HIGH TEMPERATURE LUBRICANT FOR THE FOOD INDUSTRY

Abstract

The invention relates to a food-grade high-temperature lubricant, more particularly a high-temperature oil and a high-temperature grease, comprising the following components: a) at least one oil selected from a trimellitic ester or a mixture of different trimellitic esters, alkylaromatics, preferably an aliphatically substituted naphthalene, or estolides; b) a hydrogenated or fully hydrogenated polyisobutylene or a mixture of hydrogenated or fully hydrogenated polyisobutylene; and c) additives individually or in combination.

In the case of the high-temperature grease, a thickener is added.

Claims

1. A food-grade high-temperature oil comprising the following components: a) 93.9 to 45 wt % of at least one oil selected from the group consisting of a mixture of trimellitic acid tri(iso-C.sub.10) esters (1) and trimellitic acid tri(iso-C.sub.13) esters (2), the mixing ratio of (1) to (2) being 99:1 to 1:99, alkylaromatics, estolides; b) 6 to 45 wt % of a polymer, selected from the group consisting of a hydrogenated or fully hydrogenated polyisobutylene or a mixture of hydrogenated or fully hydrogenated polyisobutylene; c) 0.1 to 5 wt % of additives, individually or in combination, selected from the group consisting of anticorrosion additives, antioxidants, antiwear additives, UV stabilizers, inorganic or organic solid lubricants.

2. A food-grade high-temperature grease comprising the following components: a) 91.9 to 30 wt % of at least one oil selected from the group consisting of a mixture of trimellitic acid tri(iso-C.sub.10) esters (1) and trimellitic acid tri(iso-C.sub.13) esters (2), the mixing ratio of (1) to (2) being 99:1 to 1:99, alkylaromatics, estolides; b) 6 to 45 wt % of a polymer, selected from the group consisting of a hydrogenated or fully hydrogenated polyisobutylene or a mixture of hydrogenated or fully hydrogenated polyisobutylene; c) 0.1 to 5 wt % of additives, individually or in combination, selected from the group consisting of anticorrosion additives, antioxidants, antiwear additives, UV stabilizers, inorganic or organic solid lubricants, and d) 2 to 20 wt % of thickener.

3. The high-temperature oil or grease as claimed in claim 1, wherein the alkylaromatic compound is an aliphatically substituted naphthalene.

4. The high-temperature oil or grease as claimed in claim 1, wherein component a) comprises as a further food-grade oil a compound selected from the group consisting of mineral oil, aliphatic carboxylic and dicarboxylic esters, fatty acid triglycerides, and poly-alpha-olefins.

5. The high-temperature grease as claimed in claim 2, wherein component d) is selected from the group consisting of urea, Al complex soaps, simple metal soaps of the elements of the first and second main groups of the Periodic Table, metal complex soaps of the elements of the first and second main groups of the Periodic Table, bentonites, sulfonates, silicates, Aerosil, polyimides, PTFE or a mixture of the aforesaid thickeners.

6. The use of the high-temperature oil and/or high-temperature grease as claimed in claim 1 for the lubrication of equipment in food processing, as a hydraulic oil in the food industry, for transport chains and control chains, for devices for the processing of cereal, flour, and animal feed, and also in baking ovens.

7. The use of the high-temperature oil as claimed in claim 1 as oil in the form of a spray.

8. The high-temperature oil or grease as claimed in claim 2, wherein the alkylaromatic compound is an aliphatically substituted naphthalene.

9. The high-temperature oil or grease as claimed in claim 2, wherein component a) comprises as a further food-grade oil a compound selected from the group consisting of mineral oil, aliphatic carboxylic and dicarboxylic esters, fatty acid triglycerides, and poly-alpha-olefins.

10. The use of the high-temperature oil and/or high-temperature grease as claimed in claim 2 for the lubrication of equipment in food processing, as a hydraulic oil in the food industry, for transport chains and control chains, for devices for the processing of cereal, flour, and animal feed, and also in baking ovens.

Description

EXAMPLES 1 TO 7

Production of a High-Temperature Oil of the Invention for the Food Industry

[0048] Two trimellitic esters are charged to a stirred vessel. At 100° C., with stirring, the polyisobutylene and optionally a further oil are added. The mixture is subsequently stirred for 1 hour in order to give a homogeneous mixture. The antiwear agents and the antioxidant are added to the vessel with stirring at 60° C. After about 1 hour, the completed oil can be dispensed into the intended containers.

Composition of the High-Temperature Oils

[0049] Table 1 shows the compositions of the high-temperature oils and the redissolubility of the oil residue after complete evaporation of the oil, as a function of the amount of polyisobutylene added.

TABLE-US-00001 TABLE 1 Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 Fully 24.41 22.0 19.53 17.1 14.63 12.2 9.76 hydrogenated polyisobutylene C.sub.10 branched 71.52 73.91 76.35 78.76 81.2 83.61 86.02 Trimellitic ester (1) C.sub.13 branched 0.72 0.74 0.77 0.79 0.82 0.84 0.87 trimellitic ester (2) Viscosity 40° C. 426.8 375.5 328.7 292.7 259 228.8 202.8 mm.sup.2/s Dissolubility of 4 3 3 2 1 1 1 residue after 72 h/250° C. (varnish) (varnish) (varnish) 4 = residue very dissoluble after full evaporation 3 = residue readily dissoluble after full evaporation 2 = residue partially dissoluble after full evaporation 1 = residue not dissoluble after full evaporation

[0050] All figures are in % by weight. The balance to 100 wt % is made up by the addition of additive, especially aminic and/or phenolic antioxidants, anticorrosion additives, antiwear additives EP/AW, metal deactivators.

