A refrigeration oil composition, its preparation and use

Abstract

The application discloses a refrigeration oil composition and a preparation method and application thereof. The refrigeration oil composition of the application adopts a polyol ester base oil of pentaerythritol and di-pentaerythritol and short-chain acid structures of normal butyric acid, 2-ethylhexanoic acid and aliphatic carboxylic acid with a carbon atom number of 5-7, and a base oil of two components of a polyalkoxy ether base oil. By changing the proportion (or polymerization degree) and ratio of the two components, the two-phase separation temperature of the refrigeration oil composition and R290 refrigerant can be controlled, so that the application requirement of significantly improving the compatibility with R290 refrigerant is achieved. Meanwhile, the composition has good hydrolysis stability.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of industrial lubricating oil such as refrigeration machine oil, and particularly relates to a refrigeration machine oil composition, a preparation method and application thereof. BACKGROUND

[0002] In recent years, the refrigerant used in refrigeration machine oil tends to use a hydrofluorocarbon (HFC) refrigerant with zero ozone depletion potential (ODP) and lower global warming potential (GWP). In a domestic air conditioner refrigeration compressor, the currently used refrigerant is R410A, R22, etc., which has zero ODP but a high GWP value, and is gradually becoming a restricted and replaced refrigerant. Low hydrocarbons with a carbon number of 2-4 do not destroy the ozone layer and have very low impact on global warming, and therefore have recently attracted more and more attention. For example, isobutane (R600a) has been used as a refrigerant for refrigerators, and propane (R290) with a carbon number of 3 has begun to be applied to domestic air conditioner refrigerants.

[0003] As the refrigeration machine oil for low hydrocarbon refrigerants, mineral oils of naphthenic or paraffin series, alkylbenzene oils, ester oils, and polyether oils that are compatible with the refrigerant.

[0004] First, when the existing mineral oil, alkylbenzene, and polyol ester are used as lubricating oil, the lubricating oil and the R290 refrigerant are completely miscible, so the viscosity of the lubricating oil is reduced, the lubricating performance of the oil is reduced, and the wear resistance and sealing performance of the compressor are reduced, ultimately resulting in a significant reduction in the performance and service life of the compressor.

[0005] Second, although polyether lubricating oil has been widely used in automobile air conditioner compressor oils using R134A as a refrigerant, such polyether lubricating oil is not compatible with R290. If a refrigeration system uses a refrigeration machine oil that is not compatible with the refrigerant, the oil and the refrigerant can be easily stratified on the evaporator in the refrigeration system, and the refrigeration machine oil is not easily returned to the compressor in the refrigeration system, thereby causing a lack of oil in the moving parts of the compressor and affecting the reliability of the compressor. At the same time, the oil remaining in the evaporator can affect the heat exchange efficiency of the evaporator, resulting in a decrease in the efficiency of the refrigeration system.

[0006] Third, the refrigeration machine oil is a special lubricating oil for refrigeration compressors, and is a crucial component that determines and affects the refrigeration function and effect of the refrigeration system. A high-quality refrigeration machine oil must have excellent compatibility and hydrolytic stability when coexisting with the refrigerant. If the refrigeration machine oil contains a synthetic ester component, it is more likely to hydrolyze to produce acidic substances, causing corrosion problems of the metal parts inside the compressor.

[0007] Therefore, based on the above three aspects, how to select a refrigeration machine oil with appropriate solubility to the refrigerant while having good hydrolytic stability has become the key to solving the problem. SUMMARY

[0008] To improve the above technical problems, the present application provides a refrigeration oil composition and a preparation method and application thereof.

[0009] The refrigeration oil composition comprises a polyol ester base oil A and a polyalkoxy ether base oil B; the polyol ester base oil A comprises esters formed by a mixture of mono-pentaerythritol and fatty acids and esters formed by a mixture of di-pentaerythritol and fatty acids;

[0010] The mixture of fatty acids comprises n-butyric acid, 2-ethylhexanoic acid and aliphatic carboxylic acids with carbon atom number of 5-7;

[0011] The polyalkoxy ether base oil B has the following general formula:

[0012]

[0013] In the formula, R1 is a hydrogen atom or an alkyl group with carbon atom number of 1-5, R2 is a hydrogen atom, and m represents the average addition mole number of alkylene oxide, and m is a number between 15 and 22.

[0014] According to an embodiment of the present application, the molar ratio of mono-pentaerythritol and di-pentaerythritol is 1:(3-20), preferably 1:(5-10), for example, it can be 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, 1:11, 1:12, 1:13, 1:14, 1:15, 1:16, 1:17, 1:18, 1:19 or 1:20.

[0015] According to an embodiment of the present application, the mass ratio of n-butyric acid and 2-ethylhexanoic acid in the mixture of fatty acids can be 1:(0.5-8), preferably 1:(0.5-3), for example, 1:0.5, 1:1, 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4, 1:4.5, 1:5, 1:5.5, 1:6, 1:6.5, 1:7, 1:7.5 or 1:8.

[0016] According to an embodiment of the present application, the mass percentage of n-butyric acid in the mixture of fatty acids is 10-60%, preferably 15-45%, for example, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55% or 60%.

[0017] According to an embodiment of the present application, the mass ratio of n-butyric acid to the aliphatic carboxylic acid having 5 to 7 carbon atoms in the fatty acid mixture can be 1 : (0.2 to 5), preferably 1 : (0.4 to 2), for example 1 :0.2, 1 :0.5, 1 :1, 1 :1.5, 1 :2, 1 :2.5, 1 :3, 1 :3.5, 1 :4, 1 :4.5 or 1 :5.

[0018] According to an embodiment of the present application, the aliphatic carboxylic acid having 5 to 7 carbon atoms is selected from the group consisting of aliphatic carboxylic acids having 5, 6 or 7 carbon atoms, including isomers thereof, for example at least one selected from the group consisting of n-pentanoic acid, 2-methylbutanoic acid, 3-methylbutanoic acid, 2-methylpentanoic acid, 2-ethylbutanoic acid, 3-methylhexanoic acid, neohexanoic acid; preferably, the aliphatic carboxylic acid having 5 to 7 carbon atoms is at least one selected from the group consisting of n-pentanoic acid, 2-methylbutanoic acid, 3-methylbutanoic acid, 2-methylpentanoic acid.

[0019] According to an embodiment of the present application, when the aliphatic carboxylic acid having 5 to 7 carbon atoms is selected from two or more of the above-mentioned aliphatic carboxylic acids, the mass ratio thereof to n-butyric acid is calculated based on the total mass of the aliphatic carboxylic acids having 5 to 7 carbon atoms.

