JPH1030095A - Polyol ester-based lubricating oil - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high-performance polyol ester-based lubricating oil improved in compatibility with a substitute fluorocarbon in a range of 28-40cst dynamic viscosity at 40 deg.C, excellent in hydrolysis resistance and low in pour point. SOLUTION: This lubricating oil comprises a mixture of (A) a polyol ester composed of a 6-17C acid residue in which an α carbon of the acid residue is branched in a tertiary from and the whole >=4C alkyl groups bonded to the α carbon contain one or more branched chains and the alcohol residue of a neopentyl polyol and (B) a polyol ester composed of a 6-17C acid residue in which an αcarbon of the acid residue is branched in a secondary or tertiary form and the whole alkyl groups bonded to the α carbon are straight-chains and the alcohol residue of the neopentyl polyol and has 28-40cst dynamic viscosity at 40 deg.Ccst.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a polyol ester used for lubricating oils such as refrigerating machine oils, and more particularly, to a polyol ester having good compatibility with an alternative fluorocarbon, excellent hydrolysis resistance and low pour point.

[0002]

2. Description of the Related Art Chlorine-containing chlorofluorocarbons and hydrochlorofluorocarbons have been widely used as refrigerants used in refrigerators. However, in recent years, restrictions on the use of chlorofluorocarbons have become stricter worldwide since chlorine contained in chlorofluorocarbons destroys the ozone layer in the stratosphere. Therefore, chlorine-free hydrofluorocarbons have begun to be used as new refrigerants. On the other hand, the mineral oil-based and alkylbenzene-based refrigerating machine oils that have been used so far have poor compatibility with the above-mentioned new refrigerants, and are difficult to use. Therefore, a polyol ester-based refrigerating machine oil having good compatibility with a new refrigerant has been studied as an alternative refrigerating machine oil.

[0003] Conventional polyol esters are disclosed in
As described in JP-A No. 5484 and JP-A-5-70789, it is produced by subjecting a fatty acid and a polyhydric alcohol to an esterification reaction under heating. This reaction is 200
It is known that the reaction rate is low even when the reaction is carried out at a high temperature of not less than ℃, and in the case of industrial production, it is necessary to use a large capacity reactor.

In order to avoid such a reaction at a high temperature for a long time, JP-A-4-314793 and JP-A-5-314793 have been used.
271676 and JP-A-5-12991 disclose a method for producing a polyol ester via an acid chloride. However, the method via acid chloride requires acid chlorides such as phosphorus trichloride, phosphorus pentachloride, and thionyl chloride to produce acid chloride from fatty acids, and the handling is complicated and the production process becomes complicated. .

When a polyol ester is used as a refrigerating machine oil for a CFC substitute, a kinematic viscosity at 40.degree.
For a refrigerator having a rotary compressor of 3.5 to 16.5 cst (VG15), a polyol ester of VG32 is used. VG for air conditioners
32, VG56, VG68 grade polyol esters are used. Of these viscosity grades, VG1
The polyol ester 5 can be used as a refrigerator oil by mixing a polyol ester obtained from 2-ethylhexanoic acid and neopentyl glycol and a polyol ester obtained from 2-ethylhexanoic acid and pentaerythritol.

On the other hand, a VG having a kinematic viscosity at 40 ° C. of 28.8-35.2 cst, which is used for refrigerators and air conditioners.
For example, Japanese Patent Application Laid-Open No. 5-209
No. 171 discloses a mixed ester of a polyol ester obtained from 3,5,5-trimethylhexanoic acid and neopentyl glycol and a polyol ester obtained from 3,5,5-trimethylhexanoic acid and trimethylolpropane (mixing weight ratio 35 / 65), 2-methylhexanoic acid / 2
-Polyol ester obtained from ethylhexanoic acid (60/40 weight ratio) mixed acid and pentaerythritol, 2
-Methylhexanoic acid / 3,5-dimethylhexanoic acid (8
0/20 weight ratio) and a polyol ester obtained from pentaerythritol, a polyol ester obtained from 3,5-dimethylhexanoic acid and trimethylolpropane, and the like. Although these polyol esters have an excellent pour point of −40 ° C. or lower, 1,1,1,2-tetrafluoroethane (R-134a), which is a candidate for an alternative fluorocarbon, and a polyol ester in a weight ratio of 9/1.
The mixture on the low side often has a high two-phase separation temperature,
Further, all of the above esters cannot be said to have satisfactory hydrolysis resistance, and it is difficult to use them as refrigeration oil for rotary type refrigerators and air conditioners.

As described above, the polyol ester of VG15 is produced by mixing a polyol ester obtained from 2-ethylhexanoic acid and neopentyl glycol and a polyol ester obtained from 2-ethylhexanoic acid and pentaerythritol. The VG32 polyol ester can be obtained by changing the mixing ratio. However, the pour point becomes too high by changing the mixing ratio, so that it cannot be used as refrigerating machine oil.

Further, difluoromethane (R-32) and pentafluoroethane (R-
125) and the like, and R-407C
(The mixing weight ratio of R-32 / R-125 / R-134a is 23/25/52) and R-410A (R-32 / R-1
A mixed refrigerant having a mixing weight ratio of 25/50) is listed as a promising candidate. These alternative CFCs are R-134
In general, the range of compatibility with polyol ester tends to be narrower than that of a alone, and this is particularly remarkable on the low temperature side. JP-A-5-17789 discloses that R-22 is used as an alternative refrigerant to R-22.
Evaluation of esters has been made using -32 and R-125. Esters that are well compatible with R-32 and R-125 have been proposed, but those having a kinematic viscosity lower than VG32,
Some of them have poor hydrolysis resistance and are difficult to use as refrigerator oil for rotary type refrigerators and air conditioners.
As described above, since the polyol ester of VG32 is used not only for refrigerators but also for air conditioners, R-407C, R-4
Although it is necessary to be compatible with a wide range of new refrigerants such as 10A, polyol esters obtained from existing fatty acids and polyhydric alcohols can satisfy only compatibility, but have other basic properties such as hydrolysis resistance and pour point. There is no one that satisfies everything.

