阅读说明：本技术 一种冷冻机油组合物及其制备方法 (Refrigerating machine oil composition and preparation method thereof ) 是由 胡余生 林新俊 郭小青 史正良 徐嘉 于 2020-09-22 设计创作，主要内容包括：本发明属于润滑油技术领域,提供一种冷冻机油组合物及其制备方法,其组分包括：基础油：90-99.8%重量份,其中含有多元醇苯甲酸混合酯油；抗氧剂：0.05-3%重量份；酸捕捉剂:0.05-3%重量份；抗磨剂:0.05-2%重量份；抗泡剂:0.05-2%重量份。所述基础油包含有苯甲酸的酯化物,苯甲酸在所述有机酸总量中所占的比例为4-35mol%,余量为C4-18直链或支链脂肪酸。本发明组合物以多元醇酯基础油和必要的添加剂组成,其中基础油主要为含有多元醇苯甲酸混酯成分的新结构。这种通过多元酯分子中引入苯环,形成苯甲酸的酯结构,从本质上提高了基础油的稳定性,且兼顾了与R32制冷剂的相溶性,同时具有良好的润滑性与抗氧化性能。(The invention belongs to the technical field of lubricating oil, and provides a refrigerating machine oil composition and a preparation method thereof, wherein the refrigerating machine oil composition comprises the following components: base oil: 90-99.8% by weight of a polyol benzoate mixed ester oil; antioxidant: 0.05-3% by weight; 0.05 to 3 weight percent of acid catcher; 0.05 to 2 weight percent of antiwear agent; 0.05 to 2 weight percent of antifoaming agent. The base oil contains esterified benzoic acid, the benzoic acid accounts for 4-35mol% of the total amount of the organic acid, and the balance is C4-18 straight chain or branched chain fatty acid. The composition of the invention consists of polyol ester base oil and necessary additives, wherein the base oil mainly has a new structure containing polyol benzoate mixed ester components. The benzene ring is introduced into the polyester molecules to form an ester structure of benzoic acid, so that the stability of the base oil is substantially improved, the compatibility with the R32 refrigerant is considered, and the lubricating property and the oxidation resistance are good.)

1. A refrigerator oil composition characterized by comprising:

base oil: 90-99.8% by weight of a polyol benzoate mixed ester oil;

antioxidant: 0.05-3% by weight;

0.05 to 3 weight percent of acid catcher;

0.05 to 2 weight percent of antiwear agent;

0.05 to 2 weight percent of antifoaming agent.

2. The refrigerator oil composition of claim 1, wherein the base oil comprises an esterified product of benzoic acid, wherein benzoic acid accounts for 4 to 35mol% of the total amount of the organic acids, and the balance is C4 to 18 straight or branched chain fatty acids.

3. The refrigerator oil composition of claim 2, wherein the benzoic acid comprises at least one of benzoic acid and benzoic acid with alkyl or alkoxy substituents.

4. The refrigerator oil composition of claim 3 wherein the benzoic acid is a C4-18 straight or branched chain fatty acid in an amount of 10 mol% to 30 mol% based on the total amount of organic acid raw materials.

5. The refrigerator oil composition of claim 1, wherein the mixed ester comprises any one of: neopentyl glycol, trimethylolethane, trimethylolpropane, pentaerythritol, dipentaerythritol.

6. The refrigerator oil composition of claim 5 wherein the mixed ester comprises one or more ester oils of formula I or formula II wherein R is₁、R₂、R₃、R₄And R₅Each independently is C₃-C₁₇And not simultaneously phenyl;

formula I;

and (5) formula II.

7. The refrigerator oil composition of claim 1, wherein the antioxidant comprises any one of: hindered phenols, diarylamines, phenothiazines, organic sulfonates, metal dialkyldithiocarbamates.

8. The refrigerator oil composition of claim 1, wherein the acid scavenger comprises any one of: glycidyl ester type epoxy compounds, glycidyl ether type epoxy compounds, and phenyl glycidyl ether.

