EP0902828A1

EP0902828A1 - Lubricating grease compositions

Info

Publication number: EP0902828A1
Application number: EP97925984A
Authority: EP
Inventors: Dirk Loderer; Dieter Sohn; Herbert Kardinal
Original assignee: Klueber Lubrication Muenchen GmbH and Co KG
Current assignee: Klueber Lubrication Muenchen GmbH and Co KG
Priority date: 1996-06-07
Filing date: 1997-06-05
Publication date: 1999-03-24
Anticipated expiration: 2017-06-05
Also published as: HK1018959A1; BG102993A; AU734890B2; CA2257368C; EP0902828B1; US6265362B1; BR9709645A; WO1997047710A1; DK0902828T3; BG63604B1; CA2257368A1; AU3093997A; JP2000514105A; ES2159867T3; JP4098831B2; ATE204601T1; DE19622906A1; DE59704374D1; TW509720B

Abstract

A lubricating grease composition that is a mixture of(a) a hydrocarbon-based oil,(b) a perfluoro-polyalkyl ether oil of the formula in whichA' is -CF3, -C2F5, -C3F7, or -CF2T where T is H or Cl,A'' is A' or -CF3, C2F5, -C3F7, or -CF2T, where T is H or Cl1 andv, w, x, y and z are whole numbers >=0,(c) a dicarbamide as a thickening agent,(d) typical additives and(e) organic and inorganic solid lubricants.A process for the production of the lubricating grease composition is also provided.

Description

Grease compositions

description

The invention relates to grease compositions made from a base oil mixture which consists of a hydrocarbon oil and a perfluorinated polyalkyl ether oil and a small proportion of thickener based on a diurea compound and conventional additives which are used at temperatures of more than 180 ° C. to 250 ° C. have a particularly noise-reducing behavior, and a method for producing these grease compositions.

The development of new lubricants must go hand in hand with the general further development of technology, which places new and higher demands on the lubricant compositions. The known lubricants based on mineral or synthetic oils are no longer able to meet these requirements.

Lubricants are used in vehicle technology, conveyor technology, mechanical engineering, office technology as well as in industrial plants and machines, but also in the areas of household machines and consumer electronics.

In roller bearings, the lubricants ensure that a separating, load-transmitting lubricating film is built up between parts sliding or rolling on one another. This ensures that the metallic surfaces are not touch and therefore no wear occurs. The lubricants must therefore meet various requirements, including:

extreme operating conditions such as very high and very low speeds and loads, high temperatures which are caused by high speeds and loads or by external heating, very low temperatures by low self-heating of the bearings in a cold environment or by intensive heat dissipation to the cold environment , special requirements of the user regarding the running properties, eg low friction, low noise, the requirement for extremely long running times without relubrication in the meantime, unfavorable ambient conditions and inadequate sealing of the bearing point, and

Force effect on the lubricant, e.g. Centrifugal force, gravity, vibrations.

In addition to the upper service temperature in accordance with DIN 51825, the noise characteristics of the lubricant are important parameters for the long service life of a grease-lubricated rolling bearing in the high temperature range. A lubricating grease can stimulate vibrations in the rolling bearing during partial rotation (rollover, walking), which are "lubricant noises" in the frequency bands 300 to 1800 Hz and High 1800 to 10000 Hz, compared to the bearing noises in the frequency band Low at 50 to 300 Hz. The lubricant noise is superimposed by the noise peaks which arise when hard particles are rolled over by the rolling elements in the form of shock pulses on the bearing ring. The noise behavior is assessed according to the SKF-Bequiet method, which is based on the statistical evaluation of the noise peaks and the assignment to noise classes BQ1 to BQ4. With increasing value In the noise class, the noise behavior and the service life of the rolling bearing deteriorate (H. Werries, E. Paland, FVA study on the subject of "low-noise lubricating grease", University of Hanover 1994). Thus, 100% noise class BQ1 characterizes very good, and low percentages only in noise class BQ4 very bad noise behavior. The better the noise behavior of a lubricating grease, the lower the vibrations of the bearing which are forced by the lubricant. This is synonymous with a lower load on the rolling bearing and a longer service life of the bearing.

From US-A 5 512 188 a lubricant composition is known which comprises a base oil such as trimethylolpropane pelargonate, pentaerythritol pelargonate, polyphenyl ether, perfluoroalkyl ether and mixtures thereof, and a thickener such as a di- or polyurea. The diurea can be made from a diisocyanate and an amine such as octylamine and aniline. Furthermore, the lubricant composition can contain boron nitride or polytetrafluoroethylene (solid lubricant) and additives.

