JP6244933B2 - Lubricant composition - Google Patents

Description

  The present invention relates to a lubricant composition, and more particularly to a lubricant composition suitable as a grease that can reduce the amount of corrosive gas released into the environment and reduce the release into the environment.

  Fluorine-based lubricants are widely used to lubricate various machines such as automobiles, electrical equipment, construction machines, information equipment, industrial machines, machine tools, and parts constituting them.

  In recent years, with the miniaturization, high performance, high density, and light weight of machine parts, the environmental temperature at which the lubricant is used tends to increase.

  Even under high-temperature environments, it is required that the load on the environment, such as harmful chemical substances, noise, and energy consumption, be small, and ensuring safety from the standpoint of consumers and business operators is being considered.

  In particular, the vicinity of a heat source such as a heater is likely to become high temperature compared to other places, and even if it is overheated even in a short time, efforts to reduce harmful gases released from peripheral members even when exposed to high temperatures are required. .

  Perfluoropolyether oil has low volatility and is excellent in thermal stability, oxidation stability, radiation resistance, chemical resistance, solvent resistance, etc., so it can be used as a lubricating oil or grease base oil in high-temperature environments. It is used.

  Even in a perfluoropolyether oil used at a high temperature, the perfluoropolyether oil gradually begins to decompose and generate corrosive gas in an environment exceeding 400 ° C.

  To solve these problems, the stability of perfluoropolyether oil is usually improved by using additives such as fluorinated alcohols and fluorinated diamide compounds in order to suppress the decomposition of perfluoropolyether oil. I am letting.

  While these techniques can certainly improve the stability of perfluoropolyether oils, they are no longer able to meet the increasing demands in recent years.

  Patent Document 1 discloses a compound having a pyridine ring, which shows good performance in the stability of a perfluoropolyether base. However, it is suggested that the production method for obtaining a fluorine-containing alcohol corresponding to a phase transfer catalyst and a pyridine derivative usually requires esterification of the corresponding acid fluoride and a reduction reaction, and is multi-step (Patent Document) 2).

  Similarly, Patent Document 3 discloses a fluorinated diamide compound for the purpose of stabilizing perfluoropolyether oil. Although it can certainly contribute to the improvement of stability, the fact is that it has become unable to satisfy the increasing market demand in recent years.

  Against this background, there is a high demand for reducing the amount of corrosive gas released into the environment and reducing the release into the environment, among growing market demands.

JP 2004-346318 A U.S. Pat. No. 3,810,874 JP 2009-185099 A

  Then, the subject of this invention is providing the lubricant composition which can reduce the quantity of the corrosive gas discharge | released in an environment, and can reduce the discharge | release to an environment.

  The other subject of this invention becomes clear by the following description.

  The above problems are solved by the following inventions.

1.
A lubricant composition comprising a divalent metal compound having a specific surface area of 1.0 to 20.0 m ² / g and a perfluoropolyether oil and containing 5 % by weight or more and 10% by weight or less of the metal compound.

2.
^2. The lubricant composition according to 1, wherein the metal compound has a specific surface area of 1.0 to 11.0 m ² / g.

3.
3. The lubricant composition according to 1 or 2, wherein the metal compound is at least one selected from calcium oxide, calcium hydroxide, zinc oxide, or magnesium oxide.

4).
The perfluoropolyether _{oils, F (CF 2 CF 2 CF} 2 O) 2~100 CF lubricant composition according to any one of the 1 to 3 with 2 CF ₃ structure.

  According to the present invention, it is possible to provide a lubricant composition capable of reducing the amount of corrosive gas released into the environment and reducing the release into the environment.

Graph showing the relationship between calcium oxide specific surface area and fluorine (F) ion concentration Graph showing the relationship between calcium oxide content and fluorine (F) ion concentration A graph showing the relationship between the blending ratio of calcium oxide and the friction coefficient for 30 minutes

The lubricant composition of the present invention contains a divalent metal compound having a specific surface area of 1.0 to 20.0 m ² / g and a perfluoropolyether oil (base oil).

