JP2021024923A - Fluorine grease composition - Google Patents

Abstract

To improve an oil separation degree of fluorine grease and to improve the storage stability.SOLUTION: A grease composition comprising a fluorinated oil and a silicone resin powder, in which the fluorinated oil is specifically a perfluorinated polyether, the silicone resin powder is contained in an amount of 20 to 80 mass% bases on the total mass of the fluorinated grease composition, and the silicone resin powder has a volume average particle diameter of 0.1 to 5.0 μm.SELECTED DRAWING: None

Description

The present invention relates to a fluorine grease composition containing a fluorine oil.

The grease composition is a semi-solid or solid lubricant at room temperature and is used for lubricating parts of various machines, especially bearings. The grease composition contains a base oil which is a lubricating oil component, a thickener, and an additive added as needed. Depending on the type of base oil, mineral oil-based grease, polyolefin-based grease, and fluorine It is classified into types such as grease.

Among the above greases, fluorine grease is a grease with excellent heat resistance, chemical resistance, low vapor pressure resistance, etc., can be used in a wide temperature range, and is not found in other types of grease. It has many excellent performances. Therefore, fluorine grease is used in a wide range of applications such as the nuclear industry, machinery, semiconductors, automobiles, and the space field.

Conventional fluorine grease mainly uses fluorine oil as a base oil and polytetrafluoroethylene (PTFE) as a thickener. However, this type of fluorine grease is known to have a high degree of oil release.

The degree of degreasing in grease is an index of the separability of the base oil of the grease in a static state, and the grease hardens when the base oil separates. If this progresses, the lubricity of the grease will be lost and it will not be usable, or it may cause machine failure or seizure. Therefore, the degree of oil release is an index of grease storage stability and life.

Regarding fluorine grease, JP-A-2019-77813 (Patent Document 1) has improved wear resistance, and JP-A-2017-19933 (Patent Document 2) has the purpose of improving heat resistance and rust prevention. However, none of them examined the improvement of the degree of oil release.

Japanese Unexamined Patent Publication No. 2019-77813 Japanese Unexamined Patent Publication No. 2017-19933

An object of the present invention is to improve the degree of oil release in a fluorine grease composition to improve storage stability.

That is, the present invention provides a fluorine grease composition containing a fluorine oil and a silicone resin powder.

The present invention provides the following aspects:
The above-mentioned fluorine grease composition in which the fluorine oil is a perfluoropolyether.
The above-mentioned fluorine grease composition in which the silicone resin powder is 20 to 80% by mass with respect to the total mass of the fluorine grease composition.
The above-mentioned fluorine grease composition in which the silicone resin powder has a volume average particle diameter of 0.1 to 5.0 μm.

In the fluorine grease composition of the present invention, by using a silicone resin powder as a thickener, the degree of oil release is improved and the storage stability is greatly increased. Since the fluorine grease composition of the present invention maintains other performances as fluorine grease, such as heat resistance, chemical resistance, and low vapor pressure resistance, it can be used for a long period of time in applications where fluorine grease can be used. Moreover, the stability during storage is high.

Further, the silicone resin powder used in the fluorine grease composition of the present invention does not use polytetrafluoroethylene (PTFE), which has been conventionally used as a thickener, and is therefore considered to be caused by polytetrafluoroethylene. It is possible to provide a highly safe fluorine grease composition that does not generate environmentally hazardous substances (perfluorooctanesulfonic acid (sometimes abbreviated as "PFOS") and perfluorooctanoic acid (sometimes abbreviated as "PFOA")). ..

The fluorine grease composition of the present invention needs to contain fluorine oil and silicone resin powder. In addition, other additives may be included, if desired. Hereinafter, each component will be described in detail.

<Fluorine oil>
In the fluorine grease composition of the present invention, the base oil is a fluorine oil, and a commercially available fluorine-based synthetic oil can be used. The fluorine oil is preferably a compound in which the hydrogen atom of the aliphatic hydrocarbon polyether is replaced with a fluorine atom, and specifically, perfluoropolyether (PFPE) can be preferably used. The perfluoropolyether may have either a linear structure or a side chain structure.

The perfluoropolyether may be either modified or unmodified, but a general unmodified perfluoropolyether is preferable. "Modification" is a chemical modification and refers to a change in at least a part of a constituent unit to change a chemical property. Modifications include, but are not limited to, carboxylic oxidation, alcoholization, amidation, ketone formation, amineation, and alkoxylation.

As the perfluoropolyether, a commercially available product can be preferably used. Specific examples of commercially available products include Demnum S series (manufactured by Daikin Industries, Ltd.), Krytox series (manufactured by DuPont Co., Ltd.), Fomblin Y series (manufactured by Solvay Specialty Polymers Japan), and Fomblin M series (manufactured by Solvay Specialty Polymers Japan). ) Etc. can be mentioned.

