JP2016210829A - Thickener, grease, manufacturing method of thickener and grease sealed shaft bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thickener capable of manufacturing grease excellent in high temperature high speed durability and a grease sealed shaft bearing with grease sealed therein.SOLUTION: In a thickener consisting of an aromatic diimide compound obtained by reacting 2 moles of an aromatic acid anhydride to 1 mole of aromatic diisocyanate in an ester oil, the aromatic diimide compound is represented by a peak in a differential curve of a thermogravimetric curve measured by a predetermined temperature rise rate in an inert atmosphere.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a novel thickener, a grease containing the thickener, a method for producing the same, and a grease-filled bearing in which the grease is sealed. In particular, the present invention relates to grease used by being sealed in a bearing used in high-temperature and high-speed rotation such as electrical equipment used in home appliances, industrial equipment, and automobile engine rooms, and the grease-filled bearing.

  Rolling bearings incorporated in various electrical accessories and industrial equipment are filled with grease to provide lubricity. This grease is obtained by kneading a base oil and a thickener and, if necessary, an additive. Synthetic lubricating oils such as mineral oil, ester oil, silicone oil, and ether oil are generally used as the base oil, and metal soaps and urea compounds such as lithium soap are generally used as the thickener. Moreover, as an additive, various additives, such as antioxidant, a rust inhibitor, a metal deactivator, a viscosity index improver, are mix | blended as needed.

Rolling bearings used in home appliances, industrial equipment motors, electrical accessory machines, etc. are used under high-temperature and high-speed rotation conditions as the performance of these equipment increases, so they have excellent high-temperature and high-speed durability. Is required. At the same time, it is also required to have excellent quietness.
Conventionally, synthetic hydrocarbon oil has been used as a grease for bearings, providing excellent lubricity in a wide temperature range from low temperature to high temperature, suppressing the occurrence of abnormal noise in the bearing, and excellent in high temperature durability for a long time. A base oil composed of an ester oil is blended with a urea-based thickener (Patent Document 1). In addition, it is used in bearings for automobile pulleys and is added to a base oil with a predetermined viscosity consisting of synthetic hydrocarbons and ester oils as a grease that suppresses brittle peeling of bearing surfaces and ball surfaces and abnormal noise during cold. The thing which mix | blended the alicyclic diurea compound as a thickener is known (patent document 2). Further, as a grease having a long seizure life under high-temperature and high-speed rotation conditions, a grease containing an ester oil in a base oil and 3 to 30% by weight of a predetermined diurea compound as a thickener is known (Patent Document 3).
As shown in Patent Documents 1 to 3, greases using a diurea compound as a thickener are known as greases excellent in high temperature durability. The diurea compound used in each of these patent documents is obtained by reacting diphenylmethane diisocyanate with a monoamine.

  However, even if it is a lubricating composition using a base oil containing an ester oil or a synthetic hydrocarbon oil as a base oil and a diurea compound as a thickener, as shown in each of the above patent documents, When encapsulated in bearings used in recent home appliances and industrial equipment, there is a problem that performance such as high temperature and high speed durability required for these bearings in recent years cannot always be satisfied.

  For example, along with the recent high performance and high output of automobiles, electrical accessory parts are becoming smaller, lighter, more functional and faster, and the usage environment of bearings tends to become higher. As grease for electrical accessory bearings, urea grease using the above-mentioned diurea compound is often used. However, in high temperature applications exceeding 180 ° C., heat resistance is insufficient and it is difficult to use. For this reason, fluorine grease using a fluorine compound as a base oil or thickener may be used. However, as compared with urea grease, fluorine grease is expensive in each stage, so that there is a problem that it cannot be used industrially for general purposes.

As a lubricating grease for high temperature and high load, there is known a lubricating grease in which two cyclic imide bonds are essential in one molecule, and a compound having two urea bonds, urethane bonds, or amide bonds is used as a thickener. (Patent Document 4).
However, the compound containing an imide bond requires not only an imide bond alone but also a combination with other urea bonds, urethane bonds, or amide bonds. A urea bond, a urethane bond, or an amide bond is inferior in heat resistance to an imide bond as seen in a comparison between a polyimide resin and a polyurethane resin or a polyamide resin. Therefore, even the thickener described in Patent Document 4 has a problem that it cannot satisfy the performance such as high temperature and high speed durability in recent years.