[0009]

The inventor pays particular attention to high-viscosity grades, and has a high compatibility with good compatibility with CFC substitute, excellent hydrolysis resistance, high volume resistivity and low pour point. And applied for a patent (Japanese Patent Application Nos. 7-320233 and 7-320234).
No., Japanese Patent Application No. 7-320236, Japanese Patent Application No. 8-39998
issue). In the conventional method for producing a polyol ester, when a fatty acid and a polyhydric alcohol are reacted as described above,
Even at a high temperature of 200 ° C. or higher, the reaction rate is extremely slow, and the acid chloride is used in the method involving acid chloride, so that the handling and production process are complicated.
As for the polyol ester of VG32, several kinds of polyol esters have been proposed so far by a combination of a fatty acid and a polyhydric alcohol, but R-407C and R-41 have been proposed.
VG32 (Kinematic viscosity at 40 ° C of 28 to 40 cst) has not been obtained, which satisfies all the required basic characteristics such as compatibility with a new refrigerant such as 0A, hydrolysis resistance, and pour point (−40 ° C. or less). The development of a high-performance polyol ester in (1) is strongly desired. The object of the present invention is to solve the above-mentioned problems of the conventional polyol ester for lubricating oil, and to use a hydrofluorocarbon which is a strong alternative fluorocarbon, especially R-407C, and a refrigerant which is hardly compatible with the polyol ester such as R-410A. An object of the present invention is to provide a high-performance polyol ester having good compatibility, excellent hydrolysis resistance, a low pour point, and a kinematic viscosity at 40 ° C of 28 to 40 cst.

[0010]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies on polyol esters for lubricating oils having the above-mentioned problems, and found that isooctene, carbon monoxide and neopentyl polyol were reacted in the presence of hydrogen fluoride. The resulting polyol ester is mixed with a polyol ester obtained by reacting 1-octene and carbon monoxide with neopentyl polyol in the presence of hydrogen fluoride to obtain a polyol ester having a kinematic viscosity at 40 ° C of 28. ~ 40 cst
The present invention was found to have good compatibility with the alternative CFC, excellent hydrolysis resistance, and low pour point.

That is, according to the present invention, A) the α-carbon of the acid residue is tertiary-branched, and the alkyl group having 4 or more carbon atoms connected to the α-carbon has 6 to 6 carbon atoms each having at least one branch. 1
An acid residue of 7 and a polyol ester composed of an alcohol residue of neopentyl polyol; and B) an α-carbon of the acid residue is branched into secondary or tertiary, and an alkyl group connected to the α-carbon is It is a mixture of an acid residue having 6 to 17 carbon atoms, which is all linear, and a polyol ester composed of an alcohol residue of neopentyl polyol.
Is a polyol ester-based lubricating oil characterized by having a kinematic viscosity in the range of 28 to 40 cst.

[0012]

DETAILED DESCRIPTION OF THE INVENTION The polyol ester mixture of the present invention is prepared by reacting isooctene or 1-octene with carbon monoxide and neopentyl polyol in hydrogen fluoride, and the polyol ester derived from isooctene and 1-octene is produced. The acid residue has 6 to 17 carbon atoms. Neopentyl glycol is suitably used as the neopentyl polyol constituting the polyol ester mixture of the present invention. Isooctene or 1- in hydrogen fluoride
By reacting the fatty acid fluoride obtained by reacting octene and carbon monoxide with neopentyl polyol, a polyol ester of a fatty acid having a branched alkyl group of A) and neopentyl polyol in the case of isooctene is obtained, When it is derived from 1-octene, a polyol ester having a linear alkyl group of B) is obtained.

The isooctene used for producing the polyol ester of the present invention is 2,4,4-trimethyl-1-
In addition to pentene and 2,4,4-trimethyl-2-pentene, 2,4,4-trimethyl-1-pentene and 2,4
A commercial product, which is an approximately 7: 3 mixture of 4-trimethyl-2-pentene, can also be used. By using isooctene as a raw material, the reaction of dimerizing isooctene and the reaction of breaking the alkyl chain of isooctene occur simultaneously before the reaction of isooctene and carbon monoxide, and a fatty acid fluoride having various carbon numbers is obtained. Is branched into tertiary, and when the alkyl group connected to the α carbon has 4 or more carbon atoms, all of the alkyl groups are 1
Have more than one branch. By using isooctene as a raw material in this way, the fatty acid residue becomes highly branched, so that the compatibility range between the ester obtained therefrom and the alternative fluorocarbons, particularly the compatibility range on the low temperature side, is wide. Become. Also, by using isooctene as a raw material, a fatty acid fluoride having various carbon numbers reacts with neopentyl polyol, so that the number of carbon atoms and the degree of branching of two acid residues in one polyol ester molecule are different. The amount of polyol ester becomes very large (hybrid ester), which also greatly contributes to expanding the compatibility range with the alternative CFC. Furthermore, by using isooctene as a raw material, almost all of the α-carbon of the acid residue is branched into tertiary, so that the produced polyol ester is extremely hard to undergo hydrolysis. The pour point of the polyol ester derived from isooctene can be further lowered by performing purification such as hydrogenation treatment and high-boiling cut distillation, but it is difficult to reduce the pour point to -40 ° C or lower.