  The lubricant composition of the present invention may be used as a fluorine oil or as a grease. When used as a grease, a thickener is added.

  In the present invention, preferred is an embodiment used as a grease.

  Specific examples of the perfluoropolyether oil used in the present invention include those represented by the general formulas (I) to (IV).

Formula (I)
RfO [CF (CF ₃ ) CF ₂ O] _i Rf

  In formula, Rf represents a C1-C5 perfluoro low acid alkyl group, such as a perfluoromethyl group and a perfluoroethyl group. i is an integer of 2 to 200.

The perfluoropolyether oil represented by the general formula (I) is obtained by anodically polymerizing hexafluoropropylene by completely fluorinating a precursor produced by photo-oxidation polymerization of hexafluoropropylene or under a cesium fluoride catalyst. The obtained acid fluoride compound having a terminal CF (CF ₃ ) COF group is treated with fluorine gas.

Formula (II)
RfO [CF (CF ₃ ) CF ₂ O] _l (CF ₂ O) _m Rf

  In the above formula, Rf is the same as defined above, l + m = 3 to 200, and randomly bonded at l: m = 10: 90 to 90:10.

  The perfluoropolyether oil represented by the general formula (II) can be obtained by completely fluorinating a precursor produced by photo-oxidative polymerization of hexafluoropropene.

General formula (III)
RfO (CF ₂ CF ₂ O) _j (CF ₂ O) _k Rf

  In the above formula, Rf is the same as the above definition, j + k = 3 to 200, and j: k = 10: 90 to 90:10 are randomly combined.

  The perfluoropolyether oil represented by the general formula (III) can be obtained by completely fluorinating a precursor produced by photo-oxidative polymerization of tetrafluoroethylene.

Formula (IV)
F (CF ₂ CF ₂ CF ₂ O) _i CF ₂ CF ₃

In the formula, i is an integer of 2 to 200.
The perfluoropolyether oil represented by the general formula (IV) is obtained by anionic polymerization of 2,2,3,3-tetrafluorooxetane in the presence of a cesium fluoride catalyst, and the resulting fluorinated polyether (CF ₂ CF the ₂ CF _{2 O) n} obtained by the original fluorine gas treatment of ultraviolet irradiation under 160 to 300 ° C..

  In the present invention, a preferred perfluoropolyether oil has a structure of the general formula (I), (II) or (IV), and more preferably has a structure represented by the general formula (IV). is there.

  In addition, although the structure shown by the general formula (III) can be used, it is inferior in stability at high temperatures compared to the structures shown by the general formulas (I), (II) and (IV). Under the high temperature condition, the structure represented by the general formulas (I), (II) and (IV) is desirable. More preferably, the structure represented by the general formula (IV) is desirable.

  In the present invention, the perfluoropolyether base oil can be used alone or in combination.

When used as a grease, the kinematic viscosity (40 ° C.) is about 5 to 2000 mm ² / s, preferably about 100 to 1500 mm ² / s, and more preferably 150 to 500 mm ² / s. Here, the kinematic viscosity is measured according to JIS K-2283 (2000) (Canon-Fenske viscometer).

Those with less than 5 mm ² / s have a large evaporation amount and do not satisfy the condition of the evaporation amount (1.5% or less) stipulated in the JIS rolling bearing grease type 3 which is a rule for heat-resistant grease. On the other hand, the thing exceeding 2000 mm < ² > / s has a high pour point (JIS K-2283), and the bearing does not rotate at a low temperature start-up in a normal method, and it is necessary to heat to make it usable, As a general grease, use qualification is lacking.

  Examples of the divalent metal oxide that can be used in the present invention include calcium oxide, calcium hydroxide, zinc oxide, magnesium oxide, cadmium oxide, cadmium carbonate, copper oxide, silver oxide, nickel oxide, and cobalt oxide. .

  Among these metal oxides, at least one selected from calcium oxide, calcium hydroxide, zinc oxide or magnesium oxide can be preferably exemplified.

The specific surface area of the metal oxide (BET measurements) is in the range of 1.0~20.0m ² / g, more preferably at 1.0~17.0m ² / g, and more preferably 1.0 ˜11.0 m ² / g is used.

