CN113652285A

CN113652285A - Refrigerating machine oil composition and preparation method thereof

Info

Publication number: CN113652285A
Application number: CN202111044666.3A
Authority: CN
Inventors: 詹翔智; 徐嘉; 史正良; 郭小青; 王银亮; 田文华
Original assignee: Gree Green Refrigeration Technology Center Co Ltd of Zhuhai
Current assignee: Gree Green Refrigeration Technology Center Co Ltd of Zhuhai; Zhuhai Gree Energy Saving Environmental Protection Refrigeration Technology Research Center Co Ltd
Priority date: 2021-09-07
Filing date: 2021-09-07
Publication date: 2021-11-16

Abstract

The application provides a refrigerator oil composition and a preparation method thereof. The refrigerator oil composition comprises base oil and polytetrafluoroethylene particles, wherein the particle size of the polytetrafluoroethylene particles is in a nanometer level; the polytetrafluoroethylene particles are uniformly dispersed in the base oil; the mass concentration of the polytetrafluoroethylene particles is 0.01-1%. Polytetrafluoroethylene particles are uniformly dispersed in base oil to form the refrigerating machine oil composition, and a more stable dispersion system is easily formed and agglomeration is avoided because of the small mass concentration of the polytetrafluoroethylene particles; the friction surfaces are separated by the nano polytetrafluoroethylene particles in the friction process, so that the actual contact area of the friction surfaces is reduced, and under a smaller load, the spherical nano particles can roll between the friction surfaces in the sliding friction process, so that the sliding friction is converted into the mixing of the sliding friction and the rolling friction, and the friction coefficient is obviously reduced.

Description

Refrigerating machine oil composition and preparation method thereof

Technical Field

The application belongs to the technical field of compressor oil, and particularly relates to a refrigerator oil composition and a preparation method thereof.

Background

As the performance of the refrigerating machine oil is required to be more and more enhanced with the increase in the speed and efficiency of the refrigeration compressor, it is necessary to improve various performances of the refrigerating machine oil base oil by adding various highly efficient additives. In order to reduce the wear of compressor parts, the friction and wear performance of the refrigerator oil is generally improved by adding phosphorus and sulfur anti-wear additives such as phosphate compounds, but these additives still have several disadvantages, such as: the environment is more harmful, the anti-wear effect is common, the stability is not good, the parts of the compressor can be corroded, the dosage is larger, and the like.

In recent years, researchers have focused more on nanomaterials as anti-wear additives. The nano particles have excellent performances of nano size effect, high strength, high diffusivity and the like, and can be added into base oil to form a stable dispersion system, so that the bearing capacity of the lubricating oil can be increased, and the anti-friction and anti-wear effects are achieved. In the friction process, the nano particles can permeate into the friction surface to form a friction film between the friction pairs, so that the load bearing capacity of the lubricating film can be improved, the friction surface can be separated, the spherical nano particles can roll between the friction surfaces in the sliding friction process to convert the sliding friction into the mixture of the sliding friction and the rolling friction, and the friction coefficient is obviously reduced. However, the key point is whether the nanoparticles can be stably dispersed in the base oil to form a stable and uniform lubricating system.

The modified polytetrafluoroethylene superfine powder is proposed to be used in lubricating oil as an antiwear agent of the lubricating oil, secondary abrasion to mechanical equipment is avoided, the friction coefficient is not increased, and the modified polytetrafluoroethylene superfine powder in the lubricating oil is large in addition amount, easy to agglomerate and not suitable for being used in a compressor.

Disclosure of Invention

Therefore, the application provides a refrigerator oil composition and a preparation method thereof, which can solve the problems that a polytetrafluoroethylene particle antiwear agent is easy to agglomerate and is not suitable for a compressor in the prior art.

In order to solve the above problems, the present application provides a refrigerator oil composition comprising:

the base oil and the polytetrafluoroethylene particles, the particle size of the polytetrafluoroethylene particles is set to be nanometer; the polytetrafluoroethylene particles are uniformly dispersed in the base oil;

the mass concentration of the polytetrafluoroethylene particles is 0.01-1%.

