RU2703733C2 - Lubricating oil composition for sliding guide surface - Google Patents

Abstract

FIELD: chemistry.SUBSTANCE: lubricating oil composition contains base oil, wherein base oil is base oil belonging to group III, and/or base oil belonging to group IV, in categories of API base oils; phosphonate represented by formula (1), in which Rdenotes a saturated or unsaturated alkyl group having 12–22 carbon atoms, and Rdenotes a saturated or unsaturated alkyl group having 1–18 carbon atoms and a fatty acid represented by formula (2), in which Rdenotes a saturated or unsaturated alkyl group having 7–17 carbon atoms.(1), RCOOH (2).EFFECT: present invention relates to lubricating oil composition for guide sliding surface, which has demonstrated excellent characteristics of low friction coefficient and extreme-pressure characteristics so as to ensure high accuracy of processing on machine.3 cl, 3 tbl

Description

Field of Invention

The present invention relates to a lubricating oil composition that meets the lubrication requirements of a sliding guide surface of a machine tool or the like.

BACKGROUND OF THE INVENTION

In order to carry out high-precision machining with a machine, the extreme accuracy of positioning the machine's running shaft is important, and in some cases, micron level accuracy is required. At the same time, lubricating oils are used because the positioning accuracy may deteriorate due to the friction resistance created on the guide surface of the machine having the sliding guide surface, and it is necessary that the lubricating oil used on this guide surface exhibit low friction.

In addition, the lubricating oils used in the machines can also be used to lubricate gears and the like in addition to the guide surfaces as described above, and in such cases, bearing characteristics are also required as an important feature.

Therefore, since smooth movement and high precision of the guide surfaces is required, various friction reducing agents are mixed into the lubricating oils used on the guide surfaces. For example, JP 11-505283 describes that attempts have been made to achieve low friction and acceptable slip characteristics by using a combination of acidic phosphoric acid esters and phosphonic acid esters.

SUMMARY OF THE INVENTION

Traditional lubricating oil compositions have yet to achieve satisfactory lubricating characteristics for machine tools that require high precision machining, and the aim of the present invention, which was developed taking into account these circumstances, is to obtain a lubricating oil composition having further improved friction and extreme pressure characteristics.

As a result of various studies and studies carried out to reduce friction and achieve good extreme pressure characteristics, as described above, it was found that in cases where a combination of a phosphonic acid ester and a fatty acid were used, a lower friction coefficient and a higher bearing capacity than in the case when any of these additives was used separately, and the present invention is based on these findings.

The present invention provides a lubricating oil composition for a sliding guide surface that contains any base oil of group I, base oil of group II, base oil of group III or base oil of group IV in the API base oil categories (American Petroleum Institute - American Institute oil), or a mixture thereof as a base oil, and which is obtained by adding to this base oil a combination of phosphonate (phosphonic acid ester) and a medium or higher fatty acid.

In addition, a more preferred base oil is a group III base oil, which is a highly refined mineral oil or a base oil, which is a synthetic group IV oil in the API base oil categories, or a mixture thereof.

The lubricating oil composition of the present invention can exhibit excellent friction characteristics and excellent bearing capacity on a sliding guide surface of a machine tool or the like, and can be effectively used as a lubricating oil composition for a sliding guide surface.

Detailed Description of the Invention

The base oil from group I to group IV in the API base oil categories or a mixture thereof is used as the lubricant base oil of the present invention.

An example of a Group I base oil is paraffin-based mineral oil obtained by treating a distillate of a lubricating oil obtained by atmospheric distillation of a crude oil by an appropriate combination of refining operations, for example, selective solvent refining, hydrotreating and dewaxing.

The viscosity index values are suitable from 80 to 120 and preferably from 95 to 110. The kinematic viscosity is preferably in the range from 2 to 680 mm ² / s and more preferably from 8 to 220 mm ² / s at 40 ° C. In addition, a total sulfur content of more than 300 ppm and less than 700 ppm and preferably less than 500 ppm is suitable. A total nitrogen content of less than 50 ppm and preferably less than 25 ppm is suitable. In addition, the aniline point should be in the range from 80 to 150 ° C and preferably from 90 to 120 ° C.

