JP5330774B2 - Grease composition for resin lubrication - Google Patents

Abstract

Grease composition for use in resin lubrication incorporating into a grease base material which includes a base oil and a fatty acid metal salt thickener at least one saturated or unsaturated fatty acid having from 8 to 22 carbon atoms and/or fatty acid metal salt, being a metal salt of a linear saturated fatty acid having from 8 to 14 carbon atoms or a metal salt of an unsaturated fatty acid having from 16 to 22 carbon atoms and from 1 to 4 unsaturated groups, the metal having a valence of from 1 to 4 excluding fatty acid metal salts used for the thickener. The grease composition of the present invention gives satisfactory lubrication properties between resin and resin or resin and other material such as a metal.

Description

  The present invention relates to a resin-lubricating grease composition used at a lubrication site where a resin material is used and rolling or sliding occurs.

  In recent years, the use of resin materials from various viewpoints such as weight reduction, cost reduction, low friction, or recycling has become prominent in parts of various industrial machines including the automobile industry. In the diversification, many new problems have occurred and various techniques have been improved.

  For example, movable parts of automobile electric door mirrors, sliding parts of telescopic shafts of steering, various sliding parts such as rack guides of R & P steering, power transmission gears of electric power steering devices, various actuators, sliding parts inside air cylinders , Linear guides for machine tools, retainers for ball screws, retainers for various bearings, sliding parts for crane booms, resin gears for acoustic equipment such as radio cassettes, video tape recorders, CD players, printers, copiers, fax machines, etc. In a resin gear part of an OA device, a sliding part of various electric switches, and the like, there is a lubrication point where a resin and a resin or a material other than a resin such as a resin and a metal functions in a contact state.

Conventionally, in the field of lubrication, most of the components of machinery have been metal materials, so research on friction and wear between metals such as iron, aluminum, their alloys, brass, bronze, etc. has a long history, Many technologies are accumulated through deep experience and knowledge.
For example, extreme pressure agents and antiwear agents containing elements such as phosphorus and sulfur are effective for friction and wear between metals, and these additives actively form a film by causing a chemical reaction with the metal surface. It is well known that it forms functions such as reducing friction and wear and preventing seizure. Engine oil, gear oil, and high-performance industrial lubricants and greases have these technologies. Widely applied.

However, despite the short history of lubrication technology between resins or between different materials such as resin and metal, in recent years the use has expanded and diversified in response to various demands for lubricating grease. However, the current situation is that we cannot always provide satisfactory technology.
For example, when the technology using the phosphorus-based or sulfur-based additive effective for friction and wear between the metals described above is applied to the lubrication points between the resins or between the resin and the metal material, the metal can be obtained between the metals. However, there are many cases where the friction and wear resistance performance deteriorates and the life of the machine parts is shortened.

  In the case of resin, the chemical activity at the interface is weak compared to metal, so there is almost no reaction with organic additives such as phosphorus and sulfur on the sliding surface, and adsorption is weak. For this reason, it is considered that the effect on friction and wear is small, and therefore the friction reducing action is weak. Also, when used in an environment where the temperature rises forcibly, the active sulfur and phosphorus of these additives penetrate into the resin, causing cracks and embrittlement, or promoting friction and wear. There is a case where a reverse reaction occurs.

  In order to improve the lubrication state between the above resins or different materials such as resin and metal, a mixture of alkylene oxide-polyhydric alcohol addition polymerization oligomer and chain hydrocarbon oligomer and quaternary is added to lithium grease. A plastic lubricating grease containing an ammonium salt-containing clay mineral and a dispersant has been proposed (Patent Document 1), a base oil such as poly-α-olefin oil, mineral oil, highly refined mineral oil, and metal soap or metal composite soap. Although a technique of a grease composition for resin lubrication containing a thickener and a nonpolar wax or a polar wax is disclosed (Patent Document 2), further improvement is desired.

Japanese Patent Publication No. 6-43594 JP-A-2005-54024

  The present invention can reduce friction and provide good lubricity at a lubrication location where rolling or sliding occurs where at least one of the opposite materials is made of a resin material such as resin and resin or different materials such as resin and metal. An attempt is made to obtain a resin lubricating grease composition.

