JPS6357693A - Non-diffusive grease - Google Patents

Abstract

PURPOSE:To obtain the title grease suitable for use in a helicoid portion and an iris diaphragm portion of a camera. a bearing mechanism of timepieces, and a mechanism portion of an electronic appliance and causing no dispersion of an oil component, by adding a fluorinated surfactant to a grease. CONSTITUTION:A grease comprising a lubricating base oil (e.g., diethylhexyl sebacate) and a thickener (e.g., a triurea compd.) blended therewith is blended with 0.01wt% or more fluorinated surfactant having a completely fluorinated fluorocarbon chain, such as a fluoroalkyl(2-10C)carboxylic acid, a perfluoroalkyl(4-12C)sulfonate, and a monoperfluoroalkyl(6-16C)ethyl phosphate.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a non-diffusible grease in which oil in the grease does not diffuse (lead).

[Conventional technology]

With the rapid improvement in performance and miniaturization of precision equipment in recent years, the grease used in mechanical rotating and sliding parts is now required to have better properties (quality) than before. It has started to be done. In other words, in many cases, grease used for various miniaturized mechanical parts, motors, various bearings, switches, contacts, etc.
Heat resistance, low temperature resistance, light torque, etc. are required. Therefore, in order to obtain the above characteristics, low viscosity synthetic oil is generally used as the lubricating base oil of grease.

[Problems to be solved by the invention]

However, when using low-viscosity synthetic oil, the performance described above can be almost satisfied, but in most cases, after applying the grease, the oil content or oily additives in the grease component diffuses (leaches out) from the applied surface over time. ) will come. In other words, since grease is a semi-solid with a solid thickener mixed and dispersed in a liquid lubricating base oil, over a long period of time these liquid lubricating base oils tend to separate from the grease and spread out as oil. . In particular, the lower the viscosity of the lubricating base oil, the more
Alternatively, the softer the consistency of the grease and the higher the temperature during use and storage, the more pronounced this tendency becomes. In many cases, this diffused oil contaminates equipment, causes contact failure, or flows to other parts and adversely affects the materials there (particularly plastics, etc.). Therefore, there has recently been a strong desire from various quarters to develop a grease with less oil diffusion.

[Means to solve the problem]

In view of such social demands, the inventors of the present invention have conducted intensive research to develop a non-diffusive grease with extremely low oil dispersion. Now, by incorporating a certain type of surfactant into the grease, we have developed a non-diffusive grease that can minimize oil diffusion in the grease. That is, the non-diffusible grease according to the present invention contains at least 0.01 wt% or more of a fluorine-based surfactant. Normally, surfactants increase the diffusion of oil by lowering the surface tension of liquid components, but in the case of the fluorine-based surfactant used in this invention, on the contrary, the diffusion of oil in grease is increased. It has the function of suppressing Among surfactants, this fluorine-based surfactant is the only one that has the ability to suppress the diffusion of oil from grease; when other general surfactants are included, oil tends to diffuse from grease. It is. Furthermore, even if a fluorine-containing oil (for example, trifluorochloroethylene, perfluoropolyether) is contained, the oil diffusion prevention function cannot be expected, and therefore a fluorine-containing surfactant is required. Here, fluorine-based surfactant is a general term for surfactants that do not have a hydrocarbon chain as a hydrophobic group, but have a completely fluorinated fluorocarbon chain (perfluorocarbon chain). . Specifically, *fluoroalkyl (C2-C
l0) Carboxylic acid, *Disodium N-perfluorooctanesulfonylglutamate, *Sodium 3-[fluoroalkyl (C, ~CI+)oxyf-1-alkyl (C1-C4) sulfonate* 3-[ω-fluoroalkanoyl ( 06~C,)-
Sodium N-ethylaminoco-1-propanesulfonate* N-(3-(perfluorooctanesulfonamido)propyl)-NSN-dimethyl-N-carboxymethyleneammonium betaine* Fluoroalkyl (C
r l-Cgo) carboxylic acid * Perfluoroalkyl carboxylic acid (C? ~ CI, ) * Perfluorooctane sulfonic acid jetanolamide * Perfluoroalkyl (C4-C1□) sulfonate (Li, Ni, Na) * N-Propyl-N-(2-hydroxyethyl) perfluorooctane sulfonamide* Perfluoroalkyl (C6-C3°) sulfonamidopropyl trimethylammonium salt solution Perfluoroalkyl (C4-C
1°) -N-ethylsulfonylglycine salt (K) *Bis(N-perfluorooctylsulfonyl-N-ethylaminoethyl) phosphate *Monoperfluoroalkyl (C6-CI&)ethyl phosphate, etc. At least 0.0% of the above fluorine-based surfactant is added to the grease. ◇1 wt% or more [preferably 0, 1 to 1
0wt% range]. If the content of the fluorosurfactant is less than 0.01 wt%, a significant oil diffusion prevention effect cannot be expected.
It is also possible to contain a large amount of fluorinated surfactants, but if it exceeds 15 wt%, the effect will reach an equilibrium and it will be economically disadvantageous. The agent may be a metal soap type, a composite surface soap type, a urea type, etc., and the lubricating base oil may be any type of grease such as mineral oil or various synthetic lubricating base oils.