[0020] According to an embodiment of the present application, the sum of the weight percentages of the polyol ester base oil A and the polyalkylene glycol base oil B is calculated as 100%, comprising 10 to 50% of the polyol ester base oil A and 50 to 90% of the polyalkylene glycol base oil B;

[0021] For example, the weight percentage of the polyol ester base oil A is 10%, 20%, 30%, 40%, 50%;

[0022] For example, the weight percentage of the polyalkylene glycol base oil B is 50%, 60%, 70%, 80%, 90%.

[0023] According to an embodiment of the present application, the polyol ester base oil A is a polyol ester formed from a polyol and a mixed fatty acid, the polyol is mono- and di-pentaerythritol at a molar ratio of 1 :5, and the mixed fatty acid is n-butyric acid, 2-ethylhexanoic acid and n-pentanoic acid at a mass ratio of 45:35:20.

[0024] According to an embodiment of the present application, the polyol ester base oil A is a polyol ester formed from a polyol and a mixed fatty acid, the polyol is mono- and di-pentaerythritol at a molar ratio of 1 :8, and the mixed fatty acid is n-butyric acid, 2-ethylhexanoic acid and n-pentanoic acid at a mass ratio of 42:38:20.

[0025] According to an embodiment of the present application, the polyol ester base oil A is a polyol ester formed from a polyol and a mixed fatty acid, the polyol is monopentaerythritol and dipentaerythritol in a molar ratio of 1:10, and the mixed fatty acid is n-butyric acid, 2-ethylhexanoic acid, and 2-methylbutyric acid in a mass ratio of 35:40:25.

[0026] According to an embodiment of the present application, the polyol ester base oil A is a polyol ester formed from a polyol and a mixed fatty acid, the polyol is monopentaerythritol and dipentaerythritol in a molar ratio of 1:8, and the mixed fatty acid is n-butyric acid, 3-ethylhexanoic acid, and 3-methylbutyric acid in a mass ratio of 25:45:30.

[0027] According to an embodiment of the present application, the polyol ester base oil A is a polyol ester formed from a polyol and a mixed fatty acid, the polyol is monopentaerythritol and dipentaerythritol in a molar ratio of 1:7, and the mixed fatty acid is n-butyric acid, 2-ethylhexanoic acid, and 2-methylpentanoic acid in a mass ratio of 23:49:28.

[0028] According to an embodiment of the present application, the polyol ester base oil A is a polyol ester formed from a polyol and a mixed fatty acid, the polyol is monopentaerythritol and dipentaerythritol in a molar ratio of 1:9, and the mixed fatty acid is n-butyric acid, 2-ethylhexanoic acid, and 2-methylpentanoic acid in a mass ratio of 22:50:28.

[0029] According to an embodiment of the present application, the polyol ester base oil A is a polyol ester formed from a polyol and a mixed fatty acid, the polyol is monopentaerythritol and dipentaerythritol in a molar ratio of 1:8, and the mixed fatty acid is n-butyric acid, 2-ethylhexanoic acid, and n-pentanoic acid in a mass ratio of 20:53:27.

[0030] According to an embodiment of the present application, the weight ratio of the polyol and the mixed fatty acid is 1:(0.5-5), for example, 4:6.

[0031] According to an embodiment of the present application, the m is 15, 15.5, 16, 16.5, 17, 17.1, 18, 19, 19.5, 20, 21, 21.8, 22, or a number between any two of them.

[0032] According to an embodiment of the present application, the alkyl group of 1-5 carbon atoms can be methyl, ethyl, propyl, isopropyl, butyl, isobutyl, or pentyl.

[0033] According to embodiments of the present application, the refrigerant oil further contains an acid scavenger, which includes, but is not limited to, a carbodiimide compound, for example, at least one selected from the group consisting of a dialkyl carbodiimide, a diphenyl carbodiimide, a bis(alkylphenyl)carbodiimide, a diisopropyl carbodiimide, a dicyclohexyl carbodiimide, a ditolyl carbodiimide, a bis(isopropylphenyl)carbodiimide, a bis(diisopropylphenyl)carbodiimide, a bis(triisopropylphenyl)carbodiimide, a bis(butylphenyl)carbodiimide, a bis(dibutylphenyl)carbodiimide, or a bis(nonylphenyl)carbodiimide, and the like.

[0034] According to embodiments of the present application, the refrigerant oil further contains an anti-wear agent. For example, the anti-wear agent includes, but is not limited to, at least one selected from the group consisting of a phosphate ester, a thiophosphate ester, a zinc dialkyldithiophosphate, a triphenyl phosphate (TPP), a tricresyl phosphate (TCP), or a triphenyl thiophosphate (TPPT), and the like.

[0035] According to embodiments of the present application, the refrigerant oil further contains an antioxidant, which includes, but is not limited to, di-tert-butyl-p-cresol and / or an alkyl diphenyl amine.

[0036] The present application also provides a fluid composition comprising the refrigerant oil composition described above and a refrigerant.

[0037] According to embodiments of the present application, the refrigerant is selected from the group consisting of an alkane-based refrigerant, for example, an R290 refrigerant (propane refrigerant).

[0038] According to embodiments of the present application, when the content of the refrigerant oil composition in the fluid composition is 20 wt%, the two-phase separation temperature of the polyol ester composition and the R290 refrigerant is -25°C to 20°C.

[0039] According to embodiments of the present application, the total acidity (TAN) of the refrigerant oil composition is less than 0.1 mgKOH / g, preferably less than 0.01 mgKOH / g.

[0040] According to embodiments of the present application, the polyol ester base oil A is prepared by the following method:

[0041] The method includes reacting a mono-pentaerythritol, a di-pentaerythritol, and a fatty acid mixture to obtain the polyol ester base oil A.

[0042] According to embodiments of the present application, the mono-pentaerythritol and the di-pentaerythritol have the molar ratio as shown above.

[0043] According to embodiments of the present application, the fatty acid mixture has the meaning as shown above.

