Mineral-Oil-Free Lubricant And Method For Producing A Mineral-Oil-Free Lubricant

Abstract

A method for producing a lubricant in producing an overbased calcium sulfonate, which is converted from the vaterite form into the calcite form and, finally, a calcium sulfonate grease is produced by heating the mixture. A lubricant may comprise at least one ester composition, calcium carbonate and at least one overbased alkylbenzene sulfonate. The basicity of the mixture is limited during the preparation of the overbased calcium sulfonate to a TBN of at most 550 mg KOH/g and during the conversion of the calcium sulfonate to a TBN of at most 450 mg KOH/g. Both the calcium sulfonate and the grease containing said calcium sulfonate may be produced exclusively on an ester basis, so that the end product does not contain any mineral oil and is therefore easily and completely biodegradable.

Claims

1. A method for producing a lubricant which comprises the following steps: a) preparing an overbased calcium sulfonate by performing: dissolving at least one mono-, di- or tri-alkylbenzene sulfonic acid, wherein at least one alkyl group is a (C3-C30)-alkyl group, in at least one ester composition, wherein the ester composition comprises at least one ester; admixing calcium hydroxide and calcium oxide; heating the mixture to a temperature in the range from 30° C. to 90° C. and introducing carbon dioxide into the mixture, wherein the mixture is adjusted to a base number (TBN) of at most 550 mg KOH/g; b) converting the overbased calcium sulfonate from the vaterite form into the calcite form which comprises the following steps: adjusting the mixture to a water content in the range of 2% by wt. to 20% by wt.; heating the mixture to a temperature in the range of 80° C. to 105° C., wherein the mixture is adjusted to a base number of no more than 450 mg KOH/g; and c) producing a calcium sulfonate grease by heating the mixture to a temperature in the range of 90° C. to 200° C.

2. The method according to claim 1, wherein at least one alkyl group of the mono-, di- or tri-alkylbenzene sulfonic acid is a (C10-C18)-alkyl group.

3. The method according to claim 1, wherein the ester composition comprises a synthetic ester and/or a native ester, wherein the ester composition has a viscosity in the range of 2 mm.sup.2/s to 1,200 mm.sup.2/s, preferably 10 mm.sup.2/s to 500 mm.sup.2/s.

4. The method according to claim 1, further comprising adjusting the mixture in step a) to a base number in the range of 150 to 550 mg KOH/g, preferably 210 to 450 mg KOH/g or 320 to 420 mg KOH/g, in particular 211 to 399 mg KOH/g.

5. The method according to claim 1, further comprising adjusting the mixture in step b) to a base number in the range of 50 to 450 mg KOH/g, preferably 70 to 350 mg KOH/g or 100 to 250 mg KOH/g, in particular 80 to 220 mg KOH/g.

6. The method according to claim 1, further comprising heating the mixture in step a) to a temperature in the range of 35° C. to 85° C. or 45° C. to 60° C., in particular 40° C. to 82° C.

7. The method according to claim 1, further comprising heating the mixture in step b) to a temperature in the range of 87° C. to 102° C. or 85° C. to 100° C., in particular 88° C. to 99° C.

8. The method according to claim 1, further comprising heating the mixture in step c) to a temperature in the range of 100° C. to 180° C. or 110° C. to 170° C., in particular 125° C. to 160° C.

9. The method according to claim 1, further comprising adjusting the water content of the mixture in step b) to a content in the range of 5% by wt. to 18% by wt., in particular 7% by wt. to 15% by wt.

10. The method according to claim 1, wherein calcium hydroxide and/or at least one mono-, di- or tri-alkylbenzene sulfonic acid, wherein at least one alkyl group is a (C3-C30) alkyl group, and/or at least one ester composition, and wherein the ester composition comprises at least one ester, is admixed to the mixture in step b).

11. A lubricant produced using a method comprising: preparing an overbased calcium sulfonate by performing: dissolving at least one mono-, di- or tri-alkylbenzene sulfonic acid, wherein at least one alkyl group is a (C3-C30)-alkyl group, in at least one ester composition, wherein the ester composition comprises at least one ester; admixing calcium hydroxide and calcium oxide; heating the mixture to a temperature in the range from 30° C. to 90° C. and introducing carbon dioxide into the mixture, wherein the mixture is adjusted to a base number (TBN) of at most 550 mg KOH/g; b) converting the overbased calcium sulfonate from the vaterite form into the calcite form by performing: adjusting the mixture to a water content in the range of 2% by wt. to 20% by wt.; heating the mixture to a temperature in the range of 80° C. to 105° C., wherein the mixture is adjusted to a base number of no more than 450 mg KOH/g; and c) producing a calcium sulfonate grease by heating the mixture to a temperature in the range of 90° C. to 200° C.

12. A mineral oil-free lubricant comprising: at least one ester composition comprising at least one ester, calcium carbonate and at least one overbased mono-, di- or tri-alkylbenzene sulfonate, wherein at least one alkyl group of the mono-, di- or tri-alkylbenzene sulfonate is a (C3-C30) alkyl group.