[0051] These results show that up to a kinematic viscosity at 40° C. of 292.7 mm.sup.2/s, it is possible for residues formed after full evaporation to be redissolved using fresh oil. The composition according to example 1 shows the best properties in terms of viscosity and redissolubility.

[0052] In comparison to comparative examples 1 to 3, examples to 10 below show the outstanding properties of the food-grade high-temperature oil of the invention in relation to dissolubility when different components a) are used as oil.

EXAMPLES 8 TO 10

[0053] Composition of the oils (all figures are in wt %)

TABLE-US-00002 TABLE 2 Inventive Comparative example 8 example 1 Trimellitate 1 70.0 52.65 Trimellitate 2 0.7 44.0 Hydrogenated PIB 25.95 0.0 Aminic antioxidant 0.5 0.5 Phenolic antioxidant 1.5 1.5 Antiwear additive EP/WA 1.0 1.0 Anticorrosive agent 0.25 0.25 Metal deactivator 0.1 0.1 Dissolubility very good (4) poor (1)

TABLE-US-00003 TABLE 3 Inventive Comparative example 9 example 2 Trimellitate 1 0.0 52.65 Trimellitate 2 0.0 44.0 Alkylated naphthalene 70.65 0.0 Hydrogenated PIB 26.0 0.0 Aminic antioxidant 0.5 0.5 Phenolic antioxidant 1.5 1.5 Antiwear additive EP/WA 1.0 1.0 Corrosive agent 0.25 0.25 Metal deactivator 0.1 0.1 Dissolubility very good (4) poor (1)

TABLE-US-00004 TABLE 4 Inventive Comparative example 10 example 3 Trimellitate 1 0.0 52.65 Trimellitate 2 0.0 44.0 Estolide 1 40.4 0.0 Estolide 2 23.25 0.0 Hydrogenated PIB 33.00 0.0 Aminic antioxidant 0.5 0.5 Phenolic antioxidant 1.5 1.5 Antiwear additive EP/WA 1.0 1.0 Corrosive agent 0.25 0.25 Metal deactivator 0.1 0.1 Dissolubility very good (4) poor (1)

[0054] Table 5 provides an exemplary description below of the food-grade high-temperature greases of the invention.

TABLE-US-00005 TABLE 5 Ex. Ex. Ex. Ex. Ex. Ex. Ex. 11 12 13 14 15 16 17 Trimellitate 1 46.3 0.0 46.3 39.0 46.3 46.3 46.3 Trimellitate 2 17.1 0.0 17.1 20.0 17.7 17.7 18.7 Estolide 1 0.0 38.4 0.0 0.0 0.0 0.0 0.0 Estolide 2 0.0 25.6 0.0 0.0 0.0 0.0 0.0 Alkylated 0.0 0.0 0.0 0.0 0.0 0.0 0.0 naphthalene Fully 25.0 25.0 25.0 25.0 25.0 25.0 25.0 hydrogenated PIB Antioxidant 1.0 1.0 1.0 1.0 1.0 1.0 1.0 Thickener 10.6 10.0 10.6 15.0 10.0 10.0 9.0

[0055] To determine the redissolubility, the samples were conditioned at 250° C. for 72 hours. The residue was redissolved using the respective base oil of the grease specimen. In all examples the redissolubility was good.

[0056] The thickeners used in examples 11 to 16 are complex Li (Ex. 11 and 12), complex Al (Ex. 13), bentonite (Ex. 14), simple Ca (Ex. 15), simple Li (Ex. 16), and urea (Ex. 17).

[0057] Furthermore, the redissolubility of the oil residue after full evaporation at two different temperatures (220° C./120 h) and (250° C./72 h) was investigated as a function of the mixing ratio of the two trimellitic esters (1) and (2). The concentration of the fully hydrogenated PIB was kept constant at 25 wt %. It was found, surprisingly, that for both temperatures the redissolubility is dependent on the mixing ratio of the two trimellitic esters. At a mixing ratio of 0.02, i.e., with a high fraction of the iso-C.sub.13 trimellitic ester over the iso-C.sub.10 ester, the residue is not redissoluble with fresh oil, but the dissolubility increases significantly as the amount of iso-C.sub.10 trimellitic ester goes up, as is evident from FIG. 1. A saturation point is reached at a mixing ratio of 1:1. The values are also shown in table 6.

TABLE-US-00006 TABLE 6 Dissolubility of residue after full Ratio evaporation (aging) iso-C10/iso-C13 250° C./72 h 220° C./120 h 0.02 1 1 0.33 2 3 1.00 3 4 2.97 3 4 87.12 3 4 4 = residue very dissoluble after full evaporation 3 = residue readily dissoluble after full evaporation 2 = residue partially dissoluble after full evaporation 1 = residue not dissoluble after full evaporation

[0058] It was possible to show, accordingly, that the dissolubility of the residues is dependent not only on the degree of hydrogenation of the polyisobutylene but also on the mixing ratio of the two esters. Both esters must be used in combination in order to ensure the H1 capacity of the high-temperature oil. The mixing ratios are freely selectable, with the preferred ranges beginning from a 1:1 mixture. The particularly preferred ratio is 87.12 (iso-C.sub.10/iso-C.sub.13).

[0059] The above-described food-grade high-temperature oils and high-temperature greases can also be used for lubricating equipment subject to limitations similar to those relating to the requirements imposed on the lubricants. Included here are the cosmetic and pharmaceutical industries and also the animal feed industry.

[0060] With regard to the food industry, the high-temperature lubricants of the invention can be used for the lubrication of equipment in food processing, as hydraulic oils for the food industry, for transport chains and control chains in the food industry, and also for devices for the processing of cereal, flour, and animal feed, and also for baking ovens.

[0061] For certain applications, use in the form of a spray is advantageous.