  As a grease using an imide compound as a thickener, a grease using a thickener having a specific imide structure in an ester base oil is known (Patent Document 5). However, there is a need for greases that are superior in high temperature and high speed durability than these greases.

Japanese Patent Laid-Open No. 9-208982 Japanese Patent No. 11-270566 JP 2001-107073 A JP 54-114506 A JP2011-168699A

  The present invention has been made in order to cope with such problems. A thickener capable of producing a grease excellent in high-temperature and high-speed durability, a method for producing the same, a grease using the thickener, and the grease The purpose is to provide a sealed grease bearing.

  The thickener of the present invention comprises an aromatic diimide compound obtained by reacting both in ester oil at a blending ratio of 2 mol of aromatic acid monoanhydride and 1 mol of aromatic diisocyanate. This aromatic diimide compound is characterized in that a differential curve of a thermogravimetric curve measured at a predetermined temperature increase rate in an inert atmosphere is represented by one peak. Here, the differential curve of the thermogravimetric curve refers to a graph of the first derivative obtained by differentiating a function representing the thermogravimetric curve. That is, if the graph of the function y = f (x) is a thermogravimetric curve, the differential curve is a graph of the function y = f ′ (x).

The method for producing a thickener according to the present invention is a first reaction step in which two moles of aromatic acid monoanhydride and 1 mole of aromatic diisocyanate are mixed, and both are reacted in ester oil at a temperature of 150 ° C. or lower. And after the first reaction step, in the ester oil, under the condition that the differential curve of the thermogravimetric curve obtained by measuring the reaction product in an inert atmosphere at a predetermined rate of temperature rise is represented by one peak. It has the 2nd reaction process made to react by.
In particular, the second reaction step is characterized by reacting at a temperature of 180 ° C. or higher.
In addition, the first and second reaction steps are performed by adding an anionic surfactant. Furthermore, the reaction is carried out in the presence of a tertiary amine catalyst.

The grease of the present invention comprises a thickener in the base oil, and this thickener is the thickener of the present invention.
The grease-enclosed bearing of the present invention is a grease-enclosed bearing in which the grease of the present invention is encapsulated.

The grease of the present invention uses a thickener obtained by reacting 2 moles of aromatic acid monoanhydride and 1 mole of aromatic diisocyanate in ester oil under predetermined conditions. High temperature and high speed durability can be improved. In particular, compared with the case where a conventional diurea compound is used as a thickener, the high-temperature and high-speed durability can be improved.
The grease-enclosed rolling bearing of the present invention is excellent in high-temperature and high-speed durability because the grease is encapsulated. For this reason, in recent years, it can be suitably used as a rolling bearing for home appliances and motors of industrial equipment used under high temperature and high speed rotation conditions.

It is an infrared spectrum figure which shows the production | generation process of an aromatic diimide compound. It is a thermogravimetric curve of aromatic diimide compound powder. It is sectional drawing of a deep groove ball bearing. It is a thermogravimetric curve of the powder obtained by the Example and the comparative example. 2 is a H-NMR chart of the powder obtained in Example 1. FIG.

  2 mol of aromatic acid monoanhydride and 1 mol of aromatic diisocyanate were reacted in ester oil to obtain an aromatic diimide compound. A study was carried out to further improve the high-temperature and high-speed durability of a bearing encapsulating grease using this aromatic diimide compound as a thickener. When the thermogravimetric curve of the aromatic diimide compound obtained by reacting in ester oil was measured, it was found that thermal decomposition occurred in two stages. When the reaction conditions were examined and an aromatic diimide compound in which thermal decomposition occurred in one stage, further improvement in the high-temperature and high-speed durability was observed. The present invention is based on such knowledge.

Examples of the aromatic acid monoanhydride that can be used in the present invention include dicarboxylic acid monoanhydrides in which two adjacent carbon atoms in the aromatic ring form an imide ring. A carboxyl group is bonded to each of two adjacent carbon atoms, and an acid monoanhydride group obtained by dehydration of these dicarboxys reacts with one isocyanate group of diisocyanates to form an imide ring.
Examples of the aromatic acid monoanhydride include phthalic anhydride and naphthalenedicarboxylic anhydride. Of these, phthalic anhydride is preferred.

