LUBRICANT GREASE COMPRISING SPENT BLEACHING EARTHS
20260103655 ยท 2026-04-16
Inventors
Cpc classification
International classification
Abstract
A lubricant grease is described comprising at least one base oil, at least one main thickening agent, and optionally one or more additives comprising a second thickening agent in smaller quantities than said main thickening agent and a polymer additive, wherein said main thickening agent is one or more spent bleaching earths, and is present in a quantity up to 80%-90% by weight relative to the weight of the total composition of the grease, and wherein the base oil is fossil oil or oil of biological origin, renewable oil and/or biodegradable oil, or combinations thereof, preferably Group I mineral base oils (GPI), said lubricant grease being an infusible grease and classifiable according to the NLGI scale.
Claims
1. A lubricant grease comprising at least one base oil or mixtures of base oils, at least one first thickening agent, optionally, a second thickening agent, preferably in smaller quantities than the quantities of said first main thickening agent; and/or optionally, a polymer additive, possibly provided with water barrier properties, wherein said first thickening agent is one or more spent bleaching earths (SBE) and is present in a quantity from 10% up to 90% by weight relative to the total weight of the composition of said grease, and wherein said at least one or more base oils are fossil oils, synthetic oils, oils of biological origin, renewable oils and/or biodegradable oils, preferably except for UCOs (Used Cooking oils), or combinations thereof, said lubricant grease having a consistency classified according to the NLGI scale, said lubricant grease preferably being an infusible grease.
2. The lubricant grease according to claim 1, wherein when said second thickening agent is present no UCOs are provided among the base oils forming said lubricant grease.
3. The lubricant grease according to claim 1, wherein the content of spent bleaching earths (SBE) ranges from 10% to 80% by weight relative to the total weight of the lubricant grease composition, preferably from 20 to 80%, the remaining part to achieve 100% being capable of consisting only of one or more base oils, preferably excluding UCOs, or being capable of consisting of one or more base oils, preferably excluding UCOs, and one or more additives chosen from a second thickening agent, a polymer additive, possibly provided with water barrier properties, rust-preventing additives, anti-wear additives, antioxidant additives, copper corrosion inhibitors.
4. The lubricant grease according to claim 1, wherein said at least one base oil is a mineral base oil, preferably a base oil of API group I, or a mixture of mineral base oils, preferably mineral base oils of API group I.
5. The lubricant grease according to claim 1, wherein at least said base oil is a synthetic base oil or a mixture of synthetic base oils.
6. The lubricant grease according to claim 1, wherein the total quantity of spent bleaching earths ranges between 70 and 80% by weight, preferably around 75-76% by weight, relative to the total weight of the grease composition, the remaining part to achieve 100% being capable of consisting of one or more base oils, except for UCOs, or of one or more base oils except for UCOs and one or more additives chosen from rust-preventing additives, anti-wear additives, antioxidant additives, copper corrosion inhibitors.
7. The lubricant grease according to claim 1, wherein said polymeric additives, possibly provided with water barrier properties, is further included.
8. The grease according to claim 1, wherein said second thickening agent is also present, in a quantity ranging from 0.5% to 7% by weight, preferably in quantities ranging from 1% to 5% by weight, more preferably from 1.5% to 3-4% by weight, relative to the total weight of the lubricant grease composition.
9. The grease according to claim 8, wherein said second thickening agent is fumed silica.
10. The lubricant grease according to claim 1, comprising: 70-80% by weight, preferably 75-80% by weight of said spent bleaching earths; 10-30% by weight, preferably 18-25% by weight of one or more of said base oils, except for UCOs, preferably one or more mineral or synthetic oils, more preferably mineral oils; 0.5% to 7% by weight, preferably from 1.5 to 3-4% by weight, more preferably from 1.5 to 3% or from 3% to 4% by weight, of said second thickening agent, preferably fumed silica, the quantities of the aforesaid components being chosen so that their sum is 100%.
11. The lubricant grease according to claim 1, wherein said polymer additive, possibly provided with water barrier properties, is also included in quantities ranging from 1% to 35%, preferably from 7% to 35% by weight, relative to the total weight of the grease composition.
12. The lubricant grease according to claim 1, comprising: 50-55% by weight of spent bleaching earths; 10-22% by weight of base oil or a mixture of base oils, except for UCOs; 1.5-4% by weight of second thickening agent, preferably fumed silica, 7-35% by weight, preferably 10-32% by weight of a polymer additive, preferably polyisobutene, the quantities of each one of the aforesaid components being chosen so that their sum is 100% of the total weight of the composition, or the remaining part to achieve 100% of the total weight of the composition is capable of being represented by one or more further additives chosen from rust-preventing additives, anti-wear additives, antioxidant additives, copper corrosion inhibitors.
13. The grease according to any one of the preceding claims claim 1 wherein said spent bleaching earths are in neutralized form in terms of pH.
14. The grease according to claim 1, comprising (COMPOSITION C): SBE<75% by weight, preferably <60%; from 10% to 50% by weight of one or more base oils, preferably from 15% to 30-35% by weight; 0.5% to 7% by weight, preferably from 1.5 to 3-4% by weight of said second thickening agent, preferably fumed silica, <35% by weight of one or more further additives chosen from polymer additives, rust-preventing additives, anti-wear additives, antioxidant additives, corrosion inhibitors, the quantities of the aforesaid components being chosen so that their sum is 100%.
15. A process for preparing a lubricant grease as defined in claim 1, comprising at least the step of: mixing one or more spent bleaching earths with one or more base oils, preferably except for UCOs, at atmospheric pressure and at a temperature lower than or equal to 100 C.
16. The process according to claim 15, wherein said mixing takes place using an apparatus provided with high shear mixing means, preferably a mixing machine provided with a twin-screw mixer.
17. The process according to claim 15, wherein, before the mixing step of said SBE with said at least one base oil, the following steps are carried out: (1) optional homogenisation of the grain size of the spent bleaching earth (SBE) in order to remove possible non-homogeneities (lumps); (2) optional neutralisation of said spent bleaching earths with basic or acid substances; (3) loading of the spent bleaching earths into a mixing device, said spent bleaching earth having been optionally homogenised in terms of grain size and/or neutralised with basic or acid substances; (4) optional loading of one or more compounds capable to neutralise the pH of said SBE into the mixing device, if the spent bleaching earths loaded in step (3) have an acid pH or a basic pH, and optional removal of water, if present.
