JP3221209B2 - Oil content measurement method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil content measuring method, and more particularly to a method for judging the degreasing effect of press oil used in a shadow mask press process of a color cathode ray tube, measuring a trace amount of oil in factory drainage, and measuring a polyethylene bag. Provided is a method useful for measurement of various oil components, such as analysis of a lubricant and measurement of the adhesion amount of silicone oil used in a semiconductor device manufacturing process.

[0002]

2. Description of the Related Art In recent years, in the measurement of oil content, since an organic substance such as oil always has a C--H bond, the specific absorption intensity near the infrared region of 2,920 cm ^-1 of the C--H bond is measured and quantified. A method of doing so has been implemented. In this method, carbon tetrachloride having no CH bond is used for elution of the oil component.

[0003] A conventional oil content measuring method will be described below. FIG. 7 shows a conventional infrared spectrometry cell used for oil measurement. In FIG. 7, reference numeral 61 denotes a cell main body, which comprises a glass cylindrical body 63 provided with an opening 62 and window plates 64 and 65 that transmit infrared light and hermetically seal both ends thereof. Have been. 66 is a lid made of glass,
3. The cell main body 61 is hermetically sealed by fitting it into the opening 62 provided in the device 3.

In the oil measuring cell having such a structure,
The carbon tetrachloride in which the oil is dissolved is put into the cell main body 61 through the opening 62, the lid 66 is placed in the opening 62, and then the cell main body 61 is passed through the two window plates 64 and 65 that are inert to infrared light.
Through which infrared light is transmitted to measure the specific absorption intensity of the C—H bond of the oil component.

[0005]

In this conventional method,
Carbon tetrachloride having a large ozone depletion potential is used as the oil solvent. Carbon tetrachloride is required to be completely abolished by the year 2000 in the Montory All Protocol adopted in 1987, and is a substance that must be promptly worked to reduce its use in terms of environmental protection.

[0006] The present invention does not use such halogenated carbon which must be avoided for environmental protection.
It is intended to provide a method capable of measuring oil content.

[0007]

In order to achieve this object, an oil content measuring method of the present invention comprises a plurality of types of volatile organic solvents, and the lowest azeotropic point is lower than the boiling point of each of these volatile organic solvents. The oil is dissolved in the mixed solvent, the mixed solvent is removed by utilizing the difference in boiling point between the mixed solvent and the oil, the oil is selectively taken out, and the oil content is quantitatively determined from the infrared absorption intensity of the CH bond at around 2,920 cm ^-1. Is the way.

[0008]

In the method of the present invention, carbon tetrachloride is not required by using a mixed solvent comprising a plurality of types of volatile organic solvents and having a minimum azeotropic point lower than the boiling point of each of these volatile organic solvents as a solvent for the oil component. Becomes In the present invention, the organic solvent has an absorption band of C—H bonds, but the solvent is removed by utilizing the boiling point difference between the oil and the mixed solvent, and the C—H bonds of the organic solvent affect the measurement result. There is no danger.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In an azeotropic solvent composed of a plurality of types of volatile organic solvents, the ratio of the amount of evaporation changes by changing the mixing ratio of the constituent volatile organic solvents. Therefore, by adjusting the mixing ratio of the azeotropic mixed solvent so that the volatile organic solvent having a low boiling point is finally evaporated, the time for removing the solvent is greatly reduced. Thereby, the time required for the measurement is significantly reduced.

For example, taking as an example a binary mixed solvent of hexane as an aliphatic hydrocarbon solvent and acetone as a ketone solvent, the relationship between the composition ratio of this mixed solvent and the boiling point is shown in FIG. Become like That is, hexane is 1
The boiling point is 69 ° C. when the amount is 00% by weight, and the boiling point decreases as the value of the composition ratio of acetone increases.
C)), the boiling point increases as the weight ratio of acetone increases, and 100% by weight of acetone
To 56 ° C. From this, the use of a mixed solvent having an azeotropic point or a composition ratio substantially equal to the azeotropic point enables the solvent to be removed most effectively, and allows the oil agent to be measured to be extracted. That is, when hexane and acetone are mixed at a weight ratio of about 41:59, the mixed solvent exhibits a minimum azeotropic point of 49 ° C., and is easily removed by heating to 49 ° C. or slightly higher. Is done.

FIG. 6 shows how hexane, acetone, and a hexane / acetone azeotrope are evaporated and reduced when they are kept at room temperature (20 ° C.). From this, it can be seen that the azeotropic mixed solvent of hexane and acetone is more remarkable in evaporation loss than any of hexane and acetone.

