-alpha-olefin-based synthetic oil. CONSTITUTION:The grease compsn. is prepd. by adding 6-30pts.wt. wax selected from among paraffin wax, polyethylene wax, microcrystalline wax and fatty acid amide wax and 1-50pts.wt. urea thickener (e.g. reaction product of diisocyanate and monoamine) to 100pts.wt. poly-alpha-olefin-based synthetic oil having a viscosity of 500-2,000cSt at 40 deg.C. The grease compsn. is esp. suitable for lubrication of a ball joint used in a steering link device and suspension of an automobile. It has advantages in that it is not affected by temp., shows a consistently appropriate value of operating torque, does not flow out even when the joint shaft is turned downward or sideways, contains no harmful substances and can be used safely.

Description

[Detailed description of the invention] The present invention relates to a grease composition for ball joints.

More specifically, it is a grease composition that is particularly suitable for use in lubricating ball joints made of metal ball studs and synthetic resin ball seats used in automobile directional steering link systems and wheel suspension systems. Regarding.

In the above-mentioned ball joint, in order to prevent so-called backlash, the clearance between the ball stud and ball seat is made as small as possible to minimize the displacement of the pole stud under load (hereinafter referred to as lift amount). On the other hand, from the viewpoint of improving steering stability, it is desirable that the operating torque of the pole stud be as low as possible and stable.

From this point of view, a lubricant is filled between the pole stud and the ball seat, but general lithium soap grease does not give good results. For example, when using general lithium soap grease, in the initial stage of use (new car e)
The torque is significantly large, and even after a certain amount of use, the torque is large and handling is not smooth. This is because the load applied to the pole stud pushes out the grease existing between the pole stud and the ball seat, causing a break in the grease film and causing contact between the metal ball part and the resin seat. . Furthermore, in the case of general lithium soap grease, the resin sheet wears out rapidly, shortening the life of the ball joint.

As a grease that can satisfy the above-mentioned requirements for ball joints, there is known a grease comprising an unsaturated aliphatic amide of a dibasic acid, an unsaturated aliphatic imide of a dibasic acid, and a low-temperature property improver. However, this grease has a large temperature dependence and tends to solidify particularly at low temperatures of about -60°C, so it appears that it does not have sufficient lubricity. In addition, since it solidifies at low temperatures, it has poor adhesion to metal balls, reducing workability. Furthermore, the dropping point is 62°C
Therefore, if the shaft of the joint is used downward or sideways, IL will flow out at high temperatures above the dropping point.
There is a mistake.

In view of the above-mentioned points, the present invention has been developed so that even if the clearance between the ball stand and the ball seat in the ball joint is reduced as much as possible, the operating torque is stable at an appropriate low value, and the operating torque is stable at a low temperature. There is little increase in torque and good adhesion, the dropping point is high at around 207°C or more, the operating torque N at high temperatures is small, and even when the shaft of the joint is used facing downward or sideways, there is little outflow and it can be used satisfactorily. To provide a grease composition that is free of harmful substances and can be used with peace of mind.

That is, in the present invention, (A) the viscosity is 4o0c and 500 to 2
000 cst poly-α-olefin synthetic oil 100 parts (parts by weight, the same applies hereinafter), (g)) Paraffin wax,
A ball joint comprising 6 to 60 parts of at least one wax selected from the group consisting of polyethylene wax, microcrystalline wax, and fatty acid amide wax, and (0) 1 to 50 parts of a urea-based thickener. The present invention relates to a grease composition for use in other applications.

The grease composition of the present invention uses the above-mentioned high viscosity poly-α-olefin synthetic oil as a base oil, thickens it with the above-mentioned specific thickener, and further contains waxes.