18. The process according to claim 15, wherein at the end of said mixing step of said one or more base oils and spent bleaching earths (SBE) there further are provided an optional subsequent addition step (5bis) to add a second thickening agent, e.g., fumed silica, while the mixture of components is being stirred until an homogenous mixture is obtained which has a cream-like look, or an homogeneous gel/paste is obtained; and an optional addition step (6) to add one or more further additives as defined in claim 1, after having increased the work temperature in the mixing device compared to the preceding steps, preferably up to at least 40 C., and maintenance of said mixing until a mixture having a cream-like look or a gel/paste-like look with no granules is obtained.
19. Use of infusible greases comprising spent bleaching earths as defined in claim 1 in the lubrication of moving mechanical members such as, preferably, bearings, in particular bearings with rotary elements, smooth bearings; gears, in particular open gears, which operate at high temperatures, for example over 200 C., in particular at temperatures that are typical for the processes of cement factories and of the iron and steel industry.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
[0103]
DESCRIPTION OF EMBODIMENTS
[0104] As mentioned above, the base oil employed in the lubricant grease of the present invention may be of different nature, in particular it may be chosen from the base oils of [0105] a fossil nature, for example a mineral oil (i.e. a mixture of hydrocarbons obtained starting from crude oil by means of a conventional refining process or by means of a medium hydrogenation process), of any viscometric cut (viscosity grade), for example a fluid cut (SN 125170 typically 150), a medium cut (SN 350600), a BrightStock (BS 150200) or mixtures thereof; [0106] of a synthetic nature, i.e. all types of base oils obtained by means of synthetic processes, for example by oligomerisation and hydrogenation of olefins, or polyol esters, such as for example PRIOLUBE 1965, PRIOLUBE 1963, or mixtures thereof; [0107] of a biological, renewable and/or biodegradable nature, for example palm oil, castor oil, microbial oil, or other oils indicated above for bio-charges preferably except for UCOs (WCO); polyalphaolefins functionalized with ester groups (PAO-esters) deriving from metathesis of vegetable oils;
or [0108] combinations thereof.
[0109] The spent oils UCO (Used Cooking oil) are preferably excluded as base oils for the lubricant grease of the present invention as these spent oils generally have carbonaceous residues, high freeze temperatures, corrosive compounds such as FFA (free fatty acids) and decomposition temperatures above 300 C., one or more of these characteristics representing an element of criticality both for obtaining a grease with a high drop point, i.e. greater than 350 C., and for the application of said grease containing UCO on the metallic surfaces, in particular steel surfaces, in view of the high continent of FFA which are corrosive for metals.
[0110] In the grease lubricant composition in accordance with the present invention when a second thickening agent is present, the UCOs are not present among the base oils forming the lubricant grease.
[0111] In addition, or as alternative to the above, when the base oil is UCO, the lubricating grease according to the present invention always includes the polymeric additive above defined.
[0112] As examples of mineral oil usable as base oil mention can be advantageously made of the mineral oils of API classification, preferably Group I (GPI), such as, for example, SN 500, BS 150, SN 150, BS 200 or mixtures thereof: the Group I oils advantageously allow the lubricant grease to achieve an NLGI class consistency of at least 1 but also higher.
[0113] As an alternative to the Group I mineral base oil, use can also be made of the API group II and/or group III mineral oils if it is wished to obtain a grease from mineral oils having a lower consistency according to the NLGI classification.
[0114] Examples of synthetic base oils employable in the lubricant greases of the present invention are the polyol esters (e.g. PRIOLUBE 1965, PRIOLUBE 1963) or mixtures thereof; polyalphaolefins (PAOs): generally said synthetic base oils belong to group IV of the API classification.
[0115] As examples of base oil of renewable origin employable in the lubricant greases of the present invention mention can be made of palm oil, castor oil, microbial oil, polyalphaolefins functionalized with ester groups (Pao-esters) deriving from metathesis of vegetable oils, estolides.
[0116] It is also possible to use group V base oils such as for example polymethacrylate, polyisobutene, but generally in admixture with a Group I, II, III or IV base oil.
[0117] In a preferred embodiment, said at least one base oil employed in the lubricant grease of the present invention is a mineral base oil and/or an oil of renewable source, preferably a mineral base oil of Group I, or a mixture of mineral base oils, preferably of mineral base oils of Group I (GPI), more preferably a mixture of SN 500 and BS 150.
[0118] The viscosity of the base oil of the lubricant grease of the present invention is not binding for the purposes of the present invention, but the higher the viscosity and the higher the NLGI consistency of the lubricant grease obtainable will be.
[0119] Kinematic viscosity values of base oils suitable for forming lubricant greases ranges, for example, between 50 and 800 mm.sup.2/s at 40 C., preferably between 100 and 600 mm.sup.2/s at 40 C.
[0120] The lubricant grease of the present invention may therefore be composed [0121] of one or more SBEs (non-purified or purified) and of one or more base oils (two-component grease), preferably except for UCOs; [0122] or it may comprise in addition to SBE (purified or non-purified) and one or more base oils preferably except for UCOs, also one or more additives chosen from a second thickening agent, a polymer additive capable of improving the structural stability of the grease, possibly provided with water barrier properties, other additives conventional for lubricating greases such as rust-preventing additives, anti-wear additives, antioxidant additives, copper corrosion inhibitor and the like, e.g. extreme pressure anti-wear additives such as for example graphite, as indicated below in detail.
[0123] In one embodiment, the lubricant grease, preferably infusible grease, is formed by [0124] spent bleaching earths as defined above for 70-80% by weight, preferably around 75%-76% by weight relative to the total weight of the grease composition, and [0125] by one or more base oils as defined above, preferably except for UCOs, for the remaining portion to achieve 100% by weight.
[0126] In another embodiment, this above-defined grease composition provides that the above remaining portion to 100% is constituted of a mixture of one or more base oils with one or more additives, preferably with a combination of additives (additive package) chosen from rust-preventing additives, anti-wear additives, antioxidant additives, copper corrosion inhibitors, extreme pressure anti-wear additives and optional stabilizers.
[0127] As already mentioned, in the lubricant grease of the present invention containing SBE and base oils it is advantageously present [0128] a polymer additive
and/or [0129] a second thickening agent other than the spent bleaching earths.
[0130] In one embodiment, the grease according to the present invention comprises at least the polymeric additive as above defined.
