JPS62158795A - Alkylbenzene-containing lubricant for flon compressor - Google Patents

Abstract

PURPOSE:To provide the titled lubricant having a low viscosity and capable of inhibiting sludge formation, which comprises a particular base oil having a decreased low-boiling fraction content. CONSTITUTION:A flon compressor lubricant comprising an alkylbenzene or a mixed oil of an alkylbenzene and a mineral oil as a base oil, wherein the content of fractions having a boiling point of 330 deg.C (under 1atm) or less of the lubricant is limited to 5vol% or less. The alkylbenzene which can be suitably employed may either have a branched side chain (hard type) or a straight side chain (soft type). A mineral oil of the paraffin group type may be employed. It is preferred that the mixing ratio of alkylbenzene to mineral oil be in the range of about 10:0- about 20:80vol%. When the alkylbenzene is present in an amt. of 20vol% or more, the compatibility with flon and fluidity at low temp. of the lubricant are improved. By the use of the above-mentioned lubricant, a low-viscosity lubrication is ensured, and the sludge formation and adherence around the discharge valve of the compressor can be inhibited.

Description

[Detailed Description of the Invention] The great invention of car weight is - CFC was created by @hkanei.L+: Lubricating oil used in compressors (so-called refrigeration oil), more specifically, a specific light distillate. The present invention relates to a lubricating oil for fluorocarbon compressors, which uses a mixed oil of flukylbenzene or alkylbenzene and mineral oil as the base oil, and has as much of the carbon content as possible removed.

Sumire and Tamama alkylbenzene has good fluorocarbon stability and low-temperature fluidity, so many technologies have been proposed for lubricating oils for fluorocarbon compressors using it as a base oil (for example,
JP-A-52-54707, JP-A-52-127904
No. 139608/1983). It is also known that alkylbenzenes can be used not only alone, but also in combination with mineral oil, and in particular, in combination with paraffin group or mixed group mineral oil.

By the way, lubricating oil for fluorocarbon compressors, for example, in hermetic compressors, is operated for a long period of time from several years to more than 10 years without oil change, so during this long period of use, sticky sludge or sticky sludge builds up on the discharge valve part of the compressor. A problem arises in that a coke-like substance (hereinafter simply referred to as sludge) is generated and adhered, resulting in a reduction in the refrigerating capacity.

Conventionally, as a measure to prevent the above-mentioned sludge generation,
-441) No. 9 is a lubricating oil for fluorocarbon compressors with a SUS viscosity in the range of 100 to 500 at 37.8°C (equivalent to approximately 20 = 100 cSt), and is 80% by volume in naphthene base oil.
A refrigerating machine oil is disclosed in which the above paraffin-based components are mixed with a paraffin-based mineral oil that distills at a temperature of 426.6° C. (converted to normal pressure) or higher.

That is, the above-mentioned known technology is based on the technical idea of expanding the narrow distillation range, which is a characteristic of naphthene-based mineral oil, by mixing paraffin-based mineral oil.

However, naphthene-based mineral oil is difficult to obtain stably in Japan, so there are restrictions on its use and it is not practical.In addition, as mentioned above, even when mixed with paraffin-based mineral oil, the viscosity decreases. However, in recent years, from the standpoint of energy saving, there has been an increasing demand for low-viscosity lubricating oils for fluorocarbon compressors, such as JIS VG 15-22.
An even lower viscosity (8 to 12 cSt) is desired.

C) The present inventor has studied the prevention of the above-mentioned sludge formation that occurs when using lubricating oil for Freon compressors, focusing on the fact that it is related to the viscosity of the lubricating oil. The present invention was developed based on the finding that reducing the content of low-boiling fractions among the components constituting lubricating oil is effective in preventing sludge formation.

Therefore, an object of the present invention is to provide a lubricating oil for a Freon compressor that has a low viscosity and can suppress the formation of the above-mentioned sludge.

In addition, in a lubricating oil for a Freon compressor based on alkylbenzene or a mixed oil of alkylbenzene and mineral oil, the proportion of components that boil at a temperature of 330°C (normal pressure equivalent) or lower in the lubricating oil is 5 volumes. % or less.

Can you understand the voice? The alkylbenzene used as the base oil in the present invention is
It may be a hard type having branches in the side chain or a straight chain soft type.

Originally, alkylbenzene is a by-product during the production of raw materials for soft or hard synthetic detergents, and consists of a mixture of mono-, di-, and trialkylbenzenes, and in those with side chains, the total number of carbon atoms in the alkyl group is about 12
~20 pieces.

As mentioned above, alkylbenzene, which is produced as a by-product as residual oil in the kettle during the production of synthetic detergents, consists of a mixture and has a boiling point of 330.
Since it contains light components whose temperature is lower than °C, the formation of the sludge is unavoidable when it is used as a lubricating oil for Freon compressors.

Therefore, in the present invention, the alkylbenzene mixture as described above is redistilled to remove as much of the light fraction with a boiling point of 330° C. or lower as possible, and the alkylbenzene base oil is used as the alkylbenzene base oil. When this is used alone as a lubricating oil, its viscosity is about 8~
A fraction with a temperature of about 50 cS t (40°C) is used.

