JPH03217497A - Grease composition - Google Patents

Abstract

PURPOSE:To obtain a grease composition containing a specific base oil, Li salt, etc., of higher fatty acid and phosphonic acid based surfactant at a specific ratio, having excellent abrasion resistance and heat resistance and capable of providing high repeated durability to contact with copper. CONSTITUTION:The aimed composition containing (A) 100 pts.wt. base oil containing >=80wt.% polyoxypropyleneglycol monoalkylether expressed by the formula [R is 1-18C alkyl which may have branched chain; n is integer of 2-40 (preferably 8-30) and/or neopentylpolyol (ester), (B) 5-40 pts.wt. Li salt of higher fatty acid and/or nonpolar quaternary ammonium salt-treated clay mineral and (C) 0.05-3 pts.wt. phosphonic acid based surfactant.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a grease composition, particularly a wear-resistant grease composition suitable as a grease for copper-based sliding contacts of switches that are opened and closed under conditions of large currents.

BACKGROUND OF THE INVENTION Vehicles such as automobiles have come to be equipped with various devices and devices to ensure high safety, and as a result, there has been a demand for small switches with excellent durability. For this type of switch, it is desirable to use a direct load switching type copper contact from the viewpoint of multifunction and low cost.

However, this type of switch is exposed not only to arc heat and frictional heat during opening and closing, but also to corrosive environments and high contact pressure, which causes the copper contacts to easily oxidize and wear out. is requested.

The present applicant has previously provided a wear-resistant grease composition that can effectively prevent the progress of oxidation and wear of copper contacts (see Japanese Patent Laid-Open No. 1-182397).

Problems to be Solved by the Invention The present invention has been made in order to improve the grease composition and provide a grease that has excellent heat resistance and provides high repeated durability performance to copper contacts.

A means to solve the problem, that is, the present invention, is based on the general formula (I):
18 alkyl group, n is an integer from 2 to 40) A base oil containing 80% by weight or more of a polyoxypropylene glycol monoalkyl ether, an inopentyl polyol and/or an inactive pentyl polyol ester represented by 100 parts by weight, 5 to 40 parts by weight of a clay mineral treated with a lithium salt of a higher fatty acid and/or a quaternary ammonium salt having an affinity for organic matter, and 0.0 parts by weight of a phosphonic acid surfactant.
05 to 3 parts by weight of the grease composition.

The polyoxypropylene glycol monoalkyl ether represented by the general formula (1), which is a component of the base oil, can be obtained by adding a polyhydric alcohol, such as an alkylene glycol such as ethylene glycol, propylene glycol, or butylene glycol, to propylene oxide in a conventional manner. It is an oligomer prepared by addition polymerization.

In formula (I), R represents an alkyl group having 1 to 18 carbon atoms which may have a branched chain, and n represents an integer of 2 to 40, preferably 8 to 30.

The base oil used in the present invention contains the above-mentioned polyoxypropylene glycol monoalkyl ether, neobentyl polyol and/or neopentyl polyol ester.
Contains 0% by weight or more. This type of oil produces less soot during thermal decomposition, but when the content of these components is less than 80% by weight, this characteristic of producing less soot becomes weaker.

In addition to the above-mentioned components, the base oils used in the present invention include those commonly used in sliding culture greases from Yohei, such as hydrocarbon-based synthetic oils such as α-refined oil. Oil or the like may be appropriately blended within a range of 20% by weight or less.

The grease composition according to the present invention is produced by blending a predetermined amount of a lithium salt of a higher fatty acid and/or a quaternary ammonium salt-treated clay mineral having an affinity for organic matter, and a phosphonic acid surfactant as essential components into the base oil. prepared.

Examples of lithium salts of higher fatty acids include lithium stearate and/or lithium 12-hydroxystearate.

Examples of clay minerals treated with organic matter-compatible quaternary ammonium salts include dimethyldioctadecylammonium montmorillonite, dimethylbentyloctadecylammonium hectorite, montmorillonite containing aromatic ammonium compounds such as monoalkylbenzyltrialkylammonium compounds, and any of these. A mixture is exemplified.

