JP6771159B2 - Resin determination method and equipment - Google Patents

Description

The present invention relates to a resin determination method and an apparatus for a resin color in a sorting target in which a plurality of types of small pieces are collected.

Due to mass consumption and mass disposal type economic activities, global environmental problems such as global warming or resource depletion are occurring.

Under these circumstances, the Home Appliance Recycling Law has been enforced in Japan since April 2001 with the aim of building a resource-recycling society. The Home Appliance Recycling Law requires the recycling of used home appliances (for example, air conditioners, TVs, refrigerators, freezers, washing machines, clothes dryers, etc.). As a result, used home appliances are crushed into small pieces at a home appliance recycling factory, then sorted and collected for each grade using magnetism, wind power, vibration, etc., and recycled as recycled materials. ing. As resin materials, polypropylene (hereinafter referred to as PP), polystyrene (hereinafter referred to as PS), or acrylonitrile-butadiene-styrene (hereinafter referred to as ABS) are widely used in home appliances, and resins are used. Each resin type is sorted and recovered by a sorting device utilizing the absorption characteristics of the near infrared region (for example, wavelength range 1 to 3 μm) due to the molecular structure of the above.

This resin sorting device can irradiate a resin piece conveyed on a conveyor with light including a near-infrared region, detect a reflection or absorption spectrum from the resin in a non-contact manner, and determine a resin type. Therefore, in such an apparatus, a large amount of resin pieces can be sorted.

However, in black resins and the like containing carbon black (that is, carbon-based fine particles) used in small household appliances or automobiles, light in the near infrared region is absorbed, so that a reflection or absorption spectrum can be obtained. However, it is a big problem that it cannot be sorted.

Patent Document 1 proposes an apparatus that takes into consideration the above-mentioned problems related to the recycling of resin materials. In the technique described in Patent Document 1, in the black waste plastic material identification device 101 as shown in FIG. 5, the black waste plastic piece 102 flowing on the transport conveyor 103 is irradiated with the infrared light source 104. Next, the reflected light 110 is detected by the mid-infrared sensor 105. Next, the reflection spectrum peculiar to the resin type in the mid-infrared region (for example, the wavelength region of 3 to 5 μm) in which the influence of carbon black is reduced as shown in FIG. 6 is acquired, and the resin type can be determined.

Japanese Patent No. 5376145

Generally, the resin piece to be sorted is in a state where the resin type and the resin color are mixed, and it is necessary to sort each resin type and resin color.

However, with the technique described in Patent Document 1 shown in FIG. 5, it is not possible to accurately determine whether the resin is white or black, and in order to select the resin color, a visible light color sorting device is used. Must be used in combination. As a result, since sorting is performed using two devices, a mid-infrared sorting device and a visible light color sorting device, the processing time becomes long. Even in the apparatus shown in FIG. 5, a method of determining between a white resin and a black resin based on the amount of light received by the mid-infrared sensor 105 by utilizing the fact that the black resin containing carbon black has less reflected light than the white resin. Can be considered.
However, the resin pieces after crushing the waste home appliances to be sorted have a problem that the surface state of the resin pieces varies greatly and the resin color cannot be determined with high accuracy. The intensity of the reflected light changes greatly depending on the inclination angle or unevenness of the resin surface, the variation in roughness such as whether the surface is a glossy surface or a diffused surface, and the like. The longer the wavelength of light, the less the influence of carbon black. Therefore, the difference in intensity of reflected light depending on the presence or absence of carbon black is smaller in the mid-infrared light region than in visible light or near-infrared light. Therefore, in the mid-infrared region, the influence of the variation in the surface state on the amount of reflected light becomes relatively large, and it becomes difficult to determine the resin color with high accuracy.

The present invention solves the above-mentioned conventional problems, and is a resin determination method for determining the color of a resin with high accuracy by suppressing the influence of the surface state of the resin as much as possible by using the reflection or absorption spectrum in the mid-infrared region. The purpose is to provide the device.

The present invention is configured as follows in order to achieve the above object.

