Lubricating grease composition and preparation method thereof

Abstract

The invention provides a lubricating grease composition and a preparation method thereof, and the lubricating grease composition comprises the following raw materials by mass: 70.0-85.0% of base oil; 8.0 to 15.0% of a thickening agent; 0.2%-1.0% of an antioxidant; 1.0 to 3.0% of an antirust agent; 0.3 to 1.5 percent of an anti-wear reagent at extreme pressure; 0.5-4% of a viscosity index improver; 1-5% of a colloid stability improver; 1-5% of polytrifluorochloroethylene powder with the particle size of 0.1-1 micron; the silicone oil accounts for 30-100% of the base oil. According to the lubricating grease composition, the base oil containing the silicone oil is adopted to act together with the polytrifluorochloroethylene powder and other components, so that the lubricating grease composition has excellent low-temperature fluidity at-73 DEG C, and the low-temperature pumping performance of the lubricating grease is ensured.

Description

Technical Field

[0001] The present invention belongs to the technical field of lubricating greases, and in particular relates to a lubricating grease composition and a preparation method thereof. Background Art

[0002] Low-temperature greases are widely used in industries such as aerospace, oil and gas, automotive, energy, polar exploration, cold chain logistics, national defense, electronic instruments, and transportation to ensure the reliability and longevity of equipment in extremely cold environments. Greases are crucial to the efficiency and service life of mechanical equipment in cold climates. However, existing greases have insufficient low-temperature fluidity in ultra-low temperature environments (-73°C), resulting in reduced lubrication performance and inability to pump, rendering many devices unusable. No relevant patents or papers have been found to conduct research on the fluidity of greases in ultra-low temperature environments.

[0003] Currently, the lowest operating temperature of low-temperature greases on the market is usually above -60°C, and few products can meet the low-temperature use requirements of -73°C. Existing greases usually use low-viscosity synthetic oils (PAO, ester oils) to improve low-temperature performance. However, PAO and ester oils have very poor fluidity in a -73°C environment, resulting in poor fluidity of greases prepared with such PAO and ester oils, making them impossible to pump. In addition, the starting or operating torque is high, and similar viscosities are often difficult to pass. Summary of the Invention

[0004] In view of this, an object of the present invention is to provide a grease composition and a preparation method thereof, wherein the grease composition has excellent low-temperature fluidity at -73°C.

[0005] The present invention provides a grease composition comprising the following raw materials, calculated by mass fraction:

[0006] Base oil 70.0-85.0%; thickener 8.0-15.0%; antioxidant 0.2-1.0%; rust inhibitor 1.0-3.0%; extreme pressure anti-wear agent 0.3-1.5%; viscosity index improver 0.5-4%; colloid stability improver 1-5%; polychlorotrifluoroethylene powder (PCTFE) with a particle size of 0.1-1 micron 1-5%;

[0007] The silicone oil accounts for 30 to 100% of the base oil.

[0008] Preferably, the base oil further comprises poly-α-olefin and / or ester oil.

[0009] Preferably, the poly α-olefin is selected from one or more of PAO2, PAO3.5 and PAO4;

[0010] The ester oil is selected from one or more of trimethylolpropane ester, diisooctyl sebacate and pentaerythritol ester.

[0011] Preferably, the base oil comprises poly-α-olefin, ester oil and silicone oil in a mass ratio of (15-40):(15-30):(30-100).

[0012] Preferably, the kinematic viscosity of the base oil at 100°C is 2 to 25 mm 2 / s.

[0013] Preferably, the colloid stability improver is selected from one or more of silicon dioxide, talc, calcium carbonate and calcium phosphate;

[0014] The viscosity index improver is selected from polyisobutylene and / or polymethacrylate.

