JP5473627B2 - Grease composition - Google Patents

Description

  The present invention relates to a grease composition, and more particularly to a grease composition capable of imparting a lubricating action to a resin surface.

  Conventionally, grease has been used as a lubricant composition used for gears, sliding parts, and the like.

  In recent years, for the purpose of reducing the weight and cost of automobile parts, home appliances, electronic information devices, OA devices, etc., resins are often used as gears and sliding members used in these.

  For the purpose of imparting lubricity to the surface of such a resin member, Patent Document 1 discloses a sarcosine derivative rust inhibitor, carbon, oxygen, hydrogen in a grease composition mainly composed of a base oil and a thickener. There is disclosed a grease composition characterized in that either one or both of phenolic antioxidants composed of only three atoms are added. According to the grease composition described in Patent Document 1, since an antioxidant and / or a rust preventive agent that does not have a functional group that adversely affects various resin members is used, a resin-made lubricating member It is possible to improve the oxidation stability of grease and the rust prevention of metal parts without adverse effects such as stress cracking on the resin casing member.

On the other hand, for the purpose of improving torque stability under durability conditions, a lubricant using a high-viscosity base oil (40 ° C. kinematic viscosity: 400-2500 mm ² / s) is often used. When a lubricant is used, there is a problem that a torque increase occurs at a low temperature such as 5 ° C. or less.

  In order to solve such problems, Patent Document 2 discloses (i) a chain hydrocarbon synthetic oil containing 70% by weight or more of a chain hydrocarbon synthetic oil (as a grease having both durability and low temperature properties). Α-olefin co-oligomer and / or α-olefin copolymer (37-12000 cSt / 100 ° C.) 5 to 55 wt% and acid-modified α-olefin / ethylene co-oligomer (100 to 8 to 35 cSt / 40 ° C.) (360 to 20000 cSt / 40 ° C.) 3 to 30% by weight of a mixed base oil, (ii) 1 to 20 parts by weight of a higher fatty acid lithium salt, and (iii) a quaternary amino group-containing organic compound A grease containing 0.5-8 parts by weight of a treated lipophilic synthetic fluoromica is described.

  Patent Document 3 discloses a grease obtained by adding a specific ethylene / α-olefin copolymer to a base oil as a grease having both excellent low-temperature performance and flexibility (implementation). See example).

  However, the invention described in Patent Document 2 uses a relatively low-viscosity chain hydrocarbon oil to improve low-temperature properties, and in a grease composition having a poly-α-olefin as a main base oil at low temperature. A method for achieving both stability and torque stability under durability is not disclosed.

  In Patent Document 3, there is neither disclosure nor suggestion of means for improving torque stability under durability conditions.

JP 2003-246996 A Japanese Patent Laid-Open No. 6-145485 Special table 2008-540698

  Accordingly, an object of the present invention is to provide a grease composition having a poly-α-olefin as a main base oil, which can achieve both low temperature properties and torque stability under durable conditions.

  In order to solve the above problems, the present inventors provide a grease composition according to the following configuration.

(1) A grease composition comprising a base oil containing a poly-α-olefin and an ethylene-α-olefin copolymer, and a thickener,
40 ° C. kinematic viscosity of the poly-α-olefin is in the range of 18 to 400 mm ² / s,
The number average molecular weight of the ethylene-α-olefin copolymer is in the range of 40,000 to 200,000, and the blending amount is in the range of 4 to 12% by mass with respect to the entire grease composition,
The base oil has a 40 ° C. kinematic viscosity in the range of 400 to 2500 mm ² / s,
The thickener is a total of 2 to 8% by weight of alkali metal soap and / or alkali metal composite soap based on the whole grease composition, or 15 to 25% by weight of alkaline earth based on the whole grease composition. metal-based composite soap der is,
A grease composition applied to a contact portion between a resin material and another resin material or a metal material .

(2) The grease composition according to (1), wherein the thickener is 2 to 8% by mass of an alkali metal soap and / or an alkali metal composite soap with respect to the entire grease composition.

(3) The grease composition according to (1) or (2), wherein the alkali metal is lithium.

