JP2009161706A - Grease composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grease composition which has various excellent properties such as rustproof properties, extreme pressure properties, water resistance and heat resistance and particularly, is excellent in flame retardancy. <P>SOLUTION: The grease composition is obtained by blending lithium soap, calcium complexed soap and calcium sulfonate at the least in lubricating base oil. The calcium sulfonate is blended by 8-48 wt.%. The grease composition has various excellent properties such as rustproof properties, extreme pressure properties, water resistance and heat resistance and particularly, and is excellent in flame retardancy. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a grease composition used for a sliding part of a mechanical device and a bearing that requires heat resistance, rust resistance, and load resistance in various industrial machines.

  In recent years, the demand for lubrication environment has been very strict in various facilities such as steel manufacturing facilities, and the grease composition for lubrication has various performances such as excellent rust prevention, extreme pressure, water resistance and heat resistance. Requested. In addition, when a mechanical device using lubricating grease is installed and operated in a high temperature environment, if the high temperature scale of the mechanical device or processed material is scattered on the grease leaked from the bearing of the mechanical device, the grease will be removed. It may ignite and cause a fire. For these reasons, there is a demand for a grease composition having excellent performance as described above and having excellent flame retardance that is difficult to ignite even when a high-temperature scale is mixed.

  Conventionally, grease compositions using potassium or calcium oxides, carbonates, bicarbonates, and sulfates as additives are known in order to add flame retardancy to grease compositions. The grease composition comprises a lubricating base oil, a thickener selected from lithium soap, calcium soap, sodium soap or mixtures thereof, and 1 to 7% by weight oxidation based on the grease composition. And a flame retardant additive of a mixture containing 1 to 7% by weight of a potassium compound based on a grease composition selected from calcium and potassium carbonate, potassium hydrogen carbonate and potassium sulfate (for example, patent literature) 1).

In addition, greases that are self-extinguishing after ignition are known. The self-extinguishing grease composition has a self-extinguishing property with a self-extinguishing time of 5 minutes or less in an ointment can combustion test, and the flash point of the liquid component of the grease composition is 270 ° C. or higher. The self-extinguishing grease composition described above is a lubricating grease composition having excellent flame retardancy that is difficult to ignite even when the accumulated lubricating grease composition is exposed to a high temperature or a high-temperature scale is scattered. It can be used for a scale-intensive lubrication system (see, for example, Patent Document 2).
Japanese Patent No. 2999953 JP 2004-67843 A

  However, with conventional grease compositions, in order to make the grease difficult to ignite, a powder additive such as potassium carbonate is added to the grease, so that plugging occurs in piping in the centralized lubrication system. There was a risk of losing. In addition, in sliding bearings, wear of parts was accelerated by the additive powder, which could shorten the equipment life. Also, even with lubricating grease that exhibits self-extinguishing properties, self-extinguishing properties are not sufficient, and ignition cannot be prevented. there were. Furthermore, the grease having some of the excellent performances as described above has a problem in flame retardancy when hot scales are scattered. That is, grease with excellent flame retardancy or self-extinguishing properties cannot satisfy various performances such as rust prevention, extreme pressure, water resistance, and heat resistance. The flame retardancy when hot scales are scattered cannot be satisfied.

  The object of the present invention is to solve the above-mentioned problems, and as a result of intensive studies on flame retardancy, flame retardancy is improved by blending at least lithium soap, calcium composite soap and calcium sulfonate with a lubricating base oil. And found that these materials are suitable compositions for solving the above-mentioned problems of the prior art, where lithium soap, calcium composite soap and calcium sulfonate are added to the lubricating base oil. By blending, it is to provide a grease composition having excellent performance such as rust prevention, extreme pressure, water resistance and heat resistance, and particularly excellent in flame retardancy.

This invention uses mineral oil, synthetic oil, or a mixture thereof as a base oil, and contains 8 to 48% by weight of a mixture of lithium soap and calcium composite soap, and calcium sulfonate represented by the following general formula The present invention relates to a grease composition.
(R-SO ₃ ) ₂ Ca · nCaCO ₃ ────── (1)
Where R: a hydrocarbon group having 6 to 28 carbon atoms, n: an integer of 6 to 50

  In this grease composition, the lithium soap and / or the calcium complex soap includes at least one selected from saturated or unsaturated fatty acids having 2 to 22 carbon atoms, derivatives thereof, and boric acid compounds; It is comprised from the reaction product with lithium or calcium hydroxide.

