Abstract:
The oxidation of a lubricating oil caused by metal components can be suppressed effectively by adding to the lubricating oil a compound represented by the formula ##STR1##

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to a metal deactivator and a composition containing the same. More particularly, it is concerned with a metal deactivator having a new chemical structure suitable as an additive to lubricating oils or the like and also with a composition containing the same. 
     The metal deactivator is an additive for deactivating dissolved metal salts which promote the oxidation of fuels and lubricating oils or for forming an inert film on the metal surface. As the metal deactivator there are widely known benzotriazole, its derivatives, and thiadiazole. But these compounds have not always been satisfactory in their performance. 
     SUMMARY OF THE INVENTION 
     It is an object of this invention to provide a new metal deactivator having a superior performance to that of conventional metal deactivator. 
     It is another object of this invention to provide a composition containing a new metal deactivator. 
     Other objects and advantages of this invention will become apparent from the following description. 
     The aforesaid objects of this invention can be attained by a metal deactivator comprising at least one member selected from the group consisting of compounds represented by the formula I ##STR2## compounds represented by the formula II ##STR3## compounds represented by the formula III ##STR4## and compounds represented by the formula IV ##STR5## and also by a composition comprising at least one member selected from the group consisting of mineral and synthetic oils having a kinematic viscosity of 10 to 10,000 cSt (40° C.) and a viscosity index of not less than 80, and 0.001% to 10.0% by weight, based on the total weight of the composition, of the above metal deactivator. In the above formulae I, II, III and IV, R 1 , R 2 , R 3 , R 4 , R 5  and R 6 , which may be alike or different, are each a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, a cycloalkyl group having 5 to 12 carbon atoms, an aryl group having 6 to 10 carbon atoms, an aralkyl group having 7 to 9 carbon atoms, or a group represented by the formula R 7  O(R 8  O) n  R 9  wherein R 7  is a hydrogen or an alkyl group having 1 to 20 carbon atoms, R 8  and R 9  are each independently an alkylene group having 2 or 3 carbon atoms and n is an integer of 0 to 4. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A more detailed description will be given hereinunder about a metal deactivator and a composition containing the same both according to this invention. 
     The compounds represented by the formulae I and II are tetrazol derivatives, in which formulae R 1 , R 2  and R 3  may be alike or different; that is, in the case of using a compound of the formula I, R 1  and R 2  may be alike or different, and in the case of using a mixture of a compound of the formula I and a compound of the formula II, R 1 , R 2  and R 3  may be alike or different. 
     The compounds represented by the formulae III and IV are hydroxyquinoline derivatives, in which formulae R 4 , R 5  and R 6  may be alike or different; that is, in the case of using a compound of the formula III, R 4  and R 5  may be alike or different, and in the case of using a mixture of a compound of the formula III and a compound of the formula IV, R 4 , R 5  and R 6  may be alike or different. Of course, there may be used a mixture of two or more compounds represented by the same formula, and also there may be employed a mixture of a compound(s) represented by the formula I and/or the formula II and a compound(s) represented by the formula III and/or IV. 
     In case any one or more of R 1  through R 6  are each an alkyl group, there may be used alkyl groups having 1 to 20 carbon atoms, but particularly preferred are those having 3 to 18 carbon atoms. Preferred examples are butyl, hexyl, octyl, 2-ethyl-hexyl, decyl, dodecyl, hexedecyl and octadecyl. 
     In case any one or more of R 1  through R 6  are each an alkenyl group, there may be used alkenyl groups having 2 to 20 carbon atoms, but particularly preferred are those having 3 to 18 carbon atoms. Preferred examples are butenyl, octenyl, decenyl, dodecenyl, tetradecenyl and octadecenyl (oleyl). 
     In case any one or more of R 1  through R 6  are each a cycloalkyl group, there may be used cycloalkyl groups having 5 to 12 carbon groups with cyclohexyl being a preferred example. 
     In case any one or more of R 1  through R 6  are each an aryl group, there may be used aryl groups having 6 to 10 carbon atoms with phenyl and naphthyl being preferred examples. 
