New additive mixtures

Abstract

The invention relates to a new additive mixture, to a process for its production and to its use for turbine oils.

Description

Technical Field

[0001] This invention relates to novel additive mixtures, their production methods, and their use in turbine oils. Background Technology

[0002] Turbines (such as steam turbines, gas turbines, and water turbines) are typically used to convert kinetic energy into electrical energy. Effective turbine oil as a lubricant is essential for uninterrupted operation. In this case, the ability to provide reliable lubrication at high operating temperatures for a relatively long period is crucial.

[0003] Suitable turbine oils for general applications possess a range of desirable properties to account for the diverse operating conditions of various types of modern industrial turbines. These properties include, for example, a high viscosity index (VI), high oxidation stability (and the associated long service life), low coating / sludge formation, good water separation capabilities, improved rust and / or corrosion resistance, and improved air release and foaming properties.

[0004] For example, EP-A1730101 discloses an additive for turbine oils containing nonyl- / dinonyl- or styrene-substituted N-α-naphthyl-N-aniline and nonyl- / dinonyl- or styrene-substituted diphenylamine as antioxidants.

[0005] In particular, octyl-substituted N-α-naphthyl-N-aniline is being used more and more often, either alone or in combination with various additives, such as US-A 5726135. The disadvantage of these additives is that they have poor solubility in mixtures with other additives, and a relatively large amount of solubilizer is required to obtain liquid additive mixtures.

[0006] WO 2019 / 183187, EP-A 3712235, and EP-A 2307535 disclose, for example, turbine oils containing one or more antioxidants derived from the group consisting of N-α-naphthyl-N-aniline and diphenylamine, as well as sulfur-containing additives as additional components. Sulfur-containing compounds are known to improve the oxidative stability of lubricants, as confirmed by the Rotating Pressure Vessel Oxidation Test (RPVOT, ASTM D 2272) and the Oxidative Corrosion Test according to ASTM D 4636. Examples can also be found in WO 2019 / 183187. However, many sulfur-containing compounds tend to form sludge, which adversely affects the results of other oxidation tests, such as the dry TOST test according to ASTM D 7873. Summary of the Invention

[0007] The object of the present invention is to provide an improved additive mixture that can be used as a turbine oil, particularly in combination with a base oil, which meets the requirements of the oxidation test according to ASTM D 7873 and is intended to pass the corrosion and oxidation test according to ASTM D 4636.

[0008] It has now been unexpectedly discovered that this objective can be achieved using an additive mixture containing one or more C... 10 -C 14 Alkyl-substituted N-α-naphthyl-N-aniline (APAN), alkyl-substituted diphenylamine (DPA), at least one from C8-C 12 Sulfur-containing compounds of alkyl-substituted 2,5-dimercapto-1,3,4-thiadiazoles, as well as benzotriazole derivatives. Detailed Implementation

[0009] This invention provides an additive mixture comprising:

[0010] (a) One or more alkyl-substituted N-α-naphthyl-N-aniline (APAN) of formula (I)

[0011]

[0012] Where R1 = C 10 -C 14 Alkyl, preferably C 10 -C 12 alkyl,

[0013] (b) One or more alkyl-substituted diphenylamines (DPA) of formula (II)

[0014]

[0015] Wherein R2 to R5 are independently equal to H, C4-C9 alkyl, preferably C4 alkyl and / or C8-C9 alkyl, provided that at least one of R2 to R5 is a C8 or C9 alkyl group.

[0016] (c) at least one sulfur-containing compound of formula (III)

[0017]

[0018] And R = C8 - C 12 Alkyl, preferably C9H 19

[0019] as well as

[0020] (d) at least one benzotriazole of formula (IV)

[0021]

[0022] In (e) optional oil.

[0023] Component (a): C in the context of this invention 10 -C 14 Alkyl-substituted N-α-naphthyl-N-aniline (APAN) (a) is preferably a compound of formula (I), wherein R1 = C 10 -C 14 Alkyl groups, wherein at least 80% by weight of the groups are C14. 10 -C 12 Alkyl groups, particularly C4 groups 12 Alkyl group. The preferred position of group R1 is at the para position. In another preferred embodiment of the invention, component (a) consists of 80% monoalkylated C 11 and C 12 Alkyl groups.

[0024] Component (b): In the context of this invention, the alkyl-substituted diphenylamine (DPA) (b) is preferably a mixture of compounds of formula (II), wherein groups R2-R5 correspond to one, two, or three C4 or C8 alkyl groups in total. It is particularly preferred here that the mixture of compounds of formula (II) consists of 90% by weight of the compounds, wherein R2 and R3 are C4 or C8 alkyl groups.

[0025] Component (c): In the context of this invention, the sulfur-containing compound (c) is preferably a C9 alkyl-substituted 2,5-dimercapto-1,3,4-thiadiazole.

