Long-life screw air compressor oil composition and preparation and evaluation method thereof

Abstract

The invention discloses a long-life screw air compressor oil composition and a preparation and evaluation method thereof. The composition is prepared from the following components in percentage by mass: 1.2 percent to 4 percent of an antioxidant, 0.02 percent to 0.1 percent of a metal deactivator, 0.02 percent to 0.5 percent of an ash-free extreme pressure anti-wear agent, 0.01 percent to 0.1 percent of an anti-rust agent, 0.01 percent to 0.03 percent of an anti-foaming agent and the balance of synthetic base oil. The method evaluates the composition in combination with the use of a rotational oxygen bomb method and a linear voltammetry. The long-life screw air compressor oil composition provided by the invention has excellent oxidation resistance, can provide good anti-corrosion protection for metal equipment, and reduces the generation of oil sludge paint films. The composition provided by the invention is stable and excellent in performance, the oil change period of an oil product can reach 16000 hours under a severe working condition, and the lubricating requirement of the current screw air compressor is met. The compressor oil evaluation method adopted by the invention not only can be used for long-life screw air compressor oil, but also is suitable for other types of screw air compressor oil, and has certain universality.

Description

Technical Field

[0001] The invention relates to a long-life screw air compressor oil composition and a preparation and evaluation method thereof. Background Art

[0002] As a general-purpose mechanical equipment, air compressors are widely used in machinery manufacturing, mining and metallurgy, clothing and textiles, electronics and electricity, medicine and food and other industries. At present, the most commonly used compressor types are: screw type and piston type. Compared with piston air compressors, screw air compressors have the characteristics of simple structure, small size, light weight, large single-machine pressure ratio, more energy-saving and environmental protection, which also makes screw air compressors gradually become the mainstream of the compressor market. The compression of screw compressor gas depends on the change of volume, and the change of volume is achieved by the rotation of a pair of rotors of the compressor in the casing. The motor drives the gear shaft through an elastic coupling, and then transmits it to the male rotor through gear transmission. The injected oil is effectively compressed between the rotor teeth after mixing with the air. The oil forms an oil film between the rotor teeth to avoid direct contact between metal and metal, seal the gaps between the rotor parts and absorb most of the compression heat, while reducing the power consumption of the friction surface, sealing the working volume of gas compression and ensuring the safety of the compressor. Therefore, in the use of screw air compressors, the selection of screw air compressor oil is also particularly important.

[0003] The types of screw air compressor oil products currently in use are: mineral type, semi-synthetic type, and synthetic type. The main difference is that the oil change cycle is different, roughly divided into 2000, 2000-4000, and more than 4000 hours. Among them, synthetic screw air compressor oil products have been widely used in the market due to their excellent comprehensive performance and long oil change period. The generally recommended oil change period is 8000 hours. At present, the evaluation method for the service life of compressor oil products is mainly carried out through the two methods of rotating oxygen bomb and TOST. Summary of the invention

[0004] In order to increase the selection space of synthetic screw air compressor oil products and meet the user's requirements for high quality, long oil change period and low maintenance cost of oil products, a method of evaluating the compressor oil product is adaptively provided. The embodiment of the present invention provides a long-life screw air compressor oil composition and an evaluation method thereof to obtain a compressor oil product with a longer oil change period, and predict the actual service life of the oil product through a scientific evaluation method.

[0005] As one aspect of the present invention, it relates to a long-life screw air compressor oil composition, which includes the following components by mass percentage: 1.2% to 4% antioxidant, 0.02% to 0.1% metal passivator, 0.02% to 0.5% ashless extreme pressure anti-wear agent, 0.01% to 0.1% rust inhibitor, 0.01% to 0.03% anti-foaming agent, and the remainder is synthetic base oil.

[0006] In one or some possible embodiments, the antioxidant comprises an alkylated diphenylamine antioxidant; the alkylated diphenylamine antioxidant is selected from one of butyloctyldiphenylamine and dinonyldiphenylamine.

