JP5225354B2 - Grease composition with improved rust and wear resistance - Google Patents

Description

  The present invention relates to a grease composition containing sodium thiosulfate and having improved rust prevention and wear resistance.

Extreme pressure grease with excellent wear resistance and load resistance is often used for bearings, gears, and the like of machinery equipment in automobiles, steel, railways, and other industries.
As an extreme pressure grease composition, various greases contain additives such as sulfurized olefins, sulfurized fats and oils, sulfur-phosphorus extreme pressure agents, molybdenum disulfide, organic molybdenum compounds, lead compounds, and zinc dithiophosphate. This is a typical extreme pressure grease composition.
As a recent technology, Patent Documents 1 to 3 disclose grease compositions containing sodium thiosulfate and having excellent extreme pressure properties.
However, these techniques do not have sufficient wear resistance, and sodium thiosulfate has a hygroscopic property, which may induce rust. In particular, bearings and gears of steel facilities, food machinery, and the like are lubricated under conditions of contact with a large amount of water, so that generation of rust is promoted and lubrication problems are likely to occur.

Japanese Patent Laid-Open No. 3-131690 Japanese Patent Laid-Open No. 11-35965 U.S. Pat. No. 4,923,625

  An object of the present invention is to provide a grease composition that suppresses generation of rust and also improves wear resistance while sufficiently maintaining the extreme pressure property of a grease composition containing sodium thiosulfate.

The present inventors added additives to various greases containing sodium thiosulfate, and conducted rust prevention tests and four-ball tests. The limited additives have a remarkable effect in preventing rust generation and improving wear resistance. As a result, the present invention has been completed.
That is, the first of the present invention is that a grease composition containing 0.05 to 30% by weight of sodium thiosulfate contains (A) calcium sulfonate in an amount of 0.1 to 5% by weight based on the total composition. The grease composition characterized by these.
2nd of this invention is related with the grease composition of Claim 1 which mix | blended 0.1-5 weight% of (B) benzotriazole type compound with respect to the whole composition further.

  In the grease composition of the present invention, any of urea compounds, lithium soaps, lithium composite soaps and aluminum composite soaps can be used alone or in combination as a thickener. Naturally, the urea compound may be a compound having both a urea bond and a urethane bond in addition to a compound having a urea bond.

  As is apparent from the examples in Table 1 and the comparative examples in Tables 2 to 9, the grease composition obtained by adding the additive (A) to the grease composition containing sodium thiosulfate is an excellent electrode. It has pressure resistance and rust prevention performance is greatly improved. In addition, a grease composition in which the additive (A) and the benzotriazole compound (B) are added to a grease composition containing sodium thiosulfate has excellent extreme pressure resistance and rust resistance, as well as excellent abrasion resistance. Has wear. Particularly in urea grease, lithium soap grease and lithium composite soap grease, the improvement in wear resistance is remarkable. In addition, since sodium thiosulfate has been recognized as a food additive for a long time and is also known as a universal antidote, it is an additive that is friendly to the human body and thus friendly to the global environment. Therefore, the present invention is a grease composition that is extremely excellent in environmental compatibility.

  As the base oil used in the present invention, synthetic oils such as vegetable oils, mineral oils and ester oils, ether oils, hydrocarbon oils or mixed oils thereof can be used.

The sodium thiosulfate used in the present _invention, Na ₂ S _{2 O 3 (anhydrous), Na 2 S 2 O 3} · 5H 2 O ( pentahydrate), or mixtures thereof. Commercially available additives including sodium thiosulfate (for example, Desirube 88, Desilube Technology, Inc. USA) can also be used.

  The present invention allows the sulfur in sodium thiosulfate to react with iron in the metal at high temperatures, and the layer formed by chemical bonding prevents the metal contact of the grease, and at the same time, by the synergistic effect of these additives, It is presumed that it strongly adsorbs to form a strong film and prevents rust generation and wear.

  The addition amount of the calcium sulfonate (A) and the benzotriazole compound (B) is 0.1 to 5% by weight, preferably 0.2 to 3% by weight, based on the total grease composition. is there. When the additive (A) is less than 0.1% by weight, the effect of inhibiting rust is insufficient, and when the additive (B) is less than 0.1% by weight, The effect of improving wear is insufficient. Further, even if these additives exceed 5% by weight, the effect is not further increased.

  Examples of the benzotriazole compound (B) include 1,2,3-benzotriazole, 2- (2'-hydroxy-5'-methylphenyl) -benzotriazole, 2- [2'-hydroxy-3 '-(3 ", 4", 5 ", 6" -tetrahydrophthalimidomethyl) -5'-methylphenyl] -benzotriazole, 2- (2'-hydroxy-3', 5'-di-t-butylphenyl) ) -Benzotriazole, 2- (2'-hydroxy-5'-t-octylphenyl) -benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-t-amylphenyl) -benzotriazole, 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2- (2′-hydroxy-3′-undecyl-5) And '-methylphenyl) -benzotriazole.

  In the present invention, amine-based and phenol-based antioxidants, extreme pressure additives such as sulfurized olefins and sulfurized fats and oils, extreme pressure / antiwear agents such as phosphites and phosphates, polybudenes and polymethacrylates are added. Viscous agents, solid lubricants such as molybdenum disulfide and boron nitride, or other various additives can be blended.

