Special lubricating grease for spindle bearing and preparation method thereof

Abstract

The invention relates to the technical field of lubricating grease, in particular to special lubricating grease for a spindle bearing, which comprises the following components in percentage by mass: 73-76% of base oil; 17%-20% of 12-hydroxy stearic acid; 1.75% to 2.06% of lithium hydroxide monohydrate; 0.75%-0.88% of calcium hydroxide powder; 1.2%-1.8% of a structure improver; 0.5%-0.7% of an antirust agent; 0.3%-0.5% of an antioxidant; 0.1%-0.3% of a metal deactivator; 1.5%-2.0% of an anti-wear reagent at extreme pressure; the extreme pressure anti-wear agent is a mixture of zinc dialkyl dithiophosphate and molybdenum dibutyl dithiocarbamate in a mass ratio of 1: 1. The similar viscosity of the lubricating grease at-50 DEG C is less than 1100 Pa.s, and the lubricating grease has excellent pumpability. The working penetration of the lubricating grease is almost similar to the non-working penetration of the lubricating grease, and the working penetration change value is 0.1 mm, which indicates that the lubricating grease has better mechanical stability. The metal surface adhesive force of the lubricating grease is high, and the working noise value is low and is smaller than 20 db.

Description

Technical Field

[0001] The invention belongs to the technical field of lubricating grease, and particularly relates to a special lubricating grease for spindle bearings. Background Art

[0002] Spindle bearings are mainly used in textile machinery spindles used in conjunction with cotton, wool, linen, chemical fiber, pure spinning and blended spinning machines and twisting machines. The high-speed operation of the bearings requires full lubrication, and grease should be added regularly according to the actual situation. For enterprises, it is particularly important to choose better and more suitable grease. During the operation of the textile machinery, the spindle bearings will be subject to greater friction and vibration, which will cause the bearings to produce certain environmental noise. High-speed bearings have higher requirements on the colloidal properties of the grease. The centrifugal force causes a large amount of base oil to be separated and lost, resulting in bearing failure and damage due to poor lubrication, which seriously affects production efficiency. The function of special grease for spindle bearings is to reduce friction, prevent wear, reduce noise, and provide the necessary protection and sealing for the bearings.

[0003] The general operating temperature of the spindle bearings of textile machinery is 65-70℃, and the speed reaches 3000r / min-3600r / min. The spindle bearings have a small diameter and a fast speed. The grease used is usually prepared with a low-viscosity base oil. Therefore, the colloid properties of the grease and the high temperature resistance of the base oil are particularly important. Otherwise, the base oil will be lost and evaporated in a short time, which will change the grease viscosity, reduce lubricity or fail. In severe cases, it will cause bearing damage, seriously affecting the production of the enterprise. Summary of the invention

[0004] The technical problem to be solved by the present invention is to provide a special lubricating grease for spindle bearings and a preparation method thereof, so as to ensure effective lubrication of the bearings and extend the service life of the equipment.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A special lubricating grease for a spindle bearing, wherein the lubricating grease comprises, calculated by mass percentage:

[0007] Base oil: 73%~76%;

[0008] Dodecyl hydroxystearic acid: 17% to 20%;

[0009] Lithium hydroxide monohydrate: 1.75%~2.06%;

[0010] Calcium hydroxide powder: 0.75% to 0.88%;

[0011] Structural improver: 1.2%~1.8%;

[0012] Rust inhibitor: 0.5% to 0.7%;

[0013] Antioxidant: 0.3% to 0.5%;

[0014] Metal deactivator: 0.1% to 0.3%;

[0015] Extreme pressure anti-wear agent: 1.5% to 2.0%; the extreme pressure anti-wear agent is a mixture of zinc dialkyl dithiophosphate and molybdenum dibutyl dithiocarbamate in a mass ratio of 1:1.

[0016] The base oil is a mixture of polyalphaolefin base oil 1, polyalphaolefin base oil 2 and diester base oil in a mass ratio of 7.5-7.8:1:1.8-2.

[0017] The rust inhibitor is neutral barium dinonylnaphthalenesulfonate.