[0131] In one preferred embodiment, in the lubricating grease containing SBE and base oils according to the present invention it is advantageously present said polymeric additive and said second thickening agent different from the spent bleaching earths.
[0132] The second thickening agent, hereinafter also defined as thickening agent or viscosity modifier, is chosen from those conventionally used in the lubricant greases, such as for example fumed silica, preferably hydrophobic fumed silica, i.e. modified on the surface with polydimethylsiloxane, without particular limitations in terms of surface area, average particle dimension and grain size distribution.
[0133] Fumed silica, thanks to its three-dimensional structure, has a thixotropic behaviour increasing the viscosity when used as a thickening agent.
[0134] The quantity of such second thickening agent depends on the viscosity and/or consistency to be obtained for the final grease, in particular for the infusible grease: generally, the quantity of the second thickening agent may range from 0.5% to 7% by weight, preferably from 1% to 5% by weight with respect to the total weight of the lubricant grease composition.
[0135] In one embodiment, the amounts of said second thickening agent ranges from 1.5% to 3-4% by weight, relative to the total weight of the lubricant grease composition.
[0136] It is understood that quantities lower than 0.5% and greater than 7% of the second thickening agent may be employed without thereby departing from the scope of the present invention.
[0137] In one embodiment, the lubricant grease of the invention, preferably infusible grease, contains: [0138] 70-80% by weight, preferably 75-80% by weight, of spent bleaching earths as defined above; [0139] 10-30% by weight, preferably 18-25% by weight, of one or more base oils as defined above, except for UCOs, preferably one or more mineral oils; [0140] 0.5% to 7% by weight, preferably from 1.5 to 3-4% by weight, more preferably from 1.5 to 3% or from 3% to 4% by weight, of second thickening agent, preferably fumed silica, the quantities of the aforesaid components being chosen so that their sum is 100%.
[0141] If in the lubricant grease in accordance with the present invention one or more further additives are present, in addition to the indicated quantities of second thickening agent, the total content of SBE will generally be lower than 75% by weight, preferably lower than 60%: in such grease formulations furthermore the base oil or the mixture of base oils may advantageously range from 10% to 50% by weight, preferably from 15% to 30-35% by weight, relative to the total weight of the lubricant grease composition, and depends substantially on the grade of NLGI consistency to be achieved and on the total quantity of the further additives necessary for the grease formulation.
[0142] It is understood, however, that total quantities of base oil or of base oil mixture lower than 10% by weight relative to the total weight of the grease composition may be used in compositions in which one or more further additives are present in addition to the second thickening agent, without thereby departing from the scope of the present invention.
[0143] The one or more further additives, other than the second thickening agent, which can be used in the lubricant grease composition in accordance with the present invention, preferably in the infusible grease, are additives, which allow to achieve, if required, one or more conventional technical and performance specifications of the lubricant grease, including infusible greases, such as, for example: [0144] rust-preventing additives, in particular imidazolines, hemi esters of the succinic acid (e.g. carboxy-imidazoline marketed by AFTON under the name HITEC 536); [0145] anti-wear additives, such as dithiocarbamates (e.g. methylene-bis-dialkyl-dithiocarbamate marketed by RHEINE CHEMIE under the name RC 6340), dithiophosphates (e.g. dithiophosphate marketed by CIBA under the name: IRGALUBE 353), phosphorothionates, amino phosphates; [0146] antioxidant additives, in particular substituted diphenyl amines (e.g. octylated/butylated diphenylamine marketed by BASF under the name IRGANOX L 57); [0147] polymer additives, possibly provided with water barrier properties, to increase the structural stability of the gel, such as for example polyisobutene, polymethylmethacrylate, generally of low molecular weight (Mn), for example around 1300 g/mol; [0148] stabilizers; [0149] copper corrosion inhibitor such as for example benzotriazole derivatives, (e.g. mixture of N, N-bis(2-ethylhexyl)-4-methyl-1h-benzotriazole-1-methylamine+N, N-bis(2-ethylhexyl)-5-methyl-1h-benzotriazole-1-methylamine, marketed by CIBA under the name IRGAMET 39; and the like, such as for example extreme pressure anti-wear additives, e.g. graphite.
[0150] Generally, 1 content of further additives (other than the second thickening agent) in the lubricant grease is lower than or equal to 40% by weight, preferably lower than 35% by weight, relative to the weight of the total grease composition.
[0151] The quantity of each additive depends on the minimum quantity at which the specific performance for which the additive is used begins to take place: generally, quantities starting from 0.01% by weight, preferably from 0.1% by weight, of each additive relative to the weight of the total grease composition are to be considered minimum quantities, although larger quantities can be used without thereby departing from the scope of the present invention.
[0152] As already mentioned above, among the various additives usable in the lubricant grease, preferably infusible one, in accordance with the present invention compounds can be included that contribute to improving the structural stability of the grease such as polymer compounds, for example polyisobutene which is also advantageously provided with water barrier properties.
[0153] Other usable polymer additives are those belonging to group V of the API base oils and can be for example polyalkylmethacrylates, in particular VISCOBASE 5-220 (Kinematic viscosity at 100 C.=460-500 cSt), marketed by EVONIK.
[0154] Generally, the quantity of polymer additive, possibly provided with water properties, preferably polyisobutene, may ranges between 1-35%, preferably between 7% and 35%, preferably between 10 and 32% by weight relative to the total weight of the lubricant grease composition.
[0155] In one alternative embodiment, the quantity of polymer additive, possibly provided with water properties, preferably polyisobutene, may ranges between 1% and 7%, preferably between 1.5 and 4% by weight with respect to the overall weight of the composition of the lubricating grease.
[0156] The maximum quantity of each further additive (other than SBE, second thickening agent and polymer additive) may be about 5% by weight relative to the total weight of the grease formulation, although this is not binding for the purposes of the present invention.
[0157] In a preferred embodiment, the lubricating grease comprises the spent bleaching earths as above defined, the base oil (or mixture of base oils) as above defined, fumed silica as second thickening and polyisobutene as polymeric additive.
