DE2320994B2 - Electrical contact grease - Google Patents

Description

The invention relates to an electrical contact grease, i. H. on a grease for electrical contacts that especially in the field of sliding or sliding contacts of electrical machines and devices is applied.

Conventional electrical contacts, e.g. B. in televisions and radios, suffer contact failures and are against disturbances such. B. sound interference or noise and dropouts, etc., sensitive.

These disturbances are reduced to a certain extent by the use of electrical contact greases prevented. However, conventional greases for electrical contact have not yet behaved completely satisfactory, which can be attributed to the intricate nature of the phenomenon of electrical contact is.

Contact failure is generally caused by oxidation, sulfurization and abrasion of contact metal surfaces and caused by sludge formed by oxidation and polymerization of grease used for contact. The task of the contact grease is therefore an oxidation, a sulfurization and an abrasion of contact metals to prevent disturbances so as to keep the electrical contact resistance constant to prevent and to extend the service life of the electrical contact.

bs> iat therefore particularly desirable that the electric Vontaktfett has a low contact resistance that the contact resistance in particular does not increases and that the electrical contact grease protects the contact material against abrasion.

As has emerged from comparative tests, those which have become known from DT-AS 20 02 333 show Electrical contact greases have significant disadvantages because they have a high initial resistance and furthermore, the contact resistance is unstable.

Using the DT-AS 20 02 333 samples A, B and C of the electrical contact grease from the DT-AS 20 02 333 known composition produced.

Mineral oil viscosity: 6OcSt Ba stearate Ba stearate Ba stearate Weight mile (dynaasiscbs toughness) Li stearate Li stearate Li stearate in% 5 AnUinpunkt: Al stearate Al stearate Al stearate 74.7 108.5 ⁰ C Polychlorotriphenyl Polychlorotriphenyl Hexachlorodiphenyl 4,4'-tetramethyldiaminodiphenyl Na salt det dinonylnaphthalene 4,4'-methylene-bis- (2,6-di-tert-butyl- 8.0 methane sulfonate ohenol) 5.0 IO Sorbitan monooleate 2,6-di-tert-butylphenol Sorbitan monooleate 2.0 Sample B Sample C 10.0 Mineral oil viscosity: 118cSt Mineral oil viscosity: 80.2cSt 0.1 (dynamic toughness) ! dynamic toughness) «5 Aniline point: Aniline point: 0.2 113.2 ° C 104.0 ⁰ C ZO Parts by weight in % 73.3 25th 6.0 4.0 2.0 14.0 3 ° 0.2 0.5 35 Parts by weight in % 40 69.8 10.0 6.0 45 2.0 11.0 0.2 50 1.0

The results of comparing these samples with the electrical contact greases of the invention are shown in Table A and FIG.

Table A. Sample of fat Con
tact
pressure
(P) Contact rivet
matertal Con-
takl-
rivet-
ahrieb test
No. (Thickness <g! (mm) example 1
Example 2
Example 3 90
90
90 Ag
Ag
Ag 0.032
0.027
0.024 1
2
3

continuation

Sample of fat

Kon- Konlaklnieitakt- material pressure
Π »)

(G)

Contact abrasion

(Thickness) (mm)

Example 4
Example 5
Silicone grease
Example 4
Example 4
Example 4

10 Example 4

Example 4
Sample A
Sample B
Sample C

90 Ag 0.020

90 Ag 0.022

90 Ag 0.060

15 Ag 0.007

350 Ag 0.052

90 Ag-Cu 0.018 (90 - JO)

90 Au-Ag-Pt 0.017

(69-21-6)

90 nickel silver 0.014

90 Ag 0.043

90 Ag 0.032

90 Ag 0.038

Furthermore, the following table clearly shows the differences between the invention and the known Contact grease of the DT-AS 2002 333.

DT-AS 2ΠΟ2 333

As a thickener
serves a mixture of
Ba soap .... 40 to 65%
Li soap .... 25 to 40%
Al soap .... 10 to 20%

Nine different
chlorinated aromatic
Hydrocarbons
are used

As an antioxidant
serve 11 different
Compounds including phenol and amino compounds

Serves as the base oil
exclusively
paraffinic mineral oil

No use of

Polyoxypropylene butyl

invention

The only thickening agent used is Li stearate

No chlorinated hydrocarbons are used

Only certain amino compounds serve as antioxidants

Di-2-ethylhexyl sebacate is used as the base oil

0.5 to 40.0% polyoxypropylene butyl ether is used

The object of the invention is to provide a contact grease available that the wear and tear of the electrical Able to prevent sliding contact. Furthermore, the contact grease should keep the contact resistance constant and thereby prevent malfunctions in electrical contact.

