JPH06192670A - Rotary pump oil - Google Patents

Abstract

PURPOSE:To provide a rotary pump oil excellent in especially low-temperature properties and to provide a rotary pump oil excellent also in oxidation stability. CONSTITUTION:The oil is prepared by using an alkyl-diphenyl as the base oil and optionally adding further a hindered phenol and a thioether.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary pump oil, and more particularly to a rotary pump oil which is excellent in low temperature characteristics and oxidation stability.

[0002]

2. Description of the Related Art There are various vacuum pumps such as a mechanical pump and a steam injection type pump, but a rotary pump is used to obtain a low vacuum state. In this pump, a rotor is provided in an eccentric state inside a cylinder having an intake port and an exhaust port, and the rotor rotates or oscillates. For example, with a bellows attached to the rotor, the space form in the cylinder is changed with time. Change with. The space is filled with oil, and the oil dissolves the gas inhaled from the intake port or discharges the dissolved gas and escapes the gas from the exhaust port as the space form changes. , This is repeated to create a vacuum state.

This oil, that is, a rotary pump oil, has a function of dissolving a low gas as described above, a sealing function of a cylinder and a rotor, a lubricating function of a sliding portion,
It must exert a cooling effect that suppresses heat generation due to high-speed rotation.

As such a rotary pump oil, a vapor pressure lower than that of a normal lubricating oil is required from the viewpoint of back diffusion of oil vapor, and a mineral oil or a synthetic oil type has been conventionally used. Examples of the latter include alkyl diphenyl ethers (for example, Japanese Examined Patent Publication Nos. 51-44263 and 52-
No. 24628), aromatic esters (trimellitic acid esters), alkyl naphthalenes, and fluoro oils are typical and have been put into practical use.

[0005]

However, the known rotary pump oil as described above is used as a direct coupling type rotary pump (a rotor is directly coupled to a motor) under a considerably low temperature condition (eg, -20 ° C.) in a cold region. Used),
The following problems occur.

That is, in the mineral oil type rotary pump oil, it is solidified and the pump cannot be used. Even with synthetic oil, the viscosity thereof increases, the torque increases, and the motor may be seized. Therefore,
What is excellent in low temperature characteristics is desired.

Further, since the rotary pump oil is used for a direct-coupled rotary pump, it rotates at a high speed, the oil temperature rises during operation, and the oil is easily oxidized. As the oxidation progresses, a resinous substance is deposited, and the vapor pressure rises due to the decomposition product, making it unusable. Therefore, it is desired that not only the low temperature characteristics are excellent, but also the heat resistance and the oxidation resistance are high.

The present invention solves the above problems, and an object of the present invention is to provide a rotary pump oil having excellent viscosity characteristics especially at low temperatures.

Another object of the present invention is to provide a rotary pump oil which is excellent in oxidation stability.

[0010]

SUMMARY OF THE INVENTION The present invention is a rotary pump oil containing alkyldiphenyl as a base oil.

Such a rotary pump oil has a low viscosity at a low temperature and an excellent low temperature characteristic.

Furthermore, the present invention is a rotary pump oil comprising an alkyldiphenyl base oil and a hindered phenol and / or thioether as an additive. Hindered phenols scavenge radicals, while thioethers exert a peroxide decomposing effect. The two act synergistically, and they are colored by heating like amine-based antioxidants and hydrolyzed by mixing water like phosphorus-based antioxidants to form strongly acidic substances. Therefore, the rotary pump oil of the present invention containing both of the above additives exhibits particularly excellent oxidative stability.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Representative examples of the alkyldiphenyl usable in the present invention are represented by the following general formula.

[0014]

[Chemical 1]

[R is an alkyl group having 10 to 20 carbon atoms,
m is 1 to 3 and n is 0 to 3 (when R is plural, they may be the same or different)] Specifically, n-decyldiphenyl, n-undecyldiphenyl, n-dodecyldiphenyl, n -Tridecyldiphenyl, n-tetradecyldiphenyl, n-heptadecyldiphenyl, n-hexadecyldiphenyl, n-nonadecyldiphenyl, n-octadecyldiphenyl, n-eicosyldiphenyl, 2
-Decyldiphenyl, 2-hexadecyldiphenyl, 2
-Octadecyldiphenyl, 3-decyldiphenyl, 4
-Decyldiphenyl, di (n-decyl) diphenyl, di (n-dodecyl) diphenyl, di (2-decyl) diphenyl, di (2-dodecyl) diphenyl, penta (2-tetradecyl) diphenyl, tri (2-dodecyl) The (2
-Tetradecyl) diphenyl, hexa (2-dodecyl)
Examples thereof include diphenyl and the like. R is preferably an alkyl group having 12 to 18 carbon atoms, m is 1 and n is 0 to 1, and particularly preferred is R is an alkyl group having 12 to 14 carbon atoms and m is 1 ,
n is 1, or R is an alkyl group having 16 to 18 carbon atoms, m is 1 and n is 0. If the alkyl group having less than 10 carbon atoms has poor lubricity, if it has more than 20 carbon atoms,
The viscosity becomes high, and the thermal stability and oxidative stability become poor.

