JPH08134483A - Base oil for lubricating oil - Google Patents

Abstract

PURPOSE: To obtain a lubricating oil base which is soluble in water, has high biodegradability, and does not cause environmental pollution by using as the main ingredient a compound obtained by reacting a specific polyglycol with a specific polycarboxylic acid under specific conditions. CONSTITUTION: The base oil comprises as the main component a compound which has a pour point of 0 deg.C or lower and is obtained by reacting at least one polyglycol selected among polyoxyalkylene glycols represented by formula I (wherein R<1> is a 2-4C alkylene and a is 2-50) and polyoxyalkylene glycerol ethers represented by formula II [wherein R<2> to R<4> each is the same as R<1> and b, c, and d each is 2-46, provided that 6<=(b+c+d)<=50] with a 3-10C aliphatic polycarboxylic acid (e.g. adipic acid) in a ratio of -COOH equivalents to -OH equivalents of 0.8 or lower. This base oil dissolves in water in any proportion.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lubricating base oil which dissolves in water at an arbitrary ratio and is biodegradable.

[0002]

2. Description of the Related Art Processing oils such as cutting oils, grinding oils and press oils,
Also, with regard to lubricating oils used in various machines such as hydraulic oils used in forests, rivers, lakes, etc., part of the lubricating oil often flows out to rivers, oceans, and soils depending on the conditions of use. However, mineral oils and various synthetic oils that have been widely used as these lubricating oils have a structure that is difficult to decompose in the natural world, resulting in marine pollution, water pollution, soil pollution, and environmental and natural destruction. In addition, polyalkylene glycol-based oils and the like, which are often used in water-soluble type, have a structure that is difficult to decompose in nature in order to improve their stability and lubricity. As a countermeasure for this, hydraulic oils and the like having excellent coagulation-sedimentation processability in wastewater treatment facilities have been developed, but they cannot necessarily solve these problems. For this reason, biodegradable lubricating oils that are more easily decomposed in the natural world have been demanded.

[0003]

In view of the above problems, the present invention is to provide a lubricating base oil which dissolves in water at an arbitrary ratio and has excellent biodegradability.

[0004]

As a result of various studies to achieve the above object, the present invention has found that a specific ester can achieve the above object, and has solved the present invention.

That is, the present invention has the general formula [1]

Embedded image [In the formula, R ¹ is an alkylene group having 2 to 4 carbon atoms, and a is 2 to 5
Represents an integer of 0] and a general formula [2]

[Chemical 4] [Wherein R ² , R ³ and R ⁴ are alkylene groups having 2 to ⁴ carbon atoms, b, c and d are integers of 2 to 46, and 6 ≦ b
+ C + d ≦ 50 is an integer], and one or more polyglycol selected from the group consisting of polyoxyalkylene glycerol ethers and a total carbon number of 3 to 1
A compound obtained by reacting an aliphatic polycarboxylic acid of 0 with a (-COOH equivalent) / (-OH equivalent) ratio of 0.8 or less and a pour point of 0 ° C or less is mainly used. The present invention relates to a water-soluble biodegradable lubricating base oil as a component.

The term "water-soluble" as used in the present invention means that, when water and a base oil are mixed in an arbitrary ratio, they do not separate into two layers or become cloudy in a temperature range of at least 0 ° C to 30 ° C, preferably -10 ° C to 50 ° C. are doing.

The biodegradability evaluation in the present invention is carried out according to the official conditions of the MITI method using a coulometer (closed system oxygen consumption measuring device) in the Chemical Substances Control Law, and oxygen consumption 14 days after the substrate (lubricating base oil). It was confirmed by measuring the ratio between the amount and the theoretical oxygen demand.

In general, when the biodegradability is examined by the oxygen consumption, it is very rare that the oxygen consumption and the theoretical oxygen demand coincide with each other. The reason for this is that when the substrate undergoes biodegradation, the microorganism decomposes the substrate and at the same time, it has the action of assimilating the degrading substance into a part of the bacterial cell. It is considered that the product accumulates in the reaction solution.