Therefore, the grease composition of the present invention having the above-mentioned composition is applied between the ball stud and the ball seat of the ball joint, which is composed of a ball stud made of a metal and a ball seat made of a coalesced resin. When filling, even if the clearance between the pole stud and the ball seat is made as small as possible, the rocking torque and rotational torque remain stable at appropriate low values. Furthermore, the grease composition of the present invention has low temperature dependence, for example -3
It exhibits the above-mentioned excellent characteristics in a wide temperature range of 0 to 90 degrees. Furthermore, the grease composition of the present invention has water resistance,
It has excellent rust prevention properties and does not adversely affect the synthetic resin ball seat of the ball joint or the rubber dust cover.

In the present invention, the poly-α-olefin synthetic oil used as the N component must have a viscosity of 500 to 2000 QEIt at 40'O (the same applies hereinafter). The lubricating oil film ruptures due to the load applied between the ball seat and the ball seat, and the torque increases.

When the viscosity is higher than 2000 cgt, the torque increases due to the viscous resistance.

As the poly-α-olefin synthetic oil, any oil used as a lubricating oil can be used as long as the viscosity is within the above range. For example, those having an average molecular weight of about 1000 to 2000 are used.

The waxes used as component ω) in the present invention are paraffin wax, polyethylene wax, microcrystalline wax, and fatty acid amide wax.

Paraffin wax has an average molecular weight of 300 to 5 and is mainly composed of linear hydrocarbons with an average carbon number of about 20 to 65.
A saturated hydrocarbon mixture with a melting point of 47-70'
A value of about 0 is used. Polyethylene wax has an average molecular weight of about 700 to 5000 and a melting point of 70.
~160°C is used. The microcrystalline wax is a saturated hydrocarbon mixture with an average molecular weight of about 400 to 1°C and a melting point of about 50 to 10°C, whose main component is a straight hydrocarbon with an average carbon number of about 65 to 50.
A material of about Oa is used. As the fatty acid amide wax, methylene bis (stearoamide), methylene bis (tetradecanamide), ethylene bis (sudet-a-tetraamide), ethylene bis (hexadecane amide), etc. are used.

The above-mentioned waxes may be used alone or as a mixture of two or more types, regardless of their type. In particular, a mixture of two to four types of waxes, paraffin wax, polyethylene wax, microcrystalline wax, and fatty acid amide wax, is preferably used. For example, in the case of a mixture of paraffin wax and polyethylene wax, the paraffin wax is 16 to 84% (weight%, the same applies hereinafter) based on the total amount of the wax mixture;
A proportion of polyethylene wax of 84 to 16% is preferred.

In the case of a mixture of paraffin wax, polyethylene wax, and fatty acid amide wax, paraffin wax 17-58% J-lyethylene wax 17-58%, fatty acid amide wax 50-1 based on the total amount of the wax mixture.
A 5% allowance is preferred. In addition, in the case of a mixture of the four types of waxes, paraffin wax is 17 to 47%, polyethylene wax is 17 to 4%, based on the total amount of the wax mixture.
Preferred proportions are 7%, microcrystalline wax 68-9%, fatty M/amide wax 68-9%.

The thickener used as component (0) in the present invention is a urea-based thickener. Conventional thickeners can be used without particular limitation, such as diurea compounds, polyurea compounds, and the like.

A diurea compound can be obtained, for example, by reacting a diisocyanate with a monoamine. Examples of diincyanates include phenylene diisocyanate, diphenyl diisocyanate, phenyl diisocyanate, diphenylmethane diisocyanate, octadecane diisocyanate, decane diisocyanate, hexane diisocyanate, etc., and examples of monoamines include octylamine, dodecylamine, hexadecylamine, octadecylamine, oleylamine, etc. .

Polyurea compounds are obtained, for example, by reaction of the corresponding diisocyanates with diamines. The diisocyanate used is the same as that used to produce the diurea compound, and the diamine includes ethylenediamine, butanediamine, butanediamine, hexanediamine, octanediamine, phenylenediamine, tolylenediamine, xylenediamine, etc. can be given.

