JP2008239847A - Flame-retardant grease composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grease composition excellent in flame retardancy, self-extinguishing property and storage stability. <P>SOLUTION: The grease composition comprises a base oil containing at least 10 mass% relative to the total base oil of a phosphor-containing compound having a kinematic viscosity of 1-2,000 mm<SP>2</SP>/s at 40°C, and a composite lithium soap, as a thickener, comprising (A) a lithium salt of a 12-24C hydroxyfatty acid and (B) a phosphoric acid compound lithium salt. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a grease composition excellent in fire resistance and storage stability that can be applied to lubricated parts of industrial machines and the like.

  In recent years, as machine technology has been developed more and more, equipment has been operated under high speed, high temperature and high load conditions. Therefore, it is necessary to assume that the grease used for such a part is softened due to deterioration or mixing of foreign matters, and dripping down to a high temperature part. In some cases, a grease filling operation is performed on a rolling bearing, a sliding bearing, a gear driving unit, or the like under severe conditions such as a fire source. Therefore, it is desired that the grease used for such a place having a fire risk is more flame retardant and does not continuously burn even if ignited, that is, has excellent self-extinguishing properties.

Conventionally, grease compositions used in such locations have used grease containing lithium soap, urea, etc. based on mineral oil, so that these flame retardants and self-extinguishing properties can be improved. Furthermore, attempts have been made to add additives (see Patent Document 1), thickeners and base oil compositions (see Patent Document 2), and the like.
In addition, it is desirable that such grease has excellent storage stability as the basic performance of the grease.

JP-A-8-199183 JP 2004-67843 A

  The present invention provides a grease composition that can be used in various applications where ignition is possible, has excellent flame retardancy and self-extinguishing properties, and is excellent in storage stability.

As a result of intensive studies to achieve the above object, the present inventors use a phosphorus-containing compound as a base oil, and (A) a lithium salt of a hydroxy fatty acid having 12 to 24 carbon atoms as a thickener and (B) It has been found that by using a complex lithium soap-based thickener composed of a phosphoric acid compound lithium salt, it is excellent in flame retardancy, self-extinguishing property and storage stability. Among them, it has been found that flame retardancy and self-extinguishing properties are remarkably improved by using a phosphorus-containing compound represented by the formula (1) as a base oil.

That is, the present invention contains a phosphorus-containing compound having a kinematic viscosity at 40 ° C. of 1 to 2000 mm ² / s as a base oil in an amount of 10% by mass or more based on the total amount of base oil, and (A) a carbon number of 12 to The present invention provides a grease composition comprising a composite lithium soap composed of 24 lithium salt of hydroxy fatty acid and (B) lithium salt of phosphoric acid compound.
Moreover, this invention provides the grease composition whose phosphorus-containing compound as a base oil is the phosphoric acid compound represented by Formula (1) in the said grease composition.

(R ¹ O) (R ² O) (R ³ O) P (O) _a (1)
(Wherein R ¹ , R ² and R ³ are a hydrogen atom or a hydrocarbon group having 1 to 24 carbon atoms, which may be the same or different, and a is an integer of 0 or 1. is there.)
In the above grease composition, R ¹ , R ² and R ³ in the formula (1) are hydrocarbon groups having 1 to 24 carbon atoms, which may be the same or different. Often, a grease composition in which a is 1 is provided.

  The grease composition of the present invention is excellent in flame retardancy, self-extinguishing property and storage stability.

The components contained in the grease composition of the present invention will be described below.
(1) Base oil In the grease composition of the present invention, the phosphorus-containing compound used as the base oil has a kinematic viscosity at 40 ° C. of 1 to 2000 mm ² / s, preferably ² to 1000 mm ² / s, particularly preferably. Is 5 to 600 mm ² / s. If the kinematic viscosity is too small, the flame retardancy and self-extinguishing properties tend to be low. If the kinematic viscosity is too large, the fluidity is deteriorated and the inherent performance of the grease tends to be difficult.

Examples of phosphorus-containing compounds used as base oils include phosphoric acid compounds such as thiophosphoric acid esters, dithiophosphoric acid esters, acidic phosphoric acid esters, acidic phosphoric acid ester metal salts, phosphoric acid esters, and phosphorous acid esters. Can be mentioned.
Among these, as a phosphorus containing compound used as a base oil in the grease composition of the present invention, a phosphoric acid compound represented by the formula (1) is preferable.

