JPH08114542A - Press oil analyzing method - Google Patents

Abstract

PURPOSE: To accurately determine the content of the press oil in the solvent in a short time by using the light beam at a wavelength within the specified range so as to measure the absorbance of the press oil washing hydro carbon group solvent, and using the analytical curve, which is previously formed on the basis of the maximum value of the absorbance. CONSTITUTION: Absorbance of the press oil washing hydro carbon group solvent is measured by using the light beam at a wavelength in a range at 300-270nm, and the content of the press oil in the washing solvent is analyzed by using the analytical curve, which is previously formed on the basis of the maximum value of the absorbance. The light beam at a wavelength in the range at 300-270nm exists in the ultraviolet rays area, and an absorbance meter is used for analysis thereof. Absorbance is measured, changing the incident wave length, in the range at 300-270nm, and when the peak position is detected, a little displacement of the wavelength absorbed by the sample can be corrected. Absorbance of the wavelength at 300-270nm of plural solvent, in which a known quantity of the press oil is added, is measured, and the analytical curve is formed by plotting the maximum absorbance and the addition quantity of the press oil, and this analytical curve is used for determining the press oil in the washing solvent.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydrocarbon type cleaning agent for washing and removing the pressing oil on a product manufactured by press molding or the like, and particularly to an analysis for measuring the amount of the pressing oil mixed in the cleaning agent. Regarding the method.

[0002]

2. Description of the Related Art In the manufacturing process of metal parts, press oil often adheres to the product. Especially in the press molding process, press oil is generally used for pressing, so that not only the mold but also the product. Also press oil adheres.

When the press oil adheres to the product, the product is washed to remove the press oil.

The cleaning agent used to remove the press oil has hitherto been known as CFC11 for reasons such as nonflammability, oil solubility, drying property and good crevice cleaning property, and steam cleaning capability.
3 and chlorine-based organic solvents such as trichloroethane and trichlorethylene have been widely used. However, CFC (Chlo
ro Fluoro Carbon) has been pointed out to have an ozone depleting effect,
Its use is severely restricted, 1 for CFC113
The policy of total abolition was announced in December 995. In addition, some chlorine-based organic solvents have an ozone depleting effect and are also suspected to be carcinogenic. Therefore, there is an increasing tendency to restrict their use and abolish them. Therefore, it has become essential to select a new cleaning agent that replaces the conventional CFC and chlorine-based organic solvent.

There are many kinds of alternative cleaning agents, and the optimum cleaning agent varies depending on the product form and the required cleaning condition. However, a hydrocarbon solvent is used for cleaning integrated circuits (ICs) and lead frames for transistors. Is increasing. Since hydrocarbon solvents are flammable, it is a rule to carry out immersion cleaning. Therefore, the press oil washed off by the washing dissolves in the hydrocarbon solvent. Therefore, since the solvent is gradually contaminated with the press oil, if the amount brought in is large, the cleaning may be incomplete or the press oil may be redeposited. Therefore, it is necessary to control the amount of press oil by measuring the amount of press oil brought into the cleaning solvent and to control the quality of the cleaning solvent. Further, in order to regenerate the hydrocarbon solvent, a method of regenerating the solvent by a distillation method or the like is generally used by utilizing the difference in boiling point between the solvent and the press oil. From the viewpoint of grasping the amount level, it is necessary to establish an analytical method for analyzing the amount of press oil contained in the hydrocarbon solvent.

As an analytical method for analyzing the amount of the press oil contained in the hydrocarbon solvent, an infrared spectroscopic analysis method, a gas chromatography method, a liquid chromatography method and the like can be considered.

Therefore, the possibility of analyzing by the above method was examined by preparing a hydrocarbon solvent containing a certain amount of press oil in advance. As a result, it was found that the infrared spectroscopic method could not be analyzed because no specific absorption peak due to the inclusion of the press oil was observed. In addition, as a result of trying the analysis method by the gas chromatography method and the liquid matography method, it was possible to analyze by increasing the sensitivity of the detector and the recorder, but the noise was large and the resolution was poor. It was confirmed that it takes a considerably long time to quantify because the time required for each analysis is long. For example, quantification by gas chromatography requires 3-4 hours.

[0008]

An object of the present invention is to solve the above-mentioned drawbacks of the prior art and to provide a method for accurately and simply quantifying the content of press oil contained in a hydrocarbon solvent in a short time. To provide.

[0009]

The above object can be achieved by providing a method for analyzing press oil according to the present invention. That is, (1) a hydrocarbon-based solvent for cleaning press oil is added to 300
The absorbance is measured using a light ray having a wavelength in the range of nm to 270 nm, and the content of the press oil in the cleaning solvent is analyzed from the maximum value of the absorbance using a calibration curve previously measured. It is achieved by a press oil analysis method.