When the specific surface area (BET measurement) is less than 1.0 m ² / g, the particles are large, which causes the friction coefficient to be increased when the particles enter between the sliding portions. Moreover, when it exceeds 20.0 m < ² > / g, it becomes a cause which raises a friction coefficient similarly by aggregation of particle | grains.

Experiments by, 1.0~20.0m ² / g absorption of fluorine ion is higher in the range of, higher absorption of fluoride ion in the range of 1.0~17.0m ² / g, 1.0~ It has been found that the absorption of fluorine ions is particularly high in the range of 11.0 m ² / g.

  The aforementioned divalent metal compound is blended in a proportion of 3% by weight to 10% by weight and preferably added and mixed in a proportion of 5% by weight to 10% by weight with respect to the entire lubricant composition. When the addition exceeds 10% by weight, the improvement of HF gas reduction is not seen, but the tendency to deteriorate the friction coefficient is seen. On the other hand, when the addition ratio is less than 3% by weight, a sufficient HF gas reduction effect is not sufficiently expected.

  Thickeners that can be used in the present invention include fluorine resins such as polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropene copolymer (FEP), perfluoroalkylene resin, carbon fluoride, graphite. , Carbon, molybdenum disulfide, melamine cyanurate (MCA), synthetic mica, boron nitride (BN), and the like. Among them, a fluororesin is preferable, and PTFE is more preferably selected.

  Among these thickeners, in the case of a fluororesin, it can be synthesized by the following method, or can be synthesized by a known method, and other thickeners are also available from commercial products.

  For reference, a method for synthesizing PTFE among fluororesins will be shown. Polytetrafluoroethylene having a number average molecular weight Mn of about 1,000 to 1,000,000 is produced by methods such as emulsion polymerization, suspension polymerization, and solution polymerization of tetrafluoroethylene, and it is pyrolyzed and electronically PTFE having a number average molecular weight Mn of about 1,000 to 500,000 is obtained by treatment by a method such as beam irradiation decomposition or physical pulverization.

  In addition, the copolymerization reaction of tetrafluoroethylene and hexafluoropropene and the molecular weight reduction treatment in the production of FEP are performed in the same manner as in the case of polytetrafluoroethylene, and the number average molecular weight is about 1,000. The one having about 600,000 is used. The molecular weight can be controlled using a chain transfer agent during the copolymerization reaction.

  The obtained powdery fluororesin is generally about 500 μm or less, preferably fine particles having an average primary particle diameter of 0.01 to 50 μm, and more preferably an average primary particle diameter of 0.1 to 30 μm. In this specification, the average particle diameter in the “average primary particle diameter” is an arithmetic average of the primary particle diameters of particles (100 or more) observed with an electron microscope. The primary particle size is the particle size of a particle such as polytetrafluoroethylene in the form of the smallest non-aggregated unit, and means the maximum particle size that can be measured between two opposing points of the diameter of each particle.

  In the lubricant composition of the present invention, an antioxidant, a rust inhibitor, a corrosion inhibitor, an extreme pressure agent, an oily agent, and the like are further added as necessary as long as the object of the present invention is not impaired. be able to.

  Examples of the antioxidant include phenolic antioxidants such as 2,6-ditert-butyl-4-methylphenol and 4,4′-methylenebis (2,6-ditert-butylphenol), alkyldiphenylamine (alkyl). Group has 4 to 20 carbon atoms), triphenylamine, phenyl-α-naphthylamine, phenothiazine, alkylated-α-naphthylamine, phenothiazine, alkylated phenothiazine and the like.

  Examples of the rust preventive agent include fatty acids, fatty acid amines, alkylsulfonic acid metal salts, alkylsulfonic acid amine salts, oxidized paraffin, polyoxyalkyl ether, and the like.

  Examples of the corrosion inhibitor include benzotriazole, benzimidazole, thiadiazole and the like.