European patent application EP-A 94 118 667.8 describes lubricating greases which are based on a mineral or a synthetic oil based on hydrocarbons, thickened with a perfluorinated polyalkyl ether with an organic or an inorganic thickener. The weight ratios of lubricating oil and perfluorinated polyalkyl ether / thickener are in the range from 97: 3 to 80:20 and the ratio of lubricating oil / perfluorinated polyalkyl ether is in the range from 95: 5 to 60:40. These lubricating greases extend the operating time at a service temperature of 170 ° C to 175 ° C when the perfluorinated polyalkyl ether component is admixed. Low-noise lubricating greases are known from US Pat. No. 5,145,591, which are based on thermally stable polyphenyl ethers, alkylated phenyl ethers, polyol esters and aromatic carboxylic acids, which are compressed with 5 to 30% by weight of di- and / or polyureas, which are used in the above Operating temperatures of 180 ° C according to DIN 51 825 can be used. For use temperatures above 180 ° C, greases must be used which are based entirely on perfluorinated polyalkyl ethers thickened with PTFE, inorganic thickeners such as bentonites, aerosols or metal soaps or metal complex soaps , are used.

The aim of the invention is to provide a lubricant composition which meets the above-mentioned requirements, can be used in particular under high temperature conditions and has very good noise behavior, and has long running times and essentially no wear and tear on the rolling bearing.

For this purpose, according to the invention, a lubricating grease composition consisting of a mixture of an oil based on hydrocarbons, a perfluorinated polyalkyl ether oil and a diurea as a thickening agent and conventional additives is provided.

The hydrocarbon-based oil is made from an ester of an aromatic di-, tri- or tetracarboxylic acid, with one or a mixture of C ₇ to C ₂₂ alcohols, a polyphenyl ether or alkylated polyphenyether, an ester of trimethylolopropane, pentaerythritol or dipentaerythritol aliphatic C ₇ to C ₂₂ carboxylic acids, C ₁₈ dimeric acid esters with C ₇ to C ₂₂ alcohols, complex esters, prepared as individual components or in any mixture. The perfluorinated polyalkyl ethers of the grease compositions according to the invention have the general formula

A '- (0-CF ₂ ) _v - (0-C ₂ F ₄ ) _w - (0-C ₃ F ₆ ) _x - (0-C ₄ F _β ) _y - (0-CF ₂ CF (CF ₃ )).-0-A ''

in which A 'is -CF ₃ , -C ₂ F ₅ , -C ₃ F ₇ , -CF ₂ T, where TH or Cl corresponds,

A '' is the same as A 'or is different -CF ₃ , -C ₂ F ₅ , -C ₃ F ₇ , -CF ₂ T, where TH corresponds to Cl, and v, w, x, y and z are integers ≥ O are.

Preferred chain building blocks are

- (CF (CF ₃ ) CF ₂ 0) _-,

- (CF (CF ₃ ) CF ₂ 0) _z - (CF ₂ 0) _v , where z / v is approximately 40/1,

- (CF ₂ CF ₂ 0) _w - (CF ₂ o) _v , where w / v is approx. 3/2 and

- (CF ₂ CF ₂ 0) _w - (CF ₂ 0) _v , where w / v is approximately 2/3.

The perfluorinated polyalkyletherols which are preferably used are thermally stable oils with low evaporation rates at 200 ° C., such as commercially available aflunox, fomblin, crytox or demnum oils which are used in the grease compositions according to the invention. The grease compositions that meet the requirements in the high temperature range can only be produced with perfluorinated polyalkyl ethers.

The thickeners are the reaction product of a diisocyanate, preferably 2,4-diisocyanate-toluene, 2,6-diisocyanatotoluene, 4-4 '-diisocyanate-diphenylmethane, 4-4'-diisocyanate-diphenyl, 4,4' - Diisocyanato-3, 3 '- -dimethyldiphenyl, 4,4'-diisocyanato-3, 3' -dimethyldiphenyl-methane, individually or in a mixture and an amine of the general formula (H ₂ N) _X R, where x = 1 and R is an alkyl or alkylene radical with 6 to 22 carbon atoms or an aryl radical with 6 to 12 carbon atoms, individually or in a mixture. In addition, the lubricating grease compositions according to the invention contain customary additives against corrosion, oxidation and for protection against metal influences, which act as chelate compounds, radical scavengers, UV converters, reaction layer formers and the like.

The lubricating grease compositions according to the invention are mixed in a ratio of greater than 60/40 of hydrocarbon-based oil and perfluorinated polyalkyl ether oil and thickened with 5 to 30% by weight of the diurea compound and contain up to 10% by weight of additives and / or up to 10% by weight of organic or inorganic solid lubricants. These solid lubricants can e.g. Polyimides, PTFE, graphite, metal oxides, boron nitride, molybdenum disulfide or phosphates.