An example of a Group II base oil is paraffin-based mineral oil obtained by treating a distillate of a lubricating oil obtained by atmospheric distillation of a crude oil corresponding to a combination of refining operations, for example, hydrocracking and dewaxing.

The viscosity of these base oils is not particularly limited, but a viscosity index of from 80 to less than 120 and preferably from 100 to less than 120 is suitable. The kinematic viscosity is preferably in the range from 2 to 680 mm ² / s and more preferably from 8 to 220 mm ² / s at 40 ° C.

In addition, a total sulfur content of not more than 300 ppm, preferably not more than 200 ppm, and more preferably not more than 10 ppm, is suitable. A total nitrogen content of less than 10 ppm and preferably less than 1 is suitable. ppm In addition, an aniline point of from 80 to 150 ° C, and preferably from 100 to 135 ° C, is suitable.

In addition, a Group II base oil that has been purified using a hydrotreating process, such as that used by Gulf Oil, having a suitable total sulfur content of less than 10 ppm and a suitable aromatic content of 5% or less, may provide an advantage consisting of in its use in the present invention.

Examples of group III base oils include paraffin-based mineral oil obtained by treating a distillate of a lubricating oil obtained by atmospheric distillation of a crude oil to a high degree of hydrotreatment, as well as a base oil obtained by refining a wax obtained from a dewaxing process using an isodeparaffinization process in which the conversion and dewaxing are carried out, or the base oil that has been purified using a wax isomerization process, is used Mobil Oil

The viscosity of these base oils of group III is not particularly limited, but the viscosity index should be from 120 to 180 and preferably from 130 to 150. The kinematic viscosity is preferably in the range from 2 to 680 mm ² / s and more preferably from 8 to 220 mm ² / s at 40 ° C. In addition, a total sulfur content of 300 ppm or less, and preferably 10 ppm or less, is suitable. Suitable is a total nitrogen content of 10 ppm or less, and preferably 1 ppm or less. In addition, an aniline point of from 80 to 150 ° C, and preferably from 110 to 135 ° C, is suitable.

In addition, the GLC (GTL) base oil belonging to Group III (gas-liquid conversion) obtained by the Fischer-Tropsch synthesis, which is a method of converting natural gas to liquid fuel, has a significantly lower sulfur content and aromatic compounds and significantly higher the proportion of paraffin than mineral oil-refined base oil and therefore exhibits excellent oxidative stability and extremely low evaporation losses and can be successfully evaporated lzovano as the base oil in the present invention.

The viscosity properties of this GFA base oil are not particularly limited, but the viscosity index is typically from 130 to 180 and more preferably from 140 to 175. In addition, the kinematic viscosity is suitable in the range from 2 to 680 mm ² / s and more preferably from 5 to 120 mm ² / s. In addition, the total sulfur content, as a rule, is less than 10 ppm, and the total nitrogen content, as a rule, is less than 1 ppm. An example of this type of GFA base oil is SHELL XHVI ™.

Polyolefins are an example of a group IV base oil, and they contain polymers from a variety of olefins and their hydrogenation products. Any type of olefin may be used, but their examples are ethylene, propylene, butene and α-olefins having 5 or more carbon atoms. In the production of polyolefins, one olefin alone or a combination of two or more types thereof can be used. Particularly preferred are polyolefins, known as PAO poly-α-olefins.

The viscosity of these polyolefins is not particularly limited, but the kinematic viscosity is preferably in the range from 2 to 680 mm ² / s and more preferably from 8 to 220 mm ² / s at 40 ° C.

The phosphonate mentioned above is represented below by formula 1

(1).

(one).

In the above formula 1, R1 represents a saturated or unsaturated alkyl group having 12-22 carbon atoms and preferably 12-18 carbon atoms. R ₂ represents a saturated or unsaturated alkyl group having 1-18 carbon atoms. These alkyl groups are often linear, but may be branched.