In addition, in the case of using a mixed oil of alkylbenzene and mineral oil as a lubricating oil in the present invention, the mineral oil from which light fractions with a boiling point of 330°C or less are removed is mixed with the alkylbenzene to remove the light fractions with a boiling point of 330°C or less in the mixed oil. The fraction content should be 5% by volume or less, and the viscosity of the mixed oil should be about 8 to 5% by volume.
Adjust the mixing ratio to approximately 50 cS t (40°C). Note that mineral oil has a viscosity of 5 to 32 cSt (4
0° C.) is preferably used, and the mixing ratio of alkylbenzene and mineral oil is preferably about 100:0 to 20:80 ν/V%. Alkylbenzene in mixed oil is 20% by volume
If the above amount is present, the compatibility with fluorocarbons and the low-temperature fluidity of the lubricating oil for a fluorocarbon compressor using the same will be improved.

In particular, the mineral oils used here are paraffin-based or mixed-base mineral oils, and paraffin-based mineral oils include crude oil extracted from Minas crude oil and Chinese crude oil, and mixed-base crude oils include Arabian crude oil, Kraate crude oil, and Khafji crude oil. The remaining oils are distilled at atmospheric pressure, and the residual oil is distilled under reduced pressure to collect lubricating fractions for each boiling point range.Next, each fraction is extracted by solvent extraction (e.g. furfural extraction) or hydrogenated using a hydrogenation catalyst. Using a suitable combination of known purification methods such as dewaxing treatment, dewaxing treatment by solvent or hydrogenation, and adsorption treatment with clay, the product is purified to remove basic nitrogen compounds, sulfur compounds, unsaturated hydrocarbons, and waxes. Use what does not contain it as a lubricant.

Note that if these mineral oils are subjected to vacuum distillation to remove as much of the light fraction with a boiling point of 330°C or lower as possible, the viscosity will increase, so mixing with alkylbenzene can achieve the desired viscosity. In order to obtain oil, it is preferable to remove the high-temperature fraction along with the light fraction.

The lubricating oil for a fluorocarbon compressor according to the present invention uses the above-mentioned alkylbenzene or a mixed oil of the alkylbenzene and the above-mentioned mineral oil as a base oil, and the boiling point of the obtained lubricating oil is 3.
The content of light fractions below 30°C is 5% by volume or less, preferably 3% by volume or less, and by reducing the light fractions as much as possible in this way, the viscosity of the lubricating oil can be lowered. However, the generation of sludge at the discharge valve part of the compressor can be suppressed.

Incidentally, the viscosity of conventional fluorocarbon compressor lubricating oil is 15cS.
t (40℃), the boiling point range is usually about 300 to about 45
At 0°C, it contains about 5 to 15% by volume of light fractions below 330°C, and when the viscosity decreases to about 10 = 12 cSt, about 5 to 15 volumes of the light fractions are included. , the generation of the above-mentioned sludge is unavoidable.

When using the lubricating oil for fluorocarbon compressors according to the present invention, commonly used additives such as antifoaming agents,
A wear resistance improver and a hydrochloric acid scavenger may be blended as appropriate.

EXAMPLES The present invention and its effects will be specifically explained below with reference to Examples.

Example 1 This example shows the case where alkylbenzene alone was used as the base oil.

Lubricating oils are obtained by distilling commercially available fluorocarbon compressor lubricating oils using hard alkylbenzene as the base oil and reducing the fractions with boiling points below 330°C to various proportions as shown in Table 1 below.
Samples AB-2 to AB-4) were obtained. Table 1 shows the properties of each lubricating oil thus obtained and the commercially available lubricating oil mentioned above.

Example 2 This example shows the case where a mixed oil of alkylbenzene and mineral oil was used as the base oil.

The residual oil obtained by atmospheric distillation of Arabian Light crude oil as a mineral oil was distilled under reduced pressure to obtain a distillate oil (viscosity 8 cSt, 40°C).

This distillate was subjected to furfural extraction, catalytic hydrogenation using a catalyst, solvent dewaxing treatment, and clay treatment to obtain a refined mineral oil (sample MO-1) as shown in Table 2.
Sample MO-1) was redistilled to remove light fractions with a boiling point of 330°C or lower to obtain each mineral oil (sample MO-2, MO-3). Furthermore, a high boiling point fraction was partially removed from the mineral oil (MO-3) to obtain a mineral oil (MO-4). These MO-1 to MO-4
The properties of each mineral oil are shown in Table 2.

Next, each mineral oil MO-1 to MO-4 obtained as described above
was mixed with samples AB-1 to AB-4 of the alkylbenzene lubricating oils shown in Example 1 as shown in Table 3 to obtain lubricating oils.

Performance test of lubricating oil: Using the lubricating oil obtained as described above and the lubricating oil shown in Example 1, each was charged into a refrigerator compressor using Freon (R-12) as a refrigerant and operated for 1000 hours. After that, the amount of sludge adhering to the discharge valve was measured. In addition, the temperature of the discharge valve part during operation is 1) 0 to 1
The temperature was 20°C. The results are summarized in Table 3.

As seen in Table 3, sample numbers (3) and (4
), (8), (9), α0 and aυ all have a sludge amount of 15 (1) g or less, and have a higher effect of suppressing sludge generation than those containing more than 5 vol 1% of the above light fraction. It is recognized that

Claims (3)

[Claims] (1) In a lubricating oil for fluorocarbon compressors that uses alkylbenzene or a mixture of alkylbenzene and mineral oil as a base oil, the proportion of components that boil at a temperature of 330°C (normal pressure equivalent) or lower is 5% by volume or less. A lubricating oil for fluorocarbon compressors that is limited to: (2) Claim No. 1 which limits the proportion of components that boil at temperatures below 330°C (converted to normal pressure) to below 3% by volume.
) Lubricating oils listed in section ). (3) Mixed oil has a ratio of alkylbenzene and mineral oil of 100
:0 to 20:80V/V% (
Lubricating oil described in section 1).