[0007] In one or some possible embodiments, the antioxidant further includes: a naphthylamine antioxidant; the naphthylamine antioxidant is selected from N-phenyl-α-naphthylamine or alkyl-phenyl-α-naphthylamine.

[0008] In one or some possible embodiments, the metal deactivator is selected from one or more of benzotriazole derivatives, methylbenzotriazole derivatives or N,N-dialkylaminomethylenebenzotriazole derivatives.

[0009] In one or some possible embodiments, the ashless extreme pressure and anti-wear agent is selected from one of alkyl phosphates, phosphites or thiosulfates.

[0010] In one or some possible embodiments, the rust inhibitor is selected from one or more of alkenyl succinic acid, alkenyl succinic acid half ester or barium dinonylnaphthalene sulfonate.

[0011] In one or some possible embodiments, the anti-foaming agent is selected from silicone anti-foaming agents or polyacrylate anti-foaming agents.

[0012] In one or some possible embodiments, the synthetic base oil is selected from one or more of olefins, alkyl naphthalenes or polyol esters.

[0013] As another aspect of the present invention, it relates to a method for preparing the long-life screw air compressor oil composition, the method comprising the following steps:

[0014] S1. Add synthetic base oil according to mass percentage and raise the temperature to 45±5°C under stirring;

[0015] S2. Under stirring conditions, antioxidant, metal passivator, ashless extreme pressure anti-wear agent, rust inhibitor and anti-foaming agent are added in sequence to the heated synthetic base oil in S1, and the mixture is heated and mixed to obtain a long-life screw air compressor oil composition.

[0016] As another aspect of the present invention, it relates to a method for evaluating the long-life screw air compressor oil composition. The method combines the use of a rotating oxygen bomb method and a linear voltammetry method to evaluate the composition.

[0017] In one or some possible embodiments, the method includes:

[0018] The composition is subjected to a cyclic test within a set time period using a rotating oxygen bomb method;

[0019] The cyclic test includes: taking 9% of the composition sample each time, using linear voltammetry to evaluate the remaining service life of the composition sample to test the remaining content of the antioxidant in the composition sample, and adding an equal amount of the composition sample at the same time to start the next cycle until the linear voltammetry result shows that the remaining content of the antioxidant is zero, and the test ends.

[0020] In one or some possible embodiments, the long-life screw air compressor oil composition has a cycle number of not less than 16 times and a service life of not less than 16,000 hours.

[0021] In the long-life screw air compressor oil composition provided by the present invention, the antioxidant content has a certain retention, so that the oil has excellent antioxidant properties, and can provide good anti-corrosion protection for metal equipment and reduce the generation of sludge and paint film. The composition provided by the present invention has stable and excellent performance. Under severe working conditions (exhaust temperature is greater than 100°C), the oil change cycle of the oil can reach 16,000 hours, meeting the lubrication requirements of current screw air compressor equipment.

[0022] The evaluation method of compressor oil products adopted in the present invention can be used not only for the long-life screw air compressor oil products of the present invention, but also for other types of screw air compressor oil products, and has a certain universality. This evaluation method improves the test conditions of the rotating oxygen bomb, cyclically tests the oxidation stability of the oil products, and uses the linear voltammetry (RULER) test to detect the content of antioxidants in the oil products, and evaluates the remaining service life of the oil products after oxidation. When the remaining content of the antioxidant is zero, the experiment ends, and the number of cycles represents the service life of the oil products. Compared with the traditional rotating oxygen bomb / TOST method, this evaluation method is closer to the actual working conditions, and the scope of application is no longer limited to mineral oils, but also applicable to various types of synthetic oils such as olefins (PAO) and polyethers. The simulated test of the remaining content of the antioxidant is basically consistent with the sampling and analysis results of the actual use test. This method can scientifically predict the oil change cycle of the oil products.

