JP2017020924A - Resin discrimination device and resin discrimination method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a resin discrimination device and a resin discrimination method capable of discriminating a kind of a resin contained in a sample from X rays emitted from the sample when the sample has been irradiated with the X rays.SOLUTION: A resin discrimination device includes: an X-ray tube 1 that emits X rays; an X-ray detector 3 that detects the X rays emitted from a sample 2 which has been irradiated with the X rays; a data processing section 10 that creates spectrum based on a detection signal obtained by the X-ray detector 3; a peak extraction section 12 that extracts a spectral line due to Compton scattering originating in a target element of the X-ray tube 1 and a spectral line due to Rayleigh scattering on the spectrum, and determines the peak strength; and a discrimination section 13 that calculates a scattering intensity ratio which is a ratio of the Rayleigh scattering intensity and the Compton scattering intensity, and discriminates a type of a resin contained in the sample 2 from the scattering intensity ratio.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a resin discriminating apparatus and a resin discriminating method for discriminating the type of resin. More specifically, the present invention relates to a method for discriminating the type of resin by irradiating a sample with excited X-rays and using X-rays emitted from the sample accordingly The present invention relates to a resin discrimination device and a resin discrimination method.

  As a quantitative method by fluorescent X-ray analysis, a calibration curve method and a fundamental parameter method (hereinafter referred to as “FP method”) are well known. The calibration curve method is obtained by preparing a calibration curve representing the relationship between the X-ray intensity and the element content (or concentration) in advance from the result of measuring a standard sample, and measuring the target sample in light of this calibration curve. The element content is obtained from the X-ray intensity value. On the other hand, in the FP method, the element content is obtained by theoretical intensity calculation from an X-ray intensity value obtained by measurement on a target sample. Although the FP method is inferior to the calibration curve method in terms of quantification accuracy, there is an advantage that quantification can be easily performed without necessarily requiring a standard sample.

  For example, a method described in Patent Document 1 is known as a method for quantifying a sample containing an element that cannot measure fluorescent X-rays, such as hydrogen and carbon, for example, an organic compound such as a resin, by the FP method. In this method, assuming the principal component element of the resin contained in the sample, the fluorescent X-ray is used for each component other than the main component, while the scattered X-ray is used for the main component, Quantitative values of the main component and other various components are determined by the FP method by comparing with the theoretical strength. Although such quantitative methods can estimate the quantitative values of various components, it is difficult to specify organic compounds because the main component elements are assumed. For example, the type of resin contained in a sample is discriminated. It is not possible. Therefore, the quantitative value obtained by the above method can only be used as information for pretreatment for separating the resin from other substances (for example, metals). This is the actual situation.

JP 2010-223908 A

  The present invention has been made to solve the above problems, and its main purpose is to determine the type of resin contained in the sample from the X-rays emitted from the sample when the sample is irradiated with X-rays. An object of the present invention is to provide a resin discrimination device and a resin discrimination method that can be used.

The resin discriminating apparatus according to the present invention made to solve the above problems is as follows.
a) an X-ray source emitting X-rays;
b) an X-ray detector for detecting X-rays emitted from a sample irradiated with X-rays from the X-ray source;
c) spectrum creation means for creating a spectrum based on the detection signal obtained by the X-ray detector;
d) Scatter for detecting a spectrum line by Compton scattering and a Rayleigh scattering spectrum line derived from the target element of the X-ray source on the spectrum, and calculating a scattering intensity ratio which is a ratio of the Compton scattering intensity to the Rayleigh scattering intensity. Intensity ratio calculating means;
e) A resin type discriminating means for discriminating the type of resin contained in the sample from the scattering intensity ratio.

  In the present invention, when a sample containing a resin is irradiated with X-rays from an X-ray source, the spectrum obtained from the X-rays emitted from the sample is subjected to Rayleigh scattered X-rays and Compton mainly derived from the target element of the X-ray source. Scattered X-rays appear, and the ratio between the Rayleigh scattering intensity and the Compton scattering intensity is found to change depending on the type of resin contained in the sample. Here, the resin is not limited to a solid resin such as plastic, but includes various forms of resin such as liquid and powder. In addition to synthetic resins, natural resins are also included.