In the polyol ester derived from 1-octene, by using 1-octene as a raw material, 1-octene itself is isomerized before 1-octene reacts with carbon monoxide, or 1-octene is dimerized. Since various fatty acid fluorides can be obtained by the occurrence of such reactions, the number of polyol esters differing in the number of carbon atoms and the degree of branching of the two acid residues in one polyol ester molecule increases in the same manner as in isooctene. The compatibility range becomes wider. Further, by using 1-octene as a raw material, the α-carbon of the acid residue is branched into secondary or tertiary, so that the produced polyol ester is extremely hard to undergo hydrolysis. The pour point of the polyol ester derived from 1-octene is further lowered since the degree of branching of the acid residue is lower than that of the polyol ester derived from isooctene. Therefore, the pour point can be easily lowered by mixing the polyol ester derived from 1-octene with the polyol ester derived from isooctene.

On the other hand, since the acid residue of isooctene-derived polyol ester is more highly branched than that of 1-octene-derived polyol ester, the isooctene-derived polyol ester has a wider compatibility range with the alternative fluorocarbon. Become. Isooctene-derived polyol ester and 1-
The mixing ratio of the octene-derived polyol ester is not limited, but preferably the isooctene-derived polyol ester is 70 to 85% by weight, and the 1-octene-derived polyol ester is 15 to 30% by weight. By mixing the polyol ester derived from 1-octene with the polyol ester derived from isooctene in the range of 15 to 30% by weight, the pour point can be lowered without substantially changing the compatibility range with the alternative chlorofluorocarbon.

Neopentyl glycol is suitably used as the neopentyl polyol constituting the polyol ester mixture of the present invention. The polyol ester lubricating oil of the present invention is a composition of the polyol ester mixture represented by the following chemical formula: It is preferred that A)
The polyol ester mixture represented by the general formula (I):

Embedded image The polyol ester satisfying 5 ≦ m ≦ 8 and 5 ≦ n ≦ 8 is 52.0 to 58.0% by weight, 5 ≦ m ≦ 8 and 8 <n
The polyol ester satisfying ≦ 16 is 38.0 to 44.0.
By weight, the polyol ester having 8 <m ≦ 16 and 8 <n ≦ 16 is 3.0 to 7.0% by weight (m and n are integers).

The polyol ester mixture derived from isooctene (A) has an increased proportion and a decreased proportion decreases the kinematic viscosity. As a result, the amount of the 1-octene-derived polyol ester is less than 15% by weight. And it becomes difficult to improve the pour point. When the ratio decreases and the ratio increases, the kinematic viscosity increases, and in order to set the kinematic viscosity at 40 ° C. in the range of 28 to 40 cst, the addition amount of the 1-octene-derived polyol ester is reduced from 30% by weight. , The range of compatibility with the alternative CFC gradually narrows.

The polyol ester mixture of B) is represented by the general formula (II):

Embedded image 93.0-97.0% by weight of a polyol ester satisfying 5 ≦ p ≦ 8 and 5 ≦ q ≦ 8, 5 ≦ p ≦ 8 and 8 <q
The polyol ester of ≦ 16 is 3.0 to 5.0% by weight, and the polyol ester of 8 <p ≦ 16 and 8 <q ≦ 16 is 0.1 to 4.0% by weight.

The proportion of the 1-octene-derived polyol ester in B) increases, and the decrease in the proportion decreases the kinematic viscosity. As a result, the addition amount of the 1-octene-derived polyol ester is 30% by weight. Therefore, the compatibility range with the alternative CFC gradually narrows. When the ratio decreases and the ratio increases, the kinematic viscosity gradually increases, and the kinematic viscosity at 40 ° C. increases from 28 to 40 cst.
In this case, the amount of the polyol ester derived from 1-octene is less than 15% by weight, and it is difficult to improve the pour point.

The method for producing the polyol ester of the present invention includes: 1) a method of reacting isopentene or 1-octene with carbon monoxide in hydrogen fluoride and then reacting neopentyl polyol; A method in which isooctene or 1-octene is supplied and reacted in the presence of carbon monoxide and neopentyl polyol, and 3) isooctene or 1-octene and neopentyl polyol in the presence of hydrogen fluoride and carbon monoxide. A method of simultaneously supplying and reacting can be performed. According to the method 1) among these methods, the highest polyol ester yield can be obtained.

When producing a polyol ester derived from isooctene, the amount of hydrogen fluoride to be used is 2 times or more and less than 5 times the mole of isooctene used. If the molar ratio is less than 2 times, the rate of the carbonylation reaction decreases and the amount of side reactions increases, which is not economically advantageous. Further, even if the molar ratio is 5 times or more, the carbonylation reaction rate does not change, and the heat load at the time of recovering hydrogen fluoride by distillation increases, which is not advantageous.

In the present invention, the reaction temperature between isooctene and carbon monoxide is -50 to -10 ° C, preferably -4.
0 to -20 ° C. If the reaction temperature is too low, not only is the reaction rate reduced, but also the kinematic viscosity becomes too high, and the energy required for cooling becomes large, which is not economical. On the other hand, when the reaction temperature is -10 ° C or higher, the kinematic viscosity is lower than the desired kinematic viscosity.

When producing a polyol ester derived from 1-octene, the amount of hydrogen fluoride used is 5 times or more and 30 times or less, preferably 7 times or more and 15 times or less with respect to 1-octene used. It is. If the molar ratio is less than 5 times, the carbonylation reaction rate decreases and the amount of side reactions increases, so that it is not economically advantageous. If the molar ratio is more than 15 times, the carbonylation reaction rate does not change, the capacity of the reactor increases, and the heat load when recovering hydrogen fluoride by distillation increases, which is not economical.