  Since the grease composition according to the present invention is configured as described above, it has not only excellent rust resistance, extreme pressure, water resistance and heat resistance, but also excellent flame retardancy, and therefore has a severe lubricating environment. It can be applied to applications, and even if a high-temperature substance, for example, a high-temperature scale, is scattered in the lubricating grease, it is difficult to ignite and the safety at the work site can be improved. Furthermore, this grease composition can be made into a property having excellent low-temperature performance and excellent flame retardancy by using a base oil having good low-temperature performance.

  The grease composition according to the present invention solves the above-mentioned problems of the prior art, has excellent rust prevention properties, extreme pressure properties, water resistance and heat resistance, and is excellent in flame retardancy. This grease composition contains at least lithium soap, calcium composite soap and calcium sulfonate in a lubricating base oil. Each component of the grease composition will be described below.

  The lithium soap in this grease composition is a saponification reaction product of a fatty acid and lithium hydroxide. The fatty acid used is composed of at least one selected from saturated or unsaturated fatty acids having 2 to 22 carbon atoms and derivatives thereof. For example, lithium stearate can be exemplified as a lithium soap that satisfies these requirements.

  The calcium composite soap in this grease composition is a saponification reaction product of two or more fatty acids and calcium hydroxide. The fatty acid to be used is composed of at least two selected from saturated or unsaturated fatty acids having 2 to 22 carbon atoms and derivatives thereof, or boric acid compounds. For example, as a calcium composite soap satisfying these, a composite soap of calcium stearate and calcium acetate can be exemplified.

The calcium sulfonate in this grease composition is obtained by treating neutral alkyl or calcium alkylbenzene sulfonate to give a high total base number (measurement method: JIS K2501) of 50 to 500 mg KOH / g. , Also called overbased calcium sulfonate. This is represented by the following general formula (1).
(R-SO ₃ ) ₂ Ca · nCaCO ₃ ────── (1)
However, R: a hydrocarbon group having 6 to 28 carbon atoms, n: an integer of 6 to 50 The calcium sulfonate in this grease composition contains calcium carbonate but has scaly crystals. Is desirable. The calcium sulfonate used in this grease composition is a mixture with a carrier oil. As the carrier oil, mineral oil, polyalphaolefin, or the like can be used.

The base oil in the grease composition, as the kinematic viscosity range of the base oil, is a 10~2000mm ² / s at 40 ° C., in particular, it is desirable that the 15~500mm ² / s at 40 ° C.. The synthetic oil used in this grease composition is at least one selected from mineral oil, synthetic hydrocarbon oil, ester oil, phenyl ether oil, glycol oil, silicone oil, and fluorine oil. As the base oil, an appropriate base oil suitable for the performance can be selected according to the required performance. For example, when the low temperature performance is also imparted to the product of the present invention, It is desirable to use refined mineral oil or synthetic hydrocarbons.

  Various additives such as known solid additives, antioxidants, oily agents, extreme pressure agents, rust preventives, surfactants and the like can be added to the grease composition. Additives can be added.

Hereinafter, the present invention will be described in detail with reference to Examples 1 to 7 and Comparative Examples 1 to 3.
The evaluation test methods in the processing examples, examples and comparative examples are as follows.
(1) Consistency test method According to JIS K2220 5.3.
(2) Dropping point test method According to JIS K2220 5.4.
(3) Salt spray test method According to JIS K2246 5.35 (35 ° C, 5% salt water, spray for 72 hours).
(4) High-speed four-ball load bearing capacity According to ASTM D 2596.
(5) 10% water-containing shell roll test According to ASTM D1831.
As a test sample, a mixture of 5 parts by weight of pure water and 45 parts by weight of test grease was used.
A shell roll test is performed at 80 ° C. for 24 hours.
(6) Ignition test method The flame retardancy evaluation method of the present invention is shown below.
15 g of the grease composition is put in a crucible having an inner diameter of 40 mm and a depth of 36 mm.
An iron cuboid 10 mm long, 15 mm wide and 10 mm high is preheated to 900 ° C. and placed in a crucible containing the grease composition. At this time, the presence or absence of ignition of the grease composition is confirmed.
(7) Low temperature torque test method According to JIS K2220 5.14.