(R ¹ O) (R ² O) (R ³ O) P (O) _a (1)
(Wherein R ¹ , R ² and R ³ are a hydrogen atom or a hydrocarbon group having 1 to 24 carbon atoms, which may be the same or different, and a is an integer of 0 or 1. is there.)
In the formula ^{(1), R 1, R} 2 and ^{R 3} are a hydrogen atom or a hydrocarbon group having 1 to 24 carbon atoms. When R ¹ , R ² and R ³ are all hydrogen atoms, there is a possibility of corroding the steel member. Therefore, at least one of R ¹ , R ² and R ³ must be a hydrocarbon group. Are preferable, and it is more preferable that all of R ¹ , R ² and R ³ are hydrocarbon groups.

If the hydrocarbon group has too many carbon atoms, the fluidity of the base oil tends to decrease. Carbon number of a C1-C24 hydrocarbon group becomes like this. Preferably it is 1-18, More preferably, it is 2-15, Most preferably, it is 3-12. The total amount of carbon atoms of R ¹ , R ² and R ³ is preferably 4 to 45, more preferably 6 to 40, and particularly preferably 8 to 35.
The hydrocarbon group may be an aromatic hydrocarbon group, an alicyclic hydrocarbon group or an aliphatic hydrocarbon group, but preferably an aliphatic hydrocarbon group, an aromatic hydrocarbon group, or a combination thereof. More preferred is an aromatic hydrocarbon group or a combination of an aliphatic hydrocarbon group and an aromatic hydrocarbon group, and particularly preferred is an aromatic hydrocarbon group.

The aliphatic hydrocarbon group may be linear or branched. Specific examples of the aliphatic hydrocarbon group include an ethyl group, a propyl group, a butyl group, an octyl group, an isodecyl group, a dodecyl group, a tridecyl group, a stearyl group, and an oleyl group. Specific examples of the aromatic hydrocarbon group include a phenyl group, a cresyl group, a xylyl group, an ethylphenyl group, an isopropylphenyl group, a butylphenyl group, and an octylphenyl group.
Moreover, although a in the formula (1) is an integer of 0 or 1, the case where a is an integer of 1 is more excellent in fire resistance.
The phosphorus-containing compound as the base oil does not include a phosphorus-containing compound as a thickener described later.

  The grease composition of the present invention may contain other base oil in the phosphorus-containing compound as a base oil. In the grease composition of the present invention, the content of the phosphorus-containing compound as the base oil is 10% by mass or more, preferably 12% by mass or more, more preferably 15% by mass with respect to the total base oil amount. Or more, more preferably 35% by mass or more, and particularly preferably 50% by mass or more. If the amount of phosphorus-containing compound is too small, self-extinguishing properties cannot be obtained.

Other base oils used in combination with the phosphorus-containing compound include various lubricating oils such as mineral lubricating base oils, synthetic lubricating base oils, or mixed lubricating base oils usually used for grease. Oil base oil is used. Other base oil, the value of kinematic viscosity at 40 ° C. is preferably 1~2000mm ² / s, more preferably 2~1000mm ² / s, particularly preferably 5~600mm ² / s. If the kinematic viscosity is too small, the self-extinguishing property tends to be low. If the kinematic viscosity is too large, the fluidity is deteriorated and the inherent performance of the grease tends to be difficult.

Examples of the mineral oil base oil include a mineral oil base oil obtained by refining a lubricating oil fraction of crude oil by appropriately combining solvent refining, hydrorefining, and the like.
Synthetic lubricant base oils include carbons such as α-olefin oligomers, polymers of α-olefins having 3 to 12 carbon atoms, sebacates such as 2-ethylhexyl sebacate, dioctyl sebacate, azelate, and adipate. Dialkyl diesters having 4 to 12 carbon atoms, 1-trimethylolpropane, polyols including esters obtained from pentaerythritol and monobasic acids having 3 to 12 carbon atoms, alkylbenzenes having an alkyl group having 9 to 40 carbon atoms Polyglycols such as polyglycol obtained by condensing butyl alcohol with propylene oxide, phenyl ethers such as polyphenyl ether having about 2 to 5 ether chains and about 3 to 6 phenyl groups, etc. Can be mentioned.

The mineral oil base oil and the synthetic base oil can be used alone or in combination of two or more.
The amount of the base oil can be appropriately selected according to the required characteristics, but is usually in the range of 60 to 98% by mass, preferably 80, based on the total amount of the grease composition composed of the base oil and the thickener. It is the range of -95 mass%.

