JP4679486B2 - Surface organic compound concentration measurement method - Google Patents

Description

  The present invention relates to a surface organic compound concentration measurement method for measuring the concentration of a surface organic compound such as lubricating oil applied to the surface of a welding wire or the like.

  Usually, when manufacturing a welding wire or the like, oil is applied immediately before the wire is stored in a packaging container such as a spool or a pail pack. In this coating process, it is extremely important to manage the amount of oil adhesion within a specific range. When the amount of oil is insufficient, rust occurs or the wire is fed at a constant speed during welding. On the contrary, when the amount of oil is excessive, combustion gas of oil is mixed in the weld metal, resulting in pore defects and reducing the strength of the weld. For this reason, it is necessary to measure the oil amount immediately after application, and when the oil amount is not within a predetermined range, it is necessary to promptly feed back to the operating conditions of the coating apparatus and correct the conditions.

  Based on such a request, conventionally, means for measuring the oil amount on the wire surface has been proposed (Patent Documents 1 and 2). As this oil amount measuring method, (a) a method using an oil concentration meter using carbon tetrachloride as an extraction solvent, (b) a method using an oil concentration meter using an alternative fluorocarbon as an extraction solvent, (c) KBr, etc. Making a tablet with a substance that does not absorb infrared rays, and using an infrared spectrophotometer (FTIR) using direct reflected light from the tablet surface, (d) Directly reflecting infrared rays on the surface of the object to be measured and reflecting directly There are infrared spectroscopy for detecting light, and (e) a method of wiping the wire surface with filter paper or the like, and estimating the oil adhesion amount from the state of stain adhesion on the filter paper surface.

JP 2005-257553 A JP 2005-91306 A

  However, the conventional method for measuring the oil amount on the wire surface has the following problems. First, carbon tetrachloride used in the method (a) is a regulated substance of the Montreal Protocol, and is a substance that can only be used for essential uses such as analysis and measurement, but it will also be abolished at the end of 2007 Will no longer be available. Further, it is an apparatus for measuring oil having C—H bonds, and can measure only the absorbance of infrared rays having a wavelength corresponding to the inter-atomic distance of C—H bonds in the vicinity of 3.4 μm. It is impossible to measure the adhesion amount of a lubricant having only a C—F bond such as PTFE (polytetra-fluoroethylene).

  In the method (b), the solvent used for the extraction is expensive, and most of the alternative chlorofluorocarbon solvents having a C—Cl bond are ozone-depleting substances, and thus are likely to become regulated substances in the future. In this method, as in the method (a), it is impossible to measure lubricating oil other than C—H oil.

  In the method (c), after extracting oil with an organic solvent such as petroleum ether or acetone, mixing with KBr powder, removing the solvent, forming into a tablet, and the amount of oil from the infrared absorbance irradiated to the KBr tablet Measure. While there is an advantage that the solvent is not limited to carbon tetrachloride, it requires a long time for the pretreatment such as evaporation and removal of the solvent and preparation of KBr tablets, so that quick feedback to the operating conditions is difficult.

  The method (d) is used for a coating film meter of a steel sheet and is a simple method, but is a technique for a plate material, and the shape and roughness of an object to be measured are limited. It cannot be used for wires.

  Although the method (e) is very simple, it is unsuitable for oil quantity management of a welding wire for high-strength steel having high quantitative cracking and high hydrogen cracking sensitivity.

  In so-called infrared spectroscopic analysis, transmitted light is used as in the methods (a), (b), and (c) described above, and directly reflected light is used as in the method (d). In addition to the above, there is a method using diffuse reflected light. This method using diffuse reflected light is a method used for structural analysis of a powder sample, and the surface adhering material of the object to be measured has a curvature. There was no application for concentration measurements.

  The present invention has been made in view of such a problem. Regardless of the steel type and oil type of the object to be measured, the amount of oil applied on the object to be measured can be controlled by a highly regulated substance. An object of the present invention is to provide a method for measuring the concentration of a surface organic compound that can be easily measured with high accuracy without using any of the above.

  The surface organic compound concentration measuring method according to the present invention is a method for measuring the organic compound concentration on the surface of a welding wire as an object to be measured, wherein the diameter of the infrared irradiation region is A, the outer diameter of the columnar or cylindrical object to be measured. D, and when the mounting width when a plurality of objects to be measured are arranged in parallel in the infrared irradiation area is B, in the infrared irradiation area so as to satisfy the relationship of A / D ≧ 2, B ≧ (A + D), Columnar or cylindrical objects to be measured are arranged, irradiated with infrared rays, and the absorbance of infrared rays having a specific wavelength is measured using diffusely reflected light from the objects to be measured.