[0018] The structure improver is a mixture of glycerol and oleic acid in a mass ratio of 2:1.

[0019] The antioxidant is a methylbenzotriazole compound.

[0020] The metal deactivator is a thiadiazole derivative.

[0021] A method for preparing a special lubricating grease for a spindle bearing comprises the following steps:

[0022] 1) Premixed base oil: Mix the polyalphaolefin base oil 2, the diester base oil and 1 / 5 to 1 / 4 of the polyalphaolefin base oil 1 for later use;

[0023] 2) Mix lithium hydroxide monohydrate with 6-7 times water to dissolve, control the temperature at 75-80 degrees, filter and set aside;

[0024] 3) Add the remaining polyalphaolefin base oil 1 and 7 / 10 of dodecyl hydroxystearic acid into the reactor, stir and heat to 85-90 degrees, and keep warm for 3-5 minutes;

[0025] 4) One-step saponification: Add the material obtained in step 2) into a reactor and perform saponification reaction at 90-95 degrees for 30-40 minutes;

[0026] 5) One-step refining: the material in the reactor is heated to 170-180 degrees, kept warm for 10-15 minutes, and the water is discharged at the same time;

[0027] 6) Add oil and cool down: add the base oil prepared in step 1) into the reactor, and the temperature of the material in the reactor drops below 100°C;

[0028] 7) Control the temperature of the materials in the reactor to 120-125 degrees, add calcium hydroxide powder and stir evenly;

[0029] 8) Second step saponification: the remaining dodecyl hydroxystearic acid is added to the reactor in several portions, and the saponification reaction is carried out at 120-125 degrees for 50-60 minutes, and the water is discharged at the same time;

[0030] 9) Two-step refining: The materials in the reactor are heated to 140-145 degrees and kept warm for 20-30 minutes; then the materials in the reactor are cooled to 115-120 degrees, the structure improver is added, stirred for 20-30 minutes, and the averaging machine is turned on for circulation treatment;

[0031] 10) The temperature of the reactor material is controlled at 85-100 degrees, and antioxidant, metal deactivator, rust inhibitor and extreme pressure anti-wear agent are added in sequence, stirred and mixed for 5-10 minutes, and intermittently stirred and filtered for 50-60 minutes;

[0032] 11) Degassing packaging.

[0033] Step 1) Premixing base oil operation method: introduce polyalphaolefin base oil 1, polyalphaolefin base oil 2 and diester base oil into the base oil premixing tank through a flow meter, control the temperature at 30-40 degrees, and premix and stir for 10-15 minutes.

[0034] In step 2), lithium hydroxide monohydrate is mixed with water in an alkali dissolving tank, the temperature is controlled at 75-80 degrees, and filtered through a 300-400 mesh filter for standby use.

[0035] Step 5) During the one-step refining process, the reactor is opened to induce air to discharge water in the material system.

[0036] Step 8) During the second-step saponification process, the reactor is opened to induce air to discharge the free water generated during the reaction.

[0037] Step 10) Intermittent stirring filtration method: filtration through a 200-mesh filter, with an intermittent stirring cycle of starting stirring for 2 to 3 minutes and stopping for 7 to 8 minutes.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] In terms of base oil selection, low-viscosity polyalphaolefins are mainly used, combined with low-viscosity diesters and even lower-viscosity polyalphaolefins. Diester base oils can improve the pumping performance of grease and have excellent high-temperature resistance.

[0040] The rust inhibitor is neutral barium dinonylnaphthalene sulfonate, and the synthetic sulfonate component has an excellent rust-proof effect on steel and copper metals in hot and humid environments.

[0041] The extreme pressure anti-wear agent is a mixture of zinc dialkyl dithiophosphate and molybdenum dibutyl dithiocarbamate in a mass ratio of 1:1. The two agents are compatible and have good anti-wear properties under low loads and excellent extreme pressure properties under high loads. The molecular structure of the ester base oil in the material contains polar groups such as carbonyl oxygen and alcohol oxygen, which are closer to the polarity of the extreme pressure anti-wear agent. According to the principle of like dissolves like, it can better dissolve the additives, thereby achieving the best extreme pressure and anti-wear effect.

[0042] The antioxidant is a methylbenzotriazole compound, a liquid ashless antioxidant that can effectively extend the oxidation life of grease.

[0043] The metal deactivator is a thiadiazole polysulfide, which is a copper corrosion inhibitor and a non-ferrous metal deactivator. It has excellent oil solubility, can capture active sulfur in oil, inhibit metal corrosion, and has excellent extreme pressure and anti-wear properties.

[0044] Dodecyl hydroxystearic acid reacts with lithium hydroxide monohydrate to obtain dodecyl hydroxystearic acid lithium soap (metal soap), and dodecyl hydroxystearic acid reacts with calcium hydroxide to obtain dodecyl hydroxystearic acid calcium soap (metal soap). Dodecyl hydroxystearic acid lithium soap presents double helical ribbon-like fibers. Dodecyl hydroxystearic acid calcium soap is a single fiber. The mass ratio of dodecyl hydroxystearic acid lithium soap and dodecyl hydroxystearic acid calcium soap in the grease product is 7:3 (the coefficient of added alkali calculated by the molar number of acid-base reaction is 0.147), which makes the grease have better colloidal properties and reduces the amount of oil separation in the grease.

[0045] The structure improver is glycerol and oleic acid in a mass ratio of 2:1. It is a highly polar compound that can improve the grease colloidal stability and reduce the grease oil separation. The steel mesh oil separation is less than 2%, and the pressure oil separation is less than 15%. The consistency is kept good.

[0046] The lubricating grease of the present invention has a similar viscosity of less than 1100 Pa.s at -50°C, and the lubricating grease has excellent pumpability. The working cone penetration of the lubricating grease is almost similar to the non-working cone penetration, and the working cone penetration change value is 0.1mm, indicating that the lubricating grease has relatively good mechanical stability. The metal surface adhesion of the lubricating grease is strong, and the working noise value is low, which is less than 20db.

[0047] In terms of technology, a step-by-step reaction preparation method is adopted. In one step of saponification reaction, in a water environment, dodecyl stearic acid reacts with lithium hydroxide monohydrate to form dodecyl stearic acid lithium soap. Then, a step of refining is performed, and the temperature of the refining is controlled at 170-180 degrees. The dodecyl stearic acid lithium soap fiber can reach the gel state from the pseudo-gel state (phase transition temperature above 170 degrees). The mechanical stability of the gel state soap structure is better than that of the pseudo-gel state. However, if the refining temperature is too high, the thickening ability will become stronger, and high soap thickening cannot be achieved. Therefore, the refining temperature is controlled at 170-180 degrees, which makes it have good mechanical stability while also ensuring the thickening agent content.

[0048] In the two-step saponification reaction, the temperature drops to 120-125 degrees under anhydrous high-temperature conditions. Dodecyl hydroxystearic acid, as an organic acid, can release protons (H+); and calcium hydroxide, as a base, can accept protons. In an anhydrous environment, the two substances directly undergo a neutralization reaction through proton transfer. During the reaction process, the protons in the organic acid are accepted by calcium hydroxide to form the corresponding organic acid salt and produce a small amount of free water. Under the temperature control of 120-125 degrees, the draft in the kettle is turned on, and dodecyl hydroxystearic acid is added in batches to prevent the concentrated generation of free water, facilitate the rapid discharge of water from the material system, avoid the hydrolysis of ester oils, and avoid the problem of tank swelling and overflow caused by the reaction of dodecyl hydroxystearic acid and calcium hydroxide in a water environment.

[0049] The two structural improvers are refined in the second step, added into the kettle, stirred and the homogenizer is turned on for processing, so as to make the polar ends of the two structures closely combine with the metal soap fibers, avoid interference from subsequent additives, and ensure the best anti-oil separation ability.

[0050] In the later stage of preparation, intermittent stirring and filtration method is adopted, and the grease has excellent thixotropy and consistency stability for long-term storage.