(2) Thickener The thickener used in the grease composition of the present invention is a composite lithium soap comprising (A) a lithium salt of a hydroxy fatty acid having 12 to 24 carbon atoms and (B) a lithium salt of a phosphoric acid compound. It is.
By combining this thickener with a base oil comprising a phosphorus-containing compound, a sufficient self-extinguishing effect can be obtained. In addition, when phosphorus-containing compounds are used in grease base oils, storage stability may deteriorate due to significant changes in the consistency of grease during storage. However, if this thickener is used, phosphorus-containing compounds It is possible to improve the storage stability of the grease using as a base oil.

The lithium salt of a hydroxy fatty acid having 12 to 24 carbon atoms as the component (A) constituting the thickener is a lithium salt of a saturated or unsaturated aliphatic monocarboxylic acid having a straight chain or a branched chain. Lithium acid salt is preferred, and lithium 12-hydroxystearate is particularly preferred.
A lithium salt of a hydroxy fatty acid having 12 to 24 carbon atoms can be obtained by reacting a hydroxy fatty acid having 12 to 24 carbon atoms with lithium hydroxide. The hydroxy fatty acid having 12 to 24 carbon atoms is a linear or branched aliphatic monocarboxylic acid. Specific examples thereof include 2-hydroxytetradecanoic acid, 2-hydroxyhexadecanoic acid, 11-hydroxyhexadecanoic acid, ricinoleic acid, 9 -Hydroxystearic acid, 10-hydroxystearic acid, 12-hydroxystearic acid and the like. Of these, hydroxystearic acid is preferable, and 12-hydroxystearic acid is particularly preferably used.
(A) A component may be used by 1 type and may be used in combination of 2 or more type.

As the phosphoric acid compound lithium salt of the component (B) constituting the thickener, various lithium acid compound lithium salts can be used, but lithium phosphate salt, lithium phosphite salt or a mixture thereof is preferably mentioned. .
The component (B) component lithium phosphate salt, lithium phosphite salt or a mixture thereof is phosphoric acid, phosphorous acid, phosphoric acid ester, acidic phosphoric acid ester, phosphorous acid ester, etc. represented by the following formula (2) It can obtain by making phosphoric acid compound of this and lithium hydroxide react.

(R ⁴ O) (R ⁵ O) (R ⁶ O) P (O) _b (2)
(Wherein R ⁴ , R ⁵ and R ⁶ are a hydrogen atom or a hydrocarbon group having 1 to 24 carbon atoms, which may be the same or different, and b is an integer of 0 or 1) is there.)
In the formula, R ⁴ , R ⁵ and R ⁶ are a hydrogen atom or a hydrocarbon group having 1 to 24 carbon atoms, preferably a hydrogen atom or a hydrocarbon group having 1 to 8 carbon atoms, more preferably a hydrogen atom or carbon. A hydrocarbon group having 1 to 6 carbon atoms, particularly preferably a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms, and at least one of R ⁴ , R ⁵ and R ⁶ has 1 to 6 carbon atoms. It is a hydrocarbon group.

The hydrocarbon group may be an aromatic hydrocarbon group, an alicyclic hydrocarbon group, or an aliphatic hydrocarbon group, but is preferably an aliphatic hydrocarbon group.
When R ⁴ , R ⁵ or R ⁶ is a hydrocarbon group, the carbon number is preferably smaller, for the following reason.

When the above ester is used to produce a lithium phosphate salt, a lithium phosphite salt, or a mixture thereof, alkyl alcohol or allyl alcohol is produced as a by-product by reaction with lithium hydroxide. If such alcohol remains in the grease, the self-extinguishing property tends to deteriorate, so that it is necessary to remove these alcohols. These alcohols can be removed by various methods, but evaporative removal is preferred because of its simple operation. Therefore, it is preferable to use a phosphoric acid ester compound having a small number of carbon atoms of R ⁴ , R ⁵ or R ⁶ from the viewpoint of evaporative removal.
In addition, by making at least one of R ⁴ , R ⁵ and R ⁶ a hydrocarbon group, it is possible to make it easier to produce a composite lithium soap. From this viewpoint, it is more preferable that all of R ⁴ , R ⁵ and R ⁶ are hydrocarbon groups.
Further, b in the formula is an integer of 0 or 1, with 0 being particularly preferred.
(B) A component may be used by 1 type and may be used in combination of 2 or more type.