[0015] Preferably, the thickener is selected from lithium lauryl stearate soap;

[0016] The antioxidant includes a primary antioxidant and a secondary antioxidant; the primary antioxidant is an amine antioxidant; the secondary antioxidant is selected from zinc dialkyl dithiophosphate and / or dialkyl dithiocarbamate;

[0017] The rust inhibitor is selected from one or more of sulfonate rust inhibitors, carboxylic acids and carboxylate rust inhibitors;

[0018] The extreme pressure anti-wear agent is selected from one or more of nano calcium carbonate, nano zinc oxide, triphenyl phosphate, nano silicon dioxide, GMO, T361A, T203, T204, T304 and T306.

[0019] Preferably, the grease composition has a starting torque of ≤300 mN·m and a running torque of ≤50 mN·m at -73°C, and a similar viscosity of less than or equal to 900 Pa·s.

[0020] The present invention provides a method for preparing the grease composition described in the above technical solution, comprising the following steps:

[0021] The base oil, thickener and antioxidant accounting for 50-90% are mixed evenly and then melted, kept warm, and then the remaining base oil is added, cooled, kept warm again, and after cooling again, an extreme pressure anti-wear agent, a rust inhibitor, a viscosity index improver, a colloid stability improver and polytrifluorochloroethylene powder with a particle size of 0.1 to 1 micron are added, and the mixture is fully stirred and ground to obtain a grease composition.

[0022] Preferably, the melting temperature is 210-225°C and the holding time is 2-10 minutes;

[0023] Cool down to 165-190℃ and keep warm again for 20-60min;

[0024] Cool down again to 40-80℃.

[0025] The present invention provides a lubricating grease composition comprising the following ingredients, calculated by mass: 70.0-85.0% base oil; 8.0-15.0% thickener; 0.2-1.0% antioxidant; 1.0-3.0% rust inhibitor; 0.3-1.5% extreme pressure and anti-wear agent; 0.5-4% viscosity index improver; 1-5% colloidal stability improver; 1-5% polytrifluoroethylene (PTFE) powder with a particle size of 0.1-1 micron; and 30-100% silicone oil in the base oil. By utilizing a base oil containing silicone oil, in conjunction with the polytrifluoroethylene (PTFE) powder with a particle size of 0.1-1 micron, the lubricating grease composition exhibits excellent low-temperature fluidity at -73°C, ensuring low-temperature pumpability of the grease. DETAILED DESCRIPTION

[0026] The present invention provides a grease composition comprising the following raw materials, calculated by mass fraction:

[0027] Base oil 70.0-85.0%; thickener 8.0-15.0%; antioxidant 0.2-1.0%; rust inhibitor 1.0-3.0%; extreme pressure and anti-wear agent 0.3-1.5%; viscosity index improver 0.5-4%; colloid stability improver 1-5%; polytrifluorochloroethylene powder with a particle size of 0.1-1 micron 1-5%;

[0028] The silicone oil accounts for 30 to 100% of the base oil.

[0029] The present invention adopts a base oil containing silicone oil and a polytrifluorochloroethylene powder with a particle size of 0.1 to 1 micron to make the grease composition have excellent low-temperature fluidity, thereby ensuring the low-temperature pumping performance of the grease.

[0030] The grease composition provided by the present invention comprises 70.0% to 85.0% of a base oil; the amount used can be specifically 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%, 83%, 84% or 85%. The silicone oil accounts for 30% to 100% by weight of the base oil. The kinematic viscosity of the base oil at 100°C is 2 to 25 mm 2 / s.

[0031] The base oil in the present invention preferably further comprises polyα-olefin and / or ester oil; the polyα-olefin is selected from one or more of PAO2, PAO3.5 and PAO4; the ester oil is selected from one or more of trimethylolpropane ester, diester and pentaerythritol ester.

[0032] The base oil in the present invention preferably comprises polyalphaolefin, ester oil and silicone oil in a mass ratio of (15-40): (15-30): (30-100), preferably (15-25): (15-25): (35-50). The ester oil is selected from trimethylolpropane ester, pentaerythritol ester or diisooctyl sebacate. In a specific embodiment, the base oil is silicone oil with a kinematic viscosity of 4.65 mm at 100°C. 2 / s; or the base oil comprises 25:15:40 poly α-olefin PAO3.5, diisooctyl sebacate oil and silicone oil, the base oil kinematic viscosity at 100 ° C is 3.94mm 2 / s; or the base oil comprises 20:25:35 poly α-olefin PAO2, pentaerythritol ester oil and silicone oil, the base oil at 100 ° C kinematic viscosity of 3.84mm 2 / s.