The reaction temperature between 1-octene and carbon monoxide is-
It is 30-50 degreeC, Preferably it is -20-40 degreeC. If the reaction temperature is too low, the reaction rate decreases, and the energy required for cooling increases, which is not economical. On the other hand, when the reaction temperature is 20 ° C. or higher, the amount of side reactions increases and the kinematic viscosity gradually increases.

Isooctene or 1- in hydrogen fluoride
Reaction pressure between octene and carbon monoxide is 10-100kg
/ Cm ² G or less, preferably 10 to 80 kg / c
m ² G. When the reaction pressure is low, the yield of the intermediate acid fluoride decreases. However, the pressure is 100kg /
Even if it is higher than cm ² G, the yield hardly changes and the equipment cost increases, so that it is not industrially advantageous. The reaction pressure is a case where high-purity carbon monoxide is used.If the carbon monoxide gas to be used contains a considerable amount of inert gas, the partial pressure of carbon monoxide is equal to the reaction pressure. It is determined to be. The amount of carbon monoxide used in the reaction is determined by the reaction pressure.

The amount of neopentyl polyol used in the esterification reaction is 1.0 to 1.1 times the molar number of carbon monoxide absorbed in the carbonylation reaction when producing a polyol ester derived from isooctene. (Based on the number of moles of OH groups in neopentyl polyol). If the amount of neopentyl polyol used is too small, unreacted acid fluoride will remain. If the used amount of neopentyl polyol is too large, a large amount of monoester is produced. When producing a polyol ester derived from 1-octene, the amount of neopentyl polyol used in the esterification reaction is 0.9 to 1.1 with respect to the number of moles of carbon monoxide absorbed in the carbonylation reaction.
It is preferable to set the molar ratio (based on the number of moles of the OH group of neopentyl polyol), preferably 0.95 to 1.05. If the amount of neopentyl polyol used is too small, the amount of unreacted acid fluoride recovered will increase. If the used amount of neopentyl polyol is too large, a large amount of monoester is produced.

The reaction temperature of the esterification is -50 to 10
C, preferably -30 to 10 C, and the reaction is carried out under pressure or normal pressure. The esterification reaction of the present invention can be carried out in a batch system or a continuous system, but the continuous system is advantageous for industrial use. The conventional method for producing an ester while removing water produced from a fatty acid and a polyhydric alcohol can be basically carried out only in a batch system, and furthermore, several kinds of fatty acids having different degrees of branching of α-carbon are reacted with the polyhydric alcohol. In this case, the esterification may not be carried out well because the reaction rate varies depending on the degree of branching of the fatty acid, and the ester production method of the present invention is also advantageous in these respects.

When hydrogen fluoride and a polyol ester are industrially separated after the esterification reaction, a method of recovering hydrogen fluoride by distillation under reflux of a saturated hydrocarbon is employed. The hydrogen fluoride recovered by distillation is recycled to the carbonylation reactor. As the saturated hydrocarbon, hexane, heptane, octane, nonane, decane and the like are used. The saturated hydrocarbon serves to supply heat of decomposition of hydrogen fluoride and the polyol ester and dilute the polyol ester at the bottom of the column.

The polyol ester obtained by the esterification reaction is subjected to a hydrolysis treatment carried out by adding water in order to further improve the distillation purification or hydrolysis resistance, which is usually carried out, after the recovery and distillation of hydrogen fluoride. , A clay treatment, and the like. It is also effective to carry out high-boiling cut distillation, hydrogenation treatment and the like as necessary to improve the pour point, volume resistivity, color value and the like.

The polyol ester-based lubricating oil of the present invention may optionally contain additives such as antioxidants, antiwear agents and epoxy compounds which have been used as additives for conventional refrigerator oils. it can. The kinematic viscosity of the polyol ester derived from isooctene at 40 ° C. can be in the range of 60 to 80 cst by combining the above reaction conditions. Similarly, the 1-octene-derived polyol ester can have a kinematic viscosity at 40 ° C. in the range of 8 to 15 cst by combining the above reaction conditions.

The polyol ester-based lubricating oil of the present invention is used as a lubricating base oil for CFC substitutes. Not only 1,1,1,2-tetrafluoroethane (R-134a), which is the most common substitute for CFCs, Difluoromethane / pentafluoroethane /
The weight ratio of 1,1,1,2-tetrafluoroethane is 15
30 to 15/30 to 50/70 (R-4
07C) and a composition (R) in which the weight ratio of difluoromethane / pentafluoroethane is 40-50 / 50-60.
-410A). For this reason, the two-phase separation temperature with the alternative CFC, the shield tube test for measuring the hydrolysis resistance and the pour point are defined, and the mixing ratio of the polyol ester derived from isooctene and the polyol ester derived from 1-octene is set to the preferred range described above. if you did this,
The physical properties of the polyol ester-based lubricating oil of the present invention are as follows. The pour point is measured by a method according to JIS K-2269, and the pour point of the polyol ester-based lubricating oil of the present invention is -40 ° C or less.
Using iron, copper, and aluminum as catalysts,
A sample and a refrigerant (alternative Freon) prepared to 000 ppm or less and an acid value of 0.01 mg KOH / g or less are sealed, and
It is a method of measuring the acid value after heating at 28 ℃ for 28 days,
In the polyol ester-based lubricating oil of the present invention, the refrigerant is 1,
The acid value when 1,1,2-tetrafluoroethane (R-134a) is used is 0.02 mgKOH / g or less.

