JPH04164993A - Neopentyl-type complex ester and lubricating oil - Google Patents

Abstract

PURPOSE:To increase, without degrading oxidation stability, the low temperature fluidity and viscosity index of a lubricating oil, which are normally low in the case of a lubricating oil made of an ester of a tertiary fatty acid by employing an ester of neopentyl alcohol with a mixture of a tertiary fatty acid and a dibasic acid. CONSTITUTION:A neopentyl-type complex ester (molecular weight: 270-5,000, acid number: 1mgKOH/g or less, hydroxyl number: 40mgKOH/g or less) which is prepared from a mixture consisting of 60-97mol% (preferably 70-95mol%) tertiary fatty acid of the formula (wherein R represents 1-6C alkyl; and R<1> and R<2> each represent 1-2C alkyl, provided that the total carbon number of R, R<1> and R<2> is 6 or less); 3-40mol% (preferably 5-30mol%) 4-8C dibasic acid (e.g. succinic acid) and neopentyl polyol is employed as a base oil for a lubricating oil which can be advantageously employed as a base oil for a high-- performance engine oil.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a neopentyl type complex ester using a tertiary fatty acid and a dibasic acid as a raw material mixed acid and a neopentyl polyol as a raw material alcohol, and this neopentyl type complex ester. The present invention relates to lubricating oils containing esters.

[Prior Art] Neopentyl polyol esters have been used as lubricant base oils or additives for machines that require excellent oxidation stability, such as aircraft turbine engine oils and automobile engine oils.

However, due to the high performance of machines in recent years, the operating temperature has increased,
Furthermore, with the trend towards long drain lubricating oils, the oxidation stability of conventional neopentyl polyol esters has become insufficient.

US Pat. No. 3,115,519 discloses an ester of neopentyl polyol and a tertiary fatty acid that does not have a hydrogen chain at the α position.

This ester has better oxidation stability than neopentyl polyol ester obtained from a fatty acid with the same number of carbon atoms that is not a tertiary fatty acid, but has a low viscosity index and poor low-temperature fluidity.

US Patent No. 3,282,971 discloses esters of mixed fatty acids of straight chain fatty acids and tertiary fatty acids and neopentyl polyols.

This ester has improved viscosity index and low-temperature fluidity, but
Oxidative stability is inferior to esters that do not contain straight chain fatty acids.

U.S. Patent No. 3,341,574 includes 2.2-
Esters of dimethylpentanoic acid, azelaic acid and neopentyl glycol are disclosed. Although this ester has an improved viscosity index and excellent low-temperature fluidity, it has poor oxidation stability.

In this way, neopentyl polyol ester using tertiary fatty acids has sufficient oxidation stability to be used as a lubricant base oil or additive for machines that operate at high temperatures or require long drains. However, it has the disadvantage of poor viscosity index and low-temperature fluidity.

[Problems to be Solved by the Invention] The present invention provides a neopentyl-type complex ester that improves the low-temperature fluidity and viscosity index of an ester using a tertiary fatty acid without impairing oxidative stability, and a lubricating oil containing the same. The purpose is to

[Means for Solving the Problems] The present invention provides a tertiary fatty acid represented by the first-order general formula [11]
mol% to 97 mol% and 3 mol% of dibasic acid having 4 to 8 carbon atoms
A neopentyl type complex ester having a molecular weight of 270 to 5000 obtained from a mixed acid consisting of ~40 mol% and neopentyl polyol, and a lubricating oil containing this ester.

■ R-C-COOH[Ico■ (wherein, R is an alkyl group having 1 to 6 carbon atoms, R1 and R
2 is an alkyl group having 1 to 2 carbon atoms, and the total number of carbon atoms of R9R' and R2 is 8 or less. ) The tertiary fatty acids represented by the general formula [I] used in the present invention include 2,2-dimethylpropanoic acid, 2゜2-dimethylbutanoic acid, and 2,2-dimethylbutanoic acid.
-dimethylpentanoic acid, 2,2-dimethylhexanoic acid,
2.2-dimethylhebutanoic acid, 2,2-dimethyloctanoic acid.

2-methyl-2-ethylbutanoic acid, 2-methyl-2-ethylpentanoic acid, 2-ethyl-2,3,3-trimethylbutanoic acid, 2,2,3.3-tetramethylpentanoic acid,
Examples include 2,2,3.4-tetramethylpentanoic acid. These tertiary fatty acids may be used alone or
You may use a mixture of two or more types. Especially general formula [1]
It is preferable that R has 2 or 3 carbon atoms. R
When the total number of carbon atoms in 7R1 and R2 exceeds 8, the number of hydrogen atoms derived from methylene groups increases, making it impossible to obtain a neopentyl complex ester having good oxidative stability.