In the present invention, comprising a storage unit for storing the scattering intensity ratio determined in advance for a plurality of known resins,
The resin type discrimination means discriminates the type of resin contained in the sample by comparing the scattering intensity ratio calculated by the scattering intensity ratio calculation means with a plurality of scattering intensity ratios stored in the storage unit. Good.
In this case, the scattering intensity ratio of the known resin stored in the storage unit may be a value obtained from the theoretical intensity of Compton scattering and Rayleigh scattering calculated from the contained element and structure of the resin. It may also be a value obtained from the Compton scattering and Rayleigh scattering intensities (measured intensities). In such a configuration, the resin type discriminating means, for example, out of the scattering intensity ratios stored in the storage unit, a resin having a scattering intensity ratio with the smallest difference from the scattering intensity ratio calculated by the scattering intensity ratio calculating means, It is determined that the type of sample included in the sample.

  Further, the resin type discriminating means obtains a relational expression using a plurality of scattering intensity ratios stored in the storage unit as independent variables and a scattering intensity ratio calculated for the sample as a dependent variable by regression analysis. You may make it discriminate | determine the kind of resin contained in a sample from the coefficient of each independent variable in a relational expression. In this case, it can be estimated that the coefficient of each independent variable is the mixing ratio of the resin contained in the sample. Further, all the coefficients of the independent variables in the obtained relational expression may be estimated as the resin mixing ratio, but only a variable larger than a predetermined set minimum value may be used as the resin mixing ratio. Specifically, for example, when the coefficient value is larger than the set minimum value, a known resin corresponding to an independent variable (scattering intensity ratio stored in the storage unit) having the coefficient is included in the sample at the ratio of the coefficient. If the coefficient value is equal to or less than the set minimum value, it is determined that the known resin corresponding to the independent variable having the coefficient is not included in the sample. According to such a configuration, the resin corresponding to the term resulting from the detection error of the X-ray detector among the independent variable terms of the obtained relational expression is erroneously determined as one of the types of resins contained in the sample. Can be avoided.

  Some resins contain elements that emit fluorescent X-rays, such as chlorine (Cl) and sulfur (S), and when such resins are irradiated with X-rays, the X-ray fluorescence spectrum derived from these elements is can get. Therefore, when such a resin is used as a sample, the resin type discriminating means detects fluorescent X-rays emitted from the sample on the spectrum, and the fluorescent X-ray intensity and the scattering intensity ratio calculating means The type of resin contained in the sample may be discriminated from the calculated scattering intensity ratio.

  In the resin discriminating apparatus of the present invention described above, it is preferable to include a discrimination result display unit for displaying the result discriminated by the resin type discriminating means. In particular, in the case of the configuration in which the type of resin is discriminated by the above-described regression analysis, the solution (relational expression) is not necessarily one. Therefore, when multiple solutions (relational expressions) are obtained and multiple different determination results are obtained, these determination results are displayed on a print or display screen, and the results selected by the analyst are displayed on the sample. The resin included may be determined. When a plurality of relational expressions are obtained, for each relational expression, the type of resin contained in the sample is determined from the coefficient of each independent variable in the relational expression, and the scattering intensity ratio obtained from the relational expression The degree of coincidence with the scattering intensity ratio calculated by the scattering intensity ratio calculating means may be obtained. Then, when the resin type and the degree of coincidence included in the sample determined by the resin determining unit for each of a plurality of relational expressions are displayed on a print or display screen, the analyst includes the sample in the sample with reference to the degree of coincidence. The type of resin used can be discriminated.

  Another aspect of the present invention is a resin discrimination method corresponding to the above-described resin discrimination apparatus, which irradiates a sample with X-rays emitted from an X-ray source and analyzes the X-rays emitted from the sample accordingly. Calculating a scattering intensity ratio which is a ratio of Compton scattering intensity and Rayleigh scattering intensity derived from the target element of the X-ray source, and discriminating the type of resin contained in the sample from the scattering intensity ratio. .

  In the resin discrimination method, the type of resin contained in the sample may be discriminated by comparing the scattering intensity ratio calculated for the sample with the scattering intensity ratio obtained in advance for a plurality of known resins. , A relational expression having a scattering intensity ratio obtained in advance for a plurality of known resins as an independent variable and a scattering intensity ratio calculated for the sample as a dependent variable is obtained by regression analysis, and each independent variable in the obtained relational expression is calculated. The type and mixing ratio of the resin contained in the sample may be determined from the coefficient.

  In addition, X-rays emitted from the sample are analyzed in response to irradiation of the sample with X-rays, the intensity of the fluorescent X-rays contained in the sample is calculated, and the intensity of the fluorescent X-rays and the sample are calculated. The type of resin that emits fluorescent X-rays, such as chlorine (Cl) and sulfur (S), other than the resin contained in the sample, may be determined from the scattering intensity ratio calculated for.