[0158] In another preferred embodiment, the lubricant grease comprises the spent bleaching earths as defined above, the base oil (or mixture of base oils) as defined above, the second thickening agent, e.g. fumed silica, and the polymer additive, e.g. polyisobutene, in the following quantities [0159] 50-55% by weight of spent bleaching earths; [0160] 10-22% by weight of base oil or of a mixture of base oils as defined above, except for UCOs; [0161] 1.5-4% by weight of second thickening agent, preferably fumed silica, [0162] 7-35% by weight, preferably 10-32% by weight, of polymer additive, preferably polyisobutene, [0163] the quantities of each one of the aforesaid components being capable of being chosen so that their sum is 100% of the total weight of the composition, or the remaining part to achieve 100% of the total weight of the composition being capable of being represented by one or more further conventional additives (additive package) for lubricant greases as indicated above chosen from rust-preventing additives, antioxidant additives, additives, anti-wear copper corrosion inhibitor, extreme pressure anti-wear additives and optionally stabilizers.
[0164] The lubricant grease of the present invention, preferably infusible grease, can therefore be formulated so as to have an NLGI consistency of class 0, or be formulated so as to have a greater consistency of class 1 or 2, but also higher for example 3, 4, by varying the concentrations of base oil, SBE, and of the other components (second thickening agent, polymer additive and other additives) without thereby departing from the scope of the present invention.
[0165] In a preferred embodiment, the lubricant grease is infusible and has a NLGI consistency of class greater than or equal to 1.
[0166] The lubricant grease of the present invention can therefore be formulated up to 80%-90% by weight with respect to its total weight from circular economy compounds with an important share of renewable material coming from the organic material present in the earths (about 30%), and from base oils of renewable origin for the remaining potential share to achieve 100%.
[0167] It has also been unexpected that the use of such spent bleaching earths results in a low water washout in the absence of additives known to confer water barrier properties, even in greases containing SBE as the sole thickening agent.
[0168] Some embodiments are infusible greases chosen from the following compositions (% by weight with respect to the overall weight of the composition of the lubricating grease):
Composition A:
[0169] from 10% to 80%-90% by weight of SBE, preferably from 70% to 80% by weight, more preferably from 75-80% by weight, relative to the total weight of the lubricant grease composition, [0170] the remaining portion to achieve 100% consisting only of one or more base oils as defined above, preferably mineral oils, except for UCOs.
Composition B:
[0171] 70-80% by weight, preferably 75-80% by weight of spent bleaching earths; [0172] 10-30% by weight, preferably 18-25% by weight of one or more base oils as defined above, except for UCOs; [0173] 0.5% to 7% by weight, preferably from 1.5 to 3-4% by weight, of second thickening agent, preferably fumed silica, [0174] the quantities of the aforesaid components being chosen so that their sum is 100%.
Composition C:
[0175] SBE<75% by weight, preferably <60%; [0176] from 10% to 50% by weight of one or more base oils, preferably from 15% to 30-35% by weight, [0177] 0.5% to 7% by weight, preferably from 1.5 to 3-4% by weight, of second thickening agent, preferably fumed silica, [0178] <35% by weight of one or more further additives chosen from polymer additives, rust-preventing additives, anti-wear additives, antioxidant additives, corrosion inhibitors, [0179] the quantities of the aforesaid components being chosen so that their sum is 100%.
Composition D:
[0180] SBE<75% by weight, preferably 50-55% by weight, [0181] from 10% to 50% by weight of one or more base oils as defined above, except for UCOs, preferably from 10% to 22% by weight, [0182] 0.5% to 7% by weight, preferably from 1.5 to 3-4% by weight, of second thickening agent, preferably fumed silica, [0183] 1-35% by weight, preferably 7-35% by weight, of polymer additive, preferably polyisobutene; [0184] <35% by weight of one or more further additives (additive package) chosen from rust-preventing additives, anti-wear additives, antioxidant additives, corrosion inhibitors, extreme pressure anti-wear additives, [0185] the quantities of the aforesaid components being chosen so that their sum is 100%.
Composition E:
[0186] 50-60% by weight of SBE, [0187] from 10% to 50% by weight of one or more base oils as defined above, except for UCOs, preferably from 10% to 35% by weight, [0188] from 1% to 4% by weight, of second thickening agent, preferably fumed silica, [0189] 1-5% by weight of polymer additive, preferably polyisobutene; [0190] <35% by weight of one or more further additives (additive package, e.g. conventional additive package) chosen from rust-preventing additives, anti-wear additives, antioxidant additives, corrosion inhibitors, extreme pressure anti-wear additives, e.g. graphite, [0191] the quantities of the aforesaid components being chosen so that their sum is 100%.
[0192] The process to prepare the lubricant greases of the present invention, preferably infusible greases, comprises at least the following step of: [0193] mixing at least one or more spent bleaching earths as defined above with at least one or more base oils as defined above, preferably except for UCOs, at atmospheric pressure and at a temperature lower than or equal to 100 C., preferably under ambient temperature conditions.
[0194] Mixing can take place in any apparatus provided with mixing and/or stirring devices suitable for mixing semi-solid and extremely viscous products so as to obtain a workable mixture, such as apparatuses provided with mixing means with a high shear stress such as, for example, planetary mixing machines, propeller mixing machines, mixing machines provided with a twin-screw mixer, preferably a mixing machine provided with a twin-screw mixer.
[0195] Examples of stirring/mixing speeds can be speeds from 40 rpm up to 1200 rpm.
[0196] This preparation modalities which envisages a simple mixing, for example in a mixing machine, offers a great advantage over the preparation of the bentonite greases for which much more complex modes are envisaged: mixing temperatures higher than 100 C. and high work pressures, generally around 30 bar but also beyond, for example up to 200 bar, to carry out homogenisation.
[0197] The use of mixers with a twin-screw mixer has proved to be particularly advantageous as an infusible grease was obtained simply by using spent bleaching earths for 75-80% by weight of the lubricant grease, without resorting to a second thickening agent, as such fumed silica, conventionally used in the bentonite greases.
[0198] The greases of the invention thus obtained have unexpectedly also shown excellent properties of water washout resistance (even in the absence of additives also provided with water barrier properties, e.g. polyisobutene), infusibility and protection of the metals (e.g. copper, steel) against corrosion given by having passed the Emcor test (test on steel) in addition to the passing of the test on copper.
[0199] Moreover, the lubricant greases of the invention have shown a very high adhesiveness, generally higher than that of the known bentonite greases: high adhesiveness is in fact advantageous since it guarantees that the grease remains in the seat when it is subjected to the dynamic stresses during the operations.
[0200] In addition, a high adhesiveness allows to limit the centrifugation loss of grease which is typical in some applications, e.g. gearmotors.