  Hereinafter, the present invention will be described with reference to examples and comparative examples, but the present invention is not limited thereto.

  According to the formulations shown in Tables 1 to 9, the additives corresponding to the above (A) and (B) or other additives are added to the base grease and treated with a three-roll mill to obtain greases of Examples and Comparative Examples. It was. The composition of the base grease is as shown below.

I. Urea-based grease produced by reacting diphenylmethane-4,4′-diisocyanate (295.2 g) and octylamine (304.8 g) in refined mineral oil (5400 g) having a kinematic viscosity at 100 ° C. of about 15 mm ² / s A urea-based grease having a consistency (25 ° C., 60 W) 289 and a dropping point of 263 ° C. was obtained by uniformly dispersing the urea-based compound. The content of the urea compound is 10% by weight.

II. Lithium soap-based grease In a refined mineral oil (5400 g) having a kinematic viscosity at 100 ° C. of about 15 mm ² / s, 12-hydroxystearic acid lithium (600 g) is dissolved and uniformly dispersed to obtain a consistency (25 ° C., 60W) 268, a lithium soap base grease having properties of a dropping point of 199 ° C. was obtained. The content of lithium soap is 10% by weight.

III. Lithium complex soap base grease 350 g of 12-hydroxystearic acid was reacted with 50.5 g of lithium hydroxide in refined mineral oil (4165 g) having a kinematic viscosity at 100 ° C. of about 11 mm ² / s, and then 120.65 g of azelaic acid was added. Lithium hydroxide was reacted with 59.0 g and uniformly dispersed to obtain a lithium composite soap-based grease having properties of a consistency (25 ° C., 60 W) 281 and a dropping point of 259 ° C. The content of the lithium composite soap is 10.4% by weight.

IV. Aluminum composite soap base grease 158.22 g of benzoic acid and 334.8 g of stearic acid are dissolved in refined mineral oil (4272 g) having a kinematic viscosity at 100 ° C. of about 11 mm ² / s, and then a commercially available cyclic aluminum oxide propylene lubricant. [Product name: Alkene manufactured by Kawaken Fine Chemical Co., Ltd.] is added to the reaction, and the resulting soap is uniformly dispersed and treated with an aluminum composite soap system having a consistency (25 ° C, 60W) 279 and a dropping point of 258 ° C. A base grease was obtained. The content of the aluminum composite soap was set to 11% by weight. The molar ratio of benzoic acid (BA) and stearic acid (FA) was BA / FA = 1.1, and the molar ratio of benzoic acid and aluminum (Al) to stearic acid was (BA + FA) /Al=1.9. .

  The resulting grease was subjected to a rust prevention test (wet test) and a four-ball test (EP test and wear resistance test) to confirm rust prevention, extreme pressure and wear resistance.

Wet test According to the wet test of JIS K2220 5.17, the sample was uniformly applied to the entire surface of the test piece so that the coating amount on one side was 0.30 ± 0.05 g. The steel plate coated with grease was hung in a wet box with a temperature of 49 ° C. and a relative humidity of 95% or more, and the degree of rust after 2 weeks was displayed in the grade of JIS K2246.
Grade Rust occurrence%
Class A 0
Class B 1-10
Class C 11-25
Class D 26-50
Class E 51-100

EP test According to ASTM D2596, the fusion load (N) was examined by a four-ball test.
Test condition Rotational speed 1770 ± 60rpm
Temperature 27 ± 8 ℃
Time 10 ± 0.2s

Wear Resistance Test According to ASTM D2266, the wear scar diameter (mm) of the ball was measured by a four ball test.
Test conditions Rotational speed 1200 ± 50rpm
Temperature 75 ± 1.7 ° C
Load 40 ± 0.2Kgf (392 ± 2N)
Time 60 ± 1 min

The test results are summarized in Tables 1 to 9.
Moreover, * 1, * 5- * 10 are as follows in a table | surface.
Desirube 88 * 1 is a product of Desilube Technology, Inc. This is an inorganic SP additive containing sodium thiosulfate.
NA-SUL729 * 5 is KING INDUSTRIES, INC. It is a product name of (A) and is equivalent to the calcium sulfonate.
BT-120 * 6 is a trade name of Johoku Chemical Co., Ltd., which is 1,2,3-benzotriazole and is equivalent to (B).

The following are additives other than the above (A) and (B).
NA-SUL ZS * 7 is KING INDUSTRIES, INC. It is the name of the product and it is the zinc sulphate.
Dailube Z-500 * 8 is a trade name of Dainippon Ink & Chemicals, Inc., which is zinc naphthenate.
NA-SUL SS * 9 is KING INDUSTRIES, INC. This is the product name of sodium sulfonate.
NA-SUL 707 * 10 is KING INDUSTRIES, INC. It is a trade name of lithium sulfonate.

Claims (3)

  A grease composition containing 0.05 to 30% by weight of sodium thiosulfate, wherein (A) calcium sulfonate is blended in an amount of 0.1 to 5% by weight based on the total composition.   Furthermore, the grease composition of Claim 1 which mix | blended (B) benzotriazole type compound 0.1 to 5weight% with respect to the whole composition.   The grease composition according to claim 1 or 2, wherein the thickener is at least one selected from a urea compound, lithium soap, lithium composite soap, and aluminum composite soap.