The minimum azeotropic point of a mixed solvent of hexane and acetone is lower than the boiling point of almost all oil components, and it is possible to measure oil components that evaporate at low temperatures, which has been very difficult to measure until now. And even if the ratio of acetone becomes a value slightly larger than the azeotropic mixture ratio, the solvent can be removed at a boiling point of acetone (56 ° C.) or lower.

[0013] As shown in Table 1 below, hexane and acetone have different properties with hydrocarbon-based oils and silicone-based oils, although each of hexane and acetone is dissolved alone. That is,
Hexane dissolves hydrocarbon-based oils, but it is difficult to dissolve silicone-based oils alone. On the other hand, acetone alone dissolves a silicone-based oil, although it has a relatively low solubility in a hydrocarbon-based oil.

By using a mixed solvent of hexane and acetone, each characteristic is complemented, and the number of objects to be measured is greatly increased.

[0015]

[Table 1]

In addition to hexane, pentane,
2-methylbutane, or 2-methylpentane, in addition to acetone, methyl ethyl ketone, 2-pentanone, 3-pentanone, 2-hexane,
Alternatively, a similar result can be obtained by using a mixed solvent with the use of methyl isobutyl ketone.

An embodiment of the method of the present invention will be described below with reference to the drawings. First Embodiment FIGS. 1 to 3 are views for explaining a method according to a first embodiment of the present invention. FIG. 1 is a view showing an example of the structure of an oil extraction device, and FIGS. FIG. 4 is a sample preparation process diagram for oil content measurement.

In FIG. 1, reference numeral 1 denotes a thermostat, which contains a mixed solvent 2 of hexane and acetone. Reference numeral 3 denotes a heating device for heating the constant temperature bath 1 to maintain the mixed solvent 2 at a temperature not lower than the minimum azeotropic point and vaporize it. 4
Is a hexane introduction pipe, and 5 is an acetone introduction pipe, and hexane and acetone are replenished into the thermostat 1 by opening the valves 6 and 7, respectively. 8 is a sample processing chamber, 9 is a solvent vapor pipe,
A valve 10 is provided, and by opening it, a solvent vapor is introduced from the thermostat 1 into the sample processing chamber 8. Reference numeral 11 denotes a heating device which is disposed so as to cover the solvent vapor pipe 9, and is for heating the solvent vapor pipe 9 to prevent the mixed solvent from condensing. Reference numeral 12 denotes a ceramic container for storing an oil to be quantified, which is disposed in the sample processing chamber 8. Reference numeral 13 denotes a heating device for heating the ceramic container 12 to maintain the temperature at a temperature lower than the boiling point of the oil component to be measured and higher than the boiling point of the mixed solvent. Reference numeral 14 denotes a sample support made of stainless steel, which penetrates into the upper part of the sample processing chamber 8, and is disposed so that the tip portion is located above the ceramic container 12. Reference numeral 15 denotes a sample to which the oil to be measured adheres, which is attached near the tip of the sample support 14. A cooling device 16 is connected to the other end portion of the sample support 14 protruding outside the sample processing chamber 8 and cools the sample 15 through the sample support 14 to condense the mixed solvent vapor. 17 is a nitrogen gas inlet pipe, 18
Is a nitrogen gas discharge pipe for introducing and discharging nitrogen gas into the sample processing chamber 8 by opening and closing valves 19 and 20. Reference numeral 21 denotes a pressure adjusting valve for adjusting the pressure in the sample processing chamber 8. Reference numeral 22 denotes a gas chromatography for detecting the component ratio of the solvent vapor in the thermostat 1. Reference numeral 23 denotes a control device equipped with a microcomputer, which controls the opening and closing of the valves 6 and 7 according to the output signal of the gas chromatography 22, replenishes hexane and acetone into the thermostat 1, and azeotropically mixes the mixed solvent 2. Keep at mixing ratio.