(4) The grease composition according to (1), wherein the alkaline earth metal is barium.

(5) The grease composition according to any one of (1) to (4), wherein the penetration (JIS K2220.7) is 265 to 385.

  According to the grease composition of the present invention, excellent low-temperature performance and torque stability under durability conditions can be realized.

  Hereinafter, the present invention will be described in detail in accordance with embodiments for carrying out the present invention.

Base oil In the grease composition according to the present invention, the base oil contains poly-α-olefin and an ethylene-α-olefin copolymer, and the kinematic viscosity at 40 ° C. is 400 to 2500 mm ² / s. Features.

  In the grease composition according to the present invention, the poly-α-olefin refers to a polymer obtained by homopolymerization or copolymerization of one or more monomers of α-olefin having 3 or more carbon atoms. .

  Here, although it does not restrict | limit especially as an alpha olefin, Preferably it is C3-C30, More preferably, it is C4-C20, More preferably, a C6-C16 linear terminal olefin is mention | raise | lifted. . More specifically, examples thereof include propylene, 1-butene, 1-pentene, 1-hexene and the like.

The properties of these poly-α-olefins can be appropriately selected according to the use conditions, but those having a kinematic viscosity (40 ° C.) of 18 to 400 mm ² / s, more preferably 30 to 400 mm ² / g are preferred. Used. If the kinematic viscosity (40 ° C.) of the poly-α-olefin is less than 18 mm ² / s, the heat resistance is deteriorated, and if it exceeds 400 mm ² / s, the torque at low temperatures may increase.

  The degree of polymerization of the poly-α-olefin is not particularly limited, and includes those usually called oligomers. Moreover, poly- (alpha) -olefin may be used individually by 1 type, and 2 or more types may be mixed and used for it.

  In the present invention, the ethylene-α-olefin copolymer refers to a copolymer having ethylene and one or more α-olefins having 3 or more carbon atoms as constituent monomers.

  Here, the α-olefin in the ethylene-α-olefin copolymer is not particularly limited, but preferably has 3 to 30 carbon atoms, more preferably 4 to 20 carbon atoms, still more preferably 6 to 16 carbon atoms. These are linear terminal olefins. More specifically, examples thereof include propylene, 1-butene, 1-pentene, 1-hexene and the like. In addition, a poly-alpha-olefin may be used individually by 1 type, and may use 2 or more types. In addition, the ethylene-α-olefin copolymer may have any structure of a random copolymer, an alternating copolymer, a periodic copolymer, and a block copolymer.

  The number average molecular weight of the ethylene-α-olefin copolymer needs to be 40000 or more. This is because when the number average molecular weight of the ethylene-α-olefin copolymer is less than 40,000, the torque at a low temperature increases. The upper limit of the number average molecular weight of the ethylene-α-olefin copolymer is preferably 200000. When the number average molecular weight exceeds 200,000, the shear stability may be deteriorated. Moreover, a preferable weight average molecular weight is the range of 10,000-120,000.

  As a compounding quantity of an ethylene-alpha-olefin copolymer, it is preferable that it is 4-12 mass% with respect to the whole grease composition. When the blending amount of the ethylene-α-olefin copolymer is less than 4% by mass, the torque at low temperatures may increase. On the other hand, if it exceeds 12% by mass, the base oil viscosity increases and the torque at low temperatures may increase.

And the poly -α- olefin, as the 40 ° C. kinematic viscosity of the mixed base oil of ethylene -α- olefin copolymer is ^preferably in the range of 400mm ² / s~2500mm 2 / s. When the kinematic viscosity is less than 400 mm ² / s, the adhesion to the resin is lowered, and the torque stability under durability conditions may be lowered. Moreover, when it exceeds 2500 mm < ² > / s, there exists a possibility that the torque at the time of low temperature may rise.

Thickeners Thickeners used in the present invention are alkali metal soaps, alkali metal complex soaps, and alkaline earth metal complex soaps.