According to the resin determination method according to one aspect of the present invention.
Irradiate the object to be sorted with infrared light,
The reflected light from the sorting object irradiated with the infrared light is received, and the light is received.
Of the reflection or absorption spectrum obtained by the reflected light, in order to reduce the spectral change caused by carbon dioxide in the wavelength region affected by carbon dioxide and the wavelength region before and after it, the amount of infrared light of the infrared detection unit is increased. The signal output correlation is adjusted so that it differs between the wavelength region affected by carbon dioxide and the wavelength regions before and after it, and contains a region of 4.22 to 4.29 μm in which the influence of carbon dioxide occurs. The spectral intensity of the wavelength band with the lower limit value of .48 to 4.22 μm and the upper limit value of 4.29 to 4.48 μm was acquired as the spectral intensity for resin color determination.
Correlation information between the acquired spectral intensity for determining the resin color and the spectral data of one or more types of resin colors acquired in advance was obtained.
From the obtained correlation information, the resin color associated with the highest correlation information equal to or higher than the preset threshold value is determined as the resin color of the object to be sorted.

According to the resin determination device according to another aspect of the present invention.
An irradiation unit that irradiates the object to be sorted with infrared light,
A light receiving unit that receives reflected light from the sorting object that has been irradiated with the infrared light from the irradiation unit, and a light receiving unit that receives the reflected light.
An arithmetic processing unit that determines the resin color of the sorting object from the reflection or absorption spectrum of the resin that is the sorting target based on the reflected light.
With
The arithmetic processing unit
In the reflection or absorption spectrum, in order to reduce the spectral change caused by carbon dioxide in the wavelength region affected by carbon dioxide and the wavelength region before and after it, the correlation of the signal output with the amount of infrared light of the infrared detection unit is determined. , 3.48 to 4.22 μm, which contains a region of 4.22 to 4.29 μm in which the influence of carbon dioxide occurs, adjusted so as to be different between the wavelength region affected by carbon dioxide and the wavelength region before and after the influence of carbon dioxide. Is a lower limit value, and a spectral intensity acquisition unit that acquires the spectral intensity of the wavelength band having an upper limit value of 4.29 to 4.48 μm as the spectral intensity for resin color determination , and
An evaluation unit for obtaining correlation information between the spectrum intensity for determining the resin color acquired by the spectrum intensity acquisition unit and spectrum data of one or more types of resin colors acquired in advance, and an evaluation unit.
Among the correlation information obtained by the evaluation unit, it has a determination unit that determines a resin color associated with the highest correlation information that is equal to or higher than a preset threshold value as the resin color of the sorting object.

According to the resin determination method and apparatus according to the above aspect of the present invention, the lower limit value is 3.48 to 4.22 μm and 4.29 to 4.48 μm is set by using the reflection or absorption spectrum in the mid-infrared region. Correlation information of the spectral intensity of the wavelength band used as the upper limit is used. With this configuration, the influence of the surface condition of the resin can be suppressed as much as possible, and the color of the resin can be determined with high accuracy.

Schematic diagram of the resin determination device according to the first embodiment of the present invention. Graph of resin spectrum obtained in Embodiment 1 of the present invention Graph of resin spectrum used for determination in Embodiment 1 of the present invention A flowchart showing a flow in which the resin determination device determines a resin according to the first embodiment of the present invention. Schematic diagram of the apparatus in the conventional resin determination described in Patent Document 1. Graph of black reflection spectrum derived from automobile in the conventional resin determination described in Patent Document 1.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 is a schematic view of the resin determination device 1 according to the first embodiment.

The resin 2 is an example of an object to be sorted, and is a resin in which resin colors are mixed. The configuration of the resin determination device 1 for determining the resin color from the resin 2 with high accuracy will be described with reference to FIG.

The resin determination device 1 includes at least an infrared detection unit 8 having an irradiation unit 8a and a light receiving unit 8b, and an arithmetic processing unit 10.

The irradiation unit 8a irradiates the resin 2, which is an example of the object to be sorted, with irradiation light 3 such as infrared rays (that is, infrared light).

The light receiving unit 8b receives the reflected light 4 such as infrared rays (that is, infrared light) from the resin 2 irradiated with the irradiation light 3 from the irradiation unit 8a.

The arithmetic processing unit 10 determines the resin color of the object to be sorted from the reflection or absorption spectrum of the resin 2 based on the reflected light 4.

Specifically, the arithmetic processing unit 10 has at least a spectrum intensity acquisition unit 10b, a spectrum evaluation unit 10c, and a resin determination unit 10d.