The blending amount of the composite lithium soap, which is a thickener used in the grease composition of the present invention, is preferably 3 to 40% by mass, more preferably 5 to 20% by mass. If the blending amount is too small, the grease does not become a grease and there is a tendency that an appropriate consistency is not obtained, and if it is too large, the lubricity of the product grease tends to be lowered. In addition, (A) a lithium salt of a hydroxy fatty acid having 12 to 24 carbon atoms and (B) a lithium salt of a complex of a phosphoric acid compound, but from the viewpoint of further improving self-extinguishing properties and storage stability, The ratio of component A) to component (B) is preferably 3: 1 to 3: 5 in molar ratio.

(3) Other components The grease composition of the present invention contains the base oil of each of the above components and a thickener, and various additives can be appropriately added as necessary.
Examples of additives include metal-based detergents such as alkaline earth metal sulfonates, alkaline earth metal phenates, alkaline earth metal salicylates; alkenyl succinimides, alkenyl succinimide boronated modified products, benzylamine, alkylpolyamines Dispersants such as zinc, sulfur, amine, ester, etc .; polymethacrylate, ethylene propylene copolymer, styrene-isoprene copolymer, hydrogenated styrene-isoprene copolymer or Various viscosity index improvers such as polyisobutylene; alkylphenols such as 2,6-di-tert-butyl-p-cresol, bisphenols such as 4,4′-methylenebis- (2,6-di-t-butylphenol) N-octadecyl-3- (4′-hydroxy-3 ′, Various antioxidants such as phenolic compounds such as' -di-tert-butylphenol) propionate, aromatic amine compounds such as naphthylamines and dialkyldiphenylamines; sulfurized olefins, sulfurized fats and oils, methyltrichlorostearate, chlorinated naphthalene, iodine Benzyl fluoride, fluoroalkylpolysiloxane, extreme pressure agent such as lead naphthenate, carboxylic acid such as stearic acid, dicarboxylic acid, metal soap, carboxylic acid amine salt, metal salt of heavy sulfonic acid, carboxylic acid part of polyhydric alcohol Examples include various rust inhibitors such as esters; various corrosion inhibitors such as benzotriazole and benzimidazole, and various antifoaming agents such as silicone oil. An additive can be used individually by 1 type or in combination of 2 or more types.

  Next, the present invention will be specifically described with reference to examples. In addition, this invention is not limited at all by these Examples.

(Examples 1-8 and Comparative Examples 1-6)
In Examples and Comparative Examples, grease compositions were prepared containing the components * 1 to * 12 shown below in the proportions (parts by mass) shown in Tables 1 and 2. Thickeners among * 1 to * 12 are prepared by mixing the raw material of the thickener with the base oil and reacting the raw material in the base oil to obtain a thickener. As a result, * 1 to * 12 A grease composition containing these components was prepared. The grease composition was prepared by appropriately mixing the components * 1 to * 12 and milling to uniformly disperse the thickener in the grease composition.
The obtained grease composition was evaluated in a flammability test and a storage stability test, respectively.

* 1: Composite lithium soap A
Paraffinic mineral oil, 12-hydroxystearic acid and tributyl phosphite in a heat-resistant container (in formula (2), R ⁴ , R ⁵ and R ⁶ are hydrocarbon groups having 4 carbon atoms, and b is an integer of 0. ) And heat. Next, an aqueous lithium hydroxide solution is added at about 80 ° C. and sufficiently reacted to form 12-hydroxystearic acid lithium salt and phosphorous acid trilithium salt. Then, it heats to about 230 degreeC vicinity and evaporates and removes butyl alcohol. Then, by performing rapid cooling after semi-melting, the lithium complex soap crystal is optimized, and the composite lithium soap composed of 12-hydroxystearic acid lithium salt and trilithium phosphite salt is uniformly in the base oil. A grease composition prepared by mixing and dispersing was prepared.

* 2: Composite lithium soap B
Each base oil and 12-hydroxystearic acid in the table are put into a heat-resistant container and heated. Next, an aqueous lithium hydroxide solution is added at about 80 ° C., and lithium 12-hydroxystearate is produced by a saponification reaction. Further, lithium hydroxide and azelaic acid are added at about 90 ° C. and reacted for about 2 hours to produce composite lithium soap. Thereafter, this is heated, semi-molten, and then rapidly cooled to optimize the crystal of the composite lithium soap, and based on the composite lithium soap comprising 12-hydroxystearic acid lithium salt and azelaic acid lithium salt. A grease composition was prepared by uniformly mixing and dispersing in oil.

* 3: Each 12-hydroxystearic acid salt and 12-hydroxystearic acid lithium salt (manufactured by Sakai Chemicals; trade name “S7000H”) are put in a heat-resistant container of 12: 12-hydroxystearic acid salt and heated at about 200 ° C. Dissolved, added base oil, cooled and milled to optimize the crystals of 12-hydroxystearic acid lithium salt and prepare a grease mixed and dispersed in the base oil.

* 4: Each base oil and diphenylmethane-4,4-diisocyanate in the table are put into an aliphatic diurea heat-resistant container, heated, and then octylamine is added at about 60 ° C. and reacted for about 40 minutes. Thereafter, the mixture was heated to 170 ° C. with stirring, the base oil was added, and after cooling, milling was performed to optimize diurea crystals, and a grease composition mixed and dispersed in the base oil was prepared.

* 5: Phosphorus-containing compound 1: Cresyl diphenyl phosphate In formula (1), a = 1, R ¹ is a cresyl group, and R ² and R ³ are phenyl groups. The kinematic viscosity at 40 ° C. is 40 mm ² / s.
* 6: Phosphorus-containing compound 2: tricresyl phosphate In formula (1), a = 1 and all of R ^{1 to} R ³ are cresyl groups. The kinematic viscosity at 40 ° C. is 22 mm ² / s.
* 7: Phosphorus-containing compound 3: trixylyl phosphate In formula (1), a = 1 and all of R ^{1 to} R ³ are xylyl groups. The kinematic viscosity at 40 ° C. is 48 mm ² / s.
* 8: Phosphorus-containing compound 4: Phenyl isopropyl phosphate In formula (1), a = 1, R ^{1 to} R ³ are a mixture of a phenyl group and an isopropyl phenyl group. The kinematic viscosity at 40 ° C. is 42 mm ² / s.

* 9: Phosphorus-containing compound 5: butyl diphenyl phosphate In formula (1), a = 1, R ^{1 to} R ³ are a mixture of a butyl group and a phenyl group. The kinematic viscosity at 40 ° C. is 39 mm ² / s.
* 10: Hydrorefined mineral oil with mineral oil 40 ° C kinematic viscosity of 100 mm ² / s * 11: Synthetic oil 1
Polyalphaolefin having a kinematic viscosity at 40 ° C. of 60 mm ² / s * 12: Antioxidant (diphenylamine)

(Measuring method)
Flammability test 15 g of the grease composition was put in a cylindrical steel container having an inner diameter of 55 mm and a depth of 30 mm, a steel ball having a diameter of 19.05 mm heated to 950 ° C. was dropped and contacted with the grease composition, and whether or not ignition occurred. When ignited, the time until the end of combustion was measured. Evaluation was performed according to the following criteria.
A: Not ignited (nonflammable)
○: Ignites, but combustion is completed in less than 30 seconds (with self-extinguishing properties)
×: Ignites and continues to burn for 30 seconds or more (no self-extinguishing)

Storage Stability Test 20 g of grease was put in a beaker, placed in a thermostatic bath having a humidity of 95% and a temperature of 50 ° C., and allowed to stand for one week. The evaluation was made based on the difference in the mixing penetration before and after the test.
◎: Difference in immiscible consistency before and after test is less than 25 ○: Difference in immiscible consistency before and after test is 25 or more and less than 50 ×: Difference in immiscible consistency before and after test is 50 or more

  The grease composition of the present invention can be applied to lubricated locations such as various industrial machines, and in particular, can be applied to lubricated locations such as industrial machines that are operated under high speed, high temperature and high load conditions that require fire resistance. .

Claims (3)

10% by mass or more of a phosphorus-containing compound having a kinematic viscosity at 40 ° C. of 1 to 2000 mm ² / s as a base oil with respect to the total amount of the base oil,
A grease composition comprising (A) a lithium salt of a hydroxy fatty acid having 12 to 24 carbon atoms and (B) a composite lithium soap comprising a lithium salt of a phosphoric acid compound as a thickener. The grease composition according to claim 1, wherein the phosphorus-containing compound as the base oil is a phosphoric acid compound represented by the formula (1).
(R ¹ O) (R ² O) (R ³ O) P (O) _a (1)
(Wherein R ¹ , R ² and R ³ are a hydrogen atom or a hydrocarbon group having 1 to 24 carbon atoms, which may be the same or different, and a is an integer of 0 or 1. is there.) The R ¹ , R ² and R ³ in the formula (1) are hydrocarbon groups having 1 to 24 carbon atoms, which may be the same or different, and a is 1. 4. Grease composition.