JP3345129B2 - Grease composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a grease composition having improved lubricity.

[0002]

2. Description of the Related Art A sliding part and a rotating part of a machine need some kind of lubricating base material, but most of them use lubricating oil or grease. In particular, the sealing structure can be simplified, and the apparatus can be made compact and compact. Many machines adopt the grease lubrication system that can be used for a long time. For example, the range of use is extremely wide, including various types of rolling bearings and slide bearings that support rotating bodies, ball joints, links or chains, gears, wires, and sliding parts of crane booms. Life and maintenance-free are common issues for all machines. In recent years, with the advance of mechanical technology, material technology and processing accuracy, fatigue fracture of materials has become extremely small, and the life of the machine is greatly affected by the performance of grease. Therefore, it is extremely important to improve the lubricity of grease to solve these problems because it can greatly contribute to the improvement of the quality and reliability of the machine.

[0003] Here, there are roughly two cases in which the lubricating performance of grease is reduced in a rotating part or a sliding part of a machine, and the machine life is exhausted.
First, when used at high temperatures, grease is oxidized and solidified by evaporation of oil or thermal polymerization, or the grease structure is destroyed due to generation of organic acids or aldehydes. When used at low speed and high load, the sliding surface tends to be in a boundary lubrication state, and the grease lubricating film becomes very thin, so metal contact frequently occurs, abrasion increases, and damage such as metal peeling and seizure occurs. In some cases.

Means for solving the first case include a method in which an appropriate antioxidant is effectively mixed into the grease, and a method in which a thickener or a base oil having excellent oxidation stability is used as a grease raw material. Means for solving the second case include a method of increasing the base oil viscosity of the grease and increasing the thickness of the lubricating oil film to suppress metal contact, and adding a load-bearing additive such as an anti-wear agent or an extreme pressure agent to the grease. In this method, a coating is formed between sliding surfaces by chemical or physical adsorption of additive molecules to protect the surface.

[0005] By the way, load-bearing additives used in a system for improving the wear resistance and load-bearing properties of grease by utilizing the load-bearing additives are extremely limited. The reason is that grease is a structured lubricant, and its structure is composed of three thickener molecules.
Dimensionally arranged and balanced to maintain a stable grease state, but many load-bearing additives break the grease structure, causing softening and dropping of the grease, and free grease remaining in the grease. It reacts with chemical substances and causes a change over time. For example, when chlorinated paraffin or the like is added to lithium grease, the consistency softens greatly and when subjected to long-time shearing, it becomes fluid and the drop point drops. Further, the phosphate ester reacts with lithium hydroxide as a free alkali in the lithium grease to generate lithium phosphate, and when water is mixed, hydrolysis occurs to make the grease structure unstable. In addition, thiophosphates having a high acid value have a disadvantage that they easily react with the free alkali of soap-based grease. Furthermore, sulfurized olefins cause some urea greases to harden over time, and also reduce the corrosiveness to copper and the strength of nitrile and acrylic rubbers. Among these load-bearing additives, those which change the grease structure or have a relatively small adverse effect on metals, rubbers and the like are solid lubricants. Examples of the solid lubricant include molybdenum disulfide, graphite, PTFE (polytetrafluoroethylene), tungsten disulfide, graphite fluoride, boron nitride, and the like. However, since molybdenum disulfide and graphite are black, their use is extremely limited in terms of plant contamination during the production of grease, work environment at the grease destination, and product contamination. PTFE, tungsten disulfide, graphite fluoride, and boron nitride are white or gray and have almost no pollution problems. Can be

JP-A-54-73804 discloses that a lubricating oil has the following formula (II)

There is disclosed a heat-resistant grease to which potassium tetrafluoromica represented by KMg _2.5 Si ₄ O ₁₀ F ₂ ... (II) is added as a thickener. However,
Obviously, this potassium tetrafluoric mica is not used as a lubricity improver, and the amount used is a large amount, such as the same amount as the base oil.

Further, Japanese Patent Publication No. 60-50235 discloses grease obtained by combining a synthetic inorganic layered structure of sodium tetrasilicic mica as a basic particle with a specific quaternary ammonium salt acting thereon. Although the technology to be added to is disclosed, these particles are also used as a thickener for grease,
Referring to the examples, the amount of use is such that 40 kg is added to 253 liters of the base oil, which is a considerably large amount.

[0008]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to improve the lubricating performance of grease by using an additive which is relatively inexpensive, is stable to grease, and has low contamination.

[0009]

SUMMARY OF THE INVENTION The present invention provides

Embedded image A ₂ [Mg ₅ (Si ₈ O ₂₀ ) F ₄ ] (I) (where A is K or Na) is used as a lubricity improver A grease composition characterized in that the grease composition contains 1 to 10% by weight.

[0010] The grease used as the base material includes all greases used as lubricating greases, and is not particularly limited. Examples of greases that can be used include lithium grease, calcium grease, sodium grease, barium grease, calcium complex grease, aluminum complex grease, lithium complex grease, bent grease, clay grease, urea grease, and Na-grease.
There is terephthalamate grease and the like.

Further, the addition amount of fluorine tetrasilicic mica to the grease is effective when it is 1 to 10% by weight, preferably 2 to 7% by weight. If the amount is less than 1% by weight, the effect is not improved, and if it is more than 10% by weight, the hardness of the grease is increased, and the lubricating performance is rather lowered and the cost is increased.
Fluorine tetrasilicic mica is a synthetic mica using talc as a main raw material, and can be synthesized by dissolving an appropriate raw material under atmospheric pressure or by a solid phase reaction.

[0012] The particle size suitable as an additive of the fluorine tetrasilicic mica varies depending on the surface roughness and the load of the lubricating portion, but is preferably 100 µm or less, and if it is larger than 100 µm, the appearance of the grease may be rough or the sliding surface may be damaged. Does not work smoothly.

Further, fluorotetrasilicon silicon mica acts as a promoter of wear and oxidation as natural mica Fe ₂ O ₃ and Al
_Since it hardly contains ₂ O ₃ , it has no adverse effect on the deterioration of the lubricating surface or grease. Fluorine tetrasilicic mica is a substance having a layered structure such as that found in MoS ₂ and graphite. It is composed of extremely thin cleaved pieces and exhibits low surface cleavage and high flexibility and elasticity. It is thought that it has a function of suppressing contact between surfaces.

In the method for producing the grease composition of the present invention, a fluorine-silicone mica is added to a grease base material and sufficiently kneaded.
Specifically, in the grease production process, in the cooling process after the reaction of the grease base material, fluorine tetrasilicic mica is added and sufficiently kneaded, and a normal treatment is performed using a homogenizer or a roll, or What is necessary is just to add fluorine tetrasilicic mica to the grease thus obtained and knead it sufficiently at room temperature or at a temperature of about 80 ° C.

The grease composition of the present invention may contain, if necessary, various antioxidants such as phenols and amines, rust inhibitors such as carboxylate, sulfonate and oxidized wax, higher fatty acids, and glycerin. Oil agents such as higher alcohols and esters, sulfurized fats and oils, thiophosphates, anti-wear agents such as alkyl phosphates, alkyl phosphates, and organic molybdenum, and extreme pressure agents can be blended.

[0016]

The present invention will be specifically described below with reference to examples.

Example 1 490 g of a general lithium grease base material obtained by a saponification reaction between a fatty acid and lithium hydroxide and a type II fluorine tetrasilicon mica [mica in which A in the general formula (I) is Na] And an average particle size of 1 to 5 μm] was heated to 80 ° C. while stirring in a grease-producing kettle. 1
The heating and stirring were continued for 0 minutes, and then the grease was taken out of the kettle, and the grease was uniformly finished with three rolls.
The resulting grease has a consistency of 323 and a dropping point of 187.
° C. As is clear from Tables 1 and 3, the grease of this example is compared with the grease of the comparative example in that the shell globules Ep
The final non-seizure load and load abrasion index in the test are improved,
Further, the width of the wear mark in the LFW wear test was small, and a remarkable effect was observed.

Comparative Examples 1 to 7 Tables 3 and 4 were prepared according to the production methods of the examples corresponding to the respective numbers.
Grease was prepared according to the recipe shown in Table 4.

Example 2 485 g of a general lithium grease base material obtained by a saponification reaction of a fatty acid and lithium hydroxide and a type I fluorine tetrasilicon mica [mica of the general formula (I) wherein A is K And an average particle diameter of 5 to 10 μm] was heated in a grease-producing kettle with stirring, and grease was obtained in the same manner as in Example 1 below. The resulting grease had a consistency of 321 and a dropping point of 189 ° C. As is clear from Tables 1 and 3, the grease of this example has improved final non-seizure load and load abrasion index in the shell four-ball Ep test as compared with Comparative Example 1, and has a small wear scar width in the LFW abrasion test. , A remarkable effect was observed.