9. The refrigerator oil composition of claim 1 wherein the antiwear agent comprises any one of: alkyl phosphates and alkyl phosphates, dialkyl dithiophosphates and phosphate esters; the anti-foaming agent comprises polydimethylsiloxane containing silicon or polyacrylate containing non-silicon.

10. A method for preparing a refrigerator oil composition according to any one of claims 1 to 9, comprising the steps of: the polyol mixed ester is prepared by adding fatty acid and benzoic acid in batches in sequence according to the molar ratio of hydroxyl to carboxyl of 1:1.1, and carrying out catalytic esterification reaction, wherein the target product of base oil is obtained by carrying out acid removal, water removal, decoloration adsorption and refining post-treatment;

and adding the prepared base oil into a blending container, adding an antioxidant, an acid trapping agent, an antiwear agent or an antifoaming agent, and fully and uniformly mixing to obtain the target refrigerating machine oil composition product.

Technical Field

The invention belongs to the technical field of lubricating oil, and provides a refrigerating machine oil composition and a preparation method thereof.

Background

In recent years, as the depletion of the ozone layer has been highlighted, refrigerants of the CFCs (chlorofluorocarbons) and HCFCs (hydrochlorofluorocarbons) containing chlorine are being banned and phased out according to the requirements of the Montreal protocol. HFCs (hydrofluorocarbon) refrigerants have been developed as alternative refrigerants because of their low global warming index (GWP) and non-ozone-depleting effect. In a refrigeration system, the refrigerating machine oil composition selected when CFCs and HCFCs are used as refrigerants is usually mineral oil, alkylbenzene oil and the like; after changing the refrigerant type, problems have been associated with the compatibility of the refrigerator oil composition with the refrigerant, the solution viscosity, the lubricity, the thermo-oxidative chemical stability, and the like.

Currently, synthetic polyol ester (POE) base oils or Polyether (PVE) base oils are frequently used in Hydrofluorocarbon (HFC) refrigeration systems. Among them, trimethylolpropane ester and pentaerythritol ester oils of C4-C9 fatty acids are commonly used as polyol ester oils. With the miniaturization of equipment of the refrigeration compressor for the purposes of energy conservation, environmental protection and the like, the heat load of the compressor is increased; under severe conditions, the synthetic ester refrigerator oil composition is more likely to deteriorate and reduce the lubricating performance. To ensure long-term high-speed, reliable operation of refrigeration compressors, further improvements in thermo-oxidative stability and anti-wear properties of the refrigerator oil composition are desired.

In order to improve and compromise the lubricity, compatibility and stability of synthetic esters and to limit the effect of improving the quality characteristics of the refrigerating machine oil composition by changing the formulation of additives in the refrigerating machine oil composition, some patents propose to improve the stability and anti-wear properties of the refrigerating machine oil composition starting from the structure of the base oil, such as:

patent document CN104093694B discloses a mixed polyol ester composed of pentaerythritol fatty acid ester or dipentaerythritol fatty acid ester, which is compatible with R32 refrigerant and has good abrasion resistance.

Patent document CN 105505540a discloses a lubricating base material suitable for hydrofluorocarbons R32, R23, R134a, R125a or a mixture thereof as a refrigerant, and the hydrolytic stability of a refrigerator oil composition is improved by using an alkylated aromatic hydrocarbon in combination with a polyol ester.

Patent document CN 104254515B discloses a method for producing a mixed ester of pentaerythritol or mixed polyol and carboxylic acid, which shows good balance among compatibility, lubricity, oxidation-hydrolysis stability, and the like. However, the refrigerating machine oil composition has not been disclosed or disclosed to have good compatibility with a single R32 refrigerant and to have both stability and lubricity.