  The inventors of the present invention have previously studied and investigated the lubrication behavior of resins based on the theory of interfacial chemistry, and the like. The weak electricity generated at the interface of the resin interacts with certain saturated or unsaturated fatty acids and fatty acid metal salts added to the grease, and this additive also acts as a binder with the grease. The present inventors have found that a lubricating film can be more reliably formed and maintained at the interface with the opposite material and that friction can be reduced and good lubricity can be obtained, thereby completing the present invention.

The present invention relates to a grease base material consisting of thickener fatty acid metal salt containing a base oil and a hydroxyl group, a saturated fatty acid having 8 to 16 carbon atoms and / or unsaturated fatty acids having 8 to 22 carbon atoms (provided that the hydroxyl group And / or a metal salt of a linear saturated fatty acid having 8 to 14 carbon atoms or a metal salt of an unsaturated fatty acid having 16 to 22 carbon atoms having 1 to 4 unsaturated groups. In addition, at least one kind of fatty acid metal salt (excluding a fatty acid metal salt containing a hydroxyl group) having a valence of 1 to 4 is contained in an amount of 0.1 to 10% by mass based on the total amount of the grease composition . Thus, a grease composition for resin lubrication is obtained.

Examples of the metal of the fatty acid metal salt include lithium, sodium, potassium, magnesium, calcium, zinc, aluminum, and lead.
And said saturated or unsaturated fatty acid and / or fatty acid metal salt excludes the fatty acid or fatty acid metal salt containing a hydroxyl group, and the total content of at least one kind thereof is based on the total amount of the grease composition. And about 0.1 to 10% by mass. Furthermore, the fatty acid metal Shiozo thickener containing a hydroxyl group, can be used in combination calcium phosphate as a thickening agent.

  According to the present invention, in a lubricating part such as rolling or slipping between members, one of which is made of a resin material, friction can be further reduced and good lubricity can be obtained. As a grease composition for resin lubrication, Can be used widely.

The base oil in the present invention is generally used as a base oil for lubricating oil or a base oil for grease, and is not particularly limited. For example, mineral oil, synthetic oil, animal and vegetable oil, and These mixed oils are mentioned.
In particular, base oils belonging to Group 1, Group 2, Group 3, Group 4, etc. in the API (American Petroleum Institute) base oil category can be used alone or as a mixture.

For Group 1 base oils, for example, paraffin obtained by applying a suitable combination of solvent refining, hydrotreating, dewaxing, etc., to a lubricating oil fraction obtained by atmospheric distillation of crude oil There are mineral oils.
For Group 2 base oils, for example, paraffinic mineral oil obtained by appropriately combining refining means such as hydrocracking and dewaxing for lubricating oil fractions obtained by atmospheric distillation of crude oil There is. Group 2 base oils refined by hydrorefining methods such as the Gulf Company method have a total sulfur content of less than 10 ppm and an aroma content of 5% or less, and can be suitably used in the present invention.

  Group 3 base oil and Group 2 plus base oil include, for example, a paraffinic mineral oil produced by advanced hydrorefining and a dewaxing process for a lubricating oil fraction obtained by atmospheric distillation of crude oil. There are base oils refined by the ISODEWAX process for converting and dewaxing the produced wax to isoparaffins, and base oils refined by the mobile WAX isomerization process, and these can also be suitably used in the present invention.

  Specific examples of synthetic oils include, for example, polyolefins, polyalkylene glycols such as polyethylene glycol and polypropylene glycol, diesters such as di-2-ethylhexyl sebacate and di-2-ethylhexyl adipate, trimethylolpropane ester and pentaerythritol ester. Polyol esters, perfluoroalkyl ethers, silicone oils, polyphenyl ethers and the like.

  The polyolefin includes polymers of various olefins or hydrides thereof. Any olefin may be used, and examples thereof include ethylene, propylene, butene, and α-olefin having 5 or more carbon atoms. In the production of polyolefin, one of the above olefins may be used alone, or two or more may be used in combination. Particularly preferred are polyolefins called poly α-olefins (PAO), which are Group 4 base oils.

