JPH0428792A - Refrigerating machine oil composition - Google Patents

Abstract

PURPOSE:To obtain the title thermally and chemically stable composition with extremely high lubricity by incorporating a base oil such as a mineral oil with a specified amount of a specific organic phosphate compound. CONSTITUTION:The objective composition can be obtained by incorporating (A) a base oil consisting of at least one kind of synthetic oil selected from mineral oils and/or synthetic hydrocarbon oils, polyether oils and ester oils with (B) (-)5.0 (pref. 0.1-1.0) wt.% of compound(s) of formula I and/or II[X<1>-X<3> are each R<1>O or R<2>O(AO)n (R<1> and R<2> are each 1-30C hydrocarbon; A is 28C alkylene;(n) is integer, 1-70)] and pref. furthermore, (C) <=5.0wt.% of a phosphoric ester of formula III (R<3> is 1-3C alkyl;(a) is integer, 0-2).

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a refrigerating machine oil composition that is thermally and chemically stable and has extremely good lubricity.

(Prior technology) Refrigerating machine oil is used in refrigeration compressors such as air conditioners, car air conditioners, and refrigerators, and is used to lubricate, seal, and seal the sliding parts of the refrigeration compressors.
It plays a role such as cooling.

In recent years, compressors have tended to have higher rotational speeds, higher performance, smaller size, and lighter weight. For this reason, refrigerating machine oils are increasingly required to have load resistance, wear resistance, and, as temperatures tend to rise, thermal stability.

On the other hand, with the recent movement to regulate fluorocarbons, the currently used R-12 (dichlorodifluoromethane), R-
As an alternative to 11 (trichlorofluoromethane),
Freon R-134a (1,1,
1,2-tetra7/L/oloethane L, R-152a
(1+' 1-difluoroethane) and Freon R-123 (1,1-dichloro2.2.2-
) refluoroethane) etc. have been proposed. Since these refrigerants do not contain or contain little chlorine in their molecules, the extreme pressure effect of the refrigerants themselves cannot be expected, and the refrigerating machine oils used in these refrigerants are required to have higher lubricity.

Various additives are used in general lubricating oils, but since refrigeration oil has the special characteristic of being used in a refrigerant atmosphere, additives for refrigeration oil are used to improve the oil's performance in such a refrigerant atmosphere. It must not impede stability and must have excellent low-temperature properties. However, many of the additives used in general lubricating oils, especially extreme pressure agents, have an adverse effect on stability in a refrigerant atmosphere, so there are a limited number of extreme pressure agents that can be applied to refrigerating machine oils.

Currently, only phosphoric acid esters such as triphenyl phosphate and tricresyl phosphate are mainly used as the extreme pressure side of mineral oil-based refrigerating machine oils.

(Problem B to be solved by the invention) However, phosphate ester-based extreme pressure agents such as triphenyl phosphate and tricresyl phosphate are R-11
Although it improves the lubricity of material sliding surfaces when using a refrigerant containing chlorine, such as R-12, it is not necessarily effective when using a refrigerant with a low chlorine content. In particular, in the case of refrigerants such as R-134a, which do not contain any chlorine, they do not contribute to the lubricity of the refrigerant at all, and therefore have a high resistance to refrigeration oil, which has extremely high wear resistance, especially refrigerants that do not contain chlorine. There is a need for a refrigeration oil with abrasive properties.

With the recent movement to regulate fluorocarbons, Freon R-1 has been introduced as a substitute for Freon R-12 (dichlorodifluoromethane), which is used as a refrigerant for car air conditioners and refrigerators.
34a (1,1,1,2-tetrafluoroethane)
However, this Freon R-134a has almost no compatibility with oil, and synthetic oils such as polyether oil and ester oil have been cited as useful candidates as refrigeration oil for Freon R-134a. There is. Compared to conventional mineral oil, synthetic oil has a thinner oil film even under the same pressure.
Moreover, since the other refrigerant (Freon R-134a) does not contain chlorine, the refrigerant itself cannot be expected to be effective in suppressing wear.

Therefore, the purpose of the present invention is to provide a refrigerant with low chlorine content or a refrigerant that does not contain chlorine by adding a wear resistance improver suitable for the refrigerating machine oil base material, which is mainly synthetic oil such as polyether or ester. The object of the present invention is to provide a refrigeration oil having good wear resistance and thermal stability even in a refrigeration compressor using a refrigerant.

(Means for Solving the Problem) As a result of intensive research into additives for improving the lubricity of synthetic refrigeration oil, the present inventors found that it has excellent low-temperature properties without impeding stability, and has excellent wear resistance. We have discovered a compound with extremely good properties, and have completed the present invention.

That is, the present invention provides a method for producing oil containing 1 selected from mineral oils, synthetic hydrocarbon oils, polyether oils, and ester oils.
The following general formula (1
) and/or general formula (2), X'-P-OH00,
(1) j X3- P (-OH), , ・, (2) (
In the general formula (IL (2), xl, X2 and x3 are each an oxygen-containing hydrocarbon group represented by the formula R'0 or the formula R20 (AO), and R' and R2 have 1 to 3 carbon atoms.
0 hydrocarbon group, A is an alkylene group having 2 to 8 carbon atoms, n
represents an integer from 1 to 70).
The present invention relates to a refrigerating machine oil composition characterized in that it contains not more than % by weight.

