JP5211359B2 - Sorting device and sorting method for brominated flame retardant-containing resin - Google Patents

Description

  The present invention relates to a sorting apparatus and a sorting method for sorting a resin containing a brominated flame retardant in resin recycling.

  A flame retardant resin containing a flame retardant is used for some of the resins such as plastics used in home appliances. The flame retardant content is usually 1 to 30% by mass of the entire resin, and brominated flame retardants are mainly used as the flame retardant.

  In order to comply with the Home Appliance Recycling Law for such flame retardant resins, it is necessary to have recycling technology for resins such as waste plastics, and to ensure and manage the performance of recycled resins (recycled resins). In order to achieve this, separation technology between a flame retardant-containing resin and a non-containing resin has become an important technology. In addition, while promoting the effective use of recycled resin for home appliances, the use of brominated flame retardants in hazardous substance regulations represented by the European Union's RoHS Directive (directive on restrictions on the use of specific hazardous substances contained in electrical and electronic equipment) In order to comply with the content regulation, it is necessary to prevent the brominated flame retardant from remaining in the recycling of the resin such as waste plastic and mixing the remaining brominated flame retardant into the recycled resin.

As a separation device for plastics and other resins and metals, in general, separation objects are transported by means of transportation such as a conveyor, and the separation objects are irradiated with X-rays and separated using the difference in X-ray absorption rate. There is a separation device having a separation method for identifying the presence or absence of a target component and discharging it to different compartment storage boxes (for example, Patent Document 1). In such a separation apparatus using X-rays, the heavier element to be separated has a higher X-ray absorption rate, and the higher the content of the separation target component, the higher the X-ray absorption rate. Identifies the presence or absence of the target component.
JP-A-5-131176

  Since the bromine-based flame retardant-containing resin contains bromine derived from a bromine-based flame retardant, the resin does not contain a brominated flame retardant, that is, has a higher X-ray absorption rate than a carbon-based resin, When the thickness of these resins is uniform, the presence or absence of brominated flame retardants can be identified and separated by the measured X-ray absorption value.

  The separation object of Patent Document 1 is not a crushed plastic piece but a flattened plastic container, and the presence or absence of chlorine is determined where X-ray absorption is lowest. When the concentration of the component to be separated is high, such as the chlorine concentration in the vinyl chloride resin, the absorption rate of X-rays is high, and the influence of the thickness of the separation object is reduced by flattening, so that the presence or absence of chlorine is correctly determined. Is possible.

  However, when the separation object is a resin piece such as crushed plastic, the size and thickness are not constant. Therefore, for example, when the content of brominated flame retardant is less than 10% (mass ratio) of the entire resin piece, the X-ray absorption is caused by bromine or carbon in the resin when the thickness of the resin piece is different. It is difficult to determine whether something is wrong.

  The present invention has been made in order to solve the above-described problems, and it does not depend on the thickness of a resin piece such as a plastic that is a separation target, but selects a brominated flame retardant having high sorting accuracy. An object is to provide an apparatus and a sorting method.

  A brominated flame retardant-containing resin sorting device according to the present invention for solving the above-mentioned problems is an X-ray source that generates X-rays, an X-ray detector that detects transmitted X-rays that have passed through a separation object, and The sorting apparatus further includes a displacement measuring instrument, the displacement measuring instrument measures the thickness of the separation object, and obtains the measured thickness data of the separation object. The X-ray detector detects the transmitted X-ray transmitted through the separation object, sends the detected transmitted X-ray intensity data to the data processing section, and the data processing section transmits the transmitted X-ray intensity. The correction data based on the data and the data on the thickness of the separation target is sent to the separation unit, and the separation unit selects the brominated flame retardant-containing resin from the separation target based on the correction data.

  In the sorting apparatus of the present invention, in the data processing unit, transmission X-ray intensity data obtained by correcting transmission X-ray intensity data based on thickness data of a separation target is sent as correction data to the separation unit. Take.

  In addition, the data processing unit includes data of a previously measured thickness and transmitted X-ray intensity threshold value, and compares the transmitted X-ray intensity data with the measured intensity threshold value of the separation object as correction data. The data is sent to the separation unit.