Optionally, the polytetrafluoroethylene particles have a particle size of 500nm or less.

Optionally, the refrigerator oil composition further comprises a proper amount of additives, wherein the additives comprise one or more of an antioxidant, an antiwear agent, a metal deactivator, an acid scavenger and an anti-foaming agent.

Optionally, the base oil comprises at least one of a mineral oil and a synthetic oil; the synthetic oil includes at least one of an ester, an ether, and a hydrocarbon oil.

Optionally, the hydrocarbon oil is provided as a hydrocarbon oil of poly-alpha-olefins and/or an alkylbenzene hydrocarbon oil.

According to another aspect of the present application, there is provided a method of preparing the refrigerator oil composition as described above, comprising:

pretreatment of polytetrafluoroethylene particles: adding polytetrafluoroethylene particles into a suspending agent, and stirring to form a suspension; adding a proper amount of surface modifier, and stirring until the surface modifier is uniformly dispersed; solid-liquid separation, drying the solid to obtain pretreated polytetrafluoroethylene particles;

and adding the pretreated polytetrafluoroethylene particles into the base oil, and uniformly dispersing.

Optionally, the suspending agent comprises at least one of methanol, ethanol, and aqueous solutions of the two.

Optionally, the surface modifier comprises one or more of phosphate ester salts, sulfonate salts, sulfate salts, fatty acid ester salts.

Optionally, the surface modifier is sodium lauryl sulfate.

Optionally, in the pretreatment of the polytetrafluoroethylene particles, after the surface modifier is added, ultrasonic dispersion is adopted, and the time is more than or equal to 1 hour.

Optionally, after the ultrasonic dispersion, stirring is continuously carried out at 40-60 ℃ for more than or equal to 1 hour.

The present application provides a refrigerator oil composition comprising: the base oil and the polytetrafluoroethylene particles, the particle size of the polytetrafluoroethylene particles is set to be nanometer; the polytetrafluoroethylene particles are uniformly dispersed in the base oil; the mass concentration of the polytetrafluoroethylene particles is 0.01-1%.

Polytetrafluoroethylene particles are uniformly dispersed in base oil to form the refrigerating machine oil composition, and a more stable dispersion system is easily formed and agglomeration is avoided because of the small mass concentration of the polytetrafluoroethylene particles; the friction surfaces are separated by the nano polytetrafluoroethylene particles in the friction process, so that the actual contact area of the friction surfaces is reduced, and under a smaller load, the spherical nano particles can roll between the friction surfaces in the sliding friction process, so that the sliding friction is converted into the mixing of the sliding friction and the rolling friction, and the friction coefficient is obviously reduced.

Drawings

FIG. 1 is a four-ball friction test steel ball spot surface topography of the product of example 1 of the present application;

FIG. 2 is a four-ball friction test steel ball spot surface topography of a conventional commercial refrigerator oil.

Detailed Description

According to an embodiment of the present application, a refrigerator oil composition includes:

the mass concentration of the polytetrafluoroethylene particles is 0.01-1%.

The polytetrafluoroethylene with the preset mass concentration range is adopted in the refrigerator oil composition, so that the lubricating property and the stability of the polytetrafluoroethylene can be improved; if the amount is less than 0.01%, the lubricating performance of the refrigerator oil composition is not greatly improved, and if the amount is more than 1%, the nanoparticles may agglomerate due to van der Waals' forces, hydrogen bonds, and the like between particles under long-term standing or high shear rate, thereby clogging the cooling system pipes or affecting the stability of the lubricating film.

When the refrigerator oil composition is used, the friction surfaces are separated by the nano polytetrafluoroethylene particles in the friction process, the actual contact area of the friction surfaces is reduced, and under a smaller load, the spherical nano particles can roll between the friction surfaces in the sliding friction process, so that the sliding friction is converted into the mixture of the sliding friction and the rolling friction, and the friction coefficient is obviously reduced.

In the using process of the refrigerator oil composition, the nano polytetrafluoroethylene particles can separate the friction surface and fill up the damaged part in time by forming a single-layer or multi-layer protective film, and the nano polytetrafluoroethylene particles have a self-repairing function, so that the friction surface is always in a relatively flat state, the purpose of delaying the damage of parts is achieved, and the condition that the mild abrasion of the early friction surface is changed into the severe abrasion is avoided. Observing the surface morphology of the steel ball specks after the four-ball friction experiment by using a white light interferometer, as shown in figures 1 and 2, and combining the contents shown in the table 2 in the embodiment, the specks after the friction of the commercial refrigerator oil have deep furrows and uneven edges; after the refrigerator oil containing the nano polytetrafluoroethylene particles is rubbed, the surface of the grinding spot is smooth and flat, and the diameter and the friction coefficient of the grinding spot are small.

Because the polytetrafluoroethylene particles have elastic properties, compared with the refrigerator oil composition containing other nano materials, the polytetrafluoroethylene particles can form a smooth friction film after being extruded and adhered in the friction process, and the friction coefficient is obviously reduced. In contrast, other hard and brittle nanoparticles may break up and remain on the rubbing surface, adversely affecting rubbing.

In some embodiments, the polytetrafluoroethylene particles have a particle size of 500nm or less.

The particle size of the polytetrafluoroethylene fine particles is limited to the above range, the refrigerator oil composition can obtain good dispersion stability and lubrication performance, and if the particle size is more than 500nm, the polytetrafluoroethylene fine particles may not be stably dispersed in the base oil, and a stable and uniform lubrication system may not be formed.

In some embodiments, the refrigerator oil composition further comprises an amount of an additive comprising one or more of an antioxidant, an antiwear agent, a metal deactivator, an acid scavenger, an anti-foam agent.

The refrigerator oil composition may contain additives in addition to the base oil and the nano polytetrafluoroethylene, in a range not to impair the effects of the present embodiment.

The additives to be blended in the refrigerator oil composition containing nano polytetrafluoroethylene according to the present embodiment are not particularly limited, and include, but are not limited to, antioxidants, anti-wear agents, metal deactivators, acid scavengers, and anti-foaming agents.

These additives may be used singly or in combination of two or more.

As an antioxidant, the antioxidant slows down the oxidation process of the lubricating oil and prolongs the working time of the lubricating oil. According to the oxidation process of the lubricating oil, the antioxidant has the action method that free radicals generated in the oxidation process are captured, and the oxidation process is stopped; another method of action is to decompose the peroxide to give a stable compound. Wherein, the antioxidant adopts free radical terminators such as phenol type antioxidant and amine type antioxidant, etc., and captures free radicals to slow down the oxidation process; examples of the phenolic antioxidants include 2, 6-di-t-butyl-p-cresol (BHT), 2, 6-di-t-butyl-4-methylphenol (DBPC), 2, 6-di-t-butyl-4-ethylphenol, and 2,2 '-methylenebis (4-methyl-6-t-butylphenol), and examples of the aminic antioxidants include phenyl- α -naphthylamine and N, N' -di-phenyl-p-phenylenediamine.

As an antiwear agent, some generate a multilayer deposited film thick enough to prevent contact of rough surfaces; some produce a replenishable monolayer film to reduce localized shear forces of rough surfaces in contact with each other and to be preferentially removed in place of surface material; some form chemical bonds with the surface and gradually change the surface roughness by controlling the removal of surface material. The antiwear agent comprises a phosphate antiwear agent, and can form an organic film or an inorganic film on the surface of metal at a higher temperature so that the metal is not in direct contact with the metal, thereby playing a role in protection. Specifically, phosphate, acid phosphate, phosphite, etc. The phosphate ester may be tricresyl phosphate, triphenyl thiophosphate, or the like; the acid phosphate may be monobutyl acid phosphate, dioleyl acid phosphate, etc.; the phosphite ester may be dibutyl phosphite, triphenyl phosphite, or the like.

As an antifoaming agent, foam on the surface of the refrigerator oil or in the system may adversely affect the lubrication system of the machine. The antifoaming agent can reduce the surface tension of the gas-liquid interface of the foam, so that the foam is broken and defoamed; the anti-foaming agent of the present application includes both silicon type and non-silicon type. The silicone-type antifoaming agent may be dimethicone. As the non-silicon type antifoaming agent, a homopolymer or a copolymer of an acrylate or a methacrylate may be mentioned. A composite antifoaming agent consisting of two or more antifoaming agents may also be used.