The above patent schemes can provide better lubricating performance to a certain extent, but the aspects of lubricating performance, compatibility and stability of the synthetic ester still have shortcomings. In addition, most of these polyol esters are esters of fatty acids with neopentyl polyol, and the basic structural units are esters of fatty acids.

Disclosure of Invention

In order to solve the problems, the invention provides a refrigerator oil composition with a novel structure and a preparation method thereof, wherein the refrigerator oil composition consists of polyol ester base oil and necessary additives. Wherein, the base oil mainly has a new structure containing polyol mixed benzoate component. The benzene ring is introduced into the polyester molecules to form an ester structure of benzoic acid, so that the stability of the base oil is substantially improved, the compatibility with the R32 refrigerant is considered, and the lubricating property and the oxidation resistance are good.

The technical scheme of the invention is as follows:

a refrigerator oil composition characterized by comprising:

base oil: 90-99.8% by weight of a polyol benzoate mixed ester oil;

antioxidant: 0.05-3% by weight;

0.05 to 3 weight percent of acid catcher;

0.05 to 2 weight percent of antiwear agent;

0.05 to 2 weight percent of antifoaming agent.

Further, the base oil contains esterified substances of benzoic acid, the proportion of the benzoic acid in the total amount of the organic acid is 4 mol% -35mol%, and the balance is C4-18 straight chain or branched chain fatty acid.

Further, the benzoic acid comprises at least one of benzoic acid and benzoic acid with alkyl or alkoxy substituent.

Further, the benzoic acid accounts for 10 mol% to 30 mol%, more preferably 15 mol% to 20 mol% of the total amount of the organic acid raw material.

Further, the mixed ester includes any one of: neopentyl glycol, trimethylolethane, trimethylolpropane, pentaerythritol, dipentaerythritol. From the viewpoint of structural stability, mixed esters of hindered alcohols having good symmetry, such as neopentyl glycol, trimethylolethane, trimethylolpropane, pentaerythritol, dipentaerythritol, and the like, are preferable; esters of pentaerythritol or dipentaerythritol are more preferable from the viewpoint of better thermal stability and oxidation stability.

Further, the mixed ester comprises one or more ester oils in formula I or formula II, wherein R in formula I or formula II₁、R₂、R₃、R₄And R₅Each independently is C₃-C₁₇Alkyl or phenyl (-C)₆H₅) And are not simultaneously phenyl;

formula I;

and (5) formula II. The mixed ester of the present invention may contain a polyol in which a part of the hydroxyl groups is not esterified as impuritiesAnd (3) an ester.

Further, the antioxidant comprises any one of the following: hindered phenols, diarylamines, phenothiazines, organic sulfonates, metal dialkyldithiocarbamates.

Further, the acid trapping agent includes any one of: glycidyl ester type epoxy compounds, glycidyl ether type epoxy compounds, and phenyl glycidyl ether.

Further, the antiwear agent includes any one of: alkyl phosphates and alkyl phosphates, dialkyl dithiophosphates and phosphate esters.

Further, the anti-foaming agent comprises polydimethylsiloxane containing silicon or polyacrylate containing non-silicon.

In particular, in the refrigerator oil composition of the present invention, the types of the refrigerator oil additives of the present invention (antioxidant, acid scavenger, anti-wear agent, anti-foaming agent) are not particularly limited, and other conventional techniques can be used.

Further, the kinematic viscosity of the base oil at 40 ℃ is 17-600mm²S, preferably 45 to 120mm²S, more preferably 60 to 95mm²/s。

The inventor of the application obtains good thermo-oxidative chemical stability in a hydrofluorocarbon refrigerant (R32) system due to the polyol-containing benzoate component, and simultaneously has higher viscosity index, lower pour point and excellent abrasion resistance through a plurality of creative tests.