[0033] The raw materials for preparing the grease composition provided by the present invention include 8.0-15.0% of a thickener, and the amount used can be 8.0%, 8.5%, 9.0%, 9.5%, 10.0%, 10.5%, 11%, 11.5%, 12%, 12.5%, 13%, 13.5%, 14%, 14.5% or 15.0%. The thickener is lithium dodecyl stearate soap.

[0034] The raw materials for preparing the grease composition provided by the present invention include 0.2-1.0% antioxidant, specifically used in an amount of 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, or 1.0%. The antioxidant includes a primary antioxidant and a secondary antioxidant; the primary antioxidant is an amine antioxidant selected from one or more of L57, V81, and L06; and the secondary antioxidant is selected from zinc dialkyl dithiophosphate and / or dialkyl dithiocarbamate.

[0035] The raw materials for preparing the grease composition provided by the present invention include 1.0-3.0% of a rust inhibitor, specifically 1.0%, 1.2%, 1.4%, 1.6%, 1.8%, 2.0%, 2.2%, 2.4%, 2.6%, 2.8%, or 3.0%. The rust inhibitor is preferably selected from one or more of sulfonate rust inhibitors, carboxylic acids, and carboxylate rust inhibitors; more preferably, one or more of calcium petroleum sulfonate, barium petroleum sulfonate, barium dinonylnaphthalene sulfonate, dodecenylsuccinic acid, dodecenylbutanediol, zinc naphthenate, and lanolin magnesium soap.

[0036] The grease composition provided by the present invention comprises 0.3-1.5% of an extreme pressure anti-wear agent in a specific amount of 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, or 1.5%. The extreme pressure anti-wear agent is selected from one or more of nano-calcium carbonate, nano-zinc oxide, triphenyl phosphate, nano-silicon dioxide, GMO, T361A, T203, T204, T304, and T306. Nano-calcium carbonate, nano-zinc oxide, triphenyl phosphate, and nano-silicon dioxide are all solid lubricants, while GMO, T361A, T203, T204, T304, and T306 are all liquid lubricants.

[0037] The grease composition provided by the present invention comprises 0.5-4% of a viscosity index improver, wherein the amount used is specifically 0.5%, 0.6%, 0.7%, 0.8%, 0.9%, 1.0%, 1.1%, 1.2%, 1.3%, 1.4%, 1.5%, 1.6%, 1.7%, 1.8%, 1.9%, 2.0%, 2.1%, 2.2%, 2.3%, 2.4%, 2.5%, 2.6%, 2.7%, 2.8%, 2.9%, 3.0%, 3.1%, 3.2%, 3.3%, 3.4%, 3.5%, 3.6%, 3.7%, 3.8%, 3.9% or 4.0%. The viscosity index improver is selected from polyisobutylene and / or polymethacrylate.

[0038] The grease composition provided by the present invention comprises 1-5% of a colloid stability improver in a specific amount of 1.0%, 1.2%, 1.4%, 1.6%, 1.8%, 2.0%, 2.2%, 2.4%, 2.6%, 2.8%, 3.0%, 3.2%, 3.4%, 3.6%, 3.8%, 4.0%, 4.2%, 4.4%, 4.6%, 4.8%, or 5.0%. The colloid stability improver is selected from one or more of silicon dioxide, talc, calcium carbonate, and calcium phosphate. These colloid stability improvers can reduce oil separation and enhance the colloid stability of the product.