[0051] The advantages of the step-by-step reaction method of the present invention are as follows: 1. The reaction can be carried out in a full kettle under an anhydrous environment (maximum production at the capacity of the production kettle), and no space for a rising tank in the kettle is reserved, resulting in a high yield. 2. Hydrolysis of ester oils is avoided. 3. High soap thickening can be achieved, reducing the amount of oil separation. DETAILED DESCRIPTION

[0052] It should be noted that, unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by technicians in the technical field of this application; the terms used in the specification of the application herein are only for the purpose of describing specific embodiments and are not intended to limit the present application. The reference to "embodiment" in this article means that the specific features, structures or characteristics described in conjunction with the embodiment may be included in at least one embodiment of the present application. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0053] A special lubricating grease for spindle bearings, wherein the mass percentage of each component in the lubricating grease is:

[0054] Base oil: 73% to 76%, the base oil is a mixture of polyalphaolefin base oil 1, polyalphaolefin base oil 2 and diester base oil in a mass ratio of 7.5 to 7.8:1:1.8 to 2. 40 degree kinematic viscosity 14 to 16 mm 2 / s, the base oil viscosity is determined by the bearing size and rotation speed. The use of polyalphaolefin and diester base oils in combination first ensures the thickness of the oil film on the rolling elements of the bearing, while also meeting the high-temperature anti-volatility and low-temperature pumping properties of the grease.

[0055] Dodecyl hydroxystearic acid: 17%~20%, melting point 76~78℃.

[0056] Lithium hydroxide monohydrate: 1.75%~2.06%.

[0057] Calcium hydroxide powder: 0.75%~0.88%.

[0058] Structure improver: 1.2% to 1.8%, wherein the structure improver is propylene glycol and oleic acid in a mass ratio of 2:1, and is a compound with strong polarity. Adding it can improve the colloid properties of the grease, make the grease system more stable, and avoid base oil separation caused by the grease under high-speed operation of the spindle bearing.

[0059] Rust inhibitor: 0.5% to 0.7%. The rust inhibitor is neutral barium dinonylnaphthalenesulfonate, a synthetic sulfonate component, which has an excellent rust-proof effect on steel and copper metals in a hot and humid environment.

[0060] Extreme pressure anti-wear agent: 1.5% to 2.0%. The extreme pressure anti-wear agent is a mixture of zinc dialkyl dithiophosphate and molybdenum dibutyl dithiocarbamate in a mass ratio of 1:1, which achieves excellent extreme pressure anti-wear effect and can be well dissolved in diester oil, with the best anti-wear performance.

[0061] Antioxidant: 0.3% to 0.5%, wherein the antioxidant is a methylbenzotriazole compound, a liquid ashless antioxidant, which can effectively prolong the oxidation life of the grease.

[0062] Metal deactivator: 0.1% to 0.3%. The metal deactivator is thiadiazole polysulfide, which is a copper corrosion inhibitor and non-ferrous metal deactivator. It has excellent oil solubility, can capture active sulfur in oil products, inhibit metal corrosion, and has excellent extreme pressure and anti-wear properties.

[0063] A method for preparing a special lubricating grease for a spinning machine, comprising the following steps:

[0064] 1) Premixed base oil: Mix 1 / 5 to 1 / 4 of polyalphaolefin base oil 1, polyalphaolefin base oil 2 and diester base oil, control the temperature at 30 to 40 degrees, premix and stir for 10 to 15 minutes, and set aside.

[0065] 2) Alkali dissolving process: transfer lithium hydroxide monohydrate into the alkali dissolving tank and mix it with 6-7 times water, control the temperature at 75-80 degrees, filter through a 300-400 mesh filter to obtain lithium hydroxide alkaline water.

[0066] 3) The remaining polyalphaolefin base oil 1 is transferred into the reactor, 7 / 10 of dodecyl hydroxystearic acid is added, planetary bidirectional stirring is turned on, the temperature is raised to 85-90 degrees, and the temperature is kept for 3-5 minutes.

[0067] 4) One-step saponification: Add the lithium hydroxide alkaline water obtained in step 2) into the reactor and perform saponification reaction at 90-95 degrees for 30-40 minutes. In this process, the melted dodecyl hydroxystearic acid and lithium hydroxide monohydrate react under planetary bidirectional stirring to obtain dodecyl hydroxystearic acid lithium soap. The finished product has a fine and bright appearance.