The cyaurea compound and polyurea compound may be prepared in advance, or they may be formed on the spot by adding reactive components during the preparation of the grease composition.

The grease composition of the present invention has a ratio of (U to 100 parts of N component)
B) component from 6 to 60 parts, preferably from 14 to 22 parts, (0
) component in an amount of 1 to 50 parts, preferably 6 to 15 parts. If the ratio of component (B) is less than the above range, the initial operating torque will be large and the operation will be unstable when the ball joint is operated.If it is more than the above range, the grease composition will become hard and the operating torque will increase. Workability also deteriorates. If the proportion of component (0) is less than the above range, the composition will become fluid even at about 70°C, and component (A) will easily flow out, while if it is greater than the above range, the composition will become too hard.

The composition of the present invention may further contain commonly used additives such as rust preventives and antioxidants, as appropriate, within a range that does not impair the above-mentioned properties.

The composition of the present invention may be prepared according to conventional methods.

Next, the grease composition of the present invention will be explained with reference to Examples and Comparative Examples.

Example 1 4.4I-diphenylmethane diisocyanate 20.6
9 is poly-α-olefin synthetic oil (viscosity 1200cII
t, hereinafter referred to as synthetic oil A) 500g plus 100°Q
It was heated to dissolve uniformly. To this solution was added a solution in which stearylamine 44.49 was added to synthetic oil A3009 and heated to 90°0 to uniformly dissolve it, and while stirring,
After heating to OA and cooling to 150°O, polyethylene wax (average molecular ffi 1500.8 points 10
5'0) 65g, Mike Four Crystalline Wax (
46 g (melting point 80'O), paraffin wax (melting point 56
°'0) 659 and ethylene bis(steartetraamide)
469 was added, stirred and dissolved, the mixture was cooled to room temperature and treated with a 'Nilreid mill to obtain a grease composition. This grease composition had a consistency of 264 and a dropping point of 207°0.

Example 2 4.4/-diphenylmethanediyne silicone) 25.0
gwo was added to 500 g of synthetic oil A and heated to 50°0 to uniformly dissolve it. To this solution, add a solution in which octylamine 1S, 2P was added to synthetic oil A 2009 and dissolved uniformly,
Heat to 100°0 while stirring, then add 26.89 g of stearylamine to 270 g of synthetic oil A at 90oO
Add the uniformly dissolved solution and heat to 180°0 while stirring, cool to 150°0,
To this were added 65 g of the same polyethylene wax as in Example 1, 46 microcrystalline waxes, 65 g of Habara Fine Wax, and 469 ethylene bis(stearamide), stirred, cooled to room temperature, and treated with a colloid mill to obtain a grease composition. This grease composition had a consistency of 248 and a dropping point of 256°0.

Example 3 4.4ζ diphenylmethane diisocyanate 25+89
was added to Synthetic Sennin 5009 and heated to 50°C to uniformly dissolve. A solution in which 58.29 dodecylamine was added to 4609 of synthetic oil A and uniformly dissolved was added to this solution and stirred. Heat to 180°C while stirring to 150°
128 g of the polyethylene wax used in Example 1, 102 g of bar IF fin wax, and ethylene bis(stearamide) 1029 were added thereto and dissolved with 1 stirring, then cooled to room temperature and processed with a colloid mill to obtain a grease composition. I got it. This grease composition had a consistency of 257 and a dropping point of 246°0.

Example 4 4.41-diphenylmethane diisocyanate 20.6
g was added to 500 g of Synthetic Sennin and heated to 5,000 ℃ to uniformly dissolve. To this solution, a solution of stearylamine 44.49 added to 500 g of synthetic oil A and heated to 100°0 was added and heated to 180°0 with stirring, and then heated to 160°
Then, 120p of polyethylene wax (average molecular weight 1500, melting point 118°0) and 120g of paraffin wax (melting point 65°0) were added and dissolved with stirring, cooled to normal humidity, and then treated with a colloid mill to obtain a grease composition. I got it. The consistency of this grease composition is 216
, the dropping point was 216°a.

