JPS6322896A - Lubricant comprising flowable perfluoropolyether having extremely high viscosity - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The object of the present invention is to obtain a
0, Q OOest preferably at least IQ, 00
The fluidized bar fluoropolyether with extremely high kinematic viscosity of 0 cSt is used as a lubricant and as a basic component of perfluorinated lubricating greases.

BACKGROUND OF THE INVENTION It is generally well known to use fluid, neutral-type di-fluoroboriethers as lubricating oils which have favorable properties with respect to resistance to airborne substances and chemicals, even at high temperatures.

Products suitable for use as 3q lubricants and currently available on the market are low- or medium-viscosity oils with maximum viscosity values of the order of 2,000 C8t at 20°C.

Surprisingly, perfluoropolyethers with high kinematic viscosity as described above exhibit surprisingly superior lubricating properties compared to the low-viscosity perfluoropolyethers that have been used so far. Do you get it.

Improvements in certain properties are not simply due to the higher viscosity of the compound, which should be considered unexpected.

DETAILED DESCRIPTION The fluoropolyethers of the present invention having viscosity values within the above specified ranges have the following units: -CF20F20-1
It is constituted by a mechanical chain of oxyperfluoroalkylene units selected from -CF20-, -CF2CF2CF20-1.

The end groups of the chain are of the perfluorinated, neutral type.

In particular, compounds belonging to the following groups are suitable.

(1) R'fO(CF20F2O)m(CF20)
nRf (where Rf and R'f are the same or different from each other and can be either -CF or -C2F, and the perfluorooxyalkylene units are randomly distributed along the chain) , and m% n is an integer such that the viscosity (which is a function of the average molecule) is within the indicated range. Jin's compound is covered by U.S. Patent No. 46
65.041 and the product name” Fo
mblin Z(R)w” is known in the market.

(2) R'f O(CF2 CF20) Rf
(and \, Rf and R'f are the same or different, and can be either -CF3 or -C,F,
and p is an integer such that the viscosity falls within the range indicated above). This maple compound is made in the United States 11+; No. 4.52
No. 3.059.

(5) R'fO(CF20F2CF2O)IsRf
(Here, Rf and R'f are the same or each other, and -CF3 or -C2Fm or -03F
, and 8 is an integer such that the viscosity falls within the range indicated above) Compounds of this type are disclosed in European Patent No. 148,482.

Considering the extremely high viscosity of these compounds and their extremely low volatility, and that their viscosity varies only to a small extent with variations in temperature due to their linear structure, the compounds of the present invention Can be beneficially used as a lubricant against high temperatures.

friction coefficient μ) IJ Beck number ηN/P (here,
It is known that there are relationships that make it possible to express it as a function of η - kinematic viscosity, N - rotational speed, P - applied load per surface unit. Due to the relationship reported in the diadem, the yarn is lubricated under boundary lubrication and the elastic fluid τ
It can be demonstrated that region V2 results in a mixed state of E slip. Regarding this, D. Claman (1)
"Lubricant" by , l(lamann)
s” (V@rlag Ch@mla 1984
), please refer to page 38 and below.

The perfluoropolyethers according to the invention show surprising and unexpected improvements such as in terms of wear rate under mixed oil-sliding conditions compared to conventional perfluoropolyethers having a much lower viscosity. is simply the viscosity difference sr
It cannot be explained by considering This can be thought to be related to the molecular structure of the compound for some reason.

The apparatus used to measure the wear rate is a carbon with an average surface roughness of 15 microns and a diameter of 45 mm.
15) Essentially constituted by a bottle-on-rig thread consisting of pins of the same material resting on the cylindrical surface of a specimen of material with a surface area of 12 mm and rotating at a speed of 550 rpm. The bins are loaded with 15 to 9 weights.

The procedure used in this test was as follows.

1.1.2-) Lichlor-2,2,
Purify in 1-trifluoroethane, dry and f
ill (h is measured. The test specimen is installed in the apparatus in such a way that it can be immersed inside the tray containing the lubricating oil. After 1000 revolutions, the test specimen is removed from the apparatus and t 'L2-) Lichloro-2,2.1-) Clean in lifluoroethane, dry, reweigh and then reincorporate into the apparatus.

After 10.000 rpm, repeat the measurement. Then,
Calculate the weight difference by comparing it to the number of experimental meters (ΔW/
L).

3 αlX10-5 5X10-5 5jxj
o-s ”30 1x10-5 2x10-
5 2.5x10-5Z1600: This is (1)
A perfluoropolyether belonging to the group of 20
°Fomb 1 i, a commercial product manufactured by Monte Edison, having a kinematic viscosity of 16.000c3t(1) at °C.
n ”0 μm: Same as above, but 250 μm
Z03 with a viscosity of 50 cst: similar to above but with a viscosity of 50 cst. There is. In particular, the time required to obtain wear is much longer for the highest viscosity oils.