Examples of the phosphonate of this type are dimetildodetsil phosphonate dimethyltridecyl phosphonate dimetiltetradetsil phosphonate dimetilpentadetsil phosphonate dimetilgeksadetsil phosphonate dimetilgeptadetsil phosphonate dimetiloktadetsil phosphonate dimetilnonadetsil phosphonate dimetilikosil phosphonate tridodetsil phosphonate tritridetsil phosphonate tritetradetsil phosphonate tripentadetsil phosphonate trigeksadetsil phosphonate trigeptadetsil phosphonate, trioctadecyl phosphonate (tristearyl phosphite: tautomer) and trioleyl phosphonate.

This type of phosphonate should be used in an amount of the order of not less than 0.2 wt.%, But less than 2 wt.%, And preferably not less than 0.5 wt.%. and not more than 1.5% wt. in relation to the total amount of the lubricating oil composition.

The above fatty acid is represented by formula 2 below

R ₃ COOH (2).

In the above formula 2, R3 represents a saturated or unsaturated alkyl group having 7-17 carbon atoms.

Examples of fatty acids of this type are caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, isostearic acid, oleic acid, linoleic acid and linolenic acid.

This type of fatty acid should be used in an amount of the order of not less than 0.03% wt., But less than 1% wt., And preferably not less than 0.1% wt. and not more than 0.7% wt. in relation to the total amount of the lubricating oil composition.

Metal deactivators, antiwear additives and the like can also be added to this lubricating oil composition. Examples of metal deactivators are thiadiazole derivatives, for example, 2,5-bis (alkyldithio) -1,3,4-thiadiazole compounds, for example 2,5-bis (heptyldithio) -1,3,4-thiadiazole, 2,5-bis (nonyldithio) -1,3,4-thiadiazole, 2,5-bis (dodecyldithio) -1,3,4-thiadiazole and 2,5-bis (octadecyldithio) -1,3,4-thiadiazole; compounds of 2,5-bis (N, N-dialkyldithiocarbamyl) -1,3,4-thiadiazole, for example 2,5-bis (N, N-diethyldithiocarbamyl) -1,3,4-thiadiazole, 2,5-bis (N, N-dibutyldithiocarbamyl) -1,3,4-thiadiazole and 2,5-bis (N, N-dioctyldithiocarbamyl) -1,3,4-thiadiazole; and 2-N, N-dialkyldithiocarbamyl-5-mercapto-1,3,4-thiadiazole compounds, for example, 2-N, N-dibutyldithiocarbamyl-5-mercapto-1,3,4-thiadiazole and 2-N, N- dioctyldithiocarbamyl-5-mercapto-1,3,4-thiadiazole. In some cases, benzotriazole or a benzotriazole derivative, benzimidazole or a benzimidazole derivative, imidazole or an imidazole derivative, benzothiazole or a benzothiazole derivative, benzoxazole derivative, triazole derivative or the like can be used. In the lubricating oil composition, one or more of these metal deactivators can be used in an amount of about 0.01-0.5% by weight.

Examples of antiwear additives are diisobutyl disulfide, diisobutyl trisulphide, di-tert-butyl trisulphide, dioctyl trisulphide, di-tert-nonyl trisulphide, di-tert-benzyl trisulphide and other polysulphides. You can also use sulfonated olefin, sulfurized oil or fat, or the like. In the lubricating oil composition, one or more of these sulfur-based antiwear additives can be used in an amount of about 0.1 to 3% by weight.

In addition, these metal deactivators and anti-wear additives can be used individually or in appropriate combinations, and when used in combination, a low friction coefficient can be achieved, better abrasion resistance and extreme pressure properties can be achieved, while the guiding surface slip can be effectively lubricated in aggressive conditions.

If necessary, antioxidants can be added to the lubricating oil composition of the present invention, for example, amine and phenol based antioxidants, corrosion inhibitors, structure stabilizers, viscosity modifiers, dispersing agents, lowering pour points, depressants, antifoam agents and other known additives .

The viscosity class of the lubricating oil composition for the sliding guide surface described above should be VG22 to VG220, and preferably VG32 to VG68 in accordance with ISO viscosity classes.

The lubricating oil composition for the sliding guide surface of the present invention will now be described with specific concepts by way of working examples and comparative examples, however, the present invention is in no way limited to these examples.

Examples

The following materials have been prepared for working examples and comparative examples.