The two-phase separation temperature is determined by mixing the polyol ester and the refrigerant (alternative CFC) with the refrigerant / polyol ester in a weight ratio of 9%.
/ 1 is a temperature at which the polyol ester and the refrigerant are separated when the mixture is melted at room temperature and gradually cooled or heated, and the polyol ester system usually has a two-phase separation temperature on the low temperature side and the high temperature side. In the polyol ester-based lubricating oil of the present invention, a) 1,1,1,2-tetrafluoroethane (R-134a) is used as a refrigerant, and R-134a / polyol ester-based lubricating oil is mixed at a weight ratio of 9/1. The two-phase separation temperature at the time of cooling is -60 ° C or less on the low temperature side and 100 ° C or more on the high temperature side, and b) difluoromethane / pentafluoroethane / 1,1,1,2-tetrafluoroethane is contained in the refrigerant by weight. 23/25/52 freon mixture (R-407C)
When the R-407C / polyol ester-based lubricating oil is mixed at a weight ratio of 9/1, the two-phase separation temperature is −45 ° C. or less on the low temperature side and 80 ° C. or more on the high temperature side, and c) Difluoromethane / pentafluoroethane in a weight ratio of 5
Using a 0/50 mixture (R-410A), R-410
When the A / polyol ester-based lubricating oil is mixed at a weight ratio of 9/1, the two-phase separation temperature is −30 ° C. or less on the low temperature side and 60 ° C. or more on the high temperature side.

[0033]

Next, the present invention will be described in detail with reference to examples. However, the present invention is not limited by these examples. The hydrolysis resistance test and the compatibility test of the esters obtained in the respective Examples and Comparative Examples were performed as follows. The pour point was measured according to JISK-2269. (Hydrolysis resistance test) In a glass test tube, iron,
Copper and aluminum wires each 8 cm, 10 g of ester sample adjusted to 1000 ppm water, refrigerant (R-134a) 2
g, and sealed, and the sealed glass tube is heated at 200 ° C. for 28 days to measure the acid value. (Compatibility test) 0.2 g of the sample ester and each refrigerant (R-
134a, R-407C, R-410A) in a glass tube and sealed. Cooling or heating was performed at a rate of 1 ° C./min from 20 ° C., and the two-phase separation temperatures on the low temperature side and the high temperature side were measured.

Example 1 Isooctene-derived esters were produced using a stainless steel autoclave equipped with a Nack drive type stirrer, three inlet nozzles at the top, and one outlet nozzle at the bottom, and the inside temperature of which could be controlled by a jacket. went. First, after replacing the inside of the autoclave with carbon monoxide, 100 mol (2000 g) of hydrogen fluoride was introduced, cooled to -30 ° C, and pressurized to 20 kg / cm ² with carbon monoxide. While supplying carbon monoxide so as to maintain the reaction temperature at -30 ° C and the reaction pressure at 20 kg / cm ² , the isooctene mixture (2,4,4-trimethyl-1-pentene and 2,4,4
-7: 3 mixture of trimethyl-2-pentene) 31.
3 mol (3506 g) was supplied from the gas phase part of the autoclave to synthesize an acid fluoride mixture. After the completion of the supply of the isooctene mixture, the stirring was continued for about 20 minutes until the absorption of carbon monoxide disappeared. The amount of carbon monoxide absorbed is 2
It was 8.8 mol. Set the temperature in the autoclave to -10
C., and the pressure was reduced to normal pressure. Then, an equimolar amount (based on the number of moles of OH groups of neopentyl glycol) of neopentyl glycol was supplied to the autoclave and reacted for 2 hours. Was. The reaction solution was supplied to a hydrogen fluoride recovery distillation column to recover hydrogen fluoride from the top and crude polyol ester from the bottom. Crude ester recovered from the bottom is rectified in a rectification column,
5% by weight of water was added to the obtained ester, and the mixture was stirred at 200 ° C. for 3 hours to perform a hydrolysis treatment. After treatment with the adsorbent, the mixture was hydrogenated with 5% Ru / C and dehydrated with nitrogen bubbling to obtain a purified polyol ester. The acid value of the obtained polyol ester was 0.01 mgKOH / g, and the water content was 90 ppm. The kinematic viscosity at 40 ° C. was measured using an Ubbelohde viscometer and was found to be 80 cst.

Next, an ester derived from 1-octene was produced using the autoclave used for producing an ester derived from isooctene. After replacing the inside of the autoclave with carbon monoxide, 100 mol of hydrogen fluoride (2000
g), cooled to a temperature of −15 ° C., and
Pressurized to kg / cm ² . While supplying carbon monoxide so as to maintain the reaction temperature at -15 ° C. and the reaction pressure at 20 kg / cm ² , 8.3 mol (933 g) of 1-octene was supplied from the gas phase of the autoclave, and acid was supplied. A fluoride mixture was synthesized. After the end of 1-octene supply, stirring was continued for about 20 minutes until absorption of carbon monoxide was no longer observed.
The amount of carbon monoxide absorbed was 6.5 mol. After the temperature in the autoclave was lowered to −10 ° C. and the pressure was reduced to normal pressure, an equimolar amount (based on the number of moles of neopentyl glycol OH group) of neopentyl glycol was absorbed into the autoclave. The mixture was supplied and reacted for 2 hours. The reaction solution was supplied to a hydrogen fluoride recovery distillation column to recover hydrogen fluoride from the top and crude polyol ester from the bottom. The crude ester recovered from the bottom of the column was subjected to a low-boiling component cut in a rectification column, and then 5% by weight of water was added to the obtained ester, followed by stirring at 200 ° C. for 3 hours for hydrolysis treatment. Was done. 5% Ru after treatment with adsorbent
/ C and subjected to dehydration with nitrogen bubbling to obtain a purified polyol ester. The acid value of the obtained polyol ester is 0.01 mgKOH / g, and the water content is 90 ppm.
Met. When the kinematic viscosity at 40 ° C. was measured using an Ubbelohde viscometer, it was 11 cst.

