JPH11279579A - Preparation of grease - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a grease of a high commercial value having a high dropping point and fine texture by forming a metallic soap by mixing a dispersant and a monocarboxylic acid with a base oil and adding to the resultant mixture an aqueous solution of a metal containing an aromatic dicarboxylic acid previously dissolved. SOLUTION: Concretely, a dispersant and a monocarboxylic acid are mixed with a base oil and heated. To the mixture, an aqueous solution of a metal, in which an aromatic dicarboxylic acid is previously dissolved at a temp. of 80-110 deg.C, to form a metallic soap, which is subjected to the dehydration at a temp. of 90-110 deg.C and subsequently to the heat treatment at a temp. of 180-215 deg.C and then cooled down. As the aromatic dicarboxylic acid there can be employed one having 8-26 carbon atoms. The amount of the aromatic dicarboxylic acid employed is usually 0.5-20 pts.wt. based on 100 pts.wt. of the raw materials. As the metallic base material is especially preferable lithium hydroxide, monohydrate thereof of lithium carbonate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing grease, and more particularly to a method for producing grease having a high dropping point, a good grain, and a high commercial value.

[0002]

2. Description of the Related Art Grease is widely used in various machines such as automobiles, electric equipment, construction machines, and machine tools. In recent years, grease has been required to be smaller, have higher output, be lighter, and have easier maintenance. Grease lubrication conditions are becoming increasingly severe. The downsizing and high output of the machine means that the size and shape become smaller even with the same output, but when the size and shape become smaller,
Since the amount of heat released from the machine surface decreases, the temperature of the lubricated portion increases. Lighter weight also encourages the use of materials that are less conductive to heat, such as non-metals, which further increases temperature. Therefore, there is a demand for a grease having a high dropping point and having lubricity even at a high temperature. To cope with such a problem, various methods for producing high drop point grease have been proposed. For example, Japanese Patent Publication No. 63-19560 discloses that a detergent and dispersant is dissolved in a base oil, and a hydroxy fatty acid and lithium hydroxide are added thereto to produce a lithium soap of the hydroxy fatty acid, and then an aliphatic dicarboxylic acid is added. After that, a method is disclosed in which lithium hydroxide is charged and heating is performed to produce grease. JP-A-54-6002 discloses that a hydroxy fatty acid is added to a base oil and dissolved by heating, and an aqueous solution of lithium hydroxide is added thereto to cause a saponification reaction.
A method for producing grease in which an aromatic carboxylic acid and / or a lithium salt of an aromatic carboxylic acid is further added at a temperature of ° C. is disclosed.

[0003]

However, in a situation where the requirements for lubrication conditions have become more and more severe as in recent years, the above-mentioned prior art is still not enough and a grease having a higher drop point is required. . That is, an object of the present invention is to provide a method for producing grease having a high dropping point, a good grain (texture) and a high commercial value.

[0004]

The present inventors have conducted intensive studies to obtain grease having a high dropping point. As a result, after surprisingly dissolving an aromatic dicarboxylic acid in an aqueous metal solution,
By adding to the mixed system of base oil, monocarboxylic acid and dispersant, the metal soap is uniformly dispersed and has a high dropping point, and the solids (soap particles) are greatly reduced and the grain is excellent. The present inventors have found that grease having a high commercial value can be obtained, and reached the present invention. That is, the present invention is a method for producing grease, in which a dispersant and a monocarboxylic acid are mixed with a base oil, and an aqueous metal solution in which an aromatic dicarboxylic acid is dissolved in advance is added thereto to produce a metal soap. In particular, the present invention, after mixing the base oil, dispersant, monocarboxylic acid and then heating,
At a temperature of 80 to 110 ° C., an aqueous metal solution in which an aromatic dicarboxylic acid is previously dissolved is added to generate a metal soap, and 9
Dehydration by treating at 0 to 110 ° C., then 180 to 2
This is a method for producing grease, which is subjected to heat treatment at 15 ° C. and then cooling.