The refrigerating machine oil base oil according to the present invention has a pour point of 110°C or less, and has other low-temperature properties and thermal stability that are better suited for use as a refrigerating machine oil than mineral oils, synthetic hydrocarbon oils, polyether oils, and ester oils. The base oil is a mixture of one or more selected types. Here, the mineral oil is naphthenic mineral oil,
Examples of synthetic hydrocarbon oils include hard alkylbenzenes with branched alkyl groups, soft alkylbenzenes with linear alkyl groups, and paraffinic mineral oils.
Examples of polyether oils include alkyl ethers of polyoxypropylene, alkyl ethers of polyoxyethylene propylene glycol, and terminal esterified products thereof.
In addition, ester oils include monoester, diester,
Examples include polyol esters, complex esters, and oxyalkylene carbonates.

In the present invention, in the general formulas (1) and (2), the oxygen-containing hydrocarbon groups represented as R'O or R"0 (AO), -2 CaH,7O-1 GO-1CH3()0-1 C4H90(CzH40 valve 4, CsH+70(CJbOh., ■)0(CzH40) r.(C,H,0+-,. If the number of carbon atoms in the hydrocarbon groups R1 and R2 in the formula exceeds 30, it is not common or economical, and is preferably 1 to 18.Also, the number of carbon atoms in the oxyalkylene moiety A When n exceeds 8, it is similarly not common and uneconomical. Preferred are oxyethylene, oxypropylene, oxybutylene, or a mixture thereof.Furthermore, when n as the degree of polymerization is 7
When it exceeds 0, polyether-like properties become strong and the effect of improving lubricity decreases.

Specific examples of the compounds of general formulas (1)' and (2) include GAFAC-RE and RS manufactured by Toho Chemical Co., Ltd.
, RB series, product name JP manufactured by Johoku Kagaku ■
, commercially available as the LB series. Many of these commercially available products are mixtures of compounds represented by general formulas (1) and (2), and the ratio is not constant for each product.

In the present invention, the compounding amount of the compounds of general formulas (1) and (2) is 5% by weight or less. If this amount exceeds 5% by weight, there is a risk that the thermal stability of the oil will decrease and metals in the refrigeration system will corrode. The preferred amount is 0.1~
It is 1.0% by weight.

Further, in the present invention, compounds of general formulas (1) and (2) and the following general formula (3), (wherein R3 is an alkyl group having 1 to 3 carbon atoms, and a is 0 to 2
By using a phosphoric acid ester represented by (integer of ) in combination, a synergistic effect is exhibited and the lubricity is further improved. Examples of such phosphoric acid esters include triphenyl phosphate and tricresyl phosphate. If this amount exceeds 5% by weight, there is a concern that the thermal stability of the oil will decrease and metals in the refrigeration system will corrode.

The dramatic improvement in the lubricity of the present invention is due to the general formula (1), (2
) compounds form a strong chemically adsorbed film on the sliding surface, preventing metal-to-metal contact. Although the effect of combined use with phosphate ester is not clear, it is presumed that the sliding of the metal may compensate for the partially missing adsorption film.

In order to further improve the performance of the refrigerating machine oil composition of the present invention, if necessary, conventionally known refrigerating machine oil additives such as phenolics such as di-tert-butyl-P-cresol, phenyl-α-naphthylamine, N , N'-
Amine-based antioxidants such as di(2-naphthyl) p-phenylenediamine, silicone-based antifoaming agents, metal deactivators such as benzotriazole, hydrogen chloride scavengers such as glycidyl methacrylate, and phosphite esters. It is also possible to blend these agents alone or in combination.

(Example) Next, the present invention will be specifically explained using examples.

1-4 9 1-4 The characteristics of a refrigerating machine oil composition to which a predetermined amount of the compound represented by the above general formula (1) was added were evaluated. The following compounds were used as the darkening compound, base oil, and other additive compounds.

Basic polyether (Uniloop MB-11: manufactured by NOF ■, viscosity at 40°C 56 cSt pour point -40
°C) ((CIH+'tO)!P OH)tricresyl phosphate (manufactured by Ohana Kagaku ■, abbreviated as TCP) Performance evaluation was performed using the Falex test (ASTM
D-2670), the thermal stability was tested by a thermal stability test using a shield tube. In addition, the flocculation points using various refrigerants were also investigated to determine whether additive precipitation occurs at low temperatures in the presence of refrigerant and oil.

The Farex test (ASTM D-2670) is a cylindrical rotating shaft (pin) with a diameter of approximately 6 mm that is sandwiched between two blocks from the left and right sides, a load is applied to this, and the initial oil temperature is At 40°C, 1 rotation speed 300rpII+, and a load of 300 Lbf, refrigerant gas was added to 70 ml during the test.
In this test, the abrasion mass of the rotary shaft and V-block was measured after 1 hour of operation. In order to see the difference in lubricity depending on the refrigerant, R-12 (CChFz) was used as the refrigerant.
, R-22 (CHCIFz), R-134a (CJz
F*) was used.