  The method for selecting a brominated flame retardant-containing resin according to the present invention for solving the above problems includes a first step of measuring the thickness of a separation target, and a second step of detecting transmitted X-rays of the separation target. A third step of selecting the separation object, and the third step is based on correction data obtained by correcting the intensity of the transmitted X-ray detected in the second step based on the thickness of the separation object measured in the first step. A brominated flame retardant-containing resin is selected from separation objects.

  In the third step, the transmission X-ray intensity data obtained by correcting the transmission X-ray intensity data based on the thickness data of the separation object is sent as correction data to the separation unit, or the correction data is measured in advance. An example is an embodiment in which data comparing the thickness and transmitted X-ray intensity threshold data, transmitted X-ray intensity data, and the measured intensity threshold of the separation object is sent to the separation unit.

  According to the present invention, the influence of the thickness of the separation object among the X-ray absorption of the separation object can be removed, and even the separation objects having different thicknesses can be selected with high accuracy by the separation object component. Is possible. This improves the recovery rate of the brominated flame retardant-free resin used for the recycled material.

  Hereinafter, the present invention will be described in more detail. In the following description of the embodiments, the description is made with reference to the drawings. In the drawings of the present application, the same reference numerals denote the same or corresponding parts.

(Embodiment 1)
FIG. 1 is a side view showing a typical example of the configuration of an X-ray absorption detector of a sorting apparatus for a brominated flame retardant-containing resin according to the present invention.

  In FIG. 1, X-rays generated from an X-ray source 1 are resin pieces 4 (bromine-containing resin pieces 4 a, bromine-free resin pieces) that are separation objects held on a conveyor 3 and transported to an X-ray irradiation region 2. 4b), and the transmitted X-ray P is detected by the X-ray detector 5. In the present invention, the bromine-free resin piece refers to a resin piece containing bromine having a concentration lower than a desired concentration.

  In the X-ray detection apparatus of FIG. 1, the X-ray detector 5 can measure the X intensity distribution in a line or in a plane, for example, an X-ray line sensor, an X-ray imaging intensifier, or an X-ray CCD camera. An X-ray detector 5 such as an X-ray scintillator or a position sensitive proportional counter is used. When these X-ray detectors are used, the position of the bromine-containing resin piece 4a can be specified because the location of the bromine-containing resin piece 4a becomes weak in transmitted X-ray absorption intensity. Further, when these X-ray detectors are used, it is possible to visualize the X intensity distribution in the line or in the plane as a visible image. In the visualized image, the bromine-containing resin piece 4a is displayed with lower brightness than the bromine-free resin piece 4b. In particular, the thicker the resin piece 4 is, the more X-rays are absorbed and the lower the luminance is displayed. By providing the X-ray detector 5 in this way, the difference in X-ray absorption by the resin piece 4 can be converted into data.

  FIG. 2 is a schematic diagram of a sorting apparatus for a brominated flame retardant-containing resin according to the present invention. In the sorting apparatus shown in FIG. 2, first, the resin pieces 4 are supplied onto the conveyor 3 from the sorted resin piece feeder 6. It is assumed that the resin piece 4 which is a separation object conveyed by the conveyor 3 moves from the left side to the right side in FIG. The thickness of the resin piece 4 supplied and transported on the conveyor 3 is measured by the displacement measuring instrument 7, and the measured thickness data is sent to the data processing unit 8. Further, the resin piece 4 is conveyed to the X-ray irradiation region 2 by the conveyor 3, and the intensity of the transmitted X-ray is detected by the X-ray detector 5 as described above, and the detected intensity data of the transmitted X-ray is the data processing unit 8. Sent to. The data processing unit 8 corrects transmitted X-ray intensity data using the thickness data sent from the displacement meter 7 as described later. Data on whether the corrected transmitted X-ray intensity data is below an arbitrary threshold value or exceeds the threshold value is sent to the separation unit 9. The resin piece 4 below the threshold is determined as a bromine-containing resin piece, and is separated so as to be stored in the bromine-based flame retardant-containing resin piece storage box 10 in the separation unit 9. Further, the resin piece 4 whose corrected transmitted X-ray intensity data exceeds the threshold value is determined to be a bromine-free resin piece, and is separated in the separation unit 9 so as to be stored in the brominated flame retardant-free resin piece storage box 11. Is done.

  Fig.3 (a) is a side view of the measurement part of the thickness of the resin piece 4 which is a separation object which concerns on this invention. As shown in FIG. 3 (a), in the measurement unit, the thickness of the resin piece 4 (sorted resin piece) held and conveyed on the conveyor 3 is measured with a laser 12 or the like by the displacement measuring instrument 7, Data is sent to the data processing unit 8 (omitted in FIG. 3A).

  As the displacement meter 7, a laser displacement meter sensor, an ultrasonic displacement sensor, a PSD (Position Sensitive Device) displacement sensor, an optical fiber sensor, a photoelectric sensor, or the like can be used. A light emitting diode is used as a light source element used in the photoelectric sensor, and a photodiode, a phototransistor, a photo IC, or the like is used as a light receiving element. If the correct amount of reflection cannot be obtained due to the color and transparency of the object to be separated, such as a laser displacement meter sensor, the color and transparency data of the resin piece 4 are taken in advance with a photoelectric sensor before the thickness measurement, and the displacement is measured. It is necessary to send data to the total 7 and correct the amount of reflection to the correct amount by an arbitrary method.

  In order to measure the thickness of the resin, the surface of the end of the conveyor 3 or the position of the surface of the conveyor 3 near the resin piece 4 is used as a reference plane, and the resin piece 4 is obtained from the displacement data as shown in FIG. Find the thickness of the. Moreover, when the thickness of the conveyor 3 is known, a displacement measuring meter may be provided on the back surface of the conveyor 3, and the resin thickness may be measured based on the back surface. In the present invention, the thickness of the resin piece 4 refers to the value of the thickest portion of the resin thickness obtained from the displacement data.

A correction method based on the thickness of the resin piece 4 will be described. When an X-ray having an intensity I ₀ is incident on a material having a thickness t and the intensity of the transmitted X-ray is I, the relationship between I ₀ and I is expressed by the following formula (1) according to Lambert-Beer's law.
I = I ₀ · exp (−μt) (1)
It is represented by In equation (1), μ is a linear absorption coefficient, and is proportional to the product of the density of the measurement object and the mass absorption coefficient.

FIG. 4 shows three types of resin pieces having a thickness of 1 mm, 2 mm, and 3 mm for resins having a bromine content of 0%, 1%, and 10%, respectively, and X-rays are applied to these resin pieces. is a graph showing transmittance when irradiated _{(I / I 0 × 100 (} %)). The horizontal axis indicates the thickness (mm) of the resin piece, and the vertical axis indicates the normalized transmission X-ray absorption intensity. Here, the normalized transmission X-ray absorption intensity refers to a value normalized by setting the transmission X-ray absorption intensity when there is no resin piece as 1. The normalized transmission X-ray absorption intensity tends to decrease as the thickness of the resin piece increases and the bromine concentration increases as described above (Equation (1)). Even in a resin piece having a bromine content of 0% by mass, the normalized transmission X-ray absorption intensity decreases as the thickness increases because X-rays are absorbed by carbon or the like in the resin piece. A broken line shown in FIG. 4 is a transmission X-ray absorption intensity threshold value for discriminating between a bromine-containing resin piece and a bromine-free resin piece when the thickness is not corrected. For example, as shown in FIG. 4, when the bromine content is 1% and the transmission X-ray absorption intensity of a resin piece having a thickness of 1 mm is set as a threshold for selection, if the threshold or less is determined as a bromine-containing resin, Since the resin pieces having a bromine content of 0% and a thickness of 2 mm and 3 mm are below the threshold value, they are erroneously judged as bromine-containing resin pieces even though they do not contain bromine.

  FIG. 5 shows the normalized transmission using the above-mentioned law (Equation (1)) and correcting the transmission X-ray absorption intensity of the resin pieces having a thickness of 2 mm and 3 mm as the resin piece having a thickness of 1 mm. It is a graph which shows X-ray absorption intensity. Specifically, the transmission X-ray absorption intensity per unit thickness was calculated based on the transmission X-ray absorption intensity of 2 mm and 3 mm in thickness, and corrected as a resin piece having a thickness of 1 mm. In addition, in the case of a resin having a non-uniform thickness, such a correction based on the thickness is set so that the value based on the displacement measurement data is corrected so that the thickest portion of the resin thickness becomes the resin thickness. This is achieved here. The dashed line in FIG. 5 is a transmission X-ray absorption intensity threshold value for discriminating between a bromine-containing resin piece and a bromine-free resin piece when the thicknesses of 2 mm and 3 mm resin pieces are corrected to 1 mm. Before the correction, the resin pieces having a bromine content of 0% and a thickness of 2 mm and 3 mm were identified as bromine-containing resin pieces (see FIG. 4). However, the correction had a bromine content of 0% and a thickness of 2 mm and 3 mm. Since the normalized transmission X-ray absorption intensity of the resin piece is equal to or higher than the threshold value, it is not mistaken for a bromine-containing resin piece.

  In this way, the thickness of the resin piece 4 is measured using the sorting apparatus of the present invention, and the transmission X-ray absorption intensity is corrected based on the thickness data, so that the bromine-containing resin and the bromine-free resin are mistaken. It is possible to sort with high accuracy without judgment. As a result, the mixture of brominated flame retardants in the bromine-free resin can be suppressed, and the recovery rate of the bromine-free resin used for the recycled material is dramatically improved. Moreover, since there is no misjudgment as mentioned above, it is not necessary to examine the disposal method separately at the time of disposal of the separation object. In addition, according to the sorting apparatus of the present invention, since it is possible to sort the bromine-containing resin and the bromine-free resin with high accuracy, there is no need to provide a further sorting step and the like, and the energy required for recovery is suppressed. Can do.

  The present invention also provides a first step of measuring the thickness of a separation object, a second step of detecting transmitted X-rays of the separation object, and a separation object by using the sorting apparatus having the above configuration. A third step of sorting the product, wherein the third step sorts the transmitted X-ray intensity detected in the second step based on the intensity corrected based on the thickness of the separation object measured in the first step. A method for selecting a flame retardant-containing resin can be provided.

  The first step can be performed using the displacement meter 7 as shown in FIG. Moreover, what is necessary is just to use the said X-ray detector 5 for a 2nd process. In the correction based on the thickness of the separation target, the transmitted X-ray absorption intensity per unit thickness is calculated for each separation target as described in FIG. 5 so that a resin piece having a specific thickness is obtained. Further, it can be performed by correcting the transmission X-ray absorption intensity. Note that the selection in the third step can be achieved by the separator 9 such as separation by wind pressure.

  2 and 3 (a), the side surface of the sorting device is shown. However, even when resin pieces are randomly stacked on the conveyor, the x- and y-axes are used in the X-ray detector. By taking into account the two-dimensional coordinates, it is possible to obtain the data of the thickness and transmission X-ray absorption intensity of the resin pieces 4 that are the objects to be selected. Is possible.

(Embodiment 2)
FIG. 6 is a graph showing a calibration curve measured with a resin containing bromine having a threshold concentration for discriminating between a bromine-containing resin and a bromine-free resin bromine. In the data processing unit, the thickness data of transmission X-rays and the intensity threshold value of transmission X-rays shown in FIG. 6 are provided as calibration curves, so that the transmission X-ray intensity data detected by the X-ray detector 5 and the displacement meter By performing sorting in the separation unit based on the data based on the intensity threshold value in the thickness of the resin piece 4 that is the separation target measured in step 7, high-precision sorting is possible. That is, the thickness of the resin piece 4 obtained by the displacement measuring meter 7 determines the normalized transmission X-ray absorption intensity threshold value for determining whether the resin piece 4 contains bromine or does not contain bromine from the calibration curve of FIG. If the transmitted X-ray absorption intensity detected by the X-ray detector 5 is less than or equal to the threshold value, it is determined as a bromine-containing resin piece, and is selected by the separation unit 9 to be stored in the brominated flame retardant-containing resin piece storage box 10. The On the other hand, when the transmitted X-ray absorption intensity exceeds the threshold value, it is determined as a bromine-free resin, and is selected by the separation unit 9 to be stored in the brominated flame retardant-free resin piece storage box 11.

  As described above, the data processing unit uses the sorting device having the thickness and transmission X-ray intensity threshold data measured in advance, thereby measuring the thickness of the separation target, and the separation target The method includes a second step of detecting transmitted X-rays and a third step of selecting a separation target. The third step includes data of thickness and transmission X-ray intensity threshold values measured in advance, and transmission X-ray intensity data. And the data which compared the intensity | strength threshold value in the thickness of the measured separation target object can be provided, and the method of classifying | selecting a bromine containing resin and a bromine non-containing resin can be provided.