The kinematic viscosity at 100 ° C. is 2.0 to
Those having a thickness of 30.0 mm ² / s can be used.

Even if it is out of the above range,
From the viewpoint of average molecular weight, any compound can be used as long as it falls within the above range by mixing.

Next, the additives used in the present invention will be described. First, as a typical example of a hindered phenol, that is, a phenol having a sterically hindering group, one having a 2-t-butylphenol structure or a 2,6-di-t-butylphenol structure.

For example,

[0020]

[Chemical 2]

[R 'is C ₁₈ H ₃₇ ]

[0022]

[Chemical 3]

[K is 2 to 6] The following can also be used.

[0024]

[Chemical 4]

Particularly preferred is n-octadecyl-3- (4-hydroxy-3 ', 5'-di- with the following structure:
t-butylphenyl) propionate,

[0026]

[Chemical 5]

Hexamethylene glycol bis [p- (3,5-di-tbutyl-4-hydroxyphenyl) propionate] having the following structure.

[0028]

[Chemical 6]

Typical examples of the thioether used in the present invention are represented by the following general formula.

S (CH ₂ CH ₂ COOR ₁ ) ₂ [R
₁ may be the same or different, and is an alkyl group having 10 to 20 carbon atoms] or C (CH ₂ OC (O) CH ₂
CH ₂ SR ₂ ) ₄ [R ₂ may be the same or different,
It is also an alkyl group having 10 to 20 carbon atoms].

Specifically, the following are preferable.

Dilauryl thiodiisopropionate S
(CH ₂ CH ₂ COOC ₁₂ H ₂₅ ), ditridecylthiodipropionate S (CH ₂ CH ₂ COOC ₁₃ H ₂₇ ),
Dimyristyl thiodipropionate S (CH ₂ CH ₂
COOC ₁₄ H ₂₉ ), lauryl stearyl thiodipropionate H ₂₅ C ₁₂ O (O) CCH ₂ CH ₂ S (CH ₂ C
H ₂ COOC ₁₈ H ₃₇ ), distearyl thiodipropionate S (CH ₂ CH ₂ COOC ₁₈ H ₃₇ ), pentaerythritol tetra (β-laurylthiopropionate) C (CH ₂ OC (O) CH ₂ CH ₂ S ₁₂ C
H ₂₅ ) ₄ .

The above additives may be used alone, but if a hindered phenol type and a thioether type are used in combination, a very high antioxidant performance is obtained by a synergistic effect. When compounding the additives, the amount of hindered phenol added is usually 0.05 to 0.5 of the total rotary pump oil.
10% by weight, preferably 0.1-5% by weight. It is particularly preferably 0.1 to 2.0% by weight. Thioether is
0.05-10% by weight of the total rotary pump oil, preferably 0.1-5% by weight. Particularly preferably 0.1
It is 2.0% by weight.

The rotary pump oil of the present invention contains
In addition to the above additives, any additive that improves its performance can be used. Examples include corrosion inhibitors,
Examples thereof include antiwear agents, metal deactivators, rust preventives, antifoaming agents and the like.

[0035]

INDUSTRIAL APPLICABILITY The rotary pump oil of the present invention containing alkyldiphenyl as a base oil has a lower pour point than known rotary pump oils and has a low temperature (for example, −20), as evidenced by the following examples. The viscosity at (° C.) is suitable for operating a rotary pump. As described above, according to the present invention, it is possible to provide a rotary pump oil which has excellent low-temperature characteristics and is particularly suitable for use in a low-temperature environment such as a cold region. Furthermore, the low vapor pressure and the degree of water separation required for rotary pump oil are not inferior to those known.

Further, the alkyl diphenyl base oil to which an additive of a hindered phenol and a thioether is added is particularly excellent in oxidation stability, has improved durability, and can be used even under severe conditions of use.

[0037]

Example Preparation of rotary pump oil Example 1 Diphenyl (462 g) (3 mol) was placed in a four-necked flask having an internal volume of 2 liters equipped with a stirrer, a thermometer, a dropping funnel, and a reflux condenser under a nitrogen atmosphere. It heated and stirred at 70 degreeC and it was set as the solution. Then, 4.2 g of anhydrous aluminum chloride
(0.03 mol) was added and dissolved. After that, increase the temperature to 8
Raise to 0 ° C and α-olefin (dodecene) 504g
(3 mol) was added dropwise over 30 minutes and stirred. After the dropping was completed, the temperature in the reaction system was raised to 100 ° C. and stirring was continued for 3 hours.

