JP2008115304A - Urea grease composition for resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a urea grease composition for a resin having excellent heat resistance, low torque property and resin abrasion resistance.
SOLUTION: At least one base oil selected from polyalphaolefins and silicone oils having a kinematic viscosity at 40 ° C. of 1 to 2000 mm ² / s, a specific urea-based thickener, 1 to 20% by mass, melting point 30 A urea grease composition for a resin used in a resin sliding portion, which contains 1 to 20% by mass of at least one lubricant selected from fatty acid amides at ˜120 ° C., oil-based waxes and polyolefin waxes.
[Selection figure] None

Description

  The present invention relates to a urea grease composition for a resin that can be applied to a lubricated portion of a resin sliding portion, is excellent in low torque property and heat resistance at high temperature, and is excellent in resin abrasion resistance.

  The grease composition applied to resin sliding parts such as bearings and gears using resin reacts with the metal surface even if an extreme pressure additive such as ZnDTP sulfur and phosphorus forming a lubricating film is added. For example, since a lubricating effect cannot be expected, a solid lubricant is usually blended. Polytetrafluoroethylene (hereinafter referred to as PTFE) powder is most frequently used as the solid lubricant used in such a grease composition for resin. Attempts have been made (see Patent Document 1, Patent Document 2, Patent Document 3, and Patent Document 4).

On the other hand, from the viewpoint of comfort and fuel efficiency, the device operates smoothly from a low temperature to a high temperature. Therefore, a reduction in resistance, that is, a low torque property is desired at the sliding portion.
As a thickener used for resin grease, a metal soap system such as lithium soap is usually used, but a urea system is often used when used at a high temperature. However, since this urea-based thickener has a property of becoming hard at high temperatures, resistance tends to increase and torque tends to increase.

In addition, although the sliding characteristics of the resin differ depending on the type, PTFE resin and high-density polyethylene resin (hereinafter referred to as high-density PE resin) are particularly excellent in low friction, so that the sliding intended for low friction is used. Used for moving parts. These resins have a mechanism showing a low friction property by taking a molecular orientation during friction and then peeling (wearing) the surface layer as small pieces. However, if the separated wear powder increases too much, the grease may harden and the original performance may not be sufficiently exhibited. Therefore, it is important to suppress the wear of the resin in a place where such a resin is used, and a grease composition for a resin excellent in the effect of suppressing the wear of the resin is desired.

Japanese Patent Laid-Open No. 4-91195 JP-A-9-194867 JP 2003-3185 A JP 2005-247971 A

  An object of the present invention is to provide a urea grease composition for a resin that is excellent in low torque property, heat resistance and wear resistance when applied to a resin sliding portion.

As a result of intensive studies in order to achieve the above-mentioned problems, the present inventors are selected from polyalphaolefins (hereinafter referred to as PAO) having a kinematic viscosity at 40 ° C. of 1 to 2000 mm ² / s and silicone oils. 1 to 20% by weight of at least one base oil and urea-based thickener, and 1 to 20 at least one lubricant selected from fatty acid amide, oil-based wax and polyolefin wax having a melting point of 30 to 120 ° C. It has been found that the inclusion of a mass% improves the low-torque property of urea-based grease at high temperatures and improves the wear resistance of the resin.

Moreover, it discovered that the abrasion resistance and heat resistance of resin were further improved by using saturated fatty acid amide or fat-type wax as said lubricant, and using silicone oil as a base oil. Further, the composition contains 2 to 40% by mass of at least one compound powder having a layered structure selected from mica, MCA (Melamine Cycnic Acid), and graphite. It has been found that the wear resistance and heat resistance of the resin are further improved by using an oil-based wax and using silicone oil as the base oil.

That is, the present invention provides at least one base oil selected from PAO having a kinematic viscosity at 40 ° C. of 1 to 2000 mm ² / s and a silicone oil, and a urea-based thickener represented by the general formula (1). A resin sliding part characterized by containing at least one lubricant selected from fatty acid amide having a melting point of 30 to 120 ° C., an oil-based wax and a polyolefin wax, and 1 to 20% by mass. The urea grease composition for resin used is provided.