[0023] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention are realized and obtained by the structures particularly pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a curve chart of the cycle test of Example 4 of the present invention and Comparative Example 2. DETAILED DESCRIPTION

[0025] The inventors conducted experimental research with reference to a long-life screw air compressor oil and a preparation method thereof disclosed in patent CN108865358 A, which includes: the base oil is polyether and alkyl naphthalene, the additives include ashless anti-wear and anti-rust composite agent, amine-type high-temperature antioxidant, phenol-type antioxidant, composite anti-foaming agent, and metal deactivator, which can achieve a long oil change period of 12,000 hours.

[0026] The inventors refer to the patent CN107573995A disclosed a highly antioxidant long-life fully synthetic screw air compressor oil and its preparation method, and conduct experimental research, including: additives including phenolic antioxidants, amine antioxidants and aminomethyl ester antioxidants composite high-temperature antioxidants and extreme pressure anti-wear agents, corrosion inhibitors and rust inhibitors, etc. The base oil is a screw compressor oil of polyalphaolefin, saturated polyol ester or polyether, and saturated polyol ester and oil-soluble polyether are added as solubilizers to dissolve and disperse sludge and control the sludge trend. The compounding of different types of antioxidants can improve the antioxidant properties of oil products and can make the rotary oxygen bomb time reach 2700min.

[0027] Through experimental research on the above two patent documents, the inventors found that: both patents did not consider the retention of antioxidant content in long-life screw air compressor oil, and could not truly evaluate the oil change cycle of the oil in actual use.

[0028] In addition, the inventors also found that in the prior art, the service life of oil products is basically evaluated by two methods: rotating oxygen bomb and TOST. The rotating oxygen bomb method is currently a relatively fast and effective method for evaluating the oxidation stability of air compressor oil, especially synthetic compressor oil products. However, this method has certain limitations and cannot fully reflect the actual antioxidant performance and service life of oil products; the TOST test method stipulates the time required for the acid value to reach 2.0 mgKOH / g under high temperature conditions (95°C) in the presence of oxygen, water, and metal copper and iron to indicate its "oxidation life". This method is widely used to evaluate the oxidation characteristics of turbine oil or other oil products with inhibitors, and clearly stipulates that the scope of application is mineral oil with inhibitors added, and it may not be applicable to synthetic oils.

[0029] In summary, since the existing technology and evaluation methods are not as good as the inventors' expectations, the inventors made the present invention through further research and development.

[0030] The composition of the present invention can extend the service life of oil products by compounding with two amine-type antioxidants. In designing the two amine-type antioxidants, the present invention fully considers that the alkylated diphenylamine-type antioxidant has good high-temperature antioxidant ability and good synergistic effect. When used together with other additives, it can significantly extend the service life and effectively inhibit the increase in oil viscosity and the formation of oxidative deposits. In addition, the naphthylamine-type antioxidant also has outstanding high-temperature antioxidant properties, which has good effects on extending the induction period, inhibiting the late antioxidant effect and antioxidant durability of oil products, and is more suitable for compressor working conditions. Different types of amine-type antioxidants are compounded to show excellent antioxidant properties, which plays a decisive role in improving the high-temperature oxidation resistance of the oil products in the composition and extending the service life of the oil products.

[0031] The present invention is further described below in conjunction with specific examples, and the protection scope of the present invention is not limited by the following examples. The sources of materials mainly involved in the examples are all conventional commercial products.

[0032] In the following embodiments, the long-life screw air compressor oil composition is prepared by the following steps:

[0033] S1. Add synthetic base oil according to mass percentage and raise the temperature to 45±5°C under stirring;

[0034] S2. Under stirring conditions, antioxidant, metal passivator, ashless extreme pressure anti-wear agent, rust inhibitor and anti-foaming agent are added in sequence to the heated synthetic base oil in S1, and the mixture is heated and mixed to obtain a long-life screw air compressor oil composition.

