KR970003957B1 - Lubricating oil for refrigerators using r-134a cooling agent - Google Patents

Abstract

Pentaerysritol is reacted with mono-aliphatic acid of C5-C9 in catalyst and solvent, and then catalyst, solvent and un-reacted monoaliphatic acid are eliminated to obtain a refrigerant oil(R-134a) that is added to alkybenzotriazol. Accordingly, the refrigerant oil improves the attrition irrelevant to influence of thermal and oxidation stability.

Description

Friction Relieving Agent for Refrigerator Oil for Household Refrigerator Using R-134a as Refrigerant

The present invention relates to a friction relieving agent for refrigerator oil for home refrigerators using a new alternative refrigerant R-134a (1,1,1,2-tetrafluoroethane) as a refrigerant.

R-12 Freon refrigerant, which has been used as a conventional refrigerant, is regulated due to the ozone depletion, and R-134a has been developed as a new refrigerant. However, since R-134a has a greater polarity than conventional R-12 refrigerants, R-134a has a problem in that it does not dissolve in natne-based mineral oil or alkylbenzene-based synthetic oil, which has been used as a conventional refrigerator oil. Therefore, the developed countries such as the United States, Japan and the United Kingdom are spurring the development of a new structure of refrigeration oil compatible with R-134a, and several types of refrigeration oil have been reported.

The structure of the refrigeration oil for R-134a that has been reported is polyhydric alcohols such as neopentyl glycol, trimethylolpropane, pentaerythritol, dipentaerythritol having 1 to 6 hydroxykeys, and imitation fatty acid having 2 to 9 carbon atoms and 2 to C carbon atoms. It is known that a compound having a kinematic viscosity of 1 to 100 cSt at 100 ° C. among ester compounds synthesized from 10 divalent fatty acids is used as a refrigerator oil.

However, the ester compounds of all the structures synthesized with polyhydric alcohols and fatty acids were measured to have a wear diameter of 0.800 to 1.000 mm as a result of measuring their wear performance with a 4-ball tester. There are problems such as deepening wear.

Conventionally, in order to solve this problem, friction relieving agents including phosphorus such as trecresyl phosphate and dialkyldithioin acid zinc salt have been added. However, since these compounds have very poor thermal and oxidative stability, oil of There is a problem such as accelerated deterioration to shorten the life. Therefore, there is a strong demand for the development of new additives which greatly increase the performance of wear and at the same time do not affect the thermal and oxidative stability.

In the present invention, in order to solve such a problem, by using an alkylated benzotriazole which is used as a metal inactivator as an additive, a novel additive which significantly increases the wear performance of the refrigeration oil and at the same time does not affect heat and oxidation stability has been found. .

When the present invention is described in detail, 5 to 6 moles of C5 to 9 mono fatty acids having 5 to 9 carbon atoms are reacted with 1 mole of pentaerythritol in the presence of a catalyst and a solvent, the catalyst is washed with water, and the solvent and unreacted monofatty acid are distilled off. Refrigerator oil having a kinematic viscosity of 15 ° C. to 35 cSt is obtained.

The tricresyl phosphate, which has been used as a conventional friction modifier, was kneaded with varying amounts of 0.02 ~ 2% in each of the refrigeration oils thus synthesized, and the wear diameter of the four balls was measured for 21 days at 175 ° C. During the sealed tube test (sealed tube test) was carried out to measure the change in color and the value of the computer. On the other hand, in the case of the alkaline benzotriazole used as an additive in the present invention was kneaded while changing up to 0.02 ~ 2% to perform abrasion performance and oxidation stability test in the same manner to compare the performance with the conventional additives. Experimental results show that the additive according to the present invention greatly increases the wear performance and does not affect the oxidation stability at all.

The details of the present invention will be described in detail with reference to Examples.

Example 1

4 liter kettle reactor equipped with a stirrer, reflux cooler, Dean Stark apparatus, thermometer, etc. Mole) and reacted at 250 ° C. for 15 hours, and unreacted 2-ethylhexyl acid and 2-methhexyl acid were distilled off under reduced pressure to obtain a reaction product. The physical properties of the obtained reaction product are shown in Table 1.

[Table 1] Physical properties of the reaction product of Example 1

* ANTI / ASHRAE 97 ~ 1983, based on the Sealed Glass Tube Method, which is an experimental result after 21 days of 175 ° C, and measured according to ASTM-color ASTM D 1500-82.

Examples 2-8

Tricresyl phosphate used as a conventional friction modifier in the reaction product synthesized in Example 1 was kneaded while varying the amount added up to 0.02 to 2% to measure the four-hole wear diameter for each content and at the same time the shield glass tube method ( As a result of the test by the Sealed Glass Tube Method, changes in the acid value and ASTM-color were measured and compared with those of Example 1. Table 2 shows the experimental results.

[Table 2] Physical Properties of Tricresyl Phosphate

* ANTI / ASHRAE 97 ~ 1982, based on the Sealed Glass Tube Method, is a test result after 21 days of 175 ° C. ASTM-color: Measured according to ASTM D 1500-82.

Examples 9-15

In Example 1, the alkylated benzotriazole used as an additive in the present invention was kneaded while varying the amount added up to 0.02 to 2 to measure the four-hole wear diameter for each content, and at the same time, the sealed glass tube method. As a result, the change in the acid value and the ASTM color was measured and compared with the results of Example 1 and Examples 2-8. The measured test results are shown in Table 3.

TABLE 3 Physical Properties of Alkylated Benzotriazole

* ANTI / ASHRAE 97 ~ 1983, based on the Sealed Glass Tube Method, which is an experimental result after 21 days of 175 ° C, and is measured according to ASTM-Color: ASTM D 1500-82.

As shown in the above embodiment, the conventional friction modifier improves abrasion performance but promotes heat decomposition to shorten the life of the oil. However, the alkylated benzotriazole used as an additive in the present invention not only improves abrasion performance but also has excellent stability due to heat and oxidation, and thus has an excellent effect of preventing wear and oxidation of refrigerator oil for home refrigerators using R-134a as a refrigerant. .

Claims (1)

A friction reducing agent for refrigerator oil, comprising adding alkylated benzotriazole to refrigerator oil for domestic refrigerators using R-134a as a coolant.