DE1122655B - Lubricating grease and method of making the same - Google Patents

Description

The invention relates to lubricating greases with increased resistance to heat and mechanical stress and radiation.

The lubricating greases according to the invention are particularly suitable for lubricating moving parts in connection with nuclear reactors, e.g. B. the loading-unloading machine for nuclear waste containers and the drive mechanism for the control rods. It is especially important that greases are used for these uses Do not separate any oil at high temperatures, nor do the nuclear fission material mechanism contaminate harmful deposits and do not thicken under the influence of radiation.

It is already known to thicken oils with a complex of bentonite and a salt of an aliphatic or aromatic amine to give a grease consistency. Typically, such complexes are obtained by first adding an amine, e.g. B. quaternary alkyl or mixed alkyl aryl ammonium salts, with an acid, e.g. B. hydrochloric acid or acetic acid, is converted to the amine salt and this is then added to an aqueous dispersion of the bentonite. The complex obtained in this way is then freed from excess salt by washing, dried and ground to a powder.

The normal method of making such greases is to make a slurry of the bentonite complex in the oil base and to this slurry a polar substance containing oxygen, nitrogen or sulfur, such as acetone or acetone derivatives, e.g. B. methyl ethyl ketone or acetonylacetone, mono- or polyhydric alcohols, e.g. B. ethyl alcohol, diethylene glycol monoethyl ether or ethylene glycol monomethyl ether, propylene carbonate, acetonitrile or phenothiazine. The gel-like mixture thus formed is then homogenized, e.g. B. in a colloid mill, and it forms a rigid fat structure which up to 10 ° / ₀ Bentonitkomplex, based on the total amount, contains from about. 5 The swelling of the bentonite-amine complexes in organic liquids is discussed in a work by John W. Jordan in the journal "Journal of Physical and Colloid Chemistry", Vol. 53, No. 2, 1949, pp. 294-305.

The behavior of liquid lubricants under the influence of ionizing radiation is that, over time, a progressive thickening takes place to a degree which depends on the nature of the liquid lubricant and the intensity of the radiation. The oils described above, thickened with bentonite-amine complexes, are opposed to lubricating grease, depending on the amount of bentonite used for the production of grease
and methods of making the same

Applicant:

Esso Research and Engineering Company,
Elizabeth, NJ (V. St. A.)

Representative: E. Maemecke, Berlin-Lichterfelde West,

and Dr. W. Kühl, Hamburg 36, Esplanade 36 a,

Patent attorneys

Claimed priority:
Great Britain dated April 11, 1960 (No. 12 803)

Arthur L. Morris and Mervyn R. White,

Didcot, Berkshire (UK),

have been named as inventors

resistant to the thickening influence of radiation. This can be seen from the drawing, in which the change in ASTM micropenetration of a mineral oil with a viscosity of 200 SUS at 98.9 ° C and a viscosity index of 80 and a bentonite-amine complex (complex of bentonite and the didodecyldimethylammonium group ) produced lubricating grease is shown when irradiated with 10 ⁹ rad / 3 rays. Conventional bentonite-amine complex thickened lubricating greases, ie those containing less than 10 percent by weight of the bentonite-amine complex, show very strong softening when exposed to radiation and are unsuitable for use in nuclear reactors. However, if the amount of thickener is increased above 10%, then using normal methods of dispersing the complex with acetone or similar dispersants, the fat becomes too stiff for useful application. Another limitation on the use of polar compounds as dispersants is that when the fat is used

109 787/370

high temperatures, as they occur in nuclear reactors, the dispersants volatilize and are driven off in the form of vapors.

Lubricating greases with improved radiation resistance can be prepared by thickening an oil base with more than 10 percent by weight of the bentonite-amine complex described above and thereby the complex without the aid of a polar compound by heating the mixture of oil base and complex to a temperature of about 102 to 121 ⁰ C and subsequent homogenization of the mixture until a grease-like gel structure is formed. This process leads to a lubricating grease with satisfactory mechanical properties; However, the lubricating greases have an unstable structure at higher temperatures after exposure to radiation and consequently poor lubricity. This emerges from the following tempter:

Two greases, grease A and grease B are prepared by thickening a mineral oil of a viscosity of 200 SUS at 98.9 ⁰ C and a viscosity index of 80 with a commercially available amine bentonite complex (complex of bentonite and the Didodecyldimethylammoniumgnjppe) . Fat A contains 11.6% by weight of the complex dispersed with 2.5% acetone; fat B contains 17 percent by weight of the complex, dispersed by 1 hour heating to 102 ⁰ C, allowed to cool, with stirring to 66 ° C and homogenising in a Morehouse mill mm with a gap width of 0.025.

