JPH0631386B2 - Sliding contact grease composition with improved syneresis - Google Patents

Description

TECHNICAL FIELD The present invention relates to a grease composition used for a contact sliding portion of an electric switch, and more particularly to a grease composition with a particularly small amount of syneresis.

[Conventional technology and its problems] Conventionally, grease has been used for sliding contact parts of electric switches, and it is inevitable to keep smooth operation and durability of switches. Many problems have been raised.

That is, 1) The amount of grease adhered to the contact surface is small or the grease disappears to form an oxide film on the contact surface, which increases the voltage drop.

2) Insulation deterioration occurs due to evaporation and scattering of contact metal due to arc and adhesion of grease carbide to the insulator.

3) Chattering of the contact causes an induced voltage.

4) The plastic insulator swells depending on the type of base oil.

The above problems are raised, and as a means for solving these problems, development of grease having the following characteristics is desired.

1) When an electric arc is generated, no foreign matter that causes a high voltage drop on the contact surface is generated.

2) Little contact wear and wear even at high temperatures such as electric arcs.

3) Carbide residue is small even when heated at high temperature such as electric arc.

4) It is a resistor showing negative characteristics showing low resistance at high temperature,
No induced voltage is generated by contact chattering.

5) It can be used in a wide temperature range from low temperature to high temperature (-30 ° C to 150 ° C).

6) Do not put plastic such as polycarbonate or ABS.

7) The degree of oil separation is small and the grease does not change over time.

As a grease composition satisfying such characteristics, a mixed oil of an alkylene oxide-polyhydric alcohol addition polymerization oligomer and a chain hydrocarbon oligomer is used as a base oil, and an organic lipophilic quaternary ammonium salt-containing clay product and a higher grade The applicants have proposed a grease for sliding contacts containing a lithium salt of a fatty acid (JP-A-1-152197).

In recent years, as the mechanism and structure of the contact portion have become more precise and higher performance has been required, the grease used in this portion is also required to have more severe properties that match the performance.

Among them, the property that needs to be improved year by year is syneresis prevention of grease. There is a risk that the oil will be bleeding out of the grease applied to the sliding contact part, and that it will be extracted to parts other than the contact and contaminate it, as well as cause troubles that reduce performance. There is a strong demand for low-grease grease compositions.

The present invention provides a grease composition having less syneresis while maintaining more effective performance for lubrication of sliding contacts for the purpose of satisfying such demands.

[Means for Solving Problems] The grease composition for sliding contacts according to the present invention is characterized by being configured as follows.

That is, 80 to 95 parts by weight of the alkylene oxide-alcohol addition polymerization oligomer and the chain hydrocarbon oligomer 5
~ 20 parts by weight of base oil 100 parts by weight, organic lipophilic No. 4
It is characterized by containing 5 to 20 parts by weight of a primary ammonium salt-containing clay mineral, 5 to 30 parts by weight of a lithium salt of a higher fatty acid, and 0.2 to 20 parts by weight of an alkylenebisaliphatic monocarboxylic acid amide.

The alkylene oxide-alcohol addition polymerization oligomer used in the present invention is produced by ring-opening polymerization of one or more compounds selected from alkylene oxides such as ethylene oxide, propylene oxide and butylene oxide with alcohol as an initiator. To be
The molecular weight is usually 300 to 4000, preferably 1000 to 2000.
A particularly suitable addition-polymerization oligomer of this type is exemplified by polyoxypropylene glycol monoether. As the polyoxypropylene glycol monoether, commercially available products can be used, and examples thereof include Newpol (trademark) LB series manufactured by Sanyo Kasei Co., Ltd.

Examples of the chain hydrocarbon oligomer used in the present invention include refined paraffinic mineral oil, α-olefin polymerized oil, ethylene / α-olefin polymerized oil and the like, but the molecular weight of these oligomers is usually 400 to 3000, preferably 500. ~ 1500
Is. Particularly suitable oligomers of this type are hydrogenated α-olefin oligomers having 6 to 12 carbon atoms.