Example 5 4.4'-diphenylmethane diisocyanate 25. O
P was added to 500 g of synthetic oil A and heated to 50°0 to uniformly dissolve. To this solution, add 15.2p of octylamine to 200g of synthetic oil A and add a uniformly dissolved solution, heat to 100°C while continuing to stir, add 26.69p of oleylamine to 270g of synthetic oil A and add 9000g of octylamine to 270g of synthetic oil A. Add the uniformly dissolved solution by heating to
After heating to 80°0, it was cooled to 16,000°C, then 120p of polyethylene wax (melting point 79°0) and 100g of ethylene bis(steartetraamide) were added and dissolved with stirring, cooled to room temperature, and processed with a colloid mill to form a grease composition. I got it. This grease composition had a consistency of 240 and a dropping point of 268°O.

A grease consisting of the grease compositions obtained in Examples 1 to 5, a commercially available unsaturated aliphatic amide of a dibasic acid, an unsaturated aliphatic imide of a dibasic acid, and a low temperature property improver (Comparative Example 1) ), commercially available lithium soap grease (grave viscosity:
154.1 cst) (Comparative Example 2), Example 1 (
4) component poly-α-olefin synthetic oil of 552aa
Test properties, operating torque and fire resistance when used in ball joints for a grease composition changed to that of T (Comparative Example 3) and a grease composition excluding component (B) of Example 1 (Comparative Example 4) Table 1 shows the results of the measurements.

(Torque measurement method) The following ball joint was used.

Ball stud material: 80r4q Ball diameter: 22±0.04m+n Ball seat material: Boria heptatar and polyester elastomer GM length in the longitudinal direction of the ball joint: o, 5
After applying each grease uniformly to the ball portion of the pole stud and the surface of the ball seat, assembly was carried out. To measure torque, fix the ball joint socket, attach a 70mm long shaft from the center of the pole stud ball, attach a torque wrench to this shaft, rotate the shaft, and measure the torque at that time. Ta. Further, the torque when the device is rotated for the first time after being left alone was defined as static torque, and the torque after twisting the pole stud 20 times was defined as dynamic torque.

[Fire resistance measurement method]

A durability test was conducted on the assembled ball joints coated with each grease as described above under the following conditions, and the durability was expressed as the increase in lift of the pole stud.

Test conditions 1) Temperature 25'O V load Axial direction of melon pole stud ±450 kg, 40 cpm Radial direction of pole stud ±200 kg, 60 cpm 6) Motion swing of pole stud ±600.70 cpm Rotation ±60°, 55 cpm In the above The amount of lift refers to the amount of movement of the pole stud relative to the socket when the socket of the ball joint is fixed and a predetermined load in a predetermined direction is statically applied to the pole stud.

In this test, the amount of lift is measured by adding 9 to the pullout load 900 in the axial direction of the socket to the pole stud, and the increased amount of lift refers to the amount of increase of 7 tons.

From Table 1, compared to Examples 1 to 5, (A) of Comparative Example 3
It can be seen that the operating torque increases when the viscosity of the components is lowered. It can also be seen that when the wax component (B) of Comparative Example 4 is removed, the operating torque increases. Commercially available lithium grease (Comparative Example 2) has a very large operating torque.

Continuation of page 1 [Phase] Int, CI,' Identification symbol Internal office reference number 50
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Claims (1)

[Claims] 1 (A) 100 parts by weight of poly-α-olefin synthetic oil having a viscosity of 4,000 and 500 to 2,000 cst; (B) at least one member selected from the group consisting of paraffin wax, polyethylene wax, microcrystalline wax, and fatty acid amide wax. 1. A grease composition for a ball joint, comprising 6 to 60 parts by weight of wax, and (0) 1 to 5 parts by weight of a urea thickening agent.