  As the aromatic diisocyanate, any compound in which an isocyanate group is directly bonded to an aromatic ring can be used. For example, aromatic monocyclic diisocyanates such as phenylene diisocyanate, methylphenylene diisocyanate, dimethylphenylene diisocyanate, ethylphenylene diisocyanate, biphenyl diisocyanate, dimethylbiphenyl diisocyanate, diphenylmethane diisocyanate, diphenylethane diisocyanate, diphenylpropane diisocyanate, diphenylbutane diisocyanate, diphenyl ether diisocyanate, Aromatic bicyclic diisocyanates such as diphenylsulfone diisocyanate can be mentioned. These aromatic diamines may be substituted. Of these, diphenylmethane diisocyanate is preferred because of its industrial availability.

  Examples of the ester oil as a solvent for reacting an aromatic acid monoanhydride and an aromatic diisocyanate include aromatic ester oils and polyol ester oils. These aromatic ester oils and polyol ester oils serve as base oils for grease. As the base oil of the grease, it is particularly preferable to use a polyol ester oil because it is excellent in high-temperature and high-speed durability.

  The aromatic ester oil is preferably a compound obtained by reacting an aromatic polybasic acid or a derivative thereof with a higher alcohol. Aromatic polybasic acids include aromatic tricarboxylic acids such as trimellitic acid, biphenyltricarboxylic acid and naphthalenetricarboxylic acid, aromatic tetracarboxylic acids such as pyromellitic acid, biphenyltetracarboxylic acid, benzophenonetetracarboxylic acid and naphthalenetetracarboxylic acid. Derivatives such as acids or acid anhydrides thereof may be mentioned. As the higher alcohol, aliphatic monohydric alcohols having 4 or more carbon atoms such as octyl alcohol and decyl alcohol are preferable. Examples of the aromatic ester oil include trioctyl trimellitate, tridecyl trimellitate, tetraoctyl pyromellitate and the like.

The polyol ester oil is preferably a compound having a plurality of ester groups in a molecule obtained by a reaction between a polyol and a monobasic acid. The monobasic acid to be reacted with the polyol may be used alone or as a mixture. In the case of an oligoester, a dibasic acid may be used.
Examples of the polyol include trimethylolpropane, pentaerythritol, dipentaerythritol, neopentyl glycol, 2-methyl-2-propyl-1,3-propanediol, and the like. Examples of the monobasic acid include monovalent fatty acids having 4 to 18 carbon atoms. For example, valeric acid, caproic acid, caprylic acid, enanthic acid, pelargonic acid, capric acid, undecanoic acid, lauric acid, myristic acid, palmitic acid, tallow acid, stearic acid, caproleic acid, undecylenic acid, lindelic acid, tuzuic acid , Fizetheric acid, myristoleic acid, palmitoleic acid, petrothelic acid, oleic acid, elaidic acid, asclepic acid, vaccenic acid, sorbic acid, linoleic acid, linolenic acid, sabinic acid, ricinoleic acid and the like.

A method for producing the thickener of the present invention will be described.
An aromatic diimide compound can be produced by dissolving an aromatic acid monoanhydride and an aromatic diisocyanate in an ester base oil and reacting them.
Since the mixing ratio of the aromatic acid monoanhydride and the aromatic diisocyanate does not leave a reactive free radical, the isocyanate group of the aromatic diisocyanate and the carboxylic anhydride group of the aromatic acid monoanhydride are approximately equivalent. That is, it mix | blends in the ratio of 2 mol of aromatic acid monoanhydrides, and 1 mol of aromatic diisocyanates.

  In the above reaction, a reaction catalyst is preferably used, and a tertiary amine catalyst is preferable as the catalyst. Examples of the tertiary amine catalyst include triethylenediamine and tetraethylenediamine. As a compounding quantity of a catalyst, it is preferable that it is 0.3-1.0 mol per mol of aromatic diisocyanate.