In this surface organic compound concentration measurement method, the organic compounds to be measured include, for example, fatty acid glycerides such as rapeseed oil, fatty acid esters of monohydric alcohols such as rice wax, aliphatic alcohols such as oleic alcohol, erucic acid amide, etc. Fatty acid amides, mineral oils without polar groups, spindle oils without double bonds or polybudenes with double bonds, or perfluoropolyethers without C—H bonds.

  Alternatively, the organic compound to be measured is, for example, PTFE (polytetra-fluoroethylene) attached to the surface of the object to be measured with a binder. Concerning the adhesion amount of these solids, the concentration can be measured with high accuracy by creating a calibration curve for each adhered substance.

  Moreover, the surface organic compound concentration measuring method of the present invention irradiates the object to be measured with infrared rays from two directions, the absorbance is measured, and the average value of the organic compound concentration on the surface of the object to be measured is measured. Can be measured.

  Hereinafter, embodiments of the present invention will be described. As described above, an infrared spectroscopic analyzer using diffuse reflected light is an apparatus that has been conventionally used for structural analysis of powder samples. In the infrared irradiation region, powder particles having a particle size of several μm to 200 μm are present. It is customary that measurements are made with no gaps. For this reason, when the object to be measured is a welding wire as in the present invention, an infrared spectroscopic analyzer using diffuse reflected light cannot be applied as it is.

  However, the present inventors have conducted intensive research and have made a cylindrical or cylindrical shape such as a welding wire having a very large diameter compared to the particle size of a powder sample (a commonly used diameter is 0.8 to 2.4 mm). As a result of experimental research on the method of applying the diffuse reflection type infrared spectroscopic apparatus to the measured object, a plurality of measured objects are arranged so that the width is wider than the infrared irradiation area, as shown in FIG. It has been found that the deposit concentration can be measured accurately by appropriately selecting the infrared irradiation diameter according to the diameter of the object to be measured.

  This is because when a plurality of cylindrical objects (wires) are arranged in parallel on a plane, the light rays irradiated on the sample surface cause diffuse reflection while interfering with adjacent wires. This is considered to be because the reflected light is returned like a plane having a specific surface roughness.

  When the width of the objects to be measured (mounting width) is narrower than the infrared irradiation width, the reflected light from the portion where the sample is not arranged becomes an error, and sufficient measurement accuracy cannot be obtained. For this reason, the mounting width needs to be equal to or greater than (irradiation width 10 outer diameter of object to be measured).

  In addition, when the outer diameter of the object to be measured is larger than the irradiation diameter, the error in infrared absorbance increases depending on whether the arrangement of the measurement objects is axisymmetric with respect to the irradiation castle or not. . Therefore, it is necessary to select an appropriate infrared irradiation diameter according to the wire diameter of the object to be measured.

The present invention has been made based on such knowledge, and as shown in FIG. 1, the diameter A of the infrared irradiation region and the outer diameter D of a columnar or cylindrical object to be measured (welding wire) Between the mounting width B when a plurality of objects to be measured are arranged in the infrared irradiation region,
A / D ≧ 2 (1)
B ≧ (A + D) (2)
In order to satisfy the above relationship, columnar or cylindrical objects to be measured are arranged in the infrared irradiation area, infrared rays are irradiated, and diffused reflected light from the objects to be measured is used to obtain the absorbance of infrared rays of a specific wavelength. measure.

  Thereby, the organic compound concentration on the surface of the object to be measured can be measured. Therefore, according to the present invention, regardless of the steel type and oil type of the object to be measured, the amount of oil applied to the object to be measured can be measured with high accuracy without using a regulated substance with a high environmental load. .

  FIG. 2 is a schematic diagram showing an optical system of a diffuse light reflection type infrared spectrophotometer used in the embodiment of the present invention. Infrared light from the light source is converged by the interferometer 1 and enters the concave mirror M3 through the plane mirrors M1 and M2, and is focused by the concave mirror M3 to irradiate the surface of the sample 2. The diffusely reflected light reflected from the surface of the sample 2 is converged by the concave mirror M4 and then guided to the detector 3 (see FIG. 1) via the plane mirrors M5 and M6.

  For example, two samples (measurement object 2) and a standard sample 2a are fixed on a holder 4 shown in FIG. That is, the standard sample 2a to which no oil is attached and the object 2 to be measured are attached to the holder 4, for example, as shown in FIG. 4, the standard sample 2a → the first object 2 to be measured → the second object to be measured. In the order of 2, the absorbance is measured with an infrared spectrophotometer. Next, the holder 4 is taken out from the measuring apparatus, and as shown in FIG. 5, the holder 4 is turned over and the back side surface is measured in the order of standard sample → measurement object 1 → measurement object 2. Finally, the average value of the measured values (in this case, the average value of four times) can be calculated to obtain the surface oil amount of the DUT 2.