Base oils

Base oil 1: GLC base oil (gas-liquid conversion) belonging to group III (characteristics: kinematic viscosity at 100 ° C: 7.579 mm ² / s, kinematic viscosity at 40 ° C: 43.69 mm ² / s, viscosity index (VI ): 141, density at 15 ° C: 0.8284) (Shell XHVI-8 manufactured by Royal Dutch Shell)

Base oil 2: refined mineral oil belonging to group III (characteristics: kinematic viscosity at 100 ° C: 7.545 mm ² / s, kinematic viscosity at 40 ° C: 45.50 mm ² / s, viscosity index (VI): 132 , density at 15 ° C: 0.8453) (Yu-Base 8 manufactured by SK Innovation)

Base oil 3: PAO (poly-α-olefin) belonging to group IV (characteristics: kinematic viscosity at 100 ° C: 7.741 mm ² / s, kinematic viscosity at 40 ° C: 46.25 mm ² / s, viscosity index (VI): 136, density at 15 ° C: 0.8322) (Durasyn 168 manufactured by Ineos Oligomers)

Base oil 4: refined mineral oil belonging to group II (characteristics: kinematic viscosity at 100 ° C: 5,352 mm ² / s, kinematic viscosity at 40 ° C: 31,10 mm ² / s, viscosity index (VI): 105 density at 15 ° C: 0.8627)

Base oil 5: refined mineral oil belonging to group II (characteristics: kinematic viscosity at 100 ° C: 9.490 mm ² / s, kinematic viscosity at 40 ° C: 73.66 mm ² / s, viscosity index (VI): 106 density at 15 ° C: 0.8683)

Base oil 6: refined mineral oil belonging to group I (characteristics: kinematic viscosity at 100 ° C: 4.628 mm ² / s, kinematic viscosity at 40 ° C: 24.32 mm ² / s, viscosity index (VI): 106 density at 15 ° C: 0.8625)

Base oil 7: refined mineral oil belonging to group I (characteristics: kinematic viscosity at 100 ° C: 7.446 mm ² / s, kinematic viscosity at 40 ° C: 51.37 mm ² / s, viscosity index (VI): 106 density at 15 ° C: 0.8736)

Additives

Additive 1-1: Dimethyl octadecyl phosphonate

Additive 1-2: Tridodecyl Phosphonate

Additive 1-3: Tristearylphosphite

Additive 2-1: Caprylic acid

Additive 2-2: Lauric acid

Additive 2-3: Stearic Acid

Additive 2-4: Oleic acid

Additive 3: Diethylbenzylphosphonate

Additive 4: Behenic Acid

Supplement 5: Thiadiazole

Additive 6: Di-tert-dodecyl trisulfide

Working examples 1-16 and comparative examples 1-12

Lubricating oil compositions for the sliding guide surface of working examples 1-16 and comparative examples 1-12 were prepared using the materials mentioned above, according to the compositions shown in tables 1-3 below. The number of mixed components are presented as% wt.

Test

Friction Coefficient: Pendulum Type Friction Coefficient Test

The friction coefficients of the lubricating oil compositions of working examples 1-16 and comparative examples 1-12 were measured using a Soda pendulum oil tester, manufactured by Shinko Engineering Co., Ltd. In this test, the test oil was applied to the wear part, which is the support head of the pendulum, the pendulum was oscillated, and the friction coefficient was determined based on the damping of the oscillations. The test was carried out at room temperature (25 ° C).

The evaluation of the test was carried out in accordance with the following criteria:

A friction coefficient of 0.110 or less was recognized as ○ (tested).

A coefficient of friction of more than 0.110 was recognized × (failed the test).

Flash point

The flash points of the samples of working examples 1-16 and comparative examples 1-12 were measured five times in accordance with JIS K2265-4 using an open type automatic device for determining the Cleveland flash point, and the average value was determined by rounding to 1 digit after the decimal place. The thermometer used was Thermometer No. 32 according to the JIS B7410 (COC) specification.

The evaluation of the test was carried out in accordance with the following criteria:

A flash point of 220 ° C or higher was recognized as ○ (tested).

A flash point of less than 220 ° C was recognized × (failed test).

Load Test: (EP) Shell Four-Ball Friction Test (CWMT) Test

Working examples 1 and 12 and comparative examples 5 and 6 were tested for load bearing capacity according to ASTM D2783.