     In case any one or more of R 1  through R 6  are each an aralkyl group, there may be used aralkyl groups having 7 to 9 carbon atoms with benzyl being a preferred example. 
     In case any one or more of R 1  through R 6  are each a group represented by the formula R 7  O(R 8  O) n  R 9 , R 7  is a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 to 8 carbon atoms and still more preferably a hydrogen atom, R 8  and R 9  are each an alkylene group having 2 to 3 carbon atoms, and n is an integer of 0 to 4 and more preferably 0. Preferred examples are hydroxyethyl, methoxyethyl, n-butoxyethyl, methoxyethoxyethyl, n-butoxyethoxyethyl and n-octyloxypropyloxy. 
     There is no special limit to the manufacturing method for the tetrazole derivatives or hydroxyquinoline derivatives in this invention. For example, however, in order to obtain a compound of the formula I, the Mannich reaction of tetrazole, a secondary amine which satisfies the foregoing conditions of R 1  and R 2  and formaldehyde is preferred, and in order to obtain a compound of the formula II, the Mannich reaction of tetrazole, a primary amine which satisfies the foregoing conditions of R 3  and formaldehyde is preferred. Furthermore, in order to obtain a compound of the formula III, the Mannich reaction of 8-hydroxyquinoline, a secondary amine which satisfies the foregoing conditions of R 4  and R 5  and formaldehyde is preferred, and in order to obtain a compound of the formula IV, the Mannich reaction of 8-hydroxyquinoline, a primary amine which satisfies the foregoing condition of R 6  and formaldehyde is preferred. 
     Among the metal deactivating compounds according to this invention, the compounds represented by the formula I and III are more preferable, and particularly preferred are those wherein R 1 , R 2 , R 4  and R 5  are alike or different and are alkyl groups having 3 to 18 carbon atoms, especially hexyl, octyl, decyl, dodecyl, hexadecyl and octadecyl. 
     The composition of this invention contains 0.001% to 10.0% by weight, preferably 0.01% to 1.0% by weight, of at least one of the foregoing metal deactivating compounds, and the whole or main part of the balance is a mineral oil and/or a synthetic oil having a kinematic viscosity of 10 to 10,000 cSt (40° C.), preferably 90 to 200. As the mineral oil there is preferably used a lubricating oil fraction of petroleum after refining by hydrotreating, clay treating, solvent refining or a combination thereof. Preferred examples of the synthetic oil are polybutenes, poly-α-olefins, diesters, polyol esters, and mixtures thereof. If the amount of the metal deactivator is smaller than 0.001% by weight, it will be impossible for the same agent to display the expected effect, while a larger amount thereof than 10.0% by weight is not desirable from the economic point of view. 
     In the composition of this invention there may be incorporated, if required in addition to the aforesaid metal deactivator, an anti-oxidant, a detergent-dispersant, a viscosity index improver, a pour-point depressant, a rust preventive agent, an extreme-pressure agent, an oiliness improver, or an antifoaming agent. The details of these additives is disclosed, for example, in the &#34;Lubrication Society Proceedings Vol. 15 No. 6&#34; or Toshio Sakurai, &#34;Petroleum Product Additives&#34; (Saiwai Shobo). 
     The metal deactivator and the composition containing same of this invention are preferably used as additives to lubricating oils, for example, turbine oil, hydraulic oil, gear oil, gasoline-engine oil, diesel-engine oil, marine-engine oil, compressor oil, oil-film bearing oil, refrigerator oil, slide-way lubricating oil, rolling oil, machine tool oil, automatic transmission oil, various metalworking oils and greases, and also to electrical insulating oil, heat transfer oil and rust preventive oil. 
     The following are preparation examples, working examples and comparative examples for further illustration of this invention. 
     PREPARATION EXAMPLE 1 
     150 ml. of methanol was added to 7.0 g. of tetrazole and 24.1 g. of bis(2-ethylhexyl)amine and stirring was made in a nitrogen gas stream, to which was dropwise added 10.4 ml. of a 35% aqueous formalin solution, and reaction was allowed to proceed for 1 hour at 25° C. followed by refluxing for 5 hours in the presence of methanol. Thereafter, the reaction product was filtered and methanol removed, then n-hexane was added and the n-hexane soluble was recovered to yield 265 g. of [bis(2-ethylhexyl)aminomethylene]-1,2,3,4-tetrazole (a compound of the formula I wherein both R 1  and R 2  are 2ethylhexyl). In the same manner, by the Mannich reaction there were prepared tetrazole derivatives 1 through 12 represented by the formula I and tetrazole derivatives 13 through 15 represented by the formula II. 
     