  Here, the alkali metal soap refers to a soap obtained by saponifying a single carboxylic acid or ester with an alkali metal hydroxide such as lithium, sodium or potassium. The alkali metal complex soap refers to a soap obtained by saponifying a plurality of carboxylic acids or esters with an alkali metal hydroxide such as lithium, sodium, or potassium. The alkaline earth metal composite soap is a soap obtained by saponifying a plurality of carboxylic acids or esters with a hydroxide of an alkaline earth metal such as magnesium, calcium, strontium or barium.

  Specific examples of the alkali metal soap include crude fatty acids obtained by hydrolyzing fats and oils to remove glycerin, monocarboxylic acids such as stearic acid, monohydroxycarboxylic acids such as 12-hydroxystearic acid, azelaic acid, sebacic acid, etc. And a product obtained by reacting an aromatic carboxylic acid such as dibasic acid, terephthalic acid, salicylic acid, benzoic acid or the like with a lithium compound such as lithium hydroxide. Among these, lithium soaps using stearic acid or 12-hydroxystearic acid are suitable.

  Specific examples of the alkaline (earth) metal composite soap include fatty acids such as stearic acid, oleic acid, and palmitic acid and / or hydroxy fatty acids having 12 to 24 carbon atoms having one or more hydroxyl groups in the molecule, At least one selected from the group consisting of aromatic carboxylic acids, aliphatic dicarboxylic acids having 2 to 20 carbon atoms (more preferably 4 to 12 carbon atoms) and carboxylic acid monoamides, for example, lithium hydroxide, barium hydroxide What is obtained by making it react with lithium compounds, such as these, is mention | raise | lifted. The alkali metal composite soap is more preferable as a thickener because it has better heat resistance than the alkali metal soap.

  The hydroxy fatty acid having 12 to 24 carbon atoms is not particularly limited, and examples thereof include 12-hydroxystearic acid, 12-hydroxylauric acid, and 16-hydroxypalmitic acid. Among these, 12-hydroxystearic acid is particularly preferable. Acid is preferred.

  Examples of the aromatic carboxylic acid include benzoic acid, phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, pyromellitic acid, salicylic acid, p-hydroxybenzoic acid and the like.

  The aliphatic dicarboxylic acid having 2 to 20 carbon atoms is not particularly limited, and examples thereof include oxalic acid, malonic acid, succinic acid, methyl succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, and sebacin. Acid, nonamethylene dicarboxylic acid, decamethylene dicarboxylic acid, undecane dicarboxylic acid, dodecane dicarboxylic acid, tridecanedicarboxylic acid, tetradecanedicarboxylic acid, pentadecanedicarboxylic acid, hexadecanedicarboxylic acid, heptadecanedicarboxylic acid, octadecanedicarboxylic acid, etc. Preferably adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, nonamethylene dicarboxylic acid, decamethylene dicarboxylic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, tridecanedicarboxylic acid, tetradecane Carboxylic acid, penta decane dicarboxylic acid, hexamethylene decanedicarboxylic acid, hepta-decane dicarboxylic acid, octadecane dicarboxylic acid, or the like is used. Of these, azelaic acid and sebacic acid are preferred.

  Examples of the carboxylic acid monoamide include those obtained by amidating one carboxyl group of the dicarboxylic acid. Preferable examples include those in which one carboxyl group of azelaic acid or sebacic acid is amidated.

  Examples of amines to be amidated include aliphatic primary amines such as butylamine, amylamine, hexylamine, heptylamine, octylamine, nonylamine, decylamine, laurylamine, myristylamine, palmitylamine, stearylamine, and behenylamine. Aliphatic secondary amines such as dipropylamine, diisopropylamine, dibutylamine, diamylamine, dilaurylamine, monomethyllaurylamine, distearylamine, monomethylstearylamine, dimyristylamine, dipalmitylamine, allylamine, diallylamine, oleylamine Aliphatic unsaturated amines such as dioleylamine, cycloaliphatic amines such as cyclopropylamine, cyclobutylamine, cyclopentylamine, cyclohexylamine, Aromatic amines such as dimethylamine, methylaniline, ethylaniline, benzylamine, dibenzylamine, diphenylamine, α-naphthylamine, etc., preferably hexylamine, heptylamine, octylamine, nonylamine, decylamine, laurylamine, myristylamine Palmitylamine, stearylamine, behenylamine, dibutylamine, diamylamine, monomethyllaurylamine, monomethylstearylamine, oleylamine and the like are used.