[0201] In particular, the process of preparation is carried out advantageously by effecting, before the mixing step of SBE+base oil, a neutralization step of the pH of said spent bleaching earths.
[0202] More in particular, the preparation process advantageously takes place by preceding the SBE+base oils mixing step, with the following steps: [0203] (1) optional homogenisation of the grain size of the spent bleached earths so as to make the grain size uniform, for example by means of a mill, in order to remove any non-homogeneities, such as for example lumps, agglomerates or the like generated by the presence of water and bio-charge adsorbed on the spent bleaching earths; [0204] (2) optional neutralisation of the pH of said spent bleaching earths by using basic or acid substances; [0205] (3) loading of said spent bleaching earths into the mixing device, said spent bleaching earths being possibly previously homogenised and/or made uniform in terms of grain size, and/or optionally neutralised with basic or acid substances, where said loading can take place through the use, for example, of a conveyor auger; [0206] (4) optional loading of one or more neutralising compounds into the mixing device if the spent earths loaded in step (3) have an acid pH, e.g. 5.5, or a basic pH, e.g. 9, for example by the addition of an aqueous solution containing 10-35% by weight of inorganic basic substance, e.g. Ca(OH).sub.2, or of inorganic acid substance, and any removal of water if present.
[0207] Step (4) is preferably carried out when the SBEs have not previously undergone the neutralisation treatment of step (2): it is however understood that step (4) may be carried out even if step (2) has already been performed, without thereby departing from the scope of the present invention.
[0208] Next, it is proceeded with the step of adding one or more base oils under stirring and mixing SBE+base oils, hereinafter referred to as step (5), at the end of which it is envisaged [0209] an optional subsequent addition step (step 5 bis) to add a second thickening agent, e.g. fumed silica, while the mixture of components is being stirred, until an homogenous mixture is obtained which has a cream-like look, or an homogeneous gel/paste is obtained, e.g. by continuing to stir for 4 hours;
and [0210] an optional addition step (6) to add one or more further additives as indicated above, after having increased the work temperature in the mixing device compared to the preceding steps, preferably at least to 40 C., more preferably to 60 C., and while mixing until a mixture is obtained without granules which has a cream-like look or looks like a gel/paste, e.g. by continuing to stir for 1 hour.
[0211] The above steps (1) to (6) take place at atmospheric pressure. In addition, the above steps (1) to (5 bis) take place at ambient temperature.
[0212] In one embodiment, the step (1) of homogenising the grain size is advantageously carried out, even if there are visually no lumps, so as to be sure that the SBEs are uniform in terms of grain size before giving rise to the lubricant grease.
[0213] In another embodiment, the neutralisation step (2) and/or (4) is advantageously carried out to avoid possible corrosions to the production plant.
[0214] The advantages of the lubricant greases of the present invention obtained with the above-described process in accordance with the invention are manifold with respect to the known art.
[0215] A first advantage consists in the reuse of the spent bleached earths in far greater quantities than the quantity of bentonite used to produce lubricant greases (e.g. in percentage >>50%) unlike bentonite greases in which the percentage of use of bentonite is 8-10% max.
[0216] A second advantage is the reuse of the spent bleaching earths as such, without needing for posttreatment of the same, except for the possible neutralisation of their pH for reasons of corrosion of the materials of the plant.
[0217] Another advantage is the production process that is simple and simplified compared to that of the bentonite greases as it operates at atmospheric pressure, instead of under pressure, and at temperatures lower than 100 C.
[0218] Furthermore, the process adopted in the present invention for the production of lubricant greases allows the improvement of some performance characteristics, for example the water washout, and an improved resistance to water penetration compared to the bentonite greases on account of the absence of weight increase due to water incorporation: these properties advantageously allow the use of the lubricant greases of the invention in humid environments and/or in the presence of water.
[0219] Some illustrative but not limiting examples of the present invention follow.
[0220] In the following examples the physical properties have been determined with the specified standard methods but it is understood that it is possible to measure the same physical properties with equivalent methods belonging to different norms/standards without thereby departing from the scope of the present invention.
EXAMPLES
Material
[0221] PRIOLUBE 1965: polyol ester, marketed by Croda, and having a kinematic viscosity at 40 C. equal to 220 cSt; [0222] PRIOLUBE 1963: polyol ester, marketed by Croda, and having a kinematic viscosity at 40 C. equal to 220 cSt; [0223] Fumed silica: CAB-0-SIL TS 720 by Cabot, surface modified with polydimethylsiloxane that makes it hydrophobic; [0224] PB 300 (thus indicated for brevity's sake): INDOPOL H-300 additive (POLYBUTENE H 300) having a molecular weight (Mn) of 1300, marketed by INEOS as a polymer additive (oligomer); [0225] BS 150: mineral base oil marketed by ENI SpA; [0226] SN 500: mineral base oil marketed by ENI SpA; [0227] Type 1 spent bleaching earths (coming from the ENI SpA plant in Venice for the bleaching treatment of palm oil) obtained from acid activated bentonite TONSIL 9194 FF marketed by Clariant: waste in the form of a non-powdery solid containing about 287 g/kg (28.7%) of animal and vegetable Oils and greases; C12+ heavy hydrocarbons: about 540 mg/kg; mineral oils: about 580 mg/kg; metals around 5 g/kg; phosphates and sulphates around 2.9 g/kg; [0228] Type 2 spent bleaching earths (sample coming from the ENI SpA plant in Gela for the treatment of bio-charges) obtained from acid activated bentonite TONSIL 9194 FF marketed by Clariant: waste in the form of a non-powdery solid and containing animal and vegetable Oils and greases, C12+ heavy hydrocarbons, metals, phosphates and sulphates in quantities similar to SBEs type 1 from the plant in Venice.
Characterisations/Analysis Method
Drop Point
[0229] It is the temperature at which a grease sample, if heated, starts flowing through an opening according to the method ASTM D566.
CONSISTENCY after 60 Double Strokes (Dc)
[0230] It is the measurement of the stiffness of a grease and is evaluated by measuring the degree of penetration according to ASTM D217-21a (10 mm). The test measures in tenths of mm at which depth of a sample of grease a given cone sinks.
[0231] The consistency is classified according to a scale developed by NLGI (National Institute of Grease Lubrication) and reported hereinbelow: the greases for bearings are normally NLGI 1, 2 or 3, and the softer the grease, the lower the number.