Therefore, in general, the oxygen consumption of the substrate is 35-40% of the theoretical oxygen demand, that is, the degree of biodegradation is 35-35.
It has been suggested that if it is 40%, it is a completely degradable compound in which the presence of intermediate products is hardly recognized (Mitsunobu Mitsunobu, Petroleum and Microorganisms 14, 142 (1975)).

CEC (European Standards Advisory Committee) standard L-33-T-, which is currently published as a biodegradability evaluation test.
In the test according to 82, if the decomposition rate is 67% or more, it is generally recognized as a biodegradable oil,
It is also reported that if the degree of decomposition is more than 67%, it corresponds to 67% or more of the CEC standard (M.Kagaya, M.Ishimar.
u, SAE Paper911277). Therefore, the term "biodegradability" in the present invention means that the degree of biodegradation measured according to the MITI method is 40% or more.

The polyglycol in the present invention has the general formula [1]

Embedded image And a polyoxyalkylene glycol represented by the general formula [2]

[Chemical 6] Is one or a mixture of two or more selected from the group consisting of polyoxyalkylene glycerol ethers represented by
22 is an integer, and b, c and d are integers of 2 to 46 and 6 ≦ b + c + d ≦ 50, preferably 2 to 18 and 6 ≦ b + c + d ≦ 22.
Indicates an integer. R ¹ , R ² , R ³ and R ⁴ have 2 to 2 carbon atoms.
4 represents an alkylene group.

Specific examples of the alkylene group (R ¹ , R ² , R ³ and R ⁴ ) include ethylene group (-CH ₂ CH _2- ), propylene group (-CH (CH ₃ ) CH _2- ), Trimethylene group (-CH ₂ CH ₂ CH
₂ -), butylene _{(-CH (CH 2 CH 3)} CH 2 -), 1,2 -dimethylethylene group _{(-CH (CH 3) CH 2} (CH 3) -), 1 -methyltrimethylene group (-CH (CH ₃ ) CH ₂ CH _2- ), 2-methyltrimethylene group (-CH ₂ CH (CH ₃ ) CH _2- ), tetramethylene group (-CH ₂ CH ₂ CH ₂ C)
H _2- ) and the like, and particularly from the viewpoint of water solubility and biodegradability of a reaction product with an aliphatic polycarboxylic acid, an ethylene group is
A propylene group and a butylene group are preferable from the viewpoint of the pour point.
a or b + c + d is greater than 50, or R ¹ ,
When the number of carbon atoms of R ² , R ³ and R ⁴ is larger than 4, the reaction product with the aliphatic polycarboxylic acid may have a high pour point or poor water solubility or biodegradability, which is not preferable.

When R ¹ , R ² , R ³ and R ⁴ are ethylene groups and a or b + c + d is larger than 22, the pour point of the reaction product with the aliphatic polycarboxylic acid becomes 0 ° C. or higher, and R ^{When 1} , R ² , R ³ and R ⁴ are other than ethylene groups and a or b + c + d is larger than 17, the water solubility of the reaction product with the aliphatic polycarboxylic acid may be deteriorated.
In this case, it is preferable to use a mixture of two or more different polyglycols, and the mixing ratio differs depending on the type and molecular weight of the polyglycol.

Further, the polyglycol in the present invention may have alkylene groups having different carbon numbers in the molecule.
That is, the oxyalkylene group may be a random copolymer or a block copolymer. In this case, from the viewpoint of water solubility, biodegradability and low temperature fluidity, a copolymer of an ethylene group and an alkylene group other than that is preferable, and a copolymer of an ethylene group and a propylene group is particularly preferable.

The aliphatic polyvalent carboxylic acid in the present invention is a saturated or unsaturated carboxylic acid having a valence of 2 or more and may have a hydroxyl group in the molecule. The total number of carbon atoms is 3 to 10, preferably 4 to 6. When the total carbon number is less than 3, the stability of the product is poor, and when it is more than 10, the water solubility and biodegradability are poor. Specifically, for example, malonic acid,
Methylmalonic acid, succinic acid, maleic acid, malic acid, ethylmalonic acid, dimethylmalonic acid, methylsuccinic acid, glutaric acid, adipic acid, 2,2-dimethylsuccinic acid,
2,2,3-trimethylsuccinic acid, 2-methylglutaric acid, butylmalonic acid, diethylmalonic acid, 2,2-dimethylglutaric acid, 2,4-dimethylglutaric acid, 3,3
-Dimethyl glutaric acid, 2-ethyl-2-methyl succinic acid, 3-methyl adipic acid, pimelic acid, suberic acid,
2,2-dimethyladipic acid, azelaic acid, sebacic acid and the like can be mentioned, and lower alkyl esters and acid anhydrides of these compounds can be similarly used.

