CN105331422A - High-performance refrigeration lubricating oil composition - Google Patents

Abstract

The present invention relates to a refrigerated lubricating oil composition, comprising polyol ester obtained by reacting tripentaerythritol, dipentaerythritol, pentaerythritol or a mixture thereof with one or more linear or branched saturated or unsaturated _C4-20 fatty acids products, or polyol ester products obtained by reacting tripentaerythritol with one or more linear or branched saturated or unsaturated C _4-20 fatty acids, dipentaerythritol and one or more linear or branched The polyalcohol ester products obtained by the reaction of saturated or unsaturated C _4-20 fatty acids or the polyalcohol esters obtained by the reaction of pentaerythritol and one or more linear or branched saturated or unsaturated C _4-20 fatty acids A mixture of products, the polyol ester product has the following properties: the miscible temperature with refrigerants (such as hydrofluorocarbon refrigerants, hydrofluoroolefin refrigerants, etc.) is lower than -25°C (20% of polyol esters in the refrigerant Middle), and the kinematic viscosity at 40°C is between 46 and 460cSt, and it shows a higher working viscosity after being tested under the standard conditions of the relevant compressor.

Description

High-efficiency refrigeration lubricant composition

technical field

The present invention relates to a refrigeration lubricating oil composition, which comprises tripentaerythritol (TriPE), dipentaerythritol (DiPE), pentaerythritol (PE) or a mixture thereof and one or more linear or branched saturated or unsaturated C Polyol ester (polyol-ester (POE)) obtained by the reaction of _4-20 fatty acid, or tripentaerythritol (TriPE) and one or more linear or branched saturated or unsaturated C _4-20 fatty acids The polyalcohol ester product obtained by reaction, the _polyalcohol ester product or pentaerythritol (PE ) and one or more linear or branched saturated or unsaturated C _4-20 fatty acid reaction mixture of polyol ester products, the polyol ester product (POE) has the following properties: with refrigerant (such as hydrofluorocarbon (HFC) refrigerant, hydrofluoroolefin (HFO) refrigerant, etc.), the mutual solubility temperature is lower than -25°C (20% of polyol esters in the refrigerant), and the kinematic viscosity at 40°C ( kinematicviscosity) is between 46 ~ 460cSt, and it shows a higher working viscosity after being tested under the standard conditions of the relevant compressor.

Background technique

In recent years, in response to the threat of global warming, from the Kyoto Protocol to the Copenhagen Agreement, countries have started to carry out related carbon reduction work, so carbon emission regulations have become increasingly stringent. In the refrigeration and air-conditioning industry, in addition to having to comply with the usage specifications and schedules of new environmentally friendly refrigerants, compressor factories also have an increasing demand for improving the efficiency of refrigeration systems as energy shortage issues ferment and environmental awareness rises.

Evaluating the efficiency of the refrigeration system is mainly energy efficiency ratio (COP: per 1kW of electricity, how much refrigeration capacity kW can be produced per hour). The higher the COP value, the lower the power required and the lower the operating cost for the same refrigeration capacity.

To improve the COP of refrigeration equipment, it can be improved mainly from two directions:

(1) Improve compressor design:

1. Frequency conversion operation;

2. With a suitable motor;

3. Improve the rotor tooth profile (increase the area utilization factor and reduce the leakage area);

4. Adopt high-precision processing equipment, reduce the vibration and noise of the compressor, and improve the life of the compressor;

5. Use a high-precision oil filter to control the exhaust clearance of the compressor and improve volumetric efficiency;

6. Precisely control the compression ratio, reduce improper power consumption due to insufficient compression or excessive compression;

7. Improve the oil retention efficiency of the oil separator and control the oil carryover within 2%, which can prevent excessive refrigeration oil from entering the evaporator, thereby increasing the heat transfer efficiency and improving the refrigeration capacity; and

8. Improve the pressure drop of the main components and valves of the compressor (reduce the input work required by the compressor); and

(2) Use high-efficiency refrigeration lubricants:

Refrigerated lubricating oil achieves high performance by increasing air tightness, lubricating bearings, reducing noise, taking away compression heat (cooling), reducing the friction coefficient of oil film, reducing motor power consumption and cleaning (dissolving impurities and by-products to avoid clogging).

It is more convenient and simple to improve the COP by selecting high-efficiency refrigeration lubricating oil than improving the design of the compressor, no matter in terms of cost or operation convenience.

