JPH0820789A - Biodegradable grease composition - Google Patents

Abstract

PURPOSE:To obtain a grease composition which has excellent biodegradability in the natural environment and retains long-lasting lubricity and oxidative stability both sufficient for practical use. CONSTITUTION:A biodegradable grease composition comprising a base oil comprising at least 80wt.% ester of pentaerythritol with an 8-12C linear fatty acid, a thickener, a sulfur/phosphorus compound extreme-pressure additive, and an antioxidant.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a grease composition having excellent biodegradability. More specifically, the present invention relates to a grease composition excellent in biodegradability which is decomposed in a short time even when it is released into a natural environment, and has no or little possibility of causing pollution of the ocean, rivers, groundwater, soil and the like.

[0002]

[Prior art and its problems] Grease is widely used for lubrication and rust prevention of various machines and devices such as automobiles, railway vehicles and rails, agricultural machinery, construction and construction equipment, and water treatment-related equipment. . These greases are often used in places where they may be released into the natural environment. However,
Many of these greases use mineral oil as the base oil which is the main component. However, mineral oil has poor biodegradability, and when released into the natural environment, it causes water quality and soil pollution. As means for solving such a problem, JP-A-5-86389 and JP-A-6-
In 1989, a biodegradable grease composition using a polyol ester oil or a vegetable oil as a base oil is disclosed. However, although the biodegradable grease compositions proposed hitherto certainly have improved biodegradability, they have a problem of insufficient lubrication life and oxidation stability.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a grease composition excellent in biodegradability which is decomposed in a short time even when it is released into a natural environment and has no or little risk of causing water pollution or soil pollution. It is to provide a grease composition having a practical lubricating life and oxidative stability.

[0004]

The objects of the present invention are achieved by a grease composition containing a specific base oil, a thickener, a specific extreme pressure agent and an antioxidant. That is, the present invention
Base oil containing at least 80% by weight of a linear fatty acid ester of pentaerythritol having 2n carbon atoms (n is an integer of 4 to 6); thickener; sulfur-phosphorus extreme pressure agent; and biodegradation containing antioxidant A grease composition is provided.

The present invention will be described in more detail below. The base oil used in the present invention is pentaerythritol having 2 carbon atoms.
It is a linear fatty acid ester of n (n is an integer of 4 to 6).
Examples of such straight chain fatty acid esters include caprylic acid, capric acid, adipic acid and mixtures of two or more thereof. In the present invention, the base oil contains at least 80% by weight of this particular pentaerythritol ester.
It is necessary to contain the above, preferably 90% by weight or more, and most preferably 100% by weight. If the proportion of the specific pentaerythritol ester in the base oil is less than 80% by weight, biodegradability is lowered, which is not preferable. In the grease composition of the present invention, the amount of base oil is appropriately 65 to 95.5% by weight. The thickener used in the present invention is not particularly limited, and those used in ordinary grease compositions can be used. For example, metal soap, urea, organized bentonite, silica and the like can be mentioned. As a metal soap,
Lithium 12-hydroxystearate, lithium complex, aliphatic diurea, alicyclic diurea and aromatic diurea as urea, montmorillonite treated with quaternary ammonium salt as organic bentonite, and vapor phase reaction as silica The ultrafine silica powder thus obtained or those obtained by treating the surface thereof with a lower alcohol such as methanol can be mentioned. In the grease composition of the present invention, the amount of the thickener is appropriately 3 to 20% by weight.

The extreme pressure agent used in the present invention is a sulfur-phosphorus type compound, which is a compound containing sulfur and phosphorus in the molecule,
Examples of commercially available products include Angramol 99 manufactured by Lubrizol Japan. Extreme pressure agents other than the sulfur-phosphorus system, for example, those containing heavy metals such as zinc, are not preferable because the biodegradability is significantly reduced. In the grease composition of the present invention, the amount of the extreme pressure agent is 1 to 10% by weight, preferably 2 to 7.5% by weight. Examples of the antioxidant used in the present invention include phenol compounds and aromatic amine compounds. Specific examples include 3- (N-salicyloyl) amino-1,2,4-2-triazole and dioctyldiphenylamine. The amount of this antioxidant in the grease composition of the present invention is preferably 0.5 to 5% by weight. The grease composition of the present invention can be produced by a conventionally known method. The biodegradability of the grease composition can be measured by the Chemical Substances Control Law or CEC-L-33-T-82, but the biodegradability of the grease composition of the present invention by CEC-L-33-T-82 is , Preferably 85% or more, more preferably 9
It is 5% or more, and most preferably 100%.