[0044] According to the embodiment of the present application, the weight ratio of the sum of the weight of the mono- and di-pentaerythritol to the weight of the fatty acid mixture is 1:(0.5-5), for example 4:6;

[0045] According to the embodiment of the present application, the reaction can be carried out in the presence of a catalyst;

[0046] According to the embodiment of the present application, the reaction is an esterification reaction;

[0047] According to the embodiment of the present application, the method further comprises post-treatment of the reaction product. The post-treatment includes but is not limited to pH adjustment, water washing and / or dehydration of the reaction product, etc. Alternatively, the reaction product can also be decolorized by using an adsorbent;

[0048] According to the embodiment of the present application, the pH adjustment can be achieved by adding a base, for example, sodium hydroxide can be used to neutralize the excess acid added in the reaction;

[0049] According to the embodiment of the present application, the dehydration can be carried out under reduced pressure; it can also be carried out under heating, and the heating temperature is 60-110°C;

[0050] According to the embodiment of the present application, the temperature of the reaction can be 150-250°C, and the reaction time can be 6-24h;

[0051] According to the embodiment of the present application, the adsorbent is selected from at least one of activated clay, carbon black, and activated carbon;

[0052] According to the embodiment of the present application, the catalyst can be selected from the esterification catalysts known in the art, for example, at least one selected from tin (II) oxalate, tin (II) oxide, tetra-n-butyl titanate, tetraisopropyl titanate, and methane sulfonic acid;

[0053] According to the embodiment of the present application, the catalyst is 0.05-0.5% of the total mass of the mixed fatty acid.

[0054] According to the embodiment of the present application, the polyalkyloxy ether base oil B is prepared by the following method:

[0055] The polyalkyloxy ether base oil B is prepared by polymerization of propylene oxide in the presence of a starter and a catalyst;

[0056] According to the embodiment of the present application, the polymerization is carried out under an inert atmosphere, for example, under nitrogen atmosphere;

[0057] According to the embodiment of the present application, the temperature of the polymerization is above 80°C, for example, 100-150°C, such as 110-120°C;

[0058] According to the embodiment of the present application, the starting agent can be selected from at least one of ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, n-butanol, etc.; as an example, the starting agent can be selected from at least one of ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol;

[0059] According to the embodiment of the present application, the catalyst can be selected from at least one of hydroxides of alkali metals or compounds in which the hydrogen of alcohol hydroxyl is replaced by alkali metals, such as at least one of sodium hydroxide, potassium hydroxide, sodium methoxide, potassium methoxide, sodium ethoxide, potassium ethoxide;

[0060] According to the embodiment of the present application, the preparation method further comprises purifying the crude product obtained from the polymerization reaction; preferably, the purification comprises adding water, phosphoric acid and magnesium silicate polyether refining agent, and dehydration and filtration steps;

[0061] As an example, deionized water of 1-5wt% of the mass of the crude product, 0.15-0.45wt% of phosphoric acid, and 0.03-0.1wt% of magnesium silicate polyether refining agent are added;

[0062] According to the embodiment of the present application, after the addition of water, phosphoric acid and magnesium silicate polyether refining agent, the obtained mixture is stirred at 75-95℃ for 1-2h, then vacuum dehydrated to moisture below 0.01%, and then subjected to circulating filtration to obtain the polyalkoxy ether base oil B.

[0063] The present application also provides a preparation method of the above-mentioned refrigeration oil composition:

[0064] The above-mentioned polyol ester base oil A and polyalkoxy ether base oil B are mixed and stirred uniformly to obtain the refrigeration oil composition.

[0065] According to the embodiment of the present application, the polyol ester base oil A and polyalkoxy ether base oil B can be mixed in a certain weight percentage, such as 10:90, 20:80, 30:70, 40:60, 50:50.

[0066] The present application also provides the use of the refrigeration oil composition or fluid composition in a compression refrigeration, air conditioning or heat pump system.

[0067] Advantages:

[0068] The refrigerant oil composition of the present application adopts a polyol ester base oil of pentaerythritol and di-pentaerythritol with short-chain acid structures of n-butyric acid, 2-ethylhexanoic acid, and short-chain aliphatic carboxylic acids with carbon atom numbers of 5-7, and a base oil of a polyalkoxy ether base oil with two components, by changing the ratio (or polymerization degree) and proportion of the two components, the two-phase separation temperature of the refrigerant oil composition and R290 refrigerant can be regulated, thereby achieving the application requirement of significantly improving the compatibility with R290 refrigerant, and the composition has good hydrolysis stability. DETAILED DESCRIPTION

[0069] The technical solutions of the present application will be further described in detail below in combination with specific embodiments. It should be understood that the following embodiments are only exemplary to illustrate and explain the present application, and should not be interpreted as limiting the scope of protection of the present application. Any technical solutions achieved, modified or adjusted based on the above description of the present application are all included in the scope of protection intended by the present application.

[0070] Unless otherwise specified, the raw materials and reagents used in the following examples are commercially available or can be prepared by known methods.

[0071] In order to ensure that the refrigerant oil composition has good viscosity-temperature performance and thermal stability, when polyol ester base oil A and polyalkoxy ether base oil B are blended, the 40℃ kinematic viscosity of each component needs to be tested first, preferably the 40℃ kinematic viscosity of A and B two components is within ±20%, more preferably the 40℃ kinematic viscosity of the two components is within ±10%, further preferably the 40℃ kinematic viscosity of the two components is within ±5%.

[0072] The difference ratio of the kinematic viscosity of compound A and compound B is calculated by formula (1):

[0073] The difference ratio=(kinematic viscosity of compound A-kinematic viscosity of compound B) / kinematic viscosity of compound B x 100%.

[0074] Example 1

[0075] Preparation method of polyol ester base oil A:

[0076] A reaction mixture was obtained by mixing 40 wt% of a polyol (monopentaerythritol and dipentaerythritol in a molar ratio of 1:5) and 60 wt% of a mixed fatty acid (n-butyric acid, 2-ethylhexanoic acid, and n-valeric acid in a mass ratio of 45:35:20) and stirring them well, and a tin (II) oxalate catalyst was added in an amount of 0.3% of the total mass of the mixed fatty acid. The reaction was started at 160°C and gradually increased to 230°C, and the reaction was continued until no more water was produced. The reaction time was 20 hours. After the reaction mixture was cooled to 70°C, 0.5 wt% of a sodium hydroxide aqueous solution (30 wt%) was added with respect to the total amount of the reaction mixture, and stirred at 70°C for 15 minutes. After standing for 60 minutes, the water layer separated from the mixture was removed. Thereafter, 5 wt% of water was added with respect to the total amount of the reaction mixture, and stirred at 70°C for 15 minutes. After standing for 60 minutes, the water layer separated from the mixture was removed. This operation was repeated twice. Then, 3 wt% of activated clay and 3 wt% of activated carbon were added with respect to the mass of the polyol ester obtained, and dehydrated at 100°C while stirring. Finally, the adsorbents were removed by filtration, thereby obtaining a polyol ester base oil A.

