A long-life low-friction grease composition and a preparation method thereof

Abstract

This application relates to the technical field of greases, and specifically discloses a long-life and low-friction grease composition. The long-life and low-friction grease composition comprises the following components in parts by weight: 30-40 parts of high-base calcium sulfonate, 60-80 parts of base oil, 1-3 parts of 5,5-dimethylhydantoin, 1-3 parts of hydroxymethylurea, 0.5-2 parts of sodium carboxymethyl cellulose, 0.5-1 part of sodium stearate, 1-4 parts of a conversion agent, 1-2 parts of calcium hydroxide, C 12 -C 20 3-5 parts of hydroxy fatty acid, 1-3 parts of solid friction reducer, 1-3 parts of antioxidant, and 1-3 parts of passivator. The grease composition prepared in this application has the characteristics of long service life and excellent friction performance.

Description

Technical Field

[0001] This application relates to the technical field of greases. More specifically, it relates to a long-life and low-friction grease composition and a preparation method thereof. Background Art

[0002] Calcium sulfonate was initially mostly used as a lubricating oil detergent and rust inhibitor. However, after the 1950s, foreign researchers began to successfully prepare a grease with a much higher dropping point than that prepared from calcium fatty acid soap using calcium sulfonate as a thickener - calcium sulfonate-based grease. However, the thickening ability of oil-soluble Newtonian calcium sulfonate is relatively small, and there are many inconveniences in use. Therefore, in the 1960s and 1970s, relevant researchers discovered a method to convert calcium sulfonate from Newtonian to non-Newtonian, and introduced the overbased technology into the preparation of calcium sulfonate-based grease, which promoted the birth of overbased complex calcium sulfonate grease. However, due to the excessive viscosity and poor low-temperature pumpability of the initial complex calcium sulfonate grease, it was not widely used. In the 1980s, after adding borate and fatty acid, the performance was greatly improved, and the "new generation of high-efficiency grease" was successfully prepared.

[0003] The overbased complex calcium sulfonate grease has developed rapidly in recent years. It has received wide attention due to its excellent anti-shear performance and tribological performance under high-temperature conditions. In addition, due to its good load-carrying capacity, thermal stability and colloidal stability, it is widely used in high-temperature and heavy-load equipment. Compared with other greases, the complex calcium sulfonate grease is more suitable for use under harsh working conditions. Moreover, the complex calcium sulfonate grease does not contain heavy metals and other functional additives harmful to the environment, so it is also an environmentally friendly grease.

[0004] The thickener system of the complex calcium sulfonate grease mainly consists of two parts. One part is overbased non-Newtonian calcium sulfonate, in which calcium carbonate exists in the calcite crystal form. The other part is complex calcium soap. The two parts have both physical mixing and chemical association, which is a relatively complex compound system. The special composite structure makes its soap content higher than that of common lithium-based and polyurea-based greases. As a result, two problems have arisen. One is that the friction coefficient of the complex calcium sulfonate grease is higher than that of other types of greases. The other is that the relatively small content of base oil is likely to cause insufficient bearing lubrication, and it is not suitable for making long-life greases.

[0005] In order to improve the disadvantages and deficiencies existing in the use of the existing complex calcium sulfonate grease and expand the scope of use of the existing grease products, the demand for developing higher-performance grease products is increasing continuously. Summary of the Invention

[0006] To solve the above technical problems, the present application provides a long-life and low-friction grease composition and a preparation method thereof. The grease composition prepared by the present application has the characteristics of long service life and excellent friction performance.

[0007] In the first aspect, the present application provides a long-life and low-friction grease composition, adopting the following technical solution:

[0008] A long-life and low-friction grease composition, comprising the following components in parts by weight: 30-40 parts of overbased calcium sulfonate, 60-80 parts of base oil, 1-3 parts of 5,5-dimethylhydantoin, 1-3 parts of hydroxymethylurea, 0.5-2 parts of sodium carboxymethylcellulose, 0.5-1 part of sodium stearate, 1-4 parts of conversion agent, 1-2 parts of calcium hydroxide, C 12 -C 20 3-5 parts of hydroxy fatty acid, 1-3 parts of solid anti-friction agent, 1-3 parts of antioxidant, 1-3 parts of passivator.

[0009] Preferably, the base oil is selected from one or more of hydrogenated mineral oil, polyalphaolefin synthetic oil and naphthenic base oil.

[0010] Preferably, the base oil is polyalphaolefin synthetic oil.

[0011] Since when the grease forms an oil film on the surface of the friction pair, both the thickening system and the base oil are involved, and the base oil has a greater impact on the oil film. When the polyalphaolefin synthetic oil is used as the base oil in this system, the prepared grease has the best anti-friction performance and the lowest friction coefficient. This is because at high rotational speeds, the oil film generated on the surface of the friction pair mainly depends on the base oil, and the polyalphaolefin synthetic oil itself has good anti-friction performance. The addition of calcium hydroxide can thicken the system and introduce calcium ion complexation. The addition of 5,5-dimethylhydantoin and hydroxymethylurea can not only improve the heat resistance of the complex thickener, but also play a catalytic role in the conversion agent reaction, making the generated grease system stable and greatly extending the service life of the grease.

[0012] Preferably, the base number of the overbased calcium sulfonate is 400-450 mgKOH·g -1 , and calculated by mass fraction, the calcium content is 15-16%.

[0013] Preferably, the base number of the overbased calcium sulfonate is 410 mgKOH·g -1 . Calculated by mass fraction, the calcium content is 15.5%.

[0014] The main components of the complex thickener are overbased calcium sulfonate and complex soap. Among them, in the overbased calcium sulfonate, the higher the base number, the higher the calcium carbonate content.

[0015] Preferably, the conversion agent is a mixture composed of isopropyl alcohol and glacial acetic acid.

[0016] When preparing a high-base-number complex calcium sulfonate grease, the key to grease formation lies in converting oil-soluble raw materials into thixotropic grease, mainly relying on the crystal form transformation of amorphous calcium carbonate in the raw materials. By screening process conditions and raw materials to promote crystal form transformation to form calcite crystal form calcium carbonate, a large amount of amorphous calcium carbonate and loose vaterite crystal form structure should not be left due to improper transformation.

[0017] Since CaCO3 is a weak acid salt, it is extremely easy to react with active hydrogen substances to form soluble acid salts, and the acid salts are converted back into CaCO3 after heating. In this process, it is necessary to select a suitable conversion agent to replace CO2 in the reaction, and at the same time, the conversion agent needs to meet the requirements of being easily removed and not affecting the thickening system. Currently, long-chain fatty acids, hydroxy long-chain fatty acids, small molecule organic acids, inorganic acids, alcohols, etc. are generally added to the material to generate CO2 by itself to promote crystal form transformation.

[0018] In this application, the conversion agent is preferably a composite of isopropyl alcohol and glacial acetic acid, and under the action of other raw materials in the system, it can more completely promote the crystal form transformation of calcium carbonate.

[0019] Preferably, the thickener is selected from one of ethylene-propylene copolymers, polyisobutylene, and polymethacrylate.

[0020] Preferably, the thickener is polymethacrylate.

[0021] The addition of the thickener will affect the tribological properties of the grease because the thickener will adsorb on the surface of the fiber structure of the thickening system, making the fiber structure of the grease more compact and reducing the oil separation ability of the grease to a certain extent. Polymethacrylate has the least influence on the tribological properties of the grease because the polymethacrylate molecules adsorb less on the surface of the grease fiber structure, have less influence on the morphology of the grease, and are not likely to affect the oil separation ability of the grease.

[0022] Preferably, the solid anti-friction agent is selected from one of nano tungsten dioxide and nano molybdenum dioxide.

[0023] Preferably, the antioxidant is selected from one of diphenylamine or phenyl-α-naphthylamine.

[0024] Preferably, the passivator is selected from one of benzotriazole derivatives, thiadiazole derivatives, and heterocyclic compounds.

[0025] In a second aspect, this application provides a preparation method for a long-life and low-friction grease composition, adopting the following technical solution:

[0026] S1, mix high-base-number calcium sulfonate and base oil, stir evenly and heat up to 70 - 90 °C;

[0027] S2, Add the conversion agent and stir evenly. Heat up to 85 - 100 °C and react for 0.5 - 1 h. Then continue to add 5,5 - dimethylhydantoin and hydroxymethylurea and stir evenly. Keep the temperature for 0.5 - 1 h.

[0028] S3, Control the temperature at 90 - 100 °C, add calcium hydroxide and stir for 5 - 10 min, then add C 12 -C 20 Hydroxy fatty acid for saponification reaction, and the saponification time is 1 - 2 h.

[0029] S4, Cool down to below 90 °C, add sodium carboxymethylcellulose, sodium stearate, solid anti - friction agent, antioxidant and passivator and stir for 10 - 20 min, then homogenize and degas to obtain the finished product.

[0030] In summary, the present application has the following beneficial effects:

[0031] (1) By adding 5,5 - dimethylhydantoin and hydroxymethylurea, on the one hand, it can synergistically inhibit the oxidation reaction of the grease in high - temperature environment with the antioxidant. On the other hand, the compound of 5,5 - dimethylhydantoin and hydroxymethylurea can act as a catalyst for the crystal form transformation of amorphous calcium carbonate in over - based calcium sulfonate, completely converting the oil - soluble raw materials in the grease into thixotropy, resulting in a stable grease system and greatly extending the service life of the grease.

[0032] (2) When the grease is in the lubrication work, the lubrication protection is mainly provided by the base oil. Under the boundary friction state, the solid anti - friction agent can play a good role in compression and anti - friction. By adding sodium carboxymethylcellulose and sodium stearate in this application, the adhesion of the grease on the lubricating surface can be improved, and the lubrication effect of the grease can be enhanced. In addition, the combined action of sodium carboxymethylcellulose, sodium stearate and solid anti - friction agent can further improve the anti - friction ability and extreme pressure performance of the grease. Detailed Embodiments

[0033] The following further details the present application with reference to the embodiments.

[0034] In the following examples and comparative examples, the base oil used is polyalphaolefin, with a kinematic viscosity at 40 °C of 140 - 160 mm 2 / s, purchased from ExxonMobil; the over - based calcium sulfonate has a base number of 405 mgKOH·g -1, the calcium content is 15.5% by mass fraction, purchased from Jinzhou Kangtai Lubricant Additive Co., Ltd.; sodium hydroxymethyl cellulose is purchased from Langfang Pengcai Fine Chemical Co., Ltd.; the viscosity enhancer is polyisobutylene, purchased from Shandong Hongrui New Materials Technology Co., Ltd.; the solid anti-friction agent is nano molybdenum dioxide, with a particle size of 10-20nm; the antioxidant is N-phenyl-α-naphthylamine; the metal passivator is zinc dialkyl dithiophosphate, purchased from Jinzhou Jiaduorun Materials Technology Co., Ltd. The passivator is a benzotriazole derivative, purchased from Yantai Hengnuo New Materials Co., Ltd., model TH551; the conversion agent is a mixture of isopropanol and glacial acetic acid in a mass ratio of 1:1.

[0035] Example

[0036] Example 1

[0037] A long-life low-friction grease composition is prepared by the following steps:

[0038] S1, mix 3kg of high base calcium sulfonate and 6kg of polyalphaolefin base oil, stir evenly and heat to 70°C;

[0039] S2, add 0.1 kg of conversion agent and stir evenly, heat to 85 ° C, react for 1 hour, continue to add 0.1 kg of 5,5-dimethylhydantoin and 0.1 kg of hydroxymethyl urea and stir evenly, keep warm for 1 hour;

[0040] S3, control the temperature at 90°C, add 0.1kg calcium hydroxide and stir for 10min, add 0.3kg dodecyl hydroxystearic acid for saponification reaction, and the saponification time is 2h;

[0041] S4, cool down to below 90°C, add 0.05kg sodium hydroxymethyl cellulose, 0.05kg sodium stearate, 0.1kg nano molybdenum dioxide, 0.1kg N-phenyl-α-naphthylamine and 0.1kg passivator TH551 and stir for 20min, homogenize and degas to obtain the finished product.

[0042] Example 2

[0043] A long-life low-friction grease composition is prepared by the following steps:

[0044] S1, mix 4 kg of high base calcium sulfonate and 8 kg of polyalphaolefin base oil, stir evenly and heat to 70°C;

[0045] S2, add 0.4 kg of conversion agent and stir evenly, heat to 85 ° C, react for 1 hour, continue to add 0.3 kg of 5,5-dimethylhydantoin and 0.3 kg of hydroxymethyl urea and stir evenly, keep warm for 1 hour;

[0046] S3, control the temperature at 90 °C, add 0.2 kg of calcium hydroxide and stir for 10 min, then add 0.5 kg of dodecahydroxystearic acid for saponification reaction, and the saponification time is 2 h;

[0047] S4, cool down to below 90 °C, add 0.2 kg of sodium carboxymethyl cellulose, 0.1 kg of sodium stearate, 0.3 kg of molybdenum dioxide nanometer, 0.3 kg of N-phenyl-α-naphthylamine and 0.3 kg of passivator TH551 and stir for 20 min, then homogenize and degas to obtain the finished product.

[0048] Example 3

[0049] A long-life and low-friction grease composition is prepared by the following steps:

[0050] S1, mix 3.5 kg of high-base calcium sulfonate and 7 kg of poly-α-olefin base oil, stir evenly and heat up to 70 °C;

[0051] S2, add 0.25 kg of conversion agent and stir evenly, heat up to 85 °C, react for 1 h, then continue to add 0.2 kg of 5,5-dimethylhydantoin and 0.2 kg of hydroxymethylurea and stir evenly, and keep warm for 1 h;

[0052] S3, control the temperature at 90 °C, add 0.15 kg of calcium hydroxide and stir for 10 min, then add 0.4 kg of dodecahydroxystearic acid for saponification reaction, and the saponification time is 2 h;

[0053] S4, cool down to below 90 °C, add 0.12 kg of sodium carboxymethyl cellulose, 0.08 kg of sodium stearate, 0.2 kg of molybdenum dioxide nanometer, 0.2 kg of N-phenyl-α-naphthylamine and 0.2 kg of passivator TH551 and stir for 20 min, then homogenize and degas to obtain the finished product.

[0054] Example 4

[0055] A long-life and low-friction grease composition is prepared by the following steps:

[0056] S1, mix 3.2 kg of high-base calcium sulfonate and 6.5 kg of poly-α-olefin base oil, stir evenly and heat up to 90 °C;

[0057] S2, add 0.2 kg of conversion agent and stir evenly, heat up to 93 °C, react for 1 h, then continue to add 0.15 kg of 5,5-dimethylhydantoin and 0.2 kg of hydroxymethylurea and stir evenly, and keep warm for 1 h;

[0058] S3, control the temperature at 90 °C, add 0.12 kg of calcium hydroxide and stir for 10 min, then add 0.32 kg of hydrogenated castor oil for saponification reaction, and the saponification time is 2 h;

[0059] S4, Cool down to below 90°C, add 0.1 kg of sodium carboxymethyl cellulose, 0.06 kg of sodium stearate, 0.1 kg of molybdenum dioxide nanometer, 0.1 kg of N-phenyl-α-naphthylamine and 0.1 kg of passivator TH551, and stir for 20 min, then homogenize and degas to obtain the finished product.

[0060] Example 5

[0061] A long-life and low-friction grease composition is prepared by the following steps:

[0062] S1, Mix 3.6 kg of overbased calcium sulfonate and 7.2 kg of poly-α-olefin base oil, stir evenly and heat up to 80°C;

[0063] S2, Add 0.3 kg of conversion agent and stir evenly, heat up to 96°C, react for 1 h, then continue to add 0.2 kg of 5,5-dimethylhydantoin and 0.25 kg of hydroxymethylurea and stir evenly, keep warm for 1 h;

[0064] S3, Control the temperature at 90°C, add 0.15 kg of calcium hydroxide and stir for 10 min, add 0.42 kg of hydrogenated castor oil for saponification reaction, and the saponification time is 2 h;

[0065] S4, Cool down to below 90°C, add 0.05 kg of sodium carboxymethyl cellulose, 0.06 kg of sodium stearate, 0.15 kg of molybdenum dioxide nanometer, 0.15 kg of N-phenyl-α-naphthylamine and 0.15 kg of passivator TH551, and stir for 20 min, then homogenize and degas to obtain the finished product.

[0066] Performance detection test

[0067] Perform performance tests on the greases prepared in Examples 1-5, and record the test results in Table 1 below.

[0068] Among them, the grease life test adopts the German standard DIN51821-2-2016, and the test conditions are: 120°C, axial load 1.5 kN, axial rotation speed 6000 r / min.

[0069] Table 1 Detection results of Examples 1-5

[0070]

[0071] It can be seen from the detection results in Table 1 that the grease composition prepared in this application has a long service life and excellent anti-friction performance, can effectively reduce the running resistance of lubricated parts, and reduce the wear during the operation of mechanical equipment.

[0072] Comparative example

[0073] Comparative example 1

[0074] A grease composition, which is different from that of Example 1 in that 2-hydroxydecanoic acid is used to replace dodecahydroxystearic acid, and the rest is the same as in Example 1.