  GTL (Gas Liquid) synthesized by the Fischer-Tropsch method, which is a natural gas liquid fuel technology, has an extremely low sulfur content and aromatic content compared to mineral oil base oil refined from crude oil. Is extremely high, so that it has excellent oxidation stability and very low evaporation loss, and can be suitably used as the base oil of the present invention.

Representative examples of animal and vegetable oils include castor oil and rapeseed oil.
The various oils described above can be used alone or in combination as a base oil, but the above are merely examples, and the present invention is not limited thereby.

As the thickener in the present invention , a fatty acid metal salt containing a hydroxyl group is used. This fatty acid metal salt is a combination of a fatty acid and a metal, and is usually called a metal soap, such as lithium soap, sodium soap, potassium soap, magnesium soap, calcium soap, barium soap, Aluminum soap, zinc soap, lead soap, and complex soaps of these can be exemplified, and these are used alone or in combination.
Optionally, it is also possible to use a thickener in the fatty acid metal salt containing a hydroxyl group in combination with tricalcium phosphate.

The additive added to the grease base material including the base oil and the thickener described above is a saturated fatty acid having 8 to 16 carbon atoms and / or an unsaturated organic fatty acid having 8 to 22 carbon atoms and / or 8 to 8 carbon atoms. 14 is a metal salt of a linear saturated fatty acid that is 14, or a metal salt of an unsaturated fatty acid having 16 to 22 carbon atoms having 1 to 4 unsaturated groups, wherein the metal is a monovalent to tetravalent fatty acid. It is a metal salt, The fatty acid of the said fatty acid and fatty acid metal salt does not have a hydroxyl group.

Examples of the fatty acid that is a starting material for the saturated or unsaturated fatty acid and fatty acid metal salt in the present invention include, for example, caprylic acid, pelargonic acid, capric acid, lauric acid, Linderic acid, myristic acid, tuzuic acid, and fisetreic acid. , Myristoleic acid, pentadecylic acid, palmitic acid, palmitoyl acid, margaric acid, stearic acid , petrothelic acid, oleic acid, elaidic acid, vaccenic acid, linoleic acid, linolenic acid, eleostearic acid , tuberculostearic acid, arachidic acid Icosadienoic acid, icosatrienoic acid, arachidonic acid, behenic acid, lignoceric acid, nervonic acid, hexadocosanoic acid, octadocosanoic acid, erucic acid and the like.

  When the metal in the fatty acid metal salt of the present invention is lithium, sodium, potassium, magnesium, calcium, zinc, aluminum, lead or the like, the frictional force between the materials is reduced at the lubrication point between the resin and the material other than the resin. The effect is great, and these metals and fatty acids can be easily reacted, and the fatty acid salts are chemically stable and easily maintain a good lubricating state.

  The total content of one or more of the above-mentioned saturated or unsaturated fatty acids and fatty acid metal salts may be added in a range of about 0.1 to 10% with respect to the total amount of the grease composition. Is preferably used at about 1 to 5% by mass. If the amount is less than 0.1% by mass, the electrochemical action on the interface is too small and the effect of reducing the friction coefficient is low. On the other hand, if the amount is more than 10% by mass, it becomes difficult to effectively exhibit the inherent performance of the grease composition (for example, viscoelasticity, shear stability, heat resistance, etc.), and the stable state will be maintained for a long time Tends to be difficult and costly.

Further, the grease composition of the present invention may further contain other additives such as an antioxidant, a rust inhibitor, an oily agent, an extreme pressure agent, an antiwear agent, a solid lubricant, a metal deactivator, and a polymer as appropriate. Can be added.
Examples of the antioxidant include 2,6-di-tbutyl-4-methylphenol, 2,6-di-tbutylparacresol, P, P′-dioctyldiphenylamine, N-phenyl-α-naphthylamine, and phenothiazine. and so on.
Examples of the rust inhibitor include oxidized paraffin, carboxylic acid metal salt, sulfonic acid metal salt, carboxylic acid ester, sulfonic acid ester, salicylic acid ester, succinic acid ester, sorbitan ester, and various amine salts.