However, the most important key to the refrigeration lubricant affecting the efficiency of the refrigeration system comes from two parts:

(1) Miscibility between the refrigeration lubricating oil and the refrigerant in the evaporator

(miscibility) and refrigerant heat transfer efficiency, and

(2) Internal lubrication and sealing effect of the compressor.

The most important consideration when choosing a refrigeration lubricating oil is its miscibility with the refrigerant, and its influence is divided into two levels: the oil return consideration of the compressor and the heat transfer efficiency of the evaporator. Although an oil separator (Oilseparator) is usually installed at the outlet of the compressor to prevent the refrigeration lubricating oil from causing too much refrigeration lubricating oil to leave the compressor with the refrigerant due to the oil carryover phenomenon (Oilcarryover), resulting in insufficient refrigeration lubricating oil inside the compressor, and then A compressor failure has occurred. However, inevitably, there will still be a small amount of refrigeration lubricating oil leaving the compressor and eventually entering the evaporator with the refrigerant. In the low-temperature environment of the evaporator, the miscibility between the refrigerant lubricating oil and the refrigerant will become poor. If phase separation occurs due to insufficient mutual solubility at this time, the refrigerant lubricating oil will accumulate on the surface of the evaporator and cannot return to the compressor. Therefore, it will not only affect the heat transfer efficiency of the refrigerant in the evaporator, but more seriously, it will lead to insufficient refrigeration lubricating oil in the compressor, resulting in compressor failure.

In addition to the above-mentioned miscibility with the refrigerant in the evaporator, the choice of refrigeration lubricating oil also needs to consider the lubricity and sealing performance of the refrigeration lubricating oil inside the compressor. However, the most important factor affecting lubricity and sealing performance is the working viscosity of the refrigeration lubricating oil under the operating conditions of the compressor.

Considering lubricity: when operating at high temperature, when the working viscosity is too low, it is easy to cause insufficient lubrication of mechanical parts during operation, resulting in increased input electrical energy and mechanical work, reducing COP; moderately increasing the working viscosity will improve the lubricity of mechanical parts , thereby increasing the COP.

Considering the sealing performance: when operating at high temperature, when the working viscosity is too low, the sealing effect of the refrigeration lubricating oil on the mechanical parts will become poor, which will easily cause leakage of the refrigerant under high temperature and high pressure operation, reduce the refrigeration capacity, and then reduce the COP; Increasing the working viscosity will improve the sealing performance of mechanical parts, which will help to improve the COP.

Considering the running resistance (Dragforce): on the premise that the viscosity is sufficient for lubrication during high temperature operation, when the working temperature decreases, the viscosity will gradually increase. If the viscosity is too high, the running resistance will increase, which will increase the input electrical energy and mechanical work Reduce COP.

The factors affecting the miscibility of refrigeration lubricants and refrigerants are mainly related to the polarity and viscosity of refrigeration lubricants. Generally speaking, the higher the viscosity of the refrigeration lubricating oil, the worse the polarity and the poorer the miscibility.

Factors affecting the working viscosity of refrigeration lubricants mainly include:

(1) the original viscosity of the refrigeration lubricant, and

(2) Viscosity Index (ViscosityIndex, VI) of refrigeration lubricating oil: the higher the viscosity index, the smaller the degree of viscosity change with temperature, and

(3) In the working environment, the ratio of the refrigerant dissolved into the refrigerated lubricating oil determines the viscosity dilution effect. When the refrigerant dissolves into the refrigeration lubricating oil in the compressor, the higher the ratio, the lower the working viscosity.

Contents of the invention

The problem to be solved by the present invention

Generally speaking, the higher the viscosity of refrigeration lubricating oil, the poorer its miscibility with refrigerant. In the present invention, by adjusting the molecular structure to change the polarity, the polyol ester product obtained by the reaction and the refrigeration lubricating oil composition containing it have the following two characteristics at the same time: excellent refrigerant miscibility, and It has a high working viscosity during operation, so as to provide sufficient lubrication protection and sufficient sealing function for mechanical parts, and at the same time, because it is fully miscible with the refrigerant, it can prevent it from being unable to return to the compressor due to phase separation in the evaporator ( Hereinafter referred to as oil return) and the problem of heat transfer reduction.

The polyol ester product (POE) of the present invention and the refrigeration lubricating oil composition containing said product need to have a high viscosity index (VI) to provide sufficient viscosity protection under high temperature operating conditions, and to provide sufficient viscosity protection under low temperature operating conditions. Under this condition, the viscosity will not increase too much and cause excessive running resistance, resulting in a decrease in COP.