After allowing to cool, 1 liter of 10% Na ₂ CO ₃ aqueous solution was added, and the mixture was stirred, transferred to a separating funnel, and the lower water tank was removed. Further, the oil layer was washed twice with 1 liter of water, and then the oil layer was distilled under reduced pressure to fractionally distill unreacted materials and products. The main fraction 198-235 ° C / 3Torr didodecyldiphenyl (370 g) was obtained.

Example 2 Ditetradecyldiphenyl (240 to 250 ° C.) was used in the same manner as in Example 1 except that 584 g (3 mol) of tetradecene was used instead of 504 g (3 mol) of dodecene.
/ 4 Torr) 420 g was obtained.

Example 3 Dodecene 504 used in Example 1
450 g of monohexadecyldiphenyl (254 to 260 ° C./4 Torr) was obtained in the same manner except that 672 g (3 mol) of hexadecene was used instead of g (3 mol).

Example 4 In the same manner as in Example 1, except that 504 g (1.5 mol) of octadecene was used instead of 504 g (3 mol) of dodecene, monooctadecyldiphenyl (268 to
270 ° C./5 Torr) was obtained.

Example 5 To 990 g of didodecyldiphenyl obtained in Example 1, as a hindered phenol, 3,5-di-t-butyl-4-hydroxyphenylpropionic acid octadecyl ester (trade name: ADEKA STAB AO- 50, manufactured by Asahi Denka Kogyo Co., Ltd.), 5 g,

[0043]

[Chemical 7]

As a thioether, S- (CH ₂ CH ₂ C
5 g of OOC ₁₃ H ₂₇ ) ₂ ditridecyl thiodipropionate (trade name: ADEKA STAB AO-503A, manufactured by Asahi Denka Kogyo Co., Ltd.) was added and stirred at 60 ° C. to obtain 1000 g of the blended oil of Example 5.

The mass and composition of each of the oils 1 to 4 in the above example were analyzed by mass spectrometry (DX-303 manufactured by JEOL Ltd.) (FD method).
And GPC analysis (LC-6A manufactured by Shimadzu Corporation).

Results of use as rotary pump oil The oils of Examples 1 to 5 were directly combined with a rotary pump (available from Co., Ltd.).
When actually used with Shimadzu GDH-361) (temperature: -20 ° C.), the motor was rotated at the same time when the switch was turned on, and the vacuum degree was 10 ⁻³ Torr measured by a MacLeod vacuum gauge. In this way, at low temperature, the pump does not work,
No seizure occurred and the pump operated smoothly.

[0047] relates to a rotary pump oil of the Performance Test invention of Examples 1-5, their density (JIS K 2249), flash point (the 2265
), Pour point (2269), viscosity (2283), viscosity index, low temperature viscosity (JPI (The Japan Petroleum Institute) -5S-26-85.ASTM D)
2983-80), total acid number (JIS K 2501), water separation (same as 2520)
, 54 ° C., oil layer (cc) -water layer (cc) -emulsion layer (cc) (time (minutes) on the left) and oxidation stability (2514).
The results are shown in Table 1 below.

Similar characteristics were investigated for the following publicly known rotary pump oils.

Comparative Example 1 Mineral oil, trade name: Neovac M
R100 (manufactured by Matsumura Oil Research Institute) 2 mineral oil, trade name: Neovac MR200, (same as above) 3 alkyl diphenyl ether, trade name: Neovac SOM (same as above) 4 alkyldiphenyl ether, trade name: Neobac SOH (same as above) 5 alkylnaphthalene + Ethylene propylene copolymer, trade name: Arvoyl R-7000 (manufactured by Nippon Vacuum Technology Co., Ltd.) 6 Component of Comparative Example 1 + antioxidant (same component and amount as in Example 5) 7 Monoalkyl diphenyl ether (number of carbon atoms 18 alkyl groups) These results are also shown in Table 1.

[0050]

[Table 1]

Symbols in Table Cn-: Indicates that the number of alkyl carbons is n. MDP: Monoalkyldiphenyl DDP: Dialkyldiphenyl As can be seen from the above table, each Example according to the present invention has a pour point Low, low temperature viscosity, excellent low temperature characteristics. Also, the degree of water separation is good. On the other hand, the comparative examples are inferior in one or more of high pour point, high low temperature viscosity, low oxidative stability, and water separation.

Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display area C10M 129: 14 129: 76) C10N 30:02 30:04 30:10 40:06 40:30 40:34

Claims (1)

[Claims] 1. A rotary pump oil containing alkyldiphenyl as a base oil.