  In blending these soap-based thickeners, carboxylic acid and / or an ester thereof and the metal hydroxide may be added to the base oil and saponified in the base oil.

  When an alkali metal composite soap is prepared by saponification reaction in a base oil, for example, a combination of stearic acid and / or 12-hydroxystearic acid with azelaic acid or sebacic acid is used as the carboxylic acid. Is preferred.

  When preparing an alkaline earth metal composite soap by saponification reaction in a base oil, it is preferable to use, for example, a combination of sebacic acid and sebacic acid monostearylamide as carboxylic acid.

  In the saponification reaction in the base oil, a plurality of carboxylic acids and / or esters or acid amides thereof may be saponified simultaneously or sequentially.

  When the thickener is an alkali metal soap and / or an alkali metal composite soap, the blending amount is preferably 2 to 8% by mass in total. If the blending amount is less than 2% by mass, the degree of oil separation may be increased, and if it exceeds 8% by mass, the torque stability under durability conditions may be decreased.

  When the thickener is an alkaline earth metal composite soap, the blending amount is preferably 15 to 25% by mass. When the blending amount is less than 15% by mass, the degree of oil separation increases, and when it exceeds 25% by mass, the torque stability under the durability condition may be lowered.

Other Additives In the grease composition of the present invention, various known additives can be added as necessary in addition to the above-described components. Representative examples of additives include antioxidants and rust inhibitors.

  As the antioxidant, a phenolic antioxidant is suitable. Examples of the phenolic antioxidant include pentaerythritol tetrakis [3- (3,5-ditert-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-ditert-butyl-4-hydroxy). Phenyl) propionate, 1,3,5-trimethyl-2,4,6-tris (3,5-ditert-butyl-4-hydroxybenzyl) benzene, ethylenebis (oxyethylene) bis [3- (5-tert. 3-butyl-4-hydroxy-m-tolyl) propionate], hexamethylenebis [3- (3,5-ditert-butyl-4-hydroxyphenyl) propionate], 2,6-ditert-butyl-4-methyl Phenol, 2,2′-methylene bis (4-methyl-6-tert-butylphenol), 4,4′-butylidene bis (3-methyl-6) -Tert-butylphenol), 3,9-bis [2- (3- (3-tert-butyl-4-hydroxy-5-methylphenyl) -propionyloxy) -1,1-dimethylethyl] -2,4 , 8,10-tetraoxaspiro (5,5) undecane, 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, reaction product of p-cresol and dicyclopentadiene Etc. are used.

  The blending amount of the antioxidant is preferably in the range of 0.1 to 10% by mass with respect to the total amount of the grease composition in order to obtain a sufficient antioxidant effect.

  Although it does not restrict | limit especially as a rust preventive agent, A sarcosine derivative rust preventive agent can be used as a suitable thing. As the sarcosine derivative, for example, at least one of dialkyl (C8 to C12) diaminoethylglycine, alkyl (C12 to C18) dimethylbenzylglycine, alkylpolyaminoethylglycine, or a compound represented by the following general formula (i) may be used. Is possible.

Here, in the general formula (i), R ¹ is —R ³ or —C (═O) —R ³ (where R ³ is an alkyl having 1 to 30 carbon atoms (preferably 10 to 20). Represents a group, an alkenyl group or a hydroxyalkyl group), and R ² represents a hydrogen atom or an alkyl group or a hydroxyalkyl group having 3 to 6 carbon atoms.

  As a compounding quantity of a sarcosine derivative, in order to acquire sufficient rust prevention effect, it is preferable to use 0.1-10 mass% with respect to the composition whole quantity.

  In addition to these, generally known extreme pressure agents, corrosion inhibitors, viscosity index improvers and the like can be used according to the application of the grease composition.

