Ionic liquid, preparation method and application thereof and lubricating oil

Abstract

The invention provides ionic liquid, a preparation method and application thereof and lubricating oil, and relates to the technical field of lubricating oil additives. The ionic liquid provided by the invention contains dication, so that the ionic liquid shows higher thermal stability than the corresponding conventional ionic liquid; the ionic liquid provided by the invention contains N, O and P heteroatoms, and can be effectively adsorbed with the metal surface of a friction pair, and a chemical reaction film is formed in the friction process, so that the effects of reducing friction and resisting wear are achieved; the dication of the ionic liquid provided by the invention has no substituent group, and the two cations are far away from each other, so that the steric hindrance of the structure is small, the effective adsorption of the ionic liquid on the surface of a friction pair is enhanced, and the lubricating effect is further improved; in addition, the ionic liquid provided by the invention has a long-chain alkyl substituent, so that the ionic liquid has good oil solubility. The ionic liquid provided by the invention is used as a lubricating oil additive, and has excellent antifriction and antiwear properties while having excellent thermal stability.

Description

Technical Field

[0001] The invention relates to the technical field of lubricating oil additives, and in particular to an ionic liquid, a preparation method and application thereof, and lubricating oil. Background Art

[0002] Oil-soluble ionic liquids have been widely studied and applied as lubricating additives due to their excellent lubrication, physicochemical properties, corrosion resistance, simple synthesis, and low environmental pollution, which has greatly promoted the technological development of lubricating oils. As one of the important indicators of lubricating oil additives, the thermal stability of lubricating oil additives determines the application temperature range of lubricating oil products. In order to further improve the thermal stability of oil-soluble additives, dicationic ionic liquids were designed and synthesized. However, compared with the corresponding common monocationic ionic liquids, although the thermal stability of dicationic ionic liquids has been improved, their friction reduction and anti-wear properties have been reduced. Summary of the invention

[0003] In view of this, the object of the present invention is to provide an ionic liquid and its preparation method and application and lubricating oil. The ionic liquid provided by the present invention has excellent thermal stability as a lubricating oil additive and also has good friction reduction and anti-wear performance.

[0004] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0005] The present invention provides an ionic liquid having a structure shown in Formula I:

[0006]

[0007] In Formula I, R is a saturated alkane having 10 to 16 carbon atoms, and X - Having a structure shown in any one of formulas II to IV:

[0008]

[0009] In formulae II to IV, R1 is a saturated alkane having 5 to 11 carbon atoms, R2 is a saturated alkane having 6 to 12 carbon atoms, and R3 is a saturated alkane, an alkyl-substituted aryl group or an alkyl-substituted ester group.

[0010] Preferably, the R is a saturated straight-chain alkane, wherein the saturated straight-chain alkane is -C 10 H 21 , -C 12 H 25 , -C 14 H 29 or -C 16 H 33 .

[0011] Preferably, the structure represented by formula II is hexanoate, octanoate, isooctanoate, nonanoate, decanoate or dodecanoate.

[0012] Preferably, R2 is hexyl, octyl, isooctyl or dodecyl.

[0013] Preferably, R3 is dodecyl, dodecylphenyl or has a structure shown in Formula V:

[0014]

[0015] The present invention provides a method for preparing the ionic liquid described in the above technical solution, comprising the following steps:

[0016] The alkylamine dipropylene diamine and an organic acid are mixed and neutralized to obtain the ionic liquid; the alkylamine dipropylene diamine has a structure shown in formula VI, and the acid radical ion in the organic acid has a structure shown in any one of formulas II to IV;

[0017]

[0018] Preferably, the molar ratio of the alkylamine dipropylene diamine to the organic acid is 1:2-3; the temperature of the neutralization reaction is 60-120° C., the time is 12-96 hours, and the neutralization reaction is carried out under a nitrogen atmosphere.

[0019] The present invention provides the use of the ionic liquid described in the above technical solution as an additive in lubricating oil.