  FIG. 1 is an enlarged view of the vicinity of the sample chamber in FIG. 2, and the mounting width when a plurality of columnar or cylindrical objects 2 having an outer diameter D are arranged in the infrared irradiation region is B. And the diameter of the infrared irradiation area is A.

  In the present invention, A / D ≧ 2 is satisfied. When the value of A / D is less than 2, depending on where in the infrared irradiation area the top of the wire is located, that is, when the sample is mounted so as to be axially symmetric with respect to the infrared irradiation area, The absorbance value changes greatly depending on the deviation. For this reason, the variation of measured values becomes large, and high-precision absorbance measurement cannot be performed.

  In the present invention, B ≧ (A + D) is satisfied. When the width (mounting width) B for arranging the objects to be measured is narrower than the infrared irradiation width, the reflected light from the part where the sample is not arranged becomes an error, and sufficient measurement accuracy cannot be obtained. Also, unnecessarily widening the mounting width leads to an increase in measurement time. Further, when (A + D)> B ≧ A, the absorbance slightly increases as the mounting width increases, resulting in an error in measurement accuracy.

  When the samples are arranged more than (A + D) (B ≧ (A + D)), the reflected light is also returned at the outer edge of the irradiation area, like a plane having a specific surface roughness, similar to the central area of the irradiation area. Even if the mounting width is increased, the absorbance does not fluctuate. For this reason, it is necessary to satisfy B ≧ (A + D).

  The organic compound to be measured in the present invention is, for example, fatty acid glyceride, fatty acid ester of monohydric alcohol, aliphatic alcohol, or perfluoropolyether. These substances are effective substances as a feed lubricant, and need to be controlled to an appropriate amount of adhesion using the method of the present invention.

  Further, the organic compound to be measured can be PTFE (polytetra-fluoroethylene) attached to the surface of the object to be measured by a binder. This PTFE is also an effective substance as a feed lubricant.

  When measuring the organic compound concentration on the surface of the welding wire, the welding wire is irradiated with infrared rays from two directions, the absorbance is measured, and from the average value, the organic compound concentration on the surface of the object to be measured is determined. It is preferable to measure.

  The amount of organic compound (oil) deposited on the wire surface varies in the circumferential direction of the wire depending on the method of applying the oil. FIG. 10 (a) is a diagram schematically showing the state of application oil in a cross section perpendicular to the longitudinal direction of the wire when oil is applied by the dipping method, and FIG. 10 (b) is a case where the oil is electrostatically applied. It is a figure which shows typically the hot water adhesion state. When oil is applied by the dipping method, the fluctuation in the amount of adhesion in the circumferential direction of the wire is small, and when it is applied electrostatically, the fluctuation in the amount of adhesion in the circumferential direction of the wire is large.

  When the amount of oil on the surface of the wire is measured by the FTIR method, only the organic matter adhering to the portion reflecting the infrared rays in FIG. 11 (the upper half in the wire circumferential direction) is measured. For this reason, if the oil adhesion amount on the surface of the wire to which oil is electrostatically applied is measured only from one direction (from only above), the oil amount of the entire wire can be accurately determined due to the influence of the fluctuation of the adhesion amount in the circumferential direction of the wire It may not be possible to measure.

  For this reason, it is preferable to reduce the influence of the variation in the adhesion amount in the circumferential direction of the wire by measuring the oil adhesion amount from multiple directions and averaging the wires arranged in parallel. Thereby, the oil adhesion amount of the whole wire can be evaluated accurately. In this case, the error is considered to decrease as the measurement direction is increased, but on the other hand, the time and labor required for measurement are increased. As shown in FIG. 12, the inventors of the present application measure the oil amount from two directions by installing a plurality of wires in a holder and measuring from the front surface, inverting the front and back and measuring from the back surface again. Then, when this was averaged, it was found that, for example, it was possible to obtain the same measurement accuracy as when the oil quantity was measured and averaged from four directions by changing the measurement direction by 90 °. Then, as shown in FIG. 12, the process of measuring the oil amount twice by turning it upside down is much less labor than the process of measuring the oil amount by changing the direction by 90 °.

  Next, the effects of the present invention will be described with respect to examples that fall within the scope of the present invention compared to comparative examples that depart from the scope of the present invention. FIG. 6 shows the measurement of the sample mounting width and the infrared absorbance using a diffused infrared spectrophotometer with an infrared irradiation diameter of 4.0 mm on a welding wire (wire diameter: 1.2 mm) coated with rapeseed oil. It is a graph which shows the result of having investigated the relationship. Absorbance shows a constant value in the range where the mounting width is A + D or more (5.2 mm or more). If the mounting width is in this area, calculate the correct oil amount based on the calibration curve obtained in advance. Can do. In the region where the mounting width is less than A + D, the absorbance changes as the mounting width increases, and it is difficult to obtain an accurate oil amount.