  Examples of oily agents, extreme pressure agents, and antiwear agents include zinc sulfide dialkyldithiophosphate, zinc sulfide diallyldithiophosphate, zinc sulfide dialkyldithiocarbamate, zinc sulfide diallyldithiocarbamate, sulfurized dialkyldithiophosphate molybdenum, sulfide diallyldithiophosphate molybdenum. , Sulfurized dialkyldithiocarbamate molybdate, diallyldithiocarbamate molybdate, organic molybdate complex, sulfurized olefin, triphenyl phosphate, triphenyl phosphorothioate, tricresyl phosphate, other phosphate esters, sulfurized oils and fats, etc. .

Examples of the solid lubricant include molybdenum disulfide, graphite, boron nitride, melamine cyanurate, PTFE (polytetrafluoroethylene), tungsten disulfide, mica, and graphite fluoride.
Examples of metal deactivators include N, N'disalicylidene-1,2-diaminopropane, benzotriazole, benzimidazole, benzothiazole, thiadiazole and the like.
Examples of the polymer include polybutene, polyisobutene, polyisobutylene, polyisoprene, and polymethacrylate.
In addition, all the above-mentioned other additives are examples, and are not limited thereto.

  In the present invention, in the lubricating part where one of the opposing members is made of a resin material and rolling or sliding is observed, friction can be reduced and good lubricity can be obtained. It is essential that one member is a resin, but the member facing the resin is not only resin, but also various metal materials such as iron, copper, aluminum and other metals, and alloys thereof, rubber Nonpolar materials such as glass, ceramic, etc. may be used and are not particularly limited.

  In addition, the resin material can be used for various materials regardless of general-purpose plastics and engineering plastics. For example, polyamide, polyacetal, polycarbonate, polyethylene terephthalate, polybutylene terephthalate, polybutylene naphthalate, polyphenylene ether , Polyphenylene sulfide, fluorine resin, polyarylate, polyamide imide, polyether imide, polyether ether ketone, polysulfone, polyether sulfone, polyimide, polystyrene, polyethylene, polypropylene, phenol resin, AS resin, ABS resin, AES resin, AAS Resin, ACS resin, MBS resin, polyvinyl chloride resin, epoxy resin, diallyl phthalate resin, polyester resin, methacrylic resin Fat, can be mentioned ABS / polycarbonate alloys such as, but not limited thereto.

EXAMPLES Hereinafter, although an Example and a comparative example demonstrate this invention in detail, this invention is not limited at all by these Examples.
In preparing Examples and Comparative Examples, the following materials were prepared.
1. Base oil A: mineral oil having a kinematic viscosity at 40 ° C. of 101.1 mm ² / s.
2. Base oil B: a poly α-olefin oil having a kinematic viscosity at 40 ° C. of 31.2 mm ² / s.
3. Base oil C: a highly refined oil having a kinematic viscosity at 40 ° C. of 47.08 mm ² / s, a viscosity index of 146,% CA of 1 or less,% CN of 11.9 and% CP of 85 or more.
4). Thickener A: lithium 12 hydroxy stearate soap obtained by reaction of 12 hydroxystearic acid with lithium hydroxide in base oil.
5. Thickener B: Diurea obtained by a synthesis reaction of 2 moles of octylamine and 1 mole of MDI (4,4'-diphenylmethane diisocyanate) in the base oil.
6). Thickener C: Bentonite obtained by swelling and gelling bentonite with an organic solvent in base oil.
7). Thickener D: sodium terephthalate which is obtained by the reaction of methyl N-octadecyl terephthalate and sodium hydroxide in the base oil.
8). Thickener E: [Ca ₃ (PO ₄ ) ₂ ] ₃ · Ca (OH) ₂ is obtained by swelling and gelling tricalcium phosphate having a hydroxyapatite composition represented by an organic solvent.

