JP3130427B2 - Grease composition for fittings - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a grease for a joint used for a gear joint, a universal joint and the like which are industrially used.

[0002]

2. Description of the Related Art Many gear joints and universal joints are used in factories and the like, but cannot be replenished except for lubrication and lubrication during periodic inspections. °, universal joint: maximum inclination angle of 9 °), and at the same time, a sliding motion between the lubricating surfaces occurs, so that the lubricating material used is required to have high extreme pressure and lubricity.

In recent years, for the purpose of rationalization in factories and the like, it has been desired to extend the lubrication and lubrication intervals. However, even if grease having the above-described performance is filled, the inside of a gear joint or a universal joint is filled. Since the grease gradually leaks, frequent accidents occur in which the lubricated surface is worn or broken, which is a major problem. It is considered that grease leakage causing this damage is promoted by separation of the grease thickener and the base oil. Therefore, the base oil is not supplied from the grease to the lubrication surface, and the lubrication effect is lost. On the other hand, the separated thickener accumulates on the tooth surface, which hinders smooth rotation of the gear and causes vibration. (Research on Machinery, Vol. 35, No. 11, (1983) 69).

[0004] Therefore, high-performance joint greases for gear joints and universal joints have been demanded. Such a grease is required to have a performance in which it is difficult for grease to leak from a gap of a seal due to centrifugal force or to separate a thickener from a base oil, and extreme pressure resistance and wear resistance at a gear oil level. Further, there is also a demand for a property of good workability for maintenance and inspection such that grease leakage and gear damage can be easily recognized.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a long-life grease for a joint which has little leakage of grease and has good lubricity.

[0006]

That is, according to the present invention, a low molecular weight polyethylene having a number average molecular weight of 1,000 to 4,000 is added to a base grease comprising a base oil and a thickener.
It is a grease composition for joints, in which 1 to 5 parts by weight is blended with respect to 100 parts by weight of base oil.

The base oils used in the present invention include poly-α-olefins, synthetic hydrocarbon base oils such as polybutene synthetic squalane, polyol ester base oils such as dibasic acid diester and neopentyl polyol ester, and alkyl phosphate esters. Base oils such as glycerol, allyl phosphate ester, polyglycol base oils such as polyethylene glycol, polypropylene glycol, polyethylene glycol ester, polyethylene glycol ether, naphthenic mineral oil, paraffin mineral oil, aromatic mineral oil, highly refined One or a mixture of two or more base oils such as mineral oil base oils such as mineral oils can be used. However, synthetic hydrocarbon base oils are inexpensive because of their high temperature properties and high affinity with low molecular weight polyethylene. , Mineral base oils and other hydrocarbon base oils or Base oils as a component is preferable.

The thickener used in the present invention is a substance which is dispersed in a base oil and has a role of exhibiting a micellar structure and exhibiting a semi-solid state, and includes sodium soap, lithium soap, calcium soap, calcium complex and the like. Soaps such as soap, aluminum complex soap, lithium complex soap, and non-soaps such as Benton, silica airgel, sodium terephthalamate, urea, polytetrafluoroethylene, and boron nitride can be given. Among these, urea-based ones are preferred because they have excellent separation resistance even under high temperature and high centrifugal force, and triurea-based thickeners such as triazine triurea are particularly preferred.

A base grease can be obtained by blending the above base oil and thickener in a known ratio. In the present invention, the base grease has a number average molecular weight of 1,000 to
A low molecular weight polyethylene having a molecular weight of 4,000, preferably 1,200 to 2,500 is blended. As such a polyethylene, a low acid number type or an acid-modified low molecular weight polyethylene is preferable. For example, high wax 220M manufactured by Mitsui Petrochemical Industry Co., Ltd.
P, 1105A and the like. In addition, this compounding quantity is base oil 1
It is 1 to 5 parts by weight with respect to 00 parts by weight.