[0005]

Embodiments of the present invention will be described below. The base oil used in the present invention is not particularly limited, and any of various conventionally known mineral oils and synthetic oils can be used.For example, paraffinic, intermediate or naphthenic mineral oils and the like can be used. Solvent refinement of mineral oil, refined mineral oil hydrorefined, or hydrocarbon-based synthetic oils such as α-olefins, oils and fats, synthetic esters,
Synthetic ethers and the like can be used. Among these, refined mineral oil and synthetic oil are preferred. The kinematic viscosity of the base oil is not particularly limited, but is usually 5 to 500 cs at 40 ° C.
t, preferably from 5 to 400 cst. Here, as a method for preparing mineral oil, for example,
In the case of naphthenic base crude oil, a refined oil preparation means for purifying a distillate obtained by atmospheric distillation or a residual oil obtained by atmospheric distillation under reduced pressure according to an ordinary method is employed. The purification method at this time is not particularly limited, and various purification methods can be employed. Usually, hydrogenation treatment, solvent extraction treatment, alkali distillation, sulfuric acid washing treatment, and clay treatment are performed alone or in an appropriate order. Further, the same processing can be performed in a plurality of stages. Specifically, a method of hydrotreating a distillate in two stages, a method of treating a distillate with a solvent and then hydrotreating the same,
And the like.

[0006] In the case of paraffin-based crude oil and intermediate-based crude oil, distillate obtained by distilling paraffin-based crude oil or intermediate-based crude oil under normal pressure or distilling residual oil obtained by atmospheric distillation under reduced pressure is usually used. A refined oil preparation means for purifying according to the method or a deeply dewaxed oil preparation means for further performing a deep dewaxing treatment after the purification is employed. The purification method at this time is not particularly limited, and various purification methods can be employed. Usually, hydrogenation treatment, dewaxing treatment (solvent dewaxing, hydrodewaxing), solvent extraction treatment,
The alkali distillation, the sulfuric acid washing treatment, and the clay treatment are performed alone or in an appropriate order. Further, the same processing can be performed in a plurality of stages. Specifically, a method of dewaxing after hydrogenation, a method of hydrotreating, hydrodewaxing, and a further hydrogenation, solvent extraction, solvent removal of the raffinate, and hydrogenation And the like.

The base oil used in the present invention can be prepared by the above-mentioned various methods. For example, the following general properties can be used. (1) Kinematic viscosity (40 ° C.) 5 to 500 cst (2) Viscosity index 10 to 140 (3) Total acid value 0.001 to 1 mgKOH / g (4) Basic nitrogen content 150 PPM or less, particularly less than 7 PPM (5) Bromine Value 100 g / 100 g or less, especially 0.1 to 40 g / 100 g (6) Iodine value 0 to 20 (7) Density 0.84 to 0.93 g / cm ³ (8) Ring analysis (ndM method) Total aroma content 0 20% (% CA) Total cyclic content 25-45% (% CR) Total naphthene content 25-45% (% CN) Total paraffin content 50-75% (% CP) (9) Aniline point 85-150 ° C ( 10) Pour point -5 to -45 ° C (11) S content 50 PPM or less, particularly 10 PPM or less (12) N content 300 PPM or less, particularly 5 PPM or less (13) Number average molecular weight 200 to 1000

[0008] The amount of the base oil used in the raw material is usually 30 to 90 parts by weight with respect to 100 parts by weight of the raw material, and when the base oil is divided and used, the total amount is used. Of course, a plurality of types of base oils may be used. If the kinematic viscosity is smaller than the above range, the heat resistance may be insufficient and the lubrication life may be insufficient. If the kinematic viscosity is larger than the above range, the fluidity may be insufficient.

As the dispersant in the present invention, a sulfonate, salicylate, phenate or phosphonate of an alkali metal or alkaline earth metal can be used regardless of whether it is basic or neutral. Here, examples of the alkali metal include lithium, sodium, and potassium.
Calcium, magnesium, and alkaline earth metals
Barium and the like can be mentioned. Of these, sulfonates of barium, calcium or sodium are preferred. As other dispersants, sulfonic acid, succinimide, borated succinimide obtained by treating the succinimide with a boron compound, and the like can also be preferably used. These may be used alone or in combination. Examples of such a combination include barium sulfonate and calcium sulfonate, calcium sulfonate and sodium sulfonate, and barium sulfonate and sodium sulfonate. This dispersant is used to uniformly disperse the produced metal soap in the grease or to disperse oils and insolubles generated during use of the grease. This dispersant is preferably added before or during the production of the metal soap. The resulting metallic soap is evenly and finely dispersed in the grease. If the amount of the dispersant is too small, the above effect cannot be expected, and if the amount is too large, the water resistance may be deteriorated. Therefore, it is preferable to use these in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of the raw material.