[0077] Method for preparing a polyalkyloxyether base oil B:

[0078] A reaction vessel was charged with 6 wt% of propylene glycol and 0.2 wt% of a potassium hydroxide catalyst, and then subjected to nitrogen replacement three times. The vessel was vacuumed to 0.06 MPa, and then heated to 110°C. Thereafter, 94 wt% of propylene oxide was continuously introduced while controlling the reaction temperature to be not higher than 120°C. After the completion of the introduction of the propylene oxide, the reaction was aged for 0.5 hours, and then vacuumed for 10 minutes. The crude ether was obtained by cooling and discharging the reaction mixture. Thereafter, 0.1 wt% of deionized water, 0.03 wt% of phosphoric acid, and 0.03 wt% of a magnesium silicate polyether refining agent were added to the crude ether, and then stirred at 90°C for 1 hour. The ether was dehydrated by vacuuming until the water content was less than 0.01%. Finally, the polyalkyloxyether base oil B was obtained by performing a cycle filtration.

[0079] The average molar addition number m of the propylene oxide in the polyalkyloxyether base oil B was 21.8.

[0080] Preparation of a refrigerator oil composition:

[0081] The polyol ester base oil A and the polyalkyloxyether base oil B were mixed in a weight ratio of 10:90, 20:80, 30:70, 40:60, and 50:50, respectively, and then stirred to obtain a refrigerator oil composition.

[0082] Example 2

[0083] Method for preparing a polyol ester base oil A:

[0084] A reaction mixture was obtained by mixing 40 wt% of a polyol (monopentaerythritol and dipentaerythritol in a molar ratio of 1:8) and 60 wt% of a mixed fatty acid (n-butyric acid, 2-ethylhexanoic acid, and n-valeric acid in a mass ratio of 42:38:20) and stirring them well, and a tin (II) oxide catalyst was added in an amount of 0.3% based on the total mass of the mixed fatty acid. The reaction was started at 160°C and gradually increased to 230°C, and the reaction was continued until no more water was produced. The reaction time was 20 hours. After the reaction mixture was cooled to 70°C, 0.5 wt% of a sodium hydroxide aqueous solution (30 wt%) was added based on the total amount of the reaction mixture, and stirred at 70°C for 15 minutes. After standing for 60 minutes, the separated water layer was removed. Subsequently, 5 wt% of water was added based on the total amount of the reaction mixture, and stirred at 70°C for 15 minutes. After standing for 60 minutes, the separated water layer was removed. This operation was repeated twice. Then, 3 wt% of activated clay and 3 wt% of activated carbon were added based on the mass of the obtained polyol ester, and dehydrated by stirring at 100°C. Finally, the adsorbents were removed by filtration, thereby obtaining a polyol ester base oil A.

[0085] Method for preparing a polyalkyloxyether base oil B:

[0086] A reaction vessel was charged with 7 wt% of propylene glycol and 0.02 wt% of a potassium hydroxide catalyst, and then replaced with nitrogen three times. The vessel was vacuumed to 0.06 MPa, and then heated to 110°C. Then, 93 wt% of propylene oxide was continuously introduced while controlling the reaction temperature to be not higher than 120°C. After the feeding was completed, the reaction was aged for 0.5 hours, and then vacuumed for 10 minutes. The crude ether was obtained by cooling and discharging. Then, 0.1 wt% of deionized water, 0.03 wt% of phosphoric acid, and 0.03 wt% of a magnesium silicate polyether refining agent were added to the crude ether, and stirred at 90°C for 1 hour. Then, the ether was dehydrated under vacuum until the water content was less than 0.01%. Finally, the ether was subjected to a circulation filtration, thereby obtaining a polyalkyloxyether base oil B.

[0087] The average molar addition number m of propylene oxide of the obtained polyalkyloxyether base oil B was 19.5.

[0088] Preparation of a refrigerator oil composition:

[0089] The polyol ester base oil A and the polyalkyloxyether base oil B were mixed at a weight ratio of 10:90, 20:80, 30:70, 40:60, and 50:50, respectively, and then stirred to obtain a refrigerator oil composition.

[0090] Example 3

[0091] Method for preparing a polyol ester base oil A:

[0092] A reaction mixture was obtained by mixing 40 wt% of a polyol (monopentaerythritol and dipentaerythritol in a molar ratio of 1:10) and 60 wt% of a mixed fatty acid (n-butyric acid, 2-ethylhexanoic acid, and 2-methylbutyric acid in a mass ratio of 35:40:25) and stirring them well, and a tin (II) oxide catalyst was added in an amount of 0.3% based on the total mass of the fatty acid. The reaction was started at 160°C and gradually increased to 230°C, and the reaction was continued until no more water was produced. The reaction time was 20 hours. After the reaction mixture was cooled to 70°C, 0.5 wt% of a sodium hydroxide aqueous solution (30 wt%) was added based on the total amount of the reaction mixture, and stirred at 70°C for 15 minutes. After standing for 60 minutes, the water layer separated from the mixture was removed. Subsequently, 5 wt% of water was added based on the total amount of the reaction mixture, and stirred at 70°C for 15 minutes. After standing for 60 minutes, the water layer separated from the mixture was removed. This operation was repeated twice. Then, 3 wt% of activated clay and 3 wt% of activated carbon were added based on the mass of the polyol ester obtained, and dehydrated by stirring at 100°C. Finally, the adsorbents were removed by filtration, thereby obtaining a polyol ester base oil A.

[0093] Method for preparing a polyalkyloxyether base oil B:

[0094] A reaction vessel was charged with 7.5 wt% of propylene glycol and 0.02 wt% of a potassium hydroxide catalyst, and then replaced with nitrogen three times. The vessel was vacuumed to 0.06 MPa, and then heated to 110°C. 92.5 wt% of propylene oxide was continuously introduced while controlling the reaction temperature to be not more than 120°C. After the completion of the feeding, the reaction was aged for 0.5 hours, and then vacuumed for 10 minutes. The crude ether was obtained by cooling and discharging the reaction mixture. Then, 0.1 wt% of deionized water, 0.03 wt% of phosphoric acid, and 0.03 wt% of a magnesium silicate polyether refining agent were added to the crude ether, and stirred at 90°C for 1 hour. The mixture was vacuum-dehydrated until the water content was less than 0.01%, and then subjected to a cycle of filtration, thereby obtaining a polyalkyloxyether base oil B.

[0095] The average molar addition number m of propylene oxide of the polyalkyloxyether base oil B obtained was 17.1.

[0096] Preparation of a refrigerator oil composition:

[0097] The polyol ester base oil A and the polyalkyloxyether base oil B were mixed in a weight ratio of 10:90, 20:80, 30:70, 40:60, and 50:50, respectively, and then stirred to obtain a refrigerator oil composition.