[0039] The grease composition provided by the present invention comprises 1-5% polychlorotrifluoroethylene powder with a particle size of 0.1-1 micron, with specific amounts being 1%, 1.2%, 1.4%, 1.6%, 1.8%, 2.0%, 2.2%, 2.4%, 2.6%, 2.8%, 3.0%, 3.2%, 3.4%, 3.6%, 3.8%, 4.0%, 4.2%, 4.4%, 4.6%, 4.8%, or 5.0%. The polychlorotrifluoroethylene powder with a particle size of 0.1-1 micron acts as a fluidity improver, working in conjunction with silicone oil to impart excellent low-temperature fluidity to the grease composition at -73°C, ensuring low-temperature pumpability. In specific embodiments, the polychlorotrifluoroethylene powder is PCTFE powder with an average particle size of 0.1 micron, PCTFE powder with a particle size of 0.3 micron, or PCTFE powder with a particle size of 1 micron.

[0040] The grease composition provided by the present invention has a starting torque of ≤200 mN·m, a running torque of ≤50 mN·m, and an approximate viscosity of 900 Pa·s or less at -73°C. In specific embodiments, the approximate viscosity of the grease composition at -73°C is 623 Pa·s, 845 Pa·s, or 489 Pa·s; the starting torque is 80 to 157 mN·m, and the running torque is 20 to 46 mN·m.

[0041] In a specific embodiment of the present invention, the grease composition comprises the following raw materials by mass fraction:

[0042] 76% silicone oil; 15% lithium soap of dodecyl stearate; 0.5% amine antioxidant L57; 0.3% secondary antioxidant zinc dialkyl dithiophosphate; 1.6% barium dinonylnaphthalenesulfonate; 1.0% nano-calcium carbonate and 0.5% T203; 1.5% polymethacrylate; 1.8% talc and 1.8% PCTFE powder with an average particle size of 0.1 micron.

[0043] In a specific embodiment of the present invention, the grease composition comprises the following raw materials, calculated by mass: 25% polyalphaolefin (PAO3.5), 15% diethyl hexyl sebacate, 40% silicone oil; 10% lithium dodecyl stearate soap; 0.5% amine antioxidant V81 and 0.3% secondary antioxidant zinc dialkyl dithiophosphate; 1.5% barium petroleum sulfonate and 0.5% zinc cyclohexane; 1.0% nano-silica and 0.2% T203; 1.0% silica; 2% polyisobutylene; and 3.0% PCTFE powder with an average particle size of 0.3 microns.

[0044] In another specific embodiment of the present invention, the grease composition comprises the following raw materials, calculated by mass: 20% polyalphaolefin (PAO2), 25% ester oil (pentaerythritol ester) and 35% silicone oil; 8.0% lithium dodecyl stearate soap; 0.4% amine antioxidant V81 and 0.2% dialkyl dithioformate; 2% barium petroleum sulfonate and 0.5% dodecenyl butyric acid; 1.0% T361A and 0.4% T204; 1% polymethacrylate; 1% polyisobutylene; 1.0% calcium carbonate and 4.5% PCTFE powder with an average particle size of 1 micron.

[0045] The present invention provides a method for preparing the grease composition described in the above technical solution, comprising the following steps:

[0046] The base oil, thickener and antioxidant accounting for 50-90% are mixed evenly and then melted, kept warm, and the remaining base oil is added, cooled, and kept warm again. After cooling again, extreme pressure anti-wear agent, rust inhibitor, viscosity index improver, colloid stability improver and PCTFE powder are added, and the mixture is fully stirred and ground to obtain a grease composition.

[0047] The types of raw materials used in the preparation method provided by the present invention are the same as those described in the above technical solution and will not be repeated here.

[0048] In order to improve the colloidal stability of grease, a specific type of colloidal stability improver is used to reduce the oil separation rate, and by optimizing the preparation process and reasonably controlling the cooling method and holding time, the colloidal stability of the product is further enhanced.

[0049] In the present invention, the melting temperature is 210-225°C, and the holding time is 2-10 min; the temperature is lowered to 165-190°C, specifically 165°C, 170°C, 175°C, 180°C, 185°C or 190°C; the holding time again is 20-60 min, specifically 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min or 60 min. The second holding treatment makes the grease composition have a lower pressure oil separation, indicating that its colloid stability is excellent; in the present invention, the temperature is lowered again to 40-80°C, specifically 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C or 80°C.

