JPH07197070A - Composition for working, lubrication and fluid coupling - Google Patents

Abstract

PURPOSE:To obtain the subject composition which change little in its viscosity with changing shearing force and gives suitable torque transmissibility by adding suitably controlled amount of a silicon oxide powder to a base oil such as polyorganosiloxane. CONSTITUTION:Silicon oxide powder in an amount of 20 pts.wt. or below is added to 100 pts.wt. base oil. A representative example of the base oil is a polyorganosiloxane having a viscosity of 50-500000mm<2>/s at 25 deg.C, and another example is a mineral oil. Because of their good dispersion stability, amorphous silicon oxide powders such as white carbon and Aerosil are desirable as the silicon oxide powders used. These powders have a mean particle diameter of 50mum or below. The shear-viscosity characteristics can be changed by changing the amount of the silicon oxide added, and especially when this amount is 5 pts.wt. or below, the rate of change in viscosity in a high-shear region and a low-shear region can be decreased. Therefore, a fluid composition which is the most suitable for a fluid coupling which must develop low torque transmissibility in a low-shear region (in a region of a low differential rotation speed) can be given.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a working / lubrication / fluid coupling composition having excellent shear-viscosity characteristics.

[0002]

2. Description of the Related Art For example, a differential mechanism for the purpose of driving stability of a vehicle and escape from a bad road, a viscous coupling mounted on a four-wheel drive propeller shaft mechanism,
As a fluid composition used for other fluid couplings, a viscous liquid containing, for example, silicone oil as a base oil has been conventionally used. In addition, an inorganic filler, specifically calcium carbonate, is added as an additive, and a viscous fluid having a small decrease in viscosity even when subjected to high shearing force is disclosed in JP-A-4-36339.
No. 2 is disclosed.

[0003]

Generally, the fluid composition as described above has a characteristic that its viscosity decreases when a high shearing force is applied. Therefore, when the rotational speed difference between the input side and the output side of the fluid coupling is large and the fluid is in a high shear state, the viscosity of the fluid composition is reduced and the torque transmission rate is reduced. In order to prevent this, when a fluid composition having a high viscosity is used, the torque transmissibility becomes large when the rotational speed difference is small.
Therefore, the torque transmissibility may become too large and the characteristics of the fluid coupling may be impaired. In this way, for certain applications (that is, increasing the torque transmission rate in the region where the rotational speed difference is high,
In addition, it is not suitable for applications where it is expected that the torque transmissibility will be kept low in a low region).

Therefore, there is a demand for a fluid composition whose viscosity is less likely to be affected by the magnitude of shearing force (or the difference in the number of rotations) and whose viscosity changes little.

More generally, a fluid which can appropriately control the viscous characteristic or the torque transmissibility even in a high shearing force region and a low shearing force region, and can appropriately adjust the shearing-viscosity characteristic based on the above-mentioned specific requirements. A composition is sought.

[0006] It is an object of the present invention to provide a fluid for lubrication / actuation / fluid coupling which can more appropriately deal with such a demand than the conventional one.

[0007]

The present invention relates to a composition for working / lubrication / fluid coupling, which is obtained by adding 20 parts by weight or less of silicon oxide powder to 100 parts by weight of a base oil, and a base oil 10.
A working / lubrication / fluid coupling composition comprising 5 parts by weight or less of silicon oxide powder with respect to 0 parts by weight.

[0008]

In the present invention, the shear-viscosity characteristics can be adjusted without depending only on the base oil by using silicon oxide powder as an additive and adjusting the content thereof appropriately.

In particular, by setting the content to be 5 parts by weight or less, it is possible to reduce the change in viscosity between a state where the shearing force (or a rotational speed difference) is high and a state where the shearing force is low. That is, even when the difference in the number of revolutions is small, the viscosity is not too high and the transmission torque can be kept low.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION A base oil usable in the present invention is 25 ° C.
A polyorganosiloxane having a viscosity of 50 to 500,000 mm ² / s in is typical. Preferably, 500 to 5
It is the one of 0,000 mm ² / s. Typically,

[0011]

[Chemical 1]

[Wherein each R may be the same as or different from each other and represents an optionally halogenated hydrocarbon group having 1 to 18 carbon atoms, and n is 1 to 3000 (particularly preferably 40 to 40). It is an integer of 1500)].

R is a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, a t-butyl group, an n-pentyl group, a neopentyl group,
Alkyl group such as hexyl group, heptyl group, octyl group, decyl group and octadecyl group; aryl group such as phenyl group and naphthyl group; aralkyl such as benzyl group, 1-phenylethyl group and 2-phenylethyl group Group; araryl group such as o-, m-, p-diphenyl group; o-, m-, p-chlorophenyl group, o-, m
-, P-bromophenyl group, 3,3,3-trifluoropropyl group, 1,1,1,3,3,3-hexafluoro-2-propyl group, heptafluoroisopropyl group and heptafluoro-n-propyl group A halogenated hydrocarbon group such as a group. Particularly preferred as the group R are fluorinated hydrocarbon groups having 1 to 8 carbon atoms excluding aliphatic unsaturated groups, methyl group and phenyl group, and a mixture of dimethylpolysiloxane and phenylmethylpolysiloxane is used. May be. Alternatively, an alkyl-modified polysiloxane may be used.

As the other base oil, mineral oil, alkylbenzene, poly-α-olefin, polyalkylene glycol, ester, alkyldiphenyl, alkyldiphenyl ether and the like may be used. These can also be mixed and used.