[Example] A test was conducted regarding the oil diffusion prevention effect of the non-diffusible grease according to the present invention. First, the test method will be explained based on FIG. First, add grease 1 to 0.05 in a syringe.
Take each cc on a ground glass plate (IQcmX 10ao)
Apply it in a circular chevron shape to the rough side of 2, and place flat washers 3 with a thickness of 0.35 m on the four corners to provide clearance. Next, a ground glass plate 4 of the same type is stacked on top, with the rough surfaces facing each other, and pressure is applied so that the grease 1 forms a 15-frame circle. Then, it was placed in a constant temperature bath (80°C) and left for 24 hours, and the diffusion width (w) of the diffusion portion 5 where the rough surface of the ground glass plate 2.4 became translucent due to diffusion (oozing) of the oil was determined. The diffusion rate (%) was determined from the diffusion width. Incidentally, the diffusion rate is calculated as follows. Diffusion rate (χ) - ((diffusion width - 15) ÷ 15) X100
The test results are shown in the table below. In the table above, *Grease type A is a type of grease containing 5.0 wt% of a thickener [lithium hydroxystearate] in a lubricating base oil [poly alpha olefin (viscosity: 6 cst at 100°C)], which has a high consistency. The perfect score for Seed 1 is grease at 203°C. *What is grease type B? 8W of thickener [triurea compound] is added to lubricating base oil [diethylhexyl sebacate].
This is a grease with a consistency of 0.1% and a dropping point of 260°C. *What is fluorine thread surfactant type X? It is a fluorinated alkyl ester. *What is fluorine thread surfactant type Y? It is a fluoroalkyl (C8°) carboxylic acid. As can be seen from the examples shown in the table above, in the grease containing a fluorosurfactant, the diffusion of oil was extremely small, and even if there was some, it was negligible. On the other hand, in the greases of the comparative examples that do not contain any fluorosurfactant, significant diffusion of oil content was clearly confirmed. [Effects] Therefore, the non-diffusive grease according to the present invention has Applications in the field of precision equipment, such as helicoid parts of cameras, aperture mechanisms, bearing mechanisms of watches, rotating shafts of micromotors, etc.
Suitable for use in various bearings, mechanical parts of electronic devices, switches, etc. Further, the characteristics of the fluorosurfactant itself (chemical resistance, heat resistance) are also favorable as an additive for grease. Furthermore, when this fluorine-based surfactant is contained in a polyurea-based grease represented by grease type B, it is possible to combine the polyurea-based thickener and synthetic hydrocarbon (or high viscosity, high viscosity index mineral oil).
Ancillary effects were also confirmed, such as improved compatibility with the grease and the ability to improve the quality of the grease itself.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing an oil diffusion test method used in an example of the present invention. 1 ・−・ Grease 2.4 ・−・ Ground glass plate 3 ・−・ Flat washer 5 ・−・ Diffusion part

Claims (1)

[Claims] A non-diffusible grease characterized by containing at least 0.01 wt% or more of a fluorine-based surfactant.