The monocarboxylic acid used in the present invention preferably has 12 to 30 carbon atoms, more preferably 16 to 24 carbon atoms. The monocarboxylic acids also include hydroxymonocarboxylic acids. When the number of carbon atoms of the monocarboxylic acid is less than the above range, the amount used for grease becomes large, which is uneconomical. When the number of carbon atoms is larger than the above range, it does not hinder grease formation, but it is not general-purpose and therefore expensive, which is also uneconomical. Specific examples of these monocarboxylic acids include stearic acid, 9-hydroxystearic acid, 10-hydroxystearic acid, 12-hydroxystearic acid, and the like, with 12-hydroxystearic acid being particularly preferred. The monocarboxylic acid reacts with the metal base material and plays a role of a thickener mainly in metal soap. The used amount is usually 3 to 20 parts by weight based on 100 parts by weight of the raw material.

In the production method of the present invention, an aromatic dicarboxylic acid is dissolved in an aqueous metal solution in advance. As such an aromatic dicarboxylic acid, an aromatic dicarboxylic acid having 8 to 26 carbon atoms can be used. Specific examples include terephthalic acid, phthalic acid, isophthalic acid, naphthalenedicarboxylic acid and the like, with terephthalic acid being particularly preferred. The aromatic dicarboxylic acid reacts with the metal base in the aqueous metal solution, and the metal soap, which is a salt thereof, is uniformly and finely dispersed in the grease, so that the dropping point is significantly improved. From this point, the amount used is usually 0.5 part by weight per 100 parts by weight of the raw material.
-20 parts by weight. The metal substrate is not particularly limited as long as it contains a metal and reacts with a monocarboxylic acid or an aromatic dicarboxylic acid to form a salt. Examples of the metal include lithium, sodium, calcium, and magnesium. Specific examples of the metal substrate include metal hydroxides and metal carbonates, and among them, lithium hydroxide, its monohydrate and lithium carbonate are preferred. The metal base material is used for saponifying a monocarboxylic acid and an aromatic dicarboxylic acid to produce a metal soap, and is usually 1 to 20 parts by weight based on 100 parts by weight of the raw material. It is preferably used in an amount of about 1 to 1.1 times equivalent of the total equivalent with the group dicarboxylic acid.

Next, a method for producing grease using these raw materials will be described. In the present invention, first,
The dispersant and the monocarboxylic acid are added to the base oil, and 80 to 100
Heat to ° C. Usually, it is performed while stirring to uniformly mix. Further, an aqueous metal solution in which an aromatic dicarboxylic acid is dissolved is prepared in advance. This is prepared by dissolving the metal substrate in water and then dissolving the aromatic dicarboxylic acid. The dicarboxylic acid used here may be all or part of the amount used for grease production.
Water is preferably used in an amount of 5 to 10 times the weight of the dicarboxylic acid. In addition, since water is eventually dehydrated, 1
Not included in 00 parts by weight. By pouring the thus obtained metal aqueous solution into a mixed system of a base oil, a dispersant and a monocarboxylic acid, the metal base material is appropriately dispersed, and the metal soap is uniformly generated and dispersed in the grease. Can,
As a result, a grease having a high dropping point and excellent in graininess (texture) with less solid matter (soap particles) and high commercial value can be obtained.