A UV-visible absorptiometer is used for analysis because light rays having a wavelength in the range of 300 nm to 270 nm, for example, a wavelength of 290 nm are in the ultraviolet (UV) region.

When the absorbance is measured in the range of 300 to 270 nm while changing the incident wavelength and the peak position is detected, a slight shift in the absorption wavelength due to the sample can be corrected.

A plurality of hydrocarbon solvents to which a known amount of press oil has been added are prepared in advance, and the solvent of 300 nm to 2 nm is used.
The absorbance of light having a wavelength in the range of 70 nm is measured, and the maximum absorbance of these solvents and the amount of press oil added are plotted to create a calibration curve. Next, the maximum value of the absorbance of light having a wavelength in the range of 300 nm to 270 nm was measured for the hydrocarbon solvent for press oil washing used for washing the product, and the amount of press oil in the washing solvent was measured using a calibration curve. Quantify. Such a quantitative method is called an absorptiometric method.

Here, what is measured by the absorptiometer is the light transmittance (%), and the light transmittance at each wavelength and 100%
Absorbance (%) is calculated from the difference in transmittance and used as the absorbance.

The upper limit of analysis of the amount of press oil in the hydrocarbon solvent for cleaning by the absorptiometry is about 1000 microliter / liter (μl / l). Therefore, it is desirable to appropriately dilute a sample having a concentration exceeding the upper limit value by using the same clean hydrocarbon solvent for cleaning.

The lower limit value of the press oil amount analysis is about 1
It is 0 μl / l.

[0016]

EXAMPLES Examples of the present invention will be described. However,
The description is an understanding of the invention and is not intended to limit the invention.

Aqua Solvent GX manufactured by Aqua Chemical Co., Ltd. was prepared as a hydrocarbon solvent for cleaning, and G6050 manufactured by Nippon Machine Oil Co., Ltd. was prepared as a press oil. Next, G6050 is added to Aqua Solvent GX in an amount of 10 to 1000 μl /
A sample added in the concentration range of 1 was prepared.

As a UV-visible absorption spectrophotometer, a U-3210 type self-recording spectrophotometer manufactured by Hitachi, Ltd. was used.

Next, a clean cleaning hydrocarbon solvent containing no press oil was placed in a reference cell (10 mm width) of the spectrophotometer, and the solvent containing a known amount of press oil was placed in a sample cell. Next, operate the spectrophotometer to scan at a wavelength of 600 nm to 200 nm and a scanning speed of 120 nm.
The wavelength was scanned at / min.

In FIG. 1, the amount of press oil added is 500 μl / l.
An example of the maximum absorbance (absorption peak) detected at the time of is shown.

It was shown that there was a large absorption peak near the wavelength of 290 nm, more precisely at 288 nm.
Therefore, several kinds of samples were prepared by adding a known amount of press oil, and the heights of the absorption peaks (maximum absorbance) detected for these samples were measured, and the amount of press oil added and the corresponding maximum absorbance near 290 nm were measured. Was plotted to create a calibration curve. FIG. 2 shows an example thereof.

As is clear from FIG. 2, the press oil amount and the height of the absorption peak (maximum absorbance) are in a substantially proportional relationship. Moreover, the maximum absorbance shows a large change with respect to the change in the amount of press oil, and it can be seen that the sensitivity of the press oil analysis method of the present invention is good. Furthermore, the analysis was repeated 3 times on the same sample, and it was confirmed that the difference in maximum absorbance was within 1%.

[0023]

According to the press oil analysis method of the present invention, the time required to measure the height of one absorption peak is within 2 minutes. Therefore, the time required from the preparation of the calibration curve to the completion of the quantitative analysis of the unknown sample is about 20 minutes. This required time is significantly shorter than the time required for the analysis by the gas chromatography method or the liquid chromatography method.

Further, since the method for analyzing press oil of the present invention has high detection sensitivity, it is remarkably excellent in accuracy of analysis value and reproducibility of repeated measurement. Further, since there is no need for pretreatment of the test liquid, there are advantages that it is simple and does not require skill in measurement.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of peaks of detected absorption when a press oil addition amount is 500 μl / l.

FIG. 2 is a graph showing an example of a calibration curve in which the maximum absorbance and the amount of press oil added are plotted.

Claims (1)

[Claims] 1. A hydrocarbon-based solvent for cleaning press oil is 300 nm.
The absorbance is measured using a light ray having a wavelength in the range of ˜270 nm, and the content of the press oil in the cleaning solvent is analyzed from the maximum value of the absorbance using a calibration curve previously measured. Press oil analysis method.