                       TABLE 1______________________________________Preparation of tetrazole derivativesrepresented by the formula I ##STR6##                 AnalysisCompound R.sub.1     R.sub.2    % C  % H  % N______________________________________(I)-1    2-ethylhexyl                2-ethylhexyl                           67.1 11.4 21.5(I)-2    n-butyl     n-butyl    56.7 10.3 33.8(I)-3    n-hexyl     n-hexyl    62.9 10.8 26.2(I)-4    n-octyl     n-octyl    66.9 11.4 21.7(I)-5    cyclohexyl  cyclohexyl 63.4 10.1 26.4(I)-6    n-octadecyl n-octadecyl                           75.6 12.7 11.6(I)-7    nonenyl     nonenyl    69.1 10.6 20.1(I)-8    phenyl      phenyl     66.9  5.2 27.9(I)-9    octylphenyl octylphenyl                           76.1  9.9 13.8 (I)-10  n-octyloxy  n-octyloxy 60.8 10.7 14.8    propyloxy   propyloxy (I)-11  benzyl      benzyl     68.9  6.1 25.0 (I)-12  phenyl      n-octyl    76.7  8.7 14.5______________________________________ 
    
     
                       TABLE 2______________________________________Preparation of tetrazole derivativesrepresented by the formula II ##STR7##           AnalysisCompound   R.sub.3    % C       % H  % N______________________________________(II)-13    nonylphenyl                 58.5      7.8  32.8(II)-14    octadecyl  60.9      9.9  29.1(II)-15    cyclohexyl 45.4      6.8  47.7______________________________________ 
    
     EXAMPLES 1-15 AND COMPARATIVE EXAMPLES 1, 2 
     The tetrazole derivatives 1 through 15 obtained in Preparation Example 1 were added to a mineral oil and their performance as a metal deactivator was evaluated according to the following copper plate corrosion test and oxidation test, the results of which are shown in Table 3. 
     In the copper plate corrosion test, first a sample oil was prepared by adding 1.0 wt.% of olefin sulfide (sulfur concentration 40.8%) to &#34;FBK Turbine Oil 32&#34; (a product of Nippon Oil Co.) (kinematic viscosity 32.5 cSt at 40° C., viscosity index 102), then 0.01 wt.% of the tetrazole derivatives was added to the sample oil, and there was conducted a copper plate corrosion test (at 100° C., 3 hours) according to JIS K 2513 which corresponds to ASTM-D 130. 
     In the oxidation text, 0.1 wt.% of the tetrazole derivatives was added to the &#34;FBK Turbine Oil 32&#34; (a product of Nippon Oil Co.) and there was made a rotary pump oxidation test (at 150° C., oxygen pressure 13 kg/cm 2 , using a copper wire catalyst) according to ASTM D 2272, then the results were evaluated in terms of time required to absorb 1.8 kg/cm 2  of oxygen. 
     
                       TABLE 3______________________________________Test Results              Test Results                Copper Plate                           Oxidation                Corrosion  TestMetal deactivator    Test       (minutes)______________________________________Example 1   Tetrazole derivative (I)-1                    1a         8502       (I)-2            1a         8413       (I)-3            1a         8684       (I)-4            1a         8285       (I)-5            1a         7616       (I)-6            1a         4287       (I)-7            1a         3808       (I)-8            1a         6759       (I)-9            1a         45110      (I)-10           1a         36511      (I)-11           1a         78412      (I)-12           1a         84113      (I)-13           1a         67314      (I)-14           1a         74815      (I)-15           1a         64616      (I)-1 + (II)-13  1a         780   (50 wt % + 50 wt %)Compara-tiveExample 1   None             2a         2342       Benzotriazole    1a         311______________________________________ 
    
