Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Organic compound containing boron
Reexamination Certificate
2001-03-12
2003-01-28
McAvoy, Ellen M. (Department: 1764)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Organic compound containing boron
C508S196000, C508S514000, C508S517000, C508S552000, C072S042000
Reexamination Certificate
active
06511946
ABSTRACT:
Subject matter of the invention is a water-miscible cooling lubricant concentrate which mixed with water is distinguished by excellent functional properties in metal cutting and non-cutting metal working as well as also through its especially high cutaneous tolerance.
According to information by the Arbeitsgemeinschaft der Metallberufsgenossenschaften cooling lubricants are involved in nearly 40% of the causes of occupational skin diseases in the industrial field (Brochure ZH 1/467, Hautschutz in Metallbetrieben, Arbeitsgemeinschaft der Metallberufsgenossenschaften, 1996).
Cooling lubricants are employed in metal cutting and in metal forming for the cooling and lubricating of workpieces. They are applied in the case of cutting working processes such as milling, turning, drilling and grinding as well as also in the case of non-cutting forming such as rolling, deep-drawing or cold impact forming. According to DIN 51385 one differentiates between water-miscible and water-mixed cooling lubricants. By the term “water-mixed” is understood the final state of the ready medium, most frequently in the form of an oil-in-water emulsion, and by “water-miscible” is understood the concentrate of the cooling lubricant.
Water-mixed cooling lubricants are produced by the user by mixing the concentrate with water. As an emulsion, solution or also in concentrated form its main purpose in metal working is the cooling, the lubrication and the dispersal away from the workpiece and tool of removed material generated by the multiplicity of production operations such as turning, drilling, milling, grinding etc. In addition, the water-mixed cooling lubricant meets a multiplicity of further secondary tasks, such as keeping free of debris the systems and lending [anti]corrosion protection to the machine parts.
Depending on the application concentration and the type of cooling lubricant, conventionally used water-mixed cooling lubricants have a pH value between 8.2 and 9.4, which only in exceptional cases can be still higher. Of disadvantage is that a high pH value lowers the cutaneous tolerance of the cooling lubricant since the protective acidic envelope of the skin is thereby destroyed and with relatively long exposure times the operator of the metal processing machine may develop skin problems. Lowering the pH value of water-mixed cooling lubricants to the point of neutrality has so far been found to be impossible since in that case the high requirements made of the rust inhibition effect of water-mixed cooling lubricants can no longer be met. After the working in cooling lubricants, it is generally not customary for reasons of economy, or due to the linking of fabrication processes, to dry the worked metal part or to provide it with a special corrosion protection. The parts are normally placed into boxes while wet and must thus also not rust in the wet state. For testing the effect of the rust protection during development and also while checking the water-mixed cooling lubricants, in general the test is performed using cast-iron turnings according to DIN 51360-1 and -2. This test demonstrates that the danger of rust formation on the worked metal part is greater the further the pH value of the water-mixed cooling lubricant shifts away from the alkaline in the direction toward the neutral pH range.
The task was therefore posed of providing a water-mixed cooling lubricant whose pH value is as close as feasible to the neutral point and nevertheless does not lead to the formation of rust on metal parts which had been worked with an aqueous solution of the cooling lubricant.
This task is solved through a water-miscible cooling lubricant concentrate which comprises natural or synthetic mineral oils, emulsifying agents, corrosion protection additives, solubilizers, means of preservation, metal inhibitors and other conventional additives and which, after dilution to form a 2 to 25% by weight aqueous solution, has a pH value between 7.0 and 7.5 as well as, additionally, as means of preservation and/or corrosion protection additive comprises a mixture of
a) a conversion product of boric acid and a primary or tertiary alkanolamine and/or
b) an ethoxylated and/or propoxylated fatty acid or a fatty acid alkanolamide as well as at least one further compound selected from the group comprised of
c) a carboxylic acid imide, a phosphoric acid ester, a triazole, a thiadiazole, an isothiazolinone, an imidazole, a guanidine, an aromatic carboxylic acid and the 3-iodo-2-propinyl-carbamate and/or
d) a methylol urea derivative.
Such a cooling lubricant concentrate comprises as the natural or synthetic mineral oils paraffinic or naphthenic hydrocarbons, which can also be mixed in quantitative proportions of 1:3 to 5:1, white oils, esters, polyisobutenes, polyvinylpyrrolidones or polyalkylene glycols. These compounds, also referred to as base oils, are generally comprised in proportions of 5 to 80% by weight, preferably in proportions of 5 to 50% by weight in the cooling lubricant concentrate.
Among the additives which must be worked into the base oil, the emulsifying agents represent the most important group in the production of the cooling lubricant concentrate according to the invention. Especially anionic emulsifying agents such as alkali salts of saturated or unsaturated carboxylic acids, alkali salts of sulfonates and sulfonic acids as well as salts of phosphoric acid esters have a highly specific significance. But, in addition, also used with success are non-ionic emulsifying agents, especially fatty alcohol ethoxylates, fatty, alcohol propoxylates, sugar esters, neopentyl glycol esters, pentaerythritol esters, 2-ethyl hexyl esters and trimethylolpropane esters for the production of the water-miscible cooling lubricant concentrate.
Of particular significance is the selection of suitable corrosion protection means. Neutral conversion products of boric acid with primary or tertiary alkanolamines as well as ethoxylated or propoxylated acids or fatty acid alkanolamides have been found to be particularly useful. By using boric acid compounds, moreover, the cooling lubricant biostasis and the buffering capacity can be increased. In practice, higher service life of the cooling lubricant is attained and consequently its economy it improved. The markedly increased biocidal activity of boric acid compounds, which is primarily observed in the low pH range and which can be explained by the enzymes of the phosphate metabolism of the microorganisms being blocked, permits, in addition, reducing the inhibitors against the growth of microorganisms to be added. Surprisingly, the corrosion protection of boron compounds is considerably increased if they are used together with polyalkoxylated fatty acid amides and/or imides, especially with neutral ethoxylated and/or propoxylated fatty acid amides based on plant and/or animal origin and/or specifically adjusted fatty acid mixtures and/or alkyl succinimides or with other corrosion protection additives, comprised also in conventional cooling lubricant formulations, for example phosphoric acid esters, triazoles or thiadiazoles, wherein the corrosion protection means is to be added in proportions of 5 to 25% by weight. A water-mixed cooling lubricant provided with said corrosion protection additives, even at a pH value between 7.0 and 7.5 in aqueous solution, shows a corrosion protection which is equivalent according to DIN 51360-1 and -2 to the cooling lubricants used up to now. If formulations free of boric acid are employed, which comprise ethoxylated and/or propoxylated fatty acid alkanolamides, a concentration of 2 to 25% by weight suffices to attain a corrosion protection which meets the most stringent demands made up to now of cooling lubricants. If, as the corrosion protection means fatty acids, in particular ether carboxylic acids, are used, an ethoxylation degree of 2 to 12 mole ethylene oxide per mole of ether carboxylic acid is especially advantageous. Such ethoxylated ether carboxylic acids are employed as anticorrosion means in concentrations of 2 to 15% by weight.
It h
Schwab Rüdiger
Theis Heinz Gerhard
Fuchs Petrolub AG
McAvoy Ellen M.
Wenderoth , Lind & Ponack, L.L.P.
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