As the α-olefin polymerized oil, those commonly used can be used, and examples thereof include Paol (trademark) manufactured by Bray Oil Company, Inc. and Lipolvo (trademark) manufactured by Lion Oil & Fat Co., Ltd.

The base oil according to the present invention comprises 80 to 95 parts by weight of the above alkylene oxide-alcohol addition polymerization oligomer and 5 to 20 parts by weight of a chain hydrocarbon oligomer.

Of the base oils used in the grease composition, the α-olefin oligomer is necessary to maintain the low temperature characteristics, but if the blending ratio of this is too much, the amount of wear of the contacts increases and the Adhesion of abrasion powder is seen. On the other hand, if the amount is too small, the switching power is large, and when an arc is generated during switching, the carbide residue of the base oil increases due to arc heat and adheres to the insulator, causing insulation deterioration. Thus, the base oil of two kinds of the components constituting the present invention and the mixing ratio thereof play an important role in exerting the characteristics of the contact grease.

The grease according to the present invention is an organic lipophilic quaternary ammonium salt per 100 parts by weight of a base oil consisting of 80 to 95 parts by weight of the above alkylene oxide-alcohol addition polymerization oligomer and 5 to 20 parts by weight of a chain hydrocarbon oligomer. 5 to 20 parts by weight of contained clay mineral and lithium salt of higher fatty acid 5 to 30
Parts by weight, alkylene bis aliphatic monocarboxylic acid amide
It is adjusted by compounding 0.2 to 20 parts by weight.

Various types of thickeners such as metallic soaps, inorganic type and organic type thickeners have been conventionally known.

Metallic parts of metallic soap include sodium, potassium, calcium, barium, strontium, aluminum,
Examples of the fatty acid portion of the metal soap include various fatty acids, or a mixture of fatty acids, and a so-called complex soap in which a fatty acid and another acid such as acetic acid, benzoic acid, boric acid, dicarboxylic acid, and salicylic acid are combined. I can mention the type. These fatty acids are generally fatty acids obtained by decomposing glycerin ester contained in animal fats, vegetable oils, waxes or the like, or artificially generated chain fatty acids. Typical examples of such fatty acids include myristic acid, palmitic acid,
Examples thereof include saturated fatty acids such as stearic acid, unsaturated fatty acids such as oleic acid, and fatty acids such as 12-hydroxystearic acid.

The present invention comprises a lithium salt of a higher fatty acid as a constituent feature. Lithium salts of higher fatty acids, in addition to their effect as thickeners,
It is blended in order to enhance the boundary lubricity, because a resin blended with an inorganic additive such as general or glass fiber may be used as the insulating resin.

As such a thylium salt, lithium stearate,
Lithium 12-hydroxystearate and a mixed soap of lithium stearate and lithium 12-hydroxystearate are particularly suitable, and the amount thereof is 100% of the above base oil.
If the amount is 5 to 30 parts by weight with respect to 5 parts by weight and the amount is 5 parts by weight or less, wear of the contacts and the insulator is inferior, and if 30 parts by weight or more, the applicability of grease is deteriorated.

Examples of the inorganic thickeners include bentonite, colloidal silica, silica airgel, alumina, graphite, mica, talc, clay, diatomaceous earth, and quaternary ammonium salt-containing clay minerals.

Examples of the organic thickeners include urea thickeners and the like. Typical examples thereof include diurea type and tetraurea type. Other organic thickeners include urea-based, indanthrene-based, phthalocyanine-based, amelin-based and the like.

The present invention comprises an organic lipophilic quaternary ammonium salt-containing clay mineral as a constituent element. Examples of the quaternary ammonium salt-containing clay mineral include dimethyl octadecyl ammonium montmorillonite and dimethyl pentyl octadecyl ammonium hectorite manufactured by Kunimine Industry Co., Ltd., and organic compounds obtained by adsorbing Barragel (trademark) manufactured by National Red Corporation, that is, monoalkylbenzyl trialkyl ammonium. Examples thereof include bentonite and Organite (trademark) manufactured by Japan Organoclay Co., Ltd., that is, organic bentonite having dimethylalkylbenzylammonium adsorbed thereon.
You may merge more than one kind.

