JP6612031B2 - Grease manufacturing method - Google Patents

Description

  The present invention relates to a method for producing grease.

Grease, especially diurea-based grease, contains a solid fine substance generally called “dama”. The lumps include those that are thought to be derived from the reaction product of isocyanate and amine, and impurities that are mixed in during the manufacturing process and storage. Also in this specification, the term “dama” includes both those derived from the reactants and impurities.
In a general method for producing urea grease, an isocyanate is mixed with a base oil and heated to about 60 ° C., and a solution of about 60 ° C. mixed with an amine is added to the base oil and stirred for a while. After being heated to room temperature, it is allowed to cool to room temperature. However, such a method requires time for manufacturing and easily generates lumps. In addition, it is known that large lumps deteriorate the acoustic characteristics when grease is applied to sliding devices such as bearings. Furthermore, since the non-uniform structure consisting of large lumps contributes little to the original performance of the grease, the efficiency as a thickener is reduced. In other words, many thickeners are required to achieve a certain hardness.

  In view of this, there has been proposed a grease manufacturing method that suppresses generation of large lumps and improves acoustic characteristics (see Patent Documents 1 and 2). The production method of Patent Document 1 is a method in which an amine solution (isocyanate solution) is made into droplets having a diameter of 300 μm or less with a spray nozzle and charged into the isocyanate solution (amine solution), and a method in which both solutions are sprayed and reacted. By this manufacturing method, the particle size of the lumps made of a thickener (urea compound) is controlled to be less than 100 μm (about several tens of μm). The manufacturing method of Patent Document 2 is a method in which an amine solution and an isocyanate solution are pressurized to a predetermined pressure using a pressurizing apparatus, and both solutions are collided and reacted. With this manufacturing method, the size of the dama is controlled to about several hundreds to several tens of μm. A method for controlling the particle size during the production of grease by high-pressure jet mixing has also been proposed (see Patent Document 3).

JP 2000-248290 A Japanese Patent Laid-Open No. 3-190996 JP 2014-208551 A

  However, in the production methods described in Patent Documents 1 and 2, environmental pollution and phytotoxicity due to scattering of amines and isocyanates are a concern, and the fineness of lumps is not always sufficient. Therefore, when the obtained grease is applied to a sliding device such as a bearing, a great improvement in acoustic characteristics cannot be expected. In addition, the manufacturing method described in Patent Document 3 has a problem in the design of equipment to withstand high pressure, and the obtained grease cannot be expected to greatly improve acoustic characteristics.

  The present invention provides a method for producing grease that is very excellent in acoustic characteristics.

That is, the grease production method of the present invention is 10 ² s ^{−1 with respect} to at least one of the base oil 1 containing the thickener precursor 1 and the base oil 2 containing the thickener precursor 2. The above-mentioned minimum shear rate is given, the base oil 1 and the base oil 2 are mixed while maintaining the minimum shear rate to form a mixture, and a thickener is formed in the mixture. To do.
In the present invention, in one reaction vessel, the base oil 1 containing the thickener precursor 1 is given a minimum shear rate of 10 ² s ⁻¹ or more, and the base oil containing the thickener precursor 2. 2 is given a minimum shear rate of 10 ² s ⁻¹ or more, and the base oil 1 and the base oil 2 are mixed while maintaining the minimum shear rate to obtain a mixed solution. It is preferable to form a thickener.
In the present invention, the base oil 1 containing the thickener precursor 1 is given a minimum shear rate of 10 ² s ⁻¹ or more, and the thickener precursor 2 is maintained while maintaining the minimum shear rate. It is preferable to add the base oil 2 containing the base oil 1 to form a mixture and form a thickener in the mixture.

  According to the production method of the present invention, it is possible to provide a grease having excellent acoustic characteristics.

In embodiment of this invention, the schematic sectional drawing which shows an example of the manufacturing method (manufacturing apparatus) of urea grease. The figure which shows both the outline of a side and the outline of an upper surface about the manufacturing apparatus of FIG. In other embodiment of this invention, the figure which shows both the outline of the side in the manufacturing apparatus of urea grease, and the outline of the upper surface. Schematic which shows the manufacturing method of the conventional urea grease.

  The inventors have found that when an isocyanate solution and an amine solution are mixed, generation of urea molecules and formation of a bundle (fiber structure) occur in a very short time. And in the conventional manufacturing method, since the shear rate at the time of mixing was low and nonuniform, it was estimated that nonuniform structures, such as a thick bundle and a big dama, were formed. The present inventor pays attention to this point, puts either one of the isocyanate solution or the amine solution under high-speed shearing, then mixes the other solution, while maintaining a high shear rate with respect to the mixed solution uniformly. It has been found that the use of grease makes it possible to reduce lumps as compared with a normal manufacturing method. It was also found that the grease obtained by this method is very excellent in acoustic characteristics (for example, BeQuiet method). The present invention has been completed based on these findings.

Hereinafter, an embodiment of the present invention will be described.
In a grease manufacturing method (hereinafter also referred to as “the present manufacturing method”) according to an embodiment of the present invention, a base oil 1 containing a thickener precursor 1 and a base oil containing a thickener precursor 2 are used. The minimum shear rate of 10 ² s ⁻¹ or more is given to at least one of 2 and the base oil 1 and the base oil 2 are mixed while maintaining the minimum shear rate to obtain a mixed solution, A thickener is formed in the mixture.
Further, in this embodiment, the minimum shear rate of 10 ² s ⁻¹ or more is given to the base oil 1 containing the thickener precursor 1 in one reaction vessel, and the thickener precursor 2 is added. The base oil 2 containing a minimum shear rate of 10 ² s ⁻¹ or more is mixed, and the base oil 1 and the base oil 2 are mixed while maintaining the minimum shear rate to obtain a mixed solution. The thickener is preferably formed in the mixed solution. Alternatively, the base oil 1 containing the thickener precursor 1 is given a minimum shear rate of 10 ² s ⁻¹ or more, and the base oil containing the thickener precursor 2 is maintained while maintaining the minimum shear rate. It is also preferable that 2 is added to the base oil 1 to form a mixed solution, and a thickener is formed in the mixed solution.
In any of the above embodiments, the thickener precursor 1 and the thickener precursor 2 are reacted to increase while maintaining the high shear rate of the mixed liquid (mixed base oil) and suppressing the formation of lumps. It is characterized by the fact that it is a fungicide. Hereinafter, this production method will be described in detail.

[Raw material for grease production]
(Base oil)
The base oil 1 and the base oil 2 used in the production method are not particularly limited, and examples thereof include mineral base oils and synthetic base oils used for normal grease production. These can be used alone or as a mixture.
As the mineral oil base oil, those refined by appropriately combining vacuum distillation, solvent deburring, solvent extraction, hydrocracking, solvent dewaxing, sulfuric acid washing, clay refining, hydrogenation refining and the like can be used. Synthetic base oils include polyalphaolefin (PAO) base oils, other hydrocarbon base oils, ester base oils, alkyl diphenyl ether base oils, polyalkylene glycol base oils (PAG), and alkylbenzenes. Base oils and the like. 40 ° C. kinematic viscosity of the base oil 1 and base oil 2 is preferably 10 mm ² / s or more 600 mm ² / s or less, more preferably at most 20 mm ² / s or more 300 mm ² / s, 30 mm ² / More preferably, it is s or more and 100 mm ² / s or less.
In consideration of the compatibility of the base oil 1 and the base oil 2, it is preferable that they have similar polarities and similar viscosity characteristics. Therefore, the base oil 1 and the base oil 2 are most preferably the same base oil.

(Thickener)
In this manufacturing method, a thickener is formed from two types of thickener precursors. Although it does not specifically limit as such a thickener precursor, When a thickener is a urea, a monoamine and isocyanate (diisocyanate) are mentioned as a thickener precursor.
Examples of monoamines include aniline, p-toluidine, and naphthylamine for aromatic monoamines, and hexylamine, cyclohexylamine, octylamine, dodecylamine, hexadecylamine, and eicosylamine for aliphatic monoamines. .
The polyurea compound can be obtained, for example, by reacting diisocyanate with a monoamine or diamine. Examples of diisocyanate and monoamine include those used for the production of diurea compounds. Examples of diamines include ethylenediamine, propanediamine, butanediamine, hexanediamine, octanediamine, phenylenediamine, tolylenediamine, xylenediamine, and And diaminodiphenylmethane.
Examples of the isocyanate include diphenylmethane-4,4′-diisocyanate (MDI), tolylene diisocyanate, and naphthylene-1,5-diisocyanate. Each of the above-described amines may be used alone, or a plurality of amines may be mixed and used. In addition, each of the above-described isocyanates may be used alone, or a plurality of isocyanates may be mixed and used.
Diurea grease that does not easily generate large lumps is produced by introducing the isocyanate and monoamine in a molar ratio of 1: 2 into the reaction vessel (grease production equipment) in order and mixing and reacting them while applying high-speed shearing as described later. can do.

[Grease production method]
In this production method, a minimum shear rate of 10 ² s ⁻¹ or more is applied to at least one of the base oil 1 containing the thickener precursor 1 and the base oil 2 containing the thickener precursor 2. The base oil 1 and the base oil 2 are mixed while maintaining the minimum shear rate to form a mixture, and a thickener is formed in the mixture.
Further, in one reaction vessel, the base oil 1 containing the thickener precursor 1 is given a minimum shear rate of 10 ² s ⁻¹ or more, and the base oil 2 containing the thickener precursor 2 is given. A minimum shear rate of 10 ² s ⁻¹ or more is given, and the base oil 1 and the base oil 2 are mixed while maintaining the minimum shear rate to obtain a mixture, and the mixture is increased in the mixture. An agent may be formed. Or after giving the minimum shear rate of 10 ² s ⁻¹ or more to the base oil 1 containing the thickener precursor 1, the base oil 2 containing the thickener precursor 2 is applied to the base oil 1. Further, mixing may be performed while maintaining the above minimum shear rate. Then, the base oil 1 and the base oil 2 are reacted while being mixed and dispersed to form a thickener, and grease is formed.
That is, in any of the above cases, it is extremely important to mix in a state where the minimum shear rate of at least one of the base oil 1 or the base oil 2 is maintained at 10 ² s ⁻¹ or more. As described above, the base oil 1 and the base oil 2 are mixed under a predetermined high-speed shear, thereby suppressing generation and coarsening of lumps.

Moreover, although the above-mentioned minimum shear rate is 10 ² s ⁻¹ or more, it is preferably 10 ³ s ⁻¹ or more, more preferably 10 ⁴ s ⁻¹ or more. A higher minimum shear rate improves the dispersion state of thickener precursors 1 and 2 and the resulting thickener, resulting in a more uniform grease structure. That is, the bundle of thickener molecules does not become thick and the lumps do not become large.
However, from the viewpoint of safety of the apparatus, heat generation due to shearing and the like and removal of the heat, the above-mentioned minimum shear rate is preferably 10 ⁷ s ⁻¹ or less.
Such a high shear rate can be imparted, for example, by introducing a mixed solution into a reaction vessel that generates shear by relative motion between opposing wall surfaces. In addition, the minimum shear rate is synonymous with the minimum shear rate mentioned later, and means the lower limit of the shear rate in the site | part which provides shear to a liquid mixture in a reaction container.

In this production method, the time for maintaining the shear rate of the mixed liquid at 10 ² s ⁻¹ or higher (high shearing portion residence time) is preferably 0.002 seconds or longer, and 0.02 seconds or longer and 100 seconds or shorter. More preferably, it is 0.2 seconds or more and 10 seconds or less. When the high shearing portion residence time is 0.002 seconds or more, the thickener is more excellently dispersed. Further, when the high shearing portion residence time is 100 seconds or less, the apparatus can be easily miniaturized with respect to the amount of grease to be manufactured.
The high shear portion residence time (s) can be defined as follows.
High shear part residence time (s) = High shear part volume (mL) / {Flow rate of base oil 1 (mL / s) + Flow rate of base oil 2 (mL / s)}

An example of a grease manufacturing apparatus (reaction vessel) capable of generating a high shear rate is a manufacturing apparatus having a structure as shown in FIG. FIG. 2 shows both the outline of the side and the outline of the upper surface of the manufacturing apparatus of FIG.
The manufacturing apparatus of FIG. 1 has a structure in which the base oil 2 is mixed after maintaining the base oil 1 at a predetermined minimum shear rate, and high-speed shearing can be imparted to and maintained in the mixed solution. High-speed shearing is imparted to the mixed solution by a gap (gap a, b) between the high-speed rotating part and the inner wall of the reaction vessel. The high-speed rotating part may have a constant diameter in the direction of the rotation axis (a = b) or a structure with a different gap. Such a gap is adjusted by changing the diameter of the high-speed rotating part in the direction of the rotation axis, or by making the high-speed rotating part a truncated cone and moving the high-speed rotating part up and down with respect to the inner wall of the reaction vessel provided with a taper. May be.
Furthermore, you may give extrusion capability by making the part with a large gap into the screw or spiral shape which inclined continuously.

  FIG. 3 shows a reaction vessel (grease production apparatus) having a different mode from that in FIG. 1, but the portions (c, d) having different gaps are arranged in the rotation direction. In the case of this manufacturing apparatus, it is possible to provide an extrusion ability like a screw by inclining a portion having a large gap with respect to the rotation axis. Also in this reaction container of FIG. 3, the introduction positions of the base oil 1 and the base oil 2 are arbitrary as long as the above-described minimum shear rate can be imparted to the base oil 1 and the mixed liquid.

In the above reaction vessel, the ratio (Max / Min) between the maximum shear rate (Max) and the minimum shear rate (Min) in the shear applied to the mixed solution is preferably 50 or less, and more preferably 30 or less. More preferably, it is 10 or less. Since the shear rate with respect to the mixed liquid is as uniform as possible, the grease is not coarsened and a uniform grease structure is obtained.
Here, the maximum shear rate (Max) is the highest shear rate applied to the mixed solution at the shear portion, and the minimum shear rate (Min) is applied to the mixed solution at the shear portion. The lowest shear rate is defined as follows when the reaction vessel shown in FIG. 1 is taken as an example.
Max = (Linear velocity of the surface of the high-speed rotating part in the portion where the gap between the surface of the high-speed rotating part and the inner wall surface of the container is minimized / the gap)
Min = (Linear velocity of the surface of the high-speed rotating part at the portion where the gap between the surface of the high-speed rotating part and the inner wall surface of the container is maximized / the gap)
In FIG. 1, the gap in the Max calculation is a, and the gap in the Min calculation is b.
As described above, since Max / Min is preferably smaller, a = b ideally. That is, in the case of the reaction container of the type shown in FIG. 1, the high-speed rotating part is most preferably a cylindrical shape having a uniform diameter in the vertical direction.

  This production method can be applied to all grease production methods including a step of mixing a solution comprising the base oil 1 and the thickener precursor 1 and a solution comprising the base oil 2 and the thickener precursor 2. The temperature conditions for producing the thickener vary depending on the precursor used, but when producing urea as the thickener, it is preferably about 50 ° C. or higher and 200 ° C. or lower. When this temperature is 50 ° C. or higher, isocyanate is easily dissolved in the base oil, and when it is 200 ° C. or lower, deterioration of the base oil can be sufficiently suppressed. The temperature of the base oil and amine solution before introduction of the reaction vessel is preferably about 50 ° C. or more and 100 ° C. or less.

[Post-process in grease manufacturing method]
In this production method, the grease obtained by the production method described above may be further kneaded. For this kneading, a roll mill generally used in grease production can be used. The above grease may be passed through a roll mill two or more times.
Moreover, in this manufacturing method, it is preferable to heat the grease obtained by the manufacturing method described above for controlling the consistency. The heating temperature is preferably 80 ° C. or higher and 200 ° C. or lower, more preferably 100 ° C. or higher and 180 ° C. or lower, and further preferably 130 ° C. or higher and 170 ° C. or lower. Furthermore, in order to heat uniformly, you may knead | mix and stir. Note that a heating furnace or the like may be used for heating.

  The grease obtained by this production method is very excellent in acoustic characteristics. For example, when tested using a Bequiet grease noise tester manufactured by the Swedish SKF group, a GN class of 4 can be obtained.

〔Additive〕
Various additives can be further blended in the grease obtained by this production method. Such additives include antioxidants, extreme pressure agents, rust inhibitors and the like.
Examples of the antioxidant include amine-based antioxidants such as alkylated diphenylamine, phenyl-α-naphthylamine, and alkylated-α-naphthylamine, 2,6-di-t-butyl-4-methylphenol, and 4, And phenolic antioxidants such as 4-methylenebis (2,6-di-t-butylphenol). A preferable blending amount of these antioxidants is about 0.05% by mass or more and 2% by mass or less based on the total amount of grease.

  Extreme pressure agents include zinc dialkyldithiophosphates, molybdenum dialkyldithiophosphates, ashless dithiocarbamates, zinc dithiocarbamates, molybdenum dithiocarbamates, sulfur compounds (sulfurized oils, sulfurized olefins, polysulfides, sulfide mineral oils, thiophosphorus Acid, thioterpene, dialkylthiodipyropionate, etc.), phosphate ester, phosphite ester (tricresyl phosphate, triphenyl phosphite, etc.) and the like. A preferable blending amount of the extreme pressure agent is about 0.1% by mass or more and 5% by mass or less based on the total amount of grease.

Examples of rust preventives include benzotriazole, zinc stearate, succinic acid ester, succinic acid derivative, thiadiazole, benzotriazole, benzotriazole derivative, sodium nitrite, petroleum sulfonate, sorbitan monooleate, fatty acid soap, and amine compound. Can be mentioned. A preferable blending amount of the rust inhibitor is about 0.01% by mass or more and 10% by mass or less based on the total amount of grease.
The various additives as described above may be blended alone or in any combination of several kinds.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these descriptions. Specifically, urea grease was produced under various conditions shown below, and the acoustic characteristics of the obtained grease were evaluated.
[Example 1]
Grease was produced in the reaction vessel (high dispersion production apparatus) shown in FIG.
A base oil 1 (PAO: 40 ° C. kinematic viscosity 47 mm ² / s) containing 6.03% by mass of MDI (diphenylmethane-4,4′-diisocyanate) and heated to 70 ° C. was supplied into the reaction vessel at a flow rate of 5.0 mL / Base oil 2 containing 3.35% by mass of cyclohexylamine and 13.68% by mass of stearylamine while being continuously introduced at s, and heated to 70 ° C. (PAO: 40 ° C. kinematic viscosity 47 mm ² / s) Was continuously introduced at a flow rate of 2.9 mL / s into a high shear portion in the reaction vessel. Here, the maximum shear rate was 33,000 s ⁻¹ and the minimum shear rate was 6,600 s ⁻¹ . Moreover, the ratio (Max / Min) of the maximum shear rate (Max) and the minimum shear rate (Min) was 5, and the high shear portion residence time of the mixed solution was 0.25 seconds.
The grease discharged from the reaction vessel was placed in a vessel preheated to 90 ° C., heated to 160 ° C. over about 30 minutes, and then held at 160 ° C. for 1 hour. Thereafter, the mixture was allowed to cool while maintaining stirring. The amount of thickener in the manufactured grease was about 10% by mass. The obtained grease was stirred and defoamed with a planetary stirring deaerator (MAZERUSTAR model KK-V300SS-I, manufactured by Kurashiki Boseki Co., Ltd.), and then mixed with a blending consistency (JIS K 2220). While being measured, it was subjected to acoustic measurement by the BeQuiet method. The results are shown in Table 1.

[Example 2]
Grease was produced in the same reaction vessel as in Example 1.
Base oil 1 (PAO: 40 ° C. kinematic viscosity 47 mm ² / s) containing 7.70% by mass of MDI (diphenylmethane-4,4′-diisocyanate) and heated to 70 ° C. was supplied into the reaction vessel at a flow rate of 4.0 mL / Base oil 2 containing 2.42% by mass of cyclohexylamine and 9.89% by mass of stearylamine while being continuously introduced at s, and heated to 70 ° C. (PAO: 40 ° C. kinematic viscosity 47 mm ² / s) Was continuously introduced at a flow rate of 4.1 mL / s into a high shear portion in the reaction vessel. Here, the maximum shear rate was 11,000 s ⁻¹ and the minimum shear rate was 5,600 s ⁻¹ . Moreover, the ratio (Max / Min) of the maximum shear rate (Max) and the minimum shear rate (Min) was 2.0, and the high shear portion residence time of the mixed solution was 0.20 seconds.
The grease discharged from the reaction vessel was placed in a vessel preheated to 90 ° C., heated to 160 ° C. over about 30 minutes, and then held at 160 ° C. for 1 hour. Thereafter, the mixture was allowed to cool while maintaining stirring. The amount of thickener in the manufactured grease was about 10% by mass. The obtained grease was evaluated in the same manner as in Example 1, and the results are shown in Table 1.

[Comparative Example 1]
Grease was manufactured by the conventional method using the reaction container shown in FIG.
60 ° C. was hold base oil 1: to (PAO 40 ° C. kinematic viscosity 47mm ² / s, MDI 7.25 wt% content), 60 ° C. of the base oil 2 (PAO: 40 ° C. kinematic viscosity 47 mm ² / s, Cyclohexylamine 2.59 mass% and stearylamine 10.05 mass%) was added dropwise with stirring at 250 rpm. Here, the maximum shear rate was about 100 s ⁻¹ and the minimum shear rate was 1.23 s ⁻¹ . The ratio (Max / Min) between the maximum shear rate (Max) and the minimum shear rate (Min) was about 81.
After dripping the amine solution, the temperature was raised to 160 ° C. and maintained for 1 hour while continuing stirring. Thereafter, the mixture was allowed to cool with stirring. The amount of thickener in the manufactured grease was about 10% by mass. The obtained grease was evaluated in the same manner as in Example 1, and the results are shown in Table 1.

１）Ｃy：シクロヘキシルアミン、Ｃ18：ステアリルアミン

1) Cy: cyclohexylamine, C18: stearylamine

〔Evaluation results〕
From the results in Table 1, it can be seen that each of the urea greases of Examples 1 and 2 obtained by the manufacturing method of the present embodiment has a GN class of 4 by the BeQuiet method and is extremely excellent in acoustic characteristics.
On the other hand, the urea grease of Comparative Example 1 manufactured by the conventional method is inferior in acoustic characteristics by the BeQuiet method.

Claims (7)

Giving a minimum shear rate of 10 ² s ⁻¹ or more to at least one of the base oil 1 containing the thickener precursor 1 and the base oil 2 containing the thickener precursor 2;
The base oil 1 and the base oil 2 are mixed while maintaining the minimum shear rate to obtain a mixed solution,
Forming a thickener in the mixture ,
The time for maintaining the minimum shear rate of the mixed liquid comprising the base oil 1 and the base oil 2 at 10 ² s ⁻¹ or more is 0.002 seconds or more,
Method of manufacturing the grease. In the manufacturing method of the grease of Claim 1,
Giving a minimum shear rate of 10 ² s ⁻¹ or more to the base oil 1 containing the thickener precursor 1 in one reaction vessel;
Giving a minimum shear rate of 10 ² s ⁻¹ or more to the base oil 2 containing the thickener precursor 2,
The base oil 1 and the base oil 2 are mixed to maintain a minimum shear rate of each to form a mixed solution,
A thickening agent is formed in the mixed solution. In the manufacturing method of the grease of Claim 1 or 2 ,
The method for producing grease, wherein the minimum shear rate of the mixed solution is 10 ⁷ s ⁻¹ or less. In the manufacturing method of the grease of any one of Claim 1- Claim 3 ,
A grease manufacturing method, wherein a ratio (Max / Min) of a maximum shear rate (Max) and a minimum shear rate (Min) in a shear rate applied to the mixed solution is 50 or less. In the manufacturing method of the grease of any one of Claim 1- Claim 4 ,
The precursor 1 is a monoamine and the precursor 2 is a diisocyanate, or
The method for producing grease, wherein the precursor 1 is a diisocyanate and the precursor 2 is a monoamine. In the manufacturing method of the grease of any one of Claim 1- Claim 5 ,
A method for producing grease, wherein the mixed liquid is introduced into a container that generates shear by relative motion between opposing wall surfaces to obtain the minimum shear rate. The grease obtained by the grease production method according to any one of claims 1 to 6 , further heated to a temperature of 80 ° C or higher.

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