  In the above reaction, it is preferable to add a surfactant. As the surfactant, a special polycarboxylic acid type polymer surfactant is preferable. As a commercial item of special polycarboxylic acid type high molecular surfactant, Kao Corporation make, brand name Poise 520, Poise 532A, homogenol L18, homogenol L1820, etc. are mentioned, for example. As a compounding quantity of surfactant, it is preferable that it is 1-10 mass parts per 100 mass parts of the whole compounding quantity except surfactant.

The reaction temperature in ester oil is set to 150 ° C. or lower, preferably 90 to 150 ° C., and the first reaction step is performed. In this step, the production of the aromatic diimide compound is started by the decarboxylation reaction between the aromatic acid monoanhydride and the aromatic diisocyanate.
FIG. 1 is an infrared spectrum diagram showing a production process of an aromatic diimide compound. FIG. 1A shows FT-IR after reacting at 150 ° C. for 10 hours, and FIG. 1B shows FT-IR after further reacting at 180 ° C. for 3 hours.
As shown in FIG. 1 (a), together with the peak due to the ester oil in the vicinity of 3000 cm ^-1 and around 1,000 to ^-1, characteristic peaks based on imide ring to 1780 cm ^-1 were observed.
As shown in FIG.1 (b), after making it react at 150 degreeC for 10 hours, and also making it react at 180 degreeC for 3 hours, the peak of 1780 cm < ^-1 > became clearer.

A non-solvent such as benzine or acetone was added to the reaction product reacted at 150 ° C. for 10 hours to precipitate and dry the aromatic diimide compound to obtain an aromatic diimide compound powder.
FIG. 2 is a thermogravimetric curve of the aromatic diimide compound powder obtained in the first and second reaction steps. The thermogravimetric curve was obtained by filling a sample in an aluminum pan with a thermogravimetric measuring device, raising the temperature from room temperature to 500 ° C. under a nitrogen atmosphere and a heating rate of 5 ° C./min, and measuring the weight loss at that time. In FIG. 2, a is a thermogravimetric curve after the first reaction step, b is a thermogravimetric curve after the second reaction step, a ′ is a differential curve of a, and b ′ is a differential curve of b. As shown in FIG. 2, two peaks a′1 and a′2 are clearly observed in the differential curve a ′, and the weight loss is about 15% starting from about 150 ° C. corresponding to the peak a′1. It was found that the main weight decrease gradually started from around 250 ° C. corresponding to the peak a′2 and thermal decomposition occurred in two stages.
On the other hand, the differential curve b ′ of the thermogravimetric curve b after the second reaction step has a single peak b′1, and it was found that one thermal decomposition occurred from around 300 ° C.

The present invention has a second reaction step in which the reaction product of the first step is reacted in ester oil in order to prevent thermal decomposition from being performed in two steps. By passing through the second reaction step, the thermal decomposition curve of the reaction product becomes a one-stage curve, and the differential curve can also be represented by one peak.
The reaction condition in the second reaction step may be a temperature exceeding 150 ° C., but the reaction is preferably performed at a temperature of 180 ° C. or higher in consideration of the reaction time. More preferably, it is 180 to 200 ° C. for 1 to 3 hours.
By passing through the second reaction step, as shown in FIG. 2, the thermal decomposition curve of the reaction product becomes a one-step curve b, and its differential curve b ′ also becomes one peak.

The grease of the present invention can be used as a grease having the ester oil as a base oil and the aromatic diimide compound as a thickener. For example, the reaction product that has undergone the second reaction step can be used as grease.
The blending ratio of the aromatic diimide compound as a thickener with respect to the base oil of the grease is preferably 10 to 60% by mass with respect to the entire grease. If it is less than 10% by mass, the grease is softened and easily leaks, making it difficult to enclose it in the bearing. On the other hand, if it exceeds 60% by mass, it hardens and becomes impractical as a grease for enclosing a bearing.

  The grease of the present invention can contain an amine-based or phenol-based antioxidant as necessary. Such antioxidants include alkylated diphenylamines such as p, p'-dioctyldiphenylamine, N, N'-diisopropyl-p-phenylenediamine, N, N'-di-sec-butyl-p-phenylenediamine, Phenyl-1-naphthylamine, phenyl-2-naphthylamine, diphenyl-p-phenylenediamine, dipyridylamine, oleylamidoamine, phenothiazine, N-methylphenothiazine, N-ethylphenothiazine, 3,7-dioctylphenothiazine, zinc alkyldithiophosphate, Examples include dilauryl thiodipropionate, distearyl thiodipropionate, dimyristyl thiodipropionate, and ditridecyl thiodipropionate. Moreover, sodium sebacate can be mix | blended as an antioxidant.