In addition to the above-mentioned "working viscosity", "refrigerant miscibility" and "viscosity index", the polyol ester product (POE) and the refrigeration lubricant composition containing it of the present invention must also meet other strict requirements for refrigeration lubricants. Requirements, such as thermal oxidation stability test, hydrolytic stability, acid value, hydroxyl value, pour point, flash point, moisture and dielectric strength of sealed tubes, etc.

detailed description

In the refrigeration lubricating oil composition of the present invention, the content of polyol esters ranges from 50% to 100% by weight, preferably more than 70% by weight, more preferably more than 95% by weight.

In the polyol ester product mixture in the refrigeration lubricating oil composition of the present invention, tripentaerythritol (TriPE) reacts with one or more linear or branched saturated or unsaturated C _4-20 fatty acids. Alcohol ester product can be 0-100 weight ratio, dipentaerythritol ( _DiPE ) and the saturated or unsaturated C4-20 fatty acid reaction of one or more linear or branched polyol ester product can be 0 -100 weight ratio, the polyol ester product obtained by reacting pentaerythritol (PE) with one or more linear or branched saturated or unsaturated _C4-20 fatty acids can be 0-99 weight ratio.

In the refrigeration lubricating oil composition of the present invention, one or more additives selected from the group consisting of acid scavengers, extreme pressure additives, antioxidants or metal deactivators can be added.

The refrigeration lubricating oil composition of the present invention can be mixed with other types of synthetic refrigeration lubricating oils such as alkyl glycol compounds (PAG) and polyvinyl ether compounds (PVE). The dosage ratio of the refrigeration lubricating oil composition of the present invention to other types of refrigeration lubricating oils can be between 100:0 and 20:80, preferably 100:0 and 50:50.

The refrigeration lubricating oil composition of the present invention is suitable for the following types of refrigerants: hydrofluorocarbon (HFC) refrigerants (such as R134a, R410A, R404A, R407C), hydrofluoroolefin (HFO) refrigerants (such as R1234ze, R1234yf), especially suitable for In R134a or R410A.

The dosage ratio of the refrigeration lubricating oil composition of the present invention to the refrigerant can be in the range of 99/1-1/99, more preferably 95/5-10/90. When the amount of the refrigerant is less than the above range, it is found that the refrigerating ability is lowered, and when it is higher than the above range, the lubricating performance is lowered. The refrigeration lubricating oil composition of the present invention can be used in various refrigeration compressors.

resolve resolution

The polyol ester product (POE) of the present invention is obtained by reacting tripentaerythritol (TriPE), dipentaerythritol (DiPE), pentaerythritol (PE) or a mixture thereof with linear or branched saturated or unsaturated C _4-20 fatty acids , the polyol ester product (POE) has the following properties: the miscibility temperature with hydrofluorocarbon (HFC) refrigerant and hydrofluoroolefin (HFO) refrigerant is lower than -25°C (20% polyol ester product) , and the kinematic viscosity at 40°C is between 46 and 460cSt.

The C _4-20 fatty acid contained in the refrigeration lubricating oil composition of the present invention is preferably a C _5-10 fatty acid, such as n-pentanoic acid, n-hexanoic acid, n-heptanoic acid, n-octanoic acid, n-nonanoic acid, n-decanoic acid, 2-Methylbutanoic acid, 3-methylbutanoic acid, 2-methylhexanoic acid, 2-ethylpentanoic acid, 2-ethylhexanoic acid, 3,5,5-trimethylhexanoic acid, or neodecanoic acid Wait.

The polyol ester products of the present invention include partial esters obtained by incomplete esterification of all hydroxyl groups of polyols, or complete esters obtained by esterification of all hydroxyl groups, or partial esters and complete esters. Mixtures, but preferably fully esterified products.

The synthesis method of the polyol ester product (POE) of the present invention comprises an esterification step and a purification step.

Esterification step: an appropriate amount of one or more linear or branched saturated or unsaturated C _4-20 fatty acids in the presence of a catalyst (or no catalyst) with one, two or three selected from tripentaerythritol , dipentaerythritol or polyol reaction of pentaerythritol. Depending on the starting material and catalyst, the reaction temperature is about 150 to 250°C, preferably 180 to 240°C, more preferably 200 to 230°C, until the hydroxyl value is lower than 10mgKOH/g, preferably 5mgKOH/g g or less, more preferably 3 mgKOH/g or less.

Commonly used catalysts include stannous oxalate, stannous oxide, tetrabutyl titanate, tripropyl titanate or methanesulfonic acid.

Purification steps:

Moisture removal: Dry the system under high vacuum to remove moisture to below 50ppm.