[0050] The present invention preferably adopts a three-roll mill for grinding; grinding is carried out at least three times.

[0051] In order to further illustrate the present invention, a grease composition and a preparation method thereof provided by the present invention are described in detail below with reference to examples, but they should not be construed as limiting the scope of protection of the present invention.

[0052] Example 1

[0053] Base oil: 76% silicone oil, kinematic viscosity at 100°C is 4.65mm 2 / s;

[0054] Thickener: 15% lithium lauryl stearate soap;

[0055] Antioxidant: 0.5% amine antioxidant L57 and 0.3% secondary antioxidant zinc dialkyl dithiophosphate are mixed and used;

[0056] Rust inhibitor: 1.6% barium dinonylnaphthalenesulfonate;

[0057] Extreme pressure and anti-wear agent: 1.0% nano calcium carbonate and 0.5% T203;

[0058] Viscosity index improver: 1.5% polymethacrylate;

[0059] Colloid stability improver: 1.8% talc;

[0060] Flow improver: 1.8% PCTFE powder with an average particle size of 0.1 micron.

[0061] Preparation method:

[0062] Step (1) The first portion of base oil, which accounts for 70% of the total weight of the base oil, is added into the reactor.

[0063] Step (2) adding lithium dodecyl stearate soap into the reactor according to the formula ratio.

[0064] In step (3), the antioxidant is also added into the reactor according to the formula ratio.

[0065] Step (4) Start stirring to fully mix the base oil and thickener.

[0066] Step (5) The temperature was raised to 220°C for melting and kept at this temperature for 5 minutes.

[0067] After the insulation in step (6) is completed, the remaining 30% of the base oil is added to the reactor.

[0068] In step (7), when the temperature drops to 170° C., the heat preservation treatment is started, and the heat preservation time is controlled at 30 minutes.

[0069] After the insulation in step (8) is completed, when the temperature is lowered to 50° C., an extreme pressure anti-wear agent, a rust inhibitor, a viscosity index improver, a colloid stability improver and PCTFE powder are added and stirred thoroughly.

[0070] After the stirring in step (9) is completed, the mixture is ground three times using a three-roll grinder to obtain the finished product.

[0071] Example 2

[0072] Base oil: 25% polyalphaolefin (PAO3.5), 15% dioctyl sebacate and 40% silicone oil. The kinematic viscosity of the base oil at 100°C is 3.94 mm 2 / s;

[0073] Thickener: 10% lithium lauryl stearate soap;

[0074] Antioxidant: 0.5% amine antioxidant V81 and 0.3% secondary antioxidant zinc dialkyl dithiophosphate are mixed and used;

[0075] Rust inhibitor: 1.5% barium petroleum sulfonate and 0.5% zinc naphthenate;

[0076] Extreme pressure and anti-wear agent: 1.0% nano-silica and 0.2% T203;

[0077] Colloidal stability improver: 1.0% silicon dioxide;

[0078] Viscosity index improver: 2% polyisobutylene;

[0079] Flow improver: 3.0% PCTFE powder with an average particle size of 0.3 microns.

[0080] Preparation method:

[0081] Step (1) The first portion of base oil, which accounts for 70% of the total weight of the base oil, is added into the reactor.

[0082] Step (2) adding lithium dodecyl stearate soap into the reactor according to the formula ratio.

[0083] In step (3), the antioxidant is also added into the reactor according to the formula ratio.

[0084] Step (4) Start stirring to fully mix the base oil and thickener.

[0085] Step (5) The temperature was raised to 220°C for melting and kept at this temperature for 4 minutes.

[0086] After the insulation in step (6) is completed, the remaining 30% of the base oil is added to the reactor.

[0087] In step (7), when the temperature drops to 170° C., the heat preservation treatment is started, and the heat preservation time is controlled at 50 minutes.

[0088] After the insulation in step (8) is completed, when the temperature is lowered to 50° C., an extreme pressure anti-wear agent, a rust inhibitor, a viscosity index improver, a colloid stability improver and PCTFE powder are added and stirred thoroughly.