  As described above, according to the resin discriminating apparatus and the resin discriminating method of the present invention, the type of resin contained in the sample is discriminated by analyzing the X-rays emitted from the sample when the sample is irradiated with X-rays. can do.

1 is a schematic configuration diagram of an example of an X-ray fluorescence analyzer showing an embodiment of a resin discrimination device according to the present invention. The flowchart of the resin discrimination | determination process in the Example. The figure which shows the result of having measured the fluorescence X-ray spectrum of three types of resin pure substances.

  First, a fluorescent X-ray analysis apparatus that is an example of a resin discrimination apparatus according to the present invention will be described. FIG. 1 is a schematic configuration diagram of an energy dispersive X-ray fluorescence analyzer.

  In FIG. 1, under the control of the control unit 15, when the excited X-ray emitted from the X-ray tube 1 whose target material is rhodium (Rh) hits the sample 2, the fluorescent X-ray excited by the excited X-ray is The sample 2 is emitted from the sample 2 and is incident on an X-ray detector 3 such as a silicon drift detector to be detected as a current signal. A part of the excited X-rays that have hit the sample 2 are scattered by the sample 2, and such scattered X-rays are also detected by the X-ray detector 3. The detected current is integrated inside the X-ray detector 3, and the integration is reset when a certain time is exceeded. Thereby, the output signal of the X-ray detector 3 becomes a step-like current pulse signal. The height of each step of this signal corresponds to the energy of each element contained in the sample 2. This current pulse signal is input to the preamplifier 4 and further to a proportional amplifier 5 including a waveform shaping circuit, and is formed into a pulse having an appropriate shape having a wave height corresponding to the height of each step and output.

  The A / D converter (ADC) 6 samples and digitizes the pulse wave-shaped analog signal at a predetermined sampling period. The multi-channel analyzer (MCA) 7 discriminates each pulse according to the peak value of the digitized pulse signal and then counts it, creates a peak distribution diagram, that is, an X-ray spectrum, and inputs it to the data processing unit 10. Data constituting the X-ray spectrum is stored in the spectrum storage unit 11. As will be described later, in the X-ray spectrum, a spectrum line unique to each element appears as a peak at a position corresponding to the energy value of the fluorescent X-ray emitted from the element contained in the sample to be analyzed. In addition, peaks of Compton scattered X-rays and Rayleigh scattered X-ray spectral lines derived from the target element of the X-ray tube 1 also appear. In the data processing unit 10, the peak extraction unit 12 detects each peak appearing on the X-ray spectrum, and extracts the peak of the target element or compound. The discriminating unit 13 uses the intensity of each extracted peak, that is, the X-ray intensity value, to execute a process for discriminating the type of resin contained in the sample. In the present embodiment, a characteristic resin discrimination process is executed in the discrimination unit 13.

Next, the procedure of the resin discrimination process according to the present embodiment will be described with reference to the flowchart of FIG.
When the sample 2 is set at a predetermined position (step S1) and the start of measurement is instructed by the operation unit 16 (step S2), the sample 2 is irradiated with X-rays and the X-rays emitted from the sample 2 accordingly. Is detected by the X-ray detector 3 (step S3). Subsequently, the data processing unit 10 creates an X-ray spectrum based on the detection signal of the X-ray detector 3 (step S4), and the peak extraction unit 12 causes the peak of the RhKα ray on the X-ray spectrum and the RhKα ray. The peak due to the Rayleigh scattered ray and the peak of the fluorescent X-ray spectrum are extracted and the intensity is obtained (steps S5 and S6). Moreover, the peak extraction part 12 calculates | requires a peak energy with the peak intensity of a fluorescent X-ray spectrum.

  The discriminating unit 13 calculates the ratio between the peak intensity of the RhKα ray due to the Compton scattered ray and the peak intensity of the RhKα ray due to the Rayleigh scattered ray (corresponding to the scattering intensity ratio of the present invention, hereinafter referred to as “C / R ratio”). (Step S7). Then, the calculated C / R ratio is compared with the C / R ratio of the database stored in advance in the storage unit 131 (step S8), and the type of resin contained in the sample 2 is determined (step S9). .