  There is no restriction | limiting in particular about the preparation method of the grease composition based on this invention, Usually, the following method can be used.

  First, a predetermined proportion of thickener and, if desired, a thickener are blended into a part of the base oil, heated to a predetermined temperature, and homogenized by a known means such as a roll mill or a high-pressure homogenizer. Thereafter, the remaining base oil is blended and cooled, and when a predetermined temperature is reached, a predetermined amount of various additives are blended as desired, whereby the grease composition according to the present invention can be obtained.

  The grease composition of the present invention is a grease having excellent low-temperature characteristics and excellent torque stability under durable conditions. Such a grease composition of the present invention has a penetration (JIS K2220.7) in the range of 265 to 385 and an oil separation (JIS K2220.10) in the range of 0.8 to 5.0. It has excellent practical properties as a grease composition.

  The grease composition of the present invention includes various general-purpose plastics, engineering plastics such as polyamide, polyacetal, polycarbonate, polyethylene terephthalate, polybutylene terephthalate, polybutylene naphthalate, polyphenylene ether, polyphenylene sulfide, fluororesin, polyarylate, polyamideimide, Polyetherimide, polyetheretherketone, polysulfone, polyethersulfone, polyimide, polystyrene, polyethylene, polypropylene, phenol resin, AS resin, ABS resin, AES resin, AAS resin, ACS resin, MBS resin, polyvinyl chloride resin, Suitable for epoxy resin, diallyl phthalate resin, polyester resin, methacrylic resin, ABS / polycarbonate alloy, etc. It is.

  These resins form a molded product or a resin layer as various parts or members, and the grease composition according to the present invention is applied to a place where these resins come into contact with other resins or metals. Specifically, for example, sliding parts of automobile electrical components represented by electric power steering, door mirrors, etc., resin gears of acoustic equipment such as bearings, resin gears, radio cassettes, VTRs, CD players, and laser beam printers. Effectively applied to contact points between resin materials and other resin materials or metal materials that form resin gears of OA equipment such as printers, copiers and fax machines, various actuators for automobiles, sliding parts inside air cylinders, etc. Is done.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples.

(1) Preparation method of grease composition (1-1) Grease base oil containing Li soap (Thickener A) and lithium 12-hydroxystearate (Li-OHST manufactured by Katsuta Processing Co., Ltd.) And it mix | blended with the compounding quantity shown in Table 2, it cooled, after heating and stirring to melting temperature. Next, various additives were added to the formed gel material and stirred, and then the mixture was passed through a roll mill or a high-pressure homogenizer to prepare a grease containing Li soap.
(1-2) Grease containing Li complex soap (Thickener B) Base oil, 12-hydroxystearic acid and lithium hydroxide are mixed in a predetermined amount in a mixing and stirring vessel, and heated and stirred at about 80 to 130 ° C for saponification. Reaction was performed. Further, a predetermined amount of azelaic acid was blended and heated and stirred at about 80 to 200 ° C., lithium hydroxide was added thereto to form Li-Comp, and then cooled. Various additives were added to the formed gel substance and stirred, and then passed through a roll mill or a high-pressure homogenizer to prepare a grease containing Li composite soap.
(1-3) Grease containing Ba complex soap (Thickener C), base oil, sebacic acid and sebacic acid monostearyl amide are mixed in a predetermined amount in a mixing and stirring vessel, and heated and stirred at about 80 to 200 ° C. Barium hydroxide was added to form Ba-Comp, followed by cooling. Various additives were added to the formed gel substance and stirred, and then the mixture was passed through a roll mill or a high-pressure homogenizer to prepare a grease containing Ba composite soap.