The thermal and mechanical resistance of these greases are in a ball bearing device examined according to the following procedure:

The ball bearing device consists of a steel shaft, which with the help of three axial bearings in one Steel bushing is mounted. The ball bearings to be tested are located inside the socket at both ends and a blind roller bearing, while another ball bearing is mounted outside the bushing and serves to transfer the thrust load. The inside of the bearing to be examined is marked with equipped with a "Nilos" seal, which is perforated to prevent the flow of carbon dioxide in to allow the fat in. The blind camp will

ίο Equipped with a standard PTFE seal. the An electric motor running at constant speed has an elastic shaft Coupling driven at a speed of 1440 rpm, and a thrust load of 45 kg is brought into action with the help of a spring. This causes the ball bearing to be examined prevented from sliding. The socket is placed under a carbon dioxide pressure of 0.13 to 0.2 atmospheres, whereby due to the perforations in the seal, a flow of the gas with a low flow velocity takes place. An electric heater is used to heat the bearing to be examined intended. Before running a test, the bearing is completely filled with grease, and excess Grease is removed by hand by quickly turning the bearing. After uninterrupted 100 hours of operation will determine the condition of the bearing and the degree of hardening of the grease noted, with any oil leakage on the open side of the bearing particular Attention is paid.

The radiation to which the fats are exposed comes from a linear 4-MEV accelerator, and ASTM penetration is used as a measure of the change caused by a given radiation dose (in mm / 10) of the fat before and after irradiation. The results can be found in Table I.

Table I.

Fat A

Fat B

Bentonite complex content

Resistance to radiation

Penetration before irradiation, mm / 10

Penetration after irradiation with 1 · 10 ⁸ rad, mm / 10 Penetration after irradiation with 1 · 10 * rad, mm / 10

Structural stability
(100 hours at 20O ⁰ C)

before irradiation

Oil leakage

Condition of the fat

after irradiation with 1 · 10 * rad

Oil leakage

Condition of the fat

From Table I it can be seen that the radiation resistance and the structural stability before Radiation are considerably better for fat B than for the fat A, however, that the structural stability at high temperature after irradiation is not essential is improved.

247
270
310

strong

Surface hardening
and local thickening

very strong

Surface hardening
and local thickening

17 ° / o

266

280 292

none

weakness

Surface hardening

moderate

Surface hardening and local thickening

It has now been found that lubricating greases based on an oil, which with 10 percent by weight or more, based on the total mass, is thickened on a bentonite-amine complex, improved mechanical Have resistance and structural stability, if they also have carbon black in terms of weight

Proportions in the range from 1: 1 to 1:20, preferably from 1:10 to 1:15, based on the bentonite-amine complex, contain. The improvement in the structural stability after irradiation is special pronounced with greases that are greater than about 13 percent by weight, e.g. B. 13 to 20 percent by weight, Contains bentonite complex.

The lubricating greases according to the invention preferably have a total content of bentonite complex + carbon black from 10.5 to 25 percent by weight, based on the total mass, of which 0.5 to 5%, also based account for the total mass, for the soot.

Any organic oil base can be used to produce the lubricating greases according to the invention. Mineral lubricating oils are particularly preferred for lubricating nuclear reactors; however, the lubricating greases according to the invention can also be produced from synthetic oils, e.g. B. from esters such as C ₆ - to C ₁₈ -esters of organic mono- or dicarboxylic acids or complex esters, which are z. B. can derive from dicarboxylic acids, glycols or polyglycols and monohydric alcohols, alkylated benzenes or mixtures of these substances.