  Examples of extreme pressure agents include phosphorus compounds such as phosphate esters, phosphite esters and phosphate ester amine salts, sulfur compounds such as sulfides and disulfides, dialkyldithiophosphate metal salts, and dialkyldithiocarbamic acid metal salts. Can be mentioned.

  Examples of the oily agent include fatty acids or esters thereof, higher alcohols, polyhydric alcohols or esters thereof, aliphatic amines, and aliphatic monoglycerides.

Examples of the method for producing the lubricant composition (grease) in the present invention include the following methods. That is, a predetermined amount of a thickener (PTFE) and a divalent metal compound having a specific surface area of 1.0 to 20.0 m ² / g are mixed with perfluoropolyether, and the mixture is sufficiently kneaded with a three-roll or high-pressure homogenizer. Can be obtained.

Conventional fluorine grease uses fluorine oil as a base oil, fluorine resin as a thickener, and consists of a small amount of additives. In the present invention, by selecting a divalent metal compound having a specific surface area of 1.0 to 20.0 m ² / g as an additive, the problem relating to the reduction of HF gas generated from the fluorine-based lubricant can be solved. In particular, it has been found that selecting a divalent metal compound having a surface area in the range of 1.0 to 11.0 m ² / g is effective.

  Examples of the present invention will be described below, but the present invention is not limited to such examples.

1. Effect confirmation test to suppress generation of fluorine (F) ion concentration

Comparative Example 1
<Manufacture of lubricating grease composition>
Base oil having a structure of F (CF ₂ CF ₂ CF ₂ O) _2-100 CF ₂ CF _{3 represented by the} general formula (IV) (40 ° C. kinematic viscosity: 200 mm ² / s) (“DEMNUM S” manufactured by Daikin Industries, Ltd. -200 ") is blended with fluororesin PTFE powder having an average primary particle size of 0.1 to 0.3 [mu] m (" Lublon L-2 "manufactured by Daikin Industries, Ltd.) (thickener) in the amount shown in Table 1, and high pressure Thoroughly kneading with a homogenizer, a lubricating grease composition was obtained.

<Test method>
Using this lubricating grease composition as a sample, the sample was weighed in a sample boat and heated in a quartz tube heated to 460 ° C. for 5 minutes. The generated gas was absorbed in an absorbing solution (ultra pure water), and the fluorine (F) ion concentration was quantified by ion chromatography. The concentration was converted to the concentration with respect to the lubricating grease composition. The results are shown in Table 1.

Comparative Example 2
<Manufacture of lubricating grease composition>
Comparative Example 1 is the same as Comparative Example 1 except that the following additive 1 is added to the formulation shown in Comparative Example 1 and the amounts of base oil, thickener, and additive 1 are as shown in Table 1. Thus, a lubricating grease composition was obtained.

(Additive 1)
Calcium oxide (commercially available product) manufactured by Wako Pure Chemical Industries, Ltd. was pulverized to adjust the specific surface area (BET measurement) to 6.1 m ² / g.

<Test method>
Similarly to Comparative Example 1, the fluorine (F) ion concentration was quantified. The results are shown in Table 1.

Example 1
<Manufacture of lubricating grease composition>
A lubricating grease composition was obtained in the same manner as in Comparative Example 2, except that the blending amounts of the base oil, thickener and additive 1 were changed to the blending amounts shown in Table 1.

<Test method>
Similarly to Comparative Example 2, the fluorine (F) ion concentration was quantified. The results are shown in Table 1.

Example 2
<Manufacture of lubricating grease composition>
A lubricating grease composition was obtained in the same manner as in Example 1, except that the blending amounts of base oil, thickener and additive 1 were changed to the blending amounts shown in Table 1.

<Test method>
The fluorine (F) ion concentration was quantified in the same manner as in Example 1. The results are shown in Table 1.

Example 3
<Manufacture of lubricating grease composition>
A lubricating grease composition was obtained in the same manner as in Example 1, except that the blending amounts of base oil, thickener and additive 1 were changed to the blending amounts shown in Table 1.

<Test method>
The fluorine (F) ion concentration was quantified in the same manner as in Example 1. The results are shown in Table 1.