Further, together with low molecular weight polyethylene, polyisobutylene, polyalkyl methacrylate, polyalkyl acrylate, polyvinyl acetate, ethylene-
Polymers such as propylene copolymers and hydrogenated styrene-diene copolymers may be added.

Further, in addition to the base grease and the low molecular weight polyethylene, various additives such as extreme pressure additives, antiwear agents, antioxidants and rust preventives, which are usually blended, are added to the grease composition of the present invention. Can be blended. Here, suitable wear inhibitors include boron compounds and the like, and extreme pressure additives include sulfur compounds, phosphorus compounds, organometallic compounds and the like, and boron compounds and zinc dialkyldithiophosphate, Mo It is preferable to use extreme pressure additives such as -dialkyldithiocarbamate and sulfur-phosphorus extreme pressure additives in combination.

Examples of the boron compound include borates such as potassium borate, tribenzyl borate, organomercaptoalkyl borates (US Pat. No. 3,303,130), reaction products of tribenzyl borate and ethylene glycol (US Pat. No. 3,400,833), and borate esters. And an addition compound of phosphate sulfoxide. Among them, borate such as potassium borate is preferable, and the compounding amount thereof is 100 base oil.
The range of 5 to 10 parts by weight relative to parts by weight is good.

The zinc dialkyldithiophosphate as the extreme pressure additive is (RO) ₂ PS ₂ -Zn-PS ₂ (OR)
₂ (where R is an alkyl group)
The compounding amount is preferably in the range of 0.1 to 1 part by weight based on 100 parts by weight of the base oil.

Further, Mo-dialkyldithiocarbamate
Is (R_TwoNCS_Two)_TwoMo_TwoO _xS_y(However, R is
Alkyl group), the amount of which is
0.1 to 1 part by weight per 100 parts by weight of oil is better.
No.

Sulfur-phosphorus extreme pressure additives include sulfur additives such as sulfurized fats and oils, sulfurized terpenes, sulfurized olefins, and sulfides, and phosphorus-based additives such as phosphites, phosphates, and amine salts of phosphates. Pressurizing agent, and the amount used is 0.01 to 100 parts by weight of the base oil.
5 parts by weight, preferably in the range of 0.1 to 2 parts by weight.
In the present invention, the zinc dialkyldithiophosphate does not become a sulfur-phosphorus extreme pressure additive even if it contains phosphorus and sulfur.

On the other hand, the grease composition of the present invention may contain, in addition to the above components, additives which are usually added, such as an antioxidant and a rust inhibitor, if necessary. As antioxidants, 2,6-di-t-butylparacresol, 4,
Phenols such as 4 ′ methylenebis (2,6-di-t-butylphenol) and 4,4′methylenebis (6-t-butyl-o-cresol), p, p′-dioctyldiphenylamine, phenyl-α-naphthylamine , Aromatic amine chain terminating antioxidants such as phenothiazine, sulfurized fats and oils, benzyl sulfide, sulfur such as diacetyl sulfide, and zinc dialkyldithiophosphate,
Sulfur, such as zinc diallyldithiophosphate, and phosphorus-based peroxide-degrading antioxidants, and metal inactive, such as N, N 'disalicylidene-1,2-diaminopropane, benzotriazole, and 2 (n-dodecyldithio) benzimidazole. One type or a mixture of two or more types of each antioxidant of the type antioxidant can be used.

Examples of the rust preventive include sulfonates such as barium naphthalene sulfonate, amines such as N-alkyl trimethylene diamine dioleate, aliphatic amine-naphthenic acid condensate, various naphthenates, oleyl sarcosine. One or two or more kinds of mixtures such as amino acid derivatives such as, for example, sodium nitrite and benzotriazoles can be appropriately compounded.

The grease composition of the present invention is suitable as a grease for centralized lubrication of, for example, the above-mentioned gear joint and universal joint, and can also be used for bearing grease, wheel bearing grease, chassis grease and the like.