  The grease of the present invention can contain other known additives as necessary in order to enhance its excellent performance. As this additive, for example, extreme pressure agents such as chlorine, sulfur, phosphorus compounds, organic molybdenum, rust inhibitors such as petroleum sulfonate, dinonylnaphthalene sulfonate, sorbitan ester, metal deactivators such as benzotriazole, Examples thereof include viscosity index improvers such as polymethacrylate, polyisobutylene, and polystyrene, and these can be added alone or in combination of two or more.

  An example of the grease-filled bearing of the present invention is shown in FIG. FIG. 3 is a sectional view of a deep groove ball bearing which is a rolling bearing. In the grease-filled bearing 1, an inner ring 2 having an inner ring rolling surface 2a on the outer peripheral surface and an outer ring 3 having an outer ring rolling surface 3a on the inner peripheral surface are arranged concentrically, and the inner ring rolling surface 2a and the outer ring rolling surface 3a are arranged. A plurality of rolling elements 4 are arranged between the two. A seal member 6 is fixed to the cage 5 and the outer ring 3 that hold the plurality of rolling elements 4, and the grease 7 of the present invention is sealed at least around the rolling elements 4.

Example 1
As the ester oil, HATCO's product name Hatkor H3855 (148 mm ² / s (40 ° C.)) was used. 62 g of this ester oil was charged with 20.6 g (0.14 mol) of phthalic anhydride, 17.4 g (0.07 mol) of diphenylmethane diisocyanate (represented as MDI in Table 1), and 5 g of triethylenediamine as a reaction catalyst. The reaction was carried out at 150 ° C. for 10 hours. Thereafter, the temperature was maintained at 180 ° C. and left for 3 hours. The produced base grease was passed through a roll mill to obtain a semi-solid grease. The unit of grease composition in Table 1 is “g”. The reaction product was allowed to stand at 180 ° C. for 3 hours, and a part of the reaction product was collected and charged into a large amount of benzine to obtain a pale yellow powder. The thermogravimetric curve of this powder was measured under the conditions shown in FIG. The results are shown in FIG.

When the molecular weight of the light yellow powder was measured by the direct MS method (D-MS), the molecular weight was 458.12. When elemental analysis was performed, it was 75.4% by mass of carbon, 6.1% by mass of nitrogen, and 4.2% by mass of hydrogen. Furthermore, H-NMR was measured. The result of H-NMR is shown in FIG.
These results indicate that the light yellow powder is an aromatic diimide compound having the following chemical structure.

  Table 1 shows the measurement results of the penetration of the grease obtained in Example 1. Furthermore, the following high-temperature high-speed durability test was conducted, and these results are also shown in Table 1.

<High temperature high speed durability test>
A rolling bearing (bearing dimensions: inner diameter 20 mm, outer diameter 47 mm, width 14 mm) is filled with 1.8 g of the grease obtained in Example 1, the outer diameter of the bearing outer ring is 200 ° C., the radial load is 67 N, and the axial load is It was rotated at a rotational speed of 10,000 rpm under 67N, and the time (time (h)) required until seizure was measured according to ASTM D3336.

Example 2 and Example 3
Base oil, thickener, etc. were blended in the proportions shown in Table 1, reacted at 150 ° C. for 10 hours, then left at 180 ° C. for 2 hours (Example 2) and 1 hour (Example 3). A semi-solid grease was obtained in the same manner as in Example 1. A thermogravimetric curve measured under the same conditions as in Example 1 is shown in FIG. In addition, Table 1 shows the mixing penetration and the high-temperature high-speed durability test measured under the same conditions as in Example 1.

Example 4
A semisolid grease was obtained in the same manner as in Example 1 except that triethylenediamine was not added as a reaction catalyst. Table 1 shows the penetration and high temperature high speed durability tests measured under the same conditions as in Example 1.