The spectrum intensity acquisition unit 10b acquires the spectrum intensity based on the reflected light 4. First, the analog data of the reflected light 4 received by the light receiving unit 8b is input from the light receiving unit 8b to the spectrum intensity acquisition unit 10b of the arithmetic processing unit 10 through the digital data conversion device 9. In the digital data conversion device 9, the analog data of the reflected light 4 is converted into the digital data of the reflected light 4. The spectrum intensity acquisition unit 10b calculates the reflection or absorption spectrum of the resin 2 based on the input digital data of the reflected light 4, and then uses the calculated reflection or absorption spectrum as, for example, the reflection or absorption spectrum and the spectrum intensity. After converting to a table format or a graph format showing the relationship between the above, the spectral intensity for resin determination is obtained from the table or graph.

At this time, the spectral intensity acquisition unit 10b sets the spectral intensity of the wavelength region of the reflection or absorption spectrum, with 3.48 to 4.22 μm as the lower limit and 4.29 to 4.48 μm as the upper limit, for resin determination. Obtained as the spectral intensity of. The purpose of acquiring the spectral intensity in such a wavelength region is to acquire the spectral intensity in the band affected by carbon dioxide so that the obtained reflection or absorption spectrum can be easily determined.

The spectrum evaluation unit 10c obtains a plurality of correlation information between the spectrum intensity for resin determination acquired by the spectrum intensity acquisition unit 10b and the spectrum data of one or more kinds of resin colors acquired in advance.

The resin determination unit 10d selects the resin color associated with the highest correlation information, which is equal to or higher than the preset threshold value, among the plurality of correlation information obtained by the spectrum evaluation unit 10c, as the resin color of the resin 2 to be selected. Is determined to be.

The infrared detection unit 8 has a function of irradiating the resin 2 with infrared irradiation light 3 and a function of receiving the reflected light 4 from the resin 2 of the irradiation light 3. The infrared detection unit 8 is connected to the arithmetic processing unit 10 via the digital data conversion device 9.

An electric signal output according to the reflected light 4 is input to the digital data conversion device 9 from the infrared detection unit 8. The digital data conversion device 9 converts the input electric signal into digital data, and then outputs the converted digital data to the arithmetic processing unit 10.

The arithmetic processing unit 10 calculates the reflection or absorption spectrum of the resin 2 based on the digital data output from the digital data conversion device 9, and then acquires the spectral intensity for resin determination from the calculated reflection or absorption spectrum. Acquired in part 10b.

In FIG. 1, the belt of the belt conveyor 5 is moving at a constant speed, and the belt conveyor 5 is an example of a transfer unit that transfers the resin 2. The belt conveyor 5 transfers the resin 2 from the charging area 6 to the detection area 7 along the longitudinal direction of the belt conveyor 5.

Further, the infrared detection unit 8 is arranged above the detection area 7 of the belt conveyor 5 so as to face each other. In the detection region 7, the resin 2 is irradiated with the irradiation light 3 from the irradiation unit 8a, and the reflected light 4 reflected by the resin 2 is received by the light receiving unit 8b.
The arithmetic processing unit 10 analyzes the information output from the digital data conversion device 9, and acquires the reflection or absorption spectrum of the resin 2 in the spectrum intensity acquisition unit 10b. Further, the arithmetic processing unit 10 uses the spectrum intensity acquisition unit 10b to acquire the spectral intensity of the band affected by carbon dioxide as the spectral intensity for resin determination so that the obtained reflection or absorption spectrum can be easily determined. To process. Further, the arithmetic processing unit 10 collates the spectrum data of the resin color registered in advance with the acquired spectrum intensity for resin determination by the spectrum evaluation unit 10c, and the resin color of the resin 2 is matched by the resin determination unit 10d. judge.

Here, a method in which the arithmetic processing unit 10 calculates the spectral intensity for resin determination from the digital data input to the arithmetic processing unit 10 will be briefly described.

The electric signal photoelectrically converted by the light receiving unit 8b of the infrared detection unit 8 according to the reflected light 4 depends on the intensity of the received light. Therefore, it is possible to acquire information on the intensity of the reflected light 4 from the resin 2 from the digital data converted by the digital data conversion device 9. From the acquired intensity of the reflected light 4, the spectral intensity acquisition unit 10b can acquire the spectral intensity for resin determination of the resin 2.
From the spectral intensity for resin determination, the spectral intensity acquisition unit 10b processes the spectral intensity for resin determination for determining the resin color using the carbon dioxide absorption band, and determines the resin color of the resin 2.