Conditions: rotation speed: 1760 ± 40 rpm

Duration: 10 seconds

Temperature: room temperature

Test parameters: ISL (Initial Seizure Load - initial setting load, units of measure - kgf) and WL (Weld Load - weld load, units of measure - kgf).

Test method: numerical values were determined by applying loads of 50 kgf, 63 kgf, 80 kgf, 100 kgf, 126 kgf, 160 kgf, 200 kgf, 250 kgf and 315 kgf up to WL

Evaluation of ISL was performed in accordance with the following criteria:

A load of 80 kgf or more has been recognized as ○ (tested).

A load of less than 80 kgf was recognized × (failed test).

In addition, WL was evaluated in accordance with the following criteria:

A load of 126 kgfs or more was recognized as ○ (tested).

A load of less than 126 kgf was recognized × (failed test).

Abrasion resistance test: tests on a four-ball friction machine ChShMT Shell

The test equipment and test methods were such that a load of 40 kgf was applied according to ASTM D4172, the oil temperature was 75 ° C, the tester was rotated at 1200 rpm for 1 hour, and the diameter of the abrasion mark at the point of contact was measured. Working tests 1 and 12 and comparative examples 5 and 6 were subjected to this test.

The evaluation of the test was carried out in accordance with the following criteria:

An abrasion mark diameter of 0.50 mm or less was recognized as ○ (tested).

An abrasion mark diameter of more than 0.50 mm was recognized × (failed the test).

Storage stability

The lubricating oil compositions of working examples 1-16 and comparative examples 1-12 were kept for 1 day (24 hours) at 25 ° C, after which the presence / absence of turbidity or sediment was visually determined.

Examples in which turbidity or precipitation did not appear were recognized as ○ (tested).

Examples in which turbidity or precipitation appeared are presented in the tables.

Regarding storage stability, examples in which turbidity or sediment appeared were not suitable as a lubricating oil composition for sliding guide surfaces, and therefore were not suitable for the other tests described above.

Test results

The test results for the working examples and comparative examples are presented in tables 1-3.

Table 3

Working
example 11 Working
example 12 Working
example 13 Working
example 14 Working
example 15 Working
example 16 Comparative
example 11 Comparative
example 12 Base oil 1 97.75 97.7 99 98.1 Base oil 2 97.7 Base oil 3 97.7 Base oil 4 62 Base oil 5 35.7 Base oil 6 19.54 Base oil 7 78.16 Additive 1-1 1,0 1,0 1,0 1,0 1,0 1,0 Additive 1-2 Additive 1-3 Supplement 3 0.6 Additive 2-1 Additive 2-2 Additive 2-3 0.25 0.25 0.25 0.25 0.25 0.25 0.25 Additive 2-4 Supplement 4 Additive 5 0.05 0.05 0.05 0.05 0.05 0.05 Additive 6 one one one one one one one one Coefficient
friction 0,092 0,094 0,092 0,093 0,092 0,092 0.143 0.122 Flash point (° C) 266 260 258 242 226 224 250 214 EP at ChWMT: ISL 160 EP at ChWMT: WL 200 Wear at ChShMT 0.40 Storage stability ○ ○ ○ ○ ○ ○ ○ ○

As shown in table 1, the composition from working example 1, containing base oil 1 and additives 1-1 and 2-3, had a low friction coefficient of 0.093 and a high flash point of 270 ° C and was found to be excellent as a lubricating oil composition for a guide surface slip. However, the composition of comparative example 1, which did not contain additive 2-3, passed in terms of flash point, but was found to be inappropriate due to the fact that it has a high coefficient of friction of 0.114.

Similarly, comparing working example 2 and comparative example 2, working example 2 turned out to be suitable, while comparative example 2, which differed from working example 2 by the absence of additives 2-3, was found to be inappropriate. In addition, working example 3, which was obtained by replacing the base oil 1 from working example 2 with base oil 2, turned out to be adequate.

In addition, compositions containing additive 1-2 but not containing additive 2, for example, in comparative examples 3 and 4, could not achieve good results.