Here, it is assumed that the storage unit 131 stores, for example, a table as shown in Table 1 below. As the C / R ratio of the known resin types shown in Table 1, the C / R ratio obtained in advance using the apparatus according to the present embodiment may be used for a sample (resin pure substance) consisting only of various resins. Further, it may be obtained from theoretical values of Compton scattering intensity and Rayleigh scattering intensity calculated from the composition of various resins. FIG. 3 shows examples of fluorescent X-ray spectra of three kinds of resin pure substances (polyethylene (PE), nylon, polyethylene terephthalate (PET)). In FIG. 3, the fourth peak from the right and the third peak from the right with arrows indicate the Compton scattered ray and Rayleigh scattered ray of the RhKα ray, respectively. The C / R ratio can be obtained from the peak intensity of the Compton scattered ray and the Rayleigh scattered line of each resin.

  For example, the discriminating unit 13 obtains the difference between the C / R ratio calculated in step S7 and each C / R ratio in the table, extracts the resin type having the smallest C / R ratio, and uses it as a sample. It is determined as the type of resin contained in. In addition, it is determined whether the calculated C / R ratio value is included in a predetermined numerical range (for example, a range of ± 0.1) centered on the C / R ratio value shown in Table 1, and the numerical range. If it is contained in the sample, the resin type is determined as the type of resin contained in the sample.

Moreover, when the peak of the fluorescent X-ray spectrum is extracted, the type of resin contained in the sample may be determined from the peak information (peak energy and peak intensity) and the C / R ratio. Since the peak information of the fluorescent X-ray spectrum indicates that an element such as chlorine (Cl) or sulfur (S) is contained in the resin, the type of resin contained in the sample can be more accurately determined.
The type of resin thus obtained is output from the output unit 14 (corresponding to the “discrimination result display unit” of the present invention) as a display or print (step S10).

  By the way, when the sample 2 includes a plurality of types of resins, the C / R ratio of the sample is a total value obtained by multiplying the mixing ratio of each resin by the C / R ratio of the resin pure substance. Therefore, as a result of the determination unit 13 obtaining a difference between the C / R ratio calculated for the sample 2 and the C / R ratio of each resin type in the table, the difference exceeds a predetermined value for any resin type. If any of the resin types is out of the specified numerical range centered on the C / R ratio, it is determined that multiple types of resins are included, and the method described below Thus, the type of resin contained in the sample may be determined.

First, the determination unit 13 arranges the C / R ratios in the table of Table 1 in ascending order of difference from the C / R ratio calculated for the sample, and sets the values of these C / R ratios as independent variables (X1,. X2, X3...), The following relational expression (1) is set with the C / R ratio calculated for the sample as the dependent variable Y.
Y = a.X1 + b.X2 + c.X3 + (1)
Here, a, b, c... Indicate coefficients representing the mixing ratio of each resin (where a + b + c +... = 1). The determination unit 13 determines the value of each coefficient by regression analysis while changing the values of the coefficients a, b, c, and the like. In addition, well-known analysis software such as “Excel” can be used for such regression analysis.

  Then, as a result of the regression analysis, the type of resin contained in the sample 2 is determined based on the coefficient value obtained. For example, the resin types corresponding to the C / R ratios up to the top third are arranged in order from the largest coefficient value, and the resin types included in the sample 2 are estimated as combinations. Further, a resin type corresponding to a C / R ratio having a coefficient value equal to or greater than a predetermined set minimum value may be estimated as a combination of types of resins included in the sample 2.

Furthermore, if multiple relational expressions (solutions) are obtained as a result of regression analysis, the combination of resin types contained in the sample is estimated for all of these relational expressions, and these are used as candidates for the combination of resin types. Also good. And it is good to display the combination of the resin kind used as a candidate by a display screen or printing, and let an analyst select an appropriate combination from these. Also, for all of the plurality of relational expressions, the degree of coincidence between the Y value obtained from each relational expression and the Y (C / R ratio) calculated for the sample is calculated, and the degree of coincidence of each is calculated as a candidate resin type. It may be displayed by a display screen or printing together with the combination. In this case, the display means and the printing means for displaying the display screen correspond to the coincidence degree display unit of the present invention.
According to such a configuration, even when a sample includes a plurality of types of resins, the types of these resins can be determined. If the degree of coincidence is displayed together with a combination of candidate resin types, the analyst can select a combination of resin types with reference to the degree of coincidence.

In the above embodiment, the process of determining the type of resin in the sample 2 from the table stored in the storage unit 131 and the process of determining the type of resin in the sample 2 by regression analysis are used in combination. Only the above process may be used for the determination process of the type of resin in the sample 2.
In addition, the present invention is not limited to the above embodiment, and any type of spectrum may be used as long as a spectrum is created from a detection signal of X-rays emitted from a sample and a ratio between Compton scattering intensity and Rayleigh scattered light intensity can be obtained from the spectrum. An X-ray analyzer may be used, and the target material and the X-ray detector are not limited to those described in the embodiments.

