JPS6327599A - Lubricant - Google Patents

Abstract

PURPOSE:To provide a coating-film type fluorine-based lubricant containing a novel compound having fluorine-containing oxyalkyl group, oxyalkylene group and polar group in a molecule as an essential component, having excellent sliding durability and capable of keeping the lubrication effect over a long period. CONSTITUTION:The objective lubricant contains, as an essential component, the compound of formula I [Rf is fluorine-containing polyoxy-alkyl; R is (phenyl- substituted) oxyalkylene; m is integer of >=1; X is polar group of formula II or -OR' (R' is H, 1-6C alkyl or alkyl-substituted phenyl; R'' is H, methyl or phenoxymethyl)]. EFFECT:Abrasion of a magnetic disk can be prevented over a long period by applying the lubricant to the surface of a magnetic layer of a magnetic recording medium such as magnetic disk.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a coating film type lubricant, and particularly to a fluorine-based lubricant having excellent sliding durability.

[Prior art]

Fluorine-based compounds containing perfluoroalkyl bond chains in their molecules are being considered for several uses as materials with excellent lubricity. In particular, magnetic recording and reproducing devices such as magnetic disk drives are subject to more severe conditions than ever before, in that even the slightest amount of wear can lead to serious defects.

No. 58-41431, etc.), all of these publicly known examples are disclosed in JP-A No. 50-126586 or 58-29.
As detailed in No. 147, it targets the group of compounds represented by the general formula below, and was proposed as a base treatment for homogeneous application of fluorinated lubricating oil or as a lubricating effect on its own. It is something.

CnFzll(OR), -X (in the formula, n = 4 to 13, R is an alkyl group having 2 to 3 carbon atoms,
m=0 to 50, or -○H as a polar group.

-COOH, -3○'aMe (Me is K or N' a
)',.

-8O2F, -Coo, NH4 or -3OaH) However, even if this fluorine-containing compound is actually applied to a magnetic disk, the durability of the magnetic disk may not be sufficient if the frequency of sliding between the disk and head increases. There are cases where it is not possible to say. This is because the fluorine-containing alkyl group of the above-mentioned compound has a relatively small number of carbon atoms, 4 to 13, and therefore does not have sufficient lubricity.

This is thought to be because the durability of the magnetic disk is not sufficiently improved.

On the other hand, perfluoropolyether carboxylic acid having a molecular skeleton of a fluorine-containing polyoxyalkyl group having about 21 to 65 carbon atoms and -COOH1 at the end is applied to the surface of the magnetic layer to improve the durability of the magnetic layer. A proposal has been made (Japanese Unexamined Patent Publication No. 85929/1983).

In this example, the fluorine-containing polyoxyalkyl group is long enough to provide excellent lubricity and considerably improved durability, but it cannot be said that the durability is sufficient under harsh sliding conditions. .

[Problem that the invention seeks to solve]

As described above, even if the lubricant has a sufficiently long fluorine-containing polyoxyalkyl group, sufficient durability cannot be obtained if the sliding conditions are severe. The reason for this is thought to be that when the sliding conditions are severe, the amount of lubricant consumed on the sliding surface increases.

Therefore, in order to solve this problem, it is necessary to minimize the consumption of lubricant on the sliding surfaces.

[Tips for solving problems]

The invention of ; was made in view of the problems of the prior art, and as a result of various studies, it was found that in order to reduce wear on the sliding surface and improve the lubricating effect, This is based on the fact that it has been found that compounds having both a fluorine-containing oxyalkyl group, an oxyalkylene group, and a polar group are preferable. That is, general formula % formula %) (wherein Rf is a fluorine-containing polyoxyalkyl group, R is an oxyalkylene group or a phenyl-substituted oxyalkylene group, m is an integer of 1 or more, or -0CRCOOR', -OR'■ R'' (where R' is hydrogen, an alkyl group having 1 to 6 carbon atoms, or an alkyl-substituted phenyl group, and R' is hydrogen, a methyl group, or a phenoxymethyl group). ) By using a new compound represented by as a lubricant,
There is little wear on the sliding surfaces, and the lubricating effect is maintained for a long time.
When used by adhering to the magnetic layer surface of a magnetic recording medium such as a magnetic disk, it is possible to prevent wear of the magnetic disk over a long period of time.