To use the quaternary ammonium salt-containing clay mineral, add it to the base oil and mix it well, then add methyl alcohol and mix it well, and heat it again to bring the temperature of the mixture to 180 ° C.
Up to. As a result, the quaternary ammonium salt-containing clay mineral swells well in the base oil. In addition to methyl alcohol, acetone, ethyl alcohol, etc. may also be used.

When the compounding amount of the quaternary ammonium salt-containing clay mineral is 5 parts by weight or less, it is not possible to impart a sufficient consistency to the grease, and when it is 20 parts by weight or more, the consistency of the grease is increased and the applicability of the grease is increased. In addition to this, this component remains as ash when exposed to high temperature of arc heat and may remain between the electrical contacts, which is not preferable.

Further characterizing the present invention is alkylenebisaliphatic monocarboxylic acid amide. Here, the alkylene group is a divalent hydrocarbon group having 1 to 6 carbon atoms, and the aliphatic monocarboxylic acid is an aliphatic monocarboxylic acid having 6 to 24 carbon atoms. There are two aliphatic monocarboxylic acids in one molecule, but they may be the same as or different from each other. An example of this is an organic amide wax manufactured by Ito Oil Co., Ltd. The said organic amide wax uses hardened castor oil fatty acid etc. as a raw material.
The main component of hydrogenated castor oil fatty acid is 12-hydroxystearic acid. The organic amide wax manufactured by Ito Oil Co., Ltd. is ASA T-300-20AK, ASA D-10A, ASA T-75F.
Are added to paints, they form a stitch structure and exert strong thixotropy, and are said to impart excellent sag prevention performance and pigment settling prevention performance to paints. ASA T-300-20AK is a paste of 20% active ingredient, solvent xylene-alcohol, ASA D-10
A is a paste of 20% active ingredient, solvent xylene, AS
-A T-75F is a white fine powder.

As described above, the α-olefin oligomer in the base oil used in the grease composition is necessary to maintain the low temperature characteristics, but if the blending ratio of this is increased, the wear amount of the contact increases and the wear to the insulator. Adhesion of powder is seen. On the other hand, if the amount is too small, the switching power is large, and when an arc is generated during switching, the carbide residue of the base oil increases due to arc heat and adheres to the insulator, causing insulation deterioration. Thus, the base oil of two kinds of the components constituting the present invention and the mixing ratio thereof play an important role in exerting the characteristics of the contact grease.

However, since the alkylene glycol-based synthetic oil and the α-olefin oligomer are not compatible with each other, if they are made into a grease with a thickener in this state, a large amount of syneresis occurs, resulting in a poorly adherent grease.

Further, if a large amount of oil separation causes a large amount of one of the oils to flow out, a phenomenon occurs, which causes a problem in that the balance of the compounding is lost and the contact failure occurs due to the change with time of the grease.

What was added for the purpose of preventing this is a quaternary ammonium salt-containing clay mineral, a so-called bentonite-based thickener. By adding this, two or more incompatible base oils are used as base oils. Can produce a good grease composition. However, in order to have this characteristic, it is necessary to swell the bentonite type thickener in the base oil, and the desired characteristics cannot be obtained unless so-called Benton grease is produced.

In such a method, a good grease composition is prepared by using two or more types of insoluble oils as a base oil, but when a grease composition with less syneresis is required, this is not enough. I can't get it.

Therefore, alkylenebisaliphatic monocarboxylic acid amide is added for the purpose of further reducing syneresis of the grease composition.

Addition of the alkylenebis-aliphatic monocarboxylic acid amide to the grease composition improves the dispersion of the bentonite-based thickener, and forms a network structure in the base oil to hold the base oil firmly. For this reason, the oil that is released from the grease is retained by the network structure formed by the alkylenebisaliphatic monocarboxylic acid amide, and the separation is prevented.

Thus, the alkylenebis-aliphatic monocarboxylic acid amide firstly disperses the bentonite-based thickener to form a better grease structure, and then the alkylenebis-aliphatic monocarboxylic acid amide itself has a solid network structure. Forming a structure exerts the effect of reducing oil separation and syneresis.