DESCRIPTION OF SYMBOLS 1 ... X-ray tube 2 ... Sample 3 ... X-ray detector 4 ... Preamplifier 5 ... Proportional amplifier 6 ... A / D converter 7 ... Multichannel analyzer (MCA)
DESCRIPTION OF SYMBOLS 10 ... Data processing part 11 ... Spectrum storage part 12 ... Peak extraction part 13 ... Discrimination part 131 ... Storage part 14 ... Output part 15 ... Control part 16 ... Operation part

Claims (10)

a) an X-ray source emitting X-rays;
b) an X-ray detector for detecting X-rays emitted from a sample irradiated with X-rays;
c) spectrum creation means for creating a spectrum based on the detection signal obtained by the X-ray detector;
d) Scatter for detecting a spectrum line by Compton scattering and a Rayleigh scattering spectrum line derived from the target element of the X-ray source on the spectrum and calculating a scattering intensity ratio which is a ratio of the Rayleigh scattering intensity and the Compton scattering intensity. Intensity ratio calculating means;
e) A resin discriminating apparatus comprising: a resin type discriminating unit that discriminates the type of resin contained in the sample from the scattering intensity ratio. In the resin discrimination device according to claim 1,
A resin discrimination device comprising a discrimination result display unit for displaying a result discriminated by the resin type discrimination means. In the resin discrimination device according to claim 1 or 2,
A storage unit for storing a scattering intensity ratio obtained in advance for a plurality of known resins;
The resin type discriminating unit discriminates the type of resin contained in the sample by comparing the scattering intensity ratio calculated by the scattering intensity ratio calculating unit with a plurality of scattering intensity ratios stored in the storage unit. A resin discrimination device characterized by that. In the resin discriminating device according to claim 3,
The resin type discriminating means obtains a relational expression by regression analysis using the plurality of scattering intensity ratios stored in the storage unit as independent variables and the scattering intensity ratio calculated by the scattering intensity ratio calculating means as a dependent variable. A resin discriminating apparatus that discriminates the type and mixing ratio of the resin contained in the sample from the coefficient of each independent variable in the relational expression. In the resin discrimination device according to claim 4,
When a plurality of relational expressions are obtained by regression analysis, the resin type determining means determines the type of resin contained in the sample from the coefficient of each independent variable in each relational expression, and the relation Obtain the degree of coincidence between the scattering intensity ratio obtained from the equation and the scattering intensity ratio calculated by the scattering intensity ratio calculating means,
A resin discriminating apparatus, comprising: a coincidence degree display unit for displaying the type of resin contained in the sample and the degree of coincidence determined by the resin discriminating unit for each of a plurality of relational expressions. In the resin discrimination | determination apparatus in any one of Claims 1-5,
The resin type discriminating means detects fluorescent X-rays emitted from the sample on the spectrum, and the resin contained in the sample from the intensity of the fluorescent X-rays and the scattering intensity ratio calculated by the scattering intensity ratio calculating means. A resin discriminating apparatus characterized by discriminating types.   A ratio of Compton scattering intensity and Rayleigh scattering intensity derived from the target element of the X-ray source by irradiating the sample with X-rays emitted from the X-ray source and analyzing the X-rays emitted from the sample accordingly. A resin discrimination method that calculates a scattering intensity ratio and discriminates the type of resin contained in the sample from the scattering intensity ratio. In the resin discriminating method according to claim 7,
A resin discrimination method characterized in that the type of resin contained in the sample is discriminated by comparing the scattering intensity ratio calculated for the sample with a scattering intensity ratio obtained in advance for a plurality of known resins. In the resin discriminating method according to claim 7,
A relational expression having a scattering intensity ratio determined in advance for a plurality of known resins as an independent variable and a scattering intensity ratio calculated for the sample as a dependent variable is obtained by regression analysis, and the coefficient of each independent variable in the obtained relational expression From the above, a resin discriminating method comprising discriminating the type and mixing ratio of the resin contained in the sample. In the resin discriminating method according to any one of claims 7 to 9,
The X-ray emitted from the sample is analyzed in response to the X-ray being irradiated to the sample, the intensity of the fluorescent X-ray emitted from the sample is calculated, and the intensity of the fluorescent X-ray and the sample are calculated. A resin discrimination method characterized by discriminating the type of resin contained in the sample from the scattered intensity ratio.

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