Here, before explaining the method for determining the resin color according to the first embodiment, the influence of carbon dioxide and the resin color generated in the mid-infrared region (for example, wavelength region 3 to 5 μm) will be described with reference to FIG. To do.

FIG. 2 shows the resin spectra of four samples of a black ABS resin derived from a home appliance containing carbon black, a black PS resin, a black PP resin, and a white ABS resin derived from a home appliance not containing carbon black. The graph of is shown. That is, FIG. 2 is a graph obtained by acquiring the spectral intensities in the wavelength band of 4.10 μm to 4.80 μm for each of these four samples. In the graph of FIG. 2, the wavelength band is taken on the horizontal axis and the reflection intensity is taken on the vertical axis.

Carbon dioxide existing in the atmosphere is an unsaturated molecule having a linear structure, and four types of vibrations exist as molecular vibrations, such as two types of variable angle vibrations, symmetric stretching vibrations, and inverse symmetric stretching vibrations. To do. Of these, two types of eccentric oscillations are motions in which the valence angle changes periodically around the carbon atom, and light absorption occurs around 15.0 μm. Further, the symmetric stretching vibration is a vibration symmetrical with respect to the direction of the valence, and does not appear in the infrared spectrum because it does not have a fixed bipolar efficiency like carbon dioxide.
However, in the inverse symmetric expansion and contraction vibration, which is a vibration asymmetric in the direction of the valence, light absorption occurs centering around 2349 cm ^{-1 when} expressed in terms of a wavelength of 4.25 μm and a wave number which is the reciprocal of the wavelength. In addition, since carbon dioxide is gaseous in the atmosphere, it is more excited than the molecular vibrations of solids or liquids, and the absorption spectrum appears more prominently.

In the mid-infrared region (for example, wavelength region 3 to 5 μm), infrared absorption occurs due to the inverse symmetric stretching vibration, and when the reflection or absorption spectrum from the object is obtained in a non-contact manner, the object and the detection element Since air exists as a medium between the two, the spectrum to be detected will be affected by carbon dioxide. In FIG. 2, in the black PP resin, the black PS resin, and the black ABS resin, the spectral change can be confirmed in the wavelength region 70 of 4.18 μm or more and 4.42 μm or less with a peak of around 4.25 μm. In addition, in the black ABS resin and the white ABS resin, the nitrile contained in the ABS resin

C≡N

Due to the expansion and contraction vibration of, the wavelength is 4.48 μm, and the spectral change can be confirmed with the peak around 2230 cm ^-1 in the wave number expression.

On the other hand, in FIG. 2, in the white ABS resin, the spectra observed in the black PP resin, the black PS resin, and the black ABS resin in the wavelength region 70 of 4.18 μm or more and 4.42 μm or less with a peak of about 4.25 μm. I can't see the change. The reason for this is that in the wavelength region affected by carbon dioxide, the effect of light absorption peaking at around 4.25 μm due to the inverse symmetric expansion and contraction vibration of carbon dioxide and the effect of carbon black that correlates with the resin color of resin 2 It is affected by both the influence and the influence, but in the wavelength region before and after that, there is no influence of light absorption, and only the influence of carbon black is caused.

In FIG. 2, in the white resin, the signal output with respect to the amount of infrared light of the infrared detection unit 8 is reduced so that the spectral change due to carbon dioxide is reduced in the wavelength region affected by carbon dioxide and the wavelength regions before and after it. The correlation has been adjusted. Therefore, the correlation of the signal output with respect to the amount of infrared light input to the infrared detection unit 8 is different between the wavelength region affected by carbon dioxide and the wavelength regions before and after it. As a result, in FIG. 2, due to the influence of carbon black, the black PP resin, the black PS resin, and the black ABS resin have a spectrum in the wavelength region 70 of 4.18 μm or more and 4.42 μm or less with a peak of around 4.25 μm. You can see the change.