Generally, molybdenum disulfide, graphite, and the like are used to improve the extreme pressure property and wear resistance of grease.
A technique of adding a solid lubricant such as antimony sulfide is widely used. However, although the extreme pressure properties and wear resistance of the grease are improved, the grease is colored black,
There is a problem in that it is difficult to confirm the state of the gears, and it causes dirt. Therefore, without using this, by replacing the above-mentioned boron compound, while imparting the same extreme pressure resistance and wear resistance as when a solid lubricant is added, the color of the grease to a non-black system, for example, a yellow system Since it can be changed, the above problem is solved, and in addition to the prevention of dirt, the workability is improved.

[0020]

EXAMPLES Examples and comparative examples of the present invention are shown below. Using the base oils shown in Table 1, grease compositions for joints shown in Table 2 were obtained. For the greases of Examples 1 to 9 and the grease of the comparative example, a gear joint tester (condition: declination of the shaft center at both ends of the joint 3 °, rotation speed 1200 min ⁻¹ , torque 20 kg ·
m, time 1 hr), the grease performance was evaluated by measuring the amount of scattering and abrasion. The splash test measured how much grease scattered from the joint, in which the diameter of the oil seal was reduced and scattering due to rotation was more likely to occur. The wear test measured the weight change of the inner cylinder of the gear joint before and after the test. Grease was sealed in one gear joint at 38 ± 0.5 g. As a comparative example, a test using a commercially available lithium mineral soap extreme pressure grease (polyisobutylene-containing type) was performed.

[0021]

[Table 1]

[0022]

[Table 2]

The amount of scatter in Table 2 is considered to be a measure of grease leakage under high centrifugal force. The embodiment using the grease of the present invention is extremely suitable as a grease for a joint because the amount of scatter is extremely small. You can see that there is. From the amount of inner cylinder wear shown in Table 2, the example using the grease of the present invention hardly causes abrasion due to fretting or the like, which is a problem with grease, can extend the machine life, and is extremely excellent as grease for joints. You can see that. Further, when a boron compound is used, there is an effect that the color of the grease does not become black as in the case of using graphite or the like.

[0024]

The grease composition for joints of the present invention can reduce the amount of grease scattered even under a high centrifugal force and can reduce the amount of wear. When the grease composition for a joint of the present invention is used for a gear joint, a universal joint, or the like, the thickener and the base oil are hardly separated, the grease is less leaky, and the abrasion hardly occurs. Life is also improved.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshiaki Yoa 5-3 Tokai-cho, Tokai City, Aichi Prefecture, Nagoya Works, Nippon Steel Corporation (72) Inventor Katsumi Nagano 4-chome of Tsutsujigaoka, Chita City, Aichi Prefecture 12 (72) Inventor Masuhiro Onoyama 1-111-14 Koyo, Chigusa-ku, Nagoya-shi, Aichi (72) Inventor Kazuo Kato 1-34-22, Sakashita, Itabashi-ku, Tokyo, Chuo Yuka Co., Ltd. (72) Inventor Mori Hiroshi 1-34-22 Sakashita, Itabashi-ku, Tokyo, Chuo Yuka Co., Ltd. (56) References JP-A-60-31598 (JP, A) JP-A-6-41569 (JP, A) JP-A-2- 194095 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) C10M 143/02 C10N 50:10 WPI (DIALOG)

Claims (2)

(57) [Claims] A low-molecular weight polyethylene having a number average molecular weight of 1,000 to 4,000 is blended in a base grease comprising a base oil and a thickener in an amount of 1 to 5 parts by weight based on 100 parts by weight of the base oil. A grease composition for joints, characterized by comprising: 2. The base grease further comprises a boron compound and one selected from the group consisting of zinc dialkyldithiophosphate, molybdenum dithiocarbamate and sulfur-phosphorus extreme pressure additives.
The non-black type joint grease composition according to claim 1, wherein one or more extreme pressure additives are blended.