  The method for creating this calibration curve is as follows. First, the wire which apply | coated the fatty acid glyceride using the immersion method was created, and it was set as the sample. By changing the oil concentration in the immersion tank, the amount of oil attached to the wire was changed. The wire was collected in a glass bottle, the mass was measured, and the oil was extracted with an organic solvent, and then mixed with KBr powder, and the solvent was removed by evaporation to prepare a KBr tablet. The FTIR spectrum was measured by the transmission method, and the oil amount was measured.

Next, the wires were placed on a sample stage and irradiated with infrared rays, and the infrared absorption spectrum was measured from the reflected light, and the area of the —CH ₂ absorption peak was determined. This wire sampling was repeated and, as shown in FIG. 7, measurements were taken from four directions, and the average value of peak areas was obtained. FIG. 8 shows an example of the absorption spectrum of this oil. FIG. 9 shows an example of a calibration curve of the fatty acid glyceride-coated wire obtained as described above. In the calibration curve shown in FIG. 9, the horizontal axis represents the oil amount obtained by the transmission method (oil amount per 10 kg of wire (g)), the vertical axis represents the area of the —CH ₂ absorption peak, and the relationship between the two is shown. It is shown. As shown in FIG. 9, there is a linear function relationship between the peak area y and the oil amount x.

  Table 1 below shows the results of investigating the amount of adhesion by changing the irradiation area, wire size, and coating oil type. In the case of Examples 1 to 21 of the present invention, the amount of oil determined by the diffuse reflection FTIR method is in good agreement with the measured value of the infrared spectroscopy using the KBr tablet, and all are measured correctly.

  On the other hand, in Comparative Examples 1 to 6, since the mounting width B is narrow (B <(A + D), the oil amount obtained by the diffuse reflection FTIR method causes a deviation from the measured value of the infrared spectroscopy using the KBr tablet. It is inappropriate.

  In Comparative Examples 7 to 9, since the number of objects to be measured occupying the irradiated area is small (A / D <2), the diffuse reflection is not sufficiently performed. Therefore, the oil amount obtained by the diffuse reflection FTIR method is Compared to the amount of adhered oil determined by FTIR using KBr, the amount of oil is extremely small, and measurement is not possible correctly.

It is a schematic diagram explaining the structure of this invention. It is a schematic diagram which shows the light absorbency measuring method of embodiment of this invention. Similarly, it is a figure which shows the to-be-measured object and standard sample which were attached to the holder. It is a figure which shows the measurement of the front side of a holder. It is a figure which shows the measurement of the back side of a holder. It is a graph which shows the relationship between the mounting width B and a light absorbency. It is a figure which shows the measurement from 4 directions. It is a figure which shows an example of the absorption spectrum of oil. It is a figure which shows an example of the calibration curve of a fatty-acid-glyceride application | coating wire. It is a figure which shows typically the presence state of coating oil. It is a figure which shows the case where the amount of oil adhesion is measured only from one direction. It is a figure which shows the case where an oil adhesion amount is measured from front and back 2 directions.

Explanation of symbols

1: Interferometer 2: Object to be measured 2a: Standard sample 3: Detector 4: Holder

Claims (4)

In the method of measuring the organic compound concentration on the surface of the welding wire as the object to be measured, the diameter of the infrared irradiation area is A, the outer diameter of the cylindrical or cylindrical object to be measured is D, and the object to be measured is parallel to the infrared irradiation area. When the mounting width in the case of arranging two or more is set to B, columnar or cylindrical objects to be measured are arranged in the infrared irradiation region so as to satisfy the relationship of A / D ≧ 2 and B ≧ (A + D). And measuring the absorbance of infrared light having a specific wavelength using diffusely reflected light from the object to be measured. 2. The surface organic compound concentration measuring method according to claim 1, wherein the organic compound to be measured is a fatty acid glyceride, a fatty acid ester of a monohydric alcohol, an aliphatic alcohol, or a perfluoropolyether. 2. The surface organic compound concentration measuring method according to claim 1, wherein the organic compound to be measured is PTFE (polytetra-fluoroethylene) attached to the surface of the object to be measured by a binder. The infrared rays are irradiated to the object to be measured from two directions, the absorbance is measured, and the concentration of the organic compound on the surface of the object to be measured is measured from the average value. The surface organic compound density | concentration measuring method of any one of these.

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