TABLE-US-00001 NLGI CONSISTENCY TABLE Appearance NLGI ASTM Penetration at ambient number grade (10.sup.1 mm) temperatures 000 445-475 very fluid 00 400-430 Fluid 0 355-385 semi-fluid 1 310-340 very soft 2 265-295 Soft 3 220-250 medium dense 4 175-205 Dense 5 130-160 very dense 6 85-115 extremely dense
Water Washout
[0232] The measurement is made in accordance with the method ASTM D 1264: the test (Water washout) envisages coating a ball bearing placed in a housing with a grease. Thereafter, the bearing is rotated at 600 rpm and subjected to water jet at a temperature of 38 C. for one hour. At the end of the test, the bearing is dried in the stove for 16 hours and then weighed to check for any weight loss (% by weight) due to water washout of the grease.
Copper Corrosion
[0233] Evaluated by subjecting a sample of grease of the invention to the test according to ASTM D 4048.
Kinematic Viscosity
[0234] Evaluated at 40 C. according to the method ASTM D445.
Example 1
Formation of an SBE Gel/Base Oil and Evaluation of the Drop Point
[0235] In order to evaluate the effective formation of a gel from the spent bleaching earths and to verify the formation of an infusible lubricant grease, it was proceeded with mixing a considerable quantity of a sample of spent bleaching earths with a base oil formed by a mixture of esters, PRIOLUBE 1965 and PRIOLUBE 1963, in relative quantities as reported in table 1.
[0236] Said base oil consisting of the mixture of esters has a kinematic viscosity at 40 C. equal to 220 cSt.
[0237] The sample of spent bleaching earths (hereinafter referred to as type 1 spent earths) that comes from a bleaching treatment of a bio-charge consisting of palm oil, was mixed as such, at ambient temperatures and pressure, with the aforesaid base oil in the percentages indicated in Table 2.
[0238] The spent bleaching earths used (of type 1-sample CER020304) show a pH equal to 3.2 evaluated in an aqueous solution containing 10% by weight of said spent earths.
TABLE-US-00002 TABLE 1 Ester mixture % by composition weight PRIOLUBE 1965 46 PRIOLUBE 1963 54
TABLE-US-00003 TABLE 2 % by Composition of the lubricant weight Spent bleaching earths 80 PRIOLUBE 1965 + PRIOLUBE 1963 20
[0239] The preparation of the gel was carried out according to the following procedure: to the type 1 spent bleaching earth, placed in a becker under a hood, addition is made of the base oil (mixture of ester bases) at ambient temperature and atmospheric pressure, under stirring starting from a speed of 40 rpm up to 1200 rpm for 1 hour.
[0240] The mixer used is a laboratory mechanical mixer, ICA RW 16 BASIC.
[0241] A gel with an appearance as shown in
TABLE-US-00004 TABLE 3 Characteristics of the gel Result Method NLGI consistency after 60 dc 0 ASTM D 217 Drop point, C. >350 ASTM D 566
[0242] The drop point higher than 350 C. and the consistency of the final composition belonging to the NLGI scale of the lubricant greases (grade 0, corresponding to a semi-fluid appearance) attest to the effective formation of a lubricant grease with a gel structure that retains the oil, given the high drop point.
[0243] This means that the network formed by the spent bleaching earths is very resistant and prevents the outflow of the base oil retained inside it, in a way similar to what happens in infusible bentonite greases.
Example 2
Preparation of Infusible Greases Containing SBE and Fumed Silica
[0244] Using the same type 1 spent earths, three lubricant grease formulations (formulation 2, formulation 3 and formulation 5) were prepared in accordance with the present invention, the compositions of which are reported in table 4.
[0245] The procedure followed for the preparation of the greases and the apparatus are the ones reported in example 1, except for the subsequent addition, after 1 hour of stirring, of the fumed silica keeping the composition under stirring.
[0246] Gels were obtained with an appearance as shown in
TABLE-US-00005 TABLE 4 Formulation No. 2 3 5 Gel composition (% by weight) Spent EARTHS (SBE) 76 76 80 Mixture of esters 24 22.5 18.5 Fumed silica 1.5 1.5 Characteristics of the gel NLGI consistency 0 (365 dmm) 1 (340 dmm) 2/1 (305 dmm) after 60 dc Drop point, C. >350 >350 >350
[0247] As can be noted from table 4, the addition of fumed silica allows the gel to harden, obtaining a harder grease, passing from a 0 consistency to a 1 consistency.
[0248] Then slightly increasing the quantity of spent earths SBE further increased the consistency.
[0249] In general, the greater the consistency of the grease and the greater the ability of the grease to remain in the bearing without generating excessive friction.
Example 3
Preparation of Infusible Greases with Neutralised Spent Earths
[0250] By repeating the procedure of example 2 and using the same type 1 spent earths and the same mixture of esters as the base oil, lubricant grease formulations containing basic substances were prepared.
[0251] Considering that the acid pH of the type 1 spent earths (having a pH equal to 3.2 in a 10% by weight aqueous solution of SBE) in the presence of water could favour the corrosion of the metals, three grease formulations were prepared by adding, with respect to example 2, different basic substances in aqueous solution, as reported in table 6, so as to have the neutralisation of the pH of the SBEs.
[0252] The addition of the basic substance, in the form of an aqueous solution, was carried out after the addition of base oil in the formulation.
[0253] Subsequently, the water was removed from the product obtained by means of heating in the stove at 100 C. for 1 hour.
[0254] The basic substances, in 10% aqueous solution, which were added in the formulation are the following ones [0255] PROPLENCARBONATE (formulation 6) [0256] CALCIUM HYDROXIDE (formulation 7) [0257] CALCIUM CARBONATE (formulation 8)
[0258] Gels were obtained with an appearance as shown in
TABLE-US-00006 TABLE 5 Formulation No. 5 6 7 8 Gel composition (% by weight) Spent EARTHS 80 79.2 79.9 79.7 Mixture of esters 18.5 18.5 18.5 18 Fumed silica 1.5 1.5 1.5 1.5 Aq. Sol. at 10% of 0.8 0.1 0.8 basic substance Characteristics of the gel pH at 10% of gel in 3.5 4.7 3.7 6.3 aqueous solution NLGI consistency 2/1 (305) 1 (309) 2 (267) 2 (291) after 60 dc dmm Drop point, C. >350 >350 >350 >350
[0259] The pH of the formulation 8 is close to neutrality: the quantity of basic substance in the formulation is such that no worsening of the consistency and drop point characteristics of the grease is noted compared to formulation 5 which is not added with basic substances and has an acid pH.
