JPH07270397A - Oxidation stability evaluation method and apparatus - Google Patents

Abstract

(57) [Summary] [Objective] To provide an oxidation stability evaluation method and an apparatus thereof, which can easily and quickly evaluate the oxidation life of a sample without requiring a special analysis device. [Structure] First, the sample is held at a predetermined temperature. here,
If necessary, the sample is subjected to oxidation promotion treatment. For example,
Blow oxygen into the sample or stir the sample. In this state, at least one of the temperature, odor intensity, and transmittance of the sample is measured, and the oxidation life of the sample is evaluated from the measurement result. For example, with respect to the temperature and odor intensity of the sample, when the sample reaches the oxidative life, the temperature and odor intensity rapidly increase, so the time from the start of measurement to the inflection point is measured, and based on this time, the sample Evaluate oxidative life.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oxidation stability evaluation method and apparatus for easily and quickly evaluating the oxidation life of a sample, for example, an oil and fat sample.

[0002]

BACKGROUND ART Conventionally, JIS K2514 (ISOT… Indiana Sti) has been used to evaluate the oxidation stability of oil and fat samples, especially lubricating oils.
rring Oxidation Stability Test, TOST… Turbin oil Ox
idation Stability Test, RBOT ... Rotary Bomb Oxidation
Stability Test) and IOT (Indiana Oxidation Stabi
The oxidative stability test method defined by the Lity Test) is widely used. These oxidation stability test methods consist of holding a sample container containing sample oil, catalyst, etc. in a constant temperature bath, sampling the sample oil at regular intervals, and changing properties such as viscosity ratio and total acid value increase. This is a method of analyzing deterioration and grasping the deterioration situation.

[0003]

However, in the above-mentioned conventional oxidation stability test method, it is necessary to collect the sample oil and analyze the property changes at regular time intervals, which is troublesome and requires various analyzers. I need. Moreover, when looking at the deterioration status over time, especially with engine oil, etc., the gradual value increases only, and a clear inflection point cannot be obtained, and evaluation is often made when the control limit is exceeded. There was a problem that it took time.

It is an object of the present invention to solve such conventional problems and to easily and quickly evaluate the oxidation life of a sample, that is, the oxidation stability, without the need for a special analyzer. An object of the present invention is to provide an oxidation stability evaluation method and an apparatus therefor.

[0005]

The oxidation stability evaluation method of the present invention holds a sample at a predetermined temperature and measures at least one of the temperature, odor intensity and transmittance of the sample, It is characterized in that the oxidation life of the sample is evaluated from the result. Here, the sample may be subjected to an oxidation promoting treatment. Examples of the oxidation promoting treatment include an oxygen blowing treatment for blowing oxygen into the sample and a sample stirring treatment for stirring the sample.

The oxidation stability evaluation apparatus of the present invention comprises a sample container containing a sample therein, temperature holding means for holding the sample in the sample container at a predetermined temperature, temperature, odor intensity and transmittance of the sample. It is characterized by comprising a measuring means for measuring at least one of the above and a recording means for recording a result measured by the measuring means. Here, the sample container may be provided with an oxidation promoting means. Examples of the oxidation promoting means include an oxygen blowing means for blowing oxygen into the sample and a sample stirring means for stirring the sample.
The measuring means is at least one of a temperature sensor and an odor intensity sensor, or a transmittance sensor.

[0007]

Function: To evaluate the oxidation stability of a sample, the sample is kept at a predetermined temperature. Here, if necessary, the sample is subjected to an oxidation promoting treatment. For example, oxygen is blown into the sample or the sample is stirred. At this time, these processes may be performed simultaneously. In this state, at least one of the temperature, odor intensity, and transmittance of the sample is measured, and the oxidation life of the sample is evaluated from the measurement result. For example,
When measuring the temperature and odor intensity of a sample, when the sample reaches its oxidation life, the temperature and odor intensity rise sharply, so the time from the start of measurement to the inflection point at which the temperature and odor intensity changes rapidly is measured. The oxidation life of the sample is evaluated based on the measured time. In addition, the color of the sample is light (for example, AST
If the M color is 4.0 or less), the transparency of the sample, which decreases with time at the beginning of the measurement, changes in the opposite direction at about the same time as the time to the inflection point obtained by measuring the temperature and odor intensity. It is also possible to evaluate the oxidation life of the sample based on the measured time up to the inflection point because it changes abruptly, that is, the transmittance increases.