The amount of lithium salts of these higher fatty acids and/or minerals added is 5 to 40 parts by weight per 100 parts by weight of the above base oil. parts, preferably 5 to 30 parts by weight, and if it is less than 5 parts by weight, the wear resistance will decrease when used in sliding contact grease, and the grease will become soft, resulting in poor shear stability and softening and leakage. It ends up.

Furthermore, if the amount is 40 parts by weight or more, the grease will be too hard and the applicability will be poor.

As a phosphonic acid surfactant, "Sepal 44110"
Examples include 0J and [Seval B566J (commercial product manufactured by Chukyo Yushi Co., Ltd.).

The blending amount of the phosphonic acid surfactant is 0.05 to 3 parts by weight, preferably 0.05 to 3 parts by weight, per 100 parts by weight of the above base oil.
If it is 1 part by weight or less, the effect will be small if it is less than 0.05 part by weight, and if it is more than 3 parts by weight, corrosion of the copper plate by phosphonic acid tends to progress in a high-temperature corrosive environment.

In addition to the above-mentioned components, the grease composition according to the present invention contains fine tin powder, if desired, to prevent wear due to lack of oil on the sliding surface, agglomeration of copper powder, and adhesion to the grease-applied surface of the insulator. This may further effectively prevent a decrease in insulation resistance when the durability cycles shown in FIGS. 4 to 14 are repeated.

The particle size of the fine tin powder is usually 5 to 10μ or less, and the blending amount is 2 to 15 parts by weight, preferably 2 to 10 parts by weight, and 2 parts by weight or less per 100 parts by weight of the above base oil. is not effective, and if the weight exceeds 15, it increases mechanical wear on the sliding surface, which is not preferable.

Furthermore, in place of or in addition to the above-mentioned components, the grease composition according to the present invention contains ultrafine tin dioxide powder of 1μ or less (approximately 0.02 to 0.2μ), or ultrafine tin dioxide powder heated in air at a high temperature of around 400°C. Base oil 100% of organic tin compound that produces tin dioxide
0.01-1 in terms of amount of Sn○2 produced per part by weight
It may be added in parts by weight.

In this case, since it is finer than the tin powder, the above effect can be achieved by adding a small amount. General formula (■) for organic tin compounds
: RnSnX*-n (II) [In the formula, R represents an alkyl group having 1 to 12 carbon atoms or a phenyl group, and X is S (CH 2)mCO○R'(
In the formula, R' represents an alkyl group or phenyl group having 1 to 22 carbon atoms, m represents a number of 1 to 8), and n represents a number of 1 or 2. be done.

This ultrafine powder or organic tin compound has no effect if it is less than 0.01 part by weight, and there is no need to use more than 1 part by weight.

Incidentally, aggregation of the copper powder and the fine tin powder is prevented by the action of the phosphonic acid surfactant.

The grease composition according to the invention may optionally further contain conventional additives, such as metal deactivators (penzotriazoles, thiadiazoles, N,N'' disalicylidene-1,
2-diaminopropane, etc.), secondary aromatic amine antioxidants (diphenylamine, 7-enylnaphthylamine,
phenolic antioxidants (2,6-butyl-n-methylphenol, etc.), and thickeners (liquid polybutadiene, olefin thickeners, etc.) etc. may be blended as appropriate.

Function When the grease composition according to the present invention is used as a grease for copper-based sliding contacts, the phosphonic acid-based surfactant adsorbs to copper powder generated by contact wear, reducing adhesive wear.
Coagulation and adhesion of copper powder to the greased surface of the insulator, which causes insulation deterioration, is effectively prevented.

Furthermore, by adding fine tin powder and fine tin dioxide powder to the grease composition which oxidize at high temperatures to form tin dioxide, a gap on the order of microns is formed between the contacts.
Since the oil component permeates into the gap by capillary action, it not only effectively prevents oil loss and wear at the contact points, but also
The fine powder is. It also acts as an oxidation catalyst for the hydrogen radicals and medium generated by thermal decomposition of base oil components by high-energy electric arc, so the medium (Co and C) is oxidized and CO2 is released.
As a result, the amount of grease carbide produced is reduced, hydrogen radicals are reduced, and copper contact wear powder is cleaned (
reduction) and the accompanying reduction in adhesive wear, the agglomeration and adhesion of copper powder to the greased surface is more effectively suppressed.