According to the invention, neopentyl benzoate is introduced into the polyol ester base oil, and the structural stability of the polyol ester base oil can be improved by utilizing the regional shielding effect of a pi-pi conjugated system formed by a benzene ring and an ester group;

because ester bonds in ester molecules have stronger polarity, the ester bonds can be adsorbed on the friction surface to generate an oil film with higher strength, and the friction coefficient of the friction surface is reduced. Therefore, the more polar the synthetic ester base oil, the better the lubricating and friction reducing effects. The formula is calculated according to the polarity or non-polarity of the ester:

index of non-polarity: (NPI) Relative Molecular Mass (RMM) of total carbon atomsNumber of carbonyl groups 100

For esters having the same total number of carbon atoms and carbonyl groups, the lower the relative molecular mass, the smaller the NPI and the more polar. I.e., polyol esters having the same total number of carbon atoms and carbonyl groups, the higher the degree of unsaturation, the greater the polarity. Therefore, the benzoic acid with the unsaturation degree is introduced into the synthetic ester, which is beneficial to improving the polarity of the base oil, thereby playing a role in improving the lubricating property of the base oil.

The invention also provides a preparation method of the refrigerator oil composition, which comprises the following steps: the polyol mixed ester is prepared by adding fatty acid and benzoic acid in batches in sequence according to the molar ratio of hydroxyl to carboxyl of 1:1.1, and carrying out catalytic esterification reaction, wherein the target product of base oil is obtained by carrying out acid removal, water removal, decoloration adsorption and refining post-treatment;

and adding the prepared base oil into a blending container, adding an antioxidant, an acid trapping agent, an antiwear agent or an antifoaming agent, and fully and uniformly mixing to obtain the target refrigerating machine oil composition product.

The present invention relates to a polyol/benzoic acid mixed ester refrigeration oil which contains an esterified product of any polyol ester with a benzoate component and which can be used together with a hydrofluorocarbon R-32 refrigerant.

The invention solves the following technical problems:

1. aiming at the problem that the lubricating property of the synthetic ester refrigerator oil composition is reduced because the composition is easy to deteriorate under severe conditions, in order to ensure that the refrigeration compressor can operate at high speed and reliability for a long time, the lubricating property, the thermal oxidation stability and the like of the refrigerator oil composition need to be further improved;

2. the problem that the ester refrigerator oil composition cannot simultaneously achieve stability, compatibility and lubricating performance in a refrigerator using an R32 refrigerant is solved.

The invention has the beneficial effects that:

1. the refrigerating oil composition has good compatibility with hydrofluorocarbon R32 refrigerant as refrigerant;

2. the refrigerating oil composition has good thermal oxidation stability and excellent wear resistance;

3. the base oil in the refrigerator oil provided by the invention has a benzoate structure and relatively high molecular weight, so that the base oil has good stability, compatibility and lubricity;

4. in a hydrofluorocarbon R32 refrigerant system, a compressor using the refrigerator oil of the present invention as a working fluid can achieve reliable operation under a relatively severe environment.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the detailed description and specific examples, while indicating the scope of the invention, are intended for purposes of illustration only and are not intended to limit the scope of the invention.

Examples

The present invention provides various specific examples of refrigerator oil compositions, as shown in examples 1-8, comparative examples 1-8. In examples 1 to 8 and comparative examples 1 to 8, pentaerythritol or dipentaerythritol was selected as the alcohol component; c5, C8 and C9 fatty acids with benzoic acid as the organic carboxylic acid component; the concrete implementation formula of the preparation of the polyol benzoate mixed ester frozen base oil according to the raw material proportion of the hydroxyl carboxyl molar ratio of 1:1.1 is described in detail. The basic properties of the obtained refrigerator oil are shown in tables 1 and 2.

The performance test basis in the invention is as follows: pour point determined according to GB/T3535-; the flash point determined according to GB/T3536-; water content determined according to GB/T11133-2015; acid value according to GB/T7304-; hydroxyl number determined according to HG/T2709-.