A base oil previously heated from the aqueous metal solution,
The temperature at which the dispersant and the monocarboxylic acid are charged into the mixed system is usually 80 to 110 ° C, preferably 90 to 100 ° C. The saponification reaction is carried out at this temperature for about 30 minutes to 3 hours. By adding a metal aqueous solution in which an aromatic dicarboxylic acid is dissolved to a mixed system of a base oil, a dispersant, and a monocarboxylic acid, the metal soap is uniformly finely dispersed in the grease. Here, it is assumed that the metal soap is partially produced as a complex metal soap. Next, grease is prepared by a conventional method. That is, first, the obtained metal soap is dehydrated. The temperature is usually 90-11
0 ° C. The dehydration time may be determined as appropriate, but is usually 1
~ 5 hours. Then, to perform dehydration better,
Heat to 80-215C, preferably 195-210C. Hold at the maximum temperature for about 5 to 20 minutes, then cool. On the way, 0 to 70 parts by weight may be added to 100 parts by weight of the raw material using a diluent oil or a cooling oil as a base oil. After cooling, in order to stabilize the grease, shearing such as milling is applied to form grease.

In the present invention, various additives such as an antioxidant can be added to improve the performance of the grease. The timing of adding the additive is not particularly limited, but is usually performed after cooling. There is no particular limitation on the antioxidant,
For example, amine-based antioxidants, phenol-based antioxidants and the like can be mentioned. Examples of the amine-based antioxidant include monooctyldiphenylamine; monoalkyldiphenylamine such as monononyldiphenylamine;
4,4'-dibutyldiphenylamine;4,4'-dipentyldiphenylamine;4,4'-dihexyldiphenylamine;4,4'-diheptyldiphenylamine; 4,
4'-dioctyldiphenylamine; dialkyldiphenylamines such as 4,4'-dinonyldiphenylamine, tetrabutyldiphenylamine; tetrahexyldiphenylamine; tetraoctyldiphenylamine; polyalkyldiphenylamines such as tetranonyldiphenylamine, α-naphthylamine; phenyl-α-naphthylamine; Butylphenyl-α-naphthylamine; pentylphenyl-α-naphthylamine; hexylphenyl-α-naphthylamine; heptylphenyl-α-naphthylamine; octylphenyl-α-naphthylamine;
Examples include naphthylamines such as nonylphenyl-α-naphthylamine, and among them, monoalkyldiphenylamine and dialkyldiphenylamine are preferable.

Examples of the phenol antioxidant include 4,4'-methylenebis (2,6-di-t-butylphenol); 4,4'-bis (2,6-di-butylphenol); Bis (2-methyl-6-t-butylphenol); 2,2'-methylenebis (4-ethyl-
2,2'-methylenebis (4-methyl-6-t-butylphenol); 4,4 '
-Butylidenebis (3-methyl-6-t-butylphenol); 4,4'-isopropylidenebis (2,6-di-t-butylphenol); 2,2'-methylenebis (4-methyl-6-nonylphenol); 2,2′-isobutylidenebis (4,6-dimethylphenol);
Bisphenols such as 2,2'-methylenebis (4-methyl-6-cyclohexylphenol), 2,6-di-t
-Butyl-4-methylphenol; 2,6-di-t-butyl-4-ethylphenol; 2,4-dimethyl-6-
t-butylphenol; 2,6-di-t-amyl-p-
Alkyl phenols such as cresol, 2,6-di-t-butyl-4- (N, N'-dimethylaminomethylphenol);4,4'-thiobis(2-methyl-6-t-butylphenol); 4,4 '-Thiobis (3-methyl-6
-T-butylphenol); 2,2'-thiobis (4-
Methyl-6-t-butylphenol); bis (3-methyl-4-hydroxy-5-t-butylbenzyl) sulfide; bis (3,5-di-t-butyl-4-hydroxybenzyl) sulfide; n-octadecyl -3- (4-
(Hydroxy-3,5-di-t-butylphenyl) propionate; 2,2′-thio [diethyl-bis-3-
(3,5-di-t-butyl-4-hydroxyphenyl)
Propionate]. Of these, bisphenols and alkylphenols are particularly preferred. Examples of the metal salt antioxidant include the following general formula (I)

[0016]

Embedded image

(Wherein M is a metal, x is the valence of the metal, R ₁ and R ₂ each represent an alkyl or alkenyl group having 3 to 20 carbon atoms, and R ₁ and R ₂ are the same. May be different.) Specifically,
The following general formula (II)

[0018]