Example 4
<Manufacture of lubricating grease composition>
A lubricating grease composition was obtained in the same manner as in Example 2, except that Additive 1 was replaced with Additive 2 below.

(Additive 2)
Zinc oxide: “Zincox super F-1” manufactured by Hakusuitec, specific surface area (BET measurement) 10.0 m ² / g

<Test method>
The fluorine (F) ion concentration was quantified in the same manner as in Example 2. The results are shown in Table 1.

Example 5
<Manufacture of lubricating grease composition>
A lubricating grease composition was obtained in the same manner as in Example 2, except that Additive 1 was replaced with Additive 3 below.

(Additive 3)
Magnesium oxide: “Star Mag PSF” manufactured by Kamishima Chemical Industry Co., Ltd., specific surface area (BET measurement) 10.1 m ² / g

<Test method>
The fluorine (F) ion concentration was quantified in the same manner as in Example 2. The results are shown in Table 1.

Example 6
<Manufacture of lubricating grease composition>
A lubricating grease composition was obtained in the same manner as in Example 2, except that Additive 1 was replaced with Additive 4 below.

(Additive 4)
Calcium hydroxide: “NICC” manufactured by Inoue Lime Industry Co., Ltd., specific surface area (BET measurement) 10.2 m ² / g

<Test method>
The fluorine (F) ion concentration was quantified in the same manner as in Example 2. The results are shown in Table 1.

Example 7
<Manufacture of lubricating grease composition>
A lubricating grease composition was obtained in the same manner as in Example 2, except that Additive 1 was replaced with Additive 5 below.

(Additive 5)
Calcium oxide (commercially available product) manufactured by Wako Pure Chemical Industries, Ltd. was pulverized to adjust the specific surface area (BET measurement) to 0.3 m ² / g.

<Test method>
The fluorine (F) ion concentration was quantified in the same manner as in Example 2. The results are shown in Table 1.

Example 8
<Manufacture of lubricating grease composition>
A lubricating grease composition was obtained in the same manner as in Example 2, except that Additive 1 was replaced with Additive 6 below.

(Additive 6)
Calcium oxide (commercially available product) manufactured by Wako Pure Chemical Industries, Ltd. was pulverized to adjust the specific surface area (BET measurement) to 1.1 m ² / g.

<Test method>
The fluorine (F) ion concentration was quantified in the same manner as in Example 2. The results are shown in Table 1.

Example 9
<Manufacture of lubricating grease composition>
A lubricating grease composition was obtained in the same manner as in Example 2, except that Additive 1 was replaced with Additive 7 below.

(Additive 7)
Calcium oxide (commercially available product) manufactured by Wako Pure Chemical Industries, Ltd. was pulverized to prepare a specific surface area (BET measurement) of 10.3 m ² / g.

<Test method>
The fluorine (F) ion concentration was quantified in the same manner as in Example 2. The results are shown in Table 1.

Example 10
<Manufacture of lubricating grease composition>
A lubricating grease composition was obtained in the same manner as in Example 2, except that Additive 1 was replaced with Additive 8 below.

(Additive 8)
Calcium oxide (commercial product) manufactured by Wako Pure Chemical Industries, Ltd. was pulverized to prepare a specific surface area (BET measurement) of 17.0 m ² / g.

<Test method>
The fluorine (F) ion concentration was quantified in the same manner as in Example 2. The results are shown in Table 1.

Comparative Example 3
<Manufacture of lubricating grease composition>
A lubricating grease composition was obtained in the same manner as in Example 2, except that the additive 1 was replaced with the following additive 9.

(Additive 9)
Calcium oxide (commercial product) manufactured by Wako Pure Chemical Industries, Ltd. was pulverized to prepare a specific surface area (BET measurement) of 20.2 m ² / g.

<Test method>
The fluorine (F) ion concentration was quantified in the same manner as in Example 2. The results are shown in Table 1.

Comparative Example 4
<Manufacture of lubricating grease composition>
A lubricating grease composition was obtained in the same manner as in Example 2, except that Additive 1 was replaced with Additive 10 below.