The antiwear properties were determined according to petrochemical industry standard SH/T0189-92; the thermal decomposition temperature was determined according to a self-established experimental method; the oxidation induction period is determined according to the petrochemical industry standard SH/T0719-; the intermiscibility is determined according to the standard SH/T0699-; the acid value of the refrigerating machine oil is preferably 0.1 mg.KOH/g or less, more preferably 0.05 mg.KOH/g or less, in order to prevent corrosion of metals used for parts in the refrigeration system and influence on the stability of the refrigerating machine oil itself.

According to the chemical industry standard SH/T0719-. And (3) placing the pressure sealed sample vessel on a PDSC instrument test sample platform, heating the sample at the speed of 100 ℃/min from room temperature, and measuring the oxidation induction period under the conditions of oxygen atmosphere, 3.5MPa +/-0.2 MPa and the flow rate of 100 mL/min. The test results are shown in table 3.

According to the self-constructed experimental method "freezer oil thermogravimetry", a 15mg oil sample is placed on a suitable thermogravimetric analyzer (TGA) sample tray, which is placed on a sample holder and heated to 40-600 ℃ in a 50mL/min nitrogen stream at a rate of 20 ℃/min. During the entire process, the thermogravimetric analyzer monitors and records the mass of the sample lost due to thermal decomposition. The thermogravimetric loss was measured under the same thermogravimetric conditions on a curve of the mass loss fraction of the sample versus temperature (thermogravimetric curve) measured subsequently. The test results are shown in table 3.

According to the testing method of the compatibility of the refrigerating machine oil and the refrigerant of SH/T0699-2000 'refrigerating machine oil' in the petrochemical industry, a proper amount of oil sample and the refrigerant R32 are put into a test tube, the oil sample and the refrigerant are fully mixed at room temperature or elevated temperature, then the mixture is cooled in a cold bath, and the temperature of the solution when the solution is separated into two phases or the whole solution is emulsified is measured to evaluate the compatibility of the refrigerating machine oil and the refrigerant. The test results are shown in table 4.

According to the petrochemical industry standard SH/T0189-92 'method for measuring the abrasion resistance of lubricating oil', abrasion resistance parameters of an oil sample are measured, and the abrasion resistance of the oil product is evaluated by obtaining the average wear scar diameter and the friction coefficient. The test was carried out under the conditions of load 392N, temperature 75 ℃ and rotation speed 1200r/min of a MMW-1 vertical universal friction tester, and the test results are shown in Table 5.

TABLE 1 examples

TABLE 2 comparative examples

Note: no testing was performed because the synthetic base oil was a solid at ambient temperature.

TABLE 3 analysis of thermal and oxidative stability

Note: the evaporation loss rate of the base oil samples 1-11 and 15-16 is more than 99 percent.

TABLE 4 refrigerant compatibility test with R32

Note: "compatible" means that the refrigerant and the refrigerator oil are dissolved in each other, and "separated" means that the refrigerant and the refrigerator oil are separated into two layers.

TABLE 5 four-ball Friction test results

Examples 1-4 in Table 1 show that increasing the proportion of benzoic acid in the base oil formulation results in an increase in the viscosity of the base oil but has an effect on the viscosity index or pour point of the base oil. Secondly, comparative examples 1 to 6 show that the amount of benzoic acid is too low or too high and that the kinematic viscosity at 40 ℃ does not meet the viscosity requirement of conventional refrigerator oils or becomes solid. Therefore, in order to ensure good low-temperature fluidity and viscosity of the base oil, the proportion of benzoic acid needs to be balanced and controlled, and the amount of benzoic acid added is preferably 5mol% to 35mol% and more preferably 15 mol% to 20 mol% of benzoic acid based on the total amount of the organic acid components.