[0007]

The biodegradable grease composition of the present invention is highly biodegradable and has a practical lubricating life and oxidative stability.

[0008]

Examples 1 and 2 and Comparative Examples 5 to 7 (Lithium Complex Grease) 9.28% by weight of castor-cured fatty acid was dissolved in about 50% by weight of base oil to obtain equimolar amounts of castor-cured fatty acid and azelaic acid added later. After adding half the excess amount of the aqueous solution of lithium hydroxide and stirring, and then adding 2.93% by weight of azelaic acid and stirring until a uniform state was obtained, the rest of the aqueous solution of lithium hydroxide was added and stirred vigorously. . After confirming the completion of the saponification reaction by infrared spectroscopy, the mixture was heated to 210 to 220 ° C., the remaining base oil was added with stirring, and the mixture was cooled. Add antioxidant at 8 ° C below 120 ° C
An extreme pressure agent was added at 0 ° C. or lower, and the mixture was stirred and cooled to room temperature, followed by milling with a three-stage roll and defoaming treatment to prepare a grease composition.

[Example 3 and Comparative Examples 1 to 4] (Lithium grease) 9% by weight of castor-cured fatty acid was dissolved in about 50% by weight of base oil,
Lithium hydroxide in excess of equimolar to castor-cured fatty acid
After adding an aqueous solution of monohydrate and stirring, and heating to 210 ° C. for dehydration, the remaining base oil is added with stirring, and then the total amount of the antioxidant and extreme pressure agent is added, and the mixture is allowed to reach room temperature with stirring. After cooling, milling was performed with a three-stage roll and defoaming treatment was performed to prepare a grease composition.

Example 4 (Urea grease) About 40% by weight of base oil,
The mixture was heated to about 80 ° C., 5.89 wt% of diphenylmethane 4,4-diisocyanate was added, and the mixture was stirred and dissolved. On the other hand, about 40% by weight of base oil and 6.11% by weight of octylamine were placed in another container and heated to about 80 ° C., which was mixed with the above-mentioned diphenylmethane 4,4-diisocyanate / base oil and stirred vigorously. . After confirming that absorption of unreacted isocyanate (2200 cm ^-1 ) was not observed by infrared spectroscopy, the mixture was heated to 170 to 180 ° C while stirring. Stop heating, cool with stirring, add antioxidant at 120 ° C or less, extreme pressure agent at 80 ° C or less, and stir to cool to room temperature, then mill with a three-stage roll to defoam. To prepare a grease composition.

[0009] The penetration of this grease composition (JIS K
2220 5.3) (Index of grease hardness, smaller is harder), dropping point (℃), high speed 4 balls (ASTM D 2596) (Kgf) (extreme pressure performance test), bearing life (ASTM D 1741) ( 125 ℃) (hour), oxidation stability (JIS K 22205.8) (99 ℃: 100 hours) (kPa) (smaller is more stable) and biodegradability (Chemical Substances Control Law, CEC-L-33-T) -82) (larger is more degradable). The composition of the grease composition and the test results are shown in Table 1.

[0010]

[Table 1] Components Example Comparative Example  1 2 3 4 1 2 3 4 5 6 7 Base oil (1) 81.79 84.29 85.00 84.50 90.0 ─ ─ ─ 87.79 ─ 84.29 (2) ─ ─ ─ ─ ─ 90.00 ─ ─ ─ 81.79 ─ (3) ─ ─ ─ ─ ─ ─ 90.00 ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ 90.00 ─ ─ ─Thickener (5) ─ ─ 9.00 ─ 9.00 9.00 9.00 9.00 ─ ─ ─ ─ (6) 12.21 12.21 ─ ─ ─ ─ ─ ─ 12.21 12.21 12.21 (7) ─ ─ ─ ─ ─ ─ ─ ─ ─Extreme pressure agent (8) 5.0 2.5 5.0 2.5 ─ ─ ─ ─ ─ 5.0 ─ (9) ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ 2.5 Antioxidant (10) 0.5 0.5 0.5 0.5 1.0 1.0 1.0 1.0 ─ 0.5 0.5 (11) 0.5 0.5 0.5 0.5 ─ ─ ─ ─ ─ ─ 0.5 0.5 Property (12) 288 298 280 298 309 284 308 322 265 267 280 (13) 260 <260 <194 260 <201 205 196 200 260 <260 <260 <(14) 500 315 500 315 126 126 126 126 126 620 315 (15 ) 4000 <3000 <2000 <3000 <─ ─ ─ ─ ─ 519 3000 <3000 <(16) 25 25 27 25 13 15 83 44 ─ ─ 25 (17) 85 90 94 85 98 35 87 90 ─ 43 35(18) 99 ─ ─ 87 ─ ─ ─ ─ ─ 36 ─