[0098] Example 4

[0099] Method for preparing a polyol ester base oil A:

[0100] A reaction mixture was obtained by mixing 40 wt% of a polyol (monopentaerythritol and dipentaerythritol in a molar ratio of 1:8) and 60 wt% of a mixed fatty acid (n-butyric acid, 3-ethylhexanoic acid, and 3-methylbutyric acid in a mass ratio of 25:45:30) and stirring them well, and a tin (II) oxide catalyst was added in an amount of 0.3% based on the total mass of the fatty acid. The reaction was started at 160°C and gradually increased to 230°C, and the reaction was continued until no more water was produced. The reaction time was 20 hours. After the reaction mixture was cooled to 70°C, 0.5 wt% of a sodium hydroxide aqueous solution (30 wt%) was added based on the total amount of the reaction mixture, and stirred at 70°C for 15 minutes. After standing for 60 minutes, the water layer separated from the mixture was removed. Subsequently, 5 wt% of water was added based on the total amount of the reaction mixture, and stirred at 70°C for 15 minutes. After standing for 60 minutes, the water layer separated from the mixture was removed. This operation was repeated twice. Then, 3 wt% of activated clay and 3 wt% of activated carbon were added based on the mass of the polyol ester obtained, and the mixture was stirred at 100°C to remove water. Finally, the adsorbents were removed by filtration, thereby obtaining a polyol ester base oil A.

[0101] Method for preparing a polyalkyloxyether base oil B:

[0102] A reaction vessel was charged with 8 wt% of propylene glycol and 0.02 wt% of a potassium hydroxide catalyst, and then subjected to nitrogen replacement three times. The vessel was vacuumed to 0.06 MPa, and then heated to 110°C. Then, 92 wt% of propylene oxide was continuously introduced while the reaction temperature was controlled to be not higher than 120°C. After the feeding was completed, the reaction was aged for 0.5 hour, and then vacuumed for 10 minutes. The crude ether was obtained by cooling and discharging the reaction mixture. Then, 0.1 wt% of deionized water, 0.03 wt% of phosphoric acid, and 0.03 wt% of a magnesium silicate polyether refining agent were added to the crude ether, and then stirred at 90°C for 1 hour. Then, the mixture was vacuumed to remove water until the water content was less than 0.01%. Finally, the polyalkyloxyether base oil B was obtained by performing a cycle filtration.

[0103] The average molar addition number m of propylene oxide of the polyalkyloxyether base oil B obtained was 16.5.

[0104] Preparation of a refrigerator oil composition:

[0105] The polyol ester base oil A and the polyalkyloxyether base oil B were mixed in a weight ratio of 10:90, 20:80, 30:70, 40:60, and 50:50, respectively, and then stirred to obtain a refrigerator oil composition.

[0106] Example 5

[0107] Method for preparing a polyol ester base oil A:

[0108] A reaction mixture was obtained by mixing 40 wt% of a polyol (monopentaerythritol and dipentaerythritol in a molar ratio of 1:7) and 60 wt% of a mixed fatty acid (n-butyric acid, 2-ethylhexanoic acid, and 2-methylvaleric acid in a mass ratio of 23:49:28) and stirring them well, and the reaction was carried out at a temperature gradually increased from 160°C to 230°C until no water was produced, using titanium tetraisopropoxide as a catalyst added in an amount of 0.3% of the total mass of the fatty acid, for 20 hours. After the reaction mixture was cooled to 70°C, 0.5 wt% of an aqueous sodium hydroxide solution (30 wt%) was added to the reaction mixture, and the mixture was stirred at 70°C for 15 minutes. After the mixture was left to stand for 60 minutes, the water layer separated from the mixture was removed. Subsequently, 5 wt% of water was added to the reaction mixture, and the mixture was stirred at 70°C for 15 minutes. After the mixture was left to stand for 60 minutes, the water layer separated from the mixture was removed. This operation was repeated twice. Then, 3 wt% of activated clay and 3 wt% of activated carbon were added to the obtained mixture, and the mixture was stirred at 100°C to remove water. Finally, the adsorbents were removed by filtration, thereby obtaining a polyol ester base oil A.

[0109] Method for preparing a polyalkyloxyether base oil B:

[0110] A reaction vessel was first charged with 9 wt% of propylene glycol and 0.02 wt% of a potassium hydroxide catalyst, and the vessel was replaced with nitrogen three times and vacuumed to 0.06 MPa. The temperature was increased to 110°C, and 92 wt% of propylene oxide was continuously introduced while the temperature was controlled to be not higher than 120°C. After the introduction of the propylene oxide was completed, the mixture was aged for 0.5 hours, vacuumed for 10 minutes, and discharged after being cooled. Then, 0.1 wt% of deionized water, 0.03 wt% of phosphoric acid, and 0.03 wt% of a magnesium silicate polyether refining agent were added to the obtained crude ether, and the mixture was stirred at 90°C for 1 hour. Then, the mixture was vacuum-dried until the water content was less than 0.01%, and was subjected to a cycle of filtration, thereby obtaining a polyalkyloxyether base oil B.

[0111] The average number of moles of propylene oxide added to the polyalkyloxyether base oil B was 15.5.

[0112] Preparation of a refrigerator oil composition:

[0113] The polyol ester base oil A and the polyalkyloxyether base oil B were mixed at a weight ratio of 10:90, 20:80, 30:70, 40:60, and 50:50, respectively, and were stirred to be uniform, thereby obtaining a refrigerator oil composition.

[0114] Example 6

[0115] Method for preparing a polyol ester base oil A:

[0116] A polyol ester base oil A was prepared in the following manner. 40 wt% of a polyol (monopentaerythritol and dipentaerythritol at a molar ratio of 1:9) and 60 wt% of a mixed fatty acid (n-butyric acid, 2-ethylhexanoic acid, and 2-methylvaleric acid at a mass ratio of 22:50:28) were thoroughly mixed, a catalyst was methane sulfonic acid, and the amount of addition was 0.3% of the total mass of the fatty acid. The reaction was started at 160°C, and the temperature was gradually increased to 230°C, and the reaction was continued until no more water was produced. The reaction time was 20 hours. After the reaction mixture was cooled to 70°C, 0.5% by mass of an aqueous sodium hydroxide solution (30 wt%) was added with respect to the total amount of the reaction liquid, and the mixture was stirred at 70°C for 15 minutes. After the mixture was left to stand for 60 minutes, the water layer separated from the mixture was removed. Thereafter, 5 wt% of water was added with respect to the total amount of the reaction liquid, and the mixture was stirred at 70°C for 15 minutes. After the mixture was left to stand for 60 minutes, the water layer separated from the mixture was removed. This operation was repeated twice. Subsequently, 3 wt% of activated clay and 3 wt% of activated carbon were added with respect to the mass of the obtained polyol ester, and the mixture was stirred at 100°C to remove water. Finally, the adsorbents were removed by filtration, and a polyol ester base oil A was obtained.