Analysis of the data in Table 2 (e.g., example 1 versus comparative example 1) shows that the addition of the benzoic acid feed stock component results in a significant increase in the viscosity of the base oil, and a concomitant increase in the viscosity index. This experiment shows that multi-component and complex structured polyol esters have higher viscosity indices than single component. Further, the viscosity of the polyol benzoic acid mixed ester of benzoic acid and other fatty acid (fatty acid having carbon number greater than 5 or more) is more significantly affected by the amount of benzoic acid added, and when the ratio of benzoic acid exceeds 40mol% of the total amount, the base oil product is easily made solid at room temperature.

The test results in Table 3 show that base oils containing a benzoic acid component (e.g., base oils 1-4) have significantly longer oxidative induction periods than base oils without a benzoic acid component (base oil 9). Further analysis found that as the proportion of benzoic acid added increased, the corresponding induction period for base oil oxidation also increased. Therefore, we speculate that the introduction of the benzoic acid component in the frozen base oil is a direct reason for the improvement of the antioxidant performance of the base oil in the patent. Of course, a small amount of antioxidant may be added to obtain a refrigerator oil composition with high antioxidant properties.

The several base oils of examples 1-4 exhibited significant differences in anti-wear effects and exhibited increased benzoic acid content and decreased scrub spot diameter and scrub spot coefficient. Further, as a result of the test conducted by analyzing base oils 3 and 9, it was found that the pentaerythritol benzoic acid mixed ester (base oil 3) synthesized by adding the benzoic acid starting component had a significantly lower coefficient of friction than the pentaerythritol isovalerate (base oil 9) without adding the benzoic acid component. Also, a similar rule can be obtained by comparing the test results of example 8 with those of comparative example 8. The experimental result shows that the introduction of the benzoic acid component is a direct beneficial influence factor for improving the anti-wear and anti-friction performance of the oil sample. Of course, other necessary antiwear additives may be added in order to obtain a high quality antiwear lubricating effect.

In conclusion, the kinematic viscosity, heat, oxidation induction period, the wear-scar diameter and the like of the polyol benzoic acid mixed ester provided by the embodiment of the patent all have beneficial effects along with the increase of the addition amount of benzoic acid; the indexes of the two-layer separation temperature and the pour point of the base oil and the R32 refrigerant have adverse effects along with the increase of the addition amount of the benzoic acid. Therefore, it is important to control the raw material ratio of benzoic acid and fatty acid in order to improve the overall performance of the refrigerator oil.

Tests prove that the polyol benzoic acid mixed ester oil disclosed by the patent can be used for obtaining base oil with different kinematic viscosities by adjusting the proportion of benzoic acid and fatty acid, and the kinematic viscosity range can be 17-600mm at 40 DEG C²A base oil with a viscosity index of 80 to 120; the low-temperature two-layer separation of the refrigerator oil composition consisting of the R32 refrigerant can be lower than 0 ℃, and the mixture viscosity of the refrigerator oil composition is more than 3.5mm under the conditions of 80 ℃ and 3.4MPa (R32 refrigerant)²And s. In addition, the compatibility, thermal and oxidative stability and excellent wear resistance of the refrigerating machine oil and the R32 refrigerant can be considered at the same time by adjusting the proportion of the base oil, namely the benzoic acid, to the fatty acid.

Industrial applicability

As can be seen from the test data in tables 1-5, the present invention is useful as a refrigerator oil working fluid composition in refrigerators with hydrofluorocarbon R32 refrigerant.

The pentaerythritol benzoate mixed base oil and the composition thereof provided by the embodiment of the invention have good compatibility with a hydrofluorocarbon R32 refrigerant, and the frozen base oil containing the new structure of pentaerythritol benzoate has good performances of wear resistance, wear reduction and thermal oxidation stability.

It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Furthermore, it should be understood that although the present description refers to embodiments, not every embodiment may contain only a single embodiment, and such description is for clarity only, and those skilled in the art should integrate the description, and the embodiments may be combined as appropriate to form other embodiments understood by those skilled in the art. It should be noted that the technical features not described in detail in the present invention can be implemented by any prior art in the field.