The silicon oxide powder used in the present invention may be crystalline, but amorphous ones such as white carbon and aerosil are preferable from the viewpoint of dispersion stability.

The average particle size of the powder is preferably 50 microns or less. Anything more than that is not practical because the dispersion stability is poor.

The "silicon oxide powder" referred to in the present invention also includes powders other than silicon oxide coated with a silicon oxide compound. It can be prepared, for example, by binding a silicon compound to the surface of powder other than silicon oxide and oxidizing it.

In the present invention, the shear-viscosity characteristics can be adjusted by selecting the addition amount of silicon oxide within a specific range (20 parts by weight or less).

In particular, silicon oxide powder is added to the base oil in an amount of 5
By adjusting the amount to be less than or equal to the weight part, the change rate of viscosity in the high shear region and the low shear region can be reduced. Therefore, it is optimal as a fluid coupling that requires a low torque transmission rate in a low shear region.

In the present invention, any additive can be added to the base oil in order to enhance the performance of the composition for actuation / lubrication / fluid coupling. Examples thereof include antioxidants, corrosion inhibitors, antiwear agents, metal deactivators, rust inhibitors, antifoam agents, viscosity index improvers, pour point depressants, and the like.

The present invention can be used for various purposes, but is particularly effective for viscous couplings and fan couplings for fluid couplings.

[0022]

EXAMPLES Example 1, Comparative Examples 1-3 Polydimethylsiloxane (100,000 mm at 25 ° C.
² / s) 100 parts by weight of silicon oxide (trade name: Syloid (particle size: 1.4 μm), manufactured by Fuji Devison Chemical Co., Ltd.) was added to 2 parts by weight to prepare a viscous fluid according to the present invention. The change in shear viscosity was examined. The results are shown in Table 1.

As a comparative example, polydimethylsiloxane 10
Shear viscosity change for a composition obtained by adding 30 parts by weight of calcium carbonate powder to 0 parts by weight, a composition obtained by adding 30 parts by weight of the silicon oxide used in Example 1 to polydimethylsiloxane alone and 100 parts by weight of polydimethylsiloxane. I also checked. The results are also shown in Table 1.

[0024]

[Table 1]

As is apparent from this table, the shear-viscosity properties are greatly improved by adding silicon oxide powder. That is, the change in viscosity is small when the shearing force is low and when the shearing force is high. Further, it can be seen that even when a larger amount of calcium carbonate is added, the change in viscosity due to the change in shearing force is small.

That is, the addition of silicon oxide suppresses the change in viscosity due to shearing. Therefore, the transmission torque in the low shear region can be controlled to be lower than that in the case of adding polydimethylsiloxane alone (Comparative Example 1) and 30 parts by weight of calcium carbonate (Comparative Example 2). Furthermore, when the addition amount of the silicon oxide powder exceeds 20 parts by weight, the composition loses fluidity and cannot be used as a fluid composition (Comparative Example 3).

Examples 2 to 4, Comparative Examples 4 and 5 Obtained by adding 1.0% by weight of diphenylamine as an antioxidant and 0.1% by weight of dithiocarbamate as an antiwear agent to polydimethylsiloxane. Base oil 100
Silicon oxide powder (trade name Aerosil, manufactured by Nippon Aerosil Co., Ltd.) and silicon oxide used in Example 1 (trade name: Cyloid, manufactured by Fuji Davisson Chemical Co., Ltd.) were added to parts by weight, A fluid composition was prepared. Polydimethylsiloxanes, 100,000 mm at 25 ° C. ² /
mixed and used as the s and 300,000mm ² / s, when the composition is a shear rate 3000 s ^-1, the viscosity of the product is identical to the shear viscosity of the polydimethylsiloxane 300,0000mm ² / s Was adjusted.

The fluid composition prepared was filled into a viscous coupling having 111 discs at 25 ° C. and a filling rate of 85% by weight.

The filled unit was heated to 100 ° C., and a rotation speed difference was given at a speed of 20 rpm / s up to a maximum of 100 rpm. With respect to the input torque at 25, 50 and 100 rpm, Table 2 shows the change when the torque at 100 rpm is 1. 300,000m for comparison
A fluid composition obtained by adding 1.0% by weight of diphenylamine and 0.1% by weight of dithiocarbamate to polydimethylsiloxane of m ² / s (Comparative Example 4), and 30 parts by weight of calcium carbonate was added to the fluid composition of Example 3. The same evaluation was performed on the fluid composition (Comparative Example 5).

[0030]

[Table 2]

As is clear from the above results, by adding the silicon oxide powder, the input torque can be kept low even in the region where the difference in rotational speed is low.

[0032]

As described above in detail, according to the present invention, the viscous characteristics or the torque transmission rate can be appropriately controlled in both the high shearing force region and the low shearing force region. In particular, it is possible to provide a fluid composition having a small change in viscosity regardless of whether the shearing force (rotational speed difference) is large or small.

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication location C10N 30:02 40:04 40:08 (72) Inventor Toshiaki Kuribayashi Nishitsurugaoka, Oi-cho, Iruma-gun, Saitama Prefecture 1-3-1 Tonen Co., Ltd. Research Institute

Claims (1)

[Claims] 1. A composition for working / lubrication / fluid coupling, comprising 20 parts by weight or less of silicon oxide powder added to 100 parts by weight of base oil.