(Additive 10)
Calcium oxide (commercial product) manufactured by Wako Pure Chemical Industries, Ltd. was pulverized to prepare a specific surface area (BET measurement) of 25.0 m ² / g.

<Test method>
The fluorine (F) ion concentration was quantified in the same manner as in Example 2. The results are shown in Table 1.

Example 11
<Manufacture of lubricating grease composition>
In Example 2, the base oil represented by the general formula (I) RfO [CF (CF ₃ ) CF ₂ O] _{2 to 100} Rf (where Rf is a perfluoromethyl group) structure (40 ° C. motion) (Viscosity: 400 mm ² / s) (“BARRIERTA J400 FLUID” manufactured by NOK Kluber Co., Ltd.) was similarly used to obtain a lubricating grease composition.

<Test method>
The fluorine (F) ion concentration was quantified in the same manner as in Example 2. The results are shown in Table 1.

2. Confirmation test of relationship between specific surface area of calcium oxide and fluorine (F) ion concentration Suppressing generation of fluorine (F) ion concentration when 5% by weight of calcium oxide is blended in the lubricant composition as a divalent metal compound Effect Confirmation Test Experiments in which 5% by weight of calcium oxide was added as an additive were carried out in Examples 2, 7 to 10, and Comparative Examples 3 and 4 (7 points).
A graph showing the relationship between the specific surface area of calcium oxide and the fluorine (F) ion concentration is shown in FIG.

3. Relation between calcium oxide blending ratio and fluorine (F) ion concentration Using a calcium oxide that is a divalent metal compound adjusted to a specific surface area of 6.1 m ² / g, the blending ratio of calcium oxide in the lubricant composition The effect of suppressing the generation of fluorine (F) ion concentration was confirmed.
Experiments in which calcium oxide having a specific surface area of 6.1 m ² / g was blended were carried out in Comparative Examples 1, 2, and Examples 1, 2, and 3 (5 points).
A graph showing the relationship between the calcium oxide content and the fluorine (F) ion concentration is shown in FIG.

4). Implementation of Friction Resistance / Abrasion Test The following Pin on Disk test was performed.
<Specimen>
Upper test piece: Cylinder φ10 × 10mm (PTFE)
Lower specimen: Plate (PI)
<Test conditions>
Temperature 130 ° C
Load 600gf
Speed 360mm / s
Test time 30 minutes

<Evaluation>
Lubrication using the test pieces of Comparative Example 2, Examples 1, 2, 3, and Comparative Example 5 below using calcium oxide, which is a divalent metal compound, adjusted to a specific surface area of 6.1 m ² / g The friction coefficient for 30 minutes was determined by changing the compounding ratio of calcium oxide in the agent composition, and the friction characteristics were examined. The results are shown in Table 2 and FIG.

Comparative Example 5
A lubricating grease composition was obtained in the same manner as in Comparative Example 2, except that the blending amounts of base oil, thickener and additive 2 were changed to the blending amounts shown in Table 2.

  The present invention can be applied to a component that relatively moves between two surfaces (reciprocating motion, swinging motion, unidirectional motion) in an environment where the temperature is high near the heater.

For example, linear guides such as baking machines, ovens, rolling bearings, copiers, fixing rolls such as laser beam printers, fixing belts, rolling bearings, sliding bearings, gear parts, rolling bearings in a continuous press in wood processing equipment, Used in plain bearings, pins, gears, etc.

Claims (4)

A lubricant composition comprising a divalent metal compound having a specific surface area of 1.0 to 20.0 m ² / g and a perfluoropolyether oil and containing 5 % by weight or more and 10% by weight or less of the metal compound. The lubricant composition according to claim 1, wherein the metal compound has a specific surface area of 1.0 to 11.0 m ² / g.   The lubricant composition according to claim 1 or 2, wherein the metal compound is at least one selected from calcium oxide, calcium hydroxide, zinc oxide, or magnesium oxide. The perfluoropolyether _{oils, F (CF 2 CF 2 CF} 2 O) 2~100 CF 2 C
The lubricant composition according to any one of claims 1 to 3 having a F ₃ structure.

Images