Grease compositions were prepared using base oils and thickeners in the blending ratios shown in Examples 1 to 9 and Reference Examples 1 to 4 in Tables 1 to 3, and various fatty acids and / or fatty acid metal salts were added as grease compositions. Got.
Specifically, for the grease using the thickener A (lithium 12 hydroxystearate soap) of Examples 1 to 8, the base oil, the thickener, and the like so that the total amount of the grease composition becomes 1000 g. In addition, various fatty acids or fatty acid metal salts as additives were weighed in advance at the blending ratios shown in Tables 1-2. After that, a base oil, 12 hydroxystearic acid, lithium hydroxide and a small amount of water are filled in a production tank dedicated to grease with an internal volume of 3 kg, sealed, and subjected to a saponification reaction with stirring and heating. Increase to a pressure of 35 MPa. Thereafter, it is gradually dehydrated and further heated to 215 ° C. to dissolve the contents. Then, after cooling at a constant rate and growing soap fibers, the various fatty acids or fatty acid metal salts of the above additives were put in and homogenized to obtain grease compositions for resin lubrication of Examples 1-6. .
In addition, the fatty acid metal salt described in Tables 1 to 3 used a product obtained by reacting a fatty acid and a metal in advance at a molar ratio described in Tables 1 to 3 (the same applies to the following Table 4 Comparative Examples). ).

About the grease which used other thickeners B-E together with the thickener A (lithium 12 hydroxystearate soap) shown in Example 9 of Tables 2-3 and Reference Examples 1-4 , each thickener B A grease prepared as follows using ~ E is prepared separately, and mixed at room temperature with a blending ratio of thickeners shown in Tables 2-3 in a dedicated grease manufacturing pot, and various fatty acids or fatty acid metals The grease composition for resin lubrication of Example 9 and Reference Examples 1 to 4 was obtained by applying a homogenizer treatment with salt.

  For greases using Thickener B (Urea), Table 2 shows the base oil, Thickener B, and various fatty acids or fatty acid metal salts as additives so that the total amount of the grease composition is 1000 g. Weighed in advance at the blending ratio shown in ~ 3. After that, part of the base oil and MDI (4,4'-diphenylmethane diisocyanate), which is the raw material of the thickener B, are put into a 3 kg dedicated production tank for grease, and the temperature is raised to 60 ° C. while stirring with heating. The remaining base oil is mixed with octylamine previously mixed and dissolved, reacted, further heated up to 180 ° C., cooled at a constant rate, and the above-mentioned various fatty acids or fatty acid metal salts are stuck and homogenized. Thus, a grease composition was obtained.

  For the grease composition using the thickener C (bentonite), Table 3 shows the base oil, the thickener C, and various fatty acids or fatty acid metal salts as additives so that the total amount of the composition becomes 1000 g. Were weighed in advance at the blending ratio shown below. Thereafter, a base oil, a bentonite of a thickener C and an organic solvent for accelerating gelation were put in a production tank dedicated to grease having an internal capacity of 3 kg, and the temperature was gradually raised to 150 ° C. while stirring with heating. The organic solvent was sufficiently evaporated and uniformly dispersed and swollen, then cooled at a constant rate, and the above-mentioned various fatty acids or fatty acid metal salts were applied and homogenized to obtain a grease composition.

  For greases using Thickener D (sodium terephthalate), Table 3 shows the base oil, Thickener D, and fatty acid metal salt as an additive so that the total amount of the grease composition is 1000 g. Weighed in advance at the blending ratio shown. After that, the base oil and methyl N-octadecyl terephthalate, which is the raw material of the thickener D, are filled in a 3 kg grease dedicated production kettle and stirred and dispersed in water at a temperature of 90 ° C. while stirring with heating. The previously prepared sodium hydroxide suspension is put into the kettle, reacted while gradually warming and stirring, and the temperature is raised to 170 ° C. Thereafter, the mixture was cooled at a constant rate, and the fatty acid metal salt was put in and homogenized to obtain a grease composition.

  For grease compositions using Thickener E (tricalcium phosphate), the base oil, Thickener E, and fatty acid metal salt as additive are represented so that the total amount of the composition is 1000 g. It measured beforehand in the mixture ratio shown in 3. FIG. After that, base oil, tricalcium phosphate, and organic solvent for promoting gelation were put into a production tank dedicated to grease having an internal capacity of 3 kg, and the temperature was gradually raised to 150 ° C. while heating and stirring. Is vaporized and homogeneously dispersed and swollen. Thereafter, the mixture was cooled at a constant rate, and the fatty acid metal salt was put in and homogenized to obtain a grease composition.