[0035] Embodiment 1

[0036] The long-life screw air compressor oil composition of the present embodiment comprises the following components by mass fraction: 1.8% antioxidant (1.5% alkyl diphenylamine + 0.3% alkyl-phenyl-α naphthylamine); 0.02% metal passivator (tolyltriazole derivative); 0.05% ashless extreme pressure anti-wear agent (thiosulfate), 0.03% rust inhibitor (alkenyl succinic acid), 0.03% anti-foaming agent (1# composite anti-foaming agent), and 98.07% synthetic base oil (PAO 83.36% + alkyl naphthalene 14.71%).

[0037] The above components are mixed according to the above materials and their mass percentages to prepare a long-life screw air compressor oil composition.

[0038] Embodiment 2

[0039] The long-life screw air compressor oil composition of the present embodiment includes the following components by mass fraction: 1.2% antioxidant (0.8% alkyl diphenylamine + 0.4% N-phenyl-α naphthylamine); 0.04% metal passivator (0.01% benzotriazole derivative + 0.03% tolyltriazole derivative); 0.02% ashless extreme pressure anti-wear agent (0.01% alkyl phosphate + 0.01% phosphite), 0.02% rust inhibitor (0.01% alkenyl succinic acid + 0.01% alkenyl succinic acid half ester), 0.02% anti-foaming agent (2# composite anti-foaming agent), 98.70% synthetic base oil (86.70% PAO + 12.00% polyol ester).

[0040] The above components are mixed according to the above materials and their mass percentages to prepare a long-life screw air compressor oil composition.

[0041] Embodiment 3

[0042] The long-life screw air compressor oil composition of the present embodiment includes the following components by mass fraction: 2.2% antioxidant (2.0% alkyl diphenylamine + 0.2% N-phenyl-α naphthylamine); 0.08% metal passivator (tolyltriazole derivative); 0.02% ashless extreme pressure anti-wear agent (thiosulfate), 0.10% rust inhibitor (alkenyl succinic acid half ester), 0.02% anti-foaming agent (2# composite anti-foaming agent), 97.55% synthetic base oil (PAO 92.70% + polyol ester 4.85%).

[0043] The above components are mixed according to the above materials and their mass percentages to prepare a long-life screw air compressor oil composition.

[0044] The long-life screw air compressor oil composition prepared in this embodiment has a cycle number of not less than 16 times under the test condition of 150° C. and a service life of 16,000 hours.

[0045] Embodiment 4

[0046] The long-life screw air compressor oil composition of the present embodiment includes the following components by mass fraction: 1.9% antioxidant (1.2% alkyl diphenylamine + 0.7% N-phenyl-α naphthylamine); 0.02% metal passivator (toluene triazole derivative); 0.05% ashless extreme pressure anti-wear agent (thiosulfate), 0.10% rust inhibitor (alkenyl succinic acid half ester), 0.03% anti-foaming agent (2# composite anti-foaming agent), 97.9% synthetic base oil (PAO 90.00% + polyol ester 7.90%).

[0047] The above components are mixed according to the above materials and their mass percentages to prepare a long-life screw air compressor oil composition.

[0048] The compressor oil composition prepared in this example is evaluated by the evaluation method of the present invention. The measured data results are as follows: Figure 1 shown.

[0049] Embodiment 5

[0050] The long-life screw air compressor oil composition of the present embodiment includes the following components by mass fraction: 4.0% antioxidant (3.2% alkyl diphenylamine + 0.8% N-phenyl-α naphthylamine); 0.10% metal passivator (toluene triazole derivative); 0.26% ashless extreme pressure anti-wear agent (trialkyl phosphate), 0.06% rust inhibitor (alkenyl succinic acid), 0.01% anti-foaming agent (polyacrylate type Hi TEC 2030 anti-foaming agent), 95.57% synthetic base oil (PAO 90.25% + alkyl naphthalene 5.32%).

