Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Heterocyclic ring compound; a heterocyclic ring is one...
Reexamination Certificate
2000-01-19
2001-07-24
Johnson, Jerry D. (Department: 1721)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Heterocyclic ring compound; a heterocyclic ring is one...
C508S232000, C508S240000, C508S464000, C508S552000
Reexamination Certificate
active
06265359
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to imide-diurea and imide-urethane urea grease thickeners made in situ as a one pot preparation involving a sequential reaction but without making use of any organic solvents.
2. Description of the Related Art
Grease is a semi-fluid medium comprised of a liquid lubricant and a thickener. The liquid lubricant is derived from natural mineral oils, synthetic hydrocarbons, esters, ethers, polysiloxanes, fluorocarbon polymers etc. A wide variety of compounds are used as thickeners. For example mineral oils are thickened by alkali or alkaline earth metal soaps of fatty acids, clays, polymers, phthalocyanines, organic dyes, polyureas and others. The most commonly used thickners are those containing lithium, calcium, or sodium salts of natural fatty acids. At present, lithium soaps of stearic acid and 12-hydroxy stearic acid is commonly used. Imide-urea thickeners have also been used, as disclosed in JP 79 114 506, in which acetone, a volatile organic solvent is used to dissolve the starting materials. U.S. Pat. No. 5,585,335 describes the use of a metal salt based on imide-carboxylic acid in combination with a bi-metal phthalate complexing agent. JP 57 109 896 discloses lubricating greases manufactured by compounds containing 4 to 8 imide groups per molecule, in which the starting materials are dissolved in N,N-dimethyl formamide, a non-volatile, high-boiling organic solvent. JP 56 139 592 discloses lubricating oils thickened by two imide and two amide groups per molecule in which acetone is used as a carrier for the anhydride and the amine. Another Japanese patent publication JP 54 113 605 discloses a lubricating grease thickened with an imide compound, in which acetone is used to dissolve the anhydride and amino compounds.
An object of this invention is to propose a process for the preparation of imide-diurea and imide-urethane urea grease thickeners.
Another object of this invention is to propose a process for the preparation of imide-diurea and imide-urethane urea grease thickeners which avoids the use of volatile or non-volatile, low-boiling or high-boiling organic solvent.
Still another object of this invention is to propose a process for the preparation of imide-diurea and imide-urethane urea grease thickeners which avoids the difference in reactivity of the reactants employed and to maximize the formation of products capable of thickening the oil of lubricating quality.
A further object of this invention is to propose a process for the preparation of imide-diurea and imide-urethane urea grease thickeners which exhibits excellent storage stability without showing any age hardening tendency.
A still further object of this invention is to propose a grease and a grease thickening system.
SUMMARY OF THE INVENTION
According to this invention there is provided a process for the preparation of imide-diurea and imide-urethane urea grease thickeners comprising in reacting a dibasic acid selected from the group consisting of succinic acid, maleic acid, glutaric acid, and phthalic acid and anhydrides thereof, with a reactant selected from a primary diamine and a primary amino hydroxy compound having 2 to 10 carbon atoms followed by the reaction with toluene diisocyanate and, thereafter, with a primary monoamine having 8 to 22 carbon atoms.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The use of a solvent-free process as employed in this invention has several advantages. The solvent, if it were volatile or low-boiling will not be let-off into the atmosphere. If the solvent were non-volatile or high-boiling it should be removed from the grease for which purpose the grease kettle is modified with provisions such as vacuum, since the presence of solvent will alter the consistency of the grease.
The sequential addition of reactants as followed in this invention provides a smooth grease of required consistency. Since the reactivity of isocyanate group is far greater than that of an anhydride moiety, in the presence of both of these functional groups, another reactive functional group would preferentially react with the former than the latter. Thus, when an aminohydroxy compound and a primary amine are present in a mixture consisting of an isocyanate and an anhydride, it would result in urea and urea-ester rather than urethane. The thickening efficiency of urea-ester would be questionable. Thus, the sequential addition of reactants accommodates the reactivity differences and hence minimizes the number of products formed, thereby resulting in products capable of thickening the oil.
The fatty monoamine employed in this invention helps to formulate a grease of excellent storage stability and also to prevent age-hardening.
The invention relates to imide-diurea and imide-urethane urea grease thickeners. By imide-diurea or imide-urethane urea is meant a grease thickening compound having imide-urea and imide-urethane urea chemical functionality useful for forming a grease when added in an effective amount to a liquid lubricant such as a hydrocarbon oil and particularly to a hydrocarbon oil of lubricating quality.
Imide-diurea and imide-urethane urea useful as thickeners in the practice of this invention include one or more organic compounds which comprise a reaction product of diacid or anhydride, diamine or amino-hydroxy compound, toluene diisocyanate and a monoamine. These ingredients when added in a sequence to a hydrocarbon oil having lubricating quality, at high temperature, result in a grease exhibiting high dropping point, good mechanical sheal stability, superior water resistance, excellent corrosion and rust inhibiting characteristics, better oxidation stability and prolonged service life in high temperature life performance test.
The thickener of this invention comprises an imide-diurea or imide-urethane-urea compound which is the product of a sequence of reactions involving a diabasic acid selected from succinic acid, maleic acid, glutaric acid and phthalic acid and anhydrides thereof, a primary diamine having a straight or branched, cylic or acyclic saturated or unsaturated hydrocarbon radical with 2 to 10 carbon atoms, or saturated/unsaturated primary amino hydroxy compound of 2 to 10 carbon atoms, toluene diisocyanate which is selected from at least one of the groups consisting of 2,4-toluene diisocyanate and 2,6-toluene diisocyanate, 2,4-toluene diisocyanate containing a minor amount of 2,6-toluene diisocyanate is commercially available, and a primary monoamine consisting of 8 to 22 carbon atoms which may be saturated or unsaturated, cyclic or acyclic.
The reaction between the dibasic acid or anhydride and the primary amine is carried out while the mole ratio of the dibasic acid or anhydride to the primary diamine is adjusted to 0.9 to 1:1. The reaction conditions are atmospheric pressure and a temperature of 80° to 220° C. The proportion of dibasic acid or anhydride to that of primary diamine, is adjusted according to the nature of the diamine. If the diamine employed is a liquid of low boiling point then the amount of dibasic acid or anhydride is reduced by 5 to 10 weight % in order to prevent the sublimation of dibasic acid or anhydride.
The reaction products obtained by heating 0.9 to 1 mole of the aforementioned succinic acid, maleic acid, glutaric acid, phthalic acid or the anhydrides thereof and one mole of straight or branched, cyclic or acyclic saturated or unsaturated primary diamine with 2 to 10 carbon atoms, or one mole of saturated or unsaturated, straight or branched, cyclic or acyclic primary amino hydroxy compound of 2 to 10 carbon atoms are imide compounds with one free primary amino or hydroxyl group. The imide compounds are obtained as solids dispersed in the oil. As stated above, the reaction is carried out at atm. pressure at a temperature of 80° to 220° C. After this step, the reaction mixture is cooled down to 100° C. to 180° C., preferably to 100° C. to 160° C., most preferably to 110° to 150° C. and one mole of toluene diisocyanate which is a mixture of 2,4- and 2,6-isomers is added follow
Bhatnagar Akhilesh Kumar
Naithani Kanta Prasad
Parthiban Anbanandam
Johnson Jerry D.
Spencer George H.
Venable
Wells Ashley J.
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