[0026] Component (d): In the context of this invention, benzotriazole (d) is preferably N,N-bis(2-ethylhexyl)-methyl-1H-benzotriazole-1-methylamine (wherein the methyl group is at position 4, 5, or 6) and / or N,N-bis(2-ethylhexyl)-methyl-2H-benzotriazole-1-methylamine (wherein the methyl group is at position 4 or 5). The above-mentioned benzotriazole is preferably used as a mixture of 1H-benzotriazole and 2H-benzotriazole in a ratio of 60%-70% (1H) and 40%-30% (2H) by weight.

[0027] Component (e): In the context of this invention, oil (e) can be mineral oil, synthetic oil, or a mixture thereof. There are no particular limitations on the type of mineral oil or synthetic oil. However, mineral oils or synthetic oils with a kinematic viscosity of 10-25 cSt at 40°C are generally used. Examples of mineral oils include paraffinic mineral oils, intermediate mineral oils, and naphthenic mineral oils, as well as synthetic oils or acyclic hydrocarbons.

[0028] Component (f): In a preferred embodiment of the invention, the additive mixture contains at least one corrosion inhibitor, particularly preferably carboxylamide (f).

[0029] In the context of this invention, carboxylamides, preferably amides of carboxylic acids having 4-50 carbon atoms, such as N-oleoylsarcosine or succinamide, can be used as corrosion inhibitors (f).

[0030] Carboxylamides (f) based on aspartic acid are preferred; compounds having the following formula are particularly preferred.

[0031]

[0032] Among them, R6, R9-R 12 Independently = H or C1-C 30 alkyl,

[0033] R7 and R8 are independent of each other = H, C1-C 30 Alkyl, C1-C 30 Acyl group, C1-C 30 Alkyl group; preferably, R7 is C1-C 30 Acyl group and R8 is C1-C 30 Alkyl group.

[0034] The carboxamide (f) of formula (V) is particularly preferred.

[0035]

[0036] Where n = 4-10, preferably 5-7.

[0037] Component (g): In another preferred embodiment of the invention, the additive mixture comprises at least one thiophosphate ester (g).

[0038] In the context of this invention, the thiophosphates (g) that can be used are neutral, covalently bonded thiophosphates and ionic thiophosphates, such as amine-neutralized thiophosphate derivatives.

[0039] Preferred formula (VI) thiophosphate (g)

[0040]

[0041] In another preferred embodiment of the invention, the additive mixture comprises an antiemulsifier selected from the group consisting of polyethylene glycols and / or an antifoaming agent selected from the group consisting of polyacrylates.

[0042] The preferred antiemulsifier is a block copolymer of polypropylene glycol and polyethylene glycol.

[0043] The polyacrylate preferred as a defoamer is preferably a homopolymer or copolymer of an acrylic acid derivative, such as methacrylic acid. The comonomer used is preferably a nonpolar olefin.

[0044] As an additional component of the additive mixture, dispersants, detergents, or flow-improving additives may also be used.

[0045] The additive mixture according to the invention preferably comprises components (a) to (e) in the following proportions:

[0046] At least one alkyl-substituted N-α-naphthyl-N-aniline (a) comprising 30%-90% by weight, preferably 35%-90% by weight, and particularly preferably 50%-70% by weight.

[0047] 0.1%-40% by weight, preferably 5%-30% by weight, of at least one alkyl-substituted diphenylamine (b),

[0048] At least one sulfur-containing compound (c) comprising 0.5%-10% by weight, preferably 2.5%-9% by weight,

[0049] At least one benzotriazole (d) by weight, preferably 4%-9% by weight, and

[0050] At least one oil (e) comprising 0%-30% by weight, preferably 15%-25% by weight,

[0051] The sum of components (a) to (e) is 100% by weight.

[0052] In another preferred embodiment of the invention, the additive mixture according to the invention comprises components (a) to (g) in the following proportions:

[0053] At least one alkyl-substituted N-α-naphthyl-N-aniline (a) comprising 30%-85% by weight, preferably 45%-60% by weight,

[0054] 0.1%-30% by weight, preferably 5%-20% by weight, of at least one alkyl-substituted diphenylamine (b),

[0055] At least one sulfur-containing compound (c) comprising 0.5%-5% by weight, preferably 2.5%-4% by weight.

[0056] At least one benzotriazole (d) at 0.5%-8% by weight, preferably 4%-6% by weight,

[0057] At least one oil (e) comprising 0%-30% by weight, preferably 15%-25% by weight,

[0058] At least one anti-corrosion additive, preferably carboxylamide (f), at 5%-15% by weight, preferably 7%-10% by weight.

[0059] At least one thiophosphate ester (g) comprising 0%-5% by weight, preferably 1.5%-3.5% by weight.

[0060] The sum of components (a) to (g) is 100% by weight.

[0061] The present invention further provides a method for producing an additive mixture according to the invention, wherein components (a) to (d) and optionally (e) to (g) are mixed in any desired order at a temperature of 20°C to 100°C, preferably 60°C to 80°C. They are preferably stirred until a homogeneous liquid is obtained.

[0062] The standard mixing unit can be used as a stirrer.

[0063] The present invention also provides a turbine oil comprising, preferably, a mixture of additives according to the invention in a base oil at a weight of 0.1% to 2%.