  For Comparative Examples 1 to 6, various raw materials were weighed at the blending ratios shown in Table 4, and various grease compositions were manufactured according to the manufacturing methods described in the above examples.

In order to compare the properties and performance of Examples and Comparative Examples, the following measurements and tests were performed.
1. Consistency: Measured according to JIS K2220-7.
2. Dropping point: Measured according to JIS K2220-8.
3. Kinematic viscosity of base oil: Measured according to JIS K2283.
4). Friction test: A Bowden friction test was performed. That is, a friction coefficient between a material (test material 1a) other than a resin facing the resin (test material 1b) was measured under the following test conditions using a Bowden friction test apparatus.
(1) Test material 1a: Material: Steel material S45C and copper alloy ALBC2.
Dimensions: Pin shape with outer diameter of 5.0mm and length of 24mm.
r = 2.5mm hemisphere with a contact surface of about 1.0mm in diameter
It has been processed.
(2) Test material 1b: Material: Polyamide resin (manufactured by Toray Industries, Inc., 66 nylon / amilan) and
Polyacetal resin (DuPont Delrin 500P).
Dimensions: A plate-like body having a length of 200 mm and a width of 52 mm.
(3) Temperature: 25 ° C
(4) Sliding speed: 1.0 mm / s
(5) Load: 870g
(6) Contact surface pressure: 10 MPa
In addition, between the polyamide resin and the steel material, the Bowden type friction test was performed for all examples and all the comparative examples, and some tests were performed between the polyacetal resin and the copper alloy.

(Test results)
As shown in Tables 1-4.
(Discussion)
The grease compositions for resin lubrication of Examples 1 to 9 and Reference Examples 1 to 4 all show a semi-solid grease, a consistency of 267 to 290, an appropriate hardness value, and a dropping point. It was in a good state at 177 to 210 ° C. Further, the friction coefficient between polyamide resin and steel in the Bowden friction test is 0.060 to 0.069, and the friction coefficient between polyacetal resin and copper alloy is also uniformly low as 0.062 to 0.066. It can be seen that various materials and materials other than resins such as copper alloys and steel exhibit good lubricating performance.
On the other hand, the grease compositions of Comparative Examples 1 to 6 all show a semi-solid grease, a consistency of 265 to 281 and an appropriate hardness value, and a dropping point of 180 to 207 ° C in a good state. However, the friction coefficient between the polyamide resin and the steel in the Bowden friction test is 0.082 to 0.099, and the friction coefficient between the polyacetal resin and the copper alloy is also uniformly 0.099 and 0.101. It is high, and it is inferior to the examples in the lubrication state between various resins and materials other than resin such as copper alloy and steel, and it can be seen that the effect of improving the lubrication performance is not obtained.
From these results, the grease composition for resin lubrication of the present invention shows good lubrication performance.

Claims (3)

Excluding the grease base material made of a thickener of a fatty acid metal salt containing a base oil and a hydroxyl group, a saturated fatty acid having 8 to 16 carbon atoms and / or unsaturated fatty acids having 8 to 22 carbon atoms (provided that the fatty acid containing a hydroxyl group And / or a metal salt of a linear saturated fatty acid having 8 to 14 carbon atoms or a metal salt of an unsaturated fatty acid having 16 to 22 carbon atoms having 1 to 4 unsaturated groups, Resin in which at least one kind of fatty acid metal salt (excluding the fatty acid metal salt used as a thickener) is 0.1 to 10% by mass with respect to the total amount of the grease composition. Grease composition for lubrication.   The grease composition for resin lubrication according to claim 1, wherein the metal of the fatty acid metal salt is lithium, sodium, potassium, magnesium, calcium, zinc, aluminum, or lead. The grease composition for resin lubrication according to claim 1 or 2 , further comprising calcium phosphate as a thickener.