Example 4
Preparation of Infusible Greases Using a Base Oil of Mineral Type, Fumed Silica and a Polymer Additive with Water Washout Test
[0260] Example 2 was repeated using the same type of spent earths (type 1, Venice) except for using different base oils and for the addition of a further conventional polymer additive of polymer nature such as polyisobutene 300, indicated as PB 300 for brevity's sake.
[0261] A mixture of API Group I mineral base oils having substantially the same viscosity (at 40 C.) as the mixture of ester base oils of examples 2 and 3 was used as the base oil.
[0262] The mixture of mineral base oils employed in this example has a kinematic viscosity at 40 C. equal to 220 cst (ASTM D455) and has the following composition
TABLE-US-00007 Mineral base oil composition % by (mixture of mineral base oils) weight SN 500 46 BS 150 54
[0263] The preparation modalities of the various lubricating gels are identical to those employed in the previous examples 1-3 with the ester base oils.
[0264] In one of the formulations (formulation 16) it was proceeded with neutralising the spent bleaching earths before their formulation with the other components of the grease instead of during the formulation of the grease itself, using 3 g of Ca(OH).sub.2 conveyed in a minimum quantity of water so as to bring the pH of the spent bleaching earths to neutrality when present at 10% in aqueous solution.
[0265] The spent earths employed in formulations 12, 13, 14 were not neutralised either during the formulation of the grease or prior to formulation.
[0266] Gels were obtained with an appearance as shown in
TABLE-US-00008 TABLE 6 Formulation No. 12 13 14 16 Gel composition (% by weight) Spent EARTHS (non- 50 50 50 neutralised) Spent earths neutralised with 50 Ca(OH).sub.2 (before formulation) Mixture of mineral oils 32 22 15 15 SN500/BS 150 Fumed silica 3 3 3 3 PB 300 15 25 32 32 Characteristics of the gel pH at 10% of gel in aq. sol. 3.5 3.5 3.5 6.9 NLGI consistency after 60 dc 1 (340) 1/0 (347) 1/0 (350) 1 (329) dmm Drop point, C. >350 >350 >350 >350 Water washout 8.25 7.5 5.25 6.5
[0267] The above reported data show that the infusible greases in accordance with the present invention have excellent values of water washout resistance.
Example 6
Preparation of Infusible Greases Containing Additives and a Different Type of Neutralised Spent Bleaching Earths (Earths Sample 2)
[0268] A sample of spent bleaching earths (SBE) coming from a different bleaching treatment plant than that indicated in example 1 (hereinafter referred to as type 2 spent earths), having a pH equal to 3.15 (measured in an aqueous solution containing 10% by weight of SBE) were pre-treated before being formulated with the other components of the lubricant grease, bringing the pH of the aqueous solution containing 10% by weight of SBE to the value of 7 by mixing with an aqueous solution of Calcium hydroxide at 33% by weight. The final composition of the earths used is as follows
TABLE-US-00009 % by Composition of the lubricant weight Spent bleaching earths 88.5 Aq. Sol. of Ca(OH).sub.2 at 23% 11.5 pH of the spent bleaching 7 earths in 10% aqueous sol.
[0269] Employing the same mixing procedure described in the previous examples, the neutralised spent bleaching earths were then formulated with mineral base oils SN 500/BS 150 employed in the previous examples, and with additives (fumed silica and PB 300) already employed in the previous examples.
[0270] Mixing was carried out using in some cases a laboratory planetary mixer and in other cases mixing machines provided with a twin-screw mixer (ERWECA AR 402 200 g and Battagion 2 kg models).
[0271] Gels were obtained with an appearance as shown in
TABLE-US-00010 TABLE 7 Formulation No. 17 18 19 Gel composition (% by weight) Spent EARTHS neutralised 50 50 55 with Ca(OH).sub.2 Mixture of mineral oils 15 15 10 SN 500 + BS 150 Fumed silica 3 3 3 PB 300 32 32 32 Characteristics of the gel NLGI consistency after 1 (337) 0 (370) 1 (340) 60 dc dmm Drop point, C. >350 >350 >350 Water washout (% by weight) 7.5 7.5 9.25 pH 10% gel in aqueous sol. 7 7.5 6.9 Mixing means Planetary Propeller Twin-screw mixer mixer mixer
Example 7
Infusible Grease Also Containing a Package of Conventional Additives
[0272] Formulation 19 of Example 6 was subsequently added with a standard package of f additives widely used in the formulation of industrial lubricants, which comprises antioxidants, rust-preventing, anti-wear and copper corrosion inhibitor as defined hereinbelow.
[0273] The addition of the package of additives to formulation 19 was carried out using a twin-screw mixing machine.
[0274] The package of additives is composed as follows: [0275] Antioxidant: IRGANOX L 57 from BASF (octylated/butylated diphenylamine); [0276] Rust-preventing: HITEC 536 from AFTON (carboxy-imidazoline); [0277] Antioxidant/anti-wear: RC 6340 from RHEINE CHEMIE (methylene bis-dialkyl-dithiocarbamate); [0278] Anti-wear extreme pressures: IRGALUBE 353 (dithiophosphate) and IRGALUBE 211 (triphenyl nonylate phosphorothionate) from CIBA; [0279] Copper corrosion inhibitor: IRGAMET 39 from CIBA (N, N-bis(2-ethylhexyl)-4-methyl-1h-benzotriazole-1-methylamine+N, N-bis(2-ethylhexyl)-5-methyl-1h-benzotriazole-1-methylamine).
[0280] Table 8 reports the final composition (considered 100%) after the addition of the package of additives with the percentage of the components in the final grease.