[0068] 5) One-step refining: Open the reactor to draught, raise the temperature to 170-180 degrees, and keep warm for 10-15 minutes.

[0069] In this process, the refining temperature is controlled at 170-180 degrees, and the dodecyl stearate lithium soap fiber changes from a pseudo-gel state to a gel state. By improving the colloidal properties, the oil separation of the grease is improved, and the grease has good mechanical stability while ensuring the thickener content. During the refining process, the water in the reactor is discharged by the induced draft fan.

[0070] 6) Add oil and cool down: add the premixed base oil in step 1) into the reactor, and reduce the temperature of the material in the reactor to below 120 degrees;

[0071] In this process, in order to avoid the hydrolysis of ester oil and the high-temperature volatilization of low-viscosity polyalphaolefin light components, premixed base oil is added in this step.

[0072] 7) Control the temperature of the reactor material to 120-125 degrees, add calcium hydroxide powder and stir for 5-10 minutes.

[0073] 8) Second-step saponification: The remaining dodecyl hydroxystearic acid is added to the reactor in several portions at 120-125 degrees for saponification reaction for 50-60 minutes.

[0074] In this process, the saponification reaction is a water-free addition reaction method. Dodecahydroxystearic acid and calcium hydroxide powder are in direct contact under anhydrous conditions. The reaction temperature is 120-125 degrees. During this period, the air in the kettle is turned on to cause a small amount of free water generated by the dodecahydroxystearic acid and calcium hydroxide added in batches to be separated from the material in time under high temperature and negative pressure.

[0075] 9) Second step refining: The material in the reactor is heated to 140-145 degrees, kept warm for 20-30 minutes, then cooled to 115-120 degrees, the structure improver is added, stirred for 20-30 minutes, and the averaging machine is turned on for circulation.

[0076] During the cooling process after the second-step refining, the structure improvers propylene glycol and oleic acid are added into the kettle, stirred and the homogenizer is turned on for processing. The purpose is to tightly combine the polar ends of the two structures with the soap fibers to avoid competitive adsorption caused by the subsequent addition of additives, which affects the anti-oil separation ability.

[0077] 10) The temperature of the materials in the reactor is controlled at 85-100 degrees, and antioxidants, metal deactivators, rust inhibitors and extreme pressure anti-wear agents are added in sequence, stirred and mixed for 5-10 minutes, and filtered through 200 mesh for 50-60 minutes, during which stirring is started for 2-3 minutes and stopped for 7-8 minutes. This process uses intermittent stirring and filtering, and the grease has excellent thixotropy and consistency stability for long-term storage.

[0078] 11) Degassing and packaging: Transfer the material from step 10) to a degassing kettle, degassing pressure -0.07 to -0.09 MPa, and package.

[0079] The technical solutions in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0080] The specific components and component contents (in terms of mass percentage) of the special grease for spindle bearings provided in Examples 1-8 are shown in Table 1 (where "-" represents that the component is not added in this example):

[0081] Table 1:

[0082]

[0083]

[0084] The base oil in Table 1 is a mixture of PAO4 (polyalphaolefin), PAO2 (polyalphaolefin) and DA31 (diester). The process parameters of the spindle bearing special grease provided in Examples 1 to 8, step 1) to step 10), are shown in Table 2:

[0085] Table 2:

[0086]

[0087]

[0088] Product performance test:

[0089] The following testing equipment was used to test and evaluate the special lubricating greases for spindle bearings prepared in the eight embodiments. The test results are shown in Table 3:

[0090] Table 3:

[0091]

[0092]

[0093] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and basic spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A special lubricating grease for spindle bearings, characterized in that: The lubricating grease includes, by weight percentage: Base oil: 73%~76%; Dodecyl hydroxystearic acid: 17% to 20%; Lithium hydroxide monohydrate: 1.75%~2.06%; Calcium hydroxide powder: 0.75% to 0.88%; Structural improver: 1.2%~1.8%; Rust inhibitor: 0.5% to 0.7%; Antioxidant: 0.3% to 0.5%; Metal deactivator: 0.1% to 0.3%; Extreme pressure anti-wear agent: 1.5% to 2.0%; the extreme pressure anti-wear agent is a mixture of zinc dialkyl dithiophosphate and molybdenum dibutyl dithiocarbamate in a mass ratio of 1:

1.

