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Refrigeration lubricant composition

a technology of refrigerant and composition, which is applied in the direction of lubricant composition, domestic cooling apparatus, lighting and heating apparatus, etc., can solve the problems of poor refrigeration, reduced amount of circulating refrigerant in the refrigerating cycle, and part of the refrigeration lubricant ejected from the compressor may stagnate in the low temperature region, etc., to achieve excellent low-temperature stability, not easy to crystallize, and high viscosity

Inactive Publication Date: 2005-07-07
NOF CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0007] It is an object of the present invention to provide a refrigeration lubricant composition that does not easily crystallize at low temperatures, in other words, a refrigeration lubricant composition that has excellent low-temperature stability. It is another object of the present invention to provide a refrigeration lubricant composition having high viscosity, excellent compatibility with chlorine-free hydrofluorocarbon refrigerants, and excellent long-term stability in a low temperature region of the refrigerating machine.
[0021] The refrigeration lubricant composition of the present invention does not cause precipitation of crystals over a long period of time in the low temperature region, and thus it has excellent low-temperature stability. Moreover, it also has good lubricity, stability under coexistence with a chlorine-free hydrofluorocarbon refrigerant (evaluated by sealed tube test), and compatibility with chlorine-free hydrofluorocarbon refrigerants, which are required for refrigeration lubricant compositions. Therefore, the refrigeration lubricant composition of the present invention is useful for a lubricant for refrigerating machines that employ a chlorine-free hydrofluorocarbon refrigerant or as a refrigerant working fluid in which it is mixed with a chlorine-free hydrofluorocarbon refrigerant.

Problems solved by technology

On the other hand, however, a part of the refrigeration lubricant ejected from the compressor may stagnate in the low temperature region.
In particular, if the lubricant stagnates in the low temperature region for a long period of time, then it is crystallized and the amount of the circulating refrigerant in the refrigerating cycle is reduced, which may lead to problems such as poor refrigeration.
However, the mixed esters obtained from a combination of a polyhydric alcohol and a specific carboxylic acid as described in the patent publications noted above have not been sufficiently examined for their ability of maintaining low-temperature stability over a long period of time.
Thus, it is not possible to prevent crystallization from occurring in the low temperature region, and thus these esters lack long-term stability.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

example 1

Preparation of Ester

[0068] First, the mixed alcohol and the mixed carboxylic acid shown in Table 1 were placed in a one-liter four-necked flask provided with a thermometer, a nitrogen inlet tube, a stirrer and a cooling tube such that the ratio of the hydroxyl group in the mixed alcohol and the carboxyl group in the mixed carboxylic acid is 1:1.1 in the equivalent ratio, and then reacted under a nitrogen at 220° C. at an atmospheric pressure while water generated by the reaction was removed by distillation. During the reaction, the hydroxyl value of the reaction mixture was monitored, and the reaction was stopped at the point when the hydroxyl value became lower than 2.0 mgKOH / g. Then, stripping was performed under a reduced pressure of 1 to 5 kPa to remove unreacted carboxylic acid for one hour. The resultant reaction mixture was washed with an aqueous solution of potassium hydroxide. Washing was repeated five times so that the pH of the discharged water became neutral. Then, the ...

examples 2 to 6

[0069] Esters (i.e., esters B to F) were obtained in the same manner as in Example 1 except that the mixed alcohols and the mixed carboxylic acids shown in Table 1 were used. The kinematic viscosity at 40° C. and 100° C. and the viscosity index of each ester were measured according to the above-described method. Table 1 also shows the results.

example 7

Preparation of Base Stock of Lubricant

[0071] The above-described ester A was used as a base stock of a lubricant (this base stock is referred to as base stock 1). The kinematic viscosity at 40° C. and 100° C., viscosity index, acid value, hydroxyl value, color number, volume resistivity, pour point, two-phase separation temperature, and Falex test pin friction amount of the obtained base stock 1 were measured according to the above-described methods. Furthermore, the long-term low-temperature test and the sealed tube test were performed. Table 2 shows the results.

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Abstract

A refrigeration lubricant composition comprises an ester obtained from a mixed alcohol and a mixed carboxylic acid as a main component. The mixed alcohol comprises 65 to 99.95 mol % of pentaerythritol and 0.05 to 35 mol % of dipentaerythritol, the mixed carboxylic acid comprises 25 to 55 mol % of monocarboxylic acid having 5 to 8 carbon atoms and 45 to 75 mol % of isononanoic acid, and the composition has a hydroxyl value of 5.0 mgKOH / g or less and an acid value of 0.05 mgKOH / g or less.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a refrigeration lubricant composition. More specifically, the present invention relates to a refrigeration lubricant composition that is used for a chlorine-free hydrofluorocarbon refrigerant, wherein the composition comprises a polyol ester as the main component and has excellent low-temperature stability, lubricity, stability under coexistence with a chlorine-free hydrofluorocarbon refrigerant, and has excellent compatibility with chlorine-free hydrofluorocarbon refrigerants. The present invention also relates to a refrigerant working fluid containing the refrigeration lubricant composition and a refrigerating apparatus including the refrigerant working fluid. [0003] 2. Description of the Related Art [0004] Conventionally, refrigerants containing chlorofluorocarbon have been used for air conditioning equipment such as room air conditioners and packaged air conditioners, low tempera...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C10M105/42C09K5/04C10M171/00
CPCC09K5/045C10M171/008C10M2207/2835C10N2220/027C10N2220/028C10N2240/30C10N2230/02C10N2230/06C10N2230/10C10N2230/12C10N2220/302C10N2030/02C10N2030/06C10N2030/10C10N2030/12C10N2040/30C10N2020/069C10N2020/071C10N2020/101C10M105/42
Inventor YAMADA, MUNEHIROSHIZUKA, NOBUHIKOMEMITA, MICHIMASAMIYASHITA, HIROKO
Owner NOF CORP
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