The compositions of the polyol ester derived from isooctene and the polyol ester derived from 1-octene were as follows. Isooctene-derived polyol ester 5 ≦ m ≦ 8 and 5 ≦ n ≦ 8 polyol ester 52.3% by weight 5 ≦ m ≦ 8 and 8 <n ≦ 16 polyol ester 41.4% by weight 8 <m ≦ 16 6.3% by weight of a polyol ester satisfying 8 <n ≦ 16 1-Polyester derived from octene 5 ≦ p ≦ 8 and a polyol ester satisfying 5 ≦ q ≦ 8 95.2% by weight 5 ≦ p ≦ 8 and 8 < 4.0% by weight of polyol ester satisfying q ≦ 16 0.8% by weight of polyol ester satisfying 8 <p ≦ 16 and 8 <q ≦ 16 0.8% by weight of the polyol ester derived from isooctene / 1 the polyol ester derived from 1-octene. As a result, a polyol ester having a kinematic viscosity at 40 ° C. of 33 cst was obtained.

Example 2 The same procedure as in Example 1 was repeated except that the feed amount of isooctene was 29.4 mol and the carbonylation temperature of 1-octene was -10 ° C.
-Synthesis of octene-derived polyol ester. The resulting polyol ester has an acid value of 0.01
mgKOH / g, water content was 90 ppm. When the kinematic viscosity at 40 ° C. was measured using an Ubbelohde viscometer, they were 74 cst and 12 cst, respectively.

The compositions of the polyol ester derived from isooctene and the polyol ester derived from 1-octene were as follows. Polyester derived from isooctene 5 ≦ m ≦ 8 and 5 ≦ n ≦ 8 54.2% by weight Polyol ester satisfying 5 ≦ m ≦ 8 and 8 <n ≦ 16 40.6% by weight 8 <m ≦ 16 5.2% by weight of polyol ester satisfying 8 <n ≦ 16 1-Polyester ester derived from octene 5 ≦ p ≦ 8 and 94.5% by weight of polyol ester satisfying 5 ≦ q ≦ 8 5 ≦ p ≦ 8 and 8 < Polyol ester satisfying q ≦ 16 4.3% by weight Polyol ester satisfying 8 <p ≦ 16 and 8 <q ≦ 16 1.2% by weight The polyol ratio derived from isooctene / 1-octene is 85 by weight. As a result, a polyol ester having a kinematic viscosity at 40 ° C. of 40 cst was obtained.

Example 3 A polyol ester derived from isooctene and a polyol ester derived from 1-octene were synthesized in the same manner as in Example 1 except that the supply amount of isooctene was changed to 26.3 mol. The resulting polyol ester has an acid value of 0.1 each.
01 mgKOH / g and water content was 90 ppm. When the kinematic viscosity at 40 ° C. was measured using an Ubbelohde viscometer, they were 65 cst and 11 cst, respectively.

The compositions of the polyol ester derived from isooctene and the polyol ester derived from 1-octene were as follows. Isooctene-derived polyol ester 5 ≦ m ≦ 8 and 5 ≦ n ≦ 8 polyol ester 56.8% by weight 5 ≦ m ≦ 8 and 8 <n ≦ 16 polyol ester 39.4% by weight 8 <m ≦ 16 And a polyol ester satisfying 8 <n ≦ 16 3.8 wt% 1-octene-derived polyol ester 5 ≦ p ≦ 8 and a polyol ester satisfying 5 ≦ q ≦ 8 95.2 wt% 5 ≦ p ≦ 8 and 8 < 4.0% by weight of polyol ester satisfying q ≦ 16 8% by weight of polyol ester satisfying 8 <p ≦ 16 and 8 <q ≦ 16 The weight ratio of the polyol ester derived from isooctene / 1 to the polyol ester derived from 1-octene is 85. As a result, a polyol ester having a kinematic viscosity at 40 ° C. of 31 cst was obtained.

Example 4 A polyol ester derived from isooctene and a polyol ester derived from 1-octene were synthesized in the same manner as in Example 2 except that the supply amount of isooctene was changed to 25.0 mol. The resulting polyol ester has an acid value of 0.0
1 mgKOH / g and water content was 90 ppm. Also 4
When the kinematic viscosity at 0 ° C. was measured using an Ubbelohde viscometer, it was 56 cst and 12 cst, respectively.

The compositions of the polyol ester derived from isooctene and the polyol ester derived from 1-octene were as follows. Isooctene-derived polyol ester 5 ≦ m ≦ 8 and 5 ≦ n ≦ 8 polyol ester 60.5% by weight 5 ≦ m ≦ 8 and 8 <n ≦ 16 polyol ester 36.9% by weight 8 <m ≦ 16 2.6% by weight of polyol ester satisfying 8 <n ≦ 16 1-polyol ester derived from octene 5 ≦ p ≦ 8 and 94.5% by weight of polyol ester satisfying 5 ≦ q ≦ 8 5 ≦ p ≦ 8 and 8 < 4.3% by weight of polyol ester satisfying q ≦ 16 8% by weight of polyol ester satisfying 8 <p ≦ 16 and 8 <q ≦ 16 1.2% by weight of the polyol ester derived from isooctene / 1 the polyol ester derived from 1-octene As a result, a polyol ester having a kinematic viscosity at 40 ° C. of 31 cst was obtained.