2. The special lubricating grease for spindle bearings according to claim 1, characterized in that: The base oil is a mixture of polyalphaolefin base oil 1, polyalphaolefin base oil 2 and diester base oil in a mass ratio of 7.5-7.8:1:1.8-2.

3. The special lubricating grease for spindle bearings according to claim 1, characterized in that: The rust inhibitor is neutral barium dinonylnaphthalenesulfonate.

4. The special lubricating grease for spindle bearings according to claim 1, characterized in that: The structure improver is a mixture of glycerol and oleic acid in a mass ratio of 2:

1.

5. The special lubricating grease for spindle bearings according to claim 1, characterized in that: The antioxidant is a methylbenzotriazole compound.

6. The special lubricating grease for spindle bearings according to claim 1, characterized in that: The metal deactivator is a thiadiazole derivative.

7. The method for preparing a special lubricating grease for spindle bearings according to claim 1, characterized in that: The steps include: 1) Premixed base oil: Mix the polyalphaolefin base oil 2, the diester base oil and 1 / 5 to 1 / 4 of the polyalphaolefin base oil 1 for later use; 2) Mix lithium hydroxide monohydrate with 6-7 times water to dissolve, control the temperature at 75-80 degrees, filter and set aside; 3) Add the remaining polyalphaolefin base oil 1 and 7 / 10 of dodecyl hydroxystearic acid into the reactor, stir and heat to 85-90 degrees, and keep warm for 3-5 minutes; 4) One-step saponification: Add the material obtained in step 2) into a reactor and perform saponification reaction at 90-95 degrees for 30-40 minutes; 5) One-step refining: the material in the reactor is heated to 170-180 degrees, kept warm for 10-15 minutes, and the water is discharged at the same time; 6) Add oil and cool down: add the base oil prepared in step 1) into the reactor, and the temperature of the material in the reactor drops below 100°C; 7) Control the temperature of the materials in the reactor to 120-125 degrees, add calcium hydroxide powder and stir evenly; 8) Second step saponification: the remaining dodecyl hydroxystearic acid is added to the reactor in several portions, and the saponification reaction is carried out at 120-125 degrees for 50-60 minutes, and the water is discharged at the same time; 9) Two-step refining: The materials in the reactor are heated to 140-145 degrees and kept warm for 20-30 minutes; then the materials in the reactor are cooled to 115-120 degrees, the structure improver is added, stirred for 20-30 minutes, and the averaging machine is turned on for circulation treatment; 10) The temperature of the reactor material is controlled at 85-100 degrees, and antioxidant, metal deactivator, rust inhibitor and extreme pressure anti-wear agent are added in sequence, stirred and mixed for 5-10 minutes, and intermittently stirred and filtered for 50-60 minutes; 11) Degassing packaging.

8. The method for preparing a special lubricating grease for spindle bearings according to claim 7, characterized in that: Step 1) Premixing base oil operation method: introduce polyalphaolefin base oil 1, polyalphaolefin base oil 2 and diester base oil into the base oil premixing tank through a flow meter, control the temperature at 30-40 degrees, and premix and stir for 10-15 minutes.

9. The method for preparing a special lubricating grease for spindle bearings according to claim 7, characterized in that: In step 2), lithium hydroxide monohydrate is mixed with water in an alkali dissolving tank, the temperature is controlled at 75-80 degrees, and filtered through a 300-400 mesh filter for standby use.

10. The method for preparing a special lubricating grease for spindle bearings according to claim 7, characterized in that: In step 10), the intermittent stirring filtration method is as follows: filtering through a 200-mesh filter, and the intermittent stirring cycle is to start stirring for 2 to 3 minutes and stop stirring for 7 to 8 minutes.

Images