TABLE-US-00011 TABLE 8 Gel composition (% by weight) Formulation No. 19_a Neutralised spent EARTHS 52.1 Ca(OH).sub.2 1.45 Mixture of mineral 9.7 oils SN 500 + BS 150 Fumed silica 2.9 PB 300 31.2 Package of additives 2.65
[0281] The grease thus obtained, with the appearance of a gel as shown in
TABLE-US-00012 TABLE 9 Grease characterization formulation 19_a Features Method UM Result Appearance visual cream-like, without granules Colour visual anthracite NLGI consistency 0 (before the test) Penetration after 60 dc ASTM D 217 dmm 361 Drop point ASTM D 566 C. >350 Oxidation @ 99 C. ASTM D 942 after 100 hours psi 18.64 after 500 hours psi 91.08 Water washout @ 38 C. ASTM D 1264 wt. % 9.9 Roll Shell Stability ASTM D 1831 Penetration variation = dmm 6 P.sub.final P.sub.initial NLGI consistency at the 0 end of the test EMCOR test in H.sub.2O dist. IP 220 merit 1/1 (two-way repeated test) Torque test @10 C. ASTM D 1478 starting torque mN .Math. m 137.0 operating torque mN .Math. m 87.2 Torque test @20 C. ASTM D 1478 starting torque mN .Math. m 408.0 operating torque mN .Math. m 258.0 Flow pressure DIN 51805-2 at 0 C. hPa 538.0 at 10 C. hPa 1125.0 Wheel Bearing ASTM D 1263 Grease loss wt. % 3.80 4 EP balls ASTM D 2596 Max load in absence of kgf 80 seizure Welding load kgf 200 4 WEAR balls ASTM D 2266 Wear Diameter mm 0.90 Specific pressure MN/m2 256
[0282] As can be observed, the infusible grease obtained in accordance with the present invention has a combination of properties such as: [0283] excellent resistance to water washout and absence of increase of weight due to water incorporation. The bentonite greases subjected to the test have a weight increase by about 20% due to water incorporation, a phenomenon not observable in the grease of the present invention as reported in the following table 10
TABLE-US-00013 SPENT BLEACHING BENTONITE BENTONITE EARTH GREASE GREASE 1 GREASE 2 (ex. 19_a) NLGI 2 3 0 consistency WATER +19.25 +19 9.9 WASHOUT RESISTANCE, wt. % [0284] Bentonite grease 1: product marketed by Eni under the name GREASE NF 2; [0285] Bentonite grease 2: product marketed by Eni under the name GREASE 33 FD. [0286] The increase of weight of the bentonite greases due to water incorporation could alter the chemical-physical and rheological characteristics of the grease, favouring corrosion phenomena and the oxidation of the grease itself. [0287] good rust-preventing response confirmed by the excellent result of the Emcor test in distilled water given by the merit value 1 which corresponds to a condition in which there are no more than three corrosion points and none of which has a diameter greater than 1 mm. The merit classes of the test are decreasing and range from 0 (no corrosion) to 5 (severe corrosion). [0288] This is a particularly significant test developed by SKF to verify the ability of a grease to protect the bearing from rust formation: the more the grease has this property, the more the operating hours of a bearing will be. [0289] Good cold properties despite the presence of the polyisobutene polymer (at low temperatures its viscosity tends to increase and hinder the sliding of the grease) which attest to how the grease can be used at low temperatures up to 10 C.: this property is measured by the torque test. A bearing, filled with grease, is cooled up to a given temperature at which the torque necessary for the rotation of the bearing is measured, overcoming the resistance of the grease. The results of the test are expressed by two numbers, one is the maximum value recorded at the beginning of the test, the other a continuous stationary torque once the continuous speed is reached. The higher these values, the lower the grease performance at the test temperature. [0290] The test is passed when the starting torque 1000 mN.Math.m, and/or operating torque100 mN.Math.m: at 10 C. the values obtained fall within the limits of the ISO 12924 grease specification, at 20 C. the operating torque is higher than the limit. [0291] The good cold properties of the grease in accordance with the present invention are also highlighted by the minimum operation temperature given by the values obtained with the flow pressure test, in which the pressure necessary to let a grease to flow at low temperatures is determined. The results obtained at 0 C. and at 10 C. are both below the limit reported by ISO 12924 indicated as 1400 hPa. [0292] Excellent resistance to processing attested by the roll shell stability, in which the lubricant grease sample is placed in a cylinder containing a roller and rotated for 2 hours at 35 C. The grease in question maintains the same initial consistency even after processing.
[0293] The loss in weight of grease from the bearings in operation was also evaluated by means of a wheel bearing test, which in any case gives an important indication of the tendency of the grease to exit from the seat. In this case the value obtained is good.
[0294] Finally, it is important to note that in general the addition of additives softens the grease, and therefore if it is wished to obtain a grease of high consistency, for example NLGI 2, it is important to start from a gel (spent bleaching earths+base oil) of higher consistency.
Example 8
Preparation of Infusible Greases with a Higher Content of Type 2 Spent Earths and with Base Oils of Different Viscosity ISO VG
[0295] By repeating the procedure of example 6 (with the same type of twin-screw mixer), three infusible greases were prepared using the same type of neutralised spent earths but in higher percentages (75%) than in example 6, formulating them with three base oils with increasing viscosity formed by three different mixtures having different viscosities (ISO VG 320, ISO VG 220 and ISO VG 100), thus composed
TABLE-US-00014 Mineral bases ISO VG 100 ISO VG 220 ISO VG 320 SN 500, wt. % 94 46 25 BS 150, wt. % 6 54 75
[0296] Gels were obtained with an appearance as shown in
TABLE-US-00015 TABLE 10 Formulation No. 22 23 24 Gel composition (% by weight) Spent EARTHS neutralised with 3 gr 75 75 75 Ca(OH).sub.2 Mixture of mineral oils SN 500/BS 150 ISO 25 Mixture of mineral oils SN 500/BS 150 ISO 25 Mixture of mineral oils SN 500/BS 150 ISO 22 Fumed silica 3 Characteristics of the gel NLGI consistency after 60 dc dmm 4 (171) 4 (194) 3 (219) Drop point, C. >350 >350 >350 Water washout 11 9 7.5 pH at 10% gel in Aqu. sol. 7.01 7.1 7.3 Copper corrosion, merit (two-way test) 1B/2A
[0297] As can be noted, with the same content of spent bleaching earths it is possible to achieve consistency and consequently higher NLGI classes if base oils or mixtures of base oils with increasing viscosity are used.
[0298] Furthermore, it is possible not to employ conventional additives to increase water resistance when employing high quantities of spent bleaching earth, for example greater than 50%, while at the same time achieving an NLGI grade greater than 1.
[0299] In particular, the grease in accordance with the invention of formulation 24 shows, in addition to infusibility and high content of spent bleaching earths, the following characteristics: [0300] high consistency [0301] high water washout resistance in the absence of additives; [0302] excellent compatibility with copper (1B: the greater the number and the worse the merit, i.e. the corrosion resistance) despite not containing the specific corrosion inhibitor.