[0064] According to the American Petroleum Institute (API) classification, all oils in the five major categories can be used as base oils. Preferred are API Group III mineral oils, which have a viscosity of 32 or 46 cSt at 40°C (ISO viscosity grade 32 or 46).

[0065] The present invention further provides a method for producing turbine oil according to the invention, wherein an additive mixture having components (a) to (d) and optionally (e) to (g) according to the invention is stirred into a base oil at a temperature between 20°C and 100°C, preferably 40°C to 80°C.

[0066] The standard mixing unit can be used as a stirrer.

[0067] The present invention further provides the use of the additive mixture according to the invention, preferably in a base oil as a turbine oil.

[0068] The method according to the invention is illustrated based on the following examples, but is not limited thereto.

[0069] Example

[0070] Production of additive mixtures:

[0071] At 70°C, compounds (a) to (f) specified in Table 1 were mixed together in the amounts (by weight %) shown therein until a homogeneous solution was obtained. The mixtures from Examples B to D were liquids. The mixture from Example A (a comparative example according to EP-A 1730101) was a solid and therefore could not be used in oil without prior melting.

[0072] Turbine oil production:

[0073] The previously produced additive mixture was stirred into Yubase at 70°C in the amounts (by weight %) shown in Table 1. Yubase is a commercially available API Group III mineral base oil from SK Lubricants Co.

[0074] Table 1:

[0075]

[0076]

[0077] V = Comparative Example; RPVOT = Rotating Pressure Vessel Oxidation Test;

[0078] A mixture of N,N-bis(2-ethylhexyl)-methyl-1H-benzotriazole-1-methylamine (with the methyl group at the 4, 5, or 6 position) and N,N-bis(2-ethylhexyl)-methyl-2H-benzotriazole-1-methylamine (with the methyl group at the 4 or 5 position) in a ratio of 68% (1H) by weight to 32% (2H) by weight.

[0079] If the weight change of one of the metals (Al, Fe, Cu, Mg, or Cd) is greater than 0.25 mg / cm³ 2 If the RPVOT time after 1000 hours is still at least 25% of the original RPVOT time, and the sludge concentration after 1000 hours is less than 100 mg / kg, then it is specifically classified as passing according to ASTM D 7873. The following standard tests were performed:

[0080] Dry TOST, according to ASTM D 7873, is a standard test method used to determine the oxidative stability and insoluble substance formation of water-free turbine oils at 120°C (dry TOST method), as well as oxidation testing according to ASTM D 4636.

[0081] It has now been unexpectedly discovered that the mixture of components (a) to (d) according to the invention, see Example B, passed the oxidation test of turbine oil according to ASTM D 4636 and the dry TOST test according to ASTM D 7873, and has good solubility in oil.

[0082] It is clear from the comparative examples that these tests cannot be completed if one of the components of the mixture according to the invention is missing, or if short-chain (C8) APAN is used as component (a), the mixture cannot be stirred into the oil without pretreatment.

Claims

1. An additive mixture comprising: (a) One or more alkyl-substituted N-α-naphthyl-N-aniline of formula (I) (I) Where R1 = C 10 -C 14 alkyl, (b) One or more alkyl-substituted diphenylamines of formula (II) (II) Wherein R2 to R5 are independently equal to H or C4-C9 alkyl, provided that at least one of R2 to R5 is a C8 or C9 alkyl group. (c) at least one sulfur-containing compound of formula (III) (III) Where R = C8-C 12 alkyl, (d) At least one benzotriazole of formula (IV) (IV) Optional oil (e), and At least one corrosion inhibitor, The at least one corrosion inhibitor is a carboxamide (f) of formula (V). (V) Where n = 4-10.

2. The additive mixture according to claim 1, characterized in that, The additive mixture comprises at least one thiophosphate (g) of formula (VI). (WE).

3. The additive mixture according to any one of claims 1 to 2, characterized in that, The additive mixture contains an antiemulsifier selected from the group consisting of polyethylene glycols and / or an antifoaming agent selected from the group consisting of polyacrylates.

4. The additive mixture according to claim 1, characterized in that, The additive mixture contains the following additives: At least one alkyl-substituted N-α-naphthyl-N-aniline (a) by weight, comprising 30%-85% by weight. At least one alkyl-substituted diphenylamine (b) by weight, comprising 0.1% to 30% of the total amount. At least one sulfur-containing compound (c) at 0.5%-5% by weight, At least one benzotriazole (d) by weight, at 0.5%-8%. At least one oil (e) by weight, comprising 0%-30% At least one carboxylamide (f) by weight, comprising 5%-15% of the total weight. At least one thiophosphate ester (g) at 0%-5% by weight, The sum of components (a) to (g) is 100% by weight, and the thiophosphate (g) is represented by the following formula (VI): (WE).

5. Turbine oil, comprising an additive mixture according to any one of claims 1 to 4 in at least one base oil.

6. The turbine oil according to claim 5, characterized in that, Based on the total mixture, the additive mixture accounts for 0.1%-2% of the base oil by weight.

7. Use of the additive mixture according to any one of claims 1 to 4 in turbine oil.

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