[0075] Comparative Example 2

[0076] A grease composition, which is different from that of Example 1 in that 5,5-dimethylhydantoin is not added, and the dosage of hydroxymethylurea is increased to 0.2 kg, and the rest is the same as in Example 1.

[0077] Comparative Example 3

[0078] A grease composition, which is different from that of Example 1 in that hydroxymethylurea is not added, and the dosage of 5,5-dimethylhydantoin is increased to 0.2 kg, and the rest is the same as in Example 1.

[0079] Comparative Example 4

[0080] A grease composition, which is different from that of Example 1 in that sodium carboxymethyl cellulose and sodium stearate are not added, and the dosage of nano-molybdenum dioxide is increased to 0.2 kg, and the rest is the same as in Example 1.

[0081] Performance detection test

[0082] The greases prepared in Example 1 and Comparative Examples 1-4 were respectively subjected to performance tests, and the test results are shown in Table 2 below.

[0083] Table 2 Performance test results of Example 1 and Comparative Examples 1-4

[0084]

[0085]

[0086] From the test results of Example 1, Comparative Examples 2 and 3, it can be seen that the present application uses a combination of 5,5-dimethylhydantoin and hydroxymethylurea, which can greatly extend the service life of the grease. This is because after the two are combined, they can act as a catalyst for the crystal form transformation of amorphous calcium carbonate in overbased calcium sulfonate, so that the oil-soluble raw materials in the grease are completely transformed into thixotropy, and the generated grease system is stable.

[0087] From the test results of Example 1 and Comparative Example 4, it can be seen that by adding sodium carboxymethyl cellulose and sodium stearate in the present application, the two act together with nano-molybdenum dioxide, which can greatly increase the anti-friction ability of the grease composition.

[0088] The above are only the preferred embodiments of the present application, and the protection scope of the present application is not limited to the above embodiments. All technical solutions falling within the concept of the present application belong to the protection scope of the present application. It should be noted that for those of ordinary skill in the art, several improvements and refinements made without departing from the principle of the present application should also be regarded as within the protection scope of the present application.

Claims

1. A long-life low-friction grease composition, characterized in that: The composition comprises the following components by weight: 30-40 parts of high base calcium sulfonate, 60-80 parts of base oil, 1-3 parts of 5,5-dimethylhydantoin, 1-3 parts of hydroxymethyl urea, 0.5-2 parts of sodium hydroxymethyl cellulose, 0.5-1 parts of sodium stearate, 1-4 parts of converting agent, 1-2 parts of calcium hydroxide, C 12 -C 20 3-5 parts of hydroxy fatty acid, 1-3 parts of solid friction reducer, 1-3 parts of antioxidant, 1-3 parts of passivator; the conversion agent is a mixture of isopropanol and glacial acetic acid; The long-life low-friction grease composition is prepared by the following preparation steps: S1, mix the overbased calcium sulfonate and base oil, stir evenly and heat to 70-90°C; S2, add the conversion agent and stir evenly, heat to 85-100°C, react for 0.5-1h, continue to add 5,5-dimethylhydantoin and hydroxymethyl urea and stir evenly, keep warm for 0.5-1h; S3, control the temperature at 90-100℃, add calcium hydroxide and stir for 5-10min, then add C 12 -C 20 Hydroxy fatty acids undergo saponification reaction, and the saponification time is 1-2h; S4, cool down to below 90°C, add sodium hydroxymethyl cellulose, sodium stearate, solid friction reducer, antioxidant and passivator and stir for 10-20 minutes, homogenize and deaerate to obtain the finished product.

2. The long-life low-friction grease composition according to claim 1, characterized in that: The base oil is selected from one or more of hydrogenated mineral oil, polyalphaolefin synthetic oil and naphthenic base oil.

3. The long-life low-friction grease composition according to claim 1, characterized in that: The base value of the high base calcium sulfonate is 400-450 mgKOH·g -1 , the calcium content is 15-16% by mass.

4. The long-life low-friction grease composition according to claim 1, characterized in that: The solid friction reducer is selected from one of nano tungsten dioxide and nano molybdenum dioxide.

5. The long-life low-friction grease composition according to claim 1, characterized in that: The antioxidant is selected from diphenylamine or phenyl-α-naphthylamine.

6. The long-life low-friction grease composition according to claim 1, characterized in that: The passivating agent is selected from one of benzotriazole derivatives, thiadiazole derivatives and heterocyclic compounds.

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