[0117] The polyalkyloxy ether base oil B was prepared in the following manner. The same procedure as in Example 3, Component B, was used.

[0118] The average number of molar additions of propylene oxide, m, of the polyalkyloxy ether base oil B prepared was 17.1.

[0119] Preparation of a refrigerator oil composition:

[0120] The polyol ester base oil A and the polyalkyloxy ether base oil B were mixed at a weight ratio of 10:90, 20:80, 30:70, 40:60, and 50:50, respectively, and the mixture was stirred until it was uniform. A refrigerator oil composition was obtained.

[0121] Example 7

[0122] Preparation of a polyol ester base oil A:

[0123] A mixture of 40 wt% of a polyol (monopentaerythritol and dipentaerythritol at a molar ratio of 1:8) and 60 wt% of a mixed fatty acid (n-butyric acid, 2- ethylhexanoic acid and n-valeric acid at a mass ratio of 20:53:27) was mixed well, and a catalyst of tin (II) oxalate was added at 0.3% of the total mass of the fatty acid. The reaction was started at 160°C and gradually increased to 230°C, and the reaction was continued until no more water was produced. The reaction time was 20 hours. After the reaction mixture was cooled to 70°C, 0.5 wt% of an aqueous sodium hydroxide solution (30 wt%) was added with respect to the total amount of the reaction liquid, and stirred at 70°C for 15 minutes. After standing for 60 minutes, the water layer separated from the mixture was removed. Thereafter, 5 wt% of water was added with respect to the total amount of the reaction liquid, and stirred at 70°C for 15 minutes. After standing for 60 minutes, the water layer separated from the mixture was removed. This operation was repeated twice. Then, 3 wt% of activated clay and 3 wt% of activated carbon were added with respect to the mass of the obtained polyol ester, and dehydrated by stirring at 100°C. Finally, the adsorbents were removed by filtration, thereby obtaining a polyol ester base oil A.

[0124] Method for producing a polyalkyloxyether base oil B: same as Component B of Example 3,

[0125] The average molar addition number m of propylene oxide of the produced polyalkyloxyether base oil B was 17.1.

[0126] Production of a refrigerator oil composition:

[0127] The polyol ester base oil A and the polyalkyloxyether base oil B described above were mixed at 10:90, 20:80, 30:70, 40:60 and 50:50 by weight, respectively, and stirred uniformly, and finally a refrigerator oil composition was obtained.

[0128] Comparative Example 1: polyol ester base oil A of Example 1;

[0129] Comparative Example 2: polyol ester base oil A of Example 3;

[0130] Comparative Example 3: polyalkyloxyether base oil B of Example 3;

[0131] Comparative Example 4:

[0132] Component A: Method for producing a polyol ester base oil A as follows:

[0133] A reaction mixture was obtained by mixing 40 wt% of a polyol (monopentaerythritol and dipentaerythritol at a molar ratio of 1:8) and 60 wt% of a mixed fatty acid (n-butyric acid and 2-ethylhexanoic acid at a mass ratio of 35:65) and stirring them well, and the reaction was carried out at a temperature rising from 160°C to 230°C with a tin (II) oxalate catalyst added at 0.3% of the total mass of the fatty acid, for 20 hours until no more water was produced. After the reaction mixture was cooled to 70°C, 0.5 wt% of a 30 wt% aqueous sodium hydroxide solution was added, and the mixture was stirred at 70°C for 15 minutes. After the mixture was left to stand for 60 minutes, the water layer separated from the mixture was removed. Subsequently, 5 wt% of water was added to the mixture, and the mixture was stirred at 70°C for 15 minutes. After the mixture was left to stand for 60 minutes, the water layer separated from the mixture was removed. This operation was repeated twice. Then, 3 wt% of activated clay and 3 wt% of activated carbon were added to the resulting polyol ester, and the mixture was stirred at 100°C to remove water. Finally, the adsorbents were removed by filtration, thereby obtaining a polyol ester base oil A.

[0134] Component B: polyalkylene glycol base oil B of Example 3;

[0135] The polyol ester base oil A and the polyalkylene glycol base oil B were mixed at a weight ratio of 20:80 and stirred well, thereby obtaining a refrigerator oil composition.

[0136] Comparative Example 5

[0137] Component A: the same as the polyol ester base oil A of Example 1;

[0138] Component B: the polyalkylene glycol base oil B was prepared as follows:

[0139] First, 10 wt% of propylene glycol and 0.02 wt% of a potassium hydroxide catalyst were sequentially added to a reaction kettle, and the kettle was replaced with nitrogen three times, vacuumed to 0.08 MPa, and heated to 120°C. Then, 90 wt% of propylene oxide was continuously introduced into the kettle while the temperature was controlled at 120°C. After the feeding was completed, the kettle was aged for 1 hour, vacuumed for 10 minutes, and cooled to discharge the product. Then, 0.1 wt% of deionized water, 0.03 wt% of phosphoric acid, and 0.01 wt% of a magnesium silicate polyether refining agent were added to the product, and the mixture was stirred at 85°C for 1.5 hours. Then, the mixture was vacuum-dried until the water content was less than 0.01%, and then subjected to a cycle of filtration, thereby obtaining a polyalkylene glycol base oil B. The average number of propylene oxide moles added to the polyalkylene glycol base oil B was 11.5.

[0140] The polyol ester base oil A and the polyalkylene glycol base oil B were mixed at a weight ratio of 10:90 and stirred well, thereby obtaining a refrigerator oil composition.

[0141] Comparative Example 6

[0142] Component A: The same as the polyol ester base oil A of Example 4;

[0143] Component B: The same as the polyalkylene glycol ether base oil B of Example 4;

[0144] The above polyol ester base oil A and polyalkylene glycol ether base oil B were mixed at a weight ratio of 90:10 and stirred to homogeneity, and a refrigerant oil composition was finally obtained.