Removal of residual acid: by adding alkali (sodium hydroxide) for neutralization and distillation, the acid value of the polyol ester product is reduced to below 0.05 mgKOH/g.

Removal of catalysts and impurities: By adding activated carbon and filter aids (perlite), catalysts and impurities can be removed by filtration.

In order to prevent the lubricating oil from being oxidized, degraded or decomposed into acid components due to the influence of heat, external air or moisture intruding into the refrigeration cycle, or residues such as rust inhibitors remaining in the refrigeration cycle, and then corroding the inside of the system, it can be used in the refrigeration system Acid scavengers are added to the oil. Suitable acid scavengers are glycidyl esters, glycidyl ethers, α-alkylene oxides, and the like. As the glycidyl ester, there may be straight-chain, branched, or cyclic saturated or unsaturated aliphatic or aromatic carboxylates having a carbon number of usually 3-30, preferably 4-24, and more preferably 6-16. acid glycidyl esters. Examples include glycidyl 2-ethylhexanoate, glycidyl 3,5,5-trimethylhexanoate, glycidyl caprate, glycidyl laurate, glycidyl tert-carboxylate, myristic acid glycidyl esters, etc. As the glycidyl ether, there may be exemplified straight-chain, branched-chain, cyclic saturated or unsaturated aliphatic or aromatic compounds with a carbon number of usually 3-30, preferably 4-24, and more preferably 6-16. glycidyl ether. Examples thereof include 2-ethylhexanoic acid glycidyl ether, isononyl glycidyl ether, decyl glycidyl ether, lauric acid glycidyl ether, and myristic acid glycidyl ether. Examples of the α-alkylene oxide include those having a carbon number of usually 4-50, preferably 4-24, more preferably 6-16. The amount of acid scavenger used is generally 0-2% by weight, preferably 0-1% by weight.

In order to prevent the wear of the metal surface of the sliding part of the compressor, improve lubricity and reduce frictional heat, extreme pressure additives can be added to the refrigeration oil as a wear modifier. Suitable additives may be phosphorus-based extreme pressure additives and sulfur-based extreme pressure additives. Phosphoric acid triesters and phosphite triesters can be used as phosphorus-based extreme pressure additives. Tricresyl phosphate, triphenyl phosphate, tris(tert-butylphenyl) phosphate, monophenylbis(tert-butylphenyl) phosphate, diphenyl(tert-butylphenyl) phosphate, etc. Tributylphenyl) ester, etc. Triethyl phosphite, tributyl phosphite, tricresyl phosphite, tris(nonylphenyl) phosphite, tris(ethylhexyl) phosphite, tris(ethylhexyl) phosphite, Decyl ester, trilauryl phosphite, etc. Examples of sulfur-based extreme pressure additives include sulfurized oils and fats, sulfurized fatty acids, sulfurized esters, sulfurized olefins, thiocarbamates, thioterpenes, dialkylthiodipropionates, and the like. The amount of extreme pressure additive is usually 0-4% by weight, preferably 0.2-2% by weight.

In order to prevent the oxidation or deterioration of lubricating oil caused by the entry of external air into the refrigeration cycle system, it is preferable to add antioxidants, such as 2,6-di-tert-butyl-4-methylphenol, 2,6-di- Phenolic antioxidants such as tributyl-4-ethylphenol, 2,2'-methylene bis(4-methyl-6-tert-butylphenol), or phenyl-α-naphthylamine, N- Amine antioxidants such as N'-diphenyl-p-phenylenediamine. The amount of antioxidant is generally 0-1% by weight, preferably 0-0.5% by weight.

In order to form an inert protective film on the metal surface or form a chelate with metal ions to inhibit the metal or its ions from catalyzing the oxidation of refrigeration oil, a metal passivator can be added to the refrigeration oil. Suitable metal deactivators are Tolutriazole derivatives (Tolutriazole), benzotriazole derivatives (Benzotriazole), thiadiazole derivatives (thiadiazde) and the like. The amount of the metal deactivator is usually 0-0.5% by weight, preferably 0-0.2% by weight.