Thermal stability test refers to the length 2 called shield tube.
00 m, inner diameter 6m+, thickness 2m+ tempered glass tube,
This is a test in which 1g each of refrigerant and sample oil are sealed together with metal wires of steel, copper, and aluminum, heated in a constant temperature bath at 175°C, and the degree of coloration (ASTMcolor) of the contents is recorded at regular intervals to observe changes over time. .

In addition, the flock point is determined by adding the refrigerant and sample oil to the glass tube at 9=1.
This was then slowly cooled with a dry ice acetone solution at a rate of 1° C./min, and the temperature at which flocs formed was determined.

The results of these tests are shown in Table 1.

The following can be said from the results in Table 1. From comparative examples, as refrigerants, R-12 has two chlorine atoms in one molecule, R-22 has one chlorine atom, and R-1 has no chlorine atom.
A test was conducted using No. 34a, and it was found that as the number of chlorine in the refrigerant molecules decreased, the lubrication conditions became more severe and the amount of wear increased. Regarding thermal stability, the trend is the opposite; as the number of chlorine increases, stability worsens.

In the examples in which the compounds of the present invention were added, the lubricity was greatly improved, and wear was at almost no level. Furthermore, the flocculation points are all below -60°C, there is no precipitation of additives at low temperatures, and the thermal stability is on the rise. Moreover, as shown in Example 4, a synergistic effect is observed when TCP is used in combination, and the level of wear is completely eliminated.

The refrigerating machine oil to which a predetermined amount of the mixture of the compounds of the above general formulas (1) and (2) was added was evaluated in terms of lubricity, thermal stability, and flocking point in the same manner as the method described above. I did it. As a refrigerant,
R-134a, which has the strictest lubrication conditions, was used. The following compounds were used as the compounds.

Basic ester (Unistar H334R: manufactured by NOF ■, viscosity at 40°C 20cSt, pour point -40°
C) Hard alkylbenzene (Bansolve H: Mitsubishi Yuka ■
viscosity 40 cSt at 40°C, pour point -50
°C or less) (hereinafter abbreviated as Alpen) -(L(2)) A (Mu)A RO(C
HzCHzO) , IP (OR) z and (RO(CH
zC) lzO), 1) z P OH 1::1
, n is 10 on average, and R is a methylphenyl group.

This is a mixture containing compounds having the same molecular formula as A in a ratio of 1:1, but n is 5 on average, and R is an octyl group.

Life triphenyl phosphate (manufactured by Daihe Kagaku Co., Ltd., TPPa
) The evaluation results are shown in Table 2.

From Table 2, the compounds represented by general formulas (1) and (2) improve the lubricity and also exhibit a synergistic effect with the additive of general formula (3), without deteriorating the properties of the refrigeration oil base material. , it was confirmed that the wear resistance was improved.

(Effects of the invention) As explained above, the refrigerating machine oil composition of the present invention has
Using mineral oil or synthetic oil as a base oil, the above general formula (1), (
By containing the compound shown in 2) at 0.5% by weight or less, the wear resistance is improved and the effect of suppressing metal wear is extremely large, and the thermal stability and low-temperature properties of the refrigerating machine oil base oil itself are improved. It has no adverse effect on.

Therefore, due to current regulations on fluorocarbons, there is a very high possibility that an alternative refrigerant for fluorocarbon R-12, which is a refrigerant for refrigerators, will be a refrigerant that does not contain chlorine in its molecules, such as fluorocarbon R134a. Compatible new synthetic refrigerating machine oil compositions include general formulas (1) and (2
The performance of the refrigerating machine oil composition of the present invention containing the compound shown in ) is excellent, and can be expected to meet various performance requirements from a practical standpoint.

Claims (1)

[Claims] 1. Using one or more synthetic oils selected from mineral oil and/or synthetic hydrocarbon oil, polyether oil, and ester oil as a base oil, the following general formula (1) is used. and/or general formula (2), ▲mathematical formula, chemical formula, table, etc.▼・
...(1) ▲There are mathematical formulas, chemical formulas, tables, etc.▼...(2) (In general formulas (1) and (2), X^1, X^2, and X^
3 is each individually represented by the formula R^1O or the formula R^2O(AO)_
An oxygen-containing hydrocarbon group represented by n, R^1, R_2
is a hydrocarbon group having 1 to 30 carbon atoms, A is an alkylene group having 2 to 8 carbon atoms, and n is an integer of 1 to 70). Refrigerating machine oil composition. 2. In the refrigerating machine oil composition, there are general formulas (3), ▲mathematical formulas, chemical formulas, tables, etc.▼...(3) (In the formula, R^3 is an alkyl group having 1 to 3 carbon atoms, and a is 0~
(representing an integer of 2) is 5.0
The refrigerating machine oil composition according to claim 1, which contains not more than % by weight.