As a metal deactivator, the metal deactivator can play the following two roles: one is a film forming function, namely a chemical film is generated on the surface of the metal to prevent the metal or ions from entering the oil and weaken the catalytic oxidation effect of the metal on the oil, and the chemical film also has the function of protecting the surface of the metal and can prevent the corrosion of active sulfur, organic acid and the like on the surface of the metal; the other is complexation, which can complex with metal ions and can generate masking effect on the metal ions. The metal deactivator comprises benzotriazole and benzotriazole derivatives, thiadiazole and thiadiazole derivatives, heterocyclic compounds and the like. Examples of the benzotriazole and benzotriazole derivatives include benzotriazole, tolyltriazole and the like; examples of the thiadiazole and thiadiazole derivative include 2, 5-dimercapto-1, 3, 4-thiadiazole and the like.

The acid scavenger is capable of neutralizing an acidic product to form a neutral and stable substance, such as a glycidyl ester type epoxy compound, a glycidyl ether type epoxy compound, an oxirane compound, an alicyclic epoxy compound, etc. Specifically, the glycidyl ether may be n-butylphenyl glycidyl ether, t-butylphenyl glycidyl ether, polyalkylene glycol glycidyl ether, hexanediol diglycidyl ether, neopentyl glycol diglycidyl ether, neodecanoic acid glycidyl ester, or the like.

The amount of these additives added is not particularly limited, but is preferably 5% by mass or less based on the total amount of the refrigerator oil.

In some embodiments, the base oil comprises at least one of a mineral oil and a synthetic oil; the synthetic oil includes at least one of an ester, an ether, and a hydrocarbon oil.

The kinematic viscosity of the base oil of the refrigerator oil at 40 ℃ is preferably 5-150 mm²(ii)/s, the viscosity index is preferably 70 or more; the pour point is preferably-10 ℃ or lower, more preferably-20 ℃ or lower; the flash point is preferably 180 ℃ or higher, more preferably 200 ℃ or higher. In the case where the above parameters are satisfied, the base oil in the refrigerator oil may be at least one selected from mineral oils and synthetic oils.

The mineral oil that can be used as the base oil component includes, but is not limited to, any of paraffinic, naphthenic, and mixed base oils. Further, a lubricant component obtained by distilling one or a mixture of these mineral oils under atmospheric pressure and then under reduced pressure can be suitably used, and a purified lubricant component obtained by treating the lubricant component by suitably combining lubricant refining means such as solvent removal, solvent extraction, hydrorefining, hydrocracking, solvent dewaxing, hydrodewaxing, clay treatment and the like. A plurality of purified lubricating oil components having different properties obtained by combining various raw materials with various purification means may be used alone or in combination.

Synthetic oils that may be used as the base oil component include, but are not limited to, oxygen-containing compounds such as esters and ethers, or hydrocarbon oils such as poly-alpha-olefins and alkylbenzenes.

The ester as the base oil component is preferably a polyol ester having excellent stability. As the polyol ester, an ester of pentaerythritol, dipentaerythritol, or a linear or branched fatty acid having 5 to 9 carbon atoms is preferably used. The base oil of the refrigerator oil may be a mixture of various esters. Among them, the fatty acid is more preferably composed of a C5, C8, C9 linear or branched mixed acid, and specific examples thereof include n-valeric acid, 2-ethylpropionic acid, 2-methylbutyric acid, 3-methylbutyric acid, n-octanoic acid, 2-methylheptanoic acid, 3-methylheptanoic acid, 4-methylheptanoic acid, 5-methylheptanoic acid, 2-ethylhexanoic acid, 3-ethylhexanoic acid, 4-ethylhexanoic acid, 5-ethylhexanoic acid, n-nonanoic acid, 2-methyloctanoic acid, 3-methyloctanoic acid, 4-methyloctanoic acid, 5-methyloctanoic acid, 6-methyloctanoic acid, 7-methyloctanoic acid, 2-ethylheptanoic acid, 3-ethylheptanoic acid, 4-ethylheptanoic acid, 5-ethylheptanoic acid, 3,5, 5-trimethylhexanoic acid, 4-methyloctanoic acid, 6-methyloctanoic acid, 7-methyloctanoic acid, 2-ethylheptanoic acid, 3-ethylheptanoic acid, 4-ethylheptanoic acid, 5-trimethylhexanoic acid, 3,4, 5-trimethylhexanoic acid, 2-ethyl-3-methylhexanoic acid, 2-ethyl-4-methylhexanoic acid, 2-ethyl-5-methylhexanoic acid, and the like.