In addition to polyol ester products (POE), polyalkylene glycol (polyalkyleneglycol (PAG), polyalkylene glycol) and polyvinyl ether (Polyvinylether (PVE)) are also often used as refrigeration lubricants. PAG is a propylene oxide (PO) and/or ethylene oxide (EO) polymer. The viscosity is controlled by the molecular weight of the polymer, and its molecular chain is controlled by the end of the molecular chain (single end or double end). Miscibility in refrigerants. PAG has good miscibility with HFC, excellent compatibility with rubber and plastic materials, and it has a very high viscosity index and excellent low temperature characteristics. PVE is a polymer with side chain ether groups. By adjusting the polymer chain length and polymer side chain carbon chain length, PVE and HFC have good miscibility, and at the same time have excellent hydrolysis resistance and excellent additive compatibility,

Analytical test method:

Stability of sealing tube thermal oxidation:

According to ANSI/ASHRAE standard 97-2007, the refrigeration lubricating oil and refrigerant are placed in a pressure-resistant glass tube with a weight ratio of 1:1, and a standard metal sheet (copper, aluminum, stainless steel) is placed and then sealed. The pressure-resistant glass tube was then placed in an oven at 175°C for 14 days. By observing the changes in the metal sheet, refrigerated lubricating oil, and refrigerant before and after heating, the stability of the refrigerated lubricating oil under thermal oxidation of the sealed tube was analyzed and compared.

Hydrolytic stability:

According to ASTMD-2619, put 75g of refrigerated lubricating oil and 25g of water into the test container, put it into the test standard copper piece, heat it at 93°C for 48 hours, observe the changes of the copper piece and refrigerated lubricating oil before and after the test, to evaluate Hydrolytic stability of refrigeration lubricants.

Kinematic viscosity and viscosity index: According to ASTM-D445, measure the kinematic viscosity at 40°C and 100°C, and calculate the viscosity index based on these two kinematic viscosities.

Density: According to ASTM-D7042, measure the density of refrigeration lubricating oil at 15°C, 40°C and 100°C.

Flash point: According to ASTM-D92, measure the open flash point value of refrigeration lubricating oil.

Pour point: According to ASTM-D97, the characteristic of low temperature pour point of refrigeration lubricating oil is measured.

Solubility of refrigerant in refrigeration oil and kinematic viscosity of the mixture: Put a predetermined amount of refrigeration lubricating oil and refrigerant into a pressure vessel at low temperature and high vacuum, heat the mixture to 100°C first, and then gradually cool down to 0°C, During the whole process of cooling, the temperature, pressure and kinematic viscosity of the mixture are monitored, and samples are taken to analyze the actual composition of the refrigerant and refrigeration lubricating oil in the mixture.

The monitoring data is calculated and drawn into the solubility curve of the mixture and the kinematic viscosity curve of the mixture. Using the solubility curve and kinematic viscosity curve, the actual kinematic viscosity of the mixture and the solubility of the refrigerant in the refrigeration oil can be calculated under specific compressor operating conditions.

Two-phase separation temperature: According to ANSI/ASHRAE standard 86-1994, a specific amount of refrigerated lubricating oil and refrigerant is sealed in a pressure-resistant glass tube, and the glass tube is placed in a low-temperature oven to gradually cool down and observe the mixture of refrigerant and refrigerated lubricating oil . When the white mist appears and finally the two phases are separated, the temperature is the two-phase separation temperature.

Dielectric Strength: According to ASTM D-877, to determine any insoluble decomposition products in the refrigeration lubricant, measure the dielectric strength during the required time interval between repeated breakdown tests.

Moisture measurement: ASTME-1064 is measured with a Karl Fischer moisture meter.

Acid value: titrated with 0.05NKOH standard test solution according to ASTM D-974.

Embodiment 1.TriPE+(iC9, MBA, nC5)

Raw material: tripentaerythritol (TriPE), and fatty acid: isoC9 (3,5,5-trimethylhexanoic acid)+MBA (2-methylbutyric acid)+nC5 (n-valeric acid) (wt%=25%: 60 %: 15%)

Additives: tricresyl phosphate 1%, 2,6-di-tert-butyl-4-methylphenol 200ppm, methyl benzotriazole derivatives 200ppm

Basic physical properties:

Example 2. Mixed ester 1

Synthetic ester 1: TriPE+neo10 (neodecanoic acid)+MBA, wherein neo10:MBA=80:20 (weight%)

Synthetic ester 2: dipentaerythritol (DiPE) + MBA

Mixed ester 1 = synthetic ester 1 (% by weight = 45%) + synthetic ester 2 (% by weight = 55%)

Additives: tricresyl phosphate 1%, 2,6-di-tert-butyl-4-methylphenol 200ppm, methyl benzotriazole derivatives 200ppm

Basic physical properties:

Example 3. Mixed esters 2

Synthetic ester 3: TriPE+iC9+MBA, wherein iC9:MBA=25:75 (weight%)

Synthetic ester 4: DiPE+MBA

Mixed ester 2 = synthetic ester 3 (% by weight = 50%) + synthetic ester 4 (% by weight = 50%)