The reaction product of the polyglycol and the aliphatic polycarboxylic acid in the present invention is synthesized by a usual esterification reaction. By changing the type and ratio of this polyglycol and the aliphatic polycarboxylic acid, an acid value of 5 KOHm
A product having a g / g or less, a hydroxyl value of 30 to 500 KOHmg / g, and a pour point of 0 ° C. or less is obtained, and a pour point of −30 ° C. or less depending on the combination of polyglycol and aliphatic polycarboxylic acid. You can get the one that shows sex. (-COOH equivalent) / (-OH
When the ratio of (equivalent weight) is higher than 0.8, the pour point becomes high and in some cases it becomes solid, which is not preferable as a lubricating oil.

These reaction products may be mixed with mineral oils and synthetic oils such as poly-α-olefins, alkylbenzenes, esters, polyethers, and phosphoric acid esters as long as the water solubility and biodegradability are not impaired. Additives such as antioxidants, extreme pressure agents, rust preventives, anticorrosives and defoamers may be mixed. Further, water such as ion-exchanged water can be mixed.

[Examples] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[0019]

【Example】

Examples 1 to 6 and Comparative Examples 1 to 4 Table 1 shows the properties of the base oils used in Examples and Comparative Examples.
Table 2 shows the results of evaluation of water solubility and biodegradability.
In addition, these evaluations were performed by the following methods.

Pour point: JIS K2269

Kinematic viscosity: JIS K2283

Water solubility: Examples 1 to 6 and Comparative Examples 1 to 1
A liquid prepared by mixing 10, 30, 50, 70 and 90 parts by weight of distilled water with the base oil of 4 was gradually cooled or heated from room temperature, and the temperature when the mixed liquid separated into two layers or became cloudy was measured, Obtain the minimum separation temperature (LCST) at high temperature and the maximum separation temperature (UCST) at low temperature.

Biodegradability: Standard activated sludge (obtained from the Chemicals Inspection Society of Japan) mixed and collected from 10 or more rivers, lakes, seas and sewage treatment plants nationwide in accordance with the MIT test method 301C modified MITI test method. Was used to measure the oxygen consumption after 14 days with a coulometer to calculate the degree of biodegradation. Biodegradability (%) = [(BOD-B) / TOD] × 10
0 BOD: oxygen consumption of base oil B: basic respiration of sludge TOD: theoretical oxygen demand necessary for complete oxidation of base oil

[0024]

As described above, the lubricating base oil of the present invention has a low pour point and excellent water solubility and can be widely used as various lubricating oils such as hydraulic oils, cutting oils, grinding oils and press oils. Moreover, since it has high biodegradability, it can provide a lubricating oil that does not pollute the global environment.

[0025]

[Table 1]

[Table 2]

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Claims (1)

[Claims] 1. A compound of the general formula [1] [In the formula, R ¹ is an alkylene group having 2 to 4 carbon atoms, and a is 2 to 5
Represents an integer of 0] and a polyoxyalkylene glycol represented by the general formula [2] [Wherein R ² , R ³ and R ⁴ are alkylene groups having 2 to ⁴ carbon atoms, b, c and d are integers of 2 to 46, and 6 ≦ b
+ C + d ≦ 50 is an integer], and one or more polyglycol selected from the group consisting of polyoxyalkylene glycerol ethers and a total carbon number of 3 to 1
A compound obtained by reacting an aliphatic polycarboxylic acid of 0 with a (-COOH equivalent) / (-OH equivalent) ratio of 0.8 or less and a pour point of 0 ° C or less is mainly used. Water-soluble biodegradable lubricating base oil