[0008]

An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 shows an oxidation stability evaluation apparatus of the present invention. The apparatus comprises a sample container 10 containing a sample 1 therein, a constant temperature bath 20 as a temperature holding means for holding the sample 1 in the sample container 10 at a predetermined temperature, and the sample 1
Temperature sensor 30 that measures the temperature of the
Recording device 3 for displaying and recording temperature data measured at 0
1, a odor sensor 40 for measuring the odor intensity of the sample 1 in the sample container 10, and a recording device 41 for displaying and storing the odor intensity data measured by the odor sensor 40. Here, each of the sensors 30 and 40 is a measuring unit that measures the temperature and odor intensity of the sample 1,
Reference numerals 1 and 41 constitute recording means for recording the results measured by the sensors 30 and 40.

The sample container 10 comprises a container body 11 and a lid 12 for closing the upper end opening of the container body 11.
Inside the container body 11, the sample 1 is stored, and if necessary, a metal catalyst 2, for example,
A coiled copper wire or the like is housed. In addition,
Regarding the size of the container body 11, since the odor sensor 40 is used, the ratio of the gas phase portion / liquid phase (sample) portion is relatively small, that is, the gas phase portion is relatively smaller than the liquid phase portion. Size is preferred. This is because the time until the odorous component is saturated in the gas phase due to the life of the sample becomes shorter when the gas phase portion is smaller, so that the odor sensor 40 can quickly detect. The gas phase / liquid phase ratio is preferably 0.5 to 5. The lid 12 is provided with a gas suction pipe 40A for the temperature sensor 30 and the odor sensor 40, and is provided with an oxidation promoting means 13. The oxidation promoting means 13 has an oxygen blowing tube 14 as an oxygen blowing means for blowing oxygen into the bottom of the sample 1, and a stirring blade 16 at the tip.
And a stirring rod 15 as a sample stirring means for stirring the sample 1 while rotating.

The constant temperature bath 20 comprises a bath main body 21 and a lid 22 for closing the upper end opening of the bath main body 21. The bath main body 21 includes a bath portion 23 including an air bath or a liquid bath.
Is formed (the liquid bath is shown in the figure), and its bath part 2
A temperature control unit (not shown) for controlling the temperature inside 3 to a predetermined temperature is provided. Here, it is desirable that the temperature can be controlled to a test temperature of ± 0.5 ° C, preferably ± 0.1 ° C. The lid 22 is provided with a holding hole 24 for holding the container body 11 of the sample container 10 in a bath 23.

As the temperature sensor 30, various thermometers such as a liquid thermometer and a resistance thermometer, or a thermocouple can be used. It is desirable that the temperature change of the sample 1 can be detected at about 1 ° C, preferably about 0.5 ° C.
As the odor sensor 40, various odor sensors such as a metal oxide semiconductor type and a bilayer crystal oscillation type can be used. Gas suction pipe 40A for guiding the target gas to the odor sensor 40
Is formed in a predetermined length by a thin tube made of glass, metal, plastic, or the like, and its tip is exposed to the gas phase portion in the sample container 10 through the lid 12. in this case,
You may install so that the front-end | tip of 40 A of gas suction pipes may face the position near the opening part on the outer side of the cover 12.

Next, the measuring method of this embodiment will be described. The sample 1 and, if necessary, the metal catalyst 2 are placed in the container body 11 of the sample container 10. The amount of the sample 1 accommodated should be 10 in consideration of various conditions such as temperature control and detection sensitivity of various sensors.
About 300 ml is preferable. When Sample 1 is an additive (including viscous, solid sample, etc.), it may be appropriately diluted with a base material such as lubricating base oil for measurement. After this,
The upper end opening of the container body 11 is closed by the lid 12. An oxygen blowing pipe 14 and a stirring rod 15 are attached to the lid body 12 in advance or thereafter. The sample container 1 is placed in the constant temperature bath 20 which is kept at the test temperature in advance.
Set to 0. The gas suction tube 40A of the temperature sensor 30 and the odor sensor 40 is inserted into the lid 12 of the sample container 10.