The ether as the base oil component may be a polyalkylene glycol, a polyvinyl ether, or the like.

In order to improve the dispersion stability of the nano-sized polytetrafluoroethylene particles in the base oil, the nano-sized polytetrafluoroethylene particles are subjected to surface modification when the refrigeration oil composition is prepared. Because the surface energy of the nano polytetrafluoroethylene is high, the nano polytetrafluoroethylene is easy to agglomerate in the application process. The surface modifier is a surfactant and consists of two groups with different properties, namely hydrophilic group and hydrophobic group, the hydrophilic group and the surface of the nano particles act together in the process of modifying the nano particles, so that the modifier is adsorbed to the surface of a solid, and the hydrophobic group enhances the oil solubility of the nano particles. For example, the polar head group of sodium dodecyl sulfate facilitates mixing with the base oil, while the non-polar tail group is attached to the nano-polytetrafluoroethylene particles, which lowers the surface energy of the nano-polytetrafluoroethylene particles and keeps them dispersed in the base oil.

Wherein the suspending agent comprises at least one of methanol, ethanol and aqueous solution of the methanol and the ethanol. The surface modifier includes phosphate ester salts, sulfonate salts, sulfate salts, fatty acid ester salts, etc., and among them, sodium lauryl sulfate is preferable.

In some embodiments, the polytetrafluoroethylene particles are pretreated by adding the surface modifier and then ultrasonically dispersing for 1 hour or more.

The ultrasonic dispersion is adopted to improve the dispersibility of the polytetrafluoroethylene particles, so that the stability can be improved.

In some embodiments, the ultrasonic dispersion is followed by continued stirring at 40-60 ℃ for 1 hour or more.

The temperature is set within the relatively constant temperature range, so that the dispersion stability can be enhanced.

The technical solution of the present application will be clearly and completely described below with reference to the following embodiments.

The base oil is a polyol ester, specifically an ester of pentaerythritol with two fatty acids, the specific composition and performance parameters of which are shown in table 1.

TABLE 1

The additives are respectively:

additive 1: sodium dodecyl sulfate modified nano polytetrafluoroethylene

Additive 2: unmodified nano polytetrafluoroethylene

Additive 3: sodium dodecyl sulfate modified nanometer NiFe2O4

Additive 4: sodium dodecyl sulfate modified nano cerium oxide compound

Additive 5: 2, 6-di-tert-butyl-p-cresol

Additive 6: trimethylphenol phosphate

Additive 7: tert-butylphenyl glycidyl ester

Additive 8: methylbenzotriazole

Additive 9: dimethyl silicone oil

Next, the following tests were carried out using the refrigerator oil compositions of examples 1 to 3 and comparative examples 1 to 6.

1. Standing sedimentation test

An equal amount of sample was placed in a test tube and placed vertically, the sample was observed for precipitation every 24 hours, and the time at which the sample began to precipitate was recorded. The dispersion stability of the sample was judged by the time at which precipitation started to occur, and the longer the time, the better the dispersion stability. The results obtained are shown in table 2.

2. Four-ball friction experiment

The standard according to which the test is carried out: SHT 0189-four-ball method for measuring abrasion resistance of lubricating oil

Test temperature: 75 deg.C

Test time: 1 hour

Loading: 392N

Rotating speed: 1200rpm

The examples and comparative examples were tested by the above test, and the wear resistance was evaluated by the size of the wear-scar diameter of the lower steel ball, and the smaller the wear-scar diameter, the better the wear resistance. The results obtained are shown in table 2.