（式中、ｙは０〜３の整数であり、Ｒ^１及びＲ^４は炭素数１〜３０の一価の炭化水素基であり、Ｒ^２及びＲ^３は炭素数１〜３０の二価の炭化水素基である。）
また、本発明は、上記樹脂用ウレアグリース組成物において、さらに、黒鉛、雲母及びＭＣＡ（Ｍｅｌａｍｉｎｅ Ｃｙａｎｕｒｉｃ Ａｃｉｄ）から選ばれる層状構造を持つ化合物粉末の少なくとも１種を２〜４０質量％含有する樹脂用ウレアグリース組成物を提供するものである。

(In the formula, y is an integer of 0 to 3, R ¹ and R ⁴ are monovalent hydrocarbon groups having 1 to 30 carbon atoms, and R ² and R ³ are divalent hydrocarbons having 1 to 30 carbon atoms. It is a hydrocarbon group.)
Further, the present invention provides the above urea grease composition for a resin, wherein the resin grease further contains 2 to 40% by mass of at least one compound powder having a layered structure selected from graphite, mica and MCA (Melamine Cycnic Acid). A urea grease composition is provided.

The present invention also provides the urea grease composition for resin, wherein the lubricant is a saturated fatty acid amide or an oily wax.
The present invention also provides a urea grease composition for resin, wherein the base oil is silicone oil.
The present invention also provides the urea grease composition for resin, wherein the resin sliding portion is a sliding portion using a polytetrafluoroethylene resin or a high-density polyethylene resin. Is.

  The urea grease composition for resin of the present invention is excellent in low torque property, heat resistance and wear resistance when applied to a resin sliding part. Therefore, the urea grease composition for resins of the present invention is extremely useful in practice.

The base oil used in the present invention is at least one selected from PAO and silicone oil.
PAO as a base oil is usually a low polymer of an α-olefin, and preferably an α-olefin decamer or less. The α-olefin is preferably an α-olefin having 6 to 18 carbon atoms. Particularly preferred PAOs are those containing a trimer or tetramer of α-decene having 10 carbon atoms or α-dodecene having 12 carbon atoms, and those dimers or pentamers or more. is there. As a suitable production example of PAO, there is a method of subjecting an α-olefin having 6 to 18 carbon atoms to low polymerization and a hydrogenation treatment.
As the silicone oil, dimethyl silicone or phenylmethyl silicone having an average molecular weight of 3000 to 15000 is preferably used.

The base oil used in the present invention preferably has a kinematic viscosity at 40 ° C. of 1 to 2000 mm ² / s, more preferably 5 to 1500 mm ² / s, and particularly preferably 10 to 1500 mm ² / s. If the kinematic viscosity is too small, the wear resistance 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.

In the present invention, at least one selected from PAO and silicone oil is an essential component, but other base oils can be appropriately blended within a range not impairing performance.
Specific examples include mineral oil base oils usually used for grease, synthetic lubricant base oils or mixtures thereof, and synthetic base oils include diesters, polyol esters, polyglycols, And phenyl ethers.

In the present invention, it is preferable to use PAO or silicone oil, but it is particularly preferable to use silicone oil from the viewpoint of heat resistance.
The content of the base oil can be appropriately selected according to the required characteristics, but is usually in the range of 55 to 98% by mass, preferably in the range of 59 to 95% by mass with respect to the total amount of grease. .

The urea grease composition for resins of the present invention contains at least one lubricant selected from fatty acid amides having a melting point of 30 to 120 ° C., oil-based waxes and polyolefin waxes. By blending these lubricants with urea grease, it is possible to suppress curing of the urea grease that occurs at high temperatures, to obtain low torque at high temperatures, and to obtain good wear resistance.
Examples of the fatty acid amide include unsaturated fatty acids having 14 to 24 carbon atoms and saturated fatty acids, but saturated fatty acid amides are preferred from the viewpoint of heat resistance. Specific examples of the fatty acid amide include palmitic acid amide, stearic acid amide, erucic acid amide and the like.

Examples of the oil-based wax include monoglycerides, diglycerides, and triglycerides having a fatty acid having 14 to 24 carbon atoms. Specific examples include stearic acid monoglyceride, stearic acid diglyceride, stearic acid triglyceride, and hardened castor oil.
Specific examples of the polyolefin wax include polyethylene wax, polypropylene wax, and a copolymer wax of ethylene and propylene.

In addition, melting | fusing point of these fatty acid amide, oil-based wax, and polyolefin wax is 30-120 degreeC, Preferably it is 40-120 degreeC, Most preferably, it is 50-110 degreeC. If the melting point is high, curing of the urea grease at a high temperature cannot be sufficiently suppressed, and it becomes difficult to obtain a sufficient low torque property at a high temperature. Moreover, even if the melting point is too low, a predetermined consistency cannot be obtained.
Moreover, the preferable content of these lubricants is 1 to 20% by mass, more preferably 3 to 18% by mass, and particularly preferably 4 to 15% by mass.
If the content of the lubricant is too small, the wear resistance of the resin tends to decrease. Even if it is too much, the effect tends to be saturated.
In the present invention, fatty acid amides and waxes are used as the lubricant. Among them, fatty acid amides and oil-based waxes are preferable from the viewpoint of the abrasion resistance of the resin.