Examples of dibasic acids having 4 to 8 carbon atoms used in the present invention include succinic acid, glutaric acid, adipic acid, pimelic acid, superric acid, 2,2-dimethylsuccinic acid, 2,3-dimethylsuccinic acid, 2,2-dimethylsuccinic acid, and 2,2-dimethylsuccinic acid. -dimethylglutaric acid, 3,3-dimethylglutaric acid, 2,2-dimethyladipic acid, 3,3-dimethyladipic acid, phthalic acid, terephthalic acid, and isophthalic acid. These dibasic acids may be used alone or in combination of two or more. With dibasic acids having 9 or more carbon atoms, the number of hydrogen atoms derived from methylene groups increases, making it impossible to obtain a neopentyl-type complex ester having good oxidative stability. A neopentyl type complex ester having a high viscosity index cannot be obtained with a dibasic acid having 3 or less carbon atoms.

Examples of the neopentyl polyol used in the present invention include neopentyl glycol, trimethylolethane, trimethylolpropane, pentaerythritol, dipentaerythritol, and the like.

These neopentyl polyols may be used alone or in combination of two or more.

The ratio of tertiary fatty acid and dibasic acid used in the present invention is 60 mol% to 97 mol% of tertiary fatty acid.

Preferably it is 70 mol% to 95 mol%. If the ratio of tertiary fatty acids is less than 60 mol%, good oxidative stability cannot be obtained. Moreover, if it exceeds 97 mol%, good viscosity index and low-temperature fluidity cannot be obtained.

The neopentyl type complex ester of the present invention can be obtained by a conventional esterification reaction between neopentyl polyol and a mixed acid of a tertiary fatty acid and a dibasic acid. It can also be obtained by reacting neopentyl polyol with a tertiary fatty acid and reacting the resulting product with a dibasic acid, and it can also be obtained by reacting neopentyl polyol with a dibasic acid. It can also be obtained by reacting with a tertiary fatty acid.

The neopentyl type complex ester in the present invention can also be obtained by using a neopentyl polyol, a tertiary fatty acid, and an acid chloride of a dibasic acid.

The reaction equivalent ratio between the hydroxyl group of the neopentyl polyol and the acyl group of the mixed acid or its acid chloride is not particularly limited, but if the hydroxyl value of the neopentyl type complex ester obtained is too high, the viscosity index may decrease. Therefore, it is generally preferable to use 00 g equivalent or more of acyl group per equivalent of hydroxyl group.

The neopentyl type complex ester obtained by the present invention can be purified by general purification steps such as alkaline water washing, water washing, distillation, and adsorption treatment after the esterification reaction. In terms of oxidative stability, the acid value after purification is 1 mg.
KOH/g or less, hydroxyl value is 40 mg KOH/
It is preferable that it is less than g. Furthermore, when acid chloride is used, if a large amount of chlorine remains, it will cause corrosion, so it is desirable to reduce the chlorine concentration to 10 ppm or less through purification.

The neopentyl type complex ester obtained by the present invention may be used alone as a lubricating oil, or may be used as a lubricating oil, mineral oil, poly-α-olefin, or diester.

It may be used in admixture with other oils such as neopentyl polyol esters, polyphenyl ethers, fluorinated hydrocarbons, phosphoric acid esters, and silicone oils.

In addition, the neopentyl type complex ester of the present invention can be used as a commonly used anti-loading additive, oily agent, and antioxidant.

Various additives such as a detergent dispersant, an antifoaming agent, a rust preventive agent, a demulsifier, a pour point depressant, and a viscosity index improver can be added as necessary.

[Effects of the Invention] The neopentyl complex ester obtained by the present invention has excellent oxidation stability, good low-temperature fluidity, and a high viscosity index.

Therefore, it can be used for engine oil base oils that require these performances, especially engine oil base oils for high-performance engines.
Suitable as engine oil base oil for long drain engines.

It can also be used as grease base oil, electrical insulation oil, refrigeration oil, hydraulic oil, compressor oil, heat medium, etc.

The neopentyl type complex ester of the present invention can sufficiently exhibit its effects even when various conventionally known additives are added thereto.

[Example] The present invention will be explained in more detail with reference to Examples.

Synthesis of Ester An IQ glass back-gate flask with a stirrer was equipped with a suspension tube equipped with a thermometer, a nitrogen blowing tube, and a cooling tube.Table 1
500g of raw material with the composition shown in and P as an esterification catalyst.
-) - Add 1.5 g of luenesulfonic acid and heat at 200°C.
The reaction was allowed to proceed for 0 hours. The reaction product was washed with a 5% aqueous potassium hydroxide solution, washed with water, dehydrated at 95°C and 20 mmHg for 1 hour, and further filtered to obtain ester No.
1~No, 18 (excluding No, 11 and N0015)
I got it.