Further, in the present invention, a fluorine oil other than perfluoropolyether may be used, or two or more kinds of fluorine oils may be added. The type of fluorine oil to be used can be appropriately selected depending on the application in which the fluorine grease is used.

<Thickener (silicone resin powder)>
The present invention is characterized in that a silicone resin powder is used as the thickener. The silicone resin powder may be a powder of a silicone resin or a powder of a silicone rubber.

Examples of the shape of the silicone resin powder include a spherical shape, a rod shape, a plate shape, and an amorphous shape. Among these, a spherical shape is preferable because it is excellent in sustainability of a silky feeling. In the present invention, the spherical shape is not limited to a true sphere, but may have an elliptical cross section, but a true sphere is preferable.

The silicone resin is a compound having a siloxane skeleton, and its structure is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a linear structure, a cyclic structure, a branched structure, or a network structure. , Crosslinked structure, block copolymers of these, and the like. These may be used alone or in combination of two or more. Among these, a reticulated structure resin powder (reticulated silicone resin powder), a crosslinked resin powder (crosslinked silicone resin powder), a crosslinked silicone / reticulated silicone block copolymer powder, and / Alternatively, a powder obtained by coating these surfaces with polymethylsilsesquioxane particles is preferable.

In the silicone resin, the siloxane skeleton may be substituted with one or more substituents such as a polyether group, an epoxy group, an amino group, a carboxyl group, an aralkyl group, a methyl group and a phenyl group. Among these, a methyl group is preferable, and silsesquioxane having a methyl group is preferable.

The silicone resin powder may be the silicone resin powder alone, but may be coated with an inorganic powder such as titanium oxide, zirconium oxide, or iron oxide, or a silicone resin. May be good.

The volume average particle size of the silicone resin powder is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 0.1 to 5.0 μm, more preferably 0.5 to 3.0 μm. If the volume average particle size exceeds 5.0 μm, the sustainability of the silky feeling may be insufficient. On the contrary, it can be used even if it is less than 0.1 μm, but the silky feeling cannot be maintained. The volume average particle size can be measured with a laser diffraction / scattering particle size distribution measuring device (for example, LS13 320, manufactured by Beckman Coulter).

The method for obtaining the silicone resin powder is not particularly limited, and an appropriately synthesized one may be used, or a commercially available product may be used.

Specific examples of commercially available silicone resin powders include Shin-Etsu Silicone Powders KMP-600, KMP-601, KMP-602, KMP-605, X-52-7030, KMP-590, which are commercially available from Shin-Etsu Chemical Co., Ltd. Examples thereof include KMP-701, X-52-854, Z-52-1621, KMP-590, KMP-598, KMP-594 and X-52-875. The silicone resin powder is MSP-N030, MSP-SN03, MSP-N050, MSP-SN05, MSP-N080, MSP-SN08, MSP-SN08EIII, MSP-S110, MSP-A200 commercially available from Nikko Rika Co., Ltd. , MSP-A37, MSP-3500. Among these, Shin-Etsu Chemical's KMP-597, KMP-590, KMP-605, X-52-854, X-52-7030, X-52-854, Nikko Rika's MSP-N050, MSP-SN05, MSP-N080, MSP-SN08, and MSP-3500 are preferable in terms of volume average particle size.

In the fluorine grease composition of the present invention, the content of the silicone resin powder in the composition is not particularly limited and may be appropriately selected depending on the intended purpose, but with respect to the total mass of the fluorine grease composition. It is preferably blended in an amount of 20 to 80% by mass, more preferably 25 to 60% by mass, and most preferably 25 to 40% by mass. If the content of the silicone resin powder is less than 20% by mass, it has a drawback that the consistency is high and it flows, and if it exceeds 80% by mass, the consistency is low and it becomes hard and loses fluidity. Have.

<Other additives>
The fluorine grease composition of the present invention may contain other additives if necessary. Examples of the additive include rust preventives, antioxidants, corrosion inhibitors, extreme pressure agents, oily agents, solid lubricants and the like.

Examples of the rust preventive include sodium benzoate, sodium nitrite, sodium sebacate, and aromatic calcium sulfonate.

Examples of the antioxidant include phenol-based antioxidants such as 2,6-di-tertiary butyl-4-methylphenol and 4,4′-methylenebis (2,6-di-tertiary butylphenol), alkyldiphenylamines, and tri. Examples thereof include amine-based antioxidants such as phenylamine, phenyl-α-naphthylamine, phenothiazine, alkylated phenyl-α-naphthylamine and alkylated phenothiazine.

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

Examples of the extreme pressure agent include phosphorus compounds such as phosphoric acid ester, phosphite ester, and phosphate ester amine salt, sulfur compounds such as sulfides and disulfides, dialkyl dithiophosphate metal salts, and dialkyl dithiocarbamic acid metal salts. Sulfur-based compound metal salts and the like can be mentioned.