(2) Measurement and evaluation method (2-1) Average molecular weight The average molecular weight was determined by gel permeation chromatography (GPC) using a polystyrene standard solution. The analysis conditions are as follows.
Pump: Hitachi L-6000 type detector: Hitachi L-3300 type RI detector Column: Gelpack GL-R440 + R450 + R400M
Sample concentration: 120 mg / 5 ml THF
Column size: 10.7mmφ × 300mm
Injection volume: 200 μl
Flow rate: 2.05 ml / min
Eluent: THF
(2-2) Base oil viscosity Base oil viscosity was measured based on JIS K2283.
(2-3) Mixing penetration and oil separation The mixing penetration and oil separation as general physical properties were measured according to JIS K2220.7 and JIS K2220.10, respectively.
(2-4) Durability After applying grease on the resin disk of the reciprocating test machine, pressing the resin cylinder from above and reciprocating for 7 hours, The friction coefficient was measured from the friction force generated between the resin disks.

Reciprocating tester Upper test piece: POM cylinder (φ15 × 22mm)
Lower test piece: POM disc Test load: 20N
Frequency: 20Hz
Amplitude: 2 mm (speed: 80 mm / s)
Test temperature: 25 ° C
Test time: 7 hours

(2-5) Low temperature performance The low temperature performance of the grease composition was evaluated with a rotational viscosity measuring machine. The test method was performed by applying grease on the plate and pressing and rotating the cone from above. The maximum torque (mNm) when the shear rate was increased to 5000 s ⁻¹ at −10 ° C. for 3 minutes was measured.

Rotational viscosity measuring machine Test jig: Cone (1 °) / plate Shear rate: 0-5000s ^-1
Test temperature: -10 ° C
Test time: 3min

(3) Evaluation results Tables 1 and 2 show the measurement results of the grease compositions of Examples and Comparative Examples (in the following table, the blending amounts are represented by weight ratios).

(Remarks)
Poly-α-olefin A: DURASYN 166 (40 ° C. kinematic viscosity 30 mm ² / s) manufactured by Ineos Oligomers Japan
Poly-α-olefin B: DURASYN 170 (40 ° C. kinematic viscosity 68 mm ² / s) manufactured by Ineos Oligomers Japan
Poly-α-olefin C: DURASYN 174 (40 ° C. kinematic viscosity 400 mm ² / s) manufactured by Ineos Oligomers Japan
Ethylene-α-olefin copolymer A: L6X-20 ((C ₂ H ₄ ·
C _n H _{2n) p,} the number average molecular weight 63,400, weight average molecular weight 109,900)
Ethylene-α-olefin copolymer B: Lucant HC-2000 ((C ₂ H ₄ · C ₃ H ₆ ) _n , number average molecular weight 7700, weight average molecular weight 14400) manufactured by Mitsui Chemicals, Inc.
Antioxidant: 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane Antirust agent: (Z) -N-methyl-N- (1-oxo-9-octadecenyl) )glycine

  As shown in Table 1, the grease composition according to the present invention has a low temperature torque within a range of 10 to 25, and has a good low temperature torque characteristic. Further, the friction coefficient is in the range of 0.08 to 0.13, and torque stability under durability conditions is realized.

Claims (5)

A grease composition comprising a base oil comprising a poly-α-olefin, an ethylene-α-olefin copolymer, and a thickener,
40 ° C. kinematic viscosity of the poly-α-olefin is in the range of 18 to 400 mm ² / s,
The number average molecular weight of the ethylene-α-olefin copolymer is in the range of 40,000 to 200,000, and the blending amount is in the range of 4 to 12% by mass with respect to the entire grease composition,
The base oil has a 40 ° C. kinematic viscosity in the range of 400 to 2500 mm ² / s,
The thickener is a total of 2 to 8% by weight of alkali metal soap and / or alkali metal composite soap based on the whole grease composition, or 15 to 25% by weight of alkaline earth based on the whole grease composition. metal-based composite soap der is,
A grease composition applied to a contact portion between a resin material and another resin material or a metal material .   The grease composition according to claim 1, wherein the thickener is 2 to 8% by mass of an alkali metal soap and / or an alkali metal composite soap based on the entire grease composition.   The grease composition according to claim 1 or 2, wherein the alkali metal is lithium.   The grease composition of claim 1, wherein the alkaline earth metal is barium.   The grease composition according to any one of claims 1 to 4, which has a penetration degree (JIS K2220.7) of 265 to 385.