Oxygen is blown into the sample 1 through the oxygen blowing tube 14.
Blow into. At this time, you may dilute with an inert gas and use it as needed. As for the blowing method, it is desirable to blow fine bubbles in order to accelerate the oxidation or reduce the influence on the temperature sensor 30. Also,
It is preferable to blow from the bottom of the sample container 10. The recording devices 31 and 41 are operated. Each recording device 3
1 and 41, the temperature and odor intensity data measured by the sensors 30 and 40 are displayed and recorded. When the sample 1 reaches the oxidative life, the temperature and odor intensity data change abruptly, that is, rise, so the time from the start of measurement to the inflection point where the temperature and odor intensity data changes abruptly is measured, The time is evaluated as the oxidation lifetime of Sample 1.

Therefore, according to this embodiment, the temperature and the odor intensity of the sample 1 are measured by the temperature sensor 30 and the odor sensor 40 while the sample 1 is kept at a predetermined temperature.
Since the oxidation life of the sample 1 was evaluated from this measurement result, the sample 1 was evaluated without the need for a special analyzer.
It is possible to easily and quickly evaluate the oxidation life of the.
That is, when the temperature and odor intensity of the sample 1 are measured, the temperature and the odor intensity rapidly increase when the sample 1 reaches the oxidation life. Therefore, the time from the start of measurement to the inflection point is measured. Simply set the time as the sample oxidation life time,
It is possible to easily and quickly evaluate and compare the oxidation lives of the samples themselves or between the samples. Also, sample 1
Oxygen is blown into the sample, and the oxidation promoting process of stirring the sample 1 is performed. Therefore, the time from the start of measurement to the inflection point can be shortened. That is, the measurement time can be shortened.

Here, the measurement results of this embodiment are
The explanation will be made in comparison with the measurement results by the JIS method. Fig. 2 shows that the temperature of the constant temperature bath was kept at 165.5 ° C ± 0.1 ° C, and engine oil was used as sample 1 under the JIS method (I
It is the result of measuring the viscosity ratio and the total acid value increase amount by analyzing the sample at regular intervals by SOT). FIG. 3 shows FIG.
Under the same conditions as described above, according to the method of the present example, sample 1
It is the result of measuring the temperature and the odor intensity of. As can be seen from these figures, when measuring engine oil etc. by the JIS method (ISOT), if the viscosity ratio and total acid value increase amount are analyzed by analyzing at regular intervals, only the gradual value increases,
You cannot get a clear inflection point. On the other hand, when the method of this example is used for measurement, a clear inflection point is obtained, and the oxidation life can be quickly evaluated as the oxidation life time without analyzing the oxidized oil.

The following seven different oils (A, B,
Table 1 shows the results of measuring the time until the oxidation life of C, D, E, F, G oils) according to the JIS method (ISOT) and the method of this example. In the JIS method (ISOT), the time until the total acid value increase reaches the control limit of 5 mgKOH / g, and in the method of this example, the time until reaching the inflection point is the time until reaching the oxidation life. It was measured. As is clear from Table 1, the JIS method is more effective in the case of the method of this embodiment.
It can be seen that the time to reach the oxidation life can be significantly shortened as compared with the case of (ISOT). In other words, the JIS method only measures the properties of the sample at regular intervals, and there is no particular provision for determining the oxidation life (criterion criteria for the end of the test). Therefore, the life of the oil is usually reached when the measured value of the property reaches the control limit value. However, in this embodiment,
In addition to accelerating the oxidation, the oxidation life can be judged at a clear inflection point, so that it is possible to make the judgment in a short time without making unnecessary measurement, and the judgment can be facilitated.