In the present invention, various additives such as antioxidants can be used.

As antioxidants, various antioxidants such as phenol-based, amine-based, organic acid-based and sulfur compound-based antioxidants are known,
Both can be used, but among them, phenol-based 2,6
-Ditertiary butyl-4-methylphenol is most suitable.

In order to further improve the lubricity, an organic molybdenum compound, for example, molybdenum dithiocarbonate may be added in an amount of 0.1 to 5 parts by weight.

If desired, various conventional additives and polymer thickeners may be appropriately added to the grease of the present invention to adjust the clay index and oil separation degree of the grease.

The grease composition of the present invention is prepared by the following method. Polyoxypropylene glycol monoether, α
After thoroughly stirring and mixing the olefin polymerized oil and lithium stearate, continue stirring under heating until the temperature of the mixture reaches 185 ° C. After that, the heating is stopped and the mixture is allowed to cool while continuing to stir until the temperature of the mixture reaches 60 ° C.
Add grade ammonium clay mineral and mix well. When thoroughly mixed, methyl alcohol and alkylenebisaliphatic monocarboxylic acid amide are added and further thoroughly mixed to promote swelling. Then heating is started and the temperature of the mixture is
Extinguish when 100 degrees C. Add additives such as antioxidants at this point, mix well, and allow to cool to room temperature. Finally, finish processing with a three-stage roll to make the product.

[Examples] Examples of the present invention will be described in detail below. The polyoxypropylene glycol monoether used in this example was Newpol ™ LB-625 manufactured by Sanyo Kasei Co., Ltd., and the viscosity at 40 ° C was about 62 cSt, 1
Clay at 00 degrees C is about 12 cSt and average molecular weight is about 1200. α-olefin polymerized oil is Paol (trademark) manufactured by Bray Oil Company, Inc.
60, the viscosity at about 32 ° C is about 33 cSt, and the clay at 100 ° C is about 6 cSt. Quaternary aluminium salt-containing clay mineral is Organite (trademark) manufactured by Nippon Organic Clay Co., Ltd.
That is, it is an organic bentonite that adsorbs dimethylalkylbenzylammonium. Alkylene bis-aliphatic monocarboxylic acid amide is an organic amide wax manufactured by Ito Oil Co., Ltd. ASA T-300-20AK, ASA D-1
0A, ASA T-75F was used.

Examples 1 to 3 Preparations were made by the following methods according to the formulation shown in Table 1. The polyoxypropylene glycol monoether, the α-olefin polymerized oil, and the lithium stearate are sufficiently stirred and mixed, and then the stirring is continued under heating until the temperature of the mixture reaches 185 ° C.

When the temperature reaches 185 ° C., the heating is stopped and the mixture is allowed to cool while stirring is continued. When the temperature of the mixture reaches 60 ° C., the quaternary ammonium salt-containing clay mineral is added and thoroughly mixed.

After mixing well, methyl alcohol was added and stirred for a while, then alkylenebisaliphatic monocarboxylic acid amide was added and the mixture was further stirred to swell. When the mixture is heated again and the temperature of the mixture reaches 100 ° C, the heating is stopped and 2,6-ditertiarybutyl-4-methylphenol is added and mixed.

The mixture was allowed to cool to room temperature and then finished with a triple roll.

Example 4 Preparation was carried out by the following method according to the formulation shown in Table 1. After adding polyoxypropylene glycol monoether, α-ophthalene polymerized oil and 12-hydroxystearic acid, immediately heat and stir. At 85 to 95 ° C, the aqueous sodium hydroxide solution was put in and the dehydration process was started.

After completion of the dehydration step, heating and stirring are continued, the temperature is raised to 195 ° C., and then the heating is stopped and the stirring is continued while allowing to cool, and when the temperature of the mixture reaches 60 ° C., the quaternary ammonium salt-containing clay mineral is added. The subsequent steps are the same as in Examples 1 to 3.

Comparative Examples 1 to 3 Comparative Example 1 was prepared by the same method as Examples 1 to 3 and Comparative Examples 2 to 3 were prepared by the usual method according to the formulation shown in Table 1.