[Effect]

The compound represented by the above general formula is generally viscous and oily at room temperature and normal pressure, and has a long chain fluorine-containing polyoxyalkyl group and a fluorine-free oxyalkylene group bonded to each other, and further includes: It is based on a structure in which a polar group is bonded to the end of an oxyalkylene group that does not contain fluorine, and is characterized by being composed of three molecular chains with different properties. First, because it contains a fluorine-containing polyoxyalkyl group with a relatively large number of carbon atoms, it exhibits an excellent lubricating effect, and the polar group at the end of the molecule has sufficiently good adsorption to magnetic layers, etc. Furthermore, the fluorine-free oxyalkylene group has excellent affinity with the binder resin in the magnetic layer, so it is firmly captured within the magnetic layer.

It has the effect of preventing lubricating substances from detaching from the magnetic layer.
Specifically, a group of lubricants and agents according to the present invention that are practically suitable are compounds represented by the following formula.

CF a'CF'a CF8CFs "" (In the formula, n is an integer of 1 or more, 1m is an integer of 1 or more, or -〇G) (C○○R' or -〇R'R' (Here, R' is a polar group represented by hydrogen, an alkyl group having 1 to 6 carbon atoms, or an alkyl-substituted phenyl group, and R1 is hydrogen, a methyl group, or a phenoxymethyl group) [Examples 1 to 5] 500 mα three-lens flask Kreitx 157FS
(Grade L, DuPont perfluoroalkyl polyether carboxylic acid 1 molecular weight ゛2500) 50g (
After thorough deaeration and dehydration, 200 g of dehydrated trichlorotrifluoroethane and SOCQ 2
Add 200 mEl and 5 mfl of pyridine,
The reaction was stirred at 80°C for several days. After that, trichlorotrifluoroethane and unreacted SOCQ z were removed by vacuum distillation, and 100 g of dehydrated trichlorotrifluoroethane was obtained.
Add 1 g of triethaneolamine to create a solution [■].

On the other hand, 50 g of sufficiently dehydrated tetraethylene glycol (molecular weight: 194) or
70 g of polyethylene glycol (molecular weight: 600) or 50 g of tetraethylene glycol monomethyl ether (molecular weight 208) or 50 g of tetraethylene glycol monobutyl ether (molecular weight 250) or polyethylene glycol mono-p-nonylphenyl ether (molecular weight 425) and dehydration. A mixed solution with 80 g of trichlorotrifluoroethane was prepared, the temperature was raised to 50° C., and solution [11] was slowly added dropwise thereto while stirring thoroughly. After dropping, heat and stir for a working time.

After washing the reaction product with methanol and water, vacuum distillation
The lubricants of the present invention of Examples 1 to 5 shown in Table 1 were obtained.

[Examples 6-7] 20 g moles of the lubricant of Examples 1-2 were mixed with 300 g of trichlorotrifluoroethane, 60 g of chloroform, and 10 g of the lubricant of Examples 1-2.
Put it in cyclohexyl 18 crown column. after that,
Place 20g of potassium permanganate in an Erlenmeyer flask and continue stirring at room temperature for a working time.After the reaction is complete, rinse thoroughly with water.
Vacuum distillation was carried out to obtain lubricants of the present invention in Examples 6 and 7 shown in Table 1.

[Example 8] 50 g (0.04 mol) of perfluoroalkyl polyether carboxylic acid (molecular weight 1200) having the following structure from Nippon Mektron Co., Ltd. and 100 ml of trifluorotrichloroethane were placed in a 500 mm three-ring flask, and thoroughly degassed. After dehydration, 250 mΩ of 5OCQx and 8 m of pyridine
Add Q and react at 80°C with stirring for several hours.