Hereinafter, the present invention will be explained by examples.

Example■. Preparation of Grease Composition Example 1 Grease composition 1 having the formulation shown in Table 1 was prepared as follows.

After sufficiently stirring and mixing the polyoxypropylene glycol monoether, α-olefin polymerized oil, and lithium stearate, stirring was continued under heating until the temperature of the mixture reached 185°C, then the heating was stopped and the mixture was left to cool. Stirring was continued, and when the temperature of the mixture reached 60°C, the quaternary ammonium salt-containing clay was added and thoroughly mixed. Next, methyl alcohol was added and mixed thoroughly, then heated again. When the temperature of the mixture reached 100°C, heating was stopped and penzotriazole and 2,6-ditertiary butyl 101 methylphenol were added. After the mixture was allowed to cool to room temperature, a phosphonic acid mold release agent and tin powder of micron order were added and mixed, and then subjected to finishing treatment using a three-stage roll.

Table 1 shows the properties of the obtained grease composition.

Example 2 Grease composition 2 having the formulation shown in Table 1 was prepared as follows.

After sufficiently stirring and mixing the holionole complex ester, polyoxypropylene glycol monoether, and lithium stearate, stirring was continued under heating until the temperature of the mixture reached 185°C, then the heating was stopped and the mixture was allowed to cool. When the temperature of the mixture reached 100°C, penzotriazole and 2,6-ditertiarybutyl=n-methylphenol were added, and after the mixture was allowed to cool to room temperature, a phosphonic acid release agent was added. After adding and mixing micron-order tin powder, the mixture was subjected to finishing treatment using a three-stage roll.

Table 1 shows the properties of the obtained grease composition.

Example 3 Grease composition 3 according to the formulation shown in Table 1 was prepared as follows.

After sufficiently stirring and mixing the polyol complex ester, polyoxypropylene glycol monoether, and quaternary ammonium salt-containing clay, methyl alcohol was added and thoroughly mixed, and the mixture was heated to a temperature of 100 ml.
When the temperature reached °C, heating was stopped, penzotriazole and 2,6-ditertiarybutyl-n-methylphenol were added, and the mixture was allowed to cool to room temperature, followed by a phosphonic acid mold release agent and a micron-order tin. After the powder was added and mixed, it was subjected to a three-roll finishing treatment.

Table 1 shows the properties of the obtained grease composition.

Example 4 Based on the procedure of Example 1, grease composition 4 was prepared according to the formulation shown in Table 1.

The properties of this composition are shown in Table-1.

Example 5 Based on the procedure of Example 3, grease composition 5 was prepared according to the formulation shown in Table 11.

The properties of this composition are shown in Table-1.

Comparative Examples 1 and 2 Based on the procedure of Example 1, grease compositions 1'' and 2' were prepared according to the formulations shown in Table 1.

The properties of these compositions are shown in Table-1.

Comparative Examples 3, 5 and 6 Grease compositions 3', 5' and 6' were prepared in accordance with the procedure of Example 2 and according to the formulations shown in Table 1.

The properties of these compositions are shown in Table-1.

Comparative Example 4 Grease composition 4' was prepared according to the procedure of Example 3 and the formulation shown in Table 1.

The properties of this composition are shown in Table-1.

■． Performance of grease compositions Grease compositions 1 to 5 and 1 prepared as above
The switch durability performance, low-temperature usability performance, and corrosion performance of the copper contacts of '~6' were measured as follows, and the results are shown in Table 2.

Test sample: A test sample shown in FIGS. 1 and 2 was prepared as a sliding switch similar to an actual sliding switch. Figure 1 is a plan view of the test sample;
FIG. 2 is a cross section taken along line AA' in FIG. 1. A fixed copper contact (2) was embedded in an insulator (1) made of nylon 66 containing an inorganic filler (silicate glass), and an air gap (3) was provided at the contact opening/closing portion to form a stator.