[0051] The above components are mixed according to the above materials and their mass percentages to prepare a long-life screw air compressor oil composition.

[0052] Embodiment 6

[0053] The long-life screw air compressor oil composition of the present embodiment comprises the following components by mass fraction: 2.6% antioxidant (1.9% alkyl diphenylamine + 0.7% N-phenyl-α naphthylamine); 0.06% metal passivator (tolyltriazole derivative); 0.50% ashless extreme pressure anti-wear agent (trialkyl phosphate), 0.04% rust inhibitor (alkenyl succinic acid), 0.01% anti-foaming agent (polyacrylate type Foam Ban 3633E anti-foaming agent), 96.79% synthetic base oil (PAO 91.00% + polyol ester 5.79%).

[0054] The above components are mixed according to the above materials and their mass percentages to prepare a long-life screw air compressor oil composition.

[0055] In the prior art, antioxidants used in compressor oil compositions are mostly mixtures of phenolic antioxidants and amine antioxidants. Taking Examples 3 and 4 as examples, two compounding methods of antioxidants in the prior art are selected as comparative examples of the embodiments of the present invention, and the following comparative examples 1 to 2 are given.

[0056] Comparative Example 1

[0057] The difference from Example 3 is that the antioxidant is an alkyl diphenylamine and a phenolic antioxidant.

[0058] Comparative Example 2

[0059] The difference from Example 4 is that the antioxidant is an alkyl diphenylamine and a phenolic antioxidant.

[0060] The following performance tests were performed on the compressor oil compositions prepared in Examples 3 and 4 and Comparative Examples 1 to 2, and the performance test results shown in Table 1 were obtained.

[0061] Table 1 Performance test results

[0062]

[0063]

[0064] Combined with the performance test results in Table 1, we can see that the high-temperature oxidation resistance of the compressor oil composition prepared in Examples 3 to 4 is significantly improved, and the rotary oxygen bomb time is 2035min and 2596min respectively, and the oxidation induction period is doubled compared with the comparative example. The oxidation induction periods of Examples 3 and 4 are 51.94min and 49.71min respectively, while the rotary oxygen bomb time of Comparative Example 2 is relatively high, but the oxidation induction period is very short, only 16.54min. The inventor speculates that the reason may be: the phenolic antioxidant is used in Comparative Examples 1 to 2, which leads to a rapid decrease in the antioxidant performance of the oil during use, especially under high temperature conditions (greater than 100°C), the phenolic antioxidant will volatilize and decompose rapidly, and it will be consumed quickly, while the amine antioxidant has a high decomposition temperature, has excellent high-temperature oxidation resistance, can be retained in the lubricating oil for a long time, and is consumed very slowly, which plays a decisive role in extending the oil change period.

[0065] In addition, refer to Figure 1 As shown, Example 4 and Comparative Example 2 were subjected to a cycle test. From the figure, we found that after 16 cycles, the remaining content of the antioxidant in Example 4 was 40.4%, while after 8 cycles, the remaining content of the antioxidant in Comparative Example 2 was 0%. It can be seen that the antioxidant in the compressor oil composition decays slowly by using the compound of two amine antioxidants, has good retention, and its service life is significantly extended.

[0066] Through the performance test results and actual cycle times of Example 3 and Comparative Example 2, we can also find that: the test results of the rotating oxygen bomb of Example 3 and Comparative Example 2 are basically the same, but the actual cycle times of Example 3 are not less than 16 times, and the cycle times of Comparative Example 2 are only 8 times, and the actual service life of the oil product is only 8000 hours. There is a great difference between the two in terms of the retention of the residual content of the antioxidant. It can be seen that the rotating oxygen bomb of the new oil cannot represent the real service life of the oil product, and this method cannot simulate and predict the change of the residual content of the antioxidant in the oil product in actual application. The evaluation method of simulating the cycle times of the oil product and measuring the residual content of the antioxidant in the oil product is more scientific. Therefore, the evaluation method proposed by the present invention can scientifically predict the oil change cycle of the oil product.