Then, after removing unreacted 5OCnx by vacuum distillation, 100 g of dehydrated trichlorotrifluoroethane and 1 g of triethanolamine were added to prepare a solution [I[].

Meanwhile, a sufficiently dehydrated polymer of phenyl glycidyl ether (average molecular weight 918
), create a mixed solution with 50 g of dehydrated trichlorotrifluoroethane, and 50 g of chloroform, raise the temperature to 50"C, and slowly add solution [II] dropwise to this while stirring thoroughly. 1 After dropping, heat and stir for a working time.

- The reaction product was washed with methanol and water and then vacuum distilled to obtain the lubricant of the invention of Example 8 shown in Table 1.

[Example 9] 30 g mole of the lubricant of Example 8 was dissolved in a mixed solvent of 300 g of trichlorotrifluoroethane, 60 g of chloroform, and 10 g of cyclohexyl 18 crown 6,
Pour into a 00mff1 Erlenmeyer flask. Thereafter, 20 g of potassium permanganate was placed in an Erlenmeyer flask, and stirring was continued at room temperature for a working time.

After the reaction was completed, the lubricant of the present invention of Example 9 shown in Table 1 was obtained by thorough washing with water and vacuum distillation.

The lubricants obtained in Examples 1 to 9 are applied onto an uncured magnetic coating of phenol epoxy resin.

Thereafter, the magnetic coating film is thermally cured. The sliding durability of this magnetic layer was tested.

The sliding durability test was conducted using a 1-spherical sliding testing machine.

That is, by applying a load Log to the sapphire spherical slider,
The disk was rotated at a circumferential speed of 10 n/s and an ambient temperature of 25°C, and evaluated by the total number of rotations until the magnetic coating was damaged. Table 2 shows the results. As a comparative example, the surface was After creating a magnetic coating film on the cleaned aluminum plate, a fluorine-based lubricant, Talitex 14, a magnetic disk lubricant described in USP 3490946, is applied on the coating film.
3 A case in which AC (trade name of DuPont) was simply applied was used.

As is clear from Table 2, by containing the lubricant obtained in this invention in a magnetic disk, the total time until the coating film breaks is longer than that of a magnetic disk coated with a conventional lubricant (comparative example). The number of rotations increases.

Table 2 5S41, a general structural steel material, was used as the bearing material, and the sliding parts were ultrasonically cleaned with trichlorethylene. Thereafter, it is baked in air at 380° C. for 20 minutes. Next, the surface of the sliding portion is uniformly mirror-finished with sandpaper to create a bearing material (1).

54 g (0,5
0 mole) to 1000 g of N-methyl-2-pyrrolidone
After completely dissolving, 147g of 3.3',4゜4'-bisphenyltetracarboxylic dianhydride (0,5
0 mol) is added. Stir these mixtures thoroughly,
Create a polyamic acid solution shown in the formula below.

1 g of the compounds of Example 3 and Example 5 were added to this polyamic acid solution and stirred homogeneously to prepare a solution. The bearing material (1) is immersed in a well-stirred solution and then left in a clean atmosphere at 50'C for two hours.

Thereafter, heat curing is performed at 350°C for 30 minutes. Plastic coated bearings that do not contain the compounds of Example 3 and Example 5 of the present invention, and comparative examples that do not contain the compounds of Example 3 and Example 5. The performance of the plastic coated bearing is shown in Table 3.1 The present invention has a low coefficient of friction;
Moreover, even at a high temperature of 250°C, the limit PV, which is an index of the sliding performance of the bearing, was high and excellent.

〔Effect of the invention〕

Claims (1)

[Claims] 1. General formula Rf-CO-(R)_m-X {wherein Rf is a fluorine-containing polyoxyalkyl group, R is an oxyalkylene group or a phenyl-substituted oxyalkylene group, and m is 1 or more An integer of A lubricant containing as an essential component a compound represented by a polar group represented by a methyl group or phenoxymethyl. 2. In claim 1, R is an oxyalkylene group having 2 to 3 carbon atoms. , or a lubricant that is a phenyl-substituted oxyalkylene group.