[0089] After the stirring in step (9) is completed, the mixture is ground three times using a three-roll grinder to obtain the finished product.

[0090] Example 3

[0091] Base oil: 20% polyalphaolefin (PAO2), 25% ester oil (pentaerythritol ester) and 35% silicone oil. The kinematic viscosity of the base oil at 100°C is 3.84 mm 2 / s;

[0092] Thickener: 8.0% lithium lauryl stearate soap;

[0093] Antioxidants: 0.4% amine antioxidant V81 and 0.2% dialkyl dithioformate;

[0094] Rust inhibitor: a mixture of 2% barium petroleum sulfonate and 0.5% dodecenyl butyric acid;

[0095] Extreme pressure anti-wear agent: 1.0% T361A and 0.4% T204;

[0096] Viscosity index improver: 1% polymethacrylate and 1% polyisobutylene;

[0097] Colloid stability improver: 1.0% calcium carbonate;

[0098] Flow improver: 4.5% PCTFE powder with an average particle size of 1 micron.

[0099] Preparation method:

[0100] Step (1) The first portion of base oil, which accounts for 80% of the total weight of the base oil, is added into the reactor.

[0101] In step (2), lithium dodecyl stearate soap is also added into the reactor according to the formula ratio.

[0102] In step (3), the antioxidant is also added into the reactor according to the formula ratio.

[0103] Step (4) Start stirring to fully mix the base oil and thickener.

[0104] Step (5) The temperature was raised to 220°C for melting and kept at this temperature for 8 minutes.

[0105] After the insulation in step (6) is completed, the remaining 20% ​​of the base oil is added to the reactor.

[0106] In step (7), when the temperature drops by 160° C., the heat preservation treatment is started, and the heat preservation time is controlled at 40 minutes.

[0107] After the insulation in step (8) is completed, when the temperature is lowered to 50° C., an extreme pressure anti-wear agent, a rust inhibitor, a viscosity index improver, a colloid stability improver and PCTFE powder are added and stirred thoroughly.

[0108] After the stirring in step (9) is completed, the mixture is ground three times using a three-roll grinder to obtain the finished product.

[0109] Comparative Example 1

[0110] Base oil: 40% polyalphaolefin (PAO3.5) and 40% dioctyl sebacate, the base oil has a kinematic viscosity of 3.30 mm at 100°C. 2 / s;

[0111] Thickener: 10% lithium lauryl stearate soap;

[0112] Antioxidant: 0.5% amine antioxidant V81 and 0.3% secondary antioxidant zinc dialkyl dithiophosphate are mixed and used;

[0113] Rust inhibitor: 1.5% barium petroleum sulfonate and 0.5% zinc naphthenate;

[0114] Extreme pressure and anti-wear agent: 1.0% nano-silica and 0.2% T203;

[0115] Colloidal stability improver: 1.0% silicon dioxide;

[0116] Viscosity index improver: 2% polyisobutylene;

[0117] Flow improver: 3.0% PCTFE powder with an average particle size of 0.3 microns.

[0118] Preparation method:

[0119] Step (1) The first portion of base oil, which accounts for 70% of the total weight of the base oil, is added into the reactor.

[0120] Step (2) adding lithium dodecyl stearate soap into the reactor according to the formula ratio.

[0121] In step (3), the antioxidant is also added into the reactor according to the formula ratio.

[0122] Step (4) Start stirring to fully mix the base oil and thickener.

[0123] Step (5) The temperature was raised to 220°C for melting and kept at this temperature for 4 minutes.

[0124] After the insulation in step (6) is completed, the remaining 30% of the base oil is added to the reactor.

[0125] In step (7), when the temperature drops to 170° C., the heat preservation treatment is started, and the heat preservation time is controlled at 50 minutes.

[0126] After the insulation in step (8) is completed, when the temperature is lowered to 50° C., an extreme pressure anti-wear agent, a rust inhibitor, a viscosity index improver, a colloid stability improver and PCTFE powder are added and stirred thoroughly.