In the case of these composite greases, the viscosity of the hydrocarbon-based oil is in the range from 100 to 500 mm ^a / s and that of the perfluorinated polyalkyl ether oil is 10 to 1500 mm ² / s.

In addition, the grease compositions have dropping points according to DIN ISO 2176 of> 240 ° C and are suitable according to DIN 51825 for upper service temperatures up to 250 ° C.

The grease compositions according to the invention are obtained either by mixing the hydrocarbon-based oil thickened with diurea with the perfluorinated polyalkyl ether oil and then homogenizing it via a high-pressure homogenizer and / or three-roller mill, or by mixing the hydrocarbon-based oil with the perfluorinated polyalkyl ether oil and is thickened in this mixture by synthesis of the diurea compound and then homogenized using a high-pressure homogenizer and / or three-roll mill. The invention is illustrated by the following examples.

example

Example 1 (Bl)

In 700 g of a dialkylphenyl ether oil which has alkyl radicals with 8 carbon atoms, 120.8 g of a mixture of 2,4- and 2,6-tolylene diisocyanate are reacted with 129.9 g of aniline. After the exothermic reaction is complete, the brew is heated to 160 ° C. During the cooling, 20 g of a commercially available antioxidant, 20 g of a commercially available wear protection additive and 10 g of a commercially available corrosion protection agent are added. Then 667 g of a perfluorinated polyalkyl ether with a viscosity of 200 mm ² / s are added at 40 ° C. The fat is homogenized by a single high-pressure homogenization and subsequent rolling on a three-roll mill. In this way, a grease of NLGI class 2 according to DIN ISO 2137 is obtained. This grease obtained in this way is tested on a noise test bench. A particularly low-noise behavior was measured compared to commercially available lubricating greases.

Example 2 (B2)

In a two-phase mixture of 800 g of ester oil, consisting of an ester of trimellitic acid and an alcohol mixture of C _B and C ₁₀ alcohols, with 1000 g of perfluorinated polyalkylene ether with a viscosity of 400 mm ² / s at 40 ° C. 78 , 7 g of diphenylmethane isocyanate reacted with 81.3 g of octylamine in the same manner as in Example 1, provided with 40 g of commercially available additives and homogenized by repeated rolling on a three-roll mill. In this way, a grease of NLGI class 2 according to DIN ISO 2137 with particularly low-noise behavior is obtained. Example 3 (B3)

The grease composition was prepared analogously to Example 2, with the exception that the oil mixture presented consisted of 800 g of ester oil and 800 g of perfluorinated polyalkyl ether.

In this way, a grease of NLGI class 2 according to DIN ISO 2137 with particularly low-noise behavior is obtained.

Example 4 (BL)

The grease composition was prepared analogously to Example 2, with the exception that the oil mixture presented consisted of 800 g of ester oil and 500 g of perfluorinated polyalkyl ether.

Example 5 (B5)

The grease composition was prepared analogously to Example 2, with the exception that the oil mixture presented consisted of 800 g of ester oil and 200 g of perfluorinated polyalkyl ether.

Example 6 (B6)

The grease composition was prepared as in Example 2, with the exception that the 800 g of espresso no perfluorinated polyalkyl ether was added. In this way, a grease of NLGI class 2 according to DIN ISO 2137 with particularly low-noise behavior is obtained.

Example 7 (B7)

The grease composition of Example 6 was placed her¬, with the exception that instead of 800 g Esteröl from trimellitic acid and C ₈ - and C ₁₀ alcohols Esteröl 800 g of pyromellitic acid and C ₈ - and C were used ₁₀ alcohols.

Example 8 (B8; comparative example)

Commercial product made from perfluorinated polyalkyl ether (PFPE) thickened with polytetrafluoroethylene (PTFE).

The following tables show the properties of the lubricants of Examples 1 to 8.

Table 1 shows the measurement results with regard to the noise test of the grease compositions according to DIN ISO 2137 prepared according to Examples 1 to 8. Table 1

Grease Bl B2 B3 B4 B5 B6 B6 g7 B8 FAG FE-9, DIN T2 test temperature

(° C) 220 220 220 220 220 200 180 200 240

(A, 6000, 1500) term

L ₅₀ Weinbull 156 210 142 81 56 20 530 113 83 NLGI class 2 2 2 2 2 2 2 2 2

(DIN ISO 2176) Dropping point> 240> 240> 240> 240> 240> 240> 240 approx. 170

DIN ISO 2176) Noise class SFK-approved

% BQ1 39 94 89 90 85 88 99 0

% BQ2 82 98 98 98 97 96 100 5

Table 2 shows the weight ratios of the grease compositions of Examples 1 to 8.