Depending on the method of adjusting the correlation of the signal output with the amount of infrared light input to the infrared detection unit 8, the effect of light absorption due to the inverse symmetric expansion and contraction vibration of carbon dioxide and the effect of carbon black, which correlates with the resin color of the resin 2, The change situation of the spectrum due to and is different. In the wavelength region affected by carbon dioxide and the wavelength region before and after it, the wavelength region affected by carbon dioxide is used by using a calibration jig that is close to the reflection intensity of white resin and can obtain uniform intensity at each wavelength. Adjustments are made in the atmosphere so that spectral changes are as small as possible in the wavelength region before and after. With this configuration, a spectrum close to that of FIG. 2 can be obtained.

Next, in order to determine the resin color of the resin 2 in the spectrum intensity acquisition unit 10b, the wavelength region is set to 3.48 to 4.22 μm as the lower limit value and 4.29 to 4.48 μm as the upper limit value. The reason for setting is described below.

First, the theoretical wavelength at which carbon dioxide vibrates in inverse symmetry is 4.25 μm, and the wave number representation is 2349 cm ^-1 . It is preferable that the wavelength band affected by carbon dioxide always contains a region of 2349 ± 20 cm ^-1 in wave number expression and 4.22 to 4.29 μm in wavelength expression.

Further, since PP, PS, and ABS are often used in the resin material, in order to determine the resin color of the resin 2, the influence of the resin species specific spectrum on PP, PS, and ABS is suppressed as much as possible. Need to keep. In FIG. 2, it is confirmed that the spectral change peaks at a wavelength of 4.48 μm and a wave number expression of around 2230 cm ^{-1 due} to the expansion and contraction vibration of the nitrile contained in the ABS resin. Therefore, the spectral change due to the expansion and contraction vibration of the nitrile from 4.29 μm, which is the upper limit value that is preferable to always include the upper limit value of the wavelength region for determining the resin color of the resin 2 as the wavelength band affected by carbon dioxide. By setting the peak wavelength up to 4.48 μm, it is possible to suppress the influence of the spectrum due to the ABS resin.

Next, regarding the spectra of PP resin and PS resin, the wavelength peaks at 3.48 μm due to the expansion and contraction vibration of the methyl group in the PP resin and around 2870 cm- ^{1 in the} wave number expression, and the wavelength 3 due to the expansion and contraction vibration of the benzene ring in the PS resin. Spectral changes occur at peaks of .27 μm and around 3055 cm ^{-1 in} wavenumber representation. Therefore, as the lower limit of the wavelength region for determining the resin color of the resin 2, carbon dioxide has an effect from 3.48 μm, which is the longer wavelength among the wavelengths at which the spectral changes of the PP resin and the PS resin occur. By setting the wavelength band up to 4.22 μm, which is a preferable lower limit value, it is possible to suppress the influence of the spectrum due to the PP resin and the PS resin.

In the wavelength region where 3.48 to 4.22 μm is the lower limit and 4.29 to 4.48 μm is the upper limit, the spectral shape change due to the influence of carbon dioxide is 4.18 μm or more and 4. 42 μm or less is a preferable wavelength region for determining the resin color of the resin 2. By utilizing the change in the spectral shape due to the influence of carbon dioxide, it is possible to determine the resin color of the resin 2 in a state where the influence of the intensity variation of the reflected light due to the surface variation of the resin 2 is suppressed as much as possible.
Further, in the wavelength region of 4.18 μm or more and 4.42 μm or less, the difference between the theoretical absorption wavelength of 4.48 μm of the nitrile group contained in the ABS resin and the upper limit of the wavelength region of 4.42 μm is 0.06 μm, which is small, and the nitrile. There remains the possibility of being affected by the group. The theoretical absorption wavelength of the methyl group contained in the PP resin is 3.48 μm and the lower limit of the wavelength region is 4.18 μm, which is 0.7 μm, which is unlikely to be significantly affected. The theoretical absorption wavelength of the benzene ring contained in the PS resin is 3.27 μm, and the possibility of being affected is even lower. In order to eliminate the influence of this nitrile group, in the wavelength region where the spectral shape change due to the influence of carbon dioxide is large 4.18 μm or more and 4.42 μm or less, the upper limit of the wavelength region is 4.42 μm, and the wave number is 2262 cm ^-1 . The upper limit of the wavelength region affected by carbon dioxide is 4.29 μm, and in the wave number expression, 4.34 μm, which is shorter than the middle of 2329 cm- ¹ , is set as the upper limit of the wavelength region. In other words, the wavelength region is 4. It is preferable to narrow the wavelength to 18 μm or more and 4.34 μm or less.
The reason for setting the upper limit of the wavelength region to 4.34 μm will be described below. The wavelength resolution required for discriminating the change in the spectral shape of carbon dioxide is insufficient at 0.01 μm in the wavelength representation, and is preferably 0.0075 μm in the wavelength representation and 4 cm ^-1 in the wave number representation. Considering 4 cm ^-1 as one block, the origin is 2329 cm ^-1 , which is the upper limit wavelength of the wavelength region affected by carbon dioxide, and 2265 cm ^{-1 in the} 16th block is within the wavelength region where the spectral shape change is large due to the influence of carbon dioxide. It becomes the upper limit of. For the purpose of eliminating the influence of nitrile groups, the upper limit of the wavelength region that is compatible with the ease of extracting the characteristics of the spectral shape change of carbon dioxide is closer to the upper limit of the wavelength region affected by carbon dioxide than the one block less than the midpoint. As a value, it is preferable to narrow the region. The 8th block of the midpoint is 2297 cm ^-1 in wavenumber representation and 4.353 μm in wavelength representation, and one block less than the midpoint is 2301 cm ^-1 in wavenumber representation and 4.346 μm in wavelength representation. When expressing the number of effective digits with a wavelength of two digits after the decimal point, the wavelength of 4.34 μm and the wave number expression of 2304 cm ^-1 are closer to the upper limit of the wavelength range affected by carbon dioxide than the one block less than the midpoint. It is the upper limit to be set.

FIG. 3 is a graph of a resin spectrum having a wavelength region of 4.18 μm or more and 4.42 μm or less used for determination in the first embodiment of the present invention. Using the four types of spectral intensities shown in FIG. 3, the correlation coefficient using the spectral intensities as an example of the correlation information was obtained, and it was verified whether the determination was possible. Correlation coefficient

は、下記の（１）式によって求められる。

Is obtained by the following equation (1).

．．．(１)

.. .. .. (1)

：基準スペクトルの平均強度、

：比較スペクトルの平均強度、である。 here,
x: Reference spectral intensity,
y: Comparative spectral intensity,

: Average intensity of reference spectrum,

: The average intensity of the comparison spectrum.

When the reflection spectrum of the black ABS resin is used as the reference spectrum using the above equation (1), the correlation coefficient of each resin is 0.96 for the black PS resin and 0.79 for the black PP resin. The white ABS resin was 0.22. As for the correlation coefficient, the higher the degree of agreement with the reference spectrum, the closer the absolute value of the correlation coefficient approaches 1, so that the black PS resin or black PP resin is higher than the white ABS resin with respect to the black ABS resin. It shows the degree of agreement. Therefore, the correlation coefficient is the color of black and white by using the spectral intensity of the wavelength band of 4.18 μm or more and 4.42 μm or less, which is affected by light absorption by carbon dioxide, regardless of the resin type. It shows that the judgment is possible.

Next, a method of detecting the resin color of the resin 2 using the resin determination device 1 will be described.

The light source of the irradiation unit 8a that irradiates the irradiation light 3 in the infrared detection unit 8 is a light source having a broad wavelength region such as a blackbody light source or a single wavelength light source having an absorption wavelength region of the resin to be determined. Use a light source with one or more. Further, the light receiving element of the light receiving unit 8b in the infrared detection unit 8 is provided with a light receiving element that receives the reflected light 4 for each wavelength from the light source. The digital data conversion device 9 converts the analog data from the light receiving element into digital data and sends it to the arithmetic processing unit 10. The arithmetic processing unit 10 calculates the reflection intensity of each wavelength, that is, the spectral intensity, based on the digital data output from the light receiving element sent from the digital data conversion device 9, and the spectral intensity in the band where the influence of carbon dioxide occurs. Is evaluated to determine the resin color of the resin 2.