Example 3 475 g of the same lithium grease base material as in Examples 1 and 2 and 25 g of type II tetrasilicon mica were obtained according to the methods of Examples 1 and 2. The grease consistency obtained was 327 and the dropping point was 188 ° C. As is clear from Tables 1 and 3, the grease of this example has improved final non-seizure load and load abrasion index in the shell four-ball Ep test as compared with Comparative Example 1, and the wear marks of the block in the LFW abrasion test. The width is extremely small, and the effect of improving load resistance and wear resistance is recognized.

Example 4 495 g of a general diurea grease base material easily obtained by a chemical reaction between 2 mol of a primary monoamine and 1 mol of a diisocyanate, and 5 g of a type I fluorine tetrasilicic mica
Was heated to 80 ° C. while stirring in a grease production kettle. After heating and stirring for 10 minutes, the grease was taken out of the kettle, and the grease was uniformly finished with three rolls. The resulting grease has a consistency of 326 and a dropping point of 26.
8 ° C. As is clear from Tables 2 and 3, the grease of this example has improved final non-seizure load and load abrasion index in the shell four-ball Ep test as compared with Comparative Example 2,
The width of the wear mark in the FW wear test is small, and a remarkable effect is recognized.

Example 5 A grease was obtained according to the method of Example 4 from 485 g of a diurea grease base material similar to that of Example 4 and 15 g of type I tetrasilicon mica. The consistency of the obtained grease is 3
At 33, the dropping point was 269 ° C. The grease of this example exhibited the same effect as the grease of Example 4 (see Table 2).

Examples 6 to 7 The greases shown in Examples 6 to 7 were obtained in the same manner as described above, but any of the greases was compared with Comparative Examples 1 to 4 in terms of the fusion load, the final non-seizing load, and the shell four-ball Ep test. It can be seen that the load abrasion index was improved, and the wear scar width of the block in the LFW abrasion test was extremely small, and the load resistance and wear resistance were significantly improved (see Table 2).

Further, Comparative Examples 5 and 6 are greases containing molybdenum disulfide and are substantially equivalent in performance to the grease of the example, however, since the color of the grease is gray-black, there is a problem of plant contamination during grease production. Also, there are problems such as contamination of the working environment or product contamination at the place of use, and the use is restricted (see Table 4). Comparative Example 7 is a lithium grease mixed with a load-bearing additive. Although the performance was excellent in the shell four-ball Ep test, the grease became fluid and the shear stability was poor in the shell roll test (see Table 4). ).

[0025]

[Table 1]

[0026]

[Table 2]

[0027]

[Table 3]

[0028]

[Table 4]

* 1: The composition of type I is represented by A of the general formula (I)
Is a mica composed of K (potassium) having an average particle size of 5 to 10 μm. * 2: The composition of type II is a mica in which A in general formula (I) is composed of Na (sodium) and has an average particle size of 1 to 5 μm. * 3: The LFW abrasion test was performed under the following conditions using an alpha model LFW-1 tester specified in ASTM D2741. The outline of the test machine is shown in FIG. (Conditions) Test ring: Steel (SAE 4620) Test block: Copper alloy (ALBC2) Grease sponge: Polyurethane (40 mm long x 40 m wide)
g × 16 mm) Grease amount: 5.0 g applied to sponge Load: 1 lb Rotation speed: 1800 rpm Time: 10 min Test temperature: room temperature Measurement: Measure the wear width of the test block after the test

[0030]

[Effect] The grease composition of the present invention has an effect on load resistance and abrasion resistance particularly in lubricated parts under severe load conditions, for example, lubricated parts such as roller bearings for steel rolling mills and journal bearings for forging presses. Therefore, it can greatly contribute to extending the life of the machine, reducing the amount of lubrication, or achieving maintenance-free operation.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a wear tester used in an example.

[Explanation of symbols]

 1 test block 2 test ring 3 sponge 4 wire (for fixing)

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-54-73804 (JP, A) JP-A-55-5902 (JP, A) JP-A-5-112786 (JP, A) JP-A-6-112 145685 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C10M 125/30 C10N 10:02-10:04 C10N 30:06 C10N 50:10

Claims (1)

(57) [Claims] 1. The following general formula (I): A ₂ [Mg ₅ (Si ₈ O ₂₀ ) F ₄ ] (I) (where A is K or Na) A grease composition comprising 1 to 10% by weight of the indicated fluorine tetrasilicic mica as a lubricity improver.