[0020] The present invention also provides a lubricating oil, comprising a base oil and an additive, wherein the additive is the ionic liquid described in the above technical solution.

[0021] Preferably, the mass content of the additive in the lubricating oil is 0.1-10%.

[0022] The present invention provides an ionic liquid having a structure shown in Formula I. The ionic liquid provided by the present invention contains a double cation, and thus exhibits higher thermal stability than the corresponding conventional ionic liquid; the ionic liquid provided by the present invention contains N, O, and P heteroatoms, which can be effectively adsorbed on the metal surface of the friction pair, and a chemical reaction film is formed during the friction process to achieve the effect of reducing friction and resisting wear; and the double cation of the ionic liquid provided by the present invention has no substituent, and the two cations are far apart, so that the steric hindrance of the structure is small, thereby enhancing the effective adsorption of the ionic liquid on the friction pair surface, thereby improving the lubrication effect; in addition, the ionic liquid provided by the present invention has a long-chain alkyl substituent, and thus has good oil solubility. Therefore, the ionic liquid provided by the present invention has excellent thermal stability, excellent friction reduction and anti-wear performance, and good oil solubility.

[0023] The present invention provides a method for preparing the ionic liquid described in the above technical solution, which has a simple process and is convenient for large-scale production. DETAILED DESCRIPTION

[0024] The present invention provides an ionic liquid having a structure shown in Formula I:

[0025]

[0026] In Formula I, R is a saturated alkane having 10 to 16 carbon atoms, and X - Having a structure shown in any one of formulas II to IV:

[0027]

[0028] In formulae II to IV, R1 is a saturated alkane having 5 to 11 carbon atoms, R2 is a saturated alkane having 6 to 12 carbon atoms, and R3 is a saturated alkane, an alkyl-substituted aryl group or an alkyl-substituted ester group.

[0029] In the present invention, in Formula I, R is preferably a saturated straight-chain alkane, and the saturated straight-chain alkane is preferably -C 10 H 21 , -C 12 H 25 , -C 14 H 29 or -C 16 H 33 , more preferably -C 12 H 25 or -C 14 H 29 .

[0030] In the present invention, the structure shown in Formula II is preferably hexanoate, octanoate, isooctanoate, nonanoate, decanoate or dodecanoate, more preferably octanoate, isooctanoate or dodecanoate, and the structural formulas of the octanoate, isooctanoate and dodecanoate are as follows:

[0031]

[0032] In the present invention, in Formula III, R2 is preferably hexyl, octyl, isooctyl or dodecyl, more preferably octyl or isooctyl; when R2 is octyl or isooctyl, the structures shown in Formula III are as follows:

[0033]

[0034] In the present invention, in Formula IV, R3 is preferably dodecyl, dodecylphenyl or has a structure shown in Formula V, more preferably has a structure shown in Formula V (in the structure shown in Formula V, * represents a connection site):

[0035]

[0036] When R3 has the structure shown in formula V, the structure shown in formula IV is as follows:

[0037]

[0038] The present invention provides a method for preparing the ionic liquid described in the above technical solution, comprising the following steps:

[0039] The alkylamine dipropylene diamine and an organic acid are mixed and neutralized to obtain the ionic liquid; the alkylamine dipropylene diamine has a structure shown in formula VI, and the acid radical ion in the organic acid has a structure shown in any one of formulas II to IV.

[0040]

[0041] In the present invention, unless otherwise specified, all raw materials involved are commercially available products in the art.

[0042] In the present invention, R in the structure shown in Formula VI is consistent with R in the structure shown in Formula I.

[0043] In the present invention, the acid radical ion in the organic acid has a structure shown in any one of formulas II to IV.

[0044] When the acid radical ion in the organic acid has a structure shown in Formula II, the organic acid is preferably hexanoic acid, octanoic acid, isooctanoic acid (ie, 2-ethylhexanoic acid), nonanoic acid, decanoic acid or dodecanoic acid.

[0045] When the acid radical ion in the organic acid has a structure shown in Formula III, the organic acid is preferably dihexyl phosphate, dioctyl phosphate, diisooctyl phosphate or dilauryl phosphate. When the acid radical ion in the organic acid has a structure shown in Formula III, the present invention has no special requirements on the source of the organic acid, and it can be prepared using commercially available products or a preparation method well known to those skilled in the art. In an embodiment of the present invention, when the acid radical ion in the organic acid has a structure shown in Formula III, the organic acid can be prepared by the following method:

[0046] Under a nitrogen atmosphere, phosphorus pentoxide (0.1 mol) and alcohol (0.4 mol) were added to a 500 mL two-necked flask equipped with a magnet, and heated and stirred at 80°C for 12 h. After the reaction was completed and the room temperature was restored to 500 mL, acetonitrile was added to the two-necked flask, stirred for 0.5 h, and then poured into a separatory funnel, allowed to stand for separation, the lower layer of liquid was collected, and dried to obtain the organic acid.

[0047] In the present invention, the structural formula of the alcohol is HO-R2 (R2 is consistent with R2 in formula III), and the alcohol is preferably hexanol, octanol (i.e., n-octanol), isooctyl alcohol (i.e., 2-ethylhexanol) or lauryl alcohol, and dihexyl phosphate, dioctyl phosphate, diisooctyl phosphate or dilauric phosphate are obtained accordingly.

[0048] When the acid radical ion in the organic acid has a structure shown in Formula IV, the organic acid is preferably dodecylsulfonic acid, dodecylbenzenesulfonic acid or docusate. In an embodiment of the present invention, the docusate is prepared by the following method:

[0049] Hydrochloric acid (1 mol / L, 100 mL) was added dropwise into 200 mL of deionized water containing docusate sodium (0.1 mol), stirred for 0.5 h, and then the water was dried by spin drying to obtain the target product docusate acid; the structural formula of the docusate sodium is as follows:

[0050]

[0051] In the present invention, the molar ratio of the alkylamine dipropylene diamine to the organic acid is preferably 1:2 to 3, more preferably 1:2 to 2.5. In the present invention, the temperature of the neutralization reaction is preferably 60 to 120°C, more preferably 80 to 100°C, and the time is preferably 12 to 96 hours, more preferably 24 to 72 hours; the neutralization reaction is preferably carried out under a nitrogen atmosphere and stirring. In the present invention, the alkylamine dipropylene diamine and the organic acid are preferably added to the reaction vessel, and then heated under a nitrogen atmosphere to carry out the neutralization reaction.

[0052] After the neutralization reaction is completed, the obtained reaction product is cooled to room temperature to obtain the ionic liquid.

[0053] The present invention provides the use of the ionic liquid described in the above technical solution as an additive in lubricating oil. The ionic liquid provided by the present invention has excellent thermal stability and excellent friction reduction and anti-wear properties, as well as good oil solubility. The ionic liquid is applied to lubricating oil as an additive. During the friction process, the two cations of the ionic liquid are adsorbed on the surface of the friction pair, and the long-chain alkyl substituent "floats" in the lubricating oil, like water grass. Therefore, the ionic liquid is also named "grass-type" ionic liquid in the embodiment of the present invention.

[0054] The present invention also provides a lubricating oil, comprising a base oil and an additive, wherein the additive is the ionic liquid described in the above technical solution. The present invention has no special requirements for the base oil, and the base oil familiar to those skilled in the art can be used, such as A51, NP451, PAO2, PAO10, PAO40, 150N, 150SN, 150BS, Yubase6, 500N, 500SN. In the present invention, the mass content of the additive in the lubricating oil is preferably 0.1-10%, and can be 1%, 2%, 3% or 4%. The present invention preferably dissolves the additive in the base oil under heating conditions to obtain the lubricating oil; the heating temperature is preferably 80°C.

[0055] In order to further illustrate the present invention, the ionic liquid and its preparation method and application and lubricating oil provided by the present invention are described in detail below in combination with examples, but they should not be construed as limiting the scope of protection of the present invention.

[0056] Example 1

[0057] Preparation of "grass-type" ionic liquid: Under nitrogen atmosphere, 8.89g (0.03mol) of laurylamine dipropylene diamine and 19.32 (0.06mol) of diisooctyl phosphate were added to a 250mL round-bottom flask and reacted with magnetic stirring at 80°C for 24h. After the reaction was completed, it was cooled to room temperature to obtain a "grass-type" ionic liquid, which was recorded as NP2N-12; the structural formula of diisooctyl phosphate is as follows:

[0058]

[0059] Example 2

[0060] Preparation of "grass-type" ionic liquid: Under nitrogen atmosphere, 8.89 g (0.03 mol) of laurylamine dipropylene diamine and 8.65 g (0.06 mol) of 2-ethylhexanoic acid were added to a 250 mL round-bottom flask and reacted with magnetic stirring at 80 ° C for 24 h. After the reaction was completed, it was cooled to room temperature to obtain a "grass-type" ionic liquid, which was recorded as NO2N-12.

[0061] Example 3

[0062] Preparation of docusate acid: hydrochloric acid (1 mol / L, 100 mL) was added dropwise into 200 mL of deionized water containing docusate sodium (0.1 mol), stirred for 0.5 h, and then the water was dried by spin drying to obtain docusate acid; wherein the structural formula of docusate sodium is as follows:

[0063]

[0064] Preparation of "grass-type" ionic liquid: Under nitrogen atmosphere, 8.89 g (0.03 mol) of laurylamine dipropylene diamine and 25.35 g (0.06 mol) of docusate were added to a 250 mL round-bottom flask and reacted with magnetic stirring at 80 ° C for 24 h. After the reaction was completed, it was cooled to room temperature to obtain a "grass-type" ionic liquid, which was recorded as NS2N-12.

[0065] The thermal stability of the "grass-type" ionic liquids prepared in the examples, i.e., NP2N-12 in Example 1, NO2N-12 in Example 2, and NS2N-12 in Example 3, was measured using a thermogravimetric analyzer, with the test temperature ranging from room temperature to 600°C, and the heating rate being 10°C / min. The test results showed that the decomposition temperatures of the ionic liquids were 283.3°C for NP2N-12, 233.6°C for NO2N-12, and 289.7°C for NS2N-12.

[0066] Example 4

[0067] The NP2N-12 in Example 1 was used as an additive and dissolved in 20 mL of PAO10 base oil at mass fractions (additive / (additive+base oil)) of 0%, 1%, 2%, 3% and 4%, respectively, and heated at 80°C for 30 min to fully dissolve, thereby obtaining a lubricating oil.

[0068] The friction performance test was carried out on each lubricating oil in Example 4, and the test conditions were: load 200N, temperature 25°C, frequency 25Hz, amplitude 1mm, and experimental time 30min; the upper test ball was an AISI 52100 steel ball with a diameter of 10mm; in the steel / steel friction pair, the lower sample was an AISI 52100 steel block with a diameter of 24mm and a thickness of 7.9mm, and a hardness of 700-750HV; the wear volume of the lower sample was measured by a fully automatic true color confocal microscope DCM8, and the test results are shown in Table 1.

[0069] Table 1 Friction performance test results of each lubricating oil in Example 4

[0070] sample Average friction coefficient <![CDATA[Average wear volume / μm 3 > PAO10 0.238 1132139 PAO10+1wt%NP2N-12 0.097 55245 PAO10+2wt%NP2N-12 0.097 44554 PAO10+3wt%NP2N-12 0.097 54427 PAO10+4wt%NP2N-12 0.093 51406

[0071] Example 5

[0072] The NO2N-12 in Example 2 and the NS2N-12 in Example 3 were respectively dissolved in PAO10 base oil as additives at a mass fraction (additive / (additive+base oil)) of 2%, and heated at 80°C for 30 minutes to fully dissolve, thereby obtaining lubricating oil.

[0073] The friction performance test was carried out on the lubricating oil in Example 5. The test conditions were the same as those in Example 4. The test results are shown in Table 2.

[0074] Table 2 Friction performance test results of lubricating oil in Example 5

[0075] sample Average friction coefficient <![CDATA[Average wear volume / μm 3 > PAO10+2wt%NO2N-12 0.209 76821 PAO10+2wt%NS2N-12 0.179 106351

[0076] Comparative Example

[0077] Preparation of ionic liquid: 5.56 g (0.03 mol) of dodecylamine and 9.67 g (0.03 mol) of diisooctyl phosphate (the structural formula is the same as that in Example 1) were added to a 250 mL round-bottom flask and reacted at 80° C. with magnetic stirring for 24 h. After the reaction was completed, the mixture was cooled to room temperature to obtain an ionic liquid, which was recorded as NP-12.

[0078] The decomposition temperature of NP-12 is 267.3°C.

[0079] 2 wt% (additive / (additive+base oil)) of NP-12 was added to PAO10 to obtain a lubricating oil. The friction performance test of the obtained lubricating oil was carried out under the same test conditions as in Example 4. Test results: The average friction coefficient of the lubricating oil obtained in the comparative example was 0.093, and the average wear volume was 54743 μm 3 .

[0080] Compared with the ionic liquid of the comparative example, the decomposition temperature of the "grass-type" ionic liquid prepared in the embodiment of the present invention is higher (NP2N-12: 283.3°C, NP-12: 267.3°C), the friction reduction performance is equivalent (NP2N-12: average friction coefficient 0.097, NP-12: average friction coefficient 0.093), but the anti-wear performance is significantly better than that of the comparative example (NP2N-12: wear volume 44554 μm 3 NP-12: wear volume 54743 μm 3 ).

[0081] It can be seen from the above examples that the ionic liquid provided by the present invention as a lubricating oil additive has higher thermal stability while maintaining excellent friction reduction and anti-wear performance.

[0082] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. An ionic liquid, characterized in that It has the structure shown in formula I: In Formula I, R is a saturated alkane having 10 to 16 carbon atoms, and X - Having a structure shown in any one of formulas II to IV: In formulae II to IV, R1 is a saturated alkane having 5 to 11 carbon atoms, R2 is a saturated alkane having 6 to 12 carbon atoms, and R3 is a saturated alkane, an alkyl-substituted aryl group or an alkyl-substituted ester group.

2. The ionic liquid according to claim 1, characterized in that The R is a saturated straight-chain alkane, and the saturated straight-chain alkane is -C 10 H 21 , -C 12 H 25 , -C 14 H 29 or -C 16 H 33 .

3. The ionic liquid according to claim 1, characterized in that The structure shown in formula II is hexanoate, octanoate, isooctanoate, nonanoate, decanoate or dodecanoate.

4. The ionic liquid according to claim 1, characterized in that The R2 is hexyl, octyl, isooctyl or dodecyl.

5. The ionic liquid according to claim 1, characterized in that The R3 is dodecyl, dodecylphenyl or has a structure shown in Formula V:

6. The method for preparing the ionic liquid according to any one of claims 1 to 5, characterized in that: The following steps are involved: The alkylamine dipropylene diamine and an organic acid are mixed and neutralized to obtain the ionic liquid; the alkylamine dipropylene diamine has a structure shown in formula VI, and the acid radical ion in the organic acid has a structure shown in any one of formulas II to IV; 7. The preparation method according to claim 6, characterized in that: The molar ratio of the alkylamine dipropylene diamine to the organic acid is 1:2-3; the temperature of the neutralization reaction is 60-120° C., the time is 12-96 hours, and the neutralization reaction is carried out under a nitrogen atmosphere.

8. Use of the ionic liquid according to any one of claims 1 to 5 as an additive in lubricating oil.

9. A lubricating oil, characterized in that: The invention comprises a base oil and an additive, wherein the additive is the ionic liquid according to any one of claims 1 to 5.

10. The lubricating oil according to claim 9, characterized in that The mass content of the additive in the lubricating oil is 0.1-10%.

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