Comparative example 5 differed from working example 1 in the absence of additive 1-1, but passed in terms of friction coefficient and flash point. However, comparative example 5 showed the same WL as in working example 1 at 126 kgf in the EP test for Shell Shell, but had a lower ISL (63 kgf) than in working example 1 (80 kgf) and had a worse diameter abrasion marks of 0.73 than in working example 1 (0.41) in a wear test at Shell Shell, and was found to be inappropriate.

Comparative example 6 contained the same components as working example 1, but contained less additives 1 and additives 2, and did not pass the friction coefficient, ISL and WL in the EP EP Shell test and the diameter of the abrasion mark in the wear test on BShMT Shell, and significantly inferior to working example 1.

Comparative example 7 contained the same components as working example 1, but contained a larger amount of additive 1 and additive 2, and also showed turbidity in the storage stability test and was unsuitable. Since turbidity formed, as mentioned above, other tests were not carried out.

As shown in table 2, all the compositions of working examples 4-8 contained base oil 1 and additive 1-1, all contained additive 5 and varied in type and content of additive 2, but all passed in terms of friction coefficient and flash point and were found to be suitable .

Working example 9 differed from working example 7 in that it contained additive 1-2 instead of additive 1-1, and working example 10 differed from working example 9 in that it contained base oil 2 instead of base oil 1, but working examples 9 and 10 passed in terms of the coefficient of friction and flash point and were found to be suitable.

Comparative example 8 differed from working examples 4-8 in that it contained 0.3% wt. additives 4 (behenic acid) instead of additives 2, and comparative example 9 differed from working examples 4-8 in that it contained 1.5% wt. additives 4 (behenic acid) instead of additives 2, but in comparative examples 8 and 9, a precipitation precipitated in the storage stability test, and therefore they turned out to be unsuitable. In addition, since precipitation occurred, other tests were not carried out.

Comparative Example 10 contained Additive 5 in base oil 1, but did not contain Additive 1 or Additive 2 and went through flash points but was found to be inappropriate due to the fact that it showed an extremely high coefficient of friction of 0.146.

As shown in table 3, working example 11 was obtained by adding additives 6 to the composition of working example 1 and went through the friction coefficient and flash point.

Working example 12 was obtained by adding additives 5 and additives 6 to the composition from working example 1 and went through the friction coefficient and flash point, and also showed the same abrasion mark diameter as in working example 1 in the Shell wear test, but demonstrated higher values for ISL and WL in the EP test for Shell FMCT, and therefore was found to be more preferred in cases where high EP properties are required.

Working examples 13-16 were obtained by replacing the base oil 1 used in working example 12 with other base oils and all went according to the friction coefficient, and working examples 15 and 16 were slightly worse in terms of flash point, but still passed.

Comparative example 11 differed from working example 11 in that it did not contain additive 1 or additive 2 and passed in terms of flash point, but was inappropriate due to the fact that it showed a high coefficient of friction, as in comparative example 10.

Comparative example 12 differed from working example 12 in that instead of additive 1-1 it contained additive 3, which is a phosphonic acid ester having a benzene ring, and did not pass in terms of friction coefficient and flash point, and was found to be inappropriate.

Claims (11)

1. The lubricating oil composition for the guide surface of the slide containing a base oil, wherein the base oil is a base oil belonging to group III and / or a base oil belonging to group IV in the API base oil categories, phosphonate represented by formula 1

(one), in which R ₁ denotes a saturated or unsaturated alkyl group having 12-22 carbon atoms, and R ₂ denotes a saturated or unsaturated alkyl group having 1-18 carbon atoms, and fatty acid represented by formula 2 R ₃ COOH (2), in which R ₃ denotes a saturated or unsaturated alkyl group having 7-17 carbon atoms, while phosphonate is contained in an amount of not less than 0.2% wt., but less than 2% wt. in relation to the total amount of the composition, and the fatty acid is contained in an amount of not less than 0.03% wt., but less than 1% wt. in relation to the total amount of the composition. 2. The lubricating oil composition for the sliding guide surface according to claim 1, which further comprises an antiwear additive and / or metal deactivator. 3. The use of a lubricating oil composition according to claim 1 or 2 for lubricating a sliding surface of a machine.