Additives: tricresyl phosphate 1%, 2,6-di-tert-butyl-4-methylphenol 200ppm, methyl benzotriazole derivatives 200ppm

Basic physical properties:

Embodiment 4.DiPE+(nC5+iC9)

Raw material: dipentaerythritol (DiPE), and fatty acid: nC5 (n-valeric acid) + isoC9 (3,5,5-trimethylhexanoic acid) (wt% = 25%: 75%)

Additives: tricresyl phosphate 1%, 2,6-di-tert-butyl-4-methylphenol 200ppm, methyl benzotriazole derivatives 200ppm

Basic physical properties:

Embodiment 5. (TriPE+DiPE)+MBA

Raw materials: tripentaerythritol (TriPE) + dipentaerythritol (DiPE) (wt% = 57%: 43%) and fatty acid MBA (2-methylbutyric acid)

Additives: tricresyl phosphate 1%, 2,6-di-tert-butyl-4-methylphenol 200ppm, methyl benzotriazole derivatives 200ppm

Basic physical properties:

Example 6. Mixed ester 3

Synthetic ester 3: TriPE+iC9+MBA, wherein iC9:MBA=25:75 (weight%)

Synthetic ester 5: (PE+DPE)+(nC5+iC9), where

PE:DPE=92:8 (weight%)

nC5:iC9=35:65 (% by weight)

Mixed ester 3 = synthetic ester 3 (% by weight = 70%) + synthetic ester 5 (% by weight = 30%)

Additives: tricresyl phosphate 1%, 2,6-di-tert-butyl-4-methylphenol 200ppm, methyl benzotriazole derivatives 200ppm

Basic physical properties:

Embodiment 7.DiPE+(nC5+iC9)

Raw material: dipentaerythritol (DiPE), and fatty acid: nC5 (n-valeric acid) + isoC9 (3,5,5-trimethylhexanoic acid) (wt% = 55%: 45%)

Additives: tricresyl phosphate 1.5%, glycidyl tert-carbonate 0.5%, 2,6-di-tert-butyl-4-methylphenol 200ppm, methyl benzotriazole derivative 200ppm

Basic physical properties:

Embodiment 8.DiPE+(nC5+iC9)

Raw material: dipentaerythritol (DiPE), and fatty acid: nC5 (valeric acid) + isoC9 (3,5,5-trimethylhexanoic acid) (wt% = 75%: 25%)

Additives: tricresyl phosphate 1.5%, glycidyl tert-carbonate 0.5%, 2,6-di-tert-butyl-4-methylphenol 200ppm, methyl benzotriazole derivative 200ppm

Basic physical properties:

Embodiment 9.DiPE+nC5

Raw material: dipentaerythritol (DiPE), and fatty acid: nC5 (valeric acid)

Additives: tricresyl phosphate 1.5%, glycidyl tert-carbonate 0.5%, 2,6-di-tert-butyl-4-methylphenol 200ppm, methyl benzotriazole derivative 200ppm

Basic physical properties:

Comparative example 1. Lubrizol (CPI): Solest220

Basic physical properties:

Comparative example 2. Lubrizol (CPI): Solest 120

Basic physical properties:

Comparative example 3. JX Nippon Oil: Ze-Gles RB68EP

Basic physical properties:

The basic properties of the refrigeration lubricating oil of the present invention:

Moisture is the most basic requirement of refrigeration lubricants. For POE lubricating oils, the presence of high moisture can easily lead to the reverse reaction of esterification in the refrigeration system, resulting in the cracking of esters into acids, which in turn reduces the stability of refrigeration lubricating oils. Moreover, when operating at low temperature, too much water is easy to freeze, which is easy to cause system damage and reduce the heat transfer area. Examples 1 to 9 of the present invention were all treated with nitrogen to ensure that the water content met the specifications of general POE refrigeration lubricants.

The main impact of acid value on the refrigeration system mainly comes from two aspects: too high acid value is easy to accelerate the cracking reaction, and it is easy to cause corrosion of metal materials inside the system. Examples 1 to 9 of the present invention are all purified to ensure that the acid value meets the specifications of general POE refrigeration lubricating oil.

In a refrigeration system that is easily in contact with electrical materials, the dielectric strength is a basic and important parameter for evaluating refrigeration lubricants. Excessively low dielectric strength can easily lead to a short circuit during operation and cause the motor to burn out. The main factors affecting the dielectric strength are not only the characteristics of the structure of the refrigeration lubricating oil, but also the removal of impurities after the reaction (including residual unreacted raw materials, catalysts, etc.). Examples 1 to 9 of the present invention are all purified to ensure that the dielectric strength meets the specifications of general POE refrigeration lubricating oils.