Example 5
A base oil, a thickener and the like are blended in the proportions shown in Table 1, and as an anionic surfactant, a semisolid state is obtained in the same manner as in Example 4 except that 5 g of Kao's trade name Homogenol L1820 is blended. A grease was obtained. Table 1 shows the penetration and high temperature high speed durability tests measured under the same conditions as in Example 1.

Comparative Example 1
Base oil, thickener and the like were blended in the proportions shown in Table 1, and reacted at 150 ° C. for 10 hours. The produced base grease was passed through a roll mill to obtain a semi-solid grease. In addition, after reacting at 150 ° C. for 10 hours, a part of the reaction product was collected and put into a large amount of benzine to obtain a pale yellow powder. The thermogravimetric curve of this powder was measured under the conditions described above. The results are shown in FIG.

Comparative Example 2 and Comparative Example 3
Base oil, thickener and the like were blended in the proportions shown in Table 1, and reacted at 150 ° C. for 10 hours. The produced base grease was passed through a roll mill to obtain a semi-solid grease. The nonionic surfactant used in Comparative Example 3 is trade name Emulgen 104P manufactured by Kao Corporation. Table 1 shows the penetration and high temperature high speed durability tests measured under the same conditions as in Example 1.

Comparative Example 4
Greases were prepared using the base oil and thickener raw materials at the blending ratios shown in Table 1. MDI was heated and dissolved in half of the base oil, and p-toluidine was heated and dissolved in half of the base oil. The compounding amount of p-toluidine is twice the amount of MDI in molar ratio. The produced base grease was passed through a roll mill to obtain a semi-solid grease. Table 1 shows the penetration and high temperature high speed durability tests measured under the same conditions as in Example 1.

  As shown in Table 1, each of the examples using an aromatic diimide compound obtained by reacting at 150 ° C. for 10 hours and further at 180 ° C. as a thickener, It can be seen that the high temperature and high speed durability is superior to each comparative example using a diurea compound as a thickener. In addition, Example 3 had the same high-temperature and high-speed durability as Comparative Example 2, but was superior to Comparative Example 2 in that the thickener in use was less thermally decomposed and oil separation was difficult at the initial stage of operation. It was.

  Since the grease of the present invention uses an aromatic diimide compound as a thickener, it is excellent in high temperature and high speed durability. For this reason, in recent years, it can be suitably used as a rolling bearing for home appliances and motors of industrial equipment used under high temperature and high speed rotation conditions.

1 Grease filled bearing 2 Inner ring 3 Outer ring 4 Rolling element 5 Cage 6 Seal member 7 Grease

Claims (7)

A compound comprising an aromatic diimide compound obtained by reacting the aromatic acid monoanhydride and the aromatic diisocyanate in an ester oil at a blending ratio of 2 mol of aromatic acid monoanhydride and 1 mol of aromatic diisocyanate. An agent,
The aromatic diimide compound is a thickener characterized in that a differential curve of a thermogravimetric curve measured at a predetermined heating rate in an inert atmosphere is represented by one peak. A method for producing a thickener according to claim 1,
A first reaction step in which the aromatic acid monoanhydride and the aromatic diisocyanate are reacted in ester oil at a temperature of 150 ° C. or less at a mixing ratio of 2 mol of aromatic acid monoanhydride and 1 mol of aromatic diisocyanate. When,
After the first reaction step, the reaction product is reacted in the ester oil under the condition that the differential curve of the thermogravimetric curve measured at a predetermined rate of temperature increase in an inert atmosphere is represented by one peak. A method for producing a thickener, comprising a second reaction step.   The method for producing a thickener according to claim 2, wherein the second reaction step is performed at a temperature of 180 ° C or higher.   The method for producing a thickener according to claim 2 or 3, wherein the first and second reaction steps are carried out by adding an anionic surfactant.   5. The method for producing a thickener according to claim 2, wherein the first and second reaction steps are carried out in the presence of a tertiary amine catalyst. A grease comprising a thickener in a base oil,
The grease according to claim 1, wherein the thickener is the thickener according to claim 1.   A grease-enclosed bearing in which grease is encapsulated, wherein the grease is the grease according to claim 6.