In the present invention, the wear resistance can be further improved by blending at least one selected from compound powders having a layered structure selected from mica, MCA and graphite.
As mica, those represented by the following general formula (2) can be used.
A _l・ B _m・ C ₄・ O ₁₀・ D ₂ (2)
(In the formula, A is one or more selected from sodium atom, potassium atom, calcium atom, barium atom, rubidium atom and strontium atom, B is magnesium atom, iron atom, nickel atom, manganese atom, aluminum atom and lithium atom) One or more selected, C is one or more selected from silicon atom, germanium atom, aluminum atom, iron atom and boron atom, D is a hydroxyl group or fluorine atom, l is 0.5 to 1, m is 2 to 2 3)

Specific examples of mica include muscovite KAl ₂ (AlSi ₃ O ₁₀ ) (OH) ₂ , soda mica NaAl ₂ (AlSi ₃ O ₁₀ ) (OH) ₂ , phlogopite NaMg ₃ (AlSi ₃ O ₁₀ ) (OH) _2, and lepidolite _{KLiAl (Si 4 O 10) (} OH) 2 such as natural mica, fluorine phlogopite KMg ₃ a (OH) was replaced by _{F (AlSi 3 O 10) F} 2, tetrasilicic fluorine mica KMg _2. Fluorine mica such as ₅ (Si ₄ O ₁₀ ) F ₂ and teniolite KMg ₂ Li (Si ₄ O ₁₀ ) F ₂ can be used.

The MCA is a white fine powder composed of an adduct of melamine and cyanuric acid. The ratio of melamine and cyanuric acid in MCA is preferably 0.7: 1.3 to 1.3: 0.7 (molar ratio).
The graphite (graphite) is roughly classified into artificial graphite and natural graphite. Artificial graphite is produced by solidifying pitch coke with tar, pitch, etc., firing it at about 1200 ° C., and then processing it at a high temperature in a graphite furnace to grow carbon crystals. Natural graphite is graphitized over many years under natural geothermal and underground high pressure. Natural graphite is preferred as the graphite used in the present invention. Natural graphite includes scaly graphite, scaly graphite, and earthy graphite depending on the material used, and scaly graphite or scaly graphite is particularly preferable.

The average particle diameter of the mica, MCA, and graphite is preferably 0.1 to 25 μm, more preferably 2.1 to 20 μm, and particularly preferably 2.2 to 15 μm.
In particular, the average particle diameter of mica is preferably from 0.8 to 25 μm, particularly preferably from 2.1 to 20 μm. The average particle size of MCA is preferably 0.1 to 3 μm, particularly preferably 0.5 to 3 μm. Moreover, 1-15 micrometers is preferable and, as for the average particle diameter of graphite, 2.1-10 micrometers is especially preferable. In particular, the average particle size of flake graphite and scaly graphite is preferably 2.1 to 10 μm, and particularly preferably 2.1 to 8 μm.

The content of mica, MCA and graphite is the total amount of these, and the lower limit is 2% by mass or more, preferably 3% by mass or more, more preferably 5% by mass or more, Preferably it is 7 mass% or more, Most preferably, it is 8 mass% or more. The upper limit of the content of the compound powder having a layered structure is 40% by mass or less, preferably 25% by mass or less, and particularly preferably 20% by mass or less. By setting it as the above content, the wear resistance can be further improved. In addition, even if it mix | blends the quantity exceeding the upper limit of the said content, there exists a tendency for an effect to be saturated.

The thickener used in the urea grease composition for resins of the present invention is urea.
Examples of the urea include those represented by the following general formula (1).

(In the formula, y is an integer of 0 to 3, R ¹ and R ⁴ are monovalent hydrocarbon groups having 1 to 30 carbon atoms, and R ² and R ³ are divalent hydrocarbons having 1 to 30 carbon atoms. It is a hydrocarbon group.)
In General formula (1), y is an integer of 0-3, Preferably it is 0 or 1, More preferably, it is 0. R ¹ and R ⁴ are each a monovalent hydrocarbon group having 1 to 30 carbon atoms, and examples of the hydrocarbon group include an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, an aromatic hydrocarbon group, or a combination thereof. And the hydrocarbon group has 1 to 30 carbon atoms, preferably 3 to 22 carbon atoms, more preferably 6 to 18 carbon atoms. R ² and R ³ are divalent hydrocarbon groups having 1 to 30 carbon atoms, and examples of the hydrocarbon group include an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, an aromatic hydrocarbon group, or a combination thereof. Can be mentioned. Carbon number of a hydrocarbon group is 1-30, Preferably it is 3-22, More preferably, it is 6-18.
The polyurea of the general formula (1) is usually obtained by the reaction of diamine and diisocyanate.