[0145] Comparative Example 7

[0146] Component A: The polyol ester base oil A was prepared as follows:

[0147] A mixture of 40 wt% of a polyol (monopentaerythritol and dipentaerythritol at a molar ratio of 2:1) and 60 wt% of a mixed fatty acid (n-butyric acid, 2-ethylhexanoic acid, and 2-methylvaleric acid at a mass ratio of 22:50:28) was mixed well, and a catalyst of tin (II) oxide was added at a rate of 0.3% of the total mass of the fatty acid. The reaction was started at 160°C and gradually increased to 230°C, and the reaction was continued until no more water was produced. The reaction time was 20 h. After the reaction mixture was cooled to 70°C, 0.5 wt% of an aqueous sodium hydroxide solution (30 wt%) was added with respect to the total amount of the reaction liquid, and stirred at 70°C for 15 min. After standing for 60 min, the water layer separated from the mixture was removed. Subsequently, 5 wt% of water was added with respect to the total amount of the reaction liquid, and stirred at 70°C for 15 min. After standing for 60 min, the water layer separated from the mixture was removed, and this operation was repeated twice. Then, 3 wt% of activated clay and 3 wt% of activated carbon were added with respect to the mass of the obtained polyol ester, and stirred at 100°C to remove water. Finally, the adsorbents were removed by filtration, and the polyol ester base oil A was obtained.

[0148] Component B: The polyalkylene glycol ether base oil B of Example 3;

[0149] The above polyol ester base oil A and polyalkylene glycol ether base oil B were mixed at a weight ratio of 20:80 and stirred to homogeneity, and a refrigerant oil composition was finally obtained.

[0150] Comparative Example 8

[0151] Component A: The polyol ester base oil A was prepared as follows:

[0152] A polyol ester base oil A was obtained by mixing 40 wt% of a polyol (monopentaerythritol and dipentaerythritol at a molar ratio of 1:8) and 60 wt% of 2-ethylhexanoic acid, and then adding a catalyst of tin (II) oxalate at an amount of 0.3% of the total mass of the fatty acid, and then performing a reaction from 200°C to 230°C for 20 hours. After the reaction mixture was cooled to 70°C, 0.5 wt% of an aqueous sodium hydroxide solution (30 wt%) was added with respect to the total amount of the reaction mixture, and then stirred at 70°C for 15 minutes. After standing for 60 minutes, the water layer separated from the mixture was removed. Thereafter, 5 wt% of water was added with respect to the total amount of the reaction mixture, and then stirred at 70°C for 15 minutes. After standing for 60 minutes, the water layer separated from the mixture was removed. This operation was repeated twice. Then, 3 wt% of activated clay and 3 wt% of activated carbon were added with respect to the mass of the obtained polyol ester, and then dehydrated by stirring at 100°C. Finally, the adsorbents were removed by filtration, thereby obtaining a polyol ester base oil A.

[0153] Component B: polyalkylene ether base oil B of Example 3;

[0154] The polyol ester base oil A and the polyalkylene ether base oil B were mixed at a weight ratio of 20:80, and then stirred to obtain a refrigerant oil composition.

[0155] Test Example 1

[0156] Test Method:

[0157] (1) Kinematic viscosity

[0158] The kinematic viscosity of each sample at 40°C was measured according to the method described in GB / T 265-1988 "Determination of kinematic viscosity of petroleum products and calculation of dynamic viscosity".

[0159] (2) Compatibility

[0160] The test was performed according to the method described in SH / T 0699-2000 "Test method for compatibility of refrigerant oil with refrigerant", and the two-phase separation temperature at a refrigerant oil composition sample content of 20 wt% (based on the sum of the mass of the refrigerant oil composition and R290 refrigerant) was used to characterize the compatibility (also known as miscibility).

[0161] (3) Stability

[0162] Chemical stability: The test was performed according to the method for testing the chemical stability of a refrigerant oil composition in a refrigeration system described in SH / T 0698-2000.

[0163] Hydrolytic stability: According to SH / T 0698-2000, a beaker containing a sample of the refrigeration oil composition is added with steel, copper and aluminum metal test rod materials as catalysts and 2000 ppm of moisture, then the beaker is placed in a pressure-resistant stainless steel autoclave, and a certain amount of R290 refrigerant is injected after the autoclave is closed. Then the sealed stainless steel autoclave is placed in a 150°C heating oven for 14 days, and the hydrolytic stability of the refrigeration oil and the refrigerant is evaluated according to the appearance, color of the metal test rod materials and the acid value of the refrigeration oil composition after the test. The pass standard: the acid value of the oil sample after the hydrolytic stability test is not more than 0.05 mgKOH / g.

[0164] Test results:

[0165] The raw material compositions and performance test results of Examples 1-7 and Comparative Examples 1-8 of the present application are shown in Tables 1 and 2, respectively.

[0166] Table 1 Summary of specific compositions and performance test results of examples

[0167]

[0168]

[0169] Table 1 (continued) Summary of specific compositions and performance test results of examples

[0170]

[0171]

[0172]

[0173] Table 2 Summary of specific compositions and performance test results of comparative examples 1-8

[0174]

[0175] Table 2 (continued) Summary of specific compositions and performance test results of comparative examples

[0176]

[0177]

[0178] Note: "-" in the table indicates that the performance is not tested.

[0179] From Table 1, it can be seen that the refrigeration oil compositions in Examples 1-7 all have good compatibility and hydrolytic stability with R290 refrigerant.

[0180] Comparative Example 1 and 2 are polyol ester base oils synthesized by using pentaerythritol and dipentaerythritol with fatty acid mixture, although they have good mutual solubility with R290, but their two-phase separation temperatures are all below -50℃, when they are combined with refrigerant, the refrigerant will dilute the viscosity of the refrigerator oil more, the viscosity will decrease greatly, the decrease of viscosity will reduce the lubricity, causing the wear of sliding parts, so it is meaningless to continue other test items.

[0181] Comparative Example 3 is a polyalkoxy ether base oil synthesized by using propylene oxide polymerization, which is not compatible with R290 refrigerant, so it is meaningless to continue other test items.

[0182] Comparative Example 4 is a refrigerator oil composition prepared by mixing polyol ester base oil A synthesized by using pentaerythritol and dipentaerythritol with n-butyric acid and 2-ethylhexanoic acid and polyalkoxy ether base oil B, component A and B do not meet the proportion requirement, therefore, its hydrolytic stability is poor, and cannot meet the index requirements of compressor OEM manufacturers.

[0183] The value of m of component B of Comparative Example 5 does not meet the requirement of a number between 15 and 22, so that the kinematic viscosity at 40℃ of the mixed refrigerator oil composition is only 47.78mm 2 / s, which has a large difference from the commonly used 68 viscosity of OEM compressor manufacturers, which will cause insufficient lubrication performance and part wear, and cannot meet the index requirements of compressor OEM manufacturers, so it is meaningless to continue other test items.