Example 5 The procedure of Example 1 was repeated to synthesize a polyol ester derived from isooctene and a polyol ester derived from 1-octene, except that the supply amount of isooctene was 38.5 mol. The resulting polyol ester has an acid value of 0.0
1 mgKOH / g and water content was 90 ppm. Also 4
The kinematic viscosity at 0 ° C. was measured using an Ubbelohde viscometer, and was 100 cst and 11 cst, respectively.

The compositions of the polyol ester derived from isooctene and the polyol ester derived from 1-octene were as follows. Polyester derived from isooctene 5 ≦ m ≦ 8 and 5 ≦ n ≦ 8 47.2% by weight Polyol ester 5 ≦ m ≦ 8 and 8 <n ≦ 16 44.3% by weight 8 <m ≦ 16 8.5% by weight of a polyol ester satisfying 8 <n ≦ 16 1-Octene-derived polyol ester 5 ≦ p ≦ 8 and a polyol ester satisfying 5 ≦ q ≦ 8 95.2% by weight 5 ≦ p ≦ 8 and 8 < 4.0% by weight of polyol ester satisfying q ≦ 16 0.8% by weight of polyol ester satisfying 8 <p ≦ 16 and 8 <q ≦ 16 The weight ratio of the polyol ester derived from isooctene / 1 to the polyol ester derived from 1-octene is 62. As a result of mixing at / 38, a polyol ester having a kinematic viscosity at 40 ° C. of 31 cst was obtained.

Comparative Example 1 A polyol ester derived from isooctene was synthesized in the same manner as in Example 1 except that the supply amount of isooctene was 25.0 mol and the carbonylation reaction temperature was 0 ° C. The acid value of the obtained polyol ester was 0.01 mgKOH /
g and water content were 90 ppm. When the kinematic viscosity at 40 ° C. was measured using an Ubbelohde viscometer, it was 32 cst.
Met. The composition of the obtained polyol ester was as follows. 62.3% by weight of a polyol ester satisfying 5 ≦ m ≦ 8 and 5 ≦ n ≦ 8 23.6% by weight of a polyol ester satisfying 5 ≦ m ≦ 8 and 8 <n ≦ 16 8 <m ≦ 16 and 8 <n ≦ The polyol ester, which is 16, 1.1% by weight, and the other polyol ester, 13.0% by weight In addition, the polyol ester derived from 1-octene was not mixed.

Comparative Example 2 A 1-liter four-necked flask was equipped with a stirrer, a thermometer, a nitrogen blowing tube, and a dehydrating tube equipped with a condenser. 1.2 mol (161 g) of trimethylolpropane and 3,5-
3.6 mol (475 g) of dimethylhexanoic acid was placed in the flask and subjected to an esterification reaction at 240 ° C. for 10 hours under a nitrogen stream to obtain a triester. The obtained triester was dehydrated by nitrogen bubbling. The acid value of the polyol ester was 0.01 mgKOH / g, and the water content was 90 ppm. When the kinematic viscosity at 40 ° C. was measured using an Ubbelohde viscometer, it was 30 cst.

Comparative Example 3 2-Methylhexanoic acid and 2-ethylhexanoic acid were charged into the same flask as in Comparative Example 4 at a weight ratio of 60/40, and pentaerythritol was similarly charged with 2-methylhexanoic acid and 2-methylhexanoic acid. The esterification reaction was carried out in the same manner as in Comparative Example 4 by charging so as to be equimolar to the total mole of ethylhexanoic acid (based on the number of moles of the OH group of pentaerythritol). The obtained tetraester was dehydrated by nitrogen bubbling. The acid value of the polyol ester is 0.01 mg KOH /
g and water content were 90 ppm. The obtained tetraester was measured for kinematic viscosity at 40 ° C. using an Ubbelohde viscometer, and was found to be 33 cst.

Comparative Example 4 2-Methylhexanoic acid and 3,5-dimethylhexanoic acid were charged into the same flask as in Comparative Example 4 at a weight ratio of 80/20, and pentaerythritol was similarly charged with 2-methylhexanoic acid. Equimolar to total mole of 3,5-dimethylhexanoic acid (based on mole number of OH group of pentaerythritol)
And an esterification reaction was carried out in the same manner as in Comparative Example 4. The obtained tetraester was dehydrated by nitrogen bubbling. The acid value of the polyol ester is 0.01 m
gKOH / g and water content were 90 ppm. The kinematic viscosity of the obtained tetraester at 40 ° C. was measured using an Ubbelohde viscometer, and it was 30 cst.

Table 1 shows the results of hydrolysis resistance tests, pour points and kinematic viscosities of the esters obtained in each of the examples and comparative examples. R-134a, R-407C and R-410A
Table 2 shows the results of the compatibility test with. Comparative Example 2,
Compatibility test with R-407C and R-410A refrigerants with lower solubility than R-134a because the low-temperature two-phase separation temperature with R-134a did not reach -60 ° C or lower in 3 and 4. Has not gone.