Here, those in which R ¹ and R ⁴ are aliphatic hydrocarbon groups are referred to as aliphatic polyurea compounds, and those in which R ¹ and R ⁴ are alicyclic hydrocarbon groups are referred to as alicyclic polyurea compounds, and R ¹ , R ⁴ is an aromatic hydrocarbon group is called an aromatic polyurea compound.
The above thickeners can be used alone or in combination of two or more.
The thickener used in the urea grease composition for resins of the present invention imparts consistency to the present invention, and the preferred content is 1 to 20% by mass, more preferably 2 to 20% by mass. When the content is too small, the grease does not become a grease and a predetermined consistency is not obtained. On the other hand, if the amount is too large, the low torque property tends to decrease.

Moreover, although the urea grease composition for resin of this invention mix | blends the base oil of each said component, and a thickener, various additives can be mix | blended suitably as needed.
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, phosphorus, amine, ester, and other antiwear agents; polymethacrylate, ethylene propylene copolymer, styrene-isoprene copolymer, styrene-isoprene copolymer Various viscosity index improvers such as hydride or polyisobutylene; alkylphenols such as 2,6-di-tert-butyl-p-cresol, 4,4′-methylenebis- (2,6-di-t-butylphenol), etc. Bisphenols, n-octadecyl-3- (4′-hydroxy) 3 ′, 5′-di-tert-butylphenol) propionate and other antioxidants such as phenolic compounds, aromatic amine compounds such as naphthylamines and dialkyldiphenylamines; sulfurized olefins, sulfurized fats and oils, methyltrichlorostearate, Extreme pressure agent such as chlorinated naphthalene, benzyl iodide, fluoroalkylpolysiloxane, lead naphthenate, carboxylic acid such as stearic acid, dicarboxylic acid, metal soap, carboxylic acid amine salt, metal salt of heavy sulfonic acid, polyvalent Examples include various rust inhibitors such as carboxylic acid partial esters of alcohol; various corrosion inhibitors such as benzotriazole and benzimidazole.

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 1-7 and Comparative Examples 1-5)
In Examples and Comparative Examples, grease compositions containing the following * 1 to * 18 components in the proportions (mass) shown in Tables 1 and 2 were prepared. The thickener of * 1 to * 18 is obtained 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 * 18 A grease composition containing these components was prepared. The grease composition was prepared by appropriately mixing the components * 1 to * 18 and milling to uniformly disperse the thickener in the grease.
Each of the obtained grease compositions was evaluated for abrasion resistance of the resin.

* 1: Aliphatic diurea (Introducing each base oil and diphenylmethane-4,4-diisocyanate into a heat-resistant container, heating, then adding octylamine at about 60 ° C. and reacting for about 40 minutes. Then, the mixture was heated to 170 ° C. with stirring, cooled with base oil, and milled to optimize diurea crystals, and a grease mixed and dispersed in the base oil was prepared.
(In general formula (1), y is 0, R ¹ and R ⁴ are monovalent aliphatic hydrocarbon groups having 8 carbon atoms, and R ² is a divalent aromatic hydrocarbon group having 13 carbon atoms. .)

* 2: Alicyclic diurea (The base oils listed in the table and diphenylmethane-4,4-diisocyanate are added to a heat-resistant container, heated, and then cyclohexylamine is added at about 60 ° C. for about 40 minutes. Then, the mixture was heated to 110 ° C. with stirring, cooled with base oil, and milled to optimize diurea crystals, and a grease mixed and dispersed in the base oil was prepared.
(In general formula (1), y is 0, R ¹ and R ⁴ are monovalent alicyclic hydrocarbon groups having 6 carbon atoms, and R ² is a divalent aromatic hydrocarbon having 13 carbon atoms. Group.)

* 3: Lithium-12-hydroxystearate (each base oil in the table and lithium-12-hydroxystearate (manufactured by Sakai Chemicals; trade name: S7000H) are charged into a heat-resistant container and heated, and at about 200 ° C It was dissolved, cooled with base oil, milled to optimize lithium-12-hydroxystearate crystals, and a grease mixed and dispersed in the base oil was prepared.)