According to the invention the object is achieved in that the electrical contact grease to be used from

at di-2-ethylhexyl sebacate as the main ingredient,

b) 0.5 to 40.0 percent by weight of polyoxypropylene butyl ether JC ₄ H ₉ O (CH ₃ - CH - CH ₂ O) _n H),

c) 0.2 to 5.0 percent by weight of an amino compound as an antioxidant and

d) 9 to 18 percent by weight lithium stearate

consists.

One embodiment of the invention contains a polyoxypropylene butyl ether with an average of 4 to

ίο 50 moles of propylene oxide grapes.

Contains another embodiment of the invention as an antioxidant an N, N'-di-sec-butyl-paraphenylenediamine, N, N, N ', N'-tetramethyl-4,4'-diaminodiphenylmethane or an N-phenyl-a-naphthylamine.

The new contact grease of the invention prevents an electrical contact from failing and leads to a satisfactory contact effect for a longer period, especially if it is an electrical one Contact is applied, which consists of a combination of a contact rivet from a platinum. Gold, silver, copper or the alloys thereof with another contact plate made of nickel, or nickel-silver. Nickel is often used to fill a print circuit or a Contact metal because of its good chemical resistance and its mechanical properties, even if its specific electrical resistance is comparatively higher is.

The di-2-ethylhexyl sebacate mentioned here includes commercially available material and also pure material.

A contact grease according to the invention contains polyoxypropylene butyl ether (POPBE). It's beneficial. if the polyoxypropylene butyl ether on average 4 to 50 moles of propylene oxide groups (PO groups) contains.

Polyoxypropylene butyl ether, in which the PO group makes up less than 4 moles, results in a contact grease, which has poor anti-wear ability and a Polyoxypropylene butyl ether, in which the PO group makes up over 50 moles, also leads to one Contact grease that has a low wear resistance.

When the polyoxypropylene butyl ether is present in an amount less than 0.5% by weight, the wear resistance is poor.
If the amount of polyoxypropylene butyl ether is more than 40 percent by weight, the electrical contact resistance becomes inconsistent.

The contact grease of the invention also contains an amino compound as an antioxidant; h .. at least a compound of the from N, N'-di-sec-butyl-paraphenylenediamine, N.N.N'.N-tetramethyl-4,4'-diaminodiphenylmethane (tetrabase) and N-phenyl-ii-naphthylamine existing group.

If the amino compound is present in an amount of <0.2 percent by weight, it is difficult to

6c to keep the electrical contact resistance constant. When the amount reaches an amount> 5.0% by weight, the electrical contact resistance becomes higher.
The amino compound used as an antioxidant serves not only to prevent the polyoxypropylene butyl ether from being oxidized, but also to reduce the wear of the contact metals and make the contact resistance constant.

The contact grease of the invention also contains lithium stearate. To the one under consideration here Lithium stearate includes commercially available material and pure material.

If the lithium stearate is present in an amount <9 percent by weight, the fat has poor physical resistance. When the amount of lithium stearate is more than 18 percent by weight matters, the wear resistance becomes weaker.

Other additives are preferably added to the contact grease of the invention, such as. B. rust inhibitors, Antisulfurizing agents and the like.

According to the invention a mixture of the di-2-äthylhexylsebacat, the Polyoxypropylenbutyläther, the amino compound and the lithium stearate is mentioned with or without a rust inhibitor and Antisulfurierungsmittel at 210 to about 230 ⁰ C, so that a homogeneous liquid is obtained.

The mixture is rapidly cooled, ground by an ordinary method, and then reduced Subjected to pressure to remove air and foam.

The fats obtained are smooth and buttery in texture and excellent in quality > mechanical strength and heat resistance.

The invention is described in more detail in the following examples. In the examples "g" means gram.

example 1

A mixture of 86.2 g of di-2-ethylhexyl sebacate, 1.0 g of polyoxypropylene butyl ether with 5.0 moles of PO groups, 0.3 g of tetrabase and 12.5 g of lithium stearate are heated at about 220 ° C.

After the mixture has been homogenized, it is quickly cooled to room temperature and ground in a three-roll mill. Then residual foam present in the fat is reduced under reduced Pressure removed. The fat obtained is stable and has a pour point of 201.0 C. The Grease is applied to an electrical contact. The fat effect is in Example 1 in Table 1 and indicated in the figure.

45

Example 2

A mixture of 77.3 g of di-2-ethylhexyl sebacate. 8.2 g of polyoxypropylene butyl ether with 15.2 mol of PO groups. 1.0 g of Ν, Ν'-di-sec ^ butyl-paraphenylenedi-amine and 13.5 g of lithium stearate are heated to 215 C.