Specifically, a spectrum intensity as a sample is obtained from a resin whose physical properties are known in advance, and a spectrum for resin determination in a band affected by carbon dioxide is obtained from the spectrum intensity obtained from the resin 2 to be determined. Find the strength. Next, the correlation coefficient between the obtained spectral intensity and the sample spectral intensity is calculated by the equation (1), and the resin color of the resin 2 is determined by a determination algorithm that compares the result with a preset threshold value.
Here, as the determination algorithm, the method using the correlation coefficient has been described, but other methods such as using regression analysis are appropriately selected.

Next, the operation of the resin determination device 1 of FIG. 1 will be described with reference to the flowchart of FIG.

Here, the flow until the resin color is determined by focusing on one resin 2a among the plurality of existing resins 2 will be described in detail. Here, the resin 2a is an ABS resin.

First, in step S1, the resin 2 is charged into the charging area 6 on the belt conveyor 5 moving at a constant speed, and is conveyed to the detection area 7 by the belt conveyor 5.

Next, in step S2, the infrared detection unit 8 irradiates the resin 2a that has reached the detection region 7 with the irradiation light 3 from the light source.

Next, in step S3, the infrared detection unit 8 detects the reflected light 4 from the resin 2a that has reached the detection region 7. The reflected light 4 is the light reflected from the resin 2a by the irradiation light 3.

Next, in step S4, the analog data of the reflected light 4 detected by the infrared detection unit 8 is converted into digital data from the infrared detection unit 8 through the digital data conversion device 9, and then output to the arithmetic processing unit 10. The arithmetic processing unit 10 acquires the reflection or absorption spectrum of the resin 2 by the spectrum intensity acquisition unit 10b based on the input digital data of the reflected light 4. From the reflection or absorption spectrum acquired by the spectrum intensity acquisition unit 10b, the spectral intensity for resin determination in the band affected by the above-mentioned carbon dioxide (for example, the wavelength band of 4.18 μm or more and 4.42 μm or less) is acquired. Acquired in part 10b.

Next, in step S5, each sample spectrum is obtained from a sample spectrum of a resin having known physical properties acquired in advance by the spectrum evaluation unit 10c and a resin determination spectral intensity acquired by the spectrum intensity acquisition unit 10b. The correlation coefficient of is calculated by the spectrum evaluation unit 10c and evaluated.

Next, in step S6, based on the correlation coefficient with each sample spectrum and the preset threshold value, it is assumed that the resin having the highest correlation coefficient equal to or higher than the threshold value is the resin color of the resin 2 of the selection target. The determination unit 10d determines.

As described above, according to the resin determination method according to the first embodiment, when the resin 2 of the selection target is determined and selected using the reflection or absorption spectrum in the mid-infrared region, the light absorption by carbon dioxide is absorbed. Correlation information of the spectral intensity of the wavelength band having an affected lower limit of 3.48 to 4.22 μm and an upper limit of 4.29 to 4.48 μm can be used. With this configuration, the influence of the surface condition of the resin and the spectrum of the resin type is suppressed as much as possible, and the resin in which the resin color of the resin 2 and the resin type are mixed is selected as an example of the object to be sorted. The resin color of a certain resin 2 can be determined with high accuracy.

The present invention is not limited to the first embodiment, and can be implemented in various other embodiments. For example, as a modification of the first embodiment, as shown in FIG. 2, when the resin 2 of the object to be sorted is determined and sorted by using the reflection or absorption spectrum in the infrared region, the influence of light absorption by carbon dioxide. In the spectrum other than the wavelength band where the lower limit value is 3.48 to 4.22 μm and the upper limit value is 4.29 to 4.48 μm, the resin type can be determined in addition to the resin color determination. is there. In the example of FIG. 2, it is possible to determine the ABS resin. By combining the first embodiment and this modification, it is possible to determine the resin color and the resin type of the resin 2. On the other hand, in the technique described in Patent Document 1, since the resin color of the resin 2 cannot be sorted with high accuracy, it is necessary to use a color sorting device for visible light in combination. By combining the above and the modified example, it is possible to simultaneously determine the resin color and the resin type of the resin 2 by the sorting device in the mid-infrared region.
In addition, by appropriately combining any embodiment or modification of the various embodiments or modifications, the effects of each can be achieved. Further, it is possible to combine embodiments or examples, or to combine embodiments and examples, and it is also possible to combine features in different embodiments or examples.