[0127] After the stirring in step (9) is completed, the mixture is ground three times using a three-roll grinder to obtain the finished product.

[0128] Comparative Example 2

[0129] Base oil: 27% polyalphaolefin (PAO3.5), 16% diisooctyl sebacate and 40% silicone oil. The kinematic viscosity of the base oil at 100°C is 3.92 mm 2 / s;

[0130] Thickener: 10% lithium lauryl stearate soap;

[0131] Antioxidant: 0.5% amine antioxidant V81 and 0.3% secondary antioxidant zinc dialkyl dithiophosphate are mixed and used;

[0132] Rust inhibitor: 1.5% barium petroleum sulfonate and 0.5% zinc naphthenate;

[0133] Extreme pressure and anti-wear agent: 1.0% nano-silica and 0.2% T203;

[0134] Colloidal stability improver: 1.0% silicon dioxide;

[0135] Viscosity index improver: 2% polyisobutylene;

[0136] Preparation method:

[0137] Step (1) The first portion of base oil, which accounts for 70% of the total weight of the base oil, is added into the reactor.

[0138] Step (2) adding lithium dodecyl stearate soap into the reactor according to the formula ratio.

[0139] In step (3), the antioxidant is also added into the reactor according to the formula ratio.

[0140] Step (4) Start stirring to fully mix the base oil and thickener.

[0141] Step (5) The temperature was raised to 220°C for melting and kept at this temperature for 4 minutes.

[0142] After the insulation in step (6) is completed, the remaining 30% of the base oil is added to the reactor.

[0143] In step (7), when the temperature drops to 170° C., the heat preservation treatment is started, and the heat preservation time is controlled at 50 minutes.

[0144] After the insulation in step (8) is completed, the extreme pressure anti-wear agent, rust inhibitor, viscosity index improver and colloid stability improver are added when the temperature is lowered to 50°C and the mixture is fully stirred.

[0145] After the stirring in step (9) is completed, the mixture is ground three times using a three-roll grinder to obtain the finished product.

[0146] Comparative Example 3

[0147] Based on Example 3, the heat preservation step was not performed.

[0148] Base oil: 20% polyalphaolefin (PAO2), 25% ester oil (pentaerythritol ester) and 35% silicone oil. The kinematic viscosity of the base oil at 100°C is 3.84 mm 2 / s;

[0149] Thickener: 8.0% lithium lauryl stearate soap;

[0150] Antioxidants: 0.4% amine antioxidant V81 and 0.2% dialkyl dithioformate;

[0151] Rust inhibitor: a mixture of 2% barium petroleum sulfonate and 0.5% dodecenyl butyric acid;

[0152] Extreme pressure anti-wear agent: 1.0% T361A and 0.4% T204;

[0153] Viscosity index improver: 1% polymethacrylate and 1% polyisobutylene;

[0154] Colloid stability improver: 1.0% calcium carbonate;

[0155] Flow improver: 4.5% PCTFE powder with an average particle size of 1 micron.

[0156] Preparation method:

[0157] Step (1) The first portion of base oil, which accounts for 80% of the total weight of the base oil, is added into the reactor.

[0158] In step (2), lithium dodecyl stearate soap is also added into the reactor according to the formula ratio.

[0159] In step (3), the antioxidant is also added into the reactor according to the formula ratio.

[0160] Step (4) Start stirring to fully mix the base oil and thickener.

[0161] Step (5) The temperature was raised to 220°C for melting and kept at this temperature for 8 minutes.

[0162] After the insulation in step (6) is completed, the remaining 20% ​​of the base oil is added to the reactor.

[0163] In step (7), when the temperature drops to 50° C., an extreme pressure anti-wear agent, a rust inhibitor, a viscosity index improver, a colloid stability improver and PCTFE powder are added and stirred thoroughly.

[0164] After the stirring in step (8) is completed, the mixture is ground three times using a three-roll grinder to obtain the finished product.