* 4: Lithium stearate (each base oil in the table and lithium stearate (manufactured by Sakai Chemical; product name: S7000) are put into a heat-resistant container and heated, dissolved at about 200 ° C. Cooling and milling were performed to optimize lithium-stearate crystals, and a grease mixed and dispersed in the base oil was prepared.

* 5: Mineral oil base oil (40 ° C kinematic viscosity: 100 mm ² / s hydrorefined mineral base oil)
* 6: PAO (kinematic viscosity at 40 ° C .: polyalphaolefin of 60 mm ² / s)
* 7: Silicone oil (40 ° C. kinematic viscosity: 380 mm ² / s dimethyl silicone)
* 8: Stearic acid amide (melting point: 102 ° C)
* 9: Ethylene bis stearic acid amide (melting point 145 ° C)
* 10: Polyethylene wax A (melting point 98 ° C.)
* 11: Polyethylene wax B (melting point: 136 ° C.)
* 12: Hardened castor oil (melting point 85 ° C)

* 13: Stearic acid monoglyceride (melting point: 68 ° C)
* 14: Scale-like graphite having an average particle diameter of 5 μm * 15: MCA (manufactured by Mitsubishi Chemical Corporation: MCA), average particle diameter of 1 μm
* 16: Mica (manufactured by Corp Chemical Co .: Micromica SIMK <Fluorine Mica>), average particle size 2.5 μm
* 17: PTFE (Daikin: Lubron)
* 18: Antioxidant (diphenylamine)

(Measuring method)
(1) Temperature-consistency characteristics The consistency of normal temperature (25 ° C) was measured in accordance with JIS K2220.
In addition, at a high temperature consistency (120 ° C.), the consistency at 120 ° C. was measured by a test method specified in ISO 13737.
Evaluation was performed by the difference between the normal temperature consistency and the high temperature consistency (high temperature consistency−normal temperature consistency). When the value of the high temperature consistency-normal temperature consistency is negative, it indicates a tendency to become hard at high temperatures. That is, the low torque property under high temperature is inferior.

(2) Resin abrasion resistance test A Falex type friction tester was used. In the test, 0.5 g of grease was applied to the sliding portion using a steel pin and a PTFE resin block, and the test was performed for 5 minutes with a tightening load of 50 N under a pin rotation speed of 500 rpm and temperature. Next, the main operation was performed at 100 N for 55 minutes. Evaluation was made by measuring the weight loss (wear amount) of the block before and after the test. The smaller the amount of wear, the better the wear resistance.

(3) Heat resistance A thin film heating test was performed. In this test, grease was uniformly applied to the steel plate to a thickness of 2 mm and left in a thermostatic bath at 150 ° C. for 96 hours. The evaluation was performed based on the following criteria by measuring the total acid value before and after the test and depending on the degree of increase in the total acid value.
A: The total acid value increase is less than 1.0 mgKOH / g.
○: Total acid value increase is 1.0 mgKOH / g or more and less than 4.0 mgKOH / g.
(Triangle | delta): The total acid value increase is 4.0 mgKOH / g or more and less than 6.0 mgKOH / g.
X: Total acid value increase is 6.0 mgKOH / g or more.

  The urea grease composition for resin of the present invention can be applied to various resin sliding parts, but can be suitably applied to lubricated portions of the resin sliding parts in automobiles, home appliances, OA equipment and the like.

Claims (5)

1 to 20% by mass of at least one base oil selected from a polyalphaolefin having a kinematic viscosity at 40 ° C. of 1 to 2000 mm ² / s and a silicone oil, and a urea thickener represented by the general formula (1) And a resin used in a resin sliding part, which contains 1 to 20% by mass of at least one lubricant selected from fatty acid amides having a melting point of 30 to 120 ° C., oil-based waxes and polyolefin waxes Urea grease composition.

(In the formula, y is an integer of 0 to 3, R ¹ and R ⁴ are monovalent hydrocarbon groups having 1 to 30 carbon atoms, and R ² and R ³ are divalent hydrocarbons having 1 to 30 carbon atoms. It is a hydrocarbon group.)   The urea grease composition for resin according to claim 1, further comprising 2 to 40% by mass of at least one compound powder having a layered structure selected from mica, MCA (Melamine Cycnic Acid) and graphite.   The urea grease composition for resin according to claim 1 or 2, wherein the lubricant is a saturated fatty acid amide or an oil-based wax. The urea grease composition for resin according to any one of claims 1 to 3, wherein the base oil is a silicone oil. The urea grease composition for resin according to any one of claims 1 to 4, wherein the resin sliding portion is a sliding portion using a polytetrafluoroethylene resin or a high-density polyethylene resin.