The lubricating greases according to the invention can be produced by using the bentonite-amine complex stirred with the oil base at a higher temperature, e.g. B. by bringing the mixture to about 99 heated to 121 ° C. The carbon black is then added and the mixture is stirred further, bringing it to about Let 66 ° C cool down. The mixture is then ground to a fat consistency, e.g. B. in a colloid mill.

The lubricating greases can, however, also by known methods, as described above, with the aid of a polar material if it is not too stiff for the intended use will.

The following examples illustrate the technical progress achieved by the invention:

Fat C is prepared according to the invention by adding 11.6 percent by weight of a commercially available Bentonite amine complex (complex of bentonite and the didodecyldimethylammonium group) blends with 84.4% of a mineral oil with a viscosity index of 80. The mixture is stirred mixed with 2.5% acetone and then stirred for a further 20 minutes. 1.5% acetylene black is slowly added to this and the mixture is stirred for a further 45 minutes. The finished mixture is made in a Morehouse mill grind a gap of 0.025 mm.

Grease D according to the invention is prepared by stirring 17% of the bentonite-amine complex mentioned in the previous paragraph with the oil base used for lubricating grease C for 10 minutes and heating the mixture to 102 ° C. for 1 hour. Then 1.2% acetylene black is added with stirring and the mixture is allowed to cool ^{to 66 ° C. with stirring.} The mixture is then allowed to cool further to room temperature and processed to a fat consistency in a Morehouse mill with a gap width of 0.076 mm.

Fats C, D and E are tested using the same procedure as Fats A and B to give the results shown in Table II.

Table II

Fat C. Fat D Fat E. Bentonite complex content
soot 10.4%
1.2%
1: 9.6
257
278
280
moderate
surfaces
hardening
and local
thickening
strong
surfaces
hardening
and local
thickening 15.8%
1.2%
1: 14.2
280
285
287
none
unchanged
none
unchanged 13.6%
3.4%
1: 4
301
313
320
none
unchanged
none
enough Ratio of soot to bentonite
Radiation Resistance
Penetration before irradiation, mm / 10
Penetration after irradiation with 1 · 10 ⁸ rad, mm / 10
Penetration after irradiation at 1 x 10 x rad, mm / 10
Structural stability
000 hours at 20O ⁰ C)
before irradiation
Oil leakage Condition of the grease
after irradiation
Oil leakage Condition of the grease

When comparing the greases C and D with the greases A to a certain extent, the structure

and B it is noticed that the addition of a small 65 resistance under mechanical stress

Amount of soot for fat A (which results in fat C) of the irradiation is improved. The addition of soot to the

the resistance to thickening under the fat B, which is a relatively large proportion

The effect of radiation is considerably improved and contains the bentonite thickener (whereby the

Fat D) leads to a substantial improvement the structural stability after irradiation.

Grease E shows that there is some improvement in texture before or after irradiation the lubricating greases according to the invention is achieved when the ratio of soot to bentonite-aroin complex is relatively high.

Claims (6)

PATENT CLAIMS: IO 1. Lubricating grease based on an oil which is thickened with a bentonite-amine complex in an amount of at least 10 percent by weight, based on the total amount, characterized in that it contains a small amount of carbon black and the weight ratio of carbon black to Bentonite amine complex is in the range from 1: 1 to 1:20. 2. Lubricating grease according to claim 1, characterized in that the total content of bentonite-amine complex and carbon black in the range from 10.5 to 25% based on the total mass, of which 0.5 to 5 ° / o> also based on the total mass, account for the soot. 3. Lubricating grease according to claim 1 or 2, characterized in that it contains 13 to 20 percent by weight, based on the total mass, the bentonite-amine complex is thickened. 4. Lubricating grease according to claim 1 to 3, characterized in that the weight ratio of Carbon black to bentonite amine complex is in the range from 1:10 to 1:15. 5. A method for the production of lubricating greases according to claim 1 to 4, characterized in that that the bentonite-amine complex is mixed with the oil base at a higher temperature, then the soot added and then the mixture is cooled and ground to the desired fat consistency will. 6. The method according to claim 5, characterized in that the bentonite-amine complex with the oil base at a temperature in the range of 99 to 121 ⁰ C is stirred. 1 sheet of drawings © 109 787/370 1.