[0165] The present invention conducted performance tests on the finished products prepared in the above examples and comparative examples, and the results are shown in Table 1:

[0166] Table 1

[0167]

[0168]

[0169] The present invention conducted a performance test on the finished product prepared in the above comparative example, and the results are shown in Table 2:

[0170] Table 2

[0171]

[0172] As can be seen from the above examples, the present invention provides a grease composition comprising the following ingredients, by mass: 70.0-85.0% base oil; 8.0-15.0% thickener; 0.2-1.0% antioxidant; 1.0-3.0% rust inhibitor; 0.3-1.5% extreme pressure and anti-wear agent; 0.5-4% viscosity index improver; 1-5% colloidal stability improver; 1-5% polytrifluoroethylene (PTFE) powder with a particle size of 0.1-1 micron; and 30-100% silicone oil in the base oil. By utilizing a base oil containing silicone oil, in conjunction with the PTFE powder with a particle size of 0.1-1 micron, the present invention provides the grease composition with excellent low-temperature fluidity at -73°C, ensuring low-temperature pumpability of the grease.

[0173] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A grease composition comprising the following raw materials, calculated by mass fraction: Base oil 70.0-85.0%; thickener 8.0-15.0%; antioxidant 0.2-1.0%; rust inhibitor 1.0-3.0%; extreme pressure and anti-wear agent 0.3-1.5%; viscosity index improver 0.5-4%; colloid stability improver 1-5%; polytrifluorochloroethylene powder with a particle size of 0.1-1 micron 1-5%; The silicone oil accounts for 30 to 100% of the base oil.

2. The grease composition according to claim 1, wherein The base oil also includes poly-α-olefin and / or ester oil.

3. The grease composition according to claim 2, characterized in that The poly α-olefin is selected from one or more of PAO2, PAO3.5 and PAO4; The ester oil is selected from one or more of trimethylolpropane ester, diisooctyl sebacate and pentaerythritol ester.

4. The grease composition according to claim 2, wherein The base oil comprises polyalphaolefin, ester oil and silicone oil in a mass ratio of (15-40):(15-30):(30-100).

5. The grease composition according to claim 1, wherein The kinematic viscosity of the base oil at 100°C is 2 to 25 mm 2 / s.

6. The grease composition according to claim 1, wherein The colloidal stability improver is selected from one or more of silicon dioxide, talc, calcium carbonate and calcium phosphate; The viscosity index improver is selected from polyisobutylene and / or polymethacrylate.

7. The grease composition according to claim 1, wherein The thickener is selected from lithium lauryl stearate soap; The antioxidant includes a primary antioxidant and a secondary antioxidant; the primary antioxidant is an amine antioxidant; the secondary antioxidant is selected from zinc dialkyl dithiophosphate and / or dialkyl dithiocarbamate; The rust inhibitor is selected from one or more of sulfonate rust inhibitors, carboxylic acids and carboxylate rust inhibitors; The extreme pressure anti-wear agent is selected from one or more of nano calcium carbonate, nano zinc oxide, triphenyl phosphate, nano silicon dioxide, GMO, T361A, T203, T204, T304 and T306.

8. The grease composition according to claim 1, wherein The grease composition has a starting torque of ≤200 mN·m, an operating torque of ≤50 mN·m at -73°C, and a similar viscosity of less than or equal to 900 Pa·s.

9. A method for preparing the grease composition according to claim 1, comprising the following steps: The base oil, thickener and antioxidant accounting for 50-90% are mixed evenly and then melted, kept warm, and then the remaining base oil is added, cooled, kept warm again, and after cooling again, an extreme pressure anti-wear agent, a rust inhibitor, a viscosity index improver, a colloid stability improver and polytrifluorochloroethylene powder with a particle size of 0.1 to 1 micron are added, and the mixture is fully stirred and ground to obtain a grease composition.

10. The preparation method according to claim 9, characterized in that The melting temperature is 210-225°C and the holding time is 2-10 minutes; Cool down to 165-190℃ and keep warm again for 20-60min; Cool down again to 40-80℃.

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