Examples of the oily agent include fatty acids or esters thereof, higher alcohols, polyhydric alcohols or esters thereof, aliphatic amines, fatty acid monoglycerides and the like. Examples of other solid lubricants include molybdenum disulfide, graphite, boron nitride, silane nitride and the like.

These additives are used in a proportion of 0.01 to 0.10% by weight, preferably 0.01 to 0.09% by weight, based on the total amount of the fluorooil and the silicone resin powder. .. If it is used in a proportion smaller than this, the effect of adding the additive is not observed, and even if it is used in a larger amount than this, the effect of addition is not observed, and conversely, the grease performance may be deteriorated.

<Fluorine grease>
To prepare the fluorine grease composition of the present invention, a predetermined amount of silicone resin powder and, if necessary, an additive are added to the fluorine oil, and the mixture is sufficiently stirred in a stirring kettle or the like, and then homogenized with a three-roll or high-pressure homogenizer. It is done by the method of doing. In some cases, it can be prepared simply by mixing.

Since the fluorine grease composition of the present invention uses a silicone resin powder as a thickener, the degree of oil release is improved and the storage stability is greatly increased. As already mentioned, the degree of oil release is an index of the separability of the base oil of the grease in a static state, and the grease hardens when the base oil separates. The measuring method is specified in "JIS K 2220: 2013 Grease 11 Oil Deletion Test Method" in the Japanese Industrial Standards, and in the embodiment of the present invention, the oil desorption degree after 30 hours at 200 ° C. was measured.

Since the fluorine grease of the present invention maintains other performances as fluorine grease, such as heat resistance, chemical resistance, and low vapor pressure resistance, it can be used for a long period of time in applications where fluorine grease can be used, and can be stored. Increases time stability. Further, since the fluorine grease composition of the present invention does not use polytetrafluoroethylene (PTFE), which has been conventionally used as a thickener, it does not generate environmentally hazardous substances (PFOS and PFOA), and is highly safe fluorine grease. The composition can be provided. PFOS and PFOA are persistent organofluorine compounds that undergo little biodegradation and remain in the environment for a long time, and it is considered that they should not be present.

Hereinafter, the fluorine grease composition according to the present invention will be described with reference to specific examples, but the present invention is not limited thereto.

Examples 1-10 and Comparative Examples 1-2
As a base oil component (perfluoropolyether), base oil A: Daikin Industries Co., Ltd. product name Demnum S-200, so that the immiscibility of each component is 110 to 330 at the ratio shown in Table 1. Oil B: Solvay Specialty Polymers Japan Co., Ltd. Product name: Fomblin YHVAC 40/11), as a thickener (silicone resin powder), thickener A: Shin-Etsu Chemical KMP-594, thickener B: Shin-Etsu KMP-590 manufactured by Kagaku Co., Ltd., thickener C: X-52-854 manufactured by Shin-Etsu Chemical Co., Ltd., thickener D: MSP-SN05 manufactured by Nikko Rika Co., Ltd.) were uniformly mixed and treated with a three-roll mill. As a comparative example, PTFE (polytetrafluoroethylene) was used instead of the silicone resin powder to obtain a grease composition. The numerical values shown in Table 1 represent parts by mass. As a comparative example, a mixture of perfluoropolyether and PTFE (volume average particle size 2 μm) was used.

For each Example and Comparative Example, the grease composition was evaluated by the following method, and the results are shown in Table 1.

Unsaturated Consistency The unsaturated consistency was measured by JIS K2220.7.
Degree of degreasing The degree of degreasing after 30 hours at 200 ° C. was measured by JIS K222.11.

As is clear from Table 1, the fluorine grease of the present invention has an oil release degree of 10 or less in all, and the oil release degree of Comparative Example 1 exceeds 10, so that the storage stability is improved. I understand that.

In the fluorine grease composition of the present invention, by using a silicone resin powder as a thickener, the degree of oil release is improved and the storage stability is greatly increased. Since the fluorine grease composition of the present invention maintains other performances as fluorine grease, such as heat resistance, chemical resistance, and low vapor pressure resistance, it can be used for a long period of time in applications where fluorine grease can be used. Therefore, the fluorine grease composition of the present invention is used in a wide range of applications such as the nuclear industry, machinery, semiconductors, automobiles, and the space field.

Claims (4)

Fluorine grease composition containing fluorine oil and silicone resin powder. The fluorine grease composition according to claim 1, wherein the fluorine oil is a perfluoropolyether. The fluorine grease composition according to claim 1 or 2, wherein the silicone resin powder is 20 to 80% by mass with respect to the total mass of the fluorine grease composition. The fluorine grease composition according to any one of claims 1 to 3, wherein the silicone resin powder has a volume average particle diameter of 0.1 to 5.0 μm.