[0017]

[Table 1]

The color of the sample 1 is light (for example, AS
If the TM color is 4.0 or less), as shown in FIG. 4, the transparency of the sample 1, that is, the transmittance (%), which decreases with the passage of time at the beginning of measurement, can be obtained by the temperature sensor 30 and the odor sensor 40. At the same time as the inflection point, it rises sharply. Therefore, for these samples, in addition to the sensors 30, 40, or these sensors 30, 4
In place of 0, a transmittance sensor as a measuring means for measuring the transparency of the sample 1 is provided, and the time until the point where the transmittance data measured by this transmittance sensor changes abruptly is evaluated as the oxidation life time. Is also possible. Incidentally, as the transmittance sensor, while irradiating the sample with light, the transmittance of the light from the received light amount of the light transmitted through the sample,
That is, the transparency may be measured.

Further, as shown in FIG.
The change rate is obtained by differentiating the measurement data of the sensors 30 and 40 for measuring the odor intensity and the transmittance sensor 50 for measuring the transmittance by a differentiator (differentiating means) 61, and a comparator (comparing means).
In 62, when the rate of change is compared with the preset value and the rate of change exceeds the preset value, the measurement is ended by an alarm (notifying means) 63 such as a buzzer or a display, and the effect is visually or visually detected. In addition to the notification, each recording device 31,
It is also possible to command 41 or the like to display the oxidation life time. This is convenient because labor saving and automation can be achieved. At this time, the comparator 62 compares with the set value and also determines whether or not the value exceeds the set value, that is, the oxidation life, and therefore, it can be said that the comparator 62 also functions as a comparison and determination unit. The comparison / determination means may be composed of a personal computer or the like.

In the above embodiment, the temperature of the sample 1
Although the sensors 30 and 40 for measuring the odor intensity are provided respectively, only one of the sensors 30 and 40 may be provided.
Further, the oxidation promoting treatment (oxygen blowing treatment and sample stirring treatment) is not always necessary and may be performed as necessary.

[0021]

As described above, according to the oxidation stability evaluation method and apparatus of the present invention, at least one of the temperature, odor intensity and transmittance of the sample is measured, and the oxidation life of the sample is evaluated from the measurement result. As a result, the oxidation life of the sample can be evaluated easily and quickly without the need for a special analyzer.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of an oxidation stability evaluation apparatus according to the present invention.

FIG. 2 is a diagram showing measurement results by a conventional test method (JIS method).

FIG. 3 is a diagram showing measurement results by temperature and odor in the evaluation method of the present invention.

FIG. 4 is a diagram showing a measurement result based on transmittance in the evaluation method of the present invention.

FIG. 5 is a diagram showing a modified example of the oxidation stability evaluation apparatus according to the present invention.

[Explanation of symbols]

 1 sample 10 sample container 13 oxidation promoting means 14 oxygen blowing tube as oxygen blowing means 15 stirring rod as sample stirring means 20 constant temperature bath as temperature holding means 30 temperature sensor 40 as measuring means 40 odor sensor as measuring means 50 measurement Transmittance sensor as a means

Claims (7)

[Claims] 1. A method of holding a sample at a predetermined temperature, measuring at least one of temperature, odor intensity, and transmittance of the sample, and evaluating the oxidation life of the sample from the measurement result. Oxidation stability evaluation method. 2. The oxidation stability evaluation method according to claim 1, wherein the sample is subjected to an oxidation promoting treatment. 3. The oxidation stability evaluation method according to claim 2, wherein the oxidation promoting treatment is a treatment including at least one of an oxygen blowing treatment for blowing oxygen into the sample and a sample stirring treatment for stirring the sample. An oxidative stability evaluation method characterized by the above. 4. A sample container containing a sample therein, and temperature holding means for holding the sample in the sample container at a predetermined temperature,
Oxidation stability evaluation device comprising: a measuring unit that measures at least one of the temperature, the odor intensity, and the transmittance of the sample; and a recording unit that records the result measured by the measuring unit. . 5. The oxidation stability evaluation apparatus according to claim 4, wherein the sample container is provided with an oxidation promoting means. 6. The oxidation stability evaluating apparatus according to claim 5, wherein the oxidation promoting means includes at least one of an oxygen blowing means for blowing oxygen into the sample and a sample stirring means for stirring the sample. An oxidation stability evaluation device characterized by: 7. The oxidation stability evaluation device according to claim 4, wherein the measuring means is at least one of a temperature sensor and an odor intensity sensor, or a transmittance sensor. Characteristic oxidation stability evaluation device.