In the oil extractor constructed as described above, first, the sample processing chamber 8 is opened, the sample 15 is attached to the tip of the sample support 3, and then the sample processing chamber 8 is closed. Replace air with nitrogen gas. That is,
By opening the valves 19 and 20, nitrogen gas is introduced into the sample processing chamber 8 from the nitrogen gas introducing pipe 6, and air in the sample processing chamber 8 is discharged from the nitrogen gas discharging pipe 18. on the other hand,
The mixed solvent 2 of hexane and acetone in the thermostatic layer 1 is heated by the heating device 3 at a temperature higher than its boiling point to be vaporized. When the inside of the sample processing chamber 8 is replaced with nitrogen gas, the valve 10 is opened, and the mixed solvent vapor is introduced into the sample processing chamber 8 through the solvent vapor pipe 9 covered with the heating device 11.
The pressure in the sample processing chamber 8 is adjusted by the pressure adjusting valve 21 and kept constant. The sample support 14 is cooled by the cooling device 16, and the sample 15 attached to the tip is also cooled. The vapor of the mixed solvent in the sample processing chamber 8 is cooled and condensed by coming into contact with the cooled sample 15, turns into a liquid, and dissolves organic matter such as oil adhering to the sample 15. The extracted organic matter is dropped together with the liquefied mixed solvent into the ceramic container 12 disposed below the mixed solvent. Since the ceramic container 12 is maintained at a predetermined temperature by the heating device 13, the azeotropic solvent having a low boiling point volatilizes immediately, and the extracted organic matter having a higher boiling point remains in the ceramic container 12.

After the solvent has been completely removed, as shown in FIG.
As shown, the potassium bromide powder is placed in the ceramic container 12.
31 and put in a ceramic container 12 with a spatula 32.
Stir to scrape off the bottom of. Potassium bromide powder
The wall surface of the ceramic container 12 due to the frictional force of the crystal 31
Extracted organic matter 33 attached to the surface is scraped off and potassium bromide is removed.
Disperse in the system powder 31. Then, as shown in FIG.
Then, the extracted organic matter 33 is added to the main body 42 of the pressurized tablet press 41.
Put in the state of being dispersed in potassium bromide powder 31, and add
Infrared spectroscopy measurement by pressing the lid 43 of the tablet press
Make tablets for use. About this tablet for infrared spectrometry,
2920 cm by known infrared spectroscopy ^-1Nearby
The oil content is determined by measuring the absorption strength of the CH bond.
Quantify.

The mixed solvent 2 in the constant temperature layer 1 is rapidly vaporized, and if left as it is, the component ratio changes in a relatively short time. In the present embodiment, the component ratio of the mixed solvent vapor in the thermostatic layer 1 is detected by the gas chromatography 22, and the equilibrium state of the component ratio is monitored by the controller 23. When it is detected that the equilibrium state has collapsed, the controller 23 adjusts the degree of opening and closing of the valves 6 and 7 according to the amount of evaporation,
The supply amounts of hexane and acetone are controlled, and the mixed solvent 2 is always maintained at the theoretical azeotropic mixing ratio.

[Second Embodiment] A second embodiment of the present invention will be described below with reference to FIG.

FIG. 4 is a view showing the structure of an apparatus used for extracting oil and organic substances in a second embodiment of the present invention. In FIG. 4, reference numeral 41 denotes a heating device with a temperature control mechanism, and a local exhaust device 42 is disposed above the heating device. Reference numeral 43 denotes a petri dish made of glass for boiling a sample, in which a mixed solvent 45 of acetone and hexane is put.
Reference numeral 46 denotes a sample to be measured.

First, the heating device 41 is energized to generate heat,
Keep at a predetermined temperature. Heating device 4 with temperature control mechanism
A sample boiling glass petri dish 43 is placed on 1, and a sample 46 cut or broken into an appropriate size is put into the sample boiling petri dish 43. Then, a mixed solvent 45 of acetone and hexane is added in such an amount that the sample 46 is sufficiently immersed, and the mixture is heated and eluted at a fixed temperature for a fixed time. After a certain period of time, the sample 46 is taken out of the sample boiling petri dish 43 and heating is continued. Petri dish 43 for boiling sample
When the amount of the solvent 45 gradually decreases, the solvent 45 is transferred to a ceramic container, and the solvent is completely removed at room temperature. After removing the solvent, potassium bromide powder is added, and a tablet for infrared spectrometry is prepared in the same procedure as in the first example, and the oil content is determined by measuring the absorption intensity of the CH bond using the tablet. .

According to the present embodiment, by using a binary solvent mixture of hexane and acetone, even a silicone oil which has been difficult to dissolve with hexane alone can be used.
In addition, it becomes possible to dissolve even high-molecular oil which is difficult to dissolve in acetone alone, so that the restriction on the object to be measured is remarkably relieved and various oil contents can be easily measured. The removal of the solvent is also very easy because the mixed solvent has a low boiling point.