Apply sample grease (8) to the surface of the insulator (1).

In FIG. 1, (4) and (5) indicate a movable contact and a normally closed contact, respectively (see FIG. 3), and dotted lines indicate sliding trajectories of these contacts.

Test equipment 2 Test sample prepared as above (
6) is attached to the rotor fixed to the motor (7) shown in Figure 3, a load is applied as shown in the figure, and the motor is rotated to open and close the specified load (applied voltage:
DC14V, load: Rambl SOW, load switching speed: l
5 times/min). The opening/closing test is performed 50,000 times. In the area where the air gap (3) intervenes, the fixed contact (2)
Insulator at a position 3 mm away from the edge of (
1) Measure the insulation resistance.

(2) Low-temperature usability performance Evaluated by measuring starting torque and rotational torque at -30°C in accordance with JIS-K2205.

(3) Corrosion performance of copper contacts After puff finishing, a copper plate (0.7 cm x 7 cm x 3 mm) coated with sample grease at 10 mg/cm2 was left in a constant temperature bath at 60°C and 95% RH for 120 hours. Observe the discoloration of the surface and measure the contact resistance.

The contact resistance is measured using an electric contact simulator, and the conducting current lm
A. Measured under the condition of a contact pressure of 50 g.

(Hereinafter, blank spaces) Effects of the Invention The grease composition according to the present invention is a wear-resistant grease composition suitable as a grease for copper-based sliding contacts of switches that are opened and closed under conditions of large currents, and is heat-resistant. It has excellent durability and generates little abrasion powder at sliding contacts, giving copper contacts high repeated durability performance and making it possible to significantly downsize high-durability switches, especially automotive switches.

[Brief explanation of drawings]

FIG. 1 is a plan view of a test sample for a switch durability test. FIG. 2 is a sectional view taken along line AA' in FIG. 1. FIG. 3 is a sectional view of a switch durability test device. FIGS. 4 to 8 are graphs showing the relationship between the insulation resistance and the number of durability of insulators when Grease Compositions 1 to 5 are used for copper contacts, respectively. Figures 9 to 14 show grease compositions 1' to 6', respectively.
2 is a graph showing the relationship between insulation resistance and durability of an insulator when the insulator is used as a copper contact. (1) is an insulator, (2) is a copper fixed contact, (3 is
) is the air gap, (4) is the movable contact, (5) is the normally closed contact, (6) is the test sample, (7) is the motor, (8
) indicates sample grease.

Claims (1)

[Claims] 1. General formula (I): ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) (In the formula, R has 1 to 1 carbon atoms, which may have a branched chain.
18 alkyl group, n is an integer from 2 to 40) 100 parts by weight of a base oil containing 80% by weight or more of polyoxypropylene glycol monoalkyl ether, neopentyl polyol and/or neopentyl polyol ester , 5 to 40 parts by weight of a clay mineral treated with a lithium salt of a higher fatty acid and/or a quaternary ammonium salt having an affinity for organic matter, and 0.0 parts by weight of a phosphonic acid surfactant.
Grease composition containing 0.05 to 3 parts by weight. 2. The grease composition according to claim 1, containing 2 to 15 parts by weight of fine tin powder. 3. In addition to or in place of the micron-order fine tin powder according to claim 2, ultrafine tin oxide powder of 0.02 to 0.2 μm and/or tin oxide heated to 450° C. or higher in air is used. The grease composition according to claim 1, wherein the grease composition contains 0.01 to 2 parts by weight of the organic tin compound to be produced, in terms of SnO_2, based on 100 parts by weight of the base oil. 4. The organotin compound has the general formula (II): RnSnX_4-n(II) [wherein R represents an alkyl group or phenyl group having 1 to 12 carbon atoms, and X represents S(CH_2)_mCOOR'(
In the formula, R' represents an alkyl group or phenyl group having 1 to 22 carbon atoms, m represents a number from 1 to 8), and n represents a number from 1 to 2. The grease composition according to claim 3. 5. The grease composition according to claim 1 or 2, containing a metal deactivator and a secondary aromatic amine antioxidant.