The equivalent ratio of hydroxyl group to acyl group is 1.0:
All ratios are 1.0:1.5 except for 0.9.

Synthesis using acid chloride was carried out as follows.

Synthesis of Acid Chloride A thermometer, condenser and dropping funnel were attached to a glass back-port flask equipped with an IQ stirrer, and mixed acids were placed in the four-hole flask, and phosphorus trichloride was added dropwise evenly over 1 hour at 40"C. The temperature was maintained for 3 hours. After the reaction product was allowed to stand for 1 hour, the upper layer was separated and distilled to obtain the acid chloride.

Synthesis was carried out using a total of 500 g of mixed acid and phosphorus trichloride at an equivalent ratio of 1.00:1.35.

Synthesis of ester using acid chloride After the neopentyl polyol and mixed acid were reacted by the above method, acid chloride was evenly added dropwise at 50° C. over 1 hour, and the same temperature was maintained for 3 hours. The obtained reaction products were purified in the same manner as above to obtain esters No. 11 and No. 1.
Got 5.

Table 1 shows the acid value, hydroxyl value, kinematic viscosity at 100°C, viscosity index, and pour point molecular weight of each ester.

The molecular weight was determined by vapor pressure equilibrium method.

In Table 1, N5 is 2,2-dimethylpropanoic acid (manufactured by Shell Chemical Co., Ltd.), N6 is 2,2-dimethylbutanoic acid (produced by Shell Chemical Co., Ltd.), and N7 is 2゜2-dimethylpentanoic acid. (manufactured by Shell Chemical Co., Ltd.), N7E is 2-methyl-2-
Ethyl butanoic acid (manufactured by Shell Chemical Co., Ltd.), N9 is 2,2
-Dimethylhebutanoic acid (manufactured by Shell Chemical Co., Ltd.), N10
is 2,2-dimethyloctanoic acid (manufactured by Shell Chemical Co., Ltd.)
, C7 is n-hebutanoic acid (manufactured by Toyo Gosei Co., Ltd.).

D3 is malonic acid (Katayama Chemical Industry Co., Ltd.)
4 is succinic acid (manufactured by Katayama Chemical Industry Co., Ltd.), D5 is glutaric acid (E, 1.DUPONT DE NEMOUR5&
CO, INC), D6 is adipic acid (Kanto Denka Kogyo (Kanto Denka Kogyo)
Co., Ltd.), D8 is superric acid (Wako Pure Chemical Industries, Ltd. 1f)
and p9 indicates Azelain Mt (manufactured by Katayama Chemical Industry Co., Ltd.).

In addition, NPG is neopentyl glycol (Koei Chemical Industry Co., Ltd.)
TMP is trimethylolpropane (manufactured by Koei Chemical Industry Co., Ltd.), PE is pentaerythritol (manufactured by Koei Chemical Industry Co., Ltd.), and DpE is dipentaerythritol (manufactured by Koei Chemical Industry Co., Ltd.). .

Oxidation stability test Oxidation stability test of esters No. 1 to No. 18 by JI
The tests were conducted based on SK 2514 (1980) 3-2 lubricating oil oxidation stability test for internal combustion engines, and changes in total acid value and changes in viscosity were determined.

The results are shown in Table 2.

Table 2 As shown in Tables 1 and 2, the ester No. of the present invention.

Nos. 1 to 11 have excellent oxidation stability, good low temperature fluidity and high viscosity index. Esters No. 12 to No. 18 outside the scope of the present invention are poor in oxidation stability, low-temperature fluidity, or viscosity index.

[Brief explanation of drawings]

FIG. 1 shows ester No. of the present invention obtained in Examples. Figure 2 shows the nuclear magnetic resonance absorption spectrum of ester No. 4 of the present invention. Patent applicant Nippon Oil & Fats Co., Ltd.

Claims (1)

[Claims] 1. 60 mol% to 97 mol% of a tertiary fatty acid represented by the following general formula [I] and 3 mol% to 4 mol% of a dibasic acid having 4 to 8 carbon atoms.
A neopentyl type complex ester having a molecular weight of 270 to 5000 obtained from a mixed acid consisting of 0 mol% and neopentyl polyol. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [I] (In the formula, R is an alkyl group having 1 to 6 carbon atoms, R^1 and R^2 are alkyl groups having 1 to 2 carbon atoms, and R, R ^1
The total number of carbon atoms in and R^2 is 8 or less. ) 2. A lubricating oil containing the neopentyl complex ester according to claim 1.