13. The lubricant according to claim 12, wherein the lubricant comprises 30% by wt. to 80% by wt. of the ester composition, 5% by wt. to 20% by wt. calcium carbonate and 5% by wt. to 25% by wt. of the overbased mono-, di- or tri-alkylbenzene sulfonate.

14. The lubricant according to claim 12, wherein the lubricant comprises 50% by wt. to 65% by wt. of the ester composition, 10% by wt. to 15% by wt. calcium carbonate and 12% by wt. to 20% by wt. of overbased mono-, di- or tri-alkylbenzene sulfonate.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0036] FIG. 1 shows the creation of overbased calcium sulfonate, wherein calcium carbonate micelles are initially formed from calcium hydroxide, calcium oxide and CO.sub.2, to which alkylbenzene sulfonates with their polar groups are then attached. The non-polar (lipophilic) alkyl residues in this case are directed outwards and therefore surround the CaCO.sub.3 micelles, so that they can be completely dispersed in a base oil (ester composition).

[0037] FIG. 2 shows the structure of overbased calcium sulfonate following the addition of Ca(OH).sub.2.

[0038] FIG. 3 shows the structure of a mixture of overbased calcium sulfonate, Ca(OH).sub.2, benzoic sulfonic acid (di- or mono-alkyl, C10-C18) and acetic acid.

DESCRIPTION OF EXEMPLARY AND PREFERRED EMBODIMENTS OF THE INVENTION

[0039] The following examples represent exemplary embodiments of the method according to the invention, wherein the features described or shown here can represent a subject matter of the invention either individually or in any combination, insofar as nothing which is clearly to the contrary emerges from the context of the above description.

EXAMPLE 1

[0040] 284 g benzene sulfonic acid C10-18-alkyl-derivative are dissolved in 500 g bis (2-ethylhexyl) sebacate (V40: 10 mm2/s). 10 g calcium hydroxide are then added and the mixture is agitated for 30 mins at 50° C. 133 g calcium oxide and 115 g Ca(OH).sub.2 are then added and the mixture is homogenized by further agitation. The temperature is then increased to 60° C. 110 ml water are then added and carbon dioxide is passed through the mixture. The mixture now has a TBN of 367 mg KOH/g. 300 g bis (2-ethylhexyl) sebacate, 200 g benzene sulfonic acid C10-18-alkyl derivative and 120 g water are then added to the formulation. The formulation is heated to 99° C. Following conversion of the calcium carbonate from the vaterite into the calcite form, the formulation is dewatered at 110° C. The TBN is now around 162 mg KOH/g. The formulation is then heated to 160° C. and kept at this temperature for an hour. After cooling, the grease has a consistency (in accordance with ASTM D217) of 331 mm/10 after 60 double strokes. Further technical data can be obtained from Table 2.

EXAMPLE 2

[0041] 280 g benzene sulfonic acid C10-14-alkyl derivative are dissolved in 700 g of a complex ester (fatty acids, C18-unsaturated, dimerized, polymer with 2-ethylhexanol and neopentyl glycol) (V40: 110.5 mm2/s). 11 g calcium hydroxide are then added and agitated for 45 minutes at 50° C. 151 g calcium oxide and 151 g Ca(OH).sub.2 are then added and the mixture is homogenized by agitation. The temperature is then increased to 82° C. 130 g water are then added and carbon dioxide is passed through the mixture. The mixture now has a TBN of 399 mg KOH/g. 300 g complex esters (fatty acids, C18-unsaturated, dimerized, polymer with 2-ethylhexanol and Neopentyl glycol), 220 g benzene sulfonic acid C10-14-alkyl, 21 g acetic acid, 72 g Ca(OH).sub.2 and 180 g water are added to the formulation. The formulation is heated to 92° C. Following conversion of the calcium carbonate from the vaterite form into the calcite form, the formulation is dewatered at 110° C. The TBN is now around 220 mg KOH/g. The formulation is then heated to 160° C. and kept at this temperature for an hour. After cooling, the grease has a consistency (in accordance with ASTM D217) of 292 mm/10 after 60 double strokes. Further technical data can be obtained from the Table 2.

EXAMPLE 3

[0042] 280 g benzene sulfonic acid C10-14-alkyl derivative are dissolved in 500 g neopentyl glycol diisostearate (saturated ester) (V40: 48 mm.sup.2/s). 11 g calcium hydroxide are subsequently added and agitated for 45 minutes at 50° C. 151 g calcium oxide and 131 g Ca(OH).sub.2 are then added and the mixture is homogenized through further agitation. The temperature is subsequently increased to 62° C. 130 ml water are then added and carbon dioxide is passed through the mixture. The mixture now has a TBN of 369 mg KOH/g. 300 g neopentyl glycol diisostearate (saturated ester, 243 g benzene sulfonic acid C10-14-alkyl, 21 g acetic acid, 72 g Ca(OH).sub.2 and 65 g water are then added to the formulation. The formulation is heated to 92° C. Following conversion of the calcium carbonate from the vaterite form into the calcite form, the formulation is dewatered at 110° C. The TBN is now around 188 mg KOH/g. The formulation is subsequently heated to 160° C. and kept at this temperature for an hour. After cooling, the grease has a consistency (in accordance with ASTM D217) of 272 mm/10 after 60 double strokes. Further technical data can be obtained from the Table 2.