Table 1: Comparison of miscibility between the high-viscosity refrigeration lubricants of Examples 1-6 and Comparative Examples 1-2 and R134a refrigerant (kinematic viscosity at 40°C≧120cSt)

Generally speaking, the higher the viscosity, the worse the miscibility with refrigerant. However, it can be found from the above table that in the present invention, the kinematic viscosity of POE in Examples 1 to 6 is from 220cSt to 400cSt, which is higher than the kinematic viscosity of 120 to 220cSt in Comparative Examples 1 to 2, but it has a higher kinematic viscosity than Comparative Examples 1 to 2. Lower two-phase separation temperature.

The miscibility between POE and refrigerant in Examples 1-6 of the present invention is better than that of commercial products in Comparative Examples 1-2, which can better meet the requirements of evaporator oil return and heat transfer, and because of higher viscosity, it can provide better performance for compressors. Excellent sealing protection, reducing the possibility of refrigerant leakage, making the compressor more efficient (especially for screw compressors).

Table 2: Comparison of miscibility between medium and low viscosity refrigeration lubricants of Examples 7-8 and Comparative Example 3 and R134a refrigerant (kinematic viscosity at 40°C<120cst)

Compared with the commercial product of Comparative Example 3, the POE of Examples 7-8 of the present invention has the same or higher viscosity, and the miscibility with R134a refrigerant is obviously better, in addition to ensuring that the evaporator does not have any risk of oil return , It can provide sealing protection of the compressor, prevent refrigerant leakage and improve operating efficiency.

Table 3: The ratio of medium and low viscosity refrigerating lubricating oil and R410A refrigerant of Examples 7 to 8 and Comparative Example 3

Comparison of miscibility (kinematic viscosity at 40°C<120cst)

R410A refrigerant is commonly used in rotary compressors commonly used in household air conditioners. Generally speaking, due to the large difference in polarity, the miscibility of the same polyol ester refrigeration lubricating oil with R410A refrigerant is often worse than that of R134a. However, the results of the miscibility analysis in the above table show that even though the kinematic viscosity of Example 7 is as high as 90cst (providing better sealing performance), its miscibility with R410A is still better than that of commercially available products, and the miscibility of Example 8 with R410A is the same Excellent, but the viscosity is lower than Example 7, the focus is to reduce the running resistance (Dragforce)

Table 4: Comparison of operating viscosities of mixtures containing high-viscosity ISO220 grade refrigeration lubricants and R134a refrigerants

In screw compressors, refrigeration lubricating oil with a viscosity grade of ISO220 and R134a refrigerant is a common combination. Under the operating conditions 1-2 of Table 4, comparing the POE of Example 4 of the present invention with the commercially available product of Comparative Example 1, it can be found that although the original kinematic viscosity of the refrigeration lubricating oil is also 220cSt, the POE of Example 4 of the present invention except In addition to the better two-phase separation temperature, the kinematic viscosity of the mixture in Example 4 is higher no matter under the operating condition 1 of high load (high load) or the operating condition 2 of low load (Lowload), ensuring lubrication Thick oil film, better lubricity and good sealing.

Table 5: Comparison of operating viscosities of mixtures containing medium and low viscosity ISO68-90 grades of refrigeration lubricants and R134a refrigerants

In addition to the better two-phase separation temperature of the POE of Examples 7-8 of the present invention, whether it is under high load (high load) operating condition 1 or under low load (Lowload) operating condition 2, Examples 7-8 The kinematic viscosity of the mixture of 8 is higher than that of the commercially available product in Comparative Example 3, ensuring a thicker lubricating oil film, better lubricity and good sealing.

Table 6: Comparison of operating viscosities of mixtures containing medium and low viscosity ISO68-90 grade refrigeration lubricants and R410A refrigerants

Rotary compressors commonly used in household air conditioners often use R410A refrigerant with refrigeration lubricating oil of ISO68 viscosity grade. In addition to the better two-phase separation temperature of the POEs of Examples 7-8 of the present invention, whether it is under high-load operating conditions 3, or under medium-low load operating conditions 4 and 5, Examples 7-8 The kinematic viscosity of the mixture is higher than that of the commercial product in Comparative Example 3, which ensures a thick lubricating oil film, better lubricity and good sealing.