Embedded image

(Wherein R ₁ and R ₂ each have 3 carbon atoms)
Represents up to 20 alkyl groups or alkenyl groups, and R ₁ and R ₂ may be the same or different. ),
More specifically, carbamate antioxidants such as di-n-butylnickel dithiocarbamate, zinc dialkyldithiophosphate, nickel dialkyldithiophosphate, zinc dialkylthiocarbamate, nickel dialkylthiocarbamate and the like can be mentioned. In the present invention, preferably, an amine antioxidant, a phenolic antioxidant, and a carbamate antioxidant are used. It is particularly preferable to use an amine type and a carbamate type together. As a result, the antioxidant performance is remarkably exhibited, and the oxidation life is extended. If the amount of the antioxidant is too small, a desired antioxidant effect cannot be obtained, and if it is too large, deterioration is accelerated. For this reason, it can be usually 0.1 to 10 parts by weight, preferably 0.2 to 5 parts by weight, per 100 parts by weight of the raw material.

Other additives that can be incorporated in the grease production method of the present invention include, for example, rust inhibitors, sorbitan esters, oxidized waxes and metal salts thereof, and lanolinic acid soaps. Examples of the agent include sulfurized fats and oils, sulfurized mineral oil, phosphite, acid phosphate, and the like. Examples of the oily agent include phosphate, fatty acid, dithiocarbamic acid and metal salts thereof, and metal salts of dialkyldithiophosphate. In the present invention, other additives can be further blended according to the purpose, and examples thereof include dyes and fragrances. The amount of these components is usually 0.001 to 10 parts by weight in the raw material. In addition, some dithiocarbamate-based antioxidants include
Some are available as oily agents, and some dispersants
Some can be used as detergents and rust inhibitors. In the present invention, these additives that perform a plurality of functions can be used in appropriate combination.

[0021]

EXAMPLES Next, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. Various Performance Test Methods in Examples and Comparative Examples (1) Consistency Measured in accordance with JISK-2220. (2) Dropping point Measured according to JIS K-2220. (3) Accelerated oxidation test Measured at a test temperature of 125 ° C. in accordance with JIS K-2220. That is, using a grease oxidation stability tester, 5% by weight of copper powder was added to the prepared grease, and oxygen was added to 0.1 g.
It was sealed at 755 MPa, and the time required for a sudden pressure drop at 125 ° C. was measured, and this was defined as the oxidation life. (4) Bearing life test (ASTM D1741) Using a 6306 bearing, a specified load (thrust: 40 lb)
s, 25 lbs), 125 ° C., 20-hour operation / 4-hour stop cycle, and the number of hours during which operation was impossible due to seizure when operating at 3500 rpm was measured. (5) Solids (Soap Particles) A thin film of grease (thickness 0.5 mm) was prepared, and the number of solids having a size of 75 μm or more per unit area (1 cm ² ) was measured.

Properties of Raw Oil in Examples and Comparative Examples Properties of Base Oil I (1) Viscosity (40 ° C.) 91 cst (2) Viscosity index 107 (3) Total acid value 0.01 mgKOH / g (4) Basic nitrogen content 3 PPM or less (5) Bromine value 0.2 g / 100 g (6) Iodine value 0 (7) Density (15 ° C.) 0.869 g / cm ³ (8) Ring analysis (ndM method) Total aroma 0% (% CA) Total cyclic 28% (% CR) Total naphthene 28% (% CN) Total paraffin content 72% (% CP) (9) Aniline point 125 ° C (10) Pour point -17.5 ° C (11) S content 3PPM (12) N content 5PPM or less (13) Number average Molecular weight 561

2. Properties of Base Oil II (1) Kinematic viscosity (40 ° C.) 409 cst (2) Viscosity index 107 (3) Total acid value 0.01 mg KOH / g (4) Basic nitrogen content 3 PPM or less (5) Bromine value 0.3 g / 100 g (6) Iodine value 1 or less (7) Density (15 ° C.) 0.879 g / cm ³ (8) Ring analysis (ndM method) Total aroma 0% (% CA) Total cyclic 27% (% CR) Total Naphthene content 27% (% CN) Total paraffin content 73% (% CP) (9) Aniline point 143 ° C (10) Pour point -15 ° C (11) S content 2PPM (12) N content 5PPM or less (13) Number average Molecular weight 760