Table 1 shows the properties of the grease including the durability test of the switch. Here, the durability test of the switch was performed as follows. The stator has a central fixed contact and a sliding fixed contact disposed around the central fixed contact with a 90 degree interval therebetween, and can be rotated. Two movable contacts fixed to the base are arranged above the stator, and the contact surface of one movable contact is always in contact with the central fixed contact of the stator, and the contact portion of the other movable contact is the stator. It comes in contact with and separates from the sliding fixed contact of. Air gaps are provided on both sides of the sliding fixed contact. By rotating the stator, the switch opens and closes, and the durability test of the switch is performed. Copper contacts were used for the contacts. Each grease prepared as described above was applied to the surface of the resin insulator of the stator and the surfaces of the central fixed contact and the sliding fixed contact (application amount: 10
mg / cm ² ). The test conditions are DC24.5V, 120W, switching speed 1cm in order to generate a sufficient electric arc when switching the switch.
/ sec, and under the conditions, a durability test of 50,000 rotations or more was performed to examine the durability of the switch. In tests I and II, mineral-containing nylon 66 resin (kaolin /
Talc) (20/20%) and glass fiber 20% blended unsaturated polyester resin is an evaluation.

(a) When the voltage drop is 50 mV or less, it is A, and when it is more than 50 mV, it is B.

(b) When the amount of contact wear after sliding a 15 mg movable contact 50,000 times is 2.5 mg or less, it is A, and when it is more than that, it is B.

(c) The case where the insulation resistance at 3 mm from the air gap is 10 MΩ or more is A, and the case where it is less than B is B.

(d) The case where the induced voltage is not generated by the chattering of several μ of the contacts is A, and the case where the induced voltage is generated is B.

(e) When the starting torque and the rotation torque at −30 ° C. are 2000 gcm or less and 1000 gcm or less, respectively, A is designated.

As is clear from Table 1, the grease according to this example shows good properties. On the other hand, in each of the comparative examples, the oil separation degree test and the bleeding test are inferior in the bleeding test, and the comparative example 2,
3 was further inferior in the results of (b) and (c) above.

[Effects of the Invention] The polyoxypropylene glycol monoether used as the base oil and the α-olefin polymerized oil are not compatible with each other, and if they are simply mixed, they are separated, and even if they are greased as they are, they are not associated with thickeners. There is a phenomenon that the bad base oil separates.

As a means for solving this, there is a method of using a bentonite-based thickener in combination to suppress the phenomenon that oil is separated from grease.

However, at locations where the operating conditions are more severe, the phenomenon of oil separation from the grease is extremely absent, so a combination of bentonite type thickeners alone is not satisfactory.

The grease composition of the present invention is satisfactory even if it is used in such an extremely difficult place for oil separation, and it reduces the oil separation phenomenon of grease and further satisfies the necessary conditions for sliding contacts. It is a grease composition to be used.

As shown in the examples, by adding alkylenebisaliphatic monocarboxylic acid amide, the bentonite thickener was dispersed well, and as a result, the grease oil separation phenomenon was improved.

The test items demonstrating this result include the oil separation degree test and the blurring test, but as can be seen by comparing Examples 1 to 4 and Comparative Example 1, a large difference is observed and the effect of the present invention is great. Is proven.

In addition, it is a highly advantageous grease composition that can exhibit its general performance as a grease and its performance as a sliding contact grease sufficiently without impairing its performance. Comparative Examples 2 and 3 exemplify polyoxypropylene glycol monoether and α-olefin polymerized oil used alone, but show that the oil separation is large and the performance as a contact cannot be maintained. There is.

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Claims (1)

[Claims] 1. A base oil consisting of 80 to 95 parts by weight of an alkylene oxide-alcohol addition polymerization oligomer and 5 to 20 parts by weight of a chain hydrocarbon oligomer, and an organic lipophilic quaternary ammonium salt-containing clay mineral. A grease composition for improved sliding contact, which comprises 20 parts by weight, 5 to 30 parts by weight of a lithium salt of a higher fatty acid, and 0.2 to 20 parts by weight of an alkylenebis-aliphatic monocarboxylic acid amide.