Table 2

Grease Bl B2 B3 B4 B5 B6 B7 B8

% By weight CH-based lubricating oil 42 40 44.4 53.4 66.6 80 80 0

% By weight of consistency agents and additives 18 10 11.2 13, 3 16, 7 20 20 20

% By weight perfluorinated polyalkyl ether oil 40 50 44.4 33.3 16.7 0 0 80 Table 3 shows the mixing ratios of hydrocarbon-based oil and perfluorinated polyalkyl ether oil.

Table 3

Grease Bl B2 B3 B4 B5 B6 B7 B8

% By weight CH-based lubricating oil 51.2 44.4 50 61.6 80 100 100 0

% By weight perfluorinated polyalkyl ether oil 48.8 55.6 50 38.4 20 0 0 100

Tables 1 and 2 show that the lubricating grease B6 based on an ester oil thickened with diurea exceeds the requirements for an upper operating temperature of 180 ° C according to DIN 51825 by a factor of 5, but the criterion of an L ₅₀ running time of at least 100 hours according to DIN 51825 on the FAG FE-9 roller bearing testing machine at 200 ° C is not nearly fulfilled. The criterion of an upper service temperature of 200 ° C. is only met with thermally very stable diurea chains based on pyromellitic acid esters (B7). Table 3 shows that by adding perfluorinated polyalkyl ether oil an upper service temperature of 220 ° C according to DIN 51825 can only be reached if the mass fraction of perfluorinated polyalkyl ether in oil mixture with lubricating oil based on hydrocarbons is over 40% by weight. Table 1 also shows that the grease compositions according to the invention show better noise behavior than a commercially available grease composition (comparative example B8).

Claims

Grease CompositionsPatent Claims

Grease composition consisting of a mixture of

(a) a hydrocarbon-based oil which consists of an ester of an aromatic di-, tri- or tetracarboxylic acid, with one or in a mixture of C ₇ to C ₂₂ alcohols, a polyphenyl ether or alkylated polyphenyl ether, an ester of Trimethylolopropane, pentaerythritol or dipentaerythritol with aliphatic C ₇ to C ₂₂ carboxylic acids, C _1B dimeric acid esters with C ₇ to C ₂₂ alcohols, complex esters, as individual components or in any mixture,

(b) a perfluorinated polyalkyl ether oil of the general formula

A '- (0-CF ₂ ) _v - (0-C ₂ F ₄ ) _w - (0-C ₃ F ₆ ) _x - (0-C, F „) _y - (0-CF ₂ CF (CF ₃ )) .- OA '' in which A 'is -CF ₃ , -C ₂ F ₅ , -C ₃ F ₇ , -CF ₂ T, where TH or Cl corresponds to,

A '' is the same as A 'or is different -CF ₃ , -C ₂ F ₅ , -C ₃ F ₇ , -CF ₂ T, where TH corresponds to Cl, and v, w, x, y and z are integers ≥ O are

(c) a diurea as a thickener, which is the reaction product of a diisocyanate and an amine of the general formula (H ₂ N) _X R, where R is an alkyl radical with 6 to 22 carbon atoms or an aryl radical with 6 to 123 carbon atoms and x 1 is

(d) usual additives and

(e) organic and inorganic solid lubricants selected from polyimides, PTFE, graphite, metal oxides, boron nitride, molybdenum disulfide and phosphates.

2. Grease composition according to claim 1, characterized gekenn¬ characterized in that the mixing ratio of the oil components of hydrocarbon oil and perfluorinated polyalkyl ether oil is greater than 60/40, which are thickened with 5 to 30 wt .-% diurea and up to 10 wt .-% Additives and / or up to 10 parts by weight of organic or inorganic solid lubricants are added.

3. Grease compositions according to claim 1 or 2, characterized in that the viscosity of the hydrocarbon-based oil is in the range of 10 to 500 mm ² / s and that of the perfluorinated polyalkyl ether oil is 10 to 1500 mm ² / s.

4. Grease compositions according to one of the preceding claims, characterized in that the dropping points according to DIN ISO 2176 are greater than 240 ° C.

5. A process for the preparation of the grease compositions according to one of claims 1 to 4, characterized in that they are obtained either by mixing the hydrocarbon-based oil thickened with diurea with the perfluorinated polyalkyl ether oil and then using a high pressure homogenizer and / or three-roll chair is homogenized or in that the oil based on hydrocarbon is mixed with the perfluorinated polyalkyl ether oil and thickened in this mixture by synthesis of the diurea compound and then homogenized via a high-pressure homogenizer and / or three-roll chair.

6. Grease compositions according to one of claims 1 to 5 for applications for upper service temperatures of more than 180 ° C to 250 ° C according to DIN 51825.