[0184] Comparative Example 6 is the mixing ratio of component A and component B does not meet the value requirement of the mixing ratio, which will result in that the two-phase separation temperature of the final refrigerator oil composition and R290 refrigerant is below -50℃, when they are combined with refrigerant, the refrigerant will dilute the viscosity of the refrigerator oil more, the viscosity will decrease greatly, the decrease of viscosity will reduce the lubricity, causing the wear of sliding parts, so it is meaningless to continue other test items.

[0185] Comparative Example 7 is the mixing ratio of pentaerythritol and dipentaerythritol of component A does not meet the value requirement, so that the kinematic viscosity at 40℃ of the mixed refrigerator oil composition is only 32.5mm 2 / s, which has a large difference from the commonly used 68 viscosity of OEM compressor manufacturers, which will cause insufficient lubrication performance and part wear, and cannot meet the index requirements of compressor OEM manufacturers, so it is meaningless to continue other test items.

[0186] Comparative Example 8 is Component A, 2-ethylhexanoic acid, which is not a fatty carboxylic acid having 5 to 7 carbon atoms as defined in the present application, and this results in a final refrigeration oil composition having a two-phase separation temperature with R290 refrigerant of less than -50°C. When combined with the refrigerant, the refrigerant dilutes the refrigeration oil viscosity more, and the viscosity decreases more, and the decrease in viscosity results in a decrease in lubricity, which causes wear of sliding parts. Therefore, it is meaningless to continue the other test items.

[0187] The above has described the embodiments of the present application by way of example. However, the scope of the present application is not limited to the above-described embodiments. Any modification, equivalent replacement, improvement, etc. made by those skilled in the art within the spirit and principle of the present application should be included in the scope of the present application.

Claims

1. A refrigeration oil composition characterized in that, The composition comprises a polyol ester base oil A and a polyalkoxy ether base oil B; The polyol ester base oil A comprises esters formed from a mixture of mono-pentaerythritol and fatty acids and esters formed from a mixture of di-pentaerythritol and fatty acids; The fatty acid mixture comprises n-butyric acid, 2-ethylhexanoic acid and aliphatic carboxylic acids with carbon atom number of 5-7; The molar ratio of mono-pentaerythritol to di-pentaerythritol is 1:(3-20); The mass ratio of n-butyric acid to 2-ethylhexanoic acid in the fatty acid mixture is 1:(0.5-8); The mass ratio of n-butyric acid to aliphatic carboxylic acids with carbon atom number of 5-7 in the fatty acid mixture is 1:(0.2-5); The polyalkoxy ether base oil B has the following general formula: In the formula, R1 is a hydrogen atom or an alkyl group with carbon atom number of 1-5, R2 is a hydrogen atom, and m represents the average addition molar number of alkylene oxide, m is a number between 15 and 22; The total weight percentage of the polyol ester base oil A and the polyalkoxy ether base oil B is calculated according to 100%, and the polyol ester base oil A accounts for 10-50% and the polyalkoxy ether base oil B accounts for 50-90%.

2. The composition of claim 1, wherein, The molar ratio of mono-pentaerythritol to di-pentaerythritol is 1:(5-10); And / or, the mass ratio of n-butyric acid to 2-ethylhexanoic acid in the fatty acid mixture is 1:(0.5-3); And / or, the mass percentage of n-butyric acid in the fatty acid mixture is 10-60%; And / or, the mass ratio of n-butyric acid to aliphatic carboxylic acids with carbon atom number of 5-7 in the fatty acid mixture is 1:(0.4-2).

3. The composition of claim 1, wherein The aliphatic carboxylic acids with carbon atom number of 5-7 are selected from aliphatic carboxylic acids with carbon atom number of 5, 6 or 7, including isomers thereof.

4. The composition of claim 1, wherein, The aliphatic carboxylic acids with carbon atom number of 5-7 are selected from at least one of n-pentanoic acid, 2-methylbutyric acid, 3-methylbutyric acid, 2-methylpentanoic acid, 2-ethylbutyric acid, 3-methylhexanoic acid and neoheptanoic acid.

5. The composition of claim 1, wherein, The weight ratio of the sum of mono-pentaerythritol and di-pentaerythritol to the mixed fatty acid is 1:(0.5-5).

6. The composition of claim 1, wherein, The weight percentage of the polyol ester base oil A is 10%, 20%, 30%, 40%, 50%, and the weight percentage of the polyalkoxy ether base oil B is 50%, 60%, 70%, 80%, 90%.

7. The composition of claim 1, wherein, The alkyl group with carbon atom number of 1-5 is methyl, ethyl, propyl, isopropyl, butyl, isobutyl or pentyl.

8. The composition according to any one of claims 1 to 7, characterized in that, The refrigerant oil further comprises an acid scavenger, and the acid scavenger comprises a carbodiimide compound; And / or, the refrigerant oil further comprises an anti-wear agent; And / or, the refrigerant oil further comprises an antioxidant.

9. The composition of claim 1, wherein, The polyol ester base oil A is prepared by the following method: The method comprises reacting mono-pentaerythritol, di-pentaerythritol and a fatty acid mixture to obtain the polyol ester base oil A; And / or, the polyalkoxy ether base oil B is prepared by the following method: The polyalkoxy ether base oil B is prepared by polymerizing propylene oxide in the presence of a starter and a catalyst; The starter is selected from at least one of ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol and n-butanol; The catalyst is selected from at least one of hydroxides of alkali metals or compounds in which the hydrogen of alcohol hydroxyl is substituted by alkali metals.

10. A fluid composition comprising the refrigeration oil composition according to any one of claims 1 to 9 and a refrigerant.

11. The fluid composition of claim 10, wherein, The refrigerant is selected from alkane refrigerants.

12. The fluid composition of claim 10, wherein, The refrigerant is R290 refrigerant.

13. The fluid composition of claim 10, wherein, When the content of the refrigeration oil composition in the fluid composition is 20 wt%, the two-phase separation temperature of the polyol ester base oil A and the R290 refrigerant is -25°C to 20°C. And / or, the total acidity (TAN) of the refrigeration oil composition is less than 0.01 mgKOH / g.

14. A process for preparing the refrigerant oil composition according to any one of claims 1 to 9, characterized by, The preparation method comprises the following steps: Mixing the polyol ester base oil A and the polyalkoxy ether base oil B, and stirring uniformly to obtain the refrigeration oil composition.

15. Use of the refrigeration oil composition according to any one of claims 1 to 9 or the fluid composition according to any one of claims 10 to 13 in a compression refrigeration, air conditioning or heat pump system.

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