[0050]

TABLE 1 Hydrolysis test (acid value mg KOH) pour point kinematic viscosity (40 ° C.) after pre-test test ° C. cst Example 1 0.01 0.01 -42.5 33 Example 2 0.01 0.01 -40.0 40 Example 3 0.01 0.01 -40.0 31 Example 4 0.01 0.01 -35.0 31 Example 5 0.01 0.05 -42.5 31 Comparative Example 1 0.01 0.01 -32.5 32 Comparative Example 2 0.01 2.82-55.0> 30 Comparative Example 3 0.01 0.93-55.0> 33 Comparative Example 4 0.01 2.93 −55.0> 30

[0051]

[Table 2] Compatibility test R-134a R-407C R-410A Separation temperature ° C Low side High side Low side High side Low side High side High side Example 1 -60> 100 <-50 80 <-38 60 <Example 2 −60> 100 <−54 80 <−42 60 <Example 3−60> 100 <−52 80 <−40 60 <Example 4 −60> 100 <−58 80 <−47 60 <Example 5 −60 > 100 <−38 80 <−26 60 <Comparative Example 1-60> 100 <−60> 80 <−50 60 <Comparative Example 2−40 100 <No Measurement Not Measured Not Measured Comparative Example 3 -40 100 <No measurement No measurement No measurement No measurement Comparative example 4 -48 100 <No measurement No measurement No measurement No measurement

[0052]

As is apparent from the above results, a polyol ester derived from isooctene and a polyol ester derived from 1-octene synthesized in the presence of hydrogen fluoride are mixed to have a kinematic viscosity at 40 ° C of 28 to 40 cst. The polyol ester-based lubricating oil of the present invention prepared in the range of
The new alternative fluorocarbons R-407C and R-410A, which are hardly compatible with conventional polyol esters, have good compatibility over a wide range, and a high-performance polyol ester having extremely excellent hydrolysis resistance and fluidity can be obtained. Among the polyol esters obtained from existing fatty acids and polyhydric alcohols, no high-performance polyol esters which can be used for the above-mentioned alternative CFCs at a kinematic viscosity at 40 ° C. in the range of 28 to 40 cst have not been found. The polyol ester-based lubricating oil of the present invention has extremely excellent performance as a lubricating oil such as a refrigerator oil, and the industrial significance of the present invention is great.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification number Agency reference number FI Technical display location C10N 20:00 20:02 30:00 30:08 40:30

Claims (12)

[Claims] A) An acid having 6 to 17 carbon atoms in which an α-carbon of an acid residue is tertiary-branched, and wherein all alkyl groups having 4 or more carbon atoms connected to the α-carbon have at least one branch. A polyol ester composed of an alcohol residue of neopentyl polyol, and B) the α-carbon of the acid residue has 2 carbon atoms.
Is a mixture of an acid residue having 6 to 17 carbon atoms, in which the alkyl group connected to the α-carbon is all linear, and a polyol ester composed of an alcohol residue of neopentyl polyol. And a kinematic viscosity at 40 ° C. in the range of 28 to 40 cst. 2. The polyol ester lubricating oil according to claim 1, wherein the polyol ester of A) is 70 to 85% by weight and the polyol ester of B) is 15 to 30% by weight. 3. The polyol ester of A) is of the general formula (I)
And is represented by The polyol ester satisfying 5 ≦ m ≦ 8 and 5 ≦ n ≦ 8 is 52.0 to 58.0% by weight, 5 ≦ m ≦ 8 and 8 <n
The polyol ester satisfying ≦ 16 is 38.0 to 44.0.
% By weight, a polyol ester having 8 <m ≦ 16 and 8 <n ≦ 16 is a mixture of 3.0 to 7.0% by weight,
The polyol ester of B) is represented by the general formula (II): 93.0-97.0% by weight of a polyol ester satisfying 5 ≦ m ≦ 8 and 5 ≦ n ≦ 8, 5 ≦ m ≦ 8 and 8 <n
The polyol ester having ≦ 16 is a mixture of 3.0 to 5.0% by weight, and the polyol ester having 8 <m ≦ 16 and 8 <n ≦ 16 is a mixture of 0.1 to 4.0% by weight. Polyol ester-based lubricating oil. 4. The polyol ester lubricating oil according to claim 2, which has a pour point of -40 ° C. or lower. 5. A catalyst comprising iron, copper and aluminum,
Pre-moisture 1000ppm or less, acid value 0.01mgKOH
3. The sample according to claim 2, wherein the acid value after sealing the sample and 1,1,1,2-tetrafluoroethane and heating at 200 ° C. for 28 days is 0.02 mgKOH / g or less. Polyol ester lubricating oil. 6. A 1,1,1,2-tetrafluoroethane /
The polyol ester-based lubricating oil according to claim 1, wherein the two-phase separation temperature when the polyol ester-based lubricating oil is mixed at a weight ratio of 9/1 is -60C or less on a low temperature side and 100C or more on a high temperature side. 7. A weight ratio of difluoromethane / pentafluoroethane / 1,1,1,1,2-tetrafluoroethane is 23.
/ 25/52 freon mixture and polyol ester lubricating oil are mixed at a weight ratio of 9/1 flon mixture / polyol ester lubricating oil. The polyol ester-based lubricating oil according to claim 2, which is 80 ° C or higher. 8. A mixture obtained by mixing a fluorocarbon mixture of a mixture of difluoromethane / pentafluoroethane at a weight ratio of 50/50 and a polyol ester-based lubricating oil at a weight ratio of 9/1 of a fluorocarbon mixture / polyolester-based lubricating oil. The polyol ester-based lubricating oil according to claim 2, wherein the phase separation temperature is -30C or less on a low temperature side and 60C or more on a high temperature side. 9. A composition for a working fluid of a refrigerator, comprising a mixture of the polyol ester-based lubricating oil of claim 1 and difluoromethane, pentafluoroethane and 1,1,1,2-tetrafluoroethane. 10. The working fluid according to claim 9, wherein the weight ratio of difluoromethane / pentafluoroethane / 1,1,1,2-tetrafluoroethane is 15-30 / 15-30 / 50-70. Composition for 11. A composition for a working fluid of a refrigerator comprising a mixture of the polyol ester-based lubricating oil of claim 1 and difluoromethane and pentafluoroethane. 12. The method according to claim 1, wherein the weight ratio of difluoromethane / pentafluoroethane is 40-50 / 50-60.
The composition for a working fluid of a refrigerator according to 1 above