Examples 1 to 5 As shown in Table 1, a dispersant, 12-hydroxystearic acid, was mixed with a base oil I, and the mixture was heated to 95 ° C. and uniformly mixed. Then, first
The terephthalic acid was previously converted to lithium hydroxide
A saponification reaction is carried out by adding a lithium aqueous solution obtained by dissolving a monohydrate aqueous solution (an aqueous solution obtained by dissolving lithium hydroxide / monohydrate in water 7 times the weight of terephthalic acid) and keeping the temperature at about 95 ° C. And dehydrated. Then, with stirring,
The temperature was kept at 05 ° C. for 2 hours to uniformly disperse the produced metal soap. Thereafter, the mixture was heated to 205 ° C., after which base oil II was added, the mixture was cooled to 130 ° C., an antioxidant was added, and the mixture was stirred, followed by milling to obtain grease. Table 1 shows the properties of the obtained grease. Table 1 shows the results of the performance test for each grease.

Comparative Example 1 A grease was obtained in the same manner as in Example 1 except that azelaic acid was previously added to the base oil. Table 1 shows the properties and the results of the performance tests. Comparative Example 2 The procedure of Example 1 was repeated, except that phthalic acid was used instead of terephthalic acid, and the whole amount was added together with 12-hydroxystearic acid. Table 1 shows the grease properties and performance test results.

[0026]

[Table 1]

[0027]

[Table 2]

* 1: Paraffin-based two-stage hydrotreated refined mineral oil (kinematic viscosity at 40 ° C. 91 cSt) * 2: Paraffin-based two-stage hydrotreated refined mineral oil (40 ° C.)
* 3: Ca sulfonate (Example 1), Na sulfonate (Examples 2 to 4, Comparative Examples 1 and 2) * 4: 12-hydroxystearic acid * 5: Terephthalic acid (Examples 1 to 4) ), Isophthalic acid (Example 5), azelaic acid into base oil (Comparative Example 1), phthalic acid into base oil (Comparative Example 2) * 6: dinonyldiphenylamine * 7: nickel dibutyldithiocarbamate

[0029]

According to the method of the present invention, grease having a high dropping point, a small amount of solids and a high commercial value can be obtained. Therefore, the grease obtained by the production method of the present invention can be suitably used for bearings, general-purpose motor grease, and the like.

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Isao Mamiya 1-34-22 Sakashita, Itabashi-ku, Tokyo Chuo Yuka Co., Ltd. (72) Inventor Kazuo Kato 1-34-22 Sakashita, Itabashi-ku, Tokyo Central Yuka Co., Ltd.

Claims (6)

[Claims] 1. A method for producing a grease in which a dispersant and a monocarboxylic acid are mixed with a base oil, and an aqueous metal solution in which an aromatic dicarboxylic acid is previously dissolved is added to the mixture to produce a metal soap. 2. Mixing a base oil, a dispersant, and a monocarboxylic acid, heating the mixture, and adding a metal aqueous solution in which an aromatic dicarboxylic acid is previously dissolved at a temperature of 80 to 110 ° C. to produce a metal soap. And treated at 90-110 ° C. to perform dehydration,
Then, a method for producing grease in which heat treatment is performed at 180 to 215 ° C. and then cooling is performed. 3. The method for producing grease according to claim 1, wherein the aromatic dicarboxylic acid is terephthalic acid. 4. The method for producing grease according to claim 1, wherein the aqueous metal solution is obtained by dissolving lithium hydroxide monohydrate in 5 to 10 times the weight of terephthalic acid together with terephthalic acid. . 5. A kinematic viscosity at 40 ° C. of 5 to 500 cs.
The method for producing grease according to any one of claims 1 to 4, wherein the mineral oil or the synthetic oil t is used as a base oil, the monocarboxylic acid is 12-hydroxystearic acid, and the metal of the aqueous metal solution is lithium. 6. The method for producing grease according to claim 1, wherein an antioxidant is added after the metal soap is formed.