The perfluoropolyethers of the present invention are particularly suited for the formulation of perfluorinated greases with improved properties compared to similar products made from low viscosity perfluoropolyether oils. The extremely low values of high temperature oil separation observed (even at much higher oil percentages in the grease than in prior art products) result in a new grease arc that is particularly suitable for high temperature applications.

The highly significant properties of the novel grease maple formulated with J-fluoropolyether compositions of the present invention are low static! !
(measured as starting resistance torque).

The method for producing the grease according to the invention is similar to the method as reported in European patent application EP 95,825, except that, due to the high viscosity of perfluoropolyether, the kneading and subsequent homogenization are carried out under high temperature conditions. The only difference is that it must be carried out below (70°C).

The amount of oil used in the formulation of polytetfluoroethylene (PTFE) 4M grease varies within the range of 60-90%.

The oil used is FomblIn z 1600 (product mentioned above) with a kinematic viscosity of 1 to 000 eat at 20°C.

It is introduced at a percentage of 74.1i relative to the grease.

The thickener is granular PTFE (average particle size 4-5 μm; molecular weight 40,000) used in a percentage of 25.9% by weight based on the grease.

Kneading and homogenization methods are described in the above-mentioned patent applications.

For comparison purposes, the same PTFE persimmons and 250est
F'omb 11 n (Jil) Z25 with a viscosity of
Perfluorinated grease by using oil'k Wl
I did.

The formulation is 6a, 5-fold fi 1% FomblIn@)Z
25 and XtS heavy % PTF'E.

(ASTM D217) 283
286 (person STM D217)
270 29B oil separation, 204℃
/30h (FTMS 791-321) 16%
It is evident that oil separation and evaporation are extremely low compared to 10% prior art perfluorinated greases.

Tribo-rheological properties of formulated greasesDetermination of their rheological properties by determining the kinematic viscosity of the grease by using a plate/cone system attached to a Rotovisco HAAKH12 thread with an M150 head (PKn/α3°) was carried out.

A first measurement was carried out at 25° C. by increasing the r (flow gradient) value to 20.40.80 sec''1) and measuring the viscosity of the grease at the start and after 15 minutes.

For each measurement, use fresh grease! It was changed.

In the inventive grease formulated with FomblIn ■ Z1600 i- an early transition period is observed and the period increases with decreasing t (5-6 minutes within the selected t range). During this period, the grease exhibits rheovectic behavior and stabilization of its manifestation at an equilibrium value higher than the initial value. Under these conditions, the variation in its symptoms is less than that of two greases with lower viscosity. The kinematic viscosity of the studied grease at 80 ha/c-1 is about 1100 voids, whereas Fombll
That of a grease formulated with nZ25 oil is approximately 260 voices under the same conditions.

Therefore, the behavior of the viscosity over time at a constant t-value shows that the grease according to the invention does not offer any higher resistance than under equilibrium conditions at start-up. This result, which is important in connection with the power that must be applied during startup, never occurred with low viscosity PFPE-based oil-based greases.

The exaggerated range of symptom variation indicates reliable constancy of lubrication performance.

The second measurement was carried out under constant conditions for 40 sec' at a temperature of 25°C, 50@C1100°C.

The durability of 11i1 lubricating grease at 100°C was exceptionally good, whereas low viscosity oil (Fombli)
Greases formulated under nz25) show a tendency to non-homogenization under the same conditions.

ASTM
Lubricity evaluation was performed by measuring the bath load according to the D2596 standard.

The welding load is as high as %700KP (the limit of island measurement).

Procedural amendment (method) % formula % Indication of case 1985 Patent application No. 109057 Person making the amendment

Claims (4)

[Claims] (1) The following oxyperfluoroalkylene unit, -CF
_2CF_2O-, -CF_2O-, -CF_2CF_
2CF_2O-, and has a linear structure composed of one or more repeats of
A lubricating oil consisting of a neutral perfluoropolyether having a kinematic viscosity within the range of 40,000 cSt. (2) The lubricating oil according to claim 1, having a kinematic viscosity of at least 10,000 cSt. (3) Perfluoropolyether has the structural formula R'_fO
(CF_2CF_2O)_m(CF_2O)_nR_f
[wherein R_f and R'_f are the same or different from each other and are either -CF_3 or -C_2F_5, the perfluorooxyalkylene units are randomly distributed along the chain, and m, n is an integer such that the viscosity of the perfluoropolyether falls within the indicated range. (4) A perfluorinated lubricating grease based on polytetrafluoroethylene and the perfluoropolyether lubricating oil according to claim 1, and containing 60 to 90% by weight of oil.