     The tetrazole derivatives according to this invention exhibited a superior performance in both copper plate corrosion test and oxidation test, and also in their application as lubricating oils such as turbine oil and hydraulic oil they showed a desirable performance. 
     PREPARATION EXAMPLE 2 
     150 ml. of methanol was added to 16.0 g. of 8-hydroxyquinoline and 24.2 g. of bis(2-ethylhexyl)amine and stirring was made at 20° C., to which was dropwise added 10.4 ml. of a 35% aqueous formalin solution, and reaction was allowed to proceed for 1 hour at 20° C. followed by refluxing for 3 hours at the boiling point of methanol. The reaction product, after adding water and methanol, was extracted with n-hexane, the solvent was removed and subsequent drying yield 22.5 g. of 7-bis(2-ethylhexyl)aminomethylene-8-hydroxyquinoline (a compound of the formula III wherein both R 1  and R 2  are 2-ethylhexyl). In the same manner, by the Mannich reaction there were prepared hydroxyquinoline derivatives 1 through 13 represented by the formula III and hydroxyquinoline derivatives 14 through 17 represented by the formula IV. 
     
                       TABLE 4______________________________________Preparation of hydroxyquinoline derivativesrepresented by the formula III ##STR8##Com-                 Analysispound  R.sub.4    R.sub.5    % C  % H  % N  O______________________________________(III)-1  2-ethylhexyl             2-ethylhexyl                        78.1 10.9 7.0  4.0(III)-2  n-butyl    n-butyl    75.6 9.2  9.6  5.5(III)-3  n-hexyl    n-hexyl    77.3 10.1 8.0  4.6(III)-4  n-octyl    n-octyl    78.0 11.0 7.0  4.0(III)-5  n-dodecyl  n-dodecyl  79.6 11.8 5.5  3.0(III)-6  cyclohexyl cyclohexyl 77.1 9.9  8.2  4.7(III)-7  n-octadecyl             n-octadecyl                        81.1 12.3 4.1  2.3(III)-8  iso-dodecenyl             iso-dodecenyl                        78.2 11.7 5.5  3.0(III)-9  phenyl     phenyl     79.8 6.7  8.5  4.8(III)-10  octylphenyl             octylphenyl                        81.9 10.1 5.1  2.8(III)-11  n-octyloxy n-octyloxy 73.8 11.5 5.3  9.2  propyloxy  propyloxy(III)-12  benzyl     benzyl     80.4 7.2  7.8  4.4(III)-13  phenyl     n-octyl    78.9 9.0  7.6  4.3______________________________________ 
    
     
                       TABLE 5______________________________________Preparation of hydroxyquinoline derivativesrepresented by the formula IV ##STR9##          AnalysisCompound  R.sub.6    % C    % H    % N  % O______________________________________(IV)-14   nonylphenyl                78.0   8.2    7.8  5.9(IV)-15   2-ethylhexyl                75.1   8.2    9.4  7.1(IV)-16   octadecyl  77.6   9.7    7.2  5.4(IV)-17   cyclohexyl 74.6   7.6    10.0 7.6______________________________________ 
    
     EXAMPLES 17-34 AND COMPARATIVE EXAMPLES 3, 4 
     The hydroxyquinoline derivatives 1 through 17 obtained in Preparation Example 2 were added to a mineral oil and their performance as a metal inactivating agent was evaluated according to the foregoing copper plate corrosion test and oxidation test, the results of which are shown in Table 6. 
     
                       TABLE 6______________________________________Test Results               Test Results                 Copper                 Plate     Oxidation                 Corrosion TestMetal deactivator     Test      (minutes)______________________________________Exam- Hydroxyquinoline                (III)-1  1a      717ple 17 derivative18                   (III)-2  1a      60119                   (III)-3  1a      59020                   (III)-4  1a      58921                   (III)-5  1a      50122                   (III)-6  1a      31823                   (III)-7  1a      32324                   (III)-8  1a      34425                   (III)-9  1a      38126                   (III)-10 1a      32927                   (III)-11 1b      31928                   (III)-12 1a      47929                   (III)-13 1a      40130                   (IV)-14  1a      51131                   (IV)-15  1a      52632                   (IV)-16  1a      49133                   (IV)-17  1a      52334    (III)-1 + (IV)-14       1a      585 (50 wt % + 50 wt %)Com-para-tiveExam- None                    2a      234ple 3______________________________________ 
    
     The hydroxyquinoline derivatives according to this invention exhibited a superior performance in both copper plate corrosion test and oxidation test, and also in their application as lubricating oils such as turbine oil and hydraulic oil they showed a desirable performance.