[0067] The above are only preferred feasible embodiments of the present invention, and the protection scope of the present invention is not limited thereto. Various modifications or applications made according to the above embodiments are within the protection scope of this technical solution.

[0068] Although the specific embodiments of the present invention have been described in detail, it will be understood by those skilled in the art. According to all the teachings disclosed, various modifications and replacements can be made to those details, and these changes are all within the protection scope of the present invention. The full scope of the present invention is given by the attached claims and any equivalents thereof.

Claims

1. A long-life screw air compressor oil composition, characterized in that: The invention comprises the following components by mass percentage: 1.2% to 4% antioxidant, 0.02% to 0.1% metal passivator, 0.02% to 0.5% ashless extreme pressure anti-wear agent, 0.01% to 0.1% rust preventive, 0.01% to 0.03% anti-foaming agent, and the remainder is synthetic base oil.

2. The long-life screw air compressor oil composition according to claim 1, characterized in that: The antioxidant includes an alkylated diphenylamine type antioxidant; The alkylated diphenylamine antioxidant is selected from butyl octyl diphenylamine or dinonyl diphenylamine.

3. The long-life screw air compressor oil composition according to claim 2, characterized in that: The antioxidant also includes: naphthylamine antioxidant; The naphthylamine antioxidant is selected from N-phenyl-α-naphthylamine or alkyl-phenyl-α-naphthylamine.

4. The long-life screw air compressor oil composition according to claim 1, characterized in that: The metal deactivator is selected from one or more of benzotriazole derivatives, methylbenzotriazole derivatives or N,N-dialkylaminomethylenebenzotriazole derivatives.

5. The long-life screw air compressor oil composition according to claim 1, characterized in that: The ashless extreme pressure anti-wear agent is selected from one of alkyl phosphates, phosphites or thiosulfates.

6. The long-life screw air compressor oil composition according to claim 1, characterized in that: The rust inhibitor is selected from one or more of alkenyl succinic acid, alkenyl succinic acid half ester or barium dinonylnaphthalene sulfonate.

7. The long-life screw air compressor oil composition according to claim 1, characterized in that: The antifoaming agent is selected from silicone antifoaming agent or polyacrylate antifoaming agent.

8. The long-life screw air compressor oil composition according to claim 1, characterized in that: The synthetic base oil is selected from one or more of olefins, alkylnaphthalenes or polyol esters.

9. A method for preparing the long-life screw air compressor oil composition according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: S1. Add synthetic base oil according to mass percentage and raise the temperature to 45±5℃ under stirring; S2. Under stirring conditions, antioxidant, metal passivator, ashless extreme pressure anti-wear agent, rust inhibitor and anti-foaming agent are added in sequence to the heated synthetic base oil in S1, and the mixture is heated and mixed to obtain a long-life screw air compressor oil composition.

10. A method for evaluating the long-life screw air compressor oil composition according to any one of claims 1 to 8, characterized in that: The method uses a combination of rotating oxygen bomb method and linear voltammetry to evaluate the composition.

11. The method for evaluating a long-life screw air compressor oil composition according to claim 10, characterized in that: The method comprises: The composition is subjected to a cyclic test within a set time period using a rotating oxygen bomb method; The cyclic test includes: taking 9% of the composition sample each time, using linear voltammetry to evaluate the remaining service life of the composition sample to test the remaining content of the antioxidant in the composition sample, and adding an equal amount of the composition sample at the same time to start the next cycle until the linear voltammetry result shows that the remaining content of the antioxidant is zero, and the test ends.

12. The method for evaluating a long-life screw air compressor oil composition according to claim 10 or 11, characterized in that: The long-life screw air compressor oil composition has a cycle number of not less than 16 times and a service life of not less than 16,000 hours.

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