(1) Mixed fatty acid (caprylic acid, capric acid and adipic acid) ester of pentaerythritol (2) Mixed fatty acid (enanthic acid, caprylic acid, capric acid and isononanoic acid) ester of pentaerythritol and dipentaerythritol (3) ) Isomethyl stearic acid ester of trimethylolpropane (4) Mixed fatty acid (caprylic acid, capric acid and dimer acid) ester of trimethylolpropane (5) Lithium salt of castor-cured fatty acid (6) Lithium salt of castor-cured fatty acid + azelaic acid ( 7) Urea (8) Sulfur-Phosphorus (9) Zinc dithiophosphate (10) Dioctyldiphenylamine (11) 3- (N-salicyloyl) amino-1,2,4-2
− Triazole (12) Mixing consistency (13) Drop point (℃) (14) High speed 4-ball WP (Kgf) (15) Bearing life (125 ℃, h) (16) Oxidation stability (kPa) (99 ℃, 100h) (17) Biodegradability (Chemical Substances Control Law) (18) Biodegradability (CEC-L-33-T-82)

The following can be seen from Table 1. The present invention containing a mixed fatty acid (caprylic acid, capric acid and adipic acid) ester of pentaerythritol as a base oil, a sulfur-phosphorus extreme pressure agent as an extreme pressure agent, and a thickener and an antioxidant. The biodegradable grease compositions of Examples 1 to 4 have a long bearing life, high oxidative stability, and high biodegradability. In contrast, Comparative Example 1 containing no extreme pressure agent has high biodegradability but low extreme pressure property. Comparative Example 2 using pentaerythritol and dipentaerythritol mixed fatty acid (enanthic acid, caprylic acid, capric acid and isononanoic acid) esters as a base oil and containing no extreme pressure agent
, The oxidative stability is high, but the biodegradability is low. In Comparative Example 3 which uses an isostearic acid ester of trimethylolpropane as a base oil and contains no extreme pressure agent, the biodegradability is high, but the oxidative stability is low.

In Comparative Example 4 which uses a mixed fatty acid (caprylic acid, capric acid and dimer acid) ester of trimethylolpropane as a base oil and contains no extreme pressure agent, the biodegradability is high but the oxidative stability is low. . In Comparative Example 5, which uses a mixed fatty acid (caprylic acid, capric acid, and adipic acid) ester of pentaerythritol as the base oil and does not contain an extreme pressure agent and an antioxidant, the extreme pressure property is low and the bearing life is short. Comparative Example 6 using a mixed fatty acid (enanthate, caprylate, capric acid and isononanoate) of pentaerythritol and dipentaerythritol as a base oil and containing an extreme pressure agent has a high extreme pressure property and a long bearing life. , Low in biodegradability. Comparative Example 7 using pentaerythritol mixed fatty acid (caprylic acid, capric acid and adipic acid) ester as the base oil and zinc dithiophosphate as the extreme pressure agent has a long bearing life but low biodegradability.

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Claims (4)

[Claims] 1. The carbon number of pentaerythritol is 2n (n
Is an integer of 4 to 6) at least 8 linear fatty acid ester
Base oil containing 0% by weight; thickener; sulfur-phosphorus extreme pressure agent;
And a biodegradable grease composition containing an antioxidant. 2. The composition according to claim 1, wherein the linear fatty acid is selected from the group consisting of caprylic acid, capric acid, adipic acid and a mixture of two or more thereof. 3. The composition according to claim 1, wherein the composition has a biodegradability of 85% or more. 4. A base oil comprising 65 to 95.5% by weight, a thickener 3 to 20% by weight, an extreme pressure agent 1 to 10% by weight, and an antioxidant 0.5 to 5% by weight. Or the composition according to 3.