The base oils, thickeners and additives used in Examples 1 to 8 and Comparative Example 4 are as follows.
Thickener A: lithium soap Thickener B: calcium complex soap calcium sulfonate A: Brookfield viscosity (# 6 spindle, 25 ° C,
10 rpm, ASTM D-2196) 110,000 mm ² / s,
Total base number 300mgKOH / g, containing scale-like calcium carbonate, using mineral oil as carrier oil Calcium sulfonate B: Brookfield viscosity (# 6 spindle, 25 ° C,
10 rpm, ASTM D-2196) 108,000 mm ² / s,
Total base number 270 mgKOH / g, containing flaky calcium carbonate, using poly α olefin as carrier oil Base oil A: Paraffinic mineral oil, kinematic viscosity at 40 ° C. 138 mm ² / s
Base oil B: Poly α-olefin: Kinematic viscosity at 40 ° C. 30 mm ² / s
Extreme pressure agent: Sulfur-based extreme pressure agent

In Comparative Examples 1 to 3, mineral oil was used as the base oil. The following commercially available grease was used.
Comparative Example 1: Commercial Lithium Grease Comparative Example 2: Commercial Calcium Complex Grease Comparative Example 3: Commercial Aluminum Complex Grease

  In Comparative Example 4, a grease composition was produced using the base oil, thickener and additives shown in Table 1 in the amounts shown in Table 1, and the physical properties thereof were evaluated. The results of Comparative Examples 1 to 4 are shown in Table 1.

  As can be seen from Table 1, in the ignition test, all of Comparative Examples 1 to 4 ignited. The dropping point was 242 ° C. in Comparative Example 3, and 190 ° C. or lower in the other cases. In the salt spray test, Comparative Example 1 and Comparative Example 3 were class C, and Comparative Example 2 and Comparative Example 4 were class E. In the fusion load of the high-speed four-ball load capacity, Comparative Example 3 was 2450 N, and others were 1960 N. In the 10% water-containing shell roll test, the consistency difference between before and after the test was +30 or more in any of the comparative examples.

  Only the comparative example 4 which used poly alpha olefin for the base oil performed the low temperature torque test, and the starting torque was 108 mN * m and the rotational torque was 62 mN * m.

Examples 1 to 4 are shown in Table 2. A grease composition was produced using the base oil, thickener and additives in the amounts shown in Table 2, and their physical properties were evaluated. The results of Examples 1 to 4 are shown in Table 2.
Examples 5 to 8 are shown in Table 3. A grease composition was produced using the base oil, thickener and additives in the amounts shown in Table 3, and the physical properties were evaluated. The results of Examples 5 to 8 are shown in Table 3.

  As can be seen from Tables 2 and 3, in the ignition test, all of Examples 1 to 8 did not ignite. The dropping point was 266 ° C. in Example 1, and 270 ° C. or higher in the other examples. In the salt spray test, all examples were class A. In the fusion load of the high-speed four-ball load bearing capacity, Example 1 was 3920N, Example 2 was 4900N, and the other examples were 4900N or more, showing high extreme pressure properties. In the 10% water-containing shell roll test, the consistency difference before and after the test was +5 to -11.

  Low temperature torque tests were conducted only in Examples 6 to 8 using poly-α-olefin as the base oil. In Examples 7 and 8 in which calcium sulfonate B using poly-α-olefin was used as the carrier oil, the starting torque was 117 to 108 mN · m, and the rotational torque was 77 mN · m.

  The grease composition according to the present invention is used in various industrial machines, automobiles, household electrical appliances, precision equipment, medical equipment, etc. that require properties such as rust prevention, extreme pressure, water resistance, heat resistance and flame resistance. It is preferable for use in the sliding portion.

Claims (2)

Mineral oil, synthetic oil, or a mixture thereof is used as a base oil, and a mixture of lithium soap and calcium composite soap and a calcium sulfonate represented by the following general formula is contained in an amount of 8 to 48% by weight. A grease composition.
(R-SO ₃ ) ₂ Ca · nCaCO ₃ ────── (1)
Where R: a hydrocarbon group having 6 to 28 carbon atoms, n: an integer of 6 to 50 The lithium soap and / or the calcium complex soap includes at least one selected from saturated or unsaturated fatty acids having 2 to 22 carbon atoms, derivatives thereof, and boric acid compounds, lithium hydroxide or calcium hydroxide, The grease composition according to claim 1, wherein the grease composition comprises: