阅读说明：本技术 润滑油组合物的检查方法及润滑油组合物的制造方法 (Method for inspecting lubricating oil composition and method for producing lubricating oil composition ) 是由 门田隆二 高宇 栗谷真澄 近藤邦夫 于 2018-12-04 设计创作，主要内容包括：一种润滑油组合物的检查方法,是包含基油和富勒烯的润滑油组合物的检查方法,其中,测定上述润滑油组合物的拉膜长度和由动态光散射法得到的粒径分布中的最多径中的至少一者,筛选其测定值在设定的范围内的上述润滑油组合物。(A method for inspecting a lubricating oil composition containing a base oil and a fullerene, wherein at least one of the film length of the lubricating oil composition and the maximum diameter in the particle size distribution obtained by a dynamic light scattering method is measured, and the lubricating oil composition having a measured value within a predetermined range is screened.)

1. A method for inspecting a lubricating oil composition comprising a base oil and a fullerene,

at least one of the drawn film length and the particle size distribution obtained by the dynamic light scattering method of the lubricating oil composition is measured, and the lubricating oil composition whose measured value is within a predetermined range is screened.

2. The method for inspecting a lubricating oil composition according to claim 1, wherein said film-drawing length and said multipath are measured, and said lubricating oil composition having both of the measured values within a predetermined range is screened.

3. A method for producing a lubricating oil composition, comprising the steps of: a lubricating oil composition obtained by mixing a base oil and a fullerene is screened by the method for inspecting a lubricating oil composition according to claim 1 or 2.

Technical Field

The present invention relates to a method for inspecting a lubricating oil composition and a method for producing a lubricating oil composition.

The present application claims priority based on Japanese application No. 2017,234587, 12/6/2017, the contents of which are incorporated herein by reference.

Background

In recent years, with the increase in speed, efficiency, and energy saving, there has been a strong demand for improving the performance of lubricating oils used in automobiles, home appliances, industrial machines, and the like. In order to improve the properties of the lubricating oil composition so as to be suitable for the use thereof, various additives such as an antioxidant, an extreme pressure additive, an anti-rust additive, and a corrosion inhibitor are blended in the lubricating oil composition.

In response to these demands, an additive composition for engine lubricating oils is known in which fullerene as a nano carbon particle, an organic solvent, a viscosity index improver, a friction modifier, and a detergent dispersant are blended with a lubricating base oil such as mineral oil or ester oil in order to improve a plurality of performances such as low friction, increase in torque, and reduction in fuel consumption at the same time (for example, see patent document 1).

Furthermore, fullerene may be added to a lubricating oil composition used in a refrigerant compressor (see, for example, patent document 2).

In general, important characteristics of a lubricating oil composition include a friction coefficient, but measurement is laborious. Therefore, in the production process of the lubricating oil composition, the properties of the lubricating oil composition are specified by using, as indices, density, dynamic viscosity, viscosity index, pour point, total oxidation, and the like, which are easy to measure (for example, see non-patent document 1).

Disclosure of Invention

Problems to be solved by the invention

However, even when the lubricant oil composition containing fullerene described in non-patent document 1 and the like is subjected to product management using the above index, a product having stably reproduced lubricating properties such as a friction coefficient cannot be obtained. That is, even when the characteristics of the product are expressed as numerical values by the above-described index and the product falling within a certain range is regarded as acceptable, the lubrication characteristics may fluctuate beyond the allowable range.

Further, by measuring the lubricating properties of the products of the lubricating oil composition, it is possible to screen products having lubricating properties within an allowable range. However, in order to measure the lubricating properties of the lubricating oil composition, it is necessary to perform a friction test such as a ball-and-disk friction test for each product lot. In this case, the labor and time, and the cost of the test substrate and the like increase. Therefore, the friction test is not suitable for every manufacturing lot to be carried out.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a method for inspecting a lubricating oil composition and a method for producing a lubricating oil composition, which can stably reproduce friction characteristics even in the case of a lubricating oil composition containing fullerene by a relatively easy measurement method.

Means for solving the problems

[1] A method for inspecting a lubricating oil composition comprising a base oil and a fullerene,

at least one of the drawn film length and the particle size distribution obtained by the dynamic light scattering method of the lubricating oil composition is measured, and the lubricating oil composition whose measured value is within a predetermined range is screened.

[2] The method for inspecting a lubricating oil composition according to [1], wherein the film-drawing length and the maximum path are measured, and the lubricating oil composition having both the measured values within a predetermined range is screened.

[3] A method for producing a lubricating oil composition, comprising the steps of: a lubricating oil composition obtained by mixing a base oil and a fullerene is screened by the method for inspecting a lubricating oil composition according to [1] or [2 ].

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, it is possible to provide a method for inspecting a lubricating oil composition and a method for producing a lubricating oil composition, which can stably reproduce frictional characteristics even in the case of a lubricating oil composition containing fullerene by a relatively easy measurement method.

Drawings

FIG. 1 is a graph showing the relationship between the drawn film length and the friction coefficient of the lubricating oil composition in example 1.

FIG. 2 is a graph showing the relationship between the maximum diameter and the friction coefficient of the lubricating oil composition in example 2.

FIG. 3 is a graph showing the relationship between the dynamic viscosity and the friction coefficient of the lubricating oil composition in comparative example 1.

Detailed Description

Embodiments of the method for inspecting a lubricating oil composition and the method for producing a lubricating oil composition of the present invention will be described.

The present embodiment is specifically described to better understand the gist of the present invention. The present embodiment is not intended to limit the present invention unless otherwise specified.

[ method for inspecting lubricating oil composition ]

The method for inspecting a lubricating oil composition according to the present embodiment is a method for inspecting a lubricating oil composition containing a base oil and fullerene. The method for inspecting a lubricating oil composition according to the present embodiment is a method for measuring at least one of the drawn film length of a lubricating oil composition and the maximum diameter of the particle size distribution obtained by the dynamic light scattering method, and screening a lubricating oil composition whose measured value is within a predetermined range.

(lubricating oil composition)

The lubricating oil composition to be inspected by the method for inspecting a lubricating oil composition according to the present embodiment includes a base oil and fullerene.

(base oil)

The base oil included in the lubricating oil composition in the present embodiment is not particularly limited, and generally, mineral oil and synthetic oil widely used as the base oil of lubricating oil are suitably used.

Mineral oils used as lubricating oils are generally those in which carbon-carbon double bonds contained in the oil are saturated by hydrogenation and converted into saturated hydrocarbons. Examples of such mineral oils include paraffin-based oils and naphthene-based oils.

Specific examples of the synthetic oil include poly α -olefin, diester, polyalkylene glycol, poly α -olefin, polyalkyl vinyl ether, polybutene, isoparaffin, olefin copolymer, alkylbenzene, alkylnaphthalene, diisodecyl adipate, monoester, dibasic ester, tribasic ester, polyol ester (trimethylolpropane caprylate, trimethylolpropane pelargonate, pentaerythritol 2-ethylhexanoate, pentaerythritol pelargonate, etc.), dialkyl diphenyl ether, alkyl diphenyl sulfide, polyphenyl ether, silicone lubricant (dimethyl silicone, etc.), perfluoropolyether, etc.

Among these synthetic oils, poly α -olefin, diester, polyol ester, polyalkylene glycol, and polyalkylvinyl ether are more preferably used.

These mineral oils and synthetic oils may be used alone in 1 kind, or 2 or more kinds selected from them may be used in combination in an arbitrary ratio.

(Fullerene)

The structure and production method of the fullerene included in the lubricating oil composition of the present embodiment are not particularly limited, and various methods can be used. As the fullerene, for example, C which is relatively easily available₆₀、C₇Further higher fullerenes, or mixtures thereof. In fullerene, the fullerene is mainly used for the preparation of the fullereneC is preferred in view of high solubility in lubricating oil₆₀And C₇₀More preferably C, from the viewpoint of less coloring of the lubricating oil₆₀. When a mixture of 2 or more kinds of fullerenes is used as the fullerene, it preferably contains C₆₀50% by mass or more.

The fullerene may be chemically modified for the purpose of further improving the solubility in the base oil. Examples of the chemically modified fullerene include a methanofullerene (phenyl C61 methyl butyrate ([60] PCBM), diphenyl C62 methyl dibutyrate (═ Bis [60] PCBM), phenyl C71 methyl butyrate ([70] PCBM), phenyl C85 methyl butyrate ([85] PCBM), phenyl C61 butyl butyrate ([60] PCBB), phenyl C61 octyl butyrate ([60] PCBO)), an indene adduct of fullerene, a fullerene hydroxide, and a pyrrolidine derivative of fullerene.

(additives)

The lubricating oil composition in the present embodiment may contain additives in addition to the base oil and the fullerene within a range that does not impair the effects of the present embodiment.

The additive to be blended in the lubricating oil composition in the present embodiment is not particularly limited. Examples of the additives include commercially available antioxidants, viscosity index improvers, extreme pressure additives, detergent dispersants, pour point depressants, corrosion inhibitors, solid lubricants, oil improvers, rust inhibitors, anti-emulsifiers, defoaming agents, hydrolysis inhibitors, and the like. These additives may be used alone in 1 kind, or may be used in combination in 2 or more kinds.

The additive is preferably a compound having an aromatic ring because fullerene is easily dissolved.

Examples of the antioxidant having an aromatic ring include dibutylhydroxytoluene (BHT), Butylhydroxyanisole (BHA), 2, 6-di-tert-butyl-p-cresol (DBPC), 3-arylbenzofuran-2-one (intramolecular cyclic ester of hydroxycarboxylic acid), phenyl- α -naphthylamine, dialkyldiphenylamine, and benzotriazole.

Examples of the viscosity index improver having an aromatic ring include a hydrogenated product additive of polyalkylstyrene and a styrene-diene copolymer.

Examples of the extreme pressure additive having an aromatic ring include dibenzyl disulfide, allyl phosphate, allyl phosphite, amine salts of allyl phosphate, allyl thiophosphate, amine salts of allyl thiophosphate, naphthenic acid, and the like.

Examples of the cleaning dispersant having an aromatic ring include benzylamine succinic acid derivatives, alkylphenol amines, and the like.

Examples of the pour point depressant having an aromatic ring include a chlorinated paraffin-naphthalene condensate, a chlorinated paraffin-phenol condensate, and polyalkylstyrene.

Examples of the anti-emulsifier having an aromatic ring include alkyl benzene sulfonate.

Examples of the corrosion inhibitor having an aromatic ring include dialkyl naphthalene sulfonate.

The lubricating oil composition of the present embodiment can be used for industrial gear oil; hydraulic working oil; compressor oil; a refrigerator oil; cutting oil; plastic processing oil such as rolling oil, pressing oil, forging oil, drawing oil, blanking oil and the like; metal working oils such as heat treatment oil and electric discharge machining oil; sliding guide surface oil; bearing oil; antirust oil; heat medium oil, and the like.

(inspection method)

In the method for inspecting a lubricating oil composition according to the present embodiment, at least one of the drawn film length of the lubricating oil composition and the maximum path in the particle size distribution obtained by the dynamic light scattering method is measured. In the measurement of the particle size distribution, the particle size distribution of the fullerene and aggregate particles thereof dissolved or dispersed in the base oil was measured.

(measurement of film stretching Length)

The drawn film length of the lubricating oil composition is measured by a known method called a ring method or a torus method. Namely, the composition is prepared by mixing the following components in accordance with Japanese Industrial Standard JIS K2241: 2000, 7.3, by the surface tension test method.

Specifically, a ring suspended in parallel to a liquid (lubricating oil composition) to be measured is first sunk in the liquid, and then the ring is gradually pulled away in the vertical direction. At this time, a liquid film formed between the ring and the liquid surface generates a force that pulls the ring downward. This force, after showing a maximum value (i.e., surface tension), gradually decreases as the lift amount increases, and eventually becomes zero at the time when the liquid film is broken. Here, the moving distance of the ring until the liquid film is broken after the force of pulling down the ring shows the maximum value is defined as the pulled film length. In addition, "lifting" and "pulling down" of these rings indicate relative movement of the liquid with respect to the measurement object. For example, the ring may be fixed, and a stage on which a liquid to be measured is placed (hereinafter, may be simply referred to as "stage") may be moved.

In order to stably measure the drawn film length, the moving speed of the ring was set within a certain range. If the ring moves too fast, it breaks before the liquid film has stretched. On the other hand, if the moving speed of the ring is too slow, the components of the liquid film evaporate and break before the liquid film is completely stretched. In any case, the liquid film is broken and the liquid film is broken before the liquid film is stretched, and therefore the draw film length is determined to be short.

The optimum conditions for the moving speed of the ring vary depending on the characteristics of the liquid to be measured, but conditions such as the moving speed of the ring in which a representative sample is selected from among the samples to be measured and a measurement value of the longest stretched film length is obtained by performing a preliminary experiment using the following range as a standard are used.

The standard ring rising speed (platform falling speed) is preferably 0.01 mm/sec to 5.0 mm/sec, more preferably 0.1 mm/sec to 1.0 mm/sec. The dipping distance in the ring-shaped liquid is preferably 0.1mm to 50mm, more preferably 1mm to 10 mm.

(measurement of particle size distribution)

In the measurement of the particle size distribution of the lubricating oil composition, a dynamic light scattering method is used for the purpose of being suitable for measuring the particle size distribution in the nano-scale region. Specifically, the method of the examples described later was used.

From the obtained volume-based particle size distribution (also referred to as volume distribution), a particle size (referred to as "multipass") indicating the maximum value (frequency is the maximum) is determined.

In the method for inspecting a lubricating oil composition according to the present embodiment, at least one of the drawn film length of the lubricating oil composition and the maximum diameter of the particle size distribution obtained by the dynamic light scattering method is measured, and a lubricating oil composition whose measured value is within a set range (a certain range) is determined as a pass, and a lubricating oil composition whose measured value is outside the set range is determined as a fail. Thus, the lubricating oil composition was screened.

The predetermined range of the measured value is set to be within a desired range of the friction coefficient based on the relationship between the friction coefficient and the drawn film length or the maximum diameter as shown in examples described later.

In the method for inspecting a lubricating oil composition according to the present embodiment, it is preferable to measure the film length of the lubricating oil composition and the maximum path of the particle size distribution obtained by the dynamic light scattering method, and select a lubricating oil composition in which both of the measured values fall within a predetermined range. By measuring the drawn film length and the maximum path in this manner, the lubricating oil composition in which the 2 measured values are within the set range is screened, and the screening accuracy can be further improved. As a result, the friction characteristics of the lubricating oil composition can be more stably reproduced.

In addition, the method for inspecting the lubricating oil composition of the present embodiment may measure the density, dynamic viscosity, viscosity index, pour point, total oxidation, and the like of the lubricating oil composition as described in non-patent document 1.

According to the method for inspecting a lubricating oil composition of the present embodiment, even in the case of a lubricating oil composition containing fullerene, the friction characteristics can be stably reproduced by using a method that is relatively easy to measure, such as at least one of the length of the drawn film of the lubricating oil composition and the diameter distribution of the particles obtained by the dynamic light scattering method.

[ method for producing lubricating oil composition ]

The method for producing a lubricating oil composition of the present embodiment includes the steps of: the lubricating oil compositions obtained by mixing the base oil and the fullerene are screened by the method for testing a lubricating oil composition according to the present embodiment.

The method for producing a lubricating oil composition of the present embodiment specifically includes the steps of:

(1) a step of mixing a base oil with fullerene, dissolving the fullerene dissolved component in the base oil, and optionally subjecting the mixture to filtration, heat treatment, or the like to obtain a lubricating oil composition as a mixture of the base oil and the fullerene (hereinafter referred to as "pretreatment step"); and

(2) a step (hereinafter, referred to as "inspection step") of measuring physical properties (film length and/or maximum path) of the lubricating oil composition, digitizing the measured values, determining that the lubricating oil composition is acceptable when each measured value is within a predetermined range, determining that the lubricating oil composition is unacceptable when each measured value is outside the predetermined range, and screening the lubricating oil composition.

The method for producing a lubricating oil composition of the present embodiment may further include the following steps, if necessary:

(3) a step of mixing the lubricating oil compositions produced in a plurality of different production lots so as to be able to pass the screening in the "inspection step", thereby obtaining a new lubricating oil composition (hereinafter referred to as "post-treatment step").

The method for producing the lubricating oil composition of the present embodiment is described in detail below.

(pretreatment step)

The fullerene as a raw material is charged into the base oil and subjected to a dispersion treatment using a dispersing means such as a stirrer for 1 to 48 hours at a temperature near room temperature or, if necessary, while being heated.

Examples of the dispersing means for dispersing the fullerene in the base oil include a stirrer, an ultrasonic dispersing device, a homogenizer, a ball mill, a bead mill, and the like.

This operation yields a liquid in which fullerene is dissolved or dispersed in the base oil (sometimes referred to as "fullerene solution").

The amount of the fullerene to be charged may be such that the concentration of the fullerene in the fullerene solution becomes a desired concentration. In the pretreatment step, when a step of removing insoluble components, which will be described later, is provided, the amount of fullerene to be removed in the step is also taken into consideration, and the amount of fullerene to be added is increased. Generally, the fullerene concentration in the fullerene solution is in the range of 1 mass ppm to 1 mass%.

Further, a fullerene solution having a concentration higher than a desired concentration can be obtained, and the fullerene solution having a desired concentration can be obtained by diluting the fullerene solution with a base oil.

The fullerene solution obtained as described above can be used as it is as a lubricating oil composition.

Further, it is preferable that a step of removing insoluble components is provided in the pretreatment step, and the fullerene solution from which the insoluble components have been removed is used as the lubricating oil composition. The step of removing the insoluble component is preferably provided in the pretreatment step after the dispersion treatment of dispersing the fullerene in the base oil.

Examples of the step of removing the insoluble component include (1) a removal step using a membrane filter, (2) a removal step using a centrifugal separator, and (3) a removal step using a membrane filter and a centrifugal separator in combination. Among these removal steps, from the viewpoint of filtration time, (1) a removal step using a membrane filter is preferable when a small amount of the lubricating oil composition is obtained, and (2) a removal step using a centrifugal separator is preferable when a large amount of the lubricating oil composition is obtained.

In the pretreatment step, particularly when the fullerene solution is heated, it is preferable to perform the pretreatment in a non-oxidizing atmosphere. For example, it is preferable that the inside of a container containing the fullerene solution is replaced with an inert gas such as nitrogen or argon, or the fullerene solution in the container is further bubbled with an inert gas so that the fullerene solution and the inert gas are in an equilibrium state.

(inspection step)

In the method for producing a lubricating oil composition of the present embodiment, the inspection step is a step of screening the lubricating oil composition by the method for inspecting a lubricating oil composition of the present embodiment.

(post-treatment Process)

At least one of the measurement of the drawn film length and the measurement of the particle size distribution is performed for each of the lubricating oil compositions produced by a plurality of different production lots. Thus, at least one of the film length and the particle size distribution of the lubricating oil composition in the production lot is grasped, and the lubricating oil compositions can be classified by these measurement values.

By classifying the lubricating oil compositions, the following effects are obtained.

(1) It is possible to exclude at least one of the most multipath of the drawn film length and the particle size distribution from being an unacceptable lubricating oil composition.

(2) By mixing a plurality of different lubricating oil compositions included in a range in which at least one of the most multipath of the drawn film length and the particle size distribution fails, a lubricating oil composition that can be qualified can be recovered.

(3) By mixing a plurality of different lubricating oil compositions contained in ranges that are qualified for at least one of the most multipath of the drawn film length and particle size distribution, a new lubricating oil composition can be obtained.

As described above, according to the method for producing a lubricating oil composition of the present embodiment, even in the case of a lubricating oil composition containing fullerene, a lubricating oil composition with less variation in friction characteristics among production lots can be obtained by using a method in which measurement is relatively easy, such as measurement of at least one of the drawn film length of the lubricating oil composition and the maximum diameter in the particle size distribution obtained by the dynamic light scattering method.

The friction coefficient of a lubricating oil composition is important as an item for evaluating the friction characteristics and the lubrication characteristics of the lubricating oil composition. However, the friction coefficient measurement is laborious.

The present inventors have found that the maximum diameter in the drawn film length of the lubricating oil composition and the particle size distribution obtained by the dynamic light scattering method is a numerical value having a correlation with the friction coefficient of the lubricating oil composition as described below, and that the maximum diameter can be used as an index of the friction coefficient of the lubricating oil composition. That is, if the film-drawing length of the lubricating oil composition and/or the value of the above-mentioned multipath is within a specific range, it can be said that the friction coefficient of the lubricating oil composition is within a specific range corresponding to the film-drawing length and/or the value of the above-mentioned multipath.

The measurement of the drawn film length and/or the above-mentioned maximum path of the lubricating oil composition is simple as compared with the measurement of the friction coefficient. Therefore, by using the film length of the lubricating oil composition and/or the measured value of the maximum path as an index of the friction coefficient, the friction coefficient of the lubricating oil composition can be easily and efficiently evaluated without performing a laborious measurement of the friction coefficient. Further, the evaluation method for evaluating the friction coefficient of a lubricating oil composition using the film-drawing length of the lubricating oil composition and/or the measured value of the above-mentioned maximum path is useful because it is not necessary to measure the friction coefficient and it can be easily judged whether or not the lubricating oil composition has an appropriate friction coefficient depending on the application or the like.

While the preferred embodiments of the present invention have been described in detail, the present invention is not limited to the specific embodiments. The present invention can be modified and changed in various ways within the scope of the gist of the present invention described in the scope of the claims.