3. Four-ball extreme pressure experiment

The standard according to which the test is carried out: GB/T3142-four-ball method for measuring bearing capacity of lubricant

The extreme pressure performance of each of the examples and comparative examples was evaluated by the above test using the maximum seizure-free load, and the greater the maximum seizure-free load, the better the extreme pressure performance. The results obtained are shown in table 2.

4. Falex Ring Block test

The standard according to which the test is carried out: ASTM D2714-Standard test method for calibrating and operating Faller Ring Block Friction tester and abrasion tester

Test materials: steel block and cast iron ring

Test start temperature: 25 deg.C

Test time: 1 hour

Rotating speed: 1000rpm

Loading: 100lbf

The wear resistance is evaluated by the width of a grinding mark and the size of a wear volume on a block sample by testing each example and each comparison by adopting the test, and the smaller the width of the grinding mark and the size of the wear volume is, the better the wear resistance is; the friction characteristics were evaluated by the average friction coefficient, and the smaller the average friction coefficient, the better the friction characteristics, and the results are shown in table 2.

TABLE 2

As can be seen from Table 2, the friction coefficients of the refrigerator oil compositions of the embodiments 1 to 3 are obviously superior to those of the comparative examples 1 to 6, the wear scar widths, the wear scar diameters and the maximum non-seizing loads are equivalent to those of the comparative examples 5 and 6, and are superior to those of the comparative examples 1 to 4, so that the refrigerator oil compositions containing the modified nano polytetrafluoroethylene can play a good role in resisting friction and wear, and the improvement on the friction performance is especially obvious. The settling time of the embodiments 1 to 3 is obviously higher than that of the comparative examples 3 and 4, and is slightly higher than that of the comparative examples 5 and 6, which shows that the dispersion stability of the surface-modified nano polytetrafluoroethylene in the refrigerator oil is good. In summary, it can be shown that the refrigerating machine oil composition containing the modified nano polytetrafluoroethylene has good dispersion stability and frictional wear performance.

It is easily understood by those skilled in the art that the above embodiments can be freely combined and superimposed without conflict.

The above description is only exemplary of the present application and should not be taken as limiting the present application, as any modification, equivalent replacement, or improvement made within the spirit and principle of the present application should be included in the protection scope of the present application. The foregoing is only a preferred embodiment of the present application, and it should be noted that, for those skilled in the art, several modifications and variations can be made without departing from the technical principle of the present application, and these modifications and variations should also be considered as the protection scope of the present application.

Claims

1. A refrigerating machine oil composition, comprising:

the mass concentration of the polytetrafluoroethylene particles is 0.01-1%.

2. The refrigerator oil composition according to claim 1, wherein the polytetrafluoroethylene fine particles have a particle size of 500nm or less.

3. The refrigerator oil composition of claim 1 or 2 further comprising an amount of additives including one or more of antioxidants, antiwear agents, metal deactivators, acid scavengers, anti-foam agents.

4. The refrigerator oil composition of claim 1, wherein the base oil comprises at least one of a mineral oil and a synthetic oil; the synthetic oil includes at least one of an ester, an ether, and a hydrocarbon oil.

5. The refrigerator oil composition according to claim 4, wherein the hydrocarbon oil is a hydrocarbon oil of a poly- α -olefin and/or an alkylbenzene hydrocarbon oil.

6. A method for preparing the refrigerator oil composition according to any one of claims 1 to 5, comprising:

7. The method of claim 6, wherein the suspending agent comprises at least one of methanol, ethanol, and aqueous solutions thereof.

8. The method of claim 6 or 7, wherein the surface modifier comprises one or more of phosphate ester salt, sulfonate, sulfate, and fatty acid ester salt.

9. The method according to claim 8, wherein the surface modifier is sodium lauryl sulfate.

10. The method according to claim 6, wherein the polytetrafluoroethylene fine particles are pretreated by adding a surface modifier and then ultrasonically dispersing for 1 hour or more.

11. The preparation method according to claim 10, wherein the ultrasonic dispersion is continued to be stirred at 40 to 60 ℃ for 1 hour or more.