  Thus, by using the calibration curve prepared in advance and the thickness of the resin piece 4 measured by the displacement meter, the bromine-containing resin and the bromine-free resin can be selected with high accuracy. As a result, the mixture of brominated flame retardants in the bromine-free resin can be suppressed, and the recovery rate of the bromine-free resin used for the recycled material is dramatically improved. Moreover, since there is no misjudgment as mentioned above, it is not necessary to examine the disposal method separately at the time of disposal of the separation object. In addition, according to the sorting apparatus of the present invention, since it is possible to sort the bromine-containing resin and the bromine-free resin with high accuracy, there is no need to provide a further sorting step and the like, and the energy required for recovery is suppressed. Can do.

  Although the embodiment of the present invention has been described as above, it is also planned from the beginning to appropriately combine the configurations of the above-described embodiments and examples.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  According to the sorting apparatus and the sorting method of the present invention, accurate sorting can be performed regardless of the thickness of the sorting target. Moreover, since it is possible to specify the concentration of various impurities as well as bromine, the sorting device of the present invention can be applied even if the sorting object is changed and the substance is changed.

It is a side view which shows the typical example of a structure of the X-ray detector which concerns on Embodiment 1 of this invention. It is a schematic diagram which shows the structure of the selection apparatus which concerns on Embodiment 1 of this invention. (A) It is a side view which shows the structure of the measurement part which concerns on Embodiment 1 of this invention, (b) It is a figure which shows the relationship between a selection resin piece and a displacement. It is a graph which shows the relationship between the normalization X-ray intensity which concerns on this invention, and the thickness of a resin piece. It is a graph which shows the relationship between the normalization X-ray intensity correct | amended with the thickness which concerns on Embodiment 1 of this invention, and the original thickness of a resin piece. It is a graph which shows the calibration curve for distinguishing the bromine containing resin piece which concerns on Embodiment 2 of this invention, and a bromine non-containing resin piece.

Explanation of symbols

  1 X-ray source, 2 X-ray irradiation area, 3 conveyor, 4 resin piece, 4a bromine-containing resin piece, 4b bromine-free resin piece, 5 X-ray detector, 6 sorting resin piece feeder, 7 displacement meter, 8 Data processing unit, 9 separation unit, 10 bromine-containing resin piece storage box, 11 bromine-free resin piece storage box, 12 laser.

Claims (2)

A bromine-based flame retardant-containing resin sorting device including an X-ray source that generates X-rays, an X-ray detector that detects transmitted X-rays transmitted through a resin piece , a data processing unit, and a separation unit,
The sorting device further includes a displacement meter,
The displacement meter measures the thickness of the resin piece, sends a thickness data of the measured resin piece to the data processing unit,
The X-ray detector detects transmitted X-rays that have passed through the resin piece , sends the detected transmitted X-ray intensity data to the data processing unit,
The data processing unit includes data of transmitted X-ray intensity threshold values for the resin pieces having a predetermined thickness measured in advance to select a brominated flame retardant-containing resin.
Correction data obtained by correcting the intensity data of transmitted X-rays sent from the X-ray detector into the intensity data of the predetermined thickness based on the thickness data of the resin pieces sent from the displacement meter, Comparing with the intensity threshold, and sending the comparison data regarding whether the correction data is below the intensity threshold or exceeds the intensity threshold to the separation unit,
The separation unit is a sorting device for a brominated flame retardant-containing resin, which sorts a resin piece whose correction data is equal to or lower than the strength threshold based on the comparison data as a brominated flame retardant-containing resin. A first step of measuring the thickness of the resin piece ;
A second step of detecting transmitted X-rays of the resin piece ;
A third step of selecting the resin pieces ,
In the third step , the transmission X-ray intensity data of the resin piece detected in the second step is calculated based on the resin piece thickness data measured in the first step. Comparing the correction data corrected to the intensity data with the data of the transmission X-ray intensity threshold value for the resin piece having a predetermined thickness measured in advance to select the brominated flame retardant-containing resin,
A method for selecting a brominated flame retardant-containing resin , wherein a resin piece whose correction data is equal to or less than the strength threshold is selected as a brominated flame retardant-containing resin based on the comparison result .

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