The resin determination method and apparatus according to the above aspect of the present invention have a lower limit of 3.48 to 4.22 μm and an upper limit of 4.29 to 4.48 μm, which are affected by light absorption by carbon dioxide. By using the correlation information of the spectral intensity of the wavelength band, the selection target is selected from the resin in which the resin color and the resin type are mixed while the influence of the surface state of the resin and the spectrum by the resin type is suppressed as much as possible. The resin color of the above can be determined with high accuracy. Since the resin determination method and apparatus can quickly determine black resin or the like containing carbon black (that is, carbon-based fine particles) using mid-infrared rays, a plurality of sorting objects can be quickly selected. It can be used in recycling processes and the like.

1 Resin judgment device 2 Resin 2a Resin 3 Irradiation light 4 Reflected light 5 Belt conveyor 6 Input area 7 Detection area 8 Infrared detection unit 8a Irradiation unit 8b Light receiving unit 9 Digital data conversion device 10 Calculation processing unit 10b Spectrum intensity acquisition unit 10c Spectrum evaluation Part 10d Resin determination part 70 Wavelength region of 4.18 μm or more and 4.42 μm or less

Claims (8)

Irradiate the object to be sorted with infrared light,
The reflected light from the sorting object irradiated with the infrared light is received, and the light is received.
Of the reflection or absorption spectrum obtained by the reflected light, in order to reduce the spectral change caused by carbon dioxide in the wavelength region affected by carbon dioxide and the wavelength region before and after it, the amount of infrared light of the infrared detection unit is increased. The signal output correlation is adjusted so that it differs between the wavelength region affected by carbon dioxide and the wavelength regions before and after it, and contains a region of 4.22 to 4.29 μm in which the influence of carbon dioxide occurs. The spectral intensity in the wavelength region with the lower limit value of .48 to 4.22 μm and the upper limit value of 4.29 to 4.48 μm was acquired as the spectral intensity for resin color determination.
Correlation information between the acquired spectral intensity for determining the resin color and the spectral data of one or more types of resin colors acquired in advance was obtained.
A resin determination method for determining whether or not the resin color of the sorting object is black or not, based on the correlation information that is equal to or higher than a preset threshold value and is the highest among the obtained correlation information. The resin determination method according to claim 1, wherein the wavelength region is 4.18 μm or more and 4.42 μm or less. The resin determination method according to claim 2, wherein the wavelength region is 4.34 μm or less. The resin determination method according to claim 1, 2 or 3, wherein the correlation information is a correlation coefficient using spectral intensity. An irradiation unit that irradiates the object to be sorted with infrared light,
A light receiving unit that receives reflected light from the sorting object that has been irradiated with the infrared light from the irradiation unit, and a light receiving unit that receives the reflected light.
An arithmetic processing unit that determines whether or not the resin color of the sorting object is black from the reflection or absorption spectrum of the resin that is the sorting target based on the reflected light.
With
The arithmetic processing unit
In the reflection or absorption spectrum, in order to reduce the spectral change caused by carbon dioxide in the wavelength region affected by carbon dioxide and the wavelength region before and after it, the correlation of the signal output with the amount of infrared light of the infrared detection unit is determined. , 3.48 to 4.22 μm, which contains a region of 4.22 to 4.29 μm in which the influence of carbon dioxide occurs, adjusted so as to be different between the wavelength region affected by carbon dioxide and the wavelength region before and after the influence of carbon dioxide. And a spectral intensity acquisition unit that acquires the spectral intensity in the wavelength region with 4.29 to 4.48 μm as the upper limit value as the spectral intensity for resin color determination .
An evaluation unit for obtaining correlation information between the spectrum intensity for determining the resin color acquired by the spectrum intensity acquisition unit and spectrum data of one or more types of resin colors acquired in advance, and an evaluation unit.
Among the correlation information obtained by the evaluation unit, it has a determination unit for determining whether or not the resin color of the sorting object is black or not based on the highest correlation information that is equal to or higher than a preset threshold value. Resin judgment device. The resin determination device according to claim 5, wherein the wavelength region in the arithmetic processing unit is 4.18 μm or more and 4.42 μm or less. The resin determination device according to claim 6, wherein the wavelength region in the arithmetic processing unit is 4.34 μm or less. The resin determination device according to claim 5, 6 or 7, wherein the correlation information is a correlation coefficient using spectral intensity.

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