The method of the present invention can be used, for example, to judge the degreasing effect of press oil used in the shadow mask pressing step of a color cathode ray tube, to measure a trace amount of oil in factory wastewater, to analyze the lubricant in a polyethylene bag, Measurement of the amount of silicone oil used in the manufacturing process of the device,
The present invention can be applied to extraction and measurement of a lubricant used in molding a synthetic resin or the like.

[0027]

According to the method of the present invention, a mixed solvent comprising a plurality of types of volatile organic solvents and having a minimum azeotropic point lower than the boiling point of each of these volatile organic solvents is used as a solvent for the oil component. This eliminates the need for carbon tetrachloride, which has been widely used, and enhances environmental safety. And, although the organic solvent has a C—H bond absorption band, since the boiling point of the mixed solvent is low, the solvent can be easily removed by utilizing the boiling point difference with the oil component, and the organic solvent The C—H bond does not affect the measurement result.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of the structure of an oil extractor used in a method according to a first embodiment of the present invention.

FIG. 2 is a sample preparation process diagram for measuring oil content in the method according to the first embodiment of the present invention.

FIG. 3 is a sample preparation process diagram for measuring oil content in the method of the first embodiment of the present invention.

FIG. 4 is a diagram showing the structure of an apparatus used for extracting oil and organic matter in the method according to the second embodiment of the present invention.

FIG. 5 is a diagram showing the relationship between the composition ratio of a binary mixed solvent of hexane and acetone and the boiling point.

FIG. 6 is a diagram showing the relationship between the remaining time and the remaining amount when hexane, acetone, and a hexane / acetone azeotrope are kept at room temperature (20 ° C.).

FIG. 7 is a perspective view of a conventional cell for infrared spectrometry used for oil measurement.

[Description of Signs] 1 Thermostatic bath 2 Mixed solvent of hexane and acetone 3 Heating device 4 Hexane introduction tube 5 Acetone introduction tube 6,7 Valve 8 Sample processing chamber 9 Solvent vapor piping 10 Valve 11 Heating device 12 Ceramic vessel 13 Heating Device 14 Sample support made of stainless steel 15 Sample 16 Cooling device 17 Nitrogen gas inlet tube 18 Nitrogen gas outlet tube 19, 20 Valve 21 Pressure regulating valve 22 Gas chromatography 23 Control device with microcomputer 31 Potassium bromide powder 32 Spatula 33 Extracted organic matter 41 Heating device with temperature control mechanism 42 Local exhaust device 43 Glass petri dish for sample boiling 45 Mixed solvent of acetone and hexane 46 Sample

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-55-126844 (JP, A) JP-A-61-133298 (JP, A) JP-A-7-233398 (JP, A) Maruzen Co., Ltd. Handbook Basics Revised 3rd Edition " (II) -145 1984 (58) Field surveyed (Int. Cl. ⁷ , DB name) G01N 33/28 G01N 1/00

Claims (10)

(57) [Claims] An oil component is dissolved in a mixed solvent comprising a plurality of types of volatile organic solvents and having a minimum azeotropic point lower than the boiling point of each of the volatile organic solvents, and utilizing a boiling point difference between the mixed solvent and the oil component. Removing the mixed solvent, selectively taking out the oil component and measuring the infrared absorption intensity of the CH bond,
An oil content measurement method for quantifying the oil content based on the value. 2. The method according to claim 1, wherein the mixed solvent is a plurality of volatile organic solvents having different boiling points. 3. The method according to claim 1, wherein the mixed solvent comprises a ketone solvent and an aliphatic hydrocarbon solvent. 4. The method according to claim 1, wherein the mixed solvent is a plurality of volatile organic solvents having different boiling points. 5. The method according to claim 1, wherein the mixed solvent has a minimum azeotropic point.
4. The method for measuring oil content according to 2 or 3. 6. The oil content measuring method according to claim 5, wherein the lowest azeotropic point of the mixed solvent is lower than the boiling point of the oil component to be determined. 7. The method according to claim 1, wherein the mixed solvent comprises hexane and acetone. 8. The method for measuring an oil content according to claim 6, wherein the mixed solvent comprises hexane and acetone, and the composition ratio of the hexane is not less than the composition ratio showing the lowest azeotropic point of the mixed solvent. 9. The method according to claim 6, wherein the mixed solvent comprises hexane and acetone, wherein the composition ratio of the hexane is 44% by weight or less, and the acetone content is 56% by weight or more. 10. The method according to claim 6, wherein the mixed solvent comprises hexane and acetone, wherein the composition ratio of the hexane is 44 to 34% by weight and the amount of acetone is 56 to 66% by weight.