The mixture obtained is treated in the same manner as in Example 1. The test is carried out as in Example 1 and the result obtained is shown in Table I and in the figure.

Example 3

A mixture of 784 g of di-2-ethyihexyl sebacate

Polyoxypropylenbutyläther with 474 moles of PO groups, 1.8 g of tetra base and 14.2 g lithium stearate is heated at 220 ⁰ C

The mixture obtained is treated in the same manner as in Example 1. The test is carried out as in Example 1 and the result obtained is shown in Table I and in the Figure - Example 4

A mixture of 48.7 g of di-2-ethylhexyl sebacate, 38.5 g of polyoxypropylene butyl ether with 23.0 mol of PO groups, 1.5 g of Ν, Ν-di-sec-butyl-paraphenylenediamine and 11.3g lithium stearate is made at 230 ° C warmed up.

The mixture obtained is treated in the same manner as in Example 1. The test will be like carried out in Example 1, and the result obtained is shown in Table I and in the figure reproduced.

Example 5

A mixture of 65.0 g of di-2-ethylhexyl sebacate, 21.0 g of polyoxypropylene butyl ether with 35.2 mol of PO groups, 3.5 g of N-phenyl-a-naphthylamine and 10.5 g Lithium stearate is heated at 210 ° C.

The mixture obtained is treated in the same manner as in Example 1. The test will be like carried out in Example 1, and the result obtained is shown in Table I and in the figure reproduced.

In Table I are the test results for wear resistance of the fats according to Examples 1 to 5 and a commercially available conventional one In bold (comparison).

The test was carried out in detail as follows:

The greases were applied to the sliding contact, which consists of a combination of movable Contact rivet and fixed contact plate existed.

The material used for the fixed contact plate is nickel.

The radius of curvature on the upper side of the movable contact rivet is 2 mm. The rivet is there from at least one member of the platinum. Gold, silver, copper and their alloys existing group.

The wear of the contact rivet was shown in the form of the decrease in thickness on the upper side of the rivet 50,000 times sanding at a sanding speed of 8 cm / s and a sanding distance of 4 cm measured.

The value for the electrical contact resistance changes with the grinding process, whereby the Peak value is of little importance for the contact resistance.

The energy E that was consumed at the contact in a given time was determined.

The energy is expressed as follows:

= J

1 = measured contact current,
t = measured time, Rc = electrical contact resistance d

In the given case, the following conditions exist:

/ = 500 mA,

t = 1 s.

The numerals 1 to 11 correspond in the figure the relevant digits in Table I.

In general it can be said that the difference between the contact resistance before and after the grinding process should not be great in order to be effectively suited as an electrical contact to be able to be.

It can be clearly seen from the figure that the fat of the invention has a small difference between the

Has contact resistance at the beginning of the grinding process and after 50,000 grinding processes.

Thus, the grease of the invention results in an electrical contact with a constant specific Contact resistance, which completely prevents the generation of noise and extends the service life of electrical contact is extended.

Tabel I. Con- Contact rivet Con- Tesi Fur test tact- material tact- Mr. pressure- rivet- loading abrasion burden (Thickness) (G) (mm) 90 Ag 0.032 1 example 1 90 Ag 0.027 2 Example 2 90 Ag 0.024 3 Example 3 90 Ag 0.020 4th Example 4 90 Ag 0.022 5 Example 5 90 Ag 0.060 6th Silicone grease 15th Ag 0.007 7th Example 4 350 Ag 0.052 8th Example 4 90 Ag — Cu 0.018 9 Example 4 (90-10) 90 Au-Ag-Pt 0.017 10 Example 4 (69-21-6) 90 Nod! —Silver 0.014 11 Example 4 1 sheet of drawings For this

$ 09536/391

Claims (3)

Sample A Patent claims: L electrical contact grease, characterized that it is off a) Di-2-ethylhexyl sebaeate as the main component, b) 0.5 to 40.0 percent by weight of polyoxypropylene butyl ether, c) 0.2 to 5.0 percent by weight of an amino compound as an antioxidant and d) 9 to 18 percent by weight lithium stearate consists. 2. Contact grease according to claim 1, characterized in that that it is a polyoxypropylene butyl ether with an average of 4 to 50 moles of propylene oxide groups contains 3. Contact grease according to spoke 1, characterized in that it is an N, N'-Disek as an antioxidant. - butyl - paraphenylenediamine, Ν, Ν, Ν ', Ν'-tetramethyl-4,4'-diaminodiphenylmethane or contains an N-phenyl-a-naphthylamine.