EXAMPLE 4

[0043] 260 g benzene sulfonic acid C10-18-alkyl are dissolved in 1000 g complex ester (pentaerythritol sebacic acid isostearic acid copolymer) (V40: 1200 mm.sup.2/s). 9 g calcium hydroxide are then added and agitated for 30 min at 50° C. 101 g calcium oxide and 104 g Ca(OH).sub.2 are then added and the mixture is homogenized through further agitation. The temperature is subsequently increased to 60° C. 130 ml water are then added and carbon dioxide is passed through the mixture. The mixture has a TBN of 335 mg KOH/g. 400 g bis (2-ethylhexyl) sebacate (V40: 12.5 mm2/s), 270 g benzene sulfonic acid C10-14-alkyl, 75 g Ca(OH).sub.2 and 195 g water are then added to the formulation. The formulation is heated to 92° C. Following conversion of the calcium carbonate from the vaterite form into the calcite form, 150 g 12-hydroxystearic acid are added and the formulation is dewatered at 110° C. The TBN is then around 159 mg KOH/g. The formulation is subsequently heated to 160° C. and kept at this temperature for an hour. After cooling, the grease has a consistence (in accordance with ASTM D217) of 261 mm/10 after 60 double strokes. Further technical data can be obtained from FIG. 2.

EXAMPLE 5

[0044] 300 g benzene sulfonic acid C10-18-alkyl are dissolved in 550 g trimethylolpropane trioleate (V40: 46 mm.sup.2/s). 120 g calcium oxide and 100 g Ca(OH).sub.2 are then added and the mixture is homogenized through further agitation. The temperature is subsequently increased to 60° C. 80 ml water are then added and carbon dioxide is passed through the mixture. The mixture now has a TBN of 297 mg KOH/g. 280 g trimethylolpropane trioleate, 280 g benzene sulfonic acid C10-14-alkyl, 72 g Ca(OH).sub.2 and 75 g water are subsequently added to the formulation. The formulation is heated to 92° C. Following conversion of the calcium carbonate from the vaterite form into the calcite form, the formulation is dewatered at 110° C. The TBN is around 180 mg KOH/g. The formulation is subsequently heated to 150° C. and is kept at this temperature for half an hour. After cooling, the grease has a consistency (in accordance with ASTM D217) of 299 mm/10 after 60 double strokes. Further technical data can be obtained from Table 2.

EXAMPLE 6

[0045] 310 g benzene sulfonic acid C8-C22-alkyl are dissolved in 550 g trimethylolpropane trioleate (V40: 46 mm.sup.2/s). 120 g calcium oxide and 100 g Ca(OH).sub.2 are then added and the mixture is homogenized through further agitation. The temperature is subsequently increased to 60° C. 80 ml water are then added and carbon dioxide is passed through the mixture. The mixture now has a TBN of 297 mg KOH/g. 280 g trimethylolpropane trioleate, 254 g benzene sulfonic acid C8-C22-alkyl, 75 g Ca(OH).sub.2, 25 g acetic acid and 70 g water are subsequently added to the formulation. The formulation is heated to 92° C. Following conversion of the calcium carbonate from the vaterite form into the calcite form, the formulation is dewatered at 110° C. and 100 g caproic acid are added. The TBN is now around 161 mg KOH/g. The formulation is subsequently heated to 150° C. and kept at this temperature for half an hour. After cooling, the grease has a consistency (in accordance with ASTM D217) of 287 mm/10 after 60 double strokes. Further technical data are obtained from the Table 2.

EXAMPLE 7

[0046] 322 g benzene sulfonic acid C10-18-alkyl are dissolved in 600 g rapeseed oil (V40: 35 mm.sup.2/s). 140 g calcium oxide and 80 g Ca(OH).sub.2 are then added and the mixture is homogenized by further agitation. The temperature is subsequently increased to 40° C. 62 ml water are then added and carbon dioxide is passed through the mixture. The mixture now has a TBN of 211 mg KOH/g. 240 g rapeseed oil (V40: 35 mm2/s), 288 g benzene sulfonic acid C10-14-alkyl, 24 g acetic acid, 70 g Ca(OH).sub.2 and 49 g water are subsequently added to the formulation. The formulation is heated to 88° C. Following conversion of the calcium carbonate from the vaterite form into the calcite form, 167 g 12-hydroxystearic acid are added and the formulation is dewatered at 110° C. The TBN is then around 80 mg KOH/g. The formulation is subsequently heated to 125° C. and kept at this temperature for 15 minutes. After cooling, the grease has a consistency (in accordance with ASTM D217) of 299 mm/10 after 60 double strokes. Further technical data can be obtained from Table 2.

TABLE-US-00002 TABLE 2 Penetration Dropping Resistance to depth point spray water (ASTM D217) (IP 396) (ASTM D 4049) [mm/10] [° C.] [%] Example 1 331 222 97 Example 2 292 299 81 Example 3 272 280 87 Example 4 261 244 52 Example 5 299 224 93 Example 6 287 287 81 Example 7 299 288 78