Table 7: Comparison of thermal stability of sealed tubes (R134a)

＊Evaluation criteria: ◎No change ○Slight color change ΔSignificant color change

Test method: ANSI/ASHRAE standard 97-2007

Thermal Stability Comparison of Sealed Tubes (R410A)

＊Evaluation criteria: ◎No change ○Slight color change ΔSignificant color change

Test method: ANSI/ASHRAE standard 97-2007

In the refrigeration system, to evaluate the stability of refrigeration lubricating oil, the most commonly used method is the sealed tube thermal oxidation stability test method. The biggest difference between this method and the general method for evaluating the stability of lubricating oil is that the test is performed in a high-temperature and high-pressure refrigerant environment, which can speed up the identification of differences in the stability of refrigerated lubricating oil. The worse the thermal oxidation stability is, the easier it is to cause system blockage, corrosion and increased wear.

The POE of the embodiment of the present invention maintains excellent thermo-oxidative stability no matter in the environment of R134a or R410A.

Hydrolytic stability comparison (ASTMD-2619)

Although generally speaking, the chance of exposure to moisture in a refrigeration system is minimal, for large refrigeration systems, it is still possible for some moisture to enter the refrigeration system due to negligence in operation. Therefore, the provision of hydrolysis-resistant refrigeration lubricants becomes an important property evaluation tool.

As shown in the table above, according to the results of the hydrolysis test, the POE of the present invention has good stability against hydrolysis.

Claims (13)

1. A refrigeration lubricating oil composition comprising tripentaerythritol (TriPE), dipentaerythritol (DiPE), pentaerythritol (PE) or a mixture thereof and one or more linear or branched saturated or unsaturated C _{4- 20} Polyol ester products obtained by the reaction of fatty acids. 2. A refrigerated lubricating oil composition, which comprises polyhydric alcohol ester products obtained by reacting tripentaerythritol (TriPE) with one or more linear or branched saturated or unsaturated C _4-20 fatty acids, Polyol ester products obtained by reacting pentaerythritol (DiPE) with one or more linear or branched saturated or unsaturated C _4-20 fatty acids or by pentaerythritol (PE) and one or more linear or branched A mixture of polyol ester products obtained by the reaction of chain saturated or unsaturated C _4-20 fatty acids. 3. The refrigeration lubricating oil composition as claimed in claim 1 or 2, wherein the polyol ester product has the following properties: the miscible temperature with hydrofluorocarbon (HFC) refrigerant and hydrofluoroolefin (HFO) refrigerant is low The kinematic viscosity (kinematic viscosity) at -25°C (20% polyol ester product in refrigerant) and 40°C is between 46 and 460cSt. 4. The refrigeration lubricating oil composition as claimed in claim 1 or 2, wherein the fatty acid can be a C _5-10 fatty acid. 5. The refrigeration lubricating oil composition as claimed in claim 4, wherein the fatty acid comprises n-valeric acid, n-hexanoic acid, n-heptanoic acid, mixed acids of _C8-10 , 2-methylbutyric acid, 2-ethylhexyl acid, 3,5,5-trimethylhexanoic acid, or neodecanoic acid. 6. The refrigeration lubricating oil composition according to claim 1 or 2, which additionally comprises extreme pressure additives, metal deactivators, acid scavengers, antioxidants, or other synthetic refrigeration lubricating oils. 7. The refrigeration lubricating oil composition as claimed in claim 6, wherein the other synthetic refrigeration lubricating oil is polyalkylene glycol (PAG) or polyvinyl ether (PVE). 8. The refrigeration lubricating oil composition according to claim 3, wherein the refrigerant comprises hydrofluorocarbon (HFC) refrigerant or hydrofluoroolefin (HFO) refrigerant. 9. The refrigeration lubricating oil composition according to claim 8, wherein the hydrofluorocarbon (HFC) refrigerant is R134a, R410A, R404A or R407C, and the hydrofluoroolefin (HFO) refrigerant is R1234ze or R1234yf. 10. The refrigeration lubricating oil composition according to claim 8, wherein the refrigerant is R134a or R410A. 11. The refrigeration lubricating oil composition according to claim 6, wherein the ratio of the refrigeration lubricating oil composition to the refrigerant can be 99/1˜1/99. 12. The refrigeration lubricating oil composition as claimed in claim 6, wherein the added amount of the extreme pressure additive is 0-4% by weight, the metal deactivator is 0-0.5% by weight, the acid scavenger is 0-2% by weight, and the Antioxidant 0-1% by weight. 13